Low-complexity downlink MMSE beamforming in massive MIMO systems

Abstract

Massive MIMO (multiple-input-multiple-output) has been identified as a key technology to improve the cellular system throughput by several orders of magnitude. One practical concern of the implementation of massive MIMO lies in the high computational complexity for coherent and joint signal processing over a large number of antennas. To address this issue, we propose a low-complexity fixed-point algorithm to solve the downlink MMSE beamforming problem in massive MIMO systems. Specifically, the proposed algorithm has a linear complexity in the transmit antenna number, rendering it scalable in large systems. Through both analysis and numerical simulations, we show that the proposed algorithm has much lower complexity than the widely adopted existing algorithms, such as the interior point method and gradient descent method.