Time tracking loops for a communication system utilizing a cyclic prefix
First Claim
1. A method for communication, comprising:
- deriving a first channel impulse response (CIR) estimate based on early received samples;
deriving a second CIR estimate based on late received samples;
determining a fast Fourier transform (FFT) window position based on the first and second CIR estimates; and
selecting received samples for processing based on the FFT window position.
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Abstract
Techniques for performing time tracking in a communication system utilizing a cyclic prefix are described. In an aspect, a receiver may detect for large timing errors based on early and late received samples obtained with early and late FFT windows, respectively. The receiver may derive first and second channel impulse response (CIR) estimates based on the early and late received samples, respectively, determine an early channel energy based on the first CIR estimate, determine a late channel energy based on the second CIR estimate, compute an update amount based on the early and late channel energies, and update the FFT window position based on the update amount. In another aspect, the receiver may perform time tracking with an inner time tracking loop (TTL) and an outer TTL. The receiver may update the FFT window position in coarse steps with the outer TTL and in fine steps with the inner TTL.
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Citations
20 Claims
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1. A method for communication, comprising:
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deriving a first channel impulse response (CIR) estimate based on early received samples; deriving a second CIR estimate based on late received samples; determining a fast Fourier transform (FFT) window position based on the first and second CIR estimates; and selecting received samples for processing based on the FFT window position. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. An apparatus for communication, comprising:
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means for deriving a first channel impulse response (CIR) estimate based on early received samples; means for deriving a second CIR estimate based on late received samples; means for determining a fast Fourier transform (FFT) window position based on the first and second CIR estimates; and means for selecting received samples for processing based on the FFT window position. - View Dependent Claims (13, 14, 15)
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16. An apparatus for communication, comprising:
at least one processor configured to; derive a first channel impulse response (CIR) estimate based on early received samples; derive a second CIR estimate based on late received samples; determine a fast Fourier transform (FFT) window position based on the first and second CIR estimates; and select received samples for processing based on the FFT window position. - View Dependent Claims (17, 18, 19)
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20. A computer program product, comprising:
a non-transitory computer-readable medium comprising; code for causing at least one computer to derive a first channel impulse response (CIR) estimate based on early received samples; code for causing at least one computer to derive a second CIR estimate based on late received samples; code for causing at least one computer to determine a fast Fourier transform (FFT) window position based on the first and second CIR estimates; and code for causing the at least one computer to select received samples for processing based on the FFT window position.
Specification