On Two-way Communications for Cooperative Multiple Source Pairs Through a Multi-antenna Relay

TL;DR

This paper investigates optimal and suboptimal beamforming strategies for multi-antenna relays facilitating two-way communication among multiple single-antenna source pairs, aiming to maximize SINR and manage interference.

Contribution

It derives the optimal beamforming matrix for maximum SINR and introduces two new non-zero-forcing beamforming schemes considering interference tradeoffs.

Findings

Optimal beamforming matrix structure achieved maximum SINR.

Proposed non-zero-forcing schemes effectively balance signal preservation and interference suppression.

Joint grouping and beamforming improve SINR in large source pair scenarios with low relay SNR.

Abstract

We study amplified-and-forward (AF)-based two-way relaying (TWR) with multiple source pairs, which are exchanging information through the relay. Each source has single antenna and the relay has multi-antenna. The optimal beamforming matrix structure that achieves maximum signal-to-interference-plus-noise ratio (SINR) for TWR with multiple source pairs is derived. We then present two new non-zero-forcing based beamforming schemes for TWR, which take into consideration the tradeoff between preserving the desired signals and suppressing inter-pair interference between different source pairs. Joint grouping and beamforming scheme is proposed to achieve a better signal-to-interference-plus-noise ratio (SINR) when the total number of source pairs is large and the signal-to-noise ratio (SNR) at the relay is low.