Joint Source and Relay Design for Multi-user MIMO Non-regenerative Relay Networks with Direct Links

TL;DR

This paper proposes a joint design of source precoding and relay processing matrices for multi-user MIMO relay networks with direct links, optimizing capacity and MSE criteria through an iterative algorithm.

Contribution

It introduces a novel joint optimization framework with structured matrices and an iterative algorithm for MU-MIMO relay networks considering capacity and MSE.

Findings

The proposed algorithm outperforms existing methods in simulations.

Structured matrices simplify the joint optimization process.

Capacity and MSE optimal matrices share similar structures.

Abstract

In this paper, we investigate joint source precoding matrices and relay processing matrix design for multi-user multiple-input multiple-output~(MU-MIMO) non-regenerative relay networks in the presence of the direct source-destination~(S-D) links. We consider both capacity and mean-squared error~(MSE) criterions subject to the distributed power constraints, which are nonconvex and apparently have no simple solutions. Therefore, we propose an optimal source precoding matrix structure based on the point-to-point MIMO channel technique, and a new relay processing matrix structure under the modified power constraint at relay node, based on which, a nested iterative algorithm of jointly optimizing sources precoding and relay processing is established. We show that the capacity based optimal source precoding matrices share the same structure with the MSE based ones. So does the optimal relay processing matrix. Simulation results demonstrate that the proposed algorithm outperforms the existing results.