Study On The Communication Performances Of 2D WDM/OCDMA Hybrid System

Optical code division multiplexing access(OCDMA)is one of the possible resolutions for future all optical communication network,which is a hot topic in the field of optical communication research.Compared with other multiplexing technologies,it is still at the state of infancy.This thesis mainly discussed some issues of two-dimension WDM/OCDMA hybrid systems,including the design of address codes: single code sequences optical orthogonal codes and double code sequences m sequence;the realization of encoder and decoder and the performances of two receiver modules,and had obtained several achievements as follows:(1)Studying on address codes:1D OOC and 2D OOC which have good characters,meanwhile the capacity of OOC is analyzed and simulated, and the capacity of 2D OOC is much larger;the bit error rate of 1D OOC and 2D OOC is also simulated when WDM/OCDMA hybrid system is only effected by multiple access interference,and the simulation shows that the bit error rate of 2D OOC method is much better.(2)Three schemes of 2D OCDMA is studied and each of the upper bound bit error rate is given,also WDM/OCDMA and multiple wavelength OCDMA is compared,the results show that WDM/OCDMA is obviously better,but its capacity is relatively smaller than MW OCDMA under the condition of the same code lengths and code weights.(3)Due to narrow band interference between WDM users in WDM/OCDMA hybrid system,a new receiver module is introduced,that is adding aπshifted phase equipment,and the results show that NBI is completely suppressed,bit error rate is reduced and the performance of the hybrid system is improved further.(4)In noncoherent 2D WDM/OCDMA hybrid system,other than MAI, beat noise is also considered,the bit error rate is deduced and simulated. The results show that the shorter response time of PD the better performance is achieved.(5)In coherent Spectral Phase Encoding WDM/OCDMA hybrid system,nonlinear receiver based on second harmonic generation effect is analyzed in detail,so SH signal with different energy is carded by expected signals and MAI signals,and expected signals can be easily separated from MAI,the bit error rate is reduced further and the performance of WDM/OCDMA hybrid system is improved.At the same time,coherent SPE,nocoherent 2D WDM/OCDMA and nocoherent 1D scheme is compared,simulations show that coherent scheme is the best,this is because the weight of m sequence is much larger than single code sequences' and the weight is contributed most to improve the hybrid system performance.