The Faster-Than-Nyquist(FTN)signaling-based scheme is a high spectral efficiency transmission scheme for largecapacity optical communication systems.This paper reviews the latest FTN signaling-based transmission schemes in the world,such as cascaded multi-modulus blind equalization FTN,digital FTN and Soft Output FTN(SOFTN).The cascaded multimodulus blind equalization FTN can effectively suppress noise and inter-channel crosstalk,the digital FTN can effectively simplify the system structure and the SOFTN ha...