Systems, methods, and apparatus for activity control in a wireless communications device

• US 8,385,878 B2
• Filed: 06/28/2006
• Issued: 02/26/2013
• Est. Priority Date: 06/28/2005
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Rao, Anil S., Rao, Subramanya P.
• Primary Examiner(s): TRAN, PABLO N
• Application Number:
  US11/478,258
• Publication Number:
  US 20070178875A1
• Time in Patent Office: 2,435 Days
• Field of Search: 455/343.2, 455/343.3, 455/343.4, 455/574, 455/127.5, 455/127.1, 455/458
• US Class Current: 455/343.2
• CPC Class Codes: H04W 52/028 switching on or off only a part of the equipment circuit blocks
• CPC Class Codes: H04W 56/0035 detecting errors in frequency or phase
• CPC Class Codes: Y02D 30/70 in wireless communication networks

Abstract

Embodiments include methods of activity control in which a time of initiation of an active period of a discontinuous reception (DRX) cycle is based on a value calculated with respect to a wireless signal received during an active period of a previous DRX cycle.

Claims

1. A method of activity control, comprising:

receiving a signal during an active period of a first discontinuous reception (DRX) cycle;

determining an estimate of a characteristic of the signal;

calculating a predicted duration of a track time within a future DRX cycle to track frequency or timing for an active period of a second DRX cycle based on the estimate of the characteristic of the signal; and

scheduling start time of the second DRX cycle based on the predicted duration of the track time.

2. The method of activity control according to claim 1, wherein the estimate is based on correcting a frequency error of an oscillator with respect to the received signal.

3. The method of activity control according to claim 1, wherein the estimate is based on correcting a timing error with respect to the received signal.

4. The method of activity control according to claim 1, wherein the estimate is based on correcting a code phase error with respect to the received signal.

5. The method of activity control according to claim 1, wherein calculating the predicted duration of the track time includes calculating the predicted duration of the track time of at least one of a frequency tracking loop or a time tracking loop.

6. The method of activity control according to claim 5, wherein the calculating the predicted duration of the track time comprises:

determining frequency and timing errors accumulated during transient phases of demodulation of the received signal; and

adjusting the at least one of the frequency loop or the time tracking loop based on the determined frequency and timing errors.

7. The method of activity control according to claim 6, wherein the determining comprises analyzing a plurality of received signals based at least in part upon a convergence function according to worst-case channel conditions, the convergence function indicating the starting time of the second DRX cycle within a defined error tolerance.

8. The method of activity control according to claim 1, further comprising determining, during an active period of a third DRX cycle occurring prior to the first and second DRX cycles, a second estimate of a characteristic of a second signal based on a second received signal, wherein the calculating the predicted duration of the track time is based on the second estimate of the characteristic of the second signal.

9. The method of activity control according to claim 1, wherein scheduling the starting time includes selecting an interval from among a plurality of intervals.

10. The method of activity control according to claim 1, further comprising programming a sleep timer according to the scheduled starting time.

11. A non-transitory data storage medium having machine-executable instructions stored thereon, that if executed by a machine, cause the machine to execute the method of activity control according to claim 1.

12. The method of activity control according to claim 1, wherein determining the estimate of the characteristic of the signal is based on a plot signal-to-noise ratio.

13. The method of claim 1, wherein scheduling the start time of the second DRX cycle further comprises calculating backwards from a time when a paging signal is expected to arrive.

14. An apparatus for wireless communications,comprising:

an oscillator configured to produce a frequency reference;

a radio-frequency (RF) receiver arranged to receive the frequency reference and a signal during an active period of a first discontinuous reception (DRX) cycle according to the frequency reference;

a track time predictor configured to determine an estimate of a characteristic of the signal;

a calculator configured to calculate a predicted duration of a track time within a future DRX cycle to track frequency or timing for an active period of a second DRX cycle based on the estimate of the characteristic of the signal; and

a sleep timer configured to schedule a start time of the second DRX cycle based on the predicted duration of the track time and to activate the oscillator during the active period of the second DRX cycle.

15. The apparatus for wireless communications according to claim 14, wherein said apparatus includes a frequency tracking loop configured to correct a frequency error of the oscillator with respect to the received signal, wherein the calculator is configured to calculate the predicted duration of the track time based on the corrected frequency error.

16. The apparatus for wireless communications according to claim 14, wherein said RF receiver includes a time tracking loop configured to correct a timing error with respect to the received signal, wherein the calculator is configured to calculate the predicted duration of the track time based on the corrected timing error.

17. The apparatus for wireless communications according to claim 16, wherein the calculator is further configured to:

determine frequency and timing errors accumulated during transient phases of demodulation of the received signal; and

adjust the at least one of the frequency tracking loop or the time tracking loop based on the determined frequency and timing errors.

18. The apparatus for wireless communications according to claim 17, wherein the calculator is further configured to analyze a plurality of received signals based at least in part upon a convergence function according to worst-case channel conditions, the convergence function indicating the starting time of the second DRX cycle within a defined error tolerance.

19. The apparatus for wireless communications according to claim 14, wherein said RF receiver includes a code tracking loop configured to correct a code phase error with respect to the received signal, wherein said calculator is configured to calculate the predicted of the track time based on the corrected code phase error.

20. The apparatus for wireless communications according to claim 14, wherein the track time predictor is configured to estimate a second estimate of a characteristic of a second signal based on a second signal received during an active period of a third DRX cycle occurring prior to the first and second DRX cycles.

21. The apparatus for wireless communications according to claim 14, wherein the sleep timer is configured to select an interval from among a plurality of intervals and activate the oscillator according to the selected interval.

22. The apparatus for wireless communications according to claim 14, wherein said calculator is configured to calculate the predicted duration of the track time for at least one of a frequency error or a timing error.

23. The apparatus for wireless communications according to claim 14, wherein said apparatus includes a lookup table, and wherein said calculator is configured to select a value from said lookup table and wherein the sleep timer is configured to schedule the starting time based on the selected value.

24. The apparatus for wireless communications according to claim 14, wherein the apparatus is a portable wireless communication device.

25. The apparatus for wireless communications according to claim 14, wherein said apparatus is a cellular telephone.

26. The apparatus for wireless communications according to claim 14, wherein the track time predictor is further configured to determine the estimate of the characteristic of the signal based on a pilot signal-to-noise ratio.

27. The apparatus of claim 14, wherein the sleep timer is further configured to schedule the start time of the second DRX cycle by calculating backwards from a time when a paging signal is expected to arrive.

28. An apparatus for wireless communications, comprising:

means for receiving a signal during an active period of a first discontinuous reception (DRX) cycle

means for determining an estimate of a characteristic of the signal;

means for calculating a predicted duration of a track time within a future DRX cycle to track frequency or timing for an active period of a second DRX cycle based on the estimate of the characteristic of the signal; and

means for scheduling a start time of the second DRX cycle based on the predicted duration of the track time.

29. The apparatus for wireless communications according to claim 28, wherein said means for determining is configured to correct a frequency error of an oscillator with respect to the received signal.

30. The apparatus for wireless communications according to claim 28, wherein said means for determining is configured to correct a timing error with respect to the received signal.

31. The apparatus for wireless communications according to claim 28, wherein said means for determining is configured to correct a code phase error with respect to the received signal.

32. The apparatus for wireless communications according to claim 28, wherein said means for determining configured to estimate a second estimate of a characteristic of a second signal based on a second signal received during an active period of a third DRX cycle occurring prior to the first and second DRX cycle, wherein the means for calculating the predicted duration of the track time is configured to calculate the predicted duration of the track time based on the estimate of the characteristic of the second signal.

33. The apparatus for wireless communications according to claim 28, wherein said means for scheduling the starting time is configured to select an interval from among a plurality of intervals.

34. The apparatus for wireless communications according to claim 28, wherein said means for scheduling a starting time is configured to program a sleep timer according to the scheduling starting time.

35. The apparatus for wireless communications according to claim 28, wherein the apparatus is a portable wireless communication device.

36. The apparatus for wireless communications according to claim 28, wherein said apparatus is a cellular telephone.

37. The apparatus for wireless communications according to claim 28, wherein the means for determining further comprises determining the estimate of the characteristic of the signal based on a pilot signal-to-noise ratio.

38. The apparatus of claim 28, wherein the means for scheduling is further configured to schedule the start time of the second DRX cycle by calculating backwards from a time when a paging signal is expected to arrive.

39. A method of activity control, comprising:

during an active period of a first discontinuous reception (DRX) cycle, receiving a wireless signal;

during a paging slot within the active period of the first DRX cycle, monitoring a paging channel; and

calculating, based on a received signal strength of the wireless signal, a starting time for an active period of a second DRX cycle subsequent to the first DRX cycle, wherein calculating the starting time includes;

calculating a predicted track time of at least one of a frequency tracking loop or a time tracking loop by determining frequency and timing errors accumulated during transient phases of demodulation of the received signal strength of the wireless signal and adjusting the at least one of the frequency tracking loop or the time tracking loop based on the determined frequency and timing errors; and

calculating the starting time based on the predicted track time.

40. The method of activity control according to claim 39, wherein determining the frequency and timing error further comprises analyzing a plurality of received wireless signals based at least in part upon a convergence function according to worst-case channel conditions, the convergence function indicating the starting time of the second DRX cycle within a defined error tolerance.

41. An apparatus for wireless communications, comprising:

an oscillator configured to produce a frequency reference;

a radio-frequency (RF) receiver arranged to receive the frequency reference, wherein the RF receiver is configured to receive a wireless signal according to the frequency reference;

a sleep timer configured to activate the oscillator during an active period of each of a plurality of discontinuous reception (DRX) cycles;

wherein the RF receiver is configured to monitor a paging channel during a paging slot within the active period of the first one of the plurality of DRX cycles and wherein the RF receiver includes a time tracking loop configured to correct a timing error with respect to the received signal; and

a calculator configured to calculate, based on a received signal strength of the wireless signal and the corrected timing error, a starting time for an active period of a second one of the plurality of the DRX cycles that is subsequent to the first DRX cycle, wherein the calculator is further configured to;

determine frequency and timing errors accumulated during transient phases of demodulation of the received signal strength of the wireless signal; and

adjust the at least one of the frequency tracking loop or the time tracking loop based on the determined frequency and timing errors.

42. The apparatus for wireless communications according to claim 41, wherein the calculator is further configured to analyze a plurality of received wireless signals based at least in part upon a convergence function according to worst-case channel conditions, the convergence function indicating the starting time of the second DRX cycle within a defined error tolerance.

43. An apparatus for wireless communications, comprising:

means for receiving a wireless signal during an active period of a first discontinuous reception (DRX) cycle, wherein the means for receiving is configured to monitor a paging channel during a paging slot within the active period of the first DRX cycle and wherein the means for receiving includes means for correcting a timing error with respect to the received signal; and

means for calculating, based on a received signal strength of the wireless signal and the corrected timing error, a starting time for an active period of a second DRX cycle subsequent to the first DRX cycle, wherein the means for calculating is further includes;

means for determining frequency and timing errors accumulated during transient phases of demodulation of the received signal strength of the wireless signal; and

means for adjusting the at least one of the frequency tracking loop or the time tracking loop based on the determined frequency and timing errors.

44. The apparatus for wireless communications according to claim 43, wherein the means for calculating is further include means for analyzing a plurality of received wireless signals based at least in part upon a convergence function according to worst-case channel conditions, the convergence function indicating the starting time of the second DRX cycle within a defined error tolerance.