Secrecy in Cooperative Relay Broadcast Channels

TL;DR

This paper explores how user cooperation in relay broadcast channels enhances secrecy, proposing new coding schemes and deriving bounds, demonstrating positive secrecy rates in Gaussian channels with cooperation.

Contribution

It introduces a novel achievable scheme combining Marton's coding and compress-and-forward, and derives outer bounds for the secrecy rate region.

Findings

User cooperation increases the achievable secrecy region.

Both users can attain positive secrecy rates with cooperation in Gaussian channels.

The proposed scheme outperforms non-cooperative scenarios.

Abstract

We investigate the effects of user cooperation on the secrecy of broadcast channels by considering a cooperative relay broadcast channel. We show that user cooperation can increase the achievable secrecy region. We propose an achievable scheme that combines Marton's coding scheme for broadcast channels and Cover and El Gamal's compress-and-forward scheme for relay channels. We derive outer bounds for the rate-equivocation region using auxiliary random variables for single-letterization. Finally, we consider a Gaussian channel and show that both users can have positive secrecy rates, which is not possible for scalar Gaussian broadcast channels without cooperation.