Backscatter communication system is the backbone of many low cost and low power distributed wireless systems. This paper studies the physical layer security (PLS) performance of a backscatter system which contains several relays and an eavesdropper. We discuss the conditions for a positive secrecy rate of the system in two different situations. First, in the case of known information of eavesdropper, we use a sub-optimal relay selection method to secure backscatter communication and maximize the secrecy rate. The simulation results prove the suboptimal scheme with low complexity achieves the same effects as the optimal one. But the transmission rate is very low due to the difference between the main channel and eavesdropper channel is too little, so we put forward the second distinctive method. Second, without knowing any information of eavesdropper, we adopt the artificial noise (AN) technique to reduce the received signal to interference noise (SINR) of eavesdropper, and came to a conclusion that under the condition of the same system model, adding a weak AN greatly improves the secrecy rate compared to situation one, and it doesn't required to obtain any information of eavesdropper. In small power of this type of communication system, this method is also effective.
Backscatter communication system is the backbone of many low cost and low power distributed wireless systems. This paper studies the physical layer security (PLS) performance of a backscatter system which contains several relays and an eavesdropper. We discuss the conditions for a positive secrecy rate of the system in two different situations. First, in the case of known information of eavesdropper, we use a sub-optimal relay selection method to secure backscatter communication and maximize the secrecy rate. The simulation results prove the suboptimal scheme with low complexity achieves the same effects as the optimal one. But the transmission rate is very low due to the difference between the main channel and eavesdropper channel is too little, so we put forward the second distinctive method. Second, without knowing any information of eavesdropper, we adopt the artificial noise (AN) technique to reduce the received signal to interference noise (SINR) of eavesdropper, and came to a conclusion that under the condition of the same system model, adding a weak AN greatly improves the secrecy rate compared to situation one, and it doesn't required to obtain any information of eavesdropper. In small power of this type of communication system, this method is also effective.
Backscatter wireless communication lies at the heart of many practical low-cost, low-power, distributed passive sensing systems. The inherent cost restrictions coupled with the modest computational and storage capabilities of passive sensors, such as RFID tags, render the adoption of classical security techniques challenging; which motivates the introduction of physical layer security approaches. Despite their promising potential, little has been done to study the prospective benefits of such physical layer techniques in backscatter systems. In this paper, the physical layer security of wireless backscatter systems is studied and analyzed. First, the secrecy rate of a basic single-reader, single-tag model is studied. Then, the unique features of the backscatter channel are exploited to maximize this secrecy rate. In particular, the proposed approach allows a backscatter system's reader to inject a noise-like signal, added to the conventional continuous wave signal, in order to interfere with an eavesdropper's reception of the tag's information signal. The benefits of this approach are studied for a variety of scenarios while assessing the impact of key factors, such as antenna gains and location of the eavesdropper, on the overall secrecy of the backscatter transmission. Numerical results corroborate our analytical insights and show that, if properly deployed, the injection of artificial noise yields significant performance gains in terms of improving the secrecy of backscatter wireless transmission.
The backscatter communication system has tremendous potential in commercial applications, still very less work has been done to study the benefits of it. Backscatter communication system is the backbone of many low cost and low power distributed wireless systems. The data transmission between various nodes in wireless communication system always comes with the risk of third party interception. This leads to privacy and security breaches of the information. In this paper, physical layer security of backscatter wireless system for multiple eavesdropper, single tag, and single reader case is studied. Unique characteristics of the channel are used to provide security to signal transmission. In order to degrade the reception of the signal by eavesdropper, a noise injection scheme is proposed. The advantages of this approach are discussed for various cases while evaluating the impact of the key factors like antenna gain and location of the eavesdropper on the secrecy of the transmission. Analytical results indicate that if properly employed, the noise injection scheme improves the performance of backscatter wireless system.
The prominence of the wireless communication has been urging the monotonically increasing demand of security and privacy. In wireless systems, the notion of perfect secrecy of information with respect to illegitimate nodes can be ensured via physical layer security (PLS) techniques. Unfortunately, they can be made less effective if source- eavesdropper wiretap channel is better than the main source-receiver channel. The various node cooperation schemes can be employed to combat this limitation where a relay node assists the communication to improve the performance significantly. In this paper, a four node wireless communication system consisting of a source, a destination, a relay and an eavesdropper as wire-tapper has been considered. The performance of the traditional cooperation schemes in terms of secrecy rate has been investigated with a different scenario where relay node helps the eavesdropper to deteriorate the secrecy rate. In addition, since legitimate receiver can overhear the transmission of relay, it favours the achievable secrecy rate. We formulate an analytical expression of conditional secrecy outage probability for the investigated system. From the obtained simulation results, it has been observed that secrecy rate is monotonically increases with path loss index. Furthermore, the proper selection of the system parameters leads to enhance the secrecy performance of the system even if relay pertains to degrade the performance. Amplify-and-forward, cooperation, decode-and-Forward, secrecy rate, relay.
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.
The Physical Layer Security (PLS) technology has been proved to be an effective way to reduce information leakage in wireless communication networks. This paper discusses the problem of secure transmission for Amplify-and-Forward (AF) cooperative network which contains both an external eavesdropper and some untrusted relays at the same time, where each relay acts as a helper of transmitting information and a potential eavesdropper. We adopt the technology of Cooperative Jamming (CJ), which yields a significant performance in terms of providing a better level of security against eavesdropping and improving the secure transmission performance of the system. First we discuss the security performance of this new system model, give the secrecy rate in theory and derive a tight lower bound of this secrecy rate. Then we propose a relay selection scheme, which avoids using the channel state information (CSI) of external eavesdropper, to transmit information. Afterward, we also discuss the problem of power allocation in order to maximize the secrecy rate.
Passive eavesdropping compromises confidentiality in wireless networks, especially in resource-constrained environments where heavyweight cryptography is impractical. Physical layer security (PLS) exploits channel randomness and spatial selectivity to confine information to an intended receiver with modest overhead. However, typical PLS techniques, such as using beamforming, artificial noise, and reconfigurable intelligent surfaces, often involve added active power or specialized deployment, and, in many designs, rely on precise time synchronization and perfect CSI estimation, which limits their practicality. To this end, we propose AmbShield, an AmBD-assisted PLS scheme that leverages naturally distributed AmBDs to simultaneously strengthen the legitimate channel and degrade eavesdroppers' without requiring extra transmit power and with minimal deployment overhead. In AmbShield, AmBDs are exploited as friendly jammers that randomly backscatter to create interference at eavesdroppers, and as passive relays that backscatter the desired signal to enhance the capacity of legitimate devices. We further develop a unified analytical framework that analyzes the exact probability density function (PDF) and cumulative distribution function (CDF) of legitimate and eavesdropper signal-to-interference-noise ratio (SINR), and a closed-form secrecy outage probability (SOP). The analysis provides clear design guidelines on various practical system parameters to minimize SOP. Extensive experiments that include Monte Carlo simulations, theoretical derivations, and high-SNR asymptotic analysis demonstrate the security gains of AmbShield across diverse system parameters under imperfect synchronization and CSI estimation.