Blind channel estimation for CP-free OFDM communications systems

In this paper, a subspace method is proposed for blind channel estimation in orthogonal frequency-division multiplexing (OFDM) systems over time-dispersive channel. By removing the cyclic prefix (CP) and training sequence, the proposed method is spectral efficient. By exploiting the block Toeplitz structure of the channel matrix, the proposed method increases the number of the equivalent received vectors which results in high data efficiency. As a result, the proposed algorithm is able to identify the channels using very few received OFDM data blocks which makes it possible candidate for wideband communication scenarios where the channel is time-invariant for only a few OFDM symbols. Computer simulations demonstrate the superior performance of the proposed algorithm over some existing subspace-based methods.