This paper tackles the challenge of secure and reliable data transmission in diamond network configurations featuring two untrusted relays with low-security clearance. We propose an innovative approach that employs lossy-decode and -forward relaying at these untrusted relays to boost transmission reliability while safeguarding the source information from potential eavesdroppers. An essential contribution of this work is the introduction of the reliable and secure probability (RSP) metric. This metric assesses the likelihood of the destination successfully retrieving the original information while maintaining its confidentiality from untrusted relays. Our analysis shows that the integration of cooperative jamming signals markedly enhances the RSP, resulting in superior security and reliability. Simulation results confirm that optimal power distribution among the source, relays, and destination further maximizes the RSP. These findings underscore the effectiveness of our proposed scheme in ensuring secure and reliable communication in environments with untrusted relays, suggesting its potential as a robust solution for secure communications in diamond network configurations.
This paper tackles the challenge of secure and reliable data transmission in diamond network configurations featuring two untrusted relays with low-security clearance. We propose an innovative approach that employs lossy-decode and -forward relaying at these untrusted relays to boost transmission reliability while safeguarding the source information from potential eavesdroppers. An essential contribution of this work is the introduction of the reliable and secure probability (RSP) metric. This metric assesses the likelihood of the destination successfully retrieving the original information while maintaining its confidentiality from untrusted relays. Our analysis shows that the integration of cooperative jamming signals markedly enhances the RSP, resulting in superior security and reliability. Simulation results confirm that optimal power distribution among the source, relays, and destination further maximizes the RSP. These findings underscore the effectiveness of our proposed scheme in ensuring secure and reliable communication in environments with untrusted relays, suggesting its potential as a robust solution for secure communications in diamond network configurations.
This letter considers a diamond network with two untrusted relays with low-security clearance level. Lossy decoder-and-forward is utilized at both the untrusted relays to enhance the reliability of transmission and to keep the source information confidential to the untrusted relays. The reliable-and-secure probability (RSP), which is the probability that the original messages can be retrieved at the destination while keeping confidential to the relays, is derived. It is found that with the help of cooperative jamming signal, superior reliability and security performance in terms of RSP can be achieved.
This paper investigates short-packet communications over a diamond relay network with two untrusted relays (potential eavesdroppers) with the purpose of guaranteeing reliability and security simultaneously. As the performance metric, reliable-and-secure probability (RSP), considering both reliability and secrecy, is defined from the perspective of physical layer security. An analytical approach is proposed to investigate reliability and security by taking into account the characteristics of the short-packet transmission. RSPs are numerically obtained via the analytical framework by utilizing the source-channel separation theorem for the source-to-relay transmission and chief executive officer (CEO) problem analyses for the relay-to-destination transmission. It is found that the optimal RSP is achieved when the contributions from the source-relay transmission and the relay-destination transmission are balanced, even without support from a friendly jamming signal or artificial noise.
In this paper, we investigate the physical layer security performance of untrusted decode-and-forward (DF) relay networks allowing intra-link errors with cooperative jamming. Different from traditional DF relaying protocol, the decoded message at the relay will always be forwarded to the destination node in decode-and-forward relaying allowing intra-link errors (DF-IE), which can be leveraged to enhance the security of relay networks with untrusted relays. To further improve the security performance of DF-IE, we allow the destination node to send jamming signals to impair the signal reception at the relay node, which is referred to as DF-IE with cooperative jamming (DF-IE-CJ). Reliable-and-secure probability (RSP) is used to evaluate the performance of the untrusted relay networks, which represents the probability that the destination node can successfully decode the original message sent from the source node while the relay node can not decode the original message. First, the RSP of DF-IE-CJ is derived from a fading scenario where all the channels between the nodes suffer from block Rayleigh fading. Next, we propose a power allocation scheme to maximize the RSP with different signal-to-noise ratios (SNRs). To verify the effectiveness of DF-IE-CJ, we compare the RSP performance of DF-IE-CJ with that of a widely used schemes, cooperative jamming (CJ). A series of numerical simulations verified the accuracy of the theoretical analysis, and the superiority of DF-IE-CJ over CJ about 5% in RSP.
In this paper, we examine the physical layer security (PLS) in lossy untrusted relay networks, focusing on finite blocklength transmissions. In such networks, ensuring secure communication is particularly challenging due to the presence of untrusted relay nodes and the inherent limitations of short-packet transmissions. We propose the reliable-and-secure probability (RSP) as a performance metric to evaluate the likelihood that the destination node successfully recovers the transmitted message while untrusted relays experience an outage. Two basic network topologies are taken into consideration, which are the three-node one way network and the single-source multi-untrusted-relay network without direct source-to-destination link. By optimizing power allocation and relay positioning, the RSP can be significantly improved, even when decoding errors occur at the relays. The study demonstrates that lossy decode-and-forward relaying complicates secure communication but also presents opportunities for performance enhancement through careful resource management. Numerical simulations validate the effectiveness of the proposed optimization strategies in enhancing security, especially for applications in ultra-reliable low-latency communication and massive machine-type communication in 5G/6G networks. Future research will focus on deriving more precise closed-form expressions for RSP in finite blocklength settings and investigating machine learning-based approaches for real-time optimization of secure communications in dynamic wireless environments. This study contributes to the growing body of knowledge on PLS in modern wireless systems, offering insights for future advancements.
A two-untrusted-relay transmission scheme is proposed with lossy-forward (LF) relaying being utilized. Two untrusted relays are located between one source and one common destination and there is no direct link between the source and the destination, which referred to as diamond relaying network. Since LF relaying allows intra-link errors and always forwards the decoded information sequences from the relays to the destination, it realizes the reliable and secure transmission of decoder-and-forward based relay networks with untrusted relays. Reliable-and-secure probability is derived to evaluate the performance of the untrusted relay networks, which represents the probability that the destination can recover the original message sent from the source whereas the relays cannot. We find that as long as the contributions of the transmit power of source and relays are balanced, a certain degree of reliable-and-secure probability can be held, even without the support from a friendly jamming signal.
In this work, by considering a variety of realistic hardware impairments, we aim to enhance the security of a cooperative relaying network, where a source intends to transmit its confidential information to a destination in the presence of a group of untrusted amplify-and-forward relays, as potential eavesdroppers (Eves), and an entirely passive multiple-antenna aided Eve. Our goal is to safeguard the information against these two types of eavesdropping attacks, while simultaneously relying on the untrusted relays to boost both the security and reliability of the network. To reach this goal, we propose a novel joint cooperative beamforming, jamming and power allocation policy to safeguard the confidential information while concurrently achieving the required quality-of-service at the destination. We also take into account both the total power budget constraint and a practical individual power constraint for each node. Our optimization problem can be split into two consecutive sub-problems. In the first sub-problem, we are faced with a non-convex problem which can be transformed into the powerful difference of convex (DC) program. A low-complexity iterative algorithm is proposed to solve the DC program, which relies on the constrained concave-convex procedure (CCCP). We further introduce a novel initialization method, which is based on a feasible point of the original problem obtained from a novel iterative feasibility search procedure, rather than an arbitrary (infeasible) point as in the conventional CCCP. The second sub-problem of our optimization problem is a convex optimization problem and can be solved efficiently adopting the classic interior point method. The numerical results provided illustrate that although the trusted relaying scenario outperforms the untrusted relaying for small and medium total power budgets, however, by increasing the total power budget, the secrecy performances of both the trusted and untrusted relaying converge to the same. Additionally, by equally sharing the total impairments at the relays between the transmitter and the receiver the best secrecy performance is presented.