Method of and an apparatus for training tap coefficients of an adaptive equalizer

Abstract

For training tap coefficients of an adaptive equalizer of L taps to be used for equalizing an impulse response of a transmission channel (,) to be shorter than v taps, stably and speedily, a training circuit comprises: a transmitter (,) for transmitting a transmission signal (x(D)) produced by converting a frequency-domain transmission vector (X) encoded with a PRBS into a time-domain; a target-impulse-response update means (,) for producing an updated target impulse response (B,) making use of frequency-domain division method referring to windowed tap coefficients (w,(D)), a reception signal (y(D)), and a training vector (X) encoded with a replica of the PRBS; a target-impulse-response windowing means (,) for outputting a windowed target impulse response (B,) together wit a normalization coefficient (S) by windowing and normalizing the updated target impulse response (B,) within L taps in a time-domain; a tap-coefficient update means (,) for updating the windowed tap coefficients (w,(D)) making use of a frequency-domain LMS method referring to the normalization coefficient (S), the windowed target impulse response (B,), the training vector (X′) and the reception signal (y(D)); and a tap-coefficient windowing means (,) for windowing the updated tap coefficients into v taps. By updating the windowed tap coefficients (w,(D)) repeatedly until a certain convergence condition is attained, the windowed tap coefficients (w,(D)) are outputted as the tap coefficients of the adaptive equalizer.