Patent Description:
The present disclosure relates to Edge computing, and more particularly to supporting connection to a local Data Network (DN).

The Third Generation Partnership Project (3GPP) Fifth Generation (<NUM>) New Radio (NR) specification seeks to improve radio access to Data Networks (DNs), such as the internet, for larger numbers of User Equipment (UE) devices while reducing latency. In this regard, 3GPP SA2 is currently engaged in a study on Edge computing, which seeks to lower DN latency by locating computation and data storage closer to where it is needed. Edge computing promises to improve computation response times for distributed computing (e.g., cloud computing) and conserve bandwidth for DNs and access networks, such as a <NUM> System (5GS).

One of the key issues identified for supporting Edge computing in a 5GS, defined in 3GPP temporary document S2-<NUM>, is providing a mechanism to activate traffic routing towards a local DN. A use case is described where an Intermediate Session Management Function (I-SMF) is inserted because the current Session Management Function (SMF) or I-SMF serving a given UE does not support connection to a local DN. The use of I-SMF and how an I-SMF can be inserted or changed is specified in 3GPP Technical Specification (TS) <NUM> clause <NUM> and TS <NUM> clause <NUM>. The UE with a subscription supporting connection to this DN will only connect to the local DN when it is in a certain area. A key functionality for gaining connection to a local DN is to use an Uplink Classifier (UL CL), as further described in 3GPP TS <NUM> clause <NUM>.

One existing solution for routing traffic towards a local DN is to use a Local Area DN (LADN) (see <NUM> clause <NUM>. <NUM>), whereby the UE can establish a Protocol Data Unit (PDU) session while being in a certain area defined by the LADN.

There currently exist certain challenge(s). An LADN provides access to a DN via a PDU session, but is only available in a specific LADN service area. Accordingly, usage of LADN requires that UEs seeking access to the DN are configured to setup a PDU session for a given LADN, and that the network is configured with LADN service areas.

The document <CIT> describes session management method, device and system. The document <CIT> describes network element selection method and device.

Using Data Network Access Identifier (DNAI) to identify a Session Management Function (SMF) supporting connection to a local Data Network (DN) is provided. In cases where a currently serving SMF does not support connection to a local DN, solutions proposed herein insert an Intermediate SMF (I-SMF) which supports connection to the local DN. An Access and Mobility Function (AMF) can identify the I-SMF to be inserted using DNAI.

There are, proposed herein, various embodiments which address one or more of the issues disclosed herein. In some embodiments, a method performed by an SMF for providing access to a DN is provided. The method comprises registering a Network Function (NF) profile for the SMF, the NF profile including a first DNAI that indicates that the SMF has access to a DN identified by the first DNAI.

In some embodiments, the first DNAI indicates that the SMF supports a User Plane Function (UPF) that supports access to the DN.

In some embodiments, the method further comprises receiving, from an AMF a message indicating selection of a second SMF using the first DNAI.

In some embodiments, the method further comprises receiving, from an AMF, a message that causes insertion of the SMF for an existing Protocol Data Unit (PDU) session, the message comprising the first DNAI. In some embodiments, the method further comprises selecting a UPF using the first DNAI. In some embodiments, the method further comprises performing one or more actions such that the SMF and the selected UPF are inserted for the existing PDU session. In some embodiments, performing the one or more actions comprises retrieving a Session Management (SM) context for the existing PDU Session from a second SMF controlling the PDU session. In some embodiments, performing the one or more actions further comprises receiving the SM context from the second SMF controlling the PDU session. In some embodiments, the existing PDU session is associated with a second DNAI that identifies a second DN.

In some embodiments, the DN is a local DN.

In some embodiments, a method performed by an SMF for supporting connection to a DN is provided. The method comprises obtaining a Policy Control Function (PCF) rule to use a DN identified by a first DNAI for some or all traffic when a User Equipment (UE) is in an area of interest. The method further comprises receiving a notification that a particular UE having an existing PDU session is in the area of interest. Upon receiving the notification that the particular UE is in the area of interest, the method further comprises notifying an AMF that the SMF does not support the first DNAI, thereby triggering insertion of an I-SMF that supports access to the first DNAI into the existing PDU session of the UE.

In some embodiments, the method further comprises determining that the SMF does not support the first DNAI.

In some embodiments, the method further comprises obtaining information that the particular UE is subject to the PCF rule.

In some embodiments, the method further comprises subscribing to event reporting from the AMF for the area of interest for the particular UE, wherein receiving the notification that the particular UE is in the area of interest comprises receiving the notification responsive to subscribing to event reporting from the AMF for the area of interest for the particular UE.

In some embodiments, the SMF is an SMF of a Fifth Generation Core (5GC).

In some embodiments, a method performed by an AMF for identifying an SMF with access to a DN is provided. The method comprises receiving a notification from a first SMF controlling a PDU session of a UE that the first SMF does not support a DNAI desired for the PDU session. The method further comprises discovering a second SMF supporting the DNAI.

In some embodiments, the method further comprises notifying the first SMF controlling the PDU session of the UE that the UE is in an area of interest in which a DN identified by the DNAI is to be used for some or all traffic of the UE.

In some embodiments, discovering the second SMF supporting the DNAI comprises querying a Network Function Repository Function (NRF) for an SMF that supports the DNAI.

In some embodiments, the method further comprises selecting the second SMF supporting the DNAI as an I-SMF for the PDU session. In some embodiments, the method further comprises, in response to selecting the I-SMF, requesting a SM context for the PDU session.

In some embodiments, the AMF is an AMF of a 5GC.

In some embodiments, a network node in a communications system is provided. The network node is configured to perform the method of any of the above embodiments. In some embodiments, the network node further comprises a communication interface and processing circuitry configured to perform the method of any of the above embodiments.

Certain embodiments may provide a technical advantage, whereby an SMF requires less configuration while facilitating access to DNs.

Core Network Node: As used herein, a "core network node" is any type of node in a core network or any node that implements a core network function. Some examples of a core network node include, e.g., a Mobility Management Entity (MME), a Packet Data Network Gateway (P-GW), a Service Capability Exposure Function (SCEF), a Home Subscriber Server (HSS), or the like. Some other examples of a core network node include a node implementing a Access and Mobility Function (AMF), a User Plane Function (UPF), a Session Management Function (SMF), an Authentication Server Function (AUSF), a Network Slice Selection Function (NSSF), a Network Exposure Function (NEF), a Network Function (NF) Repository Function (NRF), a Policy Control Function (PCF), a Unified Data Management (UDM), or the like.

<FIG> illustrates one example of a cellular communications system <NUM> in which embodiments of the present disclosure may be implemented. In the embodiments described herein, the cellular communications system <NUM> is a <NUM> System (5GS) including a NR RAN or LTE RAN (i.e., E-UTRA RAN). In this example, the RAN includes base stations <NUM>-<NUM> and <NUM>-<NUM>, which in <NUM> NR are referred to as gNBs (e.g., LTE RAN nodes connected to 5GC, which are referred to as gn-eNBs), controlling corresponding (macro) cells <NUM>-<NUM> and <NUM>-<NUM>. The base stations <NUM>-<NUM> and <NUM>-<NUM> are generally referred to herein collectively as base stations <NUM> and individually as base station <NUM>. Likewise, the (macro) cells <NUM>-<NUM> and <NUM>-<NUM> are generally referred to herein collectively as (macro) cells <NUM> and individually as (macro) cell <NUM>. The RAN may also include a number of low power nodes <NUM>-<NUM> through <NUM>-<NUM> controlling corresponding small cells <NUM>-<NUM> through <NUM>-<NUM>. The low power nodes <NUM>-<NUM> through <NUM>-<NUM> can be small base stations (such as pico or femto base stations) or Remote Radio Heads (RRHs), or the like. Notably, while not illustrated, one or more of the small cells <NUM>-<NUM> through <NUM>-<NUM> may alternatively be provided by the base stations <NUM>. The low power nodes <NUM>-<NUM> through <NUM>-<NUM> are generally referred to herein collectively as low power nodes <NUM> and individually as low power node <NUM>. Likewise, the small cells <NUM>-<NUM> through <NUM>-<NUM> are generally referred to herein collectively as small cells <NUM> and individually as small cell <NUM>. The cellular communications system <NUM> also includes a core network <NUM>, which in the 5GS is referred to as the <NUM> Core (5GC). The base stations <NUM> (and optionally the low power nodes <NUM>) are connected to the core network <NUM>.

<FIG> illustrates a core network <NUM> represented as a <NUM> network architecture composed of core Network Functions (NFs), where interaction between any two NFs is represented by a point-to-point reference point/interface. <FIG> can be viewed as one particular implementation of the system <NUM> of <FIG>.

Seen from the access side the <NUM> network architecture shown in <FIG> comprises a plurality of UEs connected to either a RAN or an Access Network (AN) as well as an AMF. Typically, the (R)AN comprises base stations, e.g., such as eNBs or gNBs or similar. Seen from the core network side, the 5GC NFs shown in <FIG> include a NSSF, an AUSF, a UDM, an AMF, a SMF, a PCF, and an Application Function (AF).

Reference point representations of the <NUM> network architecture are used to develop detailed call flows in the normative standardization. The N1 reference point is defined to carry signaling between the UE and AMF. The reference points for connecting between the (R)AN and AMF and between the (R)AN and UPF are defined as N2 and N3, respectively. There is a reference point, N11, between the AMF and SMF, which implies that the SMF is at least partly controlled by the AMF. N4 is used by the SMF and UPF so that the UPF can be set using the control signal generated by the SMF, and the UPF can report its state to the SMF. N9 is the reference point for the connection between different UPFs, and N14 is the reference point connecting between different AMFs, respectively. N15 and N7 are defined since the PCF applies policy to the AMF and SMF, respectively. N12 is required for the AMF to perform authentication of the UE. N8 and N10 are defined because the subscription data of the UE is required for the AMF and SMF.

The 5GC network aims at separating user plane and control plane. The user plane carries user traffic while the control plane carries signaling in the network. In <FIG>, the UPF is in the user plane and all other NFs, i.e., the AMF, SMF, PCF, AF, AUSF, and UDM, are in the control plane. Separating the user and control planes guarantees each plane resource to be scaled independently. It also allows UPFs to be deployed separately from control plane functions in a distributed fashion. In this architecture, UPFs may be deployed very close to UEs to shorten the Round Trip Time (RTT) between UEs and a Data Network (DN) for some applications requiring low latency.

The 5GC network architecture is composed of modularized functions. For example, the AMF and SMF are independent functions in the control plane. Separated AMF and SMF allow independent evolution and scaling. Other control plane functions like the PCF and AUSF can be separated as shown in <FIG>. Modularized function design enables the 5GC network to support various services flexibly.

<FIG> illustrates a <NUM> network architecture using service-based interfaces between the NFs in the control plane, instead of the point-to-point reference points/interfaces used in the <NUM> network architecture of <FIG>. However, the NFs described above with reference to <FIG> correspond to the NFs shown in <FIG>. The service(s) etc. that a NF provides to other authorized NFs can be exposed to the authorized NFs through the service-based interface. In <FIG> the service-based interfaces are indicated by the letter "N" followed by the name of the NF, e.g., Namf for the service based interface of the AMF and Nsmf for the service based interface of the SMF etc. The Network Exposure Function (NEF) and the Network Function (NF) Repository Function (NRF) in <FIG> are not shown in <FIG> discussed above. However, it should be clarified that all NFs depicted in <FIG> can interact with the NEF and the NRF of <FIG> as necessary, though not explicitly indicated in <FIG>.

Some properties of the NFs shown in <FIG> and <FIG> may be described in the following manner. The AMF provides UE-based authentication, authorization, mobility management, etc. A UE even using multiple access technologies is basically connected to a single AMF because the AMF is independent of the access technologies. The SMF is responsible for session management and allocates Internet Protocol (IP) addresses to UEs. It also selects and controls the UPF for data transfer. If a UE has multiple sessions, different SMFs may be allocated to each session to manage them individually and possibly provide different functionalities per session. The AF provides information on the packet flow to the PCF responsible for policy control in order to support Quality of Service (QoS). Based on the information, the PCF determines policies about mobility and session management to make the AMF and SMF operate properly. The AUSF supports authentication function for UEs or similar and thus stores data for authentication of UEs or similar while the UDM stores subscription data of the UE. The DN, not part of the 5GC network, provides Internet access or operator services and similar.

Embodiments described herein use a Data Network Access Identifier (DNAI) to identify a SMF supporting connection to a local DN. In cases where a currently serving SMF does not support connection to a local DN, solutions proposed herein insert an Intermediate SMF (I-SMF) which supports connection to the local DN. An AMF can identify the I-SMF to be inserted using DNAI.

In this regard, a NF (e.g., SMF, AMF) in a 5GC registers its NF metadata to a NRF. The NF metadata is stored in a NF profile of the NF. This allows other NFs to discover a given NF. Embodiments described herein add a new data element in the NF profile of the SMF. This new data element is a DNAI (or list of DNAIs) supported by the SMF. A DNAI names certain access (e.g., interfaces) supported by a UPF. If a UPF supports registration of itself, it can register its supported DNAIs. However, in this case, this information is also added to the NF profile for the SMF. Thus, when an SMF sees that a local connection to a DN is needed, but it does not itself have access to the DNAI associated with the local DN, the SMF triggers the AMF to insert an I-SMF by sending the DNAI to the AMF. The AMF can then discover and select an I-SMF supporting the DNAI.

<FIG> illustrate using a DNAI to identify a SMF supporting connection to a local DN and inserting the identified SMF as an I-SMF. The procedure for inserting the I-SMF (and an Intermediate UPF (I-UPF)) supporting access to the local DN is illustrated further below with respect to <FIG>.

<FIG> is a schematic diagram of an example of the core network <NUM> of <FIG> in which a UE is connected to a first DN (DN1) over a Protocol Data Unit (PDU) session. In an exemplary aspect, the SMF registers its NF metadata to the NRF, which is stored in an NF profile of the SMF. Embodiments described herein add the DNAI(s) supported by the SMF to the NF profile of the SMF. This DNAI(s) indicates the DN access supported by the UPF controlled by the SMF (e.g., even where the UPF is self-registering). Accordingly, the other NFs in the 5GC can see, via the NF profile of the SMF, which DNAIs the SMF can access (e.g., via the UPF controlled by the SMF).

In the illustrated embodiment, the UE enters a certain area which triggers the network to connect to a local DN (which may be a local instance of DN1) by means of an Uplink Classifier (UL CL). The SMF controlling the PDU session sees that it does not have access to the UPF identified by the DNAI that has access to the local DN, and, as such, the SMF triggers insertion of an I-SMF that controls the UPF supporting the wanted DNAI.

<FIG> is a schematic diagram of the core network <NUM> of <FIG>, illustrating insertion of an I-SMF and I-UPF supporting access to the local DN according to embodiments disclosed herein. The insertion of the I-SMF can also be done at PDU session establishment, i.e., regardless of where the UE is. The insertion of the UL CL can be done at PDU session establishment or mid-session (e.g., when a UE enters a certain area).

<FIG> is a schematic diagram of an example of the core network <NUM> of <FIG> in which the UE in a first region is connected to DN1 in a second region over a PDU session via a first I-SMF (I-SMF1)/first I-UPF (I-UPF1). <FIG> is a schematic diagram of the core network <NUM> of <FIG>, illustrating replacement of I-SMF1/I-UPF1 with a second I-SMF (I-SMF2)/second I-UPF (I-UPF2) supporting access to the local DN according to embodiments disclosed herein.

<FIG> is a schematic diagram of an example of the core network <NUM> of <FIG> in which the UE in a first region is connected to DN1 in a second region over a PDU session via I-SMF1/I-UPF1.

<FIG> is a flow diagram illustrating identifying and inserting an I-SMF which supports access to a desired DN (e.g., local DN1) according to embodiments disclosed herein. At step <NUM>, the I-SMF (e.g., new I-SMF) registers its NF profile, which includes DNAI(s) via Nnrf_NFManagement_NFRegister request and response. At step <NUM>, the SMF has obtained a PCF rule that, when a UE is in a certain area (e.g., an area of interest), a specific DNAI is to be used for some or all traffic (e.g., if a UE is in the certain area, UL-CL is inserted and a local PDU Session Anchor (PSA)). At step <NUM>, the SMF has by some means obtained information that a particular UE is subject to the PCF rule (e.g., needs access to the local PSA) using UL CL if in the area of interest.

At step <NUM>, the SMF subscribes to event reporting from the AMF for the UE's presence in the area of interest via Namf_EvenExposure_Subscribe request and response. At step <NUM>, the AMF notifies the SMF of the UE's presence in the area of interest via Namf_EventExposure_Notify. At step <NUM>, the SMF sees that it does not support the DNAI to be used for some or all traffic when the UE is in the area of interest (i.e., the SMF sees that it does not have access to the UPF identified by the DNAI that has access to the local DN), and the SMF sends a NSmf_PDUSession_SMContextStatusNotify to the AMF, where the NSmf_PDUSession_SMContextStatusNotify is updated to also include a notification to the AMF that an I-SMF supporting a specific DNAI is to be included (i.e., inserted).

At step <NUM>, the AMF discovers the new I-SMF using the DNAI as one of the query parameters sent to the NRF via Nnrf_NFDiscovery request and receiving the respective response. At step <NUM>, the AMF selects the new I-SMF, which has access to the local DN for the PDU session. The AMF then initiates a procedure for inserting the new I-SMF into the existing PDU session. More specifically, in this example at step <NUM>, the AMF requests a Session Management (SM) context using the DNAI from the new I-SMF via Nsmf_PDUSession_CreateSMContext Request. In the case of an I-SMF change (e.g., as illustrated in <FIG>), the request includes an SM Context Identifier (ID) which points to the old I-SMF.

At step <NUM>, the new I-SMF retrieves the SM Context from the old I-SMF (in cases of I-SMF change) or SMF (in cases of I-SMF insertion) using the DNAI by invoking Nsmf_PDUSession_Context Request (SM context type, SM Context ID). The SM Context ID is used by the recipient of Nsmf_PDUSession_Context Request in order to determine the targeted PDU Session. At step <NUM>, the SMF/old I-SMF responds with the SM context of the indicated PDU Session.

At step <NUM>, the new I-SMF selects a new I-UPF based on the DNAI. That is, the new I-SMF selects a new I-UPF which has access to the local DN, indicated by the DNAI. The new I-SMF then performs actions such that the SMF and the selected UPF are inserted for the existing PDU session. More specifically, in this example at step <NUM>, the new I-SMF initiates a N4 Session Establishment to the new I-UPF.

At step <NUM>, steps <NUM>-<NUM> and <NUM>-<NUM> of clause <NUM>. <NUM> in 3GPP Technical Specification (TS) <NUM> are performed (e.g., inserting the new I-SMF as an I-SMF for the PDU Session). At step <NUM>, steps <NUM>-<NUM> of clause <NUM>. <NUM> in 3GPP TS <NUM> are performed.

At step <NUM>, the SMF subscribes to event reporting from the AMF for the UE's presence in the area of interest via Namf_EvenExposure_Subscribe request and response. At step <NUM>, the AMF notifies the SMF that the UE is out of the area of interest via Namf_EventExposure_Notify. At step <NUM>, the SMF releases the new I-SMF via NSmf_PDUSession_SMContextStatusNotify. At step <NUM>, steps <NUM>-<NUM> of clause <NUM>. <NUM> in 3GPP TS <NUM> are performed.

It should be understood that the steps described with respect to <FIG> can be modified as needed for particular scenarios, such as those illustrated in <FIG>. For example, in the scenario of <FIG>, the old I-SMF (I-SMF1) and I-UPF (I-UPF1) can be removed with the insertion of the new I-SMF (I-SMF2) and new I-UPF (I-UPF2), such as described further in 3GPP TS <NUM> clause <NUM>.

<FIG> is a schematic block diagram of a network node <NUM> according to some embodiments of the present disclosure. Optional features are represented by dashed boxes. The network node <NUM> may be, for example, a core network node (e.g., a MME), a network node that implements a core network function (e.g., an AMF), or a radio access node (e.g., the base station <NUM> or <NUM>) that implements all or part of the functionality of a network node (e.g., a base station, an AMF, an SMF, etc.) described herein. As illustrated, the network node <NUM> includes a control system <NUM> that includes one or more processors <NUM> (e.g., Central Processing Units (CPUs), Application Specific Integrated Circuits (ASICs), Field Programmable Gate Arrays (FPGAs), and/or the like), memory <NUM>, and a network interface <NUM>. The one or more processors <NUM> are also referred to herein as processing circuitry. In addition, if the network node <NUM> is a radio access node, the network node <NUM> may include one or more radio units <NUM> that each includes one or more transmitters <NUM> and one or more receivers <NUM> coupled to one or more antennas <NUM>. The radio units <NUM> may be referred to or be part of radio interface circuitry. In some embodiments, the radio unit(s) <NUM> is external to the control system <NUM> and connected to the control system <NUM> via, e.g., a wired connection (e.g., an optical cable). However, in some other embodiments, the radio unit(s) <NUM> and potentially the antenna(s) <NUM> are integrated together with the control system <NUM>. The one or more processors <NUM> operate to provide one or more functions of a network node <NUM> as described herein (e.g., one or more functions of a base station, a MME, an AMF, an SMF, etc. described herein, e.g., with respect to <FIG>). In some embodiments, the function(s) are implemented in software that is stored, e.g., in the memory <NUM> and executed by the one or more processors <NUM>.

<FIG> is a schematic block diagram that illustrates a virtualized embodiment of the network node <NUM> according to some embodiments of the present disclosure. As used herein, a "virtualized" network node is an implementation of the network node <NUM> in which at least a portion of the functionality of the network node <NUM> is implemented as a virtual component(s) (e.g., via a virtual machine(s) executing on a physical processing node(s) in a network(s)). As illustrated, in this example, the radio access node <NUM> includes one or more processing nodes <NUM> coupled to or included as part of a network(s) <NUM>. Each processing node <NUM> includes one or more processors <NUM> (e.g., CPUs, ASICs, FPGAs, and/or the like), memory <NUM>, and a network interface <NUM>. If the network node <NUM> is a radio access node, the network node <NUM> may also include the control system <NUM> and/or the one or more radio units <NUM>, as described above. The control system <NUM> may be connected to the radio unit(s) <NUM> via, for example, an optical cable or the like. If present, the control system <NUM> or the radio unit(s) <NUM> are connected to the processing node(s) <NUM> via the network <NUM>.

In this example, functions <NUM> of the network node <NUM> described herein (e.g., one or more functions of a base station, an AMF, an SMF, etc. described herein, e.g., with respect to <FIG>) are implemented at the one or more processing nodes <NUM> or distributed across the one or more processing nodes <NUM> and the control system <NUM> and/or the radio unit(s) <NUM> in any desired manner. In some particular embodiments, some or all of the functions <NUM> of the network node <NUM> described herein are implemented as virtual components executed by one or more virtual machines implemented in a virtual environment(s) hosted by the processing node(s) <NUM>. As will be appreciated by one of ordinary skill in the art, additional signaling or communication between the processing node(s) <NUM> and the control system <NUM> is used in order to carry out at least some of the desired functions <NUM>. Notably, in some embodiments, the control system <NUM> may not be included, in which case the radio unit(s) <NUM> communicate directly with the processing node(s) <NUM> via an appropriate network interface(s).

In some embodiments, a computer program including instructions which, when executed by at least one processor, causes the at least one processor to carry out the functionality of network node <NUM> or a node (e.g., a processing node <NUM>) implementing one or more of the functions <NUM> of the network node <NUM> in a virtual environment according to any of the embodiments described herein is provided.

<FIG> is a schematic block diagram of the network node <NUM> according to some other embodiments of the present disclosure. The network node <NUM> includes one or more modules <NUM>, each of which is implemented in software. The module(s) <NUM> provide the functionality of the network node <NUM> described herein (e.g., one or more functions of a base station, an AMF, an SMF, etc. described herein, e.g., with respect to <FIG>).

Claim 1:
A method performed by a Session Management Function, SMF, for providing access to a Data Network, DN, the method comprising:
- registering (<NUM>) a Network Function, NF, profile for the SMF, the NF profile including a first DN Access Identifier, DNAI, that indicates that the SMF has access to a DN identified by the first DNAI.