Study On Indoor Visible Light MIMO Communications System Based On White Leds

White LED offers advantageous properties, such as high brightness, reliability, lower power consumption and long lifetime. White LEDs are expected to serve in the next generation of lamps. With the growing shortage of energy and environmental issues appear., it is hoped that these devices are used not only for illuminating rooms but also for an optical wireless communication system. Therefore, visible light communications are presented.Nowadays, one of the major challenges in visible light communications is the low modulation bandwidth which available from devices. There are large number of approaches to improve the modulation bandwidth, including using a blue-filter at the receiver to filter out the slow-response yellowish components, pre-equalization at the LED driving module, post-equalization at the receiver or a combination of these techniques. Another challenge is to achieve Gbit/s transmission rates using a VLC link. So we propose multiple input multiple output (MIMO) VLC. The use of MIMO techniques offers the potential for increased link range and higher data throughput without the need of additional power or bandwidth, meanwhile, improve link reliability and higher spectral efficiency.This thesis introduces the general theory of visible light communication, and a discussion of the indoor visible light communication system performance under multiple reflections, also, analyzing the system optical power penalty caused by multi-path dispersion.Secondly, we introduce the MIMO techniques into visible light communication, in order to improve the communication rate. We investigate general model of non-imaging and imaging visible light MIMO communication systems. We simulate and analyze the non-imaging visible light MIMO communications system performance.Finally, we design indoor communication architecture of imaging optical MIMO communication system, give the system parameters, such as, the distance between transmitter and receiver, focal length and the diameter of the imaging lens, the size of the photosensitive surface and so on.