User equipment, base station, and communication system

Abstract

To provide a low-latency, high-reliability wireless communication technology in NR.SOLUTION: A low-latency, highly reliable communication system, etc. is provides. Even after transitioning from RRC_CONNECTED to RRC_INACTIVE (ST801), a communication terminal device maintains secondary base station configuration information regarding a secondary base station configuration (ST803). Even when at least one of a master base station and a secondary base station is changed during RRC_INACTIVE (ST802), the communication terminal device maintains secondary base station configuration information (ST803). The communication terminal device transitions to RRC_CONNECTED again using the maintained secondary base station configuration information.SELECTED DRAWING: Figure 29

Description

Technical Field

[0001] The present invention relates to wireless communication technology.

Background Art

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

[0049] In the frame structure of NR, various subcarrier intervals, that is, various numerologies are supported. In NR, regardless of the numerology, one subframe is 1 millisecond, and one slot is composed of 14 symbols. Also, the number of slots included in one subframe is one in the numerology with a subcarrier interval of 15 kHz, and in other numerologies, it increases in proportion to the subcarrier interval (see Non-Patent Document 13 (TS38.211 v15.0.0)).

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

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

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

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

[0054] In 3GPP, as forms of DC, DC by an LTE base station connected to the EPC and an NR base station, DC by an NR base station connected to a 5G core system, and DC by an LTE base station and an NR base station connected to a 5G core system are being studied (see Non-Patent Documents 12, 16, and 24).

[0055] Also, in 3GPP, several new technologies are being studied. For example, a rapid return to RRC_CONNECTED by maintaining the SDAP / PDCP settings during RRC_INACTIVE, ensuring UL coverage by using SUL (Supplementary Uplink), etc. are being studied (see Non-Patent Documents 16, 17, and 20).

[0056] In NR, the SRS used for sounding the uplink channel is allocated within the range of the last 6 symbols of 1 slot composed of 14 symbols. Also, the number of symbols of the SRS is either 1, 2, or 4 (see Non-Patent Documents 13 and 15).

Prior Art Documents

Non-Patent Documents

[0057]

Non-Patent Document 1

Non-Patent Document 2

Non-Patent Document 3

Non-Patent Document 20

Non-Patent Document 21

Non-Patent Document 22

Non-Patent Document 23

Non-Patent Document 24

Summary of the Invention

Problems to be Solved by the Invention

[0058] When a UE using a DC configuration in which a higher-level NW device becomes a 5G core (hereinafter sometimes referred to as 5GC) transitions to RRC_INACTIVE, the settings of the secondary base station are released. For this reason, when the UE returns from RRC_INACTIVE to RRC_CONNECTED, the base station needs to reconfigure the secondary base station for the UE. As a result, it takes time to restore the DC configuration, and a delay occurs when the DC configuration is restored.

[0059] Also, in NR, in order to compensate for the difference in the UL coverage of NR, an uplink using a low frequency, that is, SUL (Supplementary UpLink; see Section 5.16 of Non-Patent Document 17) is used. However, there is no disclosure regarding the switching method between SUL and non-SUL in Configured Grant (see Section 10.3 of Non-Patent Document 16) or preemption. As a result, in Configured Grant or preemption, an appropriate selection between SUL and non-SUL becomes impossible, and as a result, for example, the reliability of the uplink at the cell edge decreases.

[0060] In view of the above problems, one object of the present invention is to provide a low-latency and high-reliability wireless communication technology in NR.

Means for Solving the Problem

[0061] According to the present disclosure, for example, there is provided a user equipment in a communication system including a user equipment and a base station that wirelessly communicates with the user equipment, wherein the user equipment notifies the base station of capability information including information regarding a switching time between a plurality of uplink carriers.

[0062] Also, according to the present disclosure, for example, there is provided a base station in a communication system including a user equipment and a base station that wirelessly communicates with the user equipment, wherein the base station receives, from the user equipment, capability information including information regarding a switching time between a plurality of uplink carriers. Also, according to the present disclosure, for example, there is provided a communication system including a user equipment and a base station that wirelessly communicates with the user equipment, wherein the user equipment notifies the base station of capability information including information regarding a switching time between a plurality of uplink carriers.

Advantages of the Invention

[0063] According to the user equipment and the like of the present disclosure, it is possible to obtain high reliability.

[0064] The objects, features, aspects, and advantages of the present invention will become more apparent from the following detailed description and the accompanying drawings.

Brief Description of the Drawings

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Mode for Carrying Out the Invention

[0066] Embodiment 1. FIG. 2 is a block diagram showing the overall configuration of a communication system 200 of the LTE system being discussed in 3GPP. FIG. 2 will be described. The radio access network is referred to as E-UTRAN (Evolved Universal Terrestrial Radio Access Network) 201. A mobile terminal device (hereinafter simply referred to as "mobile terminal (User Equipment: UE)") 202, which is a communication terminal device, can communicate wirelessly with a base station device (hereinafter referred to as "base station (E-UTRAN NodeB: eNB)") 203 and performs signal transmission and reception through wireless communication.

[0067] Here, the "communication terminal device" includes not only mobile terminal devices such as mobile phone terminal devices that can move, but also non-mobile devices such as sensors. In the following description, the "communication terminal device" may sometimes be simply referred to as the "communication terminal".

[0068] If the control protocol for the mobile terminal 202, for example, RRC (Radio Resource Control), and the user plane (hereinafter sometimes referred to as U-Plane), for example, PDCP (Packet Data Convergence Protocol), RLC (Radio Link Control), MAC (Medium Access Control), PHY (Physical layer) terminate at the base station 203, the E-UTRAN is composed of one or more base stations 203.

[0069] The control protocol RRC (Radio Resource Control) between the mobile terminal 202 and the base station 203 performs functions such as broadcast, paging, and RRC connection management. As the states of the base station 203 and the mobile terminal 202 in RRC, there are RRC_IDLE and RRC_CONNECTED.

[0070] In RRC_IDLE, PLMN (Public Land Mobile Network) selection, System Information (SI) notification, paging, cell re-selection, mobility, etc. are performed. In RRC_CONNECTED, the mobile terminal has an RRC connection and can transmit and receive data with the network. Also in RRC_CONNECTED, handover (HO), measurement of neighbouring cells, etc. are performed.

[0071] The base station 203 is composed of one or more eNBs 207. Also, a system composed of the EPC (Evolved Packet Core) which is the core network and the E-UTRAN 201 which is the radio access network is called EPS (Evolved Packet System). Sometimes, the combination of the EPC which is the core network and the E-UTRAN 201 which is the radio access network is referred to as the "network".

[0072] The eNB 207 is connected to the Mobility Management Entity (MME), or the Serving Gateway (S-GW), or an MME / S-GW unit (hereinafter sometimes referred to as the "MME unit") 204 that includes the MME and the S-GW via the S1 interface, and control information is communicated between the eNB 207 and the MME unit 204. A plurality of MME units 204 may be connected to one eNB 207. The eNBs 207 are connected via the X2 interface, and control information is communicated between the eNBs 207.

[0073] The MME unit 204 is a higher-level device, specifically a higher-level node, and controls the connection between the eNB 207 which is a base station and the user equipment (UE) 202. The MME unit 204 constitutes the EPC which is the core network. The base station 203 constitutes the E-UTRAN 201.

[0074] The base station 203 may constitute one cell or a plurality of cells. Each cell has a range predetermined as coverage, which is a range within which communication with the mobile terminal 202 is possible, and wireless communication is performed with the mobile terminal 202 within the coverage. When one base station 203 constitutes a plurality of cells, each cell is configured to enable communication with the mobile terminal 202.

[0075] Figure 3 is a block diagram showing the overall configuration of a 5G communication system 210 discussed in 3GPP. Figure 3 will be described. The radio access network is referred to as NG-RAN (Next Generation Radio Access Network) 211. The UE 202 can communicate wirelessly with an NR base station device (hereinafter referred to as "NR base station (NG-RAN NodeB: gNB)") 213 and transmits and receives signals through wireless communication. Also, the core network is referred to as 5G Core (5GC).

[0076] If the control protocol for the UE 212, for example, RRC (Radio Resource Control), and the user plane (hereinafter sometimes referred to as U-Plane), for example, SDAP (Service Data Adaptation Protocol), PDCP (Packet Data Convergence Protocol), RLC (Radio Link Control), MAC (Medium Access Control), PHY (Physical layer), terminate at the NR base station 213, the NG-RAN is composed of one or a plurality of NR base stations 213.

[0077] The function of the control protocol RRC (Radio Resource Control) between the UE 202 and the NR base station 213 is the same as that of LTE. As the states of the NR base station 213 and the UE 202 in RRC, there are RRC_IDLE, RRC_CONNECTED, and RRC_INACTIVE.

[0078] RRC_IDLE and RRC_CONNECTED are the same as in the LTE mode. While maintaining the connection between the 5G core network and the NR base station 213, RRC_INACTIVE performs system information (SI) notification, paging, cell re-selection, mobility, etc.

[0079] The gNB 217 is connected to the Access and Mobility Management Function (AMF), Session Management Function (SMF), or User Plane Function (UPF), or an AMF / SMF / UPF unit (hereinafter sometimes referred to as the "5GC unit") 214 including the AMF, SMF, and UPF, via the NG interface. Control information and / or user data are communicated between the gNB 217 and the 5GC unit 214. The NG interface is a general term for the N2 interface between the gNB 217 and the AMF, the N3 interface between the gNB 217 and the UPF, the N11 interface between the AMF and the SMF, and the N4 interface between the UPF and the SMF. For one gNB 217, a plurality of 5GC units 204 may be connected. The gNBs 217 are connected via the Xn interface, and control information and / or user data are communicated between the gNBs 217.

[0080] Similar to the base station 203, the NR base station 213 may also consist of one or more cells. When one NR base station 213 consists of a plurality of cells, each cell is configured to be able to communicate with the UE 212.

[0081] gNB 217 may be divided into a Central Unit (hereinafter sometimes referred to as CU) 218 and a Distributed Unit (hereinafter sometimes referred to as DU) 219. One CU 218 is configured within gNB 217. One or more DUs 219 are configured within gNB 217. The CU 218 is connected to the DU 219 via an F1 interface, and control information and / or user data are communicated between the CU 218 and the DU 219.

[0082] FIG. 4 is a diagram showing the configuration of DC by an eNB and a gNB connected to the EPC. In FIG. 4, solid lines indicate U-Plane connections, and dashed lines indicate C-Plane connections. In FIG. 4, eNB 223-1 serves as the master base station, and gNB 224-2 serves as the secondary base station (this DC configuration may sometimes be referred to as EN-DC). In FIG. 4, an example is shown in which the U-Plane connection between the MME unit 204 and gNB 224-2 is made via eNB 223-1, but it may also be made directly between the MME unit 221 and gNB 224-2.

[0083] FIG. 5 is a diagram showing the configuration of DC by a gNB connected to the NG core. In FIG. 5, solid lines indicate U-Plane connections, and dashed lines indicate C-Plane connections. In FIG. 5, gNB 224-1 serves as the master base station, and gNB 224-2 serves as the secondary base station (this DC configuration may sometimes be referred to as NR-DC). In FIG. 5, an example is shown in which the U-Plane connection between the 5GC unit 214 and gNB 224-2 is made via gNB 224-1, but it may also be made directly between the 5GC unit 214 and gNB 224-2.

[0084] FIG. 6 is a diagram showing the configuration of DC by eNB and gNB connected to the NG core. In FIG. 6, solid lines indicate U-Plane connections, and dashed lines indicate C-Plane connections. In FIG. 6, eNB226-1 becomes the master base station, and gNB224-2 becomes the secondary base station (this DC configuration may be referred to as NG-EN-DC). In FIG. 6, an example is shown in which the U-Plane connection between the 5GC unit 214 and gNB224-2 is made via eNB226-1, but it may also be made directly between the 5GC unit 214 and gNB224-2.

[0085] FIG. 7 is a diagram showing another configuration of DC by eNB and gNB connected to the NG core. In FIG. 7, solid lines indicate U-Plane connections, and dashed lines indicate C-Plane connections. In FIG. 7, gNB224-1 becomes the master base station, and eNB226-2 becomes the secondary base station (this DC configuration may be referred to as NE-DC). In FIG. 7, an example is shown in which the U-Plane connection between the 5GC unit 214 and eNB226-2 is made via gNB224-1, but it may also be made directly between the 5GC unit 214 and eNB226-2.

[0086] FIG. 8 is a block diagram showing the configuration of the mobile terminal 202 shown in FIG. 2. The transmission process of the mobile terminal 202 shown in FIG. 8 will be described. First, the control data from the protocol processing unit 301 and the user data from the application unit 302 are stored in the transmission data buffer unit 303. The data stored in the transmission data buffer unit 303 is passed to the encoder unit 304, and encoding processes such as error correction are performed. There may be data that is directly output from the transmission data buffer unit 303 to the modulation unit 305 without undergoing the encoding process. The data encoded by the encoder unit 304 is subjected to modulation processing in the modulation unit 305. In the modulation unit 305, precoding in MIMO may be performed. The modulated data is converted into a baseband signal and then output to the frequency conversion unit 306, where it is converted to a wireless transmission frequency. Thereafter, transmission signals are transmitted from the antennas 307-1 to 307-4 to the base station 203. In FIG. 8, the case where the number of antennas is four is illustrated, but the number of antennas is not limited to four.

[0087] Also, the reception process of the mobile terminal 202 is executed as follows. The wireless signal from the base station 203 is received by the antennas 307-1 to 307-4. The received signal is converted from the wireless reception frequency to a baseband signal by the frequency conversion unit 306, and demodulation processing is performed in the demodulation unit 308. In the demodulation unit 308, weight calculation and multiplication processing may be performed. The demodulated data is passed to the decoder unit 309, and decoding processes such as error correction are performed. Among the decoded data, the control data is passed to the protocol processing unit 301, and the user data is passed to the application unit 302. A series of processes of the mobile terminal 202 are controlled by the control unit 310. Therefore, although omitted in FIG. 8, the control unit 310 is connected to each of the units 301 to 309. In FIG. 8, the number of antennas used for transmission by the mobile terminal 202 and the number of antennas used for reception may be the same or different.

[0088] FIG. 9 is a block diagram showing the configuration of the base station 203 shown in FIG. 2. The transmission process of the base station 203 shown in FIG. 9 will be described. The EPC communication unit 401 transmits and receives data between the base station 203 and the EPC (such as the MME unit 204), the HeNB GW 205, etc. The 5GC communication unit 412 transmits and receives data between the base station 203 and the 5GC (such as the 5GC unit 214). The other base station communication unit 402 transmits and receives data with other base stations. The EPC communication unit 401, the 5GC communication unit 412, and the other base station communication unit 402 each exchange information with the protocol processing unit 403. The control data from the protocol processing unit 403, as well as the user data and control data from the EPC communication unit 401, the 5GC communication unit 412, and the other base station communication unit 402, are stored in the transmission data buffer unit 404.

[0089] The data stored in the transmission data buffer unit 404 is passed to the encoder unit 405, and encoding processing such as error correction is performed. There may be data that is directly output from the transmission data buffer unit 404 to the modulation unit 406 without undergoing the encoding process. The encoded data is subjected to modulation processing in the modulation unit 406. Precoding in MIMO may be performed in the modulation unit 406. The modulated data is converted into a baseband signal and then output to the frequency conversion unit 407, where it is converted to a radio transmission frequency. Thereafter, a transmission signal is transmitted to one or more mobile terminals 202 from the antennas 408-1 to 408-4. In FIG. 9, the case where the number of antennas is 4 is illustrated, but the number of antennas is not limited to 4.

[0090] Also, the reception processing of the base station 203 is executed as follows. A radio signal from one or more mobile terminals 202 is received by the antenna 408. The received signal is converted from the radio reception frequency to a baseband signal by the frequency conversion unit 407, and demodulation processing is performed by the demodulation unit 409. The demodulated data is passed to the decoder unit 410, and decoding processing such as error correction is performed. Among the decoded data, the control data is passed to the protocol processing unit 403, the EPC communication unit 401, or the other base station communication unit 402, and the user data is passed to the EPC communication unit 401 and the other base station communication unit 402. A series of processes of the base station 203 is controlled by the control unit 411. Therefore, although omitted in FIG. 4, the control unit 411 is connected to each of the units 401 to 410. In FIG. 9, the number of antennas used for transmission by the base station 203 and the number of antennas used for reception may be the same or different.

[0091] FIG. 9 is a block diagram showing the configuration of the base station 203, but the base station 213 may have a similar configuration. Also, regarding FIGS. 8 and 9, the number of antennas of the mobile terminal 202 and the number of antennas of the base station 203 may be the same or different.

[0092] FIG. 10 is a block diagram showing the configuration of the MME. FIG. 10 shows the configuration of the MME 204a included in the MME unit 204 shown in FIG. 2 above. The PDN GW communication unit 501 transmits and receives data between the MME 204a and the PDN GW. The base station communication unit 502 transmits and receives data via the S1 interface between the MME 204a and the base station 203. When the data received from the PDN GW is user data, the user data is passed from the PDN GW communication unit 501 to the base station communication unit 502 via the user plain communication unit 503 and transmitted to one or more base stations 203. When the data received from the base station 203 is user data, the user data is passed from the base station communication unit 502 to the PDN GW communication unit 501 via the user plain communication unit 503 and transmitted to the PDN GW.

[0093] When the data received from the PDN GW is control data, the control data is passed from the PDN GW communication unit 501 to the control plane control unit 505. When the data received from the base station 203 is control data, the control data is passed from the base station communication unit 502 to the control plane control unit 505.

[0094] The HeNBGW communication unit 504 is provided when the HeNBGW 205 exists, and performs data transmission and reception via the interface (IF) between the MME 204a and the HeNBGW 205 according to the information type. The control data received from the HeNBGW communication unit 504 is passed from the HeNBGW communication unit 504 to the control plane control unit 505. The result of the processing in the control plane control unit 505 is transmitted to the PDN GW via the PDN GW communication unit 501. Also, the result processed by the control plane control unit 505 is transmitted to one or more base stations 203 via the S1 interface via the base station communication unit 502, and is also transmitted to one or more HeNBGWs 205 via the HeNBGW communication unit 504.

[0095] The control plane control unit 505 includes a NAS security unit 505-1, an SAE bearer control unit 505-2, an idle state mobility management unit 505-3, etc., and performs overall processing for the control plane (hereinafter, may also be referred to as the C-Plane). The NAS security unit 505-1 performs security of NAS (Non-Access Stratum) messages, etc. The SAE bearer control unit 505-2 performs management of SAE (System Architecture Evolution) bearers, etc. The idle state mobility management unit 505-3 performs mobility management in the standby state (idle state; LTE-IDLE state, or simply referred to as idle), generation and control of paging signals in the standby state, addition, deletion, update, search, and tracking area list management of the tracking area of one or more mobile terminals 202 under its umbrella.

[0096] MME204a distributes paging signals to one or more base stations 203. Also, MME204a performs mobility control in the Idle State. MME204a manages the Tracking Area list when the mobile terminal is in the idle state and in the Active State. MME204a initiates the paging protocol by transmitting a paging message to a cell belonging to the tracking area (Tracking Area) in which the UE is registered. The management of the CSG of the Home-eNB206 connected to MME204a, the management of the CSG ID, and the management of the whitelist may be performed by the idle state mobility management unit 505-3.

[0097] FIG. 11 is a block diagram showing the configuration of the 5GC. In FIG. 11, the configuration of the 5GC unit 214 shown in FIG. 3 described above is shown. FIG. 11 shows the case where the configuration of the AMF, the configuration of the SMF, and the configuration of the UPF are included in the 5GC unit 214 shown in FIG. 5. The Data Network communication unit 521 transmits and receives data between the 5GC unit 214 and the Data Network. The base station communication unit 522 transmits and receives data via the S1 interface between the 5GC unit 214 and the base station 203 and / or the NG interface between the 5GC unit 214 and the base station 213. When the data received from the Data Network is user data, the user data is passed from the Data Network communication unit 521 to the base station communication unit 522 via the user plain communication unit 523 and transmitted to one or more of the base stations 203 and / or the base station 213. When the data received from the base station 203 and / or the base station 213 is user data, the user data is passed from the base station communication unit 522 to the Data Network communication unit 521 via the user plain communication unit 523 and transmitted to the Data Network.

[0098] When the data received from the Data Network is control data, the control data is passed from the Data Network communication unit 521 to the session management unit 527. The session management unit 527 passes the control data to the control plane control unit 525. When the data received from the base station 203 and / or the base station 213 is control data, the control data is passed from the base station communication unit 522 to the control plane control unit 525. The control plane control unit 525 passes the control data to the session management unit 527.

[0099] The control plane control unit 525 includes a NAS security unit 525-1, a PDU session control unit 525-2, an idle state mobility management unit 525-3, etc., and performs overall processing for the control plane (hereinafter, may also be referred to as the C-Plane). The NAS security unit 525-1 performs security of NAS (Non-Access Stratum) messages, etc. The PDU session control unit 525-2 performs management of the PDU session between the mobile terminal 202 and the 5GC unit 214, etc. The idle state mobility management unit 525-3 performs mobility management in the standby state (idle state; RRC_IDLE state, or simply referred to as idle), generation and control of paging signals in the standby state, addition, deletion, update, search, tracking area list management, etc. of the tracking area of one or more mobile terminals 202 under its umbrella.

[0100] The 5GC unit 214 distributes paging signals to one or more base stations 203 and / or base station 213. Also, the 5GC unit 214 performs mobility control in the idle state. When the mobile terminal is in the idle state, the 5GC unit 214 manages the tracking area list in the inactive state and the active state. The 5GC unit 214 initiates the paging protocol by transmitting a paging message to a cell belonging to the tracking area (tracking area) in which the UE is registered.

[0101] Next, an example of a cell search method in a communication system is shown. FIG. 12 is a flowchart showing an overview from cell search to standby operation performed by a communication terminal (UE) in an LTE-based communication system. When the communication terminal starts cell search, in step ST601, it synchronizes slot timing and frame timing using the first synchronization signal (P-SS) and the second synchronization signal (S-SS) transmitted from surrounding base stations.

[0102] The P-SS and S-SS are combined and called the synchronization signal (SS). A synchronization code corresponding one-to-one to the PCI assigned to each cell is assigned to the synchronization signal (SS). 504 types of PCI are being considered. Synchronization is performed using these 504 types of PCI, and the PCI of the synchronized cell is detected (identified).

[0103] Next, for the cell that has been synchronized, in step ST602, a Cell-specific Reference Signal (CRS), which is a reference signal (Reference Signal: RS) transmitted from the base station for each cell, is detected, and the received power of the RS (Reference Signal Received Power: RSRP) is measured. A code corresponding one-to-one to the PCI is used for the reference signal (RS). By correlating with that code, it can be separated from other cells. By deriving the code for the RS of the cell from the PCI specified in step ST601, it becomes possible to detect the RS and measure the received power of the RS.

[0104] Next, in step ST603, from among the one or more cells detected up to step ST602, a cell with the best reception quality of the RS is selected, for example, a cell with the highest received power of the RS, that is, the best cell.

[0105] Next, in step ST604, the PBCH of the best cell is received to obtain the BCCH, which is the broadcast information. The MIB (Master Information Block), which contains cell configuration information, is mapped to the BCCH on the PBCH. Therefore, by receiving the PBCH and obtaining the BCCH, the MIB can be obtained. Examples of the information in the MIB include the DL (downlink) system bandwidth (also called the transmission bandwidth configuration: dl-bandwidth), the number of transmission antennas, the SFN (System Frame Number), etc.

[0106] Next, in step ST605, based on the cell configuration information in the MIB, the DL-SCH of the cell is received to obtain the SIB (System Information Block) 1 in the broadcast information BCCH. The SIB1 contains information related to access to the cell, information related to cell selection, and scheduling information for other SIBs (SIBk; k is an integer greater than or equal to 2). Also, the SIB1 contains the Tracking Area Code (TAC).

[0107] Next, in step ST606, the communication terminal compares the TAC of SIB1 received in step ST605 with the TAC part of the Tracking Area Identity (TAI) in the tracking area list that the communication terminal already has. The tracking area list is also referred to as the TAI list. TAI is identification information for identifying a tracking area, and is composed of an MCC (Mobile Country Code), an MNC (Mobile Network Code), and a TAC (Tracking Area Code). The MCC is a country code. The MNC is a network code. The TAC is a code number of the tracking area.

[0108] As a result of the comparison in step ST606, if the TAC received in step ST605 is the same as the TAC included in the tracking area list, the communication terminal enters the standby operation in the cell. If the comparison shows that the TAC received in step ST605 is not included in the tracking area list, the communication terminal requests a change of the tracking area to perform a Tracking Area Update (TAU) to the core network (Core Network, EPC) including an MME or the like through the cell.

[0109] In the example shown in FIG. 12, an example of the operation from cell search to standby in the LTE system has been shown. In the NR system, in step ST603, in addition to the best cell, the best beam may be selected. Also, in the NR system, in step ST604, beam information, for example, a beam identifier may be acquired. Also, in the NR system, in step ST604, the scheduling information of the Remaining Minimum SI (RMSI) may be acquired. In the NR system, in step ST605, it may be assumed that the RMSI is received.

[0110] The device that constitutes the core network (hereinafter sometimes referred to as the "core network side device") updates the tracking area list based on the identification number (such as UE-ID) of the communication terminal sent from the communication terminal together with the TAU request signal. The core network side device transmits the updated tracking area list to the communication terminal. The communication terminal rewrites (updates) the TAC list held by the communication terminal based on the received tracking area list. Thereafter, the communication terminal enters the standby operation in the cell.

[0111] Due to the spread of smartphones and tablet terminal devices, traffic by cellular wireless communication has increased explosively, and there is concern about a shortage of radio resources worldwide. In response to this, in order to improve the frequency utilization efficiency, it has been considered to reduce the cell size and promote spatial separation.

[0112] In the configuration of a conventional cell, a cell constituted by an eNB has a relatively wide coverage area. Conventionally, cells have been configured to cover a certain area by the relatively wide coverage areas of a plurality of cells constituted by a plurality of eNBs.

[0113] When the cell size is reduced, a cell constituted by an eNB has a coverage area that is narrower than that of a cell constituted by a conventional eNB. Therefore, in order to cover a certain area as in the conventional case, a larger number of small cells formed by eNBs are required compared to conventional eNBs.

[0114] In the following description, a cell with a relatively large coverage area, such as a cell constituted by a conventional eNB, is referred to as a "macro cell", and an eNB that constitutes a macro cell is referred to as a "macro eNB". Also, a cell with a relatively small coverage area, such as a small cell, is referred to as a "small cell", and an eNB that constitutes a small cell is referred to as a "small eNB".

[0115] The macro eNB may be, for example, the "Wide Area Base Station" described in Non-Patent Document 7.

[0116] The small eNB may be, for example, a low-power node, a local area node, a hot spot, etc. Also, the small eNB may be a pico eNB constituting a picocell, a femto eNB constituting a femtocell, a HeNB, an RRH (Remote Radio Head), an RRU (Remote Radio Unit), an RRE (Remote Radio Equipment), or an RN (Relay Node). Also, the small eNB may be the "Local Area Base Station" or the "Home Base Station" described in Non-Patent Document 7.

[0117] Figure 13 shows an example of the cell configuration in NR. In an NR cell, a narrow beam is formed and transmitted while changing the direction. In the example shown in Figure 13, at a certain time, the base station 750 performs transmission and reception with the mobile terminal using the beam 751-1. At other times, the base station 750 performs transmission and reception with the mobile terminal using the beam 751-2. Similarly hereinafter, the base station 750 performs transmission and reception with the mobile terminal using one or more of the beams 751-3 to 751-8. By doing so, the base station 750 constitutes a wide range of cells.

[0118] In Figure 13, an example where the number of beams used by the base station 750 is 8 is shown, but the number of beams may be different from 8. Also, in the example shown in Figure 13, the number of beams used by the base station 750 simultaneously is 1, but it may be plural.

[0119] In NR, RRC_INACTIVE has been added as a state between the base station and the mobile terminal in RRC. In RRC_INACTIVE, among the connections between the upper-layer NW device and the mobile terminal, the connection between the upper-layer NW device and the base station is maintained. Also, in RRC_INACTIVE, system information (SI) notification, paging, cell re-selection, mobility, etc. are performed.

[0120] A UE using a DC configuration where the upper-layer NW device is a 5G core (hereinafter may be referred to as 5GC) may maintain the configuration of the secondary base station during RRC_INACTIVE transition. The configuration of the secondary base station may be, for example, the setting of SDAP (Service Data Adaptation Protocol; see Non-Patent Document 21) in the secondary node (SN), or the setting of PDCP in the secondary base station, or both of the above.

[0121] However, the operation of the UE when a UE using a DC configuration enters the RRC_INACTIVE state and the serving base station changes due to cell re-selection is not disclosed. As a result, for example, a problem occurs in that unnecessary data transmission and reception occur between the UE and the secondary base station due to a conflict in the DC configuration between the UE and the base station.

[0122] A solution to the above problem is disclosed below.

[0123] A UE in RRC_INACTIVE maintains the setting of the secondary base station after cell re-selection. When the serving base station of the UE changes due to cell re-selection, the above operation may be applied.

[0124] As described above, the UE may determine a secondary base station. For example, the UE may use cell reselection to determine a secondary base station. By doing so, for example, it becomes unnecessary for the UE to report measurement results to the master base station, and as a result, the signaling volume between the UE and the base station can be reduced.

[0125] When the UE determines a secondary base station, the UE may perform measurements of neighboring cells periodically. The period may be determined by the standard. Alternatively, the period may be the same as the DRX period.

[0126] Alternatively, the UE may perform measurements of neighboring cells when receiving paging. This enables reduction of the processing volume of the UE in the RRC_INACTIVE state.

[0127] The UE notifies the master base station of information regarding the determined secondary base station. The information may be, for example, an identifier of the secondary base station, or an identifier of a cell belonging to the secondary base station, such as a physical cell ID (Physical Cell Identity) of a PSCell. The information may be included in RRC individual signaling from the UE to the master base station, such as an RRC connection resume request (RRCConnectionResumeRequest), or may be included in small data that can be transmitted in the RRC_INACTIVE state.

[0128] As described above, the setting of the secondary base station may be, for example, an SDAP setting of the secondary base station, a PDCP setting, or both of the above. By doing so, for example, among the connections between the UE and the upper NW device, the connection between the upper NW device and the secondary base station can be quickly restored.

[0129] The UE may maintain the RLC configuration of the secondary base station. This can, for example, reduce the throughput of the UE when returning to RRC_CONNECTED. As another example, the UE may release the RLC configuration of the secondary base station. This can, for example, enable appropriate radio parameter settings using the radio channel status when returning to RRC_CONNECTED. The same may apply to the MAC configuration and / or PHY configuration of the secondary base station.

[0130] The UE may maintain the configuration of the master base station. The configuration described above may be the same as that of the secondary base station. For example, it may be the SDAP configuration, the PDCP configuration, or both of the above. This can, for example, reduce the throughput when the UE returns to RRC_CONNECTED.

[0131] As another example, the UE may release the configuration of the master base station. For example, when the UE connects to a cell different from the original cell during cell reselection, the configuration of the master base station may be released. This can, for example, enable the UE to communicate with the base station using the radio channel status of the reselected cell and appropriate radio parameters. As another example regarding the release of the master base station configuration, when the UE returns to RRC_CONNECTED, the configuration of the master base station may be released. This can, for example, reduce the throughput in the UE.

[0132] The UE itself may initiate the release of the configuration of the master base station. In the above, the timing at which the UE releases the configuration of the master base station may be determined in advance by a standard or the like. This can, for example, reduce the signaling amount between the base station and the UE in the release of the configuration of the master base station by the UE.

[0133] As another example, the source master base station may initiate the release of the master base station setting in the UE. The source master base station may instruct the UE to release the master base station setting in the UE. The instruction may be notified to the UE via the target master base station. This can improve the flexibility regarding the timing of releasing the master base station setting in the UE, for example.

[0134] As another example, the target master base station may initiate the release of the master base station setting in the UE. The target master base station may instruct the UE to release the master base station setting in the UE. The instruction may be included in other signaling from the target base station to the UE, for example, signaling instructing a return to RRC_CONNECTED, or may be included in signaling instructing the maintenance of RRC_INACTIVE. This can reduce the signaling between the target base station and the source base station, for example.

[0135] As another example, the upper-layer NW device (e.g., 5GC) may initiate the release of the master base station setting in the UE. For example, the upper-layer NW device may perform the release of the master base station setting in the UE when the RAN area of the UE is updated. This can enable the upper-layer NW device to execute a master base station setting suitable for the updated RAN area when the RAN area of the UE is updated, for example.

[0136] The source master base station may hold the setting of the secondary base station in the UE. The setting held in the master base station may be the same as the setting of the secondary base station maintained by the UE. The master base station may hold information regarding the secondary base station, for example, the identifier of the secondary base station, together with the setting. This can enable the master base station to identify the secondary base station in the DC configuration with the UE, for example.

[0137] The target master base station may inquire of the source master base station about information regarding the setting of the secondary base station in the UE. The source master base station may notify the target master base station of the information. The aforementioned inquiry and / or notification may be performed after an RRC_CONNECTED transition request of the UE itself, which is transmitted from the UE to the target master base station. As a result, for example, it becomes unnecessary for the source base station to notify the information in advance to surrounding base stations including the target master base station. Consequently, the amount of signaling between base stations can be reduced.

[0138] As another example, the aforementioned inquiry and / or notification may be performed before an RRC_CONNECTED transition request of the UE itself, which is transmitted from the UE to the target master base station. As a result, for example, the UE can quickly transition to RRC_CONNECTED while maintaining the DC configuration.

[0139] The source master base station may release the setting of the secondary base station by using signaling from the target master base station. The signaling may be, for example, signaling for UE context release. As a result, for example, in the source master base station, it becomes possible to prevent buffer congestion caused by holding the secondary base station setting in the subordinate UE.

[0140] The secondary base station may hold the setting of its own secondary base station in the UE. The setting held in the secondary base station may be the same as the setting of the secondary base station maintained by the UE. As a result, for example, it becomes possible to reduce the buffer usage amount due to holding the setting in the master base station.

[0141] The UE re-establishes the PDCP for the master base station and / or the secondary base station. In this re-establishment, the settings of the master base station and / or the secondary base station maintained by the UE may be used. The UE may perform this re-establishment using the signaling of the RRC_CONNECTED resume indication notified from the target master base station. The signaling may not include information regarding the settings of the master base station and / or the secondary base station, for example, the parameters of the settings (e.g., PDCP-Config in Non-Patent Document 19 (3GPP TS36.331 V15.1.0)). Thereby, for example, the size of the signaling can be reduced.

[0142] The master base station may instruct the UE to perform the above-mentioned re-establishment of the PDCP. The master base station may notify the UE of the instruction, for example, included in the signaling of the RRC_CONNECTED resume indication. The UE may perform the above-mentioned re-establishment of the PDCP using the instruction. Alternatively, the UE may not perform the above-mentioned re-establishment of the PDCP using the absence of the instruction.

[0143] As another example, the master base station may not notify the UE of the instruction to re-establish the above-mentioned PDCP. The UE may, for example, perform the above-mentioned re-establishment of the PDCP using the signaling of the RRC_CONNECTED resume indication. Thereby, for example, the size of the signaling between the master base station and the UE can be reduced.

[0144] The signaling of the above-mentioned RRC_CONNECTED resume indication may include the identifier of the UE. As the identifier, for example, I-RNTI (see Non-Patent Document 16) may be used. The identifier may be unique, for example, within the base station, within the RAN area, or within the 5GC. By being unique within the RAN area, for example, even when the base station is changed due to cell reselection of the UE, the base station can identify the UE.

[0145] As another example of the identifier, a C-RNTI may be used. The aforementioned C-RNTI may be the one assigned when the UE is in the RRC_CONNECTED state, and may be used in combination with the PCI. This enables, for example, the direct use of the identifier at the time of RRC_CONNECTED, eliminating the need for re-assignment of the identifier at the base station. As a result, the processing load in the communication system can be reduced.

[0146] When the identifier is unique within the RAN area, the identifier may be updated during RAN area update. For example, when the UE selects a base station in a different RAN area during cell reselection, the base station may notify the UE of a new identifier. This notification may be performed, for example, in the procedure of RAN area update (see Section 9.2.2.5 of Non-Patent Document 16). This enables the base station to identify the UE even when the UE moves to a different RAN area during cell reselection.

[0147] When the UE maintains the settings of the secondary base station after cell reselection, the secondary base station may change its own settings for connection with the UE. The settings may be, for example, SDAP and / or PDCP settings. The secondary base station may notify the source master base station of the changed settings. As such notification, for example, a Secondary Node Addition Request ACK may be used. The source master base station may notify the UE of the changed settings. The UE may use the settings to change the settings of the secondary base station. This enables, for example, the use of efficient settings in the combination of the master base station and the secondary base station in the communication system, and as a result, the communication efficiency in the communication system can be improved.

[0148] Figures 14 and 15 are sequence diagrams showing the operations in which a UE using a DC configuration maintains the secondary base station settings and transitions to RRC_CONNECTED when connecting to different master base stations during cell reselection. Figure 14 and Figure 15 are connected at the position of the boundary line BL1415. In Figures 14 and 15, the source master base station is designated as S-MgNB, the target master base station is designated as T-MgNB, and the secondary base station is designated as SeNB. Figures 14 and 15 show an example in which the UE initiates a transition to RRC_CONNECTED.

[0149] In step ST801 shown in Figure 14, the UE is in the RRC_INACTIVE state. In step ST802, the UE performs cell reselection, and the connected base station switches from S-MgNB to T-MgNB. In step ST803, the UE maintains the SDAP / PDCP settings of the SeNB.

[0150] In steps ST805 and ST806 shown in Figure 14, random access processing is performed between the UE and the T-MgNB. In step ST805, the UE transmits a random access preamble to the T-MgNB. In step ST806, the T-MgNB transmits a random access response to the UE. In the example of Figure 14, it is assumed that the random access processing is successful in step ST806.

[0151] In step ST807 shown in Figure 14, the UE requests the resumption of the RRC connection from the T-MgNB. For this request, for example, signaling of an RRC connection resume request (RRCConnectionResumeRequest) may be used. This signaling may include an identifier of the UE, for example, an identifier assigned at the time of transition to RRC_INACTIVE (e.g., I-RNTI). The T-MgNB uses this identifier to identify the UE that requests the resumption of the RRC connection.

[0152] In step ST810 shown in FIG. 14, T-MgNB makes a request for obtaining the UE context to S-MgNB. For example, signaling such as UE Context Retrieve Request may be used for this request. This request may be made, for example, using the interface between base stations (e.g., X2 / Xn). Information regarding the request for obtaining the secondary base station setting may be included in this request.

[0153] In step ST811 shown in FIG. 14, S-MgNB makes a request for obtaining the secondary base station setting to SeNB. For example, signaling similar to that in step ST810 may be used for this request. In step ST812, SeNB notifies S-MgNB of the secondary base station setting. For example, signaling (UE Context Retrieve Response) used for the response to the UE context acquisition may be used for this signaling. S-MgNB obtains the secondary base station setting in step ST812.

[0154] In step ST813 shown in FIG. 14, S-MgNB notifies T-MgNB of the UE context. For example, signaling such as UE Context Retrieve Response may be used for this notification. This notification may be made, for example, using the interface between base stations (e.g., X2 / Xn). The secondary base station setting included in step ST812 is included in this notification. T-MgNB obtains the UE context including the secondary base station setting in step ST813.

[0155] In step ST815 in FIG. 15, T-MgNB notifies SeNB of a secondary base station addition request (SN Addition Request). The request may include the secondary base station settings obtained from SeNB in step ST813. In the example of FIG. 15, SeNB determines to accept the request. In step ST816, SeNB notifies T-MgNB of a positive response to the request (secondary base station addition request positive response; SN Addition Request ACK).

[0156] In step ST820 in FIG. 15, S-MgNB notifies SeNB of a secondary base station release request (SN Release Request). In step ST821, SeNB notifies S-MgNB of a secondary base station release request acknowledgement (SN Release Request Acknowledge).

[0157] In step ST825 in FIG. 15, T-MgNB instructs UE to resume the RRC connection. For the instruction, for example, signaling for RRC connection resume (RRCConnectionResume) may be used. The signaling may include the identifier of UE. The identifier may be, for example, I-RNTI. The signaling may include C-RNTI. The signaling may include both of the foregoing. As another example, the signaling may include information about the source base station. The information may be, for example, the identifier of the source base station (e.g., gNB-ID) or the identifier of the PCell (e.g., PCI). Thereby, for example, T-MgNB can quickly obtain information about S-MgNB.

[0158] In step ST826 in FIG. 15, the UE re - establishes the PDCP for the T - MgNB and the SeNB, and resets the RLC and MAC. In step ST826, the UE uses the SDAP configuration as it is. In step ST827, the UE transitions to RRC_CONNECTED. In step ST827, the UE may discard the I - RNTI.

[0159] In step ST828 shown in FIG. 15, the UE notifies the T - MgNB that the RRC connection has been resumed. For example, signaling such as RRCConnectionResumeComplete may be used for this notification.

[0160] In step ST829 shown in FIG. 15, the T - MgNB requests the SeNB to resume the connection with the UE. The resumption may be, for example, the resumption of the SCG bearer, the SCG - side path of the SCG split bearer, and the SCG - side path of the MCG split bearer. In step ST829, the connection between the T - MgNB, the SeNB, and the UE is resumed.

[0161] In steps ST830 and ST831 shown in FIG. 15, random access processing is performed between the UE and the SeNB. In step ST830, the UE transmits a random access preamble to the SeNB. The random access preamble may be the random access preamble notified from the T - MgNB to the UE in step ST825. In step ST831, the SeNB notifies the UE of a random access response.

[0162] In step ST835 shown in FIG. 15, T-MgNB requests a communication path switch (Path Switch Request) from the AMF. The request may include a request for a PDU session switch in the T-MgNB and the SeNB. In step ST835, a communication path switch is performed between the AMF and the UPF. A PDU session switch may be performed in the MgNB and the SgNB.

[0163] In step ST836 shown in FIG. 15, the AMF notifies T-MgNB of the completion of the communication path switch (Path Switch Complete). In step ST837, T-MgNB instructs the S-MgNB to release the UE context for the MgNB (UE context release).

[0164] In the example shown in FIGS. 14 and 15, the case where the UE itself initiates the transition operation to RRC_CONNECTED is shown, but it may also be applied when the network initiates the transition operation of the UE to RRC_CONNECTED. In the above case, the S-MgNB may send a RAN paging to the T-MgNB. The T-MgNB may also send a paging to the UE. The paging may be performed after the RAN paging from the S-MgNB to the T-MgNB. After the paging is sent from the T-MgNB to the UE, random access processing between the UE and the T-MgNB shown in steps ST805 and ST806 may be performed. Similarly, in the following figures, it may be applied when the network initiates the transition operation of the UE to RRC_CONNECTED. As a result, for example, even when downlink data is generated, the UE can quickly resume the DC configuration.

[0165] In the examples shown in FIGS. 14 and 15, as step ST821, the case where the SeNB transmits a secondary base station release request positive response to the S-MgNB was shown, but it may not transmit the response. After transmitting the secondary base station release request shown as step ST820 to the SeNB, the S-MgNB may automatically recognize that the secondary base station release has been completed. This can reduce, for example, the signaling between base stations.

[0166] In the examples shown in FIGS. 14 and 15, the case where step ST812 is performed after step ST811 was shown, but the secondary base station configuration may be transmitted from the SeNB to the S-MgNB in advance. For example, the SeNB may perform step ST812 using the fact that the UE has transitioned to RRC_INACTIVE. In the foregoing, for example, the S-MgNB may not perform step ST811. This can enable, for example, the T-MgNB to quickly acquire the secondary base station configuration.

[0167] In the examples shown in FIGS. 14 and 15, the case where the S-MgNB requests a secondary base station configuration as step ST811 was shown, but the S-MgNB may not perform step ST811. For example, in the case where the S-MgNB holds the configuration of the SeNB (e.g., SDAP / PDCP configuration), the S-MgNB may not perform step ST811. This can reduce, for example, the amount of signaling between base stations.

[0168] In the examples shown in FIGS. 14 and 15, the case where the secondary base station release request and the secondary base station release request positive response shown as steps ST820 and ST821 are performed after the secondary base station addition request and the secondary base station addition request positive response shown as steps ST815 and ST816 was shown. However, the secondary base station release request and the secondary base station release request positive response may be performed before the secondary base station addition request and the secondary base station addition request positive response. This makes it possible to improve the flexibility of SeNB control in, for example, T-MgNB and S-MgNB.

[0169] In step ST816 shown in FIG. 15, an example where the SN setting is not changed from before RRC_INACTIVE was shown, but the SeNB may change the setting. The SeNB may include the changed setting in the notification of step ST816. The T-MgNB may include the changed setting in the notification of step ST825 to the UE. The UE may perform the transition operation to RRC_CONNECTED using the changed setting in step ST826. This makes it possible to use an efficient setting in, for example, the combination of the master base station and the secondary base station in a communication system, and as a result, improve the communication efficiency in the communication system.

[0170] In the examples shown in FIGS. 14 and 15, the case where steps ST810 to ST813 are performed before steps ST815 and ST816 was shown, but they may be performed later. In the case of performing them later, the S-MgNB and the SeNB may not perform the operations shown in steps ST811 and ST812. The T-MgNB may obtain the secondary base station setting using step ST816. This makes it possible to reduce the signaling between base stations, for example.

[0171] In the examples shown in FIGS. 14 and 15, the T-MgNB may be a T-MeNB. The S-MgNB may be an S-MeNB. The SeNB may be an SgNB.

[0172] Other solutions are disclosed. After cell reselection, the UE in RRC_INACTIVE releases the configuration of the secondary base station. When the serving base station of the UE changes due to cell reselection, the above operation may be applied. This can reduce, for example, the processing load in the UE. In the above, the configuration of the secondary base station may be, for example, the SDAP configuration of the secondary base station, or the PDCP configuration, or both of the above.

[0173] The UE may perform the release of the configuration, for example, when the UE connects to a cell different from the original cell in cell reselection. This can prevent unnecessary release of secondary configurations when the serving cell does not change in cell reselection. In the above, the cell may be a cell belonging to the master cell group (MCG) or a cell belonging to the secondary cell group (SCG).

[0174] The UE itself may initiate the release of the configuration of the secondary base station in the UE. In the above, the timing at which the UE releases the configuration may be defined in advance by a standard or the like. This can reduce, for example, the signaling volume between the base station and the UE in the release of the configuration by the UE.

[0175] As another example, the release of the configuration in the UE may be initiated by the source master base station. The source master base station may instruct the UE to release the configuration in the UE. The instruction may be notified to the UE via the target master base station. This can improve, for example, the flexibility regarding the timing of the release of the configuration in the UE.

[0176] As another example, the release of the setting in the UE may be initiated by the target master base station. The target master base station may instruct the UE to release the setting in the UE. The instruction may be included in other signaling from the target base station to the UE, for example, signaling instructing a return to RRC_CONNECTED, or may be included in signaling instructing the maintenance of RRC_INACTIVE. This can reduce, for example, the signaling between the target base station and the source base station.

[0177] As another example, the release of the setting in the UE may be initiated by a higher-layer NW device (e.g., 5GC). For example, the higher-layer NW device may release the setting in the UE when the RAN area of the UE is updated. This enables, for example, the higher-layer NW device to execute master base station settings suitable for the updated RAN area when the RAN area of the UE is updated.

[0178] When the UE releases the setting, the source master base station may not request the secondary base station to obtain secondary base station settings. This can reduce, for example, the base station-to-base station signaling.

[0179] Figures 16 and 17 are sequence diagrams showing the operations of a UE using a DC configuration to release secondary base station settings and transition to RRC_CONNECTED when connecting to different master base stations during cell reselection. Figures 16 and 17 are connected at the position of the boundary line BL1617. In Figure 16, the source master base station is denoted as S-MgNB, the target master base station is denoted as T-MgNB, and the secondary base station is denoted as SeNB. Figures 16 and 17 show an example in which the UE initiates a transition to RRC_CONNECTED. In Figures 16 and 17, the same numbers are assigned to the processes common to Figures 14 and 15, and the common explanations are omitted.

[0180] Steps ST801 and ST802 shown in Figure 16 are the same as those in Figure 14.

[0181] In step ST903 shown in FIG. 16, the UE releases the SDAP / PDCP configuration of the SeNB.

[0182] Steps ST805 to ST810 shown in FIG. 16 are the same as those in FIG. 14. In FIG. 16, the S-MgNB does not request the acquisition of the secondary base station configuration from the SeNB, and the SeNB does not notify the S-MgNB of the secondary base station configuration. In step ST813 shown in FIG. 16, the S-MgNB notifies the T-MgNB of the UE context. Different from FIG. 14, the secondary base station configuration is not included in this notification.

[0183] In step ST915 in FIG. 17, the T-MgNB notifies the SeNB of a secondary base station addition request (SN Addition Request). In the example of FIG. 17, the SeNB determines to accept this request. In step ST916, the SeNB notifies the T-MgNB of an affirmative response to this request (secondary base station addition request affirmative response; SN Addition Request ACK). This notification may include the secondary base station configuration, for example, one or a combination of settings of SDAP, PDCP, RLC, MAC, and PHY.

[0184] Steps ST820 and ST821 in FIG. 17 are the same as those in FIG. 15. In step ST822, the S-MgNB instructs the SeNB to release the UE context (UE Context Release). The SeNB releases the UE context in step ST822. Steps ST825 to ST837 are the same as those in FIG. 15.

[0185] Also in the examples shown in FIGS. 16 and 17, similar to FIGS. 14 and 15, it may not be necessary to transmit the secondary base station release request positive response shown in step ST821. After transmitting the secondary base station release request shown as step ST820 to the SeNB, the S-MgNB may automatically recognize that the secondary base station release has been completed. This can reduce, for example, inter-base station signaling.

[0186] Also in the examples shown in FIGS. 16 and 17, similar to FIGS. 14 and 15, it may be assumed that the secondary base station release request and the secondary base station release request positive response shown as steps ST820 and ST821 are performed before the secondary base station addition request and the secondary base station addition request positive response shown as steps ST915 and ST916. This can improve, for example, the flexibility of SeNB control in the T-MgNB and S-MgNB.

[0187] Also in the examples shown in FIGS. 16 and 17, similar to the examples shown in FIGS. 14 and 15, steps ST810 and ST813 may be performed after steps ST915 and ST916. The T-MgNB may obtain the secondary base station configuration using step ST916. This can enable the T-MgNB to quickly obtain the secondary base station configuration, for example.

[0188] In the examples shown in FIGS. 16 and 17, the T-MgNB may be the T-MeNB. The S-MgNB may be the S-MeNB. The SeNB may be the SgNB.

[0189] Another solution is disclosed. The master base station may determine whether the UE maintains or releases the secondary base station configuration and notify the UE. The master base station described above may be the source base station or the target base station. The UE may use the instruction to maintain or release the configuration.

[0190] The master base station may issue the instruction before the UE transitions to RRC_INACTIVE, i.e., when it is in RRC_CONNECTED. For example, the master base station may notify the UE of the instruction using the signaling for RRC connection reconfiguration. This can reduce the signaling volume between the base station and the UE when, for example, the UE transitions to RRC_INACTIVE.

[0191] As another example, the master base station may issue the instruction when the UE transitions to RRC_INACTIVE. For example, the master base station may notify the UE of the instruction using the signaling for RRC connection release. As a result, for example, the UE does not need to hold the instruction while maintaining RRC_CONNECTED, and thus the buffer volume in the UE can be reduced.

[0192] As a basis for the master base station to determine whether the UE should maintain or release the secondary base station configuration, for example, the fact that the master base station has switched, the fact that the secondary base station has switched, or both of the above may be used. As another example, information regarding the type of secondary base station (e.g., base station for IoT, base station for broadband communication, macro base station, base station for small cell) may be used. This enables the master base station to appropriately configure the secondary base station settings for the UE according to the type of secondary base station and reduce the signaling between base stations.

[0193] In Embodiment 1, the case where the UE determines the secondary base station has been described, but the master base station may also determine the secondary base station. The master base station may be, for example, the destination master base station. The master base station may determine the secondary base station using the measurement results notified from the UE, or may use, as the secondary base station, a base station with a small backhaul delay with respect to the master base station. Thereby, for example, the delay between the master base station and the secondary base station can be reduced. That is, by using, as the secondary base station, a base station with a small backhaul delay, the delay of the communication system can be reduced.

[0194] The UE may perform the measurement periodically. The period may be determined by a standard. Alternatively, the period may be the same as the DRX period. Alternatively, the period may be notified individually to the UE by the master base station. Alternatively, the period may be notified from the master base station to the subordinate UEs.

[0195] Alternatively, the UE may perform the measurement at the time of paging reception. Reduction of the processing amount of the UE in the RRC_INACTIVE state becomes possible.

[0196] The UE may notify the master base station of the measurement results. The UE may perform the notification using small data that can be transmitted in the RRC_INACTIVE state. Quick notification of the measurement results becomes possible. As another example, the UE may notify the results as a measurement report. Alternatively, the measurement results may be included in the signaling of the RRC connection resume request (RRCConnectionResumeRequest). The master base station may determine the secondary base station using the information. Thereby, for example, the master base station can set, as the secondary base station, a base station with good communication quality with the UE, and as a result, the transmission and reception rate of the UE in the communication system can be improved.

[0197] When determining the secondary base station, the master base station may use the cell reselection criteria. The UE may notify the master base station of the measurement results used for cell reselection.

[0198] Figures 18 and 19 are sequence diagrams showing the operations of a UE using a DC configuration when connecting to different master base stations during cell reselection, maintaining the secondary base station settings, and transitioning to RRC_CONNECTED. Figures 18 and 19 are connected at the position of the boundary line BL1819. Figures 18 and 19 show the case where the target master base station determines the secondary base station. Let the source master base station be S-MgNB, the target master base station be T-MgNB, and the secondary base station be SeNB. Figures 18 and 19 show an example where the UE initiates a transition to RRC_CONNECTED. In Figures 18 and 19, the same steps as those in Figures 14 and 15 are assigned the same step numbers, and common explanations are omitted.

[0199] Steps ST801 to ST806 shown in Figure 18 are the same as those in Figure 14.

[0200] In step ST1007 shown in Figure 18, the UE requests the resumption of the RRC connection to T-MgNB. This request may include the I-RNTI or the measurement results of neighboring cells. In step ST1008, T-MgNB determines the secondary base station using the measurement results. In the example shown in Figure 18, the secondary base station is assumed to be the same before and after RRC_INACTIVE.

[0201] Steps ST810 to ST821 shown in Figures 18 and 19 are the same as those in Figures 14 and 15.

[0202] In step ST1025 shown in FIG. 19, T-MgNB instructs the UE to resume RRC connection. For this instruction, for example, signaling of RRC connection resume (RRCConnectionResume) may be used. The signaling may include an identifier of the UE. The identifier may be, for example, I-RNTI. The signaling may include information about the secondary base station determined by T-MgNB. The information may be, for example, an identifier of the secondary base station. The UE uses the information to recognize that the secondary base station after resuming RRC_CONNECTED is the SeNB in FIGS. 18 and 19.

[0203] In the examples shown in FIGS. 18 and 19, the case where I-RNTI is used as the identifier of the UE is shown. However, similar to the examples shown in FIGS. 14 and 15, C-RNTI may be used. It may be used in combination with PCI. As a result, for example, the identifier at the time of RRC_CONNECTED can be used as it is, and reallocation of the identifier at the base station becomes unnecessary. As a result, the processing amount in the communication system can be reduced.

[0204] Also in the examples shown in FIGS. 18 and 19, similar to the examples shown in FIGS. 14 and 15, steps ST810 to ST813 may be performed after steps ST815 and ST816. When performed later, S-MgNB and SeNB may not perform the operations shown in steps ST811 and ST812. T-MgNB may obtain secondary base station settings using step ST816. As a result, for example, signaling between base stations can be reduced.

[0205] In the examples shown in FIGS. 18 and 19, T-MgNB may be T-MeNB. S-MgNB may be S-MeNB. SeNB may be SgNB.

[0206] According to Embodiment 1, it is possible to prevent the occurrence of a DC configuration mismatch between the UE and the base station, and as a result, it is possible to prevent the occurrence of unnecessary data transmission and reception between the UE and the secondary base station. Also, for example, by maintaining the secondary base station settings, a UE in the RRC_INACTIVE state can quickly transition to the RRC_CONNECTED state.

[0207] Modification Example 1 of Embodiment 1. In Embodiment 1, the case where only the master base station switches before and after RRC_INACTIVE is shown. However, the embodiment 1 may also be applied in the case where only the secondary base station switches before and after RRC_INACTIVE.

[0208] When only the secondary base station switches before and after RRC_INACTIVE, the UE may maintain the secondary base station settings. The master base station may request the acquisition of the settings from the source base station. The source secondary base station may notify the master base station of the settings.

[0209] The master base station may notify the destination secondary base station of the settings. The settings may be included in and notified by, for example, the signaling of a secondary base station addition request (SN Addition Request) from the master base station to the destination secondary base station. The destination secondary base station may determine whether to use the settings. The destination secondary base station may notify the master base station that it will use the settings. The notification may be included in and notified by, for example, the signaling of a secondary base station addition request acknowledgement (SN Addition Request Acknowledgement) from the destination secondary base station to the source base station. This makes it possible to execute the notification of the settings from the source secondary base station to the destination secondary base station with a small amount of signaling.

[0210] As another example, the target secondary base station may determine and use a secondary base station setting different from the setting. The target secondary base station may notify the master base station of a secondary base station setting different from the setting. The notification may be included in, for example, the signaling of a secondary base station addition request acknowledgement from the target secondary base station to the source base station. As a result, for example, between the target secondary base station and the UE, the setting can be flexibly changed according to the situation of the target secondary base station (for example, the line load situation, etc.). As a result, efficient communication is possible in the entire communication system.

[0211] Figures 20 and 21 are sequence diagrams showing the operations of a UE using a DC configuration to maintain the secondary base station setting and transition to RRC_CONNECTED when switching to different secondary base stations before and after RRC_INACTIVE. Figures 20 and 21 are connected at the position of the boundary line BL2021. In Figures 20 and 21, the master base station is designated as MgNB, the source secondary base station is designated as S-SeNB, and the target secondary base station is designated as T-SeNB. Figures 20 and 21 show an example in which the UE initiates a transition to RRC_CONNECTED. Also, Figures 20 and 21 show an example in which the master base station determines the secondary base station. In Figures 20 and 21, the same numbers are assigned to the processes common to Figures 14, 15, 18, and 19, and the common explanations are omitted.

[0212] Steps ST801 to ST806 shown in Figure 20 are the same as those in Figure 14. Also, steps ST1007 and ST1008 shown in Figure 20 are the same as those in Figure 18. In Figure 20, step ST1008 shows the case where MgNB determines T-SeNB as the secondary base station.

[0213] In step ST1211 shown in FIG. 20, MgNB requests S-SeNB to obtain secondary base station settings. A request similar to step ST811 shown in FIG. 14 may be used for this request. In step ST1212, S-SeNB notifies MgNB of the secondary base station settings. The settings may be, for example, settings related to SDAP and / or PDCP. A signaling similar to step ST812 shown in FIG. 14 may be used for this signaling.

[0214] In step ST1215 shown in FIG. 21, MgNB notifies T-SeNB of a secondary base station addition request (SN Addition Request). The request may include the secondary base station settings obtained in step ST1212. In step ST1216, T-SeNB notifies MgNB of a positive response to the request (secondary base station addition request positive response; SN Addition Request ACK). The notification may include, for example, settings related to RLC, MAC, and PHY among the secondary base station settings.

[0215] Steps ST820 and ST821 shown in FIG. 21 are the same as those in FIG. 14. Also, step ST1025 shown in FIG. 21 is the same as that in FIG. 19. The secondary base station identifier included in step ST1025 of FIG. 21 may be that of T-SeNB. Steps ST826 to ST837 are the same as those in FIG. 14.

[0216] In the examples shown in FIGS. 20 and 21, for step ST821, the case where S-SeNB transmits a secondary base station release request positive response to MgNB is shown, but it is also possible not to transmit the response. After transmitting the secondary base station release request shown as step ST820 to S-SeNB, MgNB may automatically recognize that the secondary base station release is completed. As a result, for example, inter-base station signaling can be reduced.

[0217] In the examples shown in FIGS. 20 and 21, the case where step ST1212 is performed after step ST1211 has been shown. However, the secondary base station setting may be transmitted from the S-SeNB to the MgNB in advance. For example, the S-SeNB may perform step ST1212 by using the fact that the UE has transitioned to RRC_INACTIVE. In the foregoing, for example, the MgNB may not perform step ST1211. As a result, for example, the MgNB can quickly acquire the secondary base station setting.

[0218] In the examples shown in FIGS. 20 and 21, the case where the MgNB requests the secondary base station setting as step ST1211 has been shown. However, the MgNB may not perform step ST1211. For example, in the case where the MgNB holds the setting of the S-SeNB (e.g., SDAP / PDCP setting), the MgNB may not perform step ST1211. As a result, for example, the amount of signaling between base stations can be reduced.

[0219] In the examples shown in FIGS. 20 and 21, the case where the secondary base station release request and the secondary base station release request positive response shown as steps ST820 and ST821 are performed after the secondary base station addition request and the secondary base station addition request positive response shown as steps ST1215 and ST1216 has been shown. However, the secondary base station release request and the secondary base station release request positive response may be performed before the secondary base station addition request and the secondary base station addition request positive response. As a result, for example, the flexibility of the secondary base station control in the MgNB can be improved.

[0220] In step ST1216 shown in FIG. 21, an example was shown where the SN setting (e.g., SDAP / PDCP setting) is not changed before RRC_INACTIVE, but the T-SeNB may change this setting. The SeNB may include the changed setting in the notification of step ST1216. The MgNB may include the changed setting in the notification of step ST1025 to the UE. The UE may perform the transition operation to RRC_CONNECTED using the changed setting in step ST826. As a result, for example, in a combination of a master base station and a secondary base station in a communication system, an efficient setting can be used, and as a result, the communication efficiency in the communication system can be improved.

[0221] In the examples shown in FIGS. 20 and 21, the MgNB may be the MeNB. The T-SeNB may be the T-SgNB. The S-SeNB may be the S-SgNB.

[0222] Another solution is disclosed. When only the secondary base station is switched before and after RRC_INACTIVE, the UE may release the secondary base station setting. The UE may execute the release of the setting at the timing disclosed in, for example, Embodiment 1. As a result, for example, the UE can use an appropriate setting according to the situation of the destination secondary base station (e.g., the radio channel situation between the UE and the base station, the load situation of the base station, etc.). As a result, the transmission and reception rate of the UE in the communication system can be improved.

[0223] Figures 22 and 23 are sequence diagrams showing the operations of a UE using a DC configuration to release the secondary base station settings and transition to RRC_CONNECTED when switching to different secondary base stations before and after RRC_INACTIVE. Figures 22 and 23 are connected at the position of the boundary line BL2223. In Figures 22 and 23, the master base station is MgNB, the source secondary base station is S-SeNB, and the target secondary base station is T-SeNB. Figures 22 and 23 show an example where the UE initiates a transition to RRC_CONNECTED. Also, Figures 22 and 23 show the case where the master base station determines the secondary base station. In Figures 22 and 23, the same numbers are assigned to the processes common to Figures 14 to 19, and the common explanations are omitted.

[0224] Steps ST801 and ST802 shown in Figure 22 are the same as those in Figure 14. Step ST903 is the same as that in Figure 16. Steps ST805 to ST806 are the same as those in Figure 14. Also, steps ST1007 and ST1008 shown in Figure 22 are the same as those in Figure 18. In Figure 22, step ST1008 shows the case where MgNB determines T-SeNB as the secondary base station.

[0225] Steps ST915 and ST916 shown in Figure 23 are the same as those in Figure 17.

[0226] Steps ST820 and ST821 shown in Figure 23 are the same as those in Figure 15. Also, step ST1025 shown in Figure 23 is the same as that in Figure 19. The secondary base station identifier included in step ST1025 of Figure 23 may be that of T-SeNB. Steps ST826 to ST837 are the same as those in Figure 15.

[0227] Also in the examples shown in FIGS. 22 and 23, similar to FIGS. 14, 15, 20, and 21, it may not be necessary to transmit the secondary base station release request positive response shown in step ST821. After MgNB transmits the secondary base station release request shown as step ST820 to S-SeNB, it may automatically recognize that the secondary base station release is completed. This can reduce, for example, the signaling between base stations.

[0228] Also in the examples shown in FIGS. 22 and 23, similar to FIGS. 14, 15, 20, and 21, it may be assumed that the secondary base station release request and the secondary base station release request positive response shown as steps ST820 and ST821 are performed before the secondary base station addition request and the secondary base station addition request positive response shown as steps ST915 and ST916. This can improve, for example, the flexibility of secondary base station control in MgNB.

[0229] In the examples shown in FIGS. 20 and 21, MgNB may be MeNB. T-SeNB may be T-SgNB. S-SeNB may be S-SgNB.

[0230] Another solution is disclosed. When only the secondary base station is switched before and after RRC_INACTIVE, the master base station may determine whether the UE maintains or releases the secondary base station settings and notify the UE. For the operation of the master base station to determine and notify the UE, the same method as in Embodiment 1 may be applied. This can obtain, for example, the same effects as in Embodiment 1.

[0231] As another example, the presence or absence of RAN area update of the secondary base station or information regarding the type of the secondary base station may be used for the master base station to determine whether the UE maintains or releases the setting of the secondary base station. The type of the secondary base station may be, for example, a base station for IoT, a base station for broadband, or other information. The master base station may determine, for example, to release the setting of the secondary base station by the UE using the fact that the type of the secondary base station is different before and after RRC_INACTIVE. As a result, for example, efficient operation in the communication system becomes possible according to the type of the secondary base station.

[0232] In the first modification example 1 of the first embodiment, the case where the master base station determines the secondary base station has been described, but the UE may determine the secondary base station. For example, steps ST1007 and ST1025 in FIGS. 20 and 21 may be replaced with steps ST807 and ST825 in FIGS. 14 and 15, respectively, and step ST1008 in FIG. 20 may be omitted. FIGS. 22 and 23 may be the same as FIGS. 20 and 21. As a result, for example, since it is not necessary to notify the master base station of measurement information from the UE, the signaling amount between the UE and the master base station can be reduced.

[0233] According to the first modification example 1 of the first embodiment, the same effects as those of the first embodiment can be obtained even when the secondary base station is switched before and after RRC_INACTIVE.

[0234] Modification example 2 of the first embodiment. In the first modification example 1 of the first embodiment, the case where only the secondary base station is switched before and after RRC_INACTIVE has been described, but the first embodiment may be applied when both the master base station and the secondary base station are switched before and after RRC_INACTIVE.

[0235] When both the master base station and the secondary base station are switched before and after RRC_INACTIVE, the UE may maintain the secondary base station settings. The target master base station may request the source secondary base station to obtain the settings via the source master base station. The source secondary base station may notify the target master base station of the settings via the source master base station.

[0236] The target master base station may notify the target secondary base station of the settings. The settings may be notified, for example, included in the signaling of a secondary base station addition request (SN Addition Request) from the target master base station to the target secondary base station. The target secondary base station may determine whether to use the settings. The target secondary base station may notify the target master base station that it will use the settings. The notification may be notified, for example, included in the signaling of a secondary base station addition request acknowledgement (SN Addition Request Acknowledgement) from the target secondary base station to the source base station. This enables, for example, the notification of the settings from the source secondary base station to the target secondary base station to be executed with a small amount of signaling.

[0237] As another example, the target secondary base station may determine and use secondary base station settings different from the settings. The target secondary base station may notify the target master base station of the secondary base station settings different from the settings. The notification may be notified, for example, included in the signaling of a secondary base station addition request acknowledgement (SN Addition Request Acknowledgement) from the target secondary base station to the source base station. This enables, for example, the settings to be flexibly changed according to the situation of the target secondary base station (for example, the line load situation, etc.) between the target secondary base station and the UE. As a result, efficient communication is possible in the entire communication system.

[0238] Figures 24 and 25 are sequence diagrams showing the operation of a UE using a DC configuration to maintain the secondary base station settings and transition to RRC_CONNECTED when switching to different master base stations and different secondary base stations before and after RRC_INACTIVE. Figures 24 and 25 are connected at the position of the boundary line BL2425. In Figures 24 and 25, the source master base station is denoted as S-MgNB, the target master base station is denoted as T-MgNB, the source secondary base station is denoted as S-SeNB, and the target secondary base station is denoted as T-SeNB. Figures 24 and 25 show an example in which the UE initiates a transition to RRC_CONNECTED. Also, Figures 24 and 25 show an example in which the master base station determines the secondary base station. In Figures 24 and 25, the same numbers are assigned to the processes common to Figures 14, 15, 18, and 19, and the common descriptions are omitted.

[0239] Steps ST801 to ST806 in Figure 24 are the same as those in Figure 14. Steps ST1007 and ST1008 are the same as those in Figure 18. Steps ST810 to ST821 are the same as those in Figure 14. Step ST1025 is the same as that in Figure 18. Steps ST826 to ST837 are the same as those in Figure 14.

[0240] In the example shown in Figures 24 and 25, the case where step ST812 is performed after step ST811 is shown. However, the secondary base station settings may be transmitted from S-SeNB to S-MgNB in advance. For example, S-SeNB may perform step ST812 using the fact that the UE has transitioned to RRC_INACTIVE. In the foregoing, for example, S-MgNB may not perform step ST811. As a result, for example, S-MgNB can quickly acquire the secondary base station settings.

[0241] In the examples shown in FIGS. 24 and 25, the case where S-MgNB requests secondary base station configuration as step ST811 has been shown, but S-MgNB may not perform step ST811. For example, when S-MgNB holds the configuration of S-SeNB (e.g., SDAP / PDCP configuration), S-MgNB may not perform step ST811. By doing so, for example, the amount of signaling between base stations can be reduced.

[0242] In the examples shown in FIGS. 24 and 25, the case where the secondary base station release request and the secondary base station release request positive response shown as steps ST820 and ST821 are performed after the secondary base station addition request and the secondary base station addition request positive response shown as steps ST815 and ST816 has been shown. However, the secondary base station release request and the secondary base station release request positive response may be performed before the secondary base station addition request and the secondary base station addition request positive response. By doing so, for example, the flexibility of the secondary base station in MgNB can be improved.

[0243] In step ST816 shown in FIG. 25, an example where the SN configuration (e.g., SDAP / PDCP configuration) is not changed from before RRC_INACTIVE has been shown, but SeNB may change the configuration. SeNB may include the changed configuration in the notification of step ST816. T-MgNB may include the changed configuration in the notification of step ST1025 to the UE. The UE may perform the transition operation to RRC_CONNECTED using the changed configuration in step ST826. By doing so, for example, in the combination of the master base station and the secondary base station in the communication system, an efficient configuration can be used, and as a result, the communication efficiency in the communication system can be improved.

[0244] In the examples shown in FIGS. 24 and 25, S-MgNB may be S-MeNB. T-MgNB may be T-MeNB. T-SeNB may be T-SgNB. S-SeNB may be S-SgNB.

[0245] Other solutions are disclosed. When both the master base station and the secondary base station switch before and after RRC_INACTIVE, the UE may release the secondary base station configuration. The UE may perform the release of the configuration, for example, at the timing disclosed in Embodiment 1. As a result, for example, the UE can use an appropriate configuration according to the situation of the destination secondary base station (for example, the radio channel situation between the UE and the base station, the load situation of the base station, etc.). As a result, the transmission and reception rate of the UE in the communication system can be improved.

[0246] Figures 26 and 27 are sequence diagrams showing the operation of a UE using a DC configuration to release the secondary base station configuration and transition to RRC_CONNECTED when switching between different master base stations and different secondary base stations before and after RRC_INACTIVE. Figures 26 and 27 are connected at the position of the boundary line BL2627. In Figures 26 and 27, the source master base station is denoted as S-MgNB, the destination master base station is denoted as T-MgNB, the source secondary base station is denoted as S-SeNB, and the destination secondary base station is denoted as T-SeNB. Figures 26 and 27 show an example in which the UE initiates a transition to RRC_CONNECTED. Also, Figures 26 and 27 show the case where the destination master base station determines the secondary base station. In Figures 26 and 27, the same numbers are assigned to the processes common to Figures 14 to 19, and the common descriptions are omitted.

[0247] Steps ST801 and ST802 shown in Figure 26 are the same as those in Figure 14. Step ST903 is the same as that in Figure 16. Steps ST805 to ST806 are the same as those in Figure 14. Also, steps ST1007 and ST1008 shown in Figure 26 are the same as those in Figure 18. In Figure 26, step ST1008 shows the case where MgNB determines T-SeNB as the secondary base station.

[0248] Steps ST915 and ST916 shown in Figure 27 are the same as those in Figure 15.

[0249] Steps ST820 and ST821 shown in FIG. 27 are the same as those in FIG. 14. Also, step ST1025 shown in FIG. 27 is the same as that in FIG. 19. The secondary base station identifier included in step ST1025 of FIG. 27 may be that of the T-SeNB. Steps ST826 to ST837 are the same as those in FIG. 14.

[0250] Also in the examples shown in FIGS. 26 and 27, similar to FIGS. 14, 15, 20, and 21, it may not be necessary to transmit the secondary base station release request positive response shown in step ST821. After MgNB transmits the secondary base station release request shown as step ST820 to the SeNB, it may automatically recognize that the secondary base station release is completed. This can reduce, for example, inter-base station signaling.

[0251] Also in the examples shown in FIGS. 26 and 27, similar to FIGS. 14, 15, 20, and 21, the secondary base station release request and the secondary base station release request positive response shown as steps ST820 and ST821 may be performed before the secondary base station addition request and the secondary base station addition request positive response shown as steps ST915 and ST916. This can improve, for example, the flexibility of SeNB control in T-MgNB and S-MgNB.

[0252] In the examples shown in FIGS. 26 and 27, S-MgNB may be S-MeNB. T-MgNB may be T-MeNB. T-SeNB may be T-SgNB. S-SeNB may be S-SgNB.

[0253] Other solutions are disclosed. When both the master base station and the secondary base station switch before and after RRC_INACTIVE, the master base station may determine whether the UE maintains or releases the settings of the secondary base station and notify the UE. The aforementioned master base station may be the target master base station or the source master base station. For the operation in which the aforementioned master base station determines whether to maintain or release the secondary base station settings in the UE and notifies the UE, a method similar to that in Embodiment 1 may be applied. Thereby, for example, the same effect as in Embodiment 1 can be obtained.

[0254] In this Modification 2 of Embodiment 1, the case where the target master base station determines the secondary base station is shown, but the UE may determine the secondary base station. Thereby, for example, since it is not necessary to notify the measurement information from the UE to the target master base station, the signaling amount between the UE and the target master base station can be reduced.

[0255] According to this Modification 2 of Embodiment 1, even when the master base station and the secondary base station switch before and after RRC_INACTIVE, the same effect as in Embodiment 1 can be obtained.

[0256] Embodiment 2. In DC by an LTE base station and an NR base station, the LTE base station determines the setting of the measurement gap in the frequency bands of LTE and FR1 of NR. The NR base station determines the setting of the measurement gap in the frequency band of FR2 of NR (see Non-Patent Document 22).

[0257] The NR base station may notify the LTE base station of candidates for the measurement gap that can be set by the own base station. The LTE base station may use this notification to determine the setting of the measurement gap in the frequency bands of LTE and FR1 of NR. The LTE base station may notify the NR base station of the setting of the measurement gap in the frequency bands of LTE and FR1 of NR. The NR base station may use this setting to perform scheduling in the frequency band of FR1 for the UE.

[0258] The NR base station may notify the LTE base station of the setting of the measurement gap in the frequency band of FR2 of NR. The LTE base station may use this setting to perform LTE scheduling for the UE, for example, transmission power setting.

[0259] In the above, the master base station may be an LTE base station or an NR base station.

[0260] When applying the above method to NR-DC, that is, when both the master base station and the secondary base station are NR base stations, the following problems occur. That is, since there is no LTE base station in NR-DC, it is impossible to set the measurement gap for FR1. As a result, in NR-DC, communication using FR1 becomes impossible, and problems such as a reduction in the coverage of the base station occur.

[0261] Also, in NR-DC, it is not disclosed which base station sets the measurement gaps for FR1 and FR2. For this reason, for example, if both the MgNB and the SgNB set the measurement gaps for the same frequency band section (e.g., FR1, FR2), the measurement gap is set excessively in the UE. As a result, problems such as a deterioration in the communication rate in the UE occur.

[0262] A method for solving the above problems is disclosed. Set the measurement gap for the frequency band section used by the local base station. For example, a base station using FR1 may set the measurement gap for FR1. A base station using FR2 may set the measurement gap for FR2. The above setting operation may be applied, for example, when the frequency band sections used between the MgNB and the SgNB are different. As a result, for example, adjustment between base stations in setting the measurement gap becomes unnecessary, and as a result, rapid setting of the measurement gap becomes possible.

[0263] Other solutions are disclosed. The frequency band division of the measurement gap set by each base station may be determined statically. For example, the MgNB may set both FR1 and FR2. The SgNB may notify the MgNB of candidates for the measurement gap settings that the local base station can support. The MgNB may notify the SgNB of the set measurement gap. This can avoid, for example, the complexity of the design related to the measurement gap setting in the communication system.

[0264] As another example when the frequency band division of the measurement gap set by each base station is determined statically, the MgNB may set the measurement gap for FR1, and the SgNB may set the measurement gap for FR2. The SgNB may notify the MgNB of candidates for the measurement gap settings that the local base station can support for FR1. The MgNB may notify the SgNB of the set measurement gap for FR1. Similarly, the MgNB may notify the SgNB of candidates for the measurement gap settings that the local base station can support for FR2. The SgNB may notify the MgNB of the set measurement gap for FR2. This can reduce, for example, the processing amount of the MgNB related to the measurement gap setting.

[0265] As another example, the MgNB may set the measurement gap for FR2, and the SgNB may set the measurement gap for FR1. The SgNB may notify the MgNB of candidates for the measurement gap settings that the local base station can support for FR2. The MgNB may notify the SgNB of the set measurement gap for FR2. Similarly, the MgNB may notify the SgNB of candidates for the measurement gap settings that the local base station can support for FR1. The SgNB may notify the MgNB of the set measurement gap for FR1. This can obtain, for example, the same effect as described above.

[0266] As another example, it may be determined using information regarding the type of the base station. The information may be, for example, that the base station is for IoT terminals or for broadband. Also, the information may be, for example, that the base station is a macro base station or a base station for small cells. For example, a base station for IoT terminals may set a measurement gap for FR1, or a base station for broadband may set a measurement gap for FR2. As another example, a macro base station may set a measurement gap for FR1, or a base station for small cells may set a measurement gap for FR2. This enables setting an appropriate measurement gap according to the use case of the communication performed between the base station and the UE.

[0267] The SgNB may notify the MgNB of information regarding the type of its own base station. The MgNB may notify the SgNB of information regarding the type of its own base station. The MgNB and the SgNB may recognize the type of the other base station using the information received from the other base station. This can prevent, for example, duplication and / or omission of settings between the two base stations.

[0268] As another example, it may be determined using information regarding the type of the UE. Such information may be, for example, that the UE is an IoT terminal or a broadband terminal, or other information. For example, for an IoT terminal, MgNB may set a measurement gap for FR1. As another example, for a broadband terminal, SgNB may set a measurement gap for FR2. Thus, an appropriate measurement gap can be set according to the use case of the communication performed between the base station and the UE, for example. Such information may be included in, for example, the UE capabilities or other signaling. The UE may notify such information to MgNB. MgNB may notify such information to SgNB. MgNB and SgNB may use such information to determine which of FR1 and FR2 the serving gNB should set the measurement gap for.

[0269] Another solution is disclosed. The frequency band division of the measurement gap set by each base station may be determined quasi-statically. For example, among the base stations communicating with the UE using the frequency band of FR1, a base station using a small subcarrier spacing, that is, a long symbol length, may set the measurement gap for the frequency band of FR1. Also, among the base stations communicating with the UE using the frequency band of FR2, a base station using a small subcarrier spacing, that is, a long symbol length, may set the measurement gap for the frequency band of FR2. SgNB may notify MgNB of the information on the subcarrier spacing used by SgNB in the communication with the UE. Such notification may be included in, for example, the RRC configuration notified from SgNB to UE via MgNB. MgNB may notify SgNB of the information on the subcarrier spacing used by MgNB in the communication with the UE. As a method of such notification, for example, a method of transferring the RRC configuration notified by MgNB to the UE from MgNB to SgNB may be used.

[0270] Other solutions are disclosed. It may inherit the measurement gap setting entity before mobility occurs. For example, in the case of NR-DC resulting from handover of the master base station in a DC where the master base station is an eNB and the secondary base station is a gNB, MgNB may perform the measurement gap setting for FR1 and SgNB may perform the measurement gap setting for FR2. As another example, in the case of NR-DC resulting from the switching of the secondary base station in a DC where the master base station is a gNB and the secondary base station is an eNB, MgNB may perform the measurement gap setting for FR2 and SgNB may perform the measurement gap setting for FR1. As another example, when mobility occurs from NR-DC to NR-DC using other base stations, the destination MgNB may set the measurement gap for the frequency band section set by the source MgNB, or the destination SgNB may set the measurement gap for the frequency section set by the destination SgNB. As a result, for example, the setting change after mobility occurs is reduced, and thus the processing amount in the communication system can be reduced. In the foregoing, the handover may be cell reselection.

[0271] Disclose other solutions. Regarding which frequency band division between FR1 and FR2 is set by which base station among MgNB and SgNB, it may be determined by MgNB. MgNB may notify SgNB of information regarding the frequency band division of the measurement gap set by the SgNB. Such notification may be included, for example, in the signaling (e.g., SgNB addition request, SgNB modification request, etc.) notified from MgNB to SgNB. By such notification, MgNB may notify candidates for measurement gap settings that can be supported in the frequency band division of the measurement gap set by SgNB. SgNB may notify MgNB of candidates for measurement gap settings that can be supported by SgNB in the frequency band division of the measurement gap set by MgNB. Such notification may be included, for example, in the signaling (e.g., positive response to SgNB addition request, positive response to SgNB modification request, etc.) notified from SgNB to MgNB. As a result, for example, the measurement gap can be flexibly set according to the communication situation between UE and MgNB, SgNB.

[0272] As another example, regarding which frequency band division between FR1 and FR2 is set by which base station among MgNB and SgNB, it may be determined by SgNB. SgNB may notify MgNB of information regarding the frequency band division of the measurement gap set by the MgNB. As a result, for example, the processing load at MgNB can be reduced.

[0273] The solutions in Embodiment 2 may be combined and used. For example, MgNB may determine the base station that determines the measurement gap for each frequency band division of FR1 and FR2 using the information on the subcarrier spacing used by both base stations. MgNB may obtain the information on the subcarrier spacing of SgNB using the RRC signaling notified from SgNB to UE via MgNB. As a result, for example, the measurement gap can be flexibly set in the communication system.

[0274] According to Embodiment 2, in NR-DC, since the measurement gaps for both FR1 and FR2 can be set independently, it is possible to prevent a decrease in the communication rate between the UE, MgNB, and SgNB.

[0275] Embodiment 3. In uplink transmission using a configured grant (see Section 10.3 of Non-Patent Document 16), an uplink with a low frequency provided to compensate for the difference in NR UL coverage, that is, a carrier of SUL (Supplementary UpLink; see Section 5.16 of Non-Patent Document 17) may be used, or a non-SUL carrier may be used. The base station may notify the UE of information indicating whether to use SUL / non-SUL in the signaling that notifies the UE of the configured grant. RRC signaling may be used for the notification. The above notification may be used in Type 1 of the configured grant. The UE may perform uplink transmission using the configured grant using the carrier indicated by the information included in the signaling.

[0276] The UE may perform uplink transmission using a dynamic grant using a carrier different from the carrier used for uplink transmission using the configured grant. The base station may notify the UE of an SUL / non-SUL switching instruction included in the dynamic grant.

[0277] In the above case, the following problem occurs. That is, a method for switching to a Type 1 configured grant across SUL / non-SUL is not disclosed. As a result, a discrepancy in the carrier used for UL transmission occurs between the UE and the base station, and as a result, a problem occurs in that the base station cannot receive the UL signal transmitted by the UE.

[0278] Figure 28 is a diagram for explaining the above problems. In the configured grant 3000 shown in Figure 28, the base station configures the UE to transmit the uplink signals 3005, 3006, and 3007 as type 1 of the configured grant. In the example shown in Figure 28, assume that SUL is configured as the carrier for transmitting the uplink transmissions 3005, 3006, and 3007. The UE transmits the uplink signals 3005 and 3006 using the SUL carrier according to the configured grant 3000.

[0279] In Figure 28, the base station transmits a dynamic grant 3010 to the UE. The dynamic grant 3010 contains information instructing the UE to transmit the uplink transmission 3015 on a non-SUL. The UE uses the dynamic grant 3010 to switch the uplink transmission carrier to non-SUL. Also, the UE uses the dynamic grant 3010 to transmit the uplink signal 3015 on non-SUL.

[0280] At the timing of transmitting the uplink signal 3007 shown in Figure 28, the uplink transmission carrier of the UE is non-SUL. Therefore, there is a conflict with the SUL which is the transmission carrier configured in the configured grant 3000, and as a result, the base station cannot receive the UL signal transmitted by the UE.

[0281] A method for solving the above problems is disclosed.

[0282] The base station transmits an SUL / non-SUL switching instruction for uplink transmission to the UE. The base station may transmit the instruction, for example, after transmitting the dynamic grant as described above. The UE is assumed to receive the instruction before the uplink transmission according to the configured grant. The UE uses the instruction to perform the switching between SUL and non-SUL.

[0283] The foregoing SUL / non-SUL switching instruction may be included in the DCI sent from the base station to the UE. The DCI may only include the foregoing SUL / non-SUL switching instruction. This makes it possible to reduce, for example, the amount of signaling from the base station to the UE. As another example, the DCI may include information related to the scheduling of uplink transmission, such as information related to frequency and / or time resources. The foregoing information related to scheduling may be the same as or different from the information included in the configured grant. The information included in the DCI may overwrite the information included in the configured grant. This makes it possible to perform flexible scheduling according to, for example, the status of the radio channel between the base station and the UE.

[0284] If the UE does not receive the instruction, it may not perform the SUL / non-SUL switching. In the foregoing case, the UE may not perform uplink transmission using the configured grant. For example, when the carrier is different between uplink transmission using dynamic grant and uplink transmission using the configured grant, the UE may not perform uplink transmission using the configured grant. This makes it possible for the UE to prevent unnecessary uplink transmission, and as a result, reduce the power consumption of the UE and enable flexible scheduling at the base station. As another example, when the carrier is the same between uplink transmission using dynamic grant and uplink transmission using the configured grant, the UE may perform uplink transmission using the configured grant. This makes it possible to reduce the signaling between the base station and the UE.

[0285] FIG. 29 is a diagram showing an operation of switching SUL / non-SUL using an SUL / non-SUL switching instruction before uplink transmission using a configured grant. In FIG. 29, the same elements as in FIG. 28 are denoted by the same reference numerals, and the common description is omitted.

[0286] In the downlink signal 3120 shown in FIG. 29, the base station instructs the UE to switch to the SUL. The UE uses the downlink signal 3120 to switch the uplink transmission carrier to the SUL. The UE uses the configured grant 3000 to transmit the uplink signal 3125 via the SUL.

[0287] Another solution is disclosed. The base station does not transmit an SUL / non-SUL switching instruction for uplink transmission using a configured grant to the UE. The UE switches between SUL and non-SUL without receiving the instruction before uplink transmission using the configured grant. This can reduce the amount of signaling between the base station and the UE, for example.

[0288] FIG. 30 is a diagram showing an operation of switching between SUL and non-SUL without using an SUL / non-SUL switching instruction before uplink transmission using a configured grant. In FIG. 30, the same elements as in FIG. 28 are denoted by the same numbers, and the common description is omitted.

[0289] After transmitting the uplink signal 3015, the UE performs a transmission carrier switching operation 3220 using the configured grant 3000. By this operation, the uplink transmission carrier of the UE is switched from non-SUL to SUL. The UE uses the configured grant 3000 to transmit the uplink signal 3225 via the SUL.

[0290] Another solution is disclosed. The base station and the UE may discard the configured grants after the aforementioned dynamic grant. The base station may reconfigure the configured grant in the uplink carrier used in the dynamic grant. This enables uplink transmission using a configured grant with a good channel state, for example, and as a result, improves the reliability of uplink transmission using the configured grant.

[0291] For example, in FIG. 28, the base station and the UE may discard the configured grant after the transmission and reception of the dynamic grant 3010. The UE may not perform uplink transmissions 3006 and 3007.

[0292] The base station may switch and use the method disclosed in Embodiment 3. The base station may notify the UE of information indicating which method among the methods disclosed in Embodiment 3 is to be used. For this notification, RRC signaling may be used, MAC signaling may be used, L1 / L2 signaling may be used, or a combination of the above-mentioned multiple types may be used. As a result, for example, the base station can communicate with UEs corresponding to different use cases simultaneously, and thus the number of UEs accommodated by the base station can be increased.

[0293] In Embodiment 3, the case where there is one SUL setting for the UE has been described, but multiple SUL settings may be performed. The multiple SULs may be, for example, SULs with different frequencies set. The same applies to the following embodiments and / or modification examples.

[0294] According to Embodiment 3, it is possible to prevent a mismatch of carriers used for UL transmission between the UE and the base station, and as a result, it is possible to prevent unnecessary uplink transmission from the UE.

[0295] Modification Example 1 of Embodiment 3. In uplink transmission using Configured Grant, in order to enable dynamic switching of the transmission carrier, Type 2 Configured Grant (see Section 10.3 of Non-Patent Document 16) may be used. The base station may include an SUL / non-SUL switching instruction in the DCI in Type 2 Configured Grant and notify the UE. The UE may use the DCI to switch the uplink carrier in Configured Grant between SUL and non-SUL.

[0296] In the foregoing case, the following problems occur. That is, unlike the configured grant of type 1, the configured grant of type 2 includes information on the uplink transmission resource, so the signaling size of the PDCCH increases. As a result, problems such as an increase in the overhead due to the PDCCH and / or a decrease in the reliability due to a decrease in the coding rate of the PDCCH occur.

[0297] A method for solving the foregoing problems is disclosed.

[0298] A new type of configured grant is provided (hereinafter, the configured grant of this type may be referred to as type 3). In the configured grant of type 3, it is possible to configure the uplink transmission resources in both SUL and non-SUL. The base station transmits information on the uplink transmission resource configured as the configured grant to the UE. The transmission of this information may be performed, for example, quasi-statically. As an example of quasi-static performance, RRC signaling may be used. In the transmission of this information, the information on the uplink transmission resource when using SUL and the information on the uplink transmission resource when using non-SUL may be included in the same signaling or in different signaling. The information on the uplink transmission resource described above may be the same as the information notified from the base station to the UE using RRC signaling in the configured grant of type 1.

[0299] The base station may include information for instructing the activation / deactivation of the configured grant in the DCI for the configured grant of type 3. The DCI may include only this information or may include other information. The information on the activation / deactivation of the configured grant using SUL and the information on the activation / deactivation of the configured grant using non-SUL may be included in the same DCI or in different DCIs. The UE may switch the uplink transmission carrier according to the configured grant using this instruction. Thereby, for example, the uplink transmission carrier in the configured grant of type 3 can be flexibly changed.

[0300] In the above, the information for instructing activation / deactivation of a configured grant may be information for simultaneously switching the activation / deactivation of the configured grant using SUL and the activation / deactivation of the configured grant using non-SUL. For example, using the fact that the information is activation, the UE may activate both the configured grant using SUL and the configured grant using non-SUL. In the above, the UE may use the UL carrier that it was using before transmitting the configured grant as it is. For example, in the transmission of a configured grant immediately after SUL is configured in a dynamic grant, the UE may use the SUL indicated in the immediately preceding dynamic grant. This can reduce, for example, the amount of signaling between the base station and the UE.

[0301] As another example, the base station may include a SUL / non-SUL switching instruction in the DCI for a type 3 configured grant. The DCI may include only the switching instruction or may include other information. The UE may use the instruction to switch the uplink transmission carrier. This can reduce, for example, the amount of signaling between the base station and the UE.

[0302] Another solution is disclosed. The UE may be allowed to configure type 1 and type 2 configured grants. For example, SUL scheduling may be configured using a type 1 configured grant, and non-SUL scheduling may be configured using a type 2 configured grant. In the above, both SUL and non-SUL scheduling may be configured using a type 2 configured grant. Regarding which of the type 1 and type 2 configured grants to use, for example, the activation / deactivation of the type 2 configured grant may be used, or a new identifier may be provided. This can avoid, for example, the need to implement a new type of configured grant, thus avoiding the complexity of the design in the communication system.

[0303] In the first modification example of Embodiment 3, the UE may not be allowed to set the configured grants of Type 1 and Type 2. This can reduce the processing load, for example, at the base station and the UE.

[0304] According to the first modification example of Embodiment 3, while enabling flexible switching between SUL / non-SUL in the configured grant, the signaling volume between the base station and the UE, particularly the signaling volume by PDCCH, can be reduced. Also, the switching between SUL / non-SUL in the configured grant can be executed quickly.

[0305] Second modification example of Embodiment 3. For the time resource in which the uplink transmission using non-SUL is scheduled by the configured grant, the uplink transmission using SUL by the dynamic grant may be scheduled. In the above, the dynamic grant may have priority over the configured grant. That is, the UE may perform the uplink transmission using SUL. For example, when the UE moves from the cell center to the cell edge, the data scheduled to be transmitted by the configured grant can be rescheduled for transmission by the dynamic grant using the dynamic grant. This can ensure reliability, for example, in communications where low latency is required. In the above, SUL and non-SUL may be reversed. The above-mentioned dynamic grant is different from the preemption shown in Embodiment 4 in that it does not generate a plurality of uplink transmission data.

[0306] When applying the foregoing method, the following problems occur. That is, when the UE prioritizes dynamic grants, an uplink carrier switch between SUL / non-SUL is required. A predetermined time is required for the uplink carrier switch. However, the base station does not know the required uplink carrier switch time for the UE. Also, it is not disclosed at what timing the uplink carrier switch is to be performed. As a result, for example, a deviation occurs between the timing when the UE actually transmits an uplink signal using SUL by a dynamic grant and the timing when the base station receives the uplink signal using SUL. As a result, there arises a problem that the reliability and communication rate of the uplink signal by the dynamic grant decrease.

[0307] A method for solving the foregoing problems is disclosed. The UE notifies information regarding the switching time between uplink carriers. As another method, the time may be predetermined in a standard or the like. In the foregoing notification and / or standard, the method disclosed in Embodiment 4 may be applied.

[0308] The UE stops the uplink transmission before the uplink carrier switch more than the switching time before the scheduling start timing by the dynamic grant. As another example, the UE may start the uplink transmission after the uplink carrier switch more than the switching time after the scheduling start timing by the dynamic grant, or the switching time may straddle before and after the scheduling start timing by the dynamic grant.

[0309] The foregoing uplink transmission stop may be performed by signaling (for example, DCI) from the base station to the UE. For example, the foregoing information regarding the uplink transmission stop may be included in the dynamic grant.

[0310] As another example in the foregoing uplink transmission stop, it may be predetermined as a standard regarding the operation of the UE. The UE may autonomously perform the uplink transmission stop for the switching time without signaling from the base station. As a result, for example, the amount of signaling from the base station to the UE can be reduced.

[0311] The above-described operation of stopping the uplink transmission may be applied at the timing of the end of scheduling by dynamic grant. For example, the UE may stop the uplink transmission for a time period longer than the switching time from the timing of the end of scheduling by dynamic grant.

[0312] Regarding the configured grant that prioritizes the dynamic grant in the second modification example 2 of the third embodiment, the transmission by scheduling using the configured grant may be stopped. The above-described stop period may be, for example, the scheduling in a period after a period overlapping with the dynamic grant, or the entire scheduling for one period overlapping with the dynamic grant, or the time resource after the timing when the overlap with the dynamic grant starts in the scheduling for one period overlapping with the dynamic grant, or only the time resource overlapping with the dynamic grant (for example, overlapping symbols). The above-described operation of stopping the transmission may be determined by the base station and notified to the UE, or may be statically determined in advance by the standard. The above-described notification may be performed quasi-statically using RRC signaling, or may be performed dynamically using MAC signaling and / or L1 / L2 signaling. As a result, for example, flexible scheduling at the base station becomes possible.

[0313] According to the second modification example 2 of the third embodiment, it is possible to ensure the reliability and communication rate in the uplink signal by the dynamic grant whose timing overlaps with the configured grant.

[0314] Embodiment 4. In order to reduce the power consumption of the UE and improve the reliability of uplink data transmission, it is being considered to perform uplink data transmission using a Supplemental UL (SUL), which is a UL carrier different from the UL carrier used when starting a connection. When SUL is set in the UE (in other words, when the gNB sets SUL), there may be data that requires low-latency characteristics. Even when SUL is set in the UE, a method for transmitting such data that requires low-latency characteristics with low latency is required. In Embodiment 4, a method for solving such problems is disclosed.

[0315] In NR, the following method of preferentially transmitting data that requires low-latency characteristics is being considered. It is a method that enables uplink data transmission that occurs later for a certain UE on the resources for which an uplink grant has already been given for uplink data transmission, either for the UE itself (intra-UE) or for another UE (inter-UE). This method is called preemption.

[0316] In order to solve the above problems, preemption is performed on a UE in which SUL is set (which may be referred to as an SUL-configured UE). Settings for preemption are made for the UE in which SUL is set. If SUL is set in the UE for which an uplink grant has occurred first, preemption settings are made for that UE. Or, if SUL is set in the UE for which an uplink grant will occur later, preemption settings are made for that UE. It may be possible to make preemption settings for either of the above-mentioned UEs.

[0317] Conventional preemption is performed in the case of a single UL carrier. However, by performing preemption on a UE in which SUL is set and multiple UL carriers can be used in this way, it becomes possible to transmit data that requires low-latency characteristics with low latency even when SUL is set in the UE.

[0318] Disclose a detailed method for performing preemption on a SUL-configured UE. Preemption may be performed on non-SUL for a SUL-configured UE. Also, preemption may be performed on SUL for a SUL-configured UE. Also, preemption may be performed when the timings of the resources of a previous uplink grant and a subsequent uplink grant overlap, rather than when the resources themselves overlap. The resource of an uplink grant is the resource on the frequency-time axis scheduled by the uplink grant.

[0319] Under the setting where the resource of the previous uplink grant is allocated on SUL and the resource of the subsequent uplink grant is allocated on non-SUL, preemption may be performed when the timings of the resources of the previous uplink grant and the subsequent uplink grant overlap. Also, under the setting where the resource of the previous uplink grant is allocated on non-SUL and the resource of the subsequent uplink grant is allocated on SUL, preemption may be performed when the timings of the resources of the previous uplink grant and the subsequent uplink grant overlap.

[0320] Thus, preemption may be performed when the timings of the resources allocated on SUL and the resources on non-SUL overlap. By doing so for a UE where simultaneous transmission on SUL and non-SUL is prohibited, preemption can be performed on the resources allocated to different UL carriers.

[0321] An uplink grant may be used for the uplink resource allocation to the UE that performs preemption. Whether the UE that performs preemption is in the intra-UE or inter-UE case, an uplink grant may be used for the uplink resource allocation of the data that occurs later for the UE. The gNB notifies the UE that performs preemption of an uplink grant. The UE that receives the uplink grant performs uplink transmission according to the uplink grant.

[0322] Notify the UE that has already had uplink resource allocation performed with an uplink grant to prioritize the transmission of subsequently generated data. For example, in the case of intra-UE, an uplink grant may be used for the notification. For example, in the case of inter-UE, an uplink grant may be used for the notification. Alternatively, a channel or signal may be provided separately to notify information regarding preemption. The channel or signal is referred to as PI (Preemption Indication). Thereby, the UE that has already had uplink resource allocation performed with an uplink grant can recognize to prioritize the transmission of subsequently generated data.

[0323] When prioritizing the transmission of subsequently generated data, the uplink transmission that has already had uplink resource allocation performed with an uplink grant may stop. Alternatively, it may be shifted to a later slot. Uplink transmission is performed in the shifted slot. By doing so, since the subsequently generated data and the already allocated data are not transmitted simultaneously, it becomes possible to avoid interference caused by the simultaneous transmission of both data. It becomes possible to improve the communication quality in the transmission of subsequently generated data.

[0324] FIGS. 31 and 32 are an example showing a preemption method in a UE where SUL is configured. The vertical axis indicates frequency, and the horizontal axis indicates time. The time axis direction is in slot units.

[0325] FIGS. 31 and 32 show the case of prioritizing the transmission of ultra-reliable low-latency service data (URLLC data) over enhanced mobile broadband service data (eMBB data) for which high-capacity communication is required. It is possible to transmit subsequently generated URLLC data using the resources for eMBB data that have been previously uplink granted. In other words, the resources for eMBB data that have been previously uplink granted are preempted as resources for subsequently generated URLLC data.

[0326] FIG. 31 shows an example of performing preemption on non-SUL for a SUL-configured UE. 4001 and 4002 indicate PDCCHs transmitted to the UE.

[0327] With PDCCH 4001, an uplink grant for eMBB data is transmitted from the gNB to the UE. Resource 4003 on non-SUL is allocated with the eMBB data grant.

[0328] The gNB determines to have the UE transmit, with priority given to later-occurring URLLC data, at the resource timing of the previously allocated resources. The gNB determines to have the UE transmit the URLLC data using the previously allocated resources on non-SUL.

[0329] The setting range of the number of slots from the UL grant to transmission may be made different between that for eMBB data and that for URLLC data. The minimum value or / and the maximum value of the number of slots may be made different between that for eMBB data and that for URLLC data. The setting range, or the maximum value or / and the minimum value, may be statically determined by a standard or the like. For example, the minimum value of the number of slots from the UL grant for URLLC data to transmission may be made smaller than the minimum value of the number of slots for eMBB data.

[0330] The processing time from UL grant reception to URLLC data transmission may be shorter for the URLLC data transmission UE than for the eMBB data transmission UE. In such a case, by making the minimum value of the number of slots from the UL grant for URLLC data to transmission smaller than the minimum value of the number of slots for eMBB data, it becomes possible to shorten the time from the UL grant to URLLC data transmission.

[0331] In the examples of this specification, the prioritized data is URLLC data and the data to be prioritized is eMBB data, but it is not limited to these data. For example, the prioritized data may be data that requires lower latency characteristics than the data to be prioritized. The gNB may determine the prioritized data and the data to be prioritized using the QoS required by the service, the QoS parameters, or the identifier of the QoS class (QCI, QoS Class Identifier).

[0332] The gNB sends a grant for URLLC data to the UE on the PDCCH 4002. The resources 4003 on non-SUL allocated earlier with the grant for URLLC data are allocated.

[0333] In addition, the gNB notifies the UE, on the PDCCH 4002, to preferentially transmit URLLC data on the resources 4003 on non-SUL allocated earlier. Alternatively, the gNB may notify the UE to stop transmitting eMBB data using the resources 4003 allocated earlier. Alternatively, the gNB may notify the UE to shift the transmission of eMBB data to a slot later than the resources 4003 allocated earlier. The UE shifts and transmits the eMBB data to a later slot 4004 on non-SUL. These information are referred to as information related to preemption. FIG. 31 shows shifting to a later slot.

[0334] Nine examples are shown below as information related to preemption.

[0335] (1) Information indicating to preferentially transmit URLLC data.

[0336] (2) Information indicating to stop transmitting eMBB data.

[0337] (3) Information indicating to shift and transmit eMBB data to a later slot.

[0338] Information indicating that eMBB data is shifted and transmitted to a previous slot.

[0339] (5) Shift amount.

[0340] (6) Scheduling information of the shift destination.

[0341] (7) Information indicating that eMBB data transmission is partially stopped.

[0342] (8) Information indicating that eMBB data and URLLC data are transmitted simultaneously.

[0343] (9) Combinations of (1) to (8).

[0344] (2) When used, gNB may notify UE of the scheduling of the eMBB data that has stopped transmission with a new UL grant. For example, when UE receives the information, it receives subsequent PDCCH dynamically. When UE receives a new UL grant, it transmits eMBB data according to the UL grant.

[0345] (3) When (3) and (4) are used, that is, when information indicating that eMBB data is shifted and transmitted is used, the information in (2) indicating transmission stop may be omitted.

[0346] In the foregoing, it is disclosed that eMBB data is shifted to a later slot, but eMBB data may be shifted to a previous slot. The information in (4) indicating that eMBB data is shifted and transmitted to a previous slot may be used. When the processing time from when UE receives the uplink grant or PI of PDCCH4002 until it transmits eMBB data is sufficient, by shifting eMBB data to a previous slot, the delay time until transmission can be reduced.

[0347] As the shift amount in (5), it may be information in the time axis direction. This information may be, for example, the time to shift, the number of slots to shift, or the number of TTIs to shift. For example, when shifting eMBB data backward, the shift amount may be represented as a positive number, and when shifting eMBB data forward, the shift amount may be represented as a negative number. Thereby, the information in (3) and (4) can be omitted.

[0348] As the scheduling information in (6), for example, there is resource information in the time axis direction, resource information in the frequency axis direction, etc. The resource information in the time axis direction may be represented in symbol units. The resource information in the frequency axis direction may be represented in sub - carrier units or resource block units. Among the scheduling information in (6), the same information as the scheduling information previously notified by the uplink grant may be omitted. Reduction of the amount of information can be achieved.

[0349] In the case of intra - UE, the gNB may include information regarding pre - emption in the UL grant for URLLC data and notify it. In the case of inter - UE, the gNB notifies the UE that previously transmitted the uplink grant for eMBB data of the information regarding pre - emption. The gNB may notify the UE with a UL grant or notify the UE with a PI.

[0350] In the case of inter - UE, PDCCH4002 may be composed of a PDCCH for URLLC data and a PDCCH or PI for pre - emption. Also, the PDCCH for URLLC data and the PDCCH or PI for pre - emption may be transmitted in different time - frequency resources.

[0351] By doing so, it becomes possible to transmit both URLLC data and eMBB data on non - SUL. Also, it becomes possible to transmit URLLC data with low latency.

[0352] FIG. 32 shows an example of performing preemption on SUL for a SUL-configured UE. 4101 and 4102 indicate PDCCHs transmitted to the UE.

[0353] With PDCCH 4101, an uplink grant for eMBB data is transmitted from the gNB to the UE. Information indicating transmission on SUL may be included in the uplink grant. Resource 4103 on SUL is allocated with the eMBB data grant.

[0354] The gNB determines to have the UE transmit, with priority given to later-occurring URLLC data, at the resource timing of the previously allocated resources. The gNB determines to have the UE transmit the URLLC data using the previously allocated resources on SUL.

[0355] With PDCCH 4102, the gNB transmits a grant for URLLC data to the UE. The previously allocated resource 4103 on SUL is allocated with the URLLC data grant.

[0356] Also, with PDCCH 4102, the gNB notifies the UE of information regarding preemption for the previously allocated resource 4103. FIG. 32 shows the case where the preemption information shifts the eMBB data transmission to a later slot than the previously allocated resource 4103. The UE shifts and transmits the eMBB data to a later slot 4104 on non-SUL.

[0357] By doing so, it becomes possible to transmit both URLLC data and eMBB data on SUL. Also, URLLC data can be transmitted with low latency.

[0358] Figures 33 and 34 are an example showing a preemption method in a UE where SUL is configured. Figures 33 and 34 show the case where preemption is performed when the timings of resources allocated on SUL and resources on non-SUL overlap.

[0359] Figure 33 shows a preemption method when the timings of resources for eMBB data on non-SUL granted earlier and resources for URLLC data on SUL granted later overlap. 4201 and 4202 indicate PDCCHs transmitted to the UE.

[0360] An uplink grant for eMBB data is transmitted from the gNB to the UE by PDCCH 4201. Resource 4203 on non-SUL is allocated with the eMBB data grant.

[0361] The gNB decides to let the UE transmit at the timing of the previously allocated non-SUL resource timing, giving priority to the subsequently generated URLLC data.

[0362] An uplink grant for URLLC data is transmitted from the gNB to the UE by PDCCH 4202. Resource 4205 on SUL is allocated at the timing of the previously allocated non-SUL resource with the URLLC data grant.

[0363] Also, the gNB notifies the UE by PDCCH 4202 of information regarding preemption for the previously allocated resource 4203. Figure 33 shows the case where the preemption information shifts the eMBB data transmission to a slot later than the previously allocated resource 4203. The UE shifts and transmits the eMBB data to the later slot 4204 on non-SUL.

[0364] By doing so, it becomes possible to transmit URLLC data on SUL and eMBB data on non-SUL. Also, it becomes possible to transmit URLLC data with low latency.

[0365] Figure 34 shows a preemption method when the timing of resources for eMBB data on SUL granted earlier and the resources for URLLC data on non-SUL granted later overlap. 4301 and 4302 indicate PDCCHs transmitted to the UE.

[0366] With PDCCH 4301, an uplink grant for eMBB data is transmitted from the gNB to the UE. Resource 4304 on SUL is allocated with the eMBB data grant.

[0367] The gNB determines to have the UE transmit, with priority given to the subsequently generated URLLC data, at the resource timing on SUL allocated earlier.

[0368] With PDCCH 4302, an uplink grant for URLLC data is transmitted from the gNB to the UE. Resource 4303 on non-SUL is allocated at the resource timing on SUL allocated earlier with the URLLC data grant.

[0369] Also, the gNB notifies the UE, with PDCCH 4202, of information regarding preemption for the previously allocated resource 4304. Figure 34 shows the case where the preemption information shifts the eMBB data transmission to a slot later than the previously allocated resource 4304. The UE shifts and transmits the eMBB data to the later slot 4305 on SUL.

[0370] By doing so, it becomes possible to transmit URLLC data on non-SUL and eMBB data on SUL. Also, it becomes possible to transmit URLLC data with low latency.

[0371] In the foregoing, the case where the numerology of SUL and non-SUL is the same has been disclosed, but it is not limited thereto. That is, the foregoing method can also be applied to the case where the numerology of SUL and non-SUL is different. The foregoing method can also be applied to the case where the numerology of the SUL BWP and the non-SUL BWP set for the UE is different.

[0372] Figures 35 to 38 are an example showing a preemption method in a UE in which SUL is set for the case where the numerology of SUL and non-SUL is different. The vertical axis represents frequency, and the horizontal axis represents time. The time axis direction is in slot units.

[0373] Figures 35 to 38 show, as an example, the case where non-SUL is operated in a high-frequency band and SUL is operated in a low-frequency band. Further, Figures 35 to 38 show the case where, as the numerology of each UL carrier, the SCS (sub-carrier spacing) of SUL is shorter and the slot length is longer than that of non-SUL. The case where the slot length of SUL is twice the slot length of non-SUL is shown.

[0374] Figure 35 shows an example of performing preemption on non-SUL for a UE with SUL set. The preemption method in Figure 35 is the same as that in Figure 31, so the description is omitted. Note that elements 4401 to 4404 in Figure 35 respectively correspond to elements 4001 to 4004 in Figure 31.

[0375] Figure 36 shows an example of performing preemption on SUL for a UE with SUL set. The preemption method in Figure 36 is the same as that in Figure 32, so the description is omitted. Note that elements 4501 to 4504 in Figure 36 respectively correspond to elements 4101 to 4104 in Figure 32.

[0376] Figures 37 and 38 are an example showing a preemption method in a UE where SUL is set. Figures 37 and 38 show the case where preemption is performed when the timings of resources allocated on SUL and resources on non-SUL overlap.

[0377] Figure 37 shows a preemption method when the timings of resources for eMBB data on non-SUL granted earlier and resources for URLLC data on SUL granted later overlap. The preemption method in Figure 37 is the same as that in Figure 33, so the description is omitted. Note that elements 4601 to 4605 in Figure 37 respectively correspond to elements 4201 to 4205 in Figure 33.

[0378] Figure 38 shows a preemption method when the timings of resources for eMBB data on SUL granted earlier and resources for URLLC data on non-SUL granted later overlap. The preemption method in Figure 38 is the same as that in Figure 34, so the description is omitted. Note that elements 4701 to 4705 in Figure 38 respectively correspond to elements 4301 to 4305 in Figure 34.

[0379] For example, as shown in the example of Figure 37, when the slot lengths of SUL and non-SUL are different, even if the eMBB data is shifted to a later slot for transmission, depending on the shift amount, there may still be a case where the resource timings overlap further. For example, this is the case when the shift amount of the resource 4603 of eMBB data in Figure 37 is one slot. In this case, even after the resource 4603 of eMBB data is shifted by one slot, it still overlaps with the timing of the resource 4605 of URLLC data.

[0380] As a method for solving such problems, it is advisable to limit the shift amount of eMBB data resources to a range that does not overlap with the resource timing of URLLC data. For example, in FIG. 37, the shift amount of the resource 4603 of eMBB data on non-SUL is set to 2 slots or more. The gNB may derive the shift amount using the grant of previous eMBB data and the grant of subsequent URLLC data so that the timings do not overlap even after the shift. The gNB may derive the shift amount considering the SCS of each UL carrier or the BWP of the UL carrier so that the timings do not overlap even after the shift.

[0381] By doing so, even when the slot lengths of SUL and non-SUL are different, it is possible to prevent the resource timing of eMBB data from overlapping with that of URLLC data, and preemption can be implemented for resources assigned to different UL carriers.

[0382] The above-described method discloses the case where the preempted data is shifted to a later slot. For example, in the example of FIG. 34, the resource 4304 for preempted eMBB data is shifted to the resource 4305, and eMBB data is transmitted at the resource 4305.

[0383] As another method, it is also possible to only stop the transmission without shifting the preempted data. As another method, it is also possible to partially stop the transmission. As another method, it is also possible to simultaneously transmit the preempted data with the data that preempts it.

[0384] A method of only stopping the transmission without shifting the preempted data is disclosed. The gNB sets transmission stop information as preemption information and transmits it to the UE. The UE that has received the transmission stop information stops the transmission at the preempted resource.

[0385] Figure 39 shows an example where only transmission stop is performed without shifting the preempted data. Figure 39 shows a preemption method when the timings of resources for eMBB data on the previously granted SUL and resources for URLLC data on the non-SUL granted later overlap. Since the method in Figure 39 is similar to that in Figure 34, mainly the different parts will be described.

[0386] The gNB notifies the UE, via PDCCH 4802, of information regarding preemption for the previously allocated resources 4804 on the SUL. The preemption information may be, for example, information indicating the stop of eMBB data transmission on the previously allocated resources 4804 on the SUL. The UE stops the transmission of eMBB data on the resources 4804 on the SUL.

[0387] The gNB may transmit an uplink grant for eMBB data to the UE again for the data whose transmission has been stopped. The gNB transmits an uplink grant to the UE as initial transmission data. As another method, the gNB may transmit an uplink grant to the UE as retransmission data. According to the uplink grant, the UE transmits the data whose transmission has been stopped. By doing so, when there is no resource to be shifted at the timing of notifying the preemption information or when the gNB cannot determine the resource to be shifted, etc., it becomes possible to stop the transmission of the preempted data to the UE. Thereby, it becomes possible to avoid interference with other uplink transmissions.

[0388] As another method, the preempted data may be partially stopped for transmission. When the timings of the resources for the preempted eMBB data and the resources for the preempting URLLC data overlap, the overlapping part may be stopped for transmission. The data at the overlapping timing may be punctured.

[0389] Figure 40 shows an example in which the data to be pre-empted is partially stopped from being transmitted. Figure 40 shows a pre-emption method when the timing of the resources for eMBB data on the previously granted SUL overlaps with the timing of the resources for URLLC data on the non-SUL granted later. Since the method in Figure 40 is similar to that in Figure 38, mainly the different parts will be described.

[0390] The gNB notifies the UE, via PDCCH 4902, of information regarding pre-emption for the previously allocated resources 4904 on the SUL. The pre-emption information may be, for example, information indicating a partial stop of eMBB data transmission on the previously allocated resources 4904 on the SUL. The UE stops the transmission of eMBB data at the timing that overlaps with the timing of URLLC data transmission on the resources 4904 on the SUL. The UE performs the transmission of eMBB data at the timing that does not overlap with the timing of URLLC data transmission.

[0391] By doing so, since it becomes possible to transmit eMBB data partially on the resource, the deliverability from the UE to the gNB will occur. It becomes possible to reduce the eMBB data transmission delay.

[0392] The data to be stopped from being transmitted may be in units of CBG (Code Block Group). The UE stops the CBG at the timing that overlaps with the timing of URLLC data transmission. The UE transmits the CBG at the non-overlapping timing. When the deliverability of each CBG is judged and retransmission is performed, the CBG received by the gNB does not need to be retransmitted, so it becomes possible to reduce the retransmission data. Also, for this reason, it becomes possible to reduce the eMBB data transmission delay.

[0393] The UE may transmit the data with transmission stopped at a timing of a resource that does not overlap with the timing of URLLC data transmission. The UE may transmit all the allocated eMBB data including the data with transmission stopped at a timing of a resource that does not overlap with the timing of URLLC data transmission. Since the resources on SUL allocated earlier for eMBB data transmission are fewer than resource 4904, the coding rate or MCS may be changed.

[0394] By doing so, it becomes possible to transmit all the eMBB data allocated by the resource, and thus it becomes possible to reduce the eMBB data transmission delay.

[0395] The gNB may notify the UE of the above-described partial transmission method. The partial transmission method may be notified in the previous eMBB grant, or may be notified together with the preemption information. As another method, the partial transmission method may be notified by RRC signaling, or may be notified by MAC signaling. Alternatively, the partial transmission method may be statically determined by a standard or the like. By doing so, both the gNB and the UE can recognize the partial transmission method. Therefore, it is possible to prevent malfunction due to a difference in recognition between the gNB and the UE.

[0396] A method of simultaneously transmitting the data to be preempted and the preempting data is disclosed. The gNB may set simultaneous transmission information as preemption information and transmit it to the UE. The UE that has received the simultaneous transmission information performs transmission on the preempted resource. For example, when the resources themselves overlap between the previous uplink grant and the subsequent uplink grant in one UE (intra-UE) or different UEs (inter-UE), the data allocated by the previous grant and the data allocated by the subsequent grant are simultaneously transmitted.

[0397] For example, in one UE (intra-UE), when the timing of the resources of the previous uplink grant overlaps with the timing of the resources of the subsequent uplink grant, the data allocated resources by the previous grant and the data allocated resources by the subsequent grant are transmitted simultaneously.

[0398] When transmitting simultaneously, the transmission power of the eMBB data granted earlier may be reduced, and the transmission power of the URLLC data granted later may be increased. The gNB may notify the UE of information regarding the transmission power during simultaneous transmission.

[0399] The information regarding the transmission power during simultaneous transmission may be the increase amount or decrease amount of the previous UL grant transmission power. Also, the information may be the increase amount or decrease amount of the transmission power from the subsequent UL grant.

[0400] For example, the gNB may notify the UE of the information regarding the transmission power of the eMBB data granted earlier together with the preemption information. For example, the gNB may notify the UE of the information regarding the transmission power of the URLLC data granted later by including it in the UL grant for the URLLC data.

[0401] As another method, the information regarding the transmission power during simultaneous transmission may be notified by RRC signaling, or may be notified by MAC signaling. Alternatively, the information may be statically determined by a standard or the like. By doing so, both the gNB and the UE can recognize the partial transmission method. Therefore, it is possible to prevent malfunction due to the recognition difference between the gNB and the UE.

[0402] It may be possible to select the foregoing methods of shifting, performing only transmission stop, performing partial transmission stop, and performing simultaneous transmission. These methods may be selectable according to conditions. For example, when switching between SUL and non-SUL is required, only transmission stop may be performed, and when switching between SUL and non-SUL is not required, partial transmission stop may be performed. By doing so, it is possible to avoid the complexity of control in the gNB and the UE in cases where the gNB or the UE cannot estimate the switching time. Therefore, it is possible to reduce malfunction.

[0403] Also, for example, if it is possible to make a transmission stop decision by the time until the first timing of performing pre-empted data transmission (transmission of eMBB data), only transmission stop may be performed, and if it is not possible, partial transmission stop may be performed. Also, for example, if it is not possible to make a partial transmission stop decision by the time until the first timing of performing partial transmission stop of pre-empted data transmission (transmission of eMBB data), simultaneous transmission may be performed.

[0404] The selection of these methods may be performed by the UE or by the gNB. The UE notifies the gNB of the capability information. When the gNB makes the selection, the gNB may select these methods using the UE's capability information. The gNB notifies the UE of the selected method. The method disclosed above may be applied to the notification method.

[0405] By doing so, it is possible to select the foregoing method according to the UE's capability, radio wave propagation environment, etc. Therefore, the UE can transmit eMBB data with higher reliability and lower latency.

[0406] When the UE switches between SUL and non-SUL for transmission, it may take a significant amount of time for this switch. For example, this is the case when the numerology of SUL is different from that of non-SUL. In a numerology with a long SCS and a short symbol interval, several symbols may be required for such a switch. If a significant amount of time is required for the switch, URLLC data or eMBB data cannot be transmitted during this switch time, leading to data loss. As a result, the communication quality will deteriorate.

[0407] A method for solving such problems is disclosed. Determine the data transmission time considering the switching time between SUL and non-SUL. Determine the resources for allocating data considering the switching time between SUL and non-SUL.

[0408] For example, the switch between SUL and non-SUL may be performed after or before the transmission of pre-emptible data (URLLC data) to be preferentially transmitted. The switching time may be considered during the transmission of pre-empted data (eMBB data). Considering the switching time in the resources for transmitting pre-empted data (eMBB data), it is preferable that the pre-empted data (eMBB data) is transmitted. Since the switch is not performed during the transmission of the pre-empting data, the data can be communicated with high reliability and low latency.

[0409] For example, in the case of FIG. 40, no switch is performed during the URLLC data transmission on the non-SUL resource 4903, and the switch from non-SUL to SUL is performed on the SUL resource 4905 to transmit eMBB data. The gNB may notify the UE of the resources for allocating eMBB data within the SUL resource 4905 by UL grant or preemption information considering the switching time. For example, when the switching time is two symbols, two symbols within the SUL resource 4905 are allocated for the switching time, and the symbols after excluding the two symbols within the resource 4905 are allocated for eMBB data.

[0410] The UE that receives the UL grant or preemption information transmits eMBB data on the resources allocated by the UL grant among the resources 4905 on SUL. The gNB schedules to be able to transmit eMBB data on the resources excluding the switching time, and notifies the scheduling information by the UL grant or preemption information.

[0411] By doing so, it is possible to eliminate data loss due to the switching between SUL and non-SUL when transmitting eMBB data. The data can be communicated with high reliability. Also, since URLLC data can be transmitted without being affected by the switching between SUL and non-SUL, the data can also be communicated with high reliability and low latency.

[0412] The switching time may be set individually for each UE, or the same time may be set for all UEs. When the same time is set for all UEs, the switching time may be statically determined by a standard or the like. Both the gNB and the UE can recognize the same determined switching time. The gNB can grant a UL grant to the UE in consideration of the switching time, and the UE can be designed to be able to perform switching within the switching time.

[0413] When the switching time is set individually for each UE, the gNB needs to recognize the switching time for each UE. A method for the gNB to recognize the switching time for each UE is disclosed. The UE includes information on the switching time between uplink carriers in the UE capability and notifies it. The UE may include information on the switching time between numerologies used for the uplink carrier in the UE capability and notify it.

[0414] The notification may be made when performing an RRC connection, or may be made in response to a request for UE capability or information on the switching time from the gNB to the UE. RRC signaling may be used for the notification. As another method, MAC signaling may be used. As another method, an L1 / L2 control signal may be used. It can be notified early.

[0415] The unit of the switching time may be a symbol unit. One symbol unit or a plurality of symbol units of an integer minute may be used as the unit of the switching time. Further, the range of the switching time is divided into one or more in advance, and numbers are assigned to each of the divided switching times. The number may be notified as information regarding the switching time. Reduction of the amount of information can be achieved.

[0416] By doing so, the gNB can recognize the switching time for each UE. For this reason, the gNB can determine the data transmission time in consideration of the switching time for each UE. Further, it becomes possible to determine the resource to which the data is allocated. High-reliability and low-latency communication can be achieved.

[0417] By adopting the method disclosed in the fourth embodiment, it is possible to obtain high-reliability and low-latency characteristics in the uplink communication. Further, by using SUL, it is possible to increase the available resources in the frequency axis direction, and thus communication with higher reliability than the conventional communication using only non-SUL is made possible. Further, by combining and using the above-described methods, flexible scheduling is made possible. For this reason, communication having even higher reliability and low-latency characteristics is made possible.

[0418] Modification Example 1 of the Fourth Embodiment In NR, a plurality of SCSs are used. Along with this, the SCS that can be transmitted may be restricted in the setting of the logical channel (Non-Patent Document 17). The gNB sets a list of one or more SCSs that permit transmission for each logical channel for the UE (Non-Patent Document 23). Hereinafter, the list is referred to as a permitted SCS list.

[0419] When SUL is set for the UE, switching occurs between a plurality of UL carriers. When the SCS of the logical channel of eMBB data or URLLC data is restricted, it may become impossible to switch between SUL and non-SUL with different numerologies. For example, when the SCS in the numerology of the BWP of the UL carrier to be switched to is not in the permitted SCS list, switching cannot be performed.

[0420] Disclose a method for solving such problems. For the UE for which SUL is set, the SCS restriction may also be set. The SCS restriction includes a setting that does not switch to a UL carrier different from the SCS in the permitted SCS list. The SCS restriction may include a setting that does not switch to the BWP of a UL carrier different from the SCS in the permitted SCS list.

[0421] When the gNB performs a UL carrier switch for the UE, the gNB performs the switch to the UL carrier in consideration of the SCS restriction set for the UE. When the gNB performs a UL carrier switch for the UE, the gNB performs the switch to a UL carrier having an SCS within the permitted SCS list set for the UE. One UL carrier may have multiple SCSs.

[0422] When the gNB performs a UL carrier BWP switch for the UE, the gNB performs the switch to the UL carrier BWP in consideration of the SCS restriction set for the UE. When the gNB performs a UL carrier switch for the UE, the gNB performs the switch to the BWP of a UL carrier having an SCS within the permitted SCS list set for the UE.

[0423] As another method, when the gNB sets SUL for the UE, the gNB may set SUL having an SCS within the permitted SCS list set for the UE. When the gNB sets SUL for the UE, the gNB may set SUL having a BWP having an SCS within the permitted SCS list set for the UE.

[0424] As another method, the gNB may include the SCS of the SUL set for the UE in the permitted SCS list of the UE. The gNB may include the SCS of the BWP of the SUL set for the UE in the permitted SCS list of the UE.

[0425] The SCS of the SUL configured by the gNB for the UE may be automatically incorporated into the UE's permitted SCS list. When the gNB configures the BWP of the SUL for the UE, the SCS of the BWP of the SUL may be automatically incorporated into the UE's permitted SCS list. The gNB may not separately configure the SCS to the UE's permitted SCS list.

[0426] Another method for solving the foregoing problem is disclosed. For the UE that configures the SUL, the configuration of the permitted SCS list is not performed. The gNB does not perform the configuration of the permitted SCS list for the UE that configures the SUL. The gNB may cancel the configuration of the permitted SCS list for the UE that configures the SUL. The gNB may perform a setting to remove the SCS in the permitted SCS list for the UE that configures the SUL.

[0427] Another method for solving the foregoing problem is disclosed. For the UE that configures the SUL, the SCS restriction is not applied. The gNB may configure the SUL having an SCS not in the permitted SCS list for the UE. The gNB may configure the BWP of the SUL having an SCS not in the permitted SCS list for the UE.

[0428] In the SUL, it may be permitted to map to a resource having an SCS not in the permitted SCS list. In the SUL, it may be permitted to map to a BWP having an SCS not in the permitted SCS list.

[0429] Another method for solving the foregoing problem is disclosed. SCS restrictions for non-SUL and SCS restrictions for SUL are provided. The conventional SCS restriction may be the SCS restriction for non-SUL. In addition to the conventional SCS restriction, an SCS restriction for SUL is provided. When there are multiple SULs, in addition to the conventional SCS restriction, multiple SCS restrictions may be provided. SCS restrictions may be provided for each UL carrier or for each UL carrier group including one or more UL carriers. The foregoing method may be appropriately applied to the SCS restriction for each UL carrier.

[0430] By doing so, it becomes possible to set an SCS restriction different from the conventional SCS restriction for SUL. For example, in SUL, there may be no SCS restriction. Transmission on SUL is possible for any logical channel.

[0431] By doing so, when SUL is set for the UE, the SCS of the logical channel of eMBB data or URLLC data enables switching between SUL and non-SUL even if it is restricted on non-SUL. Data transmission on SUL can be flexibly set, and it becomes possible to improve communication quality.

[0432] In the foregoing, a method for a UE with SUL set or a UE to which SUL is to be set has been disclosed, but the foregoing method may be limited to the case of preemption. The foregoing method may be limited to the case of performing preemption on a UE with SUL set. For example, when preemption is performed on a UE with SUL set, do not switch to a UL carrier different from the SCS in the permitted SCS list. For example, when preemption is performed on a UE with SUL set, do not apply the SCS restriction, etc.

[0433] In the case of preemption, particularly low-latency characteristics are required. Also, as disclosed in Embodiment 4, communication quality can be improved by switching the UL carrier in preemption. Therefore, particularly in preemption, by applying the operation method of the permitted SCS list as disclosed in Modified Example 1 of Embodiment 4, it becomes possible to obtain high-reliability and low-latency characteristics.

[0434] Modified Example 2 of Embodiment 4. In Embodiment 4, the case where preempted data is shifted to a later slot or a previous slot has been disclosed. A method of performing such a shift on the same carrier as the UL carrier to which the resource previously UL-granted is mapped has been disclosed. Here, another method is disclosed.

[0435] When giving priority to transmitting later-generated data, data for which uplink resource allocation has already been performed with a previous uplink grant is shifted and transmitted to a later or earlier slot on SUL or non-SUL. The data may be shifted to a slot on a UL carrier different from the UL carrier on which uplink resource allocation was performed with the previous uplink grant.

[0436] Provide UL carrier information of the shift destination. The gNB notifies the UL carrier information of the shift destination to the UE that transmits pre-empted data (for example, eMBB data). The UL carrier information of the shift destination may be included in the pre-emption information. The gNB notifies the pre-emption information to the UE that transmits pre-empted data by means of a UL grant or PI. When shifting to a slot on the same UL carrier as the UL carrier on which uplink resource allocation was performed with the previous uplink grant, the UL carrier information of the shift destination may be omitted.

[0437] The gNB may notify the UE that transmits pre-empted data of the BWP information on the UL carrier of the shift destination. The BWP information may be notified included in the pre-emption information. As the UL carrier information of the shift destination, a SUL / non-SUL indicator (Non-Patent Document 18), which is information indicating whether it is SUL or non-SUL, may be used.

[0438] By doing so, it becomes possible to transmit pre-empted data by switching the UL carrier. For example, when the communication quality between non-SUL and SUL changes over time, the gNB may set the UL carrier with better communication quality as the UL carrier of the shift destination. As a result, it becomes possible to transmit pre-empted data on the UL carrier with better communication quality. Therefore, it becomes possible to obtain higher reliability for the pre-empted data that was previously UL granted.

[0439] For example, when wide coverage is required, transmission may be performed on SUL. The gNB may set SUL as the UL carrier to be shifted to for UEs with poor communication quality on non-SUL. This enables the preempted data to be transmitted with better communication quality.

[0440] For example, transmission may be performed on a UL carrier with low resource usage load. When the resource usage load of non-SUL resources is high, the gNB may set SUL as the UL carrier to be shifted to. This enables more resources to be allocated to the preempted data at an earlier timing. Therefore, transmission can be performed with low latency.

[0441] FIG. 41 is an example showing a method of shifting and transmitting data for which resource allocation has been performed in a previous uplink grant to a slot on a UL carrier different from the UL carrier by preemption. FIG. 41 shows a preemption method when resources of eMBB data on non-SUL granted previously and resources of URLLC data on non-SUL granted later overlap. Since the method of FIG. 41 is the same as that of FIG. 31, mainly different parts will be described.

[0442] The gNB transmits an uplink grant for eMBB data to the UE using PDCCH 5001. For example, assume that the location of the UE at this time is within the coverage of non-SUL. In this case, the gNB allocates resource 5003 on non-SUL to the UE.

[0443] The gNB decides to let the UE transmit the subsequently generated URLLC data preferentially at the resource timing of the previously allocated resources. For example, assume that the location of the UE at this time is within the coverage of non-SUL. In this case, the gNB decides to let the UE transmit the URLLC data using the previously allocated resources on non-SUL. A grant for URLLC data is transmitted from the gNB to the UE via PDCCH5002. The previously allocated resources 5003 on non-SUL are allocated by the grant for URLLC data.

[0444] For example, assume that the UE that previously transmitted a UL grant is moving within the coverage of SUL while at the edge or outside the coverage of non-SUL. In this case, the gNB notifies the UE that previously transmitted a UL grant, via PDCCH5002, to shift the previously allocated resources 5003 on non-SUL to a later slot 5004 on SUL. It is advisable to notify by setting SUL as the UL carrier information of the shift destination. The UL carrier information of the shift destination may also be included in the preemption information for notification.

[0445] The UE shifts and transmits the eMBB data to a later slot 5004 on SUL.

[0446] By doing so, it becomes possible to let the UE that has moved within the coverage of SUL while at the edge or outside the coverage of non-SUL transmit the eMBB data using the resources on SUL. Therefore, it becomes possible to improve the communication quality of the preempted data.

[0447] FIG. 42 shows an example of a method of shifting and transmitting data in which resource allocation is performed in the previous uplink grant to a slot on a UL carrier different from the UL carrier by preemption. FIG. 42 shows a preemption method when the resource timings of eMBB data resources on non-SUL granted previously and URLLC data resources on SUL granted later overlap. Since the method of FIG. 42 is the same as that of FIG. 33, mainly different parts will be described.

[0448] The gNB transmits an uplink grant for eMBB data to the UE by PDCCH 5101. For example, when the UL communication quality at this time is better on non-SUL than on SUL, the gNB allocates resource 5103 on non-SUL to the UE.

[0449] The gNB determines to give priority to the subsequently generated URLLC data and cause the UE to transmit at the resource timing allocated previously. For example, when the UL communication quality at this time is better on SUL than on non-SUL, the gNB determines to cause the UE to transmit the URLLC data using resources on SUL.

[0450] A grant for URLLC data is transmitted from the gNB to the UE by PDCCH 5102. Resource 5105 on SUL is allocated by the grant for URLLC data.

[0451] In addition, the gNB notifies the UE that has previously received the UL grant that the resource 5103 on non-SUL allocated previously is shifted to the subsequent slot 5104 on SUL by PDCCH 5102. It is preferable to notify by setting SUL as the UL carrier information of the shift destination. The UL carrier information of the shift destination may be included in the preemption information and notified.

[0452] The UE shifts and transmits the eMBB data to the subsequent slot 5104 on SUL.

[0453] In the foregoing example, a shift to a later slot was disclosed, but a shift to an earlier slot may also be possible.

[0454] By doing so, it becomes possible to select the UL carrier to which the preempted data is shifted according to the radio wave propagation situation, the location of the UE, the load situation on each UL carrier, etc. It becomes possible to transmit the preempted data on a UL carrier with better communication quality. Also, since the UE can transmit the preempted data with lower transmission power, power consumption of the UE can be reduced.

[0455] A UL carrier switching request may be provided. The UE notifies the gNB of a UL carrier switching request. The UL carrier switching request may include information indicating the requested UL carrier. When the SUL is at a low frequency, it may be possible to reduce the power consumption of the UE by transmitting UL data on the SUL. For example, when the remaining battery level of the UE becomes low, it is possible to reduce the power consumption of the UE and extend the communication time by transmitting UL data on the SUL.

[0456] Also, when the UE estimates the UL communication quality from the DL communication quality and requests a switch to a UL carrier with good communication quality, the UE notifies the gNB of a UL carrier switching request.

[0457] When the UE requests a switch to the SUL, the UE notifies the gNB by including information indicating the SUL in the UL switching request. The gNB that has received the request may instruct the UE to transmit UL data on the SUL with a UL grant. Alternatively, it may instruct the transmission of UL data on the SUL for preempted eMBB data transmission.

[0458] By doing so, power consumption of the UE can be reduced. Also, it becomes possible to improve the communication quality of UL data.

[0459] Modification Example 3 of Embodiment 4. In Modification Example 2 of Embodiment 4, a method that enables setting of a UL carrier to which data to be preempted is shifted in the case of shifting to a later slot was disclosed. Here, a method that enables setting of a UL carrier without shifting is disclosed.

[0460] When giving priority to data generated later and transmitting it, data for which uplink resource allocation has already been performed with a previous uplink grant is transmitted by switching the UL carrier. Switch the UL carrier in which uplink resource allocation has been performed with the previous uplink grant to a different UL carrier.

[0461] Provide UL carrier switching information. The gNB notifies the UE that transmits preempted data (for example, eMBB data) of the UL carrier switching information. The UL carrier switching information may be included in the preemption information. The gNB notifies the UE that transmits preempted data of the preemption information with a UL grant or a PI.

[0462] The gNB may notify the UE that transmits preempted data of the BWP information on the switched UL carrier. The BWP information may be included in the preemption information and notified. As the UL carrier switching information, a SUL / non-SUL indicator (Non-Patent Document 18), which is information indicating whether it is SUL or non-SUL, may be used.

[0463] By doing so, it becomes possible to transmit the preempted data by switching the UL carrier without shifting. For example, in a case where the communication quality between non-SUL and SUL changes over time, the gNB may switch to a UL carrier with better communication quality. As a result, it becomes possible to transmit the preempted data on a UL carrier with better communication quality. Therefore, it becomes possible to obtain higher reliability for the preempted data that has been previously UL granted.

[0464] Similar to Modification Example 2 of Embodiment 4, for example, when wide coverage is required, it may be switched to SUL, or for example, to a UL carrier with a low resource usage load. The preempted data can be transmitted with better communication quality or with lower latency.

[0465] FIG. 43 is an example showing a method of transmitting data for which resource allocation has been performed in the previous uplink grant in a slot on a UL carrier different from the UL carrier by preemption. FIG. 43 shows a preemption method when resources for eMBB data on non-SUL granted previously and resources for URLLC data on non-SUL granted later overlap.

[0466] The gNB transmits an uplink grant for eMBB data to the UE by PDCCH 5201. For example, assume that the location of the UE at this time is within the non-SUL coverage. In this case, the gNB allocates resource 5203 on non-SUL to the UE.

[0467] The gNB determines to cause the UE to transmit the subsequently generated URLLC data preferentially at the resource timing allocated previously. For example, assume that the location of the UE at this time is within the non-SUL coverage. In this case, the gNB determines to cause the UE to transmit the URLLC data using the non-SUL resources allocated previously. A grant for URLLC data is transmitted from the gNB to the UE by PDCCH 5202. The non-SUL resource 5203 allocated previously is allocated by the grant for URLLC data.

[0468] For example, assume that at this time, the UE that previously transmitted a UL grant moves from the coverage edge or outside the coverage of non-SUL to within the coverage of SUL. In this case, the gNB notifies the UE that previously transmitted a UL grant, via PDCCH 5202, to switch the previously allocated resources 5203 on non-SUL to slot 5204 on SUL. It is advisable to notify by setting SUL as UL carrier switching information. The UL carrier information may also be included in the preemption information for notification.

[0469] The UE switches the eMBB data to the subsequent slot 5204 on SUL for transmission.

[0470] By doing so, it becomes possible to cause the UE that has moved from the coverage edge or outside the coverage of non-SUL to within the coverage of SUL to transmit eMBB data using the resources on SUL. Therefore, it becomes possible to improve the communication quality of the preempted data. Also, by switching without shifting, it becomes possible to reduce the delay time until the transmission of the preempted data.

[0471] FIG. 44 is a diagram showing a case where SUL and non-SUL have different SCSs. FIG. 44 is an example showing a method of transmitting data for which resource allocation has been performed in a previous uplink grant in a slot on a UL carrier different from the UL carrier by preemption. FIG. 44 shows a preemption method when the resources for eMBB data on non-SUL granted previously and the resources for URLLC data on non-SUL granted later overlap.

[0472] The gNB transmits an uplink grant for eMBB data to the UE via PDCCH 5301. For example, assume that the location of the UE at this time is within the coverage of non-SUL. In this case, the gNB allocates resources 5303 on non-SUL to the UE.

[0473] The gNB determines to make the UE transmit the subsequently generated URLLC data preferentially at the resource timing of the previously allocated resources. For example, assume that the location of the UE at this time is within the coverage of non-SUL. In this case, the gNB determines to make the UE transmit the URLLC data using the previously allocated resources on non-SUL. A grant for URLLC data is transmitted from the gNB to the UE on PDCCH 5302. The previously allocated resources 5303 on non-SUL are allocated in the grant for URLLC data.

[0474] For example, assume that the UE that previously transmitted a UL grant moves to within the coverage of SUL at the edge or outside the coverage of non-SUL at this time. In this case, the gNB notifies the UE that previously transmitted a UL grant to switch the previously allocated resources 5303 on non-SUL to SUL on PDCCH 5302. It is advisable to notify by setting SUL as UL carrier switching information. It is also possible to notify by including UL carrier information in the preemption information.

[0475] In the case of switching to a UL carrier with a different SCS, there is a possibility of switching to slot 5304 with only the UL carrier switching information. In the scheduling when the conventional DL and UL SCSs in NR are different, the slot allocated by the previous UL grant for eMBB data is determined by the number of slots for the SCS of the allocated UL carrier or the BWP of the UL carrier.

[0476] Therefore, in FIG. 44, assume that in the previous UL grant 5301 for eMBB data, the slot 5303 five slots after on non-SUL is allocated. Also, assume that in PDCCH 5302, only UL carrier switching information is notified to switch the previously allocated resource 5303 on non-SUL to SUL. In such a case, the UE will allocate the slot 5304 five slots after on SUL from the uplink slot at the timing of the previous UL grant 5301 for eMBB data.

[0477] Therefore, the UE switches and transmits the eMBB data to the subsequent slot 5304 on SUL.

[0478] By doing so, it becomes possible to improve the communication quality of the preempted data by switching the UL carrier. However, if the switch is made without shifting, the delay time until the transmission of the preempted data cannot be reduced.

[0479] Disclose a method for reducing the delay time until the transmission of the preempted data when the switch is made without shifting.

[0480] Provide offset amount information in the time axis direction with respect to the number of slots granted before the notification of the UL carrier switching information. The offset amount may be in slot units. For example, if the number of slots in the previous grant is K1 and the offset amount is K2, the newly set slot may be the (K2 + K1)-th slot from the previous grant timing.

[0481] By notifying such an offset amount in this way, it becomes possible to change the number of slots granted previously. For example, assume that the number of slots in the previous grant is 5 and the offset amount set together with the UL carrier switching information is -3. In this case, the newly set slot will be 5 + (-3) = 2. A new slot is set as the second slot from the previous grant timing.

[0482] FIG. 45 is a diagram showing a case where the SUL and the non-SUL have different SCSs. FIG. 45 is a diagram showing an example of a case where the UL carrier is switched by setting an offset amount. Since FIG. 45 is the same as FIG. 44, mainly different parts will be described.

[0483] The gNB notifies, by PDCCH 5402, the UE that has previously transmitted a UL grant to switch the resource 5403 on the non-SUL allocated previously to the SUL. It is preferable to notify by setting the SUL as UL carrier switching information. The offset information is notified together with the UL carrier information. Here, it is notified by setting to return 3 slots (-3) as the offset information. The UL carrier information and the offset information may be included in the preemption information and notified.

[0484] By doing so, the slot after the UL carrier is switched to the SUL becomes the second slot in the SCS of the SUL from the timing of the previous UL grant 5401. Therefore, slot 5404 is set in FIG. 45.

[0485] Therefore, the UE switches the eMBB data to slot 5404 on the SUL and transmits it.

[0486] By doing so, when the UL carrier is switched between UL carriers having different SCSs, it is possible to improve the communication quality of the preempted data and to reduce the delay time until the preempted data transmission.

[0487] Upon receiving the UL carrier switching information, the number of slots granted prior to the notification may be reset. Resetting can be statically determined in advance by standards or the like, making it recognizable to both the gNB and the UE. The gNB may notify the UE that previously received a UL grant of the new slot information. The newly set slot information may be included in the preemption information. The slot information may be the shift amount of the slot from the notification timing of the preemption information. The slot information may also be the shift amount of the slot from the PI.

[0488] By doing so, it becomes possible to newly set the slots after switching to a UL carrier with a different numerology without using the slots set by the previous UL grant. Therefore, for example, it becomes possible to easily set the slots at the same timing as the preempted slot.

[0489] When switching the UL carrier, it may be possible to reset the slot setting and switch only at the same timing as the preempted slot. Problems occur when switching to a UL carrier with a different SCS. For example, when switching from a UL carrier with a long SCS to a UL carrier with a short SCS, a single long SCS slot will contain multiple short SCS slots. It becomes impossible to identify the slot at the same timing as the preempted slot.

[0490] A method for solving such problems is disclosed. Switch to a predetermined short SCS slot within the long SCS slot. The predetermined slot may be, for example, the first slot. Alternatively, it may be the last slot. The predetermined slot may be statically determined in advance by standards or the like. It becomes commonly recognizable to both the gNB and the UE, reducing the risk of malfunction.

[0491] Alternatively, the gNB may notify the UE of a predetermined slot. The number of slots of the short SCS offset within one slot of the long SCS may be notified. The offset value from the start may be set and notified. As a notification method, the predetermined slot may be notified in advance by RRC signaling. Also, the notification may be made by MAC signaling. Malfunctions can be reduced. Also, the notification may be made by L1 / L2 control signaling. It can be set dynamically as appropriate.

[0492] FIG. 46 is a diagram showing a case where the SUL and the non-SUL have different SCSs. FIG. 46 is a diagram showing an example of a case where the UL carrier is switched by setting the reset and the shift amount from the PI. Since FIG. 46 is the same as FIG. 45, mainly different parts will be described.

[0493] The gNB notifies the UE that has previously received the UL grant, via PDCCH 5502, to switch the resource 5503 on the non-SUL allocated previously to the SUL. It is preferable to notify by setting the SUL as UL carrier switching information. The shift amount from the PI at the UL carrier is notified together with the UL carrier information. The shift amount may be in units of slots. In the example of FIG. 46, it is one slot.

[0494] The UE switches the UL carrier to the SUL and resets the setting of the slot received by the previous UL grant, which is four slots in the example of FIG. 46. Also, the UE shifts one slot from the PI on the SUL and transmits eMBB data on the resource 5504 on the SUL.

[0495] By doing so, when the UL carrier is switched between UL carriers having different SCSs, transmission can be performed at the same timing. It is possible to reduce the delay time until the data transmission to be preempted.

[0496] By appropriately combining the methods disclosed in Embodiment 4 to Modification Example 3 of Embodiment 4, flexible settings can be made for the preempted data. For this reason, it becomes possible to improve communication quality and reduce delay time.

[0497] Modification Example 4 of Embodiment 4. Disclose a preemption method when a configured grant is set for the UE with SUL or non-SUL.

[0498] Perform preemption at the resources or resource timing allocated by the configured grant. Whether there is an uplink transmission with the configured grant may or may not be present. Regardless of whether there is an uplink transmission with the configured grant, perform preemption at the resources or resource timing allocated by the configured grant.

[0499] As a method of the configured grant, there is a method of notifying the UE of the scheduling information given as a grant only by RRC signaling (referred to as Type 1 here). As another method, there is a method of including a part of the scheduling information given as a grant in DCI and notifying the UE by PDCCH, and notifying the UE of the other part by RRC signaling (referred to as Type 2 here). As the information included in DCI and notified, there is at least activation / deactivation information and resource allocation information in the frequency axis direction.

[0500] Also, in Modification Example 1 of Embodiment 3, as another method of the configured grant, a method of including activation / deactivation information of the scheduling information given as a grant in DCI and notifying the UE by PDCCH, and notifying the UE of the other information by RRC signaling was disclosed. Here, this is referred to as Type 3.

[0501] Pre - emption may be performed in Type 1. Also, pre - emption may be performed during the activation to de - activation of Type 2 and Type 3. As a pre - emption method, the methods disclosed from Embodiment 4 to Modification Example 3 of Embodiment 4 may be appropriately applied. It is advisable to apply those methods after changing the previous UL grant to a configured grant.

[0502] When a UL transmission occurs at the UE according to the resources or resource timing assigned by the configured grant, the UE may perform transmission stop, shift of the transmission slot, switching of the transmission UL carrier, etc. In the case of transmission stop, the data for which transmission has stopped may be transmitted using the resources assigned by the next configured grant.

[0503] Also, when there is no indication of a shift of the transmission slot, transmission may be performed using the resources assigned by the next configured grant. Since resources for UL transmission are periodically assigned in the configured grant, the resources can be made available. It becomes possible to facilitate the control of pre - emption.

[0504] To perform the switching of the transmission UL carrier, it is advisable to enable the transmission of pre - empted UL data on a UL carrier different from the UL carrier on which the configured grant is set. By doing so, it becomes possible to use multiple UL carriers for UL transmission for a UE with SUL set, so flexible scheduling becomes possible. Effects such as improvement of low - latency characteristics, improvement of reliability, reduction of UE power consumption, and improvement of coverage can be obtained.

[0505] For a UE with SUL set, the configured grant may be set so that the resource timings overlap on multiple UL carriers. This makes it easier to switch UL carriers and aims to improve low - latency characteristics.

[0506] Between activation and deactivation of Type 2 and Type 3, in other words, except during activation or during deactivation, since the resources scheduled by the configured grant are not valid, it is not necessary to reserve the resources. Therefore, the same processing as when no configured grant has been made may be applied.

[0507] Figure 47 is an example showing a method of preemption when a configured grant is set. A configured grant is set on non-SUL for eMBB data.

[0508] Resources 5602, 5603, and 5605 for eMBB data are periodically allocated with a configured grant. A grant for URLLC data is transmitted from the gNB to the UE on PDCCH 5601. With the grant for URLLC data, resource 5603 on non-SUL previously allocated with the configured grant is allocated.

[0509] Also, the gNB notifies the UE to preferentially transmit URLLC data on resource 5603 on non-SUL previously allocated with the configured grant on PDCCH 5601. Also, the gNB may notify the UE to shift resource 5603 previously allocated with the configured grant to a later slot 5604. Preemption information may be applied as this information. If eMBB data occurs in the UE, it is transmitted in a later slot 5604 on non-SUL.

[0510] Figure 48 is an example showing a method of preemption when a configured grant is set. A configured grant is set on SUL for eMBB data. Figure 48 shows the case where the numerology of non-SUL and SUL is different.

[0511] Resources 5702, 5704, and 5706 for eMBB data are periodically allocated with a configured grant. A grant for URLLC data is transmitted from the gNB to the UE on PDCCH 5701. With the grant for URLLC data, a resource 5703 in a slot of a different UL carrier, whose timing overlaps with that of the resource 5704 on SUL allocated previously with the configured grant, is allocated.

[0512] The gNB notifies the UE to preferentially transmit URLLC data on PDCCH 5701 at the timing of the resource 5704 on SUL allocated previously with the configured grant. Also, the gNB may notify the UE to shift the resource 5704 allocated previously with the configured grant to a later slot 5705. Such preemption information may be applied as this information. If eMBB data occurs in the UE, it is transmitted in a later slot 5705 on SUL.

[0513] Figure 49 is an example showing a method of preemption when a configured grant is set. A configured grant is set on non-SUL for eMBB data. Since Figure 49 is similar to Figure 47, mainly different parts will be described.

[0514] In the example of Figure 47, instead of the preempted resource 5603, a resource 5604 in a later slot was allocated. In Figure 49, instead of the preempted resource 5803, a resource 5805 in a slot of a different UL carrier is allocated. If eMBB data occurs in the UE, the UL carrier is switched and transmitted in the slot 5805 on SUL. Note that elements 5801, 5802, and 5804 in Figure 49 respectively correspond to elements 5601, 5602, and 5605 in Figure 47.

[0515] FIG. 50 is an example showing a method of preemption when a configured grant is set. A configured grant is set on SUL for eMBB data. Since FIG. 50 is the same as FIG. 48, mainly different parts will be described.

[0516] In the example of FIG. 48, instead of the preempted resource 5704, the resource 5705 in the later slot was allocated. In FIG. 50, instead of the preempted resource 5905, the resource 5904 in the slot of a different UL carrier is allocated. If eMBB data occurs in the UE, the UL carrier is switched and transmitted in the non-SUL slot 5904. Note that the elements 5901, 5902, 5903, 5906 in FIG. 50 respectively correspond to the elements 5701, 5702, 5703, 5706 in FIG. 48.

[0517] By doing so, even when a configured grant is set for eMBB data, it is possible to give priority to transmitting URLLC data. URLLC data can be transmitted with low latency.

[0518] Preemption may also be performed even when a configured grant is set for URLLC data. As a preemption method, the methods disclosed in Embodiment 4 to Modification Example 3 of Embodiment 4 may be appropriately applied.

[0519] FIG. 51 is an example showing a method of preemption when a configured grant is set. A configured grant is set on non-SUL for URLLC data.

[0520] The resources 6002, 6003, 6004 for URLLC data are periodically allocated with a configured grant. A grant for eMBB data is transmitted from the gNB to the UE by PDCCH 6001. Before the resource 6005 on SUL allocated by the grant for eMBB data, URLLC data occurs.

[0521] In the case of intra-UE, the UE determines to give priority to transmitting URLLC data that occurs later. It may be statically determined in the standard or the like that data of services requiring low-latency characteristics may be preferentially transmitted. Alternatively, the gNB may notify the UE of the priority order of the data. The gNB may set the logical channel priority as the priority order of the data for the UE. The logical channel priority may be determined using, for example, the QoS required by the service, QoS parameters, or QCI.

[0522] Here, the case of giving priority to transmitting URLLC data that occurs later is shown. The uplink transmission for which uplink resource allocation has already been performed with an uplink grant is shifted to a later slot for implementation. It is advisable to determine in advance the transmission method of the data preempted in this way, such as whether to shift, stop, or switch.

[0523] The priority order of the service, the priority order of the data, the transmission method of the preempted data, or the resource information for the transmission may be statically determined in the standard or the like. Alternatively, the gNB may notify the UE of the various types of information in advance. The various types of information may be notified by RRC signaling or MAC signaling. The various types of information may also be dynamically notified by L1 / L2 signaling.

[0524] The various types of information may be notified by the UL grant for eMBB data. Since the transmission method and resource information of the preempted data can be dynamically notified, it is possible to make settings according to the radio wave propagation environment and the load situation. Therefore, it is possible to improve the uplink communication quality and also improve the resource utilization efficiency.

[0525] The gNB notifies the UE of the transmission method and resource information of the data in the case of preemption using PDCCH6001.

[0526] The UE that has determined to preferentially transmit URLLC data transmits the URLLC data on the resources 6003 allocated with the configured grant on non-SUL. If the transmission timing of the URLLC data overlaps with the resources 6005 on SUL that have been previously UL granted for eMBB data, the UE transmits the eMBB data according to the pre-configured transmission method and resource information.

[0527] Here, the transmission method of the preempted data is a shift on the same UL carrier, and the resource information of the transmission indicates the slot shifted 2 slots backward. The UE transmits the eMBB data on the resource 6006 shifted 2 slots backward from the resource 6005.

[0528] By doing so, it becomes possible to preferentially transmit the URLLC data at the timing of the resource 6005 allocated with the previously configured grant. Also, the preempted eMBB can be transmitted in the subsequent slot 6006.

[0529] Figure 52 is an example showing a method of preemption when a configured grant is set. A configured grant is set on non-SUL for URLLC data.

[0530] The resources 6102, 6103, 6104 for URLLC data are periodically allocated with the configured grant. A grant for eMBB data is transmitted from the gNB to the UE by PDCCH6101. The gNB notifies the UE of the data transmission method and resource information in case of preemption by PDCCH6101.

[0531] URLLC data occurs before the resource 6103 on non-SUL allocated with the eMBB data grant.

[0532] The UE that has determined to preferentially transmit URLLC data transmits the URLLC data on the resource 6103 allocated by the configured grant on the non-SUL. The UE transmits the eMBB data according to the preconfigured transmission method and resource information. Here, the transmission method of the preempted data is switching to a different UL carrier, and the resource information of the transmission indicates the slot with offset 0. The UE switches the UL carrier from the resource 6103 on the non-SUL to the resource 6105 on the SUL and transmits the eMBB data on the resource 6105 on the SUL.

[0533] In this way, by enabling preemption on the resource allocated by the configured grant, it becomes possible to allocate data by dynamic scheduling to this resource first.

[0534] Also, in this way, by enabling preemption on the resource allocated by the configured grant, it becomes possible to allocate low-priority data to this resource first.

[0535] Therefore, it is not necessary to reserve the resource allocated by the configured grant for high-priority data. Thus, it becomes possible to improve the resource utilization efficiency while obtaining low-latency characteristics.

[0536] FIG. 53 is an example showing a method of preemption when a configured grant is set. A configured grant is set on the non-SUL for URLLC data.

[0537] Resources 6202, 6203, and 6204 for URLLC data are periodically allocated by the configured grant. A grant for eMBB data is transmitted from the gNB to the UE by the PDCCH 6201. The gNB notifies the UE of the data transmission method and resource information in the case of being preempted by the PDCCH 6201.

[0538] URLLC data occurs before the resources 6205 on SUL allocated by the grant for eMBB data.

[0539] The UE that has determined to transmit URLLC data preferentially can choose to transmit on the resources 6003 on non-SUL allocated by the configured grant, or to transmit on the resources 6205 on SUL allocated by the UL grant for eMBB data. When multiple resources are allocated at the same timing in this way, the selection of the resources may be made by the UE. By enabling the UE to make a selection, the UE can select the resources to transmit in consideration of the UE's state, such as the remaining battery level and location.

[0540] For example, when the remaining battery level is low, it is determined to transmit on SUL. This can reduce the power consumption. For example, when the location from the base station is far, it is determined to transmit on SUL. This can improve the communication quality.

[0541] The selection of the resources may be statically determined by standards or the like. The signaling information volume can be reduced. Also, the gNB only needs to receive either of the resources, and the reception processing at the gNB can be facilitated.

[0542] Also, the gNB may select the resources in advance and notify the UE. Resource selection information indicating the selection result of the resources may be provided. The gNB notifies the UE of the resource selection information. The notification of the resource selection information may apply the service priority, the data priority, the transmission method of the preempted data, or the notification method of the resource information for the transmission.

[0543] By the gNB selecting the resources and configuring them for the UE, for example, configuration considering the uplink communication quality from the UE becomes possible. Therefore, it is possible to improve the communication quality.

[0544] Here, the case where URLLC data is transmitted using the resources 6205 allocated for eMBB data is shown. The UE determines to transmit the URLLC data using the resources 6205 on SUL. The UE transmits the eMBB data according to the preconfigured transmission method and resource information. Here, it is shown that, depending on the transmission method of the preempted data and the resource information of the transmission, the transmission is shifted two slots backward.

[0545] The UE shifts the resources used for transmitting the eMBB data from the resources 6205 on SUL to the resources 6206 and transmits the eMBB data.

[0546] In this way, when a plurality of resources are allocated at the same timing, by enabling the selection of the resources, it becomes possible to improve the communication quality of the data with higher priority. For this reason, it becomes possible to obtain further low-latency characteristics. Also, it becomes possible to achieve low power consumption.

[0547] Figs. 54 to 56 are an example showing a method of preemption when the numerologies of SUL and non-SUL are different and a configured grant is set on non-SUL for URLLC data. Figs. 54 to 56 show the case where the SCS of non-SUL is longer than the SCS of SUL, in other words, the symbol period of non-SUL is shorter than the symbol period of SUL.

[0548] Fig. 54 is a diagram showing the case where the eMBB data granted UL on SUL is preempted and transmitted after being shifted two slots backward. Since the preemption method in Fig. 54 is the same as that in Fig. 51, the description is omitted. Note that the elements 6301 to 6306 in Fig. 54 respectively correspond to the elements 6001 to 6006 in Fig. 51.

[0549] FIG. 55 is a diagram showing a case where eMBB data granted on UL on non-SUL is preempted and transmitted after being switched to a different UL carrier SUL. The offset value is set to -3 slots. The offset value may be included in the resource information.

[0550] Allocate the data with a lower priority by dynamic scheduling to the resources allocated by the configured grant first. The data with a lower priority allocated first can preempt the data with a higher priority when the data with a higher priority occurs, enabling the data with a higher priority to be transmitted with low latency. Since the preemption method in FIG. 55 is the same as that in FIG. 52, the description is omitted. Note that elements 6401 to 6405 in FIG. 55 respectively correspond to elements 6101 to 6105 in FIG. 52.

[0551] FIG. 56 is a diagram showing a case where eMBB data granted on SUL is preempted and transmitted after being shifted 2 slots backward. FIG. 56 shows a case where a plurality of resources 6503 and 6505 are allocated at the same timing. The UE determines to transmit URLLC data on the resource 6505 on SUL, for example, according to the standard, or based on the determination of the UE, or according to the notification from the gNB.

[0552] Since the preemption method in FIG. 56 is the same as that in FIG. 53, the description is omitted. Note that elements 6501 to 6506 in FIG. 56 respectively correspond to elements 6201 to 6206 in FIG. 53.

[0553] By doing so, even when a configured grant is set for URLLC data, it is possible to preferentially transmit the URLLC data. The URLLC data can be transmitted with low latency.

[0554] Embodiment 5. In a beam failure recovery request (hereinafter sometimes referred to as BFRQ) using PUCCH, it may be transmitted using PUCCH for SR. As another example, PUCCH for beam measurement result reporting may be used. The base station may perform the setting of PUCCH for BFRQ for the UE. For example, RRC signaling may be used for the setting.

[0555] However, in BFRQ using PUCCH, the details of the RRC signaling used for the setting of the PUCCH are not disclosed, and the format of the PUCCH for transmitting BFRQ is not disclosed. As a result, the UE cannot notify the base station of BFRQ using PUCCH. Also, in PUCCH for BFRQ, how to ensure reliability is not disclosed. As a result, the reliability in the notification of BFRQ from the UE to the base station cannot be ensured.

[0556] A solution to the above problem is disclosed below.

[0557] The UE transmits the PUCCH for BFRQ using a predetermined sequence. The application of the predetermined sequence may be performed, for example, when the BFRQ information includes only information regarding the occurrence or non-occurrence of beam failure, etc. The predetermined sequence may be, for example, a ZC sequence. Thereby, for example, the base station can detect the PUCCH quickly. In the PUCCH for BFRQ, parameters related to the sequence, such as the root index and / or the cyclic shift amount, may be made different from the sequences of the PUCCH for SR and / or ACK / NACK. Alternatively, in the PUCCH for BFRQ, the parameters may be made the same as those of the PUCCH for SR and / or ACK / NACK. When the parameters are made the same as those of the PUCCH for SR and / or ACK / NACK, the frequency and / or time resources of the PUCCH for BFRQ may be made different from those of the PUCCH for ACK / NACK. At the base station, the PUCCH for BFRQ can be distinguished from the PUCCH for SR and / or ACK / NACK.

[0558] As another example, the UE may transmit the PUCCH for BFRQ using PSK and / or QAM modulation (hereinafter may be referred to as PSK / QAM modulation). The PSK may be BPSK, QPSK, or other PSK schemes. The QAM may be 16QAM, 64QAM, 256QAM, or other QAM schemes. For PSK and QAM, the following may be the same. The application of PSK / QAM modulation may be performed, for example, when the BFRQ is composed of multiple bits, for example, when the BFRQ includes information regarding the beam described later.

[0559] The UE may transmit the PSK / QAM-modulated PUCCH for BFRQ together with the DMRS. The UE may frequency-division multiplex or time-division multiplex the PUCCH for BFRQ and the DMRS.

[0560] The UE may transmit the PUCCH for BFRQ as a short PUCCH. For example, the effect of frequency diversity can be obtained. It may also be transmitted as a long PUCCH. For example, the effect of time diversity can be obtained.

[0561] FIG. 57 is a diagram showing an example of the format of the PUCCH for BFRQ. FIG. 57 shows an example using PSK / QAM modulation as the modulation method of the PUCCH for BFRQ. Further, FIG. 57 shows an example using a 1-symbol short PUCCH as the PUCCH.

[0562] In FIG. 57, the information of BFRQ is PSK / QAM modulated and mapped to PUCCH1601. For demodulation of PUCCH1601, DMRS1602 is frequency multiplexed and mapped in the same symbol as PUCCH1601.

[0563] In FIG. 57, an example using a 1-symbol short PUCCH has been shown, but a short PUCCH of 2 symbols or more may be used, or a long PUCCH may be used. Further, an example of FDM of DMRS1602 with PUCCH1601 has been shown, but TDM may also be used.

[0564] The PUCCH for BFRQ may include information regarding the presence or absence of BFRQ. For example, the UE may indicate that there is BFRQ by transmitting the PUCCH, or the UE may indicate that there is no BFRQ by not transmitting the PUCCH. As another example, the UE may vary the sequence used for the PUCCH for BFRQ depending on the presence or absence of BFRQ. As another example, an identifier indicating the presence or absence of BFRQ may be included in the PUCCH. As another example, the modulation method of the PUCCH may vary depending on the presence or absence of BFRQ. For example, when there is BFRQ, the PUCCH may be PSK and / or QAM modulated, or when there is no BFRQ, the PUCCH may be composed of a predetermined sequence (e.g., ZC sequence).

[0565] The PUCCH for BFRQ may include information about the beam that has failed in beam failure. For example, it may include the identifier of the downlink beam, or information about the measurement result of the downlink beam by the UE. The base station may, for example, use the information about the measurement result to increase the transmission power of the downlink beam. As a result, for example, the UE can quickly recover the beam.

[0566] The PUCCH for BFRQ may include information about the beam measured by the UE. For example, it may include the identifier of the downlink beam, or information about the measurement result of the downlink beam by the UE. The beam information included in the information may be, for example, the beam information for which the measurement result of the UE is equal to or greater than a predetermined threshold. The threshold may be determined in advance by the standard, or may be notified in advance from the base station to the UE or individually notified. The beam information included in the information may be information about a plurality of beams. The base station may use the information for the recovery of the downlink beam. As a result, for example, the UE can quickly recover from beam failure.

[0567] Settings required for transmission of PUCCH for BFRQ from a UE may be defined in the standard. This can reduce, for example, the amount of signaling required for the settings. As another example, this information may be notified from the base station to the UE in advance, or may be notified individually. As an individual notification, for example, RRC signaling may be used. The RRC signaling may be, for example, RRC Connection Reconfiguration. This enables, for example, flexible control using the usage status of the UE, other UEs, and other base stations in a communication system. As another example, this information may be notified from the base station to the UE by MAC signaling, or may be notified from the base station to the UE using L1 / L2 signaling. This enables, for example, quick notification of this information to the UE. In making the settings, the above combinations may be used. For example, it may be defined in the standard to use sequence modulation for the PUCCH, and information regarding the sequence may be notified individually from the base station to the UE.

[0568] As settings required for transmission of PUCCH for BFRQ from a UE, the following (1) to (4) are disclosed below.

[0569] (1) Information regarding PUCCH transmission resources.

[0570] (2) Information regarding modulation schemes.

[0571] (3) Information regarding notifications from the UE.

[0572] (4) Combinations of the above (1) to (3).

[0573] The above (1) may include, for example, information regarding the transmission timing of PUCCH for BFRQ. This information may include information regarding the period and offset of transmission of PUCCH for BFRQ, or may include information regarding the number of transmission symbols. The above (1) may include information regarding the frequency resources of the PUCCH, or may include information indicating whether the PUCCH is a long PUCCH or a short PUCCH.

[0574] The above (2) may be modulation using, for example, PSK and / or QAM, or may be modulation using a sequence (e.g., ZC sequence).

[0575] In the above (2), for modulation using PSK and / or QAM, information regarding DMRS may be included. The information regarding DMRS may include, for example, information regarding the root index of DMRS, or information regarding the cyclic shift amount of DMRS. Information regarding the multiplexing scheme between DMRS and PUCCH may be included. The multiplexing scheme may be, for example, FDM or TDM.

[0576] In the above (2), for modulation using a sequence, information regarding the root index of the sequence or information regarding the cyclic shift amount of the sequence may be included.

[0577] The above (3) may include, for example, information regarding the presence or absence of notification of information regarding a beam. The beam may be a beam that has failed, a beam measured by the UE, or both of the above.

[0578] The above (3) may include information regarding a signal used by the UE in beam measurement. For example, it may be CSI-RS, SS (synchronization signal), or both of the above.

[0579] The above (3) may include information regarding the presence or absence of notification of measurement results.

[0580] Some or all of the information regarding the above (1) to (4) may be defined in advance by a standard. This can reduce, for example, the signaling amount in the notification from the base station to the UE.

[0581] The UE may notify the BFRQ at the earliest PUCCH transmission timing for BFRQ even after beam failure detection. By doing so, for example, the UE can quickly notify the base station of the BFRQ. As another example, the UE may notify the BFRQ at the earliest PUCCH transmission timing for BFRQ after detecting a new beam. By doing so, for example, a quick recovery from beam failure becomes possible.

[0582] Another solution is disclosed. The UE may transmit the BFRQ using the PUCCH for SR. It may be assumed that the information of SR and BFRQ is multiplexed on the same PUCCH. In the multiplexing of SR and BFRQ, the beam information may not be included in the BFRQ. For example, as the information of the BFRQ, only an identifier indicating that beam failure has occurred may be used.

[0583] In the PUCCH where the multiplexing is performed, a predetermined sequence may be used. The application of the predetermined sequence may be performed, for example, when the information of the BFRQ includes only information regarding the occurrence or non-occurrence of beam failure. For the predetermined sequence, different sequences may be used for each case of having only SR, having only BFRQ, and having both SR and BFRQ. When neither SR nor BFRQ exists, it may be assumed that the PUCCH is not transmitted. As the aforementioned different sequences, for example, the root index of the sequence may be different, the cyclic shift amount may be different, or the sequence itself may be different. For example, when there is a BFRQ, an m-sequence may be used. The aforementioned plurality may be used in combination. By doing so, for example, the base station can easily obtain information regarding SR and / or BFRQ. The base station may obtain information regarding SR and information regarding BFRQ from the sequence of the PUCCH.

[0584] As another example, in the multiplexed PUCCH, PSK / QAM modulation may be used. The application of PSK / QAM modulation may be performed, for example, when the BFRQ is composed of a plurality of bits, for example, when the BFRQ includes information regarding a beam. The PUCCH may include, for example, information regarding the presence or absence of SR, or information regarding the BFRQ (e.g., the presence or absence of BFRQ, information regarding a beam).

[0585] In the application of PSK / QAM modulation to the multiplexed PUCCH, the UE may multiplex and transmit the PSK / QAM modulated PUCCH and the DMRS. The multiplexing may be, for example, FDM or TDM. The base station may determine the presence or absence of the BFRQ using the signal received from the UE. For example, the base station may determine the presence or absence of the BFRQ using the fact that the QPSK signal and the DMRS signal are FDM. This enables the base station to easily determine the presence or absence of the BFRQ, for example.

[0586] In the application of PSK / QAM modulation to the multiplexed PUCCH, information regarding the presence or absence of SR may be included in the DMRS. For example, different DMRS sequences (e.g., root index, cyclic shift) may be used according to the presence or absence of SR. This enables an increase in the amount of information that can be included in the PUCCH, for example.

[0587] In the application of PSK / QAM modulation to the multiplexed PUCCH, it may be assumed that the PUCCH of other UEs is not transmitted in the time-frequency resource in which the PUCCH is transmitted. This prevents interference with the PUCCH of other UEs.

[0588] As another example, in the application of PSK / QAM modulation to the multiplexed PUCCH, in the time-frequency resources where the PUCCH is transmitted, the PUCCH of other UEs may be transmitted. The UE may transmit the PUCCH in a contention-based manner. The UE may retransmit the PUCCH to the base station by using the fact that beam recovery is not performed within a predetermined period and / or the UE does not receive an uplink grant from the base station. The aforementioned predetermined period may be defined by the standard or may be notified or informed in advance from the base station to the UE. This enables multiplexing with the PUCCH of other UEs, and as a result, the capacity of the communication system can be increased.

[0589] Regarding whether the PUCCH of other UEs can be transmitted in the time-frequency resources where the aforementioned PUCCH is transmitted, it may be applied to the PUCCH for other UCI.

[0590] In the multiplexed PUCCH, both a predetermined sequence and PSK / QAM modulation may be used. For example, in the PUCCH without BFRQ, that is, the PUCCH for SR only, a predetermined sequence may be used, or in the PUCCH with BFRQ, PSK / QAM modulation may be used. When neither SR nor BFRQ exists, it may be assumed that the PUCCH is not transmitted. This enables, for example, continued use of the conventional SR PUCCH in the communication system, thus avoiding the complexity of the design in the communication system.

[0591] As another example of the method for transmitting BFRQ using PUCCH for SR, a plurality of PUCCH arrangements may be used. For example, different arrangements may be used as the PUCCH arrangement according to the presence or absence of SR. Different PUCCH arrangements according to SR may be performed, for example, when BFRQ is composed of a plurality of bits, for example, when information regarding a beam is included in BFRQ. As another example, different arrangements may be used as the PUCCH arrangement according to the presence or absence of BFRQ. Different PUCCH arrangements according to the presence or absence of BFRQ may be performed, for example, when the information regarding BFRQ includes only information regarding the occurrence or non-occurrence of beam failure. The different arrangements may be, for example, those that swap signals between symbols, those that swap signals between subcarriers, or a combination of both. The aforementioned swapping between symbols may be the swapping between chunks of a plurality of symbols regarded as one chunk. The aforementioned swapping between subcarriers may be the swapping between chunks of a plurality of subcarriers regarded as one chunk. By this, for example, it becomes possible to multiplex BFRQ information without changing the sequence or the modulation method, so that it becomes possible to avoid the complexity of design in a communication system.

[0592] The information regarding the aforementioned plurality of arrangements may be defined by a standard, or may be notified in advance from a base station to a UE or notified individually.

[0593] The information included in the PUCCH in which SR and BFRQ are multiplexed may include part or all of the BFRQ information included in the PUCCH for BFRQ described above. It may include information regarding SR, for example, information regarding the presence or absence of SR. For example, when a sequence is used in the PUCCH in which SR and BFRQ are multiplexed, the PUCCH may have only information regarding the presence or absence of SR and information regarding the presence or absence of BFRQ.

[0594] In the transmission of BFRQ using PUCCH for SR, it may be possible to transmit only one of SR and BFRQ on one PUCCH. That is, either SR or BFRQ may be prioritized. In the foregoing, the format of the PUCCH may be the same as the format of the conventional PUCCH for SR or the format of the aforementioned PUCCH for BFRQ. This makes it possible to avoid, for example, the complexity of the design in a communication system.

[0595] Regarding the prioritization between SR and BFRQ, for example, the prioritized UCI may be statically determined by the standard, or may be notified or semi-statically notified from the base station to the UE. The semi-static notification may be, for example, RRC individual signaling. Alternatively, it may be dynamically notified from the base station to the UE using MAC signaling or L1 / L2 signaling.

[0596] As another example of the prioritization, the UCI generated earlier in the UE may be prioritized, or as another example, the UCI not transmitted on the immediately preceding PUCCH transmitted may be prioritized.

[0597] The settings required for the transmission of BFRQ using PUCCH for SR may be defined by the standard, similar to the settings required for the transmission of PUCCH for BFRQ, or may be notified or individually notified from the base station to the UE in advance.

[0598] In the notification from the base station to the UE using RRC individual signaling for the setting, the setting content may be included, for example, in the setting content of SR. This makes it possible for the base station to notify the UE of the SR setting and the BFRQ setting simultaneously, for example, so that the UE can execute the setting process quickly.

[0599] The following (1) to (6) are disclosed as the settings required for the transmission of BFRQ using PUCCH for SR.

[0600] (1) Information regarding PUCCH transmission resources.

[0601] (2) Information regarding the modulation method.

[0602] (3) Information regarding the notification from the UE.

[0603] (4) Information regarding the multiplexing of SR and BFRQ.

[0604] (5) Information regarding the PUCCH arrangement.

[0605] (6) Combinations of the aforementioned (1) to (5).

[0606] The aforementioned (1) may be the same as the setting (1) required for transmitting the PUCCH for BFRQ.

[0607] In the aforementioned (1), the information regarding the transmission timing of the PUCCH may be the same as the information regarding the transmission timing of SR. This facilitates the scheduling of the PUCCH in the base station.

[0608] The aforementioned (2) may be the same as the setting (2) required for transmitting the PUCCH for BFRQ.

[0609] In the aforementioned (2), the information regarding DMRS in the modulation using PSK and / or QAM may include the information of the DMRS sequence in each case of the presence / absence of SR. The information regarding the difference in the DMRS sequence (e.g., root index, cyclic shift amount) between the presence and absence of SR may also be included.

[0610] In the aforementioned (2), in the modulation using a sequence, the information of the sequence in each case of only SR, only BFRQ, and both SR and BFRQ may be included. The information regarding the difference in the sequence among the aforementioned three cases may also be included.

[0611] The above-mentioned (3) may include information similar to the settings (3) necessary for transmitting PUCCH for BFRQ, or may include information regarding SR notification.

[0612] The above-mentioned (4) may include, for example, information regarding the multiplexing possibility of SR and BFRQ on one PUCCH. When such multiplexing is not possible, it may be information indicating which of PUCCH and SR is prioritized.

[0613] The above-mentioned (5) may include, for example, information regarding the support possibility of different arrangements of PUCCH, or may include information indicating whether signal swapping is performed between symbols or between subcarriers, or may include information regarding the number of symbols and / or subcarriers grouped together.

[0614] The UE may detect a downlink communication beam. Such detection may be performed after beam failure detection in the UE. The signal used for beam detection in the UE may be determined in advance by the standard, or may be notified or individually informed to the UE from the base station. The signal may be, for example, CSI-RS or may be SS (synchronization signal). As another example, the UE may not perform the detection operation of the downlink communication beam.

[0615] The transmission timing of PUCCH transmitted from the UE to the base station, for example, the period and offset, may be the same regardless of the presence or absence of BFRQ. Thus, the base station can detect BFRQ by receiving PUCCH.

[0616] The UE may notify BFRQ at the earliest PUCCH transmission timing for SR even after beam failure detection. Thus, for example, the UE can notify BFRQ to the base station quickly. As another example, the UE may notify BFRQ at the earliest PUCCH transmission timing for SR after detecting a new beam. Thus, for example, a quick recovery from beam failure becomes possible.

[0617] The base station may change the downlink beam for the UE using the BFRQ. The base station may also transmit CSI-RS for other beams using the BFRQ. The arrangement of CSI-RS in other beams may be the same as that in the original beam. As a result, for example, the UE can detect other beams with the same arrangement as the original beam. Consequently, the UE can quickly perform beam detection to recover from beam failure.

[0618] Another solution is disclosed. The UE may transmit the BFRQ using the PUCCH for beam measurement result reporting. That is, the UE may include the information of the BFRQ in the beam measurement result report. The PUCCH may be a PUCCH for reporting the measurement result of the SS (synchronization signal) to the base station. The PUCCH may be newly provided.

[0619] The information of the BFRQ included in the beam measurement result report may include information regarding the presence or absence of the BFRQ (e.g., a flag indicating the presence or absence of the BFRQ), information using the beam identifier, or information regarding the beam measurement result. As information using the beam identifier, for example, it may be associated with the BFRQ that the beam identifier is a predetermined special value (e.g., all bits '0', all bits '1'). As information regarding the beam measurement result, for example, it may be associated with the BFRQ that the measurement result is below a predetermined threshold value. As another example, it may be associated with the BFRQ that the measurement result is a predetermined special value (e.g., all bits '0', all bits '1'). As a result, for example, the information on the presence or absence of the BFRQ and the information of the beam measurement result report can be shared. Consequently, it is possible to avoid the complexity in the design of the UE and the base station regarding the BFRQ.

[0620] The beam identifier and / or beam measurement result included in the BFRQ information included in the PUCCH for beam measurement result reporting may be the identifier and / or beam measurement result of the CSI-RS beam. As a result, for example, the base station can quickly execute recovery from beam failure using the information regarding the CSI-RS beam.

[0621] Alternatively, the BFRQ information included in the PUCCH for beam measurement result reporting may be only the information regarding the presence or absence of BFRQ. The base station may perform a recovery operation from beam failure using the information regarding the beam included in the beam measurement result report. As a result, for example, an increase in the signaling amount of the PUCCH for beam measurement result reporting including BFRQ can be suppressed.

[0622] As another example, the DMRS in the PUCCH for beam measurement result reporting may be changed using the BFRQ information. The change may be, for example, a change in the DMRS sequence. The change in the sequence may be, for example, a change in the root index, a change in the cyclic shift amount, or a combination of both. As a result, for example, the UE can quickly notify the base station of the PUCCH including BFRQ.

[0623] As another example, the PUCCH for beam measurement result reporting may not include the information of the beam measurement result. The PUCCH may include only the information regarding BFRQ. The information regarding BFRQ may be the same as in the case of multiplexing the BFRQ information in the PUCCH for beam measurement result reporting described above.

[0624] When the PUCCH includes only the information regarding BFRQ, modulation using a sequence may be performed. The modulation using a sequence may be performed, for example, in the same manner as the PUCCH for SR. As a result, for example, the base station can quickly detect BFRQ.

[0625] As another example of the method for transmitting BFRQ using PUCCH for SR, a plurality of PUCCH arrangements may be used. The plurality of arrangements described above may be the same as those in the example of the method for transmitting BFRQ using PUCCH for SR. For example, different arrangements may be used as the PUCCH arrangement according to the presence or absence of BFRQ. Different PUCCH arrangements according to the presence or absence of BFRQ may be performed, for example, when the information regarding BFRQ includes only the information regarding the presence or absence of beam failure.

[0626] The settings required for transmitting BFRQ using PUCCH for beam measurement result reporting may be determined in advance by a standard, notified from a base station to a UE, or individually notified, similar to the settings required for transmitting BFRQ using PUCCH for SR described above. As an individual notification, for example, RRC signaling may be used, MAC signaling may be used, or L1 / L2 signaling may be used. Thus, for example, an effect similar to multiplexing of SR and BFRQ can be obtained.

[0627] As the settings required for transmitting BFRQ using PUCCH for beam measurement result reporting described above, (1) to (6) are disclosed below.

[0628] (1) Information regarding PUCCH transmission resources.

[0629] (2) Information regarding modulation schemes.

[0630] (3) Information regarding notifications from the UE.

[0631] (4) Information regarding multiplexing of beam measurement results and BFRQ.

[0632] (5) Information regarding the arrangement of PUCCH.

[0633] (6) Combinations of (1) to (5) described above.

[0634] The above (1) may be the same as the settings (1) necessary for transmitting BFRQ using the PUCCH for SR. The information regarding the transmission timing of the PUCCH for beam measurement result reporting, including BFRQ, may be the same as the information regarding the transmission timing of the beam measurement result reporting. This facilitates the scheduling of PUCCH in the base station.

[0635] The above (2) may be the same as the settings (2) necessary for transmitting BFRQ using the PUCCH for SR.

[0636] In the above (2), the information regarding DMRS in the modulation using PSK and / or QAM may include the sequence information of DMRS in each case of the presence / absence of BFRQ. Information regarding the difference in the sequence of DMRS (e.g., root index, cyclic shift amount) between the presence and absence of BFRQ may also be included.

[0637] In the above (2), in the modulation using a sequence, the sequence information in the case where only BFRQ is present may be included.

[0638] The above (3) may be the same as the settings (3) necessary for transmitting BFRQ using the PUCCH for SR. Information regarding beam measurement result reporting may also be included.

[0639] The above (4) may be the same as the settings (4) necessary for transmitting BFRQ using the PUCCH for SR.

[0640] The above (5) may be the same as the settings (5) necessary for transmitting BFRQ using the PUCCH for SR.

[0641] The operation of the UE in transmitting BFRQ using the PUCCH for beam measurement result reporting may be the same as the operation of the UE in transmitting BFRQ using the PUCCH for SR. The operation of the base station may also be the same.

[0642] The PUCCH for beam measurement result reporting in Embodiment 5 may be periodic, semi-persistent, or aperiodic. For example, the UE may notify the BFRQ at the earliest PUCCH transmission timing for beam measurement result reporting even after beam failure detection. This enables the UE to quickly notify the base station of the BFRQ, for example. As another example, the UE may notify the BFRQ at the earliest PUCCH transmission timing for beam measurement result reporting after detecting a new beam. This enables, for example, a quick recovery from beam failure.

[0643] The PUCCH for beam measurement result reporting in Embodiment 5 may be a PUCCH for CSI. The UE may transmit the BFRQ using the PUCCH for CSI. When transmitting the BFRQ using the PUCCH for CSI, a method similar to the method of transmitting the BFRQ using the PUCCH for beam measurement result reporting may be used. This can achieve an effect similar to multiplexing of beam measurement results and the BFRQ.

[0644] In Embodiment 5, the BFRQ may be multiplexed with other UCI. The other UCI may be, for example, Ack / Nack. For BFRQ transmission using the PUCCH for Ack / Nack, a method similar to the BFRQ transmission using the PUCCH for SR or a method similar to the BFRQ transmission using the PUCCH for beam measurement result reporting may be used. This enables, for example, flexible configuration regarding the PUCCH.

[0645] The BFRQ transmissions using each PUCCH for UCI disclosed in Embodiment 5 may be combined. The aforementioned PUCCH may be periodic, semi-persistent, or aperiodic. A plurality of periodic, semi-persistent, and aperiodic PUCCHs may be combined. For example, the UE may notify the BFRQ at the earliest PUCCH transmission timing regardless of the UCI. This enables, for example, rapid notification from the UE to the base station.

[0646] The PUCCH including the BFRQ disclosed in Embodiment 5 may not be used for beam failure determination at the base station. The base station may determine beam failure at the UE using the reception status for each type of PUCCH transmission timing from the UE. The type of PUCCH transmission timing may be a periodic PUCCH, a semi-persistent PUCCH, or an aperiodic PUCCH. For example, if the base station receives a periodic PUCCH from the UE but cannot receive an aperiodic PUCCH from the UE, the base station may determine that there is a beam failure at the UE. As another example, if the base station cannot receive an aperiodic PUCCH from the UE, the base station may determine that there is a beam failure at the UE. In the foregoing, information regarding the reception or non-reception of a plurality of PUCCHs may be used. For example, if the base station cannot receive an aperiodic PUCCH continuously for a predetermined number of times or more, the base station may determine that there is a beam failure at the UE. In the foregoing, the base station may determine that it cannot receive the PUCCH using the fact that the reception quality of the PUCCH at the base station is below a predetermined quality. This enables, for example, reduction of the signaling amount in the radio interface.

[0647] The base station may transmit PDCCH to the UE using the information related to the beam included in the BFRQ. In the transmission of the PDCCH, the base station may use the beam obtained from the information. The UE may detect the PDCCH within a predetermined time window after the BFRQ transmission. This enables, for example, a quick recovery from beam failure.

[0648] The UE may transmit the PUCCH including the BFRQ using a plurality of beams. The PUCCH may be a PUCCH for BFRQ, a PUCCH for SR, a PUCCH for beam measurement result reporting, or a PUCCH for other UCI. This ensures, for example, the reliability in the BFRQ notification from the UE. As another example, the UE may transmit the PUCCH including the BFRQ multiple times. The multiple transmissions may, for example, transmit the same PUCCH in different symbols, transmit the same PUCCH in different slots, or transmit the same PUCCH in units of the PUCCH transmission period of each UCI. This improves, for example, the reliability of the BFRQ notification from the UE.

[0649] As another example, the UE may transmit the PUCCH including the BFRQ as a long PUCCH. The PUCCH may be a PUCCH for BFRQ, a PUCCH for SR, a PUCCH for beam measurement result reporting, or a PUCCH for other UCI. This ensures, for example, time diversity. As another example, the UE may transmit the PUCCH as a short PUCCH. This ensures frequency diversity. As another example, the UE may use a combination of a short PUCCH and a long PUCCH for the PUCCH. This ensures time and frequency diversity. The combination of the short PUCCH and the long PUCCH may, for example, be that the UE uses both the short PUCCH and the long PUCCH in the same slot.

[0650] The base station may pre-indicate to the UE how to send the PUCCH, either in the form of short PUCCH / long PUCCH / both short PUCCH and long PUCCH. For this indication, for example, RRC individual signaling, MAC signaling, or L1 / L2 signaling may be used.

[0651] According to Embodiment 5, the UE can transmit the BFRQ using the PUCCH. Also, in the UE, it is possible to quickly recover from beam failure.

[0652] Embodiment 6. In NR, for a UE with SUL configured, either the SUL or non-SUL is set as the UL carrier for PUCCH transmission. Here, this UL carrier is referred to as the PUCCH UL carrier. It has been discussed that when the transmission timings of PUSCH and PUCCH overlap, it is piggybacked on PUSCH. Also, in NR, it has been discussed to map and transmit the BFRQ on the PUCCH.

[0653] To enable early beam recovery, it is necessary to be able to transmit the BFRQ early. To enable early transmission of the BFRQ, it has been discussed to transmit the BFRQ on the PUCCH, which is an L1 control channel. However, when using the UL frequency existing in the same frequency band as the DL frequency, the communication quality in the UL may deteriorate along with the deterioration of the communication quality in the DL. If the communication quality in the UL deteriorates, there will be a problem that even if the UE sends the BFRQ with great effort, the gNB cannot receive the BFRQ. Therefore, improving the communication quality when transmitting the BFRQ becomes an issue.

[0654] Embodiment 6 discloses a method to solve such problems.

[0655] Transmit the BFRQ on the SUL. It may be possible to transmit the BFRQ on the SUL. Enable PUCCH transmission for the BFRQ on the SUL. Configure the PUCCH for the BFRQ on the SUL. When the coverage for enabling UL transmission on the SUL is wider than that on the non-SUL, transmitting the BFRQ on the SUL in this way can improve the communication quality of the BFRQ. Therefore, it is possible to notify the gNB of the BFRQ earlier.

[0656] Even if the non-SUL is configured for the PUCCH UL carrier, it may be possible to transmit the BFRQ on the SUL. It is advisable to enable the transmission of the PUCCH for the BFRQ on a UL carrier different from the configuration of the PUCCH UL carrier. Configure the PUCCH for the BFRQ on a UL carrier different from the configuration of the PUCCH UL carrier.

[0657] It may be possible to transmit the BFRQ on both the UL carriers of the SUL and the non-SUL. It is advisable to enable the transmission of the PUCCH for the BFRQ on both the UL carriers of the SUL and the non-SUL. Configure the PUCCH for the BFRQ on both the UL carriers of the SUL and the non-SUL.

[0658] The BFRQ is transmitted when the communication quality of the DL beam deteriorates. Therefore, as the PUCCH for the BFRQ, it is advisable to configure a periodic PUCCH resource that does not require a DL dynamic trigger. The configuration of the periodic PUCCH resource for the BFRQ may be performed by RRC signaling. The gNB may notify the UE of the periodic PUCCH resource for the BFRQ using RRC signaling.

[0659] As RRC signaling, the setting and release of PUCCH resources for BFRQ may be provided. Alternatively, setting and release information may be provided in the setting information of PUCCH resources for BFRQ. Or activation / deactivation information may be provided in the setting information of PUCCH resources for BFRQ. The UE performs the setting of PUCCH resources for BFRQ by setting or activation, and performs the release of PUCCH resources for BFRQ by release or deactivation.

[0660] By doing so, it becomes possible to set the resources of PUCCH for BFRQ without using the dynamic trigger of DL.

[0661] As a method for setting PUCCH resources for BFRQ, semi-persistent PUCCH resources may be set. As a method for setting semi-persistent PUCCH resources, activation / deactivation may be included in DCI and notified by PDCCH. The gNB may determine activation / deactivation for the UE according to the DL communication quality.

[0662] For example, a communication quality threshold for BFRQ is provided. In this case, a value better than the communication quality at which DL communication becomes impossible may be used as the threshold. It becomes possible to perform the notification of activation / deactivation from the gNB to the UE while DL communication is possible.

[0663] In addition, a communication quality measurement period for BFRQ may be provided. For example, the gNB notifies the UE to activate the PUCCH for BFRQ when the communication quality becomes lower than the communication quality threshold for BFRQ during the communication quality measurement period for BFRQ. The gNB notifies the UE to deactivate the PUCCH for BFRQ when the communication quality exceeds the communication quality threshold for BFRQ during the communication quality measurement period for BFRQ.

[0664] In the case of semi-persistent PUCCH for BFRQ, the allocated resources may be retained while it is activated, and the resources may be released while it is deactivated. By doing so, when the DL communication quality is good, there is no need to retain the resources for BFRQ, so the resources can be used for other UL communications. The resource utilization efficiency can be improved.

[0665] As a method for configuring semi-persistent PUCCH for BFRQ, although it has been disclosed to include activation / deactivation in DCI, the resource allocation of PUCCH may be notified together with activation. Also, the scheduling information may be notified together with activation. By doing so, it becomes possible to change the resource allocation of PUCCH for BFRQ, or the scheduling information, for each activation.

[0666] Compared with the configuration of periodic PUCCH for BFRQ, the configuration can be changed in the time axis direction, so it is possible to make a configuration according to the time variation of the radio propagation environment. The communication quality of PUCCH for BFRQ can be improved.

[0667] The PUCCH resources for BFRQ may be configured for each UE or for each of a plurality of UEs (groups). CDM may be used as a multiplexing method between UEs. The gNB may notify the UE by including the UE-specific code in the configuration information of the PUCCH for BFRQ. By doing so, there is no need to secure resources for each UE, so it becomes possible to increase the resource utilization efficiency.

[0668] The PUCCH for BFRQ may be a short PUCCH composed of a small number of symbols. Also, the PUCCH for BFRQ may be a long PUCCH composed of a large number of symbols. The beam measurement information may be included in the UCI and notified by the PUCCH for BFRQ.

[0669] The UE may determine whether to transmit the BFRQ using the PUCCH for BFRQ on SUL or the PUCCH for BFRQ on non-SUL. The UE may transmit the BFRQ at any PUCCH timing for BFRQ.

[0670] For example, the UE may set priorities and determine whether to transmit the BFRQ using the PUCCH for BFRQ on SUL or non-SUL according to the priorities. For example, the UE may prioritize the use of the PUCCH for BFRQ on SUL where an operation with a wider coverage than non-SUL is assumed. A UE that has detected a beam failure first transmits the BFRQ to the gNB using the PUCCH resource for BFRQ configured on SUL. If the UE fails to receive the signal after BFRQ delivery from the gNB, it transmits the BFRQ to the gNB using the PUCCH resource for BFRQ configured on non-SUL.

[0671] A timer may be provided to measure the time from BFRQ transmission to reception of the signal after BFRQ delivery. The timer is started with BFRQ transmission and stopped with reception of the BFRQ delivery signal. If the timer expires without receiving the BFRQ delivery signal, the BFRQ may be transmitted again. A maximum retransmission count for the BFRQ may be provided.

[0672] The gNB may set the timer and the maximum retransmission count for BFRQ and notify the UE. This notification may be performed by RRC signaling. Alternatively, the timer and the maximum transmission count for BFRQ may be statically determined by a standard or the like, which can reduce the amount of signaling information.

[0673] As another determination method by the UE, for example, the BFRQ may be transmitted using the PUCCH resource for BFRQ that arrives earlier after beam failure detection and after BFRQ configuration. After the UE configures the BFRQ, if the PUCCH resource timing for BFRQ configured on non-SUL is earlier, the UE transmits the BFRQ using the PUCCH resource for BFRQ configured on non-SUL.

[0674] For example, if the UE cannot receive the BFRQ delivery signal after transmitting the BFRQ and the timer expires, the UE may re-transmit the BFRQ at the earliest arriving PUCCH resource timing for the BFRQ. For example, if the earliest arriving PUCCH resource for the BFRQ is the PUCCH resource for the BFRQ configured in SUL, the UE transmits the BFRQ using the PUCCH resource for the BFRQ configured in SUL.

[0675] By doing so, it is possible to shorten the delay time until the BFRQ is transmitted. Since the BFRQ can be transmitted with low latency, it is possible to perform the recovery from the beam failure earlier.

[0676] The BFRQ may be transmitted continuously multiple times. The number of consecutive transmissions may be determined by the UE, or may be determined by the gNB and notified to the UE. Alternatively, the number of consecutive transmissions may be statically determined by a standard or the like. For example, the UE may transmit the BFRQ multiple times from the earliest arriving PUCCH resource for the BFRQ after beam failure detection and after BFRQ configuration. By transmitting the BFRQ continuously multiple times before receiving the BFRQ delivery signal or regardless of whether the signal can be received, the BFRQ can be transmitted with even lower latency. Furthermore, it is possible to perform the recovery from the beam failure earlier.

[0677] Disclosed is a method for configuring the UL carrier when the BFRQ is transmitted continuously multiple times. The PUCCH resource for the BFRQ on the UL carrier with the earliest arriving PUCCH resource timing for the BFRQ is used.

[0678] For example, assume that the continuous transmission count of the BFRQ is set to 3 times, the PUCCH for the earliest arriving BFRQ is set on the SUL, the PUCCH for the second arriving BFRQ is set on the SUL, and the PUCCH for the third arriving BFRQ is set on the non-SUL. In such a case, the UE performs the first BFRQ transmission using the PUCCH for the earliest arriving BFRQ on the SUL, the second BFRQ transmission using the PUCCH for the second arriving BFRQ on the SUL, and the third BFRQ transmission using the PUCCH for the third arriving BFRQ on the non-SUL.

[0679] When continuously transmitting the BFRQ multiple times, the pattern of the UL carrier for transmitting the BFRQ may be determined in advance. For example, the first BFRQ may be transmitted on the SUL and the second BFRQ may be transmitted on the non-SUL, so that the BFRQ is transmitted alternately on different UL carriers. By doing so, it is possible to obtain an effect similar to frequency hopping. By using different frequencies, the probability of the BFRQ being delivered can be improved.

[0680] Multiple consecutive transmissions may also be performed in the retransmission of the BFRQ. The same method as described above can be applied. By doing so, beam recovery can be enabled earlier.

[0681] The gNB may determine whether to transmit the BFRQ using the PUCCH for the BFRQ on the SUL or the PUCCH for the BFRQ on the non-SUL. The gNB notifies the UE of which PUCCH resource for the BFRQ to use for transmitting the BFRQ. When continuously transmitting the BFRQ multiple times, the gNB may determine the pattern of the UL carrier for transmitting the BFRQ and notify the UE. The same applies to the retransmission of the BFRQ.

[0682] UL carrier information for PUCCH transmission for BFRQ may be provided. The gNB notifies the UE of this information. The notification from the gNB to the UE may use RRC signaling. The UL carrier information may be included in DCI at activation time for notification. Also, the UL carrier for BFRQ transmission may be changed, and when changed, the gNB may notify the UE by including the UL carrier information in RRC signaling. Also, when changed, the gNB may notify the UE by including the UL carrier information in DCI.

[0683] By doing so, the gNB can set the UL carrier for the UE to transmit BFRQ. For example, the gNB measures the UL communication quality from the UE and, if the SUL has better communication quality than the non-SUL, decides to use the SUL for BFRQ transmission. Then, the gNB notifies the UE to use the PUCCH resource for BFRQ on the SUL. If the non-SUL has better communication quality than the SUL, the gNB decides to use the non-SUL for BFRQ transmission and notifies the UE to use the PUCCH resource for BFRQ on the non-SUL.

[0684] By doing so, the gNB can set the UL carrier for the UE to transmit BFRQ according to the radio propagation environment. The gNB can make the UE transmit BFRQ on a UL carrier with better communication quality. For this reason, the gNB can receive BFRQ from the UE earlier. The gNB can perform beam failure recovery from the UE earlier.

[0685] It may be possible to prohibit preemption for the PUCCH for BFRQ. It may be possible to prohibit the preemption of the resources for the PUCCH for BFRQ. The UE may not assume that the resources for the PUCCH for BFRQ are preempted. When receiving a preemption indication for the resources for the PUCCH for BFRQ from the gNB, the UE may ignore the preemption indication. It may be possible to prohibit preemption not only when the resources for the PUCCH for BFRQ overlap with the resources, but also when the resource timings overlap, on different UL carriers.

[0686] By doing so, when a beam failure occurs, it becomes possible to transmit BFRQ early using the PUCCH for BFRQ. The gNB can receive BFRQ from the UE early. The gNB can perform recovery from the beam failure for the UE early.

[0687] FIG. 58 is a diagram showing an example of transmitting BFRQ using the PUCCH resources for BFRQ set on SUL. FIG. 58 shows the case where the PUCCH UL carrier is set to non-SUL. For the PUCCH for BFRQ, remove the configurable UL carrier restriction. The PUCCH for BFRQ is set on a UL carrier different from the PUCCH UL carrier. The gNB sets the PUCCH for BFRQ for the UE on SUL, which is a UL carrier different from the PUCCH UL carrier.

[0688] Allocate periodic PUCCH resources 7002, 7003, and 7004 as the PUCCH for BFRQ. The UE that fails to receive DL in slot 7001 detects a beam failure and configures BFRQ transmission. At this time, it is determined to use the PUCCH resources for BFRQ set on SUL. The UE transmits BFRQ using the PUCCH resource 7004 for BFRQ on SUL.

[0689] By doing so, it becomes possible to configure PUCCH resources for BFRQ on SUL. For example, it becomes possible to transmit BFRQ on SUL in a frequency band different from the DL frequency band. It becomes possible to improve the communication quality of BFRQ. Therefore, the UE can notify the gNB of BFRQ at an early stage.

[0690] FIG. 59 is a diagram showing an example of transmitting BFRQ by configuring PUCCH resources for BFRQ on both non-SUL and SUL. The PUCCH UL carrier may be configured on either non-SUL or SUL. For the PUCCH for BFRQ, remove the configurable UL carrier restriction. The PUCCH for BFRQ is configured on both UL carriers. The gNB configures the PUCCH for BFRQ for the UE on both non-SUL and SUL.

[0691] Allocate periodic PUCCH resources 7102, 7103, and 7104 as PUCCH resources for BFRQ on non-SUL. Allocate periodic PUCCH resources 7105, 7106, and 7107 as PUCCH resources for BFRQ on SUL. The UE that fails to receive DL in slot 7101 detects the beam faiure and configures BFRQ transmission. At this time, the UE derives the earliest available PUCCH resource for BFRQ transmission.

[0692] FIG. 59 shows a case where the PUCCH resource 7106 for BFRQ configured on SUL is the earliest available PUCCH resource for BFRQ transmission because it is not possible to use the PUCCH resource 7103 for BFRQ on non-SUL during BFRQ configuration. The UE determines to transmit BFRQ using the PUCCH resource 7106 for BFRQ on SUL and transmits BFRQ using the PUCCH resource 7106.

[0693] By doing so, it becomes possible to set PUCCH resources for BFRQ on both non-SUL and SUL UL carriers. By setting PUCCH resources for BFRQ on both UL carriers, the UE can transmit BFRQ using the PUCCH resources for BFRQ at the earliest timing. Therefore, the UE can notify the gNB of BFRQ earlier.

[0694] Figure 60 is a diagram showing an example of setting PUCCH resources for BFRQ on both non-SUL and SUL and transmitting BFRQ. Figure 60 shows a case where SUL and non-SUL have different SCSs. Also, Figure 60 shows a case where the periods are set so that the PUCCH resources for BFRQ have the same timing on both UL carriers. The PUCCH UL carrier may be set to either non-SUL or SUL. For the PUCCH for BFRQ, remove the settable UL carrier restrictions. The PUCCH for BFRQ is set on both UL carriers. The gNB sets the PUCCH for BFRQ on both non-SUL and SUL for the UE.

[0695] Allocate periodic PUCCH resources 7202, 7203, and 7204 as PUCCH resources for BFRQ on non-SUL. Allocate periodic PUCCH resources 7205, 7206, and 7207 as PUCCH resources for BFRQ on SUL. The UE that fails to receive DL in slot 7201 detects the beam faiure and configures BFRQ transmission. At this time, determine in advance that the UL carrier to be preferentially used for transmitting BFRQ is SUL. Alternatively, the UL carrier with the longer SCS may be used as the carrier to be preferentially used for transmitting BFRQ.

[0696] The UE determines to transmit BFRQ using the PUCCH resources for BFRQ on SUL. The UE transmits BFRQ using the PUCCH resource 7206 for BFRQ on SUL.

[0697] Thus, for example, when the SUL is composed of frequencies in a frequency band different from that of the DL, by preferentially using the PUCCH resources for the BFRQ on the SUL, it becomes possible to increase the delivery probability of the BFRQ. Also, for example, when the coverage of the SUL is wider than that of the non-SUL, by using the PUCCH resources for the BFRQ on the SUL, it is also possible to increase the delivery probability of the BFRQ.

[0698] Also, for example, by using the PUCCH resources for the BFRQ set on the UL carrier with better communication quality among the non-SUL and the SUL, it becomes possible to increase the delivery probability of the BFRQ. The communication quality of the non-SUL or the SUL may be measured by the gNB, for example. The gNB may notify the UE of which PUCCH for the BFRQ on the non-SUL or the SUL is used to transmit the BFRQ.

[0699] By doing so, it becomes possible to transmit the BFRQ using the PUCCH resources for the BFRQ on the UL carrier with better communication quality. Therefore, the UE can notify the gNB of the BFRQ earlier.

[0700] After delivering the BFRQ to the gNB, beam recovery processing is performed. The UL carrier used in the processing after BFRQ delivery may be the UL carrier on which BFRQ transmission is performed. The gNB performs the processing after BFRQ delivery using the UL carrier on which the BFRQ is received. By doing so, it becomes possible to use a communicable UL carrier.

[0701] As another method, the gNB may notify the SUL / non-SUL indicator in the UL grant transmitted from the gNB to the UE in the processing after BFRQ delivery. The SUL / non-SUL indicator may be included in the DCI for the UL grant and notified by the PDCCH. The UE can recognize which UL carrier is used according to the indicator.

[0702] For the format of BFRQ, the information included in PUCCH, and the method of configuring PUCCH for BFRQ, the content disclosed in Embodiment 5 may be appropriately applied.

[0703] As disclosed in this Embodiment 6, by configuring the PUCCH resource for BFRQ on SUL, it becomes possible to transmit BFRQ with better communication quality compared to the conventional BFRQ transmission on non-SUL. By enabling the transmission of the PUCCH for BFRQ on both the UL carriers of SUL and non-SUL, it becomes possible to transmit the PUCCH for BFRQ on SUL even when the PUCCH for BFRQ cannot be transmitted on non-SUL. Also, by using PUCCH in this way, it becomes possible to transmit BFRQ earlier.

[0704] Therefore, it becomes possible to notify the gNB of BFRQ earlier, and the recovery period from the beam failure can be shortened.

[0705] It may also be possible to configure the PUCCH for BFRQ on non-SUL. There may be a case where non-SUL is configured with a longer SCS and a shorter symbol period than SUL. In such a case, by configuring the PUCCH resource for BFRQ on non-SUL, it becomes possible to notify the gNB of BFRQ earlier when a beam failure occurs, and the recovery period from the beam failure can be shortened.

[0706] When the PUCCH is configured for other signals on the UL carrier set on the PUCCH UL carrier, BFRQ may be transmitted using the resource for transmitting the PUCCH. The PUCCH for other signals may be configured periodically or semi-persistently. For example, there are the PUCCH for SR and the PUCCH for CSI.

[0707] For example, when the PUCCH for SR is configured on the PUCCH UL carrier, the resource for transmitting the PUCCH for SR is used for transmitting BFRQ on the UL carrier.

[0708] As described above, although it has been disclosed that the PUCCH for BFRQ is configured on both the UL carriers for SUL and non-SUL, by doing so, it is not necessary to configure the PUCCH for BFRQ on the PUCCH UL carrier.

[0709] Furthermore, the PUCCH for BFRQ may be configured on the PUCCH UL carrier. For BFRQ transmission on the PUCCH UL carrier, either the PUCCH for BFRQ or the PUCCH for other signals may be used. Using the resource for PUCCH that occurs at the earliest timing from the BFRQ configuration, BFRQ can be transmitted. By doing so, it is possible to obtain even lower latency characteristics.

[0710] Embodiment 7. In NR, the repetition of UL transmission data has been discussed. However, there has been no discussion about the repetition when it is possible to use multiple UL carriers for a UE with SUL configured. The repetition method when using multiple UL carriers is unknown.

[0711] In this Embodiment 7, a method for solving such problems is disclosed.

[0712] Perform repetition transmission on the same carrier. Perform repetition transmission on the UL carrier configured in the DCI of the initial transmission UL grant. In the DCI of the initial transmission UL grant, the SUL / non-SUL indicator may be used to configure the repetition transmission. By doing so, it is possible to avoid the complication of repetition transmission control. It is possible to reduce the malfunction in the gNB and UE.

[0713] Another method is disclosed. The UL carrier is switched during repeated transmission. Repeated transmission is performed by switching between SUL and non-SUL. The gNB may be able to configure whether to perform UL carrier switching during repeated transmission for the UE. Information indicating whether to perform UL carrier switching during repeated transmission may be provided. The gNB may notify the UE of this information by RRC signaling. This information may be notified together with the SUL configuration information to the UE. The gNB may notify the UE of this information by MAC signaling or L1 / L2 control signaling. The setting can be dynamically changed.

[0714] In one HARQ process, the UL carrier may be switched for each one or more repeated transmissions.

[0715] A method for switching the UL carrier is disclosed. A switching pattern is provided. For example, the UL carrier may be switched for each transmission. If the initial transmission is performed on the SUL, the second repeated transmission is performed on the non-SUL. The third repeated transmission is performed on the SUL. In this way, the UL carrier is alternately used repeatedly for the set number of transmissions.

[0716] The UL carrier may be alternately switched for each of a plurality of repeated transmissions. For example, the UL carrier is switched for every two transmissions. If the initial transmission is performed on the SUL, the initial transmission and the second repeated transmission are performed on the SUL, and the third and fourth repeated transmissions are performed on the non-SUL. In this way, the UL carrier is alternately transmitted repeatedly for the set number of transmissions.

[0717] The information of the initial UL carrier or the switching pattern may be statically determined by standards or the like. Alternatively, the gNB may determine the information and notify the UE. As a notification method, RRC signaling may be used. The information may be notified as notification information. This is effective when the same switching pattern is set for all UEs configured with in-cell SUL. The information may be notified by UE-specific or UE-group-specific signaling. The switching pattern can be set for each UE. For example, the switching pattern can be set in consideration of communication quality and the like on each UL carrier for each UE.

[0718] As a notification method, MAC signaling may be used. Reception errors can be reduced. As a notification method, L1 / L2 control signaling may be used. Since it can be notified dynamically, for example, it is possible to respond early to temporal changes in the radio propagation environment.

[0719] Regarding the initial UL carrier, it may be set by the initial DCI. The initial UL carrier may be set using the SUL / non-SUL indicator. By doing so, the initial UL carrier can be set, and thus the gNB can set a UL carrier with better communication quality for the UE at the initial transmission.

[0720] The gNB notifies the UE of UL grants on both the SUL and non-SUL UL carriers. The gNB notifies the UE of UL scheduling information on both the SUL and non-SUL UL carriers. The gNB may set the UL scheduling information in the initial DCI and notify the UE of the set information. By doing so, it becomes possible to allocate resources for repeated transmission on the SUL and non-SUL.

[0721] Another method is disclosed. The gNB sets the initial UL grant in the initial DCI and notifies the UE. The scheduling information for repeated transmissions starting from the second time may be derived from the scheduling information of the initial transmission. Only the resource allocation may be derived from the scheduling information of the initial transmission as the scheduling information. By doing so, it becomes possible to allocate resources for repeated transmissions on SUL and non-SUL.

[0722] Another method is disclosed. A hopping pattern across UL carriers may be determined in advance. The hopping pattern may be represented by a function such as the initial slot number, resource information in the initial frequency axis direction, etc. By doing so, it becomes possible to notify the UE from the gNB of the repeated transmission resources on different UL carriers with a small amount of information.

[0723] Another method is disclosed. During repeated transmission, the UL carrier for subsequent transmission may be included in the DCI and notified with the UL grant. A number may be set for the repeated transmission and included in the DCI. After the number, subsequent transmissions are performed on the UL carrier. This is effective, for example, when the number of repeated transmissions is large.

[0724] FIG. 61 is a diagram showing an example of repeated transmission when a plurality of UL carriers are set. FIG. 61 shows the case of performing repeated transmission on the same carrier. When SU...

Claims

1. A user equipment, and a base station that wirelessly communicates with the user equipment, wherein the user equipment in a communication system comprising: notifies the base station of capability information including information regarding a switching time between a plurality of uplink carriers; receives signaling regarding scheduling of uplink transmission by a dynamic grant from the base station; and stops other uplink transmissions at least the switching time before a start timing of the uplink transmission scheduled by the signaling. User equipment.

2. The plurality of uplink carriers include Supplemental UL (SUL), The user equipment according to claim 1.

3. A base station in a communication system comprising: a user equipment, and a base station that wirelessly communicates with the user equipment, wherein the base station: receives capability information including information regarding a switching time between a plurality of uplink carriers from the user equipment; transmits signaling regarding scheduling of uplink transmission by a dynamic grant to the user equipment; and stops other uplink transmissions to the base station at least the switching time before a start timing of the uplink transmission scheduled by the signaling. Base station.

4. A communication system comprising: a user equipment, and a base station that wirelessly communicates with the user equipment, wherein the user equipment: notifies the base station of capability information including information regarding a switching time between a plurality of uplink carriers; receives signaling regarding scheduling of uplink transmission by a dynamic grant from the base station; and stops other uplink transmissions at least the switching time before a start timing of the uplink transmission scheduled by the signaling. Communication system.

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