Method and System for Triggering Handoff of a Call Between Networks

A method for handing off a call between networks, comprising:

• monitoring a quality of a first link between a mobile station and a wireless local area network (WLAN) when the mobile station is actively connected with the WLAN on a call;
• monitoring a quality of a second link between the mobile station and a cellular network when the mobile station is actively connected with the WLAN on the call
• triggering a handoff of the call from the WLAN to the cellular network when the quality of the first link is less than a handoff trigger threshold for a drop count duration and when the quality of the second link is greater than a minimum cellular link quality threshold;
• and
• preventing a handoff of the call from the cellular network to the WLAN until expiration of a first amount of time as long as the quality of the second link remains above the minimum cellular link quality threshold.

A system for handing off a call between networks, comprising a mobile station comprising a controller operable to:

• monitor a quality of a first link between the mobile station and a wireless local area network (WLAN) when the mobile station is actively connected with the WLAN on a call;
• monitor a quality of a second link between the mobile station and a cellular network when the mobile station is actively connected with the WLAN on the call;
• trigger a handoff of the call from the WLAN to the cellular network when the quality of the first link is less than a handoff trigger threshold for a drop count duration and when the quality of the second link is greater than a minimum cellular link quality threshold;
• and
• prevent a handoff of the call from the cellular network to the WLAN until expiration of a first amount of time as long as the quality of the second link remains above the minimum cellular link quality threshold.

A system for handing off a call between networks, comprising:

• means for monitoring a quality of a first link between a mobile station and a wireless local area network (WLAN) when the mobile station is actively connected with the WLAN on a call;
• means for monitoring a quality of a second link between the mobile station and a cellular network when the mobile station is actively connected with the WLAN on the call;
• means for triggering a handoff of the call from the WLAN to the cellular network when the quality of the first link is less than a handoff trigger threshold for a drop count duration and when the quality of the second link is greater than a minimum cellular link quality threshold;
• and
• means for preventing a handoff of the call from the cellular network to the WLAN until expiration of a first amount of time as long as the quality of the second link remains above the minimum cellular link quality threshold.

Software embedded in a computer readable medium comprising code operable to:

• monitor a quality of a first link between a mobile station and a wireless local area network (WLAN) when the mobile station is actively connected with the WLAN on a call;
• monitor a quality of a second link between the mobile station and a cellular network when the mobile station is actively connected with the WLAN on the call;
• and
• trigger a handoff of the call from the WLAN to the cellular network when the quality of the first link is less than a handoff trigger threshold for a drop count duration and when the quality of the second link is greater than a minimum cellular link quality threshold.

A method for handing off a call between networks, comprising:

• monitoring a quality of a first link between a mobile station and a cellular network when the mobile station is actively connected with the cellular network on a call;
• monitoring a quality of a second link between the mobile station and a wireless local area network (WLAN) when the mobile station is actively connected with the cellular network on the call;
• triggering a handoff of the call from the cellular network to the WLAN when the quality of the first link is less than a handoff trigger threshold for a drop count duration and when the quality of the second link is greater than a minimum WLAN link quality threshold;
• and
• preventing a handoff of the call from the WLAN to the cellular network until expiration of a first amount of time as long as the quality of the second link remains above the minimum WLAN link quality threshold.