OFDMA, Orthogonal Frequency Division Multiple Access is a broad band communication method. Here channel estimation is more crucial. Based on the FFT size used for OFDM transmission method that many number of channel co-efficients are to be estimated and received signals are to be equalized using this co-efficients. Various methods trying to improve the performance and fastness are proposed. As part of master thesis various methods have be studied and evaluated using the WiMAX 802.16 system.