Pilot-assisted doppler frequency estimation
First Claim
1. A method of estimating the Doppler frequency of an input signal comprising a pilot signal, the method comprising:
- (a) accumulating a plurality of samples from the input signal over a specified time duration to derive a channel tap estimate;
(b) obtaining a sequence of channel tap estimates by repeating step (a) until a specified number of channel tap estimates have been accumulated;
(c) performing a Fourier transform of the sequence of channel tap estimates to obtain a complex sequence of values;
(d) finding an index value for which a power spectral distribution function of the complex sequence of values exceeds a specified threshold; and
(e) obtaining an estimate of the Doppler frequency by dividing the index value found in step (d) by the product of the specified number of channel tap estimates and the specified time duration.
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Accused Products
Abstract
A technique for estimating the Doppler frequency of an input signal comprising a pilot signal. In one embodiment, the technique comprises: (a) accumulating a plurality of samples from the input signal over a specified time duration to derive a channel tap estimate; (b) obtaining a sequence of channel tap estimates by repeating step (a) until a specified number of channel tap estimates have been accumulated; (c) performing a Fourier transform of the sequence of channel tap estimates to obtain a complex sequence of values; (d) finding the smallest index value for which a power spectral distribution function of the complex sequence of values exceeds a specified threshold; and (e) obtaining an estimate of the Doppler frequency by dividing the smallest index value found in step (d) by the product of the specified number of channel tap estimates and the specified time duration.
14 Citations
20 Claims
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1. A method of estimating the Doppler frequency of an input signal comprising a pilot signal, the method comprising:
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(a) accumulating a plurality of samples from the input signal over a specified time duration to derive a channel tap estimate;
(b) obtaining a sequence of channel tap estimates by repeating step (a) until a specified number of channel tap estimates have been accumulated;
(c) performing a Fourier transform of the sequence of channel tap estimates to obtain a complex sequence of values;
(d) finding an index value for which a power spectral distribution function of the complex sequence of values exceeds a specified threshold; and
(e) obtaining an estimate of the Doppler frequency by dividing the index value found in step (d) by the product of the specified number of channel tap estimates and the specified time duration. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. Apparatus for estimating the Doppler frequency of an input signal comprising a pilot signal, the apparatus comprising:
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a signal estimator block adapted to (a) accumulate a plurality of samples from the input signal over a specified time duration to derive a channel tap estimate, and (b) obtain a sequence of channel tap estimates by repeating step (a) until a specified number of channel tap estimates have been accumulated;
a Fourier transform block adapted to perform a Fourier transform of the sequence of channel tap estimates to obtain a complex sequence of values;
a power spectral distribution block adapted to find an index value for which a power spectral distribution function of the complex sequence of values exceeds a specified threshold; and
a Doppler estimation block adapted to obtain an estimate of the Doppler frequency by dividing the index value found by the power spectral distribution block by the product of the specified number of channel tap estimates and the specified time duration. - View Dependent Claims (14, 15, 16, 17, 18, 19)
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20. A machine-readable medium, having encoded thereon program code, wherein, when the program code is executed by a machine, the machine implements a method for estimating the Doppler frequency of an input signal, the method comprising:
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(a) accumulating a plurality of samples from the input signal over a specified time duration to derive a channel tap estimate;
(b) obtaining a sequence of channel tap estimates by repeating step (a) until a specified number of channel tap estimates have been accumulated;
(c) performing a Fourier transform of the sequence of channel tap estimates to obtain a complex sequence of values;
(d) finding an index value for which a power spectral distribution function of the complex sequence of values exceeds a specified threshold; and
(e) obtaining an estimate of the Doppler frequency by dividing the index value found in step (d) by the product of the specified number of channel tap estimates and the specified time duration.
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Specification