Fast cell selection in a mobile wireless device

• US 9,020,499 B2
• Filed: 10/29/2012
• Issued: 04/28/2015
• 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
• Primary Examiner(s): Patel, Nimesh
• Application Number:
  US13/663,342
• Publication Number:
  US 20130053093A1
• Time in Patent Office: 911 Days
• Field of Search: 455/426, 455/450, 455/525, 455/63.1, 455/67.13, 370/331, 370/332, 370/333, 375/260
• US Class Current: 455/426.1
• CPC Class Codes: H04W 24/08 Testing, supervising or monitoring using real traffic
• CPC Class Codes: H04W 36/08 Reselecting an access point
• CPC Class Codes: H04W 36/30 by measured or perceived connection quality data
• CPC Class Codes: H04W 36/305 Handover due to radio link failure control signalling for hand-off failure H04W36/0079
• CPC Class Codes: H04W 36/36 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 mobile device, comprising:

a processor;

a wireless interface in data communication with the processor; and

logic in data communication with the processor and the wireless interface, the logic configured to cause the mobile device to;

detect when a first cell, to which the mobile device is connected, does not meet one or more suitability criteria;

locate one or more cells for possible connection with the mobile device;

determine whether a candidate cell of the one or more cells is the first cell; and

when the candidate cell is determined to be the first cell;

evaluate whether the candidate cell satisfies the one or more suitability criteria, wherein the evaluation is performed without reading system information messages to obtain the one or more suitability criteria for the candidate cell; and

connect with the candidate cell when the candidate cell is determined to satisfy the one or more suitability criteria;

when none of the one or more cells is determined to be the first cell;

read one or more system information messages to obtain suitability criteria for the one or more cells; and

evaluate whether a second candidate cell of the one or more cells satisfies corresponding suitability criteria; and

connect with the second candidate cell when the second candidate cell is determined to satisfy the corresponding suitability criteria.

2. The mobile device of claim 1, wherein the one or more suitability criteria comprise at least one of a received power level parameter and a received signal quality parameter.

3. The mobile device of claim 1, wherein:

the one or more suitability criteria are stored in the mobile device prior to the detection; and

the evaluation is based at least in part on the stored one or more suitability criteria.

4. The mobile device of claim 3, wherein the one or more suitability criteria are determined from one or more system information blocks received from the first cell before the mobile device detects the first cell does not meet the one or more suitability criteria.

5. The mobile device of claim 1, wherein the mobile device determines whether a candidate cell of the one or more cells is the first cell based at least in part on an estimation of a geographic location of the mobile device.

6. The mobile device of claim 5, wherein the estimation of the geographic location of the mobile device further comprises an estimation of a geographic location of the first cell.

7. The mobile device of claim 1, wherein each cell of the one or more cells has a unique primary scrambling code (PSC).

8. A method of operating a mobile device, the method comprising:

detecting a connection failure with a first cell;

locating a set of candidate cells for possible association with the mobile device;

determining whether at least one candidate cell of the set of candidate cells is the first cell previously associated with the mobile device;

when the at least one candidate cell is the first cell;

evaluating the first cell using one or more suitability criteria, the evaluation based at least in part on information for the first cell stored in the mobile device prior to the detected connection failure; and

associating with the first cell when the first cell satisfies the one or more suitability criteria; and

when no candidate cells in the set of candidate cells is determined to be the first cell;

receiving suitability criteria for one or more candidate cells in the set of candidate cells;

determining whether an identified candidate cell of the set of candidate cells satisfies the received suitability criteria; and

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

9. The method of claim 8, wherein determining whether at least one candidate cell of the set of candidate cells is the first cell is based at least in part on estimating a locational change of the mobile device.

10. The method of claim 9, wherein the estimation of the locational change of the mobile device is based at least in part on a time elapsed from the detection of the connection failure until locating the set of candidate cells.

11. The method of claim 9, wherein the estimation of the locational change of the mobile device is based at least in part on a rate of displacement of the mobile device.

12. The method of claim 9, wherein the estimation of the locational change of the mobile device is based at least in part on a comparison between an estimated location of the mobile device and an estimated location of the first cell.

13. The method of claim 8, wherein determining whether the identified candidate cell satisfies the one or more suitability criteria comprises at least measuring a received signal quality of the identified candidate cell.

14. The method of claim 8, wherein locating the set of candidate cells comprises at least receiving a radio frequency signal identifying the candidate cell.

15. The method of claim 8, wherein each candidate cell of the set of candidate cells has a unique primary scrambling code (PSC).

16. The method of claim 8, wherein the information for the first cell comprises information associated with one or more system information blocks received from the first cell before the mobile device detects the connection failure with the first cell.

17. A non-transitory computer readable apparatus comprising a plurality of instructions that, when executed by a processor, cause a mobile device to:

detect a connection failure with an associated cell;

locate a set of candidate cells for possible association with the mobile device;

determine whether a candidate cell of the set of candidate cells is the associated cell; and

when the candidate cell is the associated cell;

evaluate the candidate cell using at least one suitability criteria, the evaluation based at least in part on suitability criteria for the associated cell stored in the mobile device prior to the detected connection failure; and

associate the mobile device with the candidate cell when the candidate cell satisfies the at least one suitability criteria,

wherein the evaluation is performed without reading system information messages to obtain the at least one suitability criteria for the candidate cell; and

when no candidate cells in the set of candidate cells is determined to be the associated cell;

receiving suitability criteria for one or more of the candidate cells in the set of candidate cells;

determining whether an identified candidate cell in the set of candidate cells satisfies the received suitability criteria; and

associating the mobile device with the identified candidate cell when the identified candidate cell satisfies the received suitability criteria.

18. The non-transitory computer readable apparatus of claim 17, wherein the determination of whether the candidate cell is the associated cell is based at least in part on an estimated geographical location of the mobile device.

19. The non-transitory computer readable apparatus of claim 17, wherein the suitability criteria for the associated cell is based at least in part on one or more system information messages received from the associated cell before the mobile device detects the connection failure with the associated cell.

20. The non-transitory computer readable apparatus of claim 17, wherein the at least one suitability criteria comprises a parameter relating to a received signal quality.