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Associate Professor Kumbesan Sandrasegaran

Biography

Associate Professor Kumbesan Sandrasegaran (Sandy) holds a PhD in Electrical Engineering from McGill University (Canada)(1994), a Masters of Science Degree in Telecommunication Engineering from Essex University (UK)(1988) and a Bachelor of Science (Honours) Degree in Electrical Engineering (First Class) (UZ)(1985).

He was a recipient of the Canadian Commonwealth Fellowship (1990-1994) and British Council Scholarship (1987-1988).

He is a Professional Engineer (Pr.Eng) and has more than 25 years experience working either as a practioner, researcher, consultant and educator in telecommunication networks and ICT. During this time, he has focused on the planning, modelling , simulation, optimisation, security, and management of telecommunication networks.

Professional

Consultant in Mobile Networks and Telecommunications

Image of Kumbesan Sandrasegaran
Associate Professor, School of Computing and Communications
Member, A/DRsch Ctre for Real-Time Information Networks
Core Member, Centre for Real-Time Information Networks
UZ, BSc (Hons) (UZ), MSc (Essex), PhD (McGill)
Member, Institution of Electrical Engineers
 
Phone
+61 2 9514 2428
Room
CB11.08.201

Research Interests

4G Mobile Networks, Performance Testing of Networks, Networked embedded systems, wifi localization, and sensor development.

Can supervise: Yes
4G and 3G Mobile Networks (LTE-Advanced, LTE, HSPA, UMTS/WCDMA); Radio Resource Management ( Packet Scheduling, Power Control, Link Adaptation, Handover, Inter Cell Interference Mitigation, Relaying); Performance Testing of Broadband Networks and Mobile Networks; Embedded Systems for Wired and Wireless Network Applications; Wifi Localization techniques for human and object tracking; and underwater sensors development.

49110 3G Mobile Communication Systems
49099 GSM, GPRS and EDG,
49048 Wirless Networking
49xxx LTE and LTE-Advanced
Previously 48740 Communication Networks

Book Chapters

Wu, L. & Sandrasegaran, K. 2012, 'Common Radio Resource Management' in A Study on Radio Access Technology Selection Algorithms, Springer, Germany, pp. 5-11.
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Radio Resource Management (RRM) refers to a group of mechanisms that are collectively responsible for efficiently utilizing RRUs within a RAT to provide services with an acceptable level of QoS. RRM mechanisms contain Power Control (PC), Handover Control (HC), Packet Scheduling (PS), Congestion Control (CC), and Admission Control (AC).
Wu, L. & Sandrasegaran, K. 2012, 'Single Criterion Based Algorithms' in A Study on Radio Access Technology Selection Algorithms, Springer, Germany, pp. 13-22.
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Research in CRRM has many directions, e.g. policy translation and configuration, RAT selection, admission control, congestion control, horizontal handover, and packet scheduling. RAT selection algorithm is a key research area of CRRM at present. A suitable RAT selection algorithm can manage radio resources among multiple RATs more efficiently, enhance system performance, and provide better QoS to users. The RAT selection algorithm contains two parts: initial RAT selection and vertical handover (VHO). The former is used to allocate new calls to a suitable RAT and the latter is about transferring an ongoing call from its current serving RAT to a more suitable RAT.
Wu, L. & Sandrasegaran, K. 2012, 'Multiple Criteria Based Algorithms' in A Study on Radio Access Technology Selection Algorithms, Springer, Germany, pp. 23-33.
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The algorithms introduced in the last chapter use a single criterion to make RAT selection decisions. In this section, more complicated algorithms using a number of RAT selection criteria are discussed.
Wu, L. & Sandrasegaran, K. 2008, 'Overview of WiMAX Standards and Applications' in Ahson (syed), A. (eds), Wimax Standards And Applications, Taylor & Francis, Nederlands, pp. 15-34.
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Sandrasegaran, K. & Huang, X. 2008, 'Digital identity in Current Networks' in Mehdi Khosrow-Pour (ed), Encyclopedia of Information Science and Technology, Information Science Reference, Hershey, USA, pp. 1125-1132.
Sandrasegaran, K. & Li, M. 2008, 'Identity Management' in Zhang Y, Zheng J, Ma M (eds), Handbook of Research on Wireless Security, Information Science Reference, New York, USA, pp. 44-59.
The broad aim of identity management (IdM) is to manage the resourcs of an organisation (such as files, records, data, and communication infrastructure and services) and to control and manage access to those .......................................................................................................................................................................................................... process-orientated concept. The concept of IdM has begun to be applied in identities-related applications in enterprises, governments, and Web services since 2002. As the integration of heterogeneous wireless networks becomes a key issue in towards the next generation (NG) networks, IdM will be crucial to the success of NG wireless networks. A number of issues, such as mobility management, multi-provider and securities require the corresponding solutions in terms of user authentication, access control, and so forth. IdM in NG wireless networks is about managing the digital identity of a user and ensuring that users have fast, reliable, and secure access to distributed resources and services of an next generation network (NGN) and the associated service providers, across multiple systems and business contexts.
Sandrasegaran, K. & Trieu, M. 2006, 'INetwork: An Interactive Learning Tool for Communication Networks' in Nurul I. Sarkar (ed), Tools for Teaching Computer Networking and Hardware Concepts, Information Science Publishing (INFOSCI), Pennsylvania, USA, pp. 39-61.
Sandrasegaran, K. 2003, 'Diagnostic Knowledge Acquisition Based on Meta and Causal Knowledge' in Jain, R; Abraham, A; Faucher, C; van der Zwaag, B. (eds), Innovations in Knowledge Engineering, Advanced Knowledge International, Adelaide, South Australia, pp. 55-74.
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Books

Wu, L. & Sandrasegaran, K. 2012, A Study on Radio Access Technology Selection Algorithms, 1st, Springer Berlin Heidelberg, New York Dordrecht London.
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This book discusses the basic idea of Common Radio Resource Management (CRRM), especially on the Radio Access Technologies selection part of CRRM. It introduces two interaction functions (information reporting function and RRM decision support function) and four interaction degrees (from low to very high) of CRRM. Four possible CRRM topologies (CRRM server, integrated CRRM, Hierarchical CRRM, and CRRM in user terminals) are described. The book presents different Radio Access Technologies selection algorithms, including single criterion and multiple criteria based algorithms are presented and compares them. Finally, the book analyses the advantages and disadvantages of the different selection algorithms.

Conference Papers

Kong, X., Liu, L., Tran, T.P. & Sandrasegaran, K. 2014, 'Analysis of Stakeholder Concerns for Vehicle Navigation System Architecture Solution', 2014 IEEE Fifth International Conference on Communicatiosn and Electronics (ICCE), Da Nang, Vietnam, June 2014 in The Fifth International Conference on Communications and Electronics, ed Quynh, N; Tran-Gia,P; Cho D; Freeman, P, Thomson Reuters, Da Nang, Vietnam, pp. 1-6.
Daeinabi, A. & Sandrasegaran, K. 2014, 'Dynamic Almost Blank Subframe Scheme for Enhanced Intercell Interference Coordination in LTE-A Heterogeneous Networks', Vietnam, July 2014 in IEEE 5th International Conference on Communications and Electronics, ed Sandrasegaran, k, IEEE, IEEE, pp. 582-587.
In LTE-A heterogeneous network, traffic load may be distributed unequally because the transmission power of macro eNodeB (eNB) is higher than pico eNB. To address the coverage problems resulted by transmission power difference, the cell range expansion (CRE) technique has been proposed for cell selection. However, in this case, the intercell interference (ICI) problem can occur on both data and control channels when users connect to pico eNB. To mitigate ICI problem, a new dynamic almost blank subframe (ABS) scheme is proposed in this paper. In this scheme, a fuzzy logic system is deployed to monitor the system performance and then obtain the required number of ABSs. Simulation results show that the system throughput can be improved using the proposed dynamic ABS scheme.
Daeinabi, A., Sandrasegaran, K. & Zhu, X. 2013, 'Performance Evaluation of Cell Selection Techniques for Picocell in LTE-A networks', ECTI-CON 2013, Krabi, Thailand, May 2013 in 2013 10th International Conference on Electrical Engineering/Electronics, Computer, Telecommunications and Information Technology, ed Prayoot Akkaraekthalin, IEEE, Piscataway, USA, pp. 1-6.
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This survey paper provides a performance evaluation of some cell selection techniques proposed for picocells in the Long Term Evolution-Advanced (LTE-A) networks. Picocell is the focus of this study because it can be deployed in areas with high volume of traffic (such as hotspots) so as to improve the overall system capacity. A number of techniques are evaluated such as maximum Reference Signal Received Power (RSRP), Cell Range Expansion (CRE) with static offset value and adaptive offset value as well as using Almost Blank Subframes (ABS) ratio. Then a comparison is provided in terms of cell throughput, cell edge throughput and Physical Downlink Control Channel (PDCCH) outage rate. The comparison described in this paper can be useful for readers interested to select the most appreciate cell selection technique for their particular goal.
Daeinabi, A., Sandrasegaran, K. & Zhu, X. 2013, 'System Level Simulation to Evaluate the Interference in Macrocell-Picocell Downlink Systems', ACM workshop on Performance monitoring and measurement of heterogeneous wireless and wired networks, Barcelona, Spain, November 2013 in Proceedings of the 8th ACM workshop on Performance monitoring and measurement of heterogeneous wireless and wired networks, ed NA, ACM, New York, NY, US, pp. 125-131.
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System level simulations are required to evaluate the influences of cell planning, scheduling, or interference management methods on the performance of the new mobile network technologies. Interference is one of the important challenges when co-channel is used as the frequency deployment for macrocell- picocell scenario. Interference could degrade the system throughput especially for users located in cell edge regions. Therefore, a system level analysis is needed to assess the performance of macrocell-picocell scenario when an interference management technique is deployed. This paper presents a structure for system level simulation based on MATLAB to evaluate the performance of macrocell-picocell heterogeneous networks in the framework of International Mobile Communication (IMT)-Advanced evaluation. Then, the performance of an enhanced intercell interference coordination (eICIC) method is evaluated through the proposed structure.
Zhang, Q., Zhu, X., Wu, L. & Sandrasegaran, K. 2013, 'A Coloring-based Resource Allocation for OFDMA Femtocell Networks', IEEE Wireless Communications and Networking Conference, Shanghai, China, April 2013 in 2013 IEEE Wireless Communications and Networking Conference (WCNC): MAC, ed N/A, IEEE, USA, pp. 673-678.
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In order to improve the spectrum efficiency in the femtocell network and mitigate the co-tier/cross-tier interference, we propose a novel graph-theoretic scheme based on coloring algorithm for self-adaptive spectrum resource allocation in femtocells. A dynamic orthogonal spectrum sharing between macrocell and femtocell is utilized in the proposed allocation scheme to reduce the cross-tier interference. In order to mitigate the cotier interference, a graph-based clustering resource allocation (GCRA) scheme is presented. The interference graph of the femto-tier is built first based on the measurement reports of femtocell user equipments (FUEs). Then a coloring algorithm is implemented in a distributed way to construct disjoint clusters in which the frequency band can be reused to improve the spectrum efficiency. Finally, a dynamic orthogonal resource allocation is performed to avoid the inter-cluster interference. The simulation results reveal that the GCRA approach enhances the spectrum efficiency of the femtocell network, while mitigating the cotier/ cross-tier interference of the heterogeneous network.
Li, X., Zhu, X., Wu, L. & Sandrasegaran, K. 2013, 'A Distributed Non-uniform Pricing Approach for Power Optimization in Spectrum-Sharing Femtocell Network', IEEE Wireless Communications and Networking Conference, Shanghai, China, April 2013 in 2013 IEEE Wireless Communications and Networking Conference (WCNC): MAC, ed N/A, IEEE, USA, pp. 667-672.
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This paper presents a power optimization strategy based on pricing for femtocell-deployed networks. Assuming that the central Macrocell Base Station (MBS) considered as a leader sells transmission power quota to femtocells, a Stackelberg game is formulated and constraints to avoid unnecessary high transmission power are designed. The Stackelberg Equilibrium (SE) is studied and a Distributed Non-uniform Pricing (DNP)scheme where femtocells are self-organized is proposed, which needs only a little interactions. The simulation results verify the performances of DNP. It is shown that the proposed scheme performs well in terms of power optimization and interference mitigation. It also guarantees the fairness and Quality of Service (QoS) at the same time.
Patachaianand, R. & Sandrasegaran, K. 2012, 'Link Adaptation with Multiple Feedback Thresholds', IEEE 23rd International Symposium on Personal, Indoor and Mobile Radio Communications (PIMRC), Sydney, September 2012 in IEEE 23rd International Symposium on Personal, Indoor and Mobile Radio Communications (PIMRC), ed Professor Abbas Jamalipour, IEEE, Sydney, pp. 496-501.
Opportunistic scheduling in multiuser system can improves the achievable sum-rate capacity when the number of users increases. The scheduling requires the knowledge of channel state information (CSI) which is generated and sent from the users. In this chapter, the achievable sum rate of multiuser systems with multiple feedback thresholds is formulated. It is demonstrated that the system with two thresholds can achieve 98% of the full-CSI sum rate which is equivalent to around 8.5% improvement compared with the system with one threshold without any requirement for additional feedback load.
Lin, C., Sandrasegaran, K. & Reeves, S.N. 2012, 'Handover Algorithm with Joint Processing in LTE-Advanced', The 9th International Conference on Electrical Engineering/Electronics, Computer, Telecommunications and Information Technology (ECTI-CON), Phetchaburi, Thailand, May 2012 in The 9th International Conference on Electrical Engineering/Electronics, Computer, Telecommunications and Information Technology (ECTI-CON), ed Prayoot Akkaraekthalin and Kosin Chamnongthai, IEEE, Piscataway, USA, pp. 1-4.
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LTE is a purely packet-switched radio access technology and improves the legacy systems by supporting higher data rates with low latency. Release 8 of LTE has a number of gaps that prevent it from meeting the IMT-Advanced requirements for 4G. Release 10 has been proposed to fulfill the additional requirements. Coordinated multipoint (CoMP) transmission and reception is the key technique in LTE-Advanced to improve the cell-edge throughput and/or system throughput, especially joint processing (JP) in CoMP provides multiple data transmission points among multiple cooperated cells for each user equipment (UE) in the network. The standard handover algorithm in LTE could not satisfy the concept of JP in LTE-Advanced. Therefore a new handover algorithm supports JP in LTE-Advanced is necessary. In this paper, a handover algorithm with JP in LTE-A system is implemented and simulated by a C/C++ simulation tool. Simulation results show that, when compared with the standard handover algorithm in LTE system, handover algorithm with JP in LTE-Advanced is able to improve system throughput and minimize packet loss ratio (PLR) effectively. However this algorithm could lead to system capacity overload and saturated system throughput issues when dealing large amount of UEs in the network.
Sandrasegaran, K. & Patachaianand, R. 2012, 'Hybrid Scheduling Technique for Multiuser Systems', The 9th International Conference on Electrical Engineering/Electronics, Computer, Telecommunications and Information Technology (ECTI-CON), Phetchaburi, Thailand, May 2012 in The 9th International Conference on Electrical Engineering/Electronics, Computer, Telecommunications and Information Technology (ECTI-CON), ed Prayoot Akkaraekthalin and Kosin Chamnongthai, IEEE, Phetchaburi, Thailand, pp. 1-4.
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Proportional fair (PF) scheduling provides efficient allocation of resource while it results in relatively high head-of-line delay for some users in heavily loaded network. In contrast, first-in-first-out (FIFO) scheduling guarantees minimum delay for all users whereas the resource is inefficiently allocated. In this paper, a new hybrid scheduling algorithm with reduced feedback, named Hybrid PF/FIFO (HPF), which can decrease the scheduling delay and maintain efficient resource allocation is proposed. HPF behaves like PF scheduling when one or more users send(s) feedback. If none of the users send CSI feedback the resources will be allocated to the user having the largest delay similar to FIFO. Simulation results demonstrate that the proposed algorithm can achieve higher sumrate while reducing scheduling delays. The implementation of HPF does not involve any hardware upgrading.
Mohd Ramli, H., Sandrasegaran, K. & Abdullah, K. 2012, 'A Study of Packet Scheduling with Mobile Cellular Channel Impairments', The 4th International Conference on Computer and Communication Engineering, Kuala Lumpur, Malaysia, July 2012 in The 4th International Conference on Computer and Communication Engineering, ed A.H.M. Zahirul Alam, IEEE, Kuala Lumpur, Malaysia, pp. 888-893.
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Long Term Evolution-Advanced (LTE-A) is a new radio access technology that is expected to provide better experience among the mobile cellular users. It delivers multimedia services using packet switching technology. Therefore, intelligent design of packet scheduling for the LTE-A to provide Quality of Service (QoS) comparable to fixed line services becomes crucial. However, packet scheduling over the LTE-A system faces a number of challenges. This paper studies a number of low complexity real time packet scheduling algorithms developed for the legacy mobile cellular systems. In addition to that, studies on performance impact due to mobile cellular channel impairments are presented. The study aims to identify the methods used by the existing packet scheduling algorithms as well to ascertain the performance degradations on the QoS of multimedia services due to the impact of the mobile cellular channel impairments. Future works include development of a new packet scheduling algorithm to overcome detrimental effects due to LTE-A channel impairments on the QoS of multimedia services.
Lin, C., Sandrasegaran, K., Zhu, X. & Xu, Z. 2012, 'On the Performance of Capacity Integrated CoMP Handover Algorithm in LTE-Advanced', The 18th Asia-Pacific Conference on Communications (APCC 2012), Jeju island, Korea, October 2012 in The 18th Asia-Pacific Conference on Communications (APCC 2012), ed Youze Cho, IEEE, Piscataway, USA, pp. 871-876.
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Coordinated multipoint (CoMP) transmission and reception is the key technique in LTE-Advanced to improve the cell-edge throughput and/or system throughput. Joint processing (JP) in CoMP technology provides multiple data transmission points for each user among multiple cooperated radio base stations. Handover is one of the key components in cellular network mobility management. A handover algorithm is needed for making a handover decision. In this paper, a capacity integrated CoMP handover algorithm supporting JP in LTE-A system is proposed. Capacity integrated CoMP handover algorithm aims to ensure the radio resources are efficiently used in the system in both capacity and channel quality domains while reducing unnecessary feedbacks. Simulation results show that capacity integrated CoMP handover algorithm not only can improve the system throughput but also minimize the system delay, packet loss, and less total number of handovers than open literature CoMP handover algorithm.
Lin, C., Sandrasegaran, K., Zhu, X. & Xu, Z. 2012, 'Performance Evaluation of Capacity Based CoMP Handover Algorithm for LTE-Advanced', The 15th International Symposium on Wireless Personal Multimedia Communications, Taipei, Taiwan, September 2012 in The 15th International Symposium on Wireless Personal Multimedia Communications, ed Der-Jiunn Deng, Phone Lin, Hsuan-Jung Su, Gerhard Kramer, Shingo Ohmori, IEEE, Taipei, Taiwan, pp. 1-5.
Coordinated multipoint (CoMP) transmission and reception is the key technique in LTE-Advanced to improve the cell-edge throughput and/or system throughput. Joint processing (JP) in CoMP technology supports data to be available at each cell in the CoMP set. A handover algorithm is needed for making a handover decision. In this paper, a capacity based CoMP handover algorithm supporting JP in LTE-A system is proposed, evaluated and compared with open literature handover algorithm. Capacity based CoMP handover algorithm aims to emphasis the quality of target cells in both capacity and channel quality domains and ensures the radio resources are efficiently used in the system. Simulation results show that capacity based CoMP handover algorithm can effectively maximize the system throughput and minimize the system delay. However, this algorithm could have higher total number of handovers issue when dealing with large number of users in the network.
Daeinabi, A., Sandrasegaran, K. & Zhu, X. 2012, 'Survey of Intercell Interference Mitigation Techniques in LTE Downlink Networks', Australian Telecommunication Networks and Applications Conference (ATNAC 2012), Brisbane, Australia, November 2012 in Australian Telecommunication Networks and Applications Conference (ATNAC 2012), ed Professor Richard Harris, Dr Naveen Chilamkurti, Dr Mark Gregory, Professor Phuoc Tran-Gia, Professor Krys Pawlikowski, IEEE, Brisbane, Australia, pp. 1-6.
This paper presents a survey of intercell interference mitigation techniques in long term evolution (LTE) networks and focuses on algorithms which are more relevance with LTE downlink networks. A total of 20 different algorithms are reviewed and a qualitative comparison is done in terms of cell throughput and cell edge throughput. The comparison provided in this paper can be used to select the most appreciate technique for each particular goal.
Patachaianand, R. & Sandrasegaran, K. 2011, 'Opportunistic Feedback for Proportional Fair Scheduling', International Conference on Communications and Signal Processing, Kerala, India, February 2011 in Proceeding of the 2011 International Conference on Communications and Signal Processing (ICCSP 2011), ed Sameer S.M. and Suresh R., IEEE, Kerala, India, pp. 231-234.
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Proportional fair (PF) scheduling can maximise the net throughput of multiuser systems with high fairness. Typically, the scheduling requires that knowledge of channel state information (CSI) from all users be made available to the transmitter. In this paper, a feedback reporting technique in which the feedback is limited to two bits per CSI command for multiuser systems with PF scheduling is proposed. Simulation results show that the proposed scheme can achieve the same net throughput as full-CSI case and significantly outperforms one-bit feedback scheme when the feedback thresholds are optimally selected to suit the system conditions while the feedback load is dramatically reduced compared with the full-CSI.
Sandrasegaran, K., Patachaianand, R. & Madani, F.M. 2011, 'Adaptive Feedback Algorithm for OFDMA Systems', 2011 IEEE Wireless Communications and Networking Conference, Cancun, Mexico, March 2011 in Proceedings of the 2011 IEEE Wireless Communications and Networking Conference (WCNC2011 -MAC Track), ed Gorshe, S, IEEE Coomunication Society, USA, pp. 304-308.
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In this paper, a new feedback scheme is proposed for downlink OFDMA system with frequency domain packet scheduling to achieve multiuser diversity. Recent work showed that the multiuser diversity can be gained by using the so-called average best-M feedback scheme where bit-mask indicating the identification of best M subcarriers together with the average channel quality indicator of those subcarriers are reported. It has been shown that the performance of the average best-M is highly sensitive to the choice of the M value for each number of users. In this paper, an adaptive feedback scheme in which the bit-mask of feedback subcarriers is dynamically adjusted when the number of users changes is proposed. The simulation results show that the proposed scheme achieves the same performance as the average best-M scheme when the number of feedback subcarriers is optimally selected for each number of users.
Mohd Ramli, H., Sandrasegaran, K. & Basukala, R. 2011, 'HARQ Aware Scheduling Algorithm for the Downlink LTE System', International Conference on Modeling, Simulation and Applied Optimization, Kuala Lumpur, Malaysia, April 2011 in Proceeding of the International Conference on Modeling, Simulation and Applied Optimization (ICMSAO 2011), ed Prof. Watada, J, IEEE, Kuala Lumpur, pp. 1-4.
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Lin, C., Sandrasegaran, K., Mohd Ramli, H., Basukala, R., Patachaianand, R., Chen, L. & Afrin, S. 2011, 'Optimization of Handover Algorithms in 3GPP Long Term Evolution System', International Conference on Modeling, Simulation and Applied Optimization, Kuala Lumpur, Malaysia, April 2011 in Proceeding of the Fourth International Conference On Modeling, Simulation And Applied Optimization (ICMSA0 2011), ed Profesor Marzuki Khalid, IEEE, Kuala Lumpur, pp. 1-5.
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Handover in LTE is purely hard handover. The use of break-before-connect handovers reduces the complexity of the LTE network architecture. However, the hard handover may result in data being lost. A Handover algorithm is needed for making handover decision. This decision may vary over time, depending on user+s mobility. Many handover algorithms have been proposed. In this work, we optimized three well known handover algorithms in the LTE system. Simulation results show that this optimization outperforms non-optimized algorithms by minimizing the average number of handovers per UE per second while maximizing average system throughput.
Nguyen, S., Sandrasegaran, K. & Madani, F.M. 2011, 'Modelling and Simulation of Packet Scheduling in the Downlink LTE-Advanced', 17th Asia-Pacific Conference on Communications (APCC 2011), Malaysia, October 2011 in 17th Asia-Pacific Conference on Communications (APCC 2011), ed Mahamod Ismail, Hafizal Mohamad, Bohanuddin Mohaman Ali, Duratul Ain Yahya, IEEE Xplore, USA, pp. 53-57.
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LTE-Advanced, the true 4G technology of 3GPP family, is a complex radio access technology with co-existence of many types of user equipments. As it is a new technology, there are few published research focusing on modeling and simulation of LTE-Advanced system. A simulation tool is indispensable for research relating to Radio Resource Management mechanisms such as packet scheduling. This paper presents detailed descriptions of a computer simulation tool that can effectively model packet scheduling, as well as describes some of its simulation results.
Tangadpalliwar, S.A., Sandrasegaran, K., Raymond, M., Moitra, A. & Madani, F.M. 2011, 'Benchmarking Embedded Devices for Broadband Performance Testing', 2011 Ninth IEEE International Conference on Dependable, Autonomic and Secure Computing, Sydney, Australia, December 2011 in Dependable, Autonomic and Secure Computing (DASC), ed Jon T. Butler, IEEE Computer Society Press, USA, pp. 321-327.
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Real time monitoring of broadband performance parameters is critical for estimating the user experience of new broadband services like VoIP, IPTV, Gaming and Video. This information is of interest to service providers themselves for efficient network design and maintenance and government regulatory bodies for analyzing ISPs, regions and national benchmarking. A web-based system TRUEE (Tool for Real-time User Experience Estimation) is a distributed system that incorporates independent modules such as standalone measurement devices installed at customer premises, data centers, test servers and web-clients for remote monitoring and management of the system. The focus of this paper is to discuss the process of benchmarking three commercial embedded devices with PC as reference device representing an end user system for accessing broadband services. This work is part of the ongoing development process of TRUEE. This benchmarking process is of significant importance for making an informed decision on the suitability of an embedded device capable of providing desired accuracy and consistency in estimation of the broadband performance parameters. Based on literature review, online forum reviews and cost analysis three devices based on ARM viz. SheevaPlug, Texas Instrument's BeagleBoard-xM and Gumstix Overo are selected for benchmarking. Results show that Marvell's SheevaPlug outperforms the other two devices in accurately measuring the broadband parameters on its network interface.
Lin, C., Sandrasegaran, K., Mohd Ramli, H. & Xue, M. 2010, 'Requirement of Handover Modeling in the Downlink 3GPP Long Term Evolution System', International Conference on Advanced Information Networking and Applications, Perth, WA, April 2010 in 24th IEEE International Conference on Advanced Information Networking and Applications (AINA 2010) Workshops, ed O'Conner, L, IEEE Computer Society, USA, pp. 305-310.
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Long Term Evolution (LTE) is the next generation wireless system that uses Break-before-Connect technology in the handover scheme, unlike handover in the Wide-band Code Division Multiple Access (WCDMA) that uses Connect-before- Break technology. In the LTE system, handover is one of the important radio resource management schemes that are responsible for mobility of user equipments, load balancing and interference management. This paper provides detailed description on requirements involved for handover procedure in the LTE system and the feasibility to extend the current software simulation tool of the LTE system to support multiple cells for handover. This paper contributes to the identification of the requirements and specifications that are needed for further study of handover procedure in the LTE system.
Wu, L., Al Sabbagh, A., Sandrasegaran, K., Elkashlan, M. & Lin, C. 2010, 'Performance Evaluation on Common Radio Resource Management Algorithms', International Conference on Advanced Information Networking and Applications, Perth, WA, April 2010 in Proceedings of the 24th IEEE International Conference on Advanced Information Networking and Applications (AINA 2010) Workshops, ed O'Conner, L, IEEE Computer Society, California, USA, pp. 491-495.
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The next generation wireless network is expected to be a heterogeneous. The Radio Access Technology (RAT) selection algorithm, including initial RAT selection and vertical handover, is one of the key research areas in Common Radio Resource Management (CRRM). A suitable RAT selection algorithm can maximize the system performance and Quality of Service (QoS) by allocating users to the most suitable RAT in the case of two or more RATs co-located in the same coverage area. This paper evaluates the performance of three RAT selection algorithms, load balancing based using maximum resource consumption, load balancing based using minimum resource consumption and service based algorithms, in terms of traffic distribution, blocking probability, throughput and throughput fairness for a co-located GERAN/UTRAN/WLAN network. Simulation results show that in terms of blocking probability, the service based algorithm is the worst one when the traffic load is high. In terms of data throughput, the load balancing based using maximum resource consumption algorithm performs better than the other two when the traffic load is low. However, the service based algorithm outperforms the other two when the traffic load is high. In terms of throughput fairness, the service based algorithm achieves the best performance.
Xue, M., Sandrasegaran, K., Mohd Ramli, H. & Lin, C. 2010, 'Performance Analysis of Two Packet Scheduling Algorithms in Downlink 3GPP LTE System', International Conference on Advanced Information Networking and Applications, Perth, WA, April 2010 in Proceedings of the 24th IEEE International Conference on Advanced Information Networking and Applications (AINA 2010) Workshops, ed O'Conner, L, IEEE Computer Society, California, USA, pp. 915-919.
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This paper evaluates the performance of two simple packet scheduling algorithms for real-time traffic in the third generation partnership project long term evolution (3GPP LTE) system. These algorithms, known as Algorithm 1 and Algorithm 2 for this paper, were proposed to support real-time traffic in orthogonal frequency division multiple access (OFDMA) system. Simulation results show that Algorithm 1 outperforms Algorithm 2 by achieving a lower packet delay and packet loss rate while having almost similar throughput and fairness performance compared to Algorithm 2.
Wu, L., Al Sabbagh, A., Sandrasegaran, K. & Elkashlan, M. 2010, 'A User Level Markov Model for Service Based CRRM Algorithm', International Conference on Multimedia Computing and Information Technology, Sharjah, UAE, March 2010 in MCIT'2010: International Conference on Multimedia Computing and Information Technology, ed Technical Committee, IEEE, USA, pp. 41-44.
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In order to support the conceptual development of Radio Access Technology (RAT) selection algorithms, the theory of Markov model has been used. Performance metrics can be derived from the steady state probabilities of a Markov model. This paper extends a User Level Markov model for a three colocated RATs system from existing two co-located RATs Markov models. The service based RAT selection algorithm has been studied using the proposed Markov model. Numerical results obtained from the proposed Markov model are presented.
Sandrasegaran, K., Mohd Ramli, H. & Basukala, R. 2010, 'Delay-Prioritized Scheduling (DPS) for Real Time Traffic in 3GPP LTE System', WCNC, Sydney, Australia, April 2010 in 2010 IEEE Wireless Communications and Networking Conference WCNC 2010 Proceedings, ed Technical Committee, IEEE, USA, pp. 1-6.
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Given that the co-existence of multimedia applications will be a norm in the future wireless systems, their quality of service (QoS) requirements need to be guaranteed. This has imposed new challenges in the design of packet scheduling algorithms in these systems. To address those challenges, a new packet scheduling algorithm for real time (RT) traffic in downlink third generation partnership project long term evolution (3GPP LTE) system is proposed in this paper. The proposed algorithm utilizes each user++s packet delay information and its instantaneous downlink channel conditions when making scheduling decisions. Simulation results show that the proposed algorithm outperforms opportunistic scheduling and maximum-largest weighted delay first algorithms by maximizing system throughput and satisfying the QoS requirements of the RT traffic.
Mohd Ramli, H., Sandrasegaran, K., Basukala, R., Patachaianand, R., Xue, M. & Lin, C. 2010, 'Resource Allocation Technique for Video Streaming Applications in the LTE System', Annual Wireless and Optical Communications Conferen, Shanghai, China, May 2010 in Proceedings of the 19th Annual Wireless and Optical Communications Conference (WOCC 2010), ed Yu-Dong Yao, IEEE, Shanghai, China, pp. 240-244.
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Long term evolution (LTE) is the next generation wireless system that supports all IP transmission for multimedia services. The quality of service (QoS) requirements of multimedia services are one of the major challenges that need to be addressed by packet scheduling in the LTE system. This paper proposes a new resource allocation technique for real time (RT) video streaming applications in the downlink LTE system. Resource allocation, which is one of packet scheduling techniques, utilizes instantaneous downlink signal to noise ratio (SNR), packet delay and buffer information when determining the amount of radio resources to be allocated to a user. Simulation results show that the proposed technique outperforms opportunistic technique, a resource allocation technique discussed in the literature, by maximizing system throughput, efficiently utilizing the available radio resources and satisfying the QoS requirements of RT video streaming applications at a higher number of users.
Sandrasegaran, K., Patachaianand, R., Madani, F.M. & Lin, C. 2010, 'Analysis of Opportunistic Contention-Based Feedback Protocol for Downlink OFDMA', Australasian Telecommunication Networks and Applications Conference, Auckland, New Zealand, October 2010 in Australasian Telecommunication Networks and Applications Conference (ATNAC), 2010, ed Nurul I Sarkar; Adnan Al-Anbuky, IEEE, Auckland, New Zealand, pp. 72-77.
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In this paper, a new opportunistic feedback protocol for orthogonal frequency division multiple access (OFDMA) systems with mixed realtime (RT) and non-realtime (NRT) traffic is proposed and analysed. Based on the proposed feedback mechanism, a dedicated feedback channel is allocated for each RT user, while shared feedback channels are available for all NRT users. NRT users have to compete to send feedback via a contention-based random access feedback channel. The proposed feedback protocol requires a fixed amount of resource to carry feedback from all RT users and some selected NRT users. Simulation results show that the achievable throughput can be improved significantly by allocating a dedicated feedback channel for RT user compared with allocating a dedicated traffic channel. For NRT users, the achievable sum-rate of the proposed protocol when the number of users is moderate (20-50 users) approaches the ideal case when the channel quality of all users is known at the base station. The sum-rate also is close to the ideal case when the number contention minislots per subcarrier is as low as 2 minislot per subcarrier.
Deroussent, A., Sandrasegaran, K., Mohd Ramli, H. & Basukala, R. 2010, 'Radio Propagation Modelling in the Downlink LTE', Asia-Pacific Conference on Communications, Auckland, New Zealand, October 2010 in Proceedings of the 16th Asia-Pacific Conference on Communications (APCC 2010), ed Adnan Al-Anbuky, IEEE, Auckland, New Zealand, pp. 69-72.
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In order to support development of third generation partnership project long term evolution (3GPP LTE) packet scheduling algorithms, research has been conducted into several radio propagation effects. The radio channels of interest are the downlink (eNodeB to user equipment) of LTE mobile networks. Through network simulator modification and repeated testing the effects of error and delay in reporting available user mobile Signal to Noise Ratio (SNR) has been investigated. Simulation results show that errors in reported SNR will increase erroneous transmission, and the effect increased with greater numbers of users. Simulations results also show that the effect of processing delay is largely dependent on the velocity of the affected mobile user.
Sandrasegaran, K., Reeves, S.N., Mohd Ramli, H. & Basukala, R. 2010, 'Analysis of Hybrid ARQ in 3GPP LTE systems', Asia-Pacific Conference on Communications, Auckland, New Zealand, October 2010 in Proceedings of the 16th Asia-Pacific Conference on Communications (APCC 2010), ed Adnan Al-Anbuky (AUT University, New Zealand), IEEE, Auckland, New Zealand, pp. 418-423.
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The use of Hybrid ARQ in wireless networks is to provide fast re-transmits and to lower the overall error rate. The performance of HARQ schemes is a well studied field, with many results to draw from in the literature. An area that is less researched is what impact Hybrid ARQ has on LTE systems. We are, specifically, interested in looking at the system delay, but also at how HARQ behaves when used with a packet scheduler. A further area of interest is when HARQ is a drawback on the system throughput. This paper aims to look at all three of these areas.
Chen, L., Sandrasegaran, K., Basukala, R., Madani, F.M. & Lin, C. 2010, 'Impact of Soft Handover and Pilot Pollution on Video Telephony in a Commercial Network', Asia-Pacific Conference on Communications, Auckland, New Zealand, October 2010 in Proceedings of the 16th Asia-Pacific Conference on Communications (APCC 2010), ed Adnan Al-Anbuky (AUT University, New Zealand), IEEE, Auckland, New Zealand, pp. 481-486.
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Soft handover (SHO) provides better support for user mobility. The quality of service (QoS) to the mobile wireless subscribers can also grant benefits from SHO. To analyze the impact of SHO on the circuit switched (CS) video telephony (VT); real-time measurements have been conducted on a commercial WCDMA mobile network in the CBD of Sydney, Australia. Live measurement provides a practical approach to evaluate performance of commercial network. The obtained SHO gain implies that better QoS can be achieved. Furthermore, the negative impact of pilot pollution on radio link quality has been demonstrated in this paper.
Basukala, R., Mohd Ramli, H., Sandrasegaran, K. & Chen, L. 2010, 'Impact of CQI feedback rate/delay on scheduling video streaming services in LTE downlink', International Conference on Communication Technology, Nanjing, China, November 2010 in Proceedings of 12th IEEE International Conference on Communication Technology (ICCT 2010), ed Prof. Houling Zhao, Nanjing Univ. of Posts and Communications, IEEE, Nanjing, China, pp. 1349-1352.
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The major attraction of the next generation wireless systems such as the third generation partnership project (3GPP) Long Term Evolution (LTE) is the availability of high data-rate video services at high user velocities. However, it is quite a challenge to provide the required level of quality of service (QoS) and maintain the planned system performance due to limited radio resources, unreliable radio propagation channel and high user demands. This paper analyses the impact of channel quality indicator (CQI) delay and its aperiodic reporting rate on the performance of a well known scheduling algorithm serving video streaming users at different velocities. The analysis will be compared against the system having perfect and delayed channel knowledge at each scheduling instance. We then recommend the minimum rate requirement of aperiodic CQI reports to maintain the required QoS for a certain number of video streaming users.
Sandrasegaran, K., Patachaianand, R. & Madani, F.M. 2010, 'Joint Delay-Aware Opportunistic Scheduling Algorithm with Reduced Feedback to Exploit Multiuser Diversity', International Conference on Computer Applications & Industrial Electronics, Kuala Lumpur, Malaysia, December 2010 in The 2010 International Conference on Computer Applications & Industrial Electronics (ICCAIE 2010), ed Habibah Hashim, IEEE, Kuala Lumpur, Malaysia, pp. 430-435.
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The paper deals with a modified version of opportunistic scheduling algorithm that exploits multiuser diversity. It incorporates the proportional fairness scheduling policy with the first-in-first-out (FIFO) policy to obtain a hybrid policy that works well when the channel state information of each mobile user is not necessarily known. In the paper, it is proposed that the channel state information of a mobile user be transmitted to the base station only when its quality is above some threshold value; thus minimising the feedback load. It differs from previous papers in that the algorithm resorts to FIFO policy in case of feedback outages. Yet the numerical results suggest that the system capacity is depreciated only by little as compared to the proportional fairness scheme, while there is a considerable improvement in the performance delay. The additional complexity of implementation is negligible.
Nguyen, S. & Sandrasegaran, K. 2010, 'Adaptations of Proportional Fair Algorithm for Packet Scheduling in LTE-Advanced', International Conference on Communication and Vehicular Technology, Hanoi, Vietnam, December 2010 in The 2010 International Conference on Communication and Vehicular Technology (ICCVT 2010), ed Honghua Tan, Wuhan Institute of Technology, China, IEEE, Hanoi, pp. 1-6.
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3GPP has proposed LTE-Advanced as its 4G technology with many new features supplementing the current LTE technology. These new techniques lead to the demand of new Packet Scheduling Algorithms to distribute packets optimally from eNodeB to mobile stations in LTE-Advanced network. This paper presents the survey of these new algorithms that have been proposed, studies how the most well-known algorithm ++ proportional fair ++ has been propositionally modified, and discusses the new challenges for scheduling task in downlink of LTE-Advanced system.
Nguyen, S. & Sandrasegaran, K. 2010, 'Design Considerations for Packet Scheduling Simulation from LTE to LTE-Advanced', International Conference on Communication and Vehicular Technology, Hanoi, Vietnam, December 2010 in The 2010 International Conference on Communication and Vehicular Technology (ICCVT 2010), ed Honghua Tan, IEEE, Hanoi, pp. 1-4.
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LTE-Advanced, 3GPP++s proposal for IMTAdvanced or 4G, is quite complex network with coexistence of many types of user equipments in terms of radio access technology. Our current research projects have focused on LTE and we are in the process of upgrading simulation tools from LTE to LTE-Advanced. This paper discusses the design considerations to extend an existing LTE-based Packet Scheduling simulation tool to LTE-Advanced. The modifications are presented in detail to develop a new LTE-Advanced Packet Scheduling Simulator.
Sandrasegaran, K., Patachaianand, R. & Madani, F.M. 2010, 'Opportunistic Downlink Sum-Rate with Multiple Feedback Thresholds', International Conference on Computer Applications & Industrial Electronics, Kuala Lumpur, Malaysia, December 2010 in The 2010 International Conference on Computer Applications & Industrial Electronics (ICCAIE 2010), ed Habibah Hashim, IEEE, Kuala Lumpur, Malaysia, pp. 441-444.
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The achievable sum-rate capacity in multiuser systems grows as an increasing function of the number of users when opportunistic scheduling is employed. The scheduling requires the knowledge of channel state information (CSI) which is generated and sent from the users. It has been verified that the sum-rate capacity of a multiuser system with one-bit CSI feedback scheme by which each user whose channel quality is above an optimally selected threshold sends one-bit feedback has the same growth rate as that with the full CSI. However, the one-bit feedback scheme introduces non-negligible capacity loss to the achievable sum-rate. In this paper, a feedback reduction technique with multiple feedback thresholds is presented and analysed. The analysis yields closed-form expressions of the achievable sum-rate and its lower bound. The numerical results show that approximately 84% of the capacity loss can be eliminated in the system employing three optimally selected feedback thresholds. The lower-bound of the achievable sum-rate approaches the full-CSI sum-rate as the number of thresholds increases.
Sandrasegaran, K., Patachaianand, R. & Madani, F.M. 2010, 'Speed Estimation Using Transmit Power Control Commands for UMTS', International Conference on Computer Applications & Industrial Electronics, Kuala Lumpur, Malaysia, December 2010 in The 2010 International Conference on Computer Applications & Industrial Electronics (ICCAIE 2010), ed Habibah Hashim, IEEE, Kuala Lumpur, Malaysia, pp. 445-450.
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A technique to estimate user speed using transmit power control (TPC) commands is presented. We derive a close-form expression of the probability of the derivative of receive signal power exceeding a given threshold as a function of user speed, and show that it has a strong correlation with TPC pattern. The derived equation is used to map between TPC pattern and the corresponding user speed. Simulation results indicate that the proposed estimation technique can achieve accurate speed estimation over a speed range from 1 km/h to 40 km/h.
Wu, L., Sandrasegaran, K. & Elkashlan, M. 2010, 'A Markov Model for Performance Evaluation of CRRM Algorithms in a co-located GERAN/UTRAN/WLAN scenario', Wireless Communications and Networking Conference Workshops, Sydney, Australia, April 2010 in Wireless Communications and Networking Conference Workshops (WCNCW), 2010 IEEE, ed Shafi, M, IEEE, New York, USA, pp. 1-6.
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Next generation wireless networks will be heterogeneous. Multiple Radio Access Technologies (RATs) will be colocated in the same area. A challenge arising is the efficient radio resource management among overlapped RATs. The concept of Common Radio Resource Management (CRRM) has been proposed in the literature. One of the key issues of CRRM is the RAT selection algorithm. In order to support the conceptual development of Radio Access Technology (RAT) selection algorithms in heterogeneous networks, the theory of Markov model is used. This paper proposes a three-dimensional Markov model for an integrated GERAN/UTRAN/WLAN network based on the extension of existing two co-located RATs Markov models. The performance of two basic RAT selection algorithms: load balancing (LB) based and service based algorithms are evaluated in terms of call blocking probability. The numerical results obtained from our Markov model are validated by simulation results.
Patachaianand, R., Sandrasegaran, K., Mohd Ramli, H. & Basukala, R. 2009, 'Opportunistic Contention-Based Feedback Protocol for Downlink OFDMA Systems with Mixed Traffic', IEEE Pacific-Rim Conference on Multimedia, Bangkok, Thailand, December 2009 in Advances in Multimedia Information Processing - PCM 2009 - Lecture Notes in COmputer Science Volume 5879, ed Paisarn Muneesawang, Feng Wu, Itsuo Kumazawa, Athikom Roeksabutr, Mark Liao, Xiaoou Tang, Springer, Berlin / Heidelberg, pp. 1150-1155.
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An opportunistic feedback protocol is proposed for orthogonal frequency division multiple access (OFDMA) systems with mixed realtime (RT) and non-realtime (NRT) traffic. This protocol allocates a dedicated feedback channel for each RT user, while it allows all NRT users to compete to send feedback via a contention-based random access feedback channel. The proposed feedback protocol requires a fixed amount of resource to carry feedback from all RT users and some selected NRT users. The probability that NRT users attempt to send feedback is based on two parameters: a channel quality threshold, and the number of subcarriers (or clusters) whose channel quality is above the threshold. Simulation results demonstrate that allocating a dedicated feedback channel for RT user improves the achievable throughput significantly compared with allocating a dedicated traffic channel. For NRT users, the achievable sum rate of the proposed protocol when the number of users is moderate (20-50 users) approaches the ideal case when the channel quality of all users is known at the base station. The sum rate also is close to the ideal case when the number contention minislots per subcarrier is as low as 2 minislot per subcarrier.
Mohd Ramli, H., Sandrasegaran, K., Basukala, R. & Wu, L. 2009, 'Modeling and simulation of packet scheduling in the downlink long term evolution system', Asia Pacific Conference on Communications, Shanghai, China, October 2009 in Proceedings of 15th Asia-Pacific Conference on Communications, APCC 2009., ed Zhen Yang, Wenxian Yu, and Zhisheng Niu, IEEE (IEEE Catalog Number CFP09790), Curran Associates, Inc., Red Hook, NY 12571 USA, pp. 68-71.
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Long term evolution (LTE) is the next generation wireless system that uses orthogonal frequency division multiple access (OFDMA) technology in the downlink. Packet scheduling becomes paramount as the wireless systems are moving towards all IP transmissions. Since LTE system is relatively new, very little work has been published to date that can precisely model and simulate the downlink LTE system environment. This paper provides detailed descriptions on modeling and simulation of packet scheduling in the downlink LTE system using a C++ simulation tool. The tool accurately modeled the wireless system parameters and can be used for study of optimization of the LTE system.
Wu, L., Sandrasegaran, K. & Elkashlan, M. 2009, 'A system level simulation model for common radio resource management', Asia Pacific Conference on Communications, Shanghai, China, October 2009 in Proceedings of 15th Asia-Pacific Conference on Communications, APCC 2009., ed Zhen Yang, Wenxian Yu, and Zhisheng Niu, IEEE, Red Hook, USA, pp. 686-689.
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A major challenge of the future heterogeneous wireless network is the Radio Resource Management (RRM) strategy. The concept of Common RRM (CRRM) has been proposed to jointly manage radio resources among different Radio Access Technologies (RATs) in an optimized way. In order to evaluate the performance of different CRRM algorithms, a simulation model needs to be developed. This paper proposes a system level CRRM simulation model for integrated GSM/UMTS networks. In the proposed model, cell topology, user mobility, radio propagation loss, user traffic generation, and admission control are considered. The principles of system modeling and simulation presented in this paper can be used in future research on CRRM.
Wu, L., Sandrasegaran, K. & Elkashlan, M. 2009, 'Tradeoff between overall throughput and throughput fairness in network controlled cell breathing algorithm', Asia Pacific Conference on Communications, Shanghai, China, October 2009 in Proceedings of 15th Asia-Pacific Conference on Communications, APCC 2009., ed Zhen Yang, Wenxian Yu, and Zhisheng Niu, IEEE, Red Hook, USA, pp. 708-712.
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The introduction of Common Radio Resource Management (CRRM) facilitates the coordination of multiple overlapped Radio Access Technologies (RATs). A Network Controlled Cell Breathing (NCCB) RAT selection algorithm is proposed in the literature for combined GSM/UMTS networks. The setting of a proper path loss threshold is a key issue in the NCCB algorithm. In this paper, the relationship among overall downlink data throughput, throughput fairness and path loss threshold is studied. It is found that in some cases, an optimum path loss threshold value can be found to achieve better performance in terms of both overall throughput and throughput fairness. However, in other cases, a tradeoff has to be made between the overall throughput and the throughput fairness.
Basukala, R., Mohd Ramli, H. & Sandrasegaran, K. 2009, 'Performance analysis of EXP/PF and M-LWDF in downlink 3GPP LTE system', Asian Himalayas Regional International Conference on INTERNET, Kathmandu, Nepal. 3-5 Nov. 2009., November 2009 in 2009 First Asian Himalayas International Conference on Internet. AH-ICI 2009., ed Not known, IEEE, Piscataway, NJ, USA., pp. 1-5.
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This paper investigates the performance of exponential/proportional fair (EXP/PF) and maximum-largest weighted delay first (M-LWDF) scheduling algorithms in the third generation partnership project long term evolution (3GPP LTE) providing packet-switched multimedia services. It, then, identifies a suitable packet scheduling algorithm on a basis of their performance evaluation. The performance evaluation is conducted in terms of system throughput, average real time (RT) and non-real time (NRT) throughput, packet loss for RT service and fairness for NRT service. A video streaming traffic is used to model the RT service, while a web-browsing traffic is modelled for NRT service. Simulation results show that at lower load M-LWDF algorithm provides better performance than EXP/PF while as the load increases the EXP/PF gives better performance.
Wu, L., Al Sabbagh, A., Elkashlan, M. & Sandrasegaran, K. 2009, 'A User Level Markov Model for Load Balancing Based RAT Selection Algorithm', 8th International Information and Telecommunication Technologies Symposium, Florianopolis, Brazil, December 2009 in Proceedings of the 8th International Information and Telecommunication Technologies Symposium (I2TS 2009) Website, ed Fundacao Barddal de Educacao e Cultura, CD, Brazil, pp. 1-5.
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In order to support the conceptual development of Radio Access Technology (RAT) selection algorithms, one of the key issues in Common Radio Resource Management (CRRM), the theory of Markov chain model has been used. Performance metrics can be derived from the steady state probabilities of a Markov model. This paper proposes a User Level Markov model for a three co-located RATs network based on an extension from two co-located RATs Markov models introduced in the literature. The Load Balancing based RAT selection algorithm has been studied using the proposed Markov model. Numerical results obtained from the proposed Markov model are presented.
Basukala, R., Mohd Ramli, H. & Sandrasegaran, K. 2009, 'Performance of Well Known Packet Scheduling Algorithms in the Downlink 3GPP LTE System', Malaysia International Conference on Communications, Kuala Lumpur, Malaysia, December 2009 in Proceedings of the 2009 IEEE 9th Malaysia International Conference on Communications (MICC 2009), ed Hod Parman, Borhanuddin Mohd Ali, Mahamod Ismail, Hafizal Mohamad, Khairil Anuar, IEEE, Malaysia, pp. 1-5.
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This paper investigates the performance of well known packet scheduling algorithms developed for single carrier wireless systems from a real time video streaming perspective. The performance evaluation is conducted using the downlink third generation partnership project long term evolution (3GPP LTE) system as the simulation platform. This paper contributes to the identification of a suitable packet scheduling algorithm for use in the downlink 3GPP LTE system supporting video streaming services. Simulation results show that, in the downlink 3GPP LTE system supporting video streaming services, maximum-largest weighted delay first (M-LWDF) algorithm outperforms other packet scheduling algorithms by providing a higher system throughput, supporting a higher number of users and guaranteeing fairness at a satisfactory level.
Sandrasegaran, K. & Patachaianand, R. 2008, 'System-Level Modeling and Simulation of Uplink WCDMA', International Conference on Information Technology: New Generations, Las Vegas, USA, April 2008 in Proceedings of the International Conference of Infomation Technology ITNG 2008, ed Shahram Latifi, IEEE Conference Publishing Services, Los Alamitos, California, pp. 1071-1076.
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Universal Mobile Telecommunication System (UMTS) is based on WCDMA technology. The capacity of this system is difficult to manually compute because of at least two reasons. Firstly, this system is designed to support many types of services, and hence capacity calculation using classic Erlang+s capacity is not sufficient. Secondly, the capacity of such system depends on interference which is a time-varying factor, so that it is necessary to precisely model the interference; otherwise the result may be inaccurate. This paper aims to provide complete details of uplink WCDMA modeling and simulation. This proposed simulation is a dynamic system-level simulation in which important parameters such as radio propagation effects, user movement, power control and interference modeling are included. The principles of WCDMA modeling and simulation which are presented in this paper are essential tools for study and research in optimising UMTS system.
Patachaianand, R. & Sandrasegaran, K. 2008, 'Performance Study of Video Streaming in Commercial UMTS Network', IEEE International Conference on Computer and Information Technology, Sydney, Australia, November 2008 in Proceedings of the 2008 IEEE 8th International Conference on Computer and Information Technology, ed Qiang Wu, Xiangjian He, Quang Vinh Nguyen et al, IEEE, Sydney, Australia, pp. 630-633.
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This paper studies the performance of a real-time application in a live Universal Mobile Telecommunication System (UMTS) network. In the study, special user equipment (UE) capable of collecting performance parameters such as throughput and bit error rate (BER) was used. Two scenarios are considered in this paper: typical scenario when soft handover (SHO) is enabled and an extreme scenario when a situation of cell edge is created by forcing the terminal to strictly connect to one cell. The experiment results show various aspects of practical implementations and protocols which are currently used in live UMTS network. In the typical scenario, when a code with a large spreading factor (SF) is in use, the required signal-to-noise ratio target (SIRT) is low. In the cell edge case, a code with high SF of 32 is used in a poor radio condition. There results are consistent with the relevant theory.
Sandrasegaran, K. 2008, 'Using Tablet PCs for Laboratory Work in a Postgraduate Wireless Technology Subject', AAEE - Annual Conference of Australasian Association for Engineering Education, Yeppoon, Australia, December 2008 in Proceedings of the 19th Annual Conference for the Australian Association for Engineering Education, ed Llewellyn Mann, Adam Thompson, Prue Howard, Faculty of Sciences, Engineering and Health, CQU University, Rockhampton, Australia, pp. 1-6.
In this paper, we present our experiences in a UTS LTPF and HP funded project to enhance the learning outcomes of postgraduate students in Engineering Courses at University of Technology Sydney. The intended impact is that it provides learning experiences that simulate authentic professional practice and address development of students+ technical knowledge acquisition and skills development, as well as broader professional skills such as teamwork, time management, ethics and communication; and engage students with new and emerging technologies. Learning activities were set up in 49048 Wireless Networking Technology in July 2007. The use of HP tablets in a mobile class room considerably assisted students in engaging with these new technologies and gaining valuable practical skills. Class surveys carried out in November 2007 indicate that vast majority of the students (more than 90%) agree that the lab activities helped them bridge the gap between theory and practice.
Wu, L. & Sandrasegaran, K. 2007, 'A Survey on Common Radio Resource Management', Australia Conference on Wireless Broadband and Ultra Wideband Communications, Sydney, August 2007 in The Second Australia Conference on Wireless Broadband and Ultra Wideband Communications, ed Agbinya, J., Auswireless, Austraila, pp. 1-6.
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Patachaianand, R. & Sandrasegaran, K. 2007, 'Performance of Adaptive Power Control in Presence of Loop Delays', International Symposium on Communications and Information Technologies, Sydney, October 2007 in The 7th International Symposium on Communications and Information Technologies, ed Dutkiewicz, E., ISCIT, Australia, pp. 445-450.
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Patachaianand, R. & Sandrasegaran, K. 2007, 'Performance Study of New Adaptive Power Control Algorithm', International Symposium on Communications and Information Technologies, Sydney, October 2007 in The 7th International Symposium on Communications and Information Technologies, ed Dutkiewicz, E., ISCIT, Australia, pp. 505-510.
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Patachaianand, R. & Sandrasegaran, K. 2007, 'Performance Evaluation of A Multi-Interface Model for Media Independent Handover', International Symposium on Communications and Information Technologies, Sydney, October 2007 in The 7th International Symposium on Communications and Information Technologies, ed Dutkiewicz, E., ISCIT, Australia, pp. 735-738.
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Wu, L. & Sandrasegaran, K. 2007, 'A Study on RAT Selection Algorithms in Combined UMTS/GSM Networks', International Symposium on Communications and Information Technologies, Sydney, October 2007 in The 7th International Symposium on Communications and Information Technologies, ed Dutkiewicz, E., ISCIT, Australia, pp. 421-426.
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Patachaianand, R. & Sandrasegaran, K. 2007, 'Performance Comparison of Adaptive Power Control in UMTS', Australia Conference on Wireless Broadband and Ultra Wideband Communications, Sydney, August 2007 in The Second Australia Conference on Wireless Broadband and Ultra Wideband Communications, ed Agbinya, J., Auswireless07, Australia, pp. 1-5.
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Patachaianand, R. & Sandrasegaran, K. 2007, 'A Study of the Optimum Power Control Fixed Stepsize in the Presence of Power Control Loop Delay', Australia Conference on Wireless Broadband and Ultra Wideband Communications, Sydney, August 2007 in The Second Australia Conference on Wireless Broadband and Ultra Wideband Communications, ed Agbinya, J., Auswireless07, Australia, pp. 1-5.
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Wu, L. & Sandrasegaran, K. 2007, 'Forecasting Asia Pacific Mobile Market Trends Using Regression Analysis', International Conference on Mobile Business, Toronto, Ontario, Canada, July 2007 in The Sixth International Conference on Mobile Business, ed Yuan, Y., ICMB, Canada, pp. 1-6.
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Li, M., Sandrasegaran, K. & Tung, Y.T. 2007, 'A Multi-Interface Proposal for IEEE 802.21 Media Independent Handover', International Conference on Mobile Business, Toronto, Ontario, Canada, July 2007 in The Sixth International Conference on Mobile Business, ed Yuan, Y., ICMB, Canada, pp. 1-6.
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Patachaianand, R. & Sandrasegaran, K. 2007, 'An Adaptive Step Size Power Control with Transmit Power Control Commands Aided Mobility Estimation', IASTED Asian Conference on Communication Systems and Networks, Thailand, April 2007 in The Fourth IASTED Asian Conference on Communication Systems and Networks, ed Hamza, M. H., IASTED, Canada, pp. 34-39.
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Li, M., Sandrasegaran, K. & Tung, Y.T. 2007, 'Trust-Assisted Handover Decision Algorithm in Hybrid Wireless Networks', IEEE Wireless Communications and Networking Conference, Hong Kong, March 2007 in The IEEE Wireless Communications & Networking Conference 2007, ed Letaief, K. B., IEEE, Hong Kong, pp. 3535-3540.
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In next-generation (NG) hybrid wireless networks, it is believed that mobile-controlled handover (MCHO) would substitute the current handover control mechanisms in homogeneous networks. As multiple network operators with different technologies get involved, trust relationship between heterogeneous network domains become complex. The state-of-the-art multicriteria handover decision algorithms proposed for hybrid networks can not guarantee mobile host (MH)'s successful association with selected network due to lack of trust information about networks. The failure of authentication via the selected network may cause unnecessary handover attempts. In this regard, trust information of networks is considered an important factor in handover decision making. In this paper, we analyze hybrid handover issues, and present a handover decision algorithm using trust indications of networks for network selection. We also designed a hybrid wireless network topology estimating various network conditions, and had the trust-assisted algorithm compared with the latest cost-based multicriteria algorithm. The primary goal of our work is to explore how trust information of networks can contribute to hybrid handover in NG multioperator and multitechnology environments. Our simulation demonstrates whether MH makes more intelligent handover to reduce handover delay if the proposed trust-assisted handover decision algorithm is used
Li, M., Sandrasegaran, K. & Tung, Y.T. 2006, 'An Analysis of Prioritized Hybrid Interworking Requirements in Next-Generation Wireless Networks', International Conference on Computer & Communication Engineering, Kuala Lumpur, Malaysia, May 2006 in Proc of Int. Conference on Computer and Communication Engineering, ICCCE'06, ed Iftikhar Ahmad, ICCCE'06, Kuala Lumpur, Malaysia, pp. 114-120.
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Patachaianand, R. & Sandrasegaran, K. 2006, 'A New Adaptive Power Control Algorithm for UMTS', Workshop on the Internet, Telecommunication and Signal Processing, Hobart, Australia, December 2006 in The 5th Workshop on the Internet, Telecommunication and Signal Processing 2006, ed Beata J Wysocki & Tadeusz A Wysocki, WITSP'06, Wollongong, Australia, pp. 1-6.
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Patachaianand, R. & Sandrasegaran, K. 2006, 'Simulation of Call Admission Control in Multi-Traffic WCDMA Systems', International conference on Wireless Broadband and Ultra Wideband Communication, Sydney, Australia, March 2006 in AusWireless'06, ed Assoc Prof Sam Reisenfeld, UTS, Sydney, Australia, pp. 1-6.
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Li, M., Sandrasegaran, K. & Huang, X. 2005, 'Identity management in vertical handovers for UMTS-WLAN networks', International Conference on Mobile Business, Sydney, Australia, July 2005 in Proceedings of International Conference on Mobile Business (ICMB'05), ed Brookes, W; Lawrence, E; Steele, R; Chang, E, IEEE ICMB 2005, Sydney Australia, pp. 479-484.
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One motivation of mobile Next-Generation Networks (NGN) is the ubiquitous computing abilities, which provide automatic handovers for any moving computing devices in a globally networked environment. The vertical handover is defined as the process of chan
Koszek, P.E. & Sandrasegaran, K. 2005, 'Grid Architecture Storage - Utilising Grid Computing for dynamic data storage', International Conference on Information Technology and Applications, Sydney, Australia, July 2005 in Proceedings of Third International Conference On Information Technology And Applications, Vol 2, ed He, X; Hintz, T; Piccardi, M; Wu, Q; Huang, M; Tien, D, IEEE ICITA 2005, Sydney, Australia, pp. 739-742.
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Grid Architecture Storage (GAS) is based on the concept that the Grid Computing Architecture is able to be manipulated in order to facilitate data storage on the Grid. This paper describes the software that has been developed to prove this concept. The s
Haagsma, J.J., Sandrasegaran, K. & Haylock, P.J. 2005, 'Technology Assessment for Single Stage and Multi-Stage Mobile Applications', International Conference on Mobile Business, Sydney, Australia, July 2005 in Proceedings of International Conference on Mobile Business (ICMB'05), ed Brookes, W., IEEE ICMB 2005, Sydney, Australia, pp. 452-456.
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GSM, GPRS, UMTS, WLAN, WiMax and LEOs are all examples of mobile technologies that have evolved over the last decade. We have developed a simple and repeatable methodology to match mobile applications to the most appropriate technology. In this paper we
Haagsma, J.J., Haylock, R.D. & Sandrasegaran, K. 2005, 'Methodology for the Assessment of Emerging Wireless and Wireline Telecommunications Technologies', International Conference on Mobile Business, Sydney, Australia, July 2005 in Proceedings of International Conference on Mobile Business (ICMB'05), ed Brookes, W., IEEE, Piscataway, USA, pp. 599-604.
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A number of wireless and wireline telecommunication technologies have been developed over the last two decades. Assessing these telecommunication technologies in the context of their areas of application means that more successful deployments of infrastructure and services are possible. This paper outlines a systematic and rigorous methodology for selecting the most appropriate technology for a particular telecommunications application. The assessment model developed in this paper attempts to strike a balance between technical, economic, environmental, social and political factors that are all significant in the design of a telecommunications system. Using a statistical model, the target application and context are assessed and then the model presents the best matching technology solutions for the given application. This methodology is of economic and social worth, allowing faster and more cost effective deployments that meet the specific needs of a market.
Li, M. & Sandrasegaran, K. 2005, 'Network Management Challenges for Next Generation Networks', IEEE Conference on Local Computer Networks, Sydney, Australia, November 2005 in Proceedings of IEEE Conference on Local Computer Networks (LCN), ed Werner; B., IEEE LCN 2005, Sydney, Australia, pp. 593-599.
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Generally, current network management technologies follow two approaches: ITU-T s recommendations for Telecommunication Management Network (TMN) and IETF s Simple Network Management Protocol (SNMP) that favors IP networks. The applications based on these approaches are specifically targeted at a variety of independent networks including the standard Public Switched Telephone Network (PSTN), the Public Switched Data Network (PSDN), the Public Land Mobile Network (PLMN), and the Wireless Local Area Network (WLAN), etc., all of which will be integrated into a single IP-based infrastructure referred to as Next Generation Networks (NGN) in the near future. The services, network architectures and traffic pattern in NGN will dramatically differ from the current networks. The heterogeneity and complexity of NGN bring a number of challenges to its network management. In this paper, we first introduce the current network management approaches and describe some deficiencies of current solutions. Then, the network management challenges in NGN are presented and discussed. Finally, some emerging approaches towards network management in NGN are illustrated.
Sandrasegaran, K., Pillay, K. & Tsang, P. 2004, 'Forecasting the Growth of GSM Networks in Australia Using Regression Analysis', IEEE The 3rd Workshop on Internet, Telecommuications and Signal Processing, Adelaide, Australia, December 2004 in Proceedings The 3rd Workshop on Internet, Telecommunications and Signal Processing WITSP'2004, ed Beata J. Wysocki & Tadeusz A. Wysocki, IEEE, Adelaide, Australia, pp. 299-305.
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Subenthiran, S., Sandrasegaran, K. & Shalak, R. 2004, 'Requirements for Identity Management in Next Generation Networks', International Conference on Advanced Communication Technology, Phoenix Park, Korea, February 2004 in Proceedings of the 6th International Conference on Advanced Communication Technology Vol 1, ed Byeong-Nam Yoon T, Suh SY, National Computerization Agency, Seoul, South Korea, pp. 138-142.
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Identity management will become crucial to the success of Next Generation Networks (NGN). However, until now very little research has been done in this field. This paper presents tbe requirements for identity management in NGN which are currently being investigated by our research group. Our analysis is based on the characteristics and requirements of NGN architectures, services, network operators. end users, identity management requimments for web services, recent standardization efforts by various bodies, etc.
Lee, S., Sheridan-Smith, N.B., O'Neill, T., Leaney, J.R., Sandrasegaran, K. & Markovits, S. 2003, 'Managing the Enriched Experience Network - Learning-Outcome Approach to the Experimental Design Life-Cycle', Australian Telecommunication Networks and Applications Conference, Melbourne, Australia, December 2003 in Proceedings of the Australian Telecommunication Networks and Applications Conference (ATNAC'03), ed Craze, S., Australian Telecommunications CRC, CDRom only, pp. 1-5.
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Journal Articles

Li, S., Kong, X. & Sandrasegaran, K. 2014, 'Dynamic path of mobile beacon in localisation of wireless sensor network', International Journal of Sensor Networks, vol. 15, no. 2, pp. 130-141.
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Localisation of sensors within wireless sensor networks (WSNs) with the help of mobile beacons (MB) has been shown to be effective. MB is flexible, movable and a powerful replacement for static beacons. The path of a MB within a field of interest is a determining factor of the success of an algorithm. In static paths, the path is determined a priori, often following a fixed pattern and potentially limited by the concrete terrain of the field. Conversely a dynamic path, which is based on the demand of sensors in the field in a real time, is more flexible and applicable in practice. In this paper, a localisation algorithm that is based on a MB dynamic path is proposed which avoids typical complications and heavy computations to save energy in sensors. Simulation results show that the algorithm can settle sensors within a short walking distance of autonomous MB.
Lin, C., Sandrasegaran, K., Zhu, X. & Xu, Z. 2013, 'Limited Comp Handover Algorithm For LTE-Advanced', Journal of Engineering, vol. 2013, no. 1, pp. 462416-1-462416-9.
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Coordinated multipoint (CoMP) transmission and reception is the key technique in LTE-Advanced to improve the cell-edge throughput and/or system throughput. Joint processing (JP) in CoMP technology provides multiple data transmission points for each user among multiple cooperated radio base stations. Hard handover mechanism is adopted to be used in LTE-Advanced. Standard hard handover algorithm could not satisfy the concept of JP in CoMP in LTE-A due to the constraint of single connection for each user at any time. While the radio resources in the system are fixed, the more multiple data connections a user has, the more radio resources are used for the extra data connections, thus the lower capacity a system becomes. Therefore a new handover algorithm that not only supports JP in CoMP but also takes system capacity into consideration in LTE-A system is necessary. This paper proposes a new handover algorithm known as Limited CoMP Handover Algorithm to support JP in CoMP and overcome the system capacity issue. System performance of Limited CoMP Handover Algorithm is evaluated and compared with open literature handover algorithm via simulation in this paper. The simulation results show that Limited CoMP Handover Algorithm outperforms open literature handover algorithm by having shorter system delay and less system load whilst maintaining a higher system throughput in a high congested network.
Mohd Ramli, H. & Sandrasegaran, K. 2013, 'Robust Scheduling Algorithm For Guaranteed Bit Rate Services', International Journal of Mobile Communications, vol. 11, no. 1, pp. 71-88.
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This paper proposes a novel packet scheduling algorithm to overcome detrimental effects of channel impairments on the quality of service of delay-sensitive Guaranteed Bit Rate (GBR) services. The proposed algorithm prioritises the packets that require re
Al-Jaradat, H. & Sandrasegaran, K. 2013, 'Survey on the Research Challenges of Radio Resource Management in LTE-A and the Current Proposed Solutions for these Challenges', International Journal Of Computers & Technology, vol. 7, no. 3, pp. 626-637.
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Long Term Evolution-Advanced (LTE-Advanced) has been recently submitted by the 3rd Generation Partnership Project (3GPP) to the International Telecommunication Union (ITU) as one of the candidates 4G technologies. LTE-Advanced is expected to outperform its predecessor (i.e. LTE) by providing data rate up to 1Gbps and 500 Mbps in the downlink and uplink directions, respectively, also by supporting higher speed mobility (i.e. 500 km/h). In order to allow such advances in the performance, Radio Resource Management (RRM) must be effectively utilized. This paper studies the technical challenges associated with some of the RRM tasks (including Packet scheduling, interference management and handover control), in addition it presents from the open literature some of the proposed solutions to these technical challenges.
Al-Jaradat, H. & Sandrasegaran, K. 2013, 'On the Performance of PF, MLWDF and EXP/PF algorithms in LTE', International Journal Of Computers & Technology, vol. 8, no. 1, pp. 698-706.
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This paper explores the performance of three packet scheduling algorithms, namely, Proportional Fair (PF) algorithm, Exponential/Proportional Fair (EXP/PF) algorithm and Maximum Largest Weighted Delay First (MLWDF), from the real time traffic perspectives. Simulation results showed that in the downlink of the 3GPP LTE system, the MLWDF outperforms the PF and the EXP/PF algorithms in terms of packet throughput, packet-loss ratio, packet latency, fairness index and total cell spectral efficiency.
Daeinabi, A., Sandrasegaran, K. & Zhu, X. 2013, 'An Intercell Interference Coordination Scheme in LTE Downlink Networks based on User Priority and Fuzzy Logic System', International Journal of Wireless and Mobile Computing, vol. 5, no. 4, pp. 49-64.
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The Intercell Interference (ICI) problem is one of the main challenges in Long Term Evolution (LTE) downlink system. In order to deal with the ICI problem, this paper proposes a joint resource block and transmit power allocation scheme in LTE downlink networks. The proposed scheme is implemented in three phases: (1) the priority of users is calculated based on interference level, Quality of Service (QoS) and Head of Line (HoL) delay;(2) users in each cell are scheduled on the specified subbands based on their priority; and (3) eNodeBs dynamically control the transmit power using a fuzzy logic system and exchanging messages to each other. Simulation results demonstrate that the proposed priority scheme outperforms the existing Reuse Factor one (RF1) and Soft Frequency Reuse (SFR) schemes in terms of cell throughput, cell edge user throughput, delay and interference level.
Xu, Z., Sandrasegaran, K., Kong, X., Zhu, X., Hu, B., Zhao, J. & Lin, C. 2013, 'Pedestrain Monitoring System Using Wi-Fi Technology and RSSI Based Localization', International Journal of Wireless & Mobile Networks, vol. 5, no. 4, pp. 17-34.
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This paper presentsa new simple mobile tracking system based on IEEE802.11 wireless signal detection, which can be used for analyzingthe movement of pedestrian traffic. Wi-Fi packets emitted by Wi-Fi enabled smartphones are received at a monitoring station and these packets contain date, time, MAC address, and other information. The packets are received at a number of stations, distributed throughout the monitoring zone, which can measure the received signal strength. Based on the location of stations and data collected at the stations, the movement of pedestrian traffic can be analyzed. This information can be used to improve the services, such as better bus schedule time and better pavement design. In addition, this paper presents a signal strength based localization method.
Xu, Z., Sandrasegaran, K., Hu, B. & Lin, C. 2013, 'A Study of WLAN RSSI Based Distance Measurement Using EEMD', International Journal of Advanced Research in Computer Science and Software Engineering, vol. 3, no. 8, pp. 5-10.
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Received Signal Strength Indicator (RSSI) was deemed that it is not applicable for WLAN localization directly, as it is highly influenced by environment and limited by the measurement device. This distortion must be avoided to improve RSSI based distance measurement accuracy. Some method has been introduced to achieve this purpose such as Statistical Mean Value Model (SMVM) and Gauss Model (GM). This paper studies a new method namely Ensemble Empirical Mode Decomposition (EEMD) to process RSSI. A WLAN infrastructure includes one transmitter and one receiver was setup in outdoor and indoor environment to evaluate the performance of this method. The experiment consists of two aspects of transmitter movement reproduction and error analysis followed by a performance comparison with other well-known existing methods. Based on the experiment result, EEMD can efficiently normalize the RSSI reading related to distance and reproduce the movement of transmitter. In addition, EEMD presented more valid accuracy in outdoor environment than indoor environment.
Nguyen, S. & Sandrasegaran, K. 2012, 'Optimised proportional fair algorithm for longterm evolution-advanced system with multiple component carriers', IET Communications, vol. 6, no. 11, pp. 1579-1586.
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Long-term evolution-advanced (LTE-A), the true 4G technology of third Generation Partnership Project family, has a new feature that aggregates multiple LTE carriers so that users can be served on multiple component carriers (CCs). This characteristic plays an important role to increase data rate multiple times for LTE-A users with corresponding multiple CCs. However, current proposed packet scheduling (PS) algorithms ignore this effect in the effort of providing new solution that increases system performance. The modi?ed proportional fair algorithms proposed in this study can provide optimised algorithm for PS mechanism in LTE-A system as well as other technologies that use multiple carriers.
Mohd Ramli, H., Sandrasegaran, K., Basukala, R., Patachaianand, R. & Afrin, S. 2011, 'Video Streaming Performance Under Well-Known Packet Scheduling Algorithms', International Journal of Wirless and Mobile Networks, vol. 3, no. 1, pp. 25-38.
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Video streaming is becoming increasingly popular among the wireless users. However, supporting video streaming over the wireless networks is not an easy task due to the dynamic radio propagation environment, limited radio resources as well as Quality of Service (QoS) requirements of the video streaming that need to be satisfied at acceptable levels. Most studies proposed to support video streaming are computationally expensive to be used in Orthogonal Frequency Division Multiple Access (OFDMA) based wireless IP networks. This paper evaluates video streaming performance under three well-known algorithms that are more practical to be used in the OFDMA based wireless IP networks due to their reduced complexity. It is demonstrated via computer simulation that Proportional Fair (PF) algorithm outperforms other well-known algorithms by providing video streaming QoS at acceptable levels whilst maximizing cell throughput.
Mohd Ramli, H., Sandrasegaran, K. & Patachaianand, R. 2011, 'Quality-driven scheduling for Long-Term Evolution system', International Journal of Mobile Communications, vol. 9, no. 5, pp. 441-457.
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This paper proposes a novel packet scheduling algorithm that extends Opportunistic and Delay Sensitive (ODS) algorithm to simultaneously support Guaranteed Bit Rate (GBR) and Non-GBR (NGBR) services over downlink Long Term Evolution (LTE) system. The proposed algorithm utilises Channel Quality Information (CQI), average throughput, type of services, packet delay and buffer information when allocating and assigning the available Radio Resource Units (RRUs) among the users. It is demonstrated that the proposed algorithm is more efficient in terms of maximising throughput and simultaneously satisfying the Quality of Service (QoS) requirements of GBR and NGBR services at acceptable levels.
Lin, C., Sandrasegaran, K., Mohd Ramli, H. & Basukala, R. 2011, 'Optimized Performance Evaluation of LTE Hard Handover Algorithm with Average RSRP Constraint', International Journal of Wirless and Mobile Networks, vol. 3, no. 2, pp. 1-16.
Hard handover mechanism is adopted to be used in 3GPP Long Term Evolution (3GPP LTE) in order to reduce the complexity of the LTE network architecture. This mechanism comes with degradation in system throughput as well as a higher system delay. This paper proposes a new handover algorithm known as LTE Hard Handover Algorithm with Average Received Signal Reference Power (RSRP) Constraint (LHHAARC) in order to minimize number of handovers and the system delay as well as maximize the system throughput. An optimized system performance of the LHHAARC is evaluated and compared with three well-known handover algorithms via computer simulation. The simulation results show that the LHHAARC outperforms three well-known handover algorithms by having less number of average handovers per UE per second, shorter total system delay whilst maintaining a higher total system throughput.
Li, M., Sandrasegaran, K. & Tung, Y.T. 2010, 'Trust-Assisted Handover Approach in Hybrid Wireless Networks', Wireless Personal Communications, vol. 52, no. 3, pp. 477-499.
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Trust-Assisted Handover Approach in Hybrid Wireless Networks Journal Wireless Personal Communications Publisher Springer Netherlands ISSN 0929-6212 (Print) 1572-834X (Online) Issue Volume 52, Number 3 / February, 2010 DOI 10.1007/s11277-008-9634-7 Pages 477-499 Subject Collection Engineering SpringerLink Date Friday, November 28, 2008 In Next-Generation (NG) hybrid wireless networks, Mobile-Controlled Handover (MCHO) is expected to be employed as the handover control mechanism, in contrast to Network-Controlled Handover (NCHO) used in homogeneous wireless networks. As more independent network operators get involved in providing Internet access, roaming mobile users would have to deal with complex trust relationships between heterogeneous network domains. The state-of-the-art handover approaches just take into account Quality of Service (QoS), but ignore the complexities arising from the coexistence of multiple network operators in the NG networks. The existence of a complex trust relationship between networks may lead to unnecessary handover attempts in service roaming. In this regard, this paper introduces a novel approach of dynamically retrieving network trust information, and using it in MCHO. We show how network trust information can be utilised to obtain a 35% reduction in handover delay, meanwhile retain QoS in a handover. The proposed scheme does not need bulk storage in mobile handsets, and can react to changes to network topology and trust relationships dynamically. Analytical results are provided to demonstrate how roaming mobile users make more intelligent and reliable handover if implementing the proposed handover approach in a multi-operator and multi-technology environment.
Patachaianand, R. & Sandrasegaran, K. 2009, 'Proportional fair scheduling with reduced feedback', Electronics Letters, vol. 45, no. 9, pp. 472-473.
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An opportunistic feedback technique is proposed for proportional fair (PF) scheduling in a downlink multi-user system. This technique requires each mobile station, the scheduling metric of which is higher than a threshold, to send one-bit feedback for PF scheduling. The scheduler determines the optimal modulation and coding scheme for a scheduled user based on channel quality indicator (CQI) update, which is sent on a longer period than the scheduling period. The simulation results indicate that PF scheduling with the proposed update scheme can achieve similar performance as PF scheduling with full CQI feedback. The feedback overhead can be reduced in comparison with typical PF scheduling provided that an optimal CQI update period is chosen.
Li, M. & Sandrasegaran, K. 2009, 'A Proxy Based Authentication Localisation Scheme for Handover between Non Trust-Associated Domains', MOBILE COMPUTING AND COMMUNICATIONS REVIEW, vol. 13, no. 4, pp. 47-58.
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In heterogeneous wireless networks, a mobile user may have to perform handover across different network domains to maintain its data connection and quality of service. During a handover, an authentication to the mobile's home network is normally required. This may incur significant handover delay. Several fast authentication solutions based on pre-distributing security contexts between access domains have been proposed to improve handover performance. However, none of them work for a handover between two access domains without a trust relation, which can be common in a multi-operator environment. This paper presents a Proxy-Based Authentication Localisation (PBAL) scheme for handover between non trust-associated domains. The proposed PBAL scheme provides a secure and flexible means of localising authentication at a third-party entity close to visited network. This effectively avoids resorting to a mobile's home network for identity verification in a handover. Consequently, it fundamentally reduces authentication latency incurred in a inter-domain handover. The PBAL scheme does not need any changes to be made to access routers, and can be easily deployed and implemented in a cost-effective manner.
Sandrasegaran, K. & Patachaianand, R. 2008, 'Partial time delay compensation technique for UMTS adaptive power control', Electronics Letters, vol. 44, no. 7, pp. 487-488.
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A modified version of the time delay compensation (TDC) technique for universal mobile telecommunication system (UMTS) power control called partial TDC or PTDC is proposed. The new technique relaxes the need for information of the exact number of loop delays. Simulation results show that an adaptive power control algorithm using the PTDC technique can achieve better performance than that of standard UMTS power control in the presence of delays.
Gami, P.P. & Sandrasegaran, K. 2008, 'Network controlled handover scheme for heterogeneous network', Electronics Letters, vol. 44, no. 9, pp. 604-605.
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A new network controlled handover scheme for heterogeneous wireless networks is introduced. The scheme gives better handover delay performance with nearly the same amount of signalling in the network as currently known solutions. The trade-off between handover delay and the amount of signalling is optimised to achieve high performance of the vertical handover.
Wu, L. & Sandrasegaran, K. 2008, 'A Study on RAT Selection Algorithms in Combined UMTS/GSM Networks', ECTI Transactions on Electrical Engineering, Electronics and Telecommunication, vol. 6, no. 2, pp. 86-92.
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The future wireless network is expected to be a heterogeneous system, which integrates different Ra-dio Access Technologies (RATs) through a common platform. A major challenge arising from this het-erogeneous network is Radio Resource Management (RRM) strategy. Common RRM (CRRM) has been proposed in the literature to jointly manage radio re-sources among a number of overlapped RATs in an optimized way. Currently, the RAT selection algo-rithm is one of the key research areas of CRRM. This paper studies RAT selection algorithms in co-located UMTS/GSM networks. In this paper, a three-complex algorithm called IN*VG*Load is proposed based on improvements on the IN*VG algorithm. The simulation results show that the IN*VG*Load algorithm can optimize the system performance in highly loaded combined UMTS/GSM networks. A new algorithm suitable for low to medium loaded UMTS/GSM networks is also proposed and simula- tion results are presented in this paper.
Patachaianand, R. & Sandrasegaran, K. 2007, 'Consecutive Transmit Power Control Ratio Aided Adaptive Power Control for UMTS', Electronics Letters, vol. 43, no. 5, pp. 297-298.
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An adaptive power control algorithm is proposed to minimise power control errors at mobile speeds from 0 to 80 km=h in a UMTS system. The proposed algorithm adjusts its power control step size based on a new parameter called consecutive transmit power control ratio. Simulations of the proposed algorithm show that it outperforms fixed-step algorithms without any requirements for additional knowledge such as Doppler estimations.
Patachaianand, R. & Sandrasegaran, K. 2007, 'User Speed Estimation Techniques for UMTS', Electronics Letters, vol. 43, no. 19, pp. 1036-1037.
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Two new user speed estimation techniques for UMTS are proposed. They are based on a history of TPC sequences. Simulation results show that user speed estimation using a mapping equation can achieve more accurate speed estimation than using a mapping table.