Terminal device and communication system

Abstract

To provide a technology that enables rapid network connections.SOLUTION: A communication system includes a communication terminal and a plurality of networks configured to be capable of wireless communication with the communication terminal. The communication terminal determines whether there is a collision among a plurality of paging messages respectively transmitted from the plurality of networks to the communication terminal (ST1615). When the communication terminal detects a paging collision, the communication terminal notifies at least one of the networks transmitting the paging messages causing the collision of the paging (ST1629).SELECTED DRAWING: Figure 16

Description

Technical Field

[0001] This disclosure relates to wireless communication technology.

Background Art

[0002] In 3GPP (3rd Generation Partnership Project), which is a standardization organization for mobile communication systems, the radio section is called Long Term Evolution (LTE), and for the overall system configuration including the core network and the radio access network (hereinafter collectively referred to as the network), a communication method called System Architecture Evolution (SAE) is being studied (for example, Non-Patent Documents 1 to 5). This communication method is also called the 3.9G (3.9 Generation) system.

[0003] As the access method of LTE, OFDM (Orthogonal Frequency Division Multiplexing) is used in the downlink direction, and SC-FDMA (Single Carrier Frequency Division Multiple Access) is used in the uplink direction. Also, different from W-CDMA (Wideband Code Division Multiple Access), LTE does not include circuit switching and is only a packet communication method.

[0004] Regarding the decisions on the frame configuration in the LTE system in 3GPP described in Non-Patent Document 1 (Chapter 5), it will be described with reference to FIG. 1. FIG. 1 is an explanatory diagram showing the configuration of a radio frame used in a communication system of the LTE method. In FIG. 1, one radio frame is 10 ms. The radio frame is divided into 10 subframes of equal size. The subframe is divided into 2 slots of equal size. The downlink synchronization signal is included in the first and sixth subframes for each radio frame. The synchronization signal includes a primary synchronization signal (P-SS) and a secondary synchronization signal (S-SS).

[0005] The decisions on the channel configuration in the LTE system in 3GPP are described in Non-Patent Document 1 (Chapter 5). It is assumed that the same channel configuration as that of a non-CSG cell is used even in a CSG (Closed Subscriber Group) cell.

[0006] The physical broadcast channel (PBCH) is a channel for downlink transmission from a base station device (hereinafter sometimes simply referred to as "base station") to a communication terminal device such as a mobile terminal device (hereinafter sometimes simply referred to as "mobile terminal") (hereinafter sometimes simply referred to as "communication terminal"). The BCH transport block is mapped to 4 subframes at 40 ms intervals. There is no explicit signaling at 40 ms timing.

[0007] The Physical Control Format Indicator Channel (PCFICH) is a channel for downlink transmission from a base station to a communication terminal. The PCFICH notifies the number of OFDM (Orthogonal Frequency Division Multiplexing) symbols used for PDCCHs from the base station to the communication terminal. The PCFICH is transmitted for each subframe.

[0008] The Physical Downlink Control Channel (PDCCH) is a channel for downlink transmission from a base station to a communication terminal. The PDCCH notifies resource allocation information of the Downlink Shared Channel (DL-SCH), which is one of the transport channels described later, resource allocation information of the Paging Channel (PCH), which is one of the transport channels described later, and HARQ (Hybrid Automatic Repeat reQuest) information related to the DL-SCH. The PDCCH carries an Uplink Scheduling Grant. The PDCCH carries an Ack (Acknowledgement) / Nack (Negative Acknowledgement), which is a response signal for uplink transmission. The PDCCH is also called an L1 / L2 control signal.

[0009] The Physical Downlink Shared Channel (PDSCH) is a channel for downlink transmission from a base station to a communication terminal. The DL-SCH, which is a transport channel, and the PCH, which is a transport channel, are mapped to the PDSCH.

[0010] The Physical Multicast Channel (PMCH) is a channel for downlink transmission from a base station to a communication terminal. The Multicast Channel (MCH), which is a transport channel, is mapped to the PMCH.

[0011] The Physical Uplink Control Channel (PUCCH) is a channel for uplink transmission from a communication terminal to a base station. The PUCCH carries an Ack / Nack, which is a response signal for downlink transmission. The PUCCH carries CSI (Channel State Information). The CSI consists of an RI (Rank Indicator), a PMI (Precoding Matrix Indicator), and a CQI (Channel Quality Indicator) report. The RI is rank information of a channel matrix in MIMO. The PMI is information on a precoding weight matrix used in MIMO. The CQI is quality information indicating the quality of received data or the channel quality. The PUCCH also carries a Scheduling Request (SR).

[0012] The Physical Uplink Shared Channel (PUSCH) is a channel for uplink transmission from a communication terminal to a base station. The Uplink Shared Channel (UL-SCH), which is one of the transport channels, is mapped to the PUSCH.

[0013] The Physical Hybrid ARQ Indicator Channel (PHICH) is a channel for downlink transmission from the base station to the communication terminal. PHICH carries the Ack / Nack, which is a response signal to the uplink transmission. The Physical Random Access Channel (PRACH) is a channel for uplink transmission from the communication terminal to the base station. PRACH carries the random access preamble.

[0014] The downlink reference signal (Reference Signal: RS) is a symbol known in the LTE communication system. The following five types of downlink reference signals are defined: the Cell-specific Reference Signal (CRS), the MBSFN Reference Signal, the Demodulation Reference Signal (DM-RS) which is the UE-specific Reference Signal, the Positioning Reference Signal (PRS), and the Channel State Information Reference Signal (CSI-RS). As a measurement of the physical layer of the communication terminal, there is the measurement of the Reference Signal Received Power (RSRP) of the reference signal.

[0015] Similarly, for the uplink reference signal, it is a symbol known in the LTE communication system. The following two types of uplink reference signals are defined: the Demodulation Reference Signal (DM-RS) and the Sounding Reference Signal (SRS).

[0016] The transport channel described in Non-Patent Document 1 (Chapter 5) will be explained. Among the downlink transport channels, the broadcast channel (BCH) is broadcast throughout the coverage area of the base station (cell). The BCH is mapped to the physical broadcast channel (PBCH).

[0017] For the downlink shared channel (DL-SCH), retransmission control by hybrid automatic repeat request (HARQ) is applied. The DL-SCH can be broadcast throughout the coverage area of the base station (cell). The DL-SCH supports dynamic or semi-static resource allocation. Semi-static resource allocation is also called persistent scheduling. The DL-SCH supports discontinuous reception (DRX) of the communication terminal for power consumption reduction of the communication terminal. The DL-SCH is mapped to the physical downlink shared channel (PDSCH).

[0018] The paging channel (PCH) supports DRX of the communication terminal to enable low power consumption of the communication terminal. The PCH requires broadcast throughout the coverage area of the base station (cell). The PCH is mapped to a physical resource such as the physical downlink shared channel (PDSCH) that can be dynamically used for traffic.

[0019] The multicast channel (MCH) is used for broadcast throughout the coverage area of the base station (cell). The MCH supports single-frequency network (SFN) combining of the multimedia broadcast multicast service (MBMS) services (MTCH and MCCH) in multi-cell transmission. The MCH supports semi-static resource allocation. The MCH is mapped to the PMCH.

[0020] Among the uplink transport channels, for the uplink shared channel (UL-SCH), hybrid automatic repeat request (HARQ) retransmission control is applied. UL-SCH supports dynamic or semi-static resource allocation. UL-SCH is mapped to the physical uplink shared channel (PUSCH).

[0021] The random access channel (RACH) is limited to control information. RACH has a risk of collision. RACH is mapped to the physical random access channel (PRACH).

[0022] An explanation of HARQ is as follows. HARQ is a technology that improves the communication quality of the transmission path through a combination of automatic repeat request (ARQ) and forward error correction. HARQ has the advantage that error correction functions effectively by retransmission even for a transmission path where the communication quality changes. In particular, it is also possible to obtain further quality improvement by combining the reception result of the first transmission and the reception result of the retransmission during retransmission.

[0023] An example of the retransmission method is explained. At the receiving side, if the received data cannot be decoded correctly, in other words, if a cyclic redundancy check (CRC) error occurs (CRC = NG), the receiving side sends a "Nack" to the transmitting side. The transmitting side that receives the "Nack" retransmits the data. At the receiving side, if the received data can be decoded correctly, in other words, if no CRC error occurs (CRC = OK), the receiving side sends an "Ack" to the transmitting side. The transmitting side that receives the "Ack" transmits the next data.

[0024] The logical channel (Logical channel) described in Non-Patent Document 1 (Chapter 6) will be explained. The Broadcast Control Channel (BCCH) is a downlink channel for broadcast system control information. The BCCH, which is a logical channel, is mapped to the Broadcast Channel (BCH), which is a transport channel, or to the Downlink Shared Channel (DL-SCH).

[0025] The Paging Control Channel (PCCH) is a downlink channel for transmitting paging information and changes in system information. The PCCH is used when the network does not know the cell location of the communication terminal. The PCCH, which is a logical channel, is mapped to the Paging Channel (PCH), which is a transport channel.

[0026] The Common Control Channel (CCCH) is a channel for transmission control information between a communication terminal and a base station. The CCCH is used when the communication terminal does not have an RRC connection with the network. In the downlink direction, the CCCH is mapped to the Downlink Shared Channel (DL-SCH), which is a transport channel. In the uplink direction, the CCCH is mapped to the Uplink Shared Channel (UL-SCH), which is a transport channel.

[0027] The Multicast Control Channel (MCCH) is a downlink channel for one-to-many transmission. The MCCH is used for transmitting MBMS control information for one or several MTCHs from the network to the communication terminal. The MCCH is used only for communication terminals receiving MBMS. The MCCH is mapped to the Multicast Channel (MCH), which is a transport channel.

[0028] The Dedicated Control Channel (DCCH) is a channel that transmits dedicated control information between a communication terminal and a network on a one-to-one basis. The DCCH is used when the communication terminal has an RRC connection. The DCCH is mapped to the UL-SCH in the uplink and to the DL-SCH in the downlink.

[0029] The Dedicated Traffic Channel (DTCH) is a channel for one-to-one communication to an individual communication terminal for transmitting user information. The DTCH exists in both the uplink and the downlink. The DTCH is mapped to the UL-SCH in the uplink and to the DL-SCH in the downlink.

[0030] The Multicast Traffic Channel (MTCH) is a downlink channel for transmitting traffic data from the network to a communication terminal. The MTCH is a channel used only by communication terminals during MBMS reception. The MTCH is mapped to the Multicast Channel (MCH).

[0031] CGI stands for Cell Global Identifier. ECGI stands for E-UTRAN Cell Global Identifier. In LTE, LTE-A (Long Term Evolution Advanced) to be described later, and UMTS (Universal Mobile Telecommunication System), Closed Subscriber Group (CSG) cells are introduced.

[0032] The location tracking of a communication terminal is performed in units of an area composed of one or more cells. The location tracking is performed to track the location of the communication terminal even in the standby state and to enable calling the communication terminal, in other words, to enable the communication terminal to receive an incoming call. The area for this location tracking of the communication terminal is called a tracking area.

[0033] Also, in 3GPP, as Release 10, the standardization of Long Term Evolution Advanced (LTE-A) is in progress (see Non-Patent Document 3 and Non-Patent Document 4). LTE-A is based on the radio interval communication method of LTE and is configured by adding several new technologies thereto.

[0034] In the LTE-A system, in order to support a wider frequency bandwidth (transmission bandwidths) up to 100 MHz, carrier aggregation (CA) is being studied, which aggregates (also referred to as "aggregation") two or more component carriers (CC). CA is described in Non-Patent Document 1.

[0035] When CA is configured, the UE has only one RRC connection with the network (NW). In the RRC connection, one serving cell provides NAS mobility information and security input. This cell is called the primary cell (PCell). In the downlink, the carrier corresponding to the PCell is the downlink primary component carrier (DL PCC). In the uplink, the carrier corresponding to the PCell is the uplink primary component carrier (UL PCC).

[0036] According to the capabilities of the UE, a Secondary Cell (SCell) is configured to form a set of serving cells together with the PCell. In the downlink, the carrier corresponding to the SCell is the Downlink Secondary Component Carrier (DL SCC). In the uplink, the carrier corresponding to the SCell is the Uplink Secondary Component Carrier (UL SCC).

[0037] A set of serving cells consisting of one PCell and one or more SCells is configured for one UE.

[0038] Also, as new technologies in LTE-A, there are technologies such as Wider bandwidth extension and Coordinated Multiple Point transmission and reception (CoMP). Regarding CoMP being considered for LTE-A by 3GPP, it is described in Non-Patent Document 1.

[0039] Also, in 3GPP, in order to handle future massive traffic, it is being considered to use small eNBs (hereinafter sometimes referred to as "small base station devices") that constitute small cells. For example, technologies such as increasing the frequency utilization efficiency and increasing the communication capacity by installing a large number of small eNBs to form a large number of small cells are being considered. Specifically, there is Dual Connectivity (abbreviated as DC) where a UE connects to two eNBs for communication. Regarding DC, it is described in Non-Patent Document 1.

[0040] Among the eNBs that perform dual connectivity (DC), one may be referred to as the "master eNB (abbreviated as MeNB)", and the other may be referred to as the "secondary eNB (abbreviated as SeNB)".

[0041] The traffic volume of mobile networks is on an increasing trend, and the communication speed is also accelerating. When LTE and LTE-A are fully launched into operation, it is expected that the communication speed will be further increased.

[0042] Furthermore, a fifth-generation (hereinafter sometimes referred to as "5G") radio access system, which aims to start services after 2020, is being studied for advanced mobile communications. For example, in Europe, the requirements for 5G have been summarized by a group called METIS (see Non-Patent Document 5).

[0043] In the 5G radio access system, compared with the LTE system, the system capacity is 1000 times, the data transmission speed is 100 times, the data processing delay is one-tenth (1 / 10), and the number of simultaneously connected communication terminals is 100 times. Further reduction of power consumption and cost of devices are listed as requirements.

[0044] In order to meet such requirements, in 3GPP, the standard study of 5G is being advanced as Release 15 (see Non-Patent Documents 6 to 18). The technology of the 5G radio section is called "New Radio Access Technology" (abbreviated as "NR" for "New Radio").

[0045] The NR system is being studied based on the LTE system and the LTE-A system, but changes and additions from the LTE system and the LTE-A system are being made in the following aspects.

[0046] As the access method of NR, OFDM is used in the downlink direction, and OFDM and DFT-s-OFDM (DFT-spread-OFDM) are used in the uplink direction.

[0047] In NR, in order to improve the transmission speed and reduce the processing delay, it is possible to use a higher frequency compared to LTE.

[0048] In NR, by forming a narrow beam-like transmission and reception range (beamforming) and changing the direction of the beam (beam sweeping), cell coverage is ensured.

[0049] In the frame structure of NR, various subcarrier intervals, that is, various numerologies are supported. In NR, regardless of the numerology, one subframe is 1 millisecond, and one slot is composed of 14 symbols. Also, the number of slots included in one subframe is one in the numerology with a subcarrier interval of 15 kHz, and in other numerologies, it increases in proportion to the subcarrier interval (see Non-Patent Document 13 (TS38.211 V15.2.0)).

[0050] The downlink synchronization signal in NR is transmitted from the base station at a predetermined period with a predetermined duration as a Synchronization Signal Burst (hereinafter, may be referred to as an SS burst). The SS burst is composed of Synchronization Signal Blocks (hereinafter, may be referred to as SS blocks) for each beam of the base station. The base station transmits the SS blocks of each beam within the duration of the SS burst while changing the beam. The SS block is composed of P-SS, S-SS, and PBCH.

[0051] In NR, as a downlink reference signal in NR, by adding a Phase Tracking Reference Signal (PTRS), the influence of phase noise is reduced. Also, in the uplink reference signal, PTRS is added in the same way as in the downlink.

[0052] In NR, in order to flexibly perform DL / UL switching within a slot, Slot Format Indication (SFI) is added to the information included in the PDCCH.

[0053] Also, in NR, a part of the carrier frequency band (hereinafter sometimes referred to as Bandwidth Part (BWP)) is preset by the base station for the UE, and the UE performs transmission and reception with the base station in the BWP, thereby reducing the power consumption in the UE.

[0054] In 3GPP, as forms of DC, DC by an LTE base station connected to the EPC and an NR base station, DC by an NR base station connected to the 5G core system, and DC by an LTE base station and an NR base station connected to the 5G core system are being studied (see Non-Patent Documents 12, 16, and 19).

[0055] Also, in 3GPP, several new technologies are being studied. For example, the operation of a terminal using multiple SIM (Subscriber Identity Module) is being studied (see Non-Patent Documents 20 and 21).

Prior Art Documents

Non-Patent Documents

[0056]

Non-Patent Document 1

Non-Patent Document 2

Non-Patent Document 3

Non-Patent Document 4

Non-Patent Document 5

Non-Patent Document 6

Non-Patent Document 7

Non-Patent Document 8

Non-Patent Document 9

Non-Patent Document 10

Non-Patent Document 11

Non-Patent Document 12

Non-Patent Document 13

Non-Patent Document 14

Non-Patent Document 15

Non-Patent Document 16

Non-Patent Document 17

Non-Patent Document 18

Non-Patent Document 19

Non-Patent Document 20

Non-Patent Document 21

Non-Patent Document 22

Non-Patent Document 23

Non-Patent Document 24

Non-Patent Document 25

Non-Patent Document 26

Non-Patent Document 27

Non-Patent Document 28

Summary of the Invention

Problems to be Solved by the Invention

[0057] In 3GPP, the operation of a UE using multiple SIMs has been studied. For example, countermeasures in the case where the paging timings for the UE from two NWs overlap have been studied (see Non-Patent Documents 20 and 21). However, Non-Patent Documents 20 and 21 do not disclose a specific method for avoiding the overlap of paging timings, in other words, paging collisions. Therefore, it becomes impossible to avoid paging collisions between two NWs. As a result, a problem occurs in that the connection between the UE and one NW in the communication system cannot be started quickly.

[0058] In view of the above problems, one of the objectives of the present disclosure is to provide a technology that enables a quick NW connection.

Means for Solving the Problems

[0059] According to the present disclosure, there is provided a terminal device having a plurality of SIMs (Subscriber Identity Modules), wherein the terminal device is configured to connect to a plurality of networks using the plurality of SIMs, and the terminal device is configured to determine a paging collision between the plurality of networks. According to the present disclosure, there is provided a communication system including a terminal device configured to have a plurality of SIMs (Subscriber Identity Modules) and connect to a plurality of networks using the plurality of SIMs, wherein the terminal device is configured to determine a paging collision between the plurality of networks.

Advantages of the Invention

[0060] According to the present disclosure, a rapid NW connection becomes possible.

[0061] The object, features, aspects, and advantages of the present disclosure will become more apparent from the following detailed description and the accompanying drawings.

Brief Description of the Drawings

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Best Mode for Carrying Out the Invention

[0063] Embodiment 1. FIG. 2 is a block diagram showing the overall configuration of a communication system 200 of the LTE system being discussed in 3GPP. FIG. 2 will be described. The radio access network is referred to as E-UTRAN (Evolved Universal Terrestrial Radio Access Network) 201. A mobile terminal device (hereinafter simply referred to as “mobile terminal (User Equipment: UE)”) 202, which is a communication terminal device, can communicate wirelessly with a base station device (hereinafter referred to as “base station (E-UTRAN NodeB: eNB)”) 203 and perform signal transmission and reception through wireless communication.

[0064] Here, the “communication terminal device” includes not only mobile terminal devices such as mobile phone terminal devices that can move, but also devices that do not move such as sensors. In the following description, the “communication terminal device” may sometimes be simply referred to as the “communication terminal”.

[0065] If the control protocol for the mobile terminal 202, for example, RRC (Radio Resource Control), and the user plane (hereinafter sometimes referred to as U-Plane), for example, PDCP (Packet Data Convergence Protocol), RLC (Radio Link Control), MAC (Medium Access Control), PHY (Physical layer) terminate at the base station 203, then the E-UTRAN is composed of one or more base stations 203.

[0066] The control protocol RRC (Radio Resource Control) between the mobile terminal 202 and the base station 203 performs functions such as broadcast, paging, and RRC connection management. As the states of the base station 203 and the mobile terminal 202 in RRC, there are RRC_IDLE and RRC_CONNECTED.

[0067] In the RRC_IDLE state, PLMN (Public Land Mobile Network) selection, system information (SI) notification, paging, cell re-selection, mobility, etc. are performed. In the RRC_CONNECTED state, the mobile terminal has an RRC connection and can transmit and receive data with the network. Also in the RRC_CONNECTED state, handover (HO), measurement of neighboring cells, etc. are performed.

[0068] The base station 203 is composed of one or more eNBs 207. Also, a system composed of the core network EPC (Evolved Packet Core) and the radio access network E-UTRAN 201 is called EPS (Evolved Packet System). Sometimes, the combination of the core network EPC and the radio access network E-UTRAN 201 is referred to as the "network".

[0069] The eNB 207 is connected to the mobility management entity (MME), or the serving gateway (S-GW), or the MME / S-GW unit (hereinafter sometimes referred to as the "MME unit") 204 including the MME and the S-GW through the S1 interface, and control information is communicated between the eNB 207 and the MME unit 204. A plurality of MME units 204 may be connected to one eNB 207. The eNBs 207 are connected through the X2 interface, and control information is communicated between the eNBs 207.

[0070] The MME unit 204 is a higher-level device, specifically a higher-level node, and controls the connection between the base station, namely the eNB 207, and the mobile terminal (UE) 202. The MME unit 204 constitutes the EPC which is the core network. The base station 203 constitutes the E-UTRAN 201.

[0071] The base station 203 may constitute one cell or multiple cells. Each cell has a range predefined as coverage which is a range within which communication with the mobile terminal 202 is possible, and performs wireless communication with the mobile terminal 202 within the coverage. When one base station 203 constitutes multiple cells, each individual cell is configured to enable communication with the mobile terminal 202.

[0072] Figure 3 is a block diagram showing the overall configuration of a 5G communication system 210 being discussed in 3GPP. An explanation will be given regarding Figure 3. The radio access network is referred to as NG-RAN (Next Generation Radio Access Network) 211. The UE 202 can perform wireless communication with an NR base station device (hereinafter referred to as "NR base station (NG-RAN NodeB: gNB)") 213 and transmit and receive signals through wireless communication. Also, the core network is referred to as 5G Core (5GC).

[0073] If the control protocol for the UE 202, such as RRC (Radio Resource Control), and the user plane (hereinafter sometimes referred to as U-Plane), such as SDAP (Service Data Adaptation Protocol), PDCP (Packet Data Convergence Protocol), RLC (Radio Link Control), MAC (Medium Access Control), PHY (Physical layer), terminate at the NR base station 213, then the NG-RAN is constituted by one or multiple NR base stations 213.

[0074] The function of the control protocol RRC (Radio Resource Control) between the UE202 and the NR base station 213 is the same as that of LTE. As the states of the NR base station 213 and the UE202 in RRC, there are RRC_IDLE, RRC_CONNECTED, and RRC_INACTIVE.

[0075] RRC_IDLE and RRC_CONNECTED are the same as the LTE mode. In RRC_INACTIVE, while the connection between the 5G core and the NR base station 213 is maintained, system information (SI) notification, paging, cell re-selection, mobility, etc. are performed.

[0076] The gNB217 is connected to the AMF / SMF / UPF unit (hereinafter sometimes referred to as the "5GC unit") 214 including the Access and Mobility Management Function (AMF), Session Management Function (SMF), or UPF, or AMF, SMF, and UPF through the NG interface. Control information and / or user data are communicated between the gNB217 and the 5GC unit 214. The NG interface is a general term for the N2 interface between the gNB217 and the AMF, the N3 interface between the gNB217 and the UPF, the N11 interface between the AMF and the SMF, and the N4 interface between the UPF and the SMF. For one gNB217, a plurality of 5GC units 214 may be connected. The gNB217s are connected by the Xn interface, and control information and / or user data are communicated between the gNB217s.

[0077] Similar to the base station 203, the NR base station 213 may also constitute one or more cells. When one NR base station 213 constitutes a plurality of cells, each cell is configured to be able to communicate with the UE202.

[0078] gNB 217 may be divided into a Central Unit (hereinafter sometimes referred to as CU) 218 and a Distributed Unit (hereinafter sometimes referred to as DU) 219. One CU 218 is configured within gNB 217. One or more DUs 219 are configured within gNB 217. The CU 218 is connected to the DU 219 via an F1 interface, and control information and / or user data are communicated between the CU 218 and the DU 219.

[0079] In a 5G communication system, a Unified Data Management (UDM) function and a Policy Control Function (PCF) described in Non-Patent Document 22 (3GPP TS23.501 V16.1.0) may be included. The UDM and / or the PCF may be included in the 5GC part in FIG. 3.

[0080] In a 5G communication system, a Non-3GPP Interworking Function (N3IWF) described in Non-Patent Document 22 (3GPP TS23.501 V16.1.0) may be included. The N3IWF may terminate the access network (AN) between the UE in non-3GPP access with the UE.

[0081] FIG. 4 is a diagram showing the configuration of DC by an eNB and a gNB connected to the EPC. In FIG. 4, solid lines indicate U-Plane connections, and dashed lines indicate C-Plane connections. In FIG. 4, eNB 223-1 becomes the master base station, and gNB 224-2 becomes the secondary base station (this DC configuration may sometimes be referred to as EN-DC). In FIG. 4, an example is shown in which the U-Plane connection between the MME part 204 and the gNB 224-2 is made via the eNB 223-1, but it may be made directly between the MME part 204 and the gNB 224-2.

[0082] FIG. 5 is a diagram showing the configuration of DC by a gNB connected to an NG core. In FIG. 5, solid lines indicate U-Plane connections, and dashed lines indicate C-Plane connections. In FIG. 5, gNB224-1 becomes the master base station, and gNB224-2 becomes the secondary base station (this DC configuration may be referred to as NR-DC). In FIG. 5, an example is shown in which the U-Plane connection between the 5GC unit 214 and gNB224-2 is made via gNB224-1, but it may also be made directly between the 5GC unit 214 and gNB224-2.

[0083] FIG. 6 is a diagram showing the configuration of DC by an eNB and a gNB connected to an NG core. In FIG. 6, solid lines indicate U-Plane connections, and dashed lines indicate C-Plane connections. In FIG. 6, eNB226-1 becomes the master base station, and gNB224-2 becomes the secondary base station (this DC configuration may be referred to as NG-EN-DC). In FIG. 6, an example is shown in which the U-Plane connection between the 5GC unit 214 and gNB224-2 is made via eNB226-1, but it may also be made directly between the 5GC unit 214 and gNB224-2.

[0084] FIG. 7 is a diagram showing another configuration of DC by an eNB and a gNB connected to an NG core. In FIG. 7, solid lines indicate U-Plane connections, and dashed lines indicate C-Plane connections. In FIG. 7, gNB224-1 becomes the master base station, and eNB226-2 becomes the secondary base station (this DC configuration may be referred to as NE-DC). In FIG. 7, an example is shown in which the U-Plane connection between the 5GC unit 214 and eNB226-2 is made via gNB224-1, but it may also be made directly between the 5GC unit 214 and eNB226-2.

[0085] FIG. 8 is a block diagram showing the configuration of the mobile terminal 202 shown in FIG. 2. The transmission process of the mobile terminal 202 shown in FIG. 8 will be described. First, the control data from the protocol processing unit 301 and the user data from the application unit 302 are stored in the transmission data buffer unit 303. The data stored in the transmission data buffer unit 303 is passed to the encoder unit 304, and encoding processes such as error correction are performed. There may be data that is directly output from the transmission data buffer unit 303 to the modulation unit 305 without undergoing encoding processing. The data encoded by the encoder unit 304 is subjected to modulation processing by the modulation unit 305. In the modulation unit 305, precoding in MIMO may be performed. The modulated data is converted into a baseband signal and then output to the frequency conversion unit 306, where it is converted to a wireless transmission frequency. Thereafter, transmission signals are transmitted from the antennas 307-1 to 307-4 to the base station 203. In FIG. 8, the case where the number of antennas is four is illustrated, but the number of antennas is not limited to four.

[0086] Also, the reception process of the mobile terminal 202 is executed as follows. The wireless signals from the base station 203 are received by the antennas 307-1 to 307-4. The received signals are converted from the wireless reception frequency to a baseband signal by the frequency conversion unit 306, and demodulation processing is performed in the demodulation unit 308. In the demodulation unit 308, weight calculation and multiplication processing may be performed. The demodulated data is passed to the decoder unit 309, and decoding processes such as error correction are performed. Among the decoded data, the control data is passed to the protocol processing unit 301, and the user data is passed to the application unit 302. A series of processes of the mobile terminal 202 are controlled by the control unit 310. Therefore, although omitted in FIG. 8, the control unit 310 is connected to each of the units 301 to 309. In FIG. 8, the number of antennas used for transmission and the number of antennas used for reception by the mobile terminal 202 may be the same or different.

[0087] FIG. 9 is a block diagram showing the configuration of the base station 203 shown in FIG. 2. The transmission process of the base station 203 shown in FIG. 9 will be described. The EPC communication unit 401 transmits and receives data between the base station 203 and the EPC (such as the MME unit 204). The 5GC communication unit 412 transmits and receives data between the base station 203 and the 5GC (such as the 5GC unit 214). The other base station communication unit 402 transmits and receives data with other base stations. The EPC communication unit 401, the 5GC communication unit 412, and the other base station communication unit 402 each exchange information with the protocol processing unit 403. The control data from the protocol processing unit 403, as well as the user data and control data from the EPC communication unit 401, the 5GC communication unit 412, and the other base station communication unit 402, are stored in the transmission data buffer unit 404.

[0088] The data stored in the transmission data buffer unit 404 is passed to the encoder unit 405, and encoding processes such as error correction are performed. There may be data that is directly output from the transmission data buffer unit 404 to the modulation unit 406 without undergoing the encoding process. The encoded data is subjected to modulation processing in the modulation unit 406. Precoding in MIMO may be performed in the modulation unit 406. The modulated data is converted into a baseband signal and then output to the frequency conversion unit 407, where it is converted to a radio transmission frequency. Thereafter, a transmission signal is transmitted to one or more mobile terminals 202 from the antennas 408-1 to 408-4. In FIG. 9, the case where the number of antennas is four is illustrated, but the number of antennas is not limited to four.

[0089] Also, the reception processing of the base station 203 is executed as follows. A radio signal from one or more mobile terminals 202 is received by the antenna 408. The received signal is converted from the radio reception frequency to a baseband signal by the frequency conversion unit 407, and demodulation processing is performed by the demodulation unit 409. The demodulated data is passed to the decoder unit 410, and decoding processing such as error correction is performed. Among the decoded data, the control data is passed to the protocol processing unit 403, the 5GC communication unit 412, the EPC communication unit 401, or the other base station communication unit 402, and the user data is passed to the 5GC communication unit 412, the EPC communication unit 401, and the other base station communication unit 402. A series of processes of the base station 203 is controlled by the control unit 411. Therefore, although omitted in FIG. 9, the control unit 411 is connected to each unit 401 to 410. In FIG. 9, the number of antennas used for transmission and the number of antennas used for reception by the base station 203 may be the same or different.

[0090] FIG. 9 is a block diagram showing the configuration of the base station 203, but the base station 213 may have a similar configuration. Also, regarding FIGS. 8 and 9, the number of antennas of the mobile terminal 202 and the number of antennas of the base station 203 may be the same or different.

[0091] FIG. 10 is a block diagram showing the configuration of the MME. FIG. 10 shows the configuration of the MME204a included in the MME unit 204 shown in FIG. 2 described above. The PDN GW communication unit 501 performs data transmission and reception between the MME204a and the PDN GW. The base station communication unit 502 performs data transmission and reception via the S1 interface between the MME204a and the base station 203. When the data received from the PDN GW is user data, the user data is passed from the PDN GW communication unit 501 to the base station communication unit 502 via the user plain communication unit 503 and transmitted to one or more base stations 203. When the data received from the base station 203 is user data, the user data is passed from the base station communication unit 502 to the PDN GW communication unit 501 via the user plain communication unit 503 and transmitted to the PDN GW.

[0092] When the data received from the PDN GW is control data, the control data is passed from the PDN GW communication unit 501 to the control plane control unit 505. When the data received from the base station 203 is control data, the control data is passed from the base station communication unit 502 to the control plane control unit 505.

[0093] The control plane control unit 505 includes an NAS security unit 505-1, an SAE bearer control unit 505-2, an idle state mobility management unit 505-3, etc., and performs overall processing for the control plane (hereinafter, may also be referred to as the C-Plane). The NAS security unit 505-1 performs security of NAS (Non-Access Stratum) messages, etc. The SAE bearer control unit 505-2 performs management of SAE (System Architecture Evolution) bearers, etc. The idle state mobility management unit 505-3 performs mobility management in the standby state (idle state; LTE-IDLE state, or simply referred to as idle), generation and control of paging signals in the standby state, addition, deletion, update, search, and tracking area list management of one or more tracking areas of the subordinate mobile terminals 202.

[0094] The MME 204a distributes paging signals to one or more base stations 203. Also, the MME 204a performs mobility control in the Idle State. The MME 204a manages the Tracking Area list when the mobile terminal is in the idle state and when it is in the Active State. The MME 204a initiates the paging protocol by transmitting a paging message to a cell belonging to the tracking area (Tracking Area) in which the UE is registered. The management of the CSG of the eNB 207 connected to the MME 204a, the management of the CSG ID, and the management of the white list may be performed by the idle state mobility management unit 505-3.

[0095] FIG. 11 is a block diagram showing the configuration of the 5GC. In FIG. 11, the configuration of the 5GC unit 214 shown in FIG. 3 described above is shown. FIG. 11 shows the case where the configuration of the AMF, the configuration of the SMF, and the configuration of the UPF are included in the 5GC unit 214 shown in FIG. 5. The Data Network communication unit 521 transmits and receives data between the 5GC unit 214 and the Data Network. The base station communication unit 522 transmits and receives data via the S1 interface between the 5GC unit 214 and the base station 203 and / or the NG interface between the 5GC unit 214 and the base station 213. When the data received from the Data Network is user data, the user data is passed from the Data Network communication unit 521 to the base station communication unit 522 via the user plain communication unit 523 and transmitted to one or more base stations 203 and / or base stations 213. When the data received from the base station 203 and / or base station 213 is user data, the user data is passed from the base station communication unit 522 to the Data Network communication unit 521 via the user plain communication unit 523 and transmitted to the Data Network.

[0096] When the data received from the Data Network is control data, the control data is passed from the Data Network communication unit 521 to the session management unit 527 via the user plane control unit 523. The session management unit 527 passes the control data to the control plane control unit 525. When the data received from the base station 203 and / or the base station 213 is control data, the control data is passed from the base station communication unit 522 to the control plane control unit 525. The control plane control unit 525 passes the control data to the session management unit 527.

[0097] The control plane control unit 525 includes a NAS security unit 525-1, a PDU session control unit 525-2, an idle state mobility management unit 525-3, etc., and performs all processes for the control plane (hereinafter, may also be referred to as the C-Plane). The NAS security unit 525-1 performs security of NAS (Non-Access Stratum) messages, etc. The PDU session control unit 525-2 performs management of PDU sessions between the mobile terminal 202 and the 5GC unit 214, etc. The idle state mobility management unit 525-3 performs mobility management in the standby state (idle state; RRC_IDLE state, or simply referred to as idle), generation and control of paging signals in the standby state, addition, deletion, update, search, and tracking area list management of one or more tracking areas under its umbrella for the mobile terminal 202.

[0098] The 5GC unit 214 distributes paging signals to one or more base stations 203 and / or base station 213. Also, the 5GC unit 214 performs mobility control in the idle state. When the mobile terminal is in the idle state, the 5GC unit 214 manages the tracking area list in the inactive state and the active state. The 5GC unit 214 initiates the paging protocol by transmitting a paging message to a cell belonging to the tracking area (tracking area) where the UE is registered.

[0099] Next, an example of a cell search method in a communication system is shown. FIG. 12 is a flowchart showing an overview from cell search to standby operation performed by a communication terminal (UE) in an LTE-based communication system. When the communication terminal starts cell search, in step ST601, it synchronizes slot timing and frame timing using the first synchronization signal (P-SS) and the second synchronization signal (S-SS) transmitted from surrounding base stations.

[0100] The P-SS and S-SS are combined and called the synchronization signal (SS). A synchronization code corresponding one-to-one to the PCI assigned to each cell is assigned to the synchronization signal (SS). 504 types of PCI are being considered. Synchronization is performed using these 504 types of PCI, and the PCI of the cell that has been synchronized is detected (identified).

[0101] Next, for the cell that has been synchronized, in step ST602, a Cell-specific Reference Signal (CRS), which is a reference signal (Reference Signal: RS) transmitted from the base station for each cell, is detected, and the received power of the RS (Reference Signal Received Power: RSRP) is measured. A code corresponding one-to-one to the PCI is used for the reference signal (RS). By correlating with that code, it can be separated from other cells. By deriving the code for the RS of the cell from the PCI specified in step ST601, it becomes possible to detect the RS and measure the received power of the RS.

[0102] Next, in step ST603, from among the one or more cells detected up to step ST602, a cell with the best reception quality of the RS is selected, for example, a cell with the highest received power of the RS, that is, the best cell.

[0103] Next, in step ST604, the PBCH of the best cell is received to obtain the BCCH, which is the broadcast information. The MIB (Master Information Block), which contains the cell configuration information, is mapped to the BCCH on the PBCH. Therefore, by receiving the PBCH and obtaining the BCCH, the MIB can be obtained. Examples of the information in the MIB include the DL (downlink) system bandwidth (also called the transmission bandwidth configuration: dl-bandwidth), the number of transmission antennas, the SFN (System Frame Number), and the like.

[0104] Next, in step ST605, based on the cell configuration information in the MIB, the DL-SCH of the cell is received to obtain SIB (System Information Block) 1 in the broadcast information BCCH. SIB1 contains information related to access to the cell, information related to cell selection, and scheduling information for other SIBs (SIBk; k is an integer greater than or equal to 2). In addition, SIB1 contains the Tracking Area Code (TAC).

[0105] Next, in step ST606, the communication terminal compares the TAC of SIB1 received in step ST605 with the TAC part of the tracking area identifier (Tracking Area Identity: TAI) in the tracking area list that the communication terminal already has. The tracking area list is also referred to as the TAI list. The TAI is identification information for identifying a tracking area and is composed of an MCC (Mobile Country Code), an MNC (Mobile Network Code), and a TAC (Tracking Area Code). The MCC is a country code. The MNC is a network code. The TAC is a code number of the tracking area.

[0106] As a result of the comparison in step ST606, if the TAC received in step ST605 is the same as the TAC included in the tracking area list, the communication terminal enters the standby operation in the cell. If the comparison shows that the TAC received in step ST605 is not included in the tracking area list, the communication terminal requests a change of the tracking area through the cell to perform a TAU (Tracking Area Update) to the core network (Core Network, EPC) including an MME or the like.

[0107] In the example shown in FIG. 12, an example of the operation from cell search to standby in the LTE system has been shown. In the NR system, in step ST603, in addition to the best cell, the best beam may be selected. Also, in the NR system, in step ST604, beam information, for example, a beam identifier may be acquired. Further, in the NR system, in step ST604, scheduling information of the Remaining Minimum SI (RMSI) may be acquired. In the NR system, in step ST605, it may be assumed that the RMSI is received.

[0108] The device that constitutes the core network (hereinafter sometimes referred to as the "core network side device") updates the tracking area list based on the identification number (such as UE-ID) of the communication terminal sent from the communication terminal together with the TAU request signal. The core network side device transmits the updated tracking area list to the communication terminal. The communication terminal rewrites (updates) the TAC list held by the communication terminal based on the received tracking area list. Thereafter, the communication terminal enters the standby operation in the cell.

[0109] Due to the spread of smartphones and tablet terminal devices, the traffic by cellular wireless communication has increased explosively, and there is a concern about the shortage of radio resources worldwide. In response to this, in order to improve the frequency utilization efficiency, it is being considered to miniaturize the cells and proceed with spatial separation.

[0110] In the configuration of a conventional cell, the cell constituted by an eNB has a relatively wide coverage area. Conventionally, cells have been configured to cover a certain area by the relatively wide coverage areas of a plurality of cells constituted by a plurality of eNBs.

[0111] When miniaturized, the cell constituted by an eNB has a coverage area that is narrower than the coverage area of a cell constituted by a conventional eNB. Therefore, in order to cover a certain area as in the conventional case, a larger number of miniaturized eNBs are required compared to conventional eNBs.

[0112] In the following description, a cell with a relatively large coverage area, such as a cell constituted by a conventional eNB, is referred to as a "macro cell", and the eNB that constitutes the macro cell is referred to as a "macro eNB". Also, a cell with a relatively small coverage area, such as a miniaturized cell, is referred to as a "small cell", and the eNB that constitutes the small cell is referred to as a "small eNB".

[0113] The macro eNB may be, for example, a "Wide Area Base Station" described in Non-Patent Document 7.

[0114] The small eNB may be, for example, a low-power node, a local area node, a hot spot, etc. Also, the small eNB may be a pico eNB that constitutes a pico cell, a femto eNB that constitutes a femto cell, a HeNB, an RRH (Remote Radio Head), an RRU (Remote Radio Unit), an RRE (Remote Radio Equipment), or an RN (Relay Node). Further, the small eNB may be a "Local Area Base Station" or a "Home Base Station" described in Non-Patent Document 7.

[0115] FIG. 13 shows an example of the configuration of a cell in NR. In the NR cell, a narrow beam is formed and transmitted while changing the direction. In the example shown in FIG. 13, at a certain time, the base station 750 performs transmission and reception with the mobile terminal using the beam 751-1. At other times, the base station 750 performs transmission and reception with the mobile terminal using the beam 751-2. Similarly hereinafter, the base station 750 performs transmission and reception with the mobile terminal using one or more of the beams 751-3 to 751-8. By doing so, the base station 750 constitutes a wide range of cells.

[0116] In FIG. 13, an example in which the number of beams used by the base station 750 is 8 is shown, but the number of beams may be different from 8. Also, in the example shown in FIG. 13, the number of beams used by the base station 750 at the same time is set to 1, but it may be plural.

[0117] The UE may be connected to multiple NWs or may be in a connectable state (hereinafter, "connection" may include not only the actually connected state but also the connectable state). The UE may connect to the multiple NWs using multiple SIMs. The UE may have only one set of transceivers or may have multiple sets of transceivers. The multiple NWs may be a PLMN or a Non-Public Network (NPN). The connection to the multiple NWs may be performed in parallel.

[0118] Regarding the connection between the UE and each NW, the RRC state of the UE may be the RRC_CONNECTED state, the RRC_INACTIVE state, or the RRC_IDLE state. The CM state of the UE may be CM-IDLE or CM-CONNECTED. The UE may be in the RRC_CONNECTED state or the CM-CONNECTED state with respect to two or more of the multiple connected NWs. As another example, the UE may be in the RRC_CONNECTED state or the CM-CONNECTED state only with respect to one of the multiple connected NWs.

[0119] FIG. 14 is an architecture diagram showing an example of the connection between a UE using multiple SIMs (hereinafter, may be referred to as a multi-SIM UE) and multiple NWs. In FIG. 14, the multi-SIM UE is connected in parallel to PLMN#1 and PLMN#2.

[0120] In the example shown in FIG. 14, the UE 1400 connects to the gNB 1401 in PLMN#1. Also, the UE 1400 connects to the gNB 1411 in PLMN#2. The gNB 1401 connects to the AMF 1402 and UPF 1403 in PLMN#1. The SMF 1404 in PLMN#1 connects to the AMF 1402 and UPF 1403. The gNB 1411 connects to the AMF 1412 and UPF 1413 in PLMN#2. The SMF 1414 in PLMN#2 connects to the AMF 1412 and UPF 1413.

[0121] In the example shown in FIG. 14, the case where the UE 1400 connects to two PLMNs is shown, but the UE 1400 may connect to three or more PLMNs. Also, among the two NWs to which the UE 1400 connects, one or more of them may be an NPN. The same may apply when the UE 1400 connects to three or more NWs.

[0122] In a UE that is connected in parallel to multiple NWs, there may be a case where the paging timings overlap (hereinafter, may be referred to as paging collision). The UE in which paging collision occurs may be a UE having only one set of transceivers. In this case, no specific method for avoiding paging collision is disclosed. Therefore, each device in the communication system cannot avoid paging for the UE. As a result, there arises a problem that the UE cannot receive paging from one or more of the aforementioned NWs.

[0123] In the first embodiment, a method for solving the aforementioned problem is disclosed.

[0124] The UE detects paging collisions from multiple NWs. The UE may perform the detection using the frame timing in each NW and the timing related to paging (hereinafter may be referred to as paging timing). The UE may determine that paging has collided when the timings related to paging in multiple NWs overlap in real time. The UE may correct the paging timing in each NW using the frame timing in each NW. The UE may perform the detection using the corrected paging timing. By performing the detection using the frame timing, the UE can detect paging collisions even when the frame timings of each NW are different, for example.

[0125] The UE may obtain the frame timing in the base station of each NW using cell search. The UE may obtain the timing related to paging in each NW using the system information notified from the base station of each NW and the identifier of the UE assigned to the UE itself from each NW. The timing related to paging may be a PF (Paging Frame), a PO (Paging Occasion), a PDCCH monitoring occasion used for paging reception, or a combination of multiple of the above.

[0126] The UE may use PF, PO, or PDCCH monitoring occasion for the detection of paging collisions, or use multiple of the above. For example, by using PF for the detection, the UE can reduce the processing amount related to the detection. As another example, by using a combination of PF, PO, and PDCCH monitoring occasion for the detection, the UE can improve the accuracy of the detection.

[0127] FIG. 15 shows an example of paging collision from multiple NWs. FIG. 15 shows the case where the UE is connected to NW#1 and NW#2. In FIG. 15, the horizontal axis represents time.

[0128] At the time of arrow 1501 shown in FIG. 15, the SFN of NW#1 becomes 0. At the time of arrow 1502, the SFN of NW#2 becomes 0. The paging timing of the UE in NW#1 is arranged in section 1505, and the paging timing of the UE in NW#2 is arranged in section 1506.

[0129] In the example shown in FIG. 15, section 1505 and section 1506 overlap in time in section 1508 indicated by the dashed line. In this case, the UE determines that a paging collision has occurred.

[0130] In the example shown in FIG. 15, the paging timing may be a PF (Paging Frame), a PO (Paging Occasion), a PDCCH monitoring occasion for paging reception, or a combination of multiple of the above.

[0131] As another example of paging collision detection in the UE, when the period of N periods of the SS burst cycle in the base station of one NW overlaps with the paging timing in the base station of another NW, a paging collision may be considered to have occurred. The above-mentioned N may be 0, 1, or 2 or more. The above-mentioned N may be determined by the standard, or may be determined by the UE. The above-mentioned N may be determined by the base station, for example, the base station that transmits the paging received by the UE, and notified to the UE. As a result, for example, the UE can establish downlink synchronization with the base station that transmits the paging. As a result, the UE can quickly acquire the paging.

[0132] The UE notifies the NW of the paging collision. The UE may include in the notification the information necessary for avoiding the paging collision. The UE may request the NW to avoid the paging collision. The aforementioned information may be included in the request.

[0133] The UE may send the notification to the base station. For example, the UE may send the notification to the base station with earlier PRACH transmission timing among the base stations of multiple NWs. Thereby, for example, the UE can quickly connect to any one of the multiple NWs, and as a result, the paging collision can be quickly avoided.

[0134] The UE may send the notification to the base station of one NW. Thereby, for example, in a communication system, the paging collision avoidance can be executed with a small amount of signaling. As another example, the UE may send the notification to the base stations of multiple NWs. Thereby, for example, in a communication system, the flexibility of paging timing change can be improved.

[0135] The UE may send the notification using RRC signaling. For example, the UE may use the RRC setup request (RRCSetupRequest) for the notification. Thereby, for example, the UE can quickly send the notification to the base station. As another example, the UE may use the RRC setup complete (RRCSetupComplete) for the notification. Thereby, for example, the UE can notify the base station including a lot of information.

[0136] As another example, the UE may use the RRC resume request (RRCResumeRequest) for the notification. Thereby, for example, the UE can quickly send the notification to the base station. As another example, the UE may use the RRC resume complete (RRCResumeComplete) for the notification. Thereby, for example, the UE can notify the base station including a lot of information.

[0137] As another example, the UE may use RRC Reconfiguration Complete for the notification. In this way, the UE can notify the base station including a lot of information.

[0138] As another example, new RRC signaling may be provided. For example, signaling such as RRC Reconfiguration Request may be provided and used, or signaling such as Paging Collision Notification may be provided and used.

[0139] As another example regarding the notification from the UE to the base station, MAC signaling may be used. In this way, for example, the UE can quickly notify the paging collision. As another example, L1 / L2 signaling may be used. In this way, for example, the UE can more quickly notify the paging collision.

[0140] The UE may include in the notification information regarding the presence or absence of a paging collision. The information may be, for example, an identifier of the presence or absence of a paging collision. In this way, for example, the UE can notify the paging collision with a small amount of signaling.

[0141] The UE may include in the notification information used for paging collision avoidance. Examples of the information used for paging collision avoidance are disclosed as follows (1) to (10).

[0142] (1) Information regarding the identifier of another NW.

[0143] (2) Information regarding the paging timing of another NW.

[0144] (3) Information regarding the numerology in another NW.

[0145] (4) Information regarding the frame timing in another NW.

[0146] (5) Information used for deriving paging timing in other NWs.

[0147] (6) Information regarding the beam used for communication with the destination NW.

[0148] (7) Information regarding the synchronization signal of other NWs.

[0149] (8) Information regarding the radio access technology (RAT) of other NWs.

[0150] (9) Information regarding the multi-SIM operation of the own UE.

[0151] (10) Combinations of the foregoing (1) to (9).

[0152] The information in the foregoing (1) may be, for example, the PLMN-ID of the other NW, or may include the NPN-ID disclosed in Non-Patent Document 23 (TR23.734), or may include the CAG-ID. As a result, for example, the base station can identify the NWs for which paging collisions should be avoided, and as a result, the complexity of the avoidance process can be avoided.

[0153] As another example regarding the information in the foregoing (1), an identifier that uniquely identifies the UE may be used. The identifier may be, for example, a 5G-GUTI (5G Globally Unique Temporary Identifier). The base station may extract the PLMN-ID of the other NW from the 5G-GUTI. As a result, for example, the base station can simultaneously acquire the identifier of the other NW and the identifier of the UE. As a result, the base station can acquire the information used for deriving paging timing in other NWs with less signaling.

[0154] The information in the foregoing (2) may be, for example, a PF (Paging Frame) in another NW, a PO (Paging Occasion), a PDCCH monitoring occasion used for paging reception, or a combination of a plurality of the foregoing. This makes it possible to reduce the processing amount in paging collision avoidance by a base station, for example.

[0155] As another example, the information in the foregoing (2) may include information regarding the time of paging timing in another NW. The information regarding the time may include, for example, the time at the start point of the paging timing, the time regarding the end point of the paging timing, the information regarding the duration of the paging timing, or a plurality of the foregoing information. The paging timing may be a PF (Paging Frame) in another NW, a PO (Paging Occasion), a PDCCH monitoring occasion used for paging reception, or a combination of a plurality of the foregoing. This makes it possible to reduce the processing amount in paging collision avoidance by a base station, for example.

[0156] The information in the foregoing (3) may be, for example, a subcarrier spacing, a slot length, or a symbol length used by a UE in paging reception from another NW, or a parameter μ disclosed in Section 4.2 of Non-Patent Document 13 (TS38.211). This makes it possible to improve the reliability in paging collision avoidance by a base station, for example.

[0157] The information in (4) above may be provided, for example, in terms of the difference in frame timing between the destination base station and the base stations of other NWs in units of SFN, subframe, slot, symbol, or the minimum unit on the communication system (e.g., Ts unit), or a combination thereof. The slot mentioned above may be a slot in the destination base station or a slot in other NWs. This makes it possible to reduce the processing amount, for example, in paging collision avoidance by the base station.

[0158] As another example, the information in (4) above may be the time at a predetermined point in time in other NWs, for example, the time at the boundary of a predetermined SFN. The boundary may be the start of the SFN or the end of the SFN. As another example, it may be the time at a predetermined subframe boundary, the time at a predetermined slot boundary, or the time at a predetermined symbol boundary. The UE may obtain the information by cell search for the other NW or from the notification information from the other NW. This makes it possible to reduce the processing amount required for the notification of the UE, for example.

[0159] The information in (5) above may include, for example, the identifier of the UE in other NWs or parameters used for determining paging timing in other NWs. The parameters may include part or all of the notification information from the base station of the NW, for example, the PCCH configuration information (PCCH-Config) disclosed in Non-Patent Document 24 (TS38.331). This makes it possible to reduce the processing amount required in the notification from the UE, for example.

[0160] The aforementioned identifier for the information in (5) above may be, for example, the UE_ID disclosed in Section 7.1 of Non-Patent Document 25 (TS38.304), or it may be the 5G-S-TMSI (5G S-Temporary Mobile Subscription Identifier), 5G-TMSI (5G Temporary Mobile Subscription Identifier), or 5G-GUTI disclosed in Non-Patent Document 22 (TS23.501).

[0161] The aforementioned parameter for the information in (5) above may include the DRX (Discontinuous Reception) cycle (T) of the UE disclosed in Non-Patent Document 25 (TS38.304), or may include the total number (N) of paging frames in the cycle, or may include the number (Ns) of paging occasions in PF, or may include the offset (PF_offset) used in PF determination, or may include the first PDCCH monitoring occasion (first-PDCCH-MonitoringOccasionOfPO) in PO.

[0162] The information in (6) above may be information regarding the beam used by the UE for reception from the target base station. The beam may be information regarding the beam used by the UE for reception of the SS block from the base station, or may be information regarding the beam used by the UE for reception of the notification information from the base station, such as SIB1 or RMSI (Remaining Minimum System Information). The base station may use the information in (6) above to change the paging timing in the beam where the UE is located. The base station may also change the notification information in the beam. As a result, for example, the base station can flexibly change the paging timing.

[0163] The information in (7) above may be, for example, information regarding the period of the SS burst, or may be the SS block transmission duration in one period of the SS burst. The base station may use the information in (7) above to set the paging timing by, for example, avoiding the periods of a plurality of SS bursts transmitted from base stations of other NWs, or may set the paging timing by avoiding the SS block transmission duration. The UE may use the information to receive the synchronization signals of base stations of other NWs. The UE may be assumed to receive paging after receiving the synchronization signals. This can prevent, for example, timing deviation in the UE's paging reception.

[0164] The information in (8) above may be, for example, information indicating that the base station of another NW is an NR base station, or may be information indicating that it is an LTE base station. The base station may use the information for changing the paging timing. For example, when the base station of another NW is an LTE base station, for example, when the paging timing in the LTE base station is fixed, the base station may change the period of the paging timing. This can reduce, for example, the possibility of avoidance failure of paging collisions in the communication system.

[0165] The information in (9) above may be, for example, information indicating whether the own UE is a multi-SIM equipped UE, or may be information regarding the operation using multiple SIMs. The information regarding the operation using multiple SIMs may include, for example, the number of transmitters and / or receivers in the own UE, the number of NWs to which the own UE can be connected, or the number of RRCs that the own UE can hold. The information regarding the operation using multiple SIMs may be information regarding the combination of RRC states in the own UE, for example, information indicating whether it is possible to be in the RRC_CONNECTED state simultaneously for a plurality of base stations of a plurality of NWs. The UE may include the information in, for example, the UE capability and notify the base station. The base station may use the information for data transmission and reception with the UE. This can improve, for example, the efficiency in the communication system.

[0166] The base station may change the paging timing using the notification from the UE. For example, the base station may change the parameters used for determining the paging timing. The parameters may be, for example, the aforementioned parameters related to the information in (5) above. The base station may notify the subordinate UEs of the changed parameters. For example, the base station may include the changed parameters in SIB1 and notify them. The UE may change the timing for receiving paging (hereinafter sometimes referred to as the paging reception timing) using the notification.

[0167] The UE may receive paging from the base station that is the notification destination of the information with higher priority than paging from base stations of other NWs. For example, until the UE receives the changed paging parameters from the base station, the UE may receive the prioritized paging. As a result, for example, the UE can quickly obtain the changed paging parameters.

[0168] The base station may change the parameters for each beam. The notification information from the base station may be different for each beam. As a result, for example, the flexibility of parameter setting in the communication system can be improved.

[0169] As another example, the base station may change the parameters for each UE individually. The base station may notify each UE of the changed parameters individually. The base station may include the changed parameters in RRC signaling, for example, RRC reconfiguration (RRCReconfiguration), and notify each UE individually. The UE may change the paging reception timing using the individual notification. As a result, for example, in the communication system, the complexity of the process related to changing the paging timing can be avoided.

[0170] As another example, the base station may set or change the parameters collectively for a plurality of UEs. For example, the base station may perform the setting and / or change of the parameters collectively for a plurality of multi-SIM equipped UEs. For example, the aforementioned plurality of multi-SIM equipped UEs may be all the multi-SIM equipped UEs under the coverage of the base station. For example, for the aforementioned plurality of multi-SIM equipped UEs, the NW connection destinations other than the base station may be the same or different. The plurality of multi-SIM equipped UEs may be treated as a UE group. The base station performs the setting and / or change of the parameters for the UE group.

[0171] The base station may notify the parameters set and / or changed collectively for the plurality of UEs to the plurality of UEs collectively. For example, RRC signaling may be used for the notification. A specific UE-ID, for example, a multicast UE-ID, may be provided for the collective notification. The plurality of UEs may set and / or change the parameters using the collective notification. This can reduce, for example, the signaling amount between the base station and the plurality of UEs.

[0172] The aforementioned collective notification from the base station to the plurality of UEs may be performed in other RRC signaling. This can further reduce, for example, the signaling amount between the base station and the plurality of UEs.

[0173] The UE may notify other NW base stations of the changed parameter notified by the base station. The UE may include information regarding the UE identifier in the notification to the base stations of the other NW. The identifier may be an identifier assigned in the NW of the base station that changed the parameter. The base stations of the other NW may or may not change the paging timing in the other NW using the parameter. As a result, for example, the paging timing in the other NW can be changed while avoiding the notified parameter. Consequently, it is possible to prevent paging collisions after the paging timing is changed.

[0174] Figures 16 and 17 are sequence diagrams showing a first example of the operation in which a multi-SIM UE detects a paging collision and notifies the base station. Figures 16 and 17 are connected at the position of the boundary line BL1617. In Figures 16 and 17, the UE is connected to two NWs (NW#1, NW#2), and is connected to gNB#1 under NW#1 and gNB#2 under NW#2. In Figures 16 and 17, AMF#1 and AMF#2 exist under NW#1 and NW#2, respectively. In the example shown in Figures 16 and 17, the UE is in the RRC_IDLE state with respect to both gNB#1 and gNB#2. Figures 16 and 17 show an example in which the UE notifies gNB#1 of a paging collision.

[0175] In step ST1601 shown in Figure 16, gNB#1 transmits an SS block to the UE. In step ST1602, gNB#2 transmits an SS block to the UE. In step ST1603, the UE acquires the SFN timings of gNB#1 and gNB#2 transmitted in steps ST1601 and ST1602 described above, and derives the difference in the SFN timings of both gNBs.

[0176] In step ST1606 shown in FIG. 16, gNB#1 notifies the UE of system information. The system information notified in step ST1606 includes parameters related to paging in gNB#1. In step ST1607, gNB#2 notifies the UE of system information. The system information notified in step ST1607 includes parameters related to paging in gNB#2. The parameters notified in steps ST1606 and ST1607 may be the same type of parameters as those included in the information disclosed as the information used for paging collision avoidance in the aforementioned (5). In step ST1608, the UE obtains the paging timings in gNB#1 and gNB#2 by using the information obtained in the aforementioned steps ST1606 and ST1607.

[0177] Step ST1611 shown in FIG. 16 represents the paging timing for the UE from gNB#1. Step ST1612 represents the paging timing for the UE from gNB#2. FIG. 16 shows a case where the paging timings of gNB#1 and gNB#2 collide with each other.

[0178] In step ST1615 shown in FIG. 16, the UE determines whether there is a paging collision from gNB#1 and gNB#2. For this determination, the difference in frame timings obtained in step ST1603 and the paging timings obtained in step ST1608 may be used. If the UE determines that no paging collision has occurred, it may not perform the processing after step ST1621 and may return to the processing of obtaining system information in steps ST1606 and ST1607. If the UE determines that a paging collision has occurred, it performs the processing after step ST1621.

[0179] Steps ST1621 to ST1629 shown in FIG. 16 relate to the process in which the UE notifies the gNB#1 of a paging collision. In step ST1621, the UE transmits a PRACH to the gNB#1. In step ST1623, the gNB#1 transmits a Random Access Response (RAR) to the UE.

[0180] In step ST1625 shown in FIG. 16, the UE requests the gNB#1 to initiate RRC. For this request, RRC signaling, for example, the RRC Setup Request in Non-Patent Document 24 (TS38.331) may be used. In step ST1627, the gNB#1 instructs the UE to initiate RRC. For this instruction, RRC signaling, for example, the RRC Setup in Non-Patent Document 24 (TS38.331) may be used.

[0181] In step ST1629 shown in FIG. 16, the UE notifies the gNB#1 of the completion of RRC initiation. For this notification, RRC signaling, for example, the RRC Setup Complete in Non-Patent Document 24 (TS38.331) may be used. The UE may include information regarding the paging collision in the notification in step ST1629. This information may include, for example, information regarding the presence or absence of a paging collision, or may include the aforementioned information (1) to (10) disclosed as examples of information used for paging collision avoidance.

[0182] In step ST1631 shown in FIG. 17, gNB#1 changes the paging timing. In step ST1633, gNB#1 notifies the UE of system information. The notification may include parameters related to the changed paging timing. In step ST1635, the UE acquires the paging parameters notified in step ST1633 above, and acquires the paging timing of gNB#1 using the parameters. The UE changes the paging reception timing of gNB#1 according to the acquired paging timing.

[0183] The UE receives the paging of gNB#1 at the changed paging reception timing of gNB#1. As a result, the UE can receive paging from gNB#1 and paging from gNB#2.

[0184] For example, the UE receives paging from gNB#1, and if there is no paging, switches the reception to gNB#2 by the paging timing of gNB#2 and receives the paging of gNB#2. Also, the UE receives paging from gNB#2, and if there is no paging, switches the reception to gNB#1 by the paging timing of gNB#1 and receives the paging of gNB#1. For example, the UE receives paging from gNB#1, and if there is paging, may perform processing according to the received paging.

[0185] The base station may request the AMF to change the identifier of the UE. The base station may make such a request, for example, when paging collision avoidance is impossible only by changing parameters (e.g., PCCH configuration information (PCCH-Config)) used for determining paging timing in the above-mentioned (5). When paging collision is possible by changing such parameters, the base station may not make such a request to the AMF. This can prevent unnecessary changes to the identifier, for example, when paging collision can be avoided only by changing the PCCH configuration information. The request may include one or more UE identifiers to be changed. For example, signaling in the N2 interface may be used for such a request. New signaling, such as signaling for an N2 UE configuration update request, may be provided and used. The identifier of the UE may be, for example, the UE_ID disclosed in Section 7.1 of Non-Patent Document 25 (TS38.304), or the 5S-TMSI (5G S-Temporary Mobile Subscription Identifier), 5G-TMSI (5G Temporary Mobile Subscription Identifier), or 5G-GUTI disclosed in Non-Patent Document 22 (TS23.501). The AMF may change the identifier of the UE using such signaling.

[0186] The base station may notify the AMF of information used for paging collision avoidance. The base station may include the information in the request for the UE identifier and notify it. The information may include the information in (1) to (10) above. The base station may convert the information in (1) to (10) above notified from the UE into signaling on the N2 interface and notify it. The information may further include information about its own NW. The information about its own NW may be the information in (1) to (10) above with other NWs replaced by its own NW. The AMF may change the UE identifier using the information about its own NW. This makes it possible to prevent paging collisions in the changed UE identifier, for example.

[0187] The AMF may notify the UE of the changed identifier. For the notification, NAS signaling, for example, the configuration update command (CONFIGURATION UPDATE COMMAND) disclosed in Non-Patent Document 27 (TS24.501) may be used. The identifier may be, for example, the 5G-S-TMSI (5G S-Temporary Mobile Subscription Identifier) disclosed in Non-Patent Document 22 (TS23.501). The UE may update its own UE-ID using the notification.

[0188] The UE may notify the AMF of the completion of the update of its own UE identifier. For the notification, NAS signaling, for example, the configuration update complete (CONFIGURATION UPDATE COMPLETE) disclosed in Non-Patent Document 27 (TS24.501) may be used.

[0189] The AMF may notify the base station of the changed identifier. Signaling on the N2 interface may be used for the notification. The base station may change the paging timing of the UE using the notification. For example, the base station may change the parameters used for determining the paging timing using the changed identifier of the UE. This can improve the flexibility of changing the paging timing in the UE, for example. The notification of the changed parameters from the base station to the UE may be the same as described above.

[0190] Figures 18 and 19 are sequence diagrams showing a second example of the operation in which a multi-SIM UE detects a paging collision and notifies the base station, and the base station requests the identifier of the UE from the AMF. Figures 18 and 19 are connected at the position of the boundary line BL1819. In Figures 18 and 19, the UE is connected to two NWs (NW#1, NW#2), and is connected to gNB#1 under NW#1 and gNB#2 under NW#2. In Figures 18 and 19, AMF#1 and AMF#2 exist under NW#1 and NW#2, respectively. In the example shown in Figures 18 and 19, the UE is in the RRC_IDLE state with respect to both gNB#1 and gNB#2. Figures 18 and 19 show an example in which the UE notifies gNB#1 of a paging collision, and gNB#1 requests a change in the identifier of the UE from AMF#1. In Figures 18 and 19, the same step numbers are assigned to the same processes as in Figures 16 and 17, and common descriptions are omitted.

[0191] Steps ST1601 to ST1629 shown in Figure 18 are the same as those in Figure 16.

[0192] In step ST1730 shown in FIG. 19, gNB#1 requests AMF#1 to change the identifier of the UE. For this request, for example, signaling on the N2 interface may be used. New signaling, for example, signaling of N2 UE configuration update request may be provided and used. In step ST1732, AMF#1 changes the identifier of the UE. The identifier may be, for example, 5G-S-TMSI.

[0193] In step ST1734 shown in FIG. 19, AMF#1 instructs the UE to update the identifier of the UE. For this instruction, NAS signaling, for example, CONFIGURATION UPDATE COMMAND disclosed in Non-Patent Document 27 (TS24.501) may be used. The instruction may include, for example, the updated 5G-S-TMSI of the UE. In step ST1736, the UE updates its own UE-ID using this instruction.

[0194] In step ST1738 shown in FIG. 19, the UE notifies the AMF of the completion of the update of its own identifier. For this notification, NAS signaling, for example, CONFIGURATION UPDATE COMPLETE disclosed in Non-Patent Document 27 (TS24.501) may be used.

[0195] In step ST1740 shown in FIG. 19, AMF notifies the base station of the changed identifier. For this notification, signaling on the N2 interface may be used. The notification may include the changed identifier. The identifier may be 5G-S-TMSI, or UE-ID, or 5G-GUTI. In step ST1631, gNB#1 may change the parameters related to paging timing using the changed identifier notified in step ST1740 above.

[0196] Steps ST1633 and ST1635 shown in FIG. 19 are the same as those in FIG. 17.

[0197] The notification of the changed identifier from the AMF to the base station may be performed before the UE notifies the AMF of the completion of the update of its own identifier. This can improve, for example, the flexibility of paging timing change in the UE, and enable the base station to quickly determine the parameters related to paging timing.

[0198] FIGS. 20 and 21 are sequence diagrams showing a third example of the operation in which a multi-SIM UE detects a paging collision and notifies the base station, and the base station requests the identifier of the UE from the AMF. FIGS. 20 and 21 are connected at the position of the boundary line BL2021. In FIGS. 20 and 21, the UE is connected to two NWs (NW#1, NW#2), and is connected to gNB#1 under NW#1 and gNB#2 under NW#2. In FIGS. 20 and 21, AMF#1 and AMF#2 exist under NW#1 and NW#2, respectively. In the example shown in FIGS. 20 and 21, the UE is in the RRC_IDLE state with respect to both gNB#1 and gNB#2. FIGS. 20 and 21 show an example in which the UE notifies gNB#1 of a paging collision, and gNB#1 requests the change of the UE's identifier from AMF#1. In FIGS. 20 and 21, the same step numbers are assigned to the same processes as in FIGS. 16 to 19, and the common descriptions are omitted.

[0199] Steps ST1601 to ST1629 shown in FIG. 20 are the same as those in FIG. 16.

[0200] Steps ST1730 to ST1736 shown in FIG. 21 are the same as those in FIG. 19.

[0201] In step ST1840 shown in FIG. 21, the AMF notifies the base station of the changed identifier. The notification may be the same as step ST1740 in FIG. 19.

[0202] Steps ST1631 to ST1635 shown in FIG. 21 are the same as those in FIG. 17.

[0203] Step ST1738 shown in FIG. 21 is similar to that in FIG. 19.

[0204] In FIGS. 20 and 21, the case where the notification of the completion of the identifier update of the own UE from the UE to the AMF is performed after the paging timing change in the own UE is shown. As another example, the UE may notify the completion of the identifier update of the own UE before the paging timing change. For example, the UE may perform step ST1738 after the UE-ID change shown in step ST1736. Thereby, for example, the waiting time in the AMF for the notification can be shortened, and as a result, the efficiency of the operation in the AMF can be improved.

[0205] As another example regarding the notification from the UE to the NW, the UE may perform the notification to the AMF. For example, the UE may perform the notification to the AMF connected to the base station with the earlier PRACH transmission timing among the base stations of the plurality of NWs. Thereby, for example, the UE can quickly connect to any one of the plurality of NWs, and as a result, paging collisions can be quickly avoided.

[0206] The UE may send the notification using NAS signaling. The UE may include the NAS signaling in RRC signaling, for example, RRC Setup Complete. The gNB may extract the NAS signaling from the RRC signaling. The gNB may transfer the NAS signaling to the AMF. For the transfer, signaling on the N2 interface, for example, INITIAL UE TRANSFER disclosed in Non-Patent Document 26 (TS38.413), may be used. For the transfer, new signaling may be provided. As a result, for example, the UE can notify information regarding paging collision in the first NAS signaling after RRC setup. Consequently, the AMF can quickly obtain information regarding paging collision.

[0207] As another example, new NAS signaling may be provided. For example, signaling for a UE configuration update request from the UE to the AMF may be provided. The UE may send the notification to the AMF using the newly provided NAS signaling.

[0208] The UE may send the notification to the AMF of one NW. As a result, for example, in a communication system, paging collision avoidance can be performed with a small amount of signaling. As another example, the UE may send the notification to the AMFs of multiple NWs. As a result, for example, in a communication system, the flexibility of paging timing change can be improved.

[0209] The UE may notify the AMF of the information used for paging collision avoidance. The UE may include this information in the notification. This information may include the information in (1) to (10) above. This information may further include information about its own NW. The information about its own NW may be the information in (1) to (10) above with other NWs replaced by its own NW. As a result, for example, the AMF can obtain without shortage the parameters necessary for deriving the paging timing of the UE. Consequently, paging collision in the UE can be reliably avoided. The AMF may change the identifier of the UE using the information about its own NW. As a result, for example, paging collision in the identifier of the UE after the change can be prevented.

[0210] The AMF may change the identifier of the UE using this signaling. The AMF may notify the UE of the identifier after the change. For this notification, NAS signaling, for example, the configuration update command disclosed in Non-Patent Document 27 (TS24.501) may be used. The identifier may be, for example, the 5G-S-TMSI (5G S-Temporary Mobile Subscription Identifier) disclosed in Non-Patent Document 22 (TS23.501). The UE may update its own UE-ID using this notification.

[0211] The UE may notify the AMF of the completion of the update of its own identifier. For this notification, NAS signaling, for example, the configuration update complete disclosed in Non-Patent Document 27 (TS24.501) may be used.

[0212] The AMF may notify the base station of the changed identifier. Signaling on the N2 interface may be used for the notification. The base station may update the UE-ID using the notification. The base station may change the paging timing using the notification. The base station may or may not change the parameters used for determining the paging timing using the changed identifier of the UE. This can improve, for example, the flexibility of changing the paging timing in the UE. The notification of the changed parameters from the base station to the UE may be the same as described above.

[0213] The UE may notify the other NW's AMF of the changed parameters notified by the AMF. The UE may include information regarding the identifier of the UE in the notification to the other NW's AMF. The identifier may be the identifier assigned in the NW of the AMF that changed the parameters. The other NW's AMF may or may not change the paging timing in the other NW using the parameters. This can change, for example, the paging timing in the other NW while avoiding the notified parameters. As a result, it is possible to prevent paging collisions after the paging timing is changed.

[0214] Figures 22 and 23 are sequence diagrams showing an example of an operation in which a multi-SIM UE detects a paging collision and notifies the AMF. Figures 22 and 23 are connected at the position of the boundary line BL2223. In Figures 22 and 23, the UE is connected to two NWs (NW#1, NW#2), and is connected to gNB#1 under NW#1 and gNB#2 under NW#2. In Figures 22 and 23, AMF#1 and AMF#2 exist under NW#1 and NW#2, respectively. In the example shown in Figures 22 and 23, the UE is in the RRC_IDLE state with respect to both gNB#1 and gNB#2. Figures 22 and 23 show an example in which the UE notifies AMF#1 of a paging collision via gNB#1. In Figures 22 and 23, the same step numbers are assigned to the same processes as in Figures 16 to 19, and common explanations are omitted.

[0215] Steps ST1601 to ST1627 shown in Figure 22 are the same as those in Figure 16.

[0216] In step ST1929 shown in Figure 22, the UE notifies gNB#1 of the completion of RRC startup. For this notification, RRC signaling, for example, RRC startup completion (RRCSetupComplete) of Non-Patent Document 24 (TS38.331) may be used. The UE may include NAS signaling in the notification in step ST1629. The UE may include information regarding paging collision in the NAS signaling. The information may include, for example, information regarding the presence or absence of a paging collision, or the aforementioned information (1) to (10) disclosed as examples of information used for paging collision avoidance.

[0217] In step ST1931 shown in FIG. 23, gNB#1 transfers the NAS signaling received from the UE to AMF#1. For this transfer, signaling on the N2 interface, for example, INITIAL UE TRANSFER disclosed in Non-Patent Document 26 (TS38.413), may be used. For this transfer, new signaling may be provided. By receiving the signaling in step ST1931, AMF#1 recognizes the occurrence of a paging collision.

[0218] Steps ST1732 to ST1740 shown in FIG. 23 are the same as those in FIG. 19.

[0219] In FIG. 23, the case where gNB#1 does not change the parameters related to paging timing is shown, but gNB#1 may change the parameters. In this case, steps ST1631 to ST1635 shown in FIG. 19 may be performed. This can improve the flexibility of paging timing change in a communication system, for example.

[0220] Information regarding paging collisions may be acquired by other base stations. The other base station may be, for example, the base station to which the UE is handed over (hereinafter sometimes referred to as the target base station). The base station from which the handover occurs (hereinafter sometimes referred to as the source base station) may notify the target base station of information regarding paging collisions. The information may be, for example, the information in (1) to (10) described above. This can prevent paging collisions even after the UE has been handed over, for example.

[0221] The source base station may perform the notification using signaling on the base station interface (for example, the Xn interface), for example, the signaling of HANDOVER REQUEST disclosed in Non-Patent Document 28 (TS38.423). This can enable the source base station to quickly notify the target base station of the information, for example.

[0222] As another example, the UE may notify the target base station of the information. The UE may perform the notification using the aforementioned RRC signaling, for example, the signaling of RRC reconfiguration completion. This can reduce the signaling amount in the base station interface, for example.

[0223] The UE may notify the base station with the earliest PRACH transmission timing among the base stations of the NW to which the UE is connected of the information regarding the paging collision. This can enable the UE to quickly notify the NW of the paging collision, for example.

[0224] As another example, the UE may set a primary NW or a secondary NW. The UE may perform the notification to the base station and / or AMF of the primary NW or to the base station and / or AMF of the secondary NW. This can avoid the complexity of the process for notifying the information regarding the paging collision in the design of the communication system.

[0225] A person may set the primary NW and / or the secondary NW for the UE. For example, the primary NW and the secondary NW are set according to the person's preference. This can enable paging collision avoidance to be implemented for the NW preferred by the person. The UE may pre-store the setting of the primary NW and / or the secondary NW. The UE can use the setting of the primary NW and / or the secondary NW at any time.

[0226] The UE may process the paging from multiple NWs in the order of arrival. This can avoid the complexity of the UE design, for example.

[0227] As another example, the UE may process paging for a later arrival earlier than paging for an earlier arrival. The above-described operation may be performed, for example, when the UE receives high-priority paging for a later arrival during the processing of paging for an earlier arrival. The base station may include information indicating the priority in the paging and notify the UE. The UE may use the information to determine whether to process the paging for a later arrival. As a result, for example, it becomes possible to quickly start high-priority communication, and as a result, QoS in the communication system can be ensured.

[0228] Another solution is disclosed. The UE may receive paging from a plurality of NWs in a time-division manner. Paging from a plurality of NWs may be transmitted in a time-division manner. The UE may receive paging from each NW using the time-division multiplexed paging timing. As a result, for example, power consumption in the UE can be reduced.

[0229] The UE may determine a method for time-division multiplexing paging. The UE may notify the base station that it receives paging in a time-division multiplexed manner. The UE may send the notification to the base station of one NW, to the base stations of a plurality of NWs, or to the base stations of all the NWs to which it is connected. The method for notifying the base station from the UE may be the same as the method for notifying information regarding paging collision from the UE to the base station in the above-described solution. The base station may include paging information for the UE only at the paging timing received by the UE using the notification. As a result, for example, power consumption at the base station can be reduced, and the number of UEs that can be accommodated in paging can be increased.

[0230] The notification from the UE to the base station may include information regarding the paging timing after time division multiplexing. This information may include, for example, the information of (2) and / or (5) disclosed as information regarding paging collision. As the information of (5) above, for example, information regarding the paging period may be used. As the information regarding the paging period, for example, the DRX (Discontinuous Reception) period (T) of the UE disclosed in Non-Patent Document 25 (TS38.304) may be used, or the total number (N) of paging frames in this period may be used.

[0231] As another example, this information may include information regarding the paging timing that cannot be allocated by time division multiplexing. This paging timing may be a PF (Paging Frame) that cannot be allocated by time division multiplexing, or a PO (Paging Occasion), or a PDCCH monitoring occasion used for paging reception, or a combination of multiple of the above.

[0232] As another example, the UE may determine the method of time division multiplexing for paging. The UE may not notify the base station that it will receive paging by time division multiplexing. The UE may receive paging from each NW using the paging time division multiplexing method determined by the UE itself. This can, for example, avoid the complexity of the design of the communication system.

[0233] As another example, the base station may determine a time division multiplexing method for paging. The base station may be, for example, a base station of the primary NW. The UE may request time division multiplexing of paging from the base station. The determination by the base station may be triggered by the request from the UE, or may be made without the request from the UE. The base station may notify other NW base stations of the time division multiplexing information for paging. The notification may be made via the UE. The base station may make the notification using RRC signaling, or using MAC signaling, or using L1 / L2 signaling. The UE may make the notification to other NW base stations using RRC signaling, or using MAC signaling, or using L1 / L2 signaling. As a result, for example, it becomes unnecessary to determine the time division multiplexing method for paging in the UE, and thus the design complexity can be avoided.

[0234] The base station that determines the time division multiplexing method for paging may be a base station of one NW, or may be base stations of multiple NWs. The UE may send the request to a base station of one NW, or may send the request to base stations of multiple NWs. By having multiple NW base stations determine the method, for example, the operation of determining the time division multiplexing method for paging in the communication system can be started quickly.

[0235] FIG. 24 is a diagram showing a first example of time division multiplexing of paging. In FIG. 24, the UE is connected to two NWs (NW#1, NW#2). In FIG. 24, the solid and dashed rectangles indicate the paging timings before time division multiplexing in each NW. In FIG. 24, the UE may not receive paging from the NW at the timing of the rectangle indicated by the dashed line as a result of time division multiplexing. In the example shown in FIG. 24, paging from NW#1 and paging from NW#2 are transmitted at the same period. In the example shown in FIG. 24, the UE may receive paging from NW#1 and NW#2 alternately.

[0236] Figure 25 shows a second example of time-division multiplexing for paging. In Figure 25, the UE is connected to two NWs (NW#1 and NW#2). In Figure 25, the solid and dashed rectangles indicate the paging timings before time-division multiplexing in each NW. In Figure 25, the UE may not receive paging from the NW at the timing of the rectangle shown by the dashed line as a result of time-division multiplexing. In the example shown in Figure 25, paging from NW#1 is transmitted at a larger period than paging from NW#2. In the example shown in Figure 25, the UE may receive paging from NW#1 when paging from NW#1 and NW#2 overlaps.

[0237] Other solutions are disclosed. The base station may detect a paging collision. The base station may be a base station of one NW or a base station of a plurality of NWs to which the UE is connected. The UE may notify the base station of its identifier in other NWs. The notification may include information regarding the cell to which the UE is connected in other NWs, for example, PCI. The base station may acquire information regarding paging in the other NWs. The acquisition of the information at the base station may be performed by acquiring notification information from the base station of the other NW or by notification from the UE to the base station. This makes it possible to reduce, for example, the processing amount related to paging collisions in the UE.

[0238] The method disclosed in Embodiment 1 may be applied to paging collisions between an NR base station and an LTE base station. The LTE base station and / or the NW connected to the LTE base station may only change the identifier of the UE. This can avoid, for example, the complexity of the design in the communication system. As another example, the LTE base station and / or the NW connected to the LTE base station may be able to change other parameters related to paging as well. This can improve, for example, the flexibility of changing paging timing. The notification from the UE to the NR base station and / or the AMF, as well as the notification from the UE to the LTE base station and / or the MME, may be the same as the aforementioned solution. The notification from the UE to the AMF connected to the NR base station, as well as the notification from the UE to the MME connected to the LTE base station, may also be the same as the aforementioned solution. This can avoid, for example, paging collisions between the NR base station and the LTE base station for the UE.

[0239] The UE may notify the NR base station of the paging collision. This can, for example, flexibly change the paging timing of the UE in the communication system.

[0240] As another example, the UE may notify the LTE base station and / or the MME of the paging collision. This can, for example, reduce the signaling amount between the UE and the NR base station, and as a result, ensure the communication speed in the communication system.

[0241] The method disclosed in Embodiment 1 may be applied to paging collisions between LTE base stations. The notification from the UE to the LTE base station and / or the MME may be the same as the aforementioned solution. This enables, for example, avoidance of paging collisions between LTE base stations. The LTE base station and / or the NW to which the LTE base station is connected may only change the identifier of the UE. This enables, for example, avoidance of the complexity of design in the communication system. As another example, the LTE base station and / or the NW to which the LTE base station is connected may be able to change including other parameters related to paging. This enables, for example, improvement in the flexibility of paging timing change.

[0242] The UE may have a plurality of RRCs. For example, when the UE is a multi-SIM equipped UE, it may be allowed to have a plurality of RRCs. For example, the UE may have an RRC for each base station of a plurality of NWs. This facilitates, for example, control between the UE and each base station.

[0243] As another example, the UE may have an RRC for each transceiver. This may be the same even when the number of transmitters and receivers the UE has is different. For example, the UE may have an RRC for each transmitter the UE has, or may have an RRC for each receiver the UE has. The UE may have only the larger number or the smaller number of RRCs out of the number of transmitters and the number of receivers the UE has. This enables, for example, easy control of each transceiver of the UE.

[0244] As another example, the UE may have only one RRC. For example, even if the UE is a multi-SIM UE, it may have only one RRC. The same applies even if the UE has multiple transceivers. The same also applies even if the number of transmitters and receivers the UE has is different. For example, when the UE has only one transmitter, the UE may have only one RRC. For example, when the UE has only one receiver, the UE may have only one RRC. This facilitates, for example, the control between the UE and the base stations of multiple NWs, such as the adjustment of frequency, time, and / or power resources among the base stations of multiple NWs.

[0245] The UE may have multiple RRC states. For example, when the UE itself is a multi-SIM UE, it may be allowed to have multiple RRC states. For example, it may have an RRC for each base station of multiple NWs. The UE may have one RRC state for one RRC, or may have multiple RRC states for one RRC. This enables, for example, the communication system to easily control the connection state with each base station.

[0246] As another example where the UE has multiple RRC states, it may have an RRC state for each transceiver. The same applies even if the number of transmitters and receivers the UE has is different. For example, the UE may have an RRC state for each transmitter it has, or may have an RRC state for each receiver it has. The UE may have RRC states only for the larger number of either the number of transmitters or receivers it has, or may have RRC states only for the smaller number. This enables, for example, the operating status of each transceiver of the UE to be easily controlled.

[0247] The multiple RRC states of a UE may be independent of each other. For example, in the case where a UE has multiple transceivers, the multiple RRC states may be independent of each other. As another example, in the case where a UE has a single transceiver, the multiple RRC states may be independent of each other. This can improve the flexibility in a communication system, for example.

[0248] As another example, the multiple RRC states of a UE may have interdependence. For example, when the RRC state with a base station of one NW transitions to RRC_CONNECTED, the RRC state with a base station of another NW may also transition to RRC_CONNECTED. As another example, when the RRC state with a base station of one NW transitions to RRC_IDLE or RRC_INACTIVE, the RRC state with a base station of another NW may also transition to RRC_IDLE or RRC_INACTIVE. For example, in the case where a UE has a single transceiver, the multiple RRC states may have interdependence. As another example, in the case where a UE has multiple transceivers, the multiple RRC states may have interdependence. This can facilitate the control of RRC states in a communication system, for example.

[0249] A UE may have only one RRC state. This can facilitate the control of the operating status of the UE, for example.

[0250] The method disclosed in Embodiment 1 may be applied to the reception of SS blocks and / or system information. For example, a UE may receive SS blocks from base stations of multiple NWs in a time-division manner. As another example, a UE may request a base station of one NW to avoid a collision in system information transmission timing. The base station may use this request to change the system information transmission timing. This can avoid transmission timing collisions for SS blocks and / or system information, for example.

[0251] According to Embodiment 1, it is possible to avoid duplication of paging between NWs.

[0252] Modification Example 1 of Embodiment 1. The same method as in Embodiment 1 may be applied to a communication system in which a plurality of NWs share the same base station.

[0253] FIG. 26 is an architecture diagram showing an example of the connection between a multi-SIM UE and a plurality of NWs in a communication system in which a plurality of NWs share the same base station. In FIG. 26, PLMN#1 and PLMN#2 share the same base station 2201. In FIG. 26, the multi-SIM UE is connected in parallel to PLMN#1 and PLMN#2.

[0254] In the example shown in FIG. 26, UE1400 is connected to gNB2201. gNB2201 is connected to AMF1402 and UPF1403 in PLMN#1. SMF1404 in PLMN#1 is connected to AMF1402 and UPF1403. gNB2201 is connected to AMF1412 and UPF1413 in PLMN#2. SMF1414 in PLMN#2 is connected to AMF1412 and UPF1413.

[0255] In the example shown in FIG. 26, the case where UE1400 is connected to two PLMNs is shown, but UE1400 may be connected to three or more PLMNs. Also, one or more of the two NWs to which UE1400 is connected may be NPNs. The same applies even when UE1400 is connected to three or more NWs.

[0256] The UE may notify the base station of paging timing collisions between multiple NWs. The notification may be the same as the notification disclosed in Embodiment 1. As another example, the UE may notify the AMF of paging timing collisions between multiple NWs. The AMF may be the AMF of one NW or the AMFs of multiple NWs. The notification from the UE to the AMF may be the same as the notification disclosed in Embodiment 1. This enables, for example, avoidance of paging collisions even in a communication system where multiple NWs share a base station.

[0257] Other solutions are disclosed. The base station may detect paging timing collisions. The base station may change the paging parameters in each NW. The base station may inform the UE of the changed parameters or notify them individually.

[0258] The UE may notify the base station of the identifiers of the UE assigned by each NW. This enables, for example, the base station to identify that the identifiers of the UE in each NW belong to the same UE. As a result, the base station can execute parameter changes for paging collision avoidance. The identifier may be the UE_ID or the 5G-S-TMSI. This can reduce, for example, the signaling volume in the notification from the UE to the base station. As another example, the identifier may be the 5G-TMSI. This enables, for example, the UE to notify the base station of the NW identifier at the same time, and as a result, the identification at the base station can be executed quickly. As another example, the identifier may be the 5G-GUTI.

[0259] As another example, the base station may obtain the identifier of the UE assigned by each NW by using NAS signaling between the UE and the AMF of each NW. For example, the base station may obtain the identifier of the UE in the NW by using NAS signaling related to the registration of the UE to each NW. The base station may be able to decode the NAS signaling. This can reduce, for example, the signaling between the UE and the base station.

[0260] The base station may request the AMF to change the identifier of the UE. The request may be the same as the request for changing the UE identifier from the base station to the AMF disclosed in Embodiment 1. The AMF may use the request to change the identifier of the UE. The AMF may notify the UE of the change of the UE identifier. The notification may use the NAS signaling disclosed in Embodiment 1, for example, the CONFIGURATION UPDATE COMMAND disclosed in Non-Patent Document 27 (TS24.501).

[0261] The UE may notify the AMF of the completion of the update of its own UE identifier. The notification may use the NAS signaling, for example, the CONFIGURATION UPDATE COMPLETE disclosed in Non-Patent Document 27 (TS24.501), which is the same as in Embodiment 1.

[0262] The AMF may notify the base station of the changed identifier. The notification may use the signaling on the N2 interface, which is the same as in Embodiment 1. The base station may use the notification to change or not change the paging timing of the UE.

[0263] Other solutions are disclosed. The paging may include information about the NW. The information about the NW may be, for example, an identifier indicating a PLMN and / or an NPN. It is preferable that the information indicates which NW the paging information is related to. The information about the NW and the paging information may be associated as paging information. The UE can recognize which NW the received paging information corresponds to.

[0264] The base station may transmit the paging of any one NW. For example, the base station may transmit the paging of the primary NW. The paging includes the aforementioned information about the NW. By doing so, the UE can obtain the paging information of multiple NWs by receiving the paging at the paging timing of one NW.

[0265] The base station may notify the information for identifying the one NW. The information for identifying the one NW may be, for example, an identifier of the NW. The base station may individually notify the UE of the information for identifying the one NW. For example, RRC signaling may be used for the notification. Also, the base station may notify the information about the paging timing of the one NW. Alternatively, the base station may individually notify the UE of the information about the paging timing of the one NW. For example, RRC signaling may be used for the notification. By doing so, the UE can identify the one NW, derive the paging timing of the NW, and receive the paging at the paging timing of the NW.

[0266] By doing so, the UE only needs to receive the paging at the paging timing from one NW, and the complexity of the UE's paging processing can be avoided.

[0267] According to this Modification Example 1, paging collisions can be avoided even in a communication system where multiple NWs share a base station.

[0268] Modification Example 2 of Embodiment 1. In Embodiment 1, a method for avoiding paging collisions between a plurality of NWs was disclosed. In this Modification Example 2, a method for avoiding random access contention is disclosed.

[0269] The UE detects random access collisions between the base stations of a plurality of NWs. Similar to Embodiment 1, the UE may detect the collision using information regarding frame timing between the base stations of a plurality of NWs, or may detect the collision using system information received from the plurality of base stations, for example, system information regarding random access. Both of the above may be combined.

[0270] The UE notifies a base station of one NW of information regarding random access collisions. The base station may be, for example, the base station of the primary NW disclosed in Embodiment 1. The base station may change the random access timing for the UE using the notification from the UE. The random access timing may be, for example, the PRACH transmission timing from the UE, or the timing of the RAR received by the UE. The base station may notify the UE of the changed timing.

[0271] The base station may change the random access preamble. The base station may notify the UE of information regarding the changed preamble. The UE may transmit a PRACH to the base station using the changed preamble. This can prevent, for example, the base stations of other NWs from misidentifying the PRACH from the UE to the base station as a PRACH for their own base stations. Also, the base station can be prevented from misidentifying the PRACH for the base stations of other NWs as a PRACH for its own station.

[0272] The following (1) to (8) are disclosed as information regarding random access processing between the base stations of other NWs notified by the UE to the base station.

[0273] (1) Information regarding the identifiers of the base stations of other NWs.

[0274] (2) Information regarding the PRACH transmission timing to the base stations of other NWs.

[0275] (3) Information regarding the numerology of the base stations of other NWs.

[0276] (4) Information regarding the frame timing of the base stations of other NWs.

[0277] (5) Information regarding the RAR reception timing from the base stations of other NWs.

[0278] (6) Information regarding the beams received from the base stations of other NWs.

[0279] (7) Information regarding the preambles of the PRACH to the base stations of other NWs.

[0280] (8) Combinations of the foregoing (1) to (7).

[0281] The information in the foregoing (1) may be, for example, the base station identifier of a base station that is not performing data transmission and reception (hereinafter sometimes referred to as an inactive base station), or it may be a cell identifier. As a result, for example, a base station that performs data transmission and reception (hereinafter sometimes referred to as an active base station) can grasp the inactive base stations to which the UE should receive synchronization signals, system information, and / or paging. As a result, it is possible to avoid the complexity regarding scheduling by the active base station.

[0282] The information in the foregoing (2) may be information regarding the start timing of the PRACH transmitted by the UE. The information may be an SFN, subframe number, slot number, or symbol number, or it may be a combination of the foregoing. The information may include information regarding the length of the PRACH transmitted by the UE, or it may include information regarding the end timing of the PRACH. As a result, for example, the UE can notify information regarding the PRACH transmitted by the UE itself with a small amount of signaling.

[0283] The information in (2) above may, as another example, include information regarding the time of the PRACH transmitted by the UE. The information regarding time may include, for example, the time at the start point of the PRACH, the time regarding the end point of the PRACH, the information regarding the length of the PRACH, or a plurality of the above-mentioned information. Thereby, for example, the processing amount in random access collision avoidance by the base station can be reduced.

[0284] The information in (3) above may be, for example, the subcarrier spacing, slot length, or symbol length used by the UE in random access processing with a base station of another NW, or may be the parameter μ disclosed in Section 4.2 of Non-Patent Document 13 (TS38.211). Thereby, for example, the reliability in the avoidance processing by the base station can be improved.

[0285] The information in (4) above may be the same as the information in (4) used for paging collision avoidance disclosed in Embodiment 1. The information may be, for example, information regarding the difference in frame timing between the base station and a base station of another NW. Thereby, for example, the processing amount in the avoidance processing by the base station can be reduced. As another example, it may be a predetermined time point in a base station of another NW, for example, the time at the boundary of a predetermined SFN. Thereby, for example, the processing amount required for the UE's notification can be reduced.

[0286] The information in (5) above may include, for example, information regarding the start point of the RAR reception timing, information regarding the end point, or information regarding the length of the RAR reception timing. The information may be in the same format as (2) above, for example. As another example, the information in (5) above may be the ra-ResponseWindow disclosed in Non-Patent Document 24. Thereby, for example, in the UE, it is possible to prevent a collision between the transmission and reception with the base station and the timing of the RAR from a base station of another NW.

[0287] The information in (6) above may be information regarding the beam used by the UE to receive the SS block from the base station of another NW. This information may be, for example, the identifier of the SS block within the SS burst. The base station may use this information to refrain from transmitting and receiving with the UE only at the timing of random access corresponding to the SS block received by the UE. This can improve, for example, the communication rate between the UE and the base station.

[0288] The information in (7) above may include, for example, information regarding the preamble of the PRACH transmitted by the UE to the base station of another NW. The base station may use this information to allocate a preamble different from the preamble for the PRACH transmission to the UE for the PRACH transmission to the base station itself. This can prevent, for example, the base station from misidentifying the PRACH transmitted from the UE to the base station of another NW as the PRACH for the base station itself.

[0289] Another solution is disclosed. The UE may transmit the PRACH to one base station. The UE may not transmit the PRACH to other base stations. The UE may transmit the PRACH to the base station with the earliest start of the PRACH transmission timing. This can enable, for example, the UE to quickly establish a connection. As another example, the UE may transmit the PRACH to the base station for which high-priority communication is to be performed. The UE may determine the base station using the priority information included in the paging disclosed in Embodiment 1, or may determine the base station using the priority information of the uplink communication generated in the UE itself. This can enable, for example, the UE to quickly start high-priority communication, and as a result, ensure the QoS of the communication.

[0290] Another solution is disclosed. The UE may transmit the PRACH to a plurality of base stations. This operation of the UE may be performed, for example, when the UE has a plurality of transceivers. This can enable, for example, the UE to quickly establish connections with a plurality of base stations.

[0291] The UE may distribute the power for each base station using the path loss between the UE and the base station, or may distribute it using the priority of communication with each base station, or may distribute it using both of the above. This can improve the efficiency in the communication system, for example.

[0292] According to this Modification Example 2, it is possible to avoid the collision of the random access timings among a plurality of NWs.

[0293] Embodiment 2. The multi-SIM UE may perform the reception operations of the synchronization signal, the system information, and / or the paging. The UE may perform the reception operation with respect to a base station that is not performing data transmission and reception (hereinafter, may be referred to as a non-active base station). The UE may perform the reception operation by switching the transceiver of the UE itself while being connected to a base station that performs data transmission and reception (hereinafter, may be referred to as an active base station). The non-active base station may be, for example, a base station facing an RRC in the RRC_IDLE state or the RRC_INACTIVE state. The active base station may be, for example, a base station facing an RRC in the RRC_CONNECTED state. The UE may be a receiver having only one transceiver.

[0294] The UE may notify the active base station of information regarding the timing for receiving the synchronization signal, the system information, and / or the paging from the non-active base station. The UE may request the active base station to avoid paging collision from the non-active base station. The above-mentioned information may be included in the request. The UE may switch the reception destination to the non-active base station at the timing.

[0295] The reception timing may include the time required for the UE to switch the transceiver. This can improve the reliability of the operation of receiving the synchronization signal, the system information, and / or the paging from the non-active base station, for example.

[0296] The UE discloses the following (1) to (9) as information regarding the above-mentioned reception timing notified to the active base station, that is, information regarding the timing at which the UE receives a synchronization signal, system information, and / or paging from a non-active base station.

[0297] (1) Information regarding the identifier of the non-active base station.

[0298] (2) Information regarding the synchronization signal transmission timing of the non-active base station.

[0299] (3) Information regarding the numerology of the non-active base station.

[0300] (4) Information regarding the frame timing of the non-active base station.

[0301] (5) Information used for deriving the synchronization signal transmission timing of the non-active base station.

[0302] (6) Information regarding the beam received from the non-active base station.

[0303] (7) Information regarding the system information transmission timing of the non-active base station.

[0304] (8) Information regarding the paging reception timing from the non-active base station.

[0305] (9) Combinations of the above (1) to (8).

[0306] The information in the above (1) may be, for example, the base station identifier of the non-active base station or the cell identifier. As a result, for example, the active base station can grasp the non-active base station from which the UE should receive a synchronization signal, system information, and / or paging. As a result, it is possible to avoid the complexity regarding scheduling by the active base station.

[0307] The information in the above (2) may be, for example, the frame timing at which the non-active base station transmits the SS burst, for example, the SFN. The SFN may be, for example, the SFN at the start of the SS burst or the SFN at the end of the SS burst. This enables, for example, reduction of the processing amount of scheduling in the active base station. Also, even when there is a timing offset between the active base station and the non-active base station, the non-active base station can receive the synchronization signal, system information, and / or paging.

[0308] As another example, the information in the above (2) may include information regarding the time at which the non-active base station transmits the SS burst. The information regarding the time may include, for example, the time at the start point of the SS burst, the time regarding the end point of the SS burst, the information regarding the duration of the SS burst, or a plurality of the above-mentioned information may be included. This enables, for example, reduction of the processing amount of scheduling in the active base station.

[0309] The information in the above (3) may be, for example, the subcarrier spacing, slot length, or symbol length used when the UE receives the synchronization signal, system information, and / or paging from the non-active base station, or may be the parameter μ disclosed in Section 4.2 of Non-Patent Document 13 (TS38.211). This enables, for example, improvement of the reliability of the operation of avoiding the synchronization signal, etc. from the non-active base station in the scheduling by the active base station.

[0310] The information in (4) above may be the same as the information in (4) above used for paging collision avoidance disclosed in Embodiment 1. This information may be, for example, information regarding the difference in frame timing between an active base station and a non-active base station. Thereby, for example, the processing amount of scheduling in the active base station can be reduced. As another example, the information in (4) above may be a predetermined time point in the non-active base station, for example, the time at the boundary of a predetermined SFN. Thereby, for example, the processing amount required for the UE to make the notification can be reduced.

[0311] The information in (5) above may include information regarding the period of the SS burst, or may include information indicating whether the SS burst is included in the first half or the second half of the frame. Thereby, for example, the processing amount of scheduling in the active base station can be reduced.

[0312] The information in (6) above may be information regarding the beam used by the UE to receive the SS block from the non-active base station. This information may be, for example, the identifier of the SS block within the SS burst. The active base station may use this information to refrain from transmitting and receiving with the UE only at the timing of the SS block received by the UE. Thereby, for example, the communication rate between the UE and the active base station can be improved.

[0313] As another example, the information in (6) above may be information regarding the beam candidates used by the UE to receive the SS block from the non-active base station. The information regarding the beam candidates may be, for example, the identifier of the SS block transmitted using the beam around the SS block received by the UE. Thereby, for example, the communication rate between the UE and the active base station can be improved. At the same time, even when the beam of the non-active base station where the UE is located changes, the UE can receive the SS block from the non-active base station.

[0314] The information in (6) above may be information regarding a beam or its candidates used by the UE to receive system information from a non-active base station, or may be information regarding a beam or its candidates used for paging reception.

[0315] The information in (7) above may be, for example, information regarding the scheduling of system information transmitted by a non-active base station. The information regarding the scheduling may be, for example, pdcch-ConfigSIB1 disclosed in Non-Patent Document 24 (TS38.331). This makes it possible to reduce the processing amount of scheduling in the active base station, for example.

[0316] The information in (8) above may be information regarding the paging timing of a non-active base station. The information may be the same as the information in (2) above used for paging collision avoidance disclosed in Embodiment 1. This makes it possible to reduce the processing amount of scheduling in the active base station, for example.

[0317] As another example, the information in (8) above may be information used for deriving the paging timing of a non-active base station. The information may be the same as the information in (5) above used for paging collision avoidance disclosed in Embodiment 1. This makes it possible to reduce the amount of signaling from the UE to the active base station and, at the same time, reduce the processing amount of scheduling in the active base station.

[0318] The UE may transmit the notification to the active base station using RRC signaling. This makes it possible for the UE to notify the active base station of a large amount of information, for example.

[0319] As another example, the UE may transmit the notification to the active base station using MAC signaling. This makes it possible for the UE to execute the notification quickly while ensuring reliability by HARQ retransmission control, for example.

[0320] As another example, the UE may send the notification to the active base station using L1 / L2 signaling. By doing so, for example, the UE can execute the notification more quickly.

[0321] As another example, the UE may send the notification to the AMF connected to the active base station using NAS signaling. By doing so, for example, it becomes unnecessary to transfer the information included in the notification between base stations along with the handover of the UE. As a result, the amount of signaling between base stations can be reduced.

[0322] As another example, the above-described methods may be combined. For example, the UE may notify the active base station of the information of the above-described (1) to (5), (7), and / or (8) using RRC signaling, and notify the active base station of the information of the above-described (6) using L1 / L2 signaling. By doing so, for example, a large amount of information can be quickly notified from the UE to the active base station.

[0323] The active base station may change the scheduling for the UE using the notification from the UE. The change may be, for example, not to allocate transmission and reception to the UE at the timing when the UE receives a synchronization signal, system information, and / or paging from a non-active base station. The active base station may notify the UE of information regarding the changed scheduling. The information may be, for example, information regarding the timing at which the UE should perform PDCCH reception operation, for example, a control resource set (CORESET) allocated to the UE, or information regarding a configured grant. By doing so, for example, the reliability of communication between the active base station and the UE can be improved.

[0324] The active base station may change the scheduling for the UE by using the notification from the UE. As another example of change, for instance, a period during which transmission and reception are not performed between the active base station and the UE may be set. The active base station may notify the UE of the period. The UE may perform transmission and reception with the non-active base station during the period. In the UE, it becomes possible to time-division multiplex the transmission and reception with the active base station and the transmission and reception with the non-active base station. By setting the period to be relatively long, the UE does not have to alternately execute communication with the active base station and communication with the non-active base station frequently. It becomes possible to improve the usage efficiency of radio resources.

[0325] The UE may switch the transmitter / receiver of the own UE to be directed to the non-active base station or switch it to be directed to the active base station by using the information received from the active base station. For example, the UE may switch the transmitter / receiver of the own UE to be directed to the non-active base station at the paging reception timing from the non-active base station. As a result, for example, the UE can receive paging from the non-active base station.

[0326] Another solution is disclosed. The UE may notify the non-active base station of information regarding the transmission and reception between the own UE and the active base station. In the foregoing, the RRC state of the UE with respect to the non-active base station may transition to RRC_CONNECTED. The non-active base station may change the synchronization signal and / or paging timing by using the notification. For example, the non-active base station may avoid the timing scheduled by the active base station for the UE and allocate the synchronization signal and / or paging timing. The change in the non-active base station may be the same as, for example, the method disclosed in Embodiment 1. As a result, for example, while ensuring the communication rate between the active base station and the UE, it becomes possible to receive the synchronization signal, system information, and / or paging of the non-active base station.

[0327] As information on transmission and reception between a UE and an active base station, which the UE notifies to an inactive base station, the following (1) to (10) are disclosed.

[0328] (1) Information on the identifier of the active base station.

[0329] (2) Information on the synchronization signal transmission timing of the active base station.

[0330] (3) Information on the numerology of the active base station.

[0331] (4) Information on the frame timing of the active base station.

[0332] (5) Information used for deriving the synchronization signal transmission timing of the active base station.

[0333] (6) Information on the beam received from the active base station.

[0334] (7) Information on the system information transmission timing of the active base station.

[0335] (8) Information on the paging reception timing from the active base station.

[0336] (9) Information on scheduling in the active base station.

[0337] (10) Combinations of the foregoing (1) to (9).

[0338] The information in (1) to (8) above may be the same as the information regarding the reception timing that the UE notifies the active base station, that is, the information in (1) to (8) above disclosed as the information regarding the timing at which the UE receives the synchronization signal, system information, and / or paging from the non-active base station. For example, according to the information in (8) above, the UE can receive system information change and / or emergency information from the active base station. At the same time, the non-active base station can change the timing of the synchronization signal, system information, and / or paging.

[0339] The information in (9) above may be, for example, information regarding the timing at which the UE should perform the PDCCH reception operation of the active base station, for example, a control resource set (CORESET) allocated to the UE, or information regarding a configured grant from the active base station. Thus, for example, the non-active base station can change the timing of the synchronization signal, system information, and / or paging without affecting the communication between the active base station and the UE.

[0340] When receiving the synchronization signal from the non-active base station, the UE may use a measurement gap. For example, the UE may receive the synchronization signal from the non-active base station using a pre-set measurement gap. Also, for example, the active base station may set a measurement gap for the UE to allow communication with the non-active base station. A conventional measurement gap may be used. By eliminating the need for new processing, the complexity of these processes can be avoided. Alternatively, a new gap may be provided, and the conventional measurement gap setting method may be used as the setting method. By providing a new gap, the gap period can be optimally set for communication with the non-active base station. Thus, for example, the UE can establish the synchronization of the downlink signal with the non-active base station while maintaining the communication rate with the active base station.

[0341] As another example, when receiving a synchronization signal from a non-active base station, the UE may not use a measurement gap. For example, when the active base station and the non-active base station use the same frequency band for the UE, the measurement gap may not be used. This can improve the efficiency in a communication system, for example.

[0342] The method disclosed in the second embodiment may be used for paging reception from an active base station. For example, at the paging reception timing, the UE may switch the transceiver of the UE itself from data transmission / reception with the active base station to paging reception from another active base station. This enables the UE to receive system information change and / or emergency information from another active base station, for example.

[0343] Another solution is disclosed. The UE may not notify the active base station of information regarding the reception timing of a synchronization signal, system information, and / or paging from the non-active base station. At the reception timing, the UE may switch the transceiver of the UE itself to the non-active base station. This can avoid the complexity of the process of the UE receiving a signal from the non-active base station, for example.

[0344] In the foregoing, retransmission of transmission / reception between the active base station and the UE may be performed. The retransmission may be, for example, retransmission for transmission / reception that occurred during the period when the UE switched the transceiver of the UE itself to the non-active base station. This can improve the reliability of transmission / reception between the active base station and the UE, for example.

[0345] The method disclosed in Embodiment 2 may be applied to a UE having a plurality of transceivers. The UE may be connected to one NW, for example, using a plurality of transceivers. The UE may be connected to a plurality of base stations in one NW. The UE may form dual connectivity with the plurality of base stations. The UE may switch its transceiver to a non-active base station at a timing when a synchronization signal, system information, and / or paging is transmitted from a non-active base station in another NW.

[0346] When the UE forms the aforementioned dual connectivity, the transceiver for the secondary base station may be switched to a non-active base station. This enables, for example, maintaining communication between the UE and the master base station, and as a result, maintaining the robustness of the communication system.

[0347] As another example, the transceiver for the master base station may be switched to a non-active base station. This enables, for example, maintaining communication between the UE and the secondary base station when high-speed communication is being performed between the UE and the secondary base station. As a result, the transmission speed in the communication system can be maintained.

[0348] When the transceiver for the master base station is switched to a non-active base station, the secondary base station may become the master base station. This enables, for example, performing handover in the UE with a small amount of signaling.

[0349] According to Embodiment 2, the UE can receive a synchronization signal, system signal, and / or paging from a non-active base station. As a result, the UE can quickly resume communication with the base station.

[0350] Modification Example 1 of Embodiment 2. In Embodiment 2, the switching of the transmitter / receiver of the UE from the active base station to the non-active base station may be applied to the random access process between the UE and the non-active base station.

[0351] The UE may notify the active base station of information regarding the random access process between the UE and the non-active base station. The information may include information regarding the timing of the random access process that the UE performs with the non-active base station. The active base station may not allocate the transmission / reception timing between the UE and its own base station at this timing.

[0352] The following (1) to (8) are disclosed as information regarding the random access process between the UE and the non-active base station that the UE notifies the active base station.

[0353] (1) Information regarding the identifier of the non-active base station.

[0354] (2) Information regarding the PRACH transmission timing to the non-active base station.

[0355] (3) Information regarding the numerology of the non-active base station.

[0356] (4) Information regarding the frame timing of the non-active base station.

[0357] (5) Information regarding the RAR reception timing from the non-active base station.

[0358] (6) Information regarding the beam received from the non-active base station.

[0359] (7) Information regarding the preamble of the PRACH to the non-active base station.

[0360] (8) The combination of the above (1) to (7).

[0361] The information in (1) above may be the same as (1) of the information regarding the synchronization signal, system information, and / or paging reception timing (hereinafter sometimes referred to as the synchronization and other timing of the non-active base station) transmitted from the non-active base station disclosed in Embodiment 2.

[0362] The information in (2) above may be information regarding the start timing of the PRACH transmitted by the UE. The information may be an SFN, subframe number, slot number, or symbol number, or a combination thereof as described above. The information may include information regarding the length of the PRACH transmitted by the UE, or may include information regarding the end timing of the PRACH. Thereby, for example, the UE can notify information regarding the PRACH transmitted by the UE with a small amount of signaling.

[0363] As another example, the information in (2) above may include information regarding the time of the PRACH transmitted by the UE. The information regarding the time may include, for example, the time at the start point of the PRACH, the time regarding the end point of the PRACH, the information regarding the length of the PRACH, or may include a plurality of the above-mentioned information. Thereby, for example, the processing amount of scheduling in the active base station can be reduced.

[0364] The information in (3) and (4) above may be the same as (3) and (4) of the synchronization and other timing information of the non-active base station, respectively.

[0365] The information in (5) above may include, for example, information regarding the start point of the RAR reception timing, information regarding the end point, or information regarding the length of the RAR reception timing. The information may be in the same format as (2) above, for example. As another example, the information in (5) above may be the ra-ResponseWindow disclosed in Non-Patent Document 24. Thereby, for example, in the UE, it is possible to prevent a collision between the transmission and reception with the active base station and the timing of the RAR from the non-active base station.

[0366] The information in (6) above may be the same as that of the timing information such as synchronization of the non-active base station.

[0367] The information in (7) above may include, for example, information regarding the preamble of the PRACH transmitted by the UE to the non-active base station. The active base station may use this information to assign a preamble different from the preamble to the UE for PRACH transmission to the active base station itself. This can prevent, for example, the active base station from misidentifying the PRACH transmitted from the UE to the non-active base station as the PRACH for the active base station itself.

[0368] Similar to Embodiment 2, the UE may perform the notification using RRC signaling, MAC signaling, or L1 / L2 signaling. As another example, the UE may perform the notification using NAS signaling to the AMF connected by the active base station.

[0369] The active base station may not perform uplink and / or downlink scheduling for the UE at the PRACH transmission timing from the UE to the non-active base station and / or the RAR transmission timing from the non-active base station to the UE using the notification. Also, at this timing, transmission and reception to / from the UE may not be assigned.

[0370] FIG. 27 and FIG. 28 are sequence diagrams showing a first example of an operation in which a multi-SIM UE performs random access processing with a non-active base station. FIG. 27 and FIG. 28 are connected at the position of the boundary line BL2728. In FIGS. 27 and 28, the UE is connected to two NWs (NW#1, NW#2), and is connected to gNB#1 under NW#1 and gNB#2 under NW#2. In FIGS. 27 and 28, AMF#1 and AMF#2 exist under NW#1 and NW#2, respectively. In the example shown in FIGS. 27 and 28, gNB#1 is an active base station and gNB#2 is a non-active base station. In FIGS. 27 and 28, the same processing as that in FIGS. 16 and 17 is given the same step numbers, and common explanations are omitted.

[0371] Steps ST1601 to ST1603 shown in FIG. 27 are the same as those in FIG. 16.

[0372] In step ST2304 shown in FIG. 27, data is transmitted and received between the UE and gNB#1.

[0373] In step ST2306 shown in FIG. 27, gNB#1 notifies the UE of system information. In step ST2307, gNB#2 notifies the UE of system information. The notification in step ST2307 includes parameters related to PRACH transmission to gNB#2, for example, information related to PRACH transmission timing. The notification in step ST2307 may include information related to RAR transmission from gNB#2.

[0374] In step ST2308 shown in FIG. 27, the UE acquires the RACH timing in gNB#2.

[0375] In step ST2310 shown in FIG. 27, the UE notifies gNB#1 of information related to RACH between the UE and gNB#2. In step ST2312, gNB#1 schedules the UE while avoiding the transmission timings of PRACH and RAR between the UE and gNB#2.

[0376] In step ST2314 shown in FIG. 27, data is transmitted and received between the UE and gNB#1. The data transmission and reception in step ST2314 is performed while avoiding the transmission timings of PRACH and RAR between the UE and gNB#2.

[0377] Suppose that uplink data from the UE to gNB#2 has occurred in step ST2320 shown in FIG. 28.

[0378] In step ST2322 shown in FIG. 28, the UE transmits a PRACH to gNB#2. gNB#1 does not schedule the UE at the timing of step ST2322.

[0379] In step ST2324 shown in FIG. 28, gNB#2 transmits an RAR to the UE. gNB#1 does not schedule the UE at the timing of step ST2324.

[0380] In step ST2326 shown in FIG. 28, the UE requests the establishment of RRC with gNB#2. This request may be made using RRC signaling, for example, the RRC establishment request (RRCSetupRequest) of Non-Patent Document 24 (TS38.331). In step ST2328, gNB#2 instructs the UE to perform RRC establishment. This instruction may use RRC signaling, for example, the RRC establishment (RRCSetup) of Non-Patent Document 24 (TS38.331). In step ST2330 shown in FIG. 28, the UE notifies gNB#2 of the completion of RRC establishment. This notification may use RRC signaling, for example, the RRC establishment complete (RRCSetupComplete) of Non-Patent Document 24 (TS38.331). Through step ST2330, the RRC connection between the UE and gNB#2 is established.

[0381] In step ST2332 shown in FIG. 28, data is transmitted and received between the UE and gNB#2. In step ST2334 shown in FIG. 28, data is transmitted and received between the UE and gNB#1.

[0382] As another example, the UE may give the notification to the active base station after uplink data is generated to the non-active base station. Thereby, for example, scheduling that avoids the transmission timings of PRACH and RAR performed by the active base station can be executed after the uplink data is generated. As a result, the communication efficiency between the UE and the active base station can be improved.

[0383] FIGS. 29 and 30 are sequence diagrams showing a second example of the operation in which the multi-SIM mounted UE performs random access processing with a non-active base station. FIGS. 29 and 30 are connected at the position of the boundary line BL2930. In FIGS. 29 and 30, the UE is connected to two NWs (NW#1, NW#2), and is connected to gNB#1 under NW#1 and gNB#2 under NW#2. In FIGS. 29 and 30, AMF#1 and AMF#2 exist under NW#1 and NW#2, respectively. In the example shown in FIGS. 29 and 30, gNB#1 is an active base station and gNB#2 is a non-active base station. In FIGS. 29 and 30, the same step numbers are assigned to the same processes as those in FIGS. 16 to 17 and FIGS. 27 to 28, and the common descriptions are omitted.

[0384] Steps ST1601 to ST1603 shown in FIG. 29 are the same as those in FIG. 16. Steps ST2304 to ST2308 and ST2320 shown in FIG. 29 are the same as those in FIG. 27.

[0385] In step ST2410 shown in FIG. 29, the UE notifies gNB#1 of information regarding RACH with gNB#2. The UE may perform step ST2410 after step ST2320. In step ST2412, gNB#1 performs scheduling for the UE while avoiding the transmission timings of PRACH and RAR between the UE and gNB#2.

[0386] In step ST2414 shown in FIG. 30, data is transmitted and received between the UE and gNB#1. The data transmission and reception in step ST2414 is performed while avoiding the transmission timings of PRACH and RAR between the UE and gNB#2.

[0387] The steps ST2322 to ST2334 shown in FIG. 30 are the same as those in FIG. 28.

[0388] As another example, the active base station may stop data transmission and reception between the UE and the active base station during the random access process between the UE and the non-active base station. The UE may notify the active base station of the start of the random access process. The active base station may use the notification to stop data transmission and reception with the UE. The UE may notify the active base station of the end of the random access process. The active base station may use the notification to resume data transmission and reception with the UE. This enables, for example, the random access process between the UE and the non-active base station to be executed quickly.

[0389] The UE may transmit the notification to the active base station using L1 / L2 signaling. This enables, for example, the UE to notify the notification quickly. As another example, the UE may notify the notification using MAC signaling. This enables, for example, the reliability of the notification to be ensured by HARQ retransmission control. As another example, the UE may notify the notification using RRC signaling. This enables, for example, the UE to notify the active base station of a lot of information.

[0390] Figures 31 and 32 are sequence diagrams showing a third example of the operation in which a multi-SIM UE performs random access processing with a non-active base station. Figures 31 and 32 are connected at the position of the boundary line BL3132. In Figures 31 and 32, the UE is connected to two NWs (NW#1, NW#2), and is connected to gNB#1 under NW#1 and gNB#2 under NW#2. In Figures 31 and 32, AMF#1 and AMF#2 exist under NW#1 and NW#2, respectively. In the example shown in Figures 31 and 32, gNB#1 is an active base station and gNB#2 is a non-active base station. In Figures 31 and 32, the same processing as in Figures 16 to 17 and Figures 27 to 28 is assigned the same step numbers, and common explanations are omitted.

[0391] Steps ST1601 to ST1603 shown in Figure 31 are the same as those in Figure 16. Steps ST2304 to ST2320 shown in Figure 31 are the same as those in Figures 27 and 28.

[0392] In step ST2520 shown in Figure 32, the UE notifies gNB#1 of starting random access processing between the UE and gNB#2 on the occasion of generating data for gNB#2. The UE may perform the notification using L1 / L2 signaling, MAC signaling, or RRC signaling. In step ST2521, gNB#1 stops transmission and reception with the UE.

[0393] Steps ST2322 to ST2332 shown in Figure 32 are the same as those in Figure 28.

[0394] In step ST2532 shown in Figure 32, the UE notifies gNB#1 that the random access processing between the UE and gNB#2 has been completed. The UE may perform the notification using L1 / L2 signaling, MAC signaling, or RRC signaling. In step ST2533, gNB#1 resumes transmission and reception with the UE.

[0395] Step ST2334 shown in FIG. 32 is the same as that in FIG. 28.

[0396] As another example, the UE may request the active base station to suspend the RRC connection with the base station or request the release of the RRC connection. The UE may make the request using RRC signaling. The RRC signaling may be newly provided signaling, for example, RRC Suspend Request or RRC Release Request. The active base station may suspend or release the connection between the UE and the active base station. After the connection suspension or connection release between the UE and the active base station, the UE may start the random access procedure with the non-active base station. This can avoid, for example, the complexity of the communication system.

[0397] FIGS. 33 and 34 are sequence diagrams showing a fourth example of the operation in which the multi-SIM UE performs a random access procedure with the non-active base station. FIGS. 33 and 34 are connected at the position of the boundary line BL3334. In FIGS. 33 and 34, the UE is connected to two NWs (NW#1, NW#2), and is connected to gNB#1 under NW#1 and gNB#2 under NW#2. In FIGS. 33 and 34, AMF#1 and AMF#2 exist under NW#1 and NW#2, respectively. In the example shown in FIGS. 33 and 34, gNB#1 is the active base station and gNB#2 is the non-active base station. FIGS. 33 and 34 show an example in which the RRC connection between the UE and gNB#1 is suspended due to the generation of uplink data from the UE to gNB#2. In FIGS. 33 and 34, the same step numbers are assigned to the same processes as those in FIGS. 16 to 17 and FIGS. 27 to 28, and the common descriptions are omitted.

[0398] Steps ST1601 to ST1603 shown in FIG. 33 are the same as those in FIG. 16. Steps ST2304 to ST2320 shown in FIG. 33 are the same as those in FIGS. 27 and 28.

[0399] In step ST2620 shown in FIG. 34, the UE requests the suspension of the RRC connection from gNB#1. The UE may make this request using RRC signaling. The RRC signaling may be newly provided signaling, for example, RRC Suspend Request.

[0400] In step ST2621 shown in FIG. 34, gNB#1 instructs the UE to suspend the RRC connection. For this instruction from gNB#1 to the UE, RRC signaling, for example, RRC Suspend disclosed in Non-Patent Document 24 (TS38.331), may be used. The UE may suspend the RRC connection with gNB#1 based on the suspension instruction in step ST2621. In step ST2622, the UE notifies gNB#1 of the completion of the RRC connection suspension. For this notification from the UE to gNB#1, RRC signaling, for example, RRC Suspend Complete disclosed in Non-Patent Document 24 (TS38.331), may be used.

[0401] After the completion of the RRC connection suspension between the UE and gNB#1, the UE starts the random access procedure with gNB#2. Steps ST2322 to ST2332 shown in FIG. 34 are the same as those in FIG. 28.

[0402] In FIGS. 33 and 34, the case where the RRC connection between the UE and gNB#1 is suspended is shown, but the RRC connection may be released. In step ST2620, the UE may request the release of the RRC connection from gNB#1. In step ST2621, gNB#1 may instruct the UE to release the RRC connection. In step ST2622, the UE may notify gNB#1 of the release of the RRC connection. This can reduce, for example, the memory usage in the UE.

[0403] As another example, the UE may request the AMF connected to the active base station to release the connection between the active base station and the NW to which it is connected, or may request to suspend the connection. The UE may request release or suspension from the AMF using NAS signaling. The AMF may use the request to release or suspend the connection with the UE. For example, the AMF may instruct the active base station to release the RRC connection with the UE, or may instruct to suspend the RRC connection. The active base station may use the instruction to instruct the UE to release or suspend the RRC connection. After the connection to the NW is released, the UE may start the random access procedure with the non-active base station. Thereby, for example, the same effect as described above can be obtained.

[0404] According to this Modification Example 1, it is possible to secure the time for the random access procedure between the UE and the non-active base station. As a result, it is possible to start or resume the connection with the non-active base station.

[0405] Embodiment 3. In Embodiment 2, a method for avoiding a collision between scheduling by the active base station and the timing such as synchronization of the non-active base station was disclosed. In this Embodiment 3, a method for avoiding a scheduling collision when a multi-SIM UE communicates with the active base stations of multiple NWs is disclosed.

[0406] Allocate the timing when communication is possible between the UE and the base stations of each NW in a time division manner.

[0407] The UE may perform the allocation. The UE may notify each NW base station of information regarding the allocation. Each NW base station may use the allocation to perform transmission and reception with the UE.

[0408] The UE may perform the notification using RRC signaling. This enables, for example, the notification of a large amount of information. As another example, the UE may perform the notification using MAC signaling. This enables, for example, the UE to execute the notification quickly. As another example, the UE may perform the notification using L1 / L2 signaling. This enables, for example, the UE to execute the notification even more quickly.

[0409] Other solutions are disclosed. The allocation may be determined by a base station (hereinafter sometimes referred to as a determining base station). For example, the primary NW disclosed in Embodiment 1 may determine the allocation. The base station of the primary NW may notify the UE of the allocation.

[0410] The UE may notify the determining base station of the information necessary for the determination of the allocation. The UE may use RRC signaling, MAC signaling, L1 / L2 signaling, or a combination of multiple of the foregoing for the notification. The determining base station may determine the allocation using the information.

[0411] Examples of the information necessary for the determination of the allocation are disclosed as follows (1) to (7).

[0412] (1) Information regarding the identifiers of base stations of other NWs.

[0413] (2) Information regarding the scheduling of base stations of other NWs.

[0414] (3) Information regarding the numerology of base stations of other NWs.

[0415] (4) Information regarding the frame timing of base stations of each NW.

[0416] (5) Information regarding the timing for receiving synchronization signals, system information, and / or paging from base stations of other NWs.

[0417] (6) Information regarding random access processing with base stations of other NWs.

[0418] (7) Combinations of the aforementioned (1) to (6).

[0419] The information in the aforementioned (1) may be, for example, the base station identifier of a base station of another NW or the cell identifier. As a result, for example, the determining base station can grasp other base stations. Consequently, it is possible to avoid the complexity regarding the allocation by the determining base station.

[0420] The information in the aforementioned (2) may be, for example, the control resource set (CORESET) allocated by a base station of another NW to a UE, information regarding scheduling dynamically allocated by the base station, configured scheduling (e.g., semi-persistent scheduling and / or configured grant), information regarding the allocation of PUCCH, or information regarding the allocation of SRS. The determining base station may determine the allocation using the information in the aforementioned (2). As a result, for example, it is possible to prevent scheduling collisions between the determining base station and other base stations.

[0421] The information in the aforementioned (3) may be, for example, the subcarrier spacing, slot length, or symbol length used by the UE for transmission and reception with a base station of another NW, or the parameter μ disclosed in Section 4.2 of Non-Patent Document 13 (TS38.211). As a result, for example, in scheduling by the active base station, it is possible to improve the reliability of operations to avoid synchronization signals, etc., from non-active base stations.

[0422] The information of the foregoing (4) may be the same as the information of (4) disclosed as the information used for paging collision avoidance in Embodiment 1. The information may be, for example, information regarding the difference in frame timing between the determination base station and other base stations. As another example, the information of the foregoing (4) may be a time at a predetermined time point in each base station, for example, a time at the boundary of a predetermined SFN. Thereby, for example, even when there is a frame offset between the determination base station and other base stations, it is possible to avoid a scheduling collision between base stations.

[0423] The information of the foregoing (5) may be information in which the non-active base station is replaced with a base station of another NW in the information of (1) to (9) disclosed as the information regarding the timing at which the UE receives a synchronization signal, system information, and / or paging from the non-active base station in Embodiment 2. Thereby, for example, it is possible to perform both data transmission and reception with one base station and reception of a synchronization signal, system information, and / or paging from another base station (for example, reception of paging accompanying system information update).

[0424] The information of the foregoing (6) may be the information of (1) to (8) disclosed as the information regarding random access processing with a base station of another NW in Modification Example 2 of Embodiment 1. Thereby, for example, it is possible to perform both data transmission and reception with one base station and random access processing with another base station (for example, random access processing for on-demand system information request).

[0425] The determination base station may perform the notification of the allocation using RRC signaling. Thereby, for example, the determination base station can notify a lot of information. As another example, the determination base station may perform the notification using MAC signaling. Thereby, for example, the determination base station can execute the notification quickly. As another example, the determination base station may perform the notification using L1 / L2 signaling. Thereby, for example, the determination base station can execute the notification even more quickly.

[0426] The UE may notify other NW base stations of the allocation received from the determining base station. The UE may perform such notification using RRC signaling, MAC signaling, or L1 / L2 signaling. Other NW base stations may perform transmission and reception with the UE using the allocation. This can prevent scheduling collisions for the UE even between base stations of different NWs, for example.

[0427] Other NW base stations may request the UE to change the allocation. The UE may notify the determining base station of the request. The determining base station may change the allocation using the request. This can improve the efficiency in a communication system, for example.

[0428] Other solutions are disclosed. The determining base station may notify other NW base stations of the allocation. An interface may be provided between the determining base station and other NW base stations. The interface may pass through the UPF of each other NW. The determining base station may notify other NW base stations of the allocation using the interface.

[0429] Other solutions are disclosed. A default allocation pattern may be provided. The default pattern may be stored in, for example, the SIM of the UE. The UE may notify each NW base station of the default pattern. Each NW base station may perform transmission and reception with the UE using the default allocation. This can avoid the complexity regarding collision avoidance of scheduling for the UE between base stations, for example.

[0430] A plurality of default allocation patterns may be provided. For example, the plurality of allocation patterns may be provided for each SIM. Priorities may be provided for the plurality of allocation patterns. For example, when the allocation patterns set for each SIM conflict with each other, one of the allocation patterns may be prioritized. The UE may notify each base station of the allocation pattern with a higher priority. This can avoid, for example, the complexity regarding collision avoidance of scheduling for the UE among each base station.

[0431] As another example, the default allocation pattern may be provided by a standard. This can quickly execute, for example, collision avoidance of scheduling for the UE among each base station.

[0432] The method disclosed in the third embodiment may be used to avoid conflicts of UE capabilities. For example, when a conflict occurs among the UE capabilities that the UE has with each NW, priorities may be provided for each capability. The priority may be, for example, statically given. Alternatively, the priority may change dynamically. For example, the UE capabilities for the primary NW may be prioritized. This can prevent, for example, malfunctions of the communication system caused by conflicts of UE capabilities.

[0433] The foregoing solutions may be combined. For example, the UE may notify the determination base station and the base stations of other NWs of the default allocation pattern. The determination base station may change the allocation using the allocation pattern. The determination base station may notify the UE of information regarding the changed allocation. The UE may notify the base stations of other NWs of information regarding the changed allocation. The determination base station and the base stations of other NWs may perform transmission and reception with the UE using the changed allocation. This can improve, for example, the flexibility of scheduling the UE at each base station.

[0434] According to Embodiment 3, it is possible to avoid scheduling collisions when a multi-SIM UE communicates with active base stations of multiple NWs. As a result, the reliability of communication between the UE and the multiple base stations can be improved.

[0435] Modification Example 1 of Embodiment 3. When a multi-SIM UE communicates with active base stations of multiple NWs, inter-NW preemption may be performed. Inter-NW preemption may be, for example, a transmission and reception in which time resources allocated for transmission and reception between the UE and one NW are reassigned for higher-priority transmission and reception between the UE and another NW.

[0436] Signaling for inter-NW preemption may be provided between the UE and the base station.

[0437] A signal requesting inter-NW preemption may be provided. For example, in uplink inter-NW preemption, an SR for inter-NW preemption may be provided. A PUCCH for communicating the SR may be provided. By differentiating the PUCCH for the SR and the PUCCH of the conventional SR in terms of time and / or frequency axis and / or code resources, the SR and the conventional SR can be distinguished.

[0438] The notification of the signal from the UE to the base station may use, for example, L1 / L2 signaling, MAC signaling, or RRC signaling. In the case of L1 / L2 signaling, for example, the aforementioned PUCCH may be provided and the notification may be made using the PUCCH. The resources of the PUCCH may be preset by the base station for the UE. By using L1 / L2 signaling, it is possible to notify a request for inter-NW preemption at an early stage.

[0439] For example, in the uplink inter-NW preemption, the UE may transmit an SR for the inter-NW preemption to the base station. The base station may be the communication partner for the communication related to the inter-NW preemption. The SR may include information indicating that it is an inter-NW preemption. The information may be, for example, an identifier indicating that it is an inter-NW preemption. The information may be, for example, information indicating the priority in the inter-NW preemption, such as information related to QoS. The information may be, for example, information related to the communicable timing for the preemption assigned by the UE.

[0440] The base station may use the SR to allocate frequency and / or time resources for the inter-NW preemption to the UE. The base station may notify the UE of information related to the frequency and / or time resources allocated to the UE. The notification from the base station to the UE may be performed using, for example, L1 / L2 signaling, MAC signaling, or RRC signaling. The notification from the base station to the UE may be a dynamic grant or a configured grant. The UE may use the notification to perform inter-NW preemption communication with the base station.

[0441] In the assignment of the transmission and reception timings between the UE and each NW disclosed in Embodiment 3, there may be overlapping periods between the NWs. The UE may apply the SR for the aforementioned inter-NW preemption, for example, during the overlapping periods. For example, the UE may transmit the SR for the inter-NW preemption to one NW base station. When the UE transmits the SR, it may not perform communication with the base stations of other NWs. Alternatively, when the UE transmits information related to the communicable timing for the preemption assigned by the UE to the base station, the UE may not perform communication with the base stations of other NWs during the period of the timing. Thereby, for example, the UE can quickly start the NW preemption during the overlapping period.

[0442] For example, the SR for NW - to - NW pre - emption may include information indicating communication with base stations of other NWs. The UE may transmit the SR to one NW base station. When the UE transmits the SR, it may not communicate with the base station of the NW that transmitted the SR, but may communicate with the base stations of the other NWs. Alternatively, when the UE transmits information regarding communicable timing for pre - emption assigned by the UE to the base station, the UE may not communicate with the base station of the NW that transmitted the SR during the period of that timing, but may communicate with the base stations of the other NWs. As a result, for example, the base station of the NW that received the SR can recognize that the UE communicates with the base stations of other NWs. Thus, the base station of the NW that received the SR does not have to perform reception processing from the UE, and the power consumption of the base station can be reduced.

[0443] During the above - mentioned overlapping period, the base station may notify the UE of information regarding frequency and / or time resource allocation. The UE may perform a reception operation of the information triggered by the above - mentioned SR transmission. When the UE performs the reception operation of the information, it may not perform transmission and reception with other NWs. As a result, for example, the base station can quickly notify the UE of the information.

[0444] During the above - mentioned overlapping period, NW - to - NW pre - emption communication from the UE to the base station may be performed. The UE may perform NW - to - NW pre - emption communication with the base station triggered by receiving information regarding frequency and / or time resource allocation mentioned above. The base station may allocate NW - to - NW pre - emption communication from the UE during the overlapping period between NWs, or may allocate NW - to - NW pre - emption communication from the UE at the transmission and reception allocation timing with its own base station. When the UE performs NW - to - NW pre - emption communication, it may not perform transmission and reception with other NWs. As a result, for example, the UE can quickly execute high - priority uplink transmission to the base station.

[0445] The NW - to - NW pre - emption may be performed in the downlink communication. The base station may notify the UE of the occurrence of the downlink NW - to - NW pre - emption. The notification may be performed, for example, using L1 / L2 signaling, using MAC signaling, or using RRC signaling. The UE may continue to receive downlink from the base station using the notification. For example, the UE may not switch the transceiver for the base station to the base station of another NW. Thereby, for example, the UE can quickly receive high - priority downlink communication.

[0446] The UE may perform the reception operation of the downlink NW - to - NW pre - emption. The UE may perform the reception operation during the SS bursts from the base stations of other NWs. For example, the UE may perform the reception operation between the SS blocks constituting the SS burst. Thereby, for example, the UE can receive the downlink NW - to - NW pre - emption even while receiving the synchronization signal from another NW. As a result, the UE can quickly receive high - priority downlink communication.

[0447] The UE may notify each NW's base station of the information necessary for the determination of the NW - to - NW pre - emption. The information may be, for example, the same as the information (1) - (7) disclosed as the information necessary for determining the allocation of communication - available timings between the base stations of each NW in Embodiment 3. Each NW's base station may use the information to determine whether the communication with the UE becomes NW - to - NW pre - emption communication. For example, each NW's base station may use the information of (4) above, that is, the information regarding the frame timing of each NW's base station, to determine whether a scheduling collision occurs between the base stations of other NWs. Each NW's base station may determine that NW - to - NW pre - emption communication occurs when a scheduling collision occurs between the base stations of other NWs. Thereby, for example, the occurrence of NW - to - NW pre - emption communication in the communication system can be minimized, and the efficiency in the communication system can be improved.

[0448] There may be communication that allows the UE to communicate with any NW. Such communication may be, for example, communication of emergency information, such as communication in a Public Warning System (PWS). Each base station of each NW may perform such communication with the UE. This enables the UE to receive such communication quickly, for example.

[0449] The UE may delete the communication received repeatedly. For example, the UE may use only the communication received earliest and delete the communication received second and later. The communication may include an identifier indicating that it is the same information. The UE may use the identifier to detect duplication of the communication. This can prevent redundant alarm reception in the UE, for example.

[0450] Another solution is disclosed. Inter-NW preemption may be performed using an increase or decrease in transmission power. For example, inter-NW preemption may be communication in which the transmission power of high-priority communication is set high and the transmission power of low-priority communication is set low. Inter-NW preemption performed using an increase or decrease in transmission power may be performed when the UE has multiple transceivers. This can improve the reliability of high-priority communication, for example.

[0451] For example, in uplink inter-NW preemption, the UE may transmit an SR for inter-NW preemption to the base station with increased transmission power. The UE may perform transmission to the base station of another NW with decreased transmission power. The base station may use the SR to set the transmission power of the UE high. The base station may use the SR to notify the UE of a scheduling grant for inter-NW preemption. The grant may include information regarding uplink transmission power. The UE may use the notification to perform inter-NW preemption communication with increased transmission power to the base station.

[0452] According to the first modification example, preemption between NWs becomes possible in a multi-SIM UE, and as a result, it becomes possible to satisfy QoS in the communication system.

[0453] Embodiment 4. When a multi-SIM UE communicates with base stations of a plurality of NWs, a method for adjusting the power from the UE has not been disclosed. As a result, the power used for transmission from the UE to each base station may be excessive or insufficient.

[0454] In this Embodiment 4, a method for solving the above problems is disclosed.

[0455] The UE notifies each base station of the NW of the power that can be transmitted to the base station.

[0456] This power may be, for example, the maximum power that the UE can transmit minus the total of the transmission powers allocated to the base stations of other NWs.

[0457] The maximum power that the UE can transmit may be different for each NW. The maximum power that the UE can transmit may be notified to the UE from each base station of the NW. In this case, the power that can be transmitted for each NW of the UE can be determined, for example, as follows. Let Pa be the maximum power that can be transmitted for a certain NW for which the power to be determined is the target, and let Pb be the result of subtracting the total of the transmission powers allocated for other NWs other than the aforementioned one NW from the largest of the maximum transmission powers for each NW. In this case, the smaller of Pa and Pb may be determined as the power that can be transmitted for the aforementioned one NW. If no transmission power is allocated for other NWs, the total of the transmission powers allocated for other NWs other than the aforementioned one NW may be set to 0. This makes it possible to prevent, for example, the power transmitted by the UE to the aforementioned one NW from becoming excessive.

[0458] The UE may perform this notification using RRC signaling. This makes it possible for the UE to notify each base station of a lot of information, for example.

[0459] As another example, the UE may perform the notification using MAC signaling. As a result, for example, the UE can execute the notification quickly. The MAC signaling may be, for example, the same signaling as the PHR disclosed in Non-Patent Document 17 (TS38.321).

[0460] As another example, the UE may perform the notification using L1 / L2 signaling. As a result, for example, the UE can execute the notification even more quickly.

[0461] Each base station of the NW that has received the transmit power that can be transmitted from the UE may perform scheduling for communication with the UE using the information on the transmit power that can be transmitted from the UE. The scheduling may be, for example, the amount of resources allocated on the frequency axis, information on the transmit power of the UE, or information required for the UE to derive the transmit power. As a result, it is possible to avoid scheduling such that the power used for transmission from the UE to each base station becomes excessive or too small.

[0462] In determining the transmit power that can be transmitted from the UE, priorities may be set among the NWs. For example, the transmit power that can be transmitted from the UE is determined from the NW with a higher priority. A specific example of the case where the transmit power for the NW (referred to as NW1) with a predetermined priority has already been determined and then the transmit power for communication with a new NW (referred to as NW2) is determined is disclosed. The UE compares the priority of NW1 and the priority of NW2. If the priority of NW2 is higher, the transmit power already determined for NW1 is discarded, and the transmit power for NW2 is determined. Then, the transmit power for NW1 is determined again. If the priority of NW2 is lower, the transmit power for NW2 is determined by the above method using the transmit power already determined for NW1. By doing so, it is possible to preferentially allocate transmit power to communication with the NW with a higher priority.

[0463] As another method, priorities may be set for each service. Priorities may be set for each service for which communication is performed in each NW. The priority for each service may be included, for example, in the QoS of the service. Alternatively, if there is already information regarding priority in the QoS, the information regarding the priority may be used. The UE may determine the transmitable power for each NW using the priority for each service for which communication is performed in each NW. As a method for determining the transmitable power, the aforementioned method for determining the transmitable power may be applied. It becomes possible to preferentially allocate transmit power to the NW that performs communication for a service with a high priority.

[0464] When the UE re-determines the transmitable power for the NW, the UE may notify the base station of the NW of the re-determined transmitable power. The base station may perform scheduling using the notified transmitable power of the UE. By doing so, the base station of each NW can perform more optimal scheduling for the UE. The usage efficiency of the resources used in each NW can be improved.

[0465] Disclosed is a method for setting priorities. For example, priorities may be set between NWs. As another method, priorities may be set for each service. The priorities may be unified values between NWs in advance, or may be unified values between services. The priorities may be given to NWs in advance, or may be given to services in advance. The priority of a service may be given as the QoS of the service. The priorities may be notified from each NW to the UE. For example, the priorities may be notified when the UE performs a registration process with each NW. For example, the priorities may be notified when the UE performs a service request process or a PDU session establishment process with each NW. For example, the UE may set priorities. For example, a person may set priorities. The method for the UE or a person to set priorities may appropriately apply, for example, the primary NW / secondary NW setting method disclosed in Embodiment 1. By doing so, the UE can recognize the priorities. Also, the priority setting method disclosed here may be appropriately applied in the foregoing embodiments and variations.

[0466] A plurality of transmit powers may be provided for the base stations of each NW. For example, a transmit power may be provided when the UE performs inter-NW preemption communication with the NW. A transmit power may be provided for the NW when the UE performs inter-NW preemption communication with another NW different from the NW. Thereby, for example, the reliability of inter-NW preemption can be improved.

[0467] The UE may notify the base stations of each NW of information regarding the plurality of powers. The UE may perform the notification using RRC signaling, or using MAC signaling, or using L1 / L2 signaling.

[0468] The base station of each NW may notify the UE of information on which transmit power among the plurality of powers is to be used. The UE may use this information to derive the transmit power that can be transmitted to the base station. The base station may notify this information using RRC signaling. As a result, for example, the base station can notify the UE of a large amount of information. As another example, the base station may notify this information using MAC signaling. As a result, for example, the base station can notify this information quickly. As another example, the base station may notify this information using L1 / L2 signaling. As a result, for example, the base station can notify this information even more quickly.

[0469] As another example, the base station of each NW may not notify the UE of information on which transmit power among the plurality of powers is to be used. For example, when the plurality of powers are (a) the transmit power that can be transmitted when the UE performs inter-NW preemption communication with respect to the NW, (b) the transmit power that can be transmitted when NW preemption is not performed, and (c) the transmit power that can be transmitted to the NW when the UE performs inter-NW preemption communication with respect to another NW different from the NW, the information may not be notified from the base station to the UE. The UE may determine the transmit power that can be transmitted to the base station using information on NW preemption obtained from the base station, for example, information on a scheduling grant for inter-NW preemption communication. As another example, the UE may autonomously determine the transmit power that can be transmitted. For example, when the UE transmits an SR for inter-NW preemption communication to the base station of one NW, the UE may determine the transmit power that can be transmitted to the base station of each NW. As a result, for example, the amount of signaling between the base station and the UE can be reduced.

[0470] As another example when a plurality of transmit powers are provided for each base station of each NW, the transmit power may be provided for each uplink channel. For example, for each of PUSCH, PUCCH, uplink RS, and RACH, the transmit power may be provided for each base station of each NW. For each UCI included in PUCCH, the transmit power may be provided for each base station of each NW. For each of the uplink RSs, for example, for each of SRS, DMRS, and PRS, the transmit power may be provided for each base station of each NW. The UE may perform uplink transmission using the information on the transmit power for each channel. This can improve the flexibility in a communication system, for example.

[0471] Regarding the case where a plurality of transmit powers are provided for each base station of each NW, the above-described examples may be combined. For example, the transmit power for each uplink channel may vary depending on the presence or absence of NW preemption communication. This can improve the reliability of NW preemption communication and the flexibility in a communication system, for example.

[0472] According to the fourth embodiment, the power used for transmission from the UE to each base station can be appropriately adjusted.

[0473] The above-described embodiments and their modifications are merely examples, and the embodiments and their modifications can be freely combined. Also, any component of the embodiments and their modifications can be appropriately changed or omitted.

[0474] For example, in the above-described embodiments and their modifications, a subframe is an example of a time unit for communication in a fifth-generation base station communication system. It may also be a scheduling unit. In the above-described embodiments and their modifications, the processing described in terms of subframe units may be performed in terms of TTI units, slot units, sub-slot units, or mini-slot units.

[0475] Although the present disclosure has been described in detail, the above description is illustrative and not restrictive in all aspects. Numerous variations that are not illustrated can be understood to be possible.

Description of Reference Numerals

[0476] 200, 210 Communication system, 202 Communication terminal device, 203 Base station device.

Claims

1. A terminal device having a plurality of SIMs (Subscriber Identity Modules), the terminal device is configured to connect to a plurality of networks using the plurality of SIMs; the terminal device is configured to determine paging collisions between the plurality of networks; Terminal device.

2. the terminal device is configured to perform a procedure for avoiding the paging collision. The terminal device according to claim 1 .

3. The plurality of networks include a first network including an access and mobility management function (AMF) and a second network, The terminal device is configured to transmit, in the procedure, a first Non-Access Stream (NAS) signaling including information for avoiding the paging collision with the second network to the AMF; The terminal device according to claim 2.

4. The information includes identification information for identifying the terminal device. The terminal device according to claim 3.

5. The identification information is a 5G Globally Unique Temporary Identifier (5G-GUTI) assigned by the AMF, The terminal device according to claim 4.

6. The terminal device is configured to receive, in the procedure, from the AMF, a second NAS signaling including the identification information changed by the AMF; timing of paging by the first network is altered based on the altered identification information; The terminal device according to claim 4.

7. The terminal device is configured to send a third NAS signaling to the AMF in response to receiving the second NAS signaling, the third NAS signaling indicating completion of the procedure. The terminal device according to claim 6.

8. the plurality of networks includes a first network and a second network; The terminal device is configured to transmit, in the procedure, signaling including information for avoiding the paging collision with the second network to a base station device in the first network. The terminal device according to claim 2.

9. A communication system including a terminal device having a plurality of SIMs (Subscriber Identity Modules) and configured to connect to a plurality of networks using the plurality of SIMs, the terminal device is configured to determine paging collisions between the plurality of networks; Communication systems.

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