Visible light communication system

Abstract

LED lightings are expected to serve in the next generation of lamps. Compared with the conventional lighting methods, white LEDs offer the advantageous properties of lower power consumption, and long lifetime. White LED based indoor lighting systems have been predicted to become the predominant method used for illuminating indoor spaces within the next decade or so.

In this report, an indoor visible light wireless communication system utilizing white LED lighting equipment is presented. In this system, the LED lighting devices are used not only for illuminating rooms but also for a wireless optical communication system. This dual function of LED, for lighting and communication, is creating many new and interesting applications. The function is based on the fast switching of LEDs and the modulation of the visible light waves for free-space communications.

Then, various communication schemes in indoor visible light environment are introduced and discussed. A diversity technique is proposed so that shadowing problem may be alleviated. Moreover, to overcome the inter-symbol interference caused by optical path difference between lighting equipments, an adaptive equalizer is proposed and discussed.

Finally, a Diversity-MIMO channel switching technique for light communication is proposed. This system can also be considered as a hybrid system that utilizes the advantages of the two systems to alleviate shadowing and alignment problems.

From these proposals, it is found that the idea of the proposed systems is very promising for future high speed wireless networks and visible light wireless communication can be one choice for an indoor optical wireless data transmission system.