Optical Wireless Communication Network Research Articles

On the Physical Layer Security of Underwater Optical Wireless Communication Networks

On the Physical Layer Security of Underwater Optical Wireless Communication Networks

Fluid-responsive tunable metasurfaces for high-fidelity optical wireless communication.

Optical wireless communication (OWC), with its blazing data transfer speed and unparalleled security, is a futuristic technology for wireless connectivity. Despite the significant advancements in OWC, the realization of tunable devices for on-demand and versatile connectivity still needs to be explored. This presents a considerable limitation in utilizing adaptive technologies to improve signal directivity and optimize data transfer. This study proposes a unique platform that utilizes tunable, fluid-responsive multifunctional metasurfaces offering dynamic and unprecedented control over electromagnetic wave manipulation to enhance the performance of OWC networks. We have achieved real-time, on-demand beam steering with vary-focusing capability by integrating the fabricated metasurfaces with different isotropic fluids. Furthermore, the designed metasurfaces are capable of polarization-based switching of the diffracted light beams to enhance overall productivity. Our research has showcased the potential of fluid-responsive tunable metasurfaces in revolutionizing OWC networks by significantly improving transmission reliability and signal quality through real-time adjustments. The proposed methodology is verified by designing and fabricating an all-dielectric metasurface measuring 500 μm × 500 μm and experimentally investigating its fluid-responsive vary-focal capability. By incorporating fluid-responsive properties into spin-decoupled metasurfaces, we aim to develop advanced high-tech optical devices and systems to simplify beam-steering and improve performance, adaptability, and functionality, making the devices suitable for various practical applications.

A Quantum-Behaved Heterogeneous Topology Optimization Model For Optical Wireless Communication Networks

A Quantum-Behaved Heterogeneous Topology Optimization Model For Optical Wireless Communication Networks

Augmentation of spectral efficiency in optical wireless communication networks using grid‐based elephant swarm optimization protocol

SummaryThe emergence of 5G and 6G technologies has resulted in a faster, more automated, and more intelligent data flow in the digital world. A wide spectrum of optical wireless communication is made available to support 5G and 6G technologies, and it can meet the demands of high‐speed optical wireless communication. Trade‐offs involving latency, power consumption, deployment costs, and hardware/computational overhead have always been a part of 5G/6G technologies. The decline in the trade‐offs indicated above has major implications for networking capacity. The proposed work modulated a new grid‐based communication protocol (GCP) with elephant swarm optimization (ESO) to surpass those issues with optical wireless communication devices. This protocol employs an integrated strategy to split the network and choose the cluster head effectively. Different GCP‐ESO‐related algorithms have been explored. Various components of the OSNs, including network energy usage, cluster, and non‐cluster header nodes, are also calculated using mathematical analysis. The results have been simulated using MATLAB software. The simulation precisely demonstrates that the proposed GCP‐ESO outperforms the emerging MCH‐EOR and RDSAOA‐EECP methods concerning energy consumption (0.46 J), packet loss ratio (PLR) (0.60%), end‐to‐end latency (11.0 s), packet delivery rate (PDR) (99.41%), routing (0.112), the lifetime of the network (3718 s), and throughput (0.989 Mbps).

A novel distributed multi-slot TDMA-based MAC protocol for LED-based UOWC networks

Underwater optical wireless communication (UOWC) networks are promising for many civilian and industrial applications due to underwater high-speed data transmission demand. This paper focuses on the distributed time division multiple access (TDMA) protocol design for UOWC networks. Unlike existing research, we focus on a more general underwater communication scenario where nodes are scattered, and node mobility is considered. We propose a distributed TDMA-based medium access control(MAC) protocol, called cluster-based cross-layer multi-slot MAC(CCM-MAC), which can assign multiple slots to each node according to the slot-occupying information. When using CCM-MAC, the network is divided into clusters. Each node maintains knowledge of the cluster topology and slot-occupying information of surrounding nodes through routing techniques; by updating this knowledge, collisions can also be detected and eliminated dynamically. Analysis results are presented to evaluate the performance of CCM-MAC, and simulations show that high network throughput and low collision rate can be realized in comparison with existing contention-based MAC protocols.

The Security in Optical Wireless Communication: A Survey

With the demand for economical and high-speed wireless services, Optical Wireless Communication (OWC) has attracted increasing attention in both research and the market. In the past decades, numerous optical-related techniques (e.g., LEDs, displays, cameras) and systems (e.g., VLC, LiFi, LiDAR) have been invented. OWC techniques, which are considered as a competitive mechanics in next-generation networks as an alternative to RF approaches, offer 10,000 times more bandwidth than conventional radio frequency (RF)-based wireless techniques (e.g., WiFi, LoRa, Bluetooth, LTE), as well as tremendous spatial reuse potential with even less interference. Because optical communications have a limited wavelength and travel in the line of sight (LoS) manner, the OWC is commonly thought as a secure wireless approach to confine light transmissions within physical bounds. However, in the real world, it is completely untrue. The privacy leakages and security risks broadly exist in the optical-related wireless applications including OWC networks. These threats and weaknesses have recently been the subject of several initial studies. However, they lack systematic analysis and are isolated. This survey first presents a general workflow of OWC systems, which consists of three stages: before signal emission (BSE), during signal propagation (DSP), and after signal receiving (ASV). For each stage, related risks are reviewed. Then, we summarize existing attacks in optical-related wireless applications and corresponding counter-attack solutions. Finally, we outline the future trends for improving OWC security.

Recent Development of Emerging Indoor Wireless Networks towards 6G

Sixth-generation (6G) mobile technology is currently under development, and is envisioned to fulfill the requirements of a fully connected world, providing ubiquitous wireless connectivity for diverse users and emerging applications. Transformative solutions are expected to drive the surge to accommodate a rapidly growing number of intelligent devices and services. In this regard, wireless local area networks (WLANs) have a major role to play in indoor spaces, from supporting explosive growth in high-bandwidth applications to massive sensor arrays with diverse network requirements. Sixth-generation technology is expected to have a superconvergence of networks, including WLANs, to support this growth in applications in multiple dimensions. To this end, this paper comprehensively reviews the latest developments in diverse WLAN technologies, including WiFi, visible light communication, and optical wireless communication networks, as well as their technical capabilities. This paper also discusses how well these emerging WLANs align with supporting 6G requirements. The analyses presented in the paper provide insight into the research opportunities that need to be investigated to overcome the challenges in integrating WLANs in a 6G ecosystem.

On the UOWC Performance Under Location Uncertainty

More often than not, currents due to gravity, wind friction, and heterogeneous water density cause frequent drifts of the end-users to random locations creating transmission problems in an underwater optical wireless communication (UOWC) network. The location uncertainty effect on the overall network performance in harsh environments, including submarine ones, is an appealing issue that needs to be adequately addressed in the existing technical literature. The present work takes account of a vertical UOWC link where a fixed transmitter at the sea surface illuminates towards the seabed following a Lambertian pattern. In this way, a randomly placed receiver inside a spherical cone is served, and the problem is treated with three-dimensional stochastic geometry methods. In the sequel, the complete statistical behavior of the random distributions of the channel gain and the instantaneous electrical signal-to-noise ratio is estimated. Moreover, some critical network performance metrics, including the outage probability and the bit-error rate for intensity modulation/direct detection with on-off keying and <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">M</i> -ary pulse position modulation, are derived, whereas indicative numerical results are illustrated adequately through a series of appropriate figures.

Digital RIS (DRIS): The Future of Digital Beam Management in RIS-Assisted OWC Systems

Reconfigurable intelligent surfaces (RIS) have been recently introduced to optical wireless communication (OWC) networks to resolve skip areas and improve the signal-to-noise ratio at the user’s end. In OWC networks, RIS are based on mirrors or metasurfaces. Metasurfaces have evolved significantly over the last few years. As a result, coding, digital, programmable, and information metamaterials have been developed. The advantage of these materials is that they can enable digital signal processing (DSP) techniques. For the first time, this paper proposes the use of digital RIS (DRIS) in OWC systems. We discuss the concept of DRIS and the application of DSP methods to the physical material. In addition, we examine metamaterials for optical DRIS with liquid crystals serving as the front row material. Finally, we present a design example and discuss future research directions.

Simultaneous lightwave information and power transfer in optical wireless communication networks: An overview and outlook

Objectives:The main objective of this article is to provide a critical review of up-to-date contributions to simultaneous lightwave information and power transfer (SLIPT) in optical wireless communication (OWC) networks. Methods:The first section of this article emphasizes the need for the exploitation of optical signals for energy harvesting purposes in order to develop a sustainable OWC system. In the second section, we provide basic guidelines to be considered for designing an efficient SLIPT system. In the third section, SLIPT structure from the viewpoint of transceiver architecture is analyzed with respect to achievable rate and harvested energy. The fourth section provides a critical review of various articles on SLIPT in OWC networks. Results:Our main findings from the analysis in section three show that receiver diversity can be achieved using multiple photodetectors. Consequently, this leads to an improved achievable rate and harvested energy of the SLIPT receivers. Also, based on the limitations of papers presented in section four, we are able to unlock several open issues and potential solutions that can be explored as future research areas. Conclusions:SLIPT is considered to be a key promising technique that can be used in developing green OWC networks. In this article, the performance of SLIPT receivers and various articles on SLIPT-related designs have are presented. Based on the transceiver analysis, limitations and design challenges of the articles presented, several areas that can be explored for future research work are identified. Thus, more contributions are still needed toward developing efficient SLIPT-based systems.

6LoWPAN Over Optical Wireless Communications for IPv6 Transport in Internet of Things Networks

As an emerging technology for the Internet of Things (IoT) wireless connectivity, there have been a lot of research and standardization activities on Visible Light Communications (VLC) and Optical Wireless Communications (OWC) using Light Emitting Diode (LED) lights. In the meantime, the Internet Protocol version 6 (IPv6) over Low Power Wireless Personal Area Network (6LoWPAN) has been discussed to provide the IPv6-based IoT services in wireless networks. However, the study on IoT systems using 6LoWPAN over OWC networks has not been made so far. This letter proposes a new architectural model to effectively use 6LoWPAN between IoT gateway and IoT device in the OWC-based IoT networks. The proposed model is easy to implement and provides the performance enhancement in OWC-based IoT networks, compared to the general IPv6 model. From testbed experimentations, it is shown that the proposed model provides the delay gain up to 5% and the throughput gain up to 19.52%, compared to the conventional IPv6 transport model.

Bit Error Performance of APD and SPAD Receivers in Optical Wireless Communication

This review concentrates on the state-of-the-art hardware-oriented receiver aspects for optical wireless communication (OWC), and points to the importance of BER performance analysis and modeling in presence of non-perpendicular light incidence. Receivers in OWC networks for 6G applications have to work for strongly different light incidence angles, to allow the formation of connections to locally separated transceivers without the need for rotation units and accurate adjustment. In turn, and in combination with fully integrated optical receivers, reduction of cost and increased comfort can be achieved. Fully integrated [bipolar] complementary metal-oxide-semiconductor ([Bi]CMOS) receivers with on-chip avalanche photodiodes (APDs) and single-photon avalanche diodes (SPADs) are presented and their performance in optical wireless communication is summarized. Impressive data rates up to 2 Gbit/s and free-space transmission distances up to 27 m at bit error ratios (BER) below 10−9 are reached with linear-mode APD receivers. The importance of optical interference in the isolation and passivation stack on top of the integrated photodiodes is illuminated. To be able to predict the dependence of the BER of single-photon avalanche diode (SPAD) receivers on the light incidence angle, a model, which includes a model for the photon detection probability and a standing-wave model for the isolation and passivation stack, is extended. The dependence of the BER on the light incidence angle onto the photodiodes is investigated by electromagnetic simulation for optical transmission of the layers on top of the photodiode, device simulation for the avalanche triggering probability and BER modeling with MATLAB. It is found that incidence angles up to 30° have moderate influence on the BER and that the BER degrades significantly for incidence angles larger than 50°.

Performance Analysis of Hybrid Radio Frequency and Free Space Optical Communication Networks with Cooperative Spectrum Sharing

This paper investigates the impact of cooperative spectrum sharing policy on the performance of hybrid radio frequency and free space optical wireless communication networks, where primary users and secondary users develop a band of the same spectrum resource. The radio frequency links obey Nakagami-m distribution with arbitrary fading parameter m, while the free space optical link follows gamma-gamma distributed atmospheric turbulence with nonzero pointing error. Because the secondary users access the spectrum band without payment, their behavior needs to be restricted. Specifically, the power of the secondary users is dominated by the tolerable threshold of the primary users. Considering both heterodyne and intensity modulation/direct detection strategies in optical receiver, the performance of optical relaying networks is completely different from that of traditional networks. With the help of bivariable Fox’s H function, new expressions for cumulative distribution function of equivalent signal to noise ratio at destination, probability density function, outage probability, ergodic capacity and symbol error probability are built in closed forms.

The effects of Tx./Rx. pointing errors on the performance efficiency of local area optical wireless communication networks

Abstract This study presents the effects of Tx./Rx. pointing errors on the performance efficiency of local area optical wireless communication networks. The received signal power and max Q factor are measured in the presence of vertical-cavity surface-emitting lasers (VCSELs) bias current and modulation current at maximum propagation distance for the wireless network. The signal is enhanced with increasing of bias and modulation peak currents of the VCSEL device. The optimum received power and max. Q factor is also examined at Tx./Rx. the pointing error of 0.1 mrad and propagation reach of 5 km at available bit rates transmission of 10 Gb/s.

Performance Analysis of Inter-satellite Optical Wireless Communication (IsOWC) System with Multiple Transmitters/Receivers

The satellite communications networks have certainly been innovated recently by Inter-satellite optical wireless communication (IsOWC) networks. The prerequisite for next generation mobile satellite communication is superior multimedia facility for consumers at anytime and anywhere. The proposed optical communication system is designed and analysed to improve data transmission quality over the distance between two geostationary (GEO) satellites greater than 36000 km. This trend is to achieve high speed transmission with minimizing the presence possibility of free space loss in transmission that can occur in satellite communication via the longest range. Numerous transceivers IsOWC is a hopeful way to deal with be utilized related to different earth stations as a system utilized between the geosynchronous satellites. The wireless transmission creates the opportunity at high optical power without free space loss. The results of the simulated system showed that with 32 transmitters/receivers IsOWC, the Q-factor values of 36.526, 12.176 and 4.015 are obtained at 38000 km range at laser power of (19, 14 and 9) dBm, respectively. The proposed system is operated at 19 dBm optical power and different values of aperture size and the best values of Q-factor and BER are 41 and 10−250, respectively, for highest diameter value of 20 cm. The operation of the system with various values of bit rate is verified as well. It is seen that the best system performance is at 0.032 Gb/s bit rate and will be of lower as the bit rate increases until it roughly fixes at 32 Gb/s. This research offers the treatment for the transmission problem for ultra-speed application in mobile satellite systems.

FD-OMAC: A Novel Full-Duplex Optical Media Access Control for IEEE 802.15.7

Optical wireless communication (OWC), the IEEE 802.15.7 standard (revised 2018) is developed in normative reference to low-rate wireless personal area networks IEEE 802.15.4 standard. One significant difference between the two standards is the highly directional transmitters in the OWC networks. This difference opens up the possibility of adding full-duplex communication to wireless networks. Our work proposes adding full-duplex functionality in the contention-free period (CFP) of the OWC media access control (MAC) layer. We justify the significance of our proposal by implementing IEEE 802.15.7 resource allocation scheme for both our proposed full-duplex optical MAC (FD-OMAC) and the IEEE 802.15.7 MAC. Our simulation results demonstrate that the proposed work improves the spectral efficiency in the CFP without compromising delays. We also discuss the minor changes required in the IEEE 802.15.7 MAC for implementing FD-OMAC. We further extend the FD-OMAC to a multiple access point network and evaluate its performance in comparison with IEEE 802.15.7 MAC.

Channel Characterization and Realization of Mobile Optical Wireless Communications

Link instability induced by users’ mobility is one of the challenges of optical wireless communications (OWC) inherited from the propagation nature of light. Hence, good understanding of the optical channel characteristics in dynamic environments plays a vital role in developing robust resource management strategies in OWC networks. Unfortunately, it is quite difficult to collect accurate indoor optical channel data in dynamic environments. In addition, indoor trajectory dataset is not publicly available. To overcome such limitations, this paper proposes a mobile terminal-centric analytical framework that captures the propagation channel characteristics in a mobile OWC network whose downlink is based on visible light and uplink is based on infrared light. We abstract the nature of human behavior by integrating both macro and micro mobility patterns. These patterns are then used to realize the spatio-temporal characteristics of optical wireless channels under long-term environment-confined mobility. The statistics derived from the developed framework indicate that the mobile line-of-sight (LOS) channel gain follows space-time-dependent multiple-peak Nakagami distributions, whereas the non-line-of-sight (NLOS) channel gain adheres to various space-time-dependent single peak distributions under different indoor layouts. The overall distribution of NLOS bandwidth follows space-time-dependent multiple-peak log-logistic distributions in downlinks and space-time-dependent generalized log-logistic distributions in uplinks. Our investigation demonstrates that the indoor layout and the user’s environment-confined mobility pattern significantly impact the LOS dynamics but present limited impact on NLOS components. Motivated by the need for better channel models for mobile OWC, the proposed framework fills up an important gap in literature and help the research community to understand better the indoor optical wireless channel characteristics.

Vector Rayleigh Diffraction of High-Power Laser Diode Beam in Optical Communication

Laser diodes (LDs) are widely used in optical wireless communication (OWC) and optical networks, and proper theoretical models are needed to precisely describe the complicated beam field of LDs. A novel mathematical model is proposed to describe the vectorial field of nonparaxial LD beams. Laser beam propagation is studied using the vector Rayleigh diffraction integrals, and the stationary phase method is used to find the asymptotic expansion of diffraction integral. The far-field distribution of the LD beam in the plane parallel and perpendicular to the junction is considered in detail, and the computed intensity distributions of the theory are compared with the corresponding measurements. This model is precise for single transverse model beam of LDs and can be applied to describe the LD beams in OWC and optical networks.

Analysis of 2 × 10 Gbps MDM enabled inter satellite optical wireless communication under the impact of pointing errors

Technological advancement in Optical Wireless Communication has led the race to harvest such a novel technique which is capable of providing higher data rates and at the same time lower power consumptions. To provide more cost effective solution and immunity to various losses, the use of mode division multiplexing (MDM) technique is proposed. In this work, 2 independent channel each having unique mode is used to carry non return zero (NRZ) encoded data of 10 Gbps each on inter-satellite optical wireless communication (Is-OWC) network. The impact of pointing errors is also studied in this work. The result are presented in form of BER and Eye Diagrams.

Spectrum sensing in optical wireless communication network

AbstractThe main focus of this paper is on the issue of spectrum sensing or channel awareness in an optical wireless scattering communication network. We propose two spectrum sensing algorithms to detect M‐ary pulse‐position modulation signal under Poisson channel statistic. The first algorithm premises on symbol‐by‐symbol block processing, in which the photon‐counting receiver collects the received photons during a symbol interval and a Neyman‐Pearson decision rule is developed to determine the optimum decision threshold, whereas the second algorithm is based on chip‐level sequential as well as diversity detection. Performances of both algorithms are extensively analyzed in terms of the detection probability, the false alarm probability, the average detection delay, and the average false alarm run length. Simulation results demonstrate that scheme 2 outperforms scheme 1 under different scenarios. We also analyze the existing algorithm on the considered signal model and verify the effectiveness of the proposed algorithms over existing spectrum sensing algorithm.