Untrustworthy Relay Research Articles

Secrecy rate maximization for hardware impaired untrusted relaying network with deep learning

This paper investigates the physical layer security (PLS) design of an untrusted relaying network where the source node coexists with a multi-antenna eavesdropper (Eve). While the communication relies on untrustworthy relay nodes to increase reliability, we aim to protect the confidentiality of information against combined eavesdropping attacks performed by both untrusted relay nodes and Eve. Considering the hardware impairments (HIs), both total power budget constraint for the whole network and the individual power constraint at each node, this paper presents a novel approach to jointly optimize relay beamformer and transmit powers aiming at maximizing average secrecy rate (ASR). To safeguard the first cooperative phase, destination-aided cooperative jamming (DACJ) is employed, while for the second phase, the relay beamformer is adjusted. The resultant optimization problem is non-convex, and a suboptimal solution is obtained through the sequential parametric convex approximation (SPCA) method. In order to prevent any failure due to infeasibility, we propose an iterative initialization algorithm to find the feasible initial point of the original problem instead of an arbitrary point, as in the conventional SPCA. To satisfy low-latency as one of the main key performance indicators (KPI) required in beyond 5G (B5G) communications, a computationally efficient data-driven approach is developed exploiting a deep learning model to evaluate the proposed scheme while the computational burden is significantly reduced. Simulation results assess the effect of different system parameters on the ASR performance as well as the effectiveness of the proposed deep learning solution in large-scale cases.

Effect of Co-channel Interference on Two-Way Untrustworthy Relay Selection

This study investigates the impact of co-channel interference on two-way untrustworthy relay selection over Rayleigh fading environment. The investigation considers that two source terminals make information exchange over J number of full-duplex based amplify-and-forward bi-directional untrustworthy relay in the presence of co-channel interference. In addition, limited number of friendly jammers generate artificial interference/noise signals to mitigate information leakage. So as to minimize the system overhead and also enhancing secrecy performance, the relay selection is made by means of max–min criteria, which is based on maximizing the minimum secrecy rate over the relay terminals. The system model fundamental performance limits are measured by means of secrecy outage probability, secrecy achievable sum rate, intercept probability, and secrecy throughput analysis metrics. According to Monte-Carlo based simulations and numerical results, the max–min based selection strategy achieves cooperative diversity order, which is equal to total number of possible paths, in high signal-to-noise ratio regimes. Results also reveal that the co-channel interference dominates the process of the information exchange and degrades the achievable cooperative diversity order from J to 0 and leads system coding gain losses on free-interference cases in high signal-to-noise ratio regimes.

Impact of co‐channel interference on the leakage rate‐based untrustworthy relay selection

This study investigates the co-channel interference effects on the leakage rate based untrustworthy relay selection strategies. The investigation considers half-duplex, full-duplex, and hybrid leakage rate-based untrustworthy relay selection strategies. The hybrid-based selection strategy dynamically switches between half-duplex and full-duplex modes. The investigation also considers a dual-hop untrustworthy amplify-and-forward based half/full-duplex bi-directional wireless relaying network in the system model. In addition, a finite number of friendly jammers and co-channel interference affect to the untrustworthy relay terminals. According to analytical, asymptotic, and Monte-Carlo simulation results, the co-channel interference slightly degrades the outage probability performance curves and causes system coding gain losses in high signal-to-noise ratio regimes. Results also show that the co-channel interference degrades the system achievable rate performance and causes additional system coding gain losses in high SNR regimes. Results also show that co-channel interference does not have any effect on the system security trade-off performance.

Leakage rate–based untrustworthy relay selection

AbstractThis paper investigates the leakage rate based untrustworthy relay selection strategies, which are based on the untrustworthy relay terminals operate in half‐duplex, full‐duplex, and hybrid modes. The investigation considers a dual‐hop one/two‐way half/full‐duplex wireless relaying network in the system model. The investigation also considers that a finite number of friendly jammers affect the untrustworthy relay terminals. According to analytical, asymptotic, and Monte Carlo simulation results, the LR‐based untrustworthy relay selection strategies achieve cooperative diversity order in high‐signal‐to‐noise ratio. However, friendly jammers and loop interference severely affect the system performance and degrade the achievable diversity order from M to 0 and also cause system coding gain losses. In addition, friendly jammers and loop interference also degrade the system achievable rate performance and cause saturation in high SNRs.

Design and Performance Analysis of Secure Multicasting Cooperative Protocol for Wireless Sensor Network Applications

This letter proposes a new security cooperative protocol, for dual phase amplify-and-forward large wireless sensor networks. In such a network, a portion of the ${K}$ relays can be potential eavesdroppers. The source agrees to share with the destination a given channel state information (CSI) of a source-trusted relay-destination link to encode the message. Then, in the first hop, the source will use this CSI to map the right message to a certain sector while transmitting fake messages to the other sectors using sectoral transmission. In the second hop, the relays retransmit their received signals to the destination, using the distributed beamforming technique. We derived the secrecy outage probability and demonstrated that the probability of receiving the right encoded information by an untrustworthy relay is inversely proportional to the number of sectors. We also showed that the aggressive behavior of the cooperating untrusted relays is not effective compared to the case where each untrusted relay is trying to intercept the transmitted message individually.

Leakage rate‐based untrustworthy relay selection with imperfect channel state information: the outage and security trade‐off analysis

This study investigates the effects of the imperfect channel state information on the leakage rate-based untrustworthy relay selection strategies. The investigation considers that the channel state information is imperfect because of the channel estimation errors and also the feedback delay with time-variant channels. The investigation also considers three different types of leakage rate-based selection strategies, which are half-duplex, full-duplex, and hybrid. The investigation also considers a dual-hop one/two-way amplify-and-forward-based half-/full-duplex wireless relaying network in the system model. In addition, in order to mitigate the information leakage, a finite number of friendly jammers are affecting the untrustworthy relay terminals. According to analytical, asymptotic, and Monte–Carlo simulation results, the leakage rate-based selection strategies achieve cooperative diversity order in high signal-to-noise ratio regimes. The channel estimation error causes system coding gain losses in low signal-to-noise ratio regimes. The feedback delay degrades the achievable diversity order from M to 0 and also causes system coding gain losses in high signal-to-noise ratio regimes. In addition, the friendly jammers and loop-interference also degrade the achievable diversity order and also cause system coding gain losses in high signal-to-noise ratio regimes.

Secure Two-Way Transmission via Wireless-Powered Untrusted Relay and External Jammer

In this paper, we propose a two-way secure communication scheme where two transceivers exchange confidential messages via a wireless powered untrusted amplify-and-forward (AF) relay in the presence of an external jammer. We take into account both friendly jamming (FJ) and Gaussian noise jamming (GNJ) scenarios. Based on the time switching (TS) architecture at the relay, the data transmission is done in three phases. In the first phase, both the energy-starved nodes, the untrustworthy relay and the jammer, are charged by non-information radio frequency (RF) signals from the sources. In the second phase, the two sources send their information signals and concurrently, the jammer transmits artificial noise to confuse the curious relay. Finally, the third phase is dedicated to forward a scaled version of the received signal from the relay to the sources. For the proposed secure transmission schemes, we derive new closed-form lower-bound expressions for the ergodic secrecy sum rate (ESSR) in the high signal-to-noise ratio (SNR) regime. We further analyze the asymptotic ESSR to determine the key parameters; the high SNR slope and the high SNR power offset of the jamming based scenarios. To highlight the performance advantage of the proposed FJ, we also examine the scenario of without jamming (WoJ). Finally, numerical examples and discussions are provided to acquire some engineering insights, and to demonstrate the impacts of different system parameters on the secrecy performance of the considered communication scenarios. The numerical results illustrate that the proposed FJ significantly outperforms the traditional one-way communication and the Constellation rotation approach, as well as our proposed benchmarks, the two-way WoJ and GNJ scenarios.

Perfect Secrecy in Physical-Layer Network Coding Systems From Structured Interference

Physical-layer network coding (PNC) has been proposed for next generation networks. In this paper, we investigate PNC schemes with embedded perfect secrecy by exploiting structured interference in relay networks with two users and a single relay. In a practical scenario where both users employ finite and uniform signal input distributions, we establish upper bounds (UBs) on the achievable perfect secrecy rates and make these explicit when pulse amplitude modulation modems are used. We then describe two simple, explicit encoders that can achieve perfect secrecy rates close to these UBs with respect to an untrustworthy relay in the single antenna and single relay setting. Last, we generalize our system to a multiple-input multiple-output relay channel, where the relay has more antennas than the users and study optimal precoding matrices, which maintain a required secrecy constraint. Our results establish that the design of PNC transmission schemes with enhanced throughput and guaranteed data confidentiality is feasible in next generation systems.

Performance Study of Two-Hop Amplify-and-Forward Systems With Untrustworthy Relay Nodes

This paper investigates the problem of secure communication for amplify-and-forward (AF) systems with untrustworthy relay nodes. To achieve positive secrecy rate, the destination-based jamming (DBJ) technique is applied. We first focus on the single-relay scenario, for which the closed-form expression for the lower bound of the ergodic secrecy capacity (ESC) is derived. Afterward, we extend the DBJ method to the multi-relay scenario and propose a secure relay selection scheme that can maximize the achievable secrecy rate. Based on the extreme-value theory, the approximate ESC is characterized. Our work reveals an interesting result that, when the relay nodes are untrustworthy, the system performance worsens as the number of relays increases.

Distributed Cooperative Transmission with Unreliable and Untrustworthy Relay Channels

Cooperative transmission is an emerging wireless communication technique that improves wireless channel capacity through multiuser cooperation in the physical layer. It is expected to have a profound impact on network performance and design. However, cooperative transmission can be vulnerable to selfish behaviors and malicious attacks, especially in its current design. In this paper, we investigate two fundamental questions Does cooperative transmission provide new opportunities to malicious parties to undermine the network performance? Are there new ways to defend wireless networks through physical layer cooperation? Particularly, we study the security vulnerabilities of the traditional cooperative transmission schemes and show the performance degradation resulting from the misbehaviors of relay nodes. Then, we design a trust-assisted cooperative scheme that can detect attacks and has self-healing capability. The proposed scheme performs much better than the traditional schemes when there are malicious/selfish nodes or severe channel estimation errors. Finally, we investigate the advantage of cooperative transmission in terms of defending against jamming attacks. A reduction in link outage probability is achieved.