Communication system, communication terminal, and base station

Abstract

A wireless communication technology with high reliability, high transmission rate, and low power consumption is provided. A communication system includes a communication terminal and a base station. The base station has a plurality of transceivers configured to wirelessly communicate with the communication terminal, and uses some or all of the plurality of transceivers to wirelessly communicate with the communication terminal. The communication terminal receives a downlink synchronization signal (SSB) from at least one first transceiver newly connected (step ST1428), and establishes downlink synchronization with the at least one first transceiver using the downlink synchronization signal (step ST1429). The communication terminal establishes uplink synchronization with the at least one first transceiver through a random access process (step ST1430, step ST1431, step ST1435, step ST1436).

Description

[0001] This invention application is a divisional application of the invention patent application with international application number PCT / JP2019 / 030445, international application date of August 2, 2019, application number 201980051617.7 that entered the Chinese national phase, and titled "Communication System, Communication Terminal and Base Station". Technical Field

[0002] This invention relates to wireless communication technology. Background Technology

[0003] Within the 3GPP (3rd Generation Partnership Project), the standardization organization for mobile communication systems, a communication method known as Long Term Evolution (LTE) in terms of the radio domain and System Architecture Evolution (SAE) in terms of the overall system architecture including the core network and radio access network (hereinafter collectively referred to as the network) has been studied (e.g., Non-Patent Documents 1-5). This communication method is also referred to as a 3.9G (3.9 Generation) system.

[0004] As an access method for LTE, the downlink direction uses OFDM (Orthogonal Frequency Division Multiplexing), and the uplink direction uses SC-FDMA (Single Carrier Frequency Division Multiple Access). Furthermore, unlike W-CDMA (Wideband Code Division Multiple Access), LTE does not include line switching; it is solely a packet communication method.

[0005] use Figure 1 To explain the decisions made in 3GPP concerning the frame structure of the LTE system as described in Non-Patent Document 1 (Chapter 5). Figure 1 This is an explanatory diagram showing the structure of the radio frame used in an LTE communication system. Figure 1In this system, a radio frame is 10ms long. A radio frame is divided into 10 equal-sized subframes. Each subframe is further divided into two equal-sized slots. The first and sixth subframes of each radio frame contain downlink synchronization signals. These synchronization signals include a primary synchronization signal (P-SS) and a secondary synchronization signal (S-SS).

[0006] Non-patent document 1 (Chapter 5) describes the decisions made by 3GPP regarding channel structure in LTE systems. It is assumed that CSG (Closed Subscriber Group) cells also use the same channel structure as non-CSG cells.

[0007] The Physical Broadcast Channel (PBCH) is a downlink transmission channel from a base station (hereinafter sometimes referred to as a base station) to a mobile terminal device (hereinafter sometimes referred to as a "communication terminal"). A BCH transport block is mapped to four subframes within a 40ms interval. There is no clear signaling at 40ms intervals.

[0008] The Physical Control Format Indicator Channel (PCFICH) is a downlink transmission channel from the base station to the communication terminal. The PCFICH informs the communication terminal from the base station about the number of OFDM (Orthogonal Frequency Division Multiplexing) symbols used for PDCCHs. The PCFICH is transmitted per subframe.

[0009] The Physical Downlink Control Channel (PDCCH) is the downlink transmission channel from the base station to the communication terminal. The PDCCH notifies the recipients of resource allocation information for the Downlink Shared Channel (DL-SCH), one of the transmission channels described later; resource allocation information for the Paging Channel (PCH), another of the transmission channels described later; and HARQ (Hybrid Automatic Repeat reQuest) information related to the DL-SCH. The PDCCH transmits uplink scheduling grants. It also transmits response signals for uplink transmissions, namely Ack (Acknowledgement) and Nack (Negative Acknowledgement). The PDCCH is also known as the L1 / L2 control signal.

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

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

[0012] The Physical Uplink Control Channel (PUCCH) is the uplink transmission channel from the communication terminal to the base station. The PUCCH transmits response signals (Ack / Nack) for downlink transmissions. The PUCCH also transmits Channel State Information (CSI). CSI is composed of Rank Indicator (RI), Precoding Matrix Indicator (PMI), and Channel Quality Indicator (CQI) reports. RI refers to the rank information of the channel matrix in MIMO. PMI refers to the information of the precoding matrix used in MIMO. CQI refers to quality information indicating the quality of received data or the quality of the communication line. The PUCCH also transmits Scheduling Requests (SRs).

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

[0014] The Physical Hybrid ARQ Indicator Channel (PHICH) is the downlink transmission channel from the base station to the communication terminal. PHICH transmits the Ack / Nack response signals sent in response to the uplink transmission. The Physical Random Access Channel (PRACH) is the uplink transmission channel from the communication terminal to the base station. PRACH transmits the random access preamble.

[0015] Downlink reference signals (RS) are symbols known in LTE communication systems. Five types of downlink reference signals are defined: Cell-specific Reference Signal (CRS), MBSFN Reference Signal, UE-specific Reference Signal (DM-RS, also known as Demodulation Reference Signal), Positioning Reference Signal (PRS), and Channel State Information Reference Signal (CSI-RS). As a physical layer measurement for communication terminals, the received power (RSRP) of the reference signal is also measured.

[0016] Uplink reference signals are also known symbols in LTE communication systems. Two types of uplink reference signals are defined: Demodulation Reference Signal (DM-RS) and Sounding Reference Signal (SRS).

[0017] The transport channel described in Non-Patent Document 1 (Chapter 5) will be explained. The broadcast channel (BCH) in the downlink transport channel is broadcast to the entire coverage area of ​​its base station (cell). The BCH is mapped to the physical broadcast channel (PBCH).

[0018] The Downlink Shared Channel (DL-SCH) employs HARQ (Hybrid ARQ)-based retransmission control. DL-SCH can broadcast over the entire coverage area of ​​a base station (cell). DL-SCH supports dynamic or semi-static resource allocation. Semi-static resource allocation is also known as persistent scheduling. DL-SCH supports discontinuous reception (DRX) of communication terminals to reduce power consumption. DL-SCH is mapped to the Physical Downlink Shared Channel (PDSCH).

[0019] The Paging Channel (PCH) supports DRX (Demand Reduction) of communication terminals to reduce power consumption. The PCH is required to broadcast over the entire coverage area of ​​the base station (cell). The PCH is mapped to physical resources such as the Physical Downlink Shared Channel (PDSCH) that can be dynamically utilized for traffic.

[0020] The Multicast Channel (MCH) is used to broadcast to the entire coverage area of ​​a base station (cell). The MCH supports SFN synthesis of MBMS (Multimedia Broadcast Multicast Service) services (MTCH and MCCH) in multi-cell transmission. The MCH supports quasi-static resource allocation. The MCH is mapped to the PMCH.

[0021] HARQ (Hybrid ARQ) based retransmission control is applied to the Uplink Shared Channel (UL-SCH) in the uplink transport channel. UL-SCH supports dynamic or semi-static resource allocation. UL-SCH is mapped to the Physical Uplink Shared Channel (PUSCH).

[0022] The Random Access Channel (RACH) is restricted to control information. RACH is subject to collision risks. RACH is mapped to the Physical Random Access Channel (PRACH).

[0023] HARQ is a technique 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 transmission lines where communication quality changes, retransmission can effectively enable error correction. In particular, by combining the received results of the initial transmission with the received results of the retransmission during retransmission, the quality can be further improved.

[0024] Here's an example illustrating the retransmission method. When the receiving side cannot correctly decode the received data—in other words, when a CRC (Cyclic Redundancy Check) error occurs (CRC = NG)—a "Nack" is sent from the receiving side to the sending side. The sending side, upon receiving 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)—a "ck" is sent from the receiving side to the sending side. The sending side, upon receiving the "Ack," transmits the next data.

[0025] The logical channel described in Non-Patent Document 1 (Chapter 6) will be explained. The Broadcast Control Channel (BCCH) is a downlink channel used to broadcast system control information. The BCCH, as a logical channel, is mapped to either the Broadcast Channel (BCH) as a transmission channel or the Downlink Shared Channel (DL-SCH).

[0026] The Paging Control Channel (PCCH) is a downlink channel used to transmit paging information and system information updates. The PCCH is used when the network is unaware of the cell location of the communicating terminal. As a logical channel, the PCCH is mapped to the Paging Channel (PCH), which is used as a transport channel.

[0027] The Common Control Channel (CCCH) is a channel used for transmitting control information between a communication terminal and a base station. The CCCH is used when there is no RRC connection between the communication terminal and the network. In the downlink direction, the CCCH is mapped to the Downlink Shared Channel (DL-SCH) used as a transport channel. In the uplink direction, the CCCH is mapped to the Uplink Shared Channel (UL-SCH) used as a transport channel.

[0028] The Multicast Control Channel (MCCH) is a downlink channel used for point-to-multipoint transmission. The MCCH is used to send one or more MBMS control messages (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 serves as the transport channel.

[0029] The Dedicated Control Channel (DCCH) is a channel used to transmit dedicated control information between a communication terminal and the network in a point-to-point manner. The DCCH is used when the communication terminal is in 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).

[0030] A Dedicated Traffic Channel (DTCH) is a point-to-point communication channel used to send user information to dedicated communication terminals. DTCH exists in both the uplink and downlink. In the uplink, DTCH is mapped to the Uplink Shared Channel (UL-SCH), and in the downlink, it is mapped to the Downlink Shared Channel (DL-SCH).

[0031] The Multicast Traffic Channel (MTCH) is a downlink channel used to send voice data from the network to the communication terminal. The MTCH is used only by the communication terminal during MBMS reception. The MTCH is mapped to the Multicast Channel (MCH).

[0032] CGI stands for Cell Global Identifier. ECGI stands for E-UTRAN Cell Global Identifier. In LTE, LTE-A (Long Term Evolution Advanced) and UMTS (Universal Mobile Telecommunication System), CSG (Closed Subscriber Group) cells were introduced.

[0033] Location tracking of a communication terminal is performed on a unit consisting of one or more cells. Location tracking is used to locate the communication terminal even in standby mode, enabling calls to the terminal; in other words, it is performed to enable calls to the communication terminal. The area used for location tracking of this communication terminal is called the tracking area.

[0034] Furthermore, within 3GPP, the Long Term Evolution Advanced (LTE-A) standard, version 10, is continuously being developed (see Non-Patent Documents 3 and 4). LTE-A is based on the LTE radio inter-communication method, and is constructed by adding some new technologies to it.

[0035] In LTE-A systems, to support wider transmission bandwidths of up to 100MHz, carrier aggregation (CA), which combines two or more component carriers (CCs), has been studied. CA is described in Non-Patent Literature 1.

[0036] In the case of a CA (Cybernetic Association), the UE has a unique RRC connection with the network (NW). Within the RRC connection, a serving cell provides NAS (Navigation Information and Security) input. This cell is called the Primary Cell (PCell). In the downlink, the carrier corresponding to the PCell is the Downlink Primary Component Carrier (DL PCC). In the uplink, the carrier corresponding to the PCell is the Uplink Primary Component Carrier (UL PCC).

[0037] Based on the UE's capabilities, secondary serving cells (SCells) are constructed to form a group of serving cells together with PCells. In the downlink, the carrier corresponding to the SCell is the Downlink Secondary Component Carrier (DL SCC). In the uplink, the carrier corresponding to the SCell is the Uplink Secondary Component Carrier (UL SCC).

[0038] For a UE, a group of serving cells is formed by one PCell and one or more SCells.

[0039] Furthermore, as a new technology for LTE-A, there are technologies that support wider bandwidth (Wider bandwidth extension) and Coordinated Multiple Point Transmission and Reception (CoMP) technology. CoMP, which was researched for the implementation of LTE-A in 3GPP, is described in Non-Patent Literature 1.

[0040] Furthermore, 3GPP is researching the use of small eNBs (hereinafter sometimes referred to as "small-scale base station devices") to cope with the expected high traffic volume. For example, technologies are being researched to improve frequency utilization efficiency and increase communication capacity by setting up multiple small eNBs and forming multiple small cells. Specifically, there is dual connectivity (DC), where the UE communicates by connecting to two eNBs. DC is described in Non-Patent Document 1.

[0041] Sometimes one of the eNBs performing dual connections (DC) is called the "primary eNB (MeNB)" and the other is called the "secondary eNB (SeNB)".

[0042] Mobile network traffic is trending upwards, and communication speeds are continuously increasing. With the official implementation of LTE and LTE-A, further acceleration in communication speeds is foreseeable.

[0043] Furthermore, fifth-generation (hereinafter sometimes referred to as "5G") radio access systems are under investigation, with the goal of enabling next-generation mobile communications to begin service after 2020. For example, in Europe, the organization METIS is summarizing the requirements for 5G (see Non-Patent Document 5).

[0044] In 5G wireless access systems, for LTE systems, assuming the system capacity is 1000 times greater, the data transmission speed is 100 times greater, the data processing latency is 1 / 10th, and the number of simultaneous connections of communication terminals is 100 times greater, we can list the necessary conditions for achieving further low power consumption and low device cost.

[0045] To meet these requirements, discussions on the 5G standard are ongoing in 3GPP as version 15 (see non-patent documents 6-18). The technology for the 5G radio interface is called "New Radio Access Technology" ("New Radio" is abbreviated as "NR").

[0046] The discussion on NR systems based on LTE and LTE-A systems continues to advance, but changes and additions from LTE and LTE-A systems will be made in the following aspect.

[0047] As an access method for NR, OFDM is used in the downlink direction, and OFDM and DFT-s-OFDM (DFT-spread-OFDM) are used in the uplink direction.

[0048] In NR, higher frequencies can be used compared to LTE to increase transmission speed and reduce processing latency.

[0049] In NR, cell coverage is ensured by changing the direction of the beam (beam scanning) while forming a narrow beam-shaped transmit and receive range (beamforming).

[0050] The NR frame structure supports a wide variety of subcarrier spacings, i.e., a wide variety of parameter sets (Numerology). In NR, one subframe is 1 millisecond, and one time slot consists of 14 symbols, regardless of the parameter set. In addition, the number of time slots contained in one subframe is one in the parameter set with a subcarrier spacing of 15 kHz, and increases proportionally with the subcarrier spacing in other parameter sets (see Non-Patent Document 13 (TS38.211 v15.0.0)).

[0051] In NR, the downlink synchronization signal is transmitted from the base station as a Synchronization Signal Burst (SS Burst), which is sent at a specified period for a specified duration. An SS Burst consists of a Synchronization Signal Block (SS Block) for each beam of the base station. The base station changes beams to transmit the SS Blocks for each beam during the duration of the SS Burst. An SS Block consists of P-SS, S-SS, and PBCH.

[0052] In NR, a Phase Tracking Reference Signal (PTRS) is added as the downlink reference signal to reduce the impact of phase noise. The uplink reference signal also incorporates a PTRS in the same way as the downlink reference signal.

[0053] In NR, in order to flexibly switch between DL and UL within a time slot, a time slot format indication (SFI) is added to the information contained in the PDCCH.

[0054] In addition, in NR, the base station pre-defines a portion of the carrier frequency band for the UE (hereinafter sometimes called the Bandwidth Part (BWP)). The UE transmits and receives data between itself and the base station in this BWP, thereby trying to reduce the power consumption in the UE.

[0055] In 3GPP, DC methods are discussed, including DC performed by LTE base stations and NR base stations connected to EPC, DC performed by NR base stations connected to 5G core systems, and DC performed by LTE base stations and NR base stations connected to 5G core systems (see Non-Patent Literature 12, 16, 19).

[0056] In addition, several new technologies were explored in 3GPP. For example, improvements in communication reliability supported by multiple TRPs (Transmission Reception Points) in a base station were explored (see Non-Patent Document 20), rapid recovery from MCG (Master Cell Group) failures in a DC (see Non-Patent Document 21), and methods for setting up multiple carriers in sidelinks were explored (see Non-Patent Document 22), etc.

[0057] Existing technical documents

[0058] Non-patent literature

[0059] Non-patent document 1: 3GPP TS 36.300 V15.2.0

[0060] Non-patent document 2: 3GPP S1-083461

[0061] Non-patent document 3: 3GPP TR 36.814 V9.2.0

[0062] Non-patent document 4: 3GPP TR 36.912 V15.0.0

[0063] Non-patent literature 5: "Scenarios, requirements and KPIs for 5G mobile and wireless system", ICT-317669-METIS / D1.1

[0064] Non-patent document 6: 3GPP TR 23.799 V14.0.0

[0065] Non-patent document 7: 3GPP TR 38.801 V14.0.0

[0066] Non-patent document 8: 3GPP TR 38.802 V14.2.0

[0067] Non-patent document 9: 3GPP TR 38.804 V14.0.0

[0068] Non-patent document 10: 3GPP TR 38.912 V14.1.0

[0069] Non-patent document 11: 3GPP RP-172115

[0070] Non-patent document 12: 3GPP TS 37.340 V15.2.0

[0071] Non-patent document 13: 3GPP TS 38.211 V15.2.0

[0072] Non-patent document 14: 3GPP TS 38.213 V15.2.0

[0073] Non-patent document 15: 3GPP TS 38.214 V15.2.0

[0074] Non-patent document 16: 3GPP TS 38.300 V15.2.0

[0075] Non-patent document 17: 3GPP TS 38.321 V15.2.0

[0076] Non-patent document 18: 3GPP TS 38.212 V15.2.0

[0077] Non-patent document 19: 3GPP RP-161266

[0078] Non-patent document 20: 3GPP RP-181453

[0079] Non-patent document 21: 3GPP R2-1807081

[0080] Non-patent document 22: 3GPP TS 36.331 V15.2.2

[0081] Non-patent document 23: 3GPP R2-1802473

[0082] Non-patent document 24: 3GPP TR 36.885 V14.0.0

[0083] Non-patent document 25: 3GPP R2-1708062

[0084] Non-patent document 26: 3GPP TS 38.331 V15.2.1

[0085] Non-patent document 27: 3GPP R1-1714239 Summary of the Invention

[0086] The technical problem that the invention aims to solve

[0087] When a base station uses multiple TRPs to communicate with the UE, the backhaul delay from the base station to each TRP and the transmission delay from each TRP to the UE differ for each TRP. However, how the UE achieves synchronization with each TRP is not disclosed. Therefore, the UE cannot perform handover between base station-affiliated TRPs and / or the UE cannot communicate with multiple TRPs simultaneously. As a result, reliability and throughput are reduced.

[0088] Furthermore, in side links (SL) supporting D2D (Device to Device) and V2V (Vehicle to Vehicle) communication, multi-carrier operation is supported. However, if the timing settings of the Physical Sidelink Control Channel (PSCCH) and Physical Sidelink Shared Channel (PSSCH) differ for each carrier, the receiving UE under SL needs to receive the PSCCH and PSSCH at the timings set for each carrier. Therefore, power consumption increases.

[0089] In view of the above-mentioned technical problems, one of the objectives of the present invention is to provide a highly reliable, high-transmission-rate, and low-power wireless communication technology in at least one of NR and direct-link communication.

[0090] Technical solutions adopted to solve technical problems

[0091] According to the present invention, a communication system is provided, comprising: a communication terminal; and a base station having a plurality of transceivers configured to wirelessly communicate with the communication terminal, the base station being configured to use some or all of the plurality of transceivers to wirelessly communicate with the communication terminal, the communication terminal receiving a downlink synchronization signal from at least one newly connected first transceiver, establishing downlink synchronization with at least one first transceiver using the downlink synchronization signal, and establishing uplink synchronization with at least one first transceiver through random access processing.

[0092] In addition, according to the present invention, a communication terminal is provided, configured to perform wireless communication with some or all of the multiple transceivers via a base station having multiple transceivers, wherein the communication terminal receives a downlink synchronization signal from at least one newly connected first transceiver, establishes downlink synchronization with at least one first transceiver using the downlink synchronization signal, and establishes uplink synchronization with at least one first transceiver through random access processing.

[0093] Furthermore, according to the present invention, a base station is provided, which is configured to wirelessly connect with a communication terminal. The base station has multiple transceivers and is configured to use some or all of the multiple transceivers to wirelessly communicate with the communication terminal. When the communication terminal initiates random access processing, the base station performs the random access processing with the communication terminal via at least one first transceiver newly connected to the communication terminal.

[0094] Invention Effects

[0095] According to the present invention, high reliability, high transmission rate and low power consumption can be achieved.

[0096] The objects, features, aspects, and advantages of the present invention will become more apparent from the following detailed description and accompanying drawings. Attached Figure Description

[0097] Figure 1 This is an explanatory diagram showing the structure of the radio frame used in an LTE communication system.

[0098] Figure 2 This is a block diagram showing the overall structure of a communication system 200 using the LTE method discussed in 3GPP.

[0099] Figure 3 This is a block diagram representing the overall structure of the NR-based communication system 210 discussed in 3GPP.

[0100] Figure 4 This is a structural diagram of the DC structure of the eNB and gNB connected to the EPC.

[0101] Figure 5 This is a structural diagram of the DC structure of the gNB connected to the NG core.

[0102] Figure 6 This is a structural diagram of the DC structure of the eNB and gNB connected to the NG core.

[0103] Figure 7 This is a structural diagram of the DC structure of the eNB and gNB connected to the NG core.

[0104] Figure 8 It is shown Figure 2 The diagram shows the structure of the mobile terminal 202.

[0105] Figure 9 It is shown Figure 2 The diagram shows the structure of base station 203.

[0106] Figure 10 This is a block diagram showing the structure of the MME.

[0107] Figure 11 This is a block diagram showing the structure of 5GC.

[0108] Figure 12 This is a flowchart illustrating the process from cell search to standby mode performed by a communication terminal (UE) in an LTE communication system.

[0109] Figure 13 This is a diagram illustrating an example of the cell structure of an NR system.

[0110] Figure 14 This is a diagram showing the operation of switching the connection TRP of the UE in implementation 1.

[0111] Figure 15 This is a diagram showing the operation of switching the connection TRP of the UE in implementation 1.

[0112] Figure 16 This is a diagram showing the operation of a UE connected to multiple TRPs switching connection TRPs, relating to implementation 1.

[0113] Figure 17 This is a diagram showing the operation of a UE connected to multiple TRPs switching connection TRPs, relating to implementation 1.

[0114] Figure 18 This is a diagram showing the operation of adding a connection TRP in the UE, relating to implementation 1.

[0115] Figure 19 This is a diagram showing the operation of adding a connection TRP in the UE, relating to implementation 1.

[0116] Figure 20 This is a diagram showing the actions of summarizing and adding multiple TRPs connected to the UE, relating to implementation 1.

[0117] Figure 21 This is a diagram showing the actions of summarizing and adding multiple TRPs connected to the UE, relating to implementation 1.

[0118] Figure 22 This is a diagram showing the release operation of the connection TRP in the UE, relating to implementation 1.

[0119] Figure 23 This is a variation of implementation 1, showing a diagram of the handover operation of the downlink communication TRP in the UE.

[0120] Figure 24 This is a variation of implementation 1, showing a diagram of the handover operation of the downlink communication TRP in the UE.

[0121] Figure 25 This is a variation of implementation 1, illustrating another example of the operation of switching of the TRP for downlink communication in the UE.

[0122] Figure 26 This is a variation of implementation 1, illustrating another example of the operation of switching of the TRP for downlink communication in the UE.

[0123] Figure 27 This is a variation of implementation 1, illustrating another example of the operation of switching of the TRP for downlink communication in the UE.

[0124] Figure 28 This is a variation of implementation 1, illustrating another example of the operation of switching of the TRP for downlink communication in the UE.

[0125] Figure 29 This is a variation 2 of implementation 1, showing a diagram of the handover operation of the uplink communication TRP in the UE.

[0126] Figure 30 This is a variation 2 of implementation 1, showing a diagram of the handover operation of the uplink communication TRP in the UE.

[0127] Figure 31 This is a variation 2 of implementation 1, showing another example of the operation of switching of the TRP for uplink communication in the UE.

[0128] Figure 32This is a variation 2 of implementation 1, showing another example of the operation of switching of the TRP for uplink communication in the UE.

[0129] Figure 33 This is a variation 2 of implementation 1, showing another example of the operation of switching of the TRP for uplink communication in the UE.

[0130] Figure 34 This is a variation 2 of implementation 1, showing another example of the operation of switching of the TRP for uplink communication in the UE.

[0131] Figure 35 This is a diagram showing the action of switching the recovery application task from an MCG failure, related to implementation 4.

[0132] Figure 36 This is a variation of implementation 4, showing a diagram of the action of switching the recovery application task from an MCG failure.

[0133] Figure 37 This is a diagram showing the use of multiple carriers in SL, relating to implementation method 5.

[0134] Figure 38 This is an example of implementation 5, which provides a sequence of PSCCH and PSSCH with the same timing set on multiple carriers.

[0135] Figure 39 This is an example of implementation 5, which provides a sequence of PSCCH and PSSCH with the same timing set on multiple carriers.

[0136] Figure 40 This is a variation of implementation 5, an example of a sequence of PSCCH and PSSCH with the same timing set on multiple carriers.

[0137] Figure 41 This is a conceptual diagram illustrating PC5-based V2V for implementation method 6.

[0138] Figure 42 This is a conceptual diagram illustrating Uu-based V2V for implementation method 6.

[0139] Figure 43 This relates to implementation method 6, which illustrates group replication using PC5-based V2V and Uu-based V2V.

[0140] Figure 44 This is a diagram showing grouped replication in UE_tx, related to implementation 6.

[0141] Figure 45This is a diagram showing an example of packet replication using PC5-based V2V communication and Uu-based V2V communication in implementation 6.

[0142] Figure 46 This is a diagram showing an example of a sequence of bearer settings for grouped replication, relating to implementation 6.

[0143] Figure 47 This is a diagram showing an example of a sequence of bearer settings for grouped replication, relating to implementation 6.

[0144] Figure 48 This is a variation of implementation 6, showing a diagram of an example of packet replication using PC5-based V2V communication and Uu-based V2V communication.

[0145] Figure 49 This is an example diagram of a sequence of bearer settings for grouped replication, relating to Embodiment 6, of Embodiment 1.

[0146] Figure 50 This is an example diagram of a sequence of bearer settings for grouped replication, relating to Embodiment 6, of Embodiment 1.

[0147] Figure 51 This is a variation of implementation 6, showing a diagram of an example of packet replication using PC5-based V2V communication and Uu-based V2V communication.

[0148] Figure 52 This is a variation 2 of implementation 6, showing an example of a sequence for setting a fork bearing.

[0149] Figure 53 This is a variation 2 of implementation 6, showing an example of a sequence for setting a fork bearing. Detailed Implementation

[0150] Implementation method 1.

[0151] Figure 2 This is a block diagram showing the overall structure of a communication system 200 using the LTE method discussed in 3GPP. Figure 2The following explanation is provided. The radio access network is referred to as E-UTRAN (Evolved Universal Terrestrial Radio Access Network) 201. The communication terminal device, namely the mobile terminal device (hereinafter referred to as "Mobile Terminal (User Equipment): UE)") 202, can wirelessly communicate 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.

[0152] Here, "communication terminal device" refers not only to mobile terminal devices such as mobile phone terminals, but also to stationary devices such as sensors. In the following description, "communication terminal device" may sometimes be abbreviated as "communication terminal".

[0153] If the control protocols for the mobile terminal 202, such as RRC (Radio Resource Control), and user-level protocols (hereinafter sometimes referred to as U-Plane), 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 consists of one or more base stations 203.

[0154] The Radio Resource Control (RRC) protocol between mobile terminal 202 and base station 203 performs broadcasting, paging, and RRC connection management. The states of base station 203 and mobile terminal 202 in the RRC are RRC_IDLE and RRC_CONNECTED.

[0155] During RRC_IDLE, PLMN (Public Land Mobile Network) selection, System Information (SI) broadcasting, paging, cell re-selection, and mobility settings are performed. During RRC_CONNECTED, the mobile terminal has an RRC connection and can send and receive data with the network. Furthermore, during RRC_CONNECTED, handover (HO) and neighbor cell determination (measurement) are performed.

[0156] Base station 203 consists of one or more eNBs 207. Additionally, the system consisting of the EPC (Evolved Packet Core) as the core network and the E-UTRAN 201 as the radio access network is called EPS (Evolved Packet System). Sometimes, the EPC as the core network and the E-UTRAN 201 as the radio access network are collectively referred to as the "network".

[0157] The eNB 207 connects to the Mobility Management Entity (MME), Serving Gateway (S-GW), or an MME / S-GW unit (hereinafter sometimes referred to as "MME unit") 204, which includes both the MME and S-GW, via the S1 interface, and communicates control information between the eNB 207 and the MME unit 204. One eNB 207 can connect to multiple MME units 204. The eNBs 207s also connect to each other via the X2 interface, communicating control information between them.

[0158] MME 204 is a host device, specifically a host node, that controls the connection between eNB 207 (as a base station) and mobile terminal (UE) 202. MME 204 constitutes the EPC (Electronic Process Control) as the core network. Base station 203 constitutes E-UTRAN 201.

[0159] Base station 203 can constitute one cell or multiple cells. Each cell has a predetermined range as its coverage area, which enables communication with mobile terminal 202, and wireless communication is conducted with mobile terminal 202 within the coverage area. When a base station 203 constitutes multiple cells, each cell is configured to communicate with mobile terminal 202.

[0160] Figure 3This is a block diagram showing the overall structure of a 5G communication system 210 as discussed in 3GPP. Figure 3 The following explanation is provided. The radio access network is referred to as NG-RAN (Next Generation Radio Access Network) 211. UE 202 can wirelessly communicate with NR base station equipment (hereinafter referred to as "NR base station (NG-RAN NodeB: gNB)") 213, transmitting and receiving signals wirelessly. Additionally, the core network is referred to as 5G Core (5GC).

[0161] If the control protocols for UE202, such as RRC (Radio Resource Control), and user-level protocols (hereinafter sometimes referred to as U-Plane), such as SDAP (Service Data Adaptation Protocol), PDCP (Packet Data Convergence Protocol), RLC (Radio Link Control), MAC (Medium Access Control), and PHY (Physical layer), terminate at NR base station 213, then NG-RAN consists of one or more NR base stations 213.

[0162] The Radio Resource Control (RRC) protocol between UE202 and NR base station 213 functions the same as in LTE. The states between NR base station 213 and UE202 in RRC include RRC_IDLE, RRC_CONNECTED, and RRC_INACTIVE.

[0163] RRC_IDLE and RRC_CONNECTED are the same as in LTE. In RRC_INACTIVE, while maintaining the connection between the 5G core and NR base station 213, system information (SI) broadcasting, paging, cell re-selection, and mobility are performed.

[0164] The gNB217 connects to the Access and Mobility Management Function (AMF), Session Management Function (SMF), or User Plane Function (UPF), or an AMF / SMF / UPF unit (hereinafter sometimes referred to as "5GC unit") 214 via the NG interface. Control information and / or user data communication occurs between the gNB217 and the 5GC unit 214. The NG interface is a collective term for the N2 interface between the gNB217 and the AMF, the N3 interface between the gNB217 and the UPF, the N11 interface between the AMF and the SMF, and the N4 interface between the UPF and the SMF. One gNB217 can connect to multiple 5GC units 214. The gNB217s are connected to each other via the Xn interface, facilitating communication of control information and / or user data between them.

[0165] NR base station 213 is similar to base station 203 and can form one or more cells. When one NR base station 213 forms multiple cells, each cell is configured to communicate with UE 212.

[0166] The gNB217 can be divided into a Central Unit (hereinafter sometimes referred to as CU) 218 ​​and a Distributed Unit (hereinafter sometimes referred to as DU) 219. A CU 218 is configured as one unit within the gNB217. One or more DUs 219 are configured within the gNB217. The CU 218 is connected to the DU 219 via an F1 interface, facilitating communication of control information and / or user data between the CU 218 and DU 219.

[0167] Figure 4 This is a diagram showing the DC structure of the eNB and gNB connected to the EPC. Figure 4 In the diagram, solid lines represent U-Plane connections, and dashed lines represent C-Plane connections. Figure 4 In this configuration, eNB223-1 is the primary base station, and gNB224-2 is the secondary base station (this DC structure is sometimes referred to as EN-DC). Figure 4 The example shown is an example of a U-Plane connection between MME 204 and gNB 224-2 via eNB 223-1, but it can also be made directly between MME 204 and gNB 224-2.

[0168] Figure 5 This is a diagram showing the structure of the DC (Distributed DC) operation performed by the gNB connected to the NG core. Figure 5In the diagram, solid lines represent U-Plane connections, and dashed lines represent C-Plane connections. Figure 5 In this configuration, gNB224-1 is the primary base station, and gNB224-2 is the secondary base station (this DC structure is sometimes referred to as NR-DC). Figure 5 The example shown is an example of a U-Plane connection between 5GC section 214 and gNB224-2 being made via gNB224-1, but it can also be made directly between 5GC section 214 and gNB224-2.

[0169] Figure 6 This diagram illustrates the structure of the DC (Distributed DC) operation performed by the eNB and gNB connected to the NG core. Figure 6 In the diagram, solid lines represent U-Plane connections, and dashed lines represent C-Plane connections. Figure 6 In this configuration, eNB226-1 is the primary base station, and gNB224-2 is the secondary base station (this DC structure is sometimes referred to as NG-EN-DC). Figure 6 The example shown is an example of a U-Plane connection between 5GC section 214 and gNB224-2 via eNB226-1, but it can also be made directly between 5GC section 214 and gNB224-2.

[0170] Figure 7 This diagram illustrates other structures of the DC (Distributed DC) implemented by the eNB and gNB connected to the NG core. Figure 7 In the diagram, solid lines represent U-Plane connections, and dashed lines represent C-Plane connections. Figure 7 In this configuration, gNB224-1 is the primary base station, and eNB226-2 is the secondary base station (this DC structure is sometimes referred to as NE-DC). Figure 7 The example shown is an example of a U-Plane connection between the 5GC section 214 and the eNB 226-2 being made via the gNB 224-1, but it can also be made directly between the 5GC section 214 and the eNB 226-2.

[0171] Figure 8 It shows Figure 2 The diagram shows the structure of the mobile terminal 202. Figure 8The transmission process of the mobile terminal 202 shown will be described. First, control data from the protocol processing unit 301 and 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 for error correction and other encoding processing. Alternatively, data may be output directly from the transmission data buffer unit 303 to the modulation unit 305 without encoding processing. The data encoded by the encoding unit 304 is then modulated in the modulation unit 305. Precoding for MIMO may also be performed 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 wireless transmission frequency. Afterward, the transmission signal is transmitted from antennas 307-1 to 307-4 to the base station 203. Figure 8 The example shown has four antennas, but the number of antennas is not limited to four.

[0172] Furthermore, the receiving process of the mobile terminal 202 is performed as follows. Wireless signals from the base station 203 are received via antennas 307-1 to 307-4. The received signal is converted from a wireless receiving frequency to a baseband signal in the frequency conversion unit 306, and demodulation processing is performed in the demodulation unit 308. Waiting calculations and multiplication processes can be performed in the demodulation unit 308. The demodulated data is transmitted to the decoding unit 309 for error correction and other decoding processing. Of the decoded data, control data is transmitted to the protocol processing unit 301, and 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. Therefore, although in Figure 8 The details have been omitted, but the control unit 310 is connected to each of the units 301 to 309. Figure 8 In this context, the number of antennas used for transmitting and the number of antennas used for receiving in the mobile terminal 202 may be the same or different.

[0173] Figure 9 It is shown Figure 2 The diagram shows the structure of base station 203. Figure 9 The transmission processing of the base station 203 shown will be described. The EPC communication unit 401 performs data transmission and reception between base station 203 and EPC (MME unit 204, etc.), HeNBGW 205, etc. The 5GC communication unit 412 performs data transmission and reception between base station 203 and 5GC (5GC unit 214, etc.). Other base station communication units 402 perform data transmission and reception with other base stations. The EPC communication unit 401, 5GC communication unit 412, and other base station communication units 402 exchange information with the protocol processing unit 403. Control data from the protocol processing unit 403, as well as user data and control data from the EPC communication unit 401, 5GC communication unit 412, and other base station communication units 402, are stored in the transmission data buffer unit 404.

[0174] The data stored in the transmission data buffer 404 is transmitted to the encoding unit 405 for error correction and other encoding processing. Alternatively, data may be output directly from the transmission data buffer 404 to the modulation unit 406 without encoding processing. The encoded data is modulated in the modulation unit 406. MIMO precoding may also be performed in the modulation unit 406. The modulated data is converted into a baseband signal and then output to the frequency conversion unit 407, where it is converted into a wireless transmission frequency. Afterward, the transmission signal is transmitted to one or more mobile terminals 202 using antennas 408-1 to 408-4. Figure 9 The example shown has four antennas, but the number of antennas is not limited to four.

[0175] Furthermore, the reception processing of base station 203 is performed as follows. Wireless signals from one or more mobile terminals 202 are received by antenna 408. The received signal is converted from the wireless receiving frequency to a baseband signal by frequency conversion unit 407, and demodulated by demodulation unit 409. The demodulated data is transmitted to decoding unit 410 for error correction and other decoding processing. Of the decoded data, control data is transmitted to protocol processing unit 403, 5GC communication unit 412, EPC communication unit 401, or other base station communication units 402; user data is transmitted to 5GC communication unit 412, EPC communication unit 401, and other base station communication units 402. A series of processes of base station 203 are controlled by control unit 411. Thus, although in Figure 4 The details have been omitted, but the control unit 411 is connected to each of the units 401-410. Figure 9 In this context, the number of antennas used for transmitting and the number of antennas used for receiving in base station 203 can be the same or different.

[0176] Figure 9 This is a block diagram showing the structure of base station 203, but base station 213 can also be configured with the same structure. Additionally, for... Figure 8 and Figure 9 The number of antennas in the mobile terminal 202 and the number of antennas in the base station 203 can be the same or different.

[0177] Figure 10 This is a block diagram showing the structure of the MME. Figure 10 The above is shown in the middle. Figure 2The structure of MME 204a included in MME 204 is shown. PDN GW communication unit 501 performs data transmission and reception between MME 204a and PDN GW. Base station communication unit 502 performs data transmission and reception between MME 204a and base station 203 via the S1 interface. When the data received from the PDN GW is user data, the user data is transmitted from PDN GW communication unit 501 to base station communication unit 502 via user plane communication unit 503, and then sent to one or more base stations 203. When the data received from base station 203 is user data, the user data is transmitted from base station communication unit 502 to PDN GW communication unit 501 via user plane communication unit 503, and then sent to PDN GW.

[0178] 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.

[0179] The control plane control unit 505 includes a NAS security unit 505-1, an SAE bearer control unit 505-2, and an idle state mobility management unit 505-3, and performs all processing for the control plane (hereinafter sometimes referred to as C-Plane). The NAS security unit 505-1 handles the security of NAS (Non-Access Stratum) messages. The SAE bearer control unit 505-2 manages the SAE (System Architecture Evolution) bearer. The idle state mobility management unit 505-3 manages mobility in standby state (idle state; LTE-IDLE state, or simply idle), generates and controls paging signals in standby state, adds, deletes, updates, retrieves, and manages the tracking area list for one or more mobile terminals 202 within the coverage area.

[0180] MME204a distributes paging signals to one or more base stations 203. Furthermore, MME204a performs mobility control in the idle state. MME204a manages the tracking area list when the mobile terminal is in idle state and active state. MME204a initiates the paging protocol by sending a paging message to cells belonging to the tracking area registered by the UE. The management of the CSG, CSG ID, and whitelist of the Home-eNB206 connected to MME204a can be performed by the idle state mobility management unit 505-3.

[0181] Figure 11 This is a block diagram showing the structure of 5GC. Figure 11 The above is shown in the figure. Figure 3 The structure of the 5GC section 214 shown. Figure 11 It shows in Figure 5 The 5GC unit 214 shown includes structures such as AMF, SMF, and UPF. The Data Network Communication Unit 521 performs data transmission and reception between the 5GC unit 214 and the data network. The Base Station Communication Unit 522 performs data transmission and reception between the 5GC unit 214 and the base station 203 via the S1 interface, and / or between the 5GC unit 214 and the base station 213 via the NG interface. When the data received from the data network is user data, the user data is transmitted from the Data Network Communication Unit 521 to the Base Station Communication Unit 522 via the User Layer Communication Unit 523, and then sent to one or more base stations 203 and / or 213. When the data received from the base station 203 and / or 213 is user data, the user data is transmitted from the Base Station Communication Unit 522 to the Data Network Communication Unit 521 via the User Layer Communication Unit 523, and then sent to the data network.

[0182] When the data received from the data network is control data, the control data is transmitted from the data network communication unit 521 to the session management unit 527 via the user plane control unit 523. The session management unit 527 then transmits the control data to the control plane control unit 525. When the data received from base station 203 and / or base station 213 is control data, the control data is transmitted from the base station communication unit 522 to the control plane control unit 525. The control plane control unit 525 then transmits the control data to the session management unit 527.

[0183] The control plane control unit 525 includes a NAS security unit 525-1, a PDU session control unit 525-2, and an Idle State mobility management unit 525-3, and performs all processing for the control plane (hereinafter sometimes referred to as C-Plane). The NAS security unit 525-1 handles the security of NAS (Non-Access Stratum) messages. The PDU session control unit 525-2 manages the PDU session between the mobile terminal 202 and the 5GC unit 214. The Idle State Mobility Management unit 525-3 manages mobility in standby state (Idle State; RRC_IDLE state, or simply idle), generates and controls paging signals in standby state, adds, deletes, updates, retrieves, and manages the tracking area list for one or more mobile terminals 202 within the coverage area.

[0184] The 5GC unit 214 distributes paging signals to one or more base stations 203 and / or base station 213. Additionally, the 5GC unit 214 performs mobility control in the idle state. The 5GC unit 214 manages the tracking area list when the mobile terminal is in the idle state, and in the inactive and active states. The 5GC unit 214 initiates the paging protocol by sending a paging message to cells belonging to the tracking area registered by the UE.

[0185] Next, an example of a cell search method in a communication system is shown. Figure 12 This is a flowchart illustrating the process of a communication terminal (UE) in an LTE communication system from cell search to standby operation. If the communication terminal starts cell search, in step ST601, the first synchronization signal (P-SS) and the second synchronization signal (S-SS) sent from the surrounding base stations are used to obtain the synchronization of time slot timing and frame timing.

[0186] P-SS and S-SS are collectively referred to as the Synchronization Signal (SS). The Synchronization Signal (SS) contains a synchronization code that corresponds one-to-one with the PCI assigned to each cell. This study investigated setting the number of PCIs to 504. Synchronization was achieved using these 504 PCIs, and the PCIs of synchronized cells were detected (determined).

[0187] Next, in step ST602, the reference signal (RS) sent from the base station to each cell after synchronization is achieved, i.e., the cell-specific reference signal (CRS), is measured, and the received power (RSRP) of the RS is determined. The reference signal (RS) uses a code that corresponds one-to-one with the PCI. This code can be used to obtain correlation and thus separate the cell from others. By deriving the RS code of the cell based on the PCI determined in step ST601, the RS can be detected and its received power measured.

[0188] Next, in step ST603, the cell with the best RS reception quality is selected from one or more cells detected up to step ST602, for example, the cell with the highest RS reception power, i.e., the best cell.

[0189] Next, in step ST604, the PBCH of the optimal cell is received to obtain the broadcast information, i.e., the BCCH. The BCCH on the PBCH maps to the MIB (Master Information Block), which contains cell structure information. Therefore, by receiving the PBCH and obtaining the BCCH, the MIB can be obtained. Information in the MIB includes, for example, the DL (downlink) system bandwidth (also known as transmission bandwidth configuration), the number of transmit antennas, and the SFN (System Frame Number).

[0190] Next, in step ST605, the cell structure information based on the MIB is received from the DL-SCH of the cell, 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 ≥ 2 integers). In addition, SIB1 also contains the Tracking Area Code (TAC).

[0191] Next, in step ST606, the communication terminal compares the TAC of SIB1 received in step ST605 with the TAC portion of the Tracking Area Identity (TAI) in the tracking area list already stored by the communication terminal. The tracking area list is also called the TAI list. TAI is identification information used to identify the tracking area, consisting of the 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 tracking area code.

[0192] If the comparison result obtained in step S606 is the same as the TAC received in step ST605, and it is also included in the tracking area list, then the communication terminal enters standby mode in that cell. If the comparison result is the same as the TAC received in step ST605, and it is not included in the tracking area list, then the communication terminal requests a change of tracking area from the core network (EPC) containing the MME, etc., through that cell to perform a TAU (Tracking Area Update).

[0193] exist Figure 12 The example shown illustrates the actions from cell search to standby in LTE mode. However, in NR mode, in step ST603, in addition to selecting the best cell, the best beam can also be selected. Furthermore, in NR mode, in step ST604, beam information, such as the beam identifier, can be obtained. Additionally, in NR mode, in step ST604, the scheduling information for the Remaining Minimum SI (RMSI) can be obtained. In NR mode, in step ST605, the receiving RMSI can be set.

[0194] The apparatus constituting the core network (hereinafter sometimes referred to as "core network-side apparatus") updates the tracking area list based on the TAU request signal and the identification identifier (UE-ID, etc.) of the communication terminal sent from the communication terminal. The core network-side apparatus sends the updated tracking area list to the communication terminal. The communication terminal rewrites (updates) its own TAC list based on the received tracking area list. Afterward, the communication terminal enters standby mode in the cell.

[0195] The widespread adoption of smartphones and tablets has led to an explosive growth in traffic volume using cellular wireless communication systems, raising concerns about a global shortage of wireless resources. To address this situation and improve frequency utilization efficiency, research has been conducted on cell miniaturization and promoting spatial separation.

[0196] In the existing cell structure, cells composed of eNBs have a wide coverage area. Previously, cells were constructed to cover a specific area by using the wide coverage area of ​​multiple cells consisting of multiple eNBs.

[0197] When cell miniaturization is implemented, cells composed of eNBs have a narrower coverage area compared to cells composed of existing eNBs. Therefore, similar to existing technologies, a large number of miniaturized eNBs are needed to cover a certain area compared to existing eNBs.

[0198] In the following description, as with existing eNBs, cells with larger coverage areas are referred to as "macrocells," and the eNBs that make up macrocells are referred to as "macro eNBs." Furthermore, as with cells that have undergone miniaturization, cells with smaller coverage areas are referred to as "small cells," and the eNBs that make up small cells are referred to as "small eNBs."

[0199] For example, a macro eNB can be a "wide area base station" as described in Non-Patent Document 7.

[0200] Small eNBs can be, for example, low-power nodes, local nodes, and hotspots. Furthermore, small eNBs can be pico eNBs constituting pico cells, femto eNBs constituting femto cells, HeNBs, RRHs (Remote Radio Heads), RRUs (Remote Radio Units), RREs (Remote Radio Equipment), or RNs (Relay Nodes). Additionally, small eNBs can also be "Local Area Base Stations" or "Home Base Stations" as described in Non-Patent Document 7.

[0201] Figure 13 This illustrates an example of a cell structure in NR. In an NR cell, a narrow beam is formed and its direction is changed for transmission. Figure 13In the example shown, base station 750 uses beam 751-1 to transmit and receive data with the mobile terminal at certain times. At other times, base station 750 uses beam 751-2 to transmit and receive data with the mobile terminal. Similarly, base station 750 uses one or more of beams 751-3 to 751-8 to transmit and receive data with the mobile terminal. Thus, base station 750 constitutes a wide-range cell.

[0202] exist Figure 13 The example shown depicts a base station 750 using 8 beams, but the number of beams can be different from 8. Additionally, in... Figure 13 In the example shown, the number of beams used simultaneously by base station 750 is set to one, but it can also be multiple.

[0203] In the connection between the UE and the NR base station (hereinafter sometimes referred to as gNB), multiple TRPs (Transmission Reception Points) under the gNB can be used. For example, Figure 13 The base station 750 in the gNB can be one of the TRPs under the gNB. Furthermore, a TRP can be called a transceiver. These multiple TRPs can be asynchronous with each other. That is, the subframe boundaries of the signals transmitted and received by each TRP can be different. This asynchrony can, for example, be caused by differences in backhaul delays. The gNB can simultaneously transmit and receive with multiple TRPs for its subordinate UEs, or it can transmit and receive with each TRP at different timings. Similarly, the UE can simultaneously transmit and receive with the gNB and with these multiple TRPs, or it can transmit and receive at different timings.

[0204] As another example, the UE can switch the target TRP under the gNB. For instance, if the UE has better communication quality with other TRPs under the same gNB than with the currently connected TRP, this can be used to switch the target TRP to the aforementioned TRP with better communication quality.

[0205] In the above situation, the following problem arises: No method is publicly available for establishing synchronization with the TRP of the new connection. Consequently, the UE cannot establish synchronization with the TRP of the new connection, resulting in the inability to initiate communication with the TRP of the new connection.

[0206] The following are solutions to the above problems.

[0207] When a UE is connected to a TRP, for example during a handover of the TRP connected to the UE, the gNB indicates to the UE the start of random access processing. This indication can be made using L1 / L2 signaling, such as PDCCH. That is, the random access processing can be PDCCH-order Random Access (RA). Thus, for example, the base station can quickly indicate random access to the UE.

[0208] As another example, the indication can be communicated using MAC signaling. Thus, for example, the base station can transmit a large amount of information in the indication. As another example, the indication can be communicated using RRC signaling. Thus, for example, the base station can transmit an even larger amount of information in the indication.

[0209] The gNB can use the TRP of the handover target (e.g., the TRP before the handover) to make this indication, or it can use a different TRP than the handover target. The aforementioned indication using a different TRP than the handover target can be used, for example, when the gNB uses multiple TRPs to communicate with the UE. Thus, for example, compared to the handover target TRP, using a TRP with good communication quality can improve the reliability of the TRP handover indication from the gNB to the UE.

[0210] This instruction can be used for TRP handover within an SCell. The gNB can send this handover instruction from a cell different from the SCell, such as a PCell, PSCell, or an SCell capable of sending PDCCH. The instruction can contain information related to the cell undergoing the TRP handover (e.g., the cell identifier). Thus, for example, the gNB can issue TRP handover instructions for different cells.

[0211] This instruction can be used for inter-cell TRP handover. The gNB can send the handover instruction from the cell before and after the handover, or from a different cell. The instruction can contain information about the cell undergoing the inter-cell TRP handover (e.g., the identifiers of the cell before and / or after the handover). Thus, for example, the gNB can provide an inter-cell TRP handover instruction.

[0212] The gNB can use measurement results from the UE to determine the post-handover TRP. The gNB can determine the beam used for communication with the UE within that TRP. This, for example, ensures the reliability of communication between the UE and gNB after the TRP handover. The measurement results from the UE can be CSI-RS measurements or measurements from the SS module. The gNB can use the signal strength of the aforementioned signals received by the UE, such as RSRP, to determine the post-handover TRP. The gNB can use the reception quality of the aforementioned signals, such as RSRQ, to determine the post-handover TRP. The gNB can use the signal-to-noise ratio (SNR) to determine the post-handover TRP.

[0213] The gNB can instruct the UE to measure the aforementioned signals. This measurement instruction can be performed using RRC signaling. As an example of RRC signaling, the measurement configuration (MeasConfig) described in Non-Patent Document 26 (3GPP TS 38.331V15.2.1) can be used, or other signaling can be used. As another example, the measurement instruction can be performed using MAC signaling, or L1 / L2 signaling. CSI reporting instructions can be used, or other signaling can be used. Thus, for example, the gNB can quickly notify the UE of the measurement instruction.

[0214] The gNB's measurement instruction to the UE may include information related to the TRP (Transfer Reference Point) being measured, such as the TRP's identifier. The gNB's measurement instruction may also include information related to the beam being measured, such as the beam's identifier. Furthermore, the gNB's measurement instruction may include information related to the number of measurement results reported from the UE to the gNB. As another example, the gNB's measurement instruction may include a list of the TRPs and / or beams being measured. Information related to the beam being measured may, for example, be the identifier of the CSI-RS transmitted using that beam, or the identifier of the SS module transmitted using that beam.

[0215] The TRP identifier can be uniquely assigned within the gNB, uniquely assigned within the cell, or assigned to each UE, such as for each Virtual Cell ID. The TRP identifier can include the cell identifier, the UE identifier, or the Virtual Cell ID. The beam identifier can be the same as the TRP identifier or uniquely assigned within the TRP. The beam identifier can include the TRP identifier.

[0216] The UE can report measurement results to the gNB. This report may include information related to the measured TRP. It may include information related to the beam within the TRP, such as the CSI-RS identifier and / or SS module identifier within the beam. The report may include the received signal strength, reception quality, and / or signal-to-noise ratio of the beam. The report may include the measurement results of the currently connected TRP and / or beam. The aforementioned currently connected TRP and / or beam may be a TRP and / or beam that is the object of measurement but not included in the measurement instruction from the gNB to the UE. Even if not included in the object of measurement in the measurement instruction, the UE can still perform measurements of the currently connected TRP and / or beam velocity. Thus, for example, the gNB can, through the UE, select the most appropriate TRP and / or beam that also includes the currently connected TRP and / or beam as the connection target.

[0217] The reporting of the above measurement results can, for example, use RRC signaling. As an example of using RRC signaling, a measurement report as described in Non-Patent Document 26 (3GPP TS 38.331V15.2.1) can be used, or other signaling methods can be used. As another example, MAC signaling or L1 / L2 signaling can be used. As an example of using L1 / L2 signaling, CSI reporting can be used. The aforementioned CSI report can be included in PUCCH or PUSCH. The aforementioned CSI report can be a periodic CSI report, a semi-permanent CSI report, or a non-periodic CSI report. As another example, RACH or SRS can be used. As an example of using RACH, information about the measurement results can be included as a sequence of RACH preambles. As an example of using SRS, information related to the TRP and / or beam of the measured object can be included as a resource for the time and / or frequency of the SRS, information on the measurement results can be included as a resource for the time and / or frequency of the SRS, information on the measurement results can be included as a sequence of the SRS, or a combination thereof.

[0218] The beam identifier can be unique within the gNB. The gNB can broadcast or individually notify its subordinate UEs of information related to the TRP and beam correspondence. The UE can include the beam identifier in the measurement results report. This, for example, can reduce the signaling volume in the report. This notification can use, for example, RRC-specific signaling, MAC signaling, or L1 / L2 signaling.

[0219] As another example, the beam identifier can be unique within the TRP. The UE can include the TRP identifier in the measurement results report and notify the gNB. This, for example, increases the number of beams that can be supported within a TRP, resulting in improved flexibility in the communication system. The gNB can broadcast or individually notify the UE of information related to the TRP identifier. This broadcast can, for example, use PBCH, RMSI (Remaining System Information), or other system information. The notification can, for example, use RRC-specific signaling, MAC signaling, or L1 / L2 signaling.

[0220] As another example of determining the post-handover TRP, the UE can notify the gNB of a list of candidate post-handover TRPs. The gNB can then select the post-handover TRP from this list. The gNB can then notify the UE of the selected TRP. This notification can, for example, be in the same manner as the gNB using measurement results notifications from the UE to determine the post-handover TRP. Thus, for example, the gNB can use the load condition of the TRP to select the post-handover TRP, resulting in efficient use of the communication system.

[0221] The UE can perform measurements of surrounding TRPs that include the target TRP. This measurement can be performed using a measurement instruction from the gNB, or it can be performed without such an instruction. For example, the measurement can be performed periodically or under specified conditions. These conditions can be, for example, conditions related to the communication quality between the connected TRPs. These conditions can use a threshold related to the receive error rate (e.g., BER or BLER) in communication with the connected TRP, a threshold related to the RSRP of RS transmitted from that TRP, a threshold related to RSRQ, or a threshold related to SINR. The RS can be, for example, a DMRS, a CSI-RS, or a PTRS. An SS module can be used instead of the RS. These conditions can be, for example, conditions where the UE begins the measurement when the communication quality in the UE becomes below or less than the aforementioned threshold. Thus, for example, it is possible to ensure the communication quality between the UE and the gNB and reduce the signaling volume between the UE and the gNB.

[0222] The thresholds mentioned above can be predetermined by standards, or they can be broadcast or notified to the UE from the gNB. This notification can be made using, for example, RRC signaling, MAC signaling, or L1 / L2 signaling.

[0223] As a method for selecting the candidate in the UE, the RSRP of the signal received from the surrounding TRPs can be used, RSRQ can be used, SINR can be used, or a combination of them can be used. For example, a predetermined number of TRPs and / or beams can be selected as candidates in descending order of RSRP, or TRPs and / or beams that are RSRPs above or exceeding a predetermined threshold can be selected as candidates. Alternatively, for example, among the TRPs and / or beams that are RSRPs above or exceeding the aforementioned predetermined threshold, TRPs and / or beams up to a predetermined number can be selected as candidates in descending order of RSRP, RSRQ, or SINR. This, for example, can prevent an increase in signaling volume between the UE and the gNB. In the above, regardless of whether it is above or exceeding the predetermined threshold, the lowest TRP and / or beam can be selected as the candidate.

[0224] The threshold used for selecting the candidate can be the same as or different from the threshold used to start the measurement for the UE. The method for determining the threshold used for selecting the candidate can also be the same as the threshold used to start the measurement for the UE, and the same method can be used to broadcast or notify the UE. This, for example, avoids design complexity in the communication system.

[0225] The predetermined quantity mentioned above can be determined by standards, or it can be broadcast or notified to the UE from the gNB. This notification can be made using, for example, RRC signaling, MAC signaling, or L1 / L2 signaling.

[0226] As another example of determining the TRP after handover, the UE can determine the TRP after handover. For example, the UE can determine the surrounding TRPs that include the target TRP. This determination can be performed using a determination indication from the gNB, or it can be performed periodically without such an indication, or it can be performed using a TRP handover indication from the gNB to the UE. In the TRP handover indication from the gNB to the UE, there can be no information related to the target TRP. The UE can notify the gNB of information related to the determined TRP. This indication can include information related to the beam in the TRP. The beam-related information can be, for example, the CSI-RS identifier and / or SS module identifier in the beam. This notification can be performed using RRC signaling, MAC signaling, L1 / L2 signaling, or a combination thereof. For example, by using MAC signaling and / or L1 / L2 signaling, the UE can quickly notify the gNB of information related to the determined TRP to the base station.

[0227] The UE can use the signal strength of the aforementioned signals received by the UE, such as RSRP, to determine the TRP after handover. The UE can use the reception quality of the aforementioned signals, such as RSRQ, to determine the TRP after handover. The UE can use the signal-to-noise ratio to determine the TRP after handover. Therefore, for example, the reliability of communication between the UE and the gNB after TRP handover can be improved.

[0228] As an example of the information contained in the random access start instruction from gNB to UE, the following (1) to (14) are disclosed.

[0229] (1) Information related to the TRP of the new connection.

[0230] (2) This indicates that the connection to the TRP being connected has been severed.

[0231] (3) Information related to the TRP that disconnects the connection.

[0232] (4) Information related to the TRP for maintaining the connection.

[0233] (5) Information related to the candidates for the new TRP connection.

[0234] (6) Information related to the timing of PRACH transmission to the connection target TRP.

[0235] (7) Information related to the preamble of the PRACH used to connect to the target TRP.

[0236] (8) Information related to the synchronization or asynchrony between the TRP before and after the handover.

[0237] (9) Information related to the frame timing of the TRP after the switch.

[0238] (10) Information related to the return delay of the TRP after the switch.

[0239] (11) Information relating to the main TRP after the TRP switch (refer to non-patent literature 27).

[0240] (12) Information relating to the main and / or auxiliary PDCCH after the TRP switch (see Non-Patent Document 27).

[0241] (13) Scheduling information for UE.

[0242] (14) The combination of (1) to (13) above.

[0243] The information in (1) above could be, for example, the identifier of the TRP of the connection target, or information related to the beam used by that TRP. As information about the beam, for example, information related to the SS module could be used, information related to the CSI-RS could be used, or both could be used. The information in (1) above contains information about the beam, so, for example, the UE can quickly capture the beam of the connection target. The information related to the SS module could be, for example, the identifier of the SS module. The information related to the CSI-RS could be, for example, the identifier of the CSI-RS resource.

[0244] The information in (1) above can be one or multiple. For example, when multiple TRPs are added as connection targets in the UE, the information in (1) above can be set to multiple. Even when multiple beams are added, they can be set to the same. In the case of adding multiple beams as described above, the TRP of the connection target can be one or multiple. Thus, for example, the signaling volume from the base station to the UE can be reduced when multiple TRPs and / or beams are added as connection targets of the UE.

[0245] The information in (1) above may include information related to the number of TRPs and / or beams of the connection target. Thus, for example, the UE can quickly obtain the number of TRPs and / or beams of the connection target, resulting in the UE being able to quickly perform connection processing for the TRPs and / or beams.

[0246] The information in (1) above may only be the number of TRPs and / or beams of the connection target. For example, the UE can determine the number of TRPs and / or beams from the transmittable and receiveable TRPs and / or beams as new connection targets. When determining new connection target TRPs and / or beams, the UE can use the strength of the signal received from the TRP and / or beam, or use the PRACH transmission timing for that TRP and / or beam, or use other indicators (e.g., the signal-to-noise ratio of the received signal). Thus, for example, the UE can use TRPs and / or beams with higher communication quality to communicate with the base station, resulting in improved communication quality between the UE and the base station. In addition, for example, the UE can use TRPs and / or beams with earlier PRACH transmission timing, resulting in the ability to switch or add faster TRPs and / or beams in the UE.

[0247] Regarding (2) above, the UE can use this information to determine whether to switch or add a TRP connected to the UE. For example, if the information in (2) above indicates that the connection has not been severed, the UE can use this information to add the connected TRP. Thus, for example, the UE can quickly determine whether to add or switch the TRP of the connection target.

[0248] The information in (3) above can be the same as the information in (1) above. For example, the information can be related to the TRP and / or beam before the handover, such as the TRP and / or beam that disconnects the connection with the UE, or it can include information related to the number of the TRP and / or beam. Thus, for example, the same effect as in (1) above can be obtained.

[0249] The information in (3) above can be communicated to the UE from the gNB using signaling different from that of the random access start indication. For example, this information can be sent from the gNB to the UE as a TRP release indication. Thus, for example, in the case of releasing only the connection TRP, it is not necessary to send a random access start indication from the gNB to the UE, resulting in a reduction in the amount of signaling between the gNB and the UE.

[0250] The TRP release indication can be, for example, L1 / L2 signaling. This allows for rapid notification from the gNB to the UE. As other examples, the signaling can be MAC signaling or RRC signaling. This allows for the notification of large amounts of information.

[0251] The information in (4) above can be the same as the information in (1) above. For example, the information can be related to the TRP and / or beams that maintain the connection with the UE, or it can include information related to the number of the TRP and / or beams. Thus, for example, the same effect as in (1) above can be obtained.

[0252] The information in (4) above can also be the same as that in (3) above, and can be notified to the UE from the gNB using signaling different from that of the random access start indication. For example, the TRP release indication above can include the information in (4) above.

[0253] The information in (5) above can be the same as the information in (1) above. For example, this information can be related to the TRP and / or beam that is a candidate for connection with the UE. The UE can select the TRP and / or beam for a new connection from the TRP and / or beam of the connection target included in (5) above. The UE can select the number of TRPs and / or beams included in (1) above. When deciding on a new connection target TRP and / or beam, the UE can use a method related to the information in (1) above and disclosed therein. Thus, for example, the UE can select a TRP and / or beam with higher communication quality and / or earlier PRACH transmission timing. As a result, the communication quality between the UE and the base station can be improved. In addition, for example, a fast TRP and / or beam can be switched and / or added to the UE.

[0254] The information mentioned in (6) above could be, for example, information related to the timing of the UE sending a PRACH to the TRP and / or beam after the handover. The UE can use this information to send a PRACH to the TRP and / or beam of the connection target. Thus, the UE can quickly perform random access processing on the TRP and / or beam of the connection target.

[0255] As another example, the information in (6) above could be information indicating the correspondence between SS modules and PRACH transmission timings (e.g., PRACH occasions) in the TRP after handover. The SS modules in this information could, for example, be an SS module index (SSB index). By obtaining this information, the UE can avoid obtaining the system information in the TRP after handover. Thus, for example, the UE can quickly perform TRP handover.

[0256] As another example, the UE can obtain the information described in (6) above based on broadcast information from the gNB. This broadcast information can also be sent, for example, from the TRP of the connection target. Thus, for example, the signaling volume of random access instructions from the gNB to the UE can be reduced.

[0257] The preamble contained in the information in (7) above can be set as a preamble provided separately to the UE. The UE can use the information of the notified RA preamble to start random access processing with the newly connected TRP and / or beam. Thus, random access processing between the UE and gNB can be performed quickly.

[0258] The preamble contained in the information in (7) above can be uniquely given in the TRP or uniquely given in each beam used by the TRP. Thus, for example, it can prevent the depletion of the RA preamble, resulting in an increase in the number of UEs that can be accommodated.

[0259] As another example, the preamble contained in the information in (7) above can be uniquely given in the gNB. Based on the information in the preamble contained in (7) above, the TRP and / or beam to which the UE will connect can be uniquely determined. Thus, for example, the signaling amount in the random access instruction from the base station to the UE can be reduced.

[0260] As another example, the information in (7) above could be information representing the correspondence between SS modules and preambles in the TRP after handover. The SS modules in this information could, for example, be an SS module index (SSB index). By obtaining this information, the UE can avoid obtaining the system information in the TRP after handover. Thus, for example, the UE can quickly perform TRP handover.

[0261] As another example relating to the RA preamble used for UE and gNB connection, the RA preamble can be uniquely determined based on the information relating to (1) above. Thus, for example, the signaling amount in the random access indication from the base station to the UE can be reduced.

[0262] The information in (8) above can be, for example, information measured by the gNB, or information measured by the UE and reported to the gNB. Using the information in (8) above, for example, if the TRP before and after the handover are synchronized, the UE can avoid performing random access processing on the TRP after the handover. Thus, for example, the TRP handover in the UE can be performed quickly.

[0263] The information mentioned in (9) above could be, for example, information related to the difference in frame timing between the pre-handover TRP and the post-handover TRP. This information could be, for example, information determined by the gNB, or information determined by the UE and reported to the gNB. The UE can use this information to send PRACH at the PRACH receive timing of the post-handover TRP. Thus, for example, the UE does not need to wait for the SS module from the post-handover TRP, resulting in the UE being able to quickly perform RACH transmission to the post-handover TRP.

[0264] The information mentioned in (10) above could be, for example, information related to the difference between the backhaul delay in the pre-handover TRP and the post-handover TRP. This information could be, for example, information measured by the gNB, or information measured by the UE and reported to the gNB. The UE can use this information to send a PRACH to the post-handover TRP. Thus, for example, the value of TA (Timing Advance) in the RA response can be reduced, resulting in a reduction in the processing load of the UE after receiving the RA response.

[0265] The information in (11) above could be, for example, an identifier of the primary TRP. As another example, the information in (11) above could be an identifier indicating whether a primary TRP has been switched over, or an identifier indicating whether the TRP is the primary TRP after the switch. The gNB and UE can determine that any TRP other than this one is a secondary TRP. The UE can use the information related to (11) above to switch the primary TRP. Thus, for example, when a primary TRP is set for the UE, the UE can quickly perform the primary TRP switch.

[0266] The information in (12) above could be, for example, the identifier of the TRP that transmits the main PDCCH and / or the secondary PDCCH. There can be one or more TRP identifiers. There may be no identifier for the TRP that transmits the secondary PDCCH. If there is no identifier for the TRP that transmits the secondary PDCCH, the secondary PDCCH may not be transmitted. The information in (12) above may not include the identifier of the main TRP. The main PDCCH can be transmitted from at least the main TRP. The UE can use the information in (12) above to perform the receiving operation of the main PDCCH and / or the secondary PDCCH. The UE can stop receiving TRPs not included in the information in (12) above. Therefore, for example, power consumption in the UE can be reduced.

[0267] The information in (13) above could be, for example, the scheduling information for the UE's transmission and reception between itself and the TRP after handover. The UE can use the information in (13) above to transmit and receive signals and / or data with the TRP after handover. Thus, for example, after establishing synchronization with the TRP after handover, the UE can quickly perform data transmission and reception.

[0268] As another example related to the information in (13) above, this information can be included in the RA response. Thus, for example, after the UE establishes synchronization with the post-handover TRP, it can quickly perform data transmission and reception, and the communication environment of the UE during the TRP handover can be reflected in the scheduling. This improves the efficiency of the communication system's transmission and reception.

[0269] As another example relating to the information in (13) above, this information may be included in both the random access indication and the RA response. For example, information relating to periodic and / or semi-permanent scheduling may be included in the random access indication, and information relating to dynamic scheduling may be included in the RA response. Thus, for example, the UE can quickly perform data transmission and reception after establishing synchronization with the post-handover TRP, and can reduce the signaling volume in the RA response.

[0270] Regarding the information in (13) above, the main PDCCH can contain information about the scheduled PDSCH, PUCCH, PUSCH, and SRS. The PDSCH, PUCCH, PUSCH, and / or SRS information can include information about the TRP used for transmitting and receiving the channel and / or signal, such as the TRP's identifier. The information in the PDSCH, PUCCH, PUSCH, and / or SRS can contain multiple TRPs. The UE can use the information in (13) above to transmit and receive the channel and / or signal. Therefore, for example, flexible scheduling is possible in communications using multiple TRPs.

[0271] The UE uses a random access indication from the gNB to perform random access with the target TRP. The UE can use the frame timing of the post-handover TRP to initiate random access processing. The UE can use this random access indication to establish downlink synchronization with the post-handover TRP. The UE can use the reception of SS modules sent from the target TRP to establish this downlink synchronization. This, for example, can prevent interference in the post-handover TRP. The UE can pre-acquire downlink synchronization with the target TRP. For example, the UE can maintain the downlink synchronization established during the determination of the target TRP. This determination can be, for example, a CSI-RS determination or an SS module determination. This, for example, allows the UE to quickly send PRACH to the gNB.

[0272] As another example, the UE can use the frame timing of the pre-handover TRP to begin random access processing. The UE can use the information related to (9) above to derive the frame timing of the post-handover TRP. The UE can use the derived frame timing to send PRACH at the PRACH receive timing of the post-handover TRP. Thus, for example, the UE does not need to wait for an SS burst from the post-handover TRP, resulting in the UE being able to quickly perform RACH transmission to the post-handover TRP.

[0273] When performing random access processing, the UE can obtain system information from the gNB. The UE can use this system information to obtain the PRACH transmission timing (e.g., PRACH occasion). Thus, for example, the gNB does not need to separately notify the UE of the information mentioned in (6), which reduces the signaling volume between the gNB and the UE.

[0274] As another example, the UE can obtain system information from the gNB during random access processing. The gNB notifies the UE of the information described in (6) above. The UE can use the information described in (6) above to obtain the PRACH transmission timing (e.g., PRACH occasion). Thus, for example, the UE does not need to obtain system information, and as a result, the UE can quickly perform random access.

[0275] The gNB can notify the UE of the information in (7) above in advance. The UE can use the preamble contained in the information in (7) above to perform random access processing. Thus, for example, it can prevent conflicts with other UEs in random access, and as a result, the UE can quickly perform random access.

[0276] The mapping between SS modules and PRACH transmittable timings can be uniquely defined within a TRP. For example, this mapping can differ between TRPs. This allows for flexible allocation of PRACH transmittable timings within the gNB, for instance.

[0277] As another example, the correspondence between SS modules and PRACH transmittable timings can be uniquely given within the cell. That is, this correspondence can be unique across TRPs. This, for example, avoids complexity in the communication system.

[0278] The system information sent from the gNB can be different for each TRP of the sending source. For example, the system information can be only system information related to that TRP. The system information related to that TRP can, for example, include the correspondence between the aforementioned SS modules and the PRACH transmittable timing in that TRP. Thus, for example, the amount of system information sent by the gNB can be reduced.

[0279] As another example, system messages sent from the gNB may contain all or part of the TRP-related system information belonging to the gNB. This TRP-related system information may, for example, include the correspondence between the aforementioned SS modules and the PRACH transmittable timings within that TRP. Thus, for example, the UE can obtain the system information used in the target TRP during TRP handover, allowing the UE to quickly perform the TRP handover.

[0280] The UE can use a random access instruction from the gNB to stop transmitting and receiving signals and / or data via the pre-handover TRP. The UE can use an RA response received from the gNB via the post-handover TRP to resume transmitting and receiving signals and / or data via the post-handover TRP. The gNB can also be configured similarly. Thus, for example, interference to the pre-handover and / or post-handover TRPs can be prevented during TRP handover.

[0281] The UE can send a HARQ response to the random access indication from the gNB to the pre-handover TRP. This HARQ response can be sent, for example, when the random access indication is given using RRC signaling and / or MAC signaling. Thus, for example, even if the HARQ decoding result of the signaling in the UE is NG, the UE can still notify the gNB of the HARQ-Nack, and the gNB can retransmit the random access indication to the UE.

[0282] The UE can send a HARQ response to downlink data from the gNB to the pre-handover TRP. The transmission of the HARQ response to the pre-handover TRP can, for example, occur before sending the HARQ response to the aforementioned random access indication. Thus, for example, even if the HARQ decoding result of the downlink data in the UE is NG, the UE can still notify the gNB of the HARQ-Nack, and the gNB can retransmit the downlink data to the UE.

[0283] The UE can send a HARQ response to downlink data from the gNB to the post-handover TRP. The transmission of the HARQ response to the post-handover TRP can, for example, be performed after sending the HARQ response to the aforementioned random access indication. The UE can retain this HARQ response until the PRACH transmission timing for the post-handover TRP is reached. Thus, for example, the same effect as described above can be achieved.

[0284] The UE can receive a HARQ response for uplink data to the gNB via the pre-handover TRP. Reception of the HARQ response from the pre-handover TRP can, for example, occur before sending the HARQ response for the aforementioned random access indication. Thus, for example, even if the HARQ decoding result of the uplink data in the gNB is NG, the UE can still receive a HARQ-Nack from the gNB, and the UE can retransmit the uplink data to the gNB.

[0285] The UE can receive a HARQ response for uplink data to the gNB via the post-handover TRP. Receiving the HARQ response from the post-handover TRP can, for example, be performed before sending the HARQ response for the aforementioned random access indication. The UE can retain the reception of this HARQ response until after the RA response reception time from the post-handover TRP. Thus, for example, the same effect as described above can be achieved.

[0286] As another example, the UE may not assume downlink data reception after or following the random access indication. The UE may not receive downlink data after or following the random access indication. Downlink data transmission to the UE can resume after the RA response from the post-handover TRP. This, for example, avoids design complexities in the communication system.

[0287] As another example, the UE may not transmit uplink data after or following the random access indication. Uplink data transmission from the UE can resume after the RA response from the post-handover TRP. This, for example, avoids design complexities in the communication system.

[0288] The UE can reselect or redetermine the target TRP for connection. This action can be performed, for example, if the UE fails to complete the handover process for the subsequent TRP. This handover failure could be due to a failure of random access processing or a capture failure of the SS module. During the reselection or redetermination of the target TRP, the UE can notify the gNB of the handover failure by including information indicating that the TRP handover process failed. This, for example, avoids a situation where communication between the gNB and the UE is impossible in the event of a TRP handover failure. As a result, robustness in the communication system can be improved.

[0289] Figure 14 and Figure 15 This is a diagram illustrating the actions of switching the UE's connection TRP. Figure 14 and Figure 15 Connect at the boundary line BL1415. Figure 14 and Figure 15 In the example shown, the TRP connected to the UE is switched from TRP#1 to TRP#2. Additionally, Figure 14 and Figure 15 An example is shown where the UE measures the CSI-RS, and the gNB uses the measurement result to determine the action in the case of connecting to the target TRP.

[0290] exist Figure 14 In steps ST1401 and ST1402, uplink / downlink data is transmitted and received between the UE and gNB via TRP#1. Step ST1401 shows the data transmission and reception between the UE and TRP#1, and step ST1402 shows the data transmission and reception between TRP#1 and gNB.

[0291] exist Figure 14 In steps ST1405 and ST1406, the gNB instructs the UE to perform CSI-RS measurements via TRP#1. Step ST1405 shows the measurement instruction from the gNB to TRP#1, and step ST1406 shows the measurement instruction from TRP#1 to the UE. The measurement instructions shown in steps ST1405 and ST1406 can be performed using RRC signaling, MAC signaling, or L1 / L2 signaling.

[0292] exist Figure 14In steps ST1410 and ST1411, TRP#1 and TRP#2 send CSI-RS to the UE. Step ST1410 shows the CSI-RS transmission from TRP#1, and step ST1411 shows the CSI-RS transmission from TRP#2. In step ST1413, the UE receives the CSI-RS shown in steps ST1410 and ST1411 and measures the signal.

[0293] exist Figure 14 In steps ST1415 and ST1416, the UE notifies the gNB of the CSI-RS measurement results via TRP#1. Step ST1415 shows the measurement result notification from the UE to TRP#1, and step ST1416 shows the measurement result notification from TRP#1 to the gNB. The measurement result notification shown in steps ST1415 and ST1416 can be performed using RRC signaling, MAC signaling, or L1 / L2 signaling.

[0294] exist Figure 14 In step ST1420, the gNB uses the measurement result from step ST1416 to determine whether to switch the UE's connection target TRP from TRP#1 to TRP#2.

[0295] exist Figure 14 In steps ST1425 and ST1426, the gNB indicates the start of RACH to the UE via TRP#1. Step ST1425 shows this indication from the gNB to TRP#1, and step ST1426 shows this indication from TRP#1 to the UE. This indication can be transmitted using PDCCH. The indication contains information indicating a handover from TRP#1 to TRP#2. The indication may contain information related to the RA preamble. The UE uses step ST1426 to... Figure 15 In step ST1427, the connection to TRP#1 is released. Additionally, in Figure 15 In step ST1428 shown, the SS module is sent from TRP#2 to the UE. Figure 15 In step ST1429, the UE uses the SS module from step ST1428 to establish downlink synchronization with TRP#2. After sending an indication in step ST1425, the gNB stops transmitting downlink data via TRP#1. After receiving an indication in step ST1426, the UE stops transmitting uplink data via TRP#1.

[0296] exist Figure 15In steps ST1430 and ST1431, the UE sends a PRACH to the gNB via TRP#2. Step ST1430 shows the PRACH transmission from the UE to TRP#2, and step ST1431 shows the PRACH transmission from TRP#2 to the gNB. The RA preamble in this PRACH transmission can be the same as the RA preamble included in step ST1426, or it can be different.

[0297] exist Figure 15 In steps ST1435 and ST1436, the gNB notifies the UE of the random access response via TRP#2. Step ST1435 shows the random access response notification from the gNB to TRP#2, and step ST1436 shows the random access response notification from TRP#2 to the UE. The UE uses this response to establish uplink synchronization with TRP#2. After sending the indication in step ST1435, the gNB stops transmitting downlink data via TRP#2. After receiving the indication in step ST1436, the UE stops transmitting uplink data via TRP#2.

[0298] exist Figure 15 In steps ST1440 and ST1441, uplink / downlink data is transmitted and received between the UE and gNB via TRP#2. Step ST1440 shows the data transmission and reception between the UE and TRP#2, and step ST1441 shows the data transmission and reception between TRP#2 and gNB.

[0299] Figure 14 and Figure 15 An example of CSI-RS measurement is shown, but SS module measurement can also be performed. The gNB can instruct the UE to perform SS module measurement in steps ST1405 and ST1406. The UE can notify the gNB of the SS module measurement results in steps ST1415 and ST1416. Thus, for example, the UE can directly use the signal used for TRP synchronization of the measurement target as the measurement target, and therefore the measurement can be performed quickly in the UE.

[0300] exist Figure 14 and Figure 15 The diagram illustrates an example of releasing the TRP#1 connection in the UE as shown in step ST1427, prior to the PRACH transmission in step ST1430. However, the TRP#1 connection can also be released after the random access response in step ST1436. Thus, for example, even if the UE fails to connect to TRP#2, the UE can continue its connection to TRP#1, resulting in improved reliability of the communication system.

[0301] exist Figure 14 and Figure 15The diagram illustrates an example of the UE establishing uplink synchronization after the random access response in step ST1436, but the UE can also send random access message 3 to the gNB. The gNB can send random access message 4 to the UE. The sending and receiving of random access messages 3 and 4 described above can be applied, for example, if the UE uses a different RA preamble than the one notified from the gNB in ​​step ST1431. Thus, for example, contention-based random access can be performed during TRP handover between the UE and the gNB, resulting in an increase in the number of UEs that can be accommodated in the gNB.

[0302] Other solutions are disclosed. During the handover of the TRP to which the UE is connected, the UE autonomously initiates random access processing. That is, the UE can initiate random access processing without the aforementioned random access indication sent from the gNB. The aforementioned random access indication could, for example, be a TRP handover indication.

[0303] The gNB can choose not to reject a UE's autonomous random access procedure. Subsequently, the base station's TRP handover indication and / or TRP release indication to the UE can be treated as a rejection action by the gNB for that autonomous random access procedure. This, for example, improves the flexibility of the communication system.

[0304] As another example, the gNB can reject a UE's autonomous random access process. This response could, for example, be one that is not initiated during a pre-determined period for the RA response. This, for example, avoids design complexities in the communication system.

[0305] The random access process described above can be a contention-free random access. That is, the UE can use a pre-assigned RA preamble from the gNB. This allows for, for example, rapid completion of the random access process. As another example, the random access process described above can be a contention-based random access. This, for example, prevents the depletion of RA preamble resources in the gNB, resulting in an increase in the number of UEs that can be accommodated in the gNB.

[0306] The method disclosed in Embodiment 1 can be applied to the handover of TRPs when the UE is transmitting and receiving with multiple TRPs. The TRPs being switched can be one or more. When switching multiple TRPs, the TRPs can be switched one by one, or multiple TRPs can be switched at once. For example, by switching multiple TRPs at once, the TRP handover can be performed quickly.

[0307] The UE can notify the gNB of information related to the combination of TRPs that the primary UE can communicate with simultaneously. This information may be related to the combination of beams that the primary UE can communicate with simultaneously. The UE can include this information in the signaling of the aforementioned measurement result report, or it can use different signaling to notify the UE. The gNB can use this information to determine the handover target TRP in the UE. Thus, for example, the gNB can more easily determine the TRPs that the UE can communicate with simultaneously. As a result, the communication rate between the UE and the gNB can be improved, and the reliability between the UE and the gNB can be improved.

[0308] When the gNB notifies the UE of the TRP handover indication, for example, a TRP for PCell communication, a TRP for PSCell communication, or a TRP for SCell communication that can send PDCCH can be used.

[0309] Figure 16 and Figure 17 This diagram illustrates the action of a UE switching connection TRPs when connected to multiple TRPs. Figure 16 and Figure 17 Connect at the boundary line BL1617. Figure 16 and Figure 17 In the example shown, the TRP connected to the UE changes from TRP#1, TRP#2 to TRP#1, TRP#3. Additionally, Figure 16 and Figure 17 This illustrates an example of the UE determining the CSI-RS, and the gNB using this determination to determine the action to be taken in a situation where the target TRP is connected. Figure 16 and Figure 17 In the middle, to and Figure 14 and Figure 15 Common parts are labeled with the same number, and the common description is omitted.

[0310] Figure 16 Steps ST1401, ST1402 and Figure 14 same.

[0311] exist Figure 16 In steps ST1501 and ST1502, uplink / downlink data is transmitted and received between the UE and gNB via TRP#2. Step ST1501 shows the data transmission and reception between the UE and TRP#2, and step ST1502 shows the data transmission and reception between TRP#2 and gNB.

[0312] Figure 16 Steps ST1405 to ST1411 and Figure 14 same.

[0313] exist Figure 16In step ST1503, TRP#3 sends CSI-RS to the UE. In step ST1413, the UE receives the CSI-RS shown in steps ST1410, ST1411, and ST1503 and measures the signal.

[0314] Figure 16 Steps ST1415, ST1416 and Figure 14 same.

[0315] exist Figure 16 In step ST1504, the gNB uses the measurement results from step ST1416 to determine whether to switch the UE’s connection target TRP from TRP#1, TRP#2 to TRP#1, TRP#3.

[0316] exist Figure 16 In steps ST1505 and ST1506, the gNB notifies the UE of the instruction to release TRP#2 via TRP#1. Step ST1505 shows this instruction from the gNB to TRP#1, and step ST1506 shows this instruction from TRP#1 to the UE. This instruction can be transmitted using PDCCH. The UE uses step ST1506 to... Figure 17 In step ST1527 shown, the connection with TRP#2 is released.

[0317] exist Figure 17 In steps ST1525 and ST1526, the gNB instructs the UE to begin RACH via TRP#1. Step ST1525 shows this instruction from the gNB to TRP#1, and step ST1526 shows this instruction from TRP#1 to the UE. This instruction can be transmitted using PDCCH. The instruction includes information indicating the appending of TRP#3. The instruction may include information related to the RA preamble. The UE uses step ST1526 to... Figure 17 The step ST1528 shown indicates the start of the SS module reception operation from TRP#3 to the UE. Figure 17 In step ST1529, the UE uses the SS module from step ST1528 to establish downlink synchronization with TRP#3.

[0318] exist Figure 17 In steps ST1507 and ST1508, the UE sends a PRACH to the gNB via TRP#3. Step ST1507 shows the PRACH transmission from the UE to TRP#3, and step ST1508 shows the PRACH transmission from TRP#3 to the gNB. The RA preamble in this PRACH transmission can be the same as the RA preamble included in step ST1526, or it can be different.

[0319] exist Figure 17 In steps ST1509 and ST1510, the gNB notifies the UE of a random access response via TRP#3. Step ST1509 shows the random access response notification from the gNB to TRP#3, and step ST1510 shows the random access response notification from TRP#3 to the UE. The UE uses this response to establish uplink synchronization with TRP#3. After sending the indication in step ST1509, the gNB begins downlink data transmission via TRP#3. After receiving the response in step ST1510, the UE begins uplink data transmission via TRP#3.

[0320] exist Figure 17 In steps ST1511 and ST1512, uplink / downlink data is transmitted and received between the UE and gNB via TRP#1. Step ST1511 shows the data transmission and reception between the UE and TRP#1, and step ST1512 shows the data transmission and reception between TRP#1 and gNB.

[0321] exist Figure 17 In steps ST1513 and ST1514, uplink / downlink data is transmitted and received between the UE and gNB via TRP#3. Step ST1513 shows the data transmission and reception between the UE and TRP#3, and step ST1514 shows the data transmission and reception between TRP#3 and gNB.

[0322] Figure 16 and Figure 17 An example of CSI-RS measurement is shown, but SS module measurement can also be performed. The gNB can instruct the UE to perform SS module measurement in steps ST1405 and ST1406. The UE can notify the gNB of the SS module measurement results in steps ST1415 and ST1416. Thus, for example, the UE can directly use the signal used for TRP synchronization of the measurement target as the measurement target, and therefore the measurement can be performed quickly in the UE.

[0323] exist Figure 16 and Figure 17The diagram illustrates an example where, prior to the RACH transmission indications in steps ST1525 and ST1526, the instruction to release TRP#2 from the gNB to the UE, as shown in steps ST1505 and ST1506, and the release of the TRP#2 connection in the UE, as shown in step ST1527, are performed. However, the instruction to release TRP#2 from the gNB to the UE and the release of the TRP#2 connection in the UE can also be performed after the random access response in steps ST1509 and ST1510. Thus, for example, even if the connection between the UE and TRP#3 fails, the UE can continue its connection with TRP#2, resulting in improved reliability of the communication system.

[0324] exist Figure 16 and Figure 17 The diagram illustrates an example of the UE establishing uplink synchronization after the random access response in step ST1510, but the UE can also send random access message 3 to the gNB. The gNB can send random access message 4 to the UE. The sending and receiving of the aforementioned random access messages 3 and 4 can, for example, be applied when the UE uses an RA preamble different from the RA preamble notified from the gNB in ​​step ST1508. Thus, for example, contention-based random access can be performed during TRP handover between the UE and the gNB, resulting in an increase in the number of UEs that can be accommodated in the gNB.

[0325] exist Figure 16 and Figure 17 In the example shown in steps ST1505 and ST1506, the release of TRP#2 is illustrated via TRP#1, but it can also be performed via TRP#2. Thus, for example, the gNB and UE can use the resources of TRP#1 to send and receive data, resulting in improved efficiency in the communication system.

[0326] During TRP handover in a UE connected to multiple TRPs, the UE can perform autonomous random access processing. In the above, TRP handover can be performed one by one. Furthermore, the TRP before handover can be, for example, a TRP used for PCell communication, a TRP used for PSCell communication, or a SCell capable of transmitting PDCCH. As another example, the PRACH can contain information about the TRP before handover. For example, the RA preamble can be determined using the identifier of the TRP before handover.

[0327] The gNB can choose not to reject a UE's autonomous random access procedure. Subsequently, the base station's TRP handover indication and / or TRP release indication to the UE can be treated as a rejection action by the gNB for that autonomous random access procedure. This, for example, improves the flexibility of the communication system.

[0328] As another example, the gNB can respond to a UE's autonomous random access process. This response could, for example, be to refrain from performing a random access response (RA) for a predetermined period. This, for example, avoids design complexities in the communication system.

[0329] The method disclosed in Embodiment 1 can be applied to adding connection TRPs in a UE. The added TRP can be one or more. When switching multiple TRPs, the TRPs can be switched one by one, or multiple TRPs can be switched at once. For example, by switching multiple TRPs at once, TRP switching can be performed quickly.

[0330] The UE can notify the gNB of information related to the combination of TRPs that can communicate simultaneously with the primary UE. The content of this information and / or the notification method can be the same as those used during TRP handover when the UE is transmitting and receiving with multiple TRPs. Thus, for example, the same effect as described above can be achieved.

[0331] Figure 18 and Figure 19 This is a diagram illustrating the additional actions of the connection TRP in the UE. Figure 18 and Figure 19 Connect at the location of boundary line BL1819. Figure 18 and Figure 19 The example shown illustrates the case where TRP#2 is added as a connection target to a UE already connected to TRP#1. Additionally, Figure 18 and Figure 19 This illustrates an example of the UE measuring CSI-RS, and the gNB using this measurement result to determine the action to add a target TRP for the connection. Figure 18 and Figure 19 In the middle, to and Figure 14 , Figure 15 , Figure 16 as well as Figure 17 Common parts are labeled with the same number, and the common description is omitted.

[0332] Figure 18 Steps ST1401 to ST1416 in the middle Figure 14 same.

[0333] exist Figure 18 In step ST1601 shown, the gNB uses the measurement result of step ST1416 to determine whether to add TRP#2 to the connection target TRP of the UE.

[0334] exist Figure 18In steps ST1625 and ST1626, the gNB instructs the UE to begin RACH via TRP#1. Step ST1625 shows this instruction from the gNB to TRP#1, and step ST1626 shows this instruction from TRP#1 to the UE. This instruction can be transmitted using PDCCH. The instruction includes information indicating the appending of TRP#2. The instruction may include information related to the RA preamble. The UE uses step ST1626 to... Figure 19 The step ST1428 shown indicates the start of the SS module reception operation from TRP#2 to the UE. Figure 19 In step ST1429, the UE uses the SS module from step ST1428 to establish downlink synchronization with TRP#2.

[0335] Figure 19 Steps ST1430, ST1431, ST1435, and ST1436 in the process Figure 15 same.

[0336] Figure 19 The steps ST1511, ST1512 and shown are Figure 17 same. Figure 19 The steps ST1440, ST1441 and shown are Figure 15 same.

[0337] Figure 18 and Figure 19 An example of CSI-RS measurement is shown, but SS module measurement can also be performed. The gNB can instruct the UE to perform SS module measurement in steps ST1405 and ST1406. The UE can notify the gNB of the SS module measurement results in steps ST1415 and ST1416. Thus, for example, the UE can directly use the signal used for TRP synchronization of the measurement target as the measurement target, and therefore the measurement can be performed quickly in the UE.

[0338] exist Figure 18 and Figure 19 The diagram illustrates an example of the UE establishing uplink synchronization after the random access response in step ST1435, but the UE can also send random access message 3 to the gNB. The gNB can send random access message 4 to the UE. The sending and receiving of random access messages 3 and 4 described above can be applied, for example, if the UE uses a different RA preamble than the one notified from the gNB in ​​step ST1431. Thus, for example, contention-based random access can be performed during TRP handover between the UE and the gNB, resulting in an increase in the number of UEs that can be accommodated in the gNB.

[0339] During TRP addition, the UE can perform autonomous random access procedures. In the above, TRP addition can be performed one at a time. Actions performed through the UE's autonomous random access procedures (e.g., TRP handover, TRP addition) can be determined statically via standards, or broadcast or notified to the UE from the gNB. As another example, information related to the action can be included in the PRACH. For example, the RA preamble can be determined using the identifier of the TRP before handover. Thus, for example, the TRP addition process can be executed quickly.

[0340] The gNB can choose not to reject a UE's autonomous random access procedure. Subsequently, the base station's TRP handover indication and / or TRP release indication to the UE can be treated as a rejection action by the gNB for that autonomous random access procedure. This, for example, improves the flexibility of the communication system.

[0341] As another example, the gNB can respond to a UE's autonomous random access process. This response could, for example, be to refrain from performing a random access response (RA) for a predetermined period. This, for example, avoids design complexities in the communication system.

[0342] Figure 20 and Figure 21 This diagram illustrates the summarization and appending of actions of multiple TRPs connected to the UE. Figure 20 and Figure 21 Connect at the location of boundary line BL2021. Figure 20 and Figure 21 The example shown illustrates a scenario where TRP#2 and TRP#3 are added as connection targets to a UE already connected to TRP#1. Additionally, Figure 20 and Figure 21 This illustrates an example of the UE measuring CSI-RS, and the gNB using this measurement result to determine the action to add a target TRP for the connection. Figure 20 and Figure 21 In the middle, to and Figure 14 , Figure 15 , Figure 16 as well as Figure 17 Common parts are labeled with the same number, and the common description is omitted.

[0343] Figure 20 Steps ST1401 to ST1411 in the middle Figure 14 same. Figure 20 Step ST1503 and Figure 16 same. Figure 20 Steps ST1413 to ST1416 and Figure 14 same.

[0344] exist Figure 20 In step ST1701, the gNB uses the measurement results from step ST1416 to determine whether to add TRP#2 and TRP#3 as connection target TRPs for the UE.

[0345] exist Figure 20 In steps ST1725 and ST1726, the gNB instructs the UE to begin RACH via TRP#1. Step ST1725 shows this instruction from the gNB to TRP#1, and step ST1726 shows this instruction from TRP#1 to the UE. This instruction can be transmitted using PDCCH. The instruction contains information indicating the appending of TRP#2 and TRP#3. The instruction may contain information related to the RA preamble. For TRP#2 and TRP#3, the information related to the RA preamble can be different or the same. The UE uses step ST1726 to... Figure 21 The step ST1428 shown indicates the start of the SS module reception operation from TRP#2 to the UE. Figure 21 In step ST1429, the UE uses the SS module from step ST1428 to establish downlink synchronization with TRP#2.

[0346] exist Figure 21 In steps ST1430 and ST1431 shown, the UE sends a PRACH to the gNB via TRP#2. This PRACH transmission is related to... Figure 15 same.

[0347] The UE uses step ST1726, and in step ST1528, it begins receiving the SS module sent from TRP#3 to the UE without waiting. Figure 21 The RA response for steps ST1435 and ST1436 is shown. Figure 21 In step ST1529, the UE uses the SS module from step ST1528 to establish downlink synchronization with TRP#3.

[0348] In steps ST1507 and ST1508, the UE sends a PRACH to the gNB via TRP#3 without waiting. Figure 21 The RA response shown in steps ST1435 and ST1436. This PRACH is sent with... Figure 17 same.

[0349] exist Figure 21 In steps ST1435 and ST1436 shown, the gNB notifies the UE of the random access response via TRP#2. This random access response is related to... Figure 17 same.

[0350] exist Figure 21In steps ST1509 and ST1510 shown, the gNB notifies the UE of the random access response via TRP#3. This random access response is related to... Figure 17 same.

[0351] Figure 21 The steps ST1511, ST1512 and shown are Figure 17 same. Figure 21 The steps ST1440, ST1441 and shown are Figure 15 same. Figure 21 The steps ST1513, ST1514 and shown are Figure 17 same.

[0352] Figure 20 and Figure 21 An example of CSI-RS measurement is shown, but SS module measurement can also be performed. The gNB can instruct the UE to perform SS module measurement in steps ST1405 and ST1406. The UE can notify the gNB of the SS module measurement results in steps ST1415 and ST1416. Thus, for example, the UE can directly use the signal used for TRP synchronization of the measurement target as the measurement target, and therefore the measurement can be performed quickly in the UE.

[0353] exist Figure 20 and Figure 21 The diagram illustrates an example of the UE establishing uplink synchronization after receiving the random access response in steps ST1436 and ST1510. However, the UE can also send random access message 3 to the gNB. The gNB can send random access message 4 to the UE. The sending and receiving of random access messages 3 and 4 can be applied, for example, if the UE uses a different RA preamble than the one notified from the gNB in ​​step ST1726. Thus, for example, contention-based random access can be performed during TRP handover between the UE and the gNB, resulting in an increase in the number of UEs that can be accommodated in the gNB.

[0354] Figure 20 and Figure 21 The diagram illustrates an example where, after the PRACH transmission via TRP#2 shown in steps ST1430 and ST1431, the SS module reception from TRP#3 shown in step ST1428 and the TRP#3 downlink synchronization establishment shown in step ST1529 are performed. However, the SS module reception from TRP#3 and the TRP#3 downlink synchronization establishment can also be performed before the PRACH transmission via TRP#2. Thus, for example, the UE can quickly perform downlink synchronization establishment with TRP#3.

[0355] exist Figure 20 and Figure 21The diagram illustrates an example where, prior to the steps ST1528, ST1529, ST1507, and ST1508 (receiving the SS module from TRP#3, establishing downlink synchronization with TRP#3, and transmitting the PRACH via TRP#3), the steps ST1428 to ST1431 (receiving the SS module from TRP#2, establishing downlink synchronization with TRP#2, and transmitting the PRACH via TRP#2) are performed. However, it is also possible to perform the steps ST1428 to ST1431 (receiving the SS module from TRP#3, establishing downlink synchronization with TRP#3, and transmitting the PRACH via TRP#3) after the steps ST1528, ST1529, ST1507, and ST1508. For example, the subsequent actions described above can be performed when the timing of the SS module transmission from TRP#3 is earlier than the timing of the SS module transmission from TRP#2. Thus, for example, the SS module can send timings based on TRP#2 and TRP#3 to perform rapid TRP appending processing in the UE.

[0356] The method disclosed in Embodiment 1 can be applied to the release of connection TRPs in a UE. The TRPs released as described above can be one or more. When releasing multiple TRPs, they can be released one by one or multiple TRPs can be released at once. For example, by releasing multiple TRPs at once, TRP release can be performed quickly.

[0357] When releasing a connection TRP, the aforementioned TRP release indication can be used. The gNB can notify the UE of the TRP release indication. The UE can use this indication to release the connection target TRP.

[0358] The gNB can notify the UE of a TRP release instruction via the release target TRP. There can be one or more TRPs. These TRPs can be all or some of the release target TRPs. The UE determines the TRP sending the instruction as the release target TRP. Therefore, for example, the amount of information contained in the TRP release instruction sent from the gNB to the UE can be reduced. The UE can choose not to transmit or receive data with that TRP after receiving the instruction. Therefore, for example, erroneous actions such as using the TRP for data transmission or reception after the TRP has been released can be prevented.

[0359] As another example, the gNB can notify the UE of a TRP release indication via a TRP that is not the target of the release. This TRP could, for example, be the TRP with the best communication quality with the UE. Upon receiving this signal, the UE can release the connection with the TRP indicated by the release indication. This, for example, ensures the reliability of the release indication notification.

[0360] The UE can use this release instruction to stop its own beam used for communication with the released target TRP. The UE can stop uplink transmission and downlink reception of the released target TRP. For example, the UE can stop SRS transmission, stop PDCCH reception from that TRP, stop SS module reception from that TRP, or perform a combination of two or more of these actions. This, for example, can reduce power consumption in the UE.

[0361] Figure 22 This is a diagram illustrating the release action of the connection TRP in the UE. Figure 22 The example shown illustrates the scenario where the connection to TRP#2 is released to a UE connected to both TRP#1 and TRP#2. Additionally, Figure 22 This example illustrates how the UE measures the CSI-RS, and the gNB uses this measurement result to determine the action to release the target TRP for the connection. Additionally, Figure 22 This demonstrates how the gNB uses a different TRP than the one being released to notify the UE of the connection TRP release. Figure 22 In the middle, to and Figure 14 , Figure 15 , Figure 16 as well as Figure 17 Common parts are labeled with the same number, and the common description is omitted.

[0362] Figure 22 Steps ST1401, ST1402 and Figure 14 Same. Steps ST1501, ST1502 and... Figure 16 same.

[0363] Figure 22 Steps ST1405 to ST1416 and Figure 14 same.

[0364] exist Figure 22 In step ST1801, the gNB uses the measurement results from step ST1416 to determine TRP#2 in the connection target TRP of the UE.

[0365] exist Figure 22 In steps ST1805 and ST1806, the gNB notifies the UE of the instruction to release TRP#2 via TRP#1. Step ST1805 shows this instruction from the gNB to TRP#1, and step ST1806 shows this instruction from TRP#1 to the UE. This instruction can be transmitted using PDCCH. The UE uses step ST1806 to... Figure 22 In step ST1802 shown, the connection with TRP#2 is released.

[0366] Figure 22 Steps ST1511, ST1512 and Figure 17 same.

[0367] Figure 22 An example of CSI-RS measurement is shown, but it can also be used with... Figure 14 and Figure 15 The SS module is measured in the same way as the record. Thus, for example, the UE can directly use the signal used for TRP synchronization of the measurement object as the measurement object, so it can be measured quickly in the UE.

[0368] exist Figure 22 In the example shown in steps ST1805 and ST1806, the release of TRP#2 is illustrated via TRP#1, but it can also be done via TRP#2. Thus, for example, the gNB and UE can send and receive data to each other using the resources of TRP#1, which improves the efficiency of the communication system.

[0369] The method disclosed in Embodiment 1 can be used for the initial access of a UE. For example, the UE can establish connections with multiple TRPs during the initial access to the gNB. This, for example, improves the reliability of the connection process between the UE and the gNB.

[0370] As another example, the method disclosed in Implementation 1 can be used for cell reselection. For example, the method can be applied to the handover of the connection target TRP when the UE is in the RRC_INACTIVVE state. Paging of the UE from the gNB can be performed using all TRPs under the gNB, or it can be performed from a subset of the TRPs. The TRP used for paging the UE from the gNB can be one or more. Thus, for example, if the UE moves to the coverage area of ​​another TRP under the same gNB while in the RRC_INACTIVVE state, the gNB can also perform paging of the UE.

[0371] As another example, the method disclosed in Embodiment 1 can be used for handover. For example, the handover instruction from the gNB to the UE can include information related to the connection target TRP of the handover target base station. The UE can use this information to connect to the TRP. Thus, for example, the reliability of communication after handover can be improved.

[0372] As another example, the method disclosed in Embodiment 1 can be used for beam failure recovery. The gNB can notify the UE of the TRP and / or beam-related information related to reconnection. This information can, for example, be included in the beam failure recovery notification from the gNB to the UE. Thus, beam failure recovery in the UE can be performed quickly, for example.

[0373] Different primary TRPs and / or secondary TRPs can be used for each cell. This allows for flexible configuration of the primary and / or secondary TRPs based on factors such as the usage frequency of each cell, thereby improving the reliability of communication in the communication system. Different primary PDCCHs and / or secondary PDCCHs can also be used for each cell.

[0374] As another example, different primary TRPs and / or secondary TRPs can be used for each network slice. The primary and / or secondary TRPs can be determined using QCI. Thus, for example, the primary and / or secondary TRPs can be flexibly set according to the communication conditions of each network handover, resulting in improved communication reliability in the communication system. Different primary PDCCHs and / or secondary PDCCHs can also be used for each network slice.

[0375] Information related to the TRPs that can be connected to the UE (e.g., a list of TRP identifiers) can be pre-broadcast or notified to the UE from the gNB. As another example, information related to the TRP handover conditions in the UE (e.g., parameters and thresholds for determining TRP handover to the UE) can be pre-broadcast or notified to the UE from the gNB. The UE can use this information to perform TRP handover. This, for example, improves the flexibility of the communication system.

[0376] According to Embodiment 1, synchronization establishment during movement between TRPs can be performed quickly. Furthermore, synchronization establishment during movement between TRPs that are not synchronized with each other, such as those in networks with backhaul delays, can also be performed quickly.

[0377] Variation 1 of Implementation Method 1.

[0378] In Implementation 1, the switching, addition, and deletion of TRPs used for uplink and downlink communication are disclosed, but it is also possible to switch TRPs only for downlink communication.

[0379] The gNB can notify the UE of a downlink synchronization indication. This notification can be performed using a pre-handover TRP. The downlink synchronization indication can be delivered using, for example, L1 / L2 signaling. Thus, for example, the base station can quickly notify the UE of the downlink synchronization indication. As another example, the downlink synchronization indication can be delivered using MAC signaling or RRC signaling. Thus, for example, a large amount of information can be included in the downlink synchronization indication to notify the UE.

[0380] The information contained in the downlink synchronization indication from the gNB to the UE can be the same as (1) to (14) disclosed as examples of the information contained in the random access start indication in Implementation 1.

[0381] The UE can use the downlink synchronization indication to establish downlink synchronization with the TRP included in the downlink synchronization indication. The UE may choose not to transmit uplink signals and / or uplink data to this TRP. Uplink communication from the UE can continue to use the TRP used before the handover of the downlink communication TRP. Thus, for example, the UE can use different TRPs for uplink and downlink communication respectively. As a result, for example, even when the uplink and downlink radio wave environments differ, the most appropriate communication path can be used for uplink and downlink communication respectively.

[0382] The UE can maintain downlink synchronization with the TRP used for uplink communication. Thus, for example, the UE can maintain uplink synchronization with the TRP, which results in improved reliability in uplink communication.

[0383] The UE can send an SR to the TRP before the handover. The information required for sending the SR to the TRP before the handover, such as information related to the PUCCH resource settings used for the SR, can be information used before receiving the downlink synchronization indication.

[0384] The gNB can send the uplink grant for the SR to the UE via the downlink communication TRP after the handover. The settings required by the UE when receiving the uplink grant, such as settings related to the mapping of DCI sent from the downlink communication TRP after the handover (e.g., search space settings in the PDCCH), can be notified to the UE in advance from the gNB or included in the downlink synchronization indication. Thus, for example, the UE can receive the grant sooner than with the downlink communication TRP after the handover. As a result, for example, the communication quality between the UE and the gNB can be ensured even in cases where the downlink communication environment with the previous downlink communication TRP deteriorates drastically.

[0385] The UE can use this uplink permission to notify that downlink synchronization has been established with the TRP. In this communication, the downlink communication TRP after the handover can be used. Therefore, for example, it is possible to prevent the gNB from using the handover TRP to send downlink data before downlink synchronization is complete, thus avoiding the reduction in communication efficiency caused by the downlink data not being delivered.

[0386] This information notification can, for example, use L1 / L2 signaling. Thus, for example, the UE can quickly notify that downlink synchronization has been established. As other examples, MAC signaling or RRC signaling can be used. Thus, for example, the UE can transmit a large amount of information and notify the gNB.

[0387] As another example, notification of the establishment of downlink synchronization can use PRACH. For example, the UE can send PRACH to the TRP after the handover. The gNB may not send an RA response to the PRACH to the UE. The UE may not receive an RA response to the PRACH. The UE can obtain the PRACH transmission timing through broadcast information from the gNB, or through the downlink synchronization indication mentioned above. In the case of obtaining the PRACH transmission timing from the downlink synchronization indication, (6) disclosed as an example of information included in the random access start indication from the gNB to the UE can be used.

[0388] This information may include information related to the TRP (Transfer Reference Point) for which downlink synchronization has been established. The gNB can use this information to begin transmitting downlink data using that TRP. This, for example, prevents the gNB from using the post-handover TRP to transmit downlink data before downlink synchronization is complete, thus avoiding the reduction in communication efficiency caused by the downlink data not being delivered. The information may contain multiple TRPs. This, for example, reduces the signaling load from the UE to the base station.

[0389] As another example, this information may not include information related to TRPs with established downlink synchronization. This information could be configured such that omitting information related to TRPs with established downlink synchronization indicates that downlink synchronization with all TRPs after the handover has been completed in the UE. This, for example, can reduce the signaling volume from the UE to the base station.

[0390] The UE can send this information to the gNB via the pre-handover TRP. This pre-handover TRP could, for example, be an uplink transmission TRP. Thus, for example, when the uplink and downlink radio environments differ, the most appropriate communication path can be used for uplink and downlink communication respectively. This results in improved reliability in information transmission.

[0391] The timing of the HARQ response for downlink data in the UE can be derived from the slot number of the uplink communication TRP at the downlink data reception time as a reference. The slot offset from downlink data reception to HARQ response transmission can be a slot offset in units of the slot length in the uplink communication TRP. This slot offset can be statically notified to the UE by the gNB, dynamically notified, or a combination of both. For example, the UE can transmit the HARQ response using the slot number obtained by adding this slot offset to the slot number of the uplink communication TRP at the downlink data reception time. The gNB can use the TA in each TRP and / or the difference between the backhaul delay and the backhaul delay of each TRP to derive the slot number of the uplink communication TRP at the downlink data reception time in the UE. Thus, for example, the UE can also transmit the HARQ response to a TRP that is asynchronous with the downlink communication TRP.

[0392] Even in the SRS transmission timing within the UE, the same method as for the HARQ response timing for downlink data can be used. Thus, for example, the same effect as described above can be achieved.

[0393] The UE may choose not to switch downlink communication TRPs. For example, if the downlink communication TRP handover from the gNB fails, the UE may choose not to switch downlink communication TRPs. In the above scenario, the UE can notify the gNB of the downlink communication TRP handover failure. In this scenario, the previous TRP can be used in downlink communication between the gNB and the UE. Therefore, for example, even if the downlink communication TRP handover fails, communication between the UE and the gNB can continue.

[0394] Figure 23 and Figure 24 This is a diagram illustrating the actions of the TRP used for downlink communication during UE switching. Figure 23 and Figure 24 Connect at the boundary line BL2324. Figure 23 and Figure 24 This illustrates a scenario where, for a UE connected to TRP#1, the downlink communication TRP is switched to TRP#2, and TRP#1 becomes the uplink communication TRP. Additionally, Figure 23 and Figure 24This illustrates an example of a situation where the UE measures the CSI-RS, and the gNB uses this measurement result to determine the action to switch downlink communication using the TRP. Figure 23 and Figure 24 In the middle, to and Figure 14 and Figure 15 Common parts are labeled with the same number, and the common description is omitted.

[0395] Figure 23 Steps ST1401 to ST1416 in the middle Figure 14 same.

[0396] exist Figure 23 In step ST2501, the gNB uses the measurement results from step ST1416 to determine whether to switch the UE's downlink communication TRP from TRP#1 to TRP#2.

[0397] exist Figure 23 In steps ST2505 and ST2503, the gNB instructs the UE to initiate a downlink communication TRP handover via TRP#1. Step ST2502 shows this instruction from the gNB to TRP#1, and step ST2503 shows this instruction from TRP#1 to the UE. This instruction can be transmitted using the PDCCH. The instruction contains information indicating a handover from TRP#1 to TRP#2 for downlink communication. The UE uses step ST2503 to... Figure 24 The step ST1428 shown indicates the start of the SS module reception operation from TRP#2 to the UE. Figure 24 In step ST1429, the UE uses the SS module from step ST1428 to establish downlink synchronization with TRP#2.

[0398] exist Figure 24 In steps ST2504 and ST2505, the UE notifies the gNB via TRP#1 that downlink synchronization with TRP#2 has been completed. Step ST2504 shows this notification from the UE to TRP#1, and step ST2505 shows this notification from TRP#1 to the gNB. The gNB uses ST2505 to identify the completion of the handover of the downlink communication TRP in the UE.

[0399] exist Figure 24 In steps ST2507 and ST2508, the UE transmits uplink data to the gNB via TRP#1. Step ST2507 shows the data transmission from the UE to TRP#1, and step ST2508 shows the data transmission from TRP#1 to the gNB.

[0400] exist Figure 24In steps ST2509 and ST2510, downlink data is transmitted from the gNB to the UE via TRP#2. Step ST2509 shows the data transmission from the gNB to TRP#2, and step ST2510 shows the data transmission from TRP#2 to the UE.

[0401] Figure 23 and Figure 24 An example of CSI-RS measurement is shown, but it can also be used with... Figure 14 and Figure 15 The SS module is measured in the same way as the record. Thus, for example, the UE can directly use the signal used for TRP synchronization of the measurement object as the measurement object, so it can be measured quickly in the UE.

[0402] Figure 25 and Figure 26 This is a diagram illustrating other examples of TRP actions used for downlink communication in a switching UE. Figure 25 and Figure 26 Connect at the boundary line BL2526. Figure 25 and Figure 26 The example shown illustrates a scenario where a UE communicating uplink with TRP#1 and downlink with TRP#2 switches its downlink communication TRP from TRP#2 to TRP#3. Additionally, Figure 25 and Figure 26 This illustrates an example of a situation where the UE measures the CSI-RS, and the gNB uses this measurement result to determine the action to switch downlink communication using the TRP. Figure 25 and Figure 26 In the middle, to and Figure 14 and Figure 15 Common parts are labeled with the same number, and the common description is omitted.

[0403] exist Figure 25 In steps ST2601 and ST2602, the UE transmits uplink data to the gNB via TRP#1. Step ST2601 shows the data transmission from the UE to TRP#1, and step ST2602 shows the data transmission from TRP#1 to the gNB.

[0404] exist Figure 25 In steps ST2603 and ST2604, downlink data is transmitted from the gNB to the UE via TRP#2. Step ST2603 shows the data transmission from the gNB to TRP#2, and step ST2604 shows the data transmission from TRP#2 to the UE.

[0405] Figure 25 Steps ST1405 to ST1411 and Figure 14same. Figure 25 Step ST1503 and Figure 16 same. Figure 25 Steps ST1413 to ST1416 and Figure 14 same.

[0406] exist Figure 25 In step ST2611, the gNB uses the measurement results from step ST1416 to determine whether to switch the UE's downlink communication TRP from TRP#2 to TRP#3.

[0407] exist Figure 25 In steps ST2605 and ST2606, the gNB instructs the UE to initiate a downlink communication TRP handover via TRP#2. Step ST2605 shows this instruction from the gNB to TRP#2, and step ST2606 shows this instruction from TRP#2 to the UE. This instruction can be transmitted using the PDCCH. The instruction contains information indicating a handover from TRP#2 to TRP#3 for downlink communication. The UE uses step ST2606 to... Figure 26 The step ST1528 shown indicates the start of the SS module reception operation from TRP#3 to the UE. Figure 26 In step ST1529, the UE uses the SS module from step ST1528 to establish downlink synchronization with TRP#3.

[0408] Figure 26 The steps ST2504, ST2505 and shown are Figure 24 same.

[0409] Figure 26 The steps ST2507, ST2508 and shown are Figure 24 same.

[0410] exist Figure 26 In steps ST2609 and ST2610, downlink data is transmitted from the gNB to the UE via TRP#3. Step ST2609 shows the data transmission from the gNB to TRP#3, and step ST2610 shows the data transmission from TRP#3 to the UE.

[0411] Figure 25 and Figure 26 An example of CSI-RS measurement is shown, but it can also be used with... Figure 14 and Figure 15 The SS module is measured in the same way as the record. Thus, for example, the UE can directly use the signal used for TRP synchronization of the measurement object as the measurement object, so it can be measured quickly in the UE.

[0412] This variation 1 of implementation method 1 can be applied to situations where the uplink communication TRP and the downlink communication TRP become the same after a downlink communication TRP handover. In this case, the UE can use the downlink TRP handover indication to maintain the downlink synchronization state required for continuous uplink communication. The UE does not need to notify the gNB of downlink synchronization completion. Thus, for example, a rapid downlink communication TRP handover can be performed in the UE.

[0413] Figure 27 and Figure 28 This is a diagram illustrating other examples of TRP actions used for downlink communication in a switching UE. Figure 27 and Figure 28 Connect at the boundary line BL2728. Figure 27 and Figure 28 The example shown illustrates a UE that communicates uplink with TRP#1 and downlink with TRP#2, where the downlink communication TRP is switched from TRP#2 to TRP#1, and both uplink and downlink communication are conducted with TRP#1. Additionally, Figure 27 and Figure 28 This illustrates an example of a situation where the UE measures the CSI-RS, and the gNB uses this measurement result to determine the action to switch downlink communication using the TRP. Figure 27 and Figure 28 In the middle, to and Figure 14 , Figure 15 , Figure 25 as well as Figure 26 Common parts are labeled with the same number, and the common description is omitted.

[0414] Figure 27 Steps ST2601 to ST2604 in the middle Figure 25 same.

[0415] Figure 27 Steps ST1405 to ST1416 and Figure 14 same.

[0416] exist Figure 27 In step ST2701, the gNB uses the measurement results from step ST1416 to determine whether to switch the UE's downlink communication TRP from TRP#2 to TRP#1.

[0417] exist Figure 27In steps ST2705 and ST2706, the gNB instructs the UE to initiate a downlink communication TRP handover via TRP#2. Step ST2705 shows this instruction from the gNB to TRP#2, and step ST2706 shows this instruction from TRP#2 to the UE. This instruction can be transmitted using the PDCCH. The instruction contains information indicating a handover from TRP#2 to TRP#1 for downlink communication. The UE uses step ST2706 to... Figure 28 The step ST2702 shown indicates the start of the SS module reception operation from TRP#1 to the UE. Figure 28 In step ST2703, the UE uses the SS module from step ST2702 to establish downlink synchronization with TRP#1.

[0418] Figure 28 The steps ST2504, ST2505 and shown are Figure 24 same.

[0419] Figure 28 The steps ST1511, ST1512 and shown are Figure 17 same.

[0420] Figure 27 and Figure 28 An example of CSI-RS measurement is shown, but it can also be used with... Figure 14 and Figure 15 The SS module is measured in the same way as the record. Thus, for example, the UE can directly use the signal used for TRP synchronization of the measurement object as the measurement object, so it can be measured quickly in the UE.

[0421] exist Figure 27 and Figure 28 The diagram illustrates an example of the UE establishing downlink synchronization with TRP#1 in step ST2703, but downlink synchronization can also be omitted. In this case, the UE can maintain the downlink synchronization state required for continuous uplink communication. In this case, the UE can omit the downlink synchronization completion notification in steps ST2504 and ST2505. Therefore, for example, rapid downlink communication TRP handover can be performed within the UE.

[0422] According to Embodiment 1 of Implementation Method 1, the UE can use different TRPs for uplink and downlink communication respectively. As a result, for example, when the radio wave environments of the uplink and downlink are different, the most appropriate communication path can be used for uplink and downlink communication respectively.

[0423] Variation 2 of Implementation Method 1.

[0424] In a variation of implementation 1, TRP is switched only for downlink communication, but it is also possible to switch TRP only for uplink communication.

[0425] The gNB can notify the UE of an uplink synchronization indication. This notification can be performed using a pre-handover TRP. The uplink synchronization indication can be the random access start indication disclosed in Implementation 1, or other signaling. For example, the uplink synchronization indication can be performed using L1 / L2 signaling. Thus, for example, the base station can quickly notify the UE of the uplink synchronization indication. As another example, the uplink synchronization indication can be performed using MAC signaling or RRC signaling. Thus, for example, a large amount of information can be included in the uplink synchronization indication to notify the UE.

[0426] The random access start indication includes information indicating that only the uplink communication TRP is being switched. For example, an identifier indicating that only the uplink communication TRP is being switched can be included in the random access start indication. Alternatively, it can also include information indicating that the downlink communication TRP is not being switched. For example, it can include an identifier indicating that the downlink communication TRP is not being switched, or it can include information about the original TRP (e.g., the identifier of the original TRP) as the downlink communication TRP. Thus, for example, no new signaling needs to be set as the uplink synchronization indication, resulting in avoiding design complexity in the communication system.

[0427] The UE can notify the uplink communication TRP prior to the handover of the HARQ response to the uplink synchronization indication. Thus, for example, even if the HARQ decoding result of the uplink synchronization indication in the UE is NG, the UE can still notify the gNB of HARQ-Nack.

[0428] The information contained in the uplink synchronization indication from the gNB to the UE can be the same as (1) to (14) disclosed as examples of the information contained in the random access start indication in Implementation 1.

[0429] The UE can use the uplink synchronization indication to establish uplink synchronization with the TRP included in the uplink synchronization indication. The uplink synchronization establishment process can, for example, be a random access process. In downlink communication, the UE can continue to use the TRP used before the handover of the uplink communication TRP. Thus, for example, the UE can use different TRPs for uplink and downlink communication. As a result, for example, even when the uplink and downlink radio wave environments are different, the most appropriate communication path can be used for uplink and downlink communication respectively.

[0430] The gNB can notify the UE of information indicating that uplink synchronization has been established with the TRP. This notification can, for example, be a random access response from the gNB to the UE. Thus, for example, no new signaling needs to be set up for uplink synchronization establishment processing and uplink synchronization establishment notification. The result is the avoidance of design complexity in the communication system.

[0431] The timing of the HARQ response for downlink data in the UE can be derived from the slot number of the uplink communication TRP at the downlink data reception time as a reference. The slot offset from downlink data reception to HARQ response transmission can be a slot offset in units of the slot length in the uplink communication TRP. This slot offset can be statically notified to the UE by the gNB, dynamically notified, or a combination of both. For example, the UE can transmit the HARQ response using the slot number obtained by adding this slot offset to the slot number of the uplink communication TRP at the downlink data reception time. The gNB can use the TA in each TRP and / or the difference between the backhaul delay and the backhaul delay of each TRP to derive the slot number of the uplink communication TRP at the downlink data reception time in the UE. Thus, for example, the UE can also transmit the HARQ response to a TRP that is asynchronous with the downlink communication TRP.

[0432] Even in the SRS transmission timing within the UE, the same method as for the HARQ response timing for downlink data can be used. Thus, for example, the same effect as described above can be achieved.

[0433] Figure 29 and Figure 30 This is a diagram illustrating the actions of the TRP used for uplink communication in the UE during switching. Figure 29 and Figure 30 Connect at the boundary line BL2930. Figure 29 and Figure 30 The example shown illustrates a scenario where, for a UE connected to TRP#1, the downlink communication TRP is switched to TRP#2, and TRP#1 becomes the downlink communication TRP. Additionally, Figure 29 and Figure 30 This illustrates an example of a situation where the UE measures the CSI-RS, and the gNB uses this measurement result to determine the action to switch uplink communication using the TRP. Figure 29 and Figure 30 In the middle, to and Figure 14 and Figure 15 Common parts are labeled with the same number, and the common description is omitted.

[0434] Figure 29 Steps ST1401 to ST1416 in the middle Figure 14 same.

[0435] exist Figure 29 In step ST3100, the gNB uses the measurement results from step ST1416 to determine whether to switch the UE's uplink communication TRP from TRP#1 to TRP#2.

[0436] exist Figure 29 In steps ST3101 and ST3102, the gNB instructs the UE to initiate a handover of the uplink communication TRP via TRP#1. Step ST3101 shows this instruction from the gNB to TRP#1, and step ST3102 shows this instruction from TRP#1 to the UE. This instruction can be transmitted using the PDCCH. The instruction contains information indicating a handover from TRP#1 to TRP#2 for uplink communication. The instruction may include information related to the RA preamble. The UE uses step ST3102 to... Figure 30 The step ST1428 shown indicates the start of the SS module reception operation from TRP#2 to the UE. Figure 30 In step ST1429, the UE uses the SS module from step ST1428 to establish downlink synchronization with TRP#2.

[0437] exist Figure 30 In steps ST3103 and ST3104, the UE transmits a PRACH to the gNB via TRP#2. Step ST3103 shows the PRACH transmission from the UE to TRP#2, and step ST3104 shows the PRACH transmission from TRP#2 to the gNB. The RA preamble in this PRACH transmission can be the same as the RA preamble included in step ST3102, or it can be different.

[0438] exist Figure 30 In steps ST3105 and ST3106, the gNB notifies the UE of the random access response via TRP#1. Step ST3105 shows the random access response notification from the gNB to TRP#1, and step ST3106 shows the random access response notification from TRP#1 to the UE. The UE uses this response to establish uplink synchronization with TRP#2.

[0439] exist Figure 30 In steps ST3107 and ST3108, the UE transmits uplink data to the gNB via TRP#2. Step ST3107 shows the data transmission from the UE to TRP#2, and step ST3108 shows the data transmission from TRP#2 to the gNB.

[0440] exist Figure 30In steps ST3109 and ST3110, downlink data is transmitted from the gNB to the UE via TRP#1. Step ST3109 shows the data transmission from the gNB to TRP#1, and step ST3110 shows the data transmission from TRP#1 to the UE.

[0441] Figure 29 and Figure 30 An example of CSI-RS measurement is shown, but it can also be used with... Figure 14 and Figure 15 The SS module is measured in the same way as the record. Thus, for example, the UE can directly use the signal used for TRP synchronization of the measurement object as the measurement object, so it can be measured quickly in the UE.

[0442] exist Figure 29 and Figure 30 The image shows an example of a UE establishing uplink synchronization after a random access response, but it can also be done with... Figure 14 and Figure 15 Similarly, the UE sends a random access message 3 to the gNB. The gNB can send a random access message 4 to the UE. Thus, for example, contention-based random access can be performed during TRP handover between the UE and the gNB, resulting in an increase in the number of UEs that can be accommodated in the gNB.

[0443] Figure 31 and Figure 32 This is a diagram illustrating another example of the actions of TRP in switching uplink communication in a UE. Figure 31 and Figure 32 Connect at the boundary line BL3132. Figure 31 and Figure 32 The example shown illustrates a scenario where a UE communicating downlink with TRP#1 and uplink with TRP#2 switches its uplink communication TRP from TRP#2 to TRP#3. Additionally, Figure 31 and Figure 32 This illustrates an example of a situation where the UE measures the CSI-RS, and the gNB uses this measurement result to determine the action to switch uplink communication using the TRP. Figure 31 and Figure 32 In the middle, to and Figure 14 , Figure 15 , Figure 16 , Figure 17 , Figure 29 as well as Figure 30 Common parts are labeled with the same number, and the common description is omitted.

[0444] Figure 31 The steps ST3201, ST3202 and shown are Figure 30Steps ST3107 and ST3108 are the same. Steps ST3203 and ST3204 are the same. Figure 30 The steps shown in ST3109 and ST3110 are the same.

[0445] Figure 31 The steps ST1405 to ST1411 shown are... Figure 14 same. Figure 31 The steps shown in ST1503 and Figure 16 same. Figure 31 The steps ST1413 shown are... Figure 14 same.

[0446] exist Figure 31 In steps ST3205 and ST3206, the UE notifies the gNB of the CSI-RS measurement results via TRP#2. The information contained in steps ST3205 and ST3206 can be compared with... Figure 14 The steps ST1415 and ST1416 shown are the same. The signaling used in steps ST3205 and ST3206 can be the same as... Figure 14 The steps ST1415 and ST1416 shown are the same.

[0447] exist Figure 31 In step ST3200, the gNB uses the measurement results from step ST3206 to determine whether to switch the UE's uplink communication TRP from TRP#2 to TRP#3.

[0448] exist Figure 31 In steps ST3211 and ST3212, the gNB instructs the UE to initiate a handover of the uplink communication TRP via TRP#1. Step ST3211 shows this instruction from the gNB to TRP#1, and step ST3212 shows this instruction from TRP#1 to the UE. This instruction can be transmitted using the PDCCH. The instruction contains information indicating a handover from TRP#2 to TRP#3 for uplink communication. The instruction may contain information related to the RA preamble. The UE uses step ST3212 to... Figure 32 The step ST1528 shown indicates the start of the SS module reception operation from TRP#3 to the UE. Figure 32 In step ST1529, the UE uses the SS module from step ST1528 to establish downlink synchronization with TRP#3.

[0449] exist Figure 32In steps ST3207 and ST3208, the UE transmits a PRACH to the gNB via TRP#3. Step ST3207 shows the PRACH transmission from the UE to TRP#3, and step ST3208 shows the PRACH transmission from TRP#3 to the gNB. The RA preamble in this PRACH transmission can be the same as the RA preamble included in step ST3212, or it can be different.

[0450] Figure 32 The steps ST3105 and ST3106 shown are related to Figure 30 The same random access response. The UE uses this response to establish uplink synchronization with TRP#3.

[0451] exist Figure 32 In steps ST3209 and ST3210, the UE transmits uplink data to the gNB via TRP#3. Step ST3209 shows the data transmission from the UE to TRP#3, and step ST3210 shows the data transmission from TRP#3 to the gNB.

[0452] Figure 32 The steps ST3109, ST3110 and shown are Figure 30 same.

[0453] Figure 31 and Figure 32 An example of CSI-RS measurement is shown, but it can also be used with... Figure 14 and Figure 15 The SS module is measured in the same way as the record. Thus, for example, the UE can directly use the signal used for TRP synchronization of the measurement object as the measurement object, so it can be measured quickly in the UE.

[0454] exist Figure 31 and Figure 32 The image shows an example of a UE establishing uplink synchronization after a random access response, but it can also be done with... Figure 14 and Figure 15 Similarly, the UE sends a random access message 3 to the gNB. The gNB can send a random access message 4 to the UE. Thus, for example, contention-based random access can be performed during TRP handover between the UE and the gNB, resulting in an increase in the number of UEs that can be accommodated in the gNB.

[0455] This variation 2 of implementation method 1 can be applied to situations where the uplink communication TRP and the downlink communication TRP become the same after the uplink communication TRP is switched. In this case, the UE can use the uplink TRP switching indication to maintain the downlink synchronization state required for continuous downlink communication. Thus, for example, a rapid uplink communication TRP switch can be performed in the UE.

[0456] Figure 33 and Figure 34 This is a diagram illustrating another example of the actions of TRP in switching uplink communication in a UE. Figure 33 and Figure 34 Connect at the boundary line BL3334. Figure 33 and Figure 34 The example shown illustrates a UE that communicates downlink with TRP#1 and uplink with TRP#2, where the downlink communication TRP is switched from TRP#2 to TRP#1, and both uplink and downlink communication are conducted with TRP#1. Additionally, Figure 33 and Figure 34 This illustrates an example of a situation where the UE measures the CSI-RS, and the gNB uses this measurement result to determine the action to switch uplink communication using the TRP. Figure 33 and Figure 34 In the middle, to and Figure 14 , Figure 15 , Figure 17 , Figure 18 , Figures 29-32 Common parts are labeled with the same number, and the common description is omitted.

[0457] Figure 33 The steps ST3201 to ST3204 shown are... Figure 31 same.

[0458] Figure 33 The steps ST1405 to ST1413 shown are... Figure 14 same. Figure 33 The steps ST3205, ST3206 and shown are Figure 31 same.

[0459] exist Figure 33 In step ST3300, the gNB uses the measurement results from step ST3206 to determine whether to switch the UE's uplink communication TRP from TRP#2 to TRP#1.

[0460] exist Figure 33In steps ST3101 and ST3102, the gNB instructs the UE to initiate a handover of the uplink communication TRP via TRP#1. Step ST3101 shows this instruction from the gNB to TRP#1, and step ST3102 shows this instruction from TRP#1 to the UE. This instruction can be transmitted using the PDCCH. The instruction contains information indicating a handover from TRP#2 to TRP#1 for uplink communication. The instruction may contain information related to the RA preamble. The UE uses step ST3102 to... Figure 34 The step ST2702 shown indicates the start of the SS module reception operation from TRP#1 to the UE. Figure 34 In step ST2506, the UE uses the SS module of step ST2702 to establish downlink synchronization with TRP#1.

[0461] exist Figure 34 In steps ST3301 and ST3302, the UE transmits a PRACH to the gNB via TRP#1. Step ST3301 shows the PRACH transmission from the UE to TRP#1, and step ST3302 shows the PRACH transmission from TRP#1 to the gNB. The RA preamble in this PRACH transmission can be the same as the RA preamble included in step ST3102, or it can be different.

[0462] Figure 34 The steps ST3105 and ST3106 shown are related to Figure 30 The same random access response. The UE uses this response to establish uplink synchronization with TRP#1.

[0463] Figure 34 The steps ST1511, ST1512 and shown are Figure 17 same.

[0464] Figure 33 and Figure 34 An example of CSI-RS measurement is shown, but it can also be used with... Figure 14 and Figure 15 The SS module is measured in the same way as the record. Thus, for example, the UE can directly use the signal used for TRP synchronization of the measurement object as the measurement object, so it can be measured quickly in the UE.

[0465] exist Figure 33 and Figure 34 The image shows an example of a UE establishing uplink synchronization after a random access response, but it can also be done with... Figure 14 and Figure 15Similarly, the UE sends a random access message 3 to the gNB. The gNB can send a random access message 4 to the UE. Thus, for example, contention-based random access can be performed during TRP handover between the UE and the gNB, resulting in an increase in the number of UEs that can be accommodated in the gNB.

[0466] exist Figure 33 and Figure 34 The diagram illustrates an example of the UE establishing downlink synchronization with TRP#1 in step ST2506, but downlink synchronization can also be omitted. In the above example, the UE can maintain the downlink synchronization state during ongoing downlink communication. Therefore, for example, rapid downlink communication TRP handover can be performed within the UE.

[0467] The TRP switching disclosed in Embodiment 1 can be performed through a combination of Modification 1 and Modification 2 of Embodiment 1. That is, the TRP switching can be divided into switching of the uplink communication TRP and switching of the downlink communication TRP. In the above, the uplink communication TRP can be switched first. For example, when switching from a TRP capable of high-power transmission (hereinafter, sometimes referred to as a high-power TRP) to a TRP capable of low-power transmission (hereinafter, sometimes referred to as a low-power TRP), the uplink communication TRP can be switched to a low-power TRP first as the distance between the UE and the high-power TRP increases. For example, if the distance between the UE and the high-power TRP further increases, the downlink communication TRP can be switched to a low-power TRP. Thus, for example, communication quality can be ensured in both the uplink and downlink.

[0468] As another example, the downlink communication TRP can be switched first. For instance, when switching from a low-power TRP to a high-power TRP, the downlink communication TRP can be switched to the high-power TRP first, for example, by bringing the UE closer to the high-power TRP. Then, if the distance between the UE and the high-power TRP further decreases, the uplink communication TRP can be switched to the high-power TRP. This achieves the same effect as described above.

[0469] In this variation 2 of Embodiment 1, an uplink communication TRP can be added, or an uplink communication TRP can be released. The method disclosed in Embodiment 1 can be applied in the addition and / or release of the uplink communication TRP. This, for example, improves the flexibility of the communication system.

[0470] According to this embodiment 2 of implementation method 1, the UE can use different TRPs for uplink and downlink communication respectively. As a result, for example, when the radio wave environments of the uplink and downlink are different, the most appropriate communication path can be used for uplink and downlink communication respectively.

[0471] Variation 3 of Implementation Method 1.

[0472] When multiple TRPs are added simultaneously, the following problems arise. Specifically, if the UE sends a PRACH to some of the added TRPs, the RA preamble interferes with the TRPs of other added TRPs, resulting in degraded PRACH communication quality. Additionally, other added TRPs may falsely detect the aforementioned RA preamble.

[0473] A solution to the aforementioned problem is disclosed. Different RA preambles are assigned to the PRACH for each TRP. The gNB can assign multiple RA preambles to the UE. The gNB can notify the UE of information obtained by combining the TRP and / or beam with the assigned RA preambles. The UE can use this information to send the RA preambles contained in the information to the TRPs and / or beams contained in the information. Among the TRPs and / or beams contained in the information sent to the UE, the gNB can receive only the RA preambles contained in the information. Thus, for example, false detection of RA preambles for other TRPs can be prevented by the TRPs.

[0474] This information may be included, for example, in the random access indication disclosed in Embodiment 1 for notification, or in the uplink synchronization indication disclosed in Variation 2 of Embodiment 1 for notification.

[0475] Other solutions are disclosed. The transmission timing of PRACH for each TRP is made different from each other. The gNB can assign multiple PRACH transmission timings to the UE. The gNB can notify the UE of information combining the TRP and / or beam with the PRACH transmission timing. The UE can use this information to transmit PRACH to the TRP and / or beam included in the information at the specified PRACH transmission timing. Among the TRPs and / or beams included in the information sent to the UE, the gNB can receive PRACH only at the specified PRACH transmission timing. Thus, for example, it is possible to prevent the PRACH communication quality degradation caused by interference between PRACH for a TRP and PRACH for other TRPs.

[0476] This information may be included, for example, in the random access indication disclosed in Embodiment 1 for notification, or in the uplink synchronization indication disclosed in Variation 2 of Embodiment 1 for notification.

[0477] The gNB can notify the UE only of information related to the TRP and / or beam. The UE can use the broadcast information from the gNB to obtain the PRACH transmission timing in that TRP and / or beam. Thus, for example, the signaling load from the gNB to the UE can be reduced.

[0478] The two solutions described above can be combined. For example, the RA preamble and PRACH transmission timing for each TRP can be made different from each other. This, for example, can further prevent the PRACH for a TRP from interfering with the PRACH for other TRPs, thus preventing a degradation in PRACH communication quality.

[0479] Other solutions are disclosed. The UE can avoid simultaneously adding multiple TRPs. For example, the UE can avoid sending PRACH to other TRPs before receiving an RA response from one TRP. This, for example, prevents degradation in PRACH communication quality due to interference with PRACH to other TRPs, and false detection of PRACH in other TRPs. Furthermore, it avoids the complexity of UE processing.

[0480] The gNB can also receive PRACH messages sent to a specific TRP within any TRP. The UE can also receive RA responses at any RA response reception time corresponding to the aforementioned TRPs. Therefore, for example, the RA connection opportunities within the UE can be expanded, resulting in rapid RA processing from the UE.

[0481] According to this variation 3 of embodiment 1, during the switching and / or addition of multiple TRPs, interference between PRACHs of each TRP can be reduced and false detections of PRACHs between TRPs can be prevented. As a result, the reliability of random access processing can be improved.

[0482] Variation 4 of Implementation Method 1.

[0483] The following problem can occur during TRP measurements performed by the UE: The UE cannot measure the target TRP if the connected TRP is out of sync with the target TRP.

[0484] A solution to the above problems is disclosed. The UE uses measurement intervals to measure each TRP. The UE can establish synchronization with the measured TRP during the measurement interval.

[0485] The TRPs and / or beams measured by the UE using the measurement gap can be TRPs and / or beams that are asynchronous with the currently connected TRPs and / or beams. The gNB can notify the UE of information related to TRPs and / or beams that are asynchronous with the currently connected TRPs and / or beams. This information can be, for example, the same as (1) disclosed as information included in the random access start indication from the gNB to the UE in Embodiment 1. The UE can use this information to obtain information about TRPs that are asynchronous with the currently connected TRPs and / or beams. The UE can perform the measurement of TRPs and / or beams that are synchronized with the currently connected TRPs and / or beams at a time different from the measurement gap. Thus, for example, it is possible to suppress the increase in the number of measurement target TRPs and / or beams in the measurement gap. In the above, synchronization means, for example, that the difference between the transmission delay (e.g., backhaul delay) from the gNB to each TRP is less than or equal to the time of the cyclic prefix.

[0486] As another example, the gNB can notify the UE of information related to the TRP and / or beam that is being synchronized with the connected TRP and / or beam. This information can be the same as described above. This information can also indicate whether a QCL (Quasi-CoLocated) relationship exists between each TRP and / or beam and the connected TRP and / or beam.

[0487] According to this variation 4 of embodiment 1, the UE can perform measurements of both the TRP and / or beam synchronized with the connected TRP and / or beam, and the TRP and / or beam asynchronous with the connected TRP and / or beam, within a short period of time. As a result, efficiency in the communication system can be reduced.

[0488] Variation 5 of Implementation Method 1.

[0489] The primary TRP can be switched without switching the TRP to which the UE is connected. The primary TRP can be the TRP the UE was connected to during initial access. As another example, the primary TRP is the TRP that can preferentially transmit control plane data compared to other TRPs. The primary TRP can be just one of the TRPs connected to the UE, or it can be multiple TRPs. The secondary TRP can be any TRP connected to the UE other than the primary TRP. In the above, the gNB can instruct the UE to switch the primary TRP. The UE can use this instruction to switch the primary TRP. The UE can use the switched primary TRP as the connection target TRP other than the primary TRP.

[0490] This instruction can be communicated using L1 / L2 signaling such as PDCCH. Thus, for example, the gNB can perform a rapid primary TRP handover to the UE.

[0491] As another example, this instruction can be communicated using MAC signaling. Thus, for example, it is possible to rapidly notify the UE from the gNB while simultaneously transmitting a large amount of information via multi-modulation.

[0492] As another example, this indication can be communicated using RRC signaling. Thus, for example, a significant amount of information can be further transmitted from the gNB to the UE.

[0493] As another example, this indication can be communicated using RRC signaling. Thus, for example, a significant amount of information can be further transmitted from the gNB to the UE.

[0494] As another example, this instruction can be notified as a combination of the above. For instance, the gNB can use RRC signaling to inform the UE in advance of information obtained by associating the candidate handover target TRP with a specified consecutive number, and use L1 / L2 signaling to inform the UE from the gNB of the aforementioned consecutive number corresponding to the handover target TRP. Thus, for example, a large amount of information can be sent from the gNB to the UE while a rapid TRP handover can be performed.

[0495] The information included in the handover indication of the primary TRP may be the same as the information disclosed in (1) as the random access start indication from gNB to UE in Implementation 1.

[0496] The handover of the TRP that transmits the primary and / or secondary PDCCHs can also be performed when there is no handover of the TRP to which the UE is connected. The primary PDCCH can be a PDCCH transmitted from the primary TRP. The secondary PDCCH can be a PDCCH other than the primary PDCCH. As another example, the primary PDCCH is the PDCCH that can be prioritized for scheduling control plane data compared to other PDCCHs. In the above, the gNB can indicate to the UE the handover of the TRP that transmits the primary and / or secondary PDCCHs. This indication can be notified using the same signaling as the handover indication of the primary TRP. The handover indication of the TRP that transmits the primary PDCCH and the handover indication of the TRP that transmits the secondary PDCCH can be given using the same signaling or different signaling. This, for example, improves scheduling flexibility.

[0497] There can be one or more TRPs sending the secondary PDCCH. There may be no TRPs sending the secondary PDCCH. In the absence of a TRP sending the secondary PDCCH, the secondary PDCCH can be invalidated. Each TRP may choose not to send either the primary or secondary PDCCH. As another example, each TRP may send both the primary and secondary PDCCH. This, for example, avoids the complexity of TRP control in the communication system.

[0498] The information included in the indication of the handover of the TRP for sending the primary and secondary PDCCHs can be the same information disclosed as (12) in the indication of the start of random access to the UE from the gNB in ​​Implementation 1.

[0499] The activation / deactivation of the secondary PDCCH can be performed without switching the TRP to which the UE is connected. The primary PDCCH can always be active. The gNB can indicate the activation / deactivation of the primary PDCCH to the UE. This indication can be sent using the same signaling as the primary TRP handover indication. The same signaling can be used for the handover indication of the TRP sending the primary PDCCH, and the handover indication of the TRP sending the secondary PDCCH, and different signaling can also be used. This, for example, improves scheduling flexibility.

[0500] The handover of the TRP that sends the primary and / or secondary PDSCH can also be performed without switching the TRP to which the UE is connected. The primary PDSCH can be a PDSCH sent from the primary TRP or a PDSCH scheduled via the primary PDCCH. The secondary PDSCH can be a PDSCH scheduled via the secondary PDCCH. As another example, the primary PDSCH is the PDSCH that can be preferentially mapped to control plane data compared to other PDSCHs. In the above, the gNB can indicate to the UE the handover of the TRP that sends the primary and / or secondary PDSCH. This indication can be notified using the same signaling as the handover indication of the primary TRP. The handover indication of the TRP that sends the primary PDSCH and the handover indication of the TRP that sends the secondary PDSCH can be performed using the same signaling or different signaling. Thus, for example, scheduling flexibility can be improved.

[0501] The information included in the indication for the TRP handover of sending the primary and secondary PDSCHs can be the same information disclosed as (13) in the indication for the start of random access to the UE from the gNB in ​​Implementation 1.

[0502] For the handover of the TRP that sends the primary and / or secondary PUCCH, the same method as for the handover of the TRP that sends the primary and / or secondary PUCCH can be applied. The primary PUCCH can be a PUCCH sent to the primary TRP, or a PUCCH scheduled through the primary PDCCH. The secondary PUCCH can be a PUCCH scheduled through the secondary PDCCH, or a PUCCH sent by the UE that is different from the primary PUCCH.

[0503] For the handover of TRPs that transmit primary and / or secondary PUCCHs by the UE, the same method as for the handover of TRPs that transmit primary and / or secondary PDSCHs can be applied. The primary PUSCH can be a PUSCH transmitted to the primary TRP or a PUSCH scheduled via the primary PDCCH. The secondary PUSCH can be a PUSCH scheduled via the secondary PDCCH or a PUSCH transmitted by the UE that is different from the primary PUSCH. As another example, compared to other PUSCHs, the primary PUSCH can be a PUSCH that prioritizes mapping control plane information.

[0504] For the handover of TRPs that transmit primary and / or secondary SRSs by the UE, the same method as for the handover of TRPs that transmit primary and / or secondary PDSCHs can be applied. The primary SRS can be an SRS transmitted to the primary TRP or an SRS scheduled through the primary PDCCH. The secondary SRS can be an SRS scheduled through the secondary PDCCH or an SRS transmitted by the UE that is different from the primary SRS.

[0505] The timing of the HARQ response for downlink data in the UE can be derived from the slot number of the uplink communication TRP at the downlink data reception time as a reference. The slot offset from downlink data reception to HARQ response transmission can be a slot offset in units of the slot length in the uplink communication TRP. This slot offset can be statically notified to the UE by the gNB, dynamically notified, or a combination of both. For example, the UE can transmit the HARQ response using the slot number obtained by adding this slot offset to the slot number of the uplink communication TRP at the downlink data reception time. The gNB can use the TA in each TRP and / or the difference between the backhaul delay and the backhaul delay of each TRP to derive the slot number of the uplink communication TRP at the downlink data reception time in the UE. Thus, for example, the UE can also transmit the HARQ response to a TRP that is asynchronous with the downlink communication TRP.

[0506] Even in the SRS transmission timing within the UE, the same method as for the HARQ response timing for downlink data can be used. Thus, for example, the same effect as described above can be achieved.

[0507] The various indicators described in this variation 5 of implementation method 1 can be included in the same signaling for transmission, or different signaling can be used for notification. Multiple signaling can be combined for transmission. Thus, for example, the number of signaling requests from the gNB to the UE can be reduced, resulting in rapid scheduling of the UE from the gNB.

[0508] The UE can use only one MAC entity for a gNB, or it can use multiple MAC entities. For example, the UE can use MAC entities corresponding to the number of primary and secondary PDCCHs. Alternatively, the UE can use one MAC entity for the primary PDCCH and one MAC entity for the secondary PDCCHs. This, for example, improves scheduling flexibility in communications using multiple TRPs.

[0509] The inactivation of the secondary PDCCH can, for example, be used for diversity in applications using multiple TRPs. This, for example, can improve the communication quality between the UE and the gNB.

[0510] The inactivation of the secondary PDCCH can be used, for example, for packet replication using multiple PDCCHs. These multiple PDCCHs can be, for example, a primary PDCCH and a secondary PDCCH. The UE can use the PUSCH scheduled through each PDCCH to send the replicated PDCP packets separately, thereby, for example, improving the reliability of communication between the UE and the gNB.

[0511] According to this variation 5 of embodiment 1, flexible scheduling can be performed without switching connection TRPs. In addition, the reliability of communication can be improved.

[0512] Implementation method 2.

[0513] The UE can communicate in parallel with multiple TRPs and / or beams. For example, the UE can use different beams controlled by the UE to communicate with different TRPs and / or beams.

[0514] Applying the above method can lead to the following problems. For example, if the UE observes that multiple TRPs are located within the same beam range controlled by the UE, the UE cannot communicate in parallel with these multiple TRPs and / or the beam. Consequently, interference occurs between the multiple TRPs during the UE's transmission and reception, resulting in decreased communication reliability and throughput.

[0515] A solution to the above problems is disclosed. The UE will notify the gNB of information regarding whether it can communicate in parallel with multiple TRPs and / or beams.

[0516] This information discloses a solution to the aforementioned problem. The UE notifies the gNB of information regarding whether it can communicate in parallel with multiple TRPs and / or beams. This information may, for example, be a flag indicating whether the UE can communicate in parallel with multiple TRPs and / or beams. This information may also, for example, be information regarding whether multiple transceiver circuits in the UE are supported. This information may also, for example, be information regarding the positional relationship between the UE and the connected TRPs and / or beams. Information related to the aforementioned positional relationship may, for example, be information related to TRPs and / or beams within the range of the same UE-controlled beam. As another example, this information may be information related to combinations of TRPs and / or beams that the UE can transmit and receive in parallel, or information related to combinations of TRPs and / or beams that the UE cannot transmit and receive in parallel.

[0517] This information notification can, for example, use L1 / L2 signaling. For instance, it can use the UCI for CSI reporting, or it can set a new UCI. Thus, for example, the UE can quickly notify the gNB of this information.

[0518] As another example, the UE can send this notification using either MAC signaling or RRC signaling. Thus, for example, the UE can send a large amount of information to the gNB.

[0519] A combination of the above notification methods can be used. For example, information related to whether or not multiple transceiver circuits in the UE are supported can be notified from the UE to the gNB using RRC signaling (e.g., included in the UE's capabilities). Information related to the TRP the UE is connecting to and / or the location relationship between the beam and the UE can also be notified from the UE to the gNB using L1 / L2 signaling. Thus, for example, the amount of signaling from the UE to the gNB can be reduced.

[0520] The gNB can use this notification from the UE to schedule the UE. The gNB can include information related to the TRP and / or beam used by the gNB for downlink data and / or uplink data in the notification of downlink allocation and / or uplink permission for the UE. This information can be, for example, the same information disclosed as example (1) in the random access start indication from the gNB to the UE in Implementation 1. The UE can use this information to control its own beam and to transmit and receive with the gNB. Thus, for example, communication reliability can be improved when the UE uses multiple TRPs and / or beams to transmit and receive with the gNB.

[0521] Other examples of information included in the gNB's notification to the UE regarding downlink allocation and / or uplink clearance could be information related to the beams controlled by the UE (e.g., the identifier of the beams controlled by the UE). As another example, information related to the UE's transit target RP (e.g., the identifier of the TRP) could be included in this information. The UE could notify the base station in advance of information related to the available beams (e.g., the number of available beams). Thus, for example, the same effect as described above can be achieved.

[0522] According to this implementation method 2, interference between TRPs during the transmission and reception of the UE and multiple TRPs can be reduced. As a result, reliability and throughput can be improved.

[0523] Implementation method 3.

[0524] The gNB uses multiple TRPs to communicate with the UE, which increases interference between different TRPs and / or beams. This results in reduced reliability and throughput in communication between the UE and the gNB.

[0525] A solution to the above problem is disclosed. The gNB stops a portion of its subordinate TRPs. The stopped TRPs may be, for example, TRPs that are not connected to UEs under the gNB.

[0526] The aforementioned stopping can be performed without stopping a portion of the signals. For example, the transmission of the SS burst can be continued. This, for example, reduces the power consumption of the TRP, and the gNB can restart the TRP if the UE is within its communication range, resulting in the UE being able to continue communicating with the gNB using the TRP. In the above, the UE can perform the measurement of the SS burst. The UE can notify the gNB of the measurement results of the SS burst. The signal that is not stopped can be CSI-RS, achieving the same effect as described above.

[0527] As another example of the aforementioned stopping mechanism, the transmission frequency of SS bursts can be reduced. This, for example, can further reduce the power consumption of the TRP. In the above, the signal that is not stopped could be, for example, CSI-RS. The same effect as described above can be achieved.

[0528] As another example of the aforementioned shutdown, all transmission and reception within the TRP can be stopped. The base station can restart the TRP operation using the location of nearby TRPs and / or UEs within the beam. This, for example, can further reduce the power consumption of the TRP.

[0529] The candidate TRPs to be stopped can be predetermined. The gNB can then select the TRP to stop from this candidate list. TRPs not belonging to the candidate list can be left unstopped. For example, a TRP with a large communication range could be a candidate TRP. Thus, for example, it is possible to reduce the power consumption of the TRPs while ensuring communication stability within the gNB's TRPs.

[0530] The gNB can broadcast or individually notify subordinate UEs of information related to the TRP termination. As information related to the TRP termination, the following (1) to (4) are disclosed.

[0531] (1) Information related to a stopped TRP.

[0532] (2) Information related to the candidates for the stopped TRP.

[0533] (3) Information related to signals sent in a stopped TRP.

[0534] (4) Combinations of (1) to (3) above.

[0535] In (1) above, the TRP identifier can be used. This, for example, can reduce the signaling volume from the gNB to the UE. As another example, information related to the beam in the TRP can be used. In the above, the beam identifier can be uniquely given by the gNB. The UE can use this indication to determine the TRP it wants to connect to. Thus, for example, if the UE receives SS modules for both a stopped TRP and a non-stopped TRP, the UE can initiate a connection with the non-stopped TRP. As a result, the UE can quickly establish a connection to the TRP.

[0536] The information in (2) above can be the same as the information related to (1) above. Thus, for example, the same effect as that in (1) above can be obtained.

[0537] The information in (3) above may be information related to the type of the signal (e.g., SS burst, CSI-RS), or information related to the period and / or timing offset of the signal transmission. The UE can use this information to perform the signal reception operation in the stopped TRP. Thus, for example, power consumption in the UE can be reduced.

[0538] The method disclosed in Embodiment 3 can be applied to the shutdown of a panel within a TRP. The gNB can broadcast or individually notify its subordinate UEs of information related to panel shutdown. As information related to panel shutdown, the information from the TRP read to the panel in the information (1) to (4) related to TRP shutdown disclosed in Embodiment 3 can be used. This can, for example, reduce interference power in the communication system.

[0539] According to this implementation method 3, interference between TRPs during the transmission and reception of the UE and multiple TRPs can be reduced. As a result, the reliability and throughput between the UE and gNB can be improved.

[0540] Implementation method 4.

[0541] A UE using a DC architecture can send information about an MCG failure to the SCG. In this transmission, for example, a forked bearer can be used. The SCG can then send this information to the MN. The MN can use this information to recover from the MCG failure.

[0542] The above method presents the following problem: During the MCG recovery operation performed by the MN, the signaling between base stations increases. For example, if the SN remains unchanged but the MN switches to another base station, handover requests and responses are generated from the MN before the handover to the MN after the handover, SN addition requests and responses are generated from the MN after the handover to the SN, and SN release requests and responses are generated from the MN before the handover to the SN (see Non-Patent Document 12). This results in the inability to perform MCG recovery quickly.

[0543] A solution to the aforementioned problem is disclosed. For recovery from an MCG failure, a role change between the MN and SN is used. The role change can be performed, for example, by applying the method used in handover disclosed in Non-Patent Document 23 (R2-1802473) to recovery from an MCG failure. Thus, for example, inter-base station signaling during MCG recovery can be reduced, resulting in rapid MCG recovery.

[0544] The MN can determine whether a task handover has been performed. This determination can be made, for example, using information about an MCG fault notified by the UE via the SCG. Thus, for example, an MCG recovery operation can be initiated quickly after an MCG fault.

[0545] The MN can notify the SN of a role change request. This request may contain information related to the MN settings used for the connection between the MN and the UE. The SN can use this information to establish a connection with the UE after the role change. The SN can also notify the MN of a role change response. This response may contain information related to the SN settings used for the connection between the SN and the UE. The MN can use this information to establish a connection with the UE after the role change.

[0546] During recovery from an MCG failure, the SN may not use the MN as the post-handover SN. The SN can use the task handover request from the MN to determine whether to use the MN as the post-handover SN. The SN can include information related to whether to use the MN as the post-handover SN in the task handover response to the MN notification and notify the MN. The MN can use this information to release the connection with the UE. Thus, for example, a flexible NW structure can be achieved in the communication system, and the UE can quickly release the MN before handover.

[0547] As another example, the SN can include an SN release request in the task handover response and notify the MN. The SN release request can be communicated using different signaling than the task handover response. Thus, for example, the inter-base station signaling in the MN's release before the handover can be reduced.

[0548] The MN can send configuration change instructions to the UE, such as RRC connection reconfiguration signaling, via the SCG. This transmission can, for example, use a forked SRB. Thus, even in the event of an MCG failure, the MN can still send configuration change instructions to the UE, resulting in the UE being able to quickly perform MCG recovery.

[0549] The UE can send a configuration change instruction, such as a response to reconfiguration of an RRC connection, to the SN. By receiving this response, the SN can act as the MN after the handover.

[0550] As another example, the SN can send a configuration change instruction to the UE, such as signaling for RRC connection reconfiguration. In the above, the SN can perform connection configuration with the UE after a task handover. This transmission can use an SRB terminated by the SN, such as SRB3. The UE can send a configuration change instruction, such as a response for RRC connection reconfiguration, to the SN. Thus, for example, signaling between base stations can be reduced.

[0551] Figure 35 This is a diagram illustrating the actions of switching between recovery application tasks from an MCG failure. Figure 35 The example shown illustrates the release of MN without switching.

[0552] exist Figure 35In step ST4001, the UE detects an MCG failure. The reason for MCG failure detection could be, for example, an RLF (Related Flow Fault) in the MCG. In step ST4003, the UE sends an MCG failure indication to the SN. A forked SRB (Search Service Block Recognition) is used in step ST4003. In step ST4004, the SN transmits the MCG failure indication received in step ST4003 to the MN.

[0553] exist Figure 35 In step ST4005, the MN decides to perform a role change with the SN, switching between the primary and secondary base stations. In step ST4007, the MN sends a role change request to the SN. This request may include UE configuration information from the MN. In step ST4009, the SN notifies the MN of a role change response. This response may include UE configuration information from the SN, and may also include information indicating whether to maintain the secondary base station after the role change. Figure 35 In the example shown, the secondary base station is maintained after the task switch.

[0554] exist Figure 35 In step ST4011, MN sends a signaling message to SN to notify UE of RRC connection reconfiguration. In step ST4012, SN sends the RRC connection reconfiguration signaling received in step ST4011 to UE. This transmission can use a forked SRB. UE uses step ST4012 to perform settings related to task handover between MN and SN. In step ST4013, UE notifies SN, the primary base station after task handover, that RRC connection reconfiguration is complete. In step ST4015, SN notifies MN, the secondary base station after task handover, that secondary base station reconfiguration is complete (SN reconfiguration complete).

[0555] exist Figure 35 In step ST4017, the UE sends an RA preamble to the MN. In step ST4019, the MN sends an RA response to the UE.

[0556] exist Figure 35 In step ST4021, the SN sends a path switch request to the AMF. In step ST4023, the AMF sends a path switch response to the SN.

[0557] exist Figure 35The example illustrates the case where MN is maintained as the secondary base station after handover, but MN can also be released. In the above cases, the random access process shown in steps ST4017 and ST4019 between the UE and MN can be omitted. Thus, for example, the complexity of the UE's MCG recovery process can be avoided.

[0558] According to this embodiment 4, the signaling volume in the MCG recovery operation can be reduced, resulting in the ability to quickly execute the MCG recovery operation in the UE.

[0559] Variation 1 of Implementation Method 4.

[0560] In Implementation 4, an example of using a forked SRB to notify MCG fault information in the DC structure was disclosed, but an SRB terminated by the SN, namely SRB3, can also be used. For example, without setting a forked SRB, the UE can notify the SN of MCG fault information.

[0561] The above method presents the following problem: Due to MN startup, the MN-SN task handover cannot be applied when the UE uses SRB3 to notify of an MCG fault. This results in a failure to quickly recover from an MCG fault.

[0562] A solution to the above problems is disclosed. The SN initiates task handover. The SN can determine whether task handover has been performed. This determination can, for example, be made using MCG fault information notified to the SN by the UE. Thus, for example, MCG recovery operations can be initiated quickly after an MCG fault.

[0563] The SN can notify the MN of a role change request. This notification may contain information related to the SN settings used for the connection between the SN and the UE.

[0564] The SN may choose not to use the MN as the post-handover SN. The SN can use the MCG fault information notification from the UE to determine whether to use the MN as the post-handover SN. The SN can include information related to whether to use the MN as the post-handover SN in the task handover request notification to the MN and notify the MN accordingly. Thus, for example, it can become a flexible NW structure in the communication system, and the UE can quickly release the MN before handover.

[0565] As another example, the SN can include an SN release request in the task handover response and notify the MN. The SN release request can be communicated using different signaling than the task handover response. Thus, for example, the inter-base station signaling in the MN's release before the handover can be reduced.

[0566] The MN can notify the SN of a role change response. This notification may contain information related to the MN settings used for the connection between the MN and the UE. The SN can use this information to configure the connection with the UE after the role change.

[0567] The SN can send configuration change instructions to the UE, such as RRC connection reconfiguration signaling. This transmission can, for example, use SRB3. Thus, for example, even in the state of MCG failure, the MN can send configuration change instructions to the UE, resulting in the UE being able to quickly perform MCG recovery.

[0568] The UE can send a configuration change instruction, such as a response to reconfiguration of an RRC connection, to the SN. By receiving this response, the SN can act as the MN after the handover.

[0569] As another example, the MN can send a configuration change instruction to the UE, such as an RRC connection reconfiguration signal, via the SCG. In the above, the MN can perform connection configuration with the UE after a task handover. This transmission can use a forked SRB. The UE can send a response to the configuration change instruction, such as an RRC connection reconfiguration, to the SN. Thus, for example, the complexity of the design in the communication system can be avoided.

[0570] Figure 36 This is a diagram illustrating the actions of switching between recovery application tasks from an MCG failure. Figure 36 The example shown illustrates the release of MN without switching. Figure 36 In the middle, to and Figure 35 Common processes are appended with the same step numbers, and common descriptions are omitted.

[0571] Figure 36 The steps shown in ST4001 and Figure 35 same.

[0572] exist Figure 36 In step ST4103, the UE sends an MCG failure indication to the SN. SRB3 is used in step ST4103. In step ST4105, the SN decides to perform a task handover between the secondary and primary base stations with the MN. In step ST4107, the SN sends a role change request to the MN. This role change request may contain UE configuration information from the SN, or information indicating whether to maintain the secondary base station after the task handover. Figure 36In the example shown, the secondary base station is maintained after the task handover. In step ST4109, the MN notifies the SN of the role change response. This role change response may contain UE configuration information from the MN.

[0573] exist Figure 36 In step ST4111, the SN sends an RRC connection reconfiguration signaling message to the UE. This transmission can use SRB3. The UE uses step ST4111 to perform settings related to task handover between the MN and SN.

[0574] Figure 36 The steps ST4013 to ST4023 shown are... Figure 35 same.

[0575] exist Figure 36 In the example, with Figure 35 Similarly, the case of maintaining MN as the secondary base station after handover is shown, but MN can also be released. In the above cases, the random access process shown in steps ST4017 and ST4019 between the UE and MN can be omitted. Thus, for example, the complexity of the UE's MCG recovery process can be avoided.

[0576] Implementation method 4 and its variation 1 can also be used in combination. For example, which branch of SRB and SRB3 is used in the MCG fault notification from the UE can be statically determined by a standard. This, for example, avoids complexity in the communication system.

[0577] As an example of statically determining the bearer used for MCG fault notifications from the UE through a standard, a forked SRB can be used. For example, in the UE's DC settings, a forked SRB can be used if both forked SRB and SRB3 are configured, and / or if only forked SRB is configured. This, for example, avoids the complexity of installing the MCG fault notification function in the communication system.

[0578] As another example, SRB3 can be used. For instance, in the UE's DC settings, SRB3 can be used when both Bifurcation SRB and SRB3 are configured, and / or when only SRB3 is configured. This, for example, can reduce the amount of inter-base station signaling during recovery from an MCG failure.

[0579] As another example of which bearer, SRB or SRB3, is used in an MCG fault notification from the UE, the base station can determine the bearer to use and notify the UE accordingly. This, for example, improves flexibility in the communication system. The notification can be made using RRC signaling. This RRC signaling can be, for example, signaling for the initial connection between the UE and the primary base station, or signaling for the UE's handover to the primary base station. As other examples, the RRC signaling can be signaling for SN addition, SN modification, or SN change.

[0580] As another example relating to the combination of Embodiment 4 and this variation 1 of Embodiment 4, the choice of which bearer, SRB or SRB3, to use in the signaling for reconfiguring the RRC connection of the UE from the network side (primary base station or secondary base station) can be determined in the same way as the MCG fault notification from the UE. Thus, for example, the same effect as described above can be obtained. As another example, the same bearer as the MCG fault notification from the UE can be used, or a different bearer can be used.

[0581] According to this variation 1 of embodiment 4, the signaling amount in the MCG recovery operation can be reduced, resulting in the ability to quickly execute the MCG recovery operation in the UE.

[0582] Implementation method 5.

[0583] In 3GPP, due to D2D (Device to Device) communication and V2V (Vehicle to Vehicle) communication, Side Link (SL) is supported (see Non-Patent Document 1). SL is defined through the PC5 interface.

[0584] The physical channel used for SL (refer to Non-Patent Document 1) is described below. The Physical Sidelink Broadcast Channel (PSBCH) transmits information related to system synchronization and is sent from the UE.

[0585] The Physical Sidelink Discovery Channel (PSDCH) transmits sidelink discovery messages from the UE.

[0586] The Physical Sidelink Control Channel (PSCCH) transmits control information from the UE for sidelink communication and V2X sidelink communication.

[0587] The Physical Sidelink Shared Channel (PSSCH) transmits data from the UE for use in both sidelink and V2X sidelink communication.

[0588] The transmission channel used for SL (refer to Non-Patent Document 1) will be described. The Sidelink broadcast channel (SL-BCH) has a predetermined transmission channel format and is mapped to the PSBCH, which is the physical channel.

[0589] The Sidelink Discovery Channel (SL-DCH) is a periodically broadcast channel with a fixed size and a pre-defined format. The SL-DCH supports both UE autonomous resource election and resource allocation via eNB scheduling. While there is a risk of conflict in UE autonomous resource election, there are no conflicts when allocating dedicated resources to the UE via the eNB. The SL-DCH also supports HARQ merging. However, the SL-DCH does not support HARQ feedback. The SL-DCH is mapped to the PSDCH, which is a physical channel.

[0590] The Sidelink Shared Channel (SL-SCH) supports broadcast transmission. SL-SCH supports both UE autonomous resource selection and resource allocation via eNB scheduling. While there is a risk of conflict in UE autonomous resource selection, there are no conflicts when allocating dedicated resources to the UE via the eNB. Additionally, SL-SCH supports HARQ merging. However, SL-SCH does not support HARQ feedback. Furthermore, SL-SCH supports dynamic link adaptation by changing transmit power, modulation, and merging. SL-SCH is mapped to the PSSCH, which serves as the physical channel.

[0591] The logical channel used for SL (refer to Non-Patent Document 1) will be described. The Sidelink Broadcast Control Channel (SBCCH) is a straight-link channel used to broadcast straight-link system information from one UE to other UEs. The SBCCH is mapped to the SL-BCH, which serves as the transport channel.

[0592] The Sidelink Traffic Channel (STCH) is a one-to-many direct-link traffic channel used to send user information from one UE to other UEs. STCH is only used by UEs with direct-link communication capabilities and UEs with V2X direct-link communication capabilities. One-to-one communication between two UEs with direct-link communication capabilities is also achieved through STCH. STCH is mapped to SL-SCH, which serves as the transport channel.

[0593] SL supports the use of multiple carriers. Figure 37 This is a conceptual diagram illustrating the use of multi-carrier communication in SL. The eNB and UE communicate via interface Uu. Uplink communication occurs from the UE to the eNB, and downlink communication occurs from the eNB to the UE. UEs communicate with each other via interface PC5.

[0594] SL uses one or more carriers (carrier #0 to carrier #n) to communicate from one UE (UE#1) to one or more UEs (UE#2 to UE#4).

[0595] The resources used for PSCCH and PSSCH are configured on one carrier of the SL. When multiple carriers are configured in the SL, the resources used for PSCCH and PSSCH are configured separately on each carrier, so the PSCCH timing and PSSCH timing are different on each carrier.

[0596] In the SL, the transmitting UE (UE_tx) transmits PSCCH and PSSCH at different timings on each carrier. If the PSCCH and PSSCH timings are different on each carrier, the receiving UE (UE_rx) in the SL needs to receive PSCCH and PSSCH from each carrier with different timings, thus increasing power consumption.

[0597] Increased power consumption leads to faster battery drain and reduced communication time. For example, in the case of a pedestrian terminal (UE_rx), the terminal typically has only a small-capacity battery, so increased power consumption becomes a problem. In this embodiment 5, a method for solving the above-mentioned problems is disclosed.

[0598] The PSSCH is set to the same timing on multiple carriers of SL. In other words, the transmission timing of PSSCH is set to be the same on multiple carriers of SL. The setting method is disclosed. The resource timing of PSSCH on each carrier is set to be the same. The parameters in the time axis direction of the PSSCH scheduling information are set to be the same. The scheduling information of PSSCH resources is included in SCI, and PSCCH is used to notify UE_rx from UE_tx. PSCCH and PSSCH are transmitted on each carrier, and PSSCH and PSSCH are transmitted on the same carrier.

[0599] The scheduling information of the PSCCH for each carrier is included in the DCI, and the UE_tx is notified from the eNB using the PDCCH. The UE_tx can receive the scheduling information of the PSCCH for each carrier by receiving the PDCCH.

[0600] Alternatively, UE_tx can select the resources to utilize in the PSCCH and / or PSSCH of each carrier. The eNB informs UE_tx in advance of the available resources in the PSCCH and / or PSSCH for each carrier. These available resources can be provided as a resource pool. UE_tx can then select the resources to utilize from the resources available for each carrier as notified by the eNB.

[0601] The resources available in the PSCCH and / or PSSCH of each carrier can be pre-configured within the UE_tx. For example, this resource information can be stored in the SIM of the UE_tx by an operator. The UE_tx can then select the resources to utilize from the pre-configured resources available for each carrier.

[0602] The UE_tx can perform sensing processing as a method for selecting resources to utilize in the PSCCH and PSSCH of each carrier. As a sensing process, the UE_tx measures the received power or received signal strength of resources available in the PSSCH that are pre-notified from the eNB or pre-set in the UE_tx. A specified threshold can be set for the measurement results to select resources.

[0603] For example, the available resources in the PSSCH are determined for each RB. RBs whose measurement results exceed a specified threshold are set as unselectable, while RBs whose measurement results are below the specified threshold are set as selectable. The determination can be performed on each RB or on multiple RBs. Thus, UE_tx can select the resources used in the PSCCH and PSSCH of each carrier.

[0604] Figure 38 and Figure 39 This is an example of a sequence of PSSCHs used to set the same timing on multiple carriers. Figure 38 and Figure 39 Connect at the boundary line BL3839. Figure 38 and Figure 39 The example shows the case where four carriers are used as SL communication carriers.

[0605] In step ST4901, the eNB notifies the PC5 of the resource settings for UE_tx and UE_rx. The PC5 resource settings include a carrier list containing information for one or more carriers, and resource pool settings for each carrier. The carrier list may contain frequency information for each carrier. The PC5 resource settings can be included in system information for broadcasting, or they can be included in RRC information for notification using dedicated RRC signaling.

[0606] In step ST4902, the UE_tx generated by the data transmitted in PC5 requests resources from the eNB for PC5 communication. This request is included in the RRC information and is notified using dedicated RRC signaling. An SR or BSR can be included in this request message for notification. Thus, the eNB recognizes that the UE_tx has data to transmit on PC5.

[0607] In step ST4903, the eNB notifies the UE_tx of carrier messages and PSCCH scheduling information via PDCCH. This information can be included in the DCI for notification. The format of the DCI containing this information can be newly configured. Alternatively, this information can be included in an existing DCI5A for notification. As carrier information, an identifier or label used to determine the carrier can be used. The carrier information can be pre-associated with each carrier in the carrier list. The carriers in the carrier list of step ST4901 can be determined.

[0608] For example, in step ST4903, information related to carrier number 0 is notified. This PSCCH scheduling information can be included in the scheduling information of the resources for PSCCH transmitted on carrier number 0. UE_tx recognizes that carrier number 0 can be transmitted and can determine the PSCCH resources on that carrier.

[0609] Similarly, in step ST4904, the eNB uses the PDCCH to notify UE_tx of carrier messages and PSCCH scheduling information. UE_tx recognizes that it can transmit carrier number 1 and can determine the PSCCH resources on that carrier.

[0610] Similarly, in step ST4905, the eNB uses the PDCCH to notify UE_tx of carrier messages and PSCCH scheduling information. UE_tx recognizes that it can transmit carrier number 2 and can determine the PSCCH resources on that carrier.

[0611] Similarly, in step ST4906, the eNB uses the PDCCH to notify UE_tx of carrier messages and PSCCH scheduling information. UE_tx recognizes that it can transmit carrier number 3 and can determine the PSCCH resources on that carrier.

[0612] From step ST4903 to step ST4906, the eNB transmits carrier information and PSCCH resource scheduling information to UE_tx for each carrier using the PDCCH. Alternatively, the eNB can transmit the carrier information and PSCCH resource scheduling information for each carrier using a single PDCCH. The eNB can include the carrier information and PSCCH resource scheduling information for one carrier in a single DCI, or it can include the corresponding DCIs for multiple carriers in a single PDCCH. Thus, the eNB uses this single PDCCH to notify UE_tx of the carrier information and PSCCH resource scheduling information for that single carrier.

[0613] Therefore, UE_tx only needs to receive the PDCCH once, thus enabling it to receive the aforementioned information from each carrier earlier. Furthermore, by reducing the number of receptions, the power consumption of UE_tx can be reduced.

[0614] In addition, while the above method includes each carrier's DCI separately in the PDCCH, it is also possible to include information from multiple carriers and scheduling information for each carrier's PSCCH resources in a single DCI. The eNB includes this information in a single DCI, which is contained within a single PDCCH, thus enabling the eNB to notify the UE_tx of this information using only one PDCCH. Therefore, multiple DCIs are not required, allowing for earlier reception of DCI information.

[0615] As a method of representing multiple carrier information using a single DCI, bit mapping can be used, for example. A mapping of the carrier numbers in the carrier list shown in step ST4901 is established, and the information of which carrier it is can be represented using the bits corresponding to that carrier. For example, the mapping can be pre-dated from the LSBs of the bit mapping, following the ascending order of the carrier list. Thus, information of multiple carriers can be represented with fewer bits.

[0616] In step ST4907, UE_tx performs sensing processing on each carrier (carrier number 0, carrier number 1, carrier number 2, carrier number 3) to search for resources for PSSCH. During the sensing processing, for example, other UEs detect resources not used in SL communication. UE_tx can use the resource pool settings for each carrier notified in step ST4901. UE_tx determines the available resources through the sensing processing.

[0617] The eNB can notify the UE_tx of the PSSCH scheduling information in steps ST4903 to ST4906. Thus, the UE_tx can determine the PSSCH scheduling information. In this case, the sensing processing for each carrier in step ST4907 can be omitted.

[0618] When the eNB notifies the UE_tx of the PSSCH scheduling information, the eNB can allocate PSSCH transmission resources with the same timing across all carriers for this notification. Therefore, the UE_tx can allocate PSSCH transmission resources with the same timing across all carriers.

[0619] Steps ST4902 to ST4906, whereby the eNB notifies the UE_tx, can be omitted. In this case, the UE_tx can use the resource pools of each carrier received from the eNB in ​​step ST4901, and perform sensing processing on each carrier in step ST4907. Thus, the UE_tx can select resources and carriers with the same timing for PSSCH transmission.

[0620] In step ST4908, UE_tx selects resources with the same timing on multiple carriers from the determined available resources. Alternatively, UE_tx can select carriers with the same timing from the determined available resources. Thus, UE_tx selects multiple carriers with resources having the same timing. Figure 38 and Figure 39 In the example, carriers with resources having the same timing are designated as carrier number 0, carrier number 1, and carrier number 3.

[0621] In step ST4909, UE_tx notifies UE_rx of PSSCH scheduling information using PSCCH with carrier number 0. Similarly, in step ST4910, UE_tx notifies UE_rx of PSSCH scheduling information using PSCCH with carrier number 1. Similarly, in step ST4911, UE_tx notifies UE_rx of PSSCH scheduling information using PSCCH with carrier number 3.

[0622] The scheduling information of PSSCH can be set to the scheduling information of the resources with the same timing selected in step ST4908. The scheduling information of resources on the time axis can be the same as that of other carriers. The scheduling information of resources on the frequency axis can be the same as that of other carriers or different.

[0623] PSSCH resource timing can be periodic. Alternatively, PSSCH resource timing can also be semi-permanent.

[0624] In step ST4912, UE_tx transmits data using the PSSCH of carrier number 0. In step ST4913, UE_tx transmits data using the PSSCH of carrier number 1. In step ST4914, UE_tx transmits data using the PSSCH of carrier number 3.

[0625] In steps ST4909, ST4910, and ST4911, UE_rx receives PSCCH on carriers labeled 0, 1, and 3, and receives data from UE_tx on each carrier through the scheduling information of the PSCCH contained in the PSCCH of each carrier.

[0626] By adopting the method disclosed in Embodiment 5, the resource timing of the PSSCH for each carrier can be set to be the same on an SL that supports multiple carriers. Therefore, the power consumption of UE_rx can be reduced.

[0627] Variation 1 of Implementation Method 5.

[0628] In the method disclosed in Implementation 5, for multiple carriers used for SL, scheduling with the same resource timing for each carrier is required. Therefore, the amount of information becomes enormous, and the amount of resources required for control increases. This leads to an increase in the overhead necessary for data transmission. In this variation 1, a method for solving this problem is disclosed.

[0629] The eNB sets up candidate carrier information for scheduling with the same resource timing. This is called candidate carrier information. The eNB notifies the UE_tx of the candidate carrier information. The candidate carrier information can be included in the DCI and notified using PDCCH. The candidate carrier information can be dynamically set according to the needs of the UE_tx. As another notification method, the candidate carrier information can be notified as RRC information using RRC signaling. Alternatively, the candidate carrier information can be notified as MAC information using MAC signaling. Because retransmission control is performed, the reception error rate can be reduced.

[0630] The carrier information used for PSCCH scheduling is set up. This is called PSCCH carrier information. Among multiple carriers scheduled for the same resource timing, PSCCH is transmitted on one carrier. PSCCH carrier information is the information for that single carrier from which PSCCH is transmitted. The eNB notifies the UE_tx of the PSCCH carrier information. The notification method can be the same as that used for candidate carrier information.

[0631] The carrier information used for scheduling the same resources during timing is set. This is called the carrier usage information. UE_tx notifies UE_rx of the carrier usage information. The carrier usage information can be included in the SCI and notified using PSCCH.

[0632] The PSCCH of the carrier is used to notify the PSSCH scheduling information. As PSSCH scheduling information, PSSCH scheduling information with the same resource timing set across multiple carriers can be used. UE_tx can include this information in the SCI and notify UE_rx using the PSCCH of the carrier.

[0633] In PSSCH resource settings, not only resource timing but also resources on the frequency axis can be set to the same configuration. Frequency direction offsets and resources derived from those offsets can be set. The offset can be set, for example, based on the lowest subcarrier within the carrier. The setting unit can be, for example, a subcarrier unit, a PRB unit, etc. As scheduling information, scheduling information for PSSCHs with the same resources configured across multiple carriers can be used. By setting the PSSCH resource settings identical across all carriers, the amount of information required for notification from UE_tx to UE_rx can be reduced. The amount of information required for notification using PSCCH can also be reduced.

[0634] Figure 40 This is a variation of implementation 5, an example of setting the PSCCH and PSSCH sequences with the same timing on multiple carriers. Figure 40 The example shows the case where four carriers are used as SL communication carriers.

[0635] Steps ST5001, ST5002 and Figure 38 and Figure 39 Steps ST4901 and ST4902 are the same, so the explanation is omitted here.

[0636] In step ST5003, the eNB notifies the UE_tx of candidate carrier information, PSCCH carrier information, and PSCCH scheduling information via PDCCH. This information can be included in the DCI for notification. The format of the DCI containing this information can be newly configured. Alternatively, this information can be included in the existing DCI5A for notification. As candidate carrier information, an identifier or label used to determine the carrier can be used. The candidate carrier information can be pre-associated with each carrier in the carrier list. The carriers in the carrier list of step ST5001 can be determined.

[0637] For example, candidate carrier information can be set to carrier numbers 0, 1, 2, and 3. For example, PSCCH carrier information can be set to carrier number 0. As scheduling information for the PSCCH, it can be included in the scheduling information of the resources for the PSCCH transmitted on carrier number 0.

[0638] The UE_tx identifies carriers 0, 1, 2, and 3 as transmittable based on the candidate carrier information. Additionally, the UE_tx identifies the carrier with carrier number 0 as the location for PSCCH transmission based on the PSCCH carrier information. Furthermore, the UE_tx identifies the PSCCH resources used on carrier number 0 based on the PSCCH scheduling information.

[0639] In step ST5004, UE_tx performs sensing processing on candidate carriers (carrier number 0, carrier number 1, carrier number 2, and carrier number 3) to search for resources for PSSCH. UE_tx can use the resource pool settings for each carrier notified in step ST5001. UE_tx determines the available resources through sensing processing.

[0640] In step ST5003, the eNB can notify the UE_tx of the carrier information to be used. Additionally, in step ST5003, the eNB can notify the UE_tx of the PSSCH scheduling information. Thus, the UE_tx can determine the PSSCH scheduling information. In this case, the sensing processing for each carrier in step ST5004 can be omitted.

[0641] When the eNB notifies the UE_tx of the PSSCH scheduling information, the eNB can allocate PSSCH transmission resources with the same timing across all carriers for this notification. Therefore, the UE_tx can allocate PSSCH transmission resources with the same timing across all carriers.

[0642] Steps ST5002 to ST5003, whereby the eNB notifies the UE_tx, can be omitted. In this case, the UE_tx can use the resource pools of each carrier received from the eNB in ​​step ST5001, and perform sensing processing on each carrier in step ST5004. Thus, the UE_tx can select resources and carriers with the same timing for PSSCH transmission.

[0643] In step ST5005, UE_tx selects resources with the same timing on multiple carriers from the determined available resources. Alternatively, UE_tx can select carriers with the same timing from the determined available resources. Thus, UE_tx selects multiple carriers with resources having the same timing. Figure 40 In the example, carriers with resources having the same timing are designated as carrier number 0, carrier number 1, and carrier number 3.

[0644] In step ST5006, UE_tx notifies UE_rx of the carrier information to be used. UE_tx, in turn, notifies UE_rx of the PSSCH scheduling information using the PSCCH with carrier number 0. Here, as the carrier information to be used, carrier numbers 0, 1, and 3 are notified. The PSSCH scheduling information can use the scheduling information of resources with the same timing selected in step ST5005.

[0645] Resources on the time axis can be set to be the same across all carriers in use. Only scheduling information on the time axis is needed. Resources on the frequency axis can be the same or different across all carriers in use. If they are the same, only scheduling information on the frequency axis is needed. If they are different, each carrier can be pre-associated with its corresponding scheduling information.

[0646] PSSCH resource timing can be periodic. Alternatively, PSSCH resource timing can also be semi-permanent.

[0647] In step ST5006, it is shown that UE_tx sends a PSCCH using a carrier to UE_rx. UE_rx receives the PSCCH using a carrier, and therefore can receive PSCCHs of carriers in the carrier list. For example, UE_rx can identify the PSCCH using a carrier by receiving a PSCCH containing carrier usage information and PSCCH scheduling information. UE_rx can stop receiving further PSCCHs of carriers upon receiving a PSCCH using a carrier.

[0648] Other methods for UE_rx to obtain PSCCH carrier information are disclosed. The eNB can include the PSCCH carrier information in the information notified in step ST5001 for notification. The PSCCH carrier information can be included in the SIB for broadcasting. Both UE_tx and UE_rx can identify the PSCCH carrier information. UE_tx can determine the PUCCH carrier in step ST5006. UE_rx can receive only the PSCCH using the PSCCH carrier in step ST5006.

[0649] The eNB can include the PSCCH scheduling information in the information notified in step ST5001 for notification. It can also include the PSCCH scheduling information in the SIB for broadcasting. Both UE_tx and UE_rx can recognize the PSCCH scheduling information. Both UE_tx and UE_rx can recognize the PSCCH resources used on the PUCCH carrier in step ST5006.

[0650] The eNB can include the candidate carrier information in the information notified in step ST5001 for notification. The eNB can also include the candidate carrier information in the SIB for broadcasting. The UE_tx can identify the candidate carrier information. In step ST5004, the UE_tx can sense the carrier of the candidate carrier.

[0651] By notifying the PSCCH carrier information, PSCCH scheduling information, and candidate carrier information in step ST5001, the eNB can omit the signaling from steps ST5002 to ST5003. For example, this can be applied to situations where resources are utilized in the PSCCH selection of each carrier by the UE_tx.

[0652] In step ST5007, UE_tx transmits data using the PSSCH of carrier number 0. In step ST5008, UE_tx transmits data using the PSSCH of carrier number 1. In step ST5009, UE_tx transmits data using the PSSCH of carrier number 3.

[0653] In step ST5006, UE_rx receives the PSCCH of the PSCCH carrier and receives data from UE_tx on carriers labeled 0, 1, and 3 using the PSCCH scheduling information contained in the PSCCH.

[0654] Other methods for UE_rx to obtain scheduling information of the PSSCH of the used carrier are disclosed. The used carrier information and PSSCH scheduling information can be notified from the PSSCH of all carriers included in the candidate carrier. If UE_rx receives any PSSCH of the candidate carrier, it can obtain the scheduling information of the used carrier and PSSCH. This reduces the UE_rx's reception processing and power consumption.

[0655] By using the method disclosed in this variation 1, which is embodiment 5, the same effects as embodiment 5 can be achieved. Furthermore, the amount of information required for multi-carrier communication in the SL can be reduced. The amount of resources required for notification from the eNB to UE_tx and from UE_tx to UE_rx can be reduced, thus aiming to reduce the overhead of data communication in the SL.

[0656] In Embodiment 5 and its variation 1, UE_tx performs sensing on each carrier. This is because resources used for SL communication may be used by other UE_tx. When SL communication resources are used by other UE_tx, it becomes impossible to select resources with the same timing from multiple carriers. Assume multiple UEs are communicating in V2V or V2P communication. For example, if these multiple UEs use resources for SL communication, a situation arises where resources with the same timing cannot be selected from multiple carriers.

[0657] A method for resolving the above problems is disclosed. A dedicated resource pool is set up to provide the same timing resource across multiple carriers. By distinguishing it from existing resource pools, the same timing resource can be easily selected from multiple carriers. This is used as a setting for PC5 resources. Figure 38 and Figure 39 Step ST4901 in the example Figure 40 In step ST5001 of the example, a dedicated resource pool setting can be notified for the same timing resource settings across multiple carriers. This resource pool setting can be related to... Figure 38 Example steps ST4901 and Figure 40 In the example, the resource pool settings for each carrier of ST5001 are configured and notified separately.

[0658] This prevents situations where resources with the same timing cannot be selected from multiple carriers. It also easily reduces the power consumption of UE_rx.

[0659] In Variation 1 of Implementation Method 5, the eNB sets the PSCCH carrier and notifies the UE_tx. Alternatively, the UE may set the PSCCH carrier. The eNB may not notify the UE_tx of the PSCCH carrier.

[0660] The method disclosed allows UE_tx to select multiple carriers with resources having the same timing. UE_tx then selects the carrier for the PSCCH from the selected carriers. For example, in... Figure 40 This process can be implemented in step ST5005.

[0661] UE_tx uses the PSCCH carrier it has selected to notify UE_rx of the carrier information and PSSCH scheduling information. This information can be included in the SCI1 of the PSCCH on the selected PSCCH carrier. For example, in... Figure 40 This process can be implemented in step ST5006.

[0662] Therefore, the UE can select the carrier for transmitting the PSCCH, and thus can select a carrier with good communication quality for the SL. By improving the communication quality of the control channel in the SL, the reliability of data communication in the SL can be improved.

[0663] In NR, SUL (Supplementary Uplink) is supported (see Non-Patent Document 16). SL can be constructed on SUL. As a carrier for SL, a carrier configured as SUL can be used.

[0664] For example, when configuring PC5 resources for D2D and V2V UEs, the eNB configures a carrier designated as SUL for PC5 use. In this case, information indicating SUL can be set. When configuring the carrier for SUL using RRC, a label is pre-marked as the carrier for SUL use, and this label can be used as information indicating SUL.

[0665] Additionally, a corresponding SUL carrier can be pre-assigned to each non-SUL carrier. The carrier labels for non-SUL carriers and SUL carrier labels can be pre-assigned.

[0666] Allocate channels for SL on carriers configured as SUL. For example, PSCCH and PSSCH can be allocated on carriers configured as SUL.

[0667] The methods disclosed in Embodiment 5 and Variation 1 of Embodiment 5 can be applied in SL communication using SUL.

[0668] SUL and non-SUL can be used in SL communication. SL communication is performed using both SUL and non-SUL carriers. SUL and non-SUL can be switched. For example, this switching can be performed dynamically. For example, the method of setting the resource timing of PSSCH in multiple carriers to the same value, as described in Embodiment 5 and its variation 1, can be appropriately applied. Therefore, since the resource timing of PSSCH is the same, SUL and non-SUL can be switched dynamically.

[0669] The handover between SUL and non-SUL can be performed using the control channel on any carrier. For example, the handover can be performed using the PSCCH of the carrier. Information indicating the handover between SUL and non-SUL can be included in the SCI. This SCI can be notified from UE_tx to UE_rx using the PSCCH of the carrier. The carrier settings used can be used as information indicating the handover between SUL and non-SUL.

[0670] For example, when using SUL, the SUL carrier setting is used as information indicating handover. When using non-SUL, the non-SUL carrier setting is used as information indicating handover. Information indicating handover between SUL and non-SUL, along with resource allocation information, can be included in the SCI.

[0671] For example, it can be Figure 40 The ST5006 PSCCH uses this information in the SCI of the carrier-based PSCCH for notification. UE_tx determines which SUL or non-SUL to use and includes this information in the SCI to notify UE_rx using the carrier-based PSCCH.

[0672] Upon receiving a PSCCH using a carrier, the UE_rx can identify the handover between SUL and non-SUL carriers, i.e., which carrier (SUL or non-SUL) is used for PSCCH transmission. Additionally, the UE_rx can receive the PSCCH by receiving scheduling information for the PSCCH.

[0673] It is disclosed that the PSCCH of which carrier can be used to notify information indicating a handover between SUL and non-SUL. As another example, the PSCCH of one of multiple carriers communicating in SL can actually be used to notify information indicating a handover. For example, it is possible to utilize... Figure 39 The PSCCH with carrier number 0, as shown in step ST4909, is used to notify the handover information. This is also effective for setting a corresponding SUL carrier for each non-SUL carrier.

[0674] Therefore, when a SUL is configured in the NR, an SUL can be constructed on a carrier with a configured SUL, and SL communication can be performed. By using SUL, the coverage of communication in SL can be expanded, and the reliability of SL communication can be improved.

[0675] The use of SUL in SL communication is disclosed, but it can also be used in V2X communication using the Uu interface. SUL can be used on the uplink of V2X communication using Uu. Furthermore, switching between SUL and non-SUL is possible on the uplink of V2X communication using Uu. Therefore, when SUL is configured in NR, V2X communication using Uu can be performed on carriers with SUL configured, expanding the coverage of V2X communication and improving the reliability of V2X communication.

[0676] Implementation method 5 and its variation 1 disclose a method for setting the resource timing of PSSCH in multiple carriers to be the same. This timing can be different. It can be consistent within a specified range. The specified range can be predetermined using standards, etc. For example, the specified range can be set as a timing window. The setting unit can be, for example, a symbol unit, a micro-slot unit, a slot unit, a subframe unit, a TTI unit, a short TTI unit, etc. This provides scheduling flexibility. Furthermore, since UE_rx can receive within this specified range, it also has the effect of reducing power consumption.

[0677] In Embodiment 5 and Embodiment 5 Modification 1, an eNB is listed as the base station, but a gNB can also be used. When SL is supported in NR, the method disclosed in Embodiment 5 and Embodiment 5 Modification 1 can also be appropriately applied to achieve the same effect.

[0678] Implementation method 6.

[0679] In 3GPP, two paths were studied for V2V communication within the coverage area of ​​the eNB: PC5-based V2V and Uu-based V2V (refer to Non-Patent Literature 24 (TR36.885V14.0.0)). Figure 41 and Figure 42 This is a conceptual diagram used to illustrate PC5-based V2V and Uu-based V2V. Figure 41 This is a conceptual diagram of PC5-based V2V. In PC5-based V2V, communication is conducted directly between V2V UE (UE#1) and V2V UE (UE#2, UE#3, UE#4) using SL5102.

[0680] Figure 42 This is a conceptual diagram of a Uu-based V2V system. In a Uu-based V2V system, communication occurs directly between V2V UEs (UE#1, UE#2, UE#3, UE#4) via eNB5103. Communication from V2V UE (UE#1) to eNB5103 is performed using UL5104. Communication from eNB5103 to V2V UEs (UE#2, UE#3, UE#4) is performed using DL5105.

[0681] V2X communication, including V2V (vehicle-to-vehicle) communication, is used for autonomous driving. It is assumed to be used for safety measures such as avoiding collisions between vehicles at intersections, avoiding collisions with vehicles braking suddenly or stopping abruptly, and avoiding collisions with pedestrians or bicycles. Therefore, high reliability is required for V2X communication.

[0682] To improve reliability in V2V communication, a CA-based packet replication method for PC5 in 3GP was explored (refer to Non-Patent Document 25 (R2-1708062)). This method involves performing CA (Carrier Aggregation) in SL and using different component carriers to transmit data replicated in PDCP.

[0683] In PC5's CA-based packet replication, for example, in situations where there are obstacles between V2V UEs, even with multiple carriers in carrier aggregation, communication quality will degrade regardless of which carrier is used. Even under such circumstances, packet replication cannot receive data transmitted using different component carriers. Therefore, in PC5's CA-based packet replication, problems such as degraded reliability of V2V communication sometimes arise.

[0684] In this 6th embodiment, a method for solving the above-mentioned problems is disclosed.

[0685] Packet replication is performed using PC5-based V2V communication and Uu-based V2V communication. Figure 43 This describes packet replication using PC5-based V2V and Uu-based V2V. For V2V, the UE (UE#1) replicates the transmitted data, sending a replicated set of data directly to the V2V UEs (UE#2, UE#3, UE#4) using the SL5203.

[0686] The V2V UE (UE#1) sends another set of data to the V2V UEs (UE#2, UE#3, UE#4) via the eNB5201. Communication from the V2V UE (UE#1) to the eNB5201 is performed using the UL5202. Communication from the eNB5201 to the V2V UEs (UE#2, UE#3, UE#4) is performed using the DL5204.

[0687] Detailed methods for implementing packet replication in PC5-based V2V and Uu-based V2V are disclosed. The transmitting UE in V2V communication is designated as UE_tx, and the receiving UE is designated as UE_rx. The protocol stacks for PC5 and Uu are configured on UE_tx.

[0688] Packet replication is performed at the upper layer of PDCP in UE_tx. One set of replicated data is sent to UE_rx via the PC5 protocol stack. The other set of data is sent to the eNB via the Uu protocol stack.

[0689] Figure 44 This diagram represents packet replication in UE_tx. UE_tx consists of the application layer, IP layer, layers used by PC5 (PDCP, RLC, MAC, PHY), and layers used by Uu (PDCP, RLC, MAC, PHY). The packet replication function is configured at the upper layer of the PDCP used by PC5 and the PDCP used by Uu. The layer used for packet replication can be configured. Alternatively, packet replication can be performed at the PI layer. Or, packet replication can be performed at the application layer.

[0690] UE_tx replicates data at the packet replication layer, sending one set of data to UE_tx via the PC5 protocol stack and another set of data to eNB via the Uu protocol stack.

[0691] The eNB transmits the duplicated data received from UE_tx from the receiving side to the transmitting side at the PDCP upper layer, and then sends it to UE_rx. UE_rx checks whether the duplicated data received from the eNB is duplicated at the PDCP upper layer. If duplicates are found, the duplicated data is discarded.

[0692] Therefore, packet replication can be performed using PC5-based V2V communication and Uu-based V2V communication.

[0693] If the received data is for V2X purposes, the eNB terminates the received data at the eNB; if the received data is for V2V purposes, the received data is transmitted from the receiving side to the sending side. A method for determining whether the data received by the eNB is for V2X or V2V purposes is disclosed.

[0694] In the UE_tx, information indicating whether the data transmitted via Uu is for V2V or V2X is provided. For example, information indicating that V2V data is V2V data can be provided. Alternatively, information indicating that V2X data is V2X data can also be provided in the UE_tx. Or, both of the above can be used.

[0695] Information indicating whether data is for V2V or V2X use can be provided at the packet replication layer. This offers higher affinity to packet replication and facilitates control. Alternatively, this information can be provided at the IP or application layer. Alternatively, this information can be provided at the layer that determines whether the data is for V2X or V2V use.

[0696] As another method, information indicating whether a UE_tx is used for V2V or V2X can be provided via Uu's PDCP. This is effective for determining whether a UE_tx's AS (access stratum) is used for V2V or V2X. For example, it is effective when performing auxiliary replication on the UE_tx's AS.

[0697] The eNB receiving data from the UE_tx via Uu uses information indicating whether the received data is for V2V or V2X transmission to determine whether it is for V2X or V2V purposes. This determination can be performed at the upper layer of PDCP. If the received data is for V2X purposes, the eNB terminates the reception; if the received data is for V2V purposes, it transmits the data from the receiving side to the sending side. This avoids the problem of not understanding whether the data received by the eNB from the UE_tx via Uu is for V2V or V2X purposes.

[0698] The eNB can transmit data received from the UE_tx via Uu from the receiving side to the transmitting side at either the IP layer or the application layer. For example, if packet replication is implemented at the IP layer for UE_tx, the eNB can transmit the received data from the receiving side to the transmitting side at its own IP layer. Alternatively, if packet replication is implemented at the application layer for UE_tx, the eNB can transmit the received data from the receiving side to the transmitting side at its own application layer.

[0699] When data is transmitted from the receiving side to the sending side in cases where the eNB transmits data from the receiving side to the sending side at the IP layer or application layer, it can cause a change in the IP packet data sequence number (SN). If the SN changes, the UE_rx becomes unable to detect duplicate data in the V2V data received from the eNB. A method to resolve this problem is disclosed.

[0700] UE_tx provides a dedicated SN for V2V transmission data. In addition to the SN provided for regular IP packet data, UE_tx also provides a dedicated SN for V2V transmission data. UE_tx provides a dedicated SN for V2V transmission data at the IP layer or application layer, provides an IP packet data SN for data with a dedicated SN for V2V transmission data, and transmits data with both a dedicated SN for V2V transmission data and an IP packet data SN.

[0701] When the eNB receives V2V data from the UE_tx, it transmits the data, which includes a dedicated SN for V2V transmission data, from the receiving side to the transmitting side at the IP layer or application layer. The UE_rx identifies the SN at the IP layer or application layer based on the data received from the eNB that includes the dedicated SN for V2V transmission data.

[0702] Additionally, UE_rx identifies the V2V transmission data-specific SN sent from UE_tx using SL to provide V2V data. UE_rx uses both the V2V transmission data-specific SN received from the eNB and the V2V transmission data-specific SN received from UE_tx to detect duplicate V2V data. Duplicate data is discarded.

[0703] Therefore, even if the SN of the IP packet data changes when V2V data is transmitted from the receiving side to the sending side in the eNB, UE_rx can still detect the duplication of V2V data sent from UE_tx.

[0704] Figure 45 This is a diagram illustrating an example of packet replication using PC5-based V2V communication and Uu-based V2V communication. Figure 45 An example of setting up a packet replication layer (which can be a protocol) with packet replication functionality at the upper layer of PDCP for UE_tx is disclosed. UE_tx performs packet replication by providing information indicating whether the V2V data is for V2V or V2X purposes at the packet replication layer.

[0705] One set of copied data packets is input to the PC5's PDCP, processed by the RLC, MAC, and PHY, and then sent to the UE_rx. The other set of copied data packets is input to the Uu's PDCP, processed by the RLC, MAC, and PHY, and then sent to the eNB.

[0706] After implementing packet replication at the packet replication layer, information indicating whether the data sent via Uu is for V2V or V2X purposes can be provided. The eNB can then determine whether the data is for V2V or V2X purposes. Alternatively, information indicating whether the data sent via PC5 is for V2V or V2X purposes can be omitted, thus reducing data overhead.

[0707] The eNB receives V2V data sent from the UE_tx and processes this data using the receiving-side PHY, MAC, RLC, and PDCP. The eNB detects duplicate packets and transmits them from the receiving side to the sending side of the data output from the receiving-side PDCP. The detection and transmission of duplicate packets are implemented at the upper layer of PDCP. Here, the layer (which can be a protocol) used for duplicate packet detection / transmission processing is set.

[0708] The eNB uses information provided to the PDCP-output data to determine whether the data is for V2V or V2X purposes. If the received data is for V2X purposes, the eNB transmits the data to the core network, where IP and application layer processing is performed to obtain the V2X data. If the received data is for V2V purposes, the eNB transmits the data from the receiving side to the sending side.

[0709] When transmitting to the sending side, information indicating whether it is for V2V or V2X can be provided directly. Alternatively, this information can be removed. Removing it reduces the overhead of data transmission from the eNB to the UE_rx.

[0710] In the eNB, V2V data transmitted from the receiving side to the transmitting side is input to the PDCP on the transmitting side, processed in RLC, MAC, and PHY, and then sent to UE_rx. UE_rx receives V2V data sent from the eNB and processes the received data in PHY, MAC, RLC, and PDCP.

[0711] On the other hand, UE_rx receives V2V data sent from UE_tx and processes the received data using PHY, MAC, RLC, and PDCP.

[0712] UE_rx performs duplicate data detection and discarding on the data output from these PDCPs. The duplicate data detection and discarding processes are implemented at the higher layer of PDCP. Here, the layer (which can be a protocol) used for duplicate data detection / transmission processing is set.

[0713] UE_rx can use the SN provided at the IP layer to detect duplicate data. If UE_rx receives data with the same SN, it discards subsequently received data. The period for detecting whether data with the same SN has been received can be set. It checks for data with the same SN within a specified period from the first reception. The specified period can be notified to UE_rx in advance by the eNB, or it can be predetermined using standards, etc. Therefore, it is not necessary to constantly retain the first received data, reducing the buffer capacity used for data retention.

[0714] The detection and disposal of duplicate data in UE_rx can be implemented at the IP layer or the application layer. If the IP layer provides a serial number (SN) for IP packet data, then performing this detection and disposal at the IP layer makes the process easier.

[0715] The detection / transmission function for copied data can be configured on the eNB, but it can also be configured on the core network side. By configuring the detection / transmission function for copied data on the eNB, the transmission time from the receiving side to the transmitting side can be shortened. This can reduce the latency of Uu-based V2V communication. In NR, it is supported to separate the base station gNB into CU (Central Unit) and DU (Distributed Unit). The detection / transmission function for copied data can be configured on the CU, achieving the same effect.

[0716] The PC5 resource pool and Uu bearer configuration can be set for packet replication. These configurations can be implemented in advance before packet replication begins. Alternatively, packet replication can be set as a trigger to implement the PC5 resource pool and Uu bearer configurations. These configurations can be implemented using the QoS (QCI) of the data service used for packet replication.

[0717] Figure 46 and Figure 47 This is a diagram illustrating an example of a sequence of bearer settings used for grouped replication. Figure 46 and Figure 47They are connected at the boundary line BL4647. In step ST5502, UE_tx decides whether to perform packet replication. V2V communication can be performed before deciding on packet replication, or it can be omitted. Here, in step ST5501, V2V communication on PC5 is performed between UE_tx and UE_rx.

[0718] The decision to implement packet replication can be made, for example, when the QoS of the communication data does not meet the specified value, or when the QoS required by the communication data is above the specified value.

[0719] QoS metrics can be, for example, metrics representing reliability. A reliability metric could be the receive error rate. QoS metrics can also be metrics representing latency characteristics, such as latency time. QoS metrics can also be metrics representing communication speed. QoS metrics can also be metrics representing bit rate.

[0720] Therefore, only in PC5 V2V communication, when the desired QoS cannot be achieved, packet replication can be decided. The desired QoS can be achieved through packet replication.

[0721] Additionally, UE_tx can use the resource load for SL communication to determine whether to perform packet replication. The resource load for SL communication can be determined using usage or margin, priority of SL communication with other UEs, etc. If the load is low, and sufficient resources cannot be guaranteed for communication, it may be decided to implement Uu-based packet replication. UE_tx can pre-determine the resource load for SL communication.

[0722] In step ST5502, the UE_tx that decides to implement packet replication notifies the eNB of a packet replication configuration request in step ST5503. This request may include information such as bearer identifier, QoS metrics, and SL resource load. The request may also include information indicating that it is for packet replication. QoS metrics can be the information described above. This request can be notified using RRC signaling or MAC signaling. Alternatively, the request can be included in the UCI and notified using PUCCH.

[0723] In step ST5504, resource settings for PC5, used for packet copying of V2V communication data, are performed between the eNB and UE_tx. For example, the eNB notifies the UE of the carrier frequency, resource pool, PSCCH resource settings, and resource application information used for PC5. This information can be communicated using RRC signaling or MAC signaling. Alternatively, this information can be included in the DCI and communicated via PDCCH. When using RRC signaling, RRC connection reconfiguration (RRCConnectionReconfiguration), which is a known RRC message, can be used. No new configuration message is required, allowing for easy control.

[0724] In step ST5505, bearer configuration on the Uu for packet copying of V2V communication data is performed between the eNB and UE_tx. The eNB performs communication configuration on the Uu for the UE. For example, settings such as the frequency used by the UL can be implemented. This configuration can be notified using RRC signaling or MAC signaling. Alternatively, the configuration can be included in the DCI and notified using PDCCH. When using RRC signaling, RRC connection reconfiguration (RRCConnectionReconfiguration) can be used as a known RRC message. No new configuration message is required, making it easy to control.

[0725] In step ST5506, bearer configuration on the Uu for packet replication of V2V communication data is performed between the eNB and UE_rx. The eNB performs communication configuration on the Uu for the UE. For example, MBMS communication or SC-PTM communication configuration can be implemented for DL. This configuration can be notified using RRC signaling or MAC signaling. Alternatively, the configuration can be included in the DCI and notified using PDCCH.

[0726] When configuring MBMS or SC-PTM communication, the eNB can configure the bearer for MBMS or SC-PTM communication with the core network side.

[0727] In step ST5507, UE_tx, which performs packet replication of V2V communication data using PC5 resource settings and Uu bearer settings, begins packet replication. UE_tx performs data replication at the packet replication layer. In step ST5508, one set of replicated data is sent to UE_rx via PC5, and in step ST5509, another set of replicated data is sent to the eNB via Uu.

[0728] In step ST5510, the eNB uses information indicating whether the data received from UE_tx is for V2V communication to detect whether it is V2V communication data at the copy packet detection / transport layer. If it is V2V communication data, the eNB transmits the data from the receiving side to the transmitting side. In step ST5511, the eNB sends the transmitted copy data to UE_rx.

[0729] The communication in steps ST5508, ST5509, and ST5511 can be implemented using the settings in steps ST5504, ST5505, and ST5506.

[0730] In step ST5512, UE_rx, at the layer for duplicate data detection / discarding, uses the SN provided at the IP layer to detect whether the data received from the eNB and the data received from UE_tx are duplicates. If duplicates are found, the subsequently received data is discarded in step ST5513. The first received data and the non-duplicate data are sent to the IP layer or application layer.

[0731] Therefore, UE_rx can receive V2V communication data that is packet-replicated in UE_tx.

[0732] The UE_tx can determine whether to terminate packet replication. For example, it can use the QoS (Quality of Service) for communication data or the load of resources used for SL (Single-Level Communication) to determine whether to terminate packet replication. For instance, if the QoS for communication data meets a specified value, it can be determined to terminate packet replication. Conversely, if the load of resources used for SL communication is below a specified value, it can be determined to terminate packet replication.

[0733] Therefore, group replication can be terminated when it is not needed. Group replication requires resources from both PC5 and Uu. By terminating group replication, unnecessary resource usage can be reduced.

[0734] A separate bearer can be configured for V2V communication. Packet replication can be performed using this V2V communication bearer. Furthermore, when a separate bearer is configured for packet replication of V2V communication data, the channel and / or channel group used for packet replication can be different from the channel and / or channel group used for other communications. Dedicated channels and / or channel groups for packet replication can be configured. QoS-appropriate processing can be implemented.

[0735] The pre-configured resource settings of PC5 and bearer settings of Uu can be used for packet replication of V2V communication data. Steps ST5504, ST5505, and ST5506 can be omitted. This reduces the time spent on PC5 resource configuration processing and Uu bearer configuration processing, and lowers the latency from deciding to replicate packets to implementing the replication.

[0736] A portion of the pre-configured PC5 resource settings and pre-configured Uu bearer settings can be used for packet replication of V2V communication data. For example, the Uu settings from the eNB to the UE_rx use known resource settings for MBMS or SC-PTM bearers. In addition to these settings, new settings are also performed. Since the Uu settings from the eNB to the UE_rx use resource settings for MBMS or SC-PTM, they require bearer settings from the core network. Therefore, the configuration is particularly time-consuming. By reducing this time, the latency from deciding to replicate packets to implementing packet replication can be reduced.

[0737] The method disclosed above determines whether UE_tx is implementing packet replication. Alternatively, it can determine whether the eNB is implementing packet replication. The eNB that decides to implement packet replication notifies UE_tx of the implementation (activation) of packet replication. The activation of packet replication may include information about which bearer's packet replication is activated. This information could, for example, be a bearer identifier.

[0738] This notification can be sent using RRC signaling. It can send large amounts of information. It can also be sent using MAC signaling or PDCCH. It allows for dynamic notification. In the case of MAC signaling, it reduces false alarms.

[0739] Upon receiving activation for packet replication from the eNB, the UE_tx implements packet replication. A UE_tx that has completed packet replication configuration can report that the configuration is complete. This report can be sent using RRC signaling, MAC signaling, or PUCCH.

[0740] The method disclosed above determines whether UE_tx has ended packet replication. Alternatively, it can determine whether the eNB has ended packet replication. The eNB that decides to end packet replication notifies UE_tx of the end of packet replication (deactivation). The deactivation of packet replication can include information about which bearer's packet replication is deactivated. This information can be, for example, a bearer identifier.

[0741] This notification can be sent using RRC signaling. It can send large amounts of information. It can also be sent using MAC signaling or PDCCH. It allows for dynamic notification. In the case of MAC signaling, it reduces false alarms.

[0742] The eNB uses RRC signaling to notify the UE_tx of packet replication settings and resets, and uses MAC signaling or PDCCH to notify the activation or deactivation of packet replication. These settings can be pre-configured and dynamically adjusted for activation or deactivation.

[0743] UE_tx can notify the eNB of a packet replication activation request. Upon receiving this request, the eNB determines whether to activate packet replication. If the eNB decides to activate, it notifies UE_tx of packet replication activation. If the eNB decides not to activate, it notifies UE_tx of a packet replication rejection message. The rejection message can contain a reason for not activating. Such a reason could be, for example, insufficient inter-UE resources.

[0744] Similarly, UE_tx can notify the eNB of a request to terminate packet replication. Upon receiving this request, the eNB determines whether to terminate packet replication. If the eNB decides to terminate, it notifies UE_tx of packet replication deactivation. If the eNB decides not to terminate, it notifies UE_tx of a rejection message. The rejection message can contain a reason for not terminating. Such a reason could be, for example, the availability of resources between UEs. By allowing packet replication to continue, low latency characteristics can be achieved, thus aiming to further improve throughput.

[0745] The packet replication request notified by the UE_tx to the eNB can include information such as the bearer identifier requesting packet replication, the QPS metric, and the load of SL resources. It can also notify the UE_tx of the QoS or SL resource load as measured. The eNB can use this information to determine whether to implement packet replication.

[0746] Furthermore, the eNB can use information related to itself or information related to the Uu's resources to determine whether to implement packet copying. Information related to the eNB itself includes its processing power, CPU usage, and buffer usage. Information related to the Uu's resources includes the UL's resource usage and the subframe usage in the DL's MBSFN. Therefore, by using information from the eNB, the eNB's status or the radio wave transmission environment or load in the Uu can be considered when making this decision.

[0747] UE_tx can use the request to implement packet replication of eNB notifications. Figure 46 and Figure 47 The packet replication setting request disclosed herein (step ST5503) may include information indicating that it is a packet replication implementation request. Additionally, the eNB can use the packet replication activation notification from the UE_tx to respond to the UE_tx notification. Figure 46 and Figure 47 The PC5 resource settings for packet replication (step ST5504) or the Uu bearer settings for packet replication (step ST5505) disclosed herein may contain information indicating that packet replication is active.

[0748] eNB can also notify Ue_rx whether group replication is activated or deactivated. This can be used... Figure 46 and Figure 47 The group replication configuration on the Uu server disclosed in the document is set up (step ST5506).

[0749] By adopting the method disclosed in Embodiment 6, packet replication can be performed using PC5-based V2V communication and Uu-based V2V communication. Unlike CA-based packet replication, other nodes, such as eNBs, can be used for packet replication. Therefore, for example, even in situations where obstacles arise between V2Vs, or where the quality of SL communication between V2Vs deteriorates regardless of the carrier frequency, packet replication using other nodes can be implemented. Thus, the high reliability required for V2V communication can be obtained.

[0750] Furthermore, in CA-based packet replication, terminals that do not support CA cannot apply packet replication. However, by adopting the method disclosed in Embodiment 6, packet replication can be implemented even for terminals that do not support CA. Therefore, the high reliability required in V2V communication can be achieved.

[0751] Furthermore, in PC5-based V2V communication, if the communication quality of SL deteriorates, packet data retransmission occurs, sometimes increasing latency. By adopting the method disclosed in Embodiment 6, packet data communication can be performed using Uu-based V2V communication even when latency occurs in PC5-based V2V communication, thus reducing communication latency.

[0752] In NR base stations (gNB) or LTE base stations connected to the 5G core network, and in UEs connected to these base stations, SDAP is configured at the upper layer of PDCP. When SDAP is configured, packet replication can also be implemented at the SDAP or its upper layer. Packet replication in the PDU session is implemented. In such cases, the method disclosed in Embodiment 6, which provides information indicating whether it is for V2V or V2X use, can also be applied.

[0753] In NR base stations (gNB) or LTE base stations connected to the 5G core network, V2V communication data from UE_tx can be detected and transmitted to UE_rx. These functions can be implemented in SDAP or its upper-level layer. Additionally, duplicate packet detection and discarding can be performed in UE_rx or its upper-level layer within SDAP.

[0754] Therefore, V2V communication can be performed in NR base stations (gNB) or LTE base stations connected to the 5G core network, and in UEs connected to the base station. Packet replication can be performed using PC5-based V2V communication and Uu-based V2V communication.

[0755] The information disclosed details the UE_tx notification packet replication setting request to the eNB. When the UE_tx is connected to a base station (gNB) in NR or to a base station in LTE connected to the 5G core network, the UE_tx can notify the base station of the PDU session identifier and QoS procedure identifier.

[0756] Additionally, the activation and deactivation of packet replication notifications from the eNB to the UE_tx are disclosed. The activation or deactivation notification of packet replication from the UE_tx base station (gNB) in the NR or the LTE base station connected to the 5G core network can include the PDU session identifier and the QoS procedure identifier.

[0757] Therefore, even when packet replication is implemented for PDU sessions or QoS procedures, the PDU session or QoS procedure implementing packet replication can be identified.

[0758] Variation 1 of Implementation Method 6.

[0759] Other methods for resolving the problems shown in Implementation 6 are disclosed. Group copying is performed at the PDCP layer of UE_tx. Group copying can be performed at the PDCP layer used by PC5. The function of group copying is set at the PDCP layer of UE_tx. The function of group copying can be set at the PDCP layer used by PC5.

[0760] Figure 48 This is a diagram illustrating an example of packet replication using PC5-based V2V communication and Uu-based V2V communication. Figure 48 The functionality of setting up group replication at the PDCP layer of UE_tx has been disclosed.

[0761] Packet replication is performed via the PDCP used by PC5 in UE_tx. One set of replicated data is sent to UE_rx through the PC5 protocol stack. Another set of data is input to the PDCP layer of Uu and sent to the eNB through the Uu protocol stack. When the replicated data is input to the PDCP of Uu, it can be input to the PDCP used by Uu as a PDCP SDU.

[0762] The eNB transmits the duplicated data received from UE_tx from the receiving side to the transmitting side at the PDCP layer or the upper layer of PDCP, and then sends it to UE_rx. UE_rx detects the duplicated data received from the eNB at the PDCP layer of UE_tx or the upper layer of PDCP, and transmits it to the PDCP layer of PC5. UE_rx checks for data duplication at the PDCP layer of PC5; if duplicates are found, the duplicated data is discarded.

[0763] Therefore, packet replication can be performed using PC5-based V2V communication and Uu-based V2V communication.

[0764] When the received data is for V2X purposes, the eNB terminates the received data at the eNB; when the received data is for V2V purposes, the received data is transmitted from the receiving side to the sending side. A method for determining whether the data received by the eNB is for V2X or V2V purposes is disclosed.

[0765] In the PC5 PDCP of UE_tx, information indicating that the data is being transmitted via V2V is provided. The SN (Sequence Number) of the PC5 PDCP can be provided in the same way as before. Hiding processing can be performed in the PC5 PDCP in the same way as before.

[0766] Packet replication can be implemented after the SN provision and concealment processes are implemented. The provision of information indicating V2V transmission data can be implemented after packet replication in the PC5's PDCP. This information provision can be implemented only as data input to the Uu's PDCP layer. Data communicated in the PC5 uses the same data format as existing data, thus allowing for easy control. Data providing information indicating V2V transmission data is input to the Uu's PDCP layer as a PDCP SDU.

[0767] The eNB receiving data from the UE_tx via Uu uses information indicating whether the received data is for V2V transmission to determine whether it is for V2X or V2V transmission. This determination can be performed at the PDCP layer or a higher layer than PDCP. If the received data is for V2X, the eNB terminates the reception; if the received data is for V2V, it transmits the data from the receiving side to the transmitting side. This avoids the problem of not knowing whether the data received by the eNB from the UE_tx via Uu is for V2V or V2X transmission.

[0768] When the eNB identifies hidden information, such as a hidden key, used for PC5 communication in UE_tx, the processing indicating that the data is for V2V transmission in UE_tx can be performed before the hidden processing is implemented. The eNB uses the hidden information for PC5 communication to release the data sent from UE_tx via Uu, and uses the information indicating that the data is for V2V transmission to determine whether the data is for V2X or V2V. This determination is better performed at the upper layer of PDCP. By separating the PDCP function of the receiving side Uu of the eNB, multiple hidden release processes are eliminated from the PDCP. Therefore, malfunctions under this PDCP can be reduced.

[0769] The eNB can notify the UE_tx in advance of hidden information used for PC5 communication. The eNB can include this hidden information in the PC5 resource settings for notification. Alternatively, if the UE_tx decides on the hidden information to use for PC5, the UE_tx will notify the eNB in ​​advance of the hidden information used for PC5 communication.

[0770] This avoids the problem of not understanding whether the data received by the eNB from the UE_tx via Uu is for V2V or V2X purposes.

[0771] Regarding data received from the eNB, UE_rx uses information indicating that it is V2V transmission data provided for the received data to determine whether the data is packet-copying data. This determination can be performed at the PDCP layer of the Uu. Alternatively, this determination can be performed at a higher layer of PDCP. After the PDCP processing of the Uu between the eNB and UE_rx is completed, this determination can be performed using information indicating that it is V2V transmission data provided for the received data.

[0772] If UE_rx determines that the data received from the eNB is packet-copyable data, it will input the data processed at the end of PDCP in Uu to the PDCP layer of PC5. PC5's PDCP releases the hidden processing performed in UE_tx's PDCP and uses the PDCP SN to detect duplicates between V2V transmission data sent from the eNB and V2V transmission data sent from UE_tx via PC5. Duplicate data is discarded. No duplicate data is sent to the upper layer.

[0773] Figure 49 and Figure 50 This is a diagram of Embodiment 1 of Implementation 6, showing an example of a sequence of bearer settings for grouped replication. Figure 49 and Figure 50 Connect at the boundary line BL4950. Figure 49 and Figure 50 In this configuration, the pre-defined resource settings for PC5 and the bearer settings for Uu are used for group replication. For the bearer settings for Uu, known V2X bearer settings can be used.

[0774] In step ST5701, V2V communication over PC5 is performed between UE_tx and UE_rx. In step ST5702, V2X communication over Uu is performed between UE_tx and eNB. In step ST5713, V2X communication over Uu is performed between eNB and UE_rx.

[0775] In step ST5703, UE_tx decides whether to perform packet replication. The method for deciding whether to perform packet replication can be the method disclosed in Embodiment 6. The eNB can also decide whether to perform packet replication. The method disclosed in Embodiment 6 can be applied. UE_tx, which decides to perform packet replication in step ST5703, begins packet replication in step ST5704. UE_tx performs data replication at the PDCP layer of PC5, providing information indicating that the data is for V2V transmission. This information can be provided only for data transmitted to the eNB via Uu. In step ST5705, one set of replicated data is sent to UE_rx via PC5, and in step ST5706, another set of replicated data is sent to the eNB via Uu.

[0776] In step ST5707, the eNB performs duplicate packet detection / transmission on the data received from UE_tx at the PDCP layer or a layer higher than PDCP. The eNB uses information indicating whether the data received from UE_tx is for V2V communication to detect whether it is V2V communication data. If it is V2V communication data, the eNB transmits the data from the receiving side to the transmitting side. In step ST5708, the eNB sends the transmitted duplicate data to UE_rx.

[0777] The communication in steps ST5705, ST5706, and ST5708 can be implemented using the resource settings of PC5 and the bearer settings of Uu used in steps ST5701, ST5702, and ST5713.

[0778] In step ST5709, UE_rx performs duplicate packet detection. This detection is performed at the PDCP layer or a layer higher than PDCP. UE_rx uses information indicating that the data is being transmitted for V2V purposes to detect whether the data received from the eNB is duplicate data. If it is duplicate data, it is transmitted to the PDCP layer of PC5 in step ST5710. If UE_rx determines in step ST5709 that the data is not duplicate data, it sends the data to the IP layer and application layer.

[0779] UE_rx performs duplicate data detection / discarding processing in PC5's PDCP. In step ST5711, UE_rx uses the SN provided by the PDCP layer of UE_tx to detect whether the data transmitted from the Uu side and the data received from UE_tx are duplicates. If duplicates are found, the subsequently received data is discarded in step ST5712. The previously received data and the non-duplicate data are sent to the IP layer or application layer.

[0780] Therefore, UE_rx can receive V2V communication data that is packet-replicated in UE_tx.

[0781] The UE_tx can decide whether to terminate packet replication. The method for making this decision can be the one disclosed in Implementation 6. The eNB can also decide whether to terminate packet replication. The method disclosed in Implementation 6 can be applied.

[0782] By using the method disclosed in this variation 1, which is embodiment 6, the same effects as those shown in embodiment 6 can be obtained. Furthermore, since packet duplication is performed in the PDCP, it is possible to determine whether the data is for V2V communication in the RAN, such as the eNB. Additionally, since packet duplication is performed in the PDCP, duplicate data detection processing, duplicate data detection processing, and discard processing can be performed in the PDCP of the UE_rx.

[0783] Furthermore, since determining whether data is used for V2V communication within the base station does not require application layer or IP layer processing, the detection and transmission of V2V communication data can be performed earlier at the base station. This reduces the latency of Uu-based V2V communication. Therefore, packet replication using both PC5-based and Uu-based V2V communication can be implemented with low latency, improving reliability and throughput.

[0784] Furthermore, since the packet replication decision can be determined within the AS of UE_tx, no involvement from the upper layer is required. The AS of UE_tx often obtains indicators used by UE_tx to determine packet replication. Therefore, the packet replication decision of UE_tx can be determined earlier, allowing for rapid response to temporal changes in the radio wave propagation environment of SL.

[0785] Furthermore, in the method disclosed in Modification 1 of Embodiment 6, in order to perform packet replication in PDCP, the method disclosed in Modification 1 of Embodiment 6 can also be applied to packet replication using V2V communication via a base station (gNB) in NR or a base station in LTE connected to a 5G core network. The same effects as described above can be obtained.

[0786] Variation 2 of Implementation Method 6.

[0787] Other methods for resolving the problem shown in Implementation 6 are disclosed. Grouped replication is performed at the PDCP layer of PC5 in UE_tx, causing the replicated data to be forked between PC5 and Uu. A forked bearer can be set between PC5 and Uu.

[0788] Figure 51 This is a diagram illustrating an example of packet replication using PC5-based V2V communication and Uu-based V2V communication. Figure 51 The function of setting up group replication in the PDCP layer of PC5 of UE_tx is disclosed, and the case of fork between PC5 and Uu is disclosed.

[0789] In UE_tx, packet replication is performed using PDCP on PC5, and the replicated data is forked. One forked set of data is sent to UE_rx via the PC5 protocol stack. The other forked set of data is input to the RLC layer of Uu and sent to the eNB via the Uu protocol stack. When the forked replicated data is input to Uu's RLC, it can be used as an RLC SDU.

[0790] The eNB transmits the duplicated data received from UE_tx from the receiving side to the transmitting side at the RLC layer, and then sends it to UE_rx. UE_rx detects the duplicated data received from the eNB at the RLC layer of Uu and transmits it to the PDCP layer of PC5. UE_rx checks for data duplication at the PDCP layer of PC5, and discards the duplicated data if duplicates are found.

[0791] Therefore, packet replication can be performed using PC5-based V2V communication and Uu-based V2V communication.

[0792] If the data received from the UE_tx is for V2X purposes, the eNB terminates the received data at the eNB level; if the received data is for V2V purposes, the eNB transmits the received data from the receiving side to the transmitting side at the RLC layer. A method for determining whether the data received by the eNB is for V2X or V2V purposes is disclosed.

[0793] A forked bearer can be configured between PC5 and Uu. This forked bearer is configured for parallel execution of a first communication directly connecting PC5 of UE_tx to PC5 of UE_rx, and a second communication connecting PC5 of UE_tx via Uu of UE_tx, the Rx and Tx sides of Uu of eNB, and Uu of UE_tx to PC5 of UE_tx. The forked bearer is configured, and the channels and / or channel groups used for communication using the forked bearer are different from those used for other communications. Dedicated channels and / or channel groups can be configured for communication using the forked bearer.

[0794] In forked bearer, the SN provisioning and hiding process can be performed in the PC5 PDCP of UE_tx in the same way as before. After performing the SN provisioning and hiding process in the PC5 PDCP of UE_tx in the same way as before, packet replication can be performed, and the packet-replicated data can be forked and input to the RLC of PC5 and Uu.

[0795] Therefore, by setting up a forked bearer, communication using the forked bearer is separated from other communication. Thus, at the RLC layer on the receiving side of the eNB's Uu, it can be determined whether the data received by the eNB is for V2V purposes.

[0796] The eNB will transmit V2V data from the receiving side to the transmitting side at the RLC layer in the designated fork bearer to the UE_rx. The UE_rx will process the data received from the eNB up to the RLC layer in the designated fork bearer, and then transmit the RLC-processed data to the PDCP of the PC5.

[0797] Therefore, the forked bearer is also set between the eNB and UE_rx, and communication using the forked bearer is separated from other communication in UE_rx. Thus, at the RLC layer on the Uu receiving side of UE_rx, it can determine whether the data received from the eNB is data that was packet-copied in the PDCP of PC5 in UE_tx.

[0798] The PDCP release of PC5 in UE_rx is hidden in the PDCP of UE_tx, and the PDCP SN is used to detect duplicates between V2V transmission data sent from the eNB and V2V transmission data sent from UE_tx via PC5. Duplicate data is discarded. No duplicate data is sent to the upper layer.

[0799] Alternatively, UE_tx can provide information indicating V2V communication at the input of Uu's RLC (RLC SDU) or the output of PC5's PDCP (PDCPPDU). The eNB uses this V2V communication information to determine whether the data is intended for V2V communication at the receiving side's Uu's RLC or between the RLC and PDCP. Furthermore, this also allows determination, even within UE_rx, at Uu's RLC or between the RLC and PDCP, whether the data is packet-copyable data.

[0800] Figure 52 and Figure 53 This is a diagram of embodiment 2 of implementation 6, showing an example of a sequence for setting a fork bearer. Figure 52 and Figure 53 Connect at the boundary line BL5253. Use the defined fork bearer to implement grouped replication.

[0801] In step ST5901, V2V communication over PC5 is performed between UE_tx and UE_rx. In step ST5902, UE_tx decides whether to implement packet replication. The method for deciding whether to implement packet replication can be the method disclosed in Embodiment 6. The eNB can decide whether to implement packet replication. The method disclosed in Embodiment 6 can be applied.

[0802] In step ST5902, the UE_tx that decides to implement packet replication notifies the eNB of a forked bearer configuration request in step ST5903. This request may include information such as bearer identifier, QoS metrics, and SL resource load. The QoS metrics can be information as described above. This request can be notified using RRC signaling or MAC signaling. Alternatively, the request can be included in the UCI and notified using PUCCH.

[0803] In step ST5904, a forked bearer configuration is implemented on Uu between the eNB and UE_tx. This configuration can be communicated using RRC signaling or MAC signaling. Alternatively, the configuration can be included in the DCI and communicated via PDCCH. When using RRC signaling, RRC Connection Reconfiguration, which is a known RRC message, can be used. No new configuration message is required, allowing for easy control.

[0804] In step ST5905, a forked bearer configuration is implemented on Uu between the eNB and UE_rx. For example, MBMS communication or SC-PTM communication configuration can be implemented for DL. This configuration can be notified using RRC signaling or MAC signaling. Alternatively, this configuration can be included in the DCI and notified using PDCCH.

[0805] When configuring MBMS or SC-PTM communication, the eNB can configure the bearer for MBMS or SC-PTM communication with the core network side.

[0806] In step ST5906, UE_tx, which has configured fork bearer on Uu, begins packet replication. UE_tx performs data replication at the PDCP layer of PC5, forking the replicated data to the RLC of PC5 and the RLC of Uu. In step ST5907, UE_tx sends one set of replicated data to UE_rx via PC5, and in step ST5908, it sends another set of replicated data to the eNB via Uu.

[0807] In step ST5909, the eNB performs V2V communication packet detection on the data received from UE_tx between the RLC or between the RLC and PDCP. The eNB uses information indicating whether the received data is for V2V communication or V2X communication to check if it is V2V communication data. This detection can be determined by whether the communication uses a forked bearer. If it is V2V communication data, the eNB transmits the data from the receiving RLC of Uu to the transmitting RLC. In step ST5910, the eNB sends a copy of the transmitted data to UE_rx.

[0808] In step ST5911, UE_rx detects whether communication data uses a forked bearer. This detection is determined by whether the data uses a forked bearer. This detection is performed between RLC or between RLC and PDCP. If the data uses a forked bearer, UE_rx transmits it to the PDCP layer of PC5 in step ST5912. If UE_rx determines in step ST5911 that the communication does not use a forked bearer, it sends the data to the IP layer and application layer.

[0809] UE_rx performs duplicate data detection / discarding processing in PC5's PDCP. In step ST5913, UE_rx uses the SN provided by the PDCP layer of UE_tx to detect whether the data transmitted from the Uu side and the data received from UE_tx are duplicates. If duplicates are found, the subsequently received data is discarded in step ST5914. The previously received data and the non-duplicate data are sent to the IP layer or application layer.

[0810] Therefore, UE_rx can receive V2V communication data that is packet-replicated in UE_tx.

[0811] The UE_tx can decide whether to terminate packet replication. The method for making this decision can be the one disclosed in Implementation 6. The eNB can also decide whether to terminate packet replication. The method disclosed in Implementation 6 can be applied.

[0812] By employing the method disclosed in this variation 2 of Embodiment 6, the same effects as those shown in Variation 1 of Embodiment 6 can be obtained. Furthermore, in the eNB, the copied packet data is transmitted from the receiving side to the transmitting side between the RLC or between the RLC and PDCP, thus reducing processing time. This further reduces the latency of PC5-based V2V communication. Therefore, throughput during packet copying operations can be improved.

[0813] Furthermore, existing processing methods can be used for providing and hiding the SN in the PDCP of UE_tx. Therefore, processing in the PDCP of UE_tx can be performed easily. In addition, the occurrence of malfunctions can be reduced.

[0814] Furthermore, in the method disclosed in this variation 2 of Embodiment 6, in order to implement packet replication in PDCP, the method disclosed in this variation 2 of Embodiment 6 can also be applied to packet replication using V2V communication via a base station (gNB) in NR or a base station in LTE connected to a 5G core network. The same effects as described above can be obtained.

[0815] In a base station, V2V communication data can be detected and transmitted at a lower layer than the layer where packet replication occurs. In this case, the UE_tx is disclosed to provide information indicating whether it is for V2V or V2X use, but this information may not be provided. It is sufficient that V2V and V2X use can be identified.

[0816] For example, UE_tx uses different logical channels for V2V and V2X communication. The base station determines at the MAC layer or between the MAC and RLC layers whether to use either the V2V or V2X logical channel, and performs V2V communication data detection and transmission.

[0817] For example, UE_tx pre-defines the logical channels for V2V and V2X communication. Additionally, the base station or UE_tx, corresponding to this logical channel, pre-defines the physical resources for mapped data for V2V and V2X communication. The base station determines at the PHY layer whether the data is mapped to which physical resource (V2V or V2X) and performs V2V data detection and transmission.

[0818] Therefore, by identifying V2V and V2X applications, the detection and transmission of V2V communication data can be implemented at lower layers than the layer performing packet replication, such as RLC, MAC, and PHY. This reduces processing latency in the base station. It also reduces processing latency for Uu-based V2V communication. Thus, packet replication using PC5-based and Uu-based V2V communication can be performed with low latency, improving reliability and throughput.

[0819] By reducing the latency of Uu-based V2V communication, the priority of V2V communication data is improved compared to other communication methods. Furthermore, the reduced latency of Uu-based V2V communication reduces the number of HARQ retransmissions supported by Uu. Additionally, in Uu-based V2V communication, the transmission mode in RLC can be set to a mode without ARQ. Moreover, while the above description specifies V2V communication, it can also be limited to packet replication. Thus, the latency of Uu-based V2V communication or the latency in packet replication can be reduced.

[0820] 3GPP has studied the use of Roadside Units (RSUs) for V2X. RSUs include base station type RSUs with base station functionality and UE type RSUs with UE functionality. In the methods disclosed in Embodiments 6 to 6 Modification 2, the UE can be a UE type RSU. Furthermore, in the methods disclosed in Embodiments 6 to 6 Modification 2, the base station can be a base station type RSU. The same effect can be obtained.

[0821] In V2V communication, a method for connecting a UE and a base station via a UE-type RSU was investigated. For example, UE_tx sends V2V communication data to a UE-type RSU, the UE-type RSU sends V2V communication data to the base station, the base station V2V sends V2V communication data to other UE-type RSUs, and the other UE-type RSUs send V2V communication data to UE_rx.

[0822] In such cases, the methods disclosed in Embodiments 6 to 6 Modification 2 can also be applied. Since the data for V2V communication is detected / transmitted via a UE-type RSU, this function can be applied to the methods disclosed in Embodiments 6 to 6 Modification 2. The detection and transmission of V2V communication data can be implemented at layers suitable for each method.

[0823] Therefore, in V2V communication, V2V communication via RSU of UE type can be performed, and packet replication using PC5-based V2V communication and Uu-based V2V communication can be performed.

[0824] In Variations 1 and 2 of Embodiment 6, packet copying of PC5-based V2V communication data for UE_tx is disclosed. Packet copying can be applied to V2V communication data of Uu based on UE_tx. The methods disclosed in Variations 1 and 2 of Embodiment 6 can be appropriately applied. The same effect can be obtained through packet copying.

[0825] The above-described embodiments and their modifications are merely illustrative of the present invention. Within the scope of the present invention, the embodiments and their modifications can be freely combined. Furthermore, any constituent elements of the embodiments and their modifications can be appropriately modified or omitted.

[0826] For example, in the above embodiments and their variations, a subframe is an example of a communication time unit in a 5G base station communication system. It can also be a scheduling unit. In the above embodiments and their variations, processing for recording in subframe units can be performed according to TTI units, time slot units, sub-time slot units, or micro-time slot units.

[0827] The present invention has been described in detail, but the above description is merely illustrative of all aspects, and the invention is not limited thereto. Numerous variations not illustrated are to be understood without departing from the scope of the invention.

[0828] Label Explanation

[0829] 200 Communication system, 202 Communication terminal device, 203 Base station device.

Claims

1. A user equipment, which is a user equipment in a communication system, the communication system having the user equipment and a plurality of base stations that wirelessly communicate with the user equipment, characterized in that, The multiple base stations include a primary node and a secondary node supporting dual connectivity for the user equipment. During the procedure for adding or changing the secondary node, RRC signaling containing information related to the use of the forked SRB or SRB3 is received from the primary node. When the forked SRB is configured, it is used to send information related to primary cell group faults. If SRB3 is configured but the fork SRB is not configured, SRB3 is used to send information related to the primary cell group fault. In the event of a primary cell group failure, if the forked SRB is configured, the forked SRB is used to receive RRC from the primary node via the secondary node and then reconfigure it.

2. The user equipment as claimed in claim 1, characterized in that, Send a response to the secondary node regarding the resetting of the RRC.

3. A base station, which is one of the base stations in a communication system, the communication system having a user device and a plurality of base stations wirelessly communicating with the user device, characterized in that, The multiple base stations include a primary node and a secondary node supporting dual connectivity for the user equipment. During the procedure for adding or changing the secondary node, RRC signaling containing information related to the use of the forked SRB or SRB3 is sent to the user equipment. When the forked SRB is configured, the base station uses the forked SRB to send information related to primary cell group faults. The base station functions as the primary node that, in the event of a primary cell group failure and with the forked SRB configured, uses the forked SRB to send RRCs via the secondary node and then configures the primary node.

4. A communication system comprising a user device and a plurality of base stations wirelessly communicating with the user device, characterized in that, The multiple base stations include a primary node and a secondary node supporting dual connectivity for the user equipment. During the procedure for adding or changing the secondary node, the user equipment receives RRC signaling from the primary node, including information related to the use of the forked SRB or the use of SRB3. When the forked SRB is configured, the user equipment uses the forked SRB to send information related to primary cell group failures. If SRB3 is configured but the forked SRB is not configured, the user equipment uses SRB3 to send information related to the primary cell group fault. When the user equipment is in a state of primary cell group failure and the forked SRB is set, it uses the forked SRB to receive RRC from the primary node via the secondary node and then re-set it.

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