METHOD OF ESTIMATING FREQUENCY SHIFT FOR COMMUNICATION SYSTEMS USING OFDM SIGNALS Russian patent published in 2016 - IPC H04B1/68 

FIELD: radio engineering and communications.

SUBSTANCE: invention relates to radio engineering, particularly to methods of estimating frequency shift, and can be used in wireless telecommunication systems using OFDM signals, as well as in control and measuring equipment. For this purpose, further introduced: operation eliminating frequency shift in digital form for each OFDM symbol contained in frame, enhanced operation frequency shift estimation of N symbols following pilot symbol, provided that specified evaluation can participate only those OFDM symbols, which can be correctly demodulated, after rough estimating frequency shift, operation assessment of transfer function of pilot subcarriers, equalization, restore operation of spectrum of each OFDM symbol to initial kind, given in transmitter at minimum distance between obtained count spectrum and appropriate, specified standard, which operates communication system, calculating ratio of the spectrum of one of OFDM symbols, participating in specified estimation of frequency shift, to each of OFDM symbols, participating in specified estimation of frequency shift, multiplication of spectrum of each received OFDM symbol, participating in specified frequency shift estimation on calculated ratio, calculation of phase difference between adjacent OFDM symbols included in specified estimation of frequency shift, averaging of calculated values of phase difference, calculation of specified frequency shift estimation as ratio of averaged evaluation of difference of phases at 2π and duration of one OFDM symbol, calculating resultant frequency shift estimation as the sum of rough and precise evaluation.

EFFECT: technical result consists in improvement of accuracy of estimating carrier frequency shift at low signal/noise ratio and frequency-selective fading, using one pilot OFDM symbol, consisting of 2 identical repeating parts.

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