Special Issue on: Optical Wireless Communications for Emerging Connectivity Requirements

The Increasing number of smart devices in different forms and capabilities combined with the worldwide adoption of advanced multimedia applications are contributing to the significant growth of the mobile data traffic. The fifth generation (5G) and beyond-5G wireless networks aim at providing wireless connectivity with very high data rates, low latency, high reliability, and scalability, and will support the emerging Internet-of-Things (IoT) applications and services with massively interconnected devices [items 1), 2) in the Appendix]

A review of communication-oriented optical wireless systems

This article presents an overview of optical wireless (OW) communication systems that operate both in the short- (personal and indoor systems) and the long-range (outdoor and hybrid) regimes. Each of these areas is discussed in terms of (a) key requirements, (b) their application framework, (c) major impairments and applicable mitigation techniques, and (d) current and/or future trends. Personal communication systems are discussed within the context of point-to-point ultra-high speed data transfer. The most relevant application framework and related standards are presented, including the next generation Giga-IR standard that extends personal communication speeds to over 1 Gb/s. As far as indoor systems are concerned, emphasis is given on modeling the dispersive nature of indoor OW channels, on the limitations that dispersion imposes on user mobility and dispersion mitigation techniques. Visible light communication systems, which provide both illumination and communication over visible or hybrid visible/ infrared LEDs, are presented as the most important representative of future indoor OW systems. The discussion on outdoor systems focuses on the impact of atmospheric effects on the optical channel and associated mitigation techniques that extend the realizable link lengths and transfer rates. Currently, outdoor OW is commercially available at 10 Gb/s Ethernet speeds for Metro networks and Local-Area-Network interconnections and speeds are expected to increase as faster and more reliable optical components become available. This article concludes with hybrid optical wireless/radio-frequency (OW/RF) systems that employ an additional RF link to improve the overall system reliability. Emphasis is given on cooperation techniques between the reliable RF subsystem and the broadband OW system

Modulation and constrained coding techniques for wireless infrared communication channels

grantor: University of TorontoShort-distance, point-to-point wireless infrared optical links provide a cost-effective means of high speed data transfer between portable devices. To investigate such links, a test-bench and circuits were constructed to determine the limitations of existing optoelectronics. The results of these measurements we used to formulate a signal-space channel model which is employed for the subsequent analysis of candidate bandwidth efficient modulation schemes. The modulation scheme Adaptively Biased QAM (AB-QAM) is developed based on the channel model. AB-QAM provides an asymptotic 3 dB optical SNR improvement over PAM while maintaining the same bandwidth efficiency. The use of constellation shaping is shown to further improve the average optical power efficiency of AB-QAM. This thesis proposes the use of constrained coding techniques to satisfy the non-negativity constraint of the optical channel. These coding techniques are illustrated through an example and contrasted to a baseline case. Constrained coding techniques allow greater flexibility in the choice of pulse shapes used in the channel, leading to possible optical power and bandwidth gains.M.A.Sc

MODULATION AND CONSTRAINED CODING TECHNIQUES FOR MrIRELESS INFRARED COMMUNICATION CHANNELS

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Wireless Optical Communication Systems

xii, 196 hlm.; 23 c