Study On Beam Auto-selection Shemes For Wireless Communication Systems

With the modern progress made in wideband wireless communications, office automatic system, and intelligent appliances, the communication system with ever-higher capacity and speed is in great demand, which result in the technology of indoor wireless optical communications become big concern. In wireless communication systems, comparing with traditional radio bands, optical bands has the advantage of high transmission capacity and interference resistance. Due the factors of people mobility, and light signal reflection off walls, the ceiling, tables, the floor, etc, the quality of transition deteriorate highly, even has the possibility to break off the link. Therefore, the study on techniques for link improvement to enhance performance of the wireless optical communication systems is extremely significant. The idea of an optimum path existed in the optical signal transmission for the wireless optical communication which was proposed by A. H. Khanshan in 2002, Arguing that it can reduce the system power loss and improve the performance. This thesis investigates how to select the optimum path based on this foundation.Our focus is on the schemes for selecting an optimal path, of which a realization is herein presented. This scheme self-selects the transmitter beam according to the receiver's correlation value. We analyze the performance improvement from our system with beam auto-selection over a quasi-diffuse system, under either an ideal channel or a multipath channel with background noise, simulated by using MATLAB program.The background light noise is a primary factor that affecting the system performance. We further analyze the performance of a beam auto-selection system with diversity receiving techniques, in the presence of shot noise from fluorescent illumination. Simulation results verify that its superior mitigation of the background noise.