User equipment, access and mobility management function device and method thereof

Abstract

The invention provides user equipment, access and mobility management function equipment and a method for implementing the access and mobility management function equipment. Many commercially deployed devices support more than one SIM card. At present, support for multiple USIMs is handled in an implementation-specific manner without any support from the 3GPP specification. As the complexity of a UE with 5G capability increases and the demand on the market for multiple USIM devices increases, it is important to consider system enhancements that will allow more efficient solutions involving the required support of the UE from the 5G core and 5G-RAN.

Description

[0001] This application is a divisional application of the Chinese invention patent application with the application date of May 1, 2020, application number 202080048614.0, and invention name “System and method for dual SIM UE operation in 5G network”. Technical Field

[0002] The present invention relates to communication systems. In particular, but not exclusively, the present invention relates to wireless communication systems and apparatus operating in accordance with the Third Generation Partnership Project (3GPP) standards or equivalents or derivatives thereof. In particular, but not exclusively, the present invention relates to multi-SIM user equipment (UE) in so-called "5G" (or "next generation") systems. Background Art

[0003] Many commercially deployed devices support more than one SIM card (typically two SIMs). Currently, support for multiple USIMs is handled in an implementation-specific manner without any support from the 3GPP specification and the 5G Core and 5G RAN. As the complexity of 5G-capable UEs increases and the demand for multiple USIM devices increases in the market, it becomes important to consider solutions and system enhancements that will allow for more efficient solutions involving the required support from the 5G Core and 5G-RAN to the UE, and support various new use cases and applications.

[0004] With respect to devices with multi-SIM capabilities, at least the following issues have been identified:

[0005] 1.5G-RAN and the core network (e.g., the Access and Mobility Management Function (AMF) in the core network) are unaware of the UE's multi-SIM capabilities (e.g., two / more SIMs in the same UE) and the UE's radio capabilities (e.g., the number of supported transceivers). This leads to a problem, such as:

[0006] - A Multi-SIM UE may establish a connection and access to a (R)AN that does not support and provide features required by UEs with more than one SIM. Therefore, any subsequent requests from the UE for a particular service are rejected or silently dropped.

[0007] - A Multi-SIM UE may register with an AMF (and other core network entities) that do not support and provide the features required for Multi-SIM scenarios. As a result, any subsequent requests from the UE for specific services are rejected or silently dropped.

[0008] 2. Currently, the UE is unaware whether certain (R)AN and core network function instances (e.g. AMF) support the functions and services requested and required by its multi-SIM use case specific requirements. Summary of the invention

[0009] Problem that the invention aims to solve

[0010] Therefore, the present invention seeks to provide improved methods and related apparatus relating to multi-SIM capable UEs, for example by at least partially solving or at least alleviating one or more of the above problems.

[0011] Solutions for solving problems

[0012] In one aspect, the present invention provides a method performed by a user equipment, i.e., UE, wherein the UE comprises multiple subscriber identity modules, i.e., SIMs, the method comprising: sending information indicating the multi-SIM capability of the UE to a node of a radio access network, i.e., RAN, in a radio resource control message, i.e., RRC message, for use by the node when selecting an access and mobility management function, i.e., AMF, that supports the multi-SIM capability for the UE.

[0013] In one aspect, the present invention provides a method performed by a node of a radio access network, i.e., a RAN, the method comprising: receiving information indicating a multi-SIM capability of a user equipment, i.e., a UE, including multiple subscriber identity modules, i.e., SIMs, in a radio resource control message, i.e., an RRC message; and selecting an access and mobility management function, i.e., an AMF, for the UE that supports the multi-SIM capability.

[0014] In one aspect, the present invention provides a method performed by a user equipment, i.e., a UE, wherein the UE comprises multiple subscriber identity modules, i.e., SIMs, the method comprising: sending information indicating the multi-SIM capability of the UE to an access and mobility management function, i.e., an AMF, in a non-access stratum message, i.e., a NAS message, for use by the AMF in verifying whether the UE has a subscription for multiple SIMs.

[0015] In one aspect, the present invention provides a method performed by an access and mobility management function, i.e., an AMF, the method comprising: receiving information indicating the multi-SIM capability of a user equipment, i.e., a UE, including multiple subscriber identity modules, i.e., SIMs, in a non-access stratum message, i.e., a NAS message; and verifying whether the UE has a subscription for multiple SIMs.

[0016] In one aspect, the present invention provides a user equipment (UE), comprising: a controller, a transceiver and multiple subscriber identity modules (SIMs); wherein the controller is configured to: control the transceiver to send information indicating the multi-SIM capability of the UE to a node of a radio access network (RAN) in a radio resource control message (RRC message), for use by the node when selecting an access and mobility management function (AMF) supporting the multi-SIM capability for the UE.

[0017] On the other hand, the present invention provides a user equipment (UE), comprising: multiple subscriber identity modules (SIMs); and a sending component for sending information indicating the multi-SIM capability of the UE to a node of a radio access network (RAN) in a radio resource control message (RRC message), for use by the node when selecting an access and mobility management function (AMF) supporting the multi-SIM capability for the UE.

[0018] In one aspect, the present invention provides a node of a radio access network (RAN), the node comprising: a controller and a transceiver, wherein the controller is configured to: control the transceiver to receive information indicating the multi-SIM capability of a user equipment (UE) including multiple subscriber identity modules (SIMs) in a radio resource control message (RRC message); and select an access and mobility management function (AMF) that supports the multi-SIM capability for the UE.

[0019] On the other hand, the present invention provides a node of a radio access network (RAN), the node comprising: a receiving component for receiving information indicating the multi-SIM capability of a user equipment (UE) including multiple subscriber identity modules (SIMs) in a radio resource control message (RRC message); and a selecting component for selecting an access and mobility management function (AMF) supporting the multi-SIM capability for the UE.

[0020] On the one hand, the present invention provides a user equipment (UE), comprising: a controller, a transceiver and multiple subscriber identity modules (SIMs); wherein the controller is configured to: control the transceiver to send information indicating the multi-SIM capability of the UE to an access and mobility management function (AMF) in a non-access layer message (NAS message), for use by the AMF when verifying whether the UE has a subscription for multiple SIMs.

[0021] On the other hand, the present invention provides a user equipment, i.e., UE, comprising: multiple subscriber identity modules, i.e., SIMs; and a sending component for sending information indicating the multi-SIM capability of the UE to an access and mobility management function, i.e., AMF, in a non-access stratum message, i.e., NAS message, for use by the AMF in verifying whether the UE has a subscription for multiple SIMs.

[0022] In one aspect, the present invention provides an access and mobility management function (AMF), comprising: a controller and a transceiver, wherein the controller is configured to: control the transceiver to receive information indicating the multi-SIM capability of a user equipment (UE) including multiple subscriber identity modules (SIMs) in a non-access stratum message (NAS message); and verify whether the UE has a subscription for multiple SIMs.

[0023] On the other hand, the present invention provides an access and mobility management function, i.e., AMF, comprising: a receiving component for receiving information indicating the multi-SIM capability of a user equipment, i.e., UE, including multiple subscriber identity modules, i.e., SIMs, in a non-access stratum message, i.e., NAS message; and a verification component for verifying whether the UE has a subscription for multiple SIMs.

[0024] Aspects of the present invention extend to corresponding systems and computer program products such as computer-readable storage media storing instructions, which are capable of operating to program a programmable processor to perform the methods described in the aspects and possibilities as set out above or recorded in the claims, and / or to program a suitably adapted computer to provide an apparatus as recorded in any one of the claims.

[0025] Each feature disclosed in this specification (which term includes the claims) and / or shown in the drawings may be incorporated into the present invention independently of (or in combination with) any other disclosed and / or illustrated feature. In particular, but not limitingly, features according to any claim dependent on a particular independent claim may be introduced into that independent claim in any combination or alone.

[0026] Embodiments of the present invention will now be described by way of example with reference to the accompanying drawings, in which: BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 schematically illustrates a general mobile (cellular or wireless) telecommunication system to which embodiments of the present invention may be applied;

[0028] Figure 2 is formed Figure 1 A schematic block diagram of a mobile device (user equipment) that is part of the system shown;

[0029] Figure 3 is formed Figure 1 A schematic block diagram of a base station device as part of the system shown;

[0030] Figure 4 is formed Figure 1 A schematic block diagram of a core network node (or OAM node / application function) that is part of the system shown;

[0031] Figure 5 Schematically illustrates an enhanced UE registration procedure to support multi-SIM UEs when the SIMs are registered to the same AMF;

[0032] Figure 6Schematically illustrates a process to support multi-SIM UEs where the SIMs are registered to different AMFs;

[0033] Figure 7 Schematically illustrates a typical N2 setup process;

[0034] Figure 8 A typical RAN configuration update process is schematically shown;

[0035] Fig. 9 Schematically illustrates a typical registration procedure to support multi-SIM UEs in the case where both UE-SIM#1 and UE-SIM#2 are registered to the same AMF;

[0036] Fig.10 schematically illustrates a typical registration procedure for supporting multi-SIM UEs in the case where UE-SIM#1 and UE-SIM#2 are registered to different AMFs; and

[0037] Fig.11 A typical capability update procedure between a multi-SIM UE, (R)AN and AMF is schematically shown. DETAILED DESCRIPTION

[0038] Overview

[0039] Figure 1 There is schematically shown a mobile (cellular or wireless) telecommunication system 1 to which the above embodiments may be applied.

[0040] In this network, users of mobile devices 3 (UE) can communicate with each other and other users via corresponding base stations 5 and core network 7 using appropriate 3GPP radio access technologies (RATs) (e.g., E-UTRA and / or 5G RAT). It will be appreciated that a plurality of base stations 5 form a (radio) access network or (R)AN. As will be appreciated by those skilled in the art, although not shown for purposes of illustration, Figure 1 One mobile device 3 and one base station 5 are shown in FIG. 5 , but the system will typically include other base stations and mobile devices (UEs) when implemented.

[0041] Each base station 5 (or "RAN node") controls one or more associated cells (directly or via other nodes such as home base stations, repeaters, remote radio heads, distributed units, and / or the like). Base stations 5 that support E-UTRA / 4G protocols may be referred to as "eNBs," and base stations 5 that support next generation / 5G protocols may be referred to as "gNBs." It should be understood that some base stations 5 may be configured to support both 4G and 5G and / or any other 3GPP or non-3GPP communication protocols.

[0042] The mobile device 3 and its serving base station 5 are connected via a suitable air interface, such as a so-called "Uu" interface, etc. Neighboring base stations 5 are connected to each other via suitable base station-to-base station interfaces, such as so-called "X2" interfaces, "Xn" interfaces, and / or the like. The base stations 5 are also connected to core network nodes via suitable interfaces, such as so-called "S1", "N2" and "N3" interfaces, etc.

[0043] The core network 7 typically includes logical nodes (or "functions") for supporting communications in the telecommunications system 1. Typically, for example, the core network 7 of a "next generation" / 5G system will include a control plane function (CPF) and a user plane function (UPF), etc. For example, it should be understood that the core network 7 may include: one or more access and mobility management functions (AMF) 11; one or more unified data management (UDM) nodes 12; and a network repository function (NRF) 12, etc.

[0044] A connection to an external IP network 20 such as the Internet is also provided from the core network 7 .

[0045] Beneficially, the components of the system 1 are configured to provide improved support for UEs 3 capable of operating with more than one SIM card.

[0046] In the described example, the UE 3 beneficially provides a multi-SIM capability indicator (and / or UE radio capabilities) to the core network functionality.

[0047] This multi-SIM capability indication of the UE 3 may be provided to the RAN node 5 (base station) in a radio resource control (RRC) message. Based on the multi-SIM capability indication of the UE 3, the RAN node 5 may select an AMF that supports multi-SIM (if available). To facilitate this selection, the AMF 10 may indicate its multi-SIM support capability to the RAN node 5 during the NG setup procedure or during the NG-RAN configuration update procedure. If the multi-SIM support capability is not supported, the RAN node 5 may reject the RRC message with a message including an appropriate rejection reason sent to the UE 3. If rejected, the UE 3 may return to the same RAN 5 node as the UE 3 with single SIM capability (i.e., no multi-SIM capability indication is provided).

[0048] The multi-SIM capability indication of UE 3 may be provided in a non-access stratum (NAS) message sent to AMF 10 to attempt to register at AMF 10. RAN 5 may forward the NAS message to AMF 10, and based on the multi-SIM indication of UE 3, AMF 10 may verify the UE subscription for multi-SIM support using UDM 11. If the subscription is supported, AMF 10 may confirm the registration of multi-SIM UE 3. If the subscription is not supported, AMF 10 may reject the registration using a rejection reason. Where appropriate, AMF 10 may reroute UE 3 to an AMF 10 that supports multi-SIM.

[0049] User Equipment (UE)

[0050] Figure 2 It is shown Figure 1 3 is a block diagram of the main components of a UE (mobile device 3). As shown, the UE includes a transceiver circuit 31 that is operable to send signals to and receive signals from connected (one or more) nodes via one or more antennas 33. Figure 2 39, but the UE will of course have all the common functions of a conventional mobile device (such as a user interface 35, etc.), and the functions may be provided by any one or any combination of hardware, software and firmware as appropriate. The controller 37 controls the operation of the UE according to the software stored in the memory 39. For example, the software may be pre-installed in the memory 39 and / or may be downloaded via the telecommunications network 1 or from a removable data storage device (RMD). The software includes an operating system 41 and a communication control module 43, etc. The communication control module 43 is responsible for processing (generating / sending / receiving) signaling messages and uplink / downlink data packets between the UE 3 and other nodes (including (R)AN nodes 5, core network nodes and application functions). Such signaling includes appropriately formatted requests and responses related to the multi-SIM capabilities of the UE and related processes.

[0051] although Figure 2 4. The communication control module 43 is not shown in the figure, but the communication control module 43 will generally include at least an RRC submodule and a NAS submodule. The RRC submodule is operable to generate, send and receive signaling messages formatted according to the RRC standard. For example, such messages are exchanged between the mobile device 3 and its serving base station 5. The NAS submodule is operable to generate, send and receive signaling messages formatted according to the NAS standard. For example, such NAS messages are exchanged between the mobile device 3 and the AMF 10 (via the serving base station 5, using the RRC submodule).

[0052] The term "UE" generally refers to a mobile phone, which includes at least the following components:

[0053] - Mobile Equipment (ME): ME is a "mobile phone" as a hardware device. It includes at least one processor (controller), a memory unit, an antenna, a transceiver unit, a user interface (such as a screen, buttons, cable socket), a battery unit, etc., as described above with reference to Figure 2 described.

[0054] - Subscriber Identity Module (SIM) or Universal Subscriber Identity Module (USIM): SIM or USIM is an application running in the UICC card. The UICC card is a small integrated circuit that includes a related processor (controller), a communication module, a memory unit, and an interface unit to communicate with the ME part as UE3. UICC is also called a "smart card". The processor controls the operation of the USIM according to the software stored in the memory. The USIM software includes an operating system (OS) and a communication control module, etc.

[0055] The term "SIM" generally refers to the application in the UICC card used in the 2G GSM mobile system. The term "USIM" generally refers to the application in the UICC card used in the 3G (UMTS), 4G (LTE) and 5G systems. In addition, "eSIM" is a SIM function embedded in the ME 30 itself, rather than provided using a physical (removable) UICC card. In most technical contexts, these terms are interchangeable and the term "SIM" is more general. From the perspective of the present invention, the terms "SIM", "USIM" and "eSIM" are used interchangeably. SIM and USIM applications and eSIM contain credentials such as long-term identifiers (IMSI in 3GPP) and long-term keys.

[0056] In this disclosure, "ME", "mobile device" or simply "device" is used to refer to the same entity, i.e. a mobile handset generally used for any generation of technology. In addition, "SIM" or "USIM" is used in this disclosure, depending on the context. However, they generally refer to applications that reside in the UICC.

[0057] The UE may be a multi-SIM device. Typically, a mobile device with multi-SIM capabilities is equipped with two SIM card slots, so it is also commonly referred to as a "dual SIM phone". In another UE implementation, the mobile device is equipped with one SIM card slot, and the other SIM functionality is embedded in hardware ("eSIM"). The mobile device may have a single IMEI for each SIM, or a single IMEI common to all SIMs in the mobile device. An example of having a single IMEI common to all SIMs is when a single UICC card contains multiple USIM applications.

[0058] Depending on the hardware implementation, a multi-SIM device / UE may be equipped with one or more than one transceiver circuit 31. When present, such multiple transceiver circuits 31 enable simultaneous connections using multiple SIMs.

[0059] (R)AN Node

[0060] Figure 3 It is shown Figure 1 1 is a block diagram of the main components of a typical (R)AN node 5 (base station) shown in FIG. As shown, the (R)AN node 5 includes a transceiver circuit 51, which is operable to send and receive signals to and from the connected (one or more) UE 3 via one or more antennas 53, and to send and receive signals to and from other network nodes via a network interface 55 (directly or indirectly). The network interface 55 typically includes an appropriate base station-base station interface (such as X2 / Xn, etc.) and an appropriate base station-core network interface (such as S1 / N2 / N3, etc.). The controller 57 controls the operation of the (R)AN node 5 according to the software stored in the memory 59. For example, the software can be pre-installed in the memory 59 and / or can be downloaded via the telecommunications network 1 or from a removable data storage device (RMD). The software includes an operating system 61 and a communication control module 63, etc. The communication control module 63 is responsible for processing (generating / sending / receiving) signaling between the (R)AN node 5 and other nodes (such as UE 3 and core network node / AF 12, etc.). Such signaling includes appropriately formatted requests and responses relating to the UE's multi-SIM capabilities and related procedures.

[0061] Core network nodes

[0062] Figure 4 is a block diagram showing the main components of a generic core network node (or function), which may be configured to implement Figure 1 and Figures 5 to 1110, and any core network node or function (e.g., AMF 10, UDM 11, and NRF 12) shown in the figure. As shown, the core network node includes a transceiver circuit 71, which is operable to send and receive signals to other nodes (including UE 3 and (R) AN node 5) via a network interface 75. A controller 77 controls the operation of the core network node according to software stored in a memory 79. For example, the software can be pre-installed in the memory 79 and / or can be downloaded via the telecommunications network 1 or from a removable data storage device (RMD). The software includes an operating system 81 and at least one communication control module 83, etc. The communication control module 83 is responsible for processing (generating / sending / receiving) signaling between the core network node and other nodes (such as UE 3, (R) AN node 5, UDM 11, NRF 12, and other core network nodes, etc.). Such signaling includes appropriately formatted requests and responses related to the multi-SIM capabilities of the UE and related processes.

[0063] Detailed Description

[0064] The following description is particularly applicable to UEs with more than one SIM and to different scenarios and use cases, including but not limited to:

[0065] - Dual SIM Dual Standby (DSDS) devices (reference: GSMA TS.37: Requirements for Multi SIM devices, ver 5.0);

[0066] - A UE with a single transmitter and a single receiver;

[0067] -UE with a single transmitter and multiple receivers;

[0068] - SIMs belonging to the same MNO (e.g. one for a personal subscription and another for a business subscription, both used on the same device).

[0069] Embodiment 1:

[0070] The first embodiment proposes a method and system to solve at least one of the problems described above specifically for UE 3 having more than one SIM / USIM 45. This embodiment proposes a method and system as described below. The proposed method and system enable a multi-SIM UE 3 to send a notification including an indication of the multi-SIM capability that the UE 3 has. The notification may include an indication of at least one (one or more) transceivers supported by the UE 3. The description of this embodiment also includes:

[0071] -like Figure 5 and 6In these processes, the RAN function can select and / or relocate to an AMF 10 that can provide the service(s) required by the multi-SIM UE 3. The selected or relocated AMF 10 may be the most suitable AMF to provide the service(s).

[0072] - In step 2a, based on appropriate parameters (e.g. multi-SIM capability indicator), the RAN 5 (base station) selects an AMF 10 that can provide the service(s) required by the UE 3 with two / more SIMs.

[0073] - The RAN 5 may also inform the UE 3 of the lack of support for the requested capabilities. The UE 3 may then access another RAN 5 (e.g. in case of overlapping coverage areas), or the UE 3 may access the same RAN 5 without any additional information about the UE's multi-SIM capabilities (effectively, in the absence of such a multi-SIM capability indicator, the UE 3 appears to the network as a single SIM UE 3), and the UE 3 may then repeat the registration process for each SIM 45.

[0074] - Additional parameters are sent via RRC messages (e.g., multi-SIM capabilities, single and / or multiple receivers and / or transceivers) and NAS messages (e.g., multi-SIM capabilities, single and / or multiple receivers and / or transceivers). The additional parameters (e.g., single / multiple receivers and transmitters) help the 5G Core Network to determine whether UE-specific paging optimization or coordination is required, taking into account the capabilities of the UE 3. For example, the AMF can determine whether the UE 3 can receive two SIM signaling simultaneously. If the UE 3 can receive signaling to different SIMs 45 simultaneously, the UE 3 can behave as usual and no additional support is required.

[0075] -UDM 11 stores "multi-SIM" related information corresponding to the subscription profile of the UE (e.g., information indicating whether multi-SIM operation is allowed or prohibited), and requires AMF 10 to obtain subscription and policy information from UDM 11 and Policy Control Function (PCF), respectively.

[0076] Figure 5 An enhanced UE registration procedure to support multi-SIM UE 3 when the SIM 45 is registered to the same AMF 10 is schematically shown.

[0077] The following explains Figure 5 The registration process of SIM#1 and USIM#2 (or SIM#2) is independent. In the case of the same PLMN, the AMF selection and relocation mechanism results in the selection of the same AMF 10 for SIM#1 and SIM#2.

[0078] Step 0: RRC connection established

[0079] Step 1: UE 3 sends an RRC message including new parameter(s) to NG-RAN 5 to indicate the multi-SIM capability of the UE. UE 3 may additionally include its radio capabilities as single / multiple receivers (Rx) and transmitters (Tx). UE 3 may send an NAS message including new parameter(s) to NG-RAN.

[0080] Step 2: Based on the received AN parameter(s) including the request for "multi-SIM" capability and additional receiver / transceiver capabilities, the RAN determines whether the RAN supports the requested functionality. In the case that the RAN does not support the requested functionality, the RAN 5 may reply to the UE 3 with a cause value of lack of support. The UE 3 may then join another RAN 5 (e.g. in case of overlapping coverage areas), or the UE may access the same RAN 5 (e.g. using a single SIM UE registration procedure) without any additional information about the UE's multi-SIM capabilities. To assist in this process, the RAN 5 may also periodically broadcast and provide its (multi-SIM) capability information, which may be monitored by the UE 3 to allow the UE 3 to be aware of the multi-SIM capability before sending its request to the RAN 5 (as in step 1 above).

[0081] Step 2a: Based on the parameter(s) received in step 2, the RAN 5 selects an AMF 10 that supports the functionality required by the UE 3 with multi-SIM capability, instead of selecting a default AMF 10 and / or forwarding to the AMF 10 based on the received NSSAI information, for example. In order to determine the most suitable AMF 10, the RAN 5 may perform one or more of the following steps:

[0082] i. the RAN 5 may have a list including at least one (pre-)configured AMF(s), and the RAN 5 may select a specific AMF 10 for the purpose (e.g. an AMF 10 that supports the requested functionality);

[0083] ii. RAN 5 may select the same AMF 10 for SIM#1 and SIM#2. As part of a separate process (e.g., the separate process provided in Embodiment 2), RAN 5 may learn the AMF 10 to which SIM#1 (and SIM#2 belonging to the same UE 3) is registered;

[0084] iii. RAN 5 is based on the N2 setting process described in Example 2 (eg Figure 7The information obtained in (as shown) is used to select AMF 10 to find AMF;

[0085] iv.RAN 5 based on the NG-RAN configuration update process as described in Example 2 (eg Figure 8 The AMF 10 is selected based on the information obtained in the AMF 10 (as shown) to find (one or more) AMF 10. The found (one or more) AMF 10 may be the most suitable (one or more) AMF 10.

[0086] Step 3: RAN 5 forwards the received NAS message (e.g., N2 Setup Request message) to the AMF 10 selected in the above step 2a.

[0087] Step 4: The AMF 10 follows the procedure with the UDM 11 to retrieve and confirm the subscription information of the Multi-SIM UE 3. Nudm_SDM_Get service request / reply is exchanged with additional information related to the Multi-SIM capability and subscription. Figure 5 One UDM 11 and one step 4 are shown, but step 4 may be repeated as many times as the number of SIMs 45 being processed. The AMF 10 may access another UDM 11, since the respective relevant UDMs 11 of the respective SIMs 45 may be different.

[0088] The remaining registration procedures are performed before step 5 as described in 3GPP TS 23.502 v16.0.0 [3].

[0089] Step n: AMF 10 determines whether the network supports multi-SIM function.

[0090] Step n+1: AMF 10 notifies NG-RAN 5 of the successful registration process. However, in the case of lack of multi-SIM functionality support (e.g., if the UE is not subscribed (subscription failed in the previous step with UDM 11), AMF 10 does not support and / or VPLMN does not support multi-SIM), AMF 10 notifies NG-RAN 5 of the lack of requested capability support using a new cause value (multi-SIM related cause value). The cause value corresponds to one / more of the following: not subscribed, not supported by the core network, not supported by VPLMN. For example, the cause value may be included in a registration accept message or an N2 setup response message.

[0091] Step n+2: RAN 5 notifies of the successful registration process. However, in the absence of multi-SIM functionality support (if indicated in step 5 above), the NG-RAN 5 sends the cause value to the UE 3. The UE 3 may then attempt to register without any additional information about multi-SIM (e.g. as with a normal single SIM registration). For example, the cause value may be included in the UE Registration Accept message.

[0092] Figure 6 The process to support multi-SIM UE 3 where the SIM 45 is registered to different AMFs 10 is schematically shown.

[0093] Figure 6 The process shown is similar to Figure 5 The process shown is the same, however, the difference is that Figure 6 The process shown allows and takes into account the scenario where different SIM 45 are registered to different AMF 10. The process as described above also applies to Figure 6 In this case, the UE registration procedures for SIM#1 and SIM#2 are independent, but each has a multi-SIM capability parameter (and corresponding required behavior). In this case, the NG-RAN 5 and / or AMF 10 coordinates and ensures that both SIMs 45 are registered to the same AMF 10 (e.g. Figure 6 1 or AMF2 10-2 in the UE 3 and / or UDM 11) without relocating the AMF of SIM#1 and / or SIM#2 to the common AMF 10. In addition, SIM#1 and SIM#2 may be registered to different AMFs 10 due to a lack of sufficient information available to the AMF 10 (e.g., in the absence of additional information and required information provided by the UE 3 and / or UDM 11). This also avoids the NG-RAN having to know the AMF with which SIM#1 is registered, and vice versa. SIM#1 and SIM#2 belong to the same PLMN.

[0094] Embodiment 2:

[0095] The second embodiment proposes a method and system to solve one or more of the problems described above specifically for UE 3 with more than one USIM 45. This embodiment proposes a method and system as described below:

[0096] -NG Connection Setup, whereby the NG-RAN 5 indicates its support (or lack of support) for multi-SIM capabilities to the AMF 10 in the N2 Setup Request message.

[0097] -NG Connection Setup Response message from the AMF 10 to indicate its support (or lack of support) for multi-SIM capabilities.

[0098] Figure 7 schematically illustrates a typical N2 setup process according to the second embodiment, and Figure 8 A typical RAN configuration update process of the second embodiment is schematically illustrated.

[0099] In this example, the RAN configuration update process includes:

[0100] - RAN Configuration Update Request message, whereby the NG-RAN 5 (base station) indicates its support (or lack of support) for multi-SIM capabilities; and

[0101] -RAN Configuration Update Response message from the AMF 10 to indicate its support (or lack of support) for multi-SIM capabilities.

[0102] Embodiment 3:

[0103] Fig. 9 A typical registration procedure to support a multi-SIM UE 3 in the case where both UE-SIM#1 and UE-SIM#2 are registered to the same AMF 10 is schematically illustrated.

[0104] This embodiment allows a UE 3 with two / more SIMs 45 to inform the network of its multi-SIM capability and register with the appropriate network function (NF). The method comprises:

[0105] - Enhanced registration procedure whereby a UE 3 with multi-SIM capability provides a new parameter (herein referred to as multi-SIM capability) in the UE Registration Request message (to indicate support for services of two / more SIMs 45 in the same UE 3). In addition, the UE 3 may also include information on whether it supports a single transceiver or multiple receivers / transmitters.

[0106] - This enables AMF selection functionality and AMF relocation and / or other core network functions / entity selection suitable for providing the services required by Multi-SIM UE 3.

[0107] - Enables the UDM 11 to store the "Multi-SIM" capability corresponding to the subscription profile of the UE.

[0108] - This also allows the AMF 10 to obtain subscription and policy information specific to multi-SIM support from the UDM 11 and PCF respectively.

[0109] - In step 2a, the RAN 5 forwards to the default / configured AMF A 10-A, followed by AMF relocation (e.g., newly proposed steps 2b, 2c, and 2d).

[0110] - In case the multi-SIM capability requested by the UE 3 is not supported, the AMF 10 informs the UE 3 of the possible reasons (e.g. due to lack of subscription, policy and / or unsupported features).

[0111] The following instructions Fig. 9 The registration process for SIM#1 and SIM#2 is independent. In the case of two SIMs with the same PLMN, the AMF selection and relocation mechanism results in the selection of the same AMF 10 (AMF B 10-B in this example) for both SIM#1 and SIM#2.

[0112] Step 1: UE 3 requests registration of SIM#2. Compared with the registration procedure in 3GPP TS23.502 V16.0.0, here UE 3 also includes information indicating its multi-SIM capability, and additionally may also include information indicating the number of supported transceivers and receivers.

[0113] Step 2: In step 2a, the RAN 5 forwards the received NAS message to the default or configured AMF 10 (AMF A 10-A in this example). However, based on the received UE capability information, the AMF 10 decides to perform "AMF relocation" so that the UE 3 is registered with an AMF 10 that provides the features required by the UE 3 with two / more SIMs 45. The AMF relocation is shown in steps 2b and 2c:

[0114] Step 2b: AMF A 10-A to UDM 11: Nudm_SDM_Get (Subscription Permanent Identifier (SUPI), Multi-SIM Subscription Data). AMF A 10-A requests the UE's multi-SIM subscription data from UDM 11 by calling Nudm_SDM_Get service operation. In other examples, UDM 11 may obtain this information from a unified data repository (UDR). UDM 11 replies to AMF A 10-A.

[0115] Step 2c: AMF A 10-A to NRF 12: Nnrf_NFDiscovery_Request (NF type, AMF set). If AMF A 10-A does not locally store the AMF address that supports the requested multi-SIM capability, AMF A 10-A calls the Nnrf_NFDiscovery_Request service operation from NRF 12 to find a suitable target AMF 10 with the NF capabilities required to serve UE 3. The NF type is set to AMF. The AMF set is included in the Nnrf_NFDiscovery_Request. NRF 12 replies with a list of potential AMF 10 (a list of at least one AMF). NRF 12 can also provide details of the services provided by the candidate (one or more) AMF10.

[0116] -Therefore, the NRF 12 maintains this additional information corresponding to the AMF 10 (e.g., UE's multi-SIM capability related information).

[0117] Step 2d: If AMF A 10-A decides to forward the NAS message directly to AMF B 10-B based on local policy and subscription information, AMF A 10-A calls Namf_Communication_N1MessageNotify to AMF B 10-B, carrying the rerouted NAS message.

[0118] Fig.10 A typical registration process to support multi-SIM UE 3 where the SIMs are registered to different AMFs 10 is schematically shown.

[0119] Fig.10 The process shown is similar to Fig. 9 The process is the same as in Fig.10 The process shown allows and takes into account the scenario where different SIM 45 are registered to different AMF 10. The process described above also applies to Fig.10 . The UE registration procedures for SIM#1 and SIM#2 are independent. SIM#1 and SIM#2 belong to the same PLMN. The AMF selection is based on steps 2b, 2c and 2d. For example, the RAN 5 is not aware of the default or configured AMF 10 (in Fig.10 Steps 2b, 2c and 2d are required to ensure that the AMF is relocated and an AMF (in FIG. 4 ) that provides the features required by the UE 3 with two / more than two SIMs 45 is selected. Fig.10 1 and 2 are shown as AMF 110-1 and AMF 210-2 for SIM#1 and SIM#2 respectively).

[0120] Embodiment 4:

[0121] To support the 5G Core Network 7 as well as multi-SIM specific features of multi-SIM UEs 3, the following parameters are added to the "UE Capability ID" and "UE Radio Capability ID" information elements:

[0122] -UE Radio Capability ID: number of receiver(s) and transmitter(s)

[0123] -UE Capability ID: Multi-SIM indicator (to indicate that the UE 3 has more than one associated SIM 45)

[0124] Therefore, in order to be consistent with the ongoing research on the optimization of UE radio capability signaling or radio capability signaling optimization (RACS) defined in 3GPP Technical Report (TR) 23.743v2.0.0, the feature of "dictionary for translating these IDs" needs to be updated based on this proposal. Specifically, the corresponding message is enhanced to include at least one of the multi-SIM specific parameters: multi-SIM indicator and the number of Tx / Rx.

[0125] These corresponding messages are in:

[0126] I.UE Capability Management Function (UCMF) and AMF

[0127] II.AMF and Application Function (AF), directly or via Network Exposure Function (NEF)

[0128] III. AF and UCMF

[0129] Exchange between.

[0130] An example of the update process is in Fig.11 If the AMF 10 has not provided the UE radio capabilities as part of the establishment of the UE context in the RAN 5, the RAN 5 retrieves the UE radio capabilities over the radio interface and informs the AMF 10 using the "N2 UE Capability Information Indication" message.

[0131] Step 1: In case the RAN 5 has not received the UE radio capabilities and UE capabilities, for example via a different procedure, the RAN 5 requests the UE radio capabilities and UE capabilities.

[0132] Step 2: UE 3 replies with its radio capabilities and UE capabilities.

[0133] Step 3: RAN 5 provides the received capabilities to AMF 10.

[0134] Summarize

[0135] Advantageously, the above aspects include but are not limited to one or more of the following functions:

[0136] 1) The UE provides the (5G) core network with a multi-SIM capability indicator and / or UE radio capabilities:

[0137] a. This enables the AMF selection function and AMF relocation and / or other core network functions / entities to select the appropriate NF for providing the services required by multi-SIM UEs

[0138] 2) The UE provides the multi-SIM capability indicator and / or UE radio capabilities to the 5G RAN:

[0139] a. This enables the RAN function to select an AMF and / or relocate the AMF that is most suitable to provide the services required by the multi-SIM UE. For example, in embodiment 1, in the newly proposed feature in step 2, after receiving these parameters, the RAN forwards the request to the appropriate AMF (rather than the default AMF). In order to determine the most suitable / appropriate AMF, there are multiple options:

[0140] i. The RAN may have a list of at least the (pre-)configured AMFs for this purpose;

[0141] ii. RAN follows the process described in Example 2 (eg Figure 7 As shown), to find the most suitable AMF;

[0142] iii. RAN follows the process described in Example 2 (eg Figure 8 to find the most suitable AMF.

[0143] 3) The core network and RAN provide the UE with an appropriate cause value. The cause value indicates whether the requested network entity supports the features requested by the UE with two / more SIMs to allow the UE to register with the appropriate RAN and AMF and / or request the required services.

[0144] a. Example: As explained in Embodiment 1, the RAN notifies the UE of the lack of requested capability support. The UE can then join another RAN (eg, in case of overlapping coverage areas) or fall back to normal behavior, etc.

[0145] 4) NRF maintains a list of (one or more) AMFs that support multi-SIM capabilities and corresponding functions. Based on this information, NRF can also provide information to AMF to assist AMF relocation.

[0146] 5) Additional parameters are proposed to be included in "UE Capability ID" and "UE Radio Capability ID".

[0147] To provide these functions, the above aspects describe a typical method including (at least some of) the following steps:

[0148] Example 1: RRC-based process

[0149] - The UE includes its capability information in the RRC message, such as "Multi-SIM Capability"

[0150] - Additionally, the UE includes information about its transceiver(s) (eg, single Tx / Rx or multiple Rx and Tx).

[0151] - RAN functions for selecting (and / or relocating) an AMF suitable for providing the services required by a multi-SIM UE, such as Figure 5 and 6 As in step 2a in .

[0152] -RAN may also inform the UE of the lack of support for the requested capability. The UE may then join another RAN (e.g. in case of overlapping coverage areas) or fall back to normal behavior. To achieve this, the RAN may regularly broadcast and / or provide its (multi-SIM) capability information, which may be monitored by the UE to know before sending a request to the RAN.

[0153] Example 2: N2 connection setup and RAN configuration update

[0154] -RAN and AMF exchange multi-SIM related capabilities.

[0155] Example 3: Registration process

[0156] - The UE includes its multi-SIM capability request and the additional supported receivers and transmitters in the Registration Request message.

[0157] -AMF performs / initiates AMF relocation upon receiving information from UE, e.g. Fig. 9 and 10 As in steps 2b, 2c and 2d in .

[0158] -NRF maintains a list of AMFs that support multi-SIM capabilities and the corresponding functions. Based on this information, NRF can also provide information to AMF to assist AMF relocation.

[0159] - In case of failure to accept the UE's registration request, the AMF may reply to the UE with appropriate cause information.

[0160] Example 3: RACS process

[0161] - Additional parameters proposed to be included in the "UE Capability ID" information element and the "UE Radio Capability ID" information element.

[0162] -Then update these parameters, such as Fig.11 shown.

[0163] benefit

[0164] The above mentioned multi-SIM capability negotiation ensures registration to the more appropriate RAN and / or core network functionality, for example to ensure requested and optimal behavior. This additionally avoids the possibility of failure after registration if the requested functionality of a UE with more than one SIM is not supported.

[0165] Modifications and Replacements

[0166] Detailed embodiments have been described above. As will be appreciated by those skilled in the art, a variety of modifications and substitutions may be made to the exemplary embodiments described above while still benefiting from the inventions embodied therein. Many of these substitutions and modifications will now be described by way of illustration only.

[0167] In the above description, for ease of understanding, the UE, (R)AN node and core network node are described as having multiple discrete modules (such as communication control modules, etc.). Although these modules may be provided in this way for certain applications, for example, where an existing system has been modified to implement the present invention, in other applications, such as in a system designed from the outset with the features of the present invention in mind, these modules may be built into the entire operating system or code, and therefore these modules may not be discernible as discrete entities. These modules may be implemented in the form of software, hardware, firmware or a combination thereof.

[0168] Each controller may include any suitable form of processing circuitry, including (but not limited to) for example: one or more hardware-implemented computer processors; a microprocessor; a central processing unit (CPU); an arithmetic logic unit (ALU); input / output (IO) circuits; internal memory / cache (program and / or data); processing registers; a communications bus (e.g., a control bus, a data bus, and / or an address bus); direct memory access (DMA) functionality; hardware or software-implemented counters, pointers, and / or timers; and / or the like.

[0169] In the above embodiments, a plurality of software modules are described. As will be appreciated by those skilled in the art, the software modules can be provided in compiled or uncompiled form and can be provided to the UE, (R) AN node and core network node as a signal over a computer network or on a recording medium. In addition, one or more dedicated hardware circuits may be used to perform some or all of the functions performed by the software. However, the use of software modules is preferred because it facilitates updating the UE, (R) AN node and core network node to update their functions.

[0170] The above embodiments may also be applicable to "non-mobile" or generally stationary user equipment.

[0171] The method performed by the UE may further include receiving a message for rejecting the RRC message, where the received message includes a rejection reason.

[0172] The method performed by the UE may also include sending other RRC messages if the RRC message is rejected, wherein the other RRC messages do not have information indicating the multi-SIM capability of the UE for selecting an AMF for the UE.

[0173] The information indicating the multi-SIM capability of the UE may include a "UE Capability ID" information element.

[0174] The method performed by the UE may further include sending (eg, in a "UE Radio Capability ID" information element) information indicating the number of transceivers associated with the plurality of SIMs.

[0175] The method performed by the node of the RAN may also include obtaining information indicating whether the AMF supports multi-SIM capabilities from at least one AMF, and selecting an AMF for the UE based on the obtained information. The information may be obtained by the node of the RAN during an N2 setup procedure or during a RAN configuration update procedure performed with at least one AMF.

[0176] The method performed by the AMF may also include: i) registering the UE with the AMF for multiple SIMs if the UE has a subscription for multiple SIMs; and ii) rejecting the UE's registration with the AMF using an appropriate rejection reason if the UE does not have a subscription for multiple SIMs. In the case where the AMF does not support multiple SIMs, the method performed by the AMF may also include rerouting the UE to a different AMF that supports multiple SIMs.

[0177] The verification performed by the AMF may be based on subscription information associated with the UE obtained from a unified data management (UDM) function or a unified data repository (UDR) function.

[0178] In the case where at least one of the multiple SIMs is registered to a different AMF, the method performed by the AMF may further include performing AMF relocation for at least one of the multiple SIMs to register the multiple SIMs at the same AMF.

[0179] Various other modifications will be apparent to those skilled in the art and will not be described in further detail here.

[0180] List of abbreviations

[0181] 3GPP Third Generation Partnership Project

[0182] AF Application Function

[0183] AMF Access and Mobility Management Function

[0184] API Application Programming Interface

[0185] EPS Evolved Packet System

[0186] GPRS General Packet Radio Service

[0187] GTP-C GPRS Tunneling Protocol

[0188] HOL thread

[0189] HTTPS Hypertext Transfer Protocol Secure

[0190] MNO Mobile Network Operator

[0191] NEF Network Exposure Function

[0192] NF Network Function

[0193] NRF Network Repository Features

[0194] PCF Policy Control Function

[0195] RAN Radio Access Network

[0196] QoS Quality of Service

[0197] QUIC Fast UDP Internet Connection

[0198] REST Representational State Transfer

[0199] SDL Shared Data Layer

[0200] SLA Service Level Agreement

[0201] SMF session management functions

[0202] TCP Transmission Control Protocol

[0203] TLS Transport Layer Security

[0204] TTI Transmit Time Interval

[0205] UDM Unified Data Management

[0206] UDR Unified Data Repository

[0207] UPF User Plane Function

[0208] UE User Equipment

[0209] UICC Universal Integrated Circuit Card

[0210] (U)SIM Universal Subscriber Identity Module

[0211] Reference List

[0212] [1]3GPP TR 21.905: "Vocabulary for 3GPP Specifications".V15.0.0(2018-03)

[0213] [2]3GPP TS23.501: "System Architecture for the 5G System; Stage 2".V16.0.0(2019-03)

[0214] [3]3GPP TS23.502: “Procedures for the 5G System; Stage 2” V16.0.0 (2019-03)

[0215] [4]New SID:Study on system enablers for multi-SIM devices

[0216] http: / / www.3gpp.org / ftp / tsg_sa / TSG_SA / TSGS_82 / Docs / SP-181251.zip

[0217] [5]3GPP SA2 TR 23.743v2.0.0:Study on optimizations of UEradiocapability signaling

Claims

1. A method performed by a user equipment (UE), wherein the UE comprises a plurality of subscriber identity modules (SIMs), the method comprising: Sending a first non-access stratum message, i.e., a first NAS message, to an access and mobility management function device, i.e., an AMF device, wherein the first NAS message includes first information indicating a multi-SIM capability of the UE; and receiving a second NAS message from the AMF device, wherein the second NAS message includes second information including a multi-SIM related value, the multi-SIM related value being based on the first information and a multi-SIM feature supported by the network, The multi-SIM related value is configured to indicate whether the multi-SIM capability of the UE indicated by the first information is also supported by the network.

2. The method according to claim 1, wherein: The first NAS message is a Registration Request message, and the second NAS message is a Registration Accept message.

3. A user equipment (UE), the UE comprising a plurality of subscriber identity modules (SIMs), the UE comprising: A component for sending a first non-access stratum message, i.e., a first NAS message, to an access and mobility management function device, i.e., an AMF device, wherein the first NAS message includes first information indicating a multi-SIM capability of the UE; and means for receiving a second NAS message from the AMF device, wherein the second NAS message comprises second information including a multi-SIM related value, the multi-SIM related value being based on the first information and a multi-SIM feature supported by the network, The multi-SIM related value is configured to indicate whether the multi-SIM capability of the UE indicated by the first information is also supported by the network.

4. The UE according to claim 3, wherein: The first NAS message is a Registration Request message, and the second NAS message is a Registration Accept message.

5. A method performed by an access and mobility management function device, i.e., an AMF device, the method comprising: receiving a first non-access stratum message (a first NAS message) from a user equipment (a UE) comprising a plurality of subscriber identity modules (SIMs), wherein the first NAS message comprises first information indicating a multi-SIM capability of the UE; and sending a second NAS message to the UE, wherein the second NAS message includes second information including a multi-SIM related value, the multi-SIM related value being based on the first information and a multi-SIM feature supported by the network, The multi-SIM related value is configured to indicate whether the multi-SIM capability of the UE indicated by the first information is also supported by the network.

6. The method according to claim 5, further comprising: Based on the multi-SIM feature supported by the network, it is determined whether the multi-SIM capability of the UE indicated by the first information is also supported by the network.

7. The method according to claim 5 or 6, wherein: The first NAS message is a Registration Request message, and the second NAS message is a Registration Accept message.

8. An access and mobility management function device, namely an AMF device, the AMF device comprising: means for receiving a first non-access stratum message, i.e. a first NAS message, from a user equipment, i.e. a UE, comprising a plurality of subscriber identity modules, i.e. SIMs, the first NAS message comprising first information indicating a multi-SIM capability of the UE; as well as means for sending a second NAS message to the UE, wherein the second NAS message comprises second information including a multi-SIM related value, the multi-SIM related value being based on the first information and a multi-SIM feature supported by the network, The multi-SIM related value is configured to indicate whether the multi-SIM capability of the UE indicated by the first information is also supported by the network.

9. The AMF device according to claim 8, further comprising: A means for determining, based on the multi-SIM feature supported by the network, whether the multi-SIM capability of the UE indicated by the first information is also supported by the network.

10. The AMF device according to claim 8 or 9, wherein: The first NAS message is a Registration Request message, and the second NAS message is a Registration Accept message.

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