The Design And Research Of Performance Of Signature Code For OCDMA System

Optical code division multiple access (OCDMA) is a new multiple access multiplexing applying Code Division Multiple Access (CDMA) to optical fiber communications and is one of the technologies for the future free space optical communications, all optical aceess networks and local aera networks. OCDMA is getting more and more attention for its good attributes as high security,soft capacity,synchronous access, convenient networks management,etc,and it has huge potential in communication area,that makes OCDMA one of the hotspot in optical communication. As OCDMA system has the user signals transmitted by optical signals in the whole transmission network except the photoelectric conversion process in the sender and receiver, the OCDMA technology overcome the existence of electronic bottleneck in optical networks and truly realize all-optical communications. But the OCDMA is interference limited system,it is important to design the address codes with large capacity and good relativity.Firstly, in the thesis, a comprehensive overview of OCDMA system is introduced, and the structure principle, characteristics and advantages, and utilities of the core technologies of the network are clarified. In addition, research trends and latest research achievements of OCDMA technology at home and abroad in recent years are introduced. Secondly, the typical one-dimensional codes of the OCDMA system are studied; the construction methods of optical prime codes, quadratic congruential codes (QCC) and optical orthogonal codes are introduced; the characteristics of code are summarized; and the simulation, analysis and comparison results of multiaccess interference bit error rate (BER) are researched. Then,several construction methods of OOC are introduced,.and based on the character of Magic square, a new design method of Magic Square optical orthogonal codes (MS-OOC) is proposed.The method can not only design same weight OOC but also design variable weight OOC. Subsequently, for the problems that one-dimensional OCDMA system can not take full advantage of the effective wavelength of WMOCDMA system, two-dimensional optical orthogonal codes are studied,which have one-coincidence sequence (OCS) the hopping sequence series. And the hopping sequence series new two-dimensional optical orthogonal codes MSPC/OCS are proposed. The new two-dimensional optical orthogonal codes have modified square prime code (MSPC) the time-spreading series, and have one-coincidence sequence (OCS) the hopping sequence series. The code is flexible and simple structure and peforms well. With the virtues, it can not only take full advantage of the effective wavelength of the system, but also easily increase the code capacity.