Adaptive equalization and diversity combining for mobile radio using interpolated channel estimates

The authors demonstrate the feasibility of a digital cellular radio (DCR) system which employs a jointly adaptive decision-feedback equalizer and diversity combiner. In particular, the authors utilize the current estimates of the channel impulse response (CIR) at each diversity branch to compute the receiver parameters periodically. The authors propose a novel block-adaptive strategy which computes the time-varying CIR by interpolating a set of CIR estimates obtained through periodic training. Although incurring some inherent processing delay and throughput reduction, this interpolation strategy has the advantage of immunity to decision errors which would quite likely occur during a deep fade. It is shown that the system performance is limited, in the form of an irreducible bit error rate at high signal-to-noise ratios (SNRs), by the CIR estimation of the rapidly fading channel