基于WDM-PON架构的5G前传系统中的FWM效应

为了应对快速增长的带宽需求，解决非线性效应限制波分复用无源光网络（wavelength-division multiplexing passive optical network，WDM-PON）系统的传输距离和信道容量，尤其是四波混频（four-wave mixing，FWM）效应的问题。通过实验与仿真研究了25 Gb · s^-1 · λ^-1非归零码（non-return-to-zero，NRZ）信号经过25 km标准单模光纤（standard single-mode fiber，SSMF）传输时，FWM效应对系统所产生的影响。仿真结果表明，在信道间隔为200 GHz的12个波长传输系统中，除了第一个和最后一个信道之外，其他信道误码率（bit error rate，BER）都不能达到前向纠错码（forward error correction，FEC）的门限1.0 × 10^-3。因此，在制定5G前传系统波长分布和信道间隔时，应充分考虑FWM串扰。

FWM Effect in 5G Fronthaul Transmission System Based on WDM-PON Architecture

Wavelength-division multiplexing passive optical network (WDM-PON) is considered as a mainstream solution for 5G fronthaul transmission system to cope with the rapidly increasing demand of bandwidth. However, nonlinearity effects, especially the fourwave mixing (FWM) effect in WDM-PON systems will impair system performances in the transmission distance and channel capacity. In this paper, the influence of FWM effect on multi-wavelength system with 25 Gb·s^-1 ·λ^-1 non-return-to-zero (NRZ) signal over 25 km standard single-mode fiber (SSMF) transmission is explored by experiment and simulation. Study results show that in a 200 GHz spaced 12-channel system, the bit error rate (BER) of all channels, except for the first and last channels, cannot reach the threshold 1.0× 10^-3 of forward error correction (FEC). This implies that FWM crosstalk should be given full consideration while making wavelength plans for 5G fronthaul system, including the wavelength distribution and channel spacing selection.