Patent Description:
In the Third Generation Partnership Project (3GPP) Fifth Generation (<NUM>) core (5GC), a User Equipment (UE) may have multiple General Public Subscription Identifiers (GPSIs) associated to the same Subscription Permanent Identifier (SUPI).

As specified in 3GPP Technical Specification (TS) <NUM> V16.

As specified in 3GPP TS <NUM> V15.

The UE may acquire the following configuration information from the Session Management Function (SMF) during the lifetime of a Protocol Data Unit (PDU) Session:.

Related technology is disclosed in the 3GPP document<NPL>). This document discloses a AMF that decides whether a POU Session can be handed over between 3GPP and non-3GPP accesses. If a UE is registered to the different PLMNs via 3GPP and non-3GPP access, only a Home Routed POU Sessions can be handed over to the other access. If a UE is registered to the same PLMN via 3GPP and non-3GPP access, a POU Session can be handed over to the other access regardless of roaming mode of the POU Session. Another related technology is disclosed in the 3GPP document<NPL>). This document discloses a Selection Mode that indicates whether a subscribed APN was selected, or a non-subscribed APN sent by the UE was selected. The P-GW may use Selection Mode when deciding whether to accept or reject the [UE request]. Similar information is needed when the AMF has selected a SMF for a DNN that is not explicitly listed in the UE subscription.

There currently exist certain challenge(s). The Access and Mobility Management Function (AMF) only knows, for a given SUPI for a UE, a list of GPSI(s). This is insufficient, e.g., to support Lawful Interception (LI), as specified in 3GPP TS <NUM> V15. <NUM>, subclause <NUM>. <NUM>, as below:.

In the case when a UE has multiple GPSIs, a PDU session activated by UE may be linked to only one of GPSI. This means that only the signaling and/or user plane traffic applicable to this GPSI, i.e. the PDU session linked to this GPSI, shall be intercepted, but NOT others.

The AMF is to know, for a given PDU session(s) from a UE (identified by a SUPI), which GPSI is associated with which PDU session(s).

Certain embodiments may provide one or more of the following technical advantage(s). The disclosure enables the AMF to know the exact GPSI, among a list of GPSIs for a UE (identified by a SUPI), to be associated with a PDU session.

Additional information may also be found in the document(s) provided in the Appendix.

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 (PGW), 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 Repository Function (NRF), a Policy Control Function (PCF), a Unified Data Management (UDM), or the like.

<FIG> illustrates one example of a cellular communications network <NUM>-<NUM> according to some embodiments of the present disclosure. In the embodiments described herein, the cellular communications network <NUM>-<NUM> is a <NUM> NR network. In this example, the cellular communications network <NUM>-<NUM> includes base stations <NUM>-<NUM> and <NUM>-<NUM>, which in LTE are referred to as eNBs and in <NUM> NR are referred to as gNBs, 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 cellular communications network <NUM>-<NUM> 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 base stations <NUM> (and optionally the low power nodes <NUM>) are connected to a core network <NUM>-<NUM>.

<FIG> illustrates a wireless communication system represented as an exemplifying Evolved Packet System (EPS) architecture comprising a RAN in the form of an Evolved Universal Terrestrial Radio Access Network (E-UTRAN) and a core network in the form of a Evolved Packet Core (EPC). The EPC comprises core network nodes such as the Mobility Management Entity (MME), Home Subscriber Server (HSS), Serving Gateway (SGW), PDN Gateway (PGW) and Policy and Charging Rules Function (PCRF).

<FIG> illustrates a wireless communication system <NUM>-<NUM> represented as a <NUM> System 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>-<NUM> of <FIG>.

Seen from the access side the <NUM> network architecture shown in <FIG> comprises a plurality of User Equipment (UEs) connected to either a Radio Access Network (RAN) or an Access Network (AN) as well as an Access and Mobility Management Function (AMF). Typically, the R(AN) comprises base stations, e.g. such as evolved Node Bs (eNBs) or <NUM> base stations (gNBs) or similar. Seen from the core network side, the <NUM> core NFs shown in <FIG> include a Network Slice Selection Function (NSSF), an Authentication Server Function (AUSF), a Unified Data Management (UDM), an AMF, a Session Management Function (SMF), a Policy Control Function (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 AN and AMF and between the 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 SMP, 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 <NUM> core 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 data network for some applications requiring low latency.

The core <NUM> 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 <NUM> core network to support various services flexibly.

<FIG> illustrates a <NUM> System architecture <NUM>-<NUM> using service-based interfaces between the NFs in the control plane, instead of the point-to-point reference points/interfaces used in the <NUM> System 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 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 Data Network (DN), not part of the <NUM> core network, provides Internet access or operator services and similar.

<FIG> illustrates the operation of a NF service producer <NUM>-<NUM> (e.g., a SMF or H-SMF) and a NF service consumer (i.e., a NF that consumes a service of the NF service producer) in accordance with some embodiment of the present disclosure. In the preferred embodiments described herein, the NF service producer is either a SMF or a H-SMF. As illustrated, the NF service consumer sends a request to the NF service producer, where the request is associated with a PDU session (e.g., is a request to create a SM context for the PDU session or a request to create the PDU session) (step WT300). The NF service producer sends a response to the NF service consumer, where the response includes a GPSI of the PDU session (step WT302). As discussed below, in some embodiments, there are some conditions under which the response WT302 may include a GPSI of the PDU session (i.e., a GPSI mapped to or otherwise linked to the PDU session) and some other conditions under which the response in WT302 may not include a GPSI of the PDU session.

<FIG> provide two example implementations of the process of <FIG>.

<FIG> illustrates a procedure for creating a SM context for a PDU session in which the SMF provides the GPSI of the PDU session to the NF service consumer. In General, the Create SM Context service operation is used to create an individual SM context, for a given PDU session, in the SMF, or in the V-SMF for HR roaming scenarios. The Create SM Context service is used in the following procedures:.

There shall be only one individual SM context per PDU session.

<FIG> described in greater detail here discloses a method to create an SM context by using the HTTP POST method. The steps of <FIG> are as follows:.

Step XX100: The NF Service Consumer shall send a POST request to the resource representing the SM contexts collection resource of the SMF. The payload body of the POST request shall contain:.

For the UE requested PDU Session Establishment procedure in home routed roaming scenario (see subclause <NUM>. <NUM> of 3GPP TS <NUM> [<NUM>]), the NF Service Consumer shall provide the URI of the Nsmf_PDUSession service of the H-SMF in the hSmfUri IE and may provide the URI of the Nsmf_PDUSession service of additional H-SMFs. The V-SMF shall try to create the PDU session using the hSmfUri IE. If due to communication failure on the N16 interface the V-SMF does not receive any response from the H-SMF, then:.

The payload body of the POST request may further contain:.

Step XX102A: On success, "<NUM> Created" shall be returned, the payload body of the POST response shall contain the representation describing the status of the request and the "Location" header shall be present and shall contain the URI of the created resource. The authority and/or deployment-specific string of the apiRoot of the created resource URI may differ from the authority and/or deployment-specific string of the apiRoot of the request URI received in the POST request.

If the Request Type was received in the request and set to EXISTING_PDU_SESSION or EXISTING_EMERGENCY_PDU SESSION (e.g. indicating that this is a request for an existing PDU session or an existing emergency PDU session), the SMF shall identify the existing PDU session or emergency PDU session based on the PDU Session ID; in this case, the SMF shall not create a new SM context but instead update the existing SM context and provide the representation of the updated SM context in the "<NUM> Created" response to the NF Service Consumer.

The POST request shall be considered as colliding with an existing SM context if:.

A POST request that collides with an existing SM context shall be treated as a request for a new SM context. Before creating the new SM context, the SMF should delete the existing SM context locally and any associated resources in the UPF and PCF. If the smContextStatusUri of the existing SM context differs from the smContextStatusUri received in the POST request, the SMF shall also send an SM context status notification (see subclause <NUM>. <NUM>) targeting the smContextStatusUri of the existing SM context to notify the release of the existing SM context. For a HR PDU session, if the H-SMF URI in the request is different from the H-SMF URI of the existing PDU session, the V-SMF should also delete the existing PDU session in the H-SMF by invoking the Release service operation (see subclause <NUM>.

If the Request Type was received in the request and indicates this is a request for a new PDU session (i.e. INITIAL_REQUEST) and if the Old PDU Session ID was also included in the request, the SMF shall identify the existing PDU session to release and to which the new PDU session establishment relates, based on the Old PDU Session ID.

For an existing PDU session, e.g. PDU session moved from another access or another system, if a GPSI is associated with the PDU session, the SMF shall include the associated GPSI in the response body; For an existing HR PDU session, if the GPSI associated with the PDU session is received from H-SMF in PDU Session Create response, the SMF shall include it in the response body.

Step XX102B: If the request does not include the "UE presence in LADN service area" indication and the SMF determines that the DNN corresponds to a LADN, then the SMF shall consider that the UE is outside of the LADN service area. The SMF shall reject the request if the UE is outside of the LADN service area.

On failure, or redirection during a UE requested PDU Session Establishment, one of the HTTP status code listed in Table <NUM>. <NUM>-<NUM> shall be returned. For a 4xx/5xx response, the message body shall contain an SmContextCreateError structure, including:.

<FIG> illustrates a procedure for creating a PDU session in which the H-SMF provides the GPSI of the PDU session to the NF service consumer. In general, the Create service operation shall be used to create an individual PDU session in the H-SMF for HR roaming scenarios. The Create service operation is used in the following procedures:.

<FIG> described in greater detail here discloses a method for the NF service consumer (e.g. V-SMF) to create a PDU session by using the HTTP POST method. As illustrated, the steps of <FIG> are as follows.

Step XX200: The NF Service Consumer shall send a POST request to the resource representing the PDU sessions collection resource of the H-SMF. The payload body of the POST request shall contain:.

As specified in subclause <NUM>. <NUM> of 3GPP TS <NUM> [<NUM>], the NF Service Consumer shall be able to receive an Update request before receiving the Create Response, e.g. for EPS bearer ID allocation (see subclause <NUM>. <NUM> of 3GPP TS <NUM> [<NUM>]) or Secondary authorization/authentication (see subclause <NUM>. <NUM> of 3GPP TS <NUM> [<NUM>]).

Step XX202A: On success, "<NUM> Created" shall be returned, the payload body of the POST response shall contain:.

The authority and/or deployment-specific string of the apiRoot of the created resource URI may differ from the authority and/or deployment-specific string of the apiRoot of the request URI received in the POST request.

If an Update Request was sent to the V-SMF before the Create Response, the URI in the "Location" header and in the hsmfPduSessionUri IE of the H-SMF initiated Update Request shall be the same. If the Request Type was received in the request and set to EXISTING_PDU_SESSION or EXISTING_EMERGENCY_PDU SESSION (e.g. indicating that this is a request for an existing PDU session or an existing emergency PDU session), the SMF shall identify the existing PDU session or emergency PDU session based on the PDU Session ID; in this case, the SMF shall not create a new PDU session or emergency PDU session but instead update the existing PDU session or emergency PDU session and provide the representation of the updated PDU session or emergency PDU session in the response to the NF Service Consumer.

The POST request shall be considered as colliding with an existing PDU session context if:.

A POST request that collides with an existing PDU session context shall be treated as a request for a new PDU session context. Before creating the new PDU session context, the SMF should delete the existing PDU session context locally and any associated resources in the UPF and PCF. If the vsmfPduSessionUri of the existing PDU session context differs from the vsmfPduSessionUri received in the POST request, the SMF shall also send a status notification (see subclause <NUM>. <NUM>) targeting the vsmfPduSessionUri of the existing PDU session context to notify the release of the existing PDU session context.

If the Request Type was received in the request and indicates this is a request for a new PDU session (i.e. INITIAL_REQUEST) and if the Old PDU Session ID was also included in the request, the SMF shall identify the existing PDU session to be released and to which the new PDU session establishment relates, based on the Old PDU Session ID.

The NF Service Consumer shall store any epsPdnCnxlnfo and EPS bearer information received from the H-SMF.

If the response received from the H-SMF contains the alwaysOnGranted attribute set to true, the V-SMF shall check and determine whether the PDU session can be established as an always-on PDU session based on local policy.

For existing PDU session, e.g. PDU session moved from another access or another system, if a GPSI is associated with the PDU session, the SMF shall included it in the response body.

Step XX202B: On failure, or redirection during a UE requested PDU Session Establishment, one of the HTTP status code listed in Table <NUM>. <NUM>-<NUM> shall be returned. For a 4xx/5xx response, the message body shall contain a PduSessionCreateError structure, including:.

Additional information is found in the document(s) provided in the Appendix. The information provided includes an additional description of the GPSI for context of the present disclosure.

<FIG> is a schematic block diagram of a network node QQ200 according to some embodiments of the present disclosure. The network node QQ200 may be, for example, a NF in the core network QQ110-<NUM> or a network node implementing a NF in the core network QQ110. As illustrated, the network node QQ200 includes one or more processors QQ204 (e.g., Central Processing Units (CPUs), Application Specific Integrated Circuits (ASICs), Field Programmable Gate Arrays (FPGAs), and/or the like), memory QQ206, and a network interface QQ208. The one or more processors QQ204 are also referred to herein as processing circuitry. The one or more processors QQ204 operate to provide one or more functions of a network node QQ200 (e.g., one or more functions of a NF service consumer QQ210 e.g. such as an AMF or a V-SMF, or a NF service producer QQ220 e.g. such as a SMF, or a H-SMF) as described herein. In some embodiments, the function(s) are implemented in software that is stored, e.g., in the memory QQ206 and executed by the one or more processors QQ204.

<FIG> is a schematic block diagram that illustrates a virtualized embodiment of the network node QQ200 according to some embodiments of the present disclosure. A used herein, a "virtualized" network node is an implementation of the network node QQ200 in which at least a portion of the functionality of the network node QQ200 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 network node QQ200 includes one or more processors QQ304 (e.g., CPUs, ASICs, FPGAs, and/or the like), memory QQ306, and a network interface QQ308. In this example, functions QQ310 of the network node QQ200 (e.g., one or more functions of a NF service consumer, a NF service producer, a SMF, or a H-SMF) described herein are implemented at the one or more processing nodes QQ300. In some particular embodiments, some or all of the functions QQ310 of the network node QQ200 (e.g., one or more functions of a NF service consumer, a NF service producer, a SMF, or a H-SMF) 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) QQ300.

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 the network node QQ200 or a node (e.g., a processing node QQ300) implementing one or more of the functions QQ310 of the network node QQ200 in a virtual environment according to any of the embodiments described herein is provided.

<FIG> is a schematic block diagram of the network node QQ200 according to some other embodiments of the present disclosure. The network node QQ200 includes one or more modules QQ400, each of which is implemented in software. The module(s) QQ400 provide the functionality of the network node QQ200 (e.g., one or more functions of a NF service consumer QQ210 such as e.g. an AMF or a V-SMF, or a NF service producer QQ220 such as e.g. a SMF, or a H-SMF) described herein. This discussion is equally applicable to the processing node QQ300 of Figure QQ3 where the modules QQ400 may be implemented at one of the processing nodes QQ300 or distributed across multiple processing nodes QQ300 and/or distributed across the processing node(s) QQ300 and the control system QQ202.

Claim 1:
A method by an Access and Mobility Management Function, AMF, node, (<NUM>-<NUM>) acting as a network function, NF, consumer operative in a Fifth Generation System, 5GS, (<NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM>) that comprises a User Equipment, UE, (<NUM>) associated with a Subscriber Permanent Identifier, SUPI, that is associated with subscription data of the UE, the method comprises:
- sending (WT300, XX100, XX200) towards a Session Management Function, SMF, node (<NUM>-<NUM>) acting as a NF service producer, a request relating to a Protocol Data Unit, PDU, Session of the UE and comprising a Request Type that is set to Existing PDU Session; and
- receiving (WT302, XX102A, XX202A), from the SMF node, a response comprising a Generic Public Subscription Identifier, GPSI, associated with the PDU session of the UE, which UE is associated with the SUPI and which GPSI is an external identifier to be used in networks outside the 5GS for addressing the subscription data of the UE.