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Associate Professor Kumbesan Sandrasegaran

Biography

Dr  Kumbesan Sandrasegaran (Sandy) joined UTS in 2000. He 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) (1985). He was a recipient of the Canadian Commonwealth Fellowship (1990-1994) and British Council Scholarship (1987-1988). 

.

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, CRIN - Centre for Realtime Information Networks
BSc (Hons) (UZ), UZ, MSc (Essex), PhD (McGill)
Member, Institution of Electrical Engineers
 
Phone
+61 2 9514 2428

Research Interests

Current research work focuses on  

(a) Radio Resource Management (RRM) algorithms for 4G & 5G mobile networks: Packet Scheduling, Handover, Intercell Interference, Femtocell, CRAN, D2D, Energy minimization.
(b) Engineering of novel applications with industry through the use of embedded systems, sensors and communications systems.(e.g. Mobile Tracking, Water Quality Logger, Broadband Testing )  
c) Remote sensing and smart monitoring of water quality (Water RA, Drones, Flood monitoring, Smart Metering, Smart Water Grids, Modeling and simulation of distribution systems) 
d) Performance Testing of Wireless and Wired Networks (Network traffic classification, broadband testing.

42890 4G Mobile Communications
49110 3G Mobile Communication Systems
49048 Wireless Networking

Developed 48740 Communication Networks in 2005.

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.

Chapters

Subramanian, R., Afroz, F., Sandrasegaran, K. & Kong, X. 2016, 'SON in Location-Based Services' in Self-Organized Mobile Communication Technologies and Techniques for Network Optimization, IGI global, USA.
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This chapter forays into the literature of emerging field of Self-Organization Network (SON) and its application in the area of location-based services. SON is a widely applied technology in the ad hoc networks, wireless sensor networks and automatic computer networks. This chapter deal exclusively about the projects, standards and literature of SON in the context of the cellular networks and how it can aid to achieve higher position accuracy information of the subscriber. Additionally, in this chapter a clear understanding of SON taxonomy and the guidelines for the design of SON has been presented and a comparison of SON with the existing solutions about its strength and weakness has been made in this chapter. The key research areas for further development is also highlighted in this chapter. This literature will provide comprehensive guidance for anyone interested to delve into the research of SON in cellular wireless communication and location based services.
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 syed, A. & A (eds), Wimax Standards And Applications, Taylor & Francis, Nederlands, pp. 15-34.
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Sandrasegaran, K. & Li, K. 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. & 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. & Trieu, M. 2006, 'INetwork: An Interactive Learning Tool for Communication Networks' in Sarkar, N.I. (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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Conferences

Barua, S., Lam, S.C., Ghosal, P., Xing, S. & Sandrasegaran, K. 2015, 'A survey of Direction of Arrival estimation techniques and implementation of channel estimation based on SCME', 12th International Conference on Electrical Engineering/Electronics, Computer, Telecommunications and Information Technology (ECTI-CON), IEEE, Hua Hin, Thailand.
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In this paper, basics of Direction of Arrival (DOA) estimation techniques were reviewed along with simulated results. It justifies the pros and cons of each technique. The purposes of using smart antenna system in this paper are regarded with the respect of DOA estimation, Path Delays estimation, and accurate channel estimation between a transmitter and an array of receivers. Considering the uplink transmission system, a source antenna transmits a signal and a group of antennas placed uniformly receives the signal. Then the target was to perform the common DOA estimation techniques to analyze the source signal. Since the Long Term Evolution (LTE) is the currently available standard, this model was used to estimate the channel with the help of a 2D harmonic model. Spatial Channel Model was considered for the simulation and finally, a uniform rectangular array model is comp
Daeinabi, A., Sandrasegaran, K. & Barua, S. 2015, 'A dynamic almost blank subframe scheme for video streaming traffic model in heterogeneous networks', 2015 12th International Conference on Electrical Engineering/Electronics, Computer, Telecommunications and Information Technology (ECTI-CON), IEEE, Hua Hin, pp. 1-6.
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In heterogeneous network (HetNet), the coverage area of picocell is small due to transmission power difference between macro eNodeB (eNB) and pico eNB. As a result, the traffic load is distributed unequally which yields to macrocell overloading. In order to overcome this issue, cell range expansion (CRE) technique has been proposed. However, the CRE approach can affect the downlink signal quality of the offloaded users and then these users experience high downlink interference from macro eNB on their control and data channels. Therefore, such inter-cell interference coordination (ICIC) techniques are needed to realize the promised capacity and coverage. Enhanced ICIC (eICIC) is a time domain technique to mitigate interference in HetNets using almost blank subframes (ABSs). However, the static ABS value cannot support the dynamic changing of network conditions. In this paper, a dynamic ABS scheme is proposed based on Genetic Algorithm to find the best ABS value and ABS locations in a frame to mitigate interference problem between macrocell and picocells for video streaming traffic model. Exhaustive simulation results show that the proposed scheme can improve the system performance in terms of throughput, outage probability and delay.
Lam, S., Heidari, R. & Sandrasegaran, K. 2015, 'A closed-form expression for coverage probability of random cellular network in composite Rayleigh-Lognormal fading channels', International Telecommunication Networks And Applications Conference (ITNAC), IEEE, University of New South Wales, pp. 161-165.
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oisson point process (PPP) network model in which base stations (BSs) and users have Poisson distributions has been recently used to replace grid model for analyzing the performance of cellular networks. The closed-form for the coverage probability of a typical user that connects to the closest base station (BS), however, is only found in case of high transmission signal-to-noise (SNR) and only in Rayleigh fading. This paper derives a closed-form expression for the network coverage probability in composite Rayleigh-Lognormal for both low and high SNR. The analytical results show that the coverage probability is proportional to path loss exponent coefficient, and inversely proportional to exponential function of 1 over SNR. The analytical results are also verified by Monte Carlo simulations
Lam, S., Subramanian, R., Sandrasegaran, K., Ghosal, P. & Barua, S. 2015, 'Performance of well-known frequency reuse algorithms in LTE downlink 3GPP LTE systems', International Conference on Signal Processing and Communication Systems, International Conference on Signal Processing and Communication Systems (ICSPCS), IEEE, Cairns, Australia, pp. 1-5.
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Intercell interference (ICI) is one of the major factors that limit the performance of wireless cellular network systems. Soft frequency reuse (SFR) as well as its modified algorithms such as Soft fractional frequency reuse (Soft FFR) and Distributed fractional frequency reuse (Distributed FFR) have been introduced as an effective way to optimize spectrum and control the ICI. However, the comparison between these algorithms has not fully been presented by the researchers proposing the models. This paper presents a comparison of the performance of well-known frequency reuse algorithms in term of system throughput, average packet loss ratio and average packet delay. The simulation results indicate that the simplest scheme, i.e. Soft FR, archives the highest system performance comparing to Soft FFR and Distributed FFR. Hence, it is noticed that one of the effective methods which optimize frequency reuse is to reduce the algorithm complexity.
Kong, X., Liu, L., Tran, T.P. & Sandrasegaran, K. 2014, 'Analysis of Stakeholder Concerns for Vehicle Navigation System Architecture Solution', The Fifth International Conference on Communications and Electronics, 2014 IEEE Fifth International Conference on Communicatiosn and Electronics (ICCE), Thomson Reuters, Da Nang, Vietnam, pp. 1-6.
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Daeinabi, A. & Sandrasegaran 2014, 'A Fuzzy Q-Learning Approach for Enhanced Intercell Interference Coordination in LTE-A Heterogeneous Networks', Asia-Pacific Conference on Communications, IEEE, Pattaya, Thailand, pp. 139-144.
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Since the transmission power of macro eNodeB (eNB) is higher than pico eNB in long term evolution -advanced heterogeneous network, the coverage area of picocell is small. In order to address the coverage problem, cell range expansion (CRE) technique has been recently proposed. However, CRE can lead to the downlink interference problem on both data and control channels when users are connected to pico eNB. In order to mitigate the downlink interference problem, a new dynamic almost blank subframe (ABS) scheme is proposed in this paper. In this scheme, a fuzzy q-learning approach is used to find the optimum ABS value. Simulation results show that the system performance can be improved through the proposed scheme.
Daeinabi, A., Sandrasegaran, K. & Ghosal, P. 2014, 'A Dynamic Cell Range Expansion Scheme based on Fuzzy Logic System in LTE-Advanced Heterogeneous Networks', Australasian Telecommunication Networks and Applications Conference, ATNAC, Melbourne, Australia, pp. 6-11.
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In heterogeneous network, the coverage area of picocell is usually small due to transmission power difference between macro eNodeB (eNB) and pico eNB. As a result, the traffic load is distributed unequally which yields to macrocell overloading. In order to overcome this issue, cell range expansion (CRE) technique has been recently proposed. However, the fixed CRE scheme cannot follow the UE distribution and then satisfy the system requirements. Therefore, fixed CRE scheme is unable to proportionally offload the traffic between the macrocells and picocells. In order to deal with the mentioned problem, this paper proposes a dynamic CRE scheme based on fuzzy logic system. Simulation results demonstrate that the proposed scheme can improve the system performance in terms of throughput and outage probability.
Daeinabi, A., Sandrasegaran, K. & Ghosal, P. 2014, 'An Enhanced Intercell Interference Coordination Scheme Using Fuzzy Logic Controller in LTE-Advanced Heterogeneous Networks', Proceedings of the Wireless Personal Multimedia Communications Conference, Wireless Personal Multimedia Communications Conference, IEEE, Sydney, Australia, pp. 520-525.
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In heterogeneous network, the coverage area of a picocell is small due to transmission power difference between a macro eNodeB (eNB) and a pico eNB. As a result, the traffic load is distributed unequally which leads to macrocells overloading. In order to address the coverage problem, cell range expansion (CRE) technique has been recently proposed. However, the interference can occur on both data and control channels for users located in range expanded area as they experience the low signal to interference plus noise ratio. To mitigate the interference problem, an enhanced intercell interference coordination (eICIC) scheme is proposed in this paper. In this scheme, a dynamic CRE approach is combined with a dynamic almost blank subframe (ABS) using fuzzy logic controller. Simulation results show that the system performance can be improved using the proposed eICIC scheme.
Afroz, F., Sandrasegaran, K. & Ghosal, P. 2014, 'Performance Analysis of PF, M-LWDF and EXP/PF Packet Scheduling Algorithms in 3GPP LTE Downlink', Proceedings of ATNAC, Australasian Telecommunication Networks & Applications Conference (ATNAC), IEEE, Melbourne, pp. 87-92.
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In this paper, the performance of Proportional Fair (PF), Maximum-Largest Weighted Delay First (M-LWDF) and Exponential/Proportional Fair (EXP/PF) packet scheduling algorithms has been investigated in the downlink Long Term Evolution (LTE) system. The performance evaluation is conducted in single cell with interference environment while increasing number of users in the range of 10 to 80 (Case 1) and varying users' speed in the range [3, 120] km/h (Case 2). Results show that in Case 1, M-LWDF outperforms other two algorithms in terms of average throughput, spectral efficiency, packet delay, packet loss ratio (PLR), and fairness index, and in Case 2, the performance of simulated scheduling algorithms drops noticeably with increased users' speed and M-LWDF outperforms other two algorithms in terms of average throughput, spectral efficiency, PLR, and delay.
Xing, S., Ghosal, P., Sandrasegaran, K. & Daeinabi, A. 2014, 'System Level Simulation for Femtocellular Networks', Australasian Telecommunication Networks & Applications Conference (ATNAC), IEEE, Melbourne.
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LTE is an emerging wireless data communication technology to provide broadband ubiquitous Internet access. Femtocells are included in 3GPP since Release 8 to enhance the indoor network coverage and capacity. System level simulation is used for performance evaluation of LTE-Femtocellular networks. Research works on performance optimization could not be justified since there was no common reference simulator to do so until the inception of LTE-Sim. The simulation scenarios for Femtocells in LTE-Sim encompasses two-tier macro-femto scenario but to the best of our knowledge there is no published work on coding and scripting of femtocell scenario in LTE-Sim. In this paper, the development of a femtocell scenario is discussed with simulation outcomes.
Huang, K., Kong, X. & Sandrasegaran, K. 2014, 'Analysis of the influence to productivity of software corrective maintenance using an economic model', 2014 2nd International Conference on Information Technology and Electronic Commerce, IEEE, Dalian CHINA.
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This paper presented an economic model for productivity of software corrective maintenance. The productivity is modeled using economic value of the maintenance process as the output, and the pre-committed fixed cost and variable cost as input. The relationship of the economic value and these cost components are modeled using analytical theory of investment. The values of corrective maintenance process are analyzed. A simulation approach is demonstrated to analyze the influences to the productivity in corrective maintenance. This approach provided a tool to identify and analyze the optimal parameters in productivity using the economic model and simulation.
Daeinabi, A., Sandrasegaran, K. & Zhu, X. 2013, 'System Level Simulation to Evaluate the Interference in Macrocell-Picocell Downlink Systems', Proceedings of the 8th ACM workshop on Performance monitoring and measurement of heterogeneous wireless and wired networks, ACM workshop on Performance monitoring and measurement of heterogeneous wireless and wired networks, ACM, Barcelona, Spain, 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.
Daeinabi, A., Sandrasegaran, K. & Zhu, X. 2013, 'Performance Evaluation of Cell Selection Techniques for Picocell in LTE-A networks', 2013 10th International Conference on Electrical Engineering/Electronics, Computer, Telecommunications and Information Technology, ECTI-CON 2013, IEEE, Krabi, Thailand, 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.
Li, X., Zhu, X., Wu, L. & Sandrasegaran, K. 2013, 'A Distributed Non-uniform Pricing Approach for Power Optimization in Spectrum-Sharing Femtocell Network', 2013 IEEE Wireless Communications and Networking Conference (WCNC): MAC, IEEE Wireless Communications and Networking Conference, IEEE, Shanghai, China, 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.
Zhang, Q., Zhu, X., Wu, L. & Sandrasegaran, K. 2013, 'A Coloring-based Resource Allocation for OFDMA Femtocell Networks', 2013 IEEE Wireless Communications and Networking Conference (WCNC): MAC, IEEE Wireless Communications and Networking Conference, IEEE, Shanghai, China, 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.
Ramli, H.A.M., Ismail, A.F., Abdullah, K. & Sandrasegaran, K. 2013, 'Performance analysis of two component carrier selection algorithms in the downlink LTE-A', 2013 IEEE 11th Malaysia International Conference on Communications, MICC 2013, pp. 145-150.
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This paper studies the performance of two well-known Component Carrier (CC) selection algorithms in static and dynamic allocation so as to provide satisfactory Quality of Service (QoS) of a Guaranteed Bit Rate (GBR) application. Performance evaluation is conducted using the the downlink Long Term Evolution-Advanced (LTE-A) as the simulation platform. Simulation results demonstrate the efficacy of the Random CC selection algorithm (in dynamic allocation) in optimizing the system capacity without compromising the QoS of the GBR application. However, dynamic allocation comes at the expense of an increase in signalling overhead. Future studies include identification of a new dynamic mechanism for CC selection that can reduce the signalling overhead without compromising the GBR performance. © 2013 IEEE.
Patachaianand, R. & Sandrasegaran, K. 2012, 'Link Adaptation with Multiple Feedback Thresholds', IEEE 23rd International Symposium on Personal, Indoor and Mobile Radio Communications (PIMRC), IEEE 23rd International Symposium on Personal, Indoor and Mobile Radio Communications (PIMRC), IEEE, Sydney, pp. 496-501.
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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), The 9th International Conference on Electrical Engineering/Electronics, Computer, Telecommunications and Information Technology (ECTI-CON), IEEE, Phetchaburi, Thailand, 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), The 9th International Conference on Electrical Engineering/Electronics, Computer, Telecommunications and Information Technology (ECTI-CON), 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, The 4th International Conference on Computer and Communication Engineering, 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), The 18th Asia-Pacific Conference on Communications (APCC 2012), IEEE, Jeju island, Korea, 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, The 15th International Symposium on Wireless Personal Multimedia Communications, IEEE, Taipei, Taiwan, pp. 1-5.
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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 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), Australian Telecommunication Networks and Applications Conference (ATNAC 2012), IEEE, Brisbane, Australia, pp. 1-6.
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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.
Lin, C.C., Sandrasegaran, K., Zhu, X. & Xu, Z. 2012, 'Performance evaluation of capacity based CoMP handover algorithm for LTE-Advanced', International Symposium on Wireless Personal Multimedia Communications, WPMC, pp. 236-240.
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. © 2012 NiCT.
Mohd Ramli, H., Sandrasegaran, K. & Basukala, R. 2011, 'HARQ Aware Scheduling Algorithm for the Downlink LTE System', Proceeding of the International Conference on Modeling, Simulation and Applied Optimization (ICMSAO 2011), International Conference on Modeling, Simulation and Applied Optimization, IEEE, Kuala Lumpur, Malaysia, pp. 1-4.
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Patachaianand, R. & Sandrasegaran, K. 2011, 'Opportunistic Feedback for Proportional Fair Scheduling', Proceeding of the 2011 International Conference on Communications and Signal Processing (ICCSP 2011), International Conference on Communications and Signal Processing, 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.
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), 17th Asia-Pacific Conference on Communications (APCC 2011), IEEE Xplore, Malaysia, 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.
Sandrasegaran, K., Patachaianand, R. & Madani, F.M. 2011, 'Adaptive Feedback Algorithm for OFDMA Systems', Proceedings of the 2011 IEEE Wireless Communications and Networking Conference (WCNC2011 -MAC Track), 2011 IEEE Wireless Communications and Networking Conference, IEEE Coomunication Society, Cancun, Mexico, 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.
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', Proceeding of the Fourth International Conference On Modeling, Simulation And Applied Optimization (ICMSA0 2011), International Conference on Modeling, Simulation and Applied Optimization, IEEE, Kuala Lumpur, Malaysia, 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 users 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.
Tangadpalliwar, S.A., Sandrasegaran, K., Raymond, M., Moitra, A. & Madani, F.M. 2011, 'Benchmarking Embedded Devices for Broadband Performance Testing', Dependable, Autonomic and Secure Computing (DASC), 2011 Ninth IEEE International Conference on Dependable, Autonomic and Secure Computing, IEEE Computer Society Press, Sydney, Australia, 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.
Wu, L., Al Sabbagh, A., Sandrasegaran, K., Elkashlan, M. & Lin, C. 2010, 'Performance Evaluation on Common Radio Resource Management Algorithms', Proceedings of the 24th IEEE International Conference on Advanced Information Networking and Applications (AINA 2010) Workshops, International Conference on Advanced Information Networking and Applications, IEEE Computer Society, Perth, WA, 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', Proceedings of the 24th IEEE International Conference on Advanced Information Networking and Applications (AINA 2010) Workshops, International Conference on Advanced Information Networking and Applications, IEEE Computer Society, Perth, WA, 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.
Sandrasegaran, K., Mohd Ramli, H. & Basukala, R. 2010, 'Delay-Prioritized Scheduling (DPS) for Real Time Traffic in 3GPP LTE System', 2010 IEEE Wireless Communications and Networking Conference WCNC 2010 Proceedings, WCNC, IEEE, Sydney, Australia, 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 userâs 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.
Sandrasegaran, K., Patachaianand, R. & Madani, F.M. 2010, 'Opportunistic Downlink Sum-Rate with Multiple Feedback Thresholds', The 2010 International Conference on Computer Applications & Industrial Electronics (ICCAIE 2010), International Conference on Computer Applications & Industrial Electronics, 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', The 2010 International Conference on Computer Applications & Industrial Electronics (ICCAIE 2010), International Conference on Computer Applications & Industrial Electronics, 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.
Lin, C., Sandrasegaran, K., Mohd Ramli, H. & Xue, M. 2010, 'Requirement of Handover Modeling in the Downlink 3GPP Long Term Evolution System', 24th IEEE International Conference on Advanced Information Networking and Applications (AINA 2010) Workshops, International Conference on Advanced Information Networking and Applications, IEEE Computer Society, Perth, WA, 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. 2010, 'A User Level Markov Model for Service Based CRRM Algorithm', MCIT'2010: International Conference on Multimedia Computing and Information Technology, International Conference on Multimedia Computing and Information Technology, IEEE, Sharjah, UAE, 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.
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', Proceedings of the 19th Annual Wireless and Optical Communications Conference (WOCC 2010), Annual Wireless and Optical Communications Conferen, 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 (ATNAC), 2010, Australasian Telecommunication Networks and Applications Conference, 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.
Sandrasegaran, K., Reeves, S.N., Mohd Ramli, H. & Basukala, R. 2010, 'Analysis of Hybrid ARQ in 3GPP LTE systems', Proceedings of the 16th Asia-Pacific Conference on Communications (APCC 2010), Asia-Pacific Conference on Communications, 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', Proceedings of the 16th Asia-Pacific Conference on Communications (APCC 2010), Asia-Pacific Conference on Communications, 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', Proceedings of 12th IEEE International Conference on Communication Technology (ICCT 2010), International Conference on Communication Technology, 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', The 2010 International Conference on Computer Applications & Industrial Electronics (ICCAIE 2010), International Conference on Computer Applications & Industrial Electronics, 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', The 2010 International Conference on Communication and Vehicular Technology (ICCVT 2010), International Conference on Communication and Vehicular Technology, IEEE, Hanoi, Vietnam, 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 â proportional fair â 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', The 2010 International Conference on Communication and Vehicular Technology (ICCVT 2010), International Conference on Communication and Vehicular Technology, IEEE, Hanoi, Vietnam, pp. 1-4.
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LTE-Advanced, 3GPPâs 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.
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 (WCNCW), 2010 IEEE, Wireless Communications and Networking Conference Workshops, IEEE, Sydney, Australia, 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.
Deroussent, A., Sandrasegaran, K., Mohd Ramli, H. & Basukala, R. 2010, 'Radio Propagation Modelling in the Downlink LTE', Proceedings of the 16th Asia-Pacific Conference on Communications (APCC 2010), Asia-Pacific Conference on Communications, 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. & Patachaianand, R. 2010, 'Speed estimation using transmit power control commands for UMTS', ICCAIE 2010 - 2010 International Conference on Computer Applications and Industrial Electronics, pp. 447-452.
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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. © 2010 IEEE.
Sandrasegaran, K. & Patachaianand, R. 2010, 'Opportunistic downlink sum-rate with multiple feedback thresholds', ICCAIE 2010 - 2010 International Conference on Computer Applications and Industrial Electronics, pp. 443-446.
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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 CSL 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. © 2010 IEEE.
Patachaianand, R., Sandrasegaran, K., Mohd Ramli, H. & Basukala, R. 2009, 'Opportunistic Contention-Based Feedback Protocol for Downlink OFDMA Systems with Mixed Traffic', Advances in Multimedia Information Processing - PCM 2009 - Lecture Notes in COmputer Science Volume 5879, IEEE Pacific-Rim Conference on Multimedia, Springer, Bangkok, Thailand, 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', Proceedings of 15th Asia-Pacific Conference on Communications, APCC 2009., Asia Pacific Conference on Communications, IEEE (IEEE Catalog Number CFP09790), Shanghai, China, 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', Proceedings of 15th Asia-Pacific Conference on Communications, APCC 2009., Asia Pacific Conference on Communications, IEEE, Shanghai, China, 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', Proceedings of 15th Asia-Pacific Conference on Communications, APCC 2009., Asia Pacific Conference on Communications, IEEE, Shanghai, China, 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.
Wu, L., Al Sabbagh, A., Elkashlan, M. & Sandrasegaran, K. 2009, 'A User Level Markov Model for Load Balancing Based RAT Selection Algorithm', Proceedings of the 8th International Information and Telecommunication Technologies Symposium (I2TS 2009) Website, 8th International Information and Telecommunication Technologies Symposium, CD, Florianopolis, Brazil, pp. 1-5.
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', Proceedings of the 2009 IEEE 9th Malaysia International Conference on Communications (MICC 2009), Malaysia International Conference on Communications, IEEE, Kuala Lumpur, 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.
Basukala, R., Mohd Ramli, H. & Sandrasegaran, K. 2009, 'Performance analysis of EXP/PF and M-LWDF in downlink 3GPP LTE system', 2009 First Asian Himalayas International Conference on Internet. AH-ICI 2009., Asian Himalayas Regional International Conference on INTERNET, IEEE, Kathmandu, Nepal. 3-5 Nov. 2009., 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.
Ramli, H.A.M., Basukala, R., Sandrasegaran, K. & Patachaianand, R. 2009, 'Performance of well known packet scheduling algorithms in the downlink 3GPP LTE system', Proceedings - MICC 2009: 2009 IEEE 9th Malaysia International Conference on Communications with a Special Workshop on Digital TV Contents, pp. 815-820.
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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. ©2009 IEEE.
Wu, L., Sandrasegaran, K. & Mohd Ramli, H. 2008, 'A Study on Load Threshold Setting Issue in Load Based Common Radio Resource Management', ICIMU CD, The 4th International Conference on Information Technology and Multimedia at UNITEN, ICIMU, Malaysia, pp. 244-249.
Sandrasegaran, K. & Patachaianand, R. 2008, 'System-Level Modeling and Simulation of Uplink WCDMA', Proceedings of the International Conference of Infomation Technology ITNG 2008, International Conference on Information Technology: New Generations, IEEE Conference Publishing Services, Las Vegas, USA, 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 Erlangs 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', Proceedings of the 2008 IEEE 8th International Conference on Computer and Information Technology, IEEE International Conference on Computer and Information Technology, 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', Proceedings of the 19th Annual Conference for the Australian Association for Engineering Education, AAEE - Annual Conference of Australasian Association for Engineering Education, Faculty of Sciences, Engineering and Health, CQU University, Yeppoon, 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', The Second Australia Conference on Wireless Broadband and Ultra Wideband Communications, Australia Conference on Wireless Broadband and Ultra Wideband Communications, Auswireless, Sydney, pp. 1-6.
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Patachaianand, R. & Sandrasegaran, K. 2007, 'Performance of Adaptive Power Control in Presence of Loop Delays', The 7th International Symposium on Communications and Information Technologies, International Symposium on Communications and Information Technologies, ISCIT, Sydney, pp. 445-450.
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Patachaianand, R. & Sandrasegaran, K. 2007, 'Performance Study of New Adaptive Power Control Algorithm', The 7th International Symposium on Communications and Information Technologies, International Symposium on Communications and Information Technologies, ISCIT, Sydney, pp. 505-510.
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Patachaianand, R. & Sandrasegaran, K. 2007, 'Performance Evaluation of A Multi-Interface Model for Media Independent Handover', The 7th International Symposium on Communications and Information Technologies, International Symposium on Communications and Information Technologies, ISCIT, Sydney, pp. 735-738.
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Wu, L. & Sandrasegaran, K. 2007, 'A Study on RAT Selection Algorithms in Combined UMTS/GSM Networks', The 7th International Symposium on Communications and Information Technologies, International Symposium on Communications and Information Technologies, ISCIT, Sydney, pp. 421-426.
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Patachaianand, R. & Sandrasegaran, K. 2007, 'Performance Comparison of Adaptive Power Control in UMTS', The Second Australia Conference on Wireless Broadband and Ultra Wideband Communications, Australia Conference on Wireless Broadband and Ultra Wideband Communications, Auswireless07, Sydney, 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', The Second Australia Conference on Wireless Broadband and Ultra Wideband Communications, Australia Conference on Wireless Broadband and Ultra Wideband Communications, Auswireless07, Sydney, pp. 1-5.
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Wu, L. & Sandrasegaran, K. 2007, 'Forecasting Asia Pacific Mobile Market Trends Using Regression Analysis', The Sixth International Conference on Mobile Business, International Conference on Mobile Business, ICMB, Toronto, Ontario, Canada, pp. 1-6.
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Li, K., Sandrasegaran, K. & Tung, T.T. 2007, 'A Multi-Interface Proposal for IEEE 802.21 Media Independent Handover', The Sixth International Conference on Mobile Business, International Conference on Mobile Business, ICMB, Toronto, Ontario, 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', The Fourth IASTED Asian Conference on Communication Systems and Networks, IASTED Asian Conference on Communication Systems and Networks, IASTED, Thailand, pp. 34-39.
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Li, K., Sandrasegaran, K. & Tung, T.T. 2007, 'Trust-Assisted Handover Decision Algorithm in Hybrid Wireless Networks', The IEEE Wireless Communications & Networking Conference 2007, IEEE Wireless Communications and Networking Conference, 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, K., Sandrasegaran, K. & Tung, T.T. 2006, 'An Analysis of Prioritized Hybrid Interworking Requirements in Next-Generation Wireless Networks', Proc of Int. Conference on Computer and Communication Engineering, ICCCE'06, International Conference on Computer & Communication Engineering, 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', The 5th Workshop on the Internet, Telecommunication and Signal Processing 2006, Workshop on the Internet, Telecommunication and Signal Processing, WITSP'06, Hobart, Australia, pp. 1-6.
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Patachaianand, R. & Sandrasegaran, K. 2006, 'Simulation of Call Admission Control in Multi-Traffic WCDMA Systems', AusWireless'06, International conference on Wireless Broadband and Ultra Wideband Communication, UTS, Sydney, Australia, pp. 1-6.
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Ye, M. & Sandrasegaran, K. 2006, 'Teaching about Firewall Concepts using the iNetwork Simulator', The 7th International Conference on Information Technology Based Higher Education and Training 2006, Information Technology Based Higher Education and Training, 2006. ITHET '06. 7th International Conference on, IEEE, Sydney, australia, pp. 889-892.
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The iNetwork Simulator is a software application created provides a user-friendly graphical interface for building and simulating basic communication networks. Such networks can comprise of devices such as workstations, servers, switches and routers. This project enhances the iNetwork Simulator application by allowing firewalls to be simulated. Firewalls play in integral part in the security infrastructure of many organisations (and individuals). Being able to interact with a virtual firewall would benefit many students with an interest in the security-related aspects of communication networks. The firewall component was implemented using the Microsoft .NET Framework and the C# programming language (the same platform used to originally develop the iNetwork Simulator application). The full software development lifecycle was followed during the course of this project
Patachaianand, R. & Sandrasegaran, K. 2006, 'Simulation of call admission control in multi-traffics WCDMA system', Proceedings of the 1st IEEE International Conference on Wireless Broadband and Ultra Wideband Communications, AusWireless 2006, pp. 590-595.
Wideband Code Division Multiple Access (WCDMA) is the multiple access technique used in the third generation of mobile telecommunication (3G) systems. Capacity of this technique does not have an exact limit. The maximum capacity of WCDMA depends on current interference in the system. However, high interference causes the system a degradation of quality-of-service (QoS). Therefore, a mechanism to suppress the interference is vital. Call Admission Control (CAC) is a mechanism capable for maintaining the interference below a threshold. This report presents a basic simulation description necessary for demonstrating a simulation of a simple WCDMA system with CAC. The report includes some fundamental theories about a WCDMA system, traffic modeling, and CAC algorithms. Some simulation results are also given. The simulation results show that the blocking probability depends on the average number of users and thresholds. The results also show that much data traffic is blocked although the capacity is still available. This leads us to realize the importance of a mechanism to handle data traffic in the multi-traffics WCDMA system.
Li, K., Sandrasegaran, K. & Huang, X. 2005, 'Identity management in vertical handovers for UMTS-WLAN networks', Proceedings of International Conference on Mobile Business (ICMB'05), International Conference on Mobile Business, 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', Proceedings of Third International Conference On Information Technology And Applications, Vol 2, International Conference on Information Technology and Applications, 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', Proceedings of International Conference on Mobile Business (ICMB'05), International Conference on Mobile Business, 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', Proceedings of International Conference on Mobile Business (ICMB'05), International Conference on Mobile Business, IEEE, Sydney, Australia, 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, K. & Sandrasegaran, K. 2005, 'Network Management Challenges for Next Generation Networks', Proceedings of IEEE Conference on Local Computer Networks (LCN), IEEE Conference on Local Computer Networks, IEEE LCN 2005, Sydney, Australia, pp. 593-599.
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Generally, current network management technologies follow two approaches: ITU-Ts recommendations for Telecommunication Management Network (TMN) and IETFs 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. & Li, K. 2005, 'Federated Authentication in Next Generation Wireless Networks', Proceedings of 8th International Symposium on DSP and Communication Systems (DSPCS), 8th International Symposium on DSP and Communication Systems (DSPCS), IEEE DSPC 2005, Noosa Heads, Australia, pp. 1-6.
Sandrasegaran, K. 2007, 'Federated Authentication in Next-Generation Wireless Networks', The 8th International Symposium on DSP and Communication Systems DSPCS, International Symposium on DSP and Communication Systems DSPCS, DSPCS, Noosa Heads, Queenland.
Sandrasegaran, K., Pillay, K. & Tsang, P. 2004, 'Forecasting the Growth of GSM Networks in Australia Using Regression Analysis', Proceedings The 3rd Workshop on Internet, Telecommunications and Signal Processing WITSP'2004, IEEE The 3rd Workshop on Internet, Telecommuications and Signal Processing, 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', Proceedings of the 6th International Conference on Advanced Communication Technology Vol 1, International Conference on Advanced Communication Technology, National Computerization Agency, Phoenix Park, 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.
Shalak, R., Sandrasegaran, K., Agbinya, J. & Subenthiran, S. 2004, 'UMTS core network planning model and comparison of vendor product performance', 6th International Conference on Advanced Communication Technology: Broadband Convergence Network Infrastructure, pp. 685-689.
Third Generation mobile networks are currently being deployed worldwide. For the service provider, upgrading from their existing second generation network or deploying a new third generation network brings with it many considerations which will prove vital to their ultimate success. In these formative years, perhaps the most contentious issue is UMTS network planning and optimisation. In this article, planning considerations are discussed for the core network. A model is generated and proposals are made on how the operator can maximise efficiency as well as provide the user with the required QoS.
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', Proceedings of the Australian Telecommunication Networks and Applications Conference (ATNAC'03), Australian Telecommunication Networks and Applications Conference, Australian Telecommunications CRC, Melbourne, Australia, pp. 1-5.
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Sandrasegaran, K. 1996, 'Simulated training environments for diagnostic tasks', IEEE AFRICON Conference, pp. 982-987.
Technical professionals perform diagnostic activities on a daily basis. However, the task of diagnosis does not form part of the curricula of most institutions. Computer based simulated training environments for diagnostic tasks can fill the gap between educational institutions and field work. This paper presents the motivation, functionality, architecture and design issues for such a training environment.
Sandrasegaran, K. & Appiah, R.K. 1996, 'Engineering education: How can computers help?', IEEE AFRICON Conference, pp. 366-370.
This paper presents the motivation, evolution, successes and benefits of Computer-Assisted Learning (CAL), and describes the techniques and tools available for building CAL software for engineering education. The lessons that have been learnt so far in our work are discussed. It concludes by looking at future work.
Daeinabi, A. & Daeinabi, A. 2014, 'Dynamic Almost Blank Subframe Scheme for Enhanced Intercell Interference Coordination in LTE-A Heterogeneous Networks', International Conference on Communications and Electronics (ICCE), IEEE, Da Nang, Vietnam.
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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 resulting from nodes with different transmission powers, cell range expansion (CRE) technique has been proposed as a cell selection technique. 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 cell throughput and user throughput can be improved using the proposed dynamic ABS scheme.

Journal articles

Huang, K., Kong, X. & Sandrasegaran 2016, 'Modelling Software Corrective Maintenance Productivity Using an Analytical Economic Model and Simulation', International Journal of Computer Applications in Technology.
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In this paper an economic productivity model for software corrective maintenance process is presented. The productivity is analytically modelled using economic value of the maintenance process as the output, and the precommitted fixed cost and variable cost as input. The Analytical Theory of Investment is used to model the relationship of the economic value and these cost components. The values of corrective software maintenance process are analysed. A simulation approach is investigated to analyse the influences to the productivity in software corrective maintenance. This simulation approach provided a tool to identify and analyze the optimal parameters in productivity using the economic model.
Lam, S. & Sandrasegaran 2016, 'Analytical Coverage Probability of a Typical User In Heterogeneous Cellular Networks', Journal of Networks, vol. 11, no. 2, pp. 56-61.
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In a Poisson Point Process (PPP) network model, in which the locations of Base Stations (BSs) are randomly distributed according to a Spatial Poisson Process, has been recently used as a tractable stochastic model to analyse the performance of downlink Heterogeneous Cellular Networks (HCNs). The HCN is modelled as a multi-tier cellular network where each tier is characterised by the transmission power level, propagation path loss exponent and density of BSs. The current works on HCN enabling Intercell Interference Coordination (ICIC) technique usually deal with Strict Frequency Reuse (FR) or Soft FR with a reuse factor of = 1 in a Rayleigh fading channel. It has been assumed that all Base Stations (BSs) transmit continuously which leads to a reduction on the impact of number of users and RBs on network performance. In this paper, the performance of Soft FR with a reuse factor of > 1 in Rayleigh-Lognormal fading channel is evaluated. The impact of the number of users and Resource Blocks (RBs) on Intercell Interference (ICI) are presented for Round Robin scheduling and indicator functions. The results show that there are opposite trends between coverage probability of Cell-Center User (CCU) and Cell-Edge User (CEU).
Thanh, N.H., Tung, D.V., Thu, N.Q., Nam, N.C. & Sandrasegaran, K. 2016, 'Joint scheduling and mapping in support of downlink fairness and spectral efficiency in IEEE 802.16e OFDMA system', International Journal of Communication Systems, pp. n/a-n/a.
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The next generation broadband wireless networks deploy orthogonal frequency division multiple access (OFDMA) as the enabling technologies for broadband data transmission with QoS capabilities. In such broadband wireless systems, one major issue is how to utilize radio resource efficiently while maintaining fairness between sessions as well as providing adequate QoS. In this work, we propose an approach for OFDMA/time division duplex (TDD) downlink suitable for IEEE802.16e WiMAX systems that combines scheduling and burst mapping algorithms for a trade-off between session fairness, QoS, and spectral efficiency. While optimizing radio resources under QoS and fairness constraints is an NP-hard problem, we follow a heuristic approach that simplifies the complexity of the algorithm. Performance results show that while the new scheme outperforms the Proportional Fair algorithm in terms of fairness, it also improves the overall system spectral efficiency. Copyright © 2016 John Wiley & Sons, Ltd. Received 28 April 2015; Revised 14 March 2016; Accepted 15 March 2016 KEY WORDS: OFDMA; scheduling; mapping; radio resource management; fairness; spectral efficiency
Peng, Y.-.J., Dong, Y.-.N., Sandrasegaran, K. & Liu, C. 2015, 'A multimedia transmission control algorithm based on cross-layer design in UMTS networks', Wireless Networks, vol. 21, no. 3, pp. 949-961.
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The performance in the air interface of 3G/UMTS (Universal Mobile Telecommunications System) network is enhanced by the introduction of many advanced functionalities including ARQ (Automatic Repeat Request), HARQ (Hybrid ARQ) and AMC (Adaptive Modulation and Coding). Most existing TFRC (TCP-Friendly Rate Control)-based algorithms designed for wired-wireless heterogeneous networks fail to adapt to these advanced functionalities which results in degradation of performance. This paper proposes a novel cross-layer streaming transmission control algorithm WATC (Wireless-loss Aware Transmission Control) which makes use of the ARQ information to estimate the quality of wireless channels and improve the measurement of delay with the help of RLC (Radio Link Control) sublayer. WATC distinguishes wireless loss from congestion loss by the estimation of the quality of wireless channel and adjusts the sending rate according to the quality of wireless links and the tendency of delay variation. Simulation results show that WATC outperforms existing TFRC-like schemes in terms of loss rate control and throughput, while maintaining high throughput and fairness in multi-flow scenarios.
Afroz, F., Sandrasegaran, K. & H, A.K. 2015, 'Interference Management in Lte Downlink Networks', International Journal of Wireless & Mobile Networks, vol. 7, no. 1, pp. 91-106.
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Heidari, R., Afroz, F., Subramanian, R., Cong, S., Sandrasegaran, K. & Kong, X. 2015, 'Packet Scheduling Study for Heterogeneous Traffic in Downlink 3GPP LTE System', International Journal of Wireless & Mobile Networks, vol. 7, no. 5, pp. 91-106.
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Long Term Evolution (LTE) network deploys Orthogonal Frequency Division Multiple Access (OFDMA) technology for downlink multi-carrier transmission. To meet the Quality of Service (QoS) requirements for LTE networks, packet scheduling has been employed. Packet scheduling determines when and how the user's packets are transmitted to the receiver. Therefore effective design of packet scheduling algorithm is an important discussion. The aims of packet scheduling are maximizing system throughput, guaranteeing fairness among users, andminimizing either or both PacketLoss Ratio (PLR)and packet delay. Inthis paper, the performance of two packet scheduling algorithms namely Log Maximum-Largest Weighted Delay First (LOG-MLWDF) and Max Delay Unit (MDU), developed for OFDM(Orthogonal Frequency Division Multiplexing)networks, has been investigated in LTE downlink networks, and acomparison of those algorithmswith a well-known scheduling algorithm namely Maximum-Largest Weighted Delay First(MLWDF) has been studied.The performance evaluation was in terms of system throughput, PLR and fairness index. This study was performed forboth real time (voice and video streaming)and non-real time (best effort)perspectives. Results show that for streaming flows,LOG-MLWDF shows best PLR performance among the considered scheduling schemes, and for best effort flows, it outperforms theother two algorithms in terms of packet delay and throughput.
Afroz, F., Heidari, R., Shehab, M., Sandrasegaran, K. & Sultana Shompa, S. 2015, 'Comparative Analysis of Downlink Packet Scheduling Algorithms in 3GPP LTE Networks', International Journal of Wireless & Mobile Networks, vol. 7, no. 5, pp. 1-21.
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Long Term Evolution (LTE) mobile network aims to support high speed network services even in highmobility scenarios. To achieve this goal, LTE adopts some advanced features in Radio Resource Management (RRM) procedures. Among them, LTE packet scheduling plays a fundamental role in maximising system performance. In this paper, a comparative analysis on the performances of Proportional Fair (PF), Exponential/Proportional Fair (EXP/PF), Exponential (EXP) Rule, MaximumLargest Weighted Delay First (M-LWDF), Logarithmic (LOG) Rule and Frame Level Scheduler (FLS) LTE downlink packet scheduling algorithms is reported. Performance is evaluated in single cell with interference environment while increasing user number and user speed. Results show that for multimedia flow, FLS scheme outperforms other five schemes in terms of packet delay, packet loss ratio, and average throughput, whereas for best-effort flow, EXP-PF scheme shows better average throughput performance on average as compared with other algorithms being considered herein.
Subramanian, R., Heidari, R. & Sandrasegaran, K. 2015, 'Interoperability and Quality Assurance for Multi-Vendor LTE Network', International Journal of Wireless and Mobile Networks, vol. 7, no. 5, pp. 65-76.
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The deployment of the LTE is picking up pace in many countries and these networks are deployed alongside the existing 2G/3G services. LTE/LTE-A networks offer higher data rates and reduced delay to the subscribers. Today's mobile networks consist of equipment from multiple vendors and they are called multiple vendor networks. Interoperability testing is important at initial network launch and during network expansion. This paper discusses a typical problem related to interoperability testing along with the test results and the issues faced during the testing. The test results discussed in the paper are obtained from three scenarios - before testing, during testing and after testing. The test results are used to study the impact on network performance. Apart from the interoperability testing, an outline of testing that focus on general network stability, the interworking capability of LTE with other technologies such as 2G and 3G and taxonomy for the generation of key performance indicators (KPIs) are also discussed.
Subramanian, R., Heidari, R., Sandrasegaran, K., Dhanraj, A.M.A. & Karthik, S. 2015, 'Benchmarking of Cell Throughput Using Proportional Fair Scheduler in a Single Cell Environment', International Journal of Wireless & Mobile Networks, vol. 7, no. 2, pp. 67-79.
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The proportional fair (PF) scheduling algorithm compromises between cell throughput and fairness. Many research findings have been published by various researchers about PF algorithm based on mathematical model and simulations. In this paper we have taken the practical route to analyse the algorithm based on three types of subscription. In this benchmarking study, the user subscriptions are differentiated as Gold, Silver and Bronze schemes and they are provisioned with certain throughputs. Apart from subscriptions plans, the channel condition also plays a major role in determining the throughput. So in order to ensure fairness among different subscriptions even in the bad channel conditions and to deliver the provisioned throughputs certain priorities are attached with the subscriptions. As per the subscription plans Gold subscribers are assigned with 50% of the speed offered by the network as maximum based on CAT3 speed (100 Mbps in DL and 50 Mbps in UL), Silver is assigned with 25% of the max speed and Bronze is assigned with 12% of the max speed. The priorities assigned to subscribers determines the fairness in the unfavourable channel conditions - Bronze (high), Silver and Gold (medium). In this paper, an benchmarking tests have been performed with all of three types of subscribers for nearly two hours in the live single cell network without any heterogeneous cells influencing it. Furthermore, the results are compared with the simulation results.
Afroz, F., Subramanian, R., Heidary, R., Sandrasegaran, K. & Ahmed, S. 2015, 'SINR, RSRP, RSSI and RSRQ Measurements in Long Term Evolution Networks', International Journal of Wireless & Mobile Networks, vol. 7, no. 4, pp. 113-123.
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Subramanian, R., Ghosal, P., Barua, S., Xing, S., Cong, S.L., Al Kim, H. & Sandrasegaran, K. 2015, 'Survey of LTE Downlink Schedulers Algorithms in Open Access Simulation Tools NS-3 and LTE-SIM', International Journal of Wireless & Mobile Networks, vol. 7, no. 2, pp. 1-16.
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The LTE/LTE-A has become a catchphrase for research and lot of research are being conducted and carried out in LTE in various issues by various people. New tools are developed and introduced in the market to interpret the results of the new algorithms proposed by various people. Some tools are open access which are free to use but some tools are produced by the companies which are not open access. In this paper some of the open access simulation tools like LTE-Sim and NS-3 are analyzed and LTE downlink scheduler algorithms are simulated using those tools. In LTE systems, the downlink scheduler is an important component for radio resource management; hence in the context of LTE simulation, a study between the downlink scheduler models between the simulators are performed.
Afroz, F., Huq, A., F, A. & Sandrasegaran, K. 2015, 'Performance Analysis of Adaptive Noise Canceller Employing NLMS Algorithm', International Journal of Wireless & Mobile Networks, vol. 7, no. 2, pp. 45-58.
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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.
Kim, H.A., Barua, S., Ghosal, P. & Sandrasegaran, K. 2014, 'Macro with Pico Cells (HetNets) System Behavior Using Well-known scheduling Algorithms', Figures, International Journal of Wireless & Mobile Networks (IJWMN), vol. 6, no. 5, pp. 109-122.
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This paper demonstrates the concept of using Heterogeneous networks (HetNets) to improve Long Term Evolution (LTE) system by introducing the LTE Advance (LTE-A). The type of HetNets that has been chosen for this study is Macro with Pico cells. Comparing the system performance with and without Pico cells has clearly illustrated using three well-known scheduling algorithms (Proportional Fair PF, Maximum Largest Weighted Delay First MLWDF and Exponential/Proportional Fair EXP/PF). The system is judged based on throughput, Packet Loss Ratio PLR, delay and fairness.A simulation platform called LTE-Sim has been used to collect the data and produce the paper outcomes and graphs. The results prove that adding Pico cells enhances the overall system performance. From the simulation outcomes, the overall system performance is as follows: throughput is duplicated or tripled based on the number of users, the PLR is almost quartered, the delay is nearly reduced ten times (PF case) and changed to be a half (MLWDF/EXP cases), and the fairness stays closer to value of 1. It is considered an efficient and cost effective way to increase the throughput, coverage and reduce the latency.
Ghosal, P., Barua, S., Subramanian, R., Xing, S. & Sandrasegaran, K. 2014, 'A novel approach for mobility management inf lte femtocells', International Journal of Wireless & Mobile Networks(IJWMN), vol. 6, no. 5, pp. 45-58.
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LTE is an emerging wireless data communication technology to provide broadband ubiquitous Internet access. Femtocells are included in 3GPP since Release 8 to enhance the indoor network coverage and capacity. The main challenge of mobility management in hierarchical LTE structure is to guarantee efficient handover to or from/to/between Femtocells. This paper focuses, on different types of Handover and comparison performance between different decision algorithms. Furthermore, a speed based Handover algorithm for macro-femto scenario is proposed with simulation results
Barua, S., Afroz, F., Sunbeam Islam, S., Ahmed, A.U., Ghosal, P. & Sandrasegaran, K. 2014, 'Comparative Study on Priority Based QOS Aware Mac Protocols for WSN', International Journal of Wireless & Mobile Networks, vol. 6, no. 5, pp. 175-181.
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Xing, S., Ghosal, P., Barua, S., Subramanian, R. & Sandrasegaran, K. 2014, 'System Level Simulation for Two Tier Macro-Femto Cellular Networks', International Journal of Wireless & Mobile Networks, vol. 6, no. 6, pp. 01-14.
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Subramanian, R., Barua, S., Cong Lam, S., Ghosal, P. & Sandrasegaran, K. 2014, 'Group Based Algorithm to Manage Access Technique in the Vehicular Networking to Reduce Preamble ID Collision and Improve RACH allocation in ITS', International Journal of Wireless & Mobile Networks, vol. 6, no. 5, pp. 1-15.
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Afroz, F., Barua, S. & Sandrasegaran, K. 2014, 'Performance Analysis of FLS, EXP, LOG and M-LWDF Packet Scheduling Algorithms in Downlink 3GPP LTE System', International Journal of Wireless & Mobile Networks, vol. 6, no. 5, pp. 77-91.
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Subramanian, R. & Sandrasegaran, K. 2014, 'Rach Congestion in Vehicular Networking', International Journal of Wireless & Mobile Networks, vol. 6, no. 5, pp. 153-164.
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Ramli, H.A.M., Sandrasegaran, K., Ismail, A.F., Latif, S.A. & Isa, F.N.M. 2014, 'A simulation tool for downlink long term evolution-advanced', Research Journal of Applied Sciences, Engineering and Technology, vol. 8, no. 19, pp. 2032-2041.
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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.
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, '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, K., Sandrasegaran, K. & Tung, T.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 JournalWireless Personal Communications PublisherSpringer Netherlands ISSN0929-6212 (Print) 1572-834X (Online) IssueVolume 52, Number 3 / February, 2010 DOI10.1007/s11277-008-9634-7 Pages477-499 Subject CollectionEngineering SpringerLink DateFriday, 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.
Li, K. & 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.
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.
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.
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.
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.
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.
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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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.
Sandrasegaran, K. & Prag, K. 1999, 'Planning point-to-multipoint rural radio access networks using expert systems', Expert Systems with Applications, vol. 17, no. 3, pp. 145-166.
The goal of this research work was to explore the rural telecommunications environment and develop software to automate the planning of wireless access networks in rural areas. This paper presents the application of an expert system for the planning of point-to-multipoint radio access networks. The system was developed using the C Language Integrated Production System environment. It uses the object oriented and rule-based paradigms for knowledge representation and the planning process. © 1999 Elsevier Science Ltd. All rights reserved.
Venayagamoorthy, G.K., Moonasar, V. & Sandrasegaran, K. 1998, 'Voice recognition using neural networks', Proceedings of the South African Symposium on Communications and Signal Processing, COMSIG, pp. 29-32.
One solution to the crime and illegal immigration problem facing South Africa is the use of biometrics techniques and technology. Biometrics are methods for recognizing a user based on unique physiological and/or behavioural characteristics of the user. This paper presents the results of an ongoing work in using neural networks for voice recognition.
Niaz, S.K., Sandrasegaran, K., Renny, F.H. & Jones, B.J. 1997, 'Postinfective diarrhoea and bile acid malabsorption.', Journal of the Royal College of Physicians of London, vol. 31, no. 1, pp. 53-56.
Postinfective irritable bowel syndrome with diarrhoea and idiopathic bile acid malabsorption remains an enigma. We examined the records of 84 patients whose 75SeHCAT scans were indicative of bile acid malabsorption (< 15% one week retention). Identifiable causes of bile acid malabsorption were: previous ileal surgery (7), Crohn's disease (22), radiation enteritis (13), vagotomy, gastrectomy or cholecystectomy (10) and miscellaneous (3). Sixteen of 29 patients with apparently idiopathic bile acid malabsorption gave a clear history of acute gastroenteritis before the onset of chronic diarrhoea lasting from 0.25-18 years until their positive 75SeHCAT scan. Only four cases of campylobacter, and one each of shigella and salmonella were documented. Extensive investigation failed to detect other possible pathologies. In response to bile acid sequestrants, mean stool frequency fell from 7.2 per day to 2.1 per day (p < 0.001). We have observed that postinfective chronic diarrhoea is associated with chronic bile acid malabsorption, which can be successfully treated with bile acid sequestrants such as cholestyramine.

Reports

Sandrasegaran, K. Alcatel 2006, Models of Digital Identity in Next Generation Networks, Australia.
Sandrasegaran, K. Alcatel 2005, Digital Identity in Next Generation Networks, Australia.
Sandrasegaran, K. Alcatel 2005, Identity Management in Next Generation Networks, Australia.

City of Sydney, Water Research Australia, NOKIA, Alcatel-Lucent, Ecoseal Pty Ltd. 

Visiting Lecturer at Chulalongkorn University.