First communication terminal, second communication terminal, and communication system

Abstract

To provide a communication terminal and a communication system that ensure the QoS required for services, thereby providing good communication.SOLUTION: A communication system 210 comprises a plurality of communication terminals 202 including a first communication terminal and a second communication terminal that perform sidelink communication via a PC5 interface and a network including one or more core network nodes. The one or more core network nodes comprises a session management function (SMF). The first communication terminal is a relay communication terminal that performs relaying between the second communication terminal and the network, establishes a Protocol Data Unit (PDU) session used for relaying between the first communication terminal and the network, and transmits, to the SMF, information on the second communication terminal in a procedure for establishing the PDU session for relaying.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present disclosure relates to wireless communication technology. [Background technology]

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

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

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

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

[0006] The Physical Broadcast Channel (PBCH) is a channel for downlink transmission from a base station (hereinafter simply referred to as a "base station") to a communication terminal (hereinafter simply referred to as a "communication terminal") such as a mobile terminal (hereinafter simply referred to as a "mobile terminal"). A BCH transport block is mapped to four subframes in a 40 ms interval. There is no explicit signaling of the 40 ms timing.

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

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

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

[0010] A physical multicast channel (PMCH) is a channel for downlink transmission from a base station to communication terminals, and a multicast channel (MCH), which is a transport channel, is mapped to the PMCH.

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

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

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

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

[0015] Similarly, the uplink reference signal is a symbol known in LTE communication systems. Two types of uplink reference signals are defined: a data demodulation reference signal (DM-RS) and a sounding reference signal (SRS).

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

[0017] Retransmission control using HARQ (Hybrid ARQ) is applied to the Downlink Shared Channel (DL-SCH). DL-SCH can be broadcast to the entire coverage of a base station (cell). DL-SCH supports dynamic or semi-static resource allocation. Semi-static resource allocation is also called persistent scheduling. DL-SCH supports discontinuous reception (DRX) in communication terminals to reduce power consumption of communication terminals. DL-SCH is mapped to the Physical Downlink Shared Channel (PDSCH).

[0018] The Paging Channel (PCH) supports DRX in communication terminals to enable low power consumption in communication terminals. The PCH is required to broadcast to the entire coverage of the base station (cell). The PCH is mapped to physical resources such as the Physical Downlink Shared Channel (PDSCH) that can be dynamically used for traffic.

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

[0020] Among the uplink transport channels, the Uplink Shared Channel (UL-SCH) is subject to retransmission control using HARQ (Hybrid ARQ). The UL-SCH supports dynamic or semi-static resource allocation. The UL-SCH is mapped to the Physical Uplink Shared Channel (PUSCH).

[0021] The Random Access Channel (RACH) is limited to control information. The RACH is subject to collision risk. The RACH is mapped to the Physical Random Access Channel (PRACH).

[0022] We will explain HARQ. HARQ is a technology that improves the communication quality of a transmission channel by combining Automatic Repeat reQuest (ARQ) and Forward Error Correction. HARQ has the advantage that error correction works effectively through retransmission even on transmission channels where communication quality varies. In particular, by combining the reception results of the initial transmission and the retransmission when retransmitting, it is possible to achieve further quality improvement.

[0023] An example of a retransmission method will be explained below. If the receiving side is unable to decode the received data correctly, in other words, if a CRC (Cyclic Redundancy Check) error occurs (CRC=NG), the receiving side will send a "Nack" to the sending side. The sending side, having received the "Nack," will retransmit the data. If the receiving side is able to decode the received data correctly, in other words, if no CRC error occurs (CRC=OK), the receiving side will send an "Ack" to the sending side. The sending side, having received the "Ack," will send the next data.

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

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

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

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

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

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

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

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

[0032] The location of a communication terminal is tracked in units of an area consisting of one or more cells. Location tracking is performed to track the location of the communication terminal even when it is in standby mode and to enable the communication terminal to be called, in other words, to allow the communication terminal to receive calls. The area used for tracking the location of this communication terminal is called a tracking area.

[0033] 3GPP is also working on the development of the Long Term Evolution Advanced (LTE-A) standard as Release 10 (see Non-Patent Documents 3 and 4). LTE-A is based on the LTE wireless communication system, and is configured by adding several new technologies to it.

[0034] In the LTE-A system, carrier aggregation (CA) is being considered, which aggregates two or more component carriers (CCs) (also called "aggregation") to support wider frequency bandwidths (transmission bandwidths) up to 100 MHz. CA is described in Non-Patent Document 1.

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

[0036] Depending on the UE's capabilities, a secondary cell (SCell) is configured to form a serving cell set together with the PCell. In the downlink, the carrier corresponding to the SCell is the downlink secondary component carrier (DL SCC). In the uplink, the carrier corresponding to the SCell is the uplink secondary component carrier (UL SCC).

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

[0038] New technologies for LTE-A include wider bandwidth extension, coordinated multiple point transmission and reception (CoMP), etc. CoMP, which is being considered for LTE-A by 3GPP, is described in Non-Patent Document 1.

[0039] Furthermore, in order to handle future massive traffic volumes, 3GPP is considering using small eNBs (hereinafter sometimes referred to as "small-scale base station devices") that configure small cells. For example, technologies are being considered that aim to increase communication capacity by installing a large number of small eNBs and configuring a large number of small cells to improve frequency utilization efficiency. Specifically, there is dual connectivity (abbreviated as DC), in which a UE connects to two eNBs to communicate. DC is described in Non-Patent Document 1.

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

[0041] Mobile network traffic volume is on the rise, and communication speeds are also increasing. Once LTE and LTE-A are fully operational, communication speeds are expected to increase even further.

[0042] Furthermore, in response to the increasing sophistication of mobile communications, fifth-generation (hereinafter sometimes referred to as "5G") wireless access systems are being considered, with the goal of launching services after 2020. For example, in Europe, an organization called METIS has compiled requirements for 5G (see Non-Patent Document 5).

[0043] The requirements for a 5G wireless access system are that it will have 1,000 times the system capacity, 100 times the data transmission speed, one-tenth (1 / 10) the data processing delay, and 100 times the number of simultaneous connections of communication terminals compared to an LTE system, while also achieving further reductions in power consumption and lower equipment costs.

[0044] To meet these demands, 3GPP is currently working on 5G standards as Release 15 (see Non-Patent Documents 6 to 18). 5G wireless access technology is called "New Radio Access Technology" ("New Radio" is abbreviated as "NR").

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

[0046] The NR access method uses OFDM in the downlink direction and OFDM and DFT-s-OFDM (DFT-spread-OFDM) in the uplink direction.

[0047] NR allows the use of higher frequencies than LTE in order to improve transmission speeds and reduce processing delays.

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

[0049] The NR frame structure supports various subcarrier spacings, i.e., various numerologies. In NR, regardless of the numerology, one subframe is 1 millisecond and one slot consists of 14 symbols. The number of slots included in one subframe is one in a numerology with a subcarrier spacing of 15 kHz, but increases in proportion to the subcarrier spacing in other numerologies (see Non-Patent Document 13 (TS38.211 V16.0.0)).

[0050] In NR, downlink synchronization signals are transmitted from base stations as synchronization signal bursts (hereinafter sometimes referred to as SS bursts) at predetermined intervals for a predetermined duration. SS bursts consist of synchronization signal blocks (hereinafter sometimes referred to as SS blocks) for each beam of the base station. The base station transmits the SS blocks of each beam within the duration of the SS burst, changing the beam. SS blocks consist of P-SS, S-SS, and PBCH.

[0051] In NR, the influence of phase noise is reduced by adding a Phase Tracking Reference Signal (PTRS) as a downlink reference signal for NR. PTRS is also added to the uplink reference signal, just like in the downlink.

[0052] In NR, slot format indication (SFI) has been added to the information contained in the PDCCH in order to flexibly switch between DL and UL within a slot.

[0053] In addition, in NR, the base station pre-configures a portion of the carrier frequency band (hereinafter sometimes referred to as the Bandwidth Part (BWP)) for the UE, and the UE transmits and receives data to and from the base station using this BWP, thereby reducing power consumption in the UE.

[0054] 3GPP is considering the following DC forms: DC by LTE base stations and NR base stations connected to EPC, DC by NR base stations connected to a 5G core system, and DC by LTE base stations and NR base stations connected to a 5G core system (see Non-Patent Documents 12, 16, and 19).

[0055] 3GPP is also studying several new technologies. For example, non-public networks (NPNs) are being studied (see Non-Patent Documents 23, 24, and 31). 3GPP is also studying support for services (or applications) using side link (SL) communication in both EPS and the 5G core system (see Non-Patent Documents 1, 16, 22, 26, 27, and 28). Services using SL communication include, for example, V2X services and proximity services. [Prior art documents] [Non-patent literature]

[0056] [Non-Patent Document 1] 3GPP TS 36.300 V16.0.0 [Non-patent document 2] 3GPP S1-083461 [Non-patent document 3] 3GPP TR 36.814 V9.2.0 [Non-patent document 4] 3GPP TR 36.912 V15.0.0 [Non-licensed document 5] "Scenarios, requirements and KPIs for 5G mobile and wireless system", ICT-317669-METIS / D1.1

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Summary of the Invention

Problems to be Solved by the Invention

[0057] One form of NPN is the Public Network Integrated NPN (NPN) that is integrated into a public network. In a PNI-NPN, a CAG (Closed Access Group) is used to identify the network (see Non-Patent Document 27 (TS23.501)). Information related to the CAG is called CAG information, and the CAG information is notified to the UE from the AMF when the UE registers with the network (Non-Patent Document 25 (TS23.502)). As a method for switching CAG information, network-initiated switching and UE-initiated switching have been proposed (see Non-Patent Documents 24 (RP-20XXXX) and 31 (R2-2001155)).

[0058] However, the procedure for UE-initiated CAG information switching is not disclosed. As a result, the UE cannot initiate CAG information switching, and there is a risk that communications after the CAG information switching will not meet the specified QoS.

[0059] Furthermore, support for various services using SL communication (also referred to as PC5 communication) is being considered in both EPS and the 5G core system (Non-Patent Documents 1, 16, 20, 21, 22, and 23). In SL communication, communication is performed between terminals. In SL communication, not only direct communication between terminals but also indirect communication between UEs via a relay and communication between a UE and a network via a relay have been proposed (Non-Patent Document 29). In such communication via a relay, the issues are how to satisfy the QoS required for the service, how to satisfy the low latency characteristics required for the service, and how to improve the utilization efficiency of resources used for SL communication.

[0060] In view of the above-mentioned problems, one of the objects of the present disclosure is to provide good communication by ensuring the QoS required for the service. [Means for solving the problem]

[0061] A first communication terminal device according to the present disclosure is a first communication terminal device in a communication system, the communication system comprising a plurality of communication terminal devices performing sidelink communication via a PC5 interface and a network including one or more core network nodes, the plurality of communication terminal devices including the first communication terminal device and a second communication terminal device, the one or more core network nodes including a Session Management Function (SMF), the first communication terminal device being a relay communication terminal device that performs relaying between the second communication terminal device and the network, the first communication terminal device establishing a PDU (Protocol Data Unit) session between the first communication terminal device and the network, a PDU session used for the relay, and the first communication terminal device being configured to transmit information regarding the second communication terminal device to the SMF in a procedure for establishing the PDU session for the relay. A second communication terminal device according to the present disclosure is a second communication terminal device in a communication system, the communication system comprising a plurality of communication terminal devices performing sidelink communication via a PC5 interface and a network including one or more core network nodes, the plurality of communication terminal devices including a first communication terminal device and the second communication terminal device, the first communication terminal device being a relay communication terminal device that performs relaying between the second communication terminal device and the network, a PDU (Protocol Data Unit) session between the first communication terminal device and the network, a PDU session used for the relaying, is established, and the second communication terminal device is configured to perform discovery processing between the first communication terminal device and the second communication terminal device after the PDU session for the relaying is established. The communication system of the present disclosure is a communication system comprising a plurality of communication terminal devices that perform sidelink communication via a PC5 interface, the plurality of communication terminal devices including a first communication terminal device and a second communication terminal device, and a network including one or more core network nodes including a Session Management Function (SMF), wherein the first communication terminal device is a relay communication terminal device that performs relaying between the second communication terminal device and the network, the first communication terminal device establishes a PDU (Protocol Data Unit) session between the first communication terminal device and the network, the PDU session being used for the relay, and the first communication terminal device is configured to transmit information regarding the second communication terminal device to the SMF in a procedure for establishing the PDU session for the relay. [Effects of the Invention]

[0062] According to the present disclosure, good communication can be provided.

[0063] The objects, features, aspects, and advantages of the present disclosure will become more apparent from the following detailed description and the accompanying drawings. [Brief explanation of the drawings]

[0064] [Figure 1] FIG. 1 is an explanatory diagram showing the configuration of a radio frame used in an LTE communication system. [Figure 2] 1 is a block diagram showing the overall configuration of an LTE communication system 200 being discussed in 3GPP. [Figure 3] FIG. 2 is a block diagram showing the overall configuration of a communication system 210 conforming to the NR standard under discussion in 3GPP. [Figure 4] This is a diagram illustrating the configuration of DC using eNB and gNB connected to EPC. [Figure 5] This is a diagram of the DC configuration using gNB connected to the NG core. [Figure 6] This is a diagram illustrating the configuration of DC using eNB and gNB connected to the NG core. [Figure 7] This is a diagram illustrating the configuration of DC using eNB and gNB connected to the NG core. [Figure 8] FIG. 3 is a block diagram showing the configuration of a mobile terminal 202 shown in FIG. [Figure 9] FIG. 3 is a block diagram showing the configuration of a base station 203 shown in FIG. [Figure 10] FIG. 2 is a block diagram illustrating the configuration of an MME. [Figure 11] A block diagram showing the configuration of 5GC. [Figure 12] 1 is a flowchart showing an outline of operations from cell search to standby operation performed by a communication terminal (UE) in an LTE communication system. [Figure 13] FIG. 1 is a diagram illustrating an example of a cell configuration in an NR system. [Figure 14] A sequence diagram showing the operation of switching CAG information led by the UE in embodiment 1. [Figure 15] FIG. 11 is a schematic diagram showing cells in which a high-altitude UE can receive signals, according to the second embodiment. [Figure 16] FIG. 11 is a sequence diagram showing operations of detecting PCI collision by a UE and changing the PCI of a serving cell according to the second embodiment. [Figure 17] FIG. 11 is a sequence diagram showing operations of detecting PCI collision by a UE and changing the PCI of a conflicting cell according to the second embodiment. [Figure 18] FIG. 11 is a sequence diagram showing operations of detecting PCI collision by a UE and changing the PCI of a serving cell according to the second embodiment. [Figure 19] This is a sequence diagram showing the operation of PCI collision detection by the UE and PCI change in response to an instruction from AMF, in accordance with the second embodiment. [Figure 20] FIG. 11 is a sequence diagram showing a first example of a method for performing communication between a UE and a NW via a relay UE according to the third embodiment. [Figure 21]FIG. 11 is a sequence diagram showing a second example of a method for performing communication between a UE and a NW via a relay UE according to the third embodiment. [Figure 22] A sequence diagram showing a method for modifying a PDU session for relay between a relay UE and a CN node for embodiment 3. [Figure 23] A sequence diagram showing an example of a method in which a remote UE obtains an SLRB configuration between the remote UE and the relay UE from a gNB to which the relay UE is connected, for variant example 1 of embodiment 3. [Figure 24] FIG. 11 is a sequence diagram showing an example of a method in which a relay UE sets up an SLRB between a remote UE and the relay UE, according to a first modification of the third embodiment. [Figure 25] FIG. 13 is a sequence diagram showing a first example of a method for transmitting and receiving data at a CP in a PC 5 according to the fourth embodiment. [Figure 26] FIG. 13 is a sequence diagram showing a second example of a method for transmitting and receiving data at a CP in a PC 5 according to the fourth embodiment. [Figure 27] FIG. 13 is a sequence diagram showing a third example of a method for transmitting and receiving data using a CP in a PC 5 according to the fourth embodiment. [Figure 28] FIG. 13 is a diagram illustrating a first example of a data flow in UE-TX when transmitting data via CP in accordance with the fourth embodiment. [Figure 29] FIG. 13 is a diagram illustrating a second example of a data flow in UE-TX when transmitting data via CP, in accordance with the fourth embodiment. [Figure 30] FIG. 13 is a diagram illustrating a third example of a data flow in UE-TX when transmitting data via CP, in accordance with the fourth embodiment. [Figure 31] FIG. 13 is a sequence diagram showing a first example of a method for transmitting data at a CP via a relay UE, in accordance with a first modification of the fourth embodiment. [Figure 32] FIG. 13 is a sequence diagram showing a second example of a method for transmitting data at a CP via a relay UE, in accordance with the first modification of the fourth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0065] Embodiment 1 Fig. 2 is a block diagram showing the overall configuration of an LTE communication system 200 being discussed in 3GPP. Fig. 2 will now be described. The radio access network is called E-UTRAN (Evolved Universal Terrestrial Radio Access Network) 201. A mobile terminal device (hereinafter referred to as "mobile terminal (User Equipment: UE)") 202, which is a communication terminal device, is capable of wireless communication with a base station device (hereinafter referred to as "base station (E-UTRAN NodeB: eNB)") 203, and transmits and receives signals via wireless communication.

[0066] Here, the term "communication terminal device" includes not only mobile terminal devices such as mobile cell phone terminal devices, but also stationary devices such as sensors. In the following description, the term "communication terminal device" may be simply referred to as a "communication terminal."

[0067] If control protocols for mobile terminals 202, such as RRC (Radio Resource Control), and user planes (hereinafter sometimes referred to as U-Planes), such as PDCP (Packet Data Convergence Protocol), RLC (Radio Link Control), MAC (Medium Access Control), and PHY (Physical layer), terminate at base stations 203, E-UTRAN is composed of one or more base stations 203.

[0068] The control protocol RRC (Radio Resource Control) between the mobile terminal 202 and the base station 203 performs broadcasting, paging, RRC connection management, etc. The states of the base station 203 and the mobile terminal 202 in RRC include RRC_IDLE and RRC_CONNECTED.

[0069] In RRC_IDLE, PLMN (Public Land Mobile Network) selection, system information (SI) broadcast, paging, cell reselection, mobility, etc. are performed. In RRC_CONNECTED, the mobile terminal has an RRC connection and can transmit and receive data with the network. In addition, in RRC_CONNECTED, handover (HO), measurement of neighbor cells, etc. are performed.

[0070] The base station 203 is configured by one or more eNBs 207. A system configured by the core network EPC (Evolved Packet Core) and the radio access network E-UTRAN 201 is called an EPS (Evolved Packet System). The core network EPC and the radio access network E-UTRAN 201 are sometimes collectively referred to as a "network."

[0071] The eNB 207 is connected to a Mobility Management Entity (MME), or a Serving Gateway (S-GW), or an MME / S-GW unit (hereinafter sometimes referred to as an "MME unit") 204 including an MME and an S-GW via an S1 interface, and control information is communicated between the eNB 207 and the MME unit 204. Multiple MME units 204 may be connected to one eNB 207. The eNBs 207 are connected to each other via an X2 interface, and control information is communicated between the eNBs 207.

[0072] The MME unit 204 is an upper device, specifically an upper node, and controls the connection between the eNB 207, which is a base station, and the mobile terminal (UE) 202. The MME unit 204 constitutes the EPC, which is a core network. The base station 203 constitutes the E-UTRAN 201.

[0073] Base station 203 may configure one cell or multiple cells. Each cell has a predetermined range as coverage, which is the range within which communication with mobile terminal 202 is possible, and performs wireless communication with mobile terminal 202 within the coverage. When one base station 203 configures multiple cells, each cell is configured to be able to communicate with mobile terminal 202.

[0074] Figure 3 is a block diagram showing the overall configuration of a 5G communication system 210 being discussed in 3GPP. The following describes Figure 3. The radio access network is referred to as a Next Generation Radio Access Network (NG-RAN) 211. The UE 202 is capable of wireless communication with an NR base station device (hereinafter referred to as an "NR base station (NG-RAN NodeB: gNB)") 213, and transmits and receives signals via wireless communication. The core network is referred to as a 5G Core (5GC).

[0075] If control protocols for UE202, such as RRC (Radio Resource Control), and user planes (hereinafter sometimes referred to as U-Planes), 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 an NR base station 213, the NG-RAN is composed of one or more NR base stations 213.

[0076] The function of the control protocol RRC (Radio Resource Control) between the UE 202 and the NR base station 213 is the same as that of LTE. The states of the NR base station 213 and the UE 202 in the RRC include RRC_IDLE, RRC_CONNECTED, and RRC_INACTIVE.

[0077] RRC_IDLE and RRC_CONNECTED are the same as those in the LTE system. RRC_INACTIVE maintains the connection between the 5G core and the NR base station 213, and performs system information (SI), paging, cell reselection, mobility, and the like.

[0078] The gNB 217 is connected to an AMF / SMF / UPF unit (hereinafter sometimes referred to as the "5GC unit") 214, which includes an Access and Mobility Management Function (AMF), a Session Management Function (SMF), or a User Plane Function (UPF), or an AMF, SMF, and UPF, via an NG interface. Control information and / or user data are communicated between the gNB 217 and the 5GC unit 214. The NG interface is a collective term for the N2 interface between the gNB 217 and the AMF, the N3 interface between the gNB 217 and the UPF, the N11 interface between the AMF and the SMF, and the N4 interface between the UPF and the SMF. Multiple 5GC units 214 may be connected to one gNB 217. The gNBs 217 are connected to each other via an Xn interface, and control information and / or user data are communicated between the gNBs 217.

[0079] The NR base station 213 may configure one or more cells, similar to the base station 203. When one NR base station 213 configures multiple cells, each cell is configured to be able to communicate with the UE 202.

[0080] The gNB 217 may be divided into a central unit (hereinafter, sometimes referred to as a CU) 218 ​​and distributed units (hereinafter, sometimes referred to as DUs) 219. One CU 218 is configured in the gNB 217. One or more DUs 219 are configured in the gNB 217. The CU 218 is connected to the DU 219 via an F1 interface, and control information and / or user data is communicated between the CU 218 and the DU 219.

[0081] A 5G communication system may include a Unified Data Management (UDM) function and a Policy Control Function (PCF) described in Non-Patent Document 27 (3GPP TS23.501 V16.4.0). The UDM and / or PCF may be included in the 5GC unit in FIG.

[0082] A 5G communication system may include a Non-3GPP Interworking Function (N3IWF) described in Non-Patent Document 27 (3GPP TS23.501 V16.4.0). The N3IWF may terminate an Access Network (AN) between the UE and the N3IWF in non-3GPP access between the UE and the N3IWF.

[0083] Fig. 4 is a diagram showing a DC configuration by eNBs and gNBs connected to EPC. In Fig. 4, solid lines indicate U-Plane connections, and dashed lines indicate C-Plane connections. In Fig. 4, eNB223-1 serves as the master base station, and gNB224-2 serves as the secondary base station (this DC configuration may be referred to as EN-DC). Fig. 4 shows an example in which U-Plane connection between MME unit 204 and gNB224-2 is made via eNB223-1, but it may also be made directly between MME unit 204 and gNB224-2.

[0084] Figure 5 is a diagram showing the configuration of DC by a gNB connected to an NG core. In Figure 5, solid lines indicate U-Plane connections, and dashed lines indicate C-Plane connections. In Figure 5, gNB 224-1 is the master base station, and gNB 224-2 is the secondary base station (this DC configuration may be referred to as NR-DC). Figure 5 shows an example in which U-Plane connection between 5GC unit 214 and gNB 224-2 is made via gNB 224-1, but it may also be made directly between 5GC unit 214 and gNB 224-2.

[0085] Figure 6 is a diagram showing a DC configuration by eNB and gNB connected to the NG core. In Figure 6, solid lines indicate U-Plane connections, and dashed lines indicate C-Plane connections. In Figure 6, eNB226-1 is the master base station, and gNB224-2 is the secondary base station (this DC configuration may be referred to as NG-EN-DC). Figure 6 shows an example in which U-Plane connection between 5GC unit 214 and gNB224-2 is made via eNB226-1, but it may also be made directly between 5GC unit 214 and gNB224-2.

[0086] Figure 7 is a diagram showing another configuration of DC by eNB and gNB connected to the NG core. In Figure 7, solid lines indicate U-Plane connections, and dashed lines indicate C-Plane connections. In Figure 7, gNB224-1 is the master base station, and eNB226-2 is the secondary base station (this DC configuration may be referred to as NE-DC). Figure 7 shows an example in which U-Plane connection between 5GC unit 214 and eNB226-2 is made via gNB224-1, but it may also be made directly between 5GC unit 214 and eNB226-2.

[0087] FIG. 8 is a block diagram showing the configuration of mobile terminal 202 shown in FIG. 2. The transmission process of mobile terminal 202 shown in FIG. 8 will be described. First, control data from protocol processing unit 301 and user data from application unit 302 are stored in transmission data buffer unit 303. The data stored in transmission data buffer unit 303 is passed to encoder unit 304, where it is subjected to encoding processes such as error correction. Some data may be output directly from transmission data buffer unit 303 to modulation unit 305 without being encoded. The data encoded by encoder unit 304 is modulated by modulation unit 305. Precoding in MIMO may be performed by modulation unit 305. The modulated data is converted into a baseband signal, and then output to frequency conversion unit 306, where it is converted into a radio transmission frequency. Thereafter, a transmission signal is transmitted to base station 203 from antennas 307-1 to 307-4. Although FIG. 8 illustrates an example in which the number of antennas is four, the number of antennas is not limited to four.

[0088] Furthermore, the reception process of mobile terminal 202 is performed as follows. Radio signals from base station 203 are received by antennas 307-1 to 307-4. The received signals are converted from a radio reception frequency to a baseband signal by frequency conversion unit 306, and demodulated by demodulation unit 308. Demodulation unit 308 may also perform weight calculation and multiplication processing. The demodulated data is passed to decoder unit 309, where decoding processing such as error correction is performed. Of the decoded data, control data is passed to protocol processing unit 301, and user data is passed to application unit 302. A series of processes of mobile terminal 202 is controlled by control unit 310. Therefore, although control unit 310 is omitted in FIG. 8, it is connected to each unit 301 to 309. In FIG. 8, the number of antennas used by mobile terminal 202 for transmission and the number of antennas used for reception may be the same or different.

[0089] 2. The transmission process of the base station 203 shown in FIG. 9 will be described. The EPC communication unit 401 transmits and receives data between the base station 203 and the EPC (such as the MME unit 204). The 5GC communication unit 412 transmits and receives data between the base station 203 and the 5GC (such as the 5GC unit 214). The other base station communication unit 402 transmits and receives data with other base stations. The EPC communication unit 401, the 5GC communication unit 412, and the other base station communication unit 402 each exchange information with the protocol processing unit 403. The control data from the protocol processing unit 403, and the user data and control data from the EPC communication unit 401, the 5GC communication unit 412, and the other base station communication unit 402 are stored in the transmission data buffer unit 404.

[0090] The data stored in transmission data buffer unit 404 is passed to encoder unit 405, where it undergoes encoding processing such as error correction. Some data may be output directly from transmission data buffer unit 404 to modulation unit 406 without undergoing encoding processing. The encoded data is modulated by modulation unit 406. MIMO precoding may be performed by modulation unit 406. The modulated data is converted into a baseband signal, and then output to frequency conversion unit 407, where it is converted into a radio transmission frequency. Thereafter, a transmission signal is transmitted to one or more mobile terminals 202 from antennas 408-1 to 408-4. Although FIG. 9 illustrates an example in which the number of antennas is four, the number of antennas is not limited to four.

[0091] The reception process of the base station 203 is performed as follows: A radio signal from one or more mobile terminals 202 is received by an antenna 408. The received signal is converted from a radio reception frequency to a baseband signal by a frequency conversion unit 407, and demodulated by a demodulation unit 409. The demodulated data is passed to a decoder unit 410, where decoding processes such as error correction are performed. Of the decoded data, control data is passed to the protocol processing unit 403, the 5GC communication unit 412, the EPC communication unit 401, or the other base station communication unit 402, and user data is passed to the 5GC communication unit 412, the EPC communication unit 401, and the other base station communication unit 402. A series of processes of the base station 203 is controlled by a control unit 411. Therefore, although the control unit 411 is omitted in FIG. 9, it is connected to each unit 401 to 410. In FIG. 9, the number of antennas used for transmission by the base station 203 and the number of antennas used for reception may be the same or different.

[0092] 9 is a block diagram showing the configuration of base station 203, but base station 213 may have a similar configuration. In addition, in FIGS. 8 and 9, the number of antennas of mobile terminal 202 and the number of antennas of base station 203 may be the same or different.

[0093] 10 is a block diagram showing the configuration of an MME. FIG. 10 shows the configuration of an MME 204a included in the MME unit 204 shown in FIG. 2 described above. A PDN GW communication unit 501 transmits and receives data between the MME 204a and a PDN GW. A base station communication unit 502 transmits and receives data via the S1 interface between the MME 204a and a base station 203. If the data received from the PDN GW is user data, the user data is passed from the PDN GW communication unit 501 to the base station communication unit 502 via a user plane communication unit 503, and transmitted to one or more base stations 203. If the data received from the base station 203 is user data, the user data is passed from the base station communication unit 502 to the PDN GW communication unit 501 via the user plane communication unit 503, and transmitted to the PDN GW.

[0094] If the data received from the PDN GW is control data, the control data is passed from the PDN GW communication unit 501 to the control plane control unit 505. If the data received from the base station 203 is control data, the control data is passed from the base station communication unit 502 to the control plane control unit 505.

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

[0096] The MME 204a distributes paging signals to one or more base stations 203. The MME 204a also performs mobility control in an idle state. The MME 204a manages a tracking area list when the mobile terminal is in an idle state and an active state. The MME 204a initiates a paging protocol by transmitting a paging message to a cell belonging to a tracking area in which the UE is registered. The idle state mobility management unit 505-3 may manage the CSG, CSG ID, and whitelist of the eNB 207 connected to the MME 204a.

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

[0098] If the data received from the Data Network is control data, the control data is passed from the Data Network communication unit 521 to the session management unit 527 via the user plane communication unit 523. The session management unit 527 passes the control data to the control plane control unit 525. If the data received from the base station 203 and / or base station 213 is control data, the control data is passed from the base station communication unit 522 to the control plane control unit 525. The control plane control unit 525 passes the control data to the session management unit 527.

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

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

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

[0102] P-SS and S-SS are collectively called the Synchronization Signal (SS). The Synchronization Signal (SS) is assigned a synchronization code that corresponds one-to-one to the PCI assigned to each cell. 504 different PCIs are being considered. These 504 different PCIs are used to achieve synchronization and to detect (identify) the PCI of the synchronized cell.

[0103] Next, in step ST602, for the synchronized cell, a cell-specific reference signal (CRS), which is a reference signal (RS) transmitted from the base station for each cell, is detected and the RS received power (Reference Signal Received Power: RSRP) is measured. The RS uses a code that has a one-to-one correspondence with the PCI. By correlating with this code, it is possible to separate the cell from other cells. By deriving the code for the RS of the cell from the PCI identified in step ST601, it is possible to detect the RS and measure the RS received power.

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

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

[0106] Next, in step ST605, the DL-SCH of the cell is received based on the cell configuration information in the MIB, and SIB (System Information Block) 1 is obtained from the broadcast information BCCH. SIB 1 includes information on access to the cell, information on cell selection, and scheduling information for other SIBs (SIBk; k is an integer greater than or equal to 2). SIB 1 also includes a tracking area code (TAC).

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

[0108] If the comparison in step ST606 shows that the TAC received in step ST605 is the same as the TAC included in the tracking area list, the communication terminal enters standby mode in the cell. If the comparison shows that the TAC received in step ST605 is not included in the tracking area list, the communication terminal requests a core network (EPC) including an MME, etc., to change the tracking area in order to perform a Tracking Area Update (TAU) through the cell.

[0109] In the example shown in Fig. 12, an example of operations from cell search to standby in the LTE system is shown, but in the NR system, in addition to the best cell, the best beam may be selected in step ST603. Also, in the NR system, beam information, for example, a beam identifier, may be acquired in step ST604. Also, in the NR system, scheduling information of remaining minimum SI (RMSI) may be acquired in step ST604. In the NR system, RMSI may be received in step ST605.

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

[0111] The widespread use of smartphones and tablet devices has led to an explosive increase in cellular wireless communication traffic, raising concerns about a shortage of wireless resources worldwide. In response to this, efforts are being made to develop small cells and promote spatial separation in order to improve frequency utilization efficiency.

[0112] In a conventional cell configuration, a cell configured by an eNB has a relatively wide coverage area. Conventionally, a cell is configured so that a certain area is covered by the relatively wide coverage areas of multiple cells configured by multiple eNBs.

[0113] In the case of small cell configuration, a cell configured by an eNB has a narrower coverage area than a cell configured by a conventional eNB. Therefore, as in the past, a larger number of small cell configuration eNBs are required to cover a certain area compared to conventional eNBs.

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

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

[0116] The small eNB may be, for example, a low-power node, a local area node, a hotspot, etc. Also, the small eNB may be a pico eNB constituting a pico cell, a femto eNB constituting a femto cell, a HeNB, a remote radio head (RRH), a remote radio unit (RRU), a remote radio equipment (RRE), or a relay node (RN). Also, the small eNB may be a "local area base station" or a "home base station" as described in Non-Patent Document 7.

[0117] FIG. 13 shows an example of a cell configuration in NR. In an NR cell, narrow beams are formed and transmitted while changing direction. In the example shown in FIG. 13, at a certain time, base station 750 transmits and receives signals to and from a mobile terminal using beam 751-1. At another time, base station 750 transmits and receives signals to and from a mobile terminal using beam 751-2. In a similar manner, base station 750 transmits and receives signals to and from a mobile terminal using one or more of beams 751-3 to 751-8. In this way, base station 750 configures a wide-area cell.

[0118] 13 shows an example in which the number of beams used by the base station 750 is 8, but the number of beams may be different from 8. Also, in the example shown in FIG. 13, the number of beams used simultaneously by the base station 750 is 1, but it may be multiple.

[0119] 3GPP supports Side Link (SL) for D2D (Device to Device) communication and V2V (Vehicle to Vehicle) communication (see Non-Patent Document 1 and Non-Patent Document 16). SL is defined by the PC5 interface.

[0120] The physical channels used for SL (see Non-Patent Document 1) will be described below. A physical sidelink broadcast channel (PSBCH) carries information related to the system and synchronization, and is transmitted from a UE.

[0121] The physical sidelink discovery channel (PSDCH) carries sidelink discovery messages from the UE.

[0122] The physical sidelink control channel (PSCCH) carries control information from the UE for sidelink and V2X sidelink communications.

[0123] The physical sidelink shared channel (PSSCH) carries data from the UE for sidelink and V2X sidelink communications.

[0124] The physical sidelink feedback channel (PSFCH) carries HARQ feedback on the sidelink from UEs that receive a PSSCH transmission to the UE that transmitted the PSSCH.

[0125] The transport channel used for SL (see Non-Patent Document 1) will be described below. The sidelink broadcast channel (SL-BCH) has a predetermined transport format and is mapped to the PSBCH, which is a physical channel.

[0126] The Sidelink Discovery Channel (SL-DCH) has periodic broadcast transmissions of a fixed size and a predetermined format. The SL-DCH supports both UE autonomous resource selection and eNB-scheduled resource allocation. UE autonomous resource selection involves a collision risk, whereas when the UE is allocated dedicated resources by the eNB, there is no collision. The SL-DCH supports HARQ combining but not HARQ feedback. The SL-DCH is mapped to the PSDCH, a physical channel.

[0127] The Sidelink Shared Channel (SL-SCH) supports broadcast transmission. It supports both UE autonomous resource selection and eNB-scheduled resource allocation. While UE autonomous resource selection involves a collision risk, there is no collision when the UE is allocated dedicated resources by the eNB. The SL-SCH also supports HARQ combining but not HARQ feedback. The SL-SCH also supports dynamic link adaptation by varying transmit power, modulation, and coding. The SL-SCH is mapped to the PSSCH, a physical channel.

[0128] The logical channels used for SL (see Non-Patent Document 1) will be described. The Sidelink Broadcast Control Channel (SBCCH) is a sidelink channel for broadcasting sidelink system information from one UE to other UEs. The SBCCH is mapped to the SL-BCH, which is a transport channel.

[0129] The Sidelink Traffic Channel (STCH) is a point-to-multipoint traffic channel for transmitting user information from one UE to other UEs. The STCH is used only by UEs with sidelink communication capability and UEs with V2X sidelink communication capability. Point-to-point communication between two sidelink-capable UEs is also realized by the STCH. The STCH is mapped to the SL-SCH, a transport channel.

[0130] The Sidelink Control Channel (SCCH) is a control channel for transmitting control information from one UE to another UE. The SCCH is mapped to the SL-SCH, which is a transport channel.

[0131] 3GPP is considering supporting V2X communication in NR as well. The study of V2X communication in NR is being carried out based on the LTE system and LTE-A system, but the following changes and additions have been made from the LTE system and LTE-A system.

[0132] In LTE, SL communication was limited to broadcast. In NR, support for unicast and groupcast as SL communication in addition to broadcast is being considered (see Non-Patent Document 26 (TS23.287)).

[0133] For unicast and groupcast communications, support for HARQ feedback (Ack / Nack), CSI reporting, etc. is being considered.

[0134] Support for PC5-S signaling is being considered to support unicast and groupcast in addition to broadcast in SL communication (see Non-Patent Document 26 (TS23.287)). For example, PC5-S signaling is implemented to establish a link for implementing SL, i.e., PC5 communication. This link is implemented in the V2X layer and is also called a Layer 2 link.

[0135] Furthermore, support for RRC signaling in SL communication is being considered (see Non-Patent Document 26 (TS23.287)). RRC signaling in SL communication is also referred to as PC5 RRC signaling. For example, it has been proposed to notify UE capabilities between UEs performing PC5 communication, and to notify AS layer settings for V2X communication using PC5 communication.

[0136] The CAG information may be switched in the UE. The switching may be initiated by the network or the UE.

[0137] However, the procedure for switching CAG information at the initiative of the UE is not disclosed, which results in a problem in that the UE cannot switch CAG information at its own initiative.

[0138] A solution to the aforementioned problem is disclosed.

[0139] The UE requests the AMF to switch the CAG information. For example, NAS signaling may be used for the request. A new NAS signaling (for example, CAG INFORMATION CHANGE REQUEST) may be provided to request the switching of the CAG information. The switching of the CAG information may be, for example, the addition of a CAG to the allowed CAG list disclosed in Non-Patent Document 27 (TS23.501), the deletion of a CAG from the allowed CAG list, the modification of the allowed CAG list (i.e., the deletion and addition), or the change of "CAG-only information" (see Non-Patent Document 27 (TS23.501)) indicating whether the UE can connect to the network only via a CAG cell.

[0140] The signaling may include information about the CAG information after the switch. The information may be, for example, information about the difference between the CAG information before and after the switch. This may, for example, reduce the size of the signaling.

[0141] The AMF uses the information from the UE to determine whether to change the CAG information of the UE. If it is determined that the CAG information of the UE can be changed, the AMF may instruct the UE to switch the CAG information. The instruction may include the CAG information after switching.

[0142] The AMF may determine the CAG information after switching. For example, the AMF may make the CAG information after switching determined by the AMF different from the CAG information included in the request from the UE. This enables efficient operation of the network, for example, by excluding CAG cells with a large number of serving UEs from the allowed CAG cell list.

[0143] When the determined CAG information differs from the CAG information requested by the UE, the AMF may notify the instruction by including information about the difference. The information may include, for example, information about part or all of the CAG information requested by the UE (for example, information about the CAG information requested by the UE that was not reflected in the CAG information determined by the AMF), or may include information about part or all of the CAG information determined by its own AMF. This allows, for example, the UE to quickly understand which requests from its own UE were not approved.

[0144] If the determined CAG information differs from the CAG information requested by the UE, the AMF may include information about the reason for the difference in the instruction. For example, the information may be that the CAG cell to which the UE requests addition cannot add any more UEs, or that the CAG cell to which the UE requests addition is performing access barring to the UE. This allows, for example, the UE to quickly request a new CAG information change.

[0145] The AMF may not include the CAG information after switching in the instruction. For example, when the CAG information determined by the AMF itself is the same as the CAG information included in the request from the UE, the AMF may not include the CAG information after switching in the instruction. This makes it possible to reduce, for example, the size of NAS signaling.

[0146] The AMF may issue the instruction using the UE configuration update command disclosed in Non-Patent Document 25 (TS23.502) or other NAS signaling. The UE may use the instruction to switch the CAG information of its own UE. The UE may notify the AMF of the completion of the switching of the CAG information. The notification from the UE to the AMF may be issued, for example, using the UE configuration update complete disclosed in Non-Patent Document 25 (TS23.502) or other NAS signaling. The AMF may notify the base station of information related to the change in the UE's CAG information. The base station may notify the UE of the information. The UE may use the information to switch the CAG information.

[0147] The AMF may reject a CAG information switching request from the UE. For example, if the CAG cell to which the UE requests addition cannot add any more UEs, the AMF may reject the request. As another example, if the CAG cell to which the UE requests addition restricts access to the UE (access barring), the AMF may reject the request from the UE. The AMF may notify the UE of the rejection of the request. The notification may include information about the reason for the rejection. The information may be, for example, that the CAG cell to which the UE requests addition cannot add any more UEs, or that the CAG cell to which the UE requests addition restricts access to the UE (access barring). This allows, for example, the UE to quickly execute a new CAG information switching request.

[0148] New NAS signaling may be provided. For example, NAS signaling called "CAG information change request reject" may be provided, or NAS signaling called "UE configuration update request reject" may be provided. The above-mentioned new NAS signaling may be used to notify the UE of the rejection from the AMF. This allows, for example, the UE to quickly understand that the CAG switching request has been rejected.

[0149] A handover of the UE may be performed. For example, if the cell to which the UE is connected does not match the CAG information, a handover of the UE may be performed. The AMF may instruct the gNB to handover the UE to a cell that matches the post-switching CAG information. The gNB may use this information to perform a handover of the UE. As another example, the gNB may use the post-switching CAG information notified by the AMF to perform a handover of the UE. This allows, for example, the UE to quickly start a connection using a cell that matches the post-switching CAG information.

[0150] The AMF may request the CN node to register the UE with a cell that matches the new CAG information, which allows the UE to quickly start communication using the S-NSSAI supported by the cell that matches the new CAG information.

[0151] As another example, the UE may perform cell reselection. For example, if the cell to which the UE is connected does not match the CAG information, the UE may perform cell reselection. This allows, for example, the UE to quickly start connection using a cell that matches the CAG information after switching.

[0152] The UE may perform registration using a cell that matches the post-switching CAG information. In the registration, the method disclosed in the operation of the UE re-registering to the network, which will be described later, may be used. This allows the UE to quickly start communication using the S-NSSAI supported by the cell that matches the post-switching CAG information, for example.

[0153] 14 is a sequence diagram showing the operation of switching CAG information in response to a request from the UE (in other words, at the initiative of the UE). FIG. 14 shows an example in which the gNB does not perform handover of the UE.

[0154] In step ST1401 shown in FIG. 14, the UE requests the AMF to switch CAG information. The request in step ST1401 may be made using, for example, NAS signaling. The request in step ST1401 may include information about the CAG information to be switched. In step ST1403, the AMF uses the request received in step ST1401 to determine whether or not to switch the CAG information of the UE. In the example shown in FIG. 14, the AMF determines that switching the CAG information of the UE is possible.

[0155] In Step ST1405 shown in FIG. 14, the AMF instructs the UE to switch the CAG information. Step ST1405 may be performed using a UE configuration update command disclosed in Non-Patent Document 25 (TS23.502), or may be performed using other NAS signaling. The instruction in Step ST1405 may include a value related to the CAG information after switching. The information included in the instruction in Step ST1405 may be the same as or different from the information included in the request in Step ST1401.

[0156] In Step ST1407, the UE switches the CAG information. In Step ST1409, the UE notifies the AMF of the completion of the CAG information switching. This notification may be made, for example, using the signaling of UE configuration update complete disclosed in Non-Patent Document 25 (TS23.502), or may be made using other NAS signaling. In Step ST1411, the AMF notifies the gNB of the switching of the UE's CAG information. This notification may include information on the CAG information after the switching. In Step ST1413, the gNB determines whether or not a handover of the UE is necessary. For this determination, the information included in the notification in Step ST1411 may be used.

[0157] 14 shows a case where the gNB determines whether or not to allow a UE to hand over, but the UE may determine whether or not to allow a cell reselection. This makes it possible to reduce the amount of processing by the gNB, for example.

[0158] Another solution will be disclosed. The UE may request a UE configuration update from the AMF. The request may include a request to switch the CAG information. For example, NAS signaling may be used for the UE configuration update request from the UE to the AMF. New NAS signaling (for example, CONFIGURATION UPDATE REQUEST) may be provided for use in requesting a UE configuration update. This allows, for example, the UE to update the UE configuration together with updating the CAG information, thereby reducing the amount of signaling between the UE and the AMF.

[0159] Another solution will be disclosed. The UE may request a registration change to the AMF. The request may include a request to switch CAG information. The request may include a UE configuration update request. For example, NAS signaling may be used for the registration change request from the UE to the AMF. New NAS signaling (e.g., REGISTRATION MODIFICATION REQUEST) may be provided for use in requesting a registration change. This allows, for example, the UE to update the CAG information and change the UE's registration, thereby reducing the amount of signaling between the UE and the AMF.

[0160] Another solution is disclosed: the UE re-registers with the NW.

[0161] The UE may perform autonomous deregistration with the AMF. This may, for example, reduce the amount of signaling between the UE and the AMF. As another example, the UE may request the AMF to release its registration with the NW. For example, NAS signaling may be used for this request. For example, the NAS signaling used for this request may be the DEREGISTRATION REQUEST disclosed in Non-Patent Document 25 (TS23.502 V16.4.0). This may, for example, enable quick deregistration.

[0162] The UE may send a registration request to the AMF, and the registration request may include information about the CAG information after switching.

[0163] The registration request may include information indicating that the registration is associated with a change in CAG information. The AMF may use the information to register the UE to the NW. This allows, for example, the AMF to quickly register the UE.

[0164] When the CAG information is switched, the UE may transition to the RRC_IDLE state. The state transition may be performed autonomously by the UE in response to the CAG information switch. The base station may instruct the UE to make the state transition. The UE may connect to the base station using the switched CAG information. This may, for example, avoid complex processing in the communication system.

[0165] When the CAG information is switched, the UE may transition to the CM-IDLE state. The UE may use the switched CAG information to re-establish a NAS connection with the AMF. This can, for example, avoid complex processing in the communication system.

[0166] When switching the CAG information, the UE may perform cell reselection using the CAG information after the CAG switching. For example, when the CAG information of the UE is switched from a state where it is not CAG-only connected to a CAG-only connected state, the UE may perform cell reselection only for CAG cells. As another example, when the allowed CAG list of the UE is changed, the UE may perform cell reselection only for cells included in the changed allowed CAG list. This makes it possible, for example, to quickly perform a process of connecting the UE to a network after switching the CAG information.

[0167] As another example of cell reselection, the UE may perform cell reselection using CAG information before the CAG switch. For example, when the UE's CAG information switches from a state where it is not CAG-only connected to a CAG-only connected state, the UE may perform cell reselection to a CAG cell and / or a PLMN cell. As another example, when the UE's allowed CAG list is changed, the UE may perform cell reselection to a cell included in the allowed CAG list before the change, or may perform cell reselection to a cell included in either the old or new CAG list. This allows, for example, the UE to quickly connect to a cell after the CAG information switch.

[0168] When switching CAG information, verification of access control may be performed. For example, verification of access control may be performed whenever switching of CAG information is performed. Alternatively, verification of access control may be performed when, for example, there is a change in access control for the UE as a result of switching of CAG information. This enables, for example, appropriate access control based on the CAG information after switching in the NW.

[0169] As another example of CAG information switching, access control verification may not be performed. For example, access control verification may not be performed necessarily when CAG information switching is performed. Alternatively, access control verification may not be performed, for example, when there is no change in access control for the UE as a result of CAG information switching. This makes it possible to quickly execute processing related to CAG switching, for example.

[0170] When the CAG information is switched, the UE may transition to the RM-DEREGISTERED state. The UE may re-register with the NW using the switched CAG information. This can avoid, for example, the complexity of processing in the communication system.

[0171] As another example of CAG information switching, the UE may maintain the RM-REGISTERED state. Each device of the UE and the network may switch the UE's CAG information while maintaining the UE's registration state. This allows, for example, the CAG switching process to be performed quickly.

[0172] As another example of the CAG information switching, the UE may transition to the RRC_INACTIVE state. The UE may perform cell reselection using the switched CAG information. This may, for example, reduce the complexity of processing in the communication system.

[0173] When switching the CAG information, the UE may maintain the CM-CONNECTED state, which allows the UE to quickly resume communication after switching the CAG information, for example.

[0174] As another example of CAG information switching, the UE may transition to an RRC_CONNECTED state. The UE may continue communication with the original cell using the switched CAG information, or may hand over to another cell. The base station may use the switched CAG information to determine the UE's handover destination cell. This allows, for example, communication between the UE and the NW to be continued before and after the CAG information switching.

[0175] The method disclosed in the first embodiment may be applied to CAG switching. The CAG switching may be a change of the destination CAG. For example, the UE may request the gNB to switch the destination CAG. The request may include information about the destination CAG after the switch. As another example, in the CAG switching, the UE may transition to the RRC_IDLE state, the RRC_INACTIVE state, or the RRC_CONNECTED state. The UE may perform cell reselection, or the base station may decide to handover the UE.

[0176] The method disclosed in the first embodiment may be applied to a standalone NPN (SNPN). For example, the UE may initiate a change of the SNPN access mode. The UE may make an SNPN access mode change request to the AMF. The request may be made, for example, using NAS signaling.

[0177] The method disclosed in the first embodiment may be applied to SNPN switching. For example, the UE may transition to an RRC_IDLE state, an RRC_INACTIVE state, or may maintain an RRC_CONNECTED state. The UE may perform cell reselection, or the base station may decide to handover the UE.

[0178] According to the first embodiment, it becomes possible to quickly switch the CAG information in the UE.

[0179] Embodiment 2 A UE at a high altitude is covered by multiple cells. NR uses higher frequencies than LTE, so the cell radius is smaller in NR than in LTE. Therefore, the number of cells that a UE at a high altitude can receive is greater than in LTE.

[0180] 15 is a schematic diagram showing cells that a high-altitude UE can receive. In FIG. 15, a high-altitude UE 2501 can receive not only cells 2521, 2522, and 2523 of a base station 2520, but also cells 2511, 2512, and 2513 of a base station 2510 adjacent to the base station 2520, and cells 2531, 2532, and 2533 of a base station 2530 that is distant from the base station 2520.

[0181] In the above, the following problem occurs: The number of cells that a UE at a high altitude can receive may exceed the number of PCIs that can be assigned, and the UE may detect multiple cells with the same PCI (hereinafter, this may be referred to as PCI collision). As a result, the UE may mistakenly recognize broadcast information from one cell as broadcast information from another cell, which may cause malfunction in the communication system.

[0182] A method for solving the above-mentioned problems is disclosed.

[0183] Change the PCI of the cell. Arbitration of the PCI of the cell may occur.

[0184] The UE may detect a PCI collision, which may be a PCI collision of the UE's serving cell (i.e., a PCI collision between the serving cell and another cell) or a PCI collision between cells other than the serving cell.

[0185] The UE may detect a PCI collision using the PCI, may detect a PCI collision using a global cell ID (see Non-Patent Document 30 (TS38.331)) included in the SIB1, or may detect a PCI collision using the timing of the SS block and / or the system information. For example, the UE may determine that a PCI collision has occurred if it detects different global cell IDs in the system information from cells with the same PCI. As another example, the UE may determine that a PCI collision has occurred if the timing at which the system information is received differs from the timing of the system information included in the SS block and / or the system information. This may, for example, reduce the amount of processing required for PCI detection.

[0186] The UE may notify the serving cell of information about the PCI collision. For example, RRC signaling may be used for the notification. The RRC signaling may be RRC signaling of a measurement report. A new RRC signaling may be provided for use in notifying the PCI collision. The serving cell may use the information to change the PCI of its own serving cell or change the SS block transmission timing of its own serving cell.

[0187] The information included in the notification from the UE to the serving cell is disclosed below as items (1) to (7).

[0188] (1) Information about the conflicting PCI.

[0189] (2) Information about available PCI numbers.

[0190] (3) Information about the collision cell.

[0191] (4) Information about cells that the UE can receive.

[0192] (5) Information about cells with received power greater than a predetermined threshold.

[0193] (6) Information about the altitude of the own UE.

[0194] (7) A combination of (1) to (6) above.

[0195] The information (1) above may be, for example, the value of the conflicting PCI or a list of multiple values. The conflicting PCI value may be one or multiple. This allows, for example, the serving base station to recognize that the PCIs of its own base station's cells have conflicted.

[0196] The information (2) above may be, for example, the PCI value of an empty cell or a list of multiple values. The cell of the serving base station may use the information (2) above to change the PCI of its own cell. This allows, for example, the cell of the serving base station to avoid PCI collisions with other cells.

[0197] The information (3) above may be, for example, information about the global ID of the conflicting cell, which allows, for example, the UE and / or the cell of the serving base station to uniquely identify the conflicting cell.

[0198] The information (4) above may be, for example, information about a cell received by the UE through a cell search. The information about the cell may be the PCI of the cell, information about the reception strength of the cell, information about the global ID of the cell, or may include a combination of the above information. The serving base station may use the information (4) above to, for example, change the PCI of its own cell. This may, for example, prevent PCI collisions in the cell of the serving base station.

[0199] The information in (5) above may be, for example, the same information as in (4) above. The predetermined threshold may be determined by a standard, or may be determined by the network device and notified to the UE. The network device may be a base station or an AMF. The serving base station may use the information in (5) above to change the PCI of its own cell, for example. This may make it possible to avoid PCI collisions in the cell of the serving base station, for example.

[0200] The information in (6) above may be information about the UE's altitude itself, or information indicating whether the altitude is above or below a predetermined altitude. The serving base station may use the information in (6) above to change the PCI of its own cell or the transmission power. This makes it possible to avoid PCI collisions in the serving base station's cell, for example, even if the UE's altitude becomes even higher.

[0201] The serving cell may broadcast or individually notify the UEs under its control of information indicating that the PCI has been changed. The information may include information regarding a change in the timing of the SS block. The UEs under its control may use the information to re-establish downlink synchronization with the serving cell.

[0202] Figure 16 is a sequence diagram showing the operation of PCI collision detection by a UE and PCI change of a serving cell. In Figure 16, gNB#1 is the base station of the serving cell of the UE, and the cell of gNB#2 has the same PCI as the serving cell of gNB#1. Figure 16 shows an example in which gNB#1 changes the PCI.

[0203] In step ST2501 shown in FIG. 16, communication is established between the UE and gNB#1. In step ST2503, gNB#1 transmits an SS block to the UE. gNB#1 transmits the SS block including information that the PCI number of its own cell is n. In step ST2503, the UE acquires information regarding the PCI number of gNB#1's cell. In step ST2505, gNB#2 transmits the SS block including information that the PCI number of its own cell is n. In step ST2505, the UE acquires information regarding the PCI number of gNB#2's cell.

[0204] In Step ST2507 shown in FIG. 16, the UE detects that the PCIs of gNB#1 and gNB#2 are the same, that is, that the PCIs collide. In Step ST2509, the UE notifies gNB#1 of information about the PCI collision. For example, RRC signaling may be used for this notification. The UE may include, in the information transmitted in Step ST2509, information about the number of the colliding PCI, information about the number of the free PCI, information about the conflicting cell, or a combination of the above information. The information about the conflicting cell may be, for example, the global cell ID of the conflicting cell. The notification in Step ST2509 may include information about the PCI of a cell that the UE can receive, or may include information about the PCI of a cell with received power greater than a predetermined threshold. The notification in Step ST2509 may include information about the global cell ID of the above-mentioned cell. The notification in Step ST2509 may include information about the altitude of the UE. Furthermore, the above-mentioned information included in Step ST2509 may be exchanged between base stations. In Step ST2511, gNB#1 changes the PCI. gNB#1 may change the timing of transmitting SS blocks. The PCI change in gNB#1 may use the information in Step ST2509.

[0205] In Step ST2513 shown in Fig. 16, gNB#1 notifies the UE of information related to the changed PCI. The notification may include information related to the changed SS block transmission timing. In the example shown in Fig. 16, gNB#1 notifies the UE that the PCI has been changed from n to m. The UE may acquire information related to the changed PCI in Step ST2513.

[0206] In step ST2515 shown in FIG. 16, gNB#1 transmits an SS block using the changed PCI number m. The UE establishes downlink synchronization with gNB#1 in step ST2515. In step ST2517, a random access process is performed between the UE and gNB#1, and uplink synchronization between the UE and gNB#1 is established.

[0207] A base station whose PCI conflicts with that of a serving cell may change its PCI. The UE may notify the serving cell of information regarding the PCI conflict. The information may include information regarding the cell that conflicts with the serving cell (hereinafter, may be referred to as a conflicting cell), or may include the information (1) to (7) disclosed as information included in the notification from the UE to the serving cell. The serving cell may request a PCI change from the conflicting cell. The conflicting cell may use the information to determine whether or not to change the PCI. The conflicting cell may notify the serving cell whether or not to change the PCI. If the conflicting cell determines that the PCI change is possible, it may change the PCI of its own cell or change the SS block transmission timing of its own cell. The conflicting cell may broadcast or individually notify the UEs served by the conflicting cell of information indicating that the PCI has been changed. The information may include information regarding the change in the timing of the SS blocks. The served UEs may use the information to re-establish downlink synchronization with the conflicting cell.

[0208] The request may include information about UEs serving the serving cell. For example, the request may include information about the number of UEs serving the serving cell. The conflicting cell may use the information to determine whether to change the PCI. For example, the conflicting cell may change the PCI of its own cell when there are more UEs serving the serving cell than the own cell. This may reduce the number of UEs that need to be resynchronized when the PCI of a cell is changed.

[0209] FIG. 17 is a sequence diagram showing the operation of detecting a PCI collision by a UE and changing the PCI of a conflicting cell. In FIG. 17, gNB#1 is the base station of the serving cell of UE#1, and the cell of gNB#2 has the same PCI as the serving cell of gNB#1. In FIG. 17, UE#1 is a UE served by the cell of gNB#1, and UE#2 is a UE served by the cell of gNB#2. FIG. 17 shows an example in which UE#1 detects a PCI collision and gNB#2 changes the PCI. In the example shown in FIG. 17, the same processes as in FIG. 16 are assigned the same step numbers, and common explanations will be omitted.

[0210] Step ST2501 in Fig. 17 is the same as that in Fig. 16. In Step ST2701, communication between UE#2 and gNB#2 is established.

[0211] Steps ST2503 and ST2505 in Figure 17 are the same as those in Figure 16. In Step ST2705, gNB#2 transmits an SS block to UE#2. gNB#2 transmits the SS block by including information that the PCI number of its own cell is n.

[0212] Steps ST2507 and ST2509 in FIG. 17 are the same as those in FIG. 16. In step ST2710, gNB#1 requests gNB#2 to change the PCI. gNB#1 may include the same information as in step ST2509 in the PCI change request of step ST2710. For example, gNB#1 may include, in the PCI change request of step ST2710, information on the number of the conflicting PCI, information on the number of the free PCI, information on the conflicting cell, or a combination of the above pieces of information. The information on the conflicting cell may be, for example, the global cell ID of the conflicting cell. In step ST2711, gNB#2 changes the PCI. The PCI change in gNB#2 may be performed in the same way as in step ST2511 in FIG. 16.

[0213] In Step ST2712 in Fig. 17, gNB#2 notifies gNB#1 of a response to the PCI change request. In the example shown in Fig. 17, the response may be an affirmative response. From the response in Step ST2712, gNB#1 may recognize that gNB#2 has changed the PCI, or may not change the PCI of the cell of its own base station.

[0214] In steps ST2713, ST2715, and ST2715 in Figure 17, processing similar to steps ST2513, ST2515, and ST2517 in Figure 16 is performed between gNB#2 and UE#2.

[0215] Both of the above may be combined. For example, the cell changing the PCI may switch between the serving cell and the conflicting cell. Arbitration regarding the PCI change may be performed between the serving cell and the conflicting cell. The serving cell may request a PCI change from the conflicting cell. The request may include the same information as described above. The conflicting cell may use the information to determine whether or not to change the PCI. The conflicting cell may notify the serving cell whether or not to change the PCI. If the conflicting cell determines that the PCI change is possible, it may change the PCI of its own cell or change the SS block transmission timing of its own cell. If the conflicting cell determines that the PCI change is not possible, the serving cell may change the PCI or change the SS block transmission timing.

[0216] The conflicting cell may transmit a response to the request to the serving cell. The response may be an affirmative response or a response indicating a rejection. The response may include information regarding the reason. For example, the conflicting cell may include information regarding the reason for the rejection in the rejection response. The reason for the rejection may be, for example, that there is no free PCI, that a high-priority communication is ongoing, that the number of UEs serving the conflicting cell is greater than the number of UEs serving the serving cell, or other reasons. The serving cell may use the information to change the PCI of its own cell or perform other necessary processing. This allows the serving cell to perform appropriate processing depending on the status of the communication system, for example.

[0217] FIG. 18 is a sequence diagram showing the operation of PCI collision detection by a UE and PCI change of a serving cell. In FIG. 18, gNB#1 is the base station of the serving cell of the UE, and the cell of gNB#2 has the same PCI as the serving cell of gNB#1. In FIG. 18, UE#1 is a UE served by the cell of gNB#1, and UE#2 is a UE served by the cell of gNB#2. FIG. 18 shows an example in which gNB#1 changes its PCI as a result of arbitration between gNB#1 and gNB#2. In FIG. 18, the same steps as in FIG. 16 and FIG. 17 are assigned the same step numbers, and common explanations will be omitted.

[0218] Steps ST2501 to ST2710 in FIG. 18 are the same as those in FIG.

[0219] 18, gNB#2 determines that the PCI change request of Step ST2710 is negative, and notifies gNB#1 of a rejection of the PCI change request. The notification may include information on the reason for the rejection of the PCI change. gNB#1 uses the response of Step ST2812 to decide to change the PCI of its own cell.

[0220] Steps ST2511 to ST2517 in FIG. 18 are the same as those in FIG.

[0221] The PCI change may be performed via the AMF. For example, the UE may notify the serving cell of information about the PCI conflict. The serving cell may notify the AMF of the information. The UE may notify the information using RRC signaling. As another example, the UE may notify the information using NAS signaling. The AMF may use the information to instruct the serving cell to change the PCI, or may instruct the conflicting cell to change the PCI. A cell that has received a PCI change instruction from the AMF may instruct its subordinate cells to change the PCI.

[0222] Figure 19 is a sequence diagram showing the operation of PCI collision detection by a UE and PCI change of a serving cell. In Figure 19, gNB#1 is the base station of the serving cell of the UE, and the cell of gNB#2 has the same PCI as the serving cell of gNB#1. In Figure 19, UE#1 is a UE served by the cell of gNB#1, and UE#2 is a UE served by the cell of gNB#2. Figure 19 shows an example in which the AMF determines the PCI change cell to be gNB#1, and gNB#1 changes the PCI. In Figure 19, the same step numbers are assigned to the same processes as in Figures 16, 17, and 18, and common explanations will be omitted.

[0223] Steps ST2501 to ST2509 shown in FIG. 19 are the same as those in FIG.

[0224] In Step ST2910 shown in FIG. 19, gNB#1 notifies the AMF of information related to PCI collision. The gNB#1 may perform the notification of Step ST2910 by using the information included in Step ST2509. In Step ST2911, the AMF decides the cell whose PCI is to be changed. In the example shown in FIG. 19, the AMF decides to change the PCI of the cell of gNB#1. In Step ST2912, the AMF instructs gNB#1 to change the PCI. The PCI change instruction of Step ST2912 may include information related to the cell whose PCI is to be changed (e.g., PCI, global cell ID), may include information related to the PCI before the change, may include information related to the PCI after the change, or may include a plurality of the above-mentioned pieces of information.

[0225] Steps ST2511 to ST2517 in FIG. 19 are the same as those in FIG.

[0226] 19 shows an example in which the UE notifies the gNB#1 of information about PCI collisions, and the gNB#1 notifies the AMF of the information, but the UE may also notify the AMF of the information directly. For example, the UE may notify the information using NAS signaling. This makes it possible to reduce the amount of processing in the gNB#1 related to the processing of the information, for example.

[0227] Another solution is disclosed: Stop transmitting cells.

[0228] The serving cell may stop transmission. The UE may notify the serving cell of information regarding PCI collision. The serving cell may use the information to decide to stop transmission of its own cell. The serving cell may instruct a UE served by the serving cell to perform handover to another cell. The handover may be to another base station or to another cell within the serving cell. The UE served by the serving cell may use the instruction to perform handover to another cell. The serving cell may stop transmission of its own cell after handover of the served UE is completed. For example, the serving cell may stop transmission of its own cell after receiving RRC reconfiguration signaling from the served UE notifying handover completion.

[0229] As another example of stopping transmission in the serving cell, the serving cell may stop transmission for only some UEs. The aforementioned some UEs may be, for example, UEs that have notified the PCI collision, UEs that are in the same beam as the UE, or high-altitude UEs. The serving cell may instruct handover only to the aforementioned some UEs. This, for example, can reduce the number of UEs that perform handover, thereby reducing the amount of signaling between base stations and between the UE and the base station.

[0230] As another example of stopping cell transmission, a conflicting cell may stop transmission. The UE may notify the serving cell of information about the PCI conflict. The serving cell may request the conflicting cell to stop cell transmission. The request may include information about the PCI conflict. The conflicting cell may use the information to instruct a UE served by the conflicting cell to perform a handover to another cell. The handover may be to another base station or to another cell within the same base station. The UE served by the conflicting cell may use the instruction to perform a handover to another cell. The conflicting cell may stop transmission of its own cell after the handover of the served UE is completed. For example, the conflicting cell may stop transmission of its own cell after receiving RRC reconfiguration signaling from the served UE notifying the completion of handover.

[0231] As another example of stopping transmissions in a conflicting cell, the conflicting cell may stop transmissions for only some UEs. The conflicting cell may stop transmissions for only some UEs. For example, the conflicting cell may stop transmissions for only some UEs in the same beam as the UE that notified the PCI conflict, or may stop transmissions for high-altitude UEs. The conflicting cell may instruct handovers for only some UEs. This may reduce the number of UEs that perform handovers, thereby reducing the amount of signaling between base stations and between the UE and the base station.

[0232] As another example of stopping cell transmission, arbitration regarding stopping cell transmission may be performed between a serving cell and a conflicting cell. This arbitration may be performed in the same manner as the arbitration regarding PCI change between a serving cell and a conflicting cell disclosed in the second embodiment. This enables, for example, flexible cell control according to the status of the communication system. Also, for example, it is possible to avoid complexity in the communication system.

[0233] As another example of stopping cell transmission, the AMF may determine a cell to stop transmission. The AMF may instruct the cell to stop transmission. The determination and / or instruction in the AMF may be performed in the same manner as the determination and / or instruction by the AMF regarding the PCI change between the serving cell and the conflicting cell disclosed in the second embodiment. This makes it possible to reduce, for example, the amount of signaling between base stations.

[0234] Another solution is disclosed. The transmit power of the cell is reduced. The UE may notify the serving cell of information about the PCI collision. The UE may include information about the received power from the cell where the PCI collision occurred in the notification. This allows, for example, the cell to appropriately control the amount of power reduction.

[0235] The serving cell may reduce its transmission power. The reduction in transmission power in the serving cell may be performed, for example, in the same manner as the PCI change in the serving cell disclosed in the second embodiment. The UE served by the serving cell may not perform random access processing with the serving cell after the transmission power in the serving cell is reduced. The UE served by the serving cell may continue communication with the serving cell even after the transmission power in the serving cell is reduced. This makes it possible to avoid complexity in the communication system, for example.

[0236] As another example of a reduction in the transmission power of a cell, a conflicting cell may reduce its transmission power. The reduction in transmission power in a conflicting cell may be performed, for example, in the same manner as the PCI change in a conflicting cell disclosed in the second embodiment. A transmission power reduction request transmitted from a serving cell to a conflicting cell may include information on the amount of power reduction. The serving cell may obtain, from the UE, information on the received power from a cell with which a PCI conflict has occurred, and use the information to determine the amount of power reduction. This makes it possible to flexibly control, for example, the amount of power reduction in a conflicting cell.

[0237] As another example of the reduction of the transmission power of a cell, arbitration regarding the reduction of the transmission power may be performed between a serving cell and a conflicting cell. The arbitration may be performed in the same manner as the arbitration regarding the PCI change between a serving cell and a conflicting cell disclosed in the second embodiment. This makes it possible to avoid complexity in the communication system, for example.

[0238] As another example of reducing the transmission power of a cell, the AMF may determine a cell to reduce its transmission power. The AMF may instruct the cell to reduce its transmission power. The determination and / or instruction in the AMF may be performed in the same manner as the determination and / or instruction by the AMF regarding the PCI change between a serving cell and a conflicting cell disclosed in the second embodiment. This makes it possible to avoid complexity in the communication system, for example.

[0239] The above solutions may be combined. For example, changing the PCI of a cell and stopping transmission of the cell may be combined. The decision to change the PCI of a cell and / or stopping transmission of the cell may be made by the serving cell, the conflicting cell, or the AMF. This may enable, for example, flexible operation of the communication system.

[0240] According to the second embodiment, it is possible to avoid PCI collisions in high-altitude UEs, and as a result, it is possible to prevent malfunctions in high-altitude UEs.

[0241] Variation 1 of Embodiment 2 In the second embodiment, an example is disclosed in which a UE, for example, a high-altitude UE, detects a PCI collision, but a base station, for example, a high-altitude base station, may also detect a PCI collision.

[0242] The base station may notify the cell of the detected PCI of information about the PCI collision. The notification may be performed, for example, using an inter-base station I / F (e.g., an Xn interface). The cell of the PCI may use the notification to arbitrate the PCI, for example, change the PCI and / or stop cell transmission.

[0243] As another example, the base station may notify the AMF of information about the detected PCI collision. The notification may be performed, for example, using the N2 interface. The AMF may use the notification to perform PCI arbitration. The AMF may instruct the conflicting cell to change its PCI or to stop cell transmission. This may, for example, reduce the amount of signaling in the interface between base stations.

[0244] This first modification of the second embodiment makes it possible to prevent PCI collisions between cells while suppressing an increase in the amount of signaling between a UE and a base station, thereby preventing erroneous reception of system information by a UE, for example, a high-altitude UE.

[0245] Embodiment 3 In SL communication, communication between a UE and a network via a relay has been proposed (see Non-Patent Document 29 (3GPP TR 23.703 V12.0.0)). A relay between a UE and a network may be referred to as a UE-to-network relay or a UE-to-network relay. In this disclosure, a UE that performs relaying between a UE and a network may be referred to as a relay UE.

[0246] For example, there may be a need to communicate not only between UEs within the coverage of a RAN node (e.g., gNB) but also between UEs that are farther away and the RAN node. In such cases, a method using a UE-to-NW relay may be considered. For example, communication between a gNB and a UE (sometimes referred to as a remote UE) may be performed via a relay UE. Communication between the gNB and the relay UE is performed via Uu, and communication between the relay UE and the remote UE is performed via PC5.

[0247] There is no disclosure of a communication method between a UE and a network via a relay UE in a 5G system. There is also no disclosure of a QoS flow for communication between a UE and a network via a relay UE or a method for setting up an SLRB. When communication is performed between a UE and a network via a relay UE, the issue is how to satisfy the QoS required for the service.

[0248] In the third embodiment, a method for solving such a problem will be disclosed.

[0249] Conventionally, in a 5G system, a PDU session is established between a UE and a NW in communication between the UE and the NW. However, in a UE-to-NW relay, communication between the UE and the NW is performed via a relay UE, so conventional methods cannot be applied. This paper discloses a PDU session when communication between a UE and a NW is performed via a relay UE.

[0250] A PDU session is established between the relay UE and the NW. A PDU session is established between the relay UE and a CN-side node. The CN-side node may be a UPF. A PDU session may be established between the relay UE and a data network. A PC5-S link is established between the relay UE and the remote UE. Communication is performed between the UE and the NW via the relay UE using the PDU session and the PC5-S link.

[0251] Establish a PDU session for relay between the relay UE and the CN node. Establish a PC5-S link between the relay UE and the remote UE. The remote UE notifies the relay UE of information about the remote UE. The remote UE may also notify the AMF or SMF of information about the remote UE. Specific examples of the information about the remote UE include a remote UE identifier and IP information. The IP information may be an IP address. Another specific example of the information about the remote UE may be information about the PC5-S link between the remote UE and the relay UE. The information about the PC5-S link may be, for example, a PC5-S link identifier, a source UE identifier, a destination UE identifier, PC5 QoS flow information, a PC5 QoS flow identifier, SLRB setting information, an SLRB identifier, or a combination of these.

[0252] The IP address of the remote UE may be IPv4, which can avoid the complexity of the device design. The IP address of the remote UE may be IPv6, which can accommodate a large number of UEs in the communication network.

[0253] The relay UE may store information about the remote UE. Also, the AMF / SMF may store information about the remote UE. The information about the remote UE may be associated with the relay UE. The information about the remote UE may be stored in association with the relay UE. The information about the remote UE may be associated with a PDU session established between the relay UE and the NW. The information about the remote UE may be stored in association with a PDU session established between the relay UE and the NW. For example, the information about the remote UE may be stored in the context of the relay UE. By associating the information about the remote UE with the relay UE or associating the information about the remote UE with a PDU session established between the relay UE and the NW, for example, the AMF / SMF can recognize that the PDU session is not simply a PDU session between the relay UE and the CN, but is a PDU session for relaying to the remote UE.

[0254] The AMF / SMF notifies the UPF of information about the remote UE. The UPF can also recognize the information about the remote UE. The information about the remote UE may be notified in association with the relay UE. The information about the remote UE may be notified in association with the PDU session established between the relay UE and the NW. By associating the information about the remote UE with the relay UE or the PDU session established between the relay UE and the NW, for example, the UPF can recognize that the PDU session is not simply a PDU session between the relay UE and the CN, but is a PDU session for relaying to the remote UE.

[0255] In this way, the PDU session between the relay UE and the NW is associated with the PC5-S link between the relay UE and the remote UE.

[0256] The relay UE, as a router for the remote UE, forwards the PC5-S link between the remote UE and the relay UE and the PDU session between the relay UE and the NW, and may use information about the remote UE for the forwarding.

[0257] In this way, data communication between the remote UE and the UPF becomes possible via the relay UE.

[0258] This document discloses QoS when establishing a relay PDU session between a relay UE and a CN node. A default QoS flow is set for the PDU session. A default QoS may be set for establishing the PDU session. Alternatively, a default QCI (QoS Class Identifier) ​​or 5QI (5G QoS Identifier) ​​may be set. Alternatively, a QoS for the relay UE may be set. A QoS for the relay UE may be used for establishing the PDU session. These QoS, QCI, or 5QI may be pre-configured. For example, they may be pre-configured in AMF / SMF. This makes it possible to establish a PDU session even if the QoS of a service communicated between the relay UE and the CN node is unknown. When service data is generated in a remote UE, the relay UE may not recognize the QoS required for the service. This method is effective in such cases.

[0259] FIG. 20 is a sequence diagram showing a first example of a method for communicating between a UE and a NW via a relay UE according to the third embodiment. In Step ST4101, the relay UE performs a process for establishing a PDU session between the gNB, the AMF / SMF, and the UPF, and establishes a PDU session between the relay UE and the UPF. The relay UE may perform the process for establishing the PDU session before performing relaying. The method described above may be applied to establish this PDU session. For example, a default QoS may be used to establish the PDU session. For example, a default QoS flow may be set for the PDU session.

[0260] In Step ST4102, a discovery process is performed between the remote UE and the relay UE to detect a data transmission destination. In this discovery process, the relay UE may notify information indicating that it has relay capability between the NW and the UE. By receiving this information, the remote UE can recognize that it is able to communicate with the NW via the relay UE.

[0261] In this discovery process, the remote UE may notify information indicating that it is searching for a relay UE between the NW and the UE. The remote UE may notify information requesting connection to the NW. The remote UE may notify information requesting relay to the NW. The remote UE may notify information indicating that the destination is the NW. By receiving this information, the relay UE can recognize that the remote UE is requesting connection to the NW via its own relay UE.

[0262] In Step ST4103, a process for establishing a PC5-S link is performed between the remote UE and the relay UE. The remote UE that has detected the relay UE for communication with the NW may perform a process for establishing a PC5-S link with the relay UE in Step ST4103. Through this process, a PC5-S link is established between the remote UE and the relay UE. In this process, the remote UE may notify information requesting connection to the NW, information requesting relay to the NW, or information indicating that the destination is the NW. The relay UE can recognize that the remote UE is requesting connection to the NW via its own relay UE.

[0263] In Step ST4104, AS configuration may be notified between the remote UE and the relay UE. The AS configuration may include, for example, an SLRB configuration for data communication or an SLRB identifier. The configuration of a PC5 QoS flow between the remote UE and the relay UE and the configuration of an SLRB to which the PC5 QoS flow is mapped may be performed using the QoS required for the service communicated between the remote UE and the NW. For example, the remote UE derives QoS-related information corresponding to the generated service. The remote UE may configure a PC5 QoS flow and a PC5 QoS flow identifier from the QoS-related information. The remote UE also configures an SLRB to which the PC5 QoS flow is mapped. The remote UE may set an identifier for the SLRB configuration. In this way, PC5 communication that satisfies the QoS required for the service can be achieved.

[0264] The mapping information between QoS and SLRB configuration may be configured in advance in the remote UE. When the remote UE is out of the coverage of the gNB, the remote UE may configure the SLRB using the mapping information between QoS and SLRB configuration configured in advance in the remote UE. When the remote UE is within the coverage of the gNB, the remote UE may receive the mapping information between QoS and SLRB configuration broadcast from the gNB. Alternatively, the remote UE may use the SLRB configuration individually notified by the gNB via RRC signaling. In this case, the remote UE may notify the gNB of QoS-related information of the generated service. The gNB may configure the SLRB using the QoS-related information of the service received from the remote UE. The gNB disclosed herein may be different from the gNB connecting to the relay UE.

[0265] The QoS-related information may include PC5 QoS parameters (sometimes referred to simply as QoS parameters, with PC5 omitted). The PC5 QoS parameters may include, for example, PQI (see Non-Patent Document 26 (TS23.287 V16.2.0)). The QoS-related information may also include QoS characteristics (see Non-Patent Document 26 (TS23.287 V16.2.0)). The PC5 QoS parameters and QoS characteristics may be referred to as a QoS profile.

[0266] The QoS-related information may include a PC5 QoS flow identifier (PQI), which may be used to identify the QoS flow established by the remote UE for data communication with the relay UE over PC5.

[0267] The process for establishing a PC5-S link may include a process for establishing a PC5-S link from a remote UE to a relay UE, or a process for establishing a PC5-S link from a relay UE to a remote UE, or a process for establishing a PC5-S link from a remote UE to a relay UE and from a relay UE to a remote UE.

[0268] After the PC5-S link establishment process from the remote UE to the relay UE and the process of notifying the relay UE of the AS setting for SL communication, a PC5-S link establishment process from the relay UE to the remote UE and the process of notifying the relay UE of the AS setting for SL communication may be performed.

[0269] After processing to establish a PC5-S link from the remote UE to the relay UE and from the relay UE to the remote UE, processing may be performed to configure an AS for SL communication from the remote UE to the relay UE and to notify the remote UE of the AS configuration for SL communication from the relay UE.

[0270] This enables two-way SL communication, which allows communication from the remote UE to the NW and communication from the NW to the remote UE.

[0271] Information requesting PC5-S link establishment may be provided. The remote UE may notify the relay UE of information requesting PC5-S link establishment from the relay UE to the remote UE. The relay UE, upon receiving the information, initiates a PC5-S link establishment process to the remote UE. The notification may be performed using PC5-S signaling from the remote UE to the relay UE. The notification may be performed during the PC5-S link establishment process from the remote UE to the relay UE. This enables the remote UE to initiate a bidirectional PC5-S link establishment process. When a service with a bidirectional network occurs in the remote UE, the remote UE, which recognizes the service as bidirectional, can initiate a bidirectional PC5-S link establishment process.

[0272] The relay UE may start a PC5-S link establishment process to the remote UE when it receives information requesting connection to the NW from the remote UE. In this way, when the remote UE connects to the NW, a bidirectional PC5-S link establishment process is executed between the remote UE and the relay UE. Since it is not necessary to notify information requesting PC5-S link establishment, it is possible to reduce the signaling load and avoid complicated processing.

[0273] As mentioned above, when service data is generated in the remote UE, the relay UE may not recognize the QoS required for the service. In such a case, the relay UE may encounter a problem in that it cannot set up an SLRB for SL communication between the relay UE and the remote UE.

[0274] A method for solving such problems is disclosed.

[0275] A default QoS is set for the relay UE to use for SL communication with the remote UE. Alternatively, a default QCI or 5QI may be set. The relay UE sets up an SLRB with the remote UE using the default QoS. An identifier for the SLRB setting may be set. The relay UE may set up a PC5 QoS flow with the remote UE using the default QoS. A PC5 QoS flow identifier may be set. The relay UE notifies the remote UE of the set SLRB setting. An SLRB identifier may be notified. A PC5 QoS flow may be notified. A PC5 QoS flow identifier may be notified. These may be notified by being included in the AS setting. In this way, PC5 communication from the relay UE to the remote UE is enabled.

[0276] These QoS, QCI, or 5QI may be statically determined in advance by a standard, or may be set in advance in the relay UE, or may be set in advance in the relay UE from the network. These QoS, QCI, or 5QI may be provided to the relay UE, for example, in a PDU session establishment process between the relay UE and the network.

[0277] A default PC5 QoS flow may be set by the relay UE for SL communication with the remote UE. A default SLRB configuration may be set by the relay UE for SL communication with the remote UE. The relay UE uses the default QoS flow and / or the default SLRB configuration to set a PC5 QoS flow with the remote UE, set a PC5 QoS flow identifier, and set an SLRB to which the PC5 QoS flow is mapped. An identifier for the SLRB configuration may also be set. In this way, PC5 communication from the relay UE to the remote UE is enabled.

[0278] It has been disclosed that a relay UE sets a default QoS to be used for SL communication with a remote UE. The SL communication may be service data communication or signaling communication. For example, a default QoS or default SLRB configuration may be set for PC5-S signaling communication. A default SLRB configuration may be used for PC5-S signaling communication from the relay UE to the remote UE. A default QoS or default SLRB configuration may be set for RRC signaling communication. A default SLRB configuration may be used for RRC signaling communication from the relay UE to the remote UE. This enables PC5-S signaling and RRC signaling from the relay UE to the remote UE.

[0279] Default QoS and default SLRB settings may be provided for signaling from the remote UE to the relay UE. This enables signaling from the remote UE to the relay UE. The default QoS and default SLRB settings for signaling from the remote UE to the relay UE may be the same as the default QoS and default SLRB settings for signaling from the relay UE to the remote UE. This simplifies the SLRB setting process and signaling process.

[0280] Another method is disclosed.

[0281] The remote UE notifies the relay UE of QoS related information. The relay UE uses the QoS related information received from the remote UE to set up an SLRB between the relay UE and the remote UE. An identifier for the SLRB setting may be set. The relay UE may use the QoS related information received from the remote UE to set up a PC5 QoS flow between the relay UE and the remote UE. A PC5 QoS flow identifier may be set. The relay UE notifies the remote UE of the set SLRB setting. An SLRB identifier may be notified. A PC5 QoS flow may be notified. A PC5 QoS flow identifier may be notified. These may be notified by being included in the AS setting. In this way, PC5 communication from the relay UE to the remote UE is enabled.

[0282] The remote UE may notify the relay UE of QoS-related information of the service generated at the remote UE. The relay UE may use the QoS-related information of the service generated at the remote UE received from the remote UE to perform SLRB setup between the relay UE and the remote UE. This enables SL communication over PC5 that is suitable for the QoS of the service generated at the remote UE.

[0283] The remote UE may notify the relay UE of service-related information of a service generated at the remote UE. The relay UE may establish a PC5-S link with the remote UE using the service-related information received from the remote UE. The relay UE may derive QoS-related information using the service-related information received from the remote UE. The relay UE may configure an SLRB with the remote UE using the derived QoS-related information. The relay UE may set an identifier for the SLRB configuration. The relay UE may configure a PC5 QoS flow with the remote UE using the derived QoS-related information. The relay UE may set a PC5 QoS flow identifier. In this way, PC5 communication from the relay UE to the remote UE is enabled.

[0284] The service-related information may include a service type (e.g., PSID, ITS-AID, etc.), an identifier of the remote UE, etc. The service-related information may be associated with remote UE-related information. The service-related information may include QoS-related information or information regarding the QoS required for the service.

[0285] The QoS-related information may be notified from the remote UE to the relay UE using PC5-S signaling, or may be notified during the PC5-S link establishment process from the remote UE to the relay UE, thereby enabling early notification.

[0286] The QoS-related information may be notified from the remote UE to the relay UE using RRC signaling. The information may be included in the AS configuration from the remote UE to the relay UE and notified. Since the AS configuration for communication via PC5 between the remote UE and the relay UE is performed after the relay UE performs the configuration for the remote UE, it is possible to reduce malfunctions in the process for communication via PC5 between the remote UE and the relay UE.

[0287] Another method is disclosed.

[0288] The remote UE notifies the relay UE of PC5 QoS flow information. It may also notify the PC5 QoS flow identifier. The remote UE may notify the relay UE of SLRB configuration. It may also notify the SLRB identifier. The SLRB configuration may not only notify parameters required by both the transmitting and receiving sides, but also parameters required only by the transmitting side. This enables SLRB configuration when the relay UE is the transmitting side. In addition, the SLRB configuration may notify parameters required only by the receiving side. The relay UE can recognize the parameters required by the remote UE. The relay UE uses the PC5 QoS flow information and / or SLRB configuration received from the remote UE to configure the PC5 QoS flow and / or SLRB between it and the remote UE.

[0289] The relay UE may notify the remote UE that the PC5 QoS flow and / or SLRB configuration received from the remote UE has been configured for communication from the relay UE to the remote UE via PC5. Alternatively, the relay UE may notify the remote UE of the configured PC5 QoS flow and / or SLRB configuration. This information may be notified by including it in the AS configuration. In this way, PC5 communication from the relay UE to the remote UE can be enabled.

[0290] The remote UE may notify the relay UE of PC5 QoS flow information set from the QoS of the service generated at the remote UE. The remote UE may notify the relay UE of an SLRB configuration for mapping the PC5 QoS flow. The relay UE may perform SLRB configuration between the relay UE and the remote UE using the PC5 QoS flow information and / or the SLRB configuration received from the remote UE. This enables SL communication over PC5 that is suitable for the QoS of the service generated at the remote UE.

[0291] The method for notifying the relay UE of the PC5 QoS flow information and / or SLRB setting from the remote UE may be the same as the method described above, and the same effect can be obtained.

[0292] Another method is disclosed.

[0293] The relay UE notifies the gNB of QoS-related information. The relay UE may also notify the gNB of service-related information. The gNB configures an SLRB using the QoS-related information received from the relay UE. The relay UE configures an SLRB for communication between remote UEs via PC5 using the SLRB configuration received from the gNB. The relay UE notifies the remote UE of the configured SLRB configuration. An SLRB identifier may also be notified. These may also be included in the AS configuration and notified. In this way, PC5 communication from the relay UE to the remote UE is enabled.

[0294] Notification from the relay UE to the gNB and notification from the gNB to the relay UE may be performed using RRC signaling over Uu.

[0295] The QoS-related information notified by the relay UE to the gNB may be the default QoS as described above, or may be the QoS-related information received from the remote UE as described above, or may be the QoS-related information of a service generated in the remote UE as received from the remote UE. The service-related information notified by the relay UE to the gNB may be the service-related information of a service generated in the remote UE as described above. By using the QoS-related information of the service generated in the remote UE, the gNB can configure the SLRB for PC5 communication from the relay UE to the remote UE to be suitable for the QoS required for the service.

[0296] In Step ST4105, the remote UE notifies the AMF / SMF of remote UE-related information via the relay UE and the gNB. In Step ST4106, the AMF / SMF stores the remote UE-related information in the context of the relay UE to associate the information with the relay UE. In Step ST4107, the AMF / SMF notifies the UPF of the remote UE-related information. The remote UE-related information may be notified in association with the relay UE. In this way, the UPF can recognize that the PDU session established with the relay UE is for relaying with the remote UE. Therefore, for example, when DL data to the remote UE occurs, the UPF can transmit the DL data to the remote UE via the relay UE.

[0297] In Step ST4108, UL data communication is enabled between the remote UE and the UPF, and in Step ST4109, DL data communication is enabled between the UPF and the remote UE.

[0298] When the PC5-S link between the remote UE and the relay UE is released (or may be disconnected), the relay UE may initiate a process to release (or may be disconnected) the PDU session. This eliminates the need to maintain the PDU session when no service data is generated between the remote UE and the NW. This can eliminate wasteful resource usage in the relay UE, gNB, and CN nodes.

[0299] When the PDU session between the relay UE and the CN node is released, the relay UE may initiate a process to release the PC5-S link between the remote UE and the relay UE. The relay UE may notify the remote UE of information indicating that the PDU session has been released. Upon receiving the information, the remote UE may perform a process to release the PC5-S link with the relay UE. In this way, if the PDU session between the relay UE and the CN is released for some reason, there is no need to maintain the PC5-S link. This can eliminate waste of resource usage in the remote UE and the relay UE.

[0300] When the PC5-S link between the remote UE and the relay UE is released, the relay UE may maintain the PDU session, so that communication between the remote UE and the network can be resumed quickly if service data is generated again at the remote UE.

[0301] When the PDU session between the relay UE and the CN node is released, the PC5-S link between the remote UE and the relay UE may be maintained. If the PDU session is re-established, communication between the remote UE and the NW will be possible sooner.

[0302] PDU session release request information may be provided. The remote UE may notify the relay UE of the PDU session release request information. The remote UE may notify the AMF / SMF of the PDU session release request information. When the service is terminated at the remote UE, the remote UE notifies the relay UE or the AMF / SMF via the relay UE and the gNB of the PDU session release request information. The relay UE that receives the information performs PDU session release. Alternatively, the AMF / SMF that receives the information may perform PDU session release.

[0303] The remote UE that has notified the relay UE or AMF / SMF of the PDU session release request information may perform PC5-S link release processing. For example, if the PC5-S link is released but the PDU session is maintained because service data will soon be generated again, the remote UE performs PC5-S link release processing without sending PDU session release request information. If the remote UE wants to release the PC5-S link and PDU session to terminate the service, it sends PDU session release request information and performs PC5-S link release processing. In this way, the PC5-S link and PDU session can be released as appropriate.

[0304] Although PDU session release request information has been disclosed, PDU session maintenance request information requesting maintenance of a PDU session may also be used. Alternatively, information indicating a PDU session release request or maintenance request may be used.

[0305] Another method for solving the above-mentioned problems is disclosed.

[0306] After the PC5-S link is established between the remote UE and the relay UE, a PDU session for relay is established between the relay UE and the CN node. The remote UE notifies the relay UE of service-related information. After the PC5-S link is established between the remote UE and the relay UE, or during the PC5-S link establishment process between the remote UE and the relay UE, the remote UE may notify the relay UE of service-related information.

[0307] The relay UE notifies the CN node of the service-related information. Before the establishment of a relay PDU session between the relay UE and the CN node, or during the relay PDU session establishment process between the relay UE and the CN node, the relay UE may notify the CN node of the service-related information.

[0308] The service-related information may be used to establish a PDU session for relay between the relay UE and the CN node. The relay UE may establish a PDU session for relay between the relay UE and the CN node using the service-related information notified from the remote UE. The CN node may establish a PDU session for relay between the relay UE and the CN node using the service-related information notified from the relay UE.

[0309] In this way, a PDU session suitable for a service communicated between the remote UE and the NW can be established between the relay UE and the CN node. A PDU session can be established between the relay UE and the CN node according to the QoS required for the service communicated between the remote UE and the NW. In communication between the remote UE and the NW via the relay UE, communication according to the QoS required for the service becomes possible.

[0310] Fig. 21 is a sequence diagram showing a second example of a method for communicating between a UE and a NW via a relay UE according to the third embodiment. Fig. 21 discloses a method for establishing a PDU session for relay between a relay UE and a CN node after establishing a PC5-S link between a remote UE and a relay UE. In Fig. 21, steps common to Fig. 20 are assigned the same step numbers, and common explanations will be omitted.

[0311] First, a PC5-S link establishment process is performed between the remote UE and the relay UE. In Step ST4102, a discovery process is performed between the remote UE and the relay UE to detect a data transmission destination. In Step ST4103, a process for establishing a PC5-S link is performed between the remote UE and the relay UE. In Step ST4104, an AS setting may be notified between the remote UE and the relay UE. Through these processes, communication according to the QoS required for the service becomes possible in the PC5 between the remote UE and the relay UE.

[0312] In Step ST4201, the remote UE notifies the relay UE of service-related information (QoS-related information of the service is illustrated in the example of FIG. 21). The relay UE that has received the service-related information can recognize the QoS-related information of the service with which the remote UE communicates. The relay UE notifies the gNB of the service-related information. The gNB that has received the service-related information can recognize the QoS-related information of the service with which the remote UE communicates. The gNB notifies the AMF / SMF of the service-related information. The AMF / SMF that has received the service-related information can recognize the QoS-related information of the service with which the remote UE communicates.

[0313] In Step ST4202, the relay UE performs a PDU session establishment procedure among the gNB, AMF / SMF, and UPF, and establishes a PDU session between the relay UE and the UPF. The AMF / SMF may notify the UPF of service-related information. The AMF / SMF may notify the UPF of service-related information in the PDU session establishment procedure. Information related to the service may be used to establish the PDU session. For example, a QoS flow may be configured for the PDU session using information related to the QoS required for the service. For example, a QoS flow may be configured to satisfy the QoS required for the service as the QoS for the PDU session. For example, a QoS flow may be configured so that the required values ​​of each parameter of the 5QI for the PDU session are included in the values ​​of each parameter of the PC5 5QI (sometimes referred to as PQI), which is the PC5 5QI required for the service. The relay UE may perform the PDU session establishment procedure before performing relaying.

[0314] The relay UE may be provided with mapping information between the QoS for the PDU session and the PC5 QoS from the NW. For example, the CN node notifies the relay UE via the gNB of information associating the PQI of the PDU session with the PQI of the PC5 for mapping the PDU session and the PC5-S link. This information may be notified before the PDU session establishment process or during the PDU session establishment process. Alternatively, the mapping information may be notified after the PDU session is established. For example, the mapping information may be used when modifying the PDU session.

[0315] The correspondence information between the QoS for the PDU session and the QoS of the PC5 may be statically determined in advance by a standard, etc. Since signaling of this information is not required, the signaling load can be reduced.

[0316] In a 5G system, both the PDU session between a UE and a CN node and the PC5 between UEs are QoS flow-based. This requires the configuration of QoS flows / PC5 QoS flows and the configuration of an SLRB that maps the PC5 QoS flows. For example, by using the aforementioned mapping information in these configurations, it becomes possible to establish a PDU session appropriate for the service between the relay UE and the CN node as well as communication between the remote UE and the relay UE. This enables communication between the remote UE and the NW via the relay UE according to the QoS required for the service.

[0317] In Step ST4201 or Step ST4202, the remote UE may notify the relay UE, the gNB, the AMF / SMF, or the UPF of the remote UE-related information together with the service-related information. The service-related information and the remote UE-related information may be associated with each other. In this way, it is possible to reduce the amount of signaling required between nodes.

[0318] The PDU session may be modified with service related information, for example to set up QoS flows with information related to the QoS required for the service.

[0319] For example, a PDU session is established between the relay UE and the CN using default QoS. Then, a PC5-S link is established between the remote UE and the relay UE. After the PC5-S link is established between the remote UE and the relay UE, or while the remote UE and the relay UE are performing the PC5-S link establishment process, the remote UE may notify the relay UE of service-related information. The relay UE notifies the CN node of the service-related information. Before the PDU session for relay between the relay UE and the CN node is established, or while the PDU session for relay between the relay UE and the CN node is performing the PDU session establishment process for relay, the relay UE may notify the CN node of the service-related information.

[0320] Modifying a PDU session for relay between the relay UE and the CN node. The service-related information may be used to modify the PDU session for relay between the relay UE and the CN node. The relay UE may modify the PDU session for relay between the relay UE and the CN node using the service-related information notified from the remote UE. The CN node may modify the PDU session for relay between the relay UE and the CN node using the service-related information notified from the relay UE.

[0321] For example, a PDU session may be established between the relay UE and the CN using default QoS, and after data communication is performed between the remote UE and the NW via the relay UE using the PDU session, the PDU session for relay between the relay UE and the CN node may be modified as described above, allowing communication to be performed that is more suited to the QoS required for the service.

[0322] The remote UE may notify the relay UE, the gNB, the AMF / SMF, or the UPF of a PDU session modification request. The remote UE may notify service-related information in the PDU session modification request. In this way, the remote UE can request the PDU session modification.

[0323] For example, the remote UE may monitor QoS-related information. The remote UE may monitor QoS-related information of a service communicated with the NW. Alternatively, the remote UE may monitor QoS-related information of a service communicated with the relay UE via PC5. The monitored QoS-related information may be QoS parameters or QoS characters. In this way, the remote UE can evaluate the QoS of a service communicated with the NW.

[0324] For example, if the remote UE determines that the monitored QoS-related information does not satisfy the QoS-related information required for the service communicated with the NW, it may execute the aforementioned PDU session modification request. The remote UE includes the service-related information in the PDU session modification request and notifies the relay UE, gNB, AMF / SMF, or UPF of the PDU session modification request. The AMF / SMF that receives the PDU session modification request modifies the PDU session between the relay UE and the UPF using the service-related information. This enables communication that is more suitable for the QoS required for the service.

[0325] The relay UE may notify the gNB, or the AMF / SMF, or the UPF, of a PDU session modification request. The relay UE may notify the PDU session modification request by including service-related information in the PDU session modification request. In this way, the relay UE can request the PDU session modification.

[0326] For example, the relay UE may monitor QoS-related information. The relay UE may monitor QoS-related information of services communicated between the relay UE and the NW. Alternatively, the relay UE may monitor QoS-related information of services communicated between the relay UE and the remote UE via PC5.

[0327] For example, if the relay UE determines that the monitored QoS-related information does not satisfy the QoS-related information required for the service communicated between the relay UE and the NW, it may execute the above-mentioned PDU session modification request. The relay UE includes the service-related information in the PDU session modification request and notifies the gNB, AMF / SMF, or UPF of the PDU session modification request. The AMF / SMF that receives the PDU session modification request modifies the PDU session between the relay UE and the UPF using the service-related information. This enables communication that is more suitable for the QoS required for the service.

[0328] The gNB may notify the AMF / SMF or UPF of a PDU session modification request. The gNB may notify the PDU session modification request by including service-related information in the PDU session modification request. In this way, the gNB can request the modification of the PDU session.

[0329] For example, the gNB may monitor QoS-related information. The gNB may monitor QoS-related information of services communicated between the NW.

[0330] For example, if the gNB determines that the monitored QoS-related information does not satisfy the QoS-related information required for the service communicated between the gNB and the NW, the gNB may execute the PDU session modification request. The gNB includes the service-related information in the PDU session modification request and notifies the AMF / SMF or UPF of the PDU session modification request. The AMF / SMF that receives the PDU session modification request modifies the PDU session between the relay UE and the UPF using the service-related information. This enables communication that is more suitable for the QoS required for the service.

[0331] The UPF may notify the AMF / SMF of a PDU session modification request. The AMF / SMF that receives the PDU session modification request may modify the PDU session using the service-related information received from the remote UE.

[0332] For example, the UPF may monitor QoS related information of the services communicated to and from the relay UE or the remote UE.

[0333] For example, if the UPF determines that the monitored QoS-related information does not satisfy the QoS-related information required for the service communicated between the relay UE or the remote UE, the UPF may execute the PDU session modification request. The UPF notifies the AMF / SMF of the PDU session modification request. The AMF / SMF that receives the PDU session modification request modifies the PDU session between the relay UE and the UPF using the service-related information. This enables communication that is more suitable for the QoS required for the service.

[0334] Fig. 22 is a sequence diagram showing a method for modifying a PDU session for relay between a relay UE and a CN node according to embodiment 3. In Fig. 22, the same step numbers are assigned to steps common to Fig. 20 and Fig. 21, and common explanations will be omitted.

[0335] In Step ST4101, the relay UE performs a PDU session establishment process between the gNB, the AMF / SMF, and the UPF, and establishes a PDU session between the relay UE and the UPF. A default QoS may be used to establish the PDU session. For example, a default QoS flow may be set for the PDU session.

[0336] A PC5-S link establishment process is performed between the remote UE and the relay UE. In Step ST4102, a discovery process is performed between the remote UE and the relay UE to detect a data transmission destination. In Step ST4103, a process is performed to establish a PC5-S link between the remote UE and the relay UE. In Step ST4104, AS settings may be notified between the remote UE and the relay UE. Through these processes, communication according to the QoS required for the service becomes possible in the PC5 between the remote UE and the relay UE.

[0337] In Step ST4301, the remote UE notifies the relay UE of remote UE-related information and service-related information. The relay UE that has received the service-related information can recognize QoS-related information of the service with which the remote UE communicates, along with the remote UE-related information. The relay UE notifies the gNB of the service-related information. The gNB that has received the service-related information can recognize QoS-related information of the service with which the remote UE communicates, along with the remote UE-related information. The gNB notifies the AMF / SMF of the service-related information. The AMF / SMF that has received the service-related information can recognize QoS-related information of the service with which the remote UE communicates, along with the remote UE-related information.

[0338] In Step ST4302, the relay UE performs a PDU session modification process between the gNB, AMF / SMF, and UPF, and modifies the PDU session between the relay UE and the UPF. The AMF / SMF may notify the UPF of service-related information. Information related to the service may be used to modify the PDU session. For example, a QoS flow may be set for the PDU session using information related to the QoS required for the service. The PDU session for relay between the relay UE and the CN node may be modified using the service-related information notified from the remote UE. The CN node may modify the PDU session for relay between the relay UE and the CN node using the service-related information notified from the relay UE.

[0339] In this way, the PDU session between the relay UE and the CN node can be modified to be more suitable for the service, and in communication between the remote UE and the NW via the relay UE, communication more suitable for the QoS required for the service becomes possible.

[0340] As mentioned above, the relay UE does not generate service data. Therefore, how to configure the RB used for relay communication between the relay UE and the gNB becomes an issue. A method for solving this issue is disclosed. A default QoS is set. The default QoS may be the same as the default QoS used to establish a PDU session between the relay UE and the CN node. The default QoS may be used to configure the RB.

[0341] Alternatively, a default RB may be provided. Alternatively, a RB for relaying between the relay UE and the gNB may be provided. When service data is generated in a remote UE, the relay UE may not recognize the QoS required for the service. This method is effective in such cases.

[0342] In the above-described method, a PDU session is established between the relay UE and the NW. Here, another method is disclosed.

[0343] A PDU session may be established between the remote UE and the NW. The remote UE may perform a PDU session establishment procedure with the CN node. Alternatively, the CN node may perform a PDU session establishment procedure with the remote UE. The establishment of a PDU session between the remote UE and the NW is performed via a relay UE.

[0344] Before establishing a PDU session between the remote UE and the network, a PC5-S link may be established between the remote UE and the relay UE, and signaling required for the PDU session establishment process between the remote UE and the network may be performed using the PC5-S link.

[0345] The remote UE may notify the relay UE of service-related information when establishing a PC5-S link. The remote UE may notify the relay UE, the gNB, or the CN node of the service-related information during the PDU session establishment process.

[0346] By establishing a PDU session between the remote UE and the NE, it is possible to establish a PDU session that is suitable for the QoS required for the service generated by the remote UE, and communication that is more suitable for the service can be performed between the remote UE and the NW.

[0347] When a remote UE is within the coverage of a gNB, it may prioritize connection with the gNB. The remote UE connects to the NW via the gNB. When the remote UE is not within the coverage of the gNB, it connects to the gNB via a relay UE. The remote UE connects to the NW via the relay UE and the gNB. By prioritizing connection to the gNB in ​​this way, the remote UE can access the NW early when it is within the coverage of the gNB.

[0348] Another method will be disclosed. When a relay UE that can connect to a gNB is found, connection with the gNB via the relay UE may be prioritized. The remote UE connects to the gNB via the relay UE. The remote UE connects to the NW via the relay UE and the gNB. When the remote UE cannot find a relay UE that can connect to the NW and is within the coverage of the gNB, it connects to the gNB. The remote UE connects to the NW via the gNB. By prioritizing connection with the relay UE when a relay UE is found in this way, the remote UE can access the NW early even if it is not within the coverage of the gNB.

[0349] Another method is disclosed. When a remote UE is within the coverage of a gNB, and the remote UE finds a relay UE that can connect to the gNB, and predetermined conditions are met, connection to the gNB via the relay UE may be prioritized. The remote UE connects to the gNB via the relay UE. The remote UE connects to the NW via the relay UE and the gNB. If the predetermined conditions are not met, the remote UE connects to the gNB. The remote UE connects to the NW via the gNB. The predetermined conditions include, for example, received power, received quality, distance, and congestion level of SL resources.

[0350] For example, if the received power from the relay UE is greater than a predetermined threshold, connection with the relay UE may be prioritized. For example, if the received power from the relay UE is greater than the received power from the gNB, connection with the relay UE may be prioritized. The predetermined condition and / or threshold may be statically determined by a standard, or may be semi-statically or dynamically notified by the gNB or CN node, or a combination of these. This makes it possible to flexibly set whether to connect to the NW via a gNB or via a relay UE. Appropriate settings can be made depending on radio wave propagation conditions, the positional relationship between the remote UE and the relay UE, and the congestion status of SL resources. As a result, it becomes possible to satisfy the QoS required for the service.

[0351] By using the method disclosed in the third embodiment, communication between a UE and a network via a relay UE in a 5G system becomes possible. When communication is performed between a UE and a network via a relay UE, the QoS required for the service can be satisfied.

[0352] Variation 1 of embodiment 3 Another method for configuring an SLRB for mapping service data between a remote UE and a relay UE is disclosed.

[0353] The remote UE acquires the SLRB configuration between the remote UE and the relay UE via the relay UE. The remote UE acquires the SLRB configuration between the remote UE and the relay UE from the gNB to which the relay UE is connected.

[0354] The remote UE notifies the relay UE of service-related information. The relay UE notifies the gNB to which it is connected. The gNB derives an SLRB configuration for mapping service data between the remote UE and the relay UE. The gNB may derive the SLRB configuration using the service-related information received from the relay UE. The gNB notifies the relay UE of the derived SLRB configuration. The gNB may notify the derived SLRB configuration in association with the service-related information. The information may indicate which service the SLRB is configured for. The notification from the gNB to the relay UE may be performed using dedicated signaling or dedicated RRC signaling. The relay UE notifies the remote UE of the SLRB configuration and information indicating which service the SLRB is configured for. The remote UE configures an SLRB for mapping service data between the remote UE and the relay UE using the received SLRB configuration.

[0355] The remote UE notifies the relay UE of an SLRB configuration for a service to be communicated between the remote UE and the relay UE. The remote UE may notify the SLRB configuration in association with service-related information. The information may indicate which service the SLRB configuration is for, for example, information indicating which QoS flow the SLRB configuration is for. The relay UE uses the received SLRB configuration to configure an SLRB for mapping service data between the remote UE and the relay UE.

[0356] The relay UE may notify the remote UE of an SLRB configuration for a service communicated between the remote UE and the relay UE, and then set up an SLRB for mapping the service data between the remote UE and the relay UE. The remote UE sets up an SLRB for mapping the service data between the relay UE and the relay UE using the received SLRB configuration. The relay UE can recognize which service data the SLRB configuration is for using the service-related information, so it can set up an SLRB for mapping the service data between the relay UE and the remote UE even if it is not notified of the SLRB configuration from the remote UE.

[0357] This makes it possible to configure an SLRB for mapping service data between a remote UE and a relay UE. For example, even if a remote UE is outside the coverage area of ​​a gNB, it can obtain the SLRB configuration from the gNB via the relay UE. The processing load on the remote UE can be reduced by having the gNB to which the relay UE is connected configure the SLRB for the remote UE. In addition, it becomes possible to uniformly control the SLRB configuration of multiple remote UEs that perform PC5 communication with relay UEs under the gNB.

[0358] Figure 23 is a sequence diagram showing an example of a method in which a remote UE acquires an SLRB configuration between the remote UE and the relay UE from a gNB to which the relay UE is connected, in accordance with Variation 1 of Embodiment 3. Figure 23 discloses an example in which communication is performed between the remote UE and the NW via the relay UE. In Figure 23, steps common to those in Figure 21 are assigned the same step numbers, and common explanations will be omitted.

[0359] First, a PC5-S link establishment process is performed between the remote UE and the relay UE. In Step ST4102, a discovery process is performed between the remote UE and the relay UE to detect a data transmission destination. In Step ST4103, a process for establishing a PC5-S link is performed between the remote UE and the relay UE. In Step ST4104, an AS configuration may be notified between the remote UE and the relay UE. In the AS configuration in Step ST4104, the SLRB configuration used for data communication between the remote UE and the relay UE is not yet notified.

[0360] In Step ST4201, the remote UE notifies the relay UE of service-related information. The relay UE that has received the service-related information can recognize QoS-related information of the service with which the remote UE communicates. The relay UE notifies the gNB of the service-related information. The gNB that has received the service-related information can recognize QoS-related information of the service with which the remote UE communicates. The gNB notifies the AMF / SMF of the service-related information. The AMF / SMF that has received the service-related information can recognize QoS-related information of the service with which the remote UE communicates.

[0361] In Step ST4401, the gNB configures an SLRB for mapping a service using QoS-related information of the service. In Step ST4402, the gNB notifies the relay UE of the derived SLRB configuration. The gNB may notify the derived SLRB configuration in association with service-related information. The gNB may notify information indicating which service the SLRB configuration is for, for example, information indicating which QoS flow the SLRB configuration is for. The relay UE notifies the remote UE of the SLRB configuration derived by the gNB. The relay UE may notify the SLRB configuration in association with service-related information. The relay UE may notify information indicating which service the SLRB configuration is for, for example, information indicating which QoS flow the SLRB configuration is for. The remote UE configures an SLRB for mapping service data between the remote UE and the relay UE using the received SLRB configuration.

[0362] In Step ST4403, the remote UE notifies the relay UE of an SLRB configuration for a service for communication between the remote UE and the relay UE. The remote UE may notify the SLRB information in association with service-related information. The information may indicate which service the SLRB configuration is for, for example, information indicating which QoS flow the SLRB configuration is for. The relay UE uses the received SLRB configuration to configure an SLRB for mapping service data between the relay UE and the remote UE.

[0363] This allows the gNB to which the relay UE is connected to set up an SLRB for communicating service data in communication between the remote UE and the relay UE on PC5. In communication between the remote UE and the NW via the relay UE, communication according to the QoS required for the service becomes possible.

[0364] Another method is disclosed.

[0365] The relay UE sets up an SLRB between the remote UE and the relay UE. The remote UE obtains the SLRB configuration between the remote UE and the relay UE from the relay UE.

[0366] The gNB broadcasts SLRB configuration and mapping information between QoS-related information and the SLRB configuration. The SLRB configuration and mapping information between QoS-related information and the SLRB configuration may be for relay use. Broadcasting the configuration and information for the relay enables separate handling from SLRB configuration for direct communication between UEs served by a normal gNB. The relay UE receives the SLRB configuration and mapping information between QoS-related information and the SLRB configuration broadcast from the gNB. The relay UE configures an SLRB between the remote UE and the relay UE using the QoS-related information received from the remote UE, the SLRB configuration received from the gNB, and the mapping information between QoS-related information and the SLRB configuration.

[0367] The gNB may notify the relay UE of the SLRB configuration and mapping information between the QoS-related information and the SLRB configuration by dedicated signaling. The gNB may notify the relay UE of the SLRB configuration and mapping information between the QoS-related information and the SLRB configuration by RRC signaling. The relay UE configures the SLRB between the remote UE and the relay UE using the QoS-related information received from the remote UE, the SLRB configuration received from the gNB, and the mapping information between the QoS-related information and the SLRB configuration.

[0368] The relay UE notifies the remote UE of the SLRB configuration between the remote UE and the relay UE. The remote UE configures the SLRB between the remote UE and the relay UE using the SLRB configuration received from the relay UE. The relay UE also configures the SLRB between the remote UE and the relay UE using the SLRB configuration configured for service data communication with the remote UE.

[0369] This enables the configuration of an SLRB for mapping service data between a remote UE and a relay UE. For example, even when a remote UE is outside the coverage of a gNB, the remote UE can obtain an SLRB configuration from the gNB via the relay UE. Furthermore, even when the relay UE is in, for example, an RRC_Idle state or an RRC_Inactive state, the relay UE can configure an SLRB using information broadcast from the gNB. Furthermore, even when the relay UE is in, for example, an RRC_Connected state, the relay UE can configure an SLRB using information notified by dedicated signaling from the gNB.

[0370] Fig. 24 is a sequence diagram showing an example of a method in which a relay UE sets up an SLRB between a remote UE and a relay UE, according to Modification 1 of Embodiment 3. In Fig. 24, the same step numbers are assigned to steps common to Fig. 21 and Fig. 23, and common descriptions will be omitted.

[0371] In Step ST4501, the gNB broadcasts an SLRB configuration for relay, and mapping information between QoS-related information and the SLRB configuration. The timing of the broadcast is not limited to this. For example, the gNB may start broadcasting when it is set up. Alternatively, the gNB may start broadcasting when it supports communication using PC5. As another method, the gNB may start broadcasting after receiving the QoS-related information in Step ST4201. The gNB may broadcast the SLRB configuration corresponding to the received QoS-related information. For this reason, the gNB may broadcast multiple sets of the SLRB configuration and mapping information between the QoS-related information and the SLRB configuration. This is effective, for example, when there are multiple relay UEs served by the gNB.

[0372] In Step ST4501, the relay UE receives an SLRB configuration and mapping information between QoS-related information and the SLRB configuration, which are broadcast from the gNB. In Step ST4502, the relay UE configures an SLRB between the remote UE and the relay UE, using the QoS-related information received from the remote UE, the SLRB configuration, and mapping information between QoS-related information and the SLRB configuration received from the gNB. In Step ST4503, the relay UE notifies the remote UE of the SLRB configuration. The relay UE may notify the remote UE of the SLRB configuration in association with service-related information. The information may be information indicating which service the SLRB configuration is for, for example, information indicating which QoS flow the SLRB configuration is for. The remote UE configures an SLRB for mapping service data between the remote UE and the relay UE, using the received SLRB configuration.

[0373] In Step ST4504, the remote UE notifies the relay UE of an SLRB configuration for a service for communication between the remote UE and the relay UE. The remote UE may notify the SLRB configuration in association with service-related information. The information may be information indicating which service the SLRB configuration is for, for example, information indicating which QoS flow the SLRB configuration is for. The relay UE uses the received SLRB configuration to configure an SLRB for mapping service data between the relay UE and the remote UE.

[0374] This allows the relay UE to set up an SLRB for communicating service data in communication between the remote UE and the relay UE on the PC 5. In communication between the remote UE and the NW via the relay UE, communication according to the QoS required for the service becomes possible.

[0375] Embodiment 4 Many types of services are expected to use SL communication between UEs. For example, a service in which an RSU (Road Side Unit) on a traffic light detects a vehicle approaching at high speed and notifies pedestrians of emergency danger information data, or a service in which a pedestrian at an intersection detects a vehicle approaching at high speed and notifies the vehicle of emergency danger information data directly from the pedestrian. Such services require low latency. Therefore, low latency is a challenge in data communication for services using SL communication between UEs.

[0376] In the fourth embodiment, a method for solving such a problem will be disclosed.

[0377] Service data (sometimes referred to as user data, or simply as data) is transmitted and received in a CP (Control Plane) in PC5. For example, data may be transmitted and received by being included in signaling in a process for establishing direct communication between UEs using PC5. For example, data may be transmitted and received by being included in signaling in a direct communication process (see Non-Patent Document 26 (TS23.287)) for starting direct communication between UEs using PC5. For example, data may be transmitted and received by being included in signaling in a process for establishing a PC5-S link (sometimes referred to as a PC5 Layer 2 link or a PC5 link). Data may be transmitted and received by being included in PC5-S signaling.

[0378] Conventionally, when communicating data between UEs, the UP (User Plane) of PC5 is used, which requires processing such as UP bearer setup. By transmitting and receiving data using the CP in PC5, processing such as UP bearer setup becomes unnecessary, and it becomes possible to reduce the time required for data communication.

[0379] Fig. 25 is a sequence diagram showing a first example of a method for transmitting and receiving data at a CP in PC5 according to the fourth embodiment. Fig. 25 shows an example in which a V2X service occurs in UE-TX and service data is transmitted from UE-TX to UE-RX. Fig. 25 shows an example in which data is transmitted by being included in PC5-S signaling.

[0380] In Step ST5101, service data using SL communication is generated in the UE-TX. In Step ST5102, discovery processing (see Non-Patent Document 26 (TS23.287)) for detecting a data transmission destination is performed between the UE-TX and UE-RX. In Step ST5103, processing for establishing a PC5-S link is performed between the UE-TX and UE-RX. In Step ST5104, the UE-TX includes the data in PC5-S signaling. The UE-TX may also include the data in a PC5-S signaling message. In Step ST5105, the UE-TX transmits PC5-S signaling including the data to the UE-RX. The UE-TX may also transmit a PC5-S signaling message including the data to the UE-RX.

[0381] By receiving the PC5-S signaling, the UE-RX becomes able to receive service data from the UE-TX.

[0382] After completing the transmission of service data to UE-RX, UE-TX may perform processing to disconnect the PC5-S link between UE-RX in Step ST5106. In this way, UE-TX can transmit data before setting up an SL radio bearer (SLRB) for data transmission with UE-RX. This allows the process from the generation of service data to the completion of transmission and reception to be completed quickly.

[0383] Other examples are disclosed. For example, data may be transmitted and received by being included in PC5 RRC signaling. For example, data may be transmitted and received by being included in RRC signaling for notifying AS configuration. For example, data may be transmitted and received by being included in RRC signaling for notifying SLRB configuration.

[0384] Fig. 26 is a sequence diagram showing a second example of a method for transmitting and receiving data using a CP in PC5 according to embodiment 4. Fig. 26 shows an example in which data is transmitted by being included in PC5 RRC signaling. In Fig. 26, steps common to Fig. 25 are assigned the same step numbers, and common explanations will be omitted.

[0385] In Step ST5101, service data using SL communication is generated in the UE-TX. In Steps ST5102 to ST5103, a PC5-S link is established between the UE-TX and the UE-RX. In Step ST5201, the UE-TX includes the data in PC5 RRC signaling. The UE-TX may include the data in a message for PC5 RRC signaling. In Step ST5202, the UE-TX transmits PC5 RRC signaling including the data to the UE-RX. The UE-TX may transmit a message for PC5 RRC signaling including the data to the UE-RX.

[0386] By receiving the PC5 RRC signaling, the UE-RX becomes able to receive service data from the UE-TX.

[0387] After completing the transmission of service data to UE-RX, UE-TX may perform processing to disconnect the PC5-S link between UE-RX in Step ST5106. In this way, UE-TX can transmit data before setting up an SLRB for data transmission between UE-RX and UE-TX. This allows the process from the generation of service data to the completion of transmission and reception to be completed quickly.

[0388] Fig. 27 is a sequence diagram showing a third example of a method for transmitting and receiving data by a CP in PC5 according to embodiment 4. Fig. 27 shows an example in which data is transmitted and received by being included in PC5 RRC signaling for setting up an SLRB for data transmission and reception. In Fig. 27, steps common to Fig. 26 are assigned the same step numbers, and common explanations will be omitted.

[0389] In Step ST5101, service data using SL communication is generated in the UE-TX. In Steps ST5102 to ST5103, a PC5-S link is established between the UE-TX and the UE-RX. In Step ST5201, the UE-TX includes the data in PC5 RRC signaling. In Step ST5301, the UE-TX sets up an SLRB for data transmission. In Step ST5302, the UE-TX transmits the SLRB setting and data to the UE-RX by including them in PC5 RRC signaling.

[0390] The UE-RX becomes able to receive service data from the UE-TX by receiving PC5 RRC signaling including SLRB configuration and data.

[0391] By receiving PC5 RRC signaling including the SLRB configuration and data, the UE-RX becomes able to receive an SRLB configuration for data transmission from the UE-TX. In Step ST5303, the UE-RX transmits an SLRB configuration response to the UE-TX. The SLRB configuration response may be a notification that the SLRB configuration has been received, or may be a notification that the SLRB configuration has been completed. The SLRB configuration response may be transmitted using PC5 RRC signaling. In this way, the UE-TX can recognize that an SLRB configuration for data transmission and reception has been performed with the UE-RX.

[0392] In Step ST5304, the UE-TX, which has recognized that the data SLRB setup between the UE-TX and the UE-RX has been completed, maps the data to the SLRB. In Step ST5305, the UE-TX transmits the data mapped to the data SLRB to the UE-RX. In this way, the UE-TX may switch the data transmission to the UE-RX from CP to UP.

[0393] In this way, UE-TX can transmit data before setting up an SLRB for data transmission between UE-RX. This allows the process from service data generation to completion of transmission and reception to be completed quickly. Furthermore, after setting up an SLRB for data transmission between UE-RX and UE-TX, UE-TX can transmit data using the SLRB for data transmission, thereby satisfying the QoS required for the service.

[0394] When UE-TX switches data transmission to UE-RX from CP to UP, data currently being transmitted via CP should be transmitted and received via CP. UE-TX should transmit data via UP from the data following the data transmitted via CP. This enables efficient communication.

[0395] As another method, when UE-TX switches data transmission to UE-RX from CP to UP, data that was being transmitted in CP can be retransmitted in UP. UE-RX may receive the same data in both CP and UP, and if data is received in this manner, UE-RX should discard one of the data. For example, it should discard the data that was received last. This allows for highly reliable communication.

[0396] As another example of a method for transmitting and receiving service data in the CP in PC5, the data may be included in signaling after completion of security establishment processing in direct communication between UEs, and transmitted and received. This makes it possible to ensure confidentiality of communication. As another example, the data may be included in signaling in discovery processing, and transmitted and received. As another example, the data may be included in signaling in relay request processing when indirect communication between UEs via a relay UE or communication between a UE and a NW is performed, and transmitted and received. This makes it possible to further shorten the time until data communication.

[0397] Conventionally, service data is transmitted in PC5 via UP. Therefore, unlike conventional methods, a method for transmitting service data via CP is required in PC5. Here, a method for transmitting service data via CP is disclosed. A method for determining whether to transmit service data via CP in PC5 is also disclosed. This determination is made by the UE from which the service data is generated, i.e., UE-TX. Eleven specific examples of this determination method are disclosed below.

[0398] (1) Whether data transmission is permitted through the CP is determined based on whether security establishment processing is being performed for direct communication between UEs. For example, if security establishment processing is not being performed, data transmission through the CP is permitted. If security establishment processing is being performed, data transmission through the CP is prohibited. This makes it possible to ensure the confidentiality of communication when transmitting data through the CP.

[0399] (2) Whether or not data can be transmitted through the CP is determined based on whether or not a QoS flow for transmitting service data is set. For example, if a QoS flow is not set, data transmission through the CP is permitted. If a QoS flow is set, data transmission through the CP is prohibited. Data can be transmitted early before a QoS flow for transmitting data is set.

[0400] (3) Whether data transmission via the CP is possible is determined depending on whether an AS is configured between the UEs. Whether an AS is configured between the UEs may be determined, for example, depending on whether UE-TX has sent an AS configuration to UE-RX, or whether UE-TX has received an AS response from UE-RX. For example, if an AS is not configured, data transmission via the CP is possible. If an AS is configured, data transmission via the CP is not possible. Data can be transmitted early before a QoS flow for transmitting data is configured.

[0401] (4) Whether or not data transmission is possible through the CP may be determined based on whether an SLRB for mapping a QoS flow for transmitting service data is set. The SLRB for data transmission may be a DRB or a default bearer for data. For example, if the SLRB is not set, data transmission through the CP is possible. If the SLRB is set, data transmission through the CP is not possible. Data can be transmitted early before an SLRB for transmitting data is set.

[0402] (5) Whether data transmission through the CP is possible may be determined based on whether an SLRB for transmitting service data between UEs is set up. Whether an SLRB for transmitting service data between UEs is set up may be determined, for example, based on whether UE-TX has transmitted the SLRB setting to UE-RX, or based on whether UE-TX has received the SLRB setting response from UE-RX. For example, if the SLRB is not set up, data transmission through the CP is possible. If the SLRB is set up, data transmission through the CP is not possible. Data can be transmitted early before an SLRB for transmitting data is set up.

[0403] (6) The UE-TX in RRC_Connected state may determine whether data transmission is possible through the CP based on whether it has received an SLRB configuration from the gNB. For example, if an SLRB configuration is not received from the gNB, data transmission through the CP is possible. If an SLRB configuration is received from the gNB, data transmission through the CP is not possible. Data can be transmitted early before an SLRB is received from the gNB.

[0404] (7) The UE-TX in RRC_Idle or RRC_Inactive may determine whether data transmission is possible through the CP based on whether it has received an SLRB configuration from the gNB. For example, if an SLRB configuration is not received from the gNB, data transmission through the CP is possible. If an SLRB configuration is received from the gNB, data transmission through the CP is not possible. Data can be transmitted early before an SLRB is received from the gNB.

[0405] (8) The amount of service data to be transmitted may be used to determine whether data transmission is possible through the CP. For example, if the amount of service data to be transmitted is smaller than a predetermined amount, data transmission through the CP is permitted. If the amount of service data to be transmitted is larger than the predetermined amount, data transmission through the CP is prohibited. For example, it is possible to avoid signaling delays that may occur when a large amount of data is transmitted by including it in CP signaling. The predetermined amount may be provided to the UE-TX in advance. For example, the CN-side node may provide the predetermined amount to the UE-TX. The predetermined amount may be provided in the PC5 policy provision process. Alternatively, the predetermined amount may be set in the UE-TX in advance. The predetermined amount may differ depending on the service. The amount of data that can be transmitted through the CP can be set for each service. For example, flexible setting is possible when the amount of data to be transmitted differs depending on the service.

[0406] (9) The amount of signaling to be transmitted may be used to determine whether data transmission is possible through the CP. For example, if the sum of the amount of signaling to be transmitted and the amount of service data is smaller than a predetermined amount, data transmission through the CP is permitted. If the sum of the amount of signaling to be transmitted and the amount of service data is greater than a predetermined amount, data transmission through the CP is prohibited. For example, when the amount of signaling is large, it is possible to prevent a decrease in the coding rate due to an increase in the amount of transmitted data caused by adding service data. This makes it possible to maintain the reliability of signaling. The method disclosed in (8) may be applied as appropriate to the predetermined amount. Similar effects can be obtained.

[0407] (10) The QoS required for the service to be transmitted may be used to determine whether data can be transmitted through the CP. Some or all of the QoS parameters or characters, or 5QI may be used to determine whether data can be transmitted through the CP. For example, one of the QoS characters required for a service is a packet delay budget, which indicates the amount of delay required for the service. If the packet delay budget required for the service is smaller than a predetermined amount, data transmission through the CP is permitted. If the packet delay budget required for the service is larger than a predetermined amount, data transmission through the CP is not permitted. For example, data transmission through the CP is permitted when the amount of delay required for the service is small.

[0408] For example, if the 5QI required for the service is a predetermined 5QI, data transmission is permitted via the CP. If the 5QI required for the service is not a predetermined 5QI, data transmission is not permitted via the CP. For example, data transmission via the CP is permitted depending on the 5QI required for the service.

[0409] The predetermined amount or the predetermined QI may be provided to the UE-TX in advance, and the above-mentioned method may be applied. For example, flexible setting according to different QoS depending on the service is possible.

[0410] (11) A combination of (1) to (10).

[0411] In this way, the UE-TX can determine whether or not to transmit service data via the CP in the PC 5. It becomes possible for the PC 5 to transmit service data via the CP.

[0412] There may be provided information relating to transmission settings at the CP in the PC 5. The information relating to transmission settings at the CP in the PC 5 may be information on whether transmission at the CP in the PC 5 is permitted or not permitted.

[0413] The CN side node may notify the UE-TX of information related to transmission settings at the CP in PC5. The CN side node may notify the UE-TX of this information in a PC5 QoS policy provision process. Information related to transmission settings at the CP in PC5 may be included in the PC5 QoS policy. By doing so, for example, the CN side node can set permission or prohibition of transmission at the CP in PC5 for the UE-TX.

[0414] The CN side node may be, for example, an AMF. The AMF may perform transmission configuration at the CP in the PC5. For example, the AMF may perform transmission configuration at the CP in the PC5 using information about the UE-TX provided by the PCF. The CN side node may be, for example, an AF (Application Function). For example, a service provider may set whether transmission is permitted or not at the CP in the PC5 via the AF.

[0415] The UE-TX may notify the CN-side node of a request for setting data transmission at the CP in PC5. The UE-TX may notify the request in a PC5 QoS policy provision request process to the CN-side node. In this way, the UE-TX can request that service data generated by the UE-TX be transmitted by the CP. For example, the UE-TX can request data transmission setting at the CP depending on the radio wave propagation status between the UEs and the usage status of radio resources.

[0416] The gNB may notify the UE-TX of information regarding the transmission setting at the CP in PC5. The gNB may notify the UE-TX of information regarding the transmission setting at the CP in PC5 in the RRC connection establishment process between the UE-TX and the gNB. In this way, for example, the gNB can set permission or non-permission of transmission at the CP in PC5 to the UE-TX.

[0417] The UE-TX may notify the gNB of a request for setting up data transmission at the CP in PC5. The UE-TX may notify the request during the RRC connection establishment process between the UE-TX and the gNB. In this way, the UE-TX can request that service data generated by the UE-TX be transmitted at the CP. For example, the UE-TX can request setting up data transmission at the CP depending on the radio wave propagation conditions between the UEs and the usage conditions of radio resources.

[0418] Information regarding transmission settings at the CP in PC5 may be set in advance in the UE-TX. When the UE-TX is outside the coverage of the gNB, the information set in advance in the UE-TX may be used. Even when the UE-TX is outside the coverage of the gNB and cannot connect to the NW, transmission settings at the CP in PC5 are possible.

[0419] The above-mentioned method for determining whether transmission is possible at the CP in PC5 in the UE-TX may be combined with information on transmission settings at the CP in PC5 provided to the UE-TX. For example, if transmission is not permitted at the CP in PC5, transmission at the CP in PC5 is prohibited. If transmission is permitted at the CP in PC5, transmission at the CP in PC5 is permitted, and the method for determining whether service data is to be transmitted at the CP in PC5 is applied to determine whether transmission is possible. In this way, transmission settings at the CP, including the NW, are possible.

[0420] An SLRB may be provided for data transmission by the CP in the PC5. The SLRB may be an SRB. Alternatively, the SLRB may be set as a default setting. It is preferable that data transmission by the CP in the PC5 is performed using the SLRB.

[0421] An existing SLRB may be used as the SLRB for data transmission at the CP in PC5. The existing SLRB may be an SRB. Also, a default setting may be used for the existing SLRB. Data transmission at the CP in PC5 may be performed using the existing SLRB. This eliminates the need to set up a new SLRB for data transmission at the CP in PC5. It also becomes possible to transmit data to be transmitted at the CP together with other CP information using the same SLRB. This makes it possible to facilitate the data transmission process at the CP in PC5.

[0422] A data flow is required for transmitting service data generated in UE-TX through CP. Here, the data flow for transmitting service data through CP is disclosed.

[0423] The service data is transferred to the protocol that processes PC5 signaling (PC5 signaling protocol). For example, the service data output from the V2X layer is transferred to the PC5 signaling protocol. In the PC5 signaling protocol, the service data is included in a PC5-S message. In this way, it becomes possible to transmit the service data using PC5-S signaling.

[0424] FIG. 28 is a diagram showing a first example of a data flow in UE-TX when transmitting data via a CP according to the fourth embodiment. Data is input to a V2X layer. The layer to which data is input does not have to be a V2X layer. The layer to which data is input only needs to have a function of setting a PC5 QoS flow based on the QoS required for the service and mapping data to the set PC5 QoS flow.

[0425] In conventional data transmission in UP, data is mapped to a PC5 QoS flow set in the V2X layer and output. The data mapped to the PC5 QoS flow is input to the SDAP, where it is mapped to a data transmission SLRB set corresponding to the PC5 QoS flow. The data mapped to the data transmission SLRB is processed using the PDCP, RLC, MAC, and PHY protocols and transmitted over SL.

[0426] When transmitting data at the CP, the data is mapped to a PC5 QoS flow configured in the V2X layer. The UE-TX may configure a PC5 QoS flow and map the data, as in the case of the UP. Alternatively, the UE-TX may configure a PC5 QoS flow for data transmission at the CP and map the data. An identifier may be set in the configured PC5 QoS flow. Data of the PC5 QoS flow for data transmission at the CP is input to the PC5 signaling protocol.

[0427] Alternatively, the UE-TX may input data to be transmitted via the CP into the PC5 signaling without setting up a QoS flow.

[0428] The UE-TX outputs the service data input to the PC5 signaling protocol by including it in a PC5-S message. The UE-TX inputs the PC5-S message including the service data to the RRC. The RRC treats the PC5-S message including the service data as an RRC message. The service data may be included in the RRC message as container information or capsule information. The UE-RX does not need to decode the container information or capsule information in the RRC.

[0429] An RRC message including service data output from the RRC is mapped to an SLRB for CP, for example, an SRB, processed by the PDCP, RLC, MAC, and PHY protocols, and transmitted in the SL.

[0430] The UE-TX may input a PC5-S message including service data to PDCP without going through RRC. The UE-TX may process the PC5-S message including service data using the PDCP, RLC, MAC, and PHY protocols and transmit it in SL. For example, the UE-TX may map the PC5-S message including service data to an SRB without going through RRC, process it using the PDCP, RLC, MAC, and PHY protocols, and transmit it in SL.

[0431] By using such a data flow, it becomes possible to transmit service data generated in the UE-TX via the CP.

[0432] Another example of a data flow for transmitting service data over a CP is disclosed.

[0433] Service data is transferred to the RRC of PC5. For example, service data output from the V2X layer is transferred to the RRC. The RRC includes the service data in an RRC message. In this way, it becomes possible to transmit service data by RRC signaling.

[0434] Fig. 29 is a diagram showing a second example of a data flow in UE-TX when transmitting data via a CP according to the fourth embodiment. Mainly, differences from the disclosure in Fig. 28 will be described. Data is input to the V2X layer. When transmitting data via a CP, the data is mapped to a PC5 QoS flow set in the V2X layer. Data of the PC5 QoS flow for data transmission via the CP is input to RRC.

[0435] Alternatively, the UE-TX may input data to be transmitted via the CP to the RRC without setting up a QoS flow.

[0436] The UE-TX outputs the service data input to the RRC by including it in an RRC message. The UE-TX maps the RRC message including the service data to an SLRB for the CP, for example, an SRB. The RRC message mapped to the SLRB for the CP is processed by the PDCP, RLC, MAC, and PHY protocols and transmitted over the SL.

[0437] By using such a data flow, it becomes possible to transmit service data generated in the UE-TX via the CP.

[0438] Another example of a data flow for transmitting service data over a CP is disclosed.

[0439] An adapter may be provided that has the function of routing service data for transmission via UP and transmission via CP. The method for determining whether to transmit via CP described above may be applied to determining whether to route service data for transmission via UP or CP in the adapter.

[0440] Fig. 30 is a diagram showing a third example of a data flow in UE-TX when transmitting data via CP according to the fourth embodiment. Mainly, differences from the disclosures in Fig. 28 and Fig. 29 will be described. Data is input to an adapter. The adapter determines whether data transmission is to be performed via UP or CP. When data transmission is to be performed via UP, the data is input to the V2X layer and transmitted via SL by the method described above.

[0441] When transmitting data via CP, data output from the adapter is input to the RRC of PC5. UE-TX may input data to be transmitted via CP to RRC without setting a QoS flow. UE-TX may set a QoS flow, map data to be transmitted via CP to the QoS flow, and input the data to RRC. As described above, a PC5 QoS flow for data transmission via CP may be set and mapped.

[0442] In RRC, service data is included in an RRC message, which makes it possible to transmit service data via RRC signaling.

[0443] The UE-TX outputs the service data input to the RRC by including it in an RRC message. The UE-TX maps the RRC message including the service data to an SLRB for the CP, for example, an SRB. The RRC message mapped to the SLRB for the CP is processed by the PDCP, RLC, MAC, and PHY protocols and transmitted over the SL.

[0444] By using such a data flow, it becomes possible to transmit service data generated in the UE-TX via the CP.

[0445] Alternatively, when data is transmitted via a CP, data output from the adapter may be input to the PC5 signaling protocol. The UE-TX may input data to be transmitted via a CP to the PC5 signaling protocol without setting a QoS flow. The UE-TX may set a QoS flow, map data to be transmitted via a CP to the QoS flow, and input the data to be transmitted via a CP to the QoS flow. As described above, the UE-TX may set and map a PC5 QoS flow for data transmission via a CP.

[0446] The UE-TX outputs the service data input to the PC5 signaling protocol by including it in a PC5-S message. The method of transmitting the data input to the PC5 signaling protocol may be suitably applied to the method disclosed in FIG.

[0447] This data flow allows service data generated in UE-TX to be transmitted by CP. In addition, data transmission is possible using PC5-S signaling, which avoids the complexity of RRC signaling.

[0448] As the reception data flow in UE-RX, the transmission data flow in UE-TX described above may be modified and applied appropriately to the reception direction. The data flow may be applied to the reception direction using each protocol, layer, or function in UE-TX described above. Service data received by UE-RX via SL communication is processed by the PHY, MAC, RLC, and PDCP protocols of the SLRB configured for the CP. For example, in the example of Figure 28, data at the CP output from PDCP is mapped to the configured QoS flow, input to the V2X layer, and output as service data.

[0449] In this way, the UE-RX can receive service data received from the UE-TX at the CP. Service data can be transmitted and received between the UE-TX and the UE-RX at the CP.

[0450] Both the UP data flow and the CP data flow may be performed simultaneously. For example, service data with a large amount of data is transmitted and received using the UP data flow. Service data with a small amount of data is transmitted and received using the CP data flow. These data transmissions may be performed simultaneously. It is recommended that UE-TX and UE-RX be able to simultaneously transmit and receive both the UP data flow and the CP data flow.

[0451] Information indicating whether the UE can transmit data via the CP in PC5, information indicating whether the UE can receive data via the CP, or information indicating whether the UE can transmit and receive data via the CP may be provided. Information indicating whether data transmission and reception via the UP in PC5 and data transmission and reception via the CP in PC5 are both possible may also be provided. A UE may notify such information to a UE performing SL communication via PC5. This information may be included in UE capabilities. UEs may notify each other of UE capabilities including this information. A UE performing SL communication can recognize whether the opposing UE can perform data communication via the CP, and whether communication is possible via both the CP and the UP simultaneously.

[0452] This section discloses a channel for transmitting service data generated in UE-TX via CP.

[0453] A control channel for data transmission may be provided in the CP in PC5. For example, an SLCCH (SL Control CHannel) may be provided. The control channel may be provided as a dedicated channel. The control channel may be provided as a logical channel of PC5. When transmitting data in the CP, data may be mapped to the control channel. For example, the UE-TX may transmit data in the SL by mapping the data to be transmitted in the CP to the SLCCH, mapping the SLCCH to the SL-SCH, and mapping the SL-SCH to the PSSCH. The UE-RX receives the SL-SCH from the received PSSCH, receives the SLCCH from the SL-SCH, and receives the service data mapped to the SLCCH. This makes it possible to reduce malfunctions in data transmission and reception processing in the CP.

[0454] The UE-TX may set up data communication at the CP in PC5 for the UE-RX. The UE-TX may notify the UE-RX of the setting up of data communication at the CP in PC5. Information relating to the setting up of data communication at the CP in PC5 (sometimes referred to as CP data communication related information) may be provided. The UE-TX may notify the UE-RX of the CP data communication related information.

[0455] Seven specific examples of CP data communication related information are disclosed below.

[0456] (1) Information on whether to set up data communication via CP in PC5.

[0457] (2) Information indicating the method of data flow as described above.

[0458] (3) Information indicating the method of determining data communication at the CP mentioned above.

[0459] (4) Setting up SLRB for data communication at CP in PC5.

[0460] (5) QoS flow information for data communication at the CP in PC5.

[0461] (6) QoS flow identifier for data communication at the CP in PC5.

[0462] (7) A combination of (1) to (6).

[0463] In this way, UE-RX can recognize whether data communication is set between UE-TX and UE-RX via the CP in PC5, what the setting is, etc. Data communication via the CP in PC5 becomes possible between UE-TX and UE-RX.

[0464] The UE-TX may notify the UE-RX of the CP data communication related information in the PC5-S link establishment process. For example, the UE-TX may notify the CP data communication related information using a direct communication request message. The UE-RX may notify the UE-TX that it has received the CP data communication related information. Alternatively, the UE-RX may notify the UE-TX that it has completed the setup of the CP data communication. The UE-RX may notify the UE-TX of the completion of the setup of the CP data communication in the PC5-S link establishment process. For example, the UE-RX may notify the UE-TX of the completion of the setup of the CP data communication using a direct communication response message.

[0465] This allows the settings to be made when PC5 communication is performed, and data communication settings at the CP can be easily made during PC5 communication.

[0466] These notifications may be made during the discovery process between UE-TX and UE-RX. For example, Mode B may be used for the notifications. The notifications may be sent in solicitation messages. This allows for earlier configuration.

[0467] These notifications may be transmitted by PC5 RRC signaling between UE-TX and UE-RX. For example, the notifications may be transmitted by being included in the AS configuration used for PC5 communication. For example, the notifications may be transmitted by being included in the SLRB configuration used for PC5 communication. In this way, the amount of signaling can be reduced.

[0468] These notifications may be made before data communication is performed between UE-TX and UE-RX at the CP in PC5. UE-RX can recognize whether or not data communication is set between UE-TX and UE-RX at the CP in PC5, and what settings are made. UE-TX can recognize whether or not data communication settings at the CP in PC5 have been made in UE-RX. Data communication at the CP in PC5 becomes possible between UE-TX and UE-RX.

[0469] A field indicating that data at the CP in PC5 is included may be provided in the MAC header. A MAC control element (sometimes referred to as MAC CE) indicating that data at the CP in PC5 is included may be provided. A value indicating that data at the CP is included may be set in the MAC header or MAC CE. An LCID indicating that data at the CP in PC5 is included may be provided. An LCID for data transmission at the CP in PC5 may be provided. When transmitting data at the CP in PC5, the UE-TX sets the LCID in the MAC header. For example, the LCID may be set in the SLCCH.

[0470] In this way, the UE-RX can recognize whether or not the MAC contains data at the CP in the PC5. For example, the UE-RX can recognize whether the received data is control information or service data.

[0471] The RLC header may be provided with a field indicating that data at the CP in PC5 is included. A value indicating that data at the CP is included may be set in the RLC header. When transmitting data at the CP in PC5, the UE-TX sets a value indicating that data at the CP is included in the RLC header.

[0472] The Data / Control (D / C) field of the RLC header may be extended. For example, the field may be extended from 1 bit to 2 bits. A value indicating that data at the CP is included may be set in the field. When data transmission is performed at the CP in PC5, the UE-TX sets a value indicating that data at the CP is included in the field.

[0473] In this way, the UE-RX can recognize whether or not the RLC contains data at the CP in PC5. For example, the UE-RX can recognize whether the received data is control information or service data.

[0474] An RLC channel including data at the CP in PC5 may be provided. When data transmission is performed at the CP in PC5, UE-TX transmits the data at the CP using the RLC channel. By receiving the RLC channel, UE-RX can recognize whether data at the CP in PC5 is being transmitted. For example, UE-RX can recognize whether the received data is control information or service data.

[0475] The PDCP header may be provided with a field indicating that data at the CP in PC5 is included. A value indicating that data at the CP is included may be set in the PDCP header. When transmitting data at the CP in PC5, the UE-TX sets a value indicating that data at the CP is included in the PDCP header.

[0476] The Data / Control (D / C) field of the PDCP header may be extended. For example, the field may be extended from 1 bit to 2 bits. A value indicating that data in the CP is included may be set in the field. When data transmission is performed in the CP in PC5, the UE-TX sets a value indicating that data in the CP is included in the field.

[0477] In this way, the UE-RX can recognize whether the PDCP contains data at the CP in the PC5. For example, the UE-RX can recognize whether the received data is control information or service data.

[0478] By using the method disclosed in the fourth embodiment, it becomes possible to transmit and receive data via the CP in the PC 5. Therefore, it is no longer necessary to perform processes such as setting up a bearer for the UP of the PC 5 when communicating data between UEs as in the past. As a result, it is possible to achieve low latency in data communication for services using SL communication between UEs.

[0479] Variation 1 of Embodiment 4 In SL communication, in addition to direct communication between UEs, indirect communication via a relay has been proposed (see Non-Patent Document 29 (3GPP TR 23.703 V12.0.0)). A relay between UEs may be referred to as a UE-to-UE relay or an inter-UE relay. In the present disclosure, a UE that performs inter-UE relay may be referred to as a relay UE.

[0480] For example, when multiple UEs traveling in a convoy approach an intersection, direct communication between the UEs may become impossible due to blocking by a building or other factors. Furthermore, a UE may need to communicate not only with nearby UEs but also with multiple UEs that are farther away. In such cases, a method using a UE-to-UE relay may be considered. For example, SL communication between a transmitting UE (sometimes referred to as UE-TX) and a receiving UE (sometimes referred to as UE-RX) may be performed via a relay UE. SL communication between UEs via a relay UE may be referred to as indirect communication between UEs.

[0481] In the indirect communication between UEs via the relay UE, the communication of service data may be performed at the CP in the PC 5.

[0482] In the indirect communication between UEs via the relay UE, service data may be communicated between the UE-TX and the relay UE at the CP in the PC5, or service data may be communicated between the relay UE and the UE-RX at the CP in the PC5. Alternatively, both of these may be performed. The method disclosed in the fourth embodiment may be applied as appropriate to these service data communications at the CP in the PC5.

[0483] In the case of indirect communication between UEs via a relay UE, unlike direct communication between UEs, data is forwarded by the relay UE. The relay UE may determine whether to transmit data received from UE-TX to UE-RX via CP or UP. The method of determining whether to transmit service data via CP in PC5, as disclosed in the fourth embodiment, may be applied as appropriate to this determination method.

[0484] For example, whether data transmission through the CP is possible may be determined based on whether an SLRB for transmitting service data is set between the relay UE and UE-RX. Whether an SLRB for transmitting service data is set between the relay UE and UE-RX may be determined based on whether the relay UE has transmitted the SLRB setting to the UE-RX, or whether the relay UE has received the SLRB setting response from the UE-RX. For example, if the SLRB is not set, data transmission through the CP is possible. If the SLRB is set, data transmission through the CP is not possible. Data can be transmitted early before an SLRB for transmitting data is set.

[0485] In this way, it becomes possible to determine whether data transmission is possible at the CP depending on the situation between the relay UE and UE-RX.

[0486] Another method is disclosed. UE-TX may determine whether to transmit data received from UE-TX via CP or UP between relay UE and UE-RX. Information indicating whether to transmit via CP or UP may be provided. Information indicating whether to transmit via CP or UP may be provided between relay UE and UE-RX. UE-TX notifies the relay UE of this information. The relay UE determines whether to transmit data between UE-RX and UE-RX via CP or UP according to this information.

[0487] If the information received from UE-TX indicates that data should be transmitted via UP, the relay UE transmits the data to UE-RX via UP. If the information received from UE-TX indicates that data should be transmitted via CP, the relay UE transmits the data to UE-RX via CP.

[0488] The information may be notified by PC5-S signaling. This allows the information to be notified at an early stage. Alternatively, the information may be notified by PC5 RRC signaling. For example, the UE-TX may notify the relay UE of the SLRB configuration between the relay UE and UE-RX. In this case, the SLRB configuration may include information indicating whether data is to be transmitted via CP or UP. This makes it possible to reduce the amount of signaling.

[0489] Information indicating whether to transmit using CP or UP may be provided in the header of SDAP, PDCP, RLC, or MAC. UE-TX sets information indicating whether to transmit using CP or UP in the header of SDAP, PDCP, RLC, or MAC, and transmits the information to the relay UE. The relay UE determines whether to transmit data using CP or UP between itself and UE-RX according to the information indicating whether to transmit using CP or UP set in the header.

[0490] In this way, the UE-TX can determine whether or not to perform data communication between the relay UE and the UE-RX via a CP. For example, the UE-TX may determine whether or not to perform data communication from the relay UE to the UE-RX via a CP, depending on the QoS required for a service generated in the UE-TX. Since the UE-TX generating service data can make this determination depending on the QoS required for the service, it becomes possible to satisfy the QoS required for the service.

[0491] Another method is disclosed. When data communication between UE-TX and relay UE is performed at the CP, data communication between relay UE and UE-RX is also performed at the CP. When relay UE receives data from UE-TX at the CP, it transmits the data to UE-RX at the CP. In this way, data communication between UE-TX and relay UE, and between relay UE and UE-RX can be performed on the same plane (CP or UP). This makes it possible to simplify relay control processing and reduce the occurrence of malfunctions.

[0492] Fig. 31 is a sequence diagram showing a first example of a method for transmitting data at a CP via a relay UE in accordance with Modification 1 of Embodiment 4. A V2X service occurs in UE-TX, and the service data is transmitted from UE-TX to UE-RX via the relay UE. Fig. 31 shows an example in which data is transmitted in PC5-S signaling between UE-TX and relay UE, and between relay UE and UE-RX.

[0493] In Step ST5701, service data using SL communication is generated in the UE-TX. In Step ST5702, the UE-TX starts a relay request process to the relay UE. In Step ST5703, a discovery process is performed between the relay UE and UE-RX to detect the data transmission destination. In Step ST5704, the relay UE that has detected the data transmission destination notifies the UE-TX of a relay response. In the relay response, the relay UE may notify the UE-TX of information indicating that relaying to the destination UE-RX is possible. The UE-TX can recognize that data communication to the UE-RX is possible via the relay UE.

[0494] In Step ST5705, a process for establishing a PC5-S link is performed between the UE-TX and the relay UE. In Step ST5706, a process for establishing a PC5-S link is performed between the relay UE and the UE-RX. The method disclosed in the fourth embodiment and the method described above may be applied as appropriate to the service data communication at the CP in these PC5s.

[0495] For example, the UE-TX determines to transmit data to the relay UE using the CP in PC5. In Step ST5707, the UE-TX includes the data in PC5-S signaling. The UE-TX may include the data in a message for PC5-S signaling. In Step ST5708, the UE-TX transmits PC5-S signaling including the data to the UE-RX. The UE-TX may transmit a message for PC5-S signaling including the data to the UE-RX.

[0496] The relay UE that has received the data from UE-TX at the CP decides to transmit data to UE-RX at the CP in PC5. In Step ST5709, the relay UE includes the data in PC5-S signaling. The relay UE may include the data in a message for PC5-S signaling. In Step ST5710, the relay UE transmits PC5-S signaling including the data to UE-RX. The relay UE may transmit a message for PC5-S signaling including the data to UE-RX.

[0497] By receiving the PC5-S signaling, the UE-RX becomes able to receive service data from the UE-TX via the relay UE.

[0498] The UE-TX, which has completed transmitting service data to the relay UE, may perform processing to disconnect the PC5-S link with the relay UE in Step ST5711. Furthermore, the relay UE, which has completed transmitting service data to the UE-RX, may perform processing to disconnect the PC5-S link with the UE-RX in Step ST5712. In this way, data transmission from the UE-TX to the UE-RX via the relay UE becomes possible before an SLRB for data transmission between the UE-TX and the relay UE and an SLRB for data transmission between the relay UE and UE-RX are set up. In indirect communication between UEs via a relay UE, the process from the generation of service data to the completion of transmission and reception can be performed quickly.

[0499] Fig. 32 is a sequence diagram showing a second example of a method for transmitting data at a CP via a relay UE in accordance with Variation 1 of Embodiment 4. A V2X service occurs in UE-TX, and the service data is transmitted from UE-TX to UE-RX via the relay UE. Fig. 32 shows an example in which data is transmitted in PC5 RRC signaling between UE-TX and relay UE, and between relay UE and UE-RX. In Fig. 32, steps common to those in Fig. 31 are assigned the same step numbers, and common explanations will be omitted.

[0500] In Step ST5701, service data using SL communication is generated in the UE-TX. In Steps ST5702 to ST5706, PC5-S links are established between the UE-TX and the relay UE and between the relay UE and UE-RX. In Step ST5801, the UE-TX includes the data in PC5 RRC signaling. The UE-TX may include the data in a message for PC5 RRC signaling. In Step ST5802, the UE-TX transmits PC5 RRC signaling including the data to the relay UE. The UE-TX may transmit a message for PC5 RRC signaling including the data to the relay UE.

[0501] The relay UE that has received the data from UE-TX via the CP decides to transmit data to UE-RX via the CP in PC5. In Step ST5803, the relay UE includes the data in PC5 RRC signaling. The relay UE may include the data in a message for PC5 RRC signaling. In Step ST5804, the relay UE transmits PC5 RRC signaling including the data to UE-RX. The relay UE may transmit a message for PC5 RRC signaling including the data to UE-RX.

[0502] By receiving the PC5 RRC signaling, the UE-RX becomes able to receive service data from the UE-TX via the relay UE.

[0503] In this way, data transmission from UE-TX to UE-RX via the relay UE becomes possible before the setting of an SLRB for data transmission between UE-TX and the relay UE, and the setting of an SLRB for data transmission between the relay UE and UE-RX. In indirect communication between UEs via the relay UE, the process from the generation of service data to the completion of transmission and reception can be carried out quickly.

[0504] In indirect communication between UEs via a relay UE, a PC5-S link may be established between UE-TX and UE-RX. In such a case, service data may be transmitted between UE-TX and UE-RX via a CP. The method disclosed in the fourth embodiment may be applied as appropriate. For example, UE-TX may determine whether to transmit service data between UE-TX and UE-RX via a CP.

[0505] For example, the UE-TX may determine whether to transmit service data between the UE-TX and the UE-RX using the CP by determining whether a bearer for transmitting data using the UP has been established between the UE-TX and the UE-RX. If a bearer for transmitting data using the UP has not been established between the UE-TX and the relay UE, between the relay UE and the UE-RX, or between the UE-TX and the UE-RX, the UE-TX may determine that a bearer for transmitting data using the UP has not been established between the UE-TX and the UE-RX. If a bearer for transmitting data using the UP has not been established between the UE-TX and the UE-RX, the UE-TX transmits data using the CP. If a bearer for transmitting data using the UP has been established between the UE-TX and the UE-RX, the UE-TX transmits data using the UP.

[0506] As a method of transmitting data in the CP, for example, the data may be transmitted by being included in PC5-S signaling from UE-TX to UE-RX.

[0507] By doing so, in indirect communication between UEs via a relay UE, even when a PC5-S link is established between UE-TX and UE-RX, service data can be transmitted via the CP. In indirect communication between UEs via a relay UE, the process from the generation of service data to the completion of transmission and reception can be carried out quickly.

[0508] Embodiment 5 3GPP is currently discussing network slicing, which involves slicing network resources and using a slice for each service (see Non-Patent Document 16 (TS38.300)). In network slicing, a different slice is used for each PDU session. For this reason, S-NSSAI (Single layer-Network Slice Selection Assistance Information), which indicates the identifier of one slice, is provided for each PDU session.

[0509] A list of supported S-NSSAI(s) is notified in advance between the RAN node and the AMF. When a PDU session is established, the AMF notifies the RAN node of the S-NSSAI to be used in the PDU session. The AMF includes the S-NSSAI information in a PDU session resource setup request message and notifies the RAN node. In this way, the AMF requests the RAN node to reserve and use resources for the slice.

[0510] In PC5 communication, one V2X service is associated with one or more QoS flows, one PC5-S link is associated with one or more V2X services, and one PC5-S link is associated with one or more QoS flows for the same or different V2X services.

[0511] In this way, in a V2X service using PC5 communication, QoS is managed based on the QoS flow. A PDU session is not established. Therefore, even if you try to perform network slicing in a V2X service using PC5 communication, a PDU session for setting S-NSSAI is not established. This makes it impossible to perform network slicing.

[0512] In the fifth embodiment, a method for solving such a problem will be disclosed.

[0513] A different slice may be used for each V2X service. One S-NSSAI may be provided for each V2X service. Alternatively, a different slice may be used for each V2X service group consisting of one or more V2X services. One S-NSSAI may be provided for each V2X service group. A different slice may be used for each PC5-S link. One S-NSSAI may be provided for each PC5-S link.

[0514] One or more slices may be used for each V2X service. One or more S-NSSAI(s) may be provided for each V2X service. For example, a different slice may be used for each PC5 QoS flow. One S-NSSAI may be provided for each PC5 QoS flow.

[0515] A QoS rule for PC5 communication may be set for each QoS flow for PC5 communication (PC5 QoS flow). A QoS parameter for PC5 communication may be set for each QoS flow for PC5 communication. A QoS flow for PC5 communication may be set for each QoS parameter for PC5 communication. For example, when multiple QoS parameters are set for a V2X service using PC5 communication, a different slice may be used for each QoS parameter. One S-NSSAI may be provided for each QoS parameter. This results in a different slice being used for each PC5 QoS flow.

[0516] By doing this, the unit for dividing resources into slices in PC5 communication is set.

[0517] The case of UE-to-UE indirect communication between UE-TX and UE-RX via a relay UE is disclosed.

[0518] Information on S-NSSAI(s) for PC5 communication is provided to UE-TX. The information on S-NSSAI(s) for PC5 communication may be, for example, S-NSSAI(s) information for PC5 communication that is supportable by UE-TX. The information may be, for example, S-NSSAI(s) information for PC5 communication or association information between S-NSSAI(s) and services. For example, a CN side node notifies UE-TX of information on S-NSSAI(s) for PC5 communication. The CN side node may be, for example, a PCF or an AMF. The CN side node may notify the UE of the information on S-NSSAI(s) for PC5 communication via a gNB.

[0519] Information regarding the S-NSSAI(s) for PC5 communication may be preset in the UE-TX. The information preset in the UE-TX may be used when the UE-TX is outside the coverage of the gNB and cannot connect to the NW. The UE-TX can acquire information regarding the S-NSSAI(s) for PC5 communication even when it is outside the coverage of the gNB.

[0520] Information about the S-NSSAI(s) for PC5 communication may be provided to the relay UE or UE-RX. The above-mentioned method may be applied. In this way, the relay UE or UE-RX can also obtain information about the S-NSSAI(s) for PC5 communication.

[0521] The UE-TX determines the service to be implemented using PC5 communication and the corresponding S-NSSAI. For this determination, the association information between the service and the S-NSSAI(s) received from the CN side node may be used. The UE-TX notifies the relay UE of the determined S-NSSAI. The UE-TX may notify the determined S-NSSAI(s) in association with the service. For this notification, for example, PC5-S signaling or RRC signaling may be used. The notification may be transmitted in the form of being included in the AS configuration.

[0522] The UE-TX determines a PC5 QoS flow for transmitting service data implemented using PC5 communication and a corresponding S-NSSAI(s). The UE-TX notifies the relay UE of the determined S-NSSAI(s). The UE-TX may notify the determined S-NSSAI(s) in association with the PC5 QoS flow. A PFI (PC5 QoS Flow Indicator) may be used to identify the PC5 QoS flow. For this notification, signaling for notifying the PFI from the UE-TX to the relay UE may be used. For example, PC5-S signaling or RRC signaling may be used for this notification. The notification may be transmitted in the form of being included in the AS configuration.

[0523] The UE-TX may associate the determined S-NSSAI(s) with the QoS-related information used to derive the PC5 QoS flow, and notify the relay UE of the association. The notification may be performed using signaling for notifying the QoS-related information from the UE-TX to the relay UE. For example, the notification may be performed using PC5-S signaling or RRC signaling. The notification may be transmitted in the form of an AS configuration.

[0524] The UE-TX determines the PC5-S link established for the service implemented using PC5 communication and the corresponding S-NSSAI(s). The UE-TX notifies the relay UE of the determined S-NSSAI(s). The UE-TX may notify the determined S-NSSAI(s) in association with the PC5-S link. An identifier for identifying the PC5-S link may be used. For example, the notification may be performed using PC5-S signaling or RRC signaling. The notification may be transmitted in the form of being included in the AS configuration.

[0525] The UE-TX determines the destination of the service to be implemented using PC5 communication and the corresponding S-NSSAI(s). The UE-TX notifies the relay UE of the determined S-NSSAI(s). The UE-TX may notify the determined S-NSSAI(s) in association with the destination. A DST L2ID (Destination Layer 2 ID) may be used to identify the destination. For this notification, signaling for notifying the PFI from the UE-TX to the relay UE may be used. For this notification, for example, PC5-S signaling or RRC signaling may be used. The notification may be transmitted in the form of being included in the AS configuration.

[0526] In this way, the relay UE becomes able to recognize the services, PC5-S links, PC5 QoS flows, etc. between the UE-TX and the relay UE, as well as the S-NSSAI(s) used therefor.

[0527] The relay UE may notify the UE-RX of the S-NSSAI(s) or information associating the S-NSSAI(s) with services. For example, the notification may be performed using PC5-S signaling or RRC signaling. The notification may be transmitted in the form of an AS configuration.

[0528] The relay UE may associate the S-NSSAI(s) with the PC5 QoS flow and notify the UE-RX. For the notification, signaling for notifying the PFI from the relay UE to the UE-RX may be used. For the notification, for example, PC5-S signaling or RRC signaling may be used. The notification may be transmitted in the form of being included in the AS configuration.

[0529] The relay UE may associate the S-NSSAI(s) with the QoS related information used to derive the PC5 QoS flow and notify the UE-RX of the S-NSSAI(s). The notification may be performed using signaling for notifying the QoS related information from the relay UE to the UE-RX. For example, the notification may be performed using PC5-S signaling or RRC signaling. The notification may be transmitted in the form of an AS configuration.

[0530] The relay UE may associate the S-NSSAI(s) with the PC5-S link and notify the UE-RX. An identifier for identifying the PC5-S link may be used. For example, the notification may be performed using PC5-S signaling or RRC signaling. The notification may be transmitted in the form of an AS configuration.

[0531] The relay UE may associate the S-NSSAI(s) with the destination and notify the UE-RX. For the notification, signaling for notifying the PFI from the UE-TX to the relay UE may be used. For the notification, for example, PC5-S signaling or RRC signaling may be used. The notification may be transmitted in the form of an AS configuration.

[0532] In this way, the UE-RX becomes able to recognize the services, PC5-S links, PC5 QoS flows, etc. between the relay UE, and also becomes able to recognize the S-NSSAI(s) used therefor.

[0533] Radio resources in a UE performing PC5 communication may be divided into slices. Examples of radio resources in a UE include a buffer capacity used by the UE and control processing capabilities in the UE. A UE performing PC5 communication may be a UE-TX, a relay UE, or a UE-RX. The relay UE can configure radio resources in the UE to be used by using information on services using PC5 communication and the corresponding S-NSSAI(s) received from the UE-TX. The UE-RX can configure radio resources in the UE to be used by using information on V2X services using PC5 communication and the corresponding S-NSSAI(s) received from the relay UE.

[0534] The configuration of radio resources in UEs performing PC5 communication using slices may be performed by a management node. For example, OAM (Operations, Administration, Maintenance) may perform the configuration. The management node may notify UEs performing PC5 communication of the radio resources to be used for slices in advance. This enables unified operation of radio resources for UEs under the management of the management node. This makes it possible to improve the utilization efficiency of radio resources in the entire system.

[0535] In this way, it becomes possible to slice radio resources in the UE in indirect communication between UEs via a relay UE.

[0536] The above-described method may also be applied to communication between a UE and a network via a relay UE, and the same effect can be obtained.

[0537] In the case of communication between a UE and a network via a relay UE, the relay UE may notify the gNB of the information notified from the relay UE to the UE-RX as described above. As a method of notification from the relay UE to the gNB, Uu signaling may be used. For example, Uu RRC signaling may be used. In this way, in communication between a UE and a network via a relay UE, the gNB can slice radio resources using S-NSSAI(s).

[0538] In the case of communication between a UE and a NW via a relay UE, the relay UE may notify the CN-side node of the information notified from the relay UE to the UE-RX as described above. Uu and N2 signaling may be used as a notification method from the relay UE to the gNB. For example, RRC signaling and N2 signaling may be used. Furthermore, for example, NAS signaling may be used. In this way, in communication between a UE and a NW via a relay UE, the CN-side node can slice radio resources using the S-NSSAI(s).

[0539] By using the method disclosed in the fifth embodiment, slicing becomes possible even in indirect communication between UEs via a relay UE and in communication between a UE and a NW via a relay UE. By using slicing in these communications, it becomes possible to satisfy the QoS required for the services to be executed.

[0540] In the present disclosure, the UE in which service data is generated is referred to as UE-TX. For example, if UE-TX is referred to as UE1 and UE-RX is referred to as UE2, when service data is generated in UE2 and the data is transmitted to UE1, it is advisable to apply the method of the present disclosure by treating UE2 as UE-TX and UE1 as UE-RX. Similar effects can be obtained.

[0541] The above-described embodiments and their modifications are merely examples, and the embodiments and their modifications can be freely combined. Furthermore, any of the components of the embodiments and their modifications can be modified or omitted as appropriate.

[0542] For example, in the above-described embodiments and their modifications, a subframe is an example of a time unit for communication in a fifth-generation base station communication system. It may also be a scheduling unit. In the above-described embodiments and their modifications, the processing described as being performed in subframe units may also be performed in TTI units, slot units, subslot units, or minislot units.

[0543] For example, the methods disclosed in the above-described embodiments and their modifications may be applied to services that use SL communication, not limited to V2X (Vehicle-to-everything) services, such as proximity-based services, public safety, communication between wearable devices, and communication between devices in factories.

[0544] It should be noted that the embodiments can be freely combined, and the embodiments can be modified or omitted as appropriate. Although the present disclosure has been described in detail, the above description is illustrative in all respects and is not limiting. It is understood that countless variations not illustrated can be envisioned. [Explanation of symbols]

[0545] 200, 210 communication system, 202 communication terminal device (communication terminal), 203, 207, 213, 217, 223-1, 224-1, 224-2, 226-1, 226-2 base station device (base station), 204, 214 management device.

Claims

1. A first communication terminal device in a communication system, The communication system includes a plurality of communication terminal devices that perform sidelink communication via a PC5 interface, and a network including one or more core network nodes; the plurality of communication terminal devices include the first communication terminal device and the second communication terminal device, the one or more core network nodes include a Session Management Function (SMF); the first communication terminal device is a relay communication terminal device that performs a relay between the second communication terminal device and the network, The first communication terminal device establishes a PDU (Protocol Data Unit) session between the first communication terminal device and the network, the PDU session being used for the relay; The first communication terminal device is configured to transmit information regarding the second communication terminal device to the SMF in a procedure for establishing the PDU session for the relay; A first communication terminal device.

2. the information about the second communication terminal device includes IP (Internet Protocol) information; 2. The first communication terminal device according to claim 1.

3. The first communication terminal device is configured to send a PDU session modification request including QoS (Quality of Service) related information to the SMF in a procedure for modifying the PDU session for the relay; 2. The first communication terminal device according to claim 1.

4. The first communication terminal device is configured to transmit second information regarding the second communication terminal device to the SMF after establishing the PDU session for the relay; the second information regarding the second communication terminal device includes identification information for identifying the second communication terminal device; 2. The first communication terminal device according to claim 1.

5. The second information regarding the second communication terminal device is stored in the SMF and associated with the PDU session for the relay.

5. The first communication terminal device according to claim 4.

6. After establishing the PDU session for the relay, a discovery process is performed between the first communication terminal device and the second communication terminal device.

2. The first communication terminal device according to claim 1.

7. the first communication terminal device is configured to receive, in the discovery processing, from the second communication terminal device, information indicating that the second communication terminal device is searching for a communication terminal device having a relay function.

7. The first communication terminal device according to claim 6.

8. the first communication terminal device is configured to transmit, in the discovery process, to the second communication terminal device, information indicating that the first communication terminal device has a relay function.

7. The first communication terminal device according to claim 6.

9. The first communication terminal device is configured to establish a PC5 connection via the PC5 interface between the first communication terminal device and the second communication terminal device after establishing the PDU session for the relay.

2. The first communication terminal device according to claim 1.

10. the procedure for establishing the PC5 connection is initiated by the second communication terminal device; the first communication terminal device is configured to receive a request for establishment of the PC5 connection from the second communication terminal device; The first communication terminal device according to claim 9.

11. the first communication terminal device is configured to receive, from the second communication terminal device, first identification information for identifying the first communication terminal device that is a destination, and second identification information for identifying the second communication terminal device that is a source, in the procedure for establishing the PC5 connection; The first communication terminal device according to claim 10.

12. the first communication terminal device is configured to further receive service-related information from the second communication terminal device during the procedure of establishing the PC5 connection; The first communication terminal device according to claim 10.

13. The first communication terminal device is configured to further receive information for requesting the relay from the second communication terminal device in the procedure for establishing the PC5 connection. The first communication terminal device according to claim 10.

14. Between the first communication terminal device and the second communication terminal device, a default SLRB (sidelink Radio Bearer) for PC5-S signaling and a default SLRB for PC5-RRC (Radio Resource Control) signaling are set, The first communication terminal device according to claim 9.

15. A second communication terminal device in a communication system, The communication system includes a plurality of communication terminal devices that perform sidelink communication via a PC5 interface, and a network including one or more core network nodes; the plurality of communication terminal devices include a first communication terminal device and the second communication terminal device; the first communication terminal device is a relay communication terminal device that performs a relay between the second communication terminal device and the network, A PDU (Protocol Data Unit) session between the first communication terminal device and the network is established, the PDU session being used for the relay; The second communication terminal device is configured to perform a discovery process between the first communication terminal device and the second communication terminal device after the PDU session for the relay is established. A second communication terminal device.

16. a plurality of communication terminal devices that perform sidelink communication via a PC5 interface, the plurality of communication terminal devices including a first communication terminal device and a second communication terminal device; a network including one or more core network nodes including a Session Management Function (SMF); A communication system comprising: the first communication terminal device is a relay communication terminal device that performs a relay between the second communication terminal device and the network, The first communication terminal device establishes a PDU (Protocol Data Unit) session between the first communication terminal device and the network, the PDU session being used for the relay; The first communication terminal device is configured to transmit information regarding the second communication terminal device to the SMF in a procedure for establishing the PDU session for the relay; Communication system.

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