Transmit Signal and Bandwidth Optimization in Multiple-Antenna Relay Channels

TL;DR

This paper investigates transmit signal and bandwidth optimization in multiple-antenna relay channels, evaluating capacity bounds and achievable rates for full-duplex and half-duplex relays with various strategies.

Contribution

It formulates the optimization problems as convex programs and compares decode-and-forward with compress-and-forward strategies based on relay placement.

Findings

Decode-and-forward is nearly optimal when relay is close to source.

Compress-and-forward performs well when relay is near destination.

Convex optimization effectively models capacity and rate maximization.

Abstract

Transmit signal and bandwidth optimization is considered in multiple-antenna relay channels. Assuming all terminals have channel state information, the cut-set capacity upper bound and decode-and-forward rate under full-duplex relaying are evaluated by formulating them as convex optimization problems. For half-duplex relays, bandwidth allocation and transmit signals are optimized jointly. Moreover, achievable rates based on the compress-and-forward transmission strategy are presented using rate-distortion and Wyner-Ziv compression schemes. It is observed that when the relay is close to the source, decode-and-forward is almost optimal, whereas compress-and-forward achieves good performance when the relay is close to the destination.