Patent Description:
The Traffic Detection Function, TDF, was introduced in the 3rd Generation Partnership Project, 3GPP, Release <NUM>. The TDF is a functional entity that performs application detection and control through different enforcement actions (for example gating, QoS, and reporting of a detected application and its service data flow description) on a per application basis. The Sd reference point was defined between the TDF and the Policy and Charging Rules Function, PCRF, allowing the PCRF to send subscriber session data and Application Detection and Control, ADC, rules to the TDF, and optionally allowing application detection and reporting from the TDF to the PCRF.

In 3GPP Release <NUM>, as part of Control User Plane Separation, the TDF was split into a control plane function (TDF-C) and a user plane function (TDF-U), and a new Sxc reference point was defined between them.

However, in the 5th Generation, <NUM>, network architecture, defined in 3GPP Release <NUM>, the TDF functional entity does not exist, and therefore neither does the Sd reference point to the PCRF. In such a network, therefore, the TDF is a network function that is deployed in the N6 (SGi) reference point and is out of 3GPP scope. The problem with this is that, in order to perform its tasks, the TDF will need information from the Policy Control Function, PCF, specifically subscriber session information and ADC rules.

<CIT> relates to service type and device type-based policy and charging control.

<NPL>, defines the Stage <NUM> procedures and Network Function Services for the <NUM> system architecture which is described in the TS <NUM> and for the policy and charging control framework which is described in TS <NUM>.

<CIT> relates to dynamic provision of application related sponsored data connectivity.

<NPL>, defines the Stage <NUM> system architecture for the <NUM> System.

This has the advantage that it allows a Traffic Detection Function (or Traffic Detection Function User plane) to be integrated with the core network, so that it can receive the network data that it requires to perform its intended functions.

The Traffic Detection Function (or Traffic Detection Function User plane) support an Event Exposure service, and an analytics entity (namely the NWDAF in <NUM>) can act as the main consumer for that service. This will allow the network operator to receive events directly from the TDF (or TDF-U).

<FIG> shows a 5th Generation core (5GC) network architecture <NUM>.

Specifically, <FIG> shows the relevant parts of the network architecture <NUM> comprising: a Unified Data Repository (UDR) <NUM>, with a service-based interface Nudr; a Network Exposure Function (NEF) <NUM>, with a service-based interface Nnef; a Network Data Analytics Function (NWDAF) <NUM>, with a service-based interface Nnwdaf; an Application Function (AF) <NUM>, with a service-based interface Naf; a Policy Control Function (PCF) <NUM>, with a service-based interface Npcf; a Charging Function (CF) <NUM>, with a service-based interface Nchf; an Access and Mobility Management Function (AMF) <NUM>, with a service-based interface Namf; a Session Management Function (SMF) <NUM>, with a service-based interface Nsmf; and a User Plane Function (UPF) <NUM>, with an N4 reference point between the UPF and the SMF.

The most relevant architectural aspects for present purposes are the PCF (Policy Control Function), SMF (Session Management Function), and UPF (User Plane Function).

The Policy Control function (PCF) supports different functionalities, for example a unified policy framework to govern network behaviour, provides policy rules to Control Plane function(s) to enforce them, and accesses subscription information relevant for policy decisions in a Unified Data Repository (UDR).

The Session Management function (SMF) supports different functionalities, for example Session Establishment, modify and release, and policy related functionalities such as termination of interfaces towards Policy control functions, Charging data collection, support of charging interfaces and control and coordination of charging data collection at the UPF.

The User Plane function (UPF) supports handling of user plane traffic, including packet inspection, packet routing and forwarding (including traffic steering), traffic usage reporting, and Quality of Service (QoS) handling for the user plane (for example Uplink and/or Downlink rate enforcement).

<FIG> illustrates a development of the architecture shown in <FIG>.

Specifically, <FIG> shows how a Traffic Detection Function (TDF) <NUM> can be integrated into the 5GC architecture.

The architecture shown in <FIG> includes elements that are similar to those shown in <FIG>, except as described in more detail below. Thus, the UPF <NUM> is connected over the N3 reference point to the Radio Access Network (RAN) <NUM>, which is provided to allow devices such as the User Equipment (UE) <NUM> to connect to the network.

The UPF <NUM> is connected to the SMF <NUM> over the N4 reference point. The PCF <NUM> is provided with a service <NUM>, identified as Npcf_SMPolicyControl.

The TDF <NUM> is connected over an N6 reference point to the UPF <NUM>, and is also connected over an N6 reference point to a data network <NUM>.

In accordance with this disclosure, the PCF <NUM> is extended with a service <NUM>, identified as Npcf_TDFPolicyControl, which is provided to allow a consumer to retrieve from the PCF both subscriber session information and Application Detection and Control (ADC) rules.

Further, the TDF <NUM> is allowed to be the consumer for the PCF service <NUM> mentioned above. In other embodiments, other consumers are possible, for example any Service Function (SF) in the SGi Local Area Network (SGi-LAN).

Allowing the TDF <NUM> to retrieve subscriber session information and ADC rules from the PCF means that it can be integrated in the <NUM> architecture and can receive the network data that it needs to perform its tasks.

<FIG>, made up of <FIG> and <FIG>, is a signalling diagram, illustrating the messages that flow between network functions in operation of the NpcC TDFPolicyControl service, where the network functions have been described with reference to <FIG> or <FIG>.

<FIG> and illustrates the case where the TDF <NUM> receives the subscriber session information and the ADC rules from the PCF <NUM> that is handling the subscriber's Protocol Data Unit (PDU) session. By way of illustration only, <FIG> shows an example use case, where the TDF <NUM> is used in order to run video optimization based on the Radio Access Technology (RAT) type for YouTube™ application traffic. In this illustrated example, the PCF <NUM> discovers the TDF <NUM> when the subscriber's PDU session is established. In an alternative embodiment, the TDF <NUM> could discover the PCF <NUM>, by the UPF <NUM> sending the PCF identifier (for example the IP address of the PCF) to the TDF.

In steps <NUM> and <NUM>, the UE <NUM> triggers the PDU session establishment, by sending a PDU Session Establishment Request to the AMF <NUM>, and by the AMF selecting an SMF <NUM> and triggering the Nsmf PDU Session Create message. It will be appreciated that the sequence diagram in <FIG> does not include all of the signalling messages that are involved in the PDU Session Establishment procedure, but these will be understood by the skilled reader.

In step <NUM>, the SMF <NUM> triggers an Npcf_SMPolicyControl_Create Request message to the PCF <NUM> to retrieve Session Management (SM) policies for the user PDU session.

In step <NUM>, the PCF <NUM> triggers an Nudr_DM_Query Request message to the UDR <NUM> to retrieve the policy data for this user PDU session.

In step <NUM>, the UDR <NUM> answers the PCF with an Nudr_DM_Query Response message including the Subscriber Policy Data. In particular, the UDR indicates to the PCF that a TDF is required for the subscriber's PDU session, and in this particular embodiment it does this by means of returning information identifying the TDF, for example the IP address of the TDF <NUM>.

In step <NUM>, the PCF <NUM> generates Policy Charging and Control (PCC) rules for the SMF <NUM>, and Application Detection and Control (ADC) rules for the TDF <NUM>, based on the Subscriber Policy Data.

In step <NUM>, based on the above, the PCF <NUM> triggers an Npcf_TDFPolicyControl HTTP POST message to the target TDF <NUM>, which it determines from the information identifying the TDF <NUM>, for example the IP address of the TDF as described above.

The body of the HTTP POST message includes subscriber session information and the ADC rules generated by the PCF.

Thus, in this illustrated embodiment, the PCF <NUM> discovers the TDF <NUM>. In an alternative embodiment, the TDF discovers the PCF. This is achieved by the UPF <NUM> sending the PCF identifier (for example the IP address of the PCF <NUM>) to the TDF <NUM>. In this case, the UPF determines which Service Functions (SFs) are in the chain indicated by the trafficSteeringPolicyldentifier (in this case a TDF), and gives instructions to the TDF so that it can subscribe to the new PCF Npcf_TDFPolicyControl service <NUM> shown in <FIG>. In order to do so, the UPF triggers an Naf HTTP POST message to the TDF, including in the body the PCF identifier and the information that is required to allow the TDF to identify the subscriber session, for example the external user identity (externalld or Global Public Subscription Identifier, GPSI) and/or the IP address of the UE.

Returning to the embodiment shown in <FIG>, in step <NUM> the TDF creates a subscriber session and stores both the subscriber session information and the ADC rules. Then, in step <NUM>, the TDF answers back to the PCF with a Npcf_TDFPolicyControl <NUM> OK successful response.

In step <NUM>, the PCF triggers an Npcf_SMPolicyControl_Create Response message to the SMF <NUM>, including the PCC rules to be applied for the subscriber's PDU session.

In step <NUM>, the SMF selects the UPF <NUM>, and triggers a Packet Forwarding Control Protocol (PFCP) Session Establishment Request message to the UPF <NUM>, including the corresponding rules, for example the Packet Detection Rules (PDRs), Forwarding Action Rules (FARs), QoS Enhancement Rules (QERs) and Usage Reporting Rules (URRs).

In step <NUM>, the UPF stores the PDRs/FARs/QERs/URRs, and answers back to the SMF with a PFCP Session Establishment Response message.

In step <NUM>, by way of example, the user opens the YouTube™ application.

In step <NUM>, the UPF uses the PCC rules to detect YouTube™ traffic and to apply the corresponding enforcement actions. Specifically, detection is based on matching the incoming packets with a PDR with Packet Detection Information (PDI) of type application with appld=YouTube, and having as an enforcement action a steering rule to forward this traffic towards the N6 interface (for example according to a FAR which includes as Forwarding Action the N6 interface, or alternatively through a trafficSteeringPolicyldentifier pointing to the TDF). Thus, in step <NUM>, the traffic is directed from the UPF <NUM> to the TDF <NUM>.

In step <NUM>, the TDF uses the ADC rules received in step <NUM> above to detect YouTube™ traffic and to apply the corresponding enforcement actions, for example to apply video optimization for YouTube™ traffic based on the Subscriber Session information received in step <NUM> above (for example the RAT-Type, location, etc).

In step <NUM>, the TDF then directs the YouTube™ traffic to the relevant application server <NUM>.

Thus, the Policy Control Function (PCF) is extended with a service (which in this example is given the name Npcf_TDFPolicyControl), which allows a consumer, for example the Traffic Detection Function (TDF), to retrieve from the PCF both the subscriber session parameters and the ADC rules.

In the illustrated embodiment, discovery of the PCF (that is, how the consumer, such as the TDF, knows which PCF handles the user's PDU session), takes place by the UPF sending the PCF identifier (for example the IP address of the PCF) to the consumer. An alternative mechanism is for the PCF to discover the consumer when the user's PDU session is established.

<FIG> illustrates a further development of the architecture shown in <FIG>. Specifically, the architecture shown in <FIG> has several features in common with <FIG>, and those features are indicated by the same reference numerals. The architecture shown in <FIG> is therefore capable of operating in the manner described in <FIG>.

In addition, the TDF <NUM> provides support for an Event Exposure service. Thus, as shown in <FIG>, the TDF <NUM> supports an Event Exposure service, Ntdf_EventExposure, <NUM>, and the <NUM> analytics entity, the Network Data Analytics Function (NWDAF) <NUM> acts as the main consumer for that service. This allows the network operator to receive events directly from the TDF.

It has also been proposed, as part of Control User Plane Separation, that the TDF be split into a control plane function (TDF-C) and a user plane function (TDF-U), with a new Sxc reference point was defined between them.

The present disclosure also describes a mechanism to allows the TDF functionality to be integrated into the <NUM> architecture and to receive the network data needed to perform the TDF tasks.

Thus, <FIG> illustrates a development of the architecture shown in <FIG>.

Specifically, <FIG> shows how the TDF functionality can be integrated into the 5GC architecture. The architecture shown in <FIG> includes elements that are similar to those shown in <FIG>, except as described in more detail below.

In this example, the functionality of the TDF is split into a user plane function (i.e. the Traffic Detection Function User plane, or TDF-U) <NUM>, and a control plane function (i.e. the Traffic Detection Function Control plane, or TDF-C), with the latter function being included in the SMF <NUM>.

As before, the UPF <NUM> is connected over the N3 reference point to the Radio Access Network (RAN) <NUM>, which is provided to allow devices such as the User Equipment (UE) <NUM> to connect to the network.

The UPF <NUM> is connected to the SMF <NUM> over the N4 reference point, and the SMF <NUM> is connected to the PCF <NUM>. More specifically, the SMF <NUM> is provided with a service <NUM>, identified as Nsmf_N4, to which the UPF <NUM> connects, and the PCF <NUM> is provided with a service <NUM>, identified as Npcf_SMPolicyControl, to which the SMF <NUM> connects.

The TDF-U <NUM> is connected over an N6 reference point to the UPF <NUM>, and is also connected over an N6 reference point to a data network <NUM>.

In accordance with this disclosure, the SMF <NUM> is extended with a service <NUM>, identified as Nsmf_TDFN4, in order to allow a consumer to retrieve from the SMF both subscriber session information and the rules to be applied. Further, the TDF-U <NUM> is allowed to be the consumer for the SMF service <NUM> mentioned above. In other embodiments, other consumers are possible, for example any Service Function (SF) in the SGi Local Area Network (SGi-LAN).

Allowing the TDF-U <NUM> to retrieve subscriber session information and ADC rules from the SMF means that it can be integrated in the <NUM> architecture and can receive the network data that it needs to perform its tasks.

<FIG>, made up of <FIG> and <FIG>, is a signalling diagram, illustrating the messages that flow between network functions in operation of the Nsmf_TDFN4 service, where the network functions have been described with reference to <FIG> or <FIG>.

<FIG> illustrates the case where the TDF-U <NUM> receives the subscriber session information and the detection and enforcement rules directly from the SMF <NUM> that is handling the subscriber's Protocol Data Unit (PDU) session. This implies that the SMF <NUM> includes the TDF-C functionality.

By way of illustration only, <FIG> shows an example use case, where the TDF-U <NUM> is used in order to run video optimization based on the Radio Access Technology (RAT) type for YouTube™ application traffic. In this illustrated example, the SMF <NUM> discovers the TDF-U <NUM> when the subscriber's PDU session is established.

In step <NUM>, the UDR <NUM> answers the PCF with an Nudr_DM_Query Response message including the Subscriber Policy Data. In particular, the UDR indicates to the PCF that a TDF-U is required for the subscriber's PDU session, and in this particular embodiment it does this by means of returning information identifying the TDF, for example the IP address of the TDF-U <NUM>.

In step <NUM>, the PCF <NUM> generates Policy Charging and Control (PCC) rules, based on the Subscriber Policy Data. The PCC rules indicate that a TDF-U is required for the subscriber's PDU session, for example by means of including information identifying a TDF-U (that is, a tdfld), for example the IP address of the TDF-U.

In step <NUM>, the PCF triggers an Npcf_SMPolicyControl_Create Response message to the SMF <NUM>, with the message including the PCC rules to be applied for the subscriber's PDU session.

In step <NUM>, based on the PCC rules received, the SMF <NUM> selects a UPF <NUM> (as described in the current 3GPP Rel15 procedures) and also selects a TDF-U to handle the user plane traffic for the susbcriber's PDU session.

In step <NUM>, the SMF <NUM> triggers an Nsmf_N4 HTTP POST message towards the selected UPF <NUM> by including the corresponding rules, for example the Packet Detection Rules (PDRs), Forwarding Action Rules (FARs), QoS Enhancement Rules (QERs) and Usage Reporting Rules (URRs). For example, the N4 reference point between the UPF and the SMF using the PFCP protocol may be replaced by a service-based interface, for example called Nsmf_N4.

In step <NUM>, the UPF <NUM> stores the PDRs/FARs/QERs/URRs and answers back to the SMF <NUM> with a Nsmf_N4 HTTP <NUM> OK successful response.

In step <NUM>, the SMF triggers an Nsmf_TDFN4 HTTP POST message to the target TDF-U (determined by the identifying information tdfld, which could be just the IP address of the TDF-U). The body of the HTTP POST message includes both the subscriber session information and the corresponding PDRs/FARs/QERs/URRs.

In step <NUM>, the TDF-U <NUM> creates a subscriber session and stores the subscriber session information and the corresponding PDRs/FARs/QERs/URRs.

In step <NUM>, the TDF-U answers back to the SMF <NUM> with a Nsmf_TDFN4 <NUM> OK successful response.

In step <NUM>, the UPF <NUM> uses the received rules to detect YouTube™ traffic and to apply the corresponding enforcement actions. Specifically, detection is based on matching the incoming packets with a PDR with Packet Detection Information (PDI) of type application with appld=YouTube, and having as an enforcement action a steering rule to forward this traffic towards the N6 interface (for example according to a FAR which includes as Forwarding Action the N6 interface, or alternatively through a trafficSteeringPolicyldentifier pointing to the TDF). Thus, in step <NUM>, the traffic is directed from the UPF <NUM> to the TDF-U <NUM>.

In step <NUM>, the TDF-U uses the PDRs/FARs/QERs/URRs received in step <NUM> above to detect YouTube™ traffic and to apply the corresponding enforcement actions, for example to apply video optimization for YouTube™ traffic based on the Subscriber Session information received in step <NUM> above (for example the RAT-Type, location, etc).

In step <NUM>, the TDF-U then directs the YouTube™ traffic to the relevant application server <NUM>.

Thus, in the TDF-U scenario, it is disclosed that the existing TDF-C functionality be integrated into the SMF and that the SMF be extended with a new service (called Nsmf_TDFN4 herein) to allow the TDF-U to retrieve from the SMF both subscriber session parameters and TDF-U rules.

In order to facilitate SMF discovery (that is, how the consumer, for example the TDF-U, knows which SMF is handling the user's PDU session), a mechanism is described where the SMF allocates the TDF-U instance when the user's PDU session is established.

In addition, the TDF-U <NUM> provides support for an Event Exposure service. Thus, as shown in <FIG>, the TDF-U <NUM> supports an Event Exposure service, Ntdf_EventExposure, <NUM>, and the <NUM> analytics entity, the Network Data Analytics Function (NWDAF) <NUM> acts as the main consumer for that service. This allows the network operator to receive events directly from the TDF.

<FIG> is a block diagram, illustrating the main functional components of a core network node <NUM> in the wireless communication network described herein. The core network node <NUM> may be used to implement one or more of the core network functions, such as those shown in <FIG>, <FIG>, <FIG>, <FIG> or <FIG> herein. Any of the core network functions may be implemented by a single core network node <NUM>, or may be distributed among two or more core network nodes, each having the form of the node <NUM>.

The core network node <NUM> comprises a communications module <NUM>, including a network interface circuit to enable communications with other core network nodes and/or with base stations in the radio access network, as required.

The core network node <NUM> also comprises a data processing and control unit <NUM>, which includes a processor <NUM> and a memory <NUM>.

The processor <NUM> controls the operation of the core network node <NUM>. The processor <NUM> may comprise one or more microprocessors, hardware, firmware, or a combination thereof.

The memory <NUM> may comprise both volatile and non-volatile memory for storing computer program code and data needed by the processor <NUM> for operation.

Claim 1:
A Policy Control Function, PCF, (<NUM>) for use in a <NUM> core network, wherein the PCF (<NUM>) is configured to:
receive (<NUM>), from a Session Management Function, SMF (<NUM>), a request for session management policies applying to a subscriber session;
send (<NUM>), to a Unified Data Repository, UDR (<NUM>), a query request for policy data relating to the subscriber session;
receive (<NUM>) policy data from the UDR (<NUM>) in response to the query request, wherein the policy data indicates that a Traffic Detection Function, TDF (<NUM>), is required for the subscriber session;
generate (<NUM>), based on the retrieved policy data, i) Application Detection and Control rules relating to the subscriber session, and ii) Policy Charging and Control rules relating to the subscriber session;
send (<NUM>), to a TDF (<NUM>), subscriber session information and the Application Detection and Control rules relating to the subscriber session; and
send (<NUM>), to the SMF (<NUM>), the Policy Charging and Control rules.