System and method to facilitate handover

• US 8,140,079 B2
• Filed: 07/17/2007
• Issued: 03/20/2012
• Est. Priority Date: 07/31/2006
• Status: Active Grant

• Current Assignee: Mitel Networks Incorporated (Mitel Networks Corporation)
• Original Assignee: ShoreTel Incorporated (Mitel Networks Corporation)
• Inventors: Olson, Timothy S.
• Primary Examiner(s): Bost, Dwayne
• Assistant Examiner(s): PHAM, TIMOTHY X
• Application Number:
  US11/778,831
• Publication Number:
  US 20080076430A1
• Time in Patent Office: 1,708 Days
• Field of Search: 455/440
• US Class Current: 455/440
• CPC Class Codes: H04W 36/0083 Determination of parameters used for hand-off, e.g. generation or modification of neighbour cell lists
• CPC Class Codes: H04W 36/0085 Hand-off measurements
• CPC Class Codes: H04W 36/14 Reselecting a network or an air interface
• CPC Class Codes: H04W 36/32 by location or mobility data, e.g. speed data

Abstract

A method to facilitate handover includes detecting that a mobile unit resides within at least one predetermined zone where a handover event from a first radio technology to a second radio technology may need to occur, the second radio technology being different from the first radio technology.

Claims

1. A method to facilitate handover, comprising:

storing mobility fingerprint data in memory, the mobility fingerprint data representing signal characteristics associated with, at least one predetermined handover zone where a handover event from a first radio technology to a second radio technology may need to occur, the second radio technology being different from the first radio technology, where the at least one predetermined zone resides within a region of space that is a proper subset of an overlap in coverage areas of the first and second radio technologies;

detecting that a mobile unit resides within the at least one predetermined zone based on comparing signal characteristics relative to the mobility fingerprint data;

in response to detecting the mobile unit resides in the predetermined zone, determining whether to perform the handover event; and

initiating the handover event in response to determining to perform the handover event.

2. The method of claim 1, further comprising generating a trigger signal in response to the detecting that the mobile unit resides within the at least one predetermined zone.

3. The method of claim 2 wherein initiating the handover event comprises initiating the handover event for the mobile unit from the first radio technology to the second radio technology in response to the trigger signal being generated.

4. The method of claim 1, wherein the detecting that the mobile unit resides within the at least one predetermined zone is performed by the mobile unit.

5. The method of claim 1, wherein the detecting that the mobile unit resides within the at least one predetermined zone is performed by a radio system to which the mobile unit is currently connected according to the first radio technology.

6. The method of claim 5, further comprising storing the mobility fingerprint data in memory of the radio system, the stored fingerprint data representing at least one mobility fingerprint that defines the at least one predetermined zone where the handover event may need to occur, the radio system executing instructions to evaluate the mobility fingerprint data relative to a set of received signals to ascertain whether to trigger a handover event for the mobile unit.

7. The method of claim 1, further comprising defining at least one mobility fingerprint from at least one wireless signal associated with the at least one predetermined zone where the handover event may need to occur.

8. The method of claim 7, wherein the at least one mobility fingerprint comprises a set of signals originating from different signal sources.

9. The method of claim 8, wherein the different signal sources further comprise more than one type of radio technology.

10. The method of claim 7, further comprising storing fingerprint data in memory representing signal characteristics corresponding to the at least one mobility fingerprint.

11. The method of claim 10, wherein the fingerprint data further comprises a primary identifier and at least one secondary identifier, the method further comprising allocating a greater weight to the primary identifier than to the at least one secondary identifier in evaluating whether the mobile unit resides within the at least one predetermined zone.

12. The method of claim 10, further comprising loading a fingerprint data set into memory of the mobile unit for a given area in response to detecting the mobile unit is located within a boundary for the given area, the fingerprint data set comprising the fingerprint data that defines the at least one predetermined zone where the handover may need to occur for the given area.

13. The method of claim 12, further comprising specifying key data to enable an identification of a group of a plurality of predetermined roam, zones associated with the given area, the key data being transmitted from the mobile unit and causing a predetermined fingerprint data set to be downloaded into the memory of the mobile unit for the given area.

14. The method of claim 10, further comprising prequalifying the detecting by disabling at least a portion of a signal scan if at least one wireless signal does not result in a match with the fingerprint data and enabling at least a portion of the signal scan in response to detecting that the at least one wireless signal is substantially absent from representation by the fingerprint data.

15. The method of claim 10, wherein the signal characteristics further comprise path loss associated with at least one wireless signal transmitted within a wireless network with which the mobile unit is connected, the detecting further comprising evaluating path loss from a signal scan relative to the path loss represented by the fingerprint data to determine if the mobile unit resides within the at least one predetermined zone.

16. The method of claim 10, wherein the signal characteristics further comprise measured signal strength associated with at least one wireless signal transmitted within a wireless network with which the mobile unit is connected, the detecting further comprising evaluating the measured signal strength from a signal scan relative to the signal strength represented by the fingerprint data to determine if a handover event should be triggered for the mobile unit.

17. The method of claim 7, further comprising gathering measurement data associated with the at least one predetermined zone to define the mobility fingerprint.

18. The method of claim 17, wherein the gathering of the measurement data further comprises manually positioning a test device within the at least one predetermined zone to acquire a plurality of sample measurements from the at least one wireless signal, the mobility fingerprint for each predetermined zone being generated based on the plurality of sample measurements acquired for each respective predetermined zone.

19. The method of claim 17, wherein the gathering of the measurement data further comprises adaptively collecting a set of measurement data from each of a plurality of mobile units operating near the at least one predetermined zone, the mobility fingerprint for each predetermined zone being generated based on the plurality of sample measurements acquired for each respective predetermined zone.

20. The method of claim 17, wherein the gathering of the measurement data further comprises:

importing a set of predetermined measurement data that encompasses the at least one predetermined zone; and

identifying the at least one predetermined zone based on measurement data contained in the set of imported measurement data, the mobility fingerprint for each of the at least one predetermined zone being generated based on the measurement data corresponding to the identified at least one predetermined zone.

21. The method of claim 1, wherein the at least one predetermined zone is part of a first substantially bounded area of an enterprise, the enterprise comprising a plurality of substantially bounded areas, each of the plurality of substantially bounded areas including at least one predetermined zone where a handover event may need to occur for the respective bounded area, wherein different algorithms are employed for at least two of the plurality of substantially bounded areas for evaluating whether the mobile unit resides within the at least one predetermined zone of the respective bounded area.

22. The method of, claim 1, wherein the detecting further comprises calculating at least one feasible solution by evaluating data corresponding to scanned signal characteristics relative to mobility fingerprint data that defines the at least one predetermined zone.

23. The method of claim 22, further comprising evaluating the at least one feasible solution relative to a corresponding infeasible solution to confirm the validity of the at least one feasible solution.

24. The method of claim 23, further comprising:

collecting the mobility fingerprint data at a plurality of locations proximal to the at least one predetermined zone to define a fingerprint vector; and

determining directionality associated with the mobile unit based on the fingerprint vector, the determined directionality defining at least a portion of the corresponding infeasible solution.

25. A system to facilitate handover, comprising:

a mobile unit configured to operate according to at least first radio technology and a second radio technology; and

a fingerprint detector that evaluates input data relative to mobility fingerprint data that defines at least one predetermined roam zone that is a proper subset of overlap in coverage areas between the first and second radio technologies to determine whether to trigger a handover between the first and second radio technologies for the mobile unit based on an evaluation of the mobility fingerprint data relative to the input data.

26. The system of claim 25, further comprising a fingerprint data set that includes the mobility fingerprint data for an area that includes a plurality of roam zones, the fingerprint detector generating a trigger signal in response to evaluating the input data relative to the mobility fingerprint data in the fingerprint data set.

27. The system of claim 25, wherein the input data corresponds to scanned signal characteristics, the fingerprint detector further comprising an evaluator that computes at least one feasible solution by evaluating the scanned signal characteristics relative to predefined signal characteristics defined by the mobility fingerprint data.

28. The system of claim 27, wherein the evaluator further comprises at least one discriminator programmed to confirm the validity of the at least one feasible solution.

29. The system of claim 27, wherein the scanned signal characteristics result from at least one signal scan, wherein the evaluator further comprises prequalification logic operative to control performing the at least one scan.

30. The system of claim 25, wherein the input data corresponds to scanned signal characteristics resulting from at least one signal scan, the fingerprint detector further comprising a scaling component configured to scale the scanned signal characteristics consistent with signal characteristics defined by the mobility fingerprint data.

31. The system of claim 25, wherein the fingerprint detector further comprises executable instructions running on a processor of the mobile unit.

32. The system of claim 25, wherein the fingerprint detector further comprises executable instructions running on a computer that is part of a radio system to which the mobile unit is connected according to the first radio technology.

33. The system of claim 25, further comprising:

a wireless network that operates according to the first radio technology; and

a cellular system that operates according to the second radio technology.

34. A system to facilitate handover for a mobile unit, comprising:

means for storing fingerprint data that defines, a mobility fingerprint for at least one predetermined roam zone residing within a physical space that is a proper subset of an overlap of coverage areas of a first radio technology and a second radio technology; and

means for evaluating whether to trigger a handoff for the mobile unit from the first radio technology to the second radio technology based on an evaluation of the stored fingerprint data relative to data corresponding to at least one wireless signal that is associated with the mobile unit.

35. The system of claim 34, further comprising:

means for gathering measurement data associated with the at least one predetermined zone; and

means for generating the mobility fingerprint for each of the at least one predetermined zone.