CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Submission Under 35 U.S.C. § 371 for U.S. National Stage Patent Application of International Application Number: PCT/EP2017/067043, filed Jul. 6, 2017 entitled “USER DATA TRANSPORTED OVER NON-ACCESS STRATUM,” the entirety of which is incorporated herein by reference.

TECHNICAL FIELD

The invention relates to control of user data transported over the Non-Access Stratum (NAS) of a telecommunications network, in particular a Third Generation Partnership Project (3GPP) network. In particular, the invention relates to authorization and/or rate control of user data transported over the NAS.

BACKGROUND

A policy framework for Fifth Generation (5G) networks is specified in 3GPP Technical Specification (TS) 23.501 V1.0.0. The policy framework functionality comprises the functions of a Policy Control Function (PCF), an Access and Mobility Policy Enforcement Function (AMPEF), an Online Charging System (OCS) and an Application Function (AF).

FIG. 1shows the policy framework architecture (non-roaming) in a 5G system, which is based on the current Policy Control and Charging (PCC) framework as defined for the Enhanced Packet Core (EPC) in 3GPP TS 23.203 v14.3.0.

The policy framework architecture for 5G networks provides charging and policy control for packet data flows exchanged over a user plane between a User Equipment (UE) and a User Plane Function (UPF), neither of which is shown inFIG. 1. The UPF interacts with a Session Management Function (SMF)100via an N4 interface that is not part of the policy framework architecture. The UPF also provides access and mobility policy control for the UE accessing the 5G network.

The PCF102provides policy rules to a Policy Control Enforcement Function (PCEF), which is distributed between the SMF100and the UPF and includes both charging and policy control information for detected traffic. The SMF100may send related instructions towards the UE so that the UE can apply Quality of Service (QoS) control to an uplink (UL) user plane as instructed by the PCF102.

Additionally, the PCF102provides access and mobility policies and UE policies to an Access and Mobility Function (AMF)104for enforcement in the AMF104, Radio Access Network (RAN) or UE.

Access and mobility policies refer to Service Area Restrictions and Radio Access Technology (RAT)/Frequency Selection Priority (RFSP) indicators. Service Area Restrictions indicate areas where the UE is permitted (or not permitted) to initiate a communication session with the network. RAT/RFSP allows a RAN to redirect UEs to different frequency layers or RATs. Enforcement of these policies is typically performed in the RAN. 3GPP TS 23.501, clause 5.3.4.1.1 specifies these mobility restrictions, and annex A.4.1.2 specifies the related procedure.

UE policies refer to access network discovery and selection policies (for the UE to select a non-3GPP access and for the traffic to be routed on that access) and UE Route Selection policies (for the UE to decide how the outgoing traffic should be routed).

These access and mobility policies and UE policies do not apply to user data sent via the NAS transport.

In 3GPP Release 13, as part of the Cellular Internet of Things (CIoT) functionality, it was agreed to introduce Control Plane CIoT Evolved Packet System (EPS) Optimization procedures. The UE and AS can transfer data over the NAS Packet Data Units (PDUs) for both Internet Protocol (IP) and Non-IP data types.

This solution makes sense for the cases where the establishment of resources for the transport of user data over the user plane can be avoided. This possibility simplifies the architecture, limiting the number of involved entities and optimizing the resources.

In order to control CIoT application traffic, 3GPP has defined a user data rate control mechanism for network traffic sent from/to a UE in the CIoT EPS Optimization scenarios mentioned above. Two procedures are defined: Serving Public Land Mobile Network (PLMN) rate control (see clause 4.7.7.1 in 3GPP TS 23.401); and Access Point name (APN) rate control (see clause 4.7.7.2 in 3GPP TS 23.401).

According to these procedures the network may control the number of messages sent to/from a UE within the PLMN (Serving PLMN rate control) or per APN (APN rate control).

APN rate control is controlled by the Service Capability Exposure Function (SCEF)/Packet Gateway (PGW) based on the configuration for both UL and DL messages. Serving PLMN rate control is controlled by the Mobility Management Entity (MME) and the SCEF/PGW configuration is determined in the MME and transported to the SCEF/PGW.

SUMMARY

The APN Rate Control and Serving PLMN Rate Control were designed in 4G to protect the network from overload in case of massive communications, especially when Control Plane data (NAS transport) is used. However, the inventors have appreciated that they are not useful for providing different subscription based data package plans and protecting from certain peak load situations.

It has been considered to transmit different kinds of payload types over NAS (e.g. Session Management (SM) signalling, Short Messaging Service (SMS) etc.). For example, one proposal is that when a UE needs to transmit a payload over the NAS, the UE creates an NAS Transport message indicating Payload Type (e.g. SMS, SM signalling), additional forwarding information, if needed, and the actual Payload. In this environment, the protection from certain peak load situations becomes more important.

Although only SMS & SM signalling is currently being discussed, the inventors have appreciated that the same solution (NAS transport) can be used when a UE and/or Application Server (AS) wants to exchange a small amount of data that does not require that the network establish the conditions for the user plane to be exchanged. These scenarios may not be limited to massive Internet of Things (IoT) cases. Instead individual UEs may run applications that make use of these mechanisms to exchange relevant data.

The inventors have appreciated that there is no dynamic and/or user based authorization and/or rate control for transmission of network traffic over the NAS.

There is no Policy and Charging Rules Function (PCRF) involvement defined in 3GPP when user data is transported using NAS protocol as user data transport protocol, for example over the Control Plane. The inventors have further appreciated that a motivation for not defining dynamic rate control of traffic over the NAS is that IoT scenarios defined in 3GPP Release 13 were considered scenarios focused on the support of massive “things” that transport very small amounts of data. Having a dynamic, user based authorization and/or rate policy would have been considered unnecessary at that time under those conditions. It is noted that when a UE (or user) stays below its APN rate control limit, it may still consume its whole daily allowance in just a few seconds, and this would be unnoticeable by the network in time to react.

Considering the current mechanisms defined for 4G, any UE (or user) can send and/or receive any amount of data over the NAS that does not surpass the configured rate control values, regardless of whether it is a fraudulent user, an abuser, or of the user's data plan in the user's subscription.

In addition, a network operator cannot take any specific action on such a user (e.g. redirect the traffic to a less optimized route, force the UE to transport over User Plane for Application traffic, use a different RAT type or RFSP index, or disregard the exceeded traffic until a new period is initiated) if the allowed rate is surpassed in a specific time or under certain conditions. Controlling the allowed rate on a user basis and/or dynamically would help alleviate the peak load on the network and/or prevent the load becoming significant—if there is a large number of devices, potentially accessing in a time-synchronized manner, the peak load on the network may be high.

Also, the operator cannot authorize different payloads depending on the UE (user) subscription and specific conditions (e.g. SMS could be authorized only when the UE is in a certain location or area).

Finally, there is no mechanism to ingest data in the payload that can help the application in identifying specific treatment in the network.

Exemplary methods and apparatus disclosed herein are aimed at solving or at least mitigating one or more of the above problems, although other problems may also be solved.

According to an aspect of the invention, there is provided a network node for use as an Access Mobility Function, AMF, for controlling the transmission of user data over a non-Access Stratum, NAS, of a telecommunications network. The network node comprises a receiver, which may be a receiving means, configured to receive NAS policy control data from a Policy Control Function, PCF, the NAS policy control data identifying a user, being based on the user's subscription to the telecommunications network and comprising one or more authorization parameters identifying whether the user is permitted to transmit user data over the NAS. The receiver is further configured to receive from a User Equipment, UE, or an Application Server, AS, an NAS transmission request identifying the user and requesting transmission of user data over the NAS. The apparatus further comprises an NAS transmission authorizer, which may be an NAS transmission authorizing means, configured to control whether the transmission of the user data over the NAS should be authorized based on the authorization parameters and the NAS transmission request.

Optionally, the authorization parameters comprise one or more of: whether the user is permitted to transmit user data over the NAS; one or more payload types that the user is permitted to transmit over the NAS; an authorized rate at which the user may transmit the user data over the NAS; and a maximum number of authorized requests for the user.

Optionally, the NAS transmission request comprises data identifying a payload type to be transmitted, the NAS transmission authorizer being configured to authorize the request if the identified payload type is one of the one or more payload types in the authorization parameters.

Optionally, the authorization parameters comprise the authorized rate at which the user may transmit the user data over the NAS, the network node may further comprise an NAS transmission controller configured to control the transmission of the user data over the NAS based on the authorized rate.

Optionally, the authorized rate at which the user may transmit the user data over the NAS is a rate per Data Network Name, DNN, per Public Land Mobile Network, PLMN, and/or per network slice.

Optionally, the authorized rate at which the user may transmit the user data over the NAS comprises an uplink rate and/or a downlink rate.

Optionally, the NAS policy control data further comprises one or more enforcement actions and wherein the NAS transmission authorizer is configured to undertake one or more of the one or more enforcement actions if at least one of the authorization parameters is not met.

Optionally, the NAS policy control data further comprises one or more event triggers identifying one or more events, and the network node further comprises an event controlling means, which may be an event controller, configured to monitor transmission of the user data over the NAS and to control a transmission means, which may be a transmitter, to transmit to the PCF a request for updated NAS policy control data if one of the one or more events occurs.

According to the invention in an aspect, there is provided a method for controlling a network node for use as an Access Mobility Function, AMF, for controlling the transmission of user data over a non-Access Stratum, NAS, of a telecommunications network. The method comprises receiving, by a receiver, NAS policy control data from a Policy Control Function, PCF, the NAS policy control data identifying a user, being based on the user's subscription to the telecommunications network and comprising one or more authorization parameters identifying whether the user is permitted to transmit user data over the NAS. The method comprises receiving, by the receiver from a User Equipment, UE, or an Application Server, AS, an NAS transmission request identifying the user and requesting transmission of user data over the NAS. The method comprises controlling, by an NAS transmission authorizer, whether the transmission of the user data over the NAS should be authorized based on the authorization parameters and the NAS transmission request.

Optionally, the authorization parameters comprise one or more of: whether the user is permitted to transmit user data over the NAS; one or more payload types that the user is permitted to transmit over the NAS; an authorized rate at which the user may transmit the user data over the NAS; and a maximum number of authorized requests for the user.

Optionally, the NAS transmission request comprises data identifying a payload type to be transmitted, the method comprising authorizing, by the NAS transmission authorizer, the request if the identified payload type is one of the one or more payload types in the authorization parameters.

Optionally, the authorization parameters comprise the authorized rate at which the user may transmit the user data over the NAS, the method further comprising controlling, by an NAS transmission controller, the transmission of the user data over the NAS based on the authorized rate.

Optionally, the authorized rate at which the user may transmit the user data over the NAS is a rate per Data Network Name, DNN, per Public Land Mobile Network, PLMN, and/or per network slice.

Optionally, the authorized rate at which the user may transmit the user data over the NAS comprises an uplink rate and/or a downlink rate.

Optionally, the NAS policy control data further comprises one or more enforcement actions and wherein the method further comprises undertaking, by the NAS transmission authorizer, one or more of the one or more enforcement actions if at least one of the authorization parameters is not met.

Optionally, the NAS policy control data further comprises one or more event triggers identifying one or more events, and the method further comprises monitoring, by an event controller, transmission of the user data over the NAS, and controlling, by the event controller, a transmitter to transmit to the PCF a request for updated NAS policy control data if one of the one or more events occurs.

According to the invention in an aspect, there is provided a network node for use as a Policy Control Function, PCF, in a telecommunications network. The network node comprises a receiving means, which may be a receiver, configured to receive from an Access Mobility Function, AMF, a request for NAS policy control data, the request identifying a user of the telecommunications network. The network node comprises an NAS policy data determining means, which may be an NAS policy data determiner, configured to determine the NAS policy control data based on the user's subscription to the telecommunications network, the NAS policy control data identifying the user and comprising one or more authorization parameters identifying whether the user is permitted to transmit user data over a non-Access Stratum, NAS, of the telecommunications network. The NAS policy data determiner is further configured to control a transmitter to transmit the determined NAS policy control data to the AMF.

Optionally, the NAS policy data determiner is further configured to determine the NAS policy control data based on one or more dynamic conditions.

Optionally, the dynamic conditions comprise one or more of: a time at which the user data may be transmitted over the NAS; a Radio Access Technology, RAT, type; and a load on the telecommunications network.

Optionally, the one or more authorization parameters comprise one or more of: whether the user is permitted to transmit user data over the NAS; one or more payload types that the user is permitted to transmit over the NAS; an authorized rate at which the user may transmit the user data over the NAS; and a maximum number of authorized requests for the user.

Optionally, the authorized rate at which the user may transmit the user data over the NAS is a rate per Data Network Name, DNN, per Public Land Mobile Network, PLMN and/or per network slice.

Optionally, the authorized rate at which the user may transmit the user data over the NAS comprises an uplink rate and/or a downlink rate.

Optionally, the NAS policy control data further comprises one or more enforcement actions to be undertaken if at least one of the authorization parameters is not met.

Optionally, the NAS policy control data further comprises one or more event triggers identifying one or more events, and the receiver is configured to receive a request for updated NAS policy control data if one or more of the one or more events occurs, the network node further comprising an NAS policy updating means, which may be an NAS policy updater, configured to determine updated NAS policy control data based on the occurred event, and further configured to control the transmitter to transmit the updated NAS policy control data to the AMF.

According to the invention in an aspect, there is provided a method for controlling a network node for use as a Policy Control Function, PCF, in a telecommunications network. The method comprises receiving, by a receiver from an Access Mobility Function, AMF, a request for NAS policy control data, the request identifying a user of the telecommunications network. The method comprises determining, by a NAS policy data determiner, the NAS policy control data based on the user's subscription to the telecommunications network, the NAS policy control data identifying the user and comprising one or more authorization parameters identifying whether the user is permitted to transmit user data over a non-Access Stratum, NAS, of the telecommunications network. The method comprises controlling, by the NAS policy data determiner, a transmitter to transmit the determined NAS policy control data to the AMF.

Optionally, the method further comprises determining, by the NAS policy data determiner, the NAS policy control data based on one or more dynamic conditions.

Optionally, the dynamic conditions comprise one or more of: a time at which the user data may be transmitted over the NAS; a Radio Access Technology, RAT, type; and a load on the telecommunications network.

Optionally, the one or more authorization parameters comprise one or more of: whether the user is permitted to transmit user data over the NAS; one or more payload types that the user is permitted to transmit over the NAS; an authorized rate at which the user may transmit the user data over the NAS; and a maximum number of authorized requests for the user.

Optionally, the authorized rate at which the user may transmit the user data over the NAS is a rate per Data Network Name, DNN, per Public Land Mobile Network, PLMN and/or per network slice.

Optionally, the authorized rate at which the user may transmit the user data over the NAS comprises an uplink rate and/or a downlink rate.

Optionally, the NAS policy control data further comprises one or more enforcement actions to be undertaken if at least one of the transmission parameters is not met.

Optionally, the NAS policy control data further comprises one or more event triggers identifying one or more events, the method further comprising receiving, by the receiver, a request for updated NAS policy control data if one or more of the one or more events occurs; determining, by an NAS policy updater, updated NAS policy control data based on the occurred event; and controlling, by the NAS policy updater, the transmitter to transmit the updated NAS policy control data to the AMF.

According to the invention in an aspect, there is provided a computer program comprising instructions which, when executed on at least one processor, cause the at least one processor to carry out any method disclosed herein.

According to the invention in an aspect, there is provided a carrier containing the computer program mentioned above, wherein the carrier is one of an electronic signal, optical signal, radio signal, or non-transitory computer readable storage medium.

