Inter-frequency handoff

• US 8,229,433 B2
• Filed: 10/27/2005
• Issued: 07/24/2012
• Est. Priority Date: 10/27/2005
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Parekh, Nileshkumar J., Ulupinar, Fatih, Prakash, Rajat
• Primary Examiner(s): Edouard, Patrick
• Assistant Examiner(s): Ho, Huy C
• Application Number:
  US11/261,804
• Publication Number:
  US 20070099619A1
• Time in Patent Office: 2,462 Days
• Field of Search: 455/436, 370/331
• US Class Current: 455/436
• CPC Class Codes: H04W 36/18 for allowing seamless reselection, e.g. soft reselection
• CPC Class Codes: H04W 36/30 by measured or perceived connection quality data

Abstract

Embodiments are described in connection with seamless inter-frequency handoff in a wireless network. Provided is a method that includes reporting to an access network sector pilot strength information for at least one frequency member in a message specified in an active set management protocol. Information regarding at least another frequency member is received in a message specified in the active set management protocol. The method further includes ascertaining whether to handoff from one frequency member to another frequency member and can further include seamlessly handing off to the other frequency member.

Claims

1. A method for seamless inter-frequency handoff in a wireless network, comprising:

reporting to an access network a sector pilot strength information for a first frequency member in a message specified in an active set management protocol;

receiving pilot timing information for a second frequency member in a message specified in the active set management protocol, wherein the first frequency member is operating at a different frequency than the second frequency member;

generating a tune-away schedule for a first frequency member based on a frame boundary timing for the first frequency member and the pilot timing information for the second frequency member;

periodically tuning to the second frequency member based on the generated tune-away schedule to perform pilot strength measurements for the second frequency member;

if the measured pilot strength for the second frequency member exceeds a threshold, adding to the second frequency member to a same active set as the first frequency member and establishing a radio link with the access network for the second frequency member;

ascertaining whether to handoff from the first frequency member to the second frequency member, wherein both the first and the second frequency members are included in the same active set; and

seamlessly handing off to the second frequency member.

2. The method of claim 1, further comprising handing off to the second frequency member when a channel quality level of the first frequency member falls below another threshold.

3. The method of claim 1, wherein generating a tune-away schedule, further comprising determining a time to initiate a temporary tune-away to the frequency of the second frequency member.

4. The method of claim 3, the tune-away comprising discontinuing monitoring forward link channels associated with the access network.

5. The method of claim 3, the tune-away comprising discontinuing communications to the access network over a reverse link.

6. The method of claim 1, reporting a sector pilot strength information for the first frequency member, further comprising using a first receiver for communication and a second receiver to report the sector pilot strength.

7. The method of claim 1, wherein the message specified in the active set management protocol for reporting the sector pilot strength information is a PilotReport message.

8. The method of claim 1, wherein the message specified in the active set management protocol for receiving the second frequency member is an ActiveSetAssignment message.

9. The method of claim 1, wherein seamlessly handing off to the second frequency member is during an idle session.

10. The method of claim 1, wherein seamlessly handing off to the second frequency member is during an active session.

11. The method of claim 1, wherein the seamless inter-frequency handoff from the first frequency member to the second frequency member is performed if the radio link will not be interrupted.

12. The method of claim 1, wherein the seamless inter-frequency handoff from the first frequency member to the second frequency member is not performed if there will be an interruption in a radio link.

13. The method of claim 1, wherein the tune-away schedule includes a tune-away time parameter, a tune-away duration parameter, and a tune-away periodicity parameter.

14. The method of claim 1, wherein before tuning to the second frequency member to perform pilot strength measurements for the second frequency member, requesting a permission of the access network to tune away from the first frequency member.

15. An apparatus for seamless inter-frequency handoff in a wireless communication environment, comprising:

means for reporting to a radio access network pilot strength information for a first sector operation at a first frequency;

means for receiving pilot timing information for a second sector operating at a second frequency, wherein the first frequency is different from the second frequency;

means for generating a tune-away schedule for a first sector based on a frame boundary timing for the first sector and the pilot timing information for the second sector;

means for periodically tuning to the second sector based on the generated tune-away schedule to perform pilot strength measurements for the second sector;

means for establishing a radio link with the second sector if the measured pilot strength for the second sector exceeds a threshold;

means for adding the second sector to a same active set as the first sector;

means for ascertaining whether to handoff from the first sector to the second sector; and

means for seamlessly performing an inter-frequency handoff between the first and the second sectors included in the same active set.

16. The apparatus of claim 15, further comprising means for temporarily tuning-away to the second sector while in a connected mode with the first sector.

17. The apparatus of claim 15, further comprising means for receiving messages during a connected mode.

18. The apparatus of claim 15, wherein the means for reporting responds to a SectorParameters message specified in an overhead messages protocol.

19. The apparatus of claim 15, wherein the means for seamlessly performing an inter-frequency handoff receives an ActiveSetAssignment message specified in an active set management protocol.

20. The apparatus of claim 15, wherein the tune-away schedule includes a tune-away time parameter, a tune-away duration parameter, and a tune-away periodicity parameter.

21. The apparatus of claim 15, wherein means for periodically tuning to the second sector to perform pilot strength measurements comprise means for requesting a permission from the first sector to tune away from the first sector.

22. A method for seamless inter-frequency handoff, comprising the steps of:

generating a plurality of tune-away schedules for a plurality of different frequency members, wherein a tune-away schedule is based on a frame boundary timing for a first frequency member and pilot timing information for a second frequency member, where in the first and second frequency members operate at different frequencies;

receiving a request for a tune-away period from an access terminal operating at a first frequency member in accordance with associated tune-away schedule;

sending a permission message to the access terminal to tune-away;

receiving from an access terminal a sector pilot strength information for the first frequency member in a message specified in an active set management protocol;

sending information about a second frequency member in a message specified in the active set management protocol, wherein both the first and the second frequency members are included in a same active set; and

allowing the access terminal to seamlessly hand off to the second frequency member.

23. The method, of claim 22, wherein the tune-away includes discontinuing communication to the access terminal over a forward link.

24. The method of claim 22, wherein the tune-away includes discontinuing monitoring a reverse link channel associated with the access terminal.

25. The method of claim 22, wherein the step of allowing the access terminal to seamlessly hand off to the second frequency member is during an idle session.

26. The method of claim 22, wherein the step of allowing the access terminal to seamlessly hand off to the second frequency member is during an active session.

27. The method of claim of claim 22, wherein the step of allowing the access terminal to seamlessly hand off to the second frequency member is performed if there will be an uninterrupted radio link.

28. The method of claim 22, wherein the step of allowing the access terminal to seamlessly hand off to the second frequency member is not performed if there will be an interruption in a radio link.

29. The method of claim 22, wherein the tune-away schedule includes a tune-away time parameter, a tune-away duration parameter, and a tune-away periodicity parameter.

30. An access network that provides for seamless inter-frequency handoff in a wireless communication system, comprising:

a receiver that receives a tune-away request from a mobile device in accordance with a tune-away schedules generated by the mobile device based on a frame boundary timing for a first frequency member and pilot timing information for a second frequency member, wherein the first and second frequency members operate at different frequencies;

a processor that determines whether the mobile device may tune away from the first frequency member to the second frequency member based in part on the tune-away schedule; and

a transmitter that sends an ActiveSetAssignment message that notifies the mobile device that the first and second frequency members are to be included in a same active set of the mobile device, whereby the mobile device can seamlessly hand off from the first frequency member to the second frequency member.

31. The access network of claim 30, wherein the transmitter further requests at least a second access network to respond with resources that are available for the mobile device.

32. The access network of claim 30, wherein the receiver further receives resource information from at least a second access network.

33. The access network of claim 30, wherein the tune-away schedule includes a tune-away time parameter, a tune-away duration parameter, and a tune-away periodicity parameter.