Searching for neighbor cells within a fixed time duration

• US 20040116110A1
• Filed: 08/27/2003
• Published: 06/17/2004
• Est. Priority Date: 08/27/2002
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Amerga, Messay, Halbhavi, Sudhir
• Granted Patent: US 8,068,834 B2
• Time in Patent Office: Days
• US Class Current: 455/422.1
• CPC Class Codes: H04W 24/00 Supervisory, monitoring or testing arrangements
• CPC Class Codes: H04W 48/16 Discovering, processing access restriction or access information
• CPC Class Codes: H04W 52/0216 using a pre-established activity schedule, e.g. traffic indication frame
• CPC Class Codes: H04W 52/0245 according to signal strength
• CPC Class Codes: Y02D 30/70 in wireless communication networks

Abstract

Techniques for searching neighbor cells within a fixed time duration are disclosed. In one embodiment, cells in a monitored list are ranked. A first subset of the ranked cells are searched during each cycle in a series of cycles, and a subset of the remainder of ranked cells is searched in each cycle, the subset varying from cycle to cycle. In another embodiment, the ranking and searching of a subset of the ranked list of cells is performed when the number of monitored cells is greater than a pre-determined search number. In yet another embodiment, the complete list of monitored cells is searched when the number of monitored cells is less than or equal to a pre-determined search number. In various embodiments, the searching comprises one or more of intra-frequency, inter-frequency, or inter-RAT searching. Various other embodiments are also presented. Benefits include allowing prescribed levels of intra-frequency, inter-frequency and/or inter-RAT search to be performed allowing for improved base station selection and therefore improved performance and system capacity.

Claims

1. An apparatus, comprising:

a searcher for;

detecting a plurality of cells to form a ranked list of monitored cells;

searching each cell from a first list of cells during each of a series of cycles; and

searching each cell from a subset of a second list of cells during each of the series of cycles; and

a processor for;

ranking the list of monitored cells to form a ranked list of monitored cells;

selecting the first list of cells from the ranked list of monitored cells; and

selecting the subset of the second list of cells, the second list of cells comprising the remaining cells from the ranked list of monitored cells not selected in the first list of cells, and the selected subset varying during each cycle.

2. The apparatus of claim 1, wherein:

the processor further;

compares the number of cells in the list of monitored cells to a pre-determined search number; and

wherein;

the ranking, selecting the first list, and selecting the subset of the second list is performed when the number of cells in the monitored list is greater than the pre-determined search number.

3. The apparatus of claim 2, wherein the processor directs the searcher to search each cell in the list of monitored cells when the number of cells in the monitored list is less than or equal to the pre-determined search number.

4. A method of monitoring neighbor cells, comprising:

detecting a plurality of cells to form a list of monitored cells;

ranking the list of monitored cells to form a ranked list of monitored cells;

searching each cell from a first list of cells selected from the ranked list of monitored cells during each of a series of cycles; and

searching each cell from a subset selected from a second list of cells during each of the series of cycles, the second list of cells comprising the remaining cells from the ranked list of monitored cells not selected in the first list of cells, and the selected subset varying during each cycle.

5. The method of claim 4, further comprising:

comparing the number of cells in the list of monitored cells to a pre-determined search number; and

wherein the ranking, searching the first list, and searching the subset of the second list is performed when the number of cells in the monitored list is greater than the pre-determined search number.

6. The method of claim 5, further comprising:

searching each cell in the list of monitored cells when the number of cells in the monitored list is less than or equal to the pre-determined search number.

7. The method of claim 4, wherein each subset selected from the second list is selected in round-robin fashion.

8. The method of claim 4, wherein the cells are ranked in decreasing order of measured signal strength.

9. The method of claim 4, wherein the detecting step is repeated with a minimum frequency according to one or more pre-determined refresh parameters.

10. The method of claim 9, wherein the detecting step comprises one or more search types.

11. The method of claim 10, wherein the detecting step comprises intra-frequency searching.

12. The method of claim 10, wherein the detecting step comprises inter-frequency searching.

13. The method of claim 10, wherein the detecting step comprises inter-radio access technology searching.

14. The method of claim 10, wherein the one or more refresh parameters are associated with the one or more search types.

15. The method of claim 4, wherein the plurality of cells detected comprises intra-frequency cells.

16. The method of claim 4, wherein the plurality of cells detected comprises inter-frequency cells.

17. The method of claim 4, wherein the plurality of cells detected comprises inter-radio access technology cells.

18. Processor readable media operable to perform the following steps:

detecting a plurality of cells to form a list of monitored cells;

ranking the list of monitored cells to form a ranked list of monitored cells;

searching each cell from a first list of cells selected from the ranked list of monitored cells during each of a series of cycles; and

searching each cell from a subset selected from a second list of cells during each of the series of cycles, the second list of cells comprising the remaining cells from the ranked list of monitored cells not selected in the first list of cells, and the selected subset varying during each cycle.