An improved subspace channel estimation for MIMO-OFDM systems

In this paper, the convergence-enhanced subspace channel estimation technique is investigated for MIMO-OFDM systems. The perturbation of noise subspace is inversely proportional to the number of OFDM symbols. Using the block circular property of the channel matrix, we propose the cyclic repetition method (CRM) to generate a group of equivalent signals for each OFDM symbol. The subspace channel estimation can perform very well within a few OFDM symbols using these equivalent symbols for both the CP-OFDM and ZP-OFDM systems. Computer simulations demonstrate the proposed CRM-based channel estimation achieves a lower MSE than the compared ones.