Decision-directed fractionally spaced equalizer control using time-domain interpolation

Chromatic dispersion and nonlinear phase noise compensation based on KLMS method

“…A fractionally spaced equalizer (FSE) in the time domain can compensate sampling time errors [10], by using an oversampling rate of two for CD compensation [5,8,11]. Linear mean square (LMS) algorithm which allows the recovery of signal in blind mode, works in the time domain [10]. In [3], the authors have considered a one-tap normalized least mean square (NLMS) technique in equalization enhanced phase noise (EEPN) for carrier phase estimation.…”

“…CD compensation is also performed in time domain using tap delay sampling [7,8] and maximum likelihood sequence estimation (MLSE) [9] based on the gradient decent algorithm which can be implemented by decision feedback equalizer (DFE) with less computational complexity in comparison with frequency domain methods. A fractionally spaced equalizer (FSE) in the time domain can compensate sampling time errors [10], by using an oversampling rate of two for CD compensation [5,8,11]. Linear mean square (LMS) algorithm which allows the recovery of signal in blind mode, works in the time domain [10].…”

Design of a power-scalable digital least-means-square adaptive filter

“…Thus, the equalizer transfer function is not uniquely determined and tap-weights can drift and take very large values. Various solutions have been suggested, such as Tap-leakage [10] and others [37,19,18].…”