Time domain equalization for OFDM systems

In this paper, a time domain equalization algorithm is proposed for single-TX multiple-RX OFDM systems over frequency selective fading channels. The algorithm, which cancels most of the intersymbol interference (ISI), utilizes the orthogonality of the IFFT matrix and the second order statistics of the received signals. The signals are then detected, with the aid of only four pilots, from the equalizer output. The number of pilots required in the proposed algorithm is less than that in existing algorithms and channel length estimation is not needed. In addition, the proposed algorithm is applicable to both the case where the channel length is shorter than or equal to the length of cyclic prefix (CP), and the case where the channel length is longer than the length of cyclic prefix which results in inter-block interference (IBI). Simulation results confirm the effectiveness of the proposed algorithm in both cases and indicate that it is more practical as there is no restriction on the channel and CP lengths.