In this paper we propose an energy harvesting-based cooperative jamming and full-duplex relaying scheme to enhance the secrecy rate for wireless communication between a source node and a destination node, in the presence of an eavesdropper. To characterize the performance, we develop a mathematical analysis framework for instantaneous and average secrecy rates. We consider the practical interference limited scenario, and derive exact closed-form expressions for the cumulative distribution function of the signal-to-noise-plus-interference ratio (SNIR) at the destination and eavesdropper nodes. Accordingly, the asymptotic average secrecy rates are derived. We show that the proposed protocol improves the average secrecy rate of a wireless cooperative network substantially. However, the instantaneous secrecy rate performance gain is highly depend on the duration of energy harvesting, the amount of self-interference and the corresponding channels and positions of the nodes in the system.
In this paper we propose an energy harvesting-based cooperative jamming and full-duplex relaying scheme to enhance the secrecy rate for wireless communication between a source node and a destination node, in the presence of an eavesdropper. To characterize the performance, we develop a mathematical analysis framework for instantaneous and average secrecy rates. We consider the practical interference limited scenario, and derive exact closed-form expressions for the cumulative distribution function of the signal-to-noise-plus-interference ratio (SNIR) at the destination and eavesdropper nodes. Accordingly, the asymptotic average secrecy rates are derived. We show that the proposed protocol improves the average secrecy rate of a wireless cooperative network substantially. However, the instantaneous secrecy rate performance gain is highly depend on the duration of energy harvesting, the amount of self-interference and the corresponding channels and positions of the nodes in the system.
Wireless energy harvesting, physical-layer security, and full-duplex wireless are important, emerging fifth generation (5G) technologies. In this paper, we thus investigate a source-destination link with an energy-harvesting full-duplex relay and a jammer (to degrade the eavesdropper channel) in the presence of an eavesdropper. Thus, to exploit energy harvesting and to improve security, we propose a full-duplex jammer (FDJ) protocol and its half-duplex version (HDJ). Two cases for availability of the eavesdropper channel state information (ECSI) are considered: complete ECSI and incomplete ECSI. For both FDJ and HDJ protocols and for complete ECSI, we derive the instantaneous and average secrecy rates and compute optimal time split for energy harvesting. To gain more insights, we consider a practical interference-limited scenario and derive closed-form cumulative distribution function of the signal-to-interference plus noise ratio at the destination and eavesdropper nodes. Comparatively, we show that FDJ improves instantaneous secrecy rate over HDJ. However, the degree of improvement is highly dependent on time split for energy harvesting, amount of self-interference, the channel gains, and locations of the nodes. Our findings reveal that FDJ increases the average secrecy rate 150% over HDJ and 260% over HD relaying without jammer. For incomplete ECSI scenario, we derive asymptotic secrecy outage and show that FDJ performs better for small-to-medium values of source powers; otherwise, HDJ yields a higher gain.
This paper develops a new cooperative jamming protocol, termed accumulate-and-jam (AnJ), to improve physical layer security in wireless communications. Specifically, a full-duplex (FD) friendly jammer is deployed to secure the direct communication between source and destination in the presence of a passive eavesdropper. We consider the friendly jammer as an energy-constrained node without embedded power supply but with an energy harvesting unit and rechargeable energy storage; it can thus harvest energy from the radio frequency signals transmitted by the source, accumulate the energy in its battery, and then use this energy to perform cooperative jamming. In the proposed AnJ protocol, based on the energy status of the jammer and the channel state of source-destination link, the system operates in either dedicated energy harvesting (DEH) or opportunistic energy harvesting (OEH) mode. In DEH mode, the source sends dedicated energy-bearing signals and the jammer performs energy harvesting. In OEH mode, the source transmits an information-bearing signal to the destination. Meanwhile, using the harvested energy, the wireless-powered jammer transmits a jamming signal to confound the eavesdropper. Thanks to the FD capability, the jammer also harvests energy from the information-bearing signal that it overhears from the source. We study the complex energy accumulation and consumption procedure at the jammer by considering a practical finite-capacity energy storage, of which the long-term stationary distribution is characterized through applying a discrete-state Markov Chain. An alternative energy storage with infinite capacity is also studied to serve as an upper bound. We further derive closed-form expressions for two secrecy metrics, i.e., secrecy outage probability and probability of positive secrecy capacity. In addition, the impact of imperfect channel state information on the performance of our proposed protocol is also investigated. Numerical results validate all theoretical analyses and reveal the merits of the proposed AnJ protocol over its half-duplex counterpart.
In this letter, we consider a cooperative wireless network consisting of a source, multiple intermediate energy harvesting nodes, and a destination, in the presence of a passive eavesdropper. First, the intermediate nodes use the time switching-based relaying protocol to harvest energy from the source signal. Then, a pair out of intermediate nodes are selected as a relay and a jammer to transmit confidential and jamming signals to the destination and eavesdropper. Under these assumptions, we evaluate the system performance in terms of secrecy outage probability.
This paper explores the use of a full-duplex (FD) friendly jammer to secure the communication between a transmitter and a receiver in the presence of a passive eavesdropper. The friendly jammer is considered as a wireless-powered node without embedded power supply but can harvest energy from radio frequency (RF) signals, accumulate it in the storage, and use the harvested energy to perform the cooperative jamming (CJ). A novel CJ protocol termed accumulate-and-jam (AnJ) is proposed to improve the jammer efficiency, which splits the transmission blocks into dedicated energy harvesting (DEH) blocks and opportunistic energy harvesting (OEH) blocks. In DEH blocks, the transmitter transfers wireless power to replenish the jammer. In OEH blocks, the transmitter sends information to the receiver. Using the accumulated energy, the jammer transmits jamming signals to confound the eavesdropper. Mean-while, thanks to the FD capability, the jammer can continue to harvest energy from the signals overheard from the transmitter. Compared with the existing protocols using a wireless powered half-duplex (HD) jammer, the proposed design possesses the advantage of uninterrupted energy harvesting at the jammer. A closed-form expression for the secrecy outage probability of the considered system is derived. Numerical results show that our proposed AnJ protocol can significantly outperform its HD counterpart in terms of secrecy outage probability.
In this paper, the physical-layer security of a cooperative wireless system with multi-antenna full-duplex (FD) destination is examined. More specifically, we consider a cooperative transmission scenario in which a source communicates with a destination through a relay in the presence of an eavesdropper. In order to degrade the wiretap channel, the FD destination simultaneously transmits an interference signal towards the eavesdropper, while receiving information from the relay. A joint transmit and receive beamformer design is proposed to maximize the signal-to-interference-plus-noise ratio (SINR) at the destination, while guaranteeing that the SINR at the eavesdropper is below a certain threshold. We reformulate the optimization problem as a semidefinite relaxation problem in terms of a transmit beamforming matrix. To balance the performance and system complexity, we investigate suboptimum beamforming designs based on zero-forcing criterion. We derive exact closed-form expressions for the average secrecy rates of the proposed suboptimum designs. Our results reveal that optimum and suboptimum beamforming schemes along with friendly jamming significantly improve the secrecy performance. Moreover, simulation results demonstrate that the optimum scheme outperforms suboptimum schemes, especially in high transmit power regimes.
In this paper, we investigate the achievable secrecy rate in a relay channel where the source and the destination wish to keep the information confidential from an untrusted relay (potential eavesdropper). The relay has no energy supply, and harvests its required energy for relaying from its received signals. For radio-frequency (RF) Energy Harvesting (EH) at the relay, we adopt power splitting (PS) approach. We study the problem of achieving positive secrecy rates between the transmitter and the receiver while making use of an untrusted relay. Energy limitation at the relay makes the problem more interesting. Because, the relay must choose either to eavesdrop the signal to be able to decode or to harvest energy (from the information signal) to be able to forward the message. Our scheme to guarantee the secrecy uses cooperative jamming by either the destination or an extra jammer node. We derive the achievable secrecy rates for the compress-and-forward (CF) and amplify-and-forward (AF) relays for two different scenarios. First, we assume the destination and the jammer are two separate nodes. Then, we consider destination-assisted jamming. In addition, we let the relay to use both the sources and the jammers transmitted signals to harvest energy. Our numerical results show that our proposed schemes guarantee a positive secrecy rate by properly locating the jammer and allocating enough jamming power. However, for a given power budget (i.e., fixed total transmission and jamming power) there is an optimum amount for the jamming power.