Apparatus, systems, methods, and computer-readable media for cellular system enhancements supporting multi-SIM user equipments

Abstract

Apparatuses, systems, methods, and computer-readable media are disclosed for cellular system enhancements supporting multi-SIM user equipment. An embodiment discloses an electronic device comprising a receiver configured to receive a first subscriber identity module (SIM); a receiver configured to receive a second SIM; and circuitry configured to receive data from the first SIM; and transmitting to a first public land mobile network (PLMN) a request to register the electronic device with the first PLMN, where the request indicates that the electronic device is a multi-SIM device and the request includes multi-SIM assistance information, and where the multi-SIM assistance information notifies the first PLMN of a preference of the electronic device for multi-SIM operation.

Description

[0001] This application is a divisional application of an invention patent application with an application date of March 24, 2020, application number 202080049624.6, and invention name “Device, system, method and computer-readable medium for cellular system enhancement to support multi-SIM user equipment”.

[0002] CROSS-REFERENCE TO RELATED APPLICATIONS

[0003] This application claims the benefit of U.S. Provisional Application No. 62 / 928,379, filed on October 31, 2019, U.S. Provisional Application No. 62 / 899,322, filed on September 12, 2019, and U.S. Provisional Application No. 62 / 858,747, filed on June 7, 2019, the entire contents of which are incorporated herein by reference. Technical Field

[0004] The present disclosure relates generally to wireless communications, and more particularly to wireless communications systems, devices, methods, and computer-readable media having computer-executable instructions for enhancing cellular systems to support the use of 4G and 5G multiple Subscriber Identity Module (SIM) User Equipment (UE). Background Art

[0005] The "background technology" description provided herein is intended to generally present the context of the present disclosure. To the extent it is described in this background technology section, the work of the inventors currently named and the description of aspects that may not be prior art at the time of filing the application are not explicitly or implicitly admitted as prior art to the present invention.

[0006] To date, multi-SIM UEs are proprietary solutions implemented by device manufacturers without knowledge of the core network and are outside the scope of 3GPP standards. The operation of cellular networks is designed where the behavior of the various entities (UE, RAN and CN) is well defined and known among the various entities. With the different implementations of existing multi-SIM UEs, the different behaviors of the different implementations have a negative impact on the operation of the network and may even degrade its performance. Summary of the invention

[0007] An exemplary embodiment of the present disclosure provides an electronic device, comprising a receiver configured to receive a first subscriber identity module (SIM); a receiver configured to receive a second SIM; and a circuit system configured to receive data from the first SIM; and send a request to a first public land mobile network (PLMN) to register the electronic device to the first PLMN, wherein the request indicates that the electronic device is a multi-SIM device and the request includes multi-SIM assistance information, and wherein the multi-SIM assistance information notifies the first PLMN of the electronic device's preference for multi-SIM operation.

[0008] An exemplary embodiment of the present disclosure provides a method performed by an electronic device, the method comprising: receiving data from a first subscriber identity module (SIM); and sending a request to a first public land mobile network (PLMN) to register the electronic device to the first PLMN, wherein the request indicates that the electronic device is a multi-SIM device and the request includes multi-SIM assistance information, and wherein the multi-SIM assistance information notifies the first PLMN of the device's preference for multi-SIM operation.

[0009] An exemplary embodiment of the present disclosure provides a non-transitory computer-readable medium including computer-executable instructions, which, when executed by an electronic device, causes the electronic device to: receive data from a first subscriber identity module (SIM); and send a request to a first public land mobile network (PLMN) to register the electronic device to the first PLMN, wherein the request indicates that the electronic device is a multi-SIM device and the request includes multi-SIM assistance information, and wherein the multi-SIM assistance information notifies the first PLMN of the device's preference for multi-SIM operation.

[0010] This summary is provided to introduce a series of concepts in a simplified form, which will be further described in the following detailed description. This summary is not intended to identify the key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter. In addition, the claimed subject matter is not limited to address any or all of the limitations pointed out in any part of this disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] The scope of the present disclosure is best understood from the following detailed description of exemplary embodiments when read in conjunction with the accompanying drawings, in which:

[0012] Figure 1A is a system diagram illustrating an example 3GPP architecture;

[0013] Figure 1B is a system diagram showing an example of a radio access network (RAN) architecture and a core network architecture;

[0014] Figure 1C is a system diagram showing an example of a radio access network (RAN) architecture and a core network architecture;

[0015] Figure 1D is a system diagram showing an example of a radio access network (RAN) architecture and a core network architecture;

[0016] Figure 1E is a system diagram illustrating an example 3GPP architecture;

[0017] Figure 1F is a system diagram of an example apparatus or device configured for wireless communication;

[0018] Figure 1G is a system diagram illustrating an example of a computing system for use in a communication network;

[0019] Figure 2 A non-roaming 5G system architecture according to an exemplary embodiment is shown;

[0020] Figure 3 A roaming 5G system architecture according to an exemplary embodiment is shown;

[0021] Figure 4 A roaming 5G system architecture according to an exemplary embodiment is shown;

[0022] FIG5 illustrates a 5G universal registration process according to an exemplary embodiment;

[0023] Figure 6 A registration management state model in a UE according to an exemplary embodiment is shown;

[0024] Figure 7 shows connection management state transitions in a UE according to an exemplary embodiment;

[0025] FIG8 illustrates a network slice-specific authentication and authorization method according to an exemplary embodiment;

[0026] Fig. 9 A method of registering a UE to multiple SIMs according to an exemplary embodiment is shown;

[0027] Fig.10 A method of partial registration according to an exemplary embodiment is shown;

[0028] Fig.11 An alternative method of partial registration according to an exemplary embodiment is shown;

[0029] Fig.12 A method of indirect registration according to an exemplary embodiment is shown;

[0030] Fig.13 An alternative method of indirect registration according to an exemplary embodiment is shown;

[0031] Fig.14 shows the RM-INACTIVE registration management state according to an exemplary embodiment;

[0032] Fig.15 A paging method for multi-SIM operation according to an exemplary embodiment is shown;

[0033] Fig.16A SIM switching method according to an exemplary embodiment is shown;

[0034] Fig.17 shows a multi-SIM configuration GUI according to an exemplary embodiment;

[0035] Fig.18 shows an individual SIM configuration GUI according to an exemplary embodiment;

[0036] Fig.19 A 3GPP EPS non-roaming system architecture according to an exemplary embodiment is shown;

[0037] FIG. 20 illustrates an EPS attachment process according to an exemplary embodiment;

[0038] Fig.21 shows EPS Mobility Management (EMM) states according to an exemplary embodiment;

[0039] Fig. 22 shows EPS connection management states according to an exemplary embodiment;

[0040] Fig.23 shows a service request process triggered by an EPS network according to an exemplary embodiment;

[0041] Fig.24 A method of partial attachment according to an exemplary embodiment is shown;

[0042] Fig.25 A method of indirect attachment according to an exemplary embodiment is shown;

[0043] Fig.26 A method of multiple SIM attachment according to an exemplary embodiment is shown;

[0044] Fig. 27 shows an EMM-INACTIVE state according to an exemplary embodiment;

[0045] Fig.28 A method of forwarding a paging request for a UE in an ECM-CONNECTED state according to an exemplary embodiment is shown;

[0046] Fig.29 A method for forwarding a paging request for a UE in an ECM-IDLE state according to an exemplary embodiment is shown;

[0047] Fig.30 A method of inactivity registration timer update according to an exemplary embodiment is shown;

[0048] Fig.31 A method for an error condition caused by a SIM switch according to an exemplary embodiment is shown;

[0049] Fig.32 A non-roaming architecture for interworking between 5GS and EPS according to an exemplary embodiment is shown;

[0050] Fig.33 shows another multi-SIM configuration GUI according to an exemplary embodiment;

[0051] Fig.34 It shows that a UE according to an exemplary embodiment requests a core network to provide a temporary identifier;

[0052] Fig.35 shows a multi-SIM UE detecting a paging conflict according to an exemplary embodiment;

[0053] Fig.36 shows a process for activating and deactivating a registration pending timer according to an exemplary embodiment;

[0054] Fig.37 shows a UE performing a request to stop the core network from paging the UE according to an exemplary embodiment;

[0055] Fig.38 The core network according to an exemplary embodiment is shown providing a notification to a UE showing a missed page;

[0056] Fig.39 A method for a multi-SIM UE to perform indirect registration of an inactive SIM through a user plane of an active SIM according to an exemplary embodiment is shown;

[0057] Fig.40 shows a method for a multi-SIM UE to receive a NAS notification for SIM2 from PLMN2 through a user plane of PLMN1 according to an exemplary embodiment; and

[0058] Fig.41 A method according to an exemplary embodiment is shown in which a multi-SIM UE provides a core network with user configuration and user preferences for how the user wants the UE to behave with respect to multi-SIM operation.

[0059] Further areas of applicability of the present disclosure will become apparent from the detailed description provided hereinafter.It should be understood that the detailed description of the exemplary embodiments is for illustration purposes only, and is therefore not intended to necessarily limit the scope of the present disclosure. DETAILED DESCRIPTION

[0060] The Third Generation Partnership Project (3GPP) develops technical standards for cellular telecommunication network technologies, including radio access, core transport networks, and service capabilities - including work on codecs, security, and quality of service. Recent radio access technology (RAT) standards include WCDMA (commonly referred to as 3G), LTE (commonly referred to as 4G), LTE-Advanced standards, and New Radio (NR), also referred to as "5G". The development of 3GPP NR standards is expected to continue and include the definition of next generation radio access technologies (new RATs), which are expected to include the provision of new flexible radio access below 7 GHz, and the provision of new ultra-mobile broadband radio access above 7 GHz. Flexible radio access is expected to include new, non-backwards compatible radio access in new spectrum below 7 GHz, and is expected to include different operating modes that can be multiplexed together in the same spectrum to address a wide set of 3GPP NR use cases with different requirements. Ultra-mobile broadband is expected to include cmWave and mmWave spectrum, which will provide opportunities for ultra-mobile broadband access for, for example, indoor applications and hotspots. In particular, ultra-mobile broadband is expected to share a common design framework with sub-7 GHz flexible radio access, with cmWave- and mmWave-specific design optimizations.

[0061] 3GPP has identified a variety of use cases that NR is expected to support, resulting in a wide variety of user experience requirements for data rates, latency, and mobility. Use cases include the following general categories: enhanced mobile broadband (eMBB) ultra-reliable low-latency communications (URLLC), massive machine-type communications (mMTC), network operations (e.g., network slicing, routing, migration and interworking, energy saving), and enhanced vehicle-to-everything (eV2X) communications (which may include vehicle-to-vehicle communications (V2V), vehicle-to-infrastructure communications (V2I), vehicle-to-network communications (V2N), vehicle-to-pedestrian communications (V2P), and any of vehicle communications with other entities). Specific services and applications in these categories include, for example, surveillance and sensor networks, device remote control, two-way remote control, personal cloud computing, video streaming, wireless cloud-based offices, first responder connectivity, car emergency calls, disaster alerts, real-time gaming, multi-person video calls, autonomous driving, augmented reality, tactile Internet, virtual reality, home automation, robotics, and aerial drones, among others. All of these use cases and others are contemplated herein.

[0062] The following is a list of acronyms related to service levels and core network technologies that may appear in the following descriptions. Unless otherwise stated, acronyms used in this article refer to the corresponding terms listed below.

[0063] abbreviation

[0064]

[0065]

[0066] Terms and Definitions

[0067]

[0068]

[0069] Example Communication Systems and Networks

[0070] Figure 1A An example communication system 100 is illustrated in which the systems, methods, and apparatus described and claimed herein may be used. The communication system 100 may include wireless transmit / receive units (WTRUs) 102a, 102b, 102c, 102d, 102e, 102f, and / or 102g (generally or collectively referred to as WTRUs 102 or multiple WTRUs 102). The communication system 100 may include a radio access network (RAN) 103 / 104 / 105 / 103b / 104b / 105b, a core network 106 / 107 / 109, a public switched telephone network (PSTN) 108, the Internet 110, other networks 112, and network services 113. The network services 113 may include, for example, V2X servers, V2X functions, ProSe servers, ProSe functions, IoT services, video streaming, and / or edge computing, etc.

[0071] It will be appreciated that the concepts disclosed herein may be used with any number of WTRUs, base stations, networks, and / or network elements. Each of the WTRUs 102 may be any type of device or apparatus configured to operate and / or communicate in a wireless environment. Figure 1A In the example of FIG. 1 , each of the WTRUs 102 is Figures 1A-1E . It should be understood that for various use cases contemplated for wireless communication, each WTRU may include or be included in any type of device or apparatus configured to transmit and / or receive wireless signals, including, by way of example only, a user equipment (UE), a mobile station, a fixed or mobile subscriber unit, a pager, a cellular phone, a personal digital assistant (PDA), a smart phone, a laptop, a tablet, a netbook, a notebook computer, a personal computer, a wireless sensor, a consumer electronics product, a wearable device (such as a smart watch or smart clothing), a medical or e-health device, a robot, an industrial equipment, a drone, a vehicle (such as a car, bus or truck, a train or airplane), and the like.

[0072] The communication system 100 may also include a base station 114a and a base station 114b. Figure 1A In the example of FIG. 1 , each base station 114 a and 114 b is depicted as a single element. In practice, the base stations 114 a and 114 b may include any number of interconnected base stations and / or network elements. The base station 114 a may be any type of device configured to wirelessly interface with at least one of the WTRUs 102 a, 102 b, and 102 c to facilitate access to one or more communication networks (e.g., the core network 106 / 107 / 109, the Internet 110, network services 113, and / or other networks 112). Similarly, the base station 114b may be any type of device configured to interface wired and / or wirelessly with at least one of the remote radio heads (RRHs) 118a, 118b, the transmission and reception points (TRPs) 119a, 119b, and / or the roadside units (RSUs) 120a and 120b to facilitate access to one or more communication networks, such as the core network 106 / 107 / 109, the Internet 110, the other networks 112, and / or the network services 113. The RRHs 118a, 118b may be any type of device configured to wirelessly interface with at least one of the WTRUs 102 (e.g., WTRU 102c) to facilitate access to one or more communication networks, such as the core network 106 / 107 / 109, the Internet 110, the network services 113, and / or the other networks 112.

[0073] The TRPs 119a, 119b may be any type of device configured to wirelessly interface with at least one of the WTRUs 102d to facilitate access to one or more communication networks, such as the core network 106 / 107 / 109, the Internet 110, network services 113, and / or other networks 112. The RSUs 120a and 120b may be any type of device configured to wirelessly interface with at least one of the WTRUs 102e or 102f to facilitate access to one or more communication networks, such as the core network 106 / 107 / 109, the Internet 110, other networks 112, and / or network services 113. By way of example, the base stations 114a, 114b may be base transceiver stations (BTSs), Node Bs, eNode Bs, Home Node Bs, Home eNode Bs, next generation Node Bs (gNodeBs), satellites, site controllers, access points (APs), wireless routers, and the like.

[0074] The base station 114a may be part of the RAN 103 / 104 / 105, which may also include other base stations and / or network elements (not shown), such as a base station controller (BSC) 2302, a radio network controller (RNC), a relay node, etc. Similarly, the base station 114b may be part of the RAN 103b / 104b / 105b, which may also include other base stations and / or network elements (not shown), such as a BSC, an RNC, a relay node, etc. The base station 114a may be configured to transmit and / or receive wireless signals within a specific geographic area, which may be referred to as a cell (not shown). Similarly, the base station 114b may be configured to transmit and / or receive wired and / or wireless signals within a specific geographic area, which may be referred to as a cell (not shown). The cell may also be divided into cell sectors. For example, the cell associated with the base station 114a may be divided into three sectors. Thus, for example, the base station 114a may include three transceivers, for example, one for each sector of the cell. The base station 114a may employ multiple-input multiple-output (MIMO) technology and, therefore, may utilize multiple transceivers for each sector of the cell, for example.

[0075] The base station 114a may communicate with one or more of the WTRUs 102a, 102b, 102c, and 102g over an air interface 115 / 116 / 117, which may be any suitable wireless communication link (e.g., radio frequency (RF), microwave, infrared (IR), ultraviolet (UV), visible light, cmWave, mmWave, etc.). The air interface 115 / 116 / 117 may be established using any suitable radio access technology (RAT).

[0076] The base station 114b may communicate with one or more of the RRHs 118a and 118b, the TRPs 119a and 119b, and / or the RSUs 120a and 120b over a wired or air interface 115b / 116b / 117b, which may be any suitable wired (e.g., cable, fiber optic, etc.) or wireless communication link (e.g., RF, microwave, IR, UV, visible light, cmWave, mmWave, etc.). The air interface 115b / 116b / 117b may be established using any suitable RAT.

[0077] The RRHs 118a, 118b, TRPs 119a, 119b and / or RSUs 120a, 120b may communicate with one or more of the WTRUs 102c, 102d, 102e, 102f via an air interface 115c / 116c / 117c, which may be any suitable wireless communication link (e.g., RF, microwave, IR, ultraviolet UV, visible light, cmWave, mmWave, etc.). The air interface 115c / 116c / 117c may be established using any suitable RAT.

[0078] The WTRUs 102 may communicate with each other via a direct air interface 115d / 116d / 117d, such as a sidelink communication, which may be any suitable wireless communication link (e.g., RF, microwave, IR, ultraviolet UV, visible light, cmWave, mmWave, etc.). The air interface 115d / 116d / 117d may be established using any suitable RAT.

[0079] The communication system 100 may be a multiple-access system and may employ one or more channel access schemes such as CDMA, TDMA, FDMA, OFDMA, SC-FDMA, etc. For example, the base station 114a in the RAN 103 / 104 / 105 and the WTRUs 102a, 102b, 102c or the RRHs 118a, 118b, TRPs 119a, 119b and / or RSUs 120a and 120b in the RAN 103b / 104b / 105b and the WTRUs 102c, 102d, 102e, and 102f may implement a radio technology such as Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access (UTRA), which may use Wideband CDMA (WCDMA) to establish the air interfaces 115 / 116 / 117 and / or 115c / 116c / 117c, respectively. WCDMA may include communication protocols such as High Speed ​​Packet Access (HSPA) and / or Evolved HSPA (HSPA+). HSPA may include High Speed ​​Downlink Packet Access (HSDPA) and / or High Speed ​​Uplink Packet Access (HSUPA).

[0080] The base station 114a in the RAN 103 / 104 / 105 and the WTRUs 102a, 102b, 102c and 102g, or the RRHs 118a and 118b, TRPs 119a and 119b and / or RSUs 120a and 120b and the WTRUs 102c and 102d in the RAN 103b / 104b / 105b may implement a radio technology such as Evolved UMTS Terrestrial Radio Access (E-UTRA), which may establish an air interface 115 / 116 / 117 or 115c / 116c / 117c, respectively, using, for example, Long Term Evolution (LTE) and / or LTE-Advanced (LTE-A). The air interface 115 / 116 / 117 or 115c / 116c / 117c may implement 3GPP NR technology. LTE and LTE-A technologies may include LTE D2D and / or V2X technologies and interfaces (such as sidelink communications, etc.). Similarly, 3GPP NR technologies may include NR V2X technologies and interfaces (such as sidelink communications, etc.).

[0081] The base station 114a in the RAN 103 / 104 / 105 and the WTRUs 102a, 102b, 102c, and 102g or the RRHs 118a and 118b, the TRPs 119a and 119b and / or the RSUs 120a and 120b and the WTRUs 102c, 102d, 102e, and 102f in the RAN 103b / 104b / 105b may implement a radio technology such as IEEE 802.16 (e.g., Worldwide Interoperability for Microwave Access (WiMAX)), CDMA2000, CDMA2000 IX, CDMA2000EV-DO, Interim Standard 2000 (IS-2000), Interim Standard 95 (IS-95), Interim Standard 856 (IS-856), Global System for Mobile Communications (GSM), Enhanced Data Rates for GSM Evolution (EDGE), GSM EDGE (GERAN) etc.

[0082] For example, Figure 1AThe base station 114c in the example may be a wireless router, a Home Node B, a Home eNode B, or an access point, and may utilize any suitable RAT to facilitate wireless connectivity in a localized area, such as a business location, a house, a vehicle, a train, an antenna, a satellite, a factory, a campus, etc. The base station 114c and the WTRU 102 (e.g., WTRU 102e) may implement radio technologies such as IEEE 802.11 to establish a wireless local area network (WLAN). Similarly, the base station 114c and the WTRU 102 (e.g., WTRU 102d) may implement radio technologies such as IEEE 802.15 to establish a wireless personal area network (WPAN). The base station 114c and the WTRU 102 (e.g., WTRU 102e) may utilize a cellular-based RAT (e.g., WCDMA, CDMA2000, GSM, LTE, LTE-A, NR, etc.) to establish a picocell or a femtocell. Figure 1A As shown in FIG, the base station 114c may have a direct connection to the Internet 110. Therefore, the base station 114c may not be required to access the Internet 110 via the core network 106 / 107 / 109.

[0083] The RAN 103 / 104 / 105 and / or the RAN 103b / 104b / 105b may be in communication with a core network 106 / 107 / 109, which may be any type of network configured to provide voice, data, messaging, authorization and authentication, applications, and / or Voice over Internet Protocol (VoIP) services to one or more of the WTRUs 102. For example, the core network 106 / 107 / 109 may provide call control, billing services, mobile location-based services, pre-paid calling, Internet connectivity, packet data network connectivity, Ethernet connectivity, video distribution, etc., and / or perform high-level security functions (such as user authentication).

[0084] Although not in Figure 1A 105b and / or the core network 106 / 107 / 109 may be in direct or indirect communication with other RANs that employ the same RAT as the RAN 103 / 104 / 105 and / or the RAN 103b / 104b / 105b or a different RAT. For example, in addition to being connected to the RAN 103 / 104 / 105 and / or the RAN 103b / 104b / 105b, which may utilize an E-UTRA radio technology, the core network 106 / 107 / 109 may also be in communication with another RAN (not shown) that employs a GSM or NR radio technology.

[0085] The core network 106 / 107 / 109 may also serve as a gateway for the WTRU 102 to access the PSTN 108, the Internet 110, and / or other networks 112. The PSTN 108 may include a circuit-switched telephone network that provides plain old telephone service (POTS). The Internet 110 may include a global system of interconnected computer networks and devices using common communication protocols, such as the Transmission Control Protocol (TCP), the User Datagram Protocol (UDP), and the Internet Protocol (IP) in the TCP / IP Internet Protocol suite. Other networks 112 may include wired or wireless communication networks owned and / or operated by other service providers. For example, the networks 112 may include any type of packet data network (e.g., an IEEE 802.3 Ethernet network) or another core network connected to one or more RANs, which may employ the same RAT as the RAN 103 / 104 / 105 and / or the RAN 103b / 104b / 105b or a different RAT.

[0086] Some or all of the WTRUs 102a, 102b, 102c, 102d, 102e, and 102f in the communication system 100 may include multi-mode capabilities, e.g., the WTRUs 102a, 102b, 102c, 102d, 102e, and 102f may include multiple transceivers for communicating with different wireless networks via different wireless links. Figure 1A The WTRU 102g shown in FIG. 1 may be configured to communicate with the base station 114a, which may employ a cellular-based radio technology, and with the base station 114c, which may employ an IEEE 802 radio technology.

[0087] Although in Figure 1A 106 / 107 / 109. It will be appreciated that many of the concepts contained herein are equally applicable to a UE that is a WTRU and a UE that uses a wired connection to connect to a network. For example, concepts applicable to wireless interfaces 115, 116, 117, and 115c / 116c / 117c may be equally applicable to a wired connection.

[0088] Figure 1B 1 is a system diagram of an example RAN 103 and a core network 106. As described above, the RAN 103 may employ a UTRA radio technology to communicate with the WTRUs 102a, 102b, and 102c over the air interface 115. The RAN 103 may also be in communication with the core network 106. Figure 1BAs shown in FIG. 1 , the RAN 103 may include Node-Bs 140a, 140b, and 140c, which may each include one or more transceivers for communicating with the WTRUs 102a, 102b, and 102c over the air interface 115. The Node-Bs 140a, 140b, and 140c may each be associated with a particular cell (not shown) within the RAN 103. The RAN 103 may also include RNCs 142a, 142b. It will be appreciated that the RAN 103 may include any number of Node-Bs and Radio Network Controllers (RNCs).

[0089] like Figure 1B As shown in , Node B 140a, 140b can communicate with RNC 142a. In addition, Node B 140c can communicate with RNC 142b. Node B 140a, 140b and 140c can communicate with corresponding RNC 142a and 142b via Iub interface. RNC 142a and 142b can communicate with each other via Iur interface. Each of RNC 142a and 142b can be configured to control the corresponding Node B 140a, 140b and 140c to which it is connected. In addition, each of RNC 142a and 142b can be configured to perform or support other functions, such as outer loop power control, load control, admission control, packet scheduling, handover control, macro diversity, security function, data encryption, etc.

[0090] Figure 1B The core network 106 shown in FIG. 1 may include a media gateway (MGW) 144, a mobile switching center (MSC) 146, a serving GPRS support node (SGSN) 148, and / or a gateway GPRS support node (GGSN) 150. Although each of the foregoing elements is depicted as part of the core network 106, it will be appreciated that any of these elements may be owned and / or operated by an entity other than the core network operator.

[0091] The RNC 142a in the RAN 103 may be connected to the MSC 146 in the core network 106 via an IuCS interface. The MSC 146 may be connected to the MGW 144. The MSC 146 and the MGW 144 may provide the WTRUs 102a, 102b, and 102c with access to circuit-switched networks, such as the PSTN 108, to facilitate communications between the WTRUs 102a, 102b, and 102c and traditional land-line communications devices.

[0092] The RNC 142a in the RAN 103 may also be connected to the SGSN 148 in the core network 106 via an IuPS interface. The SGSN 148 may be connected to the GGSN 150. The SGSN 148 and the GGSN 150 may provide the WTRUs 102a, 102b, and 102c with access to packet-switched networks, such as the Internet 110, to facilitate communications between the WTRUs 102a, 102b, and 102c and IP-enabled devices.

[0093] The core network 106 may also be connected to other networks 112, which may include other wired or wireless networks owned and / or operated by other service providers.

[0094] Figure 1C 1 is a system diagram of an example RAN 104 and a core network 107. As noted above, the RAN 104 may employ an E-UTRA radio technology to communicate with the WTRUs 102a, 102b, and 102c over the air interface 116. The RAN 104 may also be in communication with the core network 107.

[0095] The RAN 104 may include eNode-Bs 160a, 160b, and 160c, although it will be appreciated that the RAN 104 may include any number of eNode-Bs. The eNode-Bs 160a, 160b, and 160c may each include one or more transceivers for communicating with the WTRUs 102a, 102b, and 102c over the air interface 116. For example, the eNode-Bs 160a, 160b, and 160c may implement MIMO technology. Thus, for example, the eNode-B 160a may use multiple antennas to transmit wireless signals to, and receive wireless signals from, the WTRU 102a.

[0096] Each of the eNode-Bs 160a, 160b, and 160c may be associated with a particular cell (not shown) and may be configured to handle radio resource management decisions, handover decisions, user scheduling in uplink and / or downlink, etc. Figure 1C As shown in FIG, eNode-Bs 160a, 160b, and 160c may communicate with each other via an X2 interface.

[0097] Figure 1C The core network 107 shown in FIG. 1 may include a mobility management gateway (MME) 162, a serving gateway 164, and a packet data network (PDN) gateway 166. While each of the aforementioned elements is depicted as part of the core network 107, it should be appreciated that any of these elements may be owned and / or operated by an entity other than the core network operator.

[0098] The MME 162 may be connected to each of the eNode-Bs 160a, 160b, and 160c in the RAN 104 via an S1 interface and may serve as a control node. For example, the MME 162 may be responsible for authenticating users of the WTRUs 102a, 102b, and 102c, bearer activation / deactivation, selecting a particular serving gateway during an initial attach of the WTRUs 102a, 102b, and 102c, etc. The MME 162 may also provide a control plane function for switching between the RAN 104 and other RANs (not shown) that employ other radio technologies, such as GSM or WCDMA.

[0099] The serving gateway 164 may be connected to each of the eNode-Bs 160a, 160b, and 160c in the RAN 104 via an S1 interface. The serving gateway 164 may generally route and forward user data packets to / from the WTRUs 102a, 102b, and 102c. The serving gateway 164 may also perform other functions, such as anchoring a user plane during an inter-eNode B handover, triggering paging when downlink data is available for the WTRUs 102a, 102b, and 102c, managing and storing contexts of the WTRUs 102a, 102b, and 102c, and the like.

[0100] The serving gateway 164 may also be connected to the PDN gateway 166, which may provide the WTRUs 102a, 102b, and 102c with access to packet-switched networks, such as the Internet 110, to facilitate communications between the WTRUs 102a, 102b, 102c and IP-enabled devices.

[0101] The core network 107 may facilitate communications with other networks. For example, the core network 107 may provide the WTRUs 102a, 102b, and 102c with access to circuit-switched networks, such as the PSTN 108, to facilitate communications between the WTRUs 102a, 102b, and 102c and traditional land-line communications devices. For example, the core network 107 may include or may communicate with an IP gateway (e.g., an IP Multimedia Subsystem (IMS) server) that acts as an interface between the core network 107 and the PSTN 108. In addition, the core network 107 may provide the WTRUs 102a, 102b, and 102c with access to the networks 112, which may include other wired or wireless networks owned or operated by other service providers.

[0102] Figure 1D1 is a system diagram of an example RAN 105 and a core network 109. The RAN 105 may employ NR radio technology to communicate with the WTRUs 102a and 102b over the air interface 117. The RAN 105 may also be in communication with the core network 109. A non-3GPP interworking function (N3IWF) 199 may employ non-3GPP radio technology to communicate with the WTRU 102c over the air interface 198. The N3IWF 199 may also be in communication with the core network 109.

[0103] The RAN 105 may include gNode-Bs 180a and 180b. It will be appreciated that the RAN 105 may include any number of gNode-Bs. The gNode-Bs 180a and 180b may each include one or more transceivers for communicating with the WTRUs 102a and 102b over the air interface 117. When an integrated access and backhaul connection is used, the same air interface may be used between the WTRUs and the gNode-Bs, which may be a core network 109 via one or more gNBs. The gNode-Bs 180a and 180b may implement MIMO, MU-MIMO, and / or digital beamforming techniques. Thus, for example, the gNode-B 180a may use multiple antennas to transmit wireless signals to and receive wireless signals from the WTRU 102a. It should be appreciated that the RAN 105 may employ other types of base stations, such as an eNode-B. It should also be appreciated that the RAN 105 may employ more than one type of base station. For example, RAN may employ eNode-B and gNode-B.

[0104] The N3IWF 199 may include a non-3GPP access point 180c. It will be appreciated that the N3IWF 199 may include any number of non-3GPP access points. The non-3GPP access point 180c may include one or more transceivers for communicating with the WTRU 102c over the air interface 198. The non-3GPP access point 180c may communicate with the WTRU 102c over the air interface 198 using the 802.11 protocol.

[0105] Each of the gNode-Bs 180a and 180b may be associated with a particular cell (not shown) and may be configured to handle radio resource management decisions, handover decisions, user scheduling in uplink and / or downlink, etc. Figure 1D As shown in , for example, gNode-Bs 180a and 180b may communicate with each other via an Xn interface.

[0106] Figure 1DThe core network 109 shown in the figure can be a 5G core network (5GC). The core network 109 can provide a variety of communication services to customers interconnected by a radio access network. The core network 109 includes multiple entities that perform the functions of the core network. As used herein, the term "core network entity" or "network function" refers to any entity that performs one or more functions of the core network. It should be understood that such a core network entity can be a device or computer system (such as a 5G core network) stored in a device or computer system configured for wireless and / or network communications. Figure 1G A logical entity implemented in the form of computer-executable instructions (software) stored in a memory of the system 90 shown in FIG. 1 and executed on a processor thereof.

[0107] exist Figure 1D In the example of , the 5G core network 109 may include access and mobility management function (AMF) 172, session management function (SMF) 174, user plane function (UPF) 176a and 176b, user data management function (UDM) 197, authentication server function (AUSF) 190, network exposure function (NEF) 196, policy control function (PCF) 184, non-3GPP interworking function (N3IWF) 199, user data repository (UDR) 178. Although each of the aforementioned elements is depicted as part of the 5G core network 109, it should be recognized that any of these elements may be owned and / or operated by an entity other than the core network operator. It will also be recognized that the 5G core network may not consist of all of these elements, may consist of additional elements, and may consist of multiple instances of each of these elements. Figure 1D The network functions are shown connected directly to each other, however, it should be appreciated that they may communicate via a routing agent such as a diameter routing agent or a message bus.

[0108] exist Figure 1D In the example of , the connectivity between network functions is achieved via a set of interfaces or reference points. It will be appreciated that a network function can be modeled, described or implemented as a set of services called or caused by other network functions or services. The invocation of a network function service can be achieved via a direct connection between network functions, an exchange of messaging on a message bus, calling a software function, etc.

[0109] The AMF 172 may be connected to the RAN 105 via an N2 interface and may serve as a control node. For example, the AMF 172 may be responsible for registration management, connection management, reachability management, access authentication, access authorization. The AMF may be responsible for forwarding user plane tunnel configuration information to the RAN 105 via the N2 interface. The AMF 172 may receive user plane tunnel configuration information from the SMF via the N11 interface. The AMF 172 may generally route and forward NAS packets to / from the WTRUs 102a, 102b, and 102c via the N1 interface. The N1 interface is not used in Figure 1D Shown in.

[0110] The SMF 174 may be connected to the AMF 172 via an N11 interface. Similarly, the SMF may be connected to the PCF 184 via an N7 interface and to the UPFs 176a and 176b via an N4 interface. The SMF 174 may serve as a control node. For example, the SMF 174 may be responsible for session management, IP address allocation for the WTRUs 102a, 102b, and 102c, management and configuration of traffic steering rules in the UPFs 176a and 176b, and generation of downlink data notifications to the AMF 172.

[0111] The UPF 176a and UPF 176b may provide the WTRUs 102a, 102b, and 102c with access to a packet data network (PDN), such as the Internet 110, to facilitate communication between the WTRUs 102a, 102b, and 102c and other devices. The UPF 176a and UPF 176b may also provide the WTRUs 102a, 102b, and 102c with access to other types of packet data networks. For example, the other network 112 may be an Ethernet network or any type of network that exchanges packets of data. The UPF 176a and UPF 176b may receive traffic steering rules from the SMF 174 via an N4 interface. The UPF 176a and UPF 176b may provide access to a packet data network by connecting the packet data network to an N6 interface or by connecting to each other and to other UPFs via an N9 interface. In addition to providing access to the packet data network, UPF 176 may also be responsible for packet routing and forwarding, policy rule enforcement, quality of service handling of user plane traffic, and downlink packet buffering.

[0112] The AMF 172 may also be connected to the N3IWF 199, for example, via an N2 interface. The N3IWF facilitates connectivity between the WTRU 102c and the 5G core network 170, for example, via a 3GPP undefined radio interface technology. The AMF may interact with the N3IWF 199 in the same or similar manner as it interacts with the RAN 105.

[0113] PCF 184 may be connected to SMF 174 via an N7 interface, may be connected to AMF 172 via an N15 interface, and may be connected to application function (AF) 188 via an N5 interface. The N15 and N5 interfaces are not Figure 1D 1. The PCF 184 may provide policy rules to control plane nodes such as the AMF 172 and the SMF 174, thereby allowing the control plane nodes to enforce these rules. The PCF 184 may send policies for the WTRUs 102a, 102b, and 102c to the AMF 172 so that the AMF may deliver the policies to the WTRUs 102a, 102b, and 102c via the N1 interface. The policies may then be enforced or applied at the WTRUs 102a, 102b, and 102c.

[0114] The UDR 178 may act as a repository for authentication credentials and subscription information. The UDR may be connected to a network function so that the network function can add data to the repository, read and modify data in the repository. For example, the UDR 178 may be connected to the PCF 184 via an N36 interface. Similarly, the UDR 178 may be connected to the NEF 196 via an N37 interface, and the UDR 178 may be connected to the UDM 197 via an N35 interface.

[0115] The UDM 197 may serve as an interface between the UDR 178 and other network functions. The UDM 197 may authorize network functions to access the UDR 178. For example, the UDM 197 may be connected to the AMF 172 via the N8 interface, and the UDM 197 may be connected to the SMF 174 via the N10 interface. Similarly, the UDM 197 may be connected to the AUSF 190 via the N13 interface. The UDR 178 and the UDM 197 may be tightly integrated.

[0116] The AUSF 190 performs operations related to authentication and is connected to the UDM 178 via the N13 interface and to the AMF 172 via the N12 interface.

[0117] NEF 196 exposes the capabilities and services in the 5G core network 109 to the application function (AF) 188. The exposure can occur on the N33 API interface. NEF can be connected to AF 188 via the N33 interface and it can be connected to other network functions to expose the capabilities and services of the 5G core network 109.

[0118] The application function 188 may interact with the network function in the 5G core network 109. The interaction between the application function 188 and the network function may occur via a direct interface or may occur via the NEF 196. The application function 188 may be considered part of the 5G core network 109 or may be external to the 5G core network 109 and deployed by an enterprise having a business relationship with a mobile network operator.

[0119] Network slicing is a mechanism that mobile network operators can use to support one or more "virtual" core networks behind the operator's air interface. This involves "slicing" the core network into one or more virtual networks to support different RANs or different service types running across a single RAN. Network slicing enables operators to create networks that are customized to provide optimized solutions for different market scenarios that require different requirements (for example, in terms of functionality, performance and isolation).

[0120] 3GPP has designed the 5G core network to support network slicing. Network slicing is a great tool that network operators can use to support a diverse set of 5G use cases (e.g., massive IoT, critical communications, V2X, and enhanced mobile broadband) that have very diverse and sometimes extreme requirements. Without using network slicing technology, the network architecture may not be flexible and scalable enough to efficiently support a wide range of use case requirements when each use case has its own specific set of performance, scalability, and availability requirements. In addition, the introduction of new network services should be made more efficient.

[0121] Reference again Figure 1D In a network slicing scenario, the WTRU 102a, 102b, or 102c may be connected to the AMF 172 via the N1 interface. The AMF may logically be part of one or more slices. The AMF may coordinate the connection or communication of the WTRU 102a, 102b, or 102c with one or more UPFs 176a and 176b, SMF 174, and other network functions. Each of the UPFs 176a and 176b, SMF 174, and other network functions may be part of the same slice or different slices. When they are part of different slices, they may be isolated from each other in the sense that they may utilize different computing resources, security credentials, etc.

[0122] The core network 109 may facilitate communications with other networks. For example, the core network 109 may include, or may communicate with, an IP gateway (such as an IP Multimedia Subsystem (IMS) server) that serves as an interface between the 5G core network 109 and the PSTN 108. For example, the core network 109 may include, or communicate with, a short message service (SMS) service center that facilitates communication via short message service. For example, the 5G core network 109 may facilitate the exchange of non-IP data packets between the WTRUs 102a, 102b, and 102c and a server or application function 188. In addition, the core network 170 may provide the WTRUs 102a, 102b, and 102c with access to the networks 112, which may include other wired or wireless networks owned and / or operated by other service providers.

[0123] This article describes and Figure 1A , 1C The core network entities shown in 1D and 1E are identified by the names given to those entities in certain existing 3GPP specifications, but it is understood that those entities and functions may be identified by other names in the future, and that certain entities or functions may be combined in future specifications published by 3GPP (including future 3GPP NR specifications). Therefore, the core network entities shown in 1D and 1E are identified by the names given to those entities in certain existing 3GPP specifications, but it is understood that those entities and functions may be identified by other names in the future, and that certain entities or functions may be combined in future specifications published by 3GPP (including future 3GPP NR specifications). Figure 1A , 1B , 1C, 1D and 1E, and it should be understood that the subject matter disclosed and claimed herein may be implemented or realized in any similar communication system (whether currently defined or defined in the future).

[0124] Figure 1E An example communication system 111 is illustrated in which the systems, methods, and apparatus described herein may be used. The communication system 111 may include wireless transmit / receive units (WTRUs) A, B, C, D, E, F, a base station gNB 121, a V2X server 124, and roadside units (RSUs) 123a and 123b. In practice, the concepts presented herein may be applied to any number of WTRUs, base stations gNBs, V2X networks, and / or other network elements. One or several or all of the WTRUs A, B, C, D, E, and F may be outside the range of the access network coverage 122. WTRUs A, B, and C form a V2X group, where WTRU A is the group leader and WTRUs B and C are group members.

[0125] If WTRU A, B, C, D, E, F are within the coverage area of ​​the access network (in Figure 1E129b), they can communicate with each other via gNB 121 over the Uu interface 129b. If WTRUs A, B, C, D, E, and F are within or outside the access network coverage (e.g., within Figure 1E In the figure, WTRU A, B, C, D, E, and F can communicate with each other, and D and E are shown as outside the network coverage), then WTRU A, B, C, D, E, and F can communicate directly with each other via the side link (PC5 or NR PC5) interfaces 125a, 125b, and 128.

[0126] WTRUs A, B, C, D, E, and F may communicate with the RSU 123a or 123b via the vehicle-to-network (V2N) 126 or the sidelink interface 125b. WTRUs A, B, C, D, E, and F may communicate with the V2X server 124 via the vehicle-to-infrastructure (V2I) interface 127. WTRUs A, B, C, D, E, and F may communicate with another UE via the vehicle-to-person (V2P) interface 128.

[0127] Figure 1F is a block diagram of an example apparatus or device WTRU 102 that may be configured to wirelessly communicate and operate in accordance with the systems, methods, and apparatus described herein, such as Figure 1A , 1B , 1C, 1D, or 1E. Figure 1F As shown in FIG, the example WTRU 102 may include a processor 118, a transceiver 120, a transmit / receive element 122, a speaker / microphone 124, a keypad 126, a display / touchpad / indicator 128, a non-removable memory 130, a removable memory 132, a power supply 134, a global positioning system (GPS) chipset 136, and other peripherals 138. It will be appreciated that the WTRU 102 may include any sub-combination of the foregoing elements, and that the base stations 114a and 114b and / or the nodes that the base stations 114a and 114b may represent (such as, but not limited to, a transceiver station (BTS), a Node B, a site controller, an access point (AP), a Home Node B, an evolved Home Node B (eNodeB), a Home evolved Node B (HeNB), a Home evolved Node B gateway, a next generation Node B (gNode-B), and a proxy node, among others) may include Figure 1F Some or all of the elements depicted in and described herein.

[0128] The processor 118 may be a general purpose processor, a special purpose processor, a conventional processor, a digital signal processor (DSP), a plurality of microprocessors, one or more microprocessors associated with a DSP core, a controller, a microcontroller, an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) circuit, any other type of integrated circuit (IC), a state machine, etc. The processor 118 may perform signal coding, data processing, power control, input / output processing, and / or any other functionality that enables the WTRU 102 to operate in a wireless environment. The processor 118 may be coupled to the transceiver 120, which may be coupled to the transmit / receive element 122. Although Figure 1F The processor 118 and the transceiver 120 are depicted as separate components, but it will be appreciated that the processor 118 and the transceiver 120 may be integrated together in an electronic package or chip.

[0129] The transmit / receive element 122 of the UE may be configured to transmit data to a base station (eg, Figure 1A The transmission / reception element 122 may be a base station 114a) of a wireless communication network, or may transmit or receive signals to or from another UE via an air interface 115d / 116d / 117d. For example, the transmission / reception element 122 may be an antenna configured to transmit and / or receive RF signals. The transmission / reception element 122 may be a transmitter / detector configured to, for example, transmit and / or receive IR, UV, or visible light signals. The transmission / reception element 122 may be configured to transmit and receive both RF and optical signals. It will be appreciated that the transmission / reception element 122 may be configured to transmit and / or receive any combination of wireless or wired signals.

[0130] In addition, although the transmit / receive element 122 is Figure 1F Although depicted as a single element in the figure, the WTRU 102 may include any number of transmit / receive elements 122. More specifically, the WTRU 102 may employ MIMO technology. Thus, the WTRU 102 may include two or more transmit / receive elements 122 (e.g., multiple antennas) for transmitting and receiving wireless signals over the air interface 115 / 116 / 117.

[0131] The transceiver 120 may be configured to modulate signals to be transmitted by the transmit / receive element 122 and demodulate signals received by the transmit / receive element 122. As described above, the WTRU 102 may have multi-mode capabilities. Thus, the transceiver 120 may include multiple transceivers to enable the WTRU 102 to communicate via multiple RATs (e.g., NR and IEEE 802.11 or NR and E-UTRA) or to communicate with the same RAT via multiple beams to different RRHs, TRPs, RSUs, or nodes.

[0132] The processor 118 of the WTRU 102 may be coupled to a speaker / microphone 124, a keypad 126, and / or a display / touchpad / indicator 128 (e.g., a liquid crystal display (LCD) display unit or an organic light emitting diode (OLED) display unit), and may receive user input data therefrom. The processor 118 may also output user data to the speaker / microphone 124, the keypad 126, and / or the display / touchpad / indicator 128. In addition, the processor 118 may access information from and store data in any type of suitable memory, such as a non-removable memory 130 and / or a removable memory 132. The non-removable memory 130 may include a random access memory (RAM), a read-only memory (ROM), a hard disk, or any other type of memory storage device. The removable memory 132 may include a subscriber identity module (SIM) card, a memory stick, a secure digital (SD) memory card, or the like. The processor 118 may access information from, and store data in, memory that is not physically located on the WTRU 102, such as on a server hosted in a cloud or edge computing platform or in a home computer (not shown).

[0133] The processor 118 may receive power from the power source 134, and may be configured to distribute and / or control the power to other components in the WTRU 102. The power source 134 may be any suitable device for powering the WTRU 102. For example, the power source 134 may include one or more dry cell batteries, solar cells, fuel cells, etc.

[0134] The processor 118 may also be coupled to the GPS chipset 136, which may be configured to provide location information (e.g., longitude and latitude) regarding the current location of the WTRU 102. In addition to or in lieu of the information from the GPS chipset 136, the WTRU 102 may receive location information from a base station (e.g., base stations 114a, 114b) over the air interface 115 / 116 / 117 and / or determine its location based on the timing of receiving signals from two or more nearby base stations. It will be appreciated that the WTRU 102 may acquire location information by any suitable location-determination method.

[0135] The processor 118 may also be coupled to other peripherals 138, which may include one or more software and / or hardware modules that provide additional features, functionality, and / or wired or wireless connectivity. For example, the peripherals 138 may include various sensors such as accelerometers, biometric (e.g., fingerprint) sensors, electronic compasses, satellite transceivers, digital cameras (for photos or videos), universal serial bus (USB) ports or other interconnect interfaces, vibration devices, television transceivers, hands-free headsets, modules, FM radio units, digital music players, media players, video game player modules, internet browsers, etc.

[0136] The WTRU 102 may be included in other devices or equipment, such as sensors, consumer electronics, wearable devices (such as smart watches or smart clothing), medical or e-health equipment, robots, industrial equipment, drones, vehicles (such as cars, trucks, trains, or airplanes). The WTRU 102 may be connected to other components, modules, or systems of such devices or equipment via one or more interconnect interfaces (such as an interconnect interface that may include one of the peripheral devices 138).

[0137] Figure 1G is a block diagram of an exemplary computing system 90 in which Figure 1A , 1C , 1D and 1E, such as certain nodes or functional entities in the RAN 103 / 104 / 105, the core network 106 / 107 / 109, the PSTN 108, the Internet 110, other networks 112 or network services 113. The computing system 90 may include a computer or a server and may be primarily controlled by computer-readable instructions, which may be in the form of software, wherever or by whatever means such software is stored or accessed. Such computer-readable instructions may be executed within the processor 91 to enable the computing system 90 to operate. The processor 91 may be a general-purpose processor, a special-purpose processor, a conventional processor, a digital signal processor (DSP), a plurality of microprocessors, one or more microprocessors associated with a DSP core, a controller, a microcontroller, an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA) circuit, any other type of integrated circuit (IC), a state machine, etc. The processor 91 may perform signal encoding, data processing, power control, input / output processing and / or any other function that enables the computing system 90 to operate in a communication network. Coprocessor 81 is an optional processor distinct from main processor 91 that may perform additional functions or assist processor 91. Processor 91 and / or coprocessor 81 may receive, generate, and process data related to the methods and apparatus disclosed herein.

[0138] In operation, processor 91 fetches, decodes and executes instructions, and transfers information to and from other resources via the computing system's main data transfer path, system bus 80. Such a system bus connects components in computing system 90 and defines a medium for data exchange. System bus 80 typically includes data lines for sending data, address lines for sending addresses, and control lines for sending interrupts and for operating the bus. An example of such a system bus 80 is a PCI (Peripheral Component Interconnect) bus.

[0139] The memory coupled to the system bus 80 includes a random access memory (RAM) 82 and a read-only memory (ROM) 93. Such memory includes a circuit system that allows information to be stored and retrieved. ROM 93 generally contains stored data that is not easily modified. The data stored in RAM 82 can be read or changed by a processor 91 or other hardware device. Access to RAM 82 and / or ROM 93 can be controlled by a memory controller 92. The memory controller 92 can provide an address translation function that translates a virtual address into a physical address when an instruction is executed. The memory controller 92 can also provide a memory protection function that isolates processes within the system and isolates system processes from user processes. Therefore, a program running in the first mode can only access memory mapped by its own process virtual address space; unless memory sharing between processes has been set up, it cannot access memory within the virtual address space of another process.

[0140] In addition, the computing system 90 may include a peripheral device controller 83 that is responsible for transmitting instructions from the processor 91 to peripheral devices such as a printer 94 , a keyboard 84 , a mouse 95 , and a disk drive 85 .

[0141] The display 86 controlled by the display controller 96 is used to display the visual output generated by the computing system 90. Such visual output may include text, graphics, animated graphics, and video. The visual output may be provided in the form of a graphical user interface (GUI). The display 86 may be implemented with a CRT-based video display, an LCD-based flat panel display, a gas plasma-based flat panel display, or a touch pad. The display controller 96 includes the electronic components required to generate the video signal sent to the display 86.

[0142] In addition, the computing system 90 may include communication circuitry, such as, for example, a wireless or wired network adapter 97, which may be used to connect the computing system 90 to an external communication network or device (such as the RAN 103 / 104 / 105, the core network 106 / 107 / 109, the PSTN 108, the Internet 110, the WTRU 102, or Figure 1A , 1B, 1C, 1D and 1E) to enable the computing system 90 to communicate with other nodes or functional entities of those networks. Alone or in combination with the processor 91, the communication circuit system can be used to perform the transmission and reception steps of certain devices, nodes or functional entities described herein.

[0143] It should be understood that any or all of the devices, systems, methods, and processes described herein may be implemented in the form of computer executable instructions (e.g., program code) stored on a computer-readable storage medium, which, when executed by a processor (such as processor 118 or 91), causes the processor to perform and / or implement the systems, methods, and processes described herein. Specifically, any step, operation, or function described herein may be implemented in the form of such computer executable instructions executed on a processor of a device or computing system configured for wireless and / or wired network communication. Computer-readable storage media include volatile and non-volatile, removable and non-removable media implemented in any non-transient (e.g., tangible or physical) method or technology for storing information, but such computer-readable storage media do not include signals. Computer-readable storage media include, but are not limited to, RAM, ROM, EEPROM, flash memory or other memory technology, CD-ROM, digital versatile disk (DVD) or other optical disk storage, cassette, tape, disk storage or other magnetic storage device, or any other tangible or physical medium that can be used to store desired information and can be accessed by a computing system.

[0144] 5G system architecture

[0145] Figure 2 The 3GPP 5G non-roaming system architecture is shown, with various entities interacting with each other through the indicated reference points. A user equipment (UE) 102 can communicate with a core network (CN) to establish control signaling and enable the UE 102 to use services from the CN. Examples of control signaling functions are: registration, connection and mobility management, authentication and authorization, session management, etc.

[0146] Figure 2 The following network functions (NFs) in the CN are the main NFs in the control plane (CP) of the CN involved in control signaling:

[0147] Access and Mobility Function (AMF) 172: The UE 102 sends N1 messages to the AMF 172 through the RAN node 105 to perform a number of control plane signaling such as registration, connection management, mobility management, access authentication and authorization, etc.

[0148] • Session Management Function (SMF) 174: The SMF 174 is responsible for session management involving establishing PDU sessions to allow the UE to send data to a data network (DN) 208 (such as the Internet) or an application server and other session management related functions.

[0149] • Policy and Control Function (PCF) 184: PCF 184 provides a policy framework that governs network behavior, accesses subscription information to make policy decisions, etc.

[0150] • Authentication Server Function (AUSF) 190: The AUSF 190 supports authentication of UEs for both 3GPP and untrusted non-3GPP accesses.

[0151] Unified Data Management (UDM) 197: UDM 197 supports generation of 3GPP AKA authentication credentials, user identity handling, subscription management, etc.

[0152] Network Slice Selection Function (NSSF) 216: The NSSF 216 is involved in various aspects of network slice management, such as selection of a network slice instance for a UE, management of NSSAI, etc.

[0153] • Radio Access Network (RAN) 105: The RAN node 105 provides communication access from the UE 102 to the core network for control plane and user plane communications.

[0154] 5G roaming architecture

[0155] Figure 3 A 5G system roaming architecture for a local breakout scenario under a service-based representation is shown, where the VPLMN is the visited PLMN and the HPLMN is the home PLMN. A security edge protection proxy (SEPP) 304 enables communication between the VPLMN and the HPLMN.

[0156] Figure 4 The 5G system roaming architecture for the local branch scenario is shown in the form of reference point representation. In this figure, the SEPP is not depicted for clarity. The AMF in the VPLMN can communicate with the AUSF of the HPLMN over the N12 interface to authenticate the UE from the HPLMN. Policy information can be transmitted between the vPCF and the hPCF over the N24 interface.

[0157] 5G Registration Process

[0158] Before the UE can use the services provided by the CN, the UE must register with the core network. Figure 5 shows the 5G generic registration procedure from TS 23.502 [2], which the UE performs to register with the CN. The following are the steps worth noting in the generic registration process:

[0159] In step S500, the UE provides a registration type to indicate what the request is for. Two common types are initial registration, performed by the UE to first establish registration with the CN, and periodic registration updates, performed at periodic intervals to inform the CN that the UE still exists. In addition, the UE may provide an identifier such as a SUCI to the CN during the initial registration in step S510, which the CN uses to authenticate the UE.

[0160] In steps S502, S504, S506, S508, the AMF may obtain the SUCI of the UE if it is not provided in step S500.

[0161] In step S510, the AUSF authenticates the UE according to the subscription information provided by the UDM and the SUCI provided by the UE.

[0162] In step S512, the AMF returns a registration accept message to the UE, indicating the result of the registration process. For initial registration, the accept message includes a temporary identifier (such as 5G-GUTI), a list of allowed network slices, DRX parameters, and other relevant data for UE operation. The 5G-GUTI identifier contains the 5G-S-TMSI identifier, which is used to identify the paging request for the UE.

[0163] Registration, connection and radio resource control management states

[0164] In 5GS, the UE maintains management states to enable communication with the core network. These management states include registration (RM), connection (CM), and radio resource control (RRC) management states. Management states are maintained in both the UE and the RAN / CN.

[0165] In order for the UE to use the services provided by the CN, the UE must register with the CN by performing an initial registration procedure. Once registered, the UE enters the RM-REGISTERED state from the RM-DEREGISTERED state, such as Figure 6 As shown in . The UE needs to perform periodic registration updates to maintain the RM-REGISTERED state with the network. When the UE is in the RM-DEREGISTERED state, it cannot access the services provided by the CN.

[0166] Figure 7 The connection management (CM) state shown in represents the NAS signaling connection between the UE and AMF over the N1 interface. This signaling connection allows the UE and CN to transfer information over the control plane for efficient communication within the 5G system.

[0167] Finally, the UE also maintains the RRC state with the RAN node, as described in TS 38.300 [4] as follows:

[0168] RRC_IDLE: The UE in this state performs PLMN selection, receives broadcast system information, and performs cell reselection. In addition, the UE can enter discontinuous reception (DRX) mode and monitor paging requests from 5GC.

[0169] RRC_INACTIVE: A UE in this state performs similar functions to RRC_IDLE, except for the fact that the paging request is initiated by the RAN node. In addition, the UE and the RAN node maintain context information that enables the UE to quickly transition to the RRC_CONNECTED state. When in this state, the control and user plane connections between the RAN node and the 5GC are established for the UE.

[0170] RRC_CONNECTED: When the UE is in this state, the transmission of unicast data to / from the UE is enabled. This is because a CP and UP are established between the RAN node and the CN for the UE, and other context information is retained between the UE and the RAN node to enable communication.

[0171] 5G paging mechanism

[0172] Paging refers to the following mechanism in 5GS where the core network or RAN notifies a UE in CM-IDLE or RRC_IDLE / RRC_INACTIVE state of pending data destined for the UE. TS 38.304[5] describes the use of discontinuous reception (DRX) by the UE when in RRC_IDLE and RRC_INACTIVE states to reduce power consumption during periods of inactivity. The UE monitors the Paging Occasions (PO) during DRX to be informed of activities in the CN that may require the UE to establish a connection. The UE makes calculations based on information provided by the system information received by the UE and the UE_ID to know when to monitor the paging occasions. The UE_ID is calculated from the UE's identifier (such as IMSI or 5G-S-TMSI) by applying a modulo operation on the identifier to 1024. On the network side, paging in 5G works similarly to LTE paging, such as Fig.23 as shown in .

[0173] Identifier

[0174] Section 5.9.4 of 23.501 describes the 5G Globally Unique Identifier (5G-GUTI).

[0175] The structure of 5G-GUTI is as follows:

[0176] <5G-GUTI>:= <guami><5G-TMSI>

[0177] Where GUAMI identifies the assigned AMF and 5G-TMSI uniquely identifies the UE within the AMF.

[0178] The Globally Unique AMF ID (GUAMI) shall be constructed as:

[0179] <guami> :＝ <mcc> <mnc><AMF Region ID><AMF Set ID><AMF Pointer>

[0180] Among them, the AMF Region ID identifies the region, the AMF Set ID uniquely identifies the AMF set within the AMF region, and the AMF Pointer uniquely identifies the AMF within the AMF set.

[0181] NOTE 1: AMF Region ID addresses the situation where there are more AMFs in the network than the AMF Set ID and AMF Pointer can support by enabling operators to reuse the same AMF Set ID and AMF Pointer in different regions.

[0182] NOTE 2: For detailed information on the structure of the GUAMI field, see TS 23.003

[19] .

[0183] 5G-S-TMSI is an abbreviated form of GUTI, which enables more efficient radio signaling procedures (e.g., during paging and service requests) and is defined as:

[0184] <5G-S-TMSI>:=<AMF Set ID><AMF Pointer> <5G-TMSI>

[0185] Slice-specific authentication and authorization

[0186] In Release 16 of the 5G system, 3GPP has agreed to add slice-specific authentication and authorization features. This process allows the network to initiate an EAP-based process to the UE when the UE attempts to register with certain slices (i.e., S-NSSAI). The EAP-based authentication process is based on the UE providing a user ID and associated network credentials in order to be authorized to access the slice. The new process is described in references [7] and [8] and is shown in Figure 8. Figure 8 is reproduced from reference [8].

[0187] LTE system architecture

[0188] Fig.19 The 3GPP EPS non-roaming system architecture is shown, where the user equipment (UE) communicates with the core network (CN) through the E-UTRAN 3202 to obtain Internet services or other operator services such as IMS. The E-UTRAN is a random access network (RAN) that is connected to the UE through the LTE-Uu interface. The UE accesses the CN via the E-UTRAN using NAS signaling through the S1-MME interface and sends and receives data via the E-UTRAN through the S1-U interface.

[0189] The following is a brief description of Fig.19 The following Network Functions (NF):

[0190] Mobility Management Entity (MME): The MME provides NAS signaling to the UE and authenticates and authorizes the UE to access the CN, while also managing UE mobility among the many functions it performs.

[0191] Home Subscriber Server (HSS) 2000: HSS 2000 provides authentication / authorization for UE and stores subscription information of UE.

[0192] Serving Gateway (S-GW) 2002: The S-GW 2002 serves as the mobility anchor point for the UE in the User Plane (UP), which routes and forwards traffic for the P-GW.

[0193] PDN Gateway (P-GW) 2004: P-GW 2004 allocates an IP address to the UE and provides the UE with access to a packet data network (such as the Internet).

[0194] • Policy and Charging Rules Function (PCRF) 2006: The policy and charging element of the core network.

[0195] LTE Attach Procedure

[0196] The UE performs an attach procedure in order to register with the core network and use services from the core network requiring registration. Figure 20 shows the attach procedure, and some notable steps related to the initial attach are highlighted below:

[0197] In step S2000, the UE sends an attach request to the CN via the eNodeB. In the request, the UE provides an identifier (IMSI), an attach type, UE core network capabilities, UE-specific DRX parameters, preferred network behavior and other message parameters, as indicated in [9].

[0198] In step S2002, the eNodeB selects an appropriate MME and forwards the request to the selected MME.

[0199] In steps S2004a and b, the MME performs authentication and NAS security setup to activate integrity protection and NAS ciphering, which is mandatory. The MME communicates with the HSS to complete this step. From this point on, NAS signaling is integrity and cipher protected.

[0200] In step S2006, the MME returns an Attach Accept to the Attach Request, which includes the GUTI, TAI list, session management request information, supported network behaviors, service gap time and other message parameters as indicated in [9].

[0201] In step S2008, the eNodeB returns an Attach Accept message to the UE, and the UE saves the message parameters for later use. There may also be associated RRC signaling.

[0202] In step S2010, the UE returns a direct transfer message including an attach complete message. The eNodeB forwards the attach complete message to the MME in step S2012.

[0203] EPS mobility management and connection management status

[0204] EPS Mobility Management (EMM) status Fig.21 . The UE is initially in the EMM-REGISTERED state, and after successfully attaching to the network, the UE enters the EMM-REGISTERED state. Once registered, the UE can use services provided by the network, such as connection to the Internet and making IMS calls. The UE remains in the EMM-REGISTERED state by performing a Tracking Area Update (TAU) procedure, and can enter the EMM-DEREGISTERED state by performing a Detach procedure.

[0205] EPS connection management state is Fig. 22 These states indicate the status of the NAS signaling connection between the UE and the core network. In ECM-IDLE, the UE has no NAS signaling connection and performs cell and PLMN selection. The transition from ECM-IDLE to ECM-CONNECTED state occurs for the following procedures: Attach Request, Tracking Area Update, Service Request, and Detach Request.

[0206] LTE Paging and Service Request

[0207] When UE 102 is in the ECM-IDLE state and data is available for UE 102 in the core network, MME 162 sends a paging request to UE 102, such as Fig.23 . UE 102 can then connect to the core network to receive data associated with the paging after performing the service request procedure. S-GW 2002 then stops paging UE 102 and downlink data is transmitted to UE 102 via the user plane. TS 36.304 [5] describes the calculation of the paging occasion of the UE in discontinuous reception (DRX) and how to calculate the paging occasion based on the UE's identifier. Based on the calculation, two UEs can have the same paging occasion and can monitor paging messages at the same time. The paging message will use the associated UE identifier to identify the recipient of the paging.

[0208] Problem Statement

[0209] A UE with multiple USIMs can be applied to various use cases that take advantage of registration with two or more operator networks. TR 22.834 [6] from the MUSIM study in the 3GPP SA1 working group highlights scenarios where there may be use cases involving multiple USIMs. The present disclosure focuses on the case where the UE is equipped with common radio and baseband components to support multiple USIMs. Therefore, the radio and baseband components cannot be dedicated to a single USIM. The present disclosure will also provide solutions for dual Rx, single Tx UEs that are also within the scope of the MUSIM study.

[0210] The MUSIM SA1 study highlighted potential requirements for multiple USIM UEs. Some of these requirements are:

[0211] Support UE with multiple USIM in 3GPP system

[0212] Support single Rx, single Tx and dual Rx, single Tx UE implementations

[0213] MUSIM UE allows users to configure preferences for services from multiple USIMs

[0214] · The 3GPP system should support MUSIM UEs with multiple USIMs from the same or different operators

[0215] The 3GPP system indicates the type of traffic to the MUSIM UE that triggered the paging procedure

[0216] · The 3GPP system should be able to suspend active communications and resume suspended communications with multiple USIM UEs

[0217] · The 3GPP system should minimize paging conflicts for paging with multiple USIM UEs

[0218] · 3GPP system should minimize signaling overhead by supporting multiple USIMs

[0219] MUSIM UE should be supported in both 5G and LTE systems

[0220] Note that the terms SIM and USIM (as used in TR 22.834 [6]) are used interchangeably in this disclosure. Furthermore, the term multi-SIM will be used to refer to multiple USIMs. Note also that the terms LTE and EPS are used interchangeably in this disclosure.

[0221] Use Case 1

[0222] A user is traveling abroad from the United States to Asia and has a UE that supports multiple USIMs. To reduce costs, the UE is implemented using common radio and baseband components, with the USIMs sharing access. Therefore, only one USIM can be active at any time. The user purchases a USIM to access cellular services when arriving at the destination country. The travel USIM provides local voice, text, and high-speed data services, while the home USIM is primarily used to provide voice and text that the user may wish to receive from family and friends while traveling.

[0223] Use Case 2

[0224] Another prominent use case that takes advantage of multiple USIMs centers around a user who has both business and personal subscriptions and wants to use both services on the same device. The user has a company-issued UE with a subscription to USIM1 from operator 1, while the user also has a personal subscription to USIM2 from operator 2. The user wants to be able to receive voice calls from either service and access data services based on the subscription to USIM1 or USIM2 depending on the time of day or application using the service.

[0225] question

[0226] As can be seen from the above use cases, a Multi-SIM UE utilizing common radio and baseband components must decide at any moment which SIM to serve. Current implementations of Multi-SIM UEs are proprietary and therefore implementations differ and UE behavior may differ. This difference in behavior can negatively impact the operation of the core network as many operations and algorithms are optimized based on the CN's knowledge of the UE behavior. Both 3GPP SA1 and SA2 working groups are currently investigating issues related to supporting UEs with multiple SIMs.

[0227] In these studies, it is proposed to standardize multi-SIM UEs and corresponding procedures to provide the core network with knowledge of the UE behavior and enable optimal operation of the UE to communicate with either network. These studies focus on UE implementations where common radio and baseband components are used to support multiple SIMs in the UE. Issues such as how the UE informs the CN of the multi-SIM capability, how the UE knows when to monitor paging occasions associated with paging of either SIM, how the UE switches operation from one SIM to another, how the UE informs the CN when switching the use of a SIM, how to minimize paging conflicts, what strategies the UE uses to provide service type prioritization between multiple SIMs, etc. remain to be determined. In addition, both LTE and 5G systems are expected to support multi-SIM UEs.

[0228] A major issue with UEs operating under multiple SIMs and using common radio and baseband components is the problem of a UE of a second SIM monitoring paging information while the UE of the second SIM is actively communicating with the first SIM. This is known as a paging conflict, where the paging occasions associated with multiple SIMs overlap in time. A UE with a single transceiver must decide to monitor a single paging channel over other paging channels [6]. This decision can cause the UE to miss a page if it does not have a paging request when monitoring the paging occasion of the inactive SIM.

[0229] Paging conflicts can occur in a multi-SIM UE for several scenarios. One scenario can be that the UE is not actively monitoring the paging occasions of the inactive SIM while the UE is connected to the network of the active SIM. Since the UEs share common baseband and radio components, the UE can be connected to one network at a time and monitor the paging occasions associated with the SIM of that network. If a page is sent for the SIM of another network, the UE cannot receive the page. This wastes radio resources at the RAN node that could be used for other purposes.

[0230] Another reason for paging conflicts is that the paging occasions of multiple SIMs overlap in time. Again, due to a single transceiver, the UE is able to monitor and process the paging occasions associated with one SIM. When the paging occasions overlap or are close together, the UE does not have enough time to switch the connection to the other network. This again wastes radio resources at the RAN node.

[0231] Even in the case where a multi-SIM UE is capable of monitoring paging occasions associated with multiple SIMs, the constant switching performed to achieve this will result in higher power consumption and reduced battery life of the UE. Furthermore, the UE may be switching connections for no purpose most of the time and if there is no data for the UE then the UE may not be paged. A side effect of frequent switching is that the UE may create a scenario for the occurrence of paging conflicts and the UE cannot enter a DRX cycle to conserve battery power.

[0232] Overview

[0233] Until now, multi-SIM UEs have been proprietary solutions implemented by device manufacturers without knowledge of the core network and outside the scope of 3GPP standards. The operation of cellular networks is designed so that the behavior of the various entities (UE, RAN and CN) is well defined and known among the various entities. Under different implementations of existing multi-SIM UEs, the different behaviors can negatively impact the operation of the network and may even degrade its performance. Therefore, the MUSIM study from 3GPP SA1 and SA2 working groups set out to define the architecture, interfaces and procedures to support UEs with multiple SIMs.

[0234] The requirements elaborated in the MUSIM study focus on UEs with common radio and baseband components that are shared by multiple SIMs installed in the UE and for dual Rx, single Tx UEs. The goal of the MUSIM work is then to provide the best possible service for the operation of each SIM for UEs with multiple SIMs. The focus of the study is how the UE can provide seamless paging monitoring for multiple SIMs through common radio and baseband components. A solution is proposed in this disclosure to address this problem and also for the case of dual Rx, single Tx UEs. Specifically, the solution includes:

[0235] Define enhancements to the UE registration and attach procedures to allow a multi-SIM UE to inform the core network that it is a multi-SIM device and provide information about the other SIMs installed in the UE

[0236] Define new registration management states, sub-states or operation modes for UE and CN to maintain UE registration status for each SIM

[0237] Define enhancements to the existing paging request mechanism to allow forwarding of paging requests from one PLMN to another to reach the UE

[0238] Define a SIM switching procedure where the UE can indicate to the CN that the UE is switching to another SIM and simultaneously update the UE's registration status in the CN and in the UE

[0239] Define the Inactivity Registration Timer Update procedure to be performed by the active PLMN to maintain the registration timer of the inactive SIM

[0240] Define a procedure whereby the UE may provide cell measurements obtained for an inactive PLMN when attempting to establish a connection with that PLMN after deciding to handover to that PLMN

[0241] Define a procedure whereby a UE can request a new temporary identifier whose paging occasions are aligned with or separated from paging occasions from another SIM

[0242] Define a procedure where the UE can request to suspend the registration timer, where the CN will also suspend paging to the UE

[0243] Define a procedure where the UE or CN can provide additional information about the paging process

[0244] Define new policies for 5G UE policy to allow configuration of multiple SIMs and also enable the user to initiate manual switching between SIMs through the GUI

[0245] Concept 1:

[0246] The UE informs the CN that it is a multi-SIM device and provides the CN with information about the other SIM:

[0247] The UE sends a request to the first PLMN to register the second SIM to the second PLMN

[0248] The UE includes an indication and an identifier of the second SIM to be registered with the second PLMN

[0249] The first PLMN forwards the request to the second PLMN

[0250] The second PLMN authenticates the UE's SIM credentials and provides the UE with a temporary identifier for the second SIM for the paging request

[0251] The UE and the second PLMN update the UE's registration status for the second SIM

[0252] Supporting features of Concept 1:

[0253] UE registers the first SIM with the first PLMN

[0254] The request is a partial register / attach or indirect register / attach request

[0255] The UE is registered on the first PLMN and requests to register on the second PLMN

[0256] ·Indication is multi-SIM indication

[0257] The identifier of the second SIM may be one of the following: SUPI (e.g. IMSI), GUTI, 5G-S-TMSI or SUCI

[0258] The temporary identifier assigned to the second SIM may be 5G-GUTI, GUTI, 5G-TMSI, TMSI or 5G-S-TMSI

[0259] The first PLMN includes an identifier of a network node supporting multi-SIM operation and an identifier of the first SIM that has been authenticated by the first PLMN

[0260] After successfully registering to the second PLMN, the UE's registration status is RM-INACTIVE or EMM-INACTIVE

[0261] The first PLMN may assign a second temporary identifier to the second SIM and save the UE's registration status for the second SIM

[0262] UE provides multi-SIM assistance information to CN; multi-SIM assistance information may consist of one or more of the following: paging criteria, restricted paging area, paging opportunity separation, number of missed pages before notification, proposed temporary identifier

[0263] Concept 2:

[0264] The first PLMN forwards the paging request to the UE via the second PLMN:

[0265] The first PLMN receives data associated with the first SIM

[0266] The first PLMN forwards the paging request to the second PLMN, where the paging request includes a temporary ID associated with the first SIM

[0267] The second PLMN sends a paging request to the UE at the paging occasion that the UE is monitoring

[0268] UE retrieves paging information and receives a temporary identifier associated with the first SIM Supported features for Concept 2:

[0269] UE supports multi-SIM operation

[0270] UE is registered to both the first and second PLMN

[0271] UE has inactive registration on the first PLMN

[0272] UE has active registration on the second PLMN

[0273] A paging request is sent from the first PLMN to the second PLMN in an encrypted NAS container

[0274] The paging opportunity is calculated based on the temporary identifier of SIM1

[0275] The paging opportunity is calculated based on the temporary identifier of SIM2

[0276] • The paging information includes the service class to which the paging is directed and may be classified as a voice call, SMS message or other data (eg, application data), control plane signaling, emergency message, emergency call back, mobile terminated exception data, and the like.

[0277] The paging information includes the application ID and PDU session ID associated with the paging.

[0278] UE sends a response to the first PLMN via the second PLMN

[0279] Concept 3:

[0280] The UE performs the SIM switching process:

[0281] The UE receives paging information for data associated with the second SIM while connected to the first PLMN

[0282] The UE decides to switch to the second PLMN to retrieve data based on the service type prioritization indicator provided in the paging message

[0283] UE notifies the first PLMN to suspend the registration status of the first SIM

[0284] The UE and the first PLMN update the registration status of the first SIM on the UE and the first PLMN

[0285] The UE attempts to establish communication with the second PLMN for the second SIM

[0286] Supporting features of Concept 3:

[0287] Paging information provision may include service type prioritization of service class, application ID associated with the data the UE is paging, and PDU session ID

[0288] UE checks service type prioritization according to internal policy and finds a match

[0289] UE sends a registration update request with the registration type set to SIM switch

[0290] The first PLMN activates paging request forwarding for the first SIM

[0291] The registration status for the first SIM is set to RM-INACTIVE or EMM-INACTIVE in the UE and the first PLMN

[0292] The first PLMN sends a response to the second PLMN indicating that the UE has received the paging request

[0293] Establishing communication with the second PLMN includes sending a registration update request to include the SIM switch registration type

[0294] Concept 4:

[0295] The UE updates the registration timer in the second PLMN through the first PLMN:

[0296] The UE sends a request to the first PLMN to update the registration timer of the second SIM on the second PLMN

[0297] The first PLMN forwards the request to the second PLMN

[0298] The second PLMN updates the registration timer for the second SIM in the second PLMN

[0299] The second PLMN returns a response to the first PLMN

[0300] The first PLMN forwards the response to the UE

[0301] Supporting features of Concept 4:

[0302] The request can be a registration update, tracking area update, or inactivity registration timer update

[0303] The request includes a temporary identifier associated with the second SIM

[0304] The response may include the status of the registration update request, the new value of the registration timer, or the updated TAI list

[0305] The response may include an indication that the registration status for the second SIM is no longer valid

[0306] The second PLMN may allocate a new temporary identifier for the second SIM and include it in the response to the UE

[0307] Concept 5:

[0308] After the SIM switching process, the UE collects cell measurement information when connected to the second PLMN and provides the measurement results directly to the second PLMN after the connection, or if the connection is unsuccessful, then provides the measurement results to the second PLMN through the first PLMN:

[0309] Collect cell measurements when the UE attempts to connect to a second PLMN after disconnecting from the first PLMN

[0310] UE provides cell measurement results to the RAN node after successfully connecting to the second PLMN

[0311] UE connects to the first PLMN after a failed attempt to connect to the second PLMN and includes the collected measurements and cause code

[0312] The first PLMN forwards the measurement result and reason code to the second PLMN

[0313] Supporting features of Concept 5:

[0314] If the UE successfully connects to the second PLMN, the UE formats the cell measurement results as a Minimized Drive Test Report to the RAN node of the second PLMN

[0315] The cell measurement result indicates the signal strength of the cell belonging to the second PLMN

[0316] Cell measurement results include the location and time of measurement

[0317] Cell measurement results can be queued by the UE and sent to the RAN node upon successful future connection

[0318] UE saves cell measurement results and cause code after unsuccessful connection to second PLMN

[0319] The cause code may be received from the second PLMN or generated by the UE

[0320] The reason code may indicate that the RAN node is overloaded and is not accepting new registrations

[0321] The reason code may indicate that the mobility management node is overloaded and is not accepting new registrations

[0322] The cause code may indicate that the signal strength of the cell is insufficient to maintain a connection to the second PLMN

[0323] The cause code may indicate that there is no available cell to establish a connection with the second PLMN

[0324] Concept 6:

[0325] The UE requests a new temporary identifier whose paging occasion is aligned with or separated from the paging occasion associated with another SIM:

[0326] The UE is registered to the first PLMN and receives a temporary identifier with an associated paging occasion for the first SIM

[0327] The UE is registered to the second PLMN and receives a temporary identifier with an associated paging occasion for the second SIM

[0328] The UE determines the possibility of a paging conflict between the paging occasions of the two SIMs

[0329] The UE requests a new temporary identifier whose paging occasion is different from the previous paging occasion

[0330] Supporting features of Concept 6:

[0331] The request can be, for example, one of an initial registration, mobile registration update, periodic registration update, attach or tracking area update request

[0332] The UE can provide parameters in the request to assist the network in allocating a new temporary identifier

[0333] New parameters can be, for example: paging criteria, restricted paging area, paging occasion separation, multi-SIM indicator, temporary identifier or multiple paging occasions

[0334] The network may assign a temporary identifier whose paging occasion is, for example, the same as, very close to, far from, or different from an existing paging occasion

[0335] The network can assign multiple temporary identifiers corresponding to multiple paging occasions to the UE Concept 7:

[0336] The UE requests to suspend the registration timer associated with the SIM:

[0337] UE registers to PLMN and PLMN starts registration timer

[0338] UE sends a request to activate the registration suspension timer

[0339] CN suspends the registration timer and starts the registration suspension timer

[0340] CN provides a response that the registration pending timer is active

[0341] Supporting features of Idea 7:

[0342] The request can be, for example, one of an initial registration, mobile registration update, periodic registration update, attach or tracking area update request

[0343] UE can provide expiration value for registration suspension timer

[0344] When the registration suspension timer is running, the UE can request the CN to queue any downlink data for the UE

[0345] The CN maintains context for the UE, such as registration status, security context, PDU session, etc.

[0346] CN can return the new value of the expiration time of the registration pending timer

[0347] The CN may provide an indication that it will queue downlink data for the UE

[0348] Concept 8:

[0349] UE or CN provides information about problems with the paging procedure:

[0350] UE is registered with multiple SIM cards

[0351] UE is receiving data for the first SIM

[0352] UE receives paging for the second SIM

[0353] UE or CN notifies the other party of the paging process problem

[0354] Supporting features of Idea 8:

[0355] Notification can be a request sent by the UE

[0356] The request can be one of the following, for example, Mobile Registration Update, Periodic Registration Update, Tracking Area Update, or Service Request

[0357] UE can provide an instruction to CN to stop paging UE

[0358] Notification can be a response sent by CN

[0359] The response may include, for example, an indication informing the UE that it missed a previously sent page, the time of that page, the tracking or registration area to which the page was sent, and other information about the page, such as service class, phone number, PDU session ID, and application ID

[0360] Detailed Description

[0361] As highlighted in the MUSIM study [6], current multi-SIM UE implementations with common radio and baseband components present a number of issues with different UE behaviors that may degrade network performance. To address such issues, a more integrated solution is proposed, where the UE communicates its support for multi-SIM functionality to the core network using a newly proposed registration request, and the network enhances the paging mechanism by providing service prioritization information in the paging message and enabling paging request forwarding to minimize the UE switching cycle between SIMs. These enhancements will enable the UE to receive prioritization information for paging for multiple SIMs by monitoring only the paging occasions calculated for the active SIM, rather than requiring the UE to switch operations to monitor the paging occasions for each SIM. In addition, the network is made aware of the UE's new registration state, sub-state, or operating mode through a new SIM switching procedure and enhancements to the UE registration state. This enhancement will enable entities within the cellular system to be aware of the operation of a multi-SIM UE. The solution proposed in this paper is designed based on the following assumptions:

[0362] 1. UE implementations with multiple SIMs sharing common radio and baseband components; some solutions will be presented to address dual Rx, single Tx capable UEs

[0363] 2. Multiple SIMs from the same or different PLMNs (PLMN refers to the networks of different operators, also known as mobile network operators or MNOs)

[0364] 3. If necessary, PLMNs can have roaming agreements with each other and support SIM authentication as proposed in this article

[0365] 4. Establish security support for multi-SIM operation between UE and core network

[0366] 5. Both the UE and the core network support the multi-SIM capability proposed in this paper

[0367] However, there may be situations where there is no coordination between mobile network operators or MNOs. In these situations, an alternative solution that does not require coordination between MNOs will be presented, where the UE can request different temporary identifiers from the network that correspond to paging occasions that are different from the currently assigned PO. This and other solutions will also be presented to address situations without MNO coordination. Note that certain aspects of the solutions associated with MNO coordination can also be used in scenarios without MNO coordination. For example, the core network assigning temporary identifiers associated with the same PO to multiple SIMs can be used in situations without MNO coordination. This can be used in intra-MNO situations where multiple SIMs belong to the same MNO.

[0368] Both 5GS and LTE systems require solutions to support multi-SIM UEs. Therefore, the present disclosure applies the proposed solution to both 5GS and LTE systems. For the case where a solution is shown for only one system, the solution can also be easily applied to the other system.

[0369] Fig. 9 The main process of the proposed solution for a UE with two SIMs is shown, but the solution can be extended to UEs with more than two SIMs. The figure shows that the UE uses different SIMs, SIM1 and SIM2, registered to two PLMNs. The UE has service subscriptions for both SIM1 and SIM2, and mainly uses SIM1 to communicate with PLMN1, while registering SIM2 with PLMN2 and requesting PLMN2 to forward paging requests for SIM2 to PLMN1 for further processing. Therefore, the UE will only need to monitor the paging occasions associated with SIM1 on PLMN1 to receive paging requests for both SIM1 and SIM2. Similarly, when the UE is communicating with PLMN2, the UE can receive paging requests for both SIM1 and SIM2 by monitoring the paging occasions associated with SIM2 on PLMN2 only. Note that the UE monitors the paging occasions only on the active PLMN, while being able to receive paging for multiple SIMs, for example, paging for the active SIM and for the inactive SIM. The mutual registration of SIMs between PLMNs and the paging request forwarding feature allows the UE to operate in such a way that the power consumption required is reduced and still be able to receive pages for multiple SIMs.

[0370] Fig. 9 Two different registration procedures are proposed in to link SIM1 and SIM2 in the corresponding PLMN: partial registration and indirect registration procedures. These registration procedures enable all paging requests, whether for SIM1 or SIM2, to be received by the UE on the PLMN where the UE actively registers. In other words, paging requests for inactive SIMs will be received at the paging occasions of the active SIMs. This solution solves the paging conflict problem described previously, because the UE can receive paging for multiple SIMs without frequently switching connections between different PLMNs.

[0371] The UE uses the SIM Switching procedure to inform the active PLMN to suspend the UE's registration state so that the UE can establish communication with the inactive PLMN to complete processing of paging requests or use of subscription services associated with the inactive SIM. Using this procedure, the UE is able to switch between subscription services provided by the two SIMs and still receive paging requests for either SIM, regardless of which PLMN the UE is actively registered to at any time. This procedure informs the core network that the UE intends to switch connections between PLMNs, thereby resolving the problem of the network not being aware of what the UE is doing in multiple SIM applications.

[0372] Step S900: The UE registers with PLMN1 via SIM1 and establishes a PDU session on PLMN1. The UE may provide a multi-SIM indication to PLMN1 to inform PLMN1 that the UE is a multi-SIM device and may provide a UE identifier (e.g., SUPI (e.g., IMSI), GUTI, 5G-S-TMSI, or SUCI) for use by SIM2 in the partial registration process shown in step S902b. Including the multi-SIM indication and (one or more) UE identifiers supports the case where the UE has two SIMs installed before performing the UE initial registration process. This step may be triggered by inserting a second SIM, downloading a second SIM profile to the eSIM, an indication from the GUI, or by a power cycle event.

[0373] Step S909: Alternatively, the UE may separately inform PLMN1 that it is a multi-SIM device and provide (one or more) UE identifiers to PLMN1 for SIM2 to initiate the partial registration process shown in step S902b. Note that steps S900 and S902a are different methods of initiating the partial registration process. For example, if the two SIMs are installed at different times, then step S902a can be performed by the UE. In step S902b, PLMN1 and PLMN2 perform partial registration for SIM2. The AMF in PLMN1 may contact the AUSF and / or UDM in PLMN2 and provide the following information to link the two SIMs together: an indication of requesting partial registration, an indication that the UE is a multi-SIM device, UE identifiers of SIM1 and SIM2, an indication that SIM1 has been authenticated and registered with PLMN1, multi-SIM auxiliary information, etc. PLMN2 may save this information in UDM2, and PLMN1 may save the information returned to the UE after successful registration (e.g., a temporary identifier) ​​and the same information in UDM1. In this case, (one or more) UE identifiers may refer to permanent and temporary identifiers used to associate to the SIM. Multi-SIM assistance information may be provided to assist the network in enhancing the paging procedure for Multi-SIM UEs.

[0374] Step S904: As an alternative to partial registration, the UE may perform an indirect registration for SIM2 with PLMN2 via PLMN1 to establish a registration state with PLMN2. This may be performed in either the control plane or the user plane. If successful, the results of the indirect registration are similar to those of the UE establishing a registration state with the core network as outlined in TS 23.502 [2] General Registration, i.e., assignment of temporary identifiers, network slices, update timers, DRX parameters, etc. However, certain enhancements set out below for multi-SIM operation apply to indirect registration. This registration procedure places the UE in the RM-INACTIVE state and may provide the UE with a different set of temporary identifiers than the set of temporary identifiers returned from the general registration procedure. The procedure may link SIM1 and SIM2 together on PLMN2, similar to the link established by partial registration, to enable paging request forwarding. Similar to partial registration, indirect registration may be initiated as part of general registration or independently as a separate registration step (i.e., similar to steps S900 and S902a, but for indirect registration).

[0375] Step S906: Later, the UE receives a paging request for SIM2 from PLMN1. The paging request originates from PLMN2, which forwards the request to PLMN1. Note that detailed paging information can be sent from PLMN2 to PLMN1 within an encrypted NAS container to protect the privacy of the UE. The paging request is discovered at a paging opportunity associated with SIM1, and when the UE reads the paging channel, the paging information is associated with SIM2. The paging information may contain a service type prioritization for paging to enable the UE to decide whether to continue processing the paging request. In addition, more detailed paging information can be obtained by the UE performing a service request procedure and receiving an encrypted NAS container with service prioritization information. Alternatively, the forwarded paging request can be received by the UE as a NAS notification over the user plane of the network.

[0376] Step S910: The UE notifies PLMN1 that it needs to perform a "SIM switch" procedure to PLMN2. Since PLMN1 knows SIM2 and has linkage information for SIM2, PLMN1 assists the UE in performing the SIM switch. This procedure changes the UE's registration state on PLMN1 to RM-INACTIVE, which is a new registration state, sub-state, or operation mode of the RM-REGISTERED state proposed by this solution to indicate that the UE's registration on PLMN1 is temporarily suspended. The UE context in PLMN1 is retained for SIM1 to allow the UE to switch to using SIM2 on PLMN2. Using the saved context, the UE is able to switch back to PLMN1 and quickly resume operation. Other alternatives to the SIM switch procedure are also proposed, in which a multi-SIM UE can notify the network to suspend the registration state of one SIM so that the UE can communicate with another SIM. During the suspension of the registration state, the paging mechanism can be modified so that the network forwards paging requests, filters paging messages to the UE, buffers downlink data, etc.

[0377] Step S912: The UE performs a periodic registration update procedure to change its registration state for SIM2 from RM-INACTIVE to RM-REGISTERED. Note that before performing a periodic registration update, the UE may first need to perform procedures involving cell search, PLMN selection, establishing an RRC connection with RAN2, etc. After receiving the registration accept response, the UE may then perform a service request or PDU session establishment procedure to retrieve data associated with the paging request. The UE may perform a service request as an alternative to a periodic registration update.

[0378] Step S914: After the UE completes the session to retrieve data associated with the paging request, the UE may suspend the registration state of SIM2 by performing a SIM switching procedure, as shown in step S1914a, and then reactivate the registration state for SIM1, as shown in step S1914b.

[0379] Fig. 9 Other enhancements not shown in the are the Inactive Registration Timer Update procedure, where the UE can request an update of the registration timer of an inactive SIM through the active PLMN. This procedure provides the inactive PLMN with an update that the UE is still connected to the active PLMN and can therefore receive forwarded paging requests. Another enhancement allows the UE to collect cell measurement information when attempting to establish a connection with the PLMN after a SIM switching procedure. These measurements can be provided to the PLMN after a successful connection establishment, or through another PLMN if the connection is unsuccessful. The network operator can use the cell measurement results to determine the network coverage and improve the cellular coverage of the system if necessary. Other enhancements are also proposed for multi-SIM operation in uncoordinated MNOs.

[0380] When discussing multi-SIM operation, it is important to define technical terms used to clearly distinguish which SIM / PLMN the UE is actively using for communication at any moment in time. The terms primary and secondary refer to the SIM prioritization outlined by the UE policy or by the user through the GUI. These terms indicate which SIM (primary) in the UE has priority over the other SIMs (secondary). The UE will typically use the primary SIM most of the time. The terms "active" or "inactive" refer to the SIM / PLMN with which the UE is currently communicating. In other words, the UE maintains a connection to the "active" PLMN and has no connection to the "inactive" PLMN. Fig. 9 Take, for example, the use of the terminology.

[0381] Primary SIM = SIM1

[0382] Secondary SIM = SIM2

[0383] Active SIM / PLMN = SIM1 / PLMN1 (for steps 1-5); SIM2 / PLMN2 (for steps 6-7)

[0384] Inactive SIM / PLMN = SIM2 / PLMN2 (for steps 1-5); SIM1 / PLMN1 (for steps 6-7)

[0385] The terms “primary” and “secondary” may also apply to the PLMNs when it is not initially known which PLMN is active and which PLMN is inactive, for example, before the UE registers with the PLMNs.

[0386] The following solutions apply to the case where the SIMs are from different operators. However, these solutions can be adapted to support SIMs from the same operator. For example, the registration procedures will apply to the same PLMN and will not rely on roaming agreements between PLMNs. The procedures will still link the paging requests of SIM1 and SIM2 together, and the UE will receive paging requests at the paging time of the active SIM. Whether the SIMs are from the same or different operators, the registration state transitions and SIM switching procedures remain the same. In the case of the same operator, the UE does not need to switch connections between PLMNs after performing the SIM switching procedure.

[0387] Note that the following solutions are described in the context of 5GS, but these solutions can also be applied to EPS. For example, the proposed registration process can be performed with the MME in EPS, and the function of the MME in EPS is similar to that of the AMF in 5GS. It should be noted that in 5GS, NAS messaging is between the UE and the AMF; in EPS, NAS messaging is between the UE and the MME. In EPS, the attachment process and the HSS perform functions similar to the general registration process and UDM in 5GS, respectively. The RAN nodes are eNodeBs for EPS and gNodeBs for 5GS. Similarly, the RM-INACTIVE state proposed in this article for 5GS can be a new state, such as EMM-INACTIVE in EPS. The SIM switching process can also be performed in EPS and 5GS, and multi-SIM policies or information elements can be combined into the two systems. The solution in this disclosure describes how to pass policies from the PCF to the UE via NAS messaging. In EPS, policies can be passed to the UE from the ANDSF server via an IP-based process or via information elements sent in NAS messages. When it is applied to the EPS system, an embodiment will be provided to illustrate some of these enhancements.

[0388] Different aspects of the LTE system are enhanced to support the use of multi-SIM UEs. The first aspect applies to the attach procedure that the UE performs to register with the core network. These enhancements to the attach procedure are proposed: partial attach, indirect attach and MUSIM attach. These attach procedure enhancements relate to the registration of multiple SIMs for use within the UE. Partial attach registers the secondary SIM with the HSS of the corresponding PLMN of the secondary SIM, which will trigger the forwarding of paging requests originating from the HSS. On the other hand, indirect attach registers the secondary SIM with the MME of the corresponding PLMN and a default bearer can be established for the PDN connectivity that always occurs. Finally, the MUSIM attach enhancement allows the UE to indicate to the core network in a single request that an attach procedure needs to be performed for multiple SIMs, which triggers the performance of a partial attach or indirect attach procedure for the secondary SIM.

[0389] Furthermore, it is proposed to add a new LTE EMM state in the UE and MME to support a new registration operation mode enabled for UEs with multiple SIMs: EMM-INACTIVE. This new registration state indicates that the UE operating with the secondary SIM is registered to the corresponding PLMN, but it is not actively connected to that PLMN. In addition, due to the above-mentioned enhancements to the attach procedure, paging request forwarding is enabled. Paging request forwarding refers to the process by which the inactive PLMN forwards a paging request for an inactive SIM to the active PLMN to page the UE. All of these LTE system enhancements are similar to the 5G enhancements and will be described in more detail below.

[0390] Note that although the present disclosure refers to EMM-INACTIVE as a new state in the EMM state model, due to current LTE deployments, it may be more feasible to instead be a sub-state or operating mode within the EMM-REGISTERED state. This sub-state or operating mode may be referred to as an "inactive registration" sub-state or mode of EMM-REGISTERED. It is also noted that the UE and MME may maintain separate EMM and ECM states for each SIM.

[0391] Once the registration status is established for each SIM in a multi-SIM UE, the function of paging request forwarding is enabled to eliminate the occurrence of paging conflicts. When data is available for the inactive SIM, the corresponding PLMN forwards the paging request to the UE via the active PLMN. Within the active PLMN, the paging occasions are calculated so that the UE will only need to monitor one paging occasion while being able to receive paging requests for multiple SIMs. As described below, paging information can be sent via NAS notification in some cases.

[0392] Multi-SIM Registration Process

[0393] The E-UTRAN cell may broadcast in a system information broadcast whether the UE can connect to an MME that supports partial and / or indirect attach. The UE may check whether the E-UTRAN cell is broadcasting this indication before attempting to perform a partial and / or indirect attach with the network via the E-UTRAN cell.

[0394] NOTE: The same check operation can be performed in the 5G system. In other words, the NR cell can broadcast in the system information broadcast whether it can connect to an AMF that supports partial and / or indirect connection. The UE can check whether the NR cell is broadcasting this indication before attempting to perform a partial and / or indirect connection with the network via the NR cell.

[0395] As mentioned earlier, two registration procedures are proposed in the present disclosure to support multi-SIM operation in 5GS. The registration procedures enable the UE to receive services from the 5G network. The partial registration is invoked by the UE to register the SIM with the secondary PLMN via the primary PLMN. By performing this registration, when the UE is not actively registered with the secondary PLMN, the UE notifies the secondary PLMN to forward all paging requests to the UE through the primary PLMN. On the other hand, the indirect registration performs a complete registration as outlined in the general registration procedure in TS23.502[2] to the secondary PLMN through the primary PLMN. When the UE is not actively communicating with the secondary PLMN, the indirect registration procedure also notifies the secondary PLMN to forward all paging requests to the primary PLMN. In both registration procedures, the RM state of the UE with the secondary PLMN changes from RM-DEREGISTERED to RM-INACTIVE. For indirect registration, an AMF is assigned to serve the UE, which is different from the partial registration in which no AMF is assigned to serve the UE.

[0396] Similar to the 5G registration process, the UE must perform an attachment process with the core network in the LTE system in order to be able to receive services from the network. The attachment process registers the UE with the core network by authenticating the UE and establishing a context for the UE to communicate securely with the network. For the case of multiple SIMs, an enhanced attachment process is proposed to support registration of multiple SIMs. This article describes enhancements: 1) partial attachment, 2) indirect attachment, and 3) MUSIM attachment. MUSIM attachment combines multiple attachment requests (for example, an attachment request for the primary SIM and one or more attachment requests for the secondary SIM) into a single request. The MUSIM attachment process can also be applied to the 5G system in a similar manner.

[0397] For all described registration and attach procedures, the UE may include multi-SIM assistance information in the corresponding request messages, such as information configured at the UE (e.g., by the user). The network may use the assistance information to enhance existing paging mechanisms for multi-SIM operation. For example, the assistance information may provide prioritization information that informs whether and when to page the UE when downlink data is available for a particular SIM. In addition, the assistance information may provide information about how the network may assign identifiers corresponding to paging occasions so that they avoid paging conflicts for multiple SIMs. The multi-SIM assistance information will be described in more detail below.

[0398] Partial Registration

[0399] The UE performs partial registration primarily to configure the secondary PLMN so that all paging requests are forwarded to the UE via the primary PLMN whenever the RM state of the UE with the secondary PLMN is RM-INACTIVE. This process enables the UE to receive all paging requests (whether the paging request is for SIM1 or SIM2) at the paging occasions associated with the active SIM, regardless of the PLMN with which the UE is actively communicating. As a result, the UE will not need to switch network connections between SIMs to receive paging requests. In fact, this process will guarantee that the UE receives all paging requests, whereas the process of having the UE switch between SIMs would result in missed paging requests if the switching timing does not coincide with the timing of the paging request. Note that the partial registration enhancement enables the paging request forwarding functionality to originate from the UDM, which is a new functionality added to the UDM.

[0400] Fig.10 The UE is shown initiating a partial registration procedure for SIM2 via PLMN1. The figure shows two situations where partial registration of SIM2 can be performed: 1. When two SIMs are installed together and the partial registration request is part of the initial registration request (this is called MUSIM registration), or 2. When SIM2 is installed after SIM1 is installed and the UE has performed an initial registration on SIM1.

[0401] Step S1002: The UE registers SIM1 with PLMN1, where the registration type is initial registration. At this point, only SIM1 is installed in the UE. However, if SIM1 and SIM2 are installed at the same time, then when the UE registers SIM1 with PLMN1, the UE may include a multi-SIM indication with (one or more) appropriate SIM2 identifiers (e.g., SUPI (e.g., IMSI), GUTI, 5G-S-TMSI, or SUCI). In this case, it is proposed to integrate the partial registration request as part of the universal registration procedure performed for SIM1 (the universal registration procedure described in TS23.502 [2]). This process may be referred to as MUSIM registration. The addition to the initial registration request will include a multi-SIM indication, a partial registration indicator and one or more SIM2 identifiers, as indicated above. The multi-SIM indicator may be encoded as an option in the preferred network behavior parameter, or it may be a separate indicator and the partial registration indicator may be combined in the registration type parameter. The message may also indicate which SIM is the primary SIM and which SIMs are secondary SIMs and should be used to register to the inactive PLMN. For this case, the process jumps to step S1006.

[0402] Step S1004: At some time after the UE successfully registers SIM1 with PLMN1 and SIM2 is installed in the UE, a partial registration request may be initiated by the UE to inform PLMN1 that the UE is a multi-SIM device and includes a multi-SIM indication and (one or more) SIM2 identifiers. The registration type for this request may be a partial registration or a partial registration indicator may be provided. At this time, the RM state for SIM1 is RM-REGISTERED, and the RM state for SIM2 (under PLMN2) is RM-DEREGISTERED. (One or more) SIM2 identifiers will be used by PLMN2 to authenticate SIM2 to the UE and may include: SUPI (e.g., IMSI), GUTI, 5G-S-TMSI or SUCI. The partial registration request may be a newly defined procedure, or it may be combined as part of a general registration procedure. The multi-SIM indicator may be encoded as an option in the preferred network behavior parameter, or it may be a separate indicator. The multi-SIM indicator may be used by a network entity to check and select an appropriate network entity that supports multi-SIM operation during the registration process.

[0403] Step S1006: RAN1 forwards the partial registration request to AMF1 via the N2 interface previously established for SIM1. In the case of MUSIM registration, RAN1 selects AMF1 to process the request.

[0404] Step S1008: Due to the presence of the multi-SIM indication and / or the fact that the UE 102 is requesting a partial registration, the AMF 1904 selects AUSF2 908 and requests AUSF2 908 to authenticate the UE 102 for SIM2 by sending (one or more) SIM2 identifiers together with the multi-SIM indication and the partial registration indicator to AUSF2 908. If the request is a MUSIM registration, then the AMF 1904 may first register SIM1 and then send a partial registration request for SIM2 later. Note that it is assumed that a roaming agreement between PLMN1 and PLMN2 is in place and the AMF within each PLMN may be configured with the contact information of the AUSF in the other PLMN to forward the partial registration request to it. It is also assumed that the communication between AMF1 904 and AUSF2 908 is secure, for example, via the N32 interface through SEPPS of the corresponding PLMN.

[0405] Step S1010: AMF1 904 forwards the partial registration request to AUSF2 908 and may include: a registration type set to partial registration or including a partial registration indicator, a multi-SIM indication which may be encoded as an option in the preferred network behavior, (one or more) SIM2 identifiers, AMF1 ID and UE ID to indicate that the UE with SIM1 has authenticated with PLMN1, context information of the AMF in PLMN1 to which PLMN2 may forward future paging requests for SIM2, etc. Note that in step S1002, the registration type was set to initial registration for SIM1; however, this registration request is for SIM2, so the registration type for this request to AUSF2 908 is changed from initial registration to partial registration. Alternatively, the registration type may be set to initial registration and a partial registration indicator may be provided in the request. The registration type from step S1002 may also be encoded as initial registration with partial registration.

[0406] Step S1012: AUSF2 908 performs authentication of the UE for SIM2 and may create or update subscription information in UDM2 910. UDM2 910 may provide a temporary identifier to the UE 102 for SIM2, which will be used to indicate when a paging request is targeted at SIM2. In addition, the RM state for SIM2 will be updated to RM-INACTIVE to enable forwarding of paging requests to the UE via PLMN1. The RM state in this case may be an indication in the subscription data stored in the UDM to indicate that paging request forwarding is enabled.

[0407] Step S1014: After AUSF2 authenticates the UE for SIM2, a partial registration accept message is returned to AMF1. The partial registration accept message may be a modified registration accept message. AUSF2 may include the following information in the accept message: an indication of successful authentication of SIM2, a temporary identifier assigned to the UE by UDM2 for SIM2, an indication that the RM state of the UE for SIM2 has changed from RM-DEREGISTERED to RM-INACTIVE, a confirmation of support for receiving paging requests forwarded by PLMN1 for SIM1, contact information for MME to receive paging requests from PLMN1, and a registration timer for SIM2. When the UE actively registers to PLMN1, the UE's temporary identifier will be used to page the UE whenever there is paging for SIM2. In addition, the contact information of the default AMF may be included in the accept message to inform AMF1 that future paging requests may originate from the default AMF instead of from the UDM.

[0408] Step S1016: AMF1 forwards a partial registration accept message to the UE via RAN1 and includes the information returned from AUSF2 to AMF1. The accept message may include an indication that SIM2 has been successfully authenticated, a temporary identifier assigned to the UE by UDM2 for SIM2, an indication that the RM state of the UE for SIM2 has changed from RM-DEREGISTERED to RM-INACTIVE, and a registration timer for SIM2. When the UE actively registers to PLMN1, the UE's temporary identifier will be used to page the UE from PLMN2 using the paging request forwarding function whenever there is paging for SIM2. Alternatively, AMF1 may assign a separate temporary identifier to SIM2, which may be used instead to page the UE in PLMN1. The assignment of this temporary identifier may cause the associated paging occasion to overlap with the paging occasion associated with SIM1. Therefore, the UE will only need to monitor one paging occasion in order to receive paging for SIM1 and SIM2. AMF1 may alternatively assign the same temporary identifier to all SIMs associated with the UE, while maintaining the fact that the UE only needs to monitor one paging occasion and can receive paging for all SIMs. The UE's RM state for each SIM is updated in the UE and should match the state in AMF1: RM-REGISTERED for SIM1 and RM-INACTIVE for SIM2.

[0409] This process proposes that the UDM assigns a temporary identifier to the UE and provides the temporary identifier to the UE. This temporary identifier can be a new type of 5G-GUTI. This 5G-GUTI can be formatted in a way that is compatible with the existing 5G-GUTI format. For example:

[0410] GUAMI can include only <mcc>and <mnc>, so that it can be parsed as a UDM / UDR. GUAMI does not include<AMFRegion ID><AMF Set ID> and<AMF Pointer> The fact that may indicate that 5G-GUTI is assigned by UDM.

[0411] The 5G-TMSI in the 5G-GUTI may be a temporary identifier assigned to the UE by the UDM, or it may be a SUCI or GPSI. This temporary identifier may be included in a paging message so that the UE can detect that it is being paged for the associated SIM.

[0412] Partial Registration Alternative

[0413] This section proposes an alternative procedure for the UE to perform a partial registration, such as Fig.11 as shown in .

[0414] Step S1102: The UE registers SIM1 with PLMN1, where the registration type is initial registration. At this point, only SIM1 is installed in the UE. However, if SIM1 and SIM2 are installed at the same time, then when the UE registers SIM1 with PLMN1, the UE may include a multi-SIM indication, a partial registration indicator and (one or more) appropriate SIM2 identifiers (e.g., SUPI (e.g., IMSI), GUTI, 5G-S-TMSI or SUCI). In this case, it is proposed to integrate the partial registration request as part of the universal registration procedure performed for SIM1 (the universal registration procedure described in TS 23.502 [2]). This process may be referred to as MUSIM registration. The addition to the initial registration request will include a multi-SIM indication, a partial registration indicator and one or more SIM2 identifiers, as indicated above. The multi-SIM indicator may be encoded as an option in the preferred network behavior parameter, or it may be a separate indicator and the partial registration indicator may be combined in the registration type parameter. The message may also indicate which SIM is the primary SIM and which SIMs are secondary SIMs and should be used to register to the inactive PLMN. In this case, the process jumps to step S1106.

[0415] Step S1104: At some time after the UE successfully registers SIM1 with PLMN1 and SIM2 is installed in the UE, a partial registration request may be initiated by the UE to inform PLMN1 that the UE is a multi-SIM device and includes a multi-SIM indication and (one or more) SIM2 identifiers. The registration type for this request may be a partial registration or a partial registration indicator may be provided. At this time, the RM state for SIM1 is RM-REGISTERED, while the RM state for SIM2 (under PLMN2) is RM-DEREGISTERED. (One or more) SIM2 identifiers will be used by PLMN2 to authenticate SIM2 to the UE and may include: SUPI (e.g., IMSI), GUTI, 5G-S-TMSI or SUCI. The partial registration request may be a newly defined procedure, or it may be combined as part of a general registration procedure. The multi-SIM indicator may be encoded as an option in the preferred network behavior parameter, or it may be a separate indicator. The multi-SIM indicator may be used by a network entity to check and select an appropriate network entity that supports multi-SIM operation during the registration process.

[0416] Step S1106: RAN1 forwards the partial registration request to AMF1 via the N2 interface previously established for SIM1. In the case of MUSIM registration, RAN1 selects AMF1 to process the request.

[0417] Step S1108: AMF1 determines which UDM to connect to by checking the SIM2 identifier. The SIM2 identifier may include the MCC and MNC used to determine the UDM that should be contacted.

[0418] Step S1110: AMF1 forwards the partial registration request to UDM2 and may include: a registration type set to partial registration or a partial registration indicator, a multi-SIM indication which may be encoded as an option in the preferred network behavior, (one or more) SIM2 identifiers, AMF1 ID and UE ID to indicate that the UE with SIM1 has authenticated with PLMN1, context information of the AMF in PLMN1 to which PLMN2 may forward future paging requests for SIM2, etc. Note that in step S1102, the registration type was set to initial registration for SIM1; however, this registration request is for SIM2, so the registration type is changed from initial registration to partial registration. Alternatively, the registration type may be set to initial registration and a partial registration indicator may be added to the request. The registration type from step S1102 may also be encoded as initial registration with partial registration.

[0419] Step S1112: UDM2 responds to AMF1 and AMF1 responds to the UE. The response indicates to the UE whether the UE is allowed to be partially registered and indicates to the UE that authentication is pending. The message also includes a timer that indicates to the UE how long it should wait before it receives a request to start authentication from the network. If the timer expires before the UE receives a request to start authentication from the network, the UE will ignore any request to perform authentication unless it sends another partial registration request. UDM2 may provide the UE with a temporary identifier for SIM2, which will be used to indicate when paging requests are targeted at SIM2. In addition, contact information for the default AMF may be included in the accept message to inform AMF1 that future paging requests may originate from the default AMF instead of the UDM. The RM state for SIM2 will not be updated, or may be updated to a state indicating authentication is pending.

[0420] Step S1114: The AMF initiates a slice-specific secondary authentication to the UE and the AUSF of PLMN2. This process is described in the section titled Slice-specific Authentication and Authorization above. UDM2 may provide the functionality of AAA-S 802 in this process. UDM2 may provide a temporary identifier to the UE by providing the temporary identifier to the AMF. The AMF may provide the temporary identifier to the UE in an EAP Success message. In addition, a registration timer for SIM2 may be provided. Figure 8 also shows AAA-P 804.

[0421] For partial registration, there is no AMF assigned to serve the UE, therefore, the UDM assigns a temporary UE ID to the UE. This temporary UE ID will be used to page the UE when there is activity for the UE, and the UE is in RM-INACTIVE state under the corresponding inactive PLMN. Note that the RM state in this case may be an indication in the subscription data stored in the UDM to indicate that paging request forwarding is enabled. For this case, the UDM of the inactive PLMN may send a paging message to the AMF in the active PLMN using the temporary UE ID assigned to the UE during the partial registration. In addition, the UDM may return an identifier and / or contact information of the default AMF in the response to the partial registration request. This default AMF may be used to send paging requests for the SIM whose UE is in RM-INACTIVE state under the PLMN to the AMF of the active PLMN to which the UE is currently registered.

[0422] Partial Attachment

[0423] A UE using multiple SIMs may use the partial attach enhancement to register not only the primary SIM to the current PLMN, but also the other secondary SIMs to their corresponding PLMNs. Fig.24 A process for a partial attach enhancement is shown. The figure shows that the partial attach is performed separately from the initial attach for SIM1, but it can also be combined together as one attach process, for example, in a MUSIM attach request as described below. In addition, the partial attach enhancement can support partial attach of multiple secondary SIMs by performing steps S2406 to S2414 for each SIM. Note that the partial attach enhancement enables the paging request forwarding functionality to originate from the HSS, which is a new functionality added to the HSS.

[0424] Step S2402: The UE initially attaches to PLMN1 using SIM1. PLMN1 is considered the active PLMN and SIM1 is considered the primary SIM. This step may initially be performed when only SIM1 is installed in the UE. In the case where two or more SIMs are installed in the UE at the same time, a combined attach procedure may be performed to register multiple SIMs together in one attach request. Such a combined attach request is called a MUSIM attach and may include a multi-SIM indicator, a partial attach indicator and an appropriate SIM identifier (e.g., IMSI, GUTI, etc.) for each SIM in addition to the information in a regular attach request. In this case, the partial attach is integrated as part of the attach procedure from TS 23.401 [9]. The multi-SIM indicator may be encoded as an option in the preferred network behavior parameter, or it may be a separate indicator and the partial attach indicator may be carried in the attach type parameter. The message may also indicate which SIM is the primary SIM and which SIMs are secondary SIMs and should be used to register to the inactive PLMN. For a combined attach request, the process jumps to step S2406.

[0425] Step S2404: At some later time, the partial attach procedure will begin. For example, this may occur when SIM2 is added to the UE by inserting a physical SIM, by configuration of an eSIM, based on a request from an application on the UE through a GUI or API, or immediately after completing the attach procedure with PLMN1. SIM2 is considered a secondary SIM and it is associated with PLMN2. PLMN2 is considered an inactive PLMN. The UE then performs a partial attach request to PLMN2 through PLMN1. This request may contain a multi-SIM indicator and an appropriate SIM identifier (e.g., IMSI, GUTI, etc.) for each SIM. The multi-SIM indicator may be encoded as an option in the preferred network behavior parameter, or it may be a separate indicator. The multi-SIM indicator may be used by a network entity to check and select an appropriate network entity that supports multi-SIM operation during the attach procedure and to enable paging request forwarding.

[0426] Step S2406: In response to the partial attach request or partial attach indication, the MME in PLMN1 selects an appropriate HSS to process the partial attach request for the corresponding SIM. The identifier provided for SIM2 may include an MCC and an MNC, or may be resolved to an MCC and an MNC for determining the HSS that should be contacted. Due to core network configuration, roaming agreements, or other mechanisms to support multi-SIM operation, the MME in PLMN1 may be provided with contact information for other HSSs of different PLMNs so that the MME can forward any partial attach messages for those secondary SIMs to the default HSS in the other PLMNs.

[0427] Step S2408: MME1 2402 sends a partial attach request to the selected HSS. The request may include a partial connection indicator, a multi-SIM indicator that may be encoded as an option in the preferred network behavior, (one or more) SIM2 identifiers, an MME1 ID and a UE ID indicating that the UE with SIM1 has authenticated to PLMN1, etc. MME1 may also provide context information of an MME in PLMN1 to which PLMN2 may forward paging requests for SIM2. This MME in PLMN1 may be configured to support paging request forwarding and may be able to forward the paging request from PLMN2 to the appropriate network entity (e.g., the MME to which the UE is attached in the case of UE mobility), so that the UE receives the paging.

[0428] Step S2410: The HSS in PLMN2 performs authentication of the UE for SIM2 and may store context information about the UE, such as information generated by the authentication process, and information provided by MME1. HSS2 2404 may also assign a temporary identifier to the UE for SIM2; this identifier may be used by HSS2 to identify paging requests for SIM2, which will be forwarded to the UE via PLMN1 in the future. Finally, the EMM state for SIM2 is set to EMM-INACTIVE in HSS2 to indicate that the UE with SIM2 is registered to PLMN2 but is not actively communicating with PLMN2. The EMM state in this case may be an indication stored in the subscription data in the HSS to indicate that paging request forwarding is enabled.

[0429] Step S2412: The HSS in PLMN2 returns a partial attach accept response to the MME in PLMN1 to indicate the result of the partial attach procedure. The response may include an indication that SIM2 authentication was successful, a temporary identifier assigned to SIM2 by HSS2, an indication that the UE's EMM state for SIM2 has changed from EMM-DEREGISTERED to EMM-INACTIVE, confirmation that reception of paging requests forwarded by PLMN1 for SIM1 is supported, contact information of the MME that received the paging request from PLMN1, and a registration timer for SIM2. If the partial attach is not accepted, the response may include further information detailing the reason why the attach was not accepted. In addition, contact information for the default MME may be included in the accept message to inform MME1 that future paging requests may originate from the default MME instead of from the HSS.

[0430] Step S2414: The MME in PLMN1 returns a partial attach accept message to the UE, which may be a modified attach accept message that provides additional information about the status of the partial attach process. If the attach process is performed for multiple SIMs, each SIM may have a separate registration status. The response message may include information returned from the HSS in PLMN2, such as an indication that SIM2 authentication was successful, a temporary identifier assigned to SIM2, an indication that the UE's EMM state for SIM2 has changed from EMM-DEREGISTERED to EMM-INACTIVE, and a registration timer for SIM2. The temporary identifier will be used to identify future paging requests for SIM2, which are forwarded to PLMN1. In addition, the MME in PLMN1 may assign a separate temporary identifier to SIM2 that can be used to page the UE, rather than using the temporary identifier assigned by PLMN2. The assignment of this temporary identifier may cause the associated paging occasion to overlap with the paging occasion associated with SIM1. Therefore, the UE will only need to monitor one paging occasion in order to receive paging for both SIM1 and SIM2. The MME may alternatively assign the same temporary identifier to all SIMs associated with the UE while maintaining the fact that the UE only needs to monitor one paging occasion and can receive paging for all SIMs. The EMM status for each SIM of the UE is updated. In this scenario, the EMM status for SIM1 is EMM-REGISTERED, while the EMM status for SIM2 is EMM-INACTIVE. Similarly, the EMM status in the MME of PLMN1 is EMM-REGISTERED for SIM1 and EMM-INACTIVE for SIM2. The MME in PLMN1 may maintain separate EMM status for SIM1 and SIM2, respectively.

[0431] Indirect registration

[0432] The indirect registration procedure is a functional combination of the partial registration procedure and the general registration procedure. Both the partial and indirect registration procedures include a multi-SIM indication and (one or more) SIM2 identifiers to configure PLMN2 to forward paging requests to the UE through PLMN1. However, the indicators used for each procedure are different (i.e., indirect vs. partial), and the indirect registration procedure provides additional functionality for the PLMN to allocate network slices and provide UE policy information to the UE. Indirect registration also assigns the AMF to serve the UE.

[0433] Fig.12 It is shown that the UE initiates an indirect registration procedure for SIM2 through PLMN1. Note that, similar to the partial registration procedure, the indirect registration procedure can be integrated with the universal registration procedure so that both SIM1 (direct registration) and SIM2 (indirect registration) are registered together in one request. This process may be referred to as MUSIM registration as described below. Similarly, the indirect registration procedure may also be performed separately from the universal registration procedure.

[0434] Step S1202: The UE registers SIM1 with PLMN1, where the registration type is initial registration. At this point, only SIM1 is installed in the UE. However, if SIM1 and SIM2 are installed at the same time, then when the UE registers SIM1 with PLMN1, the UE may also include a multi-SIM indication, an indirect registration indication, (one or more) appropriate SIM2 identifiers (e.g., SUPI (e.g., IMSI), GUTI, 5G-S-TMSI or SUCI), and the identity of PLMN2. In this case, the indirect registration request for SIM2 is part of the general registration process for SIM1, for example as a MUSIM registration. The addition to the initial registration request will include the multi-SIM indication, the indirect registration indicator, (one or more) SIM2 identifiers and the identity of PLMN2. The multi-SIM indicator may be encoded as an option in the preferred network behavior parameter, or it may be a separate indicator and the indirect registration indicator may be combined in the registration type parameter. The message may also indicate which SIM is the primary SIM and which SIMs are secondary SIMs and should be used to register to an inactive PLMN. In this case, the process jumps to step S1206, and the universal registration for SIM1 and the indirect registration for SIM2 can be performed concurrently or serially, for example, registering SIM1 first and then registering SIM2.

[0435] Step S1204: At some time after the UE successfully registers SIM1 with PLMN1 and SIM2 is installed in the UE, the UE may initiate an indirect registration request to inform PLMN1 that the UE is a multi-SIM device and include a multi-SIM indication, (one or more) SIM2 identifiers and the identity of PLMN2. The registration type for this request may be an indirect registration or an indirect registration indicator may be provided. At this time, the RM state for SIM1 is RM-REGISTERED, and the RM state for SIM2 (under PLMN2) is RM-DEREGISTERED. (One or more) SIM2 identifiers will be used by PLMN2 to authenticate SIM2 to the UE and may include: SUPI (e.g., IMSI), GUTI, 5G-S-TMSI or SUCI. The indirect registration request may be a newly defined procedure, or it may be combined as part of a general registration procedure, with the registration type set to indirect registration or including an indirect registration indicator. The multi-SIM indicator may be encoded as an option in the preferred network behavior parameter, or it may be a separate indicator. The multi-SIM indicator may be used by a network entity to check and select an appropriate network entity that supports multi-SIM operation during the registration process.

[0436] Step S1206: RAN1 902 forwards the general or indirect registration request to AMF1 904 via the N2 interface previously established for SIM1. In the case of MUSIM registration, RAN1 902 selects AMF1 904 to handle the request.

[0437] Step S1208: AMF1 904 executes Fig.10 11 to authenticate the UE for SIM2. This step completes the partial registration process of the UE for SIM2 and enables PLMN2 to forward paging requests originating from UDM2 to the UE. In addition, the contact information of the default AMF may be included in the accept message to inform AMF1 that future paging requests may originate from the default AMF instead of from UDM.

[0438] Steps S1210a and b: AMF1 requests the slice selection subscription data of the UE from UDM2, and UDM2 responds to AMF1 with the slice selection data.

[0439] Steps S1212a and b: AMF1 uses the slice selection data retrieved from steps S1210a and b and performs a Nnssf_NSSelection_Get request to NSSF2 1204 via NSSF1 1202. AMF1 provides the requested NSSAI and other slice related parameters to NSSF2. NSSF2 returns a response including the allowed NSSAI and other NSSAI related parameters and (one or more) NRFs 302 so that AMF1 selects NF / service for the network slice instance.

[0440] Steps S1214a and b: AMF1 queries NRF2 1208 through NRF1 1206 to find a suitable AMF to serve the UE's indirect registration request. NRF2 returns a list of potential AMFs within PLMN2 to handle the indirect registration request.

[0441] Step S1216: AMF1 forwards the indirect registration request to AMF2 and AMF2 performs a universal registration procedure for the UE using SIM2. This universal registration procedure may also include a multi-SIM indication, an indirect registration indicator, and (one or more) appropriate SIM2 identifiers or temporary identifiers received in step S1208. AMF1 may obtain the contact information of AMF2 from step S1214 via NRF2, or from step S1208 via UDM2 through a network configuration that supports multi-SIM operation (e.g., through a roaming agreement). After completing the universal registration procedure, the registration accept message returned to AMF1 may include an indication of successful SIM2 authentication, a temporary identifier assigned to the UE by AMF2 for SIM2, an indication that the RM state of the UE's SIM2 has changed from RM-DEREGISTERED to RM-INACTIVE, a confirmation of supporting the reception of a paging request forwarded by PLMN1 for SIM1, the contact information of the MME that receives the paging request from PLMN1, and the registration timer of SIM2. When the UE is actively registered to PLMN1, whenever there is a paging for SIM2, the UE will be paged from PLMN2 using the UE's temporary identifier. Alternatively, AMF1 may assign a separate temporary identifier to SIM2, which may be used instead to page the UE in PLMN1. The assignment of this temporary identifier may cause the associated paging occasion to overlap with the paging occasion associated with SIM1. Therefore, the UE will only need to monitor one paging occasion in order to receive paging for SIM1 and SIM2. AMF1 may alternatively assign the same temporary identifier to all SIMs associated with the UE, while maintaining the fact that the UE only needs to monitor one paging occasion and can receive paging for all SIMs. The UE's RM state for each SIM is updated in the UE and should match the state in AMF1: RM-REGISTERED for SIM1 and RM-INACTIVE for SIM2.

[0442] Step S1218: AMF1 returns the registration accept message received from AMF2 to RAN1 and RAN1 forwards the registration accept message to the UE. The accept message may include an indication that SIM2 authentication is successful, a temporary identifier assigned to the UE for SIM2 by the general registration procedure or AMF1, an indication that the RM state of SIM2 of the UE has changed from RM-DEREGISTERED to RM-INACTIVE, and a registration timer for SIM2. When the UE actively registers to PLMN1, the UE's temporary identifier will be used to page the UE whenever there is a paging for SIM2.

[0443] Fig.13 An alternative procedure for indirect registration is shown in TS 23.502 [2], where AMF1 is provided with contact information for AMF2 as part of support for multi-SIM operation. AMF2 is configured as the default AMF in PLMN2 for AMF1 to contact in the case of multi-SIM support. Upon receiving the indirect registration request, AMF1 may look up its contact list for PLMN2 and forward the indirect registration request directly to AMF2. It is possible for AMF2 to select another AMF within PLMN2 to serve the UE based on the request forwarded from AMF1. From that point on, the generic registration procedure from TS 23.502 [2] is performed, but is updated to take into account the changes to support indirect registration.

[0444] Steps S1302-S1306: These steps are similar to Fig.12 The steps performed in the process shown in are the same.

[0445] Step S1308: AMF1 has been provided with contact information for AMF2 and sends an indirect registration for the UE of SIM2 to PLMN2. AMF1 makes this determination based on the presence of a multi-SIM indication or if the registration type or indicator is set to indirect registration. The indirect registration request may include: a registration type or indirect registration indicator set to indirect registration, a multi-SIM indication that may be encoded as an option in a preferred network behavior, (one or more) SIM2 identifiers, an AMF1 ID and UE ID indicating that the UE with SIM1 has authenticated to PLMN1, context information of the AMF in PLMN1 to which PLMN2 may forward future paging requests for SIM2, and the like. If the request in step S1302 is a general registration request, then AMF1 generates a new indirect registration request, where the registration type may be set to indirect registration and both the multi-SIM indication and (one or more) SIM2 identifiers are provided. Alternatively, the registration type may be set to initial registration and the indirect registration indicator may be added to the request. The registration type may also be encoded as initial registration with partial registration.

[0446] Step S1310: The generic registration procedure from TS 23.502 [2] is performed for SIM2 on PLMN2, but is modified to include functionality to support indirect registration, such as Fig.12 as shown in .

[0447] Step S1312: AMF1 returns the registration accept message received from AMF2 to RAN1 and RAN1 forwards the registration accept message to the UE. The accept message may contain an indication that SIM2 has been successfully authenticated, a temporary identifier assigned to the UE for SIM2 by the general registration procedure, an indication that the RM state of the UE for SIM2 has changed from RM-DEREGISTERED to RM-INACTIVE, a confirmation that it supports receiving paging requests forwarded by PLMN1 for SIM1, contact information of the MME that received the paging request from PLMN1, and a registration timer for SIM2. When the UE is actively registered to PLMN1, the UE will be paged from PLMN2 using the UE's temporary identifier whenever there is paging for SIM2. Alternatively, AMF1 may assign a separate temporary identifier to SIM2, which may be used to page the UE in PLMN1 instead. The assignment of this temporary identifier may cause the associated paging occasion to overlap with the paging occasion associated with SIM1. Therefore, the UE will only need to monitor one paging occasion in order to receive paging for SIM1 and SIM2. AMF1 may alternatively assign the same temporary identifier to all SIMs associated with the UE, while maintaining the fact that the UE only needs to monitor one paging occasion and can receive paging for all SIMs. The UE's RM state for each SIM is updated in the UE and should match the state in AMF1: RM-REGISTERED for SIM1 and RM-INACTIVE for SIM2.

[0448] The indirect registration may also be performed after the UE has registered each of the SIMs with the respective PLMNs (regardless of whether the PLMNs are the same or different). In other words, a multi-SIM UE first registers SIM1 with PLMN1, then registers SIM2 with PLMN2, and finally performs the indirect registration. Note that the order of registration with PLMN1 and PLMN2 is irrelevant. After the SIMs are registered with the respective PLMNs, the UE may then decide to operate primarily on one of the SIMs, such as the user-configured primary SIM (e.g., SIM1). In this case, the UE may perform an indirect registration for SIM2 from PLMN1 to PLMN2 via the user plane of PLMN1.

[0449] Fig.39 The process of performing indirect registration for an inactive SIM by a multi-SIM UE through the user plane of the active SIM is shown. Before performing the indirect registration process, the UE has been registered with the corresponding PLMNs respectively, for example, SIM1 is registered with PLMN1 and SIM2 is registered with PLMN2. Then, the UE performs the indirect registration process for SIM2 using the PDU session created for SIM1 on PLMN1. The user of the UE can trigger this process by configuring the UE so that SIM1 is the preferred SIM, or the user wants to maintain connection to PLMN1 for a specific duration to complete important activities, while also being able to receive mobile terminated services for SIM2, such as paging requests.

[0450] Step S3902: The UE registers the corresponding SIMs with PLMN1 and PLMN2 separately. As part of multi-SIM operation, the UE will periodically switch communications between the two PLMNs to monitor paging messages and ensure that the registration status for each SIM remains RM-REGISTERED.

[0451] Step S3904: The UE establishes (one or more) PDU sessions for SIM1 on PLMN1 to establish a data connection. One or more PDU sessions may be created. One of the PDU sessions may be established for an important activity, such as a voice call made by the user of the UE or an important download that the user does not want to be interrupted. Another PDU session may be associated with a general connection to the Internet established after the UE registers with the PLMN. In addition, the UE also establishes (one or more) PDU sessions for SIM2 on PLMN2.

[0452] Step S3906: If the SIM1 activity from step S3904 is important to the user of the UE, then the user may configure via the GUI that the service for SIM1 will not be interrupted. This configuration causes the UE to disable switching communications between the two PLMNs and maintain the connection with PLMN1, possibly for a configured duration, a configured location, etc. Alternatively, the user of the UE may have configured SIM1 to be the primary SIM and SIM2 to be the secondary SIM. Therefore, the UE determines that the user prefers to maintain the connection with PLMN1.

[0453] Step S3908: As a result of the decision made in step S3906, the UE sends an indirect registration request to the N3IWF of PLMN2 through the user plane of PLMN1. The UE sends the indirect registration using the PDU session created in step S3904 and the address of the N3IWF2 provided to the UE in the access and mobility policy delivered to the UE by the PCF from PLMN2. The registration message may include the following information in the request: multi-SIM indicator, indirect registration indicator, SIM2 identifier, optional duration, location information, whether PLMN2 should buffer downlink data for the UE, whether the UE is reachable on the user plane of PLMN1, etc. The UE may obtain its own public IP address through an external mechanism (e.g., STUN protocol) and provide the address to N3IWF2 in the indirect registration message. If a unique IPv6 address or prefix is ​​assigned to the UE, the UE may provide the address or prefix to N3IWF2 in the indirect registration message. Alternatively, the UE may establish a secure tunnel to N3IWF2 to enable the proposed functionality. The UE may also indicate the PDU Session ID in a NAS notification sent to the UE over the user plane of PLMN1 to associate with future paging requests provided by PLMN2. The PDU Session ID may be a PDU session previously established by the UE on PLMN2.

[0454] Step S3910: AMF2 processes the registration request received from the UE via the N3IWF of PLMN2. The presence of the multi-SIM indicator informs the AMF that the UE is a multi-SIM device and the indirect registration request indication can reach the UE via the user plane of the PLMN from which this request originates. If a duration is provided to indicate how long the UE will remain connected to PLMN1, the AMF can reset or suspend the registration timer associated with SIM2 and enable a new suspension timer based on the value provided by the UE. AMF2 returns an acceptance response for the indirect registration, which may include: the status of the request, the time value that the AMF will suspend the UE's registration, the PDU session ID that PLMN2 will associate with future paging requests forwarded to the UE (if it was not provided by the UE), etc.

[0455] Fig.39 The procedure shown in enables PLMN2 to forward paging requests to the UE via the user plane of PLMN1. It is assumed that the UE will maintain the PDU Session established on PLMN1 in order to be able to receive NAS notifications that may be received from PLMN2. Before releasing the PDU Session on PLMN1, the UE may need to inform PLMN2 that it will no longer be reachable via the user plane of PLMN1. If a secure tunnel is created, then the UE will be able to receive paging requests as long as the secure tunnel is valid.

[0456] Indirect attachment

[0457] An alternative to partial attach in LTE is indirect attach enhancements, such as Fig.25 . An indirect attach can be considered as an initial attach procedure, but it is performed indirectly from another PLMN instead of directly at the home PLMN, with the added functionality of supporting multi-SIM operation. In this case, the indirect attach procedure is performed for SIM2 via PLMN1. As a result, context information about the registration of SIM2 is established in the MME of PLMN2, and a default bearer may also be created in the SGW and PGW of PLMN2. Similar to the partial attach case, the indirect attach may be combined with Fig.25 The indirect attach also assigns the MME to serve the UE.

[0458] Step S2502: The UE performs an attach procedure for SIM1 to PLMN1 (i.e., the active PLMN). This step may initially be performed when only SIM1 is installed in the UE. In the case where two or more SIMs are installed in the UE at the same time, a combined attach procedure may be performed to register multiple SIMs together in one attach request. This combined attach request may include a multi-SIM indicator, an indirect attach indicator, an appropriate SIM identifier (e.g., IMSI, GUTI, etc.) for each SIM, and the identity of PLMN2 when the UE registers with PLMN1 for SIM1. In this case, the indirect attach is integrated as part of the attach procedure from TS23.401 and may be referred to as MUSIM attach described below. The multi-SIM indicator may be encoded as an option in the preferred network behavior parameter, or it may be a separate indicator, and the indirect attach indicator may be carried in the attach type parameter. The message may also indicate which SIM is the primary SIM and which SIMs are secondary SIMs and should be used to register to the inactive PLMN. For a MUSIM attach request, the process jumps to step S2506, and the requests may be executed concurrently or sequentially, for example, registering SIM1 first and then registering SIM2.

[0459] Step S2504: At some later time, the indirect attach procedure will begin. For example, this may occur by inserting a physical SIM, by configuration of an eSIM, based on a request from an application on the UE through a GUI, or immediately upon completion of the attach procedure with PLMN1 when SIM2 is added to the UE. SIM2 is considered a secondary SIM and it is associated with PLMN2, which is considered an inactive PLMN. The UE then performs an indirect attach request to PLMN2 through PLMN1. This request may contain a multi-SIM indicator, the appropriate SIM identifiers (e.g., IMSI, GUTI, etc.) for each SIM card, and the identities of the other PLMNs. The multi-SIM indicator may be encoded as an option in the preferred network behavior parameter or it may be a separate indicator. The multi-SIM indicator may be used by a network entity to check and select an appropriate network entity that supports multi-SIM operation and is used to enable paging request forwarding during the attach procedure.

[0460] Step S2506: In response to the indirect attach request or the indirect attach indication, the MME in PLMN1 selects an appropriate MME to process the indirect attach request of the corresponding SIM. The identifier provided for SIM2 may include an MCC and an MNC, or may be resolved to an MCC and an MNC for determining the MME that should be contacted. Due to core network configuration, roaming agreement, or other mechanisms to support multi-SIM operation, the MME in PLMN1 may be provided with contact information of other MMEs in different PLMNs so that the MME in PLMN1 can forward the indirect attach request to the corresponding MME.

[0461] Step S2508: MME1 sends an indirect attach request to the selected MME. The request may include an indirect attach indicator, a multi-SIM indicator, (one or more) SIM2 identifiers, and other information required for the attach request. In addition, the MME1 ID and UE ID associated with SIM1 may be provided to inform the MME in PLMN2 that SIM1 has been authenticated to PLMN1. MME1 may also provide context information of the MME in PLMN1, and PLMN2 may forward paging requests for SIM2 to PLMN1 or receive paging requests for SIM1 from PLMN1. This MME in PLMN1 may be configured to support paging request forwarding and may be able to forward paging requests from PLMN2 to the appropriate network entity (e.g., the MME to which the UE is attached in the case of UE mobility), so that the UE receives the paging. The MME may also forward paging requests for SIM1 from PLMN1 to PLMN2 during the time that the UE is connected to PLMN2.

[0462] Step S2510: The indirect attach request is processed as outlined in steps 3 to 17 of the E-UTRAN 3202 attach procedure in TS 23.401. Note that the NAS message response sent in step S2006 is rerouted to the MME in PLMN1, rather than to the RAN node in PLMN2. The indirect attach accept response received from this procedure includes the status of the outcome of the procedure. The response may include an indication that SIM2 authentication was successful, a temporary identifier assigned to SIM2 by MME2 2502, an indication that the UE's EMM state for SIM2 has changed from EMM-DEREGISTERED to EMM-INACTIVE, confirmation that reception of paging requests forwarded by PLMN1 for SIM1 is supported, contact information of the MME that received the paging request from PLMN1, and a registration timer for SIM2. If the indirect attach is not accepted, the response may include further information detailing the reason why the attach was not accepted.

[0463] Step S2512: The MME in PLMN1 returns an indirect attach accept message to the UE, which may be a modified attach accept message that provides additional information about the status of the indirect attach process. If the attach process is performed for multiple SIMs, each SIM may have a separate registration status. The response message may include information returned from the MME in PLMN2, such as a temporary identifier, an indication that SIM2 authentication was successful. The temporary identifier assigned to SIM2 will be used to identify future paging requests for SIM2 forwarded to PLMN1. In addition, the MME in PLMN1 may assign a separate temporary identifier to SIM2, which may be used to page the UE instead of using the temporary identifier assigned by PLMN2. The assignment of this temporary identifier may cause the associated paging occasion to overlap with the paging occasion associated with SIM1. Therefore, the UE will only need to monitor one paging occasion in order to receive paging for SIM1 and SIM2. The MME may alternatively assign the same temporary identifier to all SIMs associated with the UE, while maintaining the fact that the UE only needs to monitor one paging occasion and can receive paging for all SIMs. The EMM status of the UE for each SIM is updated. In this case, the EMM status for SIM1 is EMM-REGISTERED, while the EMM status for SIM2 is EMM-INACTIVE. Similarly, the EMM status in the MME of PLMN1 is EMM-REGISTERED for SIM1 and EMM-INACTIVE for SIM2. Finally, the EMM status in the MME of PLMN2 is EMM-INACTIVE for SIM2. Fig.25 Also included is SGW2 2504 and PGW2 2506.

[0464] Similar to Fig.39 The indirect registration performed on the user plane in 5G shown in , an indirect attach request can also be sent on the user plane in LTE. The process will be performed in a similar manner, but the messages and entities involved are LTE messages and entities. For example, the indirect registration message is replaced with an indirect attach message, which will be passed through the LTE RAN, SGW / PGW, ePDG and MME. The LTE RAN and SGW / PGW are associated with PLMN1, while the ePDG and MME are associated with PLMN2. These policies can come from the Access Network Discovery Selection Function (ANDSF) policy for PLMN2.

[0465] MUSIM Registration / Attachment

[0466] Another enhancement to 5G and LTE systems for supporting multiple SIMs is through the introduction of a MUSIM registration or attach procedure, where the UE can register multiple SIMs in the same registration or attach request. This MUSIM registration or attach procedure can support registering SIMs to the same or different PLMNs, depending on which operators have issued those SIMs. For SIMs obtained from the same operator, the SIMs can be registered to the same PLMN and separate UE contexts can be created within the PLMN, one for each SIM. In addition, the UE contexts can be linked together to provide optimization when forwarding paging requests. For SIMs obtained from different operators, the UE can request the network to register the SIM associated with the active PLMN and then register SIMs from other operators to their associated PLMNs. When registering SIMs to different PLMNs, the core network can use the partial or indirect registration / attachment procedures described above. Fig.26 An example MUSIM attach process is shown in more detail. Note that this figure uses terminology related to LTE, but the process can also be applicable to 5G systems.

[0467] Step S2602: Two SIMs are installed in a UE with MUSIM capability. SIM1 is the primary SIM and is associated with PLMN1, while SIM2 is the secondary SIM and is associated with PLMN2. Note that the figure shows only two SIMs, but it is understood that more than two SIMs may be installed in the UE and the process will remain the same, except that the attach process will be extended to each installed SIM.

[0468] Step S2604: The UE performs a MUSIM attach request, where each installed SIM will be registered to the associated PLMN. In addition to other data required for the attach procedure, the request may also include the following: a multi-SIM indicator and an identifier for each SIM. In addition, a partial attach or indirect attach indication may be provided to inform the MME in PLMN1 how to register SIMs associated with different PLMNs. This indication may be provided on a per-SIM basis or for all SIMs in common. If the attach procedure from TS23.401 is enhanced to integrate the MUSIM functionality proposed herein, the multi-SIM indicator may be encoded as an option in the preferred network behavior parameter, or it may be a separate indicator and the partial / indirect attach indicator may be carried in the attach type parameter. The message may also indicate which SIM is the primary SIM and which SIMs are secondary SIMs and should be used to register to an inactive PLMN.

[0469] Step S2606: The MME in PLMN1 performs an attach procedure for the primary SIM. The UE is authenticated and authorized, and a registration context is created for SIM1 on MME1. This process may also create a default bearer for the UE in the SGW and PGW of PLMN1. Since SIM1 is the primary SIM, if the attach is successful, the EMM status for SIM1 in the MME will be set to EMM-REGISTERED.

[0470] Step S2608: The MME in PLMN1 may also register other SIMs that belong to the same operator as SIM1. If SIM2 belongs to the same operator as SIM1, then an attach procedure is performed for SIM2 and a registration context is created in the MME for SIM2, separate from the registration context of SIM1. However, the UE contexts may be linked together to provide optimization when forwarding paging requests. If the attach is successful, then the EMM state for SIM2 will be EMM-INACTIVE since it is not the primary SIM in the UE. This step may be repeated for multiple SIMs that belong to the same PLMN as SIM1. In this specific case, since SIM2 belongs to another PLMN, step S2608 is skipped.

[0471] Step S2610: The MME in PLMN1 performs a partial or indirect attach of SIM2 to PLMN2. The UE may have provided an indication in step S2604 of which attach request to perform or the MME may be configured to perform which attach procedure, or the core network may have a system policy indicating which attach procedure to perform. The MME in PLMN1 sets the EMM status for each SIM here to EMM-INACTIVE. The EMM status of each SIM in its corresponding PLMN is also set to EMM-INACTIVE. The information exchanged between PLMN1 and PLMN2 is the same as previously specified and may be within an encrypted NAS container for certain information to protect the privacy of the UE.

[0472] Step S2612: The MME in PLMN1 aggregates all the attach accept results for each SIM and returns them to the UE. Instead of paging the UE using temporary identifiers assigned by other PLMNs, the MME in PLMN1 may assign a separate temporary identifier to each SIM that can be used to page the UE. The assignment of these temporary identifiers may make the associated paging occasions overlap or be very close to the paging occasions associated with the primary SIM. Therefore, the UE will only need to monitor paging occasions that are close to each other in order to be able to receive paging for all SIMs. The MME may alternatively assign the same temporary identifier to all SIMs associated with the UE, so that the UE only needs to monitor one paging occasion but is able to receive paging for all SIMs. After receiving the attach accept, the UE sets the appropriate EMM state for each SIM. In this particular case, the EMM state for SIM1 in the UE is EMM-REGISTERED, while the EMM state for SIM2 is EMM-INACTIVE.

[0473] 5G registration status for multi-SIM operation

[0474] New Registration Management (RM) states are proposed to support multi-SIM operation in 5GS. The new state called RM-INACTIVE refers to the RM state of the UE with an inactive PLMN. Furthermore, this state indicates the fact that the PLMN has authenticated the SIM for use in the core network. Any existing UE contexts and PDU sessions within the core network associated with the SIM / UE will be maintained as if the UE was in RM-REGISTERED, CM-IDLE and RRC_IDLE or RRC_INACTIVE states. Therefore, when the UE is in RM-INACTIVE state, it must also be in CM-IDLE and RRC_IDLE or RRC_INACTIVE states.

[0475] The RM-INACTIVE status indicates the following (refer to Fig. 9 SIM and PLMN in the SIM card):

[0476] • The UE is registered to PLMN2 for SIM2 and can receive services (e.g., voice or IMS calls, SMS messages, etc.) from PLMN2.

[0477] · The UE is in CM-IDLE state and there is no NAS signalling with the PLMN2 core network.

[0478] • The UE is not connected to any RAN node of PLMN2, and therefore does not monitor paging occasions from PLMN2 for SIM2.

[0479] • The UE may receive paging requests for SIM2 if they are forwarded by PLMN2 to PLMN1.

[0480] PLMN2’s AMF (or UDM) can page the UE by forwarding the paging request for SIM2 to PLMN1’s AMF

[0481] The AMF of PLMN2 is not aware of the location of the UE.

[0482] The security context may be stored in the AMF within PLMN2 to protect NAS messages between the UE and PLMN2.

[0483] Fig.14 The updated RM management states are shown to include the RM-INACTIVE state. The UE may transition from the indicated RM state to the RM-INACTIVE state by performing the listed procedures.

[0484] From RM-DEREGISTERED state to RM-INACTIVE state:

[0485] οPerform part of the registration process

[0486] οPerform indirect registration process

[0487] From RM-REGISTERED state to RM-INACTIVE state:

[0488] o Perform SIM switch (e.g., periodic registration update) procedures

[0489] The UE may transition out of the RM-INACTIVE state as follows.

[0490] From RM-INACTIVE to RM-REGISTERED

[0491] οPerform the registration process

[0492] o Perform SIM switch (e.g., periodic registration update) procedures

[0493] From RM-INACTIVE to RM-DEREGISTERED

[0494] οExecute the deregistration process (UE or network initiated)

[0495] If the UE does not perform a periodic registration update in time in RM-INACTIVE state (e.g. the registration timer (in a multi-SIM policy) expires before the UE performs a periodic registration update procedure), then the core network may initiate a deregistration procedure.

[0496] οRegistration update request unsuccessful

[0497] When the UE performs a SIM switching procedure and if the switching is accepted by the core network, the UE's RM state transitions from RM-REGISTERED to RM-INACTIVE. However, if the switching is rejected, the UE's RM state transitions to RM-DEREGISTERED.

[0498] In the above description, it is proposed to update the RM state model to include a new state RM-INACTIVE. However, there may be complications in the UE implementation when introducing a new state into the state model. Therefore, the new RM-INACTIVE state can be regarded as a sub-state of the RM-REGISTERED state or as an operating mode within the RM-REGISTERED state, because both the RM-INACTIVE and RM-REGISTERED states infer that the UE is registered to the core network and can receive services from the core network. In addition, many characteristics of RM-INACTIVE are similar to those of the RM-REGISTERED state. However, one major difference is that the UE does not actively monitor paging occasions from inactive PLMNs, therefore requiring paging request forwarding. RM-INACTIVE can be referred to as an "inactive registration" sub-state or an operating mode of the RM-REGISTERED state. Therefore, this "inactive registration" sub-state or mode can replace the "inactive registration" sub-state or mode of operation of the RM-REGISTERED state. Fig.14 Neutralizes the RM-INACTIVE state mentioned elsewhere in this disclosure.

[0499] LTE mobility management states for multi-SIM operation

[0500] Similarly, the Enhanced Mobility Management (EMM) state in LTE provides similar functionality to that of the 5GS Registration Management state. In order to support the UE to register secondary SIMs to their corresponding PLMNs, new EMM states are proposed to inform all entities of the registration status of these secondary SIMs. The new state EMM-INACTIVE captures the fact that the secondary SIM is registered to the PLMN, but the UE is not in active communication with that PLMN. Active communication refers to the fact that the UE is in the EMM-REGISTERED state and may be in either the ECM-IDLE or ECM-CONNECTED state. In other words, the UE can receive NAS notifications or can be paged from the core network. The UE context can be saved within the PLMN so that the UE receives, for example, phone calls or short messages, even if it is not in active communication with the PLMN.

[0501] The EMM-INACTIVE status indicates the following (refer to Fig.25 SIM and PLMN in the SIM card):

[0502] • The UE is registered to PLMN2 for SIM2 and can receive services (e.g., voice or IMS calls, SMS messages, etc.) from PLMN2.

[0503] The UE is in ECM-IDLE state and there is no NAS signalling with the core network of PLMN2.

[0504] • The UE is not connected to any RAN node of PLMN2 and therefore does not actively monitor paging requests for SIM2 from RAN nodes of PLMN2.

[0505] • The UE may receive paging requests for SIM2 if they are forwarded by PLMN2 to PLMN1.

[0506] • The MME (or HSS) of PLMN2 may page the UE by forwarding the paging request for SIM2 to the MME of PLMN1.

[0507] The MME of PLMN2 does not know the location of the UE.

[0508] • The security context is stored in the MME of PLMN2 and is used to protect messages from PLMN2 to the UE.

[0509] Fig. 27 The EMM state model in conjunction with the new state EMM-INACTIVE state is shown. This state transition model is implemented in both the UE and the MME. The UE can transition from the indicated EMM state to the EMM-INACTIVE state by executing the listed procedures.

[0510] From EMM-DEREGISTERED state to EMM-INACTIVE state:

[0511] oPerform a partial attachment process

[0512] o Perform an indirect attachment process

[0513] From EMM-REGISTERED state to EMM-INACTIVE state:

[0514] o Perform SIM switch (e.g., registration update request) process

[0515] The UE may transition out of the EMM-INACTIVE state as follows.

[0516] From EMM-INACTIVE state to EMM-REGISTERED state:

[0517] οExecute the attachment process

[0518] o Perform SIM switch (e.g., registration update request) process

[0519] From EMM-INACTIVE state to EMM-DEREGISTERED state:

[0520] o Execute the detach procedure (UE or network initiated)

[0521] If the UE does not periodically update the attach timer in the EMM-INACTIVE state, the core network may initiate a detach procedure.

[0522] οRegistration update request unsuccessful

[0523] When the UE performs a SIM switching procedure and if the switching is accepted by the core network, the UE's EMM state transitions from EMM-REGISTERED to EMM-INACTIVE. However, if the switching is rejected, the UE's EMM state transitions to EMM-DEREGISTERED.

[0524] In the above description, it is proposed to update the EMM state model to include a new state EMM-INACTIVE. In theory, the proposed new state provides a clear functional division from the existing states and provides new functionality introduced by supporting multiple SIM UEs. However, in practice, the new state may not be feasible considering existing deployments. To this end, the new EMM-INACTIVE state can be viewed as a sub-state of the EMM-REGISTERED state or as an operation mode within the EMM-REGISTERED state, as both states infer that the UE is registered to the core network and can receive services from the core network. Furthermore, many characteristics of EMM-INACTIVE are similar to those of the EMM-REGISTERED state. However, one major difference is that the UE is not actively monitoring paging requests on the inactive PLMN, thus requiring paging request forwarding. Return to reference Fig.25 In the example in Figure 1, the UE will be in the EMM-REGISTERED state under PLMN2 (for SIM2), but operating in the "Inactive Registration" sub-state or mode, which requires PLMN2 to forward any paging requests to the UE via PLMN1. Therefore, EMM-INACTIVE can be equivalent to the "Inactive Registration" sub-state or mode of the EMM-REGISTERED state. Therefore, this "Inactive Registration" sub-state or mode can replace Fig. 27 Neutralizes the EMM-INACTIVE state referred to elsewhere in this disclosure.

[0525] The EMM states of each SIM in the UE can be combined within the UE to provide optimized operation, which will reduce the power consumption of multi-SIM operation. For example, instead of performing PLMN and cell selection for each SIM, a multi-SIM UE can minimize power consumption by performing PLMN and cell selection only for the active SIM or target PLMN when attempting to connect to the target PLMN after the SIM switching process. Similarly, for an inactive SIM, certain timers, such as DRX timers and other NAS timers, may not need to be maintained. Table 1 shows an example of a dual SIM UE where optimization can be achieved based on the EMM state of each SIM. Note that the table shows the case of two SIMs, but it can be easily extended to support more than two SIMs. Some of these state combinations are temporary, such as the EMM-INACTIVE state for two SIMs, which may temporarily appear during the SIM switching process.

[0526] Table 1 – UE NAS operations for multi-SIM UE to reduce power consumption

[0527]

[0528]

[0529] Multi-SIM paging operation

[0530] After the UE registers and the registration status of SIM1 and SIM2 are linked to the corresponding PLMN, paging requests associated with either SIM will be sent to the UE on the active PLMN. Within each PLMN, the registration status for each SIM can be saved and linked together to inform the PLMN that these SIMs belong to the same UE. Fig.15 An example of paging originating in PLMN2 (inactive PLMN) and received by the UE through PLMN1 (active PLMN) is shown. Within PLMN1, the registration state for SIM1 is RM-REGISTERED and the registration state for SIM2 is RM-INACTIVE (or the "inactive registration" substate or mode of RM-REGISTERED). In addition, PLMN1 can maintain a temporary identifier mapping between SIMs so that paging requests can be forwarded from PLMN2 to the UE.

[0531] Step S1502: When the RM state of the UE under PLMN2 is RM-INACTIVE, the UE has performed a partial registration or an indirect registration with PLMN2 for SIM2 so as to forward paging for SIM2 to PLMN1. The UE is in RM-REGISTERED and CM-IDLE under PLMN1. The UE may provide multi-SIM assistance information to the PLMN of each SIM to configure the PLMN with respect to the user's preference for multi-SIM operation. The multi-SIM assistance information will be described in more detail below.

[0532] Step S1504: The UE monitors a paging occasion associated with either SIM1 or SIM2; for example, if the UE is provided with a temporary identifier for SIM1 and another temporary identifier for SIM2 from the AMF in PLMN1. Note that the AMF may have assigned temporary identifiers in such a way that the paging occasions calculated from each identifier overlap simultaneously, which minimizes the time the UE needs to monitor the paging occasions. Therefore, the UE only needs to monitor one paging occasion applicable to both SIMs. For the case where there are more than two SIMs, the AMF may have assigned temporary identifiers so that the paging occasions do not conflict with each other and can be very close to each other. In these cases, the UE may have to monitor multiple paging occasions but still be able to receive paging for all SIMs without paging conflicts. Alternatively, the AMF may assign the same temporary identifier to all SIMs associated with the UE, so the UE will only need to monitor one paging occasion.

[0533] Step S1506: If SIM2 is registered through partial registration, a paging request is initiated in PLMN2 for SIM2 in UDM2, for example, based on a voice or IMS call associated with SIM2. UDM2 sends a paging request to the UE through AMF1 in step S1506 and identifies that the paging is associated with a temporary identifier assigned to SIM2 from PLMN2. The temporary identifier is provided to the UE at the end of the partial registration process. In addition, service prioritization information may be included in the paging request to inform the UE of the purpose of the paging and to help the UE decide whether to switch to PLMN2. The service prioritization information may contain a service type and additional information identifying the source of the data for which the UE is being paged. The service type may be a voice call, SMS message, other data (such as from an application), control plane signaling, emergency message, emergency callback, mobile terminated exception data, etc. The additional information may be the phone number of the caller or SMS message, a PDU session ID, a slice instance ID, or an application ID associated with the data. Alternatively, the additional information may be a prioritization level configured by the user of the multi-SIM UE. The paging request may be encapsulated in an encrypted NAS container so that only the UE can decrypt it, and may contain the contents of the NAS notification generated by PLMN2 for SIM2. The service type of the temporary identifier and possible service prioritization information may not be encrypted to allow PLMN1 to identify which UE to forward the NAS container to and provide the UE with some indication of what the paging is for. The contents of the NAS container in the paging request may also contain an SMS message, which can be sent to the UE without the UE connecting to PLMN2 to retrieve the message. If multi-SIM assistance information is provided to PLMN2, then PLMN2 may be able to determine whether to page the UE. For example, if the service prioritization information associated with paging as reflected in the multi-SIM assistance information is not configured as important to the user, then PLMN2 will not send the paging message shown in step S1506. In some cases, PLMN2 may be configured to forward a paging request message that includes only the UE identifier and service prioritization information. An example is that the user has configured that all paging messages should be filtered by the active PLMN, and therefore, all inactive PLMNs should forward paging requests with only the information required for the active PLMN to filter the paging request.

[0534] Step S1508: Alternatively, and in the case where SIM2 is registered through indirect registration, AMF2 may receive a downlink data notification for SIM2 and forward a paging to AMF1. The paging may include a temporary identifier associated with SIM2 from PLMN2, and a service type that may inform the UE what the paging is for and service prioritization information that the UE may use to determine whether to switch to PLMN2. At the end of the indirect registration process, the temporary identifier is provided to the UE. Similar to step S1506, the paging request may contain an encrypted NAS container with service prioritization information and an SMS message. Similar to step S1506, PLMN2 may use multi-SIM assistance information to determine whether to forward the paging message to PLMN1 and what information to include in the forwarded paging message.

[0535] Step S1510: AMF1 processes the paging request from either step S1506 or step S1508 and generates a NAS notification to the UE. The NAS notification may contain the temporary identifier of SIM2 and any service prioritization information provided. This notification may contain the encrypted NAS container received from step S1506 or S1508, so only the UE can decrypt the container and the SMS message (if it is provided). For the case where the UE is in CM-IDLE state, AMF1 generates a paging request message to page the UE.

[0536] Step S1512: AMF1 sends a paging to the UE via RAN1 using the temporary identifier associated for SIM2. In other words, and as an example, the ue-Identity of the PagingRecord information element of the paging message is set to the temporary identifier associated with SIM2 from PLMN2. The temporary identifier used can be any identifier specified in step S1504. In addition, the PagingRecord information element can be enhanced to provide the service prioritization information sent by AMF2 in step S1506 or S1508. The service prioritization information may include the service type (e.g., voice or IMS call, SMS message, other data for PDU session, control plane signaling, emergency message, emergency callback, mobile terminated exception data, etc.) and other information (such as PDU session ID or slice instance ID) to further inform the UE what the paging is for. For the case where the UE is in CM-CONNECTED state, AMF1 sends the NAS notification from step S1510 to the UE instead of a paging message. The NAS notification will contain the same information as the paging message used to generate the paging message when the UE is in CM-IDLE. Note that AMF1 will notify the RAN node to page the UE at the paging occasion associated with SIM1, but include the paging information associated with SIM2 received from PLMN2. In the case that AMF1 has assigned a separate temporary identifier for SIM2, AMF1 can notify the RAN node to page the UE using the temporary identifier assigned by AMF1 to SIM2, and the PagingRecord information element will contain the temporary identifier assigned by AMF1 to SIM2. If AMF1 assigns the same temporary identifier to all SIMs in the UE, then this temporary identifier will be used to page the UE.

[0537] Step S1514, the UE reads the paging message and determines that the paging is for SIM2 based on the temporary identifier in the ue-Identity information element of the paging message. The ue-Identity information element may contain one of the temporary identifier assigned by PLMN2 to SIM2 or the temporary identifier assigned by AMF1. If the temporary identifier is shared between all SIMs, the UE may need to perform a service request procedure to find out which SIM the paging applies to. The paging message may also contain an indicator that notifies the UE to perform a service request procedure to retrieve more information about what to do next. In the absence of an indicator, the UE may be configured to automatically perform a service request after determining that the paging is for the UE. If the UE is in CM-CONNECTED, the NAS notification is processed and the UE determines what to do next by evaluating the service prioritization information. If an SMS message is provided in a NAS container, the UE may also process the SMS message and present the message to the user. Therefore, the UE does not need to connect to PLMN2 to retrieve the SMS message.

[0538] Step S1516: If the UE is in CM-IDLE, the UE establishes an RRC connection for SIM1 with RAN1. The UE then performs a service request procedure with the core network to establish a NAS connection. The service request response may provide the UE with more information about what to do next and contains a temporary identifier for SIM2 from PLMN2 and service prioritization information. After evaluating the service prioritization information, the UE may decide to perform a SIM switching procedure to complete processing the paging and receive data associated with the paging from PLMN2. If the SMS message is provided in a NAS container, the UE may present the message to the user and does not need to connect to PLMN2 to retrieve the SMS message.

[0539] Fig.15 A situation is shown where the UE has an active registration on PLMN1, an inactive registration on PLMN2, and may receive paging requests for SIM2 forwarded from PLMN2. Conversely, the UE may be actively registered to PLMN2, have an inactive registration on PLMN1, and may receive paging requests forwarded from PLMN1. A requirement for forwarding paging requests from an inactive PLMN with which the UE has an inactive registration is that the UE performs a partial registration or an indirect registration with the inactive PLMN.

[0540] The service prioritization information may cover service types associated with services provided by the core network to the UE to receive downlink data, such as voice or IMS calls, SMS messages, other data (e.g., mobile terminated data, such as internet data), control plane signaling, emergency messages, emergency callbacks, mobile terminated exception data, etc. The service type prioritization information may also be associated with prioritized categories specifying the source of such services, such as PDU session ID, slice instance ID, application ID, calls or messages from family, friends or service providers, etc. Alternatively, the additional information may be a prioritization level configured by the user of the multi-SIM UE. The resulting enumeration combining the service type with the prioritized category may be presented in the PagingRecord information element of the paging message to give the UE additional information for making a handover decision. Alternatively, the service type may determine what paging channel is used to page the UE. In addition, in response to receiving a paging request, the UE may retrieve the service prioritization information. This service type prioritization information may be compared with the service prioritization list found in Table 2 to help the UE determine whether to switch to a service provided by the corresponding PLMN.

[0541] The multi-SIM paging operation describes the situation when the UE is in CM-IDLE under the active PLMN. However, if the UE is in CM-CONNECTED, then a different mechanism is required. In that case, when the UE is in CM-CONNECTED state, the active PLMN can send a NAS notification to the UE to inform the UE that there is pending data for the inactive SIM. This NAS notification can provide the same information as found in the paging message from PLMN2. In fact, this NAS notification can be used as a triggering event for paging the UE when the UE is in CM-IDLE state. In other words, whenever there is a paging request for the inactive SIM, the active PLMN can send a NAS notification to the UE in the CM-CONNECTED state. If the UE is in CM-IDLE state, then the NAS notification results in paging to the UE.

[0542] Multi-SIM paging operation is similar in LTE. As mentioned earlier, paging request forwarding allows a MUSIM UE to receive paging requests for secondary SIMs even if the UE is not actively monitoring paging occasions associated with those secondary SIMs. This feature is enabled by successfully performing the attach procedure mentioned above. Fig.28 In the scenario shown in , the UE is actively communicating with PLMN1 using the primary SIM, and there is data available for the secondary SIM on PLMN2. PLMN2 will forward the paging request for the secondary SIM to PLMN1, and PLMN1 will inform the UE that there is data for SIM2 on PLMN2. Fig.28 This scenario is shown when the UE is in ECM-CONNECTED state under PLMN1 for SIM1.

[0543] Step S2802: SIM1 and SIM2 are installed in the UE, where SIM1 is the primary SIM and SIM2 is the secondary SIM. The UE has performed a partial attach or indirect attach to the PLMN for SIM2, and paging request forwarding is enabled for SIM2. The EMM state for SIM1 in the UE is EMM-REGISTERED, while the EMM state for SIM2 is EMM-INACTIVE (or the "inactive registration" substate or mode of EMM-REGISTERED). The UE may provide multi-SIM assistance information to the PLMN for each SIM to configure the PLMN with respect to the user's preference for multi-SIM operation. The multi-SIM assistance information will be described in more detail below.

[0544] Step S2804: The UE is in the ECM-CONNECTED state for SIM1 and is receiving data service from PLMN1.

[0545] Step S2806: There is data available for SIM2 on PLMN2. If the UE has previously performed a partial attach, then the HSS in PLMN2 forwards the paging request to the MME in PLMN1 in step S2806a. If the UE has previously performed an indirect attach, then the MME in PLMN2 forwards the paging request to the MME in PLMN1 in step S2806b. The forwarded paging request indicates that there is data for the UE on PLMN2 and may include a temporary identifier assigned to SIM2, an identifier such as an application ID and / or PDU session ID associated with the data being paged, and additional information such as a service class indicating what the paging is for. The paging request may contain the content of a NAS notification generated by PLMN2 for SIM2 and encapsulated in an encrypted NAS container so that only the UE can decrypt it. The temporary identifier and possible service class may not be encrypted to allow PLMN1 to identify which UE to forward the container to and provide an indication of the service class for the paging. The content of the NAS container in the paging request may also contain an SMS message, which may be sent to the UE without the UE connecting to PLMN2 to retrieve the message. If the Multi-SIM assistance information is provided to PLMN2, then PLMN2 may use the information to determine whether to forward the paging message to PLMN1 and what information to include in the forwarded paging message.

[0546] Step S2810: The MME in PLMN1 generates a NAS notification including an encrypted NAS container according to the paging request received in step S2806.

[0547] Step S2812: The MME in PLMN1 sends a NAS notification to the UE. The NAS notification contains an encrypted NAS container sent from PLMN2, which notifies the UE that data is available for SIM2. This information may include a temporary identifier for SIM2, a service class associated with the data, and other information (such as an application ID and / or PDU session ID for the data). If an SMS message is provided in the NAS container, the UE can present the message to the user, so the UE is not required to connect to PLMN2 to retrieve the SMS message.

[0548] Step S2814: The UE checks the service category to check whether the UE should switch to PLMN2 to retrieve data. The service category can be classified into voice calls, SMS messages or other data (e.g., application data), control plane signaling, emergency messages, emergency callbacks, mobile terminated exception data, etc. The UE determines that the provided service category information requires a SIM switch request to be performed and proceeds to send the request to the MME in PLMN1. This request may be a registration update request or an enhanced TAU request, in which the UE provides a SIM switch indication to inform PLMN1 that the UE wishes to suspend the registration of SIM1 (e.g., set the UE state for SIM1 to EMM-INACTIVE). If the request is granted, the MME in PLMN1 sets the EMM state of SIM1 to EMM-INACTIVE (or enables the inactive registration substate or mode of the EMM-REGISTERED state), activates paging request forwarding for SIM1, and saves all UE contexts managed by PLMN1, including security contexts and existing PDN connections. After receiving the registration update or TAU accept response, the UE also sets the EMM state within the UE. Note that the SIM switching process may be initiated by the user through the GUI, by the application via the API, or by a policy for multi-SIM operation in the UE.

[0549] Step S2816: The MME in PLMN1 sends a paging request forwarding response to the MME or HSS of PLMN2, depending on the source of the original paging request from step S2806. The response may inform the MME or HSS of PLMN2 that the UE has decided to perform a SIM switching procedure and will connect to PLMN2 to complete processing the paging. The MME of PLMN1 may also inform the MME of PLMN2 that it has enabled paging request forwarding for SIM1. Alternatively, the response may include an indication that the paging is received but the user is not currently interested in connecting to PLMN2 to retrieve the data for the page. This may occur if the user is in the middle of an important call and does not want to be disturbed. The user may provide this indication through the GUI on the UE.

[0550] Step S2818: The UE then performs PLMN selection, reads system information, and performs cell selection for PLMN2 to attempt to connect to PLMN2. The UE may be configured to collect cell measurement information during this process to provide to the RAN node of PLMN2 after successful connection.

[0551] Step S2820: If the UE successfully connects to PLMN2, the UE sends a request (e.g., an Attach Request or a Service Request) to update the registration status for SIM2 and provide a temporary identifier assigned to SIM2 from one of the previously performed Attach procedures. In addition, the UE may include the identifier sent in step S2806 to indicate data associated with the paging from step S2806. If successful, the request will transition the EMM state for the UE in MME2 to EMM-REGISTERED (or the "inactive registration" substate or mode with EMM-REGISTERED disabled) and allow the UE to retrieve data related to the paging request sent in step S2806. The UE will also transition the internally saved EMM state to EMM-REGISTERED (or the "inactive registration" substate or mode with EMM-REGISTERED disabled) after receiving the response. The UE may also send the cell measurement results obtained from step S2820 to the RAN node of PLMN2. These measurement results may be used to assist the operator of PLMN2 in cell planning.

[0552] Although Fig.28 shows that when the UE is in the ECM-CONNECTED state for SIM1 in PLMN1, a paging request forwarding is sent, but Fig.29 The same scenario is shown but the UE is in ECM-IDLE state under PLMN1. In other words, the ECM state in both the UE and the MME of PLMN1 is ECM-IDLE. When in this state, the UE monitors paging information at the paging occasion associated with the temporary identifier assigned to the UE during the attach procedure.

[0553] Step S2902: SIM1 and SIM2 are installed in the UE, where SIM1 is the primary SIM and SIM2 is the secondary SIM. The UE has performed a partial attachment or an indirect attachment to PLMN2 for SIM2, and paging request forwarding is enabled for SIM2. The EMM state for SIM1 in the UE is EMM-REGISTERED, while the EMM state for SIM2 is EMM-INACTIVE (or an "inactive registration" substate or mode of EMM-REGISTERED). The UE may provide the PLMN with multi-SIM assistance information about each SIM to configure the PLMN with respect to the user's preference for multi-SIM operation. The multi-SIM assistance information will be described in more detail below.

[0554] Step S2904: Since the UE is in the ECM-IDLE state, the UE is monitoring the paging occasions associated with SIM1 and SIM2 in order to receive paging requests from both SIMs. Note that a temporary identifier for SIM1 and another temporary identifier for SIM2 may have been provided to the UE from the MME in PLMN1. Therefore, the MME may have assigned temporary identifiers in such a way that the paging occasions calculated according to each identifier overlap at the same time, which helps to minimize the time required for the UE to monitor paging requests. Therefore, the UE only needs to listen to one paging occasion. For the case where there are more than two SIMs, the MME may have assigned temporary identifiers so that the paging occasions do not conflict with each other. In these cases, the UE may have to monitor multiple paging occasions, but still be able to receive paging for all SIMs without encountering paging conflicts. In another case, the MME may have assigned the same temporary identifier to all SIMs in the UE, and this identifier will be used to calculate the paging occasions, thereby minimizing the number of paging occasions that the UE must monitor. In this case, the UE only needs to monitor one paging occasion and can receive paging for all SIMs installed in the UE.

[0555] Step S2906: There is data available for SIM2 on PLMN2. If the UE has previously performed a partial attach, then the HSS in PLMN2 forwards the paging request to the MME in PLMN1 in step s2906a. If the UE has previously performed an indirect attach, then the MME in PLMN2 forwards the paging request to the MME in PLMN1 in step S2906b. The forwarded paging request indicates that there is data for the UE on PLMN2 and may include a temporary identifier assigned to SIM2 from PLMN2, an identifier such as an application ID and / or PDU session ID associated with the data for paging, and additional information such as a service class indicating what the paging is for. The paging request may contain the content of a NAS notification generated by PLMN2 for SIM2 and is encapsulated in an encrypted NAS container so that only the UE can decrypt it. The temporary identifier and service class may not be encrypted to allow PLMN1 to identify which UE to forward the container to and provide an indication of the service class provided for the paging. The content of the NAS container in the paging request may also contain an SMS message, which may be sent to the UE without the UE connecting to PLMN2 to retrieve the message. If the Multi-SIM assistance information is provided to PLMN2, then PLMN2 may use the information to determine whether to forward the paging message to PLMN1 and what information to include in the forwarded paging message.

[0556] Step S2908: The MME in PLMN1 processes the information from the paging request received in step S2906.

[0557] Step S2910: The MME in PLMN1 sends a paging message to the RAN node in step S2910a with the temporary identifier assigned to the UE by the MME in PLMN1 for SIM2. The temporary identifier used may be any identifier specified in step S2904. The RAN node will then page the UE in step S2910b at the paging occasion that the UE is monitoring. Since the paging occasions for SIM1 and SIM2 are the same, the UE will receive the paging even though the paging is for SIM2. The paging message may also include service prioritization information to inform the UE of the purpose of the paging.

[0558] Step S2912: The UE then reads the paging report and determines that the paging is for SIM2 based on the service prioritization information and the presence of the temporary identifier assigned to SIM2. If the temporary identifier is shared between all SIMs, the UE may need to perform a service request procedure to find out which SIM the paging applies to. The paging message may also contain an indication informing the UE to perform a service request procedure to retrieve more information about what to do next. In the absence of this indication, the UE may be configured to automatically perform a service request when it is determined that the paging is for the UE.

[0559] Step S2914: The UE performs a service request procedure to retrieve more information on what to do next. After performing the SR procedure, the MME in PLMN1 may provide the UE with information from the forwarded paging request received from PLMN2. This information may include a temporary identifier associated with the paging, the service class of the paging, and other information received from step S2906.

[0560] Steps S2916-S2922: UE executes Fig.28 Steps S2814-S2820 in the process are performed to complete processing the paging, attaching to PLMN2, and receiving data associated with the paging request.

[0561] Fig.29 An alternative to step S2910a is for the MME of PLMN1 to send a paging request to the RAN node with a temporary identifier for SIM1 instead of a temporary identifier for SIM2. In this alternative approach, the paging message will contain the temporary identifier for SIM1 with an indication to inform the UE to perform a service request to obtain more information about what to do next. When the UE performs the service request procedure, the MME of PLMN1 provides information that the paging is for SIM2 and any additional information such as the service category of the paging. This alternative approach can be used if the MME of PLMN1 cannot provide a temporary identifier for SIM2 that aligns the paging occasions for SIM1 and SIM2 together. This is more difficult for situations where more than two SIMs are used. Alternatively, the MME of PLMN1 can assign the same temporary identifier to be used when paging all SIMs installed in the UE. In this case, the UE only needs to monitor one paging occasion and perform a service request procedure to find out which SIM the paging is for. The MME manages this by linking the registration status of all SIMs for the UE together and assigning the same temporary identifier for paging the UE regardless of the SIM.

[0562] For the case where the UE does not want to respond to paging, it can send a paging request without performing the SIM switching procedure. Fig.29 The paging request forwarding response shown in step S2918 of UE. This can happen when the user is in an important call and does not want to be disturbed. The user can provide this indication through the GUI on the UE. For these situations, when the UE is in Fig.29 The paging request forwarding response is sent after the service request process is performed in step S2914 of , but not after step S2916. The user may provide an indication that the paging is received but the user is not currently interested in connecting to PLMN2 to retrieve the paging data.

[0563] If the UE has been indirectly registered on the user plane, the paging request forwarding can also be sent via the user plane. Fig.40 An example is shown where a multi-SIM UE receives a NAS notification for SIM2 from PLMN2 via the user plane of PLMN1. The UE has performed an indirect registration for SIM2 to PLMN2 via the user plane of PLMN1, and downlink data arrives at AMF2 for SIM2.

[0564] Step S4002: The UE has performed an indirect registration for SIM2 with PLMN2 via the user plane of PLMN1. The indirect registration enables PLMN2 to forward paging requests for SIM2 to the UE via the user plane of PLMN1. The UE may provide the PLMN with multi-SIM assistance information about each SIM to configure the PLMN with respect to the user's preference for multi-SIM operation. The multi-SIM assistance information will be described in more detail below.

[0565] Step S4004: There is downlink data available for SIM2 on PLMN2 and AMF2 is notified. AMF2 can evaluate the available multi-SIM assistance information provided by the UE to determine whether the downlink data meets the paging filtering criteria. If the criteria are met, then AMF2 generates a NAS notification to send to the UE. Otherwise, AMF2 returns a response to the source of the downlink data, notifying the UE that it is not interested in receiving data at this time or that the UE is currently unavailable. The response may indicate that the data should be buffered. The NAS notification may include a PDU session ID or SMS message associated with the downlink data. Other events that may cause AMF2 to generate a NAS notification to the UE may be control plane signaling of a policy update that AMF2 wants to send to the UE. This may include reminders to perform periodic registrations or TAU updates, updates to URSP rules, new timer values ​​for the UE to use, how long the UE must respond to the notification, etc.

[0566] Step S4006: AMF2 sends a NAS notification to the UE via N3IWF2 over the user plane of PLMN1 in step S4006a. Depending on the connection management state of the UE, PLMN1 may send a NAS notification to the UE as a result of receiving a NAS notification from PLMN2, or if the UE is in CM_IDLE state, PLMN1 may page the UE. For PLMN1, the NAS notification from PLMN2 is mobile terminated data for the UE. Note that the NAS notification or paging sent by PLMN1 in step S4006b is associated with SIM1.

[0567] Step S4008: The UE evaluates the NAS notification received from PLMN1. Note that this NAS notification contains the information sent by PLMN2 in step S4006a. The NAS notification may contain service prioritization information to help the UE identify the service type associated with the data for which the NAS notification was generated in step S4006a.

[0568] Step S4010: The UE makes a service request in order to receive the mobile terminated data that caused the paging. If the UE determines that the service prioritization information in the NAS notification from PLMN2 sent in step S4006a is important, then the UE will then use one of two mechanisms to perform a service request to PLMN2. The first mechanism is that the UE continues to send a service request using the user plane of PLMN1 in response to the NAS notification received from PLMN2. If the UE wants to remain connected to PLMN1 and receive data for SIM2 through the user plane of PLMN1, then this mechanism can be used by the UE. The second mechanism is that the UE switches the connection to PLMN2 and establishes connectivity with PLMN2. If the UE is not currently receiving services on PLMN1 and wants to retrieve data associated with the NAS notification sent from PLMN2 and then continue to receive services from PLMN2 (for example, using SIM2 for calls), then the UE can use the second mechanism.

[0569] SIM Switching Process

[0570] If the UE receives a paging or NAS notification for a SIM of an inactive PLMN and the UE decides to retrieve data associated with the paging, the UE may perform a SIM switching procedure to notify the active PLMN to suspend the UE's registration state and allow the UE to establish communication with the inactive PLMN. Successful execution of the SIM switching procedure will transition the registration state of the UE's active SIM from RM-REGISTERED to RM-INACTIVE. Once in this state, the core network will retain all UE contexts, including existing PDU sessions and slice assignments, to allow the UE to quickly transition back to the RM-REGISTERED state. At this point, the UE will perform a periodic registration update for the inactive PLMN and transition its RM state under the inactive PLMN from RM-INACTIVE to RM-REGISTERED. The UE may then retrieve any data associated with the paging or NAS notification. Fig.16 FIG. 1 shows the SIM switching process performed by the UE when it switches from PLMN1 to PLMN2 due to receiving a paging message for SIM2. Note that Fig.16 The SIM switching process shown in uses 5G terminology, but the process is also applicable to LTE systems.

[0571] Step S1602: UE receives Fig.15 The UE receives the paging message described in and determines that the paging is for SIM2 based on the ue-Identity field of the PagingRecord information element. If temporary identifiers are shared between SIMs in the UE, the UE may not know which SIM the paging is for. In that case, the UE collects this information in step S1604 after performing the service request procedure. In addition, based on the new service prioritization field in the PagingRecord information element, the UE is informed that the paging corresponds to a voice or IMS call. The UE is configured to prioritize the voice or IMS call and decides to perform the SIM switching procedure. An alternative is that the user manually initiates the SIM switching procedure via the GUI, such as Fig.17 The paging message may also correspond to a notification or SMS message of downlink data availability for SIM2.

[0572] Step S1604: The UE establishes both RRC and NAS connections to be able to communicate with PLMN1. The UE may perform a service request procedure to retrieve information about which SIM the paging is for and possibly the service category of the paging. The UE may retrieve other information from the encrypted NAS container, such as the application ID, PDU session ID and / or slice instance ID associated with the data for the paging. The NAS container may also include (one or more) SMS messages for the paging. Based on this information, the UE decides to perform a SIM switching procedure. The decision may be triggered by the user through a GUI on the UE, or may be triggered by an application or policy on the UE.

[0573] Step S1606: The UE then performs a SIM Switch Request procedure, where the Registration Type is set to SIM Switch or a SIM Switch Indicator is included in the request. The SIM Switch procedure may be combined as a periodic registration update with a SIM Switch Indicator. This request is to inform PLMN1 that the UE wants to suspend its registration status and connect to PLMN2 to retrieve data associated with paging or use services provided by PLMN2.

[0574] Step S1608: AMF1 processes the request and updates the RM state of SIM1 to RM-INACTIVE. All UE contexts managed by PLMN1 (including existing PDU sessions) will be retained until the UE performs a registration update to transition back to the RM-REGISTERED state. Paging request forwarding is appropriately activated in UDM1 912 and / or AMF1 904, depending on whether a partial registration or indirect registration was performed previously.

[0575] Step S1610: AMF1 returns a registration suspension message to the UE with an indication that the UE's RM state for SIM1 has changed to RM-INACTIVE. Alternatively, the message may be a registration deactivation accept message. The message may include a registration timer value to indicate to the UE the duration that PLMN1 will maintain the RM state as RM-INACTIVE for SIM1.

[0576] Step S1612: The UE transitions its RM state from RM-REGISTERED to RM-INACTIVE for SIM1 and records the registration timer value if it is provided. In the absence of a registration timer value, the UE may use a value provided in an internal configuration within the UE policy or configured by the user in the GUI.

[0577] Step S1614: The UE performs PLMN selection, reads system information, and performs cell selection for PLMN2. The UE then performs a registration update procedure for SIM2 and may include a SIM switch indication. Upon receiving the registration accept message, the RM state for SIM2 in the UE will transition from RM-INACTIVE to RM-REGISTERED, and the UE will be able to receive voice or IMS calls from PLMN2.

[0578] Management of registration timer for inactive SIMs

[0579] After successfully performing the attach procedure for the secondary SIM, the UE may need to periodically notify the corresponding PLMN to update the registration timer in order to keep the EMM state in EMM-INACTIVE (or the "inactive registration" substate or mode of EMM-REGISTERED). To this end, the UE may request to update the registration timer on the secondary PLMN through the active PLMN, instead of disconnecting from the active PLMN and connecting to the secondary PLMN to perform the inactive registration timer update request. The UE may perform a single registration timer update request, which may be an enhanced TAU request that combines the update of the registration timers in the active PLMN and the secondary PLMN, such as Fig.30 Alternatively, if there is activity on the active PLMN that does not require a registration timer update, the UE may request the active PLMN to forward the Inactivity Registration Timer Update (IRTU) request solely to the secondary PLMN. Note that Fig.30 The process shown in is for an LTE system and the process can also be applied to a 5G system.

[0580] Step S3002: The UE sends a TAU request to the MME of PLMN1 to update the registration timer maintained in PLMN1 for SIM1. The request may include a temporary identifier assigned to SIM1 by PLMN1, a multi-SIM indicator, a temporary identifier assigned to SIM2 by PLMN2, and other parameters of the TAU request. This indicates to the MME in PLMN1 that not only the registration timer for SIM1 in PLMN1 is to be updated, but also the IRTU request for SIM2 is to be forwarded to PLMN2. Note that the multi-SIM indicator can be integrated into existing parameters (such as the preferred network behavior described above).

[0581] Step S3004: The MME of PLMN1 performs a TAU request for SIM1 and may assign a new temporary identifier to the UE for SIM1. HSS1 3002 may also participate in this step.

[0582] Step S3006: In addition, the MME of PLMN1 sends an IRTU request to the MME of PLMN2 to update the registration timer for SIM2. This IRTU request may include a multi-SIM indicator and a temporary identifier assigned to SIM2 by PLMN2. Note also that the MME of PLMN1 may provide location information of the last visited TAI parameter to convey the whereabouts of the UE so that PLMN2 can track the UE. Note that the IRTU request may be implemented as a TAU request or it may be an independent request.

[0583] Step S3008: The MME of PLMN2 performs an IRTU request for SIM2 and updates the UE context for SIM2 with the information provided in step S3006.

[0584] Step S3010: An IRTU Accept response with the requested status is returned to the MME of PLMN1, and a new temporary identifier (such as a GUTI) may be assigned to the UE for SIM2. New timer values ​​and other location related information, such as an updated TAI list, may also be provided. In 5GS, new UE policies may be provided in response to the UE. PLMN2 may also provide an indication that the registration status of SIM2 is no longer valid and the UE may need to re-register to PLMN2. This information may be provided within an encrypted NAS container so that only the UE can decrypt it.

[0585] Step S3012: The MME of PLMN1 aggregates the TAU Accept message with the IRTU Accept message and returns them to the UE. The response may include an encrypted NAS container with the information returned from PLMN2.

[0586] Step S3014: If a new temporary identifier is assigned to SIM1 or SIM2, the UE returns a TAU with an IRTU Complete message to the MME of PLMN1.

[0587] Step S3016: If a new temporary identifier is assigned to SIM2, the MME of PLMN1 forwards the IRTU Complete message received from the UE to the MME of PLMN2.

[0588] Provides cell measurement results obtained from the SIM switching process

[0589] There may be times when the UE attempts to perform a SIM handover procedure with an inactive PLMN and the UE is unable to establish connectivity with the cell of the inactive PLMN. The cell of the inactive PLMN may be overloaded or the UE may be in an area where there is a coverage gap in the inactive PLMN. In these cases, the UE may proactively provide the inactive PLMN with the measurement results found in the Minimization of Drive Test (MDT) report through the active PLMN, which may be used to improve cellular coverage. The measurement results may also be sent to the NWDAF in the inactive PLMN for analysis. Fig.31 A situation is shown where the SIM switching procedure fails for connection to PLMN2 and the UE reconnects PLMN1 to provide cell measurement results and cause codes forwarded to PLMN2. The forwarding of cell measurement results and cause codes may signal to the UE that paging cannot be processed further.

[0590] Step S3102: After receiving the paging or NAS notification, the UE performs a SIM switching procedure to disconnect from PLMN1 and attempt to connect to PLMN2. The UE may be configured to collect cell measurements while performing cell selection to attempt to connect to PLMN2. These measurements may then be saved and provided to PLMN2 in the future to help characterize the signal strength of various cells belonging to PLMN2.

[0591] Step S3104: The UE attempts to connect to a cell belonging to PLMN2, but the connection fails, possibly due to cell overload, relatively low cell signal power making it difficult to maintain a connection, or even a nearby cell that does not provide coverage for the UE. At the same time, the UE collects cell measurements during this process and a cause code from the RAN2 node 906 indicating that the UE failed to connect to the cell may be provided to the UE. For the case where there are no available cells, the UE may be configured with a cause code indicating this. It is also noted that the failure may originate from the MME and a corresponding cause code may be returned from the MME to the UE.

[0592] Step S3106: Unable to connect to the cell belonging to PLMN2, the UE reconnects to the cell belonging to PLMN1.

[0593] Step S3108: The UE then sends a SIM switch request to the MME of PLMN1 and provides the cell measurements collected for the cells of PLMN2. These measurements may be provided in an encrypted NAS container so that only PLMN2 can decrypt. An indication may be provided to inform the MME of PLMN1 that there is data to be forwarded to the MME of PLMN2. A reason code may also be provided as the reason why the UE was unable to connect to the cell belonging to PLMN2. This reason code may be used to inform PLMN2 that the UE attempted to complete processing the paging request but was unable to establish a connection with the cell of PLMN2. Additionally, an ... Fig.28 In step S2806, PLMN2 is provided with an identifier associated with the paging to inform PLMN2 that the UE cannot retrieve data belonging to this paging.

[0594] Step S3110: The MME of PLMN1 processes the SIM switch request to re-enable the UE context stored in the MME for SIM1, set the EMM state to EMM-REGISTERED (or disable the "inactive registration" substate or mode of the EMM-REGISTERED state), and deactivate paging request forwarding for SIM1.

[0595] Step S3112: The MME in PLMN1 receives the encrypted NAS container from the UE together with Fig.28 The UE forwards the identifier and cause code associated with the paging received in step S2806 to the MME in PLMN2. This step is conditional and only occurs if the UE has previously performed an indirect attach with PLMN2 for SIM2.

[0596] Step S3114: A response is returned to the UE to indicate the SIM switching status for SIM1 under PLMN1. The response may indicate the cause code and the status of the forwarding of the cell measurement result to PLMN2.

[0597] Intercommunication with multi-SIM UE

[0598] Multi-SIM UEs can support connectivity with both LTE and 5GS networks. It should be understood that the enhancements proposed herein can be applied to interworking scenarios involving UEs switching between LTE and 5G and switching from 5G back to LTE. Fig.32 The non-roaming interworking architecture between 5GS and EPS is shown, where the N26 interface connects the MME in LTE to the AMF in 5G. In addition, the HSS+UDM 3204 is connected to the MME and AMF via interfaces S6a and N8, respectively. These interfaces can be used to support the attachment process and the paging request forwarding function proposed in this article.

[0599] Impact of multiple SIM cards on 5G UE strategies

[0600] Currently, the UE policies stored in the UE include ANDSP and URSP policies to assist the UE in making access network and user routing selection decisions respectively. The UE policy is delivered to the UE by the PCF via AMF and NAS messaging. In order to support multi-SIM UEs, it is proposed to introduce a new policy type for UE policy - multi-SIM policy. This new policy will define various aspects of the operation of a UE with multi-SIM capabilities. An example of the proposed multi-SIM policy is shown in Table 2.

[0601] Table 2 – New multi-SIM policies in UE policy

[0602]

[0603]

[0604] Some of the information in the multi-SIM policy may be pre-provisioned to the UE, or determined by the UE, configured by the user via the GUI, obtained by the UE from the core network, or a combination thereof. New multi-SIM policies may be created manually by the user, or dynamically by the UE for each installed SIM. A list of multi-SIM policies may then be presented in the GUI, such as Fig.17 as shown in .

[0605] Alternatively, the multi-SIM policy can be created by the core network after the UE successfully registers to a PLMN. The multi-SIM policy sent by the PCF to the UE can be PLMN-based. In other words, the PCF in each PLMN with which the UE communicates can send the multi-SIM policy to the UE. Then when the UE registers to other PLMNs, the new multi-SIM policy is added to the UE's policy, and Fig.17 The GUI shown in may summarize all PLMNs to which the UE is registered. The user may then assign a priority to each PLMN and manually configure other parameters associated with that PLMN. Receipt of a new multi-SIM policy may trigger the UE to attempt a partial or indirect registration procedure as described earlier in this disclosure.

[0606] The UE may provide the core network with the UE's radio capabilities to assist the network in improving multi-SIM operations. Knowing the UE's radio capabilities may enable the core network to adjust the paging strategy used to ensure that the UE is able to receive paging requests while also minimizing the use of network and paging resources. The UE may have single Rx, single Tx capabilities, which indicates that the UE can only receive downlink signaling for one SIM at a time and can send uplink signaling for one SIM to the network at a time. A UE with dual Rx, single Tx capabilities may receive downlink signaling from up to two SIMs at a time, but can only send uplink signaling for one SIM at a time. The core network may provide the UE with a multi-SIM strategy based on the UE's radio capabilities during registration. This can help ensure consistent network operation for multi-SIM UEs and help the network manage paging resources more efficiently. For example, the network may adjust the paging occasion for a single Rx UE by sending UE paging area information for a specific SIM. Upon receiving the paging area information, the UE may compare the received paging area with the paging area of ​​another SIM to determine if there may be a potential paging conflict. If there is a potential paging conflict, the UE may request another paging occasion for the SIM from the core network.

[0607] Instead of the UE radio capabilities being included as part of the multi-SIM policy, it can be a separate indicator provided by the UE to the core network during registration. The presence of this indicator allows the core network to manage the paging occasion assignment based on the UE's radio capabilities. For UEs with dual Rx capabilities, the core network can assign a temporary identifier associated with a random paging occasion. For UEs with single Rx capabilities, the core network can use the multi-SIM assistance information as described below to adjust the paging occasions of different SIMs to avoid paging conflicts.

[0608] Within the multi-SIM policy, a service prioritization list may be configured by the user of the multi-SIM UE to indicate the priority of multi-SIM traffic, such as which is the primary SIM, which types of services have a higher priority and the network should page the UE, which types of services have a lower priority and the network should not page the UE, duration, location information, etc., where the UE should prioritize traffic from a specific SIM, etc. The multi-SIM assistance information utilizes the user preferences from the service prioritization list and provides additional information to assist the core network in how to enhance or optimize network operations for multi-SIM UEs. The assistance information may inform the core network which traffic is important to the UE and therefore pages the UE, which traffic is not important to the UE and should be ignored by the network by not paging the UE, how the network may assign new temporary identifiers to avoid paging conflicts and which parameters to use when assigning new parameters, how long filtering of paging requests is enabled by the core network, etc.

[0609] The information presented in the service prioritization list can be used to assist the UE in determining what to do when receiving the service type information in the paging request. The service type information can provide high-level information such as voice call, SMS message, other data, control plane signaling, emergency message, emergency callback, mobile termination exception data, etc. The UE can check whether the service type provided in the paging request matches the service type in the service prioritization list. If there is a match, the UE can decide to perform a SIM switching process to retrieve data associated with the paging. However, if the service type provided in the paging request is not found in the service prioritization list, the UE can respond to the paging that it is currently busy and can also enable paging request filtering.

[0610] In some cases, the UE may want more granular information about what the paging is for in order to make better decisions. For example, a call from a family member or close friend may be of more interest to the user than a call from a telemarketer or robot caller. Therefore, prioritization level information may be included in the service prioritization list to specify a finer granularity of services that the user is interested in. This information may be provided by the user configuration via the GUI after multiple SIMs are initially installed in the UE. The user may group users such as family members, friends, colleagues, acquaintances, contractors, etc., and assign priorities only to certain groups, such as family and friends. Alternatively, the groups may organize the priority levels as numbers, such as level 1, 2, 3, etc.

[0611] The service prioritization list may include the service type category and service prioritization level as shown in Table 3, so that the UE can determine whether paging is important to the user. The service type category may include voice call, SMS message, other data, control plane signaling, emergency signaling, emergency callback, mobile terminated abnormal data, etc. Different priorities may be provided for each service type. For example, levels such as level 1, 2, and 3 may be assigned for voice call and SMS message to specify whether the call is from the user's family and friends, from the user's contact, or for a call from a source other than the user's contact. Similarly, for other data and control plane signaling for UE and other indications for describing emergency signaling, high and low levels may be assigned. One level may exist, such as in the case of emergency callback and mobile terminated abnormal data. Both of these situations may refer to the situation where the core network has important data for the UE.

[0612] Table 3 Service Prioritization List Information

[0613]

[0614] As previously described, the service type category and service prioritization level may be included in the paging message received by the UE. Using the service prioritization list configured by the user, the UE can then use the service type category and prioritization level to determine whether the data associated with the paging is of interest to the user and help the UE decide how to respond to the paging. For example, the UE may decide that the data associated with the paging is important to the user and decide to perform a SIM switching procedure. Conversely, the UE may decide that the data is not so important to the user and notify the PLMN that the UE is busy or cannot be reached. In other cases, the UE may present the service type and prioritization level information to the user via a GUI and let the user decide how to proceed.

[0615] Before the UE registers, some of the service prioritization levels may not be readily available to the network, such as the prioritization levels for voice calls and SMS messages. After the UE registers, groups of these levels with appropriate contacts can be provided to the network by the UE via an application server. This can be done by an API exposed to the application server that allows the user to configure different priority levels (as indicated in Table 3). Alternatively, the user can dynamically provide this information during the service request process or through the user plane by marking the service with the appropriate level. For example, the GUI can prompt the user to associate what priority level with the phone number after a voice call. The UE can then signal the indicated priority level of the voice call to the core network via the user plane.

[0616] Once the user has configured the service prioritization list, the UE may utilize the user preferences to derive Multi-SIM assistance information for the Multi-SIM policy to provide to the core network. The Multi-SIM assistance information may provide the core network with a set of service types and priorities on which to filter paging to the UE in order to minimize waste of network and paging resources. Additionally, other information in the Multi-SIM assistance information may be provided to request different paging occasions that the UE monitors between installed SIMs to better avoid paging conflicts. The assistance information may be configured by a network policy sent to the UE and will be described in more detail below.

[0617] The multi-SIM assistance information may be provided to the core network initially during registration or as needed when the UE detects a need to notify the core network of such information. For example, when a user of the UE requests to use a service for a specific SIM for a certain duration (such as an important voice call), the UE may provide the multi-SIM assistance information in a service request or in a registration update request. The core network may then use the assistance information to filter paging for services that the user is not interested in, and only page the UE for more important services. Similarly, after the user completes a voice call, the UE may remove or disable the assistance information to enable the core network to page the UE for all services.

[0618] Fig.41 An example of how a multi-SIM UE provides the core network with user configuration and the user's preferences for how the UE behaves for multi-SIM operation is shown. After multiple SIMs are installed into the UE and the UE is powered on, the GUI prompts the user to configure the preferences that the UE follows. When the user completes the configuration, the UE performs registration for each SIM installed in the UE. Fig.41 The registration of one of the SIMs is shown and how the user configuration is sent to the core network in the form of a multi-SIM policy.

[0619] Step S4102: A user installs multiple SIMs in the UE, and after power-on, the UE prompts the user via the GUI to configure information for multi-SIM operation. The information provided by the user may be used to specify the user's preferences for how the UE manages multi-SIM operation on the UE. These preferences may be obtained in the service prioritization list of the multi-SIM policy shown in Table 2. The UE may then add the user preferences to the multi-SIM policy and provide the policy to the CN to enable enhanced handling of multi-SIM services. In addition, the UE may provide information to which it may have access, such as SIM identifiers, PLMN IDs and names, UE radio capabilities, the maximum number of SIMs, and a PLMN list, to derive a multi-SIM policy.

[0620] Step S4104: After the user has configured the service prioritization list, the UE sends a registration request with the multi-SIM policy shown in Table 2 to the RAN node, which includes a multi-SIM indicator and multi-SIM assistance information in combination with the user configuration. The multi-SIM indicator and multi-SIM assistance information may also be included in the access layer message so that the RAN node can read the indication and information and take them into account during AMF selection.

[0621] Step S4106: The RAN node then selects an AMF that supports multi-SIM UEs based on the presence of the multi-SIM indicator.

[0622] Step S4108: The RAN node forwards the registration request together with the multi-SIM indicator, multi-SIM assistance information and the remaining information elements of the multi-SIM policy to the selected AMF.

[0623] Step S4110: AMF performs the UE registration and authentication process from TS23.502 [2]. During this process, the AMF and PCF may provide additional information to the multi-SIM policy. The AMF may provide (one or more) temporary network identifiers and registration timer values, while the PCF may provide whether the network supports dual RM-REGISTERED operation. Dual RM-REGISTERED support indicates that the network is able to link multiple SIMs from the UE together and provide optimization for multi-SIM operation. For example, if the UE requests such a change, the network may be able to reassign a temporary UE identifier to change the associated paging occasion. This support may also include forwarding paging requests from one SIM to the paging occasion of another SIM and other multi-SIM enhancements described in this disclosure.

[0624] Step S4112: The AMF returns a registration accept response to the UE and includes the update of the multi-SIM policy performed in step S4110.

[0625] Step S4114: The UE internally updates the multi-SIM configuration based on the updated multi-SIM policy received from step S4112. The UE may present the policy to the user via a GUI showing all updates to the multi-SIM policy and prompt the user to confirm the updated policy.

[0626] Step S4116: If the user is prompted and confirms the multi-SIM policy, the UE may return a registration complete message to the AMF. If the UE detects the possibility of paging conflicts between multiple SIMs based on the paging occasions of each SIM, the UE may return an indication in the registration complete message to request the AMF to assign new temporary identifiers corresponding to different paging occasions to avoid paging conflicts. The UE may provide other multi-SIM assistance information as described below to assist the AMF in assigning new temporary identifiers.

[0627] It is noted that the inclusion of the Multi-SIM policy may be provided during any registration procedure, whether it is an initial registration, periodic registration update, partial registration, indirect registration, etc. For situations where the UE is not able to provide the entire Multi-SIM policy to the network, components of the Multi-SIM policy, such as Multi-SIM assistance information, may be provided separately to the core network. Furthermore, the Multi-SIM assistance information may be signaled to the core network any time the UE wants to request special handling for Multi-SIM services. This may include adding the Multi-SIM assistance information to a service request or a PDU session establishment or modification procedure. The Multi-SIM assistance information may be provided during a SIM switching procedure to inform the core network how to filter paging requests during times when the UE is not in the network.

[0628] For LTE, multi-SIM assistance information can be implemented as context information maintained internally in both the UE and the MME. Table 4 shows an example of adding a service prioritization list and multi-SIM assistance information to the UE's information storage stored internally as a UE context. This information can be included in the attach process when the UE initially registers to the core network, or they can be provided in the service request as needed to dynamically enable paging request filtering. Similarly, the MME can store the assistance information in the mobility management context for each multi-SIM UE. If necessary, some of the multi-SIM assistance information can also be stored in the HSS.

[0629] Table 4 Multi-SIM assistance information added to UE context for LTE

[0630]

[0631]

[0632] Multi-SIM UE support for MNOs without coordination

[0633] Although the solutions mentioned earlier in this disclosure solve the paging conflicts caused by two or more SIMs, these solutions do require some coordination between MNOs. In some deployments, there may be no coordination between MNOs, for example, there is no signaling between network functions of different MNOs (such as between AMFs or MMEs of different MNOs). For these situations, other solutions are proposed below to solve the problem of paging conflicts faced by multi-SIM UEs. However, it is noted that certain aspects of the described solutions mentioned above may be applicable to the non-MNO coordination situation considered below. For example, the solution in which the core network assigns temporary identifiers to multiple SIMs in the UE whose paging occasions are aligned is still applicable. This will be explained in detail when re-introducing the multi-SIM indicator presented below. The solution described below also applies to the case where there is MNO coordination. As an example, for the case where there is MNO coordination, the paging criteria described below can also be used in the registration process. The paging criteria can be used by the core network to determine whether to page the UE after receiving a forwarded paging request. Finally, it is expected that although the following solutions are described for 5GS, they can also be applied to LTE systems with relevant changes to network entities, process names, etc.

[0634] Even if there is no coordination between MNOs, it is still advantageous for the network to be aware of the multi-SIM UE to avoid degrading network performance when the UE switches communications to another MNO after communicating with the current MNO. As mentioned earlier, network operations are based on timers and algorithms that rely on knowledge of the UE state in order to operate efficiently. When the network does not know what the UE is doing, these timers and algorithms do not work as expected, which degrades network performance. Therefore, it is also important that the multi-SIM UE informs the network of its capabilities when registering to the network and also when it will be temporarily unavailable (for example, when the UE decides to switch the connection to another MNO). Temporarily unavailable in this context refers to the fact that the UE is planning to switch to another MNO and will not be able to monitor paging occasions. Therefore, the UE is temporarily unavailable until it switches back to the current MNO. The following solution addresses the case where there is no MNO coordination and focuses on how the UE can help minimize the occurrence of paging conflicts. Note that some aspects of the solution may apply to the single-MNO case, where both SIMs belong to the same MNO, while other aspects may apply to dual-Rx, single-Tx capable UEs.

[0635] UE Registration and Multi-SIM Assistance Information

[0636] The UE to core network registration process configures certain parameters between the UE and the CN so that the UE can receive the services for which it is registered. There are many variations of the registration process, from initial registration to mobility registration update, to periodic registration update, and to emergency registration. These processes provide information to the CN to configure the parameters that the UE and CN use to communicate with each other. For example, DRX parameters help define a discontinuous reception cycle in which the UE turns on for certain periods of time to monitor for paging requests and turns off for some other durations to help conserve battery power.

[0637] Certain additional parameters are proposed to be added to the registration process so that the UE can provide information to the core network to help avoid paging conflicts. These new parameters are summarized in the list below and may be grouped together and referred to as Multi-SIM Assistance Information. Multi-SIM Assistance Information may be provided to the core network during the registration process to enable the core network to better handle multi-SIM traffic by adjusting the paging strategy to minimize the waste of network and paging resources, especially during the time when the UE is in a pending registration state.

[0638] Paging criteria: criteria that specify certain conditions that the network uses to page the UE when the conditions or events for paging are met. The UE can derive paging criteria based on the user configuration found in the service prioritization list, and the paging criteria can consist of a list of service type categories and priority levels. The UE provides this parameter of the criteria to the network for use when attempting to page the UE. This criterion can be provided by the UE to trigger the CN to filter certain pages when the UE is not actively monitoring the PO due to being connected to another MNO to serve another SIM. For example, the above service categories can be used for the UE to configure the network to filter the paging criteria for which paging requests are sent. If additional information is provided, such as the user phone number, PDU session ID, and application ID, the filter can be more refined. Examples can include, for example, phone calls with associated phone numbers, text messages associated with users, or other data (e.g., Internet data) services associated with PDU session IDs or application IDs. Alternatively, the additional information can provide various priority levels for each service type. The criteria may be a whitelist including different combinations of service categories, such as calls from family, texts from family and best friends, and other data (e.g., Internet data) from a certain PDU session ID. Based on these criteria, the core network will page the UE only when the downlink data meets one or more of these criteria, thereby saving paging resources for data that the user is not interested in. In addition, the paging criteria may include criteria such as UE status, location information, and duration when paging request filtering is applicable.

[0639] Restricted Paging Area: For situations where the UE is connected to another MNO and cannot respond to paging, the UE can request to restrict the paging areas to which the CN sends paging messages. This parameter can be specified so that the network only pages UEs within the registration area or the last tracking area where the UE is located. This parameter can even specify the number of times the network attempts to page the UE before stopping paging. This can help reduce the waste of paging resources in network cells outside the UE's current tracking or registration area. The CN can determine the UE's tracking and registration area when it receives a mobile registration update that includes this indication, which the UE can provide to indicate that it can switch the connection to another MNO.

[0640] · Paging Occasion Separation: The UE may provide this parameter to configure the required PO separation when the UE requests a new temporary identifier (and associated PO) based on the detection of a potential paging conflict. The UE may provide this parameter to request the network to provide a new temporary identifier, where the associated PO is a certain distance in time from the currently assigned PO, for example, based on the spacing of the number of paging frames, time slots, etc., or the parameter may represent a descriptive enumeration (such as "far apart", "close together" or "different") to give the network flexibility in assigning temporary identifiers. The request for different paging occasions may be an indication that the UE expects paging occasions to occur with the same periodicity but at different times. Therefore, it may be an indication that different offsets are expected.

[0641] Number of missed pages before notification: This value determines the threshold at which the CN detects that the UE has missed receiving a page before notifying the UE. The UE may configure this value during initial registration when the UE also notifies the CN that it is a multi-SIM device. Alternatively, the value may be operator configured, either by operator policy or by commands received from the operator's operations and management applications.

[0642] ·Multi-SIM indicator: The UE may also provide a multi-SIM indicator similar to the multi-SIM indicator described above, but in this case the resulting functionality may be different. In this case, the multi-SIM indicator may cause the CN to configure one or more of the above parameters and provide the UE with a new temporary identifier that meets those criteria. In the case where both SIMs belong to the same MNO, the registration request may also contain an identifier of the other SIM, such as an IMSI or 5G-GUTI, to inform the core network that the UE supports multiple SIMs and possibly provide certain network optimizations related to registration of multiple SIMs. Utilizing the multi-SIM indicator and the identifier of the other SIM, the core network may be able to assign a temporary identifier to the current SIM whose paging occasions are aligned with the paging occasions of the other SIM as described above. Thus, the paging occasions for the two SIMs in the UE are aligned, and the UE will only need to monitor one paging occasion.

[0643] Proposed Temporary Identifier: The UE may use this parameter to propose a temporary identifier that it determines will avoid paging conflicts with another SIM's PO. Again, the UE may be able to propose a temporary identifier whose paging occasions align with the paging occasions of another SIM in the UE. Alternatively, the UE may propose a portion of the temporary identifier (e.g., the portion used to calculate the paging occasions) and the network may assign the rest of the temporary identifier.

[0644] The UE may provide these parameters at initial registration to initialize the parameters used by the CN when generating certain settings. Similarly, the UE may also include these parameters within, for example, a mobility registration update or periodic registration update procedure, after the UE has determined that there is a potential paging conflict between the POs of the two SIMs and is requesting a new temporary identifier (and associated PO) from the CN. While the description has indicated that the UE provides the proposed parameters to the CN, it is to be understood that these parameters may also be configured by the CN, for example as part of an operator policy. Fig.34 The UE is shown requesting a new temporary identifier and associated PO from the CN using the Mobility Registration Update procedure. Note that the terms PLMN1 and PLMN2 are used to represent uncoordinated MNOs to be consistent with other figures in this disclosure.

[0645] Step S3402: The multi-SIM UE first registers with PLMN1 and receives a temporary identifier for SIM1. The UE then registers with PLMN2, possibly after disconnecting from PLMN1. The UE receives a temporary identifier for SIM2.

[0646] Step S3404: The UE uses the temporary identifier to calculate the paging occasion associated with each SIM. Based on the timing information that the UE has for each PLMN, the UE detects that there may be a paging conflict, such as Fig.35 Although the timing relationship between the PLMNs is asynchronous, the UE may be able to detect paging conflicts by superimposing the two timing references together to obtain a single timing reference. Fig.35 The paging frames associated with each PLMN are shown, and even if their superframe timing is not aligned, their paging occasions will overlap. Note that the POs may not necessarily need to overlap to cause a paging conflict. If the POs are close enough to each other, this will also cause a paging conflict because the UE does not have enough time to switch the connection from one PLMN to another. Each time the UE has to perform this operation, there is some latency associated with the process, for example, the UE must tune the radio to the appropriate frequency, perform a cell search, PLMN selection, etc.

[0647] Step S3406: Once the UE detects that there is a possibility of a paging conflict, the UE can then request another temporary identifier from one of the PLMNs that will generate a paging occasion different from the current paging occasion. The UE can send a mobility registration update and include the proposed parameters listed above (such as PO separation). The UE can also configure the PLMN to page the UE only for certain data (such as voice calls and SMS messages) by using paging criteria parameters. In addition, the UE can configure the CN to limit the paging area to the last tracking area or registration area that the UE contacted the CN to minimize the waste of paging resources in other tracking or registration areas. The UE can also only include a multi-SIM indicator to let the CN provide a new temporary identifier corresponding to another PO, or even propose a new temporary identifier whose PO location is different from the current PO. The UE may have discovered that the CN supports the multi-SIM feature because it was pre-provisioned with information, received information in a previous registration accept message (such as information provided in a multi-SIM policy), or by reading system information.

[0648] Step S3408: The AMF returns a registration acceptance message, which may include a new temporary identifier. The new temporary identifier may correspond to another PO that is located at a different location than the previous PO. The UE then checks the timing of the new PO with the PO of another SIM to ensure that there is no possibility of a paging conflict. If the UE still detects a paging conflict, the UE may repeat step S3406 to obtain another temporary identifier. This time, the UE may use different values ​​of the previously sent parameters to try to obtain a temporary identifier with a different PO that will not cause a paging conflict. Alternatively, the UE may propose a temporary identifier that it has determined will avoid paging conflicts with POs of other PLMNs.

[0649] The paging criteria may be provided by the UE at one of the registration procedures to configure the CN to filter when to page the UE when the UE has activated the registration suspension timer, which is described in more detail later. This criterion may be sent during the initial registration to statically configure the CN, or sent during the mobility or periodic registration update procedures to dynamically configure the CN regarding the UE's preferences in the CN filtering paging requests. Alternatively, the criterion may be provided in a service request when the UE wants to notify the network that it is busy and stop paging the UE for a certain duration. For example, the criterion may be a whitelist or blacklist of service categories / prioritizations that the UE wishes the CN to filter when deciding to page the UE. For example, the criterion may also include more granular information included in the paging message, such as a phone number, PDU session ID, and application ID.

[0650] Paging criteria can be used in a UE with dual Rx, single Tx capability to allow the CN to page the UE for important data that the user may want to be paged for. This can reduce the overhead of the UE responding to pages that the UE may not be interested in. For example, in a business / personal subscription use case, on weekends users may only want to receive calls from their boss and team members and not receive calls from others. Paging criteria can be set before the weekend starts to allow calls only from these people. Conversely, the user may want to preempt receiving pages and set the paging criteria to not page the UE for all business.

[0651] Request for multiple paging occasions

[0652] Since the timing relationship between cells of different MNOs is asynchronous and can vary from cell to cell, having a single PO can cause paging conflicts on one cell but not on another. For these cases, it may be better to provide the UE with multiple POs and allow the UE to listen to a PO that does not conflict with another SIM's PO. In this case, the UE can dynamically decide which of the multiple POs to listen to for a paging request based on its internal timing for each MNO. This option can be used in cases where the single PO use case still results in paging conflicts.

[0653] To request multiple paging occasions, the UE may include a multiple PO indication in one of the registration requests, such as a mobility registration update or a periodic registration update procedure. The indication may specify the number of desired temporary identifiers to be assigned to the UE, or simply a flag that the UE requests multiple temporary identifiers and has the core network provide however many temporary identifiers to the UE. The UE may combine any other parameters described herein to assist the core network in assigning temporary identifiers corresponding to desired PO characteristics. For example, a paging occasion separation parameter may be used to indicate a desired separation between multiple POs.

[0654] Once the UE receives the temporary identifier associated with the PO, the UE will decide which PO to monitor based on the PO it has for the other SIM. Therefore, as the UE moves from one cell to another, if the PO for either SIM shifts, the UE is able to dynamically decide which of the multiple POs to monitor to avoid paging conflicts. Once the UE responds to the paging, the network can stop paging the UE on other POs assigned to the UE. The UE can request multiple temporary identifiers from each MNO to give maximum flexibility to avoid paging conflicts. For example, the UE can request two temporary identifiers from MNO1 and MNO2 respectively and request the desired PO separation, and the UE will be able to avoid paging conflicts between the four assigned POs regardless of mobility.

[0655] The restricted paging area parameter may be used in conjunction with a request for multiple paging occasions to offset the paging resource overhead introduced by having multiple paging occasions. As previously described, the restricted paging area parameter may specify that the CN restrict the area in which it pages the UE to the last known tracking or registration area of ​​the UE. This parameter may be used to limit paging escalations that may occur, where the CN expands the area in which it pages the UE if the UE does not respond to paging. Since the UE is already requesting multiple POs, adding the restricted paging area parameter may concentrate the paging overhead to the tracking or registration area in which the UE last communicated with the CN, thereby saving paging resources in other tracking and registration areas.

[0656] Simultaneous paging at the same paging occasion

[0657] For situations where the SIMs belong to the same MNO and the CN assigns temporary identifiers to the SIMs to correspond to the same PO, there may be situations where data is available for both SIMs simultaneously and then the CN pages the UE. During these situations, the paging record of the paging message will contain a UE identifier that matches the UE identifier of the temporary identifier of each SIM. For the UE, the question that arises is for which SIM to complete the processing of the paging request.

[0658] This problem can be easily solved by enabling the UE to include a list of PDU session IDs corresponding to the two SIMs in a service request sent to the CN in response to a paging request. To this end, it is proposed to include a new parameter in the service request, which contains an identifier of the other SIM and another PDU session list parameter to be activated. The new parameter can be added to the existing parameter list used for the service request process so as not to interfere with the existing operation. Therefore, the service request will provide information about one SIM using the existing parameters and information about the second SIM with the new parameters. Including multiple instances of this new parameter can be used to extend support to multiple SIMs, where multiple refers to three or more SIMs. The benefit of adding the new parameter to the service request process is to save paging resources, where the service request notifies the CN to stop paging the UE for data associated with two or more SIMs.

[0659] For a more integrated solution, the list of temporary identifiers and PDU Sessions to be activated can be combined together and the combined list can be specified in the service request procedure. In this case, the new parameter can be considered as a list of key-value pairs; the key part containing the temporary identifier associated with the SIM and the value part containing the list of PDU Sessions to be activated. This solution is more scalable because the list can be extended to include as many SIMs supported by the UE without changing the structure of the message format.

[0660] Registering a Suspend Timer

[0661] The operation of a multi-SIM UE may be programmed such that the UE periodically switches connections between PLMNs in order to serve each SIM installed in the UE. Taking this mode of operation as an example, it is proposed that the core network supports a mechanism in which the UE can request the suspension of a registration timer maintained by the CN for the registration state of the UE. Instead of introducing a new registration state as described above, a new registration suspension timer may be introduced. The operation of the registration suspension timer may be mutually exclusive with the operation of the current registration timer. For example, when the UE requests activation of the registration suspension timer, the registration timer maintained by the CN is suspended. This occurs when the UE performs a mobility registration update or a periodic registration update and includes a registration suspension indicator to activate the suspension timer. An alternative is that the timer may have a dual operation mode, with an indicator to show which mode is currently in operation.

[0662] The UE may provide a value for the Registration Suspend Timer to reflect the periodic duration that the UE expects to be connected to another PLMN. This value may be included in a Mobility Registration Update or a Periodic Registration Update to cause the CN to suspend the Registration Timer. Upon receiving this value, the CN may suspend the Registration Timer and activate the Registration Suspend Timer. Then after a period of time, the UE may go back and deactivate the Registration Suspend Timer and re-enable the Registration Timer. Fig.36 An example of this process of activating and deactivating the registration pending timer is shown.

[0663] Step S3602: The multi-SIM UE is registered to both PLMN1 and PLMN2. Currently, the UE is actively communicating with PLMN1.

[0664] Step S3604: The operational programming logic of the UE decides to switch the connection from PLMN1 to PLMN2. The UE sends a mobility registration update or periodic registration update request to the AMF in PLMN1. This request includes an indication to activate the registration suspension timer, or it may include the expiration time of the registration suspension timer. The value of the expiration time may be configured within the operational parameters of the UE, a policy maintained by the UE or configured by the core network, or some other operational metric programmed by the user through the GUI. The UE may also provide an indication to request the CN to queue any downlink data for the UE while the registration suspension timer is running.

[0665] Step S3606: Upon receiving the request, the AMF in PLMN1 may suspend the registration timer and activate the registration suspension timer. The AMF may configure the expiration time of the registration suspension timer using the value provided by the UE (if provided). Alternatively, the AMF may use the value already configured by the operator of the core network. The AMF still maintains all existing contexts for the UE, including maintaining the UE's registration status, security context, and existing PDU sessions. However, with the registration suspension timer activated, the CN will not page the UE for downlink data until the UE deactivates the registration suspension timer. If the UE requests the CN to queue downlink data while the registration suspension timer is running and the CN is able to do so, then in step S3606a the CN may enable such functionality by having the AMF provide this indication to the SMF to update any existing PDU sessions for the UE. The SMF then notifies (one or more) UPFs to buffer any downlink data sent to the UE, not shown in the figure. If the policy control request trigger is met, the SMF notifies the PCF of the conditions met, as shown in step S3606b. The condition may be that the AF has subscribed to be notified when the UE's registration status is suspended. This notification may cause the AF to not send any data to the UE until the suspension is deactivated.

[0666] Step S3608: The AMF returns a Registration Accept message to the UE to indicate the status of the request. If the request is granted and if the AMF has changed the Registration Suspend Timer expiry value, the AMF shall include the new value in the Accept response. While the Registration Suspend Timer is running, the AMF may also provide an indication of whether the UE's request is granted to allow the CN to queue downlink data. The UE starts a timer which combines the value returned by the AMF or the value initially provided to track the remaining time the UE has before the CN will initiate the deregistration procedure. In other words, the UE needs to deactivate the Registration Suspend Timer maintained in the CN before the timer maintained by the UE expires so that the UE's registration state remains in RM-REGISTERED. While the Registration Suspend Timer is active, the UE's registration state is RM-REGISTERED and its connection state is CM-IDLE. However, the CN will not page the UE during this time.

[0667] Step S3610: The UE disconnects from PLMN1 and connects to PLMN2. After connecting to PLMN2, the UE may perform a mobility registration update or a periodic registration update to deactivate the registration suspension timer maintained by the AMF in PLMN2. In the request, the UE may include an indication to deactivate the registration suspension timer or set the expiration value to zero. The AMF in PLMN2 will then disable the registration suspension timer and re-enable the registration timer. The expiration time of the registration timer may be reset at this time instead of continuing from the previous value when it was suspended. If the UE has previously requested the CN to queue downlink data, the UE will receive that data when performing the service request. The UE may maintain connection with PLMN2 for the time required by the user in order to use services associated with SIM2. If the UE is in CM-IDLE state when the operation timer expires, the UE may decide to disconnect from PLMN2 and reconnect to PLMN1.

[0668] Step S3612: For the case where the UE decides to reconnect to PLMN1, the UE sends a mobility registration update or a periodic registration update request to PLMN1 to deactivate the registration suspension timer and reactivate the registration timer. The UE may provide an indication of the expiration of the registration suspension timer or a zero value to trigger the deactivation of the registration suspension timer.

[0669] Step S3614: The AMF in PLMN1 deactivates the registration suspension timer and re-enables the registration timer. At this time, the expiration time of the registration timer can be reset instead of continuing from the value when it was suspended in step S3606.

[0670] Step S3616: Similar to step S3608, the AMF in PLMN1 returns a registration accept response with a status of update request. If the request in step S3612 is a service request, the UE can start receiving queued downlink data. If not, the UE can perform a service request after this step to receive queued downlink data.

[0671] Step S3618: There may be situations where the UE is busy processing data associated with a PDU session or the UE remains connected to PLMN2 in the middle of a call. During these situations, the UE may stay at step S3610 for a time greater than the expiration time of the deregistration timer and the registration suspension timer. In these situations, the AMF in PLMN1 may deregister the UE for SIM1.

[0672] As part of the process of suspending the registration timer, the CN may also suspend paging the UE and buffer mobile terminated data for the UE. During this suspension period, the CN knows that the UE is not actively listening for paging requests, so the AMF may queue the paging request and instruct the SMF to guide the UPF to buffer mobile terminated data for the UE, such as Fig.36 As shown in step S3606a of . All security contexts established in the user plane for NAS signaling and PDU sessions are retained as if the UE was in CM-IDLE state. In fact, during the suspension, the CN and the UE maintain RM-REGISTERED and CM-IDLE states for the UE. This suspension state is similar to the RRC_INACTIVE state, but applies to the registration and connection management state of the UE. Therefore, after the UE switches back to using the SIM associated with the registration, the UE and the CN can quickly re-establish communication. When the UE requests activation of the registration suspension timer, this behavior can be triggered by including the paging criteria parameters as described above.

[0673] UE requests to stop paging

[0674] In some cases, the UE may be busy using services for one SIM and then receive a page for another SIM. The paging message may indicate what type of service caused the paging. Instead of having the network for the second SIM continue to page the UE, the UE may respond to the paging with a service request message to inform the network that the UE is busy and to stop paging the UE. The service request message may include, for example, an indication of what service the UE is currently performing on another system (e.g., emergency services), what services it is willing to respond to on this current system, what services it is unwilling to respond to on the current system, and a timer value indicating to the network when the network may page the UE again for the same type of service. Similarly, when the UE receives a NAS notification including an indication that the UE should respond to a paging and a paging cause, the UE may respond with a NAS notification response including an indication of what service the UE is currently performing on another system (e.g., emergency services), what services it is willing to respond to on this current system, what services it is unwilling to respond to on the current system, and a timer value indicating when the network may again attempt to page the UE for the same type of service or send a NAS notification to the UE. By the UE notifying the network, paging resources can be saved and the network may be able to signal to the data source that the UE is busy, e.g. a voice call goes directly to voicemail instead of trying to ring the UE. In the IoT use case, the information provided to the CN can be used to update the reachability status of the UE on an application server trying to reach the UE.

[0675] This feature may be useful in the case where the UE has dual Rx and single Tx capabilities. The UE may be in the middle of a call on SIM1 and receive a page for SIM2, such as Fig.37 As shown in . The UE can send a request to the network of SIM2 to inform the network to stop paging the UE. In this case, the UE may be actively receiving downlink data on one of the receivers and there may be a gap in the uplink transmission where the UE can send a request message to the network of SIM2. This feature may also be useful for cases where the UE has single Rx and single Tx capabilities and time division multiplexing between two SIMs on the same PLMN or between the PLMNs of two SIMs. Note that the UE can communicate with the same or different MNOs and the process will be the same.

[0676] Step S3702: Multi-SIM UE is registered to both PLMN1 and PLMN2. The UE may have dual Rx, single Tx capability or single Rx, single Tx capability with time multiplexing between the PLMNs of each SIM. In this case, the UE has dual Rx and single Tx capability.

[0677] Step S3704: The UE is currently receiving downlink data on Rx1 and monitoring paging on Rx2.

[0678] Step S3706: PLMN2 receives the data for SIM2 and pages the UE. The paging may include service prioritization information indicating what the paging is for.

[0679] Step S3708: The UE determines to notify PLMN2 that the UE is busy receiving data from PLMN1. The UE may check the service type found in the paging message using the user configured service prioritization list to make this determination. For example, the UE may be on an important voice call and the service type in the paging message indicates an incoming text message. The user may have configured the service prioritization list to indicate that text messages have a lower priority. Alternatively, the UE may have presented to the user in a GUI showing that an incoming text message for SIM2 is pending and the user has chosen to ignore the text message temporarily. When the UE receives data on Rx1, there may be time gaps when the UE does not transmit any UL data on a single Tx. During these gaps, the UE may be connected to PLMN2, so it can perform a request to notify the AMF in PLMN2 to stop paging the UE.

[0680] Step S3710: After successfully connecting to PLMN2, the UE may send a mobility registration update request to the AMF in PLMN2. This request may include an indication to activate the registration suspension timer, or it may include the expiration time of the registration suspension timer to indicate that the UE wishes the AMF to temporarily suspend paging the UE for a specified period of time. Alternatively, the indication may be provided in a service request message with the time at which the CN should stop paging the UE and the updated multi-SIM assistance information. When the registration suspension timer is active, the UE may also provide an indication to have the CN queue any downlink data for the UE. The UE will then be able to retrieve the queued downlink data after the UE reestablishes communication with the CN.

[0681] Step S3712: The AMF in PLMN2 returns the status of the request in an accept response. As part of the response, the CN may provide new values ​​for the expiry time of the registration suspension timer and whether the CN can queue any downlink data while the registration suspension timer is running. The response may include the status of the request and the time when the CN will stop paging the UE.

[0682] The above process shows that the UE is registered to two PLMNs (or MNOs), but it can also be applied to the scenario where both SIMs in the UE belong to the same MNO. The process will operate in a similar manner, except that when sending a mobility registration update request or service request to another PLMN, the UE will only send requests to a single PLMN.

[0683] When the UE sends a request to the PLMN to stop paging the UE, the UE may include multi-SIM assistance information in the request to inform the PLMN how long to stop paging the UE, what service type the UE is paged with, what service type the UE is not paged with, and whether data is buffered for the UE. This information may be grouped together as additional information provided by the UE to the PLMN to enable the PLMN to filter paging for the UE when the UE is busy. The multi-SIM assistance information may be organized as a policy provided by the UE to the PLMN or a collection of instructions sent to the PLMN in a service request or during a registration update request.

[0684] The core network provides notification of missed paging to the UE

[0685] Whenever the core network has paged the UE and the UE has not responded, the core network may track the number of times the UE has missed a page and notify the UE the next time the UE connects to the CN or via another access (e.g., a non-3GPP access). This functionality may be enabled if the UE has informed the CN during one of the registration procedures that it is a multi-SIM UE, or if the UE has enabled one of the parameters related to multi-SIM operation described herein (such as multi-SIM assistance information). The CN may notify the UE in response to a registration request or service request procedure. When the UE does not respond to a page, the CN may also provide the time and registration and / or tracking area at which the page was sent. As an alternative, if the UE supports connection to multiple access technologies (e.g., via a 3GPP access and via a non-3GPP access), the CN may send a notification to the UE via an access in which the UE may be in a CM-CONNECTED state. This information may allow the UE to identify paging conflicts and / or problems with paging handling and allow the UE to utilize one of the solutions mentioned above to help correct the problem. Note that the following procedure may apply to cases where the SIMs belong to the same MNO and to cases where the UE has dual Rx, single Tx or single Rx, single Tx capabilities. See Fig.38 .

[0686] Step S3802: Multi-SIM UE registers to both PLMN1 and PLMN2. In the case where the two SIMs belong to the same MNO, the UE will register the two SIMs to the same PLMN.

[0687] Step S3804: The UE is currently receiving downlink data from PLMN1.

[0688] Step S3806: PLMN2 receives the data for SIM2 and pages the UE. However, the UE does not receive the page or does not respond to the page due to receiving data from PLMN1, for example, the user is in an important voice call and does not want to be interrupted. The user may have received a prompt from the UE via the GUI, but decided to ignore the prompt. Note that the UE can operate with single Rx, single Tx or dual Rx, single Tx capabilities.

[0689] Step S3808: After a certain time, the UE connects to PLMN2.

[0690] Step S3810: The UE may perform any one of a registration procedure or a service request procedure to start receiving services from PLMN2.

[0691] Step S3812: In the acceptance response, the AMF in PLMN2 may provide the UE with information about any missed pages that it has saved. This information may include the time of the missed page, the tracking area and / or registration area to which the page was sent, and possible additional information about the page (such as, for example, the service category and other more detailed information (such as, for example, the phone number of the caller or text message sender, the PDU session ID and / or application ID, etc.)). Alternatively, when the UE is able to connect to multiple access networks (such as via 3GPP and non-3GPP accesses), the CN may send a notification to the UE via the access network in which the UE may be in the CM-CONNECTED state. Upon receiving this information, the UE can determine that (one or more) paging conflicts have occurred and identify steps that the UE can take to avoid such conflicts in the future. The UE may then perform one of the above-mentioned procedures to request a new temporary identifier for its PO that is separate from the current PO.

[0692] Another aspect of this solution is that the CN can wait for a configured number of missed pages before notifying the UE of the missed pages. The number of missed pages can be configured by operator policy, configured by commands from the operator's operations and management system, or even provided by the UE as Multi-SIM Assistance Information. When the UE indicates to the CN that the UE is a Multi-SIM device, the UE can provide in the Multi-SIM Assistance Information during one of the registration procedures a threshold number of missed pages that the CN uses to send information about missed pages to the UE. The CN will then start tracking the number of times the UE has not responded to pages, and when the threshold is reached, the CN will then notify the UE. In the notification, the CN can provide a list of all the times the UE missed receiving pages, including the timestamp, the tracking or registration area from which each page was sent, and the number of times the CN attempted to page the UE. The CN may also include additional information about what the page is for, such as service class and prioritization level, such as phone number, PDU session ID, application ID, etc.

[0693] Graphical User Interface

[0694] Fig.17 An example graphical user interface (GUI) that a UE may display to show a multi-SIM configuration of the UE is shown. The GUI may display a list of multi-SIM policies showing all PLMNs to which the UE is registered and provide a mechanism for the user to configure the priority associated with each registration. For each displayed SIM entry, an active state with a switch button is shown to allow the user to manually initiate the SIM switch process by pressing the button of the associated SIM entry. The GUI may also allow the user to access the information found in Table 2 for the corresponding PLMN by long pressing the associated entry. Fig.18 An example GUI showing information for individual SIM configuration associated with a PLMN registration. The user may also further configure certain parameters for a particular PLMN through this GUI.

[0695] Fig.33 Another example GUI for a multi-SIM UE is shown, where the UE supports three SIMs. The GUI lists the types of services enabled for each SIM. For SIM1, voice, SMS messaging, and data services are enabled, and may represent the primary SIM. SIM2 is enabled only for data services, while SIM3 is enabled for both voice and SMS messaging services. Both SIM2 and SIM3 may be secondary SIMs that may be used during travel.

[0696] In an exemplary embodiment of an electronic device, the electronic device is a UE, such as a smart phone. In an exemplary embodiment, the circuit system of the electronic device (e.g., UE) may include at least one or more processor devices (e.g., CPU). In an exemplary embodiment, the circuit system may also include one or more memories storing computer executable instructions. In an exemplary embodiment, the circuit system may include Figure 1F One or more of the components shown in .

[0697] In an exemplary embodiment, an electronic device (eg, UE) receives data from a core network.

[0698] The corresponding features of the present disclosure are defined by the following numbered paragraphs:

[0699] Paragraph 1. An electronic device comprising:

[0700] a receiver configured to receive a first subscriber identity module (SIM);

[0701] a receiver configured to receive a second SIM; and

[0702] The circuit system is configured as

[0703] receiving data from the first SIM;

[0704] A request is sent to a first public land mobile network (PLMN) to register the electronic device with the first PLMN, wherein the request indicates that the electronic device is a multi-SIM device and the request includes multi-SIM assistance information, and wherein the multi-SIM assistance information informs the first PLMN of the electronic device's preference for multi-SIM operation.

[0705] Paragraph 2. An electronic device as described in paragraph 1, wherein the multi-SIM assistance information includes one or more of: paging criteria, paging occasion separation, proposed temporary identifier, restricted paging area, and number of missed pages before notification.

[0706] Paragraph 3. An electronic device as described in paragraph 2, wherein the paging criteria includes at least one of service type category information or service prioritization level.

[0707] Paragraph 4. An electronic device as described in paragraph 3, wherein the service type category information includes one or more of the following: voice call, SMS message, other data, control plane signaling, emergency message, emergency call back, or mobile terminated exception data.

[0708] Paragraph 5. An electronic device as described in paragraph 4, wherein the other data includes Internet data, application data, or data associated with a protocol data unit (PDU) session.

[0709] Paragraph 6. An electronic device as described in Paragraph 3, wherein the service prioritization level includes a numerical level, a high or low level, a level associated with an emergency situation, or a single level.

[0710] Paragraph 7. An electronic device as described in paragraph 2, wherein paging occasion separation, proposed temporary identifiers, limiting paging areas, or number of missed pages before notification enhances a paging mechanism for a network for multi-SIM operation.

[0711] Paragraph 8. An electronic device as described in Paragraph 2, wherein a user of the device configures preferences regarding how the device operates for multi-SIM operation.

[0712] Paragraph 9. An electronic device as described in paragraph 1, wherein the request is sent via a control plane or a user plane.

[0713] Paragraph 10. An electronic device as described in paragraph 1, wherein the electronic device is a user equipment (UE).

[0714] Paragraph 11. An electronic device as described in paragraph 1, wherein the electronic device is configured to send a second request to a second PLMN, and the second request includes an identifier for a second SIM to be associated with the second PLMN, wherein the first PLMN forwards the second request to the second PLMN, and the second PLMN authenticates the credentials of the second SIM.

[0715] Paragraph 12. An electronic device as described in paragraph 11, wherein the electronic device includes in the second request a duration, a PDU session identifier, location information, an indication of buffering downlink data, and an indication that the electronic device is reachable via a user plane.

[0716] Paragraph 13. An electronic device as described in paragraph 11, wherein the circuit system is configured to receive a temporary ID from the second PLMN to be used for the paging request.

[0717] Paragraph 14. The electronic device of paragraph 13, wherein the circuit system is configured to update a registration status of the electronic device with respect to the second PLMN.

[0718] Paragraph 15. The electronic device as described in Paragraph 13, wherein the second PLMN also updates the registration status of the electronic device with respect to the second PLMN.

[0719] Paragraph 16. An electronic device as described in paragraph 11, wherein the identifier for the second SIM includes a SUPI, an IMSI, a GUTI, a 5G-S-TMSI, or a SUCI.

[0720] Paragraph 17. The electronic device as described in Paragraph 13, wherein when the electronic device is actively registered to the first PLMN, whenever there is a page for the second SIM, the temporary ID of the electronic device is used to page the electronic device.

[0721] Paragraph 18. An electronic device as described in paragraph 1, wherein the request is an initial registration request, a partial registration request, an indirect registration request, a registration update request, an initial attach request, a partial attach request, an indirect attach request, or a tracking area update (TAU) request.

[0722] Paragraph 19. A method performed by an electronic device, the method comprising:

[0723] receiving data from a first subscriber identity module (SIM); and

[0724] A request is sent to a first public land mobile network (PLMN) to register the electronic device with the first PLMN, wherein the request indicates that the electronic device is a multi-SIM device and the request includes multi-SIM assistance information, and wherein the multi-SIM assistance information informs the first PLMN of the electronic device's preference for multi-SIM operation.

[0725] Paragraph 20. A non-transitory computer readable medium comprising computer executable instructions that, when executed by an electronic device, cause the electronic device to:

[0726] receiving data from a first subscriber identity module (SIM); and

[0727] A request is sent to a first public land mobile network (PLMN) to register the electronic device with the first PLMN, wherein the request indicates that the electronic device is a multi-SIM device and the request includes multi-SIM assistance information, and wherein the multi-SIM assistance information informs the first PLMN of the electronic device's preference for multi-SIM operation.

[0728] Paragraph 21. An electronic device comprising:

[0729] a receiver configured to receive a first subscriber identity module (SIM);

[0730] a receiver configured to receive a second SIM;

[0731] circuitry configured to receive data from a first SIM,

[0732] wherein a first public land mobile network (PLMN) receives data associated with a temporary ID associated with the first SIM, and

[0733] wherein the first PLMN forwards a paging request or a NAS notification to the second PLMN, and the paging request or the NAS notification includes a temporary ID associated with the first SIM; and

[0734] The circuit system is configured to receive a paging request or a NAS notification from a second PLMN, wherein the paging request or the NAS notification is sent to the electronic device on the second PLMN.

[0735] Paragraph 22. The electronic device as described in Paragraph 21, wherein the electronic device is registered with the first PLMN and the second PLMN at the same time.

[0736] Paragraph 23. The electronic device of Paragraph 21, wherein the electronic device has an inactive registration with the first PLMN.

[0737] Paragraph 24. The electronic device of Paragraph 21, wherein the electronic device has an active registration with a second PLMN.

[0738] Paragraph 25. A method performed by an electronic device, the method comprising:

[0739] receiving data from a first subscriber identity module (SIM),

[0740] wherein a first public land mobile network (PLMN) receives data associated with a temporary ID associated with the first SIM, and

[0741] wherein the first PLMN forwards a paging request or a NAS notification to the second PLMN, and the paging request or the NAS notification includes a temporary ID associated with the first SIM; and

[0742] A paging request or NAS notification is received from the second PLMN, wherein the paging request or NAS notification is sent to the electronic device on the second PLMN.

[0743] Paragraph 26. A non-transitory computer-readable medium comprising computer-executable instructions that, when executed by an electronic device, cause the electronic device to:

[0744] receiving data from a first subscriber identity module (SIM),

[0745] wherein a first public land mobile network (PLMN) receives data associated with a temporary ID associated with the first SIM, and

[0746] wherein the first PLMN forwards a paging request or a NAS notification to the second PLMN, and the paging request or the NAS notification includes a temporary ID associated with the first SIM; and

[0747] A paging request or NAS notification is received from the second PLMN, wherein the pagi...

Claims

1. An electronic device, comprising: a receiver configured to receive a first subscriber identity module (SIM); a receiver configured to receive a second SIM; as well as A circuit system is configured to: receiving data from the first SIM; as well as A request is sent to a first public land mobile network (PLMN) to register the electronic device with the first PLMN, wherein the request indicates that the electronic device is a multi-SIM device and the request includes multi-SIM assistance information, and wherein the multi-SIM assistance information informs the first PLMN of the electronic device's preference for multi-SIM operation.

2. The electronic device of claim 1, wherein the multi-SIM assistance information comprises one or more of: paging criteria, paging occasion separation, a proposed temporary identifier, a restricted paging area, and a number of missed pages before notification.

3. The electronic device of claim 2, wherein the paging criteria comprises at least one of service type category information or a service prioritization level.

4. The electronic device of claim 3, wherein the service type category information comprises one or more of: voice call, SMS message, other data, control plane signaling, emergency message, emergency call back, or mobile terminated exception data. 5 . The electronic device of claim 4 , wherein the other data comprises Internet data, application data, or data associated with a protocol data unit (PDU) session.

6. The electronic device of claim 3, wherein the service prioritization level comprises a numerical level, a high or low level, a level associated with an emergency situation, or a single level.

7. The electronic device of claim 2, wherein paging occasion separation, proposed temporary identifiers, restricted paging areas, or number of missed pages before notification enhances the network's paging mechanism for multi-SIM operation.

8. The electronic device of claim 2, wherein a user of the device configures preferences regarding how the device operates for multi-SIM operation.

9. The electronic device of claim 1, wherein the request is sent via a control plane or a user plane.

10. The electronic device of claim 1, wherein the electronic device is a user equipment (UE).

11. The electronic device of claim 1 , wherein the electronic device is configured to send a second request to a second PLMN, and the second request includes an identifier for a second SIM to be associated with the second PLMN, wherein the first PLMN forwards the second request to the second PLMN, and the second PLMN authenticates the credentials of the second SIM.

12. The electronic device of claim 11, wherein the electronic device includes in the second request a duration, a PDU session identifier, location information, an indication of buffering downlink data, and an indication that the electronic device is reachable via a user plane.

13. The electronic device of claim 11, wherein the circuit system is configured to receive a temporary ID from the second PLMN to be used for the paging request.

14. The electronic device of claim 13, wherein the circuit system is configured to update a registration status of the electronic device with respect to a second PLMN.

15. The electronic device of claim 13, wherein the second PLMN further updates a registration status of the electronic device with respect to the second PLMN.

16. The electronic device of claim 11, wherein the identifier for the second SIM comprises a SUPI, an IMSI, a GUTI, a 5G-S-TMSI, or a SUCI.

17. The electronic device according to claim 13, wherein: When the electronic device is actively registered to the first PLMN, whenever there is a paging for the second SIM, the temporary ID of the electronic device is used to page the electronic device.

18. The electronic device of claim 1, wherein the request is an initial registration request, a partial registration request, an indirect registration request, a registration update request, an initial attach request, a partial attach request, an indirect attach request, or a Tracking Area Update (TAU) request.

19. A method performed by an electronic device, the method comprising: receiving data from a first subscriber identity module (SIM); as well as A request is sent to a first public land mobile network (PLMN) to register the electronic device with the first PLMN, wherein the request indicates that the electronic device is a multi-SIM device and the request includes multi-SIM assistance information, and wherein the multi-SIM assistance information informs the first PLMN of the electronic device's preference for multi-SIM operation.

20. A non-transitory computer-readable medium comprising computer-executable instructions that, when executed by an electronic device, cause the electronic device to: receiving data from a first subscriber identity module (SIM); and A request is sent to a first public land mobile network (PLMN) to register the electronic device with the first PLMN, wherein the request indicates that the electronic device is a multi-SIM device and the request includes multi-SIM assistance information, and wherein the multi-SIM assistance information informs the first PLMN of the electronic device's preference for multi-SIM operation.

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