The 18th Annual IEEE International Symposium on Personal, Indoor and Mobile Radio Communications (PIMRC’07) LIMITED DOWNLINK NETWORK COORDINATION IN CELLULAR NETWORKS

We investigate the downlink throughput of cellular systems where groups of M antennas – either co-located or spatially distributed – transmit to a subset of a total population of K> M users in a coherent, coordinated fashion in order to miti-gate intercell interference. We consider two types of coordi-nation: the capacity-achieving technique based on dirty paper coding (DPC), and a simpler technique based on zero-forcing (ZF) beamforming with per-antenna power constraints. During a given frame, a scheduler chooses the subset of the K users in order to maximize the weighted sum rate, where the weights are based on the proportional-fair scheduling algorithm. We consider the weighted average sum throughput among K users per cell in a multi-cell network where coordination is limited to a neighborhood of M antennas. Consequently, the perfor-mance of both systems is limited by interference from antennas that are outside of the M coordinated antennas. Compared to a 12-sector baseline which uses the same number of antennas per cell site, the throughput of ZF and DPC achieve respective gains of 1.5 and 1.75.