Distributed Low-Complexity Multi-Cell Coordinated Multicast Beamforming with Large-Scale Antennas

We consider downlink multicast beamforming in a multi-cell network with large-scale antennas. To reduce both communication and computation complexity in coordinated multicast beamforming, we propose the signal-to-leakage ratio (SLR) based coordinated multicast beamforming design to maximize the minimum SLR in the network. The SLR metric allows coordinated beamforming to be computed distributively and independently at each BS. To further reduce the complexity in obtaining the beam solution, we consider weighted maximum ratio transmission beamforming structure which transforms the multicast beamforming optimization into a weight optimization problem which is solved by the semi-definite relaxation approach. Our proposed distributed solution requires no communication or information sharing among cells and has very low computational complexity not depending on the number of antennas. Simulation shows that our proposed solution results in only a small loss to the centralized coordinated beamforming solution, but is significantly better than the non-coordinated methods.