Method and apparatus to optimize off-frequency pilot searching by wireless mobile station

• US 7,623,861 B2
• Filed: 12/05/2002
• Issued: 11/24/2009
• Est. Priority Date: 12/05/2002
• Status: Expired due to Fees

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Yoon, Steven, Joshi, Abhay Arvind, Neufeld, Arthur James, Ekvetchavit, Thunyachate
• Primary Examiner(s): Harper; Vincent P
• Assistant Examiner(s): Figueroa; Marisol
• Application Number:
  US10/313,750
• Publication Number:
  US 20040203838A1
• Time in Patent Office: 2,546 Days
• Field of Search: 455436-439, 455/450, 455443-444
• US Class Current: 455/436
• CPC Class Codes: H04W 48/20 Selecting an access point
• CPC Class Codes: H04W 52/0225 using monitoring of external events, e.g. the presence of a signal
• CPC Class Codes: H04W 52/0245 according to signal strength
• CPC Class Codes: Y02D 30/70 in wireless communication networks

Abstract

A wireless mobile telephone (400) is operated so as manage the performance of “off-frequency searches,” that is, searches for base station pilot signals that differ in frequency from the pilot signals in the mobile station'"'"'s active set. Whenever frequency searching is performed (such as responsive to emerging from a reduced-power sleep mode), the mobile station performs on-frequency pilot signal searching (902) upon a prescribed active set frequency. Only if a prescribed off-frequency searching condition (903-908) is satisfied, the mobile station additionally performs off-frequency pilot signal searching (912) upon one or more neighboring base stations'"'"' frequencies.

Claims

1. A method for operating a wireless mobile station, comprising:

operating in an idle mode including wakeup cycles and sleep cycles, wherein each of the wakeup cycles includes an on-frequency searching time period and an off-frequency searching time period, wherein the wireless mobile telephone has a first power requirement during the wakeup cycles and has a second power requirement less than the first power requirement during the sleep cycles, wherein the wireless mobile telephone is adapted to enable a receiving function during the wakeup cycles and to disable the receiving function during the sleep cycles, and wherein the wireless mobile telephone is adapted to disable a transmitting function during the idle mode and to enable the transmitting function when not in the idle mode;

transitioning from a sleep cycle in the idle mode to a wakeup cycle in the idle mode;

determining whether an off-frequency searching condition is satisfied during the wakeup cycle, the off-frequency searching condition being satisfied when a maximum signal-to-noise ratio for one or more base stations in an active set of the wireless mobile telephone is less than a prescribed level and there are no on-frequency base stations included in a candidate set of the wireless mobile telephone;

performing off-frequency pilot signal searching during the off-frequency searching time period in the wakeup cycle upon at least one other frequency for at least one neighboring base station not in the active set for the wireless mobile telephone when the off-frequency searching condition is satisfied;

performing on-frequency pilot signal searching during the on-frequency searching time period in the wakeup cycle upon at least one frequency for at least one base station in the active set for the wireless mobile telephone when the off-frequency searching condition is satisfied or not satisfied, wherein the performing the on-frequency pilot signal searching occurs before or after the performing of the off-frequency pilot signal searching when the off-frequency searching condition is satisfied; and

transitioning from the wakeup cycle to the sleep cycle if additional communication is not required.

2. The method of claim 1, where:

the off-frequency pilot signal searching is performed after all on-frequency pilot signal searching has concluded to avoid retuning back to the at least one frequency for the at least one base station in the active set.

3. The method of claim 1, where:

the on-frequency pilot signal searching is completed before commencing any off-frequency pilot signal searching.

32. The method of claim 1, wherein the off-frequency searching condition is determined based on results of the on-frequency pilot signal searching.

33. The method of claim 1, wherein the off-frequency searching condition is selected to avoid off-frequency pilot signal searching when likelihood of requiring off-frequency handoff is low.

4. A method for operating a wireless mobile communications device, comprising:

operating in an idle mode including wakeup cycles and sleep cycles, wherein each of the wakeup cycles includes an on-frequency searching time period and an off-frequency searching time period, wherein the wireless mobile communications device has a first power requirement during the wakeup cycles and has a second power requirement less than the first power requirement during the sleep cycles, wherein the wireless mobile communications device is adapted to enable a receiving function during the wakeup cycles and to disable the receiving function during the sleep cycles, and wherein the wireless mobile communications device is adapted to disable a transmitting function during the idle mode and to enable the transmitting function when not in the idle mode;

transitioning from a sleep cycle in the idle mode to a wakeup cycle in the idle mode;

determining whether an off-frequency searching condition is satisfied during the wakeup cycle, the off-frequency searching condition being satisfied when a maximum signal-to-noise ratio for one or more base stations in an active set of the wireless mobile communications device is less than a prescribed level and there are no on-frequency base stations included in a candidate set of the wireless mobile communications device;

performing off-frequency pilot signal searching during the off-frequency searching time period in the wakeup cycle upon at least one other frequency for at least one neighboring base station not in the active set for the wireless mobile communications device when the off-frequency searching condition is satisfied;

performing on-frequency pilot signal searching during the on-frequency searching time period in the wakeup cycle upon at least one frequency for at least one base station in the active set for the wireless mobile communications device when the off-frequency searching condition is satisfied or not satisfied; and

transitioning from the wakeup cycle to the sleep cycle if additional communication is not required.

5. The method of claim 4, further comprising:

performing off-frequency pilot signal searching during the off-frequency searching time period in the wakeup cycle upon the at least one other frequency for the at least one neighboring base station not in the active set for the wireless mobile communications device when the off-frequency searching condition is satisfied, wherein the performing the on-frequency pilot signal searching occurs before or after the performing of the off-frequency pilot signal searching when the off-frequency searching condition is satisfied.

6. The method of claim 4, where the determining whether the off-frequency searching condition is satisfied comprises

determining whether a count of base stations in the active set is less than a prescribed number.

7. The method of claim 4, where the determining whether the off-frequency searching condition is satisfied comprises

determining whether a count of base stations included in a candidate set of the device and utilizing the at least one frequency does not exceed a prescribed number.

8. The method of claim 4, where the determining whether the off-frequency searching condition is satisfied comprises

determining whether candidate and non-candidate neighbor sets of the device collectively include at least a prescribed number of base stations utilizing frequencies different than the at least one frequency.

9. The method of claim 4, where the determining whether an off-frequency searching condition is satisfied comprises determining whether:

a count of base stations in the active set is less than a prescribed number;

a maximum signal-to-noise ratio for the at least one base station in the active set is less than a prescribed level;

a count of base stations included in a candidate set of the device and utilizing the at least one frequency is not exceeding a prescribed number;

or

candidate and non-candidate neighbor sets of the device collectively include at least a prescribed number of base stations utilizing frequency different than the at least one frequency.

10. A computer-readable medium embodying computer-executable instructions to perform a method, comprising:

operating in an idle mode including wakeup cycles and sleep cycles, wherein each of the wakeup cycles includes an on-frequency searching time period and an off-frequency searching time period, wherein the wireless mobile telephone has a first power requirement during the wakeup cycles and has a second power requirement less than the first power requirement during the sleep cycles, wherein the wireless mobile telephone is adapted to enable a receiving function during the wakeup cycles and to disable the receiving function during the sleep cycles, and wherein the wireless mobile telephone is adapted to disable a transmitting function during the idle mode and to enable the transmitting function when not in the idle mode;

transitioning from a sleep cycle in the idle mode to a wakeup cycle in the idle mode;

determining whether an off-frequency searching condition is satisfied during the wakeup cycle, the off-frequency searching condition being satisfied when a maximum signal-to-noise ratio for one or more base stations in an active set of the wireless mobile telephone is less than a prescribed level and there are no on-frequency base stations included in a candidate set of the wireless mobile telephone;

performing off-frequency pilot signal searching during the off-frequency searching time period in the wakeup cycle upon at least one other frequency for at least one neighboring base station not in the active set for the wireless mobile telephone when the off-frequency searching condition is satisfied;

performing on-frequency pilot signal searching during the on-frequency searching time period in the wakeup cycle upon at least one frequency for at least one base station in the active set for the wireless mobile telephone when the off-frequency searching condition is satisfied or not satisfied, wherein the performing the on-frequency pilot signal searching occurs before or after the performing of the off-frequency pilot signal searching when the off-frequency searching condition is satisfied; and

transitioning from the wakeup cycle to the sleep cycle if additional communication is not required.

11. The medium of claim 10, wherein off-frequency pilot signal searching is performed after all on-frequency pilot signal searching has concluded to avoid retuning back to the at least one frequency for the at least one base station in the active set.

12. The medium of claim 10, wherein the operation of on-frequency pilot signal searching is completed before commencing any off-frequency pilot signal searching.

13. A computer-readable medium embodying computer-executable instructions to perform a method, comprising:

operating in an idle mode including wakeup cycles and sleep cycles, wherein each of the wakeup cycles includes an on-frequency searching time period and an off-frequency searching time period, wherein the wireless communications device has a first power requirement during the wakeup cycles and has a second power requirement less than the first power requirement during the sleep cycles, wherein the wireless communications device is adapted to enable a receiving function during the wakeup cycles and to disable the receiving function during the sleep cycles, and wherein the wireless communications device is adapted to disable a transmitting function during the idle mode and to enable the transmitting function when not in the idle mode;

transitioning from a sleep cycle in the idle mode to a wakeup cycle in the idle mode;

determining whether an off-frequency searching condition is satisfied during the wakeup cycle, the off-frequency searching condition being satisfied when a maximum signal-to-noise ratio for one or more base stations in an active set of the wireless mobile communications device is less than a prescribed level and there are no on-frequency base stations included in a candidate set of the wireless mobile communications device;

performing off-frequency pilot signal searching during the off-frequency searching time period in the wakeup cycle upon at least one other frequency for at least one neighboring base station not in the active set for the wireless communications device when the off-frequency searching condition is satisfied;

performing on-frequency pilot signal searching during the on-frequency searching time period in the wakeup cycle upon at least one frequency for at least one base station in the active set for the wireless communications device when the off-frequency searching condition is satisfied or not satisfied; and

transitioning from the wakeup cycle to the sleep cycle if additional communication is not required.

14. The medium of claim 13, further adapted for:

performing off-frequency pilot signal searching during the off-frequency searching time period in the wakeup cycle upon the at least one other frequency for the at least one neighboring base station not in the active set for the wireless communications device when the off-frequency searching condition is satisfied, wherein the performing the on-frequency pilot signal searching occurs before or after the performing of the off-frequency pilot signal searching when the off-frequency searching condition is satisfied.

15. The medium of claim 13, wherein the determining whether the off-frequency searching condition is satisfied comprises determining whether a count of base stations in the active set is less than a prescribed number.

16. The medium of claim 13, wherein the determining whether the off-frequency searching condition is satisfied comprises determining whether a count of base stations included in a candidate set of the device and utilizing the at least one frequency does not exceed a prescribed number.

17. The medium of claim 13, wherein the determining whether the off-frequency searching condition is satisfied comprises determining whether candidate and non-candidate neighbor sets of the device collectively include at least a prescribed number of base stations utilizing frequency different than the at least one frequency.

18. The medium of claim 13, wherein the determining whether an off-frequency searching condition is satisfied comprises determining whether

a count of base stations in the active set is less than a prescribed number;

a maximum signal-to-noise ratio for the at least one base station in the active set is less than a prescribed level;

a count of base stations included in a candidate set of the device and utilizing the at least one frequency is not exceeding a prescribed number;

or

candidate and non-candidate neighbor sets of the device collectively include at least a prescribed number of base stations utilizing frequency different than the at least one frequency.

19. Circuitry including multiple interconnected electrically conductive elements configured to perform operations to manage a wireless mobile telephone, the operations comprising:

operating in an idle mode including wakeup cycles and sleep cycles, wherein each of the wakeup cycles includes an on-frequency searching time period and an off-frequency searching time period, wherein the wireless mobile telephone has a first power requirement during the wakeup cycles and has a second power requirement less than the first power requirement during the sleep cycles, wherein the wireless mobile telephone is adapted to enable a receiving function during the wakeup cycles and to disable the receiving function during the sleep cycles, and wherein the wireless mobile telephone is adapted to disable a transmitting function during the idle mode and to enable the transmitting function when not in the idle mode;

transitioning from a sleep cycle in the idle mode to a wakeup cycle in the idle mode;

determining whether a predetermined off-frequency searching condition is satisfied during the wakeup cycle, the off-frequency searching condition being satisfied when a maximum signal-to-noise ratio for one or more base stations in an active set of the wireless mobile communications device is less than a prescribed level and there are no on-frequency base stations included in a candidate set of the wireless mobile communications device;

performing off-frequency pilot signal searching during the off-frequency searching time period in the wakeup cycle upon at least one other frequency for at least one neighboring base station not in the active set for the wireless mobile telephone when the off-frequency searching condition is satisfied; and

performing on-frequency pilot signal searching during the on-frequency searching time period in the wakeup cycle upon at least one frequency for at least one base station in the active set for the wireless mobile telephone when the off-frequency searching condition is satisfied or not satisfied, wherein the performing the on-frequency pilot signal searching occurs before or after the performing of the off-frequency pilot signal searching when the off-frequency searching condition is satisfied; and

transitioning from the wakeup cycle to the sleep cycle if additional communication is not required.

20. The circuitry of claim 19, where:

the operation of off-frequency pilot signal searching is performed after all on-frequency pilot signal searching has concluded to avoid retuning back to the at least one frequency for the at least one base station in the active set.

21. The circuitry of claim 19, where:

the operation of off-frequency pilot signal searching is completed before commencing any on-frequency pilot signal searching.

22. Circuitry including multiple interconnected electrically conductive elements configured to perform operations to operate a wireless communications device, the operations comprising:

operating in an idle mode including wakeup cycles and sleep cycles, wherein each of the wakeup cycles includes an on-frequency searching time period and an off-frequency searching time period, wherein the wireless communications device has a first power requirement during the wakeup cycles and has a second power requirement less than the first power requirement during the sleep cycles, wherein the wireless communications device is adapted to enable a receiving function during the wakeup cycles and to disable the receiving function during the sleep cycles, and wherein the wireless communications device is adapted to disable a transmitting function during the idle mode and to enable the transmitting function when not in the idle mode;

transitioning from a sleep cycle in the idle mode to a wakeup cycle in the idle mode;

determining whether a predetermined off-frequency searching condition is satisfied during the wakeup cycle, the off-frequency searching condition being satisfied when a maximum signal-to-noise ratio for one or more base stations in an active set of the wireless mobile communications device is less than a prescribed level and there are no on-frequency base stations included in a candidate set of the wireless mobile communications device;

performing off-frequency pilot signal searching during the off-frequency searching time period in the wakeup cycle upon at least one other frequency for at least one neighboring base station not in the active set for the wireless communications device when the off-frequency searching condition is satisfied;

performing on-frequency pilot signal searching during the on-frequency searching time period in the wakeup cycle upon at least one frequency for at least one base station in the active set for the wireless communications device when the off-frequency searching condition is satisfied or not satisfied; and

transitioning from the wakeup cycle to the sleep cycle if additional communication is not required.

23. The circuitry of claim 22, the operations further comprising:

performing off-frequency pilot signal searching during the off-frequency searching time period in the wakeup cycle upon the at least one other frequency for the at least one neighboring base station not in the active set for the wireless communications device when the off-frequency searching condition is satisfied, wherein the performing the on-frequency pilot signal searching occurs before or after the performing of the off-frequency pilot signal searching when the off-frequency searching condition is satisfied.

24. The circuitry of claim 22, where the operation of determining whether the predetermined off-frequency searching condition is satisfied comprises determining whether a count of base stations in the active set is less than a prescribed number.

25. The circuitry of claim 22, where the operation of determining whether the predetermined off-frequency searching condition is satisfied comprises determining whether a count of base stations included in a candidate set of the device and utilizing the at least one frequency does not exceed a prescribed number.

26. The circuitry of claim 22, where the operation of determining whether the predetermined off-frequency searching condition is satisfied comprises determining whether candidate and non-candidate neighbor sets of the device collectively include at least a prescribed number of base stations utilizing frequency different than the at least one frequency.

27. The circuitry of claim 22, where the operation of determining whether a predetermined off-frequency searching condition is satisfied comprises determining whether

a count of base stations in the active set is less than a prescribed number;

a maximum signal-to-noise ratio for the at least one base station in the active set is less than a prescribed level;

a count of base stations included in a candidate set of the device and utilizing the at least one frequency is not exceeding a prescribed number;

or

candidate and non-candidate neighbor sets of the device collectively include at least a prescribed number of base stations utilizing frequency different than the at least one frequency.

28. A wireless mobile telephone, comprising:

a transceiver;

a speaker;

a microphone;

a user interface;

a manager, coupled to the transceiver, speaker, microphone, and user interface, and programmed for;

operating in an idle mode including wakeup cycles and sleep cycles, wherein each of the wakeup cycles includes an on-frequency searching time period and an off-frequency searching time period, wherein the wireless mobile telephone has a first power requirement during the wakeup cycles and has a second power requirement less than the first power requirement during the sleep cycles, wherein the wireless mobile telephone is adapted to enable a receiving function during the wakeup cycles and to disable the receiving function during the sleep cycles, and wherein the wireless mobile telephone is adapted to disable a transmitting function during the idle mode and to enable the transmitting function when not in the idle mode;

transitioning from a sleep cycle in the idle mode to a wakeup cycle in the idle mode;

determining whether an off-frequency searching condition is satisfied during the wakeup cycle, the off-frequency searching condition being satisfied when a maximum signal-to-noise ratio for one or more base stations in an active set of the wireless mobile telephone is less than a prescribed level and there are no on-frequency base stations included in a candidate set of the wireless mobile telephone;

performing off-frequency pilot signal searching during the off-frequency searching time period in the wakeup cycle upon at least one other frequency for at least one neighboring base station not in the active set for the wireless mobile telephone when the off frequency searching condition is satisfied;

performing on-frequency pilot signal searching during the on-frequency searching time period in the wakeup cycle upon at least one frequency for at least one base station in the active set for the wireless mobile telephone when the off-frequency searching condition is satisfied or not satisfied, wherein the performing the on-frequency pilot signal searching occurs before or after the performing of the off-frequency pilot signal searching when the off-frequency searching condition is satisfied; and

transitioning from the wakeup cycle to the sleep cycle if additional communication is not required.

29. A wireless communications device, comprising:

a transceiver;

a speaker;

a microphone;

a user interface; and

a manager, coupled to the transceiver, speaker, microphone, and user interface, comprising;

means for operating in an idle mode including wakeup cycles and sleep cycles, wherein each of the wakeup cycles includes an on-frequency searching time period and an off-frequency searching time period, wherein the wireless communications device has a first power requirement during the wakeup cycles and has a second power requirement less than the first power requirement during the sleep cycles, wherein the wireless communications device is adapted to enable a receiving function during the wakeup cycles and to disable the receiving function during the sleep cycles, and wherein the wireless communications device is adapted to disable a transmitting function during the idle mode and to enable the transmitting function when not in the idle mode;

means for transitioning from a sleep cycle in the idle mode to a wakeup cycle in the idle mode;

means for determining whether an off-frequency searching condition is satisfied during the wakeup cycle, the off-frequency searching condition being satisfied when a maximum signal-to-noise ratio for one or more base stations in an active set of the wireless communications device is less than a prescribed level and there are no on-frequency base stations included in a candidate set of the wireless communications device;

means for performing off-frequency pilot signal searching during the off-frequency searching time period in the wakeup cycle upon at least one other frequency for at least one neighboring base station not in the active set for the wireless communications device when the off-frequency searching condition is satisfied;

means for performing on-frequency pilot signal searching during the on-frequency searching time period in the wakeup cycle upon at least one frequency for at least one base station in the active set for the wireless communications device when the off-frequency searching condition is satisfied or not satisfied; and

means for transitioning from the wakeup cycle to the sleep cycle if additional communication is not required.

30. A wireless mobile telephone, comprising:

transceiver means for wireless transmitting and receiving signals;

speaker means for producing audio output;

microphone means for a microphone;

user interface means for receiving user input and providing human-readable output; and

manager means, coupled to the transceiver means, speaker means, microphone means, and user interface means, comprising;

means for operating in an idle mode including wakeup cycles and sleep cycles, wherein each of the wakeup cycles includes an on-frequency searching time period and an off-frequency searching time period, wherein the wireless mobile telephone has a first power requirement during the wakeup cycles and has a second power requirement less than the first power requirement during the sleep cycles, wherein the wireless mobile telephone is adapted to enable a receiving function during the wakeup cycles and to disable the receiving function during the sleep cycles, and wherein the wireless mobile telephone is adapted to disable a transmitting function during the idle mode and to enable the transmitting function when not in the idle mode;

means for transitioning from a sleep cycle in the idle mode to a wakeup cycle in the idle mode;

means for determining whether an off-frequency searching condition is satisfied during the wakeup cycle, the off-frequency searching condition being satisfied when a maximum signal-to-noise ratio for one or more base stations in an active set of the wireless mobile telephone is less than a prescribed level and there are no on-frequency base stations included in a candidate set of the wireless mobile telephone;

means for performing off-frequency pilot signal searching during the off-frequency searching time period in the wakeup cycle upon at least one other frequency for at least one neighboring base station not in the active set for the wireless mobile telephone when the off-frequency searching condition is satisfied;

means for performing on-frequency pilot signal searching during the on-frequency searching time period in the wakeup cycle upon at least one frequency for at least one base station in the active set for the wireless mobile telephone when the off-frequency searching condition is satisfied or not satisfied, wherein the performing the on-frequency pilot signal searching occurs before or after the performing of the off-frequency pilot signal searching when the off-frequency searching condition is satisfied; and

means for transitioning from the wakeup cycle to the sleep cycle if additional communication is not required.

31. A wireless communications device, comprising:

transceiver means for wireless transmitting and receiving signals;

speaker means for producing audio output;

microphone means for a microphone;

user interface means for receiving user input and providing human-readable output;

manager means, coupled to the transceiver means, speaker means, microphone means, and user interface means, for performing operations comprising;

operating in an idle mode including wakeup cycles and sleep cycles, wherein each of the wakeup cycles includes an on-frequency searching time period and an off-frequency searching time period, wherein the wireless communications device has a first power requirement during the wakeup cycles and has a second power requirement less than the first power requirement during the sleep cycles, wherein the wireless communications device is adapted to enable a receiving function during the wakeup cycles and to disable the receiving function during the sleep cycles, and wherein the wireless communications device is adapted to disable a transmitting function during the idle mode and to enable the transmitting function when not in the idle mode;

transitioning from a sleep cycle in the idle mode to a wakeup cycle in the idle mode;

determining whether a predetermined off-frequency searching condition is satisfied during the wakeup cycle, the off-frequency searching condition being satisfied when a maximum signal-to-noise ratio for one or more base stations in an active set of the wireless communications device is less than a prescribed level and there are no on-frequency base stations included in a candidate set of the wireless communications device;

performing off-frequency pilot signal searching during the off-frequency searching time period in the wakeup cycle upon at least one other frequency for at least one neighboring base station not in the active set for the wireless communications device when the off-frequency searching condition is satisfied;

performing on-frequency pilot signal searching during the on-frequency searching time period in the wakeup cycle upon at least one frequency for at least one base station in the active set for the wireless communications device when the off-frequency searching condition is satisfied or not satisfied; and

transitioning from the wakeup cycle to the sleep cycle if additional communication is not required.