METHOD AND APPARATUS FOR REDUCING SUCCESSIVE PRE-REGISTRATION ATTEMPTS BY ACCESS TERMINALS

• US 20100075680A1
• Filed: 09/22/2009
• Published: 03/25/2010
• Est. Priority Date: 09/23/2008
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Ramachandran, Shyamal, Swaminathan, Arvind, Klingenbrunn, Thomas, Balasubramanian, Srinivasan
• Granted Patent: US 9,066,309 B2
• Time in Patent Office: Days
• US Class Current: 455/436
• CPC Class Codes: H04W 36/0005 Control or signalling for completing the hand-off
• CPC Class Codes: H04W 60/00 Affiliation to network, e.g. registration; Terminating affiliation with the network, e.g. de-registration
• CPC Class Codes: H04W 60/04 using triggered events

Abstract

An access terminal pre-registers with a second access network via a first access network to ensure a quick handover in the future. Frequent pre-registration attempts are avoided by implementing a hysteresis timer that restricts when a pre-registration process can be initiated. The hysteresis timer is started when pre-registration is initiated by the access terminal. No new pre-registration attempts are permitted if the hysteresis timer has not expired. An abort condition can cause the hysteresis timer to be aborted early, and a new pre-registration can be initiated. Access points in the first access network may be grouped into one or more pre-registration zones. If the access terminal moves from a first access point to a second access point, a new pre-registration is skipped if the first and second access points have the same pre-registration zone or the second access point is aware of the pre-registration zone for the first access point.

Claims

1. A method operational in an access terminal, comprising:

starting a timer after a pre-registration with a second access network is performed by the access terminal via a first access network;

preventing additional pre-registrations with the second access network prior to expiration of the timer unless an abort condition occurs; and

performing a second pre-registration prior to the expiration of the timer if an abort condition has occurred.

2. The method of claim 1, wherein the abort condition occurs when a serving cell signal quality falls below a signal quality threshold.

3. The method of claim 1, wherein the abort condition occurs when an indication of an impending handoff from the first access network to the second access network is obtained and the access terminal lacks a valid pre-registration with the second access network.

4. The method of claim 1, wherein the timer has a fixed duration so as to extend the time between pre-registration attempts by the access terminal.

5. The method of claim 1, wherein the timer is a hysteresis timer.

6. The method of claim 1 further comprising:

determining that the first access network allows pre-registration with the second access network.

7. The method of claim 1, further comprising:

receiving a pre-registration indicator and a first pre-registration zone identifier from a serving first access point of the first access network.

8. The method of claim 7, wherein the pre-registration indicator determines whether the first access network allows pre-registration with the second access network.

9. The method of claim 7, wherein the access terminal stores the received first pre-registration zone associated with the first access point.

10. The method of claim 7, further comprising:

receiving a secondary pre-registration zone list associated with the first pre-registration zone.

11. The method of claim 7, wherein as the access terminal moves from the first serving access point to a second serving access point within the first access network, the method further comprises:

obtaining a second pre-registration zone for the second serving access point;

comparing the second pre-registration zone to the first pre-registration zone; and

preventing a new pre-registration if the first pre-registration zone and the second pre-registration zone are the same.

12. The method of claim 11, further comprises:

obtaining a secondary pre-registration zone list for the second serving access point;

comparing the first pre-registration zone to one or more zones in the secondary pre-registration zone list; and

preventing a new pre-registration if the first pre-registration zone is found in the secondary pre-registration zone list.

13. The method of claim 12, further comprising:

performing a new pre-registration with the second access network via the second serving access point of the first access network if the first pre-registration zone is distinct from the second pre-registration zone and the zones in the secondary pre-registration zone list.

14. The method of claim 1, wherein the first access network and second access network are distinct wireless networks.

15. The method of claim 14, wherein the first access network is a Long Term Evolution network and the second access network is an Evolved High Rate Packet Data network.

16. The method of claim 1, wherein pre-registration includes exchanging one or more messages with the second access network through a communication tunnel via the first access network.

17. The method of claim 1, wherein pre-registration of the access terminal with the second access network permits a subsequent communication handoff between the first access network and the second access network without delay.

18. An access terminal, comprising:

a wireless communication interface having multi-mode capabilities to communicate over a first access network and a second access network;

a processing circuit coupled to the wireless communication interface, the processing circuit adapted to

start a timer after a pre-registration with the second access network is performed by the access terminal via the first access network;

prevent additional pre-registrations with the second access network prior to expiration of the timer unless an abort condition occurs; and

perform a second pre-registration prior to the expiration of the timer if an abort condition occurs.

19. The access terminal of claim 18, wherein the wireless communication interface communicates with just one of the first access network and the second access network at any one time.

20. The access terminal of claim 18, wherein the processing circuit is further adapted to

obtain a first pre-registration zone identifier from a serving first access point of the first access network, wherein the first pre-registration zone identifier is associated with a plurality of access points in the first access network;

and

obtain a secondary pre-registration zone list associated with the first pre-registration zone.

21. The access terminal of claim 20, wherein as the access terminal moves from the first serving access point to a second serving access point within the first access network, the processing circuit is further adapted to

obtain a second pre-registration zone for the second serving access point;

compare the second pre-registration zone to the first pre-registration zone; and

prevent a new pre-registration if the first pre-registration zone and the second pre-registration zone are the same.

22. The access terminal of claim 21, wherein the processing circuit is further adapted to

obtain a secondary pre-registration zone list for the second serving access point;

compare the first pre-registration zone to one or more zones in the secondary pre-registration zone list; and

prevent a new pre-registration if the first pre-registration zone is found in the secondary pre-registration zone list.

23. An access terminal, comprising:

means for starting a timer after a pre-registration with a second access network is performed by the access terminal via a first access network;

means for preventing additional pre-registrations with the second access network prior to expiration of the timer unless an abort condition occurs; and

means for performing a second pre-registration prior to the expiration of the timer if an abort condition has occurred.

24. A method operational in an access point of a first access network, comprising:

obtaining a first pre-registration zone identifier, where the first pre-registration zone identifier identifies a group of access points within the first access network;

obtaining a secondary pre-registration zone list that includes zone identifiers associated with the first pre-registration zone identifier; and

advertising the first pre-registration zone identifier and the secondary pre-registration zone list to one or more access terminals in a cell covered by the access point.

25. The method of claim 24, further comprising:

obtaining a pre-registration indicator from the first access network;

receiving a pre-registration request with a second access network from an access terminal operating within a cell covered by the access point; and

routing the pre-registration request to the second access network if the pre-registration indicator indicates that such pre-registration is allowed.

26. The method of claim 24, wherein the first pre-registration zone identifier and the secondary pre-registration zone list is utilized by receiving access terminals in a cell covered by the access point to determine whether a new pre-registration is needed with a second access network via the access point of the first access network.

27. An access point, comprising:

a wireless network interface to communicate with access terminals in a cell within a first access network;

a network interface to communicate with a second access network; and

a processing circuit coupled to the wireless network interface and the network interface, the processing circuit adapted to

obtain a first pre-registration zone identifier, where the pre-registration zone identifier identifies a group of access points within the first access network;

obtain a secondary pre-registration zone list that includes zone identifiers associated with the first pre-registration zone identifier; and

advertise the first pre-registration zone identifier and the secondary pre-registration zone list to one or more access terminals in a cell covered by the access point.

28. The access point of claim 27, wherein the processing circuit is further adapted to

obtain a pre-registration indicator from the first access network;

receive a pre-registration request with a second access network from an access terminal operating within a cell covered by the access point; and

route the pre-registration request to the second access network if the pre-registration indicator indicates that such pre-registration is allowed.

29. An access point, comprising:

means for obtaining a first pre-registration zone identifier, where the pre-registration zone identifier identifies a group of access points within a first access network;

means for obtaining a secondary pre-registration zone list that includes zone identifiers associated with the first pre-registration zone identifier; and

means for advertising the first pre-registration zone identifier and the secondary pre-registration zone list to one or more access terminals in a cell covered by the access point.

30. The access point of claim 29, further comprising:

means for obtaining a pre-registration indicator from the first access network;

means for receiving a pre-registration request with a second access network from an access terminal operating within a cell covered by the access point; and

means for routing the pre-registration request to the second access network if the pre-registration indicator indicates that such pre-registration is allowed.

31. A method operational in a network server of a first access network, comprising:

grouping a plurality of cells in a first access network into one or more cell groups;

associating a first cell group with a first pre-registration zone;

generating a secondary zone list for the first pre-registration zone, where the secondary zone list excludes the first pre-registration zone; and

distributing the first pre-registration zone and the secondary zone list to access points within the cells for the first cell group.

32. The method of claim 31, wherein the first pre-registration zone and the secondary zone list is utilized by receiving access terminals to determine whether a new pre-registration is needed with a second access network via the first access network.

33. The method of claim 31, further comprising:

distributing the pre-registration indicator; and

generating a pre-registration indicator based on whether the first access network allows access terminals to pre-register with a second access network via the first access network.

34. A network server, comprising:

an intra-network interface to communicate with access points within a first access network;

an inter-network interface to communicate with a second access network; and

a processing circuit coupled to the intra-network interface and the inter-network interface, the processing circuit adapted to

group a plurality of cells in a first access network into one or more cell groups;

associate a first cell group with a first pre-registration zone;

generate a secondary zone list for the first pre-registration zone, where the secondary zone list excludes the first pre-registration zone; and

distribute the first pre-registration zone and the secondary zone list to access points within the cells for the first cell group.

35. The method of claim 34, wherein the first pre-registration zone and the secondary zone list is utilized by receiving access terminals to determine whether a new pre-registration is needed with the second access network via the first access network.

36. A network server, comprising:

means for grouping a plurality of cells in a first access network into one or more cell groups;

means for associating a first cell group with a first pre-registration zone;

means for generating a secondary zone list for the first pre-registration zone, where the secondary zone list excludes the first pre-registration zone; and

means for distributing the first pre-registration zone and the secondary zone list to access points within the cells for the first cell group.

37. A method for deploying access points and pre-registration zones within a first access network, comprising:

advertising a first pre-registration zone identifier from a first group of access points;

advertising a second pre-registration zone identifier from a second group of access points; and

deploying a third group of access points to form a boundary zone between the first group of access points and the second group of access points.

38. The method of claim 37, further comprising:

advertising the third pre-registration zone identifier from the third group of access points; and

advertising the first pre-registration zone identifier and second pre-registration zone identifier in a secondary pre-registration zone list from the third group of access points.

39. The method of claim 38, wherein the secondary pre-registration zone list excludes the third pre-registration zone identifier.

40. The method of claim 37, further comprising:

assigning the first pre-registration zone identifier to the first group of access points;

assigning the second pre-registration zone identifier to the second group of access points; and

assigning the third pre-registration zone identifier to the third group of access points.

41. The method of claim 37, wherein the first pre-registration zone identifier, first pre-registration zone identifier, and the third pre-registration zone identifier are the same zone identifier.