The diversity-multiplexing tradeoff of the symmetric MIMO 2-user interference channel

TL;DR

This paper characterizes the fundamental diversity-multiplexing tradeoff of the symmetric 2-user MIMO interference channel with channel state information, showing how coding schemes and interference levels affect achievable performance.

Contribution

It provides the first complete DMT characterization for the symmetric 2-user MIMO IC with CSIT and establishes thresholds where CSIT benefits diminish.

Findings

Achievability of DMT via Han-Kobayashi coding scheme.

Threshold interference level where CSIT and No-CSIT DMT coincide.

DMT characterization for non-symmetric ICs with different antenna configurations.

Abstract

The fundamental diversity-multiplexing tradeoff (DMT) of the quasi-static fading, symmetric $2$-user MIMO interference channel (IC) with channel state information at the transmitters (CSIT) and a short term average power constraint is obtained. The general case is considered where the interference-to-noise ratio (INR) at each receiver scales differently from the signal-to-noise ratio (SNR) at the receivers. The achievability of the DMT is proved by showing that a simple Han-Kobayashi coding scheme can achieve a rate region which is within a constant (independent of SNR) number of bits from a set of upper bounds to the capacity region of the IC. In general, only part of the DMT curve with CSIT can be achieved by coding schemes which do not use any CSIT (No-CSIT). A result in this paper establishes a threshold for the INR beyond which the DMT with CSIT coincides with that with No-CSIT. Our result also settles one of the conjectures made in~\cite{EaOlCv}. Furthermore, the fundamental DMT of a class of non-symmetric ICs with No-CSIT is also obtained wherein the two receivers have different numbers of antennas.