Network resource selection

Abstract

A method performed by a UE. The method includes receiving from a RAN node system information (SI) including at least a first CN type indicator indicating a first CN type. The method also includes determining whether the first CN type indicated by the first CN type indicator is a desired CN type. The method further includes after determining that the first CN type indicated by the first CN type indicator is a desired CN type, initiating a registration procedure with a first CN via the RAN node, wherein the first CN is a CN of the desired type of CN.

Description

NETWORK RESOURCE SELECTIONTECHNICAL FIELD

[0001] Disclosed are embodiments related to a user equipment (UE) selecting a network resource, such as a cell or a core network (CN).BACKGROUND

[0002] A radio access network node (e.g., a base station or a component of a base station) periodically transmits, for each cell that it serves, system information associated with the cell. The system information associated with a cell includes cell section information, which typically includes at least one Public Land Mobile Network (PLMN) identifier (ID) that identifies a PLMN to which the cell belongs.

[0003] Currently, when a UE, such as a mobile phone or any other device capable of wirelessly communicating with the network node of the radio access network (RAN) (“RAN node”), seeks to gain network access, such as internet access or other network access, the UE searches for a “compatible” cell and connects to a RAN node serving the cell. Typically, when not roaming, the compatible cell is a cell that at least belongs to a PLMN having a PLMN ID that matches a PLMN ID stored in the UE’s subscriber identity module (SIM). When the UE connects to the RAN node, the RAN node selects a network function within a CN, such as a CN belonging to the PLMN identified by the PLMN ID stored in the UE’s SIM, and forwards to the selected network function a registration request the RAN node received from the UE. In this way, the UE can register with the CN. As example, the network function to which the registration request is sent may be a Mobility Management Entity (MME) in an Evolved Packet System (EPS) CN (EPC) or an Access and Mobility Management Function (AMF) within a Fifth Generation System (5GS) CN (5GC).

[0004] A UE can use multiple Data Network Names (DNNs) and / or Access Point Names (APNs) within the CN to establish different user plane sessions. Overall, this means that the following combination of mechanisms are supported in EPS and 5GS for a UE.

[0005] In EPS, first the PLMN is considered and then CN selection using UE Usage Type (if available), as specified for Dedicated Core Network (DECOR); A UE not having a UEUsage Type assigned will connect to an MME in the default network and use that network for all its PDN connections. Different APN is used to for each PDN Connections to select different gateway.

[0006] In 5GS it is possible (but not necessary) for the UE to use different S-NSSAIs for different PDU Sessions, hence it is possible to use more than one network slice in parallel. Using more than one network slice by one UE requires a common AMF in 5GC.

[0007] In EPS, the UE can only have one UE Usage Type and the MME can only use different APNs to select a gateway belonging to different data network. Hence the UE must be correctly configured with these APNs to mimic network slicing on 5GS.

[0008] The RAN can monitor the performance of and manage the resources per network slice based on S-NSSAI. The RAN can use and monitor different resources e.g., in case the UE uses different S-NSSAIs for different PDU sessions.

[0009] Which PLMNs, UE Usage Types, S-NSSAIs and APN / DNNs are supported is decided based on business needs, either on already instantiated (semi-static) Network Slice Instances (NSIs) or on dynamically instantiated NSIs for a customer.SUMMARY

[0010] Certain challenges presently exist. For instance, is it possible that a single PLMN can have two or more CNs, such as a first CN of a first type and a second CN of a second type, and it is further possible that a UE may prefer to register with the second CN rather than the first CN, but there is presently no standard way for the RAN node to determine the CN with which the UE would like to register. Hence, the RAN node may not forward the registration request to the UE’s preferred CN.

[0011] Accordingly, in one aspect there is provided a method performed by a UE. The method includes receiving from a RAN node system information (SI) including at least a first CN type indicator indicating a first CN type. The method also includes determining whether the first CN type indicated by the first CN type indicator is a desired CN type. The method further includes after determining that the first CN type indicated by the first CN type indicator is a desired CN type, initiating a registration procedure with a first CN via the RAN node, whereinthe first CN is a CN of the desired type of CN. In another aspect there is provided a UE configured to perform this method.

[0012] In another aspect there is provided a method performed by a RAN node. The method includes transmitting the SI including the first CN type indicator indicating a first CN type. In another aspect there is provided a RAN node configured to perform this method.

[0013] In another aspect there is provided a method performed by a CN node. The method includes the CN node transmitting to the RAN node the first CN type indicator. In another aspect there is provided a CN node configured to perform this method.

[0014] In another aspect there is provided a computer program comprising instructions which when executed by processing circuitry of an apparatus causes the apparatus to perform any of the methods disclosed herein. In one embodiment, there is provided a carrier containing the computer program wherein the carrier is one of an electronic signal, an optical signal, a radio signal, and a computer readable storage medium.

[0015] An advantage of the embodiments disclosed herein is that they enable a UE to be registered with the CN that is preferred by the UE.BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The accompanying drawings, which are incorporated herein and form part of the specification, illustrate various embodiments.

[0017] FIG. 1 illustrates a system according to an embodiment.

[0018] FIG. 2 is a message flow diagram illustrating a message flow according to an embodiment.

[0019] FIG. 3 illustrates functional components of a UE.

[0020] FIG. 4 is a flowchart illustrating a process according to an embodiment.

[0021] FIG. 5 is a flowchart illustrating a process according to an embodiment.

[0022] FIG. 6 is a flowchart illustrating a process according to an embodiment.

[0023] FIG. 7 a block diagram of UE according to an embodiment.

[0024] FIG. 8 a block diagram of RAN node according to an embodiment.

[0025] FIG. 9 a block diagram of CN node according to an embodiment.DETAILED DESCRIPTION

[0026] FIG. 1 illustrates a system 100 according to an embodiment. System 100 includes a UE 102 (i.e., any device capable of communicating with a RAN node), a RAN node 104, a first CN 106, and a second CN 108. As shown in FIG. 1, CN 106 includes at least one network function (NF) 111 (e.g., an AMF) and CN 108 includes at least one NF 112 (e.g. an AMF). While only one UE, one RAN node, on NF per CN, and two CNs are shown in FIG. 1, this is was only done for the sake of brevity as it is well known that system 100 may have many UEs, many RAN nodes connected to the same set of CNs or a different set of CNs, and many CNs, with each CN comprising many NFs. CN 106 and CN 108 may be owned by the same owner and / or operated by the same operator, but this is not a requirement. However, in this example, CN 106 is a first type of CN (e.g., a data plane CN, an extended reality (XR) CN, an offload CN, etc.) and CN 108 is a second type of CN that is different than the first type. That is, CN 108 may provide different services that CN 106.

[0027] As noted above, when UE 102 seeks to gain network access for certain traffic (or all traffic from the UE), UE 102 searches for a “compatible” cell and connects to a RAN node serving the cell. In this example, RAN node 104 serves such a compatible cell and UE 102 establishes a connection with RAN node 104, such as, for example, a Radio Resource Control (RRC) connection. When UE 102 connects to RAN node 104, RAN node 104 selects a CN (i.e., a CN in a PLMN to which the cell belongs) and forwards to a selected network function within the selected CN the registration request the RAN node received from the UE, and, in this way, UE 102 can register with a CN. The problem arises when the UE has a preference for the type of CN that it wants to register with. For example, for the sake of illustration, one can assume that UE 102 prefers, based on, for example, configuration information such as e.g. a route selection rule, to register with CN 108 and not CN 106. But, conventionally, RAN node 104 does not have enough information to deterministically select the CN preferred by UE 102.

[0028] Accordingly, this disclosure describes an embodiment in which the RAN and UE communication is extended so that not only PLMN ID is used by the UE to make a cell selection. For example, RAN node 104 is configured to broadcast cell selection information that includes, in addition to a PLMN ID, a CN type indicator indicating a CN type (e.g., a data plane CN,extended reality (XR) CN, offload CN, etc.), and UE 102 is configured to determine whether the CN type indicated by CN type indicator is a desired CN type. If it is a desired CN type, UE 102 initiates a registration procedure with a CN via RAN node 104, wherein the CN is a CN of the desired type of CN. The CN type indicator may be a CN type ID that specifies the CN type and / or a CN ID that identifies a specific CN of the CN type. In this way, UE 102 can request which CN type (and / or CN ID) it wants to connect to depending on the service needs. As described herein, for each CN to which RAN node 104 is connected, the RAN node can obtain the CN type indicator that the RAN node includes in the SI from an AMF in the CN using for example the NG Setup procedure.

[0029] In one embodiment, UE 102 is configured to initiate the registration procedure by transmitting to RAN node 102 an access stratum message (e.g., RRC message) comprising the CN ID and / or CN type ID and a non-access stratum (NAS) message (e.g., a registration request message) to be forwarded by the RAN node 104 to a network function. RAN node 104 selects the network function based on the CN ID and / or CN type ID included in the message (e.g., RRC message) from UE 102. In this way, RAN node 104 can select a network function within a CN of the type preferred by UE 102.

[0030] Extension of System Information (SI) Broadcast by RAN node 104.

[0031] SI Block 1 (SIB1) message

[0032] The SIB1 message (or “SIB1” for short) contains information relevant when evaluating if a UE is allowed to access a cell and defines the scheduling of other system information. It also contains radio resource configuration information that is common for all UEs, and barring information applied to the unified access control. Table 1 below illustrates an example SIB1 message.TABLE 1

[0033] As shown table 1 above, SIB1 includes an information element (IE) containing cell access related information. This IE is named “cellAccessRelatedlnfo.” Table 2 below provides an example of the IES that may be included in the cellAccessRelatedlnfo IE.TABLE 2

[0034] As shown table 2 above, the CellAccessRelatedlnfo includes a IE containing a list of PLMN identify information. This IE is named “plmn-IdentifylnfoList.” Table 3 below provides an example of the IES that may be included in the plmn-IdentifylnfoList IE.TABLE 3

[0035] As shown in table 3, the plmn-IdentifylnfoList IE optionally includes an IE containing one or more CN type IDs (this IE is named CN TypeList) and an IE containing one or more CN IDs (this IE is named CN Identity). In one embodiment, the CN Identity list IE shall list the CN Identities in the same order as the CN types (e.g., matching pairs received from a core network function, such as an AMF).

[0036] In another embodiment, the CN TypeList and CN Identity IES can be replaced with the following structure shown in table 4:TABLE 4

[0037] FIG. 2 show RAN node 104 broadcasting the above described system information (SI) (see SI message m201) (as is well known in the art, broadcast SI is not UE specified). By RAN node 104 broadcasting the above-described SI, RAN node 104 enables UE 102, which receives the SI, to determine whether or not a particular cell served by RAN node 104 is associated with a CN of the UE’s preferred CN type. If UE 102 determines that a particular cell served by RAN node 104 can be used by the UE to access the UE’s preferred CN type, then UE may initiate a registration procedure with the CN via RAN node 104.

[0038] Establishing Radio Connection and Initiating the Registration Procedure

[0039] In one embodiment, UE 102 is configured such that, prior to initiating the registration procedure with its preferred CN via RAN node 104, UE 102 initiates the establishment of a connection with RAN node 104. In one embodiment, UE 102 initiates the establishment of the connection with RAN node 104 by transmitting a connection request m203 (see FIG. 2), such as, for example, an RRCConnectionRequest message as is known in the art. In response to the connection request, RAN node may transmit to UE 102 a connection setup request m205, such as, for example, an RRCConnectionSetup message as is known the art, and UE 102 may respond to the connection setup request by transmitting to RAN node 104 aconnection setup complete message m207, such as, for example, a modified version of the conventional RRCSetupComplete message. In one embodiment, transmitting the connection setup complete message initiates the registration procedure with the CN. Each of the message mentioned in this paragraph is a type of access stratum (AS) message.

[0040] An example of a modified version of the conventional RRCSetupComplete message is shown in table 5 below.TABLE 5 - RRC Setup Complete

[0041] The example modified version of the conventional RRCSetupComplete message shown above includes a CN type ID and / or a CN ID. The CN type ID and / or CN ID convey the selected CN to RAN node 104, and this allows RAN node 104 to base its CN selection on UE 102’s CN selection. Note that the above description is not made in a backwards compatible way. To make the above backwards compatible, the “cN-TypeAndOr!dentity“ could be added as part of the “nonCriticalExtens ion”.

[0042] As shown above in Table 5, the setup complete message may include a dedicated non-access stratum (NAS) message m209 (see the IE named dedicatedNAS-message). In one embodiment, dedicated NAS message m209 is or comprises a registration request message, and RAN node 104 is configured to forward the dedicated NAS message m209 to a CN network function (e.g., NF 111 in the example shown in FIG. 2) selected based on the CN type indicator included in the setup complete message. In this way, the UE’s registration request message will get routed to a NF within a CN of the type preferred by the UE.

[0043] Core Network Coordination

[0044] In some embodiment, the UE is capable of dual registration. That is, the UE is capable of simultaneously being registered with a first NF in a first CN (e.g., NF 111) and a second NF in a second CN (e.g., NF 112). Accordingly, in this embodiment, the registration request message m209 included in the setup complete message m2207 may be a modified version of an existing registration request message. An example of a modified version of the currently existing registration request message is shown in table 6 below.TABLE 6 - Registration Request

[0045] As shown in Table 6, in one embodiment, the registration request message includes not only information indicating the type of registration being requested (“5GS registration type”), but also an indicator (e.g., a Boolean flag) that indicates that the UE is capable of dual registration. The UE also includes information on the selected CN (CN type ID and / or a CN ID). Furthermore, if the UE is currently registered with a NF (e.g., NF 112) at the time the UE sends the registration request m209 (i.e., the UE is seeking dual registration), then the registration request message may include the ID of the NF 112.

[0046] The purpose of the 5GS registration type IE (see above table) is to indicate the type of the requested registration. In one embodiment, the 5GS registration type is an information element with a length of 1 octet (8 bits). In one embodiment, the first three bits encode a registration type value, the fourth bit is a follow on request bit indicating whether or not a follow-on request is pending, the fifth bit is a secondary core request bit indicating whether or not the UE is currently registered with a CN, and the remaining bits are an IE ID.

[0047] After NF 111 (e.g., AFM) receives the registration request message m209, the NF will obtain subscription data associated with the 5GS mobile identity included in the registration request message. The NF 111 may obtain the subscription data by transmitting to a Unified Data Management (UDM) a request message m211 requesting the subscription data and responds a response message m213 containing the requested subscription data. NF 111 will check that thesubscription data authorizes the NF to register the UE. For example, the subscription data may include an indicator named “dualRegistrationAllowed” (e.g., a Boolean flag) indicating whether or not dual registration is allowed for the UE, a list of one or more allowed or not-allowed CN IDS, and / or a list of one or more allowed or not-allowed CN types. These features are illustrated in Table 7, which shows an example of the subscription data that the NF 111 will obtain. Based on the subscription data, the NF 111 can decide whether or not to accept or reject the registration request. For instance, if the subscription data includes the list of allowed CN IDs and the CN ID of the CN the UE is attempting to register with is not on the allowed CN ID list, then the NF 111 may choose to reject the registration request. Likewise, if the secondary core request bit mentioned above indicates that the UE is currently registered with a CN and the dualRegistrationAllowed bit in the subscription data specifies that dual registration is not allowed, then the NF 111 should reject the registration request.TABLE 7 - Subscription Data

[0048] As sown in Table 7, the subscription day may include IES named “cnTypesAllowed” and “cnldentitiesAllowed” which contain a list of allowed CN types and a list of allowed CN IDs, respectively.

[0049] After determining to accept the registration request, NF 111 may send to UDM 202 an update request m215 to update the NF registration information. The request contains the UE's identity ( / {ueld}) which may be a permanent identifier (e.g,. a Subscriber Permanent ID (SUPI) and the NF registration information.

[0050] For example, in one embodiment, the update request m215 is an Hypertext Transfer Protocol (HTTP) PUT request to update or create registration information for UE 102. The NF 111 shall include ueReachablelnd IE if the UE is currently not reachable (e.g. in not allowed areas) or the UE reachability is unknown (e.g. service restriction area of the UE is not received at the NF 111 during initial registration). The NF 111 shall include the "backupAMFInfo" IE containing all of the GUAMI served by the NF 111 and the related backup NF 111 name if the NF 111 supports the management without UDSF. The NF 111 shall include an ExistingRegistration IE in the update request message if the registration request message m209 indicates that the UE is currently registered with another NF (e.g., NF 112 in this example).

[0051] On success, the UDM updates the relevant resource by replacing it with the received resource information, and responds with message m216 (e.g., "200 OK" or "204 No Content").

[0052] If the ExistingRegistration IE is missing and the UDM is aware that the UE is currently registered with NF 112, then the UDM may invoke the Deregistration Notification service operation towards NF 112 using the callback URI provided by NF 112. If the ExistingRegistration IE is included, then the UDM may mark the two registered NFs as “primary” and “secondary” NFs. For example, UDM may mark NF 111 as the secondary NF and NF 112 as the primary NF because UE was already registered with NF 112 at the time NF 111 received the registration request m209. The UDM may inform the primary NF 112 about the secondary NF 111 identity in a Notification procedure. In this way the inter NF mobilitycontinues to work. The ExistingRegistration IE may include an indication indicating that NF 111 should be the primary or indicating that NF 112 should be the primary.

[0053] If the NF 111 decides to accept the registration request, the NF 111 transmits a registration accept message m217 to UE 102 via RAN node 104. The registration accept message m217 may include an indication on the CN type and / or CN identity for which the registration is accepted and may also include the ID of NF 111, as shown in Table 8 below which shows the content of the registration accept message in one embodiment.TABLE 8 - REGISTRATION ACCEPT message content

[0054] USRP Rules Enhancement

[0055] As described above, UE 102 may be configured to select a cell based on a desiredCN type. In one embodiment, as shown by the dotted line in FIG. 2, a policy function (PF) 204 (e.g., a 5GS Policy Control Function (PCF)) provides to UE 102 an enhanced UE Route Selection Policy (URSP) rule that identifies a preferred CN type. In this way, when UE 102 receives the SI message m201, UE 102 can determine whether the SI message identifies a desired CN type by determining whether the CN type indicator included in the SI message matches the CN type indicated in the URSP rule. Table 9 illustrates the information included in a URSP rule according to an embodiment.TABLE 9 - UE Route Selection Policy (URSP) Rule

[0056] As shown in Table 9, the URSP rule includes at least one Route SelectionDescriptor. The information included in the RSD, according to one embodiment, is shown below in Table 10.TABLE 10

[0057] In one embodiment, the following steps are performed:

[0058] (1) PF 204 subscribes to the NF 112 for notifying N1 messages of the UE PolicyDelivery Results;

[0059] (2) PF 204 sends the determined URSP rule using the Namf_Communication_NlN2MessageTransfer service operation and the message contains the NIMessageClass IE set to UPDP and the UE Policy Container containing the URSP rule; if the Namf_Communication_NlN2MessageTransfer Request message is received during a registration procedure, the NF 112 sends the 200 OK HTTP status code in the Namf_Communication_NlN2MessageTransfer Response message to PF 204 and buffers the UEPolicy Container; when the Registration Complete message is received, the NF 112 sends the Downlink NAS Transport message with the UE Policy Container to the UE;

[0060] 3. If the UE is in the CM-IDLE state, the NF 112 initiates a Network TriggeredService Request procedure to establish a signaling connection with the UE;

[0061] 4. The NF 112 sends a Downlink NAS Transport message containing NAS PDUIE to RAN node 104;

[0062] 5. RAN node 104 sends a DL NAS Transport message to the UE; the message contains the UE Policy Container, which contains the URSP rule;

[0063] 6. UE 102 sends an UL NAS Transport message to RAN node 104; the message contains the UE Policy Container;

[0064] 7. RAN node 104 sends an Uplink NAS Transport message containing NAS PDUIE to the NF 112; and

[0065] 8. NF 112 sends the N1 message received from the UE to PF 204 using theNamf_Communication_NlMessageNotify service operation, if PF 204 has successfully subscribed to notification of UE Policy Delivery Results in step 1.

[0066] Once the UE has received the URSP rule, UE 102 can select a cell according to the Route Selection Descriptor. This is illustrated in FIG. 3.

[0067] FIG. 3 shows UE 102 hosting an application (app) 301, which provides to the UE’s operations system (OS) 303 a request to have a connection established. The OS provides a traffic descriptor (e.g., the ID of app 301) to a NAS layer 305 within UE 102. The UE 102 maps the traffic descriptor to a Traffic Category ID. NAS layer 305 then uses the Traffic Category ID to find the URSP rule corresponding to the Traffic Category ID. The UE can then use the URSP rule to select a cell as described above and connect to the RAN node serving the cell. After connecting to the RAN node, the UE registers with a NF as described above and establishes a PDU session for the traffic to / from app 301. In this way, the URSP is used not only for PDU session management, but also for mobility management making it possible to use the URSP for the registration procedure.

[0068] NG Setup

[0069] An NG Setup procedure or similar can be used so that RAN node 104 can obtain the CN type indicator to include in the broadcast SI. Besides NG Setup, AMF Configuration Update can be used for AMF dynamic updates of the new parameters provided in NG Setup procedure as shown below.

[0070] RAN node 104 initiates the procedure by sending an NG SETUP REQUEST message including the appropriate data to a NF. The NF responds with an NG SETUP RESPONSE message including the appropriate data. More specifically, RAN nodes performs the procedure with all CNs. For example, for each CN to which RAN node 104 is connected, RAN node 104 will send the NG SETUP REQUEST message including the appropriate data to a NF in the CN.

[0071] The NF responds by sending to the RAN node a NG SETUP RESPONSE message comprising: 1) a list of CN type IDs, where each CN type ID identifies a CN type supported by the NF, and 2) a list of CN IDs, wherein each CN ID identifies a CN supported by the NF. The RAN node 104 shall store this information and further use it (e.g., include in the SI as described above) for NF selection for the dual stack UE.

[0072] FIG. 4 is a flow chart illustrating a process 400, according to an embodiment, that is performed by UE 102. Process 400 may begin in step s402.

[0073] Step s402 comprises receiving from RAN node 104 SI including at least a first CN type indicator indicating a first CN type. In one embodiment, the SI is broadcast by RAN node 104.

[0074] Step s404 comprises determining whether the first CN type indicated by the first CN type indicator is a desired CN type.

[0075] Step s406 comprises, after determining that the first CN type indicated by the first CN type indicator is a desired CN type, initiating a registration procedure with a first CN via the RAN node, wherein the first CN is a CN of the desired type of CN.

[0076] In some embodiments, the CN type indicator consists of a CN ID identifying a CN of the first CN type (thereby indicating the first CN type), the UE is configured to initiate the registration procedure with the first CN by transmitting to the RAN node an access stratum message comprising a non-access stratum message (e.g., a registration request message) to beforwarded by the RAN node to a network function (e.g., an access management function) within the first CN, and the access stratum message comprises the CN identifier and a CN type identifier identifying the first CN type.

[0077] In some embodiments, the CN type indicator comprises a first CN ID identifying the first CN and / or a first CN type ID identifying the first CN type, the UE is configured to initiate the registration procedure with the first CN by transmitting to the RAN node an access stratum message comprising a non-access stratum message (e.g., a registration request message) to be forwarded by the RAN node to a network function within the first CN, and the access stratum message comprises the first CN ID and / or the first CN type ID.

[0078] In some embodiments, the broadcast system information contains radio resource configuration information that is common for all UEs, and barring information applied to a unified access control, the broadcast system information pertains to at least a first cell of the RAN that is served by the RAN node, the broadcast system information comprises a cell access related information, CARI, information element, IE, that indicates cell access related information for the first cell, and the first CN type indicator is included within the CARI IE.

[0079] In some embodiments, the CARI IE comprises public land mobile network, PLMN, identity information, and the PLMN identity information comprises: one or more PLMN identifiers; and the first CN type indicator.

[0080] In some embodiments, the PLMN identity information further comprises a first CN identifier, ID, and the CN ID identifies a CN of the type indicated by the first CN type indicator.

[0081] In some embodiments, the UE is configured such that, after determining that the first CN type indicated by the first CN type indicator is a desired CN type but prior to initiating the registration procedure with the first CN, the UE initiates the establishment of a connection with the RAN node, and the UE is configured to initiate the registration procedure with the first CN by transmitting to the RAN node an access stratum message comprising a non-access stratum message (e.g., a registration request message) to be forwarded by the RAN node to a network function (e.g., an access management function) within the first CN.

[0082] In some embodiments, initiating the establishment of the connection with the RAN node comprises the UE transmitting to the RAN node a connection setup request.

[0083] In some embodiments, the access stratum message is a connection setup complete message.

[0084] In some embodiments, the access stratum message comprises the first CN type indicator or a CN identifier that identifies a CN of the type indicated by the first CN type indicator.

[0085] In some embodiments, the system information further comprises a first public land mobile network, PLMN, identifier, the UE is further configured to determine whether the first PLMN ID identifies a desired PLMN, and the UE initiates the registration with the first CN of the desired type of CN via the RAN node after determining that the first CN type indicated by the first CN type indicator is a desired CN type and that the first PLMN ID identifies a desired PLMN.

[0086] In some embodiments, the UE is currently registered with a second CN of a type different than the first CN at the time the UE initiates the registration with the first CN. In some embodiments, the first and second CNs belong to the same Public Land Mobile Network (PLMN).

[0087] In some embodiments, the UE receives from the second CN a UE route selection policy, URSP, rule, and the UE is configured to determine whether the first CN type indicated by the first CN type indicator is a desired CN type based on the URSP rule.

[0088] In some embodiments, the URSP rule comprises a route selection descriptor indicating the desired CN type, the UE is configured to determine whether the first CN type indicated by the first CN type indicator is a desired CN type based on the route selection description included in the URSP rule.

[0089] In some embodiments, the UE initiates the registration with the first CN by transmitting a registration request message, and the registration request message indicates that the UE is currently registered in another CN.

[0090] In some embodiments, the registration request comprises information for identifying the second CN and / or a network function operating within the second CN.

[0091] In some embodiments, the UE is further configured to obtain the information for identifying the second CN and / or the network function operating within the second CN from a NAS message (e.g., registration accept message) transmitted by the network function operating in the second CN.

[0092] FIG. 5 is a flow chart illustrating a process 500, according to an embodiment, that is performed by RAN node 104. Process 500 may begin in step s502. Step s502 comprises transmitting system information (SI) including at least a first CN type indicator indicating a first CN type. Process 500 may also include step s504, which comprises receiving from UE 102 an access stratum message comprising a NAS message (e.g., a registration request message) and CN selection information comprising the first CN type identifier or a CN identifier that identifies a CN of the type indicated by the first CN type identifier. Process 500 may further includes step s506, which comprises RAN node 104 forwarding the NAS message based on the CN selection information.

[0093] FIG. 6 is a flow chart illustrating a process 600, according to an embodiment, that is performed by a CN node 900 (see FIG. 9). Process 600 may begin in step s602. Step s602 comprises CN node 900 transmitting to RAN node 104 a CN type indicator indicating a particular CN type. Process 600 may also includes step s604, which comprises CN node 900 transmitting a NAS message to UE 102, which was registered by the CN node, wherein the NAS message comprises a URSP rule comprising a CN type indicator, thereby enabling the UE to determine, based on the URSP rule, whether a CN type indicated by a CN type indicator transmitted by a node of the RAN is a desired CN type.

[0094] FIG. 7 is a block diagram of UE 102, according to some embodiments. As shown in FIG. 7, UE 102 may comprise: processing circuitry (PC) 702, which comprises one or more processors (P) 755 (e.g., one or more general purpose microprocessors and / or one or more other processors, such as an application specific integrated circuit (ASIC), field-programmable gate arrays (FPGAs), and the like); communication circuitry 748, which is coupled to an antenna arrangement 749 comprising one or more antennas and which comprises a transmitter (Tx) 745 and a receiver (Rx) 747 for enabling UE 102 to transmit data and receive data (e.g., wirelessly transmit / receive data); and a storage unit (a.k.a., “data storage system”) 708, which may include one or more non-volatile storage devices and / or one or more volatile storage devices. Inembodiments where PC 702 includes a programmable processor, a computer readable storage medium (CRSM) 742 may be provided. CRSM 742 may store a computer program (CP) 743 comprising computer readable instructions (CRI) 744. CRSM 742 may be a non-transitory computer readable medium, such as, magnetic media (e.g., a hard disk), optical media, memory devices (e.g., random access memory, flash memory), and the like. In some embodiments, the CRI 744 of computer program 743 is configured such that when executed by PC 702, the CRI causes UE 102 to perform steps described herein (e.g., steps described herein with reference to the flow charts). In other embodiments, UE 102 may be configured to perform steps described herein without the need for code. That is, for example, PC 702 may consist merely of one or more ASICs. Hence, the features of the embodiments described herein may be implemented in hardware and / or software.

[0095] FIG. 8 is a block diagram of RAN node 104, according to some embodiments for performing the base station methods disclosed herein. As shown in FIG. 8, RAN node 104 may comprise: processing circuitry (PC) 802, which comprises one or more processors (P) 855 (e.g., a general purpose microprocessor and / or one or more other processors, such as an application specific integrated circuit (ASIC), field-programmable gate arrays (FPGAs), and the like), which processors may be co-located in a single housing or in a single data center or may be geographically distributed (i.e., base station may be a distributed computing system comprising two or more computers or a monolithic computing system consisting of a single computer); a network interface 868 comprising a transmitter (Tx) 865 and a receiver (Rx) 867 for enabling RAN node 104 to transmit data to and receive data from other nodes connected to a network 110 (e.g., an Internet Protocol (IP) network) to which network interface 868 is connected; communication circuitry 848 (e.g., radio transceiver circuitry comprising an Rx 847 and a Tx 845) coupled to an antenna system 849 for wireless communication with UEs or other nodes; and a storage unit (a.k.a., “data storage system”) 808, which may include one or more non-volatile storage devices and / or one or more volatile storage devices. In embodiments where PC 802 includes a programmable processor, a computer readable storage medium (CRSM) 842 may be provided. CRSM 842 may store a computer program (CP) 843 comprising computer readable instructions (CRI) 844. CRSM 842 may be a non-transitory computer readable medium, such as, magnetic media (e.g., a hard disk), optical media, memory devices (e.g., random access memory, flash memory), and the like. In some embodiments, the CRI 844 of computer program 843 isconfigured such that when executed by PC 802, the CRI causes RAN node 104 to perform steps described herein (e.g., steps described herein with reference to one or more flow charts). In other embodiments, RAN node 104 may be configured to perform steps described herein without the need for code. That is, for example, PC 802 may consist merely of one or more ASICs. Hence, the features of the embodiments described herein may be implemented in hardware and / or software.

[0096] FIG. 9 is a block diagram of a CN node 900, according to some embodiments, which can be used to implement any of the NFs described herein. In embodiments where an NF consists of software, CN node 9 may run (or execute a virtual machine that runs) the NF. As shown in FIG. 9, CN node 900 may comprise: processing circuitry (PC) 902, which comprises one or more processors (P) 955 (e.g., one or more general purpose microprocessors and / or one or more other processors, such as an application specific integrated circuit (ASIC), field- programmable gate arrays (FPGAs), and the like), which processors may be co-located in a single housing or in a single data center or may be geographically distributed (e.g., CN node 900 may be a distributed, cloud computing system comprising two or more computers or a monolithic computing system consisting of a single computer); at least one network interface 948 (e.g., a physical interface or air interface) comprising a transmitter (Tx) 945 and a receiver (Rx) 947 for enabling CN node 900 to transmit data to and receive data from other nodes connected to network 110 (e.g., an Internet Protocol (IP) network) to which network interface 948 is connected (physically or wirelessly) (e.g., network interface 948 may be coupled to an antenna arrangement comprising one or more antennas for enabling CN node 900 to wirelessly transmit / receive data); and a storage unit (a.k.a., “data storage system”) 908, which may include one or more non-volatile storage devices and / or one or more volatile storage devices. In embodiments where PC 902 includes a programmable processor, a computer readable storage medium (CRSM) 942 may be provided. CRSM 942 may store a computer program (CP) 943 comprising computer readable instructions (CRI) 944. CRSM 942 may be a non-transitory computer readable medium, such as, magnetic media (e.g., a hard disk), optical media, memory devices (e.g., random access memory, flash memory), and the like. In some embodiments, the CRI 944 of computer program 943 is configured such that when executed by PC 902, the CRI causes CN node 900 to perform steps described herein (e.g., steps described herein with reference to the flow charts). In other embodiments, CN node 900 may be configured to performsteps described herein without the need for code. That is, for example, PC 902 may consist merely of one or more ASICs. Hence, the features of the embodiments described herein may be implemented in hardware and / or software.

[0097] While various embodiments are described herein, it should be understood that they have been presented by way of example only, and not limitation. Thus, the breadth and scope of this disclosure should not be limited by any of the above-described exemplary embodiments. Moreover, any combination of the above-described elements in all possible variations thereof is encompassed by the disclosure unless otherwise indicated herein or otherwise clearly contradicted by context.

[0098] As used herein transmitting a message “to” or “toward” an intended recipient encompasses transmitting the message directly to the intended recipient or transmitting the message indirectly to the intended recipient (i.e., one or more other nodes are used to relay the message from the source node to the intended recipient). Likewise, as used herein receiving a message “from” a sender encompasses receiving the message directly from the sender or indirectly from the sender (i.e., one or more nodes are used to relay the message from the sender to the receiving node). Further, as used herein “a” means “at least one” or “one or more.”

[0099] Additionally, while the processes described above and illustrated in the drawings are shown as a sequence of steps, this was done solely for the sake of illustration. Accordingly, it is contemplated that some steps may be added, some steps may be omitted, the order of the steps may be re-arranged, and some steps may be performed in parallel.

Claims

CLAIMS1. A user equipment, UE (102), the UE (102) comprising: a receiver (847) for receiving from radio access network, RAN, node (104) system information including at least a first core network, CN, type indicator indicating a first CN type, wherein the UE (102) is configured to: determine whether the first CN type indicated by the first CN type indicator is a desired CN type; and after determining that the first CN type indicated by the first CN type indicator is a desired CN type, initiate a registration procedure with a first CN (106,108) via the RAN node, wherein the first CN is a CN of the desired type of CN.

2. The UE of claim 1, wherein the system information is broadcast by the RAN node.

3. The UE of claim 2, wherein the CN type indicator comprises a first CN identifier, ID, identifying the first CN and / or a first CN type ID identifying the first CN type, the UE is configured to initiate the registration procedure with the first CN by transmitting to the RAN node an access stratum message comprising a non-access stratum message to be forwarded by the RAN node to a network function within the first CN, and the access stratum message comprises the first CN ID and / or the first CN type ID.

4. The UE of claim 2 or 3, wherein the broadcast system information contains radio resource configuration information that is common for all UEs, and barring information applied to a unified access control, the broadcast system information pertains to at least a first cell of the RAN that is served by the RAN node, the broadcast system information comprises a cell access related information, CARI, information element, IE, that indicates cell access related information for the first cell, and the first CN type indicator is included within the CARI IE.

5. The UE of claim 4, wherein the CARI IE comprises public land mobile network, PLMN, identity information, and the PLMN identity information comprises: one or more PLMN identifiers; and the first CN type indicator.

6. The UE of claim 5, wherein the PLMN identity information further comprises a first CN identifier, ID, and the first CN ID identifies a CN of the type indicated by the first CN type indicator.

7. The UE of any one of the preceding claims, wherein the UE is configured such that, after determining that the first CN type indicated by the first CN type indicator is a desired CN type but prior to initiating the registration procedure with the first CN, the UE initiates the establishment of a connection with the RAN node, and the UE is configured to initiate the registration procedure with the first CN by transmitting to the RAN node an access stratum message comprising a non-access stratum message to be forwarded by the RAN node to a network function within the first CN.

8. The UE of claim 7, wherein initiating the establishment of the connection with the RAN node comprises the UE transmitting to the RAN node a connection setup request.

9. The UE of claim 7 or 8, wherein the access stratum message is a connection setup complete message.

10. The UE of claim 9, wherein the access stratum message comprises the first CN type indicator or a CN identifier that identifies a CN of the type indicated by the first CN type indicator.

11. The UE of any one of the preceding claims, wherein the system information further comprises a first public land mobile network, PLMN, identifier,the UE is further configured to determine whether the first PLMN ID identifies a desired PLMN, and the UE initiates the registration with the first CN of the desired type of CN via the RAN node after determining that the first CN type indicated by the first CN type indicator is a desired CN type and that the first PLMN ID identifies a desired PLMN.

12. The UE of any one of the preceding claims, wherein the UE is currently registered with a second CN of a type different than the first CN at the time the UE initiates the registration with the first CN.

13. The UE of claim 12, wherein the UE receives from the second CN a UE route selection policy, URSP, rule, and the UE is configured to determine whether the first CN type indicated by the first CN type indicator is a desired CN type based on the URSP rule.

14. The UE of claim 13, wherein the URSP rule comprises a route selection descriptor indicating the desired CN type, the UE is configured to determine whether the first CN type indicated by the first CN type indicator is a desired CN type based on the route selection description included in the URSP rule.

15. The UE of any one of claims 12-14, wherein the UE initiates the registration with the first CN by transmitting a registration request message, and the registration request message indicates that the UE is currently registered in another CN.

16. The UE of claim 15, wherein the registration request comprises information for identifying the second CN and / or a network function operating within the second CN.

17. The UE of claim 16, wherein the UE is further configured to obtain the information for identifying the second CN and / or the network function operating within the second CN from a NAS message transmitted by the network function operating I the second CN.

18. A radio access network, RAN, node (104), the RAN node (104) being configured to: transmit system information including at least a first core network, CN, type indicator indicating a first CN type.

19. The RAN node of claim 18, wherein the system information further comprises a first public land mobile network, PLMN, identifier.

20. The RAN node of claim 19, wherein the RAN node is configured to broadcast the system information.

21. The RAN node of claim 20, wherein the broadcast system contains radio resource configuration information that is common for all UEs and barring information applied to a unified access control.

22. The RAN node of any one of claims 18-21, wherein the broadcast system information pertains to at least a first cell of the RAN that is served by the RAN node, the broadcast system information comprises a cell access related information, CARI, information element, IE, that indicates cell access related information for the first cell, and the first CN type indicator is included within the CARI IE.

23. The RAN node of claim 22, wherein the CARI IE comprises public land mobile network, PLMN, identity information, and the PLMN identity information comprises: one or more PLMN identifiers; and the first CN type indicator.

24. The RAN node of claim 23, wherein the PLMN identity information further comprises a first CN identifier, ID, and the CN ID identifies a CN of the type indicated by the first CN type indicator.

25. The RAN node of any one of claims 18-24, wherein the RAN node is further configured to receive from a UE an access stratum message comprising a non-access stratum message, the access stratum message comprises CN selection information, wherein the CN selection information comprises the first CN type identifier, ID, or a CN ID that identifies a CN of the type indicated by the first CN type ID, and the RAN node is further configured to forward the non-access stratum message based on the CN selection information.

26. The RAN node of claim 25, wherein the access stratum message is a connection setup complete message.

27. The RAN node of claim 26, wherein the access stratum message comprises the first CN type indicator.

28. The RAN node of any one of claims 25-27, wherein the RAN node is further configured such that, prior to the RAN node transmitting the system information, the RAN node transmits to the UE an access stratum message comprising a NAS message comprising a UE route selection policy, URSP, rule, thereby enabling the UE to determine, based on the URSP rule, whether the CN type indicated by the CN type indicator is a desired CN type.

29. A core network, CN, node (900) operating in a CN (106, 108) of a particular CN type, the CN node being configured to: transmit to a radio access network, RAN, node (104) a CN type indicator indicating said particular CN type.

30. The CN node of claim 29, wherein the CN node is further configured to transmit a NAS message to a UE registered with the CN node, wherein the NAS message comprises a UE route selection policy, URSP, rule comprising a CN type indicator, thereby enabling the UE to determine, based on the URSP rule, whether a CN type indicated by a CN type indicator transmitted by the RAN node is a desired CN type.

31. A method (400) performed by a user equipment, UE (102), the method comprising: receiving (s402) from radio access network, RAN, node (104) system information, SI(m201), including at least a first core network, CN, type indicator indicating a first CN type; determining (s404) whether the first CN type indicated by the first CN type indicator is a desired CN type; and after determining that the first CN type indicated by the first CN type indicator is a desired CN type, initiating (s406) a registration procedure with a first CN via the RAN node, wherein the first CN is a CN of the desired type of CN.

32. The method of claim 31, wherein the system information is broadcast by the RAN node, the CN type indicator comprises a CN ID identifying the first CN and / or a first CN type ID identifying the first CN type, the UE is configured to initiate the registration procedure with the first CN by transmitting to the RAN node an access stratum message comprising a non-access stratum message to be forwarded by the RAN node to a network function within the first CN, and the access stratum message comprises the first CN ID and / or the first CN type ID identifying the first CN type, the broadcast system information contains radio resource configuration information that is common for all UEs, and barring information applied to a unified access control, the broadcast system information pertains to at least a first cell of the RAN that is served by the RAN node, the broadcast system information comprises a cell access related information, CARI, information element, IE, that indicates cell access related information for the first cell, and the first CN type indicator is included within the CARI IE.

33. A method (500) performed by a radio access network, RAN, node (104), the method comprising: transmitting (s502) system information, SI (m201), including at least a first core network, CN, type indicator indicating a first CN type.

34. The method of claim 33, wherein the SI pertains to at least a first cell of the RAN that is served by the RAN node, the SI comprises a cell access related information, CARI, information element, IE, that indicates cell access related information for the first cell, the first CN type indicator is included within the CARI IE, the CARI IE comprises public land mobile network, PLMN, identity information, and the PLMN identity information comprises: one or more PLMN identifiers; and the first CN type indicator.

35. The method of claim 33 or 34, wherein the method further comprises receiving from a user equipment, UE (102), an access stratum message comprising a non-access stratum message, the access stratum message further comprises CN selection information, wherein the CN selection information comprises the first CN type identifier or a CN identifier that identifies a CN of the type indicated by the first CN type identifier, and the method further comprises forwarding the NAS message based on the CN selection information.

36. A method (600) core network, CN, node (900) operating in a CN (106, 108) of a particular CN type, the method comprising: transmitting to a radio access network, RAN, node (104) a CN type indicator indicating said particular CN type.

37. The method of claim 36, wherein the method further comprises transmitting a NAS message to a UE registered with the CN node, wherein the NAS message comprises a UE route selection policy, URSP, rule comprising a CN type indicator, thereby enabling the UE to determine, based on the URSP rule, whether a CN type indicated by a CN type indicator transmitted by a node of the RAN is a desired CN type.

38. A computer program (743) comprising instructions (744) which when executed by processing circuitry (702) of a UE (102) causes the UE (102) to perform the method of any one of claims 1-17, or when executed by processing circuitry (802) of a RAN node (104) causes the RAN node(104) to perform the method of any one of claims 18-28, or when executed by processing circuitry (902) of a CN node (900) causes the CN node (900) to perform the method of any one of claims 29-30.

39. A carrier containing the computer program of claim 38, wherein the carrier is one of an electronic signal, an optical signal, a radio signal, and a computer readable storage medium (742, 842, 942).

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