System and method for handover

Abstract

Systems and methods for handover are provided. The first wireless communication node may select a first network entity for direct communication with the first wireless communication node. The first wireless communication node may send a packet data unit (PDU) session creation request message to the selected first network entity. The PDU session creation request message may include session management (SM) information and a session management function (SMF) address of the PDU session.

Description

Technical Field

[0001] This disclosure relates generally to wireless communications, including but not limited to systems and methods for handover. Background Technology

[0002] The standards organization Third Generation Partnership Project (3GPP) is currently working on developing a new radio interface called 5G New Radio (5G NR) and a next-generation packet core network (NG-CN or NGC). 5G NR will have three main components: the 5G Access Network (5G-AN), the 5G Core Network (5GC), and user equipment (UE). To facilitate the implementation of different data services and needs, the elements of the 5GC (also known as network functions) have been simplified so that some are software-based and some are hardware-based, allowing these elements to be adapted as needed. Summary of the Invention

[0003] The exemplary embodiments disclosed herein are intended to address problems related to one or more of the problems presented in the prior art, and provide additional features that will become apparent when taken in conjunction with the accompanying drawings and the following detailed description. Exemplary systems, methods, apparatuses, and computer program products are disclosed herein according to various embodiments. However, it should be understood that these embodiments are presented by way of example and not as limiting, and that various modifications can be made to the disclosed embodiments while remaining within the scope of this disclosure, as will be apparent to those skilled in the art upon reading this disclosure.

[0004] At least one aspect relates to a system, method, apparatus, or computer-readable medium in which a first wireless communication node (e.g., a target radio access network (RAN)) can select a first network entity (e.g., a session management function (SMF) or an intermediated SMF (I-SMF)) for direct communication with the first wireless communication node. The first wireless communication node can send a packet data unit (PDU) session creation request message to the selected first network entity. The PDU session creation request message may include session management (SM) information and the session management function (SMF) address of the PDU session. The SM information may include N2 SM information. The N2 SM information may include N3 user plane information of the PDU session.

[0005] In some embodiments, the first wireless communication node may receive a handover preparation request message from a second wireless communication node (e.g., the source RAN). The handover preparation request message may include at least one of the following: PDU session identity (ID); SMF address of the PDU session; Quality of Service (QoS) profile information of the PDU session; or radio resource information of the PDU session.

[0006] In some embodiments, the first wireless communication node may determine at least one radio resource reserved for the Quality of Service (QoS) flow of the PDU session. The first wireless communication node may send a handover preparation response message to the second wireless communication node, wherein the handover preparation response message includes information about the determined at least one radio resource.

[0007] In some embodiments, the first wireless communication node may receive a PDU session creation response corresponding to a session creation request message from a selected first network entity.

[0008] In some embodiments, the wireless communication device may perform a user equipment (UE) registration process via a first wireless communication node. The first wireless communication node may receive a PDU session establishment request message from the wireless communication device (e.g., the UE). The PDU session establishment request message may include at least one of the following: single-network slice selection assistance information (S-NSSAI); data network name (DNN); PDU session identifier (ID); or request type. Selecting a first network entity for direct communication with the first wireless communication node includes: the first wireless communication node determining the first network entity based on the PDU session establishment request message. The first wireless communication node transmits the PDU session establishment request message to the selected first network entity.

[0009] In some embodiments, the first wireless communication node may receive a resource request message from a selected first network entity, the resource request message being used to request the allocation of radio resources for at least one Quality of Service (QoS) stream corresponding to a PDU session establishment request message. The resource request message includes at least one QoS profile and N3 tunnel information for the user plane function (UPF).

[0010] In some embodiments, a first wireless communication node may receive a security mode command message from a second network entity (e.g., an Access and Mobility Management Function (AMF)). The security mode command message may include at least one security context for protecting communication between the wireless communication device (e.g., a UE) and the first wireless communication node. The first wireless communication node may transmit a registration request message to the second network entity (e.g., the Access and Mobility Management Function (AMF)). The registration request message may include at least one of the following: registration type; globally unique temporary identifier (GUTI); at least one security parameter; or UE mobility management (MM) core network capabilities. The second network entity may perform a UE authentication process based on the registration request message. Attached Figure Description

[0011] Various exemplary embodiments of the present solution are described in detail below with reference to the figures or accompanying drawings. The drawings are provided for illustrative purposes only and depict only exemplary embodiments of the present solution to aid the reader's understanding. Therefore, the drawings should not be considered as limitations on the breadth, scope, or applicability of the present solution. It should be noted that these drawings are not necessarily drawn to scale for clarity and ease of explanation.

[0012] Figure 1 An example cellular communication network that can implement the techniques disclosed herein is shown according to an embodiment of the present disclosure; Figure 2 Block diagrams of example base stations and user equipment according to some embodiments of the present disclosure are shown; Figure 3 An example architecture of a 5G system according to some embodiments of this disclosure is shown; Figure 4 A sequence diagram illustrating an example switching process according to some embodiments of the present disclosure is shown; Figure 5 A sequence diagram illustrating an example switching process according to some embodiments of the present disclosure is shown; Figure 6 A sequence diagram illustrating an example switching process according to some embodiments of the present disclosure is shown; Figure 7 A sequence diagram illustrating example switching processes according to some embodiments of the present disclosure is shown; and Figure 8 A flowchart of an example method for switching according to an embodiment of the present disclosure is shown. Detailed Implementation

[0013] 1. Mobile communication technology and environment Figure 1 An example wireless communication network and / or system 100 according to an embodiment of this disclosure is illustrated, in which the technologies disclosed herein can be implemented. In the following discussion, the wireless communication network 100 can be any wireless network, such as a cellular network or a narrowband Internet of Things (NB-IoT) network, and is referred to herein as network 100. Such an example network 100 includes base stations 102 (hereinafter referred to as "BS 102", also called wireless communication nodes) and user equipment 104 (hereinafter referred to as "UE 104", also called wireless communication devices) that can communicate with each other via communication links 110 (e.g., wireless communication channels), and a cluster of cells 126, 130, 132, 134, 136, 138, and 140 covering a geographic area 101. Figure 1In this context, BS 102 and UE 104 are included within the corresponding geographical boundaries of cell 126. Each of the other cells 130, 132, 134, 136, 138, and 140 may include at least one base station operating on its allocated bandwidth to provide sufficient radio coverage to the intended users of that cell.

[0014] For example, BS 102 can operate on the allocated channel transmission bandwidth to provide sufficient coverage to UE 104. BS 102 and UE 104 can communicate via downlink radio frame 118 and uplink radio frame 124, respectively. Each radio frame 118 / 124 can also be divided into subframes 120 / 127, which can include data symbols 122 / 128. In this disclosure, BS 102 and UE 104 are generally described herein as non-limiting examples of "communication nodes" capable of practicing the methods disclosed herein. According to various embodiments of this solution, such communication nodes may be capable of wireless and / or wired communication.

[0015] Figure 2 A block diagram of an example wireless communication system 200 for transmitting and receiving wireless communication signals (e.g., OFDM (orthogonal frequency division multiplexing) / OFDMA (orthogonal frequency division multiple access) signals) according to some embodiments of this solution is shown. System 200 may include components and elements configured to support known or conventional operating features that do not need to be described in detail herein. In one exemplary embodiment, system 200 may be configured to... Figure 1 The wireless communication environment 100 is a wireless communication environment in which communication (e.g., transmission and reception) data symbols are as described above.

[0016] System 200 generally includes base station 202 (hereinafter referred to as "BS 202") and user equipment 204 (hereinafter referred to as "UE 204"). BS 202 includes BS (base station) transceiver module 210 (hereinafter also referred to as transceiver module 210, transceiver 210 or base station transceiver 210), BS antenna 212 (hereinafter also referred to as antenna 212, downlink antenna 212 or RF antenna arrangement 212), BS processor module 214 (hereinafter also referred to as processor module 214), BS memory module 216 (hereinafter also referred to as memory module 216) and network communication module 218, each module being coupled and interconnected to each other as needed via data communication bus 220. UE 204 includes a UE (User Equipment) transceiver module 230 (hereinafter also referred to as UE transceiver 230, transceiver module 230, or transceiver 230), a UE antenna 232 (hereinafter also referred to as antenna 232, uplink antenna 232, or RF antenna arrangement 232), a UE memory module 234 (hereinafter also referred to as memory module 234), and a UE processor module 236 (hereinafter also referred to as processor module 236). Each module is coupled to and interconnected with each other as needed via a data communication bus 240. BS 202 communicates with UE 204 via a communication channel 250 (hereinafter also referred to as: wireless transmission link 250, wireless data communication link 250), which may be any wireless channel or other medium suitable for the data transmission described herein.

[0017] As those skilled in the art will understand, system 200 may also include, in addition to Figure 2 Any number of modules other than those shown herein. Those skilled in the art will understand that the various illustrative blocks, modules, circuits, and processing logic described in conjunction with the embodiments disclosed herein can be implemented in hardware, computer-readable software, firmware, or any practical combination thereof. To clearly illustrate this interchangeability and compatibility of hardware, firmware, and software, various illustrative components, blocks, modules, circuits, and steps are described generally according to their functionality. Whether this functionality is implemented as hardware, firmware, or software may depend on the specific application and design constraints imposed on the system as a whole. Those skilled in the art described herein can implement such functionality in a suitable manner for each specific application; however, such implementation decisions should not be construed as limiting the scope of this disclosure.

[0018] According to some embodiments, UE transceiver 230 may be referred to herein as an "uplink" transceiver 230 including a radio frequency (RF) transmitter and an RF receiver, each RF transmitter and RF receiver including circuitry coupled to antenna 232. A duplex switch (not shown) may alternatively couple the uplink transmitter or receiver to the uplink antenna in a time-division duplex manner. Similarly, according to some embodiments, BS transceiver 210 may be referred herein as a "downlink" transceiver 210 including an RF transmitter and an RF receiver, each RF transmitter and RF receiver including circuitry coupled to antenna 212. A downlink duplex switch may alternatively couple the downlink transmitter or receiver to downlink antenna 212 in a time-division duplex manner. The operation of the two transceiver modules 210 and 230 may be time-coordinated such that while the downlink transmitter is coupled to downlink antenna 212, the uplink receiver circuitry is coupled to uplink antenna 232 to receive transmissions via wireless transmission link 250. Conversely, the operation of the two transceivers 210 and 230 can be coordinated in time such that the downlink receiver is coupled to the downlink antenna 212 to receive transmissions on the wireless transmission link 250 while the uplink receiver is coupled to the uplink antenna 232. In some embodiments, there is tight time synchronization with a minimum guard time between changes in the duplex direction.

[0019] UE transceiver 230 and base transceiver 210 are configured to communicate via wireless data communication link 250 and cooperate with RF antenna arrangements 212 / 232 appropriately configured to support specific wireless communication protocols and modulation schemes. In some illustrative embodiments, UE transceiver 210 and base transceiver 210 are configured to support industry standards such as Long Term Evolution (LTE) and emerging 5G standards. However, it should be understood that this disclosure is not necessarily limited to application to specific standards and associated protocols. Rather, UE transceiver 230 and base transceiver 210 may be configured to support alternative or additional wireless data communication protocols (including future standards or variations thereof).

[0020] According to various embodiments, BS 202 may be, for example, an evolved Node B (eNB), a serving eNB, a target eNB, a femto station, or a pico station. In some embodiments, UE 204 may be embodied in various types of user equipment, such as mobile phones, smartphones, personal digital assistants (PDAs), tablets, laptops, wearable computing devices, etc. Processor modules 214 and 236 may be implemented or realized using the following devices designed to perform the functions described herein: general-purpose processors, content-addressable memory, digital signal processors, application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), any suitable programmable logic devices, discrete gate or transistor logic, discrete hardware components, or any combination thereof. In this way, the processor may be implemented as a microprocessor, a controller, a microcontroller, a state machine, etc. The processor may also be implemented as a combination of multiple computing devices, such as a combination of a digital signal processor and a microprocessor, a combination of multiple microprocessors, a combination of one or more microprocessors coupled with a digital signal processor core, or any other such configuration.

[0021] Furthermore, the steps of the methods or algorithms described in conjunction with the embodiments disclosed herein can be directly implemented in hardware, firmware, software modules executed by processor modules 214 and 236 respectively, or any practical combination thereof. Storage modules 216 and 234 can be implemented as random access memory (RAM), flash memory, read-only memory (ROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), registers, hard disks, removable disks, optical disc read-only memory (CD-ROM), or any other form of storage medium known in the art. In this respect, storage modules 216 and 234 can be coupled to processor modules 210 and 230 respectively, such that processor modules 210 and 230 can read information from and write information to storage modules 216 and 234 respectively. Storage modules 216 and 234 can also be integrated into their respective processor modules 210 and 230. In some embodiments, memory modules 216 and 234 may each include cache memory for storing temporary variables or other intermediate information during the execution of instructions to be executed by processor modules 210 and 230, respectively. Memory modules 216 and 234 may also each include non-volatile memory for storing instructions to be executed by processor modules 210 and 230, respectively.

[0022] Network communication module 218 broadly represents the hardware, software, firmware, processing logic, and / or other components of base station 202 that enable bidirectional communication between base station transceiver 210 and other network components and communication nodes configured to communicate with base station 202. For example, network communication module 218 may be configured to support Internet or WiMAX (World Interoperability for Microwave Access) services. In a typical but non-limiting deployment, network communication module 218 provides an 802.3 Ethernet interface, allowing base station transceiver 210 to communicate with traditional Ethernet-based computer networks. In this way, network communication module 218 may include a physical interface for connecting to a computer network (e.g., a Mobile Switching Center (MSC)). The terms “configured for,” “configured to,” and their various variations used in this document in relation to a specified operation or function refer to devices, components, circuits, structures, machines, signals, etc., that are physically constructed, programmed, formatted, and / or arranged to perform the specified operation or function.

[0023] The Open Systems Interconnection (OSI) model (referred to herein as the "OSI model") is a conceptual and logical layout that defines network communications used by systems (e.g., wireless communication devices, wireless communication nodes) for interconnecting and communicating with other systems. The model is divided into seven sub-components or layers, each representing a conceptual set of services provided to its upper and lower layers. The OSI model also defines logical networks and efficiently describes computer packet transmissions using different layer protocols. The OSI model may also be referred to as the seven-layer OSI model or the seven-layer model. In some embodiments, the first layer may be the physical layer. In some embodiments, the second layer may be the Medium Access Control (MAC) layer. In some embodiments, the third layer may be the Radio Link Control (RLC) layer. In some embodiments, the fourth layer may be the Packet Data Convergence Protocol (PDCP) layer. In some embodiments, the fifth layer may be the Radio Resource Control (RRC) layer. In some embodiments, the sixth layer may be a Non-Access Stratum (NAS) layer or an Internet Protocol (IP) layer, and the seventh layer may be any other layer.

[0024] Various exemplary embodiments of the present solution are described below with reference to the accompanying drawings to enable those skilled in the art to formulate and use the present solution. As will be apparent to those skilled in the art, various changes or modifications can be made to the examples described herein without departing from the scope of the present solution after reading this disclosure. Therefore, the present solution is not limited to the exemplary embodiments and applications described and illustrated herein. Furthermore, the specific order or hierarchy of the steps in the methods disclosed herein is merely illustrative. Based on design preferences, the specific order or hierarchy of the steps of the disclosed methods or processes can be rearranged while remaining within the scope of the present solution. Therefore, those skilled in the art will understand that the methods and techniques disclosed herein present various steps or actions in an exemplary order, and unless otherwise expressly stated, the present solution is not limited to the specific order or hierarchy presented.

[0025] 2. Systems and methods for switching In 5G systems, the access and mobility management function (AMF) relays session management messages between the user equipment (UE) and the session management function (SMF). This relaying can lead to inefficiency and excessive system complexity due to the interaction between the AMF and SMF. To simplify the interaction between the AMF and SMF in packet data unit (PDU) session management, this disclosure proposes a solution for PDU session handover that bypasses direct interaction between the AMF and SMF.

[0026] Figure 3 An example architecture of a 5G system according to some embodiments of this disclosure is shown. The following functionalities may be present in this example architecture.

[0027] (1) UE: User Equipment.

[0028] (2) RAN: Radio Access Network. The RAN manages radio resources. The RAN can transmit received user data to the UE through the N3 and can also transmit user data from the UE through the N3 interface. The RAN can perform mapping between the Dedicated Radio Bearer (DRB) and the Quality of Service (QoS) stream in the Packet Data Unit (PDU) session.

[0029] (3) AMF: Access and Mobility Management Function. This function may include at least one of the following: registration management, connection management, or reachability management and mobility management. This function may also perform access authentication and access authorization. The AMF may be a non-access stratum (NAS) secure terminal and may relay session management (SM) NAS messages between the UE and the session management function (SMF).

[0030] (4) SMF: Session Management Function. This function may include at least one of the following: session establishment, modification and release; UE IP address allocation and management (including optional authorization functions); selection and control of user plane (UP) functions, or downlink data notification. The SMF can control the user plane function (UPF) via N4 association. The SMF can provide the UPF with packet detection rules (PDR) to indicate how to detect user data services, forwarding action rules (FAR), QoS enforcement rules (QER), and usage reporting rules (URR) to indicate how the UPF should perform user data service forwarding, QoS processing and usage reporting for user data services detected by the PDR.

[0031] (5) UPF: User plane functions. These functions may include at least one of the following: serving as an anchor point for mobility within / between radio access technologies (RATs), packet routing and forwarding, service usage reporting, QoS processing for the user plane, or downlink packet buffering and downlink data notification triggering. The General Packet Radio Service (GPRS) tunneling protocol user plane (GTP) can be used between the RAN and UPF via the N3 interface. U) tunnel. GTP U-tunnels can be per PDU session. For downlink services, the UPF can bind the downlink service to the GTP of the PDU session by using the FAR received from the SMF. QoS flow within the U-tunnel. For uplink services, the RAN can transmit user plane services to a QoS flow identified by the UE.

[0032] (6) PCF: Policy control function (PCF). A PCF can provide QoS policy rules to control plane functions to enforce those rules. One or more PCFs can translate application function (AF) requests into policy and charging control (PCC) rules applied to PDU sessions.

[0033] (7) UDM: Unified Data Management (UDM). UDM can perform authentication and key management agreement (AKA) authentication credential generation, access authorization based on subscription data, and / or UE service network function (NF) registration management (e.g., storing AMF for UEs, storing SMF for UE PDU sessions), and subscription management. UDM can access the unified data repository (UDR) to retrieve UE subscription data and can store UE context in the UDR. UDM and UDR can be deployed together.

[0034] Figure 4 A sequence diagram of an example PDU session establishment process according to some embodiments of the present disclosure is shown.

[0035] Step 1: The UE may send a Non-Access Stratum (NAS) message (e.g., a PDU Session Establishment Request message) to the AMF. The NAS message may include at least one of the following: Single Network Slice Selection Auxiliary Information (S-NSSAI), Data Network Name (DNN), PDU Session Identifier (ID), Request Type, or N1 SM Container.

[0036] Step 2: The AMF can select a Session Management Function (SMF) for the PDU session via the network repository function (NRF) or locally configured. In the NRF case, the AMF can provide the NRF with a DNN and S-NSSAI, allowing the NRF to select an SMF for the AMF and provide the selected SMF's service area.

[0037] Step 3: The AMF can send an Nsmf_PDUSession_CreateSMContext (Nsmf_PDU session_createSM context) request message to the selected SMF. The Nsmf_PDUSession_CreateSMContext request message may include at least one of the following: PDU session ID, SM context ID, UE location information, access type, Radio Access Technology (RAT) type, or operation type.

[0038] Step 4: SMF can send an Nsmf_PDUSession_CreateSMContext response message to AMF.

[0039] Step 5: The SMF can determine that PCC authorization is required and request to establish an SM policy association with the PCF by calling the Npcf_SMPolicyControl_Create (Npcf_SMpolicyControl_Create) operation.

[0040] Step 6: The PCF can make authorization and policy decisions. The PCF can respond using the Npcf_SMPolicyControl_Create response message. In its response, the PCF can provide PCC rules to the SMF. The SMF can select a User Plane Function (UPF) and can request that the UPF to allocate an N3 tunnel for uplink data.

[0041] Step 7: The SMF can send a Namf_Communication_N1N2MessageTransfer message to the AMF. This message may include at least one of the following: parameters (e.g., PDU session ID), N2 SM information (e.g., PDU session ID, one or more QFIs (QoS Flow Identifiers), one or more QoS profiles, the N3 tunnel of the UPF), or N1 SM container (e.g., PDU session establishment acceptance).

[0042] Step 8: The AMF may send an N2 PDU session request message to the (R)AN. The N2 PDU session request message may include at least one of the following: N2 SM information, NAS message (e.g., PDU session ID, N1 SM container (e.g., PDU session establishment acceptance)).

[0043] Step 9: The (R)AN can send RRC reconfiguration to the UE. The (R)AN can publish access network (AN) specific signaling exchanged with the UE, which is related to information received from the SMF. For example, in the case of NG-RAN (Next Generation Radio Access Network), RRC connection reconfiguration can occur when the UE establishes NG-RAN resources associated with one or more QoS profiles. The (R)AN can also allocate (R)AN tunnel information for PDU sessions. The (R)AN can forward NAS messages to the UE (e.g., PDU session ID, N1 SM container (e.g., PDU session establishment acceptance)).

[0044] Step 10: The (R)AN can send an N2 PDU session response message (e.g., PDU session ID, reason, N2 SM information) to the AMF. The (R)AN tunnel information can correspond to the access network address of the N3 tunnel corresponding to the PDU session.

[0045] Step 11: The AMF can send an Nsmf_PDUSession_UpdateSMContext (Nsmf_PDU session_updateSM context) request (e.g., SM context ID, N2 SM information, request type) message to the SMF. The AMF can forward the N2 SM information received from (R)AN to the SMF.

[0046] Step 12: SMF can send an Nsmf_PDUSession_UpdateSMContext response (reason) message to AMF.

[0047] exist Figure 4 During the process, both SM NAS messages (e.g., PDU session establishment request, PDU session establishment acceptance) and N2 SM information can be transmitted via AMF, which may be inefficient. This disclosure provides a solution for handling PDU sessions without AMF involvement. This disclosure also provides a solution for the Xn-based handover process, where there is no interaction between AMF and SMF.

[0048] Example of implementation method 1 In this disclosure, the RAN can communicate directly with the SMF without the AMF's involvement. This is possible when the N2 interface is service-based; thus, the RAN can discover the SMF via the Network Repository Function (NRF) and communicate directly with the selected SMF. Figure 5 A sequence diagram of an example UE registration process according to some embodiments of this disclosure is shown. During this process, the AMF provides security information to the RAN to protect messages between the UE and the RAN.

[0049] Step 1: The UE can send a NAS registration request message to the RAN. The NAS registration request message may include at least one of the following: registration type, globally unique temporary identifier (GUTI), at least one security parameter, UE mobility management (MM) core network capability, or other parameters.

[0050] Step 2: The RAN can select an AMF and can forward the registration request message to the AMF.

[0051] Step 3: The AMF can decide to retrieve the UE context, including the subscription permanent identifier (SUPI), from the older AMF. The AMF can send a UE context request message to the older AMF identified by the GUTI provided by the UE.

[0052] Step 4: The old AMF can return the UE context, including SUPI, to the new AMF.

[0053] Step 5: The AMF can perform the UE authentication process. During this process, the UE can be authenticated by the network, and the network can also be authenticated by the UE.

[0054] Step 6: After successful UE authentication, the AMF can send a security mode command message to the RAN node. This message may include a security context to protect messages between the UE and the RAN.

[0055] Step 7: The RAN can send a security mode command to the UE to initiate security processing. The UE can respond to the RAN's security protections using NAS message security mode completion. These security protections can include both message integrity and message encryption.

[0056] Step 8: The RAN can decrypt the NAS safe mode command completion message and forward it to the AMF.

[0057] Step 9: After successful authentication, the AMF can retrieve the UE subscription from the UDM. The AMF can discover the UDM using the SUPI. The AMF can send a UE subscription data request message to the UDM. This message can include the SUPI and the AMF address.

[0058] Step 10: UDM can store AMF address and can return UE subscription data to AMF.

[0059] Step 11: The AMF can include the NAS registration acceptance message in the N2 message. The NAS registration message can be sent to the UE. The NAS registration message can include the registration area, the new GUTI, and mobility restriction information. The N2 message can be sent to the RAN and can also include mobility restriction information.

[0060] Step 12: The RAN can perform security processing on NAS messages and can send NAS registration acceptance messages to the UE through the Uu interface.

[0061] Step 13: The UE can decrypt the NAS message, store the registration area, GUTI and mobility restriction information, and send a registration completion message to the AMF.

[0062] Following this process, the UE successfully registered with the network.

[0063] Example of implementation method 2 Figure 6 A sequence diagram of an example PDU session establishment process according to some embodiments of this disclosure is shown. During this process, the RAN can discover the SMF and can communicate directly with the SMF without the involvement of the AMF.

[0064] Step 1: The UE may send a NAS message (e.g., a PDU session establishment request) to the RAN. The NAS message may include at least one of the following: (one or more) S-NSSAI, DNN, PDU session ID, or request type. The NAS message may also include a SUPI that uniquely identifies the UE.

[0065] Step 2: The RAN can select an SMF for the PDU session via the NRF or through local configuration. In the case of via the NRF, the RAN can provide the NRF with the DNN and S-NSSAI so that the NRF can select an SMF for the RAN. The RAN can then forward a PDU session establishment request to the selected SMF, along with at least one of the following: UE location information, access type, or RAT type. If the UE does not provide a SUPI in the PDU session establishment request message, the RAN can also send a SUPI to the selected SMF.

[0066] Step 3: SMF can retrieve UE subscription data for S-NSSAI and DNN from UDM using SUPI, S-NSSAI, and DNN.

[0067] Step 4: The SMF can determine QoS flow parameters based on subscriptions and (one or more) PCC rules. The SMF can select a UPF to serve the PDU session and can configure detection rules and service processing rules for the UPF for QoS flows. The UPF can allocate N3 tunnel information for uplink services.

[0068] Step 5: The SMF can send a RAN Resource Request message to the RAN to request radio resource allocation for the QoS flow used in the PDU session. This message may include the QoS profile of the QoS flow and / or the N3 tunnel information of the UPF.

[0069] Step 6: The RAN can communicate with the UE to allocate radio resources for QoS flows. The RAN can also allocate RANN3 tunnel information for PDU sessions.

[0070] Step 7: The RAN can send a radio resource response message to the SMF, including RAN N3 tunnel information for the PDU session.

[0071] Step 8: The SMF can provide the UPF with RAN N3 tunnel information for the PDU session.

[0072] Step 9: The SMF can send a PDU session registration request message to the UDM. This message may include the SMF address and / or the PDU session ID. The UDM can store the PDU session ID and the SMF address and can return a response to the SMF.

[0073] Step 10: The SMF can send a PDU session establishment accept message to the RAN. This message may include the UE IP address for the PDU session. Alternatively, the SMF can use a user-assigned UP IP address for the UE.

[0074] Step 11: The RAN can forward the PDU session establishment accept message to the UE.

[0075] Following this process, a PDU session is established, and the PDU session information is stored in the UDM. This process avoids interaction between the AMF and SMF.

[0076] Example of implementation method 3 Figure 7 A sequence diagram of an example switching process according to some embodiments of the present disclosure is shown. Figure 7 This demonstrates how direct communication between the RAN and SMF can be supported during Xn-based handover.

[0077] Step 0: Before the handover, the user plane used to transmit uplink and downlink data can be between the UE and the source RAN, and between the source RAN and the UPF.

[0078] Step 1: Based on radio measurements, the source RAN can initiate an Xn-based handover to the target RAN by sending a handover preparation request message. This message may include at least one of the following: PDU session ID, the SMF address or intermediate SMF (I-SMF) address of the PDU session, the QoS profile information of the PDU session, or the radio resource information of the PDU session.

[0079] Step 2: The target RAN can determine the radio resources reserved for the QoS flow of the PDU session received from the source RAN. The target RAN can return a handover preparation response message to the source RAN. This message can include all radio resource information successfully reserved for the UE in the target RAN.

[0080] Step 3: The source RAN can send a handover command message to the UE. This message may include radio resources received from the target RAN.

[0081] Step 4: Based on the radio resources received from the source RAN, the UE can access the target RAN and establish a radio connection with the target RAN.

[0082] Step 5: Based on the received SMF address (or the old I-SMF address), if the target RAN determines that it cannot connect to the SMF (or the old I-SMF), the target RAN can select a new I-SMF (intermediate SMF) that can communicate directly with the target RAN.

[0083] Step 6: The target RAN can send a PDU session creation request message to the selected I-SMF, including N2 SM information and the SMF address of the PDU session (the old I-SMF address). The N2 SM information may include the target RAN N3 user plane information of the PDU session. The target RAN N3 tunnel can be used between the target RAN and the I-UPF (Intermediate User Plane Function).

[0084] Step 7: The I-SMF can send a PDU session context request message to the SMF (the old I-SMF) to retrieve the session management context.

[0085] Step 8: The SMF (the old I-SMF) can return the session management context, including the UPF N9 tunnel information for the PDU session. The N9 tunnel can be used between the I-UPF and the UPF.

[0086] Step 9: The I-SMF can select the I-UPF and can send an N4 session establishment request message to the I-UPF, including the target RAN N3 user plane information of the PDU session received from the target RAN, and the UPF N9 tunnel information received from the SMF (the old I-SMF).

[0087] Step 10: I-UPF can be allocated and can provide I-SMF with I-UPF N3 user plane information and I-UPF N9 user plane information of PDU session.

[0088] Step 11: The I-SMF can send a PDU session update request message to the SMF, including the I-UPF N9 user plane information of the PDU session received from the I-UPF.

[0089] Step 12: The SMF can send an N4 session modification request message to the UPF to update the I-UPF N9 user plane information.

[0090] Step 13: The UPF can send an N4 session modification response message to the SMF.

[0091] Step 14: The SMF can send a PDU session update response message to the I-SMF.

[0092] Step 15: The I-SMF can return a PDU session creation response message to the target RAN.

[0093] Step 16: After the handover, the UE can perform the UE registration process via the target RAN.

[0094] Following this process, the user plane of the PDU session is now located between the UE and the target RAN, between the target RAN and the I-UPF (N3 tunnel), and between the I-UPF and the UPF (N9 tunnel). During this process, there is no interaction between the AMF and SMF, thus simplifying the handover process.

[0095] It should be understood that one or more features from the above implementation examples are not unique to that specific implementation example, but can be combined in any way (e.g., with any priority and / or order, concurrently or otherwise).

[0096] Figure 8 A flowchart of method 800 for switching is shown. Method 800 can be used in conjunction with this document. Figures 1 to 7 It may be implemented by any one or more of the components and devices described in detail. Generally, in some embodiments, method 800 may be performed by a wireless communication node (e.g., a target RAN). Depending on the embodiment, additional, fewer, or different operations may be performed in method 800. At least one aspect of the operations relates to a system, method, apparatus, or computer-readable medium.

[0097] A first wireless communication node (e.g., a target radio access network (RAN)) may select a first network entity (e.g., a Session Management Function (SMF) or an I-SMF) for direct communication with the first wireless communication node. The first wireless communication node may send a Packet Data Unit (PDU) session creation request message to the selected first network entity. The PDU session creation request message may include session management (SM) information and the session management function (SMF) address of the PDU session. The SM information may include N2 SM information. The N2 SM information may include N3 user plane information of the PDU session.

[0098] In some embodiments, the first wireless communication node may receive a handover preparation request message from a second wireless communication node (e.g., the source RAN). The handover preparation request message may include at least one of the following: PDU session identifier (ID); SMF address of the PDU session; Quality of Service (QoS) profile information of the PDU session; or radio resource information of the PDU session.

[0099] In some embodiments, the first wireless communication node may determine at least one radio resource reserved for the Quality of Service (QoS) flow of the PDU session. The first wireless communication node may send a handover preparation response message to the second wireless communication node, wherein the handover preparation response message includes information about the determined at least one radio resource.

[0100] In some embodiments, the first wireless communication node may receive a PDU session creation response corresponding to a session creation request message from a selected first network entity.

[0101] In some embodiments, the wireless communication device may perform a user equipment (UE) registration process via a first wireless communication node. The first wireless communication node may receive a PDU session establishment request message from the wireless communication device (e.g., the UE). The PDU session establishment request message may include at least one of the following: Single Network Slice Selection Assistance Information (S-NSSAI); Data Network Name (DNN); PDU Session Identifier (ID); or Request Type. Selecting a first network entity for direct communication with the first wireless communication node includes: the first wireless communication node determining the first network entity based on the PDU session establishment request message. The first wireless communication node transmits the PDU session establishment request message to the selected first network entity.

[0102] In some embodiments, the first wireless communication node may receive a resource request message from a selected first network entity, the resource request message being used to request the allocation of radio resources for at least one Quality of Service (QoS) stream corresponding to a PDU session establishment request message. The resource request message includes at least one QoS profile and N3 tunnel information for the User Plane Function (UPF).

[0103] In some embodiments, a first wireless communication node may receive a security mode command message from a second network entity (e.g., an Access and Mobility Management Function (AMF)). The security mode command message may include at least one security context for protecting communication between a wireless communication device (e.g., a UE) and the first wireless communication node. The first wireless communication node may transmit a registration request message to the second network entity (e.g., the Access and Mobility Management Function (AMF)). The registration request message may include at least one of the following: registration type; globally unique temporary identifier (GUTI); at least one security parameter; or user equipment (UE) mobility management (MM) core network capabilities. The second network entity may perform a UE authentication process based on the registration request message.

[0104] While various embodiments of the solution have been described above, it should be understood that these embodiments are presented by way of example only and not by way of limitation. Similarly, various schematic diagrams may depict exemplary architectures or configurations, which are provided to enable those skilled in the art to understand exemplary features and functions of the solution. However, those skilled in the art will understand that the solution is not limited to the exemplary architectures or configurations shown, but can be implemented using various alternative architectures and configurations. Furthermore, as those skilled in the art will understand, one or more features of one embodiment herein may be combined with one or more features of another embodiment described herein. Therefore, the breadth and scope of this disclosure should not be limited to any of the exemplary embodiments described above.

[0105] It should also be understood that any references to elements in this document using names such as "first," "second," etc., generally do not restrict the number or order of these elements. Rather, these names may be used in this document as a convenient means of distinguishing two or more elements, or multiple instances of a single element. Therefore, a reference to the first element and the second element does not imply that only two elements can be used, or that the first element must somehow precede the second element.

[0106] Furthermore, those skilled in the art will understand that various techniques and skills can be used to represent information and signals. For example, data, instructions, commands, information, signals, bits, and symbols that may be mentioned in the above description can be represented by voltage, current, electromagnetic waves, magnetic fields or particles, light fields or particles, or any combination thereof.

[0107] Those skilled in the art will further understand that any of the various illustrative logic blocks, modules, processors, means, circuits, methods, and functions described in connection with the aspects disclosed herein can be implemented by electronic hardware (e.g., digital implementation, analog implementation, or a combination of both), firmware, various forms of program or design code in conjunction with instructions (which may be referred to herein as "software" or "software module" for convenience), or any combination of these technologies. To clearly illustrate the interchangeability of hardware, firmware, and software, the various exemplary components, blocks, modules, circuits, and steps described above are generally described in terms of their functionality. Whether such functionality is implemented as hardware, firmware, or software, or a combination of these technologies, depends on the specific application and the design constraints imposed on the system as a whole. Those skilled in the art can implement the described functionality in various ways for each specific application, but such implementation will not depart from the scope of this disclosure.

[0108] Furthermore, those skilled in the art will understand that the various exemplary logic blocks, modules, devices, components, and circuits described herein can be implemented within or executed by an integrated circuit (IC), which may include a general-purpose processor, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), or other programmable logic devices, or any combination thereof. Logic blocks, modules, and circuits may also include antennas and / or transceivers for communicating with various components within a network or device. A general-purpose processor may be a microprocessor, but alternatively, the processor may be any conventional processor, controller, or state machine. The processor may also be implemented as a combination of computing devices, such as a combination of a DSP and a microprocessor, a combination of multiple microprocessors, a combination of one or more microprocessors combined with a DSP core, or any other suitable configuration that performs the functions described herein.

[0109] If these functions are implemented in software, they can be stored as one or more instructions or code on a computer-readable medium. Therefore, the steps of the methods or algorithms disclosed herein can be implemented as software stored on a computer-readable medium. Computer-readable media include both computer storage media and communication media, with the latter including any medium capable of transferring a computer program or code from one location to another. Storage media can be any available medium accessible to a computer. By way of example and not limitation, such computer-readable media can include RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium that can be used to store the required program code in the form of instructions or data structures and that is accessible to a computer.

[0110] In this document, the term "module" as used herein refers to software, firmware, hardware, and any combination of such elements for performing the relevant functions described herein. Furthermore, for purposes of discussion, individual modules are described as discrete modules; however, as will be apparent to those skilled in the art, two or more modules can be combined to form a single module that performs the relevant functions according to embodiments of the present solution.

[0111] Furthermore, memory or other storage devices, as well as communication components, may be used in embodiments of this solution. It should be understood that, for clarity, the above description refers to embodiments of this solution described with reference to different functional units and processors. However, it will be apparent that any suitable functional distribution among different functional units, processing logic elements, or domains can be used without impairing this solution. For example, functions shown to be performed by separate processing logic elements or controllers may be performed by the same processing logic element or controller. Therefore, references to specific functional units are merely references to suitable means for providing the described functions and do not indicate a strict logical or physical structure or organization.

[0112] Various modifications to the embodiments described in this disclosure will be apparent to those skilled in the art, and the general principles defined herein can be applied to other embodiments without departing from the scope of this disclosure. Therefore, this disclosure is not intended to be limited to the embodiments shown herein, but is given the broadest scope consistent with the novel features and principles disclosed herein as set forth in the following claims.

Claims

1. A method comprising: selecting, by a first wireless communication node, a first network entity for direct communication with the first wireless communication node; and sending, by the first wireless communication node, a packet data unit (PDU) session creation request message to the selected first network entity, wherein the PDU session creation request message comprises session management (SM) information of a PDU session and a session management function (SMF) address. The SM information comprises N2 SM information.

2. The method of claim 1, wherein, The N2 SM information comprises N3 user plane information of the PDU session.

3. The method of claim 2, wherein, 4. The method of claim 1, comprising: receiving, by the first wireless communication node, a handover preparation request message from a second wireless communication node. The handover preparation request message comprises at least one of:

5. The method of claim 4, wherein, a PDU session identification (ID); or an SMF address of the PDU session; or quality of service (QoS) profile information of the PDU session; or radio resource information of the PDU session.

6. The method of claim 4, comprising: determining, by the first wireless communication node, at least one radio resource for quality of service (QoS) flow reservation of the PDU session; and sending, by the first wireless communication node, a handover preparation response message to the second wireless communication node, wherein the handover preparation response message comprises information of the determined at least one radio resource.

7. The method of claim 1, comprising: receiving, by the first wireless communication node, a PDU session creation response corresponding to the session creation request message from the selected first network entity. performing, by a wireless communication device, a user equipment (UE) registration procedure via the first wireless communication node.

9. The method of claim 1, comprising:

8. The method of claim 1, wherein, receiving, by the first wireless communication node, a PDU session establishment request message from a wireless communication device. The PDU session establishment request message comprises at least one of: a subscription permanent identifier (SUPI); or 10. The method of claim 9, wherein, a data network name (DNN); or a PDU session identification (ID); or Single Network Slice Selection Assistance Information (S NSSAI); or a request type. Selecting the first network entity for direct communication with the first wireless communication node comprises: determining, by the first wireless communication node, the first network entity according to the PDU session establishment request message.

11. The method of claim 9, wherein, 12. The method of claim 11, comprising: transmitting, by the first wireless communication node, the PDU session establishment request message to the selected first network entity.

13. The method of claim 12, comprising: receiving, by the first wireless communication node, a resource request message from the selected first network entity, the resource request message being used to request radio resource allocation for at least one quality of service (QoS) flow corresponding to the PDU session establishment request message, wherein the resource request message comprises at least one quality of service (QoS) profile and N3 tunnel information of a user plane function (UPF).

14. The method of claim 1, comprising: ​ ​ receiving, by the first wireless communication node, a security mode command message from a second network entity, wherein the security mode command message comprises at least one security context for protecting communications between a wireless communication device and the first wireless communication node.

15. The method of claim 1, comprising: transmitting, by the first wireless communication node, a registration request message to a second network entity, wherein the registration request message comprises at least one of: a subscription permanent identifier (SUPI); or a registration type; or a globally unique temporary identifier (GUTI); or at least one security parameter; or a user equipment (UE) mobility management (MM) core network capability.

16. The method of claim 15, wherein, performing, by the second network entity, a UE authentication procedure based on the registration request message.

17. A non-transitory computer-readable medium storing instructions that, when executed by at least one processor, cause the at least one processor to perform the method of any of claims 1-16.

18. An apparatus comprising: at least one processor configured to implement a method according to any of claims 1-16.

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