In this paper, we investigate the physical-layer security for a wireless two-hop relay network in the presence of channel estimation errors when estimating the channel state information (CSI) of the main links (from the source via relays to the destination) and wiretap links (from the source and relays to the eavesdropper). The eavesdropper can not only overhear the confidential signals transmitted by the relays, but also tap the secret messages transmitted by the source. We present an channel estimation error oriented relay selection (CEEoRS) scheme to improve the security-reliability tradeoff (SRT). We also analyze the intercept probability and outage probability of the CEEoRS scheme, where the intercept probability and outage probability can quantify the security and reliability, respectively. For comparison purposes, the traditional direct transmission with channel estimation errors (TDTwCEE) is also analyzed. It is shown that the proposed CEEoRS scheme outperforms the TDTwCEE scheme in terms of its SRT. More specifically, the proposed CEEoRS scheme is capable of significantly improving the SRT performance of wireless communications through increasing the number of relays.
In this paper, we investigate the physical-layer security for a wireless two-hop relay network in the presence of channel estimation errors when estimating the channel state information (CSI) of the main links (from the source via relays to the destination) and wiretap links (from the source and relays to the eavesdropper). The eavesdropper can not only overhear the confidential signals transmitted by the relays, but also tap the secret messages transmitted by the source. We present an channel estimation error oriented relay selection (CEEoRS) scheme to improve the security-reliability tradeoff (SRT). We also analyze the intercept probability and outage probability of the CEEoRS scheme, where the intercept probability and outage probability can quantify the security and reliability, respectively. For comparison purposes, the traditional direct transmission with channel estimation errors (TDTwCEE) is also analyzed. It is shown that the proposed CEEoRS scheme outperforms the TDTwCEE scheme in terms of its SRT. More specifically, the proposed CEEoRS scheme is capable of significantly improving the SRT performance of wireless communications through increasing the number of relays.
This paper investigates the physical-layer security (PLS) of wireless transmissions with the aid of multiple decode-and-forward one-way relays in the presence of both eavesdropping attacks and channel estimation errors (CEEs). To protect wireless transmission with CEE, two opportunistic relaying schemes are conceived to upgrade the PLS of the wireless communications with the aid of relays, namely, the CEE-oriented pure relay selection (CEE-PRS) and CEE-oriented jammer-aided relay selection (CEE-JRS), respectively. Moreover, the security-reliability tradeoff (SRT) is designed due to that increasing the transmit power may enhance the reliability, but the security may be sacrificed concurrently, where the security and reliability are characterized by the intercept probability (IP) and outage probability (OP), respectively. We then analyze the IP and OP of the CEE-PRS and CEE-JRS schemes. Furthermore, both the CEE-oriented direct transmission (CEE-DT) and the perfect channel estimation-oriented direct transmission (PCE-DT) schemes are also analyzed for comparison purposes. It is shown that although the SRT of the wireless communications can indeed be degraded by the eavesdropping attacks in low CEE regions, the proposed CEE-PRS and CEE-JRS schemes are capable of significant improving the SRT performance of wireless communications, demonstrating the advantage of the proposed CEE-PRS and CEE-JRS schemes against eavesdropping.
This article examines secrecy coding aided wireless communications from a source to a destination in the presence of an eavesdropper from an SRT perspective. Explicitly, security is quantified in terms of the intercept probability experienced at the eavesdropper, while the outage probability encountered at the destination is used to measure transmission reliability. We characterize the SRT of conventional direct transmission from the source to the destination and show that if the outage probability is increased, the intercept probability decreases, and vice versa. We first demonstrate that the employment of relay nodes for assisting source-destination transmission is capable of defending against eavesdropping, followed by quantifying the benefits of SRS as well as MRS schemes. More specifically, in the SRS scheme, only the single "best" relay is selected for forwarding the source signal to the destination, whereas the MRS scheme allows multiple relays to participate in this process. It is illustrated that both the SRS and MRS schemes achieve a better SRT than conventional direct transmission, especially upon increasing the number of relays. Numerical results also show that, as expected, MRS outperforms SRS in terms of its SRT. Additionally, we present some open challenges and future directions for wireless relay aided physical-layer security.
In this paper, we explore the physical layer security of an Internet of Things (IoT) network comprised of multiple relay-user pairs in the presence of multiple malicious eavesdroppers and channel estimation error (CEE). In order to guarantee secure transmission with channel estimation error, we propose a channel estimation error oriented joint relay-user pair and friendly jammer selection (CEE-JRUPaFJS) scheme to improve the physical layer security of IoT networks. For the purpose of comparison, the channel estimation error oriented traditional round-robin (CEE-TRR) scheme and the channel estimation error oriented traditional pure relay-user pair selection (CEE-TPRUPS) scheme are considered as benchmark schemes. The exact closed-form expressions of outage probability (OP) and intercept probability (IP) for the CEE-TRR and CEE-TPRUPS schemes as well as the CEE-JRUPaFJS scheme are derived over Rayleigh fading channels, which are employed to characterize network reliability and security, respectively. Moreover, the security-reliability tradeoff (SRT) is analyzed as a metric to evaluate the tradeoff performance of CEE-JRUPaFJS scheme. It is verified that the proposed CEE-JRUPaFJS scheme is superior to both the CEE-TRR and CEE-TPRUPS schemes in terms of SRT, which demonstrates our proposed CEE-JRUPaFJS scheme are capable of improving the security and reliability performance of IoT networks in the face of multiple eavesdroppers. Moreover, as the number of relay-user pairs increases, CEE-TPRUPS and CEE-JRUPaFJS schemes offer significant increases in SRT. Conversely, with an increasing number of eavesdroppers, the SRT of all these three schemes become worse.
In this paper, we investigate the physical-layer security of cooperative communications relying on multiple two-way relays using the decode-and-forward (DF) protocol in the presence of an eavesdropper, where the eavesdropper appears to tap the transmissions of both the source and of the relay. The design tradeoff to be resolved is that the throughput is improved by invoking two-way relaying, but the secrecy of wireless transmissions may be degraded, since the eavesdropper may overhear the signals transmitted by both the source and relay nodes. We conceive an artificial noise aided two-way opportunistic relay selection (ANaTWORS) scheme for enhancing the security of the pair of source nodes communicating with the assistance of multiple two-way relays. Furthermore, we analyze both the outage probability and intercept probability of the proposed ANaTWORS scheme, where the security and reliability are characterized in terms of the intercept probability and the security outage probability. For comparison, we also provide the security-reliability tradeoff (SRT) analysis of both the traditional direct transmission and of the one-way relaying schemes. It is shown that the proposed ANaTWORS scheme outperforms both the conventional direct transmission, as well as the one-way relay methods in terms of its SRT. More specifically, in the low main-user-to-eavesdropper ratio (MUER) region, the proposed ANaTWORS scheme is capable of guaranteeing secure transmissions, whereas no SRT gain is achieved by conventional one-way relaying. In fact, the one-way relaying scheme may even be inferior to the traditional direct transmission scheme in terms of its SRT.
In this paper, we consider a dual-hop decode-and-forward (DF) relay network which consists of a source, a destination and multiple DF relays in the presence of an eavesdropper, where the source transmits its data to the destination with the help of DF relays while the eavesdropper attempts to tap the relay transmissions. We examine the impact of channel estimation errors on the secrecy performance of source-destination transmissions and propose an optimal relay selection scheme for improving the transmission security against eavesdropping. To be specific, the proposed relay selection is designed by considering the fact that the channel state information (CSI) of any link from the source via DF relays to destination is inaccurate with channel estimation errors. The traditional round-robin relay selection is also considered for comparison purposes. We derive close-form expressions of the secrecy outage probability for both the proposed optimal relay selection scheme and traditional round-robin relay selection schemes. Numerical results demonstrate an adverse effect of the channel estimation errors on the secrecy outage probability of cooperative relay systems. Additionally, it is shown that the proposed optimal relay selection scheme substantially outperforms the traditional round-robin selection approach in terms of the secrecy outage probability.
In this work, a two-phase optimal-relay transmission scheme for relay networks against eavesdropper is proposed. The security and the reliability performance of this scheme are evaluated in the form of the intercept probability and the outage probability, respectively. In addition, the closed-form expression of security-reliability tradeoff (SRT) is obtained to show the compromise of the security and reliability performance of the system. Specifically, instead of common assumptions of perfect global channel state information in most literature, the channel estimation error and its effects on performance analysis are considered in this paper. It is shown that the security (or reliability) can be enhanced by degrading the reliability (or security) requirement, and the performance can be improved by increasing the number of relays. Finally, simulation results are provided to corroborate our proposed studies.