Energy efficient power allocation with joint antenna and user selection in massive MIMO systems

The problem of maximizing energy efficiency (EE) is considered in this paper. The system in question is a massive multiple-input multiple-output (MIMO) system that transmits information simultaneously in the uplink and downlink. To maximize EE, an optimal antenna selection strategy is used to send information. Furthermore, we propose an optimal user selection method and then obtain their optimal allocated power. The optimization problem of the system has two constraints, including power limitations in the uplink and downlink. Due to the non-convexity and being constrained of the optimization problem, in order to obtain the optimal power of users, it must first be converted to a convex problem form and then turned into an unconstrained problem using the Lagrange dual function method. The bisection algorithm is utilized to select the optimal set of active antennas for sending information. The cross-entropy algorithm with the proposed algorithm is used simultaneously to select the set of users and determine their optimal power values. The results of computer simulations show that the proposed selection schemes of antennas and users significantly improve the system performance.