1. A receiver for a digital cellular communication system in which a mobile unit and a base station unit are linked, the receiver being included in at least one of the mobile and the base station units and comprising: means for receiving transmitted signals encoded with a preselected trellis or block code; means for demodulating the received signals to generate digital word signals for decoding; means for computing phase error magnitude for each channel symbol in the received signals; means for computing magnitude error for each channel symbol in the received signals; means for estimating mobile unit speed from demodulating data; and means for decoding the digital word signals in accordance with the phase error magnitude and the magnitude error as a function of the mobile unit speed.