Interference Alignment at Finite SNR for Time-Invariant Channels

TL;DR

This paper develops a lattice interference alignment technique to derive achievable rate regions at finite SNR for certain time-invariant Gaussian interference channels with rational gains, extending beyond asymptotic degrees of freedom results.

Contribution

It introduces a new coding theorem for the two-user Gaussian multiple-access channel using a single linear code, applicable to interference channels with rational gains.

Findings

Explicit finite SNR rate region derived

Extends known degrees of freedom results

Provides insights into interference management at practical SNR levels

Abstract

An achievable rate region, based on lattice interference alignment, is derived for a class of time-invariant Gaussian interference channels with more than two users. The result is established via a new coding theorem for the two-user Gaussian multiple-access channel where both users use a single linear code. The class of interference channels treated is such that all interference channel gains are rational. For this class of interference channels, beyond recovering the known results on the degrees of freedom, an explicit rate region is derived for finite signal-to-noise ratios, shedding light on the nature of previously established asymptotic results.