Adaptive prediction iterative channel estimation for OFDM signal reception in a frequency selective fading channel

摘要

An adaptive prediction iterative channel estimation is proposed for the OFDM signal reception in a frequency selective fading channel. Adaptive prediction filtering is incorporated into iterative channel estimation process and the filter tap coefficients are adaptively updated according to changes in the propagation environment. The first stage applies the channel estimation using first order interpolation and extrapolation of frequency-multiplexed pilot subcarriers. The succeeding iteration stages use decision feedback, reverse modulation and the adaptive prediction filter for channel re-estimation. For tap adaptation, the normalized least mean square (NLMS) algorithm is applied that uses the noisy instantaneous channel gain obtained by reverse modulation as the reference signal. The bit error rate (BER) performance in a frequency selective Rayleigh fading channel is evaluated by computer simulation. It is found that iterative channel estimation can reduce the number of pilot subcarriers to achieve the same BER and the adaptive prediction iterative channel estimation provides better BER performance than the channel estimation using fixed-tap filter irrespective of the values of delay spread, fading rate and received E{sub}b/N{sub}0.