This letter studies the physical-layer security of a full-duplex (FD) multiple-input multiple-output relay channel. A legitimate source node (Alice) communicates with her destination node (Bob) through an FD relay node in the presence of a cooperative FD jammer and a potential eavesdropper (Eve). The cooperative jammer is assumed to be an FD node that is solely charged by the ambient radio-frequency transmissions. We investigate the self-energy recycling at the cooperative jammer and derive a sufficient condition for the cooperative jammer to operate as a node with reliable energy supply. Without knowing the eavesdropper's channel state information at the legitimate nodes, we propose a precoded artificial-noise (AN) injection scheme to secure the legitimate transmissions. The numerical results demonstrate that our proposed AN-aided secure scheme achieves a significant average secrecy rate improvement compared with the case of no cooperative jammer.
This letter studies the physical-layer security of a full-duplex (FD) multiple-input multiple-output relay channel. A legitimate source node (Alice) communicates with her destination node (Bob) through an FD relay node in the presence of a cooperative FD jammer and a potential eavesdropper (Eve). The cooperative jammer is assumed to be an FD node that is solely charged by the ambient radio-frequency transmissions. We investigate the self-energy recycling at the cooperative jammer and derive a sufficient condition for the cooperative jammer to operate as a node with reliable energy supply. Without knowing the eavesdropper's channel state information at the legitimate nodes, we propose a precoded artificial-noise (AN) injection scheme to secure the legitimate transmissions. The numerical results demonstrate that our proposed AN-aided secure scheme achieves a significant average secrecy rate improvement compared with the case of no cooperative jammer.
We investigate the physical-layer security of a buffer-aided multiple-input multiple-output relay channel. The wireless network under investigation is composed of one legitimate source node (Alice), one legitimate half-duplex relay node, and one legitimate destination node (Bob). Alice communicates with both relay and Bob in the presence of a potential passive multi-antenna eavesdropper (Eve). Without knowing the instantaneous eavesdropper's channel state information at the legitimate nodes, we propose a precoded artificial-noise injection scheme to enhance the security of the legitimate transmissions. The relay is equipped with a finite buffer to store the unsuccessfully decoded packets at Bob. We analyze the Markov chain of the relay's queue and derive its steady-state distributions. Our optimization problem is formulated such that the average end-to-end secure throughput is maximized under the secrecy outage probability constraint on the Alice-relay link. Our numerical results demonstrate that our proposed buffer-aided relaying scheme achieves a significant improvement in the secure throughput compared with the conventional bufferless relaying scheme, where the time slot is divided equally between the source and the relay for their data transmissions.
This letter investigates the physical layer security in a wireless cooperative network where communication is assisted by a full-duplex (FD) untrusted relay in the presence of multiple external eavesdroppers. A cluster-based colluding eavesdropping setting is considered, where illegitimate nodes with common interests are grouped in a cluster. In order to confuse the different eavesdropping clusters, we consider artificial-noise-aided beamforming at the source node. Moreover, FD relay jamming is adopted to improve the system's security. To maintain secure communications against the untrusted relay node, a FD destination jamming scheme is adopted. Our proposed scheme is designed based on the channel state information of the legitimate nodes only. Numerical results show that the optimal power allocation factor between data and artificial noise depends on the total number of antennas of the different colluding eavesdropping clusters.
We investigate the physical layer security of a wireless cooperative network where communication between Alice and Bob is assisted by a full-duplex (FD) untrusted relay, Ray, in the presence of multiple external eavesdroppers, Eves. A cluster-based colluding eavesdropping setting is considered, where illegitimate nodes with common interests are grouped in a cluster. To confuse the different eavesdropping clusters, we employ artificial-noise (AN) aided beamforming at the source node. Moreover, FD relay jamming is used to improve the system's security. To maintain secure communications against the untrusted relay node, an FD destination jamming scheme is adopted. Our proposed scheme is designed based on the channel state information of the legitimate nodes only. We optimize the transmit power allocation factors between data and AN signals, the data and AN precoders at Alice, the AN precoder at Bob, and the data and AN precoders at Ray. Numerical results show that the optimal power allocation factor between data and AN depends on the total number of antennas of the different colluding eavesdropping clusters.
Non-orthogonal multiple access (NOMA) and wireless energy harvesting are two promising technologies for improving spectral efficiency and energy efficiency, respectively. In this paper, we study the physical layer security of a wireless-powered full-duplex (FD) relay-aided cooperative NOMA system. In particular, the source is wiretapped by an eavesdropper, and the FD relay assists the transmission from the source to a near user and a far user with self-energy recycling. To enhance the security performance of the system, we propose an artificial noise (AN)-aided cooperative transmission scheme, in which the relay emits a jamming signal to confuse the eavesdropper while receiving the signal from the source. For the proposed scheme, the ergodic secrecy sum rate (ESSR) is derived to characterize the secrecy performance and a lower bound of ESSR is obtained. Finally, numerical results verify the accuracy of the theoretical analysis of the proposed AN-aided secure transmission scheme. The superiority of the proposed scheme is also demonstrated since this scheme can achieve better secrecy performance, compared to the conventional cooperative NOMA scheme.
In this paper, we investigate an artificial-noise (AN) aided secure transmission for non-orthogonal multiple access (NOMA) full-duplex (FD) relay network. We propose a novel joint NOMA and AN-aided full-duplex relay (NOMA-ANFDR) scheme to enhance the physical security. In this scheme, the optimal power allocation between the information and the AN signal is determined such that the capacity of the two end-to-end (i.e., two source-relay-destination pairs) channel are maximized to ensure the highest quality of cooperative transmission. To fully examine the benefits of the NOMA-ANFDR scheme, we derive a new closed-form expression for the secrecy outage probability.We show that the NOMA-ANFDR scheme significantly outperforms the joint NOMA and AN in half-duplex relay (NOMA-ANHDR) scheme as well as the NOMA-HDR scheme in terms of minimum secrecy outage probability and effect secrecy throughout. This result indicates that adopting the joint of FD and AN technique at relays can effectively enhance the physical layer secrecy performance in the NOMA cooperative network.
In Rayleigh fading channels, to enhance the secrecy performance of wireless communication systems and efficiently disturb the interception of eavesdroppers, the multiple-antenna source node utilizes the artificial noise aided precoding (ANP) strategy with imperfect channel state information to emit the confidential information and the artificial noise simultaneously. Besides, the two-antenna decode-and-forward relay node applies the full-duplex (FD) relaying protocol, and the destination node which contains multiple antennas adopts the maximum ratio combining technique. Taking into account the existence of self-interference at the relay, the closed-form expression of approximate ergodic achievable secrecy rate (EASR) for any value of antenna number and that of exact EASR in the case of large-scale antenna array are derived, respectively. To extract more distinct insights from the considered system and hence obtain some simple and meaningful conclusions, the asymptotic performance analyses in two different asymptotic cases are studied. The numerical simulations validate the correctness of our theoretical derivation and analysis, which indicates that the ANP scheme combined with the FD relaying can achieve considerable secrecy performance.