Cramér-Rao bound for blind channel estimation in cyclic prefixed MIMO-OFDM systems with few received symbols

In this paper, a Cramér-Rao bound (CRB) for blind channel estimation in cyclic prefixed MIMO-OFDM systems is derived. The derived bound is valid for arbitrary numbers of transmit antennas, received antennas, and received symbols available for blind channel estimation, and serve as a benchmark of performances for several recently reported subspace-based algorithms. Computer simulations are conducted to compare these algorithms with the derived bound. The results show that there are still rooms for improvement for the currently available blind channel estimation algorithms^†.