Blind Channel Estimation for SIMO OFDM Systems without Cyclic Prefix

In sacrificing the bandwidth efficiency, the insertion of cyclic prefix (CP) is used in OFDM system to combat ISI and allow for a simple one-tap equalization scheme. In this paper, the OFDM system without CP equipped with multiple antennas at the receiver is studied. Without ignoring the ISI components, the subspace channel estimation and MMSE equalizers are proposed. Besides, due to the block Toeplitz structure of channel matrix, the block matrix scheme is developed to increase several times of sample vectors, which results in better performance of subspace channel estimation in a finite sample scenario. The computational complexity of the proposed method increases slightly over the conventional subspace method. Computer simulations are given to verity the effectiveness of the proposed methods