Telecommunications – Radiotelephone system – Zoned or cellular telephone system
Reexamination Certificate
1999-07-28
2002-06-04
Vo, Nguyen T. (Department: 2682)
Telecommunications
Radiotelephone system
Zoned or cellular telephone system
C455S560000, C455S433000
Reexamination Certificate
active
06400950
ABSTRACT:
BACKGROUND OF THE PRESENT INVENTION
1. Field of the Invention
The present invention relates generally to telecommunications systems and methods for implementing a cellular system within an H.323 system, and specifically to providing efficient de-registration of multiple mobile stations utilizing H.323 protocols.
2. Background and Objects of the Present Invention
Local Area Networks (LANS) not only interconnect computers for data communications, but can also interconnect terminals or endpoints for voice communications. For example, many LANs are now implementing H.323 architecture to provide multimedia communications services over LANs. H.323 entities may be integrated into personal computers or implemented in stand-alone devices, such as wireline or wireless endpoints, e.g., video or audio telephones. H.323 entities can provide real-time audio, video and/or data communications capabilities in point-to-point or multipoint conferences.
Within an H.323 system, each H.323 endpoint is registered with a Gatekeeper for the H.323 system. The Gatekeeper stores an Internet Protocol (IP) address for the H.323 endpoint, so that when a connection to that H.323 endpoint is requested, the Gatekeeper will know where to route the connection. If the H.323 endpoint is a Mobile Station (MS), the IP address for the MS being served by an H.323 system typically includes the IP address for a Mobile Switching Center (MSC) serving the MS along with a specific port number for that MS. Therefore, although each MS has a separate subscriber record within the Gatekeeper, each MS has the same IP address, e.g., the IP address of the MSC.
In addition to the routing information, the Gatekeeper stores the permanent subscriber information for the MS and routes calls to and from the MS within the H.323 system. In addition, MSs also have a subscription with a Home Location Register (HLR) within the H.323 system or within a Public Land Mobile Network (PLMN) that is associated with the H.323 system area. Therefore, when a call to an MS originates from outside the H.323 system, a query to the HLR is performed to determine where to route the call. If the MS is registered within the H.323 system, the HLR will provide the address for the MSC serving the MS within the H.323 system.
When an HLR shuts down and restarts, the HLR typically loses all of the stored location information for each mobile subscriber associated with the HLR. Therefore, the HLR must send a RESET message to each MSC within the PLMN that the HLR is associated with. In response to the RESET message, each MSC must remove each mobile subscriber currently registered with that MSC. Therefore, unless those mobile subscribers perform a location update, calls cannot be made or received by them.
If one of those MSCs is within an H.323 system, since the routing information is stored in the Gatekeeper, and not in the MSC, the mobile subscribers must be de-registered from the Gatekeeper by the MSC upon receipt of the RESET message from the HLR. In the current architecture, upon receipt of the RESET message, the MSC sends a separate request for de-registration of each mobile subscriber to the Gatekeeper. For example, the H.323 MSC sends a first de-registration request for a first mobile subscriber to the Gatekeeper. The Gatekeeper subsequently de-registers the first mobile subscriber and acknowledges the de-registration of that first mobile subscriber to the MSC. Thereafter, the MSC sends a second de-registration request for a second mobile subscriber to the Gatekeeper. The Gatekeeper subsequently de-registers the second mobile subscriber and acknowledges the de-registration to the MSC. This process continues until the last mobile subscriber served by the MSC is de-registered with the Gatekeeper. It should be understood that the MSC can send the second de-registration request prior to receiving the acknowledgment of de-registration of the first request. However, each de-registration request must be sent separately. This process is extremely inefficient and slow.
SUMMARY OF THE INVENTION
The present invention is directed to telecommunications systems and methods for de-registering all registered Mobile Stations (MSs) at one time from the Gatekeeper of an H.323 system. In preferred embodiments, after an H.323 system shut down or upon receipt of a RESET message from a Home Location Register (HLR), the H.323 Mobile Switching Center (MSC) sends a single Unregistration Request (URQ) message to the Gatekeeper requesting de-registration of all of the registered MSs served by the MSC. The H.225 protocol for the URQ message is modified to indicate that all MSs associated with the MSC are to be de-registered. Alternatively, the modified URQ message can indicate that a certain group of MSs served by the MSC are to be de-registered.
REFERENCES:
patent: 2001/0001268 (2001-05-01), Menon et al.
patent: WO 00/33518 (2000-06-01), None
ITU-T, H.225.0; Call Signalling Protocols and Media Stream Packetization for Packet-Based Multimedia Communication Systems; Chapter 7.1, H.225.0 Message Definitions; ITU-T Recommendation, Series H: Audiovisual and Multimedia Systems, Infrastructure of Audiovisual Services—Transmission Multiplexing and Synchronization; Sep. 1999; pp. 14-65.
ETSI TS 100 525 V7.1.0 (2000-01); Digital Cellular Telecommunications System (Phase 2+); Restoration procedures (GSM 03.07 version 7.1.0 Release 1998); ETSI Technical Specification; Sophia Antipolis, France; Jan. 2000; pp. 1-21.
ITU-T, H.323; Packet Based Multimedia Communications Systems; ITU-T Recommendation, Series H: Audiovisual and Multimedia Systems, Infrastructure of Audiovisual Services—Systems and Terminal Equipment for Audiovisual Services; Sep. 1999; pp. 1-129.
Herman C.H. Rao, Yi-Bing Lin and Sheng-Lin Cho; iGSM: VoIP Service for Mobile Networks; IEEE Communications Magazine; Apr. 2000; pp. 62-69.
PCT International Search Report dated May 22, 2001.
Mukherjee Subrata
Patel Mahesh
Ericsson Inc.
Jenkens & Gilchrist P.C.
Vo Nguyen T.
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