A Blind Channel Estimation for 100+ Gb/s Optical IM-DD DMT Over 100-km SMF in 1550 nm

A blind and adaptive decision-feedback channel estimation method is proposed for optical intensity-modulated direct detection discrete multitone transmissions. Due to the channel state variation nature of the fiber, periodic channel estimation update is required. In previous works, periodic preambles are transmitted to acquire and track the channel state information at the receiver. In the proposed method, instead of using periodic preambles, the estimated channel is updated adaptively after decoding a sequence of orthogonal frequency-division multiplexing symbols using least-squares and minimum mean-square error criteria. The simulation results corroborate that the proposed method increases data-rate by 10%, and at the same time provides 0.24-dB Q-factor gains that can be converted into extra 2% data-rate increase, algorithm simplicity, or cost reduction.