Telecommunications – Transmitter and receiver at separate stations – Distortion – noise – or other interference prevention,...
Reexamination Certificate
2006-01-03
2006-01-03
Eng, George (Department: 2643)
Telecommunications
Transmitter and receiver at separate stations
Distortion, noise, or other interference prevention,...
C455S067160, C375S232000
Reexamination Certificate
active
06983125
ABSTRACT:
Systems and methods according to the present invention are described for adjusting the number of taps in an adaptive equalizer over time as the rate of change of a communications channel varies. The number of taps or “equalizer length” is adjusted based on an estimate of the Doppler frequency between the devices communicating over a channel. The Doppler frequency is reflective of the rate of change of the communications channel. Greater Doppler frequencies indicate a more quickly varying channel, and vice versa. It is therefore desirable to change the equalizer length (by adding or dropping taps) based on a measurement of the Doppler frequency. Equalizer length is increased as the Doppler frequency decreases. Conversely, equalizer length is decreased as the Doppler frequency increases. This enables the equalizer to achieve a better compromise between the competing goals of adaptation speed (less taps) and ISI reduction (more taps).
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Nicol et al. “A Low-Power 128-Tap Digital Adaptive Equalizer for Broadband Modems,” IEEE Journal of Solid State Circuits, IEEE Inc. New York, USA, vol. 32, No. 11, Nov. 1997, pp. 1777-1789.
Fernandez-Corbaton Ivan Jesus
Jayaraman Srikant
Smee John E.
Baker Kent D.
Eng George
Godsey Sandra L.
Qualcomm Incorporated
Wadsworth Philip
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