Decision feedback equalization for digital cellular radio

The authors study an adaptive decision feedback equalizer (DFE) for application in the USA digital cellular radio telephone system. A synchronous DFE and a fractionally spaced DFE are adaptive and use a fast recursive least squares algorithm to track rapid channel variations. Simulation results indicating the performance sensitivity to time delay spread, Doppler shift, and timing jitter are presented. A DFE using a complex fast-Kalman adaptation algorithm is presented, and its bit error rate performance evaluated. The fast Kalman equalizer is found to possess good tracking ability and can track channel variations at vehicle speeds of 50 mph (80 km/h). Sensitivity to sample timing jitter can be reduced by using a DFE with fractionally spaced feedforward taps