Two-User Interference Channels with Local Views: On Capacity Regions of TDM-Dominating Policies

TL;DR

This paper investigates the capacity regions of two-user interference channels with limited local channel state information, showing TDM suffices in most cases and identifying conditions where more advanced schemes could outperform TDM.

Contribution

It characterizes the capacity regions under local views in interference channels and identifies when TDM is optimal or when more complex strategies are needed.

Findings

TDM is sufficient for five out of seven local views in the deterministic model.

In two local views, knowledge of outgoing interference links can enable outperforming TDM.

Results extend to bounded gap characterizations of Gaussian interference channels.

Abstract

We study the capacity regions of two-user interference channels where transmitters base their transmission schemes on local views of the channel state. Under the local view model, each transmitter knows only a subset of the four channel gains, which may be mismatched from the other transmitter. We consider a set of seven local views, and find that for five out of the seven local views, TDM is sufficient to achieve the qualified notion of capacity region for the linear deterministic interference channel which approximates the Gaussian interference channel. For these five local views, the qualified capacity result implies that no policy can achieve a rate point outside the TDM region without inducing a corner case of sub-TDM performance in another channel state. The common trait shared by the two remaining local views - those with the potential to outperform TDM - is transmitter knowledge of the outgoing interference link accompanied by some common knowledge of state, emphasizing their importance in creating opportunities to coordinate usage of more advanced schemes. Our conclusions are extended to bounded gap characterizations of the capacity region for the Gaussian interference channel.