Title: Rethink Coexisting Issues of Small Cells and Macrocells: Spectrum Sharing and Traffic Requirement Perspectives

Speaker: Li-Chun Wang

Abstract:

Multi-tier cellular architectures are important for enhancing coverage and capacity performance in wireless systems. According to the current system deployment methodology, macrocells aim for providing symmetric voice traffic. As a result, most macrocellular systems adopt frequency division duplex (FDD) for providing symmetric traffic, where two equal-bandwidth spectra are allocated for uplink and downlink transmissions, respectively.

On the other hand, small cells are deployed mainly for capacity-hungry data services, which are asymmetric data traffic. If small cells still adopt FDD for asymmetric data traffic, it seems to be an inappropriate design from the aspect of traffic requirement. A time division duplex (TDD) system requires only single frequency band and can change the uplink and downlink ratio more flexible than a FDD system. Thus TDD is very suitable in providing asymmetric traffic. One interesting question arises: Can TDD small cells coexist with FDD macrocells by sharing the same spectrum? If so, how the interference is handled in such a FDD/TDD coexisting system?

In this talk, we will discuss potential interference mitigation techniques for the FDD/TDD coexisting system. Last, we will discuss other frequency sharing concepts, such as the single-frequency full duplex systems and LTE-unlicensed.

Bio:

Li-Chun Wang (M'96 -- SM'06 -- F'11) received the B.S. degree from National Chiao Tung University, Taiwan, R. O. C. in 1986, the M.S. degree from National Taiwan University in 1988, and the Ms. Sci. and Ph. D. degrees from the Georgia Institute of Technology , Atlanta, in 1995, and 1996, respectively, all in electrical engineering.

From 1990 to 1992, he was with the Telecommunications Laboratories of Chunghwa Telecom Co. In 1995, he was affiliated with Bell Northern Research of Northern Telecom, Inc., Richardson, TX. From 1996 to 2000, he was with AT&T Laboratories, where he was a Senior Technical Staff Member in the Wireless Communications Research Department. Since August 2000, he has joined the Department of Electrical and Computer Engineering of National Chiao Tung University in Taiwan and is the current Chairman of the same department. His current research interests are in the areas of radio resource management and cross-layer optimization techniques for wireless systems, heterogeneous wireless network design, and cloud computing for mobile applications.

Dr. Wang won the Distinguished Research Award of National Science Council, Taiwan in 2012, and was elected to the IEEE Fellow grade in 2011 for his contributions to cellular architectures and radio resource management in wireless networks. He was a co-recipient(with Gordon L. Stuber and Chin-Tau Lea) of the 1997 IEEE Jack Neubauer Best Paper Award for his paper "Architecture Design, Frequency Planning, and Performance Analysis for a Microcell/Macrocell Overlaying System," IEEE Transactions on Vehicular Technology, vol. 46, no. 4, pp. 836-848, 1997. He has published over 200 journal and international conference papers. He served as an Associate Editor for the IEEE Trans. on Wireless Communications from 2001 to 2005, the Guest Editor of Special Issue on "Mobile Computing and Networking" for IEEE Journal on Selected Areas in Communications in 2005, "Radio Resource Management and Protocol Engineering in Future Broadband Networks" for IEEE Wireless Communications Magazine in 2006, and “Networking Challenges in Cloud Computing Systems and Applications,” for IEEE Journal on Selected Areas in Communications in 2013, respectively. He is holding 10 US patents.