Patent ID: 8130848

Claim:
A method for performing a channel estimation for an OFDM-based wireless communication system using sparsely spaced pilot subcarriers, the method comprising: receiving an OFDM-based signal including data and pilot subcarriers; collecting the pilot subcarriers of the OFDM-based signal, including the pilot subcarriers of the OFDM-based signal in an interpolation window, the interpolation window being defined as at least one OFDM-based symbol index in the time domain where same channel estimates will be used and a set of pilot and data subcarrier location indexes in the frequency domain; estimating at least some pilot subcarriers for the interpolation window using some of the pilot subcarriers that are outside of the interpolation window to produce estimated pilot subcarriers of the interpolation window; computing pilot channel estimates at the pilot subcarrier locations in the interpolation window using the pilot subcarriers in the interpolation window and the estimated pilot subcarriers; and interpolating the pilot channel estimates to derive data channel estimates at data subcarrier locations for the data subcarriers in the interpolation window, wherein the estimating includes combining multiple pilot subcarriers outside of the interpolation window to produce one of the estimated pilot subcarriers of the interpolation window, the multiple pilot subcarriers being located at a particular pilot subcarrier location, and wherein the combining includes applying a one-tap FIR filtering across the multiple OFDM-based symbol indexes on the pilot subcarriers of the particular pilot subcarrier location using: {tilde over (y)} pilot,n k ( m )=α y pilot,n k ( m+Δ 1k )+(1−α) y pilot,n k ( m−Δ 2k ), where α is a weighting factor between 0 and 1 that determines any contribution of each pilot subcarrier to be combined, and Δ 1k and Δ 2k are appropriate OFDM symbol offsets where the pilot index n k is located.