Patent ID: 7912137

Claim:
A method of correcting frequency offset in Orthogonal Frequency Division Multiple Access (OFDMA) signals, said method comprising: receiving an incoming OFDMA signal at an OFDMA device; computing an estimated frequency offset based on said incoming OFDMA signal at said OFDMA device, wherein said computing said estimated frequency offset includes computing an estimated phase difference between signal values in different slots of a preamble of said incoming OFDMA signal and deriving said estimated frequency offset using said estimated phase difference in a phase difference equation, said phase difference equation defining a relationship between said estimated phase difference and said estimated frequency offset; producing a frequency offset-compensated mixer signal by synthesis of a reference clock signal and said estimated frequency offset at said OFDMA device; mixing said incoming OFDMA signal and said frequency offset-compensated mixer signal to produce a down-converted signal at said OFDMA device; converting said down-converted signal into a digital down-converted signal using said reference clock signal for sampling, said digital down-converted signal including sampling errors due to said reference clock signal at said OFDMA device; digitally correcting said sampling errors in said digital down-converted signal using said estimated frequency offset at said OFDMA device; and computing an estimated symbol timing offset using said estimated phase difference.