针对单极性码在光码分多址系统应用中存在正交性和用户容纳能力较差的缺点,对采用双极性地址码的光谱幅度编码系统中接收端采用差分检测的方案进行了研究.讨论了用于差分频谱幅度编码方案中的地址码应满足的条件,对OOK和双极性编码系统方案,在考虑散弹噪声和热噪声的条件下,分析了误码率性能.通过数值计算,比较了"1"和"0"都发信号的系统和只有"1"发信号的系统性能.比较结果表明,双极性地址码方案可提高系统性能;另外,提高光功率还可改善系统性能.

In order to improve the relatively poor orthogonality and capacity for more users in OCDMA system,which uses the single polarity code,the differential check scheme on the receiver side of the spectrum encoding OCDMA system with the bipolarity codes is studied.The condition,which should be met by the address code used for the differential spectrum amplitude encoding scheme,is discussed.The bit error rate of the OOK and the bipolarity encoding scheme is analyzed with chirp and Johnson-Nyquist noise taken into account.Through the numerical calculation,the performance comparison between one system(that both "one" and "zero"represent the signals) and another system(that only "one" represents the signals) was made.The results show that the scheme of the bipolarity address code and the higher laser power can improve the system performance.