Superimposed composite channel filter
First Claim
1. A method for generating digital filter coefficients utilized in a wireless environment, the method comprising:
- appending zeros to an M-sample impulse response in time domain to create a zero padded impulse response of NFFT in length, wherein M and NFFT are positive integers;
Fourier transforming the NFFT length zero-padded impulse response;
performing a circular shift of the Fourier-transformed zero-padded impulse response; and
adding in frequency domain a set of circularly-shifted, Fourier-transformed zero-padded impulse responses to generate a set of composite digital filter coefficients.
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Abstract
Methods and systems are provided to generate digital coefficients for a filter. The generation of coefficients relies on a Fourier transformation of an impulse response in time domain that is zero padded, e.g., zeros are appended to an array corresponding to a sampled input signal of length M. A unit prototypical filter is generated through a frequency domain response of length NFFT=NS+M−1, wherein NS is a sampling length of the incoming signal. The unit prototypical filter is then circularly shifted in order to generate a band pass filter centered at a desired frequency. Circularly shifted filters are point-to-point added to generate a set of composite digital coefficients to filter the incoming signal. The reference frequencies for the composite filter are extracted from a message received from one or more base stations associated with one or more service providers. The composite filter typically operates on a frequency repeater.
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Citations
26 Claims
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1. A method for generating digital filter coefficients utilized in a wireless environment, the method comprising:
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appending zeros to an M-sample impulse response in time domain to create a zero padded impulse response of NFFT in length, wherein M and NFFT are positive integers; Fourier transforming the NFFT length zero-padded impulse response;
performing a circular shift of the Fourier-transformed zero-padded impulse response; andadding in frequency domain a set of circularly-shifted, Fourier-transformed zero-padded impulse responses to generate a set of composite digital filter coefficients. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17)
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18. A wireless device comprising:
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a processor configured to generate an M sample impulse response in time domain, to perform an array padding operation, wherein M is a positive integer;
to compute a Fourier transformation of at least one of the M-bin impulse response or an NFFT-bin frequency sequence, wherein NFFT is a positive integer;
perform a circular shift of an NFFT-bin Fourier transformed impulse response;
to add a set of Fourier transformed zero-padded impulse responses;
to generate a composite mask filter utilizing the added Fourier-transformed impulse responses; anda memory coupled to the processor. - View Dependent Claims (19, 20, 21, 22, 23, 24)
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25. An apparatus that operates in a wireless environment, the apparatus comprising:
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means for zero padding an M-bin impulse response in time domain to an NFFT-bin length, wherein M and NFFT are positive integers; means for Fourier transforming the NFFT-bin zero-padded impulse response; performing a circular shift of the Fourier-transformed zero-padded impulse response; means for adding in frequency domain a set of circularly-shifted, Fourier-transformed zero-padded impulse responses to generate a filter mask; means for conveying the generated filter mask to a frequency bin multiplier block; and means for applying the generated filter mask to a set of frequency domain bins of a block of signal to be repeated.
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26. A computer-readable storage medium, volatile or non-volatile, encoded with a computer program, the computer program including:
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code for causing a computer to pad an M-bin impulse response in time domain to an NFFT-bin length, wherein M and NFFT are positive integers; code for causing a computer to Fourier transform the NFFT-bin zero-padded impulse response; code for causing a computer to perform a circular shift of the Fourier-transformed zero-padded impulse response; and code for causing a computer to add in frequency domain a set of circularly-shifted, Fourier-transformed zero-padded impulse responses to generate a filter mask; and code for causing a computer to apply the generated filter mask to a set of frequency domain bins of a block of signal to be repeated.
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Specification