WO2021254645A1

WO2021254645A1 - Layer specific data volume reporting

Info

Publication number: WO2021254645A1
Application number: PCT/EP2020/070811
Authority: WO
Inventors: Raul BARREDA SOTO; Carlos JIMENEZ CORDON; Miguel Angel MUÑOZ DE LA TORRE ALONSO
Original assignee: Telefonaktiebolaget Lm Ericsson (Publ)
Priority date: 2020-06-15
Filing date: 2020-07-23
Publication date: 2021-12-23

Abstract

A method for operating a session management entity (100) configured to manage a data packet session in a cellular network, the method comprising: - receiving from a policy control entity (300), policy rules for the data packet session, the policy rules including a first rule to determine a layer specific amount of data in the data packet session, the layer specific amount of data including the amount of data present only in at least one layer of several layers of a communication model, - transmitting a traffic detection rule for the data packet session to a user plane entity (200) handling the data packet session in the cellular network, the traffic detection rule including a request to detect the amount of data present in only the at least one layer of the several layers, - receiving a session report from the user plane entity (200), the session report including a traffic volume with the amount of data transmitted in the data packet session in the at least one layer of the several layers, - processing the traffic volume transmitted in the at least one layer.

Description

Layer specific data volume reporting

Technical Field

The present application relates to a method for operating a session management entity configured to manage a data packet session in a cellular network. Furthermore, the corresponding session management entity is provided. Additionally, a method for operating a user plane entity handling the data packet session in the network is provided and the corresponding user plane entity. A method for operating a policy control entity is provided and the corresponding policy control entity. Furthermore, a system comprising at least two of the entities mentioned above is provided, a computer program and a carrier comprising the computer program.

Background

Fig. 1 shows a 5G New Radio, NR, architecture with service based interfaces in the Service Based Architecture (SBA). Service Based Interfaces are represented in the format Nxyz, such as Nsmf, and point to point interfaces in the format Nx, such as N4.

The 5G core network part comprises a Network Slice Selection Function (NSSF) 10, a Network Exposure Function (NEF) 15, a Network Repository Function (NRF) 20, a Policy Control Function (PCF) 25, a Unified Data Management (UDM) 30, an Application Function (AF) 35, an Authentication Server Function (AUSF) 40, an Access and Mobility Management Function (AMF) 45, and a Session Management Function (SMF) 50. Having service based interfaces in the 5G Core Control Plane (CP), implies that the Network Functions (NFs) in the 5G Core CP provide services that are consumed by other NFs in the 5G Core CP.

A User Equipment (UE) 60, is connected to the Radio Access Network (RAN) 65, wherein a User Plane Function (UPF) 70 is provided to connect the UE 60 to a Data Network (DN) 75. SBA: In 5G core network architecture, the ‘network elements’ is made available through Application Programming Interfaces (APIs). These ‘network elements’, are defined as Network Functions (NFs), and the architecture where each NF offers one or more service to other NFs is called Service-Based Architecture, SBA. Fig. 2 shows the 5G 5GC architecture for policy charging and analytics. In addition to the nodes or functions shown in Fig. 1, the Unified Data Repository (UDR), 80 and the Network Data Analytics Function (NWDAF) 85, and the Charging Function 90 are provided.

In the following, some of the functions/nodes are explained in more detail.

The Charging Function (CHF) 90 supports offline and online charging functionality and exposes the Nchf interface towards the consumers (e.g. SMF).

The Policy Control Function (PCF) 25 supports unified policy framework to govern the network behaviour. Specifically, PCF provides PCC (Policy and Charging Control) rules to the SMF 50. The Session Management function (SMF) 50 supports different functionality, e.g. Session Establishment, modify and release, and policy related functionalities like termination of interfaces towards Policy control functions, Charging data collection, support of charging interfaces and control and coordination of charging data collection at UPF. Specifically, SMF 50 receives PCC rules from PCF 25 and configures UPF 70 accordingly through N4 reference point (PFCP protocol) as follows:

• SMF 50 controls the packet processing in the UPF 70 by establishing, modifying or deleting PFCP Sessions and by provisioning (i.e. adding, modifying or deleting) PDRs, FARs, QERs and/or URRs per PFCP session, whereby a PFCP session may correspond to an individual PDU session or a standalone PFCP session not tied to any PDU session.

• Each PDR contains a PDI specifying the traffic filters or signatures against which incoming packets are matched. Each PDR is associated to the following rules providing the set of instructions to apply to packets matching the PDI: one FAR, which contains instructions related to the processing of the packets, specifically forward, duplicate, drop or buffer the packet with or without notifying the CP function about the arrival of a DL packet. zero, one or more QERs, which contains instructions related to the QoS enforcement of the traffic; zero, one or more URRs, which contains instructions related to traffic measurement and reporting.

UPF (User Plane Function) The User Plane function (UPF) supports handling of user plane traffic based on the rules received from SMF, specifically, for this IvD, packet inspection (through PDRs) and different enforcement actions, e.g. traffic steering, QoS, Charging/Reporting (through FARs, QERs, URRs).

The 3GPP TS 29.244 specifies the PFCP protocol, specifically traffic analysis and classification through PDRs and reporting through URRs but this has the following problems: The current mechanism for volume reporting does not allow any flexibility in terms of the granularity of traffic to be reported. Furthermore, network operators require detailed reports, and they have different requirements on the base information used to charge, e.g. for IPv4 or IPv6 traffic, some network operators charge for the total number of bytes (including the L3 and L4 headers) while others only charge for the application payload (L7).

Summary

Accordingly, a need exists to overcome the above-mentioned drawbacks and to provide the possibility to have a more granular information about the amount of exchanged data.

This need is met by the features of the independent claims. Further aspects are described by the dependent claims.

According to a first aspect, a method for operating a session management entity is provided, which is configured to manage a data packet session in a cellular network. The method comprises the step of receiving policy rules for the data packet session from a policy control entity, wherein the policy rules include a first rule to determine a layer specific amount of data in the data packet session, wherein the layer specific amount of data includes the amount of data present only in at least one layer of several layers of a communication model. Furthermore, a traffic detection rule is transmitted for the data packet session to a user plane entity handling the data packet session in the cellular network, wherein the traffic detection rule includes a request to detect the amount of data present in only the at least one layer of the several layers. Furthermore, a session report is received from the data plane entity, wherein the session report includes a traffic volume with the amount of data transmitted in the data packet session in the at least one layer of the several layers. This traffic volume transmitted in the at least one layer is then further processed.

Furthermore, the corresponding session management entity is provided comprising a memory and at least one processing unit, wherein the memory contains instructions executable by the at least one processing unit. The session management entity is operative to work as discussed above or as discussed in further detail below.

Alternatively, a session management entity is provided configured to manage the data packet session, the session management entity comprising a first module configured to receive the policy rules from the policy control entity, wherein the policy rules include the rule to detect a layer specific amount of data in a data packet session, wherein the layer specific amount includes the amount of data present in only at least one of the layers. A second module of the session management entity is configured to transmit the traffic detection rule for the data packet session to the user plane entity handling the data packet session in the cellular network. This traffic detection rule then includes the request to detect the amount of data present in only the at least one layer. A third module of the session management entity is configured to receive the session report from the data plane entity which includes the traffic volume with the amount of data transmitted in the data packet session in the at least one layer of the several layers. A further module, a fourth module of the session management entity is configured to process the traffic volume transmitted in the at least one layer.

Accordingly, with this method for operating the session management entity and with this session management entity, a layer specific volume reporting can be enabled or disabled. This session management entity can activate a layer specific reporting by informing the user plane entity to carry out a layer specific counting of the transmitted data. Furthermore, the request to the user plane entity or the detection rule specifies for which of the layers the amount of data is needed.

Furthermore, a method for operating the user plane entity is provided which is configured to handle the data packet session in the cellular network. The user plan entity receives the traffic detection rule for the data packet session, wherein this rule includes the request to detect the layer specific amount of data including the amount of data present only in at least one layer of the several layers transmitted in the data packet session. Furthermore, the data packets of the data packet session are classified in order to identify the data packets belonging to the at least one layer specified in the traffic detection rule. Furthermore, a traffic volume is determined with the amount of the data packets belonging to the at least one layer and a session report is transmitted to the session control entity which includes the traffic volume with the amount of data transmitted in the data packet session and the at least one layer.

Furthermore, the corresponding user plane entity is provided comprising a memory and at least one processing unit, wherein the memory contains instructions executable by the at least one processing unit, wherein the user plane entity is operative to work as discussed above or as discussed in further detail below.

Alternatively, a user plane entity is provided configured to handle a data packet session in the cellular network which comprises a first module configured to receive the traffic detection rule for the data packet session, wherein this traffic detection rule includes the request to detect a layer specific amount of data including the amount of data present only in at least one layer of several layers transmitted in the data packet session. As further module is configured to classify the data packets of the data packet session in order to identify the data packets belonging to the at least one layer specified the traffic detection rule. A further module is configured to determine a traffic volume with an amount of data packets belonging to the at least one layer and a further module is configured to transmit a session report to a session control entity of the cellular network including the traffic volume with the amount of data transmitted in the data packet session and at least one layer.

Furthermore, a method for operating a policy control entity is provided, wherein the policy control entity receives from a subscriber database a policy for the data packet session of the subscriber of the cellular network, wherein the policy comprises an indication that a layer specific amount of data in the data packet session is to be determined, wherein the layer specific amount of data includes the amount of data present only in at least one of the several layers of a communication model. Furthermore, policy rules are transmitted for the data packet session the session management entity, wherein the policy rules include a first rule to determine the layer specific amount of data in the data packet session and wherein this layer specific amount of data includes the amount of data present only in at least one of several layers.

Furthermore, the corresponding policy control entity is provided comprising a memory and at least one processing unit, wherein the memory contains instructions executable by the at least one processing unit, wherein the policy control entity is operative to work as discussed above or as discussed in further detail below.

As an alternative, a policy control entity is provided comprising a first module configured to receive from a subscriber database of the cellular network a policy for a data packet session for subscriber, wherein the policy comprises the indication that a layer specific amount of data is to be determined in the data packet session and the layer specific amount includes the amount of data present in only one of the several layers of a communication model. A second module is configured to transmit policy rules for the data packet session to a session management entity, and the policy rules include a first rule to determine a layer specific amount of data for the data packet session, wherein the layer specific amount of data includes the amount of data present only in the at least one of the several layers.

Additionally, a system is provided comprising at least two of the entities mentioned above.

Furthermore, a computer program comprising program code is provided, wherein execution of the program code causes the at least one processing unit of the session management entity, the user plane entity or the policy control entity to execute a method as discussed above or as discussed in further detail below. Furthermore, a carrier comprising the computer program is provided, wherein the carrier is one of an electronic signal, optical signal, radio signal, or computer readable storage medium.

It is to be understood that the features mentioned above and features yet to be explained below can be used not only in the respective combinations indicated, but also in other combinations or in isolation without departing from the scope of the present invention. Features of the above- mentioned aspects and embodiments described below may be combined with each other unless explicitly mentioned otherwise.

Brief Description of Drawings

The foregoing and additional features and effects of the application will become apparent from the following detailed description when read in conjunction with the accompanying drawings in which like reference numerals refer to like elements.

Fig. 1 shows a schematic view of a network architecture used in a 5G network as known in the art.

Fig. 2 shows a schematic view of the network architecture used for policy, charging and analytics in a 5G network as known in the art.

Fig. 3 shows a schematic view of a table of the features of the user plane entity extended with the information that the user plane entity supports the layer specific volume reporting.

Fig. 4 shows a schematic view of an implementation of a usage reporting rule used for the layer specific volume reporting. Fig. 5 shows a schematic view of a report by a user plane entity in response to the reporting rule for the layer specific volume.

Fig. 6 shows a schematic view of a possible implementation of a volume measurement.

Fig. 7 shows a schematic view of a first part of a message flow including the exchanged messages between the entities involved for a layer specific volume reporting.

Fig. 8 shows a schematic view of the continued message flow shown in Fig. 7.

Fig. 9 shows an example flowchart of a method carried out by the session management entity in order to initiate a layer specific volume reporting.

Fig. 10 shows an example flowchart of a method carried out by a user plane entity which counts a layer specific volume and informs other entities of the layer specific volume.

Fig. 11 shows an example flowchart of a method carried out by a policy control entity in the layer specific volume reporting.

Fig. 12 shows an example schematic representation of a session management entity configured to initiate a layer specific volume reporting.

Fig. 13 shows another example schematic representation of a session management entity configured to initiate the layer specific volume reporting.

Fig. 14 shows an example schematic representation of a user plane entity configured to handle the data packet session and to carry out the layer specific volume counting.

Fig. 15 shows another example schematic representation of a user plane entity configured to handle the data packet session and to carry out the layer specific volume reporting.

Fig. 16 shows an example schematic representation of a policy control entity configured to provide the policies required for the layer specific volume reporting.

Fig. 17 shows another example schematic representation of a policy control entity configured to provide the policies required for the layer specific volume reporting. Detailed Description of Drawings

In the following, embodiments of the invention will be described in detail with reference to the accompanying drawings. It is to be understood that the following description of embodiments is not to be taken in a limiting sense. The scope of the invention is not intended to be limited by the embodiments described hereinafter, or by the drawings which are to be illustrative only.

The drawings are to be regarded as being schematic representations, and elements illustrated in the drawings are not necessarily shown to scale. Rather, the various elements are represented such that their function and general purpose becomes apparent to a person skilled in the art. Any connection or coupling between functional blocks, devices, components of physical or functional units shown in the drawings and described hereinafter may also be implemented by an indirect connection or coupling. A coupling between components may be established over a wired or wireless connection. Functional blocks may be implemented in hardware, software, firmware, or a combination thereof.

Within the context of the present application, the term “mobile entity” or “user equipment” (UE) refers to a device for instance used by a person (i.e. a user) for his or her personal communication. It can be a telephone type of device, for example a telephone or a Session Initiating Protocol (SIP) or Voice over IP (VoIP) phone, cellular telephone, a mobile station, cordless phone, or a personal digital assistant type of device like laptop, notebook, notepad, tablet equipped with a wireless data connection. The UE may also be associated with non humans like animals, plants, or machines. A UE may be equipped with a SIM (Subscriber Identity Module) or electronic-SIM comprising unique identities such as IMSI (International Mobile Subscriber Identity), TMSI (Temporary Mobile Subscriber Identity), or GUTI (Globally Unique Temporary UE Identity) associated with the user using the UE. The presence of a SIM within a UE customizes the UE uniquely with a subscription of the user.

For the sake of clarity, it is noted that there is a difference but also a tight connection between a user and a subscriber. A user gets access to a network by acquiring a subscription to the network and by that becomes a subscriber within the network. The network then recognizes the subscriber (e.g. by IMSI, TMSI or GUTI or the like) and uses the associated subscription to identify related subscriber data. A user is the actual user of the UE, and the user may also be the one owning the subscription, but the user and the owner of the subscription may also be different. E.g. the subscription owner may be the parent, and the actual user of the UE could be a child of that parent. In the following, a solution is disclosed which allows a layer specific volume reporting. As known in any communication system, the communication can be modelled by different layers, wherein the most common model is the Open Systems Interconnection model, or OSI model. In this model or any other communication model, the different functions of the communication are implemented in different layers such as the physical layer, layer 1 , a network layer known as layer 3 of the OSI model, a transport layer, known as layer 4 or the application layer known as layer 7 in the OSI model. However, the application is not restricted to the OSI model, other models may be used. Accordingly, the layer specific amount of data transmitted in a data packet session is calculated.

In the following, when reference is made to the different nodes implemented in the cellular network, the nodes may be specified as entities such as user plane entity or session management entity. In this context, the expression "entity" may also be understood as a function so that the terms user plane entity or user plane function can be used interchangeably.

In the cellular network, a new feature such as the layer specific reporting can be enabled or disabled, by way of example for a network layer, a transport layer and/or an application layer volume reporting. This reporting can be on a per subscriber or on a per group of subscriber basis or on a per node basis. Furthermore, the feature can be enabled for a particular application or for any policy and control and charging rule, PCC.

In the following, an implementation will be discussed in more detail which is based on the packet forwarding control protocol, PFCP, which is used in an interface between the control plane entity with a user plane for a 5G network. However, the same features could be implemented in another cellular network such as a 4G network or any other cellular network and other protocols may be used in this context.

In an association procedure used by the protocol, such as the PFCP association, a user plane entity reports to the session management entity a new capability, namely that it is able to handle a layer specific volume reporting also mentioned as extended volume level reporting hereinafter. This allows the session management entity to select a user plane entity supporting this capability on a per session basis.

For each data packet session, such as each PFCP session, the session management entity activates the layers specific volume reporting in the user plane entity, by way of example by provisioning traffic detection rules such as a usage reporting rule, URR, which is extended to specifically request the layer specific reporting such as a network layer reporting, a transport layer reporting and/or the application layer reporting. Furthermore, different granularity levels are possible.

One possible implementation is based on a per session basis so that for the complete traffic of the session the layer specific data volume is determined. Furthermore, it is possible to use a more granular basis, in which only traffic matching a certain application such as Netflix or YouTube is addressed. This can be enabled by a policy control unit both on a per subscriber and on a per PCC rule basis. In the example above, the PCC rule corresponds to the Netflix or YouTube application.

The user plane entity analyses the traffic for the data packet session and for the traffic matching the traffic detection rule associated to the URR and extended to the layer specific volume reporting, it measures the corresponding layer specific volume for the layer indicated in the traffic detection rule. The traffic detection rule can be implemented as packet detection rule, PDR. When the user plane entity provides the report to the session management entity, the corresponding report may be extended to report the corresponding layer specific volume. By way of example, the usage reporting rule may be extended to report the corresponding layer specific volume. The user plane entity is asked to differentiate the data volume of the data packet session on a per layer basis and to determine the data volume for the layer or layers indicated in the traffic detection rule.

The session management entity receives this session report or usage reporting rule report from the user plane entity and processes the received information such as reporting the corresponding layer specific volume for reporting and/or charging purposes, by way of example by forwarding this information to the charging function.

In connection with Fig. 3 - Fig. 8, one possible implementation is discussed which is based on extending the PFCP protocol, especially the URR for the network, transport and/or application layer volume reporting. In the example shown in the figures, the application level volume reporting is enabled on a per PDU session basis.

In the example given below, the application level volume reporting policy is provided in the UDR as subscriber policy data.

Reference is made to Fig. 7 and 8. In steps S11 and S12, at the association procedure between the UPF entity SMF, at the PFCP association, the reporting mechanism is extended to report the capabilities of the user plane entity with the new capability of the extended volume level reporting corresponding to the layer specific reporting feature. This is also shown in Fig. 3 in the last line of the table in bold letters. This allows the session management entity to know which of the user plane entities support this capability and so that this capability can be considered when selecting a user plane entity for a data packet session. In the implementation shown in this PFCP association request including the UPF capabilities with the extended volume level reporting. The response in step S12 is the PFCP association response. For the PFCP implementation the steps could be implemented as follows - S11 : PFCP association request, UPF capabilities: extended volume level reporting, S12: PFCP association response.

In step S13, the UE transmits a request for a data packet session to the AMF (Access and Mobility Management Function) (S13: PDU session establishment request). This step can be implemented as a PDU session establishment request. The AMF then selects an SMF to manage the PDU session, the SMF selection function in the AMF selects an SMF instance based on the available SMF instances obtained from NRF or on the configured SMF information in the AMF and transmits a session create message to the SMF. Accordingly, in step S14: Nsmf PDU session create, the message can be implemented as an Nsmf PDU session create message. It should be noted that the sequence diagram of Fig. 7 and 8 does not include all the signalling messages involved in the PDU session establishment procedure.

The relevant signalling messages are described in subsequent steps.

In step S15, SMF triggers Npcf_SMPolicyControl_Create request message to retrieve SM policies for the user PDU session (S15: Npcf_SMPolicyControl_Create request).

In step S16, PCF triggers Nudr_Query request message including the subscriber identifier to retrieve the policy data for this subscriber^'s PDU session (S16: Nudr_Query request (subscriber identifier) ) .

In step S17, UDR answers with Nudr_Query response message including the Subscriber Policy Data or profile, which includes an application level volume reporting policy (S17: Nudr_Query response (subscriber profile including application level volume reporting)). In the example of the sequence diagram in Fig. 7, the solution proposed is enabled on a per subscriber basis (specifically for this subscriber^'s PDU session), but it can also be enabled on a per PCC rule basis (e.g. for the PCC rule corresponding to the Netflix application, and not for the other PCC rules).

In step S18, PCF generates the corresponding PCC rule/s based on Subscriber Policy Data, including an extension to indicate (e.g. with a flag) to enable application level volume reporting (for all the PCC rules in this example) (S18: Npcf policy response (PCC rules including application level volume reporting)). It is also proposed to allow enabling volume reporting at different levels simultaneously (e.g. both on a per network and on a per application basis).

In steps S19 and S20, SMF triggers PFCP Session Establishment procedure towards UPF to provision the PDRs (and the corresponding enforcement actions: FARs, URRs, etc.) for the PDU session (S19: PFCP session establishment request (PDRs, URRs (requesting application level volume reporting)), S20: PFCP session establishment response). Specifically, SMF will provision in the URRs an indication to enable application level volume reporting. In order to do this, it is proposed extend the PFCP protocol by adding a new flag (bit) in Measurement Information IE at “PFCP Session Establishment/Modification Request” in “Create/Update URR IE”, as shown in Fig. 4 in bold.

Fig. 4 show a possible implementation of the Information Element (IE), and a usage reporting rule (URR) within a request for a session establishment, implemented in the PFCP protocol.

In general, as a PDR might be associated to several URRs, SMF only needs to add the new application level volume measurement flag (in Measurement Information IE) for the URRs that need to report the application level volume.

In Fig. 8 in step S21 , after the PDU session is established, UE sends application traffic (e.g. a TCP SYN message) towards the application server (S21: application traffic).

In step S22, UPF classifies this traffic in the corresponding PDR, which is associated to a URR requesting application level volume reporting, so UPF measures and stores the application volume (L7 payload). In step S23, the application traffic is forwarded to the application server.

In steps S24 - S26, when the URR threshold (e.g. periodic or volume threshold) is reached, UPF triggers a URR report including the application level volume (L7 payload), if the URR includes the new application level volume measurement flag in step S19 above (S25: PFCP session report request (URR including application level volume), S26: PFCP session report response). This volume is proposed to be included in the Volume Measurement IE (see table in Fig. 5 in bold) in the Usage Report IE within PFCP Session Report Request message.

As mentioned, it is also proposed to allow enabling volume reporting at different levels simultaneously (e.g. both on a per network and on a per application basis). In this case, it is proposed to extend the existing Volume Measurement IE by using the spare bits (in Octet 5) to indicate the granularity level (network, transport or application) as shown in bold in Fig. 6.

In steps S27 - S29, SMF triggers online/offline charging including application level volume. Specifically, SMF triggers a Nchf charging request including the application level volume (L7 payload) (S28: Nchf charging request (charging information including application level volume), S29: Nchf charging response).

In step S30, CHF applies the corresponding logic, e.g. to reflect the application level volume (L7 payload) in the charging record for the subscriber.

Fig. 9 summarizes some of the steps carried out by the SMF or session management entity in the message flow indicated above. In step S111, the session management entity receives policy rules, wherein these policy rules include a rule to determine a layer specific amount of data in the data packet session. This layer specific amount of data to be determined includes only the data indicated in one or several of the layers, but not of the other layers not indicated in the rule. The session management entity then transmits in step S112 a traffic detection rule to the UPF handling the data packet session. This traffic detection rule includes the request to detect the layer specific traffic as indicated above in step S19 in Fig. 7. Furthermore, the session management entity receives a session report from the UPF including the traffic volume in the required layer or layers as mentioned above in step S25. Furthermore, this traffic volume as received in the session report is processed further, by way of example a charging message is generated and transmitted to the charging function as shown by step S28 above.

Fig. 10 shows some of the steps carried out by the user plane entity in the above discussed message exchange. In step S121 , the user plane entity receives the traffic detection rule which has been transmitted by the SMF as discussed above in step S112 and as mentioned in step S19 of Fig. 7. When the user plane entity is handling the data packets of the data packet session, the data packets are classified in order to identify the data packets belonging to the layer as specified in the received traffic detection rule. The traffic detection rule can indicate to detect the traffic of one specific layer, of two specific layers or of three specific layers or of more layers. Furthermore, the detection rule can indicate that the traffic is to be detected on a subscriber basis or on a per session basis relating only to data packets of a certain application. In step S122, the data packets are classified based on the layer as shown by step S22 above. In step S123, the layer specific traffic volume is determined as specified in step S24 above and, in step S124, a session report is transmitted to the SMF as mentioned above in step S25.

Fig. 11 summarizes some of the steps carried out by the policy control entity in the message exchange shown above. In step S131, the policy control entity receives from the subscriber database a policy for the data packet session, which includes indication that a layer specific amount of data should be determined. As mentioned in step S17, the policy data include the information for which of the layers the layer specific amount of data should be determined. In step S132, the policy rules are transmitted to the session management entity as indicated in step S18 above. The policy rules include the rule, also named first rule, to determine a layer specific amount of data for the layers indicated in the rule.

Fig. 12 shows a schematic architectural view of the session management entity 100, which can operate as discussed above in which can especially instruct the user plane entity to detect the layer specific traffic. The session management entity 100 comprises an interface 110, which is provided for transmitting user data and/or control messages to other entities and is configured to receive user data and/or control messages from other entities. The interface is especially qualified to receive the policy rules with the request to determine the layer specific amount of data and is especially configured to transmit the traffic detection rule to the user plane entity and to receive the session report from the user plane entity. The session management entity furthermore comprises a processing unit 120, which is responsible for the operation of the session management entity 100. The processing entity 120 comprises one or more processors and can carry out instructions stored on a memory 130, wherein the memory may include a read-only memory, a random access memory, a mass storage, a hard disk or the like. The memory can furthermore include suitable program code to be executed by the processing unit 120 so as to implement the above-described functionalities in which the session management entity is involved.

Fig. 13 shows another schematic architectural view of a session management entity, which comprises a first module 410 configured to receive the policy rules from the policy control entity which include the rule to determine a layer specific amount of data for a data packet session. A second module 420 is configured to transmit a traffic detection rule to the user plane entity, wherein this traffic detection rule includes the request to detect the amount of data present in only the at least one layer as received in the policy rules from the policy control entity. The session management entity 400 comprises a third module configured to receive the session report from the user plane entity which includes the requested layer specific volume. A fourth module 440 is configured to process the traffic volume.

Fig. 14 shows a schematic architectural view of a user plane entity 200. The user plane entity 200 comprises an interface 210 which is provided for transmitting the user data or control messages to other entities. By way of example, the data packets of the data packet session are received and forwarded. Furthermore, control messages are received, by way of example from the session management entity or the UE. The interface is especially configured to receive the traffic detection rule with the request to detect a certain layer specific amount of data for one or several layers in the data packet session. The interface is furthermore configured to transmit a session report to the session control entity including the amount of data transmitted in the data packet session in the layer as requested. The user plane entity 200 furthermore comprises a processing unit 220, which is responsible for the operation of the user plane entity 200. The processing unit 220 can comprise one or more processors and can carry out instructions stored on a memory 230, wherein the memory may include a read-only memory, a random access memory, a mass storage, a hard disk, or the like. The memory 230 can furthermore include suitable program code to be executed by the processing unit 220 so as to implement the above described functionalities in which the user plane entity is involved.

Fig. 15 shows a further schematic architectural view of a user plane entity 500 comprising a first module 510 configured to receive the policy rules including the request to detect a layer specific amount of data for one or several layers. A second module 520 of the user plane entity 500 is configured to classify the data packets of the data packet session in order to identify the data packets belonging to the at least one layer which was specified in the traffic detection rule. A third module 530 is configured to determine traffic volume with the amount of data packets belonging to the layer as identified in the traffic detection rule and a fourth module 540 is configured to transmit a session report to the session control entity including the traffic volume.

Fig. 16 shows a schematic architectural view of a policy control entity 300, which comprises an interface 310 configured to transmit user data or control messages to other entities and configured to receive user data and control messages from other entities. The interface is especially configured to receive the policy from the subscriber database including the information or indication that a layer specific amount of data should be determined. The interface 310 is furthermore configured to transmit the policy rules to the session management entity including the rule to determine the layer specific amount of data. The policy control entity furthermore comprises a processing unit 320, which is responsible for the operation of the policy control entity. The processing unit 320 comprises one or more processors and can carry out instructions stored on a memory 330, wherein the memory may include a read-only memory, a random access memory, a mass storage, a hard disk, or the like. The memory 330 can furthermore include suitable program code to be executed by the processing unit 320 so as to implement the above described functionalities in which the policy control entity 300 is involved.

Fig. 19 shows another schematic architectural view of the policy control entity 600 comprising a first module 610 configured to receive the policy for the data packet session from the subscriber database, wherein the policy comprises the request to determine a layer specific amount of data. A second module 620 is configured to transmit the policy rules to the session management entity, wherein this policy rules include the rule to determine a layer specific amount of data for the layers as indicated from the subscriber database.

From the above said some general conclusions can be drawn for the different entities involved. (Here we summarize the dependent claims.)

As far as the session management entity or SMF is concerned, when the SMF processes the received session report including the traffic volume, the processing can mean that a charging message is generated which includes the amount of data present in only the at least one layer, wherein this charging message is transmitted to a charging entity of the cellular network.

The traffic detection rule which the session management entity transmits to the user plane entity can indicate that only the amount of data transmitted in the at least one layer is to be detected and not the amount of data transmitted in any of the other layers of the several layers not including the at least one layer. Accordingly, this means that the traffic detection rule specifies in detail for which of the layers or for which combination of layers the data packet volume should be determined.

Furthermore, the traffic detection rule may include the request to detect the amount of data transmitted only in a single layer of the several layers, wherein this single layer can be a transport layer, a network layer or an application layer.

Furthermore, it is possible that the traffic detection rule includes the request to detect the amount of data transmitted to only two layers of the several layers, wherein the two layers are selected from a group comprising the transport layer, the network layer, and the application layer. The session management entity can furthermore receive an indication from the user plane entity that the user plane entity has the capability to detect a layer specific amount of data in which only data present in the at least one layer is detected. This was discussed above in connection with step S11 in which the user plane entity informs the session management entity upfront in the association process that it has the capability to detect a layer specific amount of data.

The session report as received from the user plane entity can be received as part of a usage reporting rule transmitted by the user plane entity.

As far as the user plane entity is concerned, the session report which is transmitted to the session control entity may be transmitted when a defined event is detected. This defined event can mean that a certain volume threshold is detected in the counted data or that a defined time period has lapsed.

The packet detection rule may include the request to detect the layer specific amount of data only for data packets of the data packet session related to a defined application provided by a service providing entity. As indicated above, this can mean that only traffic from a certain service provider such as Netflix etc. should be considered in this context. The layer specific amount of traffic is especially determined for the requested application and the session report includes the layer specific amount of data for this application.

Furthermore, the packet detection rule may include the request to detect the layer specific amount of data only for data packets of the data packet session related to a defined subscriber or to a group of subscribers, which are subscribers to the cellular network. Here the traffic volume is determined for the defined subscriber or the defined group of subscribers and the session report transmitted includes the information for the identified subscriber or group of subscribers.

The solution discussed above does not only apply to a 5G network, but the same mechanism may also be applied to an LTE or 4G network, in which the PCF is replaced by the PCRF and the SMF is replaced by the packet gateway controller or traffic detection function control entity, wherein the UPF is replaced by the user plane gateway or the TDF-U. The above discussed solution has the advantage that it is possible to differentiate between the different layers of the data traffic occurring in the cellular network. This can be used for reporting and for charging purposes.

Claims

1. A method for operating a session management entity (100) configured to manage a data packet session in a cellular network, the method comprising:

- receiving from a policy control entity (300), policy rules for the data packet session , the policy rules including a first rule to determine a layer specific amount of data in the data packet session, the layer specific amount of data including the amount of data present only in at least one layer of several layers of a communication model,

- transmitting a traffic detection rule for the data packet session to a user plane entity (200) handling the data packet session in the cellular network, the traffic detection rule including a request to detect the amount of data present in only the at least one layer of the several layers,

- receiving a session report from the user plane entity (200), the session report including a traffic volume with the amount of data transmitted in the data packet session in the at least one layer of the several layers,

- processing the traffic volume transmitted in the at least one layer.

2. The method according to claim 1, wherein the processing comprises generating a charging message including the amount of data present in only the at least one layer and transmitting the charging message to the policy control entity in charging entity of the cellular network.

3. The method according to claim 1 or 2, wherein the traffic detection rule indicates that only the amount of data transmitted in the at least one layer is to be detected and not the amount of data transmitted in any other layer of the several layers not including the at least one layer.

4. The method according to any of the preceding claims, wherein the traffic detection rule includes the request to detect the amount of data transmitted only in a single layer of the several layers, the single layer including one a transport layer, a network layer, and an application layer.

5. The method according to any of claims 1 to 3, wherein the traffic detection rule includes the request to detect the amount of data transmitted only in two layers of the several layers, the two layers being selected from a group including a transport layer, a network layer, and an application layer.

6. The method according to any of the preceding claims, further receiving an indication from the user plane entity (200) that the user plane entity has a capability to detect a layer specific amount of data in which only data present in at least one layer of the several layers is detected.

7. The method according to any of the preceding claims, wherein the session report is received as part of a Usage Reporting Rule.

8. A method for operating a user plane entity (200) configured to handle a data packet session in a cellular network, the method comprising:

- receiving a traffic detection rule for the data packet session, the traffic detection rule including the request to detect a layer specific amount of data including the amount of data present only in at least one layer of several layers transmitted in the data packet session,

- classifying the data packets of the data packet session in order to identify the data packets belonging to the at least one layer specified in the traffic detection rule,

- determining a traffic volume with an amount of the data packets belonging to the at least one layer,

- transmitting a session report to a session control entity (100) of the cellular network including the traffic volume with the amount of data transmitted in the data packet session in the at least one layer.

9. The method according to claim 8, wherein the session report is transmitted when a defined event is detected.

10. The method according to claim 9, wherein the defined event comprises a detection of a volume threshold.

11. The method according to claim 9, wherein the defined event comprises a detection that a defined time period has lapsed.

12. The method according to any of the preceding claims, wherein the packet detection rule includes the request to detect the layer specific amount of data only for data packets of the data packet session related to a defined application provided by a service providing entity, wherein the session report includes the layer specific amount of data only related to the defined application.

13. The method according to any of the preceding claims, wherein the packet detection rule includes the request to detect the layer specific amount of data only for data packets of the data packet session related to a defined subscriber or to a group of subscribers to the cellular network, wherein the session report includes the layer specific amount of data only related to the defined subscriber or group of subscribers.

14. A method for operating a policy control entity (300) in a cellular network, the method comprising:

- receiving, from a subscriber database, a policy for a data packet session of a subscriber of the cellular network, the policy comprising an indication that a layer specific amount of data in the data packet session is to be determined, the layer specific amount of data including the amount of data present only in at least one of several layers of a communication model,

- transmitting policy rules for the data packet session to a session management entity, the policy rules including a first rule to determine the layer specific amount of data in the data packet session, the layer specific amount of data including the amount of data present only in the at least one of several layers.

15. A session management entity configured to manage a data packet session in a cellular network, the session management entity comprising a memory and at least one processing unit, the memory containing instructions executable by the at least one processing unit, wherein the session management entity is operative to:

- receive from a policy control entity (300), policy rules for the data packet session, the policy rules including a first rule to determine a layer specific amount of data in the data packet session, the layer specific amount of data including the amount of data present only in at least one layer of several layers of a communication model,

- transmit a traffic detection rule for the data packet session to a user plane entity (200) handling the data packet session in the cellular network, the traffic detection rule including a request to detect the amount of data present in only the at least one layer of the several layers,

- receive a session report from the data plane entity(200), the session report including a traffic volume with the amount of data transmitted in the data packet session in the at least one layer of the several layers,

- process the traffic volume transmitted in the at least one layer.

16. The session management entity according to claim 15, further being operative, for processing the traffic volume, to generate a charging message including the amount of data present in only the at least one layer and to transmit the charging message to the policy control entity.

17. The session management entity according to claim 15 or 16, wherein the traffic detection rule indicates that only the amount of data transmitted in the at least one layer is to be detected and not the amount of data transmitted in any other layer of the several layers not including the at least one layer.

18. The session management entity according to any of claims 15 to 17, wherein the traffic detection rule includes the request to detect the amount of data transmitted only in a single layer of the several layers, the single layer including one a transport layer, a network layer, and an application layer.

19. The session management entity according to any of claims 15 to 17, wherein the traffic detection rule includes the request to detect the amount of data transmitted only in two layers of the several layers, the two layers being selected from a group including a transport layer, a network layer, and an application layer.

20. The session management entity according to any of claims 15 to 19, further being operative to receive an indication from the user plane entity (200) that the user plane entity has a capability to detect a layer specific amount of data in which only data present in at least one layer of the several layers is detected.

21. The session management entity according to any of claims 15 to 19, further being operative to receive the session report as part of a Usage Reporting Rule.

22. A user plane entity (200) configured to handle a data packet session in a cellular network, the user plane entity comprising a memory and at least one processing unit, the memory containing instructions executable by the at least one processing unit, wherein the user plane entity is operative to:

- receive a traffic detection rule for the data packet session, the traffic detection rule including the request to detect a layer specific amount of data including the amount of data present only in at least one layer of several layers transmitted in the data packet session,

- classify the data packets of the data packet session in order to identify the data packets belonging to the at least one layer specified in the traffic detection rule,

- determine a traffic volume with an amount of the data packets belonging to the at least one layer,

- transmit a session report to a session control entity (100) of the cellular network including the traffic volume with the amount of data transmitted in the data packet session in the at least one layer.

23. The user plane entity according to claim 22, further being operative to transmit the session report when a defined event is detected.

24. The user plane entity according to claim 23, wherein the defined event comprises a detection of a volume threshold or a detection that a defined time period for has lapsed.

25. The user plane entity according to any of claims 22 to 24, wherein the packet detection rule includes the request to detect the layer specific amount of data only for data packets of the data packet session related to a defined application provided by a service providing entity, wherein the session report includes the layer specific amount of data only related to the defined application.

26. The user plane entity according to any of claims 22 to 25, wherein the packet detection rule includes the request to detect the layer specific amount of data only for data packets of the data packet session related to a defined subscriber or to a group of subscribers to the cellular network, wherein the session report includes the layer specific amount of data only related to the defined subscriber or group of subscribers.

27. A policy control entity (300) provided in a cellular network, the policy control entity comprising a memory and at least one processing unit, the memory containing instructions executable by the at least one processing unit, wherein the policy control entity is operative to:

- receive, from a subscriber database, a policy for a data packet session of a subscriber of the cellular network, the policy comprising an indication that a layer specific amount of data in the data packet session is to be determined, the layer specific amount of data including the amount of data present only in at least one of several layers of a communication model,

- transmit policy rules for the data packet session to a session management entity, the policy rules including a first rule to determine the layer specific amount of data in the data packet session, the layer specific amount of data including the amount of data present only in at least one of several layers of a communication model.

28. A system comprising at least two entities selected from the following group of entities: a session management entity as mentioned in any of claims 15 to 21 , a user plane entity as mentioned in any of claims 22 to 26, a policy control entity as mentioned in claim 27.

29. A computer program comprising program code to be executed by at least one processing unit of a session management entity, wherein execution of the program code causes the at least one processing unit to carry out a method as mentioned in any of claims 1 to 7.

30. A computer program comprising program code to be executed by at least one processing unit of a user plan entity, wherein execution of the program code causes the at least one processing unit to carry out a method as mentioned in any of claims 8 to 13.

31. A computer program comprising program code to be executed by at least one processing unit of a policy control entity, wherein execution of the program code causes the at least one processing unit to carry out a method as mentioned in claim 14.

32. A carrier comprising the computer program of any of claims 29 to 31, wherein the carrier is one of an electronic signal, optical signal, radio signal, and computer readable storage medium.