Interference suppression using repeated reduced rank adaptive filtering in fractional Fourier transform (FrFT) domains

A signal-of-interest (SOI) may be separated from interference and/or noise using repeated reduced rank minimum mean-square error Fractional Fourier Transform (MMSE-FrFT) filtering and a low rank adaptive multistage Wiener filter (MWF). A number of stages in the MWF, L, may be chosen such that at the Lth stage, the MSE between the SOI estimate and the true SOI is less than or equal to an error threshold ϵ (e.g., ϵ=0.001). By combining these filtering techniques, significant improvement in reducing the mean-square error (MSE) may be realized over single stage MMSE-FrFT, repeated MMSE-FrFT, and MMSE-FFT algorithmsindeed, by an order of magnitude or more.