Dual frequency tracking loop for OFDMA systems
AssigneeQUALCOMM Incorporated
InventorsBrian C. Banister, Shivratna G. Srinivasan, Matthias Brehler, Sunil Kumar Kandukuri Narayana, Raghu N. Challa
Life of this patent
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Abstract
Methods and apparatus for correcting frequency errors between a carrier frequency of a signal received by a wireless device and a reference frequency local to the device. For certain aspects, such a method generally includes receiving a signal in a receiver having an LO producing a reference frequency, a radio frequency (RF) phase-locked loop (PLL), and a digital rotator, estimating a frequency difference between a carrier frequency of the received signal and the LO reference frequency, and applying the estimated frequency difference to the RF PLL and the digital rotator.
Claims26
A method for wireless communications, comprising:
- receiving a signal in a receiver having a resampler, having a local oscillator producing a reference frequency, having a radio frequency phase-locked loop, and having a digital rotator;
- estimating a frequency difference between a carrier frequency of the received signal and the local oscillator reference frequency;
- applying a portion of the estimated frequency difference to the radio frequency phase-locked loop;
- applying a remaining portion of the estimated frequency difference to the digital rotator;
- and
- configuring the resampler based on the remaining portion of the estimated frequency difference applied to the digital rotator simultaneously with applying the portion of the estimated frequency difference to the radio frequency phase-locked loop and applying the remaining portion to the digital rotator.
An apparatus for wireless communications, comprising:
- a receiver for receiving a signal, the receiver comprising:
- a resampler;
- a local oscillator producing a reference frequency;
- a radio frequency phase-locked loop;
- and
- a digital rotator;
- and
- at least one processor configured to:
- estimate a frequency difference between a carrier frequency of the received signal and the local oscillator reference frequency;
- apply a portion of the estimated frequency difference to the radio frequency phase-locked loop;
- apply a remaining portion of the estimated frequency difference to the digital rotator;
- and
- correct a sampling time error by configuring the resampler based on the remaining portion of the estimated frequency difference applied to the digital rotator, wherein the at least one processor is configured to simultaneously correct the sampling time error and apply the portion of the estimated frequency difference and the remaining portion of the estimated frequency difference.
An apparatus for wireless communications, comprising:
- means for receiving a signal, comprising:
- a local oscillator producing a reference frequency;
- a radio frequency phase-locked loop;
- and
- a digital rotator;
- and
- means for estimating a frequency difference between a carrier frequency of the received signal and the local oscillator reference frequency;
- means for applying a portion of the estimated frequency difference to the radio frequency phase-locked loop;
- and
- means for applying a remaining portion of the estimated frequency difference to the digital rotator.
A computer program product for wireless communications, comprising:
- a non-transitory computer-readable medium having code for causing a computer to perform a method, the method comprising:
- receiving a signal in a receiver having a resampler, having a local oscillator producing a reference frequency, having a radio frequency phase-locked loop, and having a digital rotator;
- estimating a frequency difference between a carrier frequency of the received signal and the local oscillator reference frequency;
- applying a portion of the estimated frequency difference to the radio frequency phase-locked loop;
- applying a remaining portion of the estimated frequency difference to the digital rotator;
- and
- configuring the resampler based on the remaining portion of the estimated frequency difference applied to the digital rotator simultaneously with applying the portion of the estimated frequency difference to the radio frequency phase-locked loop and applying the remaining portion to the digital rotator.
Dependencies are inferred from the claim text.