User equipment, node, and communication method

Abstract

To reduce the time it takes for wireless communication using a secondary cell group to become possible after the radio quality of the secondary cell group has improved in user equipment.SOLUTION: User equipment UE that uses dual connectivity to perform wireless communication with a master node MN and a secondary node SN in a mobile communication system includes: a receiving unit that receives information from the master node indicating radio quality conditions that should be met for the user equipment to perform activation processing for a secondary cell group of the secondary node; and a control unit that measures radio quality of the secondary cell group and evaluates whether the radio quality conditions have been met. The control unit performs the activation processing for the secondary cell group in response to the radio quality conditions being met.SELECTED DRAWING: Figure 9

Description

[Technical field]

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

[0002] The 3rd Generation Partnership Project (3GPP (registered trademark; hereinafter the same)), which is a standardization project for mobile communication systems, defines technical specifications for dual connectivity (DC). In DC, a user equipment (UE) performs wireless communication with a master cell group (MCG) of a master node (MN) and a secondary cell group (SCG) of a secondary node (SN).

[0003] In each of the MCG and SCG, multiple component carriers (CCs) corresponding to multiple serving cells are aggregated, and the UE can simultaneously receive or transmit using multiple CCs (multiple cells). The multiple CCs may be contiguous or non-contiguous in the frequency direction. One serving cell in each of the MCG and SCG is called a primary cell (PCell), and a set of serving cells is formed by configuring one or more secondary cells (SCells) in the UE together with the PCell. The PCell (SpCell) of the SCG is also called a PSCell.

[0004] Release 17 of the 3GPP standard introduces a specification for deactivating an SCG. Activating an SCG that has been set to a deactivated state is generally performed in the following procedure. First, the UE transmits a measurement report message including measurement results of the radio quality of each cell to the MN. Second, the MN instructs the UE to activate the SCG using a radio resource control (RRC) message based on the measurement report message. Third, the UE activates the SCG in response to the instruction. Activating the SCG transitions the SCG from a deactivated state to an activated state, enabling wireless communication using the SCG.

[0005] This type of control has a problem in that it is difficult to shorten the time from when the radio quality for the SCG improves in the UE until when radio communication using the SCG becomes possible. [Prior art documents] [Non-patent literature]

[0006] [Non-Patent Document 1] 3GPP Technical Specification: TS 38.300 V17.3.0 (2022-12) Summary of the Invention

[0007] A user equipment according to a first aspect is an equipment that performs wireless communication with a master node and a secondary node using dual connectivity in a mobile communication system. The user equipment includes a receiver that receives, from the master node, information indicating a wireless quality condition that should be satisfied in order for the user equipment to perform an activation process for a secondary cell group of the secondary node, and a controller that measures wireless quality for the secondary cell group and evaluates whether the wireless quality condition is satisfied. The controller executes the activation process for the secondary cell group in response to the wireless quality condition being satisfied.

[0008] A node according to a second aspect is a node that operates as the master node in a mobile communication system in which a user equipment performs wireless communication with a master node and a secondary node using dual connectivity. The node includes a control unit that sets a secondary cell group of the secondary node to the user equipment, and a transmission unit that transmits to the user equipment information indicating a wireless quality condition that should be satisfied for the user equipment to perform an activation process for the secondary cell group.

[0009] A communication method according to a third aspect is a method used in a user equipment that performs wireless communication with a node using carrier aggregation in a mobile communication system. The communication method includes a step of receiving, from the node, information indicating a wireless quality condition that should be satisfied for the user equipment to perform an activation process for a secondary cell group set in the user equipment, a step of measuring a wireless quality for the secondary cell group and evaluating whether the wireless quality condition is satisfied, and a step of performing the activation process for the secondary cell group in response to the wireless quality condition being satisfied.

[0010] A communication method according to a fourth aspect is a method used in a node that performs wireless communication with a user equipment using carrier aggregation in a mobile communication system, the communication method including the steps of: setting a secondary cell group in the user equipment; and transmitting, to the user equipment, information indicating a radio quality condition that should be satisfied for the user equipment to perform an activation process for the secondary cell group. [Brief description of the drawings]

[0011] [Figure 1] FIG. 1 is a diagram illustrating a configuration example of a mobile communication system according to an embodiment. [Diagram 2] FIG. 2 is a diagram illustrating an example of the configuration of a protocol stack of a U-plane radio interface that handles data. [Diagram 3] FIG. 2 is a diagram illustrating an example of the configuration of a protocol stack of a C-plane wireless interface that handles signaling (control signals). [Figure 4] 1 is a diagram for explaining a terahertz (THz) wave cell according to an embodiment. [Diagram 5] FIG. 2 is a diagram for explaining dual connectivity (DC) according to an embodiment. [Figure 6] FIG. 1 illustrates a general procedure for setting up and activating an SCG. [Figure 7]FIG. 2 is a diagram illustrating a configuration example of a UE (user equipment) according to the embodiment. [Figure 8] FIG. 2 is a diagram illustrating an example of the configuration of a node according to the embodiment. [Figure 9] FIG. 2 is a diagram illustrating an example of a system operation according to the first embodiment. [Figure 10] FIG. 1 is a diagram for explaining a bandwidth portion (BWP). [Figure 11] FIG. 11 is a diagram illustrating an example of a system operation according to the second embodiment. [Figure 12] FIG. 11 is a diagram illustrating an example of a system operation according to the third embodiment. [Figure 13] FIG. 13 is a diagram showing a specific example of a reference signal (Fast tracking RS) according to the fourth embodiment. [Figure 14] FIG. 13 is a diagram illustrating an example of a system operation according to the fourth embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Hereinafter, a mobile communication system according to an embodiment will be described with reference to the drawings. In the description of the drawings, the same or similar parts are denoted by the same or similar reference numerals.

[0013] (1) First embodiment The first embodiment will be described with reference to FIGS.

[0014] (1.1) System configuration example 1 is a diagram showing a configuration example of a mobile communication system according to an embodiment. The mobile communication system according to the embodiment is a system conforming to the 3GPP standard. For example, the mobile communication system according to the embodiment may be a fifth generation (5G) system or a sixth generation (6G) system.

[0015] The mobile communication system includes a network (NW) 1 and a user equipment (UE) 100. The UE 100 is a mobile communication device that performs wireless communication with the NW 1. The UE 100 may be any device used by a user, and may be, for example, a mobile phone terminal (including a smartphone), a tablet terminal, a notebook PC (Personal Computer), a communication module (including a communication card or a chipset), a sensor or a device provided in a sensor, a vehicle or a device provided in a vehicle (Vehicle UE), or an aircraft or a device provided in an aircraft (Aerial UE).

[0016] The NW1 includes a radio access network (RAN) 10 and a core network (CN) 20. When the mobile communication system is a 5th generation system (5GS: 5th Generation System), the RAN 10 is referred to as a Next Generation Radio Access Network (NG-RAN), and the CN 20 is referred to as a 5G Core Network (5GC).

[0017] The RAN 10 includes a plurality of nodes 200 (nodes 200a to 200c in the illustrated example). The nodes 200 are connected to each other via inter-node interfaces. The nodes 200 are also referred to as base stations. The nodes 200 are configured (i.e., functionally divided) with a CU (Central Unit) and a DU (Distributed Unit), and both units may be connected by a fronthaul interface. When the mobile communication system is 5GS, the nodes 200 are referred to as gNBs, the inter-node interface is referred to as an Xn interface, and the fronthaul interface is referred to as an F1 interface.

[0018] Each node 200 manages one or more cells. The node 200 performs wireless communication with the UE 100 that has established a connection with its own cell. Each node 200 has a radio resource management (RRM) function, a routing function for user data (also simply referred to as "data"), a measurement control function for mobility control and scheduling, and the like. Note that "cell" is used as a term indicating the smallest unit of a wireless communication area. "Cell" is also used as a term indicating a function or resource for performing wireless communication with the UE 100. One cell belongs to one carrier frequency (also simply referred to as "frequency").

[0019] The CN 20 includes a CN device 300. The CN device 300 may include a C-plane device corresponding to a control plane (C-plane) and a U-plane device corresponding to a user plane (U-plane). The C-plane device performs various mobility controls and paging for the UE 100. The C-plane device communicates with the UE 100 using NAS (Non-Access Stratum) signaling. The U-plane device performs data transfer control. When the mobile communication system is 5GS, the C-plane device is called an AMF (Access and Mobility Management Function), the U-plane device is called a UPF (User Plane Function), and the interface between the node 200 and the CN device 300 is called an NG interface.

[0020] FIG. 2 is a diagram showing an example of the configuration of a protocol stack of a U-plane radio interface that handles data.

[0021] The U-plane radio interface protocol includes, for example, a physical (PHY) layer, a medium access control (MAC) layer, a radio link control (RLC) layer, a packet data convergence protocol (PDCP) layer, and a service data adaptation protocol (SDAP) layer.

[0022] The PHY layer performs coding / decoding, modulation / demodulation, antenna mapping / demapping, and resource mapping / demapping. Data and control information are transmitted between the PHY layer of the UE 100 and the PHY layer of the node 200 via a physical channel. The PHY layer of the UE 100 receives downlink control information (DCI) transmitted from the node 200 on a physical downlink control channel (PDCCH). Specifically, the UE 100 performs blind decoding of the PDCCH using a radio network temporary identifier (RNTI) and acquires the successfully decoded DCI as the DCI addressed to the UE. The DCI transmitted from the node 200 has CRC parity bits scrambled by the RNTI added thereto.

[0023] The MAC layer performs data priority control and retransmission processing using hybrid ARQ (HARQ), etc. Data and control information are transmitted between the MAC layer of the UE 100 and the MAC layer of the node 200 via a transport channel. The MAC layer of the node 200 includes a scheduler. The scheduler determines the uplink and downlink transport format (transport block size, modulation and coding scheme (MCS)) and the resources to be allocated to the UE 100.

[0024] The RLC layer transmits data to the RLC layer on the receiving side by using the functions of the MAC layer and the PHY layer. Data and control information are transmitted between the RLC layer of the UE 100 and the RLC layer of the node 200 via logical channels.

[0025] The PDCP layer performs header compression / decompression, encryption / decryption, etc.

[0026] The SDAP layer performs mapping between an IP flow, which is a unit for QoS control by the CN 20, and a radio bearer, which is a unit for QoS control by an AS (Access Stratum). Note that if the RAN is connected to the EPC, the SDAP may not be required.

[0027] FIG. 3 is a diagram showing an example of the configuration of a protocol stack of a C-plane wireless interface that handles signaling (control signals).

[0028] The protocol stack of the C-plane radio interface has, for example, a Radio Resource Control (RRC) layer and a Non-Access Stratum (NAS) layer instead of the SDAP layer shown in FIG.

[0029] Between the RRC layer of the UE 100 and the RRC layer of the node 200, RRC signaling for various settings is transmitted. The RRC layer controls logical channels, transport channels, and physical channels in response to establishment, re-establishment, and release of radio bearers. When there is a connection (RRC connection) between the RRC of the UE 100 and the RRC of the node 200, the UE 100 is in an RRC connected state. When there is no connection (RRC connection) between the RRC of the UE 100 and the RRC of the node 200, the UE 100 is in an RRC idle state. When the connection between the RRC of the UE 100 and the RRC of the node 200 is suspended, the UE 100 is in an RRC inactive state.

[0030] The NAS layer (also simply referred to as "NAS") located above the RRC layer performs session management, mobility management, etc. NAS signaling is transmitted between the NAS layer of UE 100 and the NAS layer of CN device 300. Note that UE 100 has an application layer and the like in addition to the radio interface protocol. Also, the layer below the NAS layer is referred to as the AS layer (also simply referred to as "AS").

[0031] (1.2) DC using a terahertz wave cell FIG. 4 is a diagram for explaining a terahertz (THz) wave cell according to an embodiment.

[0032] The mobile communication system according to the embodiment may be a 6G system. In 6G, it is expected that terahertz (THz) waves will be utilized. A cell operated by THz waves is called a THz wave cell. Compared with millimeter waves (mmW), THz waves have a stronger tendency to travel in a straight line, have a higher free space loss, and are more susceptible to the effects of the atmosphere and precipitation. Therefore, the THz wave cell may be an ultra-small cell.

[0033] In the illustrated example, the diameter of the coverage area of ​​the THz wave cell is about 10 [m], the diameter of the coverage area of ​​the mmW cell operated at mmW is about 100 [m], and the diameter of the coverage area of ​​the macro cell is about 1000 [m]. Under such assumptions, for example, UE 100 moving at 60 [km / s] passes through the coverage area of ​​each THz wave cell in about 599 [ms].

[0034] Dual connectivity (DC) is one method for stably controlling small cells in a mobile communication system. FIG. 5 is a diagram for explaining dual connectivity (DC) according to an embodiment. In the embodiment, it is assumed that a THz-wave cell is used as a cell of a secondary cell group (SCG). Furthermore, a THz-wave cell may be used as a secondary cell (SCell) of a master cell group (MCG). However, a mmW cell may be used instead of the THz-wave cell.

[0035] A DC may be set for the UE 100 in the RRC connected state. In the DC, the UE 100 performs radio communication with a master cell group (MCG) managed by a master node (MN) 200M and a secondary cell group (SCG) managed by a secondary node (SN). The MN 200M and the SN 200S are connected to each other via an inter-node interface. When the MN 200M and the SN 200S are not distinguished from each other, they are simply referred to as the node 200. When the MN 200M is a 5G / NR node, it is also referred to as a master gNB (MgNB). When the SN 200M is a 5G / NR node, it is also referred to as a secondary gNB (SgNB).

[0036] For example, the MN 200M transmits a predetermined message (e.g., an SN Addition Request message) to the SN 200S, and the MN 200M transmits an RRC Reconfiguration message to the UE 100, whereby the SCG is set in the UE 100 and DC is started. In the DC, the UE 100 in the RRC connected state is assigned radio resources by the respective schedulers of the MN 200M and the SN 200S, and performs radio communication using the radio resources of the MN 200M and the radio resources of the SN 200S.

[0037] The MN 200M may have a control plane connection with the CN 20. The MN 200M provides the main radio resources of the UE 100. The MN 200M manages the MCG, which is a group of serving cells associated with the MN 200M. The MCG has a primary cell (PCell) and optionally has one or more secondary cells (SCells). On the other hand, the SN 200S may not have a control plane connection with the CN 20. The SN 200S provides additional radio resources to the UE 100. The SN 200S manages the SCG, which is a group of serving cells associated with the SN 200S. The SCG has a primary / secondary cell (PSCell) and optionally has one or more SCells. The PCell of the MCG 201M and the PSCell of the SCG 201S may be referred to as a special cell (SpCell).

[0038] The mobile communication system supports activation and deactivation of the SCG to enable reduction of power consumption of the UE 100 in which the DC is set. The activation / deactivation of the SCG can be instructed by an RRC reconfiguration message from the MN 200M to the UE 100. While the SCG is deactivated, all SCG SCells are in an inactive state. While the SCG is deactivated, the UE 100 does not need to transmit a physical uplink shared channel (PUSCH), a sounding reference signal (SRS), and a channel quality indicator (CSI) report in the SCG, and while the SCG is deactivated, the UE 100 does not need to monitor a physical downlink shared channel (PDCCH) or receive a downlink shared channel (DL-SCH) in the SCG. However, the UE 100 can continue radio link monitoring (RLM) and measurement reports for the PSCell. When activating the SCG, the UE 100 may skip the random access procedure if the timing advance (TA) with the PSCell is valid.

[0039] FIG. 6 illustrates the general procedure for setting up and activating an SCG.

[0040] In step S11, the UE 100 transmits a Measurement Report message including a measurement result of the radio quality of each cell to the MN 200M. The radio quality is, for example, at least one of RSRP (Reference Signal Received Power), RSRQ (Reference Signal Received Quality), and SINR (Signal to Interference & Noise Ratio). The Measurement Report message is an RRC message transmitted and received in the RRC layer. The Measurement Report message may be transmitted periodically or may be event-triggered. The MN 200M receives the Measurement Report message. The MN 200M decides to set an SCG for the UE 100 based on the Measurement Report message.

[0041] In step S12, the MN 200M may send an SN (S-Node) Addition Request message to the SN 200S to request preparation of resources for DC operation for the UE 100.

[0042] In step S13, in response to receiving the SN Addition Request message, the SN 200S may send an SN (S-Node) Addition Request Ack (Acknowledge) message to the MN 200M to acknowledge the preparation of resources for DC operation for the UE 100.

[0043] In step S14, the MN 200M transmits an RRC Reconfiguration message to the UE 100 for setting an SCG in the UE 100. The RRC Reconfiguration message is an RRC message transmitted and received in the RRC layer. The UE 100 receives the RRC Reconfiguration message. Here, it is assumed that the initial state of the SCG is an inactive state.

[0044] In step S15, the UE 100 transmits an RRC Reconfiguration Complete message indicating that the setting (addition) of the SCG based on the RRC Reconfiguration message has been completed to the MN 200M. The RRC Reconfiguration Complete message is an RRC message transmitted and received at the RRC layer. The MN 200M receives the RRC Reconfiguration Complete message.

[0045] It is assumed that the wireless quality of the SCG (PSCell) improves in the UE 100 thereafter, and the wireless quality of the SCG (PSCell) becomes capable of communication.

[0046] In step S16, the UE 100 transmits a Measurement Report message including a measurement result of the radio quality of the PSCell to the MN 200M. The UE 100 may transmit the Measurement Report message to the MN 200M when the radio quality of the PSCell improves as a trigger. The MN 200M receives the Measurement Report message.

[0047] In step S17, the MN 200M transmits an RRC Reconfiguration message for activating the SCG to the UE 100. The UE 100 receives the RRC Reconfiguration message and starts activating the SCG. The SCG activation process includes communication preparation such as channel state information (CSI) measurement, automatic gain control (AGC), and beam management.

[0048] In step S18, the UE 100 transmits an RRC Reconfiguration Complete message to the MN 200M. The MN 200M receives the RRC Reconfiguration Complete message.

[0049] In step S19, the UE 100 starts wireless communication (data communication) with the SN 200S using the activated SCG.

[0050] According to such a procedure, it takes a long time for the UE 100 to be able to use the SCG (PSCell) after the radio quality of the SCG becomes communicable. If the cell of the SCG is a THz wave cell, the coverage area of ​​the cell becomes even narrower due to the influence of shielding, etc., so the time during which the SCG is available is short. Therefore, the procedure of FIG. 6 has a problem in that the time during which data can actually be transmitted and received on the SCG is shortened because it takes a long time to complete activation of the SCG.

[0051] Meanwhile, in Release 17 of the 3GPP standard, a specification of Conditional PSCell Addition (CPA) is introduced. In CPA, the MN 200M sets a candidate cell of the PSCell and an execution condition for adding the candidate cell in the UE 100, and when the execution condition is satisfied, the UE 100 adds the candidate cell as a PSCell. This enables SN addition to be performed quickly. However, in CPA, additional processing is required to add an SCell of an SCG after adding a PSCell, and it still takes a long time to set multiple serving cells as an SCG. In addition, in CPA, when an SCG (PSCell) has already been set and is in an inactive state, an RRC Reconfiguration message needs to be transmitted from the MN 200M to activate it. In addition, in order for the MN 200M to transmit this RRC Reconfiguration message, it is necessary for the MN 200M to know the radio state of the SCG by a Measurement Report message from the UE 100. In contrast, according to the conditional SCG activation according to this embodiment, it is possible to eliminate delays caused by transmitting and receiving measurement report messages and RRC Reconfiguration messages.

[0052] Although it is possible to eliminate delays in activating the SCG by setting the SCG in advance and maintaining the SCG in an active state, there is a problem in that the power consumption of the UE 100 increases. Therefore, a method is desired that can deactivate the SCG when the radio quality of the SCG (PSCell) does not satisfy a predetermined quality, and quickly activate the SCG when the radio quality of the SCG (PSCell) satisfies the predetermined quality. In the following first embodiment, a method and operation that can shorten the time required for activating the SCG will be mainly described.

[0053] (1.3) Example of user device configuration FIG. 7 is a diagram illustrating a configuration example of a UE 100 (user equipment) according to the embodiment.

[0054] The UE 100 includes a receiving unit 110, a transmitting unit 120, and a control unit 130. The receiving unit 110 and the transmitting unit 120 configure a wireless communication unit 140 that performs wireless communication with the node 200.

[0055] The receiving unit 110 performs various receptions under the control of the control unit 130. The receiving unit 110 includes an antenna and a receiver. The receiver converts a radio signal received by the antenna into a baseband signal (received signal) and outputs the signal to the control unit 130. The transmitting unit 120 performs various transmissions under the control of the control unit 130. The transmitting unit 120 includes an antenna and a transmitter. The transmitter converts a baseband signal (transmitted signal) output by the control unit 130 into a radio signal and transmits the signal from the antenna.

[0056] The control unit 130 performs various controls and processes in the UE 100. The above and below described operations of the UE 100 may be operations under the control of the control unit 230. The control unit 130 includes at least one processor and at least one memory. The memory stores programs executed by the processor and information used in the processing by the processor. The processor may include a baseband processor and a CPU (Central Processing Unit). The baseband processor performs modulation / demodulation and encoding / decoding of baseband signals. The CPU executes programs stored in the memory to perform various processes.

[0057] The UE 100 configured in this manner performs wireless communication with the MN 200M and the SN 200S using the DC. The receiver 110 receives information indicating a wireless quality condition that should be satisfied for the UE 100 to execute an activation process for the SCG of the SN 200S from the MN 200M. The controller 130 measures the wireless quality of the SCG (PSCell) and evaluates whether the wireless quality condition is satisfied. Then, the controller 130 executes an activation process for the SCG in response to the wireless quality condition being satisfied. In the first embodiment, the activation process includes a process of transitioning an SCG in an inactive state to an active state. Thereby, the UE 100 can autonomously execute an activation process for the SCG when the wireless quality of the SCG (PSCell) satisfies the wireless quality condition (predetermined quality). Therefore, it is possible to speed up the activation of the SCG.

[0058] The activation process may include a process of leaving a bandwidth portion (BWP) in a dormant state in a PSCell that is a primary cell of the SCG. An example of using a dormant BWP will be described in a second embodiment.

[0059] In the embodiment, in response to the wireless quality condition being satisfied, the transmission unit 120 transmits a notification regarding the activation process to the node 200. This allows the node 200 to know that the UE 100 will perform the activation process based on the notification. Therefore, wireless communication using the activated SCG can be started smoothly.

[0060] (1.4) Node configuration example 8 is a diagram showing a configuration example of a node 200 (base station) according to an embodiment. The node 200 may be an MN 200M or an SN 200S.

[0061] The node 200 includes a transmitting unit 210, a receiving unit 220, a control unit 230, and a NW communication unit 240. The transmitting unit 210 and the receiving unit 220 configure a wireless communication unit 250 that performs wireless communication with the UE 100.

[0062] The transmitting unit 210 performs various transmissions under the control of the control unit 230. The transmitting unit 210 includes an antenna and a transmitter. The transmitter converts a baseband signal (transmission signal) output by the control unit 230 into a radio signal and transmits it from the antenna. The receiving unit 220 performs various receptions under the control of the control unit 230. The receiving unit 220 includes an antenna and a receiver. The receiver converts a radio signal received by the antenna into a baseband signal (reception signal) and outputs it to the control unit 230.

[0063] The control unit 230 performs various controls and processes in the node 200. The operations of the node 200 described above and below may be operations under the control of the control unit 230. The control unit 230 includes at least one processor and at least one memory. The memory stores programs executed by the processor and information used in the processing by the processor. The processor may include a baseband processor and a CPU. The baseband processor performs modulation / demodulation and encoding / decoding of baseband signals. The CPU executes programs stored in the memory to perform various processes.

[0064] The NW communication unit 240 is connected to adjacent nodes via an inter-node interface. The NW communication unit 240 is connected to the CN device 300 via a node-CN interface.

[0065] The node 200 configured in this manner operates as the MN 200M in a mobile communication system in which the UE 100 performs wireless communication with the MN 200M and the SN 200S using the DC. The control unit 230 sets the SCG of the SN 200S to the UE 100. The transmission unit 210 transmits, to the UE 100, information indicating a wireless quality condition that should be satisfied for the UE 100 to execute an activation process for the SCG. This allows the UE 100 to autonomously perform an activation process for the SCG when the wireless quality for the SCG satisfies the wireless quality condition (predetermined quality).

[0066] In the embodiment, the receiver 220 receives a notification regarding the activation process from the UE 100 in response to the wireless quality condition being satisfied in the UE 100. This allows the node 200 (MN 200M) to know that the UE 100 will perform the activation process based on the notification.

[0067] (1.5) System operation example Fig. 9 is a diagram showing an example of the system operation according to the first embodiment. In Fig. 9, non-essential steps are indicated by dashed lines. Also, duplicated explanations of operations similar to those in Fig. 6 will be omitted.

[0068] In step S101, the MN 200M may send an SN Addition Request message to the SN 200S to request preparation of resources for DC operation for the UE 100.

[0069] In step S102, in response to receiving the SN Addition Request message, the SN 200S may send an SN Addition Request Ack message to the MN 200M to acknowledge the preparation of resources for DC operation for the UE 100.

[0070] In step S103, the UE 100 may receive a reference signal from each cell, measure radio quality based on the reference signal, and transmit a Measurement Report message including the measurement result to the MN 200M. Here, the Measurement Report message includes the measurement result of the THz wave cell. The receiving unit 220 of the MN 200M receives the Measurement Report message.

[0071] In step S104, the MN 200M may transmit a message (e.g., an SN Modification Request message) to the SN 200S to request deactivation of the SCG and to set conditional SCG activation in the UE 100. The SN 200S receives the message. The message may include an identifier of the UE 100, specifically, an identifier for identifying the UE 100 on the inter-node interface. The message may include information notifying that the SCG is conditional or information requesting the setting of the conditional SCG activation. When the SN 200S requests the setting of the conditional SCG activation, the SN 200S may include setting information for the conditional SCG activation in the message.

[0072] In step S105, the SN 200S may transmit a message (e.g., an SN Modification Request Ack message) indicating approval of the message in step S104 to the MN 200M. The MN 200M receives the message. The message may include information on resources (e.g., SCG and bearer) prepared by the SN 200S, such as information on the PSCell and information on the SCell of the SCG. The message may include setting information on a reference signal of the SCG (PSCell). These pieces of information may be transmitted from the MN 200M to the UE 100 in step S106.

[0073] In step S106, the MN 200M generates an RRC Reconfiguration message and transmits the RRC Reconfiguration message to the UE 100. The UE 100 receives the RRC Reconfiguration message. The RRC Reconfiguration message includes information for configuring an SCG and configuration information for conditional SCG activation. The information for configuring an SCG includes information on a PSCell and information on an SCell of the SCG. The configuration information for conditional SCell activation includes information indicating a radio quality condition that should be satisfied for the UE 100 to activate a corresponding SCG. The information indicating the radio quality condition may include at least one radio quality threshold among an RSRP threshold, an RSRQ threshold, and an SINR threshold.

[0074] In the first embodiment, an initial state of the SCG set in the UE 100 is a deactivated state. The UE 100 starts radio quality measurement for the SCG (specifically, the PSCell) based on configuration information for conditional SCG activation.

[0075] In step S107, the UE 100 generates an RRC Reconfiguration Complete message and transmits the RRC Reconfiguration Complete message to the MN 200M. The MN 200M receives the RRC Reconfiguration Complete message.

[0076] In step S108, the UE 100 receives a reference signal of the PSCell and measures the radio quality of the PSCell based on the reference signal. The reference signal of the PSCell may be a demodulation reference signal (DMRS) included in an SSB (SS / PBCH Block) transmitted by the PSCell, or may be a tracking reference signal (TRS), which is a type of CSI-RS.

[0077] In step S109, UE 100 determines whether the radio quality condition set in step S106 is satisfied. Specifically, UE 100 compares the measurement result (RSRP, RSRQ, and / or SINR) of step S108 with the radio quality threshold set in step S106, and determines that the radio quality condition is satisfied if the measurement result exceeds the radio quality threshold. If it is determined that the radio quality condition is not satisfied (step S109: NO), the process returns to step S108.

[0078] On the other hand, when it is determined that the radio quality condition is satisfied (step S109: YES), in step S110, UE 100 autonomously starts activation of the SCG. Here, UE 100 may perform control for establishing time / frequency synchronization with each cell of the SCG. For example, UE 100 receives SSB or TRS of each cell of the SCG, and establishes time / frequency synchronization using the SSB or TRS. In addition, UE 100 may perform CSI measurement, AGC, and beam management for each cell of the SCG.

[0079] In addition, in steps S108 and S110, the SN 200S may transmit the TRS on the PSCell at a timing (opportunity) that the MN 200M has set in advance in the UE 100, and the UE 100 may wake up at the timing and receive the TRS. Information on the timing (opportunity) may be included in the RRC setting in step S106.

[0080] In step S111, the UE 100 triggers the transmission of an SCG activation notification and transmits the SCG activation notification to the MN 200M. The SCG activation notification may be a newly introduced MAC CE. Alternatively, the SCG activation notification may be a notification included in the UCI transmitted by the PUCCH, may be a PDCP Control PDU, or may be a notification included in the RRC message. The MN 200M receives the SCG activation notification. In response to receiving the SCG activation notification, the MN 200M recognizes that the SCG of the UE 100 has become available. The SCG activation notification may include an index (which may be a cell ID) of each cell of the activated SCG. The index may refer to each entry of the cell list of the SCG set in the RRC Reconfiguration message in step S106.

[0081] Prior to the transmission of the SCG activation notification, the following processing may be performed in the PHY layer and the MAC layer. Specifically, UE 100 transmits a Scheduling Request (SR) to MN 200M, MN 200M transmits a UL grant for a Buffer Status Report (BSR) to UE 100, UE 100 transmits a BSR to MN 200M, and MN 200M transmits a UL grant for PUSCH transmission to UE 100. Then, UE 100 transmits the SCG activation notification based on the UL grant for PUSCH transmission.

[0082] In step S112, the MN 200M may transmit a message (for example, an SN Modification Request message) to the SN 200S to notify that the UE 100 has activated the SCG. The SN 200S receives the message. The message may include an identifier of the UE 100, specifically, an identifier for identifying the UE 100 on the node-to-node interface.

[0083] In step S113, the SN 200S may transmit a message indicating approval for the message in step S112 (for example, an SN Modification Request Ack message) to the MN 200M. The MN 200M receives the message.

[0084] In step S114, the UE 100 starts wireless communication (data communication) with the SN 200S using the activated SCG. Here, the SN 200S performs DL transmission and / or UL grant to the UE 100 in each cell of the activated SCG, and performs wireless communication (data communication) on the SCG.

[0085] In this operation example, an example in which the UE 100 transmits an SCG activation notification to the MN 200M has been described, but if the SCG activation has been completed, the SCG activation notification may be transmitted to the MN 200M on the SCG (for example, a PSCell).

[0086] In this operation example, the MN 200M transmits a message for setting conditional SCG activation to the UE 100 to the SN 200S, and the SN 200S transmits a response message to the message. On the other hand, the SN 200S may autonomously transmit a message for setting conditional SCG activation to the UE 100 to the MN 200M. In this case, the message may include information notifying that the conditional SCG activation is performed or information requesting the setting of the conditional SCG activation. When the SN 200S requests the setting of the conditional SCG activation, the SN 200S may include setting information for the conditional SCG activation in the message.

[0087] (2) Second embodiment The second embodiment will be described with reference to Figs. 10 and 11, focusing mainly on the differences from the first embodiment.

[0088] (2.1) BWP FIG. 10 is a diagram for explaining the BWP.

[0089] Bandwidth Adaptation (BA) allows the transmission and reception bandwidth of the UE 100 to be adjusted without being required to be as large as the bandwidth of the cell. A part of the cell bandwidth is called BWP. In BA, the node 200 configures one or more BWPs for the UE 100 in the cell and notifies the UE 100 which of the configured BWPs is currently active. There are two types of BWPs: an initial BWP used for initial access and a dedicated BWP that is individually configured for the UE 100. The bandwidth and subcarrier spacing of each BWP can be variably configured.

[0090] In the illustrated example, three different BWPs are configured in the UE 100, and an example is shown in which the active BWP is switched between these BWPs. BWP1 has a width of 40 [MHz] and a subcarrier spacing of 15 [kHz], BWP2 has a width of 10 MHz and a subcarrier spacing of 15 kHz, and BWP3 has a width of 20 MHz and a subcarrier spacing of 60 kHz.

[0091] In each of the UL and DL, there is only one BWP in an active state, and the rest are in an inactive state. In the inactive BWP, the UE 100 does not monitor the PDCCH, and does not transmit the PUCCH, the PRACH, and the UL-SCH.

[0092] In the current 3GPP technical specifications, in the case of carrier aggregation (CA), the node 200 can configure a BWP in a dormant state for the SCell. If the active BWP of the activated SCell is a BWP in a dormant state, the UE 100 stops PDCCH monitoring and SRS / PUSCH / PUCCH transmission on the SCell, but continues to perform CSI measurement, AGC, and beam management. PDCCH / DCI is used to control entering and leaving the dormant BWP for the SCell. Note that the dormant BWP is one of the dedicated BWPs of the UE 100 configured by the node 200 via dedicated RRC signaling.

[0093] In the second embodiment, a case is assumed in which a dormant BWP can be set in a PSCell.

[0094] (2.2) System operation example The UE 100 according to the second embodiment performs wireless communication with the MN 200M and the SN 200S using the DC, as in the first embodiment. In the second embodiment, the activation process for the SCG includes a dormant exit process for switching a BWP in a dormant state in the PSCell to a non-dormant state. Specifically, according to the second embodiment, the UE 100 exits the dormant state for the BWP in the dormant state in the PSCell in the active state in response to the wireless quality condition set by the MN 200M being satisfied.

[0095] Fig. 11 is a diagram showing an example of system operation according to the second embodiment. In Fig. 11, non-essential steps are indicated by dashed lines. Also, duplicated explanations of operations similar to those in the first embodiment will be omitted.

[0096] The operations from step S201 to step S205 are similar to those in the first embodiment described above (FIG. 9).

[0097] In step S206, the MN 200M transmits an RRC Reconfiguration message to the UE 100. The UE 100 receives the RRC Reconfiguration message. In the second embodiment, the RRC Reconfiguration message includes information for setting an SCG, information for setting a dormant BWP in the PSCell, and configuration information for leaving the conditional dormant BWP. The configuration information for leaving the conditional dormant BWP includes information indicating a radio quality condition that should be satisfied to end (leave) the dormant state of the BWP when the active BWP of the corresponding active state PSCell is a dormant BWP. The information indicating the radio quality condition may include at least one radio quality threshold of an RSRP threshold, an RSRQ threshold, and an SINR threshold.

[0098] In the second embodiment, the initial state of the active BWP of the PSCell configured in the UE 100 is a dormant state. The UE 100 starts radio quality measurement for the PSCell based on configuration information for conditional dormant BWP departure. When the active BWP of the PSCell is a dormant BWP, the UE 100 may autonomously deactivate the SCell of the SCG.

[0099] In step S207, the UE 100 transmits an RRC Reconfiguration Complete message to the MN 200M. The MN 200M receives the RRC Reconfiguration Complete message.

[0100] In step S208, the UE 100 receives a reference signal of the PSCell, and measures the radio quality of the PSCell based on the reference signal.

[0101] In step S209, the UE 100 determines whether the radio quality condition set in step S206 is satisfied. Specifically, the UE 100 compares the measurement result (RSRP, RSRQ, and / or SINR) of step S208 with the radio quality threshold set in step S206, and determines that the radio quality condition is satisfied if the measurement result exceeds the radio quality threshold. If it is determined that the radio quality condition is not satisfied (step S209: NO), the process returns to step S208.

[0102] On the other hand, when it is determined that the radio quality condition is satisfied (step S209: YES), in step S210, UE 100 autonomously ends (leaves) the dormant BWP of the PSCell (i.e., switches the active BWP of the PSCell to a non-dormant state). UE 100 may leave the dormant state for the active BWP of the PSCell and autonomously activate the SCell of the SCG.

[0103] In step S211, the UE 100 triggers transmission of a PSCell BWP dormant leaving notification, and transmits the PSCell BWP dormant leaving notification to the MN 200M. The MN 200M receives the PSCell BWP dormant leaving notification. The PSCell BWP dormant leaving notification may be a newly introduced MAC CE. Alternatively, the PSCell BWP dormant leaving notification may be a notification included in UCI transmitted by a PUCCH, may be a PDCP Control PDU, or may be a notification included in an RRC message.

[0104] Prior to transmission of a PSCell BWP sleep leave notification, the following processing may be performed in the PHY layer and the MAC layer. Specifically, an SR is transmitted from UE 100 to MN 200M, a UL grant for BSR is transmitted from MN 200M to UE 100, a BSR is transmitted from UE 100 to MN 200M, and a UL grant for PUSCH transmission is transmitted from MN 200M to UE 100. Then, UE 100 transmits a PSCell BWP sleep leave notification based on the UL grant for PUSCH transmission.

[0105] In step S212, the MN 200M may transmit a message (for example, an SN Modification Request message) to the SN 200S to notify that the UE 100 has left the dormant state for the active BWP of the PSCell. The SN 200S receives the message. The message may include an identifier of the UE 100, specifically, an identifier for identifying the UE 100 on the node-to-node interface.

[0106] In step S213, the SN 200S may transmit a message indicating approval for the message in step S212 (for example, an SN Modification Request Ack message) to the MN 200M. The MN 200M receives the message.

[0107] In step S214, the UE 100 starts wireless communication (data communication) with the SN 200S using the active BWP of the PSCell (and the SCell of the SCG). Here, the SN 200S performs DL transmission and / or UL grant to the UE 100 in each cell of the SCG including the PSCell, and performs wireless communication (data communication) on the SCG.

[0108] In this operation example, an example has been described in which the UE 100 transmits a PSCell BWP dormant leaving notification to the MN 200M, but the PSCell BWP dormant leaving notification may be transmitted to the SN 200S on the PSCell.

[0109] (3) Third embodiment The third embodiment will be described with reference to Fig. 12, focusing mainly on the differences from the above-mentioned embodiments. The third embodiment is an embodiment based on the above-mentioned first embodiment. However, the third embodiment may be an embodiment based on the above-mentioned second embodiment.

[0110] In the third embodiment, UE100 completes SCG activation (i.e., makes the SCG available for data communication) within a predetermined time from the timing of transmitting an SCG activation notification or the timing of receiving an acknowledgment (HARQ ACK) to the SCG activation notification from MN200M. Meanwhile, MN200M considers activation processing to be completed within a predetermined time from the timing of receiving an SCG activation notification or the timing of transmitting an acknowledgment (HARQ ACK) to the SCG activation notification to UE100. This allows MN200M to smoothly start data communication on the SCG after completing SCG activation.

[0111] In the third embodiment, the transmitting unit 120 of the UE 100 may transmit information indicating the predetermined time to the MN 200M when transmitting the SCG activation notification or before transmitting the SCG activation notification. The receiving unit 220 of the MN 200M receives the information indicating the predetermined time from the UE 100. This allows the MN 200M to properly grasp the timing at which the UE 100 completes the activation of the SCG, and to smoothly start data communication on the SCG. Hereinafter, the predetermined time is also referred to as a "time offset."

[0112] Fig. 12 is a diagram showing an example of a system operation according to the third embodiment. In Fig. 12, non-essential steps are indicated by dashed lines. Also, duplicated explanations of operations similar to those in the first embodiment will be omitted.

[0113] The operations from step S301 to step S305 are similar to those in the first embodiment described above (FIG. 9).

[0114] In step S306, the MN 200M transmits an RRC Reconfiguration message to the UE 100. The receiving unit 110 of the UE 100 receives the RRC Reconfiguration message.

[0115] In the third embodiment, the RRC Reconfiguration message may include, in addition to the information described in the first embodiment, setting information for setting a time offset from the time of transmitting an SCG activation notification (or a positive response to the notification) to the completion of the SCG activation process. The time offset may be in milliseconds (e.g., X [ms]) or in units according to the radio frame configuration (e.g., X frames, X subframes, X slots, X OFDM symbols).

[0116] The operations from step S307 to step S310 are similar to those in the first embodiment described above (FIG. 9).

[0117] In step S311, the UE 100 transmits an SCG activation notification to the MN 200M. The receiving unit 220 of the MN 200M receives the SCG activation notification.

[0118] In the third embodiment, the SCG activation notification may include information indicating a time offset. The UE 100 determines how much time is required until the SCG activation is completed at the transmission timing of the SCG activation notification, and notifies the MN 200M of the time as a time offset.

[0119] Alternatively, the UE 100 may notify the network 1 in advance of information indicating a time offset determined according to the capability of the UE 100. For example, the MN 200M transmits an inquiry message (UE Capability Enquiry message) for inquiring about the capability of the UE 100 to the UE 100. In response to receiving the UE Capability Enquiry message, the UE 100 transmits a UE capability information message (UE capability information message) including the time offset information to the MN 200M.

[0120] The MN 200M recognizes that the SCG of the UE 100 becomes available after a time offset from the timing of receiving the SCG activation notification or the timing of transmitting the HARQ ACK for the SCG activation notification. The time offset may be a variable time offset set in step S306, a variable time offset notified in step S311, or a fixed time offset predefined in the 3GPP technical specifications.

[0121] The operations from step S312 to step S314 are similar to those in the first embodiment described above (FIG. 9).

[0122] (4) Fourth embodiment The fourth embodiment will be described with reference to Fig. 13 and Fig. 14, focusing mainly on the differences from the above-mentioned embodiments. The fourth embodiment is an embodiment based on the above-mentioned first embodiment. However, the fourth embodiment may be an embodiment based on the above-mentioned second embodiment.

[0123] In the above embodiment, the UE 100 detects that the radio quality of the PSCell satisfies a predetermined quality and performs SCG activation or dormant BWP withdrawal. Here, in order to quickly detect that the radio quality of the PSCell satisfies a predetermined quality, it is desirable that the UE 100 can constantly measure the radio quality of the PSCell. In the above embodiment, the UE 100 measures the radio quality (RSRP, etc.) using the SSB or TRS (CSI-RS) as a reference signal, but these reference signals are transmitted discretely in time. Therefore, at the timing when the SSB or CSI-RS is not transmitted, the UE 100 cannot measure the radio communication, and a delay may occur when detecting that the radio quality of the PSCell satisfies a predetermined quality.

[0124] Furthermore, when UE 100 activates SCG, UE 100 establishes time / frequency synchronization using SSB or TRS (CSI-RS) as a reference signal, and performs processes such as CSI measurement, AGC, and beam management. Therefore, when SSB or CSI-RS is not being transmitted, UE 100 cannot perform processes for SCG activation, and a delay may occur when activating SCG.

[0125] Therefore, in the fourth embodiment, the SN 200S continuously transmits a reference signal (also referred to as "Fast tracking RS") used for measuring radio quality on the PSCell in the time direction. The SN 200S may transmit the Fast tracking RS based on a request and / or setting from the MN 200M. The UE 100 receives the Fast tracking RS continuously transmitted in the time direction on the PSCell. The UE 100 measures the radio quality of the PSCell based on the Fast tracking RS. The UE 100 may also perform a process for SCG activation (for example, at least one of establishment of time / frequency synchronization, CSI measurement, AGC, and beam management) based on the Fast tracking RS. This makes it possible to suppress the above-mentioned delay.

[0126] 13 is a diagram showing a specific example of a fast tracking RS according to the fourth embodiment. In the fast tracking RS according to the fourth embodiment, the fast tracking RS is allocated in some frequency resources of the bandwidth of the PSCell.

[0127] In the example of (1) in Fig. 13, the fast tracking RS is arranged in one or more resource blocks in the center of the bandwidth of the PSCell, or in one or more subcarriers in the center of the bandwidth of the PSCell. In the example of (2) in Fig. 13, the fast tracking RS is arranged in one or more resource blocks at one end of the bandwidth of the PSCell, or in one or more subcarriers at one end of the bandwidth of the PSCell. In the example of (3) in Fig. 13, the fast tracking RS is arranged in one or more resource blocks at both ends of the bandwidth of the PSCell, or in one or more subcarriers at both ends of the bandwidth of the PSCell.

[0128] Fig. 14 is a diagram showing an example of a system operation according to the fourth embodiment. In Fig. 14, non-essential steps are indicated by dashed lines. Also, duplicated explanations of operations similar to those in the first embodiment will be omitted.

[0129] The operations from step S401 to step S405 are similar to those in the first embodiment described above (FIG. 9).

[0130] In step S406, the MN 200M transmits an RRC Reconfiguration message to the UE 100. The UE 100 receives the RRC Reconfiguration message.

[0131] In the fourth embodiment, the RRC Reconfiguration message may include configuration information related to the fast tracking RS in addition to the information described in the above-mentioned first embodiment. The configuration information related to the fast tracking RS includes at least one of information indicating the presence or absence of a fast tracking RS, information indicating the position of the fast tracking RS on the frequency axis (e.g., a resource block number, a subcarrier number, and / or an ARFCN (Absolute Radio-Frequency Channel Number)), and information assisting demodulation of the fast tracking RS (e.g., a root sequence number indicating a signal sequence of a reference signal, etc.).

[0132] Alternatively, the SN 200S or the MN 200M may broadcast configuration information regarding the fast tracking RS in a system information block (SIB).

[0133] In step S407, the UE 100 transmits an RRC Reconfiguration Complete message to the MN 200M. The MN 200M receives the RRC Reconfiguration Complete message.

[0134] In step S408, the SN 200S transmits a fast tracking RS that is stationary on the time axis in the PSCell that is the target of fast detection. The UE 100 receives the fast tracking RS on the PSCell.

[0135] In step S409, the UE 100 measures the radio quality of the PSCell based on the Fast tracking RS.

[0136] In step S410, the UE 100 determines whether or not the wireless quality condition set in step S406 is satisfied. If it is determined that the wireless quality condition is not satisfied (step S410: NO), the process returns to step S409.

[0137] When it is determined that the radio quality condition is satisfied (step S410: YES), in step S411, the UE 100 starts activating the SCG. Here, the SN 200S transmits a stationary fast tracking RS on the time axis in the PSCell. The UE 100 may use the fast tracking RS to perform control for establishing time / frequency synchronization with the PSCell. In addition, the control unit 130 of the UE 100 may perform CSI measurement, AGC, and beam management for the PSCell using the fast tracking RS.

[0138] The operations from step S412 to step S415 are similar to those in the first embodiment described above (FIG. 9).

[0139] (5) Other embodiments The above-described first to fourth embodiments may be implemented independently, or two or more of the embodiments may be combined and implemented.

[0140] In the above embodiment, an example in which the cells of the SCG are THz-wave cells has been mainly described, but the cells of the SCG are not limited to THz-wave cells. For example, the cells of the SCG may be mmW cells.

[0141] The operational flows in the above-described embodiments do not necessarily have to be performed in chronological order according to the order depicted in the flow diagram. For example, steps in the operations may be performed in an order different from that depicted in the flow diagram, or may be performed in parallel. Also, some of the steps in the operations may be deleted, and additional steps may be added to the process.

[0142] A program may be provided that causes a computer (UE 100, node 200) to execute the operations according to the above-described embodiment. The program may be recorded in a computer-readable medium. Using the computer-readable medium, it is possible to install the program in a computer. Here, the computer-readable medium on which the program is recorded may be a non-transient recording medium. The non-transient recording medium is not particularly limited, and may be, for example, a recording medium such as a CD-ROM or a DVD-ROM.

[0143] As used in this disclosure, the terms "based on" and "depending on / in response to" do not mean "based only on" or "depending only on," unless otherwise specified. The term "based on" means both "based only on" and "based at least in part on." Similarly, the term "depending on" means both "based only on" and "depending at least in part on." Additionally, the terms "include," "comprise," and variations thereof do not mean including only the recited items, but may include only the recited items, or may include additional items in addition to the recited items. Additionally, the term "or" as used in this disclosure is not intended to mean an exclusive or. Additionally, any reference to elements using designations such as "first," "second," etc., as used in this disclosure is not intended to generally limit the quantity or order of those elements. These designations may be used herein as a convenient way to distinguish between two or more elements. Thus, a reference to a first and a second element does not imply that only two elements may be employed therein or that the first element must precede the second element in some manner. In this disclosure, where articles are added by translation, such as, for example, a, an, and the in English, these articles are intended to include the plural unless the context clearly indicates otherwise.

[0144] The above describes the embodiments in detail with reference to the drawings, but the specific configuration is not limited to that described above, and various design changes, etc. are possible without departing from the spirit of the invention.

[0145] (6) Additional Notes The following additional features relate to the above-described embodiment.

[0146] (Appendix 1) A user equipment that performs wireless communication with a master node and a secondary node using dual connectivity in a mobile communication system, A receiving unit that receives information indicating a radio quality condition that should be satisfied in order for the user equipment to perform an activation process for a secondary cell group of the secondary node from the master node; A control unit that measures radio quality for the secondary cell group and evaluates whether the radio quality condition is satisfied, The control unit executes the activation process for the secondary cell group in response to the wireless quality condition being satisfied. User equipment.

[0147] (Appendix 2) The activation process includes a process of transitioning the secondary cell group in an inactive state to an active state. 2. A user device as described in claim 1.

[0148] (Appendix 3) The activation process includes a process of leaving a bandwidth portion in a dormant state in a primary cell of the secondary cell group. 3. A user device according to claim 1 or 2.

[0149] (Appendix 4) a transmission unit configured to transmit a notification regarding the activation process to the master node in response to the wireless quality condition being satisfied. A user device according to any one of Supplementary Notes 1 to 3.

[0150] (Appendix 5) The control unit completes the activation process within a predetermined time from the timing of transmitting the notification or the timing of receiving an acknowledgment to the notification from the master node. 5. A user device as described in claim 4.

[0151] (Appendix 6) The transmission unit transmits information indicating the predetermined time to the master node when transmitting the notification or before transmitting the notification. 6. A user device as described in claim 5.

[0152] (Appendix 7) The receiving unit receives a reference signal continuously transmitted in a time direction from the secondary node on a primary cell of the secondary cell group; The control unit measures the wireless quality based on the reference signal. A user device according to any one of Supplementary Notes 1 to 6.

[0153] (Appendix 8) A node that operates as a master node in a mobile communication system in which a user device performs wireless communication with a master node and a secondary node using dual connectivity, A control unit that sets a secondary cell group of the secondary node to the user equipment; A transmission unit that transmits to the user equipment information indicating a radio quality condition that should be satisfied in order for the user equipment to perform an activation process for the secondary cell group. node.

[0154] (Appendix 9) The activation process includes a process of transitioning the secondary cell group in an inactive state to an active state. Nodes as described in Appendix 8.

[0155] (Appendix 10) The activation process includes a process of leaving a bandwidth portion in a dormant state in a primary cell of the secondary cell group. 10. The node according to claim 8 or 9.

[0156] (Appendix 11) A receiving unit configured to receive a notification regarding the activation process from the user device in response to the wireless quality condition being satisfied in the user device. 11. A node according to any one of appendix 8 to 10.

[0157] (Appendix 12) The control unit determines that the activation process is completed within a predetermined time from the time when the notification is transmitted or from the time when an acknowledgment to the notification is received from the node. 12. The node described in Appendix 11.

[0158] (Appendix 13) The receiving unit receives information indicating the predetermined time from the user device upon receiving the notification or prior to receiving the notification. 13. The node described in Appendix 12.

[0159] (Appendix 14) A communication method for use in a user equipment that performs wireless communication with a node using dual connectivity in a mobile communication system, comprising: receiving information from the node indicating a radio quality condition that should be satisfied in order for the user equipment to perform an activation process for a secondary cell group configured for the user equipment; measuring radio quality for the secondary cell group and evaluating whether the radio quality condition is satisfied; and performing the activation process for the secondary cell group in response to the radio quality condition being satisfied. Communication methods.

[0160] (Appendix 15) A communication method used in a node that performs wireless communication with a user device using dual connectivity in a mobile communication system, comprising: configuring a secondary cell group in the user equipment; transmitting to the user equipment information indicating a radio quality condition that should be satisfied in order for the user equipment to perform an activation process for the secondary cell group; Communication methods. [Explanation of symbols]

[0161] 1: Network 10:RAN 20 :CN 100:UE 110: Receiving unit 120: Transmitter 130: Control section 140: Wireless communication unit 200: Node 210: Transmission unit 220: Receiving unit 230: Control section 240: Network Communications Department 250: Wireless communication section 300:CN device

Claims

1. A user equipment that performs wireless communication with a master node and a secondary node using dual connectivity in a mobile communication system, A receiving unit that receives information indicating a radio quality condition that should be satisfied in order for the user equipment to perform an activation process for a secondary cell group of the secondary node from the master node; A control unit that measures radio quality for the secondary cell group and evaluates whether the radio quality condition is satisfied, The control unit executes the activation process for the secondary cell group in response to the wireless quality condition being satisfied when the secondary cell group has been configured in the user equipment and the secondary cell group is in an inactive state introduced in Release 17 of the 3GPP standard. User equipment.

2. The reception of information indicating the radio quality condition, the measurement of the radio quality, and the evaluation of whether the radio quality condition is satisfied are performed when the user equipment is in an RRC connected state; The activation process includes a process of transitioning the secondary cell group in the inactive state to an active state when the user equipment is in the RRC connected state. The user device of claim 1.

3. The inactive state is a state in which all secondary cells of the secondary cell group are inactive. The user device of claim 1.

4. While the secondary cell group is in the inactive state, the control unit controls the secondary cell group not to transmit a physical uplink shared channel (PUSCH), a sounding reference signal (SRS), and a channel quality indicator (CSI) report. The user device of claim 1.

5. While the secondary cell group is in the inactive state, the control unit controls the secondary cell group not to monitor a physical downlink shared channel (PDCCH) and not to receive a downlink shared channel (DL-SCH). The user device of claim 1.

6. While the secondary cell group is in the inactive state, the control unit controls to continue radio link monitoring (RLM) and measurement reporting for the PSCells of the secondary cell group. The user device of claim 1.

7. When transitioning the secondary cell group to an active state, the control unit skips a random access procedure if a timing advance (TA) with a PSCell of the secondary cell group is valid. The user device of claim 1.

8. a transmission unit configured to transmit a notification regarding the activation process to the master node in response to the wireless quality condition being satisfied. A user equipment according to any preceding claim.

9. A node that operates as a master node in a mobile communication system in which a user equipment performs wireless communication with a master node and a secondary node using dual connectivity, A control unit that sets a secondary cell group of the secondary node to the user equipment; A transmitter that transmits to the user equipment information indicating a radio quality condition that should be satisfied in order for the user equipment to perform an activation process when the secondary cell group has been configured in the user equipment and the secondary cell group is in an inactive state introduced in Release 17 of the 3GPP standard. node.

10. The setting of the secondary cell group and the transmission of the information indicating the radio quality condition are performed when the user equipment is in an RRC connected state, The activation process includes a process of transitioning the secondary cell group in the inactive state to an active state when the user equipment is in the RRC connected state. The node according to claim 9.

11. A receiving unit configured to receive a notification regarding the activation process from the user device in response to the wireless quality condition being satisfied in the user device.

11. A node according to claim 9 or 10.

12. A communication method for use in a user equipment that performs wireless communication with a node using dual connectivity in a mobile communication system, comprising: receiving information from the node indicating a radio quality condition that should be satisfied in order for the user equipment to perform an activation process for a secondary cell group configured for the user equipment; measuring radio quality for the secondary cell group and evaluating whether the radio quality condition is satisfied; and performing the activation process for the secondary cell group in response to the radio quality condition being satisfied when the secondary cell group has been configured in the user equipment and the secondary cell group is in an inactive state introduced in Release 17 of the 3GPP standard. Communication methods.

13. A communication method used in a node that performs wireless communication with a user device using dual connectivity in a mobile communication system, comprising: configuring a secondary cell group in the user equipment; transmitting to the user equipment information indicating a radio quality condition that must be satisfied in order for the user equipment to perform an activation process when the secondary cell group has been configured in the user equipment and the secondary cell group is in an inactive state introduced in Release 17 of the 3GPP standard. Communication methods.

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