In this letter, we consider a non-orthogonal multiple access (NOMA) network with a half-duplex (HD) decode-and-forward (DF) relay to improve physical layer security (PLS) of two users. Two legitimate users of U1 and U2 are far from the multi-antenna base station (BS). Thus, a relay with multi-antenna is used to enhance communication and obtain diversity gain. In the first stage, the BS transmits the superimposed signal to the relay via NOMA. Meanwhile, U1 generates the jamming signal to the eavesdropper (Eve). In the second stage, the relay forwards the signal to two users while the BS transmits the jamming signal to disrupt the eavesdropping. It is assumed that the Eve has strong eavesdropping ability. Thus, we need to introduce jamming to guarantee security. Furthermore, we use U1 instead of a full-duplex (FD) relay to send the jamming signal in the first stage to avoid self-interference. To measure the secrecy performance, a closed-form expression of secrecy outage probability (SOP) is derived for the two users. Simulation results are provided to verify the correctness of the proposed scheme.
In this letter, we consider a non-orthogonal multiple access (NOMA) network with a half-duplex (HD) decode-and-forward (DF) relay to improve physical layer security (PLS) of two users. Two legitimate users of U1 and U2 are far from the multi-antenna base station (BS). Thus, a relay with multi-antenna is used to enhance communication and obtain diversity gain. In the first stage, the BS transmits the superimposed signal to the relay via NOMA. Meanwhile, U1 generates the jamming signal to the eavesdropper (Eve). In the second stage, the relay forwards the signal to two users while the BS transmits the jamming signal to disrupt the eavesdropping. It is assumed that the Eve has strong eavesdropping ability. Thus, we need to introduce jamming to guarantee security. Furthermore, we use U1 instead of a full-duplex (FD) relay to send the jamming signal in the first stage to avoid self-interference. To measure the secrecy performance, a closed-form expression of secrecy outage probability (SOP) is derived for the two users. Simulation results are provided to verify the correctness of the proposed scheme.
Non-orthogonal multiple access (NOMA) is an important technology for the forthcoming 5 G and beyond. However, its privacy often suffers from adversarial eavesdropping, especially for the users with higher transmit power. In this paper, we propose a jamming-aided secure transmission scheme for cooperative NOMA networks with a full-duplex (FD) relay. In this scheme, two pairs of users perform secure transmission with the help of a decode-forward (DF) relay, which forwards information and generates artificial jamming to counteract eavesdropping. The precoding vectors are designed to zero-force the artificial jamming at legal receivers. Then, the channel statistics are calculated, based on which the secrecy rates of legitimate signals are analyzed and the expressions of secrecy outage probability (SOP) are derived. Furthermore, three benchmark schemes are also presented with their performance analyzed to verify the advantage of the proposed scheme. Simulation results show the accuracy of our analysis, and demonstrate that the proposed scheme can effectively reduce the SOP and improve the effective secrecy throughput via artificial jamming and FD relaying.
In a downlink non-orthogonal multiple access (NOMA) system, the reliable transmission of cell-edge users cannot be guaranteed due to severe channel fading. On the other hand, the presence of eavesdroppers can severely threaten the secure transmission due to the open nature of wireless channel. Thus, a two-user NOMA system assisted by a multi-antenna decode-and-forward relay is considered in this paper, and a two-stage jamming scheme, full-duplex-jamming (FDJam), is proposed to ensure the secure transmission of NOMA users. In the FDJam scheme, using full-duplex, the relay transmits the jamming signal to the eavesdropper while receiving confidential messages in the first stage, and the base station generates the jamming signal in the second stage. Furthermore, we eliminate the self-interference and the jamming signal at the relay and the legitimate node, respectively, through relay beamforming. To measure the secrecy performance, analytical expressions for secrecy outage probability (SOP) are derived for both the cell-center and cell-edge users, and the asymptotic SOP analysis at high transmit power is presented as well. Moreover, two benchmark schemes, half-duplex-jamming and full-duplex-no-jamming, are also considered. Simulation results are presented to show the accuracy of the analytical expressions and the effectiveness of the proposed scheme.
In a downlink non-orthogonal multiple access (NOMA) system, the reliable transmission of cell-edge users cannot be guaranteed. On the other hand, the presence of eavesdroppers can severely threaten the secure transmission. Thus, a two-user NOMA system assisted by a multi-antenna decode-and-forward (DF) relay is considered in this paper, and a two-stage jamming scheme, FDJam, is proposed to ensure the secure transmission of NOMA users. In the FDJam scheme, using full-duplex (FD), the relay transmits the jamming signal to the eavesdropper while receiving confidential messages in the first stage, and the base station (BS) generates the jamming signal in the second stage. Furthermore, we eliminate the self-interference and the jamming signal at the relay and the legitimate node, respectively, through relay beamforming. To measure the secrecy performance, analytical expressions for secrecy outage probability (SOP) are derived. Simulation results are presented to show the effectiveness of the proposed scheme.
Non-orthogonal multiple access (NOMA) is an important technology for the forthcoming 5G and beyond. However, its privacy often suffers from adversarial eavesdropping, especially for the users with higher transmit power. In this paper, we propose a jamming-aided secure transmission scheme for cooperative NOMA networks with a full-duplex (FD) relay. In this scheme, two pairs of users perform secure transmission with the help of a decode-forward (DF) relay, which forwards information and generates artificial jamming to counteract eavesdropping. The precoding vectors are designed to zero-force the artificial jamming at legal receivers. Then, the channel statistics are calculated, based on which the expressions of secrecy outage probability (SOP) are derived. Simulation results show the accuracy of our analysis, and demonstrate that the proposed scheme can effectively reduce the SOP and improve the effective secrecy throughput via artificial jamming and FD relaying.
Abstract This paper investigates physical layer security analysis of cooperative non-orthogonal multiple access (NOMA) communication system. A virtual full-duplex (VFD) relaying scheme with an untrusted amplify-and-forward (AF) half-duplex (HD) relay and a trusted decode-and-forward (DF) HD relay is used in this system to improve the spectral efficiency. In order to prevent the untrusted relay from eavesdropping, a simple and practical cooperative jamming scheme is designed to confuse the untrusted relay. The exact expressions of effective secrecy throughput (EST) for NOMA users and approximate expression of EST for non-NOMA user are derived. All theoretical results are validated by numerical simulations which demonstrate that the proposed VFD-NOMA scheme is superior to existing HD-NOMA scheme in cooperative system and jamming plays an important role for obtaining acceptable EST. In addition, simulation results shows that the best secrecy performance highly depends on the system parameters such as transmit powers and jamming signal power.
Abstract This paper investigates physical layer security analysis of cooperative non-orthogonal multiple access (NOMA) communication system. A virtual full-duplex (VFD) relaying scheme with an untrusted amplify-and-forward (AF) half-duplex (HD) relay and a trusted decode-and-forward (DF) HD relay is used in this system to improve the spectral efficiency. In order to prevent the untrusted relay from eavesdropping, a simple and practical cooperative jamming scheme is designed to confuse the untrusted relay. The exact expressions of effective secrecy throughput (EST) for NOMA users and approximate expression of EST for non-NOMA user are derived. All theoretical results are validated by numerical simulations which demonstrate that the proposed VFD-NOMA scheme is superior to existing HD-NOMA scheme in cooperative system and jamming plays an important role for obtaining acceptable EST. In addition, simulation results shows that the best secrecy performance highly depends on the system parameters such as transmit powers and jamming signal power.