Doppler spread estimation in mobile communication systems

A new technique based on the auto-correlation function is described for the estimation of the Doppler spread in mobile communication systems. We first propose to divide a uncertainty region of Doppler spread into multiple frequency bins. Based on the given multiple bins the correlator compares the estimated value at a certain time index to the theoretical exact value and then decides which bin the Doppler spread is estimated in. The certain time index can be optimized to give the largest decision region among multiple bins. We derive the optimum time index algorithm to give the largest decision region for each bin based on Rayleigh fading channel. We also apply the same Doppler spread estimator to the Rician case with the slight transformation of the received signal. We show that the proposed technique is not affected significantly by the Rician factor and the SNR degradation with the reasonable number of samples for estimation which is not the case of other estimators given in the literature.