Orthogonal Frequency Division Multiplexing (OFDM) is considered an effective technique in high speed digital transmission because of its spectral efficiency, robustness in different multipath propagation, and capability to fight with inter-symbol interference (ISI).  On the other hand, as the speed of the mobile terminal increases, the channel becomes time-selective  and  variations of the channel within a multicarrier symbol lead to a loss of subchannel orthogonality, resulting in interchannel interference (ICI).  Conventional channel estimators assume a time-invariant model for the channel during one OFDM symbol and do not take ICI into account caused by the high mobility. In order to get optimum performance from OFDM system over fast fadinf channels, very efficient channel estimators are required. Pilot-aided channel estimation for OFDM systems mostly need an interpolation method to estimate the channel response on non-pilot subcarriers. Selection of interpolation method effects the performance and complexity of the system. In this paper, we propose a two-dimensional (2D) pilot-symbol assisted channel estimation for wireless OFDM systems by using low-pass interpolation which is applied in both time and frequency domains. The proposed method has the advantage of minimising the system complexity and processing delay, providing a good approximation to the real mobile channel. 

PILOT-BASED 2D CHANNEL ESTIMATION FOR OFDM OVER FAST FADING CHANNELS