Terminal device, method, and integrated circuit

Abstract

This terminal device, which communicates with a base station device via a relay terminal device, receives a first discovery message, and transmits a second discovery message upon determining that the RRC state of the terminal device is RRC_CONNECTED, wherein the first discovery message and the second discovery message are messages transmitted using SL-SRB4.

Description

Terminal device, method, and integrated circuit

[0001] This application claims priority from Japanese Patent Application No. 2024-131153, filed on August 7, 2024, the contents of which are incorporated herein by reference.

[0002] The 3rd Generation Partnership Project (3GPP [registered trademark]), a standardization project for cellular mobile communication systems, is conducting technical studies and formulating standards for cellular mobile communication systems, including radio access, core networks, services, etc.

[0003] For example, 3GPP has begun technical studies and standardization of E-UTRA (Evolved Universal Terrestrial Radio Access) as a radio access technology (RAT) for 3.9G and 4G cellular mobile communication systems. 3GPP is currently conducting technical studies and standardization of E-UTRA extension technologies. E-UTRA is also called Long Term Evolution (LTE: registered trademark), and the extension technologies are sometimes called LTE-Advanced (LTE-A) and LTE-Advanced Pro (LTE-A Pro).

[0004] Additionally, 3GPP has begun technical studies and standardization of NR (New Radio, or NR Radio access) as a radio access technology (RAT) for 5th Generation (5G) cellular mobile communication systems. 3GPP is currently conducting technical studies and standardization of NR extension technologies.

[0005] 3GPP TS 38.331 v18.2.0, "NR; Radio Resource Control (RRC) protocol specification" pp90-108,pp372-450, pp1493-15163GPP TS 38.300 v18.2.0, "NR; NR and NG-RAN Overall Description" pp50-52,pp166-176, pp187-207

[0006] 3GPP has been studying a technology called sidelink (SL), which allows terminal devices to communicate directly with each other without going through the core network, as an extension technology of NR. It has also studied a technology called UE-to-Network Relay (U2N Relay), in which a relay terminal device provides communication via sidelink, allowing terminal devices to communicate with a base station device via the relay terminal device, and has enhanced service continuity in U2N Relay. Furthermore, it has begun studying multi-hop relay, which connects multiple relay terminal devices to enhance connectivity to remote terminal devices.

[0007] One aspect of the present invention has been made in consideration of the above-mentioned circumstances, and one of its objects is to provide a terminal device, a base station device, a method, and an integrated circuit that can efficiently perform communication control.

[0008] In order to achieve the above object, one aspect of the present invention takes the following measures.

[0009] (1) A first aspect of the present invention is a terminal device that communicates with a base station device via a relay terminal device, comprising a receiving unit that receives a first discovery message and a processing unit, wherein the processing unit transmits a second discovery message based on determining that the RRC state of the terminal device is RRC_CONNECTED, and the first discovery message and the second discovery message are messages transmitted via SL-SRB4.

[0010] (2) A second aspect of the present invention is a method for a terminal device to communicate with a base station device via a relay terminal device, comprising the steps of receiving a first discovery message and transmitting a second discovery message based on determining that the RRC state of the terminal device is RRC_CONNECTED, wherein the first discovery message and the second discovery message are messages transmitted via SL-SRB4.

[0011] (3) A third aspect of the present invention is an integrated circuit implemented in a terminal device that communicates with a base station device via a relay terminal device, and has a function of receiving a first discovery message and a function of transmitting a second discovery message based on determining that the RRC state of the terminal device is RRC_CONNECTED, wherein the first discovery message and the second discovery message are messages transmitted via SL-SRB4.

[0012] These comprehensive or specific aspects may be realized as a system, an apparatus, a method, an integrated circuit, a computer program, or a recording medium, or may be realized as any combination of a system, an apparatus, a method, an integrated circuit, a computer program, and a recording medium.

[0013] According to one aspect of the present invention, it is possible to provide a terminal device, a base station device, and a method for realizing efficient communication control processing.

[0014] 1. A schematic diagram of a communication system according to the present embodiment. 2. A diagram of an example of a protocol configuration in NR sidelink communication according to the present embodiment. 3. A diagram of an example of a protocol configuration in NR sidelink communication according to the present embodiment. 4. A diagram of an example of a protocol configuration in a discovery procedure according to the present embodiment. 5. A block diagram showing the configuration of a terminal device according to the present embodiment. 6. A block diagram showing the configuration of a base station device according to the present embodiment. 7. A diagram of an example of a protocol configuration in NR according to the present embodiment. 8. A diagram of an example of a protocol configuration of a control plane of an L2 U2N relay according to the present embodiment. 9. A diagram of an example of a protocol configuration of a user plane of an L2 U2N relay according to the present embodiment. 10. An example of a process according to the present embodiment. 11. A diagram of an example of a protocol configuration of a control plane of a multi-hop L2 U2N relay according to the present embodiment.

[0015] Hereinafter, this embodiment will be described in detail with reference to the drawings.

[0016] In this embodiment, the names of the nodes and entities and the processes in the nodes and entities when the radio access technology is NR will be described, but this embodiment may be applied to other radio access technologies. The names of the nodes and entities in this embodiment may be different names.

[0017] Fig. 1 is a schematic diagram of a communication system according to this embodiment. Note that the functions of each node, radio access technology, core network, interface, etc. described using Fig. 1 are only some of the functions closely related to this embodiment, and the system may have other functions.

[0018] E-UTRA may be a radio access technology. E-UTRA may also be the air interface between the UE 122 and the ng-eNB 100. The air interface 112 between the UE 122 and the ng-eNB 100 may be referred to as the Uu interface. The ng-eNB (ng E-UTRAN Node B) 100 may be an E-UTRAN base station device. The ng-eNB 100 may have the E-UTRA protocol described below. The E-UTRA protocol may be composed of the E-UTRA User Plane (UP) protocol described below and the E-UTRA Control Plane (CP) protocol described below. The ng-eNB 100 may terminate the E-UTRA user plane protocol and the E-UTRA control plane protocol for the UE 122. A radio access network composed of eNBs may be referred to as E-UTRAN.

[0019] NR may be a radio access technology. NR may also be an air interface between the UE 122 and the gNB 102. The air interface 112 between the UE 122 and the gNB 102 may be referred to as a Uu interface. The gNB (g Node B) 102 may be an NR base station device. The gNB 102 may have the NR protocol described below. The NR protocol may be composed of an NR user plane (User Plane: UP) protocol described below and an NR control plane (Control Plane: CP) protocol described below. The gNB 102 may terminate the NR user plane protocol and the NR control plane protocol for the UE 122.

[0020] The interface 110 between the ng-eNB 100 and the gNB 102 may be referred to as an Xn interface. The ng-eNB and the gNB may connect to the 5GC via an interface called an NG interface (not shown). The 5GC may be a core network. One or more base station devices may connect to the 5GC via the NG interface.

[0021] A state in which a base station device can be connected to only via the Uu interface may be referred to as Inside NG-RAN Coverage or In-Coverage (IC). A state in which a base station device cannot be connected to only via the Uu interface may be referred to as Outside NG-RAN Coverage or Out-of-Coverage (OoC). The air interface 114 between UEs 122 may be referred to as a PC5 interface. Communication between UEs 122 via the PC5 interface may be referred to as sidelink (SL) communication. A terminal device capable of sidelink communication may be referred to as a sidelink communication-capable terminal device.

[0022] In the following description, the ng-eNB 100 and / or the gNB 102 will also be referred to simply as a base station device, and the UE 122 will also be referred to simply as a terminal device or a UE. The PC5 interface will also be referred to simply as PC5, and the Uu interface will also be referred to simply as Uu.

[0023] Sidelink is a technology that enables direct communication between terminal devices via PC5, and sidelink transmission and reception on PC5 is performed inside and outside the NG-RAN coverage.

[0024] There are three transmission modes for NR SL communication, and SL communication is performed in one of the transmission modes by a pair of a source Layer-2 (L2) ID and a destination Layer-2 (L2) ID. The source Layer-2 ID and the destination Layer-2 ID may be referred to as a source L2 ID and a destination L2 ID, respectively. The three transmission modes are "unicast transmission," "groupcast transmission," and "broadcast transmission." Note that the transmission modes may also be referred to as "cast type," etc. Note that unicast transmission for direct communication is supported on PC5, and a PC5 unicast link between two UEs may be established for direct communication. Furthermore, the PC5 unicast link may be maintained, changed, or released according to application layer requests or communication requirements.

[0025] Unicast transmission is characterized by (1) support for one PC5-RRC connection between a paired UE, (2) transmission and reception of control information and user traffic between UEs on the sidelink, (3) support for sidelink HARQ feedback, (4) transmit power control on the sidelink, (5) support for RLC AM, and (6) radio link failure detection for the PC5-RRC connection.

[0026] Groupcast transmission is characterized by (1) transmitting and receiving user traffic between UEs belonging to a sidelink group, and (2) supporting sidelink HARQ feedback.

[0027] Broadcast transmission is also characterized as (1) transmission and reception of user traffic between UEs on the sidelink.

[0028] 2 and 3 are diagrams illustrating an example of a protocol architecture for NR sidelink communication according to this embodiment. Note that the functions of each protocol described using FIG. 2 and / or FIG. 3 are only some of the functions closely related to this embodiment, and other functions may also be included. Note that in this embodiment, a sidelink (SL) may be a link between terminal devices.

[0029] 2A is a diagram of a protocol stack of a control plane (CP) for an SCCH using RRC configured on a PC5 interface. As shown in FIG. 2A, the control plane protocol stack for an SCCH using RRC may be configured with a PHY (Physical layer) 200, which is a radio physical layer, a MAC (Medium Access Control) 202, which is a medium access control layer, a RLC (Radio Link Control) 204, which is a radio link control layer, a PDCP (Packet Data Convergence Protocol) 206, which is a packet data convergence protocol layer, and an RRC (Radio Resource Control) 208, which is a radio resource control layer. Also, FIG. 2B is a diagram of a protocol stack of a control plane for an SCCH using PC5-S configured on a PC5 interface. As shown in FIG. 2(B), the control plane protocol stack for SCCH using PC5-S may be composed of PHY (Physical layer) 200, which is a wireless physical layer, MAC (Medium Access Control) 202, which is a medium access control layer, RLC (Radio Link Control) 204, which is a radio link control layer, PDCP (Packet Data Convergence Protocol) 206, which is a packet data convergence protocol layer, and PC5-S (PC5 Signalling) 210, which is a PC5 signaling layer.

[0030] Figure 3(A) is a diagram of a protocol stack of a control plane for SBCCH configured on a PC5 interface. As shown in Figure 3(A), the control plane protocol stack for SBCCH may be configured with a PHY (Physical layer) 200, which is a radio physical layer, a MAC (Medium Access Control) 202, which is a medium access control layer, a RLC (Radio Link Control) 204, which is a radio link control layer, and an RRC (Radio Resource Control) 208, which is a radio resource control layer. Figure 3(B) is a diagram of a protocol stack of a user plane (UP) for STCH configured on a PC5 interface. As shown in FIG. 3(B), the control plane protocol stack for the STCH may be composed of a PHY (Physical layer) 200, which is a radio physical layer, a MAC (Medium Access Control) 202, which is a medium access control layer, a RLC (Radio Link Control) 204, which is a radio link control layer, a PDCP (Packet Data Convergence Protocol) 206, which is a packet data convergence protocol layer, and an SDAP (Service Data Adaptation Protocol) 310, which is a service data adaptation protocol layer.

[0031] The AS (Access Stratum) layer may be a layer including some or all of the PHY 200, MAC 202, RLC 204, PDCP 206, SDAP 310, and RRC 208. The PC5-S 210 and Discovery 400 described later may be layers higher than the AS layer.

[0032] In this embodiment, the terms PHY (PHY layer), MAC (MAC layer), RLC (RLC layer), PDCP (PDCP layer), SDAP (SDAP layer), RRC (RRC layer), and PC5-S (PC5-S layer) may be used. In this case, PHY (PHY layer), MAC (MAC layer), RLC (RLC layer), PDCP (PDCP layer), SDAP (SDAP layer), RRC (RRC layer), and PC5-S (PC5-S layer) may respectively refer to the PHY (PHY layer), MAC (MAC layer), RLC (RLC layer), PDCP (PDCP layer), SDAP (SDAP layer), RRC (RRC layer), and PC5-S (PC5-S layer) of the NR sidelink protocol. Note that when sidelink communication is performed using E-UTRA technology, the SDAP layer may not be required. To clarify that it is a protocol for sidelink, for example, RLC may be expressed as sidelink RLC, and for other protocols, the term "sidelink," "SL," or "PC5" may be added to the beginning to indicate that it is a protocol for sidelink.

[0033] In addition, in this embodiment, when distinguishing between E-UTRA protocols and NR protocols, PHY, MAC, RLC, PDCP, and RRC may be referred to as E-UTRA PHY or LTE PHY, E-UTRA MAC or LTE MAC, E-UTRA RLC or LTE RLC, E-UTRA PDCP or LTE PDCP, and E-UTRA RRC or LTE RRC, respectively. PHY, MAC, RLC, PDCP, and RRC may also be referred to as E-UTRA PHY or LTE PHY, E-UTRA MAC or LTE MAC, E-UTRA RLC or LTE RLC, E-UTRA PDCP or LTE PDCP, and E-UTRA RRC or LTE RRC, respectively. When distinguishing between E-UTRA protocols, sidelink protocols, and NR protocols, PHY, MAC, RLC, PDCP, and RRC may also be referred to as NR PHY, NR MAC, NR RLC, NR RLC, and NR RRC, respectively. PHY, MAC, RLC, PDCP, and RRC may also be referred to as NR PHY, NR MAC, NR RLC, NR PDCP, and NR RRC, respectively.

[0034] This section describes entities in the AS layer of E-UTRA, NR, and / or sidelink. An entity having some or all of the physical layer functions may be referred to as a PHY entity. An entity having some or all of the MAC layer functions may be referred to as a MAC entity. An entity having some or all of the RLC layer functions may be referred to as an RLC entity. An entity having some or all of the PDCP layer functions may be referred to as a PDCP entity. An entity having some or all of the SDAP layer functions may be referred to as an SDAP entity. An entity having some or all of the RRC layer functions may be referred to as an RRC entity. The PHY entity, MAC entity, RLC entity, PDCP entity, SDAP entity, and RRC entity may be referred to as PHY, MAC, RLC, PDCP, SDAP, and RRC, respectively. Furthermore, each entity in the AS layer may be a common entity for E-UTRA, NR, and / or sidelink, or may be an independent entity.

[0035] Note that data provided from MAC, RLC, PDCP, and SDAP to lower layers, and / or data provided from lower layers to MAC, RLC, PDCP, and SDAP, may be referred to as MAC PDU (Protocol Data Unit), RLC PDU, PDCP PDU, and SDAP PDU, respectively. Data provided from higher layers to MAC, RLC, PDCP, and SDAP, and / or data provided from MAC, RLC, PDCP, and SDAP to higher layers, may be referred to as MAC SDU (Service Data Unit), RLC SDU, PDCP SDU, and SDAP SDU, respectively. A segmented RLC SDU may be referred to as an RLC SDU segment.

[0036] Here, the base station apparatus and the terminal apparatus exchange (transmit and receive) signals in a higher layer on the Uu interface. The higher layer may be referred to as the upper layer, and the terms may be interchangeable. For example, the base station apparatus and the terminal apparatus may transmit and receive RRC messages (also referred to as RRC signaling) in a Radio Resource Control (RRC) layer. Furthermore, the base station apparatus and the terminal apparatus may transmit and receive MAC Control Elements (MAC CEs) in a Medium Access Control (MAC) layer. Furthermore, the RRC layer of the terminal apparatus acquires system information broadcast from the base station apparatus. Here, the RRC messages, system information, and / or MAC control elements are also referred to as higher layer signals (higher layer signaling) or higher layer parameters (higher layer parameters). Each of the parameters included in the higher layer signals received by the terminal apparatus may be referred to as a higher layer parameter. For example, in PHY layer processing, an upper layer means a layer higher than the PHY layer, and therefore may mean one or more of a MAC layer, an RRC layer, an RLC layer, a PDCP layer, an NAS (Non Access Stratum) layer, etc. For example, in MAC layer processing, an upper layer may mean one or more of an RRC layer, an RLC layer, a PDCP layer, an NAS layer, etc.

[0037] Furthermore, terminal devices also exchange (transmit and receive) signals in higher layers on the PC5 interface. Terminal devices may transmit and receive RRC messages (also referred to as RRC signaling) in the Radio Resource Control (RRC) layer. Terminal devices may also transmit and receive MAC Control Elements (MAC CEs) in the Medium Access Control (MAC) layer. Here, RRC messages and / or MAC control elements are also referred to as higher layer signals (higher layer signaling) or higher layer parameters (higher layer parameters). Each of the parameters included in higher layer signals received by a terminal device may be referred to as a higher layer parameter. For example, in PHY layer processing, the higher layer refers to a layer higher than the PHY layer, and may therefore refer to one or more of the MAC layer, RRC layer, RLC layer, PDCP layer, PC5-S layer, Discovery layer, etc. For example, in MAC layer processing, the upper layer may refer to one or more of the RRC layer, RLC layer, PDCP layer, PC5-S layer, Discovery layer, etc.

[0038] Hereinafter, the meaning of "A is given (provided) by an upper layer" or "A is given (provided) by an upper layer" may mean that an upper layer (mainly an RRC layer, a MAC layer, etc.) of a terminal device receives A from a base station device or another terminal device, and the received A is given (provided) to a physical layer of the terminal device from the upper layer of the terminal device. For example, in a terminal device, "being provided with an upper layer parameter" may mean receiving an upper layer signal from a base station device or another terminal device, and providing an upper layer parameter included in the received upper layer signal from the upper layer of the terminal device to the physical layer of the terminal device. Setting an upper layer parameter in a terminal device may mean that the upper layer parameter is given (provided) to the terminal device. For example, setting an upper layer parameter in a terminal device may mean that the terminal device receives an upper layer signal from a base station device or another terminal device, and setting the received upper layer parameter in the upper layer. However, setting an upper layer parameter in a terminal device may include setting a default parameter that is given in advance to an upper layer of the terminal device. When describing transmission of an RRC message from a terminal device to a base station device or another terminal device, the expression "submitting a message from the RRC entity of the terminal device to a lower layer" may be used. In the terminal device, "submitting a message to a lower layer" from the RRC entity may mean submitting a message to the PDCP layer. In the terminal device, "submitting a message to a lower layer" from the RRC layer may mean submitting to a PDCP entity corresponding to each SRB, since RRC messages are transmitted using SRBs (SRB0, SRB1, SRB2, SRB3, etc.). When the RRC entity of the terminal device receives an indication from a lower layer, the lower layer may mean one or more of the PHY layer, MAC layer, RLC layer, PDCP layer, etc.

[0039] An example of the function of the PHY will be described. The PHY of a terminal device may have a function of transmitting and receiving data transmitted via a sidelink (SL) physical channel with the PHY of another terminal device. The PHY may be connected to a higher MAC via a transport channel. The PHY may pass data to the MAC via the transport channel. The PHY may also receive data from the MAC via the transport channel. In the PHY, a Radio Network Temporary Identifier (RNTI) may be used to identify various control information.

[0040] Here, the physical channels will be described. The physical channels used for wireless communication between a terminal device and another terminal device may include the following physical channels.

[0041] PSBCH (Physical Sidelink Broadcast CHannel) PSCCH (Physical Sidelink Control CHannel) PSSCH (Physical Sidelink Shared CHannel) PSFCH (Physical Sidelink Feedback CHannel)

[0042] The PSBCH may be used to broadcast system information required by the terminal device.

[0043] The PSCCH may be used to indicate resources and other transmission parameters for the PSSCH.

[0044] The PSSCH may be used to transmit data and control information related to HARQ / CSI feedback to other terminal devices.

[0045] The PSFCH may be used to carry HARQ feedback to other terminal devices.

[0046] An example of the MAC function will be described. The MAC may be referred to as a MAC sublayer. The MAC may have the function of mapping various logical channels to corresponding transport channels. A logical channel may be identified by a logical channel identity (or logical channel ID). The MAC may be connected to the higher-level RLC via a logical channel. Depending on the type of information to be transmitted, the logical channel may be divided into a control channel for transmitting control information and a traffic channel for transmitting user information. The MAC may have the function of multiplexing MAC SDUs belonging to one or more different logical channels and providing them to the PHY. The MAC may also have the function of demultiplexing MAC PDUs provided by the PHY and providing them to the higher layer via the logical channel to which each MAC SDU belongs. The MAC may also have the function of performing error correction through HARQ (Hybrid Automatic Repeat reQuest). The MAC may also have the function of reporting scheduling information. The MAC may have the function of prioritizing between terminal devices using dynamic scheduling. The MAC may also have the function of prioritizing between logical channels within one terminal device. The MAC may have the function of prioritizing overlapping resources within one terminal device. The E-UTRA MAC may have the function of identifying Multimedia Broadcast Multicast Services (MBMS). The NR MAC may have the function of identifying Multicast / Broadcast Services (MBS). The MAC may have the function of selecting a transport format.The MAC may have functions such as discontinuous reception (DRX) and / or discontinuous transmission (DTX), a random access (RA) procedure, a power headroom report (PHR) function that notifies information about available transmission power, and a buffer status report (BSR) function that notifies information about the amount of data in the transmission buffer. The NR MAC may have a bandwidth adaptation (BA) function. The MAC PDU format used in the E-UTRA MAC may differ from that used in the NR MAC. The MAC PDU may also include a MAC control element (MAC CE), which is an element for controlling the MAC.

[0047] In addition, the MAC sublayer may provide additional services and functions over the PC5 interface, such as radio resource selection for selecting radio resources for sidelink transmission, filtering of packets received in sidelink communication, priority processing between uplink and sidelink, and reporting of sidelink channel state information (Sidelink CSI).

[0048] This section describes the sidelink (SL) logical channels used in E-UTRA and / or NR, and the mapping between the sidelink logical channels and transport channels.

[0049] The SBCCH (Sidelink Broadcast Control Channel) may be a logical channel for sidelink broadcasting sidelink system information from one terminal device to one or more terminal devices, and may be mapped to the SL-BCH, which is a sidelink transport channel.

[0050] The SCCH (Sidelink Control Channel) may be a sidelink logical channel for transmitting control information such as a PC5-RRC message or a PC5-S message from one terminal device to one or more terminal devices. The SCCH may also be mapped to the SL-SCH, which is a sidelink transport channel.

[0051] The STCH (Sidelink Traffic Control Channel) may be a sidelink logical channel for transmitting user information from one terminal device to one or more terminal devices, and may be mapped to the SL-SCH, which is a sidelink transport channel.

[0052] An example of the RLC function will be described. The RLC may also be called an RLC sublayer. The E-UTRA RLC may have the function of segmenting and / or concatenating data provided by the PDCP in the upper layer and providing it to the lower layer. The E-UTRA RLC may have the function of reassembling and reordering data provided by the lower layer and providing it to the upper layer. The NR RLC may have the function of adding a sequence number independent of the sequence number added by PDCP to data provided by the PDCP in the upper layer. The NR RLC may also have the function of segmenting data provided by PDCP and providing it to the lower layer. The NR RLC may also have the function of reassembling data provided by the lower layer and providing it to the upper layer. The RLC may also have the function of data retransmission and / or retransmission request (Automatic Repeat reQuest: ARQ). RLC may also have the function of performing error correction using ARQ. The control information sent from the receiving side of RLC to the transmitting side to indicate data that needs to be retransmitted in order to perform ARQ may be called a status report. The status report transmission instruction sent from the transmitting side of RLC to the receiving side may be called a poll. RLC may also have the function of detecting data duplication. RLC may also have the function of discarding data. RLC may have three modes: transparent mode (TM), unacknowledged mode (UM), and acknowledged mode (AM). In TM, data received from the upper layer is not segmented, and an RLC header does not need to be added. The TM RLC entity is a unidirectional entity and may be configured as a transmitting TM RLC entity or a receiving TM RLC entity.In UM, the UM RLC entity performs functions such as segmenting and / or concatenating data received from a higher layer and adding an RLC header, but does not require data retransmission control. The UM RLC entity may be a unidirectional or bidirectional entity. If the UM RLC entity is a unidirectional entity, it may be configured as a transmitting UM RLC entity or a receiving UM RLC entity. If the UM RLC entity is a bidirectional entity, the UM RRC entity may be configured as a UM RLC entity consisting of a transmitting side and a receiving side. In AM, the UM RLC entity may perform functions such as segmenting and / or concatenating data received from a higher layer, adding an RLC header, and controlling data retransmission. The AM RLC entity is a bidirectional entity and may be configured as an AM RLC consisting of a transmitting side and a receiving side. Note that data provided to a lower layer in TM and / or data provided from a lower layer may be referred to as a TMD PDU. Data provided to a lower layer in UM and / or data provided from a lower layer may be referred to as a UMD PDU. Furthermore, data provided to or provided from a lower layer in AM may be called an AMD PDU. The RLC PDU format used in E-UTRA RLC may differ from the RLC PDU format used in NR RLC. RLC PDUs may include data RLC PDUs and control RLC PDUs. Data RLC PDUs may be called RLC DATA PDUs (RLC Data PDUs). Control RLC PDUs may be called RLC CONTROL PDUs (RLC Control PDUs). Control RLC PDUs used to send status reports may be called STATUS PDUs.

[0053] In the sidelink, TM may be used for SBCCH, only UM is used for groupcast and broadcast transmission, and UM and AM are available for unicast transmission. In the sidelink, UM for groupcast and broadcast transmission supports only unidirectional transmission.

[0054] An example of PDCP functionality will be described. PDCP may be called a PDCP sublayer. PDCP may have a function for maintaining sequence numbers. PDCP may also have a header compression / decompression function for efficiently transmitting user data such as IP packets and Ethernet frames over wireless interfaces. The protocol used for IP packet header compression / decompression may be called the ROHC (Robust Header Compression) protocol. The protocol used for Ethernet frame header compression / decompression may be called the EHC (Ethernet (registered trademark) Header Compression) protocol. PDCP may also have a data encryption / decryption function. PDCP may also have a data integrity protection / verification function. PDCP may also have a re-ordering function. PDCP may also have a PDCP SDU retransmission function. PDCP may also have a data discard function using a discard timer. PDCP may also have a duplication function. PDCP may also have a function for discarding duplicately received data. The PDCP entity is a bidirectional entity and may consist of a transmitting PDCP entity and a receiving PDCP entity. The PDCP PDU format used in E-UTRA PDCP may differ from that used in NR PDCP. PDCP PDUs may include data PDCP PDUs and control PDCP PDUs. The data PDCP PDU may be called a PDCP DATA PDU (PDCP Data PDU). The control PDCP PDU may be called a PDCP CONTROL PDU (PDCP Control PDU).

[0055] In addition, the following restrictions apply to PDCP functions and services on the sidelink: (1) Out-of-order delivery may be supported only with unicast transmission, and (2) Duplication on the PC5 interface is not supported.

[0056] An example of the SDAP function is described below. The SDAP is a service data adaptation protocol layer. In the sidelink, the SDAP may perform mapping between a sidelink QoS flow (PC5 QoS flow) sent from a terminal device to another terminal device and a sidelink data radio bearer (DRB). The SDAP may also store mapping rule information. The SDAP may also perform marking with a QoS flow identifier (QoSFlow ID: QFI) and a PC5 QoS flow identifier (PC5 QoS Flow ID: PQFI or PFI). SDAP PDUs may be classified as data SDAP PDUs and control SDAP PDUs. The data SDAP PDU may be called an SDAP DATA PDU (SDAP Data PDU). The control SDAP PDU may be called an SDAP CONTROL PDU (SDAP Control PDU). In the sidelink, there may be one SDAP entity in the terminal device for each destination associated with a unicast, groupcast, or broadcast transmission. Reflective QoS is not supported on the PC5 interface.

[0057] An example of RRC functionality will be described. RRC may support services and functions such as the transfer of PC5-RRC messages between peer UEs over the PC5 interface, the maintenance and release of PC5-RRC connections between two UEs, and the detection of sidelink radio link failures for PC5-RRC connections. A PC5-RRC connection is a logical connection between two UEs corresponding to a pair of source L2ID and destination L2ID, and is considered established after the corresponding PC5 unicast link is established. A PC5-RRC connection and a PC5 unicast link have a one-to-one correspondence. A UE may have multiple PC5-RRC connections with one or more UEs for different pairs of source L2ID and destination L2ID. Separate PC5-RRC procedures and messages may be used by a UE to transfer UE capabilities and sidelink configurations to a peer UE. Both peer UEs may exchange their UE capabilities and sidelink configurations with each other using separate bidirectional procedures. The UE releases the PC5-RRC connection if it is not interested in sidelink transmission, if a sidelink radio link failure is detected for the PC5-RRC connection, and if the Layer 2 link release procedure is completed.

[0058] A UE performing sidelink transmission may transmit a PSCCH and a PSSCH in association with each other. Note that sidelink transmission may involve transmitting a signal and / or data (message) via a sidelink physical channel (e.g., PSBCH, PSSCH, PSCCH), and sidelink reception may involve receiving a signal and / or data (message) via a sidelink physical channel. Communication using sidelink transmission and sidelink reception may also be referred to as sidelink communication. A UE may recognize the data (message) based on the signal. Each PSSCH transmission may be associated with a PSCCH (a PSCCH) transmission. A PSCCH transmission may carry a first SCI (first stage of the SCI) associated with the PSSCH transmission, and a second SCI (second stage of the SCI) may be carried within the resources of the PSSCH (the PSSCH). Note that a PSCCH transmission may include the first SCI, and a PSSCH transmission may include the second SCI. Furthermore, PSCCH transmission and PSSCH transmission may be referred to as sidelink transmission, and SCI may be sidelink control information. The first SCI may include information in a format called SCI format 1-A and may be used for scheduling the PSSCH and the second SCI on the PSSCH. SCI format 1-A may include information such as data priority, frequency and time resources on which the PSSCH is transmitted, resource reservation period, DMRS allocation pattern, second SCI format, beta offset indication value, number of DMRS ports, information indicating modulation and coding scheme, and other information. Furthermore, the SCI carried on the PSSCH may be the second SCI, and the second SCI may transport sidelink scheduling information and / or information related to inter-UE coordination. The second SCI may contain information in a format referred to as SCI Format 2-A, SCI Format 2-B, or SCI Format 2-C, etc.SCI Format 2-A, SCI Format 2-B, and SCI Format 2-C may include information such as HARQ process-related information, information indicating whether data is new, a redundancy version, a source ID identifying a source UE, a destination ID identifying a destination UE, and information indicating whether HARQ feedback is possible. SCI Format 2-A may additionally include information indicating a cast type and information indicating whether channel state information (CSI) is requested. SCI Format 2-B may additionally include a zone identifier and request information regarding communication range. SCI Format 2-C may additionally include information indicating whether channel state information is requested and information indicating whether inter-UE coordination information is provided or requested. When SCI Format 2-C includes information for providing inter-UE coordination information, SCI Format 2-C may additionally include information indicating a resource combination, information indicating the position of the first resource, position information of the reference slot, information indicating the type of resource set, a lowest subchannel index, and the like. When SCI format 2-C includes information requesting inter-UE coordination information, SCI format 2-C may additionally include information indicating priority, the number of subchannels, the resource reservation interval, the position of a resource selection window, the type of resource set, etc. Note that each SCI format may include information other than the above-mentioned information.

[0059] Next, the procedure for a UE to receive a PSSCH will be described. When a UE detects SCI format 1-A on a PSCCH, it can decode the PSSCH according to the detected SCI format 2-A or SCI format 2-B and the associated PSSCH resource configuration configured by a higher layer. Note that the UE does not need to decode more than one PSCCH for each PSCCH resource candidate. Also, if the UE does not support the modulation and coding scheme indicated in SCI format 1-A, it does not need to decode the corresponding SCI format 2-A or SCI format 2-B, or the PSSCH associated with SCI format 1-A.

[0060] Furthermore, if PSSCH is set in a parameter indicating whether the DMRS used for L1 RSRP measurement during a sensing operation is the DMRS of the PSCCH or the DMRS of the PSSCH in the higher (RRC) layer, the UE may measure the PSSCH RSRP from the DMRS resource elements for the PSSCH associated with the received SCI format 1-A, and if PSCCH is set, the UE may measure the PSCCH RSRP from the DMRS resource elements for the PSCCH associated with the received SCI format 1-A.

[0061] A terminal device capable of sidelink communication may perform discovery. Discovery may be performed in Model A or Model B. Figure 4 shows the protocol stack for the discovery procedure. Mode A uses a single discovery protocol message, while Model B uses two discovery protocol messages. The single discovery protocol message in Model A may be an Announcement message, and the discovery protocol messages in Model B may be a Solicitation message and a Response message. Note that the Announcement message, Solicitation message, and Response message may be collectively referred to as a Discovery message, and messages with other names used in the discovery procedure may also be referred to as Discovery messages. An overview of the procedures for Model A and Model B in ProSe Direct Discovery is provided below.

[0062] In Model A, a UE that transmits an announce message may be referred to as an announcing UE, and a UE that monitors the announce message may be referred to as a monitoring UE. The announce message may include information such as the discovery message type, ProSe Application Code or ProSe Restricted Code, and security protection element, and may also include metadata information. The announce message is transmitted using a destination layer-2 ID (L2ID) and a source layer-2 ID (L2ID), and the monitoring UE determines the destination layer-2 ID to receive the announce message. Note that the destination layer-2 ID may be the Layer-2 identifier of the destination UE, and the source layer-2 ID may be the Layer-2 identifier of the source UE. The destination UE may simply be referred to as the destination.

[0063] In Model B, a UE that sends an INVITE message may be referred to as a discoverer UE, and a UE that receives the INVITE message and / or sends a response message to the discoverer UE may be referred to as a discoveree UE. The INVITE message may include information such as a discovery message type, a ProSe Query Code, and a security protection element. The INVITE message is sent using a destination L2 ID and a source L2 ID, and the discoveree UE determines the destination L2 ID to receive the INVITE message. The discoveree UE responding to the INVITE message sends a response message. The response message may include information such as a discovery message type, a ProSe Response Code, and a security protection element, and may also include metadata information. The response message is sent using a source L2 ID, and the destination L2 ID is set to the source L2 ID of the received INVITE message.

[0064] Discovery may include types other than ProSe Direct Discovery, which discovers other UEs for direct communication with them, such as Group Member Discovery, which discovers one or more UEs for intragroup communication using a sidelink, and 5G ProSe UE-to-Network Relay Discovery, which discovers candidate relay UEs for connecting to a network via a relay UE. Note that the above-described discovery is an example of discovery provided by an application called ProSe, but other than the above-described types, different types of discovery may exist depending on the application or service performing sidelink communication. Furthermore, the information included in the discovery protocol message may differ depending on the type of discovery, and additional messages may be sent to transmit additional information.

[0065] 4 is a diagram showing an example of a protocol configuration including a discovery protocol according to this embodiment. As shown in FIG. 4, a discovery plane protocol stack including the discovery protocol may be composed of a PHY (Physical layer) 200, which is a wireless physical layer, a MAC (Medium Access Control) 202, which is a medium access control layer, a Radio Link Control (RLC) 204, which is a radio link control layer, a PDCP (Packet Data Convergence Protocol) 206, which is a packet data convergence protocol layer, and a Discovery 400, which is a discovery protocol layer. Discovery 400 may be a protocol used to process discovery-related procedures. The interface between UEs performing discovery may be referred to as PC5-D.

[0066] Multiple resource pools may be configured for transmitting messages (discovery messages) used in discovery procedures, or one or more resource pools may be configured exclusively for discovery. If a resource pool dedicated to discovery is configured, the UE may use the resource pool dedicated to discovery as the resource pool for transmitting discovery messages. If a resource pool dedicated to discovery is not configured, the UE may use the resource pool for sidelink communication as the resource pool for transmitting discovery messages. Note that multiple resource pools for sidelink communication and multiple resource pools dedicated to discovery may be configured simultaneously. Each resource pool may be configured by UE-dedicated signaling or may be configured in advance.

[0067] A Direct Communication Request (DCR) message will also be described. The Direct Communication Request message may be a message used to establish a unicast link. The DCR message may include at least a source UE identifier, and if the target UE identifier is provided by the application layer, may also include a target UE identifier. It may also include other information, such as security information and application information. The DCR message may be transmitted unicast or broadcast using a source L2 ID and a destination L2 ID. The discovery message and the DCR message may be transmitted via sidelink. The discovery message may be integrated into the DCR message. When the discovery message integrated into the DCR message is used for U2N relay or U2U relay, the DCR message may additionally include information indicating that the message is for relay (relay_indication), for example.

[0068] A sidelink signaling radio bearer (SRB) may be configured for each unicast PC5-RRC connection. A sidelink SRB used to transmit PC5-S messages before PC5-S security is established may be referred to as SL-SRB0. A sidelink SRB used to transmit PC5-S messages for establishing PC5-S security may be referred to as SL-SRB1. A sidelink SRB used to transmit protected PC5-S messages after PC5-S security is established may be referred to as SL-SRB2. A sidelink SRB used to transmit protected PC5-RRC signaling after PC5-S security is established may be referred to as SL-SRB3. A sidelink SRB used to transmit and / or receive discovery messages in NR may be referred to as SL-SRB4. Note that PC5-RRC signaling may be RRC signaling between UEs transmitted over PC5. Note that PC5-RRC signaling may be referred to as a PC5-RRC message, etc.

[0069] Here, a UE-to-Network (U2N) relay will be described. A U2N relay may be a function that provides network connectivity to a remote terminal device (Remote UE). A remote terminal device that connects to a network using a U2N relay may be referred to as a U2N Remote UE. A terminal device that provides network connectivity to a U2N Remote UE may be referred to as a U2N relay terminal device (Relay UE) or simply as a relay terminal device (Relay UE). A U2N Relay UE may use a Uu interface for communication with a base station device, or a PC5 interface for communication with a U2N Remote UE. A U2N relay may be classified into types such as a Layer 2 (L2) U2N relay and a Layer 3 (L3) U2N relay. A remote terminal device in an L2 U2N relay may be particularly referred to as an L2 U2N Remote UE, and a relay terminal device in an L2 U2N relay may be particularly referred to as an L2 U2N Relay UE. Furthermore, the L2 U2N relay may include a Sidelink Relay Adaptation Protocol (SRAP) layer (SRAP layer) 800. Note that the SRAP 800 may be simply referred to as an SRAP.

[0070] FIG. 8 is a diagram showing an example of a protocol configuration of a control plane (C-plane) of an L2 U2N relay, including an SRAP layer (SRAP 800) according to this embodiment. FIG. 9 is a diagram showing an example of a protocol configuration of a user plane (U-plane) of an L2 U2N relay, including an SRAP layer according to this embodiment. As shown in FIGS. 8 and 9, the SRAP layer may be associated between a Remote UE and a Relay UE, or may be associated between a Relay UE and a gNB 102. The gNB 102 shown in FIGS. 8 and 9 may be an ng-eNB 100. The Remote UE or the Relay UE may be a UE 122. The Relay UE may have the same configuration as the UE 122.

[0071] The SRAP layer will now be described. The SRAP layer may be referred to as the SRAP sublayer, or simply as SRAP. The SRAP sublayer may reside above the RLC sublayer for the control plane and user plane of both the PC5 interface and the Uu interface. The SRAP sublayer on the PC5 interface may be used for bearer mapping. In an L2 U2N Relay UE, the SRAP sublayer may include one SRAP entity on the Uu interface and a separate collocated SRAP entity on the PC5 interface. In an L2 U2N Remote UE, the SRAP sublayer may include only one SRAP entity on the PC5 interface. The SRAP entity associated between the Remote UE and Relay UE via the PC5 interface may be specifically referred to as PC5-SRAP, and the SRAP entity associated between the Relay UE and gNB via the Uu may be specifically referred to as Uu-SRAP. To clarify the interface names, other entities may also be expressed in the format (interface name)-(entity name), similar to the SRAP. Each SRAP entity may have a transmitter and a receiver. On the PC5 interface, the transmitter of the SRAP entity of the L2 U2N Remote UE may be associated with the receiver of the SRAP entity of the L2 U2N Relay UE, and the receiver of the SRAP entity of the L2 U2N Remote UE may be associated with the transmitter of the SRAP entity of the L2 U2N Relay UE. Also, on the Uu interface, the transmitter of the SRAP entity of the L2 U2N Relay UE may be associated with the receiver of the SRAP entity of the gNB102, and the receiver of the SRAP entity of the L2 U2N Relay UE may be associated with the transmitter of the SRAP entity of the gNB102.

[0072] The SRAP entity may also have the functions of forwarding data, determining the UE ID field and bearer ID field of the SRAP header to be added to the data packet, determining the egress link, and determining the egress RLC channel.

[0073] Also, in Figures 8 and 9, a PC5 Relay RLC channel may be established between the Remote UE and the Relay UE, and a Uu Relay RLC channel may be established between the Relay UE and the gNB102.

[0074] Multi-hop relay will now be described. A multi-hop relay may be a U2N relay in which multiple relay terminal devices are involved in a single path from a remote terminal device to a gNB 102. FIG. 11 shows an example of a C-plane protocol stack in a multi-hop relay. For example, among the multiple relay terminal devices, a relay terminal device directly connected to the gNB 102 via the Uu interface may be referred to as a last relay terminal device (MH U2N Last Relay UE in FIG. 11). Among the multiple relay terminal devices, relay terminal devices other than the last relay terminal device (UEs belonging to the dotted line including the MH U2N First Relay UE in FIG. 11) may be referred to as intermediate relay terminal devices. The intermediate relay terminal devices may be referred to as a first relay terminal device, a second relay terminal device, a third relay terminal device, etc. in order of hop proximity to the remote terminal device. The multiple relay terminal devices may be terminal devices that provide connectivity to the gNB to the remote terminal device. The names of the terminal devices described above are merely examples and are not limiting. Note that FIG. 11 shows an example of a C-plane protocol stack, and the implementation method is not limited thereto. A similar structure may also be used for the U-plane protocol stack. For example, an SDAP layer may be used instead of the RRC layer in the figure. In addition, in a multi-hop relay, when the node at which the link with the remote UE terminates is a base station device as shown in Figure 11, it may be called a multi-hop U2N relay, and when the node at which the link with the remote UE terminates is a UE, it may be called a multi-hop U2U relay.

[0075] Next, the protocol configuration used between the base station device and the terminal device will be described. In the communication performed over the Uu interface between the relay terminal device and the base station device, and in the communication performed between the remote terminal device and the base station device via the relay terminal device, the protocol used between the base station device and the terminal device may be used. Note that in the communication performed between the remote terminal device and the base station device via the relay terminal device, some protocols may not be associated between the remote terminal device and the base station device.

[0076] FIG. 7 is a diagram showing an example of an NR protocol configuration according to this embodiment. The functions of each protocol described using FIG. 7 are some of the functions closely related to this embodiment, and other functions may also be included. In this embodiment, an uplink (UL) may be a link from a terminal device to a base station device. Also, in this embodiment, a downlink (DL) may be a link from a base station device to a terminal device.

[0077] FIG. 7A is a diagram of the NR control plane (CP) protocol stack. As shown in FIG. 7A, the NR CP protocol may be a protocol between the UE 122 and the gNB 102. That is, the NR CP protocol may be a protocol terminated at the gNB 102 on the network side. As shown in FIG. 7A, the NR control plane protocol stack may be composed of a PHY (Physical layer) 700, a MAC (Medium Access Control) 702, a RLC (Radio Link Control) 704, a PDCP (Packet Data Convergence Protocol) 706, and a RRC (Radio Resource Control) 708. FIG. 7B is a diagram of the NR user plane (UP) protocol stack. As shown in Figure 7(B), the NR UP protocol may be a protocol between the UE 122 and the gNB 102. That is, the NR UP protocol may be a protocol that terminates at the gNB 102 on the network side. As shown in Figure 7(B), the NR user plane protocol stack may be composed of a radio physical layer PHY 700, a medium access control layer MAC 702, a radio link control layer RLC 704, a packet data convergence protocol layer PDCP 706, and a service data adaptation protocol layer SDAP (Service Data Adaptation Protocol) 710.

[0078] The AS (Access Stratum) layer may be a layer that terminates between the UE 122 and the gNB 102. In other words, the AS layer may be a layer that includes some or all of the PHY 700, MAC 702, RLC 704, PDCP 706, and RRC 708. The gNB 102 may also be an ng-eNB 100. Although only the NR protocol is shown, the E-UTRA protocol may also be used. In the E-UTRA protocol, the SDAP 710 may not exist, and the E-UTRA protocol may have some functions that differ from those of the NR protocol.

[0079] In the present embodiment, the terms PHY (PHY layer), MAC (MAC layer), RLC (RLC layer), PDCP (PDCP layer), and RRC (RRC layer) may be used without distinguishing between the E-UTRA protocol and the NR protocol. In this case, PHY (PHY layer), MAC (MAC layer), RLC (RLC layer), PDCP (PDCP layer), and RRC (RRC layer) may respectively refer to the PHY (PHY layer), MAC (MAC layer), RLC (RLC layer), PDCP (PDCP layer), and RRC (RRC layer) of the E-UTRA protocol, or the PHY (PHY layer), MAC (MAC layer), RLC (RLC layer), PDCP (PDCP layer), and RRC (RRC layer) of the NR protocol. Furthermore, SDAP (SDAP layer) may refer to the SDAP (SDAP layer) of the NR protocol.

[0080] In this embodiment, when distinguishing between E-UTRA protocols and NR protocols, the PHY 500, MAC 502, RLC 504, PDCP 506, and RRC 508 may be referred to as E-UTRA PHY or LTE PHY, E-UTRA MAC or LTE MAC, E-UTRA RLC or LTE RLC, E-UTRA PDCP or LTE PDCP, and E-UTRA RRC or LTE RRC, respectively. The PHY 500, MAC 502, RLC 504, PDCP 506, and RRC 508 may also be referred to as E-UTRA PHY or LTE PHY, E-UTRA MAC or LTE MAC, E-UTRA RLC or LTE RLC, E-UTRA PDCP or LTE PDCP, and E-UTRA RRC or LTE RRC, respectively. Furthermore, when distinguishing between E-UTRA protocols and NR protocols, PHY 500, MAC 502, RLC 504, PDCP 506, and RRC 508 may be referred to as NR PHY, NR MAC, NR RLC, NR RLC, and NR RRC, respectively. PHY 500, MAC 502, RLC 504, PDCP 506, and RRC 508 may also be referred to as NR PHY, NR MAC, NR RLC, NR PDCP, and NR RRC, respectively.

[0081] This section describes entities in the AS layer of E-UTRA and / or NR. An entity having some or all of the physical layer functions may be referred to as a PHY entity. An entity having some or all of the MAC layer functions may be referred to as a MAC entity. An entity having some or all of the RLC layer functions may be referred to as an RLC entity. An entity having some or all of the PDCP layer functions may be referred to as a PDCP entity. An entity having some or all of the SDAP layer functions may be referred to as an SDAP entity. An entity having some or all of the RRC layer functions may be referred to as an RRC entity. The PHY entity, MAC entity, RLC entity, PDCP entity, SDAP entity, and RRC entity may be referred to as PHY, MAC, RLC, PDCP, SDAP, and RRC, respectively.

[0082] Note that data provided from MAC, RLC, PDCP, and SDAP to lower layers, and / or data provided from lower layers to MAC, RLC, PDCP, and SDAP, may be referred to as MAC PDU (Protocol Data Unit), RLC PDU, PDCP PDU, and SDAP PDU, respectively. Data provided from higher layers to MAC, RLC, PDCP, and SDAP, and / or data provided from MAC, RLC, PDCP, and SDAP to higher layers, may be referred to as MAC SDU (Service Data Unit), RLC SDU, PDCP SDU, and SDAP SDU, respectively. A segmented RLC SDU may be referred to as an RLC SDU segment.

[0083] Here, the base station apparatus and the terminal apparatus exchange (transmit and receive) signals in a higher layer. The higher layer may be referred to as an upper layer, and the terms may be interchangeable. For example, the base station apparatus and the terminal apparatus may transmit and receive RRC messages (also referred to as RRC signaling) in a Radio Resource Control (RRC) layer. The base station apparatus and the terminal apparatus may also transmit and receive MAC control elements in a Medium Access Control (MAC) layer. The RRC layer of the terminal apparatus acquires system information broadcast from the base station apparatus. Here, the RRC messages, system information, and / or MAC control elements are also referred to as higher layer signals (higher layer signaling) or higher layer parameters (higher layer parameters). Each of the parameters included in the higher layer signals received by the terminal apparatus may be referred to as a higher layer parameter. For example, in PHY layer processing, an upper layer means a layer higher than the PHY layer, and therefore may mean one or more of a MAC layer, an RRC layer, an RLC layer, a PDCP layer, an NAS (Non Access Stratum) layer, etc. For example, in MAC layer processing, an upper layer may mean one or more of an RRC layer, an RLC layer, a PDCP layer, an NAS layer, etc.

[0084] Hereinafter, the meaning of "A is given (provided) by an upper layer" or "A is given (provided) by an upper layer" may mean that an upper layer (mainly an RRC layer, a MAC layer, etc.) of a terminal device receives A from a base station device, and the received A is given (provided) to a physical layer of the terminal device from the upper layer of the terminal device. For example, in a terminal device, "being provided with upper layer parameters" may mean receiving an upper layer signal from a base station device, and providing upper layer parameters included in the received upper layer signal from the upper layer of the terminal device to the physical layer of the terminal device. Setting upper layer parameters in a terminal device may mean that the upper layer parameters are given (provided) to the terminal device. For example, setting upper layer parameters in a terminal device may mean that the terminal device receives an upper layer signal from a base station device and sets the received upper layer parameters in the upper layer. However, setting upper layer parameters in a terminal device may also include setting default parameters that are given in advance to the upper layer of the terminal device. When describing transmission of an RRC message from a terminal device to a base station device, the expression "submitting a message from the RRC entity of the terminal device to a lower layer" may be used. In a terminal device, "submitting a message to a lower layer" from an RRC entity may mean submitting a message to a PDCP layer. In a terminal device, "submitting a message to a lower layer" from an RRC layer may mean submitting to a PDCP entity corresponding to each SRB, since RRC messages are transmitted using SRBs (SRB0, SRB1, SRB2, SRB3, etc.). When the RRC entity of the terminal device receives an indication from a lower layer, the lower layer may mean one or more of a PHY layer, a MAC layer, an RLC layer, a PDCP layer, etc.

[0085] An example of the functions of the PHY will be described. The PHY of the terminal device may have a function to receive data transmitted from the PHY of the base station device via a downlink (DL) physical channel. The PHY of the terminal device may have a function to transmit data to the PHY of the base station device via an uplink (UL) physical channel. The PHY may be connected to a higher MAC via a transport channel. The PHY may pass data to the MAC via the transport channel. The PHY may also be provided with data from the MAC via the transport channel. In the PHY, an RNTI (Radio Network Temporary Identifier) ​​may be used to identify various control information.

[0086] Here, the physical channels will be described. The physical channels used for wireless communication between a terminal device and a base station device may include the following physical channels.

[0087] PBCH (Physical Broadcast CHannel) PDCCH (Physical Downlink Control CHannel) PDSCH (Physical Downlink Shared CHannel) PUCCH (Physical Uplink Control CHannel) PUSCH (Physical Uplink Shared CHannel) PRACH (Physical Random Access CHannel)

[0088] The PBCH may be used to broadcast system information required by a terminal device.

[0089] In addition, in NR, the PBCH may be used to broadcast a time index (SSB-Index) within a synchronization signal block (SSB) period.

[0090] The PDCCH may be used to transmit (or carry) downlink control information (DCI) in downlink wireless communication (wireless communication from a base station device to a terminal device). Here, one or more DCIs (which may also be referred to as DCI formats) may be defined for transmitting the downlink control information. That is, a field for the downlink control information may be defined as DCI and mapped to information bits. The PDCCH may be transmitted in PDCCH candidates. The terminal device may monitor a set of PDCCH candidates in a serving cell. Monitoring the set of PDCCH candidates may mean attempting to decode the PDCCH according to a certain DCI format. Furthermore, the terminal device may monitor the PDCCH candidates at configured monitoring occasions in one or more configured control resource sets (CORESETs) configured by search space configuration. The DCI format may be used for scheduling the PUSCH in the serving cell. The PUSCH may be used for transmitting user data, transmitting RRC messages (described later), and the like.

[0091] PDCCH repetition may be operated by using two search space sets that are explicitly linked by a configuration provided by a higher layer (RRC layer). The two linked search space sets may also be associated with a corresponding CORESET. For PDCCH repetition, the two linked search space sets may be configured in the terminal device with the same number of PDCCH candidates. Two PDCCH candidates in the two linked search space sets may be linked by the same candidate index. When PDCCH repetition is scheduled in the terminal device, inter-slot repetition may be allowed, and each repetition may have the same number of control channel elements (CCEs) and coded bits, and the same DCI payload.

[0092] The PUCCH may be used to transmit uplink control information (UCI) in uplink wireless communication (wireless communication from a terminal device to a base station device). Here, the uplink control information may include channel state information (CSI) used to indicate the state of a downlink channel. The uplink control information may also include a scheduling request (SR) used to request an uplink shared channel (UL-SCH) resource. The uplink control information may also include a hybrid automatic repeat reQuest ACKnowledgement (HARQ-ACK).

[0093] The PDSCH may be used to transmit downlink data (DL-SCH: Downlink Shared CHannel) from the MAC layer, and may also be used to transmit system information (SI) and random access responses (RAR) in the downlink.

[0094] The PUSCH may be used to transmit uplink data from the MAC layer (UL-SCH: Uplink Shared CHannel) or HARQ-ACK and / or CSI together with uplink data. The PUSCH may also be used to transmit only CSI, or only HARQ-ACK and CSI. That is, the PUSCH may be used to transmit only UCI. The PDSCH or PUSCH may also be used to transmit RRC messages and MAC CE (described later). Here, in the PDSCH, an RRC message transmitted from a base station apparatus may be signaling common to multiple terminal apparatuses within a cell. The RRC message transmitted from a base station apparatus may also be signaling dedicated to a certain terminal apparatus. That is, terminal apparatus-specific information may be transmitted using signaling dedicated to a certain terminal apparatus. The PUSCH may also be used to transmit UE capabilities in the uplink.

[0095] The PRACH may be used to transmit a random access preamble and may be used to indicate initial connection establishment procedures, handover procedures, connection re-establishment procedures, synchronization (timing adjustment) for uplink transmissions, and requests for UL-SCH resources.

[0096] An example of the MAC function will be described. The MAC may be referred to as a MAC sublayer. The MAC may have the function of mapping various logical channels to corresponding transport channels. The logical channels may be identified by a logical channel identity (or logical channel ID). The MAC may be connected to the higher-level RLC via logical channels. Depending on the type of information to be transmitted, the logical channels may be divided into control channels that transmit control information and traffic channels that transmit user information. The logical channels may also be divided into uplink logical channels and downlink logical channels. The MAC may have the function of multiplexing MAC SDUs belonging to one or more different logical channels and providing them to the PHY. The MAC may also have the function of demultiplexing MAC PDUs provided by the PHY and providing them to the higher layer via the logical channel to which each MAC SDU belongs. The MAC may also have the function of performing error correction through HARQ (Hybrid Automatic Repeat reQuest). The MAC may also have the function of reporting scheduling information. The MAC may also have the function of prioritizing processing between terminal devices using dynamic scheduling. The MAC may also have the function of prioritizing processing between logical channels within one terminal device. The MAC may also have the function of prioritizing processing of overlapping resources within one terminal device. The E-UTRA MAC may have the function of identifying Multimedia Broadcast Multicast Services (MBMS). The NR MAC may also have the function of identifying Multicast Broadcast Service (MBS). The MAC may have the function of selecting a transport format.The MAC may have functions such as discontinuous reception (DRX) and / or discontinuous transmission (DTX), a random access (RA) procedure, a power headroom report (PHR) function that notifies information about available transmission power, and a buffer status report (BSR) function that notifies information about the amount of data in the transmission buffer. The NR MAC may also have a bandwidth adaptation (BA) function. The MAC PDU format used in the E-UTRA MAC may differ from that used in the NR MAC. The MAC PDU may also include a MAC control element (MAC CE), which is an element for controlling the MAC.

[0097] This section describes logical channels for uplink (UL) and / or downlink (DL) used in E-UTRA and / or NR.

[0098] The BCCH (Broadcast Control Channel) may be a downlink logical channel for broadcasting control information such as system information (SI).

[0099] A PCCH (Paging Control Channel) may be a downlink logical channel for carrying paging messages.

[0100] A CCCH (Common Control Channel) may be a logical channel for transmitting control information between a terminal device and a base station device. The CCCH may be used when the terminal device does not have an RRC connection. The CCCH may also be used between a base station device and multiple terminal devices.

[0101] A DCCH (Dedicated Control Channel) may be a logical channel for transmitting dedicated control information bidirectionally, point-to-point, between a terminal device and a base station device. The dedicated control information may be control information dedicated to each terminal device. The DCCH may be used when the terminal device has an RRC connection.

[0102] A DTCH (Dedicated Traffic Channel) may be a logical channel for transmitting user data point-to-point between a terminal device and a base station device. A DTCH may be a logical channel for transmitting dedicated user data. Dedicated user data may be user data dedicated to each terminal device. A DTCH may exist in both uplink and downlink.

[0103] This section describes the mapping of logical channels and transport channels for the uplink in E-UTRA and / or NR.

[0104] The CCCH may be mapped to an uplink shared channel (UL-SCH), which is an uplink transport channel.

[0105] The DCCH may be mapped to an uplink shared channel (UL-SCH), which is an uplink transport channel.

[0106] The DTCH may be mapped to an uplink shared channel (UL-SCH), which is an uplink transport channel.

[0107] This section describes the mapping of logical channels and transport channels for the downlink in E-UTRA and / or NR.

[0108] The BCCH may be mapped to a downlink transport channel, a Broadcast Channel (BCH) and / or a Downlink Shared Channel (DL-SCH).

[0109] The PCCH may be mapped to a PCH (Paging Channel), which is a downlink transport channel.

[0110] The CCCH may be mapped to a DL-SCH (Downlink Shared Channel), which is a downlink transport channel.

[0111] The DCCH may be mapped to a DL-SCH (Downlink Shared Channel), which is a downlink transport channel.

[0112] The DTCH may be mapped to a DL-SCH (Downlink Shared Channel), which is a downlink transport channel.

[0113] An example of the RLC function will be described. The RLC may also be called an RLC sublayer. The E-UTRA RLC may have the function of segmenting and / or concatenating data provided by the PDCP in the upper layer and providing it to the lower layer. The E-UTRA RLC may have the function of reassembling and reordering data provided by the lower layer and providing it to the upper layer. The NR RLC may have the function of adding a sequence number independent of the sequence number added by PDCP to data provided by the PDCP in the upper layer. The NR RLC may also have the function of segmenting data provided by PDCP and providing it to the lower layer. The NR RLC may also have the function of reassembling data provided by the lower layer and providing it to the upper layer. The RLC may also have the function of data retransmission and / or retransmission request (Automatic Repeat reQuest: ARQ). RLC may also have a function for performing error correction using ARQ. The control information sent from the receiving side of RLC to the transmitting side to indicate data that needs to be retransmitted for ARQ may be called a status report. The instruction to send a status report sent from the transmitting side of RLC to the receiving side may be called a poll. RLC may also have a function for detecting data duplication. RLC may also have a function for discarding data. RLC may have three modes: transparent mode (TM), unacknowledged mode (UM), and acknowledged mode (AM). In TM, data received from the upper layer is not segmented, and no RLC header needs to be added. The TM RLC entity is a unidirectional entity and may be configured as a transmitting TM RLC entity or a receiving TM RLC entity.In UM, the UM RLC entity performs functions such as segmenting and / or concatenating data received from a higher layer and adding an RLC header, but does not require data retransmission control. The UM RLC entity may be a unidirectional or bidirectional entity. If the UM RLC entity is a unidirectional entity, it may be configured as a transmitting UM RLC entity or a receiving UM RLC entity. If the UM RLC entity is a bidirectional entity, the UM RRC entity may be configured as a UM RLC entity consisting of a transmitting side and a receiving side. In AM, the UM RLC entity may perform functions such as segmenting and / or concatenating data received from a higher layer, adding an RLC header, and controlling data retransmission. The AM RLC entity is a bidirectional entity and may be configured as an AM RLC consisting of a transmitting side and a receiving side. Note that data provided to a lower layer in TM and / or data provided from a lower layer may be referred to as a TMD PDU. Data provided to a lower layer in UM and / or data provided from a lower layer may be referred to as a UMD PDU. Furthermore, data provided to or from a lower layer in AM may be referred to as an AMD PDU. The RLC PDU format used in E-UTRA RLC may differ from the RLC PDU format used in NR RLC. RLC PDUs may include data RLC PDUs and control RLC PDUs. Data RLC PDUs may be referred to as RLC DATA PDUs (RLC Data PDUs). Control RLC PDUs may be referred to as RLC CONTROL PDUs (RLC Control PDUs).

[0114] An example of PDCP functions will be described. PDCP may be called a PDCP sublayer. PDCP may have a function for maintaining sequence numbers. PDCP may also have a header compression / decompression function for efficiently transmitting user data such as IP packets and Ethernet frames over wireless interfaces. The protocol used for IP packet header compression / decompression may be called the ROHC (Robust Header Compression) protocol. The protocol used for Ethernet frame header compression / decompression may be called the EHC (Ethernet (registered trademark) Header Compression) protocol. PDCP may also have a data encryption / decryption function. PDCP may also have a data integrity protection / verification function. PDCP may also have a reordering function. PDCP may also have a PDCP SDU retransmission function. PDCP may also have a data discard function using a discard timer. PDCP may also have a duplication function. PDCP may also have a function for discarding duplicately received data. The PDCP entity is a bidirectional entity and may consist of a transmitting PDCP entity and a receiving PDCP entity. The PDCP PDU format used in E-UTRA PDCP may differ from that used in NR PDCP. PDCP PDUs may include data PDCP PDUs and control PDCP PDUs. The data PDCP PDU may be called a PDCP DATA PDU (PDCP Data PDU). The control PDCP PDU may be called a PDCP CONTROL PDU (PDCP Control PDU).

[0115] An example of SDAP functionality will be described. SDAP is a service data adaptation protocol layer. SDAP may have the function of mapping a downlink QoS flow sent from 5GC to a terminal device via a base station device to a data radio bearer (DRB), and / or mapping an uplink QoS flow sent from the terminal device via a base station device to a DRB. SDAP may also have the function of storing mapping rule information. SDAP may also have the function of marking a QoS flow identifier (QoS Flow ID: QFI). SDAP PDUs may include data SDAP PDUs and control SDAP PDUs. Data SDAP PDUs may be called SDAP DATA PDUs (SDAP Data PDUs). Control SDAP PDUs may be called SDAP CONTROL PDUs (SDAP Control PDUs). There may be one SDAP entity in a terminal device for each PDU session.

[0116] An example of the functions of the RRC will be described. The RRC may have a broadcast function. The RRC may have a paging function from the 5GC. The RRC may have a paging function from the gNB 102 or the ng-eNB 100. The RRC may also have an RRC connection management function. The RRC may also have a radio bearer control function. The RRC may also have a cell group control function. The RRC may also have a mobility control function. The RRC may also have terminal device measurement reporting and terminal device measurement reporting control functions. The RRC may also have a QoS management function. The RRC may also have a radio link failure detection and recovery function. The RRC may use RRC messages to perform broadcasting, paging, RRC connection management, radio bearer control, cell group control, mobility control, terminal device measurement reporting and terminal device measurement reporting control, QoS management, radio link failure detection and recovery, etc. Note that the RRC messages and parameters used in E-UTRA RRC may be different from those used in NR RRC. Note that the RRC message may include multiple information elements (IEs) for performing the above-mentioned control.

[0117] RRC messages may be sent using the logical channel BCCH, the logical channel PCCH, the logical channel CCCH, or the logical channel DCCH, and RRC messages sent using the DCCH are referred to as dedicated RRC signaling, or RRC signaling.

[0118] The RRC messages sent using the BCCH may include, for example, a Master Information Block (MIB), various types of System Information Blocks (SIBs), or other RRC messages.The RRC messages sent using the PCCH may include, for example, paging messages or other RRC messages.

[0119] RRC messages transmitted in the uplink (UL) direction using the CCCH may include, for example, an RRC setup request message (RRC Setup Request), an RRC resume request message (RRC Resume Request), an RRC reestablishment request message (RRC Reestablishment Request), an RRC system information request message (RRC System Info Request), etc. Also, for example, an RRC connection request message (RRC Connection Request), an RRC connection resume request message (RRC Connection Resume Request), an RRC connection reestablishment request message (RRC Connection Reestablishment Request), etc. Other RRC messages may also be included.

[0120] The RRC message transmitted in the downlink (DL) direction using the CCCH may include, for example, an RRC connection reject message (RRC Connection Reject), an RRC connection setup message (RRC Connection Setup), an RRC connection reestablishment message (RRC Connection Reestablishment Reject), an RRC connection reestablishment reject message (RRC Connection Reestablishment Reject), etc. Also, for example, an RRC reject message (RRC Reject), an RRC setup message (RRC Setup), etc. Also, other RRC messages may be included.

[0121] The RRC signaling sent in the uplink (UL) direction using the DCCH may include, for example, a Measurement Report message, an RRC Connection Reconfiguration Complete message, an RRC Connection Setup Complete message, an RRC Connection Reestablishment Complete message, a Security Mode Complete message, a UE Capability Information message, etc. Also, for example, a Measurement Report message, an RRC Reconfiguration Complete message, an RRC Setup Complete message, an RRC Reestablishment Complete message, an RRC Resume Complete message, a Security Mode Complete message, a UE Capability Information message, etc. Also, other RRC signaling may be included.

[0122] The RRC signaling sent in the downlink (DL) direction using the DCCH may include, for example, an RRC connection reconfiguration message, an RRC connection release message, a security mode command message, a UE capability inquiry message, etc. Also, for example, an RRC reconfiguration message, an RRC resume message, an RRC release message, an RRC reestablishment message, a security mode command message, a UE capability inquiry message, etc. Also, other RRC signaling may be included.

[0123] The above-mentioned functions of PHY, MAC, RLC, PDCP, SDAP, and RRC are merely examples, and some or all of the functions may not be implemented. Also, some or all of the functions of each layer may be included in other layers.

[0124] Radio bearers will now be described. When a terminal device communicates with a base station device, a radio connection may be established by establishing a radio bearer (RB) between the terminal device and the base station device. A radio bearer used for CP may be called a signaling radio bearer (SRB). A radio bearer used for UP may be called a data radio bearer (DRB). Each radio bearer may be assigned a radio bearer identity (ID). A radio bearer identifier for an SRB may be called an SRB identity (SRB ID). A radio bearer identifier for a DRB may be called a DRB identity (DRB ID). SRB0 to SRB2 may be defined for the SRB of E-UTRA, or other SRBs may be defined. SRB0 to SRB3 may be defined for the SRB of NR, or other SRBs may be defined. SRB0 may be an SRB for RRC messages transmitted and / or received using the logical channel CCCH. SRB1 may be an SRB for RRC signaling and for NAS signaling before the establishment of SRB2. The RRC signaling transmitted and / or received using SRB1 may include piggybacked NAS signaling. The logical channel DCCH may be used for all RRC and NAS signaling transmitted and / or received using SRB1. SRB2 may be an SRB for NAS signaling and RRC signaling including logged measurement information. The logical channel DCCH may be used for all RRC and NAS signaling transmitted and / or received using SRB2. SRB2 may also have a lower priority than SRB1. SRB3 may be an SRB for transmitting and / or receiving specific RRC signaling when EN-DC, NGEN-DC, NR-DC, etc. are configured in the terminal device.All RRC and NAS signaling transmitted and / or received using SRB3 may use the logical channel DCCH. Other SRBs may also be provided for other uses. DRBs may be radio bearers for user data. RRC signaling transmitted and / or received using DRBs may use the logical channel DTCH.

[0125] The following describes radio bearers in a terminal device. A radio bearer may include an RLC bearer. An RLC bearer may consist of one or two RLC entities and logical channels. When an RLC bearer has two RLC entities, the RLC entities may be a TM RLC entity and / or a transmitting RLC entity and a receiving RLC entity in a unidirectional UM mode RLC entity. SRB0 may consist of one RLC bearer. The RLC bearer of SRB0 may consist of a TM RLC entity and a logical channel. SRB0 may always be established in a terminal device in all RRC states (such as RRC idle state, RRC connected state, and RRC inactive state). SRB1 may be established and / or configured in the terminal device by RRC signaling received from the base station device when the terminal device transitions from the RRC idle state to the RRC connected state. SRB1 may consist of one PDCP entity and one or more RLC bearers. The RLC bearer of SRB1 may consist of an AM RLC entity and a logical channel. SRB2 may be established and / or configured in a terminal device in an RRC connected state with AS security activated by RRC signaling received from a base station device. SRB2 may consist of one PDCP entity and one or more RLC bearers. The RLC bearer of SRB2 may consist of an AM RLC entity and a logical channel. Note that the PDCP on the base station device side of SRB1 and SRB2 may be placed in the master node. SRB3 may be established and / or configured in a terminal device in an RRC connected state with AS security activated by RRC signaling received from a base station device when a secondary node in EN-DC, NGEN-DC, or NR-DC is added or when the secondary node is changed. SRB3 may be a direct SRB between the terminal device and the secondary node. SRB3 may consist of one PDCP entity and one or more RLC bearers. The RLC bearer of SRB3 may consist of an AM RLC entity and a logical channel.The PDCP on the base station side of the SRB3 may be placed in a secondary node. One or more DRBs may be established and / or configured in a terminal device by RRC signaling received from the base station when the terminal device is in an RRC connected state with AS security activated. A DRB may consist of one PDCP entity and one or more RLC bearers. An RLC bearer of a DRB may consist of an AM or UM RLC entity and a logical channel.

[0126] For an RLC bearer established and / or configured in a cell group configured with E-UTRA, the RLC entity established and / or configured may be an E-UTRA RLC. For an RLC bearer established and / or configured in a cell group configured with NR, the RLC entity established and / or configured may be an NR RLC. When an EN-DC is configured in a terminal device, a PDCP entity established and / or configured for a master node (MN)-terminated MCG bearer may be either an E-UTRA PDCP or an NR PDCP. When an EN-DC is configured in a terminal device, a PDCP entity established and / or configured for radio bearers of other bearer types, i.e., an MN-terminated split bearer, an MN-terminated SCG bearer, an SN-terminated MCG bearer, an SN-terminated split bearer, and an SN-terminated SCG bearer, may be an NR PDCP. Also, when NGEN-DC, NE-DC, or NR-DC is configured in the terminal device, the PDCP entity established and / or configured for radio bearers of all bearer types may be an NR PDCP.

[0127] In NR, a DRB established and / or configured in a terminal device may be associated with one PDU session. One SDAP entity may be established and / or configured for one PDU session in the terminal device. The SDAP entity, PDCP entity, RLC entity, and logical channels established and / or configured in the terminal device may be established and / or configured by RRC signaling received by the terminal device from the base station device.

[0128] The reference signal received power (RSRP) measured in the sidelink may be, for example, the following RSRPs. In addition, the following RSRPs may be referred to as SL-RSRPs: (a) PSBCH RSRP, (b) PSSCH RSRP, and (c) PSCCH RSRP.

[0129] The PSBCH-RSRP (PSBCH RSRP) may be defined as a linear average of power contributions of resource elements transmitting multiple Demodulation Reference Signals (DMRSs) associated with the PSBCH. Furthermore, the PSSCH-RSRP (PSSCH RSRP) may be defined as a linear average of power contributions of resource elements of antenna ports transmitting multiple DMRSs associated with the PSSCH. In the case of multiple antenna ports, the RSRP values ​​for each antenna port may be summed. The PSCCH-RSRP (PSCCH RSRP) may be defined as a linear average of power contributions of resource elements transmitting multiple DMRSs associated with the PSCCH. The DMRSs may be used to demodulate, for example, the PSBCH, PSSCH, and PSCCH signals. Furthermore, a terminal device performing sidelink communication with another terminal device may measure the RSRP (SL-RSRP) of the sidelink communication using the PSSCH or PSCCH transmitted from the other terminal device. The terminal device may also measure the RSRP (SD-RSRP) of the discovery message using, for example, the power contribution of the resource element that transmits the DMRS associated with the discovery message.

[0130] In addition to the SL-RSRP, the UE 122 may measure the following quantities in the sidelink measurements: (a) Sidelink received signal strength indicator (SL RSSI), (b) Sidelink channel occupancy ratio (SL CR), and (c) Sidelink channel busy ratio (SL CBR).

[0131] The SL RSSI may be defined as the linear average of the power ([W]) observed on the configured subchannels in the OFDM symbols of the slots configured for the PSCCH and PSSCH, starting from the second OFDM symbol. The SL CR for slot n may be defined as the sum of the number of subchannels used for sidelink transmission from slot [na] to slot [n-1] and the number of subchannels allocated from slot [n] to slot [n+b], divided by the total number of subchannels configured from slot [na] to slot [n+b]. The SL CBR for slot n may be defined as the percentage of subchannels in the resource pool whose SL RSSI exceeds a threshold during a period configured as a CBR measurement window (slot [na] to slot [n-1]).

[0132] After discovering candidate L2 U2N Relay UEs and measuring the RSRPs of the candidate L2 U2N Relay UEs, the L2 U2N Remote UE may report one or more candidate L2 U2N Relay UEs to a base station device. Before reporting one or more candidate L2 U2N Relay UEs to a base station device, the L2 U2N Remote UE may determine whether the measured RSRPs of the candidate L2 U2N Relay UEs satisfy an L2 U2N relay selection criterion. The L2 U2N Remote UE may report only candidate L2 U2N Relay UEs that satisfy the selection criterion and match upper layer criteria to a base station device. When reporting one or more candidate L2 U2N Relay UEs to a base station device, the L2 U2N Remote UE may include identification information of the candidate L2 U2N Relay UEs, identification information of the serving cells of the candidate L2 U2N Relay UEs, and the measurement results in the report to the base station device. The measurement result may use RSRP (SD-RSRP) of a discovery message transmitted by the candidate L2 U2NRelay UE. The identification information may be an identifier (ID).

[0133] Furthermore, an L2 U2N Remote UE having a serving L2 U2N Relay UE may use RSRP (SL-RSRP) measured in sidelink communication with the serving L2 U2N Relay UE as the measurement result. If SL-RSRP is not available for the measurement result, SD-RSRP may be used. The serving L2 U2N Relay UE may be an L2 U2N Relay UE that provides connectivity to a base station device to the L2 U2N Remote UE.

[0134] Next, the serving cell will be described. In a terminal device in an RRC connected state (RRC_CONNECTED) in which one serving cell is configured, the serving cell may be configured as one primary cell (PCell). Furthermore, in a terminal device in an RRC connected state in which multiple serving cells are configured, the serving cell may refer to a set of multiple cells (set of cell(s)) configured as one or more special cells (SpCells) and one or more all secondary cells (SCells). The SpCell may support PUCCH transmission and contention-based random access (CBRA). The PCell may be a cell used in the RRC connection establishment procedure when a terminal device in an RRC idle state (RRC_IDLE) transitions to an RRC connected state. The PCell may also be a cell used in the RRC connection re-establishment procedure in which the terminal device re-establishes the RRC connection. The PCell may also be a cell used in the random access procedure during handover. The SpCell may also be a cell used for purposes other than those mentioned above.

[0135] When a group of serving cells configured for a terminal device is composed of an SpCell and one or more SCells, it may be considered that carrier aggregation (CA) is configured for the terminal device. Also, for a terminal device in which CA is configured, a cell providing additional radio resources to the SpCell may refer to an SCell.

[0136] A cell group configured by a base station device for a terminal device will now be described. A cell group may be configured with one SpCell. A cell group may also be configured with one SpCell and one or more SCells. That is, a cell group may be configured with one SpCell and, optionally, one or more SCells. A cell group may also be expressed as a set of cells (set of cell(s)).

[0137] Dual Connectivity (DC) may be a technology for performing data communication using radio resources of cell groups configured by a first base station device (first node) and a second base station device (second node). When DC or MR-DC (described later) is performed, the cell group may be added from the base station device to the terminal device. To perform DC, the first base station device may add a second base station device. The first base station device may be called a master node (MN). Also, the cell group configured by the master node may be called a master cell group (MCG). The second base station device may be called a secondary node (SN). Also, the cell group configured by the secondary node may be called a secondary cell group (SCG). Note that the master node and the secondary node may be configured within the same base station device.

[0138] Furthermore, when DC is not configured, the cell group configured in the terminal device may be called an MCG. Furthermore, when DC is not configured, the SpCell configured in the terminal device may be a PCell. Furthermore, an NR in which DC is not configured may be called an NR standalone.

[0139] The UE 122 may receive a special cell (SpCell) configuration from the gNB 102. For example, an RRC reconfiguration (RRCReconfiguration) message may include a cell group configuration (an information element named CellGroupConfig), and the cell group configuration may include a special cell configuration (an information element named spCellConfig). An information element named spCellConfigDedicated included in the information element named spCellConfig may be an information element indicating a cell configuration dedicated to the UE 122 configured by this SpCellConfig. The information element named spCellConfigDedicated may be rephrased as SpCellConfigDedicated or SpCell dedicated configuration. Note that the information element named spCellConfigDedicated may include a BWP identifier parameter named firstActiveDownlinkBWP-Id (described later). Furthermore, the special cell configuration may include a reconfiguration with synchronization (an information element named reconfigurationWithSync). An information element named spCellConfigCommon included in an information element named reconfigurationWithSync may be used to configure cell-specific parameters of a serving cell (i.e., a special cell) of the UE 122. Note that to clearly indicate that a certain term is an information element, the term "IE" may be added. For example, a reconfiguration with Sync IE may be included in an RRC reconfiguration message, and the UE 122 that has received the RRC reconfiguration message may perform a reconfiguration with Sync (procedure) in accordance with the RRC reconfiguration message.

[0140] Next, we will explain Radio Link Monitoring (RLM) in Uu.

[0141] In the RRC connected state, the terminal device may perform RLM in an active BWP (described later) or a BWP designated as a BWP performing radio link monitoring. RLM may be performed based on a reference signal (e.g., CRS in E-UTRA, SSB / CSI-RS in NR) and a signal quality threshold. The reference signal may include an SSB. The signal quality threshold may be configured by the network or a default threshold may be used. SSB-based RLM may be performed based on an SSB associated with an initial DL BWP (described later). SSB-based RLM may be configured for the initial DL BWP and one or more DL BWPs including the SSB associated with the initial DL BWP. CSI-RS-based RLM may be performed for other DL BWPs.

[0142] In RLM, the terminal device may declare or detect a Radio Link Failure (RLF) based on the satisfaction of any of the following criteria (A) to (D): (A) The Radio Problem Timer, which starts based on in-sync and out-of-sync notifications from the PHY, expires; (B) The timer, which starts based on a measurement report for a specific measurement identifier being triggered while the Radio Problem Timer is running, expires; (C) The random access procedure fails; or (D) An RLC failure is detected.

[0143] A terminal device that detects RLF of the MCG may remain in the RRC connected state, select the best cell, and start a re-establishment procedure. Also, if DC is configured, a terminal device that declared RLF may remain in the RRC connected state and notify the network of the RLF. The terminal device may detect RLF of the MCG based on determining that any of the above criteria (A) to (D) is met in the PCell (for example, in the case of (A), the radio problem timer of the PCell expires, or in the case of (C), the random access procedure failed in the MAC of the MCG).

[0144] The terminal device may be configured with reference signals used for RLM by the network through RRC signaling. A radio link monitoring configuration (RadioLinkMonitoringConfig) may be used for the RRC signaling. The terminal device may perform RLM using one or more reference signals (referred to as RLM-RS) configured by the radio link monitoring configuration. Furthermore, if an RLM-RS is not specified, the terminal device may perform RLM using a default reference signal. The radio link monitoring configuration may be configured in the terminal device for each DL BWP. The radio link monitoring configuration may be configured for the DL BWP of the PCell and / or PSCell.

[0145] The PHY of the terminal device may notify the higher layer (RRC layer) that it is in sync when the condition for being in sync is met. The PHY of the terminal device may notify the higher layer (RRC, etc.) that it is out of sync when the condition for being out of sync is met.

[0146] The radio link monitoring configuration may include information indicating a monitoring purpose and identifier information indicating a reference signal. For example, the monitoring purpose may include a purpose of monitoring a radio link failure, a purpose of monitoring a beam failure, or both purposes. Furthermore, for example, the identifier information indicating the reference signal may include information indicating an SSB-Index of an SSB of a cell. Furthermore, for example, the identifier information indicating the reference signal may include information indicating an identifier linked to a channel state information reference signal (CSI-RS) configured in the terminal device.

[0147] If the terminal device is not provided with an RLM-RS and is provided with one or more TCI states for PDCCH reception, each including one or more CSI-RS, the terminal device shall perform some or all of the following (A) to (B): (A) If the activated TCI state for PDCCH reception includes only one reference signal, the terminal device shall use the reference signal provided in the activated TCI state for radio link monitoring; (B) If the activated TCI state for PDCCH reception includes two reference signals, the terminal device shall expect the QCL type of one reference signal to be set to type D and use the reference signal with the QCL type set to type D for radio link monitoring.

[0148] If multiple downlink BWPs are configured in a serving cell, the terminal device may perform RLM using a reference signal corresponding to the RLM-RS in the active downlink BWP. If multiple downlink BWPs are configured in a serving cell and the active downlink BWP does not provide an RLM-RS, the terminal device may perform RLM using the reference signal(s) provided in the activated TCI state for receiving a PDCCH in the CORESET of the active downlink BWP. The terminal device performing RLM may be expressed as the PHY of the terminal device assessing the radio link quality. If the measured radio link quality becomes worse than a configured threshold, the PHY may report out-of-sync to a higher layer (such as RRC).

[0149] A notification message in a U2N relay will now be described. A relay terminal device may transmit the notification message to a remote terminal device when it detects an RLF on the Uu interface, receives an RRC reconfiguration message including a synchronization-with-reconfiguration information element, starts cell reselection, detects an RRC connection failure (including an RRC connection rejection), T300 expires, or fails an RRC resumption procedure. The relay terminal device may include a notification type in the notification message. The notification type may be set to a different value depending on the reason for initiating transmission of the notification message, and may indicate, for example, a radio link failure in Uu, a radio link failure in a PC5 link, an RRC reconfiguration failure, a handover of a relay terminal device, a cell reselection of a relay terminal device, or another type. The remote terminal device receiving the notification message may initiate an RRC connection re-establishment procedure based on the RRC_CONNECCTED state, may notify an upper layer of the release of the PC5 unicast link based on the determination to release the PC5 RRC connection with the relay terminal device, or may consider that cell reselection has been initiated based on the notification type being relayUE-HO. The notification message may be a message named "NotificationMessageSidelink" or a message with another name. The notification type may be a message named "IndicationType" or a message with another name.

[0150] A UE 122 performing sidelink transmission performs transmission using a sidelink grant (SL grant). The sidelink grant may be dynamically received via a PDCCH transmitted by a base station apparatus, semi-persistently configured via RRC signaling transmitted by the base station apparatus, or automatically selected by a MAC entity of the terminal apparatus. Note that a transmission mode in which a sidelink grant is automatically selected by a MAC entity of the terminal apparatus may be referred to as mode 2, and a transmission mode in which a sidelink grant is dynamically allocated via a PDCCH transmitted by a base station apparatus and a transmission mode in which a sidelink grant is semi-persistently configured via RRC signaling received from the base station apparatus may be referred to as mode 1. Mode 1 and Mode 2 may each be a mode of sidelink resource allocation.

[0151] Based on the above description, various embodiments of the present invention will be described. Note that the above-described processes may be applied to processes that are omitted in the following description.

[0152] Fig. 5 is a block diagram showing the configuration of a terminal device (UE 122) in this embodiment. To avoid complicating the explanation, Fig. 5 shows only the main components closely related to this embodiment.

[0153] The UE 122 shown in FIG. 5 includes a receiver 500 that receives control information (SCI, MAC control element, RRC signaling, etc.), discovery messages, information including user data, etc. from other terminal devices, a processor 502 that performs processing according to parameters included in the received control information, etc., and a transmitter 504 that transmits the control information (SCI, MAC control element, RRC signaling, etc.), discovery messages, information including user data, etc. to other terminal devices. The receiver 500 may receive the control information (MAC control element, RRC signaling, etc.) and information including user data, etc. from the base station device (gNB 102). The transmitter 504 may transmit the control information (MAC control element, RRC signaling, etc.) and information including user data, etc. to the base station device (gNB 102). Furthermore, the processing unit 502 may include some or all of the functions of various layers (e.g., physical layer, MAC layer, RLC layer, PDCP layer, SDAP layer, RRC layer, PC5-S layer, discovery layer, and application layer). That is, the processing unit 502 may include some or all of a physical layer processing unit (PHY processing unit), MAC layer processing unit (MAC processing unit), RLC layer processing unit (RLC processing unit), PDCP layer processing unit (PDCP processing unit), SDAP processing unit (SDAP processing unit), RRC layer processing unit (RRC processing unit), PC5-S layer processing unit (PC5-S processing unit), discovery layer processing unit (Discovery processing unit), and application layer processing unit.

[0154] Fig. 6 is a block diagram showing the configuration of a base station device (gNB 102) in this embodiment. Note that, to avoid complicating the explanation, Fig. 6 shows only the main components closely related to this embodiment.

[0155] The base station apparatus shown in FIG. 6 includes a transmitter 604 that transmits control information (DCI, MAC CE, RRC signaling, etc.) to the UE 122, a processor 602 that generates control information (DCI, MAC CE, RRC signaling, etc.) and transmits it to the UE 122, causing the processor 502 of the UE 122 to process the control information, and a receiver 600 that receives the control information (UCI, MAC CE, RRC signaling, etc.) from the UE 122. The processor 602 may include some or all of the functions of various layers (e.g., the physical layer, MAC layer, RLC layer, PDCP layer, SDAP layer, RRC layer, and NAS layer). That is, the processor 602 may include some or all of the physical layer processing section, MAC layer processing section, RLC layer processing section, PDCP layer processing section, SDAP processing section, RRC layer processing section, and NAS layer processing section.

[0156] In a multi-hop U2N relay that provides connectivity to a base station device for a remote terminal device using multiple relay terminal devices, the multiple relay terminal devices may have the same functions as the above-mentioned U2N relay terminal device, or may have extended functions. The multiple relay terminal devices may maintain PC5-RRC connections with other adjacent relay terminal devices and remote terminal devices, or may maintain RRC connections with the base station device via other relay terminal devices.

[0157] FIG. 10 shows an example of an embodiment of one aspect of the present invention.

[0158] The UE 122 that communicates with the base station device makes a decision (step S1000) and operates based on the decision (step S1002).

[0159] In step S1000, the determination may be, for example, that the UE 122 satisfies one or more of the following conditions: (a) the UE 122 is acting as a remote terminal device; (b) the RRC state of the UE 122 is RRC_CONNECTED; (c) the RSRP of the received discovery message A is equal to or greater than a threshold; or (d) the RSRP of the received DCR message A is equal to or greater than a threshold.

[0160] In step S1002, the operation may be transmitting a discovery message B. Transmitting the discovery message B may be expressed as follows: the RRC layer configured in a higher layer (an application layer such as a discovery layer or a ProSe layer) to transmit a discovery message may configure a lower layer (a PHY layer) to perform sidelink resource allocation for transmitting the discovery message. Additionally or alternatively, in step S1002, the operation may be transmitting a DCR message B. Transmitting the DCR message B may be expressed as follows: the RRC layer configured in a higher layer (an application layer such as a discovery layer or a ProSe layer) to transmit a DCR message may configure a lower layer (a PHY layer) to perform sidelink resource allocation. The sidelink resource allocation may be a sidelink resource allocation for Mode 1 or Mode 2.

[0161] Furthermore, the determination in step S1000 may be, for example, that the UE 122 satisfies one or more of the following conditions: (a) The UE 122 is acting as a remote terminal device; (b) The UE 122 is not acting as a relay terminal device; (c) The RSRP of the received discovery message A is equal to or greater than a threshold; (d) The RSRP of the received DCR message A is equal to or greater than a threshold; or (e) The UE 122 is acting as a relay terminal device.

[0162] In step S1002, the operation may be, for example, including an information element indicating the RRC state of UE 122 in discovery message B. The discovery message B may be transmitted to terminal device A. Terminal device A may receive the discovery message B and consider UE 122 as a candidate relay terminal device based on the information element indicating the RRC state included in the discovery message B being set to RRC_CONNECTED. The terminal device A may report the candidate relay terminal device to a base station device. Additionally or alternatively, in step S1002, the operation may be, for example, transitioning the RRC state of UE 122 to RRC_CONNECTED.

[0163] The discovery message A may be a discovery message received by the UE 122, and the discovery message B may be a discovery message received by the UE 122. Transmitting the discovery message B based on receiving the discovery message A may be expressed as forwarding a discovery message, etc. The discovery message A may include the above-described information included in a discovery message. In addition, the discovery message A may include a hop count. In addition, the discovery message A may include a hop limit. In addition, the discovery message A may include a source L2 ID of the terminal device that transmitted the discovery message A as a source L2 ID. In addition, the discovery message A may include a destination L2 ID of the discovery message. The hop count may be an information element for counting the number of hops, and an initial value may be 1 or 0. The hop limit may be an information element indicating a limit on the number of hops for forwarding a discovery message. If the hop count is equal to or greater than the hop limit value, the discovery message may not be forwarded. The relationship between the hop count and the hop limit does not have to be as described above. For example, the initial value of the hop count may be set to the value of the hop limit, and the discovery message may not be forwarded when the hop count reaches 0. The discovery message B may include the same information as the discovery message, or some of the information may be updated. For example, the discovery message B may include a hop count set to the hop count included in the discovery message A plus 1. In addition, the discovery message B may include the source L2 ID of the UE 122 as the source L2 ID.

[0164] The discovery message A and the discovery message B may be discovery messages of Model A, i.e., announcement messages. Alternatively, the discovery message A and the discovery message B may be discovery messages of Model B, i.e., invitation messages or response messages. Alternatively, the discovery message A and the discovery message B may be discovery messages integrated into a DCR message.

[0165] In one example of this embodiment, a case where the multi-hop relay terminates at a base station device (multi-hop U2N relay) is shown, but UE122 may also perform similar operations when the multi-hop relay terminates at another terminal device (multi-hop U2U relay).

[0166] This example embodiment allows a multi-hop U2N relay to consider UEs with an RRC state of RRC_CONNECTED as candidate relay UEs.

[0167] In the above description, expressions such as "notified" and "indicated" may be interchangeable.

[0168] In the above description, expressions such as "link," "associate," and "link" may be interchangeable.

[0169] In addition, in the above description, expressions such as "included," "included," and "was included" may be used interchangeably.

[0170] In the above description, "the above-mentioned" may be replaced with "the above-mentioned."

[0171] In the above description, expressions such as "confirmed to be...", "is set to...", and "includes..." may be interchangeable.

[0172] Furthermore, in each example of processing or each example of processing flow in the above description, some or all of the steps may not be executed. Furthermore, in each example of processing or each example of processing flow in the above description, the order of the steps may be different. Furthermore, in each example of processing or each example of processing flow in the above description, some or all of the processing within each step may not be executed. Furthermore, in each example of processing or each example of processing flow in the above description, the order of the processing within each step may be different. Furthermore, in the above description, "doing B based on A being true" may be rephrased as "doing B." In other words, "doing B" may be executed independently of "A being true."

[0173] In the above explanation, "A may be replaced with B" may mean replacing A with B, as well as replacing B with A. Also, in the above explanation, when it is written that "C may be D" and "C may be E", it may also mean that "D may be E". Also, in the above explanation, when it is written that "F may be G" and "G may be H", it may also mean that "F may be H".

[0174] In the above explanation, if the conditions "A" and "B" are contradictory conditions, the condition "B" may be expressed as the "other" condition of the condition "A."

[0175] Furthermore, in the above explanation, "determining whether it is A or not" may mean "determining that it is A" or "determining that it is not A." "Determining that it is not A" may mean "not determining that it is A," and "determining that it is A" may mean "not determining that it is not A."

[0176] The program that runs on the device according to this embodiment may be a program that controls a central processing unit (CPU) or the like to make a computer function so as to realize the functions of this embodiment. The program or the information handled by the program is temporarily loaded into a volatile memory such as a random access memory (RAM) during processing, or stored in a nonvolatile memory such as a flash memory or a hard disk drive (HDD), and is read, modified, and written by the CPU as needed.

[0177] Note that a part of the device in the above-described embodiment may be realized by a computer. In this case, a program for realizing this control function may be recorded on a computer-readable recording medium, and the program recorded on the recording medium may be read and executed by a computer system. The "computer system" here refers to a computer system built into the device, including hardware such as an operating system and peripheral devices. Furthermore, the "computer-readable recording medium" may be any of a semiconductor recording medium, an optical recording medium, a magnetic recording medium, etc.

[0178] Furthermore, the term "computer-readable recording medium" may also include a medium that dynamically stores a program for a short period of time, such as a communication line when transmitting a program via a network such as the Internet or a communication line such as a telephone line, or a medium that stores a program for a certain period of time, such as a volatile memory within a computer system that serves as a server or client in such cases. The program may also be one that realizes part of the above-mentioned functions, or one that can realize the above-mentioned functions in combination with a program already stored in the computer system.

[0179] Furthermore, each functional block or feature of the device used in the above-described embodiments may be implemented or performed by an electrical circuit, typically an integrated circuit or multiple integrated circuits. The electrical circuit designed to perform the functions described herein may include a general-purpose processor, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or a combination thereof. The general-purpose processor may be a microprocessor, or alternatively, the processor may be a conventional processor, controller, microcontroller, or state machine. The general-purpose processor or each of the aforementioned circuits may be composed of digital circuits or analog circuits. Furthermore, if advances in semiconductor technology result in the emergence of integrated circuit technology that replaces current integrated circuits, integrated circuits based on that technology may also be used.

[0180] It should be noted that the present embodiment is not limited to the above-described embodiment. In the embodiment, an example of a device is described, but the present embodiment is not limited to this, and can be applied to terminal devices or communication devices such as stationary or non-movable electronic devices installed indoors or outdoors, for example, AV equipment, kitchen equipment, cleaning / washing equipment, air conditioning equipment, office equipment, vending machines, and other household appliances.

[0181] Although this embodiment has been described in detail above with reference to the drawings, the specific configuration is not limited to this embodiment and includes design modifications within the scope of the gist of this embodiment. Furthermore, this embodiment can be modified in various ways within the scope of the claims, and embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of this embodiment. Furthermore, configurations in which elements described in the above embodiment are substituted with elements that achieve the same effect are also included.

[0182] One aspect of the present invention can be used, for example, in a communication system, a communication device (e.g., a mobile phone device, a base station device, a wireless LAN device, or a sensor device), an integrated circuit (e.g., a communication chip), or a program.

[0183] 100 ng-eNB 102 gNB 110, 112, 114 Interface 122 UE 200, 700 PHY 202, 702 MAC 204, 704 RLC 206, 706 PDCP 208, 708 RRC 210 PC5-S 310, 710 SDAP 400 Discovery 500, 600 Receiver 502, 602 Processor 504, 604 Transmitter 712 NAS 800 SRAP

Claims

1. A terminal device that communicates with a base station device via a relay terminal device, comprising: a receiving unit that receives a first discovery message; and a processing unit, wherein the processing unit transmits a second discovery message based on determining that the RRC state of the terminal device is RRC_CONNECTED, and the first discovery message and the second discovery message are messages transmitted using SL-SRB4.

2. A method for a terminal device to communicate with a base station device via a relay terminal device, comprising: a step of receiving a first discovery message; and a step of transmitting a second discovery message based on determining that the RRC state of the terminal device is RRC_CONNECTED, wherein the first discovery message and the second discovery message are messages transmitted using SL-SRB4.

3. An integrated circuit implemented in a terminal device that communicates with a base station device via a relay terminal device, the integrated circuit having the functions of receiving a first discovery message and transmitting a second discovery message based on determining that the RRC state of the terminal device is RRC_CONNECTED, wherein the first discovery message and the second discovery message are messages transmitted using SL-SRB4.

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