In this paper, we consider secure transmission for the full duplex relay network. Aiming to improve the physical layer security, we propose a full duplex hybrid relaying-and-jamming (FDHRJ) scheme. In the FDHRJ scheme, we design a pre-coding matrix to form a jamming signal and let the relay simultaneously transmit both the desired signal and the jamming signal every slot. The destination can decode the desired signal and eliminate the jamming signal while the eavesdropper cannot do this. Based on the scheme, we derive an analytical expression of the system secrecy rate and the optimal power allocation between the desired signal and the jamming signal. The simulation results show that the proposed FDHRJ scheme with the optimal power allocation has better performance than the exiting schemes.
In this paper, we consider secure transmission for the full duplex relay network. Aiming to improve the physical layer security, we propose a full duplex hybrid relaying-and-jamming (FDHRJ) scheme. In the FDHRJ scheme, we design a pre-coding matrix to form a jamming signal and let the relay simultaneously transmit both the desired signal and the jamming signal every slot. The destination can decode the desired signal and eliminate the jamming signal while the eavesdropper cannot do this. Based on the scheme, we derive an analytical expression of the system secrecy rate and the optimal power allocation between the desired signal and the jamming signal. The simulation results show that the proposed FDHRJ scheme with the optimal power allocation has better performance than the exiting 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 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.
The relay networks face with such a circumstance that an eavesdropper overhears every hop of the relay networks. To solve the issue, we propose a full-duplex friendly-jamming relaying (FDFJR) scheme to secure the information transmissions for a two hop relay network, where a malicious eavesdropper attempts to overhear the private messages transferred by the transmitter and the relay. In the scheme, we take advantage of the capacity of simultaneous reception and transmission of fullduplex (FD) relay. Specifically, in the first hop, the full-duplex jamming relay (FDJR) receives the private information from the transmitter while transmitting the jamming signals to the malicious eavesdropper. And in the second hop, FDJR continues transferring the jamming signals to the eavesdropper, rather than merely amplifying and forwarding the information signals previously received. Furthermore, the ergodic secrecy capacity (ESC) of the networks is characterized and its asymptotical expression is derived. To maximize ESC, we formulate a novel power scheduling problem satisfying several key power and rate requirements. By solving the problem, an exact analytic solution regarding power allocation factor is acquired. Finally, numerical results are provided to validate the accuracy of analytical results and the superiority of our proposed scheme.
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.
We address the problem of secure wireless communications over an untrusted full-duplex (FD) relay based on the source jamming scheme. The optimal power allocation between the confidential signal and the jamming signal is derived to maximize the secrecy rate. Then, the corresponding secrecy outage probability (SOP) and the average secrecy rate (ASR) are analyzed. A tight approximation and an asymptotic result are further obtained for the single-antenna destination case both in simple forms. The large-antenna destination case is also analyzed rigorously. Further discussion reveals that transmit-power dependent self-interference has significant negative impact on the secrecy performance.
Simultaneous wireless information and power transfer (SWIPT) is a promising technique for energy-constrained wireless networks. To improve the security of SWIPT-enabled relay networks, in this paper, a full-duplex (FD) destination-aided jamming strategy is proposed, where a power splitting (PS) scheme is considered and two transmission phases are designed. In the first phase, the energy-limited half-duplex relay receives the signal superposed by confidential information and artificial noise (AN) from the source and destination, respectively. And then the FD destination transmits AN to the passive eavesdropper and receives the signal from the relay concurrently in the second phase. To maximize the secrecy capacity (SC), the individual optimizations of the PS ratio and power allocation (PA) coefficient are investigated, and the approximate optimal closed-form solutions of PS and PA ratios are derived. Besides, an iterative algorithm is also proposed to obtain the global optimal SC by updating the PS and PA ratios alternately. Simulation results confirm that the theoretical PS and PA ratios coincide closely with the exact results, and demonstrate that the optimal SC obtained by the iterative algorithm matches well with that given by the exhaustive search.