Method, method for releasing an n2 connection associated with a user equipment, appliance, system and media readable by a non-transiential processor

Abstract

A network architecture and methods for managing packet data unit (PDU) sessions on a network are provided. The methods include PDU session establishment procedures, PDU session modification procedures, PDU session state transfer procedures, PDU session release procedures, and user equipment (UE) handover procedures.

Description

METHOD, METHOD FOR RELEASING AN N2 CONNECTION ASSOCIATED WITH A USER EQUIPMENT, APPLIANCE, SYSTEM AND MEDIA READABLE BY A NON-TRANSIENTIAL PROCESSOR CROSS-REFERENCE FOR RELATED ORDERS

[001] This application relates to U.S. Provisional Patent Application No. 62 / 444,251, entitled “System and Methods for Session Management,” filed January 9, 2017, to U.S. Provisional Patent Application No. 62 / 448,239 entitled “System and Methods for Session Management,” filed January 19, 2017, to U.S. Provisional Patent Application No. 62 / 455,412, entitled “System and Methods for Session Management,” filed February 6, 2017, to U.S. Provisional Patent Application No. 62 / 460,533 entitled “System and Methods for Session Management,” filed February 17, 2017, to U.S. Provisional Patent Application No. 62 / 472,720, entitled "System and Methods for Session Management," filed March 17, 2017, with U.S. Provisional Patent Application No. 62 / 492,045, entitled "System and Methods for Session Management," filed April 28, 2017, with U.S. Provisional Patent Application No.U.S. Patent Application No. 62 / 503,117, entitled “System and Methods for Session Management,” filed May 8, 2017, to U.S. Provisional Patent Application No. 62 / 521,922, entitled “System and Methods for Session Management,” filed June 19, 2017, the contents of which are incorporated herein by reference, including all filed attachments. This patent application also claims priority to U.S. Patent Application No. 15 / 862,194, filed January 4, 2018, and entitled “System and Methods for Session Management,” which is also incorporated herein by reference as if reproduced in its entirety. FIELD OF THE INVENTION

[002] The present invention relates to the field of communications. Petition 870250082301, dated 12 / 09 / 2025, page 8 / 556 2 / 264 of networking and, in particular, to the system and methods for managing packet data unit (PDU) session-related matters. FUNDAMENTALS

[003] When a user device (UE) initiates a new data session on a fifth-generation (5G) network, the UE attaches (i.e., connects or registers) to the network. A network session management function will oversee connection management tasks. Additionally, when a UE is already connected to a network, the session management function can oversee changes to the UE's network connection. Current session management procedures address signaling overhead and connection time issues.

[004] This background information is provided to disclose information that the applicant believes to be of possible relevance to the present invention. No admission is necessarily intended, nor should it be construed, that any prior information constitutes prior art contrary to the present invention. SUMMARY

[005] One object of the embodiments of the present invention is to provide a system and methods for session management of a communications network.

[006] According to embodiments of the present invention, a method for releasing a packet data unit (PDU) session is provided. The method comprises determining the triggering of a PDU session release, sending an N4 Session Release Request message to a User Plan Function (UPF), receiving an N4 Session Release Response message from the UPF, sending an N11 Request with PDU Session Release Command to an Access and Mobility Function (AMF), receiving an N11 Response with PDU Session Release Acknowledgment from the AMF, and sending an N11 message to the AMF.

[007] According to embodiments of the present invention, also Petition 870250082301, dated 12 / 09 / 2025, page 9 / 556 3 / 264 provides a handover method comprising receiving an N2 Path Switching Request from a Target Radio Access Network (T-RAN), sending an N11 Message to a Session Management Function (SMF), receiving N11 Message Acknowledgment from the SMF, and sending an N2 Path Switching Request Acknowledgment to the T-RAN. BRIEF DESCRIPTION OF THE FIGURES

[008] Other features and advantages of the present invention will become apparent from the following detailed description, taken in combination with the accompanying drawings, in which: Figure 1 illustrates, in a block diagram, a computing system that can be used to implement the devices and methods revealed here; Figure 2A illustrates, in a component diagram, an example of a communication network architecture; Figure 2B illustrates, in a component diagram, an example of a next-generation (NG) non-roaming architecture (such as 5G mobile wireless networks), in a point-to-point reference point representation; Figure 2C is a block diagram illustrating a service-based view of a 5G Core Network system architecture; Figure 3 illustrates, in a message flowchart, an example of methods for attaching and re-attaching a UE to a data network; Figure 4 illustrates, in a component diagram, an example of a Session-IDLE state model; Figure 5 illustrates, in a component diagram, an example of a Session-ACTIVE state model; Figure 6A illustrates, in a state diagram, an example of a session management state model in a UE; Figure 6B illustrates, in a state diagram, an example of a session management state model in an SMF; Petition 870250082301, dated 12 / 09 / 2025, page 10 / 556 4 / 264 Figure 6C illustrates, in a component diagram, an example of a session management state model for multiple PDU sessions; Figure 7 illustrates, in a message flowchart, an example of a session establishment procedure, according to an embodiment of the present invention; Figure 8 illustrates, in a message flowchart, an example of the procedure for subscribing to SMF-AMF EU mobility information, according to a session establishment procedure modality; Figure 9 illustrates, in a message flowchart, an example of the SMF-UDM UE context update procedure, according to a session establishment procedure modality; Figure 10 illustrates, in a message flowchart, an example of an AMFUDM UE context update procedure, according to a session establishment procedure modality; Figure 11 illustrates, in a message flowchart, an example of an SMF-PCF session update procedure, according to a session establishment procedure modality; Figure 12 illustrates, in a flowchart, an example of a method for establishing a session, according to the session establishment procedure; Figure 13 illustrates, in a message flowchart, an example of a session modification procedure, according to an embodiment of the present invention; Figure 14 illustrates, in a flowchart, an example of a method for modifying a session, according to the session modification procedure; Figure 15 illustrates, in a message flowchart, an example of a session release procedure, according to Petition 870250082301, dated 12 / 09 / 2025, page 11 / 556 5 / 264 an embodiment of the present invention; Figure 16 illustrates, in a flowchart, an example of a session release method, according to the session release procedure; Figure 17 illustrates, in a flowchart, another example of a session release method, according to the session release procedure; Figure 18 illustrates, in a message flowchart, an example of a PDU session connection state transition procedure, according to an embodiment of the present invention; Figure 19 illustrates, in a flowchart, an example of a method for performing a state transition, according to the PDU session connection state transition procedure; Figure 20 illustrates, in a message flowchart, an example of an RRC suspension procedure, according to an embodiment of the present invention; Figure 21 illustrates, in a flowchart, an example of a method for transitioning from one session state to another, according to the RRC suspension procedure; Figure 22 illustrates, in a flowchart, another example of a session state transition method, according to the RRC suspension procedure; Figure 23 illustrates, in a message flowchart, an example of an RRC resumption procedure, according to an embodiment of the present invention; Figure 24 illustrates, in a flowchart, an example of a method for transitioning between sessions, according to the RRC resumption procedure; Figure 25 illustrates, in a flowchart, an example of a session state transition method, according to the RRC resumption procedure; Figure 26 illustrates, in a message flowchart, an example of a Session-IDLE state transition procedure. Petition 870250082301, dated 12 / 09 / 2025, page 12 / 556 6 / 264 of individual PDU, according to an embodiment of the present invention; Figure 27 illustrates, in a flowchart, an example of a session state transition method, according to the individual PDU Session-IDLE state transition procedure; Figure 28 illustrates, in a flowchart, another example of a session state transition method, according to the individual PDU Session-IDLE state transition procedure; Figure 29 illustrates, in a message flowchart, another example of a PDU Session-ACTIVE state transition procedure, according to an embodiment of the present invention; Figure 30 illustrates, in a message flowchart, an example of a PDU Session-ACTIVE state transition procedure, according to an embodiment of the present invention; Figure 31 illustrates, in a flowchart, an example of a method for performing a Session-ACTIVE state transition, according to the PDU's Session-ACTIVE state transition procedure; Figure 32 illustrates, in a message flowchart, an example of a PDU Session-ACTIVE state transition procedure, according to an embodiment of the present invention; Figure 33 illustrates, in a flowchart, an example of a session transition method, according to the PDU's Session-ACTIVE state transition procedure; Figure 34 illustrates, in a component diagram, an example of a "EU CN Status Update" service procedure; Figure 35 illustrates, in a component diagram, an example of a "PDU Session Modification" service procedure; Figure 36 illustrates, in a component diagram, a Petition 870250082301, dated 12 / 09 / 2025, page 13 / 556 7 / 264 Example of a service procedure for Obtaining EU Policy; Figure 37 illustrates, in a component diagram, an example of a "UE Context Update" service procedure; Figure 38 illustrates, in a component diagram, an example of a "EU Context Update" service procedure; and Figure 39 is a message flowchart illustrating an example method of an embodiment of the present invention. Figure 40 is a message flowchart illustrating an example method of an embodiment of the present invention. Figure 41 illustrates, in a message flowchart, an example of a PDU session deactivation and N2 release procedure, according to an embodiment of the present invention. Figure 42 illustrates, in a flowchart, an example of a method for releasing an N2 connection and disabling PDU sessions, according to the PDU session disabling and N2 release procedure. Figure 43 illustrates, in a flowchart, another example of a method for disabling a PDU session, according to the PDU session disabling procedure. Figure 44 illustrates, in a message flowchart, another example of a PDU session deactivation procedure, according to an embodiment of the present invention. Figure 45 illustrates, in a flowchart, an example of a method for disabling a PDU session, in accordance with the PDU session disabling procedure in Figure 44. Figure 46 illustrates, in a flowchart, another example of a method for disabling a PDU session, in accordance with the PDU session disabling procedure in Figure 44. Figure 47 illustrates, in a message flowchart, another example of a state transition procedure. (Session Petition 870250082301, dated 12 / 09 / 2025, page 14 / 556) 8 / 264 ACTIVE, according to an embodiment of the present invention. Figure 48 illustrates, in a flowchart, an example of a session transition method, according to the Session-ACTIVE state transition procedure in Figure 47. Figure 49 illustrates, in a flowchart, another example of a session transition method, according to the Session-ACTIVE state transition procedure in Figure 47. Figure 50 illustrates, in a message flowchart, an example of a service request procedure, according to an embodiment of the present invention. Figure 51 illustrates, in a message flowchart, an example of a service request procedure (5100), according to an embodiment of the present invention. Figure 52A illustrates, in a state diagram, an example of a session management state model in a UE, according to an embodiment of the present invention. Figure 52B illustrates, in a state diagram, an example of a session management state model in an AMF and / or an SMF, according to an embodiment of the present invention. Figure 53 illustrates, in a message flowchart, an example of an Xn-based inter-NG RAN handover procedure without UPF relocation, according to an embodiment of the present invention. Figure 54 illustrates, in a flowchart, an example of a UE handover method from a source RAN to a target RAN, according to the Xn-based inter-NG RAN handover procedure of Figure 53. Figure 55 illustrates, in a flowchart, another example of a UE handover method from a source RAN to a target RAN, according to the Xn-based interNG RAN handover procedure of Figure 53. Figure 56 illustrates, in a message flowchart, an example of an Xn-based interNG RAN handover procedure with function relocation. Petition 870250082301, dated 12 / 09 / 2025, page 15 / 556 9 / 264 user plan, according to an embodiment of the present invention. Figure 57 illustrates, in a message flowchart, an example of an N3 reconnection procedure triggered by UL data, according to an embodiment of the present invention. Figure 58 illustrates, in a message flowchart, an example of an N3 reconnection procedure triggered by DL data, according to an embodiment of the present invention. Figure 59 illustrates, in a message flowchart, an example of a PDU Session Deactivation and N2 Release procedure, according to embodiments of the present invention. Figure 60 illustrates, in a message flowchart, another example of a PDU Session Deactivation and N2 Release procedure, according to embodiments of the present invention. Figure 61 illustrates, in a message flowchart, an example of a PDU session release procedure triggered by the UE, PCF, or SMF, according to the embodiments of the present invention. Figure 62 illustrates, in a message flowchart, another example of a PDU session release procedure triggered by the UE or the SMF, according to the embodiments of the present invention. Figure 63 illustrates, in a message call diagram, an example of an Xn-based interNG(R)AN handover procedure without user plane function relocation and with session deactivation, according to embodiments of the present invention. Figure 64 illustrates, in a message flowchart, an example of a Service Request Triggered by UE procedure, according to embodiments of the present invention. Figure 65 illustrates, in a message flowchart, an example of a delayed path switching procedure triggered by DL data without a UPF relocation, according to Petition 870250082301, dated 12 / 09 / 2025, page 16 / 556 10 / 264 with embodiments of the present invention. Figure 66 illustrates, in a message flowchart, an example of a delayed path switching procedure triggered by UL data with UPF re-selection, according to the embodiments of the present invention. Figure 67 illustrates, in a message flowchart, an example of a delayed path switching procedure triggered by DL data with UPF re-selection, according to embodiments of the present invention. Figure 68 illustrates, in a message flowchart, an example of a UPF reselection procedure, according to embodiments of the present invention. Figure 69 illustrates, in a message flowchart, an example of a procedure for releasing UE context in an AN, according to embodiments of the present invention. Figure 70 illustrates, in a message flowchart, an example of a procedure for a PDU session release requested by UE or CN for Non-Roaming and Roaming with Local Separation, according to embodiments of the present invention. Figure 71 illustrates, in a message flowchart, an example of a procedure for a PDU session release requested by UE or CN for routed home roaming, according to embodiments of the present invention. Figure 72 illustrates, in a message flowchart, an example of an Xn-based interNG(R)AN handover procedure without user plane function relocation, according to embodiments of the present invention. Figure 73 illustrates, in a message flowchart, an example of an Xn-based interNG(R)AN handover procedure with user plane function relocation, according to embodiments of the present invention. Figure 74 illustrates, in a message flowchart, a Petition 870250082301, dated 12 / 09 / 2025, page 17 / 556 11 / 264 Example of a Service Request procedure triggered by a UE, according to embodiments of the present invention. Figure 75 illustrates, in a message flowchart, an example of a Service Request procedure triggered by UE in the CM-CONNECTED state, according to embodiments of the present invention. Figure 76 illustrates, in a message flowchart, an example of a Network-Triggered Service Request procedure, according to embodiments of the present invention. Figure 77 illustrates, in a message flowchart, an example of a Service Request procedure triggered by UE in the CM-CONNECTED state, according to embodiments of the present invention. Figure 78 illustrates, in a message flowchart, an example of an intra-AMF, inter-NG-RAN node handover procedure without an Xn interface, according to embodiments of the present invention. Figure 79 illustrates, in a message flowchart, an example of an N2 Release procedure, which is also known as UE Context Release in the AN procedure, according to embodiments of the present invention. Figure 80 is a message flowchart illustrating an example of PDU session release requested by UE or network for non-roaming and roaming with local separation, according to embodiments of the present invention. Figure 81 is a message flowchart illustrating an example procedure for releasing UE context in the AN, according to embodiments of the present invention. Figures 82A and 82B are a message flowchart illustrating an example of a Service Request Triggered by UE procedure, according to embodiments of the present invention. Figures 83A and 83B are a message flowchart illustrating an example of a Service Request procedure. Petition 870250082301, dated 12 / 09 / 2025, p. 18 / 556 12 / 264 Activated by UE in the CM-CONNECTED state, according to embodiments of the present invention.

[009] It will be noted that, throughout the attached drawings, similar features are identified by similar reference numbers. DETAILED DESCRIPTION

[0010] Embodiments of the present invention are directed to session management procedures for a communications network.

[0011] As used herein, a network or communication network may serve multiple devices including, but not necessarily limited to, wireless devices. Such a network may include a radio access portion and a backhaul portion. The network may further comprise multiple virtualized components. A prime example of such a network is a 5G network, which is reconfigurable and capable of network slicing.

[0012] Network slicing relates to the ability of a network, such as a 5G communication network accessible by wireless devices, to provide multiple logical network slices on demand, with each network slice operating as a substantially separate network for different market scenarios that demand diverse requirements. The operational features and parameters of each network slice can be customized to the service requirements. The configuration of the network slices can be based on software-defined networking, network function virtualization, and network orchestration.

[0013] One use of network slicing is in core networking. Through the use of network slicing, different service providers can have distinct core networks that run on the same physical set of network and computing resources. This can also be used to create a virtual network dedicated to specific types of network traffic. It should be understood that this discussion is not intended to exclude the application of slicing. Petition 870250082301, dated 12 / 09 / 2025, page 19 / 556 13 / 264 network to the radio access edge of the radio access network (RAN), which can use specific functionality to support multiple network slices or resource partitioning for different network slices. To provide performance guarantees, network slices can be isolated from each other, so that one slice does not negatively affect the other slices. Isolation is not restricted to different types of services, but also allows the operator to deploy multiple instances of the same network partition.

[0014] Network slicing allows the instantiation of separate network slices, directed respectively to different network services. This allows different types of traffic to be isolated from each other by assigning each type of traffic to a different slice. Each slice can have characteristics adapted to the needs of the traffic flow it carries. Such needs may include different packet processing requirements, different service requirements, and different quality of service (QoS) requirements. Different network slices corresponding to different allocations of grouped resources can offer different services to different clients, or groups of clients.Different services can be supported by different network slices (a network slice can be considered a type of custom virtual network), where the different network slices (i.e., different custom virtual networks) are substantially separated from each other from the client's point of view, although they may share common physical network resources. The pooled resources can be commercially available hardware components, configurable through virtualization approaches such as NFV, to support various network functionalities to support the operations of the network slices.

[0015] The session management functionality in a Petition 870250082301, dated 12 / 09 / 2025, page 20 / 556 The 14 / 264 network is responsible for configuring Internet Protocol (IP) or non-IP traffic connectivity for a user device (UE), as well as managing the user plane for that connectivity. Network functions within the next-generation (NG) control plane may have service-based interfaces to services that can be used by authorized network functions.

[0016] Figure 1 is a block diagram illustrating a computing system 100 that can be used to implement devices and methods disclosed herein. Specific devices may utilize all the components shown or only a subset of the components, and the levels of integration may vary from device to device. Furthermore, a device may contain multiple instances of a component, such as multiple processing units, processors, memories, transmitters, receivers, etc. The computing system 100 includes a processing unit 102. The processing unit 102 includes a central processing unit (CPU) 104, memory 106, and may also include a mass storage device 108, a video adapter 110, and an I / O interface 112 connected to a bus 114.

[0017] Bus 114 may be one or more of any type of various bus architectures, including a memory bus or memory controller, a peripheral bus, or a video bus. CPU 104 may comprise any type of electronic data processor. Memory 106 may comprise any type of non-transient system memory, such as static random access memory (SRAM), dynamic random access memory (DRAM), synchronous DRAM (SDRAM), read-only memory (ROM), or a combination thereof. Memory 106 may include ROM for use in initialization and DRAM for program and data storage for use during program execution. Petition 870250082301, dated 12 / 09 / 2025, page 21 / 556 15 / 264

[0018] Mass storage 108 may comprise any type of non-transient storage device configured to store data, programs, and other information and to make the data, programs, and other information accessible via the bus 114. Mass storage 108 may comprise, for example, one or more of a solid-state drive, hard disk drive, magnetic disk drive, or optical disk drive.

[0019] The video adapter 110 and the I / O interface 112 provide interfaces for connecting external input and output devices to the processing unit 102. As illustrated, examples of input and output devices include a display 116 connected to the video adapter 110 and a mouse / keyboard / printer 118 connected to the I / O interface 112. Other devices may be connected to the processing unit 102, and more or fewer interface cards may be used. For example, a serial interface such as the Universal Serial Bus (USB) (not shown) may be used to provide an interface to an external device.

[0020] The processing unit 102 may also include one or more network interfaces 120, which may comprise wired links, such as an Ethernet cable, and / or wireless links to access different nodes or networks. The network interfaces 120 allow the processing unit 102 to communicate with remote units across networks. For example, the network interfaces 120 may provide wireless communication through one or more transmitters / transmitting antennas and one or more receivers / receiving antennas. The processing unit 102 may be coupled to a local area network 122 or a wide area network for data processing and communications with remote devices, such as other processing units, the Internet, or remote storage facilities. Petition 870250082301, dated 12 / 09 / 2025, page 22 / 556 16 / 264

[0021] Figure 2A illustrates, in a component diagram, an example of a communications network architecture 200. The communications network architecture 200 comprises a user equipment (UE) 202, an access network (AN) 204, a core network (CN) 206, and a data network (DN) 208. An example of an AN 204 is a radio access network (RAN). The term (R)AN is used in this description to indicate that an AN and / or a RAN may be applied. UE 202 communicates with DN 208 via (R)AN 204 and CN 206. Message packet data units (PDUs) between UE 202 and DN 208 pass through (R)AN 204 and CN 206. A DN 208 can be a public network operator, a private data network such as a local area data network (LADN), an intra-operator data network, or any other type of data network.

[0022] In an uplink (UL) direction, user plane (UP) PDUs pass from UE 202 to (R)AN 204 via a communication link. (R)AN 204 forwards the UP PDUs to CN 206, which then forwards the UP PDUs to DN 208. In a downlink (DL) direction, DL PDUs pass from DN 208 to CN 206, which forwards the DL PDUs to (R)AN 204, which then forwards the DL PDUs to UE 202. The CP functionality on CN 206 configures UP functions on CN 206 to provide traffic handling functionality for a session. One or more UP functions per session can be enabled and configured by the CP feature for a given UP scenario.

[0023] The connections between the components of the 200 communication network architecture can be adapted to any communication channel. For next-generation (NG) architectures, the connection between (R)AN 204 and the CP of CN 206 can be via an NG2 interface. The connection between (R)AN 204 and the UP of CN 206 can be via an NG3 interface. The connection between the UP of CN 206 and DN 208 can be via an NG6 interface. Petition 870250082301, dated 12 / 09 / 2025, p. 23 / 556 17 / 264

[0024] Figure 2B illustrates, in a component diagram, an example of a non-roaming NG architecture (such as 5G mobile wireless networks) 210, in a point-to-point reference point representation. The non-roaming NG architecture 210 comprises UE 202, (R)AN 204, CN 206, an application function (AF) 250 that is outside CN 206 and DN 208. CN 206 comprises a UP function module (UPF) 212 and CP functions. The CP functions include an Authentication Server Function (AUSF) 214, a Unified Data Management (UDM) 216, an Access and Mobility Management (AMF) 218, a Session Management (SMF) 220, and a Policy Control Function (PCF) 222. The AMF 218 manages the termination of the NG1 and NG2 signaling interfaces, the forwarding of signaling messages from UE 202 and (R)AN 204 to SMF 220, and the management of mobility and security procedures for UE 202.The SMF manages the establishment of the UP connection between UE 202 and DN 208. PCF 222 provides policies for different network functions to handle a UE session, such as QoS, mobility management, session management, and billing policies. UDM 216 provides storage management for network and user information, and security measures to protect the data. AUSF 214 provides security functions such as authenticating user requests and users, and providing security keys to encrypt data transmitted across interfaces. AF 224 can be any application server outside the 3GPP network that provides control information between external applications and CN 206. For example, an IMS server can be an AF 224. UPF 212 provides user plane functions such as mapping IP packets to QoS flows, packet forwarding, traffic metering, and report preparation and sending.The (R)AN 204 provides an air interface connection. Petition 870250082301, dated 12 / 09 / 2025, page 24 / 556 18 / 264 for EU 202 and forwards packets between EU 202 and CN UPF 212.

[0025] The CN 206 components in the non-roaming NG 210 architecture can be implemented as software modules on one or more servers. Figure 2B illustrates an example of possible interfaces between some of the components. Table 1 shows the communication interfaces used by some of the components in Figure 2B. • Component • Interface • Component • UE 202 • NG1 • AMF 218 • (R)AN 204 • NG2 • AMF 218 • (R)AN 204 • NG3 • UPF 212 • UPF 212 • NG4 • SMF 220 • PCF 222 • NG5 • AF 224 • UPF 212 • NG6 • DN 208 • SMF 220 • NG7 • PCF 220 • AMF 218 • NG8 • UDM 216 • UDM 216 • NG10 • SMF 220 • AMF 218 • NG11 • SMF 220 • AUSF 214 • NG12 • AMF 218 • AUSF 214 • NG13 • UDM 216 • AMF 218 • NG14 • AMF 218 • AMF 218 • NG15 • PCF 222 • Table 1: Interfaces used by some components of a non-roaming NG architecture

[0026] Figure 2C illustrates a service-based architecture 226 for a 5G or Next Generation Core Network (5GCN / NGCN / NCN). This illustration depicts logical connections between nodes and functions, and the connections shown should not be interpreted as direct physical connections. UE 202 forms a radio access network connection with a Radio Access Network ((R)AN) node 228 (which may, for example, be a gNB Node). Petition 870250082301, dated 12 / 09 / 2025, page 25 / 556 19 / 264 is connected to a User Plane Function CN (UP) (UPF) 212, as a UP Gateway, through a network interface, providing a defined interface, such as an N3 interface. UPF 212 provides a logical connection to a data network (DN) 208 through a network interface, such as an N6 interface. The radio access network connection between UE 202 and the (R)AN node 226 can be referred to as a Data Radio Carrier (DRB).

[0027] DN 208 may be a data network used to provide an operator service, or it may be outside the scope of the Third Generation Partnership Project (3GPP) standardization, such as the Internet, a network used to provide third-party services, and in some embodiments DN 208 may represent an Edge Computing network or resource, such as a Mobile Edge Computing (MEC) network.

[0028] UE 202 also connects to Access and Mobility Management Function (AMF) 218 ​​via a logical N1 connection (although the physical connection path is not direct). AMF 218 is responsible for authenticating and authorizing access requests, as well as mobility management functions. AMF 218 may perform other roles and functions as defined by 3GPP Technical Specification (TS) 23.501. In a service-based view, AMF 218 may communicate with other core network control plane functions via a service-based interface denoted as Namf.

[0029] Session Management Function (SMF) 220 is a network function responsible for allocating and managing IP addresses assigned to an ED, as well as selecting a UPF 212 (or a specific instance of a UPF 212) for traffic associated with a particular UE 202 session. It will be appreciated that there will typically be multiple SMFs 220 in the 226 network, each of which may be associated with a respective group of UE 202 nodes. Petition 870250082301, dated 12 / 09 / 2025, p. 26 / 556 20 / 264 of (R)AN 2282 or UPFs 212. The SMF 220 can communicate with other core network functions, in a service-based view, through a service-based interface denoted as Nsmf. The SMF 220 can also connect to a UPF 212 through a logical interface, such as the N4 network interface.

[0030] The Authentication Server Function (AUSF) 214 provides authentication services to other network functions through a service-based Nausf interface.

[0031] A Network Exposure Function (NEF) 230 can be deployed on the network to allow servers, functions, and other entities, such as those outside a trusted domain, to have exposure to services and resources within the network. In one such example, an NEF 230 can act as a proxy between an application server outside the illustrated network and network functions such as the Policy Control Function (PCF) 222, the SMF 220, the UDM 216, and the AMF 218, so that the external application server can provide information that may be useful in configuring parameters associated with a data session. The NEF 230 can communicate with other network functions through a service-based Nnef network interface. The NEF 230 can also have an interface for non-3GPP functions.

[0032] A Network Repository Function (NRF) 232 provides network service discovery functionality. NRF 232 can be specific to the Public Terrestrial Mobility Network (PLMN) or to the network operator with which it is associated. The service discovery feature can allow network functions and UEs connected to the network to determine where and how to access existing network functions, and can present the Nnrf service-based interface.

[0033] The PCF 222 communicates with other network functions through a service-based Npcf interface and can be used to provide policies and rules to other network functions, including those within the control plane. Compliance Petition 870250082301, dated 12 / 09 / 2025, p. 27 / 556 21 / 264 and the application of policies and rules are not necessarily the responsibility of PCF 222, and instead are typically the responsibility of the functions to which PCF 222 transmits the policy. In one example, PCF 222 might transmit policy associated with session management to SMF 220. This can be used to enable a unified policy framework with which network behavior can be governed.

[0034] A Unified Data Management (UDM) Function 216 may present a service-based Nudm interface to communicate with other network functions and may provide data storage resources for other network functions. Unified data storage can enable a consolidated view of network information that can be used to ensure that the most relevant information can be made available to different network functions from a single resource. This can facilitate the implementation of other network functions, as they do not need to determine where a specific type of data is stored on the network. The UDM 216 may employ an interface, such as Nudr, to connect to a UDR (User Data Repository) 234.PCF 222 may be associated with UDM 216 because it may be involved with requesting and providing subscription policy information for UDR 234, but it should be understood that typically PCF 222 and UDM 216 are independent functions.

[0035] PCF 222 may have a direct interface with UDR 234 or may use the Nudr interface to connect to UDR 234. UDM 216 may receive requests to retrieve content stored in UDR 234 or requests to store content in UDR 234. UDM 216 is typically responsible for functionality such as credential processing, location management, and subscription management. UDR 234 may also support any or all of the Authentication Credential Processing, User Identification handling, Petition 870250082301, dated 12 / 09 / 2025, page 28 / 556 22 / 264 Access Authorization, Registration / Mobility Management, Subscription Management, and Short Message Service (SMS) Management. The UDR 234 is typically responsible for storing data provided by the UDM 216. The stored data is typically associated with policy profile information (which may be provided by the PCF 222) that controls access rights to the stored data. In some embodiments, the UDR 234 may store policy data as well as user subscription data, which may include any or all subscription identifiers, security credentials, mobility and access-related subscription data, and session-related data.

[0036] Application Function (AF) 224 represents the non-data plane (also referred to as the non-user plane) functionality of an application deployed in a network operator domain and within a 3GPP-compliant network. AF 224 interacts with other core network functions through a service-based NAF interface, and can access network capacity exposure information as well as provide application information for use in decisions such as traffic routing. AF 224 can also interact with functions such as PCF 222 to provide application-specific input in policy enforcement and policy decisions. It should be understood that in many situations, AF 224 does not provide network services to other NFs and instead is often seen as a consumer or user of services provided by other NFs. An application outside the 3GPP network can perform many of the same functions as AF 224 through the use of NEF 230.

[0037] UE 202 communicates with network functions that are in User Plane (UP) 236 and Control Plane (CP) 238. UPF 212 is part of CN UP 236 (DN 208 being outside the 5GCN). Node (R)AN 228 can be considered part of a user plane, but because it is not strictly part of the CN, it is not Petition 870250082301, dated 12 / 09 / 2025, page 29 / 556 23 / 264 is considered part of CN UP 236 or UPF 212. AMF 218, SMF 220, AUSF 214, NEF 230, NRF 232, PCF 222, and UDM 216 are functions that reside in CN CP 238 and are often referred to as Control Plane Functions. AF 224 may communicate with other functions within CN CP 238 (directly or indirectly through NEF 230), but is typically not considered part of CN CP 238.

[0038] Experts in the art will appreciate that there can be a plurality of UPFs connected in series between node (R)AN 228 and DN 208, and multiple data sessions to different DNs can be accommodated through the use of multiple UPFs in parallel.

[0039] Figure 3 illustrates, in a message flowchart, an example of methods (300) of attaching (305) and re-attaching (375) a UE 202 to a data network 208. The attach method (305) comprises the UE 204 sending an initial attachment request to the NA 204 (310), including the UE capability and, optionally, the requested service and network slice selection assistance information (NSSAI). The NA 204 forwards the attachment request to the AMF 218. The AMF 218 determines which slice(s) the UE 204 has selected by accessing a subscriber repository and then authenticates the UE 204 (320) to verify that the UE 204 is permitted to access the network. The AMF 218 then checks the UE mobility policy (330) to verify that the UE can access the network at this location. AMF 218 selects the appropriate network slice function SMF 220 based on information received from UE 204 in the attachment request and profile information in a subscriber repository.AMF 218 also interacts with AUSF 214 to perform the slice authorization / authentication procedure by verifying the UE identity with the subscriber repository. The procedure determines whether UE 204 is authorized to access that slice. Optionally, a configuration of the UP (360) connections for a specific UE pattern or slice type can be used. Petition 870250082301, dated 12 / 09 / 2025, page 30 / 556 24 / 264 executed. AMF 218 can then send an attachment response to UE 202 via AN 204. The attachment response includes a session management - network slice selection assistance information (SM-NSSAI), a temporary UE identifier (Temp UE ID), and MM parameters. When UE 204 receives the SM-NSSAI, Temp UE ID, and mobility management (MM) parameters, UE 204 can use the information to assist network slice selection (e.g., when the UE detaches from the network and then reattaches to the network again).

[0040] The reattachment method (375) comprises UE 202 sending an attachment request (380) to AN 204. The attachment request includes the SM-NSSAI, the UE Temp ID, and the MM parameters. AN 204 forwards the attachment request to AMF 218. The slice-specific authorization step (350) and, optionally, the UP connection step configuration (360) described above can be performed. AMF 218 can then send an attachment response (390) to UE 202 via AN 204. The attachment response includes the SM-NSSAI, the UE Temp ID, and the MM parameters (possibly updated). Once UE 202 is attached (or reattached) to data network 208, UE can initiate a packet data unit (PDU) session with data network 208.

[0041] Session management states describe the UP connectivity for a PDU session between UE 202 and SMF 220. For an established PDU session, there can be at least two session management states for a PDU session: an active state (e.g., Session-ACTIVE) and an idle state (e.g., Session-IDLE). In this description, “SessionACTIVE” can be used to denote an active state and “SessionIDLE” is used to denote an idle state. Because the PDU session status is related to the user’s data transmission (UL and DL) activities, the session state can alternatively be called the session connection state. Petition 870250082301, dated 12 / 09 / 2025, page 31 / 556 25 / 264

[0042] A session management state can be designed for each PDU session, respectively. The session management state can be maintained in UE 202 and SMF 220. AN 204 and UP functions may not be aware of the session management state. However, AN 204 and UP functions can maintain the session context of the established PDU session.

[0043] When a UE 202 is roaming (in a routed domestic roaming model), the PDU session can be served by two SMFs 220 in a chain: one for the visited public terrestrial mobile network (VPLMN) and another for the domestic public terrestrial mobile network (HPLMN). The session management state can be updated on the SMF 220 in the VPLMN, while the SMF 220 in the HPLMN can consider the PDU session as Session-ACTIVE.

[0044] When a UE PDU session has no UL or DL ​​activity for a given period, that session state may be changed to Session-IDLE. The UE may resume the PDU session(s) after a certain period of time by sending an Access Stratum (AS) message to AN 204 to activate the Data Radio Bearer (DRB). Alternatively, the UE may resume the PDU session(s) after a certain period of time by sending a Non-Access Stratum (NAS) message to the SMF to notify the session activation request. For example, a user is browsing a website. The user may not have any data transmission while viewing downloaded pages or downloaded video. The UE may again download new data for the same session after reading or viewing the downloaded content. In this example, if a time period expires while the user is viewing the downloaded content, the PDU session may be changed to Session-IDLE.When the user starts downloading more data, the PDU session is then changed to Session-ACTIVE.

[0045] In a PDU session request procedure and Petition 870250082301, dated 12 / 09 / 2025, page 32 / 556 26 / 264 combined attachment, a UE can send a request for a new session in an attachment request message. However, if the UE has no UL or DL ​​packet transmission after a period of time, the session state may change from Session-ACTIVE to Session-IDLE. Thus, by allowing a session to have both an active and an idle state, a UE can set up and maintain a new session for “future use” (or near-future use) even if the UE has no UL or DL ​​packet transmission for a period of time after the new session is set up. Without the Session-IDLE state, the session may have been prematurely released.

[0046] The session state attribute can allow CN 206 to efficiently handle PDU sessions from various applications. UE 202 can trigger a session connection state transition on CN 206, send an AS message to AN 204 to change the state of a DRB (between an active or suspended state); AN 204 can then inform SMF 220 of the UE request to activate or deactivate a PDU session on CN 206. Alternatively, UE 202 can trigger a session connection state transition on CN 206 by sending a NAS message to CN 206; then CN activates session management procedures on CN and informs AN 204 to allocate radio resources to the PDU session.The session connection state attribute can also enable quick reconnection on CN 206 when a session is resumed, reduce signaling overhead on the CP when a session or radio resource control (RRC) is resumed, utilize network function utilization resources when PDU sessions are idle for an extended period, and prevent RRC signaling in relation to session state changes on CN 206. In one embodiment, UE 202 is unaware of the session state on CN 206. In another embodiment, UE 202 is aware of the session connection state.

[0047] Figure 4 illustrates, in a state model diagram, Petition 870250082301, dated 12 / 09 / 2025, page 33 / 556 27 / 264 is an example of a Session-IDLE 400 state model. The Session-IDLE 400 state model shows how a Session-IDLE state can be represented in the CP (as a session state) and UP (as a session context) for UE 202, AN 204, SF 220, and UPF 212. When a PDU session is in the Session-IDLE state, there may be no dedicated UP connection to the PDU session existing between UE 202 and the UPF 212 function terminating with NG3. UE 202 may maintain the session context without any RAN resources enabled corresponding to the PDU session. In this example, AN does not maintain any radio resource context corresponding to the PDU session. If the PDU session is served by only one UPF 212 (that is, if only UPF A is present for UPF 212 in Figure 4), then the session context can be maintained in UPF A without information related to AN 204 of NG3.If the PDU session is served by two UPFs 212 in a chain (i.e., if only UPF A and UPF B are present in UPF 212 in Figure 4), then the session context can be maintained in both UPF A and UPF B. The UPF terminating NG3 may not maintain information related to AN 204. Both UPF A and UPF B can maintain information related to the NG9 tunnel. If the PDU session is a multi-homing PDU session (i.e., UPF A, UPF B, and UPF C are present as shown in Figure 4), the session context on the branch point UPF (i.e., UPF A) does not hold information related to AN 204. In this multi-homing PDU session, the branch point UPF A can hold information related to the NG9 tunnel for both UPF B and UPF C. UPF B and UPF C can hold information related to the NG9 tunnel towards the branch point UPF A.

[0048] UE 202 and SMF 220 may be in the SessionIDLE state when the data connection (i.e., NG3) dedicated to the given PDU session is not established between UE 202 and UPF 212. A NAS message (e.g., a Service Request) Petition 870250082301, dated 12 / 09 / 2025, p. 34 / 556 28 / 264 including the PDU session identifier (ID) data can initiate a transition from Session-IDLE to Session-ACTIVE. When a PDU session is in the Session-IDLE state, the session context on the UE 202 and SMF 220 may not be synchronized (i.e., the UE 202 and the network may have different sets of QoS flows enabled (e.g., for Guaranteed Bit Rate (GBR) QoS flows)). During the transition from SessionIDLE to Session-ACTIVE, the UE 202 may include QoS flow statuses indicating each QoS flow status (i.e., enabled or disabled) of the PDU session in the NAS message (e.g., Service Request), the set of flows of QoS enabled is synchronized between UE 202 and SMF 220.

[0049] Figure 5 illustrates, in a component diagram, an example of a Session-ACTIVE 500 state model. The Session-ACTIVE 500 state model shows how a Session-ACTIVE state can be represented in the CP (as a session state) and in the UP (as a session context) for the UE 202, AN 204, SF 220, and UPF 212. A PDU session can be in the Session-ACTIVE state when the data connection (i.e., NG3) dedicated to the given PDU session is established between the UE 202 and the UPF 214. In the Session-ACTIVE state, the UL / DL data belonging to the PDU session can be directly sent between the UE 202 and the network. The UE 202 can maintain a session context with RAN-enabled resources corresponding to the PDU session. AN 204 can maintain a session context and reserve RAN resources (for GBR QoS flow, if present) corresponding to the PDU session.In a PDU session served by only one UPF (i.e., only UPF A), the session context can be maintained in UPF A with information related to AN 204 of NG3. If the PDU session is served by two UPFs in a chain (i.e., only UPF A and UPF B), the session context can be maintained in both UPF A and UPF B. The UPF terminating NG3 can maintain information related to NG3. Both UPF A and UPF B can maintain information related to the NG9 tunnel. If a. Petition 870250082301, dated 12 / 09 / 2025, p. 35 / 556 29 / 264 PDU session: For a multihoming PDU session (i.e., UPF A, UPF B, and UPF C), the session context on the branch point UPF (i.e., UPF A) can maintain information related to AN 204. Branch point UPF A can maintain information related to the NG9 tunnel for both UPF A and UPF B. UPF A and UPF B can maintain information related to the NG9 tunnel towards branch point UPF A.

[0050] The AN 204 can be configured with a Session Idle Timer by the SMF 220 when a PDU session is established or activated. If, during the duration of the Session Idle Timer, no UL / DL data is detected in the PDU session on the AN 204, the AN 204 may initiate a session connection state transition procedure. The session connection state on the UE 202 and SMF 220 may enter Session-IDLE for the given PDU session.

[0051] AN 202 and SMF 220 can also initiate the PDU session deactivation procedure due to certain causes. For example, an O&M intervention, an unspecified failure, etc. When a PDU session is in the Session-ACTIVE state, during handover procedures, AN 204 can send AMF 218 the PDU session ID in a Handover Required message. Based on the PDU session ID, AMF 218 can notify the corresponding SMF 220 to execute the handover procedure.

[0052] The following session management (SM) parameters are used in this disclosure: Session-State, ActivateSession-when-RRC-Resumed, Session-Activity-Timeout, SMAction-for-Idle, and Keep-UE-Context-For-All.

[0053] The Session-State parameter can be used in a UE PDU session context of AN 204, SMF 220, UPF 212, UDM 216, and PCF 222. The Session-State parameter can have two values: Session-ACTIVE and Session-IDLE. Petition 870250082301, dated 12 / 09 / 2025, p. 36 / 556 30 / 264

[0054] The parameter, Activate-Session-when-RRC-Resumed, can be used to indicate whether a PDU session is in the Session-ACTIVE state when an RRC is resumed. This parameter can have two values: Yes and No. The parameter can be configured by PCF 222. PCF 222 can send this parameter to SMF 220. Then, SMF 220 can send this parameter to AN 204 and / or UE 202 during a session establishment procedure.

[0055] The parameter, Session-Activity-Timeout, can be a timer parameter in AN 204, configured by PCF 222 for individual PDU sessions. The parameter can be used to monitor activities in the UL and DL of a PDU session. If UE 202 does not have UL or DL ​​packets longer than the Session-Activity-Timeout parameter, then AN 204 can inform SMF 220. SMF 220 can then release this PDU session or change the state of a session from Session-ACTIVE to SessionIDLE, depending on the session management (SM) policy configured by PCF 222.

[0056] The parameter, SM-Action-for-Idle-Session, is an SM policy parameter configured by PCF 222. PCF 222 can send this parameter to SMF 220 during a session establishment procedure. The SM-Action-for-IdleSession parameter can have two values: Keep-Idle-Session and Release-Idle-Session. If the value is set to Keep-Idle-Session, SMF 220 can change the PDU session status from SessionACTIVE to Session-IDLE. If the value is set to Release-Idle-Session, SMF 220 can release the idle PDU session.

[0057] The parameter, Keep-UE-Context-For-Idle-Sessions, can be in the UE context of SMF 220 and UPF 222, as configured by PCF 222. This parameter can be used to indicate whether the UE 202 context can be maintained in SMF 220 and UPF 222 when all PDU sessions of the same UE 202 that are served by SMF 220 and UPF 222 are in the Session-IDLE state. The parameter Petition 870250082301, dated 12 / 09 / 2025, p. 37 / 556 31 / 264 Keep-UE-Context-For-Idle-Sessions can have two values: Keep and Can-Be-Released. If the Keep-UE-Context-For-Idle-Sessions parameter is set to Keep, then SMF 220 and UPF 222 can maintain the UE context regardless of the session state. If the Keep-UE-Context-For-Idle-Sessions parameter is set to Can-Be-Released, then at least one of the following can be applied: • UPF 212 and SMF 220 can maintain a complete EU context if their EU context has at least one active session. However, some information in the EU context may be released, such as NG3 connection information, including the NG3 Tunnel Endpoint Identifier and the AN 204 IP address. • UPF 212 and SMF 220 may or may not maintain the EU context if all sessions they serve are in an idle state. • When a UPF 212 releases the EU context of an EU 202 having all idle sessions, the UPF 212 can transfer its complete EU context to the SMF 220. Additionally, the UPF 220 can transfer the billing information from the EU context to the PCF 222.

[0058] Figure 6A illustrates, in a state diagram, an example of a 600A session management state model in a UE 202. The 600A session management state model shows a Session-IDLE state 610 and a Session-ACTIVE state 620. An active session (i.e., a session that is in the Session-ACTIVE state 620) can be transferred to the Session-IDLE state 610 after a request by UE 202 or a request by AN 204. Such requests may include an RRC connection reconfiguration to disable RAN resources for the PDU session, and an RRC connection release. An idle session (i.e., a session that is in the Session-IDLE state 610) can be transferred to the Session-ACTIVE state 620 after a request by UE 202 (data originating from mobile devices). Petition 870250082301, dated 12 / 09 / 2025, page 38 / 556 32 / 264 (MO) ) or a request via UPF 212 (mobile-terminated data (MT)). Such requests may include an RRC connection reconfiguration to enable RAN capabilities for the PDU session.

[0059] Figure 6B illustrates, in a state diagram, an example of a 600B session management state model in an SMF 220. The 600B session management state transition model shows the Session-IDLE state 610 and a Session-ACTIVE state 620. An active session (i.e., a session that is in the Session-ACTIVE state 610) can be transferred to the Session-IDLE state 620 after a request by UE 202 or a request by AN 204. Such requests may include a session deactivation request for the PDU session. An idle session (i.e., a session that is in the SessionIDLE state 620) can be transferred to the Session-ACTIVE state 610 after a request by UE 202 (MO data) or a request by UPF 212 (MT data). Such requests may include an RRC connection reconfiguration to enable RAN features for the PDU session.

[0060] Figure 6C illustrates, in a component diagram, an example of a 600C session management state model for multiple PDU sessions. A UE 202 can have multiple PDU sessions established using multiple SMFs 220 and UPFs 212. The NextGen system supports independent session connection state per PDU session (e.g., session A is in the Session-IDLE state, while session B and session C are in the Session-ACTIVE state. Session A and session B are served by SMF A, while session C is served by SMF B). When multiple PDU sessions are activated for a UE 202, AN 204 can be configured with individual Idle Session Timers by the SMF(s) 220 for each PDU session during the session activation procedure. When the UE 202 is in the CN-IDLE state, the session connection state of each session is Petition 870250082301, dated 12 / 09 / 2025, page 39 / 556 33 / 264 PDUs can be in Session-IDLE. When UE 202 requests to enter the CN-CONNECTED state from the CN-IDLE state (for example, a service request), UE 202 can also indicate that the PDU session(s) should be activated. The session connection state for the requested PDU session(s) can be changed to Session-ACTIVE on UE 202 and SMF 220, while other PDU sessions (if any) can remain in SessionIDLE. Whether or not UE 202 has an active PDU session, the NextGen system can support the activation of additional PDU sessions.

[0061] When a session is in a Session-IDLE state 610, an RRC can be in any state (e.g., RRC-CONNECTED, RRC-IDLE, RRC-INACTIVE). If all PDU sessions are in the Session-IDLE state, the RRC can be in any state, the mobility state will be MM-Registered, and the CN state will be CN-IDLE or CN-CONNECTED. DRB can be suspended. Therefore, there is no AS signaling for idle sessions. UE 202, AN 204, UPF 212, SMF 220, UDM 216, and PCF (222) can store relevant UE context, including tunnel information, for fast connection re-establishment. However, NG3 tunnel information may not be updated in the event of UE mobility or UPF 212 relocation. Tunnel maintenance procedures may not be executed. Additionally, an NG3 tunnel of idle sessions can be removed from the routing tables of AN 204 and UPF 212.Tunnel information will be updated when a session changes its Session-IDLE state to Session-ACTIVE. In an AN 204, UPF 212, SMF 220, UDM 216, and PCF 222 UE context, the Session-State parameter can be marked as Session-IDLE. NAS signaling is not required for idle sessions. In UPF 212, for idle sessions, TFTs may not be available in the UPF 212 packet classification function. Resources used for session data rate monitoring and billing (AMBR / MBR / GBR) may be released. Petition 870250082301, dated 12 / 09 / 2025, page 40 / 556 34 / 264

[0062] When a session is in a Session-ACTIVE 620 state, and an RRC is in an RRC-CONNECTED state, DRB / AS / NAS signaling is established. The mobility state is registered in MM and the CN state is CN-CONNECTED. Network functions that serve PDU sessions, including UE 202, AN 204, UPF 212, AMF 218, SMF 220, UDM 216, and PCF 222, have relevant UE context information. In the UE contexts of AN 204, UPF 212, SMF 220, UDM 216, and PCF 222, the Session-State parameter is marked as Session-ACTIVE. In UPF 212, the Traffic Flow Model (TFT) is available in the UPF 212 packet classification function. TFT is used to classify packets into Quality of Service (QoS) flows. Therefore, the more TFTs in use, the greater the complexity of the search in UPF 212. Thus, only TFTs from active sessions are searched for ingress packets in UPF 212.In AN 204 and UPF 212, features for monitoring and charging PDU session data rates (aggregate maximum bit rate (AMBR) / maximum bit rate (MBR) / guaranteed bit rate (GBR)) are in operation.

[0063] SMF 220 can change the state of a PDU session from Session-ACTIVE to Session-IDLE based on requests from UE 202 and AN 204, or based on its own decision. UE 202 and UPF 212 can inform SMF 220 about the presence of UE data so that SMF 220 can change the state of a session from Session-IDLE to Session-ACTIVE. It is possible to change the status of individual sessions or a group of sessions. SMF 220 informs UPF 212 so that UPF 212 must maintain or may optionally remove the UE context, depending on the SM policy for this PDU session configured by PCF 222.

[0064] When UE RRC 202 is in an RRC-CONNECTED state and AN 204 changes the RRC to RRC-IDLE or RRC-INACTIVE CONNECTED mode, the state of all UE 202 PDU sessions may be set to the Session-IDLE state. Petition 870250082301, dated 12 / 09 / 2025, p. 41 / 556 35 / 264

[0065] When an RRC connection is resumed, the CN state changes from CN-IDLE to CN-CONNECTED. For MO transmission, UE 202 can send an AS request to AN 204 to resume the RRC connection. This request can include the DRB identifiers (IDs) to be resumed. Alternatively, UE 202 can send a NAS request to SMF 220 to indicate which session should be resumed. It is possible to resume SM for some specific PDU sessions. For MT transmission, UPF 212 can send a UE context update request to SMF 220. SMF 220 interacts with AMF 218 to page UE 202 in order to activate the RRC connection.

[0066] To support individual session (de)activation, UE 202 and AN 204 can initiate a procedure to suspend or resume DRBs. If a DRB is suspended, the session state on CN 206 can be changed to Session-IDLE. If a DRB is resumed, the session state on CN 206 can be changed to Session-ACTIVE.

[0067] The session management procedures for session establishment, session release, session modification, RRC state transition, and session state transition are described below.

[0068] Figure 7 illustrates, in a message flowchart, an example of a session establishment procedure (700), according to an embodiment of the present invention. The steps for the session establishment procedure (700) can be performed by various components of the non-roaming architecture 210 to establish a session between UE 202 and DN 208. PCF 222 may have an SM policy that includes information regarding specific network slice preferred logical UL and DL paths between AN 204 and UPF 212.

[0069] Method (700) involves the EU sending a new Petition 870250082301, dated 12 / 09 / 2025, p. 42 / 556 36 / 264 NAS session request message (705) that includes an SMNSSAI, a temporary UE ID and a UE-generated session ID, service type, and a Domain Name Network (DNN) to AMF 218 via NA 204. Note that when the PDU session is created in conjunction with an initial UE attachment or re-attachment procedure for some specific network slices, the UE may provide the UE-generated session ID along with the initial attachment or re-attachment request. AMF 218 uses the SM-NSSAI to select an SMF 220 and forward the session request message to the selected SMF 220 (710), along with an IP address of the serving AN. AMF 218 may store the ID of the selected SMF 220. When SMF 220 receives the request from AMF 218, SMF 220 can store the ID of AMF 218 that serves UE 202.SMF 220 can access user subscription information in UDM 216 for service authorization (715) (i.e., SMF-UDM service authorization messages). If the service is not authorized, then SMF 220 can send an appropriate session creation reply message (760) sent to UE 202 via AMF 218. The session creation reply may include a session denial code.

[0070] If the service is authorized (715), then the configuration of the UP (360) connections for a specific UE pattern or slice type can be performed. The configuration of the UP (360) connections can include SMF 220 obtaining the UE policies from PCF 222 (720), including SM, QoS and billing policies (i.e., retrieving SMF-PCF UE policies (SM, QoS, billing)). SMF 220 can also allocate the IP address(es) for UE 202 if the PDU session is an IP-based session. The SM policy can include at least the following information: the preferred UPF(s) 212 to support mobile edge computing (MEC) applications; the Session-Activity-Timeout parameter; the Keep-UEContext-For-Idle-Sessions parameter; the parameter SM-Action-for-IdlePetition 870250082301, dated 12 / 09 / 2025, page 43 / 556 37 / 264 Session; and the parameter Activate-Session-when-RRC-Resumed.

[0071] Optionally, SMF 220 can subscribe to AMF 218 for EU mobility information (725), if mobility pattern-based session management optimization is performed and if SMF has not yet subscribed to AMF 218 for the information. Note that SMF-AMF EU mobility information subscription messages (725) can be a standalone procedure that can occur at any time before, after, or during session establishment. In this example, the SMF-AMF EU mobility information subscription is shown in the session establishment procedure.

[0072] Next, SMF 220 can send to the serving AN 204, via AMF 218, an AN resource configuration request message (730). The request can include the temporary UE ID, the session ID, the QoS profile, and the selected IP address of UPF 212. The request can also include the Session-Activity-Timeout parameter and the Activate-Session-when-RRC-Resumed parameter.

[0073] Optionally, if the session ID provided by UE 202 is included in the attachment request, AN 204 may perform admission control for the requested PDU session according to the QoS profile. If the PDU session is accepted, AN 204 may establish (i.e., configure) a DRB (735) according to the QoS profile. Note that for some services, although UE cannot request a new session during the attachment procedure, CN 206 may still establish the UP path, even if there is no DRB established between UE 202 and AN 204.

[0074] AN 204 can then send to SMF 220, via AMF 218, an AN resource configuration response message (740). AN 204 can store all UE-related information in a UE-specific context profile, including the Session-State parameter. SMF 220 can then select UPF 212 based on the preferred UPF policy(ies), Petition 870250082301, dated 12 / 09 / 2025, page 44 / 556 38 / 264 if available, and the current traffic load of UPFs 212. SMF 220 can send a UPF session configuration request message (745) to the selected UPF 212, which can include at least the temporary UE ID, the session ID, the IP address(es) of UE 202, the QoS and billing policies, the DNN, and the Keep-UE-Context-For-Idle-Sessions parameter. UPF 212 can store all UE-related information in a specific UE context, which can include the temporary UE ID, the session ID, the AN 204, the IP address(es) of UE 202, the QoS and billing policies, and other information. Note that the session ID can be omitted for some UE types, such as simple Internet of Things (IoT) devices, which access only one slice and only one PDU session per network slice. [007 5] Next, UPF 212 can send a UPF session configuration reply message (750) to SMF 220. SMF 220 can store all UE-related information in an SM UE context profile, including the SessionState parameter. SMF 220 can then send a session creation reply message (755) to AMF 218, which can include the temporary UE ID and session ID. AMF 218 can trigger mobility management procedures. SMF 220 can then send a NAS session creation reply message (760) to UE 202 via AMF 218. If the session request is accepted, the session creation reply can include the session ID, the assigned IP address(es), an optional QoS profile, and the session and service continuity (SSC) mode.The SM can store EU context information, including SM policy, QoS and billing policies, the assigned IP address(es), AMF ID, AN ID, UPF ID, NG3 tunnel information, and other parameters. Steps 755 and 760 can be combined. For example, SMF 220 can send a message containing two parts: one to AMF 218 and one to the... Petition 870250082301, dated 12 / 09 / 2025, p. 45 / 556 39 / 264 UE 202. After receiving the combined session creation response message, AMF 218 can detach the information for itself and forward the UE portion to UE 202. As mentioned above, if the session request is rejected, the session creation response may include an error code. This error code may be Unauthorized Service Request, Network Resource Interruption, Insufficient Credit for Billing, or another error code. Note that if UE 202 requests a new session in an initial attachment and re-attachment request, step (760) may be omitted. In this case, in the initial attachment and re-attachment procedures, AMF 218 may send an attachment response message that includes session management information. The SM information may include the session ID and QoS profile.

[0076] Optionally, SMF 220 can send UE session management information (i.e., via an SMF-UE context update procedure (765)) to UDM 216. Also optionally, AMF 218 can send UE mobility management-related information (i.e., via an AMF-UDM UE context update procedure (770)) to UDM 216. Optionally, SMF 220 and PCF 222 can execute an SMF-PCF session update procedure (775) where the actual PDU session parameters can be sent from SMF 220 to PCF 222. Note that AN 204 and UPF 212 can configure a tunnel if this tunnel does not already exist.

[0077] Figure 8 illustrates, in a message flowchart, an example of the SMF-AMF mobility information subscription procedure (725), according to a modality of the session establishment procedure (700). SMF 220 can send to AMF 218 (or AMF 218 can receive from SMF 220) a message requesting SMF-AMF UE mobility information (826). The message (826) can include one or more identifiers to identify UE 202 (such as UE ID). Petition 870250082301, dated 12 / 09 / 2025, p. 46 / 556 40 / 264 temporary, International Mobile Subscriber Identity (IMSI), GUTI), the mobility time window and the subscription type. The mobility time window indicates the time interval for the requested EU mobility information. The subscription type indicates whether the subscription is a one-time information retrieval or can use periodic information updates. SMF 220 can then receive from AMF 218 (or AMF 218 can send to SMF 220) an SMF-AMF EU mobility information update message (828). The message may include the identifiers of the set of ANs 204 that can potentially serve the EU in the specified mobility time window. AMF 218 can perform the mobility information update (828) upon receiving the request (826) and, if the request (826) indicates a periodic update, when the requested mobility information changes.AMF 218 can determine the ANs 204 set service according to EU mobility standard 202. Other steps can be added to the procedure (725).

[0078] Figure 9 illustrates, in a message flowchart, an example of the SMF-UDM UE context update procedure (765), according to a session establishment procedure embodiment (700). SMF 220 can send to UDM 216 (or UDM 216 can receive from SMF 220) a request message for an SMF-UDM UE context update (966). The message (966) can include identifiers to identify UE 202 (such as temporary ID, IMSI, GUTI) and the UE context or new values ​​of UE context parameters that have been changed. SMF 220 can then receive from UDM 216 (or UDM 216 can send to SMF 220) an SFM-UDM context update reply message (968) to confirm that the UE context has been updated in UDM 216. Other steps can be added to the procedure (765).

[0079] Figure 10 illustrates, in a message flowchart, an example of an AMF context update procedure. Petition 870250082301, dated 12 / 09 / 2025, page 47 / 556 41 / 264 UDM UE (770), in accordance with a session establishment procedure modality (700). AMF 218 may send to UDM 216 (or UDM 216 may receive from AMF 218) a context update request message (1072) from AMF-UDM UE to update the mobility management parameters for a UE 202. The message (1072) may include identifiers to identify the UE 202 (such as temporary UE ID, IMSI, GUTI) and the UE context or new values ​​of UE context parameters that have been changed. AMF 218 can then receive from UDM 216 (or UDM 216 can send to AMF 218) an AMF-UDM UE context update reply message (1074) to confirm that the mobility management parameters in the UE context have been updated in UDM 216. Other steps can be added to the procedure (770).

[0080] Figure 11 illustrates, in a message flowchart, an example of an SMFPCF session update procedure (775), according to an embodiment of the session establishment procedure (700). SMF 220 can send to PCF 222 (or PCF 222 can receive from SMF 220) a UE session update request message (1176) from SMF-PCF to update the session parameters for a UE 202. The message (1176) can include identifiers to identify UE 202 (such as temporary UE ID, IMSI, GUTI) and the UE context (session management, QoS parameters, billing information) or new UE context parameter values ​​that have been changed. SMF 220 can then receive from PCF 222 (or PCF 222 can send to SMF 220) an SMF-PCF session update reply message (1178) to confirm that UE 202 session management parameters have been updated in PCF 136.Other steps may include SMF-UPF disabling all session response messages to the procedure (775).

[0081] Figure 12 illustrates, in a flowchart, an example of a method for establishing a session (1200), according to Petition 870250082301, dated 12 / 09 / 2025, p. 48 / 556 42 / 264 the session establishment procedure (700). The method (1200) is performed by SMF 220. SMF 220 can be implemented as a session management function module on a server in CN 206. SMF 220 can be configured to receive a session request message (1210). The session request message can be from an AMF 218 that received the session request message from a UE 202. Once SMF 220 receives the session request message, SMF 220 can determine if UE 202 is authorized to request the service (1220). To perform this service authorization, SMF 220 can access the user subscription information in UDM 216. If the service is not authorized (1220), then SMF 220 can send an appropriate session creation response message (760) to UE 202 via AMF 218. As described above, the session creation response can include a session denial code.If the service is authorized (1220), and if a mobility pattern-based session management optimization is performed, and if SMF 220 has not yet subscribed to AMF for information, (1230), SMF 220 may subscribe to AMF 218 for EU mobility information (725), as described above. Note that, as described above, steps (1230) and (725) can be performed at any time before, during, or after method (2040).

[0082] SMF 220 can obtain EU policies from PCF 222 (720), as described above. Then, SMF 220 can send the resource configuration request message (730) to the serving AN 204 via AMF 218, as described above. SMF 220 can then receive the resource configuration reply message from AN 204 via AMF 218 (740), as described above. Then, SMF 220 can send a UP configuration request message to a selected UPF 212 (745), as described above. Then, SMF 220 can receive a configuration reply message. Petition 870250082301, dated 12 / 09 / 2025, page 49 / 556 43 / 264 session from UPF 212 (750), as described above. SMF 220 can then send a session creation reply message (755) to AMF 218, as described above. SMF 220 can then send a session creation reply message (760) to UE 202 via AMF 218, as described above.

[0083] Other steps can be added to the method (2040), including SMF 220 storing all UE-related information in an SM UE context profile, including the Session-State parameter. SMF 220 can also optionally send UE session management information to UDM 216 (765).

[0084] Figure 13 illustrates, in a message flowchart, an example of a session modification procedure (2060), according to an embodiment of the present invention. A PDU session modification procedure can be triggered by PCF 222, UE 202, and SMF 220. A first possible trigger for session modification occurs when PCF 222 sends SMF 220 a PCF-SMF session modification request (1310a). The request may include the temporary UE ID, the session ID, and the new billing / SM / QoS policy parameters. A second possible trigger for session modification occurs when UE 202 sends SMF 220, via AMF 218, a UE-SMF session modification request for an active session (1310b). The request may include the SM-NSSAI, the temporary EU ID, the session ID, a list of parameters to be changed and their new values, and an EU time zone.A third possible trigger for session modification occurs when SMF 220 creates an SMF session modification request (1310c) based on current EU policies and other factors (e.g., load changes in UPF 212 and AN 204).

[0085] If the first and second possible triggers are responsible for the session modification request, the SMF Petition 870250082301, dated 12 / 09 / 2025, page 50 / 556 44 / 264 220 can check session modification requests (1320). If the request comes from PCF 222 for UE policy updates (1310a), then the new policy update can be stored in local memory of SMF 220. SMF 220 can create a session modification request for AN 204 and UPF 212 based on the new policy parameters. If the request comes from UE 202 (e.g., for new QoS parameters (higher MBR or higher GBR)) (1310b), SMF 220 can check the request against the current UE policies. If the UE request (1310b) is allowed, then SMF 220 can create a session modification request for AN 204 and UPF 212 based on the UE request. If the EU request (1310b) is not allowed, then SMF 220 can send a cause code to the EU (1390b) and the other steps in the procedure (1300) can be disregarded.

[0086] UE 202 may request a session modification that may be outside the policies stored in SMF 220. For example, UE 202 may request an additional GBR stream for a current PDU session that does not have GBR streams. If UE 202 requests an additional GBR stream, then SMF 220 and PCF 222 may execute a UE policy retrieval procedure. SMF 220 may send PCF 222 an SMF-PCF UE policy request message (1330), which may include the policy required for the additional PDU stream that UE requested. PCF 222 may return to SMF 220 an SMFPCF UE policy response message (1335), which may include the UE policy.

[0087] Next, SMF 220 can send an SMF-AN session modification request message (1340) to AN 204 via AMF 218. The request can include new SM parameters and / or new QoS parameters. Optionally, AN 204 can then perform admission control (1350) if a new GBR flow is requested or an existing GBR flow is modified. If the QoS parameter changes are accepted, Petition 870250082301, dated 12 / 09 / 2025, page 51 / 556 45 / 264 AN 204 can optionally perform a session modification procedure with UE 202. AN 204 can send UE 202 a session modification request message (1360). The request can include new QoS, SM, or policy parameters. After applying new QoS, SM, or policy parameters, UE 202 can send AN 204 a session modification response message (1365).

[0088] Next, AN 204 can send to SMF 220, via AMF 218, an SMF-AN session modification response message (1370), which may include an acknowledgment or a cause code. If the SMF-AN session modification response message includes a cause code, steps (1380) and (1385) can be disregarded. Otherwise, SMF 220 and UPF 212 can execute an SMF-UPF session modification procedure. SMF 220 can send to UPF 212 an SMF-UPF session modification request message (1380), which may include the temporary UE ID, session ID, and new PDU session parameters. UPF 212 can receive new session parameters and check if the new parameters can be supported. If the new parameters can be supported, UPF 212 can reconfigure its resources to support the PDU session.UPF 212 can then send SMF 220 an SMF-UPF session modification reply message (1385), which may include an acknowledgment or a cause code. SMF 220 can then send a reply to the original request. If the session modification request came from PCF 222, then SMF 220 can send PCF 222 a PCF-SMF session modification reply message (1390a), which may include an acknowledgment or a cause code. If the session modification request came from UE 202 (1310b) or SMF 220 (1310c), SMF 220 can send PCF 222 a PCF-SMF session modification reply message (1390a) containing new session parameters. If the session modification request came from UE 202 (1310b),... Petition 870250082301, dated 12 / 09 / 2025, page 52 / 556 46 / 264 then SMF 220 can send UE 202 a UE-SMF session modification reply message (1390b), which may include an acknowledgment or a cause code. Optionally, SMF 220 can execute a UE context update procedure (765) with UDM 216.

[0089] Figure 14 illustrates, in a flowchart, an example of a method for modifying a session (1400), according to the session modification procedure (1300). The method (1400) is executed by SMF 220. SMF 220 can be configured to determine that a session modification should be executed (1410). This determination (1410) may be due to SMF 220 receiving a PCF-SMF session modification request message from PCF 222. Alternatively, this determination (1410) may be due to SMF 220 receiving a UE-SMF session modification request message from UE 202. Alternatively, this determination (1410) may be due to SMF 220 generating an SFM session modification request message based on current UE policies and other factors (e.g., load changes in UPF 212 and AN 204).If the determination (1410) was made due to requests from PCF 222 or UE 202 (1420), then SMF 220 is configured to check the received session modification requests (1320), as described above. SMF 220 can then send the SMF-AN session modification request message to AN 204 (1340), via AMF 218, as described above. Next, SMF 220 can receive the SMF-AN session modification response message from AN 204 (1370), via AMF 218, as described above. Then, SMF 220 can send the SMF-UPF session modification request message (1380) to UPF 212, as described above. SMF 220 can then receive the SMF-UPF session modification response message (1385) from UPF 212, as described above. If the session modification was due to a... Petition 870250082301, dated 12 / 09 / 2025, page 53 / 556 47 / 264 request from SMF 220 (1430), then SMF 220 can send to PCF 222 a PCF-SMF session modification reply message (1390a), as described above. If the session modification was due to a request from UE 202 (1440), then SMF 220 can send to PCF 222 a PCF-SMF session modification reply message (1390a), and then SMF 220 can send to UE 202 a UE-SMF session modification reply message (1390b), as described above.

[0090] Other steps can be added to method (2080), including sending a PCF-SMF session modification reply message to PCF 222 if PCF 222 sent the original session modification request to SMF 220. Alternatively, SMF 220 can send an SMF session modification reply message to UE 202 if UE 202 sent the original session modification request to SMF 220. Additionally, SMF 23 can optionally send an SMF-PCF UE policy request message to UPF 212 (1330), and receive an SMFPCF UE policy reply message from UPF 212 (1335), as described above.

[0091] Figure 15 illustrates, in a message flowchart, an example of a session release procedure (1500), according to an embodiment of the present invention. The PDU session release procedure (1500) can be triggered by UE 202, AN 204, UPF 212, and SMF 220. A first possible trigger for the PDU session release occurs when UE 202 sends a UE Session Release Request message (1510a) to SMF 220. The message may include the SM-NSSAI, the temporary UE ID, and the session ID. A second possible trigger for the PDU session release occurs when AN 204 sends an AN Session Release Request message (1510b) to SMF 220. AN 204 may report one of: a congestion condition for some PDU sessions, no traffic activity for an extended period, and / or other conditions. Petition 870250082301, dated 12 / 09 / 2025, page 54 / 556 48 / 264 A third possible trigger for PDU session release occurs when UPF 212 sends a UPF Session Release Request message (1510c) to SMF 220. UPF 212 may report at least one congestion condition for some PDU sessions, a billing policy violation (i.e., time-based, data volume-based, etc.), and / or other conditions. A fourth possible trigger for PDU session release occurs when SMF 220 decides to release a PDU session based on its own logic (1510d), or by receiving information from UE 202, AN 204, and / or UPF 212. Once SMF 220 has decided to release a session, there are two options for a session release procedure for UE 202 and AN 204.

[0092] In the first session release procedure option, SMF 220 can send UE 202, via AMF 218, an SMF-UE Session Release Request message (1520a), which can include the temporary UE ID, the session ID, and a cause code. The cause code value can indicate the origin of the session release request, such as: “Session Release by UE (corresponding to step 1510a); “Session Release by AN (corresponding to step 1510b); “Session Release by UPF (corresponding to step 1510c); and “Session Release by SMF (corresponding to step 1510d). Then, UE 202 can release its DRB resources and the PDU session context. UE 202 can send to SMF 220, via AMF 218, an SMF-UE session release reply message (1530a) to confirm the release of AN 204 resource for the released PDU session.Next, SMF 220 can send AN 204, via AMF 218, an SMF-AN Session Release Request message (1540), which may include the temporary UE ID and the session ID. Then, AN 204 can remove the UE PDU context and release DRB resources. AN 204 can send a release response message to SMF 220 via AMF 218. Petition 870250082301, dated 12 / 09 / 2025, p. 55 / 556 49 / 264 of SMF-AN session (1550) to confirm the release of AN 204 resource for the released PDU session.

[0093] In the second session release procedure option, SMF 220 can send AN 204, via AMF 218, an SMF-AN Session Release Request message (1540), which can include the temporary UE ID, the session ID, and a cause code. The cause code value can indicate the origin of the session release request, such as: “Session Release by UE (corresponding to step 1510a); “Session Release by AN (corresponding to step 1510b); “Session Release by UPF (corresponding to step 1510c); and “Session Release by SMF (corresponding to step 1510d). Then, AN 204 can send an AN-UE Session Release Request message (1520b) to UE 202. The message indicates the DRB to be released (which is being used to serve the PDU session) and a cause code. UE 202 can then release its DRB resources and the PDU session context.UE 202 can send an AN-UE session release reply message (1530b) to AN 204. Then, AN 204 can remove the UE PDU context and release DRB resources. AN 204 can send an SMF-AN session release reply message (1550) to SMF 220 to confirm the release of AN resources for the released PDU session.

[0094] Next, SMF 220 and UPF(s) 212 can execute an SMF-UPF session release procedure. SMF 220 can send UPF 212 an SMF-UPF Session Release Request message (1560a). The message can include the temporary UE ID and session ID. UPF 212 can then remove the UE PDU session context and release resources serving the PDU session. UPF 212 can send SMF 212 an SMF-UPF Session Release Response message (1560b). Note that UPF 212 can send billing information to PCF 222 via SMF 220. Optionally, SMF Petition 870250082301, dated 12 / 09 / 2025, page 56 / 556 50 / 264 220 and UDM 216 can execute an SMF-UDM UE context update procedure (1570), in which UDM 216 can remove the UE PDU session information. Then, SMF 220 and PCF 222 can execute an SMF-PCF UE context update procedure (1580). SMF can forward billing information to PCF 222. PCF 222 can remove the PDU session information from the released PDU session.

[0095] Figure 16 illustrates, in a flowchart, an example of a session release method (1600), according to the session release procedure (1500). The method (1600) is performed by SMF 220. SMF 220 can be configured to determine the release of a session (1610), as described above with reference to Figure 15. Once the determination (1610) is made, SMF 220 can send the SMF-UE release request message (1520a) to UE 202, via AMF 218, as described above. Then, SMF 220 can receive the SMF-UE release response message (1530a) from UE 202, via AMF 218, as described above. Next, SMF 220 can send the SMF-AN Session Release Request message (1540) to AN 204, via AMF 218, as described above. Then, SMF 220 can receive the SMF-AN Session Release reply message (1550) from AN, via AMF 218, as described above.Next, SMF 220 can send the SMF-UPF Session Release Request message (1560a) to UPF 212, as described above. Then, SMF 220 can receive the SMFUPF Session Release response (1560b) from UPF 212, as described above. Then, SMF can execute an SMF-PCF UE context update procedure (1570) with PCF 222, as described above. Other steps can be added to the method (1600), including SMF 220 and UDM 216 executing an optional SMF-UDM UE context update procedure (765), as described above. Petition 870250082301, dated 12 / 09 / 2025, page 57 / 556 51 / 264

[0096] Figure 17 illustrates, in a flowchart, another example of a session release method (1700), according to the session release procedure (1500). The method (1700) is executed by SMF 220. SMF 220 can be configured to determine the release of a session (1610). The determination (1610) can be based on receiving a Session Release Request message from UE 202. Alternatively, the determination (1610) can also be based on receiving a Session Release Request message from AN 204. Alternatively, the determination (1610) can also be based on receiving a Session Release Request message from UPF 212. Alternatively, the determination (1610) can also be based on the logic of SMF 220. Once the determination is made, SMF 220 can send the SMF-AN Session Release Request message (1540) to AN 204, via AMF 218, as described above.Next, SMF 220 can receive the SMF-AN (1550) session release response message from the AN, via AMF 218, as described above. Note that before SMF receives the SMF-AN (1550) session release response message from the AN, the AN would have sent an AN-UE Session Release Request to the UE and received an AN-UE session release response from the UE, as described above. Then, SMF 220 can send the SMF-UPF (1560a) Session Release Request message to UPF 212, as described above. Then, SMF 220 can receive the SMF-UPF (1560b) session release response from UPF 212, as described above. Next, the SMF can perform an SMF-PCF UE (1570) context update procedure with PCF 222, as described above.Other steps can be added to method (1700), including SMF 220 and UDM 216 executing an optional UE SMF-UDM context update procedure (765), as described above. Petition 870250082301, dated 12 / 09 / 2025, page 58 / 556 52 / 264

[0097] Figure 18 illustrates, in a message flowchart, an example of a PDU session connection state transition procedure (1800), according to an embodiment of the present invention. UE 202 may have its own logic to determine whether the session connection state of a session can be changed. AN 204 may monitor the UL / DL activities of the PDU session to request SMF 220 to change the session connection state to Session-IDLE. The procedure (1800) may be triggered by UE 202 or AN 204. A first possible trigger for the PDU session connection state transition procedure occurs when UE 202 sends SMF 220 a session connection state transition request (1810a) (Session-ACTIVE or Session-IDLE). Message (1810a) may include the temporary UE ID, SM-NSSAI(s), session ID(s) and new session connection state.A special Session ID value (e.g., wildcard) can be used to represent that all PDU sessions being served by the same SM indicated in the SM-NSSAI are in the idle state. Another possible trigger for the PDU session connection state transition procedure occurs when AN 204 monitors PDU session activities of all PDU sessions and AN 204 does not detect any UL and DL packets from a session after a Session Idle Timer set by SMF 220 during a session establishment procedure (700). AN 204 sends SMF 220 a Session-IDLE state transition request (1810b), which requests the setting of the state of a single PDU session, or multiple PDU sessions, to the Session-IDLE state. The message can include the temporary UE ID, the SM-NSSAI(s), the session ID(s), and the AN ID.A special session ID value (e.g., wildcard) can be used to represent that all PDU sessions being served by the same SM indicated in the SMNSSAI are in an idle state.

[0098] The parameter for the session connection state of Petition 870250082301, dated 12 / 09 / 2025, page 59 / 556 53 / 264 SM UE context is set to the new state as requested (1820). Then, SMF 220 can notify AN 204 of the session connection state transition (1830a). The notification can include the UE ID, session ID, and other information. If the session connection state is changed to Session-IDLE, SMF 220 can request that AN 202 release PDU session information, including NG3 tunnel information. AN 204 can also release radio resources serving the PDU session. If the session connection state is changed to Session-ACTIVE, SMF 220 can send to the PDU session context, including NG3 tunnel information and the QoS profile. AN 204 can then prepare radio resources to serve the PDU session according to the QoS profile. If the QoS flows require admission control, AN 204 can perform admission control.Next, AN 204 can send a session connection state transition response (1830b) to SMF 220. The response can be an acknowledgment or an error code (cause). If the response is a cause code, the remaining steps in the procedure will not be executed.

[0099] If the response (1830b) is not a cause code, then SMF 220 can request that UPF 212 perform a “UE Context Update (1840)” service. SMF 220 can request UPF 212 to release NG3 tunnel information from the UE context on UPF 212 if the session connection state is changed to Session-IDLE. In this request, the tunnel endpoint ID of AN 204 can be set to NULL. If the session connection state is changed to SessionACTIVE, SMF can request that UPF 212 add the IP address of AN 204 to the NG3 tunnel information. Then, SMF 220 can request AMF 218 to perform a “UE Context Update (1850)” service. The session connection state in the context of AMF 218 can be configured to the new session connection state. The notification may include the Petition 870250082301, dated 12 / 09 / 2025, p. 60 / 556 54 / 264 EU ID, session ID, and the new requested session connection state. AMF 218 can store the session connection state of the session in its EU context.

[00100] Next, SMF 220 can notify UE 202 of the new session connection status (1860a). The notification may include the session ID, the new session connection state, and a cause code if SMF 220 receives a cause code from AN 204. UE 202 may then send a Session-IDLE state transition response message (1860b) to SMF 220. SMF 220 then requests PCF 222 to perform a “UE Context Update” service (1870). The new session connection state may be sent to PCF 222. The service request from SMF 220 may include the UE ID, session ID, and the new session connection state. The request (1870) may be the SMF-PCF UE context update procedure (1580) as described above.

[00101] Figure 19 illustrates, in a flowchart, an example of a method for performing a state transition (1900), according to the PDU session connection state transition procedure (1800). The method (1900) can be executed by SMF 220. SMF 220 can be configured to receive a session state transition request (1910). The request can be from UE 202 or from AN 204. Then, SMF 220 can update the session connection state parameter of the SM UE context to the requested connection state (1820). Then, SMF 220 can send a session connection state transition request message to AN 204 (1830a). Then, SMF 220 can receive a session connection state transition response message from AN 204 (1830b). Next, SMF 220 can send a service request for “EU Context Update” to UPF 212 (1840).Next, SMF 220 can send a service request for “EU Context Update” to AMF 218 (1850). Then, a. Petition 870250082301, dated 12 / 09 / 2025, page 61 / 556 55 / 264 SMF 220 can send a session connection state transition notification to UE 202 (1860a). Then, SMF 220 can receive a session connection state transition response from UE 202 (1860b). Then, SMF 220 can send a service request for “UE Context Update” to PCF 222 (1870). Other steps can be added to the PDU (1800) session connection state transition procedure.

[00102] Figure 20 illustrates, in a message flowchart, an example of an RRC suspension procedure (2000), according to an embodiment of the present invention. A result of this procedure (2000) may be the transition of a PDU session from an active state to the PDU Session-IDLE state. UE 202 may have its own logic to determine whether the RRC state can be suspended to save power, but without releasing the current session(s). In this scenario, the current session(s) state can be set to Session-IDLE on AN 204, UPF 212, SMF 220, PCF 222, and optionally UDM 216. UE 202 can have multiple PDU sessions, where each session can be served by a single UPF 212 or multiple UPF 212s. UE can have access to multiple network slices, where each slice can have a separate SMF 220 to serve UE 202. The RRC suspension procedure (2100) can be triggered by UE 202 or AN 204.A first possible trigger for the Session-IDLE state transition occurs when UE 202 sends AN 204 a UE-AN RRC suspension request message (2010a). A second possible trigger for the Session-IDLE state transition occurs when AN 204 detects no activity on the UL and DL (2010b). After a UE-ActivityTimeout timer expires, AN 204 can suspend the RRC connection.

[00103] Next, AN 204 and AMF 218 can execute an AN-AMF UE CN status update procedure (2020). AN 204 can send a request message to AMF 218. Petition 870250082301, dated 12 / 09 / 2025, p. 62 / 556 56 / 264 AN-AMF UE CN-IDLE status transition (2020a), which may include the temporary UE ID, the new CN-IDLE status of UE 202, and a cause code “UE Requests RRC Suspension” (corresponding to step 2010a) or “All Sessions Idle” or “No Data Activity” (corresponding to step 2010b). AMF 218 can then change the status of UE 202 to CN-IDLE and stop AMF 218 procedures with UE 202. AN can then send UE 202 an AN-AMF UE CN-IDLE status transition response message (2020b).

[00104] Next, AN 204 and UE 202 can perform a UE-AN RRC suspension procedure (2030). AN 204 can send UE 202 a UE-AN RRC suspension response message (2030a), which can include a cause code and an RRC resumption ID. The cause code value can be the same as the cause code in step (2020a). AN 204 can then disable all AS signaling procedures and mark all DRBs in a suspended state. Then, UE 202 can perform a UE RRC suspension procedure (2030b).

[00105] Next, AMF 218 and SMF(s) 220 can execute an AMF-SMF UE CN-IDLE status update procedure (2040). AMF 218 can send to SMF(s) 220 an AMF-SMF UE CN-IDLE status transition request message (2040a), which can contain the temporary UE ID, the new CN-IDLE status of UE 202, and the optional cause code as in step (2020a). Then, SMF(s) 220 can send to AMF 218 an AMF-SMF UE CN-IDLE status transition response message (2040b). Upon recognizing the request message for transition from UE-IDLE CN status received from AMF 218, SMF 220 can implicitly assume that AN 204 has placed all UE 202 PDU sessions in the Session-IDLE state.

[00106] Next, SMF 220 can execute an SMF procedure to disable all sessions (2050) to put the PDU sessions into the Session-IDLE state on UPF(s) 220. SMF 220 Petition 870250082301, dated 12 / 09 / 2025, p. 63 / 55657 / 264 can send to UPF(s) 212 that serves UE PDU sessions a request message to disable all SMF-UPF sessions (2050a), which may indicate that the PDU session status should be changed to the Session-IDLE state. The message (2050a) includes the temporary UE ID and the session ID(s) (or a wildcard parameter). The wildcard parameter (which may be a special value for a session ID) may indicate that the state of the PDU sessions being served by UPF 212 should be set to Session-IDLE. Then, UPF 212 can set the Session-State field of the UE PDU session context to SessionIDLE. UPF 212 can follow the SM policy in the KeepUE-Context-For-Idle-Sessions parameter. If in this UPF 212, UE 202 does not have another active PDU session (served by other RATs), and if the value of the Keep-UE-Context-For-Idle-Sessions parameter is set to Keep, then UPF 212 (and SMF 220) can maintain the UE context regardless of the session state.If in this UPF 212, UE 202 does not have another active PDU session (served by other RATs), and if the value of the Keep-UE-Context-ForIdle-Sessions parameter is set to Can-Be-Released, then UPF 212 can maintain the complete UE context, depending on the storage resource.

[00107] Next, UPF 212 can send a response message to SMF 220 disabling all SMF-UPF sessions (2050b). If the UE context is released, then UPF 212 can send the complete UE context to SMF 220, including the UE SM context and the UE billing context. Note that UPF 212 can also send the UE billing context to PCF 222. If UPF 212 releases the UE context, then SMF 220 can receive the complete UE context from UPF 212 and can store the complete UE context in local memory. Note that the UPF UE context and the SMF context may have some common fields, such as temporary UE ID, IP address(es), and TFT. To save memory resources, SMF 220 can Petition 870250082301, dated 12 / 09 / 2025, p. 64 / 556 58 / 264 stores only the additional UPF EU context parameters that the SMF EU context does not have. Optionally, SMF 220 can notify AN 204 that all PDU sessions are in the Session-IDLE state by sending an SMF-AN (2050c) notification message of all idle sessions. Also optionally, SMF 220 and UDM 216 can execute an SMF-UDM EU context update procedure (765) as described above. Then, SMF 220 and PCF 222 can execute an SMF-PCF EU context update procedure (1580), which can include the EU CN state and the state of sessions that change their session state. Note that, optionally, the PCF 222 function can also access UDM 216 to obtain the EU context if the policy is to store the EU context in UDM 216.

[00108] Figure 21 illustrates, in a flowchart, an example of a session state transition method (2100), according to the RRC suspension procedure (2000). The method (2100) is executed by SMF 220. SMF 220 can be configured to receive from AMF 218 the AMF-SMF UE CN-Idle state transition request message (2040a), as described above. SMF 220 can then send to AMF 218 the AMF-SMF UE CN-IDLE state transition response message (2040b), as described above. SMF 220 can then send to UPF 212 the request message to disable all SMF-UPF sessions (2050a), as described above. SMF 220 then receives the response message from UPF 212 to disable all SMF-UPF sessions (2050b), as described above. Following this, SMF 220 executes an SMF-PCF UE context update procedure (1580) with PCF 222, as described above.Other steps can be added to method (2100), including SMF optionally sending the notification message of all idle SMF-AN sessions to AN 204, and executing the SMF-UDM UE context update procedure (765), as described. Petition 870250082301, dated 12 / 09 / 2025, p. 65 / 556 59 / 264 above.

[00109] Figure 22 illustrates, in a flowchart, an example of a session state transition method (2200), according to the RRC suspension procedure (2000). The method (2200) is executed by AN 204. AN 204 can be configured to determine the release of a session (2210). The determination (2210) can be based on receiving a UE-AN RRC 202 suspension request message. Alternatively, the determination (2210) can also be based on AN 204 not detecting activities in the UL and DL. Once the determination (2210) is made, AN 204 can send the UE CN-IDLE ANAMF state transition request message (1620a) to AMF 218, as described above. AMF 218 can then send the AN-AMF UE CN-IDLE state transition response message (1620b) to AN 204, as described above. Then, AN 202 can send the UE-AN RRC suspension response message (1630a), as described above.Other steps can be added to method (1800), including AN 204 receiving the notification message of all idle SMF-AN sessions (1650c) from SMF 220, as described above.

[00110] Figure 23 illustrates, in a message flowchart, an example of an RRC resumption procedure (2300), according to an embodiment of the present invention. The procedure (2300) can be triggered when the UE RRC is in an RRCSuspended state and UE 202 has data to send in the UL. The procedure (2300) is triggered when UE 202 sends to AN 204 a UE-AN RRC resumption request message (2310). The message may include at least the RRC resumption ID. Optionally, the RRC resumption request includes the DRB IDs or the session ID to be resumed. If the AN ID denotes the previous (old) AN 204' when the RRC was suspended (note that the previous AN ID is provided in the RRC resumption ID), then the new serving AN 204 and the old AN 204' execute a UE context handover procedure (2320) so that the new serving AN Petition 870250082301, dated 12 / 09 / 2025, p. 66 / 556 60 / 264 204 can obtain the EU context from the old AN 204. After sending the EU context to the new AN serving 204, the old AN 204 can release the EU context.

[00111] Next, AN 204 and AMF 218 execute a CN-CONNECTED state transition procedure from AN-AMF UE (2330). AN 204 can check the UE context to find AMF serving 218. AN 204 can send AMF 218 a CN-CONNECTED state transition request message from AN-AMF UE (2330a). The message can include the temporary UE ID and the new CN-CONNECTED state. Then, AMF 218 can send AN 204 a CN-CONNECTED state transition response message from AN-AMF UE (2330b). If AMF 218 can support UE 202, the CN-CONNECTED state transition response message can include an acknowledgment. Otherwise, the message can include a cause code.

[00112] It should be noted that if the RRC resumption request in step (2310) does not include a DRB ID or Session ID, the following AN-SMF Session-ACTIVE state transition procedure (2400) will not be executed. Additionally, if the CN-CONNECTED state transition response includes a cause code, UE 202 executes a re-attachment procedure and procedure (2400) and step (2380) are not performed. In step (2370), the RRC resumption response may include the cause code generated by AMF 218 in step (2330b). Furthermore, if there are errors in step (2320) or (2330), procedure (2400) and step (2380) are not performed and UE 202 does not resume the suspended RRC connection. In step (2370), AN 204 can send a cause code to UE 202, so that UE can start a new (re)annexation procedure (300).

[00113] AN 204 can send, via AMF 218, to SMF 220 a request message for a Session-ACTIVE state transition from AN-SMF (2340), which may include the session ID, its new Session-ACTIVE state, the SM-NSSAI to be recognized by AMF 218 for Petition 870250082301, dated 12 / 09 / 2025, p. 67 / 556 61 / 264 select the SMF, and the temporary UE ID. The message may include a cause code “RRC Resumed by UE”. If the value of the Activate-Session-when-RRC-Resumed parameter is set to Yes for some PDU sessions, AN 204 may include the session IDs of those PDU sessions in the Session-ACTIVE state transition request. In the case where UE 202 is served by a new AN 204, the AN-SMF SessionACTIVE state transition request may also include an AN path switching request message, which may include the IP address of the new AN serving 204.

[00114] Next, SMF 220 and UPF 212 can execute an SMF-UPF Session-ACTIVE state transition procedure (2350). SMF 220 can send UPF 212 a SMF-UPF Session-ACTIVE state transition request message (2350a). The message can include a temporary UE ID, session IDs, and the new Session-ACTIVE state. If UPF 212 has released the UE context, then SMF 220 can also send UPF 212 the UE context previously stored in the SMF-UPF Session-ACTIVE state transition request message. In the case where UE 202 is served by a new AN 204, the SMF-UPF Session-ACTIVE state transition request may also include the AN path switching request, which may include the IP address of the new AN serving 204. UPF 212 prepares its resources according to the UE context.If UPF 212 resources are ready, UPF 212 can send an SMF-UPF Session-ACTIVE state transition response message (2350b) to SMF 220 with an acknowledgment. If UPF 212 has sufficient resources to support the resumed session(s), then the session state in the context of UPF UE 212 can be changed to Session-ACTIVE. If UPF 212 does not have sufficient resources to support the resumed session(s), the Session-ACTIVE state transition response message may include a cause code. Petition 870250082301, dated 12 / 09 / 2025, p. 68 / 556 62 / 264

[00115] SMF 220 can send AN 204 a Session-ACTIVE state transition response message from AN-SMF (2070), which may include the status of the requested session IDs. In its UE context, AN 204 can change the session state from Session-IDLE to Session-ACTIVE. For sessions that are not activated due to errors in steps (2030) and (2050), the Session-ACTIVE state transition response from AN-SMF may include a cause code. Optionally, SMF 220 and UDM 216 can execute an SMF-UDM UE context update procedure (765), as described above.

[00116] SMF 220 and PCF 222 can execute an SMF-PCF UE context update procedure (1580). Then, AN 204 can send UE 202 a UE-AN RRC resumption response message (2370). The message can include an acknowledgment or cause codes for the RRC resumption request. The cause codes can indicate an error from AN 204 (in step (2320)), AMF (in step (2330)), or RRC resumption errors. If in step (2310) the UE-AN RRC resumption request included DRB IDs (or session IDs), the UE-AN RRC resumption response message can also include an acknowledgment or cause code for each requested DRB ID.

[00117] UE 202 has UL data to send in the DRB that was requested in step (2310). UE can send the UL grant request message (2380) to AN 204. AN 204 provides resources for DRB in the UL. After that, UE can send data through the DRB.

[00118] Figure 24 illustrates, in a flowchart, an example of a session state transition method (2400), according to the RRC resumption procedure (2300). The method (2400) is executed by SMF 220. The method involves SMF 220 being configured to receive from AN 204, via AMF 218, the AN-SMF Session-ACTIVE state transition request message (2340), as described above. Then, SMF 220 can send Petition 870250082301, dated 12 / 09 / 2025, p. 69 / 556 63 / 264 to UPF 212 the SMF-UPF Session-ACTIVE state transition request message (2350a), as described above. SMF 220 then receives from UPF 212 the SMF-UPF Session-ACTIVE state transition response message (2350b), as described above. Next, SMF 220 can send to AN 204, via AMF 218, the AN-SMF Session-ACTIVE state transition response message (2360), as described above. Then, SMF 220 executes an SMF-PCF UE context update procedure (1580) with PCF 222, as described above. Other steps can be added to method (2400), including the SMF optionally executing the SM-UDM UE context recovery procedure, executing the SMF-UE context update procedure (765), and receiving from the UE (via AN 204) the UL grant request message, as described above.

[00119] Figure 25 illustrates, in a flowchart, an example of a session state transition method (2500), according to the RRC resumption procedure (2300). The method (2500) is performed by AN 204. The method comprises AN 204 receiving the UE-AN RRC resumption request (2310) from a UE 202, as described above. Then, if the AN ID denotes a previous AN 204'(2510), then the serving AN 204 and the previous AN 204' execute the UE context transfer procedure (2320), as described above. AN 204 can send to AMF 218 the CN-CONNECTED state transition request message from AN-AMF UE (2330a), as described above. AN 204 can then receive the CNCONNECTED state transition response message from AN-AMF UE (2330b) from AMF 218. Then, AN 204 can send to SMF 220, via AMF 218, the Session-ACTIVE state transition request message from AN-SMF (2340), as described above.AN 204 can then receive from SMF 220, via AMF 218, the Session-ACTIVE state transition response message from AN-SMF (2350), as. Petition 870250082301, dated 12 / 09 / 2025, p. 70 / 556 64 / 264 described above. Then, AN 204 can send the UE-AN RRC resume response message to UE, as described above. Other steps can be added to method (2500), including routing UL PDU transmissions received from UE 202 to UPF 212.

[00120] Figure 26 illustrates, in a message flowchart, an example of an individual PDU (2600) SessionIDLE state transition procedure triggered by UE 202 or AN 204, according to an embodiment of the present invention. UE 202 may have its own logic to determine whether the RRC state can be suspended to save power, but without releasing the current session(s). In this scenario, the current session(s) state can be set to Session-IDLE on AN 204, UPF 212, SMF 220, PCF 222, and optionally UDM 216. UE 202 can have multiple PDU sessions, where each session can be served by a single UPF 212 or multiple UPF 212s. UE 202 can access multiple network slices, where each slice can have a separate SMF 220 to serve UE 202. There is a one-to-one mapping between the PDU session ID and the DRB ID.

[00121] The individual PDU Session-IDLE state transition procedure (2600) can be triggered by UE 202 and AN 204. A first possible trigger for the PDU Session-IDLE state transition procedure (2600) occurs when UE 202 sends a DRB suspend request message (2610a) to AN 204. A second possible trigger for the individual PDU Session-IDLE state transition procedure (2600) occurs when AN 204, which is monitoring PDU session activities of all PDU sessions, does not detect UL and DL packets (2610b) from a session after the Session-Monitor-Timeout timer. Note that each PDU session can have a Session-Monitor-Timeout parameter configured by PCF 222. SMF 220 can obtain the Session-Monitor parameter. Petition 870250082301, dated 12 / 09 / 2025, page 71 / 556 65 / 264 Timeout from PCF 222 and send it to AN 204 during the session establishment procedure (700).

[00122] AN 204 can send to SMF 220 a Session-IDLE state transition request message from AN-SMF (2620), which can request setting a single PDU session or multiple PDU sessions to the Session-IDLE state. The message (2620) can include the temporary UE ID, the SM-NSSAI(s), and the session ID(s). A special value of a session ID (e.g., wildcard) can indicate that PDU sessions being served by the same SM indicated in the SM-NSSAI should be set to the idle state.

[00123] Next, SMF 220 and UPF(s) 212 can execute an SMF-UPF Session-IDLE state transition procedure (2630). SMF 220 can send to the UPF(s) 212 that service the PDU session(s) SMF-UPF Session-IDLE state transition request message(s) (2630a), indicating the Session-IDLE state of the PDU session(s). The message (2630a) can include a temporary UE ID and session ID(s). A special session ID value (e.g., wildcard) can indicate that the status of the PDU sessions being serviced by UPF 212 should be set to Session-IDLE. Next, if there are UL or DL ​​packets in the UPF 212 buffer, UPF 212 can send an SMF-UPF Session-IDLE state transition response message (2630b) to SMF 220, which may include a cause code. The session state remains Session-ACTIVE.If there are no DL packets in the UPF 212 buffer, UPF 212 can set the Session-State field of the UE PDU session context to SessionIDLE. UPF 212 can send an SMF-UPF Session-IDLE state transition response message (2630b) to SMF 220 with an acknowledgment. If there are no more active sessions on the same UPF 212, the UE context can be released, and UPF 212 can send the complete UE context, including the SM context and the PCF context, to SMF 220. Petition 870250082301, dated 12 / 09 / 2025, p. 72 / 556 66 / 264

[00124] Next, SMF 220 can send AN 204 a Session-IDLE state transition response message from ANSMF (2640) (response to step (2620)). Message (2640) can include an acknowledgment or the cause code in step (2630b). If UPF 212 releases the UE context, SMF 220 can receive the complete UE context and billing information from UPF 212. SMF 220 can store the complete UE context in local memory and forward the billing information to PCF 222 as in step (2670) below. Note that the UPF UE context and the SMF context may have some common fields, such as the temporary UE ID, the IP address(es), and the TFT. To conserve memory resources, the SMF 220 can only store the UPF UE context parameters that the SMF UE context does not have.

[00125] Next, AN 204 and UE 202 can optionally perform an AN-UE DRB suspension procedure (2650). UE 202 can perform a UE DRB suspension procedure. After this step (2650), there may be no AS signaling for the suspended DRB, and there may be no NAS signaling for the PDU session associated with the suspended DRB. Also optionally, SMF 220 and UDM 216 can perform an SMF-UDM UE context update procedure (765), as described above. However, this step (765) may be mandatory if SMF 220 releases the UE context. The SMF must then send all the EU UP context and the EU SM context to UDM 216. Then, SMF 220 and PCF 222 can execute an EU SMF-PCF context update procedure (1580), which may include an EU CN state, session state that changes its session state, and billing information.Note that, optionally, the PCF 222 function can also access UDM 216 to obtain the EU context if the policy is to store the EU context in UDM 216. Note also that UPF 212 can send the billing context directly to PCF 222. Petition 870250082301, dated 12 / 09 / 2025, page 73 / 556 67 / 264

[00126] Figure 27 illustrates, in a flowchart, an example of a session state transition method (2700), according to the individual PDU Session-IDLE state transition procedure (2600). The method (2700) is executed by SMF 220. The method comprises SMF 220 configured to receive from AN 204, via AMF 218, the AN-SMF Session-IDLE state transition request message (2620), as described above. Then, SMF 220 can send to UPF 212 the SMF-UPF Session-IDLE state transition request message (2630a), as described above. SMF 220 then receives from UPF 212 the SMF-UPF Session-IDLE state transition response message (2630b), as described above. Next, SMF 220 can send the AN-SMF Session-IDLE state transition response message (2640) to AN 204 via AMF 218, as described above.Next, SMF 220 executes an SMF-PCF UE context update procedure (1580) with PCF 222, as described above. Other steps can be added to the method (2700), including the SMF optionally executing the SMFUDF UE context update procedure (765), as described above.

[00127] Figure 28 illustrates, in a flowchart, an example of a session state transition method (2800), according to the individual PDU Session-IDLE state transition procedure (2600). The method (2800) is performed by AN 204. The method comprises AN 204 determining that a session state transition should be performed (2810). The determination (2810) can be made by AN 204 receiving a UE-AN DRB suspend request (2610a), as described above. The determination (2810) can also be made by AN 204 that is monitoring PDU session activities of all PDU sessions and does not detect any UL and DL packets (2610b) from a session after the Session-Monitor-Timeout timer, as described above. AN 204 can then send the message to SMF 220, via AMF 218. Petition 870250082301, dated 12 / 09 / 2025, page 74 / 556 68 / 264 request for Session-IDLE state transition from AN-SMF (2620), as described above. Then, AN 204 can receive from SMF 220, via AMF 218, the Session-IDLE state transition response message from AN-SMF (2640), as described above. Other steps can be added to the method (2800), including AN performing the AN-UE DRB suspension procedure (2650), as described above.

[00128] Figure 29 illustrates, in a message flowchart, an example of a PDU SessionACTIVE state transition procedure (2900), according to an embodiment of the present invention. The procedure (2900) is triggered by a UE UL grant request when UE 202 is in an RRCCONNECTED state and has UL data to be sent in a suspended DRB. UE 202 can send to AN 204 a UE-AN UL grant request message (2910). The message can include the DRB ID(s). If a DRB is in a suspended state, then the UL grant request may imply a request to resume this DRB. If the sessions with session ID(s) associated with the DRB ID(s) are in a SessionIDLE state, then the procedure (2400) can be followed, as described above.Next, AN 204 can send UE 202 a UE-AN UL (2920) grant reply message, which may include the DRB ID(s) or session ID and an acknowledgment or cause code for each DRB. If a cause code is included for a DRB, UE 202 can request a new session when CN 206 cannot resume the inactive session. Upon receiving an acknowledgment from AN 204 in the UE-AN UL (2920) grant reply message, UE 202 can send the UL packet to AN 204 (2930) for the resumed DRB(s). AN 204 can then forward UL (2930) packets to UPF 212.

[00129] Figure 30 illustrates, in a message flowchart, an example of a Session state transition procedure. Petition 870250082301, dated 12 / 09 / 2025, p. 75 / 556 69 / 264 ACTIVE of PDU (3000), according to an embodiment of the present invention. In this scenario, the current session connection state is in the Session-IDLE state. UPF 212 may not have NG3 tunnel information in the UE context. Procedure (3000) can be triggered by UPF 212 receiving a DL packet from a packet data network (PDN) 208. The packet can be buffered in UPF 212. Then, UPF 212 can send to SMF 220a “Get UE Context Update” to obtain the NG3 tunnel endpoint ID. Then, SMF 220 checks the state of CN 206 in its UE context. If UE 202 is in the CN-CONNECTED state, then steps (3030a), (3030b), (3030c) may not be performed.

[00130] If UE 202 is in the CN-IDLE state, SMF 220 can send a “Update UE CN State” request (3030a) to AMF 218 so that AMF 218 can page the UE paging function. The message (3030a) can include the temporary UE ID. Then, AMF 218 can execute a UE paging procedure (3030b). This may involve a UE context handover procedure if UE 202 is served by a new AN 204. If AMF 218 successfully pages UE 202, then the UE enters a CN-CONNECTED state.

[00131] Next, SMF 220 can update the CNCONNECTED state of UE 202. SMF 220 can send AN 204 a Session-ACTIVE state transition request message (3040). The message can include the temporary UE ID, session ID, UE PDU session context, and QoS profile. Then, AN 204 can establish radio resources (3050) with UE 202 for the PDU session. This step (3050) can include admission control, if necessary. Then, AN 204 can send SMF 220 a SessionACTIVE state transition response message (3060) which can include the SM-NSSAI, the temporary UE ID, Petition 870250082301, dated 12 / 09 / 2025, p. 76 / 556 70 / 264 the session ID and an acknowledgment or cause code for this session ID.

[00132] Next, SMF 220 can send a Get EU Context Update (3070) service response to UPF 212. If SMF 220 received a cause code from AMF 218, then SMF 220 can send a cause code to UPF 212 to release the EU context and discard received packets. SMF 220 can also release the EU context. If SMF 220 receives a cause code from AN 204, then SMF 220 can send a cause code to UPF 212. UPF 212 can then discard received packets. If SMF 220 receives an acknowledgment in steps (3030) and (3060), then SMF 220 can send UPF 212 a Get UE Context response (3070) which may include the UE ID, session ID, and NG3 tunnel endpoint ID. Then, SMF 220 and PCF 222 execute the SMF-PCF UE context update procedure (1580), as described above.SMF 220 can request PCF 222 to perform a UE Context Update service where the new session connection state can be sent to PCF 222. The service request from SMF 220 can include the UE ID, the session ID, and the new session connection state.

[00133] Figure 31 illustrates, in a flowchart, an example of a method for performing a Session-ACTIVE state transition (3100), according to the PDU Session-ACTIVE state transition procedure (3000). The method (3100) can be performed by SMF 220. SMF 220 can be configured to receive a Get UE Context Update service request message (3020) from UPF 212. SMF 220 can send a UE CN State Update service request message (3030a) to AMF 218. Then, SMF 220 can receive a UE CN State Update service response (3030c). Then, SMF 220 can send a transition request message to AN 204 via AMF 218. Petition 870250082301, dated 12 / 09 / 2025, p. 77 / 556 71 / 264 Session-ACTIVE state (3040). Then, SMF 220 can receive from AN 204, via AMF 218, a Session-ACTIVE state transition response message (3060). Then, SMF 220 can send to UPF 212 a Get UE Context Update service response message (3070). Then, SMF 220 can perform the SMF-PCF UE context update procedure (1580), as described above. Other steps can be added to the method (3100).

[00134] Figure 32 illustrates, in a message flowchart, an example of a SessionACTIVE state transition procedure of PDU (3200), according to an embodiment of the present invention. The procedure (3200) is triggered by a request from UPF 212 when the PDU session is in the Session-IDLE state and thus UPF 212 may not have the TFT for the DL packet from inactive sessions. The UE PDU context can be stored in SMF 220 or UPF 212. UPF 212 receives a DL packet from a packet data network (PDN) 208 (3210). The packet can be buffered in UPF 212. UPF 212 can send a UPF-SMF UE context request message (3220) to SMF 220. If UPF 212 does not have the UE context, UPF 212 can identify and send the UPF-SMF UE context request to SMF serving 220, which may include packet header information. Note that some application servers may configure a tunnel with UPF 212.This tunnel may be associated with sessions handled by a specific SMF 220. UPF 212 can rely on the tunnel information to identify the SMF serving 220.

[00135] SMF 220 can check the CN status in the context of UE. If UE 202 is in the CN-IDLE state (i.e., UE 202 is in the RRC-IDLE state or the RRC-Suspended state), then SMF 220 can initiate a UE paging procedure (3230). SMF 220 can send an SMF-AMF UE paging request message (3230a) to AMF 218. The message can include the temporary UE ID. AMF 218 can then execute a procedure Petition 870250082301, dated 12 / 09 / 2025, p. 78 / 556 72 / 264 EU paging (3230b). This step may involve an EU context handover procedure if EU 202 is served by a new AN 204. If AMF 218 successfully pages EU 202, then EU 202 enters the CN-CONNECTED state. AMF 218 may send an SMF-AMF EU paging reply message (3230c) to SMF 220, which may indicate that EU 202 is in the CN-CONNECTED state.

[00136] SMF 220 can update UE 202 to be in the CN-CONNECTED state. SMF 220 can send AN 204 a Session-ACTIVE state transition request message from SMF-AN (3240). The message can include a temporary UE ID, session ID, and the Session-ACTIVE status parameter. Optionally, if the DRB is currently suspended, AN 204 initiates an AN-UE DRB resumption procedure (3224). AN 204 can send UE 202 an AN-UE DRB resumption request message (3224a). The message can include DRB IDs. Then, UE 202 resumes the suspended DRB. UE 202 can send AN 204 an AN-UE DRB resumption response message (3224b), which can include the DRB ID, and an acknowledgment or cause code. Note that in step (3224a), the AN-UE DRB resume request message can be implicitly carried in a DL channel grant message.

[00137] AN 204 can send SMF 220 a Session-ACTIVE state transition response message from SMF-AN (3260), which may include the SM-NSSAI, the temporary UE ID, the session ID, and an acknowledgment or a cause code for this session ID. If SMF 220 receives a cause code from AN 204, SMF 220 can initiate the SM establishment procedure (700) triggered by CN 206. Otherwise (SMF 220 receives an acknowledgment from AN 204), SMF 220 can send UPF 212 a UPF-SMF UE context response message (3270), which may include a SessionACTIVE state acknowledgment. If UPF 212 does not have the UE context, the message Petition 870250082301, dated 12 / 09 / 2025, p. 79 / 556 73 / 264 can also include a complete UE context. UPF 212 can configure UP resources to support PDU sessions. Optionally, SMF 220 and UDM 216 can execute an SMF-UDM UE context update procedure (765), as described above. SMF 220 and PCF 222 can execute an SMF-PCF UE context update procedure (1580). UPF 212 can then send the DL packet to UE 202 (3280).

[00138] Figure 33 illustrates, in a flowchart, an example of a session transition method (3300), according to the PDU Session-ACTIVE state transition procedure (3210). The method comprises SMF 220 configured to receive the UPF-SMF UE context request message (3220), as described above. Then, SMF 220 can send to AN 204, via AMF 218, the SMF-AN Session-ACTIVE state transition request (3240), as described above. Then, SMF 220 can receive from AN 204, via AMF 218, the SMF-AN Session-ACTIVE state transition response message (3260), as described above. Then, SMF 220 can send to UPF 212 the UPF-SMF UE context response message (3270), as described above. Next, SFM 220 can execute an SMF-PCF UE context update procedure (1580), as described above.Other steps can be added to method (3300), including SMF 220 executing the SMF-UDM UE context recovery procedure with UDM 216, SMF 220 initiating the UE paging procedure, and SMF 220 performing the SMF-UDM UE context update procedure with UDM 216, as described above.

[00139] Figure 34 illustrates, in a component diagram, an example of an Update UE CN State (3400) service procedure. AMF 218 can provide a service to page UE 202 when UE 202 is in the CN-IDLE state. AMF 218 can maintain the UE context. A requester 3405 can send an Update UE CN State (3410) request message. Petition 870250082301, dated 12 / 09 / 2025, page 80 / 556 74 / 264 to AMF 218. The message may include the UE ID. Requester 3405 may be SMF 220 as in step (3030a) above. Requester 3405 may also be any network function that can communicate with AMF 218. AMF 218 may then send requester 3405 a reply message of Update UE CN status (3420), which may include an acknowledgment of the UE's CN-CONNECTED status and the IP address of AN 204. If a paging failure occurs, the reply may include a cause code.

[00140] Figure 35 illustrates, in a component diagram, an example of a PDU Session Modification service procedure (3500). This service (3500) provides the PDU session modification service, such as QoS parameters and billing parameters. SMF 220 can maintain the UE context. A requester 3505 can send a session modification request message (3510) to SMF 220. The message can include the UE ID, the PDU session ID, and the new session parameters. The requester 3505 can be any network function that can communicate with SMF 220. Then, SMF 220 can send the requester 3505 a Session Modification message (3520) to confirm the completion of the service. The message (3520) can include an acknowledgment or a cause code.

[00141] Figure 36 illustrates, in a component diagram, an example of a Get EU Policy (3600) service procedure. PCF 222 can provide EU policies to a requester 3605. PCF 222 can have policies for services, DN 208, time zone, and EU 202. A requester 3605 can send a Get EU Policies (3610) request message to PCF 222. The message can include the PDU session type, DN name, EU 202 time zone, and the requested policy, such as the SM policy, access and mobility (AM) policy, QoS policy, and billing policy. The requester 3605 can be any network function that can communicate with the Petition 870250082301, dated 12 / 09 / 2025, page 81 / 556 75 / 264 PCF 222. Next, PCF 222 can send requester 3605 a Get UP Policy (3620) reply message, which may include the requested policy.

[00142] Figure 37 illustrates, in a component diagram, an example of a UE Context Update service procedure (3700). PCF 222 can provide a UE context update service to requester 3605 for some scenarios, including dynamic policy. PCF 222 can have policies for services, DN 208, time zone, and UE 202. A requester 3605 can send a UE Context Update request message (3710) to PCF 222. The message can include the UE ID, the session ID(s), and a list of parameters and their corresponding new values. Requester 3605 can be SMF 220 as in step (1580) above. The requester can also be any network function that can communicate with PCF 222. PCF 222 can then store new parameter values ​​for the EU context.PCF 222 can send requester 3605 an EU Context Update reply message (3720) to confirm that the service has been performed or to report an error (via a cause code).

[00143] Figure 38 illustrates, in a component diagram, an example of a UE Context Update service procedure (3800). When a PDU session has been established, UPF 212 may have the UE context. A requester 3805 may send to UPF(s) 212 serving the PDU session a UE Context Update request message (3810). The message may include the UE ID, the session ID(s), and a list of parameters and their corresponding new values. The new value may be NULL. If a new tunnel endpoint ID is NULL, UPF 212 may contact SMF 220 if UPF 212 does not know how to forward the packet. Requester 3805 may be SMF 220 as in step (3070) above. Requestor 3805 can also be any network function that Petition 870250082301, dated 12 / 09 / 2025, p. 82 / 556 76 / 264 can communicate with UPF 212. UPF 212 can receive new session parameters and check if the new parameters can be supported. If the new parameters can be supported, UPF 212 can reconfigure or release its resources that serve the PDU session. UPF 212 can send to SMF 220 the SMF-UPF session modification response message (3820) which may include an acknowledgment to confirm that the service was performed or to report an error (through a cause code).

[00144] Figure 39 is a 3900 call flowchart illustrating methods that can be performed on a number of different nodes and functions for a SessionIDLE state transition of a UE under a CM_Connected mode. As shown in Figure 39, there can be several different triggers for initiating the session connection state transition procedure. As illustrated in Figure 39, a UE 202 or an AN 204 can request the session IDLE transition. Experts in the art will appreciate that other triggers may also be applicable. Either the UE 202 or the AN 204 can issue a session IDLE transition request (in 3902a and 3902b) towards SMF 220. In some instances, the request message may include the temporary UE ID, the Session ID(s), a Session-IDLE state, or an AD ID, as appropriate. The information included in the message may differ depending on the node or function that initiates the message.A special session ID value (e.g., wildcard) can be used to denote all PDU sessions that meet the identification requirements included in the request. It should also be understood that SMF 220 can initiate the session_idle state transition in response to another external trigger or in response to an internal condition being met. SMF 220 and UPF 212 communicate with each other to perform a session update. SMF 220 can transmit a session update request (e.g., a session update request). Petition 870250082301, dated 12 / 09 / 2025, page 83 / 556 77 / 264 of N4) 3904a to UPF 212. This request may serve as a request to UPF 212 to release NG3 information associated with an AN from the UE PDU session context (as identified by UPF). This session information may include the AN 204 tunnel endpoint ID and the AN IP address. In response to this request, UPF 212 may release the session and transmit a 3904b response to SMF 220 to confirm completion of the UE context update request. SMF 220 can then send a session update request 3906 to AN 204, which can optionally be routed through AMF 218. In some embodiments, this may take the form of an N2 session update request sent to AN 204 via AMF 208. The session update request may include information such as temporary UE ID, Session ID(s), and Session-IDLE status.In response to receiving the session update request, AN 204 and UE 202 can execute a connection reconfiguration procedure RRC 3908 to release resources allocated to the session(s). AN 204 can inform UE 202 of the session state transition through the procedure. Experts in the art will appreciate that there may be more detail regarding the interaction between UE 202 and AN 204, but these implementation details may vary from solution to solution. After releasing the PDU (or sessions) session context, AN 204 can send a 3910 response to the Session Update Request (a Session Update Response, like an N2 Session Update Response). This response can be sent to SMF 220, and optionally via AMF 208. The response can serve to confirm the completion of the Session-IDLE state transition in UE 202, and may include the temporary UE ID and Session ID.At this point, SMF 220 can set the session connection state (in 3912) from the EU context to Session-IDLE. Experts in the field will appreciate what other services can be called upon. Petition 870250082301, dated 12 / 09 / 2025, page 84 / 556 78 / 264 transfer the session update request and response without deviating from the intended method. It should also be understood that a Policy Control Function may also be involved.

[00145] Figure 40 is a call flowchart illustrating methods that can be performed on a number of different nodes and functions for a UE-triggered Session-ACTIVE State Transition under CM_Connected mode. As shown in Figure 40, the method can be initiated by a UE 202 transmitting a request to SMF 220 for a transition to an active session. As shown in Figure 40, step 4002, UE 202 sends a Session-ACTIVE request to SMF 220 (optionally via AMF 218). The message can include the temporary UE ID, Session ID(s), and Session-ACTIVE status. It should be understood that a special Session ID value (e.g., wildcard) can be used to denote all PDU sessions that satisfy other conditions specified in the request.In response, SMF 220 can send (on 4004) a session update request, such as an N2 Session Update Request, to AN 204, for example, via AMF. 218 The session update request message can include a temporary UE ID, a Session ID, a Session-ACTIVE state, and NG3 connection information. AN 204 and UE 202 can execute an RRC connection reconfiguration procedure (on 4006). In one embodiment, the RRC connection reconfiguration procedure can involve AN 204 assigning radio resources to serve the PDU session according to a QoS profile. If the QoS profile requires admission control, AN 204 can perform admission control (or can invoke an admission control procedure). If there are insufficient radio resources to meet the needs of the PDU session, or if AN 204 cannot support the session, AN 204 may instruct or inform UE 202 to release the PDU session. Petition 870250082301, dated 12 / 09 / 2025, p. 85 / 556 If there are sufficient radio resources and AN 204 can support the session, AN 204 can send an RRC Connection Reconfiguration message to UE 202 indicating the allocation of radio resources. According to the RRC connection configuration, UE 202 can set the session connection state to Session-ACTIVE. It will be understood by those skilled in the art that other steps can be taken as substitutes for RRC connection reconfiguration. The addition of these steps may vary from implementation to implementation and is therefore not discussed here. When configuring (or reconfiguring, as the case may be) the RRC connection, AN 204 can send a session update reply message (on 4008) towards SMF 220. Optionally, this message can be sent to AMF 218 for delivery to SMF 220. In some embodiments, the message may be an N2 Session Update Reply. The message may include the temporary EU ID and the Session ID.AN 204 can use this 4008 response message to notify SMF 220 of successful completion of the Session-ACTIVE state transition or a cause code associated with a failure to successfully complete the transition, for example, lack of radio resources to support the PDU session. If SMF 220 is notified of a successful transition completion, it can transmit a request to UPF 212 to update the UE session context. This can take the form of 4010a and 4010b messages in response. If SMF 220 is not notified of a success (including the scenario where you are notified of a failure), steps 4010a and 4010b can be omitted. As shown in 4010a, SM 220 can transmit a request to UPF 212 to update the session information.This can take the form of an N4 Session Update Request sent to UPF 212 requesting an update of the NG3 information associated with AN 204 that is associated with the UE PDU session context in UPF 212. The request message can include a temporary UE ID, Session ID, and NG3 information, including the endpoint ID. Petition 870250082301, dated 12 / 09 / 2025, p. 86 / 556 The 80 / 264 tunnel of AN and the AN's IP address. In response, UPF 212 can transmit an acknowledgment as shown in 4010b. This acknowledgment can take the form of an N4 Session Update response. If SMF 220 receives an indication from AN 204 that the RRC connection reconfiguration was successful, SMF 220 can set the session connection state (in 4012) in the UE context accordingly. If the session connection state transition is successful, SMF 220 can set the session connection state to Session-ACTIVE. If the session connection state transition is unsuccessful (e.g., the AN cannot support the PDU session), SMF 220 can initiate a Session Release procedure. As mentioned above, in relation to Figure 39, PCF may be involved during session connection state transition procedures. It should also be understood that different services may be involved in the transfer of N2 messages.

[00146] The procedure to release a NAS signaling connection can be initiated by a 5G (R)AN 204 node or AMF 218. AMF 218 can inform SMF 220 that UE 202 enters the CM-IDLE state so that SMF 220 can inform UPF(s) 212 to disable existing PDU sessions by releasing the N3 tunnel information (including (R)AN IP address and Tunnel Endpoint Identifier) ​​from the UE context on UPF 212. UE 202 can consider the NAS signaling connection released if UE detects that the RRC connection is released. After the NAS signaling connection is released, UE 202 and AMF 218 can enter the CM-IDLE state.

[00147] When a UE 202 has multiple established PDU sessions, activating UP connections from existing PDU sessions may cause a UE-CN user plane connection (i.e., data radio carrier and N3 tunnel) to a PDU session to be activated. For the UE 202 in the CM-IDLE state, the service request procedure is triggered by the network or by Petition 870250082301, dated 12 / 09 / 2025, page 87 / 556 81 / 264 UE 202 can support independent activation of the UP connection of an existing PDU session. For UE 202 in the CM-CONNECTED state, independent activation and deactivation of UP connections of existing PDU sessions can be supported.

[00148] There may be different types of PDU session establishment procedures. One type of session establishment procedure may be a UE 202 initiated PDU session establishment procedure. Another type of session establishment procedure may be a network initiated PDU session establishment procedure. In the case of a network initiated procedure, the network may send the device trigger message to the application(s) on the UE side. The trigger payload included in a device trigger request message may include information about which application on the UE side should trigger the PDU session establishment request. Based on this information, the application(s) on the UE side trigger the PDU session establishment procedure.

[00149] There may be different modes of PDU session deactivation. One type of session deactivation procedure may be that all UE 202 PDU sessions may be deactivated when the UE CM state transitions from the CMCONNECTED state to the CM-IDLE state. Another type of session deactivation procedure may be (R)AN 204 initiating all PDU session deactivation. (R)AN 204 may inform AMF 218 of the cause of the RRC release, such as O&M intervention, unspecified failure, user inactivity, repeated RRC signaling integrity check failure, release due to signaling connection release generated by UE 202, etc. Another type of session deactivation procedure may be AMF 218 initiating all PDU session deactivation due to authentication failure. Another type of session deactivation procedure may include (R)AN 204 initiating a deactivation of Petition 870250082301, dated 12 / 09 / 2025, page 88 / 556 82 / 264 Selective PDU session. (R)AN 204 can inform SMF 220, via AMF 218, of the cause of the selective PDU session, such as O&M intervention and user inactivity.

[00150] A procedure can be used to release an N2 connection and simultaneously disable PDU sessions when UE 202 enters the CM-IDLE state. Figure 41 illustrates, in a message flowchart, an example of a PDU session disabling procedure (4100), according to an embodiment of the present invention. UE 202 and (R)AN 204 can perform an RRC Release (600A). If the RRC connection is released, (R)AN 204 can interact with UE 202 to release the RRC signaling connection. UE 202 enters the CM-IDLE state and all PDU sessions can be disabled. Thus, UE 202 knows that the RRC release involves disabling PDU sessions. Next, (R)AN 204 can send (N2 message) an RRC Release Notification (4102) to AMF 218. The message (4102) can include a cause code, such as O&M intervention, UE downtime, etc. In certain scenarios, step (600A) can be initiated before or in parallel with step (4102).

[00151] Next, (R)AN 204 can create (N11 message) one or more N2 Release Notification messages and send them (4104) via AMF 218 to the SMF(s) 220 that handle the PDU sessions to be disabled. The message (4104) can include a UE ID to identify the UE (such as temporary UE ID or SUPI), a list of PDU session ID(s) to be disabled, and a cause code. Alternatively, the message (4104) includes a UE ID to identify the UE (such as temporary UE ID or SUPI), (R)AN information, a list of PDU session ID(s) to be disabled, PDU session ID, and cause code. The (R)AN information indicates the IP address of the (R)AN that releases the RRC connection. Next, SMF 220 can send (N4 message) an N3 Release Request (4106) to UPF(s) 212. The message (4106) can include a UE ID (such as ID Petition 870250082301, dated 12 / 09 / 2025, p. 89 / 556 83 / 264 temporary UE or SUPI) to identify the UE, and PDU session ID(s) to be disabled. Then, UPF 212 can discard any remaining packets from disabled PDU sessions, if any. UPF 212 can release N3 tunnel information (such as the (R)AN IP address and Tunnel Endpoint Identifier) ​​in the context of the UE PDU session from PDU sessions to be disabled. UPF 212 can send (N4 message) an N3 release response (4108) to SMF 220 confirming the release of N3 tunnel information.

[00152] SMF 220 can send (N11 message) an N2 Release Notification Acknowledgment (4110) to AMF 218 to confirm receipt of the AMF 218 notification (4104). Message (4110) can be sent before, after, or in parallel with message (4106). AMF 218 can then collect all responses from SMF 220 that were reported (in step (4104)). Once all acknowledgments from SMF 220 are collected, AMF 218 can send (N2 message) an N2 Release Request (4112) to (R)AN 204 with a cause code. If step (600A) was not performed previously in the first step of procedure (4210), (R)AN 204 and UE 202 can execute the RRC Release procedure (600A). (R)AN 204 can request that UE 202 release the RRC connection. UE 202 enters the CM-IDLE state and all PDU sessions on UE 202 can be disabled.After receiving confirmation of RRC connection release from UE 202, (R)AN 204 removes the UE context.

[00153] Next, the (R)AN can send (N2 message) an N2 Release Response (4114) to AMF 218. This message (4114) is to provide confirmation for step (4112). Upon receiving the N2 Release Response message (4114), AMF 218 can set the CM-IDLE state in the UE context and release the UE N2 connection. Then, AMF 218 can send (N11 message) an N2 Release Confirmation (4116) to the(s) Petition 870250082301, dated 12 / 09 / 2025, page 90 / 556 84 / 264 SMF(s) 220 to confirm the release of the N2 connection. Alternatively, message (4116) can be omitted.

[00154] In another embodiment, if the RRC Release procedure (600A) has been performed in the first step of the procedure (44100), messages 4112, 4114 and the RRC Release Procedure (600A) between steps that messages 4112 and 4114 may be omitted.

[00155] Figure 42 illustrates, in a flowchart, an example of a method for releasing an N2 connection and disabling a PDU session (4200), according to the N2 Release and PDU Session Disabling procedure (4100). The method (4200) can be performed by AMF 218. The method (4200) involves AMF 218 configured to receive an RRC Release Notification message (4102). Next, AMF 218 sends an N2 Release Notification message (4104) to SMF 220. Then, AMF 218 receives an N2 Release Notification Acknowledgment message (4110) from SMF 220. Next, AMF sends an N2 Release Request message (4112) to (R)AN 204. Then, AMF 218 receives an N2 Release Confirmation message (4114) from (R)AN 204. Other steps can be added to the method (4200).

[00156] Figure 43 illustrates, in a flowchart, another example of a method for releasing an N2 connection and disabling a PDU session (4300), according to the N2 Release and PDU Session Disabling procedure (4100). The method (4300) can be executed by SMF 220. The method (4300) comprises SMF 220 configured to receive an N2 Release Notification message (4104) from AMF 218. Then, SMF 220 sends an N3 Release Request message (4106) to UPF 212. Next, SMF 220 receives an N3 Release Response message (4108) from UPF 212. Then, SMF 220 sends an Acknowledgment message. Petition 870250082301, dated 12 / 09 / 2025, page 91 / 556 85 / 264 of N2 Release Notification (4110) for AMF 218.

[00157] A procedure can be used to release an N2 connection when UE 202 enters the CM-IDLE state or to disable PDU sessions when (R)AN 204 triggers selective PDU session disabling. Figure 44 illustrates, in a message flowchart, an example of a PDU session disabling procedure (4400), according to an embodiment of the present invention. UE 202 and (R)AN 204 can execute an RRC Release procedure (600A) or an RRC Reconfiguration procedure (600B). If the RRC connection is released, (R)AN 204 can interact with UE to release the RRC signaling connection (procedure 600A). UE enters the CM-IDLE state and all PDU sessions are disabled. If some PDU sessions are deactivated, then (R)AN 204 can interact with UE 202 to release DRB(s) belonging to the deactivated PDU sessions (procedure 600B).UE 202 can know that releasing all DRBs belonging to a PDU session implies the deactivation of corresponding PDU sessions. The (R)AN can send (N2 message) a PDU Session Deactivation Request (4402) to AMF 218. The message (4402) can include a PDU session ID(s), and a cause code. The cause code can be RRC release with a reason, such as O and M intervention, UE inactivity, etc. The cause code can also be PDU session inactivity. In the case of an RRC release, the PDU session deactivation request does not include a PDU session ID. In the case of PDU session inactivity, the PDU session deactivation request (4402) can include a list of PDU session ID(s). Note that, in certain scenarios, step (600A or 600B) may be initiated before or in parallel with step (4402).

[00158] Next, AMF 218 can create (N11 message) one or more PDU Session Disable Requests and send them to the SMF(s) 220 that handle the PDU sessions to be Petition 870250082301, dated 12 / 09 / 2025, p. 92 / 556 86 / 264 disabled (4404). The message (4104) may include a UE ID to identify the UE (such as temporary UE ID or SUPI), a list of PDU session ID(s) to be disabled, and a cause code. Then, SMF 220 may send (N4 message) an N3 Release Request (4106) to UPF(s) 212. The message (4106) may include a UE ID (such as temporary UE ID or SUPI) to identify UE 204 and PDU session ID(s). UPF 212 may release the N3 AN tunnel information (i.e., (R)AN IP address and tunnel ID) in the context of the UE PDU session of PDU sessions to be disabled. UPF 212 can send (N4 message) an N3 release response (4108) to SMF 220 confirming the release of tunnel information from N3.

[00159] Next, SMF 220 can send (N11 message) a PDU session disable response (4406) to AMF 218 to confirm the release of N3 tunnel information on UPF(s) 212. Then, AMF 218 can collect all responses from SMF(s) 220 that requested to disable PDU sessions (in step (4404)). Once all responses from SMF 220 are collected, AMF 218 can send (N2 message) a PDU Session Connection Release request (4408) to (R)AN 204. If (R)AN 204 or AMF 218 has initiated the deactivation of all PDU sessions, the (4408) message may include an indication to release the UE context (i.e., all information related to UE 204, including N3 tunnel information and N2 connection). If selective PDU session deactivation is the case, the (4408) message may include a list of PDU session IDs.

[00160] If step (600A or 600B) was not performed previously in the first step of the procedure (4400), (R)AN 204 and UE 202 can execute the RRC Release procedure (600A) or RRC reconfiguration (600B). If the message in step (4408) includes an indication to release the UE context, the Petition 870250082301, dated 12 / 09 / 2025, p. 93 / 556 87 / 264 (R)AN 204 can request UE 202 to release the RRC connection (600A). UE 202 enters the CM-IDLE state and all PDU sessions on UE 202 can be disabled. After receiving confirmation of the RRC connection release from UE 202, (R)AN 204 removes the UE context. If the message in step (4408) included an indication to disable a list of PDU sessions, (R)AN 204 and UE execute a DRB release procedure (600B). UE knows that releasing all DRBs belonging to a PDU session implies disabling a corresponding PDU session. Upon receiving confirmation of the DRB release from UE 202, (R)AN 204 removes the UE's PDU session context from disabled PDU sessions.

[00161] Next, (R)AN 204 can send (N2 message) a PDU Session Connection Release response (4410) to AMF 218. Message (4410) provides confirmation for step (4408). If the message in step (4408) indicates UE context release, AMF 218 can set the CM-IDLE state in the UE context and release the UE N2 connection. Then, AMF 218 can create (N11 message) a PDU Session Disable Confirmation and send it (4412) to SMF(s) 220 to confirm the PDU session(s) disable on (R)AN 204.

[00162] Figure 45 illustrates, in a flowchart, an example of a method for disabling a PDU session (4500), according to the PDU session disabling procedure (4400). The method (4500) can be executed by AMF 218. The method (4500) comprises AMF 218 configured to receive a PDU Session Disabling Request message (4402) from (R)AN 204. Then, AMF 218 can send a PDU Session Disabling Request Message (4404) to SMF 220. Then, AMF 218 can receive a PDU Session Disabling Response message (4406) from SMF 220. Then, AMF 218 can send a Release message. Petition 870250082301, dated 12 / 09 / 2025, page 94 / 556 88 / 264 PDU Session Connection (4408) to (R)AN 204. Then, AMF 218 can receive a PDU Session Connection Release response message (e) from (R)AN 204. Then, AMF 218 can send a PDU Session Disable Confirmation message (4412) to SMF 220. Other steps can be added to method (4500).

[00163] Figure 46 illustrates, in a flowchart, another example of a method for disabling a PDU session (4600), in accordance with the PDU session disabling procedure (4400). The method (4600) can be executed by SMF 220. The method (4600) comprises SMF 220 configured to receive a PDU Session Disable Request message (4404) from AMF 218. Then, SMF 220 sends an N3 release request message (4106) to UPF 212. Next, SMF 220 receives an N3 release reply message (4108) from UPF 212. Next, SMF 220 sends a PDU Session Disable reply message (4406) to AMF 218. SMF 220 receives a PDU Session Disable Acknowledgement message (4412) from AMF 218. Other steps can be added to the method (4600).

[00164] A service request procedure can be used by a UE 5G 204 in CM-IDLE state to request the establishment of a secure connection with an AMF 218. The UE 202 in CM-IDLE state can initiate the service request procedure to send uplink signaling messages, user data, or a response to a network paging request. After receiving the service request message, the AMF 218 can perform authentication, and the AMF 218 can execute the security procedure. After establishing a secure signaling connection to an AMF 218, the UE 202 or network can send signaling messages, for example, establishing a PDU session from the UE 202 to the network, or the SMF 220, through the AMF 218, can initiate the Petition 870250082301, dated 12 / 09 / 2025, page 95 / 556 89 / 264 User plan resource establishment for PDU sessions requested by the network and / or indicated in the service request message. When UE 202 is in the CMCONNECTED state, UE 202 can use another SM procedure to request user plan resource establishment for inactive PDU sessions.

[00165] Figure 47 illustrates, in a message flowchart, another example of a sessionACTIVE (4700) state transition procedure, according to an embodiment of the present invention. UE 202 can send, in a message from N1, a Session Activation Request (4702) to SMF 220. The message (4702) can include the session ID(s) of the PDU to be activated. The message (4702) may not need to include the list of PDU sessions available in UE 202. The list of PDU sessions available in UE 202 can be included if UE 202 has released some PDU sessions but has not informed SMF 220. (R)AN 204 can forward the Session Activation Request from N1 message to AMF 218 via the N2 interface. (R)AN 204 does not need to include the location of UE 202, RAT type, and temporary UE 5G ID in AMF 218.AMF 218 can select SMF 220 based on the PDU session ID and forward the SM Session Activation Request (4704) to the SMF serving 220 over the N11 interface. The forwarded message (4704) can include a UE ID to identify the UE, such as temporary 5G UE ID or SUPI, and PDU session ID(s).

[00166] SMF 220 can use a Message Transfer service provided by AMF 218 to send an N11 message (4706), which contains N2 SM information to be sent to (R)AN 204 and an N1 SM Session Activation Acceptance NAS message to be sent to the UE via the N11 interface. The N11 message may include a UE ID to identify the UE (such as temporary 5G UE ID or SUPI) and PDU Session ID(s). The N2 SM information message may include ID(s) of Petition 870250082301, dated 12 / 09 / 2025, p. 96 / 556 90 / 264 PDU session, and the UE PDU session context (QoS profile and UPF 212 N3 tunnel termination information (UPF IP address and Tunnel Endpoint Identifier)). Then, AMF 218 can read the UE ID (such as temporary 5G ID or SUPI) and PDU session ID to find (R)AN 204. AMF 218 transfers the content of the N11 message (4706), which contains N2 SM information and the N1 SM Session Activation Acceptance NAS message received from the SMF in the N2 message 4708 to the (R)AN on the N2 interface. Next, (R)AN 204 and UE 202 can execute an RRC Connection Reconfiguration (600B) procedure according to the QoS profile for all QoS flows of the enabled PDU session provided in the N2 SM Information.If (R)AN 204 can support the PDU session, the RRC connection reconfiguration message sent from AN 204 to UE 202 can indicate the allocation of radio resources for the PDU session(s); and (R)AN 204 forwards the N1 SM Session Activation Acceptance NAS message provided in message (4708) to UE. After the user plane radio resources are configured, the uplink data from UE 202 can now be forwarded (4710) to RAN 204. RAN 5G 204 can send the uplink data (4710) to the UPF address 212 and tunnel ID provided in step (4706).

[00167] Next, (R)AN 204 can send (N2 message) an (R)AN N3 Information (4712) to SMF 220 via AMF 218. The message (4712) can include the PDU session ID(s), a RAT type, a list of accepted QoS flows and a list of rejected QoS flows for the corresponding activated PDU session, and (R)AN N3 tunnel information ((R)AN IP address and tunnel ID). Then, AMF 218 transfers (N11 message) the (R)AN N3 Information (4714) to SMF 220 by reading the PDU session ID(s) through the N11 interface. The message (4714) can include the UE ID to identify the UE (as a temporary ID). Petition 870250082301, dated 12 / 09 / 2025, p. 97 / 556 91 / 264 5G or SUPI), PDU session ID(s), RAT type, a list of accepted QoS flows and a list of rejected QoS flows for the corresponding enabled PDU session, and N3 (R)AN tunnel information ((R)AN IP address and tunnel ID). Optionally, if dynamic PCC is deployed, SMF 22 0 can initiate IP-CAN session modification (4716) and provide new UE 202 location information to PCF 222.

[00168] In another embodiment, (R)AN 204 may include the SMF Identifier in the message (4712). AMF 218 may read the SMF ID, not the PDU session ID(s), to forward the (N2 message) (R)AN N3 Information (4714) to SMF 220.

[00169] If in step (4712), AN 204 successfully notifies the completion of a session activation, then SMF 220 requests UPF 212 to update the UE PDU session context. In this case, SMF 220 may send an N4 message session update request (4718) to UPF 212 to update the N3 tunnel information from (R)AN 204. The message (4718) may include an ID to identify the UE (such as temporary 5G ID or SUPI), PDU session ID(s), and (R)AN tunnel information (N3 tunnel endpoint ID IP address and (R)AN 204). Then, UPF 212 may send an N4 message session update reply (4720) to SMF 220 to confirm the completion of the session update request.

[00170] Figure 48 illustrates, in a flowchart, an example of a session transition method (4800), according to the session-ACTIVE state transition procedure (4700) of Figure 47. The method (4800) can be executed by AMF 218. The method (4800) comprises AMF 218 configured to receive a Session Activation Request message from SM (4702) from UE 202, through AN 204. Then, AMF 218 sends a Session Activation Request message from SM (4704) to SMF 220. Then, AMF 218 receives a message from N11 containing N2 SM information and Session Activation Acceptance. Petition 870250082301, dated 12 / 09 / 2025, page 98 / 556 92 / 264 of N1 SM (4706) from SMF 220. Then, AMF 218 sends an N2 Message containing N2 SM information and N1 SM Session Activation Acceptance (4708) to AN 204. Then, AMF 218 receives an (R)AN N3 Information message (4712) from AN 204. Then, AMF 218 sends an (R)AN N3 Information message (4714) to SMF 220. Other steps can be added to method (4800).

[00171] Figure 49 illustrates, in a flowchart, an example of a session transition method (4900), according to the Session-ACTIVE state transition procedure (4700) of Figure 47. The method (4900) can be executed by SMF 220. The method (4900) comprises SMF 220 configured to receive a Session Activation Request message (4704) from AMF 218. Then, SMF 220 sends an N11 message containing N2 SM information and N1 SM Session Activation Acceptance (4706) to AMF 218. Then, SMF 220 receives an N3 (R)AN Information message (4714) from AMF 218. Then, SMF 220 can optionally execute an IP-CAN Session Modification. (4716) with PCF 222. Then, SMF 220 sends a Session Update Request message (4718) to UPF 212. Then, SMF 220 receives a Session Update Response message (4720) from UPF 212. Other steps can be added to method (4900).

[00172] Figure 50 illustrates, in a message flowchart, an example of a service request procedure (5000), according to an embodiment of the present invention. UE 202 can send to (R)AN 204 a NAS MM service request (5002). The message (5002) can include PDU session ID(s), security parameters, and PDU session status. UE 202 can send a NAS message service request to AMF 218 encapsulated in an RRC message to RAN 204.

[00173] If UE 202 is in CM-IDLE state, then UE 202 can send the MM NAS service request message. Petition 870250082301, dated 12 / 09 / 2025, p. 99 / 556 93 / 264 (5002). UE 202 can include the temporary 5G ID in the RRC message (5002) between UE 202 and (R)AN 204. (R)AN 204 can route the MM NAS service request message to the correct AMF 218 according to the temporary 5G ID. If UE 204 is in the CM-IDLE state, then UE 202 can send the MM NAS service request message (5002). UE 202 can include security parameters in the NAS message (5002). The PDU session status can be included. Alternatively, the PDU session status can only be included if UE 202 releases some PDU sessions but has not informed SMF 220.

[00174] If UE 202 is in the CM-CONNECTED state, UE 202 can send the MM NAS service request message (5002). The MM NAS service request message (5002) can be encrypted and have its integrity protected. The message (5002) can include PDU session IDs to be activated. The PDU session status can be included. Alternatively, the PDU session status can be included if UE 202 has released some PDU sessions but has not reported SMF 220.

[00175] If UE 202 is triggered for user data, UE 202 may include the PDU session ID(s) in the NAS service request message (5002) to indicate the PDU session that UE 202 selects to activate. If UE 202 is triggered only for signaling, UE 202 may not send any PDU session ID. When this procedure (5000) is triggered for paging response, if UE 202 needs to activate the PDU session(s), it will include the PDU session ID(s) in the NAS MM service request message (5002) to indicate the PDU session that UE 202 needs to activate. Otherwise, UE 202 does not need to include any PDU session ID. The PDU session status may indicate the PDU sessions available on UE 202.

[00176] Next, (R)AN 204 can send an N2 message (MM NAS service request (5004)) to AMF 218. A Petition 870250082301, dated 12 / 09 / 2025, page 100 / 556 Message 94 / 264 (5004) may include a temporary 5G ID, location information, a RAT type, and an RRC establishment reason. If AMF 218 cannot handle service request (5004), it will be rejected.

[00177] If UE 202 is in CM-IDLE state, then the temporary 5G ID can be obtained in an RRC procedure. RAN 204 can select AMF 218 according to the temporary ID. Location information and RAT type refer to the cell in which UE 202 is camped.

[00178] If the UE is in the CM-CONNECTED state, (R)AN 204 forwards the MM NAS Service Request message to AMF 218 without adding temporary 5G ID, location information, RAT type, or RRC establishment cause.

[00179] Based on the PDU session status, AMF 218 can initiate a PDU session release procedure if the PDU session is not available in UE 202.

[00180] Next, if the service request (5004) was not sent with integrity protected, or integrity protection is indicated as failed, AMF 218 can initiate the NAS security / authentication procedure (5006) with UE 202 and AUSF 214. If UE 202 is triggered to establish signaling connection, after the security exchange, UE 202 can send uplink signaling and the rest of this procedure is skipped. If UE is in the CM-CONNECTED state, step (5006) is skipped.

[00181] Next, AMF 218 can conditionally send an N11 (5008) message to SMF 220 that includes a UE identifier (SUPI) and PDU session ID(s). If the MM NAS service request message (5004) includes PDU session ID(s), or this procedure is triggered by SMF 220, AMF 218 can send an N11 (5008) message to SMF(s) 220 associated with the PDU session ID(s). Then, SMF 220 can conditionally send an N11 message to AMF 218. Petition 870250082301, dated 12 / 09 / 2025, p. 101 / 556 95 / 264 (5010) which includes N2 SM information (QoS profile, N3 CN tunnel information) and NAS SM Session Activation Acceptance (with PDU session IDs) to AMF 218. After receiving the N11 (5008) message, each SMF 220 can send an N11 (5010) message to AMF 218 to establish the user plan(s) for the PDU sessions. N2 SM Information may include information that AMF 218 can provide to RAN 204. The SM NAS Session Activation Acceptance message may include information that AMF 218 can provide to UE 202. SMF 220 may use a "Message Transfer" service provided by AMF 218 to send N2 SM Information and SM NAS Session Activation Acceptance.

[00182] Next, AMF 218 can conditionally send to (R)AN 204 an N2 request (5012) that includes N2 SM information and SM NAS session activation acceptance received from SMF 220, a security context, an AMF 218 signaling connection ID, a handover restriction list, and an MM NAS service acceptance. If the service request (5000) was triggered by a UE 202 in the CM-IDLE state, AMF 218 can include the security context, an AMF signaling connection ID, and a handover restriction list in the N2 request (5012). RAN 204 can store the security context, AMF signaling connection ID, QoS information for the QoS flows of the PDU sessions that are activated, and N3 tunnel IDs in the UE RAN context.If the service request (5000) was triggered when UE 202 is in the CMCONNECTED state, AMF 218 can transfer the N2 SM Information (QoS profile, CN N3 tunnel information) and the SM NAS Session Activation Acceptance to (R)AN 204, without adding the security context, the AMF signaling connection ID, the handover restriction list, or the MM NAS service acceptance. If there are multiple PDU sessions involving multiple SMFs 220, AMF 218 can wait for responses from all SMFs 220. Petition 870250082301, dated 12 / 09 / 2025, p. 102 / 556 96 / 264 in step (5010) until sending the N2 request (5012) to RAN 204. MM NAS service acceptance may include PDU session status in AMF 218. If this procedure (5000) is triggered only for signaling, MM NAS service acceptance may be sent to UE 202 after step (5006).

[00183] Next, (R)AN 204 and UE 202 can perform an RRC connection reconfiguration (600B) depending on the QoS information for all QoS flows of the enabled PDU sessions. If the service request procedure (5000) was triggered by a UE 202 in the CM-IDLE state, user plane security can be established in this step (600A). RAN 204 can forward the MM NAS service acceptance and the SM NAS Session Activation Acceptance to UE 202. If the service request procedure (5000) is triggered by a UE in the CM-IDLE state, UE 202 can remove the context of PDU sessions that are not available on CN 5G.

[00184] After the user plane radio resources are configured, uplink data from the UE can be forwarded (5014) to RAN 204. RAN 5G 204 can send the uplink data (5014) to the UPF address 212 and tunnel ID provided in step (5008). Then, (R)AN 204 can conditionally send to AMF 218 an N2 request ACK (5016) which includes N2 SM information (RAN tunnel information, a list of accepted QoS flows for each of the enabled PDU sessions and a list of rejected QoS flows for each of the enabled PDU sessions.

[00185] Next, AMF 218 can conditionally send an N11 (5018) message to SMF 220 that includes N2 SM information (RAN tunnel information), a RAT type, a list of accepted QoS flows, and a list of rejected QoS flows per accepted PDU session for SMF 220. If the EU 202 time zone has changed compared to the last reported EU time zone, then AMF 218 can include the time zone IE of Petition 870250082301, dated 12 / 09 / 2025, p. 103 / 556 97 / 264 UE in this message (5018). For rejected QoS flows, SMF 220 can send a request for SM NAS release QoS flows to UE 202. Message (5018) can include PDU session ID(s) and a list of rejected QoS flows for each PDU session. UE 202 can then confirm the release of rejected QoS flows. Optionally, if dynamic PCC is deployed, SMF 220 can initiate an IP-CAN session modification (4716) and provide new location information to PCF 222.

[00186] Next, SMF 220 can conditionally send UPF 212 an N4 session update request (4718) that includes RAN tunnel information and a list of accepted QoS flows. If a user plan needs to be configured or modified, SMF 220 can initiate an N4 session modification procedure and provide RAN tunnel information. UPF 212 can then conditionally send SMF 220 an N4 session update response (4720). Then, SMF 220 can conditionally send AMF 218 an N11 message ACK (e).

[00187] When the network needs to signal (e.g., N1 signaling to a UE 202, mobile-terminated SMS, PDU session radio resource establishment to deliver user data terminating in mobile) with a UE 202 in a CM-IDLE 5G state or a CM-CONNECTED 5G state, the network may initiate a network-triggered service request procedure. If the UE 202 is in the CM-IDLE 5G state, the network-triggered service request procedure may send a paging request to (R)AN 204 / UE 202. The paging request triggers the service request procedure on the UE 202. If the UE 202 is in CM-CONNECTED 5G mode, no paging request will be sent to (R)AN 204 / UE 202.

[00188] Figure 51 illustrates, in a message flowchart, an example of a service request procedure (5100), Petition 870250082301, dated 12 / 09 / 2025, page 104 / 556 98 / 264 according to an embodiment of the present invention. When UPF 212 receives downlink data in a PDU session and there is no AN 204 tunnel information stored in UPF 212 for the PDU session, UPF 212 can buffer the downlink data (e). UPF 212 can then send to SMF 220 a data notification (5104) that includes the PDU session ID, and priority. Upon arrival of the first downlink data packet, UPF 212 may send the Data Notification (5104) message to SMF 220. If UPF 212 receives additional downlink data packets for a QoS flow in the same PDU session with the same or lower priority than the first data notification (5104) sent, UPF 212 may buffer these downlink data packets and does not send a new data notification.If a Paging Policy Differentiation feature is supported by UPF 212 and is enabled by SMF 220 for that N4 session, UPF 212 may also include DSCP in the TOS (IPv4) / TC (IPv6) value of the downlink data packet's IP header. SMF 220 may send a Data Notification Acknowledgment (ACK) (5106) to UPF 212.

[00189] Next, SMF 220 can send an N11 (5108) message to AMF 218, including a permanent EU ID, a PDU session ID, and a priority. SMF 220 identifies AMF 218 and sends it an N11 (5108) message including the permanent EU ID, the PDU session ID, the priority, and a paging policy indication. The priority and PDU session ID can be set according to step (5104). If SMF 220, while waiting for the user plan to be established, receives an additional Data Notification message (5104) with a higher priority than the first N11 message (5108) sent, SMF 220 may send a new N11 message (5108) indicating the higher priority and PDU session ID to AMF 218. If SMF 220, while waiting for the Petition 870250082301, dated 12 / 09 / 2025, p. 105 / 556 If a 99 / 264 user plan is established and receives an N11 message from an AMF 218 different from the one that sent the N11 message (5108), the SMF 220 can resend the N11 message (5108) only to the new AMF 218 from which it received the N11 message. If the registration procedure with the AMF 218 change is in progress when the old AMF 218 receives the N11 message (5108), the old AMF 218 can reject the N11 message with an indication that the N11 message was temporarily rejected. When supporting Paging Policy Differentiation, the SMF 220 can indicate in the N11 message (5108) that the paging policy indication is related to the downlink data that triggered the Data Notification message.Note that AMF 218 may receive request message(s) from other network functions that lead to signaling to UE 202 / RAN 204, for example, network-initiated detachment, and SMF 220-initiated PDU session modification. If UE 202 is in the CM-CONNECTED 5G state and AMF 218 only delivers the N1 message to UE 202, the flow continues in step (5116) below.

[00190] AMF 218 can respond to SMF 220. If UE 202 is in CM-IDLE 5G state, and AMF 218 considers that UE 202 is not accessible for paging, AMF 218 can send a response (5110) to SMF 220, with cause code and information. SMF 220 can deliver this additional information to UPF 212. If UE 202 is in CM-CONNECTED 5G state, AMF 218 can send a response (5110) to SMF 220 indicating that UE 202 is in CM-CONNECTED 5G mode and then SMF 220 can execute steps (5010) to (5020) in the UE-triggered service request procedure (5000) to establish the radio resources and N3 tunnel of the PDU session. The remainder of this procedure is omitted.

[00191] If UE 202 is registered in AMF 218 and is in CM-IDLE 5G, but considered accessible for paging, AMF Petition 870250082301, dated 12 / 09 / 2025, p. 106 / 556 100 / 264 218 can send a paging message (5112) including a NAS ID for paging, a registration area, a paging DRX length, and a paging priority indication, for each (R)AN 204 node belonging to the registration area(s) where UE 202 is registered. By supporting Paging Policy Differentiation, AMF 218 can include paging policy indication in the paging request message (5112). Paging strategies can be configured in AMF 218 for different DNN combinations, paging policy indication, PDU session IDs from SMF 220 when available (see clause 4.9), and other PDU session context information identified by the PDU session ID received in the N11 message. Paging strategies may include a paging retransmission scheme (e.g., how often paging is repeated or at what time interval); determining whether to send the paging message to (R)AN 204 nodes during certain high AMF 218 load conditions; whether to apply sub-area-based paging (e.g., first page on the last known cell ID or TA and retransmission on all registered TAs).AMF 218 and (R)AN 204 can support further paging optimizations to reduce the signaling load and network resources used to successfully page a UE 202 by one or more of the following means: by AMF 218 implementing specific paging strategies (e.g., the N2 paging message is sent to the (R)AN 204 nodes that last served UE 202); by AMF 218 considering information about recommended cells and RAN nodes provided by (R)AN 204 in the transition to CN-IDLE. AMF 218 can take into account the (R)AN 204 node-related portion of this information to determine which (R)AN 204 nodes to page, and can provide the information on recommended cells within the N2 paging message for each of these (R)AN 204 nodes; and by (R)AN 204 considering count information. Petition 870250082301, dated 12 / 09 / 2025, p. 107 / 556 101 / 264 pagination attempts provided by AMF 218 in pagination. If EU radio capability for paging information is available in AMF 218, AMF 218 adds EU radio capability for paging information in the N2(e) paging message for (R)AN 204 nodes. If information about recommended cells and (R)AN 204 nodes for paging is available in AMF 218, AMF 218 may take this information into account to determine the (R)AN 204 nodes for paging and, when paging a (R)AN 204 node, AMF 218 may transparently transmit the information about the recommended cells for the (R)AN 204 node. AMF 218 may include paging attempt count information in the N2(5112) paging message(s). The paging attempt count information may be the same for all (R)AN 204 nodes selected by AMF 218 for paging.

[00192] Next, (R)AN node 204 can conditionally page (5114) UE 202. If (R)AN nodes 204 receive paging messages (5112) from AMF 218, UE 202 is paged (5224) by (R)AN node 204. When UE 202 is in CM-IDLE 5G state, after receiving a paging request, UE 202 can initiate the UE-triggered service request procedure (5000). In step (5008), AMF 218 can send an N11 message to the SMF(s) 220 associated with the PDU session identified by the PDU session ID(s) in the MM NAS service request message, and to the SMF(s) 220 from which it receives the N11 message in step (5006). AMF 218 supervises the paging procedure with a timer. If AMF 218 does not receive any response from UE 202 to the paging request message (5224), it can repeat the paging according to any applicable paging strategy described in step (5108).If AMF 218 does not receive any response from UE 202 after this re-paging procedure, AMF 218 can use the N11 message. Petition 870250082301, dated 12 / 09 / 2025, p. 108 / 556 102 / 264 to notify SMF 220 of the paging failure, if paging was triggered by an N11 message, unless AMF 218 is aware of an ongoing MM procedure that prevents UE 202 from responding (i.e., AMF 218 receives a context request message indicating that UE 202 is executing the TAU procedure with another AMF 218). When a downlink data notification rejection message is received, SMF 220 informs UPF 212, and UPF 212 discards the buffered packet(s). (5116) if the procedure is triggered due to a request from other network entities described in step (5108).

[00193] Figure 52A illustrates, in a state diagram, an example of a session management state model 5200A in a UE 202, according to an embodiment of the present invention. The session state can transition from a Session-IDLE state 610A to a Session-ACTIVE state 620A when a service request is accepted from AMF 218. The UE 202 session state can transition from the Session-ACTIVE state 620A to the Session-IDLE state 610A when the RRC is released.

[00194] Figure 52A further illustrates, in a state diagram, an example of a 5200A session management state model in a UE 202, according to embodiments of the present invention. When a new PDU session request is accepted, the PDU session status is created as part of the UE's PDU session context, and the PDU session status is set to the Session-ACTIVE state 620A. When the RRC is released, the PDU session status is set to the Session-IDLE state 610A. When the UE 202 sends a service request to transmit uplink data or to receive uplink data Petition 870250082301, dated 12 / 09 / 2025, page 109 / 556 103 / 264 descending, and UE 204 receives a Service Request Acceptance message from AMF 218, and the PDU session status is set to the ACTIVE Session state 620A.

[00195] Figure 52B illustrates, in a state diagram, an example of a session management state model 5200B in an AMF 218 and / or an SMF 220, according to an embodiment of the present invention. The session state can transition from a Session-IDLE state 610B to a Session-ACTIVE state 620B after session activation is complete. The session state can transition from the Session-ACTIVE state 620B to the SessionIDLE state 610B when the N2 connection is released.

[00196] The session state can be used to indicate that UE 202 has enabled a PDU session to send and receive data. Two session states include the Session-ACTIVE state and the Session-IDLE state. UE 202, AMF serving 218, and SMF serving 220 maintain the session state.

[00197] When a PDU session is in the Session-IDLE state, the UP data connection between UE 202 and the UPF 212 termination N3 connection is not established. UE 202 may not send or receive data. (R)AN 204 may not have the PDU session context. The UPF 212 termination N3 connection may have the UE PDU session context, but without (R)AN N3 204 connection information (i.e., without (R)AN 204 address and N3 Tunnel Endpoint Identifier). SMF 220 may maintain the UE PDU session context information relevant to SMF 220, but without the (R)AN 204 information. AMF 218 may maintain all relevant UE PDU session context information for AMF 218.

[00198] When a PDU session is in the SessionACTIVE state, UE 202 can send and receive data. The Uu air interface between UE 202 and (R)AN 204 can be established. The N3 connection can be established when the PDU session is activated. UE 202 can have all session context information. Petition 870250082301, dated 12 / 09 / 2025, page 110 / 556 104 / 264 PDU, including DRB information. AMF 218 can maintain all relevant UE PDU session context information for AMF 218. SMF 220 can maintain all relevant UE PDU session context information for SMF 220. (R)AN 204 can monitor the data activity of PDU sessions. An information element called “Last Data Activity Time” in the PDU session context on (R)AN 204 can be used to record the last time UE 202 had data activity. During a handover procedure, this information element can be transferred to the target (R)AN 204t and not modified as part of the UE context. Each PDU session context can also have a Session Inactive Timer. During the handover procedure, the (R)AN N3 204 connection information on the UPF 212 termination N3 connection can be updated if the PDU session has data activity.

[00199] Another parameter, “Status Flag N3, in the context of the UE PDU session on (R)AN 204 can be used to indicate whether the (R)AN 204 information on UPF 212 is up-to-date or not. The Status Flag N3 on (R)AN 204 can have two values: N3_AT_UPF_UPDATED and N3_NOT_AT_UPF_UPDATED. During the handover procedure, the target (R)AN 204 compares the duration during which UE 202 has no data activity (from the current time and the Last Data Activity Time parameter) and the Session Inactive Timer parameter. You can then conclude that UE 202 has data activity.When PDU session information is sent to (R)AN 204 during a session establishment procedure and a session request procedure, the N3 Status Flag on (R)AN 204 can be set. Petition 870250082301, dated 12 / 09 / 2025, p. 111 / 556 105 / 264 for N3_AT_UPF_UPDATED. The N3 Status Flag on (R)AN 204 can be changed from N3_AT_UPF_UPDATED to N3_AT_UPF_NOT_UPDATED during the handover procedure by the target (R)AN 204t if the PDU session has no data activity on a source (R)AN 204s. The N3 Status Flag on (R)AN 204 can be changed from N3_AT_UPF_NOT_UPDATED to N3_AT_UPF_UPDATED if the PDU session has data activity.

[00200] During a handover process, the target (R)AN 204t can send to AMF 218 a list of PDU sessions considered to have no data activity flagged by the target (R)AN 204t in the path switching request. The target (R)AN 204t can include another list of PDU sessions with the Status Flag N3 as N3_AT_UPF_NOT_UPDATED already set by the source (R)AN 204s. For each PDU session, the target RAN 204t can include the (R)AN 204 information of the PDU sessions, such as the (R)AN type, the (R)AN N3 address and the (R)AN N3 Tunnel Endpoint Identifier, and a list of accepted QoS flows and another list of rejected QoS flows. AMF 218 can store the (R)AN information. AMF 218 can inform the corresponding SMF serving 220 of the PDU session ID(s) that have no data activity tagged by the target (R)AN 204t in the path switching request.SMF 220 can send a message to UPF serving 212 to release tunnel information from (R)AN N3.

[00201] AMF 218 and SMF 220 may have an N3 Status Flag as part of their UE PDU session context. When the PDU session is established or activated, the N3 Status Flag in AMF 218 and SMF 220 may be set to N3_AT_UPF_UPDATED. The N3 Status Flag in AMF 218 and SMF 220 may be changed from N3_AT_UPF_UPDATED to N3_AT_UPF_NOT_UPDATED upon receiving the (R)AN 204 message indicating that this PDU Session has no data activity. The N3 Status Flag in AMF 218 and SMF 220 may be changed Petition 870250082301, dated 12 / 09 / 2025, p. 112 / 556 106 / 264 from N3_AT_UPF_NOT_UPDATED to N3_AT_UPF_UPDATED when UE 202 has data activity notified by UPF 212 or (R)AN 204.

[00202] Table 2 indicates the description of the session-ACTIVE and session-IDLE states for various network entities. • Network Entity • Session-ACTIVE • Session-IDLE • UE (maintains Session State) • Has all PDU session context, including DRB information • Has PDU session context without DRB information • (R)AN (does not maintain Session State) • Has all PDU session context and DRB information • Does not have PDU session context and no DRB information • UPF (does not maintain Session State) • Has all PDU session context information • Has PDU session context without (R)AN connection information N3 AMF (maintains Session State) Has all PDU session context information relevant for access and mobility management Has all PDU session context information relevant for access and mobility management SMF (maintains Session State) Has all PDU session context information.However, depending on the N3 Status Flag, the SMF may not have information about (R)AN without PDU session context, such as (R)AN type and information about. Petition 870250082301, dated 12 / 09 / 2025, p. 113 / 556 107 / 264 (R)AN, such as (R)AN type and (R)AN N3 connection information, if N3 Status Flag is N3_AT_UPF_NOT_UPDATE D . (R)AN N3 connection. Table 2: Session Status Description

[00203] Figure 52B further illustrates, in a state diagram, an example of a 5200B session management state model in an AMF 218 and / or an SMF 220, according to embodiments of the present invention. When a new PDU session request is accepted, the PDU session status is created as part of the UE PDU session context in the AMF 218 and SMF 220, and the PDU session status is set to the SessionACTIVE 620A state. When N2 is released, the PDU session status of all PDU sessions in the AMF 218 and SMF 220 transitions from the Session-ACTIVE 620A state to the Session-IDLE 610A state. When the UE 202 service request including the PDU Session Activation Request is accepted, the PDU session status of the requested PDU session transitions from the Session-IDLE state 610A to the Session-ACTIVE state 620A.

[00204] In 3GPP TS 23.502, clause 4.2.3.2, regarding UE-triggered service requests in the CM-IDLE state, a UE-triggered service request is described in the CM-IDLE state procedure. Step 5 of this procedure refers to AMF sending an N2 request message to (R)AN 204. Note that this message may include a Monitor Data Activity Flag in addition to N2 SM information received from SMF 220, a security context, an AMF Signaling Connection ID, a Handover Restrictions List, and a NAS MM Service Acceptance. (R)AN 204 stores the Security Context, Signaling Connection ID, and Petition 870250082301, dated 12 / 09 / 2025, p. 114 / 556 108 / 264 AMF, QoS information for QoS flows of PDU sessions that are activated, N3 Tunnel IDs, and the Monitor Data Activity Flag in the context of UE RAN.

[00205] An Xn-based inter-NG(R)AN handover can occur with and without UPF 212 relocation. The handover can be based on a centralized deployment or a local deployment. Separate call flows can be defined for roaming scenarios.

[00206] AMF 218 analyzes the UE 202 mobility pattern and determines, based on the mobility pattern, whether to request (R)AN 204 to monitor the data activity of individual PDU sessions. If AMF 218 requests (R)AN 204 to monitor the data activity of individual PDU sessions, after the PDU session is established or activated, (R)AN 204 will record the last time a PDU session has data activity through a parameter, such as a parameter called Last Data Activity Time. During the handover procedure, the Last Data Activity Time parameter is transferred to the target (R)AN 204t and not modified as part of the UE PDU context. The target (R)AN 204t sends the Last Data Activity Time parameter of the PDU sessions in the list of PDU sessions that require a path switch in the Path Switch request.

[00207] Alternatively, AMF 218 can inform SMF 220 about the EU mobility standard 202 during a session establishment procedure. SMF 220 can then determine whether to monitor the session data activity of individual PDUs. In this case, during the Session Establishment procedure, SMF 220 requests (R)AN 204 to monitor the PDU session data activity.

[00208] For each PDU session included in the path switching request, SMF 220 decides whether or not to update the (R)AN tunnel information for UPF 212 based on Petition 870250082301, dated 12 / 09 / 2025, page 115 / 556 109 / 264 criteria. The criteria may include at least one of: the UE 202 mobility pattern, a PDU session type, the time period during which the UE 202 has no data activity, and whether another PDU session is served by the same UPF 212. With the UE 202 mobility pattern, only the UE 202 requesting the handover is considered. The PDU session type may be stored as part of a PDU session's Attributes. The time during which the UE has no data activity is based on the Last Data Activity Time reported by (R)AN 204, as instructed by AMF 218.

[00209] AMF 218 and SMF 220 each have a parameter, called “N3 Connection Status”, as part of their UE PDU session context. The N3 Connection Status has two values: N3_CONNECTED and N3_DISCONNECTED. When the PDU session is established or activated, the N3 Connection Status on AMF 218 and SMF 220 is set to N3_CONNECTED. The N3 Connection Status of a PDU session on AMF 218 changes from N3_CONNECTED to N3_DISCONNECTED when AMF 218 receives a message from SMF 220 indicating that the (R)AN information is not up-to-date for this PDU session during the handover procedure. The N3 Connection Status of a PDU session on SMF 220 changes from N3_CONNECTED to N3_DISCONNECTED when SMF 220 decides not to update UPF 212 with (R)AN information during the handover procedure.The N3 Connection Status in AMF 218 and SMF 220 changes from N3_DISCONNECTED to N3_CONNECTED when UE 202 has data activity reported by UPF 212 or (R)AN 204.

[00210] During the handover process, the target (R)AN 204t sends to AMF 218 the list of PDU sessions to be switched and released in the path switching request. The PDU sessions to be switched are those that have UPF N3 tunnel information. For each PDU session to be switched, the target RAN 204t includes the Last Data Activity Time parameter, and the target (R)AN information, such as the Petition 870250082301, dated 12 / 09 / 2025, p. 116 / 556 110 / 264 type of (R)AN, the (R)AN address, and the N3 (R)AN Tunnel Endpoint Identifier. AMF 218 stores the type of (R)AN. AMF 218 informs the corresponding serving SMF 220 of the PDU session ID(s) to be switched and released. For PDU sessions to be switched, SMF 220 determines whether or not to update the (R)AN information to UPF 212. If SMF 220 determines to update the (R)AN information to UPF 212, SMF 220 sends N3 (R)AN tunnel information to UPF 212. If SMF 220 determines not to update the (R)AN information, SMF 220 sends a request message to UPF 212 to delete the N3 (R)AN tunnel information. SMF 220 informs AMF 218 of its decision to update or not update the (R)AN information on UPF 212. For PDU sessions where the (R)AN information is updated on UPF 212, the Connection Status N3 on AMF 218 and SMF 220 is set to N3_CONNECTED.Otherwise, the N3 Connection Status on AMF 218 and SMF 220 is set to N3_DISCONNECTED. During the N2 Release procedure, AMF 218 sends an N2 Release Notification message to the SMF(s) 220 that handle PDU sessions that are in the Session-ACTIVE state and have the N3 Connection Status set to N3_CONNECTED.

[00211] Figure 53 illustrates, in a message flowchart, an example of an Xn-based inter-NG RAN handover procedure (5300) without UPF 212 relocation, according to an embodiment of the present invention. This procedure (5300) can be used to transfer a UE 202 from a source RAN 204 to a target RAN 204t using Xn when AMF 218 is not changed and SMF 220 decides to maintain the existing UPF 212 (i.e., the UPF 212 that terminates the N3 interface in the NG Core Network (NGC)). The presence of IP connectivity between the source UPF 212 and the target UPF 212 is assumed.

[00212] The procedure (5300) includes handover preparation (5302) and handover execution (5304). Handover execution Petition 870250082301, dated 12 / 09 / 2025, p. 117 / 556 111 / 264 (5304) includes data routing (5306) from a source RAN 204s to a target RAN 204t. The target RAN 204t can check if some PDU sessions have an N3 Status Flag N3_AT_UPF_UPDATED, but have no data activity on the source RAN 204s, by reading the Last Data Activity Time parameter in the PDU session context. If the duration that a PDU has no data activity is greater than the Session Inactive Timer parameter, the PDU session will be considered to have no data activity. The target RAN 204t can send an N2 path switching request message (5308) to an AMF 218 to inform that UE 202 has moved to a new target cell, and a list of PDU sessions to be switched or removed, a list of PDU sessions that have no data activity marked by the target RAN 204t, and a list of PDU sessions that have no data activity marked by the source RAN 204s.Depending on the target cell type, the target RAN 204t may include appropriate information in this message (5308) for each PDU session, including the RAN type, the N3 RAN Address, and the N3 Tunnel Endpoint Identifier. If the target RAN 204t cannot support some QoS flows from a PDU session, the N2 path switching request message (5308) may include the list of accepted QoS flows and the list of rejected QoS flows for this PDU session.

[00213] Next, AMF 218 can send an N11 message (5310) to each SMF 220 associated with the PDU session lists received in the N2 path switching request (5308). For PDU sessions that require a path to be switched, after receiving the N11 message (5310), each of these SMFs 220 determines whether the existing UPF 212 can continue to serve UE 202. If the existing UPF 212 cannot continue to serve UE 202 and is not a PDU session anchor, steps (5608) to (5624) in Figure 56, as described below, are performed. Case Petition 870250082301, dated 12 / 09 / 2025, p. 118 / 556 112 / 264 otherwise, the following steps (5312) to (5318) are performed by each of these SMFs 220 if their existing UPFs 212 can continue to serve UE 202. For PDU sessions that are on the list of PDU sessions without data activity marked by the source RAN 204s and the list of PDU sessions without data activity marked by the target RAN 204t, AMF 218 can store the RAN 204 information. For each PDU session on the list of PDU sessions without data activity marked by the target RAN 204t, AMF 218 can send the N11 message (5310) to SMF 220 to forward the PDU Session ID to notify that the PDU session has no data activity.

[00214] Next, SMF 220 can initiate a release of PDU sessions that are not requested by target RAN 204t. For PDU sessions requested by target RAN 204t, SMF 220 can send an N4 session modification request (including RAN address, tunnel identifiers to the downlink user plane, list of accepted flows if present) (5312) to UPF 212. For PDU sessions where RAN 204 information must be released, SMF 220 can send an N4 session modification request (5312) to UPF 212 for these PDU sessions. The message (5312) can indicate the release of RAN N3 connection information (i.e., RAN address and tunnel identifier to the downlink user plane).Next, UPF 212 returns an N4 session modification response message (including tunnel identifiers for uplink traffic) (5314) to SMF 220 after the requested PDU sessions are switched or modified. In order to assist the reordering function on target RAN 204t for PDU sessions requiring a switched path, UPF 212 may send one or more “end marker” packets (5316) on the old path immediately after path switching. UPF 212 may begin sending downlink packets (5318) to target RAN 204t. Note this. Petition 870250082301, dated 12 / 09 / 2025, p. 119 / 556 113 / 264 the step (5318) can occur at any time after receiving the session modification response from N4 (5314) on SMF 2200. On SMF 220, for PDU sessions without data activity, the N3 Status Flag parameter of these PDU sessions can be changed from N3_AT_UPF_UPDATED to N3_AT_UPF_NOT_UPDATED. SMF 220 can send an N11 acknowledgment message (ACK) (5320) (including NC tunnel information) to AMF 212 for PDU sessions that have been successfully switched or modified.

[00215] After receiving the N11 (5320) message reply from SMFs 220, for PDU sessions with no data activity flagged by target RAN 204t, AMF 218 can change the N3 Status Flag parameter of these PDU sessions from N3_AT_UPF_UPDATED to N3_AT_UPF_NOT_UPDATED. Once the N11 (5320) message reply is received from all SMFs 220, AMF 218 can aggregate the CN tunnel information received from these replies and send this aggregated information as part of the N2 SM information in an N2 (5322) path switching request ACK to target RAN 204t. If none of the requested PDP sessions were successfully switched, AMF 218 may send an N2 path switching request failure message to target RAN 204t. On target RAN 204t, for PDU sessions with no data activity flagged by target RAN 204t, the N3 Status Flag parameter of those PDU sessions may be changed from N3_AT_UPF_UPDATED to N3_AT_UPF_NOT_UPDATED.When a Resource Release message (5324) is sent to the source RAN 204s, the target RAN 204t confirms the successful handover. It then triggers the resource release with the source RAN 204s.

[00216] Figure 53 further illustrates, in a message flowchart, an example of an Xn (5300) based interNG(R)AN handover procedure without user plane function relocation and with session deactivation, according to embodiments of the present invention. The procedure (5300) provides a solution Petition 870250082301, dated 12 / 09 / 2025, page 120 / 556 114 / 264 alternative that combines the handover procedure defined in clause 4.9.1.1 of TS 23.502 and the session disconnection signaling messages.

[00217] This procedure (5300) is used in a handover of a UE 202 from a source RAN 204s to a target RAN 204t using Xn when AMF 218 is unchanged and SMF 220 determines to maintain the existing UPF 212. UPF 212 is the UPF that terminates the N3 interface in the NGC. The presence of IP connectivity between the source UPF 212s and the target UPF 212t is assumed. When the PDU is established, SMF 220 sends a timer parameter to (R)AN 204, for example, called Session_Inactivity_Timer. The source (R)AN 204s logs the last time the PDU session had data activity using the Last Data Activity Time parameter. The source (R)AN 204s sends the Session_Inactivity_Timer parameter and the Last Data Activity Time parameter to the target (R)AN 204t as part of the UE PDU session context.If a PDU session has no data activity for a period longer than the Session_Inactivity_Timer parameter, the target (R)AN 204t will determine to initiate the PDU session shutdown procedure.

[00218] In the Handover Execution step, target (R)AN 204t sends UE 202 an RRC signaling message indicating whether PDU sessions are accepted, disabled, or rejected. Then, target (R)AN 204t informs SMF 220 (via AMF 218) that PDU sessions are accepted, disabled, or rejected. For accepted PDU sessions, target (R)AN 204t includes the N3 (R)AN tunnel information, such as the (R)AN address and Tunnel Endpoint Identifier. For PDU sessions that are accepted, SMF 220 requests UPF 212 to update the (R)AN tunnel information. For PDU sessions that are deactivated, SMF 220 sends a message requesting UPF 212 to delete the (R)AN tunnel information. For PDU sessions that are released, SMF 220 initiates the procedure of Petition 870250082301, dated 12 / 09 / 2025, p. 121 / 556 115 / 264 PDU Session Release.

[00219] Target RAN 204t sends an N2 Path Switching Request message (5308) to an AMF 218 indicating that UE 202 has moved to a new target cell. The message (5308) includes a list of PDU Sessions to be switched, deactivated, or removed. Depending on the target cell type, target RAN 204t includes other information in this message. The PDU sessions to be switched are the PDU sessions with N3 UPF tunnel information. For each PDU session to be switched, target (R)AN 204t includes the Last Data Activity Time parameter and the (R)AN information (such as the N3 AN address (R) and the N3 Tunnel Endpoint Identifier). If the target RAN 204t cannot support a QoS flow from a PDU session, the N2 Path Switching Request message (5308) will include the list of accepted QoS flows and the list of rejected QoS flows for this PDU session.

[00220] The AMF sends an N11 message (5310) to each SMF 220 associated with the list of PDU sessions received in the Path Switching Request message N2 (5308). For PDU sessions that require a path switch, after receiving the N11 Message (5310), each of these SMF 220s determines whether or not the existing UPF 212 can continue to serve UE 202. If the existing UPF 212 cannot continue to serve UE 202, and is not a PDU session anchor, steps 3-11 of clause 4.9.1.2 of the TS are executed 23.502. For each PDU session where a path switch is required, the SMF 220 determines whether or not the existing UPF 212 needs to be updated with tunnel information from (R)AN 204, according to clause 5.6. X of TS 23.501.

[00221] SMF 220 initiates the release of PDU Sessions that are not requested by the target RAN 204t. For PDU sessions requested by the target RAN 204t, SMF 220 sends an N4 Session Modification Request (6408) message to the UPF. Petition 870250082301, dated 12 / 09 / 2025, page 122 / 556 116 / 264 212. Message (5312) includes the (R)AN address, tunnel identifiers for the downlink user plane, and the list of accepted flows, if present. For PDU sessions to be deactivated, the (R)AN information does not need to be updated. SMF 220 sends an N4 Session Modification Request message (5312) to UPF 212 for these PDU sessions. Message (5312) indicates the release of N3 (R)AN tunnel information, such as the (R)AN address and Tunnel Endpoint Identifier for the downlink user plane. UPF 212 returns an N4 Session Modification Response message (5314) to SMF 220 after the requested PDU Sessions are switched or modified. Message (5314) includes tunnel identifiers for uplink traffic.

[00222] To assist the reordering function on target RAN 204t for PDU sessions requiring a path switch, UPF 212 sends one or more end marker packets (5316) on the old path immediately after the path switch. UPF 212 begins sending downlink packets to target RAN 204t. SMF 220 sends an N11 Message ACK message (5318) to AMF 218 for PDU sessions that have been successfully switched or disabled. The message (5318) includes NC Tunnel Information and indicates whether the N3 (R)AN tunnel information is updated (e.g., path switched) or deleted (e.g., PDU sessions disabled). In SMF 220, for PDU sessions where N3 (R)AN tunnel information is excluded from UPF 212, the session state is set to Session-IDLE. Note that step (5318) can occur at any time after receiving the N4 Session Modification Response message (5314) in SMF 220.

[00223] In AMF 218, upon receiving the ACK message from Message N11 (5318), the session state of disabled PDU sessions is set to Session-IDLE. As soon as the Message Response Petition 870250082301, dated 12 / 09 / 2025, p. 123 / 556 117 / 264 of N11 (5318) is received from all SMFs 220, AMF 218 aggregates CN Tunnel Information received from these responses and sends this aggregated information as part of the N2 SM Information in an N2 Path Switching Request ACK message (5320) to the target RAN 204t. The message (5320) includes an indication, for each PDU session, of whether or not UPF 212 is up-to-date with (R)AN information. If none of the requested PDP Sessions have been successfully switched, AMF 218 will send an N2 Path Switching Request Failure message to the target RAN 204t. On the target RAN 204t, for PDU sessions where UPF 212 is not up-to-date with (R)AN information, the N3 UPF tunnel information is deleted. When a Resource Release message (5322) is sent to the source RAN 204s, the target RAN 204t indicates successful handover. It then triggers resource release with the source RAN 204s.

[00224] Figure 53 further illustrates, in a message flowchart, an example of an Xn-based inter-NG (R)AN handover procedure (5300) without UPF 212 relocation, according to an embodiment of the present invention. This procedure (5300) can be used to transfer a UE 202 from a source (R)AN 204s to a target RAN 204t using Xn when AMF 218 is not changed and SMF 220 determines to maintain the existing UPF 212 (e.g., the UPF 212 that terminates the N3 interface in the NG Core Network (NGC)). The presence of IP connectivity between the source UPF 212 and the target UPF 212 is assumed.

[00225] Procedure (5300) includes handover preparation (5302) and handover execution (5304). Handover execution (5304) includes data routing (5306) from a source (R)AN 204s to a target (R)AN 204t. The target (R)AN 204t sends an N2 path switching request message (5308) to AMF 218 which includes an indication that UE 202 has moved to a new target cell, and a list of PDU sessions to be Petition 870250082301, dated 12 / 09 / 2025, p. 124 / 556 118 / 264 switched or removed. Depending on the target cell type, the target (R)AN 204t includes other information in the message (5308) for each PDU session to be switched, including the Last Data Activity Time parameter, and (R)AN information such as the N3 (R)AN Address and the N3 Tunnel Endpoint Identifier. If the target (R)AN 204t cannot support QoS flows from a PDU session, the N2 path switching request message (5308) may include the list of accepted QoS flows and the list of rejected QoS flows for this PDU session.

[00226] Next, AMF 218 sends an N11 message (5310) to each SMF 220 associated with the PDU session lists received in the Path Switching Request message N2 (5308). For PDU sessions that require a path switch, after receiving the N11 Message (5310), each of these SMFs 220 determines whether the existing UPF 212 can continue to serve UE 202. If the existing UPF 212 cannot continue to serve UE 202 and is not a PDU session anchor, steps (5608) to (5624) in Figure 56, as described below, are performed. Otherwise, the following steps (5312) to (5318) are performed by each of these SMFs 220 if their existing UPFs 212 can continue to service UE 202. For each PDU session where a path change is required, SMF 220 determines whether or not the existing UPF 212 should be updated with (R)AN tunnel information.

[00227] Next, SMF 220 initiates a release of PDU sessions that are not requested by the target RAN 204t. For PDU sessions requested by the target RAN 204t, SMF 220 sends an N4 session modification request message (5312) to UPF 212. The message (5312) includes the (R)AN address, tunnel identifiers for the downlink user plane, and a list of accepted flows, if present. For PDU sessions where the (R)AN 204 information is not needed, Petition 870250082301, dated 12 / 09 / 2025, p. 125 / 556 Updated 119 / 264, SMF 220 sends an N4 Session Modification Request message (5312) to UPF 212 for these PDU sessions. Message (5312) indicates the release of N3 RAN tunnel information, such as the (R)AN address and Tunnel Endpoint Identifier, to the downlink user plane. UPF 212 then returns an N4 Session Modification Response message (5314) to SMF 220 after the requested PDU sessions are switched or modified. Message (5314) includes tunnel identifiers for the uplink traffic. To assist the reordering function on target (R)AN 204t for PDU sessions that require a switched path, UPF 212 sends one or more “end marker” packets (5316) on the old path immediately after the path switch. UPF 212 can then start sending downlink packets (5318) to target RAN 204t.Note that step (5318) can occur at any time after receiving the N4 Session Modification Response message (5314) on SMF 2200. SMF 220 sends an N11 Message Acknowledgment (ACK) message (5318) to AMF 212 for PDU sessions that have been successfully switched or modified. Message (5318) includes CN tunnel information. Message (5318) indicates whether the N3 (R)AN tunnel information is updated (e.g., a path switch) or released (e.g., a path release). On SMF 220, for PDU sessions where the N3 (R)AN tunnel information is not updated on UPF 212, the N3 Connection Status parameter of those PDU sessions is changed from N3_CONNECTED to N3_DISCONNECTED.

[00228] On AMF 218, upon receiving the N11 Message ACK (5318), the N3 Connection Status parameter of PDU sessions, where SMF 220 does not update the (R)AN information for UPF 212, is changed from N3_CONNECTED to N3_DISCONNECTED. As soon as the N11 Message ACK (5318) is received from all SMFs 220, AMF 218 aggregates the NC tunnel information received from these. Petition 870250082301, dated 12 / 09 / 2025, p. 126 / 556 120 / 264 responses and sends this aggregated information as part of an N2 SM information in an N2 path switching request ACK (5320) to the target (R)AN 204t. The (5320) message includes an indication for each PDU session to know whether or not UPF 212 is up-to-date with (R)AN information. If none of the requested PDP sessions were successfully switched, AMF 218 sends an N2 path switching request failure message to the target (R)AN 204t. On the target (R)AN 204t, for PDU sessions where UPF 212 is not up-to-date with (R)AN information, the N3 UPF tunnel information is deleted. By sending a Resource Release message (5322) to the source (R)AN 204s, the target (R)AN 204t confirms the handover success. Next, it triggers the release of resources with the (R)AN originating from 204s.

[00229] Figure 53 further illustrates, in a message flowchart, an example of an Xn (5300) based interNG RAN handover procedure without User Plane function relocation, according to embodiments of the present invention. The target (R)AN 204 can send a Path Switching Request N2 (5308) message to an AMF 218 to inform that UE 202 has moved to a new target cell, and provide a list of PDU Sessions to be switched. Depending on the type of target cell, the target (R)AN 204t can include appropriate information in this message. For each one to be switched to the target (R)AN 204t, the Path Switching Request N2 (5308) message can include the list of accepted QoS flows.

[00230] AMF 218 can then send N2 SM information using an N11 message (5310) to each SMF 220 associated with the list of PDU sessions, and the list of accepted QoS flows for each PDU session, received in the N2 Path Switching Request (5308). For the PDU Sessions to be switched to the Target (R)AN 204t, after receiving the N11 Message, each of the SMF 220s determines whether the existing UPF 212 can continue to serve the Petition 870250082301, dated 12 / 09 / 2025, p. 127 / 556 121 / 264 UE 202. If the existing UPF 212 cannot continue to service UE 202 and is not a PDU session anchor, steps 3-11 of clause 4.9.1.2 TS. 23.502 are performed. Otherwise, the following steps will be executed. For the activated PDU session(s) that are not included in the N2 Path Switching Request message, AMF 218 may send separate request(s) to the relevant SMF(s) 220.

[00231] For PDU Sessions requested by target (R)AN 204t, SMF 220 can send an N4 Session Modification Request message (5312) to UPF 212. The message (5312) can include the (R)AN address, the tunnel identifiers for the Downlink User Plane, and the list of accepted QoS flows. For PDU Sessions that target (R)AN 204t cannot support, SMF 220 can determine whether to release or maintain, but not switch, this PDU session. If the PDU session is released, SMF 220 can initiate the PDU Session Release procedure. If the PDU session is maintained but should not be switched, SMF 220 can send an N4 session modification request (5312) to UPF 212 to set the PDU session's Session-AMBR to zero.

[00232] For a PDU session to be switched, UPF 212 may return an N4 Session Modification Response Message (5314) to SMF 212 after the requested PDU Sessions are switched. The message (5314) may include tunnel identifiers for uplink traffic. For the PDU session not to be switched, UPF 212 may return an N4 Session Modification Response Message (5314) accordingly.

[00233] For a PDU session to be switched, to assist the reordering function on the target (R)AN 204t, UPF 212 can send one or more end marker packets (5316) on the old path after switching the path. UPF 212 can then start sending downlink packets to the target (R)AN. Petition 870250082301, dated 12 / 09 / 2025, p. 128 / 556 122 / 264 204t.

[00234] SMF 220 can then send an N11 Message ACK (5318) to AMF 218 for PDU sessions that have been successfully switched. The message (5318) may include NC Tunnel Information. For a PDU session that has not been switched, SMF 220 can send an N11 Message ACK (5318) to (R)AN 204 via AMF 218. The message (5318) may include the N2 SM message which includes the PDU session ID and sets Session-AMBR to 0. Note that step (5318) can occur at any time after receiving the N4 Session Modification Response on SMF 220.

[00235] Once the N11 message response (5318) is received from all SMFs 220, AMF 218 can aggregate the CN tunnel information received from these responses and send the aggregated information as part of the N2 SM information in an N2 path switching request ACK (5320) to the target (R)AN 204t. If none of the requested PDP Sessions have been successfully switched, AMF 218 can send an N2 path switching request failure message (5320) to the target (R)AN. By sending a Resource Release message (5322) to the source (R)AN 204s, the target (R)AN 204t can confirm the successful handover. You can then trigger the resource release with the source (R)AN 204s.

[00236] In an Inter NG-RAN node handover without an Xn interface, a source (R)AN (S-RAN) 204s can initiate an N2-based handover to the target (R)AN (T-RAN) 204t. This can be triggered, for example, due to new radio or load balancing conditions, lack of Xn connectivity to the target (R)AN 204t, an error indication from the target (R)AN 204t after an unsuccessful Xn-based handover, or based on dynamic information learned by the S-RANs 204s.

[00237] Figure 54 illustrates, in a flowchart, an example of a method (5400) of transferring a UE 202 from a RAN of Petition 870250082301, dated 12 / 09 / 2025, p. 129 / 556 123 / 264 origin 204s to a target RAN 204t, according to the Xn-based inter-RAN handover procedure (5300) of Figure 53. The method (5400) can be executed by AMF 218. The method (5400) comprises AMF 218 configured to receive the path switching request message from N2 (5308) from target RAN 204t. Then, AMF 218 sends the N11 message (5310) to SMF 220. Then, AMF 218 receives the N11 message ACK (5318) from SMF 220. Then, AMF 218 sends the path switching request ACK message from N2 (5320) to target RAN 204t. Other steps can be added to the method (5400).

[00238] Figure 55 illustrates, in a flowchart, another example of a method (5500) of transferring a UE 202 from a source RAN 204s to a target RAN 204t, according to the Xn-based inter-NG RAN handover procedure (5300) of Figure 53. The method (5500) can be performed by SMF 220. The method (5500) comprises SMF 220 configured to receive the message from N1 (5310) from AMF 218. Then, SMF 220 sends the session modification request message from N4 (5312) to UPF 212. Next, SMF 220 receives the session modification response from N4 (5314) from UPF 212. Then, SMF sends the ACK message from N11 (5318) to the AMF 218. Other steps can be added to the method (5500).

[00239] Figure 56 illustrates, in a message flowchart, an example of an Xn-based interNG RAN handover procedure (5600) with user plane function relocation, according to an embodiment of the present invention. The procedure (5600) can be used to transfer a UE 202 from a source RAN 204s to a target RAN 204t using Xn when AMF 218 is not changed and SMF 220 decides that the source UPF 212s should be released. The source UPF 212s is the UPF 212 that terminates an N3 interface in the NGC. The presence of IP connectivity between the source UPF 212s and the source RAN is assumed. Petition 870250082301, dated 12 / 09 / 2025, p. 130 / 556 124 / 264 204s, and between the target UPF 212t and the target RAN 204t.

[00240] The procedure (5600) includes handover preparation (5302) and handover execution (5304). Handover execution (5304) includes forwarding data (5306) from a source RAN 204s to a target RAN 204t. The target RAN 204t can check if some PDU sessions have an N3 Status Flag N3_AT_UPF_UPDATED, but have no data activity on the source RAN 204s, by reading the Last Data Activity Time parameter in the PDU session context. If the duration that a PDU has no data activity is greater than the Session Inactive Timer parameter, the PDU session will be considered to have no data activity. The target RAN 204t can send downlink data (5602) to UE 202. UE 202 can send uplink data (5604).The target RAN 204t can send an N2 path switching request message (5308) to an AMF 218 to inform that UE 202 has moved to a new target cell, and a list of PDU sessions to be switched or removed, a list of PDU sessions that have no data activity marked by the target RAN 204t, and a list of PDU sessions that have no data activity marked by the source RAN 204s. Depending on the target cell type, the target RAN 204t can include appropriate information in this message (5308) for each PDU session, including the RAN type, the N3 RAN Address, and the N3 Tunnel Endpoint Identifier. If the target RAN 204t cannot support some QoS flows from a PDU session, the N2 path switching request message (5308) may include the list of accepted QoS flows and the list of rejected QoS flows for this PDU session.

[00241] Next, AMF 218 can send an N11 message (5310) to each SMF 220 associated with the PDU session lists received in the N2 path switching request (5308). For PDU sessions that require a path to be switched, Petition 870250082301, dated 12 / 09 / 2025, p. 131 / 556 125 / 264 after receiving the N11 message (5310), each of these SMFs 220 determines whether the existing UPF 212 can continue to serve UE 202. If the existing UPF 212 cannot continue to serve UE 202 and is not a PDU session anchor, steps (5606) to (5624) are executed, as described below. Otherwise, steps (5312) to (5318) in Figure 53, as described above, are executed by each of these SMFs 220 if their existing UPFs 212 can continue to serve UE 202. For PDU sessions that are in the list of PDU sessions with no data activity marked by the source RAN 204s and the list of PDU sessions with no data activity marked by the target RAN 204t, AMF 218 can store the RAN 204 information.For each PDU session in the list of PDU sessions without data activity marked by the target RAN 204t, AMF 218 can send the N11 (5310) message to SMF 220 to forward the PDU Session ID to notify that the PDU session has no data activity.

[00242] SMF 220 can initiate the release of PDU sessions that are not requested by target RAN 204t. SMF 220 can then select a new target UPF 212t (5606) based on the UPF Selection Criteria according to clause 6.3.3 of TS 23.501. The assignment of the target UPF 212t IP address and the allocation of downlink and uplink tunnel identifiers can be performed by SMF 220. An N4 session establishment request message (including the target RAN 204t address, uplink and downlink tunnel identifiers) (5608) can be sent to target UPF 212t. Target UPF 212t can send an N4 session establishment response message (5610) to SMF 220. SMF 220 can start a timer, to be used in step (5622) below. SMF 220 can send an N4 session modification request message (5612) to PDU session anchor 212a. PDU session anchor 212a can Petition 870250082301, dated 12 / 09 / 2025, p. 132 / 556 126 / 264 respond with an N4 session modification reply message (5614). At this point, PDU 212a session anchor can start sending downlink packets (5616) to target RAN 204t using the target RAN 204t address and tunnel identifiers via target UPF 212t. [002 43] SMF 22 0 can send an N11 (5618) message ACK (including CN tunnel information) to AMF 218. After receiving the N11 (5618) message reply from SMF 220, for PDU sessions with no data activity flagged by target RAN 204t, AMF 218 can change the N3 Status Flag parameter of those PDU sessions from N3_AT_UPF_UPDATED to N3_AT_UPF_NOT_UPDATED. Once the N11 message reply (5618) is received from all SMFs 220, AMF 218 can aggregate the CN tunnel information received from these replies and send this aggregated information as part of the N2 SM information in an N2 path switching request ACK (5320) to target RAN 204t. If none of the requested PDP sessions were successfully switched, AMF 218 can send an N2 path switching request failure message to target RAN 204t.In target RAN 204t, for PDU sessions without data activity flagged by target RAN 204t, the N3 Status Flag parameter of these PDU sessions can be changed from N3_AT_UPF_UPDATED to N3_AT_UPF_NOT_UPDATED. When sending a Resource Release message (5322) to source RAN 204s, target RAN 204t confirms the handover success. It then triggers resource release with source RAN 204s. UE 202 can now send uplink data (5620). Once the timer expires after the step (5610), SMF 220 can initiate a source UPF release procedure 212 by sending an N4 session termination request (5622) (including a release cause). The originating UPF 212s can confirm with an N4 session termination response message (5624) to confirm the release of resources. Petition 870250082301, dated 12 / 09 / 2025, page 133 / 556 127 / 264

[00244] Figure 56 further illustrates, in a message flowchart, an example of an Xn-based interNG (R)AN handover procedure (5600) with user plane function relocation, according to embodiments of the present invention. The procedure (5600) can be used to transfer a UE 202 from a source (R)AN 204s to a target (R)AN 204t using Xn when AMF 218 is not changed and SMF 220 determines that the source UPF 212s should be relocated. The source UPF 212s is the UPF 212 that terminates an N3 interface in the NGC. IP connectivity is assumed to exist between the source UPF 212s and the source RAN 204s, and between the target UPF 212t and the target RAN 204t.

[00245] The procedure (5600) includes handover preparation (5302) and handover execution (5304). Handover execution (5304) includes data routing (5306) from a source (R)AN 204s to a target (R)AN 204t. The target (R)AN 204t sends an N2 path switching request message (5308) to AMF 218 which includes an indication that UE 202 has moved to a new target cell and a list of PDU sessions to be switched or removed. Depending on the target cell type, the target (R)AN 204t includes other information in the message (5308) for each PDU session to be switched, including the Last Data Activity Time parameter and (R)AN information such as the N3 (R)AN Address and the N3 Tunnel Endpoint Identifier.If the target (R)AN 204t cannot support QoS flows from a PDU session, the N2 path switching request message (5308) may include the list of accepted QoS flows and the list of rejected QoS flows for this PDU session.

[00246] Next, AMF 218 sends an N11 message (5310) to each SMF 220 associated with the PDU session lists received in the Path Switching Request message N2 (5308). For PDU sessions requiring a path switch, after receiving the N11 Message (5310), each of these SMFs Petition 870250082301, dated 12 / 09 / 2025, page 134 / 556 128 / 264 220 determines whether the existing UPF 212 can continue to serve UE 202. If the existing UPF 212 cannot continue to serve UE 202 and is not a PDU session anchor, the following steps (7202608) to (5624) are executed. Otherwise, steps (5312) to (5318) in Figure 53, as described above, are executed by each of these SMFs 220 if their existing UPFs 212 can continue to serve UE 202. For each PDU session where a path exchange is required, SMF 220 determines whether the existing UPF 212 should be updated with (R)AN tunnel information.

[00247] SMF 220 initiates the release of PDU sessions that are not requested by target RAN 204t. For the PDU sessions to be switched, SMF 220 then selects a new target UPF 212t (5606) based on the UPF Selection Criteria according to clause 6.3.3 of TS 23.501. The assignment of the target UPF 212t IP address and allocation of downlink and uplink tunnel identifiers can be performed by SMF 220. SMF 220 sends an N4 Session Establishment Request message (5608) to target UPF 212t. The message (5608) includes the target RAN 204t address and the uplink and downlink tunnel identifiers. Target UPF 212t sends an N4 Session Establishment Response message (5610) to SMF 220. SMF 220 can start a timer, to be used in step (5590) below. SMF 220 sends an N4 Session Modification Request message (5550) to PDU session anchor 212a.The PDU 212a session anchor responds with an N4 session modification reply message (5614). At this point, the PDU 212a session anchor can begin sending downlink packets (5616) to the target RAN 204t using the target RAN 204t address and tunnel identifiers via the target UPF 212t.

[00248] SMF 220 sends an ACK message from N11 (5618) to Petition 870250082301, dated 12 / 09 / 2025, page 135 / 556 129 / 264 to AMF 218. Message (5618) includes NC tunnel information. On AMF 218, upon receiving the N11 Message ACK (5318), the N3 Connection Status parameter of PDU sessions, where SMF 220 does not update (R)AN information for UPF 212, is changed from N3_CONNECTED to N3_DISCONNECTED. Once the N11 Message ACK (5318) is received from all SMFs 220, AMF 218 aggregates the CN tunnel information received from these responses and sends this aggregated information as part of an N2 SM information in an N2 path switching request ACK (5320) to the target (R)AN 204t. Message (5320) includes an indication for each PDU session to know whether or not UPF 212 is up-to-date with (R)AN information. If none of the requested PDP sessions were successfully switched, AMF 218 sends a Path Switching Request Failure N2 message to target (R)AN 204t.In the target (R)AN 204t, for PDU sessions where UPF 212 is not updated with (R)AN information, the UPF N3 tunnel information is deleted. By sending a Resource Release message (5322) to the source (R)AN 204s, the target (R)AN 204t confirms the handover success. It then triggers the resource release with the source (R)AN 204s.

[00249] As soon as the timer expires after step (7302610), SMF 220 initiates a procedure to release source UPF 212 by sending an N4 Session Termination Request message (5622) to source UPF 212s. The message (5622) includes a release cause. Source UPF 212s acknowledges this with an N4 Session Termination Response message (5624) indicating resource release.

[00250] Figure 57 illustrates, in a message flowchart, an example of an N3 reconnection procedure (5700) triggered by UL data (i.e., a new UL data packet), according to an embodiment of the present invention. This procedure (5700) can be used to trigger an update. Petition 870250082301, dated 12 / 09 / 2025, p. 136 / 556 130 / 264 path switching for a PDU session that has Status Flag N3 as N3_AT_UPF_NOT_UPDATED on (R)AN 204 when uplink data arrives at (R)AN 204. UE 202 can send a UL data channel lease request or a UL data packet to (R)AN 204 (5702). If the PDU session N3 Status Flag is N3_AT_UPF_NOT_UPDATED, (R)AN 204 can send an N2 Message Path Switching Request (5704) to AMF 218. The message (5704) can include the PDU session ID (such as SUPI) and (R)AN information, including an (R)AN type, an N3 (R)AN address, and an N3 Tunnel Endpoint Identifier. Alternatively, the message (5704) can include only the PDU session ID.

[00251] AMF 218 can send a Message Path Switching Request from N11 (5706) to SMF 220 to forward the N2 message (5704) received from (R)AN 204. The message (5706) can also include an identifier to identify UE 202 (such as temporary ID 5G or SUPI), and (R)AN information (such as (R)AN type, (R)AN N3 Address and N3 Tunnel Endpoint Identifier). SMF 220 can send an N4 Message Session Modification Request (5708) to UPF 212. The message (5708) can include an identifier to identify UE 202 (such as temporary 5G ID or SUPI), the PDU session ID, tunnel (R)AN information (such as the N3 (R)AN address and the N3 Tunnel Endpoint Identifier). UPF 212 can update the (R)AN 204 information for the requested PDU session. UPF 212 can send an N4 Session Modification Response message (5710) to SMF 220.Message (5710) may include the UE identifier (such as SUPI) and the PDU Session ID. SMF 220 may change the PDU session N3 Status Flag to N3_AT_UPF_UPDATED. SMF 220 may send a Path Switching Response message N11 (5712) to AMF 218. Message (5712) may... Petition 870250082301, dated 12 / 09 / 2025, p. 137 / 556 131 / 264 include the UE identifier (such as SUPI) and the PDU Session ID. AMF 218 can change the PDU Session Status Flag N3 to N3_AT_UPF_UPDATED. AMF 218 can send a Path Switching Response message from N2 (5714) to (R)AN 204 to confirm that the path switching is complete. The message (5714) can include the PDU Session ID. (R)AN 204 can then send uplink data packets (5716).

[00252] Figure 57 further illustrates, in a message flowchart, an example of a delayed path switching procedure (5700) triggered by UL data without a UPF 212 relocation, according to embodiments of the present invention. This procedure (5700) can be used to trigger a path switching update for a PDU session that does not have UPF N3 tunnel information when (R)AN 204 receives the UL grant request or UL data for a PDU session. UPF 212 remains the same. SMF 220 stores the CN tunnel information. UE 202 sends a UL Data Channel Grant Request or a UL Data Packet to (R)AN 204 for a PDU session (5702). If the N3 UPF tunnel information is not available, (R)AN 204 sends an N2 Message Session Path Switching Request (5704) to AMF 218.Message (5704) includes the PDU session ID and (R)AN tunnel information, such as an N3 (R)AN address and an N3 Tunnel Endpoint Identifier.

[00253] AMF 218 sends a Message Session Path Switching Request N11 (5706) to SMF 220. The message (5706) includes an identifier to identify UE 202 (such as a SUPI and PDU Session ID), and (R)AN tunnel information (such as (R)AN type, (R)AN N3 address and Final Downlink Tunnel Point Identifier. Petition 870250082301, dated 12 / 09 / 2025, p. 138 / 556 If existing UPFs 212 can continue to serve UE 202 and is not a PDU session anchor, steps (4) to (9) of clause 4.9.1.c of TS 23.502 are executed. If existing UPFs 212 can continue to serve UE 202, SMF 220 sends a Message Session Modification Request N4 (5708) message to UPF 212. The (5708) message includes a UE identifier (such as a SUPI), the PDU session ID, and (R)AN N3 tunnel information such as the (R)AN N3 address and the N3 Tunnel Endpoint Identifier. UPF 212 updates the (R)AN 204 tunnel information for the requested PDU session. UPF 212 sends a Message N4 Session Modification Response (5710) to SMF 220. The message (5710) includes the SUPI and the PDU Session ID. SMF 220 sends a Message N11 Path Switching Response (5712) to AMF 218.Message (5712) includes the UE identifier (as a SUPI), the PDU session ID, and the N2 SM Message which includes the CN tunnel information for (R)AN 204. SMF 220 changes the N3 Connection Status of the PDU session to N3_CONNECTED. AMF 218 sends an N2 message path switching reply message (5714) to (R)AN 204 indicating that the path switching is complete. Message (5714) includes the PDU session ID(s) and the N2 SM message received from SMF 220. AMF 218 changes the N3 Connection Status of the PDU session to N3_CONNECTED. (R)AN 204 updates the CN tunnel information and sends uplink data packets (5716).

[00254] Figure 58 illustrates, in a message flowchart, an example of an N3 reconnection procedure (5800) triggered by DL data (i.e., a new DL data packet), according to an embodiment of the present invention. This procedure (5800) can be used to trigger a path switching update on UPF 212 for a PDU session that has the N3 Status Flag as N3_AT_UPF_NOT_UPDATED on SMF 220 when downlink data arrives at UPF 212. Petition 870250082301, dated 12 / 09 / 2025, p. 139 / 556 133 / 264 UPF 212 can receive downlink data packets from DN 208 (5802). UPF 212 can send DL message notification from N4 (5804) to SMF 220. The message (5804) can include an identifier to identify UE 202 (such as temporary 5G or SUPI) and a PDU session ID.

[00255] Based on the N3 Status Flag currently set to N3_AT_UPF_NOT_UPDATED, SMF 220 can send a Request for Information (R)AN message N11 (5806) to AMF 218. The message (5806) can include the UE Identifier (such as SUPI) and the PDU session ID. AMF 218 can change the PDU session N3 Status Flag to N3_AT_UPF_UPDATED. AMF 218 can send a Response Information (R)AN message N11 (5808) to SMF 220. The message (5808) includes a UE identifier (such as SUPI), the PDU session ID, and (R)AN information (including the (R)AN type, the (R)AN N3 address, and the (R)AN N3 Tunnel Endpoint Identifier). SMF 220 can send a Session Modification Request message N4 (5810) to UPF 212.Message (5810) may include an identifier to identify UE 202 (such as temporary ID 5G or SUPI), the PDU Session ID, (R)AN information (such as the (R)AN N3 address and the N3 Tunnel Endpoint Identifier). UPF 212 may update the (R)AN 204 information for the requested PDU session. UPF 212 may send an N4 Session Modification Response message (5812) to SMF 220. Message (5812) may include the UE identifier (such as SUPI) and the PDU Session ID. After receiving message (5690), SMF 220 may change the N3 Status Flag of the PDU session to N3_AT_UPF_UPDATED. UPF 212 can send downlink data packets (5814) to UE 202 via (R)AN 204. Note that step (5814) can be performed before step (5812).

[00256] In an alternative implementation of Figure 58, after receiving the message (5806), the AMF 218 can send a message Petition 870250082301, dated 12 / 09 / 2025, p. 140 / 556 134 / 264 of notification N2 to (R)AN 204 informing that UPF 212 is updated with (R)AN information. The message may include the PDU Session ID. (R)AN 204 may change the PDU Session Status Flag N3 to N3_AT_UPF_UPDATED. (R)AN 204 may send an N2 Notification Acknowledgment message to AMF 218 confirming receipt of the notification message from AMF 218.

[00257] In another alternative implementation of Figure 58, after receiving message (5812), SMF 220 can send an N2 message to (R)AN 204 via AMF 218 to notify (R)AN 204 that UPF 212 has updated (R)AN information. The message can include the PDU Session ID. After receiving this message, (R)AN 204 can change the PDU session Status Flag N3 to N3_AT_UPF_UPDATED.

[00258] (R)AN-CN interactions include procedures that belong to N2 interactions (e.g., NG2), for example, an N2 release procedure and potential procedures for an Inactive Connected RRC state.

[00259] An N2 Release procedure can be used to release the logical N2 signaling connection and all N3 connections to a UE 202. The procedure will transition UE 202 from a CN-CONNECTED state to a CN-IDLE state on both UE 202 and AMF 218. That is, the UE context on UE 202 and AMF 218 will be changed accordingly. All context information related to UE will be removed on (R)AN 204.

[00260] When an N2 signaling connection is lost, for example, due to loss of signaling transport or due to a (R)AN failure, the N2 release procedure can be performed locally by (R)AN 204 and AMF 218. When the N2 release procedure is performed locally by (R)AN 204 or AMF 218, each node locally performs its actions as described in the procedure flow below without using or relying on any signaling shown directly between the Petition 870250082301, dated 12 / 09 / 2025, page 141 / 556 135 / 264 (R)AN 204 and AMF 218. It should be noted that when the N2 signaling connection is lost due to an AMF 218 failure, it can be resolved by resolving the N2 viscosity and not result in an N2 release. The initiation of an N2 Release procedure can be initiated by (R)AN with a cause, or initiated by AMF with a cause. The cause of a procedure initiated by (R)AN can be at least one of an O&M Intervention, Unspecified Failure, User Inactivity, Repeated RRC Signaling Integrity Check Failure, a Release due to a UE-generated signaling connection release, Inter-RAT Redirection, etc. The cause of a procedure initiated by AMF can be at least one of an authentication failure, a detachment, etc.

[00261] The N2 Release procedure can be used to release an N2 connection and simultaneously disable PDU sessions when UE 202 enters the CM-IDLE state. Figure 59 illustrates, in a message flowchart, an example of a PDU Session Disable and N2 Release procedure (5900), according to embodiments of the present invention. The procedure (5900) can begin with (R)AN 204 and UE 202 executing an RRC Release procedure (5902). The RRC Release procedure (5902) can be similar to the RRC Release procedure (600A) described above. (R)AN 204 interacts with UE 202 to release the RRC signaling connection. UE 202 enters the CM-IDLE state and disables all PDU sessions. (R)AN 204 can send (N2 message) an N2 Release Request (5904) to AMF 218. The message (5904) can include a cause code, such as an O&M intervention, UE downtime, etc.Experts in the technique will appreciate that, in certain scenarios, step (5902) can be initiated before or in parallel with step (5904). AMF 218 can send (N11 message) an N2 Release Notification message (5906) to the SMF(s) 220 that signed the N2 Release Notification. The message (5906) Petition 870250082301, dated 12 / 09 / 2025, p. 142 / 556 136 / 264 may include a UE identifier (such as a SUPI), RAN information, and the cause code. It should be noted that SMF 220 may by default subscribe to an AMF 218 UE Mobility Event Notification service when the PDU session is established or activated. In this message, AMF 218 will notify SMF 220 of the N2 Release event. AMF 218 can track, or be aware of, the session state, i.e., whether the session is active or not. AMF 218 informs the SMF(s) 220 that it serves activated PDU sessions of the session state.

[00262] SMF 220 then sends (N4 message) an N3 Release Request (5908) to UPF(s) 212. The message (5908) may include PDU and UE SUPI Session ID(s) to be disabled. UPF 212 then releases the N3 (R)AN tunnel information (e.g., the (R)AN IP address and tunnel identifier) ​​in the UE PDU Session Context of PDU sessions to be disabled. UPF sends (N4 message) an N3 Release Reply (5910) to SMF 220 confirming the release of N3 (R)AN tunnel information. UPF 212 may begin buffering the downlink packets of the disabled PDU sessions. SMF 220 then sends (N11 message) a PDU Session Event Report Notification (5912) to AMF 218 to inform AMF 218 that the (R)AN tunnel information is deleted on UPF 212. This message (5912) is to acknowledge the N2 release notification message (5906).The SMF 220 can then change the session status from PDU to Session-IDLE.

[00263] AMF 218 then collects all SMF 220 responses that were reported in (5906). Once all SMF 220 acknowledgments are collected, and if step (5902) is not performed, AMF 218 sends (N2 message) an N2 Release Response (5914) to (R)AN 204 with a cause code. AMF 218 may change the session state of all UE 202 PDU sessions to Session-IDLE. If step Petition 870250082301, dated 12 / 09 / 2025, p. 143 / 556 137 / 264 (5902) was not performed, RAN 204 and UE 202 execute an RRC Release procedure (5916). The RRC Release procedure (5916) may be similar to the RRC Release procedure (600A) described above. (R)AN 204 sends a message to UE 202 to release the RRC connection. UE 202 enters the CM-IDLE state and all PDU sessions on UE 202 transition to the Session-IDLE state. Upon receiving confirmation of the RRC connection release from UE 202, (R)AN 204 removes the UE context. Next, (R)AN 204 sends (N2 message) an N2 Release Confirmation (5918) to AMF 218. Upon receiving the N2 Release Response message (5918), AMF 218 sets the UE Context to the CM-IDLE state and releases the N2 connection. It should be noted that AMF 218 may remove the subscription from the AMF 218 UE Mobility Event Notification service for SMF service PDU sessions(s).

[00264] In a modification to the embodiment described in relation to Figure 59, the N2 Release procedure can be used to release an N2 connection and simultaneously disable PDU sessions when UE 202 enters the CM-IDLE state. Figure 60 illustrates, in a message flowchart, another example of a PDU Session Disable and N2 Release procedure (6000), according to embodiments of the present invention. The procedure (6000) can begin with (R)AN 204 and UE 202 executing an RRC Release procedure (5902). The RRC Release procedure (5902) can be similar to the RRC Release procedure (600A) described above. (R)AN 204 interacts with UE 202 to release the RRC signaling connection. UE 202 enters the CM-IDLE state and disables all PDU sessions. (R)AN 204 can send (N2 message) an RRC Release Notification (5904) to AMF 218.Message (6002) may include a cause code, such as an O&M intervention, EU downtime, etc. Experts in the field will appreciate that, in certain scenarios, step (5902) may be initiated earlier. Petition 870250082301, dated 12 / 09 / 2025, p. 144 / 556 138 / 264 or in parallel with step (6002). AMF 218 can send (N11 message) an N2 Release Notification message (6004) to the SMF(s) 220 that signed the N2 Release Notification. The message (6204) can include a UE identifier (such as SUPI), RAN information, and cause code. Note that SMF 220 can sign an N2 Release Notification service by default when the PDU session is established or activated. AMF 218 can track, or otherwise be aware of, the session state, i.e., whether the session is active or not. AMF 218 informs the SMF(s) 220 that it serves activated PDU sessions of the session state.

[00265] SMF 220 then sends (N4 message) an N3 Release Request (6006) to UPF(s) 212. The message (6006) may include a UE identifier (such as SUPI) and PDU Session ID(s) to be disabled. UPF 212 then releases the N3 (R)AN tunnel information (e.g., the (R)AN IP address and Tunnel Endpoint Identifier) ​​in the UE PDU session context of PDU sessions to be disabled. UPF sends (N4 message) an N3 Release Reply (6008) to SMF 220 confirming the release of the N3 tunnel information. UPF 212 may begin buffering the downlink packets of the disabled PDU sessions. SMF 220 then sends (N11 message) an N2 Release Notification Acknowledgment message (6010) to AMF 218 which confirms the release notification message (6004). SMF 220 can then change the PDU session status to Session-IDLE.

[00266] AMF 218 then collects all SMF 220 responses that were reported in (6004). Once all SMF 220 acknowledgments are collected, and if step (5902) is not executed, AMF 218 sends (N2 message) an N2 Release Request message (6012) to (R)AN 204 with a cause code. AMF 218 changes the state of Petition 870250082301, dated 12 / 09 / 2025, p. 145 / 556 139 / 264 session of all PDU sessions from UE 202 to Session-IDLE. If step (5902) was not executed, (R)AN 204 and UE 202 execute an RRC Release procedure (5916). The RRC Release procedure (5916) may be similar to the RRC Release procedure (600A) described above. (R)AN 204 sends a message to UE 202 to release the RRC connection. UE 202 enters the CM-IDLE state and all PDU sessions on UE 202 transition to the Session-IDLE state. Upon receiving confirmation of RRC connection release from UE 202, RAN 204 removes the UE context. Next, (R)AN 204 sends (N2 message) an N2 Release Response (6014) to AMF 218. Upon receiving the N2 Release Response (6014) message, AMF 218 sets the UE context to the CM-IDLE state and releases the N2 connection.

[00267] A PDU session release requested by UE 202 or network for non-roaming and roaming with the local separation procedure can be used to release a PDU session when UE 202 is in the CM-CONNECTED state. Figure 61 illustrates, in a message flowchart, an example of a PDU session release procedure (6100) triggered by UE 202, PCF 222 or SMF 220, according to embodiments of the present invention. A trigger for the PDU session release procedure (6100) occurs when UE 202 sends to SMF 220 the message (SM Message of N1) UE Session Release Request message (6102). The message (6102) may include the PDU session ID. (R)AN 204 forwards the message over a logical interface, such as an N2 connection. AMF 218 checks the PDU session ID and forwards the message to SMF 220.The message forwarded from AMF 218 to SMF 220 includes a UE identifier (such as SUPI) and a PDU Session Release Request message from N1. Another trigger for the PDU session release procedure (6100) occurs when PCF 222 sends a message to SMF 220. Petition 870250082301, dated 12 / 09 / 2025, page 146 / 556 140 / 264 PCF Session Release Request message from N7 message (6104). Another trigger for the PDU session release procedure (6100) occurs when SMF 220 determines the release of PDU sessions by its own logic, or by receiving requests from at least one of UE 202, AN 204 (e.g., congestion report), DN 208, and UPF 212.

[00268] Once the PDU session release procedure (6100) is triggered, SMF 220 interacts with UPF 212 to release the PDU Context on UPF 212. SMF 220 sends a Session Release Request message of N4 message (6108) to UPF 212. The message (6108) may include at least one of a UE identifier (such as SUPI) and the PDU session ID. UPF 212 discards any remaining packets from the PDU session to be released and releases the PDU Context from the UE. UPF 212 then sends a Session Release Response (N4 message) message (6110) to SMF 220. If a dynamic policy is implemented, SMF 220 informs PCF 222 to execute a PDU-CAN Session Release procedure (6112) such that PCF 222 no longer provides session modification messages to SMF 220 belonging to the released PDU session. SMF 220 knows whether the session state is enabled or not.SMF 220 sends an N11 (6202) message to AMF 218, which includes a UE ID (e.g., a SUPI), an N1 SM PDU Session Release Request for UE 202, and an N2 SM PDU Session Release Request for (R)AN 204 if the PDU session was enabled. The N1 SM PDU Session Release Request message may include the PDU Session ID(s) and cause code(s). The N2 SM PDU Session Release Request message may include the PDU Session IDs. The N1 SM and N2 SM messages may be encapsulated in a container. SMF 220 can use a message transfer service from AMF 218, as defined in clause 5.2.2.4 of TS 23.502, to send N1 SM and N2 SM messages to UE 202 and (R)AN 204. Petition 870250082301, dated 12 / 09 / 2025, page 147 / 556 141 / 264

[00269] AMF 218 then transfers (6116) the message received from SMF 220 to (R)AN 204 through a logical interface, such as the N2 connection. If (R)AN 204 receives only the SM PDU N1 Session Release Request, (R)AN 204 forwards (6118) this message to UE 202. If (R)AN 204 receives both the N1 SM PDU Session Release Request and the N2 SM PDU Session Release Request, (R)AN 204 performs a Connection Reconfiguration (RRC) with UE 202. During this reconfiguration procedure, (R)AN 204 forwards the SM N1 message PDU Session Release Request to UE 202. (R)AN 204 and UE 202 release the radio resource(s) for the released PDU session(s). UE 202 and AN 204 release the PDU session context. If (R)AN 204 receives the N2 SM PDU Session Release Request in step (6224), (R)AN 204 sends an N2 SM PDU Session Release Response (6120) to SMF 220 via AMF 218.Message (6120) may include the PDU session ID(s). AMF 218 sends an N11 message (6122) to forward the SM PDU session response N2 to SMF 220. Message (6122) includes a UE identifier (such as a SUPI) and the SM PDU session response N2 received from (R)AN 204. After UE 202 receives the SM message N1's PDU Session Release Request in step (6118), UE 202 releases resources that serve released PDU sessions and eliminates the PDU session context. UE 202 sends the SM PDU Session Release Response N1 (6124) to SMF 220. The message includes the PDU session ID(s). (R)AN 204 transfers this message to AMF 218 via a logical interface, such as the N2 connection. AMF 218 sends a message from N11 to forward (6126) the session release response from N1 SM PDU received in step (6124) to SMF 220.The N11 message may include at least one UE identifier (such as a SUPI) and N1 SM PDU Session Release Response received in step (6122). After receiving messages in steps (6122). Petition 870250082301, dated 12 / 09 / 2025, page 148 / 556 142 / 264 and (6126), SMF 220 sends a Message N11 PDU Session Event Report Notification (62046128), as defined in Clause 5.2.8.1 of TS 23.502, to AMF 218 with the event trigger being a PDU session release. SMF 220 and AMF 218 exclude their PDU session context from the released PDU session.

[00270] As noted above, procedure (6100) can be used to perform a UE 202-triggered PDU session release. Alternatively, procedure (6100) can be used, with some modifications, as a network-requested PDU session release procedure for roaming and roaming with local separation to release a PDU session when UE 202 is in the CM-IDLE state. For example, if UE 202 is in the CM-IDLE state, AMF 218 will send a paging message to UE 202, carrying a notification to release the PDU session and the PDU session ID to be released. The remaining steps are similar to procedure (6100). For example, UE 202 sends an N1 SM PDU Session Release Request to SMF 220.

[00271] In a modification to the modality described in relation to Figure 61, a PDU session release requested by UE 202 or network for non-roaming and roaming with the local separation procedure can be used to release a PDU session when UE 202 is in the CM-CONNECTED state or the CM-IDLE state. SMF 220 may not be aware of the UE's connection management state, but it knows whether the PDU session is active or not. If UE 202 is in the CM-IDLE state, AMF 220 can send the PDU session status in AMF 218 to UE 202 for synchronization when the service request procedure occurs. Figure 62 illustrates, in a message flowchart, another example of a PDU session release procedure (6200) triggered by UE 202 or SMF 220, according to the present modalities. Petition 870250082301, dated 12 / 09 / 2025, page 149 / 556 143 / 264 invention. A trigger for the PDU session release procedure (6200) occurs when UE 202 sends the UE Session Release Request message (6102) to SMF 220 (SM Message from N1). The message (6102) may include the PDU session ID. (R)AN 204 forwards the message through a logical interface, such as an N2 connection. AMF 218 verifies the PDU session ID and forwards the message to SMF 220. The message forwarded from AMF 218 to SMF 220 includes a UE identifier (such as a SUPI) and a PDU Session Release Request message from N1. Another trigger for the PDU session release procedure (6200) occurs when PCF 222 sends SMF 220 a PCF Session Release Request from N7 message (6104).Another trigger for the PDU session release procedure (6100) occurs when SMF 220 decides to release PDU sessions by its own logic, or by receiving requests from UE 202, AN 204 (e.g., congestion report), DN 208, and UPF 212.

[00272] After the PDU session release procedure (62006200) is triggered, SMF 220 interacts with UPF 212 to release the PDU Context on UPF 212. SMF 220 sends an N4 Message Session Release Request (6108) to UPF 212. The message (6108) may include at least one of a UE identifier (such as a SUPI) and the PDU Session ID. UPF 212 discards any remaining packets from the PDU session to be released and releases the PDU Context from the UE. UPF 212 then sends a session release response (N4 message) (6110) to SMF 220. If a dynamic policy is implemented, SMF 220 informs PCF 222 to execute a PDU-CAN Session Release procedure (6112). SMF 220 knows whether the session state is enabled or not.SMF 220 sends an N11 Message Session Release Notification (6202) to AMF 218, which includes a UE ID (e.g., SUPI), an N1 SM PDU Session Release Request for UE 202, and a Request. Petition 870250082301, dated 12 / 09 / 2025, page 150 / 556 N1 SM PDU Session Release Request message 144 / 264 for (R)AN 204 if the PDU session has been activated. The N1 SM PDU Session Release Request message may include the PDU Session ID(s) and cause code(s). The N2 SM PDU Session Release Request message may include the PDU Session ID(s). N1 SM and N2 SM messages may be encapsulated in a container. SMF 220 may use an AMF 218 Message Transfer service to send N1 SM and N2 SM messages to UE 202 and (R)AN 204.

[00273] If the UE is in the CM-CONNECTED state, AMF 218 transfers (6116) the message received from SMF 220 to (R)AN 204 via a logical interface, such as the N2 connection. If (R)AN 204 receives only the SM PDU N1 Session Release Request, (R)AN 204 forwards (6118) this message to UE 202. If (R)AN 204 receives the N1 SM PDU Session Release Request and the N2 SM PDU Session Release Request, (R)AN 204 performs a Connection Reconfiguration (RRC) with UE 202. During this reconfiguration procedure, (R)AN 204 forwards the SM N1 message PDU Session Release Request to UE 202. (R)AN 204 and UE 202 release the radio resource(s) for the released PDU session(s). UE 202 and (R)AN 204 release the PDU session context.If (R)AN 204 receives the SM PDU N2 Session Release Request in step (6116), (R)AN 204 sends an SM PDU N2 Session Release Response (6120) to SMF 220 via AMF 218. The message (6120) may include the PDU session ID(s). AMF 218 sends an N11 message (6275) to forward the SM PDU N2 session response to SMF 220. The message (6275) includes the UE identifier (as a SUPI) and the SM PDU N2 session response received from (R)AN 204. If UE 202 receives the SM message N1 PDU Session Release Request in step (6118), then UE 202 releases the resources serving the released PDU sessions and deletes the . Petition 870250082301, dated 12 / 09 / 2025, p. 151 / 556 145 / 264 PDU session context. UE 202 sends the N1 SM PDU Session Release Response (6122) to SMF 220. The message includes the PDU Session ID(s). (R)AN 204 transfers this message to AMF 218 via a logical interface, such as the N2 connection. AMF 218 sends an N11 message to forward (6124) the N1 SM PDU Session Release Response received in step (6122) to SMF 220. The N11 message may include at least one UE identifier (such as a SUPI) and the N1 SM PDU Session Release Response received in step (6122). After receiving messages in steps (6275) and (6124), SMF 220 sends a Message N11 Session Release Confirmation (6204) to AMF 218. SMF 220 and AMF 218 remove their PDU session context from the released PDU session.

[00274] If UE 202 is in the CM-IDLE state, messages 6224, 6118, 6120, 6275, 6122, 6124, and 6204 are ignored. AMF 218 sends a Message N11 PDU Session Release Acknowledgment (6206) to SMF 220.

[00275] A Service Request procedure can be used by a 5G UE 202 in the CM-IDLE state to request the establishment of a secure connection with an AMF 218. The UE 202 in the CM-IDLE state can initiate the Service Request procedure to send uplink signaling messages, user data, or a response to a network paging request. After receiving the service request message, the AMF 218 can perform the authentication and security procedure. After establishing a secure signaling connection to an AMF 218, the UE 202 or network can send signaling messages, for example, establishing a PDU session from the UE 202 to the core network 206, or the SMF 220, through the AMF 220, can initiate the establishment of a user plane resource for the PDU sessions requested by the network and / or indicated in the service request message.

[00276] For any service request, AMF 218 can Petition 870250082301, dated 12 / 09 / 2025, page 152 / 556 146 / 264 respond with a Service Response message to synchronize the PDU session status between UE 202 and the core network 206. AMF 218 may also respond with a Service Rejection message to UE 202 if the service request cannot be accepted by the network. For a Service Request due to user data, a network may take further actions if a user plane resource establishment is unsuccessful. It should be noted that the service request procedure discussed in Figure 63 below is not applicable to an access network, such as a WiFi network, (once UE 202 is registered on the network) where UE 202 is always considered to be in the CM-CONNECTED state and where the user plane resource is always considered established for an active PDU session.

[00277] Figure 63 illustrates, in a message call diagram, an example of an Xn-based interNG (R)AN handover procedure (6300) without user plane function relocation and with session deactivation, according to embodiments of the present invention. The procedure (6300) combines the handover procedure defined in clause 4.9.1.1 of TS 23.502 and the session deactivation signaling messages. The procedure (6300) includes handover preparation (6302) and handover execution (6304). The handover execution (6304) includes data forwarding (6306) from a source (R)AN 204s to a target (R)AN 204t.

[00278] Target (R)AN 204t sends an N2 Path Switching Request message (6308) to an AMF 218 that includes an indication that UE 202 has moved to a new target cell, and a list of PDU Sessions to be switched or removed. Depending on the target cell type, target (R)AN 204t includes appropriate information in this message. The PDU sessions to be switched are the PDU sessions with N3 UPF tunnel information. For each PDU session to be switched, target (R)AN 204t Petition 870250082301, dated 12 / 09 / 2025, p. 153 / 556 147 / 264 includes the Last Data Activity Time parameter, and (R)AN information, such as the N3 (R)AN address and the N3 Tunnel Endpoint Identifier. If the target (R)AN 204t cannot support some QoS flows from a PDU session, the N2 Path Switching Request message (6308) will include the list of accepted QoS flows and the list of rejected QoS flows for this PDU session.

[00279] AMF 218 then sends an N11 Message (6310) to each SMF 220 associated with the list of PDU Sessions received in the Path Switching Request message N2 (6308). For PDU sessions that require a path switch, upon receiving the N11 Message (6310), each of the SMFs 220 determines whether the existing UPF 212 can continue to serve UE 202. If the existing UPF 212 cannot continue to serve UE 202, and is not a PDU session anchor, steps 3-11 of clause 4.9.1.2 of the TS are executed 23.502. Otherwise, the following steps (6312) to (6322) are performed by each of the SMFs 220 if their existing UPFs 212 can continue to serve UE 202. For each PDU session that path switching is required, SMF 220 determines whether or not to disable the session.

[00280] SMF 220 initiates the release of PDU Sessions that are not requested by the target (R)AN 204t. For PDU Sessions requested by the target (R)AN 204t, SMF 220 sends UPF 212 an N4 Session Modification Request (6312) including the (R)AN address, tunnel identifiers for the downlink user plane, and a list of flows if present. For PDU sessions to be deactivated, SMF 220 sends UPF 212 the N4 Session Modification Request message (6312) for those PDU sessions. The message (6312) indicates the release of N3 (R)AN tunnel information including the (R)AN address and a Tunnel Endpoint Identifier for the downlink user plane. UPF 212 returns a session modification response message from N4 (6314) to SMF 212 Petition 870250082301, dated 12 / 09 / 2025, p. 154 / 556 148 / 264 after the requested PDU sessions are switched or modified. Message (6314) includes tunnel identifiers for uplink traffic. To assist the reordering function on target (R)AN 204t for PDU sessions requiring a path switch, UPF 212 sends one or more end-of-path marker packets (6316) on the old path immediately after switching the path. UPF 212 begins sending downlink packets (6318) to target (R)AN 204t.

[00281] SMF 220 sends an N11 Message ACK (6320) to AMF 218 for PDU Sessions that have been successfully switched. The message (6320) includes CN Tunnel Information and indicates whether the (R)AN N3 tunnel information is updated (e.g., path switched) or deactivated (e.g., path released). The N11 Message ACK (6320) includes the N2 SM message, including PDU session ID(s), to (R)AN 204 to deactivate the PDU sessions. On SMF 220, for PDU sessions that are deactivated, the Session Status parameter is changed to Session-IDLE. Note that step (6320) can occur at any time after receiving the N4 session modification response message (6314) on SMF 220.

[00282] Upon receiving the N11 Message ACK (6320), AMF 218 sets the session state of PDU sessions accordingly. Once the N11 Message ACK (6320) response is received from all SMFs 220, AMF 218 aggregates the CN tunnel information received from these responses and sends this aggregated information as part of an N1 Message Session Disable request and N2 SM information (including PDU session ID(s) to be disabled) in the N2 Path Request ACK message (6322) to the target RAN 204t. If none of the requested PDP Sessions were successfully switched, AMF 218 sends a N2 Path Switching Request Failure message as message (6322) to the target (R)AN 204t. In the (R)AN target 204t, for the PDU sessions to be deactivated, the Petition 870250082301, dated 12 / 09 / 2025, pp. 155 / 556 149 / 264 UPF N3 tunnel information is deleted. (R)AN 204t forwards a Message Session Disable Request (6324) message from N1 to UE 202 in an RRC message. UE 202 sets the session state of the PDU sessions indicated in the N1 SM message to Session-IDLE. UE 202 releases the radio context of the disabled PDU sessions. UE 202 sends a Message Session Disable Response (6326) message from N1 to AMF 218 via target (R)AN 204t. By sending a Resource Release message (6328) to source RAN 204s, target (R)AN 204t confirms the successful handover. It then triggers the resource release with source RAN 204s.

[00283] Figure 64 illustrates, in a message flowchart, an example of a UE (6400) Triggered Service Request procedure, according to embodiments of the present invention. UE 202 can send to (R)AN 204 a NAS MM Service Request message (6402) that includes PDU session ID(s), security parameters, and a PDU session status. UE 202 sends a NAS message service request to AMF 218 encapsulated in an RRC message to RAN 204. If the service request is triggered for user data, UE 202 includes the PDU session ID in the NAS service request message (6402) to indicate the PDU session(s) that UE 202 is requesting to use. If the service request is triggered only for signaling, UE 202 does not need to include any PDU session ID.When this procedure (6400) is triggered for a paging response, if the UE 202 needs to use some PDU sessions, the UE 202 includes those PDU session ID(s) in the NAS MM Service Request message (6402). Otherwise, the UE 202 does not need to include any PDU session IDs. The PDU session status indicates the PDU sessions available on the UE 202. The PDU session status is included if the UE 202 has released some PDU sessions but has not reported AMF 218 when the UE 202 is in the CM-IDLE state. Petition 870250082301, dated 12 / 09 / 2025, page 156 / 556 150 / 264

[00284] (R)AN 204 then sends AMF 218 an N2 Message (6404) that includes MM NAS Service Request, a Temporary 5G ID, location information, a RAT type, and an RRC establishment reason. If AMF 218 is unable to handle the service request, it will be rejected. A Temporary 5G ID is obtained in an RRC procedure. RAN 204 selects AMF 218 according to this Temporary ID. The location information and RAT type refer to the cell in which UE 202 is encamped. Based on the PDU session status, AMF 218 can initiate the PDU session release procedure if the PDU session is unavailable on UE 202.

[00285] If the service request was not sent with integrity protection, or if the integrity protection is indicated as having failed, AMF 218 may initiate a NAS security / authentication procedure (6406). If UE 202 triggered the Service Request to establish only a signaling connection, then after the security exchange, UE 202 and the network may send signaling.

[00286] If the NAS MM Service Request message includes PDU session ID(s), or if this procedure (6400) is triggered by SMF 220, but the PDU session ID(s) from UE 202 correlate to other SMF 220s rather than the one triggering the procedure, AMF 218 sends an N11 message (6408) to the SMF 220(s) associated with the PDU session ID(s). After receiving the N11 message (6408), each SMF 220 sends an N11 message (6410) to AMF 218 to establish the user plan(s) for the PDU sessions. The message (6410) includes N2 SM information, such as a QoS profile, and NC N3 tunnel information. N2 SM information includes information that AMF 220 can provide to RAN 204.

[00287] AMF 218 can send to message (R)AN 204 the N2 Request (6412) which includes the N2 SM information received from SMF 220, a security context, an ID of Petition 870250082301, dated 12 / 09 / 2025, p. 157 / 556 151 / 264AMF Signaling Connection, a Handover Restrictions List, and an MM NAS Service Acceptance. RAN 204 stores the Security Context, AMF Signaling Connection ID, QoS Information for the QoS Flows of the PDU Sessions that are enabled, and N3 Tunnel IDs in the UE RAN context. The MM NAS Service Acceptance includes the PDU session status in AMF 218. The PDU session status is included if the core network has released some PDU sessions but has not informed UE 202 when UE 202 is in the CM-IDLE state. AMF 218 may include at least one N2 SM information element from SMF 220 if the procedure (6400) is triggered for PDU session user plane configuration. AMF 218 can send additional N2 SM information from SMFs 220, if any, in separate N2 messages, such as an N2 tunnel configuration request.Alternatively, if multiple SMFs 220 are involved, AMF 218 can send an N2 Request message to (R)AN 204 after all N11 messages from the SMFs 220 have been received. In such a scenario, the N2 Request message includes the N2 SM information received in each of the N11 messages, and information to allow AMF 218 to associate the responses with the relevant SMF 220.

[00288] (R)AN 204 can perform an RRC (6414) connection reconfiguration procedure with UE 202 depending on the QoS information for all QoS flows of the enabled PDU sessions and DRBs. User plane security is established at this stage. (R)AN 204 forwards MM NAS Service Acceptance to UE 202. UE 202 locally excludes the context of PDU sessions that are not available on CN 5G 206.

[00289] After the user plane radio resources are configured, the uplink data from UE 202 can now be forwarded (6416) to (R)AN 204. RAN 5G 204 sends the uplink data to UPF address 212 Petition 870250082301, dated 12 / 09 / 2025, page 158 / 556 152 / 264 and the Tunnel ID provided in steps (6408) and (6410). (R)AN 204 can send to AMF 218 an N2 Request ACK (6418) that includes N2 SM information, such as (R)AN tunnel information, the list of accepted QoS flows for enabled PDU sessions, and the list of rejected QoS flows for enabled PDU sessions. Message (6418) can include the N2 SM information element(s), for example, RAN tunnel information. (R)AN 204 can send the N2 SM information with separate N2 messages, such as an N2 tunnel configuration response, if AMF 224 sends separate N2 messages in step (6412). If multiple N2 SM information elements are included in the N2 Request message (6412), the N2 Request ACK (6418) may include multiple N2 SM information elements, and information to allow AMF 218 to associate responses to the relevant SMF 220.AMF 218 can send SMF an N11 message (6420) that includes N2 SM information, such as RAN tunnel information and RAT type, per accepted PDU session for SMF 220. If AMF 218 receives N2 SM information (one or multiple elements) in step (6418), then AMF 218 sends the N2 SM information to the relevant SMF 220. If the EU time zone has changed compared to the last reported EU time zone, then AMF 218 includes the EU Time Zone IE in this message (6420). If dynamic PCC is deployed, SMF 220 can optionally initiate an IP-CAN Session Modification (6422) and provide new location information to PCF 222.

[00290] SMF 220 can send UPF 212 an N4 Session Update Request message (6424) that includes RAN tunnel information. If a user plan needs to be configured or modified, SMF 220 initiates the N4 session modification procedure and provides the RAN tunnel information. UPF 212 can then send SMF 220 an N4 Session Update reply message (6426). SMF 220 can Petition 870250082301, dated 12 / 09 / 2025, page 159 / 556 153 / 264 then send to AMF an ACK message of Message N11 (6426).

[00291] A session state can be used to indicate that UE 202 has activated a PDU session to send and receive data. Two types of session states include an active state (sometimes called Session-ACTIVE state) and an idle state (sometimes called Session-IDLE state). UE 202, AMF serving 218, and SMF serving 220 can locally maintain the session state status.

[00292] When a PDU session is in the Session-IDLE state, the UP data connection between UE 202 and the UPF 212 termination N3 tunnel is not established. The UE does not send or receive data in the Session-IDLE state. (R)AN 204 does not have a PDU session context in the Session-IDLE state. The UPF 212 termination N3 connection has the UE's PDU session context, but no (R)AN N3 connection information (e.g., no (R)AN 204 IP address and no N3 Tunnel Endpoint Identifier). SMF 220 can store the relevant UE PDU session context information for SMF 220, but no (R)AN 204 information. AMF 218 can store all relevant UE PDU session context information for AMF 218.

[00293] When a PDU session is in the SessionACTIVE state, UE 202 can send and receive data. The Uu interface between UE 202 and (R)AN 204 is established in the SessionACTIVE state. The N3 connection is established when the PDU session is activated. UE 202 has access to all PDU session context information, including DRB information. AMF 218 stores all relevant UE PDU session context information for AMF 218. SMF 220 stores all relevant UE PDU session context information for SMF 220.

[00294] Table 3 provides a description of the SessionACTIVE and Session-IDLE states for various network entities. Network Entity Session-ACTIVE Session-IDLE Petition 870250082301, dated 12 / 09 / 2025, p. 160 / 556 154 / 264 UE 202 (maintains Session State) Has all session context information for AS PDUs and NAS Has session context information for AS PDUs and NAS without DRB information (R)AN 204 Has all session context information for PDUs. However, depending on UE data activity, (R)AN 204 may not have UPF N3 connection information Does not have PDU session context UPF 12 (does not maintain Session State) Has all session context information for PDUs. However, depending on data activity, UPF 12 may not have (R)AN N3 connection information Has PDU session context without (R)AN N3 connection information AMF 218 (maintains Session State and N3 Connection Status) Has all PDU session context information relevant for access management and Has all PDU session context information relevant for access management and Petition 870250082301, dated 12 / 09 / 2025, page 161 / 556 155 / 264 Mobility. Mobility. SMF 220 (maintains Session State and N3 Connection Status) Has all PDU session context information. However, depending on the N3 Status Flag, SMF 220 may not have (R)AN information if the Connection Status is N3_DISCONNECTED. Has PDU session context without (R)AN information.

[00295] Table 3: Session State Description

[00296] Figure 64 further illustrates, in a message flowchart, an example of a UE (6400) Triggered Service Request procedure in the CM-IDLE state, according to embodiments of the present invention. UE 202 can send to (R)AN 204 a NAS MM Service Request message (6402) that includes PDU session ID(s), security parameters, and a PDU session status. UE 202 can send a NAS message service request (6402) to AMF 218 encapsulated in an RRC message to RAN 204. The RRC message(s) can be used to carry the temporary 5G ID. If the service request is triggered for user data, the UE 202 can include the PDU session ID(s) in the NAS service request message (6402) to indicate the PDU session(s) that the UE 202 is requesting to use. If the service request is triggered only for signaling, the UE 202 does not need to include any PDU session IDs.When this procedure (6400) is triggered for a paging response, if UE 202 needs to use any PDU session(s), UE 202 can include that / those ID(s). Petition 870250082301, dated 12 / 09 / 2025, page 162 / 556 156 / 264 PDU session in the NAS MM Service Request message (6402). Otherwise, UE 202 does not need to include any PDU session ID. The PDU session status indicates the PDU sessions available in UE 202.

[00297] (R)AN 204 can then send AMF 218 an N2 (6404) message that includes an MM NAS service request, a temporary 5G ID, location information, a RAT type, and an RRC establishment reason. If AMF 218 is unable to handle the service request, it will be rejected. A temporary 5G ID is obtained in an RRC procedure. RAN 204 can select AMF 218 based on this temporary ID. The location information and RAT type refer to the cell in which UE 202 is camped. Based on the PDU session status, AMF 218 can initiate the PDU session release procedure if the PDU session is unavailable on UE 202.

[00298] If the service request was not sent with integrity protection, or if integrity protection is indicated as having failed, AMF 218 may initiate a NAS security / authentication procedure (6406). If UE 202 triggered the Service Request to establish only a signaling connection, then after the security exchange, UE 202 and the network may send signaling.

[00299] If the NAS MM Service Request message includes PDU session ID(s), or if this procedure (6400) is triggered by SMF 220, but the PDU session ID(s) from UE 202 correlate to other SMF 220s than the one triggering the procedure, AMF 218 sends an N11 message (6408) to the SMF 220(s) associated with the PDU session ID(s). After receiving the N11 message (6408), each SMF 220 sends an N11 message (6410) to AMF 218 to establish the user plan(s) for the PDU sessions. The message (6410) includes N2 SM information, such as a QoS profile and N3 CN tunnel information. N2 SM information includes information that Petition 870250082301, dated 12 / 09 / 2025, p. 163 / 556 157 / 264 to AMF 220 can supply RAN 204.

[00300] AMF 218 can send to message (R)AN 204 the N2 Request (6412) which includes the N2 SM information received from SMF 220, a security context, an AMF Signaling Connection ID, a Handover Restrictions List, and an MM NAS Service Acceptance. RAN 204 can store the Security Context, the AMF Signaling Connection ID, the QoS Information for the QoS Flows of the PDU Sessions that are activated, and the N3 Tunnel IDs in the UE RAN context. The MM NAS Service Acceptance includes the PDU session status on AMF 218. AMF 218 can include at least one N2 SM information element from SMF 220 if the procedure (6400) is triggered for PDU session user plane configuration. AMF 218 can send additional N2 SM information from SMFs 220, if any, in separate N2 message(s), such as an N2 tunnel configuration request.Alternatively, if multiple SMFs 220 are involved, AMF 218 can send an N2 Request message to (R)AN 204 after all N11 messages from the SMFs 220 have been received. In such a scenario, the N2 Request message includes the N2 SM information received in each of the N11 messages, and information to allow AMF 218 to associate responses to the relevant SMF 220.

[00301] (R)AN 204 can perform an RRC (6414) connection reconfiguration procedure with UE 202 depending on the QoS information for all QoS flows of the enabled PDU sessions and DRBs. User plane security is established at this stage. (R)AN 204 can forward the MM NAS Service Acceptance to UE 202. UE 202 can locally delete the context of PDU sessions that are not available on CN 5G 206. If (R)AN 204 accepts at least one of the QoS flows, UE 202 can store the enabled state of the PDU session. Otherwise, UE 202 considers the request. Petition 870250082301, dated 12 / 09 / 2025, p. 164 / 556 158 / 264 service as not accepted by (R)AN 204.

[00302] After the user plane radio resources are configured, uplink data from UE 202 can now be forwarded (6416) to (R)AN 204. RAN 5G 204 sends the uplink data to UPF address 212 and the Tunnel ID provided in steps (6408) and (6410). If (R)AN 204 accepts at least one QoS flow, the (R)AN 204 message can send to AMF 218 an N2 Request ACK (6418) that includes the N2 Rejection ACK (including the PDU Session ID, N2 SM Information, such as (R)AN tunnel information, the list of accepted QoS flows for enabled PDU sessions, and the list of rejected QoS flows for enabled PDU sessions). The message (6418) may include N2 SM information element(s), for example, RAN tunnel information.(R)AN 204 can send N2 SM information with separate N2 messages, such as an N2 tunnel configuration response, if AMF 224 sends separate N2 messages in step (6412). If multiple N2 SM information elements are included in the N2 Request message (6412), the N2 Request ACK (6418) can include multiple N2 SM information elements, and information to allow AMF 218 to associate the responses with the relevant SMF 220. If (R)AN 204 does not accept the PDU session, (R)AN 204 can send an N2 Request ACK message (6418) indicating to AMF 218 that the N2 SM Request is not Accepted and a cause code. The message (6418) may include the PDU Session ID, N2 SM information (including PDU Session Rejection, and the cause code).

[00303] AMF 218 can send an N11 message (6420) to SMF that includes the PDU Session ID, N2 SM information, such as RAN Tunnel information, and the RAT Type, per PDU Session accepted for SMF 220. If AMF 218 receives the N2 SM information (one or multiple elements) in step (6418), then AMF 218 forwards the N2 SM information to the relevant SMF 220. If Petition 870250082301, dated 12 / 09 / 2025, p. 165 / 556 If the EU time zone has changed compared to the last reported EU time zone, then AMF 218 includes the EU time zone IE in this message (6420). If the PDU session is accepted, and if dynamic PCC is deployed, SMF 220 can optionally initiate an IP-CAN Session Modification (6422) and provide new location information to PCF 222. SMF 220 can send UPF 212 an N4 Session Update Request message (6424) that includes RAN tunnel information. If a user plan needs to be configured or modified, SMF 220 initiates the N4 Session Modification procedure and provides the RAN tunnel information. UPF 212 can then send SMF 220 an N4 Session Update Response message (6426). SMF 220 can then send an N11 Message ACK (6426) to AMF. The message (6426) can include the PDU Session ID and the PDU session status.SMF 2225 can indicate the PDU session status (Enabled or Disabled) for AMF 218.

[00304] A Service Request triggered by a UE in CM-CONNECTED state can be used by a 5G UE 202 in CM-CONNECTED state to request the establishment of User Plan resources for PDU sessions. The network may perform other actions if the establishment of User Plan resources is unsuccessful. Note that the procedure shown in Figure 77 is not applicable to an access network (since the UE 202 is registered on the network) where the UE 202 is always considered to be in CM-CONNECTED state, and where the User Plan resource is always considered established for an active PDU session.

[00305] Figure 65 illustrates, in a message flowchart, an example of a delayed path switching procedure (6500) triggered by DL data without a UPF 212 relocation, according to embodiments of the present invention. This procedure (6500) can be used to trigger an update. Petition 870250082301, dated 12 / 09 / 2025, page 166 / 556 160 / 264 path switching occurs when DL data arrives at UPF 212 and UPF 212 lacks DL tunnel information. UPF 212 receives downlink data packets (6502) from DN 208. If (R)AN N3 tunnel information is unavailable, UPF 212 sends a Message DL Data Notification N4 (6504) message to SMF 220. The message (6504) includes a UE identifier (such as a SUPI) and a PDU session ID. SMF 220 sends a Message DL Data Notification N4 Acknowledgement (6506) message to UPF 212. Alternatively, the acknowledgment (6506) can be performed by a transport network messaging protocol.

[00306] If the N3 Connection Status is currently set to N3_DISCONNECTED, SMF 220 sends a Request for Information (R)AN Message N11 (6508) to AMF 218. Message (6508) includes a UE identifier (such as a SUPI), a PDU Session ID, and an N2 SM Message including CN tunnel information (such as UPF Address and N3 Tunnel Endpoint Identifier) ​​to (R)AN 204. AMF 218 sends a Path Switching Notification Message N2 (6510) to (R)AN, which includes the PDU Session ID and the N2 SM Message. (R)AN 204 updates the NC tunnel information. (R)AN 204 sends an N2 Message Path Switching Notification Acknowledgment (6512) message to AMF 218. The message (6512) includes a PDU Session ID and (R)AN tunnel information such as the (R)AN Address and Tunnel Endpoint Identifier.AMF 218 sends a Message (R)AN Information Response message from N11 (6514) to UPF 212. Message (6514) includes the UE identifier (as a SUPI), the PDU session ID, and the (R)AN tunnel information which includes the (R)AN type, the N3 (R)AN address, and the N3 Tunnel Endpoint Identifier. AMF 218 changes the N3 Connection Status of the PDU session to N3_CONNECTED. Petition 870250082301, dated 12 / 09 / 2025, p. 167 / 556 161 / 264

[00307] SMF 220 sends a Message N4 Session Modification Request (6516) to UPF 212. Message (6516) includes the UE identifier (as a SUPI), the PDU session ID, and N3 (R)AN tunnel information such as the N3 (R)AN address and the Downlink Tunnel Endpoint Identifier. UPF 212 updates the (R)AN tunnel information for the requested PDU session. UPF 212 sends a Message N4 Session Modification Response (6518) to SMF 220. Message (6518) includes a UE identifier and a PDU session ID. SMF 220 changes the N3 Connection Status of the PDU session to N3_CONNECTED. UPF 212 can send downlink data packets to UE 202 via (R)AN 204 before or after steps (6516) and (6518).

[00308] Figure 66 illustrates, in a message flowchart, an example of a delayed path switching procedure (6600) triggered by UL data with UPF 212 re-selection, according to embodiments of the present invention. This procedure (6600) can be used to trigger a path switching update when UE 202 requests the sending of UL data. UPF 212 may or may not be re-selected. This procedure (6600) can be separated into two procedures: one for a delayed path switching triggered by uplink data as defined in Figure 57, and one for a UPF 212 relocation, as defined in Figure 68.

[00309] UE 202 sends a UL data channel grant request message or a UL data packet (6602) to (R)AN 204 for a PDU session. If UPF N3 tunnel information is not available on (R)AN 204, (R)AN 204 sends the N2 Message Session Path Switching Request message (6604) to AMF 218. The message (6604) includes the PDU Session ID and (R)AN tunnel information, such as the (R)AN address and the (R)AN N3 Tunnel Endpoint Identifier. AMF then sends a Request message. Petition 870250082301, dated 12 / 09 / 2025, p. 168 / 556 162 / 264 Message Session Path Switching from N11 (6606) to SMF 220, including UE identifier (as a SUPI), PDU session ID, and (R)AN tunnel information such as (R)AN Type, (R)AN N3 address, and Downlink Tunnel Endpoint Identifier.

[00310] SMF 220 selects target UPF 212t to serve the PDU session based on the criteria of Clause 6.3.3 of TS 23.502 (6608). SMF 220 assigns N3 tunnel information, such as the N3 Tunnel Endpoint Identifier of the uplink. SMF 220 sends a Message Session Establishment Request N4 (6610) message to target UPF 212t. The message (6610) includes PDU Session ID, QoS policy, billing policy, and (R)AN tunnel information. The (R)AN tunnel information may include the (R)AN address, the Downlink Tunnel Endpoint Identifier, and the N3 and N9 Downlink Tunnel information such as the Anchor UPF address and the N9 Downlink Tunnel Endpoint Identifier. Target UPF 212t updates the (R)AN tunnel information and the Anchor UPF 212a tunnel information. Target UPF 212t sends an N4 Message Session Establishment Response (6612) message to SMF 220.The message (6612) includes the UE identifier (such as a SUPI) and the PDU session ID.

[00311] SMF 220 sends a Message Session Modification Request (6614) to anchor UPF 212a (as the anchor session UPF). Message (6614) includes the UE identifier (as a SUPI) and tunnel information from Target UPF N9, such as the target UPF address and the N9 uplink tunnel endpoint identifier. Anchor UPF 212a updates the target UPF tunnel information. Anchor UPF 212a sends a Message Session Modification Reply (6616) to SMF 220. SMF 220 sends a Message Session Path Switching Reply (6616) to SMF 220. Petition 870250082301, dated 12 / 09 / 2025, p. 169 / 556 163 / 264 (6618) for AMF 218. Message (6618) includes the UE identifier (as a SUPI), the PDU Session ID, and the N2 SM Message which includes the CN N3 Tunnel Information for (R)AN 204. SMF 220 changes the N3 Connection Status of the PDU session to N3_CONNECTED. SMF 220 starts a timer, to be used in step (6624).

[00312] AMF 218 sends a Message N2 Session Path Switching Response message (6620) to (R)AN 204 indicating that the path switching has been completed. Message (6620) includes the PDU Session ID, and the N2 SM Message received from SMF 220. AMF 218 changes the PDU session's N3 Connection Status to N3_CONNECTED. (R)AN 204 updates the CN tunnel information and sends uplink data packets (6622). Once the timer set in step (6618) expires, SMF 220 sends a Message N4 Session Termination Request message (6624) to the originating UPF 212s. Message (6624) includes the UE identifier (such as a SUPI) and the PDU session ID. The source UPF 212s deletes the PDU session context. The source UPF 212s sends an N4 Message Session Termination Response (6626) to SMF 220.

[00313] Figure 67 illustrates, in a message flowchart, an example of a delayed path switching procedure (6700) triggered by DL data with UPF 212 re-selection, according to embodiments of the present invention. This procedure (6700) can be used for a delayed path switching triggered by DL data arriving at UPF 212. First, the CN executes a path switching procedure without UPF 212 re-selection. After that, if the SMF 220 determines that UPF 212 needs to be relocated, the SMF 220 executes the UPF 212 re-selection procedure.

[00314] Anchor UPF 212a for the PDU session sends downlink data packets (6702) to source UPF 212s. Petition 870250082301, dated 12 / 09 / 2025, page 170 / 556 164 / 264 Next, steps (6504) to (6520) of the delayed path switching procedure (6500) triggered by DL data without UPF 212 re-selection are executed. SMF 212 selects a new UPF 212 (6704). If a new UPF 212 is selected (6704), a UPF 212 re-selection procedure (6800) is executed.

[00315] Figure 68 illustrates, in a message flowchart, an example of a UPF 212 re-selection procedure (6800), according to embodiments of the present invention. This procedure (6800) can be used to establish a new UPF 212 that terminates the N3 connection. The SMF 220 selects the target UPF 212t to serve the PDU session based on the criteria of Clause 6.3.3 of TS 23.502. The SMF 220 assigns N3 tunnel information (such as the N3 Tunnel Endpoint Identifier), and N9 tunnel information (such as the N9 Anchor UPF address and the N9 Uplink Tunnel Endpoint Identifier). SMF 220 sends a Message Session Establishment Request N4 (6802) message to the target UPF 212t. The message (6802) includes the PDU session ID, QoS policy, billing policy, and (R)AN tunnel information such as the (R)AN address, the Downlink Tunnel Endpoint Identifier, and N3 and N9 tunnel information.Target UPF 212t updates tunnel information for (R)AN, N3, and N9. Target UPF 212t sends an N4 Message Session Establishment Response (6804) message to SMF 220. The message (6804) includes the UE identifier (such as a SUPI) and the PDU session ID.

[00316] SMF 220 sends a Message Session Modification Request (6806) message to anchor UPF 212a (as the session anchor UPF). The message (6806) includes the UE identifier (as a SUPI) and the tunnel information of Target UPF N9, such as the Target UPF Address and the Downlink Tunnel Endpoint Identifier N9. Anchor UPF 212a Petition 870250082301, dated 12 / 09 / 2025, p. 171 / 556 165 / 264 updates the tunnel information of target UPF 212t. Anchor UPF 212a sends an N4 Message Session Modification reply message (6808) to SMF 220. Anchor UPF 212a can send downlink data (6810) to UE 202 via target UPF 212t. SMF 220 sends an N2 SM Message Session Modification Request (6812) message to (R)AN 204 using an AMF 218 message transfer service. The (6812) message to AMF 218 includes the UE identifier (such as a SUPI), and the N2 SM Message Session Modification Request to (R)AN 204 message includes the PDU Session ID and N3 tunnel information (such as UPF Address and Tunnel Endpoint Identifier). (R)AN 204 stores N3 tunnel information and sends an N2 SM Message Session Modification Reply (6814) message to SMF 220 via AMF 218. The (6814) message includes the PDU Session ID.AMF 218 adds the UE identifier (as a SUPI) and forwards the N2 SM Session Modification response message to SMF 220. UE 202 and (R)AN 204 can send UL (6816) data to target UPF 212t and anchor UPF 212a. SMF 220 sends an N4 Message Session Termination Request (6818) message to source UPF 212s. Source UPF 212s sends an N4 Message Session Termination Response (6820) message to SMF 220.

[00317] If an N2 UE Context Release Request is executed immediately after SMF 220 disables the PDU session, (R)AN 204 may release the N3 interface and the radio interface (including Uu) before UPF 212 receives instructions from SMF 220 to begin buffering downlink packets. It is thus possible that UPF 212 may forward some downlink packets to (R)AN 204, where (R)AN 204 does not have UE context information. Therefore, (R)AN 204 may discard these packets, which could lead to the loss of important information when the packets are... Petition 870250082301, dated 12 / 09 / 2025, page 172 / 556 166 / 264 dropped and / or incorrect billing, as UPF 212 is unaware that the packets were dropped. To avoid this situation, AMF 218 can collect all responses from SMF(s) 220 confirming that the session deactivation was completed before requesting (R)AN 204 to release the UE context.

[00318] Figure 69 illustrates, in a message flowchart, an example of a procedure for a UE context release in an AN (6900), according to embodiments of the present invention. This procedure (6900) can be used to release the logical N2-AP signaling connection (Application Protocol) and the associated N3 User Plane connections. When the N2-AP signaling connection is lost due to failure of (R)AN 204 or AMF 218, the UE context release in the AN (6900) procedure can be performed locally by AMF 218 or (R)AN 204 as described in the procedure flow below without using or relying on any signaling shown between (R)AN 204 and AMF 218. The UE context release in the AN (700) procedure can result in all UE 202 PDU sessions being disabled.

[00319] The start of the UE context release in the AN procedure (6900) can be initiated by (R)AN with a cause, for example, O and M Intervention, Unspecified Failure, AN Link Failure (e.g., Radio), User Inactivity, Release due to signaling connection release generated by UE (6902a), etc. The start of the procedure (6900) can also be initiated by AMF (6902b) with a cause, for example, Unspecified Failure, etc. Both the (R)AN initiated and AMF initiated steps of the UE context release in the AN procedure (6900) are shown in Figure 69.

[00320] If there are confirmed AN conditions (e.g., Radio Link Failure) or for other internal reasons of (R)AN 204, (R)AN 204 may initiate the UE context release in the AN procedure (6900). In this case, (R)AN 204 sends Petition 870250082301, dated 12 / 09 / 2025, p. 173 / 556 167 / 264 a Request for N2 UE Context Release (6902b) message for AMF 218. The message may include a Cause (or a cause code) that indicates (or represents) the reason for the release (e.g., Radio Link Failure, O&M intervention, unspecified failure, etc.). The initiation of a UE context release in the AN procedure (6900) may also be triggered by an internal AMF 218 event.

[00321] AMF 218 can send a message to each of the multiple activated PDU sessions serving SMF 220 to request the deactivation of those PDU sessions. For each of the activated PDU sessions serving SMF 220, AMF 218 can request SMF 220 to deactivate the PDU sessions: AMF 218 can send an N11 PDU session deactivation request message (6904) to SMF 220. The message (6904) can include a UE identifier (such as SUPI), an (R)AN identifier (such as (R)AN address), and a release cause (or cause code). AMF 218 can also store the deactivated state of the PDU session. Note that this step (6904) could also be via an AMF service: Namf_UE Mobility Event Notification (SMF).In this case, AMF 218 can send (via an N11 message) a UE Mobility Event Notification, indicating the N2 Release event, to the SMF(s) 220 serving active UE 202 PDU session(s) as defined in Clause 5.2.2.2 of TS 23.502. The message can include UE identifier (such as SUPI), (R)AN identifier information (such as (R)AN address), and cause code. The (R)AN identifier information can be used to distinguish between multiple (R)ANs in the event that a UE is connected to multiple (R)ANs.

[00322] Next, SMF 220 can send an N4 Session Modification Request message (6906a) to UPF 212. This message (6906a) may include AN tunnel information to be removed. Thus, SMF initiates a procedure of Petition 870250082301, dated 12 / 09 / 2025, p. 174 / 556 168 / 264 N4 session modification (6906a) indicating the need to remove AN tunnel information. A buffer command can indicate whether UPF 212 is to buffer an incoming DL PDU. Note that the request (6906a) includes a “buffer command”, then UPF 212 can initiate buffering of downlink PDUs received for UE 202, and initiate the “Network Triggered Service Request” procedure, described in clause 4.2.3.3 of TS 23.502, if a downlink PDU arrives for the PDU session. Then, UPF 212 can send the N4 Session Modification Response message (6906b) to SMF 220, acknowledging the SMF 220 request. SMF 220 can store the disabled state of the PDU session.

[00323] Next, SMF 220 can send to AMF 218 an N11 PDU session disable response message (6908). Note that this step (6908) could also be implemented using an SMF service: Nsmf_PDU Session Event Report Notification (AMF). SMF 220 can send (via an N11 message) a PDU session event report notification as defined in clause 5.2.8.1 of TS 23.502. The notification can include a UE identifier (such as a SUPI), PDU Session ID(s), and an event trigger (such as deletion of (R)AN tunnel information). After AMF 218 collects all PDU session deactivation response in step (6908) from SMF(s) 220 that was notified in step (6904), AMF 218 can send to (R)AN 204 a N2 UE Context Release Request message (6910).

[00324] If the AN connection (e.g., an RRC connection) to UE 202 has not yet been released (step 6902a), (R)AN 204 requests UE 202 to release the AN connection (6912). Upon receiving an acknowledgment of AN connection release from UE 202, (R)AN 204 can delete the UE context. (R)AN 204 can confirm the release of N2 by returning a message. Petition 870250082301, dated 12 / 09 / 2025, p. 175 / 556 169 / 264 of Complete N2 UE Context Release () (6914) for AMF 218. With this, the signaling connection between AMF 218 and (R)AN 204 for this UE 202 is released. Note that during this procedure, the AN may provide location information to AMF 218.

[00325] A PDU session release procedure can be used to release all resources associated with a PDU session. These resources may include the IP address / prefixes allocated to an IP-based PDU session, which may include the release of multiple prefixes in the case of multi-homing (as defined in TS 23.501). These resources may also include any UPF 212 resource (including N3 / N9 termination) that was used by the PDU session. SMF 220 may notify any entity associated with the PDU session of a PDU session release. These entities include PCF 222 and DN 208 (e.g., when DN 208 authorization occurred during PDU session establishment).

[00326] In some implementations, for disabled PDU sessions, SMF 220 may send an Asynchronous Session Release (ASR) flag and the PDU session ID to inform AMF 218 of a Session Release Request and to indicate whether or not the PDU session release procedure can be performed asynchronously. If the ASR flag is set to FALSE, the PDU session may be released immediately, regardless of the UE 202 CM state. If the ASR flag is set to TRUE, the PDU session release may be performed when UE 202 is in the CM-CONNECTED state. The ASR flag and PDU Session ID in the message from SMF 220 to AMF 218 may be included as follows: • For an activated PDU session, if UE 202 is in a CM-CONNECTED state, the PDU session can be released immediately. Therefore, SMF 220 does not need to send a Petition 870250082301, dated 12 / 09 / 2025, p. 176 / 556 170 / 264 ASR indication for AMF 218. • For a disabled PDU session, SMF 220 can send the ASR Flag and the PDU Session ID in the message to AMF 218. If the ASR Flag is set to FALSE, AMF 218 can send N1 SM Information (PDU Session Release Request) to UE 202 immediately. If UE 202 is in the CM-IDLE state, AMF 218 can page UE 202 to enter the CM-CONNECTED state. If UE 202 receives the paging, AMF 218 can send N1 SM Information (PDU Session Release Request) to UE 202. If UE 202 cannot receive the paging, AMF 218 can send a "non-delivery error message" to SMF 220, indicating the cause code (e.g., UE Unreachable). SMF 220 and AMF 218 can release the PDU session. The session state in AMF 218 and UE 202 can be synchronized when UE 202 executes a Service Request or Registration procedure.If the ASR flag is set to TRUE, the PDU session ...

Claims

1. A method characterized in that it comprises: sending, to an access and mobility management function (AMF) via an N2 interface, a path switching request message to inform that a UE has moved to a target cell served by the device, the path switching request message including a list of packet data unit (PDU) sessions to be switched and a list of accepted QoS flows, wherein accepted QoS flows are QoS flows that are accepted and not rejected by the RAN node; and receiving, from the AMF, an acknowledgment associated with the path switching request message.

2. A method according to claim 1, characterized in that it further comprises: before sending the path switching request message, receiving data from a source RAN node of a user equipment (UE) associated with PDU sessions in a handover procedure used to perform handover of the UE from the UE's source RAN node to the RAN node.

3. Method, characterized by comprising: receiving, from a radio access network (RAN) node via an N2 interface, a path switching request message to inform that a user equipment (UE) has moved to a target cell served by the RAN node, the path switching request message including a list of packet data unit (PDU) sessions to be switched and a list of accepted QoS flows for a PDU session in the list, wherein accepted QoS flows are QoS flows that are accepted and not rejected by the RAN node; and sending, to the RAN node, an acknowledgment associated with the path switching request message.

4. Method, according to claim 3, characterized in Petition 870250082301, dated 12 / 09 / 2025, page 272 / 556 2 / 10 by the fact that it further comprises: before sending the acknowledgment, sending, to a session management function (SMF), the received list of PDU sessions to trigger the SMF to determine whether an existing UP function (UPF) can continue to serve a UE associated with a PDU session in the list.

5. Method, according to claim 3 or 4, characterized in that it further comprises: receiving, from the SMF, a response acknowledging PDU sessions that have been successfully switched, wherein the acknowledgment associated with the path switching request message is sent to the RAN node after the device receives the response from the SMF.

6. A method according to any one of claims 3 to 5, characterized in that it further comprises: sending a resource release message to the UE's source RAN node to confirm the success of a UE handover from the UE's source RAN node to the RAN node and triggering a resource release with the UE's source RAN node.

7. Method for releasing an N2 connection associated with a user device (UD), characterized in that it comprises: receiving, by an access and mobility management function (AMF) from an access network (AN), a message including packet data unit (PDU) session identifiers (IDs) associated with the UED's PDU sessions; sending, by the AMF to a session management function (SMF), a PDU session deactivation request to deactivate a PDU session, the PDU session deactivation request including an identifier indicating the PDU session; receiving, by the AMF from the SMF, a PDU session deactivation response associated with the Petition 870250082301 request, dated 12 / 09 / 2025, page 1.273 / 556 3 / 10 PDU session deactivation; instruct the AMF to release a UE context from the UE after receiving the PDU session deactivation response; receive confirmation from the AN, via the AMF, of the release of the UE context; and release the N2 connection associated with the UE via the AMF.

8. Method, according to claim 7, characterized in that at least one of the messages received by the AMF and the PDU session deactivation request includes a cause code.

9. Method, according to claim 8, characterized in that the cause code indicates EU inactivity.

10. Method, according to any one of claims 7 to 9, characterized in that the session deactivation request includes a notification of N2 connection release.

11. A method, according to any one of claims 7 to 10, characterized in that sending the PDU session deactivation request comprises: sending, by the AMF, multiple PDU session deactivation requests to one or more SMFs, each of the multiple PDU session deactivation requests including an identifier indicating a corresponding PDU session; and receiving the PDU session deactivation response comprises: receiving, by the AMF from each of the one or more SMFs, one or more PDU session deactivation responses, each of which is a response to a corresponding PDU session deactivation request received.

12. Method, according to claim 11, characterized in that the AMF instructs the AN to release the EU context after receiving all responses associated with the PDU session deactivation requests that the AMF sent. Petition 870250082301, dated 12 / 09 / 2025, p. 274 / 556 4 / 10 13. Method, characterized by comprising: sending, to an access and mobility management function (AMF), a message including packet data unit (PDU) session identifiers (IDs) associated with the PDU sessions of a user device (UE), the message being to trigger a deactivation of the PDU sessions; in response to the message, receiving, from the AMF, an indication to release a UE context from the UE; sending, to the AMF, a confirmation of the release of the UE context; and releasing an N2 connection associated with the UE.

14. Method, according to claim 13, characterized in that the message sent to the AMF also includes a cause code.

15. Method, according to claim 14, characterized in that the cause code indicates EU inactivity.

16. Method, according to any one of claims 13 to 15, characterized in that the indication is received when one or more of the PDU sessions is deactivated.

17. A method characterized in that it comprises: obtaining, by a session management function (SMF), a trigger to release a packet data unit (PDU) session; sending, by the SMF, a session release request to a user plane function (UPF), the session release request including an identifier of the PDU session to be released, and requesting that the UPF discard any remaining packets from the PDU session and release contexts associated with the PDU session; and receiving, by the SMF from the UPF, a response indicating an acknowledgment of the session release request.

18. Method, according to claim 17, characterized in that: Petition 870250082301, dated 12 / 09 / 2025, page 275 / 556 5 / 10 when the PDU session is associated with multiple UPFs, the SMF sends the session release request to the multiple UPFs and receives from each of the multiple UPFs a respective response associated with the session release request.

19. Method, according to claim 17 or 18, characterized in that the method further comprises: determining, by the SMF, to release the PDU session; if a user device (UE) associated with the PDU session is inaccessible, notifying, by the SMF, an access and mobility management function (AMF) that the PDU session is released; and removing, by the SMF, a context associated with the PDU session.

20. Method, according to claim 19, characterized in that the SMF notifies the AMF that the PDU session is released by invoking an operation including a PDU session identifier.

21. A method according to claim 20, characterized in that a communication associated with the release of a resource between the AMF and the UE is ignored before the SMF removes the context.

22. A method, according to any one of claims 17 to 21, characterized in that the method further comprises: sending, by the SMF to an access and mobility management function (AMF), a request including a session management message (SM) from N1 to release the PDU session and an indication telling the AMF not to transfer the SM message from N1; and receiving, by the SMF from the AMF, a response indicating that the SM message from N1 is not transferred to the UE.

23. Method according to claim 22, characterized in that: the response is received when a user device (UE) Petition 870250082301, dated 12 / 09 / 2025, page 276 / 556 6 / 10 associated with the PDU session is in a connection management idle state (CM-IDLE).

24. Method according to claim 22 or 23, characterized in that: the SM message from N1 includes a PDU session release command.

25. A method characterized in that it comprises: receiving, by a user plane function (UPF) from a session management function (SMF), a session release request including an identifier of a packet data unit (PDU) session to be released; discarding, by the UPF, any remaining packets from the PDU session and releasing contexts associated with the PDU session; and sending, by the UPF to the SMF, a response indicating an acknowledgment of the session release request.

26. Method according to claim 25, characterized in that the UPF releases all tunnel resources associated with the PDU session when releasing the contexts associated with the PDU session.

27. Method, characterized in that it comprises: initiating, by a session management function (SMF), the release of a packet data unit (PDU) session; and if a user device (UE) associated with the PDU session is inaccessible, notifying, by the SMF, an access and mobility management function (AMF) that the PDU session is released.

28. Method according to claim 27, characterized in that: the SMF notifies the AMF that the PDU session is released by invoking an operation including information associated with the PDU session.

29. Method, according to claim 27 or 28, characterized in that the context is associated with at least one event subscription by SMF at AMF.

30. Method according to claim 29, characterized in that the method further comprises: removing, by SMF, a context associated with the PDU session, in which the communication associated with the release of the resource is ignored.

31. Method, characterized in that it comprises: receiving, by an access and mobility management function (AMF) from a session management function (SMF), a notification indicating that a packet data unit (PDU) session associated with an inaccessible user device (UE) is released; and removing, by the AMF, a context associated with the PDU session, in which a communication associated with the release of a resource is ignored, the resource being associated with the PDU session.

32. Method according to claim 31, characterized in that the AMF removes the context without the communication associated with the release of the resource.

33. Method, according to claim 31 or 32, characterized in that ignoring the communication associated with the release of the resource means that the AMF does not receive, from the SMF, N1 SM information, including a PDU session release command.

34. A method, according to any one of claims 31 to 33, characterized in that ignoring the communication associated with resource release comprises that the AMF does not perform at least one of the following steps: initiating a service request procedure to transmit N1 SM information to the UE that is in a CM-IDLE state; receiving an N2 SM resource release request from the SMF; transmitting the N2 SM resource release request and the N1 SM information to an access network node (AN); receiving an acknowledgment of the N2 SM resource release request from the AN node; and forwarding the acknowledgment of the N2 SM resource release request to the SMF.

35. A method, according to any one of claims 31 to 34, characterized in that the SMF initiates the release of the PDU session when deciding to release the PDU session based on at least one of a DN trigger, a UDM trigger, and a locally configured policy, and notifies the AMF that the PDU session is released by invoking an operation including information associated with the PDU session.

36. Method, according to any one of claims 31 to 35, characterized in that the context is associated with at least one event subscription by the SMF in the AMF.

37. Method, characterized in that it comprises: sending, by a session management function (SMF) to an access and mobility management function (AMF), a request including a session management N1 (SM) information requesting a user equipment (UE) to release a packet data unit (PDU) session and an ignore indication instructing the AMF to ignore transferring the N1 SM information to the UE; and if the UE is in a connection management idle state (CM-IDLE) and the ignore indication is received by the AMF, sending, by the AMF to the SMF, a response indicating that the N1 SM information is not transferred.

38. Method according to claim 37, characterized in that: the SM message from N1 includes a PDU session release command.

39. Method, according to claim 37 or 38, characterized in that the SMF requests that the UE release the PDU session by invoking a Petition operation 870250082301, dated 12 / 09 / 2025, page 279 / 556 9 / 10 Nsmf_Communication_N1MessageTransfer having an input that includes the N1 SM information and the indicator.

40. A method, according to any one of claims 37 to 39, characterized in that the SMF sends the N1 SM information if a user plane (UP) connection of the PDU session is disabled.

41. A method, according to any one of claims 37 to 40, characterized in that before sending the request, the method further comprises at least one of the following steps: the SMF decides to release the PDU session based on at least one request from a data network (DN), a request from a unified data management function (UDM), and a locally configured policy; and the SMF receives a trigger to release the PDU session from at least one UE and AMF.

42. Method, characterized in that it comprises: receiving, by an access and mobility management function (AMF) from a session management function (SMF), a request including session management N1 (SM) information to release a packet data unit (PDU) session associated with a user equipment (UE) and an ignore indication instructing the AMF to ignore the transfer of N1 SM information to the UE; the AMF then sends the N1 SM information to the UE in accordance with the ignore indication; and the AMF notifies the SMF of the undelivered N1 SM information.

43. Method according to claim 42, characterized in that, according to the ignore indication, the AMF discards the N1 SM information and refrains from transferring the N1 SM information to the EU.

44. Method according to claim 42 or 43, Petition 870250082301, dated 12 / 09 / 2025, p. 280 / 556 10 / 10 characterized in that: the N1 SM information is an N1 SM container including a PDU session release command.

45. Device comprising a processor coupled to a memory, characterized in that the processor is configured to execute a method as defined in any one of claims 1 to 44.

46. ​​System, characterized in that it comprises an apparatus, as defined in claim 45.

47. A non-transient processor-readable medium storing instructions, characterized in that, when executed by one or more processors, it causes one or more processors to perform a method, as defined in any one of claims 1 to 44.

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