Connection Pause for Multiple SIMs

Abstract

Apparatus, method, and system for connection suspension of a SIM are disclosed. An apparatus 600 includes a processor 605, a first SIM 645 registered with a first mobile communication network, a second SIM 650 registered with a second mobile communication network, and a transceiver 625 communicating with the first and second mobile communication networks. The processor 605 receives 815 a communication trigger associated with the first SIM 645, the communication trigger indicating a service type, and determines 820 whether to apply a short connection suspension or a long connection suspension to the second SIM 650, the determination being based on the service type. The processor 605 additionally applies 825 one of the short connection suspension and the long connection suspension selected to the second SIM 650.

Description

Technical Field

[0001] The subject matter disclosed herein generally relates to wireless communication, and more particularly, to suspending the connection of one SIM during multi-SIM operation. Background Art

[0002] The following abbreviations and acronyms are defined herein, at least some of which are referred to in the following description.

[0003] 3rd Generation Partnership Project (“3GPP”), 5th Generation Core (“5GC”), 5th Generation QoS Indicator (“5QI”), Access and Mobility Management Function (“AMF”), Access Network Performance (“ANP”), Access Point Name (“APN”), Access Stratum (“AS”), Access Service Steering, Switching and Splitting (“ATSSS”), Allocation / Retention Policy (“ARP”), Application Programming Interface (“API”), Common Search Space (“CSS”), Data Network Name (“DNN”), Data Radio Bearer (“DRB”), Differentiated Services Code Point (“DSCP”), Downlink (“DL”), Enhanced Mobile Broadband (“eMBB”), Encapsulating Security Payload (“ESP”), Evolved Node B (“eNB”), Evolved Packet Core (“EPC”), Evolved UMTS Terrestrial Radio Access Network (“E-UTRAN”), European Telecommunications Standards Institute (“ETSI”), Echo Acknowledgement Indicator (“EAI”), Echo Request Indicator (“ERI”), ERI-d refers to the ERI associated with the virtual payload, and ERI-v refers to the ERI associated with the valid payload), Globally Unique Temporary UE Identity (“GUTI”), General Packet Radio Service (“GPRS”), GPRS Tunneling Protocol (“GTP”, GTP-C refers to the control signaling tunnel, and GTP-U refers to the user data tunnel), Home Subscriber Server (“HSS”), Internet of Things (“IoT”), IP Multimedia Subsystem (“IMS”,Also known as “IP Multimedia Core Network Subsystem”), Internet Protocol (“IP”), Key Performance Indicator (“KPI”), Licensed-Assisted Access (“LAA”), Load-Based Equipment (“LBE”), Listen-Before-Talk (“LBT”), Long-Term Evolution (“LTE”), LTE-Advanced (“LTE-A”), Media Access Control (“MAC”), Multiple Access (“MA”), Modulation and Coding Scheme (“MCS”), Machine-Type Communication (“MTC”), Massive MTC (“mMTC”), Mobile Network Operator (“MNO”), Mobility Management (“MM”), Mobility Management Entity (“MME”), Multiple-Input Multiple-Output (“MIMO”), Multipath TCP (“MPTCP”), Multi-User Shared Access (“MUSA”), Non-Access Stratum (“NAS”), Narrowband (“NB”), Network Function (“NF”), Network Access Identifier (“NAI”), Next Generation (e.g., 5G) Node B (“gNB”), Next Generation Radio Access Network (“NG-RAN”), New Radio (“NR”), Policy Control and Charging (“PCC”), Policy Control Function (“PCF”), Policy Control and Charging Rules Function (“PCRF”), Packet Data Network (“PDN”), Packet Data Unit (“PDU”), PDN Gateway (“PGW”), Public Land Mobile Network (“PLMN”), Quality of Service (“QoS”), QoS Class Identifier (“QCI”), Registration Area (“RA”), Radio Access Network (“RAN”), Radio Access Technology (“RAT”), Radio Resource Control (“RRC”), Receive (“RX”), Single Network Slice Selection Assistance Information (“S-NSSAI”), Scheduling Request (“SR”), Secure User Plane Location (“SUPL”), Serving Gateway (“SGW”), Session Management Function (“SMF”), Stream Control Transmission Protocol (“SCTP”), System Information Block (“SIB”), Tracking Area (“TA”), Transmission Control Protocol (“TCP”), Transmission (“TX”), Unified Data Management (“UDM”), User Entity / Device (Mobile Terminal) (“UE”), Uplink (“UL”), User Plane (“UP”), Universal Mobile Telecommunications System (“UMTS”), Ultra-Reliable and Low-Latency Communication (“URLLC”), User Datagram Protocol (“UDP”), UE Routing Selection Policy (“URSP”), Unstructured Supplementary Service Data (USSD), Wireless Local Area Network (“WLAN”) and Worldwide Interoperability for Microwave Access (“WiMAX”).

[0004] Some UEs support multiple subscriber identity modules, such as USIM-1 and USIM-2, for the same MNO or different MNOs. The following operating modes of multi / dual USIM devices are defined in the GSMA TS.37 document: passive, dual SIM / dual standby, and dual SIM / dual active.

[0005] In the passive mode, the UE contains two SIMs, but only one can be selected for use at any given time. A passive dual SIM device is effectively a single SIM device because the SIMs share a single transceiver, and the UE can only be logically connected to a single network at any given time. In other words, only a single USIM module / profile is registered at a given time.

[0006] In the dual SIM dual standby (DSDS) mode, both SIMs can be used for idle mode network connections, but when a radio connection is activated, the second connection is disabled. As in the passive case, the SIMs in a DSDS device share a single transceiver. Through time division multiplexing, the two radio connections are maintained in the idle mode. When a call is made on one SIM to a network, it is no longer possible to maintain a radio connection to the network of the second SIM, so that connection is unavailable during the call. Registration with the second network is maintained. The UE maintains idle operation on one subscription while maintaining a best effort data connection on the other subscription.

[0007] Dual SIM dual active (DSDA): Both SIMs can be used in both the idle and connected modes. Each SIM has a dedicated transceiver, which means that at the modem level, there is no mutual dependency for idle or connected mode operation. Note that in some DSDA devices, the second transceiver may only be 2G. SUMMARY OF THE INVENTION

[0008] Methods for pausing the connection of one SIM during multi-SIM operation are disclosed. Apparatuses and systems also perform the functions of these methods.

[0009] A method for a UE to pause the connection of one SIM during multi-SIM operation includes registering a first SIM with a first mobile communication network and registering a second SIM with a second mobile communication network. The first method includes receiving a communication trigger associated with the first SIM, the communication trigger indicating a service type, and determining whether to apply a short connection pause or a long connection pause to the second SIM. Here, the determination is based on the service type. The first method includes applying one of a short connection pause and a long connection pause to the second SIM.

[0010] A method for a network function (e.g., eNB or gNB) to suspend the connection of one SIM during multi-SIM operation includes receiving an RRC layer suspension request from a UE. The method includes maintaining the UE AS context of the UE. The method includes disabling downlink transmission to the UE in response to the RRC layer suspension request. The method includes enabling downlink transmission to the UE in response to receiving an RRC layer connection resume request from the UE. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] A more specific description of the embodiments briefly described above will be presented by reference to specific embodiments shown in the accompanying drawings. It should be understood that these drawings depict only some embodiments and should not be considered as limiting the scope. These embodiments will be described and explained with additional specificity and detail by using the drawings, wherein:

[0012] Figure 1 is a schematic block diagram showing an embodiment of a wireless communication system for suspending the connection of one SIM during multi-SIM operation;

[0013] Figure 2A is a block diagram showing an embodiment of a single USIM UE and a multi-USIM UE;

[0014] Figure 2B is a block diagram showing an embodiment of the protocol stack of a multi-USIM UE;

[0015] Figure 3 is a flowchart showing an embodiment of the process for suspending the connection of one SIM during multi-SIM operation;

[0016] Figure 4A is a signal flow diagram showing an embodiment of suspending the connection of one SIM during multi-SIM operation;

[0017] Figure 4B is Figure 4A a continuation of the process depicted in;

[0018] Figure 5A is a signal flow diagram showing an embodiment of resuming the connection of one SIM during multi-SIM operation;

[0019] Figure 5B is Figure 5A a continuation of the process depicted in;

[0020] Figure 6 is a block diagram showing an embodiment of a UE device apparatus for suspending the connection of one SIM during multi-SIM operation;

[0021] Figure 7is a block diagram showing an embodiment of a network device apparatus for pausing the connection of one SIM during multi-SIM operation;

[0022] Figure 8 is a flowchart showing an embodiment of a first method for pausing the connection of one SIM during multi-SIM operation; and

[0023] Figure 9 is a flowchart showing an embodiment of a second method for pausing the connection of one SIM during multi-SIM operation. DETAILED DESCRIPTION

[0024] As will be understood by those skilled in the art, aspects of the embodiments may be embodied as a system, apparatus, method, or program product. Accordingly, the embodiments may take the form of an entirely hardware embodiment, an entirely software embodiment (including firmware, resident software, microcode, etc.), or an embodiment combining software and hardware aspects.

[0025] For example, the disclosed embodiments may be embodied as hardware circuits, including custom very large scale integration ("VLSI") circuits or gate arrays, off-the-shelf semiconductors, such as logic chips, transistors, or other discrete components. The disclosed embodiments may also be embodied in programmable hardware devices, such as field programmable gate arrays, programmable array logic, programmable logic devices, etc. As another example, the disclosed embodiments may include one or more physical or logical blocks of executable code, which may be organized, for example, as objects, procedures, or functions.

[0026] In addition, the embodiments may take the form of a program product embodied in one or more computer-readable storage devices storing machine-readable code, computer-readable code, and / or program code - hereinafter referred to as code. The storage device may be tangible, non-transitory, and / or non-transmissive. The storage device may not embody a signal. In a particular embodiment, the storage device only uses a signal to access the code.

[0027] Any combination of one or more computer-readable media may be utilized. The computer-readable media may be a computer-readable storage medium. The computer-readable storage medium may be a storage device storing the code. The storage device may be, for example but not limited to, an electronic, magnetic, optical, electromagnetic, infrared, holographic, micro-mechanical, or semiconductor system, apparatus, or device, or any suitable combination of the foregoing.

[0028] More specific examples (non-exhaustive list) of storage devices would include the following: electrical connections with one or more wires, portable computer disks, hard disks, random access memory ("RAM"), read-only memory ("ROM"), erasable programmable read-only memory ("EPROM" or flash memory), portable compact disc read-only memory ("CD-ROM"), optical storage devices, magnetic storage devices, or any suitable combination of the foregoing. In the context of this document, a computer-readable storage medium can be any tangible medium that is capable of containing, or storing a program for use by or in connection with an instruction execution system, apparatus, or device.

[0029] References throughout this specification to "one embodiment", "an embodiment", or similar language mean that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment. Thus, unless otherwise expressly stated, the appearances of the phrases "in one embodiment", "in an embodiment", and similar language throughout this specification may, but do not necessarily, all refer to the same embodiment, but rather mean "one or more but not all embodiments". Unless otherwise expressly stated, the terms "comprises", "comprising", "has", and variations thereof mean "including but not limited to". Unless otherwise expressly stated, a list of items does not imply that any or all of the items are mutually exclusive. Unless otherwise expressly stated, the terms "a", "an", and "the" also mean "one or more".

[0030] As used herein, a list with the conjunction "and / or" includes any single item in the list or a combination of items in the list. For example, the list of A, B, and / or C includes only A, only B, only C, the combination of A and B, the combination of B and C, the combination of A and C, or the combination of A, B, and C. As used herein, a list using the term "one or more" includes any single item in the list or a combination of items in the list. For example, one or more of A, B, and C includes only A, only B, only C, the combination of A and B, the combination of B and C, the combination of A and C, or the combination of A, B, and C. For example, "one of A, B, and C" includes only A, only B, or only C and excludes the combination of A, B, and C. As used herein, "a member selected from the group consisting of A, B, and C" includes one and only one of A, B, or C and excludes the combination of A, B, and C. As used herein, "a member selected from the group consisting of A, B, and C and combinations thereof" includes only A, only B, only C, the combination of A and B, the combination of B and C, the combination of A and C, or the combination of A, B, and C.

[0031] In addition, the features, structures, or characteristics of the described embodiments may be combined in any suitable manner. In the following description, numerous specific details are provided, such as examples of programming, software modules, user selections, network transactions, database queries, database structures, hardware modules, hardware circuits, hardware chips, etc., to provide a thorough understanding of the embodiments. However, those skilled in the relevant art will recognize that the embodiments may be practiced without one or more of the specific details, or with other methods, components, materials, etc. In other instances, well-known structures, materials, or operations are not shown or described in detail to avoid obscuring aspects of the embodiments.

[0032] Aspects of the embodiments are described below with reference to the schematic flowcharts and / or schematic block diagrams of methods, apparatuses, systems, and program products according to the embodiments. It should be understood that each block of the schematic flowcharts and / or schematic block diagrams, and combinations of blocks in the schematic flowcharts and / or schematic block diagrams, can be implemented by code. This code can be provided to a processor of a general-purpose computer, a special-purpose computer, or other programmable data processing device to produce a machine, such that the instructions executed via the processor of the computer or other programmable data processing device create a device for implementing the functions / actions specified in the schematic flowchart and / or schematic block diagram.

[0033] The code can also be stored in a storage device, which can direct a computer, other programmable data processing device, or other device to operate in a specific manner, such that the instructions stored in the storage device produce an article of manufacture including instructions for implementing the functions / actions specified in the schematic flowchart and / or schematic block diagram.

[0034] The code can also be loaded onto a computer, other programmable data processing device, or other device so that a series of operational steps are performed on the computer, other programmable device, or other device, thereby producing a computer-implemented process, such that the code executed on the computer or other programmable device provides a process for implementing the functions / actions specified in the schematic flowchart and / or schematic block diagram.

[0035] The schematic flowcharts and / or schematic block diagrams in the drawings illustrate the architecture, functions, and operations of possible implementations of apparatuses, systems, methods, and program products according to various embodiments. In this regard, each block in the schematic flowcharts and / or schematic block diagrams may represent a module, segment, or portion of code that includes one or more executable instructions for implementing the specified logical function.

[0036] It should also be noted that, in some alternative implementations, the functions recited in the boxes may occur out of the order recited in the figures. For example, depending on the functions involved, two consecutively shown boxes may actually be executed substantially simultaneously, or these boxes may sometimes be executed in the reverse order. Other steps and methods may be conceived that are equivalent in function, logic, or effect to one or more boxes or portions thereof of the illustrated figures.

[0037] The description of an element in each figure may refer to an element in a previous figure. In all of the figures, the same numerals represent the same elements, including alternative embodiments of the same element.

[0038] Methods, apparatuses, and systems for pausing the connection of one SIM during multi-SIM operation are disclosed. In various embodiments, the present disclosure introduces enhancements to the DSDS operation mode of a multi-SIM UE, in which the UE can dynamically decide which connection to use, e.g., the connection of USIM-A or the connection of USIM-B, regardless of whether there is any existing connection to any USIM. Note that an "existing connection" refers to, for example, an existing NAS connection in which the UE is in the CM connection state of a USIM.

[0039] Mechanisms are disclosed herein that allow for pausing (e.g., interrupting) and resuming an ongoing connection in a network associated with USIM-A, such that the UE can temporarily move away to reach a network associated with USIM-B and then return to the network associated with USIM-A in a network-controlled manner. Various embodiments describe optimizations for temporarily pausing the connection of one USIM (e.g., USIM-A) in an efficient manner by reducing control plane signaling for pausing and resuming. Various embodiments describe the network behavior when an ongoing connection in a network associated with USIM-A is paused, e.g., determining whether PLMN-A of USIM-A (e.g., SMF / UPF) should buffer or store DL packets, how to handle GBR QoS flows, and what procedures the UE uses to resume the paused connection of USIM-A and what information is exchanged between the UE and the network during connection resume.

[0040] Figure 1FIG. 0 depicts a wireless communication system 100 for pausing the connection of one SIM during multi-SIM operation in accordance with an embodiment of the present disclosure. In one embodiment, the wireless communication system 100 includes at least one remote unit 105, a 5G-RAN 115, and a mobile core network 140. The 5G-RAN 115 and the mobile core network form a mobile communication network. The 5G-RAN 115 may be composed of a 3GPP access network 120 including at least one cellular base station unit 121 and / or a non-3GPP access network 130 including at least one access point 131. The remote unit communicates with the 3GPP access network 120 using a 3GPP communication link 123 and communicates with the non-3GPP access network 130 using a non-3GPP communication link 133. Although Figure 1 a specific number of remote units 105, 3GPP access networks 120, cellular base station units 121, 3GPP communication links 123, non-3GPP access networks 130, access points 131, non-3GPP communication links 133, and mobile core networks 140 are depicted in FIG. 0, those skilled in the art will recognize that any number of remote units 105, 3GPP access networks 120, cellular base station units 121, 3GPP communication links 123, non-3GPP access networks 130, access points 131, non-3GPP communication links, and mobile core networks 140 may be included in the wireless communication system 100.

[0041] In one implementation, the wireless communication system 100 complies with the 5G system specified in the 3GPP specifications. However, more generally, the wireless communication system 100 may implement some other open or proprietary communication networks, such as LTE / EPC (referred to as 4G) or WiMAX, as well as other networks. The present disclosure is not intended to be limited to the implementation of any specific wireless communication system architecture or protocol.

[0042] In one embodiment, the remote unit 105 may include a computing device, such as a desktop computer, a laptop computer, a personal digital assistant (“PDA”), a tablet computer, a smart phone, a smart TV (e.g., a TV connected to the Internet), a smart appliance (e.g., an appliance connected to the Internet), a set-top box, a game console, a security system (including security cameras), an in-vehicle computer, a network device (e.g., a router, a switch, a modem), etc. In some embodiments, the remote unit 105 includes a wearable device, such as a smart watch, a fitness band, an optical head-mounted display, etc. Additionally, the remote unit 105 may be referred to as a UE, a subscriber unit, a mobile device, a mobile station, a user, a terminal, a mobile terminal, a fixed terminal, a subscriber station, a user terminal, a wireless transmit / receive unit (“WTRU”), a device, or other terms used in the art.

[0043] The remote unit 105 can communicate directly with one or more cellular base station units 121 in the 3GPP access network 120 via uplink (“UL”) and downlink (“DL”) communication signals. Additionally, the UL and DL communication signals can be carried on the 3GPP communication link 123. Similarly, the remote unit 105 can communicate with one or more access points 131 in the non-3GPP access network 130 via UL and DL communication signals carried on the non-3GPP communication link 133. Here, the access networks 120 and 130 are intermediate networks that provide the remote unit 105 with access to the mobile core network 140.

[0044] In some embodiments, the remote unit 105 communicates with an application server 151 (or other communication peer) via a network connection to the mobile core network 140. For example, an application in the remote unit 105 (e.g., a web browser, a media client, a phone / VoIP application) can trigger the remote unit 105 to establish a PDU session (or other data connection) with the mobile core network 140 using the 5G-RAN 115 (e.g., the 3GPP access network 120 and / or the non-3GPP access network 130). Then, the mobile core network 140 relays traffic between the remote unit 105 and the data network 150 (e.g., the application server 151) using the PDU session. Note that the remote unit 105 can establish one or more PDU sessions (or other data connections) with the mobile core network 140. In this way, the remote unit 105 can have at least one PDU session for communicating with the data network 150. The remote unit 105 can establish additional PDU sessions for communicating with other data networks and / or other communication peers.

[0045] The cellular base station units 121 can be distributed over a geographical area. In certain embodiments, the cellular base station units 121 can also be referred to as access terminals, bases, base stations, Node Bs, eNBs, gNBs, home Node Bs, relay nodes, devices, or any other term used in the art. The cellular base station units 121 are generally part of a radio access network (“RAN”), such as the 3GPP access network 120, which can include one or more controllers communicatively coupled to one or more corresponding cellular base station units 121. These and other elements of the radio access network are not shown, but are generally well known to those of ordinary skill in the art. The cellular base station units 121 are connected to the mobile core network 140 via the 3GPP access network 120.

[0046] The cellular base station unit 121 can serve multiple remote units 105 within a service area, such as a cell or a cell sector, via a 3GPP communication link 123. The cellular base station unit 121 can communicate directly with one or more remote units 105 via communication signals. Typically, the cellular base station unit 121 transmits DL communication signals to serve the remote units 105 in the time, frequency, and / or spatial domains. Additionally, the DL communication signals can be carried on the 3GPP communication link 123. The 3GPP communication link 123 can be any suitable carrier in the licensed or unlicensed radio spectrum. The 3GPP communication link 123 facilitates communication between one or more remote units 105 and / or one or more cellular base station units 121.

[0047] The non-3GPP access network 130 can be distributed over a geographical area. Each non-3GPP access network 130 can serve multiple remote units 105 having a service area. Typically, the service area of the non-3GPP access network 130 is smaller than the service area of the cellular base station unit 121. An access point 131 in the non-3GPP access network 130 can communicate directly with one or more remote units 105 by receiving UL communication signals and transmitting DL communication signals to serve the remote units 105 in the time, frequency, and / or spatial domains. Both the DL and UL communication signals are carried on the non-3GPP communication link 133. The 3GPP communication link 123 and the non-3GPP communication link 133 can employ different frequencies and / or different communication protocols. In various embodiments, the access point 131 can communicate using the unlicensed radio spectrum. The mobile core network 140 can provide services to the remote units 105 via the non-3GPP access network 130, as described in more detail herein.

[0048] In some embodiments, the non-3GPP access network 130 is connected to the mobile core network 140 via an interworking function 135. The interworking function 135 provides interworking between the remote units 105 and the mobile core network 140. In some embodiments, the interworking function 135 is a non-3GPP interworking function (“N3IWF”), and in other embodiments, it is a trusted non-3GPP gateway function (“TNGF”). The N3IWF supports connecting an “untrusted” non-3GPP access network to the mobile core network (e.g., 5GC), while the TNGF supports connecting a “trusted” non-3GPP access network to the mobile core network. The interworking function 135 supports connections to the mobile core network 140 via “N2” and “N3” interfaces, and it relays “N1” signaling between the remote units 105 and the AMF 143. As shown, both the 3GPP access network 120 and the interworking function 135 use the “N2” interface to communicate with the AMF 143. The interworking function 135 also uses the “N3” interface to communicate with the UPF 141.

[0049] In some embodiments, the non-3GPP access network 130 can be controlled by the MNO of the mobile core network 140 and can directly access the mobile core network 140. This non-3GPP AN deployment is referred to as a "trusted non-3GPP access network". When the non-3GPP access network 130 is operated by an MNO or a trusted partner, it is considered "trusted" and supports certain security features, such as strong air interface encryption. In contrast, a non-3GPP AN deployment that is not controlled by the operator (or trusted partner) of the mobile core network 140, cannot directly access the mobile core network 140, or does not support certain security features is referred to as an "untrusted" non-3GPP access network.

[0050] In one embodiment, the mobile core network 140 is a 5G Core ("5GC") or an Evolved Packet Core ("EPC"), which can be coupled to a data network (e.g., data network 150, such as the Internet and private data networks, and other data networks). The remote unit 105 can have a subscription or other account with the mobile core network 140. Each mobile core network 140 belongs to a Public Land Mobile Network ("PLMN"). The present disclosure is not intended to be limited to the implementation of any particular wireless communication system architecture or protocol.

[0051] The mobile core network 140 includes several Network Functions ("NFs"). As shown, the mobile core network 140 includes multiple User Plane Functions ("UPFs"). Here, the mobile core network 140 includes at least the UPF 141 that serves the 3GPP access network 120 and the non-3GPP access network 130. Note that in some embodiments, the mobile core network can include one or more intermediate UPFs, such as a first intermediate UPF that serves the non-3GPP access network 130 and a second intermediate UPF that serves the 3GPP access network 120. In such an embodiment, the UPF 141 will be the anchor UPF that receives the UPF services of the two intermediate UPFs.

[0052] The mobile core network 140 also includes multiple Control Plane Functions, including but not limited to the Access and Mobility Management Function ("AMF") 143, the Session Management Function ("SMF") 145, the Policy Control Function ("PCF") 147, and the Unified Data Management Function ("UDM") 149 that serve the 3GPP access network 120 and the non-3GPP access network 130. In some embodiments, the mobile core network 140 can also include an Authentication Server Function ("AUSF"), a Network Repository Function ("NRF") (used by various NFs to discover and communicate with each other via APIs), or other NFs defined for the 5GC.

[0053] In various embodiments, the mobile core network 140 supports different types of mobile data connections and different types of network slices, where each mobile data connection utilizes a specific network slice. Each network slice includes a set of CP and UP network functions, where each network slice is optimized for a specific type of service or traffic class. For ease of illustration, different network slices are not shown in Figure 1 , but their support is assumed. In one example, each network slice includes an SMF and a UPF, but various network slices share the AMF 143, PCF 147, and UDM 149. In another example, each network slice includes an AMF, an SMF, and a UPF.

[0054] Although Figure 1 a specific number and type of network functions are depicted, those skilled in the art will recognize that any number and type of network functions may be included in the mobile core network 140. Additionally, in the case where the mobile core network 140 is an EPC, the depicted network functions may be replaced with appropriate EPC entities, such as an MME, an S-GW, a P-GW, an HSS, etc.

[0055] As depicted, the remote unit 105 includes a USIM-A 107 and a USIM-B 109. For ease of illustration, the USIM-A 107 and the USIM-B 109 are depicted as being associated with the same PLMN. Additionally, the USIM-A 107 and the USIM-B 109 may be associated with the same or different network slices of the same PLMN. In such a case, the PLMN may interpret the remote unit 105 as two different remote units, each with its own network registration. In other embodiments, the USIM-A 107 and the USIM-B 109 may be associated with different PLMNs.

[0056] In certain embodiments, the remote unit 105 receives a communication trigger associated with a first SIM, the communication trigger indicating a service type, and determines whether to apply a short connection suspension or a long connection suspension to a second SIM if there is a NAS connection to the second SIM, the determination being based on the service type. The remote unit 105 additionally applies one of the short connection suspension and the long connection suspension selected for the second SIM.

[0057] In various embodiments, the remote unit 105 is capable of indicating the following capabilities to the network during the registration process (e.g., in a registration request message to the AMF 143): 1) enhanced multi-USIM support, 2) whether multiple suspended states (e.g., short suspension and long suspension) are supported. Based on the supported (or preferred) multi-USIM operation mode from the network (e.g., indicated in the registration acceptance message from the AMF 143), the remote unit 105 internally configures whether to apply a) no multi-USIM enhancement, b) support for a single (e.g., long suspension state), or c) multiple suspended states.

[0058] In some embodiments, the remote unit 105 is capable of determining whether to apply a short connection suspension or a long connection suspension (e.g., based on an indication of the service type in a paging message, or the MO service type, or other indications regarding upcoming communications). In the case of a short suspension state, the remote unit 105 indicates (e.g., in an RRC message) to the source USIM RAN node to enter the short suspension state.

[0059] In certain embodiments, the remote unit 105 maintains a timer for the short suspension state. One or more of the following mechanisms for configuring the timer can be applied: the remote unit 105 can receive the timer configuration from the RAN node via a unicast message (e.g., suspension acceptance as part of the RRC signaling procedure for suspension), or the timer configuration can be broadcast in the SIB, or the timer configuration can be negotiated during a NAS procedure (e.g., registration procedure or UE configuration update). Note that the SIB can advertise multi-USIM support (i.e., the feature is supported in the network), multi-USIM preference, timer values, etc. In certain embodiments, the value of the timer can affect the decision of the remote unit 105 to enter a short suspension state or a long suspension state.

[0060] In some embodiments, if multi-USIM operation enhancement is preferred and configured in the remote unit 105, the remote unit 105 is capable of changing the radio capabilities it advertises to the network. For example, the remote unit 105 can change the radio interface capabilities to not support dual connectivity or certain carrier aggregation modes in order to allow the remote unit 105 to camp (e.g., in the idle state) in a different cell (e.g., macro cell) of another USIM. If the remote unit 105 registers with the network of the first USIM and dual radio capabilities are signaled to the network, and the remote unit 105 registers with the network of the second USIM while multi-USIM operation enhancement is configured, the remote unit 105 can initiate a signaling procedure for changing (e.g., reducing) its radio capabilities in the network serving the first USIM.

[0061] In various embodiments, the 5G-RAN 115 implements the following with reference to Figure 3 and Figures 4A to 4BApparatus for a short pause state is described in detail. The short pause state may share features with the traditional RRC inactive state, but differs in that the remote unit 105 is marked as unreachable (i.e., RAN paging for downlink data or signaling is not performed, even if there are ongoing UL / DL data or signaling transmissions (even buffered at, for example, the PDCP layer) and / or no RAN notification area is allocated to the UE, the RRC connection is suspended).

[0062] In various embodiments, the AMF 143 (or MME) is capable of receiving multi-USIM capability information of the remote unit 105. The AMF 143 (or MME) indicates the supported (or preferred) operation mode, e.g., does not support multi-USIM capability, only supports the long pause state, supports both the short pause and long pause states.

[0063] In various embodiments, the remote unit 105 may initiate application / service level signaling before performing the connection suspension procedure to notify the application server 151 (or other communication peer) that the device is temporarily unavailable, so that the service or communication exchange can be interrupted (or paused or terminated) in a controlled manner at the application / service layer. When the suspended USIM resumes / continues, the remote unit 105 may notify the application server 151 (or communication peer) of its availability for communication.

[0064] Additional details of pausing and resuming the connection of one SIM during multi-SIM operation are discussed below.

[0065] Figure 2A A single-USIM UE 200 and a multi-USIM UE 205 according to embodiments of the present disclosure are depicted. The UE 200 includes a mobile device ("ME") 210 that has a single USIM 203 registered for use at a time, while the multi-USIM UE 205 includes an ME having multiple USIMs (e.g., a first USIM (USIM-1) 207 and a second USIM (USIM-2) 209) registered for simultaneous use. The USIM-1 207 and the USIM-2 209 may be associated with the same PLMN or different PLMNs. Additionally, the USIM-1 207 and the USIM-2 209 may be associated with different network slices of the same PLMN. Note that both the USIM-1 207 and the USIM-2 209 can be used for idle mode network connections simultaneously.

[0066] Each ME 210 (e.g., transceiver or modem) includes (1) one or more mobile terminals (MT) 215 dedicated to managing the PLMN access interfaces (3GPP or non-3GPP); and (2) one or more terminal equipment (TE) 220 functions required for user operation of the access protocol. Note that the UE 200 and multi-USIM UE 205 may implement the Universal Subscriber Identity Module (“USIM”, sometimes referred to as Subscriber Identity Module, “SIM”) as an integrated circuit or card that needs to be inserted into the UE, and / or as an embedded SIM (“eSIM”) or embedded universal integrated circuit card (“eUICC”) - in the form of a programmable SIM directly embedded in the device.

[0067] Figure 2B The protocol stack 225 of the multi-USIM UE 205 is depicted. The protocol stack 225 includes an upper layer 227 (e.g., IP layer, transport (UDP, TCP) layer, etc.). The protocol stack 225 includes a 5GS session management (“5GSM”) sublayer 229 and a 5GS mobility management (“5GMM”) sublayer 231, which include the NAS layer 230. Note that the AMF 143 includes the NAS layer and can establish a NAS signaling connection with the multi-USIM UE 205. The AS layer 232 (also referred to as “radio protocol”) of the protocol stack 225 includes the RRC layer 233, service data adaptation protocol (“SDAP”) layer 235, PCDP layer 237, RLC layer 239, MAC layer 241, and PHY layer 243 (baseband). The RAN node (e.g., base station unit 121) includes a corresponding AS layer and can establish an AS signaling connection with the multi-USIM UE 205.

[0068] Note that the multi-USIM UE 205 (e.g., the ME 210 part of the multi-USIM UE 205) needs to implement at least as many NAS protocol stacks and radio protocol stacks (e.g., abbreviated as NAS / RP stacks) as the number of USIMs that can be simultaneously registered to the same or different PLMNs. In Figure 2B there are two NAS / RP stacks and two USIM cards / profiles. Note that each NAS / RP stack has its own receiver (e.g., the first receiver (“Rx-1”) 247 for USIM-1 207 and the second receiver (“Rx-2”) 249 for USIM-2 209), but the multi-USIM UE 205 has a single transmitter 245. The transmitted and received signals are conveyed via a duplexer 251 and an antenna 253.

[0069] The different NAS / RP stacks serving different USIMs need to have the ability to exchange the states of other protocol stacks. For example, if the protocol stack of USIM-1 207 wants to initiate a transition from the idle state to the connected state, the protocol stack of USIM-1 queries the state of USIM-2 209. There can be various behavioral scenarios.

[0070] For example, if the connected state of USIM-2 209 is connected (e.g., the ECM / CM connected state at the 5GMM NAS level 231), and if the USIM-2 209 application is configured with a higher priority (or the user decides to maintain communication via USIM-2 209 and ignores the communication trigger of USIM-1 207), then the protocol stack of USIM-1 does not initiate the action of activating the connection, that is, the protocol stack of USIM-1 remains in the idle state and indicates to the application that connection establishment is currently impossible. For example, the multi-USIM UE 205 can display a prompt to the user asking whether to interrupt (e.g., temporarily pause) the active services or applications of USIM-2 209 in order to accept a new connection (e.g., service / application) of USIM-1 207. In addition, the user can be prompted whether the USIM-1 service / application should always be able to interrupt the USIM-2 service / application. In other configurations, this user-specified priority can be stored in the multi-USIM UE 205, for example, to allow automatic pausing of services / applications.

[0071] In another example, if the connected state of USIM-2 209 is connected (e.g., the ECM / CM connected state at the 5GMM NAS level 231), and if the USIM-2 209 application is configured with a lower priority (or the user decides to maintain communication via USIM-2 209 and ignores the communication trigger of USIM-1 207), then the protocol stack of USIM-1 can request the protocol stack of USIM-2 to pause the ongoing connection. After pausing the connection with USIM-2 209, the protocol stack of USIM-2 indicates (e.g., using an internal device in the remote unit) the paused connection to the protocol stack of USIM-1, so that the protocol stack of USIM-1 can initiate connection establishment. Note that if the connected state of USIM-2 is idle (e.g., the ECM / CM idle state at the 5GMM NAS level), then the inter-SIM priority is irrelevant because the protocol stack of USIM-1 can continue to establish the connection.

[0072] As described above, a UE supporting multiple SIMs can operate in a passive mode, a DSDS mode, or a DSDA mode. In the passive mode, the UE simply uses a single USIM at any given time, i.e., no more than a single USIM is ever registered in the network. Therefore, from the perspective of 3GPP, a UE in the passive mode is not considered a multi-USIM UE 205. Additionally, the DSDA mode is a scenario where each USIM has a dedicated ME 210 (such as a transceiver or a modem) for each USIM. Therefore, according to the present disclosure, a UE in the DSDA mode does not fall within the scope of the multi-USIM UE 205.

[0073] Therefore, the multi-USIM UE 205 operates in the DSDS mode. Two DSDS sub-modes are introduced here: In the multi-USIM single-active ("MUSA") mode, it is an operating mode of the multi-USIM UE 205 in which at most one USIM can be used for the connected mode at any given time; in the multi-USIM multi-active ("MUMA") mode, it is an operating mode of the multi-USIM UE 205 in which a subset of multiple UEs (e.g., M USIMs) can be used for the connected mode (N connected modes) at any given time. The relationship between M and N is M > N.

[0074] Compared with a traditional UE (e.g., UE 200), the multi-SIM UE 205 supports at least two different levels of connection suspension states. One possible criterion for differentiating the suspension states can be the duration of the suspension. For example, depending on the (estimated) duration for which the multi-SIM UE 205 is active in the target system (e.g., using USIM-1 207), another system (USIM-2 209) can suspend the current active connection for a short time (e.g., a short suspension state, completed at the RRC layer 233) or for a long time (e.g., a long suspension state, completed at the NAS layer). In contrast, a traditional UE only supports a single suspension state (e.g., at the NAS level).

[0075] The multi-SIM UE 205 determines which type of suspended connection to use when suspending the connection of one USIM (e.g., USIM-1 207) in order to establish a connection to USIM-2 209. In various embodiments, there are at least two types of suspended connections: a) a long suspended connection, in which the NAS protocol exchange between the multi-SIM UE 205 and the CN 140 is used to suspend the active connection; or b) a short suspended connection, in which the AS context is maintained in the multi-SIM UE 205 and the RAN node without supporting radio transmission. An example of a long suspended connection is described in the international patent application PCT / EP2017 / 076410, published as WO 2019 / 076439, which is incorporated herein by reference.

[0076] Regarding the characteristics of the short pause connection state, the serving RAN node maintains the UE AS context (security context, bearer context, etc.) and the multi-SIM UE 205 maintains its AS context. In various embodiments, the state of the multi-SIM UE 205 can be 1) RRC connected or 2) RRC inactive, but importantly with disabled transmissions (i.e., disabled DL transmissions from the perspective of the RAN, or disabled UL transmissions from the perspective of the UE). It can enter the short pause connection state even if there is ongoing communication at, for example, the PDCP layer and / or buffered packets for transmission. In this case, the transmission can be incomplete, the PDCP packets can be interrupted, and the packets can be buffered during the duration of the short pause connection state. The short pause connection state can be entered upon explicit signaling requested by the multi-SIM UE 205. In some embodiments, when implementing the short connection pause of the USIM-1 207, the multi-SIM UE 205 is in the RRC connected state and does not trigger a radio link failure (“RLF”) to the upper layers (e.g., NAS, PDCP, SDAP).

[0077] In certain embodiments, the short pause state is similar to the RRC_INACTIVE state described in 3GPP TS 38.300, but with other differences such as no transmission availability. In the short pause state, the RAN node knows that the multi-SIM UE 205 is not available for DL transmission. The RAN node knows that the multi-SIM UE 205 cannot transmit data / signaling, for example, due to active communication with other USIMs. The RAN node does not perform the RAN paging process, and the RAN node does not allocate a RAN notification area (RNA). The RAN node may or may not notify the core network (e.g., AMF or SMF) of the activation of the short pause state of a given UE. For example, the RAN node may not notify the core network due to one or more of the following reasons: 1) because the duration of the short pause state does not affect the NAS timers for NAS message retransmission running in, for example, the AMF or SMF, or 2) because there is no established DRB with latency-critical or high-reliability QoS flows (e.g., for URLLC, or emergency or priority services). If the UE requests a short pause state transition (e.g., by sending an RRC connection release request) and the RAN node rejects the transition to the short pause state, as a subsequent action, the UE can request a transition to the long pause state (e.g., by sending a NAS MM request message) to the core network (e.g., AMF or MME). In the case where the AMF has requested an explicit notification during the transition from the idle to the connected state (e.g., during the UE initial context establishment process from the AMF / MME to the RAN node), the RAN node can notify the core network (e.g., AMF or SMF) of the short pause state.

[0078] Alternatively, the short pause state can be the RRC_INACTIVE state where radio transmissions are disabled. Here, if DL packets arrive at the RAN node, the RAN node will buffer them, e.g., at the PDCP layer. If the buffer is full, the RAN node discards the packets. In other words, the short pause state can be described as similar to a radio link failure (RLF) condition, but instead of the RAN node and the multi-SIM UE 205 implicitly detecting the RLF, it is requested by explicit RRC signaling from the multi-SIM UE 205. From the UE's perspective, the multi-SIM UE 205 also maintains the AS context (security context, DRB context, etc.), but when UL data arrives, the multi-SIM UE 205 does not request resources for UL transmission. The multi-SIM UE 205 can buffer UL packets, e.g., in the PDCP layer, and if the buffer becomes full, discards the packets.

[0079] Although Figure 3 、 Figures 4A to 4B and Figures 5A to 5B the processes are described under the assumption that the UE is operating in the MUSA mode, note that these solutions can also be applied to UEs operating in the MUMA mode.

[0080] Figure 3 FIG. 300 depicts a flow chart describing the behavior of a multi-SIM UE pausing the connection of one SIM during multi-SIM operation in accordance with an embodiment of the present disclosure. In various embodiments, the processes described in flow chart 300 can be implemented by the multi-SIM remote unit 105 and / or the multi-USIM UE 205.

[0081] The process starts at step 1 where the multi-SIM UE 205 registers / attaches to USIM-1 207 and USIM-2 209 (see block 305). Additionally, for USIM-2 209, the multi-SIM UE 205 enters the CM connected state. In various embodiments, the multi-SIM UE 205 exchanges the supported M-USIM capabilities with the network. This can include indicating whether only a single suspended state (e.g., long suspended state at NAS) is supported or whether multiple suspended states (e.g., long suspended state at NAS and short suspended state at AS) are supported. In various embodiments, the network (e.g., RAN node or MME / AMF) can reply with a configuration (or preference) on which suspended mode (e.g., single suspended state or multiple suspended states) to use. If the network does not send the M-USIM capabilities or M-USIM preference, the UE can conclude that the network does not support M-USIM capabilities, and the UE will initiate any process for the long suspended state (e.g., at NAS) or short suspended state (at RRC). Flowchart 300 assumes that multiple suspended states are supported at the multi-SIM UE 205 and the network.

[0082] At step 2, the multi-SIM UE 205 detects a trigger event to suspend the active connection with USIM-2 209 (see block 310). Recall that if the trigger event is for a service with a higher priority than the application or service corresponding to the active connection of USIM-2 209, the service or application of USIM-1 207 can trigger the suspension. Additionally, the multi-SIM UE 205 determines whether to apply a short connection suspension (i.e., enter the short suspended connection state) or a long connection suspension (i.e., enter the long suspended connection state) (see block 315).

[0083] For example, if the multi-SIM UE 205 is paged for USIM-1 207 and if based on the paging cause value, the multi-SIM UE 205 determines that the MT communication for USIM-1 207 will be short (e.g., less than 1 to 2 seconds), then the multi-SIM UE 205 can decide to enter the short suspended connection state for USIM-2 209. Otherwise, if the paging cause value does not indicate short MT communication, the multi-SIM UE 205 can decide to enter the long suspended connection state for USIM-2 209. Otherwise, if the MT communication trigger event for USIM-1 207 indicates a service with a lower priority than the ongoing service for USIM-2 209, the UE can decide to continue the communication with USIM-2 209 and the UE does not respond to the paging for USIM-1 207.

[0084] During step 3 of determining whether to apply a short pause state or a long pause state, the multi-SIM UE 205 can consider whether a Guaranteed Bit Rate (GBR) QoS flow or bearer is used for the USIM-2 209 connection. One possible behavior could be that if a GBR flow is in place (or there is a QoS flow that requires low latency and / or high reliability, e.g., a URLLC QoS flow), then the multi-SIM UE 205 can determine to apply the long pause state (independent of the possible MT communication duration of USIM-1 207). If there are only non-GBR flows, the multi-SIM UE 205 can determine whether to apply the short pause state or the long pause state based on the estimated duration of the service type of USIM-1 207. Another possible behavior could be that if the active connection with USIM-2 209 corresponds to an emergency service or other (multimedia) prioritized service (MPS), then USIM-1 207 is not allowed to interrupt (e.g., trigger a pause) USIM-2 209.

[0085] In some embodiments where the timer value for the short pause state is known at the point of step 3 (e.g., the timer value is broadcast in the system information broadcast or received during the registration / attachment process), the value of the timer can affect whether the UE decides to enter the short pause state or the long pause state. For example, if the timer value is 1 second and the triggering event of USIM-1 207 in step 2 is an SMS service, then the UE can decide to enter the long pause state because the UE can assume that the concatenated SMS transmission may take more than 1 second. However, if the triggering event of USIM-1 207 in step 2 is a tracking area update or registration (including periodic and mobility-triggered updates) process, then the UE can decide to enter the short pause state because the UE can assume that such signaling processes may take less than 1 second.

[0086] In step 4, assuming that the short connection pause is selected, the multi-SIM UE 205 thus performs the AS / RRC procedure for the short connection pause of USIM-2 209 (see box 320). Refer to Figure 4A This AS / RRC procedure is described in further detail.

[0087] After the MT communication with USIM-2 209 ends, the UE indicates a Release Auxiliary Indication (RAI) to the PLMN2 in order to return to the USIM-1 207 network as soon as possible (ASAP). The RAI allows for a faster transition to the idle state of USIM-2 209. The exchange between the protocol stack of USIM-1 207 and the protocol stack of USIM-2 209 is as Figure 3 described.

[0088] The UE performs an RRC connection modification for USIM-1 207 (i.e., PLMN1) to resume the suspended connection (e.g., reactivate radio transmission). After the UE resumes the radio connection, for example, after the UE performs step (7), the RAN node attempts to transmit any buffered DL packets. Any lost packets can be recovered through application layer transmission. Similarly, the multi-SIM UE 205 can buffer UL packets in, for example, the PDCP layer, and after the radio connection is resumed, for example, after the UE performs step (7), the UE attempts to transmit the buffered UL packets.

[0089] In step 5, the UE and the network (e.g., RAN node) are in a short suspension state where the AS context is preserved (see box 325). Additionally, there may be a timer running for state transition. This timer value can be negotiated during step 4 of the process of entering the short suspension state (e.g., the network / RAN node can send the timer to the multi-SIM UE 205 in a response message).

[0090] For example, the timer value for the short suspension state can be 3 seconds. The timer starts running in the multi-SIM UE 205 and the RAN node when entering the short suspension state. If the timer expires, the network (e.g., RAN node) and the multi-SIM UE 205 can transition to the long suspension state. On the UE side, if the timer expires before the communication of USIM-1 207 ends (see box 330), the multi-SIM UE 205 can transition to the long suspension state (see box 340). In some embodiments, this transition is implicitly completed in the multi-SIM UE 205 (i.e., without signaling to the network) by deleting the AS context and indicating a suspended connection (long suspension) to the NAS layer. On the network side, the RAN node can perform the UE AS context release and access network (AN) connection release procedures (e.g., clause 4.2.6 of TS23.502).

[0091] If the communication of USIM-1 207 ends before the timer expires, the multi-SIM UE 205 transitions out of the short connection suspension and resumes the connection of USIM-2 209 (see box 335). The resumption of the connection is discussed in further detail below with reference to Figure 4B and Figures 5A to 5B After resuming the connection, the multi-SIM UE 205 is in the normal state of USIM-2 209 (e.g., CM connection state) (see box 360).

[0092] If the multi-SIM UE 205 selects long connection suspension, then at step 9, the UE performs the NAS MM procedure for the long suspension of USIM-2 209 (see box 345). As discussed here, the long suspension connection includes deleting the AS context at both the UE and the RAN node. At step 10, for USIM-2 209, the multi-SIM UE 205 remains in the long connection suspension state until the communication of USIM-1 207 ends (see box 350).

[0093] At step 11, at the end of the communication of USIM-1 207, the multi-SIM UE 205 performs the NAS MM procedure to resume the connection of USIM-2 (see box 355). The resumption of the connection is discussed in further detail with reference to Figure 4B and Figures 5A to 5B At step 12, after resuming the connection, for USIM-2 209, the multi-SIM UE 205 is in the normal state (e.g., CM connection state) (see box 360).

[0094] Although Figure 3 examples of two different suspension states (e.g., short suspension state and long suspension state) are shown, the present disclosure is not limited to two states. Generally, there can be multiple suspension states and means for transitioning between states such as a short suspension state, an intermediate suspension state, and a long suspension state.

[0095] Figures 4A to 4B Process 400 depicts a scenario of a suspended connection of one USIM (e.g., USIM-1) according to an embodiment of the present disclosure. Process 400 introduces an AS protocol (e.g., RRC procedure) to implement signaling for radio transmission suspension. Process 400 involves UE 205, (R)AN-2 / AMF-2 entity 405, (R)AN-1 node 410, AMF-1 415, and SMF-1 / UPF-1 entity 420. Although (R)AN-2 / AMF-2 405 is depicted as a combined entity, in various embodiments, AMF-2 is not co-located with (R)AN-2. (R)AN-2 / AMF-2 405 is part of the PLMN2 registered by USIM-2, while the entities (R)AN-1 node 410, AMF-1 415, and SMF-1 / UPF-1 420 are part of the PLMN1 registered by USIM-1. Similarly, although SMF-1 / UPF-1 420 is depicted as a combined entity, in various embodiments, SMF-1 is not co-located with UPF-1.

[0096] In Figure 4A, process 400 starts at step 0, at which time UE 205 registers (or attaches) to one or more mobile communication networks using multiple SIMs (e.g., USIM-1 and USIM-2, see signaling 421). When registering to more than one USIM (e.g., in the case where UE 205 has already registered to USIM-1 and initiated registration to USIM-2), UE 205 performs NAS MM procedures (e.g., registration request or TAU procedure) to indicate its multi-SIM (“MuSIM”) capability to each network (i.e., for each active USIM). This can be indicated, for example, in a NAS MM message to a network service node (e.g., AMF / MME). MuSIM UE capabilities can include: 1) MuSIM support: (e.g., yes / no), 2) suspended state support: (e.g., long suspended state, and / or short suspended state, etc.), and / or 3) release assistance information (“RAI”) support for CP transmission, SMS transmission, and / or UP transmission. This support for RAI may help determine fast termination of control plane transmission in the network (e.g., in a RAN node or in the AMF). For example, a RAN node typically will have a so-called “inactivity timer” with a value (e.g., 10 seconds), which is triggered by UL / DL data. Thus, if the inactivity timer of the UE expires because data is not sent or received over a radio bearer (e.g., signaling bearer and / or data bearer), the RAN node can place the inactive UE in the idle state. The access stratum RAI (“AS-RAI”) indication from the UE lets the RAN node know that it can immediately place the UE in the idle state (e.g., at the RRC layer), rather than waiting for the inactivity timer to expire. Similarly, the non-access stratum RAI (“NAS_RAI”) indication from the UE lets the AMF know that it can immediately place the UE in the idle state (e.g., at the NAS layer), rather than waiting for the inactivity timer to expire.

[0097] Note that in one embodiment, UE 205 sends MuSIM information only when the second USIM is activated (which can be a manual activation). Note that in the above description, the MuSIM UE capability indication in the NAS MM message means a) UE205 supports as Figure 3The MuSIM mechanism described above, and b) both because multiple USIMs are activated in UE 205, UE 205 wishes to use (i.e., request) the MuSIM mechanism (i.e., UE 205 registers with multiple USIMs). In other words, if UE 205 registers to use multiple USIMs, UE 205 can determine to send a MuSIM UE capability indication in the NAS MM request message. In an alternative approach, UE 205 can also send two different indications to the network, one regarding MuSIM UE capability and the other regarding the required MuSIM. In one example, the latter indication (required MuSIM) will mean to the network that the network should be reconfigured internally to start sending service / traffic type indications in the paging message for this UE 205. Note that from the network's perspective, MuSIM feature / enhancement support means that the network supports at least the following devices: 1) sending service / traffic type indications in the paging message and / or 2) transitioning to a long pause state and / or a short pause state.

[0098] Similar to the UE indication, a network function (such as AMF or MME) can indicate a preferred (or supported) operating mode in the NAS MM response message (such as a registration acceptance or an attachment acceptance message). If A) UE 205 has indicated MuSIM support capability in the NAS MM request message, and B) based on the network policy / configuration and subscription type associated with UE 205, the network (such as AMF or MME) can decide to send an indication regarding the preferred MuSIM mode. If UE 205 has previously indicated MuSIM support capability and the network has enabled / applied MuSIM enhancements to the UE's registration, but in a consecutive NAS MM procedure, UE 205 does not include MuSIM support capability, or UE 205 includes an explicit indication that MuSIM support is no longer required, this will mean that UE 205 may have deactivated a USIM card and from now on UE 205 operates in a single USIM mode. In this case, the network (such as AMF or MME) can delete the previously stored MuSIM support from the UE context, and the network does not include MuSIM preferences in the NAS MM response message. During the deregistration or detachment process, the network can delete the stored MuSIM support capability in the UE context stored in the AMF / MME.

[0099] The network (e.g., AMF or MME) may send a network indication to the UE in a NAS MM response (e.g., registration acceptance message), and the network indication may include, for example: 1) MuSIM preference / support: (e.g., yes / no), 2) preference / support for suspended states: (e.g., long suspended state and / or short suspended state, and / or preferred duration of short suspended state, etc.), and / or 3) support for release assistance information (“RAI”) for CP transmission, SMS transmission, and / or UP transmission. If the network does not send a MuSIM preference or MuSIM support indication to the UE 205 (e.g., an indication included in a reply message to the UE-requested NAS MM procedure), the UE205 concludes that the network does not prefer or support the MuSIM feature / enhancement, and the UE determines not to apply the MuSIM feature / enhancement (i.e., the UE will not initiate any procedures for long or short suspended states. In this sense, when using the current registration in this PLMN, the network (e.g., AMF or MME) can determine whether the UE applies the MuSIM feature / enhancement and / or the appropriate configuration of the mechanism for long or short suspended connection states and / or other parameters required for MuSIM enhancement (e.g., the time of short suspended connection state).

[0100] It is possible that one network serving USIM-1 (e.g., PLMN-1 including (R)AN-1 node 410, AMF-1 415, and SMF-1 / UPF-1) supports MuSIM capabilities or wants to apply MuSIM features, while another network serving USIM-2 (e.g., PLMN-2 including (R)AN-2 / AMF-2 405) does not support MuSIM capabilities (or does not want to apply MuSIM features). In this case, the UE 205 can apply the solution for connection suspension and recovery to PLMN-1, as Figure 3 described in steps 3 and 6 below, but the UE 205 will trigger the procedures for connection suspension and recovery for MO services. The UE 205 knows that the trigger for MT services will not include the service / traffic type in the MT request (e.g., paging) message. Note that the network may decide to apply the MuSIM feature / enhancement based on the network operator's policy or configuration. For example, the network may decide to enable / apply MuSIM enhancements for non-roaming UEs but not for roaming UEs. In another example, the network may decide to apply MuSIM enhancements to high-configured subscribers (e.g., gold or silver members) but not to low-configured subscribers (e.g., bronze members or prepaid users). It is beneficial if both network PLMN1 and PLMN-2 apply MuSIM enhancements to obtain all the advantages of this solution, but there may still be some / partial advantages if only one of the multiple networks applies MuSIM enhancements.

[0101] During the UE initial context setup procedure or the UE context modification procedure, the network (e.g., AMF or MME) may send a configuration indication to the RAN node (e.g., gNB or eNB) regardless of whether the UE is allowed to enter the short pause state. If the UE sends such a request in step 3a-1, this indication will help the RAN node determine whether to apply the short pause state (see signaling 431). For example, if the AMF / MME does not include an indication allowing (or supporting) the short pause state, then according to step 3a-1, the RAN node should reject the UE's request to transition to the short pause state. Procedure 400 assumes that (after registration / attachment) UE 205 is in a connected state (e.g., CM connected state) for USIM-1 and in an idle state (e.g., ECM / CM-idle state) for USIM-2 (see box 423). In step 1a, UE 205 receives a core network (CN) initiated paging message for USIM-2 209 (see signaling 425), where the paging message may include additional paging information indicating the type of service (or traffic) that causes the MT communication, i.e., the paging procedure. The granularity of the paging information can be distinguished between the following service categories: a) IMS-based and non-IMS-based voice / video services; b) IMS-based and non-IMS-based SMS or USSD; c) IMS services other than voice / video or SMS; and / or d) other services not listed above, such as data services including video.

[0102] In step 1b, alternatively, the trigger for communication of USIM-2 209 can be mobile originated (MO) communication (see box 427). The upper layer in UE 205 needs to indicate additional information about the service / traffic type to the NAS layer so that the NAS layer can make decisions regarding service priority and service duration. In the prior art, the NAS layer may only know which PDU session (e.g., IMS PDU session) will be activated, but whether the service on IMS is voice, video, or SMS may be invisible to the NAS layer. Therefore, UE enhancements are needed to indicate the service / traffic type to the NAS layer, similar to the additional paging information for MT communication in step 1a.

[0103] In step 2, based on the service type in the paging cause in step 1a - or based on the type of MO communication in step 1b - and based on the supported or preferred capabilities from step 0, UE 205 determines whether to apply a short pause connection or a long pause connection (see box 429). Refer to Figure 3 for a discussion of how UE 205 determines which type of pause connection to apply.

[0104] In step 3, the UE 205 applies a connection suspension mechanism to the USIM-1 application. For example, step 3a shows the UE procedure for applying a short suspension connection (also known as "short connection suspension", see group 430), while step 3b shows the UE procedure for applying a long suspension connection (also known as "long connection suspension", see group 440).

[0105] In step 3a-1, if the UE 205 determines to apply a short suspension connection, the UE 205 performs an RRC procedure to request entry into the short suspension connection state or release the RRC connection with a specific indication (e.g., "unavailable indication") of the requested short suspension connection state (see signaling 431). Note that the "unavailable indication" can be used to distinguish that this RRC request is for a new short suspension connection state, rather than for the known suspension connections enhanced for cellular IoT in 4G and 5G. In some embodiments, the UE 205 may send a dedicated RRC message, such as an RRC suspension request message or an RRC connection release request message, to request the network (e.g., a RAN node) to suspend the RRC connection and transition to the short suspension connection state. In other embodiments, existing RRC messages can be used, and the UE includes a specific indication (e.g., a new information element, IE), such as "no transmission" or "temporarily unavailable" or "connection release due to the activity of another USIM", or some similar indication. In the UE, sending an RRC connection release / suspension request is a new trigger, i.e., this trigger is due to the need to establish a connection for another USIM, different from other known triggers for connection release in the UE (i.e., due to power consumption reduction or UE radio capability change). This instructs the PDCP layer in the (R)AN-1 node 410 on the network side to stop sending DL PDUs and buffer the upper layer PDUs. See Figure 3 the detailed description of the short suspension connection state in the description.

[0106] In step 3a-2, the (R)AN-1 node 410 replies with an RRC suspend response message, which can indicate a positive or negative response (see signaling 433). For example, in step 3a-2, an existing RRC message, the RRCConnectionRelease message, can be used together with a short connection suspend indication (which should teach the UE about the type of short connection suspend state). In various embodiments, the RRC suspend response message includes at least one of the following indications: 1) a timer value for transitioning to a stable suspend state; and / or 2) the type of stable state. Examples of stable states can include a long-duration suspended connection, the RRC-inactive state, and / or the ECM / CM-idle state. Note that a short suspended connection state (e.g., "temporarily unavailable") is considered an "unstable" state because the UE 205 is considered available to the NAS layer but not to the RRC / AS layer. If the RRC suspend response indicates rejection of the short suspended state (i.e., a negative response), then according to step 3b, the UE can determine to initiate the process for a long suspended state (see signaling 440).

[0107] In step 3a-3, the (R)AN-1 node 410 maintains the UE context (security, bearer context, N2 and N3 connections). However, the (R)AN-1 node 410 stops DL transmission (e.g., disables sending DL PDUs and instead buffers DL PDUs in the PDCP layer, for example, see box 435). This state can also be described as the RRC_INACTIVE state where radio transmission is disabled. Additionally, the UE 205 also maintains the UE context but stops UL transmission (e.g., disables sending UL PDUs and optionally buffers UL PDUs in the PDCP layer, for example, see box 437). In various embodiments, if there is a GBR bearer, a short suspension is not applied. In the case of a GBR flow / bearer, the UE 205 can determine to apply a long suspended state.

[0108] Continue Figure 4B , in step 3b, if the UE 205 determines to apply a long suspended connection (e.g., based on a paging message or the service type in an MO service trigger), then the UE 205 performs a NAS MM procedure (e.g., a service request procedure) to notify the serving node (e.g., AMF-1 415) that a connection suspension is needed (see signaling 441).

[0109] In step 4, the UE 205 performs connection establishment to the USIM-2 (see signaling 443). For example, the UE 205 performs a service request procedure to the network (e.g., (R)AN-2 / AMF-2 405) to perform control plane transmission or user plane connection activation (PDU session or PDN connection activation).

[0110] In step 5, for the case of control plane transmission, UE 205 may send release assistance information (“RAI”) for USIM-2, such as AS-RAI (e.g., to RAN-2) or NAS-RAI (see signaling 445) included in a NAS message. This indication may be determined in UE 205 based on the knowledge that there is no longer expected UL / DL data in UE 205. The RAI indication is beneficial for transitioning to the idle state as soon as possible.

[0111] In step 6, UE 205 resumes the connection to USIM-1. For example, in step 6a-1 where a short pause connection is applied (and the timer has not expired), UE 205 performs an RRC connection resume procedure (see signaling 447). Here, UE 205 may use the existing RRC message RRCConnectionResumeRequest message and optionally may include an indication that UE 205 is available again, or may indicate whether UL data is incomplete and request UL resources. Alternatively, UE 205 may use an RRC modification procedure, e.g., send an RRC modification request message to request USIM-1, which may include parameters or indications that UE 205 is available again for transmission. Further, in step 6a-2, the network (e.g., (R)AN-1 node 410) may reply with an RRCConnectionResume message to activate the suspended SRBs and DRBs in the UE and the RAN (see signaling 449). As another example, in step 6b where a long pause connection is applied, UE 205 performs a NAS service request procedure for USIM-1 (see signaling 451).

[0112] After pausing the connection to USIM-1 (e.g., after UE enters the CM idle state of USIM-1, i.e., after step 3b or after the timer expires in step 3a-2), the NAS layer in UE 205 may indicate “interface closed” to the applications that have used the established data session (PDU session). This is beneficial for notifying that the IP connection is no longer available. Once the connection is established again (e.g., after the connection resume procedure in step 6), the NAS layer may notify the applications that the IP connection is available again.

[0113] As described above, UE 205 is capable of maintaining timers for the short pause state (as shown in steps 3a-2 and 3a-3). To configure the timers, one or more of the following mechanisms may be applied: 1) The RAN node sends the timer configuration via a unicast message (e.g., an RRC pause accept / acknowledgment message), 2) The timer configuration is broadcast in the system information (e.g., SIB), and / or 3) The timer configuration is negotiated during a NAS procedure (e.g., a registration procedure or a UE configuration update).

[0114] Known prior art solutions for connection suspension of a USIM (e.g., USIM-1) release the NAS signaling connection and then release the user plane resources resulting in additional signaling between the RAN and the CN for deleting the UE access stratum context in the RAN node and the UE 205, and releasing the N2 and N3 associations. When performing a service request procedure with UP activation, the legacy procedure also results in increased signaling when the UE 205 resumes the connection of USIM-1. However, by introducing a "short suspension connection" state (or RRC_Inactive in the case where radio transmission is disabled), there is more flexibility to briefly suspend radio transmission at the AS layer (by using only AS signaling such as RRC suspension) without the need for additional signaling at the NAS layer.

[0115] Figures 5A to 5B FIG. 500 depicts, in accordance with an embodiment of the present disclosure, a process for generating missed mobile terminal (MT) communication information during connection suspension and sending it to the UE during connection resume. Process 500 involves a multi-SIM UE 205, a (R)AN-1 node 410, an AMF-1 415, an SMF 1 / UPF 1 420, and a UDM 1 49. During connection suspension (i.e., the long suspension state described above), the core network 140 does not attempt to deliver DL data and MT signaling, i.e., the core network does not page the multi-SIM UE 205. However, it is not clear from the legacy procedure what happens to the DL packets in the network during connection suspension. The problem is that when the suspended connection resumes, the multi-SIM UE 205 does not know if it has missed any communication.

[0116] Process 500 shows a solution for handling packets buffered during connection suspension, e.g., by notifying the UE of the activities missed during connection suspension. Process 500 assumes that when the multi-SIM UE 205 establishes a connection to USIM 2 209, the connection of USIM 1 207 is suspended. In some embodiments, the network (e.g., SMF or UPF) may store data packets or MT communication identifiers ("MT communication ID") during the "connection suspension" state. The generalized term "missed MT communication information" is used.

[0117] If the UE has an active connection to USIM-2 209 (e.g., based on service priority inside the UE), after the end of the activity of USIM-2 209, the UE triggers the release of the connection to USIM-2 209 to allow the resumption request of the suspended connection of USIM-1 207. For example, this may be required if the UE is in a CM connection and an RRC inactive state for USIM-2 209 (which is considered an active connection to USIM-2 209). Such a function may be needed because the suspended connection of the USIM may never trigger a paging procedure.

[0118] In some embodiments, after the UE executes NAS MM signaling (e.g., the NAS service request procedure for the USIM-1207 to exit the suspended state), the network sends the stored "missed MT communication information" to the UE. The "missed MT communication information" can be sent to the UE via control plane signaling, e.g., using NAS session management signaling from the SMF to the UE (e.g., NAS N1-SM signaling). As discussed in international patent application PCT / EP2017 / 076410, the UE can use the NAS service request procedure and include a "PDU Session Status" indication to indicate which PDU sessions are still valid for the suspended connection. In certain embodiments, the 5GSM layer 229 of the UE can process this information internally and forward it to the corresponding application. If needed, the application can trigger the establishment of UP resources.

[0119] In Figure 5A , process 500 starts at step 1, and the multi-SIM UE 205 operating in the MUSA mode determines to activate the connection to USIM-2 209 (see block 501). The multi-SIM UE 205 may have exchanged MuSIM capabilities with the network during the NAS MM procedure, as Figure 4A described in step 0. As described above, the multi-SIM UE 205 determines to execute the procedure of suspending the connection of USIM-1 207 (i.e., all established PDU sessions). For USIM-1 207, the UE transitions to the CM idle and suspended state. In certain embodiments, the UE can use new parameters (or information elements, IEs) to notify the network of the reason for suspension and additionally the suspension duration.

[0120] In step 2, the network serving USIM-1 207 (i.e., AMF-1, SMF-1, UPF-1, etc.) executes the procedure of suspending the existing connection (see block 503). Here, the AMF can indicate one or more of the following parameters to the SMF in the signaling for suspending the PDU session (note that the AMF performs this step for each PDU session active during the connection suspension): 1) the reason for the PDU session suspension or the reason for the UP release (e.g., the suspended connection); 2) the unreachable time, indicating the time when the SMF should not attempt DL communication; 3) the suspended paging request: meaning that if DL data 505 arrives, the SMF should not send paging request signaling; and / or 4) information on whether the SMF should store DL data activity during the suspended connection. For example, the SMF can collect MT communication information (e.g., DL packets or store the MT communication ID, the source address of the communication initiator).

[0121] In step 3, the multi-SIM UE 205 determines to perform connection recovery for USIM-1 207 (see box 507). For example, the connection with USIM-2 209 has been released. In step 4, the multi-SIM UE 205 performs a service request procedure (see signaling 509). There can be a clear indication that this procedure is for restoring the old connection, i.e., the multi-SIM UE 205 is available again for DL communication.

[0122] In step 5, AMF-1 415 resumes all PDU sessions that were previously suspended (considering the PDU session status IE, see box 511). In step 6, the network (e.g., SMF-1) can perform one of the following options:

[0123] Step 6a, if SMF-1 / UPF-1 420 has buffered DL packets, SMF-1 can activate the user plane resources and deliver the buffered packets (see box 513). Note that the buffered DL packets are transmitted via the user plane resources, i.e., the N3 connection and the DRB.

[0124] Step 6b, if SMF-1 / UPF-1 420 has stored the missed MT communication information, SMF-1 sends an N1-SM message (e.g., 5GSM status message) that includes the missed MT communication information (e.g., MT communication ID, e.g., IP address or application initiator ID, or buffered packets; see box 515 and signaling 517). Note that the MT communication information can be transmitted via the control plane signaling connection.

[0125] In step 7, if the multi-SIM UE 205 receives the MT communication information, the multi-SIM UE 205 internally triggers the application identified by the MT communication information (see box 519).

[0126] In step 8, the multi-SIM UE 205 can perform a service request procedure to establish user plane resources for the PDU session associated with the application identified by the MT communication information in step 7 (see signaling 521).

[0127] The benefit of the solution of procedure 500 is that when the connection is suspended, the multi-SIM UE 205 is informed of the missed mobile terminated communication. This solution can be used for applications (or PDU sessions) that do not automatically contact the application server when the IP connection becomes available again (after being unavailable previously).

[0128] In an alternative solution of process 500, after restoring the connection for a specific USIM, i.e., the USIM can use the radio transmission capabilities of the UE, the protocol stack associated with the USIM can indicate to the UE application that the IP connection is available again. Then, the UE application can contact the corresponding application server (AS) and check if there are any missed activities while the UE application was unable to communicate due to the suspended connection.

[0129] Figure 6 An embodiment of a user equipment device 600 according to an embodiment of the present disclosure is depicted. The user equipment device 600 can be used to suspend the connection of one SIM during multi-SIM operation. The user equipment device 600 can be an embodiment of the remote unit 105. Additionally, the user equipment device 600 can include a processor 605, a memory 610, an input device 615, an output device 620, and a transceiver 625. In some embodiments, the input device 615 and the output device 620 are combined into a single device, such as a touch screen. In certain embodiments, the user equipment device 600 does not include any input device 615 and / or output device 620.

[0130] As shown, the transceiver 625 includes at least one transmitter 630 and at least one receiver 635. Here, the transceiver 625 communicates with a mobile core network (e.g., 5GC) via an interworking function (e.g., TNGF or N3IWF) and through a non-3GPP access network. Additionally, the transceiver 625 can support at least one network interface 640. Here, the at least one network interface 640 facilitates communication with an eNB or gNB (e.g., using the "Uu" interface). Additionally, the at least one network interface 640 can include interfaces for communicating with a UPF, an SMF, and / or a P-CSCF.

[0131] The user equipment device 600 includes multiple SIMs. In some embodiments, the user equipment device 600 includes a first SIM 645 registered with a first mobile communication network and a second SIM 650 registered with a second mobile communication network.

[0132] In one embodiment, the processor 605 can include any known controller capable of executing computer-readable instructions and / or capable of performing logical operations. For example, the processor 605 can be a microcontroller, a microprocessor, a central processing unit ("CPU"), a graphics processing unit ("GPU"), an auxiliary processing unit, a field-programmable gate array ("FPGA"), or a similar programmable controller. In some embodiments, the processor 605 executes instructions stored in the memory 610 to perform the methods and routines described herein. The processor 605 is communicatively coupled to the memory 610, the input device 615, the output device 620, and the transceiver 625.

[0133] In various embodiments, the processor 605 receives a communication trigger associated with the first SIM 645, the communication trigger indicating a service type. Here, when the second SIM 650 has an active connection (e.g., the user equipment device 600 is in a CM connected state for the second SIM 650), the communication trigger is received. In one embodiment, the communication trigger is an indication of a mobile terminated communication, such as a paging request. In another embodiment, the communication trigger is an indication of a mobile originated (“MO”) communication, such as an indication from an internal application of data to be transmitted.

[0134] In response to the communication trigger, the processor 605 determines whether to apply a short connection suspension or a long connection suspension to the second SIM, the determination being based on the service type. For example, an MT paging message indicating a short message service (“SMS”) service type may trigger a short connection suspension. As another example, an MO tracking area update (“TAU”) message may trigger a short connection suspension.

[0135] In some embodiments, the communication trigger associated with the first SIM 645 is only allowed to interrupt the service (or application) associated with the second SIM 650 if the triggered application or service type associated with the first SIM 645 is configured to have a higher priority than the application or service currently being used with the second SIM 650. In certain embodiments, if the second SIM 650 is participating in an emergency communication session (e.g., the first SIM 645 is not allowed to interrupt the emergency communication service of the second SIM 650), the processor 605 determines not to suspend the connection of the second SIM 650.

[0136] In some embodiments, when determining whether to apply a short connection suspension or a long connection suspension to the second SIM, the processor 605 also considers the bearer type associated with the second SIM 650. In such an embodiment, in response to the second SIM 650 being associated with a guaranteed bit rate (“GBR”) bearer, the processor 605 may determine to apply a long connection suspension.

[0137] In some embodiments, the processor 605 controls the transceiver 625 to exchange the supported M-USIM capabilities with a network (e.g., with a RAN node, an AMF, or an MME). This may include indicating whether only a single suspended state (e.g., a long suspended state at the NAS) is supported or whether multiple suspended states (e.g., a long suspended state at the NAS and a short suspended state at the AS) are supported. In various embodiments, the transceiver 625 receives a reply from the network (e.g., a RAN node or an MME / AMF), the reply containing the configuration (or preference) of which suspended mode to use (e.g., a single suspended state or multiple suspended states). If the network does not send the M-USIM capabilities or M-USIM preferences, the processor 605 may conclude that the network does not support the M-USIM capabilities, as described above with reference to Figure 3 as described.

[0138] The processor 605 selects one of the short connection suspension and the long connection suspension for the second SIM application. In some embodiments, the processor 605 applies the short connection suspension to the second SIM 650 by transmitting an RRC layer suspension request, and applies the long connection suspension to the second SIM 650 by transmitting a NAS layer suspension request. In certain embodiments, applying the long connection suspension to the second SIM 650 includes transitioning to the NAS idle state in response to receiving a suspension response message from the second network. Here, the suspension response message may be an RRC layer message or a NAS layer message. Note that the suspension response message is sent as a response to the NAS layer suspension request message.

[0139] In certain embodiments, applying the short connection suspension includes the processor 605 disabling the transmission for the second SIM 650 in response to receiving an RRC layer suspension response. In certain embodiments, applying the short connection suspension includes the processor 605 maintaining the access stratum context of the second SIM 650.

[0140] In some embodiments, registering the first SIM 645 and the second SIM 650 includes indicating support for one or more of the following parameters: multi-SIM enhancement, short connection suspension, or long connection suspension, receiving a network preference indicating whether to apply multi-SIM enhancement, short connection suspension, or long connection suspension, and configuring the processor to apply multi-SIM enhancement, short connection suspension, or long connection suspension based on the received network preference. In certain embodiments, not receiving any network preference may be interpreted by the UE as an indication that multi-SIM enhancement is not supported in the network (e.g., assume not supported unless a parameter indicating support is received).

[0141] In various embodiments, the processor 605 activates the connection associated with the first SIM 645 in response to pausing the active connection of the second SIM 650. When the active connection of the second SIM 650 is paused, the processor 605 performs the communication corresponding to the communication trigger of the first SIM 645. After that, the processor 605 controls the transceiver 625 to send Release Assistance Information (“RAI”) in response to ending the communication corresponding to the communication trigger, and the release assistance information includes Access Stratum (“AS”) RAI and / or Non-Access Stratum (“NAS”) RAI.

[0142] The processor 605 also resumes the paused connection in the second communication network associated with the second SIM 650 in response to ending the communication corresponding to the communication trigger. In some embodiments, resuming the paused connection includes sending an RRC layer connection resume request (e.g., resuming the short connection pause of the second SIM 650) in response to transmitting an RRC layer pause request and / or sending a NAS layer resume request (e.g., resuming the long connection pause of the second SIM 650) in response to transmitting a NAS layer pause request.

[0143] In some embodiments, the transceiver 625 receives a pause timer value associated with the short connection pause of the second SIM 650. For example, the transceiver 625 may receive a pause response message containing the pause timer value. As another example, the pause timer value may be broadcast in a System Information Block (“SIB”) or negotiated during the NAS registration process. In such an embodiment, the processor 605 may initiate the pause timer in response to receiving an RRC layer pause response, and in response to the expiration of the pause timer, transition the second SIM 650 from a short connection pause to a long connection pause.

[0144] In one embodiment, the user equipment device 600 may initiate application / service level signaling before performing a connection pause process (e.g., for a long pause state or a short pause state). For example, the processor 605 may control the transceiver 625 to notify an application server (or other communication peer) of the temporary unavailability of the device (e.g., due to pausing one USIM to perform communication on another USIM), so that the service or communication exchange can be interrupted (or paused or terminated) in a controlled manner at the application / service layer. This is particularly beneficial in the case of a long pause state when the user equipment device 600 is unavailable for communication for a relatively long time. Another benefit is that the communication peer will stop sending user data packets, and the user plane resources will not be consumed (e.g., buffering and discarding data packets). When the paused USIM resumes / continues, the processor 605 may control the transceiver 625 to notify the application server (or communication peer) that the user equipment device 600 is available for communication again.

[0145] In one embodiment, the memory 610 is a computer-readable storage medium. In some embodiments, the memory 610 includes volatile computer storage media. For example, the memory 610 may include RAM, including dynamic RAM ("DRAM"), synchronous dynamic RAM ("SDRAM"), and / or static RAM ("SRAM"). In some embodiments, the memory 610 includes non-volatile computer storage media. For example, the memory 610 may include a hard disk drive, flash memory, or any other suitable non-volatile computer storage device. In some embodiments, the memory 610 includes both volatile and non-volatile computer storage media. In some embodiments, the memory 610 stores data related to pausing the connection of one SIM during multi-SIM operation, such as storing AS context, SIM status, etc. In certain embodiments, the memory 610 also stores program code and related data, such as an operating system ("OS") or other controller algorithms and one or more software applications operating on the user equipment device 600.

[0146] In one embodiment, the input device 615 may include any known computer input device, including a touch panel, buttons, keyboard, stylus, microphone, etc. In some embodiments, the input device 615 may be integrated with the output device 620, for example, as a touch screen or a similar touch-sensitive display. In some embodiments, the input device 615 includes a touch screen such that text can be input using a virtual keyboard displayed on the touch screen and / or by handwriting on the touch screen. In some embodiments, the input device 615 includes two or more different devices, such as a keyboard and a touch panel.

[0147] In one embodiment, the output device 620 may include any known electronically controllable display or display device. The output device 620 may be designed to output visual, auditory, and / or tactile signals. In some embodiments, the output device 620 includes an electronic display capable of outputting visual data to the user. For example, the output device 620 may include, but is not limited to, an LCD display, an LED display, an OLED display, a projector, or a similar display device capable of outputting images, text, etc. to the user. As another non-limiting example, the output device 620 may include a wearable display, such as a smartwatch, smart glasses, a head-up display, etc. Additionally, the output device 620 may be a component of a smart phone, a personal digital assistant, a television, a desktop computer, a notebook (laptop) computer, a personal computer, a vehicle dashboard, etc.

[0148] In some embodiments, the output device 620 includes one or more speakers for generating sound. For example, the output device 620 can generate an audible alert or notification (e.g., a beep or a buzzer). In some embodiments, the output device 620 includes one or more haptic devices for generating vibrations, movements, or other haptic feedback. In some embodiments, all or part of the output device 620 can be integrated with the input device 615. For example, the input device 615 and the output device 620 can form a touch screen or a similar touch-sensitive display. In other embodiments, all or part of the output device 620 can be located near the input device 615.

[0149] As described above, the transceiver 625 communicates with one or more network functions of the mobile communication network via one or more access networks. The transceiver 625 operates under the control of the processor 605 to transmit messages, data, and other signals, and also to receive messages, data, and other signals. For example, the processor 605 can selectively activate the transceiver (or a part thereof) at a particular time to send and receive messages.

[0150] The transceiver 625 can include one or more transmitters 630 and one or more receivers 635. Although only one transmitter 630 and one receiver 635 are shown, the user equipment device 600 can have any suitable number of transmitters 630 and receivers 635. Additionally, the transmitter 630 and the receiver 635 can be of any suitable type of transmitter and receiver. In one embodiment, the transceiver 625 includes a first transmitter / receiver pair for communicating with the mobile communication network via an authorized radio spectrum, and a second transmitter / receiver pair for communicating with the mobile communication network via an unlicensed radio spectrum.

[0151] In some embodiments, the first transmitter / receiver pair for communicating with the mobile communication network via an authorized radio spectrum and the second transmitter / receiver pair for communicating with the mobile communication network via an unlicensed radio spectrum can be combined into a single transceiver unit, such as a single chip that performs the functions for both the authorized and unlicensed radio spectrums. In some embodiments, the first transmitter / receiver pair and the second transmitter / receiver pair can share one or more hardware components. For example, certain transceivers 625, transmitters 630, and receivers 635 can be implemented as physically separate components that access shared hardware resources and / or software resources, such as, for example, the network interface 640.

[0152] In various embodiments, one or more transmitters 630 and / or one or more receivers 635 may be implemented and / or integrated into a single hardware component, such as a multi-transceiver chip, a system-on-chip, an ASIC, or other types of hardware components. In certain embodiments, one or more transmitters 630 and / or one or more receivers 635 may be implemented and / or integrated into a multi-chip module. In some embodiments, other components, such as network interface 640 or other hardware components / circuits, may be integrated with any number of transmitters 630 and / or receivers 635 into a single chip. In such embodiments, the transmitters 630 and receivers 635 may be logically configured as a transceiver 625 using one or more common control signals, or as modular transmitters 630 and receivers 635 implemented in the same hardware chip or multi-chip module.

[0153] Figure 7 FIG. depicts one embodiment of a network device apparatus 700 according to an embodiment of the present disclosure, which may be used to suspend the connection of one SIM during multi-SIM operation. In some embodiments, the network device apparatus 700 may be an embodiment of a RAN node, such as a base station unit 121 and / or a (R)AN-1 node 410. In other embodiments, the network device apparatus 700 may be an embodiment of an AMF 143, an AMF-1 415, and / or an MME. Additionally, the network device apparatus 700 may include a processor 705, a memory 710, an input device 715, an output device 720, and a transceiver 725. In some embodiments, the input device 715 and the output device 720 are combined into a single device, such as a touch screen. In certain embodiments, the network device apparatus 700 does not include any input device 715 and / or output device 720.

[0154] As shown, the transceiver 725 includes at least one transmitter 730 and at least one receiver 735. Here, the transceiver 725 communicates with one or more remote units 105 and one or more interworking functions 135, which provide access to one or more PLMNs. Additionally, the transceiver 725 may support at least one network interface 740. In some embodiments, the transceiver 725 supports a first interface (e.g., the N2 interface) for communicating with a RAN node, such as a gNB or an eNB, a second interface (e.g., N8, N11, N15, etc. interfaces) for communicating with one or more control plane network functions (e.g., UDM, SMF, PCF) in a mobile core network (e.g., 5GC), and a third interface (e.g., the N1 interface) for communicating with a remote unit (e.g., a UE) via a 3GPP access network or via a non-3GPP access network through the first interface (the N2 interface).

[0155] In one embodiment, processor 705 may include any known controller capable of executing computer-readable instructions and / or capable of performing logical operations. For example, processor 705 may be a microcontroller, a microprocessor, a central processing unit (“CPU”), a graphics processing unit (“GPU”), a co-processing unit, a field programmable gate array (“FPGA”), or a similar programmable controller. In some embodiments, processor 705 executes instructions stored in memory 710 to perform the methods and routines described herein. Processor 705 is communicatively coupled to memory 710, input device 715, output device 720, and first transceiver 725.

[0156] In various embodiments, network device apparatus 700 may operate as a RAN node—e.g., a gNB or an eNB. In such an embodiment, transceiver 725 receives an RRC layer suspension request from a remote unit (e.g., from a UE), and processor 705 maintains the UE AS context of the remote unit. Additionally, processor 705 may disable downlink transmissions to the remote unit in response to an RRC layer suspension request. In response to receiving an RRC layer connection resume request from the remote unit, processor 705 enables downlink transmissions to the remote unit (UE).

[0157] In certain embodiments, transceiver 725 transmits a suspension timer value associated with a short connection suspension of a second SIM, and processor 705 releases the UE AS context in response to the expiration of the suspension timer. For example, transceiver 625 may receive a suspension response message containing the suspension timer value. As another example, the suspension timer value may be broadcast in a system information block (“SIB”) or negotiated during a NAS registration procedure. In such an embodiment, transceiver 725 may further indicate to the remote unit the type of suspension state, where the remote unit transitions to the indicated suspension state in response to the expiration of the suspension timer. Here, the type of suspension state may be transmitted to the remote unit together with the suspension timer value.

[0158] In some embodiments, processor 705 buffers downlink packets of the remote unit in response to an RRC layer suspension request. Here, transceiver 725 may attempt to deliver the buffered downlink packets in response to receiving an RRC layer connection resume request from the remote unit. In certain embodiments, processor 705 suppresses the RAN paging process of the remote unit in response to receiving an RRC layer suspension request. In such an embodiment, processor 705 stops suppressing the RAN paging process of the remote unit in response to receiving an RRC layer connection resume request.

[0159] In some embodiments, the network device apparatus 700 may operate as a CN management function such as AMF 143, AMF-1 415, and MME, etc. In such embodiments, the processor 705 may control the transceiver 725 to exchange the preferred (or supported) M-USIM capabilities with the UE. This may include receiving an indication of whether the UE supports M-USIM features / enhancements or whether it supports only a single suspended state (e.g., a long suspended state at the NAS) or whether it supports multiple suspended states (e.g., a long suspended state at the NAS and a short suspended state at the AS). In various embodiments, the processor 705 controls the transceiver 725 to send a reply to the UE, the reply including a configuration (or preference) of whether to apply M-USIM features / enhancements, or which suspended mode to use (e.g., a single suspended state or multiple suspended states) or the short suspended duration (e.g., considered by the UE when determining whether to apply a short connection suspended state or a long connection suspended state). The processor 705 controlling the transceiver 725 may also send an indication (or configuration) message to the RAN node, e.g., gNB or eNB, regarding whether the short suspended state is allowed for the UE.

[0160] In one embodiment, the memory 710 is a computer-readable storage medium. In some embodiments, the memory 710 includes volatile computer storage media. For example, the memory 710 may include RAM, including dynamic RAM (“DRAM”), synchronous dynamic RAM (“SDRAM”), and / or static RAM (“SRAM”). In some embodiments, the memory 710 includes non-volatile computer storage media. For example, the memory 710 may include a hard disk drive, a flash memory, or any other suitable non-volatile computer storage device. In some embodiments, the memory 710 includes both volatile and non-volatile computer storage media. In some embodiments, the memory 710 stores data related to suspending the connection of one SIM during multi-SIM operation, such as storing UE AS context, UE state, etc. In certain embodiments, the memory 710 also stores program code and related data, such as an operating system (“OS”) operating on the network device apparatus 700 or other controller algorithms and one or more software applications.

[0161] In one embodiment, the input device 715 may include any known computer input device, including a touch panel, buttons, a keyboard, a stylus, a microphone, etc. In some embodiments, the input device 715 may be integrated with the output device 720, e.g., as a touch screen or a similar touch-sensitive display. In some embodiments, the input device 715 includes a touch screen such that text can be input using a virtual keyboard displayed on the touch screen and / or by handwriting on the touch screen. In some embodiments, the input device 715 includes two or more different devices, such as a keyboard and a touch panel.

[0162] In one embodiment, output device 720 may include any known electronically controllable display or display device. Output device 720 may be designed to output visual, auditory, and / or tactile signals. In some embodiments, output device 720 includes an electronic display capable of outputting visual data to a user. For example, output device 720 may include, but is not limited to, an LCD display, an LED display, an OLED display, a projector, or a similar display device capable of outputting images, text, etc. to a user. As another non-limiting example, output device 720 may include a wearable display, such as a smartwatch, smart glasses, a head-up display, etc. Additionally, output device 720 may be a component of a smartphone, a personal digital assistant, a television, a desktop computer, a notebook (laptop) computer, a personal computer, a vehicle dashboard, etc.

[0163] In certain embodiments, output device 720 includes one or more speakers for generating sound. For example, output device 720 may generate an audible alert or notification (e.g., a beep or a buzzer). In some embodiments, output device 720 includes one or more haptic devices for generating vibration, movement, or other haptic feedback. In some embodiments, all or part of output device 720 may be integrated with input device 715. For example, input device 715 and output device 720 may form a touchscreen or a similar touch-sensitive display. In other embodiments, all or part of output device 720 may be located near input device 715.

[0164] As described above, transceiver 725 may communicate with one or more remote units and / or with one or more interworking functions that provide access to one or more PLMNs. Transceiver 725 may also communicate with one or more network functions (e.g., in mobile core network 140). Transceiver 725 operates under the control of processor 705 to transmit messages, data, and other signals, and also to receive messages, data, and other signals. For example, processor 705 may selectively activate transceiver (or a portion thereof) at a particular time to send and receive messages.

[0165] Transceiver 725 may include one or more transmitters 730 and one or more receivers 735. In certain embodiments, one or more transmitters 730 and / or one or more receivers 735 may share transceiver hardware and / or circuitry. For example, one or more transmitters 730 and / or one or more receivers 735 may share an antenna, an antenna tuner, an amplifier, a filter, an oscillator, a mixer, a modulator / demodulator, a power supply, etc. In one embodiment, transceiver 725 implements multiple logical transceivers using different communication protocols or protocol stacks while using common physical hardware.

[0166] Figure 8 FIG. 800 depicts a method for pausing the connection of one SIM during multi-SIM operation in accordance with an embodiment of the present disclosure. In some embodiments, method 800 is performed by a device such as remote unit 105, multi-SIM UE 205, and / or user equipment device 600. In certain embodiments, method 800 may be performed by a processor that executes program code, such as a microcontroller, a microprocessor, a CPU, a GPU, an auxiliary processing unit, an FPGA, etc.

[0167] Method 800 begins and registers 805 a first SIM with a first mobile communication network. Method 800 includes registering 810 a second SIM with a second mobile communication network. Method 800 includes receiving 815 a communication trigger associated with the first SIM, the communication trigger indicating a service type. Method 800 includes determining 820 whether to apply a short connection pause or a long connection pause to the second SIM. Here, the determination is based on the service type. Method 800 includes applying 825 one of a short connection pause and a long connection pause to the second SIM. Method 800 ends.

[0168] Figure 9 FIG. 900 depicts a method for pausing the connection of one SIM during multi-SIM operation in accordance with an embodiment of the present disclosure. In some embodiments, method 900 is performed by a network device such as base station unit 121, (R)AN-1 node 410, network equipment device 700, gNB, eNB, and / or RAN node. In certain embodiments, method 900 may be performed by a processor that executes program code, such as a microcontroller, a microprocessor, a CPU, a GPU, an auxiliary processing unit, an FPGA, etc.

[0169] Method 900 begins and receives 905 an RRC layer pause request from a UE (e.g., remote unit 105). Method 900 includes maintaining 910 the UE AS context of the UE. Method 900 includes disabling 915 downlink transmission to the UE in response to the RRC layer pause request. Method 900 includes enabling 920 downlink transmission to the UE in response to receiving an RRC layer connection resume request from the UE. Method 900 ends.

[0170] According to an embodiment of the present disclosure, a first apparatus for pausing the connection of one SIM during multi-SIM operation is disclosed herein. The first apparatus may be implemented by a UE such as remote unit 105, multi-SIM UE 205, and / or user equipment apparatus 600. The first apparatus includes a processor, a first SIM registered with a first mobile communication network, a second SIM registered with a second mobile communication network, and a transceiver communicating with the first and second mobile communication networks. The processor receives a communication trigger associated with the first SIM, the communication trigger indicating a service type, and determines whether to apply a short connection pause or a long connection pause to the second SIM, the determination being based on the service type. The processor further applies one of the selected short connection pause and long connection pause to the second SIM.

[0171] In some embodiments, the application or service type associated with the first SIM is configured to have a higher priority than the application or service currently being used with the second SIM. In certain embodiments, if the second SIM is participating in an emergency communication session, the processor determines not to pause the connection of the second SIM.

[0172] In some embodiments, applying a short connection pause to the second SIM includes transmitting an RRC layer pause request, while applying a long connection pause to the second SIM includes transmitting an NAS layer pause request. In certain embodiments, applying a long connection pause to the second SIM further includes transitioning to the NAS idle state in response to receiving a pause response message from the second network, where the pause response message includes one or more of the following messages: an RRC layer message or an NAS layer message. Here, the pause response message is sent in response to the NAS layer pause request message.

[0173] In certain embodiments, applying a short connection pause further includes the processor disabling the transmission of the second SIM in response to receiving an RRC layer pause response. In certain embodiments, applying a short connection pause includes the processor maintaining the access stratum context of the second SIM.

[0174] In some embodiments, registering the first SIM and the second SIM includes indicating support for one or more of the following parameters: multi-SIM enhancement, short connection pause, or long connection pause, receiving a network preference indicating whether to apply multi-SIM enhancement, short connection pause, or long connection pause, and configuring the processor to apply multi-SIM enhancement, short connection pause, or long connection pause based on the received network preference. In certain embodiments, not receiving any network preference may be interpreted by the UE as an indication that multi-SIM enhancement is not supported in the network.

[0175] In various embodiments, the processor activates a connection associated with a first SIM, performs a communication corresponding to a communication trigger, and transmits release assistance information in response to ending the communication corresponding to the communication trigger, the release assistance information including one or more of access stratum release assistance information and non-access stratum release assistance information. In such an embodiment, in response to ending the communication corresponding to the communication trigger, the processor further resumes a suspended connection in a second communication network associated with a second SIM. In certain embodiments, resuming the suspended connection includes one or more of: transmitting an RRC layer connection resume request in response to transmitting an RRC layer suspend request; and transmitting a NAS layer resume request in response to transmitting a NAS layer suspend request.

[0176] In some embodiments, the transceiver also receives a suspend timer value associated with a short connection suspend of the second SIM, wherein the processor initiates a suspend timer in response to receiving an RRC layer suspend response, and transitions from a short connection suspend to a long connection suspend in response to the expiration of the suspend timer. In some embodiments, determining whether to apply a short connection suspend or a long connection suspend to the second SIM is further based on a bearer type associated with the second SIM, wherein the processor determines to apply a long connection suspend in response to the second SIM being associated with a guaranteed bit rate bearer.

[0177] According to an embodiment of the present disclosure, a first method for suspending a connection of one SIM during multi-SIM operation is disclosed herein. The first method may be performed by a UE such as remote unit 105, multi-SIM UE 205, and / or user equipment device 600. The first method includes registering a first SIM with a first mobile communication network and registering a second SIM with a second mobile communication network. The first method includes receiving a communication trigger associated with the first SIM, the communication trigger indicating a service type, and determining whether to apply a short connection suspend or a long connection suspend to the second SIM. Here, the determination is based on the service type. The first method includes applying one of a short connection suspend and a long connection suspend to the second SIM.

[0178] In some embodiments, applying a short connection suspend to the second SIM includes transmitting an RRC layer suspend request, and applying a long connection suspend to the second SIM includes transmitting a NAS layer suspend request. In certain embodiments, applying a long connection suspend to the second SIM further includes: transitioning to a NAS idle state in response to receiving a suspend response message from the second network. In such an embodiment, the suspend response message includes one or more of an RRC layer message and a NAS layer message. Here, the suspend response message is a response to a NAS layer suspend request message. In certain embodiments, applying a short connection suspend further includes disabling transmission of the second SIM in response to receiving an RRC layer suspend response. In certain embodiments, applying a short connection suspend includes maintaining an access stratum context of the second SIM.

[0179] In some embodiments, registering the first SIM and the second SIM includes indicating that the device supports one or more of the following parameters: multi-SIM enhancement, short connection suspension, or long connection suspension. In such embodiments, registering the first SIM and the second SIM further includes receiving a network preference that indicates whether to apply multi-SIM enhancement, short connection suspension, or long connection suspension, and configuring the device to apply multi-SIM enhancement, short connection suspension, or long connection suspension based on the received network preference.

[0180] In some embodiments, the first method includes receiving a suspension timer value associated with a short connection suspension of the second SIM, initiating the suspension timer in response to receiving an RRC layer suspension response, and transitioning from a short connection suspension to a long connection suspension in response to the expiration of the suspension timer.

[0181] In some embodiments, the first method includes activating a connection associated with the first SIM, performing a communication corresponding to a communication trigger, and sending release assistance information in response to ending the communication corresponding to the communication trigger, the release assistance information including one or more of access stratum release assistance information and non-access stratum release assistance information. In such embodiments, the first method may further include resuming a suspended connection in a second communication network associated with the second SIM in response to ending the communication corresponding to the communication trigger. In certain embodiments, resuming the suspended connection includes one or more of the following: sending an RRC layer connection resume request in response to transmitting an RRC layer suspension request; and sending an NAS layer resume request in response to transmitting an NAS layer suspension request.

[0182] In certain embodiments, the application or service type associated with the first SIM is configured to have a higher priority than the application or service currently being used with the second SIM. In some embodiments, the first method includes determining not to suspend the connection of the second SIM if the second SIM is participating in an emergency communication session.

[0183] In certain embodiments, determining whether to apply a short connection suspension or a long connection suspension to the second SIM is further based on the bearer type associated with the second SIM. In such embodiments, applying one of a short connection suspension and a long connection suspension to the second SIM includes applying a long connection suspension in response to the second SIM being associated with a guaranteed bit rate bearer.

[0184] According to an embodiment of the present disclosure, a second apparatus for pausing the connection of one SIM during multi-SIM operation is disclosed herein. The second apparatus may be implemented by a RAN node such as a base station unit 121, a (R)AN-1 node 410, and / or a network device apparatus 700. The second apparatus includes a processor and a transceiver that receives an RRC layer pause request from a remote unit. The processor maintains the UE AS context of the remote unit in response to the RRC layer pause request. The processor also disables the downlink transmission to the remote unit in response to the RRC layer pause request, and enables the downlink transmission to the remote unit in response to receiving an RRC layer connection resume request from the remote unit.

[0185] In some embodiments, the transceiver also transmits a pause timer value associated with the short connection pause of the second SIM, wherein the processor releases the UE AS context in response to the expiration of the pause timer. In such an embodiment, the transceiver may also indicate the type of pause state to the remote unit, wherein the remote unit transitions to the indicated pause state in response to the expiration of the pause timer.

[0186] In some embodiments, the processor also buffers the downlink packets of the remote unit in response to the RRC layer pause request, wherein the transceiver attempts to deliver the buffered downlink packets in response to receiving an RRC layer connection resume request from the remote unit. In certain embodiments, the processor also suppresses the RAN paging process of the remote unit in response to receiving the RRC layer pause request, and stops suppressing the RAN paging process of the remote unit in response to receiving the RRC layer connection resume request.

[0187] According to an embodiment of the present disclosure, a second method for pausing the connection of one SIM during multi-SIM operation is disclosed herein. The second method may be performed by a RAN node such as a base station unit 121, a (R)AN-1 node 410, and / or a network device apparatus 700. The second method includes receiving an RRC layer pause request from a remote unit and maintaining the UE AS context for the remote unit (e.g., in response to receiving the RRC layer pause request). The second method includes disabling the downlink transmission to the remote unit in response to the RRC layer pause request, and enabling the downlink transmission to the remote unit in response to receiving an RRC layer connection resume request from the remote unit.

[0188] In some embodiments, the second method includes transmitting a pause timer value associated with the short connection pause of the second SIM to the remote unit and releasing the UE AS context in response to the expiration of the pause timer. In certain embodiments, the second method also includes indicating the type of pause state to the remote unit, wherein the remote unit transitions to the indicated pause state in response to the expiration of the pause timer.

[0189] In some embodiments, the second method includes buffering downlink packets of a remote unit in response to an RRC layer suspension request and attempting to deliver the buffered downlink packets in response to receiving an RRC layer connection resume request from the remote unit. In some embodiments, the second method includes suppressing the RAN paging process of the remote unit in response to receiving an RRC layer suspension request and stopping suppressing the RAN paging process of the remote unit in response to receiving an RRC layer connection resume request.

[0190] Embodiments may be practiced in other specific forms. The described embodiments are to be considered in all respects only as illustrative and not restrictive. Thus, the scope of the invention is indicated by the appended claims rather than by the foregoing description. All changes which come within the meaning and range of equivalency of the claims are to be embraced within their scope.

Claims

1. A device, comprising: A first Subscriber Identity Module (SIM), the first SIM being registered with a first mobile communication network; A second SIM, the second SIM being registered with a second mobile communication network; A processor; And A memory coupled to the processor, the processor being configured to: Communicate with the second mobile communication network in a connected state; Detect an activity associated with the first SIM; And In response to the detected activity associated with the first SIM, send a connection release message from the connected state for the second SIM by sending one of a Radio Resource Control (RRC) layer request message indicating connection release and a Non-Access Stratum (NAS) layer request message indicating connection release; Initiate a state transition timer based on the transmission of the connection release request message; and Transition to an idle state in response to the expiration of the state transition timer without receiving a response message from the second mobile communication network.

2. The apparatus according to claim 1, wherein, The application or service type associated with the first SIM is configured to have a higher priority than the application or service currently used with the second SIM.

3. The device according to claim 1, wherein, The processor is configured to determine whether to apply an RRC connection release to the connection associated with the second SIM or an NAS connection release to the connection associated with the second SIM, the determination being based on the application or service type associated with the connection associated with the second SIM.

4. The device according to claim 3, wherein To apply the NAS connection release, the processor is configured to cause the device to: transition to the NAS idle state in response to receiving a release response message from the second mobile communication network, where the release response message includes: an RRC layer message or an NAS layer message or a combination thereof, the release response message being sent as a response to the NAS layer request message.

5. The device according to claim 3, wherein, To apply the RRC connection release, the processor is configured to cause the device to: disable transmission for the second SIM in response to receiving an RRC layer release response while remaining in the connected state.

6. The device according to claim 3, wherein, To apply the RRC connection release, the processor is configured to cause the device to: maintain the Access Stratum (AS) context of the second SIM.

7. The device according to claim 3, wherein, The processor is configured to cause the device to: Receive a state transition timer value associated with the RRC connection release of the second SIM; Initiate the state transition timer in response to the transmission of the connection release request message.

8. The apparatus according to claim 3, wherein, The processor is configured to cause the device to: Receive a transmission pause timer value associated with the RRC connection release of the second SIM; Disable data transmission while the transmission pause timer value is running.

9. The device according to claim 1, wherein The processor is configured to cause the device to: Indicate support for one or more of the following parameters: multi-SIM enhancement, RRC connection release, or NAS connection release; and Receive a network preference indicating whether to apply multi-SIM enhancement, or the RRC connection release, or the NAS connection release; Wherein, based on the received network preference, perform a connection release from the connected state of the second SIM.

10. The device according to claim 1, wherein, The processor is configured to cause the device to: Activate the connection associated with the first SIM; Perform communication corresponding to the communication trigger; And In response to ending the communication corresponding to the communication trigger, send release assistance information, where the release assistance information includes one or more of the following: access stratum AS release assistance information and NAS release assistance information.

11. The apparatus according to claim 10, wherein, The processor is configured to cause the device to: in response to ending the communication corresponding to the communication trigger, resume the released connection in the second mobile communication network associated with the second SIM.

12. The apparatus according to claim 11, wherein, For resuming the released connection, the processor is configured to cause the device to: in response to transmitting the RRC layer request message, send an RRC layer connection resume request; or in response to transmitting the NAS layer request message, send a NAS layer resume request.

13. The device according to claim 1, wherein, The processor is configured to: in response to the second SIM not participating in an emergency communication session, determine to release the connection state of the second SIM.

14. The apparatus according to claim 13, wherein, The processor is configured to: based on the bearer type associated with the second SIM, determine whether to apply an RRC connection release or a NAS connection release to the second SIM, where the processor determines to apply the NAS connection release in response to the second SIM being associated with a guaranteed bit rate bearer.

15. A method, comprising: Register a first subscriber identity module SIM with a first mobile communication network; Register a second SIM with a second mobile communication network; Communicate with the second mobile communication network in a connected state; Detect an activity associated with the first SIM; And In response to the detected activity associated with the first SIM, send a connection release message from the connected state for the second SIM by sending one of a radio resource control RRC layer request message indicating connection release and a non-access stratum NAS layer request message indicating connection release; Based on the sending of the connection release request message, initiate a state transition timer; and In response to the expiration of the state transition timer without receiving a response message from the second mobile communication network, transition to an idle state.

16. A device, comprising: A processor, the processor: A memory coupled to the processor, the processor being configured to: Receive a radio resource control RRC layer request message for connection release associated with a transmission pause time from a user equipment UE; And Send a connection release response including a timer value of a state transition timer; Maintain a user equipment access stratum UE AS context of the UE in a connected state; In response to the RRC layer request message, disable downlink transmission to the UE during the state transition timer; And In response to the expiration of the state transition timer, release the UE AS context.

17. The apparatus according to claim 16, wherein, The processor is configured to cause the device to: Transmit a second timer value of a pause timer associated with the connection release of the state transition timer, and In response to the expiration of the pause timer, release the UE AS context.

18. The apparatus according to claim 17, wherein, The processor is configured to cause the device to: indicate to the UE a type of a suspended state, wherein expiration of the suspension timer triggers a UE state transition to the indicated suspended state.

19. The apparatus according to claim 16, wherein, The processor is configured to cause the device to: buffer downlink packets of the UE in response to the RRC layer request message; initiate downlink transmission to the UE in response to receiving the RRC layer connection resume request from the UE; and attempt to deliver the buffered downlink packets in response to receiving the RRC layer connection resume request from the UE.

20. The apparatus according to claim 16, wherein, The processor is configured to cause the device to: suppress a radio access network RAN paging procedure of the UE in response to receiving the RRC layer request message, and stop suppressing the RAN paging procedure of the UE in response to receiving an RRC layer connection resume request.

21. A method, comprising: receiving, from a user equipment UE, an RRC layer request message for connection release associated with a transmission suspension time; sending a connection release response including a timer value of a state transition timer; maintaining a user equipment access stratum UE AS context of the UE in a connected state; disabling downlink transmission to the UE during the state transition timer in response to the radio resource control RRC layer request message; and releasing the UE AS context in response to expiration of the state transition timer.

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