Patent ID: 8774034

Claim:
A method for estimating and correcting a frequency offset in an orthogonal frequency division multiplexing system, comprising: obtaining a pilot frequency domain channel estimation value of a target user and smoothing the channel estimation value in frequency domain; wherein, the step of obtaining the pilot frequency domain channel estimation value of the target user and smoothing the channel estimation value in frequency domain comprises: obtaining channel estimation values corresponding to two pilots according to a local frequency domain pilot code and a frequency domain receiving sequence of the two pilots received by the target user; and dividing the channel estimation value corresponding to each pilot of the target user into a plurality of sections, and performing frequency domain smoothing in each section; obtaining a link quality state of a receiver: performing frequency offset estimation and frequency offset compensation by a history smoothing algorithm, performing a frequency domain demodulation for the data for which the frequency offset compensation has been performed and outputting one link quality state parameter, according to a history frequency offset value and the pilot frequency domain channel estimation value of the target user when the link quality state satisfies a startup threshold condition, wherein the history frequency offset value is a frequency offset value from a last frequency offset estimation output; performing the frequency offset estimation and frequency offset compensation by a multi-branch attempt algorithm, performing the frequency domain demodulation for the data for which the frequency offset compensation has been performed and selecting to output one link quality state parameter, according to the pilot frequency domain channel estimation value of the target user when the link quality state does not satisfy the startup threshold condition; and updating the link quality state of the receiver according to the link quality state parameter, determining the output value of this frequency offset estimation, and outputting a history frequency offset value required by next frequency offset estimation according to the determined output value of this frequency offset estimation; wherein the history smoothing algorithm comprises: calculating a frequency offset estimation value of the target user by using the history frequency offset value and the pilot frequency domain channel estimation value of the target user, and performing the frequency offset compensation according to the calculated frequency offset estimation value of the target user; and wherein the multi-branch attempt algorithm comprises: calculating the frequency offset estimation value of the target user by using the pilot frequency domain channel estimation value of the target user and each compensation initial value, and performing the frequency offset compensation according to the calculated frequency offset estimation value of the target user.