User equipment, base station and method

Abstract

To provide a user device, base station and method that ensure quick switching of mobile networks by the user device without unnecessary signaling.SOLUTION: A user device 200 in a system comprises: an information acquisition section that acquires state transition information indicating an RRC state to which a user device transitions when switching from a first mobile network comprising a base station 100 and a network node 300 to a second mobile network comprising a base station 40 and a network node 50; and a communication processing section that transmits a UE Assistance Information message including the state transition information to the base station in the first mobile network in response to the registration of the user device in the second mobile network.SELECTED DRAWING: Figure 7

Description

[Technical field]

[0001] The present disclosure relates to a user equipment, a base station and a method. [Background technology]

[0002] In Release 17 of the 3GPP (3rd Generation Partnership Project), a work item has been launched to define a function for monitoring incoming information (e.g., voice or data) from multiple carrier networks for devices equipped with multiple SIM (Subscriber Identity Module) cards.

[0003] For example, according to Non-Patent Document 1, a technique is being considered in which, even when a User Equipment (UE) is in an RRC (Radio Resource Control) connected state in network A, the UE monitors paging in network B by setting a gap in communication in network A. This technique is called short-time switching.

[0004] Furthermore, according to Non-Patent Document 1, a technique is also being considered in which a UE notifies network A that it will temporarily leave network A when a high-priority incoming call is received in network B. This can reduce mismatches in the RRC states between network A and the UE. This technique is called long-time switching.

[0005] Furthermore, Non-Patent Document 2 describes that the RRC state to which the UE should transition at the time of detachment is pre-configured via RRC signaling for detachment notification without a network response. Also, Non-Patent Document 3 describes that at the time of suspension (i.e., detachment), information such as the cause of the suspension (i.e., detachment) and a preferred RRC state (e.g., RRC idle or RRC inactive) is transmitted to the network using a UE ASSISTANCE INFORMATION message. [Prior art documents] [Non-patent literature]

[0006] [Non-Patent Document 1] 3GPP TSG-RAN WG2 Meeting #113-e, Online, Jan 25th- Feb 05th 2021, R2-2100474, vivo, “[post112-e]

[0256] [Multi-SIM] Network switching details (vivo)” [Non-Patent Document 2] 3GPP TSG-RAN WG2 Meeting #113 Electronic, Elbonia, 25th of January - 5th of February 2021, R2-2100508, Nokia, Nokia Shanghai Bell, “Switching notification procedure for basic switching scenarios for Single RX UE” [Non-Patent Document 3] 3GPP TSG-RAN WG2 Meeting #113e, Electronic, 25-Jan-2021 to 05-Feb-2021, R2-2100850, Apple Inc, “Methods for MUSIM Network Switching” Summary of the Invention [Problem to be solved by the invention]

[0007] The inventor found a problem that, although Non-Patent Document 2 describes configuring in advance the RRC state to which the UE should transition when leaving, it does not show a specific method for reliably achieving this without unnecessary signaling. Furthermore, according to Non-Patent Document 3, the UE transmits information on the above-mentioned preferable RRC state to a network when switching networks, confirms reception of the information in the network, and then performs the above-mentioned switching, so that the inventor found a problem that it may take a long time to switch networks.

[0008] An object of the present disclosure is to provide a user equipment, a base station, and a method that enable a user equipment to reliably achieve rapid switching of a mobile network without unnecessary signaling. [Means for solving the problem]

[0009] A user equipment according to one embodiment of the present disclosure includes an information acquisition unit that acquires state transition information indicating an RRC state to which the user equipment transitions when switching from a first mobile network to a second mobile network, and a communication processing unit that transmits a UE Assistance Information message including the state transition information to a base station of the first mobile network in response to registration of the user equipment in the second mobile network.

[0010] A base station of a first mobile network according to one embodiment of the present disclosure includes: a communication processing unit that receives, from a user equipment, a UE Assistance Information message including state transition information indicating an RRC state to which a user equipment transitions upon switching from the first mobile network to a second mobile network, the UE Assistance Information message being transmitted by the user equipment in response to registration of the user equipment in the second mobile network; and an information acquisition unit that acquires the state transition information.

[0011] A method performed by a user equipment according to one embodiment of the present disclosure includes obtaining state transition information indicating an RRC state to which the user equipment transitions upon switching from a first mobile network to a second mobile network, and transmitting a UE Assistance Information message including the state transition information to a base station of the first mobile network in response to registration of the user equipment in the second mobile network.

[0012] A method performed by a base station of a first mobile network according to one embodiment of the present disclosure includes receiving, from a user equipment, a UE Assistance Information message including state transition information indicating an RRC state to which a user equipment transitions upon switching from the first mobile network to a second mobile network, the UE Assistance Information message being transmitted by the user equipment in response to registration of the user equipment in the second mobile network, and acquiring the state transition information. Effect of the Invention

[0013] According to the present disclosure, it is possible to reliably realize rapid switching of mobile networks by user equipment without unnecessary signaling. Note that the present disclosure may achieve other effects instead of or in addition to the above effect. [Brief description of the drawings]

[0014] [Figure 1] FIG. 1 is an explanatory diagram illustrating an example of a schematic configuration of a system according to an embodiment of the present disclosure. [Diagram 2] FIG. 1 is an explanatory diagram for explaining an example of a case in which a user equipment according to an embodiment of the present disclosure is equipped with two SIM cards. [Diagram 3] FIG. 2 is a block diagram illustrating an example of a schematic functional configuration of a base station according to an embodiment of the present disclosure. [Figure 4]FIG. 2 is a block diagram illustrating an example of a schematic hardware configuration of a base station according to an embodiment of the present disclosure. [Diagram 5] FIG. 2 is a block diagram illustrating an example of a schematic functional configuration of a user equipment according to an embodiment of the present disclosure. [Figure 6] FIG. 2 is a block diagram illustrating an example of a schematic hardware configuration of a user equipment according to an embodiment of the present disclosure. [Figure 7] FIG. 2 is a sequence diagram for explaining an example of a schematic flow of a process according to an embodiment of the present disclosure. [Figure 8] FIG. 11 is a sequence diagram for explaining an example of a schematic flow of a process according to a first modified example of an embodiment of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. In this specification and the drawings, elements that can be similarly described may be denoted by the same reference numerals, and repeated description may be omitted.

[0016] The explanation will be given in the following order: 1. System Configuration 2. Base Station Configuration 3. User device configuration 4. Example of operation 5. Variations

[0017] <1. System configuration> An example of the configuration of a system 1 according to an embodiment of the present disclosure will be described with reference to Fig. 1 and Fig. 2. Referring to Fig. 1, the system 1 includes a base station 100, a user equipment (UE) 200, and a core network 30. The core network 30 includes a network node 300.

[0018] For example, the system 1 is a system that complies with the Technical Specification (TS) of the Third Generation Partnership Project (3GPP). More specifically, for example, the system 1 is a system that complies with the TS of 5G or New Radio (NR). Of course, the system 1 is not limited to this example.

[0019] (1)Base station 100 The base station 100 is a node in a Radio Access Network (RAN) and communicates with UEs (eg, UE 200) located within a coverage area 10 of the base station 100.

[0020] For example, the base station 100 communicates with a UE (e.g., UE 200) using a protocol stack of the RAN. For example, the protocol stack includes Radio Resource Control (RRC), Service Data Adaptation Protocol (SDAP), Packet Data Convergence Protocol (PDCP), Radio Link Control (RLC), Medium Access Control (MAC), and a physical (PHY) layer protocol. Alternatively, the protocol stack may include only some of these protocols rather than all of them.

[0021] For example, the base station 100 is a gNB. The gNB is a node that provides NR user plane and control plane protocol terminations towards the UE and is connected to a 5G Core Network (5GC) via an NG interface. Alternatively, the base station 100 may be an en-gNB. The en-gNB is a node that provides NR user plane and control plane protocol terminations towards the UE and operates as a secondary node in E-UTRA-NR Dual Connectivity (EN-DC).

[0022] The base station 100 may include a plurality of nodes. The plurality of nodes may include a first node hosting a higher layer included in the protocol stack, and a second node hosting a lower layer included in the protocol stack. The higher layer may include RRC, SDAP, and PDCP, and the lower layer may include RLC, MAC, and a PHY layer. The first node may be a central unit (CU), and the second node may be a distributed unit (DU). The plurality of nodes may include a third node performing processing below the PHY layer, and the second node may perform processing above the PHY layer. The third node may be a radio unit (RU).

[0023] Alternatively, the base station 100 may be one of the plurality of nodes, and may be connected to other units of the plurality of nodes.

[0024] The base station 100 may be an Integrated Access and Backhaul (IAB) donor or an IAB node.

[0025] (2)UE200 The UE 200 communicates with a base station. For example, the UE 200 communicates with the base station 100 when the UE 200 is located within a coverage area 10 of the base station 100.

[0026] For example, the UE 200 communicates with a base station (eg, the base station 100) using the above protocol stack.

[0027] In particular, the UE 200 can be equipped with two or more SIM cards. That is, the UE 200 is a multi-SIM UE or a multi-SIM device. The UE 200 can communicate in two or more mobile networks corresponding to the two or more SIM cards, respectively. The mobile networks may simply be referred to as networks.

[0028] For example, the UE 200 can communicate in a mobile network (hereinafter referred to as a "first mobile network") corresponding to one of the two or more SIM cards and including the base station 100 and the network node 300. Furthermore, the UE 200 can communicate in a mobile network (hereinafter referred to as a "second mobile network") corresponding to another one of the two or more SIM cards.

[0029] 2, for example, UE 200 can communicate in a first mobile network including base station 100 and network node 300, and in a second mobile network including base station 40 and network node 50. As an example, UE 200 can be in an RRC connected state in the first mobile network and in an RRC idle state or an RRC inactive state in the second mobile network. In such a case, for example, UE 200 can receive a paging message transmitted by base station 40 in the second mobile network while communicating with base station 100 in the first mobile network.

[0030] (3) Network node 300 The network node 300 is a network function of the core network 30. For example, the network node 300 is an Access and Mobility Management Function (AMF).

[0031] <2. Base station configuration> An example of the configuration of the base station 100 according to the embodiment of the present disclosure will be described with reference to FIGS.

[0032] (1) Functional configuration First, an example of a functional configuration of a base station 100 according to an embodiment of the present disclosure will be described with reference to Fig. 3. Referring to Fig. 3, the base station 100 includes a wireless communication unit 110, a network communication unit 120, a storage unit 130, and a processing unit 140.

[0033] The wireless communication unit 110 transmits and receives signals wirelessly. For example, the wireless communication unit 110 receives signals from a UE and transmits signals to the UE.

[0034] The network communication unit 120 receives signals from a network and transmits signals to a network.

[0035] The storage unit 130 stores various information.

[0036] The processing unit 140 provides various functions of the base station 100. The processing unit 140 includes an information acquisition unit 141, a communication processing unit 143, and a control unit 145. The processing unit 140 may further include other components in addition to these components. That is, the processing unit 140 may also perform operations other than the operations of these components. The specific operations of the information acquisition unit 141, the communication processing unit 143, and the control unit 145 will be described in detail later.

[0037] For example, the processing unit 140 (communication processing unit 143) communicates with a UE (for example, the UE 200) via the wireless communication unit 110. For example, the processing unit 140 communicates with another node (for example, the network node 300 or another base station in the core network 30) via the network communication unit 120.

[0038] (2) Hardware Configuration Next, an example of a hardware configuration of the base station 100 according to an embodiment of the present disclosure will be described with reference to Fig. 4. Referring to Fig. 4, the base station 100 includes an antenna 181, an RF circuit 183, a network interface 185, a processor 187, a memory 189, and a storage 191.

[0039] The antenna 181 converts a signal into a radio wave and radiates the radio wave into space. The antenna 181 also receives radio waves in space and converts the radio waves into a signal. The antenna 181 may include a transmitting antenna and a receiving antenna, or may be a single antenna for transmitting and receiving. The antenna 181 may be a directional antenna and may include multiple antenna elements.

[0040] The RF circuit 183 performs analog processing of signals transmitted and received via the antenna 181. The RF circuit 183 may include a high-frequency filter, an amplifier, a modulator, a low-pass filter, and the like.

[0041] The network interface 185 is, for example, a network adapter, and transmits signals to and receives signals from the network.

[0042] The processor 187 performs digital processing of signals transmitted and received via the antenna 181 and the RF circuitry 183. The digital processing includes processing of a protocol stack of the RAN. The processor 187 also processes signals transmitted and received via the network interface 185. The processor 187 may include multiple processors or may be a single processor. The multiple processors may include a baseband processor that performs the digital processing and one or more processors that perform other processing.

[0043] Memory 189 stores programs executed by processor 187, parameters related to the programs, and various other information. Memory 189 may include at least one of a read only memory (ROM), an erasable programmable read only memory (EPROM), an electrically erasable programmable read only memory (EEPROM), a random access memory (RAM), and a flash memory. All or a part of memory 189 may be included in processor 187.

[0044] The storage 191 stores various information. The storage 191 may include at least one of a solid state drive (SSD) and a hard disc drive (HDD).

[0045] The wireless communication unit 110 may be implemented by an antenna 181 and an RF circuit 183. The network communication unit 120 may be implemented by a network interface 185. The memory unit 130 may be implemented by a storage 191. The processing unit 140 may be implemented by a processor 187 and a memory 189.

[0046] A part or all of the processing unit 140 may be virtualized. In other words, a part or all of the processing unit 140 may be implemented as a virtual machine. In this case, a part or all of the processing unit 140 may operate as a virtual machine on a physical machine (i.e., hardware) including a processor, a memory, and the like, and on a hypervisor.

[0047] Considering the above hardware configuration, base station 100 may include a memory (i.e., memory 189) that stores a program, and one or more processors (i.e., processor 187) that can execute the program, and the one or more processors may execute the program to perform the operation of processing unit 140. The program may be a program for causing a processor to execute the operation of processing unit 140.

[0048] <3. User device configuration> An example of the configuration of the UE 200 according to the embodiment of the present disclosure will be described with reference to FIGS.

[0049] (1) Functional configuration First, an example of a functional configuration of the UE 200 according to the embodiment of the present disclosure will be described with reference to Fig. 5. Referring to Fig. 5, the UE 200 includes a wireless communication unit 210, a storage unit 220, and a processing unit 230.

[0050] The wireless communication unit 210 transmits and receives signals wirelessly. For example, the wireless communication unit 210 receives a signal from a base station and transmits the signal to the base station. For example, the wireless communication unit 210 receives a signal from another UE and transmits the signal to the other UE.

[0051] The storage unit 220 stores various information.

[0052] The processing unit 230 provides various functions of the UE 200. The processing unit 230 includes an information acquisition unit 231, a communication processing unit 233, and a control unit 235. The processing unit 230 may further include other components in addition to these components. That is, the processing unit 230 may also perform operations other than the operations of these components. Specific operations of the information acquisition unit 231, the communication processing unit 233, and the control unit 235 will be described in detail later.

[0053] For example, the processing unit 230 (communication processing unit 233) communicates with a base station (for example, the base station 100 or the base station 40) or other UE via the wireless communication unit 210.

[0054] (2) Hardware Configuration Next, an example of a hardware configuration of the UE 200 according to an embodiment of the present disclosure will be described with reference to Fig. 6. Referring to Fig. 6, the UE 200 includes an antenna 281, an RF circuit 283, a processor 285, a memory 287, and a storage 289.

[0055] Antenna 281 converts signals into radio waves and radiates the radio waves into space. Antenna 281 also receives radio waves in space and converts the radio waves into signals. Antenna 281 may include a transmitting antenna and a receiving antenna, or may be a single antenna for transmitting and receiving. Antenna 281 may be a directional antenna and may include multiple antenna elements.

[0056] The RF circuit 283 performs analog processing of signals transmitted and received via the antenna 281. The RF circuit 283 may include a high-frequency filter, an amplifier, a modulator, a low-pass filter, and the like.

[0057] The processor 285 performs digital processing of signals transmitted and received via the antenna 281 and the RF circuitry 283. The digital processing includes processing of a protocol stack of the RAN. The processor 285 may include multiple processors or may be a single processor. The multiple processors may include a baseband processor that performs the digital processing and one or more processors that perform other processing.

[0058] The memory 287 stores programs executed by the processor 285, parameters related to the programs, and various other information. The memory 287 may include at least one of a ROM, an EPROM, an EEPROM, a RAM, and a flash memory. All or a part of the memory 287 may be included within the processor 285.

[0059] The storage 289 stores various information and may include at least one of an SSD and an HDD.

[0060] The wireless communication unit 210 may be implemented by an antenna 281 and an RF circuit 283. The memory unit 220 may be implemented by a storage 289. The processing unit 230 may be implemented by a processor 285 and a memory 287.

[0061] The processing unit 230 may be implemented by a system on chip (SoC) including a processor 285 and a memory 287. The SoC may include an RF circuit 283, and the wireless communication unit 210 may also be implemented by the SoC.

[0062] Considering the above hardware configuration, UE 200 may include a memory (i.e., memory 287) that stores a program, and one or more processors (i.e., processor 285) that can execute the program, and the one or more processors may execute the program to perform the operation of processing unit 230. The program may be a program for causing the processor to execute the operation of processing unit 230.

[0063] <4. Example of operation> An example of the operation of the base station 100 and the UE 200 according to the embodiment of the present disclosure will be described with reference to FIG.

[0064] (1) Sending and receiving state transition information The UE 200 (information acquisition unit 231) acquires state transition information indicating an RRC state to which the UE 200 transitions when switching from a first mobile network to a second mobile network. The UE 200 (communication processing unit 233) transmits a UE Assistance Information message including the state transition information to the base station 100 of the first mobile network in response to registration of the UE 200 in the second mobile network.

[0065] The base station 100 (communication processing unit 143) receives the UE Assistance Information message including the state transition information from the UE 200. The base station 100 (information acquisition unit 141) acquires the state transition information.

[0066] The RRC state indicated by the state transition information is set in each of the base station 100 and the UE 200 as the RRC state of the UE 200 after the switching.

[0067] -RRC state The RRC state is an RRC idle state or an RRC inactive state.

[0068] As described above, the RRC state is an RRC state to which the UE 200 transitions at the time of the switching. Since the UE 200 autonomously releases the RRC connection at the time of the switching, the RRC state can also be said to be an RRC state to which the UE 200 transitions in response to the autonomous release of the RRC connection by the UE 200.

[0069] - Configuring the transmission of state transition information For example, the base station 100 (information acquisition unit 141) acquires configuration information for configuring the UE 200 to transmit the above-mentioned state transition information. The base station 100 (communication processing unit 143) transmits an RRC Reconfiguration message including the above-mentioned configuration information to the UE 200. For example, since the UE 200 has multi-SIM capability, the base station 100 transmits the above-mentioned configuration information to the UE 200.

[0070] For example, the UE 200 (communication processing unit 233) receives the RRC Reconfiguration message including the configuration information from the base station 100. The UE 200 (information acquisition unit 231) acquires the configuration information. For example, the UE 200 (communication processing unit 233) transmits the state transition information to the base station 100 on the condition that the UE 200 receives the configuration information.

[0071] -Transmission timing As described above, in response to the registration of the UE 200 in the second mobile network, the UE 200 (the communication processing unit 233) transmits the UE Assistance Information message including the state transition information to the base station 100. More specifically, the UE 200 (the communication processing unit 233) transmits the UE Assistance Information message to the base station 100 in response to the completion of the registration.

[0072] For example, the UE 200 (the communication processing unit 233) performs the registration when attaching to the second mobile network or when registering the location in the second mobile network.

[0073] For example, the UE 200 (communication processing unit 233) transmits a REGISTRATION REQUEST message to the network node 50 via the base station 40 as a procedure for the registration in the second mobile network, and receives a REGISTRATION ACCEPT message from the network node 50 via the base station 40. The REGISTRATION REQUEST message and the REGISTRATION ACCEPT message are NAS (Non-Access Stratum) messages.

[0074] As described above, the state transition information is transmitted and received. This allows, for example, the UE 200 to reliably achieve rapid switching to the second mobile network without unnecessary signaling. More specifically, since the state transition information is required in the base station 100 after the registration in the second mobile network, the state transition information is transmitted only when it is required. That is, since the state transition information is not transmitted unnecessarily, unauthorized signaling is avoided. Furthermore, since the state transition information is transmitted to the base station 100 in response to the registration in the second mobile network, the base station 100 can obtain the state transition information before paging to the UE 200 in the second mobile network occurs. Therefore, the UE 200 can reliably perform rapid switching to the second mobile network. Furthermore, the UE 200 can independently transmit the state transition information to the base station 100 in response to the registration in the second mobile network by using a UE ASSISTANCE INFORMATION message.

[0075] (2) Network switching For example, the UE 200 (the communication processing unit 233) transmits a message for notifying the switching to the first mobile network.

[0076] -message For example, the message is an RRC message for notifying the switching. In this case, the UE 200 (communication processing unit 233) transmits the message to the base station 100. The base station 100 (communication processing unit 143) receives the message from the UE 200.

[0077] -RRC state transitions For example, the UE 200 (communication processing unit 233) transitions the UE 200 to the RRC state (for example, RRC idle or RRC inactive) in response to reception of an acknowledgement (ACK) corresponding to the message for notifying the switching. For example, the ACK may be an ACK of the RLC layer, which is a protocol of layer 2, or an ACK of a hybrid automatic repeat request (HARQ) of the MAC layer, which is a protocol of layer 2. This allows, for example, at least confirmation of reception of the message, and allows for rapid switching.

[0078] Meanwhile, for example, in response to receiving the message, the base station 100 (communication processing unit 143) transitions the UE 200 to the RRC state in the base station 100. That is, the RRC state of the UE 200 maintained in the base station 100 becomes the RRC state indicated by the state transition information.

[0079] By such switching, the UE 200 can perform communication in the second mobile network even if the UE 200 is in an RRC connected state in the first mobile network. Also, by the state transition information, it is possible to suppress a mismatch in the RRC state between the first network (particularly the base station 100) and the UE 200.

[0080] (3) Processing flow With reference to FIG. 7, an example of a process according to an embodiment of the present disclosure will be described.

[0081] An RRC Reconfiguration procedure is performed between the UE 200 and the base station 100 (S401). For example, the base station 100 transmits to the UE 200 an RRC Reconfiguration message including configuration information for configuring the UE 200 to transmit state transition information.

[0082] The UE 200 performs a procedure for registration in the second mobile network (S403).

[0083] In response to the registration, the UE 200 transmits to the base station 100 a UE Assistance Information message including state transition information indicating an RRC state to which the UE 200 transitions when switching from the first mobile network to the second mobile network (S405). The base station 100 receives the UE Assistance Information message and acquires the state transition information. The UE 200 and the base station 100 set the RRC state as the RRC state of the UE 200 after the network switching (S407). For example, the RRC state is RRC inactive.

[0084] The UE 200 receives a paging message from the base station 40 (S409). The paging message includes identification information of the UE 200 and corresponding priority information. For example, the information indicates a high priority. The UE 200 determines to switch from the first mobile network to the second mobile network (S411). For example, the UE 200 determines to perform the switch.

[0085] The UE 200 transmits a message for notifying the switching to the base station 100 (S413). For example, the message is an RRC message for long-term switching. The UE 200 receives an ACK (for example, an RLC ACK or an HARQ ACK) corresponding to the message (S415), and transitions to the RRC state (for example, RRC inactive) (S417).

[0086] The UE 200 transmits a paging response to the base station 40 (S419). After that, the UE 200 starts communication in the second mobile network (S421).

[0087] In response to receiving the message from the UE 200 (S413), the base station 100 notifies the network node 300 of the switching (S423), and the network node 300 stops transmitting and receiving data to and from the UE 200 (S425). The base station 100 transmits a response to the message to the UE 200 (S427), and causes the base station 100 to transition the UE 200 to an RRC inactive state (S429).

[0088] In particular, the process of steps S417 to S421 and the process of steps S423 to S429 may be performed in parallel.

[0089] <5. Modifications> First to fourth modified examples according to the embodiment of the present disclosure will be described with reference to Fig. 8. Note that two or more of these modified examples may be combined.

[0090] (1) First Modification In the above-described example of the embodiment of the present disclosure, the UE 200 (the communication processing unit 233) transmits a message for notifying the switching from the first mobile network to the second mobile network to the first mobile network. The message is an RRC message for notifying the switching. However, the message according to the embodiment of the present disclosure is not limited to this example.

[0091] In a first modified example of the embodiment of the present disclosure, the message may be a NAS message for notifying the switching. In this case, the UE 200 (the communication processing unit 233) may transmit the message to the network node 300 in the core network 30 of the first mobile network.

[0092] -Processing flow An example of processing according to a first modified example of the embodiment of the present disclosure will be described with reference to Fig. 8. Note that only differences between the example of Fig. 8 and the example of Fig. 7 will be described here, and overlapping descriptions will be omitted.

[0093] The UE 200 transmits a message for notifying the switching to the network node 300 via the base station 100 (S513). For example, the message is a NAS message for long-term switching.

[0094] In response to receiving the message from the UE 200 (S513), the network node 300 stops transmitting and receiving data to and from the UE 200 (S523) and transmits a response to the message to the UE 200 (S525). Furthermore, the network node 300 notifies the base station 100 of the switchover (S527).

[0095] The base station 100 transmits an RRC Release message to the UE 200 (S529), and causes the UE 200 to transition to an RRC inactive state in the base station 100 (S531).

[0096] In particular, the process of steps S417 to S421 and the process of steps S523 to S531 may be performed in parallel.

[0097] (2) Second modified example In the above-described example of the embodiment of the present disclosure, the UE 200 (the communication processing unit 233) transmits the UE Assistance Information message including the state transition information to the base station 100 in response to the registration of the UE 200 in the second mobile network. However, the transmission of the state transition information according to the embodiment of the present disclosure is not limited to only this example.

[0098] In a second modified example of the embodiment of the present disclosure, the base station 100 (the communication processing unit 143) may transmit trigger information indicating at least one of a plurality of triggers for transmitting the UE Assistance Information message to the UE 200. As an example, the base station 100 (the communication processing unit 143) may transmit an RRC Reconfiguration message including the trigger information to the UE 200.

[0099] The UE 200 (the communication processing unit 233) may receive the trigger information from the base station 100. As an example, the UE 200 (the communication processing unit 233) may receive an RRC Reconfiguration message including the trigger information from the base station 100. The UE 200 (the communication processing unit 233) may transmit the UE Assistance Information message to the base station 100 in response to at least one trigger indicated by the trigger information.

[0100] The multiple triggers may include the registration of the UE 200 in the second mobile network.

[0101] This enables the UE 200 to transmit the state transition information to the base station 100, for example, also in response to a trigger other than the registration in the second mobile network.

[0102] (3) Third modified example In the above-described example of the embodiment of the present disclosure, when switching from the first mobile network to the second mobile network, the UE 200 transitions to the RRC state indicated by the state transition information. However, the transition according to the embodiment of the present disclosure is not limited to this example.

[0103] In a third variant of the embodiment of the present disclosure, a UE 2 If the UE 00 does not transmit the state transition information to the base station 100, 2 00 may transition to RRC idle upon the switching, which allows for a quick switching to the second network, for example, even if the state transition information is not transmitted.

[0104] (4) Fourth modified example In the above-described example of the embodiment of the present disclosure, the system 1 is a system that complies with 5G or NR TS. However, the system 1 according to the embodiment of the present disclosure is not limited to this example.

[0105] In a fourth variant of the embodiment of the present disclosure, the system 1 may be a system compliant with other TS of 3GPP. As an example, the system 1 may be a system compliant with TS of LTE (Long Term Evolution), LTE-A (LTE Advanced), or 4G, and the base station 100 may be an evolved Node B (eNB). Alternatively, the base station 100 may be an ng-eNB. As another example, the system 1 may be a system compliant with TS of 3G, and the base station 100 may be a Node B. As yet another example, the system 1 may be a system compliant with TS of next generation (e.g., 6G).

[0106] Alternatively, the system 1 may be a system conforming to a TS of another standardization organization for mobile communications.

[0107] Although the embodiment of the present disclosure has been described above, the present disclosure is not limited to the embodiment. It will be understood by those skilled in the art that the embodiment is merely an example, and that various modifications are possible without departing from the scope and spirit of the present disclosure.

[0108] For example, the steps in the processes described herein do not necessarily have to be performed chronologically according to the order depicted in the flowcharts or sequence diagrams. For example, the steps in the processes may be performed in an order different from that depicted in the flowcharts or sequence diagrams, or may be performed in parallel. Also, some of the steps in the processes may be deleted, and additional steps may be added to the processes.

[0109] For example, a method including the operation of one or more components of the apparatus described in this specification may be provided, or a program for causing a computer to execute the operation of the components may be provided. Also, a non-transitory tangible computer-readable storage medium having the program recorded thereon may be provided. Naturally, such methods, programs, and non-transitory tangible computer-readable storage mediums are also included in the present disclosure.

[0110] For example, in this disclosure, user equipment (UE) may be referred to by other names such as a mobile station, mobile terminal, mobile device, mobile unit, subscriber station, subscriber terminal, subscriber device, subscriber unit, wireless station, wireless terminal, wireless device, wireless unit, remote station, remote terminal, remote device, or remote unit.

[0111] For example, in the present disclosure, "transmit" may mean performing processing of at least one layer in a protocol stack used for transmission, or may mean physically transmitting a signal wirelessly or wired. Alternatively, "transmit" may mean a combination of performing processing of at least one layer and physically transmitting a signal wirelessly or wired. Similarly, "receive" may mean performing processing of at least one layer in a protocol stack used for reception, or may mean physically receiving a signal wirelessly or wired. Alternatively, "receive" may mean a combination of performing processing of at least one layer and physically receiving a signal wirelessly or wired. The at least one layer may be rephrased as at least one protocol.

[0112] For example, in this disclosure, "obtain / acquire" may mean obtaining information from stored information, obtaining information from information received from other nodes, or obtaining information by generating the information.

[0113] For example, in this disclosure, "include" and "comprise" do not mean including only the items listed, but may include only the items listed, or may include additional items in addition to the items listed.

[0114] For example, in this disclosure, "or" does not mean an exclusive or, but rather a logical or.

[0115] The technical features included in the above-described embodiment may be expressed as the following features. Of course, the present disclosure is not limited to the following features.

[0116] (Feature 1) A user device (200), an information acquisition unit (231) that acquires state transition information indicating an RRC (Radio Resource Control) state to which the user equipment transitions when switching from a first mobile network to a second mobile network; a communication processing unit (233) for transmitting a UE Assistance Information message including the state transition information to a base station (100) of the first mobile network in response to registration of the user equipment in the second mobile network; A user equipment comprising:

[0117] (Feature 2) 2. The user equipment according to feature 1, wherein the RRC state is an RRC idle state or an RRC inactive state.

[0118] (Feature 3) The user equipment according to feature 1 or 2, wherein the communication processing unit receives an RRC Reconfiguration message from the base station, the RRC Reconfiguration message including configuration information for configuring the user equipment to transmit the state transition information.

[0119] (Feature 4) 4. The user equipment according to any one of features 1 to 3, wherein the communication processing unit transmits a message for notifying the switching to the first mobile network.

[0120] (Feature 5) The message is an RRC message for notifying the switching, The communication processing unit transmits the message to the base station. 5. The user equipment according to feature 4.

[0121] (Feature 6) The message is a Non-Access Stratum (NAS) message for notifying the switching, The communication processing unit transmits the message to a network node (300) in a core network (30) of the first mobile network. 5. The user equipment according to feature 4.

[0122] (Feature 7) The user equipment according to any one of features 4 to 6, further comprising: a control unit (235) configured to transition the user equipment to the RRC state in response to reception of an acknowledgement (Acknowledge) corresponding to the message for notifying of the switching.

[0123] (Feature 8) The communication processing unit receives trigger information indicating at least one of a plurality of triggers for transmitting the UE Assistance Information message from the base station; The communication processing unit transmits the UE Assistance Information message to the base station in response to at least one trigger indicated by the trigger information; the plurality of triggers include the registration of the user equipment in the second mobile network. The user device according to any one of features 1 to 7.

[0124] (Feature 9) The user equipment can be equipped with two or more SIM (Subscriber Identity Module) cards, the first mobile network corresponds to one of the two or more SIM cards; the second mobile network corresponds to another one of the two or more SIM cards; The user device according to any one of features 1 to 8.

[0125] (Feature 10) A base station (100) of a first mobile network, a communication processing unit (143) for receiving, from the user equipment, a UE Assistance Information message including state transition information indicating an RRC (Radio Resource Control) state to which the user equipment (200) transitions when switching from the first mobile network to a second mobile network, the UE Assistance Information message being transmitted by the user equipment in response to registration of the user equipment in the second mobile network; An information acquisition unit (141) that acquires the state transition information; A base station comprising:

[0126] (Feature 11) 11. The base station according to feature 10, wherein the communication processing unit transmits an RRC Reconfiguration message to the user equipment, the RRC Reconfiguration message including configuration information for configuring the user equipment to transmit the state transition information.

[0127] (Feature 12) The communication processing unit receives a message for notifying the switching from the user equipment, A control unit (145) for transitioning the user equipment to the RRC state in the base station in response to receiving the message for notifying the switching, 12. The base station according to feature 10 or 11.

[0128] (Feature 13) The communication processing unit transmits, to the user equipment, trigger information indicating at least one of a plurality of triggers for transmitting the UE Assistance Information message; the plurality of triggers include the registration of the user equipment in the second mobile network. The base station according to any one of features 10 to 12.

[0129] (Feature 14) A method performed by a user equipment (200), comprising: acquiring state transition information indicating a Radio Resource Control (RRC) state to which the user equipment transitions when switching from a first mobile network to a second mobile network; transmitting a UE Assistance Information message including the state transition information to a base station (100) of the first mobile network in response to registration of the user equipment in the second mobile network; The method includes:

[0130] (Feature 15) A method performed by a base station (100) of a first mobile network, comprising: receiving, from the user equipment, a UE Assistance Information message including state transition information indicating an RRC (Radio Resource Control) state to which the user equipment (200) transitions when switching from the first mobile network to a second mobile network, the UE Assistance Information message being transmitted by the user equipment in response to registration of the user equipment in the second mobile network; acquiring the state transition information; The method includes:

[0131] (Feature 16) Obtaining state transition information indicating an RRC (Radio Resource Control) state to which a user equipment (200) transitions when switching from a first mobile network to a second mobile network; transmitting a UE Assistance Information message including the state transition information to a base station (100) of the first mobile network in response to registration of the user equipment in the second mobile network; A program that causes a computer to execute the following.

[0132] (Feature 17) receiving, from the user equipment, a UE Assistance Information message including state transition information indicating an RRC (Radio Resource Control) state to which the user equipment (200) transitions when switching from a first mobile network to a second mobile network, the UE Assistance Information message being transmitted by the user equipment in response to registration of the user equipment in the second mobile network; acquiring the state transition information; A program that causes a computer to execute the following.

[0133] (Feature 18) Obtaining state transition information indicating an RRC (Radio Resource Control) state to which a user equipment (200) transitions when switching from a first mobile network to a second mobile network; transmitting a UE Assistance Information message including the state transition information to a base station (100) of the first mobile network in response to registration of the user equipment in the second mobile network; A non-transitory tangible recording medium readable by a computer on which a program for causing a computer to execute the above is recorded.

[0134] (Feature 19) receiving, from the user equipment, a UE Assistance Information message including state transition information indicating an RRC (Radio Resource Control) state to which the user equipment (200) transitions when switching from a first mobile network to a second mobile network, the UE Assistance Information message being transmitted by the user equipment in response to registration of the user equipment in the second mobile network; acquiring the state transition information; A non-transitory tangible recording medium readable by a computer on which a program for causing a computer to execute the above is recorded. [Explanation of symbols]

[0135] 1 System 10. Coverage Area 30 Core Network 40 base station 50 network nodes 100 base stations 141 Information Acquisition Department 143 Communication processing unit 145 Control Unit 200 User Devices 231 Information Acquisition Department 233 Communication Processing Unit 235 Control Unit 300 network nodes

Claims

1. An apparatus (200), comprising: a communication processing unit (233) for receiving from a first network an RRC Reconfiguration message including first information for configuring the device to transmit a UE Assistance Information message including second information used to indicate an RRC state of the device, the RRC state being an RRC idle state or an RRC inactive state; Equipped with The communication processing unit transmits the UE Assistance Information message including the second information to the first network based on the first information before switching from the first network to the second network in an RRC connected state in the first network. Device.

2. The device of claim 1 , wherein the device has a capability to accommodate two or more Subscriber Identity Modules (SIMs).

3. the first network is a network corresponding to one of two or more SIMs of the device; the second network is a network corresponding to another of the two or more SIMs of the device; 3. The apparatus of claim 2.

4. A base station (100) in a first network, a communication processing unit (143) for transmitting to the device an RRC Reconfiguration message including first information for configuring the device to transmit a UE Assistance Information message including second information used to indicate an RRC state of the device, the RRC state being an RRC idle state or an RRC inactive state; Equipped with The communication processing unit receives from the device the UE Assistance Information message, the UE Assistance Information message including the second information, the UE Assistance Information message being transmitted based on the first information before switching from the first network to the second network in an RRC connected state in the first network. Base station.

5. The base station of claim 4 , wherein the device has a capability to accommodate more than one Subscriber Identity Module (SIM).

6. the first network is a network corresponding to one of two or more SIMs of the device; the second network is a network corresponding to another of the two or more SIMs of the device; The base station according to claim 5.

7. A method performed by an apparatus (200), comprising: receiving from a first network a Radio Resource Control (RRC) Reconfiguration message including first information for configuring the device to transmit a UE Assistance Information message including second information used to indicate a Radio Resource Control (RRC) state of the device, the RRC state being an RRC idle state or an RRC inactive state; sending, to the first network, a UE Assistance Information message including the second information based on the first information, before switching from the first network to a second network in an RRC connected state in the first network; The method includes:

8. The method of claim 7 , wherein the device has a capability to accommodate more than one Subscriber Identity Module (SIM).

9. the first network is a network corresponding to one of two or more SIMs of the device; the second network is a network corresponding to another of the two or more SIMs of the device; The method according to claim 8.

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