Automatic frequency control algorithm
OwnerErik Dahlback, Jonas Ohlssoninventors
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Abstract
In a mobile communication device, an automatic frequency control method and apparatus are described that are capable of minimizing the number of timing changes that have to be made due to frequency errors without increasing the overall frequency sensitivity of the receiver unit. A frequency control unit of the present invention is capable of detecting a magnitude and direction of a timing drift that may arise from a frequency error. The automatic frequency control unit thereafter adjusts the frequency of the receiver unit in such a way so as to reverse the direction of the timing drift before it becomes too large. In this way, the number of timing changes that have to be made is reduced.
Claims36
A method of controlling frequency in a mobile communication device, the method comprising:
- estimating a frequency error for the mobile communication device;
- calculating a total timing drift for the mobile communication device using the estimated frequency error;
- determining whether a magnitude of the estimated frequency error is greater than a predefined error threshold;
- determining whether a magnitude of the total timing drift is greater than a predefined drift threshold if the magnitude of the estimated frequency error is determined to be not greater than the predefined error threshold;
- and
- adjusting the frequency of the mobile communication device to reverse a direction of the total timing drift if the magnitude of the total timing drift is determined to be greater than the predefined drift threshold.
A mobile communication device, comprising:
- a transceiver unit;
- a voltage controlled oscillator adapted to generate a reference frequency signal for the transceiver unit;
- and
- a frequency control unit adapted to control the reference frequency generated by the voltage controlled oscillator, the frequency control unit configured to:
- estimate a frequency error for the mobile communication device;
- calculate a total timing drift for the mobile communication device using the estimated frequency error;
- determine whether a magnitude of the estimated frequency error is greater than a predefined error threshold;
- determine whether a magnitude of the total timing drift is greater than a predefined drift threshold if the magnitude of the estimated frequency error is determined to be not greater than the predefined error threshold;
- and
- adjust the frequency of the mobile communication device to reverse a direction of the total timing drift if the magnitude of the total timing drift is determined to be greater than the predefined drift threshold.
A method of controlling frequency in a mobile communication device, the method comprising:
- estimating a long-term frequency error and a short-term frequency error for the mobile communication device;
- calculating a total timing drift for the mobile communication device using the long-term frequency error;
- determining whether a magnitude of the short-term frequency error is greater than a predefined error threshold;
- determining whether a magnitude of the total timing drift is greater than a predefined drift threshold if the magnitude of the short-term frequency error is determined to be not greater than the predefined error threshold;
- and
- adjusting the frequency of the mobile communication device to reverse a drift direction of the total timing drift if the magnitude of the total timing drift is determined to be greater than the predefined drift threshold.
A mobile communication device, comprising:
- a transceiver unit;
- a voltage controlled oscillator adapted to generate a reference frequency signal for the transceiver unit;
- and
- a frequency control unit adapted to control the reference frequency generated by the voltage controlled oscillator, the frequency control unit configured to:
- estimate a long-term frequency error and a short-term frequency error for the mobile communication device;
- calculate a total timing drift for the mobile communication device using the long-term frequency error;
- determine whether a magnitude of the short-term frequency error is greater than a predefined error threshold;
- determine whether a magnitude of the total timing drift is greater than a predefined drift threshold if the magnitude of the short-term frequency error is determined to be not greater than the predefined error threshold;
- and
- adjust the frequency of the mobile communication device to reverse a drift direction of the total timing drift if the magnitude of the total timing drift is determined to be greater than the predefined drift threshold.
Dependencies are inferred from the claim text.