This paper exploits physical layer network coding (PNC) and friendly jamming to improve their physical layer security in wireless two-hop cooperative communications, consisting of one source-destination pair with the help of multiple intermediate nodes in the presence of one eavesdropper. By sending a jamming signal carrying a random binary message from the selected jammer and utilizing the PNC at the selected relay node, the system can avoid the disadvantage of the friendly jamming to the source-relay channel and do good to the relay-destination channel, thereby achieving better secrecy rate. Assuming global channel state information available and memoryless adversaries, we seek to minimize the secrecy outage probability with the optimal relay and jammer selection. Numerical simulation results show that our schemes outperform the conventional approaches in wireless cooperative communications.
This paper exploits physical layer network coding (PNC) and friendly jamming to improve their physical layer security in wireless two-hop cooperative communications, consisting of one source-destination pair with the help of multiple intermediate nodes in the presence of one eavesdropper. By sending a jamming signal carrying a random binary message from the selected jammer and utilizing the PNC at the selected relay node, the system can avoid the disadvantage of the friendly jamming to the source-relay channel and do good to the relay-destination channel, thereby achieving better secrecy rate. Assuming global channel state information available and memoryless adversaries, we seek to minimize the secrecy outage probability with the optimal relay and jammer selection. Numerical simulation results show that our schemes outperform the conventional approaches in wireless cooperative communications.
In this paper, we investigate physical layer network coding (PNC) and destination assisted cooperative jamming (DACJ) for physical layer security in wireless sensor networks, in which there is one source, one destination, a cluster of intermediate nodes, and multiple eavesdroppers. Under the PNC protocol, the considered two-hop wireless sensor network implements a complete transmission process in two phases. In the first phase, through sending a jamming signal from the destination and exploiting the PNC at the relay, the relay decodes the exclusive-OR (XOR) performed form of the source and the jamming message. Therefore, the jamming signal can degrade the wire-tap channels without hampering the legitimate channel. In the second phase, the relay transmits the re-encoded message to the destination while eavesdroppers are out of work as they cannot extract information from the signal. Thus, the proposed design can significantly improve the performance of secure wireless communications. Meanwhile, the proposed schemes select one optimal node from the intermediate nodes and give an optimal solution of power allocation to maximize secrecy capacity. Numerical simulation results show that the proposed schemes have a better and more stable secrecy performance than the conventional schemes at the same power consumption.
In this paper, we investigate secure communication in two-hop cooperative relay network with physical layer network coding (PNC). By sending a jamming signal from the destination and exploiting the PNC at the relay, the relay decodes the exclusive-OR (XOR) performed message of the source message and the jamming. This process acts as the encryption of the source message at the relay with a random jamming sequence which can be subtracted only at the destination, so that it prevents the eavesdropper from intercepting the message. We derive the outage probability of the secure scheme with PNC and compare the performance with the cooperative scheme without jamming.
In this paper, the security of two-phase relaying system with multiple intermediate nodes in the presence of a malicious eavesdropper is investigated. To enhance the secrecy, a joint cooperative beamforming and jamming combined with relay and jammer selection is proposed. First, the source broadcasts its signal to the relays that are located close to source in a cluster, i.e., the source node uses a small amount of power to broadcast its message locally to other nodes of the cluster, while destination and the eavesdropper are located outside this cluster. In the second phase, two relays transmit re-encoded signal with optimal beamforming such that the secrecy rate is maximized. Simultaneously, two other intermediate nodes (which act as friendly jammers) transmit random jamming signals to degrade the eavesdropper’s channel. Our goal in this paper is to maximize the secrecy rate by applying different methods such as cooperative beamforming, cooperative jamming and relay and jammer selection. To avoid operational complexity, we consider the minimum number of intermediate nodes needed for relaying and jamming without losing the performance, i.e., achieving a non-zero secrecy rate. Cooperative beamforming with multiple relays demands high amount of information exchange and therefore increases the operational complexity. Thus, we aim to reduce the number of relays which take part in cooperative beamforming. Limiting the number of relays may have a bad effect on the coding gain which we compensate it with a proposed selection gain scheme. Numerical results demonstrate the advantage of our proposed scheme compared to the scheme with no cooperative jamming. The main contribution of this work is combining cooperative beamforming and jamming with relay and jammer selection to enhance the physical layer security.
In this paper, three different relay and jammers selection schemes are presented to improve the physical layer security of two-way cooperative networks in the presence of multiple cooperating and non-cooperating eavesdroppers. The presented selection schemes are; optimal selection scheme without jamming, optimal selection scheme with conventional jamming, and optimal selection scheme with controlled jamming. The proposed schemes select three intermediate nodes during two communication phases. In the first phase, a friendly jammer is selected to create intentional interference at the eavesdroppers' nodes. In the second phase, two relay nodes are selected; one node is selected to operate as a conventional relay and assists the sources to deliver their data to the corresponding destinations via a Decode-and-Forward (DF) strategy. While the other node behaves as a jammer node in order to confuse the eavesdroppers in this phase. The proposed schemes are analyzed in terms of ergodic secrecy rate and secrecy outage probability. The obtained results show that the jamming schemes outperform the non-jamming schemes in the eavesdroppers' environment. Moreover, cooperating eavesdroppers' further degrade system's secrecy performance than the non-cooperating ones. Finally, a comparison between relay and jammers selection schemes in both one-way and two-way cooperative networks is given in terms of both ergodic secrecy rate and secrecy outage probability metrics.
The broadcast nature of wireless communications makes the propagation medium vulnerable to security attacks such as eavesdropping and jamming from adversarial or unauthorized users. Applying physical layer secrecy approaches will enable the exchange of confidential messages over a wireless medium in the presence of unauthorized eavesdroppers, without using any secret keys. However, physical layer security approaches are typically feasible only when the source-eavesdropper channel is weaker than the source-destination channel. Cooperative jamming can be used to overcome this challenge and increase the secrecy rate. In this paper, the security of two-phase relaying system with multiple intermediate nodes and in the presence of an eavesdropper is investigated. To enhance the system secrecy rate, a joint cooperative beamforming and jamming combined with relay and jammer selections is proposed. In phase I, the source node broadcasts a signal to relays while three intermediate nodes (which act as jammers) help the source node by transmitting random jamming signals to confuse the eavesdropper. Since the friendly (cooperative) jammers create interference for both the intended relays and the eavesdropper, optimal beamforming is applied such that no interference is caused at two preselected desired relays (that are going to receive the confidential massage in phase I). In phase II, two preselected relays transmit the source message with beamforming coefficients such that the received signal at the eavesdropper is completely nulled out. Our goal in this paper is to minimize the received SNR at the eavesdropper while increasing it at the destination as much as possible by applying different methods such as cooperative beamforming, cooperative jamming and relay selection. To avoid operational complexity, we consider the minimum number of intermediate nodes that are necessary without losing the performance. Numerical results demonstrate the advantage of our proposed scheme compared with the scheme with no cooperative jamming.
This paper investigates the security at the physical layer of cooperative relay communications. Inspired by the principle of physical-layer network coding (PNC), we propose a new secure relaying scheme, namely secure PNC-based modify-and-forward (SPMF). In the proposed scheme, the relay node linearly combines the decoded data from the source node with an encrypted key before conveying the mixed data to the destination node. As both the linear PNC operation and encrypted key at the relay are unknown to the eavesdropper, the SPMF scheme provides a double security level in the system. Particularly, taking into account the practical scenario of the imperfect knowledge shared between the relay and destination, the secrecy outage probability (SOP) of the proposed SPMF scheme is analysed and evaluated in comparison with modify-and-forward, cooperative jamming, decode-and- forward and direct transmission schemes. The proposed scheme is shown to achieve a performance improvement of up to 3 dB when compared to the conventional schemes under imperfect knowledge of shared information between the nodes.