Selective-Fading Multiple-Access MIMO Channels: Diversity-Multiplexing Tradeoff and Dominant Outage Event Regions

TL;DR

This paper determines the optimal diversity-multiplexing tradeoff for selective-fading MIMO multiple-access channels, linking error events to outage regions and providing code design insights for improved reliability.

Contribution

It establishes the optimal DM tradeoff for these channels and introduces a novel relation between error events and outage regions, guiding code design.

Findings

Maximum diversity order is dictated by a single dominant outage event.

The relation between error mechanisms and outage regions is characterized.

Code design criteria are derived for distributed space-time codes.

Abstract

We establish the optimal diversity-multiplexing (DM) tradeoff for coherent selective-fading multiple-access MIMO channels and provide corresponding code design criteria. As a byproduct, on the conceptual level, we find an interesting relation between the DM tradeoff framework and the notion of dominant error event regions, first introduced in the AWGN case by Gallager, IEEE Trans. IT, 1985. This relation allows us to accurately characterize the error mechanisms in MIMO fading multiple-access channels. In particular, we find that, for a given rate tuple, the maximum achievable diversity order is determined by a single outage event that dominates the total error probability exponentially in SNR. Finally, we examine the distributed space-time code construction proposed by Badr and Belfiore, Int. Zurich Seminar on Commun., 2008, using the code design criteria derived in this paper.