METHOD AND SYSTEM FOR COMPENSATION OF A CARRIER FREQUENCY OFFSET IN AN OFDM RECEIVER

摘要

An Orthogonal Frequency Division Multiplexing (OFDM) receiver that employs N second-order phase-lock loops (62-66, 74-78) sharing a common integrator (72) (where N is the number of pilots in the system). The N second order phase-lock loops (62-66), 74-78) track out independent pilot phase rotations to facilitate the constructive averaging of the pilots' phase information. At the same time by sharing a common integrator (72), the OFDM receiver takes advantage of noise averaging over multiple pilots to obtain a cleaner frequency offset estimation. The OFDM receiver may also compensate for FFT window drift by calculating (84) a phase difference between a selected pair of pilots and tracking (86) the rate of change of the calculated phase difference over time. The calculated phase difference is used to control the position of an upstream FFT window after a predetermined phase difference threshold is exceeded. The tracked rate of change is used to continuously adjust the phase of downstream equalizer taps (82).