Multiplex communications – Communication over free space – Having a plurality of contiguous regions served by...
Reexamination Certificate
1998-01-14
2001-03-27
Vincent, David R. (Department: 2732)
Multiplex communications
Communication over free space
Having a plurality of contiguous regions served by...
C455S432300, C455S435100
Reexamination Certificate
active
06208628
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a method for providing a unique identification of a mobile station, especially during an initial procedure for initiating and re-establishing a link between a mobile station and the associated serving GPRS (General Packet Radio Service) support node (SGSN).
BACKGROUND OF THE INVENTION
GPRS (General Packet Radio Service) that is currently being specified by ETSI (The European Telecommunication Standards Institute) as a service for GSM phase 2+, provides packet switched connections throughout the PLMN (Public Land Mobile Network). The packet switching is performed between the nodes in the network and on the radio interface. Packet traffic may exist between external data networks and mobile stations and between mobile stations. As in other mobile telephone systems, the mobile stations have radio access to the system with a minimum of consideration of how networks are built and which operators that owns them. They may be connected to an operator anywhere in the home country or somewhere abroad and switch country or operator according to their own needs or decisions.
To provide an efficient transfer of packets between the end users (payload) and also for control signalling between the network elements in the PLMN and the mobile station, layered protocols are used. Each layer or control function has its dedicated functions. Identification of a particular subscriber, either for transfer of payload or for control signalling, is normally done by an identification element that e.g. is a part of the header field in each packet or the first packet in case of segmented packets.
The architecture of GPRS is shown in FIG.
1
.
The protocol stack for GPRS is sketched in FIG.
2
.
STATE OF THE ART
The specification for GPRS (attached ETSI spec 03.60 rev 0.20.0) indicates that when a mobile station makes itself available to the PLMN as a result of an automatic or a manual procedure (an attach procedure), the old TLLI (Temporary Logical Link Identifier) will be used as identifier on the radio interface for initial signalling procedures and in the SGSN in order to identify the mobile station and connect it to the IMSI (International Mobile Station Identity), the subscribers unique identity within GSM. When the unique identity is found, information related to the subscription can be found and it can be verified that the mobile station in question is not a fraud. In case this attach procedure is performed in the coverage area of another SGSN than the one where the mobile station performed the last detach procedure, the old TLLI and the old RA (Routing Area) is used to identify the former SGSN in order to fetch the IMSI.
Further, in the specifications, it is indicated that if the system discovers better conditions on cells belonging to a different SGSN than the one where a logical link exists (an inter SGSN routing update procedure), the old TLLI and the old RA will be used as identifiers on the radio interface for initial signalling and to identify the former SGSN in order to find the subscriber's identity (IMSI).
When a mobile station is identified, authentication is performed and relevant subscription data is signalled to the SGSN, a new TLLI is assigned to the mobile station. This TLLI is then used for further signalling within the coverage area of the SGSN. If an attach procedure is initiated within the same SGSN service area as the one where the mobile station performed detach, a change of TLLI is not necessary if the old TLLI is sufficient to identify the mobile station.
The RA is a logical part of the coverage area of an SGSN. According to the specifications, the TLLI can never be uniquely identified in a larger service area than an SGSN.
To use the IMSI as an identifier in this initial procedure is only a recommended solution if other identities cannot be used. This is in order to ensure the largest possible user confidentiality.
PROBLEMS RELATED TO PRIOR ART
As mobile stations may register to the system at unpredictable points, move around within or across country borders or change operator at will, unique identification of a subscriber within the GSM system is necessary in order to provide international roaming. This is not possible by using old TLLI or old TLLI in combination with old RA. This combination will only be able to uniquely identify subscribers within the coverage area of its home PLMN.
OBJECTS OF THE INVENTION
The main object of the present invention is to provide a unique temporary identification for mobile stations in GPRS.
Another object of the invention is to provide a unique identification of a mobile station during the initial procedures to initiate (attach procedure) or to re-establish a link (inter routing area update procedure) between a mobile station and the associated SGSN.
SUMMARY OF THE INVENTION
The above objects are achieved in a method as stated in the preamble, which according to the present invention is characterized by forming a new identity comprising the old temporary logical link identifier (TLLI), the old routing area (RA), an identification of the public land mobile network (PLMN) that is the owner of the old TLLI and the country where the PLMN belong, the new identity being used as identification on the radio interface.
More specifically this unique new identity can be used as an international link set-up identity (ILSI).
Further features and advantages related to the present invention will appear from the following description taken in connection with the attached drawings, as well as from the appending patent claims.
REFERENCES:
patent: 5375251 (1994-12-01), Pfundstein
patent: 5675628 (1997-10-01), Hokkanen
patent: 5873034 (1999-02-01), Alperovich et al.
patent: 5920814 (1999-07-01), Sawyer et al.
patent: 6006094 (1999-12-01), Lee
patent: 0530010 (1993-03-01), None
patent: 0711088 (1996-05-01), None
patent: 94/19891 (1994-09-01), None
patent: 96/04759 (1996-02-01), None
patent: 96/21983 (1996-07-01), None
ETSI: “European Digital Cellular Telecommunications System (Phase 2); Mobile Application Part (MAP) Specification”, GSM 09.02 Dec. 1995.
ETSI: “Release Note—Recommendation GSM 03.12—Location Registration Procedures”, Feb. 1992.
Gangsøy Ole Jonny
Monrad Atle
Burns Doane Swecker & Mathis L.L.P.
Telefonaktiebolaget LM Ericsson (publ)
Vincent David R.
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