CELL SELECTION IN MOBILE COMMUNICATIONS

• US 20110136489A1
• Filed: 02/15/2011
• Published: 06/09/2011
• Est. Priority Date: 05/06/2004
• Status: Active Grant

• Current Assignee: Malikie Innovations Limited (Key Patent Innovations Limited)
• Original Assignee: M-Stack Limited (Blackberry Limited)
• Inventors: George, Richard, Funnell, Nicola M., Farnsworth, Andrew, de Jong, Gjalt, Roberts, Gideon
• Granted Patent: US 8,554,266 B2
• Time in Patent Office: Days
• US Class Current: 455/436
• CPC Class Codes: H04W 36/24 Reselection being triggered by specific parameters

Abstract

Mobile user equipment for use in a cellular communications environment performs an improved cell selection on transitions out of a connected mode state. The transitions might be from one connected mode state to another or from a connected mode state to idle mode. The improvement in cell selection lies in assembling the list of candidate cells prior to cell selection. In the prior art, the list of candidate cells would usually be restricted to the serving cell or active cells supporting communication between the equipment and the network prior to transition. In embodiments of the invention, the list might comprise cells which are not the serving cell or which are outside the active set, for example a network-preferred cell or cells neighbouring the serving cell or cells of the active set.

Claims

1. Cell selection apparatus for use in mobile communications equipment to select a cell from a candidate set of cells to support subsequent communication between a cellular network and the equipment, said apparatus being triggerable, by a transition of the equipment out of an existing connected mode state in which communication is supported by a serving cell or an active set of one or more cells, to select said cell,

wherein the apparatus is adapted to use as said candidate set a set of cells comprising at least one cell which is not a cell supporting the existing connected mode state and

further comprising parameter adjustment means for adjusting at least one parameter for at least one of the candidate set of cells, thereby changing a probability that said at least one cell will be selected.

2. Cell selection apparatus according to claim 1 wherein said at least one cell comprises a cell identified to the mobile communications equipment by the network.

3. Cell selection apparatus according to claim 1 wherein said at least one cell comprises a cell neighbouring a cell supporting the existing connected mode state.

4. Cell selection apparatus according to claim 1 wherein said at least one cell comprises a cell identified by information stored by the mobile communications equipment.

5. Cell selection apparatus according to claim 4 wherein said information stored comprises historic cell-related information arising from past behaviour of the mobile communications equipment.

6. Cell selection apparatus according to claim 4 wherein said information stored concerns power measurement data in relation to said at least one cell.

7. Cell selection apparatus according to claim 1 comprised by channel configuration apparatus in the mobile communications equipment for configuring a communication channel in the cellular network.

8. Cell selection apparatus according to claim 1 wherein said parameter adjustment means is adapted to select a cell identified to the mobile communications equipment by the network for said adjustment.

9. Mobile communications equipment comprising cell selection apparatus according to claim 1.

10. Mobile communications equipment according to claim 9, further comprising power measurement equipment for taking power measurements with respect to cells of the candidate set of cells, wherein the selection of a cell is based at least in part on said power measurements.

11. Mobile communications equipment according to claim 9, further comprising an algorithm store for storing at least one selection algorithm for use in assembling a candidate set of cells.

12. Mobile communications equipment according to claim 9, further comprising a data store for storing system information for use in identifying one or more cells neighbouring a cell supporting the existing connected mode state.

13. Mobile communications equipment according to claim 9, further comprising a data store for storing data relevant to historic cell-related information arising from past behaviour of the mobile communications equipment.

14. Mobile communications equipment according to claim 9, further comprising a data store for storing cell power measurement data.

15. Mobile communications equipment according to claim 9, wherein the network comprises a UMTS-based network.

16. Mobile communications equipment according to claim 9 wherein said transition of the equipment comprises a transition from a state in which it has a dedicated channel to a state in which it is camped on a cell.

17. Mobile communications equipment according to claim 15 wherein said existing connected mode state comprises any one of Cell_DCH, Cell_FACH, Cell_PCH, and URA_PCH.

18. Mobile communications equipment according to claim 9 wherein said transition of the equipment out of an existing connected mode state comprises a transition to an idle mode.

19. Mobile communications equipment according to claim 15 wherein said transition of the equipment out of an existing connected mode state comprises one of the following transitions:

a) Cell_DCH to Cell_FACH, Cell_PCH, or URA_PCH;

b) Cell_FACH to Cell_FACH, Cell_PCH, or URA_PCH; and

c) Cell_FACH or Cell_DCH to an idle mode.

20. A method of selecting a cell of a cellular network to support subsequent communications between the network and mobile communications equipment on transition of the equipment out of an existing connected mode state in which communication is supported by a serving cell or an active set of one or more cells, which method comprises:

i) assembling a candidate list of cells; and

ii) selecting a cell from the candidate list,

wherein operation i) comprises identifying for said candidate list at least one cell which is not a cell supporting the existing connected mode state, said at least one cell meeting one or more predetermined criteria and

further comprising adjusting a value for at least one parameter of a cell in the candidate list, prior to operation ii), so as to change the likelihood of selection of said cell.

21. A method according to claim 20 which further comprises the operation of receiving an input identifying a transition from the existing connected mode state of the mobile communications equipment.

22. A method according to claim 20 which further comprises the operation of receiving data identifying a network-preferred cell, and wherein the at least one cell comprises said network-preferred cell.

23. A method according to claim 20 wherein said operation of adjusting a value comprises adjusting a value for at least one parameter of the network-preferred cell.

24. A method according to claim 20, further comprising the operation of storing system information for use in identifying said at least one cell.

25. A method according to claim 20 which further comprises the operation of storing historic cell-related information arising from past behaviour of the mobile communications equipment, for use in identifying said at least one cell.

26. A method according to claim 20 which further comprises the operation of storing cell power measurement data, for use in identifying said at least one cell.

27. A method according to claim 20 wherein operation ii) is carried out by reference to power measurements for the cells of the candidate list.