Abstract:
The invention relates to a method for supporting a data exchange between terminal equipment and a mobile communication network via a mobile terminal. The method comprises at the mobile terminal receiving from the terminal equipment a request to establish a connection to the mobile communication network for exchanging data and forwarding this request to the mobile communication network. The method further comprises in case a failure occurs concerning the requested connection and an indication of a cause of the failure is received at the mobile terminal from the mobile communication network, forwarding the indication to the terminal equipment. The invention relates equally to a corresponding mobile terminal, to a corresponding terminal equipment, to a corresponding system and to a corresponding software program product.

Description:
FIELD OF THE INVENTION  
       [0001]     The invention relates to a method for supporting a data exchange between terminal equipment and a mobile communication network via a mobile terminal. The invention relates equally to a corresponding mobile terminal, to a corresponding terminal equipment, to a corresponding system and to a corresponding software program product.  
       BACKGROUND OF THE INVENTION  
       [0002]     It is known in the art to enable terminal equipment, which is not capable of directly accessing a mobile communication network itself, to access such a mobile communication network via a mobile terminal.  
         [0003]     The technical specification 3GPP TS 27.060 V5.4.0 (2003-06): “Technical Specification Group Core Network; Packet Domain; Mobile Station (MS) supporting Packet Switched Services” defines for example requirements for an interworking between terminal equipment and a mobile terminal for the Packet Domain, including the protocols and signaling needed to support Packet Switched services.  
         [0004]     When a mobile terminal tries to establish a connection to a mobile communication network upon a request by terminal equipment, the setup may fail due to various reasons, for example due to insufficient network resources. Equally, an already established connection may be released from the network side prematurely due to various reasons, for example due to an error situation in the mobile communication network. The failure does not necessarily have to be in the mobile communication network itself, but may also be reported to the mobile communication network, for instance by an external network, which the mobile terminal tries to access via the mobile communication network.  
         [0005]     When a mobile communication network rejects a request for an establishment of a connection or releases an established connection, it usually informs the mobile terminal about the respective cause of the failure. The technical specification 3GPP TS 24.008 V6.1.0 (2003-06): “Technical Specification Group Core Network; Mobile radio interface Layer 3 specification; Core network protocols; Stage 3”, for instance, associates to this end GPRS specific cause values for a session management to various failure causes. A cause value which is transmitted by a mobile communication network to a mobile terminal may cause a corresponding textual error message to be displayed on a user interface of the mobile terminal.  
         [0006]     There is no mechanism, however, to inform as well terminal equipment trying to access the mobile communication network via the mobile terminal why a requested connection is not established or why an established connection is released. This is a disadvantage, since users using their terminal equipment do usually not look in parallel at their mobile terminal.  
       SUMMARY OF THE INVENTION  
       [0007]     The invention facilitates the establishment and maintenance of a connection between terminal equipment and a mobile communication network via a mobile terminal.  
         [0008]     A method for supporting a data exchange between terminal equipment and a mobile communication network via a mobile terminal is proposed, which comprises at the mobile terminal receiving from the terminal equipment a request to establish a connection to the mobile communication network for exchanging data and forwarding the request to the mobile communication network. The method further comprises in case a failure occurs concerning the requested connection and an indication of a cause of the failure is received at the mobile terminal from the mobile communication network, forwarding the indication to the terminal equipment.  
         [0009]     Moreover, a mobile terminal is proposed which comprises a transceiver enabling an exchange of signals with a mobile communication network and in addition an interface enabling an exchange of signals with other devices. The proposed mobile terminal further comprises a processing component for receiving from terminal equipment via the interface a request to establish a connection to a mobile communication network for exchanging data, for forwarding the request to a mobile communication network via the transceiver, and in case a failure occurs concerning the connection and an indication of a cause of the failure is received from the mobile communication network, for forwarding the indication to the terminal equipment.  
         [0010]     Moreover, terminal equipment is proposed which comprises an interface enabling an exchange of signals with other devices. The proposed terminal equipment further comprises a processing component for requesting a mobile terminal via the interface to establish a connection to a mobile communication network, for receiving from a mobile terminal an indication of a cause of a failure concerning a requested connection and for processing a received indication of a cause of a failure.  
         [0011]     Moreover, a system is proposed which comprises the proposed mobile terminal, the proposed terminal equipment and a mobile communication network.  
         [0012]     Finally, a software program product is proposed, in which a software code for supporting a data exchange between terminal equipment and a mobile communication network via a mobile terminal is stored. The software code realizes the following steps when running in a processing component of a mobile terminal: Receiving from a mobile communication network an indication of a cause of a failure concerning a connection which has been requested by terminal equipment via the mobile terminal and forwarding the indication to the terminal equipment.  
         [0013]     The invention proceeds from the idea that an indication of the cause of a failure provided by a mobile communication network to a mobile terminal can be forwarded by the mobile terminal to a terminal equipment, if the failure relates to a connection between the mobile terminal and the mobile communication network requested by the terminal equipment.  
         [0014]     It is an advantage of the invention that information on the cause of a failure concerning a connection which has been requested by the terminal equipment is available as well at the terminal equipment. The terminal equipment may make use of the received information for example by displaying it to a user via a user interface of the terminal equipment or by storing it for a later evaluation.  
         [0015]     The failure for which a cause is provided may be a failure resulting in a rejection of the request to establish a connection, i.e. the failure may occur before the connection is actually established. Alternatively, the failure for which a cause is provided may be a failure resulting while a connection is established.  
         [0016]     For the connection between the terminal equipment and the mobile terminal, for instance the Point-to-Point Protocol (PPP) can be used. PPP provides a standard method for transporting multi-protocol datagrams over point-to-point links.  
         [0017]     If the connection between the terminal equipment and the mobile terminal is PPP-based, the indication of a failure cause can be forwarded to the terminal equipment in particular in the data field of an Link Control Protocol (LCP) Terminate Request message described in the IETF RFC 1661 “The Point-to-Point Protocol (PPP)” by W. Simpson, (Editor), July 1994.  
         [0018]     PPP is comprised of three main components, a method for encapsulating multi-protocol datagrams, an LCP for establishing, configuring, and testing the data-link connection and a family of Network Control Protocols (NCPs) for establishing and configuring different network-layer protocols.  
         [0019]     The IETF RFC 1661 defines three classes of LCP packets, namely Link Configuration packets used to establish and configure a link, Link Termination packets used to terminate a link and Link Maintenance packets used to manage and debug a link. Each of these packets comprises a code field, an identifier field, a length field and a data field of zero or more octets. The format of the data field is determined by the code field, and the length of the data field is indicated in the length field. While the content of the data field is defined for Link Configuration packets and Link Maintenance packets, it may contain any data for use by the sender in the case of Link Termination packets. This data may consist of any binary value and is thus suited to comprise as well cause values provided by a mobile communication network.  
         [0020]     The invention can be employed for example with a GPRS capable mobile terminal, but equally with any other mobile terminal which enables terminal equipment to access a mobile communication network. The invention can further be employed for any terminal equipment which is able to establish a connection to a mobile communication network via a mobile terminal, for example a PDA or a PC.  
         [0021]     The invention can be realized in particular, though not exclusively, by a software running in the processing component of the mobile terminal and of the terminal equipment, respectively.  
         [0022]     Other objects and features of the present invention will become apparent from the following detailed description considered in conjunction with the accompanying drawings. It is to be understood, however, that the drawings are designed solely for purposes of illustration and not as a definition of the limits of the invention, for which reference should be made to the appended claims. It should be further understood that the drawings are not drawn to scale and that they are merely intended to conceptually illustrate the structures and procedures described herein. 
     
    
     BRIEF DESCRIPTION OF THE FIGURES  
       [0023]      FIG. 1  schematically shows a system in which the invention can be implemented;  
         [0024]      FIG. 2  is a flow chart illustrating an embodiment of the method according to the invention;  
         [0025]      FIG. 3  is a diagram illustrating some signaling in the embodiment of the method according to the invention; and  
         [0026]      FIG. 4  illustrates an LPC Terminate Request message format employed in the embodiment of the method according to the invention. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0027]     The invention can be implemented for example in the system depicted in  FIG. 1 . In this system, a terminal equipment  10  may access an external packet data network  20  via a mobile terminal  30  and a mobile communication network  40 .  
         [0028]     The terminal equipment  10  of the system is assumed by way of example to be a laptop computer. The laptop computer  10  comprises an external interface  11 , a display  12  as a user interface, a storing component  13  and a processing component  14 . The processing component  14  is connected to each of the external interface  11 , the display  12  and the storing component  13 . The processing component  14  is designed specifically for realizing the invention, as will become apparent further below. It is to be understood that also the processing component  14  can be composed of one or of several components, that it may comprise software and/or hardware elements for the required processing, and that it can be connected to the external interface  11 , the display  12  and the storing component  13  either directly or via further components. The laptop computer  10  comprises in addition various other components as known in the art, which are not shown in  FIG. 1 .  
         [0029]     The mobile terminal  30  of the system is assumed by way of example to be a GPRS capable mobile phone. The mobile phone  30  comprises a transceiver  31 , an external interface  32  and a processing component  33  connected to both. The processing component  33  is designed specifically for realizing the invention, as will become apparent further below. It is to be understood that the processing component  33  can be composed of one or of several components, that it may comprise software and/or hardware elements for the required processing, and that it can be connected to the transceiver  31  and to the external interface  32  either directly or via further components. The mobile phone  30  comprises in addition various other components as known in the art, which are not shown in  FIG. 1 .  
         [0030]     The mobile communication network  40  of the system is assumed by way of example to be a PLMN (Public Land Mobile Network) enabling communication in a packet switched network, e.g., GPRS. The mobile communication network  40  provides access to the external packet data network  20  in a known manner. The access to the external packet data network  20  can be used for example to request packet data for a specific service which is offered via the external packet data network  20 .  
         [0031]     The functioning of the system of  FIG. 1  will now be explained in more detail with reference to  FIGS. 2 and 3 .  FIG. 2  is a flow chart schematically illustrating the method according to the invention on the mobile side, i.e. on the side of the laptop computer  10  and the mobile phone  30 .  FIG. 3  is a modified diagram from the above mentioned specification TS 27.060, which is incorporated by reference herein. The diagram of  FIG. 3  illustrates the signaling between the laptop computer  10 , the mobile phone  30  and the mobile communication network  40  for a part of the flow chart of  FIG. 2 . All signaling between the laptop computer  10  and the mobile phone  30  is carried out via the interfaces  11 ,  32 , and the mobile phone  30  exchanges signals with the mobile communication network  40  via its transceiver  31 .  
         [0032]     When a user of the laptop computer  10  desires to access the external packet data network  20 , first a PPP link has to be established between the laptop computer  10  and the mobile phone  30 , which is represented in  FIG. 2  by a first block  201 .  
         [0033]     The signaling between the laptop computer  10  and the mobile phone  30  for establishing the PPP link is shown in more detail as steps  1  to  7  in  FIG. 3 .  
         [0034]     In step  1 , the processing component  14  of the laptop computer  10  sends an AT command message to the processing component  33  of the mobile phone  30  in order to set up parameters and to enter a PPP mode. The processing component  33  of the mobile phone  30  responds with an AT response message in step  2 . For establishing the PPP link between the laptop computer  10  and the mobile phone  30 , a PPP in the processing component  14  of the laptop computer  10  then sends an LCP Configure-Request message to the processing component  33  of the mobile phone  30  in step  3 . In step  4 , the processing component  33  of the mobile phone  30  returns an LCP Configure-Ack message to the processing component  14  of the laptop computer  10  to confirm that the PPP link has been established.  
         [0035]     Further, a PPP in the processing component  33  of the mobile phone  30  sends an LCP Configure-Request message to the processing component  14  of the laptop computer  10  in step  5  to negotiate for the authentication protocol which is to be used for authenticating the laptop computer  10  towards the mobile phone  30 . The processing component  14  of the laptop computer  10  returns thereupon in step  6  an LCP Configure-Ack message to the processing component  33  of the mobile phone  30  to confirm the use of the specified authentication protocol. If the negotiated authentication protocol is either CHAP (Challenge Handshake Authentication Protocol) or PAP (Password Authentication Protocol), the laptop computer  10  authenticates itself towards the mobile phone  30  by means of this protocol in step  7 .  
         [0036]     Once the PPP link is established, a PDP (Packet Data Protocol) context has to be activated between the mobile phone  30  and the mobile communication network  40 , which is represented in  FIG. 2  by block  202 .  
         [0037]     The signaling between the laptop computer  10 , the mobile phone  30  and the mobile communication network  40  for the activation of the PDP context is shown as steps  8  to  10  in  FIG. 3 .  
         [0038]     In step  8 , the PPP in the processing component  14  of the laptop computer  10  sends an IPCP (Internet Protocol Control Protocol) Configure-Request message to the processing component  33  of the mobile phone  30  for activating the IP protocol. The IPCP constitutes a selected NCP (Network Control Protocol). This message comprises the request to establish a PDP context and all information on the service desired by the laptop computer, for example a PDP address for the desired service and user authentication information for the desired service. If the mobile phone  30  is not yet PS (Packet Switched) attached to the mobile communication network  40 , the processing component  33  of the mobile phone  30  initiates thereupon in step  9  a PS attach procedure with the mobile communication network  40 . In step  10 , the processing component  33  of the mobile phone  30  transmits a PDP Context Activation Request message to the mobile communication network  40 .  
         [0039]     In case the external packet data network  20  or the mobile communication network  40  does not accept for some reason the request to establish a PDP context, the PPP link between the laptop computer  10  and the mobile phone  30  is released again, which is represented in  FIG. 2  by block  203 . In accordance with the invention, the cause for the release is indicated to the laptop computer  10 .  
         [0040]     The signaling between the laptop computer  10 , the mobile phone  30  and the mobile communication network  40  for the rejection of the PDP context and the release of the PPP link is shown as steps  11  and  12  in  FIG. 3 .  
         [0041]     In step  11 , the mobile communication network  40  rejects the PDP context activation request by transmitting a PDP context Activate Reject message to the processing component  33  of the mobile phone  30 . The rejection message contains an eight-bit cause value indicating the reason for the failure. The cause value and its association to a specific failure cause is taken from the above mentioned specification TS 24.008. In this specification it is proposed, for example, that a mobile communication network informs a mobile terminal that a request cannot be accepted due to insufficient resources with a cause value of 26 or that a requested service was rejected by an external packet data network because a PDP address or type could not be recognized with a cause value of 28. Similarly, other cause values are defined for various other failure causes.  
         [0042]     In step  12 , the processing component  33  of the mobile phone  30  sends an LCP Terminate Request message to the processing component  14  of the laptop computer  10  which contains the same cause value as the PDP context Activate Reject message received by the mobile phone  30 .  
         [0043]     The structure of the employed LCP Terminate Request message is presented in  FIG. 4 .  
         [0044]     The LCP Terminate Request message comprises a Code-field of 10 bits, an Identifier-field of 7 bits, a Length-field of 15 bits, and a Cause-field of 8 bits. The structure of the LCP Terminate Request message thus corresponds to the structure of the LCP Terminate Request message defined in the above mentioned RFC 1661, except that the Data-field is defined as Cause-field. The value in the Code-field is set to “5”, as defined in the RFC 1661 for a Terminate Request message. The value in the Identifier-field is set component  14  of the laptop computer  10  in a PPP log file in the storing component  13 . Thus, also the LCP Terminate Request message comprising the cause value is stored in the PPP log file, as represented in  FIG. 2  by block  205 .  
         [0045]     In case the external packet data network  20  and the mobile communication network  40  accept the PDP context Activate Request represented by block  202  in  FIG. 2 , the PDP context is established between\rtl\i\e mobi\l\Fp\hbne  30  and the mobile communication network  40 , as represented by block  206  in  FIG. 2 . The processing component  33  of the mobile phone  30  informs the laptop computer  10  that the IP protocol is activated by sending an IPCP Configure-Ack message to the processing component  14  of the laptop computer  10 . Now, the packet data of a desired service may be delivered by the external packet data network  20  via the mobile communication network  40  to the mobile phone  30  using the established PDP context and further to the laptop computer  10  using the PPP link in a known manner. This is indicated in  FIG. 2  by block  207 .  
         [0046]     When all packet data belonging to the desired service has been transmitted successfully, the PDP context and the PPP link are released again in a known manner. This is indicated in  FIG. 2  by block  208 .  
         [0047]     If, however, there is some failure during the transmission of the packet data, the established PDP context is released by the mobile communication network  40  and the processing component  33  of the mobile phone  30  is informed about the cause of the failure in a known manner with a cause value as defined in the above mentioned specification TS 24.008. The processing component  33  of the mobile phone  30  releases thereupon as well the PPP link to the laptop computer  10  by transmitting an LCP Terminate Request message to the laptop computer  10 , as indicated in  FIG. 2  by block  209 . The LCP Terminate Request message has again the structure depicted in  FIG. 4  and comprises in the Cause-field the cause value provided by the mobile communication network  40 .  
         [0048]     As in the case of an initial failure, the processing component  14  of the laptop computer  10  extracts the cause value from the received LCP Terminate Request message, retrieves an associated textual error message from the storing component  13  and presents the retrieved textual error message on the display  12  of the laptop computer  10 , as represented in  FIG. 2  by block  210 . Further, the LCP Terminate Request message comprising the cause value is stored in the PPP log file, as represented in  FIG. 2  by block  211 .  
         [0049]     The user of the laptop computer  10  is thus informed directly via the display  12  of the laptop computer  10  about any failure causes. This has the advantage that the user has only to keep an eye on the laptop computer  10  for being informed comprehensively and for being able to react accordingly. Based on the cause values stored in the PPP log files of the laptop computer  10 , the failure reason can also be debugged at a later point of time.  
         [0050]     While it has been shown, described and pointed out fundamental novel features of the invention as applied to a preferred embodiment thereof, it will be understood that various omissions and substitutions and changes in the form and details of the devices and methods described may be made by those skilled in the art without departing from the spirit of the invention. For example, it is expressly intended that all combinations of those elements and/or method steps which perform substantially the same function in substantially the same way to achieve the same results are within the scope of the invention. Moreover, it should be recognized that structures and/or elements and/or method steps shown and/or described in connection with any disclosed form or embodiment of the invention may be incorporated in any other disclosed or described or suggested form or embodiment as a general matter of design choice. It is the intention, therefore, to be limited only as indicated by the scope of the claims appended hereto.