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.
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.
In this paper, considering the worst case channel uncertainty, we propose a robust secure design with cooperative jamming strategy in decode-and-forward relay network. Practically, it is difficult for the full-duplex model to eliminate the self-interference and experience indicates that full-duplex schemes may not always outperform half-duplex schemes. Thus, we employ the hybrid full/half-duplex protocol to reduce the influence of self-interference. Considering imperfect eavesdropping channel condition, we propose a worst-case robust design to obtain jamming weights, which is solved through semi-definite program. Furthermore, we analyze secrecy rate and secrecy outage performance of the proposed scheme. As a benchmark, a traditional full-duplex multi-relay system based on equal-power is proposed for comparison. Simulation results demonstrate that our hybrid strategy with robust design outperforms the traditional full-duplex scheme.
This paper studies a robust resource allocation framework to enhance physical layer security where it is assumed that the system is equipped with a full-duplex (FD) receiver in contrast to conventional frameworks where a half-duplex (HD) receiver is at hand. Conventionally, relays are used as jammer to reduce the signal quality received by the eavesdroppers so as to increase the secrecy transmission rate between the legitimate transmitter and receiver. This is referred to as cooperative jamming (CJ). In a system equipped with a FD receiver, we propose to use the FD receiver as the jammer, i.e., the FD receiver simultaneously transmits jamming signals toward the eavesdropper while receiving data from the transmitter. The proposed scheme eliminates the need for external helpers, i.e., jamming relays which is welcome from practical point of view. We consider different scenarios to compare the proposed scheme against the CJ scheme in which, under a legitimate transmitter power constraint, optimal power allocation is obtained for each scenario to maximize the secrecy rate. To take into account the impact of imperfect state information of the channels between the eavesdropper and other nodes on the network, worst-case optimization approaches are considered. Simulation results demonstrate that for certain positions of the jamming relay and eavesdropper, the proposed system can outperform the conventional CJ schemes.
Secure transmission is possible in wireless communication due to physical layer security with the help of relay in the presence of eavesdroppers. In this system, we investigate the secrecy performance for desired users where undesired users, who are not selected for data reception, may overhear the message signal as eavesdroppers. Here, relay operate with decode-and-forward (DF) mode with full-duplex jamming (FDJ) under total transmit power constraint. First obtain the secrecy rate for half-duplex transmission (HDT), which requires two time slot for data reception and transmission. Second obtain the secrecy rate in FDJ. In this system, we use FDJ scheme to overcome the overhearing of eavesdroppers, in which a desired receiver send a jamming signal towards untrustworthy relay when relay receive a message signal from transmitter and then relay decode and forward the received signal towards desired receiver on the same time slot. Now receiver receives the message signal with jamming and only this desire receiver can subtract the jamming signal and also it will create an interference to prevent the overhearing of undesired receiver. The result indicate that secrecy rate of FDJ is better than the HDT.
This paper proposes a jointly cooperative relay and jamming protocol based on full-duplex (FD) capable relay to increase the source-destination secrecy rate in the presence of different types of eavesdroppers. In this so called FD-Relay with jamming (FDJ) protocol, the FD-Relay, first, simultaneously receives data and sends jamming to the eavesdropper, and, then, forwards the data, while the source jams the eavesdropper. Achievable secrecy rates of the proposed FDJ in the presence of different eavesdropper types and self-interference (SI) are derived and compared with those of the traditional half-duplex (HD) relay. The adaptive power allocation for secrecy rate maximization in a multi-carrier scenario for both proposed FDJ and HD-Relay is formulated as a non-convex optimization problem and corresponding iterative solution algorithm is developed using the difference-of-two-concave-functions (DC) programming technique. The simulation results confirm that FDJ offers significant improvements in the secrecy rate over the HD-Relay.
Considering existing eavesdroppers, this paper analyzes the secrecy outage probability (SOP) of the full-duplex (FD) relaying network with imperfect channel state information (CSI), where the decode-and-forward relay protocol is adopted. To enhance the physical-layer security, two relay selection schemes are proposed. The first scheme uses the maximum-minimum principle to select the optimal relay. The other selection scheme is based on partial signal-to-interference-plus-noise ratio. Then, the tight closed-form approximations of the SOP are obtained for three special CSI cases, respectively. Moreover, based on these approximated results, the effects of some system parameters are analyzed for the SOP of the relay system, including the CSI error, the number of relays, the signal-to-noise ratio (SNR) of the eavesdropper, and the residual self-interference caused by the FD model. The numerical results show that at low SNR of the eavesdropper, residual self-interference has a significantly impact on SOP, while at high SNR of the eavesdropper, this effect is negligible. In addition, the SOP of FD model is always superior to the half-duplex (HD) model when the number of relays changes.
This paper studies the secrecy outage probability of full-duplex (FD) relay networks in the presence of external eavesdropper and residual self-interference, where the FD relay can forward message or transmit jamming signal. Different with the existing researches which consider the full-duplex relay employs decode-and-forward (DF) protocol, we study the situation that the FD relay uses amplify-and-forward (AF) protocol, and propose a destination aided jamming scheme to further improve the secrecy performance when the FD relay transmits jamming. Furthermore, we compare the secrecy outage probability of four different schemes (i.e., AF forwarding scheme, AF destination- aided jamming scheme, DF forwarding scheme and DF jamming scheme), and give the answer that which mode the FD relay should employ with different system parameters.