CELL SELECTION METHOD AND MOBILE STATION

• US 20100267385A1
• Filed: 11/14/2008
• Published: 10/21/2010
• Est. Priority Date: 11/16/2007
• Status: Active Grant

• Current Assignee: NTT Docomo Incorporated (Nippon Telegraph and Telephone Corporation)
• Original Assignee: NTT Docomo Incorporated (Nippon Telegraph and Telephone Corporation)
• Inventors: Iwamura, Mikio, Nakamura, Takehiro
• Granted Patent: US 8,670,768 B2
• Time in Patent Office: Days
• US Class Current: 455/435.200
• CPC Class Codes: H04W 48/06 based on traffic conditions
• CPC Class Codes: H04W 48/20 Selecting an access point
• CPC Class Codes: H04W 60/04 using triggered events

Abstract

A cell selection method includes steps of: (A) determining, at a mobile station (UE), whether or not a first CSG cell satisfies a predetermined condition, when using a first macro cell as a camped cell; and (B) changing, at the mobile station (UE), the camped cell from the first macro cell to a first CSG cell, when determined that the first CSG cell satisfies the predetermined condition.

Claims

1. A cell selection method in which a mobile station selects a camped cell among a specific cell selectable as a camped cell only by a specific mobile station and a general cell selectable as a camped cell by any mobile station, the cell selection method comprising steps of:

(A) determining, at the mobile station, whether or not a predetermined condition is satisfied, when using a first general cell as the camped cell; and

(B) changing, at the mobile station, the camped cell from the first general cell to a first specific cell, when determined that the predetermined condition is satisfied.

2. The cell selection method according to claim 1, wherein

in the step (A), the mobile station determines whether or not the predetermined condition is satisfied, when using the first general cell as the camped cell, and when determined that the mobile station is located in the general cell which at least partially overlaps the first specific cell that regards the mobile station as the specific mobile station.

3. The cell selection method according to claim 1, wherein

a first frequency used by the first specific cell is different from a second frequency used by the first general cell;

and

when determined that the first specific cell has best radio quality among cells using the first frequency, and when determined that the radio quality in the first specific cell satisfies first radio quality, the mobile station determines that the predetermined condition is satisfied, in the step (A), and changes the camped cell from the first general cell to the first specific cell, in the step (B).

4. The cell selection method according to claim 1, wherein

a first frequency used by the first specific cell is different from a second frequency used by the first general cell;

and

when determined that a difference between radio quality in the first specific cell and best radio quality among cells using the first frequency is within a predetermined offset, and determined that the radio quality in the first specific cell satisfies first radio quality, the mobile station determines that the predetermined condition is satisfied, in the step (A), and changes the camped cell from the first general cell to the first specific cell, in the step (B).

5. The cell selection method according to claim 1, wherein

when determined that radio quality in the first specific cell satisfies first radio quality, the mobile station determines that the predetermined condition is satisfied, in the step (A), and changes the camped cell from the first general cell to the first specific cell, in the step (B).

6. The cell selection method according to claim 1, further comprising a step of:

(C) setting, at the mobile station, a second specific cell as the camped cell, when not detected a general cell that satisfies second radio quality, and when detected the second specific cell that does not regard the mobile station as the specific mobile station and satisfies third radio quality.

7. The cell selection method according to claim 6, further comprising a step of:

changing, at the mobile station, the camped cell from the second specific cell to a second general cell, when using the second specific cell as the camped cell, and when detected a second general cell that satisfies the second radio quality.

23. The cell selection method according to claim 2, further comprising a step of:

(C) setting, at the mobile station, a second specific cell as the camped cell, when not detected a general cell that satisfies second radio quality, and when detected the second specific cell that does not regard the mobile station as the specific mobile station and satisfies third radio quality.

24. The cell selection method according to claim 3, further comprising a step of:

(C) setting, at the mobile station, a second specific cell as the camped cell, when not detected a general cell that satisfies second radio quality, and when detected the second specific cell that does not regard the mobile station as the specific mobile station and satisfies third radio quality.

25. The cell selection method according to claim 4, further comprising a step of:

(C) setting, at the mobile station, a second specific cell as the camped cell, when not detected a general cell that satisfies second radio quality, and when detected the second specific cell that does not regard the mobile station as the specific mobile station and satisfies third radio quality.

26. The cell selection method according to claim 5, further comprising a step of:

(C) setting, at the mobile station, a second specific cell as the camped cell, when not detected a general cell that satisfies second radio quality, and when detected the second specific cell that does not regard the mobile station as the specific mobile station and satisfies third radio quality.

35. The cell selection method according to claim 23, further comprising a step of:

changing, at the mobile station, the camped cell from the second specific cell to a second general cell, when using the second specific cell as the camped cell, and when detected a second general cell that satisfies the second radio quality.

36. The cell selection method according to claim 24, further comprising a step of:

changing, at the mobile station, the camped cell from the second specific cell to a second general cell, when using the second specific cell as the camped cell, and when detected a second general cell that satisfies the second radio quality.

37. The cell selection method according to claim 25, further comprising a step of:

changing, at the mobile station, the camped cell from the second specific cell to a second general cell, when using the second specific cell as the camped cell, and when detected a second general cell that satisfies the second radio quality.

38. The cell selection method according to claim 26, further comprising a step of:

changing, at the mobile station, the camped cell from the second specific cell to a second general cell, when using the second specific cell as the camped cell, and when detected a second general cell that satisfies the second radio quality.

8. A mobile station configured to select a camped cell among a specific cell selectable as a camped cell only by a specific mobile station and a general cell selectable as a camped cell by any mobile station, the mobile station comprising:

a cell selector unit configured to determine whether or not a predetermined condition is satisfied when using a first general cell as a camped cell, and to change the camped cell from the first general cell to a first specific cell when determined that the predetermined condition is satisfied.

9. The mobile station according to claim 8, wherein

the cell selector unit is configured to determine whether or not the predetermined condition is satisfied, when using the first general cell as the camped cell, and when determined that the mobile station is located in the general cell which at least partially overlaps the first specific cell that regards the mobile station as the specific mobile station.

10. The mobile station according to claim 8, wherein

a first frequency used by the first specific cell is different from a second frequency used by the first general cell;

and

when determined that the first specific cell has best radio quality among cells using the first frequency, and that the radio quality in the first specific cell satisfies first radio quality, the cell selector unit is configured to determine that the predetermined condition is satisfied, and to change the camped cell from the first general cell to the first specific cell.

11. The mobile station according to claim 8, wherein

a first frequency used by the first specific cell is different from a second frequency used by the first general cell;

and

when determined that a difference between radio quality in the first specific cell and best radio quality among cells using the first frequency is within a predetermined offset, and determined that the radio quality in the first specific cell satisfies first radio quality, the cell selector unit is configured to determine that the predetermined condition is satisfied, and to change the camped cell from the first general cell to the first specific cell.

12. The mobile station according to claim 8, wherein

when determined that radio quality in the first specific cell satisfies first radio quality, the cell selector unit is configured to determine that the predetermined condition is satisfied, and to change the camped cell from the first general cell to the first specific cell.

13. The mobile station according to claim 8, wherein

when not detected a general cell that satisfies second radio quality, and when detected a second specific cell that does not regard the mobile station as the specific mobile station and satisfies third radio quality, the cell selector unit is configured to set the second specific cell as the camped cell.

14. The mobile station according to claim 13, wherein

when using the second specific cell as the camped cell, and when detected a second general cell that satisfies the second radio quality, the cell selector unit is configured to change the camped cell from the second specific cell to the second general cell.

27. The mobile station according to claim 9, wherein

when not detected a general cell that satisfies second radio quality, and when detected a second specific cell that does not regard the mobile station as the specific mobile station and satisfies third radio quality, the cell selector unit is configured to set the second specific cell as the camped cell.

28. The mobile station according to claim 10, wherein

when not detected a general cell that satisfies second radio quality, and when detected a second specific cell that does not regard the mobile station as the specific mobile station and satisfies third radio quality, the cell selector unit is configured to set the second specific cell as the camped cell.

29. The mobile station according to claim 11, wherein

when not detected a general cell that satisfies second radio quality, and when detected a second specific cell that does not regard the mobile station as the specific mobile station and satisfies third radio quality, the cell selector unit is configured to set the second specific cell as the camped cell.

30. The mobile station according to claim 12, wherein

when not detected a general cell that satisfies second radio quality, and when detected a second specific cell that does not regard the mobile station as the specific mobile station and satisfies third radio quality, the cell selector unit is configured to set the second specific cell as the camped cell.

15. A cell selection method in which a mobile station selects a camped cell among a first cell using a first frequency and a second cell using a second frequency different from the first frequency, the cell selection method comprising a step of:

changing, at the mobile station which uses the first cell as the camped cell, the camped cell from the first cell to the second cell, when a priority level of the second cell is higher than a priority level of the first cell, and when determined that radio quality in the second cell satisfies predetermined radio quality.

18. The cell selection method according to claim 15, wherein

the mobile station changes the camped cell from the first cell to the second cell, when the second cell is a specific cell selectable as a camped cell only by a specific mobile station, and when determined that a difference between radio quality in the second cell and best radio quality among cells using the second frequency is within a predetermined offset.

16. A cell selection method in which a mobile station selects a camped cell among a first cell using a first frequency and a second cell using a second frequency different from the first frequency, the cell selection method comprising a step of:

changing, at the mobile station which uses the first cell as the camped cell, the camped cell from the first cell to the second cell, when a priority level of the second cell is the same as a priority level of the first cell, and when determined that radio quality in the second cell satisfies predetermined radio quality and that radio quality in the first cell does not satisfy predetermined radio quality.

31. The cell selection method according to claim 16, wherein

the mobile station changes the camped cell from the first cell to the second cell, when the second cell is a specific cell selectable as a camped cell only by a specific mobile station, and when determined that a difference between radio quality in the second cell and best radio quality among cells using the second frequency is within a predetermined offset.

17. A cell selection method in which a mobile station selects a camped cell among a first cell using a first frequency and a second cell using a second frequency different from the first frequency, the cell selection method comprising a step of:

changing, at the mobile station which uses the first cell as the camped cell, the camped cell from the first cell to the second cell, when a priority level of the second cell is lower than a priority level of the first cell, and when determined that radio quality in the second cell satisfies predetermined radio quality and that radio quality in the first cell does not satisfy predetermined radio quality.

32. The cell selection method according to claim 17, wherein

the mobile station changes the camped cell from the first cell to the second cell, when the second cell is a specific cell selectable as a camped cell only by a specific mobile station, and when determined that a difference between radio quality in the second cell and best radio quality among cells using the second frequency is within a predetermined offset.

19. A mobile station configured to select a camped cell among a first cell using a first frequency and a second cell using a second frequency different from the first frequency, the mobile station comprising:

a cell selector unit configured to change the camped cell from the first cell to the second cell, when a priority level of the second cell is higher than a priority level of the first cell, when the first cell is used as the camped cell, and when determined that radio quality in the second cell satisfies predetermined radio quality.

22. The mobile station according to claim 19, wherein

the cell selector unit is configured to change the camped cell from the first cell to the second cell, when the second cell is a specific cell selectable as a camped cell only by a specific mobile station, and when determined that a difference between radio quality in the second cell and best radio quality among cells using the second frequency is within a predetermined offset.

20. A mobile station configured to select a camped cell among a first cell using a first frequency and a second cell using a second frequency different from the first frequency, the mobile station comprising:

a cell selector unit configured to change the camped cell from the first cell to the second cell, when a priority level of the second cell is the same as a priority level of the first cell, when the first cell is used as the camped cell, and when determined that radio quality in the second cell satisfies predetermined radio quality and that radio quality in the first cell does not meet predetermined radio quality.

33. The mobile station according to claim 20, wherein

the cell selector unit is configured to change the camped cell from the first cell to the second cell, when the second cell is a specific cell selectable as a camped cell only by a specific mobile station, and when determined that a difference between radio quality in the second cell and best radio quality among cells using the second frequency is within a predetermined offset.

21. A mobile station configured to select a camped cell among a first cell using a first frequency and a second cell using a second frequency different from the first frequency, the mobile station comprising:

a cell selector unit configured to change the camped cell from the first cell to the second cell, when a priority level of the second cell is lower than a priority level of the first cell, when the first cell is used as the camped cell, and when determined that radio quality in the second cell satisfies predetermined radio quality and that radio quality in the first cell does not meet predetermined radio quality.

34. The mobile station according to claim 21, wherein

the cell selector unit is configured to change the camped cell from the first cell to the second cell, when the second cell is a specific cell selectable as a camped cell only by a specific mobile station, and when determined that a difference between radio quality in the second cell and best radio quality among cells using the second frequency is within a predetermined offset.