基于变码重光正交码光码分多址系统的性能分析

Investigation on Performance of OCDMA System Based on Variable-weight Optical Orthogonal Codes

光正交码是一种具有良好自相关性和互相关性的(0,1)序列,被广泛的运用于光码分多址(OCDMA)系统.由于光正交码中所有码字的码重都固定不变,使得码字的容量不大.我们提出了变码重光正交码,并对其进行了理论分析.最后,给出了数值仿真结果.结果表明,采用变码重光正交码的系统无论是在可接入用户数还是在系统误码率上都优于采用固定码重光正交码的系统.研究结果对OC-DMA系统参数的选取具有一定的参考价值.

An optical orthogonal code（OOC） is a family of （0,1） sequences with good auto-and cross-correlation properties and is widely used in optical code division multiple access（OCDMA） system. But the capacity of OOC is very small. The reason is that the weight of each codeword is the same. In this paper, the variable--weight OOC which can provide large codeword is presented. Furthermore, the performance of variable-weight OOC in optical CDMA system is also analysed. At last, numerical simulations are carried out. The results show that in terms of the number of users or the bit error rate（BER）,the performance of system which uses variable-weight OOC is better than that of using OOC. The findings provide some reference value for the OCDMA system parameter selection.