Physical Layer Security in Cooperative AF Relay Networks Over Mixed Nakagami-m and Double Nakagami-m Fading Channels: Performance Evaluation and Optimization

What is it about?

We investigate the secrecy performance of a cooperative relaying network, wherein a fixed source communicates with a fixed destination via an amplify-and-forward mobile relay in the presence of a passive mobile eavesdropper. We assume that the source-to-relay channel and relay-to-destination channel experience Nakagami-m fading, whereas relay-to-eavesdropper link follows double Nakagami-m fading. Under such a mixed fading environment, we derive the novel tight closed-form expressions for the secrecy outage probability (SOP), probability of non-zero secrecy capacity, and intercept probability of the considered system. We also deduce the asymptotic secrecy outage and intercept probability expressions in the high signal-to-noise ratio regime to highlight the impact of fading parameters and channel conditions on the secrecy diversity order. It is shown that the system can achieve secrecy diversity order of min(mSR,mRD) in terms of SOP, and mRD in terms of intercept probability, where mSR and mRD represent the fading severity parameters between source and relay and between relay and destination, respectively. We also formulate and investigate analytically two optimization problems, namely, optimal relay location with fixed power allocation, and optimal power allocation with fixed relay location, to minimize the system SOP. We verify analytical findings via numerical and simulation results.

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Why is it important?

V2X communications are gaining importance owing to the vast number of ITS applications they support. However, such networks depend on wireless communications over an open and vulnerable wireless medium such networks are susceptible to various attacks and misuse activities. Traditional key-based cryptographic techniques may not be sufficient due to the dynamic and decentralized nature of these networks. This motivated us to exploit the physical layer security to secure such communication networks at the physical layer to strengthen the existing security infrastructure.

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