Two-dimensional Ocdma Communication System

Optical code division multiplexing access (OCDMA) is one of the possibleresolutions for future all optical communication network,which is a hot topic inoptical communication research.Compared with other multiplexing technologies,itis still at the state of infancy.The main research of this paper is focused on two dimension optical codedivison multiplexing access system.Two dimensional code is encoded in time andwavelength or time and space domain, so the performance of two dimensionOCDMA system is better than one dimension OCDMA system.It can accommodatemore user simultaneously than one dimension OCDMA system and the implement ismore easier than bipolar OCDMA system.Firstly, the basic principle, system schemes and the key technologies areintroduced.The development, research status and trends of OCDMA technologiesare also summarized. Combining with other multiplexing technologies and usingfiber gratings as the encoder/decoder are the trends of OCDMA system.The sorts and architectures of two dimension OCDMA systems are investigatedin the second section. Optical Fast Frequency-Hop CDMA system based onencoder/decoder of FBG is investigated by simulation. Results show that the systemhas preferable performance of the matched filtering. It is easily implemented andthe wavelengths transmitted can be controlled. This system is one of the promisingoptical CDMA systems.The performance of two dimension OCDMA system is analyzed in the thirdsection. The upper-bounds on BER of OCDMA system using the timespreading/wavelength hopping codes is investigated with or without using theoptical hard limiter.The thorough investigation and analysis on the performances ofthe system is performed by simulation and it gets some valuable results.Theperformance of two dimension OCDMA system considering receiver noises isanalyzed and results is gotten for the first time.Two typical system of two dimensionOCDMA systems are compared by simulation.At last, suggestion of improving theperformance of two dimension OCDMA system is summarized.On the demand of the multirate transmission in OCDMA network,we advancea multirate two dimension OCDMA system using paralled structure in the forthsection.By analyse and simulation,wo can see the syetem overcome thedisadvantage of tranditional OCDMA system and all the users use the sameencoders and decoders,so it simplified the implement of system.The summarization of all the paper is got in the last section.