An adaptive lattice decision feedback equalizer for digital cellular radio

Abstract

A study of an adaptive decision feedback equalizer (DFE) based on a lattice structure, for application in the US digital cellular radio telephone system, is conducted. The scheme uses a least-squares algorithm that is capable of tracking rapid channel variations. The equalizer exploits the order-recursive nature of the lattice structure to adaptively vary the number of taps, thereby achieving a relatively uniform bit error rate (BER) performance over a wide range of delay spreads. Simulation results illustrate the equalizer's sensitivity to delay spread variation, Doppler shift, and sample timing jitter. Comparisons are made with the performance of a fractionally spaced DFE that uses a complex fast Kalman algorithm. Issues of complexity and finite precision implementation are addressed.<>