Interference Channels with Half-Duplex Source Cooperation

TL;DR

This paper characterizes the sum capacity of Gaussian interference channels with in-band, half-duplex, bidirectional source cooperation under symmetric channel gains, introducing new bounds and analyzing unidirectional cooperation as a cognitive radio scenario.

Contribution

It provides the first characterization of sum capacity for half-duplex, in-band, bidirectional source cooperation in symmetric Gaussian interference channels, with novel bounds and analysis of unidirectional cooperation.

Findings

Sum capacity characterized for bidirectional cooperation

Constant-gap approximation for unidirectional cooperation

New inner and outer bounds derived

Abstract

The performance gain by allowing half-duplex source cooperation is studied for Gaussian interference channels. The source cooperation is {\em in-band}, meaning that each source can listen to the other source's transmission, but there is no independent (or orthogonal) channel between the sources. The half-duplex constraint supposes that at each time instant the sources can either transmit or listen, but not do both. Our main result is a characterization of the sum capacity when the cooperation is bidirectional and the channel gains are symmetric. With unidirectional cooperation, we essentially have a cognitive radio channel. By requiring the primary to achieve a rate close to its link capacity, the best possible rate for the secondary is characterized within a constant. Novel inner and outer bounds are derived as part of these characterizations.