Method for adaptive equalization of differential phase modulated signals

摘要

For adaptive equalization of a differential phase modulated signal transmitted by a transmitter, a receiver (2) determines an estimate of a signal constellation ys(n) in the transmitter before phase integration of the transmitted signal. The receiver (2) determines an error signal e(n) as a difference between the estimate of the signal constellation ys(n) and a phase-differentiated output yd(n) of an equalizer (23) in the receiver (2). Based on the error signal e(n), in the receiver (2), equalizer coefficients (wm) are determined and updated adaptively. The receiver (2) is moved iteratively towards the optimum coefficient setting with regards to the minimum squared error. Preferably, the equalizer (23) is configured as a fractionally-spaced equalizer using a sampling rate higher than 1/T, T being the period of the symbols in the differential phase modulated signal. Advantageously, the equalizer (23) is insensitive to phase offset and small frequency errors.