Bandwidth-guaranteed fair scheduling with effective excess bandwidth allocation for wireless networks

Traffic scheduling is key to the provision of quality of service (QoS) differentiation and guarantees in wireless networks. Unlike its wireline counterpart, wireless communications pose special channel-specific problems such as time-varying link capacities and location-dependent errors. These problems make designing efficient and effective traffic scheduling algorithms for wireless networks very challenging. Although many wireless packet scheduling algorithms have been proposed in recent years, issues such as how to improve bandwidth efficiency and maintain goodput fairness with various link qualities for power-constrained mobile hosts remain unresolved. In this paper, we devise a simple wireless packet scheduling algorithm called bandwidth-guaranteed fair scheduling with effective excess bandwidth allocation (BGFS-EBA), which addresses these issues. Our studies reveal that BGFS-EBA effectively distributes excess bandwidth, strikes a balance between effort-fair and outcome-fair, and provides a delay bound for error-free flows and transmission effort guarantees for error-prone flows. © 2008 IEEE.published_or_final_versio

Intelligent packet discarding policies for real-time traffic over wireless networks.

Yuen Ching Wan.Thesis (M.Phil.)--Chinese University of Hong Kong, 2006.Includes bibliographical references (leaves 77-83).Abstracts in English and Chinese.Abstract --- p.iAcknowledgement --- p.iiiChapter 1 --- Introduction --- p.1Chapter 1.1 --- Nature of Real-Time Traffic --- p.1Chapter 1.2 --- Delay Variability in Wireless Networks --- p.2Chapter 1.2.1 --- Propagation Medium --- p.3Chapter 1.2.2 --- Impacts of Network Designs --- p.5Chapter 1.3 --- The Keys - Packet Lifetime & Channel State --- p.8Chapter 1.4 --- Contributions of the Thesis --- p.8Chapter 1.5 --- Organization of the Thesis --- p.9Chapter 2 --- Background Study --- p.11Chapter 2.1 --- Packet Scheduling --- p.12Chapter 2.2 --- Call Admission Control (CAC) --- p.12Chapter 2.3 --- Active Queue Management (AQM) --- p.13Chapter 2.3.1 --- AQM for Wired Network --- p.14Chapter 2.3.2 --- AQM for Wireless Network --- p.17Chapter 3 --- Intelligent Packet Discarding Policies --- p.21Chapter 3.1 --- Random Packet Discard --- p.22Chapter 3.1.1 --- Variable Buffer Limit (VABL) --- p.22Chapter 3.2 --- Packet Discard on Expiration Likelihood (PEL) --- p.23Chapter 3.2.1 --- Working Principle --- p.24Chapter 3.2.2 --- Channel State Aware Packet Discard on Expiration Likelihood (CAPEL) --- p.26Chapter 3.3 --- System Modeling --- p.29Chapter 3.3.1 --- Wireless Channel as an Markov-Modulated Poisson Process (MMPP) --- p.30Chapter 3.3.2 --- System Analysis --- p.30Chapter 3.3.3 --- System Time Distribution --- p.33Chapter 3.3.4 --- Approximation of System Time Distribution by Gamma Distribution --- p.36Chapter 3.4 --- Goodput Analysis of Intelligent Packet Discarding Policies --- p.38Chapter 3.4.1 --- Variable Buffer Limit (VABL) --- p.38Chapter 3.4.2 --- CAPEL at the End-of-Line --- p.39Chapter 3.4.3 --- CAPEL at the Head-of-Line --- p.43Chapter 4 --- Performance Evaluation --- p.44Chapter 4.1 --- Simulation --- p.44Chapter 4.1.1 --- General Settings --- p.45Chapter 4.1.2 --- Choices of Parameters --- p.46Chapter 4.1.3 --- Variable Buffer Limit (VABL) --- p.49Chapter 4.1.4 --- CAPEL at the End-of-Line --- p.53Chapter 4.1.5 --- CAPEL at the Head-of-Line --- p.60Chapter 4.2 --- General Discussion --- p.64Chapter 4.2.1 --- CAPEL vs RED --- p.64Chapter 4.2.2 --- Gamma Approximation for System Time Distribution . --- p.69Chapter 5 --- Conclusion --- p.70Chapter A --- Equation Derivation --- p.73Chapter A.l --- Steady State Probabilities --- p.73Bibliography --- p.7

Packet scheduling in satellite HSDPA networks.

Thesis (M.Sc.Eng.)-University of KwaZulu-Natal, Durban, 2010.The continuous growth in wireless networks is not showing any sign of slowing down as new services, new technologies and new mobile users continue to emerge. Satellite networks are expected to complement the terrestrial network and be a valid option to provide broadband communications services to both fixed and mobile users in scenarios where terrestrial networks cannot be used due to technical and economical viability. In the current emerging satellite networks, where different users with varying traffic demands ranging from multimedia, voice to data and with limited capacity, Radio Resource Management (RRM) is considered as one of the most significant and challenging aspect needed to provide acceptable quality of service that will meet the requirements of the different mobile users. This dissertation considers Packet Scheduling in the Satellite High Speed Downlink Packet Access (S-HSDPA) network. The main focus of this dissertation is to propose a new cross-layer designed packet scheduling scheme, which is one of the functions of RRM, called Queue Aware Channel Based (QACB) Scheduler. The proposed scheduler, which, attempts to sustain the quality of service requirements of different traffic requests, improves the system performance compared to the existing schedulers. The performance analysis comparison of the throughput, delay and fairness is determined through simulations. These metrics have been chosen they are three major performance indices used in wireless communications. Due to long propagation delay in HSDPA via GEO satellite, there is misalignment between the instantaneous channel condition of the mobile user and the one reported to the base station (Node B) in S-HSDPA. This affects effectiveness of the channel based packet schedulers and leads to either under utilization of resource or loss of packets. Hence, this dissertation investigates the effect of the introduction of a Signal-to-Noise (SNR) Margin which is used to mitigate the effect of the long propagation delay on performance of S-HSDPA, and the appropriate SNR margin to be used to achieve the best performance is determined. This is determined using both a semi-analytical and a simulation approach. The results show that the SNR margin of 1.5 dB produces the best performance. Finally, the dissertation investigates the effect of the different Radio Link Control (RLC) Transmission modes which are Acknowledged Mode (AM) and Unacknowledged Mode (UM) as it affects different traffic types and schedulers in S-HSDPA. Proportional fair (PF) scheduler and our proposed, QACB, scheduler have been considered as the schedulers for this investigation. The results show that traffic types are sensitive to the transmitting RLC modes and that the QACB scheduler provides better performance compared to PF scheduler in the two RLC modes considered