Method and apparatus for reporting channel state information for sidelink communication

Abstract

A method and apparatus for reporting channel state information for sidelink communication are disclosed. An operation method of a first terminal comprises the steps of: transmitting information indicating a delay threshold value of an SL CSI report to a second terminal; sending an SCI including the CSI request information to a second terminal; and performing a monitoring operation to receive the SL CSI of the second terminal within a time period corresponding to the delay threshold value from a transmission time of the CSI request information.

Description

[0001] This application is a divisional application of the Chinese patent application with the application date of February 25, 2021, application number 202180014006.2, and invention name “Method and device for reporting channel state information of side link communication”. Technical Field

[0002] The present disclosure relates to a sidelink communication technology, and more particularly, to a technology for reporting channel state information of sidelink communication. Background Art

[0003] To handle the dramatic increase in wireless data following the commercialization of fourth-generation (4G) communication systems (e.g., Long Term Evolution (LTE) communication systems and LTE-Advanced (LTE-A) communication systems), fifth-generation (5G) communication systems (e.g., New Radio (NR) communication systems) are being considered, using frequency bands of 4G communication systems (e.g., bands below 6 GHz) and higher frequency bands than 4G communication systems (e.g., bands above 6 GHz). 5G communication systems can support enhanced mobile broadband (eMBB) communication, ultra-reliable and low-latency communication (URLLC), and massive machine type communication (mMTC).

[0004] 4G communication systems and 5G communication systems support vehicle-to-everything (V2X) communication (e.g., sidelink communication). V2X communication supported in cellular communication systems such as 4G communication systems and 5G communication systems may be referred to as "cellular-V2X (C-V2X) communication." V2X communication (e.g., C-V2X communication) may include vehicle-to-vehicle (V2V) communication, vehicle-to-infrastructure (V2I) communication, vehicle-to-pedestrian (V2P) communication, vehicle-to-network (V2N) communication, and the like.

[0005] In a cellular communication system, V2X communication (e.g., C-V2X communication) can be performed based on a sidelink communication technology (e.g., a proximity-based service (ProSe) communication technology, a device-to-device (D2D) communication technology, etc.). For example, a sidelink channel can be established for vehicles participating in V2V communication, and the sidelink channel can be used for communication between vehicles. Sidelink communication can be performed using configured grant (CG) resources. CG resources can be periodically configured, and periodic data (e.g., periodic sidelink data) can be sent using the CG resources.

[0006] On the other hand, sidelink communication can be performed based on a broadcast scheme, a multicast scheme, and / or a unicast scheme. In particular, sidelink communication based on a unicast scheme may require channel state information between terminals. Summary of the Invention

[0007] Technical issues

[0008] An object of the present disclosure to solve the above-mentioned problem is to provide a method and apparatus for reporting channel state information of sidelink communication.

[0009] Technical Solution

[0010] According to a first exemplary embodiment of the present disclosure for achieving the above-mentioned purpose, an operating method of a first terminal may include the following steps: sending information indicating a delay bound value of a sidelink (SL) channel state information (CSI) report to a second terminal; sending sidelink control information (SCI) including CSI request information to the second terminal; and performing a monitoring operation within a time period corresponding to the delay bound value to receive the SL CSI of the second terminal, starting from the time when the CSI request information is sent.

[0011] The operation method may further include, when no SL CSI of the second terminal is received within the time period, retransmitting the CSI request information.

[0012] When retransmitting the CSI request information, the reset delay limit value may be used to replace the delay limit value, and the reset delay limit value may be greater than or less than the delay limit value.

[0013] The delay limit value may be set specifically for the side link.

[0014] The delay limit value can be set in units of time slots.

[0015] The delay limit value may be a time offset from the time of sending the CSI request information.

[0016] The delay limit value may be set independently of the type of the SL CSI, and the type of the SL CSI may vary according to information contained in the SL CSI.

[0017] Among them, SL CSI may include a channel quality indicator (CQI) and a rank indicator (RI).

[0018] Among them, SL CSI can be received on the physical sidelink shared channel (PSSCH).

[0019] According to a second exemplary embodiment of the present disclosure for achieving the above-mentioned purpose, an operating method of a second terminal may include the following steps: receiving a radio resource control (RRC) message including information indicating a delay limit value of a sidelink (SL) channel state information (CSI) report from a first terminal; receiving sidelink control information (SCI) including CSI request information from the first terminal; generating SL CSI by performing a measurement operation based on a reference signal received from the first terminal; and sending SL CSI to the first terminal within a time period corresponding to the delay limit value, starting from the time when the CSI request information is received.

[0020] When the time period ends, the SL CSI may not be sent to the first terminal.

[0021] The delay limit value may be set specifically for the side link.

[0022] The delay limit value may be set in units of time slots and may start from the time when the CSI request information is received.

[0023] The delay limit value may be set independently of the type of the SL CSI, and the type of the SL CSI may vary according to information contained in the SL CSI.

[0024] Among them, SL CSI may include a channel quality indicator (CQI) and a rank indicator (RI).

[0025] According to a third exemplary embodiment of the present disclosure for achieving the above-mentioned objectives, a first terminal may include: a processor; and a memory configured to store at least one instruction executed by the processor. The at least one instruction is executed to: send a radio resource control message (RRC message) including information indicating a delay limit value for a sidelink (SL) channel state information (CSI) report to a second terminal; send sidelink control information (SCI) including CSI request information to the second terminal; and perform a monitoring operation to receive the SL CSI of the second terminal within a time period corresponding to the delay limit value starting from the time the CSI request information is sent.

[0026] In which, at least one instruction can be further executed to retransmit the CSI request information when the SLCSI of the second terminal is not received within a time period, and when the CSI request information is retransmitted, the reset delay limit value can be used to replace the delay limit value, and the reset delay limit value can be greater than or less than the delay limit value.

[0027] The delay bound value may be set specifically for the sidelink and may be used for unicast sidelink communications.

[0028] The delay limit value may be set in units of time slots and may start from the time when the CSI request information is sent.

[0029] Among them, SL CSI may include a channel quality indicator (CQI) and a rank indicator (RI).

[0030] Beneficial effects

[0031] According to an exemplary embodiment of the present disclosure, a transmitting terminal may transmit information required for measuring sidelink (SL) channel state information (CSI) to a receiving terminal. The receiving terminal may measure the SL CSI based on the information received from the transmitting terminal and may transmit the SL CSI to the transmitting terminal. In particular, the SL CSI may be transmitted within a preconfigured time period. The transmitting terminal may perform sidelink communication with the receiving terminal based on the SL CSI. Consequently, the performance of sidelink communication may be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 is a conceptual diagram illustrating a V2X communication scenario.

[0033] Figure 2 is a conceptual diagram illustrating an exemplary embodiment of a cellular communication system.

[0034] Figure 3 is a conceptual diagram illustrating an exemplary embodiment of a communication node constituting a cellular communication system.

[0035] Figure 4is a block diagram illustrating an exemplary embodiment of a user plane protocol stack of a UE performing sidelink communication.

[0036] Figure 5 is a block diagram illustrating a first exemplary embodiment of a control plane protocol stack of a UE performing sidelink communication.

[0037] Figure 6 is a block diagram illustrating a second exemplary embodiment of a control plane protocol stack of a UE performing sidelink communication.

[0038] Figure 7 is a sequence diagram illustrating a first exemplary embodiment of a method for reporting SL CSI.

[0039] Figure 8 is a sequence diagram illustrating a second exemplary embodiment of a method for reporting SL CSI.

[0040] Figure 9 is a sequence diagram illustrating a third exemplary embodiment of a method for reporting SL CSI.

[0041] Figure 10 is a timing diagram showing a first exemplary embodiment of a transmission cycle of SL CSI.

[0042] Figure 11 is a sequence diagram illustrating a fourth exemplary embodiment of a method for reporting SL CSI.

[0043] Figure 12 is a sequence diagram illustrating a fifth exemplary embodiment of a method for reporting SL CSI. DETAILED DESCRIPTION

[0044] Although the present invention is susceptible to various modifications and alternative forms, specific embodiments are shown in the drawings by way of example and described in detail. However, it should be understood that this description is not intended to limit the invention to the specific embodiments, but on the contrary, the invention is intended to cover all modifications, equivalents and alternative forms that fall within the spirit and scope of the invention.

[0045] Although the terms "first," "second," etc. may be used herein with respect to various elements, these elements should not be construed as being limited by these terms. These terms are used solely to distinguish one element from another. For example, a first element may be referred to as a second element, and a second element may be referred to as a first element, without departing from the scope of the present invention. The term "and / or" includes any and all combinations of one or more of the associated listed items.

[0046] It will be understood that when an element is referred to as being “connected” or “coupled” to another element, the element can be directly connected or coupled to the other element, or intervening elements may be present. In contrast, when an element is referred to as being “directly connected” or “directly coupled” to another element, there are no intervening elements.

[0047] The terms used herein are for the purpose of describing specific embodiments only and are not intended to limit embodiments of the present invention. As used herein, the singular is intended to include the plural, unless the context clearly indicates otherwise. It will be further understood that, when used herein, the terms "comprise," "include," "include," and / or "comprising" specify the presence of the features, integers, steps, operations, elements, parts, and / or combinations thereof, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, parts, and / or combinations thereof.

[0048] Unless otherwise defined, all terms used herein, including technical and scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which the present invention belongs. It will be further understood that terms defined in commonly used dictionaries should be interpreted as having a meaning consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless explicitly defined as such herein.

[0049] Hereinafter, preferred exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. In describing the present invention, in order to facilitate overall understanding, the same reference numerals refer to the same elements throughout the description of the drawings, and their repeated description will be omitted.

[0050] Figure 1 It is a conceptual diagram showing a V2X communication scenario. Figure 1 As shown, V2X communication may include vehicle-to-vehicle (V2V) communication, vehicle-to-infrastructure (V2I) communication, vehicle-to-pedestrian (V2P) communication, vehicle-to-network (V2N) communication, etc. V2X communication may be supported by a cellular communication system (e.g., cellular communication system 140), and V2X communication supported by the cellular communication system 140 may be referred to as "cellular-V2X (C-V2X) communication." Here, the cellular communication system 140 may include a 4G communication system (e.g., an LTE communication system or an LTE-A communication system), a 5G communication system (e.g., an NR communication system), etc.

[0051] V2V communication may include communication between a first vehicle 100 (e.g., a communication node located in the vehicle 100) and a second vehicle 110 (e.g., a communication node located in the vehicle 110). Various driving information such as speed, heading, time, location, etc. may be exchanged between the vehicle 100 and the vehicle 110 through V2V communication. For example, autonomous driving (e.g., platooning) may be supported based on the driving information exchanged through V2V communication. The V2V communication supported in the cellular communication system 140 may be performed based on a "sidelink" communication technology (e.g., ProSe and D2D communication technology, etc.). In particular, the communication between the vehicle 100 and the vehicle 110 may be performed using at least one sidelink channel established between the vehicle 100 and the vehicle 110.

[0052] V2I communication can include communication between vehicle #1 100 and roadside infrastructure (e.g., roadside unit (RSU)) 120. Infrastructure 120 can also include traffic lights or streetlights located on the roadside. For example, when performing V2I communication, communication can be performed between a communication node located in vehicle #1 100 and a communication node located in a traffic light. Traffic information, driving information, etc. can be exchanged between vehicle #1 100 and infrastructure 120 through V2I communication. V2I communication supported in cellular communication system 140 can also be performed based on sidelink communication technology (e.g., ProSe communication technology and D2D communication technology, etc.). In particular, communication between vehicle #1 100 and infrastructure 120 can be performed using a sidelink channel.

[0053] V2P communication may include communication between vehicle #1 100 (e.g., a communication node located in vehicle #1 100) and person 130 (e.g., a communication node carried by person 130). Driving information of vehicle #1 100, such as speed, heading, time, and location, and movement information of person 130 may be exchanged between vehicle #1 100 and person 130 via V2P communication. The communication node located in vehicle #1 100 or the communication node carried by person 130 may be configured to generate an alert indicating danger by determining a dangerous situation based on the obtained driving information and movement information. V2P communication supported in cellular communication system 140 may be performed based on sidelink communication technology (e.g., ProSe communication technology and D2D communication technology, etc.). In particular, communication between the communication node located in vehicle #1 100 or the communication node carried by person 130 may be performed using at least one sidelink channel.

[0054] V2N communication may be communication between vehicle #1 100 (e.g., a communication node located in vehicle #1 100) and a server connected via a cellular communication system 140 (e.g., a cellular communication network). V2N communication may be performed based on 4G communication technology (e.g., LTE or LTE-A specified by the 3GPP standard) or 5G communication technology (e.g., NR specified by the 3GPP standard). In addition, V2N communication may be performed based on Wireless Access in Vehicular Environments (WAVE) communication technology or Wireless Local Area Network (WLAN) communication technology defined in Institute of Electrical and Electronics Engineers (IEEE) 802.11, or based on Wireless Personal Area Network (WPAN) communication technology defined in IEEE 802.15.

[0055] On the other hand, the cellular communication system 140 supporting V2X communication may be configured as follows.

[0056] Figure 2 is a conceptual diagram illustrating an exemplary embodiment of a cellular communication system.

[0057] like Figure 2 As shown, the cellular communication system may include an access network, a core network, etc. The access network may include a base station 210, a relay 220, user equipments (UEs) 231 to 236, etc. UEs 231 to 236 may include Figure 1 The communication nodes in the vehicle 100 and the vehicle 110 are located Figure 1 The communication nodes in the infrastructure 120, Figure 1 When the cellular communication system supports 4G communication technology, the core network may include a serving gateway (S-GW) 250, a packet data network (PDN) gateway (P-GW) 260, a mobility management entity (MME) 270, and the like.

[0058] When the cellular communication system supports 5G communication technology, the core network may include a user plane function (UPF) 250, a session management function (SMF) 260, an access and mobility management function (AMF) 270, etc. Alternatively, when the cellular communication system operates in non-standalone (NSA) mode, the core network composed of the S-GW 250, the P-GW 260, and the MME 270 can support both 4G communication technology and 5G communication technology, and the core network composed of the UPF 250, the SMF 260, and the AMF 270 can support both 5G communication technology and 4G communication technology.

[0059] In addition, when the cellular communication system supports network slicing technology, the core network can be divided into multiple logical network slices. For example, network slices supporting V2X communication (e.g., V2V network slices, V2I network slices, V2P network slices, V2N network slices, etc.) can be configured, and V2X communication can be supported by the V2X network slices configured in the core network.

[0060] The communication nodes (e.g., base stations, repeaters, UEs, S-GWs, P-GWs, MMEs, UPFs, SMFs, AMFs, etc.) constituting a cellular communication system may be configured to perform communication using at least one of the following communication technologies: Code Division Multiple Access (CDMA) technology, Time Division Multiple Access (TDMA) technology, Frequency Division Multiple Access (FDMA) technology, Orthogonal Frequency Division Multiplexing (OFDM) technology, Filtered OFDM technology, Orthogonal Frequency Division Multiple Access (OFDMA) technology, Single Carrier FDMA (SC-FDMA) technology, Non-Orthogonal Multiple Access (NOMA) technology, Generalized Frequency Division Multiplexing (GFDM) technology, Filter Bank Multi-Carrier (FBMC) technology, Universal Filtered Multi-Carrier (Universal Filtered Multi-Carrier) technology. Multi-Carrier, UFMC) technology and Space Division Multiple Access (SDMA) technology.

[0061] The communication nodes (e.g., base stations, relays, UEs, S-GWs, P-GWs, MMEs, UPFs, SMFs, AMFs, etc.) constituting a cellular communication system may be configured as follows.

[0062] Figure 3 is a conceptual diagram illustrating an exemplary embodiment of a communication node constituting a cellular communication system.

[0063] like Figure 3 As shown, the communication node 300 may include at least one processor 310, a memory 320, and a transceiver 330 connected to a network for performing communication. In addition, the communication node 300 may further include an input interface device 340, an output interface device 350, a storage device 360, etc. Each component included in the communication node 300 may be configured to communicate with each other when connected through a bus 370.

[0064] However, each component included in the communication node 300 may be connected to the processor 310 through a separate interface or a separate bus instead of the common bus 370. For example, the processor 310 may be connected to at least one of the memory 320, the transceiver 330, the input interface device 340, the output interface device 350, and the storage device 360 ​​through a dedicated interface.

[0065] The processor 310 may be configured to execute at least one instruction stored in at least one of the memory 320 and the storage device 360. The processor 310 may refer to a central processing unit (CPU), a graphics processing unit (GPU), or a dedicated processor that executes the method according to an embodiment of the present disclosure. Each of the memory 320 and the storage device 360 ​​may include at least one of a volatile storage medium and a non-volatile storage medium. For example, the memory 320 may include at least one of a read-only memory (ROM) and a random access memory (RAM).

[0066] Refer again Figure 2 In the communication system, base station 210 may form a macro cell or a small cell and may be connected to a core network via an ideal backhaul or a non-ideal backhaul. Base station 210 may be configured to transmit signals received from the core network to UEs 231 to 236 and relay 220, and may be configured to transmit signals received from UEs 231 to 236 and relay 220 to the core network. UE#1 231, UE#2 232, UE#4 234, UE#5 235, and UE#6 236 may belong to the cell coverage of base station 210. UE#1 231, UE#2 232, UE#4 234, UE#5 235, and UE#6 236 may connect to base station 210 by performing a connection establishment procedure with the base station. UE#1 231 , UE#2 232 , UE#4 234 , UE#5 235 , and UE#6 236 may communicate with the base station 210 after being connected to the base station 210 .

[0067] Relay 220 may be connected to base station 210 and may be configured to relay communications between base station 210 and UE#3 233 and UE#4 234. In other words, relay 220 may be configured to transmit signals received from base station 210 to UE#3 233 and UE#4 234, and to transmit signals received from UE#3 233 and UE#4 234 to base station 210. UE#4 234 may be within the cell coverage of both base station 210 and relay 220, while UE#3 233 may be within the cell coverage of relay 220. In other words, UE#3 233 may be outside the cell coverage of base station 210. UE#3 233 and UE#4 234 may connect to relay 220 by performing a connection establishment procedure with relay 220. UE#3 233 and UE#4 234 may be configured to communicate with the relay 220 after being connected to the relay 220 .

[0068] The base station 210 and the relay 220 may support multiple-input multiple-output (MIMO) technology (e.g., single-user (SU)-MIMO, multi-user (MU)-MIMO, massive MIMO, etc.), coordinated multipoint (CoMP) communication technology, carrier aggregation (CA) communication technology, unlicensed band communication technology (e.g., licensed assisted access (LAA), enhanced LAA (eLAA), etc.), sidelink communication technology (e.g., ProSe communication technology, D2D communication technology), etc. UE#1 231, UE#2 232, UE#5 235, and UE#6 236 may be configured to perform operations corresponding to the base station 210 and operations supported by the base station 210. UE#3 233 and UE#4 234 may be configured to perform operations corresponding to the relay 220 and operations supported by the relay 220.

[0069] In particular, the base station 210 may be referred to as a Node B (NB), an evolved Node B (eNB), a base transceiver station (BTS), a radio remote head (RRH), a transmission reception point (TRP), a radio unit (RU), a roadside unit (RSU), a radio transceiver, an access point, an access node, etc. The relay 220 may be referred to as a small base station, a relay node, etc. Each of UE#1 231 to UE#6 236 may be referred to as a terminal, an access terminal, a mobile terminal, a station, a subscriber station, a mobile station, a portable subscriber station, a node, a device, an on-broad unit (OBU), etc.

[0070] On the other hand, the communication between UE#5 235 and UE#6 236 can be performed based on a sidelink communication technology (e.g., ProSe communication technology, D2D communication technology). The sidelink communication can be performed based on a one-to-one scheme or a one-to-many scheme. When the sidelink communication technology is used to perform V2V communication, UE#5 235 can be located at Figure 1 The communication node in vehicle #1 100, UE #6 236 may be located at Figure 1 When performing V2I communication using the sidelink communication technology, UE#5 235 may be a communication node located in vehicle #2 110. Figure 1 The communication node in vehicle #1 100, UE #6 236 may be located at Figure 1 When performing V2P communication using the sidelink communication technology, UE#5 235 may be a communication node located in the infrastructure 120. Figure 1 The communication node in vehicle #1100, UE #6 236 can be Figure 1 The personnel 130 carry the communication nodes.

[0071] According to the locations of the UEs participating in the side link communication (e.g., UE#5 235 and UE#6 236), the scenarios in which the side link communication is applied can be classified as shown in Table 1 below. For example, Figure 2 The scenario of sidelink communication between UE#5 235 and UE#6 236 shown in FIG may be sidelink communication scenario #C.

[0072] [Table 1]

[0073]

[0074]

[0075] On the other hand, the user plane protocol stack of the UEs (eg, UE#5 235 and UE#6 236) performing sidelink communication may be configured as follows.

[0076] Figure 4 is a block diagram illustrating an exemplary embodiment of a user plane protocol stack of a UE performing sidelink communication.

[0077] like Figure 4 As shown, UE#5 235 can be Figure 2 UE#5 235 and UE#6 236 shown in FIG can be Figure 2 UE#6 236 is shown in FIG. The sidelink communication scenario between UE#5 235 and UE#6 236 may be one of the sidelink communication scenarios #A to #D in Table 1. The user plane protocol stack of each of UE#5 235 and UE#6 236 may include a physical (Physical, PHY) layer, a medium access control (MAC) layer, a radio link control (RLC) layer, and a packet data convergence protocol (PDCP) layer.

[0078] Sidelink communication between UE#5 235 and UE#6 236 can be performed using a PC5 interface (e.g., a PC5-U interface). Layer 2 identifiers (IDs) (e.g., source Layer 2 ID, destination Layer 2 ID) can be used for sidelink communication, and the Layer 2 IDs can be IDs configured for V2X communication (e.g., V2X services). In addition, in sidelink communication, hybrid automatic repeat request (HARQ) feedback operations can be supported, and RLC Acknowledged Mode (RLC AM) or RLC Unacknowledged Mode (RLC UM) can be supported.

[0079] On the other hand, the control plane protocol stack of the UEs (eg, UE#5 235 and UE#6 236) performing sidelink communication may be configured as follows.

[0080] Figure 5 is a block diagram illustrating a first exemplary embodiment of a control plane protocol stack of a UE performing sidelink communication, Figure 6 is a block diagram illustrating a second exemplary embodiment of a control plane protocol stack of a UE performing sidelink communication.

[0081] like Figure 5 and Figure 6 As shown, UE#5 235 can be Figure 2UE#5 235 shown in FIG, UE#6 can be Figure 2 The scenario of the sidelink communication between UE#5 235 and UE#6 236 can be one of the sidelink communication scenarios #A to #D of Table 1. Figure 5 The control plane protocol stack shown in may be a control plane protocol stack for transmitting and receiving broadcast information (eg, a Physical Sidelink Broadcast Channel (PSBCH)).

[0082] Figure 5 The control plane protocol stack shown in FIG may include a PHY layer, a MAC layer, an RLC layer, and a Radio Resource Control (RRC) layer. Sidelink communication between UE#5 235 and UE#6 236 may be performed using a PC5 interface (eg, a PC5-C interface). Figure 6 The control plane protocol stack shown in can be a control plane protocol stack for one-to-one side link communication. Figure 6 The control plane protocol stack shown in FIG may include a PHY layer, a MAC layer, an RLC layer, a PDCP layer, and a PC5 signaling protocol layer.

[0083] On the other hand, channels used in sidelink communication between UE#5 235 and UE#6 236 may include a physical sidelink shared channel (PSSCH), a physical sidelink control channel (PSCCH), a physical sidelink discovery channel (PSDCH), and a physical sidelink broadcast channel (PSBCH). The PSSCH may be used to transmit and receive sidelink data and may be configured in the UE (e.g., UE#5 235 or UE#6 236) through higher layer signaling. The PSCCH may be used to transmit and receive sidelink control information (SCI) and may also be configured in the UE (e.g., UE#5 235 or UE#6 236) through higher layer signaling.

[0084] The PSDCH may be used for a discovery process. For example, a discovery signal may be sent via the PSDCH. The PSBCH may be used to send and receive broadcast information (e.g., system information). In addition, a demodulation reference signal (DM-RS), a synchronization signal, and the like may be used in sidelink communications between UE#5 235 and UE#6 236. The synchronization signal may include a primary sidelink synchronization signal (PSSS) and a secondary sidelink synchronization signal (SSSS).

[0085] On the other hand, the sidelink transmission modes (TM) may be classified into sidelink TM#1 to TM#4 as shown in Table 2 below.

[0086] [Table 2]

[0087] SidelinkTM describe #1 Send using resources scheduled by the base station #2 UE sends data autonomously without the need for base station scheduling #3 In V2X communication, base station resources are used for transmission. #4 In V2X communication, UE sends data autonomously without the need for base station scheduling.

[0088] When supporting sidelink TM#3 or TM#4, each of UE#5 235 and UE#6 236 may be configured to perform sidelink communication using a resource pool configured by base station 210. A resource pool may be configured for each of sidelink control information and sidelink data.

[0089] The resource pool for sidelink control information can be configured based on an RRC signaling process (e.g., a dedicated RRC signaling process, a broadcast RRC signaling process). The resource pool for receiving sidelink control information can be configured through a broadcast RRC signaling process. When sidelink TM#3 is supported, the resource pool for sending sidelink control information can be configured through a dedicated RRC signaling process. In particular, the sidelink control information can be sent through resources scheduled by the base station 210 within the resource pool configured by the dedicated RRC signaling process. When sidelink TM#4 is supported, the resource pool for sending sidelink control information can be configured through a dedicated RRC signaling process or a broadcast RRC signaling process. In particular, the sidelink control information can be sent through resources autonomously selected by the UE (e.g., UE#5 235 or UE#6 236) within the resource pool configured by the dedicated RRC signaling process or the broadcast RRC signaling process.

[0090] When sidelink TM#3 is supported, a resource pool for transmitting and receiving sidelink data may not be configured. In particular, sidelink data may be transmitted and received using resources scheduled by base station 210. When sidelink TM#4 is supported, a resource pool for transmitting and receiving sidelink data may be configured using a dedicated RRC signaling procedure or a broadcast RRC signaling procedure. In particular, sidelink data may be transmitted and received using resources autonomously selected by a UE (e.g., UE#5 235 or UE#6 236) from a resource pool configured using a dedicated RRC signaling procedure or a broadcast RRC signaling procedure.

[0091] Hereinafter, a method for retransmitting sidelink data will be described. In an exemplary embodiment, the HARQ response may be referred to as a "HARQ acknowledgement (HARQ-ACK)". The HARQ response may be an ACK or a negative ACK (NACK). Even when describing a method to be performed at a first communication node in a communication node (e.g., transmission or reception of a signal), the corresponding second communication node may also perform a method corresponding to the method performed at the first communication node (e.g., reception or transmission of a signal). In other words, when describing the operation of UE#1 (e.g., vehicle #1), the corresponding UE#2 (e.g., vehicle #2) may be configured to perform an operation corresponding to the operation of UE#1. Conversely, when describing the operation of UE#2, the corresponding UE#1 may be configured to perform an operation corresponding to the operation of UE#2. In the exemplary embodiments described below, the operation of the vehicle may be the operation of a communication node located in the vehicle.

[0092] In an exemplary embodiment, signaling may be one or a combination of more than one of high-layer signaling, MAC signaling, and physical (PHY) signaling. Messages used for high-layer signaling may be referred to as "high-layer messages" or "high-layer signaling messages." Messages used for MAC signaling may be referred to as "MAC messages" or "MAC signaling messages." Messages used for PHY signaling may be referred to as "PHY messages" or "PHY signaling messages." High-layer signaling may refer to the operation of sending and receiving system information (e.g., Master Information Block (MIB), System Information Block (SIB)) and / or RRC messages. MAC signaling may refer to the operation of sending and receiving MAC control elements (CE). PHY signaling may refer to the operation of sending and receiving control information (e.g., Downlink Control Information (DCI), Uplink Control Information (UCI), SCI).

[0093] Sidelink signals may be synchronization signals and reference signals used for sidelink communications. For example, synchronization signals may be synchronization signal / physical broadcast channel (SS / PBCH) blocks, sidelink synchronization signals (SLSS), primary sidelink synchronization signals (PSSS), secondary sidelink synchronization signals (SSSS), etc. Reference signals may be channel state information reference signals (CSI-RS), DM-RS, phase tracking reference signals (PT-RS), cell-specific reference signals (CRS), sounding reference signals (SRS), discovery reference signals (DRS), etc.

[0094] A sidelink channel may be a PSSCH, PSCCH, PSDCH, PSBCH, or a physical sidelink feedback channel (PSFCH). Furthermore, a sidelink channel may refer to a sidelink channel that includes a sidelink signal mapped to specific resources in the corresponding sidelink channel. Sidelink communications may support broadcast services, multicast services, groupcast services, and unicast services.

[0095] Sidelink communication can be performed based on a single SCI scheme or a multiple SCI scheme. When a single SCI scheme is used, data transmission (e.g., sidelink data transmission, sidelink shared channel (Sidelink-Shared Channel, SL-SCH) transmission) can be performed based on a single SCI (e.g., 1st-stage SCI). When a multiple SCI scheme is used, data transmission can be performed using two SCIs (e.g., 1st-stage SCI and 2nd-stage SCI). SCI can be sent through PSCCH and / or PSSCH. When a single SCI scheme is used, SCI (e.g., 1st-stage SCI) can be sent through PSCCH. When a multiple SCI scheme is used, 1st-stage SCI can be sent through PSCCH, and 2nd-stage SCI can be sent through PSCCH or PSSCH. 1st-stage SCI can be referred to as "1st-stage SCI" and 2nd-stage SCI can be referred to as "2nd-stage SCI".

[0096] The Phase 1 SCI may include one or more of the following information elements: priority information, frequency resource allocation information, time resource allocation information, resource reservation period information, DMRS pattern information, Phase 2 SCI format information, beta_offset indicator, number of DMRS ports, and modulation and coding scheme (MCS) information. The Phase 2 SCI may include one or more of the following information elements: HARQ process identifier (ID), redundancy version (RV), source ID, destination ID, CSI request information, area ID, and communication range requirement.

[0097] On the other hand, sidelink communication may require channel state information (CSI) between terminals. In other words, sidelink communication can be performed based on CSI. CSI may include one or more of the following: channel quality indicator (CQI), rank indicator (RI) and precoding matrix indicator (PMI). In addition, CSI may further include reference signal received power (RSRP), reference signal received quality (RSRQ) and / or received signal strength indicator (RSSI). In the following exemplary embodiments, a method for triggering SL CSI reporting, a method for triggering SL CSI measurement, a method for configuring SL CSI measurement, a method for configuring SL CSI reporting, etc. will be described. SL CSI may represent CSI for sidelink communication. In the following exemplary embodiments, CSI may represent SLCSI.

[0098] Figure 7 is a sequence diagram showing a first exemplary embodiment of a method for reporting SL CSI. Figure 7 , the communication system may include a first terminal and a second terminal. Side link communication may be performed between the first terminal and the second terminal. The first terminal may be Figure 2 The second terminal may be UE#5235 shown in Figure 2 UE#6 236 shown in FIG. Each of the first terminal and the second terminal can be connected to Figure 3 The communication node 300 shown in FIG. 1 is configured identically or similarly. Each of the first terminal and the second terminal may support Figures 4 to 6Each of the first terminal and the second terminal may support the sidelink TM defined in Table 2. The first terminal that transmits a reference signal (e.g., CSI-RS, DMRS) may be referred to as a transmitting (Tx) terminal, and the second terminal that receives the reference signal may be referred to as a receiving (Rx) terminal.

[0099] The first terminal may be configured to generate information indicating the triggering of an SL CSI report. The triggering of the SL CSI report may be indicated implicitly or explicitly. In an exemplary embodiment, the "information indicating the triggering of the SL CSI report" may be referred to as "trigger indication information". The trigger indication information may indicate whether the SL CSI report is triggered. The trigger indication information may be included in at least one of the stage 1 SCI and / or the stage 2 SCI. For example, the CSI request information included in the stage 2 SCI may be used as the trigger indication information. The first terminal may be configured to send trigger indication information (e.g., SCI including trigger indication information) to the second terminal (S701). The second terminal may be configured to receive the SCI from the first terminal and identify the trigger indication information included in the SCI. The second terminal may be configured to determine whether the SL CSI report is triggered based on the trigger indication information.

[0100] The first terminal may be configured to send a reference signal (e.g., SL CSI-RS) (S702). The SL CSI-RS may be a CSI-RS for sidelink communication. The reference signal may be sent using resources configured by a base station (e.g., a base station to which the first terminal is connected). When the SL CSI report is triggered, the second terminal may be configured to perform a measurement operation based on the reference signal received from the first terminal (S703). The second terminal may be configured to generate SLCSI based on the result of the measurement operation. SL CSI may include one or more of CQI, RI, and PMI. SL CSI may be instantaneous channel state information and / or cumulative channel state information (e.g., statistical channel state information, average channel state information). SL CSI may be broadband channel state information.

[0101] The second terminal may be configured to send SL CSI to the first terminal (S704). For example, the second terminal may be configured to perform a sensing operation on the side link resources, and when it is determined through the sensing operation that the side link resources are in an idle state, the second terminal may be configured to use the side link resources to send SLCSI. SL CSI may be sent on a side link channel (e.g., PSSCH, PSCCH, PSFCH). For example, a MAC control element (CE) including SL CSI may be sent on a side link channel. When a MAC CE including SL CSI is sent on the PSSCH, the SL CSI may be multiplexed with the side link data in the PSSCH. The first terminal may be configured to receive SL CSI from the second terminal and perform side link communication (e.g., side link communication based on a unicast scheme) based on the SL CSI.

[0102] The time for sending SL CSI (for example, the delay limit value of the SL SCI report) can be set based on at least one of system information, RRC signaling, MAC signaling and PHY signaling. The time for sending SL CSI can be referred to as "sl-LatencyBound-CSI-Report". The time for sending SL CSI can be set by the base station and / or the first terminal. For example, the first terminal (i.e., the transmitting terminal) can be configured to send an RRC message (for example, an RRC reconfiguration side link message) including information indicating the time for sending SL CSI (for example, sl-LatencyBound-CSI-Report) to the second terminal. The information indicating the time for sending SL CSI can be used for unicast-based side link communication between the first terminal and the second terminal. The time for sending SL CSI can be set to a fixed value in the communication system.

[0103] The time for sending SL CSI can be set specific to the resource pool, specific to the SL (e.g., specific to the link), or specific to the terminal (e.g., specific to the UE). The time for sending SL CSI can be set in time slots and can indicate a delay limit starting from the time when the trigger indication information is received (e.g., the time slot in which the second stage SCI is received). In other words, the time for sending SL CSI can be indicated by a time slot offset starting from the time when the second stage SCI including the trigger indication information (e.g., CSI request information) is received. Alternatively, the time for sending SL CSI can be indicated by a time slot offset starting from the time when the first stage SCI associated with the second stage SCI including the trigger indication information (e.g., CSI request information) is received. The time for sending SL CSI can be set to one of 3 to 160.

[0104] In an exemplary embodiment, the time when the trigger indication information is received (or the time when the trigger indication information is sent) may be referred to as "N", and the time when the SL CSI is sent (or the time when the SL CSI is received) may be referred to as "K". In other words, K may be the delay limit value for the SL CSI report. N may indicate a specific symbol, a specific mini-slot, a specific time slot, or a specific subframe within the time period for triggering the SL CSI report. K may be a time offset. Each of N and K may be set in units of symbols, mini-slots, time slots, or subframes. Each of N and K may be an integer greater than or equal to 0. The time unit of N may be the same as the time unit of K. Alternatively, the time unit of N may be different from the time unit of K.

[0105] When the time unit of N is the same as the time unit of K, the time for transmitting the SL CSI may be the (N+K)th time slot after K time slots starting from the Nth time slot. In particular, the SL CSI may be transmitted in the (N+K)th time slot. When the time unit is a subframe, the time for transmitting the SL CSI may be the (N+K)th subframe after K subframes starting from the Nth subframe. The time for transmitting the SL CSI may be set based on a time unit other than the above-mentioned time unit. Even when the exemplary embodiment is described based on a time slot, the exemplary embodiment may be applied to other time units (e.g., a symbol, a mini-slot, a subframe).

[0106] In a communication system, K (e.g., time offset, time slot offset) can be set to a fixed value, and the SLCSI report can be configured to be performed before the (N+K)th time slot. The base station can be configured to set K and send system information (e.g., MIB, SIB) including K. Alternatively, the first terminal (e.g., a transmitting terminal) can be configured to set K and send a message (e.g., an RRC message) including K. In particular, K can be fixed to a value. When no SL CSI is received in the (N+K)th time slot, the first terminal (e.g., a transmitting terminal) can be configured to determine that the trigger indication information has not yet been applied to the second terminal (e.g., a receiving terminal). Alternatively, the first terminal can be configured to determine that the second terminal has failed to reserve (e.g., ensure) resources for the SL CSI report. In particular, the first terminal can be configured to retransmit the trigger indication information to the second terminal to request an SLCSI report.

[0107] In addition, K (e.g., the time for sending SL CSI) can be set through RRC signaling and / or MAC signaling (e.g., MAC CE). In addition, K can be set specific to the resource pool, specific to the SL (e.g., specific to the link), or specific to the terminal. When K is set specific to the resource pool, K can be included in the configuration information of the resource pool, and the configuration information of the resource pool can be sent through RRC signaling and / or MAC signaling. In particular, the same K can be used within the corresponding resource pool. When K is set specific to the SL, K can be included in the configuration information of the side link, and the configuration information of the side link can be sent through RRC signaling and / or MAC signaling. In particular, the same K can be used in the corresponding side link. When K is set specific to the terminal, K can be included in the dedicated configuration information, and the dedicated configuration information can be sent through RRC signaling and / or MAC signaling. In this case, K can be set independently for each terminal.

[0108] In addition, K set by RRC signaling and / or MAC signaling can be semi-static information. Therefore, K can be variable. For example, K can be changed by a combination of "RRC signaling and / or MAC signaling" and PHY signaling (e.g., SCI). Alternatively, K can be changed using only PHY signaling. In other words, K can be changed dynamically.

[0109] Table 3

[0110] Information Bit K 00 4 01 6 10 8 11 12

[0111] The information bits of K defined in Table 3 may be set by higher layer signaling and / or system information. Two information bits may be used to indicate four K values. K may be sent together with the trigger indication information.

[0112] Figure 8 is a sequence diagram illustrating a second exemplary embodiment of a method for reporting SL CSI.

[0113] Reference Figure 8 , the communication system may include a first terminal and a second terminal. Side link communication may be performed between the first terminal and the second terminal. The first terminal may be Figure 2 The second terminal may be UE#5 235 shown in FIG. Figure 2 UE#6 236 shown in FIG. Each of the first terminal and the second terminal can be connected to Figure 3 The communication node 300 shown in FIG. 1 is configured identically or similarly. Each of the first terminal and the second terminal may support Figures 4 to 6Each of the first terminal and the second terminal may support the sidelink TM defined in Table 2. The first terminal that transmits a reference signal (e.g., CSI-RS, DMRS) may be referred to as a transmitting (Tx) terminal, and the second terminal that receives the reference signal may be referred to as a receiving (Rx) terminal.

[0114] The first terminal may be configured to send feedback indication information and K to the second terminal (S801). The feedback indication information and K may be included in an SCI (e.g., phase 1 SCI and / or phase 2 SCI). In another exemplary embodiment, K may be included in an RRC message sent from the first terminal, and the feedback indication information may be included in the SCI sent from the first terminal. Alternatively, the feedback indication information and K may be sent by a base station instead of the first terminal. For example, the base station may be configured to send an RRC message containing the feedback indication information and K. In particular, the feedback indication information may be "sl-CSI-Acquisition", and K may be "sl-LatencyBound-CSI-Report".

[0115] The second terminal may be configured to receive feedback indication information and K from the first terminal or the base station. The second terminal may be configured to determine triggering of SL CSI reporting based on the feedback indication information. K may start from the time the feedback indication information is received. Accordingly, the second terminal may be configured to start a timer corresponding to K from the time the feedback indication information is received.

[0116] The first terminal may be configured to transmit a reference signal (e.g., SL CSI-RS) (S802). The SL CSI-RS may be a CSI-RS for sidelink communication. The reference signal may be transmitted using resources configured by a base station (e.g., a base station to which the first terminal is connected). When the SL CSI report is triggered, the second terminal may be configured to perform a measurement operation based on the reference signal received from the first terminal (S803). The second terminal may be configured to generate an SLCSI based on the result of the measurement operation. The SL CSI may include one or more of CQI, RI, and PMI.

[0117] When the timer corresponding to K has not expired, the second terminal may be configured to send SL CSI to the first terminal (S804). In other words, the SL CSI may be sent within K from the time the trigger indication information is received. On the other hand, when the timer corresponding to K expires, the second terminal may not send SL CSI. In other words, from the time the trigger indication information is received, SL CSI may not be sent after K. SL CSI may be sent on a side link channel (e.g., PSSCH, PSCCH, PSFCH). The first terminal may be configured to receive SL CSI from the second terminal, and may perform side link communication (e.g., side link communication based on a unicast scheme) based on the SL CSI.

[0118] Figure 9 is a sequence diagram illustrating a third exemplary embodiment of a method for reporting SL CSI.

[0119] Reference Figure 9 , the communication system may include a first terminal and a second terminal. Side link communication may be performed between the first terminal and the second terminal. The first terminal may be Figure 2 The second terminal may be UE#5 235 shown in FIG. Figure 2 UE#6 236 shown in FIG. Each of the first terminal and the second terminal can be connected to Figure 3 The communication node 300 shown in FIG. 1 is configured identically or similarly. Each of the first terminal and the second terminal may support Figures 4 to 6 Each of the first terminal and the second terminal may support the sidelink TM defined in Table 2. The first terminal that transmits a reference signal (e.g., CSI-RS, DMRS) may be referred to as a transmitting (Tx) terminal, and the second terminal that receives the reference signal may be referred to as a receiving (Rx) terminal.

[0120] Step S901 can be Figure 8 Step S801 shown in FIG is performed identically or similarly, and step S902 can be performed identically or similarly to step S801 shown in FIG. Figure 8 The same or similar execution as step S802 shown in FIG, step S903 can be performed with Figure 8 Here, K may be set to 6. In particular, the SL CSI transmission period (eg, the SL CSI monitoring period) may be configured as follows.

[0121] Figure 10 is a timing diagram showing a first exemplary embodiment of a transmission cycle of SL CSI.

[0122] Reference Figure 10, the time slot in which the trigger indication information (for example, the trigger indication information and K) is received may be time slot #N, and K may be set to 6. In this case, the transmission period of SL CSI (for example, the monitoring period of SL CSI) may be from the end point of time slot #N to the end point of time slot #(N+6). The second terminal may be configured to send SL CSI to the first terminal in the transmission period of SL CSI. The first terminal may be configured to perform a monitoring operation within the monitoring period of SL CSI to receive SL CSI. When SL CSI is transmitted on PSCCH, the first terminal may be configured to perform a monitoring operation on PSCCH within the monitoring period of SL CSI. When SL CSI is transmitted on PSSCH, the first terminal may be configured to perform a monitoring operation on PSSCH within the monitoring period of SL CSI.

[0123] Reference Figure 9 and Figure 10 , the second terminal may not be able to send SLCSI to the first terminal within the SL CSI transmission period. When the SL CSI transmission period ends (for example, when the timer corresponding to K expires), the second terminal can be configured to stop the sensing operation of the side link resources used for SL CSI reporting. In other words, the second terminal can be configured to stop the transmission operation of SL CSI. When no SL CSI is received within the SL CSI monitoring period, the first terminal can be configured to stop the monitoring operation for obtaining SL CSI. The monitoring operation can be stopped after time slot #(N+6).

[0124] On the other hand, the PSCCH containing SL CSI can be identified by various schemes. For example, a cyclic redundancy check (CRC) mask value or a scrambling sequence (e.g., a scrambling identifier (ID), a sequence ID) for the PSCCH containing SL CSI can be configured. In particular, the second terminal can be configured to send the PSCCH containing SL CSI using a CRC mask value or a scrambling sequence. The CRC mask value of the PSCCH containing SL CSI can be the same as the CRC mask value of the PSCCH containing the trigger indication information for triggering the corresponding SL CSI report. The scrambling sequence of the PSCCH containing SL CSI can be the same as the scrambling sequence of the PSCCH including the trigger indication information for triggering the corresponding SL CSI report. The scrambling ID (e.g., a sequence ID) can be an ID set for the SL CSI report. The scrambling ID can be set specific to the resource pool, specific to the SL dedicated, or specific to the terminal.

[0125] exist Figure 10In the exemplary embodiment shown, the second terminal may be configured to stop sensing sidelink resources used for SL CSI reporting starting from time slot #(N+7). That is, the operation for reporting SL CSI may be stopped. Even after time slot #(N+6), when sidelink resources are available (e.g., reserved), the operation for reporting SL CSI may be stopped.

[0126] When SL CSI is not received from the second terminal, the first terminal may be configured to retransmit the trigger indication information as needed. When K is indicated by PHY signaling (e.g., SCI), the first terminal may be configured to reset K and send SCI containing the reset K. The reset K may be a value greater than or less than the previous K. The second terminal may be configured to identify the reset K by receiving the SCI and start a timer corresponding to the reset K.

[0127] When the first terminal that has not received the SL CSI retransmits the trigger indication information, it may also send information indicating the retransmission of the trigger indication information (hereinafter referred to as the "retransmission indicator"). The retransmission indicator may indicate whether the trigger indication information is the initial trigger indication information or the retransmitted trigger indication information. In particular, the value of the SL CSI reported to the first terminal may vary based on whether the trigger indication information is retransmitted. When the retransmission indicator indicates the retransmitted trigger indication information, the second terminal may be configured to send the previous SL CSI (for example, the SL CSI that failed to be sent) to the first terminal. When the trigger indication information indicates the initial trigger indication information, the second terminal may be configured to send the current SL CSI to the first terminal.

[0128] On the other hand, the time (eg, K) for sending the SL CSI may be reset. The method of resetting the time for sending the SL CSI may be as follows.

[0129] Figure 11 is a sequence diagram illustrating a fourth exemplary embodiment of a method for reporting SL CSI.

[0130] Reference Figure 11 , the communication system may include a first terminal and a second terminal. Side link communication may be performed between the first terminal and the second terminal. The first terminal may be Figure 2 The second terminal may be UE#5 235 shown in FIG. Figure 2 UE#6 236 shown in FIG. Each of the first terminal and the second terminal can be connected to Figure 3 The communication node 300 shown in FIG. 1 is configured identically or similarly. Each of the first terminal and the second terminal may support Figures 4 to 6Each of the first terminal and the second terminal may support the sidelink TM defined in Table 2. The first terminal that transmits a reference signal (e.g., CSI-RS, DMRS) may be referred to as a transmitting (Tx) terminal, and the second terminal that receives the reference signal may be referred to as a receiving (Rx) terminal.

[0131] Step S1101 can be Figure 9 Step S901 is performed the same or similarly as shown, and step S1102 can be performed the same or similarly as shown. Figure 9 Step S902 is performed the same or similarly as shown, and step S1103 can be performed the same or similarly as shown. Figure 9 Step S903 shown in FIG. 1 is performed identically or similarly to step S903. In step S1101, an SCI including trigger indication information may be received in time slot #N. K may be set to 6. K may be set via RRC signaling (e.g., PC5 RRC signaling). The second terminal may not be able to send SL CSI to the first terminal before time slot #(N+6) or in time slot #(N+6), and the first terminal may not be able to receive SL CSI from the second terminal before time slot #(N+6) or in time slot #(N+6).

[0132] In particular, the first terminal may reset K. For example, the first terminal may set K to 12. The first terminal may be configured to send trigger indication information and reset K (for example, 12) to the second terminal (S1104). The reset K may be sent via a MAC message and / or a PHY message. The information indicating the reset K sent in step S1104 may be configured based on Table 3. For example, the information indicating the reset K may be "11". In addition, a retransmission indicator may be sent to the second terminal in step S1104. The retransmission indicator may indicate that the trigger indication information is retransmitted trigger indication information. The second terminal may be configured to receive the trigger indication information, the reset K, and the retransmission indicator from the first terminal. The second terminal may be configured to determine that the trigger indication information is retransmitted trigger indication information based on the retransmission indicator, and perform a measurement operation on the reference signal according to the trigger indication information. In addition, the second terminal may be configured to start a timer corresponding to the reset K from the time the trigger indication information is received, and send the SL CSI to the first terminal as the result of the measurement operation before the timer expires.

[0133] In addition, for each retransmission of the trigger indication information, K can increase or decrease at a preconfigured rate. For example, if the initial K is 6, K can increase by 2 each time the trigger indication information is retransmitted. Alternatively, K can be increased by 1 times for each retransmission of the trigger indication information. In addition, a maximum value of K can be set, and K can be set to not exceed the maximum value. Each of the increase, decrease, increase rate, decrease rate and maximum value of K can be set through at least one of system information, RRC message (e.g., PC5 RRC message), MAC message and PHY message. Each of the increase, decrease, increase rate, decrease rate and maximum value of K can be set specific to the resource pool, specific to the side link or specific to the terminal. The maximum number of retransmissions of the trigger indication information can be set, and the maximum number of retransmissions can be set through at least one of system information, RRC message (e.g., PC5 RRC message), MAC message and PHY message.

[0134] Based on the type of SL CSI, the method of setting K and / or the method of resetting K (e.g., the method of changing K) may vary. Referring to Tables 4 and 5 below, the amount of increase or decrease in K may vary depending on the type of SL CSI (e.g., instantaneous channel state information, average channel state information, filtered channel state information).

[0135] Table 4

[0136]

[0137] Table 5

[0138]

[0139]

[0140] The averaged / filtered channel state information may be channel state information for a longer period of time than the instantaneous channel state information. In Table 4, K for the averaged / filtered channel state information may be set equal to or greater than K for the instantaneous channel state information. For each retransmission of the trigger indication information, K for the averaged / filtered channel state information may be increased by 1 times. For each retransmission of the trigger indication information, K for the instantaneous channel state information may be reduced by half.

[0141] In Table 5, for each retransmission of the trigger indication information, K for the averaged / filtered channel state information may be increased by 2, and K for the instantaneous channel state information may remain unchanged even when the trigger indication information is retransmitted. The SL CSI type may be set via at least one of system information, RRC messages, MAC messages, and PHY messages. For example, the SL CSI type may be set by the base station or the first terminal. Each of the first terminal and the second terminal may reset K based on a reset method according to the SL CSI type.

[0142] Table 4 or Table 5 may be configured by higher-layer signaling, and each of the first terminal and the second terminal may be configured to determine K according to the type of SL CSI and the number of retransmissions of the trigger indication information based on Table 4 or Table 5. In another exemplary embodiment, an increase / decrease amount or an increase / decrease rate according to the type of SL CSI may be set by higher-layer signaling, and each of the first terminal and the second terminal may be configured to determine K based on the type of SL CSI and the number of retransmissions of the trigger indication information.

[0143] The type of SL CSI may not be limited to instantaneous channel state information, average channel state information, and filtered channel state information. For example, the type of SL CSI may vary according to CQI, RI, and / or PMI. The first type of SL CSI may include CQI and RI, and the second type of SL CSI may include PMI.

[0144] In addition, K can be sent together with the trigger indication information. In other words, K can be sent each time in the step of sending the trigger indication information. In particular, the second terminal can be configured to update the timer according to the received K. When K is reset according to a preconfigured increase / decrease amount or increase / decrease rate, it may happen that the second terminal sends SL CSI to the first terminal but the first terminal does not receive the SL CSI. This problem may occur when the K identified by the first terminal is different from the K identified by the second terminal. To avoid this problem, when K is reset according to a preconfigured increase / decrease amount or increase / decrease rate for each sending of the trigger indication information, information indicating whether the corresponding trigger indication information is a retransmitted trigger indication information (for example, a retransmission indicator) can be explicitly or implicitly indicated by the SCI.

[0145] If the second terminal sends SL CSI to the first terminal, but the first terminal does not receive the SL CSI, the first terminal may be configured to send trigger indication information to the second terminal in order to retransmit the SL CSI. The second terminal that sends the SL CSI may be configured to identify the trigger indication information received from the first terminal as new trigger indication information (for example, initial trigger indication information). In particular, the K applied to the first terminal may be different from the K applied to the second terminal. When the first terminal notifies the second terminal of K together with the trigger indication information, the second terminal may be configured to identify whether the current trigger indication information is the initial trigger indication information or the retransmitted trigger indication information based on K. In addition, the second terminal may be configured to determine the number of times the current trigger indication information has been retransmitted based on K. The above scheme can be understood as a scheme in which a retransmission indicator is sent together with the trigger indication information.

[0146] A toggle bit may be used instead of K to indicate whether the trigger indication information is initial trigger indication information or retransmitted trigger indication information. To indicate whether the trigger indication information is initial trigger indication information or retransmitted trigger indication information, a specific field (e.g., a field included in the SCI) may be reused or a new field may be used.

[0147] When there are multiple SL CSIs in the second terminal, the information indicating whether the trigger indication information included in the SCI is retransmitted can be used to indicate one or more SL CSIs in the multiple SL CSIs. The multiple SL CSIs can be divided based on the time when each SL CSI is measured.

[0148] Table 6

[0149]

[0150]

[0151] Referring to Table 6, the trigger indication information included in the SCI (e.g., the first stage SCI or the second stage SCI) can be configured as 2 bits. The trigger indication information set to "01" can indicate the initial trigger indication information. The second terminal can be configured to identify the number of retransmissions of the trigger indication information based on the trigger indication information included in the SCI. Alternatively, the fields included in the SCI can be reused to indicate the content defined in Table 6. The fields included in the SCI can implicitly indicate the content defined in Table 6.

[0152] When K increases significantly, the probability of SL CSI reporting failure due to failure in sensing the side link resource in the second terminal (e.g., the receiving terminal) is reduced. When K has a smaller value, the monitoring period of SL CSI in the first terminal (e.g., the transmitting terminal) (e.g., the monitoring period of the PSCCH or PSSCH including the SL CSI) can be reduced, and the SL CSI reporting process can be completed quickly.

[0153] The first terminal may be configured to identify the status of the sidelink resources capable of transmitting SL CSI based on the channel busy ratio (CBR) of the sidelink, and may be configured to increase or decrease K based on the identification result. In response to determining that the number of terminals using and / or wishing to use resources belonging to the resource pool is small based on the CBR, the first terminal may be configured to determine that increasing K is meaningless. In particular, the first terminal may be configured to maintain or decrease K and send the same K (or decreased K) together with the trigger indication information.

[0154] In response to determining, based on the CBR, that a large number of terminals are using and / or wishing to use resources belonging to the resource pool, the first terminal may increase K. In other words, the first terminal may be configured to transmit the increased K together with the trigger indication information. In particular, the probability of SL CSI reporting failure due to sidelink resource sensing failure may be reduced. In the above operation, in addition to the CBR, a combination of parameters related to the channel state (e.g., channel condition) may also be used.

[0155] In the step of retransmitting the trigger indication information based on a specific threshold of the parameter used, an increased K or decreased K may be transmitted. To reset K, a condition related to the threshold of the parameter used by the first terminal may be configured. For example, the amount of increase or decrease of K may be set for each of the cases where the parameter is greater than or equal to the threshold and the case where the parameter is less than the threshold. Alternatively, the rate of increase or decrease of K may be set for each of the cases where the parameter is greater than or equal to the threshold and the case where the parameter is less than the threshold.

[0156] When one or more parameters are used, the amount of increase / decrease and / or the rate of increase / decrease of K may be determined based on a threshold for each of the one or more parameters. Specifically, the threshold may be set via one or more of system information, RRC signaling, MAC signaling, and PHY signaling. The threshold may be resource pool-specific, sidelink-specific, or terminal-specific.

[0157] On the other hand, Figure 8 、 Figure 9 and Figure 11In the exemplary embodiment shown, the time offset (e.g., time slot offset) may start from the time the trigger indication information is received (or the time the trigger indication information is sent). Alternatively, the time offset may start from the side link resource configured for data transmission.

[0158] Figure 12 is a sequence diagram illustrating a fifth exemplary embodiment of a method for reporting SL CSI.

[0159] Reference Figure 12 , the communication system may include a first terminal and a second terminal. Side link communication may be performed between the first terminal and the second terminal. The first terminal may be Figure 2 The second terminal may be UE#5 235 shown in FIG. Figure 2 UE#6 236 shown in FIG. Each of the first terminal and the second terminal can be connected to Figure 3 The communication node 300 shown in FIG. 1 is configured identically or similarly. Each of the first terminal and the second terminal may support Figures 4 to 6 Each of the first terminal and the second terminal may support the sidelink TM defined in Table 2. The first terminal that transmits a reference signal (e.g., CSI-RS, DMRS) may be referred to as a transmitting (Tx) terminal, and the second terminal that receives the reference signal may be referred to as a receiving (Rx) terminal.

[0160] The first terminal may be configured to send an SCI (e.g., stage 2 SCI) including trigger indication information (e.g., CSI request information) to the second terminal (S1201). In step S1201, K (e.g., information about the time of sending SL CSI) may be sent together with the trigger indication information. In addition, K may be sent via an RRC message (e.g., a PC5 RRC message), and the trigger indication information may be sent via the SCI. Alternatively, K may be set by the base station. The second terminal may be configured to receive the trigger indication information and / or K from the first terminal. Alternatively, the second terminal may be configured to receive K from the base station.

[0161] The first terminal may be configured to send a reference signal (S1202). The reference signal may be sent via a side link resource configured by the base station. When the SL CSI report is triggered, the second terminal may be configured to perform a measurement operation based on the reference signal received from the first terminal (S1203). The second terminal may be configured to generate SL CSI as a result of the measurement operation. When the trigger indication information is received in time slot #N, the second terminal may be configured to send SL CSI to the first terminal in time slot #(N+LK) (S1204). SL CSI may be sent on PSCCH, PSSCH and / or PSFCH. In particular, L may represent a time period from the time the trigger indication information is received to the side link resource scheduled by the SCI associated with the trigger indication information (or the SCI not associated with the corresponding trigger indication information). L may be set in units of symbols, mini-slots, time slots or subframes. In addition, L may be an integer greater than or equal to 0.

[0162] The first terminal may be configured to perform a monitoring operation to receive SL CSI in a time period from slot #N to slot #(N+LK). When SL CSI is received in slot #(N+LK), the first terminal may be configured to determine the received SL CSI as valid SL CSI. On the other hand, when SL CSI is received after slot #(N+LK), the first terminal may be configured to determine the received SL CSI as invalid SL CSI. In this case, the first terminal may discard the SLCSI.

[0163] The first terminal may be configured to send SL data to the second terminal in the side link resource scheduled by the SCI (S1205). The second terminal may be configured to receive SL data from the first terminal by performing a monitoring operation on the side link resource scheduled by the SCI. The above operation may also be applied when SL data of a terminal different from the second terminal receiving the trigger indication information exists in the first terminal.

[0164] In another exemplary embodiment, K may start from the sidelink resources scheduled by the SCI. Specifically, the second terminal may be configured to transmit the SL CSI to the first terminal in time slot #(N+L+K). The first terminal may be configured to perform a monitoring operation to obtain the SL CSI during a time interval from time slot #N to time slot #(N+L+K).

[0165] The time for sending SL CSI (e.g., a delay limit for SL CSI reporting) may be set based on the processing time for SL CSI and / or the processing time for SL data transmission in the first terminal. The time for sending SL CSI may be a fixed value in the communication system. The time for sending SL CSI may be set via one or more of system information, RRC signaling, MAC signaling, and PHY signaling. The time for sending SL CSI may be set for a specific resource pool, a specific sidelink, or a specific terminal. Figure 8 、 Figure 9 and / or Figure 11 The exemplary embodiments shown in FIG. 4 can be applied to Figure 12 An exemplary embodiment is shown in .

[0166] The exemplary embodiments of the present disclosure may be implemented as program instructions that can be executed by various computers and recorded on a computer-readable medium. The computer-readable medium may include program instructions, data files, data structures, or a combination thereof. The program instructions recorded on the computer-readable medium may be specifically designed and configured for the present disclosure, or may be well-known and available to those skilled in the art of computer software.

[0167] Examples of computer-readable media may include hardware devices such as ROM, RAM, and flash memory, which are specifically configured to store and execute program instructions. Examples of program instructions include, for example, machine code generated by a compiler, and high-level language code that can be executed by a computer using an interpreter. The above-mentioned exemplary hardware devices may be configured to operate as at least one software module to execute the embodiments of the present disclosure, and vice versa.

[0168] Although the embodiments of the present disclosure and its advantages have been described in detail, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the disclosure as described in the claims.

Claims

1. A method for operating a first terminal in a communication system, the method comprising the following steps: Sending information indicating a delay limit value of a time slot number of a side link (SL) channel state information (CSI) report to the second terminal; Sending sidelink control information (SCI) to the second terminal, the SCI including information for triggering CSI reporting, wherein the information for triggering CSI reporting causes a timer associated with the delay limit value to be started; as well as Starting from sending the information for triggering CSI reporting, performing a monitoring operation within a time period corresponding to the delay limit value to receive the SL CSI of the second terminal, wherein the timer is started in response to the CSI report being triggered by the SCI, and If the timer expires, the triggered CSI report is canceled; otherwise, the SL CSI is sent to the first terminal. 2 . The method according to claim 1 , further comprising, when the SL CSI of the second terminal is not received within the time period, retransmitting the information for triggering CSI reporting.

3. The method according to claim 2, wherein: In response to the information for triggering the CSI report being retransmitted, a reset delay limit value is used to replace the delay limit value, and the reset delay limit value is greater than or less than the delay limit value.

4. The method according to claim 1, wherein The delay limit value is set specifically for the side link.

5. The method according to claim 1, wherein The delay limit value is set in units of time slots.

6. The method according to claim 1, wherein The delay limit value is a time offset from the time when the information for triggering the CSI report is sent.

7. The method according to claim 1, wherein The delay limit value is set independently of the type of the SL CSI, and the type of the SL CSI varies according to information included in the SL CSI.

8. The method according to claim 1, wherein The SL CSI includes a channel quality indicator (CQI) and a rank indicator (RI).

9. A method for operating a second terminal in a communication system, the method comprising the steps of: Receiving a radio resource control message (RRC message) from the first terminal, the RRC message including information indicating a delay limit value of a time slot number for a side link (SL) channel state information (CSI) report; receiving sidelink control information (SCI) from the first terminal, where the SCI includes information for triggering the CSI report; In response to triggering the CSI report, starting a timer associated with the delay limit value; If the timer expires, canceling the CSI report triggered by the SCI; Otherwise, starting from the time when the information for triggering the CSI report is received, the SL CSI report is sent to the first terminal within a time period corresponding to the delay limit value.

10. The method according to claim 9, wherein: When the time period ends, the SL CSI is not sent to the first terminal.

11. The method according to claim 9, wherein The delay limit value is set specifically for the side link.

12. The method according to claim 9, wherein The delay limit value is set in units of time slots and starts from the time when the information for triggering the CSI report is received.

13. The method according to claim 9, wherein: The delay limit value is set independently of the type of the SL CSI, and the type of the SL CSI varies according to information included in the SL CSI.

14. The method according to claim 9, wherein The SL CSI includes a channel quality indicator (CQI) and a rank indicator (RI).

15. A first terminal in a communication system, the first terminal comprising: processor; as well as a memory storing at least one instruction to be executed by the processor, The at least one instruction is executed to: Sending information indicating a delay limit value of a sidelink channel state information report (SL CSI report) to the second terminal; Sending sidelink control information (SCI) to the second terminal, the SCI including information for triggering CSI reporting, wherein the information for triggering CSI reporting causes a timer associated with the delay limit value to be started; and Starting from sending the information for triggering CSI reporting, performing a monitoring operation within a time period corresponding to the delay limit value to receive the SL CSI of the second terminal, wherein the timer is started in response to the CSI report being triggered, and If the timer expires, the CSI report is canceled; otherwise, the SLCSI is sent to the first terminal.

16. A second terminal in a communication system, the second terminal comprising: processor; as well as a memory storing at least one instruction to be executed by the processor, Wherein, the at least one instruction is executed to: Receiving a radio resource control message (RRC message) from the first terminal, the RRC message including information indicating a delay limit value of a time slot number for a side link (SL) channel state information (CSI) report; receiving sidelink control information (SCI) from the first terminal, where the SCI includes information for triggering the CSI report; In response to triggering the CSI report, starting a timer associated with the delay limit value; If the timer expires, canceling the CSI report triggered by the SCI; Otherwise, starting from the time when the information for triggering the CSI report is received, SL CSI is sent to the first terminal within a time period corresponding to the delay limit value.

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