I'm an electrical engineer who has migrated into telecommunications engineering and industrial & medical radiation engineering. I joined UTS in April 2011 after nearly a decade working at the University of Wollongong. I currently teach 42903 MPLS and Services Architecture and 49202 Communication Protocols; I have previously taught 32118 Mobile Application Development and Satellite Communication Systems. My main research activities are now focused on instrumentation, analog and digital signal processing, image processing, data acquisition and analysis for radiation applications, medical and industrial imaging, dosimetry, radiotherapy and Monte Carlo simulation. I am a member of the RF & Communications Technology (RFCT) Lab and the Perceptual Imaging Lab.
My philosophy is that Engineering should be about analysis, design, simulation and then actually building something. The last part is often neglected :-)
- Honourary member, Centre for Medical Radiation Physics, UoW
Can supervise: YES
Some current research activities and collaborations that I am currently involved with include:
- Advanced positron emission tomography (PET) systems (ultra-high resolution, ultra-high sensitivity/low idose);
- Industrial CT imaging;
- Monte Carlo simulation and modelling particle therapy and brachytherapy;
- MAC-layer enhancements to 802.11 for cooperative communication;
- Coverage hole repair strategies for networks of independently mobile nodes;
- Vehicular network channel models, clustering algorithms and routing protocols;
- Communications protocols
- MPLS and Services Architecture
- Mobile application development (Android)
- Satellite communication systems
Ahmed, AM, Chacon, A, Rutherford, H, Akamatsu, G, Mohammadi, A, Nishikido, F, Tashima, H, Yoshida, E, Yamaya, T, Franklin, DR, Rosenfeld, AB, Guatelli, S & Safavi-Naeini, M 2020, 'A validated Geant4 model of a whole-body PET scanner with four-layer DOI detectors', Physics in Medicine & Biology.View/Download from: Publisher's site
Chacon, A, James, B, Tran, L, Guatelli, S, Chartier, L, Prokopvich, D, Franklin, DR, Mohammadi, A, Nishikido, F, Iwao, Y, Akamatsu, G, Takyu, S, Tashima, H, Yamaya, T, Parodi, K, Rosenfeld, A & Safavi-Naeini, M 2020, 'Experimental investigation of the characteristics of radioactive beams for heavy ion therapy', MEDICAL PHYSICS.View/Download from: Publisher's site
Le, AT, Tran, LC, Huang, X, Ritz, C, Dutkiewicz, E, Phung, SL, Bouzerdoum, A & Franklin, D 2020, 'Unbalanced Hybrid AOA/RSSI Localization for Simplified Wireless Sensor Networks', Sensors, vol. 20, no. 14, pp. 3838-3838.View/Download from: Publisher's site
Source positioning using hybrid angle-of-arrival (AOA) estimation and received signal strength indicator (RSSI) is attractive because no synchronization is required among unknown nodes and anchors. Conventionally, hybrid AOA/RSSI localization combines the same number of these measurements to estimate the agents' locations. However, since AOA estimation requires anchors to be equipped with large antenna arrays and complicated signal processing, this conventional combination makes the wireless sensor network (WSN) complicated. This paper proposes an unbalanced integration of the two measurements, called 1AOA/nRSSI, to simplify the WSN. Instead of using many anchors with large antenna arrays, the proposed method only requires one master anchor to provide one AOA estimation, while other anchors are simple single-antenna transceivers. By simply transforming the 1AOA/1RSSI information into two corresponding virtual anchors, the problem of integrating one AOA and N RSSI measurements is solved using the least square and subspace methods. The solutions are then evaluated to characterize the impact of angular and distance measurement errors. Simulation results show that the proposed network achieves the same level of precision as in a fully hybrid nAOA/nRSSI network with a slightly higher number of simple anchors.
Rutherford, H, Chacon, A, Mohammadi, A, Takyu, S, Tashima, H, Yoshida, E, Nishikido, F, Hofmann, T, Pinto, M, Franklin, DR, Yamaya, T, Parodi, K, Rosenfeld, AB, Guatelli, S & Safavi-Naeini, M 2020, 'Dose quantification in carbon ion therapy using in-beam positron emission tomography', Physics in Medicine & Biology.View/Download from: Publisher's site
Wilson, KJ, Alabd, R, Abolhasan, M, Safavi-Naeini, M & Franklin, DR 2020, 'Optimisation of monolithic nanocomposite and transparent ceramic scintillation detectors for positron emission tomography', SCIENTIFIC REPORTS, vol. 10, no. 1.View/Download from: Publisher's site
Chacon, A, Guatelli, S, Rutherford, H, Bolst, D, Mohammadi, A, Ahmed, A, Nitta, M, Nishikido, F, Iwao, Y, Tashima, H, Yoshida, E, Akamatsu, G, Takyu, S, Kitagawa, A, Hofmann, T, Pinto, M, Franklin, DR, Parodi, K, Yamaya, T, Rosenfeld, A & Safavi-Naeini, M 2019, 'Comparative study of alternative Geant4 hadronic ion inelastic physics models for prediction of positron-emitting radionuclide production in carbon and oxygen ion therapy', PHYSICS IN MEDICINE AND BIOLOGY, vol. 64, no. 15.View/Download from: Publisher's site
Chacon, A, Safavi-Naeini, M, Bolst, D, Guatelli, S, Franklin, D, Iwao, Y, Akamatsu, G, Tashima, H, Yoshida, E, Nishikido, F, Kitagawa, A, Mohammadi, A, Gregoire, M-C, Yamaya, T & Rosenfeld, A 2019, 'Monte Carlo investigation of the characteristics of radioactive beams for heavy ion therapy', Scientific Reports, vol. 9, no. 1.View/Download from: Publisher's site
This work presents a simulation study evaluating relative biological effectiveness at 10% survival fraction (RBE10) of several different positron-emitting radionuclides in heavy ion treatment systems, and comparing these to the RBE10s of their non-radioactive counterparts. RBE10 is evaluated as a function of depth for three positron-emitting radioactive ion beams (10C, 11C and 15O) and two stable ion beams (12C and 16O) using the modified microdosimetric kinetic model (MKM) in a heterogeneous skull phantom subject to a rectangular 50 mm × 50 mm × 60 mm spread out Bragg peak. We demonstrate that the RBE10 of the positron-emitting radioactive beams is almost identical to the corresponding stable isotopes. The potential improvement in PET quality assurance image quality which is obtained when using radioactive beams is evaluated by comparing the signal to background ratios of positron annihilations at different intra- and post-irradiation time points. Finally, the incidental dose to the patient resulting from the use of radioactive beams is also quantified and shown to be negligible.
Alabd, R, Safavi-Naeini, M, Wilson, KJ, Rosenfeld, AB & Franklin, DR 2018, 'A simulation study of BrachyShade, a shadow-based internal source tracking system for HDR prostate brachytherapy.', Physics in medicine and biology, vol. 63, no. 20, pp. 205019-205019.View/Download from: Publisher's site
This paper presents a simulation study of BrachyShade, a proposed internal source-tracking system for real time quality assurance in high dose rate prostate brachytherapy. BrachyShade consists of a set of spherical tungsten occluders located above a pixellated silicon photodetector. The source location is estimated by minimising the mean squared error between a parametric model of the shadow image and acquired images of the shadows projected on the detector plane. A novel algorithm is finally employed to correct the systemic error resulting from Compton scattering in the medium. The worst-case error obtained with BrachyShade for a 13.5 ms image acquisition is less than 1.3 mm in the most distant part of the treatment volume, while for 75% of source locations an error of less than 0.42 mm was achieved.
Ghabrial, A, Franklin, D & Zaidi, H 2018, 'A Monte Carlo simulation study of the impact of novel scintillation crystals on performance characteristics of PET scanners.', Physica medica : PM : an international journal devoted to the applications of physics to medicine and biology : official journal of the Italian Association of Biomedical Physics (AIFB), vol. 50, pp. 37-45.View/Download from: Publisher's site
The purpose of this study is to validate a Monte Carlo simulation model for the clinical Siemens Biograph mCT PET scanner using the GATE simulation toolkit, and to evaluate the performance of six different scintillation materials in this model using the National Electrical Manufactures Association (NEMA) NU 2-2007 protocol.A model of the Biograph mCT PET detection system and its geometry was developed. NEMA NU 2-2007 phantoms were also modelled. The accuracy of the developed scanner model was validated through a comparison of the simulation results from GATE, SimSET and PeneloPET toolkits, and experimental data obtained using the NEMA NU 2-2007 protocols. The evaluated performance metrics included count rate performance, spatial resolution, sensitivity, and scatter fraction (SF). Thereafter, the mCT PET scanner was simulated with six different candidate high-performance scintillation materials, including LSO, LaBr3, CeBr3, LuAP, GLuGAG and LFS-3, and its performance evaluated according to the NEMA NU 2-2007 specifications.The Monte Carlo simulation model demonstrates good agreement with the experimental data and results from other simulation packages. For instance, the scatter fraction calculated using GATE simulation is 34.35% while the experimentally measured value is 33.2%, 38.48% for the SimSET, and 34.8% for the PeneloPET toolkit. The best-performing scintillation materials were found to be LuAP, LSO and LFS-3, while GLuGAG offers acceptable performance if cost is the dominant concern.The main performance characteristics of the Biograph mCT PET scanner can be simulated accurately using GATE with a good agreement with other Monte Carlo simulation packages and experimental measurements. Newly developed scintillators show promise and offer alternative options for the design of novel generation PET scanners.
Ismaiel, B, Abolhasan, M, Ni, W, Smith, D, Franklin, D & Jamalipour, A 2018, 'Analysis of effective capacity and throughput of polling-based device-to-device networks', IEEE Transactions on Vehicular Technology, vol. 67, no. 9, pp. 8656-8666.View/Download from: Publisher's site
© 1967-2012 IEEE. Next-generation wireless networks will give rise to heterogeneous networks by integrating multiple wireless access technologies to provide seamless mobility to mobile users with high-speed wireless connectivity. Device-to-device (D2D) communication has proven to be a promising technology that can increase the capacity and coverage of wireless networks. The D2D communication was first introduced in long-term evolution advanced (LTE-A) and has gained immense popularity for the offloading traffic using the licensed and unlicensed band. Challenges arise from resource allocation, provision of quality-of-service (QoS), and the quantification of capacity in an unlicensed band due to the distributed nature of Wi-Fi. In this paper, we propose an analytical performance model for the scalable MAC protocol (SC-MP) in which a resource allocation mechanism is based on the IEEE 802.11 point coordinated function to access the Wi-Fi channel for voice and video/multimedia traffic. In the SC-MP, D2D communication is applied to further offload the video/multimedia traffic. In particular, this paper establishes a three-state semi-Markovian model to derive a closed-form expression of effective capacity in terms of transmission rate and quality-of-service. Further, the SC-MP is analytically modeled using the four-state traditional Markov model to derive the saturation throughput. The analytical results are validated through simulations, hence, proving the appropriateness of the model.
Ismaiel, B, Abolhasan, M, Ni, W, Smith, D, Franklin, D, Dutkiewicz, E, Krunz, MM & Jamalipour, A 2018, 'PCF-based LTE Wi-Fi aggregation for coordinating and offloading the cellular traffic to D2D network', IEEE Transactions on Vehicular Technology, vol. 67, no. 12, pp. 12193-12203.View/Download from: Publisher's site
© 2018 IEEE. Device-to-device (D2D) communication is a promising technology towards 5G networks. D2D communication can offload traffic using licensed/unlicensed band by establishing a direct communication between two users without traversing the base station or core network. However, one of the major challenges of D2D communication is resource allocation and guaranteeing quality-of-service (QoS). In this paper, we establish an optimal queuing scheduling and resource allocation problem for three-tier heterogeneous network based on LTE Wi-Fi aggregation, to offload voice/multimedia traffic from licensed band to unlicensed band using scalable MAC protocol (SC-MP) under various static delay constraints. The access mechanism used for Wi-Fi in SC-MP is point coordination function, which further offloads the multimedia traffic using D2D communication in unlicensed band. Resource allocation and optimal joint queuing scheduling problems are formulated with diverse QoS guarantee between licensed and unlicensed band to minimize the bandwidth of licensed band. Furthermore, an iterative algorithm is proposed to express the nonconvex problem as a series of subproblems based on block coordinate descent and difference of two convex functions (D.C) program. We have simulated the proposed scheme using two scenarios: Voice traffic using licensed band and voice traffic using both licensed and unlicensed band, whereas multimedia traffic uses unlicensed band for both the scenarios. The simulation results show that both the schemes perform better than the existing scheme and scenario 2 outperforms scenario 1.
Safavi-Naeini, M, Chacon, A, Guatelli, S, Franklin, DR, Bambery, K, Gregoire, M-C & Rosenfeld, A 2018, 'Opportunistic dose amplification for proton and carbon ion therapy via capture of internally generated thermal neutrons.', Scientific reports, vol. 8, no. 1.View/Download from: Publisher's site
This paper presents Neutron Capture Enhanced Particle Therapy (NCEPT), a method for enhancing the radiation dose delivered to a tumour relative to surrounding healthy tissues during proton and carbon ion therapy by capturing thermal neutrons produced inside the treatment volume during irradiation. NCEPT utilises extant and in-development boron-10 and gadolinium-157-based drugs from the related field of neutron capture therapy. Using Monte Carlo simulations, we demonstrate that a typical proton or carbon ion therapy treatment plan generates an approximately uniform thermal neutron field within the target volume, centred around the beam path. The tissue concentrations of neutron capture agents required to obtain an arbitrary 10% increase in biological effective dose are estimated for realistic treatment plans, and compared to concentrations previously reported in the literature. We conclude that the proposed method is theoretically feasible, and can provide a worthwhile improvement in the dose delivered to the tumour relative to healthy tissue with readily achievable concentrations of neutron capture enhancement drugs.
Cooper, C, Franklin, D, Ros, M, Safaei, F & Abolhasan, M 2017, 'A Comparative Survey of VANET Clustering Techniques', IEEE Communications Surveys Tutorials, vol. 19, no. 1, pp. 657-681.View/Download from: Publisher's site
A vehicular ad hoc network (VANET) is a mobile ad hoc network (MANET) in which network nodes are vehicles – most commonly road vehicles. VANETs present a unique range of challenges and opportunities for routing protocols due to the semi-organised nature of vehicular movements subject to the constraints of road geometry and rules, and the obstacles which limit physical connectivity in urban environments. In particular, the problems of routing protocol reliability and scalability across large urban VANETs are currently the subject of intense research. Clustering can be used to improve routing scalability and reliability in VANETs, as it results in the distributed formation of hierarchical network structures by grouping vehicles together based on correlated spatial distribution and relative velocity. In addition to the benefits to routing, these groups can serve as the foundation for accident or congestion detection, inforomation dissemination and entertainment applications. This paper explores the design choices made in the development of clustering algorithms targeted at VANETs. It presents a taxonomy of the techniques applied to solve the problems of cluster head election, cluster affiliation and cluster management, and identifies new directions and recent trends in the design of these algorithms. Additionally, methodologies for validating clustering performance are reviewed, and a key shortcoming – the lack of realistic vehicular channel modelling – is identified. The importance of a rigorous and standardised performance evaluation regime utilising realistic vehicular channel models is demonstrated.
Pourashraf, P, Safaei, F & Franklin, DR 2017, 'A Study of User Perception of the Quality of Video Content Rendered Inside a 3D Virtual Environment', IEEE Journal of Selected Topics in Signal Processing, vol. 11, no. 1, pp. 125-125.View/Download from: Publisher's site
This paper reports on the result of a user study to assess the impact of resolution and frame rate of video on the Quality of Experience of the users, when the video is rendered inside a 3D virtual space, and consequently viewed from arbitrary perspectives. A mathematical model for video rate is presented that expresses the total rate as the product of separate functions of spatial and temporal resolutions. Results from the user study are combined with the model to predict the rate parameters which will result in perceptually acceptable quality using the 3D features of the virtual environment. The results show that by exploiting the insensitivity of users to controlled quality degradation, the downstream network load for the client can be significantly reduced with little or no perceptual impact on the clients.
Alnaghy, S, Safavi-Naeini, M, Franklin, DR, Han, Z, Cutajar, DL, Petasecca, M, Lerch, M & Rosenfeld, AB 2016, 'Analytical Modelling and Simulation of Single and Double Cone Pinholes for Real-Time In-Body Tracking of an HDR Brachytherapy Source', IEEE TRANSACTIONS ON NUCLEAR SCIENCE, vol. 63, no. 3, pp. 1375-1385.View/Download from: Publisher's site
Hagelstein, B, Abolhasan, M, Franklin, D, Ni, W & Safaei, F 2016, 'Analytic Performance Model for State-Based MAC Layer Cooperative Retransmission Protocols', IEEE Transactions on Mobile Computing, vol. 15, no. 1, pp. 32-44.View/Download from: Publisher's site
COOPERATIVE retransmission is a well-established technique
for improving wireless network capacity . Its
effectiveness is strongly dependent on the choice of relay
selection algorithm, as this determines both the probability
of retransmission success and the probability of collisions
between simultaneous retransmission attempts. Consequently,
relay selection algorithm design remains an open
area of research.
Odeh, N, Abolhasan, M, Safaei, F, Franklin, DR & Mao, G 2016, 'Utility-based resource allocation for interference limited OFDMA cooperative relay networks', PHYSICAL COMMUNICATION, vol. 20, pp. 74-84.View/Download from: Publisher's site
Cooper, C, Mukunthan, A, Ros, M, Safaei, F, Abolhasan, M & Franklin, DR 2015, 'Including general environmental effects in K-factor approximation for Rice-distributed VANET channels', Physical Communication, vol. 14, pp. 32-44.View/Download from: Publisher's site
This paper presents a method of approximating the Rician K-factor based on the instantaneous static environment. The strongest signal propagation paths are resolved in order to determine specular and diffuse powers for approximation. The model is experimentally validated in two different urban areas in New South Wales, Australia. Good agreement between the model and experimental data was obtained over short-range communication links, demonstrating the suitability of the model in urban VANETs. The paper concludes with recommendations for methods to account for vehicles in the simulation and incorporating additional phenomena (such as scattering) in the approximation.
Li, K, Safavi-Naeini, M, Franklin, DR, Han, Z, Rosenfeld, AB, Hutton, B & Lerch, MLF 2015, 'A new virtual ring-based system matrix generator for iterative image reconstruction in high resolution small volume PET systems', PHYSICS IN MEDICINE AND BIOLOGY, vol. 60, no. 17, pp. 6949-6973.View/Download from: Publisher's site
Safavi-Naeini, M, Han, Z, Alnaghy, S, Cutajar, D, Petasecca, M, Lerch, MLF, Franklin, DR, Bucci, J, Carrara, M, Zaider, M & Rosenfeld, AB 2015, 'BrachyView, a novel in-body imaging system for HDR prostate brachytherapy: Experimental evaluation', Medical Physics, vol. 42, no. 12, pp. 7098-7107.View/Download from: Publisher's site
This paper presents initial experimental results from a prototype of high dose rate (HDR) BrachyView, a novel in-body source tracking system for HDR brachytherapy based on a multipinhole tungsten collimator and a high resolution pixellated silicon detector array. The probe and its associated position estimation algorithms are validated and a comprehensive evaluation of the accuracy of its position estimation capabilities is presented.
The HDR brachytherapy source is moved through a sequence of positions in a prostate phantom, for various displacements in x, y, and z. For each position, multiple image acquisitions are performed, and source positions are reconstructed. Error estimates in each dimension are calculated at each source position and combined to calculate overall positioning errors. Gafchromic film is used to validate the accuracy of source placement within the phantom.
More than 90% of evaluated source positions were estimated with an error of less than one millimeter, with the worst-case error being 1.3 mm. Experimental results were in close agreement with previously published Monte Carlo simulation results.
The prototype of HDR BrachyView demonstrates a satisfactory level of accuracy in its source position estimation, and additional improvements are achievable with further refinement of HDR BrachyView's image processing algorithms.
Han, Z, Safavi-Naeini, M, Alnaghy, S, Cutajar, DL, Guatelli, S, Petasecca, M, Franklin, DR, Malaroda, A, Carrara, M, Bucci, J, Zaider, M, Lerch, MLF & Rosenfeld, AB 2014, 'Radiation dose enhancement at tissue-tungsten interfaces in HDR brachytherapy', PHYSICS IN MEDICINE AND BIOLOGY, vol. 59, no. 21, pp. 6659-6671.View/Download from: Publisher's site
Safaei, F, Pourashraf, P & Franklin, DR 2014, 'Large-scale immersive video conferencing by altering video quality and distribution based on the virtual context', IEEE Communications Magazine, vol. 52, no. 8, pp. 66-72.View/Download from: Publisher's site
Current video conferencing applications do not scale to support a large number of participants. This article describes an IVC system that combines the best attributes of video conferencing and multi-user virtual environments. It is shown that each participant of IVC has a virtual context that is defined by his/her perspective and perception about the quality and relevance of video and audio of others. The virtual context determines both the visibility status and the required quality of videos of participants. This information can be used to dynamically alter the multicast trees that are formed among clients for the purpose of multimedia dissemination so that only the relevant videos are transmitted to end users. In addition, it is possible to reduce the video quality of a given user in response to the virtual context without the degradation having any perceptual impact. The combination of these factors reduces the required upload and download bandwidth of clients by more than 90 percent on average, making IVC highly scalable to support very large gatherings.
AlAamri, H, Abolhasan, M, Franklin, DR & Lipman, J 2013, 'Optimised relay selection for route discovery in reactive routing', Ad Hoc Networks, vol. 11, no. 1, pp. 70-88.View/Download from: Publisher's site
On-demand routing protocols have the potential to provide scalable information delivery in large ad hoc networks. The novelty of these protocols is in their approach to route discovery, where a route is determined only when it is required by initiating a route discovery procedure. Much of the research in this area has focused on reducing the route discovery overhead when prior knowledge of the destination is available at the source or by routing through stable links. Hence, many of the protocols proposed to date still resort to flooding the network when prior knowledge about the destination is un-available. This paper proposes a novel routing protocol for ad hoc networks, called On-demand Tree-based Routing Protocol (OTRP). This protocol combines the idea of hop-by-hop routing (as used by AODV) with an efficient route discovery algorithm called Tree-based Optimised Flooding (TOF) to improve scalability of ad hoc networks when there is no prior knowledge about the destination. To achieve this in OTRP, route discovery overheads are minimised by selectively flooding the network through a limited set of nodes, referred to as branching nodes. The key factors governing the performance of OTRP are theoretically analysed and evaluated, including the number of branch nodes, location of branching nodes and number of Route REQuest (RREQ) retries. It was found that the performance of OTRP (evaluated using a variety of well-known metrics) improves as the number of branching nodes increases and the number of consumed RREQ retries is reduced. Additionally, theoretical analysis and simulation results shows that OTRP outperforms AODV. DYMO, and OLSR with reduced overheads as the number of nodes and traffic load increases.
Hagelstein, B, Abolhasan, M, Franklin, DR & Safaei, F 2013, 'Improving Fairness in IEEE 802.11 Networks Using MAC Layer Opportunistic Retransmission', Computer Networks, vol. 57, no. 17, pp. 3410-3427.View/Download from: Publisher's site
This paper introduces DAFMAC (Decode And Forward MAC), a scalable opportunistic cooperative retransmission enhancement for the IEEE 802.11 MAC protocol which operates without the need for additional explicit control signalling. Distributed opportunistic retransmission algorithms rely on selecting a single suitable relay without direct arbitration between nodes. Simulations show that DAFMAC offers a significant improvement in fairness for both throughput and jitter, giving multiple parallel data flows a more equal opportunity to utilise the channel. DAFMAC cooperative retransmissions are shown to reduce node energy consumption for a given throughput. Further, the DAFMAC relay selection algorithm is shown to scale very well in terms of complexity and memory requirements in comparison to other cooperative retransmission schemes.
Li, K, Safavi-Naeini, M, Franklin, DR, Petasecca, M, Guatelli, S, Rosenfeld, A, Hutton, B & Lerch, M 2013, 'A feasibility study of PETiPIX: an ultra high resolution small animal PET scanner', Journal of Instrumentation, vol. 8, no. 12, pp. 1-15.View/Download from: Publisher's site
PETiPIX is an ultra high spatial resolution positron emission tomography (PET) scanner designed for imaging mice brains. Four Timepix pixellated silicon detector modules are placed in an edge-on configuration to form a scanner with a field of view (FoV) 15 mm in diameter. Each detector module consists of 256 × 256 pixels with dimensions of 55 × 55 × 300 µm3. Monte Carlo simulations using GEANT4 Application for Tomographic Emission (GATE) were performed to evaluate the feasibility of the PETiPIX design, including estimation of system sensitivity, angular dependence, spatial resolution (point source, hot and cold phantom studies) and evaluation of potential detector shield designs. Initial experimental work also established that scattered photons and recoil electrons could be detected using a single edge-on Timepix detector with a positron source. Simulation results estimate a spatial resolution of 0.26 mm full width at half maximum (FWHM) at the centre of FoV and 0.29 mm FWHM overall spatial resolution with sensitivity of 0.01%, and indicate that a 1.5 mm thick tungsten shield parallel to the detectors will absorb the majority of non-coplanar annihilation photons, significantly reducing the rates of randoms. Results from the simulated phantom studies demonstrate that PETiPIX is a promising design for studies demanding high resolution images of mice brains.
Masihpour, M, Abolhasan, M & Franklin, DR 2013, 'Multihop Relay Techniques for Communication Range Extension in Near-Field Magnetic Induction Communication Systems', Journal of Networks, vol. 8, no. 5, pp. 999-1011.View/Download from: Publisher's site
In this paper, multihop relaying in RF-based communications and near field magnetic induction communication (NFMIC) is discussed. Three multihop relay strategies for NFMIC are proposed: Non Line of Sight Magnetic Induction Relay (NLoS-MI Relay), Non Line of Sight Master/Assistant Magnetic Induction Relay1 (NLoS-MAMI Relay1) and Non Line of Sight Master/Assistant Magnetic Induction Relay2 (NLoSMAMI Relay2). In the first approach only one node contributes to the communication, while in the other two techniques (which are based on a master-assistant strategy), two relaying nodes are employed. This paper shows that these three techniques can be used to overcome the problem of dead spots within a body area network and extend the communication range without increasing the transmission power and the antenna size or decreasing receiver sensitivity. The impact of the separation distance between the nodes on the achievable RSS and channel data rate is evaluated for the three techniques. It is demonstrated that the technique which is most effective depends on the specific network topology. Optimum selection of nodes as relay master and assistant based on the location of the nodes is discussed. The paper also studies the impact of the quality factor on achievable data rate. It is shown that to obtain the highest data rate, the optimum quality factor needs to be determined for each proposed cooperative communication method.
Safavi-Naeini, M, Han, Z, Cutajar, D, Guatelli, S, Petasecca, M, Lerch, MLF, Franklin, DR, Jakubek, J, Pospisil, S, Bucci, J, Zaider, M & Rosenfeld, AB 2013, 'BrachyView, A novel inbody imaging system for HDR prostate brachytherapy: Design and Monte Carlo feasibility study', MEDICAL PHYSICS, vol. 40, no. 7.View/Download from: Publisher's site
To achieve higher data rate or to extend the coverage range of a wireless communication system, cooperative relay has been seen as a promising solution. This concept has been integrated in many traditional wireless communication networks. However, it has not been extensively examined for near field magnetic induction communication (NFMIC) systems. This paper aims to apply cooperative relay to NFMIC in a sense that is applicable to body area networking, since NFMIC is stated to be a suitable physical layer for body area networks. We have shown that using idle NFMIC nodes as relaying terminals, the system performance will be enhanced, as compared to a point to point communication system. In this context we have proposed three relaying methods to enhance the data rate and the received signal power in a personal area network. The relaying strategies are denoted as MI-Relay, MAMI Relay1 and MAMI Relay2. In this paper, using theoretical studies and simulation results, we have compared the performance of the three strategies and we have shown that higher data rates can be achieved through MAMI Relay1. However, we have discussed that the separation distance between relaying nodes and the source or destination can be a key factor for relay node selection.
Barua, B, Abolhasan, M, Safaei, F & Franklin, DR 2011, 'On the Error Exponent of Amplify and Forward Relay Networks', IEEE Communications Letters, vol. 15, no. 10, pp. 1047-1049.View/Download from: Publisher's site
In this letter we derive the exact random coding error exponent of a dual hop amplify and forward (AF) relay network with channel state information (CSI) assisted ideal relay gain. Numerical results have been presented, which provide insight about the performance tradeoff between the error exponent and the data rate of the network. Finally we present the capacity analysis of this relay network.
Weaver, M, Green, J, Petasecca, M, Lerch, MLF, Cutajar, D, Franklin, D, Jakubek, J, Carolan, MG, Conway, M, Pospisil, S, Kron, T, Metcalfe, P, Zaider, M & Rosenfeld, AB 2011, 'Three-dimensional dosimetry imaging of I-125 plaque for eye cancer treatment', NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT, vol. 633, pp. S276-S278.View/Download from: Publisher's site
Safavi-Naeini, M, Franklin, DR, Lerch, M, Petasecca, M, Pignatel, G, Reinhard, M, Dalla Betta, G, Zorzi, N & Rosenfeld, A 2009, 'Evaluation of silicon detectors with integrated JFET for biomedical applications', IEEE Transactions on Nuclear Science, vol. 56, no. 3, pp. 1051-1055.View/Download from: Publisher's site
This paper presents initial results from electrical, spectroscopic and ion beam induced charge (IBIC) characterisation of a novel silicon PIN detector, featuring an on-chip n -channel JFET and matched feedback capacitor integrated on its p-side (frontside). This structure reduces electronic noise by minimising stray capacitance and enables highly efficient optical coupling between the detector back-side and scintillator, providing a fill factor of close to 100%. The detector is specifically designed for use in high resolution gamma cameras, where a pixellated scintillator crystal is directly coupled to an array of silicon photodetectors. The on-chip JFET is matched with the photodiode capacitance and forms the input stage of an external charge sensitive preamplifier (CSA). The integrated monolithic feedback capacitor eliminates the need for an external feedback capacitor in the external electronic readout circuit, improving the system performance by eliminating uncontrolled parasitic capacitances. An optimised noise figure of 152 electrons RMS was obtained with a shaping time of 2 mus and a total detector capacitance of 2 pF. The energy resolution obtained at room temperature (2degC) at 27 keV (direct interaction of I-125 gamma rays) was 5.09%, measured at full width at half maximum (FWHM). The effectiveness of the guard ring in minimising the detector leakage current and its influence on the total charge collection volume is clearly demonstrated by the IBIC images.
Hoang, HS, Phuong Pham, C, Franklin, D, van Walsum, T & Ha Luu, M 2019, 'An Evaluation of CNN-based Liver Segmentation Methods using Multi-types of CT Abdominal Images from Multiple Medical Centers', 2019 19th International Symposium on Communications and Information Technologies (ISCIT), International Symposium on Communications and Information Technologies, IEEE, Ho Chi Minh City, Vietnam.View/Download from: Publisher's site
Automatic segmentation of CT images has recently been applied in several clinical liver applications. Convolutional Neural Networks (CNNs) have shown their effectiveness in medical image segmentation in general and also in liver segmentation. However, liver image quality may vary between medical centers due to differences in the use of CT scanners, protocols, radiation dose, and contrast enhancement. In this paper, we investigate three wells known CNNs, FCN-CRF, DRIU, and V-net, for liver segmentation using data from several medical centers. We perform qualitative evaluation of the CNNs based on Dice score, Hausdorff distance, mean surface distance and false positive rate. The results show that all three CNNs achieved a mean Dice score of over 90% in liver segmentation with typical contrast enhanced CT images of the liver. p-values from paired T-test on Dice score of the three networks using Mayo dataset are larger than 0.05 suggesting that no statistical significant difference in their performance. DRIU performs the best in term of processing time. The results also demonstrate that those CNNs have reduced performance in liver segmentation in the case of low-dose and non-contrast enhanced CT images. In conclusion, these promising results enable further investigation of alternative deep learning based approaches to liver segmentation using CT images.
Wilson, K, Alabd, R, Abolhasan, M, Franklin, D & Safavi-Naeini, M 2019, 'Localisation of the Lines of Response in a Continuous Cylindrical Shell PET Scanner', 2019 41st Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC), IEEE Engineering in Medicine and Biology Conference, IEEE, Berlin, Germany.
This work presents a technique for localising the endpoints of the lines of response in a PET scanner based on a continuous cylindrical shell scintillator. The technique is demonstrated by applying it to a simulation of a sensitivity-optimised continuous cylindrical shell PET system using two novel scintillator materials - a transparent ceramic garnet, GLuGAG:Ce, and a LuF$_3$:Ce-polystyrene nanocomposite. Error distributions for the endpoints of the lines of response in the axial, tangential and radial dimension as well as overall endpoint spatial error are calculated for three source positions; the resultant distribution of error in the placement of the lines of response is also estimated.
Ghabrial, A, Franklin, D & Zaidi, H 2018, 'Characterization of the scatter component in large axial field-of-view PET scanners: A Monte Carlo simulation study', 2018 IEEE Nuclear Science Symposium and Medical Imaging Conference, NSS/MIC 2018 - Proceedings.View/Download from: Publisher's site
© 2018 IEEE. A simulation study was conducted to estimate the scatter fraction (SF) and to determine the most suitable line source radial offset displacement required to measure the SF for the total body long axial field-of-view (LAFOV) PET scanner by simulating different cylindrical and anthropomorphic digital phantoms. Simulations are conducted using a scanner model together with scatter phantoms adapted from the NEMA NU-2 2007 scatter phantom design, modified to suit the dimensions of the respective scanners, with line sources of various activities placed at a 45 mm radial offset. SF estimates obtained using the NEMA protocol are compared to values obtained with uniformly filled water phantom of the same length. A whole-body study is conducted using a set of 12 anthropomorphic phantoms with different BMIs, with different organs and anatomical structures filled with realistic concentrations of 18F-FDG. The SF obtained at 45 mm radial offset using 1 kBq/ml with the 200 cm (LAFOV scanner) and 70 cm (mCT) cylindrical phantoms are 40.07% and 34.35%, respectively. In both cases, a comparison with the SF estimate obtained with a uniformly filled cylindrical phantom shows that the NEMA NU2-2007 phantom with the line source positioned at the recommended radial offset of 45 mm significantly overestimates the SF. Instead, it was found that for both scanners, the optimal radial offset for accurate estimation of the SF was approximately 60 mm. High SF correlation coefficients were obtained between the SFs estimated with anthropomorphic phantoms with realistic biodistribution of 18F-FDG and an equivalent volume cylindrical phantom for the LAFOV PET scanner; in addition, BMI was strongly positively correlated with SF. The SF is found to be higher for the LAFOV compared with the mCT PET scanner. The optimal radial displacement for a LAFOV PET scanner using a NEMA-like phantom was found to be 60 mm, compared to the value of 45 mm suggested by the NEMA protocol.
Rafiei, A, Abolhasan, M, Franklin, DR, Safaei, F, Smith, S & Ni, W 2017, 'Cooperative recovery of coverage holes in WSNs via disjoint spanning trees', 2017, 11th International Conference on Signal Processing and Communication Systems, ICSPCS 2017 - Proceedings, International Conference on Signal Processing and Communication Systems, IEEE, Gold Coast, QLD, Australia, pp. 1-10.View/Download from: Publisher's site
© 2017 IEEE. Large scale coverage holes (CHs) resulting from correlated node failures, can significantly degrade quality of service and also jeopardise the integrity of WSNs. In the absence of centralised control, the distributed relocation of deployed nodes becomes a promising solution especially in harsh and hostile environments. In this paper, a distributed method is proposed that enables a network to partially or entirely repair itself through a collection of distributed movements of disjoint spanned trees (DS-Trees) towards the CHs. DS-Trees are spanned based on the nodes distances from the CHs, which are autonomously perceived by the nodes and their one-hop neighbours. DS-Trees around the CHs are spanned in a downstream style outwards from the holes, as nodes select their parents based on the minimum distance to the CH from their neighbours; nodes then decide whether or not to follow the movements of their DS-Trees parents. To examine the efficiency of the proposed model, its performance is compared with two Voronoi-based and one force-based node relocation algorithms. Results show that the proposed DS-Tree model either outperforms or matches the alternative approaches across a wide range of scenarios.
Ismaiel, B, Abolhasan, M, Smith, D, Ni, W & Franklin, D 2017, 'A Survey and Comparison of Device-to-Device Architecture Using LTE Unlicensed Band', IEEE Vehicular Technology Conference, IEEE Vehicular Technology Conference, IEEE, Sydney, NSW, Australia, pp. 1-5.View/Download from: Publisher's site
© 2017 IEEE. Due to the rapid increase in data traffic, one of the solutions provided by mobile operators is to operate Long Term Evolution (LTE) in the unlicensed 5GHz band, as the licensed spectrum is becoming scarce. Mobile operators can expand their network capacity by operating LTE in the unlicensed band at lower cost when compared with using other licensed bands. Device to Device (D2D) communication, proven to be another effective way to enhance the capacity of a network, enables direct data exchange of localized traffic of users in proximity. Applying D2D communication to LTE unlicensed 5GHz band will further improve the network performance and user experience. In this article, we will discuss the new type of solutions that have been proposed for LTE operating in an unlicensed 5GHz band that includes; LTE-Unlicensed (LTE-U), LTE-License Assisted Access (LTE-LAA), LTE WiFi Link Aggregation (LWA), and MuLTEfire. We will discuss the important features along with their advantages and disadvantages and compare these technologies as well. We simulate LTE-LAA, LWA and MuLTEfire technologies in the presence of Wi-Fi hotspot and compare their results. Furthermore, we apply D2D communication to these technologies and from the results we conclude that MuLTEfire can increase the throughput drastically but network saturates quickly. Whereas, applying D2D communication with LWA is beneficial for a scalable network as it will not only increase the network throughput but will increase the network capacity as well.
Ismaiel, B, Abolhasan, M, Smith, D, Ni, W & Franklin, D 2017, 'Scalable MAC protocol for D2D communication for future 5G networks', 2017 14th IEEE Annual Consumer Communications and Networking Conference, CCNC 2017, 2017 14th IEEE Annual Consumer Communications & Networking Conference, IEEE, Las Vegas, NV, USA, pp. 542-547.View/Download from: Publisher's site
© 2017 IEEE. Device-to-device communication (D2D) will be an integral part of 5G wireless networks. Device-to-Device (D2D) communication provide the additional resources to the cellular users for spatially reusing licensed/unlicensed spectrum by establishing direct communication. Although, D2D communication is gaining significant attention towards offloading traffic in heterogeneous networks in licensed band, no attention has been given to offload traffic in an unlicensed band in a centralized manner. However, a major challenge of D2D communication is managing resources in an efficient manner in a heterogeneous network. This paper will direct a new approach to D2D Communication and will present a scalable MAC protocol for D2D communications based on Point Coordination Function (PCF) access mechanism. The importance of PCF access mechanism is that it operates in a centralized manner and highly suitable for the dense environment, hence, can create a centralized control in a distributive manner. In this article, we propose an innovative three tier 5G architecture for D2D communication, which will offload cellular traffic from the cellular network to the WLAN in a dense environment. Moreover, we will present a new centralized scalable MAC protocol for D2D communication between WLAN users, based on the IEEE 802.11 Point Coordination Function (PCF) access mechanism. Our simulation results show that the proposed MAC scheme can increase the capacity of the network and perform better relative to the legacy Distributed coordination Function (DCF) defined in IEEE 802.11.
Mukunthan, A, Cooper, C, Safaei, F, Franklin, D & Abolhasan, M 2017, 'Leveraging the Propagation Model to Make Greedy Routing Decisions in Urban Environments', Proceedings of the 85th IEEE Vehicular Technology Conference, IEEE Vehicular Technology Conference, IEEE, Sydney, NSW, Australia, pp. 1-6.View/Download from: Publisher's site
© 2017 IEEE. The CORNER propagation model, first proposed in 2010, has been previously validated and found to be a reasonably accurate representation of propagation scenarios in urban Vehicular Ad Hoc Networks (VANETs). This paper considers the impact of the propagation environment on routing performance and reveals a pressing need to consider more accurate propagation models when designing urban VANET routing protocols. A greedy routing protocol, which uses CORNER's propagation estimates for neighbour selection, is then presented. The new protocol, named Corner Propagation Stateless Routing (CPSR) is compared to GPSR, a benchmark protocol for VANETs, showing between 87% and 300% improvement in packet delivery ratio at higher network loads.
Rafiei, A, Abolhasan, M, Franklin, DR, Safaei, F, Smith, S & Ni, W 2017, 'Effect of the number of participating nodes on recovery of WSN coverage holes', 2017 27th International Telecommunication Networks and Applications Conference, ITNAC 2017, International Telecommunication Networks and Applications Conference, IEEE, Melbourne, VIC, Australia, pp. 1-8.View/Download from: Publisher's site
© 2017 IEEE. Coverage holes (CHs) due to the correlated node failures, if not appropriately addressed in a timely manner, not only disrupt network's operation but also can compromise its integrity. In the absence of centralised control, distributed node relocation can be an effective solution to recover CHs. Relocation algorithms that mainly applied to all nodes to address networks' coverage and unbalanced deployments problems, are not efficient as participating nodes beyond a certain distance and depth from the CHs do not significantly contribute to recovery of CHs. Here, the effects of the number of participating nodes and movement iterations on recovery of CHs are examined in two Voronoi-based and one force-based node relocation algorithms.
Rafiei, A, Abolhasan, M, Maali, Y & Franklin, D 2015, 'A Geometrical Sink-Based Cooperative Coverage Hole Recovery Strategy for WSNs', Proceedings of the 9th International Conference on Signal Processing and Communication Systems, International Conference on Signal Processing and Communication Systems, IEEE, Cairns, Australia, pp. 1-8.View/Download from: Publisher's site
Unlike sporadic node failures, coverage holes emerging from multiple temporally-correlated node failures can severely affect quality of service in a network and put the integrity of entire wireless sensor networks at risk. Conventional topology control schemes addressing such undesirable topological changes have usually overlooked the status of participating nodes in the recovery process with respect to the deployed sink node(s) in the network. In this paper, a cooperative coverage hole recovery model is proposed which utilises the simple geometrical procedure of circle inversion. In this model, autonomous nodes consider their distances to the deployed sink node(s) in addition to their local status, while relocating towards the coverage holes. By defining suitable metrics, the performance of our proposed model performance is compared with a force-based approach.
Cooper, C, Mukunthan, A, Ros, M, Franklin, DR & Abolhasan, M 2014, 'Dynamic Environmental Fading in Urban VANETs', Communications (ICC), 2014 IEEE International Conference on, IEEE International Conference on Communications, IEEE, Sydney, NSW, Australia, pp. 5641-5646.View/Download from: Publisher's site
A method of approximating the Rician K-Factor with considerations of the local human-built environment is proposed for urban VANETs. The model is validated experimentally on a busy street in Australia, in the presence and absence of other vehicles. The model is found to accurately predict actual channel measurements in close-range communications scenarios.
Cooper, C, Ros, M, Safaei, F, Abolhasan, M & Franklin, D 2014, 'Simulation of Contrasting Clustering Paradigms under an Experimentally-derived Channel Model', Vehicular Technology Conference (VTC Fall), 2014 IEEE 80th, IEEE Vehicular Technology Conference, IEEE, Vancouver, BC, pp. 1-6.View/Download from: Publisher's site
This is a simulation study of weight-based and precedence-based clustering paradigms in VANETs under an experimentally-derived channel model. The study reveals that CH election schemes accounting for driver intention form more stable and long-lived clusters. The results also show that ignoring elements of the VANET channel (such as vehicular shadowing) results in an unreliable comparative analysis of protocol performance.
Pourashraf, P, Safaei, F & Franklin, DR 2014, 'Minimisation of video downstream bit rate for large scale immersive video conferencing by utilising the perceptual variations of quality', Multimedia and Expo (ICME), 2014 IEEE International Conference on, IEEE International Conference on Multimedia and Expo, IEEE, Chengdu, China, pp. 1-6.View/Download from: Publisher's site
Rafiei, A, Maali, Y, Abolhasan, M, Franklin, D & Smith, S 2013, 'An iteratively tuned fuzzy logic movement model in WSN using particle swarm optimization', 2013, 7th International Conference on Signal Processing and Communication Systems, ICSPCS 2013 - Proceedings, International Conference on Signal Processing and Communication Systems, IEEE, Carrara, VIC, Australia.View/Download from: Publisher's site
In contrast to adding new nodes, relocation of deployed nodes in mobile wireless sensor networks seems to be an effective solution to cope with undesirable, unpredictable and uncontrolled network topology changes due to nodes' drift and failure. At the price of less global control, there is a trend in recent years towards giving nodes more autonomy and devising localized relocation algorithms to address challenges of network topology control in harsh and hostile environments in the absence of centralized control. Inspired by laws of nature, a large variety of distributed node relocation algorithms have been designed to alleviate undesirable oscillations caused by local interactions and uncertainties among autonomous nodes as they reach their desired formations. Force-based distributed relocation algorithms governed by virtual push-pull forces among autonomous nodes are among such aforesaid algorithms. Adapting fuzzy logic model in exerting proper amount of forces to reduce node movement oscillation seems to be promising as its conforms well with uncertainties and interactions of autonomous nodes. However, parameters of fuzzy logic relocation model should be tuned so to enable nodes to exert proper amount of forces among their in-range neighbours. In this paper, by using particle swarm optimization, parameters of fuzzy relocation model are obtained based on the desired combinations of performance metrics within nodes' range in each movement iteration. The result shows that our model either outperforms or matches DSSA movement model. © 2013 IEEE.
Zhang, S & Franklin, DR 2014, 'Feasibility study on the implementation of IEEE 802.11 on cloud-based radio over fibre architecture', Communications (ICC), 2014 IEEE International Conference on, IEEE International Conference on Communications, IEEE, Sydney, pp. 2891-2896.View/Download from: Publisher's site
This paper investigates the throughput performance of the IEEE 802.11 MAC when the physical layer is implemented remotely on a cloud-based SDR platform. An analytical model which considers a non-zero late ACK arrival probability is proposed to analyse throughput performance. Both conventional DCF and the Block ACK enhancement from current IEEE 802.11 standards are analysed using the proposed model. Results show that the network delay variance significantly degrades the performance of conventional DCF while enabling Block ACK significantly reduces this degradation.
Barua, B, Abolhasan, M, Franklin, DR & Safaei, F 2013, 'Outage Probability of Multihop Relay Networks', IEEE 9th International Wireless Communications and Mobile Computing Conference, IEEE International Conference on Wireless and Mobile Computing, Networking and Communications, IEEE, Sardinia, Italy, pp. 456-460.View/Download from: Publisher's site
In this paper we analyze the outage performance of a multihop cooperative relay network where relays in the system can change positions dynamically and use all possible links to forward the message to the next hop over Rayleigh fading channels. We derive the general closed form expression of outage probability and asymptotic coding gain of the network.
Barua, B, Abolhasan, M, Franklin, DR & Safaei, F 2013, 'SEP of Multihop Relay Networks in Nakagami-m Fading Channels', Proceedings of thte IEEE 78th Vehicular Technology Conference, IEEE Vehicular Technology Conference, IEEE, Las Vegas, NV, USA, pp. 1-5.View/Download from: Publisher's site
In this paper we analyze the error performance of a cooperative multihop parallel relay network over Nakagami-m fading channels using M-ary Phase-shift keying (MPSK) modulation. We derive the general closed form expression of the symbol error probability (SEP) and present numerical results on the performance of the network.
Hagelstein, B, Abolhasan, M, Franklin, DR & Safaei, F 2013, 'A General Performance Model for MAC Layer Cooperative Retransmission Contention Protocols', GLOBECOM, IEEE Global Telecommunications Conference, IEEE, Atlanta, USA, pp. 1584-1589.View/Download from: Publisher's site
Cooperative retransmission schemes can significantly improve transmission reliability and performance over high loss and time-varying links. However, analytically comparing performance between retransmission strategies is challenging and generally requires simplistic assumptions. This paper presents a general model for the performance of distributed, slot-based contention algorithms for opportunistic decode and forward retransmission algorithms. The model is independent of specific modulation or coding schemes and may be adapted to suit statebased transmission probability models. The model is validated through QualNet simulations.
Han, Z, Safavi-Naeini, M, Petasecca, M, Cutajar, D, Lerch, M, Franklin, DR, Jakubek, J, Zemlicka, J, Pospisil, S, Bucci, JA, Zaider, M & Rosenfeld, AB 2013, 'Brachyview: An in-body imaging system for real-time QA in HDR prostate brachytherapy', IEEE Nuclear Science Symposium Conference Record, IEEE Nuclear Science Symposium and Medical Imaging Conference, IEEE, Seoul, South Korea.View/Download from: Publisher's site
A transrectal real-time source tracking system, BrachyView, is developed by Centre for Medical Radiation Physics at University of Wollongong for treatment quality control during the high dose rate prostate brachytherapy procedure (HDR-PBT). The probe consists of a 15 × 60 mm 2 pixellated silicon detector (four Timepix detectors) encased in a cylindrical seven pinhole tungsten collimator. The source position is determined by back-projecting the source projection images through the collimator pinholes. A prototype BrachyView probe consisting of a single Timepix detector (15 × 15 mm 2 ) and a planar seven pinhole collimator is evaluated in this paper. The source position can be estimated with a maximum error of 0.2 mm on the detector plane, which translates into a maximum error of 1.42 mm within the prostate volume. This result is in good agreement with the results obtained in previously published simulation studies. © 2013 IEEE.
Li, K, Safavi-Naeini, M, Franklin, DR, Petasecca, M, Guatelli, S, Rosenfeld, AB, Hutton, BF & Lerch, MLF 2013, 'Design and development of PETiPIX: An ultra high spatial resolution small animal PET scanner', Nuclear Science Symposium and Medical Imaging Conference (NSS/MIC), 2013 IEEE, IEEE Nuclear Science Symposium and Medical Imaging Conference, IEEE, Seoul, South Korea.View/Download from: Publisher's site
PETiPIX is an ultra high spatial resolution small animal PET scanner designed for scanning of mouse brains. It utilises four state of the art pixellated silicon detectors, Timepix, in an edge-on configuration to provide a field of view (FoV) 15 mm in diameter. Each Timepix detector consists of 256×256 pixels, with pixel dimensions of 55μm×55μm× 300μm. Monte Carlo simulations have been carried to evaluate the performance of the proposed scanner. The simulated scanner achieved an overall spatial resolution of 0.29 mm (measuring at full width at half maximum (FWHM)) with a sensitivity of 0.01%. Two separate phantom studies (hot phantom and cold Jaszczk phantom) have been performed and their results demonstrate that PETiPIX is capable of achieving a high spatial resolution across its full FoV. Preliminary experiments recording recoil electrons tracks from Compton scattering events agree with the simulation results. Experiments involving two synchronised Timepix modules with a 68 Ga point source placed in the centre of the FoV demonstrated the capability of PETiPIX prototype to record true coincidence events. © 2013 IEEE.
Mukunthan, A, Cooper, C, Franklin, DR, Abolhasan, M, Safaei, F & Ross, M 2013, 'Experimental validation of the CORNER urban propagation model based on signal power measurements in a vehicular environment', Wireless Communications and Networking Conference (WCNC), 2013 IEEE, IEEE Wireless Communications and Networking Conference, IEEE, Shanghai, China, pp. 2626-2631.View/Download from: Publisher's site
CORNER is an urban propagation model which simulates the presence of buildings in city scenarios and models radio propagation as a series of reflections and diffractions around buildings. CORNER was validated in the original publication with a series of packet-delivery-ratio measurements. However, the accuracy of these measurements is limited by interference from nearby networks. This paper independently evaluates the CORNER model using signal strength measurements across three separate sites in Sydney and Wollongong. The measurements are analysed and compared with the predicted analytical estimates. The fading model is also analysed with direct measurements. A new CORNER link classification algorithm is also proposed in this paper
Rafiei, A, Maali, Y, Abolhasan, M, Franklin, DR, Safaei, F & Smith, S 2013, 'A Tuned Fuzzy Logic Relocation Model in WSNs Using Particle Swarm Optimization', Proceedings of the 2013 IEEE 78th Vehicular Technology Conference: VTC2013-Fall, IEEE Vehicular Technology Conference, IEEE-VTS, Las Vegas, USA, pp. 1-5.View/Download from: Publisher's site
In harsh and hostile environments, swift relocation of currently deployed nodes in the absence of centralized paradigm is a challenging issue in WSNs. Reducing the burden of centralized relocation paradigms by the distributed movement models comes at the price of unpleasant oscillations and excessive movements due to nodes' local and limited interactions. If the nodes' careless movements in the distributed relocation models are not properly addressed, their power will be exhausted. Therefore, in order to exert proper amount of virtual radial/angular push/pull forces among the nodes, a fuzzy logic relocation model is proposed and by considering linear combination of the presented performance metric(s)(i.e. coverage, uniformity, and average movement), its parameters are locally and globally tuned by particle swarm optimization(PSO). In order to tune fuzzy parameters locally and globally, PSO benefits respectively from nodes' neighbours within different ranges and all the given deployed area. Performance of locally and globally tuned fuzzy relocation models is compared with one another in addition to the distributed self-spreading algorithm (DSSA). It is shown that by applying PSO to the linear combinations of desired metric(s) to obtain tuned fuzzy parameters, the relocation model outperforms and/or is comparable to DSSA in one or more performance metric(s)
AlAamri, H, Safaei, F, Abolhasan, M & Franklin, DR 2012, 'Location-Based Utilization for Unidirectional Links in MANETs', Proceedings of the Eighth International Conference on Wireless and Mobile Communications, International Conference on Wireless and Mobile Communications, XPS (Xpert Publishing Services) / IARIA, Venice, Italy, pp. 248-253.
AbstractHeterogeneous Mobile Ad hoc Network(HMANET) comprises different nodes with different capabilities. Hence, transmission and receiving capabilities aredifferent. This causes unidirectionality problem. Avoidances is the most used strategy in researches to route data, e.g., Blacklist. In this paper, we proposed a strategy for on-demand routing protocols to detect unidirectional link and resolve it in timely fashion. This strategy is based on utilizing locations of nodes to filter and cache incoming RREQ packets to find reliable path to destination in the existence of unidirectional links. Simulation results show that our strategy outperforms Blacklist strategy in homogeneous and heterogeneous MANET.
Cooper, C, Hagelstein, B & Franklin, DR 2012, 'Implementation of Opportunistic Cooperative Diversity in an Ad-Hoc Network using Commodity Hardware', Wireless Communications and Mobile Computing Conference (IWCMC), 2012 8th International, ACM International Wireless Communications and Mobile Computing Conference, IEEE, Limassol, Cyprus, pp. 165-168.View/Download from: Publisher's site
Maali, Y, Rafiei, A, Abolhasan, M, Franklin, DR & Safaei, F 2012, 'A Fuzzy Logic Node Relocation Model in WSNs', 6th International Conference on Signal Processing and Communication Systems, ICSPCS 2012, International Conference on Signal Processing and Communication Systems, IEEE, Gold Coast, Australia, pp. 1-6.View/Download from: Publisher's site
Hostile and harsh environments may preclude the possibility of manual redeployment of new sensor nodes, especially in the areas suffering from widespread damage and unbalanced node deployments. Distributed local relocations of currently deployed nodes is one promising solution to this problem. By using expected global node density and force-based movement algorithms inspired by the laws of nature, it is possible to address the aforementioned challenge. Force-based movement algorithms steer nodes towards their new locations based on the aggregation of exerted virtual forces on the node from their neighborhood. Some implicit assumptions about nodesâ global status such as expected global node density are not realistic in dynamic and harsh environments. Thus, to conform to the uncertain nature and local interactions of nodes, a combination of radial-angular force fuzzy movement algorithms is suggested. The performance of the proposed model in terms of percentage of coverage, uniformity and average movement under three different boundary conditions are evaluated and compared with distributed self-spreading algorithms (DSSA). The results show that the simple fuzzy movement algorithm either outperforms or matches DSSA even if nodes don't benefit from expected global node density as in DSSA.
Mukunthan, A, Cooper, C, Safaei, F, Franklin, DR & Abolhasan, M 2012, 'Studying the Impact of the CORNER Propagation Model on VANET Routing in Urban Environments', Proceedings of the 2012 IEEE Vehicular Technology Conference (VTC Fall), IEEE Vehicular Technology Conference, IEEE, QuÃ©bec City, QC, Canada, pp. 1-5.View/Download from: Publisher's site
Odeh, N, Abolhasan, M, Safaei, F & Franklin, DR 2012, 'On the impact of RD link in resource allocation for multi-cell OFDMA cooperative relay networks with partial CSI', 2012 International Symposium on Communications and Information Technologies, ISCIT 2012, International Symposium on Communications and Information Technologies, IEEE, Gold Coast, QLD, pp. 690-695.View/Download from: Publisher's site
is paper investigates the impact of the relay-to-destination channel gain on subcarrier allocation for uplink OFDMA based cooperative relay networks using multiple amplify-and- forward (AF) relaying protocols. The closed form outage probability is derived for the system under partial channel state information (PCSI) and considering the presence of intercell interference (ICI). The results show that the impact of the link between the relay station and the destination is very low when the ICI is high. Hence, under this condition, the channel information of this link can be ignored during the resource allocation which significantly reduces the complexity of the resource allocation processes. Furthermore, this paper quantifies the level of interference at which the RD link can be ignored.
Pourashraf, P, Safaei, F & Franklin, DR 2012, 'Distributed area of interest management for large-scale immersive video conferencing', Proceedings of the 2012 IEEE International Conference on Multimedia and Expo Workshops, IEEE International Conference on Multimedia and Expo, IEEE, Melbourne, Australia, pp. 139-144.View/Download from: Publisher's site
Although video conferencing and its related applications have grown into a significant research area, the limited scalability of conference size is still a major problem. In this paper, a range of strategies for real-time area of interest (AOI) management in a 3D immersive video conference (IVC) are evaluated with the objective of minimising the required video transmission capacity and hence maximising the number of concurrent users. The paper shows that with judicious application of these techniques, the download capacity requirements of clients can be reduced by as much as 90% in a crowded virtual space.
Rafiei, A, Abolhasan, M, Franklin, DR & Safaei, F 2012, 'WSNs Coverage Hole Partial Recovery by Nodes' Constrained and Autonomous Movements Using Virtual alpha-chords', ICWMC 2012, The Eighth International Conference on Wireless and Mobile Communications, International Conference on Wireless and Mobile Communications (ICWMC), XPS (Xpert Publishing Services) / IARIA, Venice, pp. 74-80.
Safavi-Naeini, M, Franklin, DR, Petasecca, M, Lerch, MLF, Kirkham, R, Moorhead, G, Dunn, P, De Geronimo, G & Rosenfeld, AB 2012, 'Preclinical studies using a prototype high-resolution PET system with depth of interaction', 2011 IEEE Nuclear Science Symposium Conference Record, Nuclear Science Symposium Conference Record, 2011 IEEE Nuclear Science Symposium Conference Record, Anaheim, California, USA, pp. 3305-3307.View/Download from: Publisher's site
A novel high resolution PET scanner dedicated to imaging small volumes (small animals or positron mammography) has been developed. The system utilises a novel SiPM detector array coupled to a pixelated LYSO scintillator and placed in an edge-on formation around the ring. The unique design provides a more accurate placement of the Lines of Response (LoR) by measuring the Depth of Interaction (DoI) which results in a uniform spatial resolution across the whole field of view (FoV). Analytical modelling of the effect of parallax error on spatial resolution is presented. A full prototype of the system is simulated using GATE/GEANT4 with Ge-68 point sources placed at various positions within the FoV. The simulation results are compared to experimental measurements on the prototype system, and the effectiveness of the proposed approach to determining the DoI is demonstrated. The effectiveness of the DoI estimation in achieving a uniform spatial resolution across the entire FoV is demonstrated where a 30% improvement in spatial resolution close to the outer edge of the gantry ring is obtained. Preliminary images of a micro-Defrise phantom filled with F-18 obtained using the prototype system are presented and compared with a simulation of the same configuration. © 2011 IEEE.
Rafiei, A, Abolhasan, M, Franklin, DR & Safaei, F 2011, 'Boundary Node Selection Algorithms in WSNs', 36th Annual IEEE Conference on Local Computer Networks (LCN 2011), IEEE Conference on Local Computer Networks, IEEE, Bonn, Germany, pp. 251-254.View/Download from: Publisher's site
Abstract - Physical damage and/or node power exhaustion may lead to coverage holes in WSNs. Coverage holes can be directly detected by certain proximate nodes known as boundary nodes (B-nodes). Due to the sensor nodes redundant deployment and autonomous fault detection, holes are surrounded by a margin of B-nodes (MB-nodes). If all B-nodes in the margin take part in the hole recovery processes, either by increasing their transmission power or by relocating towards region of interest (ROI), the probability of collision, interference, disconnection, and isolation may increase affecting the rest of the network performance and QoS. Thus, distributed boundary node selection algorithms (BNS-Algorithms) are proposed to address these issues. BNS-algorithms allow B-nodes to self-select based on available 1-hop information extracted from nodes simple geometrical and statistical features. Our results show that the performance of the proposed distributed BNS-algorithms approaches that of their centralized counterparts.
Hagelstein, B, Abolhasan, M, Franklin, DR & Safaei, F 2010, 'An Efficient Opportunistic Cooperative Diversity Protocol for IEEE 802.11 Networks', Proceedings of the 6th International Wireless Communications and Mobile Computing Conference, International Wireless Communications and Mobile Computing Conference, ACM, Caen, France, pp. 417-421.View/Download from: Publisher's site
Opportunistic cooperation promises to enhance the user experience when streaming media over wireless devices by improving wireless network reliability at the link level. This paper presents DAFMAC, an efficient cooperative diversity partner selection algorithm for IEEE 802.11 devices. Simulation results show DAFMAC provides a significantly higher transmission reliability in poor channel conditions than traditional ARQ techniques without modifying the device hardware. Further analysis shows the low overhead of DAFMAC makes it highly competitive with other proposed cooperative retransmission mechanisms in an ad-hoc network.
Safavi-Naeini, M, Franklin, DR, Petasecca, M, Lerch, MLF, Kirkham, R, Moorhead, G, Dunn, P, De Geronimo, G & Rosenfeld, AB 2009, 'SiPM based Detector Module and Digital Data Acquisition System for PET: Initial Results', 2009 IEEE NUCLEAR SCIENCE SYMPOSIUM CONFERENCE RECORD, VOLS 1-5, IEEE Nuclear Science Symposium Conference 2009, IEEE, Orlando, FL, pp. 2679-+.View/Download from: Publisher's site
Wang, J 2009, 'Automotive Supply Chain Performance Influencing Path Analysis Based on Fuzzy Petri Net', 2009 INTERNATIONAL CONFERENCE ON INFORMATION MANAGEMENT, INNOVATION MANAGEMENT AND INDUSTRIAL ENGINEERING, VOL 1, PROCEEDINGS, 2nd International Conference on Information Management, Innovation Management and Industrial Engineering, IEEE COMPUTER SOC, Xian, PEOPLES R CHINA, pp. 359-362.View/Download from: Publisher's site
Wang, J, Abolhasan, M, Franklin, DR & Safaei, F 2009, 'OLSR-R3: Optimised link state routing with reactive route recovery', Communications, 2009. APCC 2009. 15th Asia-Pacific Conference on, APAC 2009, IEEE, Shanghai, pp. 359-362.View/Download from: Publisher's site
The optimised link state routing (OLSR) is a proactive routing protocol which relies on periodical broadcast of routing packets. However, due to the one-to-many relationship of broadcast traffic, the delivery of these packets can not be guaranteed by underlying MAC protocol, particularly in a congested condition. In this paper, the possible routing pathologies and failures of OLSR in a congested network are explored. In addition, a hybrid routing protocol which integrates OLSR with Reactive Route Recovery (OLSR-R3) is proposed to rectify the erratic routing behaviour described in this paper. Simulation studies are presented which show that the proposed solution is effective in addressing the underlining problems.
Wang, JC, Abolhasan, M, Franklin, DR & Safaei, F 2009, 'Characterising the Behaviour of IEEE 802.11 Broadcast Transmissions in Ad Hoc Wireless LANs', Proceedings of 2009 IEEE International Conference on Communications (ICC 2009), IEEE International Confernece on Communications, IEEE, Dresden, Germany, pp. 1-5.View/Download from: Publisher's site
This paper evaluates the performance of the IEEE 802.11 broadcast traffic under both saturation and non-saturation conditions. The evaluation highlights some important characteristics of IEEE 802.11 broadcast traffic as compared to corresponding unicast traffic. Moreover, it underlines the inaccuracy of the broadcast saturation model proposed by Ma and Chen due to the absence of backoff counter freeze process when channel is busy. Computer simulations are used to validate the accuracy of the new model and demonstrate the importance of capturing the freezing of backoff counter in the analytical study of IEEE 802.11 broadcast.
Wang, JC, Abolhasan, M, Franklin, DR & Safaei, F 2009, 'End-to-End path stability of reactive routing protocols in IEEE 802.11 ad hoc networks', Proceedings of 2009 IEEE 34th Conference on Local Computer Networks (LCN 2009), IEEE Conference on Local Computer Networks, IEEE, Zurich, Switzerland, pp. 499-505.View/Download from: Publisher's site
Over the years, a considerable research effort has been applied to the design of ad hoc network routing protocols. However, there is still a lack of understanding of the subtle interactions between routing protocols and lower layers in the protocol stack. In this paper, the instability which may arise when reactive routing protocols interact with the IEEE 802.11 MAC protocol is investigated. In particular, several erratic behaviours of the Ad hod On-demand Distance Vector (AODV) routing protocol in a congested IEEE 802.11 ad hoc network are demonstrated. A cross-layer solution is proposed based on an Adaptive Bulk Trigger policy and a Dynamic Window Selection scheme. Simulation studies are presented which show that the proposed solution is effective in alleviating erratic behaviour of AODV and improving the end-to-end path stability.
Abolhasan, M, Hagelstein, B & Franklin, DR 2008, 'Development and Performance Evaluation of a Flexible, Low Cost MANET', 2nd International Conference on Signal Processing and Communication Systems 2008. ICSPCS 2008., ICSOCS 2008, IEEE, Gold coast, Australia, pp. 1-6.View/Download from: Publisher's site
Performance evaluations of multi-hop ad hoc network routing protocols have been primarily conducted through analytic and simulation-based studies, which frequently fail to accurately predict real-world performance and behaviour. One reason for this is the challenge in developing low cost, representative test beds with the degree of flexibility and mobility required. We have developed a portable wireless ad hoc node (PWAN) device which establishes multi-hop routes using the OLSR routing protocol. The PWAN's performance has been investigated using two test bed configurations to evaluate its capacity under conditions of high node density in a short-range, multi-hop environment. Our results illustrate that such networks are capable of providing high quality connections when traffic density is low. However, the network link quality deteriorates dramatically as the traffic level increases, and the network topology becomes unstable until the traffic level is reduced.
Abolhasan, M, Hagelstein, B, Wang, JC-P, Franklin, DR, Safaei, F & Wysocki, T 2008, 'Development and Performance Evaluation of a Flexible, Low Cost MANET', ICSPCS: 2ND INTERNATIONAL CONFERENCE ON SIGNAL PROCESSING AND COMMUNICATION SYSTEMS, PROCEEDINGS, 2nd International Conference on Signal Processing and Communication Systems, IEEE, Gold Coast, AUSTRALIA, pp. 107-+.
Wang, J & Abolhasan, M 2008, 'Characterising the Interactions Between Unicast and Broadcast in IEEE 802.11 Ad Hoc Networks', Telecommunication Networks and Applications Conference, 2008. ATNAC 2008, ATNAC 2008, In Australasian Telecommunications Networking and Application Conference (ATNAC), Adelaide, SA, pp. 180-185.View/Download from: Publisher's site
This paper investigates the relative performance of unicast and broadcast traffic traversing a one-hop ad hoc network utilising the 802.11 DCF. An extended Markov model has been developed and validated through computer simulation, which successfully predicts the respective performance of unicast and broadcast in a variety of mixed traffic scenarios. Under heavy network traffic conditions, a significant divergence is seen to develop between the performance of the two traffic classes - in particular, when network becomes saturated, unicast traffic is effectively given higher precedence over broadcast. As a result, the network becomes dominated by unicast frames, leading to poor rates of broadcast frame delivery.
Abolhasan, M, Wang, J & Franklin, DR 2007, 'On Indoor Multi-hopping capacity of Wireless Ad-Hoc Mesh Networks', IEEE International Conference on Mobile Adhoc and Sensor Systems, MASS 2007, IEEE, Pisa, Italy, pp. 1-6.View/Download from: Publisher's site
The capacity and multi-hopping performance of ad hoc mesh networks in dynamic environment still remains an open research issue. Previous theoretical studies suggest that they do not scale in densely distributed networks. However, a study has shown that scalability and hence the multi- hopping capacity of mesh network is not only bound by the number of nodes in the network but also the number of hops . In this paper we investigate the performance of multi- hop ad hoc mesh networks, using both simulation studies and an experimental test-bed, and monitor the performance of the network as the number of hops in the network increases. Our results show that the drop in performance in multi-hopping is much more significant when the traffic levels are high. Furthermore our test-bed study shows that ad hoc mesh networks can maintain high levels of packet delivery and throughput when traffic levels are low, however, the delay experienced continues to increase after each hop.
Abolhasan, M, Wang, JC-P & Franklin, DR 2007, 'On indoor multi-hopping capacity of wireless ad-hoc mesh networks', 2007 IEEE INTERNATIONAL CONFERENCE ON MOBILE AD-HOC AND SENSOR SYSTEMS, VOLS 1-3, IEEE International Conference on Mobile Adhoc and Sensor Systems, IEEE, Pisa, ITALY, pp. 917-922.
Wang, J 2007, 'Comparison of radiated susceptibility of a digital IC between electric field coupling and magnetic field coupling based on a circuit apparoach', 2007 4TH INTERNATIONAL SYMPOSIUM ON ELECTROMAGNETIC COMPATIBILITY PROCEEDING: EMC 2007, 4th International Symposium on Electromagnetic Compatibility, IEEE, Qingdao, PEOPLES R CHINA, pp. 19-22.
Wang, JC, Abolhasan, M, Franklin, DR, Safaei, F & Lipman, J 2007, 'On Separating Route Control and Data Flows in Multi-Radio Multi-Hop Ad Hoc Network', Proceedings of the 200715th IEEE International Conference on Networks, IEEE International Conference on Networks, IEEE, Adelaide, Australia, pp. 19-24.View/Download from: Publisher's site
Ad hoc networks typically require a significant amount of routing and control information to be distributed in a timely and reliable manner throughout the network, particularly in dynamic environments. As traffic levels increase and the network becomes more heavily congested, there is an increased probability that these critical packets are lost, resulting in obsolete control information being used to make important decisions. This would further compound the problem of network congestion and lead to a very rapid loss of connectivity and throughput. Given this, we argue the solutions to these problems should not rely on putting extra bandwidth on a radio interface. Instead, we should exploit the use of multiple radios to ensure the route can be firmly established. In this paper, we propose a multiradio solution which reserves one radio channel exclusively for routing. Our simulation results have demonstrated that using a separate radio for routing protocol would dramatically improve reliability in heavily loaded ad hoc wireless networks, thereby effectively alleviating the impact of network congestion.
Wang, JC, Abolhasan, M, Safaei, F & Franklin, DR 2007, 'A Survey on Control Separation Techniques in Multi-Radio Multi-Channel MAC Protocols', Proceedings of 2007 International Symposium on Communications and Information Technologies (ISCIT 2007), International Symposium on Communications and Information Technologies, IEEE, Sydney, Australia, pp. 854-859.View/Download from: Publisher's site
The rapid diminishing in the cost of commodity wireless hardware in recent years has prompted the use of multiple radios to improve the capacity of wireless networks. However, the research has shown that the improvement obtained from using multiple radios does not solely depend on the number of radios, but primarily on how these radios can be integrated in a constructive manner. A common way of integration multiple radios is to use a dedicated radio for control. To date, a number of multi-radio MAC protocol are employing a dedicated radio to control and coordinate the other radios, though the approaches are varied from one to another. In this paper, the control separation techniques in the multi-radio multi-channel MAC have been surveyed, and a classification of control separation techniques is provided. Moreover, this study points out the open research issues and intends to spark new interests and developments in this field.
Wang, JC-P, Abolhasan, M, Franklin, DR, Safaei, F & Lipman, J 2007, 'On separating route control and data flows in multi-radio multi-hop ad hoc network', 2007 15TH IEEE INTERNATIONAL CONFERENCE ON NETWORKS, 15th IEEE International Conference on Networks, IEEE, Adelaide, AUSTRALIA, pp. 114-+.View/Download from: Publisher's site
Abolhasan, M, Wysocki, T, Franklin, DR & Lipman, J 2006, 'Capacity of Single-Radio Ad-hoc Networks for Handling High Bit Rate Real-time Internet Applications', Proceedings of the 5th Workshop on the Internet, Telecommunications and Signal Processing, WITSP '06, University of Nebraska - Lincoln, Hobart, Tasmania, pp. 1-6.
Until now, the main focus in ad hoc networking has been improving Routing and Medium Access Control (MAC) Strategies. As a result, a diverse range of routing and MAC protocols have been proposed. To evaluate these protocols, much of the existing research has been based on simulation scenarios which assume ideal channel conditions and low node and traffic densities. Therefore, despite a few studies which have shown the performance limitations of ad hoc networks theoretically, there has not been many simulation studies performed which investigate the performance of ad hoc networks under a high node and traffic density. This paper investigates the performance of ad hoc networks under a high node density and high-bit rate real-time traffic such as VoIP. Our results show that the performane of single radio ad hoc networks drops significantly as traffic density is increased. To improve the performance of ad hoc networks, a number of different strategies and research areas are described.
Franklin, DR, Xi, J & Chicharo, JF 2000, 'An improved channel model for ADSL and VDSL systems', Communication Technology Proceedings, 2000. WCC - ICCT 2000. International Conference on, International Conference on Communication Technology, IEEE, Beijing, China, pp. 30-33.View/Download from: Publisher's site
This paper examines existing channel models used with xDSL systems and identifies a key shortcoming - namely, the implicit assumption that all impulse noise originates at the transmitter. Based on extensive data collected from the local loop, a new model is proposed which addresses this problem by combining a digital filter model of the transmission line with a distributed noise source. This better reflects the nature of a real telephone line, and thus provides a more solid basis for simulation and optimisation of xDSL systems
Franklin, D, Chicharo, J & Xi, J 1999, 'A new channel model for ADSL and VDSL systems', ISSPA 1999 - Proceedings of the 5th International Symposium on Signal Processing and Its Applications, pp. 741-744.View/Download from: Publisher's site
This paper presents a new model for telephone lines which is intended for use in simulations of digital subscriber line (DSL) telecommunications systems. It combines the broadband filter characteristics of the line with an improved noise model, which acknowledges the fact that the point of ingress of impulse noise events may be anywhere along the length the line. Since impulse noise is a major impediment to DSL systems, such a model is expected to offer advantages over simpler models. A method for determining the parameters of this model is also proposed. © 1999 IEEE.
Franklin, DR & Chicharo, JF 1999, 'Paganini-a music analysis and recognition program', ISSPA 1999 - Proceedings of the 5th International Symposium on Signal Processing and Its Applications, pp. 107-110.View/Download from: Publisher's site
Music is an extremely rich and complex signal. With just four consecutive single notes of equal duration, a classical guitar can produce nearly four and a half million different progressions. With the addition of chords and changes in duration, these few notes can produce an enormous number of variations. Given this complexity, it is interesting to ask the question: is it possible for a computer program to extract enough information from the audio signal alone to reconstruct the original score? This paper proposes a novel approach to this problem entitled "Paganini", based on time-frequency analysis techniques and a neural network classifier. © 1999 IEEE.