Energy Efficiency Optimization for MIMO Distributed Antenna Systems

In this paper, we propose a transmit covariance optimization method to maximize the energy efficiency (EE) for the single-user distributed antenna system, where both the distributed antenna (DA) ports and the user are equipped with multiple antennas. Unlike previous related works, both the rate requirement and DA port selection are taken into consideration. Given this setup, we first propose an optimal transmit covariance optimization method to solve the EE optimization problem under fixed set of active DA ports and then the active DA port selection algorithm. For the transmit covariance optimization method, we split this problem into three subproblems, i.e., rate maximization problem, EE maximization problem without rate constraints, and power minimization problem. Then, a novel distance-based DA port selection method is proposed to determine the optimal set of active DA ports. Simulation results show that the performance of the proposed DA port selection is almost identical to the optimal exhaustive search method with significantly reduced computational complexity, and significantly outperforms the existing EE optimization methods.