Adjusting dft coefficients to compensate for frequency offset during a sounding sequence used for fractional time determination

Abstract

A receiver includes a first discrete Fourier transform (DFT) block to perform a first single tone DFT on a positive tone associated with a sounding sequence. A second DFT block performs a second single tone DFT on a negative tone associated with the sounding sequence. A DFT coefficient generation block generates first DFT coefficients based on a nominal frequency of the positive tone and an estimated frequency offset between a transmitter frequency and a receiver frequency. The DFT coefficient generation block generates second DFT coefficients based on a nominal frequency of the negative tone and the estimated frequency offset. Multipliers in the DFT blocks multiply I and Q values of the sounding sequence with the coefficients. Accumulators in the DFT blocks accumulate multiplier outputs. An arctan function receives averaged accumulated values from the first and second DFT blocks and supplies first and second phase values used to calculate fractional timing.