United States Patent (19)
`JOSSe et al.
`
`USOO6104929A
`Patent Number:
`11
`(45) Date of Patent:
`
`6,104,929
`Aug. 15, 2000
`
`54) DATA PACKET RADIO SERVICE WITH
`ENHANCED MOBILITY MANAGEMENT
`
`2 307 828 6/1997 United Kingdom.
`
`OTHER PUBLICATIONS
`
`75 Inventors: Thierry Josse, Stockholm, Sweden;
`REFERE,drid Digital Cellular Telecommunications System (Phase 2+),
`S g
`s
`s
`General Packet Radio Service (GPRS) Service Description,
`p
`TS GSM 03.60 version 2.0.0, May 1997.
`73 ASSignee: Sleathlet LM Ericsson,
`Brasche et al., Analysis of Multi-Slot MAC Protocols Pro
`Stockholm, Sweden
`posed for the GSM Phase 2+ General Packet Radio Service,
`1997 IEEE 47" Vehicular Technology Conference, Phoenix,
`AZ, May 4–7, 1997, vol. 2, No. CONF. 47, May 4, 1997, pp.
`1295-1300.
`
`21 Appl. No.: 09/090,186
`22 Filed:
`Jun. 4, 1998
`
`Related U.S. Application Data
`60 Provisional application No. 60/050,306, Jun. 20, 1997, and E. |ality y Appiah
`provisional application No. 60/050,232, Jul. 11, 1997.
`ssistant Examiner Charles N. Appa
`7
`H04Q 7/20; H04B 1/38
`Attorney, Agent, or Firm Nixon & Vanderhye, P.C.
`51
`Int. Cl. ................................
`52 U.S. Cl. .......................... 455/445; 455/426; 455/560;
`57
`ABSTRACT
`370/379; 370/465
`The address of a latest Serving GPRS Support Node (SGSN)
`58 Field of Search ... 27, 2020 455/426, 445,
`is provided to a Gateway GPRS Support Node (GGSN) by
`455/569; 320328, 329,349; 389, 401,
`a special Update SGSN Address Request message which is
`465, 466; 709/230, 249; 714/748, 749,
`sent from the SGSN to the GGSN. For a Subscriber whose
`750
`subscription permits, the address of the latest SGSN node is
`sent in the Update SGSN Address Request message for a
`qualified packet data protocol (PDP) context. A qualified
`PDP context (1) has a static PDP address; and (2) is not
`activated. The Update SGSN. Address Request message can
`
`References Cited
`U.S. PATENT DOCUMENTS
`
`56)
`
`3. 3/1998 Bill, - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - E. be sent from the SGSN to the GGSN in either a GPRS Attach
`
`- - - S.
`E. E. al.
`s:
`... 370,348
`5.966,37s 10/1999 Hamalainen.
`5.987137 11/1999 Karppanen et al... 360.2s
`FOREIGN PATENT DOCUMENTS
`
`
`
`scenario or an Inter-SGSN Routing Area Update Scenario.
`In response to the Update SGSN Address Request message,
`the GGSN sends an Update SGSNAddress Response mes
`Sage which adviseS whether the updating of the address for
`the SGSN at the GGSN has been Successful.
`
`196 11947
`C1 6/1997 Germany.
`
`24 Claims, 7 Drawing Sheets
`
`Bss
`Ms
`Rotting Area
`Update Request
`
`4-
`4-2a
`4-2b
`
`Security Functions
`
`4-2
`4-3
`4-4a
`4-4.
`4-5a
`4-5b
`
`4-5
`4-5d
`4-5e
`
`newsgs
`
`cases
`
`GGSN
`
`HLR
`
`MSCFVR
`
`-
`
`SGSN Context Request
`SGSN Context Response
`
`Forward Packets
`---a
`update PDP Context Request
`Update PDP Context Response
`Update Location
`Carcelocation
`
`Cancel Location Ack
`insert Subscribe Data
`insert Subscribe Data Ack
`
`4-5
`4-6
`4-7
`4-8a
`4-8b.
`Routing Area Update Accept
`4-9
`4-0 Routing Areaupdate Complete
`
`Update Location Ack
`Update SGSNAddress Request
`Update SGs Address Response
`Location Updating Request
`location Updating Accept
`
`inter SGSNRouting Area Update Procedure
`
`Petitioner's Exhibit 1003
`Page 1 of 17
`
`

`

`U.S. Patent
`
`Aug. 15, 2000
`
`Sheet 1 of 7
`
`6,104,929
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`Petitioner's Exhibit 1003
`Page 2 of 17
`
`

`

`US. Patent
`
`Aug. 15, 2000
`
`Sheet 2 0f 7
`
`6,104,929
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`Petitioner's Exhibit 1003
`
`Page 3 of 17
`
`Petitioner's Exhibit 1003
`Page 3 of 17
`
`
`
`
`
`
`

`

`U.S. Patent
`
`Aug. 15, 2000
`
`Sheet 3 of 7
`
`6,104,929
`
`MS
`BSS
`SGSN
`ATTAC REQUEST
`3-1
`-->
`2 - ->
`32
`
`3-3
`
`GGSN, MSC/VLR
`
`HLR
`
`UPATE LOCATION
`---O-
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`3-4
`op le--ol
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`N
`UPDATE LOCATION ACK
`!----
`UPDATE SGSN ADDRESS REQUEST
`UPDATE SGSNAPDRESS RFPONSE
`-
`
`3-5
`3-6
`3-7
`
`3-8
`
`so
`
`COMBINED IMS/GPRSATTACH PROCEDURE
`
`FIG 3
`
`Petitioner's Exhibit 1003
`Page 4 of 17
`
`

`

`U.S. Patent
`
`Aug. 15, 2000
`
`Sheet 4 of 7
`
`6,104,929
`
`
`
`
`
`old SGSN
`
`GGSN
`
`MSC/WLR
`eW
`
`MSC/WLR
`old
`
`Identification Request
`-->
`ldentification Response
`
`-d- -
`
`---------- -
`
`a
`
`- - - -
`
`any request
`identity Request
`Identity Response
`Authentiation
`ME Check
`
`--a - --
`
`
`
`
`
`
`
`
`
`3-8b.
`3-8C
`3-80
`3-8e
`3-8f
`
`3-9
`
`3-10
`3-1
`
`
`
`
`
`Updatebcation
`Cancel Location
`cancel Lication Ack
`Insert SubsCriber Data
`Insert SubSCriber Data Ack wo
`Update Location Ack
`- - - - - - - - - - - - - - -
`Update SGSNAddress Request
`Update SGSNAddress Respons
`Location Updating Request
`
`- - - - -
`
`- - - --
`
`Update Location
`Cancel Logation --
`Cancel Location Ack
`insertsuite Dat
`Insert Subscriber Data Ack
`-
`- -
`Update Location Ack
`
`Attach ACCept
`Attach Complete
`
`- H -a -um-
`
`
`
`-
`
`Location Updating Accept
`
`TMSlReallocation Complete
`
`Combined MSI/GPRS Attach Procedure
`
`FIG 3A
`
`Petitioner's Exhibit 1003
`Page 5 of 17
`
`

`

`U.S. Patent
`
`Aug. 15, 2000
`
`Sheet 5 of 7
`
`6,104,929
`
`SGSN
`BSS
`MS
`ROUTING AREA UPDATE
`RERUEST
`
`4-1
`
`4-2
`
`d
`
`O
`
`GGSN MSC/VR
`
`HLR
`
`4-3
`
`4-4
`
`4-5
`
`4-6
`
`4-9
`
`4-10
`
`4-11
`
`--->
`DP CONTEKT OPERATIPN
`--->
`
`LOCATIdniSDLOCATION UPDATING
`UPATE SGSNDDRESS REQUEST
`->
`UPDATE SGSN ADDRESS RESPONSE d
`
`ROUTING AREA UPDATE ACCEPT
`---
`
`ROUTING AREAUPDATE COMPLETE
`
`INTER-SGSN ROUTING AREA UPDATE
`PROCEDURE
`
`FIG 4
`
`Petitioner's Exhibit 1003
`Page 6 of 17
`
`

`

`4-1
`4-2a
`4-2b
`
`4-2C
`
`MS T HLR MSCNLR
`
`SGSN Context Reque
`st
`SGSN Context Response
`Forward Packets
`
`U.S. Patent
`
`Aug. 15, 2000
`
`Sheet 6 of 7
`
`6,104,929
`
`FIG 4A
`
`Routing Area
`Update Request
`
`
`------
`
`4-3
`
`
`
`Update PDP Context Request
`------>
`Update PDP Context Response
`Update Location
`
`4-6
`4-7
`4-8a
`
`Update Location Ack
`Update SGSNAddress Request
`Update SGSN. Address Response
`Location Updating Reques
`Location Updating Accept
`
`4-9
`Routing Area Update Accept
`4-10 Routing Area update Complete
`
`
`
`- areas em.
`
`He
`
`rum
`
`un-run - m
`
`Inter SGSN Routing Area Update Procedure
`
`Petitioner's Exhibit 1003
`Page 7 of 17
`
`

`

`U.S. Patent
`US. Patent
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`uA
`Aug. 15, 2000
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`Petitioner's Exhibit 1003
`
`Page 8 of 17
`
`Petitioner's Exhibit 1003
`Page 8 of 17
`
`
`
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`
`
`
`
`

`

`1
`DATA PACKET RADIO SERVICE WITH
`ENHANCED MOBILITY MANAGEMENT
`
`6,104,929
`
`2
`connected. For connecting to connection-oriented, circuit
`Switched networks such as PSTN and/or ISDN, the control
`node can be a mobile Switching center (MSC), which often
`is associated with a visiting location register (VLR). For
`connecting to the general packet radio Services (GPRS) Such
`as Internet (for example), the control node can be a gateway
`GPRS Support node (GGSN). In a GPRS system, there also
`may be one or more Serving GPRS Support Nodes (SGSN).
`The SGSN is the node that serves the mobile station, e.g., the
`node which performs mobility management context at
`GPRS attachment and establishment of PDP context at PDP
`context activation. Importantly, the address of the SGSN
`node currently serving a GPRS-utilizing mobile station must
`be known by the GGSN in order for data packets to be routed
`between the data packet networks and the mobile Station.
`An owner of a mobile Station typically enters into a
`contract or Subscription agreement with a Service provider
`(e.g., a company which operates the telecommunications
`network through which the mobile Station engages in tele
`communications connections). As part of the Subscription
`agreement, the mobile Station is categorized as belonging to
`one of Several acceSS classes available on the network.
`Subscription data from the Subscription agreement is Stored
`in a record maintained e.g., in a home location register
`(HLR) for the mobile station.
`A mobile subscriber who is roaming moves freely within
`the network, with the network knowing where the mobile
`station is located. This makes it possible for the mobile
`Subscriber to receive a call regardless of location. To keep
`the network up to date with the subscriber location, the
`mobile Station informs the System whenever it changes
`location area. This is called location updating.
`One type of location updating is known as an “attach'. An
`IMSI attach is used by the mobile station to notify the
`System that it is in active mode again, provided that it is in
`the same location area as it was when it entered the inactive
`State.
`One prior art attach implementation is the GSM attach
`procedure described Digital Cellular Telecommunications
`System (Phase 2+), General Packet Radio Service (GPRS)
`Service Description, TS GSM 03.60 version 2.0.0, the
`entirety which is explicitly incorporated herein by reference,
`including Section 6.5 thereof.
`Generally, in the GSM attach procedure, a mobile station
`having GPRS capability Sends an Attach Request message to
`a SGSN node. The SGSN node performs identification,
`authentication, and IMEI operations. The SGSN node then
`Sends an Update Location message to the home location
`register (HLR) of the mobile station. The HLR performs
`cancel location procedures, and thereafter performs Insert
`Subscriber Data procedures with respect to the mobile
`Station. In So doing, the HLR sends certain Subscriber data
`for the mobile station to the SGSN. The SGSN, upon
`receiving the subscriber data from the HLR, returns an
`Update Ack message as an acknowledgment. Thereafter,
`location updating procedures are performed, followed by
`transmission of an Attach Accept message from the SGSN to
`the mobile station.
`It is reiterated that the address of the SGSN node currently
`serving a GPRS-utilizing mobile station must be known by
`the Gateway GPRS Support Node (GGSN) in order for data
`packets to be routed between the data packet networks and
`the mobile station. In the prior art, the Gateway GPRS
`Support Node is informed of the address of the latest Serving
`GPRS Support Node only (1) when Packet Data Protocol
`Context activation is performed, or (2) when there is an
`inter-SGSN routing update.
`
`This application claims the benefit and priority of the
`following United States Provisional patent applications,
`both of which are entitled “DATA PACKET RADIO SER
`VICE WITH ENHANCED MOBILITY MANAGEMENT
`and are incorporated herein by reference: U.S. Provisional
`patent application Ser. No. 60/050,306, filed Jun. 20, 1997;
`U.S. Provisional patent application Ser. No. 60/052,232,
`filed Jul 11, 1997.
`FIELD OF THE INVENTION
`The present invention relates to packetized data transmis
`Sions over a radio network, and more particularly, to routing
`of packets to the proper mobile Switch currently Serving a
`mobile radio.
`RELATED ARTAND OTHER
`CONSIDERATIONS
`In recent years cellular telephones have become increas
`ingly popular. A cellular telephone is just one example of
`what is referred to in telephone parlance as a “mobile
`station” or “mobile terminal'. A mobile station can take on
`various forms other than a cellular telephone, including a
`computer (e.g., a laptop computer) with mobile termination
`capabilities. Each Subscriber having a mobile Station is
`assigned a unique International Mobile Subscriber Identity
`(IMSI).
`Telecommunications Services are provided between a
`cellular telecommunications network and a mobile Station
`over an air interface, e.g., over radio frequencies. At any
`moment an active mobile Station is in communication over
`the air interface with one or more base stations (BSs). The
`base Stations are, in turn, managed by base Station control
`lers (BSCs), also known as radio network controllers
`(RNCs). A base station controller (BSC) together with its
`base stations (BSS) comprise a base station system (BSS).
`The base station controllers (BSC) of a base station system
`(BSS) is connected via control nodes to a core telecommu
`nications network.
`One type of Standardized mobile telecommunications
`Scheme, utilized, e.g., in Europe, is the Global System for
`Mobile communications (GSM). GSM includes standards
`which Specify functions and interfaces for various types of
`Services. A relatively recent data Service available within the
`GSM system is General Packet Radio Service (GPRS).
`GPRS differs is from existing data services in that GPRS is
`a packet Switched Service instead of a circuit Switched data
`service. Whereas (in GSM) a circuit Switched data user is
`connected continuously to the radio network during a data
`call (e.g., even when not transferring data), a GPRS user is
`connected to the radio network only when either (1) the
`mobile Station desires to transmit or (2) the network has
`Something to transmit to the mobile Station. In other words,
`in GPRS the mobile station (e.g., a computer with mobile
`termination) is not connected to the network constantly
`while the computer is in use, but only during these two
`transmission events. Examples of GPRS systems are shown
`in U.S. patent application Ser. No. 09/069,969 filed Apr. 30,
`1998 entitled “Dynamic Allocation of Packet Data
`Channels,” and U.S. patent application Ser. No. 09/069,939
`filed Apr. 30, 1998 entitled “Allocation of Channels for
`Packet Data Services,” both of which are incorporated
`herein by reference.
`Control nodes can take various forms, depending on the
`types of Services or networks to which the control nodes are
`
`15
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`Petitioner's Exhibit 1003
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`3
`The prior art occasions for informing the Gateway GPRS
`Support Node (GGSN) of the address of the latest Serving
`GPRS Support Node (SGSN) do not cater to all uses of the
`mobile station. In this regard, a PDP Context activation
`procedure is performed by the mobile Station only in order
`to be able to send/receive Packet Switched information.
`Thus, the prior art does not provide the end-user with the
`ability to receive data packets until this PDP Context acti
`vation procedure is performed due to the fact that the GGSN
`does not have the SGSN address.
`It has previously been proposed to provide a separate
`interface between the Gateway GPRS Support Node
`(GGSN) and the HLR, which contains the subscription data
`for the mobile station, in order to provide the address of the
`latest Serving GPRS Support Node (SGSN) to the GGSN.
`However, Such would require that an entirely new interface
`with new protocols be established and implemented.
`What is needed, therefore, and an object of the present
`invention, is a technique for informing the Gateway GPRS
`Support Node of the address of the latest Serving GPRS
`Support Node under more generalized circumstances.
`BRIEF SUMMARY OF THE INVENTION
`The address of a latest Serving GPRS Support Node
`25
`(SGSN) is provided to a Gateway GPRS Support Node
`(GGSN) by a special Update SGSN. Address Request mes
`sage which is sent from the SGSN to the GGSN. For a
`Subscriber whose Subscription permits, the address of the
`latest SGSN node is sent in the Update SGSN Address
`Request message for a qualified packet data protocol (PDP)
`context. A qualified PDP context (1) has a static PDP
`address, and (2) is not activated.
`The Update SGSN Address Request message can be sent
`from the SGSN to the GGSN in either a GPRS Attach
`scenario or an Inter-SGSN Routing Area Update Scenario.
`In response to the Update SGSN Address Request message,
`the GGSN sends an Update SGSN Address Response mes
`Sage which adviseS whether the updating of the address for
`the SGSN at the GGSN has been Successful.
`The invention also involves introducing a new field,
`entitled “SGSN. Address Updating Allowed”. The SGSN
`Address Updating Allowed” field appears both (1) in the
`subscription for the mobile station in the mobile stations
`home location register (HLR); and (2) in the PDP context
`information maintained by the SGSN. In this field an opera
`tor can specify that the PDP contexts for the subscriber,
`which PDP contexts have an inactive PDP state and a static
`PDP address, can provide their SGSN address to their GGSN
`following either a successful GPRS attach procedure or an
`50
`Inter-SGSN Routing Area Update procedure. The SGSN
`Address Updating Allowed field is set by an operator, e.g.,
`by operator command.
`BRIEF DESCRIPTION OF THE DRAWINGS
`The foregoing and other objects, features, and advantages
`of the invention will be apparent from the following more
`particular description of preferred embodiments as illus
`trated in the accompanying drawings in which reference
`characters refer to the same parts throughout the various
`Views. The drawings are not necessarily to Scale, emphasis
`instead being placed upon illustrating the principles of the
`invention.
`FIG. 1 is a Schematic view of a cellular telecommunica
`tions network according to an embodiment of the invention
`and showing a mobile Station Served by a first base Station
`system and a first SGSN node.
`
`35
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`FIG. 2 is a schematic view of the cellular telecommuni
`cations network of FIG. 1 but having the mobile station
`served by a second base station system and a second SGSN
`node.
`FIG. 3 is a diagrammatic view of general Signal flow for
`a combined IMSI/GPRS Attach procedure according to a
`mode of the invention.
`FIG. 3A is a more detailed diagrammatic view of the
`signal flow for the combined IMSI/GPRS Attach procedure
`of the mode of FIG. 3.
`FIG. 4 is a diagrammatic view of general Signal flow for
`an Inter-SGSN Routing Area Update procedure according to
`a mode of the invention.
`FIG. 4A is a more detailed diagrammatic view of the
`signal flow for the Inter-SGSN Routing Area Update pro
`cedure of the mode of FIG. 4.
`FIG. 5A and FIG. 5B are diagrammatic views of mobility
`management state models of the mobile station and SGSN
`node.
`
`DETAILED DESCRIPTION OF THE DRAWINGS
`In the following description, for purposes of explanation
`and not limitation, Specific details are Set forth Such as
`particular architectures, interfaces, techniques, etc. in order
`to provide a thorough understanding of the present inven
`tion. However, it will be apparent to those skilled in the art
`that the present invention may be practiced in other embodi
`ments that depart from these specific details. In other
`instances, detailed descriptions of well known devices,
`circuits, and methods are omitted So as not to obscure the
`description of the present invention with unnecessary detail.
`FIG. 1 shows an example cellular telecommunications
`network having GPRS capability for which the invention is
`useful. The network of FIG. 1 is shown using GSM-type
`terminology. While a preferred implementation is described
`in a GSM context/application, the present invention may be
`employed in other radio communications networkS.
`FIG. 1 shows that gateway general packet radio Service
`(GPRS) support node (GGSN) 20 is connected to one or
`more data networks, Such as the Internet, as represented by
`cloud 22. GGSN 20 communicates over a Gn interface with
`one or more Serving general packet radio Service Support
`nodes (SGSN), of which two representative SGSNs are
`shown as 24 and 24. The SGSN 24 communicates with
`(1) home location register (HRL) node 26 using a Gr
`interface; (2) mobile switching center (MSC) node 28
`(which includes visiting location register (VLR) 29) using
`a Gs interface; and (3) base station system (BSS) 30, using
`a Gb interface. The base station system (BSS) 30, commu
`nicates with various mobile radio Stations, Such as mobile
`station (MS) 40 shown in FIG. 1, over an air interface Um.
`A MAP-D protocol is employed for communications
`between HLR 26 and MSC/VLR node 28. A MAP-A
`protocol is employed for communications between MSC/
`VLR node 28, and nodes of base station system (BSS) 30.
`A mirror image of the network configuration above
`described is connected through SGSN 24, the reference
`numerals of the nodes and Systems of mirrored configuration
`having the subscript 2 rather than 1. It should be understood
`that there need not necessarily be an identical mirroring, and
`that Such representation is merely for Sake of illustrative
`convenience. Moreover, more SGSNs may be and likely are
`connected to GGSN 20, so that the overall next work may
`be quite complex.
`A dashed-dotted line shown between each of HLR 26
`and HRL 26 and GGSN 20 indicates that a possible
`
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`communications path could be established between each of
`the HLRs and the GGSN 20. However, Such communica
`tions path would require that an entirely new interface be
`established and implemented. AS explained below, the
`present invention eliminates the need for Such involved
`interfaces/protocols between the HLRs and GGSN 20.
`Mobile station (MS) 40 is capable of using one or more
`general packet radio services (GPRSs). The operator of the
`telecommunications network shown in FIG. 1 has a Sub
`scription agreement for mobile station (MS) 40. The Sub
`Scription agreement specifies various terms and conditions
`concerning and governing operation of mobile Station (MS)
`40. Data including Subscription data reflecting e.g., certain
`ones of these Subscription terms and conditions for mobile
`station (MS) 40 is stored in HLR 26.
`In the above regard, in a telecommunications network
`each mobile Station has a location register which is consid
`ered its “home” register. In the illustrated example, HLR 26
`is the “home” register for mobile station (MS) 40. HRL26,
`thus has a record for each of the mobile stations for which
`it is “home”, including a record for mobile station (MS) 40.
`An example format of a prior art GPRS subscription data
`record stored in HLR 26 is shown in Table 1. The first field
`of a record in HLR 26, identifies the particular mobile
`Station to which the record belongs, the first record contain
`ing the International Mobile Subscriber Identity (IMSI) of
`the mobile Station, which is unique for each mobile Station.
`For each packet data protocol type which the mobile Station
`(MS) 40 is eligible to utilize (depending e.g., on its sub
`Scription agreement), the record in HLR 26 also contains a
`“context'.
`Basically Stated, a “context' is data needed for a Sub
`scriber to use a specific packet data protocol (PDP), for
`example X.25. An example context for one packet data
`protocol (“PDP) is shown as the group of last six fields of
`Table 1. If mobile station (MS) 40 is eligible to use two
`packet data protocols, two Such groups of fields would be
`included in the record; if three packet data protocols are
`eligible, three Such groups are included, and So forth.
`In general, “activation” of a PDP context enables the
`SGSN to establish a PDP context for a subscriber (see Table
`3) and enables the subscriber's mobile station to send and
`receive packet data. A “static PDP address is associated
`with the Subscriber's mobile ID and is allocated at the PDP
`context Subscription.
`45
`For reasons explained below, the current invention aug
`ments the record in the HLR 26 with a new field which is
`shown in Table 2. The field newly added by the present
`invention is entitled the “SGSN. Address Updating Allowed'
`field. The SGSN. Address Updating Allowed” field basically
`specifies whether the subscriber is allowed to update its
`SGSN address to its GGSN when (1) the subscriber is not
`GPRS active and (2) after a GPRS Attach procedure or an
`Inter-SGSN Routing Area Update procedure. It should be
`understood that identity of other fields and the ordering of
`fields in the records of HLR26 are not critical to the present
`invention, but that the format of Table 1 is provided merely
`as an example of one specific implementation.
`At the time shown in FIG. 1, GGSN 20 knows how to
`route incoming requests for packet radio connections to
`mobile station (MS) 40. In particular, at the instance shown
`in FIG. 1, if a data packet connection to mobile station (MS)
`40 were requested, GGSN 20 would consult HLR 26.
`GGSN 20 would learn the SGSN. Address for mobile station
`(MS) 40, e.g., SGSN 24 from the second field of the record
`for mobile station (MS) 40 in HLR 26 (assuming the format
`of Table 1).
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`50
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`55
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`60
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`65
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`A complication occurs when mobile station (MS) 40
`moves to another location that is not served by SGSN 24.
`An example of Such a complication is illustrated as mobile
`station (MS) 40 moves along path 50 of FIG. 1 to the
`position shown in FIG. 2. In the location shown in FIG. 2,
`mobile station (MS) 40 is in radio contact with base station
`system (BSS)30 rather than base station system (BSS) 30,
`and thus comes under the jurisdiction of SGSN 24 rather
`than SGSN 24. However, at this point in time GGSN 20 is
`oblivious to the fact that, for data packet Services, mobile
`station (MS) 40 is now served by SGSN 24 rather than
`SGSN 24.
`Under certain circumstances GGSN 20 would eventually
`be apprised that, in the situation of FIG. 2, mobile station
`(MS) 40 is served by SGSN 24 rather than SGSN 24. One
`such circumstance is when mobile station (MS) 40 seeks to
`activate one of its packet data Services by initiating a packet
`data transmission from mobile station (MS) 40, such acti
`vation being referred to as a PDP context activation. Another
`circumstance accompanies inter-SGSN routing updating
`Signaling. Yet until one of these circumstances occurs,
`mobile station (MS) 40 is unable to receive data packets
`because GGSN 20 does not have the current SGSN address.
`The present invention provides GGSN 20 with the current
`SGSN address, and thereby allows mobile station (MS) 40
`to receive data packets even before mobile station (MS) 40
`performs any PDP context activation. In particular, the
`present invention allows mobile station (MS) 40 to “attach”
`to an SGSN. The present invention enhances MS mobility
`management by transferring the address of the SGSN cur
`rently serving mobile station (MS) 40 to the HLR by way of
`the Gn interface between GGSN and SGSN.
`Thus, the present invention provides GGSN 20 with the
`current SGSN address by having the SGSN send GGSN 20
`its address under certain circumstances. The SGSN address
`is provided to GGSN 20 in a new message known as the
`Update SGSN Address Request message. For a subscriber
`whose subscription permits, the address of the latest SGSN
`node is sent in the Update SGSN Address Request message
`for a qualified packet data protocol (PDP) context. A quali
`fied PDP context (1) has a static PDP address; and (2) is not
`activated. As explained separately below, the Update SGSN
`Address Request message can be sent from the SGSN to the
`GGSN in either a GPRS Attach Scenario or an Inter-SGSN
`Routing Area Update Scenario.
`GPRS Attach Scenario
`Prior to discussing Attach procedure details, it is prelimi
`narily mentioned that a GPRS-attached mobile station can
`use its IMSI to attach to the SGSN. This invention particu
`larly concerns mobile stations with GPRS capabilities; a
`mobile station that is not GPRS-attached makes an IMSI
`attach, as described (for example) in the Global Systems for
`Mobile communication (i.e., GSM). An IMSI-attached
`class-A mobile Station engaged in a circuit Switched (CS)
`connection does not indicate that it is IMSI-attached when it
`performs a GPRS attach. In the attach function, the MS
`provides its IMSI and an indication of which type of attach
`that is to be executed. The different types of attach are IMSI
`attach, GPRS attach, and combined IMSI/GPRS attach.
`IMSI (or old TLLI) is used as an identifier during the
`attach procedure until a new TLLI is allocated. After having
`executed the GPRS lo attach, the mobile station is in
`READY state, and MM contexts are established in the
`mobile station and the SGSN. The mobile station may then
`activate PDP contexts as described in Subclause “PDP Con
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`text Activation and Deactivation Functions” of the GSM
`documentation.
`An IMSI-attached class-C mobile station follows the
`normal IMSI detach procedure before it makes a GPRS
`attach. A GPRS-attached class-C mobile station performs a
`GPRS detach before it makes an IMSI Attach.
`The SGSN address for this particular mobile stations
`location is stored in the HLR so that changes in subscriber
`data can be communicated to the SGSN. If new Subscriber
`data is received in the SGSN, and if the mobile station is
`GPRS-attached, the SGSN may, if required, command the
`mobile station to make a new GPRS attach and new PDP
`context activations So that the new Subscriber data is taken
`into use.
`The GPRS Attach Scenario is first described generally
`with respect to FIG.3, and then in more detail with reference
`to FIG. 3A. The GPRS Attach Scenario, which is a combined
`IMSI/GPRS Attach procedure, is described with reference to
`the example and illustrative network topology presented in
`FIG. 2 in which, yet unknown to GGSN 20, mobile station
`(MS) 40 has just come into the jurisdiction of SGSN 24.
`At step 3-1 of FIG. 3, mobile station (MS) 40 sends an
`Attach Request message to SGSN 24. Step 3-2 depicts
`performance of Identification, Authentication, and IMEI
`operations. At step 3-3 SGSN 24 sends a Update Location
`message to HLR 26. Step 3-4 reflects Cancel Location
`procedures and Insert Subscriber Data (ISD) procedures
`initiated by HLR 26. In connection with these ISD
`procedures, the ISD operation is modified for GPRS in order
`to carry GPRS related information such as PDPTypes, PDP
`Addresses, QoS Subscribed, etc. (See Table 4 of section 13.1
`of TS GSM 03.60).
`Step 3-5 of FIG. 3 shows HLR 26, sending an Update
`Location Ack message to SGSN 24. After receipt of the
`Update Location Ack message, SGSN 24 Sends a new
`message of the invention-the Update SGSN. Address
`Request message-to GGSN 20 as shown by step 3-6. The
`Update SGSN Address Request message provides the new
`SGSN address, i.e., the address of SGSN 24 for all PDP
`40
`contexts which have a Static PDP address, which are not
`activated, and for which an operator has indicated that
`address notification is permitted. Thereafter, GGSN 20
`responds by sending an Update SGSN Address Response
`message to SGSN 24 as indicated by step 3-7. The Update
`SGSN Address Response message advises whether the
`updating requested by the Update SGSN Address Request
`message has been Successful.
`After SGSN 24 has informed, or at least attempted to
`inform, GGSN 20 of the address of SGSN 24, Location
`Update procedures are performed as generally indicated by
`step 3-8. Following Location Update, at step 3-8 SGSN 24.
`sends an Attach Accept message to mobile station (MS) 40.
`Thus, two new GPRS Tunneling Protocol (GTP) messages,
`the Update SGSN. Address Request message and the Update
`SGSN Address Response message, are provided by the
`present invention. These two new GTP messages, as well as
`details of one embodiment of implementation of the general
`procedure shown in FIG. 3, are described in more detail in
`connection with FIG. 3A. Steps shown in FIG. 3 have the
`same steps numbers in FIG. 3A, with FIG. 3A also showing
`various Substeps or Suboperations for procedures and opera
`tions only generally shown in FIG. 3.
`At step 3-1 of FIG. 3A, mobile station (MS) 40 makes its
`identity (e.g., its IMSI) known to the SGSN serving base
`station system 30, i.e., SGSN 24, by sending an Attach
`Request message. The Attach Request message of Step 3-1
`
`8
`includes e.g., the following informational parameters rela
`tive to mobile station (MS) 40: IMSI, MS Class, Classmark,
`CKSN, Attach Type, and DRX Parameters. The Attach
`Request message is Sent via base Station System 30 to
`SGSN 24.
`The informational parameters included in the Attach
`Request message of Step 3-1 are now briefly discussed. The
`“MS Class' parameter indicates whether the mobile station
`is a class-A, class-B, or class-C mobile Station. The “Class
`mark' parameter contains the mobile s