Cooperative Multiplexing in the Multiple Antenna Half Duplex Relay Channel

TL;DR

This paper demonstrates that half-duplex relay cooperation can enhance multiplexing gains in wireless networks, with performance depending on terminal distances, and introduces a simple scheme achieving MIMO DMT for certain gains.

Contribution

It shows cooperative multiplexing gain is achievable with a half-duplex relay and characterizes the DMT performance based on terminal distances.

Findings

Multiplexing gain can surpass direct link performance.

Relay scheme listening 1/3 and transmitting 2/3 achieves 2x2 MIMO DMT.

Performance depends on relative distances between terminals.

Abstract

Cooperation between terminals has been proposed to improve the reliability and throughput of wireless communication. While recent work has shown that relay cooperation provides increased diversity, increased multiplexing gain over that offered by direct link has largely been unexplored. In this work we show that cooperative multiplexing gain can be achieved by using a half duplex relay. We capture relative distances between terminals in the high SNR diversity multiplexing tradeoff (DMT) framework. The DMT performance is then characterized for a network having a single antenna half-duplex relay between a single-antenna source and two-antenna destination. Our results show that the achievable multiplexing gain using cooperation can be greater than that of the direct link and is a function of the relative distance between source and relay compared to the destination. Moreover, for multiplexing gains less than 1, a simple scheme of the relay listening 1/3 of the time and transmitting 2/3 of the time can achieve the 2 by 2 MIMO DMT.