5g核心网和关键技术和功能介绍-nokia

5G核心网关键技术和功能介绍目录1.5G核心网架构和各主要NF功能描述2.5G核心网关键技术介绍-基于服务的构架SBA-控制面和用户面分离CUPS-计算与存储分离-网络切片构架和选择NSSF3.注册管理和连接管理RM/C M-用户标识-不同的注册管理流程和功能-几种不同的连接管理状态分析4.会话管理SM-PDU会话的一些特性介绍-会话和业务连续性模式介绍-基于流的QoS模型介绍-边缘计算和本地路由功能5.5G的关键呼叫流程-注册流程-PDU会话建立流程-切换流程1.5G核心网架构和各主要NF功能描述5G Service Based Architecture (SBA)AUSF UE(R)AN UPF N2N3N1N9AMF N4AF PDNN6N4PCF SMF UDM USER PLANE CONTROL PLANE Local PDN UPF N1N2UE AP N3IWF N3NEF 3rd party appl.DSF NRF Service based interfaces (APIs) “on demand”Authenti-ficationAccess &Mobility MgmtUnified data mgmt 5G Core (SBA)Service Based ArchitectureApplication Function Session Mgmt Data Storage Function User Plane FunctionPolicy Ctrl Function Network repository Function Network Exposure function AMF: Access and Mobility management FunctionSMF: Session Management FunctionUPF: User Plane FunctionUDSF: Unstructured Data Storage Function AUSF: Authentication Server Function UDM: Unified Data Management UDR: Unified Data Repository N3IWF: Non-3GPP Interworking Function NRF: Network Repository Function NEF: Network Exposure Function NSSF: Network Slice Selection Function PCF: Policy Control FunctionAccess and Mobility Management function (AMF)•Mandatory functionality•Termination of RAN control interface (N2)•Termination of NAS (N1), NAS ciphering and integrity protection•Access authentication and authorization•Security anchor function and security context mgmt for access security key handling•Registration, connection, reachability, and mobility management•Session mgmt message transport and proxy between UE and Session Management Function (SMF)•SMS transport between UE and SMSF•Lawful interception•Optional functionality•Support of mandatory functionality for non-3GPP access•N3IWF N2 interface termination and NAS signaling5G System ArchitectureAMF SMF PCFEIRAUSFUEN1N2N3InternetUPF4G/5GN4IMSN3IWFNSSFN5SMSFNRF UDSF UDR NEF AFUDMn3GPPAll network functions can interact with NRF,UDSF, UDM, UDR, and NEF as necessaryBGWHSSTASIMSN6MRFLMFSession Management function (SMF)•Session establishment, modify and release inc N3 tunnel •UE IP address allocation & management•Selection and control of UP function (UPF)•UPF traffic steering configuration to proper destination •Termination of interfaces towards Policy control functions •Control part of policy enforcement and QoS•Charging data collection and support of charging interfaces •Control and coordination of charging data collection at UPF •Termination of SM parts of NAS messages•Downlink Data Notification•Initiator of AN specific SM information via AMF over N2•Determine SSC mode of a session•Lawful intercept•Roaming functionality (local QoS, charging, LI)5G System ArchitectureAMF SMF PCFEIRAUSFUEN1N2N3InternetUPF4G/5GN4IMSN3IWFNSSFN5SMSFNRF UDSF UDR NEF AFUDMn3GPPAll network functions can interact with NRF,UDSF, UDM, UDR, and NEF as necessaryBGWHSSTASIMSN6MRFLMFUser plane function (UPF)•Anchor point for Intra-/Inter-RAT mobility (when applicable)•External PDU session point of interconnect to Data Network •Packet routing & forwarding•Packet inspection and User plane part of Policy rule enforcement•Lawful intercept (UP collection)•Traffic usage reporting.•Uplink classifier to support routing traffic flows to a data network.•Branching point to support multi-homed PDU session.•QoS handling for user plane, e.g. packet filtering, gating, UL/DL rate enforcement•Uplink Traffic verification (SDF to QoS flow mapping).•Transport level packet marking in the uplink and downlink.•Downlink packet buffering and downlink data notification triggering.5G System ArchitectureAMF SMF PCFEIRAUSFUEN1N2N3InternetUPF4G/5GN4IMSN3IWFNSSFN5SMSFNRF UDSF UDR NEF AFUDMn3GPPAll network functions can interact with NRF,UDSF, UDM, UDR, and NEF as necessaryBGWHSSTASIMSN6MRFLMFNetwork Repository Function (NRF)•Supports service discovery function•Receive NF Discovery Request from NF instance, and provides the information of the discovered NF instances (be discovered) to the NF instance•Maintains the NF profile of available NF instances and their supported services (e.g. ID, Type, PLMN, Slice, FQDN,capabilities, authorization information, service names)•All network functions interact with NRF•Multiple NRFs can be deployed in network slicing per PLMN, per group of slices, or slice specific•In roaming cases VPLMN and HPLMN may be used5G System ArchitectureAMF SMF PCFEIRAUSFUEN1N2N3InternetUPF4G/5GN4IMSN3IWFNSSFN5SMSFNRF UDSF UDR NEF AFUDMn3GPPAll network functions can interact with NRF,UDSF, UDM, UDR, and NEF as necessaryBGWHSSTASIMSN6MRFLMFUnstructured Data Storage Function (UDSF)•Storage and retrieval of information as unstructured data by any NF (e.g. context, state, session)•All network functions can interact with UDSF (via N18/Nudsf interface)•NFs may share a UDSF for storing their respective unstructured data or may each have their own UDSF •Deployments can choose to collocate UDSF with UDRUnstructured Data Storage Function (UDSF)Context State SessionAny NFN18/Nudsf5G System ArchitectureAMF SMF PCFEIRAUSFUEN1N2N3InternetUPF4G/5GN4IMSN3IWFNSSFN5SMSFNRF UDSF UDR NEF AFUDMn3GPPAll network functions can interact with NRF,UDSF, UDM, UDR, and NEF as necessaryBGWHSSTASIMSN6MRFLMFUnified Data Repository (UDR)•Storage and retrieval of subscription data by the UDM FE •Storage and retrieval of policy data by the PCF.•Storage and retrieval of structured data for exposure, and application data (including Packet Flow Descriptions (PFDs) for application detection, application request information for multiple UEs), by the NEF•Deployments can choose to collocate UDSF with UDRUnified Data Repository (UDR)Subscription Policy Exposure ApplicationUDM FE PCF FE NEF FENudr5G System ArchitectureAMF SMF PCFEIRAUSFUEN1N2N3InternetUPF4G/5GN4IMSN3IWFNSSFN5SMSFNRF UDSF UDR NEF AFUDMn3GPPAll network functions can interact with NRF,UDSF, UDM, UDR, and NEF as necessaryBGWHSSTASIMSN6MRFLMFUnified Data Management (UDM)•3GPP AKA Authentication Credential Processing•User Identification Handling•Access Authorization•Registration/Mobility management•Subscription management•SMS management•UDM uses subscription data and authentication data that may be stored in UDR5G System ArchitectureAMFUPFSMFPCFEIRAUSFUEN1N2N3InternetUPF4G/5GN4N9IMSN4N3IWFNSSFN5N7N11N22N12SMSFN20NRF UDSF UDR NEF AFN17N15UDMN8n3GPPAll network functions can interact with NRF,UDSF, UDM, UDR, and NEF as necessaryBGWHSSTASIMSN6MRFNetwork Exposure Function (NEF)•Securely expose the services and capabilities provided by3GPP network functions for e.g 3rd party, internalexposure/re-exposure, Application Functions, EdgeComputing•Provides a means for the Application Functions to securely provide information to 3GPP network, e.g. Mobility Pattern, communication pattern•Authenticate, authorize and throttle the Application Functions•Translation information between AF and internal network function•Receives information from other network functions (based on exposed capabilities of other network functions)•May implement a Front End (NEF FE) to store the received information as structured data using a standardizedinterface to a Unified Data Repository (UDR). The storedinformation can be accessed and "re-exposed" by the NEF to other network functions and Application Functions, and used for other purposes such as analytics.5G System ArchitectureAMF SMF PCFEIRAUSFUEN1N2N3InternetUPF4G/5GN4IMSN3IWFNSSFN5SMSFNRF UDSF UDR NEF AFUDMn3GPPAll network functions can interact with NRF,UDSF, UDM, UDR, and NEF as necessaryBGWHSSTASIMSN6MRFLMFNetwork Slice Selection Function (NSSF)•Selecting the set of network slice instances serving the UE •Determining the Allowed NSSAI•Determining the AMF Set to be used to serve the UE, or, based on configuration, a list of candidate AMF(s), possibly by querying the NRF.5G System ArchitectureAMF SMF PCFEIRAUSFUEN1N2N3InternetUPF4G/5GN4IMSN3IWFNSSFN5SMSFNRF UDSF UDR NEF AFUDMn3GPPAll network functions can interact with NRF,UDSF, UDM, UDR, and NEF as necessaryBGWHSSTASIMSN6MRFLMFAuthentication Server Function (AUSF)•Supports Authentication Server Function (AUSF) as specified by SA WG35G System ArchitectureAMF SMF PCFEIRAUSFUEN1N2N3InternetUPF4G/5GN4IMSN3IWFNSSFN5SMSFNRF UDSF UDR NEF AFUDMn3GPPAll network functions can interact with NRF,UDSF, UDM, UDR, and NEF as necessaryBGWHSSTASIMSN6MRFLMFPolicy Control Function (PCF)•Supports unified policy framework to govern network behavior•Provides policy rules to Control Plane function(s) to enforce them•Implements a Front End (PCF FE) to access subscription information relevant for policy decisions in a Unified Data Repository (UDR)5G System ArchitectureAMF SMF PCFEIRAUSFUEN1N2N3InternetUPF4G/5GN4IMSN3IWFNSSFN5SMSFNRF UDSF UDR NEF AFUDMn3GPPAll network functions can interact with NRF,UDSF, UDM, UDR, and NEF as necessaryBGWHSSTASIMSN6MRFLMFNon-3GPP InterWorking Function (N3IWF)•UE IPSEC/IKE tunnel termination•Termination of N2 and N3 interfaces to 5G Core Network for Control-Plane and user-plane respectively•Relaying uplink and downlink control-plane NAS (N1) signaling between the UE and AMF•Handling of N2 signaling from SMF (relayed by AMF) related to PDU sessions and QoS•Establishment of IPsec Security Association (IPsec SA) to support PDU Session traffic•Relaying uplink and downlink user-plane packets between the UE and UPF. (De-capsulation/Encapsulation of packets for IPSec and N3 tunneling)•Enforcing QoS corresponding to N3 packet marking, taking into account QoS requirements associated to such marking received over N2•N3 user-plane packet marking in the uplink.•Local mobility anchor within untrusted non-3GPP access networks using MOBIKE•Supporting AMF selection5G System ArchitectureAMF SMF PCFEIRAUSFUEN1N2N3InternetUPF4G/5GN4IMSN3IWFNSSFN5SMSFNRF UDSF UDR NEF AFUDMn3GPPAll network functions can interact with NRF,UDSF, UDM, UDR, and NEF as necessaryBGWHSSTASIMSN6MRFLMF2.5G核心网关键技术介绍基于服务的构架SBATechnology behind: Modularity and SBANetwork Function Service Framework•Control Plane•An NF service is one type of capability•NF Service Producer•Authorized NF Service Consumer•Network Function may expose one or more NF services •through a service-based interface, two mechanisms -"Request-response“-"Subscribe-Notify"SBA requires service framework and identification of services Framework ConceptDiscovery•NF discovery, NF service discovery enables a CP NF to discover a NF instance(s) that provides the expected NF service(s). It is implemented either via configuration or optionally by using the NRF •The requester NF performs the selection if the NRF returns more than one options•The requester NF might cache the results of the discovery request for subsequent useMultiple NRFs can be deployed at different levels:•PLMN level (the NRF is configured with information for the whole PLMN)•shared-slice level (the NRF is configured with information relevant for the common NFs of a set of Network Slices)•slice-specific level (the NRF is configured with information belonging to an S-NSSAI) Authorization Entails Two steps:Check whether the requester NF is permitted to discover the requested NF instance during the NFservice discovery procedure NF level granularityCheck whether the requester NF is permitted to access the requested NF for consuming the NFservice. This is either per NF or per UE/roaming agreement granularity. NF Service authorization perUE granularity is embedded in the related NF service logicRegistration and De-registration Registration / De-registration of NF profile and NF services with Network repository function via direct interaction between NF –NRF or OAMSBA protocol solution•Uniform solution for all 5G Service-Based Interfaces•SBA protocol: HTTP/2•Transport: TCP•Serialization protocol: JSON•The OpenAPI3.0.0 is adopted as the Interface Definition Language•API design style: RESTful APIs whenever possible, complemented by custom methods for service operations that cannot be designed as CRUD operations控制面和用户面分离CUPSTechnology behind: CP UP Separation•Centralized CP and BUSstructure•Distributed UP•UPF selection and re-selection•Close to UE (Edge)•ULCL•Branching-pointselective traffic routingUplink Classifier(UL-CL)•IPv4, IPv6 & Ethernet PDU’s•Transparent to UE-exist more than one UPF-but one UL CL is connected to RAN•Classification rules provided in run time by SMF•Classifies based on target characteristics of the flowsUsage of IPv6 multi-homing PDU Session •multi PDU Session Anchorwithmultiple IPv6 prefixes.•branch out at a "Branching Point"UPF-forwarding UL traffic towards differentPDU Session Anchors and merge DLtraffic to UE•The use of multiple IPv6 prefixes :- a Branching Point spread UL trafficbased on Source Prefix-to support make-before-break servicecontinuity –SSC mode 3-to support UE access both local serviceand central service计算与存储分离5G Data Storage architectures•Allows any control plane NF to store and retrieve its unstructured data (session state) into/from a UDSF (Unstructured Data Storage Network Function)•UDSF belongs to the same PLMN where the NF is located •CP NFs may share a UDSF or may each have its own UDSF •5G phase 1 specifies AMF procedures if UE context is stored in UDSF •N18/Nudsf: Protocol will not be specified in Rel. 15Unstructured Data StorageFunction (UDSF)Unified Data Repository (UDR)•Allows the UDM, PCF, NEF to store data in the UDR (Unified Data Repository)•UDR can be deployed in each PLMN. There can be multiple UDRs deployed in a network each accommodating different data sets/subsets. Deployments where a UDR serves a single NF and stores its data and thus can be integrated with this NF, can be possible, e.g. a UDM with build-in UDR•Data exposed via Nudr (subscription, policy, structured data for exposure,application request information for multiple UEs) shall be standardized. In addition it shall be possible to access operator specific data sets/data not standardized. The organization of the data stored in UDR shall not be standardized •Nudr: service based interface http2 based. Nudr is always intra-PLMN, Nudm is inter-PLMN in roamingN18/NudsfAny NFUDSFSubscription DataPolicy DataStructured Data for exposureApplication DataUDRUDM FEPCF FENEF FENudrTechnology behind: Compute –Storage Separation•stateless NFV网络切片构架和选择NSSFNetwork Slice Identification S-NSSAI identifies a Network Slice, comprised of:• A Slice/Service type (SST), refers to theexpected Network Slice behaviour in terms offeatures and services;• A Slice Differentiator (SD), optional todifferentiate multiple Network Slices of thesame Slice/Service type.•can have standard values or non-standard values•The NSSAI is a collection of S-NSSAIs.• a Network Slice instance can be associated with one or more S-NSSAIs, and an S-NSSAIcan be associated with one or more NetworkSlice instances.Slice Examples in 5GC & 5G RANeMBBUPF SMFUPFSMF eMBBCONTROL PLANE AMF UPFSMF eMTCSHARED DEDICATEDSLICE #1SLICE #2SLICE #3AMFRRC/P DCPN2MAC PHYSDAPPDCPSDAPPDCPRRC/P DCPN2SDAPUE 1UE 25G (R)ANN1 ( SST#1, SD#A)N1 ( SST#1, SD#B; SST#2, SD#B)N2N2N3N3N3SHAREDDEDICATEDPDCPSST#1SD#BS-NSSAI#1S-NSSAI#2UE 1 NSSAISST#2SD#B SST#1S-NSSAI#1UE 2 NSSAISD#ASST#1: eMBB Service Slice SST#2: eMTC Service Slice SD#A:Enterprise A SD#B:Enterprise BEnterprise AEnterprise BEnterprise BRRC ( SST#1, SD#A)RRC ( SST#1, SD#B; SST#2, SD#B)RAN Slice SelectionFunction5G Network Architecture for Network SlicingSlice Specific Network FunctionsN3DNN2N7/N10/N11N1N5UPFNG-AFN4NG-SMFN6(*) Could be left up to operator decisionNEFNRFSlice Common Network FunctionsUDM AMF AUSFPCF(*)(*)(*)NSSFUENG-RAN Shared resources Dedicated resources•Slicing privacy not included in Rel. 15Different Network Slice Deployment scheme •Independent CP and UP•Partially-shared CP•Fully-shared CPNetwork Slices Selection•comprises two steps:-performing a RM procedure to select an AMF that supports the required Network Slices.-establishing one or more PDU Session to the required Data network via the Network Slice Instance(s).UE Registration1.Configured NSSAI provisioned to UE and NS Selection Policy (NSSP): Rules associating an App with an S-NSSAI and DNN linked to the App2.UE sends Reg. Req. including Requested NSSAI. RAN selects AMF based on Requested NSSAI (assumption 5G-GUTI is not provided)3.AMF fetches subscription data from UDM. UDM returns (Sub data+ Subscribed NSSAI)4.AMF interrogates NSSF for Slice Selection if it cannot serve the UE: NSSF returns set of NSI ID, Allowed S-NSSAI, target AMF set. A target AMF isselected by the AMF initially received the request and rerouting to the target AMF applies5.AMF sends Registration Accept/Complete (Allowed S-NSSAIs, 5G-GUTI, Registration area. Mobility restrictions, …) to both RAN and UE (NAS)6.Subsequently UE uses updated NSSAI providing list of Allowed S-NSSAIs3.注册管理和连接管理RM/CM用户标识•5G Subscription Permanent Identifier (SUPI)-For interworking with EPC, SUPI shall be IMSI based-SUCI: the concealed SUPI.•Permanent Equipment Identifier (PEI)-PEI can be different formats for different UE types and use cases.-in this release, the only format is IMEI•temporary identifier (5G-GUTI)-AMF allocates-common to both 3GPP and non-3GPP access-<5G-GUTI> := <GUAMI> <5G-TMSI>-<GUAMI> := <MCC> <MNC> <AMF Region ID> <AMF Set ID> <AMF Pointer>-<5G-S-TMSI> := <AMF Set ID> <AMF Pointer> <5G-TMSI>-Load balancing by 5G-AN node is only performed between AMFs of same AMF set•Generic Public Subscription Identifier (GPSI)-for addressing a 3GPP subscription in different data networks outside of the 3GPP system.-GPSIs are public identifiers used both inside and outside of the 3GPP system-either an MSISDN or an External Identifier•SUCI-SUPI should not be transferred in clear text over 5G RAN except routing information,e.g. Mobile Country Code (MCC) and Mobile Network Code (MNC).-home network public key shall be stored in the USIM.Registration Area•per access type i.e., 3GPP access or Non-3GPP access•over 3GPP access, AMF allocates a set of tracking areas in TAI List to UE.-take into account (e.g. Mobility Pattern and Allowed/Non-Allowed Area )-may allocate the whole PLMN ("all PLMN") as registration area to a UE in MICO modeData Network Name (DNN)•equivalent to an APN•DNN may be used e.g. to:-Select a SMF and UPF(s) for a PDU Session.-Select N6 interface(s) for a PDU Session.-Determine policies to apply to this PDU Session.PDU Session•It provide a PDU Connectivity Service between a UE and a data network identified by a DNN.•PDU Sessions ID assigned by UE.•The defined PDU Session types : IPv4, IPv6, IPv4v6, Ethernet,Unstructured.不同的注册管理流程和功能Registration Management•to register/deregister a UE/user with network-establish user context in network.•Initial Registration procedure:•Periodic Registration Update•Mobility Registration Update-to update its capabilities or re-negotiate protocol parameters5GS Registration Management State modelsRM contexts in AMF•UDM manages separate UE Registration procedures for each access •For a serving PLMN, multiple access-specific RM contexts for an UE: - a 5G-GUTI (common to 3GPP/Non-3GPP accesses)- a Registration state per access type- a Registration Area per access type-timers for 3GPP access•Periodic Registration timer; and• a Mobile Reachable timer and an Implicit Deregistration timer.-timers for non-3GPP access•5G-GUTI enables the AN to select an AMF几种不同的连接管理状态分析。