Enhancing Physical Layer Security Research Articles

Editorial

Welcome to the inaugural volume of Comm&Optics Connect, a multidisciplinary journal dedicated to advancing communication and networks across the entire electromagnetic spectrum. This first volume embodies our vision to provide a platform where groundbreaking research in radio, mmWave, THz, and optical technologies converges. The future of communication networks lies in the seamless integration of technologies across the electromagnetic spectrum to support ultra-high speed, ultra-low latency, and massive connectivity. However, realizing this vision requires overcoming significant challenges, such as managing the complexity of heterogeneous networks, ensuring robust security and privacy, and developing energy-efficient solutions. Comm&Optics Connect addresses these challenges by offering a platform for radio, mmWave, THz, and optical fields to share their work and collaboratively tackle these issues. The response to our call for papers reflects a strong interest in contributing to the aims and scope of the journal. The five articles featured in this volume represent the breadth and depth of research that Comm&Optics Connect aims to showcase. These articles cover critical areas such as: • Real-Time Cloud-based IoT for Energy Consumption Monitoring: Damien Campbell et al. present a cloud-based IoT platform for monitoring household electricity consumption, providing valuable insights into usage patterns and identifying opportunities for enhancing energy efficiency. This research exemplifies the journal’s focus on practical deployments. • Free Space Optical Inter-Satellite Links: Shivam Bhutiani and Nupur Shah explore the establishment of free space optical inter-satellite links beyond the Karman line. This work highlights the journal’s interest in cutting-edge communication technologies for space applications, aligning with the increasing demand for high-speed and reliable connectivity in satellite networks. • Enhancing Physical Layer Security: Shen Qian and Meng Cheng delve into physical layer security in lossy untrusted relay networks, focusing on the challenges and opportunities presented by finite blocklength transmissions. This research contributes to the journal’s commitment to exploring security and resilience in communication systems, an area of paramount importance as networks become more complex and vulnerable. • Open Fronthaul Technologies for 5G and Beyond: Hamna Shoukat et al. provide a comprehensive overview of technological trends in open fronthauls for beyond 5G and 6G networks. This work highlights the journal's emphasis on next-generation networks and the critical role of open and interoperable architectures in fostering innovation and flexibility. • Multi-Task Learning for Low-Complexity VLC Systems: Saksham Dewan and Hany Elgala explore the application of multi-task learning to reduce the complexity of visible light communication (VLC) systems. This research exemplifies the journal’s dedication to exploring novel data-driven approaches using deep learning (DL) models for enhanced efficiency and performance. As the Editor-in-Chief of Comm&Optics Connect, I am confident that the journal will become an essential resource for researchers in the field of communications and networks. None of this would be possible without the outstanding and diverse members of the editorial board, the hard-working staff at Scifiniti, and the valuable reviewers. I invite you to join us on this exciting journey as we bridge the gap between cutting-edge research and practical applications, shaping the future of a connected world. We look forward to receiving contributions from all over the world.

Enhancing Physical Layer Security in WPCNs With IRS and Controlled Jamming for 6G IoT Applications

Enhancing Physical Layer Security in WPCNs With IRS and Controlled Jamming for 6G IoT Applications

Enhancing physical layer security via information hiding and chaotic frequency-hopping signal

Enhancing physical layer security via information hiding and chaotic frequency-hopping signal

Enhancing Physical Layer Security With RIS Under Multi-Antenna Eavesdroppers and Spatially Correlated Channel Uncertainties

Enhancing Physical Layer Security With RIS Under Multi-Antenna Eavesdroppers and Spatially Correlated Channel Uncertainties

Enhancing Physical Layer Security of Cooperative Nonorthogonal Multiple Access Networks via Artificial Noise

The massive connectivity requirement and security issues have become major factors restricting the further development of the Internet of Things. Nonorthogonal multiple access (NOMA) can be combined with physical layer security (PLS) to achieve massive connectivity and secure transmission. This article investigates the PLS performance for a downlink communication system over Nakagami-m fading channels, with full-duplex (FD) cooperative NOMA transmission aided by artificial noise (AN). While direct communication is built between the base station and two NOMA users, the strong user is employed as an FD relay as well as the jammer to enhance the PLS of the legitimate transmission in the presence of a passive eavesdropper (Eve). Closed-form analytical expressions in terms of the outage probability of the legitimate users and the intercept probability of Eve are derived to evaluate the security–reliability trade-off (SRT) of the proposed scheme. Monte Carlo simulations are provided to validate the veracity of the theoretic analyses and illustrate that the proposed scheme is superior in terms of SRT to the benchmark schemes in the low SNR region. Furthermore, the results reveal that the SRT performance of the two NOMA users can be enhanced through a proper AN-bearing ratio and power allocation optimization.

Enhancing Physical Layer Security in MIMO Systems through Beamforming and Artificial Noise Techniques

Physical layer security (PLS) has grown in popularity as it guarantees secure and reliable communication between wireless devices without restricting the ability of data analysts to eavesdrop. PLS benefits from the randomization property of the wireless channel, which improves immunity and protects against many dangers of information breaches from eavesdroppers. MIMO and Massive MIMO, which use numerous antennas at the transmitter and receiver ends, are fundamental technologies for improving efficiency in 5G and future network systems. The PLS still requires a significant amount of work before it can be employed in practical systems. The interception of eavesdroppers can be made difficult by adding artificial noise. This paper focuses on the physical layer security considering maximal ratio combining, and artificial noise with beamforming techniques to further enhance the secrecy rate. The proposed work demonstrates that the use of transmitter beamforming with artificial noise can significantly improve the degree of confidentiality of information being transmitted between a transmitter and an intended receiver while making it more difficult for eavesdroppers to intercept. The simulation results in terms of bit error rate show that the proposed method has a significant impact on the error rate performance of the eavesdropper.

A Learning Based Framework for Enhancing Physical Layer Security in Cooperative D2D Network

Next-generation wireless communication networks demand high spectrum efficiency to serve the requirements of an enormous number of devices over a limited available frequency spectrum. Device-to-device (D2D) communication with spectrum reuse offers a potential solution to spectrum scarcity. On the other hand, non-orthogonal multiple access (NOMA) as a multiple-access approach has emerged as a key technology to re-use a spectrum among multiple users. A cellular users (CUs) can share their spectrum with D2D users (DUs) and in response, the D2D network can help relay the CU signal to achieve better secrecy from an eavesdropper. Power optimization is known to be a promising technique to enhance system performance in challenging communication environments. This work aimed to enhance the secrecy rate of the CUs where the D2D transmitter (DT) helps in relaying the CU’s message under the amplify and forward (AF) protocol. A power optimization problem is considered under the quality of service constraints in terms of minimum rate requirements at the receivers and maximum power budgets at the transmitters. The problem is a non-convex complex optimization. A deep learning-based solution is proposed and promising results are obtained in terms of the secrecy rate of CU and the rate of D2D users.

Artificial-Noise-Aided Space–Time Line Code for Enhancing Physical Layer Security of Multiuser MIMO Downlink Transmission

We consider secure downlink multiple-input–multiple-output (MIMO) communications between a transmitter and multiple users when there exists a passive eavesdropper. A downlink main channel between the transmitter and a user is estimated through uplink pilot symbols in a time-division duplex mode. On the other hand, to hinder an eavesdropper from estimating the eavesdropper channel between the transmitter and the eavesdropper, the transmitter does not send any pilot symbols. The main channel is hence available at the transmitter only, while the eavesdropper channel is unavailable at any node. Assuming these channel state information (CSI) conditions, we propose a MIMO transmission method using space–time line code (STLC) with artificial noise (AN) for enhancing the physical layer security. The STLC enables noncoherent detection at the receiver, i.e., a user, without CSI and achieves full spatial diversity. We derive the lower bound of the secrecy sum rate for the proposed STLC transmission method without AN, with AN, and with AN and imperfect CSI. Moreover, numerical results verify that the proposed STLC scheme outperforms the conventional eigen-beamforming and the precoding space-time block code in terms of secrecy sum rate regardless of the signal-to-noise ratio, the number of transmit antennas, and the CSI uncertainty.

Enhancing physical layer security via a UAV friendly jammer for NOMA‐based IoT systems with imperfect CSI

AbstractIn this article, we investigate physical layer security in downlink Internet of Things networks under imperfect channel state information (CSI), in which a controller (Alice) intends to serve two user devices (D1 and D2) simultaneously by using nonorthogonal multiple access (NOMA). Cooperative jamming (CJ) is introduced as a powerful solution for guaranteeing secure transmission. To be specific, we integrate an unmanned aerial vehicle (UAV) jammer that generates artificial noise to confuse multiple noncolluding eavesdroppers (Eves). Considering only D1 requires secure transmission, we develop an adaptive power allocation scheme to maximize the secrecy rate at D1 while meeting the desired quality of service (QoS) threshold at D2. Furthermore, a strategy can be utilized to obtain the optimal location of the UAV jammer is derived for further performance enhancement. Besides, we also examine the impact of the channel uncertainties on system performance. Numerical results are provided to confirm the superiority and applicability of the proposed CJ scheme over benchmark schemes in terms of secrecy performance and effective energy efficiency.

Enhancing Physical Layer Security of Random Caching in Large-Scale Multi-Antenna Heterogeneous Wireless Networks

In this paper, we propose a novel secure random caching scheme for large-scale multi-antenna heterogeneous wireless networks, where the base stations (BSs) deliver randomly cached confidential contents to the legitimate users in the presence of passive eavesdroppers as well as active jammers. In order to safeguard the content delivery, we consider that the BSs transmits the artificial noise together with the useful signals. By using tools from stochastic geometry, we first analyze the average reliable transmission probability (RTP) and the average confidential transmission probability (CTP), which take both the impact of the eavesdroppers and the impact of the jammers into consideration. We further provide tight upper and lower bounds on the average RTP. These analytical results enable us to obtain rich insights into the behaviors of the average RTP and the average CTP with respect to key system parameters. Moreover, we optimize the caching distribution of the files to maximize the average RTP of the system, while satisfying the constraints on the caching size and the average CTP. Through numerical results, we show that our proposed secure random caching scheme can effectively boost the secrecy performance of the system compared to the existing solutions.

Enhancing Physical Layer Security Performance in Downlink Cellular Networks through Cooperative Users

Enhancing Physical Layer Security Performance in Downlink Cellular Networks through Cooperative Users

Enhancing Physical Layer Security in Internet of Things via Feedback: A General Framework

In this article, a general framework for enhancing the physical layer security (PLS) in the Internet of Things (IoT) systems via channel feedback is established. To be specific, first, we study the compound wiretap channel (WTC) with feedback, which can be viewed as an ideal model for enhancing the PLS in the downlink transmission of IoT systems via feedback. A novel feedback strategy is proposed and a corresponding lower bound on the secrecy capacity is constructed for this ideal model. Next, we generalize the ideal model (i.e., the compound WTC with feedback) by considering channel states and feedback delay, and this generalized model is called the finite state compound WTC with delayed feedback. The lower bounds on the secrecy capacities of this generalized model with or without delayed channel output feedback are provided, and they are constructed according to variations of the previously proposed feedback scheme for the ideal model. Finally, from a Gaussian fading example, we show that the delayed channel output feedback enhances the achievable secrecy rate of the finite state compound WTC with only delayed state feedback, which implies that feedback helps to enhance the PLS in the downlink transmission of the IoT systems.

Enhancing Physical Layer Security for Cooperative Non-Orthogonal Multiple Access Networks with Artificial Noise

Enhancing Physical Layer Security for Cooperative Non-Orthogonal Multiple Access Networks with Artificial Noise

Two-Stage Relay Selection for Enhancing Physical Layer Security in Non-Orthogonal Multiple Access

In this paper, we examine the physical layer security of a cooperative relay network where two source-destination pairs communicate through a decode-and-forward (DF) relay in the presence of multiple eavesdroppers. To safeguard the legitimate communications against eavesdropping, we propose a novel two-stage secure relay selection (TSSRS) with a non-orthogonal multiple access (NOMA) scheme to maximize the capacity of one source-destination pair, while guaranteeing the successful communication of the other source-destination pair. To explicitly reveal the benefits of our proposed scheme, we derive the exact and asymptotic expressions for its secrecy outage probability. As a benchmark, we also analyze the secrecy performance of the TSSRS strategy with an orthogonal multiple access (OMA) scheme. Both theoretical analysis and simulation results demonstrate that our proposed TSSRS-NOMA scheme significantly outperforms the TSSRS-OMA scheme when the transmit power at the source and relay is in the low and medium regimes. In addition, we show that the advantage of the TSSRS-NOMA scheme over the TSSRS-OMA scheme becomes obvious when the two source-destination pairs have profoundly different secrecy requirements.

Enhancing Physical Layer Security of DF Buffer-Aided Relay Networks With Small Buffer Sizes

In this paper, we propose a novel max-weight secure link selection (MWSLS) scheme to enhance physical layer security of decode-and-forward (DF) buffer-aided relay networks. The MWSLS scheme can select the link with the largest weight among all secure and available source-to-relay and relayto-destination links. By modeling the dynamic buffer state transitions as a Markov chain, we derive the closed-form expressions of the secrecy outage probability, the secrecy diversity gain, the average secrecy throughput and the end to end delay, which provide a comprehensive and effective way to evaluate the impacts of different parameters on the secrecy performance. The results of this paper reveal that: 1) For the case with small buffer sizes, a significant enhancement on the secrecy outage performance can be observed compared with the popular max-link secure link selection (MLSLS) scheme. 2) When L ≥ 3, the secrecy diversity gain of the system can achieve 2M, while the MLSLS scheme achieves the same secrecy diversity gain only when L → ∞ (where M denotes the number of relays and L is the buffer size). 3) The MWSLS scheme outperforms the MLSLS scheme in terms of the average secrecy throughput and the end to end delay in the low signal-to-noise ratio (SNR) regime, and obtain the same performance as the latter in the high SNR regime.

Energy-Constrained SWIPT Networks: Enhancing Physical Layer Security With FD Self-Jamming

In this paper, we investigate the secrecy performance of energy-constrained wireless-powered networks with considering the passive eavesdropping scenario, where the simultaneous wireless information and power transfer-based full-duplex self-jamming (SWIPT-FDSJ) scheme is developed. The maximal ratio transmission protocol is applied at the multi-antenna source such that the wireless signals are designated to the destination directly. Besides, the energy harvesting and full-duplex self-jamming operations are adopted at the energy-constrained destination to prolong its lifetime as well as to confuse the eavesdropper. Specifically, the exact and asymptotic closed-form expressions of the connection outage probability (COP), the secrecy outage probability (SOP), and the secrecy throughput of the proposed system are obtained, based on which we optimize the time-switching ratio to maximize the secrecy throughput. We also degenerate the proposed SWIPT-FDSJ scheme to the reduced half-duplex with no self-jamming (HDNSJ) scheme. The finds suggest that in the HDNSJ scheme, adding the antenna number of the source only benefits the COP performance, but has no impact on the SOP performance. By contrast, it will promote the COP and SOP performance at the same time in the SWIPT-FDSJ scheme, which eventually results in the great improvement of secrecy throughput. In addition, we present the practical application condition of the SWIPT-FDSJ scheme. It is demonstrated that the secrecy throughput performance of the SWIPT-FDSJ scheme is much superior to the HDNSJ scheme on condition that the application condition is satisfied.

Adaptive OFDM‐IM for Enhancing Physical Layer Security and Spectral Efficiency of Future Wireless Networks

In this paper, we propose algorithms for enhancing physical layer security and spectral efficiency of Orthogonal Frequency Division Multiplexing (OFDM) with Index Modulation (IM) systems. Particularly, different activation ratios and/or Constellation Modulation orders are selected adaptively for each subblock based on the channel quality of the legitimate receiver. More specifically, three approaches named as (1) OFDM with Adaptive Index Modulation and Fixed Constellation Modulation (OFDM‐AIM‐FCM), (2) OFDM with Adaptive Index Modulation and Adaptive Constellation Modulation (OFDM‐AIM‐ACM), and (3) OFDM with Variable Index Modulation and Variable Constellation Modulation (OFDM‐VIM‐VCM) are proposed for enhancing physical layer security and spectral efficiency. Simulation results are presented to investigate the effectiveness of the proposed algorithms.

Enhancing physical-layer security via big-data-aided hybrid relay selection

The explosive growth in data traffic presents new challenges to the new generation of wireless communication systems, such as computing capabilities, spectrum efficiency and security. In this paper, we use the network structure, which is adaptable for the big data traffic, to improve the security of wireless networks. Specifically, a big-data aided hybrid relay selection scheme is designed and analyzed to enhance physical layer security. First, considering the ideal situation that an eavesdropper’s CSI (Channel State Information) is known to the legal nodes, we propose an optimal hybrid relay selection scheme consisting of the optimal mode selection scheme and the optimal relay selection scheme. In this case, we analyze the upper bound of an eavesdropper’s capacity in FD (Full-Duplex) mode and the secrecy outage probabilities of the optimal HD (Half-Duplex), FD, and hybrid relay selection schemes. Through the analysis of data, it is clear that the mode selection is decided by the self-interference of the FD technique. However, the instantaneous CSI of an eavesdropper is difficult to obtain due to the passive characteristic of eavesdroppers in practice. Therefore, a more practical hybrid relay selection scheme with only the channel distribution information of an eavesdropper is further studied, where a weighting factor is employed to guarantee that the hybrid mode is no worse than either the FD mode or HD mode when the self-interference grows. Finally, the simulation results show the improved security of our proposed scheme.