System and method for cell search and selection in a wireless communication system

• US 8,588,773 B2
• Filed: 07/29/2009
• Issued: 11/19/2013
• Est. Priority Date: 08/04/2008
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Deshpande, Manoj M., Nanda, Sanjiv, Chen, Jen Mei, Pica, Francesco, Agashe, Parag A., Horn, Gavin B., Prakash, Rajat, Tenny, Nathan E., Gholmieh, Aziz, Balasubramanian, Srinivasan, Yavuz, Mehmet
• Primary Examiner(s): Patel, Ajit
• Application Number:
  US12/511,904
• Publication Number:
  US 20100029274A1
• Time in Patent Office: 1,574 Days
• Field of Search: 455/422.1, 455/432.1, 455/434, 370/328, 370/329, 370/341
• US Class Current: 455/434
• CPC Class Codes: H04J 11/0093 Neighbour cell search
• CPC Class Codes: H04W 48/16 Discovering, processing access restriction or access information
• CPC Class Codes: H04W 48/20 Selecting an access point
• CPC Class Codes: Y02D 30/70 in wireless communication networks

Abstract

Systems and methodologies are described herein that facilitate improved cell search and selection in a wireless communication system. For example, a terminal as described herein can utilize one or more Closed Subscriber Group (CSG)-specific offset and/or hysteresis parameters as described herein to increase the amount of time on which the terminal is allowed to camp on a desirable cell. Additionally, specialized reselection timing can be employed as described herein to increase a delay associated with selecting a Home Node B (HNB) or Home Evolved Node B (HeNB) cell, thereby reducing power consumption associated with rapid cell reselection operations in a densely populated network environment. Further, a two-step reselection process can be performed as described herein in the context of selecting a frequency for cell reselection, thereby mitigating the effects of rapid reselection between cells and/or frequencies due to CSG cell prioritization.

Claims

1. A method, comprising:

identifying a ranking criterion associated with selection of a cell in a wireless communication system;

determining whether the cell is known to belong to an associated Closed Subscriber Group (CSG) whitelist; and

selecting at least one of an offset or a hysteresis parameter to be applied to the ranking criterion based at least in part on a result of the determining, wherein a first ranking offset or hysteresis parameter is selected upon determining that the cell is known to belong to the associated CSG whitelist, and a second ranking offset or hysteresis parameter is selected upon determining that the cell is not known to belong to the associated CSG whitelist.

2. The method of claim 1, wherein the cell is a candidate cell for reselection in an idle mode.

3. The method of claim 2, wherein the determining comprises:

determining whether the candidate cell is a Home Node B (HNB) or a Home Evolved Node B (HeNB); and

determining that the candidate cell is not known to belong to the associated CSG whitelist upon determining that the candidate cell is not a HNB or a HeNB.

4. The method of claim 1, wherein the determining comprises:

receiving a set of identifier values reserved for CSG cells;

attempting to match an identifier value corresponding to the cell to an identifier value in the set of identifier values; and

upon successful matching of the identifier value corresponding to the cell to an identifier value in the set of identifier values, determining whether the cell is known to belong to the associated CSG whitelist at least in part by reading a CSG identifier (ID) of the cell.

5. The method of claim 1, wherein the determining comprises:

obtaining a fingerprint signal pattern corresponding to a current location;

determining whether the fingerprint signal pattern indicates one or more cells belonging to the associated CSG whitelist; and

upon determining that the fingerprint signal pattern indicates one or more cells belonging to the associated CSG whitelist, reading CSG IDs of respective cells within a predefined range and determining whether the respective cells are known to belong to the associated CSG whitelist based at least in part on the respective CSG IDs.

6. The method of claim 1, wherein the cell is a currently camped cell.

7. The method of claim 1, wherein the selecting comprises selecting a positive ranking offset or hysteresis parameter upon determining that the cell is known to belong to the associated CSG whitelist, thereby increasing a distance from the cell at which reselection to the cell from a disparate cell or reselection from the cell to a disparate cell occurs.

8. The method of claim 1, wherein the selecting comprises selecting a negative ranking offset or hysteresis parameter upon determining that the cell is not known to belong to the associated CSG whitelist, thereby decreasing a distance from the cell at which reselection to the cell from a disparate cell or reselection from the cell to a disparate cell occurs.

9. The method of claim 1, wherein the selecting comprises:

determining whether one or more CSG-specific offsets are available;

selecting a CSG-specific offset upon determining that one or more CSG-specific offsets are available; and

selecting a system-wide offset upon determining that one or more CSG-specific offsets are not available.

33. The method of claim 1, wherein the first ranking offset or hysteresis is a positive ranking offset or hysteresis, and the second ranking offset or hysteresis is a negative ranking offset or hysteresis.

10. A wireless communications apparatus, comprising:

a memory that stores data relating to a network cell, a ranking metric associated with selection of the network cell, and a list of allowed Closed Subscriber Group (CSG) cells; and

a processor configured to select at least one of an offset or a hysteresis parameter to be applied to the ranking metric associated with selection of the network cell based at least in part on a result of a determination of whether the network cell is known to belong to the list of allowed CSG cells, wherein a first ranking offset or hysteresis parameter is selected upon determining that the cell is known to belong to the associated CSG whitelist, and a second ranking offset or hysteresis parameter is selected upon determining that the cell is not known to belong to the associated CSG whitelist.

11. The wireless communications apparatus of claim 10, wherein the network cell is a candidate cell for reselection in an idle mode.

12. The wireless communications apparatus of claim 10, wherein the processor is further configured to determine whether the network cell is a Home Node B (HNB) or a Home Evolved Node B (HeNB) and to determine that the candidate cell is not known to belong to the list of allowed CSG cells upon determining that the candidate cell is not a HNB or a HeNB.

13. The wireless communications apparatus of claim 10, wherein:

the memory further stores data relating to identifier values reserved for respective CSG cells; and

the processor is further configured to attempt matching of an identifier value corresponding to the network cell to an identifier value reserved for a CSG cell stored by the memory and, upon a successful attempt, to determine whether the network cell is known to belong to the list of allowed CSG cells at least in part by reading a CSG identifier (ID) of the network cell.

14. The wireless communications apparatus of claim 10, wherein the processor is further configured to obtain a fingerprint signal pattern corresponding to a current location, to determine whether the fingerprint signal pattern indicates one or more allowed CSG cells within a predefined range of the current location, and, upon determining that the fingerprint signal pattern indicates one or more allowed CSG cells within a predefined range of the current location, to determine whether the network cell is known to belong to the list of allowed CSG cells at least in part by reading a CSG identifier (ID) of the network cell.

15. The wireless communications apparatus of claim 10, wherein the cell is a currently camped cell.

16. The wireless communications apparatus of claim 10, wherein the processor is further configured to select a positive ranking offset or hysteresis parameter upon determining that the network cell is known to belong to the list of allowed CSG cells, thereby increasing a distance from the network cell at which reselection to the network cell from a disparate cell or reselection from the network cell to a disparate cell occurs.

17. The wireless communications apparatus of claim 10, wherein the processor is further configured to select a negative ranking offset or hysteresis parameter upon determining that the network cell is not known to belong to the list of allowed CSG cells, thereby decreasing a distance from the network cell at which reselection to the network cell from a disparate cell or reselection from the network cell to a disparate cell occurs.

18. The wireless communications apparatus of claim 10, wherein the processor is further configured to determine whether one or more CSG-specific offsets are available and to select a CSG-specific offset upon determining that one or more CSG-specific offsets are available or a system-wide offset upon determining that one or more CSG-specific offsets are not available.

34. The wireless communications apparatus of claim 10, wherein the first ranking offset or hysteresis is a positive ranking offset or hysteresis, and the second ranking offset or hysteresis is a negative ranking offset or hysteresis.

19. An apparatus, comprising:

means for identifying a ranking parameter associated with selection of a network cell; and

means for selecting an offset or hysteresis parameter to apply to the ranking parameter for a given network cell based at least in part on a determination of Closed Subscriber Group (CSG) whitelist membership of the given network cell, wherein a first ranking offset or hysteresis parameter is selected upon determining that the cell is known to belong to the associated CSG whitelist, and a second ranking offset or hysteresis parameter is selected upon determining that the cell is not known to belong to the associated CSG whitelist.

20. The apparatus of claim 19, wherein the means for selecting comprises:

means for determining whether the given network cell is a Home Node B (HNB) cell or a Home Evolved Node B (HeNB) cell; and

means for determining that the given network cell is not known to belong to an associated CSG whitelist upon determining that the given network cell is not a HNB cell or a HeNB cell.

21. The apparatus of claim 19, wherein the means for selecting comprises:

means for receiving a set of identifier values reserved for respective CSG cells;

means for attempting to match an identifier value corresponding to the given network cell to an identifier value in the set of identifier values; and

means for determining whether the given network cell is known to belong to an associated CSG whitelist upon successful matching of the identifier value corresponding to the given network cell to an identifier value in the set of identifier values at least in part by reading a CSG identifier of the given network cell.

22. The apparatus of claim 19, wherein the means for selecting comprises:

means for obtaining a fingerprint signal pattern corresponding to a current location;

means for determining whether the fingerprint signal pattern indicates one or more network cells belonging to an associated CSG whitelist within a predefined range; and

means for determining whether respective cells within the predefined range are known to belong to the associated CSG whitelist at least in part by reading CSG identifiers of the respective cells upon determining that the fingerprint signal pattern indicates one or more cells belonging to the associated CSG whitelist.

23. The apparatus of claim 19, wherein the means for selecting comprises means for selecting a positive ranking offset or hysteresis parameter for a given network cell with known CSG whitelist membership, thereby increasing a distance from the network cell at which reselection to the network cell from a disparate cell or reselection from the network cell to a disparate cell occurs.

24. The apparatus of claim 19, wherein the means for selecting comprises means for selecting a negative ranking offset or hysteresis parameter for a given network cell not known to have CSG whitelist membership, thereby decreasing a distance from the network cell at which reselection to the network cell from a disparate cell or reselection from the network cell to a disparate cell occurs.

25. The apparatus of claim 19, wherein the means for selecting comprises:

means for determining whether one or more CSG-specific offsets are available;

means for selecting a CSG-specific offset upon determining that one or more CSG-specific offsets are available; and

means for selecting a system-wide offset upon determining that one or more CSG-specific offsets are not available.

26. A computer program product, comprising:

a non-transitory computer-readable medium, comprising;

code for causing a computer to identify a ranking criterion associated with selection of a cell in a wireless communication system; and

code for causing a computer to select an offset or hysteresis parameter to apply to the ranking criterion associated with selection of the cell based at least in part on a determination of Closed Subscriber Group (CSG) whitelist membership of the cell, wherein a first ranking offset or hysteresis parameter is selected upon determining that the cell is known to belong to the associated CSG whitelist, and a second ranking offset or hysteresis parameter is selected upon determining that the cell is not known to belong to the associated CSG whitelist.

27. The computer program product of claim 26, wherein the code for causing a computer to select comprises:

code for causing a computer to determine whether the cell is a Home Node B (HNB) cell or a Home Evolved Node B (HeNB) cell; and

code for causing a computer to determine that the cell is not known to belong to an associated CSG whitelist upon determining that the cell is not a HNB cell or a HeNB cell.

28. The computer program product of claim 26, wherein the code for causing a computer to select comprises:

code for causing a computer to identify a set of identifier values reserved for respective CSG cells;

code for causing a computer to attempt matching of an identifier value for the cell to an identifier value in the set of identifier values; and

code for causing a computer, upon successful matching of the identifier value for the cell to an identifier value in the set of identifier values, to determine whether the cell is known to belong to an associated CSG whitelist upon at least in part by reading a CSG identifier of the cell.

29. The computer program product of claim 26, wherein the code for causing a computer to select comprises:

code for causing a computer to obtain a fingerprint signal pattern corresponding to a current location;

code for causing a computer to determine whether the fingerprint signal pattern indicates one or more network cells belonging to an associated CSG whitelist within a predefined range; and

code for causing a computer, upon determining that the fingerprint signal pattern indicates one or more cells belonging to the associated CSG whitelist within the predefined range, to determine whether the respective cells are known to belong to the associated CSG whitelist at least in part by reading CSG identifiers of the respective cells.

30. The computer program product of claim 26, wherein the code for causing a computer to select comprises code for causing a computer to select a positive ranking offset or hysteresis parameter for a cell with known CSG whitelist membership, thereby increasing a distance from the cell at which reselection to the cell from a disparate cell or reselection from the cell to a disparate cell occurs.

31. The computer program product of claim 26, wherein the code for causing a computer to select comprises code for causing a computer to select a negative ranking offset or hysteresis parameter for a cell not known to have CSG whitelist membership, thereby decreasing a distance from the cell at which reselection to the cell from a disparate cell or reselection from the cell to a disparate cell occurs.

32. The computer program product of claim 26, wherein the code for causing a computer to select comprises:

code for causing a computer to determine whether one or more CSG-specific offsets are available; and

code for causing a computer to select a CSG-specific offset upon determining that one or more CSG-specific offsets are available or a system-wide offset upon determining that one or more CSG-specific offsets are not available.