Cell re-selection in a cellular telecommunications network

• US 8,630,647 B2
• Filed: 11/30/2011
• Issued: 01/14/2014
• Est. Priority Date: 11/30/2010
• Status: Active Grant

• Current Assignee: Blackberry Limited
• Original Assignee: Blackberry Limited
• Inventors: Magadi Rangaiah, Raghavendra, Hole, David Philip, Dwyer, Johanna Lisa
• Primary Examiner(s): LE, DANH C
• Application Number:
  US13/308,030
• Publication Number:
  US 20120135731A1
• Time in Patent Office: 776 Days
• Field of Search: 455/437, 455/436, 455/439, 370/331
• US Class Current: 455/437
• CPC Class Codes: H04W 36/0085 Hand-off measurements
• CPC Class Codes: H04W 48/20 Selecting an access point
• CPC Class Codes: H04W 80/04 Network layer protocols, e.g. mobile IP [Internet Protocol]

Abstract

A wireless cellular telecommunications device stores a first parameter obtained from system information of a first cell and measures an attribute of a signal received from a candidate cell, determines if the candidate cell is a closed subscriber group cell, and evaluates the candidate cell for re-selection. If the candidate cell is determined to be a closed subscriber group cell, the evaluation of the candidate cell for re-selection is based on at least the measured attribute irrespective of the first stored parameter, that first stored parameter indicating a minimum value for the measured attribute.

Claims

1. A method in a wireless cellular telecommunications device camped on a serving cell, the device storing a parameter obtained from a first cell that is different from the serving cell, the method comprising:

measuring an attribute of a signal received from a candidate cell; and

,

evaluating the candidate cell for re-selection,

wherein, if the candidate cell has an identifier equivalent to an identifier of the first cell, the evaluation of the candidate cell for re-selection is based on at least the measured attribute and the stored parameter, else

the evaluation of the candidate cell for re-selection is performed without using the stored parameter.

2. A method according to claim 1, in which, if the candidate cell has an identifier equivalent to the identifier of the first cell, the evaluation includes determining if the candidate cell meets re-selection requirements,

wherein, if the measured attribute fails to exceed the stored parameter by a first pre-determined amount, the evaluation includes determining that the candidate cell does not meet re-selection requirements.

3. A method according to claim 2, in which the first predetermined amount is 0 dB.

4. A method according to claim 2, in which the first predetermined amount is +10 dB.

5. A method according to claim 1, in which the identifier is a locally unique identifier.

6. A method according to claim 5, in which the identifier is a physical layer identifier.

7. A method according to claim 6, in which the identifier is a primary scrambling code.

8. A method according to claim 7, in which, if the candidate cell has a carrier frequency matching a carrier frequency of the second cell and the candidate cell has a primary scrambling code matching the primary scrambling code of the second cell and the candidate cell is determined to be a closed subscriber group cell, the evaluation of the candidate cell for re-selection is based on at least the measured attribute and second stored parameter, else

the evaluation of the candidate cell for re-selection is performed without using the second stored parameter.

9. A method according to claim 6, in which the identifier of the first cell is a physical layer cell identifier.

10. A method according to claim 1, in which, if the evaluation is performed without using the stored parameter, the evaluation of the candidate cell includes:

determining if the measured attribute exceeds a predetermined default value; and

,

if the measured attribute fails to exceed the predetermined default value, determining that the candidate cell does not meet re-selection requirements.

11. A method according to claim 1, in which the candidate cell is a UTRAN cell.

12. A method according to claim 1, in which the serving cell is a GERAN cell.

13. A method according to claim 1, further comprising performing re-selection from the serving cell to the candidate cell based on the evaluation.

14. A method according to claim 1, in which the evaluation of the candidate cell includes:

acquiring system information of the candidate cell, the system information including a parameter;

determining if the measured attribute exceeds the candidate cell parameter by a second predetermined amount; and

,

if the measured attribute exceeds the candidate cell parameter by the second predetermined amount, performing re-selection to the candidate cell.

15. A method according to claim 14, in which the second predetermined amount is 0 dB.

16. A method according to claim 1, in which the stored parameter indicates a minimum required receive level.

17. A method according to claim 1, in which the measured attribute is received signal code power (RSCP).

18. A method according to claim 1, in which the serving and candidate cells are of the same wireless radio network.

19. A method according to claim 1, in which the serving and candidate cells are of different wireless radio networks.

20. A wireless cellular telecommunications device adapted to:

camp on a serving cell;

store a parameter obtained from a first cell that is different from the serving cell;

measure an attribute of a signal received from a candidate cell; and

,

evaluate the candidate cell for re-selection,

wherein, if the candidate cell has an identifier equivalent to an identifier of the first cell, the evaluation of the candidate cell for re-selection is based on at least the measured attribute and the stored parameter, else

the evaluation of the candidate cell for re-selection is performed without using the stored parameter.

21. A device according to claim 20, in which, if the candidate cell has an identifier equivalent to the identifier of the first cell, the evaluation includes determining if the candidate cell meets re-selection requirements,

wherein, if the measured attribute fails to exceed the stored parameter by a first pre-determined amount, the evaluation includes determining that the candidate cell does not meet re-selection requirements.

22. A device according to claim 21, in which the first predetermined amount is 0 dB.

23. A device according to claim 21, in which the first predetermined amount is +10 dB.

24. A device according to claim 20, in which the identifier is a locally unique identifier.

25. A device according to claim 24, in which the identifier is a physical layer identifier.

26. A device according to claim 25, in which the identifier is a primary scrambling code.

27. A device according to claim 26, in which, if the candidate cell has a carrier frequency matching a carrier frequency of the second cell and the candidate cell has a primary scrambling code matching the primary scrambling code of the second cell and the candidate cell is determined to be a closed subscriber group cell, the evaluation of the candidate cell for re-selection is based on at least the measured attribute and second stored parameter, else

the evaluation of the candidate cell for re-selection is performed without using the second stored parameter.

28. A device according to claim 24, in which the identifier of the first cell is a physical layer cell identifier.

29. A device according to claim 20, in which, if the evaluation is performed without using the stored parameter, the evaluation of the candidate cell includes:

determining if the measured attribute exceeds a predetermined default value; and

, if the measured attribute fails to exceed the predetermined default value, determining that the candidate cell does not meet re-selection requirements.

30. A device according to claim 20, in which the candidate cell is a UTRAN cell.

31. A device according to claim 20, in which the serving cell is a GERAN cell.

32. A device according to claim 20, further adapted to perform re-selection from the serving cell to the candidate cell based on the evaluation.

33. A device according to claim 20, in which the evaluation of the candidate cell includes:

acquiring system information of the candidate cell, the system information including a parameter;

determining if the measured attribute exceeds the candidate cell parameter by a second predetermined amount; and

,

if the measured attribute exceeds the candidate cell parameter by the second predetermined amount, performing re-selection to the candidate cell.

34. A device according to claim 33, in which the second predetermined amount is 0 dB.

35. A device according to claim 20, in which the stored parameter indicates a minimum required receive level.

36. A device according to claim 20, in which the measured attribute is received signal code power (RSCP).

37. A device according to claim 20, in which the serving and candidate cells are of the same wireless radio network.

38. A device according to claim 20, in which the serving and candidate cells are of different wireless radio networks.

39. A computer-readable storage medium having stored thereon instructions which can be executed by a device to:

camp on a serving cell;

store a parameter obtained from a first cell that is different from the serving cell;

measure an attribute of a signal received from a candidate cell; and

,

evaluate the candidate cell for re-selection,

wherein, if the candidate cell has an identifier equivalent to an identifier of the first cell, the evaluation of the candidate cell for re-selection is based on at least the measured attribute and the stored parameter, else

the evaluation of the candidate cell for re-selection is performed without using the stored parameter.