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Introduction: Optical Wireless Communication Systems
Published in Z. Ghassemlooy, W. Popoola, S. Rajbhandari, Optical Wireless Communications, 2019
Z. Ghassemlooy, W. Popoola, S. Rajbhandari
The growing amount of data generated by the IoT, big data, and cloud usage will fill the existing communication capacity. Thus, the more critical question is whether the telecommunication infrastructure can keep up with the pace and the service providers can increase the transmission capacity if all the channels are fully occupied by the signal spectrum. In access networks, the technologies currently in use include the copper and coaxial cables, wireless internet access, broadband RF/microwave, and optical fibre. These technologies—in particular, copper and coaxial cables and broadband RF/microwave—have limitations, such as a congested spectrum, a lower data rate, expensive licensing, security issues, and a high cost of installation and accessibility to all. In fixed fibre communications, high data rates (i.e., 100–400 Gbps per fibre) have been reported based on multilevel modulation formats [4], [5]. Higher data rates (tens of Tbps and beyond) have also been reported by employing space division multiplexing (SDM) technologies [6], [7]. The dense wavelength division multiplexing (WDM) has been used extensively to increase the data rate for long-haul transmission. Alternative options are the deployment of new fibres right down to the “last mile” access networks, which is the most costly and time consuming. Another option would be to increase the transmission speed at the cost of higher bandwidth consumption per fibre, provided the signal bandwidth remains within recommended 50 GHz ITU grids.
Networks Fundamentals and Present Architectures
Published in Iannone Eugenio, Telecommunication Networks, 2017
The access network is the part of the network connecting the access central offices to the users‘ physical locations. This is the most branched part of the network, penetrating in metropolitan roads and reaching far into the countryside. The scope of the access network is one directional-to collect the signal generated from the end users and convey it to the peripheral network elements, located in the access central offices and in the other direction to deliver the signal from the central office network elements to the destination customer.
Introduction Optical Wireless Communication Systems
Published in Z. Ghassemlooy, W. Popoola, S. Rajbhandari, ®, 2017
Z. Ghassemlooy, W. Popoola, S. Rajbhandari
We are seeing a growing demand for bandwidth in mobile communication, as the number of users is increasing significantly. The next-generation wireless communication systems therefore should be able to offer higher capacity to support various broadband wireless services such as the high-definition TV (HDTV—4–20 Mbps), computer network applications (up to 100 Mbps), mobile videophones, video confer-encing, high-speed Internet access, and so on. In access networks, the technologies currently in use include the copper and coaxial cables, wireless Internet access, broadband radio frequency (RF)/microwave and optical fibre. These technologies, in particular copper/coaxial cables and RF based, have limitations such as a congested spectrum, a lower data rate, an expensive licensing, security issues and a high cost of installation and accessibility to all. Optical wireless communications (OWC) is an age-long technology that entails the transmission of information-laden optical radiation through the free-space channel. OWC technology is one of the most promising alternative schemes for addressing the ‘last mile’ bottleneck in the emerging broadband access markets. OWC offers a flexible networking solution that delivers the truly broadband services. Only the OWC technology provides the essential combination of virtues vital to bring the high-speed traffic to the optical fibre backbone. That is offering a license-free spectrum with almost an unlimited data rate, a low cost of development and ease and speediness of installation. This chapter gives an overview of the OWC systems for indoor and outdoor applications as a complementary technology to the existing schemes. The rest of the chapter is organized as follows. Section 1.1 outlines the wireless access technologies, followed by a brief history of OWC in Section 1.2. The comparative study of the optical and RF spectrum is summarized in Section 1.3. The link configuration and applications of the OWC are given in Sections 1.4 and 1.5. The eye safety issues are covered in the last section.
Network resource optimization configuration in edge computing environment
Published in International Journal of Computers and Applications, 2023
Yong Liu, Jiabao Jiang, Yun Liu, Yong Zhang, Qilin Wu
The core architecture of the edge computing is as shown in Figure 1, which includes a three-layer structure of a radio access network a backbone network, and a cloud data center. The terminal connects to the network operator through the radio access network, and the operator accesses the network provider through the backbone network. The cloud service provider deployment serves the backbone network. By deploying the MEC service in the vicinity of the mobile terminal, the mobile terminal connects the computing task to the intelligent base station from the cloud through the wireless access network provided by the network operator through the intelligent base station. When the intelligent base station cannot meet the current mobile terminal requirements, the mobile terminal passes through the core. The network connects to the cloud data center to obtain data, which achieves a win-win effect of reducing the terminal computing response delay and reducing the backbone network load.
SCAN-CogRSG: Secure Channel Allocation by Dynamic Cluster Switching for Cognitive Radio Enabled Smart Grid Communications
Published in IETE Journal of Research, 2022
For SG communication, wireless technologies such as ZigBee, IEEE 802.11ah, IEEE 802.11af, and IEEE 802.22 (TV White Space) have been utilized [24,25]. From those technologies, IEEE 802.22 (CRN standard) hash many advantages like communication range (up to kilometers), data rate, and spectrum utilization. As shown in Figure 1, the CRN will be the better solution for establishing communication in NANs and HANs. CRN has proven its effectiveness in many Internet of things (IoT) applications [26]. However, in SG communications, security plays a pivotal role [27,28]. In general, SG communications are subjected to false data injection attack, malicious user access attack, spoofing attack, and so on. In CRN-based SG communications, unauthorized and malicious user access results in a huge spectrum loss, which degrades the entire network performance. CRN-based SG communications must be optimized with the following development: Optimal channel allocation for handling increasing spectrum demandSecurity improvements to prevent the SG system from malicious user accessNetwork management to handle the large-scale network
ACO–OFDM with Improved Bandwidth Efficiency over Long Haul and MIMO Optical Fiber Communication Systems
Published in IETE Journal of Research, 2022
Optical fiber has been an efficient transmission channel for high speed and long haul communication link up to transoceanic distances. It holds enormous data speed capacity with low environmental interferences. Basic optical fiber set-up consists of single-mode fibers for long distance high speed links where as multimode fiber is a low cost option for short distance, slower data rate applications [1]. Optical fiber links are backbone for links between telephone exchanges, Cable TV connections and base stations to remote node terminals in radio over fiber. Recent challenges for communication industry are related to network and device designing that can sustain for upcoming advancements in technologies and demands on user end. Cloud radio access network (C-RAN) for 5G requires a fair investment in point-to-point fiber link closer to the user end [2–4].