Indoor optical wireless communications

There has been a growing interest in optical wireless communications for indoor and outdoor applications. The high cost of reconfiguring and maintaining wired networks makes wireless an economical and flexible alternative to wired systems. Lately, two major transmission technologies have been used to achieve indoor wireless communication: RF and infrared. For many reasons, infrared is preferred in certain cases. For example, infrared links provide high bandwidth at low cost, infrared is immune to radio interference, the spectrum is freely available, and infrared components are inexpensive, small and consume little power. This article presents an up-to-date review of the optical wireless communication system features for indoor use. Benefits and limitations of infrared links are explained, as well as advantages and disadvantages of infrared compared to microwave and other radio systems. Design fundamentals and different possible configurations are described. Different sources of infrared noise are explained. Optical safety issues for optical wireless systems are presented. Finally current indoor infrared systems are reviewed, and future trends are visualised.