Abstract
Full duplex (FD) protocol has been widely used in wireless communications, which could transmit and receive signals at the meantime. In this paper, considering the worst-case channel uncertainty, opportunistic relaying and jamming strategy in decode-and-forward (DF) hybrid full/half-duplex (HD) relay system is proposed to enhance security. Specifically, the relay works in FD protocol to receive the confidential signals and transmit jamming signals at the first time slot. Then, the relay switches to HD protocol to transmit the decoded signals. Meanwhile, jammers emit cooperative jamming (CJ) signals to interfere the eavesdropper at two transmission slots. Suppose that imperfect eavesdropper channel condition is considered, we propose a worst-case robust design to obtain distributed jamming weights, which is solved through semi-definite program (SDP). Furthermore, we analyze secrecy rate and secrecy outage performance of the proposed scheme. As a benchmark, a traditional relay selection strategy with HD protocol in distributed relay system is listed for comparison. Simulation results demonstrate that our hybrid scheme with robust design outperforms the traditional relay selection scheme, because the traditional scheme does not consider hybrid FD/HD protocols and robust design based on imperfect channel conditions.
Highlights
Due to the broadcast nature of wireless channels which makes communication ubiquitously accessible, security becomes one of the most important issues in wireless communications
We propose a hybrid Full duplex (FD)/HD strategy and opportunistic proactive relay selection approach in our model, where the best relay is selected to switch between FD and HD operation to DF confidential signals
We propose a worst-case robust design to obtain the cooperative jamming (CJ) beamformer under channel uncertainty to improve secrecy performance, while traditional relay selection scheme [19] is based on estimated eavesdropping channel state information (ECSI)
Summary
Due to the broadcast nature of wireless channels which makes communication ubiquitously accessible, security becomes one of the most important issues in wireless communications. To enhance secrecy performance of a multiple-input-single-outputsingle-eavesdropper (MISOSE) relay system, a joint information beamforming and jamming beamforming strategy were proposed to guarantee both transmitting security and receiving security for a FD base station in [9]. We investigate the secrecy performance of opportunistic relaying and jamming in hybrid FD/HD relay network with channel uncertainty. Since the wireless system tries to enhance secrecy performance through signal processing at distributed jammers, the system requires the receiving nodes feedback corresponding CSI to jammers. The goal of E is to intercept private message and to feedback false training signals to interfere the estimation on S-E and Ji-E links Since we assume the ECSI at jamming nodes are imperfect, we consider DUM, where the error is deterministically bounded, i.e., eje ∈ R{e : ‖e‖ ≤ ε}, where ε is assumed to be the upper bound on the channel uncertainty
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