CO-OFDM系统中利用阈值功率点改进的后向传输补偿算法

采用后向传输(BP)补偿算法补偿相干光正交频分复用(CO-OFDM)通信系统的非线性损伤是一种具有应用前景的方法。本文针对后向传输(BP)补偿算法计算复杂度高的问题,根据相干光正交频分复用(CO-OFDM)系统中非线性损伤与光功率的关系,通过选取合适的阈值功率点降低BP补偿算法的高计算复杂度。仿真结果表明,提出的方法可以大大降低BP补偿算法的计算复杂度,同时克服了传统算法过补偿的缺点,系统性能也得到提升。在100Gbit/s的CO-OFDM系统中,采用衰减因子为0.2dB/km的零色散光纤,信号传输3 200km(32×100km),光信噪比(OSNR)为16dB时,在选取合适的阈值功率点后,所需的BP补偿步骤数目由传统算法N=61降低为N=13,计算复杂度仅为原来的13/61。此外,采用改进的BP补偿算法补偿之后,系统的Q因子增加了0.204dB。

Improved backward propagation compensation algorithm using threshold power point in CO OFDM systems

In coherent optical orthogonal frequency division multiplexing (CO-OF DM) communication system,backward propagation (BP) compensation algorithm is put forward to compensate the nonlinear damage.However,in engineering application,the BP comp ensation algorithm has high computational complexity.In this paper, an improved algorithm is proposed to reduce the complexity of BP compensation algorithm.An appropriate threshold power point is found according to the relationship between the nonlinearity and the optical power.When the light power transmitted in fiber drops to threshold powe r point,the effect of nonlinearity in fiber can be ignored and the unnecessary BP computation can be o mitted,thus the computational complexity can be largely reduced.We apply the improved meth od to a 100Gbit/s CO-OFDM system based on VPI simulation platform.In the simulation,the zero disp ersion fiber with 0.2dB/km attenuation factor is used,the optical signal noise ratio (OSNR) of system is 16dB and the transmission distance is 3200km.The simulation r esults indicate that the number of BP compensation steps is decreased from 61to 13,and the Q-factor of the system enhanced by 0.204dB.