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Energy-efficient Transmissions with Delay Constraints over a Wireless Link

SPEAKER: Mr. Wanshi Chen, Graduate Student, Communication Sciences InstituteABSTRACT: Future wireless networks are anticipated to accommodate diverse applications of various quality-of-service (QoS) requirements with limited system resource. There exists a fundamental trade-off between transmission energy and packet delay. It is of great importance to minimize the total packet transmission energy while satisfying the underlying delay constraints for network life maximization, system throughput maximization, etc. The problem of optimal offline scheduling (vis-a-vis total transmission energy) for a group of packets, each of which is subject to an individual delay constraint, over a fading channel is studied. The offline scheduler, assuming information of all packet arrivals and channel states before scheduling, is formulated as a convex optimization problem with linear constraints. The optimality conditions are analyzed. The properties of the transmission rates under the optimal offline scheduling and the corresponding delay performance are characterized. It is found that when packet sizes and channel coefficients are identically and independently distributed, the optimal transmission rates exhibit a symmetry property. The properties of the optimal offline scheduling and the impact of packet sizes, individual delay constraints, and channel variations are demonstrated via simulations. A heuristic online scheduling algorithm, which utilizes both causal traffic and channel variations, is proposed and compared with the optimal offline scheduling in terms of delay and energy performance via simulations.BIO: Wanshi Chen received a B.S. degree (with highest honors) from Southwest Jiaotong University, Chengdu, China and an M.S. degree from the Ohio State University, Columbus, respectively. He is currently pursuing a Ph.D. degree under the guidance of Prof. Urbashi Mitra. From 2000 to 2006, he was with Ericsson working on CDMA2000 related research, implementation, and standard development. Numerous patents have been filed by him during his stay with Ericsson. Since May 2006, he has been with Qualcomm Corporate R&D, where he is involved in research and development of the long-term evolution of third-generation wireless standards. His research interests include topics in resource allocation, communication theory, cooperative transmissions, and wireless networking.Host: Prof. Urbashi Mitra, ubli@usc.edu

Location: Hughes Aircraft Electrical Engineering Center (EEB) - 248

Audiences: Everyone Is Invited

Contact: Mayumi Thrasher