Optical wireless communication (OWC) is an excellent complementary solution to its radio frequency (RF) counterpart. OWC technologies have been demonstrated to be able to support high traffic generated by massive connectivity of the Internet of Things (IoT) and upcoming 5 th generation (5G) wireless communication systems. As the characteristics of OWC and RF are complementary, a combined application is regarded as a promising approach to support 5G and beyond communication systems. Hybrid RF/optical and optical/optical wireless systems offer an excellent solution for recovering the limitations of individual systems as well as for providing positive features of each of the technologies. An RF/optical wireless hybrid system consists both RF and optical-based wireless technologies, whereas an optical/optical wireless hybrid system consists two or more types of OWC technologies. The co-deployment of wireless systems can improve system performance in terms of throughput, reliability, and energy efficiency of individual networks. This study surveys the state of the art and key research directions regarding optical wireless hybrid networks, being the first extensive survey dedicated to this topic. We provide a technology overview of existing literature on optical wireless hybrid networks, such as RF/optical and optical/optical systems. We consider the RFbased macrocell, small cell, wireless fidelity, and Bluetooth, as well as optical-based visible light communication, light fidelity, optical camera communication, and free-space optical communication technologies for different combinations of hybrid systems. Moreover, we consider underwater acoustic communication for hybrid acoustic/optical systems. The opportunities brought by hybrid systems are presented in detail. We outline important challenges that need to be addressed for successful deployment of optical wireless hybrid network systems for 5G and IoT paradigms.
Communications based solely on radio frequency (RF) networks cannot provide adequate quality of service (QoS) for the rapidly growing demands of wireless connectivity. Since devices operating in the optical spectrum do not interfere with those using the RF spectrum, wireless networks based on the optical spectrum can be added to existing RF networks to fulfill this demand. Hence, optical wireless communication (OWC) technology can be an excellent complement to RF-based technology to provide improved service. Promising OWC systems include light fidelity (LiFi), visible light communication, optical camera communication (OCC), and free-space optical communication (FSOC). OWC and RF systems have differing limitations, and the integration of RF and optical wireless networks can overcome the limitations of both systems. This paper describes an LiFi/femtocell hybrid network system for indoor environments. Low signal-to-interference-plus-noise ratios and the shortage bandwidth problems of existing RF femtocell networks can be overcome with the proposed hybrid model. Moreover, we describe an integrated RF/optical wireless system that can be employed for users inside a vehicle, remote monitoring of ambulance patients, vehicle tracking, and vehicle-to-vehicle communications. We consider LiFi, OCC, and FSOC as the optical wireless technologies to be used for communication support in transportation, and assume macrocells, femtocells, and wireless fidelity to be the corresponding RF technologies. We describe handover managementincluding detailed call flow, interference management, link reliability improvement, and group handover provisioning-for integrated networks. Performance analyses demonstrate the significance of the proposed integrated RF/optical wireless systems.
The demand for autonomous vehicles is increasing gradually owing to their enormous potential benefits. However, several challenges, such as vehicle localization, are involved in the development of autonomous vehicles. A simple and secure algorithm for vehicle positioning is proposed herein without massively modifying the existing transportation infrastructure. For vehicle localization, vehicles on the road are classified into two categories: host vehicles (HVs) are the ones used to estimate other vehicles' positions and forwarding vehicles (FVs) are the ones that move in front of the HVs. The FV transmits modulated data from the tail (or back) light, and the camera of the HV receives that signal using optical camera communication (OCC). In addition, the streetlight (SL) data is considered to ensure the position accuracy of the HV. Determining the HV position minimizes the relative position variation between the HV and FV. Using photogrammetry, the distance between FV or SL and the camera of the HV is calculated by measuring the occupied image area on the image sensor. Comparing the change in distance between HV and SLs with the change in distance between HV and FV, the positions of FVs are determined. The performance of the proposed technique is analyzed, and the results indicate a significant improvement in performance. The experimental distance measurement validated the feasibility of the proposed scheme. Keywords-Vehicle localization, vehicle-to-vehicle communication, vehicle-to-infrastructure communication, optical camera communication, photogrammetry.
Currently, various radio frequency (RF) technologies are used to transfer medical data in healthcare applications. The electromagnetic interference caused by RF can critically affect the performance of medical devices. The main goal of this paper, thus, is to provide reliable and low-latency fifth-generation (5G) electronic health (eHealth) solutions for monitoring patients at home, hospitals, ambulances, intensive care units, and outdoors. This monitoring is based on optical camera communication (OCC). In our proposal, the OCC system is used to receive the monitored data from wearable sensors/patches. OCC systems are connected to 5G access networks or wired networks to be linked with the core network. The proposed system is able to provide fast and secure connectivity for simultaneous monitoring of multiple patients. The monitored information is forwarded to hospitals, medical servers, doctors, cloud, and mobile systems for remote monitoring purposes. In this study, we provide a novel technical solution for monitoring patients remotely. A robot system with OCC is also proposed to monitor the health data of multiple patients in hospital. We provide several eHealth solution scenarios for better understanding of the proposed eHealth architecture. UPCOMING FIFTH-GENERATION (5G) communication systems are able to bring enormous evolution in the field of information and communication technology (ICT). 1 The 5G Public Private Partnership (5GPPP) aiming for new 5G-enabled markets in the fields of intelligent transport, smart cities, entertainment, media, electronic health (eHealth), and education. Commercialization of 5G is expected to have a huge impact on the implementation of eHealth systems. According to the World Health Organization (WHO), 2, 3 eHealth is the use of ICT for health. ICT-based devices, apparatus, and facilities are included in eHealth systems, and they enhance the performance of the medical sector by providing excellent monitoring, diagnosis, medication, prevention, and management systems. The use of ICT for healthcare can benefit the whole community by improving the system for access to care and quality of care. An eHealth system includes real-time remote monitoring of patients, exchanging medical records among patients, expert physicians, and health service providers through hub of medical information networks, recording patient health information and storing eHealth records on the cloud, providing remote monitoring and diagnosis facilities, provision of global access of medical data, monitoring patients remotely in and outside hospitals, and robotized patient monitoring and surgery. 4-6 Various services offered by eHealth systems can improve medical facilities and help in the decision-making process. eHealth solutions can be effectively used in every aspect of our lives. 5G communication is essential for the This article has been accepted for publication in a future issue of this journal, but has not been fully edited. Content may change prior to final publication.
Optical camera communication (OCC) exhibits considerable importance nowadays in various indoor camera based services such as smart home and robot-based automation. An android smart phone camera that is mounted on a mobile robot (MR) offers a uniform communication distance when the camera remains at the same level that can reduce the communication error rate. Indoor mobile robot navigation (MRN) is considered to be a promising OCC application in which the white light emitting diodes (LEDs) and an MR camera are used as transmitters and receiver respectively.
Localizing smartphones in indoor environments offers excellent opportunities for ecommence. In this paper, we propose a localization technique for smartphones in indoor environments. This technique can calculate the coordinates of a smartphone using existing illumination infrastructure with light-emitting diodes (LEDs). The system can locate smartphones without further modification of the existing LED light infrastructure. Smartphones do not have fixed position and they may move frequently anywhere in an environment. Our algorithm uses multiple (i.e., more than two) LED lights simultaneously. The smartphone gets the LED-IDs from the LED lights whose are within the field of view (FOV) of the smartphone's camera. These LED-IDs contain the coordinate information (e.g., x-and y-coordinate) of the LED lights. Concurrently, the pixel area on the image sensor (IS) of projected image changes with the relative motion between the smartphone and each LED lights which allows the algorithm to calculate the distance from the smartphone to that LED. At the end of this paper, we present simulated results for predicting the next possible location of the smartphone using Kalman filter to minimize the time delay for coordinate calculation. These simulated results demonstrate that the position resolution can be maintained within 10 cm. Keywords-Indoor localization, optical camera communication (OCC), image sensor (IS), photogrammetry, and Kalman filter.Both industry and academic research institutes have recently shown interest in the issue of indoor smartphone localization, and various schemes have been proposed [2], [3]. The most common and widely used indoor localization system relies on the global positioning system (GPS) [4]. Moreover, this system has three particular limitations (e.g., poor GPS signal reception, loss of GPS signal, and limited localization accuracy) [5] especially in indoor environments. This system is not suitable for underground or indoor localization. Since the signal from the satellites to a receiver should be line-of-sight (LOS), and building, soil, water, trees or even poor weather conditions inhibits this signal. Time of flight (TOF) cameras are another possible candidate for solving the localization scheme [6]. Besides its advantages, this system is too expensive and sometimes requires complex scenarios for implementation which makes it inappropriate for unique approach. TOF camera also has some other drawbacks, it is only useful for detection and ranging purposes and does not facilitate the communication purpose [7]. Received signal strength indication (RSSI), time of arrival (TOA), time difference of arrival (TDOA), angle of arrival (AOA) are physical parameters of radio signal that can be used for localization with special distributed monitors [8], [9]. Other approaches used for indoor localization include computer vision (CV) and artificial intelligence (AI) [10]. None of these approaches are ideal for indoor localization. For example, RSSI depends on environmental conditions. It is affected by shad...
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