Method and apparatus for channel estimation tolerant to timing errors

摘要

Channel estimation is essential in a receiver for many communication systems. In OFDM systems the channel estimation is often performed in frequency domain. Typically an FFT is used to convert a time domain signal into frequency domain signal. The sample position at which the first sample for the FFT is selected depends on the estimated timing position of the OFDM symbol boundary. Any error in the timing position estimate for the OFDM symbol boundary causes linear phase distortion in frequency domain. The linear phase distortion in frequency domain degrades the quality of channel estimation which may be performed in frequency domain. A method and apparatus are disclosed that estimate the FFT window position errors and compensate for the FFT window position error for improved channel estimation.

主权项

1. A method for channel estimation in a wireless communication system, the method comprising:
controlling, by a processing device, for each of a plurality of window positions for each of at least one orthogonal frequency division multiplexing (OFDM) symbol:
performing a Fast Fourier Transform (FFT) at a given window position of a given OFDM symbol;determining a channel estimate for reference symbol (RS) reference elements (REs) of the given OFDM symbol for the given window position, based on a predetermined modulation sequence; anddetermining an average phase difference θ between two adjacent RS REs of the RS REs for the channel estimate for the given window position, by computing an angle of average correlation between the two adjacent RS REs over an entire frequency domain of the given OFDM symbol; and controlling, by the processing device, determining, as an optimum window position for the channel estimation, the window position of the plurality of window positions for the given OFDM symbol for which an absolute value of the average phase difference is smallest.