Telecommunication system and method for controlling switching of a user terminal between two networks

p0001The invention relates to a telecommunication system comprising a first network and a second network, and a method for controlling a change of a subscriber terminal between the first network and the second network.

p0002In today's world, the spread of cellular mobile networks, particularly the 3rd generation, ie, the so-called Universal Mobile Telecommunications System in particular, continues to grow. At the same time, further radio networks are being developed which aim to provide broad bandwidths to subscribers in order to transmit large amounts of data in a short time. Such a wireless network has been planned for some time by a large number of people who have joined forces to create a standard for a WiMAX wireless network in a so-called WiMAX, Worldwide Interoperability for Microwave Access, Forum (www.wimaxforum.org). It is intended that subscriber terminals, such as mobile radiotelephones or notebooks, should have access both to conventional mobile radio networks, such as the UMTS network, as well as to the WiMAX radio network. Participants can select the most suitable network according to specific criteria, such as availability, price, quality, etc., and switch between two different networks, if necessary.

p0003When switching between two networks, data loss and / or connection interruptions can occur, which should be avoided. For this purpose, such a changeover between two different networks is supported by a mobility protocol. The task of the mobility protocol is to maintain the existing communication connections of a subscriber when the network is switched, thereby avoiding or minimizing interruptions.

p0004Such a mobility protocol has been defined, for example, by the WiMAX Forum primarily on the basis of the so-called Mobile IP protocol, in particular the Mobile IP protocol version 4, MIPv4, the Internet Engineering Task Force, IETF. The WiMAX Forum has defined two different variants of the use of Mobile IP. On the one hand, a so-called client mobile IP, CMIP, client is defined which is installed directly in the subscriber terminal and handles the signaling for switching between the two networks via the subscriber terminal. On the other hand, a so-called proxy mobile IP, PMIP, client is defined, which is installed in the network and represents a representative for the subscriber terminal in the network with regard to the switching between the networks. The PMIP processes the signaling for the exchange between the networks for the subscriber terminal. In this case, the subscriber terminal largely does not realize the application of the mobility protocol in the network.

p0005Within this framework describes the document <patcit id="pcit0001" dnum="WO2004006447A"><text>WO 2004/006447</text></patcit> A telecommunication system with a cellular mobile radio network and a wireless LAN, W-LAN. A mobile subscriber terminal should be able to switch between both networks without interference. The telecommunication system includes an AAA client that serves both the cellular mobile network and the wireless LAN. The authentication can be performed using the DIAMETER protocol via an AAA client (AAAh, AAAf).

p0006The present invention is based on the object of ensuring a largely problem-free exchange between a cellular mobile radio network and a so-called WiMAX radio network.

p0007According to the invention, this object is achieved by a telecommunication system having the features of claim 1 and a method for controlling a change of a subscriber terminal between a cellular mobile radio network and a WiMAX radio network with the features of claim 10.

p0008On the device side, the telecommunication system according to the invention contains a first network, which is a cellular mobile radio network, a second network which is a so-called WiMAX, Worldwide Interoperability for Microwave Access, Fun Network, and a so-called AAA,

p0009Authorization and Accounting, server for storing subscriber data of a subscriber terminal. The subscriber terminal is designed both for using the first network and the second network. The AAA server is arranged in the telecommunication system such that both subscriber data of the subscriber terminal stored in the AAA server can be accessed both on the basis of the first network as well as on the second network.

p0010On the process side, a change of a subscriber terminal is controlled between a first network, which is a cellular mobile network, and a second network, which is a so-called WiMAX, Worldwide Interoperability for Microwave Access, Fun Network. In this case, subscriber data of the subscriber terminal, which is accessible both to the first network and to the second network, are stored in a so-called AAA, authentication, authorization and accounting server. On subscriber data of the subscriber terminal stored in the AAA server is accessed both on the basis of the first network and on the second network.

p0011Owing to the present invention, a seamless transition between the cellular mobile radio network and the WiMAX radio network can be advantageously made possible so that an interruption of an already existing connection can be completely or almost prevented. This ensures a particularly high level of efficiency and a high quality when changing the network. Furthermore, an AAA infrastructure common to both networks can be easily used to perform the switch. The AAA server already defined in connection with WiMAX can advantageously be configured according to the invention in such a way that it allows access from both networks.

p0012According to a preferred development of the invention, the telecommunication system is configured such that, when a connection between the subscriber terminal and the first network or the second network is established, it checks whether the subscriber terminal is already connected to the respective other network. If this is the case, the subscriber data of the subscriber terminal are retrieved from the AAA server. In a technically simple manner, already existing subscriber data already available in the AAA server can be used from the connection over the other network in order to establish a connection via one of the two networks. This simplifies signaling when switching between the two networks. In addition, it is ensured that the subscriber data necessary for establishing the new connection are, at least in part, the same as those already used for establishing the already existing connection. This contributes to a problem-free change of the network.

p0013The telecommunication system is particularly preferred in such a way that it stores subscriber data generated during the establishment of the connection in the AAA server if the subscriber terminal is not already connected to the respective other network. In this case, the subscriber data stored in the AAA server during the new set-up of the connection can be used for a subsequent change to the other of the networks. To this end, the subscriber data already stored in the AAA server can be accessed and an interruption-free changeover can be carried out.

p0014In a further, particularly preferred embodiment of the invention, a mobility protocol is implemented for the change of the subscriber terminal between the first network and the second network. This mobility protocol supports a secure change and ensures that the components of the telecommunication system involved in the signaling of the changeover can perform the change. The mobility protocol is, in particular, the so-called Mobile IP mobility protocol. The subscriber terminal can thereby retain its IP address when changing to a different network.

p0015A mobile client for the subscriber terminal which is configured for signaling by means of the subscriber terminal during the exchange of the subscriber terminal between the networks is particularly advantageous in the mobility protocol. As a result, a correspondingly equipped subscriber terminal can perform the signaling independently. This simplifies the signaling and keeps their effort low. The mobile client is in particular a so-called Client Mobile IP, CMIP, client of the Mobile IP mobility protocol.

p0016According to a preferred development of the invention, a proxy-mobile client is defined in the mobility protocol, which is designed as a representative for the subscriber terminal for carrying out signaling during the exchange of the subscriber terminal between the networks. Thus, a network switch can also be easily exchanged for a subscriber terminal which is not equipped with a suitable mobile client. The proxy mobile client is, in particular, a so-called proxy mobile IP, PMIP, client of the Mobile IP mobility protocol.

p0017Advantageously, such a proxy mobile client is implemented in the first network. As a result, the cellular mobile radio network is adapted to the signaling by means of a representative for the subscriber terminal on the basis of the mobility protocol. In a particularly simple manner, the cellular mobile radio network can thus carry out the switch and advantageously access the AAA server, which in turn also transmits data to the cellular mobile radio network.

p0018According to a further preferred embodiment of the invention, a so-called home agent, HA, for a home network assigned to the subscriber terminal, and a so-called foreign agent, FA, for a foreign network which can be used by the subscriber terminal, which is not its home network, are defined in the mobility protocol. The external agent, FA, is designed in such a way that it receives signaling and useful data coming from the home network of the subscriber terminal and directed to the subscriber terminal. The home agent, HA, can, in particular, be a special computer or router which is connected to the home network of the subscriber terminal. The home agent transmits incoming data packets to the subscriber terminal, in particular in the home network for the subscriber terminal, if this is not in the home network. The home agent also manages the location information of the subscriber terminal. The outside agent, FA, may also be a special computer or router connected to the external network other than the home network of the subscriber terminal. The foreign agent provides routing services to the third-party network for the subscriber terminal located in the area of ​​the third-party network. In particular, the foreign agent redirects data packets transmitted from the home agent of the subscriber terminal to the subscriber terminal. The terms home network and third-party network are used here in terms of the terminology relevant to the mobility protocol.

p0019It is particularly preferred that a third-party agent, FA, is provided in the first network, which is designed in such a way that it relays mobility protocol-specific signaling data between the proxy-mobile client and the home agent while relaying actual user data between the subscriber terminal and the home agent. In this technically simple manner, an effective forwarding of data from and to the subscriber terminal is possible.

p0020According to a further preferred embodiment of the invention, the subscriber data which can be stored in the AAA server contains at least one, in particular all, of the following data: data which are used for a so-called mobile security association MSA for protecting a transmission of mobility protocol-specific signaling data between The subscriber terminal and the home agent, such as, for example, a common secret key for generating a so-called message authentication code, MAC, an indication of an algorithm for generating the message authentication code, MAC, a reproduction protection, etc., an address The home agent of the subscriber terminal and - a home address of the subscriber terminal in his home network. One or more, in particular all, of this information can effectively ensure a smooth transition between the two networks.

p0021Particularly preferably, the telecommunication system is designed in such a way that, during a change of the subscriber terminal between the first network and the second network, it maintains a connection of the subscriber terminal to one of the two networks, in particular for a predefinable duration, before the change occurs Subscriber terminal to the other of the two networks. As a result, it can advantageously be ensured that the newly established connection has proved successful and functions before the "old" connection which already existed prior to the construction of the new connection is resolved. If necessary, it is also simply possible to go back to the "old" connection again and thereby have a relapse position.

p0022According to a preferred development of the invention, the first network is a network according to the so-called Universal Mobile Telecommunications System, UMTS, Standard. The combination of UMTS network and WiMAX network gives the participant a particularly great freedom of movement and comfort.

p0023Further advantageous embodiments and further developments of the invention can be gathered from the description with reference to the drawing.

p0024The invention is explained in more detail below with reference to the exemplary embodiments shown in the schematic figures of the drawing. It shows:<ul><li><figref idrefs="f0001">FIG</figref> A first exemplary embodiment of a telecommunication system according to the invention having a UMTS network and a WiMAX network, each having a proxy mobile IP client of a mobility protocol;</li><li><figref idrefs="f0002">FIG</figref> 2 shows a first sequence diagram in which the temporal signaling sequence is executed during a setup of a connection of a subscriber terminal into the UMTS network of the telecommunication system according to FIG <figref idrefs="f0001">FIG</figref> Is shown;</li><li><figref idrefs="f0003">FIG</figref> 2 shows a second sequence diagram in which the temporal signaling sequence in the case of a setup of a connection of the subscriber terminal into the WiMAX network of the telecommunication system according to FIG <figref idrefs="f0001">FIG</figref> Is shown;</li><li><figref idrefs="f0004">FIG</figref> A second exemplary embodiment of the telecommunications system according to the invention with the UMTS and the WiMAX network, the subscriber terminal having a client mobile IP client of the mobility protocol, and FIG</li><li><figref idrefs="f0005">FIG</figref> A third sequence diagram, the temporal signaling sequence in the case of a setup of a connection of the subscriber terminal into the UMTS network of the telecommunications system <figref idrefs="f0004">FIG</figref> Is shown.</li></ul>

p0025In the figures of the drawing, identical or functionally identical elements and signals are provided with the same reference symbols, unless otherwise stated.

p0026The <figref idrefs="f0001">FIG</figref> FIG. 1 shows a first exemplary embodiment of a telecommunications system 1 according to the invention with a first network, which is here a UMTS network 2, and a second network, which is a WiMAX network 3. The UMTS network 2 has a so-called UMTS Terrestrial Radio Access Network, UTRAN, 4, which is used as an access network of the UMTS network 2. In addition, The UMTS network 2 also contains a so-called serving GPRS support node, SGSN, 5, which is a higher control unit of the UMTS network 2 and is connected to a special network node, the so-called gateway GPRS support node, GGSN, The WiMAX network 3 corresponds largely to the structure specified by the WiMAX Forum. The WiMAX network 3 contains a so-called Access Service Network, ASN, 7 and, in addition, a so-called Connectivity Service Network, CSN. In the present exemplary embodiment, the CSN of the WiMAX network 3 is combined with the so-called public land mobile network, PLMN, of the UMTS network 2 to form a common network PLMN / CSN 8 for simplification of the display. However, the PLMN and the CSN may also be separate networks. In particular, it is possible that both the UMTS network 2 and the WiMAX network 3 have the same operator.

p0027The telecommunication system 1 further comprises a mobile station 9, which is a subscriber terminal and is a mobile telephone. The mobile station 9 has both access to the UMTS network 2 as well as the WiMAX network 3 and can switch between the two networks. To illustrate this, the mobile station 9 is shown in FIG<figref idrefs="f0001">FIG</figref> Twice. On the one hand, it is connected to the UTRAN 4 of the UMTS network 2 and, on the other hand, to a base station BS 10 of the WiMAX network 3 arranged in the ASN 7. For switching between the two networks, a mobility protocol is implemented in the telecommunications system 1, which supports the change from one of the networks to the other. The mobility protocol is the so-called mobile IP, MIP, protocol. The MIP defines a home agent, HA, to which the mobile station 9 is assigned. In the present exemplary embodiment, a home agent HA 11 is arranged in the common network 8. The MIP also defines a foreign agent, FA. In the present case, a first external agent FA 12 is arranged in the GGSN 6 of the UMTS network 2. A second external agent FA 13 is present in a gateway ASN-GW 14 of the ASN 7 of the WiMAX network 3. The Heimagent HA 11 is connected both to the foreign agent FA 12 and to the foreign agent FA 13. The foreign agent FA 12 is also connected to the SGSN 5 and the foreign agent FA 13 to the base station 10.

p0028In the use of the mobility protocol defined by the WiMAX Forum, a proxy mobile client is also defined, which is designed for signaling when the mobile station 9 is switched between the two networks 2 and 3. The proxy mobile client is here a Proxy Mobile IP, PMIP, client of the mobility protocol. The PMIP serves as a representative for the mobile station 9, so that the mobility protocol does not have to be installed here. A first PMIP client 15 is present in the UMTS network 2. In the present exemplary embodiment, the PMIP client 15 is arranged in the GGSN 6. However, this is not necessarily so. The PMIP client 15 can also be arranged separately from the GGSN 6 in the UMTS network 2. In the<figref idrefs="f0001">FIG</figref> The PMIP client 15 is connected to the foreign agent FA 12. A second PMIP client 16 is present for the WiMAX network 3 in the ASN 7. The PMIP client 16 is located in the<figref idrefs="f0001">FIG</figref> With the foreign agent FA 13. The Heimagent HA 11 also serves as a transition to further areas of the telecommunication system 1<figref idrefs="f0001">FIG</figref> A so-called correspondent node, CN, 17, which, for example, can be a web server on the Internet.

p0029A so-called authentication, authorization and accounting, AAA, server 18 is arranged in the common network PLMN / CSN 8. This AAA server 18 supports, above all, the WiMAX network 3 the authentication, authorization and authorization as well as the billing of a transmission of communication data or messages. For communication with the AAA server 18, an AAA client 19 is present in the UMTS network 2 in the GGSN 6, and in the ASN-GW in the WiMAX network 3. *** " 14 an AAA proxy 20 is present. The AAA server 18 is connected here both to the UMTS network 2, namely to the AAA client 19, as well as to the WiMAX network 3, namely the AAA proxy 20. According to the invention, both the UMTS network 2 and the WiMAX network 3 can access the AAA server 18. Accordingly, data can be transmitted from the AAA server 18 to the two networks 2 and 3.

p0030In the AAA server 18, it is possible to store and manage, in particular, those data which are assigned to the mobile station 9 and are necessary for a change of the mobile station 2 from the UMTS network 2 to the WiMAX network 3, or vice versa, to perform the necessary MIP operations And signaling. The information required to set up a "new" connection is largely the same as the "old" connection to the network to which a connection already exists. Viewed from the viewpoint of the Heimagenten HA 11, behind the change to another network, a simple change of a so-called care-of address, CoA. This CoA corresponds to the address of the mobile station 9 in one of the foreign networks, ie, the address at which the mobile station 9 is accessible when it is in the foreign network. Such a change of the CoA can be carried out during the signaling by means of a so-called registration request. The data stored in the AAA server 18 for the mobile station 9, which can be accessed in the event of a change of the network 2 or 3, are in particular: - data, MSA data for a so-called mobile security association, A protection of a transmission of mobility protocol-specific signaling data between the mobile station 9 and the home agent 11, such as a common secret key for generating a so-called message authentication code, MAC, an indication of an algorithm for generating the MAC, a reproduction protection, Etc., an address HA @ of the home agent 11 of the mobile station 9, and a home address HoA of the mobile station 9 in its home network 8 (in the WiMAX standard, this home address is called Point of Attachment, PoA). This information is generated in the first dialup of the mobile station 9 in one of the two networks 2 or 3 and is stored in a specific area of ​​the AAA server 18. If the network 2 or 3 is switched, the information can then be interrogated and retrieved. The information is then transmitted to the PMIP client of the "new" network 2 or 3, so that the latter can perform the necessary MIP operations and signaling for performing the change. In the case of the change, the MSA data, the HA @ and the HoA remain the same, and only the CoA changes.

p0031The <figref idrefs="f0002">FIG</figref> 14 shows a first sequence diagram in which the temporal signaling sequence follows a configuration of a connection of the mobile station 9 to the UMTS network 2 of the telecommunication system 1 <figref idrefs="f0001">FIG</figref> Is shown. Initially, the mobile station 9 authenticates via the SGSN 5 and a so-called home location register, HLR, by means of a so-called authentication and key agreement, AKA, in a conventional GPRS / UMTS PS procedure. The SGSN 5 then receives the subscriber profile of the mobile station 9 from the HLR. This access to the UMTS network 2 via the SGSN 5 is not relevant to the invention and will therefore not be further described and described in the<figref idrefs="f0002">FIG</figref> not shown. The following description of a so-called Packet Data Protocol, PDP, context creation procedure using the<figref idrefs="f0002">FIG</figref> Applies both in the case where the mobile station 9 establishes a "new" connection to the UMTS network 2 without previously already being connected to the WiMAX network 3 and in the event that the mobile station 9 has a "new" connection The UMTS network 2 while it is already connected to the WiMAX network 3.

p0032In the <figref idrefs="f0002">FIG</figref> Various components of the telecommunication system 1 involved in the signaling are shown. In a first step 21, the mobile station 9 transmits a so-called PDP context request request via the SGSN 5 to the GGSN 6. In this case, an access point, a so-called access point name APN, is advantageously selected on the GGSN 6, which roam between the WiMAX Network 3 and the UMTS network 2. Such an APN must, for example, provide a PMIP functionality for this purpose, and it must also be possible to reach via it both the home agent HA 11 by way of a MIP signaling for a data transport as well as the AAA server 18 via the AAA infrastructure. Alternatively, it is also possible for the subscriber profile assigned to the mobile station 9 to stipulate that only this particular APN with the PMIP functionality may be selected for the mobile station 9, and thus other APNs are not available for the change.

p0033After the GGSN 6 has received the PDP context enable request, it sends a so-called AAA request to the AAA server 18 in a step 22. This is done via the AAA client 19, which is arranged in the GGSN 6. The AAA request may include a network access identifier, NAI, which may be provided, in particular, by the mobile station 9, together with a password, to provide additional security for access to APN services. The AAA request may further include an International Mobile Subscriber Identity, IMSI, as an identification for the mobile station 9 in the UMTS network 2 and / or a canonical NAI, which is an identification for the subscriber data in the AAA server 18. *** " One such NAI is, in particular, in the specification 3GPP TS 29.061: "3rd Generation Partnership Project, Technical Specification Group Core Network and Terminals, Interworking between the Public Land Mobile Network (PLMN) "; Section 16. The derivation of a canonical NAI from the IMSI is described, in particular, in the specification 3GPP TS 23.003: "3rd Generation Partnership Project, Technical Specification Group Core Network and Terminals, Numbering, Addressing and Identification, Release 6". For further information please refer to these specifications. On the basis of the information transmitted in step 22, the AAA server 18 must be able to access the matching subscriber data stored therein.

p0034In a further step, the AAA server 18 responds to the GGSN 6 by means of a so-called AAA reply and transmits the following parameters or indications: an IP address serving as the home address HoA of the mobile station 9 in the MIP (this address is also referred to as PoA according to Of the WiMAX standard), an address HA @ of the home agent HA 11, and other data required to communicate between the PMIP client 15, which here assumes the role of the mobile station 9, and the home agent HA 11 using an MSA. Optionally, an address of the original ASN-GW 14 can additionally be transmitted. If such an address is transmitted to the ASN-GW 14 and is received by the GGSN 6, the GGSN 6 can optionally establish a so-called R4 tunnel to the ASN-GW 14. The data described here are already stored in the AAA server 18, as long as an "old" connection to the WiMAX network 3 exists, because of this "old" connection. If this "old" connection does not exist, this information is first generated and then stored in the AAA server 18.

p0035In a next step 24, the GGSN 6 triggers the PMIP client 15 by means of a so-called Start_PMIP command. This initiates the MIP registration, and the MIP-specific data received from the AAA server 18 is passed on from the GGSN 6 to the PMIP client 15. The PMIP client 15 can then confirm receipt of this information in a step 25 by means of a start_PMIP_ACK message to the GGSN 6.

p0036In a subsequent step 26, the PMIP client 15 transmits a so-called MIP registration request to the home agent 11. The address of the foreign agent 12 is used as CoA address and the HoA of the mobile station 9 supplied by the GGSN 6. Advantageously, it is possible to maintain the "old" MIP relationship between the home agent 11 and the third party 13 of the WiMAX network 3. This can be done, for example, by means of a special flag in the signaling of the PMIP client 15, which is set for this purpose. In this case, the home agent can forward data packets to both foreign agents, the "new" third party agent 12, and the "old" third party agent 13. This ensures a still further improved seamless transition between the two networks 2 and 3 with an uninterrupted connection to the mobile station 9 . This parallel connection to both networks 2 and 3 can be maintained, in particular, for a certain, predefinable time period, which can be selected appropriately, until it is ensured that the "new" connection to the UMTS network 2 performs its function safely and stably. When the mobile station 9 terminates the connection to the WiMAX network 3, the PMIP client 16 of the WiMAX network 3 registers its bindings. This then results in the MIP relay tunnel being dismantled. Alternatively, it may be possible for the PMIP client 16 to degrade the MIP relay tunnel when it receives a message that the mobile station 9 is using the UMTS network 2 without aborting the connection to the WiMAX network 3. *** " In this case, the PMIP client 16 can re-establish the MIP relay tunnel in a simple manner when the PMIP client 16 receives a message that the mobile station 9 wishes to communicate again via the WiMAX network 3. *** " This avoids a waste of resources by sending data over two connections, though it is sufficient to transfer the data only over one.

p0037If the mobile station 9 has not previously been connected to the WiMAX network 3, the home agent 11, in a next step 27, contacts the AAA server 18 to inquire about the MSA data and the address HoA. With this information, the MSA can then be established between the PMIP client 15 and the home agent HA 11. In a subsequent step 28, the data is transferred from the AAA server 18 to the home agent HA 11. In this embodiment variant, the home agent HA 11 requests the data from the AAA server 18. It is also possible for the AAA server 18 to transmit the necessary information to the home agent 11 after the step 22. Steps 27 and 28 are not necessary here as long as the mobile station 9 is already connected to the WiMAX network 3 beforehand. In this case, the information is readily known to the home agent HA 11.

p0038In a step 29, the home agent HA 11 sends a so-called MIP Registration Reply, Reg_Reply, message to the PMIP client 15. This transmission of the message takes place via the foreign agent 12. Subsequently, the PMIP client 15 responds with a Reg_Complete message in a step 30, To report the successful MIP registration to GGSN 6. In a subsequent step 31, the GGSN 6, with an Activate PDP Context Reply message, assigns the obtained address HoA to the mobile station 9 and completes the structure of the PDP context.

p0039The mobile station 9 can now begin sending and receiving data packets via the GGSN 6 of the UMTS network 2. *** " When receiving useful data for the mobile station 9, these are forwarded by the third party 12 to the mobile station 9, while the signaling is processed via the PMIP client 15, as described above. If an R4 tunnel has previously been set up to the "old" ASN-GW 14, this can be removed when the GGSN 6 recognizes the reception of data from the home agent 11 for the mobile station 9.

p0040The <figref idrefs="f0003">FIG</figref> 2 shows a second sequence diagram in which the temporal signaling sequence follows a configuration of a connection of the mobile station 9 into the WiMAX network 3 of the telecommunication system 1 <figref idrefs="f0001">FIG</figref> Is shown. In this flowchart, a change from the UMTS network 2 takes place to the WiMAX network 3. The WiMAX procedures essentially remain unchanged compared to the WiMAX standard. Here, however, MIP subscriber data of the mobile station 9 are stored in the AAA server 18, which were generated in the previous configuration of the "old" connection in the UMTS network 2. These subscriber data can be provided by the AAA server for the signaling when switching to the WiMAX network 3. In the case where the mobile station 9 establishes a connection to the WiMAX network 3 for the first time without a connection to the UMTS network 2, new MIP subscriber data are generated by means of the AAA server 18, as in the conventional WiMAX procedures , And these MIP subscriber data are then stored in the AAA server in order to be called upon a subsequent change of the network.

p0041First, in step 32 an access authentication for the mobile station 9 is handled on the WiMAX network 3 by the AAA server 18. The MSA data and other MIP data are transferred from the AAA server 18 to a so-called authenticator. This authenticator is located in the ASN 7. The authenticator can be used to determine whether the mobile station 9 is allowed to use the WiMAX network 3 or not. In particular, the PMIP client 16 is arranged on the authenticator. In the<figref idrefs="f0003">FIG</figref> The Authenticator and the PMIP client 16 are combined into one common component. In step 32, an AAA key for generating the message authentication code, MAC, the address HA @ and the IP address HoA of the mobile station 9 are thus transmitted to the authenticator in particular. In a subsequent step 33, in particular an ID of the mobile station 9 and the IP address, HoA or PoA, of the mobile station 9 are then forwarded to the ASN-GW 14. The ASN-GW 14 and the foreign agent 13 fulfill different functions, but are simpler in the embodiment<figref idrefs="f0003">FIG</figref> To a common component.

p0042In steps 34, 35 and 36, the mobile station 9 requests its IP address to the ASN-GW 14. In this case, the ASN GW 14 plays the role of a so-called Dynamic Host Configuration Protocol, DHCP, server. The flow corresponds to the conventional WiMAX procedures via a DHCP Discover message from the mobile station 9 to the ASN-GW 14 in step 34, a subsequent DHCP offer message from the ASN-GW 14 to the mobile station 9 in step 35, and a DHCP request message of FIG Of the mobile station 9 to the ASN-GW 14 in the step 36.

p0043In a step 37, the IP address of the mobile station 9, previously transmitted to the authenticator, is transmitted from the ASN-GW 14 to the PMIP client 16 by means of a PoA_Address message. The reception of the IP address HoA or PoA is acknowledged by the PMIP client 16 with a PoA_Address_Ack message in a step 38.

p0044Receiving the PoA_Address message from PMIP client 16 also causes the MIP procedure. This is carried out in subsequent steps 39-44. In step 39, the MIP registration procedure is initiated by means of a MIP Registration Request message. Steps 39-44 correspond largely to steps 26-29, which are described in connection with FIG<figref idrefs="f0002">FIG</figref> Have been described. The "old" MIP relationship is, accordingly, the relationship between the home agent 11 and the third party agent 12 of the UMTS network 2 and the "new" MIP relationship. In this case, the "old" foreign agent is the foreign agent 12 and the "new" foreign agent is the foreign agent The one between the home agent 11 and the third party 13 of the WiMAX network 3. A further repetition of this situation is dispensed with here.

p0045The release of the IP address HoA, PoA of the mobile station 9 to the mobile station 9 was delayed by the preceding steps, in particular for the MIP registration procedure. In steps 45 and 46, the release of the IP address HoA, PoA is now initiated using DHCP gating release and DHCP gating messages. In a step 47, the ASN-GW 14 sends a DHCP Ack message to the mobile station 9 so that it can then start transmitting data packets.

p0046In the course of the procedure for <figref idrefs="f0003">FIG</figref> It is also possible to obtain the address of the foreign agent 12 as "old ASN-GW". This indicates that the mobile station 9 is currently registered in the UMTS network 2. As a result, the "new" ASN-GW 7 can establish a so-called R4 tunnel to the GGSN 6 in order to prevent a loss of data during the changeover of the network. This R4 forwarding tunnel can then be dismantled as soon as it is no longer required.

p0047The <figref idrefs="f0004">FIG</figref> Shows a second exemplary embodiment of the telecommunications system 1 according to the invention with the UMTS network 2 and the WiMAX network 3. In contrast to the first exemplary embodiment according to FIG <figref idrefs="f0001">FIG</figref> The two networks 2 and 3 here contain no PMIP clients, which perform the signaling for the change of the network as a representative for the mobile station 9. In the present exemplary embodiment, the functionality for implementing the mobility protocol Mobile IP, MIP, is directly shifted to the mobile station 9. This has a MIP client. The telecommunication system 1 according to FIG<figref idrefs="f0004">FIG</figref> Has, apart from the two PMIP clients 12 and 13, the same components as the telecommunication system 1 according to FIG <figref idrefs="f0001">FIG</figref>.

p0048In the following, <figref idrefs="f0005">FIG</figref> A procedure in which the mobile station 9 establishes a connection to the UMTS network 2 is described. This can be done both by switching from the WiMAX network 3 to the UMTS network 2, as well as from the situation in which the mobile station 9 has not previously been connected to the WiMAX network 3. In a step 48, the mobile station 9 establishes a so-called PDP context with the UMTS network 2. For this purpose, an Activate FDP Context Request message is transmitted from the mobile station 9 to the GGSN 6. If the mobile station 9 already knows that it may later switch to the WiMAX network 3, it is advantageous to use an APN which supports MIP and the changeover to the WiMAX network 3. In step 49, an Activate PDP context reply message is then transmitted from the GGSN 6 to the mobile station 9. The PDP context is established, whereby the mobile station 9 is not assigned an IP address here. This is done at a later date, during the MIP registration procedure. This is a conventional approach, as described, for example, in the 3GPP TS 29.061 specifications: "3rd Generation Partnership Project," "Technical Specification Group Core Network and Terminals, Interworking between the Public Land Mobile Network (PLMN) ), Release 6 ", and 3GPP TS 29.060:" 3rd Generation Partnership Project "," Technical Specification Group Services and System Aspects "," General Packet Radio Service (GPRS), Service description, Stage 2, Release 6 ". In a next step 50, the foreign agent 12 begins to send agent advertisements to the mobile station 9. Thereby the mobile station 9 receives a CoA and starts the MIP registration procedure.

p0049In subsequent steps 51-56, a MIP registration procedure is performed for the case where the mobile station 9 has not previously been connected to the WiMAX network 3. *** " Then, the mobile station 9 is likely to have no data, in particular MSA data and other MIP data, such as the addresses HA @ and HoA, for performing the MIP registration. The AAA infrastructure provided, in particular the AAA server 18, can therefore be used to generate this information. Upon receipt of the Reg_Reply message in step 56 by the mobile station 9, it has all the necessary information to begin sending and receiving data.

p0050In the case where the mobile station 9 has previously been connected to the WiMAX network 3 and thus a changeover from the WiMAX network 3 to the UMTS network 2, steps 51-56 are not performed. Instead, after step 50, a step 57 is performed in which a Reg_Req message is transmitted from the mobile station 9 to the home agent 11 via the foreign agent 12 to perform the MIP registration procedure. Subsequently, a Reg_Reply message is sent from the home agent 11 via the foreign agent 12 to the mobile station 9, after which the mobile station 9 can then start sending and receiving data. In this case, it is not necessary to involve the AAA infrastructure in the MIP procedure, since the mobile station already contains all the MIP necessary for carrying out the exchange via its connection to the WiMAX network 3.

p0051In the case where the mobile station 9 wishes to establish a connection to the WiMAX network 3, this procedure for establishing this connection is performed essentially as described above with reference to FIG <figref idrefs="f0003">FIG</figref> Described procedure. However, instead of the PMIP client 13, the mobile station 9 appears directly here. First, the mobile station 9 performs WiMAX access authentication. If the mobile station 9 has not previously been connected to the UMTS network 2, the AAA server 18 sends new MIP data, such as MSA data, the addresses HA @ and HoA, to the mobile station 9. If the mobile station 9 has previously been connected to the UMTS network 2 , The AAA server 18 detects this and omits sending the MIP indications to the mobile station 9 since they already exist there. Alternatively, however, the AAA server 18 can still transmit the MIP data for the sake of simplicity. The mobile station 9 can then perform a normal MIP registration procedure.

p0052Although the present invention has been described above with reference to a preferred exemplary embodiment, it is not limited thereto, but can be modified in a variety of ways.