Channel-estimation-based adaptive DFE for fading multipath radio channels

Abstract

The performance of an adaptive decision feedback equaliser (DFE) over an HF channel when its taps are derived from an estimate of the sampled channel impulse response is examined. The conventional approach to adaptation is to adjust the equaliser taps directly to minimise a least squares error cost function. It is shown that the channel estimate approach not only yields superior performance, but also involves fewer computations than the conventional square-root-Kalman approach. The problem of channel estimation is mathematically analysed for both the steepest descent and recursive least squares algorithms, and theoretical results are compared with simulation. It is also shown how simple theoretical predictions of the performance of the DFE can be made when using this alternative method of implementation.