Research Of Free-Space Optics Access Network Architecture

FSO (Free-space Optics, and is also called Wireless Optical Communication), which is called "wireless fibre optical", is an association of the high-bandwidth qualities of fibre optical and easy-deployed qualities of wireless communication. So Wireless Optics Communications technology has been a feasible interconnect technology for high-capacity communication networks. So telecom corporations have been more and more interested in FSO.In the paper, we focused on the key technology of wireless optics access network to enhance the performance of FSO; After analyzing the architecture of access network, we present a architecture of wireless optical access network, which is compatible with actual communications network; We made primary research in wireless optical access system specification, to let FSO play more and more important role in access network. The main work of this paper is summarized as follows:1) Combing with actual access network, we presented a architecture of wireless optical access network, which can be used in public switched telephone network..2) By analyzing the structure and function module of wireless optical communication optical system, the performance of module was stipulated; Then a budget for selected laser power was made to ensure that the optical link can run reliably.3) In order to enhance wireless optical access system performance, Pulse Position Modulation (PPM) was used to increase the power efficiency, improve the BER. Reed-Solomon (RS)(255,223) code was used to correct the bunched bit error caused by the atmosphere scintillation. And the structure of PPM information frame was stipulated.4) Atmospheric effect on the laser wireless communication link was analyzed. Then, with MATLAB, using the data from long-playing experiment, the atmospheric channel based on PPM signals was obtained.5) Practical standard for wireless optical access system was stipulated. In this standard, physical process and performance of equipment between User Network Interface and Service Node Interface were stipulated.This lesson is souceing from Xi'an university of technoligy's Youth teacher Special features and creative research plan, and the fund of Shannxi province department of education technology .It's also a subject of "Torch Plan", NO: 2002HK52.