In this paper, two methods to improve the secrecy of cooperative transmissions using unshared jamming are investigated in which only the source and destination nodes know the jamming signals. The jamming signals are based on unique cipher keys obtained on the high layers. In the first proposed method (SJ protocol), a source combines its secrecy signal with its jamming signal using the power allocation strategy before broadcasting to the relay, destination and even eavesdropper nodes. In the second proposed method (DJ protocol), a source transmits its secrecy signal at the same time a destination transmits its jamming signal. For the secrecy performance evaluation, the asymptotic secrecy outage probability of the end-to-end achievable secrecy rate over flat and block Rayleigh fading channels are studied. Monte-Carlo results are presented to verify the theoretical analyses.
In this paper, two methods to improve the secrecy of cooperative transmissions using unshared jamming are investigated in which only the source and destination nodes know the jamming signals. The jamming signals are based on unique cipher keys obtained on the high layers. In the first proposed method (SJ protocol), a source combines its secrecy signal with its jamming signal using the power allocation strategy before broadcasting to the relay, destination and even eavesdropper nodes. In the second proposed method (DJ protocol), a source transmits its secrecy signal at the same time a destination transmits its jamming signal. For the secrecy performance evaluation, the asymptotic secrecy outage probability of the end-to-end achievable secrecy rate over flat and block Rayleigh fading channels are studied. Monte-Carlo results are presented to verify the theoretical analyses.
In wireless communication, the secrecy of data transmission is an important objective, and especially when eavesdropper nodes are near source nodes. In this case, eavesdropper nodes can wiretap easily any information from the source nodes. In this paper, an approach method to improve secrecy cooperation transmissions using combined signals is investigated in which data and jamming signals are combined at a source node based on power allocation strategy. The secrecy system performances are evaluated using asymptotic secrecy outage probabilities of end-to-end achievable secrecy rates over flat and block Rayleigh fading channels. Monte-Carlo simulation results are presented to verify the theoretical analyses. The main contributions of the proposed protocol are as follows. First, the jamming signals at the source node are secret against a relay and an eavesdropper node. Second, an amplify-and-forward method is applied so the relay cannot know the secrecy signal along with the jamming signals. Third, by transmitting the jamming signals from the source node, the proposed protocol prevents wiretapping by nearby eavesdropper. Finally, the asymptotic analysis is valid with the simulation result evaluating the secrecy performance of the proposed protocol.
The open nature of the wireless networks makes them vulnerable to the eavesdropper attacks. Cooperative relay transmission is a popular method to prevent the attacks of the illegal nodes. This research proposes a cooperative jamming protocol to enhance the physical layer in wireless cooperative networks, where the destination sends a jamming signal to the eavesdropper node to degrade its channel capacity. Simulations of the secrecy performance metrics in terms of the secrecy capacity and secrecy outage probability are presented and discussed to measure the security level of the proposed jamming protocol. In this paper, different channels namely Rician fading, Rayleigh fading, and Additive White Gaussian Noise (AWGN) channels are investigated in the half-duplex two-way relaying system to obtain the maximum secrecy performance. Based on the results, the highest secrecy capacity is achieved by using the Rician fading channel for transmission from the source to the destination and using the Rayleigh channel as the jamming link to degrade the eavesdropper capacity.
The open nature of the wireless networks makes them vulnerable to the eavesdropper attacks. Cooperative relay transmission is a popular method to prevent the attacks of the illegal nodes. This research proposes a cooperative jamming protocol to enhance the physical layer in wireless cooperative networks, where the destination sends a jamming signal to the eavesdropper node to degrade its channel capacity. Simulations of the secrecy performance metrics in terms of the secrecy capacity and secrecy outage probability are presented and discussed to measure the security level of the proposed jamming protocol. In this paper, different channels namely Rician fading, Rayleigh fading, and Additive White Gaussian Noise (AWGN) channels are investigated in the half-duplex two-way relaying system to obtain the maximum secrecy performance. Based on the results, the highest secrecy capacity is achieved by using the Rician fading channel for transmission from the source to the destination and using the Rayleigh channel as the jamming link to degrade the eavesdropper capacity.
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.
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.
In this paper, we investigate secrecy communications in two-hop wireless relaying networks which consist of one source, one amplify-and-forward (AF) relay, one legitimate destination, and one eavesdropper. To prevent the eavesdropper from intercepting the source message, we make the destination send the intended noise to the AF relay during the first phase. This is referred to as cooperative jamming. According to the channel information at the destination, we address two types of jamming power allocation; (i) rate-optimal power allocation and (ii) outage-optimal power allocation. More specifically, without the instantaneous channel knowledge for the eavesdropper side, the outage probability of the secrecy rate is minimized with respect to the intended noise power level. We show that the outage-optimal allocation gives almost the same outage probability as the rateoptimal one. In addition, the jamming power consumption can be significantly reduced compared to the fixed and rate-optimal power allocation methods.