内容摘要：

The increasing complexity of communication networks in size and density provides us enormous opportunities to exploit interaction among multiple nodes, to achieve date throughput. On the flip side, however, there are significant challenges in managing interference that multiple source-destination pairs in the network may cause to each other. In this talk, we present some recent advances in information theory on how to exploit the opportunities, as well as how to overcome the challenges for various networks. These theoretically results provide potential guidance on possible ways of increasing spectral efficiency for future wireless systems. 

In particular, we first present results on the impact of feedback and cooperation on networks with multiple-antenna transceivers. We find that feedback-one of the common ways to enable interaction in networks-has a promising role in improving the capacity of interference networks. Specifically, in stark contrast to the point-to-point case, a limited feedback can improve the capacity of interference-limited networks and the improvement can be unbounded.  We then present results on several two-way relay networks.Two-way relay is potentially an effective approach to spectrum sharing and aggregation by allowing simultaneous bidirectional transmissions between source-destinations pairs. For the two-way 2×2×2 relay network, where there are four source/destination nodes and two relay nodes, with each source sending a message to its destination, we show that without relay caching the total degrees of freedom (DoF) is bounded from above by 8/3, indicating that bidirectional links do not double the DoF (It is known that the total DoF of one-way 2 × 2 × 2 relay network is 2.). Further, we show that the DoF of 8/3 is achievable for the two-way 2 × 2 × 2 relay network with relay caching, indicating caching can potentially increase the DoF. Results on two-way bufferfly networks  will also be presented.

主讲人简介：

Xiaodong Wang received the Ph.D degree in Electrical Engineeringfrom Princeton University. He is a Professor of Electrical Engineering at ColumbiaUniversity in New York.Dr. Wang’s research interests fall in the general areas of signal processing and communications, and has published extensively in these areas. Among his publications is a book entitled “Wireless Communication Systems: Advanced Techniques for Signal Reception”, published by Prentice Hall in 2003. His current research interests include wireless communications, statistical signal processing, and genomic signal processing. Dr. Wang received the 1999 NSF CAREER Award, the 2001 IEEE Communications Society and Information Theory Society Joint Paper Award, and the 2011 IEEE Communication Society Award for Outstanding Paper on New Communication Topics. He has served as an Associate Editor for the IEEE Transactions on Communications, the IEEE Transactions on Wireless Communications, the IEEE Transactions on Signal Processing, and the IEEE Transactions on Information Theory. He is a Fellow of the IEEE and listed as an ISI Highly-cited Author.