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University:	Auburn University, Auburn
Professor:	Shiwen Mao
Department:	Department of Electrical and Computer Engineering
Student:	Donglin Hu, Jing Ning

Research on Cognitive Radio Networks

• We investigate the challenging problem of enabling multicast video service in emerging cognitive radio (CR) networks. We propose a cross-layer optimization approach to multicast video in CR networks. Specifically, we model CR video multicast as an optimization problem, while considering important design factors including scalable video coding, video rate control, spectrum sensing, dynamic spectrum access, modulation, scheduling, retransmission, and primary user protection. The objective is to optimize the overall received video quality as well as achieving proportional fairness among multicast users, while keeping the interference to primary users below a prescribed threshold. Although the problem can be solved using advanced optimization techniques, we propose a sequential fixing algorithm and a greedy algorithm with low complexity and proven optimality gap. Our simulations using MPEG-4 fine grained scalability (FGS) demonstrate the efficacy and superior performance of the proposed approach as compared with an alternative equal allocation scheme.

• We will also look into the problem of more efficient medium access control for cognitive radio networks, incorporating maximum weight matching-based scheduling algorithms with spectrum sensing and opportunistic spectrum access, to fully explore the spectrum available in such networks while under the constraints of primary user protection.

Research on Wi-Fi Mesh Networks

• We plan to use OPNET Model to evaluate the performance of a Wi-Fi mesh network for delivering bursty data. We will evaluate various routing strategies, including single path routing (e.g., using AODV), multi-path routing, and network coding that does not need any routing information. We also plan to evaluate the performance of the above strategies under various jamming scenarios. Performance metrices such as throughput, delay, jitter and control overhead will be used in the evaluation.

Research on Microwave Back Haul

• We plan to conduct a modeling and simulation study of a microwave backbone wireless network using OPNET modeler. Microwave backhaul is one of the latest mega trends in the carrier and enterprise sectors. Microwave is a viable option from a cost and ownership perspective due to technology in-novation over the past several years. We plan to develop or adapt the microswave propagation model, simulate the performance of point-to-point transmissions, and finally simulation a microwave back haul network that connecting multiple access networks to the Internet with multiple gigabits per second capacity.

Acknowledgment: