FAST CELL SELECTION IN A MOBILE WIRELESS DEVICE

• US 20110319081A1
• Filed: 11/19/2010
• Published: 12/29/2011
• Est. Priority Date: 06/24/2010
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: DEIVASIGAMANI, Giri Prassad, RAMASAMY, Venkatasubramanian, GARG, Sharad, VASUDEVAN, Srinivasan
• Granted Patent: US 8,301,145 B2
• Time in Patent Office: Days
• US Class Current: 455/436
• CPC Class Codes: H04W 24/08 Testing, supervising or monitoring using real traffic
• CPC Class Codes: H04W 36/0055 Transmission or use of information for re-establishing the radio link
• CPC Class Codes: H04W 36/00833 Handover statistics
• CPC Class Codes: H04W 36/08 Reselecting an access point
• CPC Class Codes: H04W 36/304 due to measured or perceived resources with higher communication quality
• CPC Class Codes: H04W 36/305 Handover due to radio link failure control signalling for hand-off failure H04W36/0079
• CPC Class Codes: H04W 36/324 by mobility data, e.g. speed data
• CPC Class Codes: H04W 36/36 by user or terminal equipment
• CPC Class Codes: H04W 48/20 Selecting an access point
• CPC Class Codes: H04W 64/003 locating network equipment

Abstract

A method and apparatus for fast cell selection by a mobile wireless device. The mobile wireless device detects when a first wireless cell fails a set of stored suitability criteria and searches for and locates a set of candidate wireless cells to associate with. The mobile wireless device measures at least one received signal metric for each candidate wireless cell in the set of candidate wireless cells. When a candidate cell in the set of candidate wireless cells is identically the first wireless cell, the mobile wireless device evaluates the suitability of the candidate wireless cell using the stored set of suitability criteria for the first wireless cell and the measured at least one received signal metric for the candidate wireless cell. The mobile wireless communication device associates with the candidate wireless cell when the candidate wireless cell meets the stored set of suitability criteria.

Claims

1. A method, comprising:

in a mobile wireless communication device,

detecting a first wireless cell in a wireless communication network associated with the mobile wireless communication device fails at least one criterion in a set of suitability criteria stored in the mobile wireless communication device;

searching for and locating a set of candidate wireless cells with which to associate;

measuring at least one received signal metric for each candidate wireless cell in the set of candidate wireless cells;

evaluating suitability of a candidate wireless cell in the set of candidate wireless cells using one or more criteria in the stored set of suitability criteria for the first wireless cell and the measured at least one received signal metric for the candidate wireless cell when the candidate wireless cell is identically the first wireless cell; and

associating the mobile wireless communication device with the candidate wireless cell when the candidate wireless cell satisfies one or more criteria in the stored set of suitability criteria.

2. The method as recited in claim 1, wherein searching for and locating the set of candidate wireless cells includes receiving a radio frequency signal from a radio network subsystem in each candidate wireless cell identifying the candidate wireless cell.

3. The method as recited in claim 2, wherein the received signal metric used to measure each candidate wireless cell is a measure of received signal code power.

4. The method as recited in claim 2, wherein the received signal metric used to measure each candidate wireless cell is a chip energy.

5. The method as recited in claim 1, further comprising:

determining whether the candidate wireless cell is identically the first wireless cell by estimating the candidate wireless cell'"'"'s geographic location and the first wireless cell'"'"'s geographic location.

6. The method as recited in claim 1, further comprising:

determining whether the candidate wireless cell is identically the first wireless cell by estimating changes in geographic position of the mobile wireless communication device.

7. The method as recited in claim 1, further comprising:

when the candidate wireless cell is not identically the first wireless cell

receiving suitability criteria for the set of candidate wireless cells from at least one radio network subsystem in the wireless communication network;

evaluating suitability of the set of candidate wireless cells using one or more of the received suitability criteria; and

associating the mobile wireless communication device with a suitable cell in the set of candidate wireless cells.

8. The method as recited in claim 7, wherein the at least one radio network subsystem in the wireless communication network transmits the suitability criteria using broadcast system information messages.

9. A mobile wireless communication device, the device comprising:

an application processor configured to generate and receive messages;

a transceiver connected to the application processor, the transceiver configured to transmit radio frequency signals to and receive radio frequency signals from a wireless communication network and configured to select a cell in the wireless communication network with which to connect by;

detecting a loss of radio frequency connection between the transceiver in the mobile wireless communication device and a first cell in the wireless communication network;

locating a set of candidate cells in the wireless communication network with which to connect;

determining a subset of located candidate cells that match to cell suitability criteria stored in the mobile wireless communication device;

selecting a cell in the subset of located candidate cells based on measuring cell suitability using the stored cell suitability criteria; and

associating the mobile wireless communication device with the selected cell;

wherein the cell suitability criteria are stored in the mobile wireless communication device prior to detecting the loss of radio frequency connection.

10. The mobile wireless communication device as recited in claim 9, wherein the selected cell with which the mobile wireless communication device associates is identically the first cell.

11. The mobile wireless communication device as recited in claim 9, wherein the transceiver is further configured to select the cell in the wireless communication network with which to connect by:

when none of the cells in the subset of located candidate cells is identically the first cell,

receiving suitability criteria from a radio network subsystem in a located candidate cell in the subset of located candidate cells;

evaluating the located candidate cell'"'"'s suitability using the received suitability criteria; and

associating with the located candidate cell when the located candidate cell satisfies the received suitability criteria.

12. The mobile wireless communication device as recited in claim 11, wherein locating the set of candidate cells in the wireless communication network with which to connect includes receiving a radio frequency signal from the radio network subsystem in each candidate wireless cell identifying the candidate wireless cell.

13. The mobile wireless communication device as recited in claim 11, wherein evaluating the located candidate cell'"'"'s suitability includes measuring a received signal quality of the located candidate cell.

14. The mobile wireless communication device as recited in claim 9, wherein the application processor is configured to determine whether one of the candidate cells is identically the first cell by estimating the one of the candidate cells geographic location and the first cell'"'"'s geographic location.

15. The mobile wireless communication device as recited in claim 9, wherein the application processor is configured to determine whether the selected cell is identically the first cell using a measure of time elapsed after detecting the loss of radio frequency connection between the transceiver and the first cell.

16. The mobile wireless communication device as recited in claim 9 wherein the application processor is configured to determine whether the selected cell is identically the first cell using a measure of a rate of displacement of the mobile wireless communication device.

17. A computer readable medium for storing non-transitory computer program code executable by a processor in a mobile wireless communication device for selecting a cell in a wireless network with which to associate comprising:

in the mobile wireless communication device,

non-transitory computer program code for detecting a first cell fails one or more suitability criteria stored in the mobile wireless communication device;

non-transitory computer program code for searching for and locating a set of candidate cells with which to associate the mobile wireless communication device;

non-transitory computer program code for determining if one of the candidate cells in the set of candidate cells is identically the first cell;

non-transitory computer program code for evaluating suitability of the first cell using the one or more stored suitability criteria when one of the candidate cells is the first cell; and

non-transitory computer program code for associating with the first cell when one of the candidate cells in the set of candidate cells is identically the first cell and the first cell is suitable.

18. The computer readable medium as recited in claim 17 further comprising:

non-transitory computer program code for receiving suitability criteria for the set of candidate cells from the wireless network when the first candidate cell is not the first cell and for evaluating the set of candidate cells'"'"' suitability using the received suitability criteria; and

non-transitory computer program code for associating with a suitable candidate cell.

19. The computer readable medium as recited in claim 17, wherein non-transitory computer program code for locating the set of candidate cells includes receiving a radio frequency signal from the radio network subsystem in each candidate wireless cell identifying the candidate wireless cell.

20. The computer readable medium as recited in claim 18, wherein non-transitory computer program code for receiving suitability criteria for the set of candidate cells from the wireless network includes receiving system information messages broadcast by radio network subsystems in the candidate cells.

21. The computer readable medium as recited in claim 20, wherein non-transitory computer program code for determining whether one if one of the candidate cells in the set of candidate cells is identically the first cell includes receiving master information messages broadcast by radio network subsystems in the candidate cells.

22. The computer readable medium as recited in claim 17, wherein non-transitory computer program code for determining whether the candidate wireless cell is identically the first wireless cell includes estimating changes in geographic position of the mobile wireless communication device.

23. The computer readable medium as recited in claim 17, wherein non-transitory computer program code for determining whether the candidate wireless cell is identically the first wireless cell includes measuring time elapsed after detecting the first cell fails one or more stored suitability criteria.

24. The computer readable medium as recited in claim 18, wherein non-transitory computer program code for determining whether the candidate wireless cell is identically the first wireless cell includes estimating the candidate wireless cell'"'"'s geographic location and the first wireless cell'"'"'s geographic location.