Abstract: The author proposes that the channel coefficient of the effective arriving path can be estimated with the Rake coherent receiver. By calculating the level cross rate (LCR) of the envelope, the Doppler-shift is estimated. The observation length is then adjusted dynamically with the help of the connection between the Doppler-shift and the optimal observation length, enabling the whole receiver to obtain better performance in variant velocities.

Key words: code division multiple access (CDMA), level crossing rate (LCR), the Rake receiver, Dopplershift