Secrecy Rate Maximization for Untrusted Relay Networks With Nonorthogonal Cooperative Transmission Protocols | IEEE Journals & Magazine | IEEE Xplore

Secrecy Rate Maximization for Untrusted Relay Networks With Nonorthogonal Cooperative Transmission Protocols


Abstract:

In this paper, a relay based network is considered where the source transmits confidential message to the destination via a nonregenerative relay. Due to the fact that th...Show More

Abstract:

In this paper, a relay based network is considered where the source transmits confidential message to the destination via a nonregenerative relay. Due to the fact that the relay is unidentified, and thus may wiretap the relayed message from source to destination. In this regard, two new half-duplex nonorthogonal amplify-and-forward (NAF) secure communication protocols are proposed, with different assumptions on the transmission ability of the destination, i.e., NAF-I for destination without transmission ability and NAF-II for destination with transmission ability. We separately derive the sufficient and necessary conditions to yield positive secrecy rate for these protocols under fixed source/destination transmission power, and discuss their joint power allocation that maximizes the system secrecy rate. Despite the nonconvexity of the considered power allocation problems, alternative optimization approach is proved useful in dealing with these problems, and the corresponding algorithms are proposed. We further prove the convergence of the proposed algorithms and analyze their complexity. The discussion is also extended to the orthogonal amplify-and-forward (OAF) based protocols, i.e., OAF-I or OAF-II, for comparison purpose. Our numerical results demonstrate the gain of the secrecy rate performance of the proposed NAF protocols over existing transmission protocols, and also verify the effectiveness of the designed alternative optimization algorithms.
Published in: IEEE Transactions on Vehicular Technology ( Volume: 67, Issue: 7, July 2018)
Page(s): 6325 - 6339
Date of Publication: 26 March 2018

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I. Introduction

Recently, leveraging relay to enhance wireless security has received considerable attentions [1], [2]. For these work, additional nodes are introduced into the network as relays who can provide extra degree of freedom in reinforcing the communication security. However, as mentioned in [3] and [4], all these work are based on an assumption that the relay has the same security clearance as the source and destination. In practical networks, there may exist relays with lower security clearance or untrustworthy relays that we need to take into consideration. Moreover, this issue becomes more serious if the untrusted relay is the only way for source and destination to establish connections between them.

References

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