# One- and Two-Way Relay Optimization for MIMO Interference Networks

## TL;DR

This paper develops optimization strategies for MIMO relay systems in multi-cell interference networks, aiming to minimize the maximum MSE at receivers using AF relaying with practical SDP solutions.

## Contribution

It introduces a simplified SDP-based approach for joint source, relay, and receiver matrix optimization in MIMO relay networks, reducing complexity compared to iterative methods.

## Key findings

- Proposed schemes effectively reduce maximum MSE in simulations.
- SDP-based solution offers a practical alternative to intractable optimal solutions.
- Numerical results demonstrate the efficiency of the proposed optimization methods.

## Abstract

This paper considers multiple-input multiple-output (MIMO) relay communication in multi-cellular (interference) systems in which MIMO source-destination pairs communicate simultaneously. It is assumed that due to severe attenuation and/or shadowing effects, communication links can be established only with the aid of a relay node. The aim is to minimize the maximal mean-square-error (MSE) among all the receiving nodes under constrained source and relay transmit powers. Both one- and two-way amplify-and-forward (AF) relaying mechanisms are considered. Since the exactly optimal solution for this practically appealing problem is intractable, we first propose optimizing the source, relay, and receiver matrices in an alternating fashion. Then we contrive a simplified semidefinite programming (SDP) solution based on the error covariance matrix decomposition technique, avoiding the high complexity of the iterative process. Numerical results reveal the effectiveness of the proposed schemes.