MAC Wiretap Channels with Confidential and Open Messages: Improved Achievable Region and Low-complexity Precoder Design

TL;DR

This paper expands the achievable region for MAC wiretap channels with both secret and open messages and proposes a low-complexity precoder design, improving security and efficiency in multi-user communication systems.

Contribution

It introduces a generally enlarged achievable region for multi-user MAC wiretap channels and offers a new, scalable achievability proof method.

Findings

Enlarged achievable region for MAC-WT channels with open and secret messages.

General achievability proof applicable to any number of users.

Improved precoder design with low complexity.

Abstract

This paper investigates the achievable region and precoder design for multiple access wiretap (MAC-WT) channels, where each user transmits both secret and open (i.e., non-confidential) messages. All these messages are intended for the legitimate receiver (or Bob for brevity) and the eavesdropper (Eve) is interested only in the secret messages of all users. By allowing users with zero secret message rate to act as conventional MAC channel users with no wiretapping, we show that the achievable region of the discrete memoryless (DM) MAC-WT channel given in [1] can be enlarged. In [1], the achievability was proven by considering the two-user case, making it possible to prove a key auxiliary lemma by directly using the Fourier-Motzkin elimination procedure. However, this approach does not generalize to the case with any number of users. In this paper, we provide a new region that generally enlarges that in [1] and provide general achievability proof.