Communicating over a Classical-Quantum MAC with State Information Distributed at Senders

TL;DR

This paper studies the capacity limits of a classical-quantum multiple access channel with state information at the transmitters, proposing a new coding scheme that improves achievable rates over previous methods.

Contribution

It introduces a novel union coset coding scheme for classical-quantum MACs with state information, expanding the known inner bounds on capacity regions.

Findings

The new coding scheme outperforms IID random coding in certain cases.

Inner bounds derived are strictly larger for specific examples.

The approach generalizes classical Gelfand-Pinsker results to quantum settings.

Abstract

We consider the problem of communicating over a classical-quantum (CQ) multiple access channel with random classical states non-causally available at the transmitter, referred to as a QMSTx. QMSTx is a classical-quantum multiple access analogue of the channel considered by Gelfand and Pinsker in 1980. We undertake a Shannon-theoretic study and focus on the problem of characterizing inner bounds to the capacity region of a QMSTx. We propose a new coding scheme based on \textit{union coset codes} - codes possessing algebraic properties and derive a new inner bound that subsumes the inner based on IID random coding. We identify examples for which the derived inner bound is strictly larger.