Abstract:
In the UMTS, resource reservation is provided by sending either the data object contents or the entire contents, of a QoS request in RSVP messages. The QoS request is piggybacked in PDP Context messages, and is passed transparently between MT  30  and GGSN  24  or SGSN  26.

Description:
CROSS-REFERENCE TO RELATED APPLICATION  
         [0001]    This application claims priority of European Patent Application No. 00301782.9, which was filed on Mar. 03, 2000.  
         FIELD OF THE INVENTION  
         [0002]    This invention relates to telecommunication networks operating Internet Protocol (IP), and relates especially to a method of reserving resources.  
         BACKGROUND OF THE RELATED ART  
         [0003]    In third generation (3G) telecommunications networks, such as Universal Mobile Telecommunication Systems (UMTS), broad bandwidth is provided for services such as data and multimedia in addition to voice. An obvious need is that required Quality of Service (QoS) should be provided to users but in IP networks if contention for resources is not resolved then QoS can not be guaranteed.  
           [0004]    In IP networks or the Internet in general, Resource Reservation Protocol (RSVP) is used to allow the network to reserve the resources so as to provide QoS. RSVP can be used for QoS control locally, or it may be used across IP networks. RSVP is an end-to-end protocol and is illustrated in FIG. 1.  
           [0005]    A transmitting user  10  sends to a receiving user  12  a message PATH. The PATH message carries the traffic characteristics information such as TSpecs to indicate the traffic behavior that is to sent from the user  10 .  
           [0006]    When the receiving user  12  receives the PATH message, it sends a RESV message that contains QoS request such as FlowSpecs.  
           [0007]    In practice, the transmitting and receiving users  10  and  12  can be located remotely so that PATH and RESV messages pass through several nodes in UMTS. As each node receives either of the messages, it makes the decision as to whether adequate resources in that node can be reserved. If this is possible, then the messages are relayed to the next hop for the PATH message and the previous hop for the RESV message. When the RESV message reaches the transmitting user  10 , it begins to transmit data.  
           [0008]    Periodic refresh messages are sent subsequently to maintain the QoS status at each node that has been set up.  
           [0009]    In UMTS, RSVP may be used to support those applications that use RSVP to activate the QoS control. It is proposed in TSG2#10 S2-0000131, “Processing RSVP Signalling in MT” that RSVP is supported in MTs (Mobile Terminal) for activating QoS control in UMTS. But the major drawbacks that have been envisaged are that the RSVP messages are transmitted separately across the UMTS networks and thus consume extra UMTS network resources, in particular the radio resources. In addition, it increases traffic load to the UMTS network.  
         SUMMARY OF THE INVENTION  
         [0010]    It is an object of the invention to provide a method of reserving resources in third or future generations of wireless mobile networks such as UMTS networks that has no or minimal impact on existing architecture or QoS procedures, that minimizes any extra signalling traffic associated with supporting the method, and that allows a suitable existing protocol to be used.  
           [0011]    According to the invention, in a third or future generation telecommunication network, a method of allocating resources for user traffic passing between a mobile terminal and a remote user characterized by sending at least a data object content of a quality of service request transparently between a support node associated with said remote user and said mobile terminal.  
           [0012]    Preferably the support node and/or the mobile is arranged to filter each incoming packet, to determine if that packet contains any quality of service request, and if so, to act on that request. If there is no request, the node or mobile passes on the packet.  
           [0013]    The support node may be either a Gateway GPRS Support Node or a Serving GPRS Support Node. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0014]    In the accompanying drawings,  
         [0015]    [0015]FIG. 1 illustrates the operation of RSVP. The invention will be described by way of example only with reference to FIG. 2, 3 and  4  in which:  
         [0016]    [0016]FIG. 2 illustrates the schematically the UMTS QoS architecture for the control plane;  
         [0017]    [0017]FIG. 3 illustrates the interchange of messages in the downlink direction with filtering at a GGSN; and  
         [0018]    [0018]FIG. 4 illustrates the downlink direction with filtering at a SGSN. 
     
    
     DETAILED DESCRIPTION  
       [0019]    In FIG. 2 the UMTS  20  comprises a Core Network (CN)  22  formed by Gateway  24  and a CN Edge  26  and a UMTS Terrestrial Radio Access Network (UTRAN)  28 . A Mobile Terminal (MT)  30  communicates with the UTRAN  28  across adio interface. The MT  30  is UMTS specific and is connected to Terminal Equipment (TE)  32  that may run non-UMTS specific applications.  
         [0020]    The Gateway  24  can communicate with External Network  40 .  
         [0021]    Each illustrated component has sub-components which are not further described.  
         [0022]    The UMTS  20  operates the application-specific Packet Data Protocol (PDP) Context as usual to negotiate the QoS and activate the QoS control between the MT  30  and UMTS network  20 .  
         [0023]    In FIG. 3, the CN Edge is now termed Serving GPRS Support Node (SGSN)  26  and the Gateway is now termed Gateway GPRS Support Node (GGSN)  24 .  
         [0024]    In the inventive method, the RSVP messages are “piggybacked” to the PDP Context messages. FIG. 3 illustrates RSVP activated QoS control in the downlink direction.  
         [0025]    The RSVP session is used end-to-end and terminated at the MT  30  and the GGSN  24 . The assumption is that the TE  32  intends to set up RSVP session with its remote peer (not shown) that also uses RSVP signaling in the external network.  
         [0026]    In general, the MT  30  and the GGSN  24  filter each incoming packet to determine if there is any QoS content; if so, the MT or GGSN processes the request; if not, the packet is passed to the next hop.  
         [0027]    When the MT  30  receives the PATH message from TE  32 , MT  30  checks to see if a PDP context exists for this RSVP session. If it does, the MT triggers the Modify/Create Secondary PDP context message if there is a change in QoS parameters or if a secondary PDP context needs to be created. The PATH message is piggybacked on the Activate/Modify PDP context Request messages using the PDP configuration option.  
         [0028]    The MT is expected to populate the Requested QoS IE (Information Element) based on the PATH information. SGSN  26  can use the information within the Requested QoS IE to do RAB (Radio Access Barrier) negotiation with UTRAN  28 . The PATH message will be relayed to GGSN  24 . The GGSN extracts the PATH message and then relays it to the external network.  
         [0029]    The GGSN can generate the PDP context response without waiting for the RESV message. However, with that approach, GGSN may not be able to populate the Negotiated QoS IE with values that matches RESV QoS requirements. FIG. 3 shows that the GGSN waits for RESV before generating the PDP context response message.  
         [0030]    When the RESV response from the remote peer is received at the GGSN  24 , it uses this information, along with relevant local configuration, to see if QoS Negotiated is the same as QoS Requested. Then it piggybacks the RESV message on the Activate/Modify PDP Context response message using the PDP config. option. RAB renegotiation can take place between SGSN and UTRAN if QoS Negotiated is different from QoS Requested. Finally the RESV message possibly adapted at the GGSN is sent on to the TE  32  by piggybacking on the Activate/Modify -PDP Context Confirmation message(s).  
         [0031]    In FIG. 4, the RSVP and PATH messages are terminated at SGSN  26  instead of the GGSN  24 .  
         [0032]    This arrangement allows fast intra-GGSN handoff when the mobile only roams between different SGSNs without changing its GGSN. In this way, the processing and RSVP signalling traffic is limited within the SGSNs with which the mobile is associated; this is achieved without increasing the traffic load or the control complexity at the GGSN serving as the gateway. Such a gateway is usually traffic-intensive and handles different signalling and traffic interworking functions between the UMTS and the external network  40 .  
         [0033]    The MT  30  and the SGSN  26  and GGSN  24  are also required to check if RSVP messages are a) sent/received for the first time, so as to initiate PDP Context set-up if appropriate; b) modified, in order to initiate PD Context Modification procedure if appropriate; or c) merely refresh messages to trigger local generation of response, in which case no action is taken.  
         [0034]    The MT  30  and SGSN  26  or GGSN  24  must also check if the RSVP messages are a) sent/received for the first time, so as to initiate the PDP context set up; b) modified, in order to initiate the PD modification process or c) merely refresh messages to trigger local generation of response.  
         [0035]    This proposed piggybacking of RSVP messages/Traffic &amp;QoS Data Objects on PDP Context control messages aims to speed up the end-to-end QoS negotiation process and minimizes the extra traffic load on the network, in particular, over the air interface.  
         [0036]    An alternative solution is to extract the Traffic Specs such as the Tspec, ADSpec from the PATH message and piggyback them using the PDP configuration option to the Activate/Modify PDP Context Request messages.  
         [0037]    In these circumstances the GGSN or SGSN can determine if it is a PATH message or a RESV messages or other RSVP messages carried by secondary PDP context by looking for the header information. A special flag is provided on QoS data objects. There are at most twelve such objects, so a flag occupies at most half a byte; a single byte can accommodate a PATH message and a RESV message.