System, method and device for handling voice calls on a dual-mode wireless mobile communication device

• US 8,315,228 B2
• Filed: 05/06/2010
• Issued: 11/20/2012
• Est. Priority Date: 01/25/2010
• Status: Active Grant

• Current Assignee: Malikie Innovations Limited (Key Patent Innovations Limited)
• Original Assignee: Blackberry Limited
• Inventors: George, Richard John, Lim, Miranda Bing Ying, Buzdugan, Marian Constantin
• Primary Examiner(s): Yao, Kwang B
• Assistant Examiner(s): Ngo, Nguyen
• Application Number:
  US12/774,791
• Publication Number:
  US 20110182273A1
• Time in Patent Office: 929 Days
• Field of Search: 370/229, 370/230, 370/310, 370/328, 370/331, 370/332
• US Class Current: 370/331
• CPC Class Codes: H04W 28/18 Negotiating wireless communication parameters
• CPC Class Codes: H04W 36/00837 Determination of triggering parameters for hand-off
• CPC Class Codes: H04W 36/14 Reselecting a network or an air interface
• CPC Class Codes: H04W 36/30 by measured or perceived connection quality data
• CPC Class Codes: H04W 48/16 Discovering, processing access restriction or access information
• CPC Class Codes: H04W 84/12 WLAN [Wireless Local Area Networks]
• CPC Class Codes: H04W 88/06 adapted for operation in multiple networks or having at least two operational modes, e.g. multi-mode terminals

Abstract

To handle a communication session at a wireless mobile communications device, after receiving an indication of current signal strength of an access point for a wireless local area network (“WLAN”) a signal strength threshold associated with the access point is retrieved. If the communication session is currently carried by a cellular network and the current signal strength exceeds the signal strength threshold, the communication session is switched from the cellular network to the WLAN. A metric is then adjusted based on timing of the switch relative to any switch of the communication session from the WLAN to the cellular network over a preceding time window associated with the access point. Based on the metric, the signal strength threshold associated with the access point is selectively adjusted. If, on the other hand, the communication session is currently carried by the WLAN and the current signal strength is below the signal strength threshold, an attempt is made to switch the communication session from the WLAN to the cellular network and a metric associated with the access point is adjusted based on whether or not the switch failed. Based on this second metric, the signal strength threshold associated with said access point is adjusted.

Claims

1. A method of handling a communication session, comprising:

at a wireless mobile communications device;

receiving an indication of current signal strength of an access point for a wireless local area network (“

WLAN”

);

retrieving a signal strength threshold associated with said access point;

if said communication session is currently carried by a cellular network and said current signal strength exceeds said signal strength threshold, switching said communication session from said cellular network to said WLAN;

adjusting a metric based on timing of said switching relative to any switch of said communication session from said WLAN to said cellular network over a preceding time window associated with said access point; and

based on said metric, selectively adjusting said signal strength threshold associated with said access point;

wherein said metric is based on an average switch rate, at said wireless mobile communications device, from said access point of said WLAN to said cellular network within a predefined number of minutes of a switch from said cellular network to said WLAN, within said preceding time window.

2. The method of claim 1, wherein said selectively adjusting said signal strength threshold associated with said access point comprises increasing said signal strength threshold if said metric exceeds a maximum threshold for said metric.

3. The method of claim 2, wherein said selectively adjusting said signal strength threshold associated with said access point further comprises decreasing said signal strength threshold if said metric is below a minimum threshold for said metric.

4. The method of claim 3, wherein said preceding time window is one week;

said predefined number of minutes is one minute;

said maximum threshold for said metric is a thirty percent switch rate on average from said access point of said WLAN to said cellular network within said predefined number of minutes of a switch from said cellular network to said WLAN, within said preceding time window; and

said minimum threshold for said metric is a two percent switch rate on average from said access point of said WLAN to said cellular network within said predefined number of minutes of a switch from said cellular network to said WLAN, within said preceding time window.

5. The method of claim 1, wherein said communication session is a voice call.

6. A method of handling a communication session, comprising:

at a wireless mobile communications device;

receiving an indication of current signal strength of an access point for a wireless local area network (“

WLAN”

);

retrieving a signal strength threshold associated with said access point;

if said communication session is currently carried by said WLAN and said current signal strength is below said signal strength threshold, attempting to switch said communication session from said WLAN to a cellular network;

adjusting a failure rate associated with said access point based on whether said attempting to switch said communication session from said WLAN to said cellular network failed;

where said attempting to switch results in a switch, adjusting a switch rate associated with said access point so that said switch rate reflects the number of switches per minute of said communication session from said WLAN to said cellular network and the number of such switches per minute of previous communication sessions over a preceding time window; and

based on said failure rate and said switch rate, selectively adjusting said signal strength threshold associated with said access point.

7. The method of claim 6, wherein said selectively adjusting said signal strength threshold associated with said access point comprises increasing said signal strength threshold if said metric exceeds a maximum threshold for said metric.

8. The method of claim 7, wherein said selectively adjusting said signal strength threshold associated with said access point further comprises decreasing said signal strength threshold if said metric is below a minimum threshold for said metric.

9. The method of claim 8, wherein said metric is based on an average rate of failed switches, at said wireless mobile communications device, from said access point of said WLAN to said cellular network, within a preceding time window.

10. The method of claim 6, wherein said selectively adjusting said signal strength threshold associated with said access point comprises increasing said signal strength threshold if said failure rate exceeds a first maximum threshold for said failure rate or if said switch rate exceeds a second maximum threshold for said further metric, and decreasing said signal strength threshold if said failure rate is below a first minimum threshold for said failure rate or if said switch rate is below a second minimum threshold for said switch rate.

11. The method of claim 10, wherein said preceding time window is a first preceding time window and said failure rate is based on an average rate of failed switches, at said wireless mobile communications device, from said access point of said WLAN to said cellular network, within a second preceding time window.

12. The method of claim 11, wherein said first preceding time window is one week;

said second preceding time window is one week;

said first maximum threshold for said failure rate is a thirty percent rate of failed switches from said access point of said WLAN to said cellular network within said first preceding time window;

said second maximum threshold for said switch rate is one switch on average from said access point of said WLAN to said cellular network per minute per communication session within said second preceding time window;

said first minimum threshold for said failure rate is a two percent rate of failed switches from said access point of said WLAN to said cellular network within said preceding time window; and

said second minimum threshold for said switch rate is 0.2 switches on average from said access point of said WLAN to said cellular network per minute per communication session within said second preceding time window.

13. The method of claim 6, wherein said communication session is a voice call.

14. A method of handling a communication session, comprising:

at a wireless mobile communications device;

receiving an indication of current signal strength of an access point for a wireless local area network (“

WLAN”

);

retrieving a signal strength threshold associated with said access point;

if said communication session is currently carried by said WLAN and said current signal strength is below said signal strength threshold, attempting to switch said communication session from said WLAN to a cellular network;

adjusting a metric associated with said access point based on whether said attempting to switch said communication session from said WLAN to said cellular network failed;

based on said metric, selectively adjusting said signal strength threshold associated with said access point;

wherein said selectively adjusting said signal strength threshold associated with said access point comprises increasing said signal strength threshold if said metric exceeds a maximum threshold for said metric;

wherein said selectively adjusting said signal strength threshold associated with said access point further comprises decreasing said signal strength threshold if said metric is below a minimum threshold for said metric;

wherein said metric is based on an average rate of failed switches, at said wireless mobile communications device, from said access point of said WLAN to said cellular network, within a preceding time window; and

wherein said preceding time window is one week;

said maximum threshold for said metric is a thirty percent rate of failed switches from said access point of said WLAN to said cellular network within said preceding time window; and

said minimum threshold for said metric is a two percent rate of failed switches from said access point of said WLAN to said cellular network within said preceding time window.

15. A dual mode mobile communication device comprising a memory, a speaker, a microphone, and a processor, said processor configured to:

during a communication session;

receive an indication of current signal strength of an access point for a wireless local area network (“

WLAN”

);

retrieve a signal strength threshold associated with said access point;

if said communication session is currently carried by a cellular network and said current signal strength exceeds said signal strength threshold, attempt to switch said communication session from said cellular network to said WLAN;

adjust a failure rate based on timing of said switching relative to any switch of said communication session from said WLAN to said cellular network over a preceding time window associated with said access point;

where said attempt to switch results in a switch, adjust a switch rate associated with said access point so that said switch rate reflects the number of switches per minute of said communication session from said WLAN to said cellular network and the number of such switches per minute of previous communication sessions over a preceding time window; and

based on said failure rate and said switch rate, selectively adjust said signal strength threshold associated with said access point.

16. A non-transitory computer readable medium containing computer readable instructions which when executed by a processor of a dual mode mobile communication device, cause said processor to:

during a communication session;

receive an indication of current signal strength of an access point for a wireless local area network (“

WLAN”

);

retrieve a signal strength threshold associated with said access point;

if said communication session is currently carried by a cellular network and said current signal strength exceeds said signal strength threshold, attempt to switch said communication session from said cellular network to said WLAN;

adjust a failure rate based on timing of said switching relative to any switch of said communication session from said WLAN to said cellular network over a preceding time window associated with said access point;

where said attempt to switch results in a switch, adjust a switch rate associated with said access point so that said switch rate reflects the number of switches per minute of said communication session from said WLAN to said cellular network and the number of such switches per minute of previous communication sessions over a preceding time window; and

based on said failure rate and said switch rate, selectively adjust said signal strength threshold associated with said access point.