Terminal and wireless communication method

Abstract

To provide a terminal and a wireless communication method that can achieve efficient utilization of RACH resources even when a PSCell addition / change is performed in a deactivated SCG.SOLUTION: A terminal receives a message including a resetting instruction for a secondary cell group. When a secondary cell is added or changed in the state where the secondary cell group is inactive, even if the terminal performs resetting of the secondary cell based on the resetting instruction, the terminal suspends a random access procedure for a prescribed time.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present disclosure relates to a terminal and a wireless communication method that support dual connectivity. [Background technology]

[0002] The 3rd Generation Partnership Project (3GPP) has developed specifications for the 5th generation mobile communication system (5G, also known as New Radio (NR) or Next Generation (NG)), and is also developing specifications for the next generation, known as Beyond 5G, 5G Evolution, or 6G.

[0003] For example, 3GPP Release-17 is considering an extension of Multi-RAT Dual Connectivity (MR-DC) (Non-Patent Document 1). Specifically, the extension targets support for efficient activation / deactivation mechanisms for secondary cell groups (SCGs) and secondary cells (SCells).

[0004] Furthermore, with regard to supporting such an SCG activation / deactivation mechanism, several proposals have been made regarding the reconfiguration of a deactivated SCG during handover, specifically, the handling of reconfigurationWithSync (reconfiguration instruction) (see non-patent document 2). [Prior art documents] [Non-patent literature]

[0005] [Non-Patent Document 1] "Revised WID on Further Multi-RAT Dual-Connectivity enhancements", RP-201040, 3GPP TSG RAN Meeting #88e, 3GPP, June 2020 [Non-patent document 2] "Mobility and RRM for deactivated SCG", R2-2101094, 3GPP TSG-RAN WG2 meeting #113-e, 3GPP, January 2021 Summary of the Invention

[0006] The above-mentioned Non-Patent Document 2 proposes a method in which, taking into consideration that the SCG is deactivated, a terminal (User Equipment, UE) does not immediately execute a random access (RA) procedure with a Primary SCell (PSCell) even when it receives a message (specifically, an RRC Reconfiguration) from the Radio Resource Control layer (RRC).

[0007] Furthermore, when a PSCell is added or changed (PSCell addition / change), the UE also resets the settings of the medium access control layer (MAC) when it executes reconfigurationWithSync.

[0008] This may result in the UE wasting resources for the random access channel (RACH).

[0009] Therefore, the following disclosure has been made in consideration of such circumstances, and aims to provide a terminal and a wireless communication method that can realize efficient utilization of RACH resources even when a PSCell is added or changed in a deactivated SCG (deactivated SCG).

[0010] One aspect of the present disclosure is a terminal (UE200) that includes a receiving unit (RRC processing unit 220) that receives a message including a reconfiguration instruction for a secondary cell group, and a control unit (control unit 240) that, when a secondary cell is added or changed while the secondary cell group is in an inactive state, suspends a random access procedure for a specified time even if the reconfiguration of the secondary cell is performed based on the reconfiguration instruction.

[0011] One aspect of the present disclosure is a terminal (UE200) comprising: a receiving unit (RRC processing unit 220) that receives a message including a reconfiguration instruction for a secondary cell group; and a control unit (control unit 240) that, when a secondary cell is added or changed while the secondary cell group is in an inactive state, performs a random access procedure based on the reconfiguration instruction and maintains the secondary cell group in an inactive state.

[0012] One aspect of the present disclosure is a terminal (UE200) that includes a receiving unit (RRC processing unit 220) that receives a message including a reconfiguration instruction for a secondary cell group, and a control unit (control unit 240) that, when the secondary cell group is in an inactive state and a secondary cell is added or changed, performs only a portion of the reconfiguration of the secondary cell based on the reconfiguration instruction and aborts the random access procedure.

[0013] One aspect of the present disclosure is a terminal (UE200) that includes a receiving unit (RRC processing unit 220) that receives a message including a reconfiguration instruction for a secondary cell group, and a control unit (control unit 240) that, when a secondary cell is added or changed while the secondary cell group is in an inactive state, performs reconfiguration of the secondary cell based on the reconfiguration instruction after receiving the reconfiguration instruction and activation of the secondary cell group becomes necessary.

[0014] One aspect of the present disclosure is a wireless communication method including: a step of receiving, by a terminal, a message including a reconfiguration instruction for a secondary cell group; and a step of, when the secondary cell group is in an inactive state and the terminal adds or changes a secondary cell, suspending a random access procedure for a specified time even if the terminal performs reconfiguration of the secondary cell based on the reconfiguration instruction.

[0015] One aspect of the present disclosure is a wireless communication method including: a step of receiving, by a terminal, a message including a reconfiguration instruction for a secondary cell group; and a step of, when the secondary cell group is in an inactive state and the terminal adds or changes a secondary cell, performing only a part of the reconfiguration of the secondary cell based on the reconfiguration instruction and aborting a random access procedure. [Brief explanation of the drawings]

[0016] [Figure 1] FIG. 1 is a diagram showing the overall schematic configuration of a wireless communication system 10. As shown in FIG. [Figure 2] FIG. 2 is a functional block diagram of the eNB 100A. [Figure 3] FIG. 3 is a functional block diagram of the UE 200. [Figure 4] FIG. 4 is a diagram showing an example of a communication sequence regarding PSCell addition / change. [Figure 5] FIG. 5 is a diagram showing a reconfigurationWithSync-related operation flow of the UE 200 according to the first operation example. [Figure 6] FIG. 6 is a diagram showing an operation flow of the UE 200 when a trigger occurs that requires activation of the SCG. [Figure 7] FIG. 7 is a diagram showing a reconfigurationWithSync-related operation flow of the UE 200 according to the second operation example. [Figure 8] FIG. 8 is a diagram showing a reconfigurationWithSync-related operation flow of the UE 200 according to the third operation example. [Figure 9] FIG. 9 is a diagram showing a reconfigurationWithSync-related operation flow of the UE 200 according to the fourth operation example. [Figure 10] FIG. 10 is a diagram illustrating an example of the Reconfiguration with sync procedure. [Figure 11] FIG. 11 is a diagram illustrating an example of the hardware configuration of the eNB100A, the gNB100B, and the UE200. DETAILED DESCRIPTION OF THE INVENTION

[0017] Hereinafter, embodiments will be described with reference to the drawings. Note that the same or similar reference numerals are used to designate the same functions or configurations, and descriptions thereof will be omitted as appropriate.

[0018] (1) Overall configuration of the wireless communication system 1 is a schematic diagram of the overall configuration of a wireless communication system 10 according to this embodiment. The wireless communication system 10 is a wireless communication system conforming to Long Term Evolution (LTE) and 5G New Radio (NR). Note that LTE may also be called 4G, and NR may also be called 5G. The wireless communication system 10 may also be a wireless communication system conforming to a scheme called Beyond 5G, 5G Evolution, or 6G.

[0019] LTE and NR may be interpreted as radio access technologies (RATs), and in this embodiment, LTE may be referred to as the first radio access technology, and NR may be referred to as the second radio access technology.

[0020] The wireless communication system 10 includes an Evolved Universal Terrestrial Radio Access Network 20 (hereinafter, E-UTRAN 20) and a Next Generation-Radio Access Network 30 (hereinafter, NG RAN 30). The wireless communication system 10 also includes a terminal 200 (hereinafter, UE 200, User Equipment).

[0021] The E-UTRAN 20 includes an eNB 100A, which is a radio base station conforming to LTE. The NG RAN 30 includes a gNB 100B, which is a radio base station conforming to 5G (NR). Furthermore, the NG RAN 30 is connected to a User Plane Function 40 (hereinafter referred to as UPF 40), which is included in the 5G system architecture and provides user plane functions. Note that the E-UTRAN 20 and the NG RAN 30 (which may be eNB 100A or gNB 100B) may simply be referred to as a network.

[0022] The eNB100A, gNB100B and UE200 are capable of supporting carrier aggregation (CA) using multiple component carriers (CCs), and dual connectivity for simultaneously transmitting component carriers between multiple NG-RAN nodes and the UE.

[0023] The eNB100A, the gNB100B, and the UE200 perform wireless communication via a radio bearer, specifically, a Signaling Radio Bearer (SRB) or a DRB Data Radio Bearer (DRB).

[0024] In this embodiment, Multi-Radio Dual Connectivity (MR-DC) in which the eNB100A constitutes the master node (MN) and the gNB100B constitutes the secondary node (SN), specifically E-UTRA-NR Dual Connectivity (EN-DC), may be implemented, or NR-E-UTRA Dual Connectivity (NE-DC) in which the gNB100B constitutes the MN and the eNB100A constitutes the SN may be implemented, or NR-NR Dual Connectivity (NR-DC) in which the gNB constitutes both the MN and the SN may be implemented.

[0025] In this way, UE200 supports dual connectivity connecting to eNB100A and gNB100B.

[0026] The eNB 100A is included in a master cell group (MCG), and the gNB 100B is included in a secondary cell group (SCG). In other words, the gNB 100B is an SN included in the SCG.

[0027] The eNB100A and the gNB100B may also be referred to as radio base stations or network devices.

[0028] Furthermore, addition or change of a Primary SCell (PSCell) (PSCell addition / change) may be supported in the wireless communication system 10. Note that the PSCell addition / change may include conditional addition or change of a PSCell (PSCell addition / change).

[0029] A PSCell is a type of secondary cell. A PSCell means a Primary SCell (secondary cell), and may be interpreted as corresponding to any one of a plurality of SCells.

[0030] In addition, the secondary cell may be read as a secondary node (SN) or a secondary cell group (SCG).

[0031] Furthermore, a conditional inter-SN PSCell change procedure may be supported in the wireless communication system 10. Specifically, an MN-initiated conditional inter-SN PSCell change and / or an SN-initiated conditional inter-SN PSCell change may be supported.

[0032] (2) Functional block configuration of wireless communication system Next, a description will be given of the functional block configuration of the wireless communication system 10. Specifically, the functional block configurations of the eNB 100A and the UE 200 will be described.

[0033] (2.1) eNB100A Fig. 2 is a functional block diagram of the eNB 100A. As shown in Fig. 2, the eNB 100A includes a radio communication unit 110, an RRC processing unit 120, a DC processing unit 130, and a control unit 140. Note that the gNB 100B may also have similar functions to the eNB 100A, although it differs in that it supports NR.

[0034] The wireless communication unit 110 transmits downlink signals (DL signals) conforming to LTE, and also receives uplink signals (UL signals) conforming to LTE.

[0035] In addition, the wireless communication unit 110 performs assembly / disassembly of PDUs / SDUs at multiple layers (such as a medium access control layer (MAC), a radio link control layer (RLC), and a packet data convergence protocol layer (PDCP)).

[0036] The RRC processing unit 120 executes various processes in the radio resource control layer (RRC). Specifically, the RRC processing unit 120 can transmit an RRC Reconfiguration to the UE 200. Furthermore, the RRC processing unit 120 can receive an RRC Reconfiguration Complete from the UE 200, which is a response to the RRC Reconfiguration.

[0037] In this embodiment, the eNB 100A supports LTE. In this case, the name of the RRC message may be RRC Connection Reconfiguration or RRC Connection Reconfiguration Complete.

[0038] Furthermore, RRC Reconfiguration (and RRC messages between MN and SN (inter-node RRC messages)) may include reconfigurationWithSync (reconfiguration instruction) regarding cell reconfiguration. reconfigurationWithSync is specified in 3GPP TS38.331 Chapter 5.3.5.5.2, etc.

[0039] The reconfigurationWithSync may be interpreted as a common mechanism for activating a cell (NR cell) (i.e., adding an NR cell) in non-standalone (NSA) environments including other RATs (such as LTE). UE 200 can perform a random access procedure (RA procedure) based on the reconfigurationWithSync, and specific operations based on the reconfigurationWithSync will be described later.

[0040] The DC processing unit 130 performs processing related to dual connectivity, specifically, Multi-RAT Dual Connectivity (MR-DC). In this embodiment, the eNB 100A supports LTE and the gNB 100B supports NR, so the DC processing unit 130 may perform processing related to E-UTRA-NR Dual Connectivity (EN-DC). Note that, as described above, the type of DC is not limited, and may correspond to, for example, NR-E-UTRA Dual Connectivity (NE-DC) or NR-NR Dual Connectivity (NR-DC).

[0041] The DC processing unit 130 can transmit and receive messages specified in 3GPP TS37.340 and the like, and perform processing related to setting up and releasing DC between the eNB100A, the gNB100B, and the UE200.

[0042] The control unit 140 controls each functional block that configures the eNB 100 A. In particular, in this embodiment, the control unit 140 executes control related to addition or change of a secondary cell (which may be a secondary node).

[0043] Specifically, the control unit 140 can perform control related to activation / deactivation of a secondary cell group (SCG). Specifically, the control unit 140 may activate (which may also be called activation) or deactivate (which may also be called deactivation) an SCG. More specifically, the control unit 140 may activate or deactivate one or more SCells (which may include PSCells, the same applies hereinafter) included in the SCG.

[0044] An active SCG (SCell) may be interpreted as a state in which the SCG (SCell) can be immediately used by the UE 200. An inactive SCG (SCell) may be interpreted as a state in which the UE 200 cannot immediately use the SCG (SCell) but the configuration information is retained.

[0045] In this embodiment, the channels include a control channel and a data channel. The control channels include a PDCCH (Physical Downlink Control Channel), a PUCCH (Physical Uplink Control Channel), a PRACH (Physical Random Access Channel), and a PBCH (Physical Broadcast Channel).

[0046] The data channels include a physical downlink shared channel (PDSCH) and a physical uplink shared channel (PUSCH).

[0047] The reference signal includes a Demodulation Reference Signal (DMRS), a Sounding Reference Signal (SRS), a Phase Tracking Reference Signal (PTRS), and a Channel State Information-Reference Signal (CSI-RS), and the signal includes a channel and a reference signal. Furthermore, the data may refer to data transmitted via a data channel.

[0048] (2.2)UE200 3 is a functional block diagram of the UE 200. As shown in FIG. 3, the UE 200 includes a radio communication unit 210, an RRC processing unit 220, a DC processing unit 230, and a control unit 240.

[0049] The radio communication unit 210 transmits an uplink signal (UL signal) conforming to LTE or NR. The radio communication unit 210 also receives a downlink signal (DL signal) conforming to LTE or NR. That is, the UE 200 can access the eNB 100A (E-UTRAN 20) and the gNB 100B (NG RAN 30) and can support dual connectivity (specifically, EN-DC).

[0050] The radio communication unit 210, like the radio communication unit 110 of the eNB100A (gNB100B), performs assembly / disassembly of PDU / SDU in MAC, RLC, PDCP, etc.

[0051] The RRC processing unit 220 executes various processes in the radio resource control layer (RRC). Specifically, the RRC processing unit 220 can send and receive messages in the radio resource control layer.

[0052] More specifically, the RRC processing unit 220 can receive an RRC Reconfiguration transmitted from the network (the eNB 100A or the gNB 100B). The RRC processing unit 220 can also transmit an RRC Reconfiguration Complete, which is a response to the RRC Reconfiguration, to the network.

[0053] As described above, RRC Reconfiguration may include reconfigurationWithSync. reconfigurationWithSync is an information element (IE) related to cell reconfiguration, and may be broadly interpreted as a reconfiguration instruction for a cell group, specifically, an MCG or SCG. In this embodiment, the RRC processing unit 220 may configure a receiving unit that receives a message including a reconfiguration instruction for an SCG.

[0054] ReconfigurationWithSync may be defined as reconfiguration with a key change and reconfiguration without a key change. In reconfiguration with sync and key change (Type 1), at least one of the following operations may be performed:

[0055] Execute RA procedure on PSCell Reset your MAC Re-establishing RLC Re-establishing the PDCP ·SCG Security Updates In reconfiguration with sync but without key change (Type 2), at least one of the following operations may be performed:

[0056] Execute RA procedure on PSCell Reset your MAC Re-establishing RLC PDCP data recovery (for Acknowledged Mode (AM) DRB) The DC processing unit 230 performs processing related to dual connectivity, specifically, MR-DC. As described above, in this embodiment, the DC processing unit 230 may perform processing related to EN-DC, but may also support NE-DC and / or NR-DC.

[0057] The DC processing unit 230 can access each of the eNB100A and the gNB100B and perform configurations at multiple layers including RRC (such as the medium access control layer (MAC), the radio link control layer (RLC), and the packet data convergence protocol layer (PDCP)).

[0058] The control unit 240 controls each functional block constituting the UE 200. In particular, in this embodiment, the control unit 240 can execute control related to activation / deactivation (active / de-active) of a secondary cell group (SCG).

[0059] Specifically, when adding or changing a secondary cell while the SCG is inactive, the control unit 240 may operate as follows. Note that the secondary cell may be a PSCell or a normal SCell. Also, the inactive state of the SCG may be interpreted as the secondary cell (or SN) being inactive.

[0060] The control unit 240 may suspend the RA procedure for a specified time even when reconfiguration of the SCell (PSCell) is performed based on reconfigurationWithSync. Specifically, the control unit 240 may cause the RRC processing unit 220 to perform the above-described operation based on reconfigurationWithSync, but may not immediately perform the RA procedure with the target PSCell (transmit RACH), and may release the held RACH resource (dedicated RACH resource) when the specified time has elapsed.

[0061] The specified time may be the set time of timer T304 or the set time of a new timer (for convenience, referred to as T3xx). Timer T304 may be started when an RRC Reconfiguration message including reconfigurationWithSync is received or when a conditional reconfiguration is performed, that is, when a stored RRC Reconfiguration message including reconfigurationWithSync is applied, and may be stopped when random access is successfully completed in the corresponding Special Cell (SpCell).

[0062] Furthermore, the control unit 240 may perform an RA procedure based on reconfigurationWithSync and maintain the SCG in an inactive state. Specifically, the control unit 240 may cause the RRC processing unit 220 to immediately perform the above-described operation based on reconfigurationWithSync, but may maintain the SCG (which may be interpreted as a PSCell or an SCell) in an inactive state even after the operation without activating it.

[0063] Alternatively, the control unit 240 may execute only a part of the reconfiguration of the SCell (PSCell) based on reconfigurationWithSync and stop the RA procedure. Specifically, the control unit 240 may cause the RRC processing unit 220 to execute the above-mentioned operations based on reconfigurationWithSync, but may not immediately execute the RA procedure with the target PSCell (transmit RACH), and may not execute the MAC reset and operations after the MAC reset. Details of the operations executed after the MAC reset will be described later.

[0064] Alternatively, after receiving reconfigurationWithSync, if activation of an SCG becomes necessary, the control unit 240 may execute reconfiguration of the SCell (PSCell) based on reconfigurationWithSync. Specifically, even when receiving reconfigurationWithSync, the control unit 240 may not immediately cause the RRC processing unit 220 to execute the above-described operation.

[0065] When a trigger (UE activation trigger) that requires SCG activation occurs in UE200 (such as when data accumulates in a buffer inside UE200), or when an activation indication (NW activation indication) is received from the network (RRC message, MAC-CE (Control Element) or Layer 1 signaling), the control unit 240 may cause the RRC processing unit 220 to perform the above-mentioned operation based on reconfigurationWithSync.

[0066] (3) Operation of the wireless communication system Next, a description will be given of the operation of the wireless communication system 10. Specifically, a description will be given of the operation related to activation / deactivation of a secondary cell group (SCG).

[0067] (3.1) Premise 3GPP is studying support for an efficient activation / deactivation mechanism for SCG and SCell (which may include PSCell), and it has been agreed that the SCG activation state can be set at the time of PSCell addition / change, RRC resume, or handover (HO).

[0068] The inactive state (dedicated state) of the SCG may be at least one of the following states.

[0069] · PUSCH is not being transmitted in a deactivated SCG.

[0070] · PDCCH is not monitored in the PSCell of the deactivated SCG.

[0071] ·SCell dormancy is not supported for SCells in a deactivated SCG.

[0072] The UE 200 maintains the DL synchronization state.

[0073] The UE 200 performs restricted radio resource management measurements (Restricted RRM measurements).

[0074] PSCell mobility is supported.

[0075] The UE 200 performs limited radio link monitoring (RLM) and / or does not perform beam management (beam failure detection and recovery), SRS (Sounding Reference Signal) transmission, or CSI reporting.

[0076] In addition, the following proposals are being considered for operation based on reconfigurationWithSync for SCG:

[0077] (Proposal 1): Only active can be set as the target SCG activation state. UE 200 may execute reconfigurationWithSync for SCG and PSCell random access, as in the conventional case.

[0078] Option 1 is the simplest approach, where the network may explicitly deactivate the SCG after handover if necessary.

[0079] (Proposal 2): The target SCG activation state can be set to either inactive or active. UE 200 may perform PSCell random access even if the target SCG activation state is set to inactive in reconfigurationWithSync, but PSCell random access does not necessarily mean activation of the SCG.

[0080] (Proposal 3): The target SCG activation state can be set to either inactive or active. UE200 may perform PSCell random access if the target SCG activation state is set to active in the SCG-oriented reconfigurationWithSync. On the other hand, UE200 may not perform PSCell random access if the target SCG activation state is set to inactive in the SCG-oriented reconfigurationWithSync (but other actions such as SCG MAC reset may be performed). PSCell random access may be performed at a later stage (for example, at the time of SCG activation if random access is required for SCG activation).

[0081] (Proposal 4): The target SCG activation state can be set to either inactive or active. If the target SCG activation state is set to active, UE200 may perform reconfigurationWithSync for the SCG and PSCell random access. On the other hand, if the target SCG activation state is set to inactive, UE200 does not need to perform reconfigurationWithSync for the SCG.

[0082] However, reconfigurationWithSync for SCG and PSCell random access may be performed at a later stage (e.g., at the time of SCG activation). Scheme 4 is also a simple approach, and at least SCG activation may be performed using reconfigurationWithSync for SCG.

[0083] Fig. 4 shows an example of a communication sequence related to PSCell addition / change. As shown in Fig. 4, when the MN transmits RRC Reconfiguration to the UE 200 in the PSCell addition / change (addition or change of the PSCell), the RRC Reconfiguration includes an SCG RRC Reconfiguration. The SCG RRC Reconfiguration may include an information element such as reconfigurationWithSync.

[0084] The reconfigurationWithSync includes parameters of T304 and Dedicated RACH resource. The timer T304 is started when an RRC Reconfiguration message including reconfigurationWithSync is received or when a PSCell addition or change is performed, i.e., when an RRC Reconfiguration message including reconfigurationWithSync is applied, and may be stopped when random access is successfully completed in the corresponding Special Cell (SpCell).

[0085] As with 3GPP Releases 15 and 16, in PSCell addition / change, when a radio base station (e.g., gNB100B) transmits RRC Reconfiguration to UE200, UE200 must immediately perform an RA procedure with the target PSCell, i.e., transmit a RACH.

[0086] In 3GPP Release 17, the SCG activation state can be set to inactive in a PSCell addition / change. This means that UE 200 does not necessarily have to immediately perform an RA procedure with the target PSCell, i.e., transmit a RACH, but may transmit a RACH at a later stage (see Suggestions 3 and 4 above).

[0087] However, when the proposal regarding the operation based on reconfigurationWithSync for SCG as described above is also taken into consideration, the following problem exists regarding PSCell addition / change of a deactivated SCG.

[0088] (Issue 1): In 3GPP Release 15 and 16, if RACH is not completed before timer T304 expires, reconfigurationWithSync fails (t304 expiry) and the dedicated RACH resource is released. In 3GPP Release 17, if UE 200 continues to hold the dedicated RACH resource without performing RACH, the RACH resource is wasted.

[0089] (Issue 2): In 3GPP Release 15 and 16, when UE 200 operates based on reconfigurationWithSync in a PSCell addition / change, the MAC is also reset as described above. When the MAC is reset, the dedicated RACH resource is discarded. Therefore, in the above-mentioned (Proposal 3), it may become meaningless to configure the dedicated RACH resource. In other words, when the SCG is inactive, it is unclear which operation (procedure) should be executed among the series of operations based on reconfigurationWithSync.

[0090] (3.2) Example of operation Below, we will explain operation examples that can solve the above-mentioned problem 1 or problem 2. Specifically, we will explain operation examples 1 to 4. Operation examples 1 and 2 correspond to problem 1, and operation examples 3 and 4 correspond to problem 2.

[0091] Each operation example is based on the assumption that the state of the SCG (PSCell) is set to deactivated when the PSCell is added or changed.

[0092] (3.2.1) Example 1 Fig. 5 shows a reconfigurationWithSync-related operation flow of UE 200 according to operation example 1. As shown in Fig. 5, UE 200 executes a procedure based on reconfigurationWithSync (S10). Specifically, UE 200 executes an operation based on the above-described reconfigurationWithSync. In addition, upon receiving reconfigurationWithSync, timer T304 is activated (started).

[0093] However, the UE 200 may stop the RA procedure with the target PSCell, that is, the execution of RACH transmission (S20). In other words, the UE 200 does not need to immediately transmit RACH to the target PSCell even when it receives reconfigurationWithSync.

[0094] When timer T304 expires, UE 200 may release the dedicated RACH resource (S30, S40). Furthermore, UE 200 may abort the SCG failure information procedure even if timer T304 expires, i.e., even if random access has not been completed (S50). Note that only one of the processes of S40 and S50 may be executed.

[0095] The UE 200 according to the first operation example may further operate as follows: Fig. 6 shows an operation flow of the UE 200 when a trigger occurs that requires activation of the SCG.

[0096] 6, the UE 200 determines whether or not a trigger (UE activation trigger) that requires activation of the SCG has occurred in the UE 200 (S110). As described above, an example of the UE activation trigger is when data accumulates in a buffer within the UE 200, making it necessary to set up a DRB via a secondary cell.

[0097] In addition, the UE 200 determines whether an activation indication from the network (NW activation indication) has occurred (S120). Specifically, the UE 200 can receive the activation indication through an RRC message, a MAC-CE (Control Element), or Layer 1 signaling.

[0098] The UE 200 determines whether the timer T304 has expired (S130). The timer T304 can be set within a range from a minimum of 50 ms to a maximum of 10,000 ms (10 seconds).

[0099] When the timer T304 expires, the UE 200 may access the target PSCell according to a contention-based (collision-based) RA procedure (S140). That is, the UE 200 may perform contention-based RACH with the target PSCell.

[0100] On the other hand, if the timer T304 has not expired, the UE 200 may perform RACH with the target PSCell using the held dedicated RACH resource (S150).

[0101] Instead of using T304, a new timer (T3xx) may be provided. As shown in Table 1, T3xx is a timer that manages the retention of dedicated RACH resources when the state of the SCG (PSCell) is set to deactivated at the time of PSCell addition / change, and when the timer expires, the dedicated RACH resources may be discarded.

[0102] [Table 1]

[0103] The contents of ReconfigurationWihSCGDeactivated may be configured by sPcellConfigCommon, newUE-Indentity, T3xx, rach-ConfigDedicated, and smtc (SSB based RRM Measurement Timing Configuration window).

[0104] Furthermore, the timer T304 has a maximum of 10 seconds, but T3xx may be set to a larger value (for example, 1 minute). For example, T3xx may be defined as follows:

[0105] t3xx ENUMERATED {ms1000, ms2000, ms10000, ms15000, ms20000, ms25000, ms30000, ms60000},

[0106] (3.2.2) Example 2 Fig. 7 shows a reconfigurationWithSync-related operation flow of UE 200 according to operation example 2. As shown in Fig. 7, upon receiving reconfigurationWithSync, UE 200 may immediately perform an RA procedure with the target PSCell, i.e., RACH transmission (S210). Note that "immediately" may be interpreted as immediately upon receiving reconfigurationWithSync, i.e., without intentionally setting a delay using a timer or the like, but some delay that may occur in processing may be allowed.

[0107] The UE 200 executes the RA procedure with the target PSCell, but thereafter keeps the state of the SCG (PSCell) deactivated (S220), and determines whether the timer T304 has expired (S230).

[0108] When timer T304 expires, UE200 may release the dedicated RACH resource (S240). UE200 also performs an SCG failure information procedure (S250). Here, UE200 may set the failure cause to "SCGFailureWithDeactivatedState" and report the cell quality and / or beam quality of the deactivated SCG (PSCell).

[0109] Furthermore, in this operation example, UE 200 may operate as follows: Specifically, instead of maintaining the state of the SCG (PSCell) in the deactivated state (S220), UE 200 may temporarily change the state of the SCG (PSCell) to active after executing the RA procedure with the target PSCell, and then quickly (without delay) change the state to the deactivated state.

[0110] Alternatively, after executing the RA procedure with the target PSCell, the state of the SCG (PSCell) may be changed to active, but if a specific timer that was started at the time of the change expires, the state may be changed to inactive.

[0111] Furthermore, if a UE activation trigger or a NW activation indication occurs before the timeAlignmentTimer (TA timer) expires after the SCG (PSCell) state is changed to the inactive state, the UE 200 may omit RACH transmission (RA procedure) and activate the SCG (PSCell). If the timeAlignmentTimer expires, the UE 200 may access the target PSCell according to a contention-based RA procedure.

[0112] (3.2.3) Example 3 Fig. 8 shows a reconfigurationWithSync-related operation flow of UE 200 according to operation example 3. As shown in Fig. 8, UE 200 may stop the RA procedure with the target PSCell, that is, the execution of RACH transmission (S310). Specifically, UE 200 executes the operation (procedure) according to reconfigurationWithSync, but does not need to immediately transmit RACH to the target PSCell.

[0113] The UE 200 does not execute the MAC reset and the reconfigurationWithSync procedure after the MAC reset in the reconfigurationWithSync procedure (S320).

[0114] Furthermore, UE 200 may execute a part of the reconfigurationWithSync procedure (S330). Specifically, in the Reconfiguration with sync procedure specified in 3GPP TS38.331 Chapter 5.3.5.5.2, UE 200 may execute the process before "1> else: ..." immediately before the MAC reset, and may not execute the process after "1> else: ..." and after the MAC reset.

[0115] Fig. 10 shows an example of the Reconfiguration with sync procedure. As shown in Fig. 10, UE 200 may execute the process before "1> else: ..." immediately before "2> reset the MAC entity of this cell group;", and may not execute the process after "2> reset the MAC entity of this cell group;" (see underlined part).

[0116] Specifically, the UE 200 does not need to reset the MAC entity, apply the newUE-Identity as a Cell-Radio Network Temporary Identifier (C-RNTI), configure a lower layer in accordance with the received spCellConfigCommon, and so on.

[0117] Note that MAC reset may refer to resetting the MAC entity, as described above, and if a reset is requested by a higher layer, the MAC entity may discard contention-free random access resources, i.e., dedicated RACH resources.

[0118] After executing the process up to S330, if a trigger occurs that requires activation of the SCG, the UE 200 may operate according to the flow shown in Fig. 6. Also in this case, instead of reusing T304, a new timer (T3xx) may be provided.

[0119] (3.2.4) Example 4 Fig. 9 shows a reconfigurationWithSync-related operation flow of UE200 according to operation example 4. As shown in Fig. 9, UE200 may stop the reconfigurationWithSync procedure even when executing PSCell addition / change (S410). Specifically, UE200 does not need to immediately execute the reconfigurationWithSync procedure even when executing PSCell addition / change.

[0120] The UE 200 determines whether or not a trigger (UE activation trigger) that requires activation of the SCG has occurred in the UE 200 (S420). This process is similar to S110 shown in FIG.

[0121] The UE 200 also determines whether or not an activation instruction from the network (NW activation indication) has occurred (S430). This process is the same as S120 shown in FIG.

[0122] When a UE activation trigger or a NW activation indication occurs, the UE 200 may execute the aborted reconfigurationWithSync procedure (S440). Specifically, the UE 200 may execute the Reconfiguration with sync procedure specified in Chapter 5.3.5.5.2 of 3GPP TS38.331 shown in FIG. 10 .

[0123] (4) Actions and Effects According to the above-described embodiment, the following advantageous effects can be obtained. Specifically, when the UE 200 adds or changes an SCell (PSCell) while the SCG is in an inactive state, the UE 200 may suspend the RA procedure for a specified time even if it performs reconfiguration of the SCell (PSCell) based on reconfigurationWithSync. Alternatively, the UE 200 may perform the RA procedure based on reconfigurationWithSync and maintain the SCG in an inactive state.

[0124] This clarifies the RACH timing in the case of PSCell addition / change for a deactivated SCG and the timing for releasing dedicated RACH resources, making it possible to achieve both rapid SCG activation and efficient use of dedicated RACH resources.

[0125] Furthermore, in this embodiment, when the UE 200 adds or changes an SCell (PSCell) while the SCG is in an inactive state, the UE 200 may perform only a part of the reconfiguration of the SCell (PSCell) based on the reconfigurationWithSync and cancel the RA procedure. Alternatively, after receiving the reconfigurationWithSync, the UE 200 may perform the reconfiguration of the SCell (PSCell) based on the reconfigurationWithSync when activation of the SCG becomes necessary.

[0126] Therefore, when activating a deactivated SCG, the UE 200 can appropriately perform the necessary operations in the reconfigurationWithSync procedure, thereby realizing efficient operation of the UE 200, and in turn, the wireless communication system 10 as a whole.

[0127] (5) Other embodiments Although the embodiments have been described above, it will be obvious to those skilled in the art that the present invention is not limited to the description of the embodiments and that various modifications and improvements are possible.

[0128] For example, in the above-described embodiment, an EN-DC in which the MN is an eNB and the SN is a gNB has been described as an example, but as described above, other DCs may be used. Specifically, it may be an NR-DC in which the MN is a gNB and the SN is a gNB, or an NE-DC in which the MN is a gNB and the SN is an eNB.

[0129] Furthermore, SCG deactivation may be replaced with other terms having similar meanings, such as the above-mentioned deactivation and resting.

[0130] Furthermore, the block diagrams (FIGS. 2 and 3) used in the description of the above-described embodiments show functional blocks. These functional blocks (components) are realized by any combination of at least one of hardware and software. Furthermore, the method of realizing each functional block is not particularly limited. That is, each functional block may be realized using a single device that is physically or logically coupled, or may be realized using two or more physically or logically separated devices that are connected directly or indirectly (for example, by wire, wirelessly, etc.) and these multiple devices. The functional block may also be realized by combining the single device or multiple devices with software.

[0131] Functions include, but are not limited to, judgment, determination, judgment, calculation, computation, processing, derivation, investigation, search, confirmation, reception, transmission, output, access, resolution, selection, election, establishment, comparison, assumption, expectation, consideration, broadcasting, notifying, communicating, forwarding, configuring, reconfiguring, allocating, mapping, and assignment. For example, a functional block (component) that performs transmission is called a transmitting unit or transmitter. As mentioned above, there are no particular limitations on how each is implemented.

[0132] Furthermore, the above-described eNB100A, gNB100B, and UE200 (the devices) may function as a computer that performs processing of the wireless communication method of the present disclosure. Fig. 11 is a diagram showing an example of the hardware configuration of the devices. As shown in Fig. 11, the devices may be configured as a computer including a processor 1001, a memory 1002, a storage 1003, a communication device 1004, an input device 1005, an output device 1006, a bus 1007, etc.

[0133] In the following description, the term "apparatus" can be interpreted as a circuit, a device, a unit, etc. The hardware configuration of the apparatus may be configured to include one or more of the apparatuses shown in the drawings, or may be configured to exclude some of the apparatuses.

[0134] Each functional block of the device (see Figure 2.3) is realized by any hardware element of the computer device or a combination of the hardware elements.

[0135] In addition, each function of the device is realized by loading specified software (programs) onto hardware such as processor 1001 and memory 1002, causing processor 1001 to perform calculations, control communication via communication device 1004, and control at least one of reading and writing data in memory 1002 and storage 1003.

[0136] The processor 1001 controls the entire computer by running, for example, an operating system, and may be configured as a central processing unit (CPU) including an interface with peripheral devices, a control unit, an arithmetic unit, a register, and the like.

[0137] The processor 1001 also reads programs (program codes), software modules, data, etc. from at least one of the storage 1003 and the communication device 1004 into the memory 1002, and executes various processes in accordance with these. The programs used are those that cause a computer to execute at least some of the operations described in the above-mentioned embodiments. Furthermore, the various processes described above may be executed by one processor 1001, or may be executed simultaneously or sequentially by two or more processors 1001. The processor 1001 may be implemented by one or more chips. The programs may be transmitted from a network via a telecommunications line.

[0138] The memory 1002 is a computer-readable recording medium and may be configured by, for example, at least one of a read-only memory (ROM), an erasable programmable ROM (EPROM), an electrically erasable programmable ROM (EEPROM), a random access memory (RAM), etc. The memory 1002 may also be called a register, a cache, a main memory (primary storage device), etc. The memory 1002 can store a program (program code), a software module, etc., that can execute a method according to an embodiment of the present disclosure.

[0139] Storage 1003 is a computer-readable recording medium, and may be, for example, at least one of an optical disk such as a Compact Disc ROM (CD-ROM), a hard disk drive, a flexible disk, a magneto-optical disk (e.g., a compact disk, a digital versatile disk, a Blu-ray disc), a smart card, a flash memory (e.g., a card, a stick, a key drive), a floppy disk, a magnetic strip, etc. Storage 1003 may also be referred to as an auxiliary storage device. The above-mentioned recording medium may be, for example, a database, a server, or other appropriate medium including at least one of memory 1002 and storage 1003.

[0140] The communication device 1004 is hardware (transmission / reception device) for communicating between computers via at least one of a wired network and a wireless network, and is also called, for example, a network device, a network controller, a network card, or a communication module.

[0141] The communication device 1004 may be configured to include a high-frequency switch, a duplexer, a filter, a frequency synthesizer, etc. to realize, for example, at least one of Frequency Division Duplex (FDD) and Time Division Duplex (TDD).

[0142] The input device 1005 is an input device (for example, a keyboard, a mouse, a microphone, a switch, a button, a sensor, etc.) that receives input from the outside. The output device 1006 is an output device (for example, a display, a speaker, an LED lamp, etc.) that outputs to the outside. The input device 1005 and the output device 1006 may be integrated into one device (for example, a touch panel).

[0143] Furthermore, each device such as the processor 1001 and the memory 1002 is connected to a bus 1007 for communicating information. The bus 1007 may be configured using a single bus, or may be configured using different buses between each device.

[0144] Furthermore, the device may be configured to include hardware such as a microprocessor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a programmable logic device (PLD), or a field programmable gate array (FPGA), and some or all of the functional blocks may be realized by the hardware. For example, the processor 1001 may be implemented using at least one of these pieces of hardware.

[0145] Furthermore, the notification of information is not limited to the aspects / embodiments described in the present disclosure, and may be performed using other methods. For example, the notification of information may be performed by physical layer signaling (e.g., Downlink Control Information (DCI), Uplink Control Information (UCI)), higher layer signaling (e.g., RRC signaling, Medium Access Control (MAC) signaling, broadcast information (Master Information Block (MIB), System Information Block (SIB))), other signals, or a combination thereof. Furthermore, the RRC signaling may be referred to as an RRC message, and may be, for example, an RRC Connection Setup message, an RRC Connection Reconfiguration message, or the like.

[0146] Each aspect / embodiment described in the present disclosure may be applied to at least one of a system using Long Term Evolution (LTE), LTE-Advanced (LTE-A), SUPER 3G, IMT-Advanced, a 4th generation mobile communication system (4G), a 5th generation mobile communication system (5G), Future Radio Access (FRA), New Radio (NR), W-CDMA (registered trademark), GSM (registered trademark), CDMA2000, Ultra Mobile Broadband (UMB), IEEE 802.11 (Wi-Fi (registered trademark)), IEEE 802.16 (WiMAX (registered trademark)), IEEE 802.20, Ultra-WideBand (UWB), Bluetooth (registered trademark), or other suitable system, and a next-generation system extended based on these. Furthermore, a combination of multiple systems (e.g., a combination of at least one of LTE and LTE-A and 5G) may also be applied.

[0147] The order of the procedures, sequences, flowcharts, etc. of each aspect / embodiment described in this disclosure may be changed unless it is consistent. For example, the methods described in this disclosure present elements of various steps using an example order, and are not limited to the particular order presented.

[0148] In the present disclosure, a specific operation described as being performed by a base station may also be performed by its upper node in some cases. In a network consisting of one or more network nodes having a base station, it is clear that various operations performed for communication with a terminal may be performed by at least one of the base station and another network node other than the base station (for example, an MME or an S-GW, etc., but are not limited to these). Although the above example illustrates a case where there is one other network node other than the base station, a combination of multiple other network nodes (for example, an MME and an S-GW) may also be used.

[0149] Information, signals (information, etc.) may be output from a higher layer (or a lower layer) to a lower layer (or a higher layer), or may be input / output via multiple network nodes.

[0150] Input and output information may be stored in a specific location (for example, memory) or may be managed using a management table. Input and output information may be overwritten, updated, or added to. Output information may be deleted. Input information may be sent to another device.

[0151] The determination may be made based on a value represented by one bit (0 or 1), a Boolean value (true or false), or a numerical comparison (e.g., comparison with a predetermined value).

[0152] Each aspect / embodiment described in this disclosure may be used alone, in combination, or switched depending on the implementation. Furthermore, notification of predetermined information (e.g., notification that "X is true") is not limited to being done explicitly, but may be done implicitly (e.g., by not notifying the predetermined information).

[0153] Software shall be construed broadly to mean instructions, instruction sets, code, code segments, program code, programs, subprograms, software modules, applications, software applications, software packages, routines, subroutines, objects, executable files, threads of execution, procedures, functions, etc., whether referred to as software, firmware, middleware, microcode, hardware description language, or otherwise.

[0154] Software, instructions, information, etc. may also be transmitted or received over a transmission medium. For example, if software is transmitted from a website, server, or other remote source using wired technologies (such as coaxial cable, fiber optic cable, twisted pair, Digital Subscriber Line (DSL)), and / or wireless technologies (such as infrared, microwave), then these wired and / or wireless technologies are included within the definition of transmission media.

[0155] The information, signals, etc. described in this disclosure may be represented using any of a variety of different technologies. For example, data, instructions, commands, information, signals, bits, symbols, chips, etc. that may be referred to throughout the above description may be represented by voltages, currents, electromagnetic waves, magnetic fields or magnetic particles, optical fields or photons, or any combination thereof.

[0156] Note that terms explained in this disclosure and terms necessary for understanding this disclosure may be replaced with terms having the same or similar meanings. For example, at least one of a channel and a symbol may be a signal (signaling). Furthermore, a signal may be a message. Furthermore, a component carrier (CC) may be called a carrier frequency, a cell, a frequency carrier, etc.

[0157] As used in this disclosure, the terms "system" and "network" are used interchangeably.

[0158] Furthermore, the information, parameters, etc. described in the present disclosure may be expressed using absolute values, may be expressed using relative values from a predetermined value, or may be expressed using other corresponding information. For example, a radio resource may be indicated by an index.

[0159] The names used for the above-described parameters are not intended to be limiting in any way. Furthermore, the mathematical expressions using these parameters may differ from those explicitly disclosed in this disclosure. The various channels (e.g., PUCCH, PDCCH, etc.) and information elements may be identified by any suitable names, and therefore the various names assigned to these various channels and information elements are not intended to be limiting in any way.

[0160] In this disclosure, terms such as "base station (BS)," "radio base station," "fixed station," "NodeB," "eNodeB (eNB)," "gNodeB (gNB)," "access point," "transmission point," "reception point," "transmission / reception point," "cell," "sector," "cell group," "carrier," and "component carrier" may be used interchangeably. Base stations may also be referred to by terms such as macrocell, small cell, femtocell, and picocell.

[0161] A base station can accommodate one or more (e.g., three) cells (also called sectors). When a base station accommodates multiple cells, the overall coverage area of the base station can be divided into multiple smaller areas, and each smaller area can be provided with communication services by a base station subsystem (e.g., a small indoor base station (Remote Radio Head: RRH)).

[0162] The terms "cell" or "sector" refer to part or all of the coverage area of a base station and / or base station subsystem that provides communication services within that coverage area.

[0163] In this disclosure, the terms "Mobile Station (MS)," "user terminal," "User Equipment (UE)," "terminal," etc. may be used interchangeably.

[0164] A mobile station may also be referred to by those skilled in the art as a subscriber station, mobile unit, subscriber unit, wireless unit, remote unit, mobile device, wireless device, wireless communication device, remote device, mobile subscriber station, access terminal, mobile terminal, wireless terminal, remote terminal, handset, user agent, mobile client, client, or some other suitable terminology.

[0165] At least one of the base station and the mobile station may be called a transmitting device, a receiving device, a communication device, etc. At least one of the base station and the mobile station may be a device mounted on a mobile object, or the mobile object itself. The mobile object may be a vehicle (e.g., a car, an airplane, etc.), an unmanned mobile object (e.g., a drone, an autonomous vehicle, etc.), or a robot (manned or unmanned). At least one of the base station and the mobile station may also include devices that do not necessarily move during communication operations. For example, at least one of the base station and the mobile station may be an Internet of Things (IoT) device such as a sensor.

[0166] Furthermore, a base station in the present disclosure may be read as a mobile station (user terminal, the same applies hereinafter). For example, the aspects / embodiments of the present disclosure may be applied to a configuration in which communication between a base station and a mobile station is replaced with communication between multiple mobile stations (which may be called, for example, Device-to-Device (D2D) or Vehicle-to-Everything (V2X)). In this case, the mobile station may be configured to have the functions of a base station. Furthermore, terms such as "uplink" and "downlink" may be read as terms corresponding to communication between terminals (for example, "side"). For example, terms such as uplink channel and downlink channel may be read as side channel.

[0167] Similarly, a mobile station in the present disclosure may be interpreted as a base station, in which case the base station may have the functions of a mobile station. A radio frame may be composed of one or more frames in the time domain. Each of the one or more frames in the time domain may be called a subframe. A subframe may further be composed of one or more slots in the time domain. A subframe may have a fixed time length (e.g., 1 ms) that is independent of numerology.

[0168] Numerology may be a communication parameter applied to at least one of transmission and reception of a signal or channel, such as subcarrier spacing (SCS), bandwidth, symbol length, cyclic prefix length, transmission time interval (TTI), number of symbols per TTI, radio frame structure, specific filtering operations performed by a transceiver in the frequency domain, and specific windowing operations performed by a transceiver in the time domain.

[0169] A slot may consist of one or more symbols in the time domain (such as an Orthogonal Frequency Division Multiplexing (OFDM) symbol, a Single Carrier Frequency Division Multiple Access (SC-FDMA) symbol, etc.) A slot may be a numerology-based time unit.

[0170] A slot may include multiple minislots. Each minislot may consist of one or more symbols in the time domain. A minislot may also be called a subslot. A minislot may consist of fewer symbols than a slot. A PDSCH (or PUSCH) transmitted in a time unit larger than a minislot may be called PDSCH (or PUSCH) mapping type A. A PDSCH (or PUSCH) transmitted using a minislot may be called PDSCH (or PUSCH) mapping type B.

[0171] The radio frame, subframe, slot, minislot, and symbol all represent time units for transmitting signals, and may be referred to by other names corresponding to the radio frame, subframe, slot, minislot, and symbol.

[0172] For example, one subframe may be called a transmission time interval (TTI), multiple consecutive subframes may be called a TTI, or one slot or one minislot may be called a TTI. That is, at least one of the subframe and the TTI may be a subframe (1 ms) in existing LTE, a period shorter than 1 ms (e.g., 1-13 symbols), or a period longer than 1 ms. Note that the unit representing the TTI may be called a slot, minislot, etc., instead of a subframe.

[0173] Here, TTI refers to, for example, the smallest time unit for scheduling in wireless communication. For example, in an LTE system, a base station performs scheduling to allocate radio resources (such as frequency bandwidth and transmission power that can be used by each user terminal) to each user terminal in TTI units. However, the definition of TTI is not limited to this.

[0174] The TTI may be a transmission time unit for a channel-encoded data packet (transport block), a code block, a code word, etc., or may be a processing unit for scheduling, link adaptation, etc. When a TTI is given, the time interval (e.g., the number of symbols) to which a transport block, a code block, a code word, etc. is actually mapped may be shorter than the TTI.

[0175] When one slot or one minislot is called a TTI, one or more TTIs (i.e., one or more slots or one or more minislots) may be the minimum time unit for scheduling. Also, the number of slots (minislots) constituting the minimum time unit for scheduling may be controlled.

[0176] A TTI having a time length of 1 ms may be called a regular TTI (TTI in LTE Rel. 8-12), normal TTI, long TTI, regular subframe, normal subframe, long subframe, slot, etc. A TTI shorter than a regular TTI may be called a shortened TTI, short TTI, partial or fractional TTI, shortened subframe, short subframe, minislot, subslot, slot, etc.

[0177] In addition, a long TTI (e.g., a normal TTI, a subframe, etc.) may be interpreted as a TTI having a time length of more than 1 ms, and a short TTI (e.g., a shortened TTI, etc.) may be interpreted as a TTI having a TTI length shorter than the TTI length of a long TTI and equal to or greater than 1 ms.

[0178] A resource block (RB) is a resource allocation unit in the time domain and frequency domain, and may include one or more consecutive subcarriers in the frequency domain. The number of subcarriers included in an RB may be the same regardless of numerology, for example, 12. The number of subcarriers included in an RB may also be determined based on numerology.

[0179] The time domain of an RB may include one or more symbols and may be one slot, one minislot, one subframe, or one TTI in length. Each TTI, subframe, etc. may be composed of one or more resource blocks.

[0180] Note that one or more RBs may also be called a physical resource block (PRB), a sub-carrier group (SCG), a resource element group (REG), a PRB pair, an RB pair, or the like.

[0181] Furthermore, a resource block may be composed of one or more resource elements (REs). For example, one RE may be a radio resource region of one subcarrier and one symbol.

[0182] A Bandwidth Part (BWP) (which may also be referred to as a fractional bandwidth) may represent a subset of contiguous common resource blocks (RBs) for a given numerology on a given carrier, where the common RBs may be identified by their index relative to a common reference point of the carrier. PRBs may be defined in a given BWP and numbered within that BWP.

[0183] The BWP may include a BWP for UL (UL BWP) and a BWP for DL (DL BWP). One or more BWPs may be configured for a UE within one carrier.

[0184] At least one of the configured BWPs may be active, and the UE may not expect to transmit or receive a given signal / channel outside the active BWP. Note that the terms "cell," "carrier," etc. in this disclosure may be read as "BWP."

[0185] The above-described structures of the radio frame, subframe, slot, minislot, and symbol are merely examples. For example, the number of subframes included in a radio frame, the number of slots per subframe or radio frame, the number of minislots included in a slot, the number of symbols and RBs included in a slot or minislot, the number of subcarriers included in an RB, the number of symbols in a TTI, the symbol length, the cyclic prefix (CP) length, and other configurations can be changed in various ways.

[0186] The terms "connected," "coupled," or any variation thereof, refer to any direct or indirect connection or coupling between two or more elements, and may include the presence of one or more intermediate elements between two elements that are "connected" or "coupled" to each other. The coupling or connection between elements may be physical, logical, or a combination thereof. For example, "connected" may be read as "access." As used in this disclosure, two elements may be considered to be "connected" or "coupled" to each other using one or more wires, cables, and / or printed electrical connections, as well as electromagnetic energy having wavelengths in the radio frequency range, microwave range, and optical (both visible and invisible) range, as some non-limiting and non-exhaustive examples.

[0187] The reference signal may also be abbreviated as Reference Signal (RS), and may also be called a pilot depending on the applicable standard.

[0188] As used in this disclosure, the phrase "based on" does not mean "based only on," unless expressly stated otherwise. In other words, the phrase "based on" means both "based only on" and "based at least on."

[0189] The "means" in the configuration of each of the above devices may be replaced with "part," "circuit," "device," etc.

[0190] As used in this disclosure, any reference to an element using a designation such as "first," "second," etc. does not generally limit the quantity or order of those elements. These designations may be used in this disclosure 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.

[0191] When used in this disclosure, the terms "include," "including," and variations thereof are intended to be inclusive, similar to the term "comprising." Furthermore, when used in this disclosure, the term "or" is not intended to be an exclusive or.

[0192] In this disclosure, where articles are added by translation, such as a, an, and the in English, the disclosure may include that the nouns following these articles are in the plural form.

[0193] As used in this disclosure, the terms "determining" and "determining" may encompass a wide variety of actions. "Determining" and "determining" may include, for example, judging, calculating, computing, processing, deriving, investigating, looking up, searching, inquiring (e.g., searching in a table, database, or other data structure), ascertaining, and the like. "Determining" and "determining" may also include receiving (e.g., receiving information), transmitting (e.g., sending information), input, output, accessing (e.g., accessing data in memory), and the like. Furthermore, "judgment" and "decision" can include regarding resolving, selecting, choosing, establishing, comparing, etc. as having been "judged" or "decided." In other words, "judgment" and "decision" can include regarding some action as having been "judged" or "decided." Furthermore, "judgment (decision)" can be interpreted as "assuming," "expecting," "considering," etc.

[0194] In the present disclosure, the term "A and B are different" may mean "A and B are different from each other." The term may also mean "A and B are each different from C." Terms such as "separate" and "coupled" may also be interpreted in the same way as "different."

[0195] Although the present disclosure has been described in detail above, it is clear to those skilled in the art that the present disclosure is not limited to the embodiments described herein. The present disclosure can be implemented in modified and altered forms without departing from the spirit and scope of the present disclosure as defined by the claims. Therefore, the description of the present disclosure is intended to be illustrative and does not have any limiting meaning on the present disclosure. [Explanation of symbols]

[0196] 10. Wireless communication systems 20 E-UTRAN 30 NG RAN 40 UPF 100A eNB 100B gNB 110 Radio Communication Department 120 RRC processing unit 130 DC processing section 140 Control Unit 200 UE 210 Radio Communication Department 220 RRC processing unit 230 DC processing section 240 Control Unit 1001 processor 1002 memory 1003 Storage 1004 Communication equipment 1005 Input Device 1006 Output Device 1007 Bus

Claims

1. A receiving unit that receives a message including a secondary cell group reconfiguration instruction; a control unit that determines, based on a predetermined timer, whether or not random access is required to activate the secondary cell group when a secondary cell is added or changed while the secondary cell group is in an inactive state; A terminal comprising:

2. The control unit activates the secondary cell group without performing random access if the timer has not yet expired, and activates the secondary cell group by performing random access if the timer has expired. The terminal according to claim 1.

3. receiving a message including a secondary cell group reconfiguration instruction; When the secondary cell group is in an inactive state and a secondary cell is added or changed, determining whether or not random access is required to activate the secondary cell group based on a predetermined timer. The communication method of the device.

4. In a communication system including a base station and a terminal, The terminal a receiving unit that receives a message including a secondary cell group reconfiguration instruction from the base station; A control unit that determines whether or not random access is required to activate the secondary cell group based on a predetermined timer when a secondary cell is added or changed while the secondary cell group is in an inactive state. Communication system.

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