Orthogonal frequency-division multiplexing (OFDM) is an effective technique to cope with frequency-selective fading channels in broadband wireless communications. The performance of this technique depends mainly on the accuracy in channel frequency response (CFR) estimation. Most high performance channel estimation schemes exploit the correlation of the CFRs of subchannels which rely on the knowledge of channel statistics. There are also some model-based methods which are relatively simple in implementation and less dependent of the CFR correlation. However, the proposed model-based methods, applicable to OFDM systems with periodic training blocks, are less spectrally efficient comparing to those with scattered pilots. In this work, we consider the scenario of the OFDM systems with scattered pilots, the model-based method is modified and incorporated with a decision-directed feedback procedure. The proposed scheme achieves improved performance comparing to the traditional model-based methods using scattered pilots. A uncoded BER performance less 0.5 dB away from the ideal CFR performance is demonstrated when DVB-T is considered as the example OFDM system.