Two-User Erasure Interference Channels with Local Delayed CSIT

TL;DR

This paper investigates the capacity of two-user erasure interference channels with local delayed channel state information, proposing a strategy that achieves the outer-bound and analyzing when delayed knowledge impacts capacity.

Contribution

It introduces a transmission strategy relying on local delayed knowledge that matches the outer-bound and explores the impact of channel state information on capacity.

Findings

The proposed strategy achieves the outer-bound for certain delayed CSIT scenarios.

Local delayed knowledge can sometimes be as ineffective as having no channel state information.

Spatial correlation can nullify the benefits of delayed channel knowledge.

Abstract

We study the capacity region of two-user erasure interference channels with local delayed channel state information at the transmitters. In our model, transmitters have local mismatched outdated knowledge of the channel gains. We propose a transmission strategy that only relies on the delayed knowledge of the {\it outgoing} links at each transmitter and achieves the outer-bound for the scenario in which transmitters learn the entire channel state with delay. Our result reveals the subset of the channel state information that affects the capacity region the most. We also identify cases in which local delayed knowledge of the channel state does not provide any gain over the zero knowledge assumption. To do so, we revisit a long-known intuition about interference channels that as long as the marginal distributions at the receivers are conserved, the capacity remains the same. We take this intuition and impose a certain spatial correlation among channel gains such that the marginal distributions remain unchanged. Then we provide an outer-bound on the capacity region of the channel with correlation that matches the capacity region when transmitters do not have access to channel state information.