Energy-efficient BS antenna configuration for downlink distributed MIMO system

In this paper, we study base station (BS) antenna configuration for downlink multi-cell multi-user distributed multiple input multiple output (MIMO) system to maximize its energy efficiency (EE). In order to obtain the optimal configuration of antennas and users, we first derive the EE expression by considering a realistic power consumption model (PCM). Then an energy-efficient optimization model with respect to the number N of radio access unit (RAU) antennas and the number K of users is formulated to obtain the optimal number Nopt of RAU antennas and the optimal number Kopt of users for maximizing the EE. The EE is concave with respect to the number of RAU antennas and users, so an iteration algorithm is proposed to obtain the optimization solution. The simulation results suggest that the proposed algorithm can obtain the optimal configuration of RAU antennas and supportable users and each user needs only about 2 BS antennas to maximize the EE with zero-forcing (ZF) precoding. Moreover, the proposed antenna configuration scheme can obviously improve the EE of distributed MIMO system.