Interference suppression using repeated reduced rank adaptive filtering in fractional fourier transform (frft) domains
AssigneeThe Aerospace Corporation
InventorSeema Sud
Life of this patent
Estimating the term…
Abstract
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 algorithms—indeed, by an order of magnitude or more.
Claims31
A computer-implemented method for performing reduced rank filtering of a received signal, comprising:
- computing, by a computing system, minimum mean-square error (MMSE) filter coefficients over a rotational parameter for a current optimum filter to be applied to the received signal;
- computing, by the computing system, a best rotational parameter value for the current optimum filter and a current smallest MMSE;
- updating the received signal, by the computing system, using the current smallest MMSE;
- and
- when the current smallest MMSE is not less than or equal to an error threshold, repeating, by the computing system, the computation of the MMSE filter coefficients, the computation of the best rotational parameter value and the current smallest MMSE, and the updating of the received signal using the current smallest MMSE until the current smallest MMSE is less than or equal to the error threshold.
A computer program configured to perform reduced rank filtering of a received signal embodied on a non-transitory computer-readable medium, the program configured to cause at least one processor to:
- (1) compute minimum mean-square error (MMSE) filter coefficients over all values of a rotational parameter for a current optimum filter to be applied to the received signal;
- (2) compute a best value of the rotational parameter and compute a current smallest MMSE;
- (3) update the received signal using the current smallest received signal;
- and
- (4) while the current smallest MMSE is greater than an error threshold, repeat steps (1)-(3) until the current smallest MMSE is less than or equal to the error threshold, wherein
- when the error threshold is reached or exceeded, L sets of rotational parameter values and filter weights are provided.
A computing system, comprising:
- memory storing computer program instructions;
- and
- at least one processor configured to execute the computer program instructions, wherein the instructions, together with the at least one processor, are configured to cause the computing system to:
- apply reduced rank filtering to a received signal for at least one stage L, obtaining a current smallest MMSE at each stage, wherein
- when an error threshold is reached or exceeded, or convergence is achieved, L sets of rotational parameter values and filter weights are provided.
Dependencies are inferred from the claim text.