Nonlinear Filtration in the Problem of Joint Estimation of Channel Factors and OFDM Signal Distortion Arising in Direct Conversion Receiver

A combined algorithm for joint estimation the distortions of the OFDM signal and channel factors is proposed in the article. The algorithm is based on two procedures: 1) estimating the generalized channel factors using a polynomial spline approximation, the least squares method and finding the signal distortion estimates for them, 2) a nonlinear filtering algorithm to refine the parameters values such as DC components and frequency offset. The algorithm operates on two reference OFDM symbols under conditions of a priori uncertainty regarding phase noise and observation noise, and also allows to increase noise immunity and reduce computational complexity, as compared with the case of using only procedure 1).