Exploring a cooperative node as a friendly jammer is an effective means of providing secure communication between a source-destination pair in the presence of an eavesdropper. In this work, we consider the use of a wireless-powered friendly jammer. Without relying on external energy supply, the friendly jammer is powered by the source node via wireless power transfer. We apply a simple time-switching protocol where the power transfer and jammer-assisted secure transmission occur in different time blocks. By investigating the long-term behavior of the communication protocol, we derive a closed-form expression of the throughput. We further optimize the jamming power and the rate parameters for maximizing the throughput subject to a secrecy outage probability constraint.
Exploring a cooperative node as a friendly jammer is an effective means of providing secure communication between a source-destination pair in the presence of an eavesdropper. In this work, we consider the use of a wireless-powered friendly jammer. Without relying on external energy supply, the friendly jammer is powered by the source node via wireless power transfer. We apply a simple time-switching protocol where the power transfer and jammer-assisted secure transmission occur in different time blocks. By investigating the long-term behavior of the communication protocol, we derive a closed-form expression of the throughput. We further optimize the jamming power and the rate parameters for maximizing the throughput subject to a secrecy outage probability constraint.
In this paper, we propose using a wireless-powered friendly jammer to enable secure communication between a source node and destination node, in the presence of an eavesdropper. We consider a two-phase communication protocol with fixed-rate transmission. In the first phase, wireless power transfer is conducted from the source to the jammer. In the second phase, the source transmits the information-bearing signal under the protection of a jamming signal sent by the jammer using the harvested energy in the first phase. We analytically characterize the long-term behavior of the proposed protocol and derive a closed-form expression for the throughput. We further optimize the rate parameters for maximizing the throughput subject to a secrecy outage probability constraint. Our analytical results show that the throughput performance differs significantly between the single-antenna jammer case and the multiantenna jammer case. For instance, as the source transmit power increases, the throughput quickly reaches an upper bound with single-antenna jammer, while the throughput grows unbounded with multiantenna jammer. Our numerical results also validate the derived analytical results.
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, we addressed improving the physical layer security (PLS) of an energy harvest- ing (EH)-based wireless network composed of a source node, which is operated by the harvested energy from the power beacon and sends secure information to a destination in the presence of an eavesdropper and a cooperative jammer (CJ). In particular, we provided an explicit transmit design for minimizing the secrecy outage probability (SOP), subject to a minimum secrecy rate constraint. The results show that support from a friendly jammer can significantly improve the reliabil- ity and security performance of the system. Addition- ally, we described the effects of particular factors on the optimal possible temporal distribution between informa- tion transmission and energy harvesting. As a result, when considering the SOP, we concluded that there ex- ists an optimal value of the time switching factor for the system to function well. The analytical formulas were verified by Monte Carlo simulation.
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 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.
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.