Patent ID: 8509208

Claim:
A method for frequency error estimation, comprising: extracting a pilot tone in a frequency domain for a first user from a first antenna; performing Inverse Discrete Fourier Transform to translate the frequency domain of the pilot tone into a first time domain sequence for the first antenna; multiplying the first time domain sequence with a conjugate of a local replica to obtain a resultant sequence and modulated sequences; projecting the resultant sequence and modulated sequences in an upper half circle and a lower half circle; computing a magnitude square of a vector sum for the upper half circle and the lower half circle to estimate a frequency error correction; and correcting a frequency error by multiplying the first time domain sequence with a rotating phasor, wherein the method further comprises: extracting a second pilot tone in a frequency domain for the first user from a second antenna; performing Inverse Discrete Fourier Transform to translate the frequency domain of the second pilot tone into a second time domain sequence for the second antenna; identifying multi-path components from each of the first and second time domain sequences extracted from each antenna; multiplying each of the multi-path components by their respective time shifted local replica conjugates with an absolute shift specific to the first user to obtain resultant sequences; modifying the absolute time shift of the local replica of the pilot sequence to extract a frequency error of different co-channel users; projecting each of the resultant sequences in an upper half circle and a lower half circle; computing a magnitude square of a vector sum for the upper half circle and the lower half circle in order to estimate a frequency error correction; combining the frequency errors corrections from each of the multi-path components to achieve a combined frequency error correction per antenna; combining the resultant frequency error of each antenna to provide an overall frequency error estimation; and correcting a frequency error by multiplying the time domain sequences with a rotating phasor generated by a Numerically Controlled Oscillator driven by the overall frequency error estimation.