The Wideband Slope of Interference Channels: The Small Bandwidth Case

TL;DR

This paper analyzes the low-SNR performance of finite bandwidth interference channels, revealing that the wideband slope per user is generally less than 2/K, contrasting with the large bandwidth case, and proposes an interference alignment scheme for gains.

Contribution

It characterizes the wideband slope in the small bandwidth regime and introduces an interference alignment scheme to improve performance.

Findings

Wideband slope per user is less than 2/K in the small bandwidth regime.

Contrasts with large bandwidth case where a slope of 1 per user is achievable.

Proposes an interference alignment scheme that provides some performance gains.

Abstract

This paper studies the low-SNR regime performance of a scalar complex K -user interference channel with Gaussian noise. The finite bandwidth case is considered, where the low-SNR regime is approached by letting the input power go to zero while bandwidth is small and fixed. We show that for all \delta>0 there exists a set with non-zero measure (probability) in which the wideband slope per user satisfies Slope<2/K+\delta . This is quite contrary to the large bandwidth case [ShenAHM11IT], where a slope of 1 per user is achievable with probability 1. We also develop an interference alignment scheme for the finite bandwidth case that shows some gain.