Ergodic Throughput in Coordinated Multi-Point Downlink Under Distributed Power Constraints
Coordinated multi-point systems comprise distributed access points (APs) serving a common downlink user. Although the transmissions here are centrally coordinated, the non-colocated APs may have to respect different power constraints, thus necessitating novel power control and beamforming solutions. Numerical solutions that maximize the throughput of a fixed fading matrix under diverse distributed power constraints have appeared in the recent past. However, the time varying fading model where each AP adapts its transmit power and beamforming vector based on the channel matrix, in order to maximize the ergodic throughput, has received much less attention. Note that here each AP should respect its own specified long-term average power constraint. This paper proposes novel power control and beamforming solutions that not only respect the distributed power constraints but also achieve near-optimal ergodic throughput in popular fading models.