Doppler frequency shift estimation for differentially coherent CPM

Urban Propagation Modeling for Wireless Systems

“…Austin and Stüber [6] expand on this technique to show that by using the autocorrelation across multiple symbols, in addition to the autocorrelation between adjacent symbols, as done by [13], the variance of the estimate from the true mean may be reduced, even in a Ricean fading environment,…”

“…Velocity estimators, such as those by [6,13,62], require a precise frequency reference at the receiver to detect small changes in frequency or phase shift that are caused by the mo- Without a precise frequency reference at the receiver, the carrier recovery loop tracks the received carrier frequency which may have been subjected to a frequency shift. In the most general case, the scattering environment is also unknown.…”

“…The contraint (C.5) limits the maximum Doppler shift detectable by this estimator based on the symbol period (T s ) and the constellation size (M ). Furthermore, samples in the time average that are heavily affected by fading should be weighted less in the overall average [13].…”

“…must hold [13]. The contraint (C.5) limits the maximum Doppler shift detectable by this estimator based on the symbol period (T s ) and the constellation size (M ).…”

“…To use the simple, constant weighting suggested by Biglieri [13], the window over which the autocorrelations are taken must consist of symbols that are not affected by fading. To meet this fading constraint, the autocorrelation interval is constrained to one-tenth of the channel coherence time.…”