Subspace-based semi-blind channel estimation for STC-OFDM

A subspace-based blind method is proposed for estimating the channel responses of a STC-OFDM system with two transmit antennas and one receive antenna. It gives estimations to the two channel responses subject to two ambiguity parameters. The method is valid whether the two channel transfer functions are coprime or not and does not require precise channel order information (only an upper bound for the orders is required). Furthermore, a method is presented to resolve the ambiguities by using two or more pilot symbols. Simulations show that the methods are effective and robust.