Abstract:
A method of handling traffic flows across a network wherein each traffic flow is associated with at least one flow treatment attribute determining the flow treatment requirement for that traffic flow and wherein the network comprises at least one user terminal, at least one radio network node with means for establishing a radio communication channel between said user terminal and said radio network node and at least one packet network node with means for establishing a packet communication channel in the network, the method comprising: issuing a request for establishing a first communication pathway end to end over the network, said communications pathway including said radio communication channel and said packet communication channel, said request identifying multiple traffic flows with their associated attributes; identifying any of said traffic flows which require a different flow treatment across the network; and establishing said first communication pathway, and at least one second communication pathway end to end over the network, said second communication pathway providing a different flow treatment.

Description:
FIELD OF THE INVENTION  
         [0001]    The present invention relates to the handling of traffic flows in a mobile communications network, and in particular in a network which has access to an external packet data network such as the internet or any other packet-based system.  
         BACKGROUND OF THE INVENTION  
         [0002]    Mobile communications systems refers generally to any telecommunications systems which enable a wireless communication when users are moving within the service area of the system. A typical mobile communications systems is a Public Land Mobile Network (PLMN).  
           [0003]    Often the mobile communications network is an access network providing a user with a wireless access to external networks, hosts, or services offered by specific service providers. The user must have a subscribership with the mobile communications system in order to be able to use the services of the mobile system. Normally, in addition to the mobile subscribership, a separate subscribership is needed with each one of the other service providers whose services are accessed through the mobile communications network. The mobile subscriber data of the user may indicate which external service the user is authorized to use and to which access point or gateway node the service request should be routed. The access point or gateway node then provides further access to an external network or an external host. In this case the service request is routed on the basis of a service definition in the mobile subscriber data stored by a mobile network operator, and therefore there is no need for further authentication of the user by the gateway or the service provider.  
           [0004]    It is, however, desirable that the user is able to select the service provider or the most suitable access point of the service provider. For example, the use of the TCP/IP (Transmission Control Protocol/Internet Protocol) data network, i.e. the Internet network has increased very rapidly. Before the user can connect to the Internet, he has to have a contract with an Internet service provider ISP, who provides access to the Internet via one or more Internet access points IAP.  
           [0005]    The general packet radio service GPRS is a new service in the GSM system, and is one of the objects of the standardization work of the GSM phase 2+ at ETSI (European Telecommunication Standard Institute). The GPRS operation environment comprises one or more subnetwork service areas, which are interconnected by a GPRS backbone network. A subnetwork comprises a number of packet data service nodes SN, which in this application will be referred to as serving GPRS support nodes SGSN, each of which is connected to the SM mobile communication network (typically to base station systems by way of radio network controllers (RNC)) in such a way that it can provide a packet service for mobile data terminals via several base stations, i.e. cells. The intermediate mobile communication network provides packet-switched data transmission between a support node and mobile data terminals. Different subnetworks are in turn connected to an external data network, e.g. to a public switched data network PSPDN, via GPRS gateway support nodes GGSN. The GPRS services thus allows to provide packet data transmission between mobile data terminals and external data networks when the GSM network functions as an access network.  
           [0006]    In GPRS network the mobile station MS may optionally indicate, in a message requesting to activate a packet data protocol (PDP) context in the network, an access point name for selection of a reference point to a certain external network. A Serving GPRS support node SGSN authenticates the mobile user and sends a PDP context creation request to a gateway node GGSN selected according to a GGSN address stored in the subscriber data or according to the access point name given by the MS, or to default GGSN known by the GGSN.  
           [0007]    In such a network, a packet data protocol (PDP) context is established to carry traffic flows over the network, each PDP context including a radio bearer provided between the user equipment and the radio network controller, a radio access bearer provided between the user equipment, the radio network controller and the SGSN, and switched packet data channels provided between the serving GPRS service node and the gateway GPRS service node. Each PDP context can carry more than one traffic flow, but all traffic flows within one particular PDP context are treated the same way as regards their transmission across the network. The PDP context treatment requirement is based on PDP context treatment attributes associated with the traffic flows, for example quality of service and/or charging attributes.  
           [0008]    Currently, if a traffic flow is identified as needing a different flow treatment, this can be achieved by the user equipment (UE) generating a request for a secondary PDP context over the network. Currently, such a request can only be initiated by the UE, and cannot be determined by the network itself. There are business models that require intelligence in the network or at the application side to define the end to end (e2e) or local treatment of traffic related to certain applications. At present, these business models cannot be readily implemented.  
         SUMMARY OF THE INVENTION  
         [0009]    According to one aspect of the invention there is provided a method of handling traffic flows across a network wherein each traffic flow is associated with at least one flow treatment attribute determining the flow treatment requirement for that traffic flow and wherein the network comprises at least one user terminal, at least one radio network node with means for establishing a radio communication channel between said user terminal and said radio network node and at least one packet network node with means for establishing a packet communication channel in the network, the method comprising: issuing a request for establishing a first communication pathway end to end over the network, said communications pathway including said radio communication channel and said packet communication channel, said request identifying multiple traffic flows with their associated attributes; identifying any of said traffic flows which require a different flow treatment across the network; and establishing said first communication pathway, and at least one second communication pathway end to end over the network said second communication pathway providing a different flow treatment.  
           [0010]    Preferably, the step of identifying traffic flows with different treatment is based on their associated attributes.  
           [0011]    Another aspect of the invention provides a communications network for handling traffic flow, wherein each traffic flow is associated with at least one flow treatment attribute determining the flow treatment requirement for that traffic flow, the network comprising at least one user terminal, at least one radio network node with means for establishing a radio communication channel between said user terminal and said radio network node, and at least one packet network node with means for establishing a packet communication channel, wherein: the user terminal or the packet network node is configured to issue a request for establishing a first communication pathway end to end over the network, said communication pathway including said radio communication channel and said packet communication channel, said request identifying multiple traffic flows with their associated attributes; the network comprising means for identifying any of said traffic flows which require a different flow treatment across the network; and means for establishing said first communication pathway and at least one second communication pathway end to end over the network, said second communication pathway providing a different flow treatment.  
           [0012]    According to the following described embodiments, a policy control function node in the network, or a local policy decision point of a GGSN node in the network makes a decision where a flow of a PDP context should get different treatment e2e over the network.  
           [0013]    In a first embodiment, if it is identified that flow should get different treatment, the policy control function node (or local policy decision point of the GGSN node) causes the GGSN node to initiate network requested secondary PDP context activation. The decision is based on flow treatment attributes defined with the traffic flows in the PDP context.  
           [0014]    Once a secondary PDP context is established, all UMTS nodes in the network can treat the PDP context as a whole and therefore there is no need to implement flow-based functions in individual network nodes. The possibility to provide such e2e different treatment over the network allows the possibility to make network resource allocation and corresponding charging decisions on an end user, service or provider basis.  
           [0015]    As an alternative to the establishment of a secondary PDP context initiated at the policy control function node or the GGSN node, in a second embodiment, the flow treatment attributes can be sent to a serving GPRS service node in the network, which then establishes multiple radio access bearers (RABs) for one PDP context.  
           [0016]    As a further alternative, in a third embodiment, a radio network controller node of the network establishes multiple radio bearers for one radio access bearer.  
           [0017]    In the following described embodiment, the policy control function node is illustrated as making a decision to determine differing treatment of flows based on flow attributes defined with the traffic flows themselves. However, it would be possible to invoke different treatment of flows by GGSN external or internal packet analysis. In the case of an external packet analysis, the information could be delivered to the GGSN by any standard or proprietary protocol, for example with RADIUS messages. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0018]    For a better understanding of the present invention and to show how the same may be carried into effect, reference will now be made by way of example to the accompanying drawings.  
         [0019]    [0019]FIG. 1 is a schematic block diagram of a communications network;  
         [0020]    [0020]FIG. 1A illustrates the architectural elements of the scheme of FIG. 1;  
         [0021]    [0021]FIG. 2 is a schematic diagram illustrating the logical semantics of communication pathways in the network;  
         [0022]    [0022]FIG. 2A is a diagram illustrating authorisation of resources at the PCF;  
         [0023]    [0023]FIG. 3 is a schematic functional diagram of a first embodiment of the invention;  
         [0024]    [0024]FIG. 4 is a schematic block diagram illustrating functionality in the policy control function node for implementing the embodiment of FIG. 3;  
         [0025]    [0025]FIG. 5 is a schematic functional diagram illustrating a second embodiment of the invention;  
         [0026]    [0026]FIG. 6 is a schematic block diagram of the functionality incorporated in the SGSN for implementing the embodiment of FIG. 5; and  
         [0027]    [0027]FIG. 7 is a schematic functional diagram of a third embodiment of the invention. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0028]    [0028]FIG. 1 illustrates the nodes of a network by way of background to the present invention. Reference numeral  2  denotes user equipment UE, for example mobile stations. User equipment UE is in communication with a radio network controller  4  via radio network channels  6  which are referred to herein as radio bearers RB. These radio network channels are set up in a mobile telecommunications network in a known manner. Each user equipment UE can have one or more radio network channel open at any one time with the radio network controller  4 , and there can of course be a number of user equipments in communication with the radio network controller by way of individual radio network channels as is well known in the art. The radio network controller is in communication with a serving GPRS support node  8  via an Iu interface  10 . The serving GPRS support node  8  communicates with a gateway GPRS support node  12  via a G n  or G p  interface  14 , which is a switched packet data interface. As is well known, the serving GPRS support node  8  and the gateway GPRS support node  12  provide support for GPRS services in the network. The gateway GPRS support node  12  is under the control of a policy decision function  18 . The policy decision function may be standalone or may be combined with an application function such as a proxy connection state control function P-CSCF  16 .  
         [0029]    [0029]FIG. 1A illustrates the relationship between the different functional entities, but with the omission of the network elements which are not involved in service-based local policy (in particular radio network controller RNC and the serving gateway support node SGSN). FIG. 1A indicates that the user equipment  2  comprises an SIP client  100 , an IPBS manager  102 , a translation mapping function  104  and a UMTSBS manager  106 . The UMTSBS manager  106  is in connection with the GGSN  12  by way of its own UMTSBS manager  108 . The GGSN  12  also includes a translation mapping function and an IPBS manager  112  with a policy enforcement point. The policy enforcement point is in connection with the policy control function  18  forming part of the P-CSCF node in one embodiment.  
         [0030]    The communications semantics across the nodes of the network illustrated in FIG. 1 are shown in FIG. 2. Overall communication between user equipment  2  and the gateway GPRS support node  12  is provided by a packet data protocol (PDP) context. Each PDP context provides a communication pathway between a particular user equipment  2  and the gateway GPRS support node  12  and, once established, can carry multiple flows. Each flow represents for example a particular service or a media component of a particular service. The PDP context therefore represents a logical communication pathway for one or more flow across the network. To implement the PDP context between user equipment  2  and the serving GPRS support node  8 , radio access bearers RAB are established which allow for data transfer across the radio bearer  6  and the Iu interface  10 . The physical channels established between the user equipment  2  and the radio network controller  4  are referred to as radio bearers RB. The implementation of these logical and physical channels is known and is therefore not discussed further herein.  
         [0031]    In existing systems, multiple flows within a PDP context are all treated in the same manner based on PDP context attributes, such as quality of service (QoS) or charging treatment. The possibility exists to create a secondary PDP context at the user equipment so that certain flows from the user equipment can be treated differently in their transmission across the network. For example, there are a number of quality of service traffic classes applying to flows of differing kinds: conversational, streaming, interactive and background. Depending on the nature of the data to be transmitted across the network, the appropriate quality of service is requested by the user equipment  2  and is authorized by the network.  
         [0032]    By way of background, reference is made to FIG. 2A which is a schematic diagram illustrating the authorisation of QoS resources at an originating PCF.  
         [0033]    The PCF  18  obtains SDP parameters defined by the originator and identifies the connection information needed (for example IP address of the downlink media flow, media ports to be used etc.). The PCF  18  obtains the negotiated SDP parameters from the terminating side through an SIP signalling interaction. The PCF  18  then identifies the connection information needed to define the uplink connection. SDP parameters are used by the PCF  18  in order to define the QoS resource authorisation. The PCF  18  authorises each media component negotiated for the session which is expressed in terms of IP QoS parameters. An authorisation token is generated by the PCF and sent to the UE.  
         [0034]    There follows a description of techniques which allow for differing treatment of flows based on intelligence in the network.  
         [0035]    [0035]FIG. 3 is a schematic diagram illustrating a first embodiment in which two PDP contexts are created by the policy decision function PDF  18  dependent on the nature of the flows.  
         [0036]    The user equipment  2  generates (step S 1 ) a request for activating a PDP context across the network. The request includes an authorisation token and, in this embodiment, three traffic flow identifiers Flow 1 , Flow 2  and Flow 3 . This request is carried from the user equipment UE to the serving GPRS support node SGSN. The SGSN  8  creates (step S 2 ) a PDP context request for transmission to the GGSN  12 , which itself creates (step S 3 ) a request to the policy decision function PDF  18 . The policy decision function  18  determines (step S 4 ) the treatment required for each flow, and in particular establishes whether any of the flows should be treated differently. A decision (step S 5 ) is returned from the policy decision function  18  to the GGSN  12  defining a packet classifier for each flow to identify the flow in the network, the attributes of each of the flows, Flow 1 , Flow 2  and Flow 3  and also determining that a different treatment is required for Flow 3 . The GGSN  12  then creates a PDP context response (step S 6 ) which identifies the fact that a different treatment is required for Flow 3 . The GGSN may indicate this fact implicitly (e.g. by indicating the flows Flow 1  and Flow 2  accepted for the PDP context) or explicitly (e.g. by indicating that the flow Flow 3  requires a different treatment). The SGSN  8  acknowledges (step S 7 ) the PDP context acceptance to the user equipment  2 , establishing the PDP context for Flow 1  and Flow 2 , and identifying Flow 3  as needing different treatment. In addition, the GGSN  12  initiates network requested secondary PDP context activation by establishing (step S 8 ) a PDU (protocol data unit) request identifying the Flow 3  attributes to the SGSN  8 . The SGSN  8  responds (step S 9 ) by returning a PDU response to the GGSN, which can then optionally report back to the policy decision function  18  the fact that the network requested secondary PDP context activation was initiated. The SGSN then also requests (step S 10 ) a secondary PDP context activation in relation to the attributes and packet classifiers for Flow 3  to the user equipment UE. The user equipment UE then goes through the PDP context establishment process again (step S 11 ) to create a further secondary PDP context according to steps S 1  to S 7  as illustrated in FIG. 3. At this phase, steps S 3  to S 5  are not required. When the secondary PDP context is activated, the GGSN can optionally report to the policy decision function  18  the fact that the secondary PDP context is successfully activated.  
         [0037]    This technique allows for the GGSN under the control of the policy decision function  18  to request a further PDP context establishment for the flow (in this case Flow 3 ) requiring different treatment. It is of course possible that multiple network requested secondary PDP context activation procedures are established. This is the case e.g. if all flows Flow 1 , Flow 2  and Flow 3  require different treatment.  
         [0038]    It will be appreciated that in order to implement the functionality explained above with reference to FIG. 3, the policy decision function  18  incorporates the functionality illustrated in FIG. 4. That is, it includes a block  20  for reading the attributes on incoming flows, a block  22  for identifying the difference between the attributes and a block  24  for reporting the flow attributes and identifying any different treatment required. These functional blocks can be implemented in any suitable way, and most probably will be implemented by a suitably programmed processor or other software/hardware combination.  
         [0039]    The functional blocks referred to above and illustrated in FIG. 4 could as an alternative be implemented at the GGSN  12  itself, without the need for a separate PDF block.  
         [0040]    A second embodiment of the invention is illustrated in FIG. 5. According to this embodiment, steps S 1  to S 6  are the same as described above with reference to FIG. 3. In this case however, instead of causing the user equipment  2  to create a further PDP context as in step  11  of FIG. 3, the SGSN  8  is caused (step S′ 8 ) to establish multiple radio access bearers with different attributes to accommodate the different treatment required for Flow 3 . To achieve this, a packet classifier and the attributes of each of the flows are supplied to the SGSN  8  from the GGSN  12 . In the example given, a first radio access bearer RAB 1  is established for Flow 1  and Flow 2  and a second radio access bearer RAB 2  is established for Flow 3 . The SGSN  8  identifies traffic flows with packet classifiers and can classify traffic flows to the correct radio access bearers. At step S′ 9  a PDP context activation acceptance is generated by the SGSN.  
         [0041]    In order to implement the technique of FIG. 5, the SGSN  8  incorporates the functionality illustrated in FIG. 6 in the form of the following functional blocks. When the radio access bearers are created, the SGSN  8  requests as many radio access bearers as there are different treatments, as indicated schematically in the block generate RABs  26 . Then, when traffic starts flowing, the SGSN  8  identifies a traffic flow with a packet classifier in a mapping function  28  and maps that traffic flow into the correct radio access bearer which is then used when the SGSN  8  forwards traffic towards the user equipment UE.  
         [0042]    The user equipment UE is informed which traffic flows are carried on which radio access bearers. In the example given, the user equipment UE receives flow specific packet classifiers and flow attributes for RAB 1  and RAB 2 . This way, the user equipment UE knows that RAB 1  carries Flow 1  and Flow 2  and RAB 2  carries Flow 3  and thus the user equipment UE can send traffic to the network on the correct radio access bearers. The user equipment UE identifies traffic flows with packet classifiers.  
         [0043]    [0043]FIG. 7 illustrates a third embodiment of the invention. In FIG. 7, steps S 1  to S 6  are the same as described above with reference to FIGS. 3 and 5. In this case however, instead of establishing multiple RABs, the SGSN  8  establishes step S″ 8 ) a single radio access bearer RAB which identifies a packet classifier and the flow attributes of each of the flows and also identifies the fact that a different treatment is required for Flow 3 . At the radio network controller  4 , multiple radio bearers are established (step S″ 9 ) to take into account the differing treatments required as identified in the RAB establishment request. That is, according to step S″ 9  illustrated in FIG. 7, radio bearer RB 1  is established to carry Flow 1  and Flow 2  and radio bearer RB 2  is established to carry Flow 3 . The radio network controller  4  identifies traffic flows with packet classifiers and can classify traffic flows to the correct radio bearers. An RAB establishment response is returned from the radio network controller to SGSN  8  (step S″ 10 ).  
         [0044]    The user equipment UE is informed which traffic flows are carried on which radio bearers. In the example given, the user equipment UE receives flow specific packet classifiers and flow attributes for RB 1  and RB 2 . This way, the user equipment UE knows that RB 1  carries Flow 1  and Flow 2  and RB 2  carries Flow 3  and thus the user equipment UE can send traffic to the network on the correct radio bearers. The user equipment UE identifies traffic flows with packet classifiers.  
         [0045]    It shall be appreciated that although the above described user equipment UE initiated establishment of pathways, the establishment process may also be initiated by the network. For example, the GGSN may initiate the PDP context establishment by issuing a request for such.