一种新的二维光正交码及其性能分析

A New Family of Two-Dimensional Optical Orthogonal Codes and Its Performance Analysis

以光正交码(OOC)作为时间扩频序列,以单重合序列(OCS)作为波长跳频序列,构造了一种新的二维光正交码,即光正交码/单重合序列。与其他二维光正交码相比,光正交码/单重合序列的波长数并不局限于素数或素数幂,可以是任意整数,不仅构造灵活,而且可充分利用多波长光码分多址(MW OCDMA)系统的有效波长数。分析了光正交码/单重合序列码字的自相关和互相关性能,并得到了其互相关均值的具体表达式。最后,针对多波长光码分多址不同的系统参数,对不同参数的光正交码/单重合序列码字性能进行了分析和讨论:1)给定单重合序列参数和光正交码的码重,增加码长将降低光码分多址系统误码率;2)给定光正交码的参数和单重合序列的码长,增加波长数将降低光码分多址系统误码率。

A new two-dimensional （2D） optical orthogonal code （OOC） constructed using OOC for time spreading and one-coincidence sequence （OCS） for wavelength hopping named OOC/OCS is presented. Compared with other 2D OOC, the number of wavelengths for OOC/OCS is not limited to a prime number or its power. OOC/OCS can be constructed flexibly, and also can use available wavelengths adequately. Auto-correlation and cross-correlation performances of OOC/OCS are analyzed, and the mean value of cross-correlation is also deduced. In the end, the performance of OOC/OCS with different parameters is analyzed and discussed, according to different parameters of multi-wavelength optical code division multiple access （MW OCDMA） system. Given OCS and code weight w, bit error ratio （BER） of OCDMA system is decreased when code length L is increased. Given OOC and code length N, BER of OCDMA system is decreased when the number of wavelengths is increased.