User equipment, node, and communication method

Abstract

User equipment according to the present invention uses carrier aggregation to perform wireless communication with a node as part of a mobile communication system and comprises: a reception unit that receives, from the node, information that indicates a wireless quality condition that is to be met for the user equipment to execute deactivation processing for a secondary cell configured for the user equipment; and a control unit that measures wireless quality and evaluates whether the wireless quality condition has been met. The control unit executes the deactivation processing for the secondary cell in response to the wireless quality condition being met.

Description

User equipment, node, and communication method

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

[0002] The Third Generation Partnership Project (3GPP (registered trademark; the same applies hereinafter)), a standardization project for mobile communication systems, defines technical specifications for carrier aggregation (CA). CA can be set for a user equipment (UE) by a node (also simply referred to as a "node") in a network of the mobile communication system.

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

[0004] When CA is configured, the UE has one Radio Resource Control (RRC) connection with the network. Addition and deletion of SCells can be performed by RRC signaling. Activation and deactivation of SCells can be performed by the Medium Access Control (MAC) Control Element (CE).

[0005] Deactivation of an SCell in CA 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 node. Second, the node deactivates the SCell of the UE using a MAC CE based on the measurement report message. Deactivating the SCell transitions the SCell from an active state to a deactivated state, and wireless communication using the SCell is stopped.

[0006] Such deactivation control has the problem that it is difficult to shorten the time between when the radio quality corresponding to the SCell in the UE deteriorates and when radio communication using the SCell is stopped, which may result in wasted power consumption and radio resources.

[0007] 3GPP Technical Specification: TS 38.300 V17.3.0 (2022-12)

[0008] A user equipment according to a first aspect is a user equipment that performs wireless communication with a node using carrier aggregation in a mobile communication system, and includes: a receiving unit that receives, from the node, information indicating a wireless quality condition that must be satisfied in order for the user equipment to perform a deactivation process for a secondary cell configured for the user equipment; and a control unit that measures wireless quality and evaluates whether the wireless quality condition is satisfied. The control unit executes the deactivation process for the secondary cell in response to the wireless quality condition being satisfied.

[0009] A node according to a second aspect is a node that performs wireless communication with a user equipment using carrier aggregation in a mobile communication system, and includes a control unit that sets a secondary cell for the user equipment, and a transmission unit that transmits to the user equipment information indicating a wireless quality condition that must be satisfied for the user equipment to perform a deactivation process for the secondary cell.

[0010] A communication method according to a third aspect is a communication method used by a user equipment that performs wireless communication with a node using carrier aggregation in a mobile communication system, and includes the steps of receiving, from the node, information indicating a wireless quality condition that must be satisfied in order for the user equipment to perform a deactivation process for a secondary cell configured for the user equipment; measuring the wireless quality and evaluating whether the wireless quality condition is satisfied; and performing the deactivation process for the secondary cell in response to the wireless quality condition being satisfied.

[0011] A communication method according to a fourth aspect is a communication method used in a node that performs wireless communication with a user equipment using carrier aggregation in a mobile communication system, and includes the steps of setting a secondary cell in the user equipment, and transmitting information to the user equipment indicating a wireless quality condition that must be satisfied for the user equipment to perform a deactivation process for the secondary cell.

[0012] 1 is a diagram illustrating an example of the configuration of a mobile communication system according to an embodiment. FIG. 2 is a diagram illustrating an example of the configuration of a protocol stack of a radio interface of a U-plane that handles data. FIG. 3 is a diagram illustrating an example of the configuration of a protocol stack of a radio interface of a C-plane that handles signaling (control signals). FIG. 4 is a diagram for explaining a terahertz (THz) wave cell according to an embodiment. FIG. 5 is a diagram for explaining carrier aggregation (CA) according to an embodiment. FIG. 6 is a diagram illustrating a general procedure for adding and activating a secondary cell (SCell). FIG. 7 is a diagram illustrating a general procedure for deactivating an SCell. FIG. 8 is a diagram illustrating an example of the configuration of a UE (user equipment) according to an embodiment. FIG. 9 is a diagram illustrating an example of the configuration of a node according to an embodiment. FIG. 10 is a diagram illustrating an example of the system operation according to the first embodiment. FIG. 11 is a diagram illustrating a bandwidth portion (BWP). FIG. 12 is a diagram illustrating an example of the system operation according to a second embodiment. FIG. 13 is a diagram illustrating a specific example of a reference signal (Fast tracking RS) according to a third embodiment. FIG. 14 is a diagram illustrating an example of the system operation according to the third embodiment.

[0013] 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.

[0014] (1) First Embodiment A first embodiment will be described with reference to FIGS. 1 to 10. FIG.

[0015] (1.1) System Configuration Example Fig. 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.

[0016] 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 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).

[0017] 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), 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).

[0018] 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 may be configured (i.e., functionally divided) with a CU (Central Unit) and a DU (Distributed Unit), and the two 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.

[0019] 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").

[0020] The CN 20 includes a CN device 300. The CN device 300 may include a C-plane device corresponding to the control plane (C-plane) and a U-plane device corresponding to the 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 controls data transfer. When the mobile communication system is 5GS, the C-plane device is referred to as an AMF (Access and Mobility Management Function), the U-plane device is referred to as a UPF (User Plane Function), and the interface between the node 200 and the CN device 300 is referred to as an NG interface.

[0021] FIG. 2 is a diagram showing an example of the configuration of a protocol stack of a U-plane radio interface that handles data.

[0022] 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.

[0023] The PHY layer performs encoding / decoding, modulation / demodulation, antenna mapping / demapping, and resource mapping / demapping. Data and control information are transmitted between the PHY layer of UE 100 and the PHY layer of node 200 via a physical channel. The PHY layer of UE 100 receives downlink control information (DCI) transmitted from node 200 on a physical downlink control channel (PDCCH). Specifically, UE 100 performs blind decoding of the PDCCH using a radio network temporary identifier (RNTI) and acquires successfully decoded DCI as DCI addressed to the UE. The DCI transmitted from node 200 has CRC parity bits scrambled by the RNTI added.

[0024] The MAC layer performs data priority control and retransmission processing using Hybrid ARQ (HARQ). Data and control information are transmitted between the MAC layer of UE 100 and the MAC layer of node 200 via a transport channel. The MAC layer of 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 UE 100.

[0025] 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.

[0026] The PDCP layer performs header compression / decompression, encryption / decryption, and the like.

[0027] The SDAP layer maps IP flows, which are units for QoS control by the CN 20, to radio bearers, which are units for QoS control by the AS (Access Stratum). Note that if the RAN is connected to the EPC, SDAP may not be required.

[0028] FIG. 3 is a diagram showing an example of the configuration of a protocol stack of a C-plane radio interface that handles signaling (control signals).

[0029] The protocol stack of the C-plane radio interface includes, for example, an RRC (Radio Resource Control) layer and an NAS (Non-Access Stratum) layer instead of the SDAP layer shown in FIG.

[0030] RRC signaling for various settings is transmitted between the RRC layer of UE100 and the RRC layer of node 200. The RRC layer controls logical channels, transport channels, and physical channels in accordance with the establishment, re-establishment, and release of radio bearers. When there is a connection (RRC connection) between the RRC of UE100 and the RRC of node 200, UE100 is in an RRC connected state. When there is no connection (RRC connection) between the RRC of UE100 and the RRC of node 200, UE100 is in an RRC idle state. When the connection between the RRC of UE100 and the RRC of node 200 is suspended, UE100 is in an RRC inactive state.

[0031] 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 the UE 100 and the NAS layer of the CN device 300. Note that the UE 100 also has an application layer in addition to the radio interface protocol. The layer below the NAS layer is referred to as the AS layer (also simply referred to as "AS").

[0032] (1.2) CA Using Terahertz Wave Cell FIG. 4 is a diagram for explaining a terahertz (THz) wave cell according to an embodiment.

[0033] The mobile communication system according to the embodiment may be a 6G system. It is expected that 6G will utilize terahertz (THz) waves. A cell operated using THz waves is called a THz wave cell. Compared to millimeter waves (mmW), THz waves have a stronger tendency to propagate in a straighter direction, 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.

[0034] 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 these assumptions, for example, UE 100 moving at 60 [km / s] passes through the coverage area of ​​each THz wave cell in about 599 [ms].

[0035] Carrier aggregation (CA) is one method for stably controlling small cells in a mobile communication system. In the embodiment, it is assumed that a THz wave cell is used as a secondary cell (SCell) of CA. Note that it is assumed that a primary cell (PCell) of CA is a macrocell, but the PCell may also be an mmW cell.

[0036] FIG. 5 is a diagram for explaining carrier aggregation (CA) according to the embodiment.

[0037] The UE 100 in the RRC connected state may be configured with CA by the node 200. In CA, multiple component carriers (CCs) corresponding to multiple serving cells are aggregated, and the UE can simultaneously receive or transmit on multiple CCs (multiple cells). The multiple CCs may be contiguous or non-contiguous in the frequency direction. One serving cell is called a primary cell (PCell), and a set of serving cells is formed by configuring the UE with one or more secondary cells (SCells) together with the PCell. When CA is configured, the UE 100 has one RRC connection with the network 1. Addition and deletion of the SCell can be performed by RRC signaling. Activation and deactivation of the SCell can be performed by a medium access control (MAC) control element (CE).

[0038] The mobile communication system supports cell activation and deactivation to enable reduction of power consumption of the UE 100 when CA is configured. When an SCell is in an inactive state, the UE 100 does not need to receive a PDCCH or a physical downlink shared channel (PDSCH) in the SCell, and uplink transmission is not possible in the SCell. The UE 100 does not need to perform channel quality indicator (CQI) measurement for the SCell in an inactive state. On the other hand, when the SCell is in an active state, the UE 100 receives a PDSCH and a PDCCH in the SCell. The UE 100 can perform CQI measurement for the SCell in an active state.

[0039] Note that when node 200 reconfigures the set of serving cells, it first activates or deactivates the SCells that have been added to the set, and the SCells that remain in the set (either unchanged or reconfigured) do not change their activation state (activated or deactivated).

[0040] FIG. 6 illustrates the general procedure for adding and activating an SCell.

[0041] In step S11, the UE 100 transmits a measurement report message including measurement results of the radio quality of each cell to the node 200, for example, on the PCell. The radio quality may be any index related to radio quality, and 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 in response to an event trigger. The node 200 receives the Measurement Report message.

[0042] In step S12, the node 200 determines to configure (add) an SCell to the UE 100 based on the Measurement Report message, and transmits an RRC reconfiguration message for adding the SCell to the UE 100 to the UE 100, for example, on the PCell. The RRC reconfiguration message is transmitted and received in the RRC layer. The UE 100 receives the RRC reconfiguration message.

[0043] In step S13, the UE 100 transmits an RRC Reconfiguration Complete message indicating that the addition of the SCell based on the RRC Reconfiguration message has been completed to the node 200, for example, on the PCell. The RRC Reconfiguration Complete message is transmitted and received in the RRC layer. The node 200 receives the RRC Reconfiguration Complete message. At this stage, the added SCell is in an inactive state.

[0044] In step S14, the node 200 transmits a MAC CE for activating the SCell added to the UE 100 to the UE 100, for example, on the PCell. The MAC CE is transmitted and received in the MAC layer. When the UE 100 receives the MAC CE, it starts activating the SCell. When the UE 100 starts activating the SCell, the UE 100 receives a reference signal of the SCell, and performs channel state information (CSI) measurement, automatic gain control (AGC), and beam management to prepare for communication.

[0045] In step S15, the UE 100 transmits a HARQ ACK indicating successful reception of the MAC CE to the node 200, for example, on the PUCCH of the PCell. The node 200 receives the HARQ ACK.

[0046] In step S16, when the SCell becomes active in the UE 100, the UE 100 and the node 200 start wireless communication using the SCell.

[0047] According to this procedure, it takes, for example, about 35 ms after the radio quality of the SCell becomes communicable until the UE 100 can use the SCell. If the SCell is a THz wave cell, the coverage area of ​​the SCell becomes even narrower due to influences such as obstruction, so the time during which the SCell can be used is short. Therefore, the procedure of Fig. 6 requires a long time to complete activation of the SCell, which results in a problem of shortening the time during which data can actually be transmitted and received on the SCell.

[0048] Here, as a technology that can speed up SCell activation, the following extended functions have been introduced in the 3GPP standard up to Release 17.

[0049] A first extension function is direct SCell activation. In direct SCell activation, the node 200 can specify the active state as the initial state of the SCell when adding the SCell to the UE 100 using an RRC message. This eliminates the need to send and receive the MAC CE for SCell activation in Fig. 6, thereby speeding up SCell activation.

[0050] A second extension function is a technique called dormant BWP. The node 200 can configure a dormant bandwidth portion (BWP) for the SCell. If the active BWP of the activated SCell is a dormant BWP, the UE 100 stops PDCCH monitoring and sounding reference signal (SRS) / PUSCH / PUCCH transmission in the SCell, but continues to perform CSI measurement, AGC, and beam management. PDCCH / downlink control information (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 network 1 via dedicated RRC signaling. An example of using the dormant BWP will be described in a second embodiment.

[0051] The third extension is to configure aperiodic CSI-RS for SCells for tracking (synchronization) for fast SCell activation. Such aperiodic CSI-RS can support AGC and time / frequency synchronization. MAC CE is used to trigger SCell activation and aperiodic CSI-RS for deactivated SCells.

[0052] FIG. 7 illustrates a general procedure for SCell deactivation.

[0053] In step S21, the SCell is in an active state in the UE 100, and the UE 100 and the node 200 are performing wireless communication using the SCell.

[0054] Here, it is assumed that the radio quality of the SCell in the UE 100 deteriorates, and it becomes difficult to continue radio communication using the SCell.

[0055] In step S22, the UE 100 transmits a measurement report message including the measurement result of the radio quality of each cell, for example, on the PCell, to the node 200. The node 200 receives the Measurement Report message.

[0056] In step S23, the node 200 recognizes deterioration of the radio quality of the SCell in the UE 100 based on the Measurement Report message, and transmits a MAC CE (SCell deactivation MAC CE) for deactivating the SCell of the UE 100 to the UE 100, for example, on the PCell. The UE 100 receives the MAC CE.

[0057] In step S24, the UE 100 transmits a HARQ ACK indicating successful reception of the MAC CE to the node 200, for example, on the PUCCH of the PCell. The node 200 receives the HARQ ACK.

[0058] In step S25, UE 100 deactivates SCell in response to receiving the MAC CE in step S23. For example, UE 100 stops PDCCH monitoring and CQI measurement for SCell. Meanwhile, node 200 stops DL transmission processing (PDCCH transmission, PDSCH transmission) on SCell of UE 100 in response to receiving the HARQ ACK in step S24. As a result, wireless communication using SCell is stopped.

[0059] In the operation shown in Fig. 7, when the SCell radio quality in UE 100 deteriorates, communication on the SCell becomes impossible. However, node 200 cannot grasp the deterioration of the SCell radio quality until it receives the Measurement Report message in step S22, and may continue the DL transmission process even after the SCell radio quality deteriorates. Furthermore, UE 100 may continue PDCCH monitoring (and CQI measurement) on the SCell until it receives the MAC CE in step S23. Such an operation has the problem of wasting resources and power consumption.

[0060] For example, the delay from when the SCell radio quality in UE 100 deteriorates to when the Measurement Report message is transmitted may be approximately 10 ms, and the delay from when node 200 receives the Measurement Report message to when it transmits the SCell deactivation MAC CE to UE 100 may be approximately 10 ms. In this case, resources and power consumption may be wasted for approximately 20 ms. Therefore, it is desirable to be able to deactivate the SCell quickly when the SCell radio quality no longer satisfies the predetermined quality.

[0061] (1.3) Example of Configuration of User Equipment FIG. 8 is a diagram illustrating an example of the configuration of the UE 100 (user equipment) according to the embodiment.

[0062] 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.

[0063] 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 it 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 it from the antenna.

[0064] The control unit 130 performs various controls and processes in the UE 100. The operations of the UE 100 described above and below may be operations controlled by 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.

[0065] The UE 100 configured in this manner performs wireless communication with the node 200 using CA. The receiver 110 receives, from the node 200, information indicating a wireless quality condition that must be satisfied in order for the UE 100 to perform a deactivation process for the SCell configured in the UE 100. The controller 130 measures the wireless quality of the SCell and evaluates whether the wireless quality condition is satisfied. The controller 130 performs a deactivation process for the SCell in response to the wireless quality condition being satisfied.

[0066] As a result, the UE 100 can autonomously perform the deactivation process for the SCell when the radio quality for the SCell satisfies the radio quality condition (for example, when the radio quality deteriorates below a predetermined quality). On the other hand, in the conventional technology, the node 200 needs to recognize that the radio quality for the SCell satisfies the radio quality condition based on the Measurement Report message and instruct the UE 100 to deactivate the SCell.

[0067] In the embodiment, the radio quality condition is set in the UE 100, and whether or not the radio quality condition is satisfied can be determined on the UE 100 side. Therefore, the UE 100 can autonomously perform the deactivation process for the SCell without transmitting a Measurement Report message to the node 200. Therefore, it is possible to speed up the deactivation of the SCell.

[0068] In the first embodiment, the deactivation process includes a process of transitioning an SCell in an active state to a deactivated state. The activation process may include a process of transitioning a BWP in a non-dormant state in the SCell to a dormant state. An example using a dormant BWP will be described in a second embodiment.

[0069] In the embodiment, the transmitting unit 120 transmits a notification regarding the deactivation process to the node 200 in response to the wireless quality condition being satisfied. This allows the node 200 to understand that the UE 100 will perform the deactivation process based on the notification. Therefore, wireless communication using the SCell can be smoothly stopped. The notification may be a newly introduced MAC CE. Because the MAC CE is transmitted and received at the MAC layer, it can be transmitted faster than a Measurement Report message.

[0070] In the embodiment, the transmitter 120 transmits a notification regarding the deactivation process to the node 200 on the PCell. This allows the notification to be transmitted to the node 200 even if the wireless quality of the SCell deteriorates. This allows wireless communication using the SCell to be stopped smoothly and quickly.

[0071] In the embodiment, the control unit 130 stops monitoring the PDCCH (and measuring the CQI) for the SCell when the radio quality condition is satisfied or when an acknowledgment (HARQ ACK) to the notification regarding the deactivation process is received from the node 200. This can prevent the above-mentioned waste of resources and power consumption from occurring.

[0072] (1.4) Example of Node Configuration FIG. 9 is a diagram illustrating an example of the configuration of a node 200 (base station) according to the embodiment.

[0073] 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.

[0074] 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.

[0075] 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.

[0076] The NW communication unit 240 is connected to adjacent nodes via an inter-node interface, and to the CN device 300 via a node-CN interface.

[0077] The node 200 configured in this manner performs wireless communication with the UE 100 using CA. The control unit 230 sets an SCell in the UE 100. The transmission unit 210 transmits, to the UE 100, information indicating a radio quality condition that must be satisfied in order for the UE 100 to perform a deactivation process for the SCell. As a result, the UE 100 can autonomously perform a deactivation process for the SCell when the radio quality for the SCell satisfies the radio quality condition.

[0078] In the embodiment, the receiving unit 220 receives a notification regarding the deactivation process from the UE 100 in response to the radio quality condition being satisfied in the UE 100. For example, the receiving unit 220 receives the notification from the UE 100 on the PCell.

[0079] In the embodiment, the control unit 230 stops the DL transmission process (PDCCH transmission, PDSCH transmission) on the SCell when it receives a notification regarding the deactivation process or when it transmits an acknowledgment (HARQ ACK) in response to the notification to the UE 100. This allows the DL transmission process to be stopped earlier than in the general procedure shown in Fig. 7, thereby making it possible to suppress the waste of resources and power consumption as described above.

[0080] (1.5) System Operation Example Fig. 10 is a diagram showing an example of system operation according to the first embodiment. In Fig. 10, non-essential steps are indicated by dashed lines. Furthermore, duplicated explanations of operations similar to those in Figs. 6 and 7 will be omitted.

[0081] In step S101, the receiving unit 110 of the UE 100 receives a reference signal from each cell, the control unit 130 of the UE 100 measures radio quality based on the reference signal, and the transmitting unit 120 of the UE 100 transmits a Measurement Report message including the measurement results to the node 200, for example, on the PCell. Here, the Measurement Report message includes the measurement results of the THz wave cell. The receiving unit 220 of the node 200 receives the Measurement Report message.

[0082] In step S102, the control unit 230 of the node 200 generates an RRC Reconfiguration message, and the transmission unit 210 of the node 200 transmits the RRC Reconfiguration message, for example, on the PCell, to the UE 100. The reception unit 110 of the UE 100 receives the RRC Reconfiguration message.

[0083] The RRC Reconfiguration message includes, for example, configuration information for adding an SCell, configuration information for configuring the activation of the SCell (i.e., information specifying the active state as the initial state of the SCell), and configuration information for conditional SCell deactivation. In the illustrated example, the configuration information for adding an SCell, the configuration information for configuring the activation of the SCell, and the configuration information for conditional SCell deactivation are transmitted in one RRC Reconfiguration message, but these pieces of information may be transmitted in separate RRC Reconfiguration messages.

[0084] The configuration information for adding an SCell may be sCellToAddModList, which is a list of SCells to be added or modified. sCellToAddModList is a list having SCell configurations (SCellConfig) as entries. Each SCell configuration (SCellConfig) includes the index (sCellIndex) of the corresponding SCell and the configurations (sCellConfigCommon and sCellConfigDedicated) of the corresponding SCell.

[0085] Configuration information for conditional SCell deactivation may be included in the SCell configuration (SCellConfig). The configuration information for conditional SCell deactivation may include information for configuring the frequency and / or cell ID of the target SCell.

[0086] The configuration information for conditional SCell deactivation includes information indicating radio quality conditions that must be satisfied for the UE 100 to deactivate the corresponding SCell.

[0087] Here, the information indicating the radio quality condition may include, for example, at least one radio quality threshold among an RSRP threshold, an RSRQ threshold, and an SINR threshold. Satisfying the radio quality condition for the SCell may mean at least one of the following: the RSRP of the SCell is below the RSRP threshold, the RSRQ of the SCell is below the RSRQ threshold, and the SINR of the SCell is below the SINR threshold.

[0088] The information indicating the radio quality condition may include a threshold value of the duration of a state in which a radio problem is detected in a lower layer (for example, a PHY layer) in the UE 100. In this case, satisfying the radio quality condition for the SCell may mean that the duration of the state in which a radio problem is detected for the SCell reaches the threshold value.

[0089] The information indicating the radio quality condition may include a threshold value of the number of times retransmission continues (i.e., the number of times UL data transmission failures continue) in the UE 100. In this case, satisfying the radio quality condition for the SCell may mean that the number of times retransmission continues for the SCell (i.e., the number of times UL data transmission failures continue for the SCell) has reached the threshold value.

[0090] The information indicating the radio quality condition may include a threshold value of a time during which UL data transmission cannot be performed based on the detection of an interference wave in UE 100. For example, when SCell is operated in an unlicensed band, UE 100 performs carrier sense for SCell, and performs UL data transmission only when there is an available channel, and does not perform UL data transmission when there is no available channel. In this case, satisfying the radio quality condition for SCell may mean that the time during which UL data transmission using carrier sense cannot be performed reaches a threshold value.

[0091] In step S103, the control unit 130 of the UE 100 generates an RRC Reconfiguration Complete message, and the transmission unit 210 of the UE 100 transmits the RRC Reconfiguration Complete message, for example, on the PCell, to the node 200. The reception unit 220 of the node 200 receives the RRC Reconfiguration Complete message.

[0092] The initial state of the SCell added to the UE 100 may be an active state (step S104). Alternatively, after the SCell is added to the UE 100, the SCell may be activated by a MAC CE (step S104). Note that the control unit 130 of the UE 100 starts radio quality measurement (e.g., RSRP measurement, RSRQ measurement, and / or SINR measurement) for the SCell based on the configuration information for conditional SCell deactivation.

[0093] In step S105, the receiving unit 110 of the UE 100 receives a reference signal of the SCell, and the control unit 130 of the UE 100 measures radio quality based on the reference signal. The reference signal of the SCell may be a demodulation reference signal (DMRS) included in an SSB (SS / PBCH Block) transmitted by the SCell, or a tracking reference signal (TRS), which is a type of CSI-RS. The measurement of radio quality may include at least one of measuring the duration of a state in which a radio problem is detected, measuring the number of retransmissions that continue (i.e., the number of times UL data transmission failures continue), and measuring the time during which UL data transmission cannot be performed.

[0094] In step S106, the control unit 130 of the UE 100 determines whether the radio quality condition set in step S102 is satisfied. For example, the control unit 130 of the UE 100 compares the measurement result (e.g., RSRP, RSRQ, and / or SINR) of step S105 with the radio quality threshold set in step S102, and determines that the radio quality condition is satisfied if the measurement result is below the radio quality threshold. If it is determined that the radio quality condition is not satisfied (step S106: NO), the process returns to step S105.

[0095] On the other hand, if it is determined that the radio quality condition is satisfied (step S106: YES), in step S107, the control unit 130 of the UE 100 deactivates the SCell. For example, the control unit 130 of the UE 100 stops processing such as PDCCH monitoring for the SCell. Note that the SCell deactivation may be performed when receiving the positive response (HARQ ACK) in step S109.

[0096] In step S108, the control unit 130 of the UE 100 triggers the transmission of an SCell deactivation notification, and the transmission unit 120 of the UE 100 transmits the SCell deactivation notification on the PCell to the node 200. The reception unit 220 of the node 200 receives the SCell deactivation notification.

[0097] The SCell deactivation notification may be a newly introduced MAC CE. For example, the SCell deactivation notification may include an index value (which may be a cell ID) of the deactivated SCell. However, the SCell deactivation notification may be a notification included in UCI transmitted on the PUCCH, a PDCP Control PDU, or an RRC message.

[0098] The SCell deactivation notification may include an index of the activated SCell. The index may refer to each entry in the SCell configuration list configured by RRC Reconfiguration. Instead of the index, the cell ID of the activated SCell may be notified. Alternatively, in a bitmap notification, each bit position may be associated with each SCell, and each bit (0 / 1) may indicate whether or not the SCell is activated.

[0099] The SCell deactivation notification may include information on the timing when the SCell deactivation (i.e., step S107) was performed. The timing information may be the radio frame number when the SCell deactivation was performed, or may be expressed by any one or a combination of a system frame number, a subframe number, a slot number, and a symbol number. The timing information may also be time information when the SCell deactivation was performed. The timing information may be the elapsed time from the execution of the SCell deactivation to the transmission of the SCell deactivation notification, and may be expressed in seconds (e.g., milliseconds) or the number of radio frames (e.g., the number of slots). Such timing information allows the node 200 to know when DL reception in the SCell stopped, and to efficiently identify data packets to be retransmitted when retransmitting data transmitted in DL during that period to the PCell.

[0100] Prior to transmission of the SCell deactivation notification, the following processing may be performed in the PHY layer and the MAC layer. Specifically, UE 100 transmits a Scheduling Request (SR) to node 200, node 200 transmits a UL grant for a Buffer Status Report (BSR) to UE 100, UE 100 transmits the BSR to node 200, and node 200 transmits a UL grant for PUSCH transmission to UE 100. Then, UE 100 transmits the SCell deactivation notification based on the UL grant for PUSCH transmission.

[0101] Although an example has been described in which UE 100 transmits an SCell deactivation notification to node 200 on PCell, if the SCell is to be deactivated upon receiving a positive response (HARQ ACK), the SCell deactivation notification may be transmitted to node 200 on SCell.

[0102] In step S109, the transmitter 210 of the node 200 transmits a HARQ ACK indicating successful reception of the SCell deactivation notification to the UE 100 on the PDCCH of the PCell. The receiver 110 of the UE 100 receives the HARQ ACK. Note that if the SCell deactivation notification is a UCI, step S109 does not need to be performed.

[0103] In response to receiving the SCell deactivation notification in step S108, node 200 recognizes that the SCell of UE 100 has become unavailable. In step S110, node 200 stops DL transmission to UE 100 via the SCell.

[0104] (2) Second Embodiment With reference to FIGS. 11 and 12, the second embodiment will be described, focusing mainly on the differences from the first embodiment.

[0105] (2.1) BWP FIG. 11 is a diagram for explaining BWP.

[0106] 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 portion of the cell bandwidth (which may also be called the "system bandwidth" or "carrier bandwidth") is called a BWP. In BA, the node 200 configures one or more BWPs for the UE 100 within the cell and notifies the UE 100 which of the configured BWPs is currently active. BWPs include 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 are variably configurable.

[0107] In the illustrated example, three different BWPs are set in the UE 100, and an example is shown in which the active BWP is switched between these BWPs. １ has a width of 40 [MHz] and a subcarrier spacing of 15 [kHz], and BWP ２ has a width of 10 MHz and a subcarrier spacing of 15 kHz, and BWP ３ has a width of 20 MHz and a subcarrier spacing of 60 kHz.

[0108] In each of the UL and DL, there is only one BWP in the active state, and the rest are in the 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 (PUSCH).

[0109] In the case of CA, the node 200 can configure a dormant BWP for the SCell. If the active BWP of the activated SCell is a dormant BWP, the UE 100 stops PDCCH monitoring and SRS / PUSCH / PUCCH transmission in 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.

[0110] (2.2) System Operation Example As in the first embodiment, the UE 100 according to the second embodiment performs wireless communication with the node 200 using CA. The receiver 110 receives, from the node 200, information indicating a wireless quality condition that must be satisfied in order for the UE 100 to perform a deactivation process for an SCell configured in the UE 100. The controller 130 measures the wireless quality of the SCell and evaluates whether the wireless quality condition is satisfied. The controller 130 performs a deactivation process for the SCell in response to the wireless quality condition being satisfied. In the second embodiment, the deactivation process includes a dormant transition process for transitioning a BWP in a non-dormant state in the SCell to a dormant state.

[0111] According to the second embodiment, the control unit 130 of the UE 100 transitions the BWP in the non-dormant state to the dormant state for the SCell in the active state in response to satisfaction of the radio quality condition set by the node 200. This allows the BWP in the non-dormant state to autonomously transition to the dormant state without transmitting a Measurement Report message to the node 200 or receiving a DCI indicating transition to the dormant BWP.

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

[0113] In step S201, the receiving unit 110 of the UE 100 receives a reference signal from each cell, the control unit 130 of the UE 100 measures the radio quality based on the reference signal, and the transmitting unit 120 of the UE 100 transmits a Measurement Report message including the measurement result to the node 200, for example, on the PCell. Here, the Measurement Report message includes the measurement result of the THz wave cell. The receiving unit 220 of the node 200 receives the Measurement Report message.

[0114] In step S202, the control unit 230 of the node 200 generates an RRC Reconfiguration message, and the transmission unit 210 of the node 200 transmits the RRC Reconfiguration message, for example, on the PCell, to the UE 100. The reception unit 110 of the UE 100 receives the RRC Reconfiguration message.

[0115] The RRC Reconfiguration message includes, for example, configuration information for adding an SCell, configuration information for specifying an active state as the initial state of the SCell, configuration information for configuring a BWP (dedicated BWP) for the SCell, and configuration information for transitioning to a conditional dormant BWP. In the illustrated example, the configuration information for adding an SCell, the configuration information for specifying an active state as the initial state of the SCell, the configuration information for configuring a BWP (dedicated BWP) for the SCell, and the configuration information for transitioning to a conditional dormant BWP are transmitted in one RRC Reconfiguration message, but these pieces of information may be transmitted in separate RRC Reconfiguration messages.

[0116] The configuration information for adding an SCell may be sCellToAddModList, which is a list of SCells to be added or changed. sCellToAddModList is a list having SCell configurations (SCellConfig) as entries. Each SCell configuration (SCellConfig) includes the index (sCellIndex) of the corresponding SCell and the configuration of the corresponding SCell (sCellConfigCommon and sCellConfigDedicated). The SCell configuration (SCellConfig) may include configuration information for specifying the active state as the initial state of the SCell, configuration information for configuring BWP (dedicated BWP) for the SCell, and configuration information for transitioning to conditional dormant BWP.

[0117] The configuration information for transitioning to a conditional dormant BWP includes information indicating a radio quality condition that must be satisfied in order to transition an active BWP of a corresponding active SCell to a dormant state when the active BWP is a non-dormant BWP. 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. The information indicating the radio quality condition may include at least one of a threshold for the duration of a state in which a radio problem is detected, a threshold for the number of retransmissions that continue in the UE 100 (i.e., the number of times UL data transmission failures continue), and a threshold for the time during which UL data transmission cannot be performed based on the detection of an interference wave.

[0118] In the second embodiment, the initial state of the active BWP of the SCell added to the UE 100 is the non-dormant state. The control unit 130 of the UE 100 starts radio quality measurement for the SCell based on the configuration information for transition to the conditional dormant BWP.

[0119] In step S203, the control unit 130 of the UE 100 generates an RRC Reconfiguration Complete message, and the transmission unit 210 of the UE 100 transmits the RRC Reconfiguration Complete message, for example, on the PCell, to the node 200. The reception unit 220 of the node 200 receives the RRC Reconfiguration Complete message.

[0120] The initial state of the SCell added to the UE 100 may be an active state (step S204). Alternatively, after the SCell is added to the UE 100, the SCell may be activated by a MAC CE (step S204).

[0121] In step S205, the receiver 110 of the UE 100 receives a reference signal of the SCell, and the controller 130 of the UE 100 measures radio quality based on the reference signal. The reference signal of the SCell may be a DMRS or a TRS included in an SSB transmitted by the SCell. The measurement of radio quality may include at least one of measuring the duration of a state in which a radio problem is detected, measuring the number of retransmissions that continue, and measuring the time during which UL data transmission cannot be performed.

[0122] In step S206, the control unit 130 of the UE 100 determines whether the radio quality condition set in step S202 is satisfied. For example, the control unit 130 of the UE 100 compares the measurement result (e.g., RSRP, RSRQ, and / or SINR) of step S205 with the radio quality threshold set in step S202, and determines that the radio quality condition is satisfied if the measurement result is below the radio quality threshold. If it is determined that the radio quality condition is not satisfied (step S206: NO), the process returns to step S205.

[0123] On the other hand, when it is determined that the radio quality condition is satisfied (step S206: YES), in step S207, the control unit 130 of the UE 100 transitions the SCell to a dormant state (i.e., switches from a non-dormant state to a dormant state).

[0124] In step S208, the control unit 130 of the UE 100 triggers the transmission of an SCell BWP sleep transition notification, and the transmission unit 120 of the UE 100 transmits the SCell BWP sleep transition notification on the PCell to the node 200. The reception unit 220 of the node 200 receives the SCell BWP sleep transition notification.

[0125] The SCell BWP sleep transition notification may include information on the timing when the SCell BWP sleep transition (i.e., step S207) was performed. The timing information may be the radio frame number when the SCell BWP sleep transition was performed, or may be expressed by any one or a combination of a system frame number, a subframe number, a slot number, and a symbol number. The timing information may be time information when the SCell BWP sleep transition was performed. The timing information may be the elapsed time from the performance of the SCell BWP sleep transition to the transmission of the SCell BWP sleep transition notification, and may be expressed in seconds (e.g., milliseconds) or the number of radio frames (e.g., the number of slots). Such timing information allows the node 200 to know when DL reception in the SCell stopped, and to efficiently identify data packets to be retransmitted when retransmitting data transmitted in DL during that period to the PCell.

[0126] The SCell BWP sleep transition notification may be a newly introduced MAC CE. The SCell BWP sleep transition notification includes an index value (which may be a cell ID) of the SCell that has transitioned to sleep BWP and / or a BWP ID of the BWP. However, the SCell BWP sleep transition notification may be a notification included in UCI transmitted on the PUCCH, a PDCP Control PDU, or an RRC message.

[0127] Prior to transmission of the SCell BWP dormant transition notification, the following processing may be performed in the PHY layer and the MAC layer. Specifically, UE 100 transmits an SR to node 200, node 200 transmits an UL grant for BSR to UE 100, UE 100 transmits a BSR to node 200, and node 200 transmits an UL grant for PUSCH transmission to UE 100. Then, UE 100 transmits the SCell BWP dormant transition notification based on the UL grant for PUSCH transmission.

[0128] Note that, although an example in which the UE 100 transmits the SCell BWP dormant transition notification to the node 200 on the PCell has been described, the SCell BWP dormant transition notification may be transmitted to the node 200 on the SCell.

[0129] In step S209, the transmitter 210 of the node 200 transmits a HARQ ACK indicating successful reception of the SCell BWP sleep transition notification to the UE 100 on the PDCCH of the PCell. The receiver 110 of the UE 100 receives the HARQ ACK. Note that if the SCell BWP sleep transition notification is UCI, step S209 does not need to be performed.

[0130] In response to receiving the SCell BWP dormant transition notification in step S208, the node 200 recognizes that the active BWP of the SCell of the UE 100 has become unavailable. In step S210, the node 200 stops DL transmission on the active BWP of the SCell.

[0131] (3) Third Embodiment A third embodiment will be described with reference to Figures 13 and 14, focusing on differences from the above-described embodiments. The third embodiment is based on the first embodiment. However, the third embodiment may also be based on the second embodiment.

[0132] In the above-described embodiment, the UE 100 detects that the radio quality of the SCell satisfies a predetermined quality and performs SCell deactivation or transition to dormant BWP. Here, in order to quickly detect that the radio quality of the SCell satisfies a predetermined quality, it is desirable that the UE 100 can constantly measure the radio quality of the SCell. In the above-described embodiment, an example has been described in which the UE 100 measures radio quality (RSRP, etc.) using an SSB or TRS (CSI-RS) as a reference signal, but these reference signals are transmitted discretely in time. Therefore, at times when the SSB or CSI-RS is not transmitted, the UE 100 cannot perform radio communication measurements, and a delay may occur when detecting that the radio quality of the SCell satisfies a predetermined quality.

[0133] Therefore, in the third embodiment, the transmitter 210 of the node 200 continuously transmits a reference signal (also referred to as a "Fast Tracking RS") used for measuring radio quality on the SCell in the time direction. The receiver 110 of the UE 100 receives the Fast Tracking RS transmitted continuously in the time direction on the SCell from the node 200. The control unit 130 of the UE 100 measures the radio quality of the SCell based on the Fast Tracking RS. This makes it possible to suppress the above-mentioned delay.

[0134] 13 is a diagram showing a specific example of a fast tracking RS according to the third embodiment. The fast tracking RS according to the third embodiment is arranged in some frequency resources of the bandwidth of a cell (SCell).

[0135] In the example of (1) in Figure 13, the fast tracking RS is arranged in one or more resource blocks at the center of the bandwidth of the SCell, or in one or more subcarriers at the center of the bandwidth of the SCell. In the example of (2) in Figure 13, the fast tracking RS is arranged in one or more resource blocks at one end of the bandwidth of the SCell, or in one or more subcarriers at one end of the bandwidth of the SCell. In the example of (3) in Figure 13, the fast tracking RS is arranged in one or more resource blocks at both ends of the bandwidth of the SCell, or in one or more subcarriers at both ends of the bandwidth of the SCell.

[0136] Fig. 14 is a diagram showing an example of system operation according to the third embodiment. In Fig. 14, non-essential steps are indicated by dashed lines. Furthermore, duplicated explanations of operations similar to those in the first embodiment will be omitted.

[0137] In step S301, the transmitting unit 120 of the UE 100 transmits a Measurement Report message, for example, on the PCell, to the node 200. The receiving unit 220 of the node 200 receives the Measurement Report message.

[0138] In step S302, the transmitting unit 210 of the node 200 transmits an RRC Reconfiguration message, for example, on the PCell, to the UE 100. The receiving unit 110 of the UE 100 receives the RRC Reconfiguration message.

[0139] In the third embodiment, the RRC Reconfiguration message may include setting information related to a Fast Tracking RS in addition to the information described in the first embodiment. The setting 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., resource block number, subcarrier number, and / or ARFCN (Absolute Radio-Frequency Channel Number)), and information assisting in demodulation of the Fast Tracking RS (e.g., a root sequence number indicating a signal sequence of a reference signal).

[0140] Alternatively, the node 200 may broadcast configuration information regarding the fast tracking RS in a system information block (SIB) of the PCell.

[0141] In step S303, the transmitting unit 210 of the UE 100 transmits an RRC Reconfiguration Complete message, for example, on the PCell, to the node 200. The receiving unit 220 of the node 200 receives the RRC Reconfiguration Complete message.

[0142] The initial state of the SCell added to the UE 100 may be an active state (step S304). Alternatively, after the SCell is added to the UE 100, the SCell may be activated by a MAC CE (step S304).

[0143] In step S305, the transmitter 210 of the node 200 transmits a fast tracking RS that is stationary on the time axis in the SCell that is the target of fast detection. The receiver 110 of the UE 100 receives the fast tracking RS on the SCell.

[0144] In step S306, the control unit 130 of the UE 100 measures the radio quality based on the Fast Tracking RS of the SCell.

[0145] In step S307, the control unit 130 of the UE 100 determines whether the wireless quality condition set in step S302 is satisfied. If it is determined that the wireless quality condition is not satisfied (step S307: NO), the process returns to step S306.

[0146] If it is determined that the radio quality condition is satisfied (step S307: YES), in step S308, the control unit 130 of the UE 100 deactivates the SCell.

[0147] In step S309, the transmitter 120 of the UE 100 transmits an SCell deactivation notification on the PCell to the node 200. The receiver 220 of the node 200 receives the SCell deactivation notification.

[0148] In step S310, the transmitter 210 of the node 200 transmits a HARQ ACK indicating successful reception of the SCell deactivation notification to the UE 100 on the PDCCH of the PCell. The receiver 110 of the UE 100 receives the HARQ ACK. Note that if the SCell deactivation notification is a UCI, step S308 does not need to be performed.

[0149] In step S311, the node 200 stops DL transmission to the UE 100 via the SCell.

[0150] (4) Other Embodiments The first to third embodiments described above may be implemented independently, or two or more of the embodiments may be combined and implemented.

[0151] In the above-described embodiment, an example in which the SCell is a THz-wave cell has been mainly described, but the SCell is not limited to a THz-wave cell. For example, the SCell may be an mmW cell.

[0152] The UE 100 may be a Mobile Termination (MT) of an Integrated Access and Backhaul (IAB) node. In this case, the IAB MT may be connected to a first node, and the first node may be connected to a second node. The first node may transmit a notification indicating a radio link failure of a backhaul link between the first node and the second node to the IAB MT. Upon receiving the notification, the IAB MT may determine that a radio quality condition is satisfied and may deactivate the SCell (or transition to dormant BWP).

[0153] The operational flows in the above-described embodiments do not necessarily have to be executed in chronological order according to the order shown in the flow diagrams. For example, the steps in the operations may be executed in an order different from that shown in the flow diagrams, or may be executed in parallel. Furthermore, some of the steps in the operations may be deleted, or additional steps may be added to the process.

[0154] A program may be provided that causes a computer (UE 100, node 200) to execute the operations according to the above-described embodiments. The program may be recorded on a computer-readable medium. Using the computer-readable medium, the program can be installed on a computer. Here, the computer-readable medium on which the program is recorded may be a non-transitory recording medium. The non-transitory recording medium is not particularly limited, and may be, for example, a recording medium such as a CD-ROM or a DVD-ROM.

[0155] 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 expressly stated otherwise. The term "based on" means both "based only on" and "based at least in part on." Similarly, the term "depending on" means both "depending only on" and "depending at least in part on." Furthermore, the terms "include," "comprise," and variations thereof do not mean including only the listed items, but may mean including only the listed items or may include additional items in addition to the listed items. Furthermore, the term "or," as used in this disclosure, is not intended to mean an exclusive or. Furthermore, any reference to elements using designations such as "first," "second," etc., as used in this disclosure does not generally limit the quantity or order of those elements. These designations may be used herein as a convenient method of distinguishing 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 way. In this disclosure, where articles are added by translation, such as a, an, and the in English, these articles shall include the plural unless the context clearly indicates otherwise.

[0156] 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 can be made within the scope that does not deviate from the gist of the invention.

[0157] (5) Supplementary Notes The following are additional notes regarding the features of the above-described embodiment.

[0158] (Supplementary Note 1) A user equipment that performs wireless communication with a node using carrier aggregation in a mobile communication system, comprising: a receiving unit that receives, from the node, information indicating a wireless quality condition that must be satisfied in order for the user equipment to perform a deactivation process for a secondary cell set in the user equipment; and a control unit that measures wireless quality and evaluates whether the wireless quality condition is satisfied, and the control unit executes the deactivation process for the secondary cell in response to the wireless quality condition being satisfied.

[0159] (Supplementary Note 2) The user equipment according to Supplementary Note 1, wherein the deactivation process includes a process of transitioning the secondary cell in an active state to a deactivated state.

[0160] (Supplementary Note 3) The user equipment according to Supplementary Note 1 or 2, wherein the deactivation process includes a process of transitioning a bandwidth portion in a non-dormant state in the secondary cell to a dormant state.

[0161] (Supplementary Note 4) The user equipment according to any one of Supplementary Notes 1 to 3, further comprising: a transmitter configured to transmit a notification regarding the deactivation process to the node in response to the wireless quality condition being satisfied.

[0162] (Supplementary Note 5) The user equipment according to Supplementary Note 4, wherein the transmitting unit transmits the notification to the node on a primary cell.

[0163] (Supplementary Note 6) The user equipment according to Supplementary Note 4 or 5, wherein the controller stops monitoring a physical downlink control channel (PDCCH) for the secondary cell when the radio quality condition is satisfied or when an acknowledgment to the notification is received from the node.

[0164] (Supplementary Note 7) The user equipment according to any one of Supplementary Notes 1 to 6, wherein the receiving unit receives a reference signal that is continuously transmitted in a time direction on the secondary cell from the node, and the control unit measures the radio quality based on the reference signal.

[0165] (Supplementary Note 8) A node that performs wireless communication with a user equipment using carrier aggregation in a mobile communication system, the node comprising: a control unit that sets a secondary cell in the user equipment; and a transmission unit that transmits to the user equipment information indicating a wireless quality condition that must be satisfied for the user equipment to perform a deactivation process for the secondary cell.

[0166] (Supplementary Note 9) The node according to Supplementary Note 8, wherein the deactivation process includes a process of transitioning the secondary cell in an active state to a deactive state.

[0167] (Supplementary Note 10) The node according to Supplementary Note 8 or 9, wherein the deactivation process includes a process of transitioning a bandwidth portion in a non-dormant state in the secondary cell to a dormant state.

[0168] (Supplementary Note 11) The node according to any one of Supplementary Notes 8 to 10, further comprising: a receiving unit configured to receive, in response to the wireless quality condition being satisfied in the user equipment, a notification regarding the deactivation process from the user equipment.

[0169] (Supplementary Note 12) The node according to Supplementary Note 11, wherein the receiving unit receives the notification from the user equipment on a primary cell.

[0170] (Supplementary Note 13) The node according to Supplementary Note 11 or 12, wherein the controller stops processing of downlink transmission on the secondary cell upon receiving the notification or upon transmitting an acknowledgement to the notification to the user equipment.

[0171] (Supplementary Note 14) The node according to any one of Supplementary Notes 8 to 13, wherein the transmitter transmits a reference signal used for measuring the radio quality continuously in a time direction on the secondary cell.

[0172] (Supplementary Note 15) A communication method used by a user equipment that performs wireless communication with a node using carrier aggregation in a mobile communication system, the communication method comprising: a step of receiving, from the node, information indicating a wireless quality condition that must be satisfied in order for the user equipment to perform a deactivation process for a secondary cell set in the user equipment; a step of measuring wireless quality and evaluating whether the wireless quality condition is satisfied; and a step of performing the deactivation process for the secondary cell in response to the wireless quality condition being satisfied.

[0173] (Supplementary Note 16) A communication method used in a node that performs wireless communication with a user equipment using carrier aggregation in a mobile communication system, the communication method comprising: a step of setting a secondary cell in the user equipment; and a step of transmitting to the user equipment information indicating a wireless quality condition that must be satisfied for the user equipment to perform a deactivation process for the secondary cell.

[0174] 1: Network 10: RAN 20: CN 100: UE 110: Receiving unit 120: Transmitting unit 130: Control unit 140: Wireless communication unit 200: Node 210: Transmitting unit 220: Receiving unit 230: Control unit 240: NW communication unit 250: Wireless communication unit 300: CN device

Claims

1. A user equipment that performs wireless communication with a node using carrier aggregation in a mobile communication system, comprising: a receiving unit that receives from the node information indicating a wireless quality condition that must be satisfied for the user equipment to perform a deactivation process for a secondary cell set in the user equipment; and a control unit that measures wireless quality and evaluates whether the wireless quality condition is satisfied, and the control unit executes the deactivation process for the secondary cell in response to the wireless quality condition being satisfied.

2. The user equipment according to claim 1, wherein the deactivation process includes a process of transitioning the secondary cell in an active state to a deactivated state.

3. The user equipment according to claim 1, wherein the deactivation process includes a process of transitioning a bandwidth portion in a non-dormant state in the secondary cell to a dormant state.

4. The user equipment according to claim 1, further comprising a transmission unit configured to transmit a notification regarding the deactivation process to the node in response to the wireless quality condition being satisfied.

5. The user equipment according to claim 4, wherein the transmission unit transmits the notification to the node on a primary cell.

6. The user equipment according to claim 4, wherein the control unit stops monitoring a physical downlink control channel (PDCCH) for the secondary cell when the radio quality condition is satisfied or when a positive response to the notification is received from the node.

7. The user equipment according to claim 1, wherein the receiving unit receives a reference signal transmitted continuously in a time direction from the node on the secondary cell, and the control unit measures the radio quality based on the reference signal.

8. A node that performs wireless communication with a user equipment using carrier aggregation in a mobile communication system, comprising: a control unit that sets a secondary cell in the user equipment; and a transmission unit that transmits to the user equipment information indicating a wireless quality condition that must be satisfied for the user equipment to perform a deactivation process for the secondary cell.

9. The node according to claim 8, wherein the deactivation process includes a process of transitioning the secondary cell in an active state to a deactivated state.

10. The node according to claim 8, wherein the deactivation process includes a process of transitioning a portion of bandwidth in the secondary cell that is in a non-dormant state to a dormant state.

11. The node according to claim 8, further comprising a receiving unit configured to receive, in response to the radio quality condition being satisfied in the user equipment, a notification regarding the deactivation process from the user equipment.

12. The node according to claim 11, wherein the receiver receives the notification from the user equipment on a primary cell.

13. The node according to claim 11, wherein the control unit stops processing downlink transmissions on the secondary cell upon receiving the notification or upon transmitting an acknowledgment to the notification to the user equipment.

14. The node according to claim 8, wherein the transmitting unit transmits a reference signal used for measuring the radio quality continuously in a time direction on the secondary cell.

15. A communication method used by a user equipment that performs wireless communication with a node using carrier aggregation in a mobile communication system, comprising the steps of: receiving information from the node indicating a wireless quality condition that must be satisfied for the user equipment to perform a deactivation process for a secondary cell set in the user equipment; measuring wireless quality and evaluating whether the wireless quality condition is satisfied; and performing the deactivation process for the secondary cell in response to the wireless quality condition being satisfied.

16. A communication method used in a node that performs wireless communication with a user equipment using carrier aggregation in a mobile communication system, the communication method comprising: a step of setting a secondary cell in the user equipment; and a step of transmitting to the user equipment information indicating a wireless quality condition that must be satisfied for the user equipment to perform a deactivation process for the secondary cell.

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