Opportunistic Wireless Relay Networks: Diversity-Multiplexing Tradeoff

TL;DR

This paper extends opportunistic analysis to complex relay network topologies, proposing new methods and analyzing their diversity-multiplexing tradeoff in high-SNR regimes, demonstrating near-optimal and optimal relay protocols.

Contribution

It develops techniques for broader opportunistic analysis, proposes new relay strategies, and characterizes their DMT performance in various network geometries.

Findings

Simple selection strategies are DMT-optimal in multi-user single-relay networks.

Compress-forward relaying achieves the DMT upper bound in certain relay channels.

Finite-precision feedback performs nearly as well as full channel state information.

Abstract

Opportunistic analysis has traditionally relied on independence assumptions that break down in many interesting and useful network topologies. This paper develops techniques that expand opportunistic analysis to a broader class of networks, proposes new opportunistic methods for several network geometries, and analyzes them in the high-SNR regime. For each of the geometries studied in the paper, we analyze the opportunistic DMT of several relay protocols, including amplify-and-forward, decode-and-forward, compress-and-forward, non-orthogonal amplify-forward, and dynamic decode-forward. Among the highlights of the results: in a variety of multi-user single-relay networks, simple selection strategies are developed and shown to be DMT-optimal. It is shown that compress-forward relaying achieves the DMT upper bound in the opportunistic multiple-access relay channel as well as in the opportunistic nxn user network with relay. Other protocols, e.g. dynamic decode-forward, are shown to be near optimal in several cases. Finite-precision feedback is analyzed for the opportunistic multiple-access relay channel, the opportunistic broadcast relay channel, and the opportunistic gateway channel, and is shown to be almost as good as full channel state information.