Cell re-selection in a cellular telecommunications network
View Patent ↗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.
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.