| 摘要 |
A method of centring a channel impulse response (CIR) of a received Orthogonal Frequency Division Multiplexed (OFDM) signal is disclosed, which allows determination of whether spikes in the CIR relate to echoes of a main signal which precede or succeed the main signal, for correct equalization (fig.14, not shown). A Fast Fourier Transform (FFT) of a received pilot-dense symbol (e.g. the P2 preamble symbol) is generated for a particular FFT window, and for each of a plurality of phase rotations of the FFT, a frequency response estimate is generated, the received pilot-dense symbol is equalized based on the frequency response, an amount of noise on sub-carriers in the pilot symbol is measured, and the rotation producing the lowest noise forms the basis for selecting the positions of the paths in the CIR. |
