COMMUNICATION SYSTEM, USER EQUIPMENT AND MASTER BASE STATION

Abstract

We provide low-latency, highly reliable communication systems for NR (New Radio). [Solution] A communication system 200 includes a user device 202 and multiple base stations 203 that each wirelessly communicate with the user device 202. The multiple base stations 203 include a master base station and a secondary base station that configure dual connectivity for the user device 202. A grant configuration for grant-less uplink transmission to the secondary base station is configured in the secondary base station.

Description

[Technical Field]

[0001] The present invention relates to a communication system or the like that performs wireless communication between a communication terminal device such as a mobile terminal device and a base station device. [Background technology]

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

[0003] LTE uses OFDM (Orthogonal Frequency Division Multiplexing) for downlink and SC-FDMA (Single Carrier Frequency Division Multiple Access) for uplink as its access method. Unlike W-CDMA (Wideband Code Division Multiple Access), LTE does not include circuit switching and is only a packet communication method.

[0004] The decisions made by 3GPP regarding the frame configuration in the LTE system, as described in Non-Patent Document 1 (Chapter 5), will be explained using Figure 1. Figure 1 is an explanatory diagram showing the configuration of a radio frame used in an LTE communication system. In Figure 1, one radio frame is 10 ms. The radio frame is divided into 10 equally sized subframes. The subframe is divided into two equally sized slots. The first and sixth subframes of each radio frame include a downlink synchronization signal. The synchronization signals include a primary synchronization signal (P-SS) and a secondary synchronization signal (S-SS).

[0005] The decisions made by 3GPP regarding the channel configuration in the LTE system 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 in a CSG (Closed Subscriber Group) cell.

[0006] The Physical Broadcast Channel (PBCH) is a channel for downlink transmission from a base station (hereinafter simply referred to as a "base station") to a communication terminal (hereinafter simply referred to as a "communication terminal") such as a mobile terminal (hereinafter simply referred to as a "mobile terminal"). A BCH transport block is mapped to four subframes in a 40 ms interval. There is no explicit signaling of the 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 communication terminal of the number of Orthogonal Frequency Division Multiplexing (OFDM) symbols used for PDCCHs. The PCFICH is transmitted every subframe.

[0008] The Physical Downlink Control Channel (PDCCH) is a channel for downlink transmission from a base station to a communication terminal. The PDCCH reports resource allocation information for a Downlink Shared Channel (DL-SCH), which is one of the transport channels described below, resource allocation information for a Paging Channel (PCH), which is also one of the transport channels described below, and Hybrid Automatic Repeat reQuest (HARQ) information for the DL-SCH. The PDCCH carries an uplink scheduling grant. The PDCCH carries Acknowledgement (Ack) / Negative Acknowledgement (Nack), which are response signals to uplink transmissions. 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. A Downlink Shared Channel (DL-SCH), which is a transport channel, and a PCH, which is also a transport channel, are mapped to the PDSCH.

[0010] A physical multicast channel (PMCH) is a channel for downlink transmission from a base station to communication terminals, and a 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 Ack / Nack, which are response signals to downlink transmissions. The PUCCH also carries CQI (Channel Quality Indicator) reports. CQI is quality information that indicates the quality of received data or the quality of the communication path. The PUCCH also carries Scheduling Requests (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 channel for downlink transmission from a base station to a communication terminal. The PHICH carries Ack / Nack, which are response signals to uplink transmission. The Physical Random Access Channel (PRACH) is a channel for uplink transmission from a communication terminal to a base station. The PRACH carries a random access preamble.

[0014] Downlink reference signals (RS) are symbols known in LTE communication systems. The following five types of downlink reference signals are defined: Cell-specific Reference Signal (CRS), MBSFN Reference Signal, UE-specific reference signal Demodulation Reference Signal (DM-RS), Positioning Reference Signal (PRS), and Channel State Information Reference Signal (CSI-RS). Measurement of the physical layer of a communication terminal includes measurement of the reference signal received power (RSRP).

[0015] The transport channels described in Non-Patent Document 1 (Chapter 5) will be explained below. Among the downlink transport channels, a broadcast channel (BCH) is broadcast to the entire coverage of the base station (cell). The BCH is mapped to a physical broadcast channel (PBCH).

[0016] Retransmission control using HARQ (Hybrid ARQ) is applied to the Downlink Shared Channel (DL-SCH). DL-SCH can be broadcast to the entire coverage of a base station (cell). DL-SCH supports dynamic or semi-static resource allocation. Semi-static resource allocation is also called persistent scheduling. DL-SCH supports discontinuous reception (DRX) in communication terminals to reduce power consumption of communication terminals. DL-SCH is mapped to the Physical Downlink Shared Channel (PDSCH).

[0017] The Paging Channel (PCH) supports DRX in communication terminals to enable low power consumption in communication terminals. The PCH is required to broadcast to the entire coverage of the base station (cell). The PCH is mapped to physical resources such as the Physical Downlink Shared Channel (PDSCH) that can be dynamically used for traffic.

[0018] The Multicast Channel (MCH) is used for broadcasting to the entire coverage of a base station (cell). The MCH supports SFN combining of MBMS (Multimedia Broadcast Multicast Service) services (MTCH and MCCH) in multi-cell transmission. The MCH supports semi-static resource allocation. The MCH is mapped to the PMCH.

[0019] Among the uplink transport channels, the Uplink Shared Channel (UL-SCH) is subject to retransmission control using HARQ (Hybrid ARQ). The UL-SCH supports dynamic or semi-static resource allocation. The UL-SCH is mapped to the Physical Uplink Shared Channel (PUSCH).

[0020] The Random Access Channel (RACH) is limited to control information. The RACH is subject to collision risk. The RACH is mapped to the Physical Random Access Channel (PRACH).

[0021] We will explain HARQ. HARQ is a technology that improves the communication quality of a transmission channel by combining Automatic Repeat reQuest (ARQ) and Forward Error Correction. HARQ has the advantage that error correction works effectively through retransmission even on transmission channels where communication quality varies. In particular, by combining the reception results of the initial transmission and the retransmission when retransmitting, it is possible to achieve further quality improvement.

[0022] An example of a retransmission method will be explained below. If the receiving side is unable to decode the received data correctly, in other words, if a CRC (Cyclic Redundancy Check) error occurs (CRC=NG), the receiving side will send a "Nack" to the sending side. The sending side, having received the "Nack," will retransmit the data. If the receiving side is able to decode the received data correctly, in other words, if no CRC error occurs (CRC=OK), the receiving side will send an "Ack" to the sending side. The sending side, having received the "Ack," will send the next data.

[0023] The logical channels described in Non-Patent Document 1 (Chapter 6) will be explained below. 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) or the downlink shared channel (DL-SCH), which are transport channels.

[0024] The Paging Control Channel (PCCH) is a downlink channel for transmitting paging information and changes to system information. 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.

[0025] A Common Control Channel (CCCH) is a channel for transmission control information between a communication terminal and a base station. CCCH is used when a communication terminal does not have an RRC connection with the network. In the downlink direction, CCCH is mapped to a Downlink Shared Channel (DL-SCH), which is a transport channel. In the uplink direction, CCCH is mapped to an Uplink Shared Channel (UL-SCH), which is a transport channel.

[0026] The Multicast Control Channel (MCCH) is a downlink channel for point-to-multipoint transmission. The MCCH is used to transmit MBMS control information for one or several MTCHs from the network to communication terminals. The MCCH is used only by communication terminals receiving MBMS. The MCCH is mapped to the Multicast Channel (MCH), which is a transport channel.

[0027] A 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 is in an RRC connection. The DCCH is mapped to an uplink shared channel (UL-SCH) in the uplink and to a downlink shared channel (DL-SCH) in the downlink.

[0028] A Dedicated Traffic Channel (DTCH) is a one-to-one communication channel for transmitting user information to an individual communication terminal. DTCH exists in both uplink and downlink. In uplink, DTCH is mapped to an uplink shared channel (UL-SCH) and in downlink, it is mapped to a downlink shared channel (DL-SCH).

[0029] The Multicast Traffic Channel (MTCH) is a downlink channel for transmitting traffic data from the network to communication terminals. The MTCH is a channel used only by communication terminals receiving MBMS. The MTCH is mapped to the Multicast Channel (MCH).

[0030] CGI stands for Cell Global Identifier. ECGI stands for E-UTRAN Cell Global Identifier. Closed Subscriber Group (CSG) cells are introduced in LTE, LTE-A (Long Term Evolution Advanced) (described below), and UMTS (Universal Mobile Telecommunication System).

[0031] A CSG (Closed Subscriber Group) cell is a cell for which an operator has identified available subscribers (hereinafter referred to as a "specific subscriber cell"). The identified subscribers are permitted to access one or more cells in a PLMN (Public Land Mobile Network). The one or more cells to which the identified subscribers are permitted to access are called "CSG cell(s)." However, there are access restrictions within the PLMN.

[0032] A CSG cell is a part of a PLMN that broadcasts a unique CSG identity (CSG ID) and broadcasts a CSG indication of "TRUE." Members of a pre-registered and authorized subscriber group access the CSG cell using the CSG ID, which is access permission information.

[0033] The CSG ID is broadcast by a CSG cell or cells. There are multiple CSG IDs in an LTE communication system. The CSG ID is used by a communication terminal (UE) to facilitate access by CSG-related members.

[0034] The location of a communication terminal is tracked in units of an area consisting of one or more cells. Location tracking is performed to track the location of the communication terminal even when it is in standby mode and to enable the communication terminal to be called, in other words, to allow the communication terminal to receive calls. The area used for tracking the location of this communication terminal is called a tracking area.

[0035] 3GPP is studying base stations called Home-NodeB (Home-NB; HNB) and Home-eNodeB (Home-eNB; HeNB). HNB in ​​UTRAN and HeNB in ​​E-UTRAN are base stations for access services for homes, businesses, and businesses, for example. Non-Patent Document 2 discloses three different modes of access to HeNB and HNB. Specifically, it discloses an open access mode, a closed access mode, and a hybrid access mode.

[0036] 3GPP is also working on the development of the Long Term Evolution Advanced (LTE-A) standard as Release 10 (see Non-Patent Documents 3 and 4). LTE-A is based on the LTE wireless communication system, and is configured by adding several new technologies to it.

[0037] In the LTE-A system, carrier aggregation (CA) is being considered, which aggregates two or more component carriers (CCs) (also called "aggregation") to support wider frequency bandwidths (transmission bandwidths) up to 100 MHz. CA is described in Non-Patent Document 1.

[0038] 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).

[0039] Depending on the UE's capabilities, a secondary cell (SCell) is configured to form a serving cell set 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).

[0040] A set of serving cells, which includes one PCell and one or more SCells, is configured for one UE.

[0041] Furthermore, new technologies for LTE-A include wider bandwidth extension and Coordinated Multiple Point transmission and reception (CoMP) technology. CoMP, which is being considered for LTE-A by 3GPP, is described in Non-Patent Document 1.

[0042] Furthermore, in order to handle future massive traffic volumes, 3GPP is considering using small eNBs (hereinafter sometimes referred to as "small-scale base station devices") that configure small cells. For example, technologies are being considered that aim to increase communication capacity by installing a large number of small eNBs and configuring a large number of small cells to improve frequency utilization efficiency. Specifically, there is dual connectivity (abbreviated as DC), in which a UE connects to two eNBs to communicate. DC is described in Non-Patent Document 1.

[0043] Of the eNBs that perform dual connectivity (DC), one may be referred to as a "master eNB (abbreviated as MeNB)" and the other as a "secondary eNB (abbreviated as SeNB)."

[0044] Mobile network traffic volume is on the rise, and communication speeds are also increasing. Once LTE and LTE-A are fully operational, communication speeds are expected to increase even further.

[0045] Furthermore, in response to the increasing sophistication of mobile communications, fifth-generation (hereinafter sometimes referred to as "5G") wireless access systems are being considered, with the goal of launching services after 2020. For example, in Europe, an organization called METIS has compiled requirements for 5G (see Non-Patent Document 5).

[0046] The requirements for a 5G wireless access system are that it will have 1,000 times the system capacity, 100 times the data transmission speed, one-tenth (1 / 10) the data processing delay, and 100 times the number of simultaneous connections of communication terminals compared to an LTE system, while also achieving further reductions in power consumption and lower equipment costs.

[0047] To meet these demands, 3GPP is currently studying the 5G standard as Release 15 (see Non-Patent Documents 6 to 10). 5G wireless technology is called "New Radio Access Technology" ("New Radio" is abbreviated as "NR"), and several new technologies are being studied (see Non-Patent Documents 11, 15, and 16). For example, DC using LTE and NR, and frequency resource sharing between LTE and NR are being studied (see Non-Patent Documents 12 and 13). [Prior art documents] [Non-patent literature]

[0048] [Non-Patent Document 1] 3GPP TS 36.300 V14.3.0

Non-Patent Document 2

Non-Patent Document 3

Non-Patent Document 4

Non-Patent Document 5

Non-Patent Document 6

Non-Patent Document 7

Non-Patent Document 8

Non-Patent Document 9

Non-Patent Document 10

Non-Patent Document 11

Non-Patent Document 12

Non-Patent Document 13

Non-Patent Document 14

Non-Patent Document 15

Non-Patent Document 16

Non-Patent Document 17

Non-Patent Document 18

Summary of the Invention

[0049] In NR, DC using eNB and gNB is being discussed. NR also requires low-latency and high-reliability communications. However, when DC is configured, the destination of uplink data transmitted from the UE is determined by the buffer capacity of the uplink data. Therefore, in communications requiring low latency, the UE cannot necessarily transmit uplink data to a base station with low latency. This increases the latency of uplink data transmission.

[0050] In addition, control technologies for sharing the same frequency for LTE and NR are being discussed. UEs communicate with eNBs and / or gNBs by switching between LTE and NR transmitters and / or receivers. However, when LTE and NR frequencies are shared, the timing of the LTE and NR synchronization signals overlap, which causes the UE to be unable to receive synchronization signals from the eNB and / or gNB, making LTE and / or NR communications impossible.

[0051] In view of the above problems, one of the objects of the present invention is to provide a low-latency and highly reliable communication system in NR. [Means for solving the problem]

[0052] According to the present invention, there is provided, for example, a communication system comprising a user device and a plurality of base stations each communicating wirelessly with the user device, wherein the plurality of base stations include a master base station and a secondary base station that form dual connectivity for the user device, and the secondary base station is configured with a grant configuration for grant-less uplink transmission to the secondary base station.

[0053] Furthermore, according to the present invention, there is provided, for example, a user equipment in a communication system including a user equipment and a plurality of base stations each of which wirelessly communicates with the user equipment, wherein the plurality of base stations include a master base station and a secondary base station that form dual connectivity for the user equipment, and the user equipment performs uplink communication based on a grant configuration for uplink grant-less transmission to the secondary base station.

[0054] Furthermore, according to the present invention, there is provided, for example, a base station in a communication system including a user device and a plurality of base stations each communicating wirelessly with the user device, wherein the plurality of base stations include a master base station and a secondary base station that form dual connectivity for the user device, and the base station sets a grant configuration for grant-less uplink transmission to the secondary base station in the secondary base station. [Effects of the Invention]

[0055] According to the present invention, it is possible to provide a low-delay, highly reliable communication system in NR.

[0056] The objects, features, aspects, and advantages of the present invention will become more apparent from the following detailed description and the accompanying drawings. [Brief explanation of the drawings]

[0057] [Figure 1] FIG. 1 is an explanatory diagram showing the configuration of a radio frame used in an LTE communication system. [Figure 2] 1 is a block diagram showing the overall configuration of an LTE communication system 200 being discussed in 3GPP. [Figure 3] FIG. 3 is a block diagram showing the configuration of a mobile terminal 202 shown in FIG. [Figure 4] FIG. 3 is a block diagram showing the configuration of a base station 203 shown in FIG. [Figure 5] FIG. 2 is a block diagram illustrating the configuration of an MME. [Figure 6] 1 is a flowchart showing an outline of operations from cell search to standby operation performed by a communication terminal (UE) in an LTE communication system. [Figure 7] FIG. 1 is a diagram illustrating the concept of a cell configuration when macro eNBs and small eNBs are mixed. [Figure 8] FIG. 10 is a diagram showing an example of a sequence in which an MN sets to a UE which node an uplink transmission should be made to, in accordance with the first embodiment. [Figure 9] FIG. 10 is a diagram showing an example of a sequence in which a UE determines an uplink transmission node according to the first embodiment. [Figure 10] FIG. 10 is a diagram showing an example of a sequence in which a UE determines an uplink transmission node using a threshold value according to the first embodiment. [Figure 11] FIG. 10 is a diagram showing an example of a sequence in which a UE determines an uplink transmission node using a threshold value according to the first embodiment. [Figure 12] FIG. 10 is a diagram showing an example of a sequence in which an SN performs no grant transmission in a split bearer, in accordance with a first variant of the first embodiment. [Figure 13] FIG. 10 is a diagram showing an example of a sequence in which an SN performs no grant transmission in a split bearer, in accordance with a first variant of the first embodiment. [Figure 14] FIG. 10 is a diagram showing another example of a sequence in which an SN performs no grant transmission in a split bearer, in accordance with the first modification of the first embodiment. [Figure 15] FIG. 10 is a diagram showing another example of a sequence in which an SN performs no grant transmission in a split bearer, in accordance with the first modification of the first embodiment. [Figure 16] FIG. 10 is a diagram showing another example of a sequence in which an SN performs no grant transmission in a split bearer, in accordance with the first modification of the first embodiment. [Figure 17] FIG. 10 is a diagram showing another example of a sequence in which an SN performs no grant transmission in a split bearer, in accordance with the first modification of the first embodiment. [Figure 18]FIG. 10 is a diagram showing an example of a sequence in which an MN and an SN perform grant non-transmission in a split bearer, according to a first modification of the first embodiment. [Figure 19] FIG. 10 is a diagram showing an example of a sequence in which an MN and an SN perform grant non-transmission in a split bearer, according to a first modification of the first embodiment. [Figure 20] FIG. 10 is a diagram showing another example of a sequence in which an SN performs no grant transmission in a split bearer, in accordance with the first modification of the first embodiment. [Figure 21] FIG. 10 is a diagram showing another example of a sequence in which an SN performs no grant transmission in a split bearer, in accordance with the first modification of the first embodiment. [Figure 22] FIG. 10 is a diagram showing another example of a sequence in which an SN performs no grant transmission in a split bearer, in accordance with the first modification of the first embodiment. [Figure 23] FIG. 10 is a diagram showing another example of a sequence in which an SN performs no grant transmission in a split bearer, in accordance with the first modification of the first embodiment. [Figure 24] FIG. 11 is a diagram showing an example of a sequence for setting no grant transmission in packet duplication according to the second embodiment. [Figure 25] FIG. 11 is a diagram showing an example of a sequence for setting no grant transmission in packet duplication according to the second embodiment. [Figure 26] FIG. 11 is a diagram showing an example of a sequence for setting no grant transmission in packet duplication according to the second embodiment. [Figure 27] FIG. 11 is a diagram showing an example of a sequence for setting packet duplication for uplink communication for which no grant transmission is set, according to the second embodiment. [Figure 28] FIG. 11 is a diagram showing an example of a sequence for setting packet duplication for uplink communication for which no grant transmission is set, according to the second embodiment. [Figure 29] FIG. 11 is a diagram showing an example of a sequence for setting packet duplication for uplink communication for which no grant transmission is set, according to the second embodiment. [Figure 30]FIG. 11 is a diagram showing an example of a sequence for performing packet duplication and grant no-transmission setting by notifying packet duplication act and grant no-transmission setting act using the same signaling, in accordance with the second embodiment. [Figure 31] FIG. 11 is a diagram showing an example of a sequence for performing packet duplication and grant no-transmission setting by notifying packet duplication act and grant no-transmission setting act using the same signaling, in accordance with the second embodiment. [Figure 32] FIG. 11 is a diagram illustrating an example in which an uplink preemption instruction is given using a frequency resource different from a region used for transmitting and receiving downlink user data, according to the third embodiment. [Figure 33] FIG. 11 is a diagram illustrating an example in which an uplink preemption instruction is sent via a PDCCH in accordance with the third embodiment. [Figure 34] FIG. 10 is a diagram illustrating an example of using a predetermined code as information indicating the occurrence of preemption, in accordance with the first modification of the third embodiment. [Figure 35] A figure showing an example of rearrangement of SS blocks in an NR SS burst for embodiment 4. [Figure 36] FIG. 11 is a timing diagram showing transmission of NR SS blocks that do not overlap with LTE non-MBSFN signals in accordance with the fourth embodiment. [Figure 37] FIG. 11 is a diagram illustrating an example in which an offset is provided at the frame boundary between LTE and NR in accordance with the fourth embodiment. [Figure 38] FIG. 11 is a diagram showing an example of rearrangement of NR SS burst signals in accordance with the fourth embodiment. [Figure 39] FIG. 13 is a sequence diagram showing a procedure in which a master base station instructs a UE to perform single TX / dual TX, according to the fifth embodiment. [Figure 40] FIG. 13 is a sequence diagram showing notification of SCell information when activating / deactivating an SCell according to a fifth embodiment. [Figure 41] FIG. 13 is a diagram illustrating an example of transmitting LTE PUCCH and NR PUCCH in the same subframe in single TX, in accordance with a first modification of the fifth embodiment. [Figure 42] This figure shows a sequence in which a UE determines the path loss of an SUL using a downlink measurement signal from an NR base station in accordance with a sixth embodiment. [Figure 43] FIG. 20 is a diagram illustrating an example of preemption of an FL-DMRS for eMBB UE according to the seventh embodiment. [Figure 44] FIG. 20 is a diagram illustrating an example of preemption of an FL-DMRS for eMBB UE according to the seventh embodiment. [Figure 45] FIG. 20 is a diagram illustrating an example of preempting FL-DMRS when FL-DMRS and add-DMRS are configured for eMBB UE, according to the seventh embodiment. [Figure 46] FIG. 20 is a diagram illustrating an example of preempting FL-DMRS when only FL-DMRS is configured in one slot for eMBB UE, according to the seventh embodiment. [Figure 47] FIG. 20 is a diagram illustrating an example of a sequence of a process for preempting FL-DMRS when only FL-DMRS is configured in a slot for eMBB UE, according to a seventh embodiment. [Figure 48] FIG. 20 is a diagram illustrating an example of a sequence of a process for preempting FL-DMRS when only FL-DMRS is configured in a slot for eMBB UE, according to a seventh embodiment. [Figure 49] FIG. 20 is a diagram illustrating an example of preempting FL-DMRS when only FL-DMRS is configured in one slot for eMBB UE, according to the seventh embodiment. [Figure 50] FIG. 20 is a diagram illustrating an example of preempting FL-DMRS when only FL-DMRS is configured in one slot for eMBB UE, according to the seventh embodiment. [Figure 51] FIG. 20 is a diagram illustrating an example of preempting FL-DMRS when only FL-DMRS is configured in one slot for eMBB UE, according to the seventh embodiment. [Figure 52]FIG. 20 is a diagram illustrating an example of preempting FL-DMRS when only FL-DMRS is configured in one slot for eMBB UE, according to the seventh embodiment. [Figure 53] FIG. 13 is a diagram illustrating an example of preemption when FL-DMRS, add-DMRS, and PUCCH and / or SRS are configured for eMBB UE, according to a second modification of the seventh embodiment. [Figure 54] FIG. 13 is a diagram illustrating an example of preemption when FL-DMRS, add-DMRS, and PUCCH and / or SRS are configured for eMBB UE, according to a second modification of the seventh embodiment. [Figure 55] FIG. 13 is a diagram illustrating an example of preemption when FL-DMRS, add-DMRS, and PUCCH and / or SRS are configured for eMBB UE, according to a second modification of the seventh embodiment. [Figure 56] FIG. 20 is a diagram illustrating an example of preempting FL-DMRS when only FL-DMRS is configured in one slot for eMBB UE, according to a second modification of the seventh embodiment. [Figure 57] FIG. 20 is a diagram illustrating an example of a preemption method when a complementary SRS is set, in accordance with the second modification of the seventh embodiment. [Figure 58] FIG. 22 is a diagram illustrating an example of a preemption method when a complementary PUCCH is configured, according to the second modification of the seventh embodiment. [Figure 59] FIG. 20 is a diagram showing an example of setting preemption for SR in accordance with the third modification of the seventh embodiment. [Figure 60] FIG. 20 is a diagram illustrating an example of a method for preempting repeated transmission of data for URLLC UE that spans slots for eMBB UE, in accordance with a fourth modification of the seventh embodiment. [Figure 61] FIG. 20 is a diagram illustrating an example of a method for preempting repeated transmission of data for URLLC UE that spans slots for eMBB UE, in accordance with a fourth modification of the seventh embodiment. [Figure 62]FIG. 20 is a diagram illustrating an example of a method for preempting repeated transmission of data for URLLC UE that spans slots for eMBB UE, in accordance with a fourth modification of the seventh embodiment. [Figure 63] FIG. 20 is a diagram illustrating an example of a method for preempting repeated transmission of data for URLLC UE that spans slots for eMBB UE, in accordance with a fourth modification of the seventh embodiment. [Figure 64] FIG. 20 is a diagram illustrating an example of a method of multiplexing a PDCCH for eMBB UE and a slot for URLLC UE, in accordance with a fifth modification of the seventh embodiment. [Figure 65] FIG. 20 is a diagram illustrating an example of a method of multiplexing a PDCCH for eMBB UE and a slot for URLLC UE, in accordance with a fifth modification of the seventh embodiment. [Figure 66] FIG. 13 is a diagram illustrating an example of preempting PDSCH resources when only FL-DMRS is configured in one slot for eMBB UE, according to a sixth modification of the seventh embodiment. [Figure 67] FIG. 13 is a diagram illustrating an example of preempting PUSCH resources when only FL-DMRS is configured in one slot for eMBB UE, according to a sixth modification of the seventh embodiment. [Figure 68] FIG. 20 is a diagram illustrating an example in which a plurality of complementary DMRSs are configured in the UL according to a sixth modification of the seventh embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0058] Embodiment 1 Fig. 2 is a block diagram showing the overall configuration of an LTE communication system 200 being discussed in 3GPP. Fig. 2 will now be described. The radio access network is called E-UTRAN (Evolved Universal Terrestrial Radio Access Network) 201. A mobile terminal device (hereinafter referred to as "mobile terminal (User Equipment: UE)") 202, which is a communication terminal device, is capable of wireless communication with a base station device (hereinafter referred to as "base station (E-UTRAN NodeB: eNB)") 203, and transmits and receives signals via wireless communication.

[0059] Here, the term "communication terminal device" includes not only mobile terminal devices such as mobile cell phone terminal devices, but also stationary devices such as sensors. In the following description, the term "communication terminal device" may be simply referred to as a "communication terminal."

[0060] If control protocols for mobile terminals 202, such as RRC (Radio Resource Control), and user planes (hereinafter sometimes referred to as U-Planes), such as PDCP (Packet Data Convergence Protocol), RLC (Radio Link Control), MAC (Medium Access Control), and PHY (Physical layer), terminate at base stations 203, E-UTRAN is composed of one or more base stations 203.

[0061] The control protocol RRC (Radio Resource Control) between the mobile terminal 202 and the base station 203 performs broadcasting, paging, RRC connection management, etc. The states of the base station 203 and the mobile terminal 202 in RRC include RRC_IDLE and RRC_CONNECTED.

[0062] In RRC_IDLE, PLMN (Public Land Mobile Network) selection, system information (SI) broadcast, paging, cell reselection, mobility, etc. are performed. In RRC_CONNECTED, the mobile terminal has an RRC connection and can transmit and receive data with the network. In addition, in RRC_CONNECTED, handover (HO), measurement of neighbor cells, etc. are performed.

[0063] The base stations 203 are classified into eNBs 207 and Home-eNBs 206. The communication system 200 includes an eNB group 203-1 including a plurality of eNBs 207, and a Home-eNB group 203-2 including a plurality of Home-eNBs 206. A system configured from an EPC (Evolved Packet Core) core network and an E-UTRAN 201 radio access network is called an EPS (Evolved Packet System). The EPC core network and the E-UTRAN 201 radio access network may be collectively referred to as a "network."

[0064] The eNB 207 is connected to a Mobility Management Entity (MME), or a Serving Gateway (S-GW), or an MME / S-GW unit (hereinafter sometimes referred to as an "MME unit") 204 including an MME and an S-GW via an S1 interface, and control information is communicated between the eNB 207 and the MME unit 204. Multiple MME units 204 may be connected to one eNB 207. The eNBs 207 are connected to each other via an X2 interface, and control information is communicated between the eNBs 207.

[0065] The Home-eNB 206 is connected to the MME unit 204 via an S1 interface, and control information is communicated between the Home-eNB 206 and the MME unit 204. A plurality of Home-eNBs 206 are connected to one MME unit 204. Alternatively, the Home-eNB 206 is connected to the MME unit 204 via a Home-eNB GateWay (HeNBGW) 205. The Home-eNB 206 and the HeNBGW 205 are connected via an S1 interface, and the HeNBGW 205 and the MME unit 204 are connected via the S1 interface.

[0066] One or more Home-eNBs 206 are connected to one HeNBGW 205, and information is communicated through an S1 interface. The HeNBGW 205 is connected to one or more MME units 204, and information is communicated through an S1 interface.

[0067] The MME unit 204 and the HeNBGW 205 are upper devices, specifically upper nodes, and control connections between the eNB 207 and the Home-eNB 206, which are base stations, and the mobile terminal (UE) 202. The MME unit 204 constitutes the EPC, which is a core network. The base station 203 and the HeNBGW 205 constitute the E-UTRAN 201.

[0068] Furthermore, 3GPP is considering the following configuration: The X2 interface between Home-eNBs 206 is supported. That is, Home-eNBs 206 are connected via the X2 interface, and control information is communicated between the Home-eNBs 206. From the MME unit 204, HeNBGW 205 appears as Home-eNB 206. From the Home-eNB 206, HeNBGW 205 appears as MME unit 204.

[0069] In either case where the Home-eNB 206 is connected to the MME unit 204 via the HeNBGW 205 or where the Home-eNB 206 is connected directly to the MME unit 204, the interface between the Home-eNB 206 and the MME unit 204 is the same, that is, the S1 interface.

[0070] Base station 203 may configure one cell or multiple cells. Each cell has a predetermined range as coverage, which is the range within which communication with mobile terminal 202 is possible, and performs wireless communication with mobile terminal 202 within the coverage. When one base station 203 configures multiple cells, each cell is configured to be able to communicate with mobile terminal 202.

[0071] FIG. 3 is a block diagram showing the configuration of mobile terminal 202 shown in FIG. 2. The transmission process of mobile terminal 202 shown in FIG. 3 will be described. First, control data from protocol processing unit 301 and user data from application unit 302 are stored in transmission data buffer unit 303. The data stored in transmission data buffer unit 303 is passed to encoder unit 304, where it is subjected to encoding processes such as error correction. Some data may be output directly from transmission data buffer unit 303 to modulation unit 305 without being encoded. The data encoded by encoder unit 304 is modulated by modulation unit 305. The modulated data is converted into a baseband signal, and then output to frequency conversion unit 306, where it is converted into a radio transmission frequency. The transmission signal is then transmitted from antenna 307 to base station 203.

[0072] Furthermore, the reception process of the mobile terminal 202 is performed as follows. A radio signal from the base station 203 is received by the antenna 307. The received signal is converted from a radio reception frequency to a baseband signal by the frequency conversion unit 306, and demodulated by the demodulation unit 308. The demodulated data is passed to the decoder unit 309, where decoding processes such as error correction are performed. Of 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 is controlled by the control unit 310. Therefore, although the control unit 310 is omitted in FIG. 3, it is connected to each of the units 301 to 309.

[0073] Figure 4 is a block diagram showing the configuration of the base station 203 shown in Figure 2. The transmission processing of the base station 203 shown in Figure 4 will be described. The EPC communication unit 401 transmits and receives data between the base station 203 and the EPC (MME unit 204, etc.), the HeNBGW 205, etc. The other base station communication unit 402 transmits and receives data with other base stations. The EPC communication unit 401 and the other base station communication unit 402 each exchange information with a protocol processing unit 403. Control data from the protocol processing unit 403, and user data and control data from the EPC communication unit 401 and the other base station communication unit 402 are stored in a transmission data buffer unit 404.

[0074] The data stored in the transmission data buffer unit 404 is passed to the encoder unit 405, where it undergoes encoding processes such as error correction. Some data may be output directly from the transmission data buffer unit 404 to the modulator unit 406 without undergoing encoding processes. The encoded data is modulated by the modulator unit 406. The modulated data is converted into a baseband signal, and then output to the frequency converter 407, where it is converted into a radio transmission frequency. The transmission signal is then transmitted from the antenna 408 to one or more mobile terminals 202.

[0075] The reception process of the base station 203 is performed as follows: A radio signal from one or more mobile terminals 202 is received by an antenna 408. The received signal is converted from a radio reception frequency to a baseband signal by a frequency conversion unit 407, and demodulated by a demodulation unit 409. The demodulated data is passed to a decoder unit 410, where decoding processes such as error correction are performed. Of the decoded data, control data is passed to a protocol processing unit 403 or an EPC communication unit 401 or an other base station communication unit 402, and 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 a control unit 411. Therefore, although the control unit 411 is omitted in FIG. 4, it is connected to each of the units 401 to 410.

[0076] 5 is a block diagram showing the configuration of an MME. FIG. 5 shows the configuration of an MME 204a included in the MME unit 204 shown in FIG. 2 described above. A PDN GW communication unit 501 transmits and receives data between the MME 204a and a PDN GW. A base station communication unit 502 transmits and receives data via the S1 interface between the MME 204a and a base station 203. If 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 a user plane communication unit 503, and transmitted to one or more base stations 203. If 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 plane communication unit 503, and transmitted to the PDN GW.

[0077] If 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. If 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.

[0078] The HeNBGW communication unit 504 is provided when a HeNBGW 205 is present, and transmits and receives data via an interface (IF) between the MME 204a and the HeNBGW 205 depending on the information type. 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 processing in the control plane control unit 505 is transmitted to the PDN GW via the PDN GW communication unit 501. In addition, the result of processing in the control plane control unit 505 is transmitted to one or more base stations 203 by 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.

[0079] 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 sometimes referred to as the C-Plane). The NAS security unit 505-1 performs security for 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 idle state (also referred to as the LTE-IDLE state or simply idle), generation and control of paging signals in the idle state, addition, deletion, update, and search of tracking areas for one or more mobile terminals 202 under its control, tracking area list management, etc.

[0080] The MME 204a distributes paging signals to one or more base stations 203. The MME 204a also performs mobility control in an idle state. The MME 204a manages a tracking area list when the mobile terminal is in an idle state and an active state. The MME 204a initiates a paging protocol by transmitting a paging message to cells belonging to a tracking area in which the UE is registered. The idle state mobility management unit 505-3 may manage the CSG, CSG ID, and whitelist of the Home-eNB 206 connected to the MME 204a.

[0081] Next, an example of a cell search method in a communication system is shown. Fig. 6 is a flowchart showing an outline of the process from cell search to standby operation performed by a communication terminal (UE) in an LTE communication system. When the communication terminal starts a cell search, in step ST601, it synchronizes slot timing and frame timing using a primary synchronization signal (P-SS) and a secondary synchronization signal (S-SS) transmitted from a surrounding base station.

[0082] P-SS and S-SS are collectively called the Synchronization Signal (SS). The Synchronization Signal (SS) is assigned a synchronization code that corresponds one-to-one to the PCI assigned to each cell. 504 different PCIs are being considered. These 504 different PCIs are used to achieve synchronization and to detect (identify) the PCI of the synchronized cell.

[0083] Next, in step ST602, for the synchronized cell, a cell-specific reference signal (CRS), which is a reference signal (RS) transmitted from the base station for each cell, is detected and the RS received power (Reference Signal Received Power: RSRP) is measured. The RS uses a code that has a one-to-one correspondence with the PCI. By correlating with this code, it is possible to separate the cell from other cells. By deriving the code for the RS of the cell from the PCI identified in step ST601, it is possible to detect the RS and measure the RS received power.

[0084] Next, in step ST603, the cell with the best RS reception quality, for example, the cell with the highest RS reception power, that is, the best cell, is selected from one or more cells detected up to step ST602.

[0085] Next, in step ST604, the PBCH of the best cell is received to obtain the BCCH, which is broadcast information. A MIB (Master Information Block), which includes cell configuration information, is mapped to the BCCH on the PBCH. Therefore, the MIB can be obtained by receiving the PBCH and obtaining the BCCH. Examples of MIB information include the DL (downlink) system bandwidth (also called transmission bandwidth configuration: dl-bandwidth), the number of transmitting antennas, and the SFN (System Frame Number).

[0086] Next, in step ST605, the DL-SCH of the cell is received based on the cell configuration information in the MIB, and SIB (System Information Block) 1 is obtained from the broadcast information BCCH. SIB 1 includes information on access to the cell, information on cell selection, and scheduling information for other SIBs (SIBk; k is an integer greater than or equal to 2). SIB 1 also includes a tracking area code (TAC).

[0087] Next, in step ST606, the communication terminal compares the TAC of the SIB1 received in step ST605 with the TAC portion of the tracking area identity (TAI) in the tracking area list that the communication terminal already holds. The tracking area list is also called a TAI list. The 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 tracking area code number.

[0088] If the comparison in step ST606 shows that the TAC received in step ST605 is the same as the TAC included in the tracking area list, the communication terminal enters standby mode 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 core network (EPC) including an MME, etc., to change the tracking area in order to perform a Tracking Area Update (TAU) through the cell.

[0089] An apparatus constituting a core network (hereinafter sometimes referred to as a "core network side apparatus") updates the tracking area list based on the identification number (e.g., UE-ID) of the communication terminal sent from the communication terminal together with a TAU request signal. The core network side apparatus 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 standby operation in the cell.

[0090] The widespread use of smartphones and tablet devices has led to an explosive increase in cellular wireless communication traffic, raising concerns about a shortage of wireless resources worldwide. In response to this, efforts are being made to develop small cells and promote spatial separation in order to improve frequency utilization efficiency.

[0091] In a conventional cell configuration, a cell configured by an eNB has a relatively wide coverage area. Conventionally, a cell is configured so that a certain area is covered by the relatively wide coverage areas of multiple cells configured by multiple eNBs.

[0092] In the case of small cell configuration, a cell configured by an eNB has a narrower coverage area than a cell configured by a conventional eNB. Therefore, as in the past, a larger number of small cell configuration eNBs are required to cover a certain area compared to conventional eNBs.

[0093] In the following description, a cell with a relatively large coverage, such as a cell configured by a conventional eNB, is referred to as a "macro cell," and an eNB that configures the macro cell is referred to as a "macro eNB." Also, a cell with a relatively small coverage, such as a cell configured as a small cell, is referred to as a "small cell," and an eNB that configures the small cell is referred to as a "small eNB."

[0094] The macro eNB may be, for example, a "Wide Area Base Station" as described in Non-Patent Document 7.

[0095] The small eNB may be, for example, a low-power node, a local area node, a hotspot, etc. Also, the small eNB may be a pico eNB constituting a pico cell, a femto eNB constituting a femto cell, a HeNB, a remote radio head (RRH), a remote radio unit (RRU), a remote radio equipment (RRE), or a relay node (RN). Also, the small eNB may be a "local area base station" or a "home base station" as described in Non-Patent Document 7.

[0096] 7 is a diagram showing the concept of a cell configuration when macro eNBs and small eNBs are mixed. A macro cell configured by a macro eNB has a relatively wide coverage area 701. A small cell configured by a small eNB has a coverage area 702 that is smaller than the coverage area 701 of the macro eNB (macro cell).

[0097] When multiple eNBs are mixed, the coverage of a cell configured by one eNB may be included in the coverage of a cell configured by another eNB. In the cell configuration shown in Figure 7, as indicated by reference numerals "704" and "705," the coverage 702 of a small cell configured by a small eNB may be included in the coverage 701 of a macro cell configured by a macro eNB.

[0098] Also, as indicated by reference numeral "705," the coverage of multiple, for example, two small cells 702 may be included within the coverage of one macro cell 701. A mobile terminal (UE) 703 is included, for example, within the coverage of a small cell 702 and communicates via the small cell.

[0099] Furthermore, in the cell configuration shown in FIG. 7, there may be cases where coverage 701 of a macro cell configured by a macro eNB and coverage 702 of a small cell configured by a small eNB overlap in a complex manner, as indicated by reference numeral "706."

[0100] Also, as indicated by reference numeral "707," there may be cases where coverage 701 of a macro cell configured by a macro eNB and coverage 702 of a small cell configured by a small eNB do not overlap.

[0101] Furthermore, as indicated by reference numeral "708," there may be cases where the coverage 702 of multiple small cells formed by multiple small eNBs is formed within the coverage 701 of one macro cell formed by one macro eNB.

[0102] In uplink transmission using a split bearer using dual connectivity (DC), whether or not to transmit uplink data to a secondary node (SN) (see Non-Patent Document 12) is determined based on the UE's uplink data buffer capacity. The master node (MN) (see Non-Patent Document 12) notifies the UE of an uplink data buffer capacity threshold. The UE compares the uplink data buffer capacity with the threshold, and if the uplink data buffer capacity is equal to or less than the threshold, transmits the uplink data to the MN, and if the uplink data buffer capacity is greater than the threshold, transmits the uplink data to both the MN and the SN.

[0103] However, for example, if the above-mentioned method is applied to uplink data that requires low latency, uplink transmission will be performed to the MN if the uplink data buffer capacity is less than a threshold. For example, if the SN supports a short symbol length (period), uplink transmission must be performed by the MN, even though uplink transmission using the SN would result in low latency characteristics, which causes a problem in that low latency characteristics cannot be obtained.

[0104] Solutions to the aforementioned problems are disclosed below.

[0105] The UE can set which node to transmit uplink to. The MN notifies the UE of information about the uplink transmitting node. The uplink transmitting node can be the MN, the SN, or both the MN and the SN. For example, the identifier of the base station can be used as information about the uplink transmitting node.

[0106] The information of the uplink transmission node may be information of a cell group. The information of the cell group may be information of a master cell group (MCG) and / or a secondary cell group (SCG). The information of the uplink transmission node may be information of a cell, and the information of the cell may be a cell identifier. It indicates the cell used by the UE for uplink transmission.

[0107] In this specification, the communication destination of the UE is mainly expressed as a node or a communication node, but unless otherwise specified, the communication destination of the UE may also be a cell group, a base station, or a cell.

[0108] It is preferable to use RRC signaling to notify information about uplink transmission nodes. For example, information about uplink transmission nodes may be included in an RRC connection reconfiguration message and notified. For example, information about uplink transmission nodes may be notified during DC configuration processing.

[0109] The SN notifies the MN of information for determining which node should be used for uplink transmission from the UE (hereinafter, this information may be referred to as uplink transmission node determination information). The uplink transmission node determination information may be information about delay characteristics. The uplink transmission node determination information may also be information about supported radio settings. The uplink transmission node determination information may also be information about supported communication services. The uplink transmission node determination information may also be information about load conditions or resource usage conditions. The uplink transmission node determination information may also be information about the radio wave propagation environment. The uplink transmission node determination information may be notified using Xn signaling or X2 signaling. For example, the uplink transmission node determination information may be notified during DC setting processing.

[0110] For example, the uplink transmission node determination information may be notified during an SgNB addition process. For example, the uplink transmission node determination information may be included in an SgNB addition request acknowledgement (SgNB Addition Request Acknowledge) and notified. The MN can set the uplink transmission node for the UE when DC is started. Also, for example, the uplink transmission node determination information may be notified during an SgNB modification process. For example, the uplink transmission node determination information may be included in an SgNB modification request acknowledgement (SgNB Modification Request Acknowledge) and notified. When the process is started by a request from the SN, the uplink transmission node determination information may be included in an SgNB modification request notification (SgNB Modification Required) and notified. The MN can set the uplink transmission node for the UE when the SN configuration is changed.

[0111] Seven examples of node determination information for uplink transmission are shown below.

[0112] (1) Sub Carrier Spacing (SCS) supported by the SN. Symbol duration may be used.

[0113] (2) Information on whether the SN supports uplink without grant transmission.

[0114] (3) QoS of communication services supported by the SN. The QoS of an upstream communication service may be used. Information indicating the QoS, such as a QoS profile, QCI, delay time, or packet error loss rate, may also be used.

[0115] (4) RRC configuration of SN.

[0116] (5) SN wireless settings, such as AS settings, MAC settings, and PHY settings.

[0117] (6) Number of symbols in a slot supported by the SN. This may be information on whether or not the SN supports slots with fewer symbols than normal.

[0118] (7) A combination of (1) to (6).

[0119] The MN may determine the uplink transmission node for the UE. By using the uplink transmission node determination information, the MN can determine which node the UE will use for uplink transmission. For example, the MN uses information on the symbol period supported by the SN obtained from the SN to determine a node with a shorter symbol period than its own node as the uplink transmission node for the UE. If the symbol periods are the same, the MN determines both NBs as the uplink transmission nodes for the UE. For example, by performing such a setting for uplink data that requires low latency, the UE can transmit uplink data to a node that supports a shorter symbol period, enabling uplink data to be transmitted with low latency.

[0120] As another example, the MN uses information obtained from the SN as to whether or not no grant transmission is supported to determine a node that supports no grant transmission as the uplink transmission node for the UE. If both nodes support no grant transmission, the MN determines both nodes as the uplink transmission nodes for the UE. For example, by making such a setting for uplink data that requires low latency, the UE can perform no grant transmission without SR, enabling uplink data to be transmitted with low latency.

[0121] The MN may request the SN to notify the uplink transmission node determination information. Xn signaling or X2 signaling may be used to notify the request. For example, the request may be notified during DC setting processing. For example, the request may be notified during SgNB addition processing. For example, the request may be included in an SgNB addition request and notified. The MN can configure an uplink transmission node for the UE when DC starts. Also, for example, the request may be notified during SgNB modification processing. For example, the request may be included in an SgNB modification request and notified. The MN can configure an uplink transmission node for the UE.

[0122] The UE may notify the MN of information for determining which node should be used for uplink transmission from the UE. An example of the uplink transmission node determination information that the UE notifies the MN is the QoS required for the communication service. The uplink transmission node determination information may be the QoS required for the uplink communication service. The uplink transmission node determination information may be information indicating the QoS, such as a QoS profile, QCI, desired delay time, packet error loss rate, etc. It may also include information for identifying the UE. An example of the information for identifying the UE is an identifier.

[0123] RRC signaling may be used to notify the uplink transmission node determination information. For example, the uplink transmission node determination information may be included in a message such as an RRC connection establishment request (RRCConnectionRequest), an RRC connection establishment completion (RRCConnectionSetupComplete), an RRC connection re-establishment request (RRCConnectionReestablishmentRequest), or an RRC connection re-establishment completion (RRCConnectionReestablishmentCcomplete) and notified. By using these example RRC messages, the MN can use the information when setting up DC for the UE.

[0124] The MN may request the UE to notify it of the uplink transmission node determination information. The request may be notified using RRC signaling. For example, the request may be notified by being included in a message such as RRCConnectionSetup or RRCConnectionReestablishment. The MN can then set the uplink transmission node for the UE.

[0125] The CN may notify the MN of information for determining which node should be used for uplink transmission from the UE. Examples of uplink transmission node determination information that the CN notifies the MN include the identifier of the target UE and the QoS required for the uplink communication service of the UE. The uplink transmission node determination information may be the QoS required for the uplink communication service. The uplink transmission node determination information may be information indicating the QoS, such as a QoS profile, QCI, desired delay time, packet error loss rate, etc. S1 signaling or NG-C signaling may be used to notify the information.

[0126] The MN may request the CN to notify it of the uplink transmission node determination information. The request may be notified using S1 signaling or NG-C signaling. The MN can then set the uplink transmission node for the UE.

[0127] FIG. 8 is a diagram showing an example of a sequence in which an MN sets to a UE which node to use for uplink transmission. In the example of FIG. 8, an MgNB is shown as the MN, and an SgNB is shown as the SN. In step ST801, a DC setting process using a split bearer is performed between the UE, the MgNB, and the SgNB. In the example of FIG. 8, a node for uplink data transmission is not set based on the UE's uplink data buffer capacity. In the DC setting process, the MgNB may notify the UE of information indicating a setting method for the uplink transmission node. The information may be notified by RRC signaling. The information may be notified by including it in an RRC connection reconfiguration message. The UE applies the notified setting method. In the example of FIG. 8, the MgNB determines a node for uplink transmission, and notifies the UE of information indicating a method for setting the uplink transmission node.

[0128] Also, the example in FIG. 8 shows a method of determining an uplink transmission node using SCS information of the SgNB. In step ST802, the MgNB requests the SgNB's SCS information. In step ST803, the SgNB notifies the MgNB of the SCS information supported by the SgNB in ​​response to the request from the MgNB. The support information may be for each cell. The SgNB may notify the SCS information supported for each cell. The SCS information may be notified in association with a cell identifier.

[0129] In step ST804, the MgNB compares the SCS supported by itself with the SCS supported by the SgNB, and determines the node that supports the smaller SCS as the uplink transmission node. The example in Fig. 8 shows a case where the SgNB supports a smaller SCS than the MgNB. The MgNB determines the SgNB as the uplink transmission node.

[0130] At this time, the MgNB may use QoS information of the communication service of the UE that has been acquired in advance. The MgNB may acquire the QoS information of the communication service from the CN or may acquire it from the UE. The QoS information of the communication service may be notified from the CN to the MgNB during bearer setup processing for the communication service of the UE. The QoS information of the communication service may be included in bearer information for performing the DC setup processing.

[0131] The MgNB may determine a node that supports a smaller SCS as the uplink transmission node so as to satisfy the QoS. For example, if low latency characteristics are required for the UE's communication service, the MgNB may determine an SgNB that supports a smaller SCS as the uplink transmission node. In step ST805, the MgNB notifies the UE of information about the SgNB determined as the uplink transmission node.

[0132] The information about the SgNB includes node information, base station information, cell group information, cell information, etc. The MgNB notifies the UE of this information for identifying the SgNB in ​​association with information indicating that the SgNB has been selected as the uplink transmission node.

[0133] In step ST806, the UE starts uplink transmission processing to the SgNB, which is the uplink transmission node notified by the MgNB. When uplink data occurs in the UE, the UE transmits an SR to the SgNB in ​​step ST807. The SR settings at the MgNB and SgNB may be notified to the UE by the MgNB in ​​the DC setting processing. If cell information for uplink transmission has been notified by the MgNB in ​​step ST805, the UE may transmit an SR to that cell.

[0134] In step ST808, the SgNB notifies the UE of a grant for uplink communication (uplink scheduling information). In step ST809, the UE transmits uplink data to the SgNB in ​​accordance with the uplink grant. The UE may also notify a BSR (Buffer Status Report). Thereafter, the processes of steps ST808 and ST809 are repeated until there is no more uplink data, thereby transmitting the uplink data.

[0135] In this way, in DC, the UE can transmit uplink data to the SgNB that the MgNB has set as the uplink transmitting node, regardless of the uplink data buffer capacity. For example, when uplink data requiring low latency occurs, even if the amount of data is small, the UE can transmit the uplink data to the SgNB that supports a smaller SCS. In DC, it is possible to achieve lower latency.

[0136] The above describes a method in which the MN notifies the UE of information about the uplink transmission node. Another method will now be described. The MN may notify the UE of information for determining the uplink transmission node.

[0137] RRC signaling may be used to notify information for the UE to determine an uplink transmission node. For example, the information may be included in an RRC connection reconfiguration message and notified. For example, the information may be notified during a DC setting process.

[0138] Seven examples of information for the UE to determine the uplink transmission node are shown below.

[0139] (1) Sub Carrier Spacing (SCS) supported by each node. Symbol duration may be used.

[0140] (2) Information on whether each node supports upstream transmission without grant.

[0141] (3) QoS of communication services supported by each node. The QoS of the upstream communication service may be used. Information indicating the QoS, such as the QoS profile, QCI, delay time, and packet error loss rate, may also be used.

[0142] (4) RRC configuration of each node.

[0143] (5) Wireless settings of each node, such as AS settings, MAC settings, and PHY settings.

[0144] (6) Number of symbols in a slot supported by the SN. This may be information on whether or not the SN supports slots with fewer symbols than normal.

[0145] (7) A combination of (1) to (6).

[0146] These pieces of information may be associated with MN or SN, making it possible to identify whether the pieces of information are information about MN or SN. Furthermore, these pieces of information may be associated with each node. For example, these pieces of information may be associated with a base station identifier, making it possible to identify which node or base station this information is information about. Furthermore, these pieces of information may be associated with each cell group. These pieces of information may be associated with MCG or SCG, making it possible to identify whether the pieces of information are information about MCG or SCG. Furthermore, these pieces of information may be associated with a cell. For example, these pieces of information may be associated with a cell identifier, making it possible to identify which cell this information is information about.

[0147] The SN may notify the UE of information for the UE to determine the uplink transmission node. This notification may be made using RRC signaling. For example, the notification may be included in an RRCConnectionReconfiguration message.

[0148] The information notified from the SN to the UE may be information for the UE of each node to determine the uplink transmission node. Information for the UE of the MN to determine the uplink transmission node may be notified from the MN to the SN. The SN notifies the UE of information for the MN and the UE of its own node to determine the uplink transmission node. In this way, even if the radio environment of the MN is poor, it is possible to set the uplink transmission node using the SN, and low latency characteristics can be obtained.

[0149] The information notified from the SN to the UE may be information for the UE of the SN to determine the uplink transmission node. Information for the UE of the MN to determine the uplink transmission node may be notified from the MN to the UE. In this way, it becomes possible to eliminate the need for communication between the MN and the SN. By notifying the UE of this information from each node, it becomes possible to reflect the status of each node in a timely manner.

[0150] The UE may determine the uplink transmission node. By using information for determining the uplink transmission node, the UE can determine which node to transmit to for uplink transmission. For example, the MN notifies the UE of information on the symbol periods supported by each of the MN and SN. The UE uses the information on the symbol periods supported by each node to determine the node that supports the shorter symbol period as the UE's uplink transmission node. If the symbol periods are the same, the UE determines both NBs as the UE's uplink transmission nodes. For example, by performing such a setting for uplink data that requires low latency, the UE can transmit uplink data to a node that supports the shorter symbol period, enabling uplink data to be transmitted with low latency.

[0151] As another example, the UE uses information indicating whether each node supports no-grant transmission to determine a node that supports no-grant transmission as the UE's uplink transmission node. If both nodes support no-grant transmission, the UE determines both nodes as the UE's uplink transmission nodes. For example, by performing such a setting for uplink data that requires low latency, the UE can perform no-grant transmission without SR, enabling the UE to transmit uplink data with low latency.

[0152] As another example, the UE uses information on the delay times supported by each node to determine the node that supports the shorter delay time as the node for uplink transmission for the UE. If the delay times are the same, the UE determines both nodes as the node for uplink transmission for the UE. For example, by performing such a setting for uplink data that requires low delay characteristics, the UE can transmit uplink data with low delay.

[0153] The UE may use the QoS required for the communication service to determine the uplink transmission node. The UE may use the QoS required for the uplink communication service. The UE may use information indicating the QoS, such as a QoS profile, QCI, desired delay time, packet error loss rate, etc. For example, the UE uses information on the delay time supported by each node to determine a node that supports a delay time shorter than the desired delay time as the uplink transmission node for the UE. For example, by making such a setting for uplink data that requires low delay characteristics, the UE can transmit uplink data with low delay.

[0154] The method by which the UE determines the uplink transmission node may be determined by the UE depending on the uplink communication service, or the method by which the UE determines the uplink transmission node may be statically determined in advance by a standard or the like.

[0155] It has been disclosed that the MN notifies the UE of information for the UE to determine the uplink transmission node. As a method for the MN to obtain information on the SN from the information, it is preferable to apply the method described above in which the MN obtains examples of information for determining the uplink transmission node from the SN.

[0156] Figure 9 shows an example of a sequence in which a UE determines an uplink transmission node. The sequence shown in Figure 9 includes the same steps as the sequence shown in Figure 8, so the same steps are given the same step numbers and common explanations are omitted. In step ST901, a DC setting process is performed. In the example of Figure 9, in the DC setting process, information indicating a method by which the UE determines an uplink transmission node is notified to the UE. Also, the example of Figure 9 shows a method of determining an uplink transmission node using SCS information of the SgNB, as in Figure 8.

[0157] In step ST902, the MgNB notifies the UE of information for determining an uplink transmission node. The MgNB notifies the UE of SCS information supported by the MgNB itself and SCS information supported by the SgNB. The MgNB notifies the UE of information for identifying the SgNB, in association with information indicating that the SgNB is a candidate for an uplink transmission node. The information for identifying the SgNB is, for example, node information, base station information, cell group information, or cell information.

[0158] In step ST903, the UE determines the node that supports the smaller SCS as the uplink transmission node. The example in Fig. 9 shows a case where the SgNB supports a smaller SCS than the MgNB. The UE determines the SgNB as the uplink transmission node.

[0159] In this case, the UE may use QoS information of the communication service for which DC is set. The UE may determine a node that supports a smaller SCS as the uplink transmission node so as to satisfy the QoS. For example, if low latency characteristics are required for the UE's communication service, the UE may determine an SgNB that supports a smaller SCS as the uplink transmission node.

[0160] In step ST806, the UE starts uplink transmission processing to the SgNB that has been determined as the uplink transmission node. When uplink data occurs in the UE, the UE transmits the uplink data to the SgNB in ​​steps ST807 to ST809.

[0161] In this way, in DC, the UE can transmit uplink data to the SgNB set as the uplink transmitting node regardless of the uplink data buffer capacity. For example, when uplink data requiring low latency occurs, even if the amount of data is small, the UE can transmit the uplink data to an SgNB that supports a smaller SCS. In DC, it is possible to achieve lower latency.

[0162] The above describes a method in which the MN notifies the UE of information for determining the uplink transmission node. Another method is now disclosed. The MN notifies the UE of a threshold for determining the uplink transmission node. The MN notifies the UE of a threshold that is an index different from the uplink data buffer capacity in the UE as the threshold for determining the uplink transmission node. The UE uses this threshold to determine the uplink transmission node.

[0163] It is preferable to use RRC signaling to notify the threshold for determining the node for uplink transmission. For example, the threshold may be included in an RRCConnectionReconfiguration message and notified. For example, the threshold may be notified during DC setting processing. The MN may notify information about the node to be used for uplink transmission when the above-mentioned indicator is smaller than the threshold (may be equal to or smaller than the threshold), and information about the node to be used for uplink transmission when the above-mentioned indicator is equal to or larger than the threshold (may be larger than the threshold). This makes it possible to flexibly set the node to be used for uplink transmission.

[0164] As another method, the node to be used for uplink transmission when the aforementioned indicator is smaller than a threshold value, and the node to be used for uplink transmission when the aforementioned indicator is equal to or greater than a threshold value may be statically determined in advance by a standard, etc. This reduces the amount of information required for notification.

[0165] When the above-mentioned indicator is less than the threshold or greater than or equal to the threshold, the node used for uplink transmission may be the MN, or the SN, or both the MN and the SN. Furthermore, the information on the uplink transmission node may be the identifier of the base station. The information on the uplink transmission node may be the information on the cell group. The information on the cell group may be the information on the master cell group (MCG) or the secondary cell group (SCG). The information on the uplink transmission node may be the information on the cell, which may be the cell identifier. Indicates the cell used by the UE for uplink transmission.

[0166] The threshold index used by the UE to determine the uplink transmission node may be, for example, information indicating the QoS of the uplink communication service. The index may be, for example, a desired delay time of the uplink communication service. The index may also be, for example, a desired packet error loss rate of the uplink communication service. By using the index required for the uplink communication service, the MN can set the uplink transmission node for obtaining the desired QoS for the UE.

[0167] For example, the MN notifies the UE of a threshold value for the desired delay time of an uplink communication service, information indicating that the SN will be used as the uplink transmitting node if the desired delay time is smaller than the threshold value, and information indicating that the MN will be used as the uplink transmitting node if the desired delay time is equal to or greater than the threshold value. The UE transmits uplink data to the SN if the desired delay time of the uplink data is smaller than the threshold value, and transmits uplink data to the MN if the desired delay time is equal to or greater than the threshold value. For example, by making such settings for uplink data that requires low delay characteristics, the UE can transmit uplink data with low delay.

[0168] 10 and 11 show an example of a sequence in which a UE determines an uplink transmission node using a threshold value. In FIGS. 10 and 11, an example is shown in which the threshold value is used as an index for a desired delay time. FIGS. 10 and 11 are connected at the position of a boundary line BL1011. The sequences shown in FIGS. 10 and 11 include the same steps as the sequence shown in FIG. 8, and therefore the same steps are assigned the same step numbers, and common explanations will be omitted. In step ST1000, a DC setting process is performed. In the examples of FIGS. 10 and 11, information indicating a method in which the UE determines an uplink transmission node using a threshold value in the DC setting process is notified to the UE.

[0169] In step ST1001, the MgNB notifies the UE of a desired delay time threshold as a threshold for determining a node for uplink transmission. Along with this notification, the MgNB notifies the UE of information on the node to be used for uplink transmission when the desired delay time is smaller than the threshold, and information on the node to be used for uplink transmission when the desired delay time is equal to or greater than the threshold. In the examples of Figures 10 and 11, it is assumed that the SgNB is used for uplink transmission when the desired delay time is smaller than the threshold, and that both the MgNB and the SgNB are used for uplink transmission when the desired delay time is equal to or greater than the threshold. The MgNB determines these nodes using the SCS information acquired from the SgNB in ​​steps ST802 and ST803.

[0170] In step ST1002, the UE determines whether the desired delay time of the uplink communication service is smaller than the threshold notified by the MgNB. If the UE determines that the desired delay time is smaller than the threshold, in step ST1003, the UE decides to transmit uplink data to the SgNB in ​​accordance with the node information notified by the MgNB in ​​the above-mentioned step ST1001. When uplink data is generated in the UE, in steps ST1004 to ST1006, the UE transmits the uplink data to the SgNB.

[0171] On the other hand, if the UE determines in step ST1002 that the desired delay time is equal to or greater than the threshold, the UE decides in step ST1007 to transmit uplink data to both the MgNB and the SgNB in ​​accordance with the node information notified by the MgNB in ​​the above-mentioned step ST1001. When uplink data occurs in the UE, the UE transmits the uplink data to the MgNB in ​​steps ST1008 to ST1010, and transmits the uplink data to the SgNB in ​​steps ST1011 to ST1013.

[0172] In this way, in DC, the UE can transmit uplink data to the node set as the uplink transmitting node regardless of the uplink data buffer capacity. For example, when uplink data requiring low latency occurs, even if the amount of data is small, the UE can transmit the uplink data to an SgNB that supports a smaller SCS. In DC, it is possible to achieve lower latency.

[0173] Multiple thresholds may be used. The MN notifies the UE of multiple thresholds for determining the node for uplink transmission. The UE uses the multiple thresholds to determine the node for uplink transmission. For example, the thresholds for a predetermined index may be T1 and T2. The MN may notify information on the node to be used for uplink transmission when the predetermined index of the uplink data is smaller than T1, the node to be used for uplink transmission when the index is greater than or equal to T1 and less than T2, and the node to be used for uplink transmission when the index is greater than or equal to T2. This makes it possible to flexibly set the node to be used for uplink transmission. As mentioned above, these nodes may be statically determined in advance by standards, etc. The amount of information required for notification is small.

[0174] As an alternative to using multiple thresholds, one threshold may be set for each of multiple indicators. Thresholds for multiple indicators may be set in combination. Multiple indicators can be used to determine the uplink transmitting node.

[0175] As an alternative to using multiple thresholds, multiple indicators may be set to provide hysteresis, which can reduce the occurrence of a situation where the node performing uplink transmission alternates in a short period of time.

[0176] Although it has been disclosed that the MN notifies the UE of a threshold for determining the uplink transmission node, it is preferable that the threshold be determined by the MN. This allows the threshold to be set flexibly according to the load situation at the MN and the characteristics required for the communication service. As an alternative, the threshold may be determined by the CN and notified to the MN. The MN notifies the UE of the threshold. This allows the threshold to be set flexibly taking into account the situations of multiple nodes under the CN. Furthermore, it is possible to reduce the amount of processing at the MN for determining the threshold.

[0177] The threshold may be statically determined by a standard or the like. This makes it possible to reduce signaling for notification from the MN to the UE. When multiple thresholds are used, numbers may be assigned to the thresholds. The MN notifies the UE of the number, allowing the UE to recognize the threshold corresponding to the number. In addition, an index may be associated with the threshold. For example, the MN notifies the UE of the index, allowing the UE to recognize the threshold determined by a standard or the like.

[0178] A method for changing the setting will be disclosed. Although the method for the MN to notify the UE of information about the uplink transmission node has been disclosed, the MN may change the uplink transmission node and notify the UE of information about the changed uplink transmission node. The UE transmits uplink data to the uplink transmission node using the newly notified information about the changed uplink transmission node.

[0179] Although the method in which the MN notifies the UE of information for determining the uplink transmission node has been disclosed, the MN may change the information for determining the uplink transmission node and notify the UE of the changed information. The UE determines the uplink transmission node using the newly notified changed information for determining the uplink transmission node.

[0180] Although the method in which the MN notifies the UE of the threshold for determining the uplink transmission node has been disclosed, the MN may change the threshold for determining the uplink transmission node and notify the UE of the changed threshold. The UE determines the uplink transmission node using the newly notified changed threshold for determining the uplink transmission node.

[0181] In cases where the CN determines the threshold, the CN may change the threshold and notify the MN of the changed threshold, which in turn notifies the UE of the threshold.

[0182] This allows the settings to be changed. By changing the settings according to the load status of the MN or SN, changes in the wireless environment, etc., it becomes possible to set a more suitable uplink transmission node according to the change in the situation.

[0183] The above-mentioned configuration methods may be configurable. The MN may decide which configuration method to use, and notify the UE of information indicating the configuration method. The CN may decide which configuration method to use, and notify the MN of information indicating the configuration method. The MN notifies the UE of information indicating the configuration method notified by the CN. If the MN wants to change the configuration method, it may notify the UE of the new configuration method to be used. The UE will apply the newly notified changed configuration method.

[0184] In this way, it becomes possible to set up a more suitable uplink transmission node in response to changes in the situation. It is also possible to indicate which method to set by notifying the information used for each setting method, rather than explicitly notifying the setting method. This makes it possible to reduce the amount of information required for notification.

[0185] The above-mentioned method can also be applied to MC (multi connectivity) as appropriate. Two or more SNs can be used. When a UE is connected to one MN and two or more SNs, it is possible to set an uplink transmission node from among those nodes.

[0186] The above-mentioned method can be applied to a split bearer. That is, the above-mentioned method can be applied not only to an MCG split bearer but also to an SCG split bearer. In addition, in the case of an SCG split bearer, the SN may determine the base station for uplink transmission.

[0187] Some or all of the above-described methods may be combined as appropriate. For example, notification of a threshold for determining an uplink transmission node and notification of information for determining an uplink transmission node may be combined. The UE may determine an uplink transmission node when a predetermined indicator is smaller than a threshold, and an uplink transmission node when the predetermined indicator is equal to or greater than the threshold, using information for determining an uplink transmission node. In this way, the UE can perform uplink transmission to a node that is more suitable depending on the situation of each node, rather than performing uplink transmission to a node that has been notified or determined in advance.

[0188] Some or all of the above methods may be combined as appropriate, including the method of determining to which node uplink data is to be transmitted based on the amount of uplink data buffered in the UE. For example, if the buffer capacity value is smaller than a threshold, a specific node is selected as the uplink transmission node, and if the buffer capacity value is equal to or greater than the threshold, a node that supports a shorter symbol period is selected as the uplink transmission node. If the uplink data capacity is small, even if there is a slight delay, the amount of delay until uplink data transmission is completed will not be large.

[0189] The method disclosed in the first embodiment makes it possible to set a node to which uplink data from a UE is to be transmitted. Also, it makes it possible to set a node to which uplink data from a UE is to be transmitted, depending on the frame configuration and functions supported by each node. It becomes possible to transmit uplink data to the most optimal node depending on the status of each node, and it becomes possible to obtain the QoS required for the communication service.

[0190] For example, a UE can transmit data that requires low latency via a node that has low latency, regardless of the amount of data. In this way, the latency of uplink data transmission can be reduced.

[0191] NR requires support for URLLC (Ultra Reliable Low Latency Communication). A split bearer may be supported for the URLLC service. A split bearer may be supported in the DRB for the URLLC service. By using a split bearer, it is possible to improve throughput. Furthermore, the method disclosed in the first embodiment may be applied to the URLLC service. By applying the method disclosed in the first embodiment to the URLLC service, it is possible to obtain low latency characteristics even when using a split bearer.

[0192] In this way, it is possible to configure a split bearer for communication services that require low latency, thereby improving the throughput of low latency communications, and as a result, achieving even lower latency.

[0193] Variation 1 of Embodiment 1 When transmitting uplink data using an SN, the UE must receive an uplink scheduling grant (sometimes simply called a grant) for transmitting uplink data from the SN. To obtain an uplink grant from the SN, the UE must first transmit an SR to the SN. The SR is transmitted at a preset periodic timing. For this reason, even if uplink data is generated, the uplink data cannot be transmitted immediately and must wait for the timing of the next SR transmission.

[0194] As described above, multiple processes must be performed from the generation of uplink data to the SN until the uplink data is transmitted by the SN, resulting in a large delay. For this reason, even if the method disclosed in the first embodiment is applied to a communication service that requires low delay, and it becomes possible to set up uplink data transmission using the SN, a large delay will occur before the uplink data is actually transmitted to the SN.

[0195] Solutions to the aforementioned problems are disclosed below.

[0196] The SN performs transmission without grant. The SN is allowed to configure transmission without grant. In other words, the SN supports transmission without grant. One or more cells of the SN may support transmission without grant. In DC using an SCG bearer, the SN may support transmission without grant.

[0197] No-grant transmission is an UL transmission without SR and the first grant, where the no-grant transmission configuration is based only on the RRC configuration. Hereinafter, this may be referred to as the first no-grant transmission. Examples of RRC configuration include allocation of time-frequency resources for UL transmission, UE-specific DMRS configuration, and the number of repetitions. Another method of no-grant transmission is UL transmission without grant, where the no-grant transmission configuration is based on both the RRC configuration and L1 signaling. Hereinafter, this may be referred to as the second no-grant transmission. Examples of RRC configuration include the resource cycle for UL transmission and information related to power control. Examples of L1 configuration include allocation of time-frequency resources for UL transmission and information for activating / deactivating (hereinafter sometimes referred to as "act / deact") uplink data transmission.

[0198] In this way, by enabling the SN to transmit no grant, it is possible to eliminate the need for the SN to receive an SR and subsequently transmit an uplink grant, thereby reducing the delay time of uplink data transmission in the SN.

[0199] In DC using split bearer, SN may support no grant transmission, and the same effect can be achieved.

[0200] A method for enabling SN to transmit no grant is disclosed. The setting for no grant transmission is performed by RRC. For this reason, RRC signaling is required. However, in DC, the RRC signaling must be notified from the MN to the UE. There is a problem in that the SN cannot notify the UE of the RRC setting for SN's no grant transmission.

[0201] Solutions to the aforementioned problems are disclosed below.

[0202] The SN decides not to transmit a grant. The SN performs RRC configuration for no grant transmission. The SN notifies the MN of its own node's RRC configuration for no grant transmission. The SN may notify information for identifying its own node. The SN's RRC configuration for no grant transmission may be notified in association with information for identifying its own node. An example of information for identifying its own node is an identifier. The SN may notify the MN of information for identifying the UE for which the SN will perform the RRC configuration for no grant transmission. The SN's RRC configuration for no grant transmission may be notified in association with information for identifying the UE. An example of information for identifying the UE is an identifier. X2 or Xn signaling may be used for notification from the SN to the MN.

[0203] The MN notifies the UE of the RRC configuration of the SN received from the SN. Information for identifying the SN may also be notified. By notifying the MN of the RRC configuration for no grant transmission set by the SN once, it becomes possible for the SN to notify the UE of the RRC configuration for no grant transmission in the DC. The UE becomes able to receive the RRC configuration for no grant transmission of the SN. The UE becomes able to transmit no grant to the SN using the RRC configuration for no grant transmission of the SN.

[0204] Figures 12 and 13 show an example of a sequence in which an SN transmits no grant in a split bearer. Figures 12 and 13 are connected at the boundary line BL1213. Figures 12 and 13 show the first no grant transmission. The sequence shown in Figures 12 and 13 includes the same steps as the sequence shown in Figure 8, so the same step numbers are used for the same steps and common explanations will be omitted.

[0205] In steps ST801 to ST809, in DC, the UE transmits uplink data to the SgNB. In step ST1101, the SgNB decides not to transmit a grant to the UE. For example, the SgNB may decide not to transmit a grant in consideration of information about the bearer notified by the MgNB in ​​the DC setting process, the load situation at the SgNB, the usage situation of radio resources, and the like. For example, if the throughput of uplink data communication on the bearer of the UE does not satisfy the requirement and there are spare radio resources at the SgNB, the SgNB decides not to transmit a grant to the UE.

[0206] The SgNB that has decided not to transmit a grant to the UE in Step ST1101 described above configures the UE for no grant transmission in Step ST1102. In Step ST1103, the SgNB notifies the MgNB of the configuration for no grant transmission. The SgNB notifies the MgNB of the configuration for no grant transmission, in association with information that identifies the UE for which the configuration for no grant transmission is to be performed, for example, the UE identifier. In Step ST1104, the MgNB notifies the UE of the SgNB's configuration for no grant transmission.

[0207] In Step ST1105, the UE configures the SgNB for no grant transmission. When uplink data occurs in the UE, the UE transmits the uplink data to the SgNB in ​​Step ST1106 using the SgNB's configuration for no grant transmission received in the above-mentioned Step ST1104 without transmitting an SR to the SgNB. The UE may also transmit a BSR.

[0208] In step ST1107, the SgNB that has received the BSR transmits an uplink grant to the UE. In step ST1108, the UE transmits uplink data to the SgNB in ​​accordance with the received uplink grant. The UE may also transmit a BSR. In this way, uplink data transmission is performed between the UE and the SgNB.

[0209] By doing this, in DC, the UE can receive the grant no transmission setting of the SgNB. The UE can perform grant no transmission to the SgNB using the grant no transmission setting of the SgNB. Since SR and the accompanying first uplink grant transmission can be eliminated, it is possible to achieve lower delay in uplink communication.

[0210] This section discloses a case where some of the settings for no grant transmission are configured by RRC and the rest are configured by L1, as in the second case of no grant transmission. The MN may notify the UE of the RRC settings and L1 settings for no grant transmission of the SN. The MN may notify the UE of the RRC settings of the SN by RRC signaling and the L1 settings by L1 signaling. The L1 signaling may be included in the DCI sent from the MN to the UE for notification.

[0211] The SN's RRC settings and L1 settings for no grant transmission may be notified from the SN to the MN before the MN notifies the UE. The SN may notify information for identifying the own node. The SN may notify the MN of information for identifying the UE for which the no grant transmission setting is to be performed. The SN's RRC settings and L1 settings for no grant transmission may be notified in association with information for identifying the UE. X2 or Xn signaling may be used for notification from the SN to the MN. X2 or Xn signaling may be used for notification from the SN to the MN.

[0212] In this way, in the case of a second non-transmission of grant, it is possible for the SN to notify the UE of the RRC configuration and L1 configuration of non-transmission of grant in the DC. The UE can receive the RRC configuration and L1 configuration of non-transmission of grant from the SN. The UE can perform non-transmission of grant to the SN using the RRC configuration and L1 configuration of non-transmission of grant from the SN.

[0213] Another method for the second case of no grant transmission is disclosed. The SN may notify the UE of its L1 setting of no grant transmission. The MN may notify the UE of the RRC setting of no grant transmission by RRC signaling, and the SN may notify the UE of the L1 setting of no grant transmission by L1 signaling. The L1 signaling may be included in DCI sent from the SN to the UE for notification.

[0214] The RRC setting of the SN not to transmit a grant may be notified from the SN to the MN before the MN notifies the UE. The notification from the SN to the MN may be made using X2 or Xn signaling.

[0215] By doing so, it is no longer necessary to notify the SN of its L1 setting of no grant transmission via the MN. This makes it possible to reduce the delay time required for Xn or X2 signaling from the SN to the MN and the processing delay time that occurs when the MN is heavily loaded. It also makes it possible to execute L1 setting from the SN to the UE with low delay. For example, it becomes possible to execute act / deact of no grant transmission from the SN to the UE in a timely manner with low delay.

[0216] Figures 14 and 15 show an example of a sequence in which an SN transmits no grant in a split bearer. Figures 14 and 15 are connected at the boundary line BL1415. Figures 14 and 15 show a second no grant transmission. The sequences shown in Figures 14 and 15 include the same steps as the sequences shown in Figures 12 and 13, so the same step numbers are used for the same steps and common explanations will be omitted.

[0217] The UE that configured the SgNB for no grant transmission in Step ST1105 receives L1 signaling from the SgNB. In Step ST1201, the SgNB notifies the UE of the L1 configuration for no grant transmission using L1 signaling. A physical dedicated control channel in which the L1 configuration is included in DCI may be used as the L1 signaling. When uplink data occurs in the UE, the UE does not transmit an SR to the SgNB, but transmits the uplink data to the SgNB in ​​Step ST1106 using the SgNB configuration for no grant transmission received in Step ST1104 and the SgNB configuration for no grant transmission received in Step ST1201. The UE may also transmit a BSR.

[0218] In step ST1107, the SgNB that has received the BSR transmits an uplink grant to the UE. In step ST1108, the UE transmits uplink data to the SgNB in ​​accordance with the received uplink grant. The UE may also transmit a BSR. In this way, uplink data transmission is performed between the UE and the SgNB.

[0219] By doing this, in DC, the UE can receive both the RRC configuration and L1 configuration of the SgNB's grant non-transmission. The UE can perform grant non-transmission to the SgNB using these SgNB grant non-transmission configurations. Since SR and the associated initial uplink grant transmission can be eliminated, it is possible to achieve lower delay in uplink communication.

[0220] In the above-mentioned method, the RRC setting of the SN for no grant transmission is notified to the UE via the MN. Another method is disclosed. The SN may notify the UE of the RRC setting of the SN for no grant transmission. This reduces the delay time required for Xn or X2 signaling from the SN to the MN and the processing delay time that occurs when the MN is heavily loaded. This allows the UE to quickly execute no grant transmission to the SN.

[0221] The SN may notify both the UE and the MN of the RRC setting of the SN for no grant transmission, so that the MN can recognize the RRC setting of the SN for no grant transmission.

[0222] The SN may notify the UE of some or all of the RRC settings for no grant transmission of the SN. For example, parameters that need to be coordinated between the MN and the SN are notified to the UE via the MN, and parameters that do not need to be coordinated between the MN and the SN are notified to the UE from the SN.

[0223] For example, the power setting information for uplink data transmission without grant transmission may be notified from the SN to the MN, and then from the MN to the UE. For example, in the case of a split bearer, the MN can recognize the uplink data transmission power setting information of the SN, so the MN can adjust the transmission power to the MN and the transmission power to the SN. For example, the transmission power to the MN can be set according to the transmission power that the UE can transmit.

[0224] The MN may perform coordination with the SN. In response to the RRC configuration received from the SN, the MN may notify the SN of a request to change the RRC configuration. The notification may include the RRC configuration requested by the MN. The SN changes the configuration and notifies the MN of the result. For example, the MN notifies the SN of a desired transmission power setting to ensure the power required for transmission from the UE to the MN. The SN sets uplink transmission power without grant transmission according to the desired transmission power and notifies the MN of the setting.

[0225] The MN notifies the UE of the RRC settings resulting from the adjustment made with the SN. In this way, the MN is able to make adjustments between the MN and the SN.

[0226] A method for changing the settings is disclosed. The SN notifies the MN of the RRC settings after the change to no grant transmission of the SN. The SN may notify the RRC settings and L1 settings. The SN may notify information for identifying the own node. The SN may notify information about the UE for which the setting for no grant transmission is to be changed. The changed settings may be notified in association with information about the UE for which the setting for no grant transmission is to be changed. The MN notifies the UE of the RRC settings after the change to no grant transmission of the SN. The MN notifies the RRC settings and L1 settings. The RRC settings and L1 settings may be changed at the same time or at different times. This makes the settings more flexible. Alternatively, the SN may notify the MN of only the changed settings or setting parameters.

[0227] The UE changes only the notified settings or configuration parameters. This reduces the amount of signaling or information required for notification. The UE can then perform grant no-transmission to the SN using the newly notified changed RRC settings and / or L1 settings for grant no-transmission from the SN.

[0228] The SN may notify the UE of the L1 settings after the SN has changed the grant non-transmission. The SN may notify the RRC settings and the L1 settings. The RRC settings and the L1 settings may be changed at the same time or at different times. This makes the settings more flexible. Alternatively, the SN may notify the UE of only the changed settings or setting parameters. The UE changes only the notified settings or setting parameters. This reduces the amount of signaling or information required for notification.

[0229] The UE can then perform no grant transmission to the SN using the newly notified changed RRC configuration and / or L1 configuration regarding no grant transmission to the SN.

[0230] A method for canceling the setting is disclosed. The SN notifies the MN of the cancellation of the SN's no-grant transmission setting. The SN may notify information for identifying its own node. The SN may notify information about the UE that will cancel the no-grant transmission setting. The cancellation of the SN's no-grant transmission setting may be notified in association with information about the UE that will cancel the no-grant transmission setting. The MN notifies the UE of the cancellation of the SN's no-grant transmission setting. The UE that receives the cancellation notification cancels the no-grant transmission setting to the SN. The SN may notify the UE of the cancellation of the SN's no-grant transmission setting. The UE that receives the cancellation notification cancels the no-grant transmission setting to the SN.

[0231] The MN may request the SN to configure the SN to transmit no grant. The MN may also notify the SN of configuration information for no grant transmission that it requests the SN to transmit. The MN may also notify the SN of information for identifying the own node. The MN may also notify the SN of information for identifying the UE for which no grant transmission is to be configured. The request for the configuration of no grant transmission may be notified in association with information for identifying the UE for which no grant transmission is to be configured. Xn signaling or X2 signaling may be used to notify the request.

[0232] The configuration information for no grant transmission may be RRC configuration parameters, L1 configuration parameters, or both RRC configuration parameters and L1 configuration parameters. The configuration information for no grant transmission may be part or all of the configuration parameters for no grant transmission. The configuration information for no grant transmission may be information indicating whether the first grant is to be transmitted or the second grant is to be transmitted. The configuration information for no grant transmission requested from the SN may be the no grant transmission configuration that the MN has configured for itself.

[0233] The requests to the SN can be flexibly set. For example, it is possible to request more appropriate settings depending on the load situation of the MN and the radio wave propagation environment between the MN and the UE.

[0234] In response to the grant no transmission setting request notified by the MN, the SN determines the grant no transmission setting for the target UE at its own node. The grant no transmission setting may be set by the SN. Alternatively, the grant no transmission setting information notified by the MN may be used. By using the grant no transmission setting information requested by the MN, the setting can be made taking into account the load situation of the MN, the radio wave propagation environment between the MN and the UE, etc.

[0235] The SN may set the setting information for no grant transmission that is not notified from the MN. This enables the setting required for no grant transmission to be performed, and enables no grant transmission to be performed for the UE.

[0236] The UE may notify the SN of information indicating the QoS required for the communication service. The UE may notify the SN of information indicating the QoS required for the uplink communication service. The UE may notify the SN of information for identifying the UE. The information may be notified from the UE to the MN, and then from the MN to the SN.

[0237] As another method, the SN may derive information indicating the QoS required for the uplink communication service using information indicating the QoS required for the downlink communication service. For example, the information indicating the QoS required for the downlink communication service may be set to information indicating the QoS required for the uplink communication service corresponding to the downlink communication service. In this way, it is possible to reduce the signaling required for notifying the SN of the information indicating the QoS from the UE.

[0238] The SN can use this information to determine whether to set up no grant transmission in its own node. For example, the SN determines whether to set up no grant transmission for the UE based on the desired delay time required for the UE's uplink communication service and the load status of its own node, such as the amount of unused resources.

[0239] For example, if the amount of unused resources is greater than a predetermined value, the SN sets the UE to not transmit a grant. If the amount of unused resources is less than a predetermined value and the desired delay time is shorter than a predetermined time, the SN sets the UE to not transmit a grant. If the amount of unused resources is less than a predetermined value and the desired delay time is greater than a predetermined time, the SN does not set the UE to not transmit a grant. In this way, the SN can determine whether to set the UE to not transmit a grant by using information on the QoS required for the UE's communication service.

[0240] An SN that receives a request for setting no grant transmission from an MN may notify the MN whether or not the UE in question has been set up for no grant transmission. The SN may notify an acknowledgment (ack) or a rejection (reject) as a response to the request for setting no grant transmission. The SN may notify information for identifying the own node. The SN may notify information for identifying the UE in question. The response to the request for setting no grant transmission may be notified in association with information for identifying the UE.

[0241] When an SN sets a UE to not transmit a grant, it notifies the MN of an ack. The MN can recognize that the SN has set a no-grant transmission for the target UE. The method for notifying the MN or UE of the no-grant transmission setting can be the method described above. The UE can transmit no grant to the SN using the SN's no-grant transmission setting. Also, when an SN notifies the MN of the SN's no-grant transmission setting, the notification can be used as an ack. This can reduce signaling.

[0242] When an SN notifies an MN of a rejection, the notification may include reason information. The reason information may be, for example, grant no transmission not possible, grant no transmission not permitted, overload, lack of resources, etc. This allows the MN to recognize the reason why the SN was unable to set grant no transmission for the target UE. For example, the MN can switch the DC setting to another SN. Alternatively, for example, the MN can perform a process to switch UEs with a long desired delay time among those that have set a DC using the SN to another SN.

[0243] When the SN notifies the MN of Reject, the notification may include a waiting timer. This allows the MN to request the SN to set up grant non-transmission again after the waiting time has elapsed. This allows for flexible processing as a system.

[0244] Figures 16 and 17 show an example of a sequence in which an SN transmits no grant in a split bearer. Figures 16 and 17 are connected at the boundary line BL1617. Figures 16 and 17 show a case in which an MN requests an SN to set no grant transmission. The sequences shown in Figures 16 and 17 include the same steps as the sequences shown in Figures 12 and 13, so the same step numbers are used for the same steps and common explanations will be omitted.

[0245] In steps ST801 to ST809, the UE transmits uplink data to the SgNB in ​​the DC. In step ST1301, the MgNB determines to the UE that no grant is to be transmitted at the SgNB. The MgNB determines a request for setting no grant transmission at the SgNB based on, for example, the UE's QoS information for uplink communication, the load status of the SgNB, and the radio resource usage status at the SgNB.

[0246] For example, the MgNB determines a request for setting the SgNB to not transmit a grant based on the UE's QoS information for uplink communication and the load status of the SgNB. The MgNB may acquire the UE's QoS information for uplink communication and the load status of the SgNB from the UE and the SgNB as appropriate. The UE's QoS information for uplink communication may be acquired, for example, by the method disclosed in FIG. 8. The MgNB may acquire the SgNB's load status from the SgNB. For example, the MgNB requests the SgNB for the load status, and the SgNB notifies the MgNB of its own node's load status. The MgNB can acquire the SgNB's load status by performing this process as appropriate.

[0247] For example, if the desired delay time of the UE's uplink communication is smaller than a predetermined value, the MgNB does not request a no-grant transmission setting while the load situation of the SgNB is higher than the predetermined value, but requests a no-grant transmission setting when the load situation of the SgNB falls below the predetermined value. In this way, the MgNB may decide to request the SgNB to perform a no-grant transmission setting at the SgNB.

[0248] The MgNB that has decided not to transmit a grant at the SgNB to the UE in Step ST1301 requests the SgNB to configure for no grant transmission in Step ST1302. The MgNB may notify the SgNB of information for identifying the target UE and information indicating the configuration request for no grant transmission. In Step ST1303, the SgNB configures the UE for no grant transmission. In Step ST1304, the SgNB notifies the MgNB of a response to the configuration request for no grant transmission. The SgNB may notify the MgNB of information for identifying the target UE and the response to the configuration request for no grant transmission. Figures 16 and 17 show the case of an acknowledgment (ack).

[0249] The SgNB includes configuration information for no grant transmission at the SgNB in ​​the response message (response message to the configuration request for no grant transmission) notified in step ST1304. In this way, the MgNB can obtain the configuration for no grant transmission at the SgNB for the UE. In step ST1104, the MgNB notifies the UE of the configuration information for no grant transmission at the SgNB. In steps ST1105 to ST1108, the UE configures the SgNB for no grant transmission, and when uplink data occurs in the UE, no grant transmission is performed between the UE and the SgNB.

[0250] By doing this, it is possible to achieve lower delay in DC. Also, the MgNB can request the SgNB to set up no grant transmission. The MgNB, which serves as a C-plane node for the UE, can also control the setting for no grant transmission. This makes it possible to avoid complicated control.

[0251] The setting of no grant transmission may be performed for the MN and the SN. The setting of no grant transmission may be performed separately for the MN and the SN.

[0252] Figures 18 and 19 show an example of a sequence in which an MN and an SN transmit no grant in a split bearer. Figures 18 and 19 are connected at the boundary line BL1819. The sequences shown in Figures 18 and 19 include the same steps as the sequences shown in Figures 16 and 17, so the same step numbers are used for the same steps and common explanations will be omitted.

[0253] In step ST1400, DC setting processing is performed between the UE, MgNB, and SgNB. In Fig. 18 and Fig. 19, the UE performs uplink communication with both the MgNB and SgNB. In steps ST1401 to ST1403, the UE performs uplink communication with the MgNB. In steps ST1404 to ST1406, the UE performs uplink communication with the SgNB.

[0254] In Step ST1407, the MgNB determines, for the UE, the configuration of no grant transmission at its own node. As a method of determination, for example, the determination methods disclosed in FIGS. 16 and 17 may be applied by replacing SgNB with MgNB. The MgNB determines a request for configuration of no grant transmission at the MgNB based on, for example, the UE's QoS information for uplink communication, the load situation of the MgNB, and the radio resource usage situation at the MgNB. In Step ST1408, the MgNB notifies the UE of the configuration of no grant transmission at its own node. In Step ST1409, the UE performs configuration of no grant transmission at the MgNB. In Steps ST1410 to ST1412, no grant transmission is performed between the UE and the MgNB.

[0255] In Step ST1301, the MgNB decides to request the UE to set up no grant transmission at the SgNB. As a method of decision, for example, the decision methods disclosed in FIG. 16 and FIG. 17 may be applied. Having decided to transmit no grant at the SgNB to the UE in Step ST1301, the MgNB requests the SgNB to set up no grant transmission in Step ST1302. In Steps ST1106 to ST1108, when uplink data occurs in the UE, no grant transmission is performed between the UE and the SgNB.

[0256] The order of the grant no transmission setting decision in the MgNB and the grant no transmission setting decision in the SgNB may be reversed. A series of processes from each grant no transmission setting decision may be reversed. Furthermore, the grant no transmission setting decision in the MgNB and the grant no transmission setting decision in the SgNB may be performed simultaneously. A series of processes from each grant no transmission setting decision may be performed in parallel.

[0257] By doing this, it becomes possible to transmit no grant between both MgNB and SgNB in ​​DC. By using both nodes, throughput can be improved. Furthermore, by using no grant transmission at both nodes, it is possible to achieve lower delay, so throughput can be further improved.

[0258] Although it has been disclosed that the MN requests the SN to configure the SN to transmit no grant, as another method, the MN may instruct the SN to configure the SN to transmit no grant. Similar to the method of requesting the configuration, the MN may notify the SN of configuration information for transmitting no grant that it requests the SN. The MN may notify the SN of information for identifying its own node. The MN may notify the SN of information for identifying the UE for which the configuration to transmit no grant is to be performed. The instruction to configure the SN to transmit no grant may be notified in association with information for identifying the UE. Xn signaling or X2 signaling may be used to notify the instruction.

[0259] The SN may notify the MN of its load information, the usage status of uplink resources, etc. The SN may also notify information for identifying its own node. For example, the MN uses such information to determine whether to set no grant transmission in the SN for the communication service of the target UE, and if it decides to set no grant transmission, it instructs the SN to set no grant transmission. If the UE has notified the MN of the QoS of the above-mentioned UE communication service, the MN may also use the QoS information to determine whether to set no grant transmission in the SN.

[0260] An SN that receives a setting instruction for no grant transmission from an MN sets the target UE to no grant transmission. If setting information for no grant transmission is notified from the MN, the SN may use the setting received from the MN as the setting for no grant transmission. In this way, the MN can control whether or not to set no grant transmission in the SN for the UE for which DC is to be set.

[0261] A method for requesting a setting change is disclosed. The MN notifies the SN of a request to change the SN's setting of no grant transmission. For example, if the UE's uplink communication does not satisfy the desired QoS, the MgNB determines to request the SgNB to change the setting of no grant transmission with a shorter period. The MN may notify the SN of information about the UE making the setting change request of no grant transmission. The setting change request may be notified in association with information about the UE. The SN may change the setting of no grant transmission for the target UE taking into account the setting change request. The SN notifies the MN of the setting after the change of no grant transmission. The MN notifies the UE of the setting after the change of the SN's setting of no grant transmission.

[0262] The UE changes only the notified settings or setting parameters. This reduces the amount of signaling or information required for notification. The UE can perform no grant transmission to the SN using the newly notified changed settings for no grant transmission from the SN. The SN may notify the UE of the changed settings for no grant transmission. The UE can perform no grant transmission to the SN using the newly notified changed settings for no grant transmission from the SN.

[0263] A method for requesting cancellation of the setting is disclosed. The MN notifies the SN of cancellation of the no grant transmission setting. For example, if the UE's uplink communication satisfies the desired QoS, the MgNB decides to request the SgNB to cancel the no grant transmission setting. The MN may notify information about the UE making the no grant transmission setting cancellation request. The cancellation of the no grant transmission setting may be notified in association with information about the UE making the no grant transmission setting cancellation request. The SN may cancel the no grant transmission setting for the target UE in consideration of the setting cancellation request. The SN notifies the MN of cancellation of the no grant transmission setting. The MN notifies the UE of cancellation of the SN's no grant transmission setting. The SN may also notify the UE of cancellation of the SN's no grant transmission setting. The UE that receives the cancellation notification cancels the no grant transmission setting for the SN.

[0264] The UE may request the MN to configure the MN and / or SN to transmit no grant. The UE may also request the SN to configure the SN and / or MN to transmit no grant. Information indicating a request for the configuration of no grant transmission may be provided and notified. The request for the configuration of no grant transmission may include an identifier of the UE itself. The request for the configuration of no grant transmission may also include an identifier of the node requesting the configuration of no grant transmission and be notified. The node identifier and the request for the configuration of no grant transmission may be associated and notified. RRC signaling may be used for the request. Alternatively, MAC signaling may be used. This makes it possible to notify the request early and with a low error rate. Alternatively, L1 / L2 signaling may be used. This makes it possible to notify the request even earlier.

[0265] When a node receives a request to set no grant transmission from a UE, if the node that sets no grant transmission is different from the node itself, the node requests the node that sets no grant transmission to set no grant transmission. X2 or Xn signaling may be used for notification between nodes.

[0266] For example, when a UE is performing uplink communication with an SN, the UE determines whether the QoS required for the communication (e.g., a desired delay time) is met. For example, it is advisable for the UE to measure the QoS (e.g., a delay time) of the communication. If the required QoS is not met, the UE requests a setting for no grant transmission. In this way, it is possible to request the corresponding node to set no grant transmission according to the communication status at the UE. This makes it possible to flexibly respond to changing communication status and satisfy the required QoS.

[0267] Figures 20 and 21 show an example of a sequence in which an SN performs grant no-transmission in a split bearer. Figures 20 and 21 are connected at the boundary line BL2021. Figures 20 and 21 show a case in which a UE requests a grant no-transmission setting from an MN. The sequences shown in Figures 20 and 21 include the same steps as the sequences shown in Figures 18 and 19, so the same step numbers are used for the same steps and common explanations will be omitted.

[0268] In Step ST1501, the UE determines a request for grant no-transmission configuration at the SgNB. The UE determines the request by using, for example, the UE's uplink communication QoS information, a QoS value in actual communication, etc. In addition, the UE may use support information of the MgNB and the SgNB, for example, supported SCS information, etc.

[0269] When using QoS values ​​in actual communication, the UE may measure the QoS values ​​in actual communication. For example, the UE may measure the delay time, packet loss, bit rate, etc. of uplink packet data in actual communication. The UE compares the desired QoS information with the actually measured QoS value, and if the actually measured QoS value does not satisfy the desired QoS information, determines to request a no-grant transmission setting at the SgNB. The node to request a no-grant transmission setting may be determined using support information of the MgNB and the SgNB. The method by which the UE obtains the support information of the MgNB and the SgNB may be the method disclosed in the first embodiment, i.e., the method by which the MgNB notifies the UE of information for determining the uplink transmission node.

[0270] 20 and 21 show a case where a request for grant no transmission configuration at an SgNB is determined. In Step ST1502, the UE notifies the MgNB of a request for grant no transmission configuration at an SgNB. The UE may notify the MgNB of information identifying the UE itself and information identifying the SgNB. The MgNB can recognize which UE is requested to configure grant no transmission at which SgNB.

[0271] The MgNB that has received the request for setting no grant transmission at the SgNB in ​​Step ST1502 decides to request no grant transmission setting to the SgNB in ​​Step ST1503. In Step ST1302, the MgNB notifies the SgNB of the request for setting no grant transmission. The MgNB that has decided to transmit no grant at the SgNB to the UE in Step ST1503 requests the SgNB to set for no grant transmission in Step ST1302. In Steps ST1106 to ST1108, when uplink data occurs in the UE, no grant transmission is performed between the UE and the SgNB.

[0272] By doing so, it is possible to achieve lower delay in the DC. Also, it is possible to use the situation in the UE, for example, the actually measured QoS value, to determine the request for grant no transmission setting. Therefore, it is possible to set grant no transmission in a timely manner according to the situation in the UE, and it is possible to set a transmission method according to the situation in the UE.

[0273] The CN may request the MN to configure the MN and / or SN to transmit no grant. The CN may also request the SN to configure the SN and / or MN to transmit no grant. Information indicating a request for the configuration of no grant may be provided and notified. Information for identifying the SN and / or MN may also be notified. The request for the configuration of no grant may include an identifier of the UE for which no grant is to be transmitted. Also, the identifier of the node requesting the configuration of no grant may be included in the notification. The node identifier may be associated with the request for the configuration of no grant and notified. Also, information about the PDU session for which no grant is to be transmitted and / or information about the QoS flow may be included in the notification. The request may be made using S1 or NG-C signaling.

[0274] When a node receives a request from a CN to set no grant transmission, if the node that sets no grant transmission is different from the node itself, the node requests the node that sets no grant transmission to set no grant transmission. X2 or Xn signaling may be used for notification between nodes.

[0275] For example, when a UE is performing uplink communication with an SN, the CN determines whether the QoS required for the communication (e.g., a desired delay time) is met. For example, it is advisable for the CN to measure the QoS (e.g., a delay time) of the communication. If the required QoS is not met, the CN requests the setting of no grant transmission. In this way, it is possible to request the corresponding node to set no grant transmission according to the communication status at the UE. This makes it possible to flexibly respond to changing communication status and satisfy the required QoS.

[0276] Figures 22 and 23 show an example of a sequence in which an SN transmits no grant in a split bearer. Figures 22 and 23 are connected at the boundary line BL2223. Figures 22 and 23 show a case in which a CN requests a MN to set no grant transmission. The sequences shown in Figures 22 and 23 include the same steps as the sequences shown in Figures 20 and 21, so the same step numbers are used for the same steps and common explanations will be omitted.

[0277] In step ST1601, the CN determines a request for grant no-transmission configuration at the MgNB and the SgNB. The CN measures, for example, the throughput of the actual uplink communication of the target UE and determines the request using the measurement results. In addition, the CN may use support information of the MgNB and the SgNB, such as information on the supported SCSs.

[0278] For example, if the throughput of uplink communication is lower than a desired value, the CN determines a request for no grant transmission setting at the MgNB and SgNB. The CN may determine which node to request no grant transmission setting from by using support information of the MgNB and SgNB. As a method for the CN to obtain the support information of the MgNB and SgNB, a method may be applied in which the MgNB notifies the CN in advance of information for determining the uplink transmission node. The notification may be made using S1 signaling or NG-C signaling.

[0279] 22 and 23 show a case where a request for grant no transmission configuration of the MgNB and SgNB is determined. In Step ST1602, the CN notifies the MgNB of a request for grant no transmission configuration of the MgNB and SgNB. The CN may notify the MgNB of information identifying the target UE and information identifying the SgNB. The MgNB can recognize which UE is requested to be configured with grant no transmission at which SgNB.

[0280] In step ST1602, the CN may notify some or all of the grant no transmission configuration information of the MgNB and the SgNB. For example, the CN sets the period and offset of the grant no transmission resources to be the same for both the MgNB and the SgNB and notifies the configuration. In this way, the grant no transmission timing of the MgNB and the SgNB becomes the same, making it possible to suppress an increase in the amount of delay due to the timing difference.

[0281] The MgNB that has received the request for setting no grant transmission at the MgNB and SgNB in ​​Step ST1602 performs the setting no grant transmission at the MgNB. Furthermore, in Step ST1603, the MgNB decides to request the SgNB to set no grant transmission. In Step ST1302, the MgNB notifies the SgNB of the request for setting no grant transmission.

[0282] In Step ST1304, the MgNB receives information identifying the target UE and information indicating ack from the SgNB. The MgNB also receives grant no transmission setting information at the SgNB. In Step ST1604, the MgNB notifies the UE of the grant no transmission setting information of its own node and the grant no transmission setting information of the SgNB.

[0283] In Step ST1605, the MgNB, having confirmed that the notification in Step ST1604 was successful, notifies the CN of the completion of the grant no transmission configuration. The completion notification may include information for identifying the target UE and information for identifying the node in which the grant no transmission configuration has been performed. This allows the CN to recognize that the grant no transmission configuration has been performed by the MgNB and SgNB.

[0284] The UE that has received the configuration for no grant transmission from the MgNB and SgNB in ​​Step ST1604 configures the MgNB and SgNB for no grant transmission in Step ST1606. When uplink data occurs in the UE, no grant transmission is performed between the UE and MgNB in ​​Steps ST1607 to ST1609, and no grant transmission is performed between the UE and SgNB in ​​Steps ST1610 to ST1612.

[0285] In this way, it is possible to achieve lower delays in the DC. In addition, the CN sets the grant no-transmission setting request of each node and some or all of the grant no-transmission settings, thereby reducing the delay time of upstream communication as a system.

[0286] The CN may notify the MN or SN of the grant no transmission setting at each node. The CN may notify the node that has been requested to send the grant no transmission setting of the grant no transmission setting together with the grant no transmission setting request sent from the CN to the MN or SN, or by including the grant no transmission setting in the request. If the node that has received the grant no transmission setting request from the CN is different from the node itself, the node that has received the grant no transmission setting request may notify the node that will send the grant no transmission setting of the grant no transmission setting.

[0287] The CN may notify some or all of the grant no-transmission settings. Also, when notifying multiple nodes of the grant no-transmission settings, the CN may set some or all of the grant no-transmission settings to the same for the multiple nodes and notify them of the settings. A node that has been notified of the grant no-transmission setting from the CN performs its own grant no-transmission setting taking the settings into consideration.

[0288] For example, the CN requests the MN and SN to set no grant transmission. At this time, the MN and SN are set to the same period for no grant transmission. By doing so, it is possible to make the delay time of uplink data transmission approximately the same for the MN and SN. The CN can perform unified control over the nodes of the RANs under its umbrella.

[0289] The MN or SN may notify the UE or CN of a response to the grant no transmission setting request notified by the UE or CN to the MN or SN. The response may be notified including an identifier of the node for which the grant no transmission setting is requested. The node for which the grant no transmission setting is requested and the response to the grant no transmission setting request at the node may be notified in association with each other.

[0290] In response to the request for grant no transmission setting, the MN or SN may notify the target UE whether or not the setting for grant no transmission has been performed. The MN or SN may notify an acknowledgment (ack) or a rejection (reject). The MN or SN may notify information for identifying the target UE. The response to the request for grant no transmission setting may be notified in association with information for identifying the UE.

[0291] The above-mentioned method may be applied to the response to the grant no transmission setting request between the MN and the SN. The node that receives the response to the grant no transmission setting request may notify the UE or CN of the response to the grant no transmission setting request in response to the response. Similar effects can be obtained.

[0292] The method disclosed in Variant 1 of the First Embodiment is applicable to bearer types that use SCG. That is, the method disclosed in Variant 1 of the First Embodiment can be applied not only to MCG split bearers and SCG split bearers but also to SCG bearers. It is possible to enable grant-less transmission in SNs in SCG bearers. Furthermore, the method disclosed in Variant 1 of the First Embodiment can also be applied to MC (multi connectivity) as appropriate. It is sufficient to use two or more SNs. When a UE is connected to one MN and two or more SNs, grant-less transmission may be configured in one or two or more SNs within the range of the number of connected SNs.

[0293] By using the method disclosed in the first modification of the first embodiment, it is possible to enable the SN to transmit no grant when DC or MC is set. By enabling the SN to transmit no grant, it is possible to eliminate the need for the SN to receive an SR and the subsequent uplink grant transmission, and it is possible to reduce the delay time of the uplink data transmission in the SN.

[0294] No grant transmission is also performed in CA (Carrier Aggregation). No grant transmission can be configured in CA. In other words, no grant transmission is supported in CA. No grant transmission may be supported in one or more CCs (cells) of CA.

[0295] In CA, SR is transmitted in a predetermined cell. For example, SR is transmitted in PCell, PUCCSH SCell, and SPCell. The cell configured for no grant transmission does not have to be a cell capable of transmitting SR. The no grant transmission configuration may be configured for a cell transmitting uplink data. Since the configuration is not limited to cells capable of transmitting SR, for example, no grant transmission can be configured for a UE in a cell with a good radio environment. The UE can transmit no grant in a cell with a good radio environment, and can achieve low latency and high throughput in uplink communication.

[0296] The MN notifies the UE of the grant no-transmission setting for one or more cells. The MN may notify each node (MN and SN) of the grant no-transmission setting for each cell. The MN may notify information for identifying the cell and grant no-transmission setting information. The MN may acquire the grant no-transmission setting for each SN in advance. The acquisition method may be the method disclosed in the grant no-transmission setting method in the DC mentioned above.

[0297] Each node may notify the UE of the grant no-transmission setting for one or more cells. The MN may notify the grant no-transmission setting for each cell of the own node. The SN may notify the grant no-transmission setting for each cell of the own node.

[0298] The RRC setting of each cell for no grant transmission may be notified from the MN or each node to the UE by RRC signaling. The L1 setting of each cell for no grant transmission may be notified from each cell to the UE by L1 signaling. The L1 setting may be notified by including it in DCI.

[0299] A cell may notify the UE of the L1 setting of one or more other cells without grant transmission. It is recommended to include information for identifying the cell that will be set to no grant transmission and the L1 setting of no grant transmission in the DCI. In this way, the UE only needs to receive the control channel of a specific cell, and does not need to receive the control channels of all cells at all times. This reduces the power consumption of the UE.

[0300] In the case of CA, scheduling of cells performing CA is performed by MAC of each node. Therefore, even if a cell notifies the L1 setting of another cell, the setting of radio resources for no grant transmission of the other cell and the activation / deactivation of no grant transmission can be reflected in a timely manner. This makes it possible to improve the utilization efficiency of radio resources.

[0301] The UE may determine which cell among the cells configured to not transmit grants will be used to transmit data. If L1 configuration is performed, the UE may select a cell to transmit data from among the activated cells. For example, the UE may measure the downlink path loss of each cell and determine to transmit uplink data from the cell with the smallest path loss.

[0302] The node may determine which cell among the cells configured to not transmit grants will transmit data from. Each node may also determine which cell will transmit data from. Only the determined cell notifies the UE of act in the L1 configuration. The determined cell notifies other cells of deact in the L1 configuration. In this manner, the node can determine which cell the UE will transmit uplink data from. For example, the node may receive an uplink sounding signal from the UE to each cell, measure the uplink communication quality of each cell, and determine to transmit uplink data from the cell with the best uplink communication quality.

[0303] Information for specifying a cell for uplink data transmission may be provided. The node may include the information in the RRC configuration and notify it by RRC signaling. Alternatively, the node may include the information in the MAC CE and notify it by MAC signaling. It becomes possible to dynamically configure no grant transmission. Furthermore, since HARQ is applied, it becomes possible to reduce reception errors. Alternatively, information for specifying a cell for uplink data transmission may be included in the L1 configuration and notified by L1 signaling. It becomes possible to dynamically configure no grant transmission. It becomes possible to immediately configure no grant transmission for UEs for which HARQ is not performed.

[0304] Some or all of the grant no-transmission configuration may be the same across multiple cells. The same grant no-transmission configuration may be a common configuration across all cells. For example, the timing of grant no-transmission resources may be made different across multiple cells. This allows uplink data communication to be started by a cell that can use grant no-transmission resources as quickly as possible after uplink data is generated in the UE. This further reduces the delay time in uplink communication.

[0305] This allows grant-free transmission in one or more cells even in CA. For example, a UE can start data communication in a cell with a good radio wave propagation environment. Furthermore, it can start uplink communication not only in cells where SR transmission is possible but also in other cells.

[0306] Embodiment 2 In the upstream communication of communication services that require low latency, low latency characteristics can be obtained by setting no grant transmission. However, for communication services that require not only low latency characteristics but also high reliability characteristics, such as URLLC services, the requirements cannot be met by simply setting no grant transmission.

[0307] Solutions to the aforementioned problems are disclosed below.

[0308] In packet duplication, in which the same packet is duplicated and transmitted using a DC, it is possible to set no grant transmission. During packet duplication setup, it is possible to set no grant transmission in the MN. During packet duplication setup, it is possible to set no grant transmission in the SN as well. Alternatively, during packet duplication setup, it is possible to set no grant transmission in either the MN or the SN. During packet duplication setup may include during packet duplication setup processing.

[0309] Packet duplication may be set for uplink communication for which no grant transmission is set. When packet duplication is performed for uplink communication for which no grant transmission is set, no grant transmission setting is also possible in the SN. By setting both packet duplication and no grant transmission in this way, reliability can be improved in addition to low latency characteristics.

[0310] In packet duplication using DC, packet duplication is configured between the MN and the UE, and the SN does not need to recognize the packet duplication configuration. The SN only needs to perform the same processing as normal packet data transmission and reception. On the other hand, as mentioned above, RRC configuration is required to configure no grant transmission. Therefore, when attempting to configure no grant transmission using packet duplication using DC, the SN cannot recognize whether or not the no grant transmission configuration is necessary, which causes a problem in that the SN cannot configure no grant transmission.

[0311] Solutions to the aforementioned problems are disclosed below.

[0312] The MN requests the SN to set no grant transmission. During packet duplication setting, the MN requests the SN to set no grant transmission. The SN notifies the MN of the no grant transmission setting. The MN notifies the UE of the no grant transmission setting set in the own node and the no grant transmission setting of the SN. The method for the no grant transmission setting request from the MN to the SN and the no grant transmission setting between the MN, SN, and UE may be the method disclosed in Variant 1 of Embodiment 1, as appropriate.

[0313] For example, instead of the MN requesting the SN to set up no grant transmission, a method may be applied in which the MN instructs the SN to set up no grant transmission.

[0314] By doing this, the SN can recognize whether or not the setting of no grant transmission is necessary, and can set the no grant transmission in the SN. Therefore, the no grant transmission setting can be set by packet duplication using the DC. Low latency and high reliability characteristics can be obtained.

[0315] The MN may request the SN to synchronize the timing of the resources for no grant transmission. The timing of the resources for no grant transmission may be the period and offset of the resources for no grant transmission. The MN may notify the SN of these parameters among the grant no transmission setting parameters of the own node. The SN will be able to set these parameters.

[0316] In this way, the transmission timing from the UE to both nodes can be aligned, which makes it possible to reduce the increase in delay time caused by different transmission timings to each node.

[0317] The MN may request the SN to change the timing of the grant no-transmission resource. The MN may set the timing-related parameters of the grant no-transmission setting parameters of the own node to different values ​​and notify the SN of the setting values. The SN becomes able to set the parameters.

[0318] If the transmission timing to each node is the same, the UE's transmission power must be distributed to each node, which may result in a decrease in transmission power to the nodes.By varying the transmission timing to each node, it is possible to suppress a decrease in uplink transmission power from the UE to each node.

[0319] The MN may request the SN to vary the timing of resources for no-grant transmission within a predetermined range. The MN may set parameters related to timing among its own node's no-grant transmission setting parameters to different values ​​within a predetermined range and notify the SN of the set values. The SN becomes able to set the parameters.

[0320] By doing so, it is possible to suppress a decrease in uplink transmission power to each node, and by keeping the transmission timing to each node within a predetermined range, it is possible to reduce delay time.

[0321] Even when an attempt is made to set packet duplication for uplink communication for which no grant transmission is set in the MN, the SN cannot recognize whether or not the no grant transmission setting is necessary, resulting in the problem that the SN cannot set no grant transmission.

[0322] Solutions to the aforementioned problems are disclosed below.

[0323] The MN notifies the UE that packet duplication using DC is to be set for uplink communication for which no grant transmission is set. The MN also requests the SN to set no grant transmission. The MN may notify the SN of an instruction to set no grant transmission. The SN notifies the MN of the no grant transmission setting. The MN notifies the UE of the no grant transmission setting set in the own node and the no grant transmission setting of the SN. The method for setting no grant transmission between the MN, SN, and UE, such as a request from the MN to the SN to set no grant transmission, may be the method disclosed in Variant 1 of Embodiment 1, as appropriate.

[0324] By doing this, the SN can recognize whether or not the setting of no grant transmission is necessary, and can set the no grant transmission in the SN. Therefore, it becomes possible to set packet duplication for uplink communication in which no grant transmission is set in the MN. Low delay characteristics and high reliability characteristics can be obtained.

[0325] 24 to 26 show an example of a sequence for setting up no grant transmission in packet duplication. FIGS. 24 to 26 are connected at the positions of boundary lines BL2425 and BL2526. In Step ST1701, the MgNB decides to perform uplink packet duplication using a split bearer for the UE. In Step ST1702, the MgNB performs processing for setting up a DC using a split bearer between the UE and the SgNB. In Step ST1703, the MgNB notifies the UE of the setting up of uplink packet duplication. RRC signaling may be used for this notification. In Step ST1704, the MgNB notifies the UE of the act of packet duplication. MAC signaling may be used for this notification.

[0326] The UE that has received the packet duplication act in Step ST1704 starts packet duplication in Step ST1705. The UE that has started packet duplication duplicates uplink data and transmits the uplink data to the MgNB and SgNB. In Steps ST1706 to ST1708, the UE transmits the uplink data to the MgNB, and in Steps ST1709 to ST1711, the UE transmits the uplink data to the SgNB.

[0327] In Step ST1712, the SgNB transmits the uplink data received from the UE to the MgNB. The S1 interface or the Xn interface may be used for transmitting the uplink data. In Step ST1713, the MgNB compares the uplink data received by the MgNB with the uplink data received from the SgNB and deletes duplicated uplink data. In this way, uplink packet duplication is performed using the split bearer between the MgNB and the SgNB.

[0328] In Step ST1714, the MgNB determines the grant no transmission configuration for the MgNB and the SgNB. The determination methods disclosed in FIG. 16 and FIG. 17 may be applied to this determination method. When setting no grant transmission for uplink data in which packet duplication is performed, the grant no transmission configuration for both the MgNB and the SgNB may be determined. In Step ST1715, the MgNB notifies the SgNB of an instruction to set up for no grant transmission. The MgNB may notify the SgNB of information identifying the target UE. The MgNB may notify the SgNB of some or all of the grant no transmission configuration.

[0329] The MgNB may notify the SgNB of the period and offset of the grant transmission resource as configuration information for no grant transmission. By matching the period and offset of the grant transmission resource between the SgNB and the MgNB, it is possible to suppress an increase in the amount of delay caused by different timing of the grant transmission resource between the SgNB and the MgNB.

[0330] The SgNB that has received the instruction to configure for no grant transmission from the MgNB performs the configuration for no grant transmission in Step ST1716. The configuration for no grant transmission involves the retention of radio resources, but when the SgNB receives the instruction from the MgNB, it may perform the configuration for no grant transmission for the target UE, prioritizing it over other UEs. In Step ST1717, the SgNB notifies the UE of a response to the instruction to configure for no grant transmission from the MgNB. Here, the SgNB notifies an ack. The SgNB notifies the UE of information identifying the target UE and the configuration for no grant transmission at the SgNB. In Step ST1718, the MgNB notifies the UE of its own node's configuration for no grant transmission and the SgNB's configuration for no grant transmission.

[0331] In Step ST1719, the UE configures the MgNB and SgNB for no grant transmission. In Steps ST1720 to ST1722, the UE transmits no grant to the MgNB. Also, in Steps ST1723 to ST1725, the UE transmits no grant to the SgNB. In Step ST1726, the SgNB transmits the uplink data received from the UE to the MgNB. In Step ST1727, the MgNB deletes duplicated uplink data.

[0332] In the above example, the MgNB notified the SgNB of an instruction to set up for no grant transmission, but the MgNB may also notify the SgNB of a request for setting up for no grant transmission. Also, the SgNB notified the MgNB of an ack, but the SgNB may also notify the MgNB of an ack. For example, when the SgNB receives a request for setting up for no grant transmission and is unable to set up for no grant transmission due to a lack of resources in the own node, it notifies the MgNB of Reject. The lack of resources may also be notified as reason information.

[0333] The MgNB that receives the Reject notification may, for example, decide to configure only the node itself to not transmit a grant, and notify the UE of the configuration for not transmitting a grant only from the MgNB.

[0334] The MgNB may again determine a request for no grant transmission setting to the SgNB and notify the SgNB of the request for no grant transmission setting. If the resource shortage has been resolved, the SgNB notifies the MgNB by including the no grant transmission setting at the SgNB in ​​the Ack. The MgNB may notify the UE of the no grant transmission settings of the MgNB and the SgNB. If there is no change in the no grant transmission setting of the MgNB, only the no grant transmission setting of the SgNB may be notified.

[0335] By doing so, it is possible to transmit no grant in uplink packet duplication using split bearers between the MgNB and the SgNB. Therefore, it is possible to achieve lower delays even during packet duplication. It is possible to obtain high reliability and low delay characteristics.

[0336] Uplink packet duplication setting may be performed in the DC setting process. For example, the uplink packet duplication setting information may be included in an RRC connection reconfiguration message notified from the MN to the UE, thereby notifying the information. The UE that receives the RRC connection reconfiguration message in the DC setting process performs uplink packet duplication setting together with DC setting. In this way, the amount of RRC signaling can be reduced.

[0337] Figures 27 to 29 show an example of a sequence for setting packet duplication for uplink communication for which no grant transmission is set. Figures 27 to 29 are connected at boundary lines BL2728 and BL2829. The sequence shown in Figures 27 to 29 includes the same steps as the sequence shown in Figures 24 to 26, so the same step numbers are used for the same steps and common explanations will be omitted.

[0338] In Step ST1801, the MgNB notifies the UE of a grant no transmission setting of the MgNB. In Step ST1802, the UE performs a grant no transmission setting for the MgNB. In Steps ST1803 to ST1805, when uplink data occurs in the UE, grant no transmission is performed between the UE and the MgNB.

[0339] In Step ST1806, the MgNB decides to perform packet duplication using a split bearer. In Step ST1714, the MgNB decides to configure no grant transmission between the MgNB and SgNB. In Step ST1807, the MgNB that has decided to perform packet duplication using a split bearer performs DC configuration processing between the UE and SgNB. After the DC configuration processing is performed in Step ST1807, in Step ST1715, the MgNB notifies the SgNB of an instruction to configure no grant transmission by the SgNB.

[0340] In Steps ST1716 to ST1719, the MgNB and SgNB configure the UE to transmit no grant. The MgNB may change the configuration for no grant transmission, and in Step ST1718 notify the UE of the changed configuration for no grant transmission. The MgNB, which has notified the UE of the configuration for no grant transmission of the MgNB and SgNB in ​​Step ST1718, notifies the UE of the configuration for uplink packet duplication in Step ST1808. RRC signaling may be used for this notification. In Step ST1809, the MgNB notifies the UE of the act of packet duplication. MAC signaling may be used for this notification.

[0341] The UE, which has received the packet duplication act from the MgNB in ​​Step ST1809, starts duplicating uplink data in Step ST1810. When uplink data occurs in the UE, uplink data packet duplication is performed, and no grant is transmitted between the UE and MgNB in ​​Steps ST1720 to ST1722, and no grant is transmitted between the UE and SgNB in ​​Steps ST1723 to ST1725.

[0342] In this way, packet duplication can be set for uplink communication for which no grant transmission is set. Therefore, by performing packet duplication for uplink communication that has achieved low latency characteristics by no grant transmission, it is possible to obtain higher reliability. It is possible to obtain both low latency characteristics and high reliability.

[0343] A setting for no grant transmission may be performed in the DC setting process. For example, a setting request for no grant transmission or a setting instruction for no grant transmission may be included in an Xn / X2 message notified from an MN to an SN, such as an SgNB modification request message (SgNB modification request). Also, for example, a setting information for no grant transmission may be included in an Xn / X2 message notified from an SN to an MN, such as an SgNB modification request acknowledge message (SgNB modification request Acknowledge). This method may be applied to the method disclosed in the first modification of the first embodiment. In this way, the amount of Xn / X2 signaling can be reduced.

[0344] Also, for example, the information may be notified by including the configuration information for no grant transmission in an RRC connection reconfiguration message notified from the MN to the UE. The UE that receives the RRC connection reconfiguration message in the DC configuration process performs the configuration for no grant transmission together with the DC configuration. This method may be applied to the method disclosed in the first modification of the first embodiment. In this way, the amount of RRC signaling can be reduced.

[0345] Uplink packet duplication setting may be performed in the DC setting process. For example, the uplink packet duplication setting information may be included in an RRC connection reconfiguration message notified from the MN to the UE, thereby notifying the information. The UE that receives the RRC connection reconfiguration message in the DC setting process performs uplink packet duplication setting together with DC setting. In this way, the amount of RRC signaling can be reduced.

[0346] Uplink packet duplication setting may be performed in the process of setting up for no grant transmission. For example, uplink packet duplication setting information may be included in the RRC signaling for setting up for no grant transmission notified from the MN to the UE, thereby notifying the UE of this information. A UE that receives the RR signaling for setting up for no grant transmission performs uplink packet duplication setting together with the setting up for no grant transmission. In this way, the amount of RRC signaling can be reduced.

[0347] In the grant no transmission setting, the act / deact of the grant no transmission setting may be performed using MAC signaling. Information on the grant no transmission setting act / deact may be provided for each node. This information may be included in the MAC CE. The MN may notify the UE of the act / deact of the grant no transmission setting by the MAC CE. The SN may also notify the UE of the act / deact of the grant no transmission setting by the MAC CE.

[0348] The UE that receives the act / deact information of the grant no-transmission setting of each node performs the grant no-transmission setting for each node. By providing the grant no-transmission setting act / deact information of each node in the MAC signaling, the grant no-transmission setting for the UE can be dynamically and timely performed. This makes it possible to reduce the wasteful use of radio resources.

[0349] The packet duplication act / deact setting is performed by MAC signaling. The MAC signaling including the MAC CE for the packet duplication act / deact setting may include the MAC CE for act / deact information of each node's grant no-transmission setting, thereby notifying the information. By notifying the information in the same MAC signaling, the amount of signaling can be reduced.

[0350] Figures 30 and 31 show an example of a sequence in which packet duplication act and grant no transmission setting act are notified by the same signaling, and packet duplication and grant no transmission setting are performed. Figures 30 and 31 are connected at the position of boundary line BL3031. The sequences shown in Figures 30 and 31 include the same steps as the sequences shown in Figures 27 to 29, so the same step numbers are used for the same steps and common explanations will be omitted.

[0351] In Step ST1901, the MgNB decides to perform packet duplication using a split bearer for the UE, and at that time decides to configure no grant transmission between the MgNB and SgNB. In Step ST1902, the MgNB performs DC configuration processing between the UE and SgNB. After the DC configuration processing is performed in Step ST1902, in Step ST1715, the MgNB notifies the SgNB of an instruction to configure no grant transmission for the SgNB.

[0352] In steps ST1716 to ST1718, the MgNB and SgNB are configured to transmit no grant to the UE. The MgNB, which has notified the UE of the configuration for no grant transmission between the MgNB and SgNB in ​​step ST1718, notifies the UE of the configuration for uplink packet duplication in step ST1808. In step ST1903, the MgNB notifies the UE of the act of packet duplication and the act of the configuration for no grant transmission between the MgNB and SgNB by the same signaling. MAC signaling may be used for this notification.

[0353] For example, a MAC CE including an act for packet duplication and a MAC CE including an act for configuring the MgNB and SgNB for no grant transmission are notified in the same MAC PDU. The UE that has received the act for packet duplication and the act for configuring the MgNB and SgNB for no grant transmission in Step ST1903 configures the MgNB and SgNB for no grant transmission in Step ST1904 and starts packet duplication.

[0354] When uplink data occurs in the UE, packet duplication of the uplink data is performed, and in steps ST1720 to ST1722, no grant is transmitted between the UE and MgNB, and in steps ST1723 to ST1725, no grant is transmitted between the UE and SgNB.

[0355] In this way, it is possible to obtain low latency characteristics and high reliability. Also, by having the MAC CE act / deact the grant no transmission setting, when the MgNB wants to start or stop grant no transmission to the UE, it is possible to dynamically control. This makes it possible to improve the efficiency of radio resource usage. Also, by notifying the act / deact of packet duplication and the act / deact of grant no transmission setting by the same MAC signaling, it is possible to reduce the amount of signaling.

[0356] In packet duplication, in which the same packet is duplicated and transmitted using CA, it is possible to set no grant transmission. During packet duplication setup, it is possible to set no grant transmission in a cell in which packet duplication is performed. During packet duplication setup may include during packet duplication setup processing.

[0357] Packet duplication (CA) may be set for uplink communication for which no grant transmission is set. When packet duplication is performed for uplink communication for which no grant transmission is set, no grant transmission setting is also possible in the cell where packet duplication is performed.

[0358] The node notifies the UE of the grant no-transmission setting set in the cell where packet duplication is performed. This notification method may be appropriately applied to the method disclosed in the method for enabling grant no-transmission setting in packet duplication using DC described above.

[0359] By doing this, it becomes possible to set no grant transmission in packet duplication (CA). Packet duplication (CA) can be set for uplink communication where no grant transmission is set. This makes it possible to obtain low latency characteristics and high reliability. It also makes it possible to obtain low latency characteristics and high reliability using a single node.

[0360] Embodiment 3 In uplink preemption transmission (see Non-Patent Document 14 (R1-1712747)), a UE performing preemption transmission transmits an SR to a gNB. The UE performing preemption transmission may be, for example, a UE performing URLLC communication. The gNB notifies the UE to be preempted of information indicating that preemption communication will occur. The notification information may include information on frequency resources used for preemption transmission. The notification information may include information on time resources. The notification information may include information on power resources. The UE to be preempted may be, for example, a UE performing eMBB communication.

[0361] The gNB may configure all or some of its subordinate UEs to receive information indicating that preemption communication will occur. The UEs may use the configuration to start receiving information indicating that preemption communication will occur. The UE to be preempted may be the UE for which the configuration has been configured. The same may apply hereinafter.

[0362] The preempted UE may use the notification to reduce uplink transmission power in the frequency and / or time resource where the preemption transmission is performed, or may stop uplink transmission power in the resource, thereby improving the reliability of preemption communication.

[0363] The preempted UE may not transmit uplink data that was scheduled to be transmitted in the frequency and / or time resource where the preemption transmission is performed. This allows for a reduction in the amount of processing in the UE and the gNB. As another example, the UE may transmit the uplink data using resources other than the resource. For example, the UE may transmit the uplink data after the time resource where the preemption transmission is performed. The UE may also terminate transmission of uplink data that cannot be transmitted within the scheduling grant instructed by the gNB. Whether not to transmit the uplink data and / or to transmit the uplink data using resources other than the resource may be determined using the decoding characteristics of the gNB. Improving HARQ decoding characteristics in uplink transmission allows for improved reliability in uplink communication for the preempted UE.

[0364] As another example, the preempted UE may redo the encoding and modulation processes. The aforementioned redo may be applied, for example, to uplink data transmitted in time resources after the preemption transmission. The aforementioned redo may involve, for example, increasing the coding rate. A method for redoing the encoding and modulation processes due to preemption transmission (e.g., coding rate, pre-encoded data to be re-encoded, etc.) may be defined in advance by a standard, or the preempted UE may notify the base station of information regarding the method. For example, the notification may be performed using uplink L1 / L2 signaling or MAC signaling. This may prevent, for example, loss of uplink data transmission from the preempted UE due to the preemption transmission.

[0365] The gNB notifies the UE that performs preemption transmission (hereinafter, sometimes referred to as a preemption UE) of an uplink grant. The UE that performs preemption transmission uses the grant to perform uplink preemption transmission.

[0366] When the above-mentioned method is applied, the following problem occurs. That is, a UE that performs preemption transmission needs to transmit an SR to a gNB after data to be transmitted on the uplink is generated, so it takes time before the preemption transmission is actually performed. This causes a problem that low latency cannot be ensured in uplink preemption transmission.

[0367] As a solution to the above problem, a UE performing preemption transmission may notify a preempted UE (hereinafter, sometimes referred to as a preempted UE) of information indicating that preemption communication will be performed. The notified information may include information on frequency resources used for preemption transmission. The notified information may include information on time resources. The notified information may include information on power resources. The preempted UE may not transmit uplink data that was scheduled to be transmitted in the frequency and / or time resources in which preemption transmission is performed. This allows the UE performing preemption transmission to perform the preemption transmission quickly.

[0368] When the above-described method is applied, the following problems occur. That is, when the UE performing the preemption transmission and the UE being preempted are far apart, the UE being preempted may not correctly receive the notification of the information. As a result, the UE being preempted transmits uplink data at the timing of the preemption transmission, causing interference with the preemption transmission. Furthermore, the gNB may not be able to grasp the timing of the preemption transmission and may not correctly receive the preemption transmission signal. This causes a problem of reduced reliability of preemption communication.

[0369] Solutions to the aforementioned problems are disclosed below.

[0370] The gNB sends a preemption indication to the UE to be preempted. The indication may indicate a timing at which a preemption transmission may occur. That is, the preemption transmission may or may not actually occur at the timing. The timing indicated by one indication may be one timing or multiple timings.

[0371] The frequency resource used for transmitting the preemption instruction from the gNB may be a region different from the region used for receiving downlink user data of the preempted UE. For example, a frequency resource for the preemption instruction may be provided. This allows, for example, the preempted UE to easily understand the occurrence of preemption.

[0372] The gNB may broadcast information about frequency resources used to transmit a preemption command to UEs under its control. The UEs under the control of the gNB in ​​the above-mentioned example may include UEs to be preempted. As another example, the gNB may individually notify UEs under its control of information about the frequency resources. RRC individual signaling may be used for the individual notification. For example, information about the frequency resources may be included in signaling of an RRC connection reconfiguration from the gNB to the UEs under its control.

[0373] As another example of the frequency resource, the same region as that used for receiving downlink user data of the UE to be preempted may be used. For example, a PDCCH may be used. The gNB may include information on multiple timings at which preemption communication may occur in the PDCCH. This makes it possible to save frequency resources in the communication system. The above-mentioned PDCCH may be a PDCCH individual to a UE. This makes it possible to flexibly control resources for each UE. A PDCCH common to multiple UEs, for example, a PDCCH common to a group (Group common PDCCH), may be used. This makes it possible to reduce the amount of signaling required for a preemption instruction.

[0374] The gNB may encode and / or modulate the preemption indication using information about the UE to be preempted. For example, the gNB may encode and / or modulate the preemption indication using the C-RNTI of the UE to be preempted. The UE to be preempted may obtain the preemption indication using the information. This may, for example, prevent other UEs from erroneously obtaining the preemption indication, thereby preventing a decrease in efficiency of the communication system.

[0375] As an example of the encoding and / or modulation of the preemption indication described above, scrambling of a CRC code, for example, scrambling using the CRC code and all or part of the C-RNTI, may be used. The scrambling described above may be, for example, an exclusive OR operation between each bit of the CRC code and the C-RNTI. As another example, scrambling using the information bits of the preemption indication and all or part of the C-RNTI may be used. As another example, a CRC code may be derived using a bit string obtained by bit-combining the information bits of the preemption indication and all or part of the C-RNTI. This bit string may be used for other encoding processes.

[0376] As another example, information about the UE to be preempted may be used for modulation. For example, information about the sequence of a DMRS associated with a preemption instruction may be determined using information about the UE to be preempted. The information about the sequence may be, for example, a root index in a ZC (Zadoff-Chu) code, a cyclic shift amount (hereinafter sometimes referred to as CS), or a combination of both. For example, the root index and the cyclic shift amount in the ZC code may be determined using a C-RNTI. Another example of the information about the sequence may be a scrambling identifier. This may, for example, reduce the amount of processing in UEs other than the UE to be preempted.

[0377] As another example, the constellation value of each RE after modulating the preemption information may be changed using information about the UE to be preempted. For example, a predetermined number of bits from the beginning of the C-RNTI may be extracted and converted into a constellation value, and an operation may be performed between the obtained constellation value and the constellation value of the first RE after modulating the preemption information, and the result may be used for transmission. A predetermined number of bits next to the extracted bits of the C-RNTI may be extracted and converted into a constellation value, and an operation may be performed between the obtained constellation value and the constellation value of the second RE after modulating the preemption information. Similarly, an operation may be performed between the constellation value of each RE after modulating the preemption information and the C-RNTI. The above operation may be, for example, a complex multiplication. In the above complex multiplication, the constellation value of each RE after modulating the preemption information and / or the constellation value converted from the C-RNTI may be a complex conjugate. The above operation may, for example, reduce the amount of calculation in the modulation process.

[0378] The following (1) to (6) are disclosed as information contained in the preemption instruction transmitted from the gNB to the UE to be preempted.

[0379] (1) Frequency resources used for preemption transmission.

[0380] (2) Time resources used for preemption transmission.

[0381] (3) Whether or not the UE to be preempted is transmitting uplink.

[0382] (4) The uplink transmit power of the UE to be preempted.

[0383] (5) Information about frequency and time resources used for transmitting uplink data that overlaps with preemption transmission. As this information, three specific examples (5-1) to (5-3) are shown below.

[0384] (5-1) Do not send.

[0385] (5-2) Transmitted in conjunction with a preemption transmission.

[0386] (5-3) Transmitting outside the frequency and time resources for preemption transmission.

[0387] (6) A combination of (1) to (5) above.

[0388] The above (1) may be, for example, in units of RB, which allows, for example, a UE to be preempted to transmit uplink data using frequency resources other than the frequency resources used for preemption transmission.

[0389] The above (2) may be, for example, a symbol unit. The symbol unit may be a symbol unit for the UE to be preempted. This allows, for example, the UE to be preempted to transmit uplink data using symbols other than those used for preemption transmission.

[0390] Regarding the above (3), for example, uplink transmission of the preempted UE may not be performed. This makes it possible to reduce interference with the preemption communication. This makes it possible to improve the reliability of the preemption communication. As another example, uplink transmission of the preempted UE may be performed. This makes it easier to control uplink transmission in the preempted UE.

[0391] The above (4) may be, for example, the value of uplink transmission power itself or a value indicating the difference in uplink transmission power. This makes it possible to ensure the reliability of preemption transmission by, for example, reducing the uplink transmission power of the UE to be preempted at the preemption transmission timing.

[0392] In the above (5-1), the preempted UE may not transmit uplink data that overlaps with the preemption transmission. For example, the UE may mask the uplink data that overlaps with the preemption transmission. This simplifies processing in the gNB and the UE and ensures the reliability of the preemption transmission.

[0393] In the above (5-2), the preempted UE may transmit uplink data that overlaps with the preemption transmission using the frequency and time resources of the preemption transmission, which further simplifies the processing in the gNB and the UE.

[0394] In the above (5-3), the preempted UE may rearrange the uplink data that overlaps with the preemption transmission to frequency and time resources different from the frequency and time resources used in the preemption transmission, and transmit the uplink data. Information regarding the frequency and time resources used for the rearrangement may be included in the above (5-3). The time resources used in the preemption transmission may be frequency resources different from the frequency resources used in the preemption transmission. Alternatively, frequency and time resources after the time resources used in the preemption transmission may be used. This, for example, can ensure the continuity of uplink transmission data for the preempted UE, thereby improving the HARQ decoding performance in the gNB.

[0395] As another example of the above (5-3), the preempted UE may redo the encoding and modulation processes. The redo may be applied, for example, to uplink data transmitted in time resources after the preemption transmission. The redo may involve, for example, increasing the coding rate. A method for redoing the encoding and modulation processes due to preemption transmission (e.g., coding rate, pre-encoded data to be re-encoded, etc.) may be defined in advance by a standard, or the preempted UE may notify the base station of information regarding the method. For example, uplink L1 / L2 signaling or MAC signaling may be used for the notification. This may prevent, for example, loss of uplink data transmission from the preempted UE due to preemption transmission.

[0396] The gNB may include information regarding act / deact of the preemption transmission in the preemption instruction. The timing at which the preemption transmission is acted may be determined, for example, by further selecting whether or not to transmit from the above-mentioned transmission timings at which preemption communication may be performed. The preempted UE may use this information to determine whether or not preemption communication is being performed. Instead of information regarding act / deact, only information regarding act may be used. The preempted UE may determine that the preemption transmission is deacted based on the absence of information regarding act. This, for example, enables the preempted UE to secure more time resources available for uplink transmission.

[0397] The gNB may broadcast and / or notify the preemption instruction to UEs that may be preempted. The UEs that may be preempted may be all UEs served by the cell, or may be some of the UEs. Hereinafter, in this third embodiment, the notification from the gNB to the preempted UE may be broadcast and / or notified to the UEs that may be preempted, as described above.

[0398] Broadcast information may be used as a preemption command for all UEs served by the cell. Alternatively, a similar notification to the notification for the preempted UE described above may be used. The notification may be coded and / or modulated, for example, using an RNTI for system information. Alternatively, the notification may be coded and / or modulated, for example, using an identifier common within a beam of a base station used by the UE, for example, an identifier of the beam. UEs in the cell may obtain the notification using the RNTI. This may, for example, enable preemption commands for multiple UEs to be issued with a small amount of signaling.

[0399] A preemption command for some UEs served by a cell may be sent using a notification similar to the notification for the preempted UEs. The notification may be coded and / or modulated using, for example, an identifier of a group to which the some UEs belong (e.g., the RNTI of the group) instead of a C-RNTI. This may enable, for example, a preemption command for a plurality of UEs to be sent with a small amount of signaling. The group may be determined using, for example, a service (e.g., eMBB) used in the communication system, or may be determined by another method. For example, the identifier of the group may be provided using the identifier of the service.

[0400] As another example, the gNB may transmit the preemption instruction to UEs in some beams, which may be beams used by the UE performing the preemption communication or beams used by the UE to be preempted.

[0401] The UEs in some beams mentioned above may be, for example, all UEs in the beams. A notification similar to the notification to the preempted UEs mentioned above may be used as a preemption instruction for all UEs in the beam. The notification may be coded and / or modulated using, for example, an RNTI for system information instead of a C-RNTI. Alternatively, the notification may be coded and / or modulated using, for example, an identifier common within the beam, for example, an identifier of the beam. In the above, a beam identifier may be newly provided.

[0402] The UEs in the part of beams may be, for example, part of the UEs in the beam. A notification similar to the notification to the preempted UEs may be used as a preemption instruction for the part of the UEs in the beam. The notification may be encoded and / or modulated using, for example, an identifier of a group to which the part of the UEs belong (e.g., the RNTI of the group) instead of a C-RNTI. The group may be determined, for example, using a service (e.g., eMBB) used in the communication system, or may be determined by another method. For example, the identifier of the group may be given using the identifier of the service.

[0403] The UE to be preempted receives the preemption instruction. The UE may stop uplink transmission as an operation of uplink transmission overlapping with the preemption transmission. This, for example, makes it possible to ensure the reliability of the preemption transmission. The UE may not transmit (e.g., mask) the uplink data that was scheduled to be transmitted in the interval where the uplink transmission was stopped. Alternatively, the UE may reallocate the uplink data that was scheduled to be transmitted in the interval where the uplink transmission was stopped to other frequency / time resources and transmit the uplink data. As a method of the reallocation, the example shown in (5-3) disclosed above as information included in the preemption instruction transmitted from the gNB to the UE to be preempted may be applied.

[0404] As another example, the UE may perform uplink transmission that overlaps with the preemption transmission. As examples of uplink transmission that overlaps with the preemption transmission, the following (1) to (4) are disclosed.

[0405] (1) Transmit at low power.

[0406] (2) Transmission using thinned frequency resources.

[0407] (3) Transmitting time resources in a thinned manner.

[0408] (4) A combination of (1) to (3) above.

[0409] In the above (1), by reducing the uplink transmission power that overlaps with the preemption transmission, it becomes possible to ensure the reliability of the preemption transmission, for example.

[0410] In the above (2), the UE may thin out frequency resources in units of RB and transmit them, or may thin out frequency resources in units of RE and transmit them, thereby achieving, for example, the same effect as in (1).

[0411] In the above (3), the UE may thin out the time resource in units of symbols before transmitting, which can provide the same effect as in (1).

[0412] In the above (2) to (4), the preempted UE may redo the coding and modulation process, similar to the example shown in (5-3) disclosed as information included in the preemption command transmitted from the gNB to the preempted UE. The above-mentioned redoing method may also be applied to the example shown in (5-3) disclosed as information included in the preemption command transmitted from the gNB to the preempted UE. This makes it possible to prevent, for example, loss of uplink data transmission from the preempted UE due to preemption transmission.

[0413] One or more configuration patterns may be provided in advance for the operation of the uplink transmission overlapping with the preemption transmission in the UE. The pattern may be defined by a standard or determined by the gNB. The gNB may broadcast the determined configuration pattern to the UE or may notify the UE individually. The notification may be performed using RRC dedicated signaling.

[0414] In the above, the gNB may include an identifier indicating the configuration pattern in the preemption command sent to the UE. This makes it possible to reduce the frequency resources used to transmit the preemption command, for example, by reducing the transmission size of the preemption command.

[0415] As another example, the preemption instruction may not include an identifier indicating the setting pattern. For example, if there is only one setting pattern, the preemption instruction may not include an identifier indicating the setting pattern. This may further reduce the frequency resources used to transmit the preemption instruction.

[0416] The gNB may notify the preemption UE of an uplink grant, which may be sent to the UE without an SR from the UE.

[0417] The UE may perform preemption transmission using the uplink grant, or may not perform preemption transmission. If there is no uplink data to be transmitted as preemption, the UE may not perform preemption transmission.

[0418] The preemption instruction from the gNB to the preempted UE and the uplink grant from the gNB to the preempting UE may be sent using the same signaling. For example, a PDCCH common to multiple UEs may be used as the signaling. This makes it possible to reduce the amount of signaling from the gNB to each UE.

[0419] As another example, the preemption command from the gNB to the preempted UE and the uplink grant from the gNB to the preempting UE may be signaled differently. For example, the uplink grant may be transmitted earlier than the preemption command. This allows the preempting UE to secure time for coding and modulation processing after receiving the uplink grant.

[0420] In the above description, the symbol lengths used for the preemption command and the uplink grant may be different from each other. Alternatively, different TTIs may be used for the preemption command and the uplink grant. This makes it possible to apply the method described in the third embodiment even when, for example, the preempted UE and the preempting UE use different symbol lengths and / or TTIs from each other.

[0421] The gNB may periodically transmit the above-mentioned preemption notification to the preempted UE. The period may be determined by a standard, or may be determined by the gNB and notified to its subordinate UEs, or may be notified to each UE individually. RRC dedicated signaling may be used for the notification. The above-mentioned uplink grant from the gNB to the preempting UE may also be transmitted in the same manner as the preemption notification.

[0422] In the above, the preemption notification may be a preemption instruction.

[0423] The gNB may change the period. The gNB may change the period, for example, using RRC dedicated signaling. The changed period may be, for example, in units of radio frames, slots, minislots, symbols, or other time units. In this way, for example, when the gNB lengthens the period, the frequency with which the preempted UE receives a preemption command decreases. As a result, it is possible to reduce power consumption in the preempted UE.

[0424] The gNB may aperiodically transmit the preemption instruction to the preempted UE. The preempted UE may constantly receive the preemption instruction in the frequency resource to which the preemption instruction is transmitted, or may receive the preemption instruction at a preemption instruction transmission timing notified in advance by the gNB. The gNB may notify the preempted UE of the preemption instruction transmission timing, for example, by using RRC signaling.

[0425] As another example of a gNB aperiodically instructing a preemption indication to a preempted UE, the preempted UE may monitor a PDCCH for the preempting UE. The gNB may encode the PDCCH for the preempting UE with an identifier of a group of UEs including the preempting UE and the preempted UE. The identifier of the group may be, for example, a beam identifier, an RNTI for system information, or another identifier.

[0426] As another example, the gNB may notify the preempted UE in advance of the identifier of the preempting UE, for example, the C-RNTI. Instead of the identifier of the preempting UE, the identifier of a group of UEs that may perform preemption communication may be used. The preempting UE may belong to this group.

[0427] The preempted UE may acquire PDCCH information for the preempting UE using an identifier of a group of UEs including the preempting UE and the preempted UE, or an identifier of the preempting UE, such as the C-RNTI of the preempting UE, or an identifier of a group of UEs that may perform preemption communication.The preempted UE may use this information to determine whether to perform preemption transmission and the frequency and time resources to be used for the preemption transmission.This, for example, eliminates the need for new frequency resources for preemption indication, resulting in efficient use of the communication system.

[0428] The gNB may issue the preemption instruction to the preempted UE semi-persistently. This may, for example, reduce the number of times the gNB transmits a preemption instruction, thereby reducing power consumption at the gNB. The semi-persistent notification may include some or all of the information disclosed in the third embodiment as information included in the preemption instruction to the preempted UE. The semi-persistent notification may include information indicating the validity period of the notification, i.e., the period during which the notification includes information related to preemption transmission.

[0429] The gNB may perform the semi-persistent notification using predetermined frequency and time resources. For example, the semi-persistent notification may be performed using broadcast information, RRC dedicated signaling, MAC signaling, or L1 / L2 signaling. Alternatively, new frequency and time resources may be provided for transmitting the semi-persistent notification. The gNB may notify the preempted UE of information regarding the resources in advance.

[0430] The gNB may semi-statically transmit the preemption instruction to the preempted UE. This makes it possible to reduce the amount of signaling from the gNB to the preempted UE. The semi-static notification may include, as information contained in the preemption instruction to the preempted UE, some or all of the information (1) to (6) disclosed as information contained in the preemption instruction transmitted from the gNB to the UE to be preempted. The gNB may transmit the semi-static notification, for example, using broadcast information or RRC dedicated signaling.

[0431] The above-described methods may be combined. For example, the gNB may combine a semi-static preemption instruction and a preemption instruction using the PDCCH and notify the preempted UE of the combination. For example, the gNB may include information regarding the preemption transmission timing and frequency resource in the semi-static preemption instruction, or may include information regarding the operation of the preempted UE when the preemption transmission occurs. The gNB may include information regarding the act / deact of the preemption transmission in the preemption instruction using the PDCCH. The preempted UE may, for example, stop uplink transmission at the transmission timing when the preemption transmission is acted, using the semi-static preemption instruction and the preemption instruction using the PDCCH. This allows the gNB to issue a preemption instruction to the preempted UE with a small amount of signaling, for example.

[0432] As another example, the gNB may include, in the semi-static preemption instruction, information regarding the operation of the preempted UE when a preemption transmission occurs. The gNB may include, in the preemption instruction using the PDCCH, information regarding the preemption transmission timing and frequency resources. The preempted UE may, for example, stop uplink transmission at the preemption transmission timing using the semi-static preemption instruction and the preemption instruction using the PDCCH. This, in addition to the above-mentioned effects, enables flexible control of frequency and time resources in preemption communication.

[0433] As another example of a combination of the above-mentioned methods, the gNB may use a semi-persistent preemption indication and a preemption indication using a PDCCH. The information included in the semi-persistent preemption indication may be the same as the semi-static preemption indication in the above-mentioned example, or may include information regarding the validity period of the notification. This provides the same effect as described above.

[0434] Fig. 32 is a diagram showing an example in which a gNB sends an uplink preemption indication (UL preemption indication) to a preempted UE using a frequency resource different from the region used for transmitting and receiving downlink user data to the preempted UE. Fig. 32 shows an example of FDM. Fig. 32 also shows an example in which the preempted UE performs eMBB communication and the preempting UE performs URLLC communication. Fig. 32 also shows an example in which there are two timings in one slot in which preemption transmission can be performed.

[0435] 32 , the gNB transmits uplink preemption instructions 4001 and 4002 to the preempted UE. The preemption instructions may be transmitted using frequency resources different from PDCCH 4003 and PDSCH 4004. The preempted UE stops eMBB uplink communication 4005 at timing 4006 indicated by uplink preemption instruction 4001. The preempted UE also stops eMBB uplink communication 4005 at timing 4007 indicated by preemption instruction 4002. The preempted UE does not perform URLLC communication at timing 4006, and transmits URLLC communication 4008 at timing 4008.

[0436] Figure 33 is a diagram showing an example in which a gNB issues an uplink preemption instruction to a preempted UE via PDCCH. Figure 33 shows an example of FDM. Figure 33 also shows an example in which a preempted UE performs eMBB communication and a preempting UE performs URLLC communication. Figure 33 also shows an example in which there are two timings in one slot in which preemption transmission can be performed. In Figure 33, signals that overlap with those in Figure 32 are assigned the same numbers, and common explanations will be omitted.

[0437] 33 , an uplink preemption instruction 4101 is transmitted to a preempted UE using the first symbol of a PDCCH 4003. The uplink preemption instruction 4101 includes information about preemption communication timings 4006 and 4007. The preempted UE receives the uplink preemption instruction 4101 and acquires information about timings 4006 and 4007. The preempted UE stops eMBB uplink transmission at timings 4006 and 4007.

[0438] As the rest of FIG. 33 is the same as FIG. 32, the explanation will be omitted.

[0439] 33 shows an example in which the uplink preemption instruction 4101 is transmitted using the first symbol of the PDCCH 4003, but the first symbol does not have to be used. For example, the last symbol may be used, or an intermediate symbol may be used. Furthermore, the uplink preemption instruction 4101 may occupy part of the frequency resources of the PDCCH 4003.

[0440] 33 shows an example of FDM, but it may also be applied to TDM. For example, in TDM, the uplink preemption instruction 4101 may be included in the PDCCH 4003 and transmitted. The preemption communication timing indicated by the uplink preemption instruction 4101 may be included in the UL transmission timing in TDM. This makes it possible, for example, to transmit the uplink preemption instruction from the base station to the preempted UE even in TDM.

[0441] The gNB may provide one or more timings per slot for preemption transmission. The gNB may also concentrate the timings allocated to multiple UEs capable of preemption transmission into one or more. This makes it possible to secure uplink transmission resources for the preempted UE, even when there are many UEs capable of preemption transmission. Alternatively, the gNB may distribute the timings allocated to multiple UEs capable of preemption transmission among multiple UEs. This makes it possible to reduce the possibility of contention for preemption transmission timings between multiple UEs capable of preemption transmission.

[0442] The gNB may receive preemption transmissions from multiple preemption UEs in a contention-based manner. The gNB and the preemption UE may perform preemption retransmission processing using HARQ feedback. This allows the gNB to receive preemption transmissions in a contention-based manner.

[0443] Another solution is disclosed. The gNB notifies the preempted UE in advance of time resources and / or frequency resources on which preemption communication may occur. Information regarding the period of the preemption communication may be included in the notification. Information regarding uplink transmission operations in the UE that overlap with preemption transmission may be included in the notification. The information regarding the operations may be, for example, information indicating the suspension of uplink transmission, or information indicating (1) to (4) disclosed above as examples of uplink transmission overlapping with preemption transmission. The notification may be broadcast to UEs under the control of the gNB, or may be notified individually to the preempted UE. The individual notification may be RRC individual signaling, for example, signaling for RRC connection reconfiguration. The preempted UE may use the notification to stop uplink transmission, or may perform the operations indicated in (1) to (4) disclosed above as examples of uplink transmission overlapping with preemption transmission. This makes it possible to use frequency and time resources efficiently, for example, since dynamic preemption instructions to preempted UEs are no longer necessary.

[0444] This solution differs from the previously described solution using preemption indication in that the preempted UE is semi-statically notified of information regarding preemption transmission.

[0445] The gNB may notify the preemption UE of the notification. That is, the gNB may notify the preemption UE in advance of the time resources and / or frequency resources in which preemption communication may be performed. This facilitates scheduling in the preemption UE.

[0446] The gNB may notify the preemption UE of an uplink grant. The information included in the uplink grant and the behavior of the preemption UE after receiving the uplink grant may be the same as the solution using the preemption indication described above. This enables, for example, dynamic scheduling of the preemption UE according to the radio channel conditions, thereby ensuring the reliability of preemption communication.

[0447] Another solution is disclosed. The gNB applies no grant transmission to the preemption UE. That is, the gNB notifies the preemption UE of time resources and / or frequency resources on which preemption communication is permitted. The notification may include information on the period of preemption communication. The notification may include information on an uplink grant for the preemption UE. The notification may be broadcast to UEs under the control of the gNB, or may be notified individually to the preemption UE. The individual notification may be RRC individual signaling, for example, signaling for RRC connection reconfiguration.

[0448] Regarding the notification from the gNB to the preempted UE and the operation of the UE, the method shown in the solution for notifying the time resources and / or frequency resources where preemption communication may occur may be applied, which makes it possible to reduce the amount of signaling required for notification from the gNB to the preempted UE.

[0449] The notification from the gNB to the preempted UE and the broadcast and / or notification from the gNB to the preempting UE may be different signaling. Alternatively, both pieces of information may be included in the same signaling. This can reduce the amount of signaling from the gNB to each UE.

[0450] As another example of applying no grant transmission, the gNB may broadcast or notify the preemption UE in advance of information regarding transmission timing and / or transmission power at which preemption communication may be performed. The transmission timing may be information regarding a transmission period. The information regarding the transmission timing may be in units of minislots or symbols. RRC signaling may be used for the broadcast or notification.

[0451] The gNB may notify the preemption UE of information regarding act / deact of the preemption transmission. The timing at which the preemption transmission is acted may be determined, for example, by the gNB selecting whether or not to transmit from the above-mentioned transmission timings at which preemption communication may be performed. Instead of the information regarding act / deact, only information regarding act may be used. The preemption UE may determine that the preemption transmission is deacted by using the absence of information regarding act.

[0452] The gNB may include information about resources used for preemption transmission in the information about act / deact of preemption transmission. The resources may be information about time resources or information about frequency resources. The gNB may include information necessary for modulation and / or encoding of preemption transmission in the information about act / deact of preemption transmission. The information necessary for modulation and / or encoding may be, for example, information about a modulation scheme, information about a coding rate, or information about a HARQ process number.

[0453] The gNB may transmit information regarding activation / deactivation of preemption transmission using a PDCCH for the preemption UE. Alternatively, new frequency / time resources may be provided for transmitting the information. The gNB may notify the preemption UE in advance of information regarding the new frequency / time resources.

[0454] The gNB may notify the preempted UE of information regarding preemption transmission. The information may be the same as the preemption instruction disclosed in the third embodiment. The information may include, for example, information regarding transmission timing. The information regarding transmission timing may be, for example, information regarding the timing at which the preemption transmission was acted. The information may include some or all of the act / deact information notified from the gNB to the preempting UE. The preempted UE may use the information to determine the timing at which a preemption transmission is likely to occur.

[0455] The gNB may transmit information regarding preemption transmission to the preempted UE using the PDCCH for the preempted UE. Alternatively, new frequency / time resources may be provided for transmitting the information. The gNB may notify the preempted UE in advance of information regarding the new frequency / time resources.

[0456] According to the third embodiment, it is possible to reduce delays in preemption communication and also to ensure reliability in preemption communication.

[0457] Variation 1 of embodiment 3 The following problem occurs in uplink preemption transmission. That is, when the gNB notifies the preempted UE of information about the timing at which preemption transmission may occur, the preempted UE stops uplink transmission or transmits at a lower power even in frequency and time resources where preemption transmission does not actually occur. This causes a problem of reduced uplink transmission efficiency for the preempted UE.

[0458] Solutions to the aforementioned problems are disclosed below.

[0459] The preemption UE notifies the gNB of information indicating a request for preemption transmission. For example, a predetermined code may be used as the information. The predetermined code may be generated using a sequence that does not require or facilitates encoding and decoding processes. For example, the predetermined code may be a ZC (Zadoff-Chu) code, an m-sequence, or a Hadamard code. The preemption UE may notify the gNB of the information immediately after the generation of preemption transmission data.

[0460] Examples of the information relating to the predetermined code are shown below as (1) to (8).

[0461] (1) A sequence in a ZC code (e.g., value q).

[0462] (2) Cyclic shift.

[0463] (3) Number of symbols.

[0464] (4) Number of transmissions.

[0465] (5) Information about frequency hopping.

[0466] (6) Information about sequence hopping.

[0467] (7) Information regarding transmission timing.

[0468] (8) A combination of (1) to (7) above.

[0469] The above (1) may be, for example, the value of the root index in the ZC code.

[0470] Regarding the above (3), the number of symbols may be, for example, one symbol or multiple symbols. This allows the code to be notified quickly by using, for example, one symbol. Furthermore, by using, for example, multiple symbols, the sequence length of the code can be increased, thereby improving reliability.

[0471] According to the above (4), for example, by transmitting the code multiple times, it is possible to improve the reliability of the notification of the code.

[0472] The above (5) makes it possible to improve the reliability of the notification of the code by, for example, frequency diversity.

[0473] The above (6) makes it possible to improve the reliability of notification of the code by avoiding interference when the same code is transmitted from other UEs and / or other base stations, for example.

[0474] The information (7) above may be, for example, information regarding the time resolution at which the UE can transmit the code. The time resolution may be, for example, per symbol, per minislot, or per slot. This allows the code to be notified quickly when the time resolution is, for example, per symbol.

[0475] The information about the predetermined code may be determined by a standard. For example, the information may be common among UEs under the control of a gNB. The information may be determined for each UE individually. The information may be determined using a UE identifier (e.g., UE-ID). This may, for example, eliminate the need for a process of assigning codes to UEs, thereby reducing the amount of processing related to code assignment.

[0476] As another example, the gNB may determine information regarding the predetermined code and notify the UE. The information may be common among UEs under the control of the gNB. The information may be determined using an identifier indicating the base station (e.g., gNB-ID) or an identifier indicating the cell (e.g., cell ID). Alternatively, the gNB may assign the information to each UE individually. The gNB may broadcast the information to each UE, or may notify the information semi-statically using RRC dedicated signaling. For example, the amount of signaling related to the notification of the information can be reduced. Alternatively, the information may be notified dynamically using MAC signaling. For example, reliability can be ensured by retransmission control, and flexible allocation according to the status of neighboring cells and subordinate UEs can be made. Alternatively, L1 / L2 signaling may be used. For example, rapid notification is possible.

[0477] Regarding the information about the predetermined code, one piece of information may be used for each UE, or multiple pieces of information may be used. As an example of using multiple codes, codes may be selected based on information about the amount of data in uplink preemption transmission. This enables, for example, the gNB to perform flexible scheduling using the amount of data in uplink preemption transmission.

[0478] The band in which the preemption UE transmits the predetermined code may be the entire band available to the preemption UE, or a part of it. A band consisting of one or more RBs may be used at intervals. A band consisting of one or more REs may be used at intervals. A combination of both of the above may also be used. That is, within a band consisting of one or more RBs at intervals, the predetermined code may be allocated to a band consisting of one or more REs at intervals. This enables, for example, flexible band allocation.

[0479] The band in which the preempting UE transmits the predetermined code may be different from the band usable by the preempted UE. That is, the uplink signal transmission from the preempted UE and the transmission of the predetermined code from the preempted UE may be performed in different frequency bands. This, for example, can reduce interference power in reception of the predetermined code by the gNB. As a result, it is possible to improve the reliability of transmission of the predetermined code from the preempted UE.

[0480] As another example, the band in which the preempting UE transmits the predetermined code may include part or all of the band available to the preempted UE. That is, the uplink signal transmission from the preempted UE and the transmission of the predetermined code from the preempted UE may be performed in frequency bands that at least partially overlap each other. The gNB may simultaneously receive the predetermined code and the uplink signal. The gNB may separate the predetermined code from the uplink signal. In the separation, the gNB may extract the predetermined code from the simultaneously received signals using the same pattern as the predetermined code. The gNB may process the remaining extracted signal as the uplink signal from the preempted UE. This, for example, enables efficient use of frequency resources in the communication system.

[0481] The band in which the preemption UE transmits the predetermined code may be determined by a standard, or may be determined by the gNB and notified to the UE. The notification method may be the same as the notification method for the predetermined code described above.

[0482] The timing at which the preemption UE transmits the predetermined code may be determined in advance by a standard. For example, the preemption UE may transmit the code at a symbol a predetermined period before the start of preemption transmission. As another example, the preemption UE may transmit the code at a predetermined symbol in a minislot one or more minislots before the minislot in which preemption transmission is performed.

[0483] The symbol preceding the predetermined period in the above description may be multiple symbols. The preemption UE may transmit the predetermined code using some or all of the multiple symbols. For example, if some of the multiple symbols include a timing at which preemption transmission is not possible, the preemption UE may transmit the predetermined code using symbols from the multiple symbols excluding the timing at which preemption transmission is not possible. This, for example, can improve flexibility in setting preemption transmission. As another example, the preemption UE may repeatedly transmit the predetermined signal using all of the multiple symbols. This, for example, can improve reliability in transmission of the predetermined code from the preemption UE.

[0484] As another example, the gNB may determine the timing at which the preempting UE transmits the predetermined code. The gNB may broadcast or individually notify the timing to its subordinate UEs. For this notification, RRC dedicated signaling may be used. In determining the timing at the gNB, the gNB may use the processing capability of the gNB related to receiving the code, or the processing capability of the UE related to transmitting the code, or the processing capability of the gNB related to transmission and / or the processing capability of the UE related to reception of the predetermined code transmitted from the gNB to the preempted UE, as described below. The processing capability of the UE related to transmission of the code and / or the processing capability of the UE related to reception of the predetermined code transmitted from the gNB to the preempted UE, as described above, may be included in, for example, UE capabilities. This allows the gNB to determine the timing so as to meet the processing time of the gNB and the UE for the code, for example.

[0485] The preempting UE may transmit the predetermined code at a timing different from the transmission timing of the DMRS and / or PUCCH and / or SRS from the preempted UE. The aforementioned transmission at a different timing may be applied, for example, when the predetermined code and the DMRS, PUCCH, or SRS are transmitted using the same frequency resource. The preempting UE may change the transmission timing of the predetermined code. The change in the transmission timing of the predetermined code may be performed, for example, within a range of multiple symbols that the predetermined code from the preempted UE can transmit. This allows, for example, the preempting UE to quickly notify the gNB of the predetermined code. The gNB may notify the preempting UE in advance of information regarding the transmission timing of the DMRS and / or PUCCH and / or SRS from the preempted UE. Alternatively, the information regarding the timing may be predetermined in a standard. This allows, for example, the preempting UE to recognize the timing at which the predetermined code can be transmitted.

[0486] In the above, the preempting UE may not transmit the predetermined code within a transmittable range, for example, if there is no timing different from the transmission timing of the DMRS and / or PUCCH and / or SRS from the preempted UE. The preempting UE may transmit the predetermined code within a next transmittable range. This may avoid, for example, complex control related to preemption transmission in a communication system.

[0487] The method for changing the transmission timing of the predetermined code may be determined in advance by a standard, and may be, for example, a method of shifting the transmission timing of the predetermined code forward by one symbol at a time, a method of shifting the transmission timing of the predetermined code backward by one symbol at a time, or a combination of both methods, within a range of a plurality of symbols that can transmit the predetermined code.

[0488] As another example of a method for changing the transmission timing of the predetermined code, the gNB may individually notify the preemption UE of the change method, which may be, for example, RRC individual signaling, MAC signaling, or L1 / L2 signaling.

[0489] As another example, the transmission timing of the predetermined code within a slot may be predetermined by a standard, or may be broadcast or notified in advance from the gNB to the preempting UE. The transmission timing of the DMRS and / or PUCCH and / or SRS from the preempted UE may be set to a timing excluding the transmission timing of the predetermined code. This makes it possible to avoid, for example, the complexity of controlling preemption transmission in a communication system.

[0490] As another example, the preempting UE may transmit the predetermined code at the same timing as the DMRS transmission timing from the preempted base station. The above-mentioned transmission at the same timing may be applied, for example, when the predetermined code and the DMRS are transmitted using different frequency resources.

[0491] The gNB may assign different sequences to the predetermined code and the DMRS. This assignment may be applied, for example, when the predetermined code and the DMRS are performed using the same frequency resource. The gNB may notify the preempted UE and / or the preempting UE of the assignment. This notification may be, for example, RRC dedicated signaling, MAC signaling, or L1 / L2 signaling. This allows, for example, the gNB to simultaneously receive both the predetermined code and the DMRS.

[0492] As another example, the predetermined code and the DMRS may be frequency-multiplexed with each other. Frequency multiplexing may be performed, for example, before a subcarrier, for each of a plurality of subcarriers, for each resource element group (REG), or by other methods. The gNB may notify the preempted UE and / or the preempting UE of the frequency-multiplexing method. The notification may be, for example, RRC dedicated signaling, MAC signaling, or L1 / L2 signaling. This allows the gNB to simultaneously receive both the predetermined code and the DMRS, for example.

[0493] The gNB receives a predetermined code transmitted from the preemption UE. Upon receiving the code, the gNB recognizes a request for preemption transmission.

[0494] The gNB notifies the preempted UE of information indicating a preemption transmission. For example, a predetermined code may be used as the information. The predetermined code may be the same as the code transmitted from the preempting UE to the gNB as information indicating a preemption transmission request. The code used in the information transmitted from the gNB to the preempted UE may be the same as or different from the code used in the information transmitted from the preempting UE to the gNB. The gNB may transmit the information to the preempted UE immediately after recognizing the request for preemption transmission.

[0495] The information about the predetermined code may be the same as the information about the code transmitted from the preemption UE to the gNB. The method of determining the information about the predetermined code and the method of broadcasting and / or notifying the gNB to the subordinate UE may also be the same.

[0496] Regarding the information about the predetermined code, one piece of information may be used for each UE, or multiple pieces of information may be used. As an example of using multiple codes, different codes may be used using information about frequency resources used for preemption transmission. This enables, for example, the gNB to flexibly schedule using the amount of data in uplink preemption transmission.

[0497] The timing of transmitting the predetermined code may be the same as the timing of transmitting the predetermined code from the preemption UE.

[0498] The band in which the gNB transmits the predetermined code may be the same as the band in which the preempting UE transmits the predetermined code. For example, the band in which the gNB transmits the predetermined code may be the entire band available to the preempted UE, or a part of it. In another example, the band in which the gNB transmits the predetermined code may be near the center of the band used by the gNB. By using the same band as the synchronization signal or broadcast information channel, for example, all UEs under the gNB can receive the above-mentioned code in common.

[0499] The preempted UE receives a predetermined code transmitted from the gNB. Upon receiving the code, the preempted UE recognizes the occurrence of a preemption transmission.

[0500] Upon receiving the code, the preempted UE may stop uplink transmission that overlaps with the preemption transmission, or may perform the operations (1) to (4) disclosed as examples of uplink transmission that overlaps with the preemption transmission in the third embodiment. The operation of the preempted UE regarding uplink transmission that overlaps with the preemption transmission may be determined by a standard, or may be notified in advance by the gNB to the preempted UE, or may be notified individually. The method shown in the third embodiment may be applied to the above-mentioned standard-based determination, notification, or individual notification.

[0501] The gNB notifies the preemption UE of information regarding an uplink grant for preemption transmission. The information may be, for example, an uplink grant using a PDCCH for the preemption UE. As another example, a predetermined code may be used for the information. The predetermined code may be the same as the code transmitted from the preemption UE to the gNB as information indicating a request for preemption transmission. The code used for the information transmitted from the gNB to the preemption UE may be the same as or different from the code used for the information transmitted from the preemption UE to the gNB.

[0502] The information about the predetermined code notified from the gNB to the preemption UE may be the same as the information about the code transmitted from the preemption UE to the gNB. The method of determining the information about the predetermined code and the method of broadcasting and / or notifying the gNB to the subordinate UE may also be the same.

[0503] Regarding the information regarding the predetermined code notified from the gNB to the preemption UE, one piece of information may be used for each UE, or multiple pieces of information may be used. As an example of using multiple codes, different codes may be used using information regarding frequency resources used for preemption transmission. As another example, different codes may be used using information regarding the transmission power of preemption communication. This enables, for example, the gNB to perform flexible scheduling in uplink preemption transmission. The gNB may notify the preemption UE of the above-mentioned multiple pieces of information in advance.

[0504] Regarding the timing of transmission of the predetermined code notified from the gNB to the preemption UE, a method similar to the timing of transmission of the predetermined code by the preemption UE may be applied.

[0505] The band in which the gNB transmits the predetermined code to the preemption UE may be the same as the band in which the preemption UE transmits the predetermined code. For example, the entire band available to the preemption UE may be used, or a portion of the band may be used. In another example, the center of the band used by the gNB may be used. By using the same band as that for the synchronization signal or broadcast information channel, for example, UEs under the control of the gNB can commonly receive the above-mentioned code.

[0506] The preemption UE performs preemption transmission using the information about the uplink grant described above.

[0507] The preemption UE may determine that the preemption request has failed by not receiving the information about the uplink grant. For example, the preemption UE may determine that the preemption request has failed by not receiving the information about the uplink grant by a predetermined time.

[0508] The preemption UE may retransmit the preemption request. This retransmission may be performed, for example, when the preemption UE determines that the preemption request has failed. The preemption UE may retransmit the preemption request immediately after the determination, at a timing when the preemption request can be transmitted. This allows, for example, the preemption UE to quickly transmit the preemption request.

[0509] A preemption UE may be provided with a retransmission prohibition timer for a preemption request. The preemption UE may not transmit or retransmit a preemption request until the retransmission prohibition timer expires. This can prevent, for example, congestion of frequency and time resources due to repeated retransmission of a preemption request.

[0510] The preemption request retransmission prohibition timer may be started, for example, upon transmission of the preemption request. The timer may be stopped, for example, upon reception of an uplink grant from the gNB.

[0511] The value of the timer may be predetermined by a standard, or may be determined by the gNB and broadcast or individually notified to the preemption UE. The notification may be via RRC signaling, MAC signaling, or L1 / L2 signaling. By determining the value of the timer by the gNB, flexible control according to the usage status of frequency and time resources becomes possible, for example.

[0512] Fig. 34 is a diagram showing an example in which a predetermined code is used as information indicating a preemption request. Fig. 34 shows an example of FDM. Fig. 34 also shows an example in which a preempted UE performs eMBB communication and a preempting UE performs URLLC communication. In Fig. 34, signals common to Fig. 32 are assigned the same numbers, and common descriptions will be omitted.

[0513] In FIG. 34, the preempting UE transmits code 4201 indicating a preemption request to the gNB. Code 4201 may be transmitted using the band used for preemption communication, or may be transmitted using a band different from that band. The gNB receives code 4201 and recognizes the preemption request. The gNB transmits an uplink preemption instruction 4202 to the preempted UE. The uplink preemption instruction 4202 may be the same code as code 4201, or may be the same as that in embodiment 3. Furthermore, the uplink preemption instruction 4202 may be transmitted using the bands used for PDCCH 4003 and PDSCH 4004, or may be transmitted using a band different from that band.

[0514] This first modification may be used in combination with the third embodiment. For example, the base station notifies the preempted UE, and the gNB notifies the preempted UE, in advance of time resources and / or frequency resources where preemption communication may occur. The notification may include information about uplink transmission operations in the UE that overlap with preemption transmission. The preempted UE may transmit a predetermined code shown in this first modification to the base station, and the base station may transmit the predetermined code shown in this first modification to the preempted UE. Upon receiving the predetermined code, the preempted UE may stop uplink transmission, or may perform the operations shown in (1) to (4) disclosed as examples of uplink transmission overlapping with preemption transmission. The preempted UE may continue uplink transmission if it does not receive the predetermined code. This allows the preempted UE to perform uplink transmission in frequency and time resources where preemption transmission does not actually occur, thereby ensuring uplink transmission efficiency for the preempted UE.

[0515] This modification 1 makes it possible to quickly notify the gNB because it eliminates or simplifies the decoding process of the SR, the encoding process of the uplink grant, and the encoding process of the uplink preemption instruction. Also, in the preempted UE, it becomes possible to perform uplink transmission in frequency / time resources where no preemption transmission actually occurs, thereby ensuring the efficiency of uplink transmission in the preempted UE.

[0516] Embodiment 4 In LTE-NR coexistence on the same downlink carrier, the gNB transmits NR signals using MBFSN subframes in LTE. The gNB transmits NR signals using MBSFN subframes. The gNB may transmit NR signals using non-MBSFN subframes. The gNB may use minislots to transmit NR signals.

[0517] In the above description, the gNB and the LTE base station (eNB) may or may not be base stations that configure a DC for a certain UE. For example, the gNB and the eNB may be base stations installed in close proximity to each other. This makes it possible to reduce interference from the gNB in ​​a UE that only supports LTE.

[0518] The NR signal may be an SS signal, a PBCH, or both. The gNB may transmit the SS and PBCH in one block (hereinafter referred to as an SS block) in each beam.

[0519] The gNB may transmit SS signals and PBCH signals suddenly (hereinafter, sometimes referred to as SS bursts). For example, the gNB may transmit SS signals and / or PBCH signals in each beam at a predetermined time. The SS signals and / or PBCH signals at the predetermined time may be transmitted at other predetermined intervals. The SS signals and / or PBCH signals at the predetermined time may be transmitted in SS blocks.

[0520] When the above-mentioned method is applied, the following problem occurs: NR SS burst signals collide with LTE non-MBSFN signals, such as synchronization signals, broadcast information, and paging information. As a result, in LTE-NR coexistence, the UE cannot establish synchronization with the eNB and / or gNB.

[0521] Solutions to the aforementioned problems are disclosed below.

[0522] Priority is established between LTE non-MBSFN subframe signals and NR SS burst signals. For example, in a section where both signals collide, only one of the signals is transmitted. The aforementioned LTE non-MBSFN subframe signals may be, for example, LTE synchronization signals, LTE broadcast channels, or LTE paging signals. The aforementioned NR SS burst signals may be, for example, NR synchronization signals or NR broadcast channels.

[0523] For example, signals in LTE non-MBSFN subframes may be prioritized. This can reduce interference in LTE non-MBSFN subframes, for example. The gNB may not transmit all or some of the SS burst signals in subframes that overlap with LTE non-MBSFN subframes. The overlapping subframes mentioned above may instead be overlapping slots, overlapping minislots, or overlapping symbols. As another example, the gNB may not transmit only the NR SS burst signals that overlap with signals in non-MBSFN subframes. This can prevent unnecessary SS burst suspension.

[0524] The gNB may transmit an NR SS burst signal that overlaps with an LTE non-MBSFN subframe signal. These two signals may be separable from each other, for example, one of the signals may have a predetermined pattern. Separable signals may be, for example, a combination of an LTE SS and an NR PBCH, a combination of an LTE PBCH and an NR SS, or a combination of an LTE paging signal and an NR SS. The UE may receive the overlapping signals and separate each signal. For example, the UE may extract a signal with a predetermined pattern and obtain the difference between the original received signal and the extracted signal as the other signal. This allows the UE to receive both LTE and NR signals, for example.

[0525] The eNB may change the timing of paging transmission to the UEs under its control. The change may, for example, aggregate the timing of paging transmission to the UEs under its control into one or more timings. This, for example, can reduce the overlap between the NR SS burst signal and the LTE paging transmission timing, thereby eliminating the need to stop SS burst transmission in the gNB and reducing the NR SS burst transmission that interferes with the eNB signal.

[0526] As an example of changing the paging transmission timing, the POs of the UEs under its control may be aggregated into one value. This makes it possible to avoid, for example, overlap between NR SS burst transmission and LTE paging transmission timing. As an example of a method of aggregating the POs into one value, the value of parameter Ns, which indicates the number of subframes to which paging signals are allocated in one radio frame, may be set to 1, as described in Non-Patent Document 17 (3GPP TS 36.304 V14.4.0). The eNB may set the value of parameter nB described in Non-Patent Document 17 (3GPP TS 36.304 V14.4.0) to 1 or less times T, thereby setting the value of parameter Ns to 1. The eNB may broadcast the changed value of parameter nB to the UEs under its control. For example, SIB2 may be used for the above-mentioned broadcast (see Non-Patent Document 18 (3GPP TS 36.311)). This allows, for example, the eNB to aggregate the POs of the UEs under its control into one way with a small amount of signaling.

[0527] The above-mentioned change in paging transmission timing may be, for example, a change in paging frame (PF), a change in paging occasion (PO), a change in paging transmission cycle, or a combination of two or more of the above.

[0528] When changing the paging transmission timing, the eNB may change a parameter used to determine the paging transmission timing. The parameter may be, for example, a UE-ID. The eNB may notify the UE of information related to the parameter change.

[0529] The eNB may increase the number of paging destination UEs that can be transmitted in one paging transmission timing. The increased number may be determined in advance by a standard, for example. This allows the eNB to transmit paging to a large number of UEs in a small number of paging transmission timings.

[0530] The eNB may notify the information to neighboring eNBs. The neighboring eNBs may be, for example, multiple eNBs that belong to the same tracking area as the eNB. The multiple eNBs may use the information to page the UE. This allows for smooth paging operations when, for example, mobility occurs in the UE.

[0531] The eNB may notify the information to a higher-level network device. The notification may be made using an interface between the higher-level network device and the base station. The higher-level network device may be an AMF or an SMF. The higher-level network device may transmit a notification to the eNB indicating whether to accept or reject the parameter change.

[0532] The upper network device may notify the information to a subordinate eNB. The subordinate eNB may be, for example, a plurality of eNBs that belong to the same tracking area as the eNB. The plurality of eNBs may use the information to page the UE. This allows smooth paging operations when, for example, mobility occurs in the UE.

[0533] The gNB may acquire information about non-MBSFN subframes of LTE. The following (1) to (5) are disclosed as information about non-MBSFN subframes of LTE.

[0534] (1) LTE frame timing.

[0535] (2) Information about LTE SS.

[0536] (3) Information regarding the LTE communication method.

[0537] (4) Information about paging timing.

[0538] (5) A combination of (1) to (4) above.

[0539] The gNB may acquire the LTE frame timing described in (1) above using the cell search described in the first embodiment. The gNB may have a function for performing the cell search. The gNB may set the timing for performing the cell search. As another example, the gNB may request information regarding the difference between the frame timing of LTE and NR from the eNB. The eNB may notify the gNB of the information. The request and / or the notification may be made using an inter-base station interface, for example, an Xn interface. The eNB may acquire the NR frame timing. For example, the eNB may acquire the NR frame timing using the cell search. This enables the gNB to acquire information regarding LTE non-MBSFN subframes, for example.

[0540] The gNB may request the information in (2) above from the eNB. The eNB may notify the gNB of the information in (2) above. The request and / or notification may be made using an inter-base station interface, for example, an Xn interface. The information in (2) above may be, for example, information about a code sequence and a cyclic shift of an LTE PSS, or information about a code sequence and a cyclic shift of an LTE SSS. The gNB may perform a cell search using the information in (2) above. This, for example, enables the gNB to quickly perform a cell search process. Furthermore, for example, it becomes possible to prevent erroneous detection of an LTE cell in the gNB.

[0541] As another example, the gNB may obtain the information (2) above using cell search, which may reduce the amount of signaling between base stations, for example.

[0542] The information in (3) above may include information about the LTE duplex mode (e.g., TDD or FDD) or half-duplex mode, or may include information about the cyclic prefix (e.g., the length of the cyclic prefix duration). The gNB may request the information in (3) from the eNB. The eNB may notify the gNB of the information. The request and / or notification may be made via an inter-base station interface, for example, the Xn interface. The gNB may use the information to derive the position of a signal in a non-MBFSN LTE subframe. This allows, for example, the gNB to quickly obtain information about a non-MBSFN LTE subframe.

[0543] As another example of the above (3), the gNB may obtain the information of the above (3) from LTE broadcast information. This makes it possible to reduce the amount of signaling between base stations, for example.

[0544] The information in (4) above may include, for example, information on the paging frame (PF), paging occasion (PO), and paging cycle used by the eNB. The gNB may request this information from the eNB. The eNB may notify the gNB of this information. The eNB may notify the information after a request from the gNB, or may notify the information when a change occurs. The gNB may use this information to transmit an SS burst signal in a non-MBFSN subframe. For example, the gNB may transmit an SS burst signal in a subframe that the eNB does not allocate to paging information. This makes it possible to ensure the timing of SS burst signal transmission in the gNB.

[0545] The information (4) above may include, for example, information on subframes that the eNB does not actually use for paging transmission. The information (4) above may also be information on subframes that the eNB actually uses for paging transmission. The gNB may use this information to transmit SS burst signals in subframes that are not actually used for paging transmission. This makes it possible, for example, to ensure the timing of SS burst signal transmission in the gNB.

[0546] The upper network device may notify the gNB of information regarding paging from the eNB to the UE. The notification of this information may be performed when paging to the UE occurs. The upper network device may notify the eNB and the gNB of this information simultaneously, or at different times. The gNB may use this notification to derive a subframe in which a paging signal is actually transmitted from the eNB to the UE. The gNB may transmit an SS burst signal in a subframe other than the derived subframe. For example, it becomes possible to ensure the timing of SS burst signal transmission in the gNB.

[0547] The gNB may not transmit some signals in the SS burst. For example, the gNB may transmit fewer SS blocks in the SS burst. This may reduce interference in LTE non-MBFSN subframes, for example.

[0548] The gNB may rearrange the order of the SS blocks constituting the SS burst. The rearrangement of the order of the SS blocks may be performed semi-statically or periodically. This allows the gNB to transmit all SS blocks to the UE, for example, even if a collision occurs with a signal in a non-MBFSN subframe of LTE.

[0549] In the above, the order of SS blocks may be rearranged on a subframe-by-subframe basis. For example, if SS blocks #0 and #1 are transmitted in subframe #0 and SS blocks #2 and #3 are transmitted in subframe #1, the order of SS blocks may be rearranged so that SS blocks #2 and #3 are transmitted in subframe #0 and SS blocks #0 and #1 are transmitted in subframe #1. This, for example, makes it easier to control the rearrangement.

[0550] As another example, the SS blocks may be rearranged in slot units, which makes it possible to rearrange the order of the SS blocks even when, for example, the symbol lengths of LTE and NR are different.

[0551] As another example, SS blocks may be rearranged on an SS block basis, which allows for flexible control in the gNB, for example.

[0552] Figure 35 is a diagram showing an example of rearrangement of SS blocks in an NR SS burst. In Figure 35, the upper part shows an LTE signal, and the lower part shows an NR signal. In both the upper and lower parts, the left 5 milliseconds portion shows the signal before the SS block rearrangement, and the right 5 milliseconds portion shows the signal after the SS block rearrangement. Figure 35 shows a case where the NR symbol length is the same as LTE, and the number of NR SS blocks is 8.

[0553] In FIG. 35, SS 4501, PBCH 4502, PDCCH 4503 in the paging signal, and paging signal 4504 are transmitted as signals in non-MBSFN subframes from the eNB.

[0554] Before the SS block rearrangement in Figure 35, SS block #0 (SS block 4510) and SS block #1 (SS block 4511) located in subframe #0 are not transmitted because they overlap with SS 4501 and PBCH 4502. SS block #2 (SS block 4512) to SS block #7 (SS block 4517) located in subframes #1 to #4 are transmitted.

[0555] 35, the SS blocks of subframe #0 and subframe #1 are rearranged. As a result, SS block #2 (SS block 4522) and SS block #3 (SS block 4523) located in subframe #0 are not transmitted, and SS block #0 (SS block 4520), SS block #1 (SS block 4521), and SS block #4 (SS block 4514) to SS block #7 (SS block 4517) located in subframes #1 to #4 are transmitted.

[0556] After the SS block rearrangement in Figure 35, once another rearrangement period has elapsed, the arrangement may return to the arrangement before the SS block rearrangement, which makes it possible to prevent, for example, a situation in which transmission of any of SS blocks #0 to #3 continues to be suspended.

[0557] Figure 36 is a timing diagram showing the transmission of NR SS blocks that do not overlap with LTE non-MBSFN signals. Figure 36 shows the overlap of LTE non-MBFSN subframes and NR SS bursts when the LTE and NR symbol lengths are different. Figure 36 shows the case where the NR symbol length is half that of LTE, i.e., the NR subcarrier spacing is 30 kHz, twice that of LTE.

[0558] In Figure 36, SS block #0 (SS block 4610) in NR is transmitted because it does not overlap with LTE SS 4601 or PBCH 4602. NR SS block #1 (SS block 4611) is not transmitted because it overlaps with LTE SS 4601. NR SS block #2 (SS block 4612) and SS block #3 (SS block 4613) are not transmitted because they overlap with LTE PBCH 4602.

[0559] A method of rearranging SS blocks may be to rotate the SS blocks. For example, after repeating SS bursts in the order of SS blocks #0, #1, #2, #3, #4, #5, #6, and #7 a certain number of times, SS bursts in the order of SS blocks #6, #7, #0, #1, #2, #3, #4, and #5 may be repeated a certain number of times, and then SS bursts in the order of SS blocks #4, #5, #6, #7, #0, #1, #2, and #3 may be transmitted. This, for example, can equalize the opportunity to capture SS blocks in each beam, thereby reducing the maximum time required for terminal synchronization.

[0560] In the method of circulating SS blocks, the unit of circulation may be every SS block, every slot, or every subframe, and the direction of circulation may be forward or backward in the time direction.

[0561] The gNB may notify the UE of information regarding the reordering of the NR SS blocks, which allows the UE to continue capturing the NR SS blocks even after the reordering occurs, for example.

[0562] The information may be included in, for example, system information. The information may be included in minimum SI. The information may be broadcast to subordinate UEs or notified as Remaining Minimum System Information (RMSI). Alternatively, the information may be broadcast to subordinate UEs as Other SI or notified individually.

[0563] In broadcasting or notifying the information, a carrier different from the NR carrier in which rearrangement of the SS block order occurs may be used. This allows, for example, the UE to quickly grasp the information. Alternatively, the NR carrier in which rearrangement of the SS block order occurs may be used. This, for example, eliminates the need for other multiple NR carriers to broadcast or notify information regarding rearrangement of the SS block, thereby reducing the amount of signaling.

[0564] For example, the eNB may broadcast or notify the information. The eNB may use the same method for broadcasting or notifying the information as the gNB. This allows the UE to quickly grasp the information, for example.

[0565] Alternatively, neither the gNB nor the eNB may report this information. The UE may automatically reacquire the SSB blocks after rearrangement of the NR SS blocks. This can reduce the amount of signaling.

[0566] Examples of information included in the information include the following (1) to (4).

[0567] (1) Information about the period of SS block sorting.

[0568] (2) Information about the SS blocks to be reordered.

[0569] (3) Information about how to sort.

[0570] (4) A combination of (1) to (3) above.

[0571] Regarding (1) above, the period may be, for example, in units of subframes. As another example, it may be a value in units of the maximum duration of an SS burst (for example, 5 milliseconds). As another example, it may be a value in units of radio frames (for example, 10 milliseconds) or a value in units of the transmission period of an SS burst.

[0572] Regarding (2) above, the information may be, for example, the numbers of the SS blocks to be rearranged. For example, in the example of FIG. 35 above, the information may be SS blocks #0, #1 and SS blocks #2, #3. This allows, for example, flexible rearrangement of SS blocks. As another example, slot numbers may be used. This allows, for example, rearrangement even when LTE and NR have different symbol lengths. As another example, subframe numbers may be used. This allows, for example, a reduction in the amount of processing required for rearrangement.

[0573] As another example of the above (2), the information may be information about the unit of rearrangement. Information about the unit of rearrangement may be applied, for example, when cyclic rearrangement is used. The unit of rearrangement may be, for example, an SS block unit, a slot unit, or a subframe unit.

[0574] Regarding the above (3), the information may be, for example, information indicating the replacement of SS blocks or information indicating a cyclic rearrangement. The information may include information indicating whether to circulate forward or backward in the time direction.

[0575] The gNB may automatically change the paging transmission timing for a beam in accordance with the rearrangement of the SS blocks corresponding to the beam. The UE may automatically change the paging reception timing in accordance with the rearrangement of the SS blocks. The correspondence between the order of the SS blocks and the paging transmission timing may be determined by a standard. This makes it possible, for example, to maintain consistency in the relationship between the SS blocks and the paging transmission / reception timing, thereby facilitating paging control in the gNB.

[0576] The UE may acquire information regarding paging reception timing. The acquisition of the information may be performed after rearranging the SS blocks. The information regarding paging reception timing may be, for example, a control channel resource set (CORESET) including paging information.

[0577] As another example, the gNB may fix the timing of paging transmission in the beam, which, for example, fixes the timing of paging reception in the UE, thereby reducing the amount of processing related to paging in the UE.

[0578] The timing of PRACH transmission from the UE in the beam associated with rearrangement of SS blocks may also be the same as the timing of paging transmission and reception.

[0579] As another example of the priority order between LTE non-MBSFN subframe signals and NR SS burst signals, NR SS burst signals may be prioritized over LTE non-MBSFN subframe signals. This, for example, can reduce interference experienced by NR SS bursts. The eNB may not transmit all or some of the LTE non-MBSFN subframe signals in subframes that overlap with NR SS bursts. The overlapping subframes mentioned above may instead be overlapping slots or overlapping minislots. As another example, the eNB may not transmit only the LTE non-MBSFN subframe signals that overlap with NR SS burst signals. This can prevent unnecessary outages of LTE non-MBSFN subframes.

[0580] The eNB may transmit a signal in an LTE non-MBSFN subframe that overlaps with a signal in an NR SS burst. These two signals may be separable from each other, for example, one of the signals may have a predetermined pattern. The separable signals may be similar to the case where the signal in an LTE non-MBSFN subframe is prioritized. This allows, for example, a UE to receive both LTE and NR signals.

[0581] The eNB may change the timing of paging transmission to the UEs under its control. The change may, for example, aggregate the timing of paging transmission to the UEs under its control into one or more timings. This reduces the overlap between the NR SS burst signal and the LTE paging transmission timing, eliminating the need for the eNB to stop paging transmission and reducing interference with the NR SS burst signal.

[0582] As an example of changing the paging transmission timing, the POs of the UEs under its control may be aggregated into one value. This makes it possible to avoid, for example, overlap between NR SS burst transmission and LTE paging transmission timing. As an example of a method of aggregating the POs into one value, the value of parameter Ns, which indicates the number of subframes to which paging signals are allocated in one radio frame, may be set to 1, as described in Non-Patent Document 17 (3GPP TS 36.304 V14.4.0). The eNB may set the value of parameter nB described in Non-Patent Document 17 (3GPP TS 36.304 V14.4.0) to 1 or less times T, thereby setting the value of parameter Ns to 1. The eNB may broadcast the changed value of parameter nB to the UEs under its control. For example, SIB2 may be used for the above-mentioned broadcast (see Non-Patent Document 18 (3GPP TS 36.311)). This allows, for example, the eNB to aggregate the POs of the UEs under its control into one way with a small amount of signaling.

[0583] The above-mentioned change in paging transmission timing may be, for example, a change in paging frame (PF), a change in paging occasion (PO), a change in paging transmission cycle, or a combination of two or more of the above.

[0584] When changing the paging transmission timing, the eNB may change a parameter used to determine the paging transmission timing. The parameter may be, for example, a UE-ID. The eNB may notify the UE of information related to the parameter change.

[0585] The eNB may notify the information to neighboring eNBs. The neighboring eNBs may be, for example, multiple eNBs that belong to the same tracking area as the eNB. The multiple eNBs may use the information to page the UE. This allows for smooth paging operations when, for example, mobility occurs in the UE.

[0586] The eNB may notify the information to a higher-level network device. The notification may be made using an interface between the higher-level network device and the base station. The higher-level network device may be an AMF or an SMF. The higher-level network device may transmit a notification to the eNB indicating whether to accept or reject the parameter change.

[0587] The upper network device may notify the information to a subordinate eNB. The subordinate eNB may be, for example, a plurality of eNBs that belong to the same tracking area as the eNB. The plurality of eNBs may use the information to page the UE. This allows smooth paging operations when, for example, mobility occurs in the UE.

[0588] The eNB may acquire information about the NR SS burst. The following (1) to (4) are disclosed as information about the NR SS burst.

[0589] (1) NR frame timing.

[0590] (2) Information about NR's SS.

[0591] (3) Information about NR communication methods.

[0592] (4) A combination of (1) to (3) above.

[0593] The eNB may acquire the NR frame timing described in (1) above using the cell search described in the first embodiment. The cell search may acquire the NR P-SS and S-SS. The eNB may have a function for performing the cell search. The eNB may set the timing for performing the cell search. As another example, the eNB may request information regarding the difference between the frame timing of LTE and NR from the gNB. The gNB may notify the eNB of the information. The request and / or the notification may be made via an inter-base station interface, for example, an Xn interface. The gNB may acquire the LTE frame timing. For example, the gNB may acquire the LTE frame timing using the cell search. This enables the eNB to acquire information regarding the NR SS burst, for example.

[0594] The eNB may request the information in (2) above from the gNB. The gNB may notify the eNB of the information in (2) above. The request and / or notification may be made using an inter-base station interface, for example, an Xn interface. The information in (2) above may be, for example, information about the code sequence and cyclic shift of the NR PSS, or information about the code sequence and cyclic shift of the NR SSS. The information in (2) above may include information about the duration of the NR SS burst. The information in (2) above may include information about the period of the NR SS burst. The eNB may perform a cell search using the information in (2) above. This, for example, enables the eNB to quickly perform the cell search process. Furthermore, for example, it becomes possible to prevent erroneous detection of an NR cell in the eNB.

[0595] As another example, the eNB may obtain the information (2) above using cell search, which may reduce the amount of signaling between base stations, for example.

[0596] The information in (3) above may include information about the NR multiplexing method (e.g., TDM, FDM) or information about the cyclic prefix (e.g., the length of the cyclic prefix duration). The information in (3) above may include information about the NR symbol length. The eNB may request the information in (3) from the gNB. The gNB may notify the eNB of the information. The request and / or notification may be made via an inter-base station interface, for example, an Xn interface. The eNB may use the information to derive the signal position of the NR SS burst. This allows, for example, the eNB to quickly obtain information about the NR SS burst.

[0597] As another example of the above (3), the eNB may obtain the information of the above (3) from NR broadcast information. This makes it possible to reduce the amount of signaling between base stations, for example.

[0598] Another solution is disclosed. An LTE non-MBSFN subframe signal and an NR SS burst signal may be transmitted simultaneously. These two signals may be separable from each other, for example, one of the signals may have a predetermined pattern. Separable signals may be, for example, a combination of an LTE SS and an NR PBCH, a combination of an LTE PBCH and an NR SS, or a combination of an LTE paging signal and an NR SS. A UE may receive the overlapping signals and separate each signal. For example, the UE may extract a signal with a predetermined pattern and obtain the difference between the original received signal and the extracted signal as the other signal. This allows the UE to receive both LTE and NR signals, for example.

[0599] Another solution is disclosed. An offset may be set at the frame boundary between LTE and NR. The offset may be in units of subframes, slots, or symbols. The offset may be in units smaller than a symbol, for example, in units of the minimum time (e.g., Ts) in the system.

[0600] The gNB and eNB may transmit NR SS burst signals that overlap with LTE non-MBSFN subframe signals. In this transmission, they may transmit signals that can be separated from each other, as disclosed in the above-mentioned solutions. This allows, for example, the LTE non-MBSFN subframe signals and the NR SS burst signals to coexist.

[0601] Figure 37 is a diagram showing an example in which an offset is provided to the LTE and NR frame boundaries. The example in Figure 37 shows a case in which the NR frame boundary is one symbol later than LTE. The example in Figure 37 shows a case in which the symbol lengths of LTE and NR are the same and the number of SS blocks in an NR SS burst is 8.

[0602] In Figure 37, because the NR frame boundary is delayed by one symbol compared to LTE, the first PBCH 4710 in NR subframe #0 overlaps with LTE SS 4701. Also, the second SS 4711 in NR subframe #0 overlaps with LTE PBCH 4702. Because the aforementioned PBCH 4710 and SS 4701 can be separated from each other, the gNB may transmit PBCH 4710. The same applies to NR SS 4711.

[0603] In the example of Figure 37, simultaneous transmission of the LTE SS and the PBCH of the first SS block of NR allows the coexistence of LTE non-MBSFN subframes and NR SS bursts, which, for example, allows UE synchronization acquisition to be performed quickly in NR.

[0604] The gNB may change the NR frame timing. The gNB may notify or broadcast the change to its subordinate UEs. The gNB may notify an upper network device of the frame timing change. The notification may use an interface between the upper network device and the base station. The upper network device may be an AMF or an SMF. The upper network device may send a notification to the gNB to accept or reject the frame timing change. The upper network device may instruct a subordinate gNB to change the frame timing. The target of the instruction may be a gNB nearby the gNB. This makes it possible, for example, to align the NR frame timing between neighboring gNBs including the gNB.

[0605] The eNB may change the LTE frame timing in a manner similar to the above-described method for changing the NR frame timing by the gNB.

[0606] Information about a change in NR and / or LTE frame timing may be included in system information, for example. Information about the change may be included in minimum SI. Information about the change may be broadcast to subordinate UEs or notified as Remaining Minimum System Information (RMSI). Alternatively, information about the change may be broadcast to subordinate UEs as Other SI or notified individually.

[0607] A carrier other than an NR carrier coexisting with LTE may be used to broadcast or notify information about the change. This allows, for example, a UE to quickly grasp the information. Alternatively, an NR carrier coexisting with LTE may be used to broadcast or notify information about the change. This eliminates the need for other multiple NR carriers to broadcast or notify information about the change, thereby reducing the amount of signaling.

[0608] For example, the eNB may broadcast or notify information about the change. The eNB may use the same method for broadcasting or notifying information about the change as the gNB. This allows the UE to quickly grasp information about the change.

[0609] Alternatively, neither the gNB nor the eNB may notify information about the change. The UE may automatically follow the LTE and / or NR frame timing change, which can reduce the amount of signaling.

[0610] Another solution is disclosed. The arrangement of SS blocks in an NR SS burst may be changed. For example, an NR SS block signal may be arranged in a minislot. One SS block may be arranged in different minislots. For example, two of the four symbols in one SS block may be arranged in one minislot, and the remaining two symbols may be arranged in the next minislot. The changed arrangement may be, for example, an arrangement that avoids the LTE CRS. This makes it possible to prevent, for example, mutual interference between the NR SS block and the LTE CRS.

[0611] The arrangement of SS blocks in NR SS bursts may have multiple patterns determined in advance by a standard. Multiple patterns may be determined for one symbol length. The UE may use the pattern information to perform SS block synchronization acquisition. This allows the UE to automatically acquire SS blocks in multiple SS block arrangement patterns.

[0612] The gNB may notify the UE of information regarding the change in the allocation of NR SS blocks. This information may be, for example, information indicating which of the above-mentioned SS block allocation patterns is being used. This allows the UE to continue capturing NR SS blocks even after the NR SS block allocation has been changed.

[0613] The information may be included in, for example, system information. The information may be included in minimum SI. The information may be broadcast to subordinate UEs or notified as Remaining Minimum System Information (RMSI). Alternatively, the information may be broadcast to subordinate UEs as Other SI or notified individually.

[0614] A carrier different from the NR carrier where the SS block allocation change occurs may be used to broadcast or notify the information. This allows, for example, a UE to quickly grasp the information. Alternatively, the NR carrier where the SS block allocation change occurs may be used to broadcast or notify the information. This, for example, eliminates the need for multiple other NR carriers to broadcast or notify information regarding the SS block allocation change, thereby reducing the amount of signaling.

[0615] For example, the eNB may broadcast or notify the information. The eNB may use the same method for broadcasting or notifying the information as the gNB. This allows the UE to quickly grasp the information, for example.

[0616] Alternatively, neither the gNB nor the eNB may notify the information. The UE may automatically reacquire the SS block after the NR allocation change. This can reduce the amount of signaling.

[0617] The solutions disclosed in the fourth embodiment may be combined with each other. For example, simultaneous transmission of LTE non-MBSFN subframe signals and NR SS burst signals may be enabled, and an offset may be provided at the LTE and NR frame boundary. This allows, for example, LTE non-MBSFN subframe signals and NR SS burst signals to coexist. Furthermore, even when different symbol lengths are used in LTE and NR, LTE non-MBSFN subframe signals and NR SS burst signals can coexist.

[0618] Figure 38 is a diagram showing an example of rearrangement of NR SS burst signals. Figure 38 shows an example of arrangement in which four symbols of an SS block are divided into two symbols. Figure 38 also shows an example in which NR SS is arranged in the first two symbols and NR PBCH is arranged in the last two symbols. In Figure 38, the SS block indicated by vertical stripes represents the SS, and the SS block indicated by horizontal stripes represents the PBCH.

[0619] In FIG. 38, NR SS4810 and PBCH4811 are arranged to avoid LTE CRS4800, SS4801, PBCH4802, and paging signal 4805. NR SS4820 is arranged to avoid CRS4800 in an area overlapping with LTE PBCH4802. NR PBCH4821 is arranged to overlap with LTE SS4801. LTE SS4801 and NR PBCH4821 shown in FIG. 38 may be mutually separable signals. LTE PBCH4802 and NR SS4820 shown in FIG. 38 may also be mutually separable signals.

[0620] The arrangement shown in Figure 38 allows NR SS block signals to avoid CRS and be separated from LTE SS and PBCH, thereby enabling coexistence of NR SS block signals and LTE non-MBSFN subframe signals.

[0621] According to the fourth embodiment, in the case of LTE-NR coexistence, the LTE non-MBSFN subframe signal and the NR SS burst signal can coexist, and it becomes possible to achieve both communication using LTE and communication using NR. As a result, the utilization efficiency of the communication system is improved.

[0622] Variation 1 of embodiment 4 In LTE-NR coexistence, preemption communication may be applied. The preemption communication may be either uplink or downlink. For example, in uplink preemption, while a UE is transmitting uplink data to an eNB, the UE may interrupt the uplink communication to a gNB. As another example, in downlink preemption, while an eNB is transmitting downlink data to the UE, the gNB may interrupt the UE with downlink transmission. Although the above description shows an example in which a gNB transmits and receives preemption data to and from a UE, the eNB may also transmit and receive preemption data to and from a UE.

[0623] The preemption communication in LTE-NR coexistence may be, for example, uplink preemption communication in uplink LTE-NR coexistence where the eNB and gNB use the same frequency band for uplink communication from the UE. Alternatively, the preemption communication in LTE-NR coexistence may be, for example, downlink preemption communication in downlink LTE-NR coexistence where the eNB and gNB use the same frequency band for downlink communication to the UE.

[0624] The following problem occurs when applying the above-mentioned method: No method for preemption communication in LTE-NR coexistence is disclosed. As a result, appropriate procedures for preemption communication cannot be implemented in LTE-NR coexistence, and low-latency, highly reliable communication cannot be ensured.

[0625] Solutions to the aforementioned problems are disclosed below.

[0626] The UE performs uplink preemption transmission to the base station performing the preemption communication (hereinafter, sometimes referred to as the preempting base station). The preempting base station may notify the base station interrupted by the preemption communication (hereinafter, sometimes referred to as the preempted base station) of information indicating that preemption has occurred. This allows, for example, the preempted base station to perform decoding processing by excluding received data at the timing corresponding to the preemption communication, thereby improving the reliability of communication between the preempted base station and the UE.

[0627] The aforementioned information indicating that preemption has occurred may include information about the resource on which the preemption occurred. The information may be information about timing, such as a subframe number, a slot number, a minislot number, or a symbol number. The information may include information about the number of minislots or the number of symbols. The information may include information about frequency, such as information about the frequency resource used in the preemption transmission. The information may include, for example, information about power. The preempted base station may use the information about power to separate the preempted communication from the interrupted communication. This separation may be used, for example, when the power of the preempted communication and the interrupted communication are significantly different. This allows the preempted base station to receive both the preempted communication and the interrupted communication.

[0628] The preemption base station may notify the UE that is performing LTE-NR coexistence of an uplink grant. The notification may be performed, for example, while the UE is receiving a downlink signal from the preemption base station. This eliminates the need for the UE to switch between LTE and NR downlink receiving circuits upon receiving the uplink grant, thereby reducing delays in uplink preemption transmission.

[0629] Alternatively, the preempting base station may notify the preempted base station of information about an uplink grant for the UE. The preempted base station may use the information about the uplink grant to stop receiving uplink data from the UE. This may provide, for example, the same effect as described above.

[0630] As another method, the preempting base station may notify the UE of information about the uplink grant for the UE via the preempted base station. The notification via the preempted base station may be made, for example, while the UE is receiving a downlink signal from the preempted base station. The uplink grant may include information indicating that the uplink transmission destination is the preempting base station. The information may be, for example, an identifier indicating whether the base station is a master or secondary base station, a base station ID, or a destination cell ID. The notification from the preempting base station to the preempted base station may be made using an inter-base station interface (e.g., an Xn interface). The preempted base station may stop uplink reception from the UE using the information about the uplink grant. The preempted base station notifies the UE of the information about the uplink grant. This eliminates the need for the UE to switch between LTE and NR downlink receiving circuits upon receiving the uplink grant, thereby reducing delays in uplink preemption transmission.

[0631] In the above, the preempted base station may stop uplink reception from the UE at the timing of occurrence of preemption transmission indicated in the uplink grant.

[0632] The UE may transmit an SR for the preempting base station to the preempting base station via the preempted base station. The SR may include information indicating that the scheduling request destination is the preempting base station. The information may be, for example, an identifier indicating whether the base station is a master or secondary base station, a base station ID, or a destination cell ID. The preempted base station may notify the preempting base station of information indicating that it has received the SR for the preempting base station. The notification from the preempted base station to the preempting base station may use an inter-base station interface (e.g., an Xn interface). This eliminates the need for the UE to switch between LTE and NR uplink transmission circuits in response to SR transmission, thereby reducing delays in uplink preemption transmission.

[0633] As another example of including information indicating that the scheduling request destination is a preempting base station in the SR transmitted from the UE to the preempted base station, the SR sequence may be made different depending on the scheduling request destination. For example, the sequence may have a different root index, a different cyclic shift amount, or both different values. The preempted base station may use the SR sequence to determine the scheduling request destination. This, for example, makes it possible to reduce the amount of information in the SR.

[0634] As another example, the sequence of the DMRS associated with the PUCCH including the SR may be different depending on the scheduling request destination. The preempted base station may use the sequence of the DMRS to determine the scheduling request destination. This makes it possible to reduce the amount of information in the SR, as described above.

[0635] The preempting base station may configure the SR to be transmitted to the base station itself for the UE. This configuration may be performed directly from the preempting base station to the UE or via the preempted base station.

[0636] The preempted base station may configure the UE with an SR to be transmitted to the preempting base station via the preempted base station. The SR configuration may include, for example, a configuration related to the SR transmission period and offset, a configuration related to the maximum number of SR retransmissions, or a configuration related to the SR frequency resource. The SR configuration may include a configuration related to a sequence used for transmitting the SR. The sequence-related configuration may be, for example, a configuration related to a root index or a configuration related to a cyclic shift. The SR configuration may include information related to the sequence of a DMRS associated with a PUCCH including the SR.

[0637] The setting regarding the SR that the UE transmits to the preempting base station and the setting regarding the SR that the UE transmits to the preempting base station via the preempted base station may be different from each other, or may be the same in part.

[0638] The setting of the SR that the UE transmits to the preempting base station via the preempted base station may be at least partially different from the setting of the SR that the UE transmits to the preempted base station. For example, the cyclic shift of the sequence used to transmit the SR may be made different. As another example, the sequences used for the DMRS associated with the PUCCH including the SR may be made different. This allows, for example, the preempted base station to distinguish between an SR for its own base station and an SR for the preempting base station via its own base station. As a result, it is possible to prevent malfunctions in the preempted base station.

[0639] The preempting base station may request the preempted base station to configure an SR that the UE transmits to the preempted base station via the preempted base station. The request may include, for example, information regarding the configuration of the SR. The preempted base station may use the information to configure the SR for the UE.

[0640] The request for configuration execution may be included in signaling in an inter-base station interface (e.g., an Xn interface). The signaling may be, for example, a secondary base station modification request (SN Modification Request), a secondary base station addition request (SN Addition Request), or a secondary base station modification confirm (SN Modification Confirm). The above three signalings may be used, for example, when the preemption base station is the master base station. As another example, the signaling may be a secondary base station modification request acknowledgement (SN Modification Request Acknowledge), a secondary base station addition request acknowledgement (SN Addition Request Acknowledge), or a notification indicating that a secondary base station modification request is present (SN Modification Required). The above three signalings may be used, for example, when the preemption base station is the secondary base station. The signaling may be other signaling, or new signaling may be provided.

[0641] The preempting base station may configure the SR to be transmitted to the UE via the preempted base station. The information included in the SR configuration may be the same as described above. The preempting base station may request information regarding the SR configuration to be transmitted to the UE via the preempted base station from the preempted base station. The preempted base station may notify the preempting base station of the information. The information may be the same as the SR configuration described above. As another example, the information may include information regarding the SR already assigned by the preempted base station. The SR configuration transmitted from the preempting base station to the UE may use the information notified by the preempted base station. This makes it possible to prevent, for example, the SR configuration from overlapping with the SR configuration already assigned by the preempted base station. As a result, it is possible to reduce interference in the preempted base station and prevent malfunctions.

[0642] RRC signaling may be used in the SR configuration transmitted from the preempting base station to the UE via the preempted base station. For example, information regarding the SR configuration may be included in the signaling of the RRC connection reconfiguration from the preempting base station to the UE. This may reduce the amount of signaling from the preempting base station to the UE. As another example, MAC signaling or L1 / L2 signaling may be used. This may enable the preempting base station to quickly configure the SR for the UE.

[0643] The preempting base station may request, from the preempted base station to the base station that information on the SR setting to be transmitted to the base station via the preempted base station, signaling of an interface between base stations, for example, an Xn interface, may be used. The signaling may be the same as the signaling of the request for SR setting execution transmitted from the preempting base station to the preempted base station by the UE via the preempted base station.

[0644] When the preempted base station notifies the preempting base station of information related to the SR configuration, signaling of an interface between base stations, for example, an Xn interface, may be used. The signaling may be, for example, a secondary base station modification request acknowledgement (SN Modification Request Acknowledge), a secondary base station addition request acknowledgement (SN Addition Request Acknowledge), or a notification indicating that a secondary base station modification request is present (SN Modification Required). The above three signalings may be used, for example, when the preempting base station is the master base station. As another example, a secondary base station modification confirmation (SN Modification Confirm) may be used. This signaling may be used, for example, when the preempting base station is a secondary base station. This signaling may be another signaling, or new signaling may be provided.

[0645] A combination of the above-mentioned SR settings may be used. For example, the preempting base station may configure the UE with both an SR to be transmitted directly to its own base station and an SR to be transmitted via the preempted base station. The settings may be performed using the same signaling or different signaling. As another example, the preempting base station may configure the UE with an SR to be transmitted directly to its own base station, and the preempted base station may configure the UE with an SR to be transmitted via its own base station to the preempting base station.

[0646] The UE may transmit an SR to either the preempting base station or the preempted base station. The transmission may be performed, for example, to the base station that has an earlier transmission available timing in the UE. This enables, for example, quick SR transmission from the UE with a small amount of processing. As another example, the transmission may be performed to the base station that arrives at the preempting base station with the SR arriving at the preempting base station earlier. When transmitting the SR to the base station that arrives at the preempting base station with the SR arriving at the preempting base station earlier, for example, the latency of the interface between base stations may be used as a factor in the UE's decision. The latency may be notified to the UE in advance. This enables the preempting base station to receive the SR quickly.

[0647] The UE may transmit an SR to both the preempting base station and the preempted base station. This, for example, enables improvement of reliability in SR transmission. In the above description, for example, an SR retransmission prohibition timer may be provided separately for a direct SR transmission to the preempting base station and for an SR transmission via the preempted base station. This, for example, enables avoidance of complexity in SR control. As another example, the SR retransmission prohibition timer may be common to a direct SR transmission to the preempting base station and an SR transmission via the preempted base station. In the SR retransmission prohibition timer, the UE may be allowed to transmit an SR only once to a base station that is not the destination of the SR transmission that started the timer.

[0648] The above-mentioned SR configuration, for example, the configuration of the SR transmission timing, does not require the use of information regarding the allocation of uplink signal reception timings from the UE among the base stations. The UE does not require the transmission of an SR to the preempting base station and / or the preempted base station at the above-mentioned SR transmission timing. That is, the transmission of an SR from the UE to each base station may be performed when the uplink signal reception timing from the UE is assigned to the base station and at a timing corresponding to the above-mentioned SR transmission timing. For example, when the uplink signal reception timing from the UE is assigned to the preempting base station, the UE may not transmit the SR at the SR transmission timing to the preempted base station. This makes it possible to avoid the complexity of the SR configuration, for example, during LTE-NR coexistence.

[0649] As another example, in the above-mentioned SR configuration, information regarding the allocation of uplink signal reception timings from the UE among base stations may be used. For example, the above-mentioned SR transmission timing in the UE may be set from among the timings at which the uplink signal reception timings from the UE are assigned to the SR transmission destination base station. As another example, the above-mentioned SR transmission timing configuration in the UE may be used to set the uplink signal reception timing from the UE in the SR transmission destination base station. This, for example, means that the uplink signal reception timing from the UE is assigned to the SR transmission destination base station at the SR transmission timing, making it possible to quickly execute SR transmission from the UE, for example.

[0650] A plurality of SR settings may be provided to be transmitted from the UE to each base station. For example, in an SR from the UE to a preemption base station, both a setting of 5 millisecond period and subframe offset 0 and a setting of 5 millisecond period and subframe offset 2 may be used. This allows for improved flexibility in SR settings.

[0651] The above-mentioned setting for SR may be applied to the setting for other UCI. For example, the above-mentioned setting method for SR may be applied to the CSI setting. By doing so, for example, the same effect as that of the transmission of SR can be obtained for the transmission of other UCI.

[0652] Preemption may also be applied to the SR transmitted from the UE to the preempting base station. For example, the UE may suspend uplink transmission to the preempted base station and transmit the SR to the preempting base station. After transmitting the SR, the UE may or may not resume uplink transmission to the preempted base station. This allows, for example, the UE to quickly notify the SR.

[0653] In the above, the UE may transmit the SR using a configuration related to the SR to be transmitted to the preemption base station. That is, the UE may transmit the SR using information related to the SR transmission timing (e.g., an SR transmission period, an SR transmission offset) included in the configuration.

[0654] The preempted base station may not allocate uplink transmission from the UE to its own base station at the transmission timing of an SR transmitted from the UE to the preempting base station. The uplink transmission may be, for example, a PUSCH, a DMRS transmission, a PUCCH, an SRS, or another uplink signal. The preempted base station may notify the preempted base station of information regarding the setting of SR transmission from the UE to its own base station. The preempted base station may use the notification to determine or change the allocation of uplink transmission timing from the UE to its own base station.

[0655] As another example, the preempting base station may set the timing at which the UE may transmit an SR to its own base station to be different from the timing at which uplink transmission from the UE to the preempted base station occurs. The uplink transmission may be, for example, DMRS, SRS, or another uplink signal. The preempting base station may inquire of the preempted base station about information regarding the timing at which the uplink transmission occurs. The preempted base station may notify the preempting base station of the information. The preempting base station may use the notification to notify information regarding the setting of SR transmission from the UE to its own base station. The timing at which the UE may transmit an SR to its own base station may be set different from the timing at which uplink transmission from the UE to the preempted base station occurs.

[0656] The preempting base station may notify the preempted base station of information regarding the timing at which uplink preemption transmission may occur. This information may be the same as the information shown in the third embodiment, for example. The preempted base station may stop uplink reception from the UE at that timing. This makes it possible to reduce delays in uplink preemption transmission, for example.

[0657] The UE may notify the preemption base station of information indicating the occurrence of preemption transmission data. For example, a predetermined code may be used as the information. The code may be the same as that shown in Modification 1 of the third embodiment. The UE may notify the preemption base station of the information immediately after the occurrence of the preemption transmission data. This makes it possible to reduce delays in uplink preemption transmission, for example.

[0658] In the above, the UE may notify the preempting base station of the information via the preempted base station. The notification via the preempted base station may be made, for example, while the UE is transmitting an uplink signal to the preempted base station. The notification from the preempted base station to the preempting base station may use an inter-base station interface (for example, an Xn interface). This eliminates the need for the UE to switch between LTE and NR uplink transmission circuits in association with SR transmission, thereby reducing delays in uplink preemption transmission.

[0659] Another solution is disclosed. In downlink preemption communication, the preempting base station may notify the preempted base station of information indicating that a preemption transmission will occur. The information may include, for example, information regarding the timing at which the downlink preemption will occur, or information regarding the scheduling of the downlink preemption communication. The preempted base station may stop downlink transmission at the timing of the preemption transmission. This makes it possible to reduce interference in downlink preemption communication.

[0660] The preempted base station may notify the UE of information indicating that a preemption transmission will occur. This notification may be made before or after the preempting base station notifies the preempted base station. The UE may use this notification to switch between LTE and NR downlink receiving circuits. This may reduce delays in downlink preemption communications, for example.

[0661] In the notification to the UE, for example, a predetermined code may be used. The code may be the same as that shown in Variation 1 of the third embodiment. The UE may receive the code and switch between LTE and NR downlink receiving circuits. This may further reduce delays in downlink preemption communication, for example.

[0662] The preempting base station may inquire in advance of the preempted base station about the timing at which preemption is possible or impossible.

[0663] The preempted base station may notify the preempting base station in advance of information regarding the timing at which preemption communication is possible. The notification may be made, for example, after the aforementioned inquiry, or may be made when there is no such inquiry. The information may be information regarding the timing at which preemption communication is impossible. The timing at which preemption communication is impossible may be, for example, the timing at which the preempted base station transmits a synchronization signal, the timing at which it transmits broadcast information, or the timing at which it transmits a PDCCH. The preempting base station may or may not perform preemption communication using the information. For example, the preempting base station may perform preemption transmission at a timing at which preemption is possible.

[0664] The information regarding timings during which preemption is possible or impossible may include, for example, information regarding subframes during which preemption is possible or impossible, information regarding the period at which the subframes are repeated, or information regarding the duration of timings during which preemption is possible or impossible. Non-preemptable subframes may be, for example, subframes in which SS (synchronization signal) bursts are transmitted in NR, or other subframes. In the above, a subframe may be a radio frame, a slot, a minislot, or a symbol. The information may be a combination of multiple pieces of information. As another example, the information may be notified as a bitmap indicating symbols during which preemption is possible or impossible. The symbols may be subframes, slots, minislots, or other time units. The information may be notified periodically or aperiodically. The information may include information regarding the period covered by the information. This, for example, enables greater flexibility in setting timings during which preemption is possible or impossible.

[0665] Another solution is disclosed. In downlink preemption communication, the preempting base station may notify the UE of information indicating that a preemption transmission has occurred. The information may include, for example, information regarding the timing at which the downlink preemption occurred or information regarding the scheduling of the downlink preemption communication. The notification to the UE may be sent via the preempted base station. The UE may use the notification to extract preemption communication data from the received downlink signal. For example, an extraction method may be a method of correcting the offset of the DC component between LTE and NR. This may reduce the amount of signaling between the base station and the UE before the preemption communication.

[0666] The solutions disclosed in this first modification may be combined with each other. For example, the preempting base station may notify the preempted base station of information indicating tha...

Claims

1. A user device; A plurality of base stations each in wireless communication with the user equipment; A communication system comprising: The plurality of base stations include a master base station and a secondary base station that configure dual connectivity for the user equipment; the master base station is configured to set a first grant configuration for uplink grant-free transmission to the master base station for each of one or more cells formed by the master base station; The secondary base station is configured to set a second grant configuration related to uplink grant-less transmission to the secondary base station for each of one or more cells formed by the secondary base station; The user equipment receives, from the master base station, configuration information in which the first grant configuration and the second grant configuration are set independently of each other. Communication systems.

2. the grant-less transmission based on the second grant configuration is an uplink transmission that does not require a grant provided from the secondary base station based on a request by the user equipment, The grant-free transmission based on the first grant configuration is an uplink transmission that does not require a grant provided from the master base station based on a request by the user equipment. The communication system according to claim 1 .

3. the secondary base station notifies the master base station of the second grant configuration; The master base station notifies the user equipment of the notified second grant configuration. The communication system according to claim 1 .

4. The secondary base station notifies the user equipment of an L1 configuration that specifies a configuration of the second grant configuration. The communication system according to claim 1 .

5. The secondary base station notifies the user equipment of a part or all of an RRC configuration corresponding to the second grant configuration; The communication system according to claim 1 .

6. The secondary base station notifies the master base station of information indicating a change in the second grant configuration; The master base station notifies the user equipment of the information notified from the secondary base station. The communication system according to claim 1 .

7. The secondary base station notifies the master base station of information indicating release of the grant-less transmission based on the second grant configuration; The master base station notifies the user equipment of the information notified from the secondary base station. The communication system according to claim 1 .

8. The master base station sets the first grant configuration in packet duplication. The communication system according to claim 1 .

9. The user equipment measures a quality of service (QoS) value and a delay time of uplink packet data; The communication system according to claim 1 .

10. The secondary base station applies the second grant configuration to an SCG bearer or a split bearer corresponding to the secondary base station; The communication system according to claim 1 .

11. At least one of the base stations sets a grant configuration for uplink transmission without grant in carrier aggregation; The communication system according to claim 1 .

12. In the carrier aggregation in which the grant configuration is set, packet duplication is further set.

12. The communication system of claim 11.

13. The secondary base station sets the second grant configuration in packet duplication. The communication system according to claim 1 .

14. In the radio resource in which the grant-less transmission is configured, the user equipment performs uplink transmission according to a priority order based on information notified by RRC signaling. The communication system according to claim 1 .

15. The priority order followed by the user equipment is a priority order according to a channel.

15. The communication system of claim 14.

16. A user equipment in a communication system including a plurality of base stations each of which wirelessly communicates with the user equipment, The plurality of base stations include a master base station and a secondary base station that configure dual connectivity for the user equipment; the master base station is configured to set a first grant configuration for uplink grant-free transmission to the master base station for each of one or more cells formed by the master base station; The secondary base station is configured to set a second grant configuration related to uplink grant-less transmission to the secondary base station for each of one or more cells formed by the secondary base station; The user equipment receives, from the master base station, configuration information in which the first grant configuration and the second grant configuration are set independently of each other. User equipment.

17. A master base station in a communication system including a user device and a plurality of base stations each of which wirelessly communicates with the user device, The plurality of base stations include the master base station and a secondary base station that configure dual connectivity for the user equipment, the master base station is configured to set a first grant configuration for uplink grant-free transmission to the master base station for each of one or more cells formed by the master base station; The secondary base station is configured to set a second grant configuration related to uplink grant-less transmission to the secondary base station for each of one or more cells formed by the secondary base station; The master base station is configured to transmit, to the user equipment, configuration information in which the first grant configuration and the second grant configuration are set independently of each other. Master base station.

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