CROSS REFERENCE TO RELATED APPLICATIONS

This application is a 35 U.S.C. § 371 national stage application of PCT International Application No. PCT/EP2017/076356 filed on Oct. 16, 2017, the disclosure and content of which is incorporated by reference herein in its entirety.

TECHNICAL FIELD

Embodiments herein relate generally to a Radio Access Management Function (RAMF), a method performed by the RAMF, a Session Management Function (SMF), a method performed by the SMF, a User Equipment (UE) and a method performed by the UE. More particularly the embodiments herein relate to handling connectivity to a Data Network, (DN).

BACKGROUND

In the present development of mobile systems and in particular for the Fifth Generation (5G), the network is partitioned in a (Radio) Access Network ((R)AN) and a Core Network (CN) which is further divided in one part handling mobility (the whereabouts of devices, UEs) and another part handling the connectivity (sessions) for UEs to data networks.

For the purpose of gaining connectivity the same identity (the identity may be e.g. an International Mobile Subscriber Identity (IMSI)) is used for authentication and/or authorization for both mobility and connectivity, while there is readily a possibility to have a second authentication for session connectivity. The data network serving the connection handles the second authentication, so it cannot be used within the CN/connectivity handling for any other purpose than conforming that the user is allowed to access the data network.

The 5G point-to-point and service based architecture for the roaming case is depicted inFIG. 1andFIG. 2(ref. 3GPP TS 23.501 v1.4.0).FIG. 1illustrates a non-roaming 5G System architecture with a home routed scenario using a reference point representation.FIG. 2illustrates a roaming 5G System architecture with a home routed scenario using a reference point representation.

FIG. 1illustrates a UE101connected to a (Radio) Access Network ((R)AN)103. The (R)AN103is connected to an Access and Mobility Management Function (AMF)105via a N2 reference point. The UE101is connected to the AMF105via a N1 reference point. The AMF105is adapted to be connected to an SMF108via a N11 reference point. The SMF108is adapted to be connected to two User plane Functions (UPF)125via a respective N4 reference point. The (R)AN103is adapted to be connected one of the UPFs125via a N3 reference point. The two UPFs125are adapted to be connected to each other via a N9 reference point. Each UPFs125is adapted to be connected to a respective DN120via respective N6 reference point. The DN may be e.g. operator services, Internet access or 3rd party services. The AMF105is adapted to be connected to an Authentication Server Function (AUSF)128via a N12 reference point. The AMF105is adapted to be connected to a Unified Data Management (UDM)130via a N8 reference point. The AUSF128is adapted to be connected to the UDM130via the N13 reference point. The SMF108is adapted to be connected to the UDM130via a N10 reference point. The SMF108is adapted to be connected to a Policy Control function (PCF)133via a N7 reference point. The PCF133is adapted to be connected to an Application Function (AF)135via a N5 reference point. The PCF133is adapted to be connected to the AMF105via a N15 reference point. A reference point may also be referred to as an interface.

FIG. 2illustrates a Visited Public Land Mobile Network (VPLMN)200and a Home Public Land Mobile Network (HPLMN)210. The dotted vertical line illustrate the division between the VPLMN200and the HPLMN210, where the VPLMN200is on the left side of the dotted vertical line and the HPLMN210is on the right side of the dotted vertical line.FIG. 2illustrates the UE101adapted to be connected to the (R)AN103. The (R)AN103is adapted to be connected to one UPF125via the N3 reference point. The UE101is adapted to be connected to the AMF105via the N1 reference point. The (R)AN103is adapted to be connected to the AMF105via the N2 reference point. The AMF105is adapted to be connected to the NSSF106via the N22 reference point. Two UPFs125are adapted to be connected to each other via the N9 reference point, where one UPF125is in the VPLMN200and the other UPF125is in the HPLMN210. Each UPF125is adapted to be connected to a respective SMF108via a respective N4 reference point. Thus, there are two SMFs108, where one SMF108is in the VPLMN200and therefore illustrated as a V-SMF and the other SMF108is in the HPLMN210and therefore illustrated as a H-SMF. The V-SMF and the H-SMF108are adapted to be connected to each other via a N16 reference point. The V-SMF108is adapted to be connected to the AMF105via the N11 reference point. The UPF125in the HPLMN210is adapted to be connected to a DN120via a N6 reference point. A PCF133is located in the VPLMN200and is therefore illustrated as a vPCF and another PCF133is located in the HPLMN210and is therefore illustrated as an H-PCF. The PCF133in the VPLMN200is adapted to be connected to the AMF105via a N15 reference point. The H-PCF133in the HPLMN210is adapted to be connected to the vPCF133in the VPLMN200via the N24 reference point. The H-SMF108in the HPLMN210is adapted to be connected to the H-PCF133via the N7 reference point. A UDM130is located in the HPLMN210and is adapted to be connected to the AMF105in the VPLMN200via the N8 reference point and to the SMF108in the HPLMN210via a N10 reference point. An AUSF128is located in the HPLMN210and is adapted to be connected to the UDM130via the N13 reference point and to the AMF105in the VPLMN200via the N12 reference point The H-PCF133in the HPLMN210is adapted to be connected to the AF135via the N5 reference point.

The VPLMN200comprises at least some of the following entities: UE101, (R)AN130, UPF125, AMF105, V-SMF108, NSSF106and vPCF133. The HPLMN210comprises at least some of the following entities: UPF125, DN120, H-SMF108, AUSF128, H-PCF133, AF135and UDM13.

The UDM130in the HPLMN210hosts the UE101authentication and basic authorization data. The N8 reference point (between the AMF105and the UDM130) provides the authentication/authorization for the radio access and mobility part, whereas the N10 reference point (between the UDM130and the SMF108) provides the necessary authentication/authorization for sessions towards a DN120. The 3GPP TS 23.501 v1.4.0 has the following statements about how slices can be formed:

The network (e.g. a PLMN) can also be divided in so called slices. A single UE101can simultaneously be served by one or more Network Slice instances via a 5G-AN. The AMF105instance serving the UE101logically belongs to each of the Network Slice instances serving the UE101, i.e. this AMF105instance is common to the Network Slice instances serving a UE101.

A Protocol Data Unit (PDU) session belongs to one and only one specific Network Slice instance per PLMN. Different Network Slice instances do not share a PDU session, though different slices may have slice-specific PDU sessions using the same Data Network Name (DNN). A PDU session may be described as an association between the UE101and the DN120.

From this, it is seen that the architecture supports a strict separation of the responsibilities for radio access and mobility (at the AMF105) and the handling of the connectivity (at the SMF108). Notably the Third Generation Partnership Project (3GPP) has defined separate reference points for acquiring subscription data for the RAN access/mobility (AMF105uses N8) and the subscription data for connectivity (SMF108uses N10). Still, the 3GPP work progresses under the assumption that the same identity is used for both the RAN access/mobility and the connectivity.

A 5G solution to direct the access connectivity to the appropriate anchor involves three steps performed by the RAN103:

Step 1) The selection function is based on if the device supports 5GC or not (indicated by the UE101at attach over Long Term Evolution (LTE) Radio Resource Control (RRC)). A selection is performed by the eNB among the Evolved Packet core (EPC) and Next Generation Core (5GC). The 5G gNB in the RAN103does not perform any selection, it uses only 5GC.

Step 2) A slice selection using Non Access Stratum (NAS) Node Selection Function (NNSF), using eitherDedicated Core Network (DÉCOR), orevolved DÉCOR (eDECOR), orMulti-Operator Core Network (MOCN), orsimilar, pending 3GPP 5G Core rel15+ standards

Step 3) Selection of instance within a pool inside each slice, for load balancing across pool members.

Considered from a device perspective, there are practical cases where many small devices would get a poor cost/benefit ratio:a) from being required to have its own UE101(device manufacturing and power consumption),b) by the legacy requirement that the device need a Subscriber Identity Module (SIM) with an operator controlled IMSI (the device owner need to rely on the operator to manage the devices), interfacec) from the need to decouple its own mobility from the UE101(assuming the device is decoupled from the UE101, it is a limitation to tie the device to one specific UE101).

The term “device” or “small device” used above refers to a device which is located behind a UE101. Such device has typically no own connection to the DN120, but connects via the UE101connection. An example of a device is a GPS device, a sport watch, a camera etc.

Lacking in the present architecture is:The organization owning/maintaining the small devices to add/remove/block/upgrade the devices in a cost-effective manner.A possibility to enable the management of the small devices to be independent from a particular operator's domain.To allow the small device to establish its specialized connectivity, independent from the UE101per se.

Therefore, there is a need to at least mitigate or solve these issues.

SUMMARY

An objective of embodiments herein is therefore to obviate at least one of the above disadvantages and to improve handling of connectivity to a DN.

According to a first aspect, the object is achieved by a method performed by a Radio Access Management Function (RAMF) for handling connectivity to a DN. The RAMF receives, from a UE, a request associated with connectivity to the DN for an application having a subscription ID. The RAMF selects, based on at least a part of the subscription ID, which SMF the request should be forwarded to, and forwards the request to the selected SMF.

According to a second aspect, the object is achieved by a method performed by a SMF for handling connectivity to a DN. The SMF receives, from a RAMF, a request associated with connectivity to the DN for an application having a subscription ID. The SMF determines that the request is accepted, and transmits, to the RAMF, accept information indicating the accept of the request, a temporary ID, a SMF ID and a connection ID.

According to a third aspect, the object is achieved by a RAMF for handling connectivity to a Data Network. The RAMF is adapted to receive, from a UE, a request associated with connectivity to the DN for an application having a subscription ID. The RAMF is adapted to select, based on at least a part of the subscription ID, which SMF the request should be forwarded to, and to forward the request to the selected SMF.

According to a fourth aspect, the object is achieved by a SMF for handling connectivity to a DN. The SMF is adapted to receive, from a RAMF, a request associated with connectivity to the DN for an application having a subscription ID. The SMF is adapted to determine that the request is accepted, and to transmit, to the RAMF, accept information indicating accept of the request, the temporary ID, a SMF ID and a connection ID.

Thanks to the subscription ID which is a dedicated user ID for connectivity, the subscription ID can be used for other purposes in addition to confirming that the application is granted access to the DN, and thus, the handling of connectivity to a DN is improved.

Embodiments herein afford many advantages, of which a non-exhaustive list of examples follows:

With a separation of identities for RAN access/mobility versus identities for connectivity the mobility and connectivity aspects can be separated enabling an array of possibilities.

An advantage of the embodiments herein is that one UE may serve multiple applications/secondary devices without any tight integration.

Another advantage of the embodiments herein is that an application/secondary device access can be tailored independent from the UE details.

A further advantage of the embodiments herein is that the management of applications/secondary devices can be closely associated with the organization that manages the applications/secondary devices.

Additionally, the application/secondary device can potentially be used together with any UE that supports the local communication with the application/secondary device.

An advantage of the embodiments herein is that the operation and management of the RAN access domain and the core network domain are independent.

The embodiments herein provide advantages for the application/secondary device, such as the UE may conduct a local authorization for applications/devices to allow/deny the use of connectivity.

The communication between the secondary device and the UE can be based on any technology.

The embodiments herein are not limited to the features and advantages mentioned above. A person skilled in the art will recognize additional features and advantages upon reading the following detailed description.

