Patent ID: 8675747
Filing Date: 2014-03-18
Classification: H04L

Abstract:
1. A channel estimating apparatus, applied to a data communication system using an Orthogonal Frequency-Division Multiplexing (OFDM) modulation, the data communication system receiving data in the form of a plurality of OFDM symbols, the channel estimating apparatus comprising: an Inverse Fast Fourier Transform (IFFT) unit, that performs IFFT on each of a plurality of preliminary estimated frequency-domain channel responses corresponding to the OFDM symbols received from a transmitter, with a second number of sampling points, to generate a plurality of first time-domain channel impulse responses corresponding to the OFDM symbols, each of the preliminary estimated frequency-domain channel responses having a first number of response values, the first number being greater than the second number such that calculation complexity and size of the IFFT unit are reduced; a filter unit, that filters by a time-domain window the first time-domain channel impulse responses to generate a plurality of second time-domain channel impulse responses corresponding to the OFDM symbols; a smoothing unit, that smoothes the second time-domain channel impulse responses to generate a plurality of smoothed time-domain channel impulse responses that are corresponding to the OFDM symbols and time variance of a channel; and a Fast Fourier Transform (FFT) unit, that performs FFT with the first number of sampling points on each smoothed time-domain channel impulse response to generate a plurality of frequency-domain channel impulse responses corresponding to the OFDM symbols, wherein the IFFT unit comprises a multiplier that performs a phase shift on the preliminary estimated frequency-domain channel responses corresponding to the OFDM symbols to generate the first time-domain channel impulse responses.