COMMUNICATION DEVICE, MASTER NODE, AND COMMUNICATION METHOD

Abstract

User equipment (UE) that performs communication with an MCG managed by a master node and an SCG managed by a secondary node has an MAC entity that is associated with the SCG. The MAC entity is a variable for uplink resource allocation to each logical channel used for communication with the SCG. The variable, for which the value changes with the passage of time, is managed for each logical channel. The UE performs, on the variable, a first process at reset of the MAC entity due to SCG inactivation, a second process while the SCG is in an inactive state, and a third process when activating the SCG.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is based on and claims the benefit of priority from patent application serial number 2022-001326, filed January 6, 2022, the entire contents of which are incorporated herein by reference. [Technical Field]

[0002] The present disclosure relates to a communication device and a communication method used in a mobile communication system. [Background technology]

[0003] Dual connectivity (DC) has been introduced in mobile communication systems that comply with the technical specifications of 3GPP (Third Generation Partnership Project, a registered trademark; the same applies hereinafter), a standardization project for mobile communication systems. In DC, a communication device (UE: User Equipment) communicates with a master cell group (MCG) managed by a master node (also called a "master base station") and a secondary cell group (SCG) managed by a secondary node (also called a "secondary base station").

[0004] 3GPP is studying a technique for temporarily deactivating an SCG set in a communication device in order to reduce power consumption of the communication device in DC. For example, a master node instructs the communication device to activate or deactivate the SCG. When the SCG is inactive, communication between the communication device and the SCG is stopped, thereby reducing power consumption of the communication device.

[0005] Meanwhile, the 3GPP technical specifications prescribe logical channel prioritization (LCP) (see Non-Patent Documents 1 to 3). Specifically, a medium access control (MAC) entity of a communication device manages, for each logical channel, a variable for allocating uplink resources to each logical channel, the variable being increased over time. In the 3GPP technical specifications, such a variable for each logical channel "j" is called "Bj." Every time the communication device performs uplink transmission, it allocates uplink resources to each logical channel using the managed variable Bj. [Prior art documents] [Non-patent literature]

[0006] [Non-Patent Document 1] 3GPP Technical Specification: TS 38.321 V16.7.0 [Non-patent document 2] 3GPP contribution: R2-2111638 [Non-patent document 3] 3GPP contribution: R2-2111314 Summary of the Invention

[0007] The communication device deactivates the SCG in response to receiving an instruction to deactivate the SCG, and then activates the SCG in response to receiving an instruction to activate the SCG. It is not yet determined how to control the LCP in such operations.

[0008] According to the current 3GPP technical specifications, even if the SCG is inactive and the communication device has no data to transmit to the SCG, the value of the variable Bj in the LCP may increase. When the SCG is subsequently activated, the LCP is performed with the variable Bj already accumulated. Therefore, there is a concern that an inappropriate LCP may be performed when the SCG is switched from an inactive state to an active state.

[0009] Therefore, the present disclosure provides a communication device and a communication method that are capable of performing an appropriate LCP when an SCG is switched from an inactive state to an active state.

[0010] A communication device according to a first aspect communicates with a master cell group (MCG) managed by a master node and a secondary cell group (SCG) managed by a secondary node, and includes a controller having a medium access control (MAC) entity associated with the SCG. The MAC entity manages, for each logical channel, a variable for uplink resource allocation for each logical channel used for communication with the SCG, the variable increasing in value over time. The controller performs a first process for the variable when the MAC entity is reset due to deactivation of the SCG, a second process while the SCG is in the inactive state, and a third process when the SCG is activated.

[0011] A communication method according to a second aspect is a communication method for communicating with a master cell group (MCG) managed by a master node and a secondary cell group (SCG) managed by a secondary node, and includes the steps of: a medium access control (MAC) entity associated with the SCG managing, for each logical channel, a variable for allocating uplink resources to each logical channel used for communication with the SCG, the variable increasing in value over time; and performing a first process on the variable when the MAC entity is reset due to deactivation of the SCG, a second process while the SCG is in the inactive state, and a third process when the SCG is activated. [Brief explanation of the drawings]

[0012] The above and other objects, features and advantages of the present disclosure will become more apparent from the following detailed description taken in conjunction with the accompanying drawings, in which: [Figure 1]FIG. 1 is a diagram showing a configuration of a mobile communication system according to an embodiment; [Figure 2] FIG. 2 is a diagram illustrating an example of a configuration of a protocol stack in a mobile communication system according to an embodiment; [Figure 3] FIG. 3 is a diagram for explaining an overview of BFD and BFR according to the embodiment, showing internal processing of a UE; [Figure 4] FIG. 4 is a diagram for explaining an overview of BFD and BFR according to an embodiment, illustrating an example in which a beam failure is detected in a PCell; [Figure 5] FIG. 5 is a diagram for explaining an overview of BFD and BFR according to an embodiment, illustrating an example in which a beam failure is detected in an SCell; [Figure 6] FIG. 6 is a diagram illustrating an overview of an LCP according to an embodiment; [Figure 7] FIG. 7 is a diagram for explaining an overview of a DC according to an embodiment; [Figure 8] FIG. 8 is a diagram illustrating a configuration of a UE according to an embodiment; [Figure 9] FIG. 9 is a diagram showing a configuration of a base station according to the embodiment; [Figure 10] FIG. 10 is a diagram illustrating a first operation example regarding BFD and BFR according to the embodiment; [Figure 11] FIG. 11 is a diagram illustrating a second operation example regarding BFD and BFR according to the embodiment; [Figure 12] FIG. 12 is a diagram illustrating a third operation example regarding BFD and BFR according to the embodiment; [Figure 13] FIG. 13 is a diagram illustrating a fourth operation example regarding BFD and BFR according to the embodiment; [Figure 14] FIG. 14 is a diagram illustrating a first operation example of an LCP according to an embodiment; [Figure 15] FIG. 15 is a diagram illustrating a second operation example of the LCP according to the embodiment; [Figure 16]FIG. 16 is a diagram illustrating a third operation example of the LCP according to the embodiment; [Figure 17] FIG. 17 is a diagram illustrating a fourth operation example of the LCP according to the embodiment; [Figure 18] FIG. 18 is a diagram illustrating an example of a change in the specifications of a MAC reset according to an embodiment; [Figure 19] FIG. 19 is a diagram illustrating an example of a change in the specifications of a MAC reset according to an embodiment; [Figure 20] FIG. 20 is a diagram illustrating an example of a change in the specifications of a MAC reset according to an embodiment; [Figure 21] FIG. 21 is a diagram illustrating an example of a change in specifications of BFD and BFR (Beam Failure Detection and Recovery procedure) according to an embodiment; [Figure 22] FIG. 22 is a diagram illustrating an example of a change in specifications of BFD and BFR (Beam Failure Detection and Recovery procedure) according to an embodiment; [Figure 23] FIG. 23 is a diagram illustrating an example of a change in specifications of BFD and BFR (Beam Failure Detection and Recovery procedure) according to an embodiment; [Figure 24] FIG. 24 is a diagram illustrating an example of a change in the specification of LCP (Logical Channel Prioritization) according to the embodiment; [Figure 25] FIG. 25 is a diagram showing variations of the DC according to the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0013] 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] (Configuration of a mobile communication system) First, with reference to FIG. 1, the configuration of a mobile communication system 1 according to an embodiment will be described.

[0015] The mobile communication system 1 is, for example, a system that complies with the 3GPP Technical Specification (TS). In the following, the mobile communication system 1 will be mainly described as a mobile communication system based on NR (NR Radio Access), which is the radio access technology (RAT) of the 3GPP fifth generation (5G) system. However, the mobile communication system 1 may also have a configuration that is at least partially based on E-UTRA (Evolved Universal Terrestrial Radio Access) / LTE (Long Term Evolution), which is the RAT of the 3GPP fourth generation (4G) system.

[0016] The mobile communication system 1 includes a network 10 and a communication device (User Equipment: UE) 100 that communicates with the network 10. The network 10 includes a radio access network (RAN) 20 and a core network (CN) 30. The RAN 20 is a next generation radio access network (NG-RAN) in 5G / NR. The RAN 20 may be an evolved universal terrestrial radio access network (E-UTRAN) in 4G / LTE. The CN 30 is a fifth generation core network (5GC) in 5G / NR. The CN 30 may be an evolved packet core (EPC) in 4G / LTE.

[0017] The UE 100 is a device used by a user. The UE 100 is a mobile device, such as a mobile phone terminal such as a smartphone, a tablet terminal, a laptop PC, a communication module, or a communication card. The UE 100 may be a vehicle (e.g., a car, a train, etc.) or a device provided therein. The UE 100 may be a transport vehicle other than a vehicle (e.g., a ship, an airplane, etc.) or a device provided therein. The UE 100 may be a sensor or a device provided therein. Note that the UE 100 may be called by other names such as a mobile station, a mobile terminal, a mobile device, a mobile unit, a subscriber station, a subscriber terminal, a subscriber device, a subscriber unit, a wireless station, a wireless terminal, a wireless device, a wireless unit, a remote station, a remote terminal, a remote device, or a remote unit.

[0018] The RAN 20 includes multiple base stations 200. Each base station 200 manages at least one cell. A cell constitutes the smallest unit of a communication area. For example, one cell belongs to one frequency (carrier frequency) and is composed of one component carrier. The term "cell" may refer to wireless communication resources or to a communication target of the UE 100. Each base station 200 can perform wireless communication with the UE 100 located in its own cell. The base station 200 communicates with the UE 100 using a protocol stack of the RAN. The base station 200 provides user plane and control plane protocol terminations for the UE 100 and is connected to the CN 30 via a base station-CN network interface. The base station 200 in 5G / NR is called a gNodeB (gNB), and the base station 200 in 4G / LTE is called an eNodeB (eNB). The base station-CN interface in 5G / NR is called an NG interface, and the base station-CN interface in 4G / LTE is called an S1 interface. Base station 200 is connected to neighboring base stations via a network interface between base stations. The interface between base stations in 5G / NR is called an Xn interface, and the interface between base stations in 4G / LTE is called an X2 interface.

[0019] The CN 30 includes a core network device 300. The core network device 300 is an Access and Mobility Management Function (AMF) and / or a User Plane Function (UPF) in 5G / NR. The core network device 300 may be a Mobility Management Entity (MME) and / or a Serving Gateway (S-GW) in 4G / LTE. The AMF / MME performs mobility management for the UE 100. The UPF / S-GW provides functions specialized for user plane processing.

[0020] Next, with reference to FIG. 2, an example of the configuration of a protocol stack in the mobile communication system 1 according to the embodiment will be described.

[0021] The protocol for the wireless section between the UE 100 and the base station 200 includes 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 radio resource control (RRC) layer.

[0022] 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 the UE 100 and the PHY layer of the base station 200 via a physical channel.

[0023] A physical channel consists of multiple OFDM symbols in the time domain and multiple subcarriers in the frequency domain. One subframe consists of multiple OFDM symbols in the time domain. A resource block is a resource allocation unit and consists of multiple OFDM symbols and multiple subcarriers. A frame can be configured for 10 ms and can include 10 subframes, each of which is 1 ms long. A subframe can include the number of slots corresponding to the subcarrier spacing.

[0024] Among physical channels, the physical downlink control channel (PDCCH) plays a central role for purposes such as downlink scheduling assignment, uplink scheduling grant, and transmit power control. For example, the UE 100 performs blind decoding of the PDCCH using a Cell-Radio Network Temporary Identifier (C-RNTI) and a Modulation and Coding Scheme-C-RNTI (MCS-C-RNTI) or a Configured Scheduling-RNTI (CS-RNTI) assigned to the UE 100 by the base station 200, and acquires successfully decoded DCI as DCI addressed to the UE. Here, CRC parity bits scrambled by the C-RNTI and the MCS-C-RNTI or the CS-RNTI are added to the DCI transmitted from the base station 200.

[0025] In NR, the UE 100 can use a bandwidth narrower than the system bandwidth (i.e., the cell bandwidth). The base station 200 configures the UE 100 with a bandwidth part (BWP) consisting of consecutive PRBs. The UE 100 transmits and receives data and control signals in an active BWP. For example, up to four BWPs can be configured for the UE 100. Each BWP may have a different subcarrier spacing. Furthermore, the frequencies of the BWPs may overlap with each other. When multiple BWPs are configured for the UE 100, the base station 200 can specify which BWP to activate by controlling downlink. This allows the base station 200 to dynamically adjust the UE bandwidth according to the amount of data traffic of the UE 100, thereby reducing UE power consumption.

[0026] For example, base station 200 can configure up to three control resource sets (CORESETs) for each of up to four BWPs on the serving cell. A CORESET is a radio resource for control information to be received by UE 100. Up to 12 CORESETs can be configured for UE 100 on the serving cell. Each CORESET has an index of 0 to 11. For example, a CORESET consists of six resource blocks (PRBs) and one, two, or three consecutive OFDM symbols in the time domain.

[0027] The MAC layer performs data priority control, retransmission processing using Hybrid Automatic Repeat reQuest (HARQ), random access procedures, etc. Data and control information are transmitted between the MAC layer of UE 100 and the MAC layer of base station 200 via a transport channel. The MAC layer of base station 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.

[0028] The RLC layer transmits data to the RLC layer on the receiving side using the functions of the MAC layer and PHY layer. Data and control information are transmitted between the RLC layer of the UE 100 and the RLC layer of the base station 200 via logical channels.

[0029] The PDCP layer performs header compression / decompression and encryption / decryption.

[0030] A Service Data Adaptation Protocol (SDAP) layer may be provided above the PDCP layer. The SDAP layer maps IP flows, which are units for Quality of Service (QoS) control in the core network, to radio bearers, which are units for QoS control in the Access Stratum (AS).

[0031] The RRC layer controls logical channels, transport channels, and physical channels according to the establishment, re-establishment, and release of radio bearers. RRC signaling for various settings is transmitted between the RRC layer of the UE 100 and the RRC layer of the base station 200. When there is an RRC connection between the RRC of the UE 100 and the RRC of the base station 200, the UE 100 is in an RRC connected state. When there is no RRC connection between the RRC of the UE 100 and the RRC of the base station 200, the UE 100 is in an RRC idle state. When the RRC connection between the RRC of the UE 100 and the RRC of the base station 200 is suspended, the UE 100 is in an RRC inactive state.

[0032] A Non-Access Stratum (NAS) layer located above the RRC layer performs session management and mobility management for the UE 100. NAS signaling is transmitted between the NAS layer of the UE 100 and the NAS layer of the core network device 300 (AMF / MME). Note that the UE 100 also has an application layer and the like in addition to a radio interface protocol.

[0033] (Outline of BFD and BFR) Next, an overview of beam failure detection (BFD) and beam failure recovery (BFR) according to the embodiment will be described with reference to FIGS.

[0034] Compared to 4G / LTE, 5G / NR is capable of wideband transmission using high frequency bands such as the millimeter wave band or terahertz wave band. In 5G / NR, to compensate for radio wave attenuation in such high frequency bands, high beam gain is achieved by using highly directional beamforming with multiple antennas between the base station 200 and the UE 100. NR introduces beam control technologies for establishing and maintaining beam pairs between the base station 200 and the UE 100. BFD and BFR are examples of such beam control technologies.

[0035] Regarding BFD, the base station 200 configures the UE 100 with downlink reference signal resources for detecting beam failure. Such reference signal resources are either SSBs (SS / PBCH Blocks) or CSI-RSs (Channel State Information Reference Signals). The SSBs include a Primary Synchronization Signal (PSS), a Secondary Synchronization Signal (SSS), a PBCH (Physical Broadcast Channel), and a Demodulation Reference Signal (DMRS). For example, an SSB may consist of four consecutive OFDM symbols in the time domain. Alternatively, an SSB may consist of 240 consecutive subcarriers (i.e., 20 resource blocks) in the frequency domain. The PBCH is a physical channel that carries a Master Information Block (MIB). The CSI-RS is a reference signal transmitted so that the UE 100 can measure the state of the wireless channel.

[0036] As shown in FIG. 3, in UE 100, the MAC layer (MAC entity) manages a BFI (Beam Failure Instance) counter and a BFD timer for each serving. Parameters (e.g., a BFI counter and / or a BFD timer) managed by the MAC entity to perform BFD are referred to as BFD parameters. The MAC entity of UE 100 counts beam failure events (beam failure instance indicators) notified from the PHY layer for a serving cell using a BFI counter, and detects (recognizes) a beam failure for the serving cell when the count value of the BFI counter becomes equal to or greater than a threshold before the BFD timer expires. The BFD timer is a timer that starts or restarts when the MAC entity receives a beam failure instance indicator. Note that the threshold value of the BFI counter and the timer setting value of the BFD timer are configured in UE 100 by the network 10. When the MAC entity of UE 100 detects a beam failure, it performs BFR to recover from the beam failure.

[0037] FIG. 4 shows an example in which a beam failure is detected in a primary cell (PCell) serving as a serving cell. FIG. 4 shows an example in which a PSCell has a total of three beams, beam #0 to beam #2. A MAC entity of UE 100 detects a beam failure during communication using a certain beam (e.g., beam #0) in the PSCell. In this case, the MAC entity of UE 100 triggers BFR by initiating a random access procedure for the PCell. Here, the MAC entity of UE 100 starts a BFR timer that determines the period for attempting random access. Then, the MAC entity of UE 100 selects an appropriate beam (e.g., beam #1) to perform BFR. When this random access procedure is completed, BFR is completed.

[0038] FIG. 5 shows an example in which a beam failure is detected in a secondary cell (SCell) serving as a serving cell. FIG. 5 shows an example in which the SCell has a total of three beams, beam #0 to beam #2. The MAC entity of UE 100 detects a beam failure in the SCell during communication using a certain beam (e.g., beam #0). In this case, UE 100 triggers BFR by starting transmission of a BFR MAC CE. Here, the MAC entity of UE 100 selects a beam suitable for the SCell (e.g., beam #1) and indicates the selected beam information together with information about the beam failure in the BFR MAC CE. When the MAC entity of UE 100 receives a PDCCH indicating an uplink grant for a new transmission of the HARQ process used to transmit the BFR MAC CE, BFR for SCell 250B is completed.

[0039] (LCP Overview) Next, an overview of logical channel prioritization (LCP) according to the embodiment will be described with reference to FIG.

[0040] In the uplink, the MAC entity of UE 100 performs LCP when generating a MAC PDU (Protocol Data Unit) to be transmitted using radio resources allocated by base station 200. Based on the uplink grant notified by the PDCCH, the MAC entity of UE 100 determines the amount of data for each logical channel to be included in the new MAC PDU in accordance with the priority of each logical channel so as to satisfy the QoS (Quality of Service) required for each configured radio bearer (each logical channel). Such an LCP procedure is applied when a new transmission is performed.

[0041] As shown in Figure 6, the MAC entity of the UE 100 stores data in the MAC PDU in descending order of priority for logical channels until the available MAC PDU size is reached. The network 10 (RRC) configures the UE 100 with a priority, a prioritized bit rate (PBR), and a bucket size period (BSD) for each logical channel to control the scheduling of uplink data for each logical channel. Here, the higher the priority value, the lower the priority.

[0042] The MAC entity of the UE 100 also manages a variable Bj for each logical channel j. Bj is initialized to zero when the corresponding logical channel is established and is incremented by PBR×T, where PBR is the prioritized bit rate of the logical channel j and T is the time elapsed since Bj was last incremented. However, the value of Bj cannot exceed the bucket size, which is equal to PBR×BSD. If the value of Bj is greater than the bucket size of the logical channel j, the MAC entity of the UE 100 sets the value of Bj to the bucket size.

[0043] The MAC entity of the UE 100 then allocates resources for the selected logical channels with Bj>0 in descending order of priority. Note that if the PBR of a logical channel is set to infinity, the MAC entity allocates resources to all data available for transmission on the logical channel with PBR set to infinity before satisfying the PBR of a logical channel with a lower priority. The MAC entity also reduces Bj by the total size of data (MAC SDUs) provided to logical channel j. If resources remain, all selected logical channels are provided with resources in descending order of priority until either the data or uplink grant for that logical channel is exhausted.

[0044] (DC Overview) Next, an overview of the DC according to the embodiment will be described with reference to FIG.

[0045] In the DC, the UE 100 communicates with a master cell group (MCG) 201M managed by a master node (MN) 200M and a secondary cell group (SCG) 201S managed by a secondary node (SN) 200S. The MN 200M and the SN 200S are connected to each other via a network interface. The network interface between the MN 200M and the SN 200 may be an Xn interface or an X2 interface. The MN 200M and the SN 200 communicate with each other via the network interface. Note that the MN 200M may be referred to as a master base station. The SN 200S may be referred to as a secondary base station.

[0046] For example, DC is initiated when MN 200M transmits a predetermined message (for example, an SN Addition Request message) to SN 200S, and MN 200M transmits an RRC Reconfiguration message to UE 100. In DC, UE 100 in the RRC connected state is assigned radio resources by the respective schedulers of MN 200M and SN 200S, and performs radio communication using the radio resources of MN 200M and SN 200S.

[0047] The MN 200M may have a control plane connection with a core network. The MN 200M provides primary radio resources for the UE 100. The MN 200M manages the MCG 201M. The MCG 201M is a group of serving cells associated with the MN 200M. The MCG 201M has a primary cell (PCell) and optionally has one or more secondary cells (SCells).

[0048] The SN200S may not have a control plane connection with the core network. The SN200S provides additional radio resources to the UE100. The SN200S manages the SCG201S. The SCG201S has a primary and secondary cell (PSCell) and optionally has one or more SCells. The PCell of the MCG201M and the PSCell of the SCG201S are sometimes referred to as special cells (SpCells).

[0049] In this way, in the DC, the roles of the nodes that communicate with the UE 100 are divided into the MN 200M and the SN 200S. Except for the settings that are determined independently by the SN 200S, the MN 200M has the initiative to determine the settings for the UE 100.

[0050] Also, in DC, two MAC entities 101M and 101S are configured in the UE 100. One is the MAC entity 101M for the MCG 201M, and the other is the MAC entity 101S for the SCG 201S. The serving cells of the MCG 201M other than the PCell can be activated / deactivated by a MAC control element (CE) received by the MCG 201M. The serving cells of the SCG 201S other than the PSCell can be activated / deactivated by a MAC CE received by the SCG 201S. The PSCell of the SCG 201S is always in an activated state (active state), similar to the PCell.

[0051] Currently, 3GPP is studying a technology for activating / deactivating on an SCG 201S basis configured in the UE 100, rather than on a serving cell basis as described above. When the SCG 201S is in an inactive state, all serving cells (PSCells and SCells) belonging to the SCG 201S are in an inactive state. For example, the MN 200M transmits an RRC message to the UE 100 to instruct (set) activation or deactivation of the SCG 201S. Such an RRC message may be an RRC Reconfiguration message. The UE 100 activates or deactivates the SCG 201S in response to receiving the instruction.

[0052] The inactive state of the SCG201S may be a state in which the UE100 does not transmit at least one of CSI (Channel Status Information), SRS (Sounding Reference Signal), and UL-SCH (UL-Shared CHannel) for each serving cell (particularly, PSCell) belonging to the inactive SCG201S, and / or a state in which the UE100 does not monitor PDCCH (Physical Downlink Control Channel). When the SCG201S is in the inactive state, communication between the UE100 and the SCG201S is stopped, so that power consumption of the UE100 is reduced.

[0053] In the current discussions in 3GPP, it is agreed that the network 10 (for example, the MN 200M) can configure the UE 100 to perform BFD for the SCG 201S (particularly, the PSCell) when the SCG 201S is in an inactive state. In addition, in the current discussions in 3GPP, it is considered to reset the MAC entity when the SCG 201S is in an inactive state. Note that the conventional MAC reset process is executed at the time of RRC Reconfiguration, etc., and is a process of resetting MAC parameters, and for example, the following is executed: ·Stop all timers managed by the MAC entity; Cancelling SR (Scheduling Request), BSR (Buffer Status Report), PHR (Power Headroom Report), BFR, etc. that are being executed by the MAC entity; · Zero (i.e. reset) counters managed by the MAC entity (including the BFI counter).

[0054] When UE100 is configured to perform BFD for SCG201S (particularly, PSCell) when SCG201S is inactive, if UE100 resets the BFD parameters (particularly, the BFI count value) when deactivating SCG201S, the detection state in BFD up to that point is initialized. As a result, BFD after SCG201S becomes inactive is delayed, and a low-quality beam is set during that time. Therefore, the current method of deactivating SCG201S has room for improvement in terms of efficiently performing BFD when SCG201S is inactive.

[0055] Furthermore, a method for controlling LCP in a series of operations in which UE 100 deactivates SCG 201S and then activates SCG 201S is not yet determined. According to the current 3GPP technical specifications, even if SCG 201S is in an inactive state and UE 100 does not have data to transmit to SCG 201S, the value of variable Bj in LCP may increase. When SCG 201S is subsequently activated, LCP is performed with variable Bj already accumulated. Therefore, there is a concern that inappropriate LCP may be performed when SCG 201S is switched from an inactive state to an active state.

[0056] (UE configuration) Next, a configuration of the UE 100 according to the embodiment will be described with reference to Fig. 8. The UE 100 includes a communication unit 110 and a control unit 120.

[0057] The communication unit 110 performs wireless communication with the base station 200 by transmitting and receiving radio signals to and from the base station 200. The communication unit 110 has at least one transmission unit 111 and at least one reception unit 112. The transmission unit 111 and the reception unit 112 may be configured to include multiple antennas and RF circuits. The antenna converts a signal into radio waves and radiates the radio waves into space. The antenna also receives radio waves in space and converts the radio waves into a signal. The RF circuit performs analog processing of the signal transmitted and received via the antenna. The RF circuit may include a high-frequency filter, an amplifier, a modulator, a low-pass filter, etc.

[0058] The control unit 120 performs various controls in the UE 100. The control unit 120 controls communication with the base station 200 via the communication unit 110. The operations of the UE 100 described above and below may be controlled by the control unit 120. The control unit 120 may include at least one processor capable of executing a program and a memory that stores the program. The processor may execute the program to perform the operations of the control unit 120. The control unit 120 may include a digital signal processor that performs digital processing of signals transmitted and received via the antenna and the RF circuit. The digital processing includes processing of a RAN protocol stack. The memory stores programs executed by the processor, parameters related to the programs, and data related to the programs. The memory may include at least one of a read-only memory (ROM), an erasable programmable read-only memory (EPROM), an electrically erasable programmable read-only memory (EEPROM), a random access memory (RAM), and a flash memory. All or a part of the memory may be included in the processor.

[0059] The UE 100 configured in this manner performs DC communication with the MCG 201M and the SCG 201S (see FIG. 7). The control unit 120 has a MAC entity 101S associated with the SCG 201S. The receiving unit 112 receives an SCG deactivation instruction to deactivate the SCG 201S. The receiving unit 112 may receive an RRC message including the SCG deactivation instruction from the MN 200M (MCG 201M). The MAC entity 101S manages BFD parameters for performing BFD for the SCG 201S (particularly, the PSCell). If the SCG 201S is configured to perform BFD when it is in the deactivation state, the control unit 120 performs processing to reset the MAC entity 101S while maintaining the BFD parameters in response to receiving the SCG deactivation instruction. As a result, the BFD parameters (e.g., BFI count value, BFD timer) are not reset when the SCG 201S is deactivated, and the detection state in BFD up to that point continues. As a result, BFD can be performed quickly after the SCG201S enters the inactive state to detect beam faults. In other words, even after entering the SCG inactive state, BFD and BFR can be performed in the same state as before, preventing execution delays. Therefore, BFD can be performed efficiently when the SCG201S is in the inactive state. Hereinafter, the process of partially resetting MAC parameters when deactivating the SCG201S is also referred to as a "partial MAC reset."

[0060] On the other hand, if the SCG 201S is not set to perform BFD when in the inactive state, the control unit 120 may reset or stop the BFD parameters and reset the MAC entity 101S in response to receiving the SCG deactivation instruction. In this way, by resetting or stopping the BFD parameters, the processing load of the UE 100 can be reduced.

[0061] Furthermore, in the UE 100, the MAC entity 101S associated with the SCG 201S manages, for each logical channel, a variable Bj, which is a variable for allocating uplink resources to each logical channel used for communication with the SCG 201S and whose value increases over time. The control unit 120 performs a first process for the variable Bj when the SCG 201S is in an inactive state, a second process while the SCG 201S is in the inactive state, and a third process when the SCG 201S is in an active state. Here, the control unit 120 performs the first to third processes so that the value of the variable Bj becomes zero when the SCG 201S is in an active state. Because the value of the variable Bj becomes zero when the SCG 201S is in an active state, it is possible to avoid LCP being performed with the variable Bj already accumulated when the SCG 201S is switched from the inactive state to the active state. Therefore, it is possible to perform appropriate LCP when the SCG 201S is switched from the inactive state to the active state.

[0062] At least some of the first to third processes may be different from the other processes. The first process may be a process performed upon a partial reset of the MAC entity 101S. The third process may be a process performed upon a reset of the MAC entity 101S.

[0063] (Base station configuration) Next, the configuration of the base station 200 according to the embodiment will be described with reference to Fig. 9. The base station 200 includes a communication unit 210, a network interface 220, and a control unit 230.

[0064] The communication unit 210 receives a radio signal from the UE 100 and transmits the radio signal to the UE 100, for example. The communication unit 210 has at least one transmission unit 211 and at least one reception unit 212. The transmission unit 211 and the reception unit 212 may be configured to include an RF circuit. The RF circuit performs analog processing of a signal transmitted and received via an antenna. The RF circuit may include a high-frequency filter, an amplifier, a modulator, a low-pass filter, etc.

[0065] The network interface 220 transmits and receives signals to and from the network. For example, the network interface 220 receives signals from adjacent base stations connected via an Xn interface, which is an interface between base stations, and transmits signals to the adjacent base stations. The network interface 220 also receives signals from the core network device 300 connected via an NG interface, and transmits signals to the core network device 300.

[0066] The control unit 230 performs various controls in the base station 200. The control unit 230 controls, for example, communication with the UE 100 via the communication unit 210. The control unit 230 also controls, for example, communication with a node (e.g., a neighboring base station, the core network device 300) via the network interface 220. The operations of the base station 200 described above and below may be operations controlled by the control unit 230. The control unit 230 may include at least one processor capable of executing a program and a memory that stores the program. The processor may execute the program to perform the operations of the control unit 230. The control unit 230 may include a digital signal processor that performs digital processing of signals transmitted and received via the antenna and the RF circuit. The digital processing includes processing of a protocol stack of the RAN. The memory stores the program executed by the processor, parameters related to the program, and data related to the program. All or a part of the memory may be included in the processor.

[0067] (Example of UE operation) (1) Example of BFD and BFR operation Next, first to fourth operation examples of the UE 100 related to BFD and BFR according to the embodiment will be described with reference to Fig. 10 to Fig. 13. These first to fourth operation examples may be implemented independently of each other, or two or more operation examples may be combined and implemented.

[0068] (1.1) First example of BFD and BFR operation The BFD parameters managed by the MAC entity 101S for the SCG 201S include a count value (BFI counter) that counts beam failure instance indicators notified to the MAC entity 101S from the physical layer of the UE 100. The MAC entity 101S detects a beam failure when the count value of the BFI counter reaches a threshold. If BFD is configured to be performed when the SCG 201S is in an inactive state, the control unit 120 of the UE 100 performs processing to reset the MAC entity 101S without resetting the count value of the BFI counter in response to receiving an SCG deactivation instruction. This maintains the count value of the BFI counter before the SCG 201S is deactivated, making it possible to quickly detect a beam failure after the SCG 201S is deactivated.

[0069] On the other hand, if the SCG 201S is not set to perform BFD when it is in an inactive state, the control unit 120 of the UE 100 resets the count value of the BFI counter and resets the MAC entity 101S in response to receiving the SCG deactivation instruction. By resetting the count value of the BFI counter, it is possible to reduce the memory usage and processing load of the UE 100 and prevent the occurrence of unexpected errors.

[0070] FIG. 10 is a flow diagram showing this operation example.

[0071] In step S11, the control unit 120 of the UE 100 (specifically, the MAC entity 101S for the SCG 201S) manages a BFI counter for each serving cell included in the SCG 201S.

[0072] In step S12, the receiving unit 112 of the UE 100 receives an SCG deactivation instruction from, for example, the MN 200M (MCG 201M).

[0073] In step S13, the control unit 120 of the UE 100 determines whether or not the UE 100 is configured to perform BFD in the SCG inactive state. For example, when the receiving unit 112 receives an RRC message including configuration information for setting the UE 100 to perform BFD in the SCG inactive state from, for example, the MN 200M (MCG 201M), the control unit 120 of the UE 100 may determine that the UE 100 is configured to perform BFD in the SCG inactive state.

[0074] If it is determined that BFD is configured to be performed in the SCG inactive state (step S13: YES), in step S14, the control unit 120 of the UE 100 performs a process of resetting the MAC entity 101S without resetting the count value of the BFI counter in response to receiving the SCG deactivation instruction.

[0075] On the other hand, if it is determined that BFD is not configured to be performed in the SCG inactive state (step S13: NO), in step S15, the control unit 120 of UE 100 resets the count value of the BFI counter and performs processing to reset the MAC entity 101S in response to receiving the SCG deactivation instruction.

[0076] (1.2) Second example of operation regarding BFD and BFR The BFD parameters managed by the MAC entity 101S for the SCG 201S include a BFD timer for BFD. The MAC entity 101S detects a beam failure in response to the count value of the BFI counter reaching a threshold before the expiration of the BFD timer. If the SCG 201S is configured to perform BFD when it is in an inactive state, the control unit 120 of the UE 100 performs processing to reset the MAC entity 101S without stopping the BFD timer in response to receiving an SCG deactivation instruction. In this way, by not stopping the BFD timer, BFD can be performed appropriately even if the SCG 201S is deactivated.

[0077] On the other hand, if the SCG 201S is not set to perform BFD when it is in an inactive state, the control unit 120 of the UE 100 stops the BFD timer and resets the MAC entity 101S in response to receiving the SCG deactivation instruction. By stopping the BFD timer, it is possible to reduce the processing load of the UE 100 and prevent the occurrence of unexpected errors.

[0078] 11 is a flow diagram showing this operation example. Here, differences from the first operation example regarding the BFD and BFR described above will be mainly explained, and overlapping explanations will be omitted.

[0079] In step S21, the control unit 120 of the UE 100 (specifically, the MAC entity 101S for the SCG 201S) manages the BFD timer for each serving cell included in the SCG 201S.

[0080] In step S22, the receiving unit 112 of the UE 100 receives an SCG deactivation instruction from, for example, the MN 200M (MCG 201M).

[0081] In step S23, the control unit 120 of the UE 100 determines whether or not it is set to perform BFD in the SCG inactive state.

[0082] If it is determined that BFD is configured to be performed in the SCG inactive state (step S23: YES), in step S24, the control unit 120 of the UE 100 performs a process of resetting the MAC entity 101S without stopping the BFD timer in response to receiving the SCG deactivation instruction.

[0083] On the other hand, if it is determined that BFD is not configured to be performed in the SCG inactive state (step S23: NO), in step S25, the control unit 120 of UE 100 stops the BFD timer and performs processing to reset the MAC entity 101S in response to receiving the SCG deactivation instruction.

[0084] (1.3) Third example of operation regarding BFD and BFR The MAC entity 101S for the SCG 201S manages a BFR timer for performing BFR when a beam failure is detected by BFD. If the SCG 201S is configured to perform BFD when it is in an inactive state, the control unit 120 of the UE 100 performs processing to reset the MAC entity 101S without stopping the BFR timer in response to receiving an SCG deactivation instruction. By not stopping the BFR timer, it is possible to properly perform BFR even when the SCG 201S is deactivated.

[0085] On the other hand, if the SCG 201S is not set to perform BFD when it is in an inactive state, the control unit 120 of the UE 100 stops the BFR timer and resets the MAC entity 101S in response to receiving the SCG deactivation instruction. By stopping the BFR timer, it is possible to reduce the processing load of the UE 100 and prevent the occurrence of unexpected errors.

[0086] 12 is a flow diagram showing this operation example. Here, differences from the first operation example regarding the BFD and BFR described above will be mainly explained, and overlapping explanations will be omitted.

[0087] In step S31, the control unit 120 of the UE 100 (specifically, the MAC entity 101S for the SCG 201S) manages a BFR timer for each serving cell included in the SCG 201S.

[0088] In step S32, the receiving unit 112 of the UE 100 receives an SCG deactivation instruction from, for example, the MN 200M (MCG 201M).

[0089] In step S33, the control unit 120 of the UE 100 determines whether or not it is set to perform BFD in the SCG inactive state.

[0090] If it is determined that BFD is configured to be performed in the SCG inactive state (step S33: YES), in step S34, the control unit 120 of the UE 100 performs a process of resetting the MAC entity 101S without stopping the BFR timer in response to receiving the SCG deactivation instruction.

[0091] On the other hand, if it is determined that BFD is not configured to be performed in the SCG inactive state (step S33: NO), in step S35, the control unit 120 of UE 100 stops the BFR timer and performs processing to reset the MAC entity 101S in response to receiving the SCG deactivation instruction.

[0092] (1.4) Fourth Operation Example for BFD and BFR The MAC entity 101S for the SCG 201S triggers BFR in response to the detection of a beam failure by BFD. If BFD is configured to be performed when the SCG 201S is in an inactive state, the control unit 120 of the UE 100 performs processing to reset the MAC entity 101S without canceling the triggered BFR if the BFR has been triggered upon receiving an SCG deactivation instruction. By not canceling the triggered BFR, it is possible to properly perform BFR even when the SCG 201S is deactivated.

[0093] On the other hand, if the SCG 201S is not set to perform BFD when it is in an inactive state, the control unit 120 of the UE 100 cancels the triggered BFR and resets the MAC entity 101S if the BFR is triggered when the SCG deactivation instruction is received. By canceling the triggered BFR, the processing load of the UE 100 can be reduced and the occurrence of unexpected errors can be prevented.

[0094] 13 is a flow diagram showing this operation example. Here, differences from the first operation example regarding the above-mentioned BFD and BFR will be mainly explained, and overlapping explanations will be omitted.

[0095] In step S41, the control unit 120 of the UE 100 (specifically, the MAC entity 101S for the SCG 201S) triggers a BFR for the SCG 201S.

[0096] In step S42, the receiving unit 112 of the UE 100 receives an SCG deactivation instruction from, for example, the MN 200M (MCG 201M).

[0097] In step S43, the control unit 120 of the UE 100 determines whether or not it is set to perform BFD in the SCG inactive state.

[0098] If it is determined that BFD is configured to be performed in the SCG inactive state (step S43: YES), in step S44, the control unit 120 of the UE 100 performs a process to reset the MAC entity 101S without canceling the triggered BFR in response to receiving the SCG deactivation instruction.

[0099] On the other hand, if it is determined that BFD is not configured to be performed in the SCG inactive state (step S43: NO), in step S45, the control unit 120 of UE 100 cancels the triggered BFR and performs processing to reset the MAC entity 101S in response to receiving the SCG deactivation instruction.

[0100] (2) Examples of LCP operation Next, first to fourth operation examples of the UE 100 regarding the LCP according to the embodiment will be described with reference to Fig. 14 to Fig. 17. The UE 100 performs any one of the first to fourth operation examples.

[0101] In the first to fourth operation examples of the UE 100 regarding the LCP, the control unit 120 of the UE 100 (specifically, the MAC entity 101S for the SCG 201S) manages a variable Bj for each logical channel. The control unit 120 of the UE 100 performs a first process for the variable Bj when the SCG 201S is set to an inactive state, a second process while the SCG 201S is in the inactive state, and a third process when the SCG 201S is set to an active state. Here, the control unit 120 of the UE 100 performs the first to third processes so that the value of the variable Bj becomes zero when the SCG 201S is set to an active state.

[0102] (2.1) First example of LCP operation In the first operation example related to the LCP, the first process is a process of setting the value of the variable Bj to zero (i.e., initializing), the second process is a process of maintaining the value of the variable Bj, and the third process is a process of maintaining the value of the variable Bj. In this way, by initializing the value of the variable Bj when the SCG 201S is set to an inactive state and maintaining the value of the variable Bj thereafter, it is possible to set the value of the variable Bj to zero (i.e., the initial value) when the SCG 201S is switched to an active state. In particular, by maintaining the value of the variable Bj without increasing it when the SCG 201S is in an inactive state, the processing load of the UE 100 can be reduced.

[0103] FIG. 14 is a flow diagram showing this operation example.

[0104] In step S51, the control unit 120 (MAC entity 101S for SCG 201S) of the UE 100 sets a variable Bj managed by the MAC entity 101S to zero in a partial MAC reset when the SCG is deactivated.

[0105] In step S52, the control unit 120 (MAC entity 101S for SCG 201S) of the UE 100 maintains the variable Bj managed by the MAC entity 101S without increasing it while the SCG is inactive.

[0106] In step S53, the control unit 120 (MAC entity 101S for SCG 201S) of the UE 100 maintains the variable Bj managed by the MAC entity 101S without increasing it in the MAC reset at the time of SCG activation (that is, keeps the variable Bj at zero).

[0107] (2.2) Second example of LCP operation In the second operation example regarding the LCP, the first process is a process of maintaining the value of the variable Bj, the second process is a process of increasing the value of the variable Bj, and the third process is a process of setting the value of the variable Bj to zero (i.e., initializing). This makes it possible to set the value of the variable Bj to zero (i.e., the initial value) when switching the SCG201S to the active state.

[0108] FIG. 15 is a flow diagram showing this operation example.

[0109] In step S61, the control unit 120 (MAC entity 101S for SCG 201S) of the UE 100 maintains the variable Bj managed by the MAC entity 101S without initializing it in the partial MAC reset at the time of SCG deactivation.

[0110] In step S62, the control unit 120 (MAC entity 101S for SCG 201S) of the UE 100 increases the variable Bj managed by the MAC entity 101S by PBR×T while the SCG is inactive.

[0111] In step S63, the control unit 120 (MAC entity 101S for SCG 201S) of the UE 100 sets the variable Bj managed by the MAC entity 101S to zero (that is, initializes it) in a MAC reset at the time of SCG activation.

[0112] (2.3) Third example of LCP operation In the third operation example regarding the LCP, the first process is a process of setting the value of the variable Bj to zero, the second process is a process of increasing the value of the variable Bj, and the third process is a process of setting the value of the variable Bj to zero. This makes it possible to set the value of the variable Bj to zero (i.e., the initial value) when switching the SCG201S to the active state.

[0113] FIG. 16 is a flow diagram showing this operation example.

[0114] In step S71, control unit 120 (MAC entity 101S for SCG 201S) of UE 100 sets variable Bj managed by MAC entity 101S to zero (that is, initializes) in partial MAC reset when SCG is deactivated.

[0115] In step S72, the control unit 120 (MAC entity 101S for SCG 201S) of the UE 100 increases the variable Bj managed by the MAC entity 101S by PBR×T while the SCG is inactive.

[0116] In step S73, the control unit 120 (MAC entity 101S for SCG 201S) of the UE 100 sets the variable Bj managed by the MAC entity 101S to zero (that is, initializes it) in a MAC reset at the time of SCG activation.

[0117] (2.4) Fourth Example of LCP Operation In the fourth operation example related to the LCP, the first process is a process of maintaining the value of the variable Bj, the second process is a process of maintaining the value of the variable Bj, and the third process is a process of setting the value of the variable Bj to zero. This makes it possible to set the value of the variable Bj to zero (i.e., the initial value) when switching the SCG 201S to the active state. In particular, by maintaining the value of the variable Bj without increasing it when the SCG 201S is in the inactive state, the processing load of the UE 100 can be reduced.

[0118] FIG. 17 is a flow diagram showing this operation example.

[0119] In step S81, the control unit 120 (MAC entity 101S for SCG 201S) of the UE 100 maintains the variable Bj managed by the MAC entity 101S without initializing it in the partial MAC reset at the time of SCG deactivation.

[0120] In step S82, the control unit 120 (MAC entity 101S for SCG 201S) of the UE 100 maintains the variable Bj managed by the MAC entity 101S without increasing it while the SCG is inactive.

[0121] In step S83, the control unit 120 (MAC entity 101S for SCG 201S) of the UE 100 sets the variable Bj managed by the MAC entity 101S to zero (that is, initializes it) in a MAC reset at the time of SCG activation.

[0122] (3) Example of specification change Next, with reference to Figures 18 to 24, a specification change example to the technical specification "TS38.321" for the MAC layer in 5G / NR will be described as a specification change example according to the embodiment.

[0123] (3.1) Example of MAC reset specification change 18 to 20 show examples of changes to the MAC Reset specifications.

[0124] 19 and 20, in step S100, the MAC entity 101S of the UE 100 performs a partial MAC reset when a partial reset of the MAC entity 101S is requested from an upper layer. For example, the RRC layer of the UE 100 instructs the MAC entity 101S to perform a partial MAC reset in response to receiving an SCG deactivation instruction from the network 10. Alternatively, the RRC layer of the UE 100 may notify the MAC entity 101S of the receipt of the SCG deactivation instruction from the network 10, and the MAC entity 101S may initiate a partial MAC reset in response to this notification. Alternatively, the MAC entity 101S of the UE 100 may receive the SCG deactivation instruction from the SN 200S (SCG 201S) via the MAC CE, and the MAC entity 101S may initiate a partial MAC reset in response to receiving the SCG deactivation instruction.

[0125] Step S100 (partial MAC reset) may include step S101 of initializing a variable Bj managed by the MAC entity 101S for each logical channel. Specifically, the MAC entity 101S executes the process of step S101 in the case of partial MAC reset in the first and third operation examples related to the LCP described above, but does not execute the process of step S101 in the case of partial MAC reset in the second and fourth operation examples related to the LCP described above.

[0126] Step S100 (partial MAC reset) may include step S101 of initializing a variable Bj managed by the MAC entity 101S for each logical channel. Specifically, the MAC entity 101S executes the process of step S101 in the case of partial MAC reset in the first and third operation examples related to the LCP described above, but does not execute the process of step S101 in the case of partial MAC reset in the second and fourth operation examples related to the LCP described above.

[0127] Step S100 (partial MAC reset) may include step S102 of stopping all timers (currently running timers) except for the BFD timer (beamFailureDetectionTimer) and the BFR timer (beamFailureRecoveryTimer) when the RRC parameter "bfd-and-RLM" is configured. That is, when "bfd-and-RLM" is configured, the MAC entity 101S continues the timer operation without stopping the BFD timer (beamFailureDetectionTimer) and the BFR timer (beamFailureRecoveryTimer) upon SCG deactivation. On the other hand, when "bfd-and-RLM" is not configured, the MAC entity 101S stops the BFD timer (beamFailureDetectionTimer) and the BFR timer (beamFailureRecoveryTimer) upon SCG deactivation. "bfd-and-RLM" is configured in the UE 100 by an RRC message from the network 10. Also, "bfd-and-RLM" indicates that BFD and RLM (Radio Link Monitoring) are performed while the SCG is inactive.

[0128] Step S100 (partial MAC reset) may include step S103 of canceling the triggered BFR when the RRC parameter "bfd-and-RLM" is not configured. That is, when "bfd-and-RLM" is configured, the MAC entity 101S continues the BFR without canceling the triggered BFR upon SCG deactivation. On the other hand, when "bfd-and-RLM" is not configured, the MAC entity 101S cancels the triggered BFR upon SCG deactivation.

[0129] Step S100 (partial MAC reset) may include step S104 of resetting BFI counters when the RRC parameter "bfd-and-RLM" is not set. That is, when "bfd-and-RLM" is set, the MAC entity 101S continues counting operations without resetting all BFI counters managed by the MAC entity 101S upon SCG deactivation. On the other hand, when "bfd-and-RLM" is not set, the MAC entity 101S resets all BFI counters managed by the MAC entity 101S upon SCG deactivation.

[0130] (3.2) Examples of changes to BFD and BFR specifications 21 to 23 show examples of specification changes for BFD and BFR (Beam Failure Detection and Recovery procedure).

[0131] As shown in FIG. 22, BFD and BFR may include step S200 for SCG deactivation / activation.

[0132] Step S200 may include step S201 of setting a BFI counter for a serving cell belonging to an inactive SCG to zero while the SCG is inactive. Note that if the BFI counter continues counting without being reset when the SCG is deactivated, the BFI counter may be set to zero after the counting operation is completed.

[0133] Step S200 may include step S202, during SCG inactivity, of considering a Beam Failure Recovery procedure (BFR) to have been successfully completed for a serving cell belonging to an SCG in an inactive state.

[0134] (3.3) Examples of LCP specification changes FIG. 24 shows an example of a change in the LCP (Logical Channel Prioritization) specification.

[0135] As shown in Fig. 24, the LCP may include step S300 related to SCG deactivation / activation. Step S300 is a process of incrementing a variable Bj managed by the MAC entity 101S when the SCG is in an active state. On the other hand, when the SCG is in an inactive state, the variable Bj managed by the MAC entity 101S is maintained without being incremented. Such an operation corresponds to the first and fourth operation examples related to the LCP described above.

[0136] (Other embodiments) In the above-described embodiment, any of the four configurations shown in FIG. 10 may be applied as the DC configuration. As shown in FIG. 25, a configuration in which the MN 200M is an E-UTRA base station and the SN 200S is an NR base station is called (NG)EN-DC. Specifically, when the CN 30 is EPC, a configuration in which the MN 200M is an E-UTRA base station (eNB) and the SN 200S is an NR base station (en-gNB) is called EN-DC. Furthermore, when the CN 30 is 5GC, a configuration in which the MN 200M is an E-UTRA base station (ng-eNB) and the SN 200S is an NR base station (gNB) is called NGEN-DC. When the CN 30 is 5GC, a configuration in which the MN 200M is an NR base station (gNB) and the SN 200S is an E-UTRA base station (ng-eNB) is called NE-DC. Also, when CN30 is 5GC, a configuration in which MN200M is an NR base station (gNB) and SN200S is also an NR base station (gNB) is called NR-DC.

[0137] In the above embodiment, the DC in which the UE 100 communicates with two base stations (MN 200M and SN 200S) has been described, but the UE 100 may perform multiple connections with three or more base stations. Also, the UE 100 may perform multiple connections with two or more other communication devices that are not limited to base stations.

[0138] The operational sequences (and operational flows) in the above-described embodiments do not necessarily have to be executed in chronological order according to the order depicted in the flow diagrams or sequence diagrams. For example, the steps in the operations may be executed in an order different from that depicted in the flow diagrams or sequence diagrams, or may be executed in parallel. Some of the steps in the operations may be deleted, or additional steps may be added to the processing. The operational sequences (and operational flows) in the above-described embodiments may be executed independently. The operational sequences (and operational flows) in the above-described embodiments may be executed by combining two or more operational sequences (and operational flows). For example, some steps in one operational flow may be added to another operational flow, or some steps in one operational flow may be replaced with some steps in another operational flow.

[0139] In the above-described embodiment, an NR-based mobile communication system has been described as an example of the mobile communication system 1. However, the mobile communication system 1 is not limited to this example. The mobile communication system 1 may be a system conforming to the technical specifications of either LTE or another generation system (e.g., 6th generation) of the 3GPP standard. The base station 200 may be an eNB that provides E-UTRA user plane and control plane protocol termination for the UE 100 in LTE. The mobile communication system 1 may be a system conforming to a TS of a standard other than the 3GPP standard. The base station 200 may be an IAB (Integrated Access and Backhaul) donor or an IAB node. The UE 100 may be an MT in the IAB node.

[0140] A program may be provided that causes a computer to execute each process performed by the UE 100 or the base station 200. The program may be recorded in a computer-readable medium. Using the computer-readable medium, the program can be installed in 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. Furthermore, circuits that execute each process performed by the UE 100 or the base station 200 may be integrated, and at least a part of the UE 100 or the base station 200 may be configured as a semiconductor integrated circuit (chip set, SoC (System-on-a-Chip)).

[0141] In the above-described embodiments, "transmit" may mean performing processing at least one layer in a protocol stack used for transmission. Alternatively, "transmit" may mean physically transmitting a signal wirelessly or via a wired connection. Alternatively, "transmit" may mean a combination of performing processing at least one layer and physically transmitting a signal wirelessly or via a wired connection. Similarly, "receive" may mean performing processing at least one layer in a protocol stack used for reception. Alternatively, "receive" may mean physically receiving a signal wirelessly or via a wired connection. Alternatively, "receive" may mean a combination of performing processing at least one layer and physically receiving a signal wirelessly or via a wired connection. Similarly, "obtain / acquire" may mean obtaining information from stored information. Alternatively, "obtain / acquire" may mean obtaining information from information received from another node. Alternatively, "obtain / acquire" may mean obtaining information by generating the information. Similarly, "include" and "comprise" 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. Similarly, in this disclosure, "or" does not mean an exclusive or, but does mean a logical or.

[0142] Although the present disclosure has been described with reference to the embodiments, it is understood that the present disclosure is not limited to the embodiments or structures. The present disclosure also encompasses various modifications and equivalent modifications. In addition, various combinations and forms, including only one element, more than one element, or less than one element, are also within the scope and spirit of the present disclosure.

[0143] (Addendum) The following additional notes are about the features of the above-described embodiment.

[0144] (Appendix 1) A communication device (100) that communicates with a master cell group (MCG) (201M) managed by a master node (200M) and a secondary cell group (SCG) (201S) managed by a secondary node (200S), a control unit (120) having a medium access control (MAC) entity (101S) associated with the SCG (201S); The MAC entity (101S) manages, for each logical channel, a variable for allocating uplink resources to each logical channel used for communication with the SCG (201S), the variable increasing in value over time; the control unit (120) performs a first process for the variable when the SCG (201S) is in an inactive state, a second process while the SCG (201S) is in the inactive state, and a third process for the variable when the SCG (201S) is in an active state; The control unit (120) performs the first to third processes so that the value of the variable becomes zero when the SCG (201S) is put into the active state. A communication device (100).

[0145] (Appendix 2) At least some of the first to third processes are different from the other processes. 2. The communication device (100) of claim 1.

[0146] (Appendix 3) the first process is a process in a partial reset of the MAC entity (101S), The third process is a process for resetting the MAC entity (101S). 3. The communication device (100) according to claim 1 or 2.

[0147] (Appendix 4) the first process is a process of setting the value of the variable to zero, the second process is a process of maintaining the value of the variable, The third process is a process for maintaining the value of the variable. 4. A communication device (100) according to any one of claims 1 to 3.

[0148] (Appendix 5) the first process is a process of maintaining the value of the variable, the second process is a process of increasing the value of the variable, The third process is a process of setting the value of the variable to zero. 4. A communication device (100) according to any one of claims 1 to 3.

[0149] (Appendix 6) the first process is a process of setting the value of the variable to zero, the second process is a process of increasing the value of the variable, The third process is a process of setting the value of the variable to zero. 4. A communication device (100) according to any one of claims 1 to 3.

[0150] (Appendix 7) the first process is a process of maintaining the value of the variable, the second process is a process of maintaining the value of the variable, The third process is a process of setting the value of the variable to zero. 4. A communication device (100) according to any one of claims 1 to 3.

[0151] (Appendix 8) The inactive state is a state in which the communication device (100) does not transmit at least one of CSI (Channel Status Information), RACH (Random Access CHannel), SRS (Sounding Reference Signal), and UL-SCH (UL-Shared CHannel) for each serving cell belonging to the inactive SCG, and / or a state in which the communication device (100) does not monitor PDCCH (Physical Downlink Control Channel). 8. A communication device (100) according to any one of appendices 1 to 7.

[0152] (Appendix 9) A communication method for communicating with a master cell group (MCG) (201M) managed by a master node (200M) and a secondary cell group (SCG) (201S) managed by a secondary node (200S), comprising: a step in which a medium access control (MAC) entity (101S) associated with the SCG (201S) manages, for each logical channel, a variable for uplink resource allocation for each logical channel used for communication with the SCG (201S), the variable having a value that increases over time; and performing a first process on the variable when the SCG (201S) is in an inactive state, a second process while the SCG (201S) is in the inactive state, and a third process when the SCG (201S) is in an active state, The step of performing the first to third processes includes a step of performing the first to third processes so that the value of the variable becomes zero when the SCG (201S) is put into the active state. Communication method.

Claims

1. A communication device (100) that communicates with a master cell group (MCG) (201M) managed by a master node (200M) and a secondary cell group (SCG) (201S) managed by a secondary node (200S), a receiver (112) for receiving a radio resource control (RRC) message; a control unit (120) for managing variables for logical channels used in a logical channel prioritization procedure; The control unit initializing the value of the variable to zero upon establishment of the logical channel; Controlling whether to initialize the value of the variable to zero based on whether activation or deactivation of the SCG is indicated using the RRC message. Communication equipment.

2. When activation of the SCG is instructed, the value of the variable is initialized to zero. The communication device according to claim 1 .

3. When deactivation of the SCG is instructed, a reset process of the medium access control (MAC) entity is performed based on a notification of deactivation of the SCG from an RRC layer in the communication device to the MAC entity, and the value of the variable is not initialized to zero.

3. The communication device according to claim 1 or 2.

4. The MAC entity is associated with the SCG. The communication device according to claim 3 .

5. A secondary node (200S) that manages a secondary cell group (SCG) (201S) and a master node (200M) that manages a master cell group (MCG) (201M) connected to a communication device (100), a transmitter (211) for transmitting a radio resource control (RRC) message; a control unit (230) for controlling variables for logical channels used in a logical channel prioritization procedure; the value of the variable is initialized to zero upon establishment of the logical channel; Whether the value of the variable is initialized to zero is controlled based on whether activation or deactivation of the SCG is indicated using the RRC message. Master node.

6. The value of the variable is initialized to zero when activation of the SCG is instructed. The master node of claim 5 .

7. When deactivation of the SCG is instructed, a reset process of the medium access control (MAC) entity is performed based on a notification of deactivation of the SCG from an RRC layer in the communication device to the MAC entity, and the value of the variable is not initialized to zero. The master node of claim 5 .

8. The MAC entity is associated with the SCG. The master node of claim 7.

9. A communication method for a communication device (100) that communicates with a master cell group (MCG) (201M) managed by a master node (200M) and a secondary cell group (SCG) (201S) managed by a secondary node (200S), comprising: receiving a radio resource control (RRC) message; managing variables for logical channels used in a logical channel prioritization procedure; initializing the value of the variable to zero upon establishment of the logical channel; and controlling whether to initialize the value of the variable to zero based on whether activation or deactivation of the SCG is indicated using the RRC message. Communication method.

10. When activation of the SCG is instructed, the value of the variable is initialized to zero. The communication method according to claim 9.

11. When deactivation of the SCG is instructed, a reset process of the medium access control (MAC) entity is performed based on a notification of deactivation of the SCG from an RRC layer in the communication device to the MAC entity, and the value of the variable is not initialized to zero. The communication method according to claim 9.

12. The MAC entity is associated with the SCG. The communication method according to claim 11.

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