Patent ID: 7782985

Claim:
A method for compensating in a received wireless communication signal frequency offsets caused by imperfect synchronization between a transmit clock used to modulate a burst with a constellation of orthogonal frequency subcarriers and a receive clock used to recover individual subcarriers from the burst, at least some of said subcarriers being modulated with data bearing symbols, the method comprising: sampling bursts of received signals at regular intervals; said sampling using said receive clock; performing a time domain correlation between two successively sampled copies of a same distinctive pattern of symbols, said two copies being offset in time within a same said burst by a known integer number of symbols, to thereby calculate a measured coarse offset between an expected spacing and a measured spacing; performing a frequency domain correlation on a known frequency pilot signal within said burst responsive to said coarse offset to thereby calculate fine frequency offset data for the received pilot signal at various points within said burst; and using said calculated fine frequency offset data from the pilot signal, calculating corresponding frequency offsets for other subcarriers frequencies in a constellation containing said burst.