Two-way Interference Channels

TL;DR

This paper analyzes two-way interference channels, demonstrating how feedback via the backward channel can enhance capacity, with inner and outer bounds matching in a linear deterministic model, and interaction providing significant gains.

Contribution

It introduces a new analysis of two-way interference channels, showing how feedback and interaction can significantly improve capacity, with matching bounds in a linear deterministic setting.

Findings

Backward IC can be more efficient for feedback than independent messages.

Feedback can increase capacity even when considering feedback costs.

Interaction can yield arbitrarily large capacity gains.

Abstract

We consider two-way interference channels (ICs) where forward and backward channels are ICs but not necessarily the same. We first consider a scenario where there are only two forward messages and feedback is offered through the backward IC for aiding forward-message transmission. For a linear deterministic model of this channel, we develop inner and outer bounds that match for a wide range of channel parameters. We find that the backward IC can be more efficiently used for feedback rather than if it were used for sending its own independent backward messages. As a consequence, we show that feedback can provide a net increase in capacity even if feedback cost is taken into consideration. Moreover we extend this to a more general scenario with two additional independent backward messages, from which we find that interaction can provide an arbitrarily large gain in capacity.