High reliability and availability of communication services is a key requirement that needs to be ensured by service providers. Since the direct line-of-sight (LOS) beam is prone to blockage in indoor optical wireless communication systems, a backup link needs to be at hand in case of blockage, and hence channel allocation algorithms should be blockage-aware. In this paper, the impact of beam blockage due to a disc with varying size and distance from the receiver is studied where blockage is quantitatively evaluated using percentage blockage for 512 room locations at 25 cm separation. It was found that assigning two links with maximum separation between the serving access points can reduce or eliminate blockage compared to the case when resilience is not implemented. Increasing the number of allocated access points per user further increases resilience.
School of Mathematics and Statistics, Xi’an Jiaotong University（西安交通大学数学与统计学院）；Department of Electronic and Computer Engineering, Hong Kong University of Science and Technology（香港科技大学电子与计算机工程系）；Hong Kong University of Science and Technology (Guangzhou)（香港科技大学（广州））
IHP – Leibniz-Institut für innovative Mikroelektronik（IHP – 莱布尼茨创新微电子研究所）；Taras Shevchenko National University of Kyiv（基辅塔拉斯·舍甫琴科国立大学）；BTU Cottbus-Senftenberg（科特布斯-森夫滕贝格勃兰登堡工业大学）；Bogomoletz Institute of Physiology（博戈莫列茨生理学研究所）
Resilience aspects of remote electroencephalography sampling are considered. The possibility to use motion sensors data and measurement of industrial power network interference for detection of failed sampling channels is demonstrated. No significant correlation between signals of failed channels and motion sensors data is shown. Level of 50 Hz spectral component from failed channels significantly differs from level of 50 Hz component of normally operating channel. Conclusions about application of these results for increasing resilience of electroencephalography sampling is made.
In this paper, we propose the use of two Passive Optical Network (PON)-based network architectures to connect free-space Optical Wireless Communication (OWC) Access Points (APs) within a room with multiple users. We optimize through a Mixed Linear Integer Programming (MILP) model the assignment of mobile OWC users to more than one AP to improve the resilience of the fronthaul network, i.e the OWC system and the wired network linked to APs, and study the impact of users distribution and channel characteristics.
We demonstrate an LED-based optical wireless link for fixed wireless access applications, at data rates of 1.5 Gbit/s over 50 m. Transmission between indoor equipment and outdoor access point is possible through metal-coated insulation glass.
The requirements in terms of service quality such as data rate, latency, power consumption, number of connectivity of future fifth-generation (5G) communication is very high. Moreover, in Internet of Things (IoT) requires massive connectivity. Optical wireless communication (OWC) technologies such as visible light communication, light fidelity, optical camera communication, and free space optical communication can effectively serve for the successful deployment of 5G and IoT. This paper clearly presents the contributions of OWC networks for 5G and IoT solutions.
The next 5 th generation (5G) and above ultra-high speed, ultra-low latency, and extremely high reliable communication systems will consist of heterogeneous networks. These heterogeneous networks will consist not only radio frequency (RF) based systems but also optical wireless based systems. Hybrid architectures among different networks is an excellent approach for achieving the required level of service quality. In this paper, we provide the opportunities bring by hybrid systems considering RF as well as optical wireless based communication technologies. We also discuss about the key researc…
In this paper, we investigate optical wireless repeaters as relay terminals between a transmitter and a user in an Infrared Optical Wireless Communication (IROWC) system. A delay adaptation method is introduced to solve the problem of irregular signal arrival time from different relay terminals. Three different relay terminal deployment scenarios were investigated in a typical two-phase relay IROWC system with the proposed delay adaptation method. The simulation results indicate that the proposed system has better impulse response compared to the conventional system and that the root-mean-squa…
Quantum Key Distribution (QKD) can guarantee security for practical indoor optical wireless environments. The key challenges are to mitigate artificial lighting and ambient light at the receiver. A new spectral region for QKD is proposed and an ideal QKD link model is simulated with experimental ambient light power measurements. Simulation, modelling, and analysis indicates that the carbon dioxide and water absorption band (1370 nm) is a new wavelength region for QKD operation in indoor optical wireless environments. For a feasible QKD link, approximately 20 dB of signal to noise ratio (SNR) i…
Optical wireless communication is an effective potential solution for enabling high speed next generation cellular networks. In this paper, laser sources, in particular, vertical-cavity surface-emitting (VCSEL) lasers are used for data transmission due to their high modulation speed compared with light emitting diode (LED) sources. To manage multi-user interference, rate splitting (RS) is implemented where the message of a user is split into common and private parts. However, the performance of RS is limited in high density networks. Therefore, hierarchical rate splitting (HRS) particularly su…
The EU COST Action NEWFOCUS is focused on investigating radical solutions with the potential to impact the design of future wireless networks. It aims to address some of the challenges in OWC and establish it as an efficient technology that can satisfy the demanding requirements of backhaul and access network levels in 5G networks. This also includes the use of hybrid links that associate OWC with radiofrequency or wired/fiber-based technologies. The focus of this White Paper is on the use of optical wireless communication (OWC) as enabling technology in a range of areas outlined in HE's Pilla…
Optical wireless communication (OWC) is a promising technology that can provide high data rates while supporting multiple users. The Optical Wireless (OW) physical layer has been researched extensively, however less work was devoted to multiple access and how the OW front end is connected to the network. In this paper, an OWC system which employs a wavelength division multiple access (WDMA) scheme is studied, for the purpose of supporting multiple users. In addition, a cloud/fog architecture is proposed for the first time for OWC to provide processing capabilities. The cloud/fog-integrated arc…
Localization accuracy is of paramount importance for the proper operation of underwater optical wireless sensor networks (UOWSNs). However, underwater localization is prone to hostile environmental impediments such as drifts due to the surface and deep currents. These cause uncertainty in the deployed anchor node positions and pose daunting challenges to achieve accurate location estimations. Therefore, this paper analyzes the performance of three-dimensional (3D) localization for UOWSNs and derive a closed-form expression for the Cramer Rao lower bound (CRLB) by using time of arrival (ToA) an…
In multi-user optical wireless communication (OWC) systems interference between users and cells can significantly affect the quality of OWC links. Thus, in this paper, a mixed-integer linear programming (MILP) model is developed to establish the optimum resource allocation in wavelength division multiple access (WDMA) optical wireless systems. Consideration is given to the optimum allocation of wavelengths and access points (APs) to each user to support multiple users in an environment where Micro, Pico and Atto Cells co-exist for downlink communication. The high directionality of light rays i…
Optical wireless satellite networks (OWSNs) can provide lower latency data communications compared to optical fiber terrestrial networks (OFTNs). The crossover function enables to calculate the crossover distance for an OWSN and an OFTN. If the distance between two points on Earth is greater than the crossover distance, then switching or crossing over from the OFTN to the OWSN results in lower latency for data communications between these points. In this work, we extend the previously proposed crossover function for a scenario such that intermediate satellites (or hops) are incorporated betwee…
The design of a wireless communication system that can support multiple users at high data rates inside an aircraft is a key requirement of aircraft manufacturers. This paper examines the design of an on-board visible light communication (VLC) system for transmitting data on board Boeing 747-400 aircraft. The reading light unit of each seat is utilised as an optical transmitter. A red, yellow, green, and blue (RYGB) laser diode (LD) is used in each reading light unit for transmitting data. An angle diversity receiver (ADR), which is an optical receiver that is composed of four branches (in thi…
Recently, free-space optical (FSO) communication systems have obtained a wide range of applications for communications between unmanned aerial vehicles (UAVs) because they offer several advantages with respect to the traditional RF communication systems. To investigate the performance of UAV-based FSO systems in terms of achievable data rates, we derive the exact closed-form expression for the mean achievable rates of UAV-to-UAV transmission. Our results may serve to investigate the interaction between different FSO system parameters and the average data rates achieved by UAV-based optical wir…
In this communication, we propose a framework for amalgamating optical-orthogonal frequency-division multiplexing (O-OFDM) and O-OFDM with index modulation (O-OFDM-IM) for optical wireless systems. Both schemes individually have some limitations, e.g., O-OFDM does not provide any granularity for spectral efficiency (SE)/energy efficiency (EE) trade-off, and O-OFDM-IM loses EE for higher order modulation alphabets. By combining O-OFDM and O-OFDM-IM together, the above limitations can be circumvented. Following on from providing the general framework, we use asymmetrically clipped (AC)O-OFDM and…
Optical wireless communication offers unprecedented communication speeds that can support the massive use of the Internet on a daily basis. In indoor environments, optical wireless networks are usually multi-user multiple-input multiple-output (MU-MIMO) systems, where a high number of optical access points (APs) is required to ensure coverage. In this work, a laser-based optical wireless network is considered for serving multiple users. Moreover, blind inference alignment (BIA) is implemented to achieve a high degree of freedom (DoF) without the need for channel state information (CSI) at tran…
The ability to provide very high data rates is a significant benefit of optical wireless communication (OWC) systems. In this paper, an optical wireless downlink in a data centre that uses wavelength division multiple access (WDMA) is designed. Red, yellow, green and blue (RYGB) laser diodes (LDs) are used as transmitters to provide a high modulation bandwidth. A WDMA scheme based on RYGB LDs is used to provide communication for multiple racks at the same time from the same light unit. Two types of optical receivers are examined in this study; an angle diversity receiver (ADR) with three branc…
We study security solutions for dual-functional radar communication (DFRC) systems, which detect the radar target and communicate with downlink cellular users in millimeter-wave (mmWave) wireless networks simultaneously. Uniquely for such scenarios, the radar target is regarded as a potential eavesdropper which might surveil the information sent from the base station (BS) to communication users (CUs), that is carried by the radar probing signal. Transmit waveform and receive beamforming are jointly designed to maximize the signal-to-interference-plus-noise ratio (SINR) of the radar under the s…
This article discusses the fundamental architectures for optical wireless systems for biomedical applications. After summarizing the main applications and reporting their requirements, {we describe the characteristics of the transdermal and in-body optical channels as well as the challenges that they impose in the design of communication systems.} In more detail, we provide three possible architectures for transdermal communications, namely electro-optical (EO) monitoring, opto-electrical (OE), and all-optical (AO) for neural stimulation, which are currently under investigation, whereas for in…
Formed by using laser inter-satellite links (LISLs) among satellites in upcoming low Earth orbit and very low Earth orbit satellite constellations, optical wireless satellite networks (OWSNs), also known as free-space optical satellite networks, can provide a better alternative to existing optical fiber terrestrial networks (OFTNs) for long-distance inter-continental data communications. The LISLs operate at the speed of light in vacuum in space, which gives OWSNs a crucial advantage over OFTNs in terms of latency. In this paper, we employ the satellite constellation for Phase I of Starlink an…
Optical wireless Communication (OWC) is a strong candidate in the next generation (6G) of cellular networks. In this paper, a laser-based optical wireless network is deployed in an indoor environment using Vertical Cavity Surface Emitting Lasers (VCSELS) as transmitters serving multiple users. Specifically, a commercially available low-cost VCSEL operating at 850nm wavelength is used. Considering the confined coverage area of each VCSEL, an array of VCSELs is designed to transmit data to multiple users through narrow beams taking into account eye safety regulations. To manage multi-user interf…
In this paper, we design a novel high-throughput random access scheme for an indoor optical wireless communication (OWC) massive Internet of Things (IoT) scenario. Due to the large density of both IoT devices and OWC access points (APs), we base the proposed scheme on multi-receiver coded slotted ALOHA. In this scenario, collisions at APs are resolved by a centralized interference cancellation decoder that may exploit both spatial and temporal diversity. By applying adaptive control of each OWC AP field of view (FOV), the proposed system is able to dynamically adapt to different IoT device act…
Offering a high data rate to users inside the cabin is attractive for the aircraft building companies. This paper presents an optical wireless system that uses visible light for transmitting data. The reading light for each seat is used as a transmitter in this work to offer high data rates. Red, yellow, green, and blue (RYGB) laser diode (LD) are utilised in each reading light to obtain a high modulation bandwidth. Two types of reading lights based on angle diversity transmitter (ADT) units are utilised in this paper for illumination and communication. Additionally, two kinds of optical recei…
This paper presents a comprehensive description of the relative effect of optical underwater turbulence in combination with absorption and scattering. Turbulence induced scattering is shown to cause and increase both spatial and temporal spreading at the receiver plane. It is also demonstrated that the relative impact of turbulence on a received signal is lower in a highly scattering channel. Received intensity distributions are presented confirming that fluctuations in received power from this method follow the commonly used Log-Normal fading model. The impact of turbulence induced scattering…
Interference between cells or users can have a significant impact on the quality of optical wireless communication (OWC) links. This paper studies the co-existence of infrared based Micro cells with Visible light communication based Pico and Atto Cells for downlink communication. The signal to noise ratio (SNR) of each cell and the signal to interference and noise ratio (SINR) between cells are evaluated when an angle diversity receiver and an imaging receiver are used. The results show that Atto cell systems provide higher SNR and data rates compared to the Pico cell systems which provide hig…
Optical wireless communication (OWC) systems have been the subject of attention as a promising wireless communication technology that can offer high data rates and support multiple users simultaneously. In this paper, the impact of room size is investigated when using wavelength division multiple access (WDMA) in conjunction with an angle diversity receiver (ADR). Four wavelengths (red, yellow, green and blue) can be provided in this work based on the RYGB LDs transmitter used. Three room sizes are considered with two 8-user scenarios. A mixed-integer linear programming (MILP) model is propose…
We investigate the asynchronous multiple user access communication in optical wireless scattering communication, where different users transmit signals without perfect alignment in the time domain. Firstly, we characterize the received signal based on hidden markov model (HMM) such that the misalignment among different users can be characterized by the state transition. Then, we investigate the achievable rates based on that of the HMM and obtain the approximated solution using Monte Carlo method. We propose the channel estimation based on expectation-maximization (EM) algorithm. Furthermore, …
We demonstrate a high capacity IF-over-fiber mobile fronthaul solution for multi-user massive MIMO 5G RAN. Using this scheme, a record aggregated radio bandwidth of 25.6 GHz was transmitted on a single optical wavelength over 40 km without fiber chromatic dispersion compensation
The channel modeling of unnamed aerial vehicle (UAV)-based free-space optical (FSO) links with nonzero boresight pointing error is the subject of this paper. In particular, utilizing log-normal turbulence model, we propose a novel closed-form statistical channel model for UAV-based FSO links that takes into account the effect of nonzero boresight pointing errors. Subsequently, utilizing Gamma-Gamma turbulence model, we propose a novel channel characterization for such links that is valid under moderate to strong turbulence conditions. The accuracy of the proposed models is verified via Monte-C…
This paper investigates the asymptotic BER performance of coherent optical wireless communication systems in Gamma-Gamma turbulence when applying the V-BLAST MIMO scheme. A new method is proposed to quantify the performance of the system and mathematical solutions for asymptotic BER performance are derived. Counterintuitive results are shown since the diversity gain of the V-BLAST MIMO system is equal to the number of the receivers. As a consequence, it is shown that when applying the V-BLAST MIMO scheme, the symbol rate per transmission can be equal to the number of transmitters with some cos…
This paper presents a novel massive multiple-input multiple-output (MIMO) transmission in beam domain for optical wireless communications. The optical base station equipped with massive optical transmitters communicates with a number of user terminals (UTs) through a transmit lens. Focusing on LED transmitters, we analyze light refraction of the lens and establish a channel model for optical massive MIMO transmissions. For a large number of LEDs, channel vectors of different UTs become asymptotically orthogonal. We investigate the maximum ratio transmission and regularized zero-forcing precodi…
In recent years, the demand for high speed wireless networking has increased considerably due to the enormous number of devices connected to the Internet. In this context, optical wireless communication (OWC) has received tremendous interest in the context of next generation wireless networks where OWC offers a huge unlicensed bandwidth using optical bands. OWC systems are directional and can naturally provide multiple-input and multiple-output (MIMO) configurations serving multiple users using a high number of transmitters in the indoor environment to ensure coverage. Therefore, multiuser int…
Optical wireless communication (OWC) systems have been the subject of a significant amount of interest as they can be used in sixth generation (6G) wireless communication to provide high data rates and support multiple users simultaneously. This paper investigates the impact of receiver orientation on resource allocation in optical wireless systems, using a wavelength division multiple access (WDMA) scheme. Three different systems that have different receiver orientations are examined in this work. Each of these systems considers 8 simultaneous users in two scenarios. WDMA is utilised to suppo…
Blind source separation is a research hotspot in the field of signal processing because it aims to separate unknown source signals from observed mixtures through an unknown transmission channel. A low computational complexity instantaneous linear mixture signals blind separation algorithm was introduced and improved. There is only one variable parameter named the length of moving average in the algorithm, which has a significant impact on the separation effect. This paper gives some suggestions on the reasonable value through experiments. The algorithm is extended to the separation of visible …
Employing massively distributed antennas brings radio access points (RAPs) closer to users, thus enables aggressive spectrum reuse that can bridge gaps between the scarce spectrum resource and extremely high connection densities in future wireless systems. Examples include cloud radio access network (C-RAN), ultra-dense network (UDN), and cell-free massive multiple-input multiple-output (MIMO) systems. These systems are usually designed in the form of fiber-wireless communications (FWC), where distributed antennas or RAPs are connected to a central unit (CU) through optical front-hauls. A larg…
Air-Sea Surface Modeling and Operating Link Range Evaluation for AUV-to-UAV Optical Wireless Communication Links
Alex Ekwueme Federal University, Ndufu-Alike（艾肯韦梅联邦大学）；Aix Marseille University, CNRS Centrale Méditerranée, Institut Fresnel（艾克斯-马赛大学，法国国家科学研究中心地中海中央学院，费斯尼尔研究所）
Future 6G wireless networks will once again have to raise the capability in most of the technology domains by a factor of 10-100. Depending on the application, future requirements include peak data rates of 1Tb/s per user, 0.1ms latency, less than 1 out of a million outage, centimetre accurate positioning, near zero energy consumption at the device, and operation in different environments including factories, vehicles, and more. Optical wireless communications (OWC) have the potential to provide ultra-high data rates in a cost effective way, thanks to the vast and freely available light spectr…
Free space optical communication has merged the aspects of fiber optics and the wireless communication which are the most conquered and controlled telecommunication technologies. Most of the features of free space optics (FSO) are interrelated to fiber optics but the difference between them is transmission medium, which is glass in case of fiber-optics and air/vacuum in case of FSO. In the near future, communication between LEO & GEO satellites with each other which are orbiting the Earth will be done by using inter-satellite optical wireless communication (IsOWC) systems. IsOWC systems is the…
Location is one of the basic information required for underwater optical wireless sensor networks (UOWSNs) for different purposes such as relating the sensing measurements with precise sensor positions, enabling efficient geographic routing techniques, and sustaining link connectivity between the nodes. Even though various two-dimensional UOWSNs localization methods have been proposed in the past, the directive nature of optical wireless communications and three-dimensional (3D) deployment of sensors require to develop 3D underwater localization methods. Additionally, the localization accuracy…
Photon counting detectors such as single-photon avalanche diode (SPAD) arrays can be utilized to improve the sensitivity of optical wireless communication (OWC) systems. However, the achievable data rate of SPAD-based OWC systems is strongly limited by the nonlinearity induced by SPAD dead time. In this work, the performance of SPAD-based OWC system with orthogonal frequency division multiplexing (OFDM) is investigated and compared with that of on-off keying (OOK). We employ nonlinear equalization, peak-to-average power ratio optimization by adjusting the OFDM clipping level, and adaptive bit …
