In this paper, we consider the multi-channel power optimization to enhance security for a full-duplex (FD) transmission pair. The FD-enabled concurrent transmissions between the users, on one hand, induce self-interference at their own receivers, and on the other hand, act as friendly jamming to degrade the eavesdropping for the other. To elaborate on such a tradeoff for secrecy maximization, we investigate the power allocation problem from both centralized and distributed perspectives. For the centralized approach, we intend to maximize users' sum secrecy rate. The non-concave problem is tackled by the difference-of- two-concave-functions programming, where the local optimal is obtained by iteratively solving a series of concave problems. For the distributed approach, we formulate the secrecy rate competition between the users as a game. The Nash equilibrium of the game is then achieved by the users' best-response iterations. In particular, by leveraging the theory of variational inequality, we derive the conditions for the equilibrium to be unique. Finally, we present simulation results that verify our theoretical analysis. Also, it is demonstrated that, for the security performance of FD and half- duplex transmissions, one may outperform the other depending on the self-interference cancellation.
In this paper, we consider the multi-channel power optimization to enhance security for a full-duplex (FD) transmission pair. The FD-enabled concurrent transmissions between the users, on one hand, induce self-interference at their own receivers, and on the other hand, act as friendly jamming to degrade the eavesdropping for the other. To elaborate on such a tradeoff for secrecy maximization, we investigate the power allocation problem from both centralized and distributed perspectives. For the centralized approach, we intend to maximize users' sum secrecy rate. The non-concave problem is tackled by the difference-of- two-concave-functions programming, where the local optimal is obtained by iteratively solving a series of concave problems. For the distributed approach, we formulate the secrecy rate competition between the users as a game. The Nash equilibrium of the game is then achieved by the users' best-response iterations. In particular, by leveraging the theory of variational inequality, we derive the conditions for the equilibrium to be unique. Finally, we present simulation results that verify our theoretical analysis. Also, it is demonstrated that, for the security performance of FD and half- duplex transmissions, one may outperform the other depending on the self-interference cancellation.
In this paper, we consider the physical layer security issue for the multi-channel full-duplex (FD) communications in the presence of eavesdroppers. There co-exist multiple FD pairs, where the two users in each pair perform bi-directional transmissions. The secure communication is then challenged by the users' self-interference, external interference from other pairs, and threats from the eavesdroppers. We investigate the problem from a distributed perspective and formulate the problem as a non-cooperative game, where each user optimizes their power allocation over the channels to maximize their own secrecy rate. Confirming the existence of the Nash equilibrium, we introduce an equivalent variational inequality (VI) formulation to derive the sufficient condition for the equilibrium to be unique. We then develop the iterative security-aware water-filling (ISWF) algorithm that can be implemented at each individual user in a distributed manner and prove that the condition for the unique equilibrium also claims the convergence of ISWF algorithm. Furthermore, we extend our formulation to the heterogeneous cases that there co-exist FD and half-duplex users with different security requirements in the networks, and demonstrate that they can all be covered as special cases under our formulated VI framework. Finally, we present simulation results to validate our theoretical findings.
In this paper, we examine the use of a friendly full-duplex (FD) relay to increase the secrecy rate over a fading channel between the legitimate source and the destination in the presence of residual self-interference (SI) and eavesdropper. In particular, we consider two different protocols based on the FD capability of relay: 1) FD transmission (FDT), in which the FD-Relay receives and sends data concurrently; 2) FD-Relay with jamming (FDJ), where first, the FD-Relay simultaneously receives data and sends jamming to the eavesdropper; then, it forwards the data, while the source jams the eavesdropper. We first develop the secrecy rate expressions for half-duplex transmission (HDT), half-duplex with jamming (HDJ), FDT, and FDJ relaying protocols, and then use them to derive their performance properties in terms of the channel gains between nodes, eavesdropper types, and more importantly, the SI level in FD-Relay. We further investigate the non-convex power allocation problems for the developed FDT and FDJ to maximize the secrecy rate under the power constraints. In particular, we develop an efficient iterative algorithm based on the difference-of-two-concave-functions programming. Analytical and simulation results show the strong influence of SI level on the achieved secrecy rate of the FDT and the FDJ. For sufficiently low SI, FDT achieves a much higher secrecy rate than FDJ, HDJ, and HDT. However, for higher SI, FDJ becomes more effective in enhancing the achieved secrecy rate. The results also indicate that adaptive power allocation can significantly improve the performance and confirm that the proposed FDT and FDJ outperform the HDT and the HDJ.
Security is an issue of paramount importance, yet is it a significant challenge for wireless communications, which becomes more intricate when facing a full duplex (FD) active eavesdropper capable of performing eavesdropping and jamming simultaneously. In this paper, we investigate the physical layer security issue in the presence of an FD active eavesdropper, who launches jamming attacks to further improve the eavesdropping. The jamming, however, also results in self-interference at the eavesdropper itself. This security problem is formulated within a hierarchical game framework where the eavesdropper acts as the leader and the legitimate user is the follower. In particular, we first investigate the follower's secrecy rate maximization problem and derive the optimal legitimate transmission strategy. Then, the leader's wiretap rate maximization is expressed as a mathematical program with equilibrium constraints (MPEC). Leveraging the concavity of the follower's problem, we transform the MPEC problem into a single-level optimization and obtain the jamming power allocation strategy by applying the primal-dual interior-point method. Moreover, we analyze the situations where only partial channel state information is available at the legitimate user and the corresponding impacts on the game. Finally, we present extensive simulation results to validate our theoretical analysis.
In this paper, we investigate the performance of artificial noise assisted secure communication in the presence of a full-duplex active eavesdropper who can simultaneously perform eavesdropping and jamming. An approximate closed-form expression for the secrecy rate is derived. With this result, we obtain a new result for the optimal power allocation factor maximizing the secrecy rate, and analyze the impact of self-interference coefficient and jamming power on it. We further consider a more practical scenario where the legitimate user aims to maintain a given target data rate and uses all remaining power for artificial noise (AN) to interfere with the eavesdropper. While the eavesdropper tries to compel the transmitter to reduce the AN by sending jamming signals to the legitimate receiver. To solve this conflict, we introduce a power cost parameter to describe the impact of jamming on the eavesdropper itself and then formulate a game-theoretic framework. We also derive the closed-form equilibrium solutions for both sides. These results show the optimal jamming strategy of the eavesdropper and provide insights into the low bound secrecy performance. Finally, simulation results are provided to verify our analytical results.
In this paper we address a sum secrecy rate maximization problem for a multi-carrier and MIMO communication system. We consider the case that the receiver is capable of full-duplex (FD) operation and simultaneously sends jamming signal to a potential eavesdropper. In particular, we simultaneously take advantage of the spatial and frequency diversity in the system in order to obtain a higher level of security in the physical layer. Due to the non-convex nature of the resulting mathematical problem, we propose an iterative solution with a guaranteed convergence, based on block coordinate descent method, by re-structuring our problem as a separately convex program. Moreover, for the special case that the transmitter is equipped with a single antenna, an optimal transmit power allocation strategy is obtained analytically, assuming a known jamming strategy. We also study a FD bidirectional secure communication system, where the jamming power can be reused to enhance the sum secrecy rate. The performance of the proposed design is then numerically evaluated compared to the other design strategies, and under different system assumptions.
This paper studies secrecy rate optimization in a wireless network with a single-antenna source, a multi-antenna destination and a multi-antenna eavesdropper. This is an unfavorable scenario for secrecy performance as the system is interference-limited. In the literature, assuming that the receiver operates in half duplex (HD) mode, the aforementioned problem has been addressed via use of cooperating nodes who act as jammers to confound the eavesdropper. This paper investigates an alternative solution, which assumes the availability of a full duplex (FD) receiver. In particular, while receiving data, the receiver transmits jamming noise to degrade the eavesdropper channel. The proposed self-protection scheme eliminates the need for external helpers and provides system robustness. For the case in which global channel state information is available, we aim to design the optimal jamming covariance matrix that maximizes the secrecy rate and mitigates loop interference associated with the FD operation. We consider both fixed and optimal linear receiver design at the destination, and show that the optimal jamming covariance matrix is rank-1, and can be found via an efficient 1-D search. For the case in which only statistical information on the eavesdropper channel is available, the optimal power allocation is studied in terms of ergodic and outage secrecy rates. Simulation results verify the analysis and demonstrate substantial performance gain over conventional HD operation at the destination.