Abstract：

Cognitive radio is an emerging technology to support dynamic spectrum access, thus to solve the challenging problem of radio spectrum scarcity. In cognitive radio networks, the secondary network (users) are allowed to utilize the frequency bands of primary network (users) when they are not currently being used. To support this function, the secondary users are required to sense the radio frequency environment, and once the primary users are found to be active, the secondary users have to vacate the channel within certain amount of time.  

In this talk, I will first give an overview on the current research in cognitive radio networks. Then I will focus on the design of spectrum sensing schemes to detect the presence of primary users. Finally, I will present the fundamental tradeoff between sensing capability and achievable throughput of the secondary users. In particular, we consider the design of sensing slot duration to maximize the achievable throughput for the secondary users under the constraint that the primary users are sufficiently protected. The derived results provide the guideline for the cognitive MAC design.

Biographical information：

Dr. Ying-Chang Liang received PhD degree in Electrical Engineering in 1993. He is now Senior Scientist in the Institute for Infocomm Research (I2R), Singapore, where he has been leading the research activities in the area of cognitive radio and cooperative communications and the standardization activities in IEEE 802.22 wireless regional networks (WRAN) for which his team has made fundamental contributions in physical layer, MAC layer and spectrum sensing solutions. He also holds adjunct associate professorship positions in Nanyang Technological University (NTU) and National University of Singapore (NUS), both in Singapore, and adjunct professorship position with University of Electronic Science & Technology of China (UESTC). He has been teaching graduate courses in NUS since 2004. From Dec 2002 to Dec 2003, Dr. Liang was a visiting scholar with the Department of Electrical Engineering, Stanford University. His research interest includes cognitive radio, dynamic spectrum access, reconfigurable signal processing for broadband communications, space-time wireless communications, wireless networking, information theory and statistical signal processing. 

Dr. Liang is now an Associate Editor of IEEE Transactions on Vehicular Technology. He was an Associate Editor of IEEE Transactions on Wireless Communications from 2002 to 2005, Lead Guest-Editor of IEEE Journal on Selected Areas in Communications, Special Issue on Cognitive Radio: Theory and Applications, and Guest-Editor of COMPUTER NETWORKS Journal (Elsevier) Special Issue on Cognitive Wireless Networks. He received the Best Paper Awards from IEEE VTC-Fall'1999 and IEEE PIMRC'2005, and 2007 Institute of Engineers Singapore (IES) Prestigious Engineering Achievement Award. Dr. Liang has served for various IEEE conferences as technical program committee (TPC) member. He was Publication Chair of 2001 IEEE Workshop on Statistical Signal Processing, TPC Co-Chair of 2006 IEEE International Conference on Communication Systems (ICCS'2006), Panel Co-Chair of 2008 IEEE Vehicular Technology Conference Spring (VTC'2008-Spring), TPC Co-Chair of 3rd International Conference on Cognitive Radio Oriented Wireless Networks and Communications (CrownCom'2008), Deputy Chair of 2008 IEEE Symposium on New Frontiers in Dynamic Spectrum Access Networks (DySPAN'2008), and Co-Chair, Thematic Program on Random matrix  theory and its applications in statistics and  wireless communications, Institute for Mathematical Sciences, National University of Singapore, 2006. Dr. Liang is a Senior Member of IEEE. He holds six granted patents and more than 15 filed patents.