Topic：Degrees of Freedom of Cached MIMO Relay Networks

Time：2014年12月16日（周二）上午9:30-10:30

Venue：信电大楼, 215学术会议室

Speaker：Vincent Lau, Chair Professor, FIEEE,

       Dept. of ECE, Hong Kong University of Science and Technology

Biography

Vincent obtained B.Eng (Distinction 1st Hons) from the University of Hong Kong (1989-1992) and Ph.D. from the Cambridge University (1995-1997). He completed the Ph.D. degree in two years and joined Bell Labs from 1997-2004. He joined the Department of ECE, Hong Kong University of Science and Technology (HKUST) in 2004 and is currently a Chair Professor and the Founding Director of Huawei-HKUST Joint Innovation Lab at HKUST. He is also elected as IEEE Fellow, HKIE Fellow, Croucher Senior Research Fellow and Changjiang Chair Professor. Vincent has published more than 220 IEEE journal and conference papers and has contributed to 32 US patents on various wireless systems. In addition, he is also the key contributor of four IEEE standard contributions to IEEE 802.22 (WRAN / Cognitive Radio). His current research focus includes robust cross layer optimization for MIMO/OFDM wireless systems, interference mitigation techniques for wireless networks, delay-optimal cross layer optimizations as well as multi-timescale stochastic network optimization. He has obtained three IEEE best paper awards and is currently an area editor of IEEE Transactions on Wireless Communications, area editor of IEEE Signal Processing Letters, EUARSIP Wireless Communications and Networking as well as guest editor of JSAC.

Abstract

Relay can be regarded as a low cost base station without backhaul. There has been a lot of works studying wireless relay channels. However, due to the cut-set bound, no DoF gain in relay is possible and only marginal SNR gain is reported. In this talk, we shall propose a novel “physical layer caching scheme” and study the degree of freedom (DoF) gains in cached MIMO relay networks. While caching has been widely used in conventional content distribution networks or P2P networks, the proposed physical layer caching is very different. In conventional SDN or P2P caching, the benefit of cache is to reduce the number of hops from the source to the consumers. However, in the proposed physical layer caching solution for wireless relay networks, there is a unique and important additional benefit, namely the cache-induced cooperative MIMO gain. Specifically, using physical layer caching, we can dynamically change from an unfavorable PHY topology (such as relay channels) to a more favorable PHY topology (such as MIMO broadcast channels). Hence, physical layer caching can fully unleash the potential benefit of wireless relay and this is very attractive because the cost of harddisk capacity in the cache is much lower than the backhaul capacity.