Energy-efficient coordinated beamforming in downlink OFDMA cellular networks

This work addresses the problem of coordinated beamforming in the downlink of an OFDMA cellular network. The figure of merit to be optimized is the global energy efficiency, defined as the ratio between the sum-rate of the coordinated base stations and the corresponding power consumption, under a per-base-station power constraint. The Karush-Kuhn-Tucker (KKT) conditions of the considered optimization problem are first derived to gain insights into the structure of the optimal beamformers. Then, a suboptimal design procedure based on the KKT conditions is proposed and analyzed.