![](https://cos-cdn.shuashuati.com/pipixue-web/2020-1231-2005-12/ti_inject-812ce.png)
In order to maintain the reach of a typical 100G WAN transport system(~1500km), several system improvements have to be made to recover the lost (93),including the use of low-loss low-nonlinearity(94),Raman amplification,and stronger error correction.