In OFDM based mobile communication systems, channel variation during one symbol period introduces intercarrier interference (ICI). Conventional pilot-aided equalization mitigates the ICI at the price of band inefficiency. On the other hand, the blind or semi-blind equalization method, which utilizes the known statistic properties of the transmitted data, will raise system complexity. In this letter, without bandwidth-consuming pilots, a novel channel estimation and tracking method based on an iterative equalization technique (IET) is proposed. The proposed approach successfully achieves a good compromise between bandwidth efficiency and system complexity, and its validity is demonstrated by numerical simulations, especially for fast fading channel.

In mobile OFDM systems, sub-carriers orthogonality will be broken due to Doppler shift, and this results in inter-carrier interference (ICI). Many methods have been proposed to compensate for this, however, these methods won't be suitable for fast fading caused by high mobile speed. In this letter, we propose a novel sampling theorem based pilot symbol-aided technique which can not only estimate the channel fading envelope (CFE) accurately under high relative Doppler frequency (RDF) but also achieve lower BER than conventional methods. The validity of the proposed method is demonstrated by computer simulations.