Diversity-Multiplexing Tradeoff for the Interference Channel with a Relay

TL;DR

This paper investigates the diversity-multiplexing tradeoff in a slow fading interference channel with a relay, deriving bounds for various relaying schemes and identifying conditions for optimality and benefits of relaying.

Contribution

It provides new inner bounds on the DMT region for the interference channel with a relay, including conditions for optimality and scenarios where relaying improves performance.

Findings

CF and DF schemes achieve optimal DMT under certain conditions.

In some cases, the interference channel's DMT matches that of parallel relay channels.

Adding a relay can strictly enlarge the DMT region under specific conditions.

Abstract

We study the diversity-multiplexing tradeoff (DMT) for the slow fading interference channel with a relay (ICR). We derive four inner bounds on the DMT region: the first is based on the compress-and-forward (CF) relaying scheme, the second is based on the decode-and-forward (DF) relaying scheme, and the last two bounds are based on the half-duplex (HD) and full-duplex (FD) amplify-and-forward (AF) schemes. For the CF and DF schemes, we find conditions on the channel parameters and the multiplexing gains, under which the corresponding inner bound achieves the optimal DMT region. We also identify cases in which the DMT region of the ICR corresponds to that of two parallel slow fading relay channels, implying that interference does not decrease the DMT for each pair, and that a single relay can be DMT-optimal for two pairs simultaneously. For the HD-AF scheme we derive conditions on the channel coefficients under which the proposed scheme achieves the optimal DMT for the AF-based relay channel. Lastly, we identify conditions under which adding a relay strictly enlarges the DMT region relative to the interference channel without a relay.