Analysis and Mitigation of Doppler Rate Effect in a Multipath Channel

Establishing robust communications in the presence of Doppler rate is a requirement for several waveforms such as SATCOM and HF. In this paper, we motivate the need to model Doppler rate by analyzing the kinematics of motion in the 2-D plane. We formulate the time-varying, multipath channel output as a composite chirp signal with a convolutive mix. We propose a data-aided method to transform the channel output into a composite signal whose chirp parameters can be estimated by existing techniques. We present a method to decouple chirps from the channel output and estimate channel coefficients. The performance of the channel estimator is characterized in terms of mean-squared-error. The sensitivity of the algorithm to errors in chirp estimates is studied as a function of symbol rate.