On Beamformer Design for Multiuser MIMO Interference Channels

TL;DR

This paper analyzes linear beamformer design strategies for multiuser MIMO interference channels, focusing on interference alignment, max-SINR algorithms, and their optimality and convergence properties at high SNR.

Contribution

It establishes the relationship between two-layer interference alignment beamforming and max-SINR algorithms, proving their optimality and local exponential convergence at high SNR.

Findings

Interference alignment involves inner and outer precoders and decoders.

Max-SINR algorithm is optimal within linear beamforming at high SNR.

Max-SINR converges locally with exponential rate at high SNR.

Abstract

This paper considers several linear beamformer design paradigms for multiuser time-invariant multiple-input multiple-output interference channels. Notably, interference alignment and sum-rate based algorithms such as the maximum signal-to-interference-plus noise (max-SINR) algorithm are considered. Optimal linear beamforming under interference alignment consists of two layers; an inner precoder and decoder (or receive filter) accomplish interference alignment to eliminate inter-user interference, and an outer precoder and decoder diagonalize the effective single-user channel resulting from the interference alignment by the inner precoder and decoder. The relationship between this two-layer beamforming and the max-SINR algorithm is established at high signal-to-noise ratio. Also, the optimality of the max-SINR algorithm within the class of linear beamforming algorithms, and its local convergence with exponential rate, are established at high signal-to-noise ratio.