色散对光CDMA传输系统性能的影响

Impact of dispersion on the performance of optical CDMA transmission system

基于耦合非线性薛定谔方程分析了光CDMA传输系统中光纤色度色散对传输性能的影响,给出了考虑色度色散系数r后光BER的表达式,使得对系统BER的理论分析更加有效.数值计算结果显示,r=0.4时7码片M-序列系统在10-9的BER时功率衰减4.8dB;并进一步表明,对功率衰减6dB的31码片M-序列系统,当r=0.4时,同时使用的用户不超过24个,而r=0.6时,使用的用户不超过20个.指出色度色散对单极性光码分多址系统性能的影响较大,在相同情况下,r越大,接入用户数越少.

The impact of fiber chromatic dispersion on the BER （ bit error rate） performance of a direct sequence optical code-division multiple-access （COMA） system is analyzed based on the coupled nonlinear Schrcdinger equation （CNLSE）. The presented to evaluate considering the expression r of the chromatic dispersion, which will be good for the analysis of the BER. The numerical results show that the system suffers a power penalty of 4. 8 dB corresponding to chromatic dispersion index r =0. 4 for seven-chip M-sequence, at a BER of 10^-9. It is further noticed that the number of simultaneous users are limited to 24 for r = 0. 4 and 20 for r = 0.6, for 31-chip M-sequence, at 6 dB power penalty. The result presents that the performance of monopole code-division multiple-access system impacted by chromatic dispersion is the worst. It shows that the bigger the r, the less the user accessed under same conditions.