Joint Antenna Selection and Power Allocation for an Energy-efficient Massive MIMO System

A joint antenna selection and power allocation scheme is proposed for a downlink massive multiple-input multiple-output system under perfect channel state information. Based on a tractable lower bound of the achievable downlink rate with linear zero-forcing preceding, a nonconvex energy efficiency optimization problem is formulated with nonlinear constraints. Since the optimization variables are highly interrelated, it is impractical to directly derive the closed-form solution to the original problem. To solve this problem, an effective iterative algorithm that maximizes energy efficiency is proposed according to the Lagrangian dual method, where the optimal number of transmit antennas and power allocation are solved iteratively until convergence. Numerical results demonstrate the effectiveness of the proposed algorithm.