Joint beamforming and power control in downlink multiuser multiple-input multiple-output systems

Abstract

In this paper, we study joint beamforming and power control for downlink multiple-input multiple-output systems with multiple users and target values for signal-to-interference plus noise ratios SINRs. We formulate this as a constrained optimization problem of minimizing total interference subject to constraints on the beamforming vector norms, target SINRs, and total transmit power. Necessary and sufficient conditions satisfied by the optimal beamformer and power allocation are presented, and a new algorithm for joint beamforming and power control is proposed. This adapts the beamforming vectors and transmit powers incrementally, and it stops when the specified SINR targets are achieved with minimum powers. The proposed algorithm is illustrated with numerical results obtained from simulations, which study its convergence and compare it with other similar algorithms. Copyright © 2013 John Wiley & Sons, Ltd.