Seamless handoff across heterogeneous access networks using a handoff controller in a service control point

• US 20060276192A1
• Filed: 05/18/2006
• Published: 12/07/2006
• Est. Priority Date: 05/18/2005
• Status: Active Grant

• Current Assignee: Nytell Software LLC (Intellectual Ventures LLC)
• Original Assignee: Telcordia Licensing Co LLC (Telefonaktiebolaget LM Ericsson)
• Inventors: Sempere, Raquel Morera, Demers, Stephanie, Zhang, Tao, Das, Subir, Dutta, Ashutosh, Lukacs, Donald R., Alfieri, James, Lyles, Bryan J., Shrader, David C.
• Granted Patent: US 7,664,501 B2
• Time in Patent Office: Days
• US Class Current: 455/436
• CPC Class Codes: H04W 36/005 involving radio access media independent information, e.g. MIH [Media independent Hand-off]
• CPC Class Codes: H04W 36/304 due to measured or perceived resources with higher communication quality
• CPC Class Codes: H04W 80/00 Wireless network protocols or protocol adaptations to wireless operation

Abstract

In a telecommunications network in which a mobile handset is capable of communicating in both an IP-domain and a non-IP domain, the handoff of an existing communications session between the mobile handset and a fixed user is facilitated by a handoff controller implemented in a service control point. The handoff controller implements different handoff methods depending on the status of the fixed user and the transition of the mobile user. Additionally 802.21 Media Independent Handover Function in conjunction with SIP is used to facilitate handover between IP and Non-IP points in the system.

Claims

1. A method for using a handoff controller for handing off a communication session of a mobile first user from a first network to a second network wherein the first network is either an IP network or a cellular network and the second network is of the other type and wherein a mobile handset operated by the mobile first user is in communication with a handset operated by a static second user comprising the steps of:

sending a message from the handoff controller to the mobile handset instructing the mobile handset to monitor one or more predetermined characteristics of the air interface between the mobile user and the first network;

sending a message from the mobile handset to the handoff controller when one or more predetermined characteristics have been met;

receiving at the handoff controller information regarding the available connection points in the second network;

determining in the handoff controller the identification of a connection point in the second network;

sending a message from the handoff controller to the mobile handset identifying the connection point in the second network;

establishing a communication session between the mobile user of the mobile handset and the second network;

reconnecting the mobile user of the mobile handset and the fixed user.

2. The method of claim 1 wherein the step of sending a message instructing the mobile handset to monitor the air interface is a SIP SUBSCRIBE message.

3. The method of claim 1 wherein the step of sending the message from the mobile hander to the handoff controller is a SIP NOTIFY message.

4. The method of claim 1 wherein the mobile handset is capable of operating in both the IP network and the cellular network.

5. The method of claim 1 wherein the handoff controller resides in the service control point.

6. The method of claim 1 wherein the step of receiving at the handoff controller information regarding the available connection points further comprises the step of sending an ANSI-41 FACDIR2 message to a target MSC and receiving a facdir2 message in return.

7. The method of claim 2 wherein the SIP SUBSCRIBE message includes 802.21 primitives.

8. The method of claim 3 wherein the SIP NOTIFY message includes 802.21 primitives.

9. The method of claim 1 wherein the step of reconnecting the mobile handset and the fixed user comprises the establishment of an RTP session through the use of SIP INVITE, OK and ACKNOWLEDGE messages.

10. The method of claim 1 wherein the cellular network is a CDMA network.

11. The method of claim 1 wherein the cellular network is a GSM network.

12. The method of claim 1 further comprising the step of maintaining records regarding the time of the transition of the mobile handset from one network to another for billing purposes.

13. The method of using SIP messages embedded with 802.21 primitives in order to collect information and distribute instructions regarding the handoff of a communication session of a mobile handset from a first network to a second network.

14. The method of claim 13 wherein the SIP messages are sent and received from a handoff controller implemented in a service control point wherein the handoff controller uses the information to determine to the identity of a target connection point in the second network.

15. A service control point for controlling call sessions between a first user and a second user of a heterogeneous telecommunications network comprising an IP network and a cellular network wherein the first user is moving from either an IP network or a cellular network to the other type and the second user is statically connected to either the IP network or the cellular network comprising:

a means for sending SIP messages to a mobile handset of the first user requesting the mobile handset to monitor predetermined characteristics of the air interface with the network to which the mobile handset is connected;

a handoff controller for receiving information about various connection points to one or more of the networks and for determining to which connection point to handoff the first user.

16. The service control point of claim 15 wherein the SIP messages are embedded with 802.21 media independent handover primitives.