The Construction Of Optical Orthogonal Code And The Investigation Of Optical Encoder/Decoder

Code-division multi-access(CDMA) technology has been used in wireless and satellite communications.lt has many advantages such as combating interference, reducing multi-path fading,enchancing system capacity and so on.These advantages cannot be used thoroughtly because of the bound of wireless bandwidth and the environment of transmission. Optical-fiber communications is undisterbed by electromagnetic interference, and they have abundent bandwidth resource. But there is "botttleneck" of photoelectric conversion. OCDMA takes the advantages of both and owns its advantages ,such as no synchronization no complicated route control and network management,transparence to all kinds of messages ,specially account to multimedia communication and high security. So it implies a great challenge for the development of future communication networks,especially all optical networks.In this paper, we do much research in the key-technology of OCDMA.First we compare OCDMA with the main mutiple technology of OTDMA and DWDMA and analyzed the characteristic, capacity and construction methods, iwe put forword a difference matric to predigest the process of soluting autocorrelation and crosscorrelation function. A computer model of autocorrelation and crosscorrelation function was establiched by the difference matrix. A new method of construction of OOC with any code length or code weight was presented for the first time and a SQL data base of code words was founded. We verified the feasibility using fiber delay time, establishing a simulation model by matlab.We set up a testing flat flood by two pathes using fiber delay time. In term of hitting probability and signal-noise ratio ,we analyzed the system's BER performance and derivated some fomulas. According to the character of OCDMA network, we designed topological construction ,media access control method and network protocol. Finnally a New projiect of OCDMA+DWDM was put forward.