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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.

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.