A Hybrid Cooperative Coding Scheme for the Relay-Eavesdropper Channel

Peng Xu,Xuchu Dai,Zhiguo Ding

doi:10.3390/e16031819

Peng Xu, Xuchu Dai + Show 1 more

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https://doi.org/10.3390/e16031819

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Abstract

This paper considers the four-node relay-eavesdropper channel, where a relay node helps the source to send secret messages to the destination in the presence of a passive eavesdropper. For the discrete memoryless case, we propose a hybrid cooperative coding scheme, which is based on the combination of the partial decode-forward scheme, the noise-forward scheme and the random binning scheme. The key feature of the proposed hybrid cooperative scheme is that the relay integrates the explicit cooperation strategy and the implicit cooperation strategy by forwarding source messages and additional interference at the same time. The derived achievable secrecy rate shows that some existing works can be viewed as special cases of the proposed scheme. Then, the achievable secrecy rate is extended to the Gaussian channel based on Gaussian codebooks, and the optimal power policy is also identified in the high power region. Both the analysis and numerical results are provided to demonstrate that the proposed hybrid cooperative coding scheme outperforms the comparable ones, especially in the high power region.

Highlights

The concept of information theoretic secrecy was first introduced by Shannon in [1], where a key is used to protect confidential messages over noiseless transmissions
We have proposed a hybrid cooperative coding scheme, which enables the relay to integrate the explicit cooperation strategy and the implicit cooperation strategy by forwarding source messages and additional interference at the same time
The derived achievable secrecy rate shows that the proposed scheme outperforms some existing works

Summary

Introduction

The concept of information theoretic secrecy was first introduced by Shannon in [1], where a key is used to protect confidential messages over noiseless transmissions. When considering the noisy transmission, Wyner introduced the wiretap channel in [2], where the received signal at the eavesdropper was assumed to be a degraded version of the signal at the legitimate receiver. Csiszár and Körner extended this degraded wiretap channel to a more general broadcast channel with confidential messages and found the secrecy capacity in [3]. Multiple access channels (MACs) were studied in [6,7,8,9], where an external eavesdropper was introduced in [6,7], while each legitimate user in [8,9] acted as an eavesdropper for the messages intended to the other users. Relay channels were studied in [12,13,14,15,16,17], where an external eavesdropper was introduced in [12,13,14,15], while the relay node in [16,17] was an untrusted helper, i.e., this untrusted helper acted as an eavesdropper to the main receiver

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