摘要
从码字的非周期互相关函数出发,分析异步相干扩时光码分多址(OCDMA)系统的多址干扰(MAI)和差拍噪声(BN)。干扰用户不同的传输时延,非周期互相关强度均值随之变化,差拍噪声和多址干扰也随之变化。给出了差拍噪声和多址干扰与非周期互相关强度均值的关系,讨论了异步相干扩时OCDMA系统的误码率(BER)与非周期互相关强度均值的关系。最后,以码长511的Gold码为例,针对干扰用户之间不同的传输时延,得到了异步相干扩时OCDMA系统的误码率上界与平均误码率性能。在平均误码率情况下,OCDMA系统能支持12个干扰用户,而在最差情况下(误码率上界),系统容纳的干扰用户数不超过4个。
Multiple-access interference （MAI） and beat noise （BN） in coherent time-spreading optical code-division multiple access （OCDMA） system are analyzed according to aperiodic cross-correlation function. The mean intensity of aperiodic cross correlation depends on the transit delay of interfering users, and MAI and BN will change with the mean intensity of aperiodic cross-correlation accordingly. The relationship between the mean intensity of aperiodic cross-correlation and MAI and BN is deduced, and then the relationship between the bit error rate （BER） and the mean intensity of aperiodic cross-correlation is discussed for coherent time-spreading OCDMA. For Gold sequence with the length N = 511, mean and upper bound of BER performances are derived according to the different transit delay of the interfering users in coherent time-spreading OCDMA system. In the case of mean BER performance, OCDMA system can support about 12 interfering users. However, for the worst case （upper bound of BER）, OCDMA system can support no more than 4 interfering users.
出处
《中国激光》
EI
CAS
CSCD
北大核心
2008年第12期1878-1882,共5页
Chinese Journal of Lasers
基金
国家自然科学基金(60772027)资助项目
关键词
光通信
光码分多址
多址干扰
差拍噪声
非周期互相关函数
optical communication
optical code division multiple access
multiple-access interference
beat noise
aperiodic cross-correlation function
