Abstract:
The present invention relates to a telecommunication method for first and second wireless networks being coupled, the method comprising the steps of: registration of a mobile terminal with the first wireless network by means of a application layer identifier, registration of the mobile terminal with the second wireless network by means of a network layer identifier storing of the application layer identifier in conjunction with the network layer identifier for routing of a telecommunication link from a data source to the mobile terminal.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     The invention is based on a priority application EP 03 292 228.8 which is hereby incorporated by reference.  
         [0002]     The present invention relates to the field of telecommunication, and more particularly without limitation, to dual mode telecommunication methods and systems.  
         [0003]     Wireless local area network (WLAN) is a promising technology that can be used as a complement technology to UMTS/GPRS at hot-spots to provide high bandwidth and low costs. However the efficient integration of WLAN and UMTS/GPRS is still an open question. Various approaches for WLAN/GPRS integration have been considered in “Mobility management for an integrated network platform”, By Kuladinithi, K.; Konsgen, A.; Aust, S.; Fikouras, N.; Gorg, C., Mobile and Wireless Communications Network, 2002. 4th International Workshop, Pages: 621-625; and “Experimentation of TCP schemes over GPRS &amp; WLAN” By Leang Tzeh Yeu; Liew, J.; Seah, W. K. G., Mobile and Wireless Communications Network, 2002. 4th International Workshop, Pages: 234-238.  
         [0004]     One open issue is the provisioning of packet switch based services over heterogeneous networks constituted of both WLAN and UMTS/GPRS.  
       SUMMARY OF THE INVENTION  
       [0005]     The present invention provides for a telecommunication method for first and second wireless networks which are coupled. Initial network registration of a mobile terminal with the first wireless network (i.e. the way a mobile terminal is initially recognized by the network) is performed based on an application layer identifier, such as a permanent identifier, in particular the MSISDN of the mobile terminal.  
         [0006]     For exmple, the MSISDN of a particular user can have an assigned service description which specifies GPRS and WLAN services for this user. The MSISDN is allocated to the user as part of a subscription process.  
         [0007]     Network registration—in other words “hooking” a mobile terminal to a network to be able to establish a communication link—of the mobile terminal with the second wireless terminal is performed by means of a network layer identifier which is assigned to the mobile terminal by the second network. For example the network layer identifier is a temporary identifier, such as a temporary IP address, in particular a WLAN IP address. Note that “application and network level” terms refer to OSI layered model.  
         [0008]     Typically application layer identifier for registration with the first wireless network is stored on non-volatile storage within the mobile terminal, e.g. on the subscriber identity module (SIM) card. After the mobile terminal has obtained it&#39;s network level identifier from the second wireless network it sends it&#39;s network level identifier to the first wireless network for storage in a mapping table in conjunction with the application level identifier. This mapping table is used for routing of a telecommunication link from a data source to a mobile terminal.  
         [0009]     When the mobile terminal moves outside the hot-spot coverage provided by the second wireless network it sends a corresponding message to the first wireless network such that the temporary identifier which is stored in the mapping table is invalidated. This way it is ensured that no attempt is made to route a telecommunication link to the mobile terminal through the second wireless network, which would fail in this instance. As the mobile terminal itself informs the first wireless network that it has left the hot-spot hand-off latency is drastically reduced.  
         [0010]     In accordance with a further preferred embodiment of the invention the packet data gateway (PDG) is used for mapping of the application layer identifier to the network layer identifier. The packet data gateway is specified in 3GPP TS 23.234 “3GPP system to wireless local area network (WLAN) interworking”. In this instance the MSISDN of the mobile terminal is sent to the packet data gateway as part of the registration procedure. As the packet data gateway performs the assignment of a WLAN IP address to the mobile terminal it has knowledge of this address and thus performs the mapping of the MSISDN to the WLAN IP address.  
         [0011]     In accordance with a further preferred embodiment of the invention an authorization authentication accounting (AAA) server is used to perform the mapping.  
         [0012]     In accordance with a further preferred embodiment of the invention the instance which performs the binding of the two networks selects one of the networks to establish a communication link when both networks are available to provide such a communication link to the mobile terminal. This selection can be based on any criterion, such as load balancing or security level.  
         [0013]     In accordance with a further preferred embodiment of the invention the unit performing the MSISDN/GPRS IP address mapping is reused to perform the MSISDN/WLAN IP address mapping in accordance with the present invention. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0014]     In the following preferred embodiments of the invention are described by way of example by making reference to the drawings in which:  
         [0015]      FIG. 1  is a block diagram of a telecommunication system having coupled wireless networks,  
         [0016]      FIG. 2  is illustrative of a flow chart of a registration method,  
         [0017]      FIG. 3  is illustrative of a flow chart of a routing method.  
     
    
     DETAILED DESCRIPTION  
       [0018]      FIG. 1  shows telecommunication system  100  which has medium bandwidth wireless network  102  and high bandwidth wireless network  104 . Medium bandwidth network  102  and high bandwidth  104  are coupled by means of network coupling component  106 . Preferably network coupling component  106  implements a loose network coupling architecture.  
         [0019]     Medium bandwidth network  102  provides global coverage whereas high bandwidth network  104  provides coverage for hot-spot  108 . Hot-spot  108  is located within the coverage of medium bandwidth network  102 .  
         [0020]     Network coupling component  106  is connected to storage  110 . Storage  110  stores a mapping table for mapping of permanent identifiers to temporary identifiers for the purposes of routing. This will be explained in more detail in the following.  
         [0021]     Wireless dual mode terminal  112  is within the coverage of medium bandwidth network  102  and within hot-spot  108 . Dual mode terminal  112  has non-volatile memory  114  for storage of a permanent identifier. For example non-volatile memory  114  is a SIM card which is inserted in a card reader of dual mode terminal  112 . In this instance the MSISDN, i.e. the telephone number of dual mode terminal  112  can serve as the permanent identifier. Alternatively the IMSI can be used.  
         [0022]     Dual mode terminal  112  has component  116  for operation in medium bandwidth mode. Component  116  is coupled to non-volatile memory  114  for reading of the permanent identifier from non-volatile memory  114 .  
         [0023]     Dual mode terminal  112  has memory  118  which can be a volatile or non-volatile memory for storage of a temporary identifier. Further dual mode terminal  112  has component  120  for operation in high bandwidth mode. Component  120  is coupled to memory  118  for writing and reading of the temporary identifier.  
         [0024]     In operation dual mode terminal  112  registers with medium bandwidth network  102  on the basis of it&#39;s permanent identifier stored in non-volatile memory  114 . The corresponding registration procedure is performed by component  116 .  
         [0025]     Further dual mode terminal  112  registers with high bandwidth network  104  when it is within hot-spot  108 . During the registration procedure high bandwidth network  104  assigns a temporary identifier to dual mode terminal  112  which is stored by component  120  in memory  118 . When the registration procedure of dual mode terminal  112  with high bandwidth network  104  is complete and the temporary identifier has been stored in memory  118  this is signalled from component  120  to component  116 .  
         [0026]     In response component  116  reads the temporary identifier from memory  118  and sends it to medium bandwidth network  102 . Medium bandwidth network  102  sends the permanent identifier and the temporary identifier of dual mode terminal  112  to network coupling component  106  which stores the permanent identifier and the temporary identifier in the mapping table of storage  110 .  
         [0027]     When data source  122  wants to send data to dual mode terminal  112 , such as multi media data, data source  122  provides the permanent identifier of dual mode terminal  112  to medium bandwidth network  102 . Medium bandwidth network  102  forwards the permanent identifier to network coupling component  106  in order to check whether a valid temporary identifier is available in storage  102  for the permanent identifier provided by the data source  122 .  
         [0028]     In other words the mapping table of storage  110  is checked for the presence of the permanent identifier and a corresponding temporary identifier. If no temporary identifier is stored in storage  110  for the permanent identifier this is signalled from network coupling component  106  to medium bandwidth network  102  and a medium bandwidth communication link is established between data source  122  and dual mode terminal  112  via medium bandwidth network  102 .  
         [0029]     If network coupling component  106  retrieves a temporary identifier for the permanent identifier provided from data source  122  from the mapping table stored in storage  110 , the temporary identifier is provided from network coupling component  106  to high bandwidth network  104  and a high bandwidth communication link is formed between high bandwidth network  104  and dual mode terminal  112  for transmission of data from data source  122  over network coupling component  106  and high bandwidth network  104  to dual mode terminal  112 . In one application a so called MMS-message is transmitted this way from data source  122  to dual mode terminal  112 .  
         [0030]     When dual mode terminal  112  is moved outside hot-spot  108  this is recognised by component  120  as coverage from high bandwidth network  104  is lost. This is signalled from component  120  to component  116  which in response sends a message to medium bandwidth network  102  which indicates that dual mode terminal  112  is outside the coverage of high bandwidth network  104 . This is possible due to the fact that medium bandwidth network  102  provides global coverage outside hot-spot  108 .  
         [0031]     In response to the message received from dual mode terminal  112  medium bandwidth network  102  sends a command to network coupling component  106  for the invalidation of the temporary identifier which is stored in storage  110 .  
         [0032]     It is important to note that dual mode terminal  112  and not high bandwidth network  104  initiates the invalidation of the temporary identifier stored in storage  110 . This way it is ensured that the temporary identifier within storage  110  is invalidated with minimal latency. Hence when data source  122  wants to send data to dual mode terminal  112  no unnecessary attempt is made to form a communication link via high bandwidth network  104  as the move of dual mode terminal  112  outside hot-spot  108  is immediately reflected in storage  110 .  
         [0033]      FIG. 2  shows a corresponding flow chart. In step  200  the wireless dual mode terminal registers with the medium bandwidth network. This is done by means of the permanent identifier of the dual mode terminal. In step  202  the dual mode terminal registers with the high bandwidth network when it is within the hot-spot coverage. As part of the registration procedure dual mode terminal receives a temporary identifier from the high bandwidth network in step  204 .  
         [0034]     In step  206  the dual mode terminal sends the temporary identifier to the medium bandwidth network. The temporary identifier is stored in the mapping table for the purposes of routing of communication links to the dual mode terminal. The routing will be explained in more detail with respect to  FIG. 3 .  
         [0035]     When the dual mode terminal moves outside the coverage of the high bandwidth network in step  210  a message is sent from the dual mode terminal to the medium bandwidth network in order to indicate that the dual mode terminal is outside the coverage of the high bandwidth network (step  212 ). In response the temporary identifier stored in the mapping table is invalidated.  
         [0036]      FIG. 3  shows a corresponding routing method. In step  300  a request is received by the medium bandwidth network to establish a communication link to a mobile terminal. The mobile terminal is identified in the request by it&#39;s permanent identifier. In step  302  it is checked whether a valid temporary address is stored for the permanent identifier in the mapping table. If this is the case a communication link is formed via the high bandwidth network to the mobile terminal in order to send the data (step  304 ). If the contrary is the case a communication link is formed via the medium bandwidth network (step  306 ).  
         [0037]     It is to be noted that the present invention is particularly suitable for integrationof GPRS medium bandwidth networks and WLAN high bandwidth networks. In this instance the MSISDN is used as the application layer identifier and the WLAN IP Address is used as the network layer identifier. However the present invention is not limited to any particular network standard but is broadly applicable to telecommunication systems having at least two wireless networks one of which providing global coverage.  
         [0038]     In the case of GPRS/WLAN integration the temporary identifier can be transmitted from the mobile terminal to the GPRS medium bandwidth network by means of the IP protocol. Likewise the mobile terminal can inform the GPRS medium bandwidth network concerning its move outside the hot-spot coverage by means of an IP protocol message.  
         [0039]     Alternatively the mobile terminal sends a packet data protocol (PDP) context activation request as a signalling message to the GPRS medium bandwidth network. The PDP context activation request contains the temporary IP address which has been assigned to the mobile terminal by the WLAN high bandwidth network. The PDP context activation address contains an access point name (APN) which is assigned to the mapping table.  
         [0040]     When the SGSN receives the PDP context activation request it identifies the IP address of the mapping table by means of a domain name server (DNS) on the basis of the APN of the mapping table. The SGSN then forwards the temporary IP address of the mobile terminal as well as its MSISDN to the mapping table over IP protocol. Likewise the temporary IP address is invalidated in the mapping table by sending of a PDP context deactivation request from the mobile terminal to the GPRS medium bandwidth network.  
         [heading-0041]     List of Reference Numerals  
         [none]    
       
           100  telecommunication system  
           102  medium bandwidth network  
           104  high bandwidth network  
           106  network coupling component  
           108  hot-spot  
           110  Storage  
           112  dual mode terminal  
           114  non-volatile memory  
           116  Component  
           118  Memory  
           120  component  
           122  data source