Hand-out and hand-in support for legacy mobiles serviced by a femtocell attached to an IMS network

• US 8,805,370 B1
• Filed: 03/13/2009
• Issued: 08/12/2014
• Est. Priority Date: 06/21/2005
• Status: Active Grant

• Current Assignee: Ribbon Communications Operating Company, Inc. (Ribbon Communications, Inc.)
• Original Assignee: Taqua Wireless LLC (Ribbon Communications, Inc.)
• Inventors: Kannan, Vinod, Kura, Shasidhar
• Primary Examiner(s): Bost, Dwayne
• Assistant Examiner(s): Trandai, Scott
• Application Number:
  US12/404,064
• Time in Patent Office: 1,978 Days
• Field of Search: 370/252, 370/329, 370/337, 370/338, 370/335, 370/353, 370/389, 370/401, 370/436, 455/411, 455/418, 455/466
• US Class Current: 455/436
• CPC Class Codes: H04L 12/6418 Hybrid transport
• CPC Class Codes: H04L 12/66 Arrangements for connecting between networks having differing types of switching systems, e.g. gateways
• CPC Class Codes: H04L 65/1016 IP multimedia subsystem [IMS]
• CPC Class Codes: H04L 65/1073 Registration or de-registration
• CPC Class Codes: H04W 12/08 Access security
• CPC Class Codes: H04W 36/00226 wherein the core network technologies comprise IP multimedia system [IMS], e.g. single radio voice call continuity [SRVCC]
• CPC Class Codes: H04W 84/045 using private Base Stations, e.g. femto Base Stations, home Node B

Abstract

The present disclosure is directed to a system and method configured to implement an inter-MSC based handoff of a mobile device between a packet switched network and a mobile core network. In embodiments implementing a handoff from a femtocell to a macrocell, from the perspective of a neighboring MSC on a mobile core network, IP or VOIP information from a femtocell which is in communication with the convergence server, is perceived as having the same protocol as information which originates from a macrocell. Inversely, in embodiments implementing a hand-in to the femtocell from a macrocell, information which originates from a macrocell, which is in communication with the convergence server, would be perceived as IP or VOIP code to the femtocell. Accordingly, a target MSC in a handoff is agnostic of the fact that the mobile device entering into the macrocell was actually attached to a femtocell. Thus, embodiments of the present invention allow existing inter-MSC based handoff solutions to be leveraged.

Claims

1. A method for handing off a mobile device from a femtocell to a mobile switching center, the method comprising;

responsive to the mobile device identifying that signal strength for base station is higher than signal strength for femtocell, sending, from the mobile device a first handoff request to the femtocell;

responsive to receiving the first handoff request from the mobile device, encapsulating, by the femtocell, information from the handoff request into a handoff request message, and sending the handoff request message to a convergence server;

responsive to receiving the handoff request message, sending to a media server, by the convergence server, a request to assign a new circuit identification;

responsive to receiving the request to assign the new circuit identification, assigning, by the media server the new circuit identification, and conforming the convergence server of new circuit identification;

responsive to receiving the new circuit identification, sending, by the convergence server, routing information for the mobile device to a target mobile switching center;

responsive to receiving routing information for the mobile device, sending, by the target mobile switching center, a second handoff request to a target radio network controller;

responsive to receiving a second handoff request from the target mobile, determining, by the switching center, whether a base station can support the mobile device by obtains information from the base station regarding capacity and availability of the base station;

responsive to determining that the base station can support the mobile device, sending, by the target radio network controller, an acknowledgment message to the target mobile switching center;

responsive to receiving the acknowledgment message at the target mobile switching center, relaying, by the target mobile switching center, the acknowledgment message to the convergence server;

responsive to receiving the acknowledgment message at the convergence server, sending, by the convergence server, a handoff command to the femtocell;

responsive to receiving the handoff command at the femtocell, sending by the femtocell, a response to the convergence server that a handoff has commenced;

initiating, by the convergence server, a dummy traffic channel between the target mobile switching and the target radio network controller;

responsive to establishing a traffic channel, sending, by the target radio network controller, a handoff complete message to the target mobile switching center;

responsive to receiving the handoff complete message from the target radio network controller, sending, by the target mobile switching center, a ready-for-handoff message to the convergence server;

responsive to receiving the ready-for-handoff message, sending, by the convergence server, and update message to the media server informing the media server to bind a new circuit identification to the dummy traffic channel;

responsive to receiving the update message, binding, by the media server, the new circuit identification, and notifying the convergence server that the new circuit identification is bound;

responsive to receiving notification that the new circuit identification is bound, sending, by the convergence server, a clear command to the femtocell; and

responsive to receiving the information, terminating, by the femtocell, a communication path between the mobile device and the femtocell.

2. A method for handing off a mobile device communicating on a first communication path, said method comprising:

receiving a handoff request from an access point hosting said mobile device;

processing said handoff request at a system which arbitrates communications between a packet switched network and a mobile core network, said system configured to relay information on a packet switched network and further configured to appear to components of said mobile core network as being a switching device;

executing an inter-MSC based handoff between said system and an MSC connected to said mobile core network;

establishing a second communication path for said mobile device, said second communication path including a second access point to service said mobile device, said second access configured to communicate on different network type than the network of said first access point, wherein said system utilizes a media server which is in said first communication path to establish said second communication path and keeps said media server in said second communication path after handing off said mobile device; and

handing off said mobile device.

3. The method of claim 2 wherein said system is configured to appear to components of said mobile core network as being a mobile switching center (MSC).

4. The method of claim 2 wherein said system is configured to utilize a media server to establish said second communication path.

5. The method of claim 2 wherein said first access point is a femtocell and said second access point is a base station in a cellular network.

6. The method of claim 2 wherein said first access point is a base station in a cellular network and said second access point is a femtocell.

7. The method of claim 2 wherein said mobile device is a legacy mobile device.

8. The method of claim 2 wherein said system comprises a convergence server.

9. The method of claim 2, wherein said handoff request from said access point was initiated by said mobile device.

10. The method of claim 9, wherein said mobile device initiated the handoff when said mobile device recognized that the handoff was desired.

11. The method of claim 10, wherein said mobile device recognized that the handoff was desired because a first signal strength for a different base station was determined by said mobile device to be higher than a second signal strength of said access point.

12. A system for compensating for differing communication protocols in a packet switched network and a mobile core network, said system comprising:

a convergence server, said convergence server configured to facilitate a handoff of a legacy mobile device between a packet switched network and cellular core network while maintaining an active call, wherein said convergence server is configured to identify and register users entering areas which use different protocols, and wherein said convergence server maintains a database containing both a packet switched network public identity and a mobile core network identity for one or more mobile devices.

13. The system of claim 12 wherein said convergence server obtains information about an packet switched network public identity and an mobile core network identity notifies a home subscriber server (HSS) of such identities.

14. The system of claim 12 wherein said convergence server is configured to be a mobile switching center (MSC) and implement inter-MSC based handoff functionality.

15. The system of claim 14 wherein said convergence server is configured to communicate with a media server using session initiation protocol (SIP).

16. The system of claim 12 wherein said convergence server is configured to manipulate communication trunks of said mobile devices.

17. The system of claim 12 wherein said convergence server does not have a dedicated media server and is configured to utilize a media server that is part of an existing communication path.

18. A method comprising:

receiving, by a system which arbitrates communications between a packet switched network and a mobile core network, a handoff request from an access point hosting a mobile device, said access point connected to one of said packet switched network and said mobile core network;

requesting, by said system, routing circuit information from a media server controller;

communicating, by said system, said routing circuit information with a mobile switching center (MSC);

handing off said mobile device to a second access point using said routing circuit information, said second access point being connected to the other of said packet switched network and said mobile core network.

19. The method of claim 18 further comprising handing off said wireless device from said packet switched network to said mobile core network.

20. The method of claim 19 further comprising handing off said wireless device from said mobile core network to said packet switched network.

21. The method of claim 18 wherein said mobile device is a legacy mobile device.

22. The method of claim 18 wherein said system is a convergence server configured to be a mobile switching center (MSC).