Channel modeling for visible light communications—a survey

Abstract

Visible light communication (VLC) is a newly emerging technology, which integrates communications and lighting purposes, and has become a very active research topic in the areas of wireless communications. It is expected to become an important part of the next generation wireless communications because of its unique features in using unlicensed spectrum, support of high data rate, and its resistance to electromagnetic interferences. In this survey paper, we begin with a review on the basis of photometry, which is used to establish channel models of VLC systems. Then, we will continue to address various issues on the fundamental characteristic features of VLC systems, the impact of indoor environments on system performance, and the analysis and discussions of five different types of typical VLC channel models and other related parameters in VLC channel models. Finally, in terms of the future works, we will show the possible follow-up research focuses and directions as an effort to identify some new research topics on VLCs. Visible light communicationsFigure 1. Diagram of current spectrum resource usage.authorities and spectrum usage fees. On the other hand, the electromagnetic spectrum bands in RF is fairly limited and controlled strictly by the regulatory authorities, resulting in a high cost of usage and maintenance of the RF spectral resources. Meanwhile, VLC supports high data rate optical communications and facilitates the bandwidth reuse. Therefore, VLC can be employed to support very high data rate wireless communications [10][11][12][13][14][15][16][17].Second, VLC is much securer than RF communications. Transmission medium of VLC is visible light, which cannot penetrate walls and other non-transparent objects in an indoor environment, and thus, its transmission is limited in the line of sight (LOS). This means that the transmission of user data information is confined to a room, and it is much more difficult for eavesdroppers to intercept communication content without being noticed by the senders in the same room. In this way, transmission of data information can be carried out effectively without external malicious interceptions, and security of information can be ensured. Therefore, VLC offers a highly confidential means of wireless communications particularly suitable for military and other secure information communication applications [12][13][14][15][16][17][18][19]. In millimeter wave communications, the wireless signal attenuation is rapidly near 60 GHz, but its security is by far not as good as VLC systems [20].Third, VLC is not hazard to human health. We can use a higher transmission power in VLC if it is needed than normal RF communications. Compared with infrared and ultraviolet communication technologies, VLC can be implemented in a more comfortable way because of human eyes visual perception nature, and thus, it allows us to use a greater transmission power in order to improve communication link quality [12][13][14][15].In addition, VLC in visible lightwave bands, which are quite different fr...

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