The distributed antenna system (DAS) has become a promising candidate for next-generation (5G) mobile communication systems. In DASs, many remote antenna ports are geographically distributed over a large area and connected to a central processor by fiber or coaxial cable. Although the idea of DAS was originally proposed to cover the dead spots in indoor wireless communication systems, research activities on cellular DASs have been intensified in the past few years owing to the fast growing demand for high data-rate services.
For cellular systems, the use of distributed base-station (BS) antennas enables efficient utilization of spatial resources, which, on the other hand, also significantly complicates the channel modeling and performance analysis. In this talk, I will introduce my recent work on the uplink capacity analysis of large-scale cellular DASs. I will start from the single-cell multi-user system, and address a series of fundamental questions such as how the uplink sum capacity varies with the BS antenna layout and key parameters including the availability of channel state information at the transmitter (CSIT) and the number of BS antennas. For the multi-cell case, I will show that with distributed BS antennas, despite substantial gains on the uplink sum capacity owing to the reduction of the inter-cell interference level, the cell-edge problem could be exacerbated. To demonstrate that the performance disparity originates from the cellular structure rather than the BS antenna layout, I will further introduce the concept of "virtual cell" and show that a uniform inter-cell interference density can be achieved in a DAS if each user chooses a few surrounding BS antennas to form its virtual cell. By doing so, each BS antenna serves a declining number of users as the density of BS antennas increases, indicating good scalability that is much appreciated in a large-scale network. I will conclude the talk by discussing the implications to cutting-edge cellular technologies such as small cells and pCell.
Dr. Lin Dai received her Ph. D. degree from Tsinghua University in 2003. She was a postdoctoral fellow at the Hong Kong University of Science and Technology and University of Delaware. Since 2007, she has been with City University of Hong Kong, where she is an associate professor. She has broad research interests in wireless communications and networking theory. She was a co-recipient of the Best Paper Award at IEEE WCNC 2007 and the IEEE Marconi Prize Paper Award in 2009.