Communication system, base station and user equipment

Abstract

When a cell is spatially separated by multiple wireless beams, it can simplify radio resource management. A cell (811) formed by a base station device (800) is spatially separated by multiple wireless beams (804 to 810) subordinate to the base station device (800). The base station device (800) shares RRC (Radio Resource Control) parameters used by communication terminal devices in two or more of the multiple wireless beams (804 to 810).

Description

[0001] This application is a divisional application of a patent application for invention titled "Communication System", with an international filing date of December 28, 2017, and an application number of 201780079241.1 (international application number PCT / JP2017 / 047155). Technical Field

[0002] The present invention relates to a communication system that performs wireless communication between communication terminal devices such as mobile terminal devices and base station devices. Background Art

[0003] In 3GPP (3rd Generation Partnership Project), a standardization organization for mobile communication systems, a communication method called Long Term Evolution (LTE) in the radio section and System Architecture Evolution (SAE) in the overall system structure including the core network and radio access network (hereinafter also collectively referred to as the network) has been studied (for example, Non-Patent Documents 1 to 5). This communication method is also called a 3.9G (3.9th generation) system.

[0004] As an access method for LTE, OFDM (Orthogonal Frequency Division Multiplexing) is used in the downlink direction, and SC-FDMA (Single Carrier Frequency Division Multiple Access) is used in the uplink direction. In addition, unlike W-CDMA (Wideband Code division Multiple Access), LTE does not include circuit switching and is only a packet communication method.

[0005] Use Figure 1 Describe the decisions regarding the frame structure of the LTE system in 3GPP described in Non-Patent Document 1 (Chapter 5). Figure 1 It is an explanatory diagram showing the structure of a radio frame used in a communication system of the LTE method. Figure 1In this case, a radio frame is 10 ms. The radio frame is divided into 10 subframes of equal size. The subframe is divided into 2 time slots of equal size. The first and sixth subframes of each radio frame contain downlink synchronization signals. The synchronization signal has a primary synchronization signal (P-SS) and a secondary synchronization signal (S-SS).

[0006] Non-patent Document 1 (Chapter 5) describes the decisions related to the channel structure in the LTE system in 3GPP. It is assumed that the same channel structure as that of non-CSG cells is also used in CSG (Closed Subscriber Group) cells.

[0007] The physical broadcast channel (PBCH) is a downlink transmission channel from a base station device (hereinafter sometimes simply referred to as "base station") to a communication terminal device such as a mobile terminal device (hereinafter sometimes simply referred to as "mobile terminal") (hereinafter sometimes simply referred to as "communication terminal"). The BCH transport block is mapped to four subframes at 40 ms intervals. There is no clear signaling for the 40 ms timing.

[0008] The physical control format indicator channel (PCFICH) is a downlink transmission channel from a base station to a communication terminal. The PCFICH notifies a communication terminal from a base station of the number of OFDM (Orthogonal Frequency Division Multiplexing) symbols for PDCCHs. The PCFICH is transmitted for each subframe.

[0009] The Physical Downlink Control Channel (PDCCH) is a downlink transmission channel from the base station to the communication terminal. The PDCCH notifies the resource allocation information of the Downlink Shared Channel (DL-SCH), which is one of the transmission channels described later, the resource allocation information of the Paging Channel (PCH), which is one of the transmission channels described later, and the Hybrid Automatic Repeat reQuest (HARQ) information related to the DL-SCH. The PDCCH transmits the Uplink Scheduling Grant. The PDCCH transmits the Ack (Acknowledgement) / Nack (Negative Acknowledgement), which is a response signal for uplink transmission. The PDCCH is also referred to as the L1 / L2 control signal.

[0010] The Physical Downlink Shared Channel (PDSCH) is a downlink transmission channel from the base station to the communication terminal. The Downlink Shared Channel (DL-SCH) as a transmission channel and the PCH as a transmission channel are mapped to the PDSCH.

[0011] The Physical Multicast Channel (PMCH) is a downlink transmission channel from the base station to the communication terminal. The Multicast Channel (MCH) as a transmission channel is mapped to the PMCH.

[0012] The Physical Uplink Control Channel (PUCCH) is an uplink transmission channel from the communication terminal to the base station. The PUCCH transmits the ACK / Nack, which is a response signal for downlink transmission. The PUCCH transmits the CQI (Channel Quality Indicator) report. The CQI is quality information indicating the quality of the received data or the communication line quality. The PUCCH also transmits the Scheduling Request (SR).

[0013] The Physical Uplink Shared Channel (PUSCH) is an uplink transmission channel from a communication terminal to a base station. The PUSCH is mapped with the Uplink Shared Channel (UL-SCH), which is one of the transport channels.

[0014] The Physical Hybrid ARQ Indicator Channel (PHICH) is a downlink transmission channel from a base station to a communication terminal. The PHICH transmits the response signal, i.e., Ack / Nack, for the uplink transmission. The Physical Random Access Channel (PRACH) is an uplink transmission channel from a communication terminal to a base station. The PRACH transmits a random access preamble.

[0015] The downlink reference signal (Reference Signal: RS) is a symbol known in a communication system of the LTE system. The following five types of downlink reference signals are defined: Cell-specific Reference Signal (CRS), MBSFN reference signal, UE-specific Reference signal, i.e., Demodulation Reference Signal (DM-RS), Positioning Reference Signal (PRS), and Channel-State Information Reference Signal (CSI-RS). As a measurement of the physical layer of a communication terminal, there is a measurement of the Reference Signal Received Power (RSRP).

[0016] Describe the transport channel described in Non-Patent Document 1 (Chapter 5). Among the downlink transport channels, the Broadcast Channel (BCH) is broadcast over the entire coverage area of its base station (cell). The BCH is mapped to the Physical Broadcast Channel (PBCH).

[0017] Retransmission control using Hybrid ARQ (HARQ) is applied to the Downlink Shared Channel (DL-SCH). The DL-SCH can broadcast over the entire coverage area of a base station (cell). The DL-SCH supports dynamic or semi-static resource allocation. Semi-static resource allocation is also referred to as Persistent Scheduling. The DL-SCH supports Discontinuous Reception (DRX) of a communication terminal in order to reduce the power consumption of the communication terminal. The DL-SCH is mapped to the Physical Downlink Shared Channel (PDSCH).

[0018] The Paging Channel (PCH) supports DRX of a communication terminal in order to reduce the power consumption of the communication terminal. The PCH is required to broadcast over the entire coverage area of a base station (cell). The PCH is mapped to a physical resource such as the Physical Downlink Shared Channel (PDSCH) that can be dynamically used for traffic.

[0019] The Multicast Channel (MCH) is used to broadcast over the entire coverage area of a base station (cell). The MCH supports the SFN synthesis of the Multimedia Broadcast Multicast Service (MBMS) services (MTCH and MCCH) in multi-cell transmission. The MCH supports semi-static resource allocation. The MCH is mapped to the PMCH.

[0020] Retransmission control using Hybrid ARQ (HARQ) is applied to the Uplink Shared Channel (UL-SCH) in the uplink transmission channel. The UL-SCH supports dynamic or semi-static resource allocation. The UL-SCH is mapped to the Physical Uplink Shared Channel (PUSCH).

[0021] The Random Access Channel (RACH) is restricted by control information. There is a risk of collision in the RACH. The RACH is mapped to the Physical Random Access Channel (PRACH).

[0022] Describe Hybrid Automatic Repeat reQuest (HARQ). HARQ is a technology that improves the communication quality of a transmission line by combining Automatic Repeat reQuest (ARQ) and Forward Error Correction. HARQ has the following advantages: Even for a transmission line with changing communication quality, retransmission can be used to effectively utilize error correction. In particular, when retransmitting, the quality can be further improved by combining the reception results of the first transmission and the retransmission.

[0023] Describe an example of the retransmission method. When the receiving side cannot correctly decode the received data, in other words, when a Cyclic Redundancy Check (CRC) error occurs (CRC = NG), a "Nack" is sent from the receiving side to the transmitting side. The transmitting side that receives the "Nack" retransmits the data. When the receiving side can correctly decode the received data, in other words, when no CRC error occurs (CRC = OK), an "Ack" is sent from the receiving side to the transmitting side. The transmitting side that receives the "Ack" transmits the next data.

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

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

[0026] The Common Control Channel (CCCH) is a channel used for sending control information between a communication terminal and a base station. The CCCH is used in the following cases: that is, when there is no Radio Resource Control (RRC) connection between the communication terminal and the network. In the downlink direction, the CCCH is mapped to the Downlink Shared Channel (DL-SCH) as a transport channel. In the uplink direction, the CCCH is mapped to the Uplink Shared Channel (UL-SCH) as a transport channel.

[0027] The Multicast Control Channel (MCCH) is a downlink channel for point-to-multipoint transmission. The MCCH is used to send MBMS control information for one or several MTCHs from the network to the communication terminal. The MCCH is only used by the communication terminal during the MBMS reception process. The MCCH is mapped to the Multicast Channel (MCH) which is a transport channel.

[0028] The Dedicated Control Channel (DCCH) is a channel for sending dedicated control information between the communication terminal and the network in a point-to-point manner. The DCCH is used when the communication terminal has an RRC connection. In the uplink, the DCCH is mapped to the Uplink Shared Channel (UL-SCH), and in the downlink, it is mapped to the Downlink Shared Channel (DL-SCH).

[0029] The Dedicated Traffic Channel (DTCH) is a channel for sending user information and for point-to-point communication with an individual communication terminal. The DTCH exists in both the uplink and the downlink. In the uplink, the DTCH is mapped to the Uplink Shared Channel (UL-SCH), and in the downlink, it is mapped to the Downlink Shared Channel (DL-SCH).

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

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

[0032] A CSG (Closed Subscriber Group) cell is a cell for subscribers with specific usage rights by an operator (hereinafter sometimes referred to as a "cell for specific subscribers"). Specific subscribers are permitted to access one or more cells of a PLMN (Public Land Mobile Network). One or more cells permitted for specific subscribers to access are called "CSG cells (CSG cell(s))". However, there are access restrictions in the PLMN.

[0033] A CSG cell is part of a PLMN that broadcasts an inherent CSG identity (CSG ID) and broadcasts "TRUE" using a CSG Indication. Members of a subscriber group that have been pre-registered and permitted use the CSG ID in the access permission information to access the CSG cell.

[0034] The CSG ID is broadcast by a CSG cell or a cell. There are multiple CSG IDs in an LTE-based communication system. Also, for easy access by CSG associated members, the CSG ID is used by a communication terminal (UE).

[0035] Location tracking of a communication terminal is performed in units of an area composed of one or more cells. Location tracking is for tracking the location of the communication terminal even in the standby state so as to call the communication terminal, in other words, for being able to call the communication terminal. The area used for location tracking of this communication terminal is called a tracking area.

[0036] In 3GPP, base stations called Home-NodeB (Home-NB; HNB) and Home-eNodeB (Home-eNB; HeNB) have been studied. The HNB in UTRAN and the HeNB in E-UTRAN are, for example, base stations for access services for home, corporate, and commercial use. Three different access modes for the HeNB and HNB are disclosed in Non-Patent Document 2. Specifically, an Open access mode, a Closed access mode, and a Hybrid access mode are disclosed.

[0037] In addition, in 3GPP, as Release 10, the standardization of Long Term Evolution Advanced (LTE-A) is continuously evolving (see Non-Patent Documents 3 and 4). LTE-A is based on the radio access communication method of LTE and is constituted by adding some new technologies to it.

[0038] In the LTE-A system, in order to support a wider transmission bandwidth of up to 100 MHz, carrier aggregation (CA) that aggregates two or more component carriers (CCs) (also referred to as "aggregation") has been studied. CA is described in Non-Patent Document 1.

[0039] When CA is configured, the UE has a unique RRC connection with the network (NW). In the RRC connection, one serving cell provides NAS mobility information and security inputs. This cell is called the primary serving cell (PCell). In the downlink, the carrier corresponding to the PCell is the downlink primary component carrier (DLPCC). In the uplink, the carrier corresponding to the PCell is the uplink primary component carrier (ULPCC).

[0040] According to the UE's capability, secondary cells (SCs) are configured to form a serving cell group with the Pcell. In the downlink, the carrier corresponding to the SCell is the downlink secondary component carrier (DLSCC). In the uplink, the carrier corresponding to the SCell is the uplink secondary component carrier (ULSCC).

[0041] For one UE, a serving cell group formed by one PCell and one or more SCells is configured.

[0042] In addition, as new technologies of LTE-A, there are technologies such as wider bandwidth extension and coordinated multiple point transmission and reception (CoMP). CoMP studied for the implementation of LTE-A in 3GPP is described in Non-Patent Document 1.

[0043] In addition, in 3GPP, in order to cope with the huge future traffic volume, research is being conducted on the use of small eNBs (hereinafter sometimes referred to as "small-scale base station devices") that form small cell areas. For example, research is being conducted on technologies such as improving frequency utilization efficiency and increasing communication capacity by setting up multiple small eNBs and forming multiple small cell areas. Specifically, there is Dual Connectivity (DC) in which a UE is connected to two eNBs for communication. DC is described in Non-Patent Document 1.

[0044] Sometimes one of the eNBs performing Dual Connectivity (DC) is referred to as the "Master eNB (abbreviation: MeNB)", and the other is referred to as the "Secondary eNB (abbreviation: SeNB)".

[0045] The traffic volume of the mobile network has a tendency to increase, and the communication speed is also continuously developing towards high speed. If LTE and LTE-A are officially put into use, it can be foreseen that the communication speed will be further increased.

[0046] In addition, a fifth-generation (hereinafter sometimes referred to as "5G") radio access system aiming at starting services for the next-generation mobile communication after 2020 is under research. For example, in Europe, an organization called METIS is summarizing the requirements for 5G (refer to Non-Patent Document 5).

[0047] In the 5G radio access system, for the LTE system, the following necessary conditions for further power consumption reduction and device cost reduction are cited: the system capacity is 1000 times, the data transfer speed is 100 times, the data processing delay is 1 / 10, and the number of simultaneous connections of communication terminals is 100 times.

[0048] In order to meet the above requirements, in 3GPP, the standard research on 5G is being carried out as Release 14 (refer to Non-Patent Documents 6 to 10). The technology of the 5G radio section is called "New Radio (abbreviation: NR) Access Technology: new radio access technology", and several new technologies are being studied (refer to Non-Patent Documents 11 to 14). For example, research is being conducted on mobility without RRC, multi-beamforming (MBF) based on analog beamforming or hybrid beamforming, network slicing, etc.

[0049] Prior Art Documents

[0050] Non-Patent Documents

[0051] Non-Patent Document 1: 3GPP TS36.300 V14.0.0

[0052] Non-Patent Document 2: 3GPP S1-083461

[0053] Non-Patent Document 3: 3GPP TR36.814 V9.0.0

[0054] Non-Patent Document 4: 3GPP TR36.912 V13.0.0

[0055] Non-Patent Document 5: "Scenarios, requirements and KPIs for 5G mobile and wireless system", [online], April 30, 2013 (Heisei 25), ICT-317669-METIS / D1.1, [searched on December 8, 2016], Internet <https: / / www.metis2020.com / documents / deliverables / >

[0056] Non-Patent Document 6: 3GPP TR23.799 V1.1.0

[0057] Non-Patent Document 7: 3GPP TR38.801 V0.4.0

[0058] Non-Patent Document 8: 3GPP TR38.802 V1.0.0

[0059] Non-Patent Document 9: 3GPP TR38.804 V0.4.0

[0060] Non-Patent Document 10: 3GPP TR38.912 V0.0.2

[0061] Non-Patent Document 11: 3GPP R2-164670

[0062] Non-Patent Document 12: 3GPP TS36.331 V14.0.0

[0063] Non-Patent Document 13: 3GPP R1-165364

[0064] Non-Patent Document 14: 3GPP R2-165542 Summary of the Invention

[0065] Problems to be Solved by the Invention

[0066] In NR, mobility without RRC is studied. In NR that uses a higher frequency compared to LTE, by forming beams to concentrate power within a narrow range and using one or more beams to cover the required coverage area. Since beam movement frequently occurs along with the movement of the UE, mobility without RRC is utilized to reduce the signaling associated with beam-to-beam movement.

[0067] In communication using multiple beams or multiple TRPs (Transmission / Reception Points) in NR, the communicable space is separated by each beam or each TRP. However, how to handle RRC parameters in the above situation has not been disclosed. Therefore, even if the communicable space is separated within a cell, the number of UEs that can be accommodated within the cell does not increase.

[0068] When carrier aggregation (CA) that collects and uses multiple carriers as radio resources for communication is applied to NR, it is not clear which beam of the cell should be aggregated, so the gNB cannot set CA for the UE. Therefore, a lot of radio resources cannot be used, and high-speed and high-capacity communication services cannot be provided to the UE.

[0069] In addition, in LTE, in DC (Dual Connectivity) which is a technology used to provide high-speed and high-capacity communication services, a bearer setting of a secondary base station (Secondary eNB: SeNB) is requested from a master base station (Master eNB: MeNB). In this bearer setting request, E-RAB parameters are used. However, in 5G, since network slicing is used, control based on flows is discussed between the CN and the RAN, and control based on bearers is used in the RAN. As a result, since E-RAB disappears, the method of requesting bearer setting from the MgNB (Master gNB) to the SgNB (Secondary gNB) becomes unclear. Therefore, in 5G, DC cannot be used, and the usage efficiency of radio resources is greatly reduced.

[0070] An object of the present invention is to provide a communication system that increases the number of UEs accommodated in NR and enables high-speed and high-capacity communication in the UEs.

[0071] Technical solutions for solving technical problems

[0072] The first communication system of the present invention includes: a communication terminal device; and a base station device that performs wireless communication with the communication terminal device via a wireless beam. A cell constituted by the base station device is separated by a plurality of wireless beam spaces under the base station device, and the base station device shares RRC (Radio Resource Control) parameters used for the communication terminal among two or more of the plurality of wireless beams.

[0073] The second communication system of the present invention includes: a communication terminal device; and a base station device that performs wireless communication with the communication terminal device via a wireless beam. A cell formed by the base station device is spatially separated by a plurality of wireless beam spaces subordinate to the base station device. When the communication terminal device moves from the coverage area of a first wireless beam to the coverage area of a second wireless beam, the base station device changes the RRC (Radio Resource Control) parameters used for the communication terminal device from first RRC parameters for the first wireless beam to second RRC parameters for the second wireless beam.

[0074] The third communication system of the present invention includes: a communication terminal device; and a base station device that performs wireless communication with the communication terminal device via a wireless beam. A cell formed by the base station device is spatially separated by a plurality of wireless beam spaces subordinate to the base station device. The base station device sets carrier aggregation in units of wireless beams.

[0075] The fourth communication system of the present invention includes: a communication terminal device; a plurality of base station devices connected in a manner capable of wireless communication with the communication terminal device; and a core network that manages communication between the communication terminal device and each base station device. When a first base station device connected to the communication terminal device requests a second base station device to set a bearer for the communication terminal device, the first base station device notifies the second base station device of information related to QoS (Quality of Service) obtained from the core network for a PDU session. The second base station device sets the bearer for the communication terminal device based on the notified information related to QoS.

[0076] The fifth communication system of the present invention includes: a communication terminal device; a plurality of base station devices connected in a manner capable of wireless communication with the communication terminal device; and a core network that manages communication between the communication terminal device and each base station device. When a first base station device connected to the communication terminal device requests a second base station device to set a bearer for the communication terminal device, the first base station device sets the bearer for the communication terminal device based on the QoS (Quality of Service) obtained from the core network for a PDU session, and notifies the second base station device of information related to the set bearer.

[0077] Advantages of the Invention

[0078] According to the first communication system of the present invention, RRC parameters used for a communication terminal device are shared among two or more of a plurality of wireless beams that spatially separate a cell formed by a base station device. Therefore, radio resource management can be simplified.

[0079] According to the second communication system of the present invention, the RRC parameters used for the communication terminal device are changed according to the change of the wireless beam for the communication terminal device. Therefore, the accommodation number of the communication terminal device can be increased.

[0080] According to the third communication system of the present invention, carrier aggregation is set in units of wireless beams. Therefore, a cell supporting beamforming can be set as a cell for carrier aggregation, and the used radio resources can be increased. Thereby, a high-speed and large-capacity communication service can be provided.

[0081] According to the fourth communication system of the present invention, the first base station device notifies the second base station device of the QoS-related information obtained for the PDU session from the core network, and the second base station device sets a bearer for the communication terminal device based on the notified QoS-related information. Therefore, dual connectivity (DC) can be set for the fifth-generation (5G) radio access system.

[0082] According to the fifth communication system of the present invention, the first base station device sets a bearer for the communication terminal device based on the QoS (Quality of Service) obtained for the PDU session from the core network, and notifies the second base station device of the information related to the set bearer. Therefore, dual connectivity (DC) can be set for the fifth-generation (5G) radio access system.

[0083] The objectives, features, aspects, and advantages of the present invention will become more apparent through the following detailed description and the accompanying drawings. Description of the Drawings

[0084] Figure 1 It is an explanatory diagram showing the structure of a radio frame used in a communication system of the LTE method.

[0085] Figure 2 It is a block diagram showing the overall structure of a communication system 200 of the LTE method discussed in 3GPP.

[0086] Figure 3 It is a communication terminal related to the present invention, that is Figure 2 A block diagram showing the structure of the mobile terminal 202 shown.

[0087] Figure 4 It is a base station related to the present invention, that is Figure 2 A block diagram showing the structure of the base station 203 shown.

[0088] Figure 5 It is a block diagram showing the structure of the MME related to the present invention.

[0089] Figure 6It is a flowchart showing an overview of cell search by a communication terminal (UE) in a communication system using the LTE method until the standby operation.

[0090] Figure 7 It is a diagram showing the concept of a cell structure in the case where a macro eNB and a small eNB coexist.

[0091] Figure 8 It is a diagram showing the separation of a communicable space by multiple beams or TRPs in Embodiment 1.

[0092] Figure 9 It is a flowchart when performing beam / TRP switching using MAC signaling in Embodiment 2.

[0093] Figure 10 It is a flowchart when performing beam / TRP switching using MAC signaling in Embodiment 3.

[0094] Figure 11 It is a flowchart when performing beam / TRP switching using MAC signaling in Embodiment 4.

[0095] Figure 12 It is a diagram explaining the architecture of CA set in units of beams in a gNB in Embodiment 6.

[0096] Figure 13 It is a diagram showing an example of the setting process of CA in units of beams using RRC signaling in Embodiment 6.

[0097] Figure 14 It is a diagram showing an example of the setting process of CA in units of beams using RRC signaling in Embodiment 6.

[0098] Figure 15 It is a diagram showing an example of a MAC CE of beam activation / deactivation information in Modification 1 of Embodiment 6.

[0099] Figure 16 It is a diagram showing an example of the setting process of CA in units of beams using MAC signaling in Modification 1 of Embodiment 6.

[0100] Figure 17 It is a diagram showing an example of the setting process of CA in units of beams using MAC signaling in Modification 1 of Embodiment 6.

[0101] Figure 18 It is a diagram showing an example of the setting process of CA in units of beams using L1 / L2 signaling in Modification 2 of Embodiment 6.

[0102] Figure 19It is a diagram showing an example of the setting process of carrier aggregation (CA) in beam units using L1 / L2 signaling in Modification Example 2 of Embodiment 6.

[0103] Figure 20 It is a diagram showing an example of the setting process of carrier aggregation (CA) in beam units using L1 / L2 signaling in Modification Example 2 of Embodiment 6.

[0104] Figure 21 It is a diagram for explaining the DC (SCG bearer) setting method of this Embodiment 7.

[0105] Figure 22 It is a diagram for explaining the DC (split bearer) setting method of this Embodiment 7.

[0106] Figure 23 It is a diagram showing an example of the DC (SCG bearer) setting process of Embodiment 7.

[0107] Figure 24 It is a diagram showing an example of the DC (SCG bearer) setting process of Embodiment 7.

[0108] Figure 25 It is a diagram for explaining the DC (SCG bearer) setting method for each PDU session in Modification Example 1 of Embodiment 7.

[0109] Figure 26 It is a diagram for explaining the DC (SCG bearer) setting method for each PDU session in Modification Example 1 of Embodiment 7.

[0110] Figure 27 It is a diagram for explaining the DC (split bearer) setting method of Modification Example 1 of Embodiment 7.

[0111] Figure 28 It is a diagram for explaining another DC (split bearer) setting method of Modification Example 1 of Embodiment 7.

[0112] Figure 29 It is a diagram for explaining another DC (split bearer) setting method of Modification Example 1 of Embodiment 7.

[0113] Figure 30 It is a diagram for explaining the DC (SCG bearer) setting method for each PDU session in Modification Example 2 of Embodiment 7.

[0114] Figure 31 It is a diagram for explaining the DC (split bearer) setting method for each PDU session in Modification Example 2 of Embodiment 7. Detailed implementation mode

[0115] Embodiment 1.

[0116] Figure 2It is a block diagram showing the overall structure of a communication system 200 in the LTE mode discussed in 3GPP. The following Figure 2 will be described. The radio access network is called E-UTRAN (Evolved Universal Terrestrial Radio Access Network) 201. The communication terminal device, i.e., the mobile terminal device (hereinafter referred to as "mobile terminal (User Equipment: UE)") 202 can perform wireless communication with the base station device (hereinafter referred to as "base station (E-UTRAN NodeB: eNB)") 203, and use wireless communication to transmit and receive signals.

[0117] Here, the "communication terminal device" not only refers to mobile terminal devices such as mobile phone terminal devices that can move, but also includes immovable devices such as sensors. In the following description, the "communication terminal device" may sometimes be abbreviated as "communication terminal".

[0118] If the control protocols for the mobile terminal 202, such as RRC (Radio Resource Management), and the user planes, such as PDCP (Packet Data Convergence Protocol), RLC (Radio Link Control), MAC (Medium Access Control), and PHY (Physical layer), terminate at the base station 203, then the E-UTRAN is composed of one or more base stations 203.

[0119] The control protocol RRC between the mobile terminal 202 and the base station 203 performs broadcast, paging, RRC connection management, etc. The states of the base station 203 and the mobile terminal 202 in RRC are RRC_IDLE and RRC_CONNECTED.

[0120] In RRC_IDLE, PLMN (Public Land Mobile Network) selection, system information (SI) broadcasting, paging, cell re-selection, mobility, etc. are performed. In RRC_CONNECTED, the mobile terminal has an RRC connection and can transmit and receive data with the network. In addition, in RRC_CONNECTED, handover (HO), measurement of neighbour cells, etc. are performed.

[0121] 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 composed of an EPC (Evolved Packet Core) as a core network and an E-UTRAN 201 as a radio access network is called an EPS (Evolved Packet System). Sometimes, the EPC as a core network and the E-UTRAN 201 as a radio access network are collectively referred to as the "network".

[0122] The eNB 207 is connected to a mobility management entity (MME), or an S-GW (Serving Gateway), or an MME / S-GW unit (hereinafter sometimes referred to as the "MME unit") 204 including an MME and an S-GW through an S1 interface, and control information is communicated between the eNB 207 and the MME unit 204. For one eNB 207, a plurality of MME units 204 can be connected. The eNBs 207 are connected to each other through an X2 interface, and control information is communicated between the eNBs 207.

[0123] The Home-eNB 206 is connected to the MME unit 204 through an S1 interface, and control information is communicated between the Home-eNB 206 and the MME unit 204. One MME unit 204 is connected to a plurality of Home-eNBs 206. Alternatively, the Home-eNB 206 is connected to the MME unit 204 via a HeNBGW (Home-eNB GateWay) 205. The Home-eNB 206 and the HeNBGW 205 are connected through an S1 interface, and the HeNBGW 205 and the MME unit 204 are connected via an S1 interface.

[0124] One or more Home-eNBs 206 are connected to one HeNBGW 205 and communicate information through the S1 interface. The HeNBGW 205 is connected to one or more MME units 204 and communicates information through the S1 interface.

[0125] The MME unit 204 and the HeNBGW 205 are upper-level devices, specifically upper-level nodes, which control the 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 the core network. The base station 203 and the HeNBGW 205 constitute the E-UTRAN 201.

[0126] Furthermore, the following structure has been studied in 3GPP. The X2 interface between Home-eNBs 206 is supported. That is, the Home-eNBs 206 are connected to each other through the X2 interface and control information is communicated between the Home-eNBs 206. From the perspective of the MME unit 204, the HeNBGW 205 can be regarded as a Home-eNB 206. From the perspective of the Home-eNB 206, the HeNBGW 205 can be regarded as the MME unit 204.

[0127] Whether the Home-eNB 206 is connected to the MME unit 204 via the HeNBGW 205 or directly connected to the MME unit 204, the interface between the Home-eNB 206 and the MME unit 204 is the S1 interface in the same way.

[0128] The base station 203 can constitute one cell or multiple cells. Each cell has a pre-determined range as the coverage range within which it can communicate with the mobile terminal 202, and wireless communication is performed with the mobile terminal 202 within the coverage range. In the case where one base station 203 constitutes multiple cells, each cell is configured to be able to communicate with the mobile terminal 202.

[0129] Figure 3 It shows the communication terminal related to the present invention, that is Figure 2 the block diagram of the structure of the mobile terminal 202 shown. For Figure 3A description is given of the transmission processing of the mobile terminal 202 shown. First, the control data from the protocol processing unit 301 and the user data from the application unit 302 are stored in the transmission data buffer unit 303. The data stored in the transmission data buffer unit 303 is transmitted to the encoding unit 304 to perform encoding processing such as error correction. There may also be data that is output directly from the transmission data buffer unit 303 to the modulation unit 305 without performing encoding processing. The data after the encoding processing by the encoding unit 304 is subjected to modulation processing in the modulation unit 305. The modulated data is converted into a baseband signal and then output to the frequency conversion unit 306, where it is converted into a radio transmission frequency. After that, the transmission signal is transmitted from the antenna 307 to the base station 203.

[0130] In addition, the reception processing of the mobile terminal 202 is performed as follows. The radio signal from the base station 203 is received by the antenna 307. The received signal is converted from the radio reception frequency to a baseband signal by the frequency conversion unit 306 and subjected to demodulation processing in the demodulation unit 308. The demodulated data is transmitted to the decoding unit 309 to perform decoding processing such as error correction. Among the decoded data, the control data is transmitted to the protocol processing unit 301, and the user data is transmitted to the application unit 302. A series of processes of the mobile terminal 202 are controlled by the control unit 310. Thus, although it is omitted in Figure 3 the control unit 310 is connected to each of the units 301 to 309.

[0131] Figure 4 is a block diagram showing the structure of the base station according to the present invention, that is, Figure 2 the base station 203 shown. A description is given of Figure 4 the transmission processing of the base station 203 shown. The EPC communication unit 401 performs data transmission and reception between the base station 203 and the EPC (such as the MME unit 204), the HeNBGW 205, etc. The other base station communication unit 402 performs data transmission and reception with other base stations. The EPC communication unit 401 and the other base station communication unit 402 exchange information with the protocol processing unit 403 respectively. The control data from the protocol processing unit 403 and the user data and control data from the EPC communication unit 401 and the other base station communication unit 402 are stored in the transmission data buffer unit 404.

[0132] The data stored in the transmission data buffer unit 404 is transmitted to the encoding unit 405 to perform encoding processing such as error correction. There may also be data that is output directly from the transmission data buffer unit 404 to the modulation unit 406 without performing encoding processing. The encoded data is subjected to modulation processing in the modulation unit 406. The modulated data is converted into a baseband signal and then output to the frequency conversion unit 407, where it is converted into a radio transmission frequency. After that, using the antenna 408, the transmission signal is transmitted to one or more mobile terminals 202.

[0133] In addition, the receiving process of the base station 203 is performed as follows. The wireless signals from one or more mobile terminals 202 are received by the antenna 408. The received signals are frequency-converted from the wireless reception frequency to the baseband signal by the frequency conversion unit 407, and demodulation processing is performed in the demodulation unit 409. The data after demodulation is transmitted to the decoding unit 410 for decoding processing such as error correction. Among the decoded data, the control data is transmitted to the protocol processing unit 403, or the EPC communication unit 401, or the other base station communication unit 402, and the user data is transmitted to the EPC communication unit 401 and the other base station communication unit 402. A series of processes of the base station 203 are controlled by the control unit 411. Thus, although it is omitted in Figure 4 , the control unit 411 is connected to each unit 401 to 410.

[0134] Figure 5 is a block diagram showing the structure of the MME according to the present invention. Figure 5 In Figure 2 , the structure of the MME 204a included in the MME unit 204 shown above is shown. The PDN GW communication unit 501 performs data transmission and reception between the MME 204a and the PDN GW. The base station communication unit 502 performs data transmission and reception via the S1 interface between the MME 204a and the base station 203. When the data received from the PDN GW is user data, the user data is transmitted from the PDN GW communication unit 501 to the base station communication unit 502 via the user plane communication unit 503 and is transmitted to one or more base stations 203. When the data received from the base station 203 is user data, the user data is transmitted from the base station communication unit 502 to the PDN GW communication unit 501 via the user plane communication unit 503 and is transmitted to the PDN GW.

[0135] When the data received from the PDN GW is control data, the control data is transmitted from the PDN GW communication unit 501 to the control plane control unit 505. When the data received from the base station 203 is control data, the control data is transmitted from the base station communication unit 502 to the control plane control unit 505.

[0136] The HeNBGW communication unit 504, in the presence of the HeNBGW 205, performs data transmission and reception via the interface (IF) between the MME 204a and the HeNBGW 205 according to the type of information. The control data received by the HeNBGW communication unit 504 is transmitted from the HeNBGW communication unit 504 to the control plane control unit 505. The processing result in the control plane control unit 505 is sent to the PDN GW via the PDN GW communication unit 501. In addition, the result processed by the control plane control unit 505 is sent to one or more base stations 203 via the base station communication unit 502 through the S1 interface, or is sent to one or more HeNBGWs 205 via the HeNBGW communication unit 504.

[0137] 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 all processing on the control plane. The NAS security unit 505-1 is responsible for the security of NAS (Non-Access Stratum) messages, etc. The SAE bearer control unit 505-2 manages the bearers of SAE (System Architecture Evolution), etc. The idle state mobility management unit 505-3 performs mobility management in the standby state (also referred to as the idle state; LTE-IDLE state, or simply idle), generates and controls paging signals in the standby state, adds, deletes, updates, retrieves, and manages the tracking areas of one or more mobile terminals 202 within the coverage area, etc.

[0138] The MME 204a distributes paging signals to one or more base stations 203. The MME 204a performs mobility control in the idle state. The MME 204a manages the tracking area list when the mobile terminal is in the standby state and the active state. The MME 204a starts the paging protocol by sending a paging message to the cell belonging to the tracking area where the UE is registered. The management of the CSG of the Home-eNB 206 connected to the MME 204a, the management of the CSGID, and the white list management can be performed by the idle state mobility management unit 505-3.

[0139] Next, an example of a cell search method in the communication system is shown. Figure 6It is a flowchart showing an overview of the operations from cell search to standby by a communication terminal (UE) in a communication system using the LTE mode. When the communication terminal starts cell search, in step ST601, it acquires synchronization of the time slot timing and frame timing by using the first synchronization signal (P-SS) and the second synchronization signal (S-SS) transmitted from surrounding base stations.

[0140] The P-SS and S-SS are collectively referred to as the synchronization signal (Synchronization Signal: SS). Synchronization codes corresponding one-to-one to the PCI assigned to each cell are allocated in the synchronization signal (SS). It is considered that the number of PCI is 504. Synchronization is acquired by using these 504 PCI, and the PCI of the cell for which synchronization is acquired is detected (determined).

[0141] Next, in step ST602, the cell-specific reference signal (CRS), which is the reference signal (reference signal: RS) transmitted from the base station to each cell for the cell for which synchronization has been acquired, is detected, and the received power of the RS (Reference Signal Received Power: RSRP) is measured. The reference signal (RS) uses coding corresponding one-to-one to the PCI. Correlation can be acquired by using this coding to separate from other cells. By deriving the coding for the RS of this cell based on the PCI determined in step ST601, the RS can be detected and the received power of the RS can be measured.

[0142] Next, in step ST603, the cell with the best reception quality of the RS is selected from among the one or more cells detected up to step ST602. For example, the cell with the highest received power of the RS, i.e., the best cell, is selected.

[0143] Next, in step ST604, the PBCH of the best cell is received to obtain the broadcast information, i.e., the BCCH. Since the MIB (Master Information Block: master information block) containing cell structure information is mapped in the BCCH on the PBCH, the MIB can be obtained by receiving the PBCH and obtaining the BCCH. As information in the MIB, for example, there are DL (downlink) system bandwidth (also referred to as transmission bandwidth configuration: dl-bandwidth), number of transmission antennas, SFN (System Frame Number), etc.

[0144] Next, in step ST605, the DL-SCH of the cell is received based on the cell structure information in the MIB, and SIB (System Information Block) 1 in the broadcast information BCCH is obtained. SIB1 contains information related to accessing the cell, information related to cell selection, and scheduling information for other SIBs (SIBk; k is an integer greater than or equal to 2). In addition, SIB1 contains the Tracking Area Code (TAC).

[0145] Next, in step ST606, the communication terminal compares the TAC of SIB1 received in step ST605 with the TAC part of the Tracking Area Identity (TAI) in the tracking area list already saved by the communication terminal. The tracking area list is also referred to as the TAI list. TAI is identification information for identifying a tracking area, and is composed of MCC (Mobile Country Code), MNC (Mobile Network Code), and TAC (Tracking Area Code). MCC is the country code. MNC is the network code. TAC is the code number of the tracking area.

[0146] If the result of the comparison in step S606 is that the TAC received in step ST605 is the same as the TAC included in the tracking area list, the communication terminal enters the standby operation in this cell. If the comparison result is that the TAC received in step ST605 is not included in the tracking area list, the communication terminal requests a tracking area change to the core network (Core Network, EPC) including the MME, etc. through this cell to perform a Tracking Area Update (TAU).

[0147] The device constituting the core network (hereinafter sometimes referred to as the "core network side device") updates the tracking area list based on the TAU request signal and the identification number (UE-ID, etc.) of the communication terminal sent from the communication terminal. The core network side device sends the updated tracking area list to the communication terminal. The communication terminal rewrites (updates) the TAC list stored in the communication terminal based on the received tracking area list. Thereafter, the communication terminal enters the standby operation in this cell.

[0148] Due to the popularization of smartphones and tablet terminal devices, the traffic volume using cellular system wireless communication has increased explosively, and thus there are concerns about the shortage of wireless resources worldwide. To address this situation and improve the frequency utilization efficiency, research has been conducted on the miniaturization of cells and the promotion of spatial separation.

[0149] In the existing cell structure, a cell formed by an eNB has a relatively wide coverage area. Conventionally, a cell structure is configured to cover a certain area by using the relatively wide coverage areas of multiple cells formed by multiple eNBs.

[0150] In the case of miniaturizing a cell, compared with the coverage area of a cell formed by an existing eNB, a cell formed by an eNB has a relatively narrow coverage area. Therefore, as in the prior art, in order to cover a certain area, a large number of eNBs after cell miniaturization are required compared with existing eNBs.

[0151] In the following description, a cell with a relatively large coverage area, such as a cell formed by using an existing eNB, is referred to as a "macro cell", and the eNB forming the macro cell is referred to as a "macro eNB". In addition, a cell with a relatively small coverage area, such as a cell after cell miniaturization, is referred to as a "small cell", and the eNB forming the small cell is referred to as a "small eNB".

[0152] The macro eNB can be, for example, a "Wide Area Base Station" described in Non-Patent Document 7.

[0153] The small eNB can be, for example, a low-power node, a local node, a hot spot, etc. The small eNB can be a pico eNB forming a pico cell, a femto eNB forming a femto cell, a HeNB, an RRH (Remote Radio Head), an RU (Remote Radio Unit), an RRE (Remote Radio Equipment), or an RN (relay node). The eNB can be a "Local Area Base Station" or a "Home Base Station" described in Non-Patent Document 7.

[0154] Figure 7 It is a diagram showing the concept of a cell structure when macro eNBs and small eNBs are mixed together. The macro cell formed by the macro eNBs has a relatively large coverage area 701. The small cell formed by the small eNBs has a coverage area 702 that is smaller than the coverage area 701 of the macro eNBs (macro cell).

[0155] When multiple eNBs are mixed together, the coverage area of a cell formed by a certain eNB may be included in the coverage area of a cell formed by other eNBs. Figure 7In the structure of the cell shown, as indicated by reference numeral "704" or "705", the coverage area 702 of the small cell formed by the small eNB is sometimes included in the coverage area 701 of the macro cell formed by the macro eNB.

[0156] In addition, as indicated by reference numeral "705", there are also cases where the coverage areas 702 of multiple, for example, two small cells are included in the coverage area 701 of one macro cell. The mobile terminal (UE) 703 is included in the coverage area 702 of the small cell, for example, and communicates via the small cell.

[0157] In addition, in Figure 7 In the structure of the cell shown, as indicated by reference numeral "706", the following situation will occur, that is, the coverage area 701 of the macro cell formed by the macro eNB and the coverage area 702 of the small cell formed by the small eNB are complexly repeated.

[0158] In addition, as indicated by reference numeral "707", the following situation will also occur, that is, the coverage area 701 of the macro cell formed by the macro eNB and the coverage area 702 of the small cell formed by the small eNB do not overlap.

[0159] Furthermore, as indicated by reference numeral "708", the following situation will also occur, that is, the coverage areas 702 of multiple small cells formed by multiple small eNBs are formed within the coverage area 701 of one macro cell formed by one macro eNB.

[0160] In LTE handover, the target cell generates the parameters (such as cell ID, etc.) used by the UE in the handover target, and the generated parameters are notified to the UE as RRC signaling from the source cell (refer to Non-Patent Document 1).

[0161] In NR, communication using beams is studied. In NR, the beams belonging to the UE are frequently switched due to the movement of the UE. Therefore, in the movement between the beams of the UE, the mobility without using RRC is studied (refer to Non-Patent Document 11).

[0162] In addition, in 3GPP, a solution is proposed to separate the gNB into two units (refer to Non-Patent Document 7). These two units are respectively called CU (Central Unit) and DU (Distributed Unit). Multiple DUs are connected to the CU. For example, a solution is proposed where the CU has PDCP, RLC, MAC, and H-PHY. A solution is proposed where the DU has L-PHY. As another method, a solution is proposed where the CU has PDCP, the DU has RLC, MAC, and PHY, or a solution where the CU has PDCP and H-RLC, and the DU has L-RLC, MAC, and PHY. The TRP can have the same functions as the DU. The DU or TRP forms one or more beams.

[0163] In addition, it is studied that during the movement between the beams of the UE or the TRP (Transmission / Reception Point), when the TRP has the Layer 2 function, inter-cell mobility is performed, that is, mobility using RRC signaling, and when the TRP does not have the Layer 2 function, inter-beam mobility is performed, that is, mobility without using RRC signaling (refer to 3GPP R2-167024 (hereinafter referred to as "Reference 1")).

[0164] In the communication using multiple beams or multiple TRPs in NR, the communicable space is separated by each beam or each TRP.

[0165] Figure 8 It is a diagram showing that multiple beams or TRPs separate the communicable space. In Figure 8 the gNB800 is composed of one CU (Central Unit) and two DUs (Distributed Units). DU#1 801 and DU#2 802 are respectively connected to the CU803. The DU can be a TRP.

[0166] Figure 8 In it, DU#1 has Beam #1 804, Beam #2 805, and Beam #3 806, and DU#2 has Beam #4807, Beam #5 808, Beam #6 809, and Beam #7 810. The cell 811, that is, the communicable space of the gNB, is separated from each other by Beam #1 804 to Beam #7 810.

[0167] Figure 8 In it, one DU can be used, or multiple DUs can be used. In addition, the CU and the DU may not be separated and may be configured as one device.

[0168] However, in the case where a cell is spatially separated by each beam or each TRP as described above, there is no disclosure on how to handle the RRC parameters.

[0169] Embodiment 1 discloses a method for solving the above problems.

[0170] Within a beam or a TRP belonging to a cell, the same RRC parameters are shared for one UE. The RRC parameters may be the parameters shown in Section 6.3.2 of Non-Patent Document 12. The RRC parameters may be, for example, parameters related to SR, parameters related to Ack / Nack repetition, parameters related to Sounding Reference Signal (SRS), or parameters related to CQI / CSI.

[0171] During the process of sharing the RRC parameters, the CU of the gNB can notify each TRP within the cell of the RRC parameters. This notification can be specifically for the RRC parameters related to the physical layer. The RRC parameters related to the physical layer may be, for example, parameters indicating the frequency resources of the SRS. Thus, modulation and demodulation in each TRP can be easily implemented.

[0172] Alternatively, the parameters required for beam scanning can be shared within a beam or a TRP belonging to a cell. As the parameters required for beam scanning, for example, it can be the period of beam scanning, the duration of one beam scanning, or the time required for one beam. The above parameters can be set as new RRC parameters. Thus, the UE can easily receive the beam scanning signal during the movement between beams / TRPs.

[0173] The CU can notify each TRP within the cell of the parameters required for beam scanning. Thus, the transmission of the beam scanning signal in each TRP can be easily implemented.

[0174] In the above, for example, the area of the control word of CPRI (Common Public Radio Interface) can be used for the RRC parameter notification from the CU to the TRP. This control word can be used when CPRI is used for the CU-DU interface. Thus, the RRC parameters can be notified without occupying the frequency band of the user data flowing between the CU and the DU on the CPRI.

[0175] In the above, the RRC parameter notification from the CU to the TRP can use the format of ASN.1 (Abstract Syntax Notation One), or other formats. By using ASN.1, the DU can notify the parameters to the TRP in the same format as the RRC signaling, so the process of the DU notifying the RRC parameters to the TRP becomes simple.

[0176] Through Embodiment 1, even if there are multiple beams or TRPs in a cell, RRC parameters can be managed in the CU. In addition, the same RRC parameters are shared between beams or between TRPs within the cell, thereby simplifying radio resource management in the CU.

[0177] According to Embodiment 1, the following communication system is provided. The communication system includes, for example, a communication terminal device and a base station device that performs wireless communication with the communication terminal device using a wireless beam. A cell formed by the base station device is spatially separated by a plurality of wireless beams subordinate to the base station device, and the base station device shares RRC (Radio Resource Control) parameters for the communication terminal device among the plurality of wireless beams belonging to the same cell. In addition, the plurality of wireless beams can be formed by a plurality of DUs (in other words, TRPs) as Figure 8 illustrated, or can be formed by one DU.

[0178] According to this structure, RRC parameters for the communication terminal device can be shared among two or more of the plurality of wireless beams that spatially separate the cell formed by the base station device. Therefore, radio resource management can be simplified as described above. Here, the above structure can be variously modified as described above. In addition, in Embodiment 1, an example in which RRC parameters are shared by all wireless beams belonging to the same cell is described, but the above structure is not limited to this example (for example, refer to Embodiment 8 and its modified examples described later).

[0179] Embodiment 2.

[0180] In Embodiment 1, a case where RRC parameters are shared between different beams or different TRPs within a cell is shown, but RRC parameters may not be shared. The RRC parameters can be the same as those in Embodiment 1. As a result, different UEs existing within the coverage ranges of different beams or different TRPs do not need to compete for the use of the same RRC parameters, and thus the number of UEs accommodated in the cell can be increased.

[0181] However, when the CU and DU are separated as described in Embodiment 1, for example, when the CU has PDCP, RLC, MAC, and H-PHY, RRC signaling cannot be used as described in Embodiment 1 during movement between beams or between TRPs within the cell. Therefore, RRC parameters cannot be notified from the gNB to the UE. The same applies to a base station device in which the CU and DU are not separated, and RRC parameters cannot be notified from the gNB to the UE during movement between beams within the cell. As a result, there is a problem that the number of UEs accommodated in the cell cannot be increased.

[0182] This Embodiment 2 discloses a method for solving the above problems.

[0183] The CU notifies the UE in advance of the RRC parameters used for the beams or TRPs (hereinafter sometimes referred to as beam / TRPs) within the cell. The CU can perform this notification using RRC signaling. The CU can perform this notification at the start of the UE's RRC connection or when the RRC parameters are changed.

[0184] During the handover of the beam / TRP, the CU notifies the UE of a beam / TRP handover indication. This handover indication may include an identifier indicating the target beam / TRP for movement. The CU can notify the UE of this handover indication using L1 / L2 signaling or using MAC signaling.

[0185] Thereby, the CU can implement parameter changes accompanying the beam / TRP handover with a smaller amount of signaling.

[0186] The above notification of the RRC parameters may consist only of the RRC parameters used in the beam / TRPs near the UE. The above-mentioned nearby beam / TRPs may include the beam / TRPs adjacent to the beam / TRP where the UE is located. In addition, the RRC parameters included in this notification may also consist only of the parameters different from those used by the beam / TRP where the UE is located. Thereby, the size of this notification can be reduced.

[0187] Other methods are also disclosed. During the handover of the beam or TRP, the CU notifies the UE of the RRC parameters used by the target beam / TRP for movement. This notification can be performed via the source beam / TRP. The RRC parameters can be the parameters shown in Section 6.3.2 of Non-Patent Document 12 in the same manner as in Embodiment 1. The RRC parameters can be, for example, parameters related to SR, parameters related to Ack / Nack repetition, parameters related to the Sounding Reference Signal (SRS), or parameters related to CQI / CSI.

[0188] Thereby, the above RRC signaling from the CU to the UE is not required, and thus the beam / TRP handover can be implemented with a smaller amount of signaling.

[0189] The CU can notify the UE of the parameters required for beam scanning. The parameters required for beam scanning can be set as the parameters shown in Embodiment 1. This notification can be performed via the source beam / TRP. The parameters required for beam scanning can be set as the parameters in the target beam / TRP. Thereby, the UE can easily receive the beam scanning signal during the movement between the beam / TRPs.

[0190] The notification of the parameters required for beam scanning from the CU to the UE described above can be carried out using L1 / L2 signaling or MAC signaling. Thereby, the parameters required for beam scanning can be notified quickly.

[0191] The CU notifies the UE of a beam / TRP handover indication (hereinafter sometimes simply referred to as "handover indication") via the mobile source beam / TRP. The handover indication may include an identifier indicating the mobile target beam / TRP. In addition, the handover indication may include information indicating the timing of the beam / TRP handover.

[0192] In the above, when the CU determines the mobile target beam / TRP, the beam measurement result notified by the UE to the CU can be used. The measurement result can be, for example, the beam reception intensity or the beam reception quality.

[0193] The handover indication may include an identifier indicating the mobile target beam / TRP. The CU and the UE can automatically determine the mobile target beam / TRP based on the measurement result of the beam / TRP. The measurement result of the beam / TRP can be, for example, the reception intensity of each beam or the reception quality. Thereby, the signaling amount of the handover indication can be reduced.

[0194] As the RRC parameters related to SR in the above, the following (1) to (3) are shown.

[0195] (1) Parameters for determining the RB (Resource Block) and code for SR. For example, sr-PUCCH-ResourceIndex described in Non-Patent Document 12.

[0196] (2) The transmission period and subframe offset of SR. For example, sr-ConfigIndex described in Non-Patent Document 12.

[0197] (3) The combination of (1) and (2) above.

[0198] According to the above (1), by preventing the position of the RB for SR from competing with other UEs due to the movement of the UE between beams / TRPs, the number of UEs that can be accommodated in one beam / TRP can be increased.

[0199] According to the above (2), by preventing the SR transmission timing from competing with other UEs due to the movement of the UE between beams / TRPs, the number of UEs that can be accommodated in one beam / TRP can be increased.

[0200] In the above (2), only the subframe offset sent by the SR may be changed. In addition, when the subframe offset is changed, only the information of the subframe offset may be notified. Thus, for the SR transmission of multiple UEs in the mobile target beam / TRP, it can be easily adjusted by the CU to avoid competition among UEs. In addition, by only notifying the information of the subframe offset, the amount of bits sent from the CU to the UE can be reduced.

[0201] The parameter notified as the above (1) to (3) may be the value itself or the change amount of the value. By using the value itself, the process of parameter notification from the CU to the UE becomes easy. In addition, by using the change amount of the value, the number of bits required for parameter notification can be reduced.

[0202] The CU may simultaneously notify multiple parameters to the UE in the RRC parameters including the above (1) to (3). Thus, the amount of signaling required for notification can be reduced.

[0203] The CU may separately notify the RRC parameters including the above (1) to (3) to the UE. Thus, the parameters can be notified even in the case of less transmission resources.

[0204] The CU may notify the UE of a parameter indicating the maximum number of retransmissions of the SR as an RRC parameter related to the SR, or may not notify it. The parameter indicating the maximum number of retransmissions may be, for example, dsr-TransMax described in Non-Patent Document 12. By notifying the parameter, for example, when the transmission environment is poor, the parameter is changed to a smaller value, so that the UE can quickly transfer to the random access process after exceeding the SR retransmission number. Thus, the process of beam / TRP movement can be completed quickly.

[0205] In the notification of the RRC parameter from the CU to the UE, an identifier indicating the parameter switch caused by the TRP / beam switching may be included. The UE may hold the RRC parameter before the change. Thus, the UE can prevent the RRC parameter from being changed before the TRP / beam switching, and thus can prevent, for example, the SR from not being delivered to the mobile source TRP / beam due to the above parameter change during the SR transmission.

[0206] Regarding the notification of the RRC parameter, the CU may not notify the parameter using the same value in the mobile target beam / TRP. Thus, the amount of signaling generated by the parameter notification can be reduced.

[0207] The CU and the UE may restore the value of the RRC parameter to the initial value when the beam / TRP of the UE is switched. For example, it may be changed to the initial value when the parameter notification from the mobile source beam / TRP to the UE fails. The initial value may be determined by the standard or may be notified from the CU to the UE in advance using the RRC signaling. Thus, even when the parameter notification from the mobile source beam / TRP to the UE fails, the UE can continue to communicate with the CU using the initial value.

[0208] Alternatively, the CU and the UE in the above can maintain the values of the parameters. The maintenance of the parameter values can be performed, for example, when the parameter notification from the CU to the UE fails. Thus, even when the parameter notification from the mobile source beam / TRP to the UE fails, the UE can use the RRC parameters before the change. Therefore, for example, when the same RRC parameters as those of the mobile source beam / TRP are used in the mobile target beam / TRP, the UE can prevent the SR from not being sent to the mobile target beam / TRP.

[0209] Regarding whether the parameter values at the time of beam / TRP switching of the UE in the above are restored to the initial values or maintained, it can be determined by the standard or notified from the CU to the UE in advance. RRC signaling can be used in this notification. Alternatively, the information on whether to restore to the initial values or maintain can be notified from the CU to the UE together with the handover indication. Thus, the CU can flexibly set the parameters according to the usage status of the RRC parameters of the subordinate UE.

[0210] The CU can notify the RRC parameters to the UE together with the handover indication. Thus, the signaling amount in the beam / TRP switching can be reduced.

[0211] Alternatively, the CU can notify the handover indication to the UE after the RRC parameter notification. Thus, the CU can notify the handover indication to the UE after confirming the delivery of the RRC parameters. Therefore, it is possible to avoid, for example, the SR from the UE not being sent due to the non-delivery of the RRC parameters related to the SR and the execution of random access due to exceeding the retransmission count.

[0212] Alternatively, the CU can notify the RRC parameters to the UE after the handover indication notification. In this case, the CU can notify the handover indication and the handover timing to the UE together. Thus, even if the process of switching the communication target beam / TRP in the UE takes time, the handover can be smoothly performed.

[0213] The CU can notify the RRC parameters to the UE by using L1 / L2 signaling. Thus, the parameters can be quickly notified to the UE.

[0214] Alternatively, the CU can use MAC signaling to notify the RRC parameters. Thus, multi-level modulation can be performed, and the parameters can be notified with fewer symbols. In addition, HARQ retransmission control is performed, so the reliability of the parameter notification is improved. In addition, the CU can notify the handover indication to the UE after confirming the delivery of the parameters. Therefore, for example, it is possible to avoid the SR from the UE not being sent due to the non-delivery of the parameters and the execution of random access due to exceeding the SR retransmission count.

[0215] The CU can notify the RRC parameters to the mobile target beam / TRP. Similar to Embodiment 1, in this notification, for example, the area of the control word of CPRI can be used, the ASN.1 format can be used, or other formats can be used. Thus, in addition to the same effects as Embodiment 1, for example, immediately after beam / TRP switching, the mobile target beam / TRP can quickly decode the SR from the UE.

[0216] The CU can use L1 / L2 signaling to notify the handover indication to the UE. Thus, the beam / TRP handover can be quickly notified to the UE.

[0217] Alternatively, the CU can use MAC signaling to notify the handover indication. The CU can switch the beam / TRP for its own use after receiving the Ack for the handover indication from the UE. The UE can also switch the communication target beam / TRP after sending the Ack for the handover indication. Thus, the reliability of notifying the handover indication from the CU to the UE is improved, and the possibility of the UE suffering from RLF (Radio Link Failure) due to the loss of the link with the gNB can be reduced.

[0218] In the above notification of the handover indication using MAC signaling, the CU can switch the beam / TRP when the handover indication from the mobile source beam / TRP to the UE exceeds the HARQ retransmission count. The beam / TRP can be switched when it is impossible to distinguish the Ack / Nack from the UE for the handover indication. Thus, when the mobile source beam / TRP fails to receive the Ack signal from the UE for the handover indication, the communication target beam / TRP can be switched in the UE and the beam / TRP can also be switched in the gNB. Thus, the loss of the link between the UE and the gNB can be prevented.

[0219] Alternatively, in the above, the CU can not switch the beam / TRP when the handover indication from the mobile source beam / TRP to the UE exceeds the HARQ retransmission count. In this case, the UE can communicate with the mobile source beam / TRP again after the RLF caused by the loss of the link with the gNB is recovered. Thus, the beam switching control in the CU becomes simple.

[0220] Figure 9 It is a flowchart showing the beam / TRP handover when notifying the parameters related to SR from the CU via the mobile source beam / TRP. Figure 9 It shows an example of notifying the parameters related to SR and the handover indication from the CU to the UE using MAC signaling. Figure 9 In it, the mobile source beam / TRP under the CU is denoted as S-beam / TRP, and the mobile target beam / TRP under the CU is denoted as T-beam / TRP. In addition, Figure 9Among them, the black circle in the arrow represents the beam / TRP for communication.

[0221] According to Figure 9 , in step ST901 before beam / TRP switching, the UE transceives user data with the CU via the S-beam / TRP.

[0222] Figure 9 In step ST902 of , the CU notifies the UE of the SR parameters via the S-beam / TRP. MAC signaling is used in this notification. L1 / L2 signaling can also be used. In addition, the SR parameters can include the sr-PUCCH-ResourceIndex shown in Non-Patent Document 12, or can include the sr-ConfigIndex shown in Non-Patent Document 12. In step ST903, the UE notifies the CU of the Ack for the SR parameter notification via the S-beam / TRP. In the case where the reception result from the UE is Nack, the CU can retransmit the SR parameters via the S-beam / TRP.

[0223] Figure 9 In step ST904 of , the CU notifies the UE of the handover indication via the S-beam / TRP. The notification of the handover indication can use MAC signaling. L1 / L2 signaling can also be used. The CU can include information indicating the T-beam / TRP in the handover indication. In step ST905, the UE notifies the CU of the Ack for the handover indication via the S-beam / TRP. In the case where the reception result from the UE is Nack, the CU can retransmit the handover indication via the S-beam / TRP.

[0224] Figure 9 In step ST906 of , the UE switches the beam / TRP of the communication target from the S-beam / TRP to the T-beam / TRP. In step ST907, the CU switches the beam / TRP from the S-beam / TRP to the T-beam / TRP. In step ST908, the CU communicates user data with the UE via the T-beam / TRP.

[0225] The UE can send an uplink signal to the beam / TRP of the mobile source. The uplink signal can be a response to the L1 / L2 signaling for the RRC parameter notification from the CU. The uplink signal can also be a response to the L1 / L2 signaling for the handover indication from the CU. As the uplink signal, response-used L1 / L2 signaling can be additionally set. As the above response, new uplink control information (UCI) can be set. Thus, even when L1 / L2 signaling is used in the RRC parameter notification or handover indication from the CU, the CU can perform delivery confirmation to the UE. Thus, the reliability of the above L1 / L2 signaling can be improved.

[0226] Alternatively, the UE may send an uplink signal to the beam / TRP of the mobile target. The uplink signal may be set as a signal for confirming beam / TRP switching in the UE. The frequency resources of the SR may be used to send the confirmation signal. Alternatively, the SR may be sent as the confirmation signal. Thereby, the frequency resources for the uplink signal can be saved.

[0227] Alternatively, a new UCI may be sent. As the new UCI resource, the CU may allocate it for each UE. The CU may include the information of the UCI resource in the notification that requires a response from the UE. As the notification that requires a response, for example, it may be a handover notification or a parameter change notification. Thereby, the CU can flexibly allocate the new UCI resource to the UE according to the idle status of the resources.

[0228] As other examples of the new UCI resource, a shared resource shared by the UEs in the cell may be prepared. The shared resource may use the PRACH, for example, a shared resource for the SR may be prepared, or other shared resources may be set. Thereby, since the CU does not need to notify the UE of the information of the new UCI resource, the signaling amount can be reduced.

[0229] As the above uplink signal, the UE may send the SR to the beam / TRP of the mobile target at the minimum period. Thereby, it can be confirmed with low latency that the UE has switched the communication target beam / TRP.

[0230] In the above, the CU may ensure a shared resource for the SR shared by the UEs existing within the coverage of the same beam / TRP. The UE may use the shared resource for the SR to send the SR. The shared resource for the SR may be a resource that allows the UEs to compete with each other (contention-based). The location of the shared resource for the SR may be determined in advance by the standard or notified by the CU to the subordinate UEs. This notification may be a broadcast or a UE-specific notification. The UE-specific notification in the above may be RRC dedicated signaling. Thereby, even when the UE fails to receive the RRC parameters, it can notify the CU that the beam / TRP switching has been performed.

[0231] The UE may use the initial value of the RRC parameters related to the SR at the time of beam / TRP switching of the communication target as the SR shared resource. Thereby, even when the UE fails to receive the RRC parameters, it can notify the CU that the beam / TRP switching has been performed.

[0232] The UE in the above can also send the SRS to the beam / TRP of the mobile target. The SRS can be either aperiodic or periodic. The UE can send the SRS to the beam / TRP of the mobile target a predetermined number of times. This number of transmissions can be determined by the standard or can be notified to the UE by the CU in advance. The above notification can be carried out using RRC signaling. Thus, even when there is no uplink user data sent to the CU, the UE can notify the CU of the situation where the communication target beam / TRP has been switched.

[0233] The CU can use the above SR to determine whether there is a communication target beam / TRP switch in the UE. For example, in the case where there is no SR notification from the UE, the CU can determine that the UE has not switched the communication target beam / TRP. The CU can re-notify the RRC parameters and the handover indication from the mobile source beam / TRP. This re-notification can be carried out using the above determination result. Thus, for example, it is possible to prevent RLF or random access processing caused by the UE failing to receive the parameters or handover indication related to the SR. Thus, the time for beam / TRP switching can be shortened.

[0234] The CU can notify the UE of the request for sending an uplink signal to the UE. The presence or absence of this request can be for the uplink signal to the mobile source beam / TRP and the uplink signal to the mobile target beam / TRP respectively. The presence or absence of this request can be included in the handover indication from the CU to the UE. Thus, for example, when the communication quality is excellent, a response from the UE can be dispensed with, so the signaling volume can be reduced.

[0235] The CU can notify the RRC parameters to the UE multiple times. Thus, the reliability of parameter notification can be improved. This number of notifications can be determined by the standard or can be notified to the UE by the gNB in advance. The above notification can be carried out using RRC signaling.

[0236] The CU can increase the transmission power for notifying the RRC parameters to the UE. Thus, the reliability improvement of parameter notification can be achieved with a smaller number of notifications. The increase amount of this power can be determined by the standard or can be notified to the UE by the CU in advance. The above notification can be carried out using RRC signaling.

[0237] Regarding the handover indication notification to the UE, similar to the notification of the RRC parameters, it can be sent multiple times or the power can be increased. Thus, the reliability of the handover indication notification can be improved.

[0238] The UE uses the notification of RRC parameters received from the mobile source beam / TRP to switch the beam / TRP of the communication target. The switching of the beam / TRP may be accompanied by beam scanning and random access. The switching of the beam / TRP can be performed by receiving more than one RRC parameter. The switching of the beam / TRP can be performed after a predetermined time has elapsed after the UE has received more than one of the above parameters. The above-mentioned predetermined time can be determined by a standard or can be notified to the UE by the CU in advance. This notification can be performed using RRC signaling. Thus, even in the case where the UE cannot correctly receive the handover indication from the CU to the UE, the UE can switch the beam / TRP of the communication target. In addition, there is no need for the time required to retransmit the handover notification from the CU to the UE.

[0239] Among the above, the CU may include information indicating the mobile target beam / TRP in the notification of the parameter. Thus, in the beam / TRP switching of the UE performed in the case where the UE cannot correctly receive the handover indication from the CU to the UE, the time for the UE to search for the handover target beam / TRP can be shortened.

[0240] For the SR transmission from the UE, the CU may invalidate the SR received by the mobile source beam / TRP. When a beam / TRP switch occurs between SR reception and uplink scheduling grant transmission, the CU may invalidate the SR. Among the above, the UE may retransmit the SR to the mobile target beam / TRP. Thus, the implementation of the SR transmission process in the UE can be made easier.

[0241] Alternatively, regarding the beam / TRP switch after the above SR transmission from the UE, the CU may make the SR received by the mobile source beam / TRP valid. The CU may send the uplink scheduling grant for the SR to the UE through the mobile target beam / TRP. Thus, the uplink data communication when the beam / TRP switch occurs can be smoothly performed.

[0242] Whether the above SR is made valid can be determined by a standard. Or it can be notified to the UE by the CU. This notification can be performed in advance using RRC signaling, can be performed using MAC signaling, or can be performed using L1 / L2 signaling. In the example where MAC signaling or L1 / L2 signaling is used, this notification can be performed together with the handover notification. Thus, the scheduling of the uplink data communication in the CU can be flexibly performed.

[0243] Regarding the uplink scheduling grant notification from the CU to the UE, the CU and the UE can invalidate the uplink scheduling grant sent from the mobile source beam / TRP. When a beam / TRP handover occurs between the uplink scheduling grant and the uplink user data, the CU and the UE can invalidate the uplink scheduling grant. In the above, the CU can retransmit the uplink scheduling grant from the mobile target beam / TRP. Alternatively, the UE can restart the SR transmission for the mobile target beam / TRP. In the above, whether the UE restarts from the SR transmission is determined by the standard. Or it can be notified to the UE by the gNB. The above notification can be preformed by RRC signaling, can be preformed by MAC signaling, or can be preformed by L1 / L2 signaling. In an example where the above notification is preformed by MAC signaling or L1 / L2 signaling, the above notification can be performed together with the handover notification. Thereby, the gNB can perform scheduling corresponding to the uplink resource usage status in the mobile target beam / TRP.

[0244] Alternatively, regarding the beam / TRP handover after the uplink scheduling grant notification from the CU to the UE in the above, the CU and the UE can validate the uplink scheduling grant sent from the mobile source beam / TRP. The UE can use the uplink scheduling grant to send uplink user data to the mobile target beam / TRP. Thereby, the signaling volume between the CU and the UE can be reduced.

[0245] It can be determined by the standard whether to validate the uplink scheduling grant as above, or it can be notified from the CU to the UE. The notification from the CU to the UE can be preformed by RRC signaling, can be preformed by MAC signaling, or can be preformed by L1 / L2 signaling. As an example of the case where the uplink scheduling grant is validated, it can be set as the case where the mobile target beam / TRP can use the uplink resources indicated by the scheduling grant for this UE. In an example where the above notification is preformed by MAC signaling or L1 / L2 signaling, the above notification can be performed together with the handover notification. Thereby, the CU can perform scheduling corresponding to the uplink resource usage status in the mobile target beam / TRP with less signaling.

[0246] For the uplink user data transmission from the UE to the CU, the CU can send an Ack / Nack for the uplink user data received from the UE from the mobile target beam / TRP for the mobile source beam / TRP to the UE. The above Ack / Nack transmission from the mobile target beam / TRP can be performed when a beam / TRP handover occurs between the uplink user data transmission from the UE and the Ack / Nack notification from the CU. Thereby, the beam / TRP handover after the uplink user data transmission can be smoothly performed.

[0247] According to Embodiment 2, it is possible to notify a UE of RRC parameters from a CU during beam / TRP movement within a cell, and it is possible to increase the number of UEs accommodated in a cell spatially separated by beams / TRPs. In addition, compared with notification based on RRC signaling, parameters can be notified more quickly.

[0248] In Embodiment 2, a base station device in which a CU and a DU are separated is shown as an example, but it can also be applied to a base station device in which a CU and a DU are not separated. This base station device may be a base station device that does not share RRC parameters between beams. When applying Embodiment 2 to this base station device, a gNB can be used to replace the CU. Thus, during beam movement within a cell, it is possible to notify a UE of RRC parameters from the gNB via a source beam, and it is possible to increase the number of UEs accommodated in a cell spatially separated by beams. Parameters can be notified from the gNB to the UE more quickly.

[0249] In Embodiment 2, a base station device that notifies RRC parameters to a UE using a source beam / TRP is shown as an example, but other beams / TRPs can also be used to notify RRC parameters. The above-mentioned other beams / TRPs can be, for example, beams / TRPs for transmitting control information. Thus, for example, in a base station device having beams / TRPs for user data transmission / reception and control information transmission / reception, RRC parameters can be notified with a smaller amount of signaling. Therefore, RRC parameter notification can be performed more quickly during beam movement.

[0250] According to Embodiment 2, there is provided a communication system that includes, for example, a communication terminal device and a base station device that performs wireless communication with the communication terminal device using a wireless beam. A cell formed by the base station device is spatially separated by a plurality of wireless beams subordinate to the base station device. When the communication terminal device moves from within the coverage of a first wireless beam to within the coverage of a second wireless beam, the base station device changes the RRC (Radio Resource Control) parameters used for the communication terminal device from first RRC parameters for the first wireless beam to second RRC parameters for the second wireless beam. In addition, the plurality of wireless beams can be formed by a plurality of DUs (in other words, TRPs) as Figure 8 illustrated, or can be formed by one DU, or can be formed by a base station device integrating a CU and a DU.

[0251] According to this configuration, the RRC parameters used for the communication terminal device are changed according to the change in the wireless beam used for the communication terminal device. Therefore, as described above, the number of communication terminal devices that can be accommodated can be increased.

[0252] Here, the above structure can be variously deformed as described above. For example, the following communication system is provided: that is, the base station device includes at least one DU (Distributed Unit) that outputs a plurality of radio beams and a CU (Central Unit) that controls at least one DU. The CU has a MAC (Medium Access Control) function. The CU notifies the communication terminal device of the second RRC parameter and notifies the communication terminal device of the switching instruction from the first radio beam to the second radio beam using the first radio beam. Alternatively, the following communication system is provided: that is, the base station device has a function of outputting a plurality of radio beams and a MAC function. The base station device notifies the communication terminal device of the second RRC parameter and notifies the communication terminal device of the switching instruction from the first radio beam to the second radio beam using the first radio beam.

[0253] In addition, various deformations are provided as described in the following modification examples 1 to 3.

[0254] Modification example 1 of Embodiment 2.

[0255] In Embodiment 2, the description is centered on the notification of the RRC parameter related to SR, but it can also be applied to the RRC parameter related to Ack / Nack repetition.

[0256] As the RRC parameter related to Ack / Nack repetition in the above, the following (1) to (3) are shown.

[0257] (1) The number of repetitions of Ack / Nack from the UE. For example, repetitionFactor described in Non-Patent Document 12.

[0258] (2) The parameter of the RB that determines the repeated transmission of Ack / Nack. For example, nlPUCCH-AN-Rep described in Non-Patent Document 12.

[0259] (3) The combination of the above (1) and (2).

[0260] According to the above (1), by changing the number of repetitions of Ack / Nack according to the transmission status, especially in a situation where the transmission environment is poor, the reliability of the Ack / Nack notification from the UE to the CU can be improved.

[0261] According to the above (2), by preventing the RB for Ack / Nack repetition from competing with other UEs due to the beam / TRP movement of the UE, the number of UEs accommodated in one beam / TRP can be increased.

[0262] The parameter notified as the above (1) to (3) can be the value itself or the change amount of the value.

[0263] In this Modification Example 1, the method and content of the handover notification notified by the CU to the UE via the pre-movement beam / TRP can be set to be the same as those in Embodiment 2. In addition, the method of notifying the UE of the RRC parameters related to the Ack / Nack repetition via the pre-movement beam / TRP can be applied the same method as the RRC parameter notification described in Embodiment 2.

[0264] The CU may or may not notify the UE of a parameter indicating whether or not the retransmitted data is bundled as an RRC parameter related to the Ack / Nack repetition. The parameter indicating whether or not there is bundling may be, for example, tdd_AckNackFeedbackMode described in Non-Patent Document 12. If the parameter indicating whether or not there is bundling is notified, for example, by invalidating the bundling of retransmission in a poor transmission environment, the CU can suppress the retransmission of user data that has already been confirmed to have been delivered.

[0265] Similar to Embodiment 2, the CU may notify the UE of the parameters required for beam scanning. Thereby, the UE can easily receive the beam scanning signal during the movement between beams / TRPs.

[0266] The notification of the parameters required for beam scanning from the CU to the UE described above may use L1 / L2 signaling or MAC signaling.

[0267] In the notification of the RRC parameters related to the Ack / Nack repetition by the CU to the UE, an identifier indicating the parameter change caused by the TRP / beam handover may be included. The UE may hold the RRC parameters related to the Ack / Nack repetition before the change. Thereby, the UE can prevent the reliability of sending Ack / Nack to the mobile source TRP / beam from being reduced due to the parameter change during the Ack / Nack transmission before the TRP / beam handover.

[0268] Similar to Embodiment 2, regarding the RRC parameters related to the Ack / Nack repetition, the CU may also not notify the parameters using the same values in the mobile target beam / TRP. Therefore, the signaling amount generated by the parameter notification can be reduced.

[0269] The CU and the UE can restore the value of the RRC parameter related to Ack / Nack repetition to its initial value when the beam / TRP of the UE is switched, or can maintain it. The initial value of the RRC parameter can be determined by the standard or can be notified from the CU to the UE using RRC signaling. Whether to restore the value of the parameter at the time of beam / TRP switching of the UE to its initial value or to maintain it can be determined by the standard or can be notified from the CU to the UE in advance. Alternatively, information indicating whether to restore the initial value or to maintain it can be notified from the CU to the UE together with the handover indication. Thus, even when the parameter notification from the mobile source beam / TRP to the UE fails, the UE can use the initial value or the RRC parameter before the change. Therefore, the reliability of the Ack / Nack repetition from the UE to the mobile target beam / TRP can be improved.

[0270] Similar to Embodiment 2, the CU can notify the RRC parameter related to Ack / Nack repetition to the UE together with the handover indication. Thus, the signaling amount during beam / TRP switching can be reduced.

[0271] Alternatively, the CU can notify the handover indication to the UE after notifying the RRC parameter related to Ack / Nack repetition. Thus, the CU can notify the handover indication to the UE after confirming that the RRC parameter related to Ack / Nack repetition has been delivered. As a result, it is possible to avoid the failure of the repeated Ack / Nack from the UE due to the non-delivery of the RRC parameter related to Ack / Nack repetition and the decrease in the reliability of the Ack / Nack notification due to the failure of the repeated Ack / Nack from the UE.

[0272] Alternatively, the CU can notify the RRC parameter related to Ack / Nack repetition to the UE after notifying the handover indication. In this case, the CU can notify the handover indication and the handover timing to the UE together. Thus, even when the processing of switching the communication target beam / TRP in the UE takes time, the handover can be performed smoothly.

[0273] The CU can notify the above-mentioned RRC parameter related to Ack / Nack repetition to the UE using L1 / L2 signaling. Thus, the parameter can be notified to the UE quickly.

[0274] Alternatively, the CU can notify the above-mentioned RRC parameter related to Ack / Nack repetition using MAC signaling. Thus, multi-level modulation can be performed, and the parameter can be notified with a smaller number of symbols. In addition, HARQ retransmission control is performed, so the reliability of the parameter notification is improved. In addition, the CU can notify the handover indication to the UE after confirming that the parameter has been delivered, so it is possible to avoid the failure of the repeated Ack / Nack from the UE due to the non-delivery of the parameter, and the reliability of the Ack / Nack transmission can be improved.

[0275] Regarding the handover notification, similarly to Embodiment 2, the CU can notify the UE using L1 / L2 signaling or can notify the UE using MAC signaling. Thereby, the same effects as those of Embodiment 2 can be obtained.

[0276] As an example of the procedure for notifying RRC parameters related to Ack / Nack repetition and handover indication, it is only necessary to replace the parameter related to SR in step ST902 of Figure 9 with the parameter related to Ack / Nack repetition.

[0277] Similarly to Embodiment 2, the CU can send notifications of parameters related to Ack / Nack repetition to the UE multiple times, increasing the transmission power. Thereby, the reliability of the notification of Ack / Nack repetition can be improved. The same applies to the handover indication from the CU to the UE.

[0278] The UE can notify the mobile target beam / TRP of the Ack / Nack for the downlink user data from the CU received from the mobile source beam / TRP. The above-mentioned notification of Ack / Nack from the UE to the mobile target beam / TRP can be performed when a beam / TRP handover occurs between the downlink user data and the Ack / Nack. Thereby, the downlink user data processing at the time of beam / TRP handover can be smoothly performed in the CU and the UE.

[0279] In the Ack / Nack repetition from the UE to the CU, the CU can use both the Ack / Nack received from the mobile source beam / TRP and the Ack / Nack received from the mobile target beam / TRP, or can use only one of them. The use of Ack / Nack can be performed when switching the beam / TRP during the Ack / Nack repetition from the UE to the CU. Regarding which beam / TRP received Ack / Nack is used above, it can be determined in advance by a standard or can be appropriately switched by the CU. In the above, by using both the Ack / Nack received from the mobile source beam / TRP and the Ack / Nack received from the mobile target beam / TRP, the reliability of the Ack / Nack notification from the UE to the CU can be improved even when switching the beam / TRP during the Ack / Nack repetition. In addition, in the above, by using only one of the Ack / Nack received from the mobile source beam / TRP and the Ack / Nack received from the mobile target beam / TRP, the synthesis process of Ack / Nack repetition in the CU is not required. Thereby, the Ack / Nack reception process in the CU becomes simple.

[0280] The CU can retransmit downlink user data to the UE by using the ACK / NACK repetition sent from the UE to the mobile source beam / TRP via the mobile target beam / TRP. This retransmission can be performed when switching the beam / TRP between the ACK / NACK repetition from the UE to the CU and the retransmission of the downlink user data from the CU to the UE. Thereby, the downlink user data retransmission process can be smoothly performed in the CU and the UE when the beam / TRP switching occurs.

[0281] By using this Modification Example 1, the RRC parameters related to the ACK / NACK repetition can be notified to the UE, and the number of UEs accommodated in the cells spatially separated by the beam / TRP can be increased. In addition, compared with the notification based on the RRC signaling, the parameters can be notified more quickly.

[0282] Modification Example 2 of Embodiment 2.

[0283] In Embodiment 2, the description is centered on the notification of the RRC parameters related to the SR, but it can also be applied to the RRC parameters related to the SRS.

[0284] As the RRC parameters related to the SRS in the above, the following (1) to (7) are shown.

[0285] (1) The band for the SRS. For example, srs-Bandwidth described in Non-Patent Document 12.

[0286] (2) The band for performing SRS frequency hopping. For example, srs-HoppingBandwidth described in Non-Patent Document 12.

[0287] (3) The position on the frequency axis of the SRS. For example, freqDomainPosition described in Non-Patent Document 12.

[0288] (4) The period and subframe offset of the SRS. For example, srs-ConfigIndex described in Non-Patent Document 12.

[0289] (5) The position of the Comb at the time of SRS transmission. For example, transmissionComb described in Non-Patent Document 12.

[0290] (6) The cyclic shift of the SRS. For example, cyclicShift described in Non-Patent Document 12.

[0291] (7) The combination of the above (1) to (6).

[0292] According to the above (1), by changing the band for the SRS according to the number of UEs in the beam / TRP, the number of UEs accommodated in one beam / TRP can be increased.

[0293] According to the above (2), by flexibly changing the frequency band for SRS hopping according to the number of UEs within a beam / TRP, the number of UEs that can be accommodated in one beam / TRP can be increased.

[0294] According to the above (3), by preventing the position of the SRS on the frequency axis from competing with other UEs due to the movement of the UE between beams / TRPs, the number of UEs that can be accommodated in one beam / TRP can be increased.

[0295] According to the above (4), by preventing the SRS transmission timing from competing with other UEs due to the movement of the UE between beams / TRPs, the number of UEs that can be accommodated in one beam / TRP can be increased.

[0296] According to the above (5), by preventing the position of the SRS Comb from competing with other UEs due to the movement of the UE between beams / TRPs, the number of UEs that can be accommodated in one beam / TRP can be increased.

[0297] According to the above (6), by preventing the cyclic shift amount of the SRS from competing with other UEs due to the movement of the UE between beams / TRPs, the number of UEs that can be accommodated in one beam / TRP can be increased.

[0298] In the above (4), only the subframe offset of the SRS transmission can be changed. In addition, when the subframe offset is changed, only the information of the subframe offset can be notified. Thus, for the SRS transmissions of multiple UEs in the mobile target beam / TRP, it can be easily adjusted by the CU to avoid competition between UEs. In addition, according to only notifying the information of the subframe offset, the amount of bits transmitted from the CU to the UE can be reduced.

[0299] The parameter notified as the above (1) to (7) can be the value itself or the change amount of the value. By using the value itself, the process of parameter notification from the CU to the UE becomes easy. In addition, by using the change amount of the value, the number of bits required for parameter notification can be reduced.

[0300] In this Modification 2, the method and content of the handover notification notified by the CU to the UE via the pre-movement beam / TRP can be set to be the same as those in Embodiment 2. In addition, the notification method of the RRC parameters related to the SRS notified by the CU to the UE via the pre-movement beam / TRP can be applied to the same method as the notification of the RRC parameters described in Embodiment 2.

[0301] The CU can notify the UE of a parameter indicating whether there is continuous SRS transmission as an RRC parameter related to the SRS, or it can also not notify. The parameter indicating whether there is continuous transmission can be, for example, Duration described in Non-Patent Document 12. By notifying the above parameter, the CU can flexibly allocate the SRS resources to the UE.

[0302] Similar to Embodiment 2, the CU can notify the UE of the parameters required for beam scanning. Thus, the UE can easily receive the beam scanning signal during the movement between beams / TRPs.

[0303] For the above notification of the parameters required for beam scanning from the CU to the UE, L1 / L2 signaling or MAC signaling can be used.

[0304] In the notification of the RRC parameters related to SRS by the CU to the UE, an identifier indicating the parameter switch caused by the TRP / beam switch can be included. The UE can maintain the RRC parameters related to SRS before the change. Thus, in the SRS transmission before the TRP / beam switch, the UE can prevent the random access action and the decrease in the uplink communication rate caused by the failure of the SRS to reach the CU due to the parameter change.

[0305] Similar to Embodiment 2, regarding the RRC parameters related to SRS, the CU may also not notify the parameters with the same value for use in the moving target beam / TRP. Therefore, the signaling amount generated by the parameter notification can be reduced.

[0306] The CU and the UE can restore the value of the RRC parameters related to SRS to the initial value or maintain it when the beam / TRP of the UE is switched. The initial value of the RRC parameters can be determined by the standard or notified from the CU to the UE using RRC signaling. Whether to restore the value of the parameters at the beam / TRP switch of the UE to the initial value or maintain it can be determined by the standard or notified in advance from the CU to the UE. Alternatively, the information on whether to restore the initial value or maintain it can be notified from the CU to the UE together with the handover indication.

[0307] Thus, even when the parameter notification from the mobile source beam / TRP to the UE fails, the UE can prevent the situation where the SRS from the UE does not reach the mobile target beam / TRP by using the initial value or the RRC parameters before the change.

[0308] Similar to Embodiment 2, the CU can notify the UE of the RRC parameters related to SRS together with the handover indication. Thus, the signaling amount during the beam / TRP switch can be reduced.

[0309] Alternatively, the CU can notify the handover indication to the UE after the notification of the RRC parameters related to SRS. Thus, the CU can notify the handover indication to the UE after confirming the delivery of the RRC parameters related to SRS. As a result, the situation where the SRS from the UE does not reach the CU due to the non-delivery of the RRC parameters related to SRS can be avoided, and the decrease in the uplink communication rate and the occurrence of random access can be avoided.

[0310] Alternatively, after notifying the handover indication, the CU may notify the UE of the RRC parameters related to the SRS. In this case, the CU may notify the UE of the handover indication together with the handover timing. Thus, even if it takes time for the UE to process the beam / TRP for switching the communication target, the handover can be performed smoothly.

[0311] The CU may notify the UE of the above-mentioned RRC parameters related to the SRS by using L1 / L2 signaling. Thus, the parameters can be notified to the UE quickly.

[0312] Alternatively, the CU may notify the above-mentioned RRC parameters related to the SRS by using MAC signaling. Thus, multi-level modulation can be performed, and the parameters can be notified with a smaller number of symbols. In addition, HARQ retransmission control is performed, so the reliability of parameter notification is improved. Since the CU can notify the handover indication to the UE after confirming that the parameters have been delivered, it is possible to avoid the non-delivery of the SRS from the UE to the CU due to the non-delivery of the parameters, and to avoid a decrease in the uplink communication rate and the occurrence of random access.

[0313] Regarding the handover notification, similarly to Embodiment 2, it may be notified from the CU to the UE by using L1 / L2 signaling, or it may be notified from the CU to the UE by using MAC signaling. Thus, the same effects as those of Embodiment 2 can be obtained.

[0314] As an example of the procedure for notifying the RRC parameters related to the SRS and the handover indication, Figure 9 replace the SR-related parameters in step ST902 with the SRS-related parameters.

[0315] Similarly to Embodiment 2, the CU may send multiple notifications of the SRS-related parameters to the UE to increase the transmission power. Thus, the reliability of the SRS-related parameter notification can be improved. The same applies to the handover indication from the CU to the UE.

[0316] The UE may perform SRS transmission in response to the SRS transmission indication from the CU received from the mobile source beam / TRP by using the mobile target beam / TRP. The above-mentioned SRS transmission from the UE to the mobile target beam / TRP may be performed when a beam / TRP handover occurs between the SRS transmission indication and the SRS transmission. The above-mentioned SRS transmission may be an aperiodic SRS transmission. Thus, the SRS transmission processing can be smoothly performed in the CU and the UE when a beam / TRP handover occurs.

[0317] The CU can invalidate the SRS sent from the UE to the mobile source beam. The action of invalidating the SRS can be performed when the beam / TRP is switched after the SRS is sent. The CU can retransmit the SRS transmission indication to the UE. The UE can retransmit the SRS to the mobile target beam / TRP. Thus, the CU can perform scheduling adapted to the transmission status after the beam / TRP is switched.

[0318] The above SRS retransmission from the UE can be performed autonomously by the UE. Thus, the CU can quickly obtain the SRS after the beam / TRP is switched. In the above, whether the UE autonomously retransmits the SRS can be determined by the standard, and can be notified to the UE in advance from the CU through RRC signaling, or notified together with the handover indication notification from the CU to the UE.

[0319] By using this Modification Example 2, the RRC parameters related to the SRS can be notified to the UE, and the number of UEs accommodated in the cells spatially separated by the beam / TRP can be increased. In addition, compared with the notification based on RRC signaling, the parameters can be notified quickly.

[0320] Modification Example 3 of Embodiment 2.

[0321] In Embodiment 2, the description is centered on the notification of the RRC parameters related to the SR, but it can also be applied to the RRC parameters related to the CQI / CSI.

[0322] As the RRC parameters related to the CQI / CSI in the above, the following (1) to (5) are shown.

[0323] (1) Parameters of the RB that determines the CQI. For example, cqi-PUCCH-Resourcelndex described in Non-Patent Document 12.

[0324] (2) Period and subframe offset of the CQI and PMI (Precoding Matrix Indicator). For example, cqi-pmi-Configindex described in Non-Patent Document 12.

[0325] (3) Period and subframe offset of the RI (Rank Indicator). For example, ri-ConfigIndex described in Non-Patent Document 12.

[0326] (4) Whether Ack / Nack and CQI can be transmitted simultaneously. For example, simultaneousAckNackAndCQI described in Non-Patent Document 12.

[0327] (5) Combinations of the above (1) to (4).

[0328] According to (1) above, by preventing the positions of the RBs for CQI from competing with other UEs due to the beam / TRP - to - beam / TRP movement of the UE, the number of UEs that can be accommodated in one beam / TRP can be increased.

[0329] According to (2) above, by preventing the CQI and PMI transmission timings from competing with other UEs due to the beam / TRP - to - beam / TRP movement of the UE, the number of UEs that can be accommodated in one beam / TRP can be increased.

[0330] According to (3) above, by preventing the RI transmission timing from competing with other UEs due to the beam / TRP - to - beam / TRP movement of the UE, the number of UEs that can be accommodated in one beam / TRP can be increased.

[0331] According to (4) above, based on the situation of uplink data scheduling during the beam / TRP - to - beam / TRP movement of the mobile target, it is possible to flexibly set whether to simultaneously transmit Ack / Nack and CQI, so that the UE can efficiently transmit Ack / Nack and CQI to the CU.

[0332] In (2) above, only the sub - frame offsets of CQI and PMI can be changed. In addition, when the sub - frame offset is changed, only the information of the sub - frame offset can be notified. Thus, for the CQI / CSI transmission of multiple UEs in the mobile target beam / TRP, it is easy for the CU to make adjustments to avoid competition among UEs. In addition, according to only notifying the information of the sub - frame offset, the amount of bits transmitted from the CU to the UE can be reduced.

[0333] In (3) above, only the sub - frame offset of RI can be changed in the same way as in (2). In addition, when the sub - frame offset is changed, only the information of the sub - frame offset can be notified. Thus, the same effect as above can be obtained.

[0334] The parameters notified as (1) - (5) above can be the value itself or the amount of change of the value. By using the value itself, the process of parameter notification from the CU to the UE becomes easy. In addition, by using the amount of change of the value, the number of bits required for parameter notification can be reduced.

[0335] Similar to Embodiment 2, the CU can notify the UE of the parameters required for beam scanning. Thus, the UE can easily receive the beam scanning signal during the beam / TRP - to - beam / TRP movement.

[0336] The notification of the parameters required for beam scanning from the CU to the UE above can use L1 / L2 signaling or MAC signaling.

[0337] In this third modification example, the method and content of the handover notification notified by the CU to the UE via the pre-movement beam / TRP can be set to be the same as those in Embodiment 2. In addition, the method of notifying the UE of the RRC parameters related to CQI / CSI via the pre-movement beam / TRP can be applied using the same method as the notification of the RRC parameters described in Embodiment 2.

[0338] In the notification of the RRC parameters related to CQI / CSI from the CU to the UE, an identifier indicating the parameter switch caused by the TRP / beam handover can be included. The UE can maintain the RRC parameters related to CQI / CSI before the change. Thereby, in the transmission of CQI / CSI before the TRP / beam handover, the UE can prevent the downlink communication rate from decreasing due to the failure of CQI / CSI to reach the CU caused by parameter changes.

[0339] Similar to Embodiment 2, regarding the RRC parameters related to CQI / CSI, the CU may not notify the parameters that use the same value even in the target beam / TRP of movement. Therefore, the signaling amount generated by parameter notification can be reduced.

[0340] The CU and the UE can restore the value of the RRC parameters related to CQI / CSI to the initial value or maintain it when the beam / TRP of the UE is switched. The initial value of the RRC parameters can be determined by the standard or notified from the CU to the UE using RRC signaling. Whether to restore the value of the parameters at the time of beam / TRP switching of the UE to the initial value or maintain it can be determined by the standard or notified from the CU to the UE in advance. Alternatively, the information indicating whether to restore the initial value or maintain it can be notified from the CU to the UE together with the handover indication. Thereby, even when the parameter notification from the source beam / TRP to the UE fails, the UE can use the initial value or the RRC parameters before the change. Therefore, for example, when the same RRC parameters as those of the source beam / TRP are used in the target beam / TRP of movement, the UE can prevent CQI / CSI from not reaching the target beam / TRP of movement.

[0341] Similar to Embodiment 2, the CU can notify the UE of the RRC parameters related to CQI / CSI together with the handover indication. Thereby, the signaling amount in the beam / TRP handover can be reduced.

[0342] Alternatively, the CU can notify the UE of the handover indication after notifying the RRC parameters related to CQI / CSI. Thereby, the CU can notify the UE of the handover indication after confirming that the RRC parameters related to CQI / CSI have been delivered. As a result, it is possible to avoid the failure of CQI from the UE to the CU caused by the non-delivery of the RRC parameters related to CQI / CSI, and to avoid the decrease in the downlink communication rate.

[0343] Alternatively, after notifying the handover indication, the CU may notify the UE of RRC parameters related to CQI / CSI. In this case, the CU may notify the handover indication and the handover timing to the UE together. Thus, even if it takes time for the UE to process the beam / TRP for switching the communication target, the handover can be smoothly performed.

[0344] The CU may notify the above-mentioned RRC parameters related to CQI / CSI to the UE by using L1 / L2 signaling. Thus, the parameters can be quickly notified to the UE.

[0345] Alternatively, the CU may notify the above-mentioned RRC parameters related to CQI / CSI by using MAC signaling. Thus, multi-level modulation can be performed, and the parameters can be notified with a smaller number of symbols. In addition, HARQ retransmission control is performed, so the reliability of parameter notification is improved. Since the CU can notify the handover indication to the UE after the parameter confirmation is delivered, it is possible to avoid the non-delivery of CQI / CSI from the UE to the CU due to the non-delivery of the parameters, and it is possible to avoid the decrease in the downlink communication rate.

[0346] Regarding the handover notification, similarly to Embodiment 2, it may be notified from the CU to the UE by using L1 / L2 signaling, or it may be notified from the CU to the UE by using MAC signaling. Thus, the same effect as in Embodiment 2 can be obtained.

[0347] As an example of the procedure for notifying RRC parameters related to CQI / CSI and the handover indication, replace the parameter related to SR in step ST902 of Figure 9 with the parameter related to CQI / CSI.

[0348] Similarly to Embodiment 2, the CU may send the notification of the parameters related to CQI / CSI to the UE multiple times to increase the transmission power. Thus, the reliability of the notification of the parameters related to CQI / CSI can be improved. The same applies to the handover indication from the CU to the UE.

[0349] The UE may perform CQI / CSI transmission in response to the CQI / CSI transmission indication received from the CU from the mobile source beam / TRP by using the mobile target beam / TRP. The above CQI / CSI transmission from the UE to the mobile target beam / TRP may be performed when a beam / TRP handover occurs between the CQI / CSI transmission indication and the CQI / CSI transmission. The above CQI / CSI transmission may be an aperiodic CQI / CSI transmission. Thus, the CQI / CSI transmission processing at the time of beam / TRP handover can be smoothly performed in the CU and the UE.

[0350] The CU can invalidate the CQI / CSI sent from the UE to the mobile source beam. The action of invalidating the CQI / CSI can be performed when the beam / TRP is switched after the CQI / CSI is sent. The CU can retransmit the CQI / CSI transmission indication to the UE. The UE can retransmit the CQI / CSI to the mobile target beam / TRP. Thus, the CU can perform scheduling adapted to the transmission status after the beam / TRP is switched.

[0351] The above retransmission of the CQI / CSI from the UE can be performed independently by the UE. Thus, the CU can quickly obtain the CQI / CSI after the beam / TRP is switched. In the above, whether the UE retransmits the CQI / CSI independently can be determined by the standard, and can be notified to the UE in advance from the CU through the CQI / CSI signaling, or notified together with the handover indication notification from the CU to the UE.

[0352] By using this Modification 3, the RRC parameters related to the CQI / CSI can be notified to the UE, and the number of UEs accommodated in the cells spatially separated by the beam / TRP can be increased. In addition, compared with the notification based on the RRC signaling, the parameters can be notified quickly.

[0353] Embodiment 3.

[0354] In Embodiment 2, the case where the gNB notifies the RRC parameters from the mobile source beam / TRP to the UE is shown. In NR, in order to ensure a wideband, frequencies higher than those in LTE are studied. When using high frequencies, there are cases where the communication status deteriorates sharply due to the influence of obstacles and the like. At this time, when the beam / TRP is switched, if the RRC parameter notification or the handover notification cannot be performed in time, there will be a problem of radio link loss between the gNB and the UE.

[0355] This Embodiment 3 discloses a method for solving the above problems.

[0356] The CU notifies the RRC parameters to the UE via the mobile target beam / TRP. The handover indication notification from the CU to the UE is performed via the mobile source beam / TRP. The fact that the RRC parameter notification from the CU is performed via the mobile target beam / TRP is different from Embodiment 2.

[0357] The notification of the RRC parameters from the CU to the UE can be performed after the handover notification from the CU to the UE. Thus, the UE can smoothly obtain the above RRC parameters after switching the communication target beam / TRP.

[0358] The RRC parameters can be the parameters shown in Section 6.3.2 of Non-Patent Document 12 in the same manner as in Embodiment 2. The RRC parameters can be, for example, parameters related to SR, parameters related to Ack / Nack repetition, parameters related to the Sounding Reference Signal (SRS), or parameters related to CQI / CSI.

[0359] The CU can notify the UE of the parameters required for beam scanning. The parameters required for beam scanning can be set as the parameters shown in Embodiment 1. The notification of the parameters required for beam scanning can be performed via the mobile source beam / TRP. The parameters required for beam scanning can be set as the parameters in the mobile target beam / TRP. Thereby, the UE can easily receive the beam scanning signal during the movement between beams / TRPs.

[0360] In the above, the notification of the parameters required for beam scanning from the CU to the UE can use L1 / L2 signaling in the same manner as in Embodiment 2, or can use MAC signaling. Thereby, the parameters required for beam scanning can be notified quickly.

[0361] The RRC parameters related to SR in the above can be the parameters shown in (1) to (3) in Embodiment 2. In addition, in the same manner as in Embodiment 2, the CU can notify the UE of the parameter indicating the maximum number of retransmissions of SR as the RRC parameter related to SR, or can not notify. Thereby, the same effect as in Embodiment 2 can be obtained.

[0362] The notification of the RRC parameters from the CU to the UE can use L1 / L2 signaling in the same manner as in Embodiment 2. Thereby, the CU can quickly notify the UE. In addition, even when the frequency resource for the Ack / Nack response from the UE to the CU changes due to the handover of the beam / TRP of the gNB, the above RRC parameters can be notified from the CU to the UE.

[0363] Alternatively, MAC signaling can be used in the above. Thereby, in the same manner as in Embodiment 2, the above RRC parameters can be transmitted with a smaller number of symbols, and the reliability of parameter notification is improved. Therefore, it is possible to avoid, for example, the non-delivery of SR from the UE due to the non-delivery of the above parameters and the execution of random access due to exceeding the number of retransmissions.

[0364] Alternatively, RRC signaling can be used in the above. Thereby, the RRC parameters can be notified from the CU to the UE in advance, so there is no need to notify the RRC parameters during beam / TRP handover. Thereby, the signaling amount can be reduced. In terms of notifying the RRC parameters from the mobile target beam / TRP to the UE, the above method is different from Non-Patent Document 1.

[0365] For the method of notifying the handover indication from the CU to the UE, L1 / L2 signaling can be used in the same way as in Embodiment 2. Alternatively, MAC signaling can be used. Thus, the UE can be notified of the beam / TRP handover quickly. In addition, by using MAC signaling, the reliability of the above notification can be improved.

[0366] Regarding the RRC parameters, the CU may also not notify the parameters that use the same values even in the mobile target beam / TRP. Therefore, the signaling volume generated by parameter notification can be reduced.

[0367] Similar to Embodiment 2, when the beam / TRP of the UE is switched, the CU and the UE can restore the value of the RRC parameter to the initial value, or can maintain the value of the parameter. The maintenance of the parameter value can be performed, for example, when the parameter notification from the CU to the UE fails. The initial value of the parameter value can be determined by the standard, or can be notified from the CU to the UE in advance using RRC signaling. Whether to restore the parameter value to the initial value or maintain it when the beam / TRP of the UE is switched can be set by the standard, can be notified from the CU to the UE in advance, or can be notified from the CU together with the handover indication. Thus, even when the parameter notification from the mobile source beam / TRP to the UE fails, the UE can use the RRC parameter before the change. Therefore, for example, when the same RRC parameter is used in the mobile target beam / TRP as in the mobile source beam / TRP, the UE can prevent the situation where the SR is not delivered to the mobile target beam / TRP.

[0368] Similar to Embodiment 2, the gNB can switch the beam / TRP when the handover indication from the mobile source beam / TRP to the UE exceeds the HARQ retransmission count, or can not switch the beam / TRP. For various situations, the same effects as in Embodiment 2 can be obtained.

[0369] Figure 10 It is a flowchart showing the beam / TRP handover when notifying parameters from the CU via the mobile target beam / TRP. Figure 10 An example of notifying parameters and handover indication from the CU to the UE using MAC signaling is shown. Figure 10 In this, the mobile source beam / TRP under the CU is denoted as S-beam / TRP, and the mobile target beam / TRP under the CU is denoted as T-beam / TRP. In addition, Figure 10 In this, the black circle in the arrow indicates the beam / TRP used for communication. The same step numbers are assigned to the same steps as in Figure 9 and the common description is omitted.

[0370] Figure 10 In this, before the beam / TRP handover, the UE transmits and receives user data with the CU via the S-beam / TRP (step ST901).

[0371] Figure 10 In step ST2001, the CU notifies the UE of a handover indication via the S-beam / TRP. The handover indication can be notified using MAC signaling or L1 / L2 signaling. The CU may include information indicating the T-beam / TRP in the handover indication. In step ST2002, the UE notifies the CU of an Ack for the handover indication via the S-beam / TRP. In the case where the reception result from the UE is Nack, the CU may retransmit the handover indication via the S-beam / TRP.

[0372] Figure 10 In step ST2003, the CU notifies the UE of SR parameters via the T-beam / TRP. MAC signaling is used for this notification, or L1 / L2 signaling may also be used. In addition, the SR parameters may include the sr-PUCCH-ResourceIndex shown in Non-Patent Document 12, or may include the sr-ConfigIndex shown in Non-Patent Document 12. In step ST2004, the UE notifies the CU of an Ack for the notification of the SR parameters via the T-beam / TRP. In the case where the reception result from the UE is Nack, the CU may retransmit the SR parameters via the T-beam / TRP.

[0373] The UE may transmit an uplink signal to the beam / TRP of the mobile source. The uplink signal may be a response to the L1 / L2 signaling for the handover indication from the CU. As the uplink signal, L1 / L2 signaling for response may be newly set. As the above response, new uplink control information (UCI) may be set. Thus, even when L1 / L2 signaling is used in the handover indication from the CU, the CU can perform delivery confirmation to the UE. Thus, the reliability of the above L1 / L2 signaling can be improved.

[0374] For the new UCI, it may be set the same as in Embodiment 2. Thus, the same effect as in Embodiment 2 can be obtained.

[0375] Alternatively, the UE may transmit an uplink signal to the beam / TRP of the mobile target. The CU and the UE may use the uplink signal as a confirmation signal for beam / TRP switching in the UE. The uplink signal may be a response to the MAC signaling for the RRC parameter notification from the CU, or may be a response to the L1 / L2 signaling for the RRC parameter notification from the CU. As the uplink signal, L1 / L2 signaling for response may be newly set. As the above response, new uplink control information (UCI) may be set. Thus, even when L1 / L2 signaling is used in the handover indication from the CU, the CU can perform delivery confirmation to the UE. Thus, the reliability of the above L1 / L2 signaling can be improved.

[0376] Similar to Embodiment 2, the CU can notify the UE whether there is a request to send an uplink signal to the UE. The presence or absence of this request can be separately for the uplink signal to the mobile source beam / TRP and the uplink signal to the mobile target beam / TRP. The presence or absence of this request can be included in the handover indication from the CU to the UE. Thus, for example, when the communication quality is excellent, a response from the UE is not required, so the signaling amount can be reduced.

[0377] The UE can use the frequency resources of the SR to send the above-mentioned confirmation signal. Or, the SR can be sent as the above-mentioned confirmation signal. Thus, the frequency resources for the uplink signal can be saved.

[0378] Similar to Embodiment 2, the UE can send the above-mentioned SR at the minimum period. Thus, it is possible to confirm at low latency the case where the UE has switched the communication target beam / TRP.

[0379] Similar to Embodiment 2, the CU can ensure the SR shared resource shared by the UEs existing within the coverage of the same beam / TRP. The UE can use the SR shared resource to send the SR. The SR shared resource can be a resource that allows UEs to compete with each other (contention-based). Thus, even when the RRC parameter reception fails, the UE can notify the CU that the beam / TRP handover has been performed.

[0380] The CU and the UE can set the initial value of the RRC parameter related to the SR to the position of the SR shared resource when the beam / TRP of the UE is switched. The UE can use the SR shared resource to notify the SR to the mobile target beam / TRP. Thus, the UE can send the SR to the CU immediately after the communication target beam / TRP is switched. Therefore, the uplink user data can be sent to the CU immediately after the communication target beam / TRP is switched. Thus, the delay of the uplink communication during the beam / TRP handover can be reduced.

[0381] Similar to Embodiment 2, the UE can send the SRS to the mobile target beam / TRP. The SRS can be aperiodic or periodic. The UE can send the SRS to the mobile target beam / TRP a predetermined number of times. This number of transmissions can be determined by the standard or can be notified to the UE by the CU in advance. Thus, even when there is no uplink user data sent to the CU, the UE can notify the CU that the communication target beam / TRP has been switched.

[0382] Similarly to Embodiment 2, the CU can use the above SR to determine whether there is a communication target beam / TRP handover in the UE. The CU can re-notify the parameters related to the SR and the handover indication from the mobile source beam / TRP. Thereby, it is possible to prevent RLF or random access caused by the UE failing to receive the parameters or handover indication related to the SR. Thereby, the time for beam / TRP handover can be shortened.

[0383] Similarly to Embodiment 2, the CU can notify the UE of the parameters multiple times. In addition, the CU can increase the transmission power for notifying the UE of the parameters. Thereby, the reliability of parameter notification can be improved.

[0384] For the SR transmission from the UE, the CU can invalidate the SR received by the mobile source beam / TRP. When a beam / TRP handover occurs between SR reception and uplink scheduling grant transmission, the CU can invalidate the SR. In the above, the UE can retransmit the SR to the mobile target beam / TRP. The retransmission of the SR can be performed after receiving the RRC parameter notification from the CU to the UE. Thereby, it is possible to prevent the retransmitted SR from the UE from not reaching the CU.

[0385] Alternatively, similarly to Embodiment 2, regarding the beam / TRP handover after the SR transmission from the UE, the CU can make the SR received by the mobile source beam / TRP valid. Thereby, it is possible to smoothly perform the uplink data communication when the beam / TRP handover occurs.

[0386] Regarding the uplink scheduling grant notification from the CU to the UE, similarly to Embodiment 2, the CU and the UE invalidate the uplink scheduling grant when a beam / TRP handover occurs between the uplink scheduling grant and the uplink user data. In the above, the CU can retransmit the uplink scheduling grant from the mobile target beam / TRP. Alternatively, the UE can restart the SR transmission to the mobile target beam / TRP. The retransmission of the SR can be performed after receiving the RRC parameter notification from the CU to the UE. Thereby, it is possible to prevent the situation where the retransmitted SR from the UE does not reach the CU.

[0387] In the above, the CU and the UE can make the above grant valid. The actions of the CU and the UE when making the grant valid are the same as those in Embodiment 2. Thereby, the signaling amount between the CU and the UE can be reduced.

[0388] It can be determined by a standard whether the above-mentioned uplink scheduling grant is made valid, or it can be notified from the CU to the UE. The notification from the gNB to the UE can be preformed by RRC signaling, by MAC signaling, or by L1 / L2 signaling. As an example of the case where the uplink scheduling grant is made valid, it can be set to the case where the mobile target beam / TRP can use the uplink resources indicated by the scheduling grant for this UE. In an example where the above-mentioned notification is performed by MAC signaling or L1 / L2 signaling, the above-mentioned notification can be performed together with the handover notification. Thereby, the CU can perform scheduling corresponding to the uplink resource usage status in the mobile target beam / TRP with less signaling.

[0389] For the uplink user data transmission from the UE to the CU, the CU can send an Ack / Nack for the uplink user data received from the UE using the mobile source beam / TRP to the UE from the mobile target beam / TRP. The above-mentioned Ack / Nack transmission from the mobile target beam / TRP can be performed when a beam / TRP handover occurs between the uplink user data transmission from the UE and the Ack / Nack notification from the gNB. The Ack / Nack notification from the UE can be performed before the RRC parameter notification from the CU to the UE, or after the RRC parameter notification from the CU to the UE. Alternatively, the Ack / Nack notification can be performed between the above-mentioned parameter notification and the Ack / Nack response from the UE to the CU for the above-mentioned parameter notification. Thereby, the beam / TRP handover after the uplink user data transmission can be smoothly performed.

[0390] According to the third embodiment, in addition to the effects shown in the second embodiment, when the communication environment between the mobile source beam / TRP and the UE deteriorates rapidly, the CU can also notify the UE of the RRC parameters. As a result, for example, the random access process of the UE caused by the non-delivery of the SR can be suppressed.

[0391] The second embodiment and the third embodiment can be combined. That is, the CU can switch which of the mobile source beam / TRP and the mobile target beam / TRP to send the RRC parameters from. Thereby, the CU can flexibly change the beam / TRP for sending the RRC parameters according to the communication environment.

[0392] Regarding which of the mobile source beam / TRP and the mobile target beam / TRP to send the RRC parameters from, the CU can be set quasi-statically in advance to the UE. RRC signaling can be used in this notification. Thereby, the notification path of the RRC parameters can be flexibly set according to the transmission status.

[0393] Alternatively, it can be dynamically set by the CU. For example, the CU can include in the handover indication information indicating which of the mobile source beam / TRP and the mobile target beam / TRP to transmit the RRC parameters to notify the UE. The UE can use this notification to receive the RRC parameters. Thus, since the UE can clearly know the reception target of the RRC parameters, the reliability of obtaining the RRC parameter notification can be improved.

[0394] Alternatively, it can be implicitly determined by the standard. For example, the UE can receive the RRC parameters through the mobile source beam / TRP before receiving the handover indication, or can receive the RRC parameters through the mobile target beam / TRP after receiving the handover indication. Thus, there is no need to notify the UE from the CU of the information indicating which of the mobile source beam / TRP and the mobile target beam / TRP to receive the RRC parameters.

[0395] In Embodiment 3, a base station device with separated CU and DU is taken as an example, but it can also be applied to a base station device with non-separated CU and DU. This base station device can be a base station device that does not share RRC parameters between beams. When applying Embodiment 3 to this base station device, the CU can be replaced by the gNB. Thus, during the movement between beams within the cell, the RRC parameters can be notified to the UE from the gNB via the mobile target beam, and the number of UEs accommodated in the cell spatially separated by the beams can be increased. The parameters can be quickly notified from the gNB to the UE.

[0396] According to Embodiment 3, similar to Embodiment 2, the following communication system is provided. This communication system includes, for example, a communication terminal device and a base station device that performs wireless communication with the communication terminal device using wireless beams. The cell formed by the base station device is spatially separated by a plurality of wireless beams under the base station device. When the communication terminal device moves from the coverage range of the first wireless beam to the coverage range of the second wireless beam, the base station device changes the RRC (Radio Resource Control) parameters used for the communication terminal device from the first RRC parameters for the first wireless beam to the second RRC parameters for the second wireless beam. In addition, the plurality of wireless beams can be formed by a plurality of DUs (in other words, TRPs) as Figure 8 illustrated, or can be formed by one DU, or can be formed by a base station device integrating the CU and the DU.

[0397] According to this structure, the RRC parameters used for the communication terminal device are changed according to the change of the wireless beam used for the communication terminal device. Therefore, as described above, the number of communication terminal devices that can be accommodated can be increased.

[0398] Here, the above structure can be deformed in various ways as described above. In particular, according to Embodiment 3, for example, a communication system is provided as follows: that is, a base station device includes at least one DU (Distributed Unit) that outputs a plurality of radio beams and a CU (Central Unit) that controls at least one DU. The CU has a MAC (Medium Access Control) function. The CU notifies a communication terminal device of second RRC parameters using a second radio beam and notifies the communication terminal device of a handover instruction from the first radio beam to the second radio beam using the first radio beam. Alternatively, a communication system is provided as follows: that is, a base station device has a function of outputting a plurality of radio beams and a MAC function. The base station device notifies a communication terminal device of second RRC parameters using a second radio beam and notifies the communication terminal device of a handover instruction from the first radio beam to the second radio beam using the first radio beam.

[0399] In addition, various deformations are provided as described in the following Modification Examples 1 to 3.

[0400] Modification Example 1 of Embodiment 3.

[0401] In Embodiment 3, the description is centered on the notification of RRC parameters related to SR, but it can also be applied to RRC parameters related to Ack / Nack repetition.

[0402] The above RRC parameters related to Ack / Nack repetition can be the same as those in Modification Example 1 of Embodiment 2.

[0403] In this Modification Example 1, the method and content of the handover notification notified by the CU to the UE via the pre-movement beam / TRP can be set to be the same as those in Embodiment 3. In addition, the method of notifying the RRC parameter notification related to Ack / Nack repetition from the CU to the UE via the movement target beam / TRP can be applied to the same method as the RRC parameter notification described in Embodiment 3. Thereby, the UE can smoothly obtain the above RRC parameters after switching the communication target beam / TRP.

[0404] Similar to Embodiment 3, the CU can notify the UE of the parameters required for beam scanning. The method of notifying the parameters can be the same as that in Embodiment 3. Thereby, the UE can easily receive the beam scanning signal during the movement between beams / TRPs.

[0405] The notification of the parameters required for beam scanning from the CU to the UE described above can use L1 / L2 signaling or MAC signaling. Thereby, the same effect as in Embodiment 3 can be obtained.

[0406] Similar to Embodiment 3, regarding the RRC parameters related to Ack / Nack repetition, the CU may also not notify the parameters that use the same values in the mobile target beam / TRP. Therefore, the signaling volume generated by parameter notification can be reduced.

[0407] Similar to Embodiment 3, the CU and the UE may restore the value of the RRC parameter related to Ack / Nack repetition to the initial value or keep it when the beam / TRP of the UE is switched. Whether to restore the parameter value to the initial value or keep it when the beam / TRP of the UE is switched can be determined by the standard or notified from the CU to the UE in advance. Alternatively, the information on whether to restore to the initial value or keep it can be notified from the CU to the UE together with the handover indication. Thus, the same effect as Embodiment 3 can be obtained.

[0408] The CU can notify the UE of the above-mentioned RRC parameters related to Ack / Nack repetition by using L1 / L2 signaling. Thus, the parameters can be notified to the UE quickly.

[0409] Alternatively, the CU can notify the above-mentioned RRC parameters related to Ack / Nack repetition by using MAC signaling. Thus, multi-level modulation can be performed, and the parameters can be notified with fewer symbols. In addition, HARQ retransmission control is performed, so the reliability of parameter notification is improved.

[0410] Regarding the handover notification, similar to Embodiment 3, it can be notified from the CU to the UE by using L1 / L2 signaling or by using MAC signaling. Thus, the same effect as Embodiment 3 can be obtained.

[0411] As an example of the process of RRC parameter notification and handover indication related to Ack / Nack repetition, replace the parameter related to SR in step ST2003 of Figure 10 with the parameter related to Ack / Nack repetition.

[0412] Similar to Embodiment 3, the CU can send multiple notifications of the parameters related to Ack / Nack repetition to the UE, increasing the transmission power. Thus, the reliability of the notification of Ack / Nack repetition can be improved. The same applies to the handover indication from the CU to the UE.

[0413] The UE can notify the mobile target beam / TRP of the Ack / Nack for the downlink user data from the CU received from the mobile source beam / TRP. The above-mentioned notification of Ack / Nack from the UE to the mobile target beam / TRP can be performed when there is a beam / TRP switch between the downlink user data and the Ack / Nack. Thus, the downlink user data processing can be smoothly performed in the CU and the UE when a beam / TRP switch occurs.

[0414] The above-mentioned notification of Ack / Nack from the UE to the mobile target beam / TRP can be performed after receiving the parameter notification related to Ack / Nack repetition from the CU to the UE. Thus, the CU can receive the subsequent Ack / Nacks set by Ack / Nack repetition, and therefore the reliability of the Ack / Nack notification from the UE to the CU can be improved.

[0415] In the Ack / Nack repetition from the UE to the CU, the CU can use only the Ack / Nack received from the mobile source beam / TRP. The utilization of the Ack / Nack can be performed when switching the beam / TRP during the Ack / Nack repetition from the UE to the CU. Thus, when switching the beam / TRP during the Ack / Nack repetition, the Ack / Nack reception processing in the CU can be smoothly performed.

[0416] Alternatively, in the Ack / Nack repetition from the UE to the CU, the CU can make the Ack / Nacks received from both the mobile source beam / TRP and the mobile target beam / TRP valid. In the above, the UE can send the Ack / Nack repetition to the mobile target beam / TRP after receiving the RRC parameter related to the Ack / Nack repetition. Thus, the reliability of the Ack / Nack notification from the UE to the CU can be improved.

[0417] Regarding whether the CU uses the Ack / Nack received through the mobile target beam / TRP in the above, it can be determined in advance by the standard or can be appropriately switched by the CU. Thus, for example, the switching can be flexibly performed according to the transmission environment, and the Ack / Nack can be efficiently received.

[0418] Regarding whether the CU uses the Ack / Nack received through the mobile target beam / TRP in the above, it can be notified by the CU to the UE. This notification can use RRC signaling or can be notified together with the handover notification from the CU to the UE. Thus, for example, when the CU only uses the mobile source beam / TRP, the UE does not need to send the Ack / Nack repetition after the beam / TRP handover, and therefore the signaling amount can be reduced.

[0419] The CU can retransmit downlink user data utilized via the mobile target beam / TRP and repeated with the Ack / Nack sent from the UE to the mobile source beam / TRP to the UE. This retransmission can be performed when the beam / TRP is switched between the Ack / Nack repetition from the UE to the CU and the retransmission of the downlink user data from the CU to the UE. Thus, the downlink user data retransmission process at the time of beam / TRP switching can be smoothly performed at the CU and the UE.

[0420] By using this Modification Example 1, the same effect as that of Embodiment 3 can be obtained for the notification of RRC parameters related to Ack / Nack repetition to the UE.

[0421] Modification Example 2 of Embodiment 3.

[0422] In Embodiment 3, the description centered on the notification of RRC parameters related to SR, but it can also be applied to RRC parameters related to SRS.

[0423] The above RRC parameters related to SRS can be the same as those in Modification Example 2 of Embodiment 2.

[0424] In this Modification Example 2, the method and content of the handover notification notified by the CU to the UE via the mobile pre-beam / TRP can be set to be the same as those in Embodiment 3. In addition, the method of notifying the RRC parameters related to SRS from the CU to the UE via the mobile target beam / TRP can apply the same method as the RRC parameter notification described in Embodiment 3. Thus, the UE can smoothly obtain the above RRC parameters after switching the communication target beam / TRP.

[0425] Similar to Embodiment 3, the CU can notify the UE of the parameters required for beam scanning. Thus, the UE can easily receive the beam scanning signal during the movement between beams / TRPs.

[0426] The above notification of the parameters required for beam scanning from the CU to the UE can use L1 / L2 signaling or MAC signaling. Thus, the same effect as that of Embodiment 3 can be obtained.

[0427] Similar to Embodiment 3, regarding the RRC parameters related to SRS, the CU can refrain from notifying the parameters with the same values also used in the mobile target beam / TRP. Therefore, the signaling amount generated by parameter notification can be reduced.

[0428] Similar to Embodiment 3, the CU and the UE can restore the value of the RRC parameter related to the SRS to the initial value when the beam / TRP of the UE is switched, or can maintain it. Whether to restore the value of the parameter at the time of beam / TRP switching of the UE to the initial value or to maintain it can be determined by the standard, or can be notified from the CU to the UE in advance. Alternatively, information on whether to restore the initial value or to maintain it can be notified from the CU to the UE together with the handover indication. Thereby, the same effect as in Embodiment 3 can be obtained.

[0429] The CU can notify the above-mentioned RRC parameter related to the SRS to the UE by using L1 / L2 signaling. Thereby, the parameter can be quickly notified to the UE.

[0430] Alternatively, the CU can notify the above-mentioned RRC parameter related to the SRS by using MAC signaling. Thereby, multi-level modulation can be performed, and the parameter can be notified with a smaller number of symbols. In addition, HARQ retransmission control is performed, so the reliability of parameter notification is improved.

[0431] Regarding the handover notification, similar to Embodiment 3, it can be notified from the CU to the UE by using L1 / L2 signaling, or can be notified from the CU to the UE by using MAC signaling. Thereby, the same effect as in Embodiment 3 can be obtained.

[0432] As an example of the process of RRC parameter notification related to the SRS and handover indication, replace the parameter related to the SR in step ST2003 of Figure 10 with the parameter related to the SRS.

[0433] Similar to Embodiment 3, the CU can send notifications of the parameter related to the SRS to the UE multiple times to increase the transmission power. Thereby, the reliability of the parameter notification related to the SRS can be improved. The same applies to the handover indication from the CU to the UE.

[0434] The UE can perform SRS transmission to the mobile target beam / TRP after receiving the parameter related to the SRS sent from the CU via the mobile target beam / TRP. Thereby, it is possible to suppress the transmission of an SRS that cannot be received by the mobile target beam / TRP before the UE receives the parameter related to the SRS.

[0435] The UE can make the SRS transmission request from the CU received from the mobile source beam / TRP valid. The above action of making the SRS transmission request from the CU valid can be performed when a beam / TRP handover occurs between the SRS transmission request and the SRS transmission. Thereby, smooth downlink user data processing can be performed in the CU and the UE when a beam / TRP handover occurs.

[0436] Alternatively, in the above, the UE may invalidate the SRS transmission request. In the above, the CU may retransmit the SRS transmission request to the UE via the mobile target beam / TRP. Thereby, the CU can perform scheduling adapted to the transmission status after beam / TRP switching.

[0437] In the SRS transmission from the UE to the CU, the CU may invalidate the SRS received by the mobile source beam / TRP. The invalidation action may be performed when beam / TRP switching occurs after the SRS transmission from the UE to the CU. The CU may notify the UE of the SRS transmission request via the mobile target beam / TRP. This notification may be used in an aperiodic SRS. Thereby, the CU can communicate with the UE using the uplink communication rate that correctly reflects beam / TRP switching.

[0438] By using this Modification Example 2, the same effects as those of Embodiment 3 can be obtained regarding the notification of RRC parameters related to SRS to the UE.

[0439] Modification Example 3 of Embodiment 3.

[0440] In Embodiment 3, the description is centered on the notification of RRC parameters related to SR, but it can also be applied to RRC parameters related to CQI / CSI.

[0441] The above RRC parameters related to CQI / CSI may be the same as those in Modification Example 3 of Embodiment 2.

[0442] In this Modification Example 3, the method and content of the handover notification notified by the CU to the UE via the pre-movement beam / TRP may be set to be the same as those in Embodiment 3. In addition, the method of notifying the RRC parameters related to CQI / CSI from the CU to the UE via the mobile target beam / TRP may be applied to the same method as the RRC parameter notification described in Embodiment 3. Thereby, the UE can smoothly obtain the above RRC parameters after switching the communication target beam / TRP.

[0443] Similar to Embodiment 3, the CU may notify the UE of the parameters required for beam scanning. Thereby, the UE can easily receive the beam scanning signal during the movement between beams / TRPs.

[0444] The above notification of the parameters required for beam scanning from the CU to the UE may use L1 / L2 signaling or MAC signaling. Thereby, the same effects as those of Embodiment 3 can be obtained.

[0445] Similar to Embodiment 3, regarding the RRC parameters related to CQI / CSI, the CU may not notify the parameters using the same values in the mobile target beam / TRP. Therefore, the signaling amount generated by parameter notification can be reduced.

[0446] Similar to Embodiment 3, when the beam / TRP of the UE is switched, the CU and the UE can restore the value of the RRC parameter related to CQI / CSI to its initial value or can maintain it. Whether to restore the value of the parameter at the time of beam / TRP switching of the UE to its initial value or to maintain it can be determined by a standard or can be notified from the CU to the UE in advance. Alternatively, information indicating whether to restore to the initial value or to maintain it can be notified from the CU to the UE together with the handover indication. Thereby, the same effect as in Embodiment 3 can be obtained.

[0447] The CU can notify the above-mentioned RRC parameter related to CQI / CSI to the UE by using L1 / L2 signaling. Thereby, the parameter can be quickly notified to the UE.

[0448] Alternatively, the CU can notify the above-mentioned RRC parameter related to CQI / CSI by using MAC signaling. Thereby, multi-level modulation can be performed, and the parameter can be notified with a smaller number of symbols. In addition, HARQ retransmission control is performed, so the reliability of parameter notification is improved.

[0449] Regarding the handover notification, similar to Embodiment 3, it can be notified from the CU to the UE by using L1 / L2 signaling or can be notified from the CU to the UE by using MAC signaling. Thereby, the same effect as in Embodiment 3 can be obtained.

[0450] As an example of the procedure of the RRC parameter notification related to CQI / CSI and the handover indication, Figure 10 the parameter related to SR in step ST2003 is replaced with the parameter related to CQI / CSI.

[0451] Similar to Embodiment 3, the CU can send notifications of the parameter related to CQI / CSI to the UE multiple times to increase the transmission power. Thereby, the reliability of the parameter notification related to CQI / CSI can be improved. The same applies to the handover indication from the CU to the UE.

[0452] The UE can perform CQI / CSI transmission to the mobile target beam / TRP after receiving the parameter related to CQI / CSI sent from the CU via the mobile target beam / TRP. Thereby, it is possible to suppress the transmission of CQI / CSI that cannot be received by the mobile target beam / TRP in the UE before receiving the parameter related to CQI / CSI.

[0453] The UE can make the CQI / CSI transmission request from the CU received by the mobile source beam / TRP valid. The action of making the CQI / CSI transmission request from the CU valid as described above can be performed when a beam / TRP handover occurs between the CQI / CSI transmission request and the CQI / CSI transmission. Thereby, the downlink user data processing can be smoothly performed in the CU and the UE when the beam / TRP handover occurs.

[0454] Alternatively, in the above, the UE can make the CQI / CSI transmission request invalid. In the above, the CU can retransmit the CQI / CSI transmission request to the UE via the mobile target beam / TRP. Thereby, the CU can perform scheduling adapted to the transmission status after the beam / TRP handover.

[0455] In the CQI / CSI transmission from the UE to the CU, the CU can invalidate the CQI / CSI received by the mobile source beam / TRP. The invalidation action can be performed when a beam / TRP handover occurs after the CQI / CSI transmission from the UE to the CU. The CU can notify the CQI / CSI transmission request to the UE via the mobile target beam / TRP. This notification can be used in aperiodic CQI / CSI. Thereby, the CU can communicate with the UE using the downlink communication rate that correctly reflects the beam / TRP handover.

[0456] By using this Modification Example 3, the same effect as in Embodiment 3 can be obtained for the notification of RRC parameters related to CQI / CSI to the UE.

[0457] Embodiment 4.

[0458] Different from Embodiment 2, for example, when the CU has PDCP, the DU has RLC, MAC, and PHY, or when the CU has PDCP and H-RLC, the DU has L-RLC, MAC, and PHY, in the beam movement within the cell or the TRP movement, the RRC parameters can be notified using RRC signaling.

[0459] However, beamforming is used in NR, so the beam / TRP movement within the cell occurs frequently. Therefore, there is a problem that the RRC signaling occurs frequently and the communication efficiency is reduced.

[0460] This Embodiment 4 discloses a method for solving the above problems.

[0461] Similarly to Embodiment 2, the CU notifies the UE in advance of the RRC parameters used for the beams or TRPs (hereinafter sometimes referred to as beams / TRPs) within the cell. The CU can perform this notification using RRC signaling. When switching the beams / TRPs, the CU notifies the UE of a beam / TRP switching instruction. This switching instruction may include an identifier indicating the target beam / TRP to be moved to. The CU can notify the UE of this switching instruction using L1 / L2 signaling or using MAC signaling. Thus, the CU can implement parameter changes accompanying beam / TRP switching with a smaller amount of signaling.

[0462] Similarly to Embodiment 2, the RRC parameters included in this notification may be parameters near the beam / TRP where the UE is located. The above-mentioned nearby beams / TRPs may include beams / TRPs adjacent to the beam / TRP where the UE is located. In addition, the RRC parameters included in this notification may also be composed only of parameters different from the parameters used for the beam / TRP where the UE is located. Thus, the size of this notification can be reduced.

[0463] Other methods are also disclosed. When switching the beams or TRPs, the CU notifies the UE of the RRC parameters used for the target beam / TRP to be moved to via the source beam / TRP to be moved from. When performing this notification, the notification between the CU and the source beam / TRP to be moved from can use the CU-DU interface. In addition, L1 / L2 signaling or MAC signaling can be used for the notification between the source beam / TRP to be moved from and the UE.

[0464] In the above, by notifying the UE using L1 / L2 signaling, parameters can be notified to the UE quickly. Thus, by using MAC signaling, multi-level modulation can be performed, so parameters can be notified with a smaller number of symbols. In addition, HARQ retransmission control is performed, so the reliability of parameter notification is improved.

[0465] The CU can notify the UE of the RRC parameters together with the switching instruction. Thus, the amount of signaling in beam / TRP switching can be reduced.

[0466] Alternatively, the CU can notify the UE of the switching instruction after notifying the RRC parameters. Thus, the CU can notify the UE of the switching instruction after confirming that the RRC parameters have been delivered. Therefore, it is possible to avoid, for example, non-delivery of SR from the UE due to non-delivery of RRC parameters related to SR and execution of random access due to exceeding the number of retransmissions.

[0467] Alternatively, the CU can notify the UE of the RRC parameters after notifying the switching instruction. In this case, the CU can notify the UE of the switching instruction together with the switching timing. Thus, even if it takes time for the UE to process switching the beam / TRP of the communication target, the switching can be performed smoothly.

[0468] The mobile source TRP can notify the CU of information indicating that the parameters have been confirmed to be delivered. The above information can be notified when MAC signaling is used for parameter notification. The CU can use the above information to notify the UE of the handover indication. Thereby, it is possible to prevent the handover indication notification when the parameters are not delivered, and thus it is possible to prevent the execution of random access due to, for example, the SR from the UE not being delivered and exceeding the retransmission count.

[0469] The RRC parameters can be the parameters shown in Section 6.3.2 of Non-Patent Document 12 in the same manner as in Embodiment 1. The RRC parameters can be, for example, parameters related to SR, parameters related to Ack / Nack repetition, parameters related to Sounding Reference Signal (SRS), or parameters related to CQI / CSI.

[0470] Similar to Embodiment 2, the CU can notify the UE of the parameters required for beam scanning. The parameters required for beam scanning can be set to the parameters shown in Embodiment 1. This notification can be performed via the mobile source beam / TRP. The parameters required for beam scanning can be set to the parameters in the mobile target beam / TRP. Thereby, the UE can easily receive the beam scanning signal during the movement between beams / TRPs.

[0471] Similar to Embodiment 2, the CU notifies the UE of the handover indication of the beam / TRP (hereinafter sometimes simply referred to as "handover indication") via the mobile source beam / TRP. The handover indication may or may not include an identifier indicating the mobile target beam / TRP. In addition, the handover indication may include information indicating the time of switching the beam / TRP.

[0472] The notification of the handover indication from the CU to the UE can use L1 / L2 signaling or MAC signaling. Among the above, by using L1 / L2 signaling to notify the UE, the handover indication can be quickly notified to the UE. In addition, by using MAC signaling, multi-level modulation can be performed, so the handover indication can be notified with a smaller number of symbols. In addition, HARQ retransmission control is performed, so the reliability of the handover indication notification is improved.

[0473] The mobile source TRP can notify the CU of information indicating that the handover indication has been confirmed to be delivered. The above information can be notified when MAC signaling is used for the notification of the handover indication. The CU can use the above information to switch the beam / TRP. Thereby, it is possible to prevent the beam / TRP from switching when the handover indication is not delivered, and thus it is possible to avoid the occurrence of RLF due to the UE losing the link with the gNB.

[0474] Among the above RRC parameters related to SR, they can be (1) to (3) disclosed in Embodiment 2. The CU may or may not notify the UE of the parameter indicating the maximum number of retransmissions of SR as an RRC parameter related to SR. Thus, the same effect as in Embodiment 2 can be obtained.

[0475] Similar to Embodiment 2, the CU can notify the UE of multiple parameters among the RRC parameters simultaneously. Thus, the signaling amount required for notification can be reduced.

[0476] Similar to Embodiment 2, the CU can notify the UE of the RRC parameters separately. Thus, the parameters can be notified even with fewer transmission resources.

[0477] The CU can notify the RRC parameters to the mobile target beam / TRP. Similar to Embodiment 1, in this notification, for example, the area of the control word of CPRI can be used, the ASN.1 format can be used, or other formats can be used. Thus, in addition to the same effect as in Embodiment 1, for example, after the beam / TRP is switched, the mobile target beam / TRP can quickly decode the uplink user data from the UE.

[0478] Similar to Embodiment 2, regarding the RRC parameters, the CU may not notify the parameters with the same value used in the mobile target beam / TRP. Therefore, the signaling amount generated by parameter notification can be reduced.

[0479] Similar to Embodiment 2, in the notification of the RRC parameters from the CU to the UE, an identifier indicating the parameter switch caused by the TRP / beam switch can be included. The UE can maintain the RRC parameters before the change. Thus, for example, the UE can prevent the SR from not reaching the mobile source TRP / beam due to the change of the above parameters during the SR transmission before the TRP / beam switch.

[0480] The CU and the UE can restore the value of the RRC parameters to the initial value or maintain it when the beam / TRP is switched. The initial value of the RRC parameters can be determined by the standard or notified from the CU to the UE using RRC signaling. Whether to restore the parameter value of the UE to the initial value or maintain it when the beam / TRP is switched can be determined by the standard or notified from the CU to the UE in advance. Or, the information indicating whether to restore the initial value or maintain it can be notified from the CU to the UE together with the handover indication. Thus, even when the parameter notification from the mobile source beam / TRP to the UE fails, the UE can use the RRC parameters before the change. Therefore, for example, when the same RRC parameters are used in the mobile target beam / TRP as in the mobile source beam / TRP, the UE can prevent the situation where the SR does not reach the mobile target beam / TRP.

[0481] Similar to Embodiment 2, the CU may or may not switch the beam / TRP when the handover indication from the mobile source beam / TRP to the UE exceeds the HARQ retransmission count. For various cases, the same effects as those in Embodiment 2 can be obtained.

[0482] Figure 11 It is a flowchart showing the beam / TRP handover when notifying parameters related to SR from the CU via the mobile source beam / TRP. Figure 11 An example of notifying parameters related to SR and a handover indication from the CU to the UE using MAC signaling is shown. Figure 11 In this case, the mobile source beam / TRP under the CU is denoted as S-beam / TRP, and the mobile target beam / TRP under the CU is denoted as T-beam / TRP. In addition, Figure 11 in this case, the black circle in the arrow represents the beam / TRP used for communication. The same step numbers are assigned to the same steps as those in Figure 9 and the common descriptions are omitted.

[0483] Figure 11 In step ST3001 of , the CU notifies the SR parameters to be notified to the UE to the S-beam / TRP. The notification of the parameters can use the CU-DU interface. In step ST3002, the S-beam / TRP notifies the above parameters to the UE. The notification of the parameters from the S-beam / TRP to the UE uses MAC signaling. L1 / L2 signaling can also be used. In step ST3003, the UE notifies the Ack for the SR parameter notification to the S-beam / TRP. The notification of the Ack can use the uplink control signal.

[0484] Figure 11 In step ST3004 of , the CU notifies the handover indication to be notified to the UE to the S-beam / TRP. The notification of the handover indication can use the CU-DU interface. In step ST3005, the S-beam / TRP notifies the handover indication to the UE. The notification of the handover indication from the S-beam / TRP to the UE uses MAC signaling. L1 / L2 signaling can also be used. In step ST3006, the UE notifies the Ack for the handover indication to the S-beam / TRP. In the case where the reception result from the UE is Nack, the CU may retransmit the handover indication via the S-beam / TRP.

[0485] Similar to Embodiment 2, the UE can send an uplink signal to the beam / TRP of the mobile source. The uplink signal can be a response to the L1 / L2 signaling for parameter notification from the CU. Additionally, it can be a response to the L1 / L2 signaling for handover indication from the CU. As the uplink signal, L1 / L2 signaling for response can be newly set. As the above response, new uplink control information (UCI) can be set. Thus, even when L1 / L2 signaling is used in the parameter notification or handover indication from the CU, the CU can perform delivery confirmation to the UE. Thereby, the reliability of the above L1 / L2 signaling can be improved.

[0486] For the new UCI, it can be set the same as in Embodiment 2. Thus, the same effect as in Embodiment 2 can be obtained.

[0487] In the above, the mobile source beam / TRP can notify the CU of information indicating that the L1 / L2 signaling for response has been received. Thus, the CU can grasp that the UE has correctly received the parameter notification or handover indication. Thereby, beam / TRP handover can be smoothly performed.

[0488] Regarding the RRC parameter notification using MAC signaling from the CU to the UE, the mobile source beam / TRP can notify the CU of information indicating that an Ack has been received for the RRC parameter notification. The CU can use the notified information to switch the beam / TRP in use. Thus, the CU can grasp that the UE has correctly received the RRC parameter notification, and therefore, beam / TRP handover can be smoothly performed.

[0489] Regarding the notification of the handover indication using MAC signaling from the CU to the UE, the mobile source beam / TRP can notify the CU of information indicating that an Ack has been received for the notification of the handover indication. The CU can use the notified information to switch the beam / TRP in use. Thus, the CU can grasp that the UE has correctly received the handover indication, and therefore, beam / TRP handover can be smoothly performed.

[0490] Similar to Embodiment 2, the UE can send an uplink signal to the beam / TRP of the mobile target. The uplink signal can be set as a confirmation signal for beam / TRP handover in the UE. The frequency resource of the SR can be used to send the confirmation signal. Or, the SR can be sent as the confirmation signal. Thus, even when L1 / L2 signaling is used in the handover indication from the CU, the CU can perform delivery confirmation to the UE. Thereby, the reliability of the above L1 / L2 signaling can be improved.

[0491] In the above, the UE can send the SR at the minimum period. Thus, the situation where the UE has switched the communication target beam / TRP can be confirmed with low latency.

[0492] In the above, the CU can ensure shared resources for SR that are shared by UEs existing within the coverage of the same beam / TRP. The UE can use the shared resources for SR to transmit SR. The shared resources for SR can be resources that allow UEs to compete with each other (contention-based). The location of the shared resources for SR can be determined in advance by the standard or notified by the CU to the subordinate UEs. This notification can be a broadcast or a UE-specific notification. The UE-specific notification in the above can be RRC dedicated signaling. Thus, even when the UE fails to receive RRC parameters, it can notify the CU of the situation where beam / TRP switching has been performed.

[0493] Similar to Embodiment 2, the UE can set the location of the SR shared resources as the initial value of the RRC parameters related to SR at the time of the above-mentioned communication target beam / TRP switching. Thus, even when the UE fails to receive RRC parameters, it can notify the CU of the situation where beam / TRP switching has been performed.

[0494] The UE in the above can also transmit SRS to the beam / TRP of the moving target. The SRS can be aperiodic or periodic. The UE can transmit the SRS a predetermined number of times to the beam / TRP of the moving target. This number of transmissions can be determined by the standard or notified in advance by the CU to the UE. This notification can be performed using RRC signaling. Thus, even when there is no uplink user data transmitted to the CU, the UE can notify the CU of the situation where communication target beam / TRP switching has been performed.

[0495] Similar to Embodiment 2, the CU can use the above SR to determine whether there is communication target beam / TRP switching in the UE. For example, in the case where there is no SR notification from the UE, the CU can determine that the UE has not switched the communication target beam / TRP. The CU can re-notify the parameters and the switching indication from the mobile source beam / TRP. This re-notification can be performed using the above determination result. Thus, for example, it is possible to prevent RLF or random access that occurs due to the UE failing to receive the parameters or switching indication related to SR. Thus, the time for beam / TRP switching can be shortened.

[0496] Similar to Embodiment 2, the CU can notify the UE of the parameters multiple times. In addition, the CU can increase the transmission power for notifying the UE of the parameters. Thus, the reliability of parameter notification can be improved. The number of times of parameter notification can be determined by the standard or notified in advance by the CU to the UE. This notification can be performed using RRC signaling.

[0497] Similar to Embodiment 2, for the handover indication notification to the UE, it can be sent multiple times in the same way as the parameter notification, and the power can also be increased. Thus, the reliability of the handover indication notification can be improved.

[0498] Similar to Embodiment 2, the UE can perform beam switching of the communication target by using the parameter notification received from the CU. The beam switching can be accompanied by beam scanning and random access. The beam switching can be performed by using the reception of one or more of the parameters. The beam switching can be performed after a predetermined time has elapsed after the UE receives one or more parameters. The above-mentioned predetermined time can be determined by a standard or can be notified to the UE by the CU in advance. This notification can be performed by using RRC signaling. Thus, even when the UE cannot correctly receive the handover indication from the CU to the UE, the UE can switch the beam of the communication target. In addition, the time required to retransmit the handover notification from the CU to the UE is not required.

[0499] For the SR transmission from the UE, the CU can invalidate the SR received by the mobile source beam / TRP. When a beam / TRP switch occurs between SR reception and uplink scheduling grant transmission, the CU can invalidate the SR. In the above, the UE can retransmit the SR to the mobile target beam / TRP. Thus, the situation where the retransmitted SR from the UE fails to reach the CU can be prevented.

[0500] Alternatively, regarding the beam / TRP switch after the above-mentioned SR transmission from the UE, the CU can make the SR received by the mobile source beam / TRP valid. The mobile source beam / TRP can forward the SR to the mobile target beam / TRP. This forwarding can be via the CU. In the above, the information indicating that the SR has been received can be used instead of the SR. Thus, even when a beam / TRP switch occurs between SR reception and uplink scheduling grant transmission, a series of processes including SR transmission, uplink scheduling grant reception, and uplink user data transmission can be smoothly performed in the UE.

[0501] Regarding the uplink scheduling grant notification from the CU to the UE, the CU and the UE can invalidate the uplink scheduling grant sent from the mobile source beam / TRP. When a beam / TRP handover occurs between the uplink scheduling grant and the uplink user data, the CU and the UE can invalidate the uplink scheduling grant. In the above, the mobile target beam / TRP can retransmit the uplink scheduling grant to the UE. In the retransmission of the above uplink scheduling grant, the mobile source beam / TRP can request the mobile target beam / TRP to retransmit the uplink scheduling grant to the UE. Alternatively, the UE can restart the SR transmission to the mobile target beam / TRP. In the above, whether the UE restarts the SR transmission is determined by the standard. Or it can be notified to the UE by the CU. The above notification can be pre - performed by RRC signaling, can be performed by MAC signaling, or can be performed by L1 / L2 signaling. In an example where the above notification is performed using MAC signaling or L1 / L2 signaling, the above notification can be performed together with the handover notification. Thus, the UE can receive the uplink scheduling grant corresponding to the uplink resource usage status of the mobile target beam / TRP for uplink user data transmission.

[0502] Alternatively, regarding the above beam / TRP handover from the mobile source beam / TRP to the beam / TRP after notifying the UE of the uplink scheduling grant, the CU and the UE can validate the uplink scheduling grant sent from the mobile source beam / TRP. The mobile source beam / TRP can notify the mobile target beam / TRP of the information regarding the uplink scheduling grant. The UE can use the uplink scheduling grant to transmit uplink user data to the mobile target beam / TRP. Thus, the signaling volume between the CU and the UE can be reduced.

[0503] It can be determined by the standard whether to validate the uplink scheduling grant as above, or it can be notified from the CU to the UE. The notification from the gNB to the UE can be pre - performed by RRC signaling, can be performed by MAC signaling, or can be performed by L1 / L2 signaling. As an example of the case where the uplink scheduling grant is validated, it can be set as the case where the mobile target beam / TRP can use the uplink resources indicated by the scheduling grant for this UE. The mobile source beam / TRP can notify the mobile target beam / TRP of the information regarding the uplink scheduling grant. Thus, the mobile target beam / TRP can judge whether to validate or invalidate the uplink scheduling grant, and thus flexible scheduling can be achieved.

[0504] In an example where the above notification is performed using MAC signaling or L1 / L2 signaling, the above notification can be performed together with the handover notification. Thus, the CU can perform scheduling corresponding to the uplink resource usage status in the mobile target beam / TRP with less signaling.

[0505] For uplink user data transmission from the UE to the CU, the mobile target beam / TRP can send an Ack / Nack of the mobile source beam / TRP for the uplink user data received from the UE to the UE. The above-mentioned Ack / Nack transmission from the mobile target beam / TRP to the UE can be performed when a beam / TRP handover occurs between the uplink user data transmission from the UE and the Ack / Nack notification for the uplink user data. In the above, the mobile source beam / TRP can notify the mobile target beam / TRP of the information indicating the Ack / Nack for the uplink user data. Thereby, the beam / TRP handover after the uplink user data transmission can be smoothly performed.

[0506] The mobile source beam / TRP can notify the mobile target beam / TRP of the information related to the decoding result of the uplink user data received from the UE. This information can be, for example, the soft decision value of the uplink user data. Thereby, the mobile target beam / TRP can synthesize and decode the first reception result and the retransmission reception result of the uplink user data. Thereby, the probability of reception error can be reduced.

[0507] According to the present Embodiment 4, in the case where the CU has PDCP, the DU has RLC, MAC, and PHY, or in the case where the CU has PDCP and H-RLC, the DU has L-RLC, MAC, and PHY, the same effects as those of Embodiment 2 can also be obtained. In the above cases, the signaling amount between the beams / TRPs can be reduced.

[0508] In Embodiment 4, a base station device in which the CU and the DU are separated is shown as an example, but it can also be applied to a base station device in which the CU and the DU are not separated. This base station device can be a base station device that does not share RRC parameters between the beams. In addition, this base station device can be, for example, a base station that performs different HARQ scheduling for each beam, a base station that has different RLC layers for each beam, or a base station that combines both of the above. When applying Embodiment 4 to this base station device, the gNB can be used to replace the CU. Thereby, in the beam handover within the cell, the RRC parameters can be notified from the gNB to the UE via the mobile source beam, and the number of UEs accommodated in the cells spatially separated by the beams can be increased. The parameters can be quickly notified from the gNB to the UE.

[0509] In Embodiment 4, a base station device that notifies RRC parameters to a UE by a mobile source beam / TRP is shown as an example, but RRC parameters may also be notified by other beams / TRPs. The above-mentioned other beams / TRPs may be, for example, beams / TRPs for transmitting control information. Thus, for example, in a base station device having beams / TRPs for user data transmission / reception and control information transmission / reception, RRC parameters can be notified with a smaller amount of signaling, and thus RRC parameter notification during beam movement can be performed quickly.

[0510] According to Embodiment 4, a communication system is provided in the same manner as in Embodiment 2. The communication system includes, for example, a communication terminal device and a base station device that performs wireless communication with the communication terminal device using a wireless beam. A cell formed by the base station device is spatially separated by a plurality of wireless beams under the base station device. When the communication terminal device moves from the coverage area of a first wireless beam to the coverage area of a second wireless beam, the base station device changes the RRC (Radio Resource Control) parameters used for the communication terminal device from first RRC parameters for the first wireless beam to second RRC parameters for the second wireless beam. In addition, the plurality of wireless beams may be formed by a plurality of DUs (in other words, TRPs) as Figure 8 illustrated, may be formed by one DU, or may be formed by a base station device integrating a CU and a DU.

[0511] According to this configuration, the RRC parameters used for the communication terminal device are changed according to the change in the wireless beam used for the communication terminal device. Therefore, the accommodation number of the communication terminal device can be increased as described above.

[0512] Here, the above structure can be deformed in various ways as described above. In particular, according to Embodiment 4, for example, the following communication system is provided: That is, the base station device includes at least one DU (Distributed Unit) that outputs multiple radio beams and a CU (Central Unit) that controls at least one DU. At least one DU has a MAC (Medium Access Control) function. The CU notifies the communication terminal device of the second RRC parameter through the first radio beam using L1 / L2 signaling or MAC signaling, and notifies the communication terminal device of the handover instruction from the first radio beam to the second radio beam through the first radio beam using L1 / L2 signaling or MAC signaling. In the above, the DU may have an RLC (Radio Link Control) function. Or, as another example, the following communication system is provided: That is, the base station device has a function of outputting multiple radio beams and a MAC function. The base station device notifies the communication terminal device of the second RRC parameter, and notifies the communication terminal device of the handover instruction from the first radio beam to the second radio beam using the first radio beam.

[0513] In addition, various deformations are provided as described in the following Modification Examples 1 to 4.

[0514] Modification Example 1 of Embodiment 4.

[0515] In Embodiment 4, the description is centered on the notification of RRC parameters related to SR, but it can also be applied to RRC parameters related to Ack / Nack repetition.

[0516] The above RRC parameters related to Ack / Nack repetition can be the same as those in Modification Example 1 of Embodiment 2.

[0517] In this Modification Example 1, the method and content of the handover notification notified by the CU to the UE via the pre-movement beam / TRP can be set to be the same as those in Embodiment 4. In addition, the method of notifying the RRC parameter related to Ack / Nack repetition from the CU to the UE via the pre-movement beam / TRP can be applied to the same method as the RRC parameter notification described in Embodiment 4. Thus, the same effect as that of Embodiment 4 can be obtained.

[0518] Similar to Embodiment 4, the CU can notify the UE of the parameters required for beam scanning. The method of notifying the parameters can be the same as that in Embodiment 4. Thus, the UE can easily receive the beam scanning signal during the movement between beams / TRPs.

[0519] In the above, the notification of the parameters required for beam scanning from the CU to the UE can use L1 / L2 signaling or MAC signaling. Thus, the same effect as that of Embodiment 4 can be obtained.

[0520] Similar to Embodiment 4, in the notification in which the CU notifies the UE of the RRC parameters related to Ack / Nack repetition, an identifier indicating parameter switching caused by TRP / beam switching may be included. The UE may maintain the RRC parameters related to Ack / Nack repetition before the change. Thereby, the UE can prevent a reduction in the reliability of sending Ack / Nack to the mobile source TRP / beam due to parameter changes in the Ack / Nack transmission before the TRP / beam switching.

[0521] Similar to Embodiment 4, regarding the RRC parameters related to Ack / Nack repetition, the CU may not notify the parameters with the same values also used in the mobile target beam / TRP. Therefore, the signaling amount generated by parameter notification can be reduced.

[0522] Similar to Embodiment 4, the CU and the UE may restore the value of the RRC parameters related to Ack / Nack repetition to the initial value or maintain it when the beam / TRP of the UE is switched. The initial value of the RRC parameters may be determined by a standard or may be notified in advance from the CU to the UE by using RRC signaling. Whether to restore the value of the parameters at the time of beam / TRP switching of the UE to the initial value or maintain it may be determined by a standard or may be notified in advance from the CU to the UE. Alternatively, information indicating whether to restore to the initial value or maintain it may be notified from the CU to the UE together with the handover indication. Thereby, the same effect as in Embodiment 4 can be obtained.

[0523] Similar to Embodiment 4, the CU may notify the UE of the RRC parameters related to Ack / Nack repetition together with the handover indication. Thereby, the signaling amount in the beam / TRP switching can be reduced.

[0524] Alternatively, the CU may notify the UE of the handover indication after notifying the RRC parameters related to Ack / Nack repetition. Thereby, it is possible to prevent the UE from applying the parameters before the change after the beam / TRP switching, and it is possible to avoid a situation where the repeated Ack / Nack from the UE is not delivered and the reliability of the Ack / Nack notification is reduced due to the non-delivery of the repeated Ack / Nack from the UE.

[0525] Alternatively, the CU may notify the UE of the RRC parameters related to Ack / Nack repetition after notifying the handover indication. In this case, the CU may notify the handover indication together with the handover timing to the UE. Thereby, even if the process of switching the communication target beam / TRP in the UE takes time, the switching can be performed smoothly.

[0526] The CU can use L1 / L2 signaling to notify the UE of the above-mentioned RRC parameters related to Ack / Nack repetition. Thus, the parameters can be quickly notified to the UE.

[0527] Alternatively, the CU can use MAC signaling to notify the above-mentioned RRC parameters related to Ack / Nack repetition. Thus, multi-level modulation can be performed, and the parameters can be notified with fewer symbols. In addition, HARQ retransmission control is performed, so the reliability of parameter notification is improved.

[0528] Similar to Embodiment 4, the mobile source TRP can notify the CU of information indicating that the parameter confirmation has been delivered. The above information can be notified when MAC signaling is used for parameter notification. The CU can use the above information to notify the UE of the handover indication. Thus, it is possible to avoid the non-delivery of repeated Ack / Nack from the UE due to the non-delivery of the parameters, and improve the reliability of Ack / Nack transmission.

[0529] Regarding the handover notification, similar to Embodiment 4, it can be notified from the CU to the UE using L1 / L2 signaling, or it can be notified from the CU to the UE using MAC signaling. Thus, the same effect as Embodiment 4 can be obtained.

[0530] As an example of the process of RRC parameter notification and handover indication related to Ack / Nack repetition, replace the parameters related to SR in Figure 11 steps ST3001 and ST3002 with the parameters related to Ack / Nack repetition.

[0531] Similar to Embodiment 4, the CU can send multiple notifications of the parameters related to Ack / Nack repetition to the UE, increasing the transmission power. Thus, the reliability of parameter notification can be improved. The same applies to the handover indication from the CU to the UE.

[0532] Whether it is the mobile source beam / TRP or the mobile target beam / TRP, the UE can refrain from notifying Ack / Nack for the downlink user data received from the CU via the mobile source beam / TRP. The above actions of the UE can be performed when there is a beam / TRP handover between the downlink user data and Ack / Nack. The mobile source beam / TRP can transfer the above-mentioned downlink user data to the mobile target beam / TRP. The mobile target beam / TRP can transfer the above-mentioned downlink user data to the UE. Thus, it is possible to prevent the loss of downlink user data due to beam / TRP handover.

[0533] As another example, the UE can notify the mobile target beam / TRP of the Ack / Nack for the downlink user data from the CU received from the mobile source beam / TRP. The above-mentioned Ack / Nack notification can be performed when a beam / TRP handover occurs between the downlink user data and the Ack / Nack. The mobile target beam / TRP can notify the mobile source beam / TRP of the above-mentioned Ack / Nack reception result. Thereby, the signaling amount related to the downlink user data when a beam / TRP handover occurs can be reduced.

[0534] In the above, the mobile source beam / TRP can transfer the above-mentioned downlink user data to the mobile target beam / TRP. The above-mentioned transfer can be performed when a Nack notification is received from the UE for the downlink user data. The mobile target beam / TRP can retransmit to the UE using the transferred downlink user data. Thereby, the retransmission process of the downlink user data during a beam / TRP handover can be smoothly performed.

[0535] Regarding the judgment of the Ack / Nack received from the UE, the mobile source beam / TRP can use only the reception result in this beam / TRP, or can also use the reception result in the mobile target beam / TRP together. The mobile target beam / TRP can transfer the Ack / Nack reception result from the UE to the mobile source beam / TRP. The above action can be performed when the beam / TRP is switched during the Ack / Nack repetition from the UE to the mobile source beam / TRP. By using only the reception result in the mobile source beam / TRP, the reception action of the Ack / Nack repetition from the UE can be performed quickly. By using the reception result in the mobile target beam / TRP together, the reliability of the Ack / Nack repetition in the mobile source beam / TRP can be improved. Regarding whether the mobile source beam / TRP uses only the reception result in this beam / TRP or uses the reception result in the mobile target beam / TRP together, it can be determined by a standard or can be appropriately switched by the CU. By appropriately switching by the CU, for example, an appropriate reception action can be selected according to the transmission status in the mobile source beam / TRP, so the flexibility of the reception process of the Ack / Nack repetition in the gNB can be improved.

[0536] In the above, the mobile target beam / TRP can replace the mobile source beam / TRP to perform repeated Ack / Nack reception processing. The mobile target beam / TRP can use only the reception result in the current beam / TRP, or can also use the reception result in the mobile source beam / TRP. The mobile source beam / TRP can forward the Ack / Nack reception result from the UE to the mobile target beam / TRP. In this way, the same effect as above can be obtained. Whether the mobile target beam / TRP uses only the reception result in the current beam / TRP, or uses the reception result in the mobile source beam / TRP, can be determined by the standard, or can be switched appropriately by the CU.

[0537] In the above, which of the mobile source beam / TRP and the mobile target beam / TRP performs the Ack / Nack reception operation can be determined by the standard or predetermined by the CU. This can prevent erroneous operations caused by inconsistent Ack / Nack reception results between the mobile source beam / TRP and the mobile target beam / TRP.

[0538] The mobile target beam / TRP can retransmit downlink user data to the UE using the Ack / Nack repetition sent from the UE to the mobile source beam / TRP. This retransmission can be performed when the beam / TRP is switched between the Ack / Nack repetition from the UE to the mobile source beam / TRP and the retransmission of downlink user data to the UE. The mobile source beam / TRP can forward the retransmitted data to the mobile target beam / TRP. Thus, the downlink user data retransmission processing when the beam / TRP switching occurs can be smoothly performed.

[0539] By using this variation 1, the same effect as that of implementation example 4 can be obtained regarding the notification of RRC parameters related to Ack / Nack repetition to the UE.

[0540] Modification 2 of Implementation 4.

[0541] In Embodiment 4, notification of RRC parameters related to SR is mainly described, but it can also be applied to RRC parameters related to SRS.

[0542] The RRC parameters related to SRS described above may be the same as those in variation 2 of implementation example 2.

[0543] In this variation 2, the method and content of the switching notification that the CU notifies the UE via the beam / TRP before moving can be set to be the same as those in implementation mode 4. In addition, the method for the CU to notify the UE of the RRC parameter notification related to SRS via the beam / TRP before moving can apply the same method as the RRC parameter notification described in implementation mode 4. As a result, the same effect as that of implementation mode 4 can be obtained.

[0544] Similar to Embodiment 4, the CU can notify the UE of the parameters required for beam scanning. The method of notifying the parameters can be the same as that in Embodiment 4. Thus, the UE can easily receive the beam scanning signal during the movement between beams / TRPs.

[0545] For the notification of the parameters required for beam scanning from the CU to the UE described above, L1 / L2 signaling or MAC signaling can be used. Thus, the same effect as that in Embodiment 4 can be obtained.

[0546] Similar to Embodiment 4, in the notification of the RRC parameters related to the SRS by the CU to the UE, an identifier indicating the parameter switching caused by the TRP / beam switching can be included. The UE can keep the RRC parameters related to the SRS before the change. Thus, in the SRS transmission before the TRP / beam switching, the UE can prevent the random access action and the decrease in the uplink communication rate caused by the failure of the SRS to reach the destination.

[0547] Similar to Embodiment 4, regarding the RRC parameters related to the SRS, the CU may not notify the parameters that use the same values even in the moving target beam / TRP. Therefore, the signaling amount generated by the parameter notification can be reduced.

[0548] Similar to Embodiment 4, the CU and the UE can restore the value of the RRC parameters related to the SRS to the initial value or keep it when the beam / TRP of the UE is switched. The initial value of the RRC parameters can be determined by the standard or notified from the CU to the UE using RRC signaling. Whether to restore the value of the parameters to the initial value or keep it when the beam / TRP of the UE is switched can be determined by the standard or notified from the CU to the UE in advance. Alternatively, the information on whether to restore the initial value or keep it can be notified from the CU to the UE together with the handover indication. Thus, the same effect as that in Embodiment 4 can be obtained.

[0549] Similar to Embodiment 4, the CU can notify the UE of the RRC parameters related to the SRS together with the handover indication. Thus, the signaling amount during the beam / TRP switching can be reduced.

[0550] Alternatively, the CU can notify the handover indication to the UE after the notification of the RRC parameters related to the SRS. Thus, it is possible to avoid applying the RRC parameters related to the SRS before the change in the UE after the beam / TRP switching, and it is possible to avoid the failure of the SRS from the UE to reach the destination and the random access action caused by the failure of the SRS from the UE to reach the destination, and to reduce the uplink communication rate.

[0551] Alternatively, after notifying the handover indication, the CU may notify the UE of the RRC parameters related to the SRS. In this case, the CU may notify the UE of the handover indication together with the handover timing. Thus, even if it takes time for the UE to process the beam / TRP for switching the communication target, the handover can be smoothly performed.

[0552] The CU may notify the UE of the above-mentioned RRC parameters related to the SRS by using L1 / L2 signaling. Thus, the parameters can be quickly notified to the UE.

[0553] Alternatively, the CU may notify the above-mentioned RRC parameters related to the SRS by using MAC signaling. Thus, multi-level modulation can be performed, and the parameters can be notified with a smaller number of symbols. In addition, HARQ retransmission control is performed, so the reliability of the parameter notification is improved.

[0554] Similar to Embodiment 4, the mobile source TRP may notify the CU of the information indicating that the parameter confirmation has been delivered. The above information may be notified when MAC signaling is used for parameter notification. The CU may notify the UE of the handover indication by using the above information. Thus, it is possible to avoid the non-delivery of the SRS from the UE due to the non-delivery of the parameters, and prevent the occurrence of the random access operation and the decrease in the uplink communication rate.

[0555] Regarding the handover notification, similar to Embodiment 4, it may be notified from the CU to the UE by using L1 / L2 signaling, or may be notified from the CU to the UE by using MAC signaling. Thus, the same effect as Embodiment 4 can be obtained.

[0556] As an example of the procedure for notifying the RRC parameters related to the SRS and the handover indication, Figure 11 the SR-related parameters in steps ST3001 and ST3002 may be replaced with the SRS-related parameters.

[0557] Similar to Embodiment 4, the CU may send multiple notifications of the SRS-related parameters to the UE to increase the transmission power. Thus, the reliability of the parameter notification can be improved. The same applies to the handover indication from the CU to the UE.

[0558] The UE can perform SRS transmission for the SRS transmission indication received from the mobile source beam / TRP to the mobile target beam / TRP. The above SRS transmission from the UE to the mobile target beam / TRP can be performed when a beam / TRP switch occurs between the SRS transmission indication and the SRS transmission. The above SRS transmission can be an aperiodic SRS transmission. The mobile source beam / TRP can notify the mobile target beam / TRP of the situation where the UE has been indicated for SRS transmission. Thereby, the SRS transmission process when a beam / TRP switch occurs can be smoothly performed in the CU and the UE.

[0559] In the above, the UE can invalidate the SRS transmission indication received from the mobile source beam / TRP. Thereby, the signaling from the mobile source beam / TRP to the mobile target beam / TRP can be reduced.

[0560] The mobile source beam / TRP can invalidate the SRS transmitted from the UE to this beam. The action of invalidating the SRS can be performed when the beam / TRP is switched after the SRS transmission. Thereby, the mobile target beam / TRP can perform scheduling adapted to the transmission status after the beam / TRP switch.

[0561] By using this Modification Example 2, the same effect as in Embodiment 4 can be obtained for the notification of RRC parameters related to SRS to the UE.

[0562] Modification Example 3 of Embodiment 4.

[0563] In Embodiment 4, the description is centered on the notification of RRC parameters related to SR, but it can also be applied to RRC parameters related to CQI / CSI.

[0564] The above RRC parameters related to CQI / CSI can be the same as those in Modification Example 3 of Embodiment 2.

[0565] In this Modification Example 3, the method and content of the handover notification notified by the CU to the UE via the pre-movement beam / TRP can be set to be the same as those in Embodiment 4. In addition, the method of notifying the RRC parameters related to CQI / CSI from the CU to the UE via the pre-movement beam / TRP can be applied to the same method as the RRC parameter notification described in Embodiment 4. Thereby, the same effect as in Embodiment 4 can be obtained.

[0566] Similar to Embodiment 4, the CU can notify the UE of the parameters required for beam scanning. The method of notifying the parameters can be the same as that in Embodiment 4. Thereby, the UE can easily receive the beam scanning signal during the movement between beams / TRPs.

[0567] The notification of the parameters required for beam scanning from the CU to the UE described above can use L1 / L2 signaling or MAC signaling. Thus, the same effect as in Embodiment 4 can be obtained.

[0568] Similar to Embodiment 4, in the notification of RRC parameters related to CQI / CSI from the CU to the UE, an identifier indicating parameter switching caused by TRP / beam switching can be included. The UE can maintain the RRC parameters related to CQI / CSI before the change. Thus, the UE can prevent a decrease in downlink communication rate due to non-delivery of CQI / CSI during CQI / CSI transmission before TRP / beam switching.

[0569] Similar to Embodiment 4, regarding the RRC parameters related to CQI / CSI, the CU may also not notify parameters that use the same value even in a moving target beam / TRP. Therefore, the signaling amount generated by parameter notification can be reduced.

[0570] The CU and the UE can return the value of the RRC parameters related to CQI / CSI to the initial value or maintain it when the beam / TRP of the UE is switched. The initial value of the RRC parameters can be determined by a standard or notified from the CU to the UE using RRC signaling. Whether to restore the parameter value to the initial value or maintain it when the beam / TRP of the UE is switched can be determined by a standard or notified from the CU to the UE in advance. Alternatively, information indicating whether to restore to the initial value or maintain it can be notified from the CU to the UE together with the handover indication. Thus, the same effect as in Embodiment 4 can be obtained.

[0571] Similar to Embodiment 4, the CU can notify the RRC parameters related to CQI / CSI to the UE together with the handover indication. Thus, the signaling amount during beam / TRP switching can be reduced.

[0572] Alternatively, the CU can notify the handover indication to the UE after notifying the RRC parameters related to CQI / CSI. Thus, it is possible to avoid applying the RRC parameters related to CQI / CSI before the change in the UE after beam / TRP switching, and to avoid non-delivery of CQI / CSI from the UE and a decrease in downlink communication rate due to non-delivery of CQI / CSI from the UE.

[0573] Alternatively, the CU can notify the RRC parameters related to CQI / CSI to the UE after notifying the handover indication. In this case, the CU can notify the handover indication and the handover timing to the UE together. Thus, even if the process of switching the communication target beam / TRP in the UE takes time, the switching can be performed smoothly.

[0574] The CU can use L1 / L2 signaling to notify the UE of the above RRC parameters related to CQI / CSI. Thus, the parameters can be quickly notified to the UE.

[0575] Alternatively, the CU can use MAC signaling to notify the above RRC parameters related to CQI / CSI. Thus, multi-level modulation can be performed, and the parameters can be notified with fewer symbols. In addition, HARQ retransmission control is performed, so the reliability of parameter notification is improved.

[0576] Similar to Embodiment 4, the mobile source TRP can notify the CU of information indicating that the parameter confirmation has been delivered. The above information can be notified when MAC signaling is used for parameter notification. The CU can use the above information to notify the UE of the handover indication. Thus, it is possible to avoid the non-delivery of CQI / CSI from the UE due to the non-delivery of the parameters, and prevent the reduction of the downlink communication rate.

[0577] Regarding the handover notification, similar to Embodiment 4, it can be notified from the CU to the UE using L1 / L2 signaling, or it can be notified from the CU to the UE using MAC signaling. Thus, the same effect as Embodiment 4 can be obtained.

[0578] As an example of the process of RRC parameter notification and handover indication related to CQI / CSI, replace the parameters related to SR in Figure 11 steps ST3001 and ST3002 with the parameters related to CQI / CSI.

[0579] Similar to Embodiment 4, the CU can send multiple notifications of parameters related to CQI / CSI to the UE, increasing the transmission power. Thus, the reliability of parameter notification can be improved. The same applies to the handover indication from the CU to the UE.

[0580] The UE can perform CQI / CSI transmission for indicating CQI / CSI transmission received from the mobile source beam / TRP to the mobile target beam / TRP. The above CQI / CSI transmission from the UE to the mobile target beam / TRP can be performed when a beam / TRP handover occurs between the CQI / CSI transmission indication and the CQI / CSI transmission. The above CQI / CSI transmission can be an aperiodic CQI / CSI transmission. The mobile source beam / TRP can notify the mobile target beam / TRP of information indicating that the CQI / CSI transmission indication has been given to the UE. Thus, the CQI / CSI transmission process when a beam / TRP handover occurs can be smoothly performed among the mobile source beam / TRP, the mobile target beam / TRP, and the UE.

[0581] The mobile source beam / TRP can invalidate the CQI / CSI sent from the UE to this beam. The action of invalidating the CQI / CSI can be performed when the beam / TRP is switched after the CQI / CSI is sent. The mobile source beam / TRP can notify the mobile target beam / TRP of the information indicating that the CQI / CSI transmission indication has been given to the UE. The mobile target beam / TRP can retransmit the CQI / CSI transmission indication to the UE. The UE can retransmit the CQI / CSI to the mobile target beam / TRP. Thus, the mobile target beam / TRP can perform scheduling adapted to the transmission status after the beam / TRP is switched.

[0582] By using this Modification Example 3, the same effect as in Embodiment 4 can be obtained for the notification of the RRC parameters related to the CQI / CSI to the UE.

[0583] Modification Example 4 of Embodiment 4.

[0584] In Embodiment 4, the description centered on the notification of the RRC parameters related to the SR, but it can also be applied to the RRC parameters related to the RLC.

[0585] As the RRC parameters related to the RLC in the above, the following (1) to (8) are shown.

[0586] (1) A timer for determining whether retransmission of the RLC PDU is required. For example, T-PollRetransmit described in Non-Patent Document 12.

[0587] (2) The number of RLC PDUs used as the interval for the transmitting entity of the RLC to send polling to the receiving entity. For example, PollPDU described in Non-Patent Document 12.

[0588] (3) The amount of RLC PDU data used as the interval for the transmitting entity of the RLC to send polling to the receiving entity. For example, PollByte described in Non-Patent Document 12.

[0589] (4) The maximum number of retransmissions in the ARQ of the RLC. For example, maxRetxThreshold described in Non-Patent Document 12.

[0590] (5) A timer for reordering the RLC PDU. For example, T-reordering described in Non-Patent Document 12.

[0591] (6) The minimum transmission interval of the RLC status PDU. For example, T-StatusProhibit described in Non-Patent Document 12.

[0592] (7) Size of the sequence number of the RLCPDU. For example, the SN-FieldLength described in Non-Patent Document 12.

[0593] (8) Combinations of the above (1) to (7).

[0594] According to the above (1), for example, in a beam / TRP with an unstable transmission environment, by reducing the value of the timer used to determine whether to retransmit the RLCPDU, the delay in the communication between the UE and the CU can be reduced.

[0595] According to the above (2), for example, in a beam / TRP with an unstable transmission environment, by reducing the number of RLCPDUs between polls, the delay in the communication between the UE and the CU can be reduced.

[0596] According to the above (3), for example, in a beam / TRP with an unstable transmission environment, by reducing the size of the RLCPDU between polls, the delay in the communication between the UE and the CU can be reduced.

[0597] According to the above (4), for example, in a beam / TRP with an unstable transmission environment, by increasing the maximum number of retransmissions of the RLCPDU, the reliability of the RLCPDU transmission and reception can be improved.

[0598] According to the above (5), for example, in a beam / TRP with an unstable transmission environment, by increasing the value of the timer for reordering, the loss of the RLCPDU can be prevented.

[0599] According to the above (6), for example, in a beam / TRP with an unstable transmission environment, by shortening the transmission interval of the status PDU, a communication with low delay and high reliability can be ensured.

[0600] According to the above (7), for example, in a beam / TRP with an unstable transmission environment, by increasing the size of the sequence number, the loss of the RLCPDU can be prevented.

[0601] In this Modification 1, the method and content of the handover notification notified by the CU to the UE via the pre-movement beam / TRP can be set to be the same as those in Embodiment 4. In addition, the method of notifying the RRC parameters related to the RLC by the CU to the UE via the pre-movement beam / TRP can be applied using the same method as the RRC parameter notification described in Embodiment 4. Thus, the same effects as those in Embodiment 4 can be obtained.

[0602] Similar to Embodiment 4, the CU can notify the UE of the parameters required for beam scanning. The method of notifying the parameters can be the same as that in Embodiment 4. Thus, the same effects as those in Embodiment 4 can be obtained.

[0603] The notification of the parameters required for beam scanning from the CU to the UE can use L1 / L2 signaling or MAC signaling. Thus, the same effect as in Embodiment 4 can be obtained.

[0604] Similar to Embodiment 4, in the notification from the CU to the UE of the RRC parameters related to the RLC, an identifier indicating the parameter switch caused by the TRP / beam switching can be included. The UE can maintain the RRC parameters related to the RLC before the change, or can use the changed parameters after the TRP / beam switching. Thus, before the TRP / beam switching, the RLC re-establishment of the UE and the mobile source beam / TRP accompanied by the change of the RRC parameters related to the RLC can be prevented, and the communication loss caused thereby can be prevented.

[0605] Similar to Embodiment 4, regarding the RRC parameters related to the RLC, the CU may not notify the parameters with the same value also used in the mobile target beam / TRP. Therefore, the signaling amount generated by the parameter notification can be reduced.

[0606] Similar to Embodiment 4, when the beam / TRP of the UE is switched, the CU and the UE can restore the value of the RRC parameters related to the RLC to the initial value or can maintain it. This initial value can be determined by the standard or can be notified from the CU to the UE using RRC signaling. Whether to restore the initial value or maintain it as described above can be determined by the standard, can be notified from the CU to the UE in advance, or can be notified from the CU to the UE together with the handover indication. Thus, the same effect as in Embodiment 4 can be obtained.

[0607] Similar to Embodiment 4, the CU can notify the RRC parameters related to the RLC to the UE together with the handover indication, or can notify the handover indication after the notification of the RRC parameters related to the RLC. Alternatively, the CU can notify the RRC parameters related to the RLC after the notification of the handover indication. In this case, the CU can notify the handover indication together with the handover timing to the UE. Thus, the same effect as in Embodiment 4 can be obtained.

[0608] The CU can notify the above-mentioned RRC parameters related to the RLC to the UE using L1 / L2 signaling. Thus, the parameters can be notified to the UE quickly.

[0609] Alternatively, the CU can notify the above-mentioned RRC parameters related to the RLC using MAC signaling. Thus, multi-level modulation can be performed, and the parameters can be notified with fewer symbols. In addition, HARQ retransmission control is performed, so the reliability of the parameter notification is improved.

[0610] Similar to Embodiment 4, the mobile source TRP can notify the CU of information indicating that the parameter confirmation has been delivered. The above information can be notified when using MAC signaling for parameter notification. The CU can use the above information to notify the UE of the handover indication. Thereby, the malfunction of the RLC caused by the non-delivery of the parameter can be prevented.

[0611] Regarding the handover notification, similar to Embodiment 4, it can be notified from the CU to the UE using L1 / L2 signaling, or it can be notified from the CU to the UE using MAC signaling. Thereby, the same effect as in Embodiment 4 can be obtained.

[0612] Similar to Embodiment 4, the CU can send notifications of RLC-related parameters multiple times, increasing the transmission power. Thereby, the reliability of parameter notification can be improved. The same applies to the handover indication from the CU to the UE.

[0613] The CU and the UE can stop the transmission and reception of user data together with the notification of the handover indication. The CU and the UE can resume the transmission and reception of user data after the beam / TRP handover is completed. Thereby, the loss of data due to RLC re-establishment can be prevented.

[0614] By using this Modification 4, the RRC parameters related to the RLC can be quickly notified to the UE. In addition, since appropriate values can be set according to the transmission environment of the beam / TRP, the communication delay in the RLC layer is reduced and the reliability is improved.

[0615] Embodiment 5.

[0616] In Embodiment 4, it is shown that, for example, when the CU has PDCP and the DU has RLC, MAC, and PHY, or when the CU has PDCP and H-RLC and the DU has L-RLC, MAC, and PHY, the RRC parameters are notified from the mobile source beam / TRP to the UE. Regarding the above situation, the RRC parameters can also be notified from the mobile target beam / TRP to the UE.

[0617] The mobile target beam / TRP notifies the UE of the RRC parameters. The mobile source beam / TRP notifies the UE of the handover indication.

[0618] The notification of the RRC parameters from the mobile target beam / TRP to the UE can be performed after the handover notification from the mobile source beam / TRP to the UE. Thereby, the UE can smoothly obtain the RRC parameters after switching the communication target beam / TRP.

[0619] The RRC parameters can be the parameters shown in Section 6.3.2 of Non-Patent Document 12 in the same manner as in Embodiment 2. The RRC parameters can be, for example, parameters related to SR, parameters related to Ack / Nack repetition, parameters related to the Sounding Reference Signal (SRS), or parameters related to CQI / CSI.

[0620] Among the above, the RRC parameters related to SR can be the parameters shown in (1) to (3) in Embodiment 2. In addition, in the same manner as in Embodiment 2, the CU may or may not notify the UE of the parameter indicating the maximum number of retransmissions of SR as an RRC parameter related to SR. Thus, the same effect as in Embodiment 2 can be obtained.

[0621] The CU can notify the UE of the parameters required for beam scanning. The parameters required for beam scanning can be set as the parameters shown in Embodiment 1. The notification of the parameters required for scanning the beam can be performed via the mobile source beam / TRP. The parameters required for beam scanning can be set as the parameters in the mobile target beam / TRP. Thus, the UE can easily receive the beam scanning signal during the movement between beams / TRPs.

[0622] Notifying the RRC parameters from the mobile target beam / TRP to the UE can use L1 / L2 signaling in the same manner as in Embodiment 2, or can use MAC signaling. Thus, the parameters required for beam speed scanning can be notified quickly.

[0623] Alternatively, among the above, RRC signaling can be used in the same manner as in Embodiment 3. Thus, the RRC parameters can be notified from the CU to the UE in advance, so there is no need to notify the RRC parameters during beam / TRP switching. Thus, the signaling amount can be reduced.

[0624] The method of notifying the handover indication from the mobile source beam / TRP to the UE can use L1 / L2 signaling in the same manner as in Embodiment 2, or can use MAC signaling. Thus, the beam / TRP handover can be notified to the UE quickly. In addition, by using MAC signaling, the reliability of the above notification can be improved.

[0625] In the same manner as in Embodiment 4, the mobile source TRP can notify the CU of the information indicating that the handover indication has been confirmed to be delivered. The above information can be notified when MAC signaling is used for the notification of the handover indication. The CU can use the above information to switch the beam / TRP. Thus, the beam / TRP switching when the handover indication is not delivered can be prevented, so the RLF caused by the loss of the link between the UE and the CU can be avoided.

[0626] Regarding RRC parameters, the CU may also not notify the same parameter values in the mobile target beam / TRP. Therefore, the signaling volume generated by parameter notification can be reduced.

[0627] In the above notification of the handover indication using MAC signaling, similar to Embodiment 2, the CU may switch the beam / TRP when the handover indication from the mobile source beam / TRP to the UE exceeds the HARQ retransmission count. The beam / TRP can be switched when it is impossible to determine the Ack / Nack of the UE for the handover indication. Thus, when the mobile source beam / TRP fails to receive the Ack signal from the UE for the handover indication, the communication target beam / TRP in the UE can be switched and the beam / TRP in the gNB can also be switched. Thereby, the loss of connection between the UE and the gNB can be prevented.

[0628] Similar to Embodiment 2, the UE may send an uplink signal to the beam / TRP of the mobile source. The uplink signal may be a response to the L1 / L2 signaling for the handover indication from the CU. As the uplink signal, L1 / L2 signaling for response may be newly set. As the above response, new uplink control information (UCI) may be set. Thereby, the same effect as that described in Embodiment 2 can be obtained.

[0629] For the new UCI, it may be set the same as in Embodiment 2. Thereby, the same effect as that in Embodiment 2 can be obtained.

[0630] In the above, similar to Embodiment 4, the mobile source beam / TRP may notify the CU of the information indicating that the L1 / L2 signaling for response has been received. Thereby, the CU can grasp the situation that the UE has correctly received the handover indication, and thus, the beam / TRP switching can be smoothly performed.

[0631] Regarding the notification of the handover indication using MAC signaling from the mobile source beam / TRP to the UE, the mobile source beam / TRP may notify the CU of the information indicating that an Ack has been received for the notification of the handover indication. The CU may switch the used beam / TRP using the notified information. Thereby, the CU can grasp the situation that the UE has correctly received the handover indication, and thus, the beam / TRP switching can be smoothly performed.

[0632] Similar to Embodiment 2, the UE can send an uplink signal to the beam / TRP of the mobile target. The uplink signal can be set as a signal for confirming beam / TRP switching in the UE. The frequency resources of the SR can be used to send the confirmation signal. Alternatively, the SR can be sent as the confirmation signal. Thus, when the mobile target beam / TRP confirms that the communication target beam / TRP of the UE has been switched, it can notify the RRC parameters. Thus, the reliability of delivering the RRC parameter notification to the UE can be improved.

[0633] The SR transmission from the UE to the mobile target beam / TRP, the common resources for the SR, and the SRS transmission are the same as those in Embodiment 2, so the description is omitted.

[0634] Regarding the CU's judgment on whether there is a communication target beam / TRP switch in the UE, it is the same as that in Embodiment 2, so the description is omitted.

[0635] The transmitting source beam / TRP can send the handover indication notification to the UE multiple times or increase the power. Thus, the reliability of the handover indication notification can be improved.

[0636] The transmitting target beam / TRP can notify the parameters to the UE multiple times or increase the power. Thus, the reliability of the above parameter notification can be improved.

[0637] For the SR transmission from the UE, the mobile source beam / TRP can invalidate the SR received by the UE. When a beam / TRP switch occurs between SR reception and uplink scheduling grant transmission, the mobile source beam / TRP can invalidate the SR. In the above, the UE can retransmit the SR to the mobile target beam / TRP. The retransmission of the SR from the UE can be performed after receiving the RRC parameters related to the SR from the mobile target beam / TRP. Thus, the situation where the retransmitted SR sent from the UE to the mobile target beam / TRP fails to reach the mobile target beam / TRP can be avoided.

[0638] Alternatively, in the above, the mobile source beam / TRP can make the SR received from the UE valid. The mobile source beam / TRP can forward the SR to the mobile target beam / TRP. This forwarding can be via the CU. In the above, the information indicating the reception of the SR can be used instead of the SR. Thus, even when a beam / TRP switch occurs between SR reception and uplink scheduling grant transmission, a series of processes including SR transmission, uplink scheduling grant reception, and uplink user data reception can proceed smoothly in the UE. Thus, the uplink scheduling grant can be received and the uplink user data can be transmitted without waiting for the RRC parameters related to the SR to be notified by the mobile target beam / TRP. Thus, the delay in uplink user data communication can be reduced.

[0639] The mobile target beam / TRP can simultaneously notify the UE of the uplink scheduling grant and the RRC parameters related to the SR. Thereby, the signaling amount from the mobile target beam / TRP to the UE can be reduced, and the delay in the uplink user data communication can be decreased.

[0640] Regarding the uplink scheduling grant notification from the CU to the UE, the CU and the UE can invalidate the uplink scheduling grant sent from the mobile source beam / TRP. When a beam / TRP handover occurs between the uplink scheduling grant and the uplink user data, the CU and the UE can invalidate the uplink scheduling grant. Among the above, the mobile target beam / TRP can retransmit the uplink scheduling grant to the UE. In the retransmission of the uplink scheduling grant, the mobile source beam / TRP can request the mobile target beam / TRP to retransmit the uplink scheduling grant to the UE. Alternatively, the UE can restart the SR transmission to the mobile target beam / TRP. The retransmission of the SR can be performed after receiving the RRC parameter notification from the CU to the UE. Thereby, the situation where the retransmitted SR from the UE fails to reach the CU can be prevented.

[0641] Regarding whether the UE restarts the SR transmission as described above, it can be determined by a standard or notified by the CU to the UE. The notification from the gNB to the UE can be preformed by RRC signaling, can be preformed by MAC signaling, or can be preformed by L1 / L2 signaling. In an example where the above notification is preformed by MAC signaling or L1 / L2 signaling, the above notification can be performed together with the handover notification. Thereby, the UE can receive the uplink scheduling grant corresponding to the uplink resource usage status of the mobile target beam / TRP for the uplink user data transmission.

[0642] Alternatively, regarding the beam / TRP handover after the uplink scheduling grant notification from the mobile source beam / TRP to the UE, the CU and the UE can make the uplink scheduling grant sent from the mobile source beam / TRP valid. The UE can use the uplink scheduling grant to send uplink user data to the mobile target beam / TRP. Thereby, the signaling amount between the CU and the UE can be reduced.

[0643] Whether the above-mentioned uplink scheduling grant is set to be valid can be determined by a standard, or it can be notified from the CU to the UE. The notification from the gNB to the UE can be preformed by RRC signaling, by MAC signaling, or by L1 / L2 signaling. As an example of the case where the uplink scheduling grant is set to be valid, it can be set to the case where the mobile target beam / TRP can use the uplink resources indicated by the scheduling grant for this UE. The mobile source beam / TRP can notify the mobile target beam / TRP of information about the uplink scheduling grant. Thereby, the mobile target beam / TRP can determine whether the uplink scheduling grant is valid or invalid, and thus flexible scheduling can be achieved.

[0644] In an example where the above-mentioned notification is performed by MAC signaling or L1 / L2 signaling, the above-mentioned notification can be performed together with the handover notification. Thereby, the CU can perform scheduling corresponding to the uplink resource usage status in the mobile target beam / TRP with less signaling.

[0645] For the uplink user data transmission from the UE to the CU, the mobile target beam / TRP can send an Ack / Nack of the mobile source beam / TRP for the uplink user data received from the UE to the UE. The above-mentioned Ack / Nack transmission from the mobile target beam / TRP to the UE can be performed when a beam / TRP handover occurs between the uplink user data transmission from the UE and the Ack / Nack notification for the uplink user data. In the above, the mobile source beam / TRP can notify the mobile target beam / TRP of information indicating the Ack / Nack for the uplink user data. Thereby, the beam / TRP handover after the uplink user data transmission can be smoothly performed.

[0646] The mobile source beam / TRP can notify the mobile target beam / TRP of information related to the decoding result of the uplink user data received from the UE. This information can be, for example, the soft decision value of the uplink user data. Thereby, the mobile target beam / TRP can combine and decode the first reception result and the retransmission reception result of the uplink user data. Thereby, the probability of reception error can be reduced.

[0647] According to the fifth embodiment, the same effects as those of the second embodiment can also be obtained when the CU has PDCP, the DU has RLC, MAC, and PHY, or when the CU has PDCP and H-RLC, and the DU has L-RLC, MAC, and PHY. In addition, even when the communication environment between the mobile source beam / TRP and the UE deteriorates rapidly, the RRC parameters can be notified from the CU to the UE. As a result, for example, the random access process of the UE caused by the non-delivery of the SR can be suppressed.

[0648] Similar to the combination of Embodiment 2 and Embodiment 3, Embodiment 4 and this Embodiment 5 can also be used in combination. That is, the CU can switch which of the mobile source beam / TRP and the mobile target beam / TRP to send the RRC parameters from. Thus, the CU can flexibly change the beam / TRP for sending the RRC parameters according to the communication environment.

[0649] Similar to the combination of Embodiment 2 and Embodiment 3, regarding which of the mobile source beam / TRP and the mobile target beam / TRP to send the RRC parameters from, the CU can be set for the UE quasi-statically in advance, can be set dynamically by the CU, or can be implicitly determined by the standard. Thus, the same effect as the combination of Embodiment 2 and Embodiment 3 can be obtained.

[0650] In Embodiment 5, a base station device with the CU and DU separated is shown as an example, but it can also be applied to a base station device without the CU and DU separated. This base station device can be a base station device that does not share RRC parameters between beams. In addition, this base station device can be, for example, a base station that performs different HARQ scheduling for each beam, a base station that has different RLC layers for each beam, or a base station that combines both of the above. When applying Embodiment 5 to this base station device, the gNB can be used to replace the CU. Thus, during the movement between beams within the cell, the RRC parameters can be notified to the UE from the gNB via the mobile target beam, and the number of UEs accommodated in the cell spatially separated by the beams can be increased. The parameters can be notified from the gNB to the UE quickly.

[0651] According to Embodiment 5, similar to Embodiment 2, the following communication system is provided. This communication system includes, for example, a communication terminal device, a base station device that performs wireless communication with the communication terminal device using a wireless beam. The cell formed by the base station device is spatially separated by a plurality of wireless beams under the base station device. When the communication terminal device moves from the coverage range of the first wireless beam to the coverage range of the second wireless beam, the base station device changes the RRC (Radio Resource Control) parameters used for the communication terminal device from the first RRC parameters for the first wireless beam to the second RRC parameters for the second wireless beam. In addition, the plurality of wireless beams can be formed by a plurality of DUs (in other words, TRPs) as Figure 8 illustrated, can be formed by one DU, or can be formed by a base station device that integrates the CU and DU.

[0652] According to this structure, the RRC parameters used for the communication terminal device are changed according to the change of the wireless beam used for the communication terminal device. Therefore, the number of communication terminal devices that can be accommodated can be increased as described above.

[0653] Here, the above structure can be variously deformed as described above. Particularly according to Embodiment 5, for example, the following communication system is provided: that is, the base station device includes at least one DU (Distributed Unit) that outputs a plurality of wireless beams and a CU (Central Unit) that controls at least one DU. At least one DU has a MAC (Medium Access Control) function. The base station device notifies the communication terminal device of the second RRC parameter via the second wireless beam using L1 / L2 signaling or MAC signaling, and notifies the communication terminal device of the handover instruction from the first wireless beam to the second wireless beam via the first wireless beam using L1 / L2 signaling or MAC signaling. In the above, the DU may have an RLC (Radio Link Control) function. In addition, as another example, the following communication system is provided: that is, the base station device has a function of outputting a plurality of wireless beams and a MAC function. The base station device notifies the communication terminal device of the second RRC parameter using the second wireless beam, and notifies the communication terminal device of the handover instruction from the first wireless beam to the second wireless beam using the first wireless beam.

[0654] In addition, various deformations are provided as described in the following Modification Examples 1 to 4.

[0655] Modification Example 1 of Embodiment 5.

[0656] In Embodiment 5, the description is centered on the notification of RRC parameters related to SR, but it can also be applied to RRC parameters related to Ack / Nack repetition.

[0657] The above RRC parameters related to Ack / Nack repetition can be the same as those in Modification Example 1 of Embodiment 2.

[0658] In this Modification Example 1, the method and content of the handover notification notified by the CU to the UE via the pre-movement beam / TRP can be set to be the same as those in Embodiment 5. In addition, the method of notifying the RRC parameter notification related to Ack / Nack repetition by the CU to the UE via the target movement beam / TRP can be applied to the same method as the RRC parameter notification described in Embodiment 5. Thus, the same effect as that of Embodiment 5 can be obtained.

[0659] Similar to Embodiment 5, the CU can notify the UE of the parameters required for beam scanning. The method of notifying the parameters can be the same as that in Embodiment 5. Thus, the UE can easily receive the beam scanning signal during the movement between beams / TRPs.

[0660] The above notification of the parameters required for beam scanning from the CU to the UE can use L1 / L2 signaling or MAC signaling. Thus, the same effect as that of Embodiment 5 can be obtained.

[0661] Similar to Embodiment 5, regarding the RRC parameters related to Ack / Nack repetition, the CU may also not notify the parameters that use the same values in the mobile target beam / TRP. Therefore, the signaling volume generated by parameter notification can be reduced.

[0662] Similar to Embodiment 5, the CU and the UE may restore the value of the RRC parameter related to Ack / Nack repetition to the initial value when the beam / TRP of the UE is switched, or may hold it. Whether to restore the value of the parameter at the time of beam / TRP switching of the UE to the initial value or hold it can be determined by the standard, or can be notified from the CU to the UE in advance. Alternatively, the information indicating whether to return to the initial value or hold it can be notified from the CU to the UE together with the handover indication. Thus, even when the parameter notification from the mobile source beam / TRP to the UE fails, the UE can use the initial value or the RRC parameter before the change, so the reliability of Ack / Nack repetition from the UE to the mobile target beam / TRP can be improved.

[0663] The CU can notify the UE of the above-mentioned RRC parameters related to Ack / Nack repetition by using L1 / L2 signaling. Thus, the parameters can be notified to the UE quickly.

[0664] Alternatively, the CU can notify the above-mentioned RRC parameters related to Ack / Nack repetition by using MAC signaling. Thus, multilevel modulation can be performed, so the parameters can be notified with fewer symbols. In addition, HARQ retransmission control is performed, so the reliability of parameter notification is improved.

[0665] Regarding the handover notification, similar to Embodiment 2, it can be notified from the CU to the UE by using L1 / L2 signaling, or can be notified from the CU to the UE by using MAC signaling. Thus, the same effect as in Embodiment 2 can be obtained.

[0666] The method of notifying the handover indication from the mobile source beam / TRP to the UE can use L1 / L2 signaling in the same way as in Embodiment 5, or can use MAC signaling. Thus, the same effect as that shown in Embodiment 5 can be obtained.

[0667] Similar to Embodiment 5, the mobile source TRP can notify the CU of the information indicating that the handover indication has been confirmed to be delivered. The above-mentioned information can be notified when MAC signaling is used for the notification of the handover indication. The CU can switch the beam / TRP by using the above-mentioned information. Thus, the beam / TRP switching when the handover indication is not delivered can be prevented, so the RLF caused by the UE losing the link with the gNB can be avoided.

[0668] Similarly to Embodiment 5, the CU can send the UE notifications of parameters related to Ack / Nack repetition multiple times, which can increase the transmission power. As a result, the reliability of the notifications of Ack / Nack repetition can be improved. The same applies to the handover indication from the CU to the UE.

[0669] For both the mobile source beam / TRP and the mobile target beam / TRP, the UE may not notify Ack / Nack for the downlink user data received from the CU via the mobile source beam / TRP. The above UE operation can be performed when a beam / TRP handover occurs between the downlink user data and the Ack / Nack. The mobile source beam / TRP may forward the above downlink user data to the mobile target beam / TRP. The mobile target beam / TRP may forward the above downlink user data to the UE. As a result, it is possible to prevent the loss of downlink user data due to beam / TRP handover.

[0670] As another example, the UE may notify the mobile target beam / TRP of the Ack / Nack for the downlink user data received from the CU via the mobile source beam / TRP. The above Ack / Nack notification can be performed when a beam / TRP handover occurs between the downlink user data and the Ack / Nack. The mobile target beam / TRP may notify the mobile source beam / TRP of the above Ack / Nack reception result. As a result, the signaling amount related to the downlink user data when a beam / TRP handover occurs can be reduced.

[0671] In the above, the mobile source beam / TRP may forward the above downlink user data to the mobile target beam / TRP. The above forwarding can be performed when a Nack notification for the downlink user data is received from the UE. The mobile target beam / TRP may retransmit the downlink user data to the UE using the forwarded downlink user data. As a result, the retransmission process of the downlink user data during beam / TRP handover can be smoothly performed.

[0672] After receiving the parameter notification related to Ack / Nack repetition from the CU to the UE, the retransmission of the downlink user data from the mobile target beam / TRP to the UE can be performed. As a result, the mobile target beam / TRP can receive the Ack / Nack after the second time set by the Ack / Nack repetition, and thus the reliability of the Ack / Nack notification from the UE to the mobile target beam / TRP can be improved.

[0673] The notification of Ack / Nack from the UE to the mobile target beam / TRP can be performed after receiving the parameter notification related to Ack / Nack repetition from the mobile target beam / TRP to the UE, similarly to the above. As a result, the same effect as above can be obtained.

[0674] Regarding the determination of the Ack / Nack received from the UE, the mobile source beam / TRP can utilize only the reception result in this beam / TRP, or can also utilize the reception result in the mobile target beam / TRP. The mobile target beam / TRP can transfer the Ack / Nack reception result from the UE to the mobile source beam / TRP. The above actions can be performed when the beam / TRP is switched during the Ack / Nack repetition from the UE to the mobile source beam / TRP. By only utilizing the reception result in the mobile source beam / TRP, the reception action of the Ack / Nack repetition from the UE can be performed quickly. By also utilizing the reception result in the mobile target beam / TRP, the reliability of the Ack / Nack repetition in the mobile source beam / TRP can be improved. Regarding whether the mobile source beam / TRP only utilizes the reception result in this beam / TRP or also utilizes the reception result in the mobile target beam / TRP, it can be determined by the standard or can be appropriately switched by the CU. By appropriately switching by the CU, for example, an appropriate reception action can be selected according to the transmission status in the mobile source beam / TRP, so the flexibility of the reception process of the Ack / Nack repetition in the gNB can be improved.

[0675] In the above, the mobile target beam / TRP can replace the mobile source beam / TRP to perform the reception process of the Ack / Nack repetition. The mobile target beam / TRP can utilize only the reception result in this beam / TRP, or can also utilize the reception result in the mobile source beam / TRP. The mobile source beam / TRP can transfer the Ack / Nack reception result from the UE to the mobile target beam / TRP. Thereby, the same effect as above can be obtained. Regarding whether the mobile target beam / TRP only utilizes the reception result in this beam / TRP or also utilizes the reception result in the mobile source beam / TRP, it can be determined by the standard or can be appropriately switched by the CU.

[0676] In the above, which one of the mobile source beam / TRP and the mobile target beam / TRP performs the Ack / Nack reception action can be determined by the standard or can be pre-determined by the CU. Thereby, malfunction caused by the incoordination of the reception results of the Ack / Nack between the mobile source beam / TRP and the mobile target beam / TRP can be prevented.

[0677] The mobile target beam / TRP can use the Ack / Nack repetition sent from the UE to the mobile source beam / TRP to retransmit the downlink user data to the UE. This retransmission can be performed when the beam / TRP is switched between the Ack / Nack repetition from the UE to the mobile source beam / TRP and the retransmission of the downlink user data to the UE. The mobile source beam / TRP can transfer the retransmitted data to the mobile target beam / TRP. Thereby, the downlink user data retransmission process at the time of beam / TRP switching can be smoothly performed.

[0678] By using this Modification Example 1, the same effect as that of Embodiment 5 can be obtained regarding the notification of the RRC parameters related to the Ack / Nack repetition to the UE.

[0679] Modification Example 2 of Embodiment 5.

[0680] In Embodiment 5, the description is centered on the notification of the RRC parameters related to the SR, but it can also be applied to the RRC parameters related to the SRS.

[0681] The above-mentioned RRC parameters related to the SRS can be the same as those in Modification Example 2 of Embodiment 2.

[0682] In this Modification Example 2, the method and content of the handover notification notified by the CU to the UE via the mobile pre-beam / TRP can be set to be the same as those in Embodiment 5. In addition, the method of notifying the RRC parameters related to the SRS from the CU to the UE via the mobile target beam / TRP can be applied to the same method as the RRC parameter notification described in Embodiment 5. Thereby, the same effect as that of Embodiment 5 can be obtained.

[0683] Similar to Embodiment 5, the CU can notify the UE of the parameters required for beam scanning. Thereby, the UE can easily receive the beam scanning signal during the movement between the beams / TRPs.

[0684] The above-mentioned notification of the parameters required for beam scanning from the CU to the UE can use L1 / L2 signaling or MAC signaling. Thereby, the same effect as that of Embodiment 5 can be obtained.

[0685] Similar to Embodiment 5, regarding the RRC parameters related to the SRS, the CU may not notify the parameters that use the same values in the mobile target beam / TRP. Therefore, the signaling amount generated by the parameter notification can be reduced.

[0686] Similar to Embodiment 5, the CU and the UE can restore the value of the RRC parameter related to the SRS to the initial value when the beam / TRP of the UE is switched, or can hold it. Whether to restore the value of the parameter at the time of beam / TRP switching of the UE to the initial value or hold it can be determined by the standard, or can be notified from the CU to the UE in advance. Alternatively, information on whether to restore the initial value or hold it can be notified from the CU to the UE together with the handover indication. Thereby, the same effect as in Embodiment 5 can be obtained.

[0687] The CU can notify the above-mentioned RRC parameter related to the SRS to the UE by using L1 / L2 signaling. Thereby, the parameter can be quickly notified to the UE.

[0688] Alternatively, the CU can notify the above-mentioned RRC parameter related to the SRS by using MAC signaling. Thereby, multi-level modulation can be performed, so the parameter can be notified with a smaller number of symbols. In addition, HARQ retransmission control is performed, so the reliability of parameter notification is improved.

[0689] Regarding the handover notification, similar to Embodiment 5, it can be notified from the CU to the UE by using L1 / L2 signaling, or can be notified from the CU to the UE by using MAC signaling. Thereby, the same effect as in Embodiment 5 can be obtained.

[0690] Similar to Embodiment 5, the CU can send notifications of parameters related to the SRS to the UE multiple times, and can increase the transmission power. Thereby, the reliability of parameter notification related to the SRS can be improved. The same applies to the handover indication from the CU to the UE.

[0691] The UE can perform SRS transmission to the mobile target beam / TRP after receiving the parameter related to the SRS sent from the CU via the mobile target beam / TRP. Thereby, it is possible to suppress the SRS that cannot be received by the mobile target beam / TRP from being transmitted in the UE before receiving the parameter related to the SRS.

[0692] The UE can perform SRS transmission for the SRS transmission indication received from the mobile source beam / TRP to the mobile target beam / TRP. The above-mentioned SRS transmission from the UE to the mobile target beam / TRP can be performed when a beam / TRP switch occurs between the SRS transmission indication and the SRS transmission. The above-mentioned SRS transmission can be an aperiodic SRS transmission. The mobile source beam / TRP can notify the mobile target beam / TRP of the situation where the SRS transmission has been indicated to the UE. Thereby, the SRS transmission process at the time of beam / TRP switching can be smoothly performed in the CU and the UE.

[0693] In the above, the UE can invalidate the SRS transmission indication received from the mobile source beam / TRP. Thereby, the signaling from the mobile source beam / TRP to the mobile target beam / TRP can be reduced.

[0694] The mobile source beam / TRP can invalidate the SRS transmitted from the UE to this beam. The action of invalidating the SRS can be performed when the beam / TRP is switched after the SRS is transmitted. Thereby, the mobile target beam / TRP can perform scheduling adapted to the transmission status after the beam / TRP is switched.

[0695] By using this Modification Example 2, the same effect as in Embodiment 5 can be obtained for the notification of RRC parameters related to the SRS to the UE.

[0696] Modification Example 3 of Embodiment 5.

[0697] In Embodiment 5, the description is centered on the notification of RRC parameters related to the SR, but it can also be applied to RRC parameters related to the CQI / CSI.

[0698] The above RRC parameters related to the CQI / CSI can be the same as those in Modification Example 3 of Embodiment 2.

[0699] In this Modification Example 3, the method and content of the handover notification notified by the CU to the UE via the pre-movement beam / TRP can be set to be the same as those in Embodiment 5. In addition, the method of notifying the RRC parameter notification related to the CQI / CSI from the CU to the UE via the mobile target beam / TRP can be applied to the same method as the RRC parameter notification described in Embodiment 5. Thereby, the same effect as in Embodiment 5 can be obtained.

[0700] Similar to Embodiment 5, the CU can notify the UE of the parameters required for beam scanning. Thereby, the UE can easily receive the beam scanning signal during the movement between the beams / TRPs.

[0701] The above notification of the parameters required for beam scanning from the CU to the UE can use L1 / L2 signaling or MAC signaling. Thereby, the same effect as in Embodiment 5 can be obtained.

[0702] Similar to Embodiment 5, regarding the RRC parameters related to the CQI / CSI, the CU can refrain from notifying the parameters that use the same values even in the mobile target beam / TRP. Therefore, the signaling amount generated by the parameter notification can be reduced.

[0703] Similar to Embodiment 5, the CU and the UE can restore the values of the RRC parameters related to CQI / CSI to their initial values or maintain them when the beam / TRP of the UE is switched. Whether to restore the values of the parameters at the time of beam / TRP switching of the UE to their initial values or maintain them can be determined by the standard or notified to the UE from the CU in advance. Alternatively, information indicating whether to restore to the initial values or maintain them can be notified from the CU to the UE together with the handover indication. Thereby, the same effects as in Embodiment 5 can be obtained.

[0704] The CU can notify the UE of the above-mentioned RRC parameters related to CQI / CSI by using L1 / L2 signaling. Thereby, the parameters can be notified to the UE quickly.

[0705] Alternatively, the CU can notify the above-mentioned RRC parameters related to CQI / CSI by using MAC signaling. Thereby, multi-level modulation can be performed, so that the parameters can be notified with a smaller number of symbols. In addition, HARQ retransmission control is performed, so that the reliability of parameter notification is improved.

[0706] Regarding the handover notification, similar to Embodiment 5, it can be notified from the CU to the UE by using L1 / L2 signaling or by using MAC signaling from the CU to the UE. Thereby, the same effects as in Embodiment 5 can be obtained.

[0707] Similar to Embodiment 5, the CU can send notifications of the parameters related to CQI / CSI to the UE multiple times to increase the transmission power. Thereby, the reliability of the parameter notification related to CQI / CSI can be improved. The same applies to the handover indication from the CU to the UE.

[0708] The UE can perform CQI / CSI transmission to the mobile target beam / TRP after receiving the parameters related to CQI / CSI sent from the CU via the mobile target beam / TRP. Thereby, it is possible to suppress the transmission of CQI / CSI that cannot be received by the mobile target beam / TRP before the UE receives the parameters related to CQI / CSI.

[0709] The UE can perform CQI / CSI transmission for a mobile target beam / TRP to send an indication for the CQI / CSI received from the mobile source beam / TRP. The above CQI / CSI transmission from the UE to the mobile target beam / TRP can be performed when a beam / TRP handover occurs between the CQI / CSI transmission indication and the CQI / CSI transmission. The above CQI / CSI transmission can be an aperiodic CQI / CSI transmission. The mobile source beam / TRP can notify the mobile target beam / TRP of information indicating that a CQI / CSI transmission indication has been made for the UE. Thereby, the CQI / CSI transmission process can be smoothly performed among the mobile source beam / TRP, the mobile target beam / TRP, and the UE when a beam / TRP handover occurs.

[0710] The mobile source beam / TRP can invalidate the CQI / CSI sent from the UE to this beam. The action of invalidating the CQI / CSI can be performed when the beam / TRP is switched after the CQI / CSI transmission. The mobile source beam / TRP can notify the mobile target beam / TRP of information indicating that a CQI / CSI transmission indication has been made for the UE. The mobile target beam / TRP can retransmit the CQI / CSI transmission indication to the UE. The UE can retransmit the CQI / CSI to the mobile target beam / TRP. Thereby, the mobile target beam / TRP can perform scheduling adapted to the transmission status after the beam / TRP handover.

[0711] By using this Modification Example 3, the same effect as that of Embodiment 5 can be obtained regarding the notification of RRC parameters related to CQI / CSI to the UE.

[0712] Modification Example 4 of Embodiment 5.

[0713] In Embodiment 5, the description is centered on the notification of RRC parameters related to SR, but it can also be applied to RRC parameters related to RLC.

[0714] In the above, (1) to (8) shown in Modification Example 4 of Embodiment 4 can be used as RRC parameters related to RLC.

[0715] In this Modification Example 4, the method and content of the handover notification notified by the CU to the UE via the pre-movement beam / TRP can be set to be the same as those in Embodiment 5. In addition, the method of notifying the RRC parameters related to RLC by the CU to the UE via the pre-movement beam / TRP can be applied to the same method of RRC parameter notification described in Embodiment 5. Thereby, the same effect as that of Embodiment 5 can be obtained.

[0716] Similarly to Embodiment 5, the CU can notify the UE of the parameters required for beam scanning. The method of notifying the parameters can be the same as that in Embodiment 5. Thus, the same effects as those in Embodiment 5 can be obtained.

[0717] The notification of the parameters required for beam scanning from the CU to the UE can use L1 / L2 signaling or MAC signaling. Thus, the same effects as those in Embodiment 5 can be obtained.

[0718] Similarly to Embodiment 5, in the notification of RRC parameters related to RLC by the CU to the UE, an identifier indicating the parameter switch caused by TRP / beam switching can be included. The UE can maintain the RRC parameters related to RLC before the change, or can use the changed parameters after the TRP / beam switching. Thus, before the TRP / beam switching, the RLC reconstruction of the UE and the mobile source beam / TRP accompanied by the change of the RRC parameters related to RLC can be prevented, and the communication loss caused thereby can be prevented.

[0719] Similarly to Embodiment 5, regarding the RRC parameters related to RLC, the CU may not notify the parameters that use the same value even in the mobile target beam / TRP. Therefore, the signaling amount generated by parameter notification can be reduced.

[0720] Similarly to Embodiment 5, when the beam / TRP of the UE is switched by the CU and the UE, the value of the RRC parameter related to RLC can be restored to the initial value or can be maintained. The initial value can be determined by a standard or can be notified from the CU to the UE using RRC signaling. Whether to restore the initial value or maintain it as described above can be determined by a standard, can be notified from the CU to the UE in advance, or can be notified from the CU to the UE together with the handover indication. Thus, the same effects as those in Embodiment 5 can be obtained.

[0721] The CU can notify the UE of the above-mentioned RRC parameters related to RLC using L1 / L2 signaling. Thus, the parameters can be notified to the UE quickly.

[0722] Alternatively, the CU can notify the above-mentioned RRC parameters related to RLC using MAC signaling. Thus, multi-level modulation can be performed, so the parameters can be notified with fewer symbols. In addition, HARQ retransmission control is performed, so the reliability of parameter notification is improved.

[0723] Similarly to Embodiment 5, the mobile target TRP can notify the CU of the information indicating that the parameter confirmation has been delivered. The above information can be notified when MAC signaling is used for parameter notification. The CU can use the above information to notify the UE of the handover indication. Thus, the malfunction of the RLC caused by the non-delivery of the parameters can be prevented.

[0724] Regarding the handover notification, similar to Embodiment 5, the CU can notify the UE using L1 / L2 signaling, or the CU can notify the UE using MAC signaling. Thus, the same effect as in Embodiment 5 can be obtained.

[0725] Similar to Embodiment 5, the CU can send notifications of RLC-related parameters multiple times, which can increase the transmission power. Thus, the reliability of parameter notification can be improved. The same applies to the handover indication from the CU to the UE.

[0726] The CU and the UE can stop the transmission and reception of user data together with the notification of the handover indication. The CU and the UE can resume the transmission and reception of user data after the beam / TRP handover and the RLC-related parameter transmission and reception are completed. Thus, data loss due to RLC re-establishment can be prevented.

[0727] By using this Modification 4, the same effect as in Embodiment 5 can be obtained regarding the notification of RRC parameters related to RLC to the UE.

[0728] Embodiment 6.

[0729] There is a technology called carrier aggregation (CA) that collects multiple carriers and uses them as wireless resources for communication. In CA, for one UE, a serving cell composed of one PCell and one or more SCell is formed. Therefore, the CA setting is performed in units of cells. The CA setting from the eNB to the UE is performed by notifying the parameters of the CA cell unit.

[0730] In NR (New Radio), a technology is proposed in which a base station (in this specification, the 5G base station is called gNB) uses beamforming for communication, where beamforming uses multiple antennas to form a narrow-range beam. For example, in the gNB, the antenna 408 shown is composed of a multi-element antenna. Figure 4 The gNB forms a beam in a predetermined direction using a part or all of the multiple antennas of the multi-element antenna. By forming a narrow-range beam, the radio wave coverage range can be expanded.

[0731] When the cells performing CA support the operation of multiple beams, even if CA is set only by the cell identifier, it is not clear which beam of the cell can be aggregated. Therefore, the gNB cannot set CA for the UE and cannot use a lot of wireless resources. Therefore, high-speed and high-capacity communication services cannot be provided to the UE.

[0732] In this Embodiment 6, a method for solving the above problems is disclosed.

[0733] The CA setting is performed on a per-beam basis. One beam or multiple beams can be used. The gNB notifies the UE which beam to use when setting up the SCell.

[0734] Figure 12 This describes the architecture of CA set on a per-beam basis in the gNB. The gNB consists of protocols such as PDCP, RLC, MAC, and PHY. The PHY function can be split into two. These two PHY functions can be called H-PHY and L-PHY respectively.

[0735] In 3GPP, a scheme for separating the gNB into two units is proposed (refer to Non-Patent Document 7). These two units are called CU (Central Unit) and DU (Distributed Unit) respectively. Multiple DUs are connected to the CU. For example, a scheme is proposed where the CU has PDCP, RLC, MAC, and H-PHY. A scheme is proposed where the DU has L-PHY. The TRP can have the same function as the DU. Bn (n is a natural number) represents the beams that make up the set. The DU or TRP forms one or more beams.

[0736] The gNB performs CA on the UE through one PCC (Primary Component Carrier) and one or more SCCs (Secondary Component Carriers). The cell using the PCC is the PCell. The cell using the SCC is the SCell. Sometimes it is also presented as the gNB performing CA on the UE through one PCell and one or more SCells. Each cell independently has a HARQ at the lowest position in the MAC and aggregates above it. Each cell independently has functions below the PHY.

[0737] In the case of performing CA setting on a per-beam basis, it is set which beam within the PCell or SCell is used for CA. Figure 12 In the example, the gNB performs CA on the UE using beam 1 of TRP1 in the PCell, beam 2 of TRP2 in the PCell, beam 1 and beam 2 of TRP1 in the SCell, and beam 1 of TRP2 in the SCell.

[0738] By setting CA on a per-beam basis like this, a cell that supports beamforming can be set as the cell for CA. Therefore, a lot of radio resources can be used for the UE, enabling high-speed and high-capacity communication.

[0739] Disclose a method for CA setting in beam units.

[0740] Use RRC signaling in the CA setting of beam units. Set the beam-related information, and the gNB notifies the UE with RRC signaling. The beam-related information can be included in the message for SCell setting. For example, the beam-related information can be included in the RRC connection reset message. The beam-related information can be included in the parameters for SCell addition / change or SCell release.

[0741] The beam-related information is information that the UE can use to determine the beam. For example, when beam-specific RS is transmitted in a beam, the UE can determine the beam by receiving the beam-specific RS. In the above case, the beam-related information has the structure of beam-specific RS (Beam RS (BRS)). In addition, for example, when a beam is attached with an identifier and the beam identifier is associated with the beam-specific RS structure, the beam identifier can be set as the beam-related information. In addition, the renumbered beam index can be set according to the number of beams for which the beam identifier is set.

[0742] The gNB associates the above beam-related information with the SCell used for CA and notifies the UE. The gNB notifies the UE of the beam-related information regarding the beam that the UE monitors in the SCell. By receiving this information, the UE can identify the beam that it monitors in the SCell. The correspondence relationship between the SCell set by RRC and the beam is maintained until it is set again.

[0743] The gNB activates / deactivates the SCell for the UE using MAC control signaling. When the UE activates / deactivates the SCell using MAC control signaling, it is considered that the beam corresponding to the SCell received by using RRC signaling is activated / deactivated. The UE monitors the beam corresponding to the activated SCell. The UE detects whether there is information destined for this UE by monitoring the beam. For example, the UE receives the physical downlink control channel (PDCCH) of the beam and detects whether there is scheduling information destined for this UE.

[0744] The UE receives the SS (Synchronization Signal) of the SCell notified by RRC signaling and synchronizes. At this time, the SS is received and synchronized using any beam of the SCell. After synchronization, the UE detects the beam that it monitors in the SCell using at least one of the beam identifier and the BRS structure of the beam corresponding to the SCell notified by RRC signaling. The UE receives the physical downlink control channel (PDCCH) of the beam that it monitors.

[0745] As another method, the UE can receive the SS (Synchronization Signal) of the activated SCell notified by MAC control signaling and synchronize. At this time, any beam of the SCell is used to receive the SS and synchronize. After synchronization, the UE uses at least one of the beam identifier of the beam corresponding to the SCell notified by RRC signaling and the BRS structure to detect the beam to be monitored in the SCell. The UE receives the physical downlink control channel (PDCCH) of the beam to be monitored.

[0746] The gNB can use the PDCCH of this beam to notify the UE of scheduling information. Thus, the gNB can notify the UE of which beam to use for notification, and the UE can identify which beam to monitor and which beam to use for communication.

[0747] If only the SCell is notified as in the past, after accessing the SCell, it is necessary to set which beam in the SCell to use. Therefore, in addition to the process of accessing the SCell, it is also necessary to perform the process of selecting the beam to be used. Therefore, time is spent before the start of CA.

[0748] As shown in Embodiment 6 of the present invention, by determining which beam to use for CA when setting CA, the time until the start of CA can be reduced. Since CA can be started earlier, higher-capacity communication can be achieved.

[0749] In addition, as a method for the gNB to identify which beam to use for communication, the UE can measure each beam of the SCell in advance before CA setting. The UE can notify the gNB of the measurement result. This notification can be performed periodically, can be triggered according to an event, and can be performed according to the request of the gNB.

[0750] Figure 13 and Figure 14 is a diagram showing an example of a setting process of CA in units of beams using RRC signaling. Figure 13 and Figure 14 are connected at the position of the boundary line BL521. Figure 13 and Figure 14 show a case where the gNB performs CA on the UE using the PCell and the SCell. In addition, a case is shown where the PCell is composed of beam 1 and beam 2, and the SCell is composed of beam 1, beam 2, and beam 3. In step ST5201, the UE communicates with the gNB via beam 1 of the PCell.

[0751] In step ST5202, the gNB notifies the UE of the configuration information of the SCell for CA and the information related to the beam corresponding to the SCell through beam 1 of the PCell. RRC dedicated signaling is used in this notification. In conventional LTE, RRC dedicated signaling is used to notify the configuration information of the SCell for CA, so the information related to the beam can be added only in this message. The complexity of the control for the configuration of each beam can be suppressed.

[0752] In step ST5202, the beam notified corresponding to the SCell can be the beam used to notify the UE. The beam notified corresponding to the SCell can be the beam on which the UE wants to monitor the physical downlink control channel. The beam notified corresponding to the SCell can be the beam to which the UE wants to connect. Thereby, the gNB can notify the UE of which beam in the SCell is used for communication, and the UE can determine the beam used for communication in the SCell.

[0753] Each beam of the SCell periodically transmits SS (refer to steps ST5203 to ST5205). In addition, each beam of the SCell periodically transmits BRS (refer to steps ST5206 to ST5208). BRS can be transmitted according to at least one of the frequency and time resources of a predetermined pattern.

[0754] In step ST5209, the gNB notifies the activation / deactivation information of the SCell. MAC control signaling is used in this notification. The activation / deactivation information is notified in the MAC CE. In step ST5210, the UE receives the SS of the activated SCell and performs synchronization. In step ST5211, the UE detects the beam monitored in the SCell by using at least one of the beam identifier and the BRS structure of the beam corresponding to the SCell notified by the RRC dedicated signaling. In step ST5212, the UE receives the physical downlink control channel (PDCCH) of the monitored beam.

[0755] In step ST5213, the gNB that notified the activation information of the SCell through beam 1 of the PCell in step ST5209 notifies the UE of the downlink scheduling information from beam 1 of the SCell. This notification uses the L1 / L2 control signal. In step ST5214, the gNB transmits the downlink data to the UE according to this scheduling information. The UE receives the downlink data from beam 1 of the SCell in step ST5214 according to the scheduling information received from beam 1 of the SCell in step ST5213.

[0756] In step ST5215, the UE that wishes to perform uplink transmission via the SCell performs PRACH transmission using beam 1 of the SCell and conducts RA processing with the gNB. RA processing based on an indication of a Physical Downlink Control Channel (PDCCH) can be performed. In step ST5216, the UE starts to transmit uplink data on beam 1 of the SCell. The UE that wishes to perform uplink transmission via the SCell can transmit an SR instead of a PRACH. This is effective when uplink synchronization has been performed and there is no need to acquire the TA again, etc. When the gNB has recognized the existence of uplink data in the UE, the gNB notifies the UE of uplink scheduling information from beam 1 of the SCell. The UE transmits uplink data to the gNB according to this scheduling information.

[0757] PRACH transmission from the UE can be performed after detecting the beam through which the UE communicates. Here, PRACH transmission can be performed on the detected beam after the processing in step ST5211. Alternatively, PRACH transmission from the UE can be performed after receiving the PDCCH and before receiving the downlink scheduling information. Here, PRACH transmission can be performed on the detected beam after the processing in step ST5212. Uplink data transmission can be started earlier.

[0758] Next, refer to Figure 14 An example of the procedure when changing the beam through which the gNB and the UE communicate within the SCell is disclosed. In step ST5217, the gNB decides to change the beam through which it communicates with the UE. For example, it can be decided by the RRC functional unit of the gNB. As a method for deciding which beam to change the beam through which the gNB and the UE communicate to, the method disclosed above for the gNB to identify the beam through which it communicates can be applied. In step ST5218, the gNB notifies the UE of the setting information of the SCell for CA and the information related to the beam corresponding to this SCell through beam 1 of the PCell. The information related to the beam is set as the changed information. RRC dedicated signaling is used in this notification.

[0759] Although the case where the gNB notifies the UE of the setting information of the SCell for CA and the information related to the changed beam through beam 1 of the PCell is disclosed, it can also be notified through beam 1 of the SCell. The gNB can judge which communication quality is better and use the beam with better communication quality for notification.

[0760] In the case of notification through the beam of the PCell, it is not affected by a sharp deterioration in the communication quality of the beam of the SCell, and the gNB can notify the UE of the setting information of the SCell for CA and the information related to the changed beam. The UE can change to the beam notified by the gNB.

[0761] For example, in the case where the SCell is used with a high frequency and a narrow coverage area, the communication quality is likely to deteriorate sharply due to the blocking and movement of the UE. In the above case, the gNB can use the beam of the PCell for notification.

[0762] Each beam of the SCell periodically transmits an SS (refer to steps ST5219 to ST5221). In addition, each beam of the SCell periodically transmits a BRS (refer to steps ST5222 to ST5224). The BRS can be transmitted according to at least one of the frequency and time resources of a predetermined pattern.

[0763] In step ST5225, the gNB notifies the activation / deactivation information of the SCell. MAC control signaling is used in this notification. The activation / deactivation information is notified included in the MAC CE. If the activation / deactivation information of the SCell has not changed, this notification can be omitted. In step ST5226, the UE receives the SS of the activated SCell and performs synchronization. If the activated SCell has not changed and synchronization has already been performed, this process can be omitted.

[0764] In step ST5227, the UE detects the beam to be monitored within the SCell by using at least one of the beam identifier and the BRS structure of the changed beam corresponding to the SCell notified by the RRC dedicated signaling. In step ST5228, the UE receives the physical downlink control channel (PDCCH) of the beam to be monitored.

[0765] In step ST5229, the gNB notifies the downlink scheduling information to the UE from beam 2 of the SCell. This notification uses the L1 / L2 control signal. In step ST5230, the gNB transmits downlink data to the UE according to this scheduling information. The UE receives the downlink data from beam 2 of the SCell in step ST5230 according to the scheduling information received from beam 2 of the SCell in step ST5229.

[0766] In step ST5231, RA processing is performed between the UE that wishes to perform uplink transmission via the SCell and the gNB that performs PRACH transmission using beam 2 of the SCell. In step ST5232, the UE starts to transmit uplink data to beam 2 of the SCell. It is also possible to transmit an SR instead of a PRACH. This is effective in the case where uplink synchronization has been performed and there is no need to obtain TA again, etc. When the gNB has identified that uplink data exists in the UE, the gNB notifies the uplink scheduling information to the UE from beam 2 of the SCell. The UE transmits uplink data to the gNB according to this scheduling information.

[0767] Thus, the beam of the SCell communicating with the UE can be changed from beam 1 to beam 2.

[0768] Through the method disclosed in Embodiment 6, the gNB and the UE can determine the beam of the SCell and communicate. The gNB can set CA for the UE using the beam of the PCell and the beam of the SCell. The gNB can increase the radio resources used by setting CA for the UE. Therefore, high-speed and high-capacity communication services can be provided to the UE.

[0769] In addition, the UE does not need to perform the process of selecting the beam for communication after receiving the SS of the SCell. The UE does not need to notify the gNB of which beam of the SCell has been received. Therefore, the UE can determine the beam for communication earlier, and the additional process and correction process of the SCell can be performed with low latency.

[0770] According to Embodiment 6, the following communication system is provided. The communication system includes, for example, a communication terminal device and a base station device that performs wireless communication with the communication terminal device using a wireless beam. The cell formed by the base station device is spatially separated by a plurality of wireless beams subordinate to the base station device, and the base station device sets carrier aggregation in units of wireless beams. In addition, the plurality of wireless beams can be formed by a plurality of DUs (in other words, TRPs) as Figure 8 illustrated, or can be formed by one DU.

[0771] According to this structure, carrier aggregation is set in units of wireless beams. Therefore, a cell supporting beamforming can be used as a cell for carrier aggregation as described above, and the radio resources used can be increased. Thus, high-speed and high-capacity communication services can be provided.

[0772] Here, the above structure can be variously deformed as described above and as described in the following Modification Examples 1 to 2.

[0773] Modification Example 1 of Embodiment 6.

[0774] In NR, in order to ensure wideband frequency resources, it is necessary to operate in a high frequency band. In a high frequency band, the channel quality deteriorates rapidly due to blockage between the antenna of the gNB and the UE. In addition, the transmission loss becomes large in a high frequency band, so a beam with a narrow coverage range is used. When using a beam with a narrow coverage range, the beam will be frequently changed as the UE moves.

[0775] In the method disclosed in Embodiment 6, when the beam setting and change that the UE monitors during CA require RRC signaling. Therefore, the setting and change of the aggregated beams take time, and the delay before communicating with the desired beam becomes large. If the delay is large, the following situation will occur: the processing of beam setting and change due to blockage and UE movement will be too late, and the communication of the SCell cannot be continued.

[0776] In this Modification 1, a method for solving the above problems is disclosed.

[0777] The gNB notifies the UE of the beams that can form the SCell through RRC signaling. In Embodiment 6, the beams to be monitored by the UE are notified through RRC signaling. In this Modification 1, the beams that can form the SCell are notified. In other words, the gNB notifies the UE of the beams that can be configured as CA in the SCell that can be set as CA. This notification can be performed for each UE. The information related to the beam for communication can be the information related to the beam in Embodiment 6.

[0778] The gNB notifies the UE of the activation / deactivation information of the SCell through MAC signaling. The activation / deactivation information of the SCell notified through RRC signaling can also be notified.

[0779] Thus, the UE can identify which SCell to monitor. However, just by this, it is not clear which beam of the SCell can be used for communication.

[0780] The gNB notifies the UE of the activation / deactivation information of the beams that form the SCell through MAC signaling. The activation / deactivation information of the beams that form the activated SCell can be notified using MAC signaling. The information of the beam to be activated can be notified instead of the activation / deactivation information of the beams that form the SCell. The identification of the beam is the information of the beam.

[0781] In the case of changing the beam for CA, the activation / deactivation setting of the beam can be changed. The gNB can notify the UE of the activation / deactivation information of the changed beam. The activation / deactivation information of the beams that form the SCell can be set as MAC control information. The activation / deactivation information of the beams that form the activated SCell can be set.

[0782] The activation / deactivation information of the SCell and the activation / deactivation information of the beam can be used as one MAC CE. The amount of information can be reduced, and the processing of CA setting can be simplified.

[0783] The activation / deactivation information of the SCell and the activation / deactivation information of the beam can be used as different MAC CEs. In the setting for beam change within the SCell rather than in the CA setting, only the MAC CE for beam activation / deactivation is used. The amount of information during beam change can be reduced, and the beam change process can be simplified.

[0784] An example is disclosed in the case where the activation / deactivation information of the beam is used as the MAC CE. The maximum number of beams that can be formed by one cell can be determined in advance. Among the information related to the beams when notifying the beams formed by the SCell using RRC signaling, beam indices from 0 to the maximum value are provided for the beams formed by the SCell. In other words, numbering is performed. The beam index is associated with the beam ID and the BRS. For example, one cell can form a maximum of 7 beams. Beam indices from beam #0 to beam #6 are provided for the beams formed by the cell.

[0785] Figure 15 FIG. is an example of a MAC CE representing the activation / deactivation information of the beam. The case where a maximum of 7 beams can be formed in one cell is shown. The MAC CE consists of 8 bits. R is a reserved bit. B0 to B6 are bits representing the activation / deactivation of each beam. For example, 1 can be set as activation and 0 as deactivation. B0 to B6 are the beam indices of each beam set by RRC signaling.

[0786] The activation / deactivation information of the beams of the SCell consists of 8 bits each. The above information is connected in sequence according to the index order of the SCell. The activation / deactivation information of the beams of the deactivated SCell can be set to deactivate all beams. Alternatively, only the activation / deactivation information of the beams of the activated SCell can be connected. The connection method can be statically determined in advance by standards or the like. Both the gNB and the UE can recognize this method.

[0787] By setting the activation / deactivation information of the beam as the MAC CE in this way, the gNB can notify the UE of the activation / deactivation information of the beams formed by the SCell through MAC signaling.

[0788] Figure 16 and Figure 17 FIG. is an example of a CA setting process for beam units using MAC signaling. Figure 16 and Figure 17 are connected at the position of the boundary line BL541. Figure 16 and Figure 17 The processes shown include the same steps as the processes shown in Figure 13 and Figure 14 Therefore, the same step numbers are assigned to the same steps, and the common descriptions are omitted.

[0789] In step ST5401, the gNB notifies the UE of the configuration information of the SCell for CA and the information related to the beam corresponding to the SCell through beam 1 of the PCell. RRC dedicated signaling is used for this notification. In step ST5401, the beam notified corresponding to the SCell can be set as a beam that can be formed for the UE in CA. Thus, the gNB can notify the UE which beam in the SCell can be formed in CA.

[0790] In step ST5402, the gNB notifies the UE of the activation / deactivation information of the SCell. MAC control signaling is used for this notification. The activation / deactivation information is notified in the MAC CE. In step ST5403, the gNB notifies the UE of the activation / deactivation information of the beam of the activated SCell. MAC control signaling is used for this notification. The activation / deactivation information is notified in the MAC CE.

[0791] In step ST5404, the UE receives the SS of the activated SCell and performs synchronization. In step ST5405, the UE receives the BRS of each beam, and based on the information of the beam that can be formed in the SCell notified by the RRC signaling (specifically, at least one of the beam identifier and the BRS structure and the beam index) and the information of the beam to be activated notified by the MAC signaling (specifically the beam index), detects the beam to be monitored in the SCell. In step ST5406, the UE receives the physical downlink control channel (PDCCH) of the beam to be monitored.

[0792] Thus, the gNB can communicate with the UE via beam 1 of the SCell.

[0793] Next, refer to Figure 17 An example of the process when changing the beam for communication between the gNB and the UE in the SCell is disclosed. In step ST5407, the gNB determines to change the beam for communication with the UE. For example, it can be determined by the MAC functional unit of the gNB. In step ST5408, the gNB notifies the UE of the activation / deactivation information of the changed beam through beam 1 of the PCell. This information is notified by MAC signaling in the MAC CE.

[0794] The gNB can notify the UE of the activation / deactivation information of the changed beam through beam 1 of the SCell. The gNB can determine which communication quality is better and use the beam with better communication quality for notification.

[0795] In the case of notification via the beam of the PCell, it is not affected by the sharp deterioration of the communication quality of the beam of the SCell, and the gNB can notify the UE of the setting information of the SCell for CA and the information related to the changed beam. The UE can change it to the beam notified by the gNB.

[0796] In step ST5409, the UE receives the BRS of each beam, and based on the information of the beams that the Scell can form notified by RRC signaling (specifically, at least one of the beam identifier and the BRS structure and the beam index) and the information of the beam to be activated after the change notified by MAC signaling (specifically the beam index), the beam to be monitored within the SCell is detected. In step ST5410, the UE receives the physical downlink control channel (PDCCH) of the beam to be monitored.

[0797] Thus, the beam of the SCell communicating with the UE can be changed from beam 1 to beam 2.

[0798] By adopting the method disclosed in this Modification 1, the activation / deactivation of the beam can be performed via MAC signaling.

[0799] Therefore, the delay from the start of beam measurement by the UE to the start of using the beam with better communication quality for CA can be reduced. Therefore, the problem of being unable to start communication using the SCell due to the sharp deterioration of communication quality caused by blockage and the movement of the UE can be reduced.

[0800] In addition, the delay from the start of beam measurement by the UE to the change to the beam with better communication quality can be reduced. Therefore, the problem of communication interruption using the SCell due to the sharp deterioration of communication quality caused by blockage and the movement of the UE can be reduced.

[0801] Thus, the setting and change of the beam do not require time, and the delay until communication using the desired beam can be reduced. Therefore, the processing time for beam setting and change can be shortened, and the occurrence of being unable to start communication using the SCell and communication interruption caused by blockage and the movement of the UE can be reduced.

[0802] Modification 2 of Embodiment 6.

[0803] Disclose other methods to solve the problems described in Modification 1.

[0804] The gNB notifies the UE of the beams that the SCell can form via RRC signaling. In Embodiment 6, the UE is notified of the beams to be monitored via RRC signaling. In this Second Variant Example, the beams that the SCell can form are notified. In other words, the gNB notifies the UE of the beams that can be formed as CA in the SCell that can be set as CA. This notification can be performed for each UE. The information related to the beams for communication can be applied to the information related to the beams in Embodiment 6.

[0805] The gNB notifies the UE of the activation / deactivation information of the SCell via the L1 / L2 control signal. It is also possible to notify the activation / deactivation information of the SCell notified via RRC signaling. The gNB notifies the UE via the L1 / L2 control signal, enabling the activation / deactivation of the SCell to be notified with low latency.

[0806] As another method for the gNB to notify the UE of the activation / deactivation information of the SCell, a method of notifying using MAC signaling can be adopted. The method disclosed in Variant Example 1 of Embodiment 6 can be applied. In this case, since retransmission control is performed, notification can be carried out with a low reception error rate.

[0807] Thereby, the UE can identify which SCell to monitor. However, just by this, it is not clear which beam of the SCell can be used for communication.

[0808] The gNB notifies the UE of the activation / deactivation information of the beams formed by the SCell via the L1 / L2 control signal. The activation / deactivation information of the beams formed by the activated SCell can be notified using the L1 / L2 control signal. Instead of the activation / deactivation information of the beams formed by the SCell, the information of the beam to be activated can be notified. The identification of the beam is the information of the beam.

[0809] In the case of changing the beam for CA, the activation / deactivation setting of the beam can be changed. The gNB can notify the UE of the activation / deactivation information of the changed beam. The activation / deactivation information of the beams formed by the SCell can be set as the L1 / L2 control information. The activation / deactivation information of the beams formed by the SCell to be activated can be set.

[0810] At least one of the activation / deactivation information of the SCell and the activation / deactivation information of the beams formed by the SCell can be used as DCI. This information is notified to the UE by the gNB using the downlink. The activation / deactivation information of the SCell and the activation / deactivation information of the beam can be included in one DCI. The amount of information can be reduced, and the processing of CA setting can be simplified.

[0811] The activation / deactivation information of the SCell and the activation / deactivation information of the beam can be used as different DCIs. In the setting when the beam changes within the SCell rather than in the CA setting, only the DCI for beam activation / deactivation is used. The amount of information during beam change can be reduced, and the beam change process can be simplified.

[0812] A new format can be set in the DCI for the above information.

[0813] The beam index can be used as the activation / deactivation information of the SCell and the activation / deactivation information of the beam. Similar to Variant 1 of Embodiment 6, a bitmap can be adopted. The amount of information can be reduced.

[0814] A method for notifying the activation / deactivation information of the beam is disclosed.

[0815] The gNB notifies the UE of the activation / deactivation information of the beam through the L1 / L2 control signal of the SCell. The information of the beam to be activated can also be notified. The UE can receive the beam of the activated SCell. For example, a beam with higher received power or received quality is received. The UE determines the beam ID based on the BRS of the received beam and notifies the determined beam ID to the gNB. Alternatively, the UE can use the received beam to perform PRACH transmission and initiate the RA process, thereby notifying the beam ID to the gNB. The UE monitors this beam.

[0816] The gNB that has received the beam ID from the UE uses the L1 / L2 control signal of this beam to notify the UE of the beam activated for the UE. The UE monitors the activated beam. The UE receives the physical downlink control channel of the activated beam. One beam or multiple beams can be used. Thus, the UE can identify the activation / deactivation information of the beam of the SCell.

[0817] In the above method, after the gNB decides to start CA and notifies the UE of the activation of the SCell for CA, the process of determining the beam is performed between the UE and the gNB. Therefore, there will be a delay before the UE communicates with the cell where CA is actually set.

[0818] Another method for notifying the activation / deactivation information of the beam is disclosed.

[0819] The gNB notifies the UE of the activation / deactivation information of the beam of the SCell through the L1 / L2 control information of the PCell. The activation / deactivation information of the beam of the SCell to be activated can be notified. The information of the beam to be activated in the SCell can also be notified. The UE monitors the beam of the SCell notified by the PCell. The UE receives the physical downlink control channel of the activated beam. One beam or multiple beams can be used. Thus, the UE can identify the activation / deactivation information of the beam of the SCell.

[0820] For example, the information of the SCell to be activated and the information of the beam to be activated within the SCell can be included in the same DCI in an associated manner. The gNB notifies the above information to the UE simultaneously, so that the UE can receive the BRS in synchronization with the SCell, thereby determining the beam to be monitored and receiving the physical downlink control channel of the beam. The UE can monitor the beam of the SCell in a short time.

[0821] The physical downlink control channel of the PCell can be mapped to the DCI containing the beam information of the SCell. The DCI containing the information of the PCell can be different from the DCI containing the information of the SCell, and the DCI containing the information of the SCell can contain the information of the beam.

[0822] The above two methods of notifying the activation / deactivation information of the beam can be combined. Examples of the combination are disclosed.

[0823] The gNB notifies the UE of the information of one beam to be activated in the SCell through the L1 / L2 control information of the PCell. The information of the SCell to be activated and the information of the beam to be activated within the SCell can be included in the same DCI in an associated manner. The UE can monitor one beam of the SCell notified by the PCell. The UE receives the physical downlink control channel of the activated one beam.

[0824] The gNB notifies the UE of the information of the beam to be activated through the L1 / L2 control signal of the one beam of the SCell. Alternatively, the activation / deactivation information of the beam of the SCell can be notified. One beam or multiple beams can be used. The UE monitors the activated beam. The UE receives the phy...

Claims

1. A communication system, characterized in that, Comprising: A user device; And A base station for performing wireless communication with the user device to form Carrier Aggregation (CA), where the Carrier Aggregation is based on at least one serving cell and a secondary cell (SCell) included in the at least one serving cell. The base station uses Radio Resource Control (RRC) signaling to send information related to at least one beam used by the secondary cell to the user device. The user device receives a reference signal from the base station. And uses the information to determine a beam within the secondary cell based on the reference signal.

2. The communication system according to claim 1, characterized in that: The user device performs measurements on each beam of the at least one serving cell and sends the measurement results to the base station.

3. The communication system according to claim 1, characterized in that: The base station sends information related to the beam formed by the secondary cell to the user device.

4. The communication system according to claim 1, characterized in that: The base station sends Medium Access Control (MAC) control information to the user device, and the MAC control information includes an indication related to activation / deactivation of the at least one beam used by the at least one serving cell.

5. A base station, which is the base station in a communication system comprising a user device and the base station for performing wireless communication with the user device to form Carrier Aggregation (CA), where the Carrier Aggregation is based on at least one serving cell and a secondary cell (SCell) included in the at least one serving cell, characterized in that: The base station uses Radio Resource Control (RRC) signaling to send information related to at least one beam used by the secondary cell to the user device. And sends a reference signal for the user device to determine a beam within the secondary cell using the information to the user device.

6. A user device, which is the user device in a communication system comprising the user device and a base station for performing wireless communication with the user device to form Carrier Aggregation (CA), where the Carrier Aggregation is based on at least one serving cell and a secondary cell (SCell) included in the at least one serving cell, characterized in that: The user equipment receives information related to at least one beam used for the secondary serving cell sent from the base station by using RRC (Radio Resource Control) signaling. The user equipment receives a reference signal from the base station. And by using the information, determines a beam within the secondary serving cell based on the reference signal.

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