Energy-efficient multiuser MIMO beamforming

In previous works, MIMO beamforming in multiuser wireless systems is typically formulated in two ways: one is minimizing the total transmit power with individual signal-to-interference-plus-noise ratio (SINR) constraints for each user; and the other one is maximizing the minimum SINR among all the users with a total transmission power constraint. However, although the total transmit power is optimized, these beamforming algorithms might not be the optimum with respect to the individual energy effciency of each user. In this paper, we consider an energy-efficient multiuser MIMO beamforming algorithm that maximizes the minimum energy efficiency among all the users with individual SINR constraints. We solve the optimization problem by transforming it into a semidefinite program with relaxation that can be efficiently solved. We compare our multiuser beamforming algorithm with the traditional beamforming scheme considered in previous works, which minimizes the total transmission power with individual SINR constraints. Simulation results show the advantage of using the proposed energy-efficient beamforming algorithm.