A distributed 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, in which relays help the source transmit to the destination while keeping the message as secret as possible from the eavesdropper. In the first slot, the source transmits a weighted combination of the information bearing signal and a noise signal. At the same time, the destination cooperates with the source in transmitting a noise signal with the purpose of confounding the eavesdropper. In the second slot, the `best' relay cooperates with the source to send a jamming signal along the null space of the destination channel. Optimal relay selection and also optimal power allocation among the first/second slot data signal and jamming noise is proposed. With the proposed transmission scheme, the system secrecy rate is shown to outperform the methods in literature and always benefits from increasing total power and larger number of relays.
A distributed 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, in which relays help the source transmit to the destination while keeping the message as secret as possible from the eavesdropper. In the first slot, the source transmits a weighted combination of the information bearing signal and a noise signal. At the same time, the destination cooperates with the source in transmitting a noise signal with the purpose of confounding the eavesdropper. In the second slot, the `best' relay cooperates with the source to send a jamming signal along the null space of the destination channel. Optimal relay selection and also optimal power allocation among the first/second slot data signal and jamming noise is proposed. With the proposed transmission scheme, the system secrecy rate is shown to outperform the methods in literature and always benefits from increasing total power and larger number of relays.
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.
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 distributed wireless network with one source, one destination, one eavesdropper and multiple Decode-and-Forward (DF) relays is investigated. A two-slot cooperative relaying scheme is considered, in which relays help the source transmit to the destination while keeping the message as secret as possible from the eavesdropper. To prevent the system becoming interference limited, a destination assisted jamming scheme is used, i.e., the destination transmits a jamming signal rather than listening to the source. Several relay selection methods are proposed to let the system benefit from increase of the number of relays. With the proposed transmission scheme, the system secrecy rate is shown to outperform the methods in literature and maintain a scaling law of the achievable secrecy rate of log2(1 + P0/8 log K) -1.6252, where K is the number of relays and P0is the total transmit power.
In a cooperative wireless network, we exploited node cooperation for achieving physical layer based security. In this paper, the case of one source-destination pair with the help of multiple cooperating nodes(relay nodes and jamming nodes) in the presence of one eavesdropper was considered to improve the performance of secure wireless communications. A novel cooperative scheme joint decode-and-forward and cooperative jamming(JDFCJ) was proposed. In this scheme, the relay nodes transmit a weighted version of the source signals and the jamming nodes just transmit a common weighted jamming signal to confound the eavesdropper. The novel system design is proposed to minimize the transmit power subject to a secrecy rate constraint. For JDFCJ, the optimal power allocation is obtained in closed-form in the condition of the complete nulling of jamming signals at the destination. The numerical evaluation of the transmit power results shows that the proposed scheme can significantly improve the performance of secure wireless communications, as compared to the DF scheme.
In this paper, the case of one source-destination pair with the help of multiple cooperating nodes in the presence of one eavesdropper was considered to improve the performance of secure wireless communications.A novel cooperative scheme decode-and-forward plus cooperative jamming(DFCJ) was proposed.In this scheme, the relay nodes transmit a weighted version of the source signals plus a common weighted jamming signal to confound the eavesdropper.For DFCJ, the optimal power allocation is obtained in closed-form in the condition of the complete nulling of jamming signals at the destination subject to a secrecy rate constraint.The numerical evaluation of the transmit power and the obtained secrecy rate results shows that the proposed scheme can significantly improve the performance of wireless physical layer security, as compared to the decodeand-forward(DF) scheme.
Physical (PHY) layer security approaches for wireless communications can prevent eavesdropping without upper layer data encryption. However, they are hampered by wireless channel conditions: absent feedback, they are typically feasible only when the source-destination channel is better than the source-eavesdropper channel. Node cooperation is a means to overcome this challenge and improve the performance of secure wireless communications. This paper addresses secure communications of one source-destination pair with the help of multiple cooperating relays in the presence of one or more eavesdroppers. Three cooperative schemes are considered: decode-and-forward (DF), amplify-and-forward (AF), and cooperative jamming (CJ). For these schemes, the relays transmit a weighted version of a reencoded noise-free message signal (for DF), a received noisy source signal (for AF), or a common jamming signal (for CJ). Novel system designs are proposed, consisting of the determination of relay weights and the allocation of transmit power, that maximize the achievable secrecy rate subject to a transmit power constraint, or, minimize the transmit power subject to a secrecy rate constraint. For DF in the presence of one eavesdropper, closed-form optimal solutions are derived for the relay weights. For other problems, since the optimal relay weights are difficult to obtain, several criteria are considered leading to suboptimal but simple solutions, i.e., the complete nulling of the message signals at all eavesdroppers (for DF and AF), or the complete nulling of jamming signal at the destination (for CJ). Based on the designed relay weights, for DF in the presence of multiple eavesdroppers, and for CJ in the presence of one eavesdropper, the optimal power allocation is obtained in closed-form; in all other cases the optimal power allocation is obtained via iterative algorithms. Numerical evaluation of the obtained secrecy rate and transmit power results show that the proposed design can significantly improve the performance of secure wireless communications.