Wireless Physical Layer Security Research Articles

Optimal Age of Information and Throughput Scheduling in Heterogeneous Traffic Wireless Physical-Layer Security Communications

Optimal Age of Information and Throughput Scheduling in Heterogeneous Traffic Wireless Physical-Layer Security Communications

A coding scheme to force the eavesdropper falling in error avalanche

AbstractIn recent years, key generation schemes based on the reciprocity of wireless channels have gained widespread attention in the field of wireless physical layer security. However, due to the openness of wireless channels, eavesdroppers may obtain partial legitimate keys by eavesdropping on the wireless channel. To address this issue, this paper proposes a wireless channel coding scheme that induces an “avalanche” of errors for eavesdroppers, which could maximize eavesdropper's bit error rate. The design of this scheme is based on the significant differences between the eavesdropping channel and the legitimate channel, and the average bit key disagreement ratio of the keys generated by the legitimate channel is around 8%. The scheme selects polar codes with strong error correction capabilities and chooses a coding rate matching the error level of the legitimate channel, forcing the eavesdropping channel's error rate into an “avalanche” state, where the error rate approaches 50%. This paper presents the structure of the encoder and determines the coding rate through simulation. Simulation results demonstrate that this scheme can significantly degrade the error rate of the eavesdropping channel while ensuring the prevention of eavesdroppers from obtaining secret information transmitted through the legitimate channel.

A Reconfigurable Phase-Time Array Transmitter Achieving Keyless Secured Transmission and Multi-Receiver Localization for Low-Latency Joint Communication and Sensing

The vast available spectrum at millimeter-wave (mm-Wave)/terahertz (THz) frequencies is envisioned as a key enabler to solve the ever-increasing data rate needs in crowded urban environments and lead the next wireless technology revolution. To overcome the high path loss present at mm-Wave/THz, highly directional antenna arrays have become ubiquitous. Their future large-scale deployment will naturally create dense wireless sensor networks, which in-turn enable joint communication and sensing. However, the beamforming of high-directivity antenna arrays relies on real-time precise localization between transmitters (TXs) and receivers (RXs) to ensure robustness in dynamic mobile applications. Moreover, traditional digital encryption and decryption at multi-Gbps data rate cause large power and latency overhead, and thus, wireless physical layer security has become a promising solution. In this article, we propose and demonstrate a reconfigurable phase-time array (PTA) TX with prism-like spectral-to-spatial mapping of wideband transmitted signals, which achieves keyless physically secured wireless communication and fast multi-RX localization to enable low-latency joint communication and sensing within the same wireless electronics frontend. The PTA realizes reconfigurable spectral-to-spatial mapping by applying both a phase shift and true time delay (TTD) at each array element. This intentionally creates and exploits the array beam squinting effect, such that different frequency components of a wideband signal are transmitted in different directions, analogous to an optical prism. Therefore, multiple RX nodes can simultaneously determine their angular positions relative to the TX array using their received signals for fast multi-RX localization. Judiciously engineering the prism-like beam squinting in PTA TX can also selectively distort signal transmission to unwanted directions for secured communication without cryptography. Furthermore, the PTA scheme can reconfigure its element-level phase-time delay combinations to attain variable levels of communication security and localization/sensing performance depending on the needs.

Performance of multi-antenna wireless systems based on time reversal

5G wireless mobile communication system is faced with massive equipment access, information security and effective transmission is worth paying attention to. Wireless physical layer security mainly uses encryption principle to enhance the security of information transmission, while time reversal technology combines its electromagnetic characteristics and physical channel characteristics to improve the security performance of wireless communication system. In this paper, a signal transmission model of wireless multi-antenna communication system based on time reversal cavity is proposed and white Gaussian noise is introduced. The simulation results show that the space-time focusing characteristics of time reversal cavity can make the signal energy more concentrated on the target user, which can not only effectively alleviate the communication quality problems caused by multipath effect, but also ensure the security of information transmission process.

Joint Active and Passive Beamforming Design for the IRS-Assisted MIMOME-OFDM Secure Communications

The effective combination of physical layer security communication and intelligent reflecting surface (IRS) technology has recently attracted extensive attention to improve the system security. Unlike existing works that mostly focus on single-carrier systems, we consider an IRS-assisted multi-carrier MIMO wireless physical layer security communication system, which consists of a legitimate transmitter, a legitimate receiver, an IRS node and an eavesdropper. With the aim of maximizing the sum secrecy rate, the multi-carrier transmit beamforming and IRS reflecting coefficient matrix are jointly optimized under the constraints on the transmit power budget and unit modulus of IRS reflecting coefficients. Since the formulated problem is non-convex, an alternate optimization (AO) algorithm is proposed to deal with it. Specifically, for the given IRS reflecting coefficient matrix, the minorization-maximization (MM) scheme is adopted to approximate the objective function of the subproblem and following that, the closed-form solution of the multi-carrier transmit beamforming is obtained through the Lagrange multiplier method. Then, for the given multi-carrier beamforming, the IRS reflecting coefficient matrix is also optimized through the MM scheme and a suboptimal closed-form solution that satisfies the KKT conditions is derived. Moreover, the discussion is extended to the discrete IRS phase shift case and a heuristic projection method (HPM) is then proposed. Finally, the simulation results validate the effectiveness of the proposed AO based algorithm.

On The Secrecy Performance Over N-Wave With Diffuse Power Fading Channel

We investigate the realistic propagation conditions effects on wireless physical layer security, which are different from classical Rice and Rayleigh fading. Specifically, we study how the superposition of a number of dominant specular waves and diffusely propagating components impacts the achievable secrecy performance. We derive analytical expressions for the secrecy outage probability and the average secrecy capacity, which have similar complexity to other alternatives in the literature derived for simpler fading models. We provide very useful insights on the impact on physical layer security of $(i)$ the number; $(ii)$ the relative amplitudes and $(iii)$ the overall power of the dominant specular components. We show that it is possible to obtain remarkable improvements on the system secrecy performance when: $(a)$ the relative amplitudes of the dominant specular components for the legitimate channel are more unbalanced compared to those of the eavesdropper's channel, and $(b)$ the power of the dominant components for the main channel is significantly larger than the power of the dominant components for the wiretap channel.

On the Beneficial Role of a Finite Number of Scatterers for Wireless Physical Layer Security

We show that for a legitimate communication under multipath quasi-static fading with a reduced number of scatterers, it is possible to achieve perfect secrecy even in the presence of a passive eavesdropper for which no channel state information (CSI) is available. Specifically, we show that the outage probability of secrecy capacity (OPSC) is zero for a given range of average signal-to-noise ratios (SNRs) at the legitimate and eavesdropper's receivers. As an application example, we analyze the OPSC for the case of two scatterers, explicitly deriving the relationship between the average SNRs, the secrecy rate R S and the fading model parameters required for achieving perfect secrecy. The impact of increasing the number of scatterers is also analyzed, showing that it is always possible to achieve perfect secrecy in this scenario, provided that (i) the dominant specular component for the legitimate channel is sufficiently large compared to the remaining scattered waves, and (ii) a exclusion area on which no eavesdroppers can be placed is considered.

Exploiting Array Pattern Synthesis for Physical Layer Security in Millimeter Wave Channels

In this paper, we propose a beamformer design scheme for wireless physical layer security using partial channel state information (CSI) in millimeter wave channels. The partial CSI used in this work is the range of angle-of-departure (AOD). Assuming that the AOD range of each node is available, we design a transmit beamformer using semidefinite programming based on array pattern synthesis. Numerical results are presented to verify the secrecy rates achieved by the proposed scheme.

Securing UAV Communications via Joint Trajectory and Power Control

Unmanned aerial vehicle (UAV) communication is anticipated to be widely applied in the forthcoming fifth-generation wireless networks, due to its many advantages such as low cost, high mobility, and on-demand deployment. However, the broadcast and line-of-sight nature of air-to-ground wireless channels give rise to a new challenge on how to realize secure UAV communications with the destined nodes on the ground. This paper aims to tackle this challenge by applying the physical layer security technique. We consider both the downlink and uplink UAV communications with a ground node, namely, UAV-to-ground (U2G) and ground-to-UAV (G2U) communications, respectively, subject to a potential eavesdropper on the ground. In contrast to the existing literature on the wireless physical layer security only with the ground nodes at fixed or quasi-static locations, we exploit the high mobility of the UAV to proactively establish favorable and degraded channels for the legitimate and eavesdropping links, through its trajectory design. We formulate new problems to maximize the average secrecy rates of the U2G and G2U transmissions, by jointly optimizing the UAV’s trajectory, and the transmit power of the legitimate transmitter over a given flight period of the UAV. Although the formulated problems are non-convex, we propose iterative algorithms to solve them efficiently by applying the block coordinate descent and successive convex optimization methods. Specifically, both the transmit power and UAV trajectory are optimized, with the other being fixed in an alternating manner, until the algorithms converge. The simulation results show that the proposed algorithms can improve the secrecy rates for both U2G and G2U communications, as compared to other benchmark schemes without power control and/or trajectory optimization.

A Survey of Optimization Approaches for Wireless Physical Layer Security

Due to the malicious attacks in wireless networks, physical layer security has attracted increasing concerns from both academia and industry. The research on physical layer security mainly focuses either on the secrecy capacity/achievable secrecy rate/capacity-equivocation region from the perspective of information theory, or on the security designs from the viewpoints of optimization and signal processing. Because of its importance in security designs, the latter research direction is surveyed in a comprehensive way in this paper. The survey begins with typical wiretap channel models to cover common scenarios and systems. The topics on physical-layer security designs are then summarized from resource allocation, beamforming/precoding, and antenna/node selection and cooperation. Based on the aforementioned schemes, the performance metrics and fundamental optimization problems are discussed, which are generally adopted in security designs. Thereafter, the state of the art of optimization approaches on each research topic of physical layer security is reviewed from four categories of optimization problems, such as secrecy rate maximization, secrecy outrage probability minimization, power consumption minimization, and secure energy efficiency maximization. Furthermore, the impacts of channel state information on optimization and design are discussed. Finally, the survey concludes with the observations on potential future directions and open challenges.

Impact of Mobility on Physical Layer Security Over Wireless Fading Channels

Wireless physical layer security has attracted great attention in recent years. Although mobility is an intrinsic property of wireless networks, most of the existing works only consider static scenarios and the impact of mobility on wireless physical layer security is not well understood. To fill this gap, in this paper, we investigate physical layer security in the scenario with a random mobile receiver under Rayleigh fading channel. We consider a common scenario where a base station or access point communicates to a random mobile receiver with a passive eavesdropper in a circular region. The secrecy performances under three typical random mobility models are studied: random waypoint model (RWP); random direction model (RD); and border move model. We investigate the secrecy characteristics of the mobile user under steady-state running and provide a general analytical framework for computing the ergodic secrecy capacity. We derive tractable closed-form expressions of positive secrecy capacity probability and secrecy outage probability for RWP and RD mobility users, respectively. By comparing the secrecy performance of mobility with static case, we find that the RWP mobile user can achieve much better secrecy performance than the others. We then investigate the secrecy performance of RWP mobile user with pause time. Furthermore, the two types of secrecy improvement strategies for random mobile users are proposed. In the first strategy, a transmit subcell for RWP users is bounded. We allow the transmitter to communicate with the mobile user only when he is moving within the subcell. In the other strategy, the transmitter is turned on only when the evaluated secrecy performance reaches to a required level. We strike a good trade-off between the secrecy improvements and transmit outage probability. Extensive simulation results validate our theoretical analysis. Finally, we extend our framework to other realistic scenarios, including nodes moving in other shapes of areas, and multiple non-cooperative and cooperative eavesdroppers.

A Joint Optimization Scheme for Artificial Noise and Transmit Filter for Half and Full Duplex Wireless Cyber Physical Systems

While half and full duplex wireless enabled cyber physical systems (CPSs) are gaining more importance and research attention, maintaining the security of CPS systems remains a vital challenge. The broadcast nature of wireless channels makes it possible for unauthorized receivers, called eavesdroppers, to capture the information signal. Wireless physical layer security techniques aim to harden the secrecy characteristics of wireless systems, decreasing the signal quality of a prospective eavesdropper. This paper considers a joint optimization of artificial noise (AN) signal and transmit filter for the information signals in order to achieve a target secrecy level. As eavesdropping attacks are very critical threats in CPS networks, and the need for high secrecy techniques remains valid. The proposed framework includes a scenario with two multi-antenna legitimate parties and a multi-antenna eavesdropper node (or multiple cooperating eavesdroppers). The transmit filter and AN signal are jointly optimized by the transmitters, where receiver nodes can make use of optimal transmit filters. The problem is derived for the cases where the legitimate CPS nodes perform full duplex and half duplex transmissions. The impact of channel estimation errors and self interference are also discussed.

Proactive Eavesdropping via Pilot Contamination and Jamming

Proactive eavesdropping is a new paradigm shift in wireless physical layer security from preventing conventional eavesdropping attacks to legitimate intercepting suspicious communications, which has attracted a lot of attention recently. Pilot contamination is one effective technique in proactive eavesdropping, which spoofs the suspicious transmitter on channel estimation by sending the same pilot signal as the suspicious receiver, and lets it leak information in the direction of the legitimate eavesdropper during its transmission. However, this technique may fail when an anti-pilot-contamination mechanism called “energy ratio detector (ERD)” is applied at the suspicious receiver. To deal with the case that the suspicious receiver is a smart device using ERD, in this paper, we study using pilot contamination along with jamming to improve the legitimate eavesdropping performance. We first derive a closed-form expression for the probability of pilot contamination being detected by the suspicious receiver, and use it to obtain a closed-form expression for the eavesdropping rate. Using this theoretical analysis result, we propose an algorithm to maximize the eavesdropping rate by jointly optimizing the pilot contamination power and jamming power via two-dimensional search. Simulation results show that the proposed eavesdropping rate maximization algorithm can significantly improve eavesdropping rate, as compared to other benchmark schemes.

Improving Wireless Physical Layer Security Using Constant Envelope Chirped OFDM

The broadcasting nature of wireless communication creates challenges in attaining secure communication. Different approaches have been implemented to increase security in wireless communication with physical layer security being affordable choices as it attains secure communication with the same throughput and easily integrated with higher level security measures. Different physical characteristics of wireless channels can be exploited to implement physical layer security and in our research channel attenuation between transmitter and receiver were used. To provide cost effective and secure wireless communication we used constant envelope chirped OFDM (CE-chirped OFDM) with its subcarriers dynamically arranged based on the wireless channel response between the transmitter and a legal receiver. The security is further increasing by assigning identification number for each transmitter–receiver pair and the identifications numbers are boost arrangement of the subcarriers and increase system security. Different simulations were conducted and the simulations shows increase of system security when wireless channel attenuation of CE chirped OFDM is used to secure the communication between transmitter and legal receiver with the same symbol error rate as convectional OFDM and chirped OFDM.

Wireless physical layer security

Security in wireless networks has traditionally been considered to be an issue to be addressed separately from the physical radio transmission aspects of wireless systems. However, with the emergence of new networking architectures that are not amenable to traditional methods of secure communication such as data encryption, there has been an increase in interest in the potential of the physical properties of the radio channel itself to provide communications security. Information theory provides a natural framework for the study of this issue, and there has been considerable recent research devoted to using this framework to develop a greater understanding of the fundamental ability of the so-called physical layer to provide security in wireless networks. Moreover, this approach is also suggestive in many cases of coding techniques that can approach fundamental limits in practice and of techniques for other security tasks such as authentication. This paper provides an overview of these developments.

Physical Layer Security Using Two-Path Successive Relaying.

Relaying is one of the useful techniques to enhance wireless physical-layer security. Existing literature shows that employing full-duplex relay instead of conventional half-duplex relay improves secrecy capacity and secrecy outage probability, but this is at the price of sophisticated implementation. As an alternative, two-path successive relaying has been proposed to emulate operation of full-duplex relay by scheduling a pair of half-duplex relays to assist the source transmission alternately. However, the performance of two-path successive relaying in secrecy communication remains unexplored. This paper proposes a secrecy two-path successive relaying protocol for a scenario with one source, one destination and two half-duplex relays. The relays operate alternately in a time division mode to forward messages continuously from source to destination in the presence of an eavesdropper. Analytical results reveal that the use of two half-duplex relays in the proposed scheme contributes towards a quadratically lower probability of interception compared to full-duplex relaying. Numerical simulations show that the proposed protocol achieves the ergodic achievable secrecy rate of full-duplex relaying while delivering the lowest probability of interception and secrecy outage probability compared to the existing half duplex relaying, full duplex relaying and full duplex jamming schemes.

Improving Wireless Physical Layer Security via Exploiting Co-Channel Interference

This paper considers a scenario in which a source-destination pair needs to establish a confidential connection against an external eavesdropper, aided by the interference generated by another source-destination pair that exchanges public messages. The goal is to compute the maximum achievable secrecy degrees of freedom (S.D.o.F) region of a MIMO two-user wiretap network. First, a cooperative secrecy transmission scheme is proposed, whose feasible set is shown to achieve all S.D.o.F. pairs on the S.D.o.F. region boundary. In this way, the determination of the S.D.o.F. region is reduced to a problem of maximizing the S.D.o.F. pair over the proposed transmission scheme. The maximum achievable S.D.o.F. region boundary points are obtained in closed form, and the construction of the precoding matrices achieving the maximum S.D.o.F. region boundary is provided. The obtained analytical expressions clearly show the relation between the maximum achievable S.D.o.F. region and the number of antennas at each terminal.

Cooperative Relaying Protocol for Improving Physical Layer Security in Wireless Decode-and-Forward Relaying Networks

In this paper, we consider cooperative relaying protocols for enhancing wireless physical layer security. For time-division multiple-access based cooperative protocols, we analyze achievable secrec...

Multi-antenna relay aided wireless physical layer security

With the growing popularity of mobile Internet, providing secure wireless services has become a critical issue. Physical layer security (PHY-security) has been recognized as an effective means to enhance wireless security by exploiting wireless medium characteristics, for example, fading, noise, and interference. A particularly interesting PHY-security technology is cooperative relay due to the fact that it helps to provide distributed diversity and shorten access distance. This article offers a tutorial on various multi-antenna relaying technologies to improve security at physical layer. The state-of-the-art research results on multi-antenna relay aided PHY-security as well as some secrecy performance optimization schemes are presented. In particular, we focus on large-scale MIMO relaying technology, which is effective in tackling various challenging issues for implementing wireless PHY-security, such as short-distance interception without eavesdropper CSI and with imperfect legitimate CSI. Moreover, the future directions are identified for further enhancement of secrecy performance.

Full-Duplex Relay for Enhancing Physical Layer Security in Multi-Hop Relaying Systems

In this letter, we consider secure communications in multi-hop relaying systems, where full-duplex relays (FDRs) operate to enhance wireless physical layer security. Each FDR is designed to transmit jamming signals to the eavesdropper when it receives information signals from the previous adjacent node. The achievable secrecy rate with the proposed decode-and-forward (DF) FDRs are analyzed with a total transmit power constraint. The transmit power allocation problem is solved by using the geometric programming (GP) method. Numerical results present that the proposed FDRs significantly enhance the secrecy rate compared to the conventional half-duplex relays (HDRs).