Training aided frequency domain equalization with maximum-likelihood sequence detection in coherent optical communications systems using FTN signaling

We propose to use training aided frequency domain equalization (FDE) with maximum-likelihood sequence detection (MLSD) in long-haul single carrier optical communications systems using faster than Nyquist (FTN) signaling. Simulation results of the proposed long-haul system are presented, which show that the BER performance of the proposed FDE with truncated MLSD scheme outperforms that of the conventional 2-tap post filter MLSD scheme when the number of taps is greater than 3.