Max-Min Power Control in Downlink Massive MIMO with Distributed Antenna Arrays

TL;DR

This paper develops a max-min power control algorithm for distributed antenna array massive MIMO systems, improving user throughput and accounting for correlated fading effects, with significant performance gains demonstrated.

Contribution

It introduces a closed-form SINR expression and a network-wide power control method tailored for DAA massive MIMO with arbitrary antenna deployment.

Findings

Up to 55% increase in average per-user throughput.

Channel covariance significantly impacts DAA massive MIMO performance.

Proposed algorithm ensures uniform quality of service across users.

Abstract

In this paper, we investigate optimal downlink power allocation in massive multiple-input multiple-output (MIMO) networks with distributed antenna arrays (DAAs) under correlated and uncorrelated channel fading. In DAA massive MIMO, the base station (BS) consists of multiple antenna sub-arrays. Notably, the antenna sub-arrays are deployed in arbitrary locations within a DAA massive MIMO cell. Consequently, the distance-dependent large-scale propagation coefficients are different from a user to these different antenna sub-arrays, which makes power control a challenging problem. We assume that the network operates in time-division duplex mode, where each BS obtains the channel estimates via uplink pilots. Based on the channel estimates, the BSs perform maximum-ratio transmission in the downlink. We then derive a closed-form signal-to-interference-plus-noise ratio (SINR) expression, where the channels are subject to correlated fading. Based on the SINR expression, we propose a networkwide max-min power control algorithm to ensure that each user in the network receives a uniform quality of service. Numerical results demonstrate the performance advantages offered by DAA massive MIMO. For some specific scenarios, DAA massive MIMO can improve the average per-user throughput up to 55%. Furthermore, we demonstrate that channel fading covariance is an important factor in determining the performance of DAA massive MIMO.