Groupwise recursive channel estimation for space-frequency block coded OFDM systems in doubly selective fading channels

In this paper, we propose two computationally efficient groupwise recursive channel estimation algorithms for channel encoded SFBC-OFDM systems in doubly (i.e., frequency and time) selective fading channels. The first of these algorithms is based on the recursive least squares (RLS) principle whereas the second one employs the minimum mean square error (MMSE) criterion. To reduce the computational complexity associated with the groupwise recursive channel estimation schemes, we propose an inverse QR decomposition (IQR) algorithm based on scaled Givens rotations. The performance of the proposed algorithms is evaluated via simulations and compared to the case with perfect channel state information (CSI) knowledge at the receiver. The simulations show that the proposed algorithms perform reasonably close to the perfect CSI case under various channel conditions.