The invention relates to a packet-switched part of a core network in 3G (third generation) mobile networks, and particularly to modification of a logical connection set up between a terminal and a network node, e.g. a gateway GPRS support node (GGSN), responsible for the connection in order to transmit data.
The packet-switched part is implemented in 3G mobile networks on the basis of a general packet radio service at least in the beginning. The general packet radio service GPRS was developed to supplement the GSM and to allow the use of packet-switched applications in a mobile network. In GPRS, the logical connection between a mobile station and a gateway GPRS support node is called a PDP context (packet data protocol context). The PDP context is network-level information, which is used to connect a mobile station MS to different PDP addresses, which are either permanent or temporary network-level GPRS subscriber addresses, and to eliminate this connection after use. The PDP context refers to data to be stored in a mobile station MS, a serving GPRS support node SGSN and a GGSN, when a connection has been activated to an external packet data network. If the user desires to modify his PDP context, he sends a PDP context modification request, including new QoS (quality of service) and TFT (traffic flow template) values, to the SGSN. The SGSN thereafter transmits a PDP context updating request to the GGSN. Based on the TFT parameter in the modification request, the GGSN replaces the original TFT value from the PDP context and returns the PDP context updating response to the SGSN. In the next step a radio access bearer RAB procedure implements RAB modification, whereafter the SGSN acknowledges the PDP context modification to the MS.
A problem in the arrangement described above is that with the present standardized methods it is not possible to return the original TFT value to the GGSN, if the radio network controller RNC does not accept the new QoS profile in the RAB modification, but the TFT parameter value of the modification request remains as a TFT value in the GGSN. For instance, the SGSN cannot return the TFT parameter value, because unlike the QoS value, it is transparent to the SGSN.
An objective of the invention is to develop a method and an apparatus implementing the method so as to solve the aforementioned problem. The objective of the invention is obtained by a method, a system and network nodes, which are characterized by what is disclosed in the independent claims. The preferred embodiments of the invention are disclosed in the dependent claims.
The invention is based on detecting and solving the problem such that the preceding TFT parameter value-is stored at least for-the duration of the modification of the logical connection so that it can replace the value updated in the GGSN, if necessary.
In a preferred embodiment of the invention, in the PDP context modification the original TFT parameter is added to an Update PDP context response message transmitted by the GGSN to the SGSN. An advantage of the embodiment is that the SGSN is informed of the preceding TFT value and it can store it temporarily. It can thus return the original TFT value to the GGSN if the RNC does not accept the new QoS profile in the RAB modification.
The invention will be described in more detail in connection with the preferred embodiments and with reference to the accompanying drawings, in which
The preferred embodiments of the invention will be described below implemented in a 3G WCDMA (wideband code division multiple access) mobile communication system, such as the UMTS (universal mobile telecommunications system). However, the invention is not restricted to these embodiments, but it can be applied in any mobile communication system implementing a GPRS-type packet radio that is capable of transmitting packet data. Other examples of such systems are IMT-2000, IS-41, GSM (Global System for Mobile communications) or other similar mobile communication systems, such as the PCS (Personal Communication System) or the DCS 1800 (Digital Cellular System for 1800 MHz). Specifications of mobile systems in general and of the IMT-2000 and the UMTS in particular develop rapidly. Such development can require additional changes to be made to the invention. Therefore, all the words and expressions should be interpreted as broadly as possible and they are only intended to illustrate and not to restrict the invention. What is essential for the invention is the function itself and not the network element or the device in which the function is implemented.
The UTRAN is a theoretical concept for the 3G radio network and it identifies the network part between the Iu and Uu interfaces, comprising radio network controllers RNC and base stations BS (node B).
A radio network controller RNC is a network node, which controls UTRAN radio resources. It corresponds logically to a GSM base station controller BSC. In
The core network CN can be connected to external networks EN, which can be either circuit-switched CS networks, such as a public land mobile network PLMN, a public switched telephone network PSTN, and an integrated services digital network ISDN, or packet-switched PS networks, such as the Internet and X.25. The core network CN comprises a home location register HLR, a mobile switching centre/visitor location register MSCNLR, a gateway MSC GMSC, an SGSN and a GGSN. The core network described herein is based on a 3G UMTS network. Other types of core networks, for example the IS-41, can comprise other network elements.
The packet-switched part of 3G networks will utilize the GPRS system. The GPRS system, which employs 3G radio access (such as the UMTS) or 2G radio access (such as the GSM), comprises GPRS nodes, i.e. a serving GPRS support node (SGSN) and a gateway GPRS support node (GGSN). The main functions of the SGSN include detecting new GPRS mobile stations MS in its service area, handling registration processes of new MSs with the GPRS registers, transmitting/receiving data packets to/from the GPRS mobile station MS, and maintaining a register of locations of MSs within the service area. The operation of an SGSN according to a first embodiment of the invention will be described below in connection with
The main function of the GGSN is interaction with an external data network. The GGSN connects the operator to the systems outside the GPRS network, such as GPRS systems of other operators, to data networks, such as the IP network or the X.25 network, and to the service centres. The GGSN contains the PDP addresses and routing information, or SGSN addresses, of GPRS subscribers. Based on the TFT parameter, the GGSN filters the packets to different PDP contexts. The operation of a GGSN according to the first embodiment of the invention will be described below in connection with
In the area of the same PLMN, the SGSN and the GGSN are interconnected by an internal operator network, which can be implemented, for example, by means of an IP network.
Subscriber data are stored in the GPRS register HLR, which stores the interdependence between the MS identity, such as MS-ISDN or IMSI (international mobile subscriber identity) and the PDP address.
The mobile station MS can be a simplified terminal intended only for speech, or it can be a terminal for multiple services operating as a service platform and supporting the loading and execution of different service-related functions. The mobile station MS comprises actual mobile equipment ME and a removably associated identification card USIM (universal subscriber identity module), which is also called a subscriber identity module. In this connection, a mobile station MS (i.e. user equipment) generally refers to an entity of the actual terminal and the subscriber identity module. The subscriber identity module USIM is a smart card containing the subscriber identity, executing authentication algorithms and storing authentication and encryption keys and subscriber data needed at the mobile station. The mobile equipment ME is a radio terminal used for radio communication between the mobile station MS and the UTRAN via the Uu interface. The mobile equipment can be any equipment or a combination of several different equipment capable of communicating in the mobile communication system.
The RAB (radio access bearer) service is set up between the mobile station MS and the core network and it contains a service provided by the access layer to the non-access layer for forwarding user data. Different RABs are used according to the subscription, service, desired QoS or the like. The core network controls the set-up, modification and disassembly of RAB over the UTRAN. Set-up and modification of the RAB are functions that the core network initiates and the UTRAN implements.
In order to transmit and receive GPRS data, the mobile station MS has to activate at least one PDP address it wants to use. The PDP refers to a protocol transmitting data as packets. This activation makes the mobile station MS known in the corresponding GGSN, and interaction with external data networks can commence. The PDP context defines different data transmission parameters, such as the PDP type (e.g. X.25 or IP), PDP address, quality of service QoS, and network service access point identifier NSAPI.
A mobile station associated with the GPRS system can commence the PDP context activation at any time by transmitting an Activate PDP context request message to the SGSN. After the SGSN has received the message, it transmits a Create PDP context request message to the GGSN, which sets up the PDP context and transmits it to the SGSN. The SGSN transmits the PDP connection to the mobile station MS in an Activate PDP context response message, and a virtual connection or link is set up between the mobile station MS and the GGSN. As a result, the SGSN forwards all the data packets from the mobile station MS to the GGSN, which in turn forwards all the data packets received from an external network and addressed to the mobile station MS to the SGSN. The PDP context is stored in the mobile station MS, the SGSN and the GGSN. When the mobile station MS moves to the area of a new SGSN, the new SGSN requests for the PDP context from the old SGSN, or if the transfer takes place in an active state, where the signalling connection is open between the UTRAN and the SGSN, the old SGSN immediately gives the PDP contexts to the new SGSN at the beginning of the transfer phase. The GPRS contract comprises one or more PDP addresses. The PDP context refers not only to the GPRS system but to any logical connection which is set up between the terminal and the network element responsible for the connection in order to transmit packet-switched data. Each PDP address is described by one or more PDP contexts in the mobile station MS, the SGSN and the GGSN. Each PDP context can be provided with a traffic flow template parameter (TFT parameter). Based on the TFT parameter, packets are filtered to different PDP contexts of the PDP address. The TFT parameter refers to filtering bases, i.e. to any parameter or group of parameters, on the basis of which a PDP context is selected for a data packet to be transmitted. A PDP address should have at most one PDP context with no associated TFT.
After the activation the PDP context modification occurs according to certain principles and in uniform steps. The modification procedures modify parameters defined for the PDP context during activation. The parameters of each PDP context are preferably defined specifically for this context. A modification request can be initiated by a mobile station MS, an SGSN or a GGSN, and the modification can be commenced at any time.
With reference to
In item 2-2, the SGSN can restrict the desired QoS profile depending on the SGSN capacity, transient load and the QoS profile of the subscriber. The SGSN then transmits an Update PDP context request in message 2-3 to the GGSN. This message includes at least fields: QoS negotiated and TFT. “QoS negotiated” is the value of the QoS profile possibly restricted by the SGSN.
In item 24, the GGSN can further restrict the TFT and QoS negotiated values depending on the GGSN capacity, transient load and the subscriber QoS profile. The GGSN stores the QoS negotiated value and the TFT value it has possibly restricted. Based on the TFT value, the GGSN can modify or remove the TFT value from the PDP context, instead of storing the value. The GGSN thereafter returns the Update PDP context response to the SGSN in message 2-5. This message includes at least a QoS negotiated field. According to the present invention, the original TFT parameter of the preceding PDP context is added as a new field to the Update PDP context response message 2-5.
The SGSN separates the original TFT value from message 2-5 and stores it temporarily in item 2-6. The RAB location procedure thereafter implements successful RAB modification by message 2-7. In a Modify PDP context accept message 2-8, the SGSN acknowledges the PDP context modification to the mobile station MS. In item 2-9, the SGSN eliminates the original TFT parameter from its memory.
The signalling in
The signalling messages and items shown in
According to an embodiment of the invention, the SGSN does not eliminate the original TFT parameter from its memory.
According to another embodiment of the invention, the original TFT parameter is stored in the GGSN. In this embodiment, if the-QoS profile is not accepted in the RAB modification, the SGSN sends the GGSN information that the GGSN should use the original TFT parameter.
According to yet another embodiment of the invention, the original TFT parameter is stored in the mobile station. In this embodiment, if the QoS profile is not accepted in the RAB modification, the SGSN requests the mobile station for the original TFT parameter and forwards it to the GGSN.
According to yet another embodiment of the invention, the original TFT parameter is stored in the mobile station. In this embodiment, if the QoS profile is not accepted in the RAB modification, after obtaining a RAB modification reject message, the mobile station automatically transmits the original TFT parameter to the SGSN, which forwards it to the GGSN.
The terms “packet data protocol” (PDP) and “PDP context” used herein should be understood to refer generally to a state in a mobile station and to at least one network element or functionality producing via the mobile network a data packet transfer path or tunnel with a specified set of parameters. The term “node” used herein should be understood to refer generally to a network element or functionality that processes data packets transmitted via the PDP channel.
In addition to prior art devices, the system, system nodes or mobile stations implementing the operation according to the invention comprise means for storing an original TFT parameter as described above. The existing network nodes and mobile stations comprise processors and memory, which can be used in the functions according to the invention. All the changes needed to implement the invention can be carried out by means of software routines that can be added or updated and/or routines contained in application specific integrated circuits (ASIC) and/or programmable circuits, such as an electrically programmable logic device EPLD or a field programmable gate array FPGA.
It is evident to those skilled in the art that as the technology develops, the basic idea of the invention can be implemented in various manners. The invention and the embodiments thereof are thus not restricted to the examples described above, but they may vary within the scope of the appended claims.
Number | Date | Country | Kind |
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20012561 | Dec 2001 | FI | national |
Filing Document | Filing Date | Country | Kind |
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PCT/FI02/01025 | 12/13/2002 | WO |