Separation of the frequency drift from the Doppler shift in multi-carrier systems

摘要

Individual multipath components of digital data symbols sent from a transmitter on at least two carrier frequencies generated from a common clock signal, are received (401) with individual delays and processed by a receiver unit having at least two fingers. Successive channel estimates are determined (402) from received symbols for each finger and each carrier, and an estimated frequency error is determined (404) for each finger and each carrier. A linear equation system is constructed (405), in which each determined frequency error is expressed as a function of a first variable indicative of frequency drift and a second variable indicative of frequency error caused by Doppler effect. The equation system is solved (406) to provide a solution with estimates of the first and second variables for each finger, and an estimated frequency drift is determined (407) from the solution and utilized (408) as feedback signal for adjusting receiver clock frequency.