In this paper, we consider a two-way relay secure communications scheme where the two sources can only communicate through untrusted amplify-and-forward relays in the presence of jammers. We propose several schemes to optimize the secure sum-rate of the network including the optimal exhaustive search scheme (Best R) and other sub-optimal schemes including selecting the relay with the maximum of the minimum channel gain to two sources (MaxMin Gain) and a random relay (Random R) considering two modes of uniform and different jamming powers. Furthermore, to investigate the effect of number relays, we also analyzed secrecy rates based on three different schemes and two modes. Finally, the simulation results verify the properties and efficiency of the proposed scheme.
In this paper, we consider a two-way relay secure communications scheme where the two sources can only communicate through untrusted amplify-and-forward relays in the presence of jammers. We propose several schemes to optimize the secure sum-rate of the network including the optimal exhaustive search scheme (Best R) and other sub-optimal schemes including selecting the relay with the maximum of the minimum channel gain to two sources (MaxMin Gain) and a random relay (Random R) considering two modes of uniform and different jamming powers. Furthermore, to investigate the effect of number relays, we also analyzed secrecy rates based on three different schemes and two modes. Finally, the simulation results verify the properties and efficiency of the proposed scheme.
In this paper, we investigate joint relay and jammer selection in two-way cooperative networks, consisting of two sources, one eavesdropper, and a number of intermediate nodes, with secrecy constraints. Specifically, the proposed schemes select two or three intermediate nodes to enhance security against the malicious eavesdropper. The first selected node operates in the conventional relay mode and assists the two sources to exchange data with each other in the amplify-and-forward protocol. The second and third selected nodes are used in different communication phases as jammers in order to create intentional interference upon the eavesdropper. We find that in a scenario where the relay and jamming nodes are randomly and sparsely distributed, the proposed schemes with cooperative jamming outperform the conventional non-jamming schemes within a certain transmitted power range. We also find that, in a scenario where the intermediate nodes gather as a close cluster, the cooperative jamming schemes may be less effective than their non-jamming counterparts. Therefore, we introduce a hybrid scheme to switch between jamming and non-jamming modes. Simulation results validate our theoretical analysis that the hybrid switching scheme further improves the secrecy rate.
In this paper, we consider a two-way relay network where two sources can communicate only through an unauthenticated intermediate relay node. We investigate secure communications of this two-way relay scenario using physical layer security. Specifically, we treat the relay node as an eavesdropper from whom the information transmitted by the sources needs to be kept secret, despite the fact that its cooperation in relaying this information is essential. We first find that a non-zero secrecy rate is indeed achievable in this two-way relay network even without external jammers. Further still, with the help of friendly jammers who can transmit jamming signals to distract the malicious relay, a positive gain of the secrecy rate can be realized. In order to obtain the maximum secrecy rate, we define and then analyze an optimization problem. Finally, an optimal solution of jamming power allocation is provided for the system with friendly jammers.
In this paper, we consider a two-way relay system where the two sources can only communicate through an untrusted intermediate relay and investigate the physical layer security issue in this two-way untrusted relay scenario. Specifically, we regard the intermediate relay as an eavesdropper from which the information transmitted by the sources needs to be kept confidential, despite the fact that its cooperation in relaying this information is essential. We first indicate that a nonzero secrecy rate is indeed achievable in this two-way untrusted relay system even without the help of external friendly jammers. As for the system with friendly jammers, after further analysis, we can obtain the secrecy rate of the sources can be effectively improved by utilizing proper jamming power from the friendly jammers. Then, we formulate a Stackelberg game between the sources and the friendly jammers as a power control scheme to achieve the optimized secrecy rate of the sources, in which the sources are treated as the sole buyer and the friendly jammers are the sellers. In addition, the optimal solutions of the jamming power and the asking prices are given, and a distributed updating algorithm to obtain the Stackelberg equilibrium is provided for the proposed game. Finally, the simulation results verify the properties and efficiency of the proposed Stackelberg-game-based scheme.
In this paper, we investigate joint relay and jammer selection in two-way cooperative networks, consisting of two sources, a number of intermediate nodes, and one eavesdropper, with secrecy constraints. Specifically, the proposed algorithms select two or three intermediate nodes to enhance security against the malicious eavesdropper. The first selected node operates in the conventional relay mode and assists the sources to deliver their data to the corresponding destinations via the amplify-and-forward protocol. The second and third nodes are used in different communication phases as jammers in order to create intentional interference upon the eavesdropper node. Firstly, we find that in a topology where the relay and jamming nodes are randomly and sparsely distributed, the proposed schemes with cooperative jamming outperforms the conventional non-jamming schemes within a certain transmitted power regime. We also find that, in the scenario in which the intermediate nodes gather as a close cluster, the jamming schemes may be less effective than their non-jamming counterparts. Therefore, we introduce a hybrid scheme to switch between jamming and non-jamming modes. Simulation results validate our theoretical analysis that the hybrid switching scheme further improves the secrecy rate.
In this paper, we propose a two-way secure communication scheme where two transceivers exchange confidential messages via a wireless-powered untrusted amplify-and-forward relay in the presence of an external jammer. We take into account both friendly jamming (FJ) and Gaussian noise jamming (GNJ) scenarios. Based on the time switching (TS) architecture at the relay, the data transmission is done in three phases. In the first phase, both the energy-starved nodes, the untrustworthy relay and the jammer, are charged by noninformation radio frequency (RF) signals from the sources. In the second phase, the two sources send their information signals and concurrently, the jammer transmits artificial noise to confuse the curious relay. Finally, the third phase is dedicated to forward a scaled version of the received signal from the relay to the sources. For the proposed secure transmission schemes, we derive new closed-form lower-bound expressions for the ergodic secrecy sum rate (ESSR) in the high signal-to-noise ratio (SNR) regime. We further analyze the asymptotic ESSR to determine the key parameters; the high SNR slope and the high SNR power offset of the jamming based scenarios. To highlight the performance advantage of the proposed FJ, we also examine the scenario of without jamming (WoJ). Finally, numerical examples and discussions are provided to acquire some engineering insights, and to demonstrate the impacts of different system parameters on the secrecy performance of the considered communication scenarios. The numerical results illustrate that the proposed FJ significantly outperforms the traditional one-way communication and the constellation rotation (CR) approach, as well as our proposed benchmarks, the two-way WoJ and GNJ scenarios.
In this paper, we investigate joint relay and jammer selection in two-way cooperative networks, consisting of two sources, a number of intermediate nodes, and one eavesdropper, with the constraints of physical-layer security. Specifically, the proposed algorithms select two or three intermediate nodes to enhance security against the malicious eavesdropper. The first selected node operates in the conventional relay mode and assists the sources to deliver their data to the corresponding destinations using an amplify-and-forward protocol. The second and third nodes are used in different communication phases as jammers in order to create intentional interference upon the malicious eavesdropper. First, we find that in a topology where the intermediate nodes are randomly and sparsely distributed, the proposed schemes with cooperative jamming outperform the conventional nonjamming schemes within a certain transmitted power regime. We also find that, in the scenario where the intermediate nodes gather as a close cluster, the jamming schemes may be less effective than their nonjamming counterparts. Therefore, we introduce a hybrid scheme to switch between jamming and nonjamming modes. Simulation results validate our theoretical analysis and show that the hybrid switching scheme further improves the secrecy rate.