Patent ID: 12207219

DETAILED DESCRIPTION

Reference will now be made in detail to some embodiments of the invention, examples of which are illustrated in the accompanying drawings.

FIG.1schematically shows a communication system100having a Public Land Mobile Network (PLMN)110and a Stand-alone Non-public Network (SNPN)120supporting enhanced network identifier (NID) provisioning under UE mobility in accordance with one novel aspect. PLMN network110comprises control plane functionalities, user plane functionality (UPF), and application servers that provides various services by communicating with a plurality of user equipments (UEs) including UE111. UE111and its serving base station gNB112belong to part of a radio access network RAN130. RAN130provides radio access for UE111via a radio access technology (RAT), e.g. 3GPP access and non-3GPP access. An access and mobility management function (AMF) in PLMN110communicates with gNB112, and other network functions such as Session Management Function (SMF), Authentication Server Function (AUSF), etc. in PLMN110(not shown).

Similarly, SNPN network120comprises control plane functionalities, user plane functionality (UPF), and application servers that provides various services by communicating with a plurality of user equipments (UEs) including UE121. The combination of a PLMN ID and a Network identifier (NID) identifies an SNPN. UE121and its serving base station gNB122belong to part of a radio access network RAN140. RAN140provides radio access for UE121via a radio access technology (RAT), e.g. 3GPP access and non-3GPP access. An AMF in SNPN120communicates with gNB122, and other network functions such as SMF, AUSF etc. in SNPN120(not shown). UE111/UE121may be equipped with a radio frequency (RF) transceiver or multiple RF transceivers for different application services via different RATs.

When a UE is moving within a PLMN or between the PLMNs, the UE triggers the mobility registration update procedure and provides a 5G Global Unique Temporary Identifier (5G-GUTI) to the target AMF of the target PLMN, to assist the target AMF to find the correct source AMF for retrieving the UE context for the subsequent procedures. However, a UE may move between different type of networks. For example, the UE may move within a PLMN, within a SNPN, between a PLMN and a SNPN, between two different PLMNs, between two different SNPNs, or between a PLMN and a SNPN. If the provided 5G-GUTI is assigned by an SNPN, it may not be a globally unique number. As a result, the target AMF of the target network may not be able to find the correct source AMF, since the derived information from the provided non-unique 5G-GUTI may lead to find incorrect source AMF. Therefore, the mobility registration update procedure may proceed to an un-anticipated exception condition or fail. The UE then needs to initiate an initial registration procedure with the target AMF.

In accordance with one novel aspect, a method of enhanced NID provisioning method is proposed to handle different UE mobility scenarios. When a UE registers to an SNPN, the UE is assigned with a 5G-GUTI by the SNPN. The SNPN is identified by an SNPN ID==PLMN ID+NID. When the UE moves from the SNPN to another target network having a target AMF, the UE triggers a mobility registration update procedure and provides the 5G-GUTI to the target AMF. For example, UE121moves from SNPN120to PLMN110. Since the UE is aware of the SNPN ID when the UE registers to the SNPN, the UE knows that the 5G-GUTI assigned by the SNPN may not be globally unique. Therefore, the existing mobility registration update procedure is enhanced to allow the UE to provide the 5G-GUTI with NID information if the UE knows the 5G-GUTI is assigned by an SNPN. After receiving the 5G-GUTI and NID information provided by the UE, the target AMF can decides whether to initiate the Identity request/respond procedure based on the NID assignment mode. If NID is self-assigned value, the value of PLMN ID (of the 5G-GUTI)+NID may not be (globally) unique. Therefore, the target AMF may need to request the UE to provide UE SUCI/SUPI for the subsequent procedures. If NID is coordinated assigned value, the value of PLMN ID (of the 5G-GUTI)+NID is (globally) unique. Therefore, the target AMF can use the information along with 5G-GUTI to find the correct source AMF. In the example ofFIG.1, when UE121moves from SNPN120to PLMN112, UE121triggers a mobility registration update procedure and provides its 5G-GUTI with NID information to the target AMF in PLMN110, since UE121knows the 5G-GUTI is assigned by SNPN120and may not be unique. The NID information can assist the target AMF to find the source AMF in SNPN120efficiently, preventing potential failure of the mobility registration update procedure.

FIG.2illustrates simplified block diagrams of wireless devices, e.g., a UE201and network entity211in accordance with embodiments of the current invention. Network entity211may be a base station combined with an MME or AMF. Network entity211has an antenna215, which transmits and receives radio signals. A radio frequency RF transceiver module214, coupled with the antenna, receives RF signals from antenna215, converts them to baseband signals and sends them to processor213. RF transceiver214also converts received baseband signals from processor213, converts them to RF signals, and sends out to antenna215. Processor213processes the received baseband signals and invokes different functional modules to perform features in base station211. Memory212stores program instructions and data220to control the operations of base station211. In the example ofFIG.2, network entity211also includes a set of control functional modules and circuit290. Registration circuit231handles registration and mobility procedure. Session management circuit232handles session management functionalities. Configuration and control circuit233provides different parameters to configure and control UE.

Similarly, UE201has memory202, a processor203, and radio frequency (RF) transceiver module204. RF transceiver204is coupled with antenna205, receives RF signals from antenna205, converts them to baseband signals, and sends them to processor203. RF transceiver204also converts received baseband signals from processor203, converts them to RF signals, and sends out to antenna205. Processor203processes the received baseband signals and invokes different functional modules and circuits to perform features in UE201. Memory202stores data and program instructions210to be executed by the processor to control the operations of UE201. Suitable processors include, by way of example, a special purpose processor, a digital signal processor (DSP), a plurality of micro-processors, one or more micro-processor associated with a DSP core, a controller, a microcontroller, application specific integrated circuits (ASICs), file programmable gate array (FPGA) circuits, and other type of integrated circuits (ICs), and/or state machines. A processor in associated with software may be used to implement and configure features of UE201.

UE201also comprises a set of functional modules and control circuits to carry out functional tasks of UE201. Protocol stacks260comprise Non-Access-Stratum (NAS) layer to communicate with an MME or an AMF entity connecting to the core network, Radio Resource Control (RRC) layer for high layer configuration and control, Packet Data Convergence Protocol/Radio Link Control (PDCP/RLC) layer, Media Access Control (MAC) layer, and Physical (PHY) layer. System modules and circuits270may be implemented and configured by software, firmware, hardware, and/or combination thereof. The function modules and circuits, when executed by the processors via program instructions contained in the memory, interwork with each other to allow UE201to perform embodiments and functional tasks and features in the network. In one example, system modules and circuits270comprise registration circuit221that performs registration procedure with the network, a mobility handling circuit222that handles mobility management, a config and control circuit223that handles configuration and control parameters.

FIG.3Ashows the content of a 5G Global Unique Temporary Identifier (5G-GUTI), and examples when assigned by PLMN and by SNPN. A temporary user identity for 5GS-based services, the 5G-GUTI, is used for identification within the signalling procedures. Upon receiving a Registration Request message of type “initial registration” or “mobility registration update” from a UE, the AMF sends a new 5G-GUTI to the UE in Registration Accept message. Upon receiving a Registration Request message of type “periodic registration update” from a UE, the AMF sends a new 5G-GUTI to the UE in Registration Accept message. Upon receiving a network triggered Service Request Message from a UE, the AMF uses a UE Configuration Update procedure to send a new 5G-GUTI to the UE. The 5G-GUTI has two main components: the Global Unique AMF Identifier (GUAMI) and the 5G-TMSI that provides an unambiguous identity of the UE within the AMF(s) identified by the GUAMI. GUAMI further comprises two network identifiers: PLMN ID and AMF ID. PLMN ID comprises a mobile country code (MCC) and a mobile network code (MNC).

In case of PLMN, the assigned 5G-GUTI is globally unique. When UE moves between PLMNs, UE provides 5G-GUTI in Registration Request to Target AMF. Target AMF derives the information of GUAMI from the provided 5G-GUTI for finding Source AMF which allocates the 5G-GUTI to the UE. As depicted by310, GUAMI (Globally Unique AMF Identifier) contains MCC (Mobile Country Code), MNC (Mobile Network Code) and AMF Identifier. MCC and MNC constitutes a PLMN ID320which is usually unique when assigned by PLMN. Therefore, Target AMF can use the unique GUAMI to find Source AMF for retrieving UE context. In case of SNPN, the PLMN ID of the SNPN in 5G-GUTI is unique within an SNPN, but may not be globally unique when assigned by SNPN. As depicted by310, since the PLMN ID320of SNPN ID (which consists of PLMN ID and NID) may not be globally unique (e.g., the MCC330may be 999 assigned by any SNPN), Target AMF may not be able to find Source AMF using the derived GUAMI from 5G-GUTI assigned by SNPN. Mobility Registration Update procedure may fail. Therefore, when UE moves from SNPN to other network, UE provides 5G-GUTI along with NID in Registration Request to Target AMF. Target AMF derives the information of GUAMI from the provided 5G-GUTI using the provided NID for finding Source AMF which allocates the 5G-GUTI to the UE.

FIG.3Bshows one example of NID assignment based on different Assignment modes. As depicted inFIG.3B, NID350comprises an Assignment mode, a NID PEN, and a NID code. The NID value can be determined based on different Assignment modes as specified in TS 23.003. For example, if Assignment mode is set to 0, then it means the NID is assigned globally unique independent of the PLMN ID of the SNPN. In another example, if Assignment mode is set to 2, then it means the NID is assigned globally unique with the combination of NID and PLMN ID. Note that the NID information here refers to the entire NID value or a partial NID value (e.g., the first digit of the NID value). Providing NID information along with 5G-GUTI can assist the Target AMF to be able to find the Source AMF efficiently, preventing a potential registration procedure failure. The target AMF can use the NID information along with 5G-GUTI to find the source AMF for deriving UE context for the subsequent operations during the mobility registration update procedure.

FIG.4illustrates a mobility registration update procedure where a UE401moves from a source AMF404to a target AMF403, with enhanced NID provisioning in accordance with one novel aspect. In step411, UE401performs initial registration in a source network, e.g., an SNPN having a source AMF404. A UE needs to register with the network to get authorized to receive services, to enable mobility tracking and to enable reachability. The UE initiates the Registration procedure using one of the following Registration types: Initial Registration to the 5GS; Mobility Registration Update upon changing to a new Tracking Area (TA) outside the UE's Registration Area, or when UE needs to update its capability or protocol parameters, etc.; Periodic Registration Update (due to a predefined time period of inactivity); or Emergency Registration; or Disaster Registration; or SNPN Onboarding Registration.

Upon sending an initial registration request to the source AMF404, UE401is assigned by the SNPN a 5G-GUTI, which may not be a globally unique number. The source SNPN can be identified by an SNPN ID, which comprises a PLMN ID and an NID. Later on, UE401moves to a target network, having a target AMF403. The target network can be another SNPN or a PLMN. In step421, UE401triggers a mobility registration update procedure or other NAS procedure. UE401may determine that its 5G-GUTI may not be unique, if it is assigned by the source network that is an SNPN. In response, UE401provides the 5G-GUTI together with the NID information of the source network to the target network during the registration procedure or the other NAS procedure using an existing NAS message or a new NAS message. In one example, UE401sends a Registration Request to the target AMF403. The Registration Request comprises a Registration Type (e.g., Mobility Registration Update); SUCI or 5G-GUTI or PEI; Security parameters; additional GUTI; 4G Tracking Area Update; the indication that the UE is moving from EPS; PLMN with Disaster Condition. If the UE is registered with an SNPN, then the Registration Request further comprises the NID of the SNPN that assigned the 5G-GUTI.

In step422, the target AMF403receives the registration request, derives information of GUAMI from the received 5G-GUTI, and finds the source AMF404accordingly. NID information may also be provided in the registration request. If NID is a self-assigned value (i.e. which value is set to 1 as specified in TS 23.003), the value of PLMN ID (of the 5G-GUTI)+NID may not be (globally) unique. Therefore, target AMF403may need to request UE401to provide UE SUCI/SUPI for the subsequent procedures. If NID is a coordinated assigned value, the value of PLMN ID (of the 5G-GUTI)+NID is (globally) unique. Therefore, target AMF403can use the information along with 5G-GUTI to find the correct source AMF. Upon finding the correct source AMF404, in step431, target AMF403sends a request (Namf_Communication_UEContext_Request) message to source AMF404, requesting UE context information of UE401. In step432, source AMF404sends a response message (Namf_Communication_UEContext_Response) back to target AMF403, providing the UE context information. In step441, a MOBILITY REGISTRATION UPDATE procedure is performed between UE401and other network entities. In step442, target AMF403sends a registration accept message to UE401to complete the registration update.

FIG.5is a flow chart of a method supporting enhanced NID provisioning under UE mobility scenarios between different types of networks from UE perspective in accordance with one novel aspect. In step501, a UE registers to a stand-alone non-public network (SNPN). The SNPN is identified by a Public Land Mobile Network (PLMN) ID and a Network Identifier (NID). In step502, the UE determines that a 5G Global Unique Temporary Identifier (5G-GUTI) is assigned to the UE by the SNPN. In step503, the UE triggers a mobility registration update procedure and transmits a registration request to a target access and mobility function (AMF) of a target network. The registration request comprises the 5G-GUTI and NID information of the SNPN. In step504, the UE performs the mobility registration update procedure with the target network.

FIG.6is a flow chart of a method supporting enhanced NID provisioning under UE mobility scenarios between different types of networks from NW perspective in accordance with one novel aspect. In step601, a network entity (target AMF) receives a registration request from a User Equipment (UE) in a target network. The registration request triggers a mobility registration update procedure. In step602, the target AMF receives a 5G Global Unique Temporary Identifier (5G-GUTI) and Network Identifier (NID) information of a source network. The source network is a stand-alone non-public network (SNPN) identified by a Public Land Mobile Network (PLMN) ID and a NID. In step603, the target AMF determines a source AMF using the received 5G-GUTI and the NID information. In step604, the target AMF performs the mobility registration update procedure for the UE. The target AMF acquires UE context information from the source AMF.

Although the present invention has been described in connection with certain specific embodiments for instructional purposes, the present invention is not limited thereto. Accordingly, various modifications, adaptations, and combinations of various features of the described embodiments can be practiced without departing from the scope of the invention as set forth in the claims.