An improved channel estimation scheme for OFDM systems by tracking the subspace

Channel parameters in OFDM systems over fading channels are generally obtained by transmitting pilot symbols in given positions of the time-frequency grid. The pilot-based method usually involves the LS estimation step on the pilot subcarriers and the interpolation step over the entire time-frequency grid. Increasing the accuracy of the pilot estimation will accordingly increase the precision in the interpolation step. This can be achieved by subspace tracking method. We propose in this paper an improved subspace-tracking algorithm by the Givens plane rotation based delay-subspace tracking and the RLS filtering based amplitude tracking. Performed on a parameterized model of the channel, simulations prove that our channel estimation is more robust and accurate while the complexity of the algorithm is low.