Enhancement of operator determined barring

Abstract

Systems and methods are disclosed that relate to Operator Determined Barring (ODB) in a cellular communications system. In one embodiment, a method comprises, at an Access and Mobility Management Function (AMF), receiving a request to establish a Protocol Data Unit (PDU) session for a User Equipment (UE), determining that establishment of the PDU session is to be rejected, and sending, to a Session Management Function (SMF), a request comprising an indication to reject establishment of the PDU session. The method further comprises, at the SMF, receiving, from the AMF, the request comprising the indication to reject establishment of the PDU session and, responsive to receiving the request, sending, to the AMF, a failure response to reject the request to establish the PDU session for the UE. Embodiments of an AMF and an SMF are also disclosed as well as embodiments of methods of operation thereof.

Description

ENHANCEMENT OF OPERA TOR DETERMINED BARRINGRelated Applications

[0001] This application claims the benefit of international application serial number PCT / CN2023 / 122560, filed September 28, 2023, the disclosure of which is hereby incorporated herein by reference in its entirety.Technical Field

[0002] The present disclosure relates to a cellular communications system and, more specifically, to Operator Determined Barring (ODB) of a Protocol Data Unit (PDU) session establishment.Background

[0003] The following is an excerpt from chapter 2.5B Barring of PDU Session establishment of 3rdGeneration Partnership Project (3GPP) Technical Specification (TS) 23.015 V17.0.0:2.5B.2 Invocation of BarringBarring of PDU Session establishment is invoked in the SMF. If the SMF receives from an UE connected over 5GS a PDU Session connectivity request which is prohibited by Operator Determined Barring, the SMF shall return a negative response to the request with an appropriate error indication to the UE over the 5G radio path.Barring of PDU Session establishsmentfor other barring categories for the Packet Oriented Services, SMF determines whether a request for PDU Session establishment shall be barred or not:For "bar a subscriber from requesting Packet Oriented Services from access points that are within the HPLMN whilst the subscriber is roaming in a VPLMN”, if the subscriber is not located in the HPLMN and the SMF being accessed is located in HPLMN, then the SMF shall reject the PDU connectivity request,For "bar a subscriber from requesting Packet Oriented Services from access points that are within the roamed to VPLMN”, if the subscriber is not located in the HPLMN and the SMF being accessed is located in VPLMN, then the SMF shall reject the PDU connectivity request.

[0004] Figure 1 is a message flow diagram for the handling of Operator Determined Barring of Protocol Data Unit (PDU) Session establishment. As illustrated, a UE sends a PDU Connectivity Request to a Session Management Function (SMF). In this example, 5thGeneration (5G) PDU connectivity is barred because of ODB. As such, the SMF responds with a Reject message including a cause of the rejection.Summary

[0005] Systems and methods are disclosed that relate to Operator Determined Barring (ODB) in a cellular communications system. In one embodiment, a method comprises, at an Access and Mobility Management Function (AMF), receiving a request to establish a Protocol Data Unit (PDU) session for a User Equipment (UE), determining that establishment of the PDU session is to be rejected, and sending, to a Session Management Function (SMF), a request comprising an indication to reject establishment of the PDU session. The method further comprises, at the SMF, receiving, from the AMF, the request comprising the indication to reject establishment of the PDU session and, responsive to receiving the request, sending, to the AMF, a failure response to reject the request to establish the PDU session for the UE. In this manner, resource allocation, particularly for the home-routed roaming and Intermediate SMF (I-SMF) insertion for non-roaming or Local Breakout (LBO) scenarios, can be optimized when establishment of the PDU session is rejected due to a check at the AMF.

[0006] In one embodiment, the request sent from the AMF to the SMF is a request to create a session management context associated to the PDU session requested to be established.

[0007] In one embodiment, the request sent from the AMF to the SMF further comprises information that indicates a reason to reject establishment of the PDU session. In one embodiment, the reason to reject establishment of the PDU session is ODB.

[0008] In one embodiment, the request sent from the AMF to the SMF is a Create Session Management (SM) context request comprising SmContextCreateData, wherein the SmContextCreateData comprises the indication to reject the establishment of the PDU session and information that indicates a cause of PDU establishment rejection. In one embodiment, the indicated cause of PDU establishment rejection is ODB. The SmContextCreateData may be referred to as, for example, a type of an Information Element (IE), object, or message content.

[0009] In one embodiment, the indication to reject establishment of the PDU session directly indicates that establishment of the PDU session is rejected due to ODB.

[0010] Embodiments of a method of operation of an AMF are also disclosed. In one embodiment, a method performed by an AMF of a cellular communications system comprises receiving a request to establish a PDU session for a UE, determining thatestablishment of the PDU session is to be rejected, and sending, to an SMF, a request comprising an indication to reject establishment of the PDU session.

[0011] In one embodiment, the request sent from the AMF to the SMF is a request to create a session management context associated to the PDU session requested to be established.

[0012] In one embodiment, the request sent from the AMF to the SMF further comprises information that indicates a reason to reject establishment of the PDU session. In one embodiment, the reason to reject establishment of the PDU session is ODB.

[0013] In one embodiment, the request sent from the AMF to the SMF is a Create SM context request comprising a SmContextCreateData IE, wherein the SmContextCreateData IE comprises the indication to reject the establishment of the PDU session and information that indicates a cause of PDU establishment rejection. In one embodiment, the indicated cause of PDU establishment rejection is ODB.

[0014] In one embodiment, the indication to reject establishment of the PDU session directly indicates that establishment of the PDU session is rejected due to ODB.

[0015] Corresponding embodiments of an AMF are also disclosed. In one embodiment, an AMF for a cellular communications system is adapted to receive a request to establish a PDU session for a UE, determine that establishment of the PDU session is to be rejected, and send, to an SMF, a request comprising an indication to reject establishment of the PDU session.

[0016] In one embodiment, a network node for implementing an AMF for a cellular communications system comprises a network interface and processing circuitry associated with the network interface. The processing circuitry is configured to cause the network node to receive a request to establish a PDU session for a UE, determine that establishment of the PDU session is to be rejected, and send, to an SMF, a request comprising an indication to reject establishment of the PDU session.

[0017] Embodiments of a method performed by an SMF are also disclosed. In one embodiment, a method performed by an SMF of a cellular communications system comprises receiving, from an AMF of the cellular communications system, a request comprising an indication to reject establishment of a PDU session for a UE and, responsive to receiving the request, sending, to the AMF, a failure response to reject the request to establish the PDU session for the UE.

[0018] In one embodiment, the request received from the AMF is a request to create a session management context associated to the PDU session requested to be established.

[0019] In one embodiment, the request received from the AMF further comprises information that indicates a reason to reject establishment of the PDU session. In one embodiment, the reason to reject establishment of the PDU session is ODB.

[0020] In one embodiment, the request received from the AMF is a Create SM context request comprising a SmContextCreateData IE, wherein the SmContextCreateData IE comprises the indication to reject the establishment of the PDU session and information that indicates a cause of PDU establishment rejection. In one embodiment, the indicated cause of PDU establishment rejection is ODB.

[0021] In one embodiment, the indication to reject establishment of the PDU session directly indicates that establishment of the PDU session is rejected due to ODB.

[0022] Corresponding embodiments of an SMF are also disclosed. In one embodiment, an SMF for a cellular communications system is adapted to receive, from an AMF of the cellular communications system, a request comprising an indication to reject establishment of a PDU session for a UE and, responsive to receiving the request, send, to the AMF, a failure response to reject the request to establish the PDU session for the UE.

[0023] In one embodiment, a network node for implementing an SMF for a cellular communications system comprises a network interface and processing circuitry associated with the network interface. The processing circuitry is configured to cause the network node to receive, from an AMF of the cellular communications system, a request comprising an indication to reject establishment of a PDU session for a UE and, responsive to receiving the request, send, to the AMF, a failure response to reject the request to establish the PDU session for the UE.

[0024] In another embodiment, a method performed by an AMF comprises receiving a request to establish a PDU session for a UE, determining that establishment of the PDU session is to be rejected, and sending, to the UE, a message that indicates that the request to establish the PDU session is rejected and comprises information that indicates a reason that the request to establish the PDU session is rejected.

[0025] In one embodiment, the message sent to the UE is a PDU session establishment reject message comprising the information that indicates the reason that the request to establish the PDU session is rejected.

[0026] In one embodiment, the message sent to the UE is a downlink (DL) Non- Access Stratum (NAS) transport message comprising the information that indicates the reason that the request to establish the PDU session is rejected.

[0027] In one embodiment, the reason to reject establishment of the PDU session is ODB.

[0028] In one embodiment, the request to establish the PDU session is either for home-routed PDU session establishment or PDU session establishment with I-SMF.

[0029] Corresponding embodiments of an AMF and a network node that implements an AMF are also disclosed.Brief Description of the Drawings

[0030] The accompanying drawing figures incorporated in and forming a part of this specification illustrate several aspects of the disclosure, and together with the description serve to explain the principles of the disclosure.

[0031] Figure 1 is a message flow diagram for the handling of Operator Determined Barring (ODB) of Protocol Data Unit (PDU) Session establishment;

[0032] Figure 2 illustrates barring of PDU session establishment for the scenario of home-routed roaming;

[0033] Figure 3 illustrates one example of a cellular communications system in which embodiments of the present disclosure may be implemented;

[0034] Figure 4 illustrates a wireless communication system represented as a Fifth Generation (5G) network architecture composed of core Network Functions (NFs);

[0035] Figure 5 illustrates a 5G network architecture using service-based interfaces between the NFs in the Control Plane (CP);

[0036] Figure 6 illustrates a 5G architecture for the home-routed roaming scenario;

[0037] Figure 7 illustrates a process in accordance with Alternative 1, in accordance with an example embodiment of the present disclosure;

[0038] Figure 8 illustrates a process in accordance with Alternative 2, in accordance with an example embodiment of the present disclosure;

[0039] Figure 9 is a schematic block diagram of a network node according to some embodiments of the present disclosure;

[0040] Figure 10 is a schematic block diagram that illustrates a virtualized embodiment of the network node according to some embodiments of the present disclosure; and

[0041] Figure 11 is a schematic block diagram of the network node according to some other embodiments of the present disclosure.Detailed Description

[0042] Some of the embodiments contemplated herein will now be described more fully with reference to the accompanying drawings. Other embodiments, however, are contained within the scope of the subject matter disclosed herein, the disclosed subject matter should not be construed as limited to only the embodiments set forth herein; rather, these embodiments are provided by way of example to convey the scope of the subject matter to those skilled in the art.

[0043] Note that the description given herein focuses on a 3rdGeneration Partnership Project (3GPP) cellular communications system and, as such, 3GPP terminology or terminology similar to 3GPP terminology is oftentimes used. However, the concepts disclosed herein are not limited to a 3GPP system. Definitions for some of the terminology are provided later.

[0044] Note that, in the description herein, reference may be made to the term "cell"; however, particularly with respect to 5thGeneration (5G) New Radio (NR) concepts, beams may be used instead of cells and, as such, it is important to note that the concepts described herein are equally applicable to both cells and beams.

[0045] There currently exist certain challenge(s) with existing technology. In 3GPP Technical Specification (TS) 23.015 (latest version is R17 hOO), the Operator Determined Barring (ODB) feature is described for the 5G System (5GS). The following description is the main strategy:• For subscribers completely barred from Packet Oriented Services, the Access and Mobility Management Function (AMF) may reject registration requests.• For barring of Protocol Data Unit (PDU) Session establishment for other barring categories for the Packet Oriented Services, the Session Management Function(SMF) determines whether a request for PDU Session establishment shall be barred or not.

[0046] If there is only one SMF included in the PDU Connectivity Request procedure, e.g., for non-roaming scenario or Local Break Out (LBO) without an Intermediate SMF (I-SMF), then the ODB feature as defined in 3GPP TS 23.015 should work. But for barring of PDU Session Establishment for the Home-Routed roaming scenario as shown in Figure 2, or I-SMF Insertion in the PDU Session Establishment procedure, the following problems exist when the PDU Session Establishment is barred:1. The AMF needs to additionally perform Inter-Public Land Mobile Network (PLMN) Network Function (NF) Discovery to find the Home SMF (H-SMF).2. The Visited SMF (V-SMF) needs to create a Session Management context (SMContext) and allocate the corresponding resources in Visited User Plane Function (V-UPF), Visited Charging Function (V-CHF), and other NFs, and then later release them all after receiving the failure response of Nsmf_PDUSession_Create Response if the PDU Session is barred.

[0047] Even for the non-roaming scenario or LBO case, the SMF needs to retrieve the SessionManagementSubscriptionData if this PDU Session is already known to be barred in the AMF.

[0048] Certain aspects of the present disclosure and their embodiments may provide solutions to the aforementioned or other challenges.

[0049] Figure 3 illustrates one example of a cellular communications system 300 in which embodiments of the present disclosure may be implemented. In the embodiments described herein, the cellular communications system 300 is a 5GS including a Next Generation RAN (NG-RAN) and a 5G Core (5GC); however, embodiments of the present disclosure are not limited to being used in a 5GS and may be used in other similar types of wireless communication systems such as, e.g., a 4thGeneration (4G) system (i.e., an Evolved Packet System (EPS) or Long Term Evolution (LTE) system) or a 6thGeneration (6G) system . In this example, the RAN includes base stations 302-1 and 302-2, which in the 5GS include NR base stations (gNBs), controlling corresponding (macro) cells 304-1 and 304-2. The base stations 302-1 and 302-2 are generally referred to herein collectively as base stations 302 and individually as base station 302. Likewise, the (macro) cells 304-1 and 304-2 are generally referred to herein collectively as (macro) cells 304 and individually as (macro) cell 304. The RANmay also include a number of low power nodes 306-1 through 306-4 controlling corresponding small cells 308-1 through 308-4. The low power nodes 306-1 through 306-4 can be small base stations (such as pico or femto base stations) or RRHs, or the like. Notably, while not illustrated, one or more of the small cells 308-1 through 308-4 may alternatively be provided by the base stations 302. The low power nodes 306-1 through 306-4 are generally referred to herein collectively as low power nodes 306 and individually as low power node 306. Likewise, the small cells 308-1 through 308-4 are generally referred to herein collectively as small cells 308 and individually as small cell 308. The cellular communications system 300 also includes a core network 310, which in the 5GS is referred to as the 5GC. The base stations 302 (and optionally the low power nodes 306) are connected to the core network 310.

[0050] The base stations 302 and the low power nodes 306 provide service to wireless communication devices 312-1 through 312-5 in the corresponding cells 304 and 308. The wireless communication devices 312-1 through 312-5 are generally referred to herein collectively as wireless communication devices 312 and individually as wireless communication device 312. In the following description, the wireless communication devices 312 are oftentimes UEs, but the present disclosure is not limited thereto.

[0051] Figure 4 illustrates a wireless communication system represented as a 5G network architecture composed of core Network Functions (NFs), where interaction between any two NFs is represented by a point-to-point reference point / interface. Figure 4 can be viewed as one particular implementation of the system 300 of Figure 3.

[0052] Seen from the access side the 5G network architecture shown in Figure 4 comprises a plurality of UEs 312 connected to either a RAN 302 or an Access Network (AN) as well as an AMF 400. Typically, the R(AN) 302 comprises base stations, e.g. such as eNBs or gNBs or similar. Seen from the core network side, the 5GC NFs shown in Figure 4 include a Network Slice Selection Function (NSSF) 402, an Authentication Server Function (AUSF) 404, a Unified Data Management (UDM) 406, the AMF 400, a SMF 408, a Policy Control Function (PCF) 410, and an Application Function (AF) 412.

[0053] Reference point representations of the 5G 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 312 and AMF 400. The reference points for connecting between the AN 302 and AMF 400 and between the AN 302 and UPF 414 are defined as N2 and N3, respectively. There is a reference point, Nil, between theAMF 400 and SMF 408, which implies that the SMF 408 is at least partly controlled by the AMF 400. N4 is used by the SMF 408 and UPF 414 so that the UPF 414 can be set using the control signal generated by the SMF 408, and the UPF 414 can report its state to the SMF 408. N9 is the reference point for the connection between different UPFs 414, and N14 is the reference point connecting between different AMFs 400, respectively. N15 and N7 are defined since the PCF 410 applies policy to the AMF 400 and SMF 408, respectively. N12 is required for the AMF 400 to perform authentication of the UE 312. N8 and N10 are defined because the subscription data of the UE 312 is required for the AMF 400 and SMF 408.

[0054] The 5GC network aims at separating User Plane (UP) and Control Plane (CP). The UP carries user traffic while the CP carries signaling in the network. In Figure 4, the UPF 414 is in the UP and all other NFs, i.e., the AMF 400, SMF 408, PCF 410, AF 412, NSSF 402, AUSF 404, and UDM 406, are in the CP. Separating the UP and CP guarantees each plane resource to be scaled independently. It also allows UPFs to be deployed separately from CP 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.

[0055] The core 5G network architecture is composed of modularized functions. For example, the AMF 400 and SMF 408 are independent functions in the CP. Separated AMF 400 and SMF 408 allow independent evolution and scaling. Other CP functions like the PCF 410 and AUSF 404 can be separated as shown in Figure 4. Modularized function design enables the 5GC network to support various services flexibly.

[0056] Each NF interacts with another NF directly. It is possible to use intermediate functions to route messages from one NF to another NF. In the CP, a set of interactions between two NFs is defined as service so that its reuse is possible. This service enables support for modularity. The UP supports interactions such as forwarding operations between different UPFs.

[0057] Figure 5 illustrates a 5G network architecture using service-based interfaces between the NFs in the CP, instead of the point-to-point reference points / interfaces used in the 5G network architecture of Figure 4. However, the NFs described above with reference to Figure 4 correspond to the NFs shown in Figure 5. 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 Figure 5 the service based interfaces areindicated by the letter "N" followed by the name of the NF, e.g. Namf for the service based interface of the AMF 400 and Nsmf for the service based interface of the SMF 408, etc. Network Exposure Function (NEF) 500 and Network Repository Function (NRF) 502 in Figure 5 are not shown in Figure 4 discussed above. However, it should be clarified that all NFs depicted in Figure 4 can interact with the NEF 500 and the NRF 502 of Figure 5 as necessary, though not explicitly indicated in Figure 4.

[0058] Some properties of the NFs shown in Figures 4 and 5 may be described in the following manner. The AMF 400 provides UE-based authentication, authorization, mobility management, etc. A UE 312 even using multiple access technologies is basically connected to a single AMF 400 because the AMF 400 is independent of the access technologies. The SMF 408 is responsible for session management and allocates Internet Protocol (IP) addresses to UEs. It also selects and controls the UPF 414 for data transfer. If a UE 312 has multiple sessions, different SMFs 408 may be allocated to each session to manage them individually and possibly provide different functionalities per session. The AF 412 provides information on the packet flow to the PCF 410 responsible for policy control in order to support QoS. Based on the information, the PCF 410 determines policies about mobility and session management to make the AMF 400 and SMF 408 operate properly. The AUSF 404 supports authentication function for UEs or similar and thus stores data for authentication of UEs or similar while the UDM 406 stores subscription data of the UE 312. The Data Network (DN), not part of the 5GC network, provides Internet access or operator services and similar.

[0059] An NF may be implemented either as a network element on a dedicated hardware, as a software instance running on a dedicated hardware, or as a virtualized function instantiated on an appropriate platform, e.g., a cloud infrastructure.

[0060] Figure 6 illustrates the system 300 of Figure 3 for one example embodiment for the home-routed roaming scenario. As illustrated, in the example of Figure 6, the system 300 includes a Visited Public Land Mobile Network (VPLMN) and a Home Public Land Mobile Network (HPLMN) each including various NFs such as those illustrated in Figure 6.

[0061] Embodiments of the present disclosure relate to two alternatives for addressing the aforementioned challenges related to ODB, each of which are described below.Alternative 1 - Direct Rejection by (V- / I-)SMF with Indication from AMF

[0062] Direct rejection by (Visited (V)- / Intermediate (I)-)SMF with an indication from AMF: There are two options, Option A and Option B, each of which is described below.

[0063] Option A: In one embodiment, a solution is introduced by adding an indicator that a PDU Session needs to be rejected by the (V- / I-)SMF after the (V- / I-)SMF receives a Nsmf_PDUSession_CreateSMContext Request from the AMF, and an additional Reason or Cause. When the (V- / I-)SMF receives this request with this indicator and cause, the (V- / I-)SMF rejects the PDU Session Establishment Request directly, with the corresponding 5GS Session Management (5GSM) Cause based on the reason in the request, and without any further handling. For example, for the ODB case, the indicator is an indicator that the PDU Session needs to be rejected due to the reason that PDU Session is barred based on the ODBPacketServices value in the AccessAnd Mobi I itySu bscri ption Data .

[0064] In one embodiment, the following updates to 3GPP TS 29.502 implement an embodiment of Option A of Alternative 1:6.1.6.2.2 Type: SmContextCreateData

[0065] An example new chapter 6.1.6.3.x (" Enumeration: EstablishRejectionCause") of 3GPP TS 29.502 for the ODB case is as follows:

[0066] When the Nsmf_PDUSession_CreateSMContext Request includes estabRejectionlnd with "true" value, then:• For Home-Routed PDU Session Establishment, and PDU Session Establishment with I-SMF Insertion: o The V-SMF(for HR roaming), I-SMF(for DTSSA) shall reject the PDU Session Establishment Request, the cause can be determined based on the estabRejectionCause included in the request, e.g. for the ODB, the V- SMF or I-SMF can use the cause "operator determined barring"; or• For Non-Roaming, or LBO PDU Session Establishment: o The SMF shall reject the PDU Session Establishment Request, the cause can be determined based on the estabRejectionCause included in the request, e.g. for the ODB, the SMF can use the cause "operator determined barring" without the SessionManagementSubscription Data retrieval from the UDM.

[0067] Option B: In this option, a specific solution is introduced by adding an indication that PDU Session needs to be rejected by the AMF after the (V- / I-)SMF receives the Nsmf_PDUSession_CreateSMContext Request from the AMF. When the (V- / I-)SMF receives the request with this indication, then the (V- / I-)SMF shall reject the PDU Session Request directly, without any further handling.

[0068] In one embodiment, the following updates to 3GPP TS 29.502 implement an embodiment of Option B of Alternative 1:6.1.6.2.2 Type: SmContextCreateData

[0069] When the Nsmf_PDUSession_CreateSMContext Request includes odblnd with "true" value, then:• For Home-Routed PDU Session Establishment, and PDU Session Establishment with I-SMF Insertion: The V-SMF(for HR roaming), I-SMF(for DTSSA) shall reject the PDU Session Establishment Request with the cause #8 "operator determined barring"; or• For Non-Roaming, or LBO PDU Session Establishment: The SMF shall reject the PDU Session Establishment Request, with the cause #8 "operator determined barring" without the SessionManagementSubscription Data retrieval from the UDM.

[0070] Figure 7 illustrates a process in accordance with Alternative 1, in accordance with an example embodiment of the present disclosure. The steps of the procedure of Figure 7 are as follows.• Step 700. A UE sends, towards the AMF via the RAN (e.g., via a gNB), a PDU Session Establishment Request for a new PDU Session.• Step 702. a) Step 702a: The AMF determines whether the PDU Session Establishment Request is to be rejected, based on subscription data (e.g., of the UE), local configuration, or other information upon receiving the PDU Session Establishment Request. b) Step 702b: If the PDU Session needs to be rejected due to failure of the information checking of Step 702(a), then the AMF only performs NF Discovery for V-SMF according to the Single Network Slice Selection Assistance Information (S-NSSAI) and Tracking Area for Home-Routed roaming, or Deployments Topologies with specific SMF Service Areas (DTSSA) with I-SMF Insertion, i.e. the AMF does not need to discover H- SMF or SMF. Otherwise, the AMF discovers and selects the SMF(s) as usual.• Step 704. If the PDU Session needs to be rejected by the (V- / I-)SMF, the AMF sends a Nsmf_PDUSession_CreateSMContext with estabRejectionInd=true, and the corresponding estabRejectionCause. Otherwise, the AMF sends the Nsmf_PDUSession_CreateSMContext Request to the (V- / I-)SMF as usual.• Step 706. In this embodiment, the V-SMF sends a failure response with Nsmf_PDUSession_CreateSMContext to reject the request, and with a N1 Message PDU Session Establishment Reject with a corresponding cause based on the estabRejectionCause included in the Nsmf_PDUSession_CreateSMContext request, e.g. cause "operator determined barring". In other words, the (V- / I- )SMF sends the PDU Session Establishment Reject message to the UE directly (i.e., without forwarding the request to the H-SMF where the H-SMF would then reject the request due to ODB after the session management subscription data is retrieved from the UDM as would be done if using the existing procedures defined in 3GPP specifications). Note that if the request is not rejected, the V- SMF sends a successful response to the AMF, and then creates the session with H-SMF as shown in Figure 2. o Note that, in an alternative embodiment, in step 706 the V-SMF sends an SmContextCreateError message, rather than a create SM context response message. The error message indicates "operator determined barring" application error.o Note that in another alternative embodiment (i.e., Option B of Alternative 1), in step 704, the AMF alternatively includes the "odblnd" attribute with true value in the Nsmf_PDUSession_CreateSMContext (rather than including estabRejection!nd=true and the corresponding estabRejectionCause). Then, in step 706, the V-SMF will send the failure response to the Nsmf_PDUSession_CreateSMContext Request, and reject the PDU Session Establishment request with "operator determined barring".• Step 708. The AMF forwards the N1 message to the UE.

[0071] In some implementations, Nsmf_PDUSession service includes the following feature.Alternative 2 - Direct Rejection by AMF

[0072] Direct Rejection by the AMF: There are two variations for this alternative:• In one variation, the AMF rejects the PDU Session Establishment Request by transmitting a 5GSM reject message with a corresponding 5GSM Cause.• In another variation, the AMF sends a Downlink (DL) Non-Access Stratum (NAS) Transport message (i.e., a "DL NAS TRANSPORT message") to indicate that the request cannot be forwarded due to a corresponding reason by extending the existing 5GMM Cause / Additional Information or introducing a new attribute to indicate to the UE the reason of rejection.

[0073] In one embodiment, when the PDU Session establishment request needs to be rejected when the request is conflicting with the subscription data, local configuration, or other information:• In one variation, the AMF constructs and sends a Session Management (SM) reject message directly with the corresponding 5GSM cause.o For example, for ODB, the AMF shall send a PDU Session Establishment Reject message with cause #8 "operator determined barring".• In another variation, the AMF sends the DL NAS TRANSPORT message to indicate the request can not be forwarded to the (V- / I-)SMF due to the conflict.

[0074] Figure 8 illustrates a process in accordance with Alternative 2, in accordance with an example embodiment of the present disclosure. The steps of the procedure of Figure 8 are as follows:• Step 800. A UE sends, towards an AMF via the RAN, a PDU Session Establishment Request for a new PDU Session.• Step 802. The AMF determines whether the PDU Session Establishment Request is to be rejected, based on subscription data (e.g., of the UE), local configuration, or other information, upon receiving the PDU Session Establishment Request.• Step 804. If the request is to be rejected, e.g. due to ODB, then: o Step 804a: In one variation, the AMF sends, to the UE, a PDU Session Establishment Reject with a corresponding cause, e.g. ODB. o Step 804b: In another variation, the AMF sends, to the UE, a DL NAS TRANSPORT message with a corresponding cause.■ The cause is, in one embodiment, a new 5GMM Cause to indicate the PDU Session Establishment is rejected due to ODB;■ In another embodiment, the cause is additional (e.g., new) information included in the DL NAS TRANSPORT message to indicate the PDU Session is rejected due to ODB.Further Description

[0075] Certain embodiments may provide one or more of the following technical advantage(s). With embodiments of alternative 1, signaling for- Resource allocation for home-routed roaming, and I-SMF Insertion for nonroaming or LBO; or- Subscription data retrieval for LBO and non-roaming, can be optimized for the scenario that the PDU Session is rejected by the (V- / I-)SMF due to the information (e.g., subscription data) check performed in the AMF, e.g. ODB.

[0076] For alternative 2, the AMF can reject the PDU Session Establishment Request directly, so even without involving the (V- / I-)SMF.

[0077] Besides that, for ODB case, there are two places including the ODBPacketServices - one is in AccessAndMobilitySubscriptionData and the other is in SessionManagementSubscription Data. With this solution, only one ODBPacketServices in the AccessAndMobilitySubscriptionData is needed and, as such, the one in the SessionManagementSubscriptionData can be removed. This will simplify the provisioning system, the data storage in the UDR, and the corresponding Notification from the UDM to the SMF for the modification of this attribute in the SessionManagementSubscriptionData.

[0078] Figure 9 is a schematic block diagram of a network node 900 according to some embodiments of the present disclosure. Optional features are represented by dashed boxes. The network node 900 may be, for example, a network node that implements a NF in the core network 310 (e.g., an AMF, V-UPF, V-SMF, H-SMF, UDM, or the like) or a RAN node such as, e.g., a base station 302 or 306 or a network node that implements all or part of the functionality of the base station 302 or gNB described herein. As illustrated, the network node 900 includes a control system 902 that includes one or more processors 904 (e.g., Central Processing Units (CPUs), Application Specific Integrated Circuits (ASICs), Field Programmable Gate Arrays (FPGAs), and / or the like), memory 906, and a network interface 908. The one or more processors 904 are also referred to herein as processing circuitry. In addition, if the network node 900 is a radio access node (e.g., a base station 302, gNB, or network node that implements at least some of the functionality of the base station 302 or gNB), the network node 900 may include one or more radio units 910 that each includes one or more transmitters 912 and one or more receivers 914 coupled to one or more antennas 916. The radio units 910 may be referred to or be part of radio interface circuitry. In some embodiments, the radio unit(s) 910 is external to the control system 902 and connected to the control system 902 via, e.g., a wired connection (e.g., an optical cable).However, in some other embodiments, the radio unit(s) 910 and potentially the antenna(s) 916 are integrated together with the control system 902. The one or more processors 904 operate to provide one or more functions of the network node 900 as described herein (e.g., one or more functions of a RAN node, AMF, V-UPF, V-SMF, H- SMF, UDM, or the like, as described herein). In some embodiments, the function(s) are implemented in software that is stored, e.g., in the memory 906 and executed by the one or more processors 904.

[0079] Figure 10 is a schematic block diagram that illustrates a virtualized embodiment of the network node 900 according to some embodiments of the present disclosure. Again, optional features are represented by dashed boxes. As used herein, a "virtualized" network node is an implementation of the network node 900 in which at least a portion of the functionality of the network node 900 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, if the network node 900 is a radio access node, the network node 900 may include the control system 902 and / or the one or more radio units 910, as described above. The control system 902 may be connected to the radio unit(s) 910 via, for example, an optical cable or the like. The network node 900 includes one or more processing nodes 1000 coupled to or included as part of a networks) 1002. If present, the control system 902 or the radio unit(s) are connected to the processing node(s) 1000 via the network 1002. Each processing node 1000 includes one or more processors 1004 (e.g., CPUs, ASICs, FPGAs, and / or the like), memory 1006, and a network interface 1008.

[0080] In this example, functions 1010 of the network node 900 described herein (e.g., one or more functions of a RAN node, AMF, V-UPF, V-SMF, H-SMF, UDM, or the like, as described herein) are implemented at the one or more processing nodes 1000 or distributed across the one or more processing nodes 1000 and the control system 902 and / or the radio unit(s) 910 in any desired manner. In some particular embodiments, some or all of the functions 1010 of the network node 900 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) 1000. As will be appreciated by one of ordinary skill in the art, additional signaling or communication between the processing node(s) 1000 and the control system 902 is used in order to carry out at least some of the desired functions 1010. Notably, in some embodiments, the control system 902 may not be included, in which case the radio unit(s) 910 communicate directly with the processing node(s) 1000 via an appropriate network interface(s).

[0081] 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 900 or a node (e.g., a processing node 1000) implementing one or more of the functions 1010 of the network node 900 in a virtualenvironment according to any of the embodiments described herein is provided. In some embodiments, a carrier comprising the aforementioned computer program product is provided. The carrier is one of an electronic signal, an optical signal, a radio signal, or a computer readable storage medium (e.g., a non-transitory computer readable medium such as memory).

[0082] Figure 11 is a schematic block diagram of the network node 900 according to some other embodiments of the present disclosure. The network node 900 includes one or more modules 1100, each of which is implemented in software. The module(s) 1100 provide the functionality of the network node 900 described herein. This discussion is equally applicable to the processing node 1000 of Figure 10 where the modules 1100 may be implemented at one of the processing nodes 1000 or distributed across multiple processing nodes 1000 and / or distributed across the processing node(s) 1000 and the control system 902.

[0083] Any appropriate steps, methods, features, functions, or benefits disclosed herein may be performed through one or more functional units or modules of one or more virtual apparatuses. Each virtual apparatus may comprise a number of these functional units. These functional units may be implemented via processing circuitry, which may include one or more microprocessor or microcontrollers, as well as other digital hardware, which may include Digital Signal Processor (DSPs), special-purpose digital logic, and the like. The processing circuitry may be configured to execute program code stored in memory, which may include one or several types of memory such as Read Only Memory (ROM), Random Access Memory (RAM), cache memory, flash memory devices, optical storage devices, etc. Program code stored in memory includes program instructions for executing one or more telecommunications and / or data communications protocols as well as instructions for carrying out one or more of the techniques described herein. In some implementations, the processing circuitry may be used to cause the respective functional unit to perform corresponding functions according to one or more embodiments of the present disclosure.

[0084] While processes in the figures may show a particular order of operations performed by certain embodiments of the present disclosure, it should be understood that such order is exemplary (e.g., alternative embodiments may perform the operations in a different order, combine certain operations, overlap certain operations, etc.).

Claims

Claims1. A method comprising:• at an Access and Mobility Management Function, AMF, of a core network of a cellular communications system: o receiving (700) a request to establish a Protocol Data Unit, PDU, session for a User Equipment, UE; o determining (702) that establishment of the PDU session is to be rejected; and o sending (704), to a Session Management Function, SMF, of the cellular communications system, a request comprising an indication to reject establishment of the PDU session; and• at the SMF: o receiving (704), from the AMF, the request comprising the indication to reject establishment of the PDU session; and o responsive to receiving (704) the request, sending (706), to the AMF, a failure response to directly reject the request to establish the PDU session for the UE.

2. The method of claim 1, wherein the request sent from the AMF to the SMF is a request to create a session management context associated to the PDU session requested to be established.

3. The method of claim 1 or 2, wherein the request sent from the AMF to the SMF further comprises information that indicates a reason to reject establishment of the PDU session.

4. The method of claim 3, wherein the reason to reject establishment of the PDU session is Operator Determined Barring, ODB.

5. The method of claim 1, wherein the request sent from the AMF to the SMF is a Create Session Management, SM, context request comprising SmContextCreateData, wherein the SmContextCreateData comprises the indication to reject the establishmentof the PDU session and information that indicates a cause of PDU establishment rejection.

6. The method of claim 5, wherein the indicated cause of PDU establishment rejection is Operator Determined Barring, ODB.

7. The method of claim 1 or 2, wherein the indication to reject establishment of the PDU session directly indicates that establishment of the PDU session is rejected due to Operator Determined Barrier, ODB.

8. A method performed by an Access and Mobility Management Function, AMF, of a cellular communications system, the method comprising: receiving (700) a request to establish a Protocol Data Unit, PDU, session for a User Equipment, UE; determining (702) that establishment of the PDU session is to be rejected; and sending (704), to a Session Management Function, SMF, a request comprising an indication to reject establishment of the PDU session.

9. The method of claim 8, wherein the request sent from the AMF to the SMF is a request to create a session management context associated to the PDU session requested to be established.

10. The method of claim 8 or 9, wherein the request sent from the AMF to the SMF further comprises information that indicates a reason to reject establishment of the PDU session.

11. The method of claim 10, wherein the reason to reject establishment of the PDU session is Operator Determined Barring, ODB.

12. The method of claim 8, wherein the request sent from the AMF to the SMF is a Create Session Management, SM, context request comprising SmContextCreateData, wherein the SmContextCreateData comprises the indication to reject the establishmentof the PDU session and information that indicates a cause of PDU establishment rejection.

13. The method of claim 12, wherein the indicated cause of PDU establishment rejection is Operator Determined Barring, ODB.

14. The method of claim 8 or 9, wherein the indication to reject establishment of the PDU session directly indicates that establishment of the PDU session is rejected due to Operator Determined Barrier, ODB.

15. An Access and Mobility Management Function, AMF, for a cellular communications system, the AMF adapted to: receive (700) a request to establish a Protocol Data Unit, PDU, session for a User Equipment, UE; determine (702) that establishment of the PDU session is to be rejected; and send (704), to a Session Management Function, SMF, a request comprising an indication to reject establishment of the PDU session.

16. The AMF of claim 15, further adapted to perform the method of any of claims 9 to 14.

17. A network node for implementing an Access and Mobility Management Function, AMF, for a cellular communications system, the network node comprising: a network interface; and processing circuitry associated with the network interface, the processing circuitry configured to cause the network node to: receive (700) a request to establish a Protocol Data Unit, PDU, session for a User Equipment, UE; determine (702) that establishment of the PDU session is to be rejected; and send (704), to a Session Management Function, SMF, a request comprising an indication to reject establishment of the PDU session.

18. The network node of claim 17, wherein the processing circuitry is further configured to cause the network node to perform the method of any of claims 9 to 14.

19. A non-transitory computer-readable medium comprising instructions that, when executed by processing circuitry of a network node for implementing an Access and Mobility Management Function, AMF, of a cellular communications system, cause the network node to: receive (700) a request to establish a Protocol Data Unit, PDU, session for a User Equipment, UE; determine (702) that establishment of the PDU session is to be rejected; and send (704), to a Session Management Function, SMF, a request comprising an indication to reject establishment of the PDU session.

20. The non-transitory computer-readable medium of claim 19, wherein, when executed by the processing circuitry of the network node, the instructions further cause the network node to perform the method of any of claims 9 to 14.

21. A method performed by a Session Management Function, SMF, of a cellular communications system, the method comprising: receiving (704), from an Access and Mobility Management Function, AMF, of the cellular communications system, a request comprising an indication to reject establishment of a Protocol Data Unit, PDU, session for a User Equipment, UE; and responsive to receiving (704) the request, sending (706), to the AMF, a failure response to reject the request to establish the PDU session for the UE.

22. The method of claim 21, wherein the request received from the AMF is a request to create a session management context associated to the PDU session requested to be established.

23. The method of claim 21 or 22, wherein the request received from the AMF further comprises information that indicates a reason to reject establishment of the PDU session.

24. The method of claim 23, wherein the reason to reject establishment of the PDU session is Operator Determined Barring, ODB.

25. The method of claim 21, wherein the request received from the AMF is a Create Session Management, SM, context request comprising SmContextCreateData, wherein the SmContextCreateData comprises the indication to reject the establishment of the PDU session and information that indicates a cause of PDU establishment rejection.

26. The method of claim 25, wherein the indicated cause of PDU establishment rejection is Operator Determined Barring, ODB.

27. The method of claim 21 or 22, wherein the indication to reject establishment of the PDU session directly indicates that establishment of the PDU session is rejected due to Operator Determined Barrier, ODB.

28. A Session Management Function, SMF, for a cellular communications system, the SMF adapted to: receive (704), from an Access and Mobility Management Function, AMF, of the cellular communications system, a request comprising an indication to reject establishment of a Protocol Data Unit, PDU, session for a User Equipment, UE; and responsive to receiving (704) the request, send (706), to the AMF, a failure response to reject the request to establish the PDU session for the UE.

29. The SMF of claim 28, further adapted to perform the method of any of claims 22 to 27.

30. A network node for implementing a Session Management Function, SMF, for a cellular communications system, the network node comprising: a network interface; and processing circuitry associated with the network interface, the processing circuitry configured to cause the network node to: receive (704), from an Access and Mobility Management Function, AMF, of the cellular communications system, a request comprising an indication to rejectestablishment of a Protocol Data Unit, PDU, session for a User Equipment, UE; and responsive to receiving (704) the request, send (706), to the AMF, a failure response reject the request to establish the PDU session for the UE.

31. The network node of claim 30, wherein the processing circuitry is further configured to cause the network node to perform the method of any of claims 22 to 27.

32. A non-transitory computer-readable medium comprising instructions that, when executed by processing circuitry of a network node for implementing a Session Management Function, SMF, of a cellular communications system, cause the network node to: receive (704), from an Access and Mobility Management Function, AMF, of the cellular communications system, a request comprising an indication to reject establishment of a Protocol Data Unit, PDU, session for a User Equipment, UE; and responsive to receiving (704) the request, send (706), to the AMF, a failure response to reject the request to establish the PDU session for the UE.

33. The non-transitory computer-readable medium of claim 32, wherein, when executed by the processing circuitry of the network node, the instructions further cause the network node to perform the method of any of claims 22 to 27.

34. A method performed by an Access and Mobility Management Function, AMF, of a cellular communications system, the method comprising: receiving (800) a request to establish a Protocol Data Unit, PDU, session for a User Equipment, UE; determining (802) that establishment of the PDU session is to be rejected; and sending (804a or 804b), to the UE, a message that indicates that the request to establish the PDU session is rejected, the message comprising information that indicates a reason that the request to establish the PDU session is rejected.

35. The method of claim 34, wherein the message sent to the UE is a PDU session establishment reject message comprising the information that indicates the reason that the request to establish the PDU session is rejected.

36. The method of claim 34, wherein the message sent to the UE is a downlink, DL, Non-Access Stratum, NAS, transport message comprising the information that indicates the reason that the request to establish the PDU session is rejected.

37. The method of any of claims 34 to 36, wherein the reason to reject establishment of the PDU session is Operator Determined Barring, ODB.

38. The method of any of claims 34 to 37, the AMF rejects the request to establish the PDU session without involving a Session Management Function, SMF.

39. An Access and Mobility Management Function, AMF, for a cellular communications system, the AMF adapted to: receive (800) a request to establish a Protocol Data Unit, PDU, session for a User Equipment, UE; determine (802) that establishment of the PDU session is to be rejected; and send (804a or 804b), to the UE, a message that indicates that the request to establish the PDU session is rejected, the message comprising information that indicates a reason that the request to establish the PDU session is rejected.

40. The AMF of claim 39, further adapted to perform the method of any of claims 35 to 38.

41. A network node for implementing an Access and Mobility Management Function, AMF, for a cellular communications system, the network node comprising: a communication interface; and processing circuitry associated with the communication interface, the processing circuitry configured to cause the network node to: receive (800) a request to establish a Protocol Data Unit, PDU, session for a User Equipment, UE;determine (802) that establishment of the PDU session is to be rejected; and send (804a or 804b), to the UE, a message that indicates that the request to establish the PDU session is rejected, the message comprising information that indicates a reason that the request to establish the PDU session is rejected.

42. The network node of claim 41, wherein the processing circuitry is further configured to cause the network node to perform the method of any of claims 35 to 38.

43. A non-transitory computer-readable medium comprising instructions that, when executed by processing circuitry of a network node for implementing an Access and Mobility Management Function, AMF, of a cellular communications system, cause the network node to: receive (800) a request to establish a Protocol Data Unit, PDU, session for a User Equipment, UE; determine (802) that establishment of the PDU session is to be rejected; and send (804a or 804b), to the UE, a message that indicates that the request to establish the PDU session is rejected, the message comprising information that indicates a reason that the request to establish the PDU session is rejected.

44. The non-transitory computer-readable medium of claim 43, wherein, when executed by the processing circuitry of the network node, the instructions further cause the network node to perform the method of any of claims 35 to 38.

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