Relay Broadcast Channel with Confidential Messages

TL;DR

This paper explores how adding a relay node can enhance the secrecy capacity of broadcast channels with confidential messages, providing bounds and examples for various message configurations.

Contribution

It introduces new bounds on the capacity-equivocation region for relay broadcast channels with confidential messages, demonstrating improved secrecy capacity with relays.

Findings

Relay nodes increase secrecy capacity regions.

Inner and outer bounds are established for different message setups.

Gaussian examples illustrate capacity improvements.

Abstract

We investigate the effects of an additional relay node on the secrecy of broadcast channels by considering the model of relay broadcast channels with confidential messages. We show that this additional relay node can increase the achievable secrecy rate region of the broadcast channels with confidential messages. More specifically, first, we investigate the discrete memoryless relay broadcast channels with two confidential messages and one common message. Three inner bounds (with respect to decode-forward, generalized noise-forward and compress-forward strategies) and an outer bound on the capacity-equivocation region are provided. Second, we investigate the discrete memoryless relay broadcast channels with two confidential messages. Inner and outer bounds on the capacity-equivocation region are provided. Finally, we investigate the discrete memoryless relay broadcast channels with one confidential message and one common message. Inner and outer bounds on the capacity-equivocation region are provided, and the results are further explained via a Gaussian example. Compared with Csiszar-Korner's work on broadcast channels with confidential messages (BCC), we find that with the help of the relay node, the secrecy capacity region of the Gaussian BCC is enhanced.