Abstract:
At present some situations occur where a policy control at individual user level is not enough. For example, where a plurality of users surpasses a load limit in a certain location area, which could imply a risk of network congestion, policy control decisions in conventional architectures have to be made by submitting corresponding orders for each user affected by the decision, thus resulting in a higher signalling and processing load. To overcome these drawbacks, the present specification provides for new network entities and method to monitor and control a plurality of users, as dynamically determined according to different selection criteria, in order to compile users-related aggregated reports, to establish dynamic group of users whom specific policy control rules can be applied, and to map orders and information between group and user level.

Description:
TECHNICAL FIELD 
       [0001]    The present invention relates to policy control for a Policy and Charging Control architecture. More specifically, the present invention relates to policy control mechanisms to be simultaneously triggered for a plurality of users in order to, for instance, improve network performance, save network resources, provide customizable user services, or combinations thereof. 
       BACKGROUND 
       [0002]    A currently developed Policy and Charging Control (hereinafter PCC) architecture permits to integrate both policy and charging control, whilst optimizing the information flow. 
         [0003]    The development of PCC standards is growing with different versions and, in particular, the invention is appreciably suitable for a PCC architecture in accordance with TS 23.203 (V.8.1.1) for Evolved 3GPP Packet Switched domain (wherein 3GPP stands for “3rd Generation Partnership Project”), including both 3GPP accesses (GERAN/UTRAN/E-UTRAN) and Non-3GPP accesses. 
         [0004]    Generally speaking, the PCC architecture comprises an Application Function (hereinafter AF), a Policing and Charging Rules Function (hereinafter PCRF), a Policing and Charging Enforcement Function (hereinafter PCEF) and a Subscription Profile Repository (hereinafter SPR), as illustrated in  FIG. 1 . 
         [0005]    In accordance with PCC standards, an AF is as an element offering applications the control of IP bearer resources according to what has been negotiated in the signalling layer; the AF communicates with the PCRF to transfer dynamic session information, namely description of the media to be delivered in the transport layer. The PCRF is the function providing policy and charging control for media components negotiated from a user equipment (hereinafter UE) of a user through the AF; the PCRF creates PCC rules based on the information received from the AF and to be installed in the PCEF. The PCEF encompasses service data flow detection based on filters included in the PCC rules, as well as online and offline charging interactions and policy enforcement. The SPR provides subscription information regarding quality of service (hereinafter QoS) parameters subscribed by the user such as bandwidth and others. 
         [0006]    A current PCC behaviour is exemplary illustrated in  FIG. 2  wherein a UE accesses a streaming server. In this exemplary PCC architecture, the UE connects to a streaming server and negotiates the session. During the session negotiation the IP ports used by the end points, the type of media (audio, video, etc.) and the QoS parameters are defined. Then, the streaming server provides the session information that has been negotiated to the PCRF. The PCRF checks that the session information received is in accordance with the operator defined policies, stores the service information and responds with acknowledgement to the application server. Subsequently, the PCRF sends a so-called RAR message to request that a gateway (hereinafter GW), which includes a PCEF, installs, modifies or removes PCC rules. Once a proper action has been taken with the PCC rules, the GW sends an RAA to acknowledge the previous RAR, initiates a procedure to create or update a so-called PDP context request message, and sends back to the PCRF required notifications with a so-called CCR message. Eventually, the PCRF stores the information received in said notifications and acknowledges the CCR back with a so-called CCA message. 
         [0007]    At present, an IP-Connectivity Access Network (hereinafter IP-CAN) session is the association between a UE and an IP network. This association is identified by a UE IP address together with UE identity information, if available. An IP-CAN session incorporates one or more IP-CAN bearers. Support for multiple IP-CAN bearers per IP-CAN session is IP-CAN specific. An IP-CAN session exists as long as the UE IP address is established and announced to the IP network. For the sake of simplicity, IP-CAN session may be also referred to as ‘user session’ throughout this invention disclosure. 
         [0008]    In a conventional PCC architecture, the PCRF thus receives information of each particular user session, and takes actions over each particular user session. 
         [0009]    However, in some situations, a policy control at individual user level is not enough. For example, a control of the aggregated load generated by a plurality of users in a certain location area may be essential in order to avoid network congestion. In principle, this plurality of users cannot be pre-defined since it is not known beforehand what users will be responsible for such network congestion. 
         [0010]    In situations like this, or where the plurality of users has surpassed a load limit in a certain location area, which could imply a risk of network congestion, an apparently suitable solution may be the downgrading of the quality of service for every user, or for a subset of users, in the plurality of users. However, this is not a suitable solution fitting user expectations. 
         [0011]    Nowadays, where a decision has to be taken at the PCC architecture affecting a plurality of users, a plurality of corresponding orders has to be sent for each user affected, thus resulting in a higher signalling and processing load. 
       SUMMARY 
       [0012]    The present invention is aimed to at least minimize the above drawback and provides for new network entities and method to monitor and control a plurality of users, as dynamically determined according to different selection criteria, to compile users-related aggregated reports, and to map orders and information between group and user level. 
         [0013]    In particular, for the purposes of the present invention, conventional network nodes or devices of a PCC architecture, such as PCRF, PCEF, or AF, may be replaced by simpler network nodes or devices with a reduced functionality, as compared with the ones specified in the corresponding technical specifications, and inasmuch as said simpler network nodes or devices fulfil the expectations of the invention. For instance, a simpler and lighter policy enforcement device may replace and enhance a conventional PCEF of a PCC architecture and a simpler and lighter policy decision server may replace and enhance a conventional PCRF of the PCC architecture. Nevertheless, the conventional PCEF and PCRF of the PCC architecture may as well be enhanced to incorporate the features disclosed throughout the present specification thus offering similar advantages. 
         [0014]    In accordance with a first aspect of the present invention, there is provided a new method of handling and controlling resources in the bearer plane for a plurality of users. 
         [0015]    This method comprises the steps of: indicating from a policy enforcement device, in particular a PCEF, towards a policy decision server, in particular a PCRF, the establishment of a session for a user through an IP Connectivity Access Network (hereinafter IP-CAN session); generating at the policy decision server a user session for said user, and policy control rules, in particular PCC rules as described in PCC specifications, applicable to said user session; determining, at the policy decision server, at least one criterion to monitor this user along with other users in a group of users; associating, at the policy decision server, the user session for the user with a group session for the at least one criterion; determining, at the policy decision server, policy control rules applicable to said group session; downloading from the policy decision server towards the policy enforcement device the policy control rules applicable to said user session and the policy control rules applicable to said group session, and indicating respective events to be reported; installing the received policy control rules and associating the IP-CAN session with the group session at the policy enforcement device; and applying at the policy enforcement device the policy control rules applicable to the group session to all IP-CAN sessions associated with the group session. 
         [0016]    Since in this method information about the group session is exchanged between the policy decision server and the policy enforcement device, the group session may advantageously be identified by a session group identifier. 
         [0017]    On the other hand, a user session for a user may be associated with more than one group session. In other words, a user may be monitored along with more than one group of users. 
         [0018]    Generally speaking, this method is advantageous to take actions at a group level as a response to certain events. To this end, responsive to an event, the method may further comprise a step of submitting from the policy decision server towards the policy enforcement device an indication to either confirm, or modify, or terminate or replace the current policy control rules for the group session. 
         [0019]    In this respect, the event to be responded may be an event selected from: events triggered from the policy enforcement device; internal events detected at the policy decision server; and events notified to the policy decision server from an external entity such as a provisioning system, an AF device, or both. 
         [0020]    In an embodiment of the invention, the needs for creating the group session is determined by the policy decision server, which thus indicates it to the policy enforcement device, but it is the latter the one creating the group session and informing the former. Where this embodiment is preferred, the step of determining in this method at least one criterion to monitor this user with other users in a group includes a step of notifying the at least one criterion towards the policy enforcement device; a step of generating a new group session at the policy enforcement device; a step of receiving from the policy enforcement device an identifier of a session group for the group session; and, where the identifier of the session group identifies a new group session, a step of generating at the policy decision server policy control rules applicable to the new group session. 
         [0021]    In another embodiment of the invention, both the needs for creating the group session as well as the creation of the group session are carried out at the policy decision server. Where this embodiment is the preferred one, the step of associating the user session for the user with a group session may include a step of generating a new group session at the policy decision server for the at least one criterion, and a step of generating policy control rules applicable to the new group session. Alternatively in this embodiment, where a new group session is not necessary, the step of associating the user session for the user with a group session may include a step of determining an already existing group session for the at least one criterion. 
         [0022]    Generally speaking for this method, the at least one criterion to monitor the user with the group of users may be selected from a plurality of criteria including: type of subscription, location area, service usage, corporate users, and combinations thereof. 
         [0023]    In particular, the criterion related to type of subscription may include an indication of ordinal importance of the subscription, wherein this ordinal importance may further include an indicator selected from: first class or “gold”, second class or “silver”, or third class or “bronze”. 
         [0024]    Also in particular, the criterion related to location area may include at least one indication selected from: a radio network area where the user is roaming, and an area with high congestion. Advantageously, the radio network area may correspond to an area requiring a special treatment in terms of QoS, access, charging, contents insertion, etc, such as airports or shopping centres; or the radio network area may correspond to a location area corresponding to a country region where a service may be tailored according to region particularities, such as a particular language. 
         [0025]    Moreover, the criterion related to service usage may include an indication of the type of service, this indication selected from: peer-to-peer service, end-to-end service, downloading, uploading and location-based-service. Generally speaking, resource intensive applications that require monitoring of service usage. 
         [0026]    Furthermore, the criterion related to corporate users may include an identifier of a Virtual Private Network where the user is connected to. 
         [0027]    In accordance with a second aspect of the present invention, there is provided a policy decision server suitable for acting as, or for replacing, a PCRF of a PCC architecture, for providing network control of service data flows by making policy control decisions per user and service basis and by downloading corresponding policy control rules, such as PCC rules, towards a policy enforcement device; this policy enforcement device being suitable for acting as, or for replacing, a PCEF of a PCC architecture and in charge of handling and controlling resources in the bearer plane for a plurality of users. 
         [0028]    This policy decision server includes: an input unit for receiving an indication from a policy enforcement device indicating the establishment of a session for a user through an IP Connectivity Access Network, namely an IP-CAN session; a generator for generating a user session for said user, and policy control rules applicable to said user session; an output unit for downloading towards the policy enforcement device the policy control rules applicable to said user session, and for indicating corresponding events to be reported; a processing unit for determining at least one criterion to monitor this user along with other users in a group of users, for associating the user session for the user with a group session for the at least one criterion, and for determining policy control rules applicable to said group session; and wherein the output unit is arranged for downloading towards the policy enforcement device the policy control rules applicable to said group session, and for indicating corresponding events to be reported. 
         [0029]    In order to advantageously take actions at a group level as a response to certain events, thus aligned with the above method, the output unit of this policy decision server may be arranged for submitting towards the policy enforcement device, responsive to an event, an indication to either confirm, or modify, or terminate or replace the current policy control rules for the group session. 
         [0030]    As for the above method, and for the embodiment where the policy enforcement device is in charge of creating the group session, the output unit of the policy decision server may be arranged for notifying the at least one criterion towards the policy enforcement device, and the input unit of the policy decision server may be arranged for receiving from the policy enforcement device an identifier of a session group for the at least one criterion. Also for this embodiment, the processing unit may cooperate with the generator at the policy decision server and, where the identifier of the session group identifies a new group session, the generator may be arranged for generating policy control rules applicable to the new group session. 
         [0031]    Also as for the above method, and for the embodiment where the policy decision server is in charge of creating the group session, the generator of the policy decision server may further be arranged for generating a new group session for the at least one criterion, and for generating policy control rules applicable to the new group session. 
         [0032]    Advantageous for both embodiments, the processing unit of the policy decision server may further be arranged for determining an already existing group session for the at least one criterion. 
         [0033]    Moreover, aligned with the above method and with corresponding technical features, the processing unit of the policy decision server may further be arranged to handle criteria to monitor the user with the group of users, the criteria selected from: type of subscription, location area, service usage, corporate users, and combinations thereof. 
         [0034]    In accordance with a third aspect of the present invention, there is provided a policy enforcement device suitable for acting as, or for replacing, a PCEF of a PCC architecture, for installing policy control rules, such as PCC rules, received from a policy decision server in order to handle and control resources in the bearer plane for a plurality of users; this policy decision server being suitable for acting as, or for replacing, a PCRF of a PCC architecture as stated above. 
         [0035]    This policy enforcement device comprises: a first input unit cooperating with a processing unit for establishing a session for a user through an IP Connectivity Access Network, namely an IP-CAN session; an output unit for indicating towards a policy decision server the establishment of the IP-CAN session for the user; a second input unit arranged for downloading from the policy decision server first policy control rules applicable to the user session and second policy control rules applicable to a given group session, as well as indications of respective events to be reported; and wherein the processing unit is arranged for installing the first and second policy control rules, for associating the IP-CAN session with the group session, and for applying the second policy control rules applicable to the group session to all IP-CAN sessions associated with the group session. Optionally, said first and second input units may be provided as separate input units or as an integral input unit. 
         [0036]    Aligned with the advantageous actions to be taken, as stated above, at a group level as a response to certain events, the output unit of the policy enforcement device may be arranged for reporting the respective events, upon detection by the processing unit. 
         [0037]    For the sake of an additional flexibility to act on the policy control rules installed for the group session, the input unit of the policy enforcement device may be arranged for receiving an indication from the policy decision server to either confirm, or modify, or terminate or replace the current second policy control rules applicable for the group session. 
         [0038]    Moreover, aligned with the above method, and for the embodiment where the policy enforcement device is in charge of creating the group session, the input unit of the policy enforcement device may be arranged for receiving a notification from the policy decision server indicating at least one criterion to monitor the user along with other users in a group of users, the processing unit of the policy enforcement device may be arranged for assigning a group session for the at least one criterion to monitor the user, and the output unit of the policy enforcement device may be arranged for submitting towards the policy decision server an identifier of the session group. 
         [0039]    On the other hand, the invention may be practised by a computer program, in accordance with a fourth aspect of the invention, the computer program being loadable into an internal memory of a computer with input and output units as well as with a processing unit, and comprising executable code adapted to carry out the above method steps. In particular, this executable code may be recorded in a carrier readable in the computer. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0040]    The features, objects and advantages of the invention will become apparent by reading this description in conjunction with the accompanying drawings, in which: 
           [0041]      FIG. 1  basically represents a conventional model of entities involved in PCC architecture. 
           [0042]      FIG. 2  shows a conventional sequence of actions carried out where a user with user equipment exemplary accesses a streaming server in a scenario with PCC architecture. 
           [0043]      FIG. 3  shows an exemplary relationship of user session data and group session data in a PCRF and PCEF as well as interfaces involved between PCRF and input for group monitoring and between PCRF and PCEF. 
           [0044]      FIG. 4  illustrates a sequence of actions to be performed in accordance with the invention to carry out a method of handling and controlling resources in the bearer plane for a plurality of users. 
           [0045]      FIG. 5  illustrates a first sequence of actions to be performed on a group basis upon notification of an exemplary first event from the PCEF towards the PCRF. 
           [0046]      FIG. 6  illustrates an exemplary implementation of a policy decision server suitable for acting as, or for replacing, a PCRF of a PCC architecture, for providing network control of service data flows by making policy control decisions per user and service basis and by downloading corresponding policy control rules, such as PCC rules, towards a policy enforcement device. 
           [0047]      FIG. 7  illustrates a second sequence of actions to be performed on a group basis upon notification of an exemplary second event from the PCEF towards the PCRF. 
           [0048]      FIG. 8  illustrates a third sequence of actions to be performed on a group basis upon notification of an exemplary third event from a provisioning system towards the PCRF. 
           [0049]      FIG. 9  illustrates an exemplary implementation of a policy enforcement device suitable for acting as, or for replacing, a PCEF of a PCC architecture, for installing policy control rules, such as PCC rules, received from a policy decision server in order to handle and control resources in the bearer plane for a plurality of users. 
           [0050]      FIG. 10  illustrates a fourth sequence of actions to be performed on a group basis upon notification of an exemplary fourth event, in this case a deactivation of the IP-CAN session for the user, from the PCEF towards the PCRF. 
           [0051]      FIG. 11  illustrates a fifth sequence of actions to be performed on a group basis upon detection of an exemplary fifth event internally at the PCRF. 
           [0052]      FIG. 12  illustrates a sixth sequence of actions to be performed on a group basis upon notification of an exemplary sixth event from an AF device towards the PCRF. 
           [0053]      FIG. 13A-13B  illustrate a sequence of actions to be performed in accordance with an embodiment of the invention to carry out the method of handling and controlling resources in the bearer plane for a plurality of users. 
       
    
    
     DETAILED DESCRIPTION 
       [0054]    The following describes currently preferred embodiments of means and method of handling and controlling resources in the bearer plane for a plurality of users. 
         [0055]    In this respect,  FIG. 4  illustrates relevant sequence of actions to carry out this method of handling and controlling resources in the bearer plane for a plurality of users in accordance with an embodiment of the invention. 
         [0056]    The relevant sequence of actions illustrated in  FIG. 4  start with a step S- 150  of indicating from a PCEF  2  towards PCRF  1  the establishment of a session for a user through an IP Connectivity Access Network, namely an IP-CAN session. 
         [0057]    Upon receipt of such indication, the PCRF  1  generates during a step S- 155  a user session for the user and PCC rules to be applied at the bearer plane for IP flows corresponding to the user session; the PCRF  1  determines during a step S- 160  at least one criterion to monitor this user along with other users in a group of users; the PCRF  1  associates during a step S- 165  the user session for the user, which was generated during the step S- 155 , with a group session for the at least one criterion; and the PCRF  1  determines during a step S- 170  PCC rules applicable to the group session. 
         [0058]    In particular, the step of associating the user session for the user with the group session, under this embodiment, includes a step not illustrated in any drawing of determining whether an appropriate group session already exists for the at least one criterion. Where no group session exists for the at least one criterion, the step of associating the user session for the user with the group session also includes a step not illustrated in any drawing of generating a new group session at the PCRF  1  for the at least one criterion, and a step of generating PCC rules applicable to the new group session. On the other hand, where a group session already exists for the at least one criterion, the step of associating the user session for the user with the group session includes a step not illustrate din any drawing of determining at the PCRF  1  an already existing group session for the at least one criterion. 
         [0059]    In the embodiment illustrated in  FIG. 4 , both PCC rules to be applied for the user session and PCC rules to be applied for the group session are downloaded together during a step S- 175  towards the PCEF  2 . 
         [0060]    Upon receipt of said PCC rules, the PCEF  2  installs during a step S- 180  the PCC rules for the user session and the PCC rules for the group session. Now, the PCEF can apply during a step S- 185 , and whilst these PCC rules for the group session are valid and in force, the PCC rules for the group session to all IP-CAN sessions associated with the group session. 
         [0061]    Regarding the association of user sessions for users with group sessions at the PCRF  1 , and the association of IP-CAN sessions for users with group sessions at the PCEF  2 , an exemplary data model is illustrated in  FIG. 3  wherein a same user session for a user can be applied with one or more group session and vice verse. 
         [0062]    As shown in  FIG. 3 , where a number of user sessions  161 - 165  and another number of group sessions  171 - 172  at the PCRF are illustrated, a same user session  162  for a user may be associated with a couple of group sessions  171  and  172  at the PCRF  1 . Likewise,  FIG. 3  also illustrates a number of IP-CAN sessions  261 - 265  for users and another number of group sessions  271 - 272  at the PCEF  2 , wherein a same IP-CAN session  262  for a user may be associated with a couple of group sessions  271  and  272  at the PCEF. 
         [0063]    An alternative embodiment to the one illustrated in  FIG. 4  is disclosed in the following with reference to  FIG. 13A-14B . This alternative embodiment starts with a same step S- 150  of indicating from a PCEF  2  towards PCRF  1  the establishment of an IP-CAN session for a user, a same step S- 155  of generating at the PCRF  1  a user session for the user and PCC rules to be applied at the bearer plane, and a same step S- 160  of determining at the PCRF the at least one criterion to monitor this user along with other users in a group of users. 
         [0064]    In this alternative embodiment depicted in  FIG. 13A , instead of generating the group session at the PCRF  1 , the PCRF  1  downloads during a step S- 425  the PCC rules for the user session along with an indication to create a group session for the at least one criterion towards the PCEF  2 . 
         [0065]    The PCEF receiving the PCC rules for the user session installs during a step S- 430  such PCC rules for the user session and, aware of the indication to create a group session, either generates a group session during a step S- 435 , or determines an existing group session to be applied. Moreover, the PCEF  2  establishes a control session for the group session. 
         [0066]    Then, as illustrated in  FIG. 13B , the PCEF  2  indicates during a step S- 440  the establishment of the control session for the group session, and provides an identifier of said group session, towards the PCRF  1 . 
         [0067]    Upon receipt of the indication of establishment of the control session for the group session, the PCRF  1  associates during a step S- 445  the user session for the user therein with the group session indicated from the PCEF  2  for the at least one criterion. The PCRF  1  also determines during a step S- 450  PCC rules applicable to the group session, either by generating PCC rules applicable to a new group session received from the PCEF  2 , or by determining existing PCC rules applicable to an existing group session indicated from the PCEF  2 . 
         [0068]    Subsequently under this embodiment, the PCRF  1  downloads during a step S- 455  the PCC rules for the group session towards the PCEF  2 , and the PCEF  2  installs the received PCC rules for the group session during a step S- 460 . 
         [0069]    As for the previous embodiment, the PCEF can apply during a step S- 465 , and whilst these PCC rules for the group session are valid and in force, the PCC rules for the group session to all IP-CAN sessions associated with the group session. 
         [0070]    As already commented above, an in order to carry out the above method steps, the present invention provides for a policy decision server suitable for acting as, or for replacing, a PCRF of a PCC architecture for providing network control of service data flows, by making policy control decisions per user and service basis and by downloading corresponding policy control rules, such as PCC rules, towards a policy enforcement device. 
         [0071]    In this respect,  FIG. 6  illustrates an exemplary implementation of a PCRF  1  implementing the features included in a policy decision server in accordance with the second aspect of the invention. 
         [0072]      FIG. 6  thus shows a PCRF  1  including an input unit  42  for receiving an indication from a PCEF  2 , which in particular may be a device implemented in a Gateway  4 , indicating the establishment of an IP-CAN session for a given user; a generator  60  for generating a user session for said user, and for generating policy control rules applicable to said user session; and an output unit  41  for downloading towards the PCEF  2  the policy control rules applicable to said user session, and for indicating corresponding events to be reported. 
         [0073]    More specifically, the input unit  42  and the output unit  41  are connected with the generator  60  via a processing unit  20  in charge of controlling when the former units enter into operation as well as the required data to be exchanged between them. 
         [0074]    In particular, the input unit  42  and the output unit  41  may be provided as an integral input/out unit  40  as illustrated in  FIG. 6  though other arrangements are also possible as the one illustrated in  FIG. 9  and further commented. 
         [0075]    Apart from controlling the operation of the input unit  42 , the output unit  41  and the generator  60 , the processing unit  20  of the PCRF  1  illustrated in  FIG. 6  is also arranged for determining at least one criterion to monitor this user along with other users in a group of users, for associating the user session  162  for the user with a group session  172  for the at least one criterion, and for determining policy control rules applicable to said group session. 
         [0076]    To this end, the processing unit  20  cooperates with a storage  10  to store criteria to monitor users, the criteria received as an input for group monitoring  81  preferably from a so-called Provisioning System  8  in charge of configuring said criteria and likely other user data to be provisioned into the Subscriber Profile Repository  5  illustrated in  FIG. 1 . In particular, this Subscriber Profile Repository  5  may be implemented as external data storage, or being an integral part of the storage  10  included in the PCRF shown in  FIG. 6 . In particular, the storage  10  is connectable with the generator  60  and with the processing unit  20  directly or through each other. 
         [0077]    In order to accomplish method steps in accordance with an embodiment above, namely where the group session is created in the policy enforcement device of the gateway  4 , the output unit  41  may be arranged for notifying the at least one criterion towards the PCEF  2 , and the input unit  42  may be arranged for receiving from the PCEF  2  an identifier of a session group, which may be generated therein, for the at least one criterion. Under this embodiment, the processing unit  20  may also cooperate with the generator  60  and, where the identifier of the session group identifies a new group session, the generator may be arranged for generating policy control rules, such as PCC rules, applicable to the new group session. 
         [0078]    In order to accomplish method steps in accordance with another embodiment of the invention explained above, that is, where the group session is created at the policy decision server, the generator  60  may be further arranged for generating a new group session  172  for the at least one criterion, and for generating policy control rules applicable to said new group session. 
         [0079]    Nevertheless, an irrespective of the preferred embodiment, the processing unit  20  of the PCRF illustrated in  FIG. 6  may be further arranged for determining an already existing group session  172  for the at least one criterion. 
         [0080]    Furthermore, as already commented above, the processing unit  20  is arranged to handle criteria to monitor the user with the group of users, amongst others, those selected from: type of subscription, location area, service usage, corporate users, and combinations thereof. 
         [0081]    Still further, in order to accomplish the above method steps, as illustrated in  FIG. 4  and  FIG. 13A-13B , the output unit  41  of the PCRF  1  shown in  FIG. 6  is arranged for downloading towards the PCEF  2  the policy control rules applicable to said group session, and for indicating corresponding events to be reported. 
         [0082]    In particular, the association between user sessions  161 - 165  and group sessions  171 - 172  in the PCRF  1 , as well as policy control rules for the user session and policy control rules for the group session, may be stored in the storage  10  accessible to the processing unit  20 . Moreover, indications about the events to be reported and other related data may be stored in the storage  10  as well. 
         [0083]    As also commented above, an in order to carry out the above method steps, the present invention provides for a policy enforcement device suitable for acting as, or for replacing, a PCEF of a PCC architecture for installing policy control rules, such as PCC rules, received from a policy decision server  1  in order to handle and control resources in the bearer plane for a plurality of users. 
         [0084]    In this respect,  FIG. 9  illustrates an exemplary implementation of a PCEF  2  implementing the features included in a policy enforcement device in accordance with the third aspect of the invention. 
         [0085]      FIG. 9  thus shows a PCEF  2  including an input unit  57  cooperating with a processing unit  25  for establishing an IP-CAN session  262  for a user  6 ; an output unit  46  for indicating towards a PCRF  1 , as the one illustrated in  FIG. 6 , the establishment of the IP-CAN session for the user  6 ; another input unit  56  arranged for downloading from the PCRF  1  first policy control rules applicable to the user session  262 , namely for the IP-CAN session, and second policy control rules applicable to a given group session  272 , as well as indications of respective events to be reported. 
         [0086]    The processing unit  25  of this PCEF  2  illustrated in  FIG. 9  is also arranged for installing the first and second policy control rules, for associating the IP-CAN session  262  with the group session  272 , and for applying the second policy control rules applicable to the group session  272  to all IP-CAN sessions associated with the group session. 
         [0087]    In particular, the association between IP-CAN sessions and group sessions may be carried out in storage  15  accessible to the processing unit  25 . Moreover, first and second policy control rules, such as PCC rules, may also be stored in the storage  15 . 
         [0088]    Also in particular, the input unit  57  and the input unit  56  may be provided as an integral input unit  55  as illustrated in  FIG. 9  though other arrangements are also possible as the one illustrated in  FIG. 6 . On the other hand, the output unit  46  for communication with the PCRF  1  may be provided as in integral output unit  45  including an output unit  47  for communication with the user equipment in use by the user  6 . Where other arrangements are preferred, such as the one in  FIG. 6 , the present invention may be carried out by providing a first input/output unit, including the output unit  46  and the input unit  56 , for communication between the PCRF and the PCEF, such as the unit  40  shown in  FIG. 6 ; whereas a second input/output unit, including the output unit  47  and the input unit  57 , may be provided at the PCEF for communication between the PCEF and the user equipment in use by the user  6 . 
         [0089]    In order to accomplish method steps in accordance with an embodiment above, namely where the group session is created in the policy enforcement device of the gateway  4 , the input unit  56  may be arranged for receiving a notification from the PCRF  1  indicating at least one criterion to monitor the user  6  along with other users in a group of users, the processing unit  25  may be arranged for assigning a group session for the at least one criterion to monitor the user, and the output unit  46  is arranged for submitting towards the PCRF  1  an identifier of the session group. 
         [0090]    As already commented above, this method is advantageous to take actions at a group level as a response to certain events. In this respect, events to be responded may be any event selected from: events triggered from the policy enforcement device; internal events detected at the policy decision server; and events notified to the policy decision server from an external entity such as a provisioning system, an AF device, or both. 
         [0091]      FIG. 5  illustrates a sequence of actions carried out in this method upon detection of an exemplary first event at the PCEF  2 , which is regarded as a policy enforcement device throughout the present specification. 
         [0092]    As illustrated in  FIG. 5 , upon detection of such event at the PCEF  2 , and assuming this event has been indicated from the PCRF  1  to be reported, the PCEF notifies the occurrence to the PCRF  1  during a step S- 190 . 
         [0093]    The PCRF  1  receiving such notification may determine during a step S- 195  at least one parameter to modify in the currently applicable policy control rules for the group session, and downloads during a step S- 200  the modified policy control rules for the group session towards the PCEF  2 . 
         [0094]    The PCEF  2  installs during a step S- 205  the modified policy control rules for the group session as received from the PCRF  1 , and the PCEF can apply during a step S- 210 , and whilst these policy control rules for the group session are valid and in force, the policy control rules for the group session to all IP-CAN sessions associated with the group session. 
         [0095]    Nevertheless, where the determination carried out during the step S- 195  does not result in any parameter to be modified, the answer carried out during the step S- 200  simply indicates a confirmation of the currently applicable and already installed policy control rules for the group session. 
         [0096]      FIG. 7  illustrates a sequence of actions carried out in this method upon detection of an exemplary second event at the policy enforcement device, namely at the PCEF  2 . 
         [0097]    As illustrated in  FIG. 7 , upon detection of such event at the PCEF  2 , and assuming this second event has also been indicated from the PCRF  1  to be reported, the PCEF notifies the occurrence to the PCRF  1  during a step S- 215 . 
         [0098]    The PCRF  1  receiving such notification may determine during a step S- 220  that a replacement of currently applicable policy control rules for the group session is necessary, generates during a step S- 225  new policy control rules to be replaced at the PCEF for the group session, and downloads during a step S- 230  the new policy control rules to be replaced for the group session towards the PCEF  2 . 
         [0099]    The PCEF  2  installs during a step S- 235  the new policy control rules for the group session as received from the PCRF  1 , and the PCEF can apply, during a step S- 240 , and whilst these new policy control rules for the group session are valid and in force, the new policy control rules for the group session to all IP-CAN sessions associated with the group session. 
         [0100]    As for the above treatment of the exemplary first report illustrated in  FIG. 5 , where the determination carried out during the step S- 220  does not result in a replacement of policy control rules, the answer carried out during the step S- 230  simply indicates a confirmation of the currently applicable and already installed policy control rules for the group session. 
         [0101]      FIG. 8  illustrates a sequence of actions carried out in this method upon detection of an exemplary event at a provisioning system  8 , such as a change of user data. 
         [0102]    As illustrated in  FIG. 8 , upon a change of user data notification received during a step S- 250  at the PCRF  1  from a provisioning system  8 , the PCRF changes the user profile for the given user in accordance with notification data during a step S- 255 . 
         [0103]    Then, the PCRF  1  generates during a step S- 260  new policy control rules applicable to the user session, determines during a step S- 265  a new group which the user is to be monitored with, associates during a step S- 270  the user session for the user with a group session for the new group of users, determines during a step S- 275  those policy control rules applicable for the group session, and downloads during a step S- 280  the new policy control rules applicable for the user and the new control rules applicable for the group session towards the PCEF  2 . 
         [0104]    The PCEF  2  installs during a step S- 285  the new control rules for the user session and the new policy control rules for the group session as received from the PCRF  1 , and the PCEF can apply, during a step S- 290 , and whilst these new policy control rules for the user session and new policy control rules for the group session are valid and in force, the new policy control rules for the group session to all IP-CAN sessions associated with the group session. 
         [0105]    Aligned with the above treatments of the exemplary first and second reports illustrated in  FIG. 5  and  FIG. 7 , where the determination carried out during the step S- 265  does not result in a new group, the new user session is associated with the previously assigned group and there is no need for a replacement of policy control rules. The answer carried out during the step S- 280  downloads the new policy control rules applicable for the user and thus indicates a confirmation of the currently applicable and already installed policy control rules for the group session. 
         [0106]      FIG. 11  illustrates a sequence of actions carried out in this method upon detection of an exemplary event internally at the policy decision server  1 , which as commented above may be acting as, or replacing, a PCRF of a PCC architecture. 
         [0107]    As illustrated in  FIG. 11 , upon detection during a step S- 340  of an internal trigger configured as an event whereby a group session may be modified, such as expiry of a timer, the PCRF  1  may determine during a step S- 345  a necessary replacement of the policy control rules currently applicable for the group session. 
         [0108]    Then, the PCRF  1  may generate during a step S- 350  new policy control rules applicable for the group session, and may download during a step S- 355  said new policy control rules to replace the currently applicable ones for the group session. 
         [0109]    The PCEF  2  installs during a step S- 360  the new policy control rules for the group session as received from the PCRF  1 , and the PCEF can apply, during a step S- 365  and whilst these new policy control rules for the group session are valid and in force, the new policy control rules for the group session to all IP-CAN sessions associated with the group session. 
         [0110]    In a similar manner as for the exemplary first report illustrated in  FIG. 5 , where the determination carried out during the step S- 345  does not result in a replacement of policy control rules, the answer carried out during the step S- 355  simply indicates a confirmation of the currently applicable and already installed policy control rules for the group session. 
         [0111]      FIG. 12  illustrates a sequence of actions carried out in this method upon detection of an exemplary event at an AF device  3  operating in accordance with a PCC architecture for the purpose of the present invention, such as a new service initiated by the user  6 . 
         [0112]    As illustrated in  FIG. 12 , upon notification received during a step S- 370  at the PCRF  1  from the AF  3  of a new service initiated by the user, the PCRF may generate during a step S- 375  policy control rules applicable to the user session. In addition, the PCRF may determine during a step S- 380  at least one criterion to monitor this user along with other users in a group of users, and thus assign during a step S- 385  the user session for the user with a group session for the at least one criterion. In such a case, the PCRF may also determine during a step S- 390  policy control rules applicable to the group session, and may download during a step S- 395  the policy control rules applicable to the user session and the policy control rules for the group session. 
         [0113]    The PCEF  2  installs during a step S- 400  the policy control rules for the user session and the policy control rules for the group session as received from the PCRF  1 , and then the PCEF can apply, during a step S- 405 , and whilst these policy control rules for the group session are valid and in force, the policy control rules for the group session to all IP-CAN sessions associated with the group session. 
         [0114]    Apart from the exemplary events detected at, or reported to, the PCRF  1  and which may lead to either confirm, or modify, or replace the currently applicable policy control rules for the group session towards the PCEF  2 , there may be other events triggering the termination of the group session. 
         [0115]      FIG. 10  illustrates a sequence of actions carried out in this method upon notification during a step S- 300  from the PCEF  2  towards the PCRF  1  of an exemplary event such as the deactivation of the IP-CAN session for the user. 
         [0116]    Upon receipt of such notification, the PCRF  1  may determine during a step S- 305  whether a group session is associated with the user session to be terminated. Then, apart from terminating the user session for the user during a step S- 310 , the PCRF determines during a step S- 315  whether user sessions for other users are still active for said group session and, where no more user sessions for other users are active for said group session, the PCRF may terminate said group session. 
         [0117]    Eventually, the PCRF  1  submits during a step S- 320  an indication to terminate the user session for the user and, where no more user sessions for other users are active for said group session, an indication to also terminate the group session. 
         [0118]    Upon receipt of such indication, the PCEF  2  removes during a step S- 325  the policy control rules for the user session and, where the termination of the group session is also indicated, the PCEF also removes the policy control rules for the group session during this or a further step. 
         [0119]    In order to carry out the above steps of this method for handling the notification of events and for carrying out corresponding actions, the policy decision server acting as, or replacing, a PCRF of a PCC architecture may be further arranged, as illustrated in  FIG. 6 , so that the input unit is arranged for receiving an event selected from a group of events including: events triggered from the policy enforcement device  2 ; internal events detected at the policy decision server  1 ; and events notified to the policy decision server  1  from an external entity selected from a provisioning system  8 , an Application Function device “AF”  3 , and both; and the output unit  41  is arranged for submitting towards the policy enforcement device  2 , responsive to any such event, an indication to either confirm, or modify, or terminate or replace the current policy control rules for the group session. 
         [0120]    Aligned with the behaviour of the policy decision server, and in order to carry out the above steps of this method for handling the notification of events and for carrying out corresponding actions, the policy enforcement device acting as, or replacing, a PCEF of a PCC architecture may be further arranged, as illustrated in  FIG. 9 , so that the output unit  46  is arranged for reporting, upon detection by the processing unit  25 , the respective events. 
         [0121]    Moreover, the input unit  56  of the policy enforcement device  2  may be arranged for receiving an indication from the policy decision server  1  to either confirm, or modify, or terminate, or replace the current second policy control rules applicable for the group session. 
         [0122]    The invention may also be practised by a computer program, loadable into an internal memory of a computer with input and output units as well as with a processing unit. This computer program comprises to this end executable code adapted to carry out the above method steps when running in the computer. In particular, the executable code may be recorded in a carrier readable means in a computer. 
         [0123]    The invention is described above in connection with various embodiments that are intended to be illustrative and non-restrictive. It is expected that those of ordinary skill in this art may modify these embodiments. The scope of the invention is defined by the claims in conjunction with the description and drawings, and all modifications that fall within the scope of the claims are intended to be included therein.