Subspace-Based Blind Channel Estimation for OFDM by Exploiting Cyclic Prefix

A new subspace-based blind channel estimation (SBCE) approach for cyclically prefixed orthogonal frequency-division multiplexing (CP-OFDM) is proposed to provide enhanced estimation performance. Based on the redundant structure that CP reproduces the tail part of the useful signal vector, a predetermined null subspace corresponding to the transmitted CP-OFDM signal vector subspace is identified and enables the proposed estimator to extract the channel impluse response by projecting the received signal onto the predetermined null subspace. While requiring less implementation complexity, the proposed channel estimator is shown to outperform conventional SBCE approaches in mean-square error performance when the number of received blocks and the received signal-to-noise power ratio are not large.