Patent ID: 6990156

Claim:
A frequency offset estimation method for utilizing in a communication system in the environment of an inter-symbol-interference channel with receiving unit, a plurality of data symbols and a receiving sample sequence generated by a plurality of continuously received receiving sample sections having a phase shift and an angular frequency offset, wherein each of said plurality of receiving sample sections is corresponding to one of said plurality of data symbols and contains a plurality of samples which are received continuously; the method comprising the steps of: (a) selecting a first and a second selected receiving sample sections from said plurality of receiving sample sections mapping to the same state of the data symbols and each of said two selected receiving sample sections being indicated by a symbol index; each symbol index being one of a plurality of continuous symbol indices integers corresponding respectively to continuous received receiving sample sections of said received sample sequence; and obtaining a symbol index difference by a difference of respective symbol indexes of said two selective receiving sample sections; (b) complex-multiplying two selective receiving samples of the two selected receiving sample sections, respectively, wherein one of said two selective receiving samples is taken complex conjugate before said complex multiplication, thereby, generating a multiplied value; and (c) repeating said steps (a), (b) for different samples of said two selected receiving sample sections, and for different samples of another different two selected receiving sample sections, respectively, of said plurality of said receiving sample sequence, thereby, generating a plurality of multiplied values; and a plurality of symbol index differences, respectively. (d) obtaining a plurality of generic terms generated from said plurality of multiplied values; (e) generating a plurality of phase angle values of said plurality of generic terms; and dividing said plurality of phase angle values by said plurality of symbol index differences, respectively thereby, generating a plurality of frequency offset estimations; (f) weighting-averaging said plurality of frequency offset estimations by corresponding weighting factors to generate an average frequency offset estimation.