First terminal device, second terminal device, and communication system

Abstract

To reduce power consumption in a communication system using terminal-to-terminal communication.SOLUTION: A communication system includes a plurality of terminal devices (202) that perform unicast communication in sidelink communication via a PC5 interface, where the plurality of terminal devices include a first terminal device (UE-TX), which is a terminal device on a transmitting side, and a second terminal device (UE-RX), which is a terminal device on a receiving side. The first terminal device determines a DRX (Discontinuous Reception) setting for the receiving operation of the second terminal device in unicast communication and transmits the DRX setting to the second terminal device.SELECTED DRAWING: Figure 32

Description

Technical Field

[0001] This disclosure relates to wireless communication technology.

Background Art

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

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

[0004] The decisions made by 3GPP regarding the frame structure in LTE systems, as described in Non-Patent Document 1 (Chapter 5), will be explained using Figure 1. Figure 1 is an explanatory diagram showing the structure of a radio frame used in an LTE communication system. In Figure 1, one radio frame is 10ms. A radio frame is divided into 10 subframes of equal size. Each subframe is divided into two slots of equal size. Downlink synchronization signals are included in the 1st and 6th subframes of each radio frame. The synchronization signals consist of a primary synchronization signal (P-SS) and a secondary synchronization signal (S-SS).

[0005] Non-patent document 1 (Chapter 5) describes the 3GPP's decisions regarding channel configuration in LTE systems. It is assumed that the same channel configuration as non-CSG cells will be used in CSG (Closed Subscriber Group) cells.

[0006] The Physical Broadcast Channel (PBCH) is a channel used for downlink transmission from base station equipment (hereinafter sometimes simply referred to as "base station") to communication terminal equipment (hereinafter sometimes simply referred to as "mobile terminal") and other such devices. A PBCH transport block is mapped to four subframes within a 40ms interval. There is no explicit signaling at 40ms timing.

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

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

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

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

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

[0012] The Physical Uplink Shared Channel (PUSCH) is a channel used 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 the channel used for downlink transmission from the base station to the communication terminal. PHICH carries the Ack / Nack, which is the response signal to uplink transmissions. The Physical Random Access Channel (PRACH) is the channel used for uplink transmission from the communication terminal to the base station. PRACH carries the random access preamble.

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

[0015] Similarly, the uplink reference signals are also known symbols for LTE communication systems. Two types of uplink reference signals are defined: the Demodulation Reference Signal (DM-RS) and the Sounding Reference Signal (SRS).

[0016] This section explains the transport channel described in Non-Patent Document 1 (Chapter 5). Of the downlink transport channels, the Broadcast Channel (BCH) broadcasts to the entire coverage of the base station (cell). The BCH is mapped to the Physical Broadcast Channel (PBCH).

[0017] Downlink Shared Channels (DL-SCH) are subject to retransmission control using HARQ (Hybrid ARQ). DL-SCH can 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) for communication terminals to reduce power consumption. DL-SCH is mapped to Physical Downlink Shared Channels (PDSCH).

[0018] Paging Channels (PCHs) support DRX for communication terminals to enable low power consumption for those terminals. PCHs are required to broadcast across the entire coverage of a base station (cell). PCHs are mapped to physical resources, such as Physical Downlink Shared Channels (PDSCHs), which are dynamically available for traffic.

[0019] Multicast channels (MCHs) are used for broadcasting across the entire coverage of a base station (cell). MCHs support SFN synthesis of MBMS (Multimedia Broadcast Multicast Service) services (MTCH and MCCH) in multi-cell transmission. MCHs support quasi-static resource allocation. MCHs are mapped to PMCHs.

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

[0021] Random Access Channels (RACHs) are limited to control information. RACHs carry a risk of collisions. RACHs are mapped to Physical Random Access Channels (PRACHs).

[0022] This section explains HARQ. HARQ is a technology that improves the communication quality of a transmission path by combining Automatic Repeat reQuest (ARQ) and Forward Error Correction. HARQ has the advantage that error correction works effectively through retransmission even on transmission paths where the communication quality changes. In particular, it is possible to achieve further quality improvement by combining the reception results of the initial transmission and the retransmission during retransmission.

[0023] Here is an example of how to retransmit data. If the receiving side is unable to correctly decode the received data, in other words, if a CRC (Cyclic Redundancy Check) error occurs (CRC=NG), the receiving side sends "Nack" to the sending side. Upon receiving "Nack," the sending side retransmits the data. If the receiving side is able to correctly decode the received data, in other words, if no CRC error occurs (CRC=OK), the receiving side sends "Ack" to the sending side. Upon receiving "Ack," the sending side sends the next data.

[0024] This section explains the logical channel described in Non-Patent Document 1 (Chapter 6). The Broadcast Control Channel (BCCH) is a downstream channel for broadcast system control information. The BCCH, being a logical channel, is mapped to the broadcast channel (BCH), which is a transport channel, or to the downstream shared channel (DL-SCH).

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

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

[0027] A Multicast Control Channel (MCCH) is a downlink channel for one-to-many transmission. MCCHs are used to transmit MBMS control information for one or more MCCHs from the network to communication terminals. MCCHs are only used by communication terminals receiving MBMS. MCCHs are mapped to the Multicast Channel (MCH), which is the transport channel.

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

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

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

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

[0032] Location tracking of communication terminals is performed in units of areas consisting of one or more cells. Location tracking is performed to track the location of communication terminals even when they are in standby mode, and to enable them to be called, in other words, to allow them to receive calls. This area used for location tracking of communication terminals is called the tracking area.

[0033] Furthermore, 3GPP is working on 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 method and incorporates several new technologies.

[0034] In LTE-A systems, carrier aggregation (CA), which involves aggregating two or more component carriers (CCs) to support wider transmission bandwidths up to 100 MHz, is being considered. CA is described in Non-Patent Document 1.

[0035] When a CA is configured, the UE has a single RRC connection to the network (NW). In the RRC connection, one serving cell provides NAS mobility information and security inputs. This cell is called the Primary Cell (PCell). On the downlink, the carrier corresponding to the PCell is the Downlink Primary Component Carrier (DL PCC). On the uplink, the carrier corresponding to the PCell is the Uplink Primary Component Carrier (UL PCC).

[0036] Depending on the capabilities of the UE, secondary cells (SCells) are configured to form a set of serving cells together with PCells. On the downlink, the carrier corresponding to the SCell is the Downlink Secondary Component Carrier (DL SCC). On the uplink, the carrier corresponding to the SCell is the Uplink Secondary Component Carrier (UL SCC).

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

[0038] Furthermore, new technologies in LTE-A include technologies that support wider bandwidths (Wider bandwidth extension) and technologies such as Coordinated Multiple Point transmission and reception (CoMP). The CoMP technology being considered by 3GPP for LTE-A is described in Non-Patent Document 1.

[0039] Furthermore, 3GPP is considering using small eNBs (sometimes referred to as "small-scale base station equipment") that constitute small cells to cope with the enormous traffic of the future. For example, technologies are being considered to increase communication capacity by improving frequency utilization efficiency by installing a large number of small eNBs to constitute a large number of small cells. Specifically, this includes dual connectivity (DC), in which a UE connects to and communicates with two eNBs. DC is described in Non-Patent Document 1.

[0040] In some cases, among eNBs that perform dual connectivity (DC), one is called the "master eNB (abbreviated as MeNB)" and the other is called the "secondary eNB (abbreviated as SeNB)".

[0041] Mobile network traffic is on the rise, and communication speeds are also increasing. Further speed increases are expected once LTE and LTE-A are fully operational.

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

[0043] In 5G wireless access systems, the requirements include achieving 1000 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 for communication terminals compared to LTE systems, while also achieving further reductions in power consumption and equipment costs.

[0044] To meet these requirements, 3GPP is working on the 5G standard as Release 15 (see Non-Patent Documents 6-19). The technology for the wireless portion of 5G 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 compared to the LTE system and LTE-A system.

[0046] For NR access, OFDM is used for the downstream direction, and OFDM and DFT-s-OFDM (DFT-spread-OFDM) are used for the upstream direction.

[0047] NR allows for the use of higher frequencies compared to LTE, in order to improve transmission speed and reduce processing delays.

[0048] In NR (Noise Reduction), 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] In NR's frame configuration, various subcarrier intervals, i.e., various numerologies, are supported. In NR, regardless of the numerology, one subframe is 1 millisecond, and one slot consists of 14 symbols. Furthermore, the number of slots contained in one subframe is one for a numerology with a subcarrier interval of 15 kHz, and increases proportionally with the subcarrier interval for other numerologies (see Non-Patent Document 13 (TS38.211)).

[0050] In NR, the downlink synchronization signal is transmitted from the base station as a synchronization signal burst (SS burst) at a predetermined period and for a predetermined duration. The SS burst consists of a synchronization signal block (SS block) for each beam of the base station. The base station transmits the SS block for each beam, changing beams within the duration of the SS burst. The SS block consists of P-SS, S-SS, and PBCH.

[0051] In noise reduction (NR), the effect of phase noise is reduced by adding a Phase Tracking Reference Signal (PTRS) as the downstream reference signal. Similarly, a PTRS is also added to the upstream reference signal.

[0052] In NR, Slot Format Indication (SFI) information has been added to the PDCCH to allow for flexible switching between DL / UL within a slot.

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

[0054] 3GPP is considering several data center configurations, including a data center with LTE and NR base stations connected to an EPC, a data center with NR base stations connected to a 5G core system, and a data center with LTE and NR base stations connected to a 5G core system (see Non-Patent Documents 12, 16, and 19).

[0055] Furthermore, 3GPP is considering supporting services (or applications) using side-link (SL) communication in both EPS and 5G core systems (see Non-Patent Documents 1, 16, 20, 21, 22, and 23). Examples of services using SL communication include V2X services and proximity services. [Prior art documents] [Non-patent literature]

[0056] [Non-Patent Document 1] 3GPP TS 36.300 V16.2.0 [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 V16.0.0 [Non-Patent Document 5] "Scenarios, requirements and KPIs for 5G mobile and wireless system", ICT-317669-METIS / D1.1

Non-licensed Document 6

Non-licensed Document 7

Non-licensed literature 9

Non-licensed literature 10

Non-licensed Document 11

Non-licensed Document 12

Non-licensed Document 13

Non-licensed Document 14

Non-licensed Document 15

Non-licensed Document 16

Non-licensed Document 17

Non-licensed Document 18

Non-licensed Document 19

Non-licensed Document 20

Non-licensed Document 21

[0057] Support for various services using SL communication (also known as PC5 communication) is being considered in both EPS and 5G core systems (see Non-Patent Documents 1, 16, 20, 21, 22, and 23). In SL communication, communication takes place between terminals. In SL communication, not only direct communication between terminals but also communication between the UE and the NW via relays has been proposed (see Non-Patent Documents 20 and 23). In such relay-mediated communication, the problem is how to reduce the power consumption of the terminals.

[0058] In view of the above issues, one of the objectives of this disclosure is to reduce power consumption in communication systems that utilize terminal-to-terminal communication. [Means for solving the problem]

[0059] The communication system according to this disclosure is a communication system comprising a base station, a first communication terminal configured to perform wireless communication with the base station, and a second communication terminal configured to perform terminal-to-terminal communication with the first communication terminal, wherein the first communication terminal is configured to relay communication between the second communication terminal and the base station, and if there is no data to be transmitted or received between the second communication terminal and the base station for a predetermined period of time, the first communication terminal releases its connection with the base station and transitions to an idle state. The communication terminal relating to this disclosure is a communication terminal configured to perform wireless communication with a base station, wherein the communication terminal is configured to perform terminal-to-terminal communication with other communication terminals and is configured to relay communication between the other communication terminals and the base station, and is characterized in that if there is no data to be transmitted or received between the other communication terminals and the base station for a predetermined period of time, the communication terminal releases its connection with the base station and transitions to an idle state. [Effects of the Invention]

[0060] According to this disclosure, power consumption can be reduced in a communication system that utilizes terminal-to-terminal communication.

[0061] The purpose, features, aspects, and advantages of this disclosure will become clearer from the following detailed description and accompanying drawings. [Brief explanation of the drawing]

[0062] [Figure 1] This is an explanatory diagram showing the configuration of wireless frames used in LTE communication systems. [Figure 2] This block diagram shows the overall configuration of the LTE communication system 200 as discussed in 3GPP. [Figure 3] This is a block diagram showing the overall configuration of the NR communication system 210 as discussed in 3GPP. [Figure 4] This is a diagram illustrating the configuration of a data center using eNBs and gNBs connected to the EPC. [Figure 5] This is a diagram showing the configuration of the DC using gNB connected to the NG core. [Figure 6] This is a diagram showing the configuration of the DC with eNBs and gNBs connected to the NG core. [Figure 7] This is a diagram showing the configuration of the DC with eNBs and gNBs connected to the NG core. [Figure 8] Figure 2 is a block diagram showing the configuration of the mobile terminal 202. [Figure 9] Figure 2 is a block diagram showing the configuration of base station 203. [Figure 10] This block diagram shows the configuration of MME. [Figure 11] This is a block diagram showing the configuration of 5GC. [Figure 12] This is a flowchart illustrating the general process from cell search to standby operation performed by a communication terminal (UE) in an LTE communication system. [Figure 13] This figure shows an example of a cell configuration in an NR system. [Figure 14] This sequence diagram shows an example of a method for communication between a UE and a NW via a relay UE in Embodiment 1. [Figure 15] This sequence diagram shows an example of a method for communication between a UE and a NW via a relay UE in Embodiment 1. [Figure 16] This sequence diagram shows an example of a method for communication between a UE and a NW via a relay UE in Embodiment 1. [Figure 17] This sequence diagram shows an example of a method for communicating between a UE and a NW via a relay UE, in a modified example of Embodiment 1. [Figure 18] This sequence diagram shows an example of a method for communicating between a UE and a NW via a relay UE, in a modified example of Embodiment 1. [Figure 19] This sequence diagram shows an example of a method for communicating between a UE and a NW via a relay UE, in a modified example of Embodiment 1. [Figure 20] This sequence diagram shows an example of a method for communicating between a UE and a NW via a relay UE, as shown in a modified example 2 of Embodiment 1. [Figure 21] This sequence diagram shows an example of a method for communicating between a UE and a NW via a relay UE, as shown in a modified example 2 of Embodiment 1. [Figure 22] This sequence diagram shows an example of a method for communicating between a UE and a NW via a relay UE, as shown in a modified example 2 of Embodiment 1. [Figure 23]This sequence diagram shows an example of a method for communication between the UE and the NW via a relay UE in Embodiment 3. [Figure 24] This sequence diagram shows an example of a method for communication between the UE and the NW via a relay UE in Embodiment 3. [Figure 25] This sequence diagram shows an example of a method for communicating between a UE and a NW via a relay UE, in a modified example of Embodiment 3, Part 1. [Figure 26] This sequence diagram shows an example of a method for communicating between a UE and a NW via a relay UE, in a modified example of Embodiment 3, Part 1. [Figure 27] This sequence diagram shows an example of a method for notifying the remote UE, the relay UE, and the gNB connected to the relay UE of information regarding communication between the remote UE and the NW via the relay UE, in a modified example 1 of Embodiment 3. [Figure 28] This is a conceptual diagram showing a first example of the PC5 DRX settings for Embodiment 4. [Figure 29] This is a conceptual diagram showing a second example of the PC5 DRX settings for Embodiment 4. [Figure 30] This is a conceptual diagram showing a third example of the PC5 DRX configuration for Embodiment 4. [Figure 31] This is a conceptual diagram showing a fourth example of the PC5 DRX configuration for Embodiment 4. [Figure 32] This sequence diagram shows a first example of a method for aligning DRX in both directions during direct communication between UEs at PC5 in Embodiment 4. [Figure 33] This sequence diagram shows a first example of a method for aligning DRX in both directions during direct communication between UEs at PC5 in Embodiment 4. [Figure 34] This sequence diagram shows a second example of a method for aligning DRX in both directions during direct communication between UEs at PC5 in Embodiment 4. [Figure 35] This sequence diagram shows a second example of a method for aligning DRX in both directions during direct communication between UEs at PC5 in Embodiment 4. [Figure 36] This sequence diagram shows an example of a method for configuring PC5 DRX settings between a remote UE and a relay UE during communication between a remote UE and a network via a relay UE, according to Embodiment 4. [Figure 37] This sequence diagram shows an example of a method for configuring PC5 DRX settings between a remote UE and a relay UE during communication between a remote UE and a network via a relay UE, according to Embodiment 4. [Modes for carrying out the invention]

[0063] Embodiment 1. Figure 2 is a block diagram showing the overall configuration of the LTE communication system 200 being discussed in 3GPP. Figure 2 will be explained below. The radio access network is called E-UTRAN (Evolved Universal Terrestrial Radio Access Network) 201. The mobile terminal equipment (hereinafter referred to as "User Equipment: UE") 202, which is a communication terminal device, can communicate wirelessly with the base station equipment (hereinafter referred to as "Base Station (E-UTRAN NodeB: eNB)") 203 and transmits and receives signals wirelessly.

[0064] Here, "communication terminal equipment" includes not only mobile terminal equipment such as portable mobile phone terminals, but also stationary devices such as sensors. In the following explanation, "communication terminal equipment" may sometimes be simply referred to as "communication terminal."

[0065] If the control protocol for the mobile terminal 202, such as RRC (Radio Resource Control), and the user plane (hereinafter sometimes referred to as U-Plane), such as PDCP (Packet Data Convergence Protocol), RLC (Radio Link Control), MAC (Medium Access Control), and PHY (Physical layer), are terminated at base station 203, then E-UTRAN is composed of one or more base stations 203.

[0066] The control protocol RRC (Radio Resource Control) between the mobile terminal 202 and the base station 203 performs functions such as broadcasting, paging, and RRC connection management. The states of the base station 203 and the mobile terminal 202 in RRC are RRC_IDLE and RRC_CONNECTED.

[0067] In RRC_IDLE mode, tasks such as PLMN (Public Land Mobile Network) selection, System Information (SI) notification, paging, cell re-selection, and mobility are performed. In RRC_CONNECTED mode, mobile terminals have an RRC connection and can send and receive data with the network. In RRC_CONNECTED mode, tasks such as handover (HO) and neighbor cell measurement are also performed.

[0068] Base station 203 consists of one or more eNB207 units. The system, comprising the core network EPC (Evolved Packet Core) and the wireless access network E-UTRAN201, is called EPS (Evolved Packet System). The EPC and E-UTRAN201 are sometimes collectively referred to as the "network."

[0069] The eNB207 is connected via an S1 interface to a Mobility Management Entity (MME), or a Serving Gateway (S-GW), or an MME / S-GW unit (hereinafter sometimes referred to as "MME unit") 204 that includes both an MME and an S-GW, and control information is communicated between the eNB207 and the MME unit 204. Multiple MME units 204 may be connected to a single eNB207. The eNB207s are connected to each other via an X2 interface, and control information is communicated between the eNB207s.

[0070] The MME unit 204 controls the connection between the higher-level device, specifically the higher-level node, which is the base station eNB 207, and the mobile terminal (UE) 202. The MME unit 204 constitutes the core network EPC. The base station 203 constitutes the E-UTRAN 201.

[0071] The base station 203 may constitute one cell or multiple cells. Each cell has a predetermined range called coverage, which is the range within which it can communicate with the mobile terminal 202, and wireless communication is performed with the mobile terminal 202 within that coverage. When one base station 203 constitutes multiple cells, each cell is configured to communicate with the mobile terminal 202.

[0072] Figure 3 is a block diagram showing the overall configuration of the 5G communication system 210 being discussed in 3GPP. Figure 3 will now be explained. The radio access network is called NG-RAN (Next Generation Radio Access Network) 211. UE 202 can communicate wirelessly with NR base station equipment (hereinafter referred to as "NR base station (NG-RAN NodeB: gNB)") 213 and transmits and receives signals wirelessly. The core network is called the 5G Core (5GC).

[0073] If the control protocol for UE202, such as RRC (Radio Resource Control), and the user plane (hereinafter sometimes referred to as U-Plane), such as SDAP (Service Data Adaptation Protocol), PDCP (Packet Data Convergence Protocol), RLC (Radio Link Control), MAC (Medium Access Control), and PHY (Physical layer), are terminated at the NR base station 213, then the NG-RAN is composed of one or more NR base stations 213.

[0074] The functionality of the Radio Resource Control (RRC) control protocol between UE202 and NR base station 213 is the same as in LTE. The states of NR base station 213 and UE202 in RRC are RRC_IDLE, RRC_CONNECTED, and RRC_INACTIVE.

[0075] RRC_IDLE and RRC_CONNECTED are the same as in the LTE system. RRC_INACTIVE means that the connection between the 5G core and NR base station 213 is maintained while system information (SI) broadcasting, paging, cell re-selection, and mobility are performed.

[0076] The gNB217 is connected via an NG interface to an Access and Mobility Management Function (AMF), a Session Management Function (SMF), or a User Plane Function (UPF), or an AMF / SMF / UPF unit (hereinafter sometimes referred to as the "5GC unit") 214 that includes AMF, SMF, and UPF. Control information and / or user data are communicated between the gNB217 and the 5GC unit 214. The NG interface is a collective term for the N2 interface between the gNB217 and AMF, the N3 interface between the gNB217 and UPF, the N11 interface between AMF and SMF, and the N4 interface between UPF and SMF. Multiple 5GC units 214 may be connected to a single gNB217. The gNB217s are connected to each other via an Xn interface, and control information and / or user data are communicated between them.

[0077] Like base station 203, NR base station 213 may also consist of one or more cells. When one NR base station 213 consists of multiple cells, each cell is configured to communicate with UE 202.

[0078] The gNB217 may be divided into a Central Unit (CU) 218 ​​and a Distributed Unit (DU) 219. One CU218 is configured within the gNB217. One or more DU219s are configured within the gNB217. The CU218 is connected to the DU219 via an F1 interface, and control information and / or user data are communicated between the CU218 and the DU219.

[0079] In a 5G communication system, the Unified Data Management (UDM) function and Policy Control Function (PCF) described in Non-Patent Document 21 (3GPP TS23.501) may be included. The UDM and / or PCF may be included in the 5GC section in Figure 3.

[0080] In a 5G communication system, the Non-3GPP Interworking Function (N3IWF) described in Non-Patent Document 21 (3GPP TS23.501) may be included. In non-3GPP access between the UE and the N3IWF, the Access Network (AN) may be terminated between the UE and the UE.

[0081] Figure 4 shows the configuration of a DC with eNBs and gNBs connected to the EPC. In Figure 4, solid lines indicate U-Plane connections, and dashed lines indicate C-Plane connections. In Figure 4, eNB223-1 acts as the master base station, and gNB224-2 acts as the secondary base station (this DC configuration is sometimes referred to as EN-DC). Figure 4 shows an example where the U-Plane connection between the MME unit 204 and gNB224-2 is made via eNB223-1, but it may also be made directly between the MME unit 204 and gNB224-2.

[0082] Figure 5 shows the configuration of a DC with gNBs connected to the NG core. In Figure 5, solid lines indicate U-Plane connections, and dashed lines indicate C-Plane connections. In Figure 5, gNB224-1 acts as the master base station, and gNB224-2 acts as the secondary base station (this DC configuration is sometimes referred to as NR-DC). Figure 5 shows an example where the U-Plane connection between 5GC unit 214 and gNB224-2 is made via gNB224-1, but it may also be made directly between 5GC unit 214 and gNB224-2.

[0083] Figure 6 shows the configuration of a DC with eNBs and gNBs 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 acts as the master base station, and gNB224-2 acts as the secondary base station (this DC configuration is sometimes referred to as NG-EN-DC). Figure 6 shows an example where the 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.

[0084] Figure 7 shows another configuration of a DC with eNBs and gNBs 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 acts as the master base station, and eNB226-2 acts as the secondary base station (this DC configuration is sometimes referred to as NE-DC). Figure 7 shows an example where the 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.

[0085] Figure 8 is a block diagram showing the configuration of the mobile terminal 202 shown in Figure 2. The transmission process of the mobile terminal 202 shown in Figure 8 will now be explained. First, control data from the protocol processing unit 301 and user data from the application unit 302 are stored in the transmission data buffer unit 303. The data stored in the transmission data buffer unit 303 is passed to the encoder unit 304, where encoding processing such as error correction is performed. There may be data that is output directly from the transmission data buffer unit 303 to the modulation unit 305 without undergoing encoding processing. The data encoded by the encoder unit 304 is then modulated in the modulation unit 305. Precoding in MIMO may be performed in the modulation unit 305. The modulated data is converted into a baseband signal, then output to the frequency conversion unit 306, where it is converted to a wireless transmission frequency. After that, the transmission signal is sent from antennas 307-1 to 307-4 to the base station 203. Figure 8 illustrates the case where there are four antennas, but the number of antennas is not limited to four.

[0086] Furthermore, the reception processing of the mobile terminal 202 is performed as follows: A radio signal from the base station 203 is received by antennas 307-1 to 307-4. The received signal is converted from the radio reception frequency to a baseband signal by the frequency conversion unit 306, and demodulation processing is performed by the demodulation unit 308. Weight calculation and multiplication processing may also be performed in the demodulation unit 308. The demodulated data is passed to the decoder unit 309, where decoding processing such as error correction is performed. Of the decoded data, the control data is passed to the protocol processing unit 301, and the user data is passed to the application unit 302. The series of processes of the mobile terminal 202 are controlled by the control unit 310. Therefore, although the control unit 310 is omitted in Figure 8, it is connected to each of the units 301 to 309. In Figure 8, the number of antennas used by the mobile terminal 202 for transmission and the number of antennas used for reception may be the same or different.

[0087] Figure 9 is a block diagram showing the configuration of the base station 203 shown in Figure 2. The transmission process of the base station 203 shown in Figure 9 will now be explained. The EPC communication unit 401 transmits and receives data between the base station 203 and the EPC (MME unit 204, etc.). The 5GC communication unit 412 transmits and receives data between the base station 203 and the 5GC (5GC unit 214, etc.). 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. Control data from the protocol processing unit 403, as well as 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.

[0088] The data stored in the transmission data buffer unit 404 is passed to the encoder unit 405, where it undergoes encoding processing such as error correction. Some data may be output directly from the transmission data buffer unit 404 to the modulation unit 406 without undergoing encoding processing. The encoded data is then modulated in the modulation unit 406. Precoding in MIMO may be performed in the modulation unit 406. The modulated data is converted to a baseband signal, then output to the frequency conversion unit 407, where it is converted to a wireless transmission frequency. Subsequently, the transmission signal is sent from antennas 408-1 to 408-4 to one or more mobile terminals 202. Figure 9 illustrates the case with four antennas, but the number of antennas is not limited to four.

[0089] Furthermore, the reception processing of the base station 203 is performed as follows: A radio signal from one or more mobile terminals 202 is received by the antenna 408. The received signal is converted from the radio reception frequency to a baseband signal by the frequency conversion unit 407, and demodulation processing is performed by the demodulation unit 409. The demodulated data is passed to the decoder unit 410, where decoding processing such as error correction is performed. Of the decoded data, the 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, while the user data is passed to the 5GC communication unit 412, the EPC communication unit 401, and the other base station communication unit 402. The series of processes of the base station 203 are controlled by the control unit 411. Therefore, although the control unit 411 is omitted in Figure 9, it is connected to each of the units 401 to 410. In Figure 9, the number of antennas used by the base station 203 for transmission and the number of antennas used for reception may be the same or different.

[0090] Figure 9 is a block diagram showing the configuration of base station 203, but base station 213 may have a similar configuration. Also, in Figures 8 and 9, the number of antennas on mobile terminal 202 and base station 203 may be the same or different.

[0091] Figure 10 is a block diagram showing the configuration of the MME. Figure 10 shows the configuration of the MME204a included in the MME unit 204 shown in Figure 2 above. The PDN GW communication unit 501 transmits and receives data between the MME204a and the PDN GW. The base station communication unit 502 transmits and receives data between the MME204a and the base station 203 via the S1 interface. 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 the 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.

[0092] 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.

[0093] The control plane control unit 505 includes the NAS security unit 505-1, the SAE bearer control unit 505-2, and the idle state mobility management unit 505-3, and performs all processing for the control plane (hereinafter sometimes referred to as C-Plane). The NAS security unit 505-1 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 standby state (also referred to as LTE-IDLE state or simply idle), generation and control of paging signals in the standby state, addition, deletion, updating, searching, and tracking area list management for one or more mobile terminals 202 under its umbrella.

[0094] The MME204a distributes paging signals to one or more base stations 203. The MME204a also performs mobility control in the idle state. The MME204a manages the tracking area list when the mobile terminal is in the idle state and when it is in the active state. The MME204a initiates the paging protocol by sending paging messages to cells belonging to the registered tracking area of ​​the UE. The management of the CSG, CSG ID, and whitelist of the eNB207 connected to the MME204a may be performed by the idle state mobility management unit 505-3.

[0095] Figure 11 is a block diagram showing the configuration of the 5GC. Figure 11 shows the configuration of the 5GC unit 214 shown in Figure 3. Figure 11 shows the case where the 5GC unit 214 shown in Figure 5 includes the configurations of AMF, SMF, and UPF. 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 station 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.

[0096] 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 base station 203 and / or base station 213 is control data, the control data is passed from 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.

[0097] The control plane control unit 525 includes the NAS security unit 525-1, the PDU session control unit 525-2, and the idle state mobility management unit 525-3, and performs all processing for the control plane (hereinafter sometimes referred to as C-Plane). The NAS security unit 525-1 performs security for NAS (Non-Access Stratum) messages, etc. The PDU session control unit 525-2 manages 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 standby state (also referred to as RRC_IDLE state or simply idle), generation and control of paging signals in the standby state, addition, deletion, updating, searching, and tracking area list management for one or more mobile terminals 202 under its umbrella.

[0098] 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 the idle state. The 5GC unit 214 manages the tracking area list when the mobile terminal is in the idle state, inactive state, and active state. The 5GC unit 214 initiates the paging protocol by sending a paging message to a cell belonging to the tracking area where the UE is registered.

[0099] Next, an example of a cell search method in a communication system is shown. Figure 12 is a flowchart illustrating 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 the slot timing and frame timing using the first synchronization signal (P-SS) and the second synchronization signal (S-SS) transmitted from the surrounding base station.

[0100] P-SS and S-SS together are called the Synchronization Signal (SS). Each PCI assigned to a cell has a synchronization code that corresponds one-to-one with that PCI. 504 different PCI combinations are being considered. These 504 PCI combinations are used for synchronization, and the PCI of the synchronized cell is detected (identified).

[0101] Next, for the synchronized cell, step ST602 detects the cell-specific reference signal (CRS), which is a reference signal (RS) transmitted from the base station to each cell, and measures the received power (RSRP) of the RS. The reference signal (RS) uses a code that corresponds one-to-one with the PCI. By correlating with this code, it is possible to isolate it from other cells. By deriving the code for the RS of the cell from the PCI identified in step ST601, it becomes possible to detect the RS and measure the received power of the RS.

[0102] Next, in step ST603, from among the one or more cells detected up to step ST602, the cell with the best RS reception quality, for example, the cell with the highest RS reception power, i.e., the best cell, is selected.

[0103] Next, in step ST604, the PBCH of the best cell is received to obtain the broadcast information, which is the BCCH. The BCCH on the PBCH is mapped to the MIB (Master Information Block), which contains cell configuration information. Therefore, by receiving the PBCH and obtaining the BCCH, the MIB can be obtained. MIB information includes, for example, the DL (downlink) system bandwidth (also called transmission bandwidth configuration: dl-bandwidth), the number of transmitting antennas, and the SFN (System Frame Number).

[0104] Next, in step ST605, the DL-SCH of the cell is received based on the cell configuration information of the MIB, and SIB (System Information Block) 1 is obtained from the broadcast information BCCH. SIB1 contains information about accessing the cell, information about cell selection, and scheduling information for other SIBs (SIBk; an integer k ≥ 2). SIB1 also contains the Tracking Area Code (TAC).

[0105] 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 already held by the communication terminal. The Tracking Area List is also called the TAI list. TAI is identification information for identifying a tracking area and consists of MCC (Mobile Country Code), MNC (Mobile Network Code), and TAC (Tracking Area Code). MCC is the country code. MNC is the network code. TAC is the code number of the tracking area.

[0106] If, as a result of the comparison in step ST606, the TAC received in step ST605 is the same as a TAC included in the tracking area list, the communication terminal enters a waiting state in that cell. If, after comparison, the TAC received in step ST605 is not included in the tracking area list, the communication terminal requests a change in the tracking area through that cell to the Core Network (EPC), which includes the MME, etc., in order to perform a Tracking Area Update (TAU).

[0107] In the example shown in Figure 12, an example of the operation from cell search to standby in the LTE system is shown. However, in the NR system, in step ST603, the best beam may be selected in addition to the best cell. Also in the NR system, in step ST604, beam information, such as a beam identifier, may be obtained. Also in the NR system, in step ST604, scheduling information for the Remaining Minimum SI (RMSI) may be obtained. In the NR system, in step ST605, the RMSI may be received.

[0108] The devices constituting the core network (sometimes referred to as "core network devices") update the tracking area list based on the identification number (UE-ID, etc.) of the communication terminal sent from the communication terminal along with the TAU request signal. The core network devices send the updated tracking area list to the communication terminal. The communication terminal rewrites (updates) its TAC list based on the received tracking area list. After that, the communication terminal enters a waiting state in that cell.

[0109] The proliferation 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. To address this, efforts are being made to improve frequency utilization efficiency by reducing the number of cells and promoting spatial separation.

[0110] In conventional cell configurations, cells composed of eNBs have relatively wide coverage. Traditionally, cells are configured to cover a certain area through the relatively wide coverage of multiple cells composed of multiple eNBs.

[0111] When subdivided into smaller cells, the cells composed of eNBs have narrower coverage than cells composed of conventional eNBs. Therefore, as before, a larger number of subdivided eNBs are needed to cover a given area compared to conventional eNBs.

[0112] In the following explanation, cells with relatively high coverage, such as those composed of conventional eNBs, will be referred to as "macrocells," and the eNBs that make up macrocells will be referred to as "macro eNBs." Similarly, cells with relatively low coverage, such as those that have been resized into smaller cells, will be referred to as "small cells," and the eNBs that make up small cells will be referred to as "small eNBs."

[0113] Macro eNB may be, for example, a "Wide Area Base Station" as described in Non-Patent Document 7.

[0114] A small eNB may be, for example, a low-power node, a local area node, or a hotspot. Alternatively, a small eNB may be a pico eNB constituting a picocell, a femto eNB constituting a femtocell, a HeNB, an RRH (Remote Radio Head), an RRU (Remote Radio Unit), an RRE (Remote Radio Equipment), or an RN (Relay Node). Furthermore, a small eNB may be a "Local Area Base Station" or "Home Base Station" as described in Non-Patent Document 7.

[0115] Figure 13 shows an example of a cell configuration in NR. In an NR cell, a narrow beam is formed and transmitted by changing its direction. In the example shown in Figure 13, base station 750 uses beam 751-1 to transmit and receive with a mobile terminal at a certain time. At other times, base station 750 uses beam 751-2 to transmit and receive with a mobile terminal. Similarly, base station 750 uses one or more of beams 751-3 to 751-8 to transmit and receive with a mobile terminal. In this way, base station 750 configures a wide-area cell.

[0116] Figure 13 shows an example where the base station 750 uses eight beams, but the number of beams may be different from eight. Also, in the example shown in Figure 13, the base station 750 uses one beam simultaneously, but it may use multiple beams.

[0117] In 3GPP, Side Link (SL) is supported for D2D (Device to Device) and V2V (Vehicle to Vehicle) communication (see Non-Patent Documents 1 and 16). SL is defined by the PC5 interface.

[0118] The physical channels used in SL (see Non-Patent Document 1) are described below. The Physical Sidelink Broadcast Channel (PSBCH) carries system and synchronization-related information and is transmitted from the UE.

[0119] The Physical Sidelink Discovery Channel (PSDCH) carries sidelink discovery messages from the UE (Union Engine).

[0120] The Physical Sidelink Control Channel (PSCCH) carries control information from the UE for sidelink communication and V2X sidelink communication.

[0121] The Physical Sidelink Shared Channel (PSSCH) carries data from the UE for sidelink communication and V2X sidelink communication.

[0122] The Physical Sidelink Feedback Channel (PSFCH) carries HARQ feedback over the sidelink from the UE that received the PSSCH transmission to the UE that transmitted the PSSCH.

[0123] The transport channels used in SL (see Non-Patent Document 1) are described below. The Sidelink broadcast channel (SL-BCH) has a predetermined transport format and is mapped to the physical channel PSBCH.

[0124] The Sidelink Discovery Channel (SL-DCH) has periodic broadcast transmissions in a fixed size and predetermined format. The SL-DCH supports both UE autonomous resource selection and resource allocation scheduled by the eNB. UE autonomous resource selection carries a risk of collisions, while there are no collisions when the UE allocates individual resources via the eNB. The SL-DCH supports HARQ combining but not HARQ feedback. The SL-DCH is mapped to the physical channel PSDCH.

[0125] Sidelink shared channels (SL-SCH) support broadcast transmission. SL-SCH supports both UE autonomous resource selection and resource allocation scheduled by the eNB. UE autonomous resource selection carries a collision risk, while there is no collision when the UE allocates individual resources via the eNB. SL-SCH also supports HARQ combining but not HARQ feedback. Furthermore, SL-SCH supports dynamic link adaptation by changing transmit power, modulation, and coding. SL-SCH is mapped to the physical channel PSSCH.

[0126] This section describes the logical channels used in SL (see Non-Patent Document 1). The Sidelink Broadcast Control Channel (SBCCH) is a sidelink channel used to broadcast sidelink system information from one UE to another. The SBCCH is mapped to the transport channel SL-BCH.

[0127] A Sidelink Traffic Channel (STCH) is a one-to-many sidelink traffic channel for transmitting user information from one UE to another. STCH is used only between UEs with sidelink communication capabilities and UEs with V2X sidelink communication capabilities. One-to-one communication between two UEs with sidelink communication capabilities is also achieved via STCH. STCH is mapped to the transport channel SL-SCH.

[0128] The Sidelink Control Channel (SCCH) is a sidelink control channel used to transmit control information from one UE to another. The SCCH is mapped to the transport channel SL-SCH.

[0129] 3GPP is considering supporting V2X communication in NR as well. The study of V2X communication in NR is progressing 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.

[0130] In LTE, SL communication was limited to broadcast only. In NR, support for unicast and groupcast in addition to broadcast is being considered for SL communication (see Non-Patent Document 22 (TS23.287)).

[0131] Support for HARQ feedback (Ack / Nack) and CSI reporting is being considered for unicast and groupcast communications.

[0132] In SL communication, in addition to broadcast, support for unicast and groupcast is being considered, and therefore support for PC5-S signaling is being explored (see Non-Patent Document 22 (TS23.287)). For example, PC5-S signaling is implemented to establish a link for SL, i.e., PC5 communication. This link is implemented at the V2X layer and is also referred to as a Layer 2 link.

[0133] Furthermore, support for RRC signaling in SL communication is being considered (see Non-Patent Document 22 (TS23.287)). RRC signaling in SL communication is also referred to as PC5 RRC signaling. For example, it has been proposed to notify UEs of their capabilities between UEs performing PC5 communication, and to notify AS layer settings for performing V2X communication using PC5 communication.

[0134] In SL communication, communication between the UE and the NW via a relay has been proposed (see Non-Patent Documents 20 and 23). The relay between the UE and the NW is sometimes referred to as a UE-to-NW relay or a UE-to-NW relay. In this disclosure, the UE that implements the relay between the UE and the NW may be referred to as a relay UE.

[0135] 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 located further away from the RAN node. In such cases, a method using UE-to-Network relays can be considered. For example, communication between the gNB and a UE (sometimes referred to as a remote UE) can be performed via a relay UE. Communication between the gNB and the relay UE is performed using Uu, and communication between the relay UE and the remote UE is performed using PC5.

[0136] Conventionally, in 5G systems, a PDU session is established between the UE and the NW for communication. However, in UE-NW relay, communication between the UE and the NW is performed via a relay UE, so the conventional method cannot be applied. This document discloses the PDU session when communication between the UE and the NW is performed via a relay UE.

[0137] A PDU session is established between the relay UE and the network. A PDU session is established between the relay UE and the CN-side node. The CN-side node may be a UPF. A PDU session may also be established between the relay UE and the data network (DN). A PC5-S link is established between the relay UE and the remote UE. Communication is performed between the UE and the network via the relay UE using the PDU session and the PC5-S link.

[0138] A PDU session for relaying is established between the relay UE and the CN node. A PC5-S link is established between the relay UE and the remote UE. The relay UE notifies the AMF or SMF of information about the relay UE. This may be done during the PDU session establishment process. 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 information about the relay UE and the remote UE include the UE identifier and IP information. The IP information may be an IP address. Another specific example of information about the remote UE is information about the PC5-S link between the remote UE and the relay UE. Information about the PC5-S link may be, for example, the PC5-S link identifier, the source UE identifier, the destination UE identifier, PC5 QoS flow information, PC5 QoS flow identifier, SLRB configuration information, and SLRB identifier. Combinations of these may also be included.

[0139] The IP address of the remote UE may be IPv4. This avoids complexity in the device design. The IP address of the remote UE may also be IPv6. This allows a large number of UEs to be accommodated in the communication network.

[0140] The relay UE may store information about the remote UE. The AMF / SMF may also store information about the remote UE. Information about the remote UE may be associated with the relay UE. Information about the remote UE may be stored in association with the relay UE. Information about the remote UE may be associated with a PDU session established between the relay UE and the network. Information about the remote UE may be stored in association with a PDU session established between the relay UE and the network. For example, information about the remote UE may be stored in the context of the relay UE. By associating information about the remote UE with the relay UE, or by associating information about the remote UE with a PDU session established between the relay UE and the network, the AMF / SMF can recognize, for example, that it is a PDU session for relaying to the remote UE, rather than simply a PDU session between the relay UE and the network interface (CN).

[0141] The AMF / SMF notifies the UPF of information regarding the remote UE. The UPF can then recognize the information regarding the remote UE. The information regarding the remote UE may also be notified in association with the relay UE. Furthermore, the information regarding the remote UE may also be notified in association with the PDU session established between the relay UE and the network. By associating the information regarding the remote UE with the relay UE and the PDU session established between the relay UE and the network, the UPF can recognize, for example, that it is a PDU session for relaying to the remote UE, rather than simply a PDU session between the relay UE and the network controller (CN).

[0142] In this way, the PDU session between the relay UE and the network is associated with the PC5-S link between the relay UE and the remote UE.

[0143] The relay UE acts as a router for the remote UE, forwarding the PC5-S link between the remote UE and the relay UE, and the PDU session between the relay UE and the network. Information about the remote UE may be used in this forwarding.

[0144] This allows data communication between the remote UE and the UPF via the relay UE.

[0145] As mentioned above, communication between the remote UE and the network via the relay UE takes place when a PDU session is established between the relay UE and the network. The relay UE must maintain a connection with the network. Furthermore, communication between the remote UE and the network via the relay UE takes place when a PC5-S link is established between the remote UE and the relay UE. The remote UE must maintain a connection with the relay UE. For this reason, power consumption of both the relay UE and the remote UE increases during communication between the remote UE and the network via the relay UE.

[0146] Terminals that perform SL communication are not only intended to be mounted in vehicles, but are also envisioned to be carried by pedestrians. Such terminals have limited battery capacity. Furthermore, even if a terminal has a large battery, low power consumption of the terminal is required to build an ecological society. Therefore, reducing the power consumption of relay UEs and remote UEs in SL communication terminals, such as in communication between a remote UE and a network via a relay UE, becomes a challenge.

[0147] We will disclose methods for solving these problems.

[0148] For relay UEs with UE-to-NW relay capabilities, transition to RRC_Idle is permitted. For relay UEs with UE-to-NW relay capabilities, transition to CM_Idle may also be permitted. In other words, the RRC connection between the relay UE and the gNB may be released. The PDU session between the relay UE and the NW may be released. The aforementioned transitions and releases may occur even if a PC5-S link is established between the remote UE and the relay UE.

[0149] An RRC release process is performed between the gNB and the relay UE. The gNB may initiate an RRC release to the relay UE. The relay UE may request an RRC release from the gNB. Upon receiving an RRC release request, the gNB performs the RRC release process with the relay UE. In addition, if the AMF performs a PDU session release process to the gNB, the gNB may perform the RRC release process with the relay UE. This makes it possible to transition the relay UE to the RRC_Idle state, which helps to reduce the power consumption of the relay UE.

[0150] The relay UE and the network nodes may perform the PDU session release process. The network nodes may include gNB, AMF, SMF, and UPF. The network nodes may also include DN (Data Network). The AMF may initiate the PDU session release process between the relay UE and the network. The SMF may request the release of the PDU session from the AMF. The UPF may request the release of the PDU session from the AMF via the SMF. The relay UE may request the release of the PDU session from the AMF. Upon receiving the PDU session release request, the AMF performs the PDU session release process between the relay UE and the network. This makes it possible to free up the resources used for the PDU session in the relay UE. This allows for lower power consumption of the relay UE and improves the efficiency of wireless resource utilization.

[0151] The AMF performs the release (disconnection) process of the CM connection between the relay UE and the NW. The AMF may initiate the release of the CM connection. The relay UE may request the AMF to release the CM connection. The gNB may request the AMF to release the CM connection with the relay UE. Upon receiving a request to release the CM connection, the AMF performs the release process of the CM connection with the relay UE. The AMF may also perform the CM connection release process when it receives a request to release a PDU session. In this way, it is possible to transition the relay UE to the CM_Idle state. This makes it possible to reduce the power consumption of the relay UE.

[0152] The RRC connection release, PDU session release, and CM connection release processes described above may be performed individually. Performing some or all of these release processes can reduce the power consumption of the relay UE.

[0153] It is preferable to perform the aforementioned release process with the PC5-S link between the relay UE and the remote UE connected. Alternatively, it is preferable to perform the aforementioned release process without releasing the PC5-S link between the relay UE and the remote UE.

[0154] For example, the aforementioned release process should be performed when communication between the remote UE and the network is temporarily interrupted. Also, for example, when communication between the remote UE and the network occurs periodically, the aforementioned release process should be performed during periods when such communication is not occurring. For example, when service data communication between the remote UE and the network is interrupted, only the PDU session release process may be performed. For example, when service data communication between the remote UE and the network is interrupted, the PDU session release process, RRC connection release process, and CM connection release process may also be performed. For example, when service data communication and data communication including signaling are interrupted between the remote UE and the network, the PDU session release process, RRC connection release process, and CM connection release process may be performed. By performing the aforementioned release process, releasing the connection between the relay UE and the network, and transitioning the relay UE to the RRC_Idle or CM_Idle state, the power consumption of the relay UE can be reduced.

[0155] The method for determining whether to perform or request release processing at relay UEs and network nodes, as described above, is disclosed. If there is no data for a PDU session for a predetermined period of time, the method for determining whether to perform or request release processing is disclosed.

[0156] The predetermined period may be statically determined by a standard or similar specification. Alternatively, the predetermined period may be configurable by the network node. The predetermined period may also be quasi-statically configurable. For example, the AMF or PCF may set the predetermined period. For example, the AMF may set the predetermined period using the QoS when establishing a PDU session. A node that has set the predetermined period notifies each node of the set predetermined period.

[0157] A relay UE or NW node may measure time information regarding data communication in a PDU session. For example, a relay UE or NW node may measure when data communication occurred in a PDU session. For example, a relay UE or NW node may measure the time elapsed since data was communicated in a PDU session. A relay UE or NW node may derive a traffic pattern from the measured time information regarding data communication. This derivation may be performed, for example, using statistical processing.

[0158] The measurement results may be stored on the node where the measurement was performed. Alternatively, the measurement results may be notified to other network nodes or servers. Other network nodes or servers may derive traffic patterns from the measurement results. The node that has derived the traffic patterns may notify relay UEs and network nodes of the derived traffic patterns.

[0159] In this way, relay UEs and network nodes can obtain time information regarding data communication in PDU sessions. Relay UEs and network nodes can then use this time information to determine if there is no data for a predetermined period of time.

[0160] A predetermined period may be set in a timer. For example, the timer is started when data is communicated in a PDU session. The timer is initialized each time new data is communicated. If there is no data communication and the timer expires, the release process described above is performed, or a request for the release process described above is made.

[0161] Other methods for determining whether to perform or request the aforementioned release process are disclosed. If there is no data on the PC5-S link for a specified period, the decision to perform or request the aforementioned release process is made.

[0162] The predetermined period may be statically determined by a standard or similar specification. Alternatively, the predetermined period may be configurable by the network node. The predetermined period may also be quasi-statically configurable. For example, the AMF or PCF may set the predetermined period. For example, the AMF may set the predetermined period using the QoS of the service communicated between the remote UE and the network. The node that has set the predetermined period notifies the relay UE or remote UE of the set predetermined period.

[0163] A relay UE or remote UE may measure time information regarding data communication on the PC5-S link. For example, a relay UE or remote UE may measure when data communication occurred on the PC5-S link. For example, a relay UE or remote UE may measure the time elapsed since data was communicated on the PC5-S link. A relay UE or remote UE may derive a traffic pattern from the measured time information regarding data communication. This derivation may be performed, for example, using statistical processing.

[0164] The measurement results may be stored in the relay UE or remote UE that performed the measurement. Alternatively, the measurement results may be notified from the remote UE to other network nodes or servers via the relay UE. Alternatively, the measurement results may be notified from the relay UE to other network nodes or servers. The other network nodes or servers may derive a traffic pattern from the measurement results. The node that has derived a traffic pattern may notify the remote UE or relay UE of the derived traffic pattern.

[0165] In this way, remote UEs and relay UEs can obtain time information regarding data communication on the PC5-S link. The remote UEs and relay UEs can then use this time information to determine if there is no data for a predetermined period of time.

[0166] A predetermined period may be set in a timer. For example, the timer is started when data is communicated via the PC5-S link. The timer is initialized each time new data is communicated. If there is no data communication and the timer expires, the aforementioned release process is performed, or a request for the aforementioned release process is made.

[0167] As mentioned above, the predetermined period set in the PDU session and the predetermined period set in the PC5-S link may be different. This allows for flexible settings depending on the timing of each communication. Alternatively, these predetermined periods may be set to the same value. This makes it possible to set the same value for both the PC5-S link and the PDU session, depending on the service performing communication between the remote UE and the network. This also simplifies the aforementioned release process. By setting these predetermined periods to the same value, for example, a relay UE that has established a PC5-S link and a PDU session can manage these predetermined periods with a single timer. This avoids the complexity of the decision to transition to the aforementioned release process.

[0168] By doing this, if there is no data communication for a specified period, the relay UE can be switched to the RRC_Idle or CM_Idle state, thereby reducing the power consumption of the relay UE.

[0169] A remote UE may request an RRC release between the relay UE and the gNB. The remote UE may request the RRC release from either the relay UE or the gNB.

[0170] A remote UE may request the release of a PDU session between the relay UE and the NW. The remote UE may request the release of the said PDU session from the relay UE, gNB, AMF, SMF, UPF, or DN.

[0171] A remote UE may request the release of the CM connection between the relay UE and the NW. The remote UE may request the release of the CM connection from the relay UE, gNB, or AMF.

[0172] Because the remote UE recognizes the services that communicate with the network, it can easily determine when communication between the remote UE and the network will be temporarily interrupted. By requesting the aforementioned release process between the relay UE and the network, the remote UE can perform the transition process to the RRC_Idle or CM_Idle state of the relay UE, which is suitable for the communication service between the remote UE and the network.

[0173] To determine whether the aforementioned release process should be performed or requested at the remote UE, the method described above, which determines whether the release process should be performed or requested when there is no data on the PC5-S link for a predetermined period, should be appropriately applied. The presence or absence of data communication in the PDU session is determined by the presence or absence of data communication on the PC5-S link. This determination is valid because both the PC5-S link between the remote UE and the relay UE, and the PDU session between the relay UE and the network, are used for communication between the remote UE and the network.

[0174] In this way, if there is no data communication on the PC5-S link for a predetermined period, the remote UE can transition the relay UE to the RRC_Idle or CM_Idle state. This makes it possible to reduce the power consumption of the relay UE.

[0175] This document discloses a method for releasing the connection between a relay UE and a network when there is no data communication between the relay UE and the network. It also discloses the process of transitioning the relay UE to the RRC_Idle or CM_Idle state. When the relay UE is in the RRC_Idle or CM_Idle state, it is possible to notify the relay UE that data has been generated when data is generated for the relay UE. However, when the relay UE is in the RRC_Idle or CM_Idle state, it is not possible to notify the remote UE that data has been generated when data is generated from the AS (Application Server) or DN. Therefore, it becomes impossible to send data to the remote UE via the relay UE.

[0176] We will disclose methods for solving these problems.

[0177] In the aforementioned communication method between the remote UE and the network, the AMF may store information about the remote UE in association with the relay UE. Information associating the relay UE and the remote UE may be provided. In this disclosure, information associating the relay UE and the remote UE may simply be referred to as association information. The remote UE associated with the relay UE may be the remote UE that communicates with the network and with which the relay UE has established a PDU session. The remote UE associated with the relay UE may also be the remote UE with which the relay UE has established a PC5-S link.

[0178] Multiple remote UEs may be associated with a single relay UE. This is effective when remote UEs communicate with the network via a single relay UE.

[0179] AMF may perform mobility management for remote UEs. AMF can perform mobility management for remote UEs by possessing relevant information about the remote UEs. AMF may also perform mobility management for remote UEs in conjunction with the mobility management of relay UEs, by associating them with relay UEs.

[0180] The association information may be a list. The association information may include information about each UE. This information may include, for example, an identifier, IP information, service type, slice information, etc. Information about remote UEs may also be included in the association information. The association information may be a list that uses the relay UE as an index, showing the associated remote UEs. Since AMF can create a list containing remote UEs as information elements of the relay UE from which remote UE association information has been obtained, it is possible to easily create such a list.

[0181] The association information may be a list that uses the remote UE as an index and shows the associated relay UEs. Since AMF can create a list that includes relay UEs as information elements for remote UEs, for example, when AMF receives a notification of data occurrence for a remote UE, it can easily find the relay UEs associated with that remote UE.

[0182] In communication between a remote UE and a network via a relay UE, a process for transitioning the relay UE to the RRC_Idle or CM_Idle state is disclosed. The AMF retains association information even when the relay UE is in the RRC_Idle or CM_Idle state.

[0183] Information regarding the remote UE may be updated as needed. When information regarding the remote UE is updated, the remote UE may notify the relay UE, AMF, or SMF of the updated information. The relay UE may also notify the AMF or SMF of the updated information regarding the remote UE. When information regarding the relay UE to which the remote UE is connected is updated, the remote UE may notify the AMF or SMF of the updated information. For example, when a relay UE newly connects to a remote UE, the relay UE may notify the AMF or SMF of the information regarding the remote UE. For example, when a relay UE receives updated information regarding the remote UE from the remote UE, it may notify the AMF or SMF of the updated information regarding the remote UE.

[0184] Furthermore, the relay UE may notify the AMF and SMF of information regarding the remote UE from which the connection with the relay UE has been released. The relay UE may also notify information indicating that the connection between the relay UE and the remote UE has been released.

[0185] AMF may use this updated information to update the association information.

[0186] AMF may include association information in the context information of the relay UE.

[0187] During the release process of a PDU session or the transition of a relay UE to the RRC_Idle or CM_Idle state, for example, gNB may request the AMF to release the relay UE context. When AMF receives a request to release the relay UE context, it performs the release process of the relay UE context. AMF then discards the relay UE context.

[0188] If association information is included in the context information of a relay UE, a problem arises where the association information is released along with the release of the relay UE's context. To avoid this, AMF should retain the relay UE's context information, including the association information, even when the relay UE enters the RRC_Idle or CM_Idle state. Alternatively, AMF should retain only the association information within the relay UE's context information even when the relay UE enters the RRC_Idle or CM_Idle state.

[0189] The context release message may include information indicating that some or all of the context information is retained. The retained context information may be association information. In this way, AMF can determine whether or not to retain the association information even if the relay UE enters the RRC_Idle or CM_Idle state.

[0190] As previously stated, the AMF creates and stores association information, but the relay UE or gNB may also create and store the association information. During the release process of a PDU session or the process of transitioning the relay UE to the RRC_Idle or CM_Idle state, the relay UE or gNB may notify the AMF or SMF of the association information. At that time, the relay UE or gNB may notify the updated latest association information. The AMF retains the updated latest association information even when the relay UE is in the RRC_Idle or CM_Idle state.

[0191] In this way, when a relay UE is in the RRC_Idle or CM_Idle state, for example, if data is generated for a remote UE and the AMF receives notification of the data generation for the remote UE, the AMF can easily detect the remote UE and the relay UE associated with it.

[0192] When the relay UE receives a signal indicating data generation to the remote UE while in the RRC_Idle or CM_Idle state, the AMF notifies the relay UE associated with the remote UE to paging. The AMF may use the aforementioned association information to discover the relay UE associated with the remote UE. The AMF notifies the relay UE to paging via the gNB connected to the relay UE.

[0193] The AMF may include information in the paging to the relay UE indicating that the paging is due to data generation to a remote UE. Alternatively, the AMF may include information about the remote UE in the paging to the relay UE. As information about the remote UE, the AMF may include, for example, the UE identifier in the paging to the relay UE. In this way, the relay UE can recognize that the paging is due to data generation to a remote UE.

[0194] A relay UE that receives paging establishes a PDU session with the network. If the relay UE receives information indicating that the paging is due to data being sent to a remote UE, it establishes a PDU session with the network. This PDU session may be for relay purposes. This PDU session may also be for communication with the remote UE that generated the data. In this way, a PDU session for communication between the remote UE and the network can be established between the relay UE and the network. Even after the relay UE has transitioned to the RRC_Idle or CM_Idle state, if data is sent to the remote UE, a PDU session can be established again between the relay UE and the network, and communication between the remote UE and the network can be enabled using this PDU session.

[0195] A relay UE that receives paging may transition to a connected state with the network. A relay UE that receives paging may transition to the RRC_Connected or CM_Connected state with the network. In this way, the state between the relay UE and the network becomes connected again, and communication between the remote UE and the network becomes possible via the relay UE.

[0196] If a relay UE that has received paging from the AMF is not connected to the remote UE to which the generated data is to be sent, the relay UE may notify the gNB or AMF that it is not connected to the remote UE to which the data is to be sent. The AMF may notify the SMF or UPF that the relay UE is not connected to the remote UE to which the data is to be sent. The UPF may notify the AS or DN that the relay UE is not connected to the remote UE to which the data is to be sent. It is also possible to indicate to the data source to the remote UE that the remote UE is not connected.

[0197] If the AMF receives information from the relay UE or gNB indicating that the relay UE is not connected to the remote UE to which the data is to be sent, it may update the association information. This eliminates the need to resend paging to the relay UE. This reduces the amount of signaling and reduces malfunctions in communication processing between the remote UE and the network via the relay UE.

[0198] The AMF disclosed that it notifies the relay UE of paging via the gNB. By using paging, the relay UE can perform intermittent reception (DRX). The relay UE can recognize whether or not data has been generated for the remote UE by receiving paging from the gNB at the paging period (which may be referred to in this disclosure as the paging DRX period).

[0199] By doing so, the relay UE can perform DRX, which enables lower power consumption for the relay UE.

[0200] Figures 14 to 16 are sequence diagrams illustrating an example of a method for communication between a UE and a NW via a relay UE in Embodiment 1. Figures 14 to 16 are connected at the boundary lines BL1415 and BL1516. Figures 14 to 16 disclose a method for transitioning the relay UE to the RRC_Idle or CM_Idle state when there is no data between the remote UE and the NW. In step ST1401, the relay UE performs the PDU session establishment process with the gNB, AMF, SMF, and UPF, and establishes a PDU session between the relay UE and the UPF. The relay UE may perform the PDU session establishment process before performing relay.

[0201] In step ST1402, a discovery process is performed between the remote UE and the relay UE to detect the data transmission destination. During this discovery process, the relay UE may notify information indicating that it has relay capability between the NW and the UE. Upon receiving this information, the remote UE can recognize that it can communicate with the NW via the relay UE.

[0202] In this discovery process, the remote UE may notify information indicating that it is searching for a relay UE between the network and the UE. The remote UE may notify information requesting a connection to the network. The remote UE may notify information requesting relay to the network. The remote UE may notify information indicating that the destination is the network. Upon receiving this information, the relay UE can recognize that the remote UE is requesting a connection to the network through its relay UE.

[0203] In step ST1403, a process is performed to establish a PC5 link between the remote UE and the relay UE. As a process to establish the PC5 link, for example, a PC5-S link establishment process is performed. A remote UE that has detected a relay UE for communication with the NW may perform the PC5-S link establishment process to the relay UE in step ST1403. This process establishes a PC5-S link between the remote UE and the relay UE. In this process, the remote UE may notify information requesting a 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 a connection to the NW via itself.

[0204] In step ST1404, the AS configuration may be communicated 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 the PC5 QoS flow between the remote UE and the relay UE, and the configuration of the SLRB that maps the PC5 QoS flow, may be performed using the QoS required for the service communicated between the remote UE and the network. For example, the remote UE derives QoS-related information corresponding to the service that has occurred. From the QoS-related information, the remote UE may configure the PC5 QoS flow and the PC5 QoS flow identifier. The remote UE also configures the SLRB for mapping the PC5 QoS flow. The remote UE may also configure the identifier for the SLRB configuration. In this way, PC5 communication that satisfies the QoS required for the service can be enabled.

[0205] The mapping information for QoS and SLRB settings may be pre-configured on the remote UE. If the remote UE is outside the coverage of the gNB, the remote UE should use the mapping information for QoS and SLRB settings that has been pre-configured within its own remote UE to perform the SLRB configuration.

[0206] QoS-related information may include PC5 QoS parameters (sometimes simply referred to as QoS parameters, omitting PC5). PC5 QoS parameters may include, for example, PQI (see Non-Patent Document 22 (TS23.287)). QoS-related information may also include QoS characteristics (see Non-Patent Document 22 (TS23.287)). PC5 QoS parameters and QoS characteristics may be collectively referred to as a QoS profile.

[0207] QoS-related information may include a PC5 QoS flow identifier (PQI). This identifier may be used to identify the QoS flow configured by the remote UE for data communication with the relay UE on the PC5.

[0208] As part of the PC5-S link establishment process, processing may be performed for establishing a PC5-S link from a remote UE to a relay UE, or for establishing a PC5-S link from a relay UE to a remote UE, or for establishing PC5-S links from a remote UE to a relay UE and from a relay UE to a remote UE.

[0209] The PC5-S link establishment process from the remote UE to the relay UE and the notification process for AS settings for SL communication from the remote UE to the relay UE may be performed after the PC5-S link establishment process from the remote UE to the relay UE and the notification process for AS settings for SL communication from the remote UE to the relay UE have been performed.

[0210] After the process for establishing the PC5-S link from the remote UE to the relay UE and from the relay UE to the remote UE has been completed, the AS setting for SL communication from the remote UE to the relay UE and the notification process for the AS setting for SL communication from the relay UE to the remote UE may be performed.

[0211] This enables bidirectional SL communication. As a result, communication from the remote UE to the relay UE and from the relay UE to the remote UE becomes possible.

[0212] In step ST1405, the remote UE notifies the AMF of remote UE-related information via the relay UE and gNB. In step ST1406, the AMF stores the remote UE-related information in the context of the relay UE in order to associate it with the relay UE. The AMF may also store information about the remote UE in association with the relay UE. The AMF may also store association information that links the relay UE and the remote UE.

[0213] In step ST1407, the AMF notifies the SMF of remote UE-related information. The AMF may also notify the SMF of association information between the relay UE and the remote UE. In step ST1408, the SMF notifies the UPF of remote UE-related information. is U The PF may also be notified of the association information between the relay UE and the remote UE. In this way, the UPF can recognize that the PDU session established with the relay UE is for relaying to the remote UE. For example, if DL data is generated for the remote UE, the UPF can send the DL data to the remote UE via the relay UE.

[0214] In step ST1409, UL data communication becomes possible between the remote UE and the UPF. Also, in step ST1410, DL data communication becomes possible between the UPF and the remote UE.

[0215] In step ST1411, the UPF determines whether or not data is being sent to the remote UE during communication between the remote UE and the network. For example, if no data is being sent for a predetermined period, the UPF may determine that no data is being sent. Having determined in step ST1411 that no data is being sent to the remote UE, the UPF in step ST1412 notifies the SMF of a request to release the PDU session between the relay UE and the network that is being used for communication between the remote UE and the network via the relay UE. The UPF may use association information between the remote UE and the relay UE to identify the PDU session between the relay UE and the network that is being used for communication between the remote UE and the network via the relay UE. The UPF can then determine which PDU session established between the relay UE and the network should be requested to be released for data to be sent to the remote UE.

[0216] In step ST1413, the SMF notifies the AMF of a request to release the PDU session between the relay UE and the network. In step ST1414, the AMF performs the PDU session release process between the relay UE and the network with the relay UE, gNB, SMF, and UPF. In step ST1415, the RRC connection release process is performed between the relay UE and gNB, and the CM connection release process is performed between the relay UE, gNB, and AMF. As a result, the relay UE transitions to the RRC_Idle or CM_Idle state. The relay UE, having transitioned to RRC_Idle or CM_Idle, begins receiving paging with the paging DRX setting announced by the gNB.

[0217] In step ST1416, the AMF holds remote UE-related information. The AMF holds association information linking the remote UE and the relay UE. Even after the relay UE has transitioned to the RRC_Idle or CM_Idle state, by holding the association information between the remote UE and the relay UE, it becomes possible to determine which relay UE should notify paging when data is generated or incoming to the remote UE, as described above.

[0218] In step ST1417, the UPF receives data from the AS or DN to the remote UE. In step ST1418, the UPF holds the data to the remote UE. In step ST1419, the UPF notifies the SMF of the data occurrence to the remote UE. Upon receiving this notification, the SMF may notify the UPF of the data occurrence notification in step ST1420. If there is no data occurrence notification response, the UPF may notify the remote UE of the data occurrence again. This can reduce malfunctions. In step ST1421, the SMF notifies the AMF of the data occurrence to the remote UE. Upon receiving this notification, the AMF may notify the SMF of the data occurrence notification in step ST1422. If there is no data occurrence notification response, the SMF may notify the remote UE of the data occurrence again. This can reduce malfunctions.

[0219] Upon receiving a data generation notification to a remote UE, the AMF uses the association information between the remote UE and the relay UE it has stored to identify which relay UE should be notified of the paging. In step ST1423, the AMF notifies the gNB connected to the identified relay UE of the paging. As mentioned above, the AMF may include information in the paging to indicate that it is paging to a remote UE. In step ST1424, the gNB notifies the relay UE of the paging. The gNB may include information in the paging to indicate that it is paging to a remote UE.

[0220] Upon receiving the paging, the relay UE performs the PDU session establishment process in step ST1425. It may also perform a service request process. The service request process causes the relay UE to perform the PDU session establishment process. In this process, the relay UE establishes an RRC connection with the gNB. The relay UE also establishes a CM connection with the AMF. The paging contains information indicating that it is a paging to a remote UE, allowing the relay UE to recognize that it is a paging to a remote UE. Having recognized that it is a paging to a remote UE, the relay UE can establish a PDU session for relaying.

[0221] In step ST1426, the UPF sends the pending data to the remote UE to the gNB connected to the relay UE, the gNB sends the data to the relay UE, and the relay UE can then send the data to the remote UE.

[0222] Furthermore, in step ST1425, the establishment of a PDU session between the relay UE and the UPF enables the transmission of data from the remote UE to the network (sometimes referred to as UL data).

[0223] In this way, it becomes possible to transition the relay UE to the RRC_Idle or CM_Idle state during communication between the remote UE and the network via the relay UE. Even when the relay UE is in the RRC_Idle or CM_Idle state, RRC and CM connections can be re-established as data is generated, and a PDU session for the relay can be established.

[0224] This document discloses what happens when data is generated from an AS or DN to a remote UE while the relay UE is in the RRC_Idle or CM_Idle state. Here, we disclose what happens when service data is generated from a remote UE.

[0225] The remote UE sends the generated data to the relay UE. When the relay UE receives data from the remote UE, it performs the process of establishing a PDU session with the network. In this way, even if the relay UE has transitioned to the RRC_Idle or CM_Idle state, if data is generated from the remote UE, a PDU session can be re-established between the relay UE and the network. This enables communication between the remote UE and the network using the PDU session. The relay UE that has received data from the remote UE may transition to a connected state with the network. The relay UE that has received data from the remote UE may transition to the RRC_Connected or CM_Connected state with the network. In this way, the state between the relay UE and the network becomes connected again, and communication between the remote UE and the network becomes possible via the relay UE.

[0226] Another method is disclosed. The remote UE notifies the relay UE of a PDU session establishment request. The PDU session may be a PDU session for relaying. The PDU session establishment request may include reason information. The reason information indicates the reason for requesting the establishment of the PDU session. The reason information may be, for example, data generation or a relay processing request. By providing reason information and including it in the PDU session establishment request, the relay UE can understand why the PDU session is being requested. When the relay UE receives the PDU session establishment request from the remote UE, it performs the PDU session establishment process with the network. After the PDU session is established, the relay UE may notify the remote UE that the PDU session establishment is complete. The remote UE sends data to the relay UE.

[0227] The relay UE may transition to a connected state with the NW upon the establishment of a PDU session. The relay UE may also transition to the RRC_Connected or CM_Connected state with the NW. In this way, the state between the relay UE and the NW becomes connected again, and communication between the remote UE and the NW becomes possible via the relay UE.

[0228] A remote UE may notify a relay UE of an RRC connection request. Alternatively, a remote UE may notify a relay UE of a CM connection request. Reason information may be included in the RRC connection request or CM connection request. The reason information indicates the reason for requesting the RRC connection or CM connection. The reason information may be, for example, data generation or a relay processing request. By providing and including reason information in the request, the relay UE can understand why the RRC connection or CM connection is being requested. Upon receiving the request, the relay UE may transition to the RRC_Connected or CM_Connected state with the NW. In this way, the state between the relay UE and the NW becomes connected again, and communication between the remote UE and the NW becomes possible via the relay UE. Furthermore, the remote UE may notify the relay UE of a PDU session establishment request. By establishing a PDU session with the NW, the relay UE can communicate data from the remote UE to the NW.

[0229] The relay UE may notify the remote UE whether a PDU session has been established with the NW. The relay UE may notify the remote UE whether it is in the RRC_Idle state with the NW. The relay UE may notify the remote UE whether it is in the CM_Idle state with the NW. RRC state information or CM state information may be provided. The relay UE may notify the remote UE of the RRC state information and / or CM state information with the NW. PC5-S signaling or RRC signaling may be used to notify this information. PSCCH or PSSCH may also be used to notify this information. Notification can be made earlier. In this way, the remote UE can recognize the connection status between the relay UE and the NW.

[0230] When service data is generated at a remote UE, the remote UE should decide whether or not to notify the aforementioned PDU session establishment request, RRC connection request, or CM connection request, depending on the connection status between the relay UE and the network.

[0231] If the connection between the relay UE and the network is released, or if the PDU session established between the relay UE and the network is released, the relay UE may notify the remote UE of the release of the connection between the relay UE and the network, or the release of the PDU session between the relay UE and the network. For example, if the connection between the relay UE and the network is released due to a deterioration in communication quality between the relay UE and the gNB, the relay UE will notify the remote UE of the release of the connection between the relay UE and the network. Upon receiving this information, the remote UE may make changes to the relay UE.

[0232] PC5-S signaling or RRC signaling may be used to notify the information. Alternatively, PSCCH or PSSCH may be used to notify the information. This allows for early notification. In this way, for example, a remote UE can make changes to the relay UE capable of relaying with the NW at an early stage.

[0233] This document discloses the case where a relay UE moves across the tracking area. The relay UE should perform a Tracking Area Update (TAU) operation with the network. The relay UE notifies the AMF of its own relevant information and the relevant information of the connected remote UE. The relay UE may notify this information during the TAU operation or after the TAU operation. The AMF, upon receiving the relevant information of the relay UE and the remote UE, creates association information. The AMF may appropriately apply the above method as its processing. In this way, even if the relay UE moves across the tracking area, the network can send data to the remote UE when data is generated for the remote UE.

[0234] In situations where a relay UE moves across a tracking area, the connection with the remote UE may not be maintained. In such cases, the relay UE does not need to notify the AMF of the relevant information about the remote UE whose connection is not maintained. Alternatively, the relay UE may notify the AMF of the release or discarding of the relevant information about the remote UE. Furthermore, the relay UE does not need to establish a PDU session used for relay communication with the remote UE. By doing so, when the connection between the relay UE and the remote UE is not maintained, it becomes possible to avoid establishing a PDU session and maintaining association information with the remote UE in the AMF. This avoids unnecessary processing, resulting in reduced malfunctions and lower power consumption for the system.

[0235] This document discloses how a remote UE can modify a relay UE. The remote UE performs a discovery process to find a relay UE that has a PDU session for relaying. The relay UE may transmit information during the discovery process indicating whether or not it has a PDU session for relaying. For example, the relay UE may include this information in a solicitation message and transmit it. In this way, the remote UE can find a relay UE that has a PDU session for relaying during the discovery process.

[0236] The remote UE measures the received quality (which may also be received power) from one or more relay UEs, including the connected relay UE, and selects the relay UE with the best communication quality. If the selected relay UE is different from the connected relay UE (sometimes referred to as the S-relay UE), the PC5-S link with the S-relay UE is released, and a PC5-S link is established with the selected relay UE (sometimes referred to as the T-relay UE).

[0237] When a remote UE releases the PC5-S link with an S-relay UE, the remote UE may perform the release process without notifying the S-relay UE. The S-relay UE may measure the time elapsed since the last communication with the remote UE. The S-relay UE may release the PC5-S link with the remote UE if the time elapsed since the last communication with the remote UE exceeds a predetermined period. This predetermined period may be managed by a timer.

[0238] The S-relay UE may release the PC5-S link if there is no data for a predetermined number of consecutive times on a resource periodically selected and reserved by the remote UE.

[0239] As part of the PC5-S link release process, the resources used for the PC5-S link connection may be released. connection You may perform a release process. You may also release the resources used for the RRC connection.

[0240] When a PC5-S link is established between the remote UE and the T-relay UE, the T-relay UE performs the process of establishing a PDU session for relaying with the network. The method described above can be applied as appropriate for this purpose.

[0241] In this way, the T-relay UE and the remote UE are associated. This enables data communication between the remote UE and the network via the T-relay UE. If there is no data between the remote UE and the network, the PDU session may be released. The connection between the T-relay UE and the network may also be released. The method described above may be applied as appropriate to achieve this.

[0242] This approach allows communication between the remote UE and the network via the modified relay UE, even if the remote UE changes the relay UE.

[0243] By using the method described in this disclosure, the relay UE can be transitioned to the CM_Idle or RRC_Idle state during communication between the remote UE and the network via the relay UE. Since the relay UE can receive data during the paging DRX cycle, it becomes possible to reduce the power consumption of the relay UE.

[0244] As previously disclosed, a PDU session is established between the relay UE and the CN for communication between the remote UE and the NW. A single PDU session may be established for relaying communication between multiple remote UEs and the NW. In other words, the relay UE may relay communication between multiple remote UEs and the NW using a single PDU session established with the CN. In this way, multiple remote UEs can communicate with the NW via a single relay UE.

[0245] New communication between the remote UE and the network may be performed using the PDU session initially established for communication between the remote UE and the network. In this case, the PDU session may be modified. For example, if the PDU session initially established for relaying is not suitable for the service to be performed between the new remote UE and the network, the PDU session may be modified. The relay UE may request modification of the PDU session. The remote UE may notify the relay UE of information regarding the service to be communicated with the network. The relay UE may use the service information obtained from the remote UE to decide whether or not to modify the PDU session.

[0246] A CN node, such as an AMF, SMF, or UPF, may request a modification of the PDU session. A remote UE may notify the CN node via a relay UE or gNB of information about services that communicate with the NW. The CN node may use the service information obtained from the remote UE to decide whether or not to modify the PDU session.

[0247] A PDU session for relaying should be configured for each relay UE. Alternatively, a PDU session for relaying may be managed for each relay UE. A PDU session for relaying may be managed using the relay UE identifier. The relay UE identifier may be used as the identifier for the UE where the PDU session for relaying is configured. The relay UE identifier may also be included in the configuration information for the PDU session for relaying.

[0248] In a situation where multiple remote UEs are communicating with the network using a single PDU session, the PDU session may be modified even if communication between one remote UE and the network terminates. The method described above should be applied as appropriate. The decision of whether or not to modify the PDU session should be made using information about the service that terminated communication between one remote UE and the network.

[0249] The PDU session release process described above is performed for each individual PDU session. In communication between multiple remote UEs and the network using a single relay PDU session, the release process described above should be performed when communication between all remote UEs and the network is temporarily interrupted. For example, the release process should be performed during a period when no communication is taking place between any remote UEs and the network. These methods should be applied as appropriate to the previously described methods.

[0250] Another method is disclosed. Multiple PDU sessions may be established for relaying communication between multiple remote UEs and the network. In other words, a relay UE may relay communication between multiple remote UEs and the network using multiple relay PDU sessions established with the CN. For example, one PDU session may be established for communication between each remote UE and the network. In this way, multiple remote UEs can communicate with the network through a single relay UE.

[0251] To initially establish communication between a single remote UE and the NW, a single PDU session is established between the relay UE and the CN. For communication between a new remote UE and the NW, in addition to the previously established PDU session between the relay UE and the CN, a new PDU session is established. A PDU session suitable for the service implemented between the new remote UE and the NW is established.

[0252] After a PC5-S link is established between a new remote UE and the relay UE, a new PDU session for relay communication between the remote UE and the NW may be established between the relay UE and the CN. It becomes possible to establish a PDU session suitable for communication between the remote UE and the NW.

[0253] Before a PC5-S link is established between a new remote UE and the relay UE, a new PDU session for relay communication between the new remote UE and the NW may be established between the relay UE and the CN. When the new remote UE communicates with the NW via the relay UE, the already established PDU session may be used, and it becomes possible to start the communication via the relay UE between the remote UE and the NW earlier.

[0254] A plurality of PDU sessions will be established for a single relay UE. Each PDU session may be set for each remote UE. Each PDU session may be managed for each remote UE. Each PDU session may be managed by the identifier of the remote UE. The identifier of the remote UE may be used as the identifier of the UE for which each PDU session is set. The identifier of the remote UE may be included in the setting information of the PDU session. Each PDU session may be managed not only by the identifier of the remote UE but also by the identifier of the relay UE and the identifier of the remote UE. For example, in addition to the identifier of the relay UE, the identifier of the remote UE may be set in the setting information of the PDU session. By doing so, it becomes possible to identify the PDU session for each remote UE.

[0255] In a situation where multiple remote UEs are communicating with the network using multiple PDU sessions, the PDU session for one remote UE may be released even if communication between that remote UE and the network terminates. The PDU session release process described above may be performed for each PDU session of each remote UE.

[0256] In communication between multiple remote UEs and the network using multiple relay PDU sessions, the aforementioned RRC connection release process and CM connection release process may be performed if communication between all remote UEs and the network is temporarily interrupted. For example, it is advisable to perform the aforementioned RRC connection release process and CM connection release process during periods when no communication is taking place between all remote UEs and the network. These methods should be applied as appropriate to the previously described methods.

[0257] Other methods are disclosed. The method described above for establishing one PDU session for relaying communication between multiple remote UEs and the network may be combined with the method for establishing multiple PDU sessions for relaying communication between multiple remote UEs and the network. One or more PDU sessions may be established for relaying communication between one or more remote UEs and the network. For example, one PDU session may be established for a group of multiple remote UEs for relaying communication between remote UEs within the group and the network. For example, one PDU session may be established for one or more remote UEs using the same service. In this way, the establishment of PDU sessions can be flexibly implemented according to the service being communicated between the remote UE and the network.

[0258] Modification 1 of Embodiment 1. This invention discloses another method for solving the problems described in Embodiment 1.

[0259] A UE determines the Preferred RRC State (RRC_Idle), RRC_Inactive, and RRC_Connected. A UE may also specify the RRC State it requests from other UEs. The UE then notifies the gNB of the RRC State it requests from other UEs. The gNB may then use the received RRC State information to change the RRC State of the other UE.

[0260] The remote UE determines the RRC state to request from the relay UE. The remote UE notifies the gNB of the RRC state to be requested from the relay UE. The remote UE notifies the gNB connected to the relay UE or the camped-on gNB of the RRC state to be requested from the relay UE via the relay UE. Since the gNB connected to the relay UE or the camped-on gNB can change the RRC state of the relay UE, it is preferable for the remote UE to notify the gNB connected to the relay UE or the camped-on gNB of the RRC state to be requested from the relay UE.

[0261] For example, if there is no communication data between the remote UE and the NW, the remote UE decides to set the RRC state it requests from the relay UE to RRC_Idle. The remote UE sets the RRC state information it requests from the relay UE to RRC_Idle and notifies the gNB connected to the relay UE of the RRC state information it requests from the relay UE via the relay UE. The gNB connected to the relay UE may use the received RRC state information it requests from the relay UE to change the RRC state of the relay UE. For example, if the relay UE is in the RRC connection state, the gNB may perform an RRC connection release process to change the relay UE to the RRC_Idle state.

[0262] The requested RRC status information may include information to identify which UE the request is for. Alternatively, information to identify which UE the request is for may be notified along with the requested RRC status information. In this way, the node that receives the requested RRC status information can recognize which UE the request is for.

[0263] The requested RRC status information may include information to identify which UE made the request. Alternatively, information to identify which UE made the request may be notified along with the requested RRC status information. In this way, the node that receives the requested RRC status information can recognize which UE made the request.

[0264] The remote UE may notify the relay UE of the desired RRC status information using PC5-S signaling. Even if RRC settings for data transmission are not configured on the PC5 link, the remote UE and the relay UE can notify each other of the desired RRC status information. This allows for early notification of the desired RRC status information. Alternatively, the remote UE may notify the relay UE of the desired RRC status information using PC5's RRC signaling. This allows the relay UE to process the information using RRC. As described later, when the relay UE notifies the gNB of the desired RRC status information using RRC signaling, processing can be unified within RRC. This avoids complexity and reduces malfunctions.

[0265] If a relay UE is in the RRC_Connected state, the relay UE may notify the gNB connected to it of the requested RRC status information received from the remote UE via RRC signaling. For example, as mentioned above, this avoids complicating the process when the relay UE notifies the requested RRC status information received from the remote UE using the RRC signaling of PC5 between the remote UE and the relay UE. Alternatively, the requested RRC status information may be included in UE Assistance Information and notified via RRC signaling.

[0266] If the relay UE is in the RRC_Idle or RRC_Inactive state, the relay UE may notify the camp-on gNB of the desired RRC state information received from the remote UE using RA (Random Access) processing. For example, in the case of 4-step RACH (see Non-Patent Literature 16 (TS38.300)), the relay UE may notify the desired RRC state information using MSG3. In the case of MSG3, collision avoidance processing can be used to improve the probability of arrival. The relay UE may also notify the desired RRC state information using, for example, 2-step RACH processing. In the case of 2-step RACH (see Non-Patent Literature 16 (TS38.300)), the relay UE may notify the desired RRC state information using MSGA. The relay UE may also notify the desired RRC state information using PUSCH in MSGA. This allows for earlier notification.

[0267] If the relay UE is in the RRC_Idle or RRC_Inactive state, the relay UE may establish an RRC connection with the gNB and then notify the gNB of the desired RRC status information received from the remote UE. The method described above for when the relay UE is in the RRC_Connected state may be applied as appropriate for this notification.

[0268] In this way, the remote UE can notify the gNB to which it is connected of the RRC status information it has decided to request from the relay UE. The gNB can then recognize the requested RRC status, which UE is making the request, and which UE the request is directed to, from the received requested RRC status information. The gNB may then use the received requested RRC status information to change or maintain the RRC status of the relay UE.

[0269] For example, if a relay UE is in an RRC connection state and the remote UE determines that there is no more communication data with the network, the remote UE sets the desired RRC state information to RRC_Idle and notifies the relay UE of this setting. The remote UE may include in this notification information indicating what the remote UE is requesting and what it is requesting from the relay UE. The relay UE notifies the connected gNB of this information. Upon receiving this information, the gNB may use this information to decide to transition the relay UE to the RRC_Idle state. The gNB then performs the RRC connection release process with the relay UE.

[0270] The gNB may notify the AMF of a request to release the PDU session between the relay UE and the NW. Upon receiving this request, the AMF may perform the PDU session release process between the relay UE and the NW. The AMF may also perform the CM connection release process with the relay UE. A relay UE that has transitioned to the RRC_Idle or CM_Idle state receives paging from the gNB at the paging DRX period. The methods described above may be applied as appropriate. Even after a relay UE has transitioned to the RRC_Idle or CM_Idle state, it is still possible to send data to a remote UE if data is generated for the remote UE.

[0271] The gNB may make a decision different from the request for the RRC status of the relay UE. The gNB may notify the remote UE of the RRC status of the relay UE as determined by the gNB. The remote UE will then be able to see what the status of the relay UE will be. For example, the remote UE will be able to decide whether to make another request. For example, the remote UE will be able to decide whether to change the relay UE.

[0272] If the gNB makes a decision that differs from the RRC status request to the relay UE, it may notify the remote UE of a rejection message. The gNB may include reason information in the rejection message. The remote UE can then understand why the request was rejected. The gNB may also include the RRC status determined by the gNB in ​​the rejection message. The remote UE can then understand what will happen to the relay UE's status. For example, the remote UE can decide whether to make the request again. For example, the remote UE can decide whether to change the relay UE.

[0273] Figures 17 to 19 are sequence diagrams showing an example of a method for communication between a UE and a NW via a relay UE, according to a modification 1 of Embodiment 1. Figures 17 to 19 are connected at the boundary lines BL1718 and BL1819. Figures 17 to 19 disclose a method for transitioning the relay UE to the RRC_Idle or CM_Idle state when there is no data between the remote UE and the NW, by notifying the gNB connected to the relay UE of the RRC state information it requests. In Figures 17 to 19, steps common to Figures 14 to 16 are given the same step numbers, and common explanations are omitted.

[0274] In steps ST1409 and ST1410, the remote UE performs data transmission and reception with the NW. The remote UE determines whether data is generated in the communication between the remote UE and the NW. For example, if the remote UE recognizes from the service-related information that no data has been generated for a predetermined period, it may determine that no data is generated. The remote UE that determines that no data is generated sets the RRC status information requested for the relay UE to RRC_Idle. In step ST1501, the remote UE notifies the gNB to which the relay UE is connected via the relay UE of the RRC status information requested for the UE. The remote UE may include in the RRC status information information indicating which UE the request is from and which UE it is for.

[0275] The gNB that receives the RRC status information can recognize that the RRC status request for the relay UE is RRC_Idle. Also, since it is a request from the remote UE, the gNB can recognize that it is a request for relay communication. In step ST1502, the gNB determines whether to transition or maintain the RRC status of the relay UE using the RRC status information requested for the relay UE. Here, the gNB determines to transition the relay UE to RRC_Idle.

[0276] In step ST1503, the gNB notifies the AMF of a request to release the relay PDU session between the relay UE and the NW. In step ST1414, the AMF performs PDU session release processing between the relay UE and the NW. The steps after ST1414 are common to FIGS. 14 to 16, so the description is omitted.

[0277] By doing so, the remote UE can notify the gNB to which the relay UE is connected of the RRC status requested for the relay UE. The gNB can recognize the request, and it becomes possible to transition or maintain the relay UE to the RRC status requested by the remote UE.

[0278] A remote UE may notify the relay UE of the RRC status information it requests. For example, if multiple remote UEs are connected to a relay UE, the multiple remote UEs will notify the relay UE of the RRC status information they request. The relay UE may use the RRC status information it receives from one or more remote UEs to derive the RRC status information it requests.

[0279] For example, if a relay UE receives RRC status information from one or more remote UEs and all of them are RRC_Idle, the relay UE will set its own RRC status information to RRC_Idle. For example, if a relay UE receives RRC status information from one or more remote UEs and any one of them is RRC_Connected, the relay UE will set its own RRC status information to RRC_Connected.

[0280] The relay UE notifies the gNB to which it is connected or camped on of the gNB that it has derived the RRC state information requested for its own UE. The gNB that receives this information may use it to decide whether to transition or maintain the relay UE's RRC state. For example, if the gNB receives from the relay UE that the requested RRC state information for the relay UE is RRC_Idle, and the relay UE is in an RRC connection state, the gNB may perform an RRC connection release process to transition to the RRC_Idle state.

[0281] The method described above should be applied as a method for notifying a relay UE of RRC status information requested from other UEs. The method described above should be applied as appropriate as a method for notifying a gNB of RRC status information requested from the relay UE.

[0282] In this way, for example, when a relay UE is connected to multiple remote UEs, the relay UE can set the RRC state requested by its own UE and notify the gNB of the requested RRC state. The gNB can then use the received information to transition or maintain the relay UE's RRC state. Therefore, the RRC state of the relay UE can be controlled according to the data communication status of the multiple remote UEs connected to the relay UE.

[0283] A remote UE may notify the AMF of the RRC status information it requests from other UEs. A remote UE may also notify the AMF of the RRC status information it requests from the relay UE via a relay UE and a gNB. A relay UE may also notify the AMF of the RRC status information it requests from itself. Upon receiving this information, the AMF may use it to decide whether to release or maintain the PDU session between the relay UE and the NW. For example, if the AMF receives from the remote UE via a gNB that the RRC status information it requests from the relay UE is RRC_Idle, the AMF may release the PDU session between the relay UE and the NW. Upon the release of the PDU session, the gNB may perform an RRC connection release process with the relay UE. The AMF may also perform a CM connection release process. In this way, the relay UE can be transitioned to the RRC_Idle or CM_Idle state. A relay UE that has transitioned to the RRC_Idle or CM_Idle state receives paging from the gNB at the paging DRX period.

[0284] Requested CM status information may be provided. Requested CM statuses include CM_Idle and CM_Connected. A UE may provide its own requested CM status information. Other UEs may also provide requested CM status information. A UE may notify the AMF of the requested CM status information. A UE may notify the AMF of the requested CM status information using NAS signaling. The UE may notify the gNB of this information using RRC signaling, and the gNB may notify the AMF of this information using N2 signaling. A UE may notify UEs connected via PC5 of the requested CM status information. A UE may use PC5-S signaling or PC5's RRC signaling. The AMF receives the requested CM status information. but The system determines which UE the requested CM status information belongs to, and then uses the CM status information of that UE to decide whether to transition or maintain the CM status of that UE.

[0285] For example, if a remote UE determines that there is no more communication data with the network, it sets the requested CM status information to CM_Idle for the relay UE and notifies the AMF of this setting via the relay UE and gNB. If the relay UE is in a CM connection state, the AMF uses the received CM status information to determine whether to transition the relay UE to CM_Idle and performs a CM connection release process. In conjunction with the release of the CM connection between the relay UE and the network, the gNB performs an RRC connection release process with the relay UE. In this way, it is possible to transition the relay UE to the CM_Idle or RRC_Idle state.

[0286] The AMF may make a decision different from the request for the CM status of the relay UE. The AMF may notify the remote UE of the CM status of the relay UE as determined by the AMF. The remote UE will then be able to recognize what the status of the relay UE will be. For example, the remote UE will be able to decide whether to make another request. For example, the remote UE will be able to decide whether to change the relay UE.

[0287] If the AMF determines that its CM status differs from the request for the relay UE, it may notify the remote UE of a rejection message. The AMF may include reason information in the rejection message. The remote UE can then understand why the request was rejected. The AMF may also include the CM status determined by the gNB in ​​the rejection message. The remote UE can then understand what will happen to the relay UE's status. For example, the remote UE can decide whether to make the request again. For example, the remote UE can decide whether to change the relay UE.

[0288] A remote UE may notify the relay UE of the CM status information it requests. For example, if multiple remote UEs are connected to a relay UE, the multiple remote UEs will notify the relay UE of the CM status information they request. The relay UE may use the CM status information it receives from one or more remote UEs to derive the CM status information it requests.

[0289] For example, if a relay UE receives CM status information from one or more remote UEs and all of them are CM_Idle, the relay UE will set the requested CM status information to CM_Idle. For example, if a relay UE receives CM status information from one or more remote UEs and any one of them is CM_Connected, the relay UE will set the requested CM status information to CM_Connected.

[0290] The relay UE notifies the gNB to which it is connected or the gNB to which it is camped on of the CM state information it has derived that is requested of its own UE. The gNB that receives this information may use it to decide whether to transition or maintain the relay UE's CM state. For example, if the gNB receives from the relay UE that the requested CM state information is CM_Idle, and the relay UE is in a CM connection state, the gNB may request the AMF to release the CM connection in order to transition to the CM_Idle state.

[0291] The relay UE may notify the AMF of the CM state information it has derived that is requested for its own UE. The relay UE may notify the AMF via the gNB to which its own UE is connected or via a gNB that it has camped on. Upon receiving this information, the AMF may use this information to decide whether to transition or maintain the relay UE's CM state. For example, if the AMF receives from the relay UE that the requested CM state information for the relay UE is CM_Idle, and the relay UE is in a CM connection state, the AMF may perform a CM connection release process to transition to the CM_Idle state.

[0292] As a method for notifying a relay UE of requested CM status information from a remote UE, it is advisable to appropriately apply the aforementioned method for notifying requested RRC status information.

[0293] In this way, for example, when a relay UE is connected to multiple remote UEs, the relay UE can set the CM state requested by its own UE and notify the gNB or AMF of the requested CM state. The gNB or AMF can then use the received information to transition or maintain the relay UE's CM state. Therefore, the relay UE's CM state can be controlled according to the data communication status of the multiple remote UEs connected to the relay UE.

[0294] By using the method described in this disclosure, in communication between a remote UE and a network via a relay UE, the relay UE can be transitioned to the CM_Idle or RRC_Idle state depending on whether or not there is data for the remote UE to communicate with the network. Since the relay UE can receive data at the paging DRX cycle, it becomes possible to reduce the power consumption of the relay UE.

[0295] Modification 2 of Embodiment 1. This invention discloses another method for solving the problems described in Embodiment 1.

[0296] Embodiment 1 discloses a method for transitioning a relay UE to the CM_Idle or RRC_Idle state in communication between a remote UE and a network via a relay UE. A relay UE that has transitioned to the CM_Idle or RRC_Idle state receives paging from the gNB at the paging DRX period. The paging method is CN start paging (CN shi There are two types: RAN-initiated paging and RAN-initiated paging.

[0297] One method for CN start paging is to use a paging DRX period (sometimes referred to as the cell-specific paging DRX period) announced by the cell. In this method, the cell sets the paging DRX period. The gNB may also set the paging DRX period for the cells it comprises. The cell's paging DRX period is set individually for each cell. Therefore, in communication between a remote UE and the NW via a relay UE, it is not possible to set a cell-specific paging DRX period suitable for the relay UE.

[0298] One method for CN start paging is to use a DRX period specific to the UE (User Interface Device). This method allows setting a DRX period for each UE. Therefore, in communication between a remote UE and the network via a relay UE, a DRX period can be set for each relay UE. However, in communication between a remote UE and the network via a relay UE, the remote UE generates the communication data, while the relay UE does not. Therefore, it is not possible to set a DRX interval suitable for the services occurring between the remote UE and the network. A method to solve this problem is disclosed.

[0299] A UE will provide DRX-related information from other UEs as requested by the UE. This information will be referred to in this disclosure as DRX-related information requested from other UEs. The UE will determine the DRX-related information to request from other UEs. Specific examples of requested DRX-related information include the paging DRX period, paging frames, paging slots, etc.

[0300] Other specific examples of the requested DRX-related information include the paging reception period and the period of the paging reception period. The paging reception period and the period of the paging reception period may be integer multiples of the DRX period for paging for each cell. These integer values ​​may be used as information for the paging reception period and the period of paging reception period. As a method of DRX processing for paging using this information, for example, the UE may receive the paging reception period and paging, and then receive the next paging reception period and paging after the period of the paging reception period has elapsed from the start of the paging reception period.

[0301] The aforementioned specific examples can be combined as requested DRX-related information.

[0302] The UE notifies the AMF of the DRX-related information it requests from other UEs. The AMF uses the received DRX-related information to derive the DRX settings for paging for the other UE. Individual DRX settings for each UE may also be used as the DRX settings for paging. Specific examples of DRX settings for paging include the DRX period, paging frames, and paging slots.

[0303] Other specific examples of DRX settings for paging include the paging reception period and the period of the paging reception period. The paging reception period and the period of the paging reception period may be integer multiples of the DRX period for paging for each cell. These integer values ​​may be used as information for the paging reception period and the period of the paging reception period.

[0304] The aforementioned specific examples can be combined to create a DRX configuration for paging.

[0305] The requested DRX-related information may include information to identify which UE the request is for. Alternatively, information to identify which UE the request is for may be notified along with the requested DRX-related information. In this way, the node receiving the requested DRX-related information can recognize which UE the request is for.

[0306] The requested DRX-related information may include information to identify which UE made the request. Alternatively, information to identify which UE made the request may be notified along with the requested DRX-related information. In this way, the node receiving the requested DRX-related information can recognize which UE made the request.

[0307] The requested DRX-related information may include information about the service. Information about the service may also be provided along with the requested DRX-related information. For example, an identifier to identify the service, the service's QoS, etc., may be provided. This allows the node receiving the requested DRX-related information to recognize what service the requested DRX corresponds to.

[0308] The AMF notifies other UEs of the derived DRX settings for paging. The AMF may also notify the other UEs of the derived settings via the gNB to which they are connected. The other UEs receive paging using the received individual DRX settings for paging. In this way, it becomes possible to notify UEs other than the UE that requested the DRX-related information of their individual DRX settings for paging according to the requested DRX-related information. The UEs can receive paging using the DRX settings for paging configured according to the DRX-related information requested by other UEs.

[0309] For example, in communication between a remote UE and a network via a relay UE, the remote UE determines the DRX-related information it requests from the relay UE. The remote UE notifies the AMF of the DRX-related information it requests from the relay UE. The remote UE notifies the AMF of the DRX-related information it requests from the relay UE via the relay UE and gNB. The AMF uses the received DRX-related information it requests from the relay UE to configure the paging DRX settings of the relay UE. These paging DRX settings may be individual paging DRX settings for each relay UE. These paging DRX settings may also be for relays.

[0310] Notification of DRX-related information requested from the relay UE to the AMF from the remote UE may be performed when the remote UE generates DRX-related information to be requested from the relay UE. Alternatively, the remote UE may include the DRX-related information requested from the relay UE in the remote UE-related information notified to the AMF and notify the AMF. Alternatively, the DRX-related information requested from the relay UE may be notified during the remote UE's registration process or service request process. The remote UE's registration process and service request process may be performed to the AMF via the relay UE and the gNB connected to the relay UE. If the remote UE is aware of the DRX-related information to be requested from the relay UE in advance, notification can be made earlier.

[0311] As a method for notifying the relay UE of the DRX-related information requested from the remote UE, the method for notifying the relay UE of the requested RRC status information, disclosed in Modification 1 of Embodiment 1, can be appropriately applied. Similar effects can be obtained.

[0312] The relay UE may notify the AMF of the DRX-related information it requests via NAS signaling. Alternatively, RRC signaling may be used for notification from the relay UE to the gNB, and N2 signaling may be used for notification from the gNB to the AMF. Furthermore, as a method for notifying the gNB of the DRX-related information it requests from the relay UE, the method disclosed in Modification 1 of Embodiment 1, for notifying the gNB of the requested RRC status information from the relay UE may be appropriately applied. Similar effects can be obtained.

[0313] The AMF notifies the relay UE of the derived DRX settings for paging specific to that relay UE. The AMF may also notify the relay UE of the derived settings via the gNB to which the relay UE is connected. The relay UE receives paging using the received DRX settings for paging specific to that relay UE.

[0314] Notification of individual DRX settings for paging from the AMF to the relay UE may occur after the AMF has derived the settings. For example, the AMF may notify the relay UE of the settings during the PDU session establishment process between the relay UE and the NW. For example, the AMF may notify the relay UE of the settings during the RRC connection release process or the CM connection release process.

[0315] The AMF may notify the relay UEs of their individual paging DRX settings via NAS signaling. Alternatively, the AMF may use N2 signaling to notify the gNB, and the gNB may use RRC signaling to notify the relay UEs.

[0316] The AMF may configure paging DRX settings different from the DRX-related information requested from the relay UE. The AMF may not configure paging DRX settings for individual UEs. The AMF may notify the remote UE of the paging DRX settings configured on the relay UE. The remote UE can recognize the paging DRX settings configured on the relay UE. The AMF may include reason information in the notification. If the AMF configures paging DRX settings different from the DRX-related information requested from the relay UE, the remote UE can recognize the reason. This allows the remote UE to decide, for example, whether to make another request.

[0317] The remote UE may notify the AMF of a request to reset the DRX-related information requested from the relay UE. The remote UE may also notify the AMF that it does not request DRX settings from the relay UE. The AMF can then recognize that the remote UE has not requested DRX settings from the relay UE. The AMF may use this notification to decide whether to remove the UE-specific DRX settings for paging from the relay UE. The AMF may also notify the relay UE that it has removed the UE-specific DRX settings for paging from the relay UE. In this way, the relay UE does not have to perform paging reception processing using the UE-specific DRX settings for paging. The AMF may also notify the remote UE that the relay UE has removed the UE-specific DRX settings for paging from the relay UE. In this way, the remote UE can recognize whether or not the relay UE is performing paging reception processing using the UE-specific DRX settings for paging from the relay UE.

[0318] In this way, the relay UE can be notified of the DRX settings for paging specific to each UE, based on the DRX-related information requested by the remote UE. The relay UE can then receive paging using the DRX settings configured according to the DRX-related information requested by the remote UE.

[0319] Even if a relay UE is connected to one or more remote UEs, the method described above should be applied to each remote UE. Each of the one or more remote UEs determines the DRX-related information it requests from the relay UE. Each remote UE notifies the AMF of the DRX-related information it requests from the relay UE. The AMF uses the DRX-related information received from each remote UE to configure one or more paging DRX settings for the relay UE. The AMF may configure the paging DRX settings for the relay UE for each remote UE. These one or more paging DRX settings may be individual paging DRX settings for each relay UE. These paging DRX settings may also be for relays.

[0320] The AMF notifies the relay UE of the derived DRX settings for paging for one or more individual relay UEs. The relay UE receives paging using the received DRX settings for one or more individual relay UEs. In this way, even when multiple remote UEs are connected to the relay UE, the relay UE can receive paging at a DRX cycle corresponding to the DRX cycle requested by each remote UE.

[0321] A remote UE may notify the relay UE of the DRX-related information it requests. For example, if multiple remote UEs are connected to a relay UE, the multiple remote UEs will notify the relay UE of the DRX-related information they request. The relay UE may use the DRX-related information it receives from one or more remote UEs to derive the DRX-related information it requests.

[0322] For example, a relay UE selects the shortest DRX period from the DRX-related information requested by one or more remote UEs, and sets the selected DRX period in the DRX-related information requested by its own UE.

[0323] The relay UE notifies the AMF of the DRX-related information it has derived and requested for its own UE. The relay UE may also notify the AMF of this information via a gNB. The AMF uses the received DRX-related information requested for the relay UE to configure the DRX settings for paging on the relay UE. These paging DRX settings may be individual settings for each relay UE. These paging DRX settings may also be for relays. The AMF notifies the relay UE of the individual paging DRX settings it has derived. The AMF may also notify the relay UE of the derived settings via a gNB to which the relay UE is connected. The relay UE uses the received individual paging DRX settings to receive paging.

[0324] In this way, even when data is generated at a remote UE for one or more relay UEs connected to it, the delay caused by the DRX cycle for paging to the relay UE can be reduced.

[0325] The aforementioned methods should be applied as appropriate to notify the relay UE of DRX-related information requested from other UEs, the relay UE of RRC status information requested from its own relay UE to the AMF, and the AMF of the DRX settings for paging to the relay UE.

[0326] Figures 20 to 22 are sequence diagrams showing an example of a method for communication between a UE and a NW via a relay UE, according to a modified example 2 of Embodiment 1. Figures 20 to 22 are connected at the boundary lines BL2021 and BL2122. Figures 20 to 22 disclose an example in which, when there is no data between the remote UE and the NW, the remote UE notifies the gNB connected to the relay UE of the DRX-related information it requests from the relay UE. According to this example, the relay UE can receive paging at the DRX cycle for paging desired by the remote UE. In Figures 20 to 22, steps common to Figures 14 to 16 are given the same step numbers, and common explanations are omitted.

[0327] In step ST1405, the remote UE notifies the AMF of remote UE-related information, enabling communication between the remote UE and the network. In step ST1601, the remote UE notifies the AMF of DRX-related information requested from the relay UE. The remote UE notifies the AMF of DRX-related information requested from the relay UE via the relay UE and gNB. The remote UE sets the DRX-related information requested from the relay UE. For example, the remote UE may derive the data generation cycle from the service-related information and use that information to set the DRX-related information requested from the relay UE, such as the paging DRX cycle. The remote UE may also include information indicating which UE is making the request to which UE in the DRX-related information. The remote UE may notify the DRX-related information together with the remote UE-related information notified from the remote UE to the AMF in step ST1405, or include it in the remote UE-related information in step ST1405. This allows for early processing by the gNB.

[0328] Upon receiving the DRX-related information, the AMF becomes able to recognize the paging DRX setting for the relay UE. Furthermore, the AMF recognizes that the request is for relay communication, as it originates from a remote UE. In step ST1602, the AMF uses the paging DRX-related information requested from the relay UE to derive the paging DRX setting for the relay UE. This paging DRX setting may be an individual DRX setting for each UE. Paging DRX settings can be configured for each relay UE.

[0329] In step ST1603, the AMF notifies the relay UE via the gNB of the paging DRX setting for the relay UE. The relay UE receives paging using this paging DRX setting when it transitions to RRC_Idle or CM_Idle. The relay UE may receive paging using both the paging DRX setting announced by the cell and the paging DRX setting received from the AMF. Alternatively, the relay UE may receive paging using the DRX setting with the shorter DRX period.

[0330] Data generation between the remote UE and the NW ceases, and in step ST1415, an RRC connection release process is performed between the relay UE and the gNB, and a CM connection release process is performed between the relay UE, gNB, and AMF. As a result, the relay UE transitions to the RRC_Idle or CM_Idle state. In step ST1604, the relay UE receives paging with the DRX setting received from the AMF.

[0331] In step ST1417, data is generated to the remote UE, and in step ST1421, the AMF receives a data generation notification from the SMF. Upon receiving the data generation notification, the AMF may, in step ST1605, postpone the notification of paging to the relay UE via the gNB until the paging DRX timing configured for the relay UE. This allows for paging to be notified at the appropriate time.

[0332] By using the method described herein, in communication between a remote UE and a network via a relay UE, it becomes possible to set a paging DRX for the relay UE according to the generation cycle of the data that the remote UE communicates with the network. Since the relay UE can receive data at a paging DRX cycle that is suitable for the generation cycle of the data that the remote UE communicates with the network, it becomes possible to reduce the power consumption of the relay UE.

[0333] Embodiment 2. This invention discloses another method for solving the problems described in Embodiment 1.

[0334] For relay UEs with UE-to-NW relay capabilities, transition to RRC_Inactive is permitted. The RRC connection between the relay UE and the gNB may be suspended. Relay UEs with UE-to-NW relay capabilities maintain the CM_Connected state. InactiveIn this state, the RRC is in a stopped state and the CM is in a connected state. The PDU session between the relay UE and the NW may be released. The above processing may also be performed even if a PC5-S link has been established between the remote UE and the relay UE.

[0335] The process for transitioning to RRC_Inactive is disclosed. RRC termination is performed between the gNB and the relay UE. The gNB may initiate RRC termination with the relay UE. For example, the gNB may notify the relay UE of an RRC release message with suspend information. This causes RRC termination to be performed between the gNB and the relay UE. The relay UE may request RRC termination from the gNB. Upon receiving the RRC termination request, the gNB performs RRC termination with the relay UE. Also, if the AMF performs PDU session release processing with the gNB, the gNB may perform RRC termination with the relay UE. The CM connection between the relay UE and the NW is maintained. The AMF may maintain the CM connection between the relay UE and the NW. The CM_Connected state of the relay UE may be maintained. By maintaining the CM connection, when the relay UE communicates with the NW again, a transition of the CM state is unnecessary, enabling low-latency communication.

[0336] For the release process of PDU sessions by the relay UE and network nodes, the method disclosed in Embodiment 1 may be applied as appropriate.

[0337] It is preferable to perform the transition process to RRC_Inactive described above while the PC5-S link between the relay UE and the remote UE is connected. Alternatively, it is preferable to perform the release process described above without releasing the PC5-S link between the relay UE and the remote UE.

[0338] For example, if communication between the remote UE and the network is temporarily interrupted, it is advisable to perform the aforementioned transition process to RRC_Inactive. Also, for example, if communication between the remote UE and the network occurs periodically, it is advisable to perform the aforementioned transition process to RRC_Inactive during periods when such communication is not occurring. Perform the aforementioned transition process to RRC_Inactive and set the relay UE to RRC_ Inactive By switching to this state, the power consumption of the relay UE can be reduced.

[0339] As a method for transitioning to RRC_Inactive in relay UEs and NW nodes, the method disclosed in Embodiment 1 may be appropriately applied. For example, as a method for determining whether to transition to RRC_Inactive, the method disclosed in Embodiment 1 for determining whether to perform or request release processing in relay UEs and NW nodes may be appropriately applied.

[0340] A remote UE may request a transition to RRC_Inactive between the relay UE and the gNB. A remote UE may request a transition to RRC_INactive from either the relay UE or the gNB.

[0341] To recognize services that communicate with the network, the remote UE can easily determine when communication between the remote UE and the network will temporarily cease. By requesting the aforementioned transition to RRC_Inactive between the relay UE and the network, the remote UE can perform the transition process to the RRC_Inactive state of the relay UE, which is suitable for the communication service between the remote UE and the network. In this way, for example, if there is no data communication on the PC5-S link for a predetermined period, the remote UE will prompt the relay UE to enter the RRC_Inactive state. Inactive This allows the system to transition to a different state, reducing the power consumption of the relay UE.

[0342] Relay UE is RRC_ InactiveIn this state, when a gNB receives data from a UPF to a remote UE via a relay UE, or receives signaling from an AMF to a relay UE, it notifies the relay UE associated with the remote UE of paging. This paging is called RAN paging. RAN paging is performed from one or more gNBs in a predetermined area to their subordinate UEs. This predetermined area is called an RNA (RAN Notification Area).

[0343] gNBs notify surrounding gNBs of RAN paging. Xn signaling may be used for this notification. gNBs contained in RNA transmit the received RAN paging to their subordinate UEs. In this way, gNBs within RNA can transmit RAN paging to their subordinate UEs.

[0344] RAN paging transmitted from a gNB to its subordinate UEs, and / or RAN paging notified from a gNB to surrounding gNBs, may include information indicating that the paging is due to data generation or signaling to a remote UE. Alternatively, paging to a relay UE may include information about the remote UE, such as its identifier. In this way, the relay UE receiving the RAN paging can recognize that the paging is due to data generation to a remote UE.

[0345] A relay UE that receives RAN paging transitions to RRC_Connected with the NW. The relay UE that receives RAN paging may notify the gNB of an RRC Resume Request. The gNB requests the serving gNB prior to the relay UE to notify it of the RAN UE context. The serving gNB prior to the relay UE notifies the gNB of the RAN UE context. The serving gNB prior to the relay UE may include association information between the relay UE and the remote UE in the RAN UE context. The serving gNB prior to the relay UE may include this association information in the relay UE's RAN UE context.

[0346] A RAN UE context may be provided for the remote UE. The association information may be included in the RAN UE context of the remote UE. The gNB may store the RAN UE context information of the remote UE. The gNB may store the association information separately from the RAN UE context information. The serving gNB before the relay UE may notify the gNB of the RAN UE context of the remote UE along with the RAN UE context of the relay UE. Alternatively, the serving gNB before the relay UE may notify the gNB of the association information along with the RAN UE context of the relay UE.

[0347] A gNB that receives an RRC Resume Request from a relay UE may request the serving gNB prior to the relay UE to notify it of the remote UE's RAN UE context. The serving gNB prior to the relay UE then notifies the requesting gNB of the remote UE's RAN UE context.

[0348] A gNB that receives an RRC Resume Request from a relay UE may request the serving gNB prior to the relay UE to notify it of the association information between the remote UE where the data or signaling originated and the relay UE. The serving gNB prior to the relay UE will then notify the requesting gNB of the association information between the remote UE and the relay UE.

[0349] In this way, the gNB newly connected to the relay UE can recognize the association between the remote UE and the relay UE. This reduces the likelihood of malfunctions when the gNB notifies the remote UE of data or signaling via the relay UE.

[0350] The gNB, having received association information between the remote UE and the relay UE from the serving gNB preceding the relay UE, notifies the relay UE of the RRC switchback. The relay UE transitions to the RRC_Connected state. The relay UE notifies the gNB that the transition to the RRC_Connected state is complete. Path switch processing is performed in the gNB, AMF, SMF, and UPF. In this way, when data is generated for the remote UE, the relay UE can transition to RRC_Connected.

[0351] A relay UE that receives RAN paging may establish a PDU session with the gNB it was connected to before transitioning to RRC_Inactive. If the relay UE that receives paging receives information indicating that the paging is due to data generation to a remote UE, it establishes a PDU session with the network. This PDU session may be for relay purposes. This PDU session may also be for communication with the remote UE that generated the data. In this way, a PDU session for communication between the remote UE and the network can be established between the relay UE and the network. Even after the relay UE has transitioned to the RRC_Inactive state, if data is generated to a remote UE, a PDU session can be established again between the relay UE and the network. This enables communication between the remote UE and the network using the PDU session.

[0352] By doing so, the relay UE can perform DRX at the DRX cycle used for paging in RAN paging, thus enabling lower power consumption for the relay UE.

[0353] When a relay UE is in the RRC_Inactive state and service data is generated from a remote UE, the processing described in Embodiment 1 for when a relay UE is in the RRC_Idle or CM_Idle state and service data is generated from a remote UE may be appropriately applied. For example, the transition process from RRC_Inactive to RRC_Connected and the PDU session establishment process may be performed. In this way, data can be communicated from the remote UE to the network.

[0354] The method disclosed in Modification 1 of Embodiment 1 may also be applied. In Modification 1 of Embodiment 1, a method is disclosed in which a remote UE determines the RRC state to request from the relay UE and notifies the gNB connected to the relay UE of the determined RRC state information. The RRC state to request from the relay UE is RRC_ InactiveYou may also configure this. The gNB connected to the relay UE may use the RRC status information it receives from the relay UE to change the RRC status of the relay UE. For example, if the relay UE is in the RRC connected state, it may perform an RRC stop process to change it to the RRC_Inactive state.

[0355] In this way, during communication between the remote UE and the network via the relay UE, the relay UE can be switched to the RRC_Inactive state depending on whether or not there is data for the remote UE to communicate with the network. Since the relay UE can receive data during the RAN paging DRX cycle, it becomes possible to reduce the power consumption of the relay UE.

[0356] For RAN paging, individual DRX settings may be configured for each UE. Specific examples of RAN paging DRX settings include paging DRX period, paging frame, paging slot, etc., and these may be combined. gNB may configure individual DRX settings for relay UEs for RAN paging. gNB may configure individual DRX settings for relay UEs if the relay UE is RRC_ Connected In this state, the relay UE may be notified of the settings for the individual DRX used by the RAN paging UE. For example, the gNB may notify the relay UE of the DRX settings by including them in the RRC stop signaling.

[0357] AMF may configure individual DRX for RAN paging UEs for relay UEs. AMF may configure RRC_ Connected In this state, the relay UE may be notified of the settings for the individual DRX of the RAN paging UE. For example, the AMF may notify the DRX settings via NAS signaling. Alternatively, N2 signaling may be used for notification from the AMF to the gNB, and RRC signaling may be used for notification from the gNB to the relay UE.

[0358] A gNB may notify neighboring gNBs of DRX-related information for RAN paging. The gNB may include this information in the RAN paging information, or notify it together with the RAN paging information. In this way, gNBs within RNA can send paging to the relay UE with the same RAN paging DRX settings.

[0359] In this way, by configuring individual DRX settings for RAN paging on each relay UE, it becomes possible to configure the relay UE with DRX settings suitable for the data communication interval between, for example, a remote UE and the network. This reduces unnecessary power consumption in the relay UE and also reduces latency in data communication between the remote UE and the network via the relay UE.

[0360] The method disclosed in Modification 2 of Embodiment 1 may also be applied. The method disclosed in Modification 2 of Embodiment 1 may be appropriately applied to the method by which the AMF sets individual DRXs for RAN paging UEs for relay UEs. hand That's also good. Similar effects can be achieved.

[0361] In Modification 2 of Embodiment 1, a method was disclosed in which the AMF configures the DRX settings for individual UEs for paging. However, instead of the AMF, a RAN node, such as a gNB, may configure the DRX. A gNB connected to a relay UE may configure the DRX. In this case, the gNB would process the method disclosed in Modification 2 of Embodiment 1 instead of the AMF to configure the DRX settings for RAN paging. This avoids complicating the processing. It also reduces the amount of signaling between the gNB and the AMF.

[0362] By using the method described in this disclosure, it becomes possible to transition the relay UE to the RRC_Inactive state during communication between the remote UE and the network via the relay UE. Since the relay UE can receive paging at the RAN paging DRX cycle, power consumption can be reduced. In addition, it becomes possible to individually configure the RAN paging DRX settings for the relay UE according to the generation cycle of the data that the remote UE communicates with the network. Since the relay UE can receive data at a RAN paging DRX cycle that is suitable for the generation cycle of the data that the remote UE communicates with the network, power consumption of the relay UE can be reduced. Furthermore, it becomes possible to reduce the delay in data communication between the remote UE and the network via the relay UE.

[0363] Embodiment 3. This invention discloses another method for solving the problems described in Embodiment 1.

[0364] A relay UE with UE-to-NW relay capability maintains the RRC_Connected state while performing relay operations. The RRC connection may not be released. A relay UE with UE-to-NW relay capability maintains the CM_Connected state while performing relay operations. The CM connection may not be released. A relay UE with UE-to-NW relay capability may maintain a PDU session between the relay UE and the network while performing relay operations. The PDU session may not be released.

[0365] The aforementioned processing may be performed even if a PC5-S link has been established between the remote UE and the relay UE. The period during which relay processing is performed may be defined as the period from when a PDU session for relaying is established between the relay UE and the NW until the PDU session for relaying is released.

[0366] The gNB sets DRX on the relay UE. DRX is set when the relay UE is in an RRC connection state. DRX in an RRC connection state is sometimes referred to as C-DRX. In this way, when data communication is performed between the remote UE and the network via the relay UE, the relay UE can perform DRX processing. This reduces the power consumption of the relay UE.

[0367] The gNB performs the C-DRX configuration for relay UEs. The gNB can perform C-DRX configuration for each UE. Therefore, the gNB can perform individual C-DRX configuration for relay UEs. However, in communication between a remote UE and the network via a relay UE, the remote UE generates the communication data, while the relay UE does not. For this reason, a gNB connected to a relay UE cannot perform C-DRX configuration on the relay UE that is appropriate for the services occurring between the remote UE and the network. A method to solve this problem is disclosed.

[0368] The UE provides C-DRX-related information for other UEs as requested by the UE. This information is referred to in this disclosure as C-DRX-related information requested from other UEs. The UE determines the C-DRX-related information to request from other UEs. Specific examples of requested C-DRX-related information include the DRX period, on-interval, inactivity timer, retransmission timer, HARQ inactivity timer, etc., and these may be combined.

[0369] The UE notifies the gNB of the C-DRX-related information it requests from other UEs. The gNB uses the received requested C-DRX-related information to derive the C-DRX settings for the other UE. The C-DRX settings may be individual C-DRX settings for each UE. Specific examples of C-DRX settings include the DRX period, on-interval, inactivity timer, retransmission timer, HARQ inactivity timer, etc., and these may be combined.

[0370] The requested C-DRX-related information may include information to identify which UE the request is for. Alternatively, information to identify which UE the request is for may be notified along with the requested C-DRX-related information. In this way, the node receiving the requested C-DRX-related information can recognize which UE the request is for.

[0371] The requested C-DRX-related information may include information to identify which UE made the request. Alternatively, information to identify which UE made the request may be notified along with the requested C-DRX-related information. This allows the node receiving the requested C-DRX-related information to recognize which UE requested it.

[0372] The gNB notifies other UEs of the derived individual C-DRX settings. The gNB may also notify the other UEs of the derived settings via the gNB to which they are connected. The other UEs perform DRX processing using the received individual C-DRX settings. The other UEs perform receiving operations during the DRX active period. For example, the other UEs receive PDCCH during the DRX active period. The other UEs do not receive PDCCH outside of the DRX active period. In this way, it becomes possible to notify UEs other than the UE that requested the C-DRX-related information of their individual C-DRX settings corresponding to the requested C-DRX-related information. The UEs can then perform DRX processing using the C-DRX settings configured according to the C-DRX-related information requested by the other UEs.

[0373] For example, in communication between a remote UE and a network via a relay UE, the remote UE determines the C-DRX-related information it requests from the relay UE. The remote UE notifies the gNB of the C-DRX-related information it requests from the relay UE via the relay UE. The gNB uses the received C-DRX-related information to configure the relay UE's C-DRX settings. These C-DRX settings may be individual settings for each relay UE, or they may be general settings for the relay.

[0374] As a method for notifying the relay UE of the requested C-DRX-related information from the remote UE, the method for notifying the requested RRC status information from the remote UE to the relay UE, as disclosed in Modification 1 of Embodiment 1, may be appropriately applied. Alternatively, C-DRX information may be used instead of RRC status information. Similar effects can be obtained.

[0375] As a method for notifying the gNB of the C-DRX-related information requested from the relay UE, the method disclosed in Modification 1 of Embodiment 1 for notifying the gNB of the requested RRC status information may be appropriately applied. Alternatively, C-DRX information may be used instead of RRC status information. Similar effects can be obtained.

[0376] In this way, the remote UE can notify the gNB to which the relay UE is connected of the C-DRX-related information it has decided to request from the relay UE. The gNB can then recognize the requested C-DRX settings, which UE is making the request, and which UE the request is directed to, from the received requested C-DRX-related information. The gNB then uses the received requested C-DRX-related information to configure the relay UE's C-DRX.

[0377] For example, the remote UE derives the data communication interval between the remote UE and the network from the service that communicates with the network. The remote UE may also determine whether the service is performed periodically and, if so, derive the period. Using the derived data communication interval and period, the remote UE determines the C-DRX-related information to request from the relay UE. The remote UE should configure the C-DRX-related information to request from the relay UE so that the C-DRX settings are appropriate for the derived data communication interval and period.

[0378] Alternatively, the remote UE may measure time information related to data on the PC5-S link. The remote UE may derive data communication intervals and traffic patterns from the measurement results. The methods disclosed in Embodiment 1 may be applied as appropriate. The remote UE may use the derived data communication intervals and traffic patterns to set the C-DRX related information to be requested from the relay UE. The remote UE may set the C-DRX related information to be requested from the relay UE so that the C-DRX settings are suitable for the derived data communication intervals and traffic patterns.

[0379] In this way, the remote UE can derive the C-DRX settings required by the relay UE that are suitable for services that communicate with the network.

[0380] The gNB uses the received C-DRX-related information requested by the relay UE to derive the C-DRX settings for the relay UE. The C-DRX settings may be individual settings for each relay UE. The gNB notifies the relay UE of the derived individual C-DRX settings. The relay UE can then perform DRX processing using the received individual C-DRX settings.

[0381] The gNB may configure C-DRX settings different from the C-DRX-related information requested by the relay UE. The gNB may also choose not to configure C-DRX settings. The gNB may notify the remote UE of the C-DRX settings configured on the relay UE. The remote UE can recognize the C-DRX settings configured on the relay UE. The gNB may include reason information in the notification. If the gNB configures C-DRX settings different from the C-DRX-related information requested by the remote UE, the remote UE can recognize the reason. This allows the remote UE to decide, for example, whether to make another request.

[0382] The remote UE may notify the gNB of a request to reset the C-DRX-related information requested from the relay UE. The remote UE may also notify the gNB that it does not request the relay UE to configure C-DRX. The gNB can then recognize that the remote UE has not requested the relay UE to configure C-DRX. The gNB may use this notification to decide whether to disable the C-DRX configuration for the relay UE. The gNB may also notify the relay UE that the C-DRX configuration has been disabled. In this way, the relay UE does not have to perform DRX processing using the C-DRX configuration. The gNB may also notify the remote UE that the relay UE's C-DRX configuration has been disabled. In this way, the remote UE can recognize whether or not the relay UE is performing DRX processing using the C-DRX configuration.

[0383] Even when a relay UE is connected to one or more remote UEs, the method described above should be applied to each remote UE. Each of the one or more remote UEs determines the C-DRX-related information it requests from the relay UE. Each remote UE notifies the gNB of the C-DRX-related information it requests from the relay UE. The gNB uses the C-DRX-related information it receives from each remote UE to configure one or more C-DRX settings for the relay UE. The gNB may configure the C-DRX settings for the relay UE for each remote UE. The one or more C-DRX settings may be individual C-DRX settings for each relay UE. The C-DRX settings may be for the relay only.

[0384] The gNB notifies the relay UE of the derived C-DRX settings for one or more individual relay UEs. The relay UE then performs DRX processing using the received C-DRX settings for one or more individual relay UEs. In this way, even when multiple remote UEs are connected to a relay UE, the relay UE can perform DRX processing at a C-DRX cycle that corresponds to the DRX cycle requested by each remote UE.

[0385] A remote UE may notify the relay UE of the C-DRX-related information it requests. For example, if multiple remote UEs are connected to a relay UE, the multiple remote UEs will notify the relay UE of the C-DRX-related information they request. The relay UE may use the C-DRX-related information it receives from one or more remote UEs to derive the C-DRX-related information it requests.

[0386] For example, a relay UE selects the shortest DRX period from the C-DRX-related information requested by one or more remote UEs, and sets the selected DRX period in the C-DRX-related information requested by its own UE.

[0387] The relay UE notifies the gNB of the C-DRX-related information it has derived and requested for its own UE. The gNB uses the received C-DRX-related information requested by the relay UE to configure the relay UE's C-DRX settings. These C-DRX settings may be individual settings for each relay UE. These C-DRX settings may also be for the relay as a whole. The gNB notifies the relay UE of the individual C-DRX settings it has derived. The relay UE uses the received individual C-DRX settings to perform DRX processing.

[0388] In this way, even when data is generated at a remote UE to a relay UE connected to one or more remote UEs, the delay amount due to the C-DRX cycle to the relay UE can be reduced.

[0389] The aforementioned methods should be applied as appropriate to notify the relay UE of C-DRX-related information requested from other UEs, the relay UE of the gNB of C-DRX-related information requested from its own relay UE, and the gNB of C-DRX settings to the relay UE.

[0390] Figures 23 and 24 are sequence diagrams illustrating an example of a method for communication between a UE and a NW via a relay UE in Embodiment 3. Figures 23 and 24 are connected at the boundary line BL2324. Figures 23 and 24 disclose an example in which a remote UE notifies a gNB connected to the relay UE of the C-DRX related information it requests from the relay UE. According to this example, the relay UE can perform DRX processing at the C-DRX period desired by the remote UE. In Figures 23 and 24, steps common to Figures 14 to 16 are given the same step numbers, and common explanations are omitted. Figures 23 and 24 show the relay UE maintaining RRC and CM connections.

[0391] In step ST1405, the remote UE notifies the AMF of remote UE-related information, enabling communication between the remote UE and the network. In step ST1701, the remote UE notifies the gNB of the C-DRX-related information it requests from the relay UE. The remote UE notifies the gNB of the C-DRX-related information it requests from the relay UE via the relay UE. The remote UE sets the C-DRX-related information it requests from the relay UE. For example, the remote UE derives the data generation cycle from the service-related information and uses that information to set the C-DRX-related information it requests from the relay UE, such as the DRX cycle and DRX on. interval It is advisable to configure the following. The remote UE may include information in the C-DRX related information indicating which UE is making the request to which UE. The remote UE may notify the AMF of the C-DRX related information together with the remote UE related information notified from the remote UE in step ST1405, or include it in the remote UE related information in step ST1405. This allows for early processing by the gNB.

[0392] Upon receiving the DRX-related information, the gNB becomes able to recognize the C-DRX setting for the relay UE. Furthermore, the gNB recognizes that the request is for relay communication, as it originates from a remote UE. In step ST1702, the gNB uses the paging DRX-related information requested from the relay UE to derive the C-DRX setting for the relay UE. This C-DRX setting may be an individual DRX setting for each UE. Individual C-DRX settings can be configured for each relay UE.

[0393] In step ST1703, the gNB notifies the relay UE of the C-DRX settings for the relay UE. In step ST1704, the relay UE implements the received C-DRX settings. The relay UE uses these C-DRX settings to send and receive data with the gNB.

[0394] Relay UE may support mobility. For example, Relay UE may support cell reselection processing. Relay UE may support HO processing.

[0395] This document discloses the case where a relay UE performs a Human Access Request (HO). The relay UE may perform the HO process between the source gNB and the destination gNB. The source gNB notifies the destination gNB of the relevant information of the relay UE performing the HO and the relevant information of the remote UE connected to the relay UE. The source gNB may also include this information in the HO request signaling that it notifies the destination gNB of. The destination gNB, having received the relevant information of the relay UE and the remote UE, may create association information. The destination gNB establishes a PDU session between the relay UE and the network. In this way, even in situations where the relay UE performs an HO, if data is generated for the remote UE, the network can send data to the remote UE via the destination gNB and the relay UE.

[0396] In situations where a relay UE performs a Home Order (HO), the connection with the remote UE may not be maintained. In such cases, the relay UE may notify the source gNB or destination gNB that the connection with the remote UE cannot be maintained. Alternatively, the relay UE may notify the source gNB or destination gNB of the release or discarding of the remote UE's associated information. Furthermore, the destination gNB does not need to establish a PDU session between the relay UE and the network for relay communication with the remote UE.

[0397] The source or destination gNB may notify the AMF that the connection with the remote UE will not be maintained. Alternatively, the source or destination gNB may notify the AMF of the release or discarding of the information related to the remote UE. Furthermore, the AMF does not need to establish a PDU session between the relay UE and the NW for relay communication with the remote UE.

[0398] In this way, when a relay UE performs a HO (Host Operation), if the connection between the relay UE and the remote UE is not maintained, it becomes possible to avoid establishing a PDU session and maintaining association information with the remote UE in the gNB and / or AMF. This avoids unnecessary processing, resulting in reduced malfunctions and lower power consumption for the system.

[0399] By using the method described in this disclosure, in communication between a remote UE and a network via a relay UE, the relay UE can perform DRX processing at a C-DRX cycle without having to transition the relay UE to the RRC_Idle or RRC_Inactive state. This allows for lower power consumption of the relay UE. Furthermore, C-DRX settings can be individually configured for the relay UE according to the data generation interval and traffic pattern of the data communicated by the remote UE with the network. Since the relay UE can perform DRX processing with a C-DRX setting suitable for the data generation interval and traffic pattern of the data communicated by the remote UE with the network, lower power consumption of the relay UE is possible. In addition, delays in data communication between the remote UE and the network via the relay UE can be reduced.

[0400] gNB disclosed setting DRX to relay UE. As another example, gNB set SPS to relay UE. (semi-persistent scheduling) You may also configure it as follows: gNB to relay UE to CG (configured grant) You may also configure this. A relay UE with SPS or CG configured may activate the transmit / receive processing using the resources configured in the SPS or CG. By doing so, it is possible to reduce the power consumption of the relay UE when data communication is performed between the remote UE and the network via the relay UE.

[0401] Modification 1 of Embodiment 3. This invention discloses another method for solving the problems described in Embodiment 1.

[0402] Embodiment 3 disclosed a method in which a remote UE notifies a gNB of the C-DRX-related information it requests from a relay UE, and the gNB uses this information to configure the C-DRX settings for the relay UE. This modification 1 of Embodiment 3 discloses a method that uses traffic patterns instead of C-DRX-related information.

[0403] The remote UE derives the traffic pattern in communication with the network. The method for deriving the traffic pattern may be the method disclosed in Embodiment 3, as appropriate. For example, the remote UE derives the traffic pattern between the remote UE and the network from a service that communicates with the network. For example, the remote UE may measure time information related to data on the PC5-S link and derive the traffic pattern from the measurement results.

[0404] In communication between a remote UE and the network via a relay UE, the remote UE derives a traffic pattern. The remote UE then notifies the gNB of the traffic pattern via the relay UE.

[0405] Information may be provided indicating which UE the traffic pattern belongs to. This information may include, for example, a UE identifier. Information may be provided indicating which service the traffic pattern belongs to. This information may include, for example, a service identifier. Information may be provided indicating which QoS flow the traffic pattern belongs to. This QoS flow may be a PC5 QoS flow. For example, a QoS flow identifier may be used. The remote UE may notify the gNB of some or all of this information, along with the traffic pattern, via the relay UE. In this way, the gNB can recognize which UE the traffic pattern belongs to, which service the traffic pattern belongs to, and which QoS flow the traffic pattern belongs to.

[0406] The gNB uses traffic patterns to configure the C-DRX settings of the relay UE. These C-DRX settings may be configured for each individual relay UE, or they may be configured for the relays as a whole.

[0407] The method for notifying the relay UE of the traffic pattern from the remote UE may be appropriately applied to the method for notifying the relay UE of the desired RRC status information from the remote UE, as disclosed in Modification 1 of Embodiment 1. Alternatively, a traffic pattern may be used instead of RRC status information. Similar effects can be obtained.

[0408] The method for notifying the gNB of the traffic pattern from the relay UE may be appropriately applied to the method for notifying the gNB of the desired RRC status information from the relay UE, as disclosed in Modification 1 of Embodiment 1. Alternatively, a traffic pattern may be used instead of RRC status information. Similar effects can be obtained.

[0409] This allows the relay UE to notify the gNB to which it is connected of the traffic pattern derived by the remote UE.

[0410] The gNB derives the C-DRX settings for the relay UE using the traffic patterns received from the remote UE. The C-DRX settings may be individual settings for each UE. The gNB notifies the relay UE of the derived individual C-DRX settings. The relay UE can then perform DRX processing using the received individual C-DRX settings.

[0411] The gNB may notify the remote UE of the C-DRX settings configured on the relay UE. The remote UE can then recognize the C-DRX settings configured on the relay UE. The gNB may include reasoning information in the notification. For example, the remote UE can decide whether to change the frequency of traffic pattern notifications or whether to notify traffic patterns at all.

[0412] Even if a relay UE is connected to one or more remote UEs, the method described above should be applied to each remote UE. Each of the one or more remote UEs determines its own traffic pattern. Each remote UE notifies the gNB of its traffic pattern. The gNB uses the traffic patterns received from each remote UE to configure one or more C-DRX settings for the relay UE. The gNB may configure the C-DRX settings for each remote UE individually. These one or more C-DRX settings may be individual C-DRX settings for each relay UE. These C-DRX settings may be for relays only.

[0413] The gNB notifies the relay UE of the derived C-DRX settings for one or more individual relay UEs. The relay UE then performs DRX processing using the received C-DRX settings for one or more individual relay UEs. In this way, even when multiple remote UEs are connected to the relay UE, the relay UE can perform DRX processing at a C-DRX cycle that corresponds to the traffic pattern of each remote UE.

[0414] While the above disclosed that the remote UE derives the traffic pattern, the relay UE may also derive the traffic pattern of the communication between the remote UE and the network. For example, the relay UE measures the communication data of the PC5 link with the remote UE. The method disclosed in Embodiment 1 may be applied as appropriate.

[0415] The relay UE notifies the gNB of the derived traffic pattern of communication between the remote UE and the network. There may be one or more remote UEs. The relay UE notifies the gNB of the traffic pattern of communication between the remote UE and the network that it derived for each remote UE. The gNB uses the traffic pattern of communication between the remote UE and the network received from the relay UE to configure one or more C-DRX settings for the relay UE. These one or more C-DRX settings may be individual C-DRX settings for each relay UE. These C-DRX settings may be for relays only.

[0416] The gNB notifies the relay UE of the derived C-DRX settings for one or more individual relay UEs. The relay UE then performs DRX processing using the received C-DRX settings for one or more individual relay UEs. In this way, even when multiple remote UEs are connected to a relay UE, the relay UE can perform DRX processing at a C-DRX cycle that corresponds to the traffic pattern of communication between each remote UE and the network.

[0417] This may be combined with the method disclosed in Embodiment 3. For example, a remote UE may notify the relay UE of the traffic pattern. For example, if multiple remote UEs are connected to the relay UE, the multiple remote UEs notify the relay UE of the traffic pattern. The relay UE uses the traffic pattern received from one or more remote UEs to derive the C-DRX-related information requested by itself.

[0418] The relay UE notifies the gNB of the C-DRX-related information it has derived and requested for itself. The gNB uses the received C-DRX-related information requested for the relay UE to configure the C-DRX settings of the relay UE. These C-DRX settings may be individual settings for each relay UE. These C-DRX settings may also be general settings for the relay. The gNB notifies the relay UE of the individual C-DRX settings it has derived. The relay UE uses the received individual C-DRX settings to perform DRX processing.

[0419] In this way, even when data is generated at a remote UE to a relay UE connected to one or more remote UEs, the delay amount due to the C-DRX cycle to the relay UE can be reduced.

[0420] Figures 25 and 26 are sequence diagrams illustrating an example of a method for communication between a UE and a NW via a relay UE, according to a modification 1 of Embodiment 3. Figures 25 and 26 are connected at the boundary line BL2526. Figures 25 and 26 disclose an example in which a remote UE notifies a gNB connected to the relay UE of a traffic pattern. According to this example, the relay UE can perform DRX processing at a C-DRX cycle corresponding to the traffic pattern. In Figures 25 and 26, steps common to Figures 23 and 24 are given the same step numbers, and common explanations are omitted.

[0421] In step ST1405, the remote UE notifies the AMF of remote UE-related information, enabling communication between the remote UE and the network. In step ST1801, the remote UE notifies the gNB of the traffic pattern. The remote UE notifies the gNB of the traffic pattern via the relay UE. The remote UE may derive the traffic pattern, for example, from service-related information communicated between the remote UE and the network. The traffic pattern may be notified together with the remote UE-related information notified from the remote UE to the AMF in step ST1405, or included in the remote UE-related information in step ST1405. This allows the gNB to process the information early.

[0422] Upon receiving a traffic pattern from a remote UE, the gNB, in step ST1802, uses the traffic pattern to derive the C-DRX setting for the relay UE. This C-DRX setting may be an individual DRX setting for each UE. Individual C-DRX settings can be configured for each relay UE.

[0423] In step ST1803, the gNB notifies the relay UE of the C-DRX settings for the relay UE. In step ST1804, the relay UE implements the received C-DRX settings. The relay UE uses these C-DRX settings to send and receive data with the gNB.

[0424] By using the method described in this disclosure, in communication between a remote UE and a network via a relay UE, the relay UE can perform DRX processing at a C-DRX cycle without having to transition the relay UE to the RRC_Idle or RRC_Inactive state. This allows for lower power consumption of the relay UE. Furthermore, C-DRX settings can be individually configured for the relay UE according to the traffic pattern of the data communicated by the remote UE with the network. Since the relay UE can perform DRX processing with a C-DRX setting suitable for the traffic pattern of the data communicated by the remote UE with the network, lower power consumption of the relay UE is possible. In addition, delays in data communication between the remote UE and the network via the relay UE can be reduced.

[0425] This document discloses a method for notifying the remote UE, the relay UE, and the gNB connected to the relay UE of information regarding communication between the remote UE and the network via a relay UE. Figure 27 is a sequence diagram showing an example of a method for notifying the remote UE, the relay UE, and the gNB connected to the relay UE of information regarding communication between the remote UE and the network via a relay UE.

[0426] The gNB notifies the relay UE of the setting for reporting information about communication between the remote UE and the network via the relay UE. RRC signaling may be used for this notification. For example, the Other Config message may be used. The relay UE that receives the setting for reporting information may notify the remote UE of the setting for reporting information. The relay UE may notify the remote UE of the setting for reporting information. This information may include, for example, the RRC status information requested from other UEs, C-DRX related information requested from other UEs, traffic patterns, etc.

[0427] PC5-S signaling may be used to notify the remote UE of the setting for reporting this information from the relay UE. This allows for early notification even if the PC5 RRC setting is not configured. Alternatively, the PC5 RRC signaling may be used. This has high compatibility with the RRC processing from the gNB to the relay UE and avoids complicating the process. For example, a message for setting up UE assistance information reporting may be provided. Alternatively, the PC5 MAC signaling may be used. This allows for early notification with low error. Alternatively, PSCCH or PSSCH may be used. This allows for even earlier notification.

[0428] Upon receiving the information report settings, the remote UE derives the information based on those settings. For example, if RRC status information to be requested from other UEs is set, the remote UE derives the RRC status information to be requested from other UEs. The remote UE then notifies the relay UE of the derived RRC status information. As a notification method, the method described above for notifying the remote UE of the information report settings may be applied as appropriate. As RRC signaling, for example, a UE assistance information message may be provided.

[0429] Applicable RRC status information Upon receiving the signal, the relay UE communicates to the gNB the RRC status information This will be notified. As a notification method, the method described above for notifying the relay UE of the setting for reporting this information should be applied as appropriate. For example, a UE assistance information message may be used as RRC signaling. In this way, the gNB will be able to obtain information from the remote UE regarding communication between the remote UE and the network via the relay UE.

[0430] The gNB can acquire the information mentioned above, such as RRC status information requested from the relay UE, C-DRX related information requested from the relay UE, and traffic pattern information. Using this information, the gNB can control the connection status to the relay UE and the DRX settings.

[0431] Embodiment 4. This invention discloses another method for solving the problems described in Embodiment 1.

[0432] This document describes how to perform DRX processing in direct UE-to-UE communication on PC5. It also discloses the DRX configuration method for direct UE-to-UE communication on PC5. In this disclosure, DRX in direct UE-to-UE communication on PC5 may be referred to as PC5 DRX. Furthermore, in direct UE-to-UE communication on PC5, the transmitting UE may be referred to as UE-TX, and the receiving UE as UE-RX. In direct UE-to-UE communication on PC5, there are two methods: one where UE-TX selects and reserves SL communication resources (called Mode 2), and another where the gNB to which UE-TX is connected schedules SL communication resources (called Mode 1).

[0433] This document discloses the PC5 DRX configuration in Mode 2. The UE-TX configures the PC5 DRX. The UE-TX notifies the UE-RX, which is the opposing UE in direct UE-to-UE communication via PC5, of the PC5 DRX configuration. The UE-RX uses the PC5 DRX configuration received from the UE-TX to perform DRX processing in direct UE-to-UE communication via PC5.

[0434] UE-TX may notify UE-RX of the PC5 DRX configuration using PC5-S signaling. This allows for early notification. Alternatively, UE-TX may notify UE-RX of the PC5 DRX configuration using PC5's RRC signaling. UE-TX may also notify UE-RX of the PC5 DRX configuration as an AS configuration. Alternatively, UE-TX may notify UE-RX of the PC5 DRX configuration using PC5's MAC signaling. Alternatively, UE-TX may notify UE-RX of the PC5 DRX configuration using PSCCH or PSSCH. This allows for dynamic and rapid notification after PC5 DRX is configured.

[0435] The activation or deactivation of the PC5 DRX may be configurable. For example, the PC5 DRX setting can be notified via PC5-S signaling or PC5 RRC signaling, and PC5 DRX activation / deactivation information can be notified via PC5 MAC signaling, or via PSCCH or PSSCH. Upon receiving the PC5 DRX activation / deactivation information, the UE-RX will perform the PC5 DRX activation / deactivation according to that information. In this way, the PC5 DRX setting can be notified in advance, and the activation or deactivation of the PC5 DRX process can be performed dynamically.

[0436] The PC5 DRX setting in Mode 1 is disclosed. The gNB sets PC5 DRX for the UE-TX. The gNB notifies the UE-TX of the PC5 DRX setting. The UE-TX cannot perform PC5 DRX processing with the UE-RX unless it recognizes the PC5 DRX setting. Therefore, by notifying the UE-TX of the PC5 DRX setting from the gNB, the UE-TX becomes able to perform PC5 DRX processing. Upon receiving the PC5 DRX setting from the gNB, the UE-TX notifies the UE-RX of the PC5 DRX setting. The UE-RX cannot perform PC5 DRX processing with the UE-TX unless it recognizes the PC5 DRX setting. Therefore, by receiving the PC5 DRX setting set by the gNB from the UE-TX, the UE-RX becomes able to perform PC5 DRX processing.

[0437] The gNB may notify the UE-TX of the PC5 DRX configuration via RRC signaling. Alternatively, the gNB may notify the PC5 DRX configuration via MAC signaling. Alternatively, the gNB may notify the PC5 DRX configuration via PDSCH. Notification of the PC5-DRX configuration from the UE-TX to the UE-RX should be appropriately applied using the methods disclosed in Mode 2.

[0438] The PC5 DRX may be configurable for activation or deactivation. For example, the gNB notifies the UE-TX of the PC5 DRX configuration via RRC signaling. The UE-TX notifies the UE-RX of the PC5 DRX configuration via PC5 RRC signaling. The gNB notifies the UE-TX of the PC5 DRX activation / deactivation information via MAC signaling or PDCCH. The UE-TX notifies the UE-RX of the PC5 DRX activation / deactivation information via PSCCH or PSSCH. Upon receiving the PC5 DRX activation / deactivation information, the UE-RX performs the PC5 DRX activation / deactivation according to the information.

[0439] In addition to this, it would be desirable for the PC5 DRX settings to be notified before the PC5 DRX activation / deactivation notification. By doing so, even in Mode 1, the PC5 DRX settings can be notified in advance, and the activation or deactivation of the PC5 DRX process can be performed dynamically.

[0440] The UE-TX may request the gNB to configure PC5 DRX. The UE-TX notifies the gNB of the PC5 DRX configuration request. The UE-TX may also notify the gNB of service-related information for PC5 communication with the UE-RX. The UE-TX may also notify the gNB of the SL traffic pattern for PC5 communication with the UE-RX. The UE-TX may notify the gNB of this information together with the PC5 DRX configuration request, or include it in the PC5 DRX configuration request. The gNB may use this information to configure PC5 DRX for the UE-TX. The gNB will then be able to configure PC5 DRX to be suitable for PC5 communication between the UE-TX and the UE-RX.

[0441] In Mode 1, when the gNB performs dynamic scheduling for the UE-TX, scheduling outside of the PC5 DRX active period may be disallowed. The UE-TX does not need to receive scheduling from the gNB, such as PDCCH, on the Uu while PC5 communication is inactive due to the PC5 DRX setting. This reduces the power consumption of the UE-TX.

[0442] UE-TX is DCI (Downlink Control Information) The time required for processing from receiving the signal to transmitting PSCCH or PSSCH on PC5, or the time set for such processing, may be taken into consideration. For example, if gNB performs dynamic scheduling for UE-TX, scheduling may not be permitted from the transition timing outside the active period of PC5 DRX until a predetermined timing (for example, earlier than the transition timing to the active period, or the time set for such processing). UE-TX becomes capable of transmitting PSCCH or PSSCH immediately after the transition to the active period of PC5 DRX.

[0443] The gNB may configure the DRX settings between the gNB and the UE-TX using the PC5 DRX settings. In this disclosure, the DRX settings between the gNB and the UE-TX may be referred to as the Uu DRX settings. For example, the gNB may adjust the PC5 DRX settings and the Uu DRX settings so that their active periods match (in other words, align them). Alternatively, the gNB may adjust the PC5 DRX settings and the Uu DRX settings so that their active periods are continuous. Alternatively, the gNB may adjust the PC5 DRX settings and the Uu DRX settings so that, even if their active periods are discontinuous, the period from the start of one active period to the end of both active periods is minimized. For example, the gNB may configure the Uu DRX settings and the PC5 DRX settings taking into account the time required for processing from the reception of DCI to the transmission of PSCCH or PSSCH at PC5, or the time set for such processing. For example, the Uu DRX active transition timing may be set earlier than the PC5 DRX active transition timing by the time required for the above process or the time set for the above process.

[0444] This approach makes it possible to reduce the power consumption of the UE-TX.

[0445] In Mode 1, when the gNB sets the PC5 CG (Configured Grant) for the UE-TX, the UE-TX, upon receiving the PC5 CG setting from the gNB, may notify the UE-RX of the PC5 CG setting. For example, the UE-RX can recognize the CG setting configured on the UE-TX and use that CG setting to receive data from the UE-TX. The UE-RX only needs to receive data from the UE-TX at the resource timing set by the CG. This allows for lower power consumption of the UE-RX. Furthermore, by using CG, when data is generated on the UE-TX, the UE-TX can transmit the data to the UE-RX with low latency.

[0446] The gNB may configure both PC5's CG and PC5's DRX for UE-TX. For example, PC5's CG may be used when low latency is required, and PC5's DRX may be used when low latency is not required.

[0447] The gNB may be prohibited from simultaneously setting PC5's CG and PC5's DRX for UE-TX. This would help avoid complicating the process.

[0448] The PC5 DRX may be configured for each UE or for each UE-TX. When performing data communication with multiple UE-RXs, it is preferable to perform the data communication with those multiple UE-RXs during the DRX active period set for the UE-TX.

[0449] PC5 DRX may be configured for each UE-RX. When performing data communication with multiple UE-TXs, it is preferable to perform data communication with those multiple UE-TXs during the DRX active period configured for each UE-RX.

[0450] PC5 DRX may be configured for each opposing UE pair. This allows for PC5 DRX settings appropriate for the services communicated between the opposing UE pairs. PC5 DRX may also be configured for each PC5-S link. This allows for PC5 DRX settings appropriate for the services communicated between the opposing UE pairs. PC5 DRX may also be configured for each PC5 QoS flow. This allows for PC5 DRX settings appropriate for the QoS of the services communicated between the opposing UE pairs.

[0451] The aforementioned PC5 DRX settings may be one or multiple. Furthermore, multiple PC5 DRX settings may be combined. This allows for flexible DRX configuration and enables PC5 DRX settings suitable for diverse SL traffic patterns.

[0452] The following (1) to (8) are provided as specific examples of PC5 DRX configuration information.

[0453] (1)PC5 DRX cycle.

[0454] (2) PC5 DRX ON interval.

[0455] (3) PC5 DRX offset.

[0456] (4) PC5 DRX in-activity period.

[0457] (5)PC5 DRX retransmission period.

[0458] (6) PC5 DRX retransmission inactivity period.

[0459] (7) PC5 DRX frequency band.

[0460] (8) A combination of (1) through (7).

[0461] Regarding (1) above, multiple PC5 DRX periods may be set. For example, multiple PC5 DRX settings with different periods may be set. For example, period A and a longer period B may be set. Initially, PC5 DRX processing is performed with period A, and period A is performed for a predetermined period or a predetermined number of times. If no data is generated during this time, it transitions to period B. If data is generated during the PC5 DRX processing of period B, it transitions to period A. In this way, PC5 DRX settings can be flexibly implemented according to the frequency of communication occurrence.

[0462] The PC5 DRX ON interval in (2) above may be set to be longer than the SL resource selection window period in mode 2. Alternatively, PC5 DRX on The interval may be set to the same duration as the SL resource selection window period. This ensures that at least one SL resource selected during the SL resource selection window period is included within the PC5 DRX-on interval. During the PC5 DRX-on interval, PSCCH and PSSCH transmissions become possible with that SL resource.

[0463] The PC5 DRX offset in (3) above may be set in conjunction with the start timing of the SL resource selection window in Mode 2. This allows the PC5 DRX on interval to be set so that the SL resource selected during the SL resource selection window period falls within that interval.

[0464] Items (1) through (6) mentioned above may be managed using a timer.

[0465] The PC5 DRX frequency band mentioned in (7) above indicates the frequency resources used during the PC5 DRX active period. These resources may be in subcarrier units, Resource Block (RB) units, or subchannel units. They may also be Band Width Parts (BWP). The carrier frequency may also be set as the PC5 DRX frequency band. In Mode 2, the PC5 DRX frequency band may be set to a frequency band that includes the frequencies of the SL resource selection and reserved resources. In this way, the UE-RX can limit the frequency band in which it searches for transmissions from the UE-TX. This simplifies processing and reduces the power consumption required for searching.

[0466] Figure 28 is a conceptual diagram showing a first example of the PC5 DRX setting for Embodiment 4. In Figure 28, the PC5 DRX setting is PC5 DR X The period, PC5 DRX offset, and PC5 DRX on interval are set. The PC5 DRX on interval occurs at the PC5 DRX period. The start of the PC5 DRX on interval is set by the PC5 DRX offset. The PC5 DRX offset may be set not only in subframe units or wireless frame units, but also in symbol units or slot units. This allows for finer timing settings.

[0467] Resources selected and reserved for SL communication from UE-TX to UE-RX become active during the PC5 DRX active period. During the PC5 DRX active period, data can be transmitted from UE-TX to UE-RX using the reserved resources. Outside of the PC5 DRX active period, data cannot be transmitted from UE-TX to UE-RX using the reserved resources. In the example in Figure 28, the PC5 DRX active period is the PC5 DRX on interval. Outside of the PC5 DRX active period is the period excluding the PC5 DRX on interval.

[0468] Figure 29 is a conceptual diagram showing a second example of the PC5 DRX settings for Embodiment 4. In Figure 29, the PC5 DRX inactivity period is set as the PC5 DRX setting. The differences between Figure 29 and Figure 28 will be explained below. PC5 DRX ON interval If a PSCCH or PSSCH occurs during this period, the PC5 DRX active period will be set for the duration of the PC5 DRX inactivity period, starting from the occurrence of the PSCCH or PSSCH. PC5 DRX ON interval If data is transmitted from UE-TX to UE-RX during this period, the PC5 DRX active period may be set to last for the duration of the PC5 DRX inactivity period from the time of the data transmission.

[0469] If a PSCCH or PSSCH occurs during the PC5 DRX inactivity period, the PC5 DRX active period will continue for an additional period from the time of the PSCCH or PSSCH occurrence to the PC5 DRX inactivity period. If data is transmitted from UE-TX to UE-RX during the PC5 DRX inactivity period, the PC5 DRX active period may be continued for an additional period from the time of the data transmission to the PC5 DRX inactivity period.

[0470] In this disclosure, PSCCH, PSSCH, or data in PC5 may be referred to simply as "data."

[0471] The timing may be predetermined statically by a standard or similar specification. Alternatively, the timing may be included in the PC5 DRX configuration information. For example, the start of the PC5 DRX inactivity period may be the start time of the next slot after the slot in which data was generated. For example, it may be defined by a symbol instead of a slot.

[0472] If no data is generated within the PC5 DRX inactivity period following the last PSCCH occurrence, the PC5 DRX will transition to an inactive period. The PC5 DRX will remain in an inactive period until the start of the next PC5 DRX on interval.

[0473] Resources selected and reserved for SL communication from UE-TX to UE-RX become active during the PC5 DRX active period. During the PC5 DRX active period, data can be sent from UE-TX to UE-RX using the reserved resources. Outside of the PC5 DRX active period, data cannot be sent from UE-TX to UE-RX using the reserved resources. In the example in Figure 29, the PC5 DRX active period is the period from the start of the PC5 DRX on interval to the end of the PC5 DRX inactivity period. Outside of the PC5 DRX active period is the period from the end of the PC5 DRX inactivity period to the start of the PC5 DRX on interval.

[0474] This document discloses the processing method for PC5 DRX in Mode 2. When data is generated, the UE-TX searches for SL communication resources before the PC5 DRX on interval. The UE-TX may also search for SL communication resources in advance, not just when data is generated. Resource selection and reservation become possible early when data is generated. The UE-TX selects and reserves resources for the PC5 DRX on interval. If the UE-TX runs out of reserved SL communication resources, it selects and reserves SL communication resources again. The UE-TX may select and reserve resources multiple times during the PC5 DRX on interval. In addition, the UE-TX may select and reserve resources multiple times not only during the PC5 DRX on interval, but also during the PC5 DRX active period.

[0475] The number of resources reserved for SL communication (sometimes referred to as the reselection counter) may be limited to within the PC5 DRX on interval. This makes it possible to improve the efficiency of resource usage for other UEs. If the number of resources reserved for SL communication is limited to within the PC5 DRX on interval, resource selection and reservation may be performed again during the PC5 DRX on interval. If the reselection counter for a reserved resource becomes 0 within the DRX on interval, the resource may be selected and reserved again. The number of resources reserved for SL communication (sometimes referred to as the reselection counter) does not have to be limited to within the PC5 DRX on interval. This makes it possible to reduce the processing that UE-TX has to perform again to select and reserve resources during the PC5 DRX active period. This makes it possible to avoid the complexity caused by this processing.

[0476] If data is transmitted within the PC5 DRX on interval, the PC5 DRX in-activity period begins. If data is transmitted within the PC5 DRX in-activity period, the PC5 DRX in-activity period begins again. If the SL communication resources reserved at the start of the PC5 DRX in-activity period are less than the resources available during the PC5 DRX in-activity period, the UE-TX may select and reserve resources again. If the reselection counter for the resources reserved for SL communication becomes 0 during the PC5 DRX in-activity period, the UE-TX may select and reserve the SL communication resources again. This method allows for the reservation of SL communication resources during the PC5 DRX active period.

[0477] Repetition transmission may be performed in SL communication. Repetition transmission may be performed within the active period of the PC5 DRX. Repetition transmission may initiate the PC5 DRX inactivity period. The UE-TX may perform repetition transmission using the SL communication resources during the active period of the PC5 DRX. Repetition transmission can improve the reception quality at the UE-RX.

[0478] If the transition occurs outside the PC5 DRX active period, the UE-TX may release the reserved SL communication resources. Information indicating the release of SL communication resources may be provided. If such information is transmitted, it is preferable not to transition during the PC5 DRX inactivity period. When the UE-TX releases the reserved SL communication resources, it transmits this information. The UE-TX may, for example, include this information in the PSCCH. This makes it receivable by other UEs. Other UEs can recognize that the resources reserved by the UE-TX that transmitted the information have been released. This makes it possible to improve the utilization efficiency of SL communication resources. Other control channels or signals may be provided for transmitting this information.

[0479] For example, UE-TX may transmit the information on the last resource during the PC5 DRX inactivity period. Alternatively, UE-TX may transmit the information on the first resource after the transition outside the PC5 DRX active period. This allows the information to be transmitted immediately before or after the transition outside the PC5 DRX active period.

[0480] The UE-TX uses the SL communication resources during the PC5 DRX's active period to schedule data transmission to the UE-RX and transmits data according to that schedule. If no PC5 DRX inactivity period is set, and the amount of data exceeds the amount that can be transmitted in a DRX-on interval, the data may be transmitted in the next DRX-on interval.

[0481] The method for PC5 DRX processing in Mode 1 is disclosed. The UE-TX should perform DRX processing according to the PC5 DRX settings received from the gNB. The PC5 DRX settings should be appropriately applied using the method described above. The method for DRX processing should be appropriately applied using the method disclosed for Mode 2. However, the UE-TX should not perform resource selection and reservation, but should use the PC5 DRX resources received from the gNB.

[0482] This document discloses the DRX processing on the UE-RX in Mode 1 and Mode 2. The UE-RX uses the PC5 DRX settings received from the UE-TX to derive the start timing of the PC5 DRX on interval, and receives the PSCCH or PSSCH from the UE-TX during the PC5 DRX on interval. In LTE, the SCI, which is the control information for PC5, is included in the PSCCH. In NR, this information is included in both the PSCCH and PSSCH. By receiving the PSCCH or PSSCH, the UE-RX becomes able to receive the SCI from the UE-TX. The UE-RX receives data according to the scheduling information of the received SCI.

[0483] When a UE-RX receives data from a UE-TX at a PC5 DRX ON interval, if an in-activity period is set, it will receive PSCCH or PSSCH signals from the UE-TX from the time of data reception until the PC5 DRX in-activity period. If there is data during the PC5 DRX in-activity period, it will enter another PC5 DRX in-activity period. If there is no data during the PC5 DRX in-activity period, it will transition to the PC5 DRX outside active period after the end of the PC5 DRX in-activity period. The UE-RX will stop receiving PSCCH or PSSCH signals outside the PC5 DRX active period.

[0484] The UE-RX uses the PC5 DRX cycle to receive PSCCH or PSSCH from the UE-TX at the next PC5 DRX on interval. In this way, the UE-RX receives PSCCH, PSSCH, or data during the PC5 DRX active period, and does not receive any PSCCH, PSSCH, or data outside of the PC5 DRX active period.

[0485] Thus, by configuring PC5 DRX settings between UE-TX and UE-RX during direct UE-to-UE communication via PC5, the power consumption of the UEs can be reduced.

[0486] NR is considering support for unicast and groupcast communication in PC5. For unicast and groupcast, HARQ with feedback is being considered. This document discloses the method for retransmitting HARQ when PC5 DRX is configured.

[0487] A retransmission period may be set. It is advisable to set the aforementioned PC5 DRX retransmission period. If a retransmission occurs, the UE-TX will perform the retransmission within the set PC5 DRX retransmission period. Alternatively, a period may be set between the receipt of the HARQ feedback signal and the retransmission. It is advisable to set the aforementioned PC5 DRX retransmission inactivity period. After receiving the feedback signal, the UE-TX will not perform a retransmission during the DRX retransmission inactivity period. The UE-TX may start a PC5 DRX retransmission period at the end of the PC5 DRX retransmission inactivity period.

[0488] Figure 30 is a conceptual diagram showing a third example of PC5 DRX settings for Embodiment 4. The PC5 DRX settings include a PC5 DRX retransmission period and a PC5 DRX retransmission inactivity period. Figure 30 primarily explains the differences from Figure 29. If data is generated within the PC5 DRX on-interval, the PC5 DRX active period continues for an additional duration equal to the PC5 DRX inactivity period from the time of data generation. If no data is transmitted from UE-TX to UE-RX within the PC5 DRX inactivity period, the PC5 DRX active period ends, and the system transitions to the PC5 DRX outside-active period.

[0489] Within the PC5 DRX ON interval, the UE-RX receives data transmitted from the UE-TX to the UE-RX. The UE-RX sends a feedback signal to the UE-TX at the timing set for feedback (feedback timing). The UE-RX may also send the feedback signal using the feedback channel (PSFCH). It is preferable to use the Ack / Nack for the received data as the feedback signal.

[0490] The feedback timing may be set by the UE-TX. The UE-TX notifies the UE-RX of the feedback timing. The UE-TX may also notify the UE-RX of feedback resource information. The UE-TX may notify the feedback timing information together with, or included in, the feedback resource information. The UE-TX may notify the resource information and timing information via the PC5's RRC signaling. The UE-TX may notify the resource information and timing information by including it in the AS settings. Alternatively, the UE-TX may notify the resource information and timing information by including it in the PC5's MAC signaling. Alternatively, the UE-TX may notify the resource information and timing information by including it in the SCI. Early and dynamic notification becomes possible.

[0491] The reselection counter for resources reserved for SL communication may be set separately for initial transmission and feedback. Alternatively, the reselection counter for resources reserved for SL communication may be set for both initial transmission and feedback. Multiple HARQs may be processed in SL communication. The reselection counter for resources reserved for SL communication may be set for each HARQ.

[0492] The feedback timing may be set by the gNB. The feedback resources may also be set by the gNB. For example, in mode 1, the gNB notifies the UE-TX of this information along with other scheduling information. The UE-TX may notify the UE-RX of the received feedback timing and feedback resource information. The gNB may notify the UE-TX of the resource information and timing information by including it in the Uu's RRC signaling. Alternatively, the gNB may notify the UE-TX of the resource information and timing information by including it in the Uu's MAC signaling. Alternatively, the gNB may notify the UE-TX of the resource information and timing information by including it in the DCI. The methods described above may be applied as a way to notify the UE-TX of this information to the UE-RX.

[0493] The transmission and reception of feedback signals may occur outside of the PC5 DRX active period.

[0494] For example, as shown in Figure 30, the transmission and reception of the feedback signal may occur after the end of the PC5 DRX inactivity period. The feedback timing may be set to a period longer than the PC5 DRX inactivity period. The UE-RX transmits the feedback signal at the set feedback timing after the end of the PC5 DRX inactivity period. The UE-TX receives the feedback signal at the set feedback timing.

[0495] The UE-TX retransmits if it receives a Nack at the configured feedback timing, or if it receives nothing. The UE-TX searches for, selects, and reserves resources for SL communication to be used within the PC5 DRX retransmission period, and retransmits using the reserved resources within the PC5 DRX retransmission period. The UE-RX receives the retransmission from the UE-TX within the PC5 DRX retransmission period. The UE-RX receives PSCCH and PSSCH from the UE-TX and receives the retransmitted data within the PC5 DRX retransmission period. The PC5 DRX retransmission period becomes the PC5 DRX active period. In this way, retransmission processing can be performed even when the PC5 DRX setting is configured.

[0496] Resending may be applied to the decision to transition to a PC5 DRX in-activity period. If a retransmission occurs during a PC5 DRX on interval or PC5 DRX in-activity period, the system may transition to another PC5 DRX in-activity period. This allows for setting PC5 DRX active periods in response to data generation (including retransmitted data). This is particularly useful when feedback timings are set to be short.

[0497] Resentments may not be applied to the decision to transition to the PC5 DRX inactivity period. Even if a retransmission occurs during the PC5 DRX on interval or PC5 DRX inactivity period, a further transition to the PC5 DRX inactivity period will not occur. This makes it possible to distinguish between retransmissions and initial transmissions. The PC5 DRX active period can be set according to the occurrence of initial transmission data, regardless of the retransmission process. This is effective, for example, when communication quality is good and retransmissions are infrequent.

[0498] Figure 31 is a conceptual diagram showing a fourth example of the PC5 DRX configuration for Embodiment 4. Figure 31 shows the case where retransmission is applied to the decision to transition to the PC5 DRX inactivity period. The main points to be explained in Figure 31 are the differences from Figure 29. If data is generated within the PC5 DRX on interval, the PC5 DRX active period is extended by the PC5 DRX inactivity period from the time the data is generated.

[0499] For example, the transmission and reception of feedback signals may occur within the PC5 DRX inactivity period. The feedback timing may be set to a period shorter than the PC5 DRX inactivity period. The UE-RX transmits the feedback signal at the set feedback timing after the end of the PC5 DRX inactivity period. The UE-TX receives the feedback signal at the set feedback timing.

[0500] The UE-TX will retransmit if it receives a Nack at the configured feedback timing, or if it receives nothing. The UE-TX will retransmit within the PC5 DRX in-activity period. If the UE-TX retransmits within the PC5 DRX in-activity period, the PC5 DRX in-activity period will start again. If no data (including retransmitted data) is sent from the UE-TX to the UE-RX within the PC5 DRX in-activity period, the PC5 DRX active period will end, and the system will move to the PC5 DRX out-of-activity period.

[0501] The UE-RX only needs to receive data (including retransmitted data) from the UE-TX during the PC5 DRX active period. The UE-RX should receive the PC5 DRX interval, PC5 DRX inactivity period, PSCCH, and PSSCH, and receive data (including retransmitted data) from the UE-TX. The processing method in the PC5 DRX configuration disclosed in Figure 29 is a suitable method for achieving this.

[0502] This approach avoids complicating the PC5 DRX processing between UE-TX and UE-RX.

[0503] In the example shown in Figure 31, the case where neither the PC5 DRX retransmission period nor the PC5 DRX retransmission inactivity period is set is disclosed. However, both the PC5 DRX retransmission period and the PC5 DRX retransmission inactivity period may be set. For example, both periods can be set so that the PC5 DRX retransmission period is included within the PC5 DRX inactivity period. Although this complicates the PC5 DRX processing between UE-TX and UE-RX, it allows for the application of a unified processing method, including cases where the PC5 DRX retransmission period is set outside the PC5 DRX inactivity period. This allows for flexible setting of the retransmission period and avoids complicating processing in such cases.

[0504] The method described above discloses the use of Ack / Nack in HARQ feedback as feedback information. Other feedback information may be used. Other feedback information should be applied as appropriate when feedback timing and feedback resources are set by UE-TX or gNB. Similar effects can be obtained.

[0505] In this disclosure, the UE from which the service data originates is designated as UE-TX. For example, if UE-TX is UE1 and UE-RX is UE2, and service data originates in UE2 and is sent to UE1, then it is preferable to designate UE2 as UE-TX and UE1 as UE-RX and apply the method described in this disclosure. Similar effects can be obtained.

[0506] The feedback information includes CSI report information transmitted from UE-RX (UE2) to UE-TX (UE1). By applying the method of this disclosure with UE2 as UE-TX and UE1 as UE-RX, the CSI report information may be sent and received within the PC5 DRX active period. This makes it possible to send and receive information that requires a larger amount of information, such as CSI report information.

[0507] If UE1 and UE2 are the UEs that communicate directly with each other using PC5, PC5 DRX settings may be applied to communication in both directions. When PC5 DRX is set for communication from UE1 to UE2, the transmitting UE is UE1 and the receiving UE is UE2. Therefore, it is appropriate to set UE1 as UE-TX and UE2 as UE-RX and apply the method described above as appropriate. When PC5 DRX is set for communication from UE2 to UE1, the transmitting UE is UE2 and the receiving UE is UE1. Therefore, it is appropriate to set UE2 as UE-TX and UE1 as UE-RX and apply the method described above as appropriate.

[0508] This document discloses a method for aligning (in other words, matching) the PC5 DRX settings in both directions during direct UE communication using PC5. As mentioned above, it is advisable to set the PC5 DRX settings in both directions so that, for example, both active periods are aligned (in other words, matched). Alternatively, it is advisable to set the PC5 DRX settings in both directions so that, for example, both active periods are continuous. Alternatively, even if both active periods are discontinuous, it is advisable to set the PC5 DRX settings in both directions so that the period from the start of one active period to the end of both active periods is minimized.

[0509] For example, it is a good idea to match the PC5 DRX settings for one direction to the PC5 DRX settings for the other direction. It is fine to configure the PC5 DRX settings for either direction first. For example, it is a good idea to configure the PC5 DRX settings for communication from UE1 to UE2, and then configure the PC5 DRX settings for communication from UE2 to UE1 to match the PC5 DRX settings for communication from UE1 to UE2. For example, one UE may configure the PC5 DRX settings for both directions to match. For example, a gNB connected to one UE may configure the PC5 DRX settings for both directions to match.

[0510] The previously configured PC5 DRX configuration information may be notified to the node that synchronizes the PC5 DRX configurations in both directions. This allows the node synchronizing the PC5 DRX configurations in both directions to use the previously configured PC5 DRX configuration to synchronize the PC5 DRX configurations in both directions, which can then be configured later.

[0511] By aligning the PC5 DRX settings in both directions, it becomes possible to reduce the power consumption of UEs that perform direct communication between UEs via PC5.

[0512] Figures 32 and 33 are sequence diagrams showing a first example of a method for aligning DRX in both directions during direct UE-to-UE communication at PC5 in Embodiment 4. Figures 32 and 33 are connected at the boundary line BL3233. Figures 32 and 33 show the case where UE1 is located in the OOC (Out Of Coverage) of the gNB and UE2 is located in the IC (In Coverage) of the gNB.

[0513] Since UE1 is OOC, in step ST2401, UE1 configures PC5 DRX settings for communication from UE1 to UE2. In step ST2402, UE1 notifies UE2 of the PC5 DRX configuration information. In step ST2403, UE2 configures the PC5 DRX settings received from UE1. In step ST2404, UE2 notifies that it has completed the PC5 DRX configuration for communication from UE1 to UE2. In this way, PC5 DRX configuration for communication from UE1 to UE2 becomes possible. As a result, in step ST2405, PC5 DRX processing is performed in SL communication. UE1 performs resource search, selection, and reservation for SL communication from UE1 to UE2, and uses the PC5 DRX processing to perform data communication.

[0514] UE2 decides to configure PC5 DRX for communication from UE2 to UE1. In step ST2406, UE2 notifies the connected gNB of the PC5 DRX configuration request for communication from UE2 to UE1. UE2 notifies the gNB of the SL traffic pattern for communication from UE2 to UE1. UE2 may also notify the gNB of service-related information for communication from UE2 to UE1 (e.g., service identifier, service type, service QoS, frequency of service data occurrence, etc.). This allows the gNB to derive the SL traffic pattern for communication from UE2 to UE1. UE2 also notifies the gNB of PC5 DRX configuration information from UE1 to UE2. UE2 may notify this information together with, or include in, the request information.

[0515] Upon receiving a PC5 DRX setting request from UE2 to UE1, the gNB, in step ST2407, uses this information to perform the PC5 DRX setting for communication from UE2 to UE1. The gNB sets the PC5 DRX setting for communication from UE2 to UE1 using the DRX setting from UE1 to UE2, so as to match the PC5 DRX settings in both directions. In this way, the gNB is able to match the PC5 DRX settings in both directions.

[0516] In step ST2408, gNB notifies UE2 of PC5 DRX configuration information. In step ST2409, UE2 performs the PC5 DRX configuration. Also, in step ST2410, UE2 notifies UE1 of the PC5 DRX configuration for communication from UE2 to UE1. In step ST2411, UE1 performs the PC5 DRX configuration. In step ST2412, UE1 notifies UE2 that the PC5 DRX configuration for communication from UE2 to UE1 is complete. This enables PC5 DRX processing for communication from UE2 to UE1.

[0517] In step ST2413, UE2 notifies gNB that the PC5 DRX configuration for communication from UE2 to UE1 is complete. UE2 may include scheduling request information for SL communication from UE2 to UE1 in the PC5 DRX configuration completion notification. Alternatively, UE2 may notify gNB of the SL communication scheduling request information separately from the PC5 DRX configuration completion notification. In step ST2414, gNB performs resource scheduling for communication from UE2 to UE1. In step ST2415, gNB notifies UE2 of the scheduling information for communication from UE2 to UE1. In step ST2416, UE2 performs data communication with UE1 using PC5 DRX processing.

[0518] By aligning the PC5 DRX settings in both directions during direct communication between UEs using PC5, it becomes possible to reduce the power consumption of UE1 and UE2, which are communicating directly between UEs using PC5.

[0519] Figures 34 and 35 are sequence diagrams showing a second example of a method for aligning DRX in both directions during direct communication between UEs at PC5 in Embodiment 4. Figures 34 and 35 are connected at the boundary line BL3435. Figures 34 and 35 show the case where UE1 is located on the IC of gNB1 and UE2 is located on the IC of gNB2. Since UE1 is an IC, gNB1 is the PC from UE1 to UE2.5 This section describes how to schedule communications.

[0520] UE1 decides to configure PC5 DRX for communication from UE1 to UE2. In step ST2501, UE1 notifies the connected gNB1 of the PC5 DRX configuration request for communication from UE1 to UE2. UE1 notifies gNB of the SL traffic pattern for communication from UE1 to UE2. UE1 may also notify gNB of service-related information for communication from UE1 to UE2 (e.g., service identifier, service type, service QoS, frequency of service data occurrence, etc.). This allows gNB1 to derive the SL traffic pattern for communication from UE1 to UE2.

[0521] Upon receiving a PC5 DRX configuration request from UE1 to UE2, gNB1 uses this information to configure the PC5 DRX settings for communication from UE1 to UE2 in step ST2502. In step ST2503, gNB1 notifies UE1 of the PC5 DRX configuration information. In step ST2504, UE1 configures the PC5 DRX settings. Also, in step ST2505, UE1 notifies UE2 of the PC5 DRX settings for communication from UE1 to UE2. In step ST2506, UE2 configures the PC5 DRX settings. In step ST2507, UE2 notifies UE1 that the PC5 DRX settings for communication from UE1 to UE2 have been completed. As a result, PC5 DRX processing becomes possible in communication from UE1 to UE2.

[0522] In step ST2508, UE1 notifies gNB1 that the PC5 DRX configuration for communication from UE1 to UE2 is complete. UE1 may include scheduling request information for SL communication from UE1 to UE2 in the PC5 DRX configuration completion notification. Alternatively, UE1 may notify gNB1 of the SL communication scheduling request information from UE1 to UE2 separately from the PC5 DRX configuration completion notification. In step ST2509, gNB1 performs resource scheduling for communication from UE1 to UE2. In step ST2510, gNB1 notifies UE1 of the scheduling information for communication from UE1 to UE2. In step ST2511, UE1 performs data communication with UE2 using PC5 DRX processing.

[0523] UE2 decides to configure PC5 DRX settings for communication from UE2 to UE1. After UE2 decides to configure PC5 DRX settings for communication from UE2 to UE1, the method for performing data communication with UE1 using PC5 DRX processing can be appropriately applied using the methods disclosed in Figures 32 and 33. Steps ST2406 to ST2416 in Figures 32 and 33 can be applied. Similar effects can be obtained.

[0524] In this way, even when both UE1 and UE2 are gNB ICs, it becomes possible to perform PC5 DRX processing with combined PC5 DRX settings in both directions during direct communication between UEs at PC5. This makes it possible to reduce the power consumption of UE1 and UE2 when they perform direct communication at PC5.

[0525] In communication between a remote UE and the network via a relay UE, PC5 DRX configuration is performed between the remote UE and the relay UE. PC5 DRX processing is carried out between the remote UE and the relay UE. In communication between a remote UE and the network via a relay UE, PC5 communication takes place between the remote UE and the relay UE. As a method for configuring PC5 DRX between the remote UE and the relay UE, the DRX configuration method for direct UE-to-UE communication using PC5, as described above, should be applied as appropriate.

[0526] For example, in SL communication from a remote UE to a relay UE, it is preferable to set the remote UE as UE-TX and the relay UE as UE-RX. Similarly, in SL communication from a relay UE to a remote UE, it is preferable to set the relay UE as UE-TX and the remote UE as UE-RX. For example, the Mode 2 method should be applied to a remote UE located in the OOC of a gNB. The Mode 1 method should be applied to a relay UE located in the IC of a gNB. By doing so, PC5 DRX configuration between the remote UE and the relay UE can be performed in communication between the remote UE and the network via the relay UE, and PC5 DRX processing can be performed between the remote UE and the relay UE. This reduces the power consumption of both the remote UE and the relay UE.

[0527] The PC5 DRX settings may be matched (or, in other words, aligned) in both directions: SL communication from the remote UE to the relay UE and SL communication from the relay UE to the remote UE. As a method for doing this, the method of matching the PC5 DRX settings in both directions in direct UE-to-UE communication via PC5, as described above, can be appropriately applied. For example, the methods disclosed in Figures 32 and 33 may be appropriately applied. In Figures 32 and 33, UE1, UE2, and gNB are assumed to be the remote UE, the relay UE, and the gNB connected to the relay UE, respectively. The gNB connected to the relay UE matches the PC5 DRX settings in both directions. By matching the PC5 DRX settings in both directions in this way, the power consumption of the remote UE and the relay UE can be further reduced.

[0528] In step ST2406 of Figures 32 and 33, UE2 notifies gNB of the SL traffic pattern from UE2 to UE1. When using a relay UE, the relay UE does not generate the service data that is communicated at PC5. Communication is performed from the NW to the remote UE. Therefore, the relay UE may not recognize the traffic pattern of communication to the remote UE. A method to solve this problem is disclosed.

[0529] The relay UE derives the traffic pattern from the relay UE to the remote UE in communication from the network to the remote UE. As a method of deriving this pattern, the relay UE may measure the data communication at PC5 from the relay UE to the remote UE. As a method of measurement, the method disclosed in Embodiment 1 may be applied as appropriate. Alternatively, the remote UE may notify the relay UE of the traffic pattern from the relay UE to the remote UE. The remote UE may derive the traffic pattern from the relay UE to the remote UE from information about services communicated with the network via the relay UE. Alternatively, the remote UE may measure the data communication at PC5 to the relay UE. In this way, the relay UE can recognize the traffic pattern of communication to the remote UE.

[0530] Alternatively, the gNB or UPF may derive the traffic pattern from the relay UE to the remote UE in the communication from the NW to the remote UE. The measurement method described above may be applied as appropriate. If the gNB derives the traffic pattern, the gNB may use the derivation result in step ST2407 in Figures 32 and 33. If the UPF derives the traffic pattern, the UPF may notify the gNB of the derived traffic pattern. The gNB may use the traffic pattern received from the UPF in step ST2407 in Figures 32 and 33. Similar effects can be obtained.

[0531] While the traffic patterns for communication from the network to the remote UE have been disclosed, the aforementioned methods may also be applied as appropriate to the traffic patterns for communication from the remote UE to the network.

[0532] This document discloses an alternative method for aligning (or synchronizing) the PC5 DRX settings in both directions: from the remote UE to the relay UE and from the relay UE to the remote UE. This method utilizes the fact that the remote UE is connected to the gNB via the relay UE to align the PC5 DRX settings in both directions. The gNB connected to the relay UE performs the PC5 DRX settings for communication from the remote UE to the relay UE. Alternatively, the gNB connected to the relay UE may perform the PC5 DRX settings in both directions between the remote UE and the relay UE.

[0533] The remote UE may request the gNB, via the relay UE, to configure PC5 DRX for communication from the remote UE to the relay UE. Alternatively, the relay UE may request the gNB to configure PC5 DRX for communication from the remote UE to the relay UE. Upon receiving the request, the gNB configures PC5 DRX for communication from the remote UE to the relay UE.

[0534] The remote UE may request the gNB, via the relay UE, to configure PC5 DRX in both directions between the remote UE and the relay UE. Alternatively, the relay UE may request the gNB to configure PC5 DRX in both directions between the remote UE and the relay UE. Upon receiving the request, the gNB configures PC5 DRX for bidirectional communication between the remote UE and the relay UE.

[0535] The gNB configures the bidirectional PC5 DRX settings to match the bidirectional PC5 DRX settings between the remote UE and the relay UE. This allows for further reduction in power consumption of both the remote UE and the relay UE.

[0536] Figures 36 and 37 are sequence diagrams illustrating an example of how to configure PC5 DRX settings between a remote UE and a relay UE in communication between the remote UE and the NW via a relay UE, according to Embodiment 4. Figures 36 and 37 are connected at the boundary line BL3637. Figures 36 and 37 show the case where the remote UE is located in the OOC of the gNB and the relay UE is located in the IC of the gNB. Figures 36 and 37 show the case where the remote UE requests the gNB to configure PC5 DRX settings for communication from the remote UE to the relay UE, and the relay UE requests the gNB to configure PC5 DRX settings for communication from the relay UE to the remote UE. Figures 36 and 37 show how a gNB connected to the relay UE configures bidirectional PC5 DRX settings to match the bidirectional PC5 DRX settings between the remote UE and the relay UE.

[0537] In step ST2601, the remote UE requests the gNB connected to the relay UE to configure PC5 DRX for communication from the remote UE to the relay UE. This request is notified via the relay UE. The remote UE may also notify the traffic pattern for communication from the remote UE to the NW along with the request, or include it in the request. In step ST2602, the gNB configures PC5 DRX for communication from the remote UE to the relay UE. In step ST2603, the gNB notifies the remote UE of the PC5 DRX configuration information for communication from the remote UE to the relay UE. This configuration information is notified via the relay UE. In step ST2604, the remote UE configures PC5 DRX for communication from the remote UE to the relay UE.

[0538] Furthermore, in step ST2605, the remote UE notifies the relay UE of the PC5 DRX configuration information for communication from the remote UE to the relay UE. In step ST2606, the relay UE performs the PC5 DRX configuration for communication from the remote UE to the relay UE. In step ST2607, the relay UE notifies the remote UE that the PC5 DRX configuration is complete. In this way, PC5 DRX configuration for communication from the remote UE to the relay UE becomes possible, and in step ST2608, PC5 DRX processing is performed in SL communication. The remote UE performs resource search, selection, and reservation for SL communication from the remote UE to the relay UE, and performs data communication using the PC5 DRX processing.

[0539] The PC5 DRX settings for communication from the relay UE to the remote UE are configured. The methods disclosed in Figures 32 and 33 can be applied as appropriate. UE1, UE2, and gNB in ​​Figures 32 and 33 can be replaced with the remote UE, relay UE, and gNB, respectively. Steps ST2406 to ST2416 in Figures 32 and 33 can be applied as appropriate to steps ST2609 to ST2619 in Figures 36 and 37. This allows the gNB to synchronize the PC5 DRX settings in both directions between the remote UE and the relay UE. This further reduces the power consumption of the remote UE and the relay UE.

[0540] In step ST2609, the relay UE does not need to notify the gNB of the PC5 DRX configuration information from the remote UE to the relay UE. The gNB is aware of the PC5 DRX configuration because it configured the PC5 DRX for communication from the remote UE to the relay UE in step ST2602. In step ST2610, the gNB should configure the PC5 DRX for communication from the relay UE to the remote UE using the PC5 DRX configuration for communication from the remote UE to the relay UE that was configured in step ST2602, so as to match the PC5 DRX configuration in both directions between the remote UE and the relay UE. A similar effect can be obtained.

[0541] This allows PC5 DRX settings to be configured between the remote UE and the relay UE, thereby reducing the power consumption of both the remote UE and the relay UE. Furthermore, it becomes possible to synchronize PC5 DRX settings in both directions between the remote UE and the relay UE, further reducing power consumption. This enables lower power consumption for both the relay UE and the remote UE during communication between the remote UE and the network via the relay UE.

[0542] Embodiment 5. This invention discloses another method for solving the problems described in Embodiment 1.

[0543] In communication between a remote UE and a network via a relay UE, the DRX setting between the relay UE and the network must be matched (in other words, aligned) with the PC5 DRX setting between the remote UE and the relay UE. The DRX setting between the relay UE and the network may be a paging DRX setting when the relay UE is in the RRC_Idle or RRC_Inactive state, or a C-DRX setting when the relay UE is in the RRC_Connected state. The PC5 DRX setting between the remote UE and the relay UE may be a bidirectional PC5 DRX setting between the remote UE and the relay UE.

[0544] The relay UE may configure both DRX settings so that the DRX setting between the relay UE and the network matches the PC5 DRX setting between the remote UE and the relay UE. The DL direction, i.e., the DRX setting from the network to the relay UE, may be matched with the PC5 DRX setting from the relay UE to the remote UE. The UL direction, i.e., the PC5 DRX setting from the remote UE to the relay UE, may be matched with the DRX setting from the relay UE to the network. The DRX settings in both the DL and UL directions may be matched with the PC5 DRX setting.

[0545] As a method for matching the DRX settings between the relay UE and the NW with the PC5 DRX settings between the remote UE and the relay UE, the methods disclosed in Embodiments 1 to 4 may be applied as appropriate.

[0546] For example, the remote UE configures both DRX settings so that the DRX settings between the relay UE and the network match the PC5 DRX settings between the remote UE and the relay UE. The remote UE configures the PC5 DRX settings for communication between the remote UE and the relay UE. The remote UE configures the PC5 DRX settings for communication from the remote UE to the relay UE. The remote UE may also configure the PC5 DRX settings for communication from the relay UE to the remote UE. The method disclosed in Embodiment 4 is applied as appropriate. and good.

[0547] The remote UE uses the PC5 DRX settings between it and the relay UE to configure the DRX settings between the relay UE and the network so that the DRX settings between the relay UE and the network match the PC5 DRX settings between the remote UE and the relay UE. The remote UE may also determine DRX-related information, including DRX settings. For example, specific examples of DRX-related information include the paging DRX settings requested from the relay UE, the C-DRX settings requested from the relay UE, or the traffic patterns between the remote UE and the network. The DRX-related information may be a combination of these.

[0548] The remote UE notifies the NW via the relay UE of DRX-related information between the relay UE and the NW. The NW node, for example, a gNB or AMF, uses this DRX-related information to configure the DRX settings between the relay UE and the NW. As such methods, the methods disclosed in Modification 1 of Embodiments 1 to 3 may be applied as appropriate.

[0549] In this way, in communication between the remote UE and the network via the relay UE, it becomes possible to match the DRX settings between the relay UE and the network with the PC5 DRX settings between the remote UE and the relay UE. Since the remote UE is aware of the service of communication between the remote UE and the network, for example, the remote UE can perform the PC5 DRX settings and the DRX settings between the relay UE and the network based on the information it is aware of. This makes it possible to perform PC5 DRX settings and DRX settings that are suitable for the service of communication between the remote UE and the network.

[0550] For example, the relay UE may configure both DRX settings so that the DRX setting between the relay UE and the NW matches the PC5 DRX setting between the remote UE and the relay UE. The relay UE configures the PC5 DRX setting for communication between the remote UE and the relay UE. The method disclosed in Embodiment 4 may be applied as appropriate.

[0551] The relay UE uses the PC5 DRX settings with the remote UE to configure the DRX settings between the relay UE and the network so that the DRX settings between the relay UE and the network match the PC5 DRX settings between the remote UE and the relay UE. The relay UE notifies the network of the DRX-related information between the relay UE and the network. The network node, for example, a gNB or AMF, uses this DRX-related information to configure the DRX settings between the relay UE and the network. As these methods, the methods disclosed in Modification 1 of Embodiments 1 to 3 may be applied as appropriate.

[0552] In this way, in communication between a remote UE and a network via a relay UE, it becomes possible to match the DRX settings between the relay UE and the network with the PC5 DRX settings between the remote UE and the relay UE. Furthermore, by having the relay UE configure the settings, even when multiple remote UEs are connected to the relay UE, it becomes possible to configure PC5 DRX settings and DRX settings that are suitable for the data generation patterns in communication between multiple remote UEs and the relay UE.

[0553] For example, the gNB may configure both DRX settings so that the DRX setting between the relay UE and the NW matches the PC5 DRX setting between the remote UE and the relay UE. The gNB connected to the relay UE configures the PC5 DRX setting for communication between the remote UE and the relay UE. The method disclosed in Embodiment 4 may be applied as appropriate.

[0554] The gNB uses the PC5 DRX settings with the remote UE to configure the DRX settings between the relay UE and the network so that the DRX settings between the relay UE and the network match the PC5 DRX settings between the remote UE and the relay UE. The gNB may also notify the network of DRX-related information between the relay UE and the network. The network node, for example, the AMF, uses this DRX-related information to configure the DRX settings between the relay UE and the network. As these methods, the methods disclosed in Modification 1 of Embodiments 1 to 3 may be applied as appropriate.

[0555] In this way, it becomes possible to match the DRX settings between the relay UE and the network with the PC5 DRX settings between the remote UE and the relay UE in communication between the remote UE and the network via the relay UE. Furthermore, by configuring the settings, the gNB can recognize the communication status of all relay UEs connected to the gNB and all remote UEs connected to the relay UEs. As a result, the system can perform more appropriate PC5 DRX and DRX settings in communication between the remote UE and the network via the gNB.

[0556] By doing this, it becomes possible to match the DRX settings between the relay UE and the network with the PC5 DRX settings between the remote UE and the relay UE in communication between the remote UE and the network via the relay UE. As a result, the power consumption of the remote UE and the relay UE can be further reduced.

[0557] If a remote UE connects to a gNB via a relay UE, the gNB may perform scheduling for PC5-based communication between the remote UE and other UEs. The remote UE may notify the relay UE of information regarding the PC5-based communication service with other UEs. The gNB uses this information to schedule PC5-based communication for the remote UE. The gNB then notifies the remote UE of this scheduling information via the relay UE. . The mote UE communicates with other UEs using PC5 according to the scheduling information received from the gNB via the relay UE.

[0558] A remote UE may notify the gNB of a Scheduling Request (SR) via a relay UE. The gNB may perform scheduling for the remote UE based on the SR received from the remote UE via the relay UE. A remote UE may notify the gNB of a Buffer Status Report (BSR) via a relay UE. The gNB may perform scheduling for the remote UE based on the BSR received from the remote UE via the relay UE.

[0559] A PUCCH may be provided for transmitting the remote UE's SR from the relay UE to the gNB. The gNB is a relay UE Alternatively, a PUSCH can be configured for transmitting SRs from the remote UE. Another method is to use a PUSCH for transmitting SRs from the remote UE to the gNB. The relay UE may include the remote UE's SR in the PUSCH and notify the gNB. Another method is to use MAC signaling for transmitting SRs from the remote UE to the gNB. It may be configured as MAC CE. Another method is to use RRC signaling for transmitting SRs from the remote UE to the gNB. This allows for the notification of a larger amount of information.

[0560] The aforementioned method should also be applied appropriately to the transmission of the BSR from the relay UE to the gNB by the remote UE.

[0561] In this way, even if a remote UE is outside the gNB's coverage, if it connects to the gNB via a relay UE, it becomes possible to obtain scheduling information for PC5-based communication from the gNB. By enabling the scheduling of PC5-based communication between the remote UE connected to the relay UE by the gNB and other UEs, for example, it becomes possible to reduce resource conflicts used for these communications. This makes it possible to improve the efficiency of resource utilization.

[0562] In communication between a remote UE and a network via a relay UE, the resource timing of the computer graphics (CG) set between the gNB and the relay UE may be matched with the resource timing of the CG set between the remote UE and the relay UE. For example, the gNB may schedule the remote UE via the relay UE, and the gNB will match the resource timing of the CG at the Uu set for the relay UE with the resource timing of the CG at PC5 set for the remote UE. The gNB may also set the resource timings of both to fall within a predetermined period. By doing so, the power consumption of the remote UE and the relay UE can be further reduced.

[0563] In this disclosure, the UE from which the service data originates is designated as UE-TX. For example, if UE-TX is UE1 and UE-RX is UE2, and service data originates in UE2 and is sent to UE1, then it is preferable to designate UE2 as UE-TX and UE1 as UE-RX and apply the method described in this disclosure. Similar effects can be obtained.

[0564] The embodiments and their variations described above are merely illustrative, and these embodiments and their variations can be freely combined. Furthermore, any component of each embodiment and its variations can be modified or omitted as appropriate.

[0565] For example, in the embodiments and their modifications described above, 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 embodiments and their modifications described above, the processing described as being performed in subframe units may also be performed in TTI units, slot units, sub-slot units, or mini-slot units.

[0566] For example, the methods disclosed in each of the embodiments and their variations described above may be applied not only to V2X (Vehicle-to-everything) services but also to services that use SL communication. For example, they may be applied to SL communication used in various services such as proximity-based services, public safety, communication between wearable devices, and communication between machines in factories.

[0567] Although this disclosure has been described in detail, the above description is illustrative and not limiting in all respects. It is understood that countless variations not illustrated are conceivable. [Explanation of Symbols]

[0568] 200, 210 Communication systems, 202 Communication terminal equipment (communication terminals), 203, 207, 213, 217, 223-1, 224-1, 224-2, 226-1, 226-2 Base station equipment (base stations), 204, 214 Management equipment.

Claims

1. A first terminal device in a communication system, The communication system comprises a plurality of terminal devices that perform unicast communication in sidelink communication via a PC5 interface, and includes a first terminal device which is a transmitting terminal device and a second terminal device which is a receiving terminal device. The first terminal device is configured to determine the DRX (Discontinuous reception) setting for the receiving operation of the second terminal device in the unicast communication, and to transmit the DRX setting to the second terminal device. The DRX setting includes information relating to a first period from the transmission of a HARQ (hybrid automatic repeat request) feedback signal from the second terminal device to retransmission by the first terminal device, and information relating to a second period for retransmission set after the first period. The first terminal device.

2. The first terminal device is configured to transmit the DRX settings to the second terminal device using PC5-RRC (Radio Resource Control) signaling for AS (Access Stratum) settings. The first terminal device according to claim 1.

3. The DRX setting includes information regarding the DRX period and information regarding an offset for determining the start timing of the DRX period. The first terminal device according to claim 1.

4. The aforementioned DRX settings are: Information regarding the on-time interval, Information regarding the in-activity period, including, The first terminal device according to claim 1.

5. The ON interval, the in-activity period, the first period, and the second period are each set by a timer. The first terminal device according to claim 4.

6. A second terminal device in a communication system, The communication system comprises a plurality of terminal devices that perform unicast communication in sidelink communication via a PC5 interface, and includes a first terminal device which is a transmitting terminal device and a second terminal device which is a receiving terminal device. The second terminal device is configured to receive a DRX (Discontinuous reception) setting for the receiving operation of the second terminal device in the unicast communication from the first terminal device, and to perform the receiving operation according to the DRX setting. The DRX setting includes information relating to a first period from the transmission of a HARQ (hybrid automatic repeat request) feedback signal from the second terminal device to retransmission by the first terminal device, and information relating to a second period for retransmission set after the first period. The second terminal device.

7. A communication system comprising multiple terminal devices that perform unicast communication in sidelink communication via a PC5 interface, the system including a first terminal device which is a transmitting terminal device and a second terminal device which is a receiving terminal device, The first terminal device is configured to determine the DRX (Discontinuous reception) setting for the receiving operation of the second terminal device in the unicast communication, and to transmit the DRX setting to the second terminal device. The DRX setting includes information relating to a first period from the transmission of a HARQ (hybrid automatic repeat request) feedback signal from the second terminal device to retransmission by the first terminal device, and information relating to a second period for retransmission set after the first period. Communication system.

Images