US Patent 7742391 Apparatus and method for estimating frequency offset

In a frequency offset estimating device of a subscriber station of a communication system in which a plurality of sectors are allocated to a cell, the frequency offset estimating device extracts a preamble sequence from a downlink frame signal. The frequency offset estimating device estimates a phase offset of a sector to which the subscriber station belongs among the sectors by using the preamble sequence, and calculates the autocorrelation value for the respective signals of the preamble sequence. The frequency offset estimating device compensates the autocorrelation value by using the phase offset, and estimates a frequency offset from the sum of the phase offset compensated autocorrelation values.