A Note on Multiple-Access Channels with Strictly-Causal State Information

TL;DR

This paper introduces a new inner bound for the capacity region of a memoryless multiple-access channel with strictly causal state information at the encoders, demonstrating it can be strictly better than previous bounds through specific examples.

Contribution

It presents a novel inner bound that improves upon existing bounds for channels with strictly causal state information, including a case with two independent states.

Findings

New inner bound contains previous bounds

Example shows the bound can be strictly better

Application to two-state scenario confirms improved bounds

Abstract

We propose a new inner bound on the capacity region of a memoryless multiple-access channel that is governed by a memoryless state that is known strictly causally to the encoders. The new inner bound contains the previous bounds, and we provide an example demonstrating that the inclusion can be strict. A variation on this example is then applied to the case where the channel is governed by two independent state sequences, where each transmitter knows one of the states strictly causally. The example proves that, as conjectured by Li et al., an inner bound that they derived for this scenario can indeed by strictly better than previous bounds.