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Dr Jay Guo

Biography

Prof. Yingjie Jay Guo is the founding Director of Global Big Data Technologies Centre and Distinguished Professor at University of Technology, Sydney. Jay is an internationally established scientist with over 300 publications and expertise in antennas and wireless communications systems, an innovator with strong and sustained industrial impact and a globally recognised R&D leader with proven track record. Jay is a Fellow of the Australian Academy of Engineering(ATSE), a Fellow of IEEE, and a Fellow of the Institute of Engineering and Technology (IET). He is the recipient of Australia Government Engineering Innovation Award (2012), Australia Engineering Excellence Award (2007) and CSIRO Chairman's Medal (2007 & 2012). He was named to one of the top 100 most influential engineers in Australia in 2014 and 2005. He joined the College of Experts of the Australian Research Council in 2015.

Jay has over twenty years of international academic, industrial and CSIRO experience. He has successfully directed R&D programs across a number of fields in ICT including 3G network technology development, wireless and networking, broadband applications, robotics, sensor networks and big data technologies. Prior to joining CSIRO in August 2005, Jay held a number of senior positions in the European mobile communications industry.

Image of Jay Guo
Distinguished Professor, School of Electrical and Data Engineering
Director, Global Big Data Technologies
Core Member, Global Big Data Technologies
Antennas and Propagation
Fellow, Institute of Electrical and Electronics Engineers
Fellow, Institution of Engineering and Technology
Fellow, Australian Academy of Technological Sciences and Engineering (FTSE)
 
Phone
+61 2 9514 2982

Research Interests

Antennas adn applied electromagnetics

Wireless communications and 5G

Wireless sensing and IoT

Big data technologies

Can supervise: Yes

Books

Yu, K., Sharp, I. & Guo, Y.J. 2009, Ground-Based Wireless Positioning.
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Ground Based Wireless Positioning provides an in-depth treatment of non-GPS based wireless positioning techniques, with a balance between theory and engineering practice. The book presents the architecture, design and testing of a variety of wireless positioning systems based on the time-of-arrival, signal strength, and angle-of-arrival measurements. These techniques are essential for developing accurate wireless positioning systems which can operate reliably in both indoor and outdoor environments where the Global Positioning System (GPS) proves to be inadequate. The book covers a wide range of issues including radio propagation, parameter identification, statistical signal processing, optimization, and localization in large and multi-hop networks. A comprehensive study on the state-of-the-art techniques and methodologies in wireless positioning and tracking is provided, including anchor-based and anchor-free localisation in wireless sensor networks (WSN). The authors address real world issues such as multipath, non-line-of-sight (NLOS) propagation, accuracy limitations and measurement errors. Presenting the latest advances in the field, Ground Based Wireless Positioning is one of the first books to cover non-GPS based technologies for wireless positioning. It serves as an indispensable reference for researchers and engineers specialising in the fields of localization and tracking, and wireless sensor networks. * Provides a comprehensive treatment of methodologies and algorithms for positioning and tracking * Includes practical issues and case studies in designing real wireless positioning systems * Explains non-line-of-sight (NLOS) radio propagation and NLOS mitigation techniques * Balances solid theory with engineering practice of non-GPS wireless systems. © 2009 John Wiley & Sons, Ltd.

Chapters

Guo, Y.J. & Qin, P.Y. 2016, 'Reconfigurable Antenna Arrays for Wireless Communications' in Handbook of Antenna Technologies, Springer.
The Handbook of Antenna Technologies aims to present the rapid development of antenna technologies, particularly in the past two decades, and also showcasing the newly developed technologies and the latest applications.
zhang, J., Huang, X., Dyadyuk, V. & guo, Y. 2016, 'Hybrid Antenna Array for mmWave Massive MIMO' in mmWave Massive MIMO: A paradigm for 5G, Elsevier.
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Dyadyuk, V., Huang, X., Stokes, L., Pathikulangara, J., Weily, A., Nikolic, N., Bunton, J. & Guo, Y. 2011, 'Adaptive Antenna Arrays for Ad-Hoc Millimetre-Wave Wireless Communications' in Advanced Trends in Wireless Communications.
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Conferences

Guan, D., Ding, C. & Guo, Y.J. 2017, 'A compact multi-beam antenna without beam forming network', ISAP 2016 - International Symposium on Antennas and Propagation, pp. 404-405.
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© 2016 IEICE. A novel approach to design a multi-beam array antenna without a beam forming network (BFN) is presented. The proposed antenna consists of 33 microstrip patches that are tightly coupled through microstrip lines. By exciting any one of these patches, the energy can be coupled to all the patches. Nine beams towards different directions are obtained by selecting different feeding ports. The resultant gain varies from 10 dBi to 11 dBi. The scanning ranges of the beams are ±24° and ±45° in the elevation and horizontal directions, respectively. The proposed antenna has a single-layered structure without complex feeding network, which significantly lowers its cost.
Zhu, H.L., Ding, C., Wei, G. & Guo, Y.J. 2017, 'A novel base station antenna based on rectangular waveguide', ISAP 2016 - International Symposium on Antennas and Propagation, pp. 196-197.
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© 2016 IEICE. A novel base station antenna element is proposed. It consists of a surface of parallel strips to rotate the polarization direction and a segment of a rectangular waveguide. The surface is designed on a single-sided substrate, which has the same area as the aperture of the waveguide. In assembling, the non-copper side of the substrate is placed in direct contact with the aperture of the waveguide antenna. To achieve the polarization rotation, the parallel strips on the surface are rotated by 45° with respect to the walls of the waveguide antenna. By adding the surface, the linear polarization direction of the rectangular waveguide antenna is rotated by 45° to comply with the requirements of cellular industry. SMA connector with a conical probe is used as the coaxial-to-waveguide adaptor. Results have shown that the proposed antenna has a fractional impedance bandwidth of 35%, and a stable radiation pattern is also achieved.
Kong, F., Sun, X., Leung, V.C.M., Guo, Y.J., Zhu, Q. & Zhu, H. 2017, 'Queue-aware small cell activation for energy efficiency in two-tier heterogeneous networks', IEEE Wireless Communications and Networking Conference, WCNC.
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© 2017 IEEE. In heterogeneous networks (HetNets), the network energy efficiency is critically determined by the base station (BS) deployment density. In this paper, we consider a BS density optimization problem by turning on only a fraction of micro BSs according to an activation ratio to minimize the network average power consumption per area in a 2- tier HetNet. In contrast to previous studies where a BS is assumed to be transmitting packets all the time, such that the network power consumption monotonically increases as the BS density increases, we assume that each BS can be busy or idle depending on the dynamic packet arrivals. The network power consumption is thus closely related to the average traffic intensity of each tier. With the assumption of universal spectrum reuse, the average traffic intensity of each tier is found to be uniquely determined by a set of fixed-point equations, based on which the network average power consumption per area is characterized. Simulation results demonstrate that the network average power consumption per area can be minimized by properly tuning the activation ratio. It is further revealed that the optimal activation ratio increases as the mean packet arrival rate of each user increases.
Qin, P., Guo, J. & Bah, A.O. 2016, 'An Extremely Wideband Tapered Balun for Application inTightly Coupled Arrays', ICEAA-IEEE APWC, Cairns.
Ji, L.Y., Qin, P.Y., Guo, Y.J., Fu, G. & Mittra, R. 2016, 'A wideband polarization reconfigurable antenna for WLAN applications', 2016 10th European Conference on Antennas and Propagation, EuCAP 2016, European Conference on Antennas and Propagation, IEEE, Davos, Switzerland.
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© 2016 European Association of Antennas and Propagation.This paper proposes a wideband polarization reconfigurable antenna design for WLAN applications. It consists of a shorted annular patch (SAP) antenna as the source, a partially reflective surface (PRS) structure to enhance the gain, and a reconfigurable Wilkinson power divider as the feed network. The antenna can electronically alter its polarization between linear polarization (LP), left-hand circular polarization (LHCP), and right-hand circular polarization (RHCP),achieving an overlapped 10dB impedance bandwidth and 3 dB axial-ratio bandwidth of 4.68-5.33 GHz (13%), thus outperforming most of the reported polarization reconfigurable antennas in terms of the frequency bandwidth.
Zhu, H.L., Cheung, S.W., Guo, Y.J., Ding, C. & Yuk, T.I. 2016, 'Aperture efficiency improvement using metasurface', 2016 10th European Conference on Antennas and Propagation, EuCAP 2016, European Conference on Antennas and Propagation (EuCAP), IEEE, Davos, Switzerland.
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© 2016 European Association of Antennas and Propagation.A method to improve the aperture efficiency of antennas using a non-uniform metasurface (MS) is studied in this paper. For illustration, a patch antenna and a planar MS having unit cells of square patches with different sizes are used. The sizes of the square patches on the MS follow a radial gradient index function. The aperture efficiencies of the patch antenna and the antenna using the MS are compared. For easy comparison, the patch antenna is designed to have an aperture size of 00, where the 0 is wavelength at the operating frequency in free space. Simulation results show that, by placing the MS atop the patch antenna with a separating distance of 35 mm, the directivity of the patch antenna can be increased from 9.7 dBi to 11.6 dBi. With the aperture size remains unchanged, the aperture efficiency of the patch antenna is increased by more than 100%.
Qin, P.Y., Guo, Y.J., Ji, L.Y. & Wei, F. 2016, 'A single-layer wideband reflectarray with sub-wavelength phase-shifting elements', 2016 IEEE Antennas and Propagation Society International Symposium, APSURSI 2016 - Proceedings, IEEE Antennas and Propagation Society International Symposium, APSURSI, IEEE, Puerto Rico, pp. 1415-1416.
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© 2016 IEEE.A single-layer wideband reflectarray antenna employing sub-wavelength phase-shifting elements is presented. The element is composed of double concentric square meander line rings and its size is a fifth of a wavelength. By changing the length of the meander line, a phase variation range of about 360° is achieved with an almost constant slop across the 9 to 11 GHz. Using this element, a 48 48 - element reflectarray antenna is designed. A measured 1.5-dB gain bandwidth of 18 % is achieved.
Li, H., Huang, X. & Guo, Y. 2016, 'Improved Quality-Based Channel State Feedback Scheme in Multicast Systems with Greedy Scheduling', the 2016 International Symposium on Communications and Information Technologies (ISCIT2016), Qingdao, China.
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Zhang, J., Hay, S. & Guo, Y. 2016, 'Directional Antennas for Point-to-Multipoint Millimetre Wave Communications', 2016 IEEE-APS Topical Conference on Antennas and Propagation in Wireless Communications (APWC), Cairns, QLD, 2016.
Gao, X., Du, J., Weily, A.R., Zhang, T., Foley, C.P. & Guo, Y.J. 2016, 'Broadband Antenna-Coupled High-Temperature Superconducting Josephson-Junction Mixer for Terahertz Communication Applications', Infrared, Millimeter, and Terahertz waves (IRMMW-THz), 2016 41st International Conference on, International Conference on Infrared, Millimeter, and Terahertz waves, IEEE, Copenhagen.
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This paper presents a broadband terahertz (THz) high-temperature superconducting (HTS) mixer based on a log-periodic antenna-coupled YBa2Cu3O7-x (YBCO) step-edge Josephson junction. The THz thin-film antenna, as well as the microwave coupling circuits, have been carefully designed to optimize the power transmission from and into the junction while realizing good isolation between the DC bias, local-oscillator (LO) and intermediate-frequency (IF) ports. This mixer device has been fabricated, packaged and characterized to demonstrate a frequency down-conversion capability with a view to potential application in THz wireless communication systems.
Karmokar, D.K., Guo, Y.J., Qin, P.Y., Esselle, K.P. & Bird, T.S. 2016, 'A dual-band half-width microstrip leaky-wave antenna for beam scanning in the forward and backward directions', Proceedings of the 2016 18th International Conference on Electromagnetics in Advanced Applications, ICEAA 2016, International Conference on Electromagnetics in Advanced Applications (ICEAA), Cairns, QLD, Australia, pp. 816-819.
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© 2016 IEEE.A microstrip leaky-wave antenna (LWA) loaded periodically with C-shaped slots is described. Uniform half-width (HW) microstrip LWAs (HW-MLWAs) operate in a single band and radiate a main beam that scans only in the forward direction. The proposed antenna operates in two frequency bands and the main beam can be steered in both the forward and backward directions by sweeping the frequency. The -10 dB reflection bandwidths of the antenna are 4.2 to 4.9 GHz and 8.23 to 8.8 GHz. The beam scanning ranges of the antenna are 22° to 59° and -76° to -18° when the frequency is swept from 4.2 to 5 GHz and 7.85 to 8.9 GHz, respectively.
Chen, X., Guo, Y.J., Qin, P.Y. & Fu, G. 2016, 'Low-cost 3D printed compact circularly polarized antenna with high efficiency and wide beamwidth', Proceedings of the 2016 18th International Conference on Electromagnetics in Advanced Applications, ICEAA 2016, International Conference on Electromagnetics in Advanced Applications (ICEAA), IEEE, Cairns, Queensland, Australia, pp. 497-500.
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© 2016 IEEE.A novel compact circularly polarized (CP) microstrip antenna is presented. The antenna introduces a circular radiation patch with a crossed slot to improve the impedance matching and reduce the antenna sizes. Meanwhile, triangular feed patches are adopted to increase the bandwidth. A no-resistor series feed line is used for achieving a high antenna efficiency. Based on the above method, the antenna is constructed by three low-cost PCBs which form a solid and light structure. The profile and the diameter of the antenna are just 0.0640 and 0.280 respectively (0 is the wavelength in free space). The impedance bandwidth for VSWR2 is 20.8%, and the AR bandwidth for AR3dB is 8.3%. In the overlap band, the radiation efficiency can reaches more than 95%, and the gains are over 5.2dBic. Especially, the beamwidth for AR3dB can cover more than 128°.
Yang, X., Zhao, G., Hu, W., Guo, Y.J., Yin, Y.Z. & Bah, A.O. 2016, 'Characteristics of wideband phased array with two-layer metasurface', Proceedings of the 2016 18th International Conference on Electromagnetics in Advanced Applications, ICEAA 2016, 2016 International Conference on Electromagnetics in Advanced Applications (ICEAA), IEEE, Cairns, Australia, pp. 852-855.
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&copy; 2016 IEEE.The agile beam scanning ability is attractive feature of phased array over traditional mechanical array, but it is difficult to achieve perfect impedance matching in all the directions. Furthermore, phased array capable of wideband operation is desired in multi-function radar and modern communication systems. In this paper, a wideband tightly coupled array models equipped with two-layer metasurface is presented and its characteristics are investigated. The metasurface consists of two substrates each printed with different periodic metallic patches to accommodate wideband and wide angle applications. The results show that, with the assistance of this artificial metasurface, the phased array can operate over a 5:1 ratio impedance bandwidth (VSWR<3) and the scanning angle is as large as 45&deg;.
Ye, L., Cao, K., Guo, J., Huang, X., Beadle, P., Argha, A., Piccardi, M., Zhang, G. & Su, S.W. 2016, 'Inertial sensor based post fall analysis for false alarming reduction', Telehealth and Assistive Technology / 847: Intelligent Systems and Robotics, IASTED International Conference on Telehealth and Assistive Technology, TAT 2016, Acta Press, Zurich, Switzerland, pp. 36-43.
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One of the major public health problems among elderly people is falling injury. This study investigates fall detection and prevention by using inertial sensors for which the major existing challenging is how to significantly reduce false alarming in order to enhance the acceptance of elderly users during rehabilitation and daily exercises. Different from most existing approaches in the literature, the behavior after falling will be analyzed in details, which can not only greatly reduce false alarming, but also significantly improves the accuracy of the assessment of the severity of falling injuries.
Zhang, J., Huang, X. & Guo, Y. 2015, 'Adaptive Searching and Tracking Algorithm for AoA Estimation in Localized Hybrid Array', IEEE ICC2015 - Workshop on 5G & Beyond - Enabling Technologies and Applications, London, UK.
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Ding, C., Sun, H., Guo, Y., Qin, P. & Yang, Y. 2015, 'Beamwidth Control of Base Station Antennas Employing Reflectors and Directors', International Symposium on Antennas and Propagation, IEEE, Hobart, Tasmania, Australia, pp. 1-3.
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Ji, L.Y., Guo, Y.J., Qin, P.Y. & Fu, G. 2015, 'A reconfigurable beam-scanning partially reflective surface (PRS) antenna', 2015 9th European Conference on Antennas and Propagation, EuCAP 2015, 2015 9th European Conference on Antennas and Propagation (EuCAP), IEEE, Lisbon, Portugal, pp. 1-3.
&copy; 2015 EurAAP. A novel reconfigurable partially reflective surface (PRS) antenna is presented in this paper. The beam scanning ability is realized by employing a reconfigurable PRS structure and a phased array as the source. The design achieves a beam switching between -15&deg;, 0&deg;, to 15&deg; with respect to the broadside direction from 5.5 GHz to 5.7 GHz with the realized gains over 12 dBi. Good agreement between the simulated and measured results is achieved.
Guo, Y.J. & Qin, P.Y. 2015, 'Advances in reconfigurable antennas for wireless communications', 2015 9th European Conference on Antennas and Propagation, EuCAP 2015, 2015 9th European Conference on Antennas and Propagation (EuCAP), IEEE, Lisbon, Portugal, pp. 1-4.
&copy; 2015 EurAAP. This paper presents an overview of the recent advances in frequency, polarization and pattern reconfigurable antennas for wireless communications. In particular, it reports our latest progress in this research field, including a wideband to narrowband frequency tunable antenna, a dual-band polarization reconfigurable antenna, a beam-steering quasi-Yagi dipole antenna and a beam-steering antenna array based on reconfigurable defected microstrip structure (RDMS).
Ding, C., Guo, Y.J., Qin, P.Y., Dutkiewicz, E. & Yang, Y. 2015, 'A phased array antenna employing reconfigurable defected microstrip structure (RDMS)', IEEE Antennas and Propagation Society, AP-S International Symposium (Digest), pp. 2469-2470.
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&copy; 2015 IEEE. In this paper, a compact phase-shifting unit based on reconfigurable defected microstrip structure (RDMS) is used to provide controllable phase shift for a 14 phased array antenna. The RDMS is made by etching two slots on the microstrip line and loading with PIN diodes. By controlling the working states of the employed PIN diodes, the RDMS is able to provide phase shift. A 14 phased array antenna is built employing optimized RDMS. The tested results show that the antenna can work in the frequency band from 5.1-5.4 GHz, and switch its beam to -15&deg;, 0&deg;, and 15&deg; in the H-plane with the average gain of 10 dBi. Compared to our previous work, significantly size reduction of 55% is achieved with similar performance.
Huang, X., Zhang, A. & Guo, Y.J. 2015, 'Joint Transmitter and Receiver I/Q Imbalance Estimation in Presence of Carrier Frequency Offset', 2015 15th International Symposium on Communications and Information Technologies (ISCIT), International Symposium on Communications and Information Technologies (ISCIT2015), IEEE, Nara, Japan, pp. 209-212.
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This paper proposes a simple frequency domain joint transmitter and receiver I/Q imbalance estimation method which exploits the phase rotation introduced by carrier frequency offset. Using two frequency domain training sequences inserted in each transmission frame, the transmitter and receiver I/Q imbalances can be jointly estimated over multiple frames. The transmitter I/Q imbalance parameter can be fed back to the transmitter for I/Q imbalance pre-compensation, whereas the receiver I/Q imbalance can be compensated locally followed by conventional frequency domain equalization. Numerical simulation results show that the image rejection ratios for both transmitter and receiver after I/Q imbalance compensation can be improved to over 50 dB which is necessary for multichannel systems with high order modulation and wide transmission bandwidth.
Ji, L.-.Y., Fu, G., Gong, S.-.X., Zhang, T., Guo, Y.J., Qin, P.-.Y., Ding, C. & IEEE 2015, 'Pattern Reconfigurable Fabry-Perot Cavity Antenna', Proceedings of the 2015 International Symposium on Antennas and Propagation (ISAP), International Symposium on Antennas and Propagation (ISAP).
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A newly designed pattern reconfigurable Fabry-Perot cavity antenna is presented in this paper. The reconfigurability is achieved by employing a phased array with a reconfigurable feed network as the source of the FPC antenna. The design can switch its main beam direction between 10&deg; and 10&deg; with respect to the broadside direction from 5.36 GHz to 5.76 GHz. The realized gain of the proposed antenna is over 11.6 dBi. Good agreement between the simulated and measured results is achieved.
Huang, X., Zhang, J.A. & Guo, Y.J. 2014, 'Comprehensive imperfection mitigation for precoded OFDM systems', Communications (ICC), 2014 IEEE International Conference on, IEEE, pp. 5932-5937.
Huang, X., Guo, Y.J. & Zhang, J.A. 2014, 'Multi-gigabit microwave and millimeter-wave communications research at CSIRO', 14th International Symposium on Communications and Information Technologies, ISCIT 2014, 2014 14th International Symposium on Communications and Information Technologies (ISCIT), Institute of Electrical and Electronics Engineers Inc., Incheon, pp. 542-546.
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High speed and long range wireless backhauls are cost-effective alternatives to fibre networks and becoming more and more attractive as the demand for broadband wireless services grows rapidly in recent years. However, current commercially available wireless backhaul systems neither provide sufficiently high speed nor meet the requirements to achieve both high speed and long range at the same time with sufficiently low latency for targeted applications. Traditional microwave systems can achieve long transmission range, but the data rates are limited to a few hundred Mega bits per second only. Multi-Gigabit wireless communications can be achieved using millimetre-wave (mm-wave) frequency bands, especially the E-bands, but the practical transmission range is still a major weakness. In this paper, the state-of-the-art microwave and mm-wave technologies developed at the Commonwealth Scientific and Industrial Research Organization (CSIRO) are introduced to demonstrate CSIRO's technology leadership in multi-Gigabit wireless communications research and development. The technology trends in multi-Gigabit wireless communications are also discussed and various recently developed microwave and mm-wave systems are compared. It is hoped that this paper will stimulate further research interest and industry development.
Huang, X., Zhang, J.A. & Guo, Y.J. 2014, 'Unified out-of-band emission reduction with linear complexity for OFDM', 2014 IEEE/CIC International Conference on Communications in China, ICCC 2014, IEEE/CIC ICCC 2014 Symposium on Wireless Communications Systems, Institute of Electrical and Electronics Engineers Inc., Shanghai, China, pp. 523-527.
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This paper proposes a unified out-of-band emission (OOBE) reduction framework with linear complexity for orthogonal frequency-division multiplexing (OFDM) systems. Unlike conventional spectral precoding approaches which use orthogonal precoding matrixes, this framework composes cancellation signals from the linear combinations of data symbols and minimizes the average OOBE power with a general least-squares solution. A joint frequency domain cancellation subcarrier and data domain cancellation symbol allocation scheme is also proposed for discrete Fourier transform precoded OFDM, by which the overall signal processing complexity of the OFDM transceiver is further reduced without impact on other system performance. The advantages of the proposed scheme is verified both analytically and by simulation as compared with some well-known low-complexity OOBE reduction schemes.
Ding, C., Guo, Y.J., Qin, P.-.Y., Ji, L. & Yang, Y. 2014, 'A compact phase shift unit for analogue beamforming', Antenna Technology:" Small Antennas, Novel EM Structures and Materials, and Applications"(iWAT), 2014 International Workshop on, IEEE, pp. 93-95.
Du, J., Zhang, T. & Guo, Y.J. 2014, 'Novel high-Tc superconducting devices for wireless communications and imaging', 2014 International Workshop on Antenna Technology: Small Antennas, Novel EM Structures and Materials, and Applications, iWAT 2014, pp. 122-125.
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&copy; 2014 IEEE. High-T c superconducting (HTS) materials have ultralow surface resistance values at microwave frequencies, which have been applied to make high-Q resonators and 'super filters' with narrow-bandwidth, low insertion losses, and superior out-of-band rejections. The second important property of HTS materials is related to low-noise Josephson junctions made from the HTS thin films. In recent years, novel nonlinear high-frequency devices, most of them exploiting the unique features of the AC Josephson effect, have been developed. Applications of the HTS devices based on Josephson junctions have been extended from lower electromagnetic bands (microwave) into mm-wave and terahertz, regions. An overview of CSIRO's recent research activities and achievements in developing novel HTS devices for applications to wireless communication and imaging is presented in this paper.
Wei, F., Shi, X.W., Qin, P.Y. & Guo, Y.J. 2014, 'Compact UWB power divider with unequal distribution ratio', Antenna Technology:" Small Antennas, Novel EM Structures and Materials, and Applications"(iWAT), 2014 International Workshop on, IEEE, pp. 297-299.
Guo, Y.J., Qin, P.-.Y. & Ding, C. 2014, 'Low-cost beamforming employing reconfigurable antennas', Antenna Technology:" Small Antennas, Novel EM Structures and Materials, and Applications"(iWAT), 2014 International Workshop on, IEEE, pp. 155-158.
Qin, P.-.Y., Guo, Y.J. & Ding, C. 2014, 'A polarization reconfigurable antenna for dual-band operation', Antenna Technology:" Small Antennas, Novel EM Structures and Materials, and Applications"(iWAT), 2014 International Workshop on, IEEE, pp. 65-67.
Qin, P.-.Y., Guo, Y.J. & Weily, A.R. 2014, 'A sub-wavelength reflectarray element based on double square rings loaded with meander lines', Antennas and Propagation (EuCAP), 2014 8th European Conference on, IEEE, pp. 2296-2298.
Ding, C., Guo, Y.J., Qin, P.-.Y. & Yang, Y. 2014, 'A reconfigurable defected microstrip structure for applications in phase shifter', Antennas and Propagation (EuCAP), 2014 8th European Conference on, IEEE, pp. 2342-2346.
Qin, P.-.Y., Guo, Y.J. & Wei, F. 2014, 'Frequency agile monopole antenna using a reconfigurable bandpass filter', Antennas and Propagation Society International Symposium (APSURSI), 2014 IEEE, IEEE, pp. 1250-1251.
Ding, C., Guo, Y.J., Qin, P.-.Y. & Yang, Y. 2014, 'A compact phase-shifting unit for phased array antennas', European Radar Conference (EuRAD), 2014 11th, IEEE, pp. 443-446.
Ding, C., Guo, Y.J., Qin, P.Y. & Yang, Y. 2014, 'A compact phase-shifting unit for phased array antennas', European Microwave Week 2014: Connecting the Future, EuMW 2014 - Conference Proceedings; EuMC 2014: 44th European Microwave Conference, pp. 1746-1749.
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&copy; 2014 European Microwave Association. A compact reconfigurable defected microstrip structure (RDMS) unit is proposed for phase shifters used in phased array antennas. The RDMS unit can introduce a phase shift when working in two different states. The performance of the RDMS unit, including the phase shift and insertion loss, is found to have closely correlations with some key dimensions, which is elucidated using equations and simulations. A RDMS unit with optimized dimensions is fabricated as an example, and measured to have a phase shift of 20&deg; at 5.2 GHz. Then, two of such RDMS units are cascaded, resulting in a 1-bit phase shifter which has a doubled phase shift but smaller insertion loss. The proposed phase shifter is compact, low cost, and easy to be fabricated and integrated in microstrip systems. Therefore, it offers a low-cost and low-profile solution to phase shifts in phased array antennas.
Gómez-Tornero, J.L., Alvarez-Melon, A., Mesa, F., Medina, F., Goussetis, G. & Jay Guo, Y. 2014, 'Analysis and design of controllable leaky-wave antennas inspired by Prof. Arthur Oliner a tribute to Prof. Oliner', European Microwave Week 2014: Connecting the Future, EuMW 2014 - Conference Proceedings; EuMC 2014: 44th European Microwave Conference, pp. 440-443.
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&copy; 2014 European Microwave Association. In this paper, we make a summary on the different leaky-wave antenna (LWA) technologies developed by Spanish groups in collaboration with UK and Australia, and which have been inspired by seminal works of Prof. Oliner. First, we will describe the LWAs based on asymmetric waveguides proposed by Prof. Oliner and collaborators in the 80s-90s. Also, the labor of Prof. Oliner to reveal the nature of leaky modes in microstrip lines will be reminded. Based on these pioneering works, the contribution of the authors to the analysis and design of LWAs in three distinct technologies will be described. Namely: hybrid waveguide-printed circuit technology, Fabry-P&eacute;rot (FP) technology, and Substrate Integrated Waveguide (SIW) technology. The control of the complex leaky-mode wavenumber is necessary for the synthesis of high-gain frequency scanning patterns. This paper gives an overview of the working mechanism and taper principles used for each technology, in a tribute to Prof. Oliner and collaborators who inspired all these ideas.
Cantoni, A., Zhang, J., Huang, X. & Guo, Y.J. 2013, 'Impact of sampling rate on PSD of OFDM signal with SSOP sidelobe suppression', Signal Processing Advances in Wireless Communications (SPAWC), 2013 IEEE 14th Workshop on, IEEE, pp. 629-633.
Huang, X., Joseph, J., Zhang, J.A. & Guo, Y.J. 2013, 'Sample rate conversion with parallel processing for high speed multiband OFDM systems', WCNC, IEEE.
Ding, C., Guo, Y.J., Qin, P.-.Y., Bird, T.S. & Yang, Y. 2013, 'A Novel phase shifter based on reconfigurable defected microstrip structure (RDMS) for beam-steering antennas', Antennas & Propagation (ISAP), 2013 Proceedings of the International Symposium on, IEEE, pp. 993-996.
Qin, P.-.Y., Guo, Y.J. & Ding, C. 2013, 'A microstrip dual-band polarization reconfigurable antenna', Antennas and Propagation Society International Symposium (APSURSI), 2013 IEEE, IEEE, pp. 1640-1641.
Cheng, P., Chen, Z., Qiu, C., Gui, L., Guo, Y.J. & Rui, Y. 2013, 'Stream maximization transmission for MIMO systems with limited feedback unitary precoding', IEEE Vehicular Technology Conference.
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Limited feedback precoding (LFP) significantly improves multiple-input multiple-output (MIMO) spatial multiplexing link reliability with a small amount of feedback from the receiver back to the transmitter. One of the key problems linked to LFP is how to select an optimal precoder from a predetermined unitary codebook. We find that the conventional precoder selection criteria are not applicable to the stream maximization transmission (SMT) mode with linear receivers, including zero forcing (ZF) and minimum mean square error (MMSE) decoders. To solve this issue, a novel singular value decomposition (SVD) based precoder selection criterion is proposed in this paper. This criterion features a unified structure for all the linear receivers such as ZF and MMSE decoders, and is shown by simulation to provide significant coding gains in various SMT systems. With the same complexity as the conventional one, the proposed criterion could find its applications in next generation systems employing SMT spatial multiplexing, significantly improving system performance with affordable feedback requirement. &copy; 2013 IEEE.
Chan, K.Y., Ramer, R. & Guo, Y.J. 2013, 'Switchable waveguide iris filter using planar dipoles', IEEE MTT-S International Microwave Symposium Digest.
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A new concept of switching on and off high Q-factor bandpass filters is presented. Cheap, planar, low Q-factor circuits are proposed to disable 3D filters Reconfigurable dipoles are used to disable resonance and turn the filter off, rather than adjusting the resonance frequency or coupling. Here wire bonded dipoles on quartz substrates inside the waveguide structure are used for switching the bandpass filters. 3-pole bandpass filters are proposed for concept demonstration The dipoles are inserted in each cavity of the iris waveguide filter. Central frequency is 24GHz and bandwidth 500MHz. Simulation results show good performance. The fabricated filter shows good correlation between the measured and simulated performance. The bandpass response is completely off, when the dipoles are "switched on"/connected with bondwires, confirming the introduced concept. The insertion loss is expected to be significantly reduced by choosing a superior fabrication method of the waveguide. &copy; 2013 IEEE.
Cheng, P., Chen, Z., Guo, Y.J. & Gui, L. 2013, 'Distributed bayesian compressive sensing based blind carrier-frequency offset estimation for interleaved OFDMA uplink', IEEE International Symposium on Personal, Indoor and Mobile Radio Communications, PIMRC, pp. 801-806.
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Carrier-frequency offset (CFO) estimation for orthogonal frequency-division multiplexing access (OFDMA) systems operating in multiuser uplink transmission is very challenging due to the presence of a multiple-parameter estimation problem. In this paper, we propose a novel blind CFO estimation method for interleaved OFDMA uplink based on distributed Bayesian compressive sensing (DBCS) theory. Considering the received signal structure, the new method first constructs a measurement matrix associated with a sparse signal matrix weight, which sets up the stage for the application of CS theory in tackling the original estimation problem. Then, the DBCS theory that exploits a common sparse profile of the sparse signal matrix weight is employed to distributively estimate a sparse hyperparameter vector, whose significant peaks are linked to the correct estimation of the multiple CFOs. Compared with the existing subspace theory based methods, the proposed scheme offers a significant enhancement in estimation accuracy, in specific in the low signal-to-noise ratio (SNR) region. The numerical results validate the effectiveness of the proposed scheme. &copy; 2013 IEEE.
Cheng, P., Chen, Z., Gui, L., Guo, Y.J., Tao, M. & Rui, Y. 2013, 'Distributed sparse channel estimation for OFDM systems with high mobility', IEEE International Conference on Communications, pp. 4951-4956.
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Channel estimation for an orthogonal frequency-division multiplexing (OFDM) broadband system operating with high mobility is very challenging. This is mainly due to the significant Doppler spread, inherent in a time-frequency doubly-selective (DS) channel. Consequently, a large number of channel coefficients must be estimated, forcing the need for allocating a large number of pilot subcarriers. To address this problem, we propose a novel channel estimation method based on basis expansion models (BEMs) and distributed compressive sensing (DCS) theory. To be specific, we develop a two-stage sparse BEM coefficients estimation method, which can effectively combat the Doppler spread and enable accurate channel estimation with dramatically reduced number of pilot subcarriers. The numerical results reveal that, in a typical LTE system configuration, the proposed scheme can increase the spectral efficiency by 40% and achieve a 6 dB gain in terms of normalized mean square error (NMSE), both compared to the conventional scheme. &copy; 2013 IEEE.
Chan, K.Y.E., Ramer, R. & Guo, Y.J. 2013, 'RF MEMS millimeter-wave switchable bandpass filter', 2013 IEEE International Wireless Symposium, IWS 2013.
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A switchable bandpass filter that can operate between 60 GHz and E-band spectrum, capable of providing good channel isolation is presented. A RF MEMS SPDT is designed for the switching element between the two bands. Back-to-back cantilever switches are used for maximum isolation. New circuit models for the inductively coupled inverters and short circuit stubs are proposed. Measurement results show good correlation to our simulations. Better than 15 dB return loss and 5 dB insertion loss in both 60 GHz and Eband are measured. With the introduction of transmission zero, rejection between the two operational bands is better than 20 dB. &copy; 2013 IEEE.
Li, X., Cui, Q., Tao, X., Yang, X., Rehman, W.U. & Guo, Y.J. 2013, 'Performance bounds of compressed sensing recovery algorithms for sparse noisy signals', IEEE Wireless Communications and Networking Conference, WCNC, pp. 2884-2889.
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Recently, the performance bounds of the compressed sensing (CS) recovery algorithms have been investigated in the noisy setting. However, most of the papers only focus on the noisy measurement model where the signal is noiseless and the noise enters after the CS operation. The noisy signal model where both the signal and the compressed measurements are contaminated by the different noises is not considered. This paper works on the noisy signal model and provides the performance bounds for the following popular recovery algorithms: thresholding and orthogonal matching pursuit (OMP), Dantzig selector (DS) and basis pursuit denoising (BPDN). The performance of the recovery algorithms is quantified as the 2 distance between the reconstructed signal and the true noisy signal. Next, the impacts of the noise are analyzed on the basis of the quantified performance. The analysis results show that the effective way to restrain the impact of the noise is to choose the measurement matrix with low correlation between the columns or the rows. Finally, the theoretical bounds are verified with numerical simulations by calculating the mean-squared-error for the different noise variances. The simulation results show that OMP owns the better performance than the other three recovery algorithms under the noisy signal model. &copy; 2013 IEEE.
Guo, Y.J., Qin, P.-.Y. & Bird, T.S. 2013, 'Reconfigurable antennas for wireless communications'.
Guzman-Quiros, R., Gomez-Tornero, J.L., Garcia-Vigueras, M., Weily, A.R. & Guo, Y.J. 2013, 'Advances in electronically reconfigurable LWAs in Fabry-Pérot and SIW technologies', 2013 7th European Conference on Antennas and Propagation, EuCAP 2013, pp. 2001-2005.
This paper gives an overview of our most recent research results on reconfigurable leaky-wave antennas (LWAs), which have been developed at Universidad Polit&eacute;cnica de Cartagena (Spain) and CSIRO ICT Centre (Australia). Fabry-P&eacute;rot and Substrate Integrated Waveguide (SIW) technologies are studied to propose new reconfigurable leaky-wave topologies for beamforming applications. &copy; 2013 EurAAP.
Guo, Y.J. & Gómez-Tornero, J.L. 2013, 'Reconfigurable Fabry-Pérot leaky-wave antennas', 2013 International Workshop on Antenna Technology, iWAT 2013, pp. 390-393.
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Beam scanning is an inherent property of Leaky-Wave Antennas (LWAs). It is usually achieved by sweeping the operating frequency. For wireless communications, however, it is necessary for the antenna to operate at a fixed frequency while scanning. With one dimensional LWAs, this can be done by electronically reconfiguring the leaky-line boundary condition. By altering the leaky-mode complex propagation constant, one can produce a desired scanning beam. To this end, a number of ideas have been investigated and reported in recent years, including the use of PIN diodes and photosensitive switches. The most used active device for electronically controlling 1D LWAs in microwave frequencies is the varactor diode, which has been applied to a multitude of leaky lines such as the slotline, the coplanar waveguide, the microstrip log-periodic line, the half-mode microstrip line , and the half-mode substrate-integrated waveguide. &copy; 2013 IEEE.
Wang, H., Cui, Q., Tao, X., Valkama, M. & Guo, Y.J. 2013, 'Optimal cooperative water-filling power allocation for OFDM system', IEEE Wireless Communications and Networking Conference, WCNC, pp. 3742-3747.
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It is well known that traditional water-filling provides a closed form solution for capacity maximization in orthogonal frequency division multiplex (OFDM) system. In this paper, cooperative power allocation is investigated in a two-transmitter multi-receiver model for OFDM systems. The local full channel state information (CSI) is available at the two transmitters respectively, where each transmitter has an individual power constrain. The transmitters first cooperate by sharing CSI, and then jointly optimize power allocation in the metric of sum throughput, which can be modeled as a convex optimization problem. Through an application of Karush-Kuhn-Tucker (KKT) conditions, the convex optimization problem is reformulated as a simplified convex one. Then the closed form solution is derived, which takes a form similar to classic water-filling principle. Based on the solution, the optimal cooperative power allocation algorithm is constructed, the structure of which can be explained as a cooperative water-filling relative to the traditional water-filling. Finally, numerical simulation is given to evaluate and demonstrate the performance of the optimal cooperative water-filling scheme. &copy; 2013 IEEE.
Gomez-Tornero, J.L., Goussetis, G. & Guo, J. 2013, 'Metasurfing substrate integrated waveguides to mold the radiation from Leaky Waves', Progress in Electromagnetics Research Symposium, pp. 206-211.
We show our latest developments in the application of the meta surfing concept to Substrate Integrated Waveguide (SIW) technology. It is described how this simple and versatile guiding medium can be conveniently modified and modulated to control the conversion from the conventional TE 10 propagating mode to surface or leaky wave with tailored propagation and radiation features. Theoretical aspects and practical designs are described with the general objective of wavefront control (both in amplitude and phase), showing results at Ku band (12-18 GHz) and W band (75-111 GHz), and illustrating a wide range of physical phenomena and interesting potential applications.
Yang, X., Guo, Y.J., Cui, Q., Tao, X. & Huang, X. 2012, 'Random circulant orthogonal matrix based Analog Compressed Sensing', GLOBECOM - IEEE Global Telecommunications Conference, pp. 3605-3609.
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Analog Compressed Sensing (CS) has attracted considerable research interest in sampling area. One of the promising analog CS technique is the recently proposed Modulated Wideband Converter (MWC). However, MWC has a very high hardware complexity due to its parallel structure. To reduce the hardware complexity of MWC, this paper proposes a novel Random Circulant Orthogonal Matrix based Analog Compressed Sensing (RCOM-ACS) scheme. By circularly shifting the periodic mixing function, the RCOM-ACS scheme reduces the number of physical parallel channels from m to 1 at the cost of longer processing time, where m is in the order of several dozen to several hundred in MWC. It is proved that the mM measurement matrix of RCOM-ACS scheme satisfies the Restricted Isometry Property (RIP) condition with probability 1-M -O(1) when m = O(rlog 2 Mlog 3 r), where M is the length of the periodic mixing function, r denotes the sparsity of the input signal. Furthermore, to make a good tradeoff between processing time and hardware complexity, a short processing time RCOM-ACS scheme is proposed in this paper. Simulation results show that, the proposed schemes outperform MWC in terms of recovery performance. &copy; 2012 IEEE.
Yang, X., Dutkiewicz, E., Cui, Q., Tao, X., Guo, Y.J. & Huang, X. 2012, 'Compressed network coding for distributed storage in Wireless Sensor Networks', 2012 International Symposium on Communications and Information Technologies, ISCIT 2012, pp. 816-821.
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Distributed storage plays a very important role in Wireless Sensor Networks (WSNs), especially in catastrophic scenarios. To improve the energy efficiency of distributed storage, this paper proposes a Compressed Network Coding based Distributed Storage (CNCDS) scheme. Exploiting the correlation of sensor readings and utilizing the Compressed Sensing (CS) theory and network coding technology, the proposed CNCDS scheme achieves good energy efficiency by reducing the number of transmissions and receptions. Theoretical analysis proves that, the measurement matrix of CNCDS scheme guarantees good CS recovery performance. Simulation results show that, compared with the conventional ICStorage scheme, the proposed CNCDS scheme reduces the number of transmissions, the number of receptions and the CS recovery mean squared error (MSE) by up to 55%, 74% and 76% respectively. In contrast to the conventional NICStorage scheme, the proposed CNCDS scheme can simultaneously reduce the number of transmissions, receptions and recovery MSE. &copy; 2012 IEEE.
Xu, K.C., Dutkiewicz, E., Huang, X. & Guo, Y.J. 2012, 'Ranging based positioning employing co-operative arrays', 2012 International Symposium on Communications and Information Technologies, ISCIT 2012, pp. 1055-1059.
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A novel wireless positioning method employing an array of sensors which are capable of doing range estimates is proposed. Collectively, all the sensors in the sensor array can produce the direction of arrival (DoA) and the range information of mobile targets. To improve the positioning accuracy, it is proposed to introduce co-operations between the sensor arrays. Theoretical analysis and simulation results show that the use of the co-operation can increase the positioning accuracy significantly. Compared with other known methods, the proposed method does not require any phase measurement in the sensor arrays, so the system is relatively easy to operate and maintain. &copy; 2012 IEEE.
Zhang, J., Cantoni, A., Huang, X. & Guo, Y.J. 2012, 'Sidelobe suppression with orthogonal projection for OFDM systems: Performance characterization', Communications (ICC), 2012 IEEE International Conference on, IEEE, pp. 3959-3963.
Cheng, P., Gui, L., Tao, M., Guo, Y.J., Huang, X. & Rui, Y. 2012, 'Sparse channel estimation for OFDM transmission over two-way works', IEEE International Conference on Communications, pp. 3948-3953.
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Compressed sensing (CS) has recently emerged as a powerful signal acquisition paradigm. CS enables the recovery of high-dimensional sparse signals from much fewer samples than usually required. Further, quite a few recent channel measurement experiments show that many wireless channels also tend to exhibit sparsity. In this case, CS theory can be applicable to sparse channel estimation and its effectiveness has been validated in point-to-point (P2P) communication. In this work, we study sparse channel estimation for two-way relay networks (TWRN). Unlike P2P systems, applying CS theory to sparse channel estimation in TWRN is much more challenging. One issue is that the equivalent channels (terminal-relay-terminal) may be no longer sparse due to the linear convolutional operation. On this basis, novel schemes are proposed to solve this problem and effectively improve the accuracy of TWRN channel estimation when using CS theory. Extensive numerical results are provided to corroborate the proposed studies. &copy; 2012 IEEE.
Cantoni, A., Zhang, J.A., Huang, X. & Guo, Y.J. 2012, 'Sidelobe suppression with orthogonal projection for OFDM systems', Communications Theory Workshop (AusCTW), 2012 Australian, IEEE, pp. 37-42.
Qin, P.-.Y., Ding, C. & Guo, Y.J. 2012, 'A high-gain beam-steering quasi-yagi antenna', Antennas and Propagation (ISAP), 2012 International Symposium on, IEEE, pp. 122-125.
Salman, N., Guo, Y.J., Kemp, A.H. & Ghogho, M. 2012, 'Analysis of linear least square solution for RSS based localization', 2012 International Symposium on Communications and Information Technologies, ISCIT 2012, pp. 1051-1054.
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Positioning of wireless devices has received a great deal of interest from researchers in the last decade. In order to locate nodes in low complexity and power efficient networks, the received signal strength (RSS) based positioning systems have been the center of focus. RSS based localization needs no additional hardware and hence is favored for low complexity and cheap localization networks. A major source of error in RSS location estimation is due to shadowing effects in multipath wireless channels. In this paper we analyze the performance of RSS location estimator based on the linear least square approach. We derive expressions for mean square error (MSE) and bias of location estimates. The theoretical analysis is compared with simulation results and it is observed that the analysis accurately predicts the performance of the location estimation. We also discuss the impact of reference node placement on estimation bias. &copy; 2012 IEEE.
Qin, P.-.Y., Guo, Y.J. & Dutkiewicz, E. 2012, 'Experimental analysis of a polarization reconfigurable antenna for MIMO systems', Communications and Information Technologies (ISCIT), 2012 International Symposium on, IEEE, pp. 638-642.
Guo, Y.J. 2012, 'Antenna and RF technologies for future wireless communications systems', 2012 IEEE Asia-Pacific Conference on Antennas and Propagation, APCAP 2012 - Proceedings, pp. 74-75.
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Owing to spectrum scarcity, omnipresence of interference, size restrictions and cost limitations, the proliferation of wireless communications systems has posed several major challenges to antenna and RF designers. This calls for new antenna technologies and advanced RF receivers for future systems. In this paper, research activities in wireless communications at CSIRO will be presented. In particular, we will focus on two areas, namely, reconfigurable antennas and integrated receivers employing high temperature superconducting (HTS) devices. The former would ease the demand on antenna real estate and enhance system performance. The latter would increase the sensitivity of receivers, thus enabling low power operation, greater coverage and the employment of novel interference cancellation techniques. &copy; 2012 IEEE.
Jin, R., Geng, J., Liang, X., Ye, S., Wang, W., Bird, T.S. & Guo, Y.J. 2012, 'High gain planar antenna arrays applied in mobile satellite communication (invited)', 2012 IEEE Asia-Pacific Conference on Antennas and Propagation, APCAP 2012 - Proceedings, pp. 136-137.
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Two large and low profile panel antenna arrays used as receiving and transmitting antennas for mobile satellite communications are described. The two arrays have an overall size of 12020.71.3cm 3 and 107.520.41.7cm 3 , respectively, and exhibit high gains and adequate efficiencies due to effective array designs. For the receiving panel array, a method using a number of high efficiency sub-arrays combined with a novel active integrated global feed network is proposed. For the transmitting panel array, a number of high efficiency sub-arrays together with a novel compact waveguide feed network is employed. Based on the above techniques, two large panel antenna arrays are successfully developed. We present detailed designs of the sub-arrays, the passive and active feed networks, and the vertical transitions. Simulated and experimental results show that the designed receiving and transmitting panel arrays achieve the measured gains and efficiencies of 34.1dBi, 48.2% and 33.5dBi, 36.3%, respectively, which indicates that the proposed antenna panels are good candidates for future satellite communications applications. &copy; 2012 IEEE.
Guzmán-Quirós, R., Gómez-Tornero, J.L., García-Vigueras, M., Weily, A.R. & Guo, Y.J. 2012, 'Novel topology of Fabry-Perot electronically steerable leaky-wave antenna', Proceedings of 6th European Conference on Antennas and Propagation, EuCAP 2012, pp. 224-228.
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A novel topology of electronically-steerable one-dimensional Fabry-Perot leaky-wave antenna (LWA) is proposed. The structure is based on a host parallel-plate waveguide (PPW) which encloses a Fabry-Perot cavity created by two printed-circuits boards (PCB): a top planar partially reflective surface (PRS) and a bottom tunable high impedance surface (HIS) loaded with varactors. The control of the scattering properties of the bottom tunable HIS by the variation of the varactors' capacitance enables control of the Fabry-Perot cavity resonance and thus the scanning of the antenna pointing angle from broadside towards the endfire direction at a fixed frequency. Full-wave simulations obtained with commercial finite element method solver (HFSS) demonstrate as a proof of concept a continuous scanning range of the pointing angle from 5&deg; to 50&deg; at a design frequency of 5.6 GHz. &copy; 2012 IEEE.
Sun, Z., Zhong, S.S., Esselle, K.P., Guo, J. & Cai, Y. 2012, 'Broadband dual-band dual-polarized overlapped antenna element', Proceedings of the 2012 IEEE-APS Topical Conference on Antennas and Propagation in Wireless Communications, APWC'12, pp. 223-226.
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A broadband dual-band dual-polarized (DBDP) shared-aperture array is proposed, where the novel L- and C- band overlapped stacked patches are designed as the unit cell of full array. The impedance bandwidth in the lower band is enhanced by avoiding perforation. The DBDP unit cell prototype has been fabricated to validate the overlapped-structure feasibility for phased array applications. The impedance bandwidths (|S 11 | -10dB) of 17.6% (219MHz) and 15% (790 MHz) are measured in L- and C-band, respectively, while good radiation patterns are also confirmed in both bands. &copy; 2012 IEEE.
Huang, X. & Guo, Y.J. 2011, 'Wideband AoA estimation and beamforming with hybrid antenna array', GLOBECOM - IEEE Global Telecommunications Conference.
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High speed long range millimetre-wave (mm-wave) links can be achieved by using wideband hybrid antenna arrays of sub-arrays. However, conventional wideband angle-of-arrival (AoA) estimation and beamforming algorithms are not applicable to the wideband hybrid arrays due to the array architecture difference. In this paper, an adaptive frequency-domain AoA estimation and beamforming algorithm suitable for practical wideband hybrid array of side-by-side sub-arrays is proposed. Mean square error bounds under simplified array configuration and extreme array imperfection condition are also given. Simulation results show that the proposed algorithm is robust with low complexity and fast convergence. &copy; 2011 IEEE.
Xu, K.C., Guo, Y.J., Huang, X. & Dutkiewicz, E. 2011, 'DoA based positioning employing uniform circular arrays', 11th International Symposium on Communications and Information Technologies, ISCIT 2011, pp. 328-332.
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In this paper, a methodology of employing a set of uniform circular arrays to localize the 3D position of a target in sensor networks is presented and the theoretical framework is given. Simulation results demonstrate the validity of the method and illustrate the effect of the element pattern on the accuracy of direction of arrival (DoA) estimation and positioning. A weighted least squares method (WLSM) is proposed as a means to increase the robustness of the method. &copy; 2011 IEEE.
Huang, X. & Guo, Y.J. 2011, 'Closed-form MSE performance for phase estimation from Gaussian reference signals', 11th International Symposium on Communications and Information Technologies, ISCIT 2011, pp. 154-158.
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In many communications and signal processing applications, phase information carried on Gaussian distributed reference signals is often required for various purposes, such as the carrier frequency offset estimation in orthogonal frequency division multiplexing (OFDM) systems. The performance of phase estimation is usually measured by the mean square error (MSE) which is often infeasible to obtain. Instead, the Cram&eacute;r-Rao Bound (CRB) and modified Cram&eacute;r-Rao Bound (MCRB) are used to give lower MSE bounds for the phase estimation. This paper presents closed-form MSE approximations for estimating phase information from Gaussian reference signals, which provide better indications of the MSE performance than the MCRB. It is also shown that the MCRB is only attainable at high signal-to-noise ratios and with large number of observed signal samples. Simulated and analytical results are compared to demonstrate the accuracy and efficiency of the derived MSE formulas. &copy; 2011 IEEE.
Zhang, T., Cai, Y., Du, J., Guo, Y.J. & Sun, X.W. 2011, 'A compact high-T c superconducting quarter-wavelength SIR bandpass filter', 2011 International Conference on Applied Superconductivity and Electromagnetic Devices, ASEMD 2011, pp. 123-126.
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A compact high-temperature superconducting bandpass filter for wireless communications is proposed in this paper. The filter consists of four quarter-wavelength short-circuited stepped impedance resonators (SIR). A pair of transmission zeros outside the passband are introduced into the design by evaluating coupling coefficients between the four resonators for high selectivity within the frequency band of interest. The use of short-circuited quarter-wavelength SIRs has resulted in a higher spurious passband than conventional half-wavelength coupled-line filters. Based on the theoretical calculations, the filter has a compact size and exhibits a well suppressed stopband. The filter is fabricated on an MgO substrate with YBCO superconductor coating. Simulation and measurement results are presented. &copy; 2011 IEEE.
Chan, K.Y. & Guo, Y.J. 2011, 'Analysis of RF MEMS integrated tunable high impedance surface at 60 GHz', Asia-Pacific Microwave Conference Proceedings, APMC, pp. 562-565.
This paper presents an analysis of tunable high impedance surface (HIS) integrated with RF MEMS varactors at 60 GHz. The HIS phase response with different number of RF MEMS varactors integrated with dipoles is shown. The effect of shifting RF MEMS varactors across the proposed dipoles and patches are highlighted. This paper provides a guideline for designing HIS integrated with RF MEMS varactors. It illustrates the significance of RF MEMS varactor location versus HIS phase response. &copy; 2011 Engineers Australia.
Yang, Y., Cai, Y., Chan, K.Y., Ramer, R. & Guo, Y.J. 2011, 'MEMS-loaded millimeter wave frequency reconfigurable quasi-Yagi dipole antenna', Asia-Pacific Microwave Conference Proceedings, APMC, pp. 1318-1321.
A new millimeter-wave frequency reconfigurable quasi-Yagi antenna is presented. The quasi-Yagi antenna is printed on a quartz substrate integrated with RF MEMS switches. It consists of one driven dipole, two dipole directors, and one truncated ground plane as reflector. By controlling the actuation of the RF MEMS loaded on the driven and director dipole elements, the antenna operation frequency is switchable in the millimeter wave wireless personal area network (WPAN) band (57-66 GHz) and E-band (71-86 GHz). The end-fire pattern of the Yagi-antenna is maintained in both two-bands. Theoretical results show that the antenna gain varies from 5.5 to 6.7 dBi in the lower band and from 6.5 dBi to 8.1 dBi in the higher band respectively. A high resistive biasing line configuration is presented and its effect on the antenna reflection coefficient is investigated. &copy; 2011 Engineers Australia.
Qin, P.-.Y., Guo, Y.J. & Dutkiewicz, E. 2011, 'Capacity enhancement of 2$\times$ 2 MIMO system using pattern reconfigurable antennas', Microwave Conference Proceedings (APMC), 2011 Asia-Pacific, IEEE, pp. 1694-1697.
Cai, Y., Guo, Y.J. & Qin, P. 2011, 'Frequency switchable quasi-Yagi dipole array for base station antennas', Antennas and Propagation (APSURSI), 2011 IEEE International Symposium on, IEEE, pp. 738-741.
Cai, Y. & Jay Guo, Y. 2011, 'A reconfigurable decoupling and matching network for a frequency agile compact array', Proceedings of the 5th European Conference on Antennas and Propagation, EUCAP 2011, pp. 896-899.
A novel frequency reconfigurable compact array incorporating a reconfigurable decoupling and matching network (DMN) is proposed. The array radiating part consists of two printed monopole antennas. An inductive biasing line is devised to control the PIN diode states so that the array operating frequency is switchable between 2.5 and 3.5 GHz bands. The element spacing is chosen to be as small as 0.05 0 at 2.5GHz, which leads to a strong mutual coupling between antenna ports. A reconfigurable DMN is proposed to mitigate the mutual coupling effect for both 2.5 and 3.5GHz bands. Simulation results show that the use of the DMN realizes a well matched (S 11 < = -10dB) and decoupled (S 21 < = -20dB) bandwidth of 70MHz and 120MHz in the lower and higher bands, respectively. The antenna total efficiency can be substantially affected by the internal resistor when the PIN diodes are in the ON state. The compact size and frequency reconfigurability feature greatly save the antenna real estate. The decoupled array can be useful for a multi-input multi-output (MIMO) diversity system. &copy; 2011 EurAAP.
Huang, X., Dyadyuk, V., Guo, Y.J., Stokes, L. & Pathikulangara, J. 2010, 'Frequency-domain digital calibration and beamforming with wideband antenna array', GLOBECOM - IEEE Global Telecommunications Conference.
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This paper presents a joint channel and mutual coupling estimation technique for wideband antenna array to achieve high speed wireless communications in the millimetrewave frequency bands. The estimated channel frequency responses and mutual coupling matrix can be used to digitally calibrate a wideband antenna array in the frequency-domain, followed by digital beamforming. Experiments are carried out using a four-element receive array prototype in the E-band (71-76 GHz) to demonstrate the frequency-domain digital calibration and beamforming performance. The results show that both the mutual coupling and wideband effects are effectively mitigated by the proposed technique and a 11.5 dBi array gain is achieved which is very close to that of an ideal four-element antenna array. &copy;2010 IEEE.
Zhou, E., Shi, J., Li, Y., Vucetic, B., Huang, X. & Guo, Y.J. 2010, 'Power allocation based on truncated squared norm of channel equalization coefficients for TDD LTE-A uplink systems', IEEE Wireless Communications and Networking Conference, WCNC.
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The power allocation problem is addressed for time division duplex (TDD) LTE-A uplink systems in this paper. Due to the IDFT de-spreading in LTE-A uplink, the channel frequency responses in an IDFT de-spreading block will be tangled together. After analyzing the equivalent signal to interference plus noise ratio (SINR) in the time domain, a Truncated Squared norm of channel equalization Coefficients based Power Allocation (TSCPA) method is proposed to improve the final SINR performance after the IDFT de-spreading block. The proposed TSC-PA algorithm is verified for the clustered DFT-s-OFDM system in eigen-model block diagonalization multi-user MIMO uplink environment by simulations. The results demonstrate that the proposed TSC-PA algorithm can further improve the system block error rate (BLER) performance by selecting a proper truncation threshold. &copy;2010 IEEE.
Su, Y., Tang, S., Shi, J., Huang, X. & Guo, Y.J. 2010, 'Robust downlink precoding in multiuser MIMO-OFDM systems with time-domain quantized feedback', IEEE Wireless Communications and Networking Conference, WCNC.
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We consider the robust linear precoding (LP) and Tomlinson-Harashima precoding (THP) schemes for multiuser MIMO-OFDM downlink channels with limited feedback. Benefiting from the correlation of spatial channels, the mobile terminal compresses and feeds back the time-domain channel vectors instead of the corresponding frequency-domain vectors to substantially reduce the feedback signalling overhead. A compression and restoration method and a codebook design for channel state information at the transmitter (CSIT) feedback are proposed in the time domain. By treating the partial CSIT as a random quantity, we develop the robust precoders to combat the truncation and quantization errors introduced in the feedback procedure. In comparison with the non-robust designs, both the robust LP and THP have better bit-error rate performance especially in high signal-to-noise ratio region. &copy;2010 IEEE.
Huang, X. & Guo, Y.J. 2010, 'MSE lower bounds for phase estimation based on overlapped Gaussian distribution', ISCIT 2010 - 2010 10th International Symposium on Communications and Information Technologies, pp. 655-660.
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The Cram&eacute;r-Rao bound (CRB) has been widely used as a mean square error (MSE) lower bound for unbiased parameter estimations. For phase estimation, however, the CRB is not valid at low signal-to-noise ratio (SNR) due to the effect of phase wrapping. In this paper, closed-form approximations of the MSE lower bounds for the phase estimation are derived under both Gaussian and Rayleigh fading channels, which are particularly useful at low SNR. The derivation is based on an overlapped Gaussian distribution which is used to approximate the true posterior phase distribution. Analytical and simulation results show that the derived closed-form MSE lower bounds provide more meaningful indications to the phase estimation performance than the CRB. &copy;2010 IEEE.
Huang, X. & Guo, Y.J. 2010, 'Block spread OFDMA with STC MIMO for improved frequency and spatial diversity over broadband wireless access uplink', IEEE Wireless Communications and Networking Conference, WCNC.
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A novel combination of block spread orthogonal frequency division multiple access (BS-OFDMA) with space-time coded multiple input multiple output (STC MIMO) scheme is proposed for broadband wireless access uplink transmission. Using complex exponential spreading sequences, the block spreading technique can efficiently generate precoded OFDMA signal to exploit frequency diversity. An Alamouti STC MIMO encoding technique is incorporated with the block spreading to achieve further spatial diversity. The performance of the proposed STC-BS-OFDMA system using minimum mean squared error equalization is analyzed, and a closed-form asymptotical bit error rate expression is derived. Simulation results are also given to demonstrate the improved diversity performance as compared with other OFDMA schemes. The proposed techniques are well suited for future broadband wireless access systems such as 3G LTE and 4G. &copy;2010 IEEE.
Tornero, J.L.G., Weily, A.R. & Guo, Y.J. 2010, 'Non-standard tapering of leaky-wave antennas in hybrid technology', 2010 IEEE International Symposium on Antennas and Propagation and CNC-USNC/URSI Radio Science Meeting - Leading the Wave, AP-S/URSI 2010.
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This paper illustrates for the first time the ability of leaky-wave antennas (LWAs) [1] in hybrid waveguide printed-circuit technology [2] to provide non-standard simultaneous tapering of the phase and the leakage rate of the constituent leakymode. This unusual tapering allows synthesis of broadbeam radiation patterns with high rejection out of the prescribed beamwidth [3], high efficiency focusing near field patterns [3,4] , or highly directive conformal antennas [5]. The proposed hybrid technology offers a much simpler and more flexible mechanism to design this unusual type of tapered LWAs, if compared to LWAs in pure waveguide [3] or pure printed-circuit [4-5] technologies. &copy; 2010 IEEE.
Cai, Y. & Guo, Y.J. 2010, 'Dipole uniform circular array backed by a cylindrical reflector', EuCAP 2010 - The 4th European Conference on Antennas and Propagation.
A 12-element thin dipole uniform circular array (UCA) is studied using the Method of Moments. The effect of metallic back reflectors on the array performance, in terms of the maximum realized gain, the mutual coupling level, and the synthesized patterns, is investigated. Over the inter-element spacing range, 0.3 0 d 0.7 0 , simulation results show that the introduction of the cylindrical reflector achieves at least 1.0dB higher the gain than the one without using the reflector. Radial metallic 'partition walls' is proposed to be placed between axially oriented dipoles. The use of the 'partition walls' realizes further gain enhancement and H-plane mutual coupling reduction. At d = 0.4 0 and d = 0.6 0 , maximum coupling between elements is suppressed to a level below -13dB and -20dB respectively when the height of the 'partition walls', h wall , is greater than 0.175 0 . In the synthesized realized gain pattern, mainlobe to sidelobe ratio better than 15dB and 13dB is obtained.
Qin, P.-.Y., Weily, A.R., Guo, Y.J. & Liang, C.-.H. 2010, 'Millimeter wave frequency reconfigurable quasi-Yagi antenna', Microwave Conference Proceedings (APMC), 2010 Asia-Pacific, IEEE, pp. 642-645.
Xu, K.C., Guo, Y.J. & Dutkiewicz, E. 2010, 'Swimmer tracking with underwater acoustic networks', ISCIT 2010 - 2010 10th International Symposium on Communications and Information Technologies, pp. 1045-1049.
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A scheme for positioning swimmers using underwater acoustic networks is proposed. The design and the performance of such a network are presented. Owing to its high accuracy, the spherical interpolation approach is employed as the positioning algorithm. The configuration of the network, namely, the arrangement of anchor nodes in the swimming pool, is optimized to achieve the highest accuracy with the minimum number of nodes and therefore the lowest cost. The simulation study includes both two dimensional (2D) and three dimensional (3D) cases in order to understand the variation of positioning estimation accuracy in horizontal and vertical directions. &copy;2010 IEEE.
Qin, P.Y., Weily, A.R., Guo, Y.J., Liang, C.H. & Cai, Y. 2010, 'A pattern reconfigurable U-slot patch antenna', Antennas and Propagation Society International Symposium (APSURSI), 2010 IEEE, IEEE, pp. 1-4.
Shafi, M. & Guo, Y.J. 2010, 'Welcome message from the IEEE WCNC 2010 TPC chairs', IEEE Wireless Communications and Networking Conference, WCNC.
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Cai, Y., Jay Guo, Y., Qin, P.Y. & Weily, A.R. 2010, 'Frequency reconfigurable quasi-Yagi dipole antenna', 2010 IEEE International Symposium on Antennas and Propagation and CNC-USNC/URSI Radio Science Meeting - Leading the Wave, AP-S/URSI 2010.
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A frequency reconfigurable quasi-Yagi dipole antenna is presented in this paper. Simulation results show that a 35% continuously tuning impedance bandwidth, from 1.85 to 2.5GHz, is obtained. Loaded with varactor diodes, the effective electrical lengths of the driver and director dipoles are varied by changing the biasing voltages. The length adjustable director allows the endfire pattern with relatively high gain being maintained over each tuning sub-band. Across the tuning bandwidth, the predicted gain variation is from 5.8dBi to 7.9dBi. The H-plane cross-polarization level is below -17dB while this value is below -32dB in the E-plane. The front-to-back ratio is better than 12dB. &copy; 2010 IEEE.
Nikolic, N., Weily, A.R., James, G.L., Greene, K., Barker, S. & Jay Guo, Y. 2010, 'Reduction of the grating lobes in Luneburg lens arrays', 2010 IEEE International Symposium on Antennas and Propagation and CNC-USNC/URSI Radio Science Meeting - Leading the Wave, AP-S/URSI 2010.
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Mobile satellite communication systems suitable for installation on moving vehicles are increasingly in demand [1]-[3] . One of the main requirements for such systems is low-profile in order to prevent intolerable drag and air-stream turbulence. A low profile Ku-band antenna system based on a four-element Luneburg lens array (LLA) was presented in [3] where the reduction in height is achieved by using a ground plane and by increasing the number of elements at the expense of increased diameter of the array. However, using an array of elements has an inherent problem of grating lobes [4] . This problem is particularly difficult in an array of lenses since the minimum array spacing is limited by the lens size and generally it is of the order of several wavelengths. High grating lobes in the radiation pattern limit the usefulness of the lens array and their reduction is critical. So far, the results for the expected grating lobes in an array of Luneburg lenses have not been reported in the literature. Our aim is to study the grating lobes in a LLA as a function of the number of lenses in the array and also as a function of the spacing between the lenses. We present simulated results for the radiation patterns of two arrays using three and four Luneburg lenses, respectively, and show how removing part of the outer shells of the Luneburg lens and decreasing the element spacing can reduce the grating lobe level. &copy; 2010 IEEE.
Huang, X., Guo, Y.J. & Bunton, J. 2009, 'Adaptive AoA estimation and beamforming with hybrid antenna arrays', IEEE Vehicular Technology Conference.
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A new type of hybrid antenna array consisting of analogue subarrays followed by a digital beamformer is proposed for practical implementation of long range high data rate millimetre wave communications systems. An adaptive algorithm, referred to as the differential beam search (DBS), is proposed for the angle of arrival (AoA) estimation to control the phase shifters in the analogue subarrays and to perform digital beamforming. This algorithm does not need the knowledge of a reference signal and effectively solves the phase ambiguity problem in AoA estimation inherent to the practical subarray configuration. The performance of the proposed DBS algorithms is demonstrated by simulations. &copy; 2009 IEEE.
Huang, X. & Guo, Y.J. 2009, 'Parallel packet transmission based on OFDM', IEEE Wireless Communications and Networking Conference, WCNC.
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This paper proposes a parallel packet transmission (PPT) scheme based on orthogonal frequency division multiplexing (OFDM). The principle of the PPT scheme is to divide a packet into a number of smaller parallel packets, and transmit each smaller packet over an individual subcarrier of the OFDM symbols instead of spreading the data bits in a packet across a number of different subcarriers. It is proved theoretically that the proposed PPT scheme has higher average throughput than the conventional serial packet transmission without precoding. Furthermore, simulation results show that the OFDM system with PPT outperforms the precoded OFDM system with minimum mean squared error equalization in both uncoded and coded cases in terms of average throughput. The PPT scheme provides an alternative and simpler means to combat frequency-selective fading. &copy; 2009 IEEE.
Huang, X. & Guo, Y.J. 2009, 'MSE bounds for phase estimation in presence of recursive nuisance parameters', GLOBECOM - IEEE Global Telecommunications Conference.
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The mean squared error (MSE) is commonly used to measure and compare the performance of various phase estimation techniques in communications and signal processing systems. When the received signal contains recursive nuisance parameters, the MSE is extremely difficult to obtain and even the conventional modified Cram&eacute;r-Rao bound (MCRB) can not be readily applied. In this paper, a recursive MSE bound and its simplified calculation method are proposed to solve the problem. As an application example, an adaptive hybrid antenna array and its associated angle-of-arrival (AoA) estimation technique are presented. The MSE of the AoA estimation is simulated and compared with the recursive MSE bound and MCRB. The results show that the proposed recursive MSE bound provides a tighter lower MSE bound than the recursive MCRB.
Huang, X. & Guo, Y.J. 2009, 'Frequency and space precoded MIMO OFDM with substream adaptation', IEEE Wireless Communications and Networking Conference, WCNC.
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A new frequency and space precoding scheme for multiple input multiple output (MIMO) orthogonal frequency division multiplexing (OFDM) systems is presented. For frequency precoding, the data symbols to be transmitted are divided into multiple substreams, and a predefined unitary matrix is applied to each substream to obtain different linear combinations of data symbols in the substream to gain frequency diversity. For space precoding, different precoding matrices selected from a predefined orthogonal matrix are used to allocate each frequency precoded data symbol to all transmit antennas to gain spatial diversity. The number of substreams and the corresponding data symbol mapping scheme are also adaptively determined at the receiver under varying received signal strength and MIMO channel conditions, and are made available to the transmitter through a low-rate feedback channel. Simulation results show that the proposed MIMO OFDM system with adaptive substream selection can effectively exploit both frequency and spatial diversity, and deliver the maximum system throughput. &copy; 2009 IEEE.
Dyadyuk, V., Guo, Y.J. & Bunton, J.D. 2009, 'Multi-gigabit wireless communication technology in the E-band', Proceedings of the 2009 1st International Conference on Wireless Communication, Vehicular Technology, Information Theory and Aerospace and Electronic Systems Technology, Wireless VITAE 2009, pp. 137-141.
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The enabling technologies and challenges in development of multi-gigabit wireless communication systems in the E-band are discussed. Potentials of the further improvement of the fixed wireless links performance and feasibility of development of the future ad-hoc or mobile wireless networks in the E-band are evaluated. &copy; 2009 IEEE.
Dyadyuk, V., Bunton, J.D. & Guo, Y.J. 2009, 'Study on high rate long range wireless communications in the 71-76 and 81-86 GHz bands', European Microwave Week 2009, EuMW 2009: Science, Progress and Quality at Radiofrequencies, Conference Proceedings - 39th European Microwave Conference, EuMC 2009, pp. 1315-1318.
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Performance of high data rate wireless line-of-sight communications in the E-band is analysed using an example of the spectrally efficient multi-gigabit system reported earlier. This paper discussed available technologies, potentials of a further increase of the communication range and challenges in development of the future multi-gigabit wireless networks. &copy; 2009 EuMA.
Qin, P.Y., Weily, A.R., Guo, Y.J. & Liang, C.H. 2009, 'A reconfigurable quasi-Yagi folded dipole antenna', Antennas and Propagation Society International Symposium, 2009. APSURSI'09. IEEE, IEEE, pp. 1-4.
Qin, P.Y., Weily, A.R., Guo, Y.J. & Liang, C.H. 2009, 'A Reconfigurable Quasi-Yagi Folded Dipole Antenna', 2009 IEEE ANTENNAS AND PROPAGATION SOCIETY INTERNATIONAL SYMPOSIUM AND USNC/URSI NATIONAL RADIO SCIENCE MEETING, VOLS 1-6, IEEE Antennas and Propagation International Symposium /USNC/URSI National Radio Science Meeting, IEEE, N Charleston, SC, pp. 2092-+.
Dyadyuk, V., Guo, Y.J. & Bunton, J.D. 2009, 'Multi-Gigabit Wireless Communication Technology in the E-band', 2009 1ST INTERNATIONAL CONFERENCE ON WIRELESS COMMUNICATION, VEHICULAR TECHNOLOGY, INFORMATION THEORY AND AEROSPACE & ELECTRONIC SYSTEMS TECHNOLOGY, VOLS 1 AND 2, 1st International Conference on Wireless Communication, Vehicular Technology, Information Theory and Aerospace and Electronic Systems Technology, IEEE, Aalborg, DENMARK, pp. 142-146.
Yu, K. & Guo, Y.J. 2008, 'Improving anchor position accuracy for 3-D localization in wireless sensor networks', IEEE International Conference on Communications, pp. 951-955.
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Accuracy of ordinary sensor node localization in wireless sensor networks mainly depends on the signal parameter such as time-of-arrival and signal strength estimation errors and the accuracy of the anchor node locations. In this paper a low-complexity but efficient algorithm is derived to improve anchor location accuracy in the presence of both anchor-to-anchor distance and AOA estimates and GPS measurements. Also, a Lenvenberg-Marquardt (LM) optimization based algorithm is developed for accuracy improvement when anchor-to-anchor distance estimates and GPS measurements are provided. Further, we derive the Cramer-Rao lower bound (CRLB) to benchmark the anchor position accuracy. To our knowledge, improving anchor node location accuracy and deriving the CRLB in the presence of both GPS and anchor-to-anchor measurements in 3-D scenarios are not reported in the literature. Simulation results demonstrate that the proposed approaches can improve the anchor position accuracy substantially and that the accuracy of the two developed algorithms approaches the corresponding CRLB. &copy;2008 IEEE.
Yu, K. & Guo, Y.J. 2008, 'Non-line-of-sight detection based on TOA and signal strength', IEEE International Symposium on Personal, Indoor and Mobile Radio Communications, PIMRC.
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This paper addresses the problem of identifying NLOS propagation by applying the statistical decision theory. A time-of-arrival (TOA) based method is developed under idealized conditions to provide a performance reference. In the presence of both TOA and received signal strength (RSS) measurements, a joint identification method is derived to efficiently exploit both the TOA and RSS measurements. Analytical expressions for the probability of detection (POD) and the probability of false alarm (PFA) are derived. Simulation results demonstrate that the proposed methods perform well and the joint TOA and RSS based method outperforms the TOA based methods considerably. It is also shown that the analytical results agree with the simulated ones. &copy; 2008 IEEE.
Sharp, I., Yu, K. & Guo, Y.J. 2008, 'Performance analysis of bandlimited TOA estimation using peak tracking', IEEE Vehicular Technology Conference.
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This paper presents the performance analysis of time-of-arrival (TOA) measurements by employing bandlimited radio signals. We choose one of the practical TOA estimation methods, peak tracking for study. First, two simplified models, i.e. the hyperbolic and Gaussian models are introduced to approximate the correlation diagram (correlogram) for ease of performance analysis. It is shown that the two models accurately approximate the true bandlimited correlogram especially around the peak. Concise expressions of the TOA estimation errors are derived for either Gaussian measurement noise or multipath interference when using bandlimited signals. The analytical results can be readily exploited to assist the design of TOA based positioning systems using peak tracking algorithm under bandwidth constraints. &copy;2008 IEEE.
Yu, K. & Guo, Y.J. 2008, 'Robust localization in multihop wireless sensor networks', IEEE Vehicular Technology Conference, pp. 2819-2823.
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In this paper a hybrid localization scheme for multihop wireless sensor networks is presented. At first a relatively dense group of nodes is selected as a base. Next, the multidimensional scaling (MDS) method is applied to localize the group of nodes. Then, the robust quads (RQ) method is employed to localize other nodes, following which we make use of the robust triangle and radio range (RTRR) approach to perform the localization task. The RQ and the RTRR methods are used alternately until no more nodes can be localized by the two approaches. Simulation results demonstrate that the proposed hybrid localization algorithm performs well in terms of both accuracy and success rate of localization. &copy; 2008 IEEE.
Li, Y., Li, L., Hellicar, A. & Guo, Y.J. 2008, 'Super-resolution reconstruction of terahertz images', Proceedings of SPIE - The International Society for Optical Engineering.
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A prototype of terahertz imaging system has been built in CSIRO. This imager uses a backward wave oscillator as the source and a Schottky diode as the detector. It has a bandwidth of 500-700 GHz and a source power 10 mW. The resolution at 610 GHz is about 0.85 mm. Even though this imaging system is a coherent system, only the signal power is measured at the detector and the phase information of the detected wave is lost. Some initial images of tree leaves, chocolate bars and pinholes have been acquired with this system. In this paper, we report experimental results of an attempt to improve the resolution of this imaging system beyond the limitation of diffraction (super-resolution). Due to the lack of phase information needed for applying any coherent super-resolution algorithms, the performance of the incoherent Richardson-Lucy super-resolution algorithm has been evaluated. Experimental results have demonstrated that the Richardson-Lucy algorithm can significantly improve the resolution of these images in some sample areas and produce some artifacts in other areas. These experimental results are analyzed and discussed.
Yu, K., Jay Guo, Y. & Oppermann, I. 2008, 'Modified taylor series expansion based positioning algorithms', IEEE Vehicular Technology Conference, pp. 2656-2660.
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In this paper, we propose a modified two stage Taylor series (TS) method for position estimation in a 3-D environment when either the time-difference-of-arrival (TDOA) or the distance measurements are available. It is aimed to improve the convergence performance of the traditional Taylor series method. Simulation results demonstrate that the modified TS method can improve the position estimation convergence considerably. &copy; 2008 IEEE.
Yu, K. & Guo, Y.J. 2007, 'NLOS error mitigation for mobile location estimation in wireless networks', IEEE Vehicular Technology Conference, pp. 1071-1075.
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Most radio positioning methods are based on the measurements of distance between different wireless nodes. Owing to the existence of non-line-of-sight (NLOS) radio propagation, unfortunately, not all the measured distances are reliable. One way to tackle the problem of positioning is therefore to take two-steps: (i) identifying the NLOS measurements; (ii) smart signal processing of the mixed LOS and NLOS measurements. This paper is focused on the second issue. Under the assumption that the NLOS measurements have been identified, we first propose a simple method to suppress the effect of the NLOS error. Simulation results demonstrate that the proposed method achieves similar or better accuracy than several other known methods and the computational complexity is reduced considerably. We also present an optimal location estimator under the assumption of Gaussian distributed measurement noise and Rayleigh distributed NLOS error. Although it is difficult to achieve the optimal performance in practice due to modeling uncertainties, the optimal estimator provides a performance benchmark. &copy; 2007 IEEE.
Zhou, S., Liu, R.P. & Guo, Y.J. 2007, 'Energy efficient networking protocols for wireless sensor networks', 2006 IEEE International Conference on Industrial Informatics, INDIN'06, pp. 1006-1011.
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Energy efficiency is widely regarded as one of the major challenges for wireless sensor networks. In the literature, the issue is normally addressed from the viewpoint of a specific protocol layer or functionality, such as medium access control (MAC) or routing. In this paper, energy conservation in wireless sensor networks is treated with a holistic approach and examined across all protocol layers and functionalities including MAC, topology management, routing and sensor protocols. The advantages and disadvantages of different protocols for different layers are reviewed and discussed. Some recommendations on the employment of protocols for small, medium and large scale wireless sensor networks are presented. &copy; 2006 IEEE.
Yu, K., Hedley, M., Sharp, I. & Guo, Y.J. 2007, 'Node positioning in ad hoc wireless sensor networks', 2006 IEEE International Conference on Industrial Informatics, INDIN'06, pp. 641-646.
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Locating the sensor nodes in an ad hoc wireless sensor network (WSN) is a very challenging task. In general, the network nodes are not synchronised and the internal delays within the sensor nodes may be unknown. As a result, the positioning problem can not be solved by simply using the triangulation method and certain prior information must be provided. In this paper, we consider a scenario where there are a number of nodes whose positions are known, and it is required to locate the other mobile or static sensor nodes within the radio range of each other by measuring the time of arrival (TOA) in the whole system. Two algorithms are employed, the direct method and the linear least squares (LS) estimator. The performance of the two algorithms is investigated. In particular an analytical formula is derived to estimate the performance of the LS estimator. Simulation results agree well with theoretical predictions. &copy; 2006 IEEE.
Li, Y., Archer, J.W., Rosolen, G., Hay, S.G., Timms, G.P. & Guo, Y.J. 2007, 'Fringe management for a T-shaped millimeter-wave imaging system', IEEE Transactions on Microwave Theory and Techniques, pp. 1246-1253.
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Two methods, the modulated scene method and modulated beam method, are proposed in this paper to manage the fringe in a T-shaped correlating millimeter-wave imaging system. The modulated scene method incorporates the fringe into the scene to form a fringe-modulated scene. The pencil beam that corresponds to the beam of the system with a zero baseline scans the modulated scene to form an image. To recover the image of the original scene, an algorithm that involves demodulation and spectrum patching is used to process the original image after deconvolution. The resulting image is a super-resolution image of the scene. The advantage of the modulated scene method is that a phase shifter is not required. The modulated beam method incorporates the fringe into the beam. By dynamically adjusting the phase of a local oscillator, the fringe scans together with the beam. The advantages of this method are that demodulation is unnecessary and only a single output (real or imaginary) from the complex correlator is necessary to generate a super-resolution image. A disadvantage is that a rapidly adjustable phase shifter is needed. The performance of these methods is theoretically analyzed and tested with simulated data. &copy; 2007 IEEE.
Weily, A.R. & Guo, Y.J. 2007, 'An aperture coupled patch antenna system with MEMS-based reconfigurable polarization', ISCIT 2007 - 2007 International Symposium on Communications and Information Technologies Proceedings, pp. 325-328.
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An aperture coupled patch antenna suitable for IEEE 802.11b/g WLAN applications is described. The antenna system enables the polarization of the device to be dynamically reconfigured, where the reconfiguration is actuated by an RF microelectromechanical system (MEMS) single-pole double-throw (SPDT) switch. An equivalent circuit model of the RF MEMS switch is used In the electromagnetic simulations of the antenna. This enables an accurate analysis of the antenna cross-polarization, which is highly dependent on the switch isolation. Theoretical results are given for the return loss, radiation patterns and gain of the antenna In both vertical and horizontal polarization states. &copy; 2007 IEEE.
Yu, K. & Guo, Y.J. 2007, 'Efficient location estimators in NLOS environments', IEEE International Symposium on Personal, Indoor and Mobile Radio Communications, PIMRC.
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In the paper we consider location estimation in an non-line-of-sight (NLOS) environment. A constrained optimization based location algorithm is proposed to jointly estimate the unknown location and bias by using the sequential quadratic programming (SQP) algorithm. This method does not rely on any prior statistics information, and simulation results show that the proposed method outperforms the existing related methods considerably. To reduce the complexity of the SQP based algorithm, we further propose a Taylor-series expansion based linear quadratic programming (TS-LQP) algorithm. Simulation results demonstrate that the computational complexity of the TS-LQP algorithm is only a fraction of that of the SQP algorithm while the accuracy loss is marginal. &copy; 2007 IEEE.
Li, Y., Timms, G., Archer, J., Rosolen, G., Tello, J., Brothers, M., Hellicar, A. & Guo, Y.J. 2007, 'Passive mm-wave imaging using two scanning fan-beam antennas', Proceedings of SPIE - The International Society for Optical Engineering.
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A prototype cross-correlating 190 GHz passive mm-wave imaging system has been developed. This system is based on the Mills Cross system used for radio astronomical imaging. It uses two pillbox antennas arranged in a T configuration. Each antenna generates a fan beam and the two fan beams are orthogonal to each other. By cross-correlating signals received from the two antennas, an output is obtained which is proportional to the millimeter-wave intensity radiated from the target at the intersection of the two fan beams. Beam scanning is generated by rotating a small sub-reflector inside each antenna. As a result, these relatively heavy antennas are stable during scanning and a high frame rate can be achieved. Another advantage of this approach is that only two receivers are required. The baseline (the displacement between phase centers of the two antennas) of this system is not zero, because the phase centers of the two antennas are not located at the same position. The baseline generates a fringe in the imaging system and its influence on the performance of the system is analyzed in this paper. The scanning speed of this system is also much faster than that of the Mills Cross imaging system and its influence on the resolution is also analyzed. It is found that the effect of the scanning speed is minimized when the beam scans along the equal-phase line of the fringe. This system can also be used as an active imaging system and this is discussed in another paper.
Jay Guo, Y. 2007, 'Message from technical program chair', ISCIT 2007 - 2007 International Symposium on Communications and Information Technologies Proceedings.
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Platt, G., Jones, T., James, G. & Guo, Y. 2006, 'Distributed energy management and control- Experiences in Australia', 41st International Conference on Large High Voltage Electric Systems 2006, CIGRE 2006.
This paper describes CSIRO's research and deployment work in technologies for the management and control of distributed energy devices. This work is designed to provide real-time, two-way communication and decision making between distributed energy (DE) resources- loads and generators- in electricity distribution networks. The general DE management and control concept is based on a decentralised architecture, which is a significant shift from the control architectures normally employed in electrical distribution systems. This architecture has a number of advantages, including scalability, improved economics of installation, inherent reliability by removing central points of failure, and improved granularity of data gathering and control functions. The applications of our decentralised management and control architecture are many, but include improving grid reliability, allowing consumers to play a more active role in their energy usage, and benefiting the network by alleviating the effects of peak wholesale prices and network constraints. The technology is aimed deployment in the Australian National Electricity Market within the next five years, and this paper details our latest work in this area. It includes a discussion of CSIRO's theoretical and simulation research efforts into multi-agent distributed systems, whilst also detailing work trialling the distributed energy management and control system in a real-world context.
Guo, Y.J., Vadgama, S., Davies, M., Khalab, J., Zarri, M. & Spink, D. 1998, 'Adaptive antenna for CDMA', IEEE International Symposium on Spread Spectrum Techniques & Applications, pp. 590-594.
A decision directed adaptive antenna array for the uplink of CDMA cellular systems, which is based on a normalized least mean square algorithm (NLMS), is presented. The bit error ratio performance of the adaptive antenna in various scenarios, which include the use of transmission power control (TPC) and diversity combining, is studied. It is shown that the adaptive antenna outperforms the steering beam technique when the signal-to-noise ratio is large and the active users are clustered. However, the performance of the adaptive antenna becomes very similar to that of the steering beam when there are a large number of randomly distributed active users in the sector.
Tellambura, C., Parker, M.G. & Barton, S.K. 1998, 'Channel estimation using discrete Fourier transform techniques', GLOBECOM 98: IEEE GLOBECOM 1998 - CONFERENCE RECORD, VOLS 1-6, IEEE Global Telecommunications Conference (GLOBECOM 98), IEEE, SYDNEY, AUSTRALIA, pp. 148-152.
Ince, E.A., Guo, Y.J. & Barton, S.K. 1997, 'T-algorithm detection of partial response continuous phase modulated signals over multipath channels', IEEE International Symposium on Personal, Indoor and Mobile Radio Communications, PIMRC, pp. 1135-1139.
This paper presents a new approach to reduced complexity detection of partial response continuous phase modulated signals over channels with severe intersymbol interference (ISI). The detector combines the overall channel response for the CPM modulator with that of a multipath channel to calculate the branch metrics of a breadth-first sequential detection algorithm known as the T-algorithm. To our knowledge the reported work is the first attempt to make use of such a technique for equalization of quaternary partial response CPM signals transmitted over multipath channels. Simulation of the performance of the receiver in multipath channels is reported.
Tellambura, C., Guo, Y.J. & Barton, S.K. 1997, 'Noniterative approach for computing linear equaliser tap weights', IEEE International Symposium on Personal, Indoor and Mobile Radio Communications, PIMRC, pp. 302-306.
A fast computation method for the tap weights of a linear equaliser is developed. By approximating the channel autocorrelation matrix, which has a Toeplitz structure, by a circulant matrix, the tap weights can be solved via discrete fourier transform (DFT) techniques. For an equaliser with N taps, the approximate tap weights approach the exact tap weights as N . Excess mean-square error and bit error rate (BER) degradation caused by the approximate tap weights are computed for a representative channel.
Guerin, S., Guo, Y.J. & Barton, S.K. 1997, 'Indoor propagation measurements at 5 GHz for HIPERLAN', IEE Conference Publication.
Indoor propagation measurements for HIPERLAN at 5 GHz are reported. Using two patch antennas designed for HIPERLAN, one being fixed at the ceiling of a meeting room and the other being moved around in the room, the path loss, delay profiles and delay parameters are obtained. The effect of multiple reflection is demonstrated by the direction of arrival (DOA) measurements.
Tellambura, C., Johnson, I.R., Guo, Y.J. & Barton, S.K. 1997, 'Equalization and frequency offset correction for HIPERLAN', IEEE International Symposium on Personal, Indoor and Mobile Radio Communications, PIMRC, pp. 796-800.
To reduce the effects of inter-symbol interference resulting from the dispersive nature of the indoor radio channel most HIPERLAN receivers will incorporate an adaptive equalizer. In this paper, computational complexity of several equalizer algorithms is estimated. The effect of frequency offset between transmitter and receiver on the performance of such an equalizer is investigated. By employing a decision feedback equalizer incorporating a second order phase locked loop, the effect of both the intersymbol interference and frequency offset can be significantly reduced. Using such a technique, the packet error ratio (PER) of a HIPERLAN radio link in a multipath channel is found by simulation.
Ince, E.A., Vorizanakis, N., Guo, Y.J. & Barton, S.K. 1997, 'Breadth-first sequential detection of PR-CPM signals over AWGN and multipath channels', IEEE International Symposium on Information Theory - Proceedings, p. 496.
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Detection of partial response continuous phase modulated signals over AWGN and multipath channels is presented. The receiver uses a breadth-first sequential detection algorithm known as the M-algorithm (MA). Compared with the maximum likelihood receiver based on the Viterbi algorithm (VA), a significant reduction in complexity is obtained in the proposed receiver while maintaining good performance. &copy; 1997 IEEE.
Alkussayer, H.M., Zheng, F.C., Guo, Y.J. & Barton, S.K. 1996, 'Time diversity decorrelator (TDD); a near-far resistant detector for asynchronous CDMA system', IEEE Vehicular Technology Conference, pp. 564-568.
In this paper a near-far resistance detector for asynchronous Code-Division Multiple-Access (CDMA) systems operating in Additive White Gaussian Noise (AWGN) channels is presented. The multi-user interference caused by K users transmitting simultaneously, each with a specific signature sequence, is completely removed at the receiver. The complexity of this detector grows only linearly with the number of users, as compared to the optimum multi-user detector which requires exponential complexity in the number of users. A modified algorithm based on time diversity is described. It performs detection on a bit-by-bit basis and overcomes the complexity of using a sequence detector. The performance of this detector is shown to be superior to that of the conventional receiver.
Peng, M., Guo, Y.J. & Barton, S.K. 1996, 'One-shot linear decorrelating detector for asynchronous CDMA', Conference Record / IEEE Global Telecommunications Conference, pp. 1301-1305.
A one-shot linear decorrelating detector(LDD) for the detection of asynchronous CDMA is presented. By treating every user as two independent users and using maximal ratio combining, a bit-by-bit detection is obtained. By applying a phase estimation algorithm on the output of the one-shot LDD, it is shown that the proposed detector can be used for the detection of asynchronous CDMA without the knowledge of carrier phase of any user. Simulation results show that the performance of the proposed detector approaches that of the optimum detector for single user transmission.
Fuente, M.P., Guo, Y.J. & Barton, S.K. 1996, 'New scheme for direct sequence spread spectrum radio LANs', IEEE International Symposium on Spread Spectrum Techniques & Applications, pp. 1320-1324.
A new direct sequence spread spectrum scheme for ISM band Radio Local Area Networks using BPSK modulation and matched filter receivers is presented. It employs an optimized 22-chip sequence whose two 11-chip segments are alternately used as spreading sequences for adjacent symbols. Owing to the low cross-correlation between the two 11-chip segments, the inter-symbol interference caused by long delays in multipath channels is significantly reduced. In the paper, a receiver structure using the optimized sequence and time diversity is described and simulation results are given. Compared with the schemes using the short 11-chip Barker code and long M-sequences, the new scheme offers superior system performance.
Alkussayer, H.M., Guo, Y.J. & Barton, S.K. 1996, 'Low-cost multi-user receiver for synchronous CDMA systems', Conference Record / IEEE Global Telecommunications Conference, pp. 1588-1591.
The effect of noise enhancement of the linear decorrelating detector (LDD) is investigated by studying a low complexity receiver for synchronous Code Division Multiple Access (CDMA) systems. Using Gold codes as the spreading sequences a general formula of the decorrelating matrix is obtained, which leads to a simplified receiver structure and explicit expression of the bit error ratio (BER). It is shown that even with multiple access interference (MAI) reduced, the BER of the system is still dependent on the bandwidth efficiency. For a given bandwidth, efficiency, the system performance improves when the processing gain is increased.
Gillies, D.A.G., Johnson, I.R., Guo, Y.J., Barton, S.K. & Wilkinson, T.A. 1995, 'Synchronization techniques for radio LANs', IEE Colloquium (Digest).
The HIPERLAN system will operate in the 5 GHz and the 17 GHz bands at a data rate of > 23.5 Msymbols. Access to the radio medium is assumed to be asynchronous and the medium to be a Rayleigh fading channel. These would need a robust, synchronization mechanism, so that both timing instants in the receiver can be chosen and equalization performed to mitigate the effects of the time dispersive channel. Results show that the codes perform well under moderately severe channel conditions. An optimum 16 bit sequence was selected for appending to the start of frame synchronization sequence to make up for the full 48 bit training sequence. The added sequence preserves the desired correlation function properties of low sidelobes and zero imaginary part.
Guo, Y.J. & Barton, S.K. 1995, 'Flat printed lens and reflector antennas', IEE Conference Publication, pp. 253-256.
The performance of the printed single and double layer phase correcting arrays is theoretically investigated. The latest development of the single printed reflector is also reported. The effective design of a practical size single printed reflector for the reception of direct broadcasting by satellite is discussed, The reflector encompasses three full Fresnel zones and a quarter wave zone, with a 59.4 cm- diameter and 0.8 focal length to diameter ratio. A 43% optimum antenna efficiency and a bandwidth of greater than 10% are determined. The close-in sidelobes of the antenna are around -22dB and the far-out sidelobes are lower than -30dB.
Fuente, M.P., Guo, Y.J., Wilkinson, T.A. & Barton, S.K. 1995, 'Direct sequence spread spectrum radio LANs', IEE Colloquium (Digest).
The performance of direct sequence spread spectrum (DSSS) ISM band Radio Local Area Networks (RLANs) using BPSK modulation and matched filter receivers is investigated. Short and long pseudonoise (PN) spreading sequences, a Barker code and an M- sequence, have been employed in both differential and coherent systems operating in a Rayleigh fading multipath channel with different delay spreads. A channel estimator was designed to perform the system synchronization and control the receiver in order to mitigate the multipath fading and time-dispersion effects by using various multipath diversity techniques. It is found that with low delay spreads the short sequence leads to much better system performance than the long one. It is also shown that use of coherent instead of differential techniques increases the maximum tolerable delay spread.
GUO, Y.J. & BARTON, S.K. 1992, 'HIGH-EFFICIENCY ZONE-PLATE REFLECTOR INCORPORATING PRINTED RESONATORS', EIGHTH INTERNATIONAL CONFERENCE ON ANTENNAS AND PROPAGATION, PTS 1 AND 2, 8TH INTERNATIONAL CONF ON ANTENNAS AND PROPAGATION, INST ELECTRICAL ENGINEERS, HERIOT WATT UNIV, EDINBURGH, SCOTLAND, pp. 620-622.
Guo, Y.J. & Barton, S.K. 1992, 'Flat printed zone plate antennas for DBS reception', IEE Conference Publication, pp. 355-358.
A systematic investigation on flat printed phase correcting zone plate reflector antennas is presented. A multi-layered structure is proposed and a circular quarter-wave zone plate reflector with 54.8% efficiency is reported. When the zone plate reflector is offset, the circular zones become elliptical ones with their centers moved away successively from where the feed is pointed at. Experimental results on an offset half-wave zone plate reflector is given. Unfortunately, the antenna sidelobe level shown in the paper is much worse than that of the CCIR standard, which presently limits the zone plate reflectors as reception-only antennas. However, more recent experiments have shown that the sidelobes of the quarter-wave zone plate reflectors can be significantly improved by introducing better phase compensation and various approaches are being investigated.
Guo, Y.J., Barton, S.K. & Wright, T.M.B. 1991, 'Focal field distribution of Fresnel zone plate antennas', IEE Conference Publication, pp. 6-8.
With the arrival of high power direct broadcasting satellites, there is an increasing demand for low-cost, environmentally unobtrusive antennas. An interesting candidate in this respect is the improved Fresnel zone plate, on which research is being carried out at the University of Bradford in colaboration with Mawzones Ltd. In this paper, a theoretical study on the focal field distributions of the simple Fresnel zone plate (FZP) antenna and its phase-correcting versions is reported.
Guo, Y.J., Barton, S.K. & Wright, T.M.B. 1991, 'Design of high efficiency Fresnel zone plate antennas', AP-S International Symposium (Digest) (IEEE Antennas and Propagation Society), pp. 182-185.
With a family of ideal radiation patterns, the theory for designing high-efficiency phase-correcting FZP (Fresnel zone plate) antennas is presented. The optimum 3-dB beamwidth of the feed pattern as a function of F/D (focal length/diameter) of the plate, the relation between the phase efficiency of the antenna and the number of subzones used in each full-wave zone, and the total efficiency limits of various versions are given. It is found that the maximum efficiency of a practical FZP antenna is usually less than 70%. The theory has been employed in designing a four-layer experimental FZP reflector antenna, and good agreement between the theoretical expectation and the measured value is obtained.

Journal articles

Zhang, T., Pegrum, C., Du, J. & Guo, Y.J. 2017, 'Simulation and measurement of a Ka-band HTS MMIC Josephson junction mixer', Superconductor Science and Technology, vol. 30, no. 1.
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&copy; 2016 IOP Publishing Ltd. We report modeling and simulation results for a Ka band high-temperature superconducting (HTS) monolithic microwave integrated circuit (MMIC) Josephson junction mixer. A Verilog-A model of a Josephson junction is established and imported into the system simulator to realize a full HTS MMIC circuit simulation containing the HTS passive circuit models. Impedance matching optimization between the junction and passive devices is investigated. Junction DC I-V characteristics, current and local oscillator bias conditions and mixing performance are simulated and compared with the experimental results. Good agreement is obtained between the simulation and measurement results.
Yang, T., Yang, L., Guo, J. & Yuan, J. 2017, 'A Non-orthogonal Multiple-Access Scheme Using Reliable Physical-layer Network Coding and Cascade-Computation Decoding', IEEE Transactions on Wireless Communications, vol. 16, no. 3, pp. 1633-1645.
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This paper studies non-orthogonal transmission over a K-user fading multiple access channel. We propose a new reliable physical-layer network coding and cascade-computation decoding scheme. In the proposed scheme, K single-antenna users encode their messages by a same practical channel code and QAM modulation, and transmit simultaneously. The receiver chooses K linear coefficient vectors and computes the associated K layers of finite-field linear message-combinations in a cascade manner. Finally, the K users' messages are recovered by solving the K linear equations. The proposed can be regarded as a generalized onion peeling. We study the optimal network coding coefficient vectors used in the cascade-computation. Numerical results show that the performance of the proposed approaches that of the iterative maximum a posteriori probability detection and decoding scheme, but without using receiver iteration. This results in considerable complexity reduction, processing delay and easier implementation. Our proposed scheme significantly outperforms the iterative detection and decoding scheme with a single iteration, for example, by 1.7 dB for the two user case. The proposed scheme provides a competitive solution for non-orthogonal multiple access.
Du, J., Weily, A.R., Gao, X., Zhang, T., Foley, C.P. & Guo, Y.J. 2017, 'HTS step-edge Josephson junction terahertz harmonic mixer', Superconductor Science and Technology, vol. 30, no. 2.
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&copy; 2016 Federal Australian Crown copyright. A high-temperature superconducting (HTS) terahertz (THz) frequency down-converter or mixer based on a thin-film ring-slot antenna coupled YBa 2 Cu 3 O 7-x (YBCO)/MgO step-edge Josephson junction is reported. The frequency down-conversion was achieved using higher order harmonics of an applied lower frequency (19-40 GHz) local oscillator signal in the Josephson junction mixing with a THz signal of over 600 GHz, producing a 1-3 GHz intermediate frequency signal. Up to 31st order of harmonic mixing was obtained and the mixer operated stably at temperatures up to 77 K. The design details of the antenna, HTS Josephson junction mixer, the matching and isolation circuits, and the DC and RF performance evaluation are described in this paper.
Du, J., Pegrum, C.M., Gao, X., Weily, A.R., Zhang, T., Guo, Y.J. & Foley, C.P. 2017, 'Harmonic Mixing Using a HTS Step-Edge Josephson Junction at 0.6 THz Frequency', IEEE Transactions on Applied Superconductivity, vol. 27, no. 4.
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&copy; 2002-2011 IEEE. A high-temperature superconducting (HTS) terahertz (THz) heterodyne mixer based on a thin-film antenna-coupled YBa 2 Cu 3 O 7- x step-edge Josephson junction is presented. The frequency down-conversion from 0.6 THz to an intermediate frequency (IF) of 2 GHz was achieved using high-order harmonic mixing of a local oscillator (LO), thus removing the need to use a second THz source as the LO pumping source. The DC and RF characteristics of the harmonic mixer as well as the relationship of the IF output power versus the harmonic number were experimentally studied and compared with simulated results. Most of our measurements were made at 40 K, but we also observed stable harmonic mixing at 77 K which we believe has not been reported previously in HTS junction mixers.
Chen, X., Qin, P.Y., Guo, Y.J. & Fu, G. 2017, 'Low-profile and wide-beamwidth dual-polarized distributed microstrip antenna', IEEE Access, vol. 5, pp. 2272-2280.
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&copy; 2013 IEEE. A low-profile and wide-beamwidth dual-polarized distributed microstrip antenna is presented in this paper. Four isolated micro patches are proposed as the radiation components and are excited by a compact differential-fed network. The micro patches in two diagonals determine the operating frequency bands of the two polarizations, respectively. By increasing the distances between the micro patches, the beamwidth in E plane can be broadened. Shorting poles between the patches and the ground plane are used to achieve good impedance matching. Compact dual-polarized differential-fed networks are also studied and compared with achieve the best antenna performance. To validate the proposed method, a wide-beamwith dual-polarized distributed microstrip antenna, whose dual polarizations operate at 2 and 2.2 GHz, respectively, is manufactured and measured. The external dimensions of the antenna is 70mm 10 mm (0.49 0.07 ). The experimental results agree well with the simulated ones. The 3dB beamwidths in E planes reach 116&deg; and 115&deg;, and the gains are 5.15 and 5.5 dB for two polarizations, respectively. Meanwhile, the cross polarizations are less than -26.2 and -27.8 dB. In addition, the impedance bandwidths of 9.2% and 9.9% for VSWR leq 2 are achieved, and the port isolation is greater than 25.4 dB in the bands.
Huang, J., Qiu, F., Lin, W., Tang, Z., Lei, D., Yao, M., Chu, Q. & Guo, Y.J. 2017, 'A New Compact and High Gain Circularly-Polarized Slot Antenna Array for Ku Band Mobile Satellite TV Reception', IEEE Access, vol. 5, pp. 6707-6714.
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Jia, Y., Liu, Y., Guo, Y.J., Li, K. & Gong, S. 2017, 'A dual-patch polarization rotation reflective surface and its application to ultra-wideband RCS reduction', IEEE Transactions on Antennas and Propagation, vol. 65, no. 6, pp. 3291-3295.
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&copy; 2017 IEEE. An ultra-wideband polarization rotation reflective surface (PRRS) with a high polarization conversion ratio (PCR) is proposed, which can reflect a linearly polarized incident wave with 90&deg; polarization rotation. The unit cell of the proposed PRRS consists of a square and L-shaped patches printed on a substrate, which is covered by a superstrate and backed by a metallic ground. The two patches are connected to the ground using two metallic vias, respectively. Compared with the previously reported PRRS, the polarization rotation bandwidth of the proposed PRRS is enhanced from 49% to 97% with a high PCR of 96%. The frequency responses within the operation frequency band are consistent under oblique incident waves. Furthermore, the designed PRRS is applied to the ultra-wideband radar cross-section (RCS) reduction by forming a checkerboard surface. A 10-dB RCS reduction is achieved over an ultrawideband of 98%. To validate the simulation results, a prototype of the checkerboard surface is fabricated and measured. A good agreement between the experimental and simulation results is obtained.
Sutton, G.J., Liu, R. & Guo, Y.J. 2017, 'Harmonising Coexistence of Machine Type Communications with Wi-Fi Data Traffic under Frame-based LBT', IEEE Transactions on Communications, pp. 1-1.
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Qin, C., Ni, W., Tian, H., Liu, R.P. & Guo, Y.J. 2017, 'Joint Beamforming and User Selection in Multiuser Collaborative MIMO SWIPT Systems with Non-negligible Circuit Energy Consumption', IEEE Transactions on Vehicular Technology, pp. 1-1.
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Chen, S.-.L., Wei, F., Qin, P.-.Y., Guo, Y.J. & Chen, X. 2017, 'A Multi-linear Polarization Reconfigurable Unidirectional Patch Antenna', IEEE Transactions on Antennas and Propagation, pp. 1-1.
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Li, K., Liu, Y., Jia, Y. & Guo, Y.J. 2017, 'A High Gain and Wideband Low RCS Circularly Polarized Antenna Using Chessboard Polarization Conversion Metasurfaces', IEEE Transactions on Antennas and Propagation, pp. 1-1.
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Huang, X. & Guo, Y.J. 2017, 'Radio Frequency Self-Interference Cancellation With Analog Least Mean-Square Loop', IEEE Transactions on Microwave Theory and Techniques, pp. 1-15.
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Karmokar, D., Guo, Y., Qin, P.-.Y., Esselle, K. & Bird, T. 2017, 'Forward and Backward Beam Scanning Tri-Band Leaky-Wave Antenna', IEEE Antennas and Wireless Propagation Letters, pp. 1-1.
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Zhu, H.L., Chung, K.L., Ding, C., Wei, G., Zhang, C. & Guo, Y.J. 2017, 'Polarization-Rotated Waveguide Antennas for Base-Station Applications', IEEE Antennas and Wireless Propagation Letters, vol. 16, pp. 1545-1548.
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Zhang, T., Gao, X., Wang, W., Du, J., Pegrum, C. & Guo, Y.J. 2017, 'A 36 GHz HTS MMIC Josephson Mixer—Simulation and Measurement', IEEE Transactions on Applied Superconductivity, vol. 27, no. 4, pp. 1-5.
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Wei, F., Qin, P.-.Y., Guo, Y.J. & Shi, X.-.W. 2016, 'Design of multi-band bandpass filters based on stub loaded stepped-impedance resonator with defected microstrip structure', IET Microwaves, Antennas & Propagation, vol. 10, no. 2, pp. 230-236.
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The design of multi-band bandpass filters (BPFs) employing stub loaded stepped-impedance resonator with defected microstrip structure (SL-SIR-DMS) is presented in this study for the first time. The proposed SL-SIR-DMS is created by embedding DMS on the low-impedance line of the SL-SIR. It is found that different defected structures can lead to different frequency responses. In addition, by using DMS, tri-band and even quad-band responses can be easily achieved without increasing the resonator size. As verification, one tri-band SL-SIR-DMS and one quad-band SL-SIRDMS are designed and analysed using even/odd-mode method. Subsequently, one tri-band BPF and one quad-band BPF have been developed with pseudo-interdigital coupling to realise good out-of-band performance. The predicted results are compared with measured ones and good agreement is achieved. Compared with BPFs using only SL-SIR, the proposed filters with DMS are more compact due to the slow-wave characteristic. Compared with the BPFs using defected ground structure to improve the stopband performance, the proposed ones can realise comparable wide stopbands but maintaining the signal integrity on the ground plane for packaging purpose.
Qin, P.-.Y., Guo, Y.J. & Weily, A.R. 2016, 'Broadband Reflectarray Antenna Using Subwavelength Elements Based on Double Square Meander-Line Rings', IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION, vol. 64, no. 1, pp. 378-383.
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Guan, D.F., Ding, C., Qian, Z.P., Zhang, Y.S., Jay Guo, Y. & Gong, K. 2016, 'Broadband High-Gain SIW Cavity-Backed Circular-Polarized Array Antenna', IEEE Transactions on Antennas and Propagation, vol. 64, no. 4, pp. 1493-1497.
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&copy; 2016 IEEE. A circularly polarized (CP) 4 4 array antenna based on substrate integrated waveguide (SIW) technology is presented. Circular polarization is achieved by applying the sequential rotation technique (SRT) with a well-designed sequential feed network and linear-polarized array elements. The proposed 4 4 array has a wide axial ratio (AR) bandwidth of 14% from 18.3 to 21.1 GHz with gain > 13 dBic. Then, the array is expanded to achieve higher gains. A 16 16-element array is designed, fabricated, and tested. Test results show that the 16 16 array has an AR bandwidth of 13.8% from 18.5 to 21.25 GHz and a peak gain of 25.9 dBic at 20.5 GHz.
Guzmán-Quirós, R., Weily, A.R., Gómez-Tornero, J.L. & Guo, Y.J. 2016, 'A Fabry-Pérot Antenna with Two-Dimensional Electronic Beam Scanning', IEEE Transactions on Antennas and Propagation, vol. 64, no. 4, pp. 1536-1541.
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&copy; 2016 IEEE. A novel fixed-frequency electronically steerable Fabry-P&eacute;rot Antenna (FPA) with electronic two-dimensional (2-D) (azimuth and elevation) steering capability is presented. The configuration is based on a centrally fed Fabry-P&eacute;rot cavity (FPC) loaded with a tunable high impedance surface (HIS). Varactor diodes are used to electronically tune the HIS reflection coefficient, forming four azimuthal sectors that are independently controlled by four control signals, respectively. It is demonstrated that this simple configuration generates a pencil beam that can be pointed to eight discrete azimuthal directions, whereas continuous elevation scanning is also attained simultaneously for each azimuthal direction by controlling the leaky-wave propagation constant. The theory, simulation analysis, and experimental results obtained from a prototype operating at 5.5 GHz are presented to validate the antenna design.
Wei, F., Qin, P.Y., Guo, Y.J., Ding, C. & Shi, X.W. 2016, 'Compact Balanced Dual-and Tri-Band BPFs Based on Coupled Complementary Split-Ring Resonators (C-CSRR)', IEEE Microwave and Wireless Components Letters, vol. 26, no. 2, pp. 107-109.
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&copy; 2016 IEEE. Two multi-band balanced bandpass filters (BPFs) are proposed by embedding multi-band coupled complementary split-ring resonators (C-CSRRs) into a balanced stepped-impedance microstrip-slotline transition structure. The proposed C-CSRR is made from two or three nested CSRRs with a pair of coupling slotlines in the open end of each ring, which can result in dual-band or tri-band bandpass responses, respectivley. It is found that a high and wideband common-mode (CM) suppression can be achieved for the proposed filters. Moreover, the center frequencies of the differential-mode (DM) passbands are independent from the CM responses, which significantly simplify the design procedure. In order to validate its practicalbility, two balanced BPFs with two and three DM passbands are fabricated and good agreement between simulated and measured results is observed.
Liu, Y., Li, K., Jia, Y., Hao, Y., Gong, S. & Guo, Y.J. 2016, 'Wideband RCS reduction of a slot array antenna using polarization conversion meta surfaces', IEEE Transactions on Antennas and Propagation, vol. 64, no. 1, pp. 326-331.
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&copy; 2015 IEEE. A new approach to reducing the monostatic radar cross section (RCS) and preserving the radiation characteristics of a slot array antenna by employing polarization conversion metasurfaces (PCMs) is presented in this communication. The PCM is arranged in a chessboard configuration consisting of fishbone-shaped element. It is placed on the surface of the slot array antenna. The characteristics and mechanism of the RCS reduction are analyzed. Simulated and experimental results show that the monostatic RCS reduction band of the antenna with PCM ranges between 6.0 and 18.0 GHz for normally impinging both x-and y-polarized waves. The radiation characteristics of the antenna are well preserved simultaneously in terms of the impedance bandwidth, radiation patterns, and realized boresight gains.
Jia, Y., Liu, Y., Guo, Y.J., Li, K. & Gong, S.X. 2016, 'Broadband polarization rotation reflective surfaces and their applications to RCS reduction', IEEE Transactions on Antennas and Propagation, vol. 64, no. 1, pp. 179-188.
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&copy; 2015 IEEE. A novel broadband polarization rotation (PR) reflective surface (PRRS) with a high polarization conversion ratio (PCR) is proposed, which can reflect the linearly polarized incident wave with 90&deg; PR. The proposed PRRS consists of a periodic array of square patches printed on a substrate, which is backed by a metallic ground. By connecting the square patch with the ground using two nonsymmetric vias, a 49% PR bandwidth is achieved with a high PCR of 96%, which is a significant improvement from the state-of-the-art 29% PR bandwidth. Moreover, the frequency responses within the operation frequency band are consistent under oblique incident waves. Furthermore, another ultra-wideband PRRS with a periodic array of quasi-L-shaped patches is proposed, which increases the PR bandwidth further to 103%. In addition, the designed PRRS is applied to wideband radar cross section (RCS) reduction. Different arrangements of the unit cells of the PRRS are proposed and their effects on RCS reduction are investigated. To validate the simulation results, prototypes of the PRRSs are fabricated and measured. The measured results are in good agreement with the simulated ones.
Pegrum, C., Zhang, T., Du, J. & Guo, Y.J. 2016, 'Simulation of HTS Josephson Mixers', IEEE Transactions on Applied Superconductivity, vol. 26, no. 3.
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&copy; 2016 IEEE. The Commonwealth Scientific and Industrial Research Organization has developed superconducting microwave monolithic integrated circuit (MMIC) mixers using step-edge Josephson junctions and on-chip filters, made from YBaCuO on MgO substrates. Integration into an MMIC results in a compact and efficiently coupled structure. These have been shown to have outstanding conversion efficiency, dynamic range, and linearity. We report here a range of simulations of this type of mixer. We have mainly used Josephson simulators and analyze the data in both the time and frequency domains. More recently, we have also used microwave simulators incorporating a novel Verilog-A Josephson junction model that we have developed. We have looked at the interactions of junction bias current, local oscillator power, and radio-frequency input power with conversion efficiency, dynamic range, and linearity. Good agreement is found overall with measurements.
Li, Z., Zhao, G., Li, S., Sun, H., Tao, R., Huang, X. & Guo, Y.J. 2016, 'Rotation Feature Extraction for Moving Targets Based on Temporal Differencing and Image Edge Detection', IEEE Geoscience and Remote Sensing Letters, vol. 13, no. 10, pp. 1512-1516.
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&copy; 2016 IEEE. A rotation parameter extraction method based on temporal differencing and image edge detection from range-Doppler images is presented in this letter. The proposed method first detects the motion trail of the moving pixels caused by the rotating parts in temporal differential range-Doppler images using image edge detection. A Doppler-slow-time image is then generated from the edge pixels on the motion trail. Finally, the rotation parameters are extracted from the Doppler-slow-time image. The proposed method is simple, rapid, and practical. Computer simulations and experimental results demonstrate its effectiveness in terms of computation time compared with existing methods.
Ji, L.Y., Qin, P.Y., Guo, Y.J., Ding, C., Fu, G. & Gong, S.X. 2016, 'A Wideband Polarization Reconfigurable Antenna with Partially Reflective Surface', IEEE Transactions on Antennas and Propagation, vol. 64, no. 10, pp. 4534-4538.
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&copy; 2016 IEEE. A novel partially reflective surface (PRS) antenna is proposed, which can electronically alter its polarization between linear polarization, left-hand circular polarization (CP), and right-hand CP. The antenna consists of a shorted annular patch antenna as the source, a PRS structure to enhance the gain, and a reconfigurable Wilkinson power divider as the feed network. Four p-i-n diodes are inserted into each branch of the power divider to change its electrical length. By switching the p-i-n diodes ON and OFF, a phase difference of 0&deg;, 90&deg;, or -90&deg; can be realized at the two output ports of the feed network, hence enabling the antenna to radiate either a linearly polarized signal or left/right-handed circularly polarized signal. A prototype antenna with the biasing network is designed, fabricated, and measured. Good agreement between the simulated and measured results is achieved. Measurement results show that the proposed antenna has an overlapped 10-dB impedance bandwidth and 3-dB axial-ratio bandwidth of 4.7-5.36 GHz (13.1%). The average realized gains are 9 dBi/dBic, which remain reasonably stable for different polarizations. The proposed antenna outperforms most of the reported polarization reconfigurable antennas for its wide bandwidth and relatively high gain.
Du, J., Wang, J., Zhang, T., Bai, D., Guo, Y.J. & He, Y. 2015, 'Demonstration of a portable HTS MMIC microwave receiver front-end', IEEE Transactions on Applied Superconductivity, vol. 25, no. 3.
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&copy; 2014 IEEE. We report the first demonstration of a portable HTS monolithic microwave integrated circuit (MMIC) receiver front-end module operating on a commercial mini cryocooler. The HTS circuit consists of a step-edge junction mixer and a number of HTS filters fabricated on a single MgO substrate. The HTS MMIC circuit is integrated with the mini cryocooler. The sample vacuum chamber, cold-head, compressor and cooling fans are all packed into one customer-designed portable box of approximately 350 mm 350 mm 250 mm in dimension. The HTS Josephson junction-based microwave circuit operated successfully in the cryocooler unshielded without observable performance degradation. The design and implementation of the compact unit and performance evaluation of a HTS MMIC frequency down-converter are presented.
Wei, F., Guo, Y.J., Qin, P.-.Y. & Shi, X.W. 2015, 'Compact Balanced Dual-and Tri-band Bandpass Filters Based on Stub Loaded Resonators', Microwave and Wireless Components Letters, IEEE, vol. 25, pp. 76-78.
Zhang, J., Huang, X., Dyadyuk, V., Guo, Y.J. & others 2015, 'Massive hybrid antenna array for millimeter-wave cellular communications', Wireless Communications, IEEE, vol. 22, pp. 79-87.
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Gao, S., Chamberlain, N.F. & Guo, Y.J. 2015, 'Guest Editorial Antennas for Satellite Communications', IEEE Transactions on Antennas and Propagation, vol. 63, no. 4, pp. 1186-1190.
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&copy; 1963-2012 IEEE. The objective of this special issue is to bring together the most updated research contributions addressing antennas for satellite communications (both spaceborne and user terminals), and propose new applications, solutions, and challenges for the future.
Zhang, T., Du, J., Wang, J., Bai, D., Guo, Y.J. & He, Y. 2015, '30 GHz HTS receiver front-end based on monolithic Josephson mixer', IEEE Transactions on Applied Superconductivity, vol. 25, no. 3.
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&copy; 2014 IEEE. A compact, high-gain, and low-noise Ka band HTS Josephson junction-based receiver front-end module for wireless communication is presented in this paper. The front-end module consists of biasing circuits, a semiconductor low-noise amplifier, and a monolithic HTS circuit consisting of an Josephson mixer, bandpass and lowpass filters. The semiconductor LNA in the first stage is applied to achieve a low noise figure of the whole front-end module. Integration of the Josephson mixer with a number of HTS passive components on a single chip improves the coupling efficiency and reduces the connection losses between the components. The total dimension of the packaged front-end module is below 25 mm 20 mm 15 mm, which is very compact. Measurement result shows that the front-end module has an overall conversion gain around 40 dB, and a low noise figure close to 0 dB with an LO driving power around -38 dBm at 40 K.
Ji, L.-.Y., Guo, Y.J., Qin, P.-.Y., Gong, S.-.X. & Mittra, R. 2015, 'A Reconfigurable Partially Reflective Surface (PRS) Antenna for Beam Steering', IEEE Transactions on Antennas and Propagation, vol. 63, no. 6, pp. 2387-2395.
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The design of a novel partially reflective surface (PRS) antenna with the capability of beam steering is presented in this paper. The beam steering is realized by employing a reconfigurable PRS structure to achieve a changeable reflection phase as well as using a phased array as the source to excite the PRS antenna. A prototype antenna including the biasing network is fabricated and measured. It achieves a consistent beam steering from -15 degrees to 15 degrees with respect to the broadside direction across an overlapped frequency range from 5.5 to 5.7 GHz with measured realized gains over 12 dBi. Good agreement between the simulated and measured results for the input reflection coefficients and radiation patterns is achieved, which validates the feasibility of the design principle. Compared with other beam steering PRS antennas, the proposed one enables a larger beam steering angle with comparable gains, requires a simpler biasing network, and is more compact.
Ding, C., Guo, Y.J., Qin, P. & Yang, Y. 2015, 'A Compact Phase Shifter Employing Reconfigurable Defected Microstrip Structure (RDMS) for Phased Array Antennas'.
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Qin, P.-.Y., Wei, F. & Guo, Y. 2015, 'A Wideband-to-Narrowband Tunable Antenna Using A Reconfigurable Filter', IEEE Transactions on Antennas and Propagation, vol. 63, no. 5, pp. 2282-2285.
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A novel microstrip circular disc monopole antenna with a reconfigurable 10-dB impedance bandwidth is proposed in this communication for cognitive radios (CRs). The antenna is fed by a microstrip line integrated with a bandpass filter based on a three-line coupled resonator (TLCR). The reconfiguration of the filter enables the monopole antenna to operate at either a wideband state or a narrowband state by using a PIN diode. For the narrowband state, two varactor diodes are employed to change the antenna operating frequency from 3.9 to 4.82 GHz continuously, which is different from previous work using PIN diodes to realize a discrete tuning. Similar radiation patterns with low cross-polarization levels are achieved for the two operating states. Measured results on tuning range, radiation patterns, and realized gains are provided, which show good agreement with numerical simulations.
Xu, L., Huang, D. & Guo, Y.J. 2015, 'Robust Blind Learning Algorithm for Nonlinear Equalization Using Input Decision Information', IEEE Transactions on Neural Networks and Learning Systems, vol. 26, no. 12, pp. 3009-3020.
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In this paper, we propose a new blind learning algorithm, namely, the Benveniste--Goursat input--output decision (BG-IOD), to enhance the convergence performance of neural network-based equalizers for nonlinear channel equalization. In contrast to conventional blind learning algorithms, where only the output of the equalizer is employed for updating system parameters, the BG-IOD exploits a new type of extra information, the input decision information obtained from the input of the equalizer, to mitigate the influence of the nonlinear equalizer structure on parameters learning, thereby leading to improved convergence performance. We prove that, with the input decision information, a desirable convergence capability that the output symbol error rate (SER) is always less than the input SER if the input SER is below a threshold, can be achieved. Then, the BG soft-switching technique is employed to combine the merits of both input and output decision information, where the former is used to guarantee SER convergence and the latter is to improve SER performance. Simulation results show that the proposed algorithm outperforms conventional blind learning algorithms, such as stochastic quadratic distance and dual mode constant modulus algorithm, in terms of both convergence performance and SER performance, for nonlinear equalization.
Ye, S., Geng, J., Liang, X., Jay Guo, Y. & Jin, R. 2015, 'A Compact Dual-Band Orthogonal Circularly Polarized Antenna Array with Disparate Elements', IEEE Transactions on Antennas and Propagation, vol. 63, no. 4, pp. 1359-1364.
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&copy; 1963-2012 IEEE. A dual-band orthogonally and circularly polarized antenna array with disparate elements is presented. By using corner-truncated stacked patches as elements, both left hand circular polarization (LHCP) in 12 GHz band and right hand circular polarization (RHCP) in 14 GHz band are realized in a shared antenna aperture. Furthermore, by employing disparate elements, the coupling between the two bands is suppressed effectively inside the feed network, hence improving isolation. The measured results of a four-element array agreed well with the simulated ones, achieving isolation better than 20 dB in the dual bands, and a maximum gain of 13.2 dBic for the LHCP and 13.9 dBic for the RHCP. The proposed array can find applications in satellite communications.
Huang, X., Zhang, J.A. & Guo, Y.J. 2015, 'Out-of-band emission reduction and a unified framework for precoded OFDM', IEEE Communications Magazine, vol. 53, no. 6, pp. 151-159.
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&copy; 1979-2012 IEEE. OFDM has been regarded as a promising candidate for use in cognitive radio systems with dynamic spectrum reuse capability. However, conventional OFDM has significant OOBE, which can cause severe interference to systems operating in adjacent frequency bands. In addition to conventional techniques such as spectral shaping filtering, guard band insertion, and time domain windowing, new OOBE reduction techniques, including cancellation carrier and spectral precoding, have been proposed in recent years. This article reviews various OOBE reduction techniques and proposes a generalized lowcomplexity OOBE reduction framework for discrete Fourier transform precoded OFDM. With the allocation of explicit frequency domain cancellation subcarriers and data domain cancellation symbols, the proposed framework enables various configurations to achieve significant OOBE reduction with low implementation complexity, and provides flexibility in balancing OOBE reduction and other performance metrics such as peak-to-average power ratio.
Wei, F., Guo, Y.J., Qin, P.-.Y. & Shi, X.W. 2014, 'Wideband bandpass filter with a broad stopband based on a triple-mode stub-loaded resonator', Microwave and Optical Technology Letters, vol. 56, no. 12, pp. 2878-2881.
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Cheng, P., Chen, Z., Rui, Y., Guo, Y.J. & Guizani, M. 2014, 'Limited feedback unitary precoding for MIMO full stream transmission', IEEE Transactions on Vehicular Technology, vol. 63, no. 8, pp. 4092-4096.
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&copy; 2014 IEEE. Limited feedback precoding (LFP) significantly improves multiple-input-multiple-output (MIMO) spatial multiplexing link reliability with a small amount of feedback from the receiver back to the transmitter. One of the key problems with LFP is how to select an optimal precoder from a predetermined unitary codebook. We find that the conventional precoder selection criteria are not applicable to the full stream transmission mode with linear [zero forcing (ZF) and minimum mean square error (MMSE)] receivers. To solve this issue, a novel singular value decomposition (SVD)-based precoder selection criterion optimizing the bit error rate (BER) performance is proposed in this paper. The proposed criterion features a unified structure for both linear receivers and it can be calculated based on fast matrix computation algorithms. Its effectiveness in the full stream transmission mode is verified by simulation results.
Sun, Z., Esselle, K.P., Zhong, S.S. & Guo, Y.J. 2014, 'Shared-aperture dual-band dual-polarization array using sandwiched stacked patch', Progress In Electromagnetics Research C, vol. 52, pp. 183-195.
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An L/C dual-band dual-polarized (DBDP) shared aperture microstrip array is proposed in the paper. In the array, the sandwiched stacked patch is employed for the L-band element to exploit the bandwidth for given element thickness. Several key issues regarding the proposed structure are discussed, including: 1) benefit of proposed L band sandwiched stacked patch; 2) C-band feeding method; 3) radiation performance in both bands. A prototype array of L/C DBDP sandwiched stacked patch is designed and fabricated to verify the feasibility of the proposed structure, where the measured data are presented in the paper. &copy; 2010 EMW Publishing. All Rights Reserved.
Chan, K.Y., Ramer, R., Mansour, R.R. & Guo, Y.J. 2014, '60 GHz to E-band switchable bandpass filter', IEEE Microwave and Wireless Components Letters, vol. 24, no. 8, pp. 545-547.
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A novel reconfigurable millimeter-wave bandpass filter (BPF) capable of operating between 60 GHz and the E-band, with a good channel isolation, is presented. This fully integrated filter is designed with all reconfigurable elements embedded for compactness. A new method that increases fractional bandwidths is introduced. It uses inductively coupled invertersbut does not require tuning. New circuit models are provided for these inverters, reconfigurable resonators, and the reconfigurable bandstop stubs. The compact BPF achieved a footprint of only 4.75 mm 3.75 mm. Measurements for the filters show good agreement with the simulation results. &copy; 2014 IEEE.
Ding, C., Guo, Y.J., Qin, P.-.Y., Bird, T.S. & Yang, Y. 2014, 'A Defected microstrip structure (DMS)-based phase shifter and its application to beamforming antennas', Antennas and Propagation, IEEE Transactions on, vol. 62, pp. 641-651.
Du, J., Bai, D.D., Zhang, T., Jay Guo, Y., He, Y.S. & Pegrum, C.M. 2014, 'Optimised conversion efficiency of a HTS MMIC Josephson down-converter', Superconductor Science and Technology, vol. 27, no. 10.
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&copy; 2014 IOP Publishing Ltd. A high-Tc superconducting (HTS) monolithic microwave integrated circuit (MMIC) Josephson down-converter that approaches zero conversion loss is reported. The all-HTS YBa2Cu3O7-x thin-film circuit consists of a step-edge Josephson junction mixer, a 10-12 GHz bandpass filter for the RF input, a lowpass filter for the IF output and a resonant strip line for local oscillator isolation; all are integrated on a single 10 mm 20 mm MgO substrate. The DC characteristics of the junction and its mixing properties have been experimentally studied and compared to the results of (a) a single Josephson mixer without the on-chip HTS filters, and (b) our previously reported MMIC down-converter which had very different junction characteristics. The Josephson junction parameters are analysed to give insight into their effect on the mixer performance.
Wei, F., Jay Guo, Y. & Shi, X.W. 2014, 'Compact balanced UWB bandpass filter with one narrow notched band', Microwave and Optical Technology Letters, vol. 56, no. 7, pp. 1626-1629.
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A compact balanced ultra-wideband bandpass filter (BPF) with one sharply notched band is presented in this article. The proposed BPF based on microstrip-to-slotline transition obtains favorable uniform differential-mode response and good common-mode suppression. Moreover, one narrow notched band with a 3 dB bandwidth of 6.8% is realized by introducing one coupled half-wavelength resonator. The fabricated filter has a more than 25% size reduction compared to the designs reported in open literature. The predicted results are compared with measured ones and good agreement is achieved. Copyright &copy; 2014 Wiley Periodicals, Inc.
Yang, X., Tao, X., Dutkiewicz, E., Huang, X., Guo, Y.J. & Cui, Q. 2013, 'Energy-efficient distributed data storage for wireless sensor networks based on compressed sensing and network coding', IEEE Transactions on Wireless Communications, vol. 12, no. 10, pp. 5087-5099.
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Recently, distributed data storage (DDS) for Wireless Sensor Networks (WSNs) has attracted great attention, especially in catastrophic scenarios. Since power consumption is one of the most critical factors that affect the lifetime of WSNs, the energy efficiency of DDS in WSNs is investigated in this paper. Based on Compressed Sensing (CS) and network coding theories, we propose a Compressed Network Coding based Distributed data Storage (CNCDS) scheme by exploiting the correlation of sensor readings. The CNCDS scheme achieves high energy efficiency by reducing the total number of transmissions N ttot and receptions N rtot during the data dissemination process. Theoretical analysis proves that the CNCDS scheme guarantees good CS recovery performance. In order to theoretically verify the efficiency of the CNCDS scheme, the expressions for N ttot and N rtot are derived based on random geometric graphs (RGG) theory. Furthermore, based on the derived expressions, an adaptive CNCDS scheme is proposed to further reduce N ttot and N rtot . Simulation results validate that, compared with the conventional ICStorage scheme, the proposed CNCDS scheme reduces N ttot , N rtot , and the CS recovery mean squared error (MSE) by up to 55%, 74%, and 76% respectively. In addition, compared with the CNCDS scheme, the adaptive CNCDS scheme further reduces N ttot and N rtot by up to 63% and 32% respectively. &copy; 2002-2012 IEEE.
Ye, S., Liang, X., Wang, W., Geng, J., Jin, R., Guo, Y.J. & Bird, T.S. 2013, 'Design of arbitrarily shaped planar microstrip antenna arrays with improved efficiency', International Journal of Antennas and Propagation, vol. 2013.
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A design technique is described for an arbitrarily shaped planar microstrip antenna array with improved radiation efficiency. In order to fully utilize the limited antenna aperture, several basic modules are proposed from which we construct the array. A consideration of the aperture shape shows that with several practical examples a proper combination of these basic modules not only allows the convenient design of arbitrarily-shaped microstrip array, but also helps to improve the aperture radiation efficiency. To confirm the feasibility of the approach, a circular array with 256 elements was constructed and fabricated. Both computed and measured aperture radiation results are compared and these demonstrate that the design technique is effective for arbitrarily-shaped planar microstrip arrays. &copy; 2013 Sheng Ye et al.
Cheng, P., Chen, Z., Rui, Y., Guo, Y.J., Gui, L., Tao, M. & Zhang, Q.T. 2013, 'Channel estimation for OFDM systems over doubly selective channels: A distributed compressive sensing based approach', IEEE Transactions on Communications, vol. 61, no. 10, pp. 4173-4185.
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Channel estimation for an orthogonal frequency-division multiplexing (OFDM) broadband system over a doubly selective channel is very challenging. This is mainly due to the significant Doppler shift, which results in a time-frequency doubly-selective (DS) channel. The DS channel features a large number of channel coefficients, which introduces inter-carrier interference (ICI) and forces the need for allocating a large number of pilot subcarriers. To tackle this problem, in this paper we propose a novel channel estimation scheme based on distributed compressive sensing (DCS) theory. Taking advantage of the basis expansion model (BEM) and the channel sparsity in the delay domain, we transform the original DS channel into a novel two-dimensional channel model, where several jointly sparse BEM coefficient vectors become the estimation goal. Then a special decoupling form originating from a novel sparse pilot pattern is designed for such estimation, which results in an ICI-free structure and enables the DCS application to make joint estimation of these vectors accurately. Combined with a smoothing treatment process, the proposed scheme can achieve significantly higher estimation accuracy than the existing ones, although with a much smaller number of pilot subcarriers. Theoretical analysis and simulation results both confirm its performance merits. &copy; 2013 IEEE.
Qin, P.-.Y., Guo, Y.J. & Ding, C. 2013, 'A beam switching quasi-Yagi dipole antenna', Antennas and Propagation, IEEE Transactions on, vol. 61, pp. 4891-4899.
Zhang, T., Du, J., Guo, Y.J. & Sun, X. 2013, 'A compact HTS bandpass microstrip filter with novel coupling structure for on-chip integration', Physica C: Superconductivity and its Applications, vol. 495, pp. 69-73.
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A compact low-complexity high-selectivity high-temperature superconducting (HTS) microstrip bandpass filter is presented in this paper, which consists of only three half-wavelength resonators. A novel coupling scheme is used to provide a pair of transmission zeros outside the passband, so that the selectivity of the filter is improved. The filter is fabricated on an MgO substrate with YBa 2 Cu 3 O 7-x (YBCO) coating. Measurement result shows an in-band insertion loss at 0.5 dB, a sharp slope, and a stopband rejection better than 20 dB. The compactness and high-selectivity features make the filter suitable for on-chip integration of HTS receiver front-ends. &copy; 2013 Published by Elsevier B.V. All rights reserved.
Zhang, T., Du, J., Guo, Y.J. & Sun, X. 2013, 'A 7-8.5 GHz high performance MMIC HTS josephson mixer', IEEE Microwave and Wireless Components Letters, vol. 23, no. 8, pp. 427-429.
A low-loss, low power consumption monolithic high-temperature superconducting (HTS) Josephson junction mixer at 7-8.5 GHz is presented. The mixer consists of a HTS YBa 2Cu 3O 7-x (YBCO) bandpass filter for RF input, a lowpass filter for IF output and a LO resonator integrated with a single Josephson junction. All the passive and active devices are fabricated on a 20 mmtimes 10 mm MgO substrate. Measurement result shows a conversion gain of -7 dB at 40 K, and -4.7 dB at 20 K. The IF output versus the RF input exhibits a wide linear range of conversion gains. The mixer has an extremely low LO power requirement at -32 dBm and a 50 nW power consumption. &copy; 2001-2012 IEEE.
Du, J., Zhang, T., Guo, Y.J. & Sun, X.W. 2013, 'A high-temperature superconducting monolithic microwave integrated Josephson down-converter with high conversion efficiency', Applied Physics Letters, vol. 102, no. 21.
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A compact high-T c superconducting monolithic microwave integrated circuit Josephson down-converter is presented. The circuit consists of a single Josephson junction mixer, a bandpass filter, a lowpass filter, and a resonator for local oscillator fabricated on a single 10 mm 20 mm chip of YBa 2 Cu 3 O 7-x film on MgO substrate. The down-converter demonstrates superior performance in terms of conversion efficiency, dynamic range, linearity, and low local oscillator power with stable operation from 20 to 77 K. A maximum conversion gain of -4.7 dB was measured at 20 K and -12.8 dB at 70 K. &copy; 2013 Crown.
Tao, X.F., Hou, Y.Z., Wang, K.D., He, H.Y. & Guo, Y.J. 2013, 'GPP-based soft base station designing and optimization', Journal of Computer Science and Technology, vol. 28, no. 3, pp. 420-428.
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It is generally acknowledged that mobile communication base stations are composed of hardware components such as Field Programming Gate Array (FPGA), Digital Signal Processor (DSP), which promise reliable and fluent services for the mobile users. However, with the increasing demand for energy-efficiency, approaches of low power-consumption and high-flexibility are needed urgently. In this circumstance, General Purpose Processor (GPP) attracts people's attention for its low-cost and flexibility. Benefited from the development of modern GPP in multi-core, Single Instruction Multiple Data (SIMD) instructions, larger cache, etc., GPPs are capable of performing high-density digital processing. In this paper, we compare several software-defined radio (SDR) prototypes and propose the general architecture of GPP-based soft base stations. Then, the schematic design of resource allocation and algorithm optimization in soft base station implementation are studied. As an application example, a prototype of GPP-based soft base station referring to the 3rd Generation Partnership Project (3GPP) Long Term Evolution (LTE) is realized and evaluated. To the best of our knowledge, it is the first Soft-LTE prototype ever reported. In the end, we evaluate the timing performance of the LTE soft base station and a packet loss ratio of less than 0.003 is obtained. &copy; 2013 Springer Science+Business Media New York & Science Press, China.
Huang, X., Guo, Y.J. & Zhang, J.A. 2012, 'Sample rate conversion using B-spline interpolation for OFDM based software defined radios', IEEE Transactions on Communications, vol. 60, no. 8, pp. 2113-2122.
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This paper proposes arbitrary ratio sample rate conversion (SRC) architectures and a simpler B-spline interpolation algorithm for orthogonal frequency division multiplexing (OFDM) based software defined radios (SDRs) with multiband and multi-channel capabilities. Different from conventional standalone digital front-end designs for SDRs, the proposed SRC architectures combine the B-spline interpolation with OFDM modulation and equalization for OFDM transmitter and receiver respectively. With this combined design, the passband droop introduced by the B-spline interpolation can be more efficiently compensated using frequency-domain pre-distortion, instead of conventional time-domain pre-filtering, and hence an overall system complexity reduction is achieved. A novel multi-period B-spline interpolation and re-sampling structure is then constructed, and an interpolation algorithm with lower implementation complexity than that of the conventional Farrow structure is further developed. The SRC performance is also analysed by deriving the signal-to-peak distortion ratio formulas which can be used as design tools for determining the required orders of B-splines in the OFDM transmitter and receiver respectively. Finally, SRC examples used in a high-speed multiband multi-channel microwave backhaul system are given and compared with conventional polyphase filterbank interpolation to demonstrate the practicality and performance of the proposed SRC architectures and interpolation algorithm
Yang, X., Tao, X., Guo, Y.J., Huang, X. & Cui, Q. 2012, 'Subsampled circulant matrix based analogue compressed sensing', Electronics Letters, vol. 48, no. 13, pp. 767-768.
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The modulated wideband converter (MWC) is an attractive analogue compressed sensing technique proposed recently. Unfortunately, the MWC has high hardware complexity owing to its parallel structure. To reduce the complexity, proposed is a novel subsampled circulant matrix based analogue compressed sensing (SCM-ACS) scheme. Using the cyclic shifts of the Zadoff-Chu sequence, the SCM-ACS scheme reduces the number of physical parallel channels from m to 1 with larger processing time, where m ranges from several dozen to several hundred. It is proved that when m=O(r log 2 M log 3 r) the measurement matrix of the SCM-ACS scheme satisfies the restricted isometry property condition with probability 1-M -O (1), where M is the length of the Zadoff-Chu sequence, and r is the sparsity of the input signal. Simulation results show that the SCM-ACS scheme outperforms the MWC on recovery performance. &copy; 2012 The Institution of Engineering and Technology.
Guo, Y.J., Huang, X. & Dyadyuk, V. 2012, 'A hybrid adaptive antenna array for long-range mm-wave communications', IEEE Antennas and Propagation Magazine, vol. 54, no. 2, pp. 271-282.
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Owing to the availability of wide (GHz) bandwidth at mm-wave frequencies, there is growing interest in high-speed mm-wave communications systems. However, the limited physical size and volume of the antenna and RF system do pose several major challenges. This article presents CSIRO's research on hybrid adaptive antenna arrays and associated digital-beamforming algorithms for achieving high-speed long-range communications in the millimeter-wave frequency bands. The hybrid antenna array consists of a number of analog subarrays, followed by a digital beamformer. Two subarray configurations - the interleaved subarray and the side-by-side subarray - are described. The adaptive angle-of-arrival (AoA) estimation and beamforming algorithms in both the time and frequency domains are discussed. The performance of the system was evaluated by simulations. An early stage proof-of-concept adaptive antenna array prototype in the 71 to 76 GHz E band is presented. &copy; 2011 IEEE.
Huang, X., Guo, Y.J., Zhang, A. & Dyadyuk, V. 2012, 'A multi-gigabit microwave backhaul', Communications Magazine, IEEE, vol. 50, pp. 122-129.
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Zhang, J.A., Huang, X., Cantoni, A. & Guo, Y.J. 2012, 'Sidelobe suppression with orthogonal projection for multicarrier systems', Communications, IEEE Transactions on, vol. 60, pp. 589-599.
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Cheng, P., Gui, L., Rui, Y., Guo, Y.J., Huang, X. & Zhang, W. 2012, 'Compressed sensing based channel estimation for two-way relay networks', IEEE Wireless Communications Letters, vol. 1, no. 3, pp. 201-204.
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In this letter, a novel channel estimation scheme based on compressed sensing (CS) theory is proposed for two-way relay networks (TWRN) in sparse frequency-selective fading channels. Unlike point-to-point systems, applying CS theory to sparse channel estimation in TWRN is much more challenging since the equivalent channels (terminal-relay-terminal) may be no longer sparse due to the linear convolutional operation. To solve this problem, instead of directly estimating the equivalent channels, a linear precoding based method is designed to firstly separate the individual channels between the terminals and the relay from the equivalent channels. CS theory is then applied to the time-domain channel estimation with much smaller number of pilot symbols. This scheme enables accurate channel estimation for TWRN with significant overhead reduction. Extensive numerical results are provided to substantiate the effectiveness of the proposed method. &copy; 2012 IEEE.
Huang, X., Jay Guo, Y. & Dyadyuk, V. 2012, 'Multi-gigabit wireless backhauls for broadband networks', Telecommunications Journal of Australia, vol. 62, no. 1, pp. 1-11.
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With the emergence of next generation broadband wireless access and mobile systems, huge demands are being placed on the backhaul infrastructure. As cost-effective alternatives to traditional copper and fibre backhauls, high speed and long range wireless backhauls become more and more attractive. However, current existing wireless backhaul systems neither provide sufficiently high speed nor meet the requirements to achieve both high speed and long range at the same time. Multi-gigabit data rates can be obtained using millimetre-wave (mmwave) point-to-point systems, but the practical transmission range is still the major weakness. Traditional microwave systems can achieve longer transmission range, but the data rates are limited to a few hundred Mega bits per second only. In this article, a review on the demand for multi-gigabit wireless backhauls is given and the benefits of wireless backhauls are described. The radio propagation characteristics in both mm-wave and microwave frequency bands are provided to show the difference in transmission range for wireless backhauls in the two different bands. The state-of-the-art mm-wave and microwave technologies currently being developed at the Commonwealth Scientific and Industrial Research Organisation (CSIRO) are introduced to illustrate CSIRO's technology leadership in high speed and long range broadband wireless backhaul systems. It is hoped that the article will stimulate further research interest and industry development.
Yang, X., Tao, X., Cui, Q. & Guo, Y.J. 2012, 'Interference-constrained adaptive simultaneous spectrum sensing and data transmission scheme for unslotted cognitive radio network', Eurasip Journal on Wireless Communications and Networking, vol. 2012.
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Cognitive radio (CR) is widely recognized as a novel approach to improve the spectrum efficiency. However, there exists one problem needed to be resolved urgently, that is the two conflicting goals in CR network: one is to minimize the interference to primary (licensed) system; the other is to maximize the throughput of secondary (unlicensed) system. Meanwhile, the secondary user (SU) has to monitor the spectrum continuously to avoid the interference to primary user (PU), thus the throughput of the secondary system is affected by how often and how long the spectrum sensing is performed. Aiming to balance the two conflicting goals, this article proposes a novel Interference-Constrained Adaptive Simultaneous spectrum Sensing and data Transmission (ICASST) scheme for unslotted CR network, where SUs are not synchronized with PUs. In the ICASST scheme, taking advantage of the statistic information of PU's activities, the data transmission time is adaptively adjusted to avoid the interference peculiar to unslotted CR network; the operation of spectrum sensing is moved to SU receiver from SU transmitter to increase the data transmission time and hence improve the throughput of SU. Simulation results validate the efficiency of ICASST scheme, which significantly increases the throughput of secondary system and decreases the interference to PU simultaneously. &copy; 2012 Yang et al.
Guzmán-Quirós, R., Gómez-Tornero, J.L., Weily, A.R. & Guo, Y.J. 2012, 'Electronic full-space scanning with 1-D fabry-pérot LWA using electromagnetic band-gap', IEEE Antennas and Wireless Propagation Letters, vol. 11, pp. 1426-1429.
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A novel mechanism to obtain full-space electronic scanning from a half-space scanning one-dimensional (1-D) Fabry-P&eacute;rot (FP) leaky-wave antenna (LWA) is proposed and experimentally demonstrated in this letter. By using a central feed that divides the structure into two independently controlled leaky lines, one each side, and making use of the electromagnetic band-gap (EBG) region of the FP resonator, the antenna can be electronically tuned to operate in three different regimes: backward scanning, forward scanning, and broadside radiation. Leaky-mode dispersion theory and experimental results of a fabricated prototype demonstrate a continuous electronic scanning from-25&deg; to +25&deg; at 5.5 GHz. &copy; 2011 IEEE.
Guzmán-Quirós, R., Gómez-Tornero, J.L., Weily, A.R. & Guo, Y.J. 2012, 'Electronically steerable 1-d fabry-perot leaky-wave antenna employing a tunable high impedance surface', IEEE Transactions on Antennas and Propagation, vol. 60, no. 11, pp. 5046-5055.
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&copy; 2012 IEEE. A novel fixed-frequency electronically-steerable one-dimensional (1-D) leaky-wave antenna is presented. The antenna is based on a parallel-plate waveguide loaded with a planar partially reflective surface and a tunable high impedance surface (HIS), which creates a 1-D Fabry-Perot leaky-waveguide. The tunable HIS consists of printed patches loaded with varactor diodes that allow the electronic tuning of the cavity resonance condition. Using a simple Transverse Equivalent Network, it is theoretically shown how the variation of the varactors' junction capacitance allows the scanning of the antenna pointing angle from broadside towards the endfire direction at a fixed frequency. Experimental results of an antenna prototype operating at 5.6 GHz are reported, demonstrating that the new reconfigurable leaky-wave antenna can provide electronic beam scanning in an angular range from 9&deg; to 30&deg;.
Wenzhi, W., Sheng, Y., Xianling, L., Ronghong, J., Bird, T.S., Guo, Y.J. & Junping, G. 2012, 'Even- and odd-mode analysis of thick and wide transverse slot in waveguides based on a variational method', IEEE Transactions on Microwave Theory and Techniques, vol. 60, no. 11, pp. 3349-3358.
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Based on a new variational method, an even- and odd-mode analysis of transverse coupling slot between waveguides is presented. The proposed method is capable of dealing with slots of finite wall thickness. It uses multiple incident waves with symmetry to simplify the field distribution in the vicinity of the slot, enabling the adoption of one-expansion-term trial functions with sufficient accuracy, even in the instance of wide slots. Analytical solutions are provided, and the calculated results demonstrate excellent agreement with those of numerical simulation. The computation time with the new formulation is, however, significantly shorter. &copy; 1963-2012 IEEE.
Zhang, T., Du, J., Guo, Y.J. & Sun, X. 2012, 'Design and integration of HTS filters with a Josephson device', Superconductor Science and Technology, vol. 25, no. 10.
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A high-temperature superconducting (HTS) Josephson frequency down-converting module is demonstrated. An HTS monolithic frequency down-converting circuit and a biasing circuit board for the Josephson device are packaged into the module. The monolithic circuit consists of HTS filters and a Josephson oscillator-mixer device, integrated on a single 10mm20mm chip of Y Ba 2 Cu 3 O 7x (YBCO) film on MgO substrate. A compact, low-loss HTS step-impedance low-pass filter was designed for the intermediate frequency (IF) output port. The modeling, simulation and measurement results of the HTS low-pass filter are presented in this paper. The frequency response and dynamic range of the on-chip integrated HTS down-converting module are also described. &copy; 2012 IOP Publishing Ltd.
Garcia-Vigueras, M., Gomez-Tornero, J.L., Goussetis, G., Weily, A.R. & Guo, Y.J. 2012, 'Efficient synthesis of 1-D fabry-perot antennas with low sidelobe levels', IEEE Antennas and Wireless Propagation Letters, vol. 11, pp. 869-872.
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A novel technique for the efficient synthesis of one-dimensional (1-D) Fabry-Perot leaky-wave antennas with low sidelobe levels is described. It is based on the study of the reflection characteristics presented by the two periodic surfaces that form the cavity. The synthesis technique avoids the search for modal solutions in the complex plane, which is typically needed to characterize the dispersion of the leaky modes associated with the antenna geometry. Instead, it involves the solution of two simple equations, so that the desired aperture distribution (amplitude and phase) can be directly synthesized. Numerical and experimental results show that the method can be used to efficiently synthesize 1-D Fabry-Perot low sidelobe leaky-wave antennas for any desired scanning angle. &copy; 2002-2011 IEEE.
Zhang, T., Du, J., Guo, Y.J. & Sun, X.W. 2012, 'On-chip integration of HTS bandpass and lowpass filters with Josephson mixer', Electronics Letters, vol. 48, no. 12, pp. 729-731.
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A compact high-T c superconducting (HTS) monolithic downconverter is presented. The HTS passive and active devices are integrated on one single chip to achieve compactness and high coupling efficiency. The downconverter consists of a HTS YBa 2 Cu 3 O 7-x (YBCO) bandpass filter for RF input, a lowpass filter for IF output, and a self-pumped step-edge Josephson heterodyne mixer fabricated on a 20 10mm MgO substrate. Characterisations of the HTS filters and the frequency response of the on-chip integrated downconverter are reported. The results demonstrate the potential of the HTS downconverter for applications in wireless communications. &copy; 2012 The Institution of Engineering and Technology.
Du, J., Zhang, T., MacFarlane, J.C., Guo, Y.J. & Sun, X.W. 2012, 'Monolithic high-temperature superconducting heterodyne Josephson frequency down-converter', Applied Physics Letters, vol. 100, no. 26.
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A monolithic microwave integrated circuit (MMIC) frequency down-converter based on a compact high-T c superconducting (HTS) device is demonstrated. The on-chip integrated HTS down-converter consists of a 7-9 GHz bandpass filter for RF input, a lowpass filter for intermediate frequency output, and a self-pumped Josephson heterodyne mixer. All the above passive and active components are fabricated on a single 10 mm 20 mm chip of YBa 2 Cu 3 O 7-x film on MgO substrate. Characterization of this MMIC HTS down-converter in terms of frequency response, conversion gain, frequency-tuneability, bias dependence, dynamic range, linearity, and intrinsic noise are presented in this paper. &copy; 2012 Crown.
Cai, Y., Guo, Y.J. & Qin, P.-.Y. 2012, 'Frequency switchable printed Yagi-Uda dipole sub-array for base station antennas', Antennas and Propagation, IEEE Transactions on, vol. 60, pp. 1639-1642.
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Qin, P.-.Y., Guo, Y.J., Weily, A.R. & Liang, C.-.H. 2012, 'A pattern reconfigurable U-slot antenna and its applications in MIMO systems', Antennas and Propagation, IEEE Transactions on, vol. 60, pp. 516-528.
Du, J., MacFarlane, J.C., Zhang, T., Cai, Y. & Guo, Y.J. 2012, 'Self-pumped HTS Josephson heterodyne tunable mixer', Superconductor Science and Technology, vol. 25, no. 2.
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Experimental evaluation of a high-temperature superconducting Josephson heterodyne mixer based on a resistive-SQUID configuration is reported. The device consists of two YBa 2 Cu 3 O 7-x step-edge Josephson junctions connected via a small resistor in an otherwise superconducting loop. It has been previously shown to generate a heterodyne oscillation, which is frequency-tunable by a control current through the resistor. Under certain conditions, this device can operate as a frequency-tunable heterodyne mixer (down-converter) in the presence of an RF signal. In this paper, we describe the operation of the autonomous Josephson mixerlocal oscillator device and present the experimental results on the mixer performances in terms of the junction currentvoltage characteristics, the frequency tunability, linearity, and dynamic range as well as their temperature dependence for signal frequencies from 1 to 5GHz. &copy; 2012 IOP Publishing Ltd.
Parr, G., Hailes, S., How, J.P., McGeehan, J. & Guo, Y.J. 2012, 'Guest editorial: Communications challenges and dynamics for unmanned autonomous vehicles', IEEE Journal on Selected Areas in Communications, vol. 30, no. 5, pp. 849-851.
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Cai, Y., Guo, Y.J. & Bird, T.S. 2012, 'A frequency reconfigurable printed yagi-uda dipole antenna for cognitive radio applications', IEEE Transactions on Antennas and Propagation, vol. 60, no. 6, pp. 2905-2912.
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A frequency reconfigurable printed Yagi-Uda antenna is presented for cognitive radio applications. A 46% continuous frequency tuning bandwidth is obtained by loading the driver dipole arms and four directors with varactor diodes. This configuration allows a high-gain and an almost constant end-fire pattern to be maintained while the antenna operating frequency is tuned. A parametric study was undertaken considering the inter-director spacing, director length tapering, and reflector geometry. It was found possible over the band that the front-to-back ratio is > 16 dB, the sidelobe level is < -14 dB and the cross polarization levels in the principal planes are < - 15.5 dB. From 1-dB compression point measurements, the maximum input power of the antenna with the present diodes is limited to 17.6 dBm at 700 MHz. This suggests that reconfigurable antennas which use active components should have an IIP3 specification placed on them. The frequency selective feature of the antenna makes it as an attractive user terminal antenna for fixed point-to-multipoint cognitive radio enabled broadband wireless access. &copy; 2012 IEEE.
Du, J., MacFarlane, J.C., Pegrum, C.M., Zhang, T., Cai, Y. & Guo, Y.J. 2012, 'A self-pumped high-temperature superconducting Josephson mixer: Modelling and measurement', Journal of Applied Physics, vol. 111, no. 5.
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We have recently developed a high-temperature superconducting (HTS) Josephson self-pumped mixer with an on-chip heterodyne local oscillator. The device is based on HTS step-edge junction technology and a resistive- superconducting quantum interference device (RSQUID) configuration. The heterodyne local oscillator and mixer output are frequency-tunable from below 10 MHz to 5 GHz by a control current. The performance of the autonomous Josephson mixer-local oscillator has been experimentally evaluated in terms of the current-voltage characteristics, intermediate frequency (IF)-tunable bandwidth, operation range, linearity, bias current, and temperature dependence of the IF output (or mixer conversion efficiency). We find the results are in good overall agreement with numerical simulation. &copy; 2012 American Institute of Physics.
Ye, S., Liang, X., Wang, W., Jin, R., Geng, J., Bird, T.S. & Guo, Y.J. 2012, 'High-Gain planar antenna arrays for mobile satellite communications', IEEE Antennas and Propagation Magazine, vol. 54, no. 6, pp. 256-268.
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Two large and low-profile panel antenna arrays, used as receiving and transmitting antennas for mobile satellite communications, are described. The receiving and transmitting arrays have overall dimensions of 120 cm 20.7 cm 1.3cm and 107.5 cm 20.4 cm 1.7 cm, respectively. They exhibit high gains and adequate efficiencies, due to integrated array designs. For the receiving panel array, a method using a number of high-efficiency subarrays, combined with a novel active integrated global feed network, is proposed. For the transmitting panel array, a number of high-efficiency subarrays, together with a novel compact waveguide feed network, is employed. Based on the above techniques, two large panel antenna arrays were successfully developed. We present the detailed designs of the subarrays, the passive and active feed networks, and the vertical transitions. Simulated and experimental results showed that the designed receiving and transmitting panel arrays achieved measured gains and efficiencies of 34.1 dBi and 48.2%, and 33.5 dBi and 36.3%, respectively, in each band. This indicated that the proposed antenna panels are good candidates for future satellite communications applications. &copy; 2011 IEEE.
Zheng, F.C., Correia, L., Jay Guo, Y., O'Farrell, T. & Madan, R. 2012, 'Guest Editorial', Journal of Communications, vol. 7, no. SPL.ISS. 10, pp. 713-715.
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Huang, X. & Guo, Y.J. 2011, 'Frequency-domain AoA estimation and beamforming with wideband hybrid arrays', IEEE Transactions on Wireless Communications, vol. 10, no. 8, pp. 2543-2553.
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High speed long range millimetre-wave (mm-wave) links can be achieved by using wideband hybrid antenna arrays of sub-arrays. Due to the array architecture difference, conventional wideband angle-of-arrival (AoA) estimation and beamforming techniques are not applicable to such wideband hybrid arrays. Targeted at point-to-point line-of-sight wireless transmission in the 70/80 GHz E bands, a unified frequency-domain AoA estimation and beamforming algorithm suitable for large scale wideband hybrid arrays of both interleaved and side-by-side sub-arrays is proposed in this paper. The AoA estimation performance is analyzed by deriving a recursive modified Cramr-Rao bound (MCRB). The effect of mutual coupling among antenna elements on the estimation performance is also considered for the hybrid array of side-by-side sub-arrays. The analytical results can be used to determine system parameters according to required system specifications. Simulation results show that the proposed AoA estimation algorithm is robust against practical impairments, and the frequency dependency of the array pattern is significantly reduced after digital beamforming. Simulated mean square errors of AoA estimation are also compared with the analytical bounds, showing that the derived recursive MCRB provides a meaningful indication to the AoA estimation performance. &copy; 2006 IEEE.
Ma, M., Huang, X., Jiao, B. & Guo, Y. 2011, 'Optimal orthogonal precoding for spectral leakage suppression in DFT-based systems', IEEE Transactions on Communications, vol. 59, no. 3, pp. 844-853.
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García-Vigueras, M., Gómez-Tornero, J.L., Goussetis, G., Weily, A.R. & Guo, Y.J. 2011, 'Enhancing frequency-scanning response of leaky-wave antennas using high-impedance surfaces', IEEE Antennas and Wireless Propagation Letters, vol. 10, pp. 7-10.
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The use of high-impedance surfaces (HISs) to increase the frequency-scanning sensitivity of hollow leaky-wave antennas (LWAs) is presented. The LWA consists of a hollow rectangular waveguide with one of its narrow walls replaced by a partially reflective surface, and it is loaded with a metallodielectric HIS to increase its beam-scanning response. Theoretical results based on a simple transverse equivalent network illustrate the physical mechanism responsible for the improvement, and they are verified by experiments on a prototype working in the 11-16 GHz band. &copy; 2006 IEEE.
Gómez-Tornero, J.L., Quesada-Pereira, F., Alvarez-Melcón, A., Goussetis, G., Weily, A.R. & Guo, Y.J. 2011, 'Frequency steerable two dimensional focusing using rectilinear leaky-wave lenses', IEEE Transactions on Antennas and Propagation, vol. 59, no. 2, pp. 407-415.
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The concept of frequency steerable two-dimensional electromagnetic focusing by using a tapered leaky-wave line source embedded in a parallel-plate medium is presented. Accurate expressions for analyzing the focusing pattern of a rectilinear leaky-wave lens (LWL) from its constituent leaky-mode tapered propagation constant are described. The influence of the main LWL structural parameters on the synthesis of the focusing pattern is discussed. The ability to generate frequency steerable focusing patterns has been demonstrated by means of an example involving a LWL in hybrid waveguide printed-circuit technology and the results are validated by a commercial full-wave solver. &copy; 2010 IEEE.
Cai, Y. & Guo, Y.J. 2011, 'A frequency-agile compact array with a reconfigurable decoupling and matching network', IEEE Antennas and Wireless Propagation Letters, vol. 10, pp. 1031-1034.
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A new frequency-agile compact antenna array incorporating a reconfigurable decoupling and matching network (DMN) is presented. The array consists of two printed monopole antennas, each loaded with a p-i-n diode. By changing the p-i-n diode states through an inductive biasing line, the array operating frequency can be tuned to the 2.5-or 3.5-GHz band. The array interelement spacing is chosen to be as small as 0.05 0 at 2.5 GHz, which results in a strong mutual coupling between antenna ports. A reconfigurable DMN is proposed to reduce the mutual coupling when the array frequency is switched. Measured results show that the use of the DMN realizes a matched (S 11 -10 dB) and decoupled (S 21 -20 dB) bandwidth of 150 and 160 MHz in the lower and higher bands, respectively. In addition, compared to the strongly coupled array, at least 9% antenna total efficiency improvement is measured over a 125-MHz bandwidth in both the lower and the higher bands. The effect of the ohmic loss in the DMN on the antenna correlation is also investigated. &copy; 2011 IEEE.
Gómez-Tornero, J.L., Weily, A.R. & Guo, Y.J. 2011, 'Rectilinear leaky-wave antennas with broad beam patterns using hybrid printed-circuit waveguides', IEEE Transactions on Antennas and Propagation, vol. 59, no. 11, pp. 3999-4007.
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A theoretical study on the design of broadbeam leaky-wave antennas (LWAs) of uniform type and rectilinear geometry is presented. A new broadbeam LWA structure based on the hybrid printed-circuit waveguide is proposed, which allows for the necessary flexible and independent control of the leaky-wave phase and leakage constants. The study shows that both the real and virtual focus LWAs can be synthesized in a simple manner by tapering the printed-slot along the LWA properly, but the real focus LWA is preferred in practice. Practical issues concerning the tapering of these LWA are investigated, including the tuning of the radiation pattern asymmetry level and beamwidth, the control of the ripple level inside the broad radiated main beam, and the frequency response of the broadbeam LWA. The paper provides new insight and guidance for the design of this type of LWAs. &copy; 2011 IEEE.
Qin, P.-.Y., Guo, Y.J., Cai, Y., Dutkiewicz, E. & Liang, C.-.H. 2011, 'A reconfigurable antenna with frequency and polarization agility', Antennas and Wireless Propagation Letters, IEEE, vol. 10, pp. 1373-1376.
García-Vigueras, M., Gómez-Tornero, J.L., Goussetis, G., Weily, A.R. & Guo, Y.J. 2011, '1D-leaky wave antenna employing parallel-plate waveguide loaded with PRS and HIS', IEEE Transactions on Antennas and Propagation, vol. 59, no. 10, pp. 3687-3694.
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A new type of one-dimensional leaky-wave antenna (LWA) with independent control of the beam-pointing angle and beamwidth is presented. The antenna is based on a simple structure composed of a bulk parallel-plate waveguide (PPW) loaded with two printed circuit boards (PCBs), each one consisting of an array of printed dipoles. One PCB acts as a partially reflective surface (PRS), and the other grounded PCB behaves as a high impedance surface (HIS). It is shown that an independent control of the leaky-mode phase and leakage rate can be achieved by changing the lengths of the PRS and HIS dipoles, thus resulting in a flexible adjustment of the LWA pointing direction and directivity. The leaky-mode dispersion curves are obtained with a simple Transverse Equivalent Network (TEN), and they are validated with three-dimensional full-wave simulations. Experimental results on fabricated prototypes operating at 15 GHz are reported, demonstrating the versatile and independent control of the LWA performance by changing the PRS and HIS parameters. &copy; 2011 IEEE.
Huang, X., Guo, Y.J. & Bunton, J.D. 2010, 'A hybrid adaptive antenna array', IEEE Transactions on Wireless Communications, vol. 9, no. 5, pp. 1770-1779.
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Owing to the excessive demand on signal processing and space constraint, a full digital implementation of a large adaptive antenna array at millimeter wave frequencies is very challenging. Targeted at long range high data rate point-topoint link in the 70/80 GHz bands, a novel hybrid adaptive antenna array which consists of analogue subarrays followed by a digital beamformer is presented in this paper to overcome the digital implementation difficulty. Two subarray configurations, the interleaved subarray and the side-by-side subarray, are proposed, and two Doppler resilient adaptive angle-of-arrival estimation and beamforming algorithms, the differential beam tracking (DBT) and the differential beam search (DBS), are developed. Simulation results on the DBT and DBS performance are provided using a 64 element hybrid planar array of four 4 by 4 element subarrays with the two subarray configurations, respectively. Recursive mean square error (MSE) bounds of the developed algorithms are also analyzed and compared with simulated MSEs. &copy; 2006 IEEE.
Ma, M., Huang, X. & Guo, Y.J. 2010, 'An interference self-cancellation technique for SC-FDMA systems', IEEE Communications Letters, vol. 14, no. 6, pp. 512-514.
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A new interference self-cancellation (ISC) method for Single Carrier-FDMA (SC-FDMA) systems is proposed to mitigate the inter-user interference caused by frequency offset or Doppler effect. By transmitting a compensation symbol at the first symbol location in each resource block, the energy leakage can be significantly suppressed. With little bandwidth and power sacrifice, the proposed method can greatly improve the system robustness against frequency offset. Simulation results show that the signal-to-interference ratio (SIR) can be improved by 7 dB on average for the entire system band, and up to 11.7 dB for an individual user. &copy; 2010 IEEE.
Qin, P.-.Y., Guo, Y.J. & Liang, C.-.H. 2010, 'Effect of antenna polarization diversity on MIMO system capacity', Antennas and Wireless Propagation Letters, IEEE, vol. 9, pp. 1092-1095.
Qin, P.-.Y., Weily, A.R., Guo, Y.J., Bird, T.S. & Liang, C.-.H. 2010, 'Frequency reconfigurable quasi-Yagi folded dipole antenna', Antennas and Propagation, IEEE Transactions on, vol. 58, pp. 2742-2747.
Cai, Y., Guo, Y.J. & Weily, A.R. 2010, 'A frequency-reconfigurable quasi-Yagi dipole antenna', IEEE Antennas and Wireless Propagation Letters, vol. 9, pp. 883-886.
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A new frequency-reconfigurable quasi-Yagi dipole antenna is presented. It consists of a driven dipole element with two varactors in two arms, a director with an additional varactor, a truncated ground plane reflector, a microstrip-to-coplanar-stripline (CPS) transition, and a novel biasing circuit. The effective electrical length of the director element and that of the driven arms are adjusted together by changing the biasing voltages. A 35% continuously frequency-tuning bandwidth, from 1.80 to 2.45 GHz, is achieved. This covers a number of wireless communication systems, including 3G UMTS, US WCS, and WLAN. The length-adjustable director allows the endfire pattern with relatively high gain to be maintained over the entire tuning bandwidth. Measured results show that the gain varies from 5.6 to 7.6 dBi and the front-to-back ratio is better than 10 dB. The H-plane cross polarization is below -15 dB, and that in the E-plane is below -20 dB. &copy; 2006 IEEE.
Qin, P.-.Y., Weily, A.R., Guo, Y.J. & Liang, C.-.H. 2010, 'Polarization reconfigurable U-slot patch antenna', Antennas and Propagation, IEEE Transactions on, vol. 58, pp. 3383-3388.
Qin, P.-.Y., Weily, A.R., Guo, Y.J., Bird, T.S. & Liang, C.-.H. 2010, 'Frequency Reconfigurable Quasi-Yagi Folded Dipole Antenna', IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION, vol. 58, no. 8, pp. 2742-2747.
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Guo, Y.J., Liu, D. & Bird, N.C. 2009, 'Guest editorial for the special issue on antennas and propagation aspects of 60-90 GHz wireless communications', IEEE Transactions on Antennas and Propagation, vol. 57, no. 10 PART 1, pp. 2817-2819.
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Weily, A.R. & Guo, Y.J. 2009, 'Circularly polarized ellipse-loaded circular slot array for millimeter-wave WPAN applications', IEEE Transactions on Antennas and Propagation, vol. 57, no. 10 PART 1, pp. 2862-2870.
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A circularly polarized slot array suitable for millimeter wave WPAN applications is presented. The array uses a new type of circularly polarized element, comprising a circular slot loaded with an elliptical patch, and is fed by a microstrip line. The array is implemented on liquid crystal polymer (LCP), which is both low-loss and low-cost. A total of 8 array elements are used in a 4 2 configuration to achieve a maximum gain target of greater than 14 dBic. Sequential rotation of the elements within each of the 2 2 sub-arrays is used to increase the axial ratio bandwidth. Other novel features of the array are the finite ground plane, and open cavity structure used to support the LCP substrate of the slot array above a reflector plate. Measured and computed results presented for the packaged array confirm its wide impedance, axial ratio, and gain bandwidths. The effect of the packaged array back-short on the measured axial ratio is also discussed. &copy; 2009 IEEE.
Yu, K. & Guo, Y.J. 2009, 'Anchor-free localisation algorithm and performance analysis in wireless sensor networks', IET Communications, vol. 3, no. 4, pp. 549-560.
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A hybrid anchor-free localisation scheme for multihop wireless sensor networks is presented. First, a relatively dense group of nodes is selected as a base, which are localised by using the multidimensional scaling method. Secondly, the robust quads (RQ) method is employed to localise other nodes, following which the robust triangle and radio range (RTRR) approach is used to perform the localisation task. The RQ and the RTRR methods are used alternately until no more nodes can be localised by the two approaches. Simulation results demonstrate that the proposed hybrid localisation algorithm performs well in terms of both accuracy and the success rate of localisation. To evaluate the accuracy of anchor-free localisation algorithms, the authors derive two different accuracy measures: the Cramer-Rao lower bound (CRLB) to benchmark the coordinate estimation errors and the approximate lower bound to benchmark the distance errors. Simulation results demonstrate that both the CRLB and the distance error lower bound provide references for the accuracy of the location algorithms. &copy; 2009 The Institution of Engineering and Technology.
Yu, K. & Guo, Y.J. 2009, 'Anchor global position accuracy enhancement based on data fusion', IEEE Transactions on Vehicular Technology, vol. 58, no. 3, pp. 1616-1623.
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The location information of sensor nodes in wireless sensor networks is crucial for various applications such as emergency rescue operations, environmental monitoring, home automation, and traffic control. In this paper, a new method to improve the anchor location accuracy in wireless sensor networks is proposed based on fusion of Global Positioning System (GPS) measurements and anchor-to-anchor parameter estimates. Novel algorithms are derived to increase the accuracy of anchor locations using both anchor-to-anchor distance and angle-of-arrival (AOA) estimates for both line-of-sight (LOS) and non-LOS (NLOS) scenarios. When using anchor-to-anchor distance estimates in LOS conditions, an optimization-based algorithm is developed. The Cramer-Rao lower bound (CRLB) is derived to benchmark positioning accuracy in 3-D environments with both GPS measurements and anchor-to-anchor parameter estimates, which has not been studied in the literature. Simulation results demonstrate that the proposed algorithms can substantially improve anchor position accuracy, and the performance of the proposed algorithms approaches the CRLB. &copy; 2008 IEEE.
Yu, K., Guo, Y.J. & Hedley, M. 2009, 'TOA-based distributed localisation with unknown internal delays and clock frequency offsets in wireless sensor networks', IET Signal Processing, vol. 3, no. 2, pp. 106-118.
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Locating sensor nodes in an ad hoc wireless sensor network (WSN) is a challenging task. In general, the network nodes are not synchronised and the internal delays within the nodes are unknown. Here, time-of-arrival (TOA)-based localisation is investigated when practical parameters such as clock time offset, clock frequency offset and system internal delay are all involved. The TOA measurements are made between each pair of nodes that are within radio range. First, an efficient frequency offset (FO) estimation algorithm is derived. Then, a two-stage localisation scheme is proposed. In the first stage, localisation starts from the nodes with the largest numbers of neighbouring anchors and priority is always given to nodes with more neighbouring anchors and/or localised nodes. In the second stage, the locations of all neighbouring nodes are exploited to improve location accuracy. Two iterative algorithms are developed: the Taylor series-based least squares (TS-LS) method and the sequential quadratic programming (SQP) optimisation method. During the localisation process, a number of measures are taken to ensure the reliability of each location estimate to avoid abnormal errors and reduce error propagation. The Cramer-Rao lower bound is also derived to benchmark the location accuracy. &copy; The Institution of Engineering and Technology 2009.
Sharp, I., Yu, K. & Guo, Y.J. 2009, 'Peak and leading edge detection for time-of-arrival estimation in band-limited positioning systems', IET Communications, vol. 3, no. 10, pp. 1616-1627.
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The performance of the peak and leading edge detection methods for time-of-arrival (TOA) estimation in band-limited systems is examined. Analytical expressions for the detection performance in the presence of both random noise and multipath interference are derived. A dimensionless performance factor is presented that allows simple comparisons of the TOA estimation algorithms. These equations allow the performance tradeoff analysis to be undertaken without the need for simulations. It is shown that the leading edge detection method has significantly better multipath mitigation characteristics than the peak detection one, but at the expense of inferior noise performance. &copy; 2009, The Institution of Engineering and Technology.
Li, Y., Archer, J.W., Tello, J., Rosolen, G., Ceccato, F., Hay, S.G., Hellicar, A. & Guo, Y.J. 2009, 'Performance evaluation of a passive millimeter-wave imager', IEEE Transactions on Microwave Theory and Techniques, vol. 57, no. 10, pp. 2391-2405.
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A cross-correlating 186-GHz passive millimeter-wave imager has been built. The key components in the signal processing hardware are two 186-GHz receivers and a broadband complex correlator. To evaluate the performance of this imager, its point-spread function, beam pattern, baseline vector, and their variations with the scanning direction have been experimentally measured and derived. Some of these results are needed for optimizing the imager's parameter settings. Others are required for implementing the modulated-beam and modulated-scene algorithms proposed in a previous paper dealing with the imager's fringe in its point-spread function. These results will also reveal any problems in the construction process of the imager. The theoretical bases for these measurements are analyzed. Novel algorithms for deriving each antenna's point-spread function and beam pattern, as well as the imager's baseline vector from the measurement results of the imager's point-spread function and beam pattern are proposed and successfully applied in the measurements. Experimental results are presented and discussed. &copy; 2009 IEEE.
Tang, X., Ma, M., Ostry, D.I., Jiao, B. & Guo, Y.J. 2009, 'Characterizing impulsive network traffic using truncated -stable processes', IEEE Communications Letters, vol. 13, no. 12, pp. 980-982.
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It has been recently recognized that aggregated traffic in a variety of networks exhibits a similar impulsiveness over a wide range of aggregation levels, but approaches a Gaussian distribution in the limit as the aggregation level grows. Although several traffic models have been proposed in the past decade, their accuracy in simultaneously characterizing the above properties still needs to be further improved. In this letter, we propose a truncated -stable process model which is able to capture the impulsiveness of observed network traffic as well as its tendency toward the Gaussian distribution with aggregation. An inherent physical mechanism is also proposed to give insight into the underlying meaning of the proposed model. Simulation results show that the proposed process achieves close agreement with real traffic and outperforms previous models. &copy; 2006 IEEE.
Sharp, I., Yu, K. & Guo, Y.J. 2009, 'GDOP analysis for positioning system design', IEEE Transactions on Vehicular Technology, vol. 58, no. 7, pp. 3371-3382.
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Geometric dilution of precision (GDOP) has been widely used as an accuracy metric for navigation and tracking systems. Since high accuracy in a positioning system requires both accurate measurement of the range and a good geometric relationship between the mobile device and the measuring points, the analysis of GDOP is an essential feature in determining the performance of a positioning system. In this paper, we perform GDOP analysis to obtain concise analytical expressions for a number of scenarios, which are generally applicable to geometries where the mobile device is surrounded by base stations. Comparison of the analytical results with simulations using the typical geometries of indoor positioning systems shows good agreement, except when the mobile position is close to a base station. This effect is a consequence of the ranging errors being a significant proportion of the range in short-range tracking systems and discontinuities in GDOP at the base station. The results provide useful information for the design and testing of tracking systems, as well as for the determination of the geometric deployment of base stations for good GDOP in the coverage area. &copy; 2009 IEEE.
Yu, K. & Guo, Y.J. 2009, 'Statistical NLOS identification based on AOA, TOA, and signal strength', IEEE Transactions on Vehicular Technology, vol. 58, no. 1, pp. 274-286.
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Nonline-of-sight (NLOS) propagation is one of the challenges in radio positioning. Significant attention has been drawn to the mitigation of the NLOS effect in recent years. This paper focuses on the identification of NLOS conditions by employing the statistical decision theory. A Neyman-Pearson (NP) test method is first derived for scenarios where either 1-D or 2-D angular measurements are provided. A time-of-arrival (TOA) based method is then developed under idealized conditions to provide a performance reference. In the presence of both TOA and received signal strength (RSS) measurements, a joint identification method is derived to efficiently exploit the TOA and RSS measurements. Analytical expressions of the probability of detection (POD) and the probability of false alarm (PFA) are derived for all the scenarios considered. Two theorems and one corollary regarding the line-of-sight (LOS) conditions based on the angle of arrival (AOA) are also presented, and the proofs are provided. Simulation results demonstrate that the proposed methods perform well, and the joint TOA- and RSS-based method considerably outperforms the TOA-based methods. The proposed methods are robust to the model errors, as demonstrated through simulations. It is also shown that the analytical results agree well with the simulated ones. &copy; 2009 IEEE.
Yu, K. & Guo, Y.J. 2008, 'Improved positioning algorithms for nonline-of-sight environments', IEEE Transactions on Vehicular Technology, vol. 57, no. 4, pp. 2342-2353.
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Nonline-of-sight (NLOS) conditions pose a major challenge to radio positioning. In this paper, a constrained-optimization-based location algorithm is proposed to jointly estimate the unknown location and bias by using the sequential quadratic programming (SQP) algorithm. This method does not rely on any prior statistics information, and simulation results show that the proposed method considerably outperforms existing methods. To reduce the complexity of the SQP-based algorithm, we further propose a Taylor-series expansion-based linear quadratic programming (TS-LQP) algorithm. It is demonstrated that the computational complexity of the TS-LQP algorithm is only a fraction of that of the SQP algorithm, whereas the accuracy loss is limited. Also, maximum-likelihood (ML) algorithms that are suited for different NLOS error statistics are developed under several circumstances when there are different levels of a priori information. The analytical performance of the ML estimation (MLE) is investigated. Moreover, analytical expressions to approximate the variance of the MLE with and without model parameter mismatches are derived. Simulation results show that the approximate variance can be used as a better accuracy measure than the Cramer-Rao lower bound (CRLB). &copy; 2008 IEEE.
Weily, A.R., Bird, T.S. & Guo, Y.J. 2008, 'A reconfigurable high-gain partially reflecting surface antenna', IEEE Transactions on Antennas and Propagation, vol. 56, no. 11, pp. 3382-3390.
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A high-gain partially reflective surface (PRS) antenna with a reconfigurable operating frequency is presented. The operating frequency is electronically tuned by incorporating an array of phase agile reflection cells on a thin substrate above the ground plane of the resonator antenna, where the reflection phase of each cell is controlled by the bias voltage applied to a pair of varactor diodes. The new configuration enables continuous tuning of the antenna from 5.2 GHz to 5.95 GHz using commercially available varactor diodes, thus covering frequencies typically used for WLAN applications. Both the PRS and phase agile cell are analyzed, and theoretical and measured results for gain, tuning range, and radiation patterns of the reconfigurable antenna are described. The effect of the varactor diode series resistance on the performance of the antenna is also reported. &copy; 2008 IEEE.
Li, Y., Sharp, I., Hedley, M., Ho, P. & Guo, Y.J. 2007, 'Single- and double-difference algorithms for position and time-delay calibration of transducer-elements in a sparse array.', IEEE Trans Ultrason Ferroelectr Freq Control, vol. 54, no. 6, pp. 1188-1198.
A method for the calibration of the position and time delay of transducer elements in a large, sparse array used for underwater, high-resolution, ultrasound imaging has been described in a previous work. This algorithm is based on the direct algorithm used in the global positioning system (GPS), but the wave propagation speed is treated as one of the to-be-calibrated parameters. In this article, the performance of two other commonly used GPS algorithms, namely the single-difference algorithm and the double-difference algorithm, is evaluated. The calibration of the propagation speed also is integrated into these two algorithms. Furthermore, a novel, least-squares method is proposed to calibrate the time delay associated with each transducer element for these two algorithms. The performances of these algorithms are theoretically analyzed and evaluated using numerical analysis and simulation study. The performance of the direct algorithm, the single-difference algorithm, and the double-difference algorithm is compared. It was found that the single-difference algorithm has the best performance among the three algorithms for the current application, and it is capable of calibrating the position and time delay of transducer elements to an accuracy of one-tenth of a wavelength.
Peng, M., Guo, Y.J. & Barton, S.K. 2001, 'Multiuser detection of asynchronous CDMA with frequency offset', IEEE Transactions on Communications, vol. 49, no. 6, pp. 952-960.
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This letter presents a near-far resistant detection scheme for asynchronous code-division multiple access with frequency offset. Based on a one-shot technique and Taylor expansion, a zeroth-order and a first-order one-shot linear decorrelating detector (LDD) are proposed. The zeroth-order LDD has simple architecture but suffers performance degradation for large frequency offset. The first-order one-shot LDD, with increased complexity, has very good near-far resistant property even for large frequency offset. Two versions of the first-order one-shot LDD are investigated according to different Taylor expansion approaches. The feasibility of the proposed detectors is demonstrated by computer simulations.
Johnson, I.R., Tellambura, C., Guo, Y.J. & Barton, S.K. 2000, 'HIPERLAN receiver design issues: noise performance and frequency offset compensation', International Journal of Wireless Information Networks, vol. 7, no. 1, pp. 29-41.
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This paper is concerned with some physical layer issues for HIPERLAN. First, the noise performance required of each class of receivers in HIPERLAN is determined. Secondly, the effect of frequency offset on the performance of equalisers is investigated and various techniques for joint equalisation and frequency offset compensation are studied. It is shown that by employing a decision feedback equaliser incorporating a second order phase locked loop, the effect of both the intersymbol interference and frequency offset can be significantly reduced. Using such a technique, the packet error ratio (PER) of a HIPERLAN radio link in a multipath channel is found by simulation.
Guo, Y.J., Vadgama, S. & Tanaka, Y. 2000, 'Advanced base station technologies for UTRAN', Electronics and Communication Engineering Journal, vol. 12, no. 3, pp. 123-132.
To achieve high capacity and to support high-data-rate services in the terrestrial access network (UTRAN) of the third generation Universal Mobile Telecommunications System (UMTS), it is essential to employ some advanced transceiver techniques at the base stations. In this paper, three such techniques are presented: adaptive antennas, multistage parallel interference cancellers and a new hybrid scheme. The operation principles and some simulation results of the techniques are given and some challenging implementation issues are discussed.
Missiroli, M., Guo, Y.J. & Barton, S.K. 2000, 'Near-far resistant channel estimation for CDMA systems using the linear decorrelating detector', IEEE Transactions on Communications, vol. 48, no. 3, pp. 514-524.
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The well-known linear decorrelating detector (LDD) for direct-sequence code-division multiple-access (CDMA) systems provides near-far resistant performance when the timing of each user is accurately known. Traditional CDMA acquisition techniques suffer from high differences in power levels. The estimation accuracy for a user overwhelmed by stronger ones is likely to be unsatisfactory; at the same time, the interference from a user undergoing acquisition or tracking is not removed by the standard LDD. In this paper, a fully near-far resistant technique for acquisition and tracking for asynchronous CDMA systems applying the LDD is proposed, considering realistic band-limited signals. This technique is based on the adoption of a pair of special sequences equivalent to a dedicated access channel and is shown to provide a relatively fast and robust means to perform channel estimation both in case of single- and multipath channels.
Peng, M.K., Sasabo, M.F., Guo, Y.J.J., Downing, O.J. & Barton, S.K. 2000, 'Frame-extended linear decorrelating detector for asynchronous CDMA', IEEE TRANSACTIONS ON VEHICULAR TECHNOLOGY, vol. 49, no. 5, pp. 1918-1927.
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Tellambura, C., Johnson, I.R., Guo, Y.J. & Barton, S.K. 1999, 'Frequency-offset estimation for HIPERLAN', IEEE Transactions on Communications, vol. 47, no. 8, pp. 1137-1139.
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Frequency-offset correction is considered for a HIPERLAN (HIgh-PErformance Radio LAN) system over the indoor radio channel. Since the multipath channel response is not known a priori, a viable frequency-offset estimator should not depend on such knowledge. Such an estimator, using a single sample per symbol, is derived for HIPERLAN. The estimator is shown to approach the Cramer-Rao bound for frequency-offset estimation over a multipath channel. A HIPERLAN system simulation example shows that the performance with an offset of 150 kHz is within 0.5 dB of that of a system with zero frequency offset.
Tellambura, C., Parker, M.G., Guo, Y.J., Shepherd, S.J. & Barton, S.K. 1999, 'Optimal sequences for channel estimation using discrete Fourier transform techniques', IEEE TRANSACTIONS ON COMMUNICATIONS, vol. 47, no. 2, pp. 230-238.
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Tellambura, C., Guo, Y.J. & Barton, S.K. 1998, 'Channel estimation using aperiodic binary sequences', IEEE Communications Letters, vol. 2, no. 5, pp. 140-142.
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Estimating a channel impulse response using a known aperiodic sequence is considered. The problem can be reduced to minimizing the trace of the inverse of a Toeplitz matrix. An efficient algorithm for computing this trace is developed and optimal binary sequences up to length 32 are found and tabulated. The use of complementary sequences in this context is also investigated. It is shown that the eigenvalues of the autocorrelation matrices of a pair of complementary sequences sum to a known constant.
Gillies, D.A.G., Guo, Y.J. & Barton, S.K. 1997, 'Synchronisation Techniques for HIPERLAN', Wireless Personal Communications, vol. 4, no. 1, pp. 1-10.
Timing recovery in the High Performance Radio Local Area Network (HIPERLAN) standard is likely to be performed with the aid of synchronisation sequences embedded in the user data, which will be detected with matched filters. A directed search using a form of genetic algorithm has been performed to obtain suitable sequences of lengths up to 80 bits, and simulations of their performance have been undertaken. Performance of the sequences has been measured under the severe channel conditions that pertain in the indoor environment.
Peng, M., Sasabo, M.F., Guo, Y.J. & Barton, S.K. 1997, 'A modified linear decorrelating detector for asynchronous CDMA', IEE Colloquium (Digest), no. 129.
Although the linear decorrelating detector (LDD) is theoretically a simple scheme for the detection of asynchronous CDMA, its practical implementation is still too complicated and it may have long detection delay. One-shot LDD has a simpler architecture and almost no detection delay, but it could lead to significant noise enhancement, and hence degraded near-far resistance (NFR) than the standard LDD. In this paper, a modified LDD (MLDD) is proposed. With controllable complexity and detection delay, the MLDD has smaller noise enhancement than the one-shot LDD and its NFR can approach that of the standard LDD.
Aikussayer, H.M., Guo, Y.J. & Barton, S.K. 1997, 'New multiuser detector for asynchronous CDMA', IEE Proceedings: Communications, vol. 144, no. 5, pp. 336-340.
A novel multiuser detector for asynchronous code division multiple access (CDMA) system is presented. Using a new type of spreading sequences and shortened correlators with linear combining, an unbiased one-shot suboptimum detection is achieved without increasing the receiver complexity. Two decorrelating algorithms, the direct and the recursive methods, are given for the proposed detector configuration. Theoretical and simulation results show that the receiver performs well in severe near-far environments. &copy; IEE, 1997.
Fu, K., Guo, Y.J. & Barton, S.K. 1997, 'Performance of the EY-NPMA Protocol', Wireless Personal Communications, vol. 4, no. 1, pp. 41-50.
The throughput of the Elimination Yield Non-pre-emptive Priority Multiple Access (EY-NPMA) protocol, which has been chosen as the medium access control (MAC) protocol for HIPERLAN, is simulated. Connection between users is based on a statistical model of path loss with power law against distance and 6 dB log-normal shadowing. It is shown that the throughput performance of the EY-NPMA protocol in networks of moderate size and with small proportion of hidden nodes is satisfactory. For a fully connected network, the throughput reaches 0.85 at an offered traffic of 1 and remains at this level. The maximum throughput reduces gradually when the number of hidden node pairs in the network is increased. With 11% of hidden nodes in the network the peak throughput falls to 0.6.
Guo, Y.J., Paez, A., Sadeghzadeh, R.A. & Barton, S.K. 1997, 'A circular patch antenna for radio LAN's', IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION, vol. 45, no. 1, pp. 177-178.
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Guo, Y.J., Paez, A., Sadeghzadeh, R.A. & Barton, S.K. 1996, 'A patch antenna for HIPERLAN', Wireless Personal Communications, vol. 3, no. 4, pp. 389-396.
A patch antenna suited for indoor HIPERLAN is presented. The antenna operates in T M 02 mode and its radiation pattern is omnidirectional in azimuth and has a null in the normal direction. An experimental prototype has been designed and tested. A 6.1 % bandwidth of VSWR 2 and 4.2 dB antenna gain were measured at 5 GHz band. &copy; 1996 Kluwer Academic Publishers.
Tellambura, C., Guo, Y.J. & Barton, S.K. 1996, 'Co-channel and self-interference analysis for indoor wireless channels', Wireless Personal Communications, vol. 3, no. 4, pp. 411-419.
To achieve a user data rate of 20 Mbit/s in the high performance local area network (HIPERLAN) system operating in indoor environments, channel equalization must be used to mitigate the effects of multipath propagation. If, however, the indoor channel impulse response length is too long, then the multipath power outside of the equalisation capability of the equalizer acts as a form of self interference. Moreover, co-channel interference may also be present at the detector input. Considering these two effects as well as the rms delay spread, this paper derives analytical expressions for the probability of outage. &copy; 1996 Kluwer Academic Publishers.
Tellambura, C., Guo, Y.J. & Barton, S.K. 1996, 'Equaliser performance for HIPERLAN in indoor channels', Wireless Personal Communications, vol. 3, no. 4, pp. 397-410.
In order to accomplish practical deployment modelling for system performance evaluation and comparison for possible modulation and equalisation schemes to be used in HIPERLAN, a wide band tapped delay line (WTDL) channel model has been adopted by ETSI to characterise the multipath fading in the indoor radio environment. Based on this statistical channel model, and using Monte Carlo method, this paper evaluates the average probability of error for linear and decision feedback equalisers as a function of signal-to-noise ratio. It also evaluates the matched filter bound for this channel model. The results show the optimum performance levels achievable via the use of any equaliser. &copy; 1996 Kluwer Academic Publishers.
Guo, Y.J. & Barton, S.K. 1995, 'Phase Correcting Zonal Reflector Incorporating Rings', IEEE Transactions on Antennas and Propagation, vol. 43, no. 4, pp. 350-355.
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An array of Conducting elements printed on a grounded dielectric substrate functions as an electromagnetic phase shifter. With a fixed substrate and a given operating frequency, the phase shift is determined by the array parameters. In the paper, the spectral domain moment method model for analyzing homogeneous reflective phase shifters with conducting rings as elements is presented, and numerical and experimental results are given. A novel phase correcting Fresnel zonal reflector based on this model is reported. A 43% maximum antenna efficiency and -22 dB sidelobe level were measured in X-band. The bandwidth of the reflector is estimated to be greater than 10%. &copy; 1995 IEEE
Guo, Y.J. & Barton, S.K. 1995, 'Analysis of One-Dimensional Zonal Reflectors', IEEE Transactions on Antennas and Propagation, vol. 43, no. 4, pp. 385-389.
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A one-dimensional zonal reflector is a conducting surface which is uniform in one direction and has a zonal profile in the other. Similar to a cylindrical reflector, it converts a cylindrical wave from a line-source into an outgoing plane wave. In this paper, the radiation performance of such reflectors with TM-wave illumination is analyzed by the method of moments (MoM). The influence of corner diffraction and zoning on the sidelobe level is investigated. Three types of configurations are considered, which include the parabolic zonal reflector and two stepwise zonal reflectors of different configurations. It is found that corner diffraction makes a significant contribution to the sidelobe level, but zoning intrinsically raises the far-out sidelobes. Numerical results show that the near-in sidelobes of the stepwise zonal reflector can be significantly decreased by adjusting the geometrical configuration. &copy; 1995 IEEE
GUO, Y.J. & BARTON, S.K. 1995, 'PHASE EFFICIENCY OF THE REFLECTIVE ARRAY ANTENNA', IEE PROCEEDINGS-MICROWAVES ANTENNAS AND PROPAGATION, vol. 142, no. 2, pp. 115-120.
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Guo, Y.J., Sassi, I.H. & Barton, S.K. 1994, 'Multilayer Offset Fresnel Zone Plate Reflector', IEEE Microwave and Guided Wave Letters, vol. 4, no. 6, pp. 196-198.
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An offset phase-correcting Fresnel zone plate (FZP) reflector antenna based on the multilayer configuration is presented. The reflector consists of a conducting ground and four layers of conducting patterns separated by four dielectric substrates. An experimental prototype designed at 10.39 GHz was fabricated and tested. With a 0.32 m by 0.34 m elliptical reflector aperture and a pyramidal feedhorn, the antenna achieved &#8211;20-dB sidelobe level and 61% maximum efficiency. Compared with a phase reversal FZP of the same size, a 3.3-dB gain improvement and significant sidelobe reduction were obtained. &copy; 1994 IEEE
Guo, Y.J., Sassi, I.H. & Barton, S.K. 1994, 'Offset Fresnel lens antenna', IEE Proceedings: Microwaves, Antennas and Propagation, vol. 141, no. 6, pp. 517-522.
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An analysis of the offset Fresnel lens antenna is presented using the vectorial Kirchhoff diffraction theory. Equations for predicting the copolarized and crosspolarized radiation patterns are given. Two approaches to evaluating the far-field integration are introduced. Antenna performance such as the sidelobe and the crosspolarization levels is investigated. An experimental offset Fresnel lens is reported. Measured results agree well with the theoretical prediction.
Guo, Y.J. & Barton, S.K. 1994, 'Offset Fresnel zone plate antennas', International Journal of Satellite Communications, vol. 12, no. 4, pp. 381-385.
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The theory of offset Fresnel zone plate antennas is presented. Explicit formulae for the design of the zone boundaries for the offset Fresnel zone plate are given. Theorectical equations and numerical results for the farfield analysis are presented. It is found that when the offset angle increases, the zone boundaries become more elliptic and the plate becomes more asymmetric in the Eplane. With the number of full wave zones and the plate width in the Wplane fixed, the plate width in the Eplane increases with the offset angle, which keeps the projected aperture area constant. Within a limited range of offset angles, the offset configuration can be employed without degrading the radiation performance much. For large offset angles, however, the asymmetry of the configuration may lead to increased sidelobes and decreased antenna directivity. An experiment with one particular phase reversal zone plate antenna with 30&deg; offset angle shows good agreement between the measured antenna pattern and the theoretical prediction. Copyright &copy; 1994 John Wiley & Sons, Ltd.
Guo, Y.J. & Barton, S.K. 1993, 'Fresnel Zone Plate Reflector Incorporating Rings', IEEE Microwave and Guided Wave Letters, vol. 3, no. 11, pp. 417-419.
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A novel high-efficiency Fresnel zone plate reflector antenna is presented. The reflector consists of an inhomogeneous array of circular conducting rings printed on a grounded substrate. By adjusting the geometrical parameters of the rings and the distances between them, the reflector provides a space-varying phase correction required for focusing an incoming plane wave. Compared with a phase reversal zone plate, an average of 3-dB gain improvement and significant sidelobe reduction have been obtained. &copy; 1993 IEEE
Guo, Y.J. & Barton, S.K. 1993, 'Multilayer phase correcting fresnel zone plate reflector antennas', International Journal of Satellite Communications, vol. 11, no. 2, pp. 75-80.
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Owing to its flat nature and light weight etc., the Fresnel zone plate antenna is becoming very attractive for such applications as DBS reception and receiveonly VSAT. The disadvantages of low efficiency and high sidelobes of the simple and the phase reversing zone plates can be improved by using phase correcting techniques. In this paper, a systematic investigation on the efficiency and sidelobe performance of subzone phase correcting zone plate antennas is presented. The design of a form of multilayer phase correcting zone plate reflector is described. A quarterwave zone plate reflector constructed with three dielectric layers and metallized rings is reported, with measured peak efficiency of 55 per cent. Copyright &copy; 1993 John Wiley & Sons, Ltd.
Guo, Y.J. & Barton, S.K. 1993, 'On the subzone phase correction of fresnel zone plate antennas', Microwave and Optical Technology Letters, vol. 6, no. 15, pp. 840-843.
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Subzone phase correction is a practical technique to produce highefficiency Fresnel zone plate antennas. In this article a strict theory underlying the technique is presented. A closedform expression of the focal field for the subzone phase correcting Fresnel zone plate (FZP) illuminated by a plane wave is given first. The subzone division and the corresponding phase correction are then optimized to produce the maximum focal field intensity. To overcome the difficulty of placing many subzone phase shifters in the narrow outer fullwave zones, an aperiodic subzone phase correction technique is proposed. Copyright &copy; 1993 Wiley Periodicals, Inc., A Wiley Company
Guo, Y.J. & Barton, S.K. 1992, 'A High-Efficiency Quarter-Wave Zone Plate Reflector', IEEE Microwave and Guided Wave Letters, vol. 2, no. 12, pp. 470-471.
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A multilayered quarter-wave zone plate reflector antenna operating in the microwave range is presented. The theory for designing the reflector and experimental results are given. An efficiency of 55% was obtained with a prototype reflector antenna. &copy; 1992 IEEE
Gao, X., Du, J., Zhang, T., Jay Guo, Y. & Foley, C.P., 'Experimental Investigation of a Broadband High-Temperature Superconducting Terahertz Mixer Operating at Temperatures Between 40 and 77 K', Journal of Infrared, Millimeter, and Terahertz Waves.
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