Terminal device, method, and integrated circuit

Abstract

According to the present invention, a first terminal device capable of sidelink communication plays the role of a terminal device that relays communication between a second terminal device and a third terminal device, and a first packet delay budget (PDB) is reported to the second terminal device on the basis of determining that both of two conditions are satisfied. The two conditions are: (a) the most recent value of the first PDB reported to the second terminal device is different from the current value of the first PDB; and (b) a first timer is not running.

Description

Terminal device, method, and integrated circuit

[0001] This application claims priority to Japanese Patent Application No. 2023-162685, filed on September 26, 2023, 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, technical studies and standardization of E-UTRA (Evolved Universal Terrestrial Radio Access) have begun in 3GPP 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 v17.2.0,"Evolved Universal Terrestrial Radio Access (E-UTRA);Radio Resource Control (RRC);Protocol specifications" pp27-31, pp335-447, pp483-918, pp1062-1124, pp1142-11593GPP TS 38.321 v17.1.0, "NR;Medium Access Control (MAC) protocol specification" pp113-142, pp145-148, p2323GPP TS 38.213 v17.1.0, "NR; Physical layer procedures for control" pp14-203GPP TS 38.215 v17.1.0, "NR; Physical layer measurements" pp16-183GPP TS 23.304 v17.2.1, "Proximity based Services (ProSe) in the 5G System (5GS)" pp65-863GPP TS 38.300 v17.2.0, "NR; NR and NG-RAN Overall Description" pp148-157RP-221262, "Revised WID on NR sidelink relay enhancements"3GPP TR 23.700-33 v1.1.0, "Study on system enhancement for Proximity based Services (ProSe) in the 5G System (5GS);Phase 2" pp174-176, pp182-1833GPP TS 23.501 v17.2.0, " System architecture for the 5G System (5GS);Stage 2 " pp154-1683GPP TS 23.287 v17.2.0, "Architecture enhancements for 5G System (5GS) to support Vehicle-to-Everything (V2X) services" pp25-323GPP TS 37.324 v17.0.0, "E-UTRA and NR; Service Data Adaptation Protocol (SDAP) specification" pp9-16.

[0006] 3GPP is considering a technology called sidelink, which allows terminal devices to communicate directly with each other without going through the core network, as an extension technology of NR. In addition, research has begun on a technology (UE-to-UE relay) that allows other terminal devices to be added between terminal devices and supports communication between terminal devices.

[0007] One aspect of the present invention has been made in view of the above circumstances, and an object of the present invention is to provide a terminal device, a communication 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 provides the following: That is, one aspect of the present invention provides a first terminal device capable of sidelink communication, the first terminal device serving as a terminal device relaying communication between a second terminal device and a third terminal device, and including a processing unit and a transmitting unit, the processing unit notifying the second terminal device of a first packet delay budget (PDB) based on determining that both of two conditions are satisfied, the two conditions being: (a) a value of the first PDB last notified to the second terminal device is different from a current value of the first PDB, and (b) a first timer is not running.

[0009] Another aspect of the present invention is a method for a first terminal device capable of sidelink communication, wherein the first terminal device acts as a terminal device that relays communication between a second terminal device and a third terminal device, and includes a step of notifying the second terminal device of a first packet delay amount (PDB: Packet Delay Budget) based on determining that both of two conditions are satisfied, wherein the two conditions are: (a) the value of the first PDB last notified to the second terminal device is different from the current value of the first PDB, and (b) a first timer is not running.

[0010] Another aspect of the present invention is an integrated circuit mounted on a first terminal device capable of sidelink communication, wherein the first terminal device serves as a terminal device that relays communication between a second terminal device and a third terminal device, and performs a function of notifying the second terminal device of a first packet delay amount (PDB: Packet Delay Budget) based on determining that both of two conditions are satisfied, the two conditions being: (a) the value of the first PDB last notified to the second terminal device is different from the current value of the first PDB, and (b) a first timer is not running.

[0011] 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.

[0012] According to one aspect of the present invention, a terminal device, a method, and an integrated circuit can realize efficient communication control processing.

[0013] 1 is a schematic diagram of a communication system according to the present embodiment. 2 is a diagram of an example of a protocol configuration in NR sidelink communication according to the present embodiment. 3 is a diagram of an example of a protocol configuration in NR sidelink communication according to the present embodiment. 4 is a diagram of an example of a protocol configuration of a sidelink according to the present embodiment. 5 is a block diagram showing the configuration of a terminal device according to the present embodiment. 6 is a diagram of an example of a protocol configuration of a sidelink according to the present embodiment. 7 is a diagram of an example of a protocol configuration of a sidelink according to the present embodiment. 8 is an example of a process in the present embodiment.

[0014] Hereinafter, this embodiment will be described in detail with reference to the drawings.

[0015] In this embodiment, the names of the nodes and entities and the processes performed by the nodes and entities when the radio access technologies are NR and E-UTRA 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.

[0016] 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.

[0017] 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.

[0018] 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.

[0019] 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.

[0020] 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.

[0021] 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.

[0022] 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.

[0023] 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.

[0024] 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.

[0025] Groupcast transmission is characterized by (1) transmitting and receiving user traffic between UEs belonging to a sidelink group, and (2) supporting sidelink HARQ feedback.

[0026] Broadcast transmission is also characterized as (1) transmission and reception of user traffic between UEs on the sidelink.

[0027] 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.

[0028] Figure 2(A) 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 Figure 2(A), the control plane protocol stack for an SCCH using RRC 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 RRC (Radio Resource Control) 208, which is a radio resource control layer. Figure 2(B) 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.

[0029] 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.

[0030] The AS (Access Stratum) layer may be a layer including some or all of the PHY 200, MAC 202, RLC 204, SRAP 600, PDCP 206, SDAP 310, and RRC 208. The PC5-S 210 and Discovery 400, which will be described later, may be layers higher than the AS layer.

[0031] 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, SL RLC, PC5 RLC, etc., and other protocols may also be expressed as protocols for sidelink by adding "sidelink," "SL," or "PC5" to the beginning.

[0032] 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. Furthermore, 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. Furthermore, when distinguishing between E-UTRA protocols and NR protocols, PHY, MAC, RLC, PDCP, and RRC may 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.

[0033] 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.

[0034] 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.

[0035] 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. The base station apparatus and the terminal apparatus may also transmit and receive MAC Control Elements (MAC CEs) 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.

[0036] 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.

[0037] 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 also 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.

[0038] 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.

[0039] 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.

[0040] PSBCH (Physical Sidelink Broadcast CHannel) PSCCH (Physical Sidelink Control CHannel) PSSCH (Physical Sidelink Shared CHannel) PSFCH (Physical Sidelink Feedback CHannel)

[0041] The PSBCH may be used to broadcast system information required by the terminal device.

[0042] The PSCCH may be used to indicate resources and other transmission parameters for the PSSCH.

[0043] The PSSCH may be used to transmit data and control information related to HARQ / CSI feedback to other terminal devices.

[0044] The PSFCH may be used to carry HARQ feedback to other terminal devices.

[0045] 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.

[0046] 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).

[0047] 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.

[0048] 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.

[0049] 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.

[0050] 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.

[0051] 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.

[0052] 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.

[0053] 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).

[0054] 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.

[0055] 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 (SL-DRB). The SDAP may also store mapping rule information. The SDAP may also perform marking with a QoS flow identifier (QoS Flow 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.

[0056] 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.

[0057] 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.

[0058] 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.

[0059] 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.

[0060] 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.

[0061] 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 a discovery message type, a ProSe Application Code or a ProSe Restricted Code, and a 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.

[0062] 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.

[0063] 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.

[0064] 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.

[0065] 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.

[0066] A Direct Communication Request (DCR) message is also 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 by 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.

[0067] 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.

[0068] UE-to-UE relay may refer to a technology in which a source UE communicates with a destination UE via sidelink communication with a relay UE. The relay UE may have the function and / or role of forwarding (or relaying) data received from the source UE for the destination UE to the destination UE. The source UE, destination UE, and relay UE may be referred to by different names. For example, the source UE and destination UE may be referred to as remote UE or U2U Remote UE, and the relay UE may be referred to as U2U relay UE. The term UE-to-UE relay may also be referred to as U2U relay. The term remote UE may also be referred to as end UE.

[0069] 6 and 7 show examples of a control plane (CP) and user plane (UP) protocol stack in a Layer 2 (L2) UE-to-UE (U2U) relay. As shown in FIGS. 6 and 7, an SRAP 600 may be present. The SRAP 600 may be referred to as an SRAP layer (Sidelink Relay Adaptation Protocol layer), an SRAP layer, or the like, or a different name may be used. As shown in FIGS. 6 and 7, the PHY 200, MAC 202, RLC 204, and SRAP 600 may be associated between a remote UE and an L2 U2U relay UE, and between the L2 U2U relay UE and other remote UEs, respectively. Furthermore, the PDCP 206, RRC 208, and SDAP 310 may be associated between a remote UE and other remote UEs. As shown in FIG. 2, a PC5-S 210 may be used instead of the RRC 208 to control the PC5 connection between the remote UE and other remote UEs (not shown). In a protocol stack for Layer 3 (L3) UE-to-UE relay, the PHY 200, MAC 202, RLC 204, PDCP 206, RRC 208, and SDAP 210 may be associated between the remote UE and the U2U relay UE, and between the U2U relay UE and other remote UEs, respectively, and the SRAP 600 may not be configured (not shown). In the L3 U2U relay, a layer higher than the SDAP may have a function for transmitting data received over a Uu link over a PC5 link. The SRAP layer may be included in the AS layer.

[0070] 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 exist above the RLC sublayer for the control and user planes of the PC5 interface, and below the PDCP sublayer for the control and user planes of the PC5 interface. The SRAP sublayer on the PC5 interface may be used for bearer mapping, such as mapping between SL-DRBs and RLC channels. In an L2 U2U Relay UE, the SRAP sublayer may include one SRAP entity on the PC5 interface between the source UE and the relay UE, and a separate collocated SRAP entity on the PC5 interface between the relay UE and the destination UE. In an L2 U2U Remote UE, the SRAP sublayer may include only one SRAP entity on one PC5 interface. The SRAP entity associated between the Remote UE and the Relay UE via the PC5 interface may be specifically referred to as a PC5-SRAP. Each SRAP entity may have a transmitter and a receiver. On the PC5 interface, the transmitter of the SRAP entity of the L2 U2U Remote UE may be associated with the receiver of the SRAP entity of the L2 U2U Relay UE, and the receiver of the SRAP entity of the L2 U2U Remote UE may be associated with the transmitter of the SRAP entity of the L2 U2U Relay UE.

[0071] The SRAP entity may also have a function to forward data, a function to determine the UE ID field and the bearer ID field of the SRAP header to be added to the data packet, a function to determine the egress link, a function to determine the egress RLC channel, and other functions.

[0072] Furthermore, when a remote UE transmits sidelink data to another remote UE, the remote UE may be referred to as a source UE, and the other remote UE may be referred to as a destination UE. Similarly, in the reverse case, when another remote UE transmits sidelink data to a remote UE, the other remote UE may be referred to as a source UE, and the remote UE may be referred to as a destination UE. Note that the source UE may be referred to as a source remote UE, or simply as a remote UE, or these terms may be interchangeable. The destination UE may be referred to as a destination remote UE, or simply as a remote UE, or target UE, or these terms may be interchangeable. The source UE and the destination UE may be identified by different names, or may be referred to as a U2U source UE, a U2U destination UE, or the like to clarify that they are terminals performing U2U relay. Furthermore, to clarify that communication is performed via an L2 U2U relay, the UEs may be referred to as, for example, an L2 U2U source UE or an L2 U2U destination UE, and similarly, to clarify that communication is performed via an L3 U2U relay, the UEs may be referred to as, for example, an L3 U2U source UE or an L3 U2U destination UE. Not only when either a remote UE or another remote UE transmits sidelink data, but also when forming a U2U relay pair (a pair of one remote UE, one relay UE, and another remote UE), a UE that first transmits a discovery message other than the U2U relay UE may be referred to as a source UE, and a UE that is neither a source UE nor a U2U relay UE in the U2U relay may be referred to as a destination UE, or names such as source UE and destination UE may be used simply to distinguish between two remote UEs.

[0073] Furthermore, the UE may transmit a discovery message and / or a direct communication request message to perform U2U relay. For example, to select a relay UE for U2U relay, the source UE may transmit a discovery message or a direct communication request message. In this case, discovery may be Model B discovery. A UE (a relay UE candidate) that receives a discovery message or a direct communication request message transmitted from the source UE may transmit a discovery message or a direct communication request message to the destination UE. Furthermore, the UE (a relay UE candidate) may transmit a discovery message and / or a direct communication request message to the source UE. In this case, discovery may be Model A discovery.

[0074] In the sidelink, the Reference Signal Received Power (RSRP) measured by the UE may be, for example, the following RSRPs: (a) PSBCH RSRP, (b) PSSCH RSRP, and (c) PSCCH RSRP.

[0075] 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 transmitting the DMRS associated with the PSSCH carrying the discovery message.

[0076] In addition to the 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).

[0077] 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]).

[0078] There are two resource allocation modes for NR sidelink communication: Mode 1, in which the UE performs sidelink transmission using resources scheduled by the base station, and Mode 2, in which the UE automatically selects resources for sidelink transmission. In Mode 1, the UE must be RRC_CONNECTED. In Mode 2, the UE can perform sidelink transmission regardless of the RRC state or whether it is inside or outside NG-RAN. In Mode 2, the UE automatically selects resources available for sidelink transmission from one or more resource pools configured before the sidelink transmission.

[0079] The operation of a transmitting SDAP entity in sidelink communication is described below. When an SDAP SDU for a certain PC5 QoS flow is received from a higher layer (e.g., the application layer), if a mapping rule between a PC5 QoS flow and an SL-DRB for the PC5 QoS flow is not stored, the transmitting SDAP entity maps the SDAP SDU to a default SL-DRB. If a mapping rule between a PC5 QoS flow and an SL-DRB for the PC5 QoS flow is stored, the transmitting SDAP entity maps the SDAP SDU to an SL-DRB according to the mapping rule. Furthermore, if the RRC configures the SL-DRB to which the SDAP SDU is mapped so that an SDAP header exists, the transmitting SDAP entity constructs an SL SDAP data PDU with an SDAP header. If the RRC configures the SL-DRB to which the SDAP SDU is mapped so that an SDAP header exists, the transmitting SDAP entity constructs an SL SDAP data PDU without an SDAP header. The transmitting SDAP entity then submits the constructed SL SDAP PDU to a lower layer (e.g., the PDCP layer).

[0080] The operation of a receiving SDAP entity in sidelink communication will be described. When an SDAP data PDU for a certain PC5 QoS flow is received from a lower layer (such as the PDCP layer), the receiving SDAP entity extracts an SDAP SDU from the SL SDAP data PDU with an SDAP header if the SL-DRB that received the SL SDAP data PDU is configured by RRC to have an SDAP header. Alternatively, if the SL-DRB that received the SL SDAP data PDU is not configured by RRC to have an SDAP header, the receiving SDAP entity extracts an SDAP SDU from the SL SDAP data PDU without an SDAP header. The receiving SDAP entity then passes the extracted SDAP SDU to a higher layer (such as the application layer).

[0081] Next, the mapping between PC5 QoS flows and SL-DRBs will be described. When RRC configures the mapping between PC5 QoS flows and SL-DRBs for a PC5 QoS flow, the SDAP entity generates an end marker control PDU for the PC5 QoS flow, maps the end marker control PDU to the default SL-DRB, and submits the end marker control PDU to a lower layer (such as the PDCP layer) if (1) the SDAP entity has already been established for unicast NR sidelink communication, (2) a mapping rule for SL-DRBs to PC5 QoS flows is not stored, and (3) a default SL-DRB is configured. Furthermore, when RRC configures a mapping between a PC5 QoS flow and an SL-DRB for a PC5 QoS flow, the SDAP entity generates an end marker control PDU for unicast NR sidelink communication if (1) the stored mapping rule between the PC5 QoS flow and the SL-DRB differs from the configured mapping rule between the PC5 QoS flow and the SL-DRB, and (2) the RRC configures an SL SDAP header to exist in the SL-DRB according to the stored mapping rule. The SDAP entity also stores the mapping rule between the PC5 QoS flow and the SL-DRB configured for the PC5 QoS flow. When RRC releases the mapping rule between the PC5 QoS flow and the SL-DRB for a PC5 QoS flow, the SDAP entity deletes the mapping rule. Also, when the RRC indicates that a certain SL-DRB is to be released, the SDAP entity releases all mapping rules between the PC5 QoS flow and the SL-DRB associated with the SL-DRB.

[0082] The header attached to an SL SDAP data PDU may include information indicating that the SDAP PDU is an SDAP data PDU and information indicating the identifier of the PC5 QoS flow to which the SL SDAP data PDU belongs (PQFI or PFI: PC5 QoS flow ID). An end marker control PDU may be a control PDU used by an SDAP entity to indicate that mapping of SDAP SDUs of the PC5 QoS flow indicated by the PQFI to the SL-DRB on which the end marker control PDU is transmitted is terminated. The header attached to an end marker control PDU may include information indicating that the SDAP PDU is an SDAP control PDU and the PQFI.

[0083] Furthermore, a PC5 QoS flow is the finest granularity of QoS forwarding processing in the sidelink, and all traffic (data) mapped to the same PC5 QoS flow receives the same forwarding processing (scheduling policy, queue management policy, rate shaping policy, RLC configuration, etc.). Different PC5 QoS flows are required to provide different forwarding processing. A PC5 QoS flow is also associated with a PC5 QoS rule and PC5 QoS parameters. PC5 QoS parameters include PQI (PC5 5QI (5G QoS Identifier)), PC5 Flow Bit Rates, PC5 Link Aggregated Bit Rates, Range, Default Value, etc. The PQI is used as a reference for PC5 QoS characteristics, i.e., parameters that control the QoS forwarding processing of packets via PC5. The PC5 QoS characteristics include resource type, priority level, packet delay budget (PDB), packet error rate (PER), averaging window, and maximum data burst volume. Here, the PDB indicates the upper limit of packet delay time between a transmitting UE and a receiving UE on the PC 5. Furthermore, the UE may associate traffic (data) with a QoS flow based on a QoS rule.

[0084] A UE that receives a packet from the application layer determines whether a PC5 QoS flow matching the packet exists based on the PC5 QoS rules. If it determines that no PC5 QoS flow exists, it determines PC5 QoS parameters according to requirements provided by the application layer, and if no requirements exist, it determines PC5 QoS parameters according to the mapping between service types and PC5 QoS parameters. After determining the PC5 QoS parameters, if no PC5 QoS flow satisfies the determined PC5 QoS parameters, the UE creates a new PC5 QoS flow that satisfies the determined PC5 QoS parameters, assigns a PFI and PC5 QoS rules to the new PC5 QoS flow, and if a PC5 QoS flow that satisfies the determined PC5 QoS parameters exists, it updates the PC5 packet filter set of such PC5 QoS flow.

[0085] 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.

[0086] 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.

[0087] 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. In addition, the processor 502 may include some or all of the functions of various layers (e.g., a physical layer, a MAC layer, an RLC layer, a PDCP layer, a SRAP layer, an SDAP layer, an RRC layer, a PC5-S layer, a discovery layer, and an application layer). That is, the processing unit 502 may include some or all of a physical layer processing unit (PHY processing unit), a MAC layer processing unit (MAC processing unit), an RLC layer processing unit (RLC processing unit), a PDCP layer processing unit (PDCP processing unit), a SRAP layer processing unit (SRAP processing unit), an SDAP layer processing unit (SDAP processing unit), an RRC layer processing unit (RRC processing unit), a PC5-S layer processing unit (PC5-S processing unit), a discovery layer processing unit (Discovery processing unit), and an application layer processing unit. Note that a ProSe layer, a V2X layer, etc. may be included as part of the application layer, or an application layer that provides services to the ProSe layer, V2X layer, etc. may exist above the ProSe layer or V2X layer.

[0088] An example of an embodiment of the present invention will be described with reference to FIG.

[0089] In step S800, the UE 122 capable of sidelink communication makes a determination based on data received from a higher layer, and in step S802, transmits first information to a first terminal device based on the determination.

[0090] In step S800, the data may be an SDAP SDU for a certain PC5 QoS flow. Also, in step S800, the UE 122 may make some or all of the following determinations: (Ca) A mapping rule between the PC5 QoS flow and an SL-DRB exists. (Cb) The UE 122 is acting as an L2 U2U remote UE.

[0091] If it is determined that the condition (Ca) is not satisfied but the condition (Cb) is satisfied, the UE 122 may transmit the first information, and if it is determined that both the conditions (Ca) and (Cb) are satisfied, or if it is determined that the condition (Cb) is not satisfied, the UE 122 may not transmit the first information in step S802. Note that the first information may include, for example, some or all of the following information: (Ia) Information identifying the PC5 QoS flow (e.g., PFI or PQFI) (Ib) Mapping rule between the PC5 QoS flow and the SL-DRB set by the UE 122 (Ic) PQI mapped to the PC5 QoS flow (Id) Identifier for identifying the UE 122 (Ie) Mapping rule between the SL-DRB and the RLC channel (PC5 (relay) RLC channel) of the UE 122

[0092] For example, the first terminal device that has received the first information may map the SL-DRB to an RLC channel in consideration of a mapping rule between the PC5 QoS flow and the SL-DRB. The SL-DRB may be an End-to-End (E2E) SL-DRB that is terminated at a second terminal via a first terminal device from the UE 122, and the RLC channel may be an RLC channel used by the first terminal device to transfer data from the UE 122 to the second terminal device. Furthermore, the RLC channel may be called a PC5 Relay RLC Channel or another name. In addition, when the first terminal device is unable to map the SL-DRB and the RLC channel in consideration of the mapping rule between the PC5 QoS flow and the SL-DRB, i.e., when it determines that transfer satisfying QoS is not possible, it may transmit to UE 122 information indicating that mapping between the SL-DRB and the RLC channel is not possible, and when the first terminal device has mapped the SL-DRB and the RLC channel in consideration of the mapping rule between the PC5 QoS flow and the SL-DRB, i.e., when it determines that transfer satisfying QoS is possible, it may transmit to UE 122 information indicating that mapping between the SL-DRB and the RLC channel has been performed, or may transmit to UE 122 information indicating whether mapping between the SL-DRB and the RLC channel has been performed. In addition, the first terminal device that has performed mapping between the SL-DRB and the RLC channel may transmit data including information identifying the SL-DRB to a second terminal device via the RLC channel.

[0093] The first terminal device may determine whether or not the mapping between the SL-DRB and the RLC channel can be performed in consideration of the mapping rule between the PC5 QoS flow and the SL-DRB, based on path quality between the first terminal device and the UE 122 and between the first terminal device and the second terminal device. The path quality may be an SL CBR (Sidelink Channel Busy Ratio), an RSRP (Reference Signal Received Power), an SL path loss, a modulation and coding scheme (MCS) used for sidelink transmission, or other information.

[0094] The UE 122 may set a mapping between the PC5 QoS flow and the SL-DRB, and may also set a mapping rule between the SL-DRB and an RLC channel (PC5 Relay RLC channel) of the UE 122. When the mapping rule between the SL-DRB and the RLC channel is set, the UE 122 may transmit a setting regarding the mapping rule between the SL-DRB and the RLC channel to the first terminal device.

[0095] Furthermore, for example, the first terminal device that has received the first information may transmit a mapping rule between an SL-DRB and a PC5 QoS flow that satisfies QoS, i.e., an SDAP layer configuration, to the UE 122. Additionally, the first terminal device may transmit a mapping rule between the SL-DRB and the RLC channel, i.e., an SRAP layer configuration, to the UE 122. The UE 122 that has received the SDAP layer configuration of the UE 122 may configure the SDAP layer according to the SDAP layer configuration and transmit data for the PC5 QoS flow according to the mapping rule. The PC5 QoS flow may be mapped to an SL-DRB already configured in the UE 122, or a new SL-DRB may be established for the PC5 QoS flow and the PC5 QoS flow may be mapped to the established SL-DRB. The SDAP layer configuration and / or the SRAP layer configuration may be transmitted to the UE 122 by an RRC message (e.g., RRCReconfigurationSidelink).

[0096] Furthermore, the first terminal device that has received the first information may configure a remaining PDB in the RLC channel or logical channel to which the SL-DRB is mapped, based on a mapping rule between the PC5 QoS flow and the SL-DRB. Additionally, the remaining PDB may be configured based on a PC5 QoS rule or PC5 QoS parameters associated with the PC5 QoS flow, or based on the number of relay nodes (U2U relay UEs) present between the UE 122 and the second terminal device. The first terminal device may select resources to be used for sidelink transmission taking the remaining PDB into consideration.

[0097] Furthermore, when transmitting the data to a first terminal device, the UE 122 may transmit information regarding a remaining PDB associated with the data. For example, the information regarding the remaining PDB may be attached to the data as an information element of the SRAP layer, or may be included in a transport block including the data as a MAC CE. The first terminal device that has received the information regarding the remaining PDB may determine a remaining PDB to use in transmitting the data based on the information regarding the remaining PDB.

[0098] In addition, the UE 122 may transmit and receive information about the PC5 QoS flow to be added with the peer terminal device when establishing or modifying the PC5 unicast link (and Layer-2 link) with the peer terminal device. The information about the PC5 QoS flow may be, for example, information such as the PFI of the PC5 QoS flow to be added, PC5 QoS parameters (including at least PQI) corresponding to the PFI, PC5 QoS characteristics, and service type. In addition, the UE 122 may determine the PC5 QoS by negotiating with the peer terminal device.

[0099] For example, the first terminal device may determine a PC5 QoS parameter (PC5-QoS-1) at a first hop (i.e., a path between the UE 122 and the first terminal device) and a PC5 QoS parameter (PC5-QoS-2) at a second hop (i.e., a path between the first terminal device and the second terminal device) from PC5 QoS parameters corresponding to an E2E QoS flow or an E2E SL-DRB received from the UE 122. In this case, for example, the first terminal device may determine PC5-QoS-1 and PC5-QoS-2 based on determining that it has received PC5 QoS parameters corresponding to the E2E QoS flow or an E2E SL-DRB. The PC5-QoS-1 and PC5-QoS-2 may be determined for each E2E QoS flow or E2E SL-DRB. In this embodiment, the PC5 QoS parameter may be referred to as a PC5 QoS characteristic. That is, the PC5 QoS parameter may be a PDB, a PER, or other PC5 QoS characteristic or PC5 QoS parameter. For example, if the PC5 QoS parameter is a PDB, the first terminal device may notify the UE 122 of the PDB at the first hop. The UE 122 may determine the RLC layer configuration at the first hop and perform sidelink transmission at the first hop based on the PDB at the first hop. Transmission and reception of PC5 QoS parameters, including the PDB example described above, may be performed by AS layer signaling (e.g., a PC5 RRC message) or non-AS layer signaling (e.g., a ProSe layer message, a PC5-S message, etc.). Furthermore, the first terminal device may notify the UE 122 of the PC5-QoS-1 based on receiving PC5 QoS parameters corresponding to the E2E QoS flow or E2E SL-DRB.

[0100] The first terminal device may also update the PC5-QoS-1. For example, the first terminal device may update the PC5-QoS-1 based on, for example, the start of sidelink communication with a UE other than the UE 122 and the second terminal device, a change in the downlink RSRP measured by the first terminal device, a change in the CBR measured by the first terminal device, a change in the RSRP between the UE 122 or the RSRP between the UE 122 and the second terminal device, application requirements of the first terminal device (such as power-saving operation or communication speed restrictions), etc. The first terminal device may also notify the UE 122 of the updated PC5-QoS-1. Note that the transmission and reception of the PC5 QoS parameters may be performed by AS layer signaling (e.g., a PC5 RRC message) or non-AS layer signaling (e.g., a ProSe layer message, a PC5-S message, etc.). Note that the first terminal device may update the PC5-QoS-1 and the PC5-QoS-2.

[0101] Upon receiving the updated PC5-QoS-1, the UE 122 may perform some or all of the following operations: (a) Determine the mapping between the QoS flow associated with the updated PC5-QoS-1 and the SL-DRB, i.e., the SRAP layer configuration; (b) Notify the updated PC5-QoS-1 to a higher layer (for example, if the PC5-QoS-1 is received in a PC5 RRC message, this may be an application (ProSe, V2X, etc.) layer, etc.); (c) Determine the mapping between the SL-DRB to which the QoS flow associated with the updated PC5-QoS-1 is mapped and the RLC channel, i.e., the SRAP layer configuration; (d) Determine the RLC channel configuration of the SL-DRB to which the QoS flow associated with the updated PC5-QoS-1 is mapped; (e) Determine the remaining PDB based on the updated PC5-QoS-1; and (f) Modify the U2U relay UE.

[0102] The first terminal device may notify the UE 122 of the PC5-QoS-1 for each QoS flow, in which case, for example, a set of PQFI and PC5-QoS-1 may be notified to the UE 122. The first terminal device may also notify the UE 122 of the PC5-QoS-1 for each SL-DRB, in which case, for example, a set of SL-DRB ID and PC5-QoS-1 may be notified to the UE 122. The first terminal device may also notify the UE 122 of the PC5-QoS-1 for each RLC channel (or logical channel), in which case, for example, a set of a sidelink logical channel identifier (SL LCID) and PC5-QoS-1 may be notified to the UE 122.

[0103] In addition, if the first terminal device determines that it is unable to perform sidelink transmission that satisfies PC5-QoS-2, it may notify the UE 122 that it is unable to perform sidelink transmission that satisfies PC5-QoS-2.

[0104] The first terminal device may also notify the above-mentioned PC5-QoS-1 based on determining that some or all of the following conditions are met: (a) PC5-QoS-1 for a certain E2E PC5 QoS flow has not been notified, (b) PC5-QoS-1 for a certain E2E PC5 QoS flow currently is different from PC5-QoS-1 for the E2E PC5 QoS flow notified previously, or (c) The first timer is not running.

[0105] The first terminal device may start or restart the first timer based on a determination that some or all of the conditions are satisfied, and notify the UE 122 of the PC5-QoS-1. For example, when a PDB is used as PC5-QoS-1, the first terminal device may start the first timer from a set value and notify the UE 122 of the first PDB based on a determination that the condition (a (the first PDB for a certain E2E PC5 QoS flow has not been notified)) is satisfied, or may restart the first timer from a set value and notify the UE 122 of the first PDB based on a determination that both or either of the conditions (b (the value of the first PDB for a certain E2E PC5 QoS flow at present is different from the value of the first PDB for the E2E PC5 QoS flow that was previously notified)) and (c (the first timer is not running)) are satisfied. The value of the first timer may be set to a default value or may be set by a PC5 RRC message received from the UE 122. Note that the first terminal device may notify the UE 122 of the PC5-QoS-1 regardless of the condition.

[0106] The first terminal device may be an L2 U2U relay UE, and the UE 122 and the second terminal device may be L2 U2U remote UEs. The UE 122 may communicate with the second terminal device via the first terminal device, and the UE 122 may communicate with the second terminal device via the first terminal device and a plurality of other terminal devices. The other plurality of terminal devices may have a function to perform the same operation as the first terminal device.

[0107] In each embodiment, the first terminal device, the second terminal device, and the other multiple terminal devices may be terminal devices capable of sidelink communication, similar to UE122, and may have a configuration including a receiving unit, a processing unit, and a transmitting unit, or may be referred to by other names.

[0108] Conventional PC5 QoS processing in NR does not assume that data will be relayed by the UE, and if data is relayed, there is a possibility that data transmission that satisfies PC5 QoS cannot be performed. This invention enables transmission that takes into account end-to-end PC5 QoS even when data is relayed by the UE. Furthermore, appropriate QoS processing can be performed by dynamically considering QoS for each hop.

[0109] In the above description, expressions such as "notified" and "indicated" may be interchangeable.

[0110] In the above description, expressions such as "link," "associate," and "link" may be interchangeable.

[0111] In addition, in the above description, expressions such as "included," "included," and "was included" may be used interchangeably.

[0112] In the above description, "the above-mentioned" may be replaced with "the above-mentioned."

[0113] In the above description, expressions such as "confirmed to be...", "is set to...", and "includes..." may be interchangeable.

[0114] 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, expressions such as "doing B based on A" may be rephrased as "doing B." In other words, "doing B" may be executed independently of "A."

[0115] 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".

[0116] 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."

[0117] 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.

[0118] 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.

[0119] 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.

[0120] 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.

[0121] 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.

[0122] 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.

[0123] One aspect of the present invention is suitable for use in a communication device and a communication method.

[0124] 100 ng-eNB 102 gNB 110, 112, 114 Interface 122 UE 200 PHY 202 MAC 204 RLC 206 PDCP 208 RRC 210 PC5-S 310 SDAP 400 Discovery 500 Receiver 502 Processor 504 Transmitter 600 SRAP

Claims

1. A first terminal device capable of sidelink communication, comprising: a processing unit; and a transmitting unit, wherein the processing unit determines whether a packet delay budget (PDB) value last notified to a second terminal device is different from a current value of the PDB, and the transmitting unit notifies the second terminal device of the current value of the PDB based on the determination that the PDB value last notified to the second terminal device is different from the current value of the PDB.

2. A method of a first terminal device capable of sidelink communication, comprising the steps of: determining whether a packet delay budget (PDB) value last notified to a second terminal device is different from a current PDB value; and notifying the second terminal device of the current PDB value based on a determination that the PDB value last notified to the second terminal device is different from the current PDB value.

3. An integrated circuit mounted on a first terminal device capable of sidelink communication, the integrated circuit having: a function for determining whether the value of the packet delay budget (PDB) last notified to a second terminal device is different from the current value of the PDB; and a function for notifying the second terminal device of the current value of the PDB based on a determination that the value of the PDB last notified to the second terminal device is different from the current value of the PDB.

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