A new subspace algorithm for blind channel estimation in broadband space-time block coded communication systems

In this paper a new subspace method for blind estimation of frequency-selective channels is proposed. Specifically, we consider the case of broadband space-time block coded (STBC) transmissions such as STBC-OFDM, space-frequency block coding (SFBC), or time-reversal STBC. The proposed technique is able to exactly recover the channel within a limited number of data blocks, and its computational complexity is linear in the number of subcarriers or data-block size. Furthermore, it is independent of the specific signal constellation, and therefore it can also be applied when the sources have been precoded to exploit the multipath diversity. Finally, the performance of the proposed method is evaluated by means of some numerical examples.