In this paper, we consider a two-hop wireless system consisting of one source, one destination, one eavesdropper and multiple amplify-and-forward relays. A time-division duplex scheme is proposed that aims at minimizing the secrecy rate outage by selecting an optimal relay from the set of candidate relays. In the first time slot, the source transmits the information bearing signal, meanwhile the destination jams the eavesdropper. In the second slot, the selected relay forwards the received signals in amplify-and-forward fashion. Out of two hops, the eavesdropper can tap only the signal transmitted by the relay in the second hop. We obtain a closed-form expression of the end-to-end secrecy outage for instantaneous and statistical channel-state information of the eavesdropper. The analytical results suggest that the proposed destination-based jamming outperforms the conventional relay selection scheme without jamming. Monte Carlo simulations are performed to verify the analytical results.
In this paper, we consider a two-hop wireless system consisting of one source, one destination, one eavesdropper and multiple amplify-and-forward relays. A time-division duplex scheme is proposed that aims at minimizing the secrecy rate outage by selecting an optimal relay from the set of candidate relays. In the first time slot, the source transmits the information bearing signal, meanwhile the destination jams the eavesdropper. In the second slot, the selected relay forwards the received signals in amplify-and-forward fashion. Out of two hops, the eavesdropper can tap only the signal transmitted by the relay in the second hop. We obtain a closed-form expression of the end-to-end secrecy outage for instantaneous and statistical channel-state information of the eavesdropper. The analytical results suggest that the proposed destination-based jamming outperforms the conventional relay selection scheme without jamming. Monte Carlo simulations are performed to verify the analytical results.
In this paper, we consider a two-hop relay wireless network with one source, one destination, one eavesdropper and multiple half-duplex (HD) relays each having a finite buffer. We assume two cases of the eavesdropper's channel state information (CSI), i.e., the perfect CSI case where the instantaneous CSI of the eavesdropper channels are available, and the partial CSI case where only the average CSI of the eavesdropper channels are available. Cooperative jamming schemes are proposed for both eavesdropper's CSI cases, where two relays are selected in each hop, one is selected as a message relay and another as a jammer to transmit jamming signals to degrade the eavesdropper channel. The security performance in terms of the secrecy outage probability (SOP) is analyzed by simulation. We also make comparison between our proposed cooperative jamming schemes with the random jammer selection scheme. Results show that the proposed cooperative jamming scheme outperforms the random jammer selection scheme and the joint consideration of the buffer-aided relay selection and jamming can achieve better security performance.
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.
In this paper, we investigate secure communications in two-hop wireless relaying networks with one eavesdropper. To prevent the eavesdropper from intercepting the source message, the destination sends an intended jamming noise to the relay, which is referred to as cooperative jamming. This jamming noise helps protecting the source message from being captured reliably at the eavesdropper, while the destination cancels its self-intended noise. According to the channel information available at the destination, we derive three jamming power allocation strategies to minimize the outage probability of the secrecy rate. In addition, we derive analytic results quantifying the jamming power consumption of the proposed allocation methods.
A wireless network with one source, one destination, one eavesdropper, and multiple decode-and-forward relays is considered. A two-slot cooperative relaying scheme is proposed that targets at maximizing the secrecy rate. In the first slot, the source transmits the information bearing signal, and at the same time, it cooperates with the destination in jamming the eavesdropper without creating interference at the relay. In the second slot, one optimally selected relay retransmits the decoded source signal, and at the same time, that particular relay cooperates with the source to jam the eavesdropper without creating interference at the destination. Optimal relay selection and also optimal power allocation among the first/second slot data signal and jamming noise are proposed. It is shown that the secrecy rate of the proposed scheme scales with the total system powerP0and the number of available relaysKaccording to 1/2log2(1 +P0/8logK) - 1.6 bits/channel use . Although the proposed power allocation and relay selection assume global CSI available, the performance under imperfect relay CSI is also investigated. Also, the performance under distributed relay selection with limited feedback is demonstrated.
A wireless network with one source, one destination, one eavesdropper and multiple decode-and-forward (DF) relays is considered. A two-slot cooperative relaying scheme is proposed that targets at maximizing the secrecy rate. In the first slot, the source transmits the information bearing signal, and at the same time, it cooperates with the destination in jamming the eavesdropper without creating interference at the relay. In the second slot, one optimally selected relay retransmits the decoded source signal, and at the same time, it cooperates with the source to jam the eavesdropper without creating interference at the destination. For the beamforming, no eavesdropper channel information is required. Optimal relay selection and also optimal power allocation among the first/second slot data signal and jamming noise are proposed. It is shown that the system secrecy rate of the proposed scheme scales with the total system power, P0and the number of available relays, K, according to log2(1 + P0/8 log K) - 1.6252bps.
In this paper the cooperation of beam-forming and artificial noise (AN) in two-hop amplify-and- forward (AF) relaying system is proposed to enhance the security. we consider a half duplex AF relaying network with a multi-antenna source node and a destination in the presence of a passive eavesdropper.Since channel state information (CSI) of the eavesdropper is unknown, the AN transmitted by the source in the first phase and by the relays in the second phase is in all directions except the legitimate node one. As such two scenarios are considered here,: i) when all the relays amplify and forward the information source signal ii) when only the best relay is selected to amplify and forward the information source signal. The beam-former weights and the power allocation are obtained by solving an optimization problem. Results reveal that the proposed system can provide considerable improvements in terms of secrecy rate. It is also found that increasing the AN power, relative to the information signal power, will further improve the secrecy rate.