Multiaccess Channel with Partially Cooperating Encoders and Security Constraints

TL;DR

This paper investigates the capacity and secrecy limits of a two-user multi-access channel with partial encoder cooperation and an eavesdropper, providing bounds and conditions for optimal secure communication.

Contribution

It introduces new bounds on the capacity-equivocation region for a partially cooperative multi-access channel with security constraints, extending Willems's model.

Findings

Inner and outer bounds on capacity-equivocation region for DM case

Bounds on secrecy capacity for Gaussian model

Conditions where bounds coincide in extreme cooperation cases

Abstract

We study a special case of Willems's two-user multi-access channel with partially cooperating encoders from a security perspective. This model differs from Willems's setup in that only one encoder, Encoder 1, is allowed to conference; Encoder 2 does not transmit any message, and there is an additional passive eavesdropper from whom the communication should be kept secret. For the discrete memoryless (DM) case, we establish inner and outer bounds on the capacity-equivocation region. The inner bound is based on a combination of Willems's coding scheme, noise injection and additional binning that provides randomization for security. For the memoryless Gaussian model, we establish lower and upper bounds on the secrecy capacity. We also show that, under certain conditions, these bounds agree in some extreme cases of cooperation between the encoders. We illustrate our results through some numerical examples.