Method and apparatus for sidelink communication based on start location in unlicensed band

Abstract

Methods and apparatus for sidelink communication based on a start location in an unlicensed band are disclosed. The method of a first UE comprises the steps of: receiving configuration information on a start symbol from a base station; identifying a plurality of start symbols based on the configuration information; performing a first LBT operation from a first start symbol of the plurality of start symbols in the first time slot; if the first LBT operation at the first start symbol fails, a second LBT operation is performed from a second start symbol of the plurality of start symbols in the first slot.

Description

Technical Field

[0001] The present invention relates to a sidelink communication technology, and more specifically, to a sidelink communication technology based on multiple start positions. Background Art

[0002] Communication networks (e.g., 5G communication networks or 6G communication networks) are being developed to provide enhanced communication services compared to existing communication networks (e.g., long term evolution (LTE), LTE-Advanced, etc.). A 5G communication network (e.g., a New Radio (NR) communication network) can support frequency bands below 6 GHz and above 6 GHz. In other words, a 5G communication network can support Frequency Range 1 (FR1) bands and / or FR2 bands. Compared to an LTE communication network, a 5G communication network can support various communication services and scenarios. For example, the usage scenarios of a 5G communication network can include enhanced Mobile BroadBand (eMBB), UltraReliable Low Latency Communication (URLLC), massive MachineType Communication (mMTC), etc.

[0003] Compared to a 5G communication network, a 6G communication network can support a wide variety of communication services and scenarios. A 6G communication network can meet the requirements of super performance, super bandwidth, super space, super precision, super intelligence, and / or super reliability. A 6G communication network can support multiple wide frequency bands and can be applied to various usage scenarios, such as terrestrial communication, non-terrestrial communication, sidelink communication, etc.

[0004] On the other hand, in order to enhance sidelink communication, carrier aggregation (CA) operations, unlicensed band operations, FR2 band operations, and / or operations for coexistence between LTE and NR can be considered. In particular, when performing sidelink communication in an unlicensed band, a method for supporting sidelink communication may be required. For operations in an unlicensed band, optimization of the sidelink physical channel structure may be required. In addition, improvement of the listen before talk (LBT) operation for sidelink communication in an unlicensed band may be required. Summary of the Invention

[0005] Technical Problem

[0006] The present invention aims to provide a method and apparatus for sidelink communication based on multiple start positions in an unlicensed band.

[0007] Technical solution

[0008] A method for a first user equipment (UE) according to an exemplary embodiment of the present invention for achieving the above object may include: receiving configuration information of start symbols from a base station; identifying a plurality of start symbols based on the configuration information; performing a first listen-before-talk (LBT) operation on a first start symbol among the plurality of start symbols in a first time slot; and performing a second LBT operation on a second start symbol among the plurality of start symbols in the first time slot based on a failure of the first LBT operation in the first start symbol, wherein the first LBT operation and each of the second LBT operations may be performed on a sidelink (SL) transmission to a second UE, and the second start symbol may be located after the first start symbol in the time domain.

[0009] In the first time slot, the second start symbol may be configured as a symbol other than a physical sidelink shared channel (PSSCH) demodulation reference signal (DMRS) symbol, and the PSSCH DMRS symbol may be a symbol for transmitting DMRS for demodulation of the PSSCH.

[0010] In the first time slot, the second start symbol may be configured as a symbol before or after the PSSCH DMRS symbol.

[0011] In the first time slot, the second start symbol may be configured as the PSSCH DMRS symbol.

[0012] In the first time slot, the PSSCH DMRS symbol may be configured considering at least one of the number or position of the plurality of start symbols.

[0013] When the second LBT operation is successful, an SL transmission may be performed in the first time slot, and when the second LBT operation fails, an SL transmission may be performed in a second time slot after the first time slot.

[0014] A copy of data to be transmitted in the next symbol of the second start symbol may be sent in the second start symbol.

[0015] The configuration information may include information indicating the position of the first start symbol and information indicating the position of the second start symbol.

[0016] The information indicating the position of the second start symbol may be a symbol offset between the first start symbol and the second start symbol.

[0017] When the use of a plurality of start symbols is enabled, the second LBT operation may be performed in the second start symbol, and when the use of a plurality of start symbols is disabled, the second LBT operation may not be performed in the second start symbol.

[0018] A method for a second User Equipment (UE) according to an exemplary embodiment of the present invention for achieving the above object may include: receiving configuration information of start symbols from a base station; identifying a plurality of start symbols based on the configuration information; performing a first monitoring operation for a sidelink (SL) transmission for a first UE according to a first Listen Before Talk (LBT) operation in a first start symbol of the plurality of start symbols within a first time slot; and in response to a reception failure of the SL transmission according to the first LBT operation, performing a second monitoring operation for the SL transmission for the first UE according to a second LBT operation in a second start symbol of the plurality of start symbols within the first time slot, wherein the second start symbol may be located after the first start symbol in the time domain.

[0019] Within the first time slot, the second start symbol may be configured as a symbol other than a Physical Sidelink Shared Channel (PSSCH) Demodulation Reference Signal (DMRS) symbol, and the PSSCH DMRS symbol may be a symbol for transmitting DMRS for demodulation of the PSSCH.

[0020] Within the first time slot, the second start symbol may be configured as a symbol before or after the PSSCH DMRS symbol.

[0021] Within the first time slot, the second start symbol may be configured as the PSSCH DMRS symbol.

[0022] Within the first time slot, the PSSCH DMRS symbol may be configured considering at least one of the number or position of the plurality of start symbols.

[0023] When there is a reception failure of the SL transmission according to the second LBT operation, the second UE may not expect to receive an SL transmission within the first time slot, and the SL transmission may be delayed to a second time slot after the first time slot.

[0024] A copy of data to be received in the next symbol of the second start symbol may be received in the second start symbol.

[0025] The configuration information may include information indicating the position of the first start symbol and information indicating the position of the second start symbol.

[0026] The information indicating the position of the second start symbol may be a symbol offset between the first start symbol and the second start symbol.

[0027] When the use of a plurality of start symbols is enabled, the second LBT operation may be performed in the second start symbol, and when the use of a plurality of start symbols is disabled, the second LBT operation may not be performed in the second start symbol.

[0028] Beneficial effects

[0029] According to the present invention, a plurality of start symbols can be configured for a terminal used for sidelink unauthorized (SL-U) communication. The transmitting terminal can perform a LBT operation in the initial start symbol. If the LBT operation fails in the initial start symbol, the transmitting terminal can perform a LBT operation in the additional start symbol. If the LBT operation is successful, the transmitting terminal can perform an SL transmission. Since a plurality of start symbols can be configured within a single time slot, delays in SL transmission can be prevented, and the performance of SL-U communication can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 is a conceptual diagram showing a scenario of vehicle-to-everything (V2X) communication.

[0031] Figure 2 is a conceptual diagram showing a first exemplary embodiment of a communication system.

[0032] Figure 3 is a conceptual diagram showing a first exemplary embodiment of a communication node constituting a communication system.

[0033] Figure 4 is a block diagram showing a first exemplary embodiment of a communication node performing communication.

[0034] Figure 5a is a block diagram showing a first exemplary embodiment of a transmission path.

[0035] Figure 5b is a block diagram showing a first exemplary embodiment of a reception path.

[0036] Figure 6 is a block diagram showing a first exemplary embodiment of a user plane protocol stack of a UE performing sidelink communication.

[0037] Figure 7 is a block diagram showing a first exemplary embodiment of a control plane protocol stack of a UE performing sidelink communication.

[0038] Figure 8 is a block diagram showing a second exemplary embodiment of a control plane protocol stack of a UE performing sidelink communication.

[0039] Figure 9 is a timing diagram showing a first exemplary embodiment of a communication method in an unauthorized frequency band.

[0040] Figure 10 is a conceptual diagram showing a first exemplary embodiment of a LBT operation in SL-U communication.

[0041] Figure 11 is a conceptual diagram showing a second exemplary embodiment of a LBT operation in SL-U communication.

[0042] Figure 12 is a conceptual diagram showing a third exemplary embodiment of the LBT operation in SL-U communication.

[0043] Figure 13 is a conceptual diagram showing a fourth exemplary embodiment of the LBT operation in SL-U communication. Detailed Description

[0044] Since the present invention can be modified in various ways and can have various forms, specific exemplary embodiments will be shown in the drawings and described in detail in the detailed description. However, it should be understood that the present invention is not intended to be limited to the specific exemplary embodiments, but on the contrary, the present invention covers all modifications and alternative forms falling within the spirit and scope of the present invention.

[0045] Relational terms such as first, second, etc. may be used to describe various elements, but these elements should not be limited by the terms. These terms are only used to distinguish one element from another. For example, without departing from the scope of the present invention, the first component may be named the second component, and the second component may be similarly named the first component. The term "and / or" means any one or combination of a plurality of related and described matters.

[0046] In the present invention, "at least one of A and B" may refer to "at least one of A or B" or "at least one of a combination of one or more of A and B". In addition, "one or more of A and B" may refer to "one or more of A or B" or "one or more of a combination of one or more of A and B".

[0047] In the present invention, "(re)transmission" may refer to "transmission", "retransmission" or "transmission and retransmission", "(re)configuration" may refer to "configuration", "reconfiguration" or "configuration and reconfiguration", "(re)connection" may refer to "connection", "reconnection" or "connection and reconnection", and "(re)access" may refer to "access", "reaccess" or "access and reaccess".

[0048] When it is mentioned that a certain component is "coupled" or "connected" to another component, it should be understood that the certain component is directly "coupled" or "connected" to the other component, or additional components may be provided therebetween. On the contrary, when it is mentioned that a certain component is "directly coupled" or "directly connected" to another component, it should be understood that no additional components are provided therebetween.

[0049] The terms used in this invention are only for describing specific exemplary embodiments and are not intended to limit the invention. Singular expressions include plural expressions unless the context clearly dictates otherwise. In this invention, terms such as "including" or "having" are intended to indicate the presence of the features, quantities, steps, operations, components, parts, or combinations thereof described in the specification. However, it should be understood that these terms do not preclude the presence or addition of one or more features, quantities, steps, operations, components, parts, or combinations thereof.

[0050] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Terms commonly used in a dictionary and already in the dictionary should be interpreted as having a meaning that matches the contextual meaning in the art. In this specification, terms are not necessarily to be interpreted as having a formal meaning unless clearly defined.

[0051] Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the drawings. When describing the present invention, for the sake of a comprehensive understanding of the present invention, the same reference numerals refer to the same elements throughout the description of the drawings, and repeated descriptions thereof will be omitted. Operations according to the exemplary embodiments clearly described in the present invention, combinations of exemplary embodiments, extensions of exemplary embodiments, and / or variant forms of exemplary embodiments can be performed. Some operations may be omitted, and the order of operations may be changed.

[0052] Even when describing a method (e.g., transmission or reception of a signal) performed at a first communication node in a communication node in an exemplary embodiment, 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). That is, when describing the operation of a user equipment (UE), the corresponding base station may perform an operation corresponding to the operation of the UE. Conversely, when describing the operation of a base station, the corresponding UE may perform an operation corresponding to the operation of the base station.

[0053] A base station can be referred to by various terms, such as Node B, evolved Node B, next-generation Node B (gNodeB), gNB, device, apparatus, node, communication node, base transceiver station (BTS), radio remote head (RRH), transmission reception point (TRP), radio unit (RU), roadside unit (RSU), radio transceiver, access point, access node, etc. A user equipment (UE) can be referred to by various terms, such as terminal, device, apparatus, node, communication node, end node, access terminal, mobile terminal, station, subscriber station, mobile station, portable subscriber station, on-board unit (OBU), etc.

[0054] In the present invention, the signaling can be one of higher-layer signaling, MAC signaling, and physical (PHY) signaling, or a combination of two or more of them. A message for higher-layer signaling can be referred to as a "higher-layer message" or a "higher-layer signaling message". A message for MAC signaling can be referred to as a "MAC message" or a "MAC signaling message". A message for PHY signaling can be referred to as a "PHY message" or a "PHY signaling message". Higher-layer signaling can 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 can refer to the operation of sending and receiving MAC control elements (CE). PHY signaling can refer to the operation of sending and receiving control information (e.g., downlink control information (DCI), uplink control information (UCI), or sidelink control information (SCI)).

[0055] In the present invention, the "configuration of an operation (e.g., a transmission operation)" can refer to the configuration information (e.g., information element, parameter) required for the operation and / or the signaling indicating the information for performing the operation. The "configuration of an information element (e.g., a parameter)" can refer to the signaling of the information element. In the present invention, "signal and / or channel" can refer to a signal, a channel, or both a signal and a channel, and "signal" can be used to mean "signal and / or channel".

[0056] The communication network applying the exemplary embodiments is not limited to the communication network described below, and the exemplary embodiments can be applied to various communication networks (e.g., 4G communication network, 5G communication network, and / or 6G communication network). Herein, the "communication network" can be used interchangeably with the term "communication system".

[0057] Figure 1 is a conceptual diagram showing a scenario of Vehicle-to-Everything (V2X) communication.

[0058] As Figure 1 shown, V2X communication can include Vehicle-to-Vehicle (V2V) communication, Vehicle-to-Infrastructure (V2I) communication, Vehicle-to-Pedestrian (V2P) communication, Vehicle-to-Network (V2N) communication, etc. V2X communication can be supported by a communication system (e.g., a communication network) 140, and the V2X communication supported by the communication system 140 can be referred to as "Cellular-V2X (C-V2X) communication". Herein, the communication system 140 can 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.

[0059] V2V communication can 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, forward direction, time, position, etc. can be exchanged between the vehicle 100 and the vehicle 110 through V2V communication. For example, autonomous driving (e.g., platooning) can be supported based on the driving information exchanged through V2V communication. The V2V communication supported by the communication system 140 can be performed based on sidelink communication technologies (e.g., Proximity Based Services (ProSe) and Device-to-Device (D2D) communication technologies, etc.). In this case, at least one sidelink channel can be utilized to perform communication between the vehicle 100 and the vehicle 110.

[0060] V2I communication may include communication between a first vehicle 100 and infrastructure located on the roadside (e.g., a roadside unit (RSU)) 120. The infrastructure 120 may include traffic lights or street lights located on the roadside. For example, when performing V2I communication, communication may be performed between a communication node in the first vehicle 100 and a communication node in the traffic light. Traffic information, driving information, etc. may be exchanged between the first vehicle 100 and the infrastructure 120 through V2I communication. V2I communication supported by the communication system 140 may be performed based on sidelink communication technologies (e.g., ProSe and D2D communication technologies, etc.). In this case, at least one sidelink channel may be utilized to perform communication between the vehicle 100 and the infrastructure 120.

[0061] V2P communication may include communication between a first vehicle 100 (e.g., a communication node in the vehicle 100) and a person 130 (e.g., a communication node carried by the person 130). Driving information of the first vehicle 100 and movement information of the person 130, such as speed, forward direction, time, location, etc., may be exchanged between the vehicle 100 and the person 130 through V2P communication. By judging a dangerous situation based on the obtained driving information and movement information, the communication node in the vehicle 100 or the communication node carried by the person 130 may generate an alarm indicating danger. V2P communication supported by the communication system 140 may be performed based on sidelink communication technologies (e.g., ProSe and D2D communication technologies, etc.). In this case, at least one sidelink channel may be utilized to perform communication between the communication node in the vehicle 100 and the communication node carried by the person 130.

[0062] V2N communication may be communication between a first vehicle 100 (e.g., a communication node in the vehicle 100) and a communication system (e.g., a communication network) 140. V2N communication may be performed based on 4G communication technologies (e.g., LTE or LTE-A as described in the 3GPP standard) or 5G communication technologies (e.g., NR as described in the 3GPP standard). In addition, V2N communication may be performed based on Wireless Access in Vehicular Environments (WAVE) communication technologies or wireless local area network (WLAN) communication technologies defined in Institute of Electrical and Electronics Engineers (IEEE) 802.11, wireless personal area network (WPAN) communication technologies defined in IEEE 802.15, etc.

[0063] On the other hand, the communication system 140 that supports V2X communication can be configured as follows.

[0064] Figure 2 It is a conceptual diagram showing a first exemplary embodiment of the communication system.

[0065] As Figure 2 shown, the communication system may include an access network, a core network, etc. The access network may include base stations 210, relay stations 220, user equipments (UEs) 231 to 236, etc. The UEs 231 to 236 may include communication nodes in vehicles 100 and 110 located at Figure 1 , communication nodes in infrastructure 120 located at Figure 1 , communication nodes carried by a person 130 located at Figure 1 , etc. When the 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, etc.

[0066] When the 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 communication system operates in a Non-Stand Alone (NSA) mode, the core network composed of the S-GW 250, the P-GW 260, and the MME 270 may support both 5G communication technology and 4G communication technology, and the core network composed of the UPF 250, the SMF 260, and the AMF 270 may support both 4G communication technology and 5G communication technology.

[0067] In addition, when the communication system supports network slicing technology, the core network can be divided into multiple logical network slices. For example, a network slice that supports V2X communication (such as a V2V network slice, a V2I network slice, a V2P network slice, a V2N network slice, etc.) can be configured, and V2X communication can be supported through the V2X network slice configured in the core network.

[0068] Communication nodes (e.g., base stations, relay stations, UEs, S-GWs, P-GWs, MMEs, UPFs, SMFs, AMFs, etc.) that make up a communication system can perform communication by 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 (UFMC) technology, and space division multiple access (SDMA) technology.

[0069] Communication nodes (e.g., base stations, relay stations, UEs, S-GWs, P-GWs, MMEs, UPFs, SMFs, AMFs, etc.) that make up a communication system can be configured as follows.

[0070] Figure 3 It is a conceptual diagram showing a first exemplary embodiment of a communication node that makes up a communication system.

[0071] As Figure 3 shown, the communication node 300 can 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 can 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 can communicate with each other when connected via a bus 370.

[0072] However, each component included in the communication node 300 may be connected to the processor 310 via a separate interface or a separate bus rather than 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 via a dedicated interface.

[0073] The processor 310 may execute at least one program 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 on which the method according to an exemplary embodiment of the present invention is executed. 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).

[0074] Referring again to Figure 2 , in the communication system, the base station 210 may form a macro cell or a small cell and may be connected to the core network via an ideal backhaul or a non-ideal backhaul. The base station 210 may send the signals received from the core network to the UEs 231 to 236 and the relay station 220, and may send the signals received from the UEs 231 to 236 and the relay station 220 to the core network. The UE#1 231, the UE#2 232, the UE#4 234, the UE#5 235, and the UE#6 236 may belong to the cell coverage area of the base station 210. The UE#1 231, the UE#2 232, the UE#4 234, the UE#5 235, and the UE#6 236 may be connected to the base station 210 by performing a connection establishment process with the base station 210. The UE#1 231, the UE#2 232, the UE#4 234, the UE#5 235, and the UE#6 236 may communicate with the base station 210 after being connected to the base station 210.

[0075] The relay station 220 can be connected to the base station 210 and can relay the communication between the base station 210 and UE#3 233 and UE#4 234. That is, the relay station 220 can send the signals received from the base station 210 to UE#3 233 and UE#4 234, and can send the signals received from UE#3 233 and UE#4 234 to the base station 210. UE#4 234 can belong to both the cell coverage of the base station 210 and the cell coverage of the relay station 220, and UE#3 233 can belong to the cell coverage of the relay station 220. That is, UE#3 233 can be located outside the cell coverage of the base station 210. UE#3 233 and UE#4 234 can be connected to the relay station 220 by performing a connection establishment process with the relay station 220. UE#3 233 and UE#4 234 can communicate with the relay station 220 after being connected to the relay station 220.

[0076] The base station 210 and the relay station 220 can support multiple-input multiple-output (MIMO) technologies (e.g., single-user (SU)-MIMO, multi-user (MU)-MIMO, massive MIMO, etc.), coordinated multipoint (CoMP) communication technologies, carrier aggregation (CA) communication technologies, unlicensed band communication technologies (e.g., Licensed Assisted Access (LAA), enhanced LAA (eLAA), etc.), sidelink communication technologies (e.g., ProSe communication technology, D2D communication technology), etc. UE#1 231, UE#2 232, UE#5 235, and UE#6 236 can perform operations corresponding to the base station 210 and operations supported by the base station 210. UE#3 233 and UE#4 234 can perform operations corresponding to the relay station 220 and operations supported by the relay station 220.

[0077] Herein, the base station 210 can refer to a Node B (NB), an evolved Node B (eNB), a base transceiver station (BTS), a radio remote head (RRH), a transmit receive point (TRP), a radio unit (RU), a roadside unit (RSU), a radio transceiver, an access point, an access node, etc. The relay station 220 can refer to a small base station, a relay node, etc. Each of UE 231 to UE 236 can refer to 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-board unit (OBU), etc.

[0078] On the other hand, communication nodes performing communication in a communication network can be configured as follows. Figure 4The communication node shown may be Figure 3 a specific exemplary implementation of the communication node shown.

[0079] Figure 4 is a block diagram showing a first exemplary implementation of a communication node that performs communication.

[0080] As Figure 4 shown, each of the first communication node 400a and the second communication node 400b may be a base station or a UE. The first communication node 400a may send a signal to the second communication node 400b. The transmission processor 411 included in the first communication node 400a may receive data (e.g., data units) from the data source 410. The transmission processor 411 may receive control information from the controller 416. The control information may include at least one of system information, RRC configuration information (e.g., information configured by RRC signaling), MAC control information (e.g., MAC CE), or PHY control information (e.g., DCI, SCI).

[0081] The transmission processor 411 may generate data symbols by performing processing operations on the data (e.g., encoding operations, symbol mapping operations, etc.). The transmission processor 411 may generate control symbols by performing processing operations on the control information (e.g., encoding operations, symbol mapping operations, etc.). In addition, the transmission processor 411 may generate synchronization / reference symbols for synchronization signals and / or reference signals.

[0082] The Tx MIMO processor 412 may perform spatial processing operations (e.g., precoding operations) on the data symbols, control symbols, and / or synchronization / reference symbols. The output of the Tx MIMO processor 412 (e.g., symbol stream) may be provided to the modulators (MOD) included in the transceivers 413a to 413t. The modulator may generate modulated symbols by performing processing operations on the symbol stream, and may generate signals by performing additional processing operations on the modulated symbols (e.g., analog conversion operations, amplification operations, filtering operations, upconversion operations, etc.). The signals generated by the modulators of the transceivers 413a to 413t may be transmitted through the antennas 414a to 414t.

[0083] The signal transmitted by the first communication node 400a can be received at antennas 464a to 464r of the second communication node 400b. The signals received at antennas 464a to 464r can be provided to a demodulator (DEMOD) included in transceivers 463a to 463r. The demodulator (DEMOD) can obtain samples by performing processing operations on the signals (e.g., filtering operations, amplification operations, down-conversion operations, digital conversion operations, etc.). The demodulator can perform additional processing operations on the samples to obtain symbols. The MIMO detector 462 can perform MIMO detection operations on the symbols. The receive processor 461 can perform processing operations on the symbols (e.g., deinterleaving operations, decoding operations, etc.). The output of the receive processor 461 can be provided to the data sink 460 and the controller 466. For example, data can be provided to the data sink 460, and control information can be provided to the controller 466.

[0084] On the other hand, the second communication node 400b can send a signal to the first communication node 400a. The transmit processor 468 included in the second communication node 400b can receive data (e.g., data units) from the data source 467 and perform processing operations on the data to generate data symbols. The transmit processor 468 can receive control information from the controller 466 and perform processing operations on the control information to generate control symbols. In addition, the transmit processor 468 can generate reference symbols by performing processing operations on reference signals.

[0085] The Tx MIMO processor 469 can perform spatial processing operations (e.g., precoding operations) on the data symbols, control symbols, and / or reference symbols. The output of the Tx MIMO processor 469 (e.g., symbol stream) can be provided to a modulator (MOD) included in transceivers 463a to 463t. The modulator can generate modulated symbols by performing processing operations on the symbol stream and can generate signals by performing additional processing operations on the modulated symbols (e.g., analog conversion operations, amplification operations, filtering operations, up-conversion operations). The signals generated by the modulators of transceivers 463a to 463t can be transmitted through antennas 464a to 464t.

[0086] The signal transmitted by the second communication node 400b can be received at antennas 414a to 414r of the first communication node 400a. The signal received at antennas 414a to 414r can be provided to a demodulator (DEMOD) included in transceivers 413a to 413r. The demodulator can obtain samples by performing processing operations on the signal (e.g., filtering operation, amplification operation, down-conversion operation, digital conversion operation). The demodulator can perform additional processing operations on the samples to obtain symbols. The MIMO detector 420 can perform MIMO detection operations on the symbols. The receive processor 419 can perform processing operations on the symbols (e.g., deinterleaving operation, decoding operation, etc.). The output of the receive processor 419 can be provided to the data sink 418 and the controller 416. For example, data can be provided to the data sink 418, and control information can be provided to the controller 416.

[0087] The memories 415 and 465 can store data, control information, and / or program code. The scheduler 417 can perform scheduling operations for communication. Figure 4 The illustrated processors 411, 412, 419, 461, 468, and 469 and the controllers 416 and 466 can be Figure 3 the illustrated processor 310 and can be used to execute the methods described in the present invention.

[0088] Figure 5a is a block diagram showing a first exemplary embodiment of a transmission path, Figure 5b is a block diagram showing a first exemplary embodiment of a reception path.

[0089] As Figure 5a and Figure 5bAs shown, a transmission path 510 can be implemented in a communication node that transmits signals, and a reception path 520 can be implemented in a communication node that receives signals. The transmission path 510 can include a channel coding and modulation block 511, a serial-to-parallel (S-to-P) block 512, an N-point inverse fast Fourier transform (N-point IFFT) block 513, a parallel-to-serial (P-to-S) block 514, a cyclic prefix (CP) addition block 515, and an up-converter (UC) 516. The reception path 520 can include a down-converter (DC) 521, a CP removal block 522, an S-to-P block 523, an N-point FFT block 524, a P-to-S block 525, and a channel decoding and demodulation block 526. Here, N can be a natural number.

[0090] In the transmission path 510, information bits can be input to the channel coding and modulation block 511. The channel coding and modulation block 511 can perform encoding / decoding operations on the information bits (e.g., low-density parity check (LDPC) encoding / decoding operations, polar encoding / decoding operations, etc.) and modulation operations (e.g., Quadrature Phase Shift Keying (QPSK), Quadrature Amplitude Modulation (QAM), etc.). The output of the channel coding and modulation block 511 can be a modulated symbol sequence.

[0091] The S-to-P block 512 can convert the frequency-domain modulated symbols into a parallel symbol stream to generate N parallel symbol streams. N can be the IFFT size or the FFT size. The N-point IFFT block 513 can generate a time-domain signal by performing an IFFT operation on the N parallel symbol streams. The P-to-S block 514 can convert the output of the N-point IFFT block 513 (e.g., the parallel signal) into a serial signal to generate a serial signal.

[0092] The CP addition block 515 can insert a CP into the signal. The UC 516 can up-convert the frequency of the output of the CP addition block 515 to a radio frequency (RF) frequency. In addition, the output of the CP addition block 515 can be filtered in the baseband before up-conversion.

[0093] The signal transmitted from the transmission path 510 can be input to the reception path 520. The operations in the reception path 520 can be the reverse operations of those in the transmission path 510. The DC 521 can down-convert the frequency of the received signal to the baseband frequency. The CP removal block 522 can remove the CP from the signal. The output of the CP removal block 522 can be a serial signal. The S-to-P block 523 can convert the serial signal into a parallel signal. The N-point FFT block 524 can generate N parallel signals by performing the FFT algorithm. The P-to-S block 525 can convert the parallel signal into a modulated symbol sequence. The channel decoding and demodulation block 526 can perform the demodulation operation on the modulated symbols and can recover the data by performing the decoding operation on the result of the demodulation operation.

[0094] In Figure 5a and Figure 5b the discrete Fourier transform (DFT) and the inverse DFT (IDFT) can be used instead of the FFT and the IFFT. Figure 5a and Figure 5b each of the blocks (e.g., components) in Figure 5a and Figure 5b can be implemented by at least one of hardware, software, or firmware. For example, Figure 5a and Figure 5b some of the blocks in

[0095] On the other hand, the communication between UE#5 235 and UE#6 236 can be performed based on sidelink communication technologies (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 performing V2V communication using the sidelink communication technology, UE#5 235 can refer to the communication node in the first vehicle 100 located in Figure 1 and UE#6 236 can refer to the communication node in the second vehicle 110 located in Figure 1 When performing V2I communication using the sidelink communication technology, UE#5 235 can refer to the communication node in the first vehicle 100 located in Figure 1 and UE#6236 can refer to the communication node in the infrastructure 120 located in Figure 1 When performing V2P communication using the sidelink communication technology, UE#5 235 can refer to the communication node in the first vehicle 100 located in Figure 1a communication node in the first vehicle 100, and UE#6 236 can refer to a communication node carried by a person 130.

[0096] The scenarios of applying sidelink communication can be classified according to the locations of the UEs (e.g., UE#5 235 and UE#6 236) participating in the sidelink communication, as shown in Table 1 below. For example, Figure 2 The scenario of sidelink communication between UE#5 235 and UE#6 236 shown can be sidelink communication scenario #C.

[0097] [Table 1]

[0098]

[0099]

[0100] On the other hand, the user plane protocol stacks of the UEs (e.g., UE#5 235 and UE#6 236) performing sidelink communication can be configured as follows.

[0101] Figure 6 is a block diagram showing a first exemplary embodiment of the user plane protocol stack of a UE performing sidelink communication.

[0102] As Figure 6 shown, UE#5 235 can be Figure 2 UE#5 235 shown, and UE#6 236 can be Figure 2 UE#6 236 shown. The scenario of sidelink communication between UE#5 235 and UE#6 236 can be one of sidelink communication scenarios #A to #D in Table 1. The user plane protocol stack of each of UE#5 235 and UE#6 236 can include a physical (PHY) layer, a medium access control (MAC) layer, a radio link control (RLC) layer, and a packet data convergence protocol (PDCP) layer.

[0103] The side - link communication between UE#5 235 and UE#6 236 can be performed using the PC5 interface (e.g., PC5 - U interface). The second - layer identifier (ID) (e.g., source second - layer ID, destination second - layer ID) can be used for side - link communication, and the second - layer ID can be an ID configured for V2X communication. In addition, in side - link communication, hybrid automatic repeat request (HARQ) feedback operations can be supported, and RLC acknowledged mode (AM) or RLC unacknowledged mode (UM) can be supported.

[0104] On the other hand, the control - plane protocol stack of the UEs (e.g., UE#5 235 and UE#6 236) performing side - link communication can be configured as follows.

[0105] Figure 7 is a block diagram showing a first exemplary embodiment of the control - plane protocol stack of a UE performing side - link communication, Figure 8 is a block diagram showing a second exemplary embodiment of the control - plane protocol stack of a UE performing side - link communication.

[0106] As Figure 7 and Figure 8 shown, UE#5 235 can be the Figure 2 UE#5 235 shown, and UE#6 236 can be the Figure 2 UE#6 236 shown. The scenario of the side - link communication between UE#5 235 and UE#6 236 can be one of side - link communication scenarios #A to #D in Table 1. Figure 7 The control - plane protocol stack shown can be a control - plane protocol stack for sending and receiving broadcast information (e.g., Physical Sidelink Broadcast Channel (PSBCH)).

[0107] Figure 7 The control - plane protocol stack shown can include a PHY layer, a MAC layer, an RLC layer, and a Radio Resource Control (RRC) layer. The side - link communication between UE#5 235 and UE#6 236 can be performed using the PC5 interface (e.g., PC5 - C interface). Figure 8 The control - plane protocol stack shown can be a control - plane protocol stack for one - to - one side - link communication. Figure 8 The control - plane protocol stack shown can include a PHY layer, a MAC layer, an RLC layer, a PDCP layer, and a PC5 signaling protocol layer.

[0108] On the other hand, the channels utilized in the sidelink communication between UE#5 235 and UE#6 236 may include Physical Sidelink Shared Channel (PSSCH), Physical Sidelink Control Channel (PSCCH), Physical Sidelink Discovery Channel (PSDCH), and 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.

[0109] The PSDCH may be used for the discovery process. For example, discovery signals may be transmitted through the PSDCH. The PSBCH may be used to transmit and receive broadcast information (e.g., system information). In addition, demodulation reference signal (DM-RS), synchronization signals, etc. may be utilized in the sidelink communication between UE#5 235 and UE#6 236. The synchronization signals may include primary sidelink synchronization signal (PSSS) and secondary sidelink synchronization signal (SSSS).

[0110] On the other hand, the sidelink transmission mode (TM) may be divided into sidelink TM#1 to TM#4 as shown in Table 2 below.

[0111] [Table 2]

[0112] Sidelink TM Description #1 Transmission using resources scheduled by the base station #2 UE autonomous transmission without base station scheduling #3 Transmission using resources scheduled by the base station in V2X communication #4 UE autonomous transmission without base station scheduling in V2X communication

[0113] When sidelink TM#3 or TM#4 is supported, each of UE#5 235 and UE#6 236 may utilize a resource pool configured by the base station 210 to perform sidelink communication. Resource pools may be configured for each of the sidelink control information and sidelink data.

[0114] The resource pool for sidelink control information can be configured based on the RRC signaling procedure (e.g., dedicated RRC signaling procedure, broadcast RRC signaling procedure). The resource pool for receiving sidelink control information can be configured through the broadcast RRC signaling procedure. When sidelink TM#3 is supported, the resource pool for transmitting sidelink control information can be configured through the dedicated RRC signaling procedure. In this case, the sidelink control information can be transmitted via the resources scheduled by the base station 210 within the resource pool configured through the dedicated RRC signaling procedure. When sidelink TM#4 is supported, the resource pool for transmitting sidelink control information can be configured through the dedicated RRC signaling procedure or the broadcast RRC signaling procedure. In this case, the sidelink control information can be transmitted via the resources automatically selected by the UE (e.g., UE#5 235 or UE#6 236) within the resource pool configured through the dedicated RRC signaling procedure or the broadcast RRC signaling procedure.

[0115] When sidelink TM#3 is supported, the resource pool for sending and receiving sidelink data may not be configured. In this case, the sidelink data can be sent and received through the resources scheduled by the base station 210. When sidelink TM#4 is supported, the resource pool for sending and receiving sidelink data can be configured through the dedicated RRC signaling procedure or the broadcast RRC signaling procedure. In this case, the sidelink data can be sent and received via the resources automatically selected by the UE (e.g., UE#5 235 or UE#6 236) within the resource pool configured through the dedicated RRC signaling procedure or the broadcast RRC signaling procedure.

[0116] Hereinafter, the sidelink communication method will be described. Even when describing the method (e.g., transmission or reception of signals) performed at the first communication node among the communication nodes, the corresponding second communication node may also perform the method corresponding to the method performed at the first communication node (e.g., reception or transmission of signals). That is, when describing the operation of UE#1 (e.g., vehicle#1), the corresponding UE#2 (e.g., vehicle#2) can perform the operation corresponding to the operation of UE#1. Conversely, when describing the operation of UE#2, the corresponding UE#1 can perform the operation corresponding to the operation of UE#2. In the exemplary embodiments described below, the operation of the vehicle may be the operation of the communication node located in the vehicle.

[0117] The sidelink signal can be a synchronization signal and a reference signal for sidelink communication. For example, the synchronization signal can be a synchronization signal / physical broadcast channel (SS / PBCH) block, a sidelink synchronization signal (SLSS), a primary sidelink synchronization signal (PSSS), a secondary sidelink synchronization signal (SSSS), etc. The reference signal can be a channel state information-reference signal (CSI-RS), a DM-RS, a phase tracking-reference signal (PT-RS), a cell specific reference signal (CRS), a sounding reference signal (SRS), a discovery reference signal (DRS), etc.

[0118] The sidelink channel can be a PSSCH, a PSCCH, a PSDCH, a PSBCH, a physical sidelink feedback channel (PSFCH), etc. In addition, the sidelink channel can refer to a sidelink channel including a sidelink signal mapped to a specific resource in the corresponding sidelink channel. The sidelink communication can support broadcast services, multicast services, groupcast services, and unicast services.

[0119] The base station can send system information (e.g., SIB12, SIB13, SIB14) and RRC messages including configuration information for sidelink communication (i.e., sidelink configuration information) to the UE. The UE can receive the system information and RRC messages from the base station, identify the sidelink configuration information included in the system information and RRC messages, and perform sidelink communication based on the sidelink configuration message. SIB12 can include sidelink communication / discovery configuration information. SIB13 and SIB14 can include configuration information for V2X sidelink communication.

[0120] Sidelink communication can be performed within a SL bandwidth part (BWP). The base station can configure the SL BWP for the UE using higher layer signaling. The higher layer signaling can include SL-BWP-Config and / or SL-BWP-ConfigCommon. SL-BWP-Config can be used to configure the SL BWP for UE-specific sidelink communication. SL-BWP-ConfigCommon can be used to configure cell-specific configuration information.

[0121] In addition, the base station can configure a resource pool for the UE using higher layer signaling. The higher layer signaling can include SL-BWP-PoolConfig, SL-BWP-PoolConfigCommon, SL-BWP-DiscPoolConfig, and / or SL-BWP-DiscPoolConfigCommon. SL-BWP-PoolConfig can be used to configure a sidelink communication resource pool. SL-BWP-PoolConfigCommon can be used to configure a cell-specific sidelink communication resource pool. SL-BWP-DiscPoolConfig can be used to configure a resource pool dedicated to UE-specific sidelink discovery. SL-BWP-DiscPoolConfigCommon can be used to configure a resource pool dedicated to cell-specific sidelink discovery. The UE can perform sidelink communication within the resource pool configured by the base station.

[0122] Sidelink communication can support SL discontinuous reception (DRX) operation. The base station can send a higher layer message (e.g., SL-DRX-Config) including parameters related to SL DRX to the UE. The UE can perform SL DRX operation based on the SL-DRX-Config received from the base station. Sidelink communication can support inter-UE coordination operation. The base station can send a higher layer message (e.g., SL-InterUE-CoordinationConfig) including inter-UE coordination parameters to the UE. The UE can perform inter-UE coordination operation based on the SL-InterUE-CoordinationConfig received from the base station.

[0123] Sidelink communication can be performed based on a single SCI scheme or a multi-SCI scheme. When using the single SCI scheme, data transmission (e.g., sidelink data transmission, sidelink shared channel (SL-SCH) transmission) can be performed based on one SCI (e.g., the first-stage SCI (1 st -stage SCI)). When using the multi-SCI scheme, two SCIs (e.g., the first-stage SCI and the second-stage SCI (2 nd-stage SCI)) to perform data transmission. The SCI can be transmitted on the PSCCH and / or PSSCH. When using the single-SCI scheme, the SCI (e.g., the first-stage SCI) can be transmitted on the PSCCH. When using the multi-SCI scheme, the first-stage SCI can be transmitted on the PSCCH, and the second-stage SCI can be transmitted on the PSCCH or PSSCH. The first-stage SCI can be referred to as the "first-stage SCI (first-stage SCI)", and the second-stage SCI can be referred to as the "second-stage SCI (second-stage SCI)". The format of the first-stage SCI can include SCI format 1-A, and the format of the second-stage SCI can include SCI format 2-A, SCI format 2-B, and SCI format 2-C.

[0124] SCI format 1-A can be used to schedule the PSSCH and the second-stage SCI. SCI format 1-A can include at least one of priority information, frequency resource allocation information, time resource allocation information, resource reservation period information, demodulation reference signal (DMRS) mode information, second-stage SCI format information, beta-offset indicator, number of DMRS ports, modulation and coding scheme (MCS) information, additional MCS table indicator, PSFCH overhead indicator, or conflict information receiver flag.

[0125] SCI format 2-A can be used for decoding the PSSCH. SCI format 2-A can include at least one of the number of HARQ processors, new data indicator (NDI), redundancy version (RV), source ID, destination ID, HARQ feedback enable / disable indicator, cast type indicator, or CSI request.

[0126] SCI format 2-B can be used for the decoding of PSSCH. SCI format 2-B can include at least one of the number of HARQ processors, NDI, RV, source ID, destination ID, HARQ feedback enable / disable indicator, zone ID, or communication range requirement.

[0127] SCI format 2-C can be used for the decoding of PSSCH. In addition, SCI format 2-C can be used to provide or request inter-UE coordination information. SCI format 2-C can include at least one of the number of HARQ processors, NDI, RV, source ID, destination ID, HARQ feedback enable / disable indicator, CSI request, or provide / request indicator.

[0128] When the value of the provide / request indicator is set to 0, this can indicate that SCI format 2-C is used to provide inter-UE coordination information. In this case, SCI format 2-C can include at least one of resource combination, first resource location, reference time slot location, resource set type, or lowest sub-channel index.

[0129] When the value of the provide / request indicator is set to 1, this can indicate that SCI format 2-C is used to request inter-UE coordination information. In this case, SCI format 2-C can include at least one of priority, number of sub-channels, resource reservation period, resource selection window location, resource set type, or padding bit.

[0130] On the other hand, sidelink communication can be performed in an authorized band and / or an unauthorized band. The sidelink communication performed in the unauthorized band can be referred to as sidelink-unlicensed band (SL-U) communication or unlicensed band-sidelink (U-SL) communication. In SL-U communication, the first terminal can communicate with the second terminal according to mode 1 or mode 2. When using mode 1, the first terminal can communicate with the second terminal based on the scheduling of the base station. When using mode 2, the first terminal can communicate with the second terminal without the scheduling of the base station. Mode 1 can correspond to sidelink TM#1 or TM#3 disclosed in Table 2 above. Mode 2 can correspond to sidelink TM#2 or TM#4 disclosed in Table 2 above.

[0131] Figure 9 is a timing diagram showing a first exemplary embodiment of a communication method in an unauthorized band.

[0132] As Figure 9As shown, the base station may perform listen before talk (LBT) operations to perform downlink (DL) transmissions. If the result of the LBT operation indicates that the channel is in an idle state (e.g., a clean state), the base station may perform DL transmissions. The terminal may perform LBT operations to perform uplink (UL) transmissions. If the result of the LBT operation indicates that the channel is in an idle state, the terminal may perform UL transmissions. If the result of the LBT operation indicates that the channel is in a busy state, DL transmissions and / or UL transmissions may not be performed. DL transmissions and / or UL transmissions may be performed within the channel occupancy time (COT). The COT may be enabled by the base station or the terminal. The LBT operation may be performed based on one of the categories disclosed in Table 3 below.

[0133] [Table 3]

[0134]

[0135] The LBT operation may refer to a clear channel assessment (CCA) operation. The CCA operation may be performed during a CCA period. When performing the CCA operation, a communication node (e.g., a base station and / or a terminal) may identify the channel state based on an energy detection (ED) scheme. In other words, the communication node may determine whether there is another signal in the channel. If the energy detected during the CCA period is less than a threshold (e.g., an ED threshold), the communication node may determine that the channel state is an idle state. In other words, the communication node may determine that there is no other signal in the channel. If the channel state is determined to be an idle state, the communication node may access the channel within the COT. If the energy detected during the CCA period is equal to or higher than the threshold, the communication node may determine that the channel state is a busy state. In other words, the communication node may determine that there is another signal in the channel. If the channel state is a busy state, the communication node may not be able to access the channel within the COT.

[0136] In an unlicensed band, a communication node can perform a LBT operation and transmit data when the result of the LBT operation indicates an idle state of the channel. In this case, the base station can transmit a DL transmission burst within a COT, and the terminal can transmit a UL transmission burst within a COT. The COT can be configured within a maximum COT (MCOT). The slot duration of the CCA can be 5 μs to 9 μs. The duration of the MCOT can be 8 ms. The base station can initiate and / or configure a COT based on the higher layer parameter SemiStaticChannelAccessConfig. SemiStaticChannelAccessConfig can include information about the period of the COT. The terminal can identify the COT initiated by the base station based on SemiStaticChannelAccessConfig.

[0137] The terminal can initiate and / or configure a COT based on the higher layer parameter SemiStaticChannelAccessConfigUE. SemiStaticChannelAccessConfigUE can include information about the period and offset of the COT. The terminal can identify the COT initiated by the terminal based on SemiStaticChannelAccessConfigUE.

[0138] The terminal can initiate and / or configure a COT based on SemiStaticChannelAccessConfigUE in the unlicensed band. As another method, the base station can signal the terminal SemiStaticChannelAccessConfigSL-U of the COT for SL-U communication. The COT for SL-U communication can be referred to as a sidelink (SL)-COT. SemiStaticChannelAccessConfigSL-U can include information about the period and offset of the SL-COT. The terminal can configure the SL-COT based on SemiStaticChannelAccessConfig-U. Other terminals can identify the COT initiated based on SemiStaticChannelAccessConfigSL-U.

[0139] In the unlicensed band, the terminal can perform a LBT operation before SL communication (e.g., transmission of SL data) in order to perform SL communication. If the LBT operation is successful, a COT can be initiated in the unlicensed band, and SL communication can be performed within the COT. "The LBT operation is successful" can mean that the result of the LBT operation indicates an idle state.

[0140] In an unlicensed band, the channel access process can be classified into a DL channel access process and a UL channel access process. The DL channel access process can be classified into a type 1 DL channel access process and a type 2 DL channel access process. The type 1 DL channel access process can be executed for the initiation of a COT. The type 2 DL channel access process can be executed for transmission within a COT (e.g., a shared COT). The channel access process may refer to LBT operation. The type 1 DL channel access process can be executed for at least one of a physical downlink shared channel (PDSCH) transmission, a physical downlink control channel (PDCCH) transmission, or an enhanced PDCCH (EPDCCH) transmission initiated by an eNB and / or any transmission initiated by a gNB. An eNB may refer to a base station in a 4G communication system, and a gNB may refer to a base station in a 5G communication system.

[0141] The type 2 DL channel access process can be executed for at least one of a discovery burst transmission initiated by an eNB or a transmission excluding PDSCH and / or a discovery burst transmission multiplexed with non - unicast information or a discovery transmission initiated by a gNB. The type 2 DL channel access process can be classified into a type 2A DL channel access process, a type 2B DL channel access process, and a type 2C DL channel access process. The length of the sensing period (e.g., sensing interval) in the type 2A DL channel access process, the type 2B DL channel access process, and the type 2C DL channel access process may be different. The length of the sensing period in the type 2A DL channel access process can be 25 μs. The length of the sensing period in the type 2B DL channel access process can be 16 μs. No sensing operation may be performed in the type 2C DL channel access process.

[0142] The UL channel access procedure can be classified into a type 1 UL channel access procedure and a type 2 UL channel access procedure. The type 1 UL channel access procedure can be executed for the initiation of COT. The type 2 UL channel access procedure can be executed for transmissions within a COT (e.g., a shared COT). The type 1 UL channel access procedure can be executed for at least one of the physical uplink shared channel (PUSCH) transmissions or sounding reference signal (SRS) transmissions scheduled or configured by the eNB, at least one of the PUSCH transmissions or SRS transmissions scheduled or configured by the gNB, the PUCCH transmissions scheduled or configured by the gNB, and / or the transmissions related to the random access (RA) procedure.

[0143] The type 2 UL channel access procedure can be classified into a type 2A UL channel access procedure, a type 2B UL channel access procedure, and a type 2C UL channel access procedure. The lengths of the sensing periods for the type 2A UL channel access procedure and the type 2B UL channel access procedure can be different. The length of the sensing period in the type 2A UL channel access procedure can be 25 μs. The length of the sensing period in the type 2B UL channel access procedure can be 16 μs. No sensing operation may be performed in the type 2C UL channel access procedure.

[0144] The type 1 DL channel access procedure, the type 2 DL channel access procedure, the type 1 UL channel access procedure, and / or the type 2 UL channel access procedure can be used for SL-U communication. In this case, in the descriptions of the type 1 DL channel access procedure, the type 2 DL channel access procedure, the type 1 UL channel access procedure, and / or the type 2 UL channel access procedure, the downlink channel and / or the uplink channel can be interpreted as the sidelink channel. The LBT operation can be interpreted as the type 1 DL channel access procedure, the type 2 DL channel access procedure, the new type DL channel access procedure, the type 1 UL channel access procedure, the type 2 UL channel access procedure, and / or the new type UL channel access procedure.

[0145] In SL-U communication, a communication node (e.g., a base station, a terminal) can perform the LBT operation before transmission. For the sending and receiving of SL data, an automatic gain control (AGC) operation may be required. The first symbol of slot N can be used for the AGC operation. Therefore, the LBT operation can be performed before the start of the AGC operation in SL-U communication. The symbol used for the AGC operation can be referred to as the AGC symbol. The communication node can perform the transmission (e.g., data transmission) after performing the LBT operation and the AGC operation.

[0146] Figure 10 It is a conceptual diagram showing a first exemplary embodiment of the LBT operation in SL-U communication.

[0147] As Figure 10 shown, the LBT operation can be performed before the start of the AGC operation. The LBT operation can be performed in the last symbol (e.g., the guard symbol) of time slot N-1, or in the last symbol of time slot N-1 and the first symbol of time slot N (e.g., the AGC symbol). The communication node can perform transmission (e.g., data transmission) after performing the LBT operation and the AGC operation. In an exemplary embodiment of the present invention, it can be assumed that the LBT operation is performed in the manner Figure 10 shown. Alternatively, it can also be assumed that the LBT operation is performed in a manner other than the manner Figure 10 shown.

[0148] When the subcarrier spacing (SCS) is 15 kHz, considering the CCA time slot duration, the LBT period can be configured within a single symbol. The LBT period can be the period during which the LBT operation is performed. The length of one time slot can be 71.4 μs. When different SCSs are used, the same or a similar method can be applied. When the SCS is larger, the LBT period can be configured within two or more symbols to ensure the CCA time slot duration.

[0149] In Figure 10 the exemplary embodiment, when the LBT operation for SL communication fails in time slot N, the terminal may not perform SL communication (e.g., SL transmission) in time slot N. In this case, the terminal can perform the LBT operation in the last symbol of time slot N and / or the AGC symbol of the next time slot N+1 of time slot N, and when the LBT operation is successful, the terminal can perform SL communication in time slot N+1. The last symbol of time slot N in which the LBT operation is performed and / or the AGC symbol of the next time slot of time slot N can be the LBT period. When the LBT operation fails in the LBT period for SL communication in time slot N, the terminal may not perform SL communication until the LBT operation is successful in the next LBT period (e.g., the LBT period for SL communication in time slot N+1). In this case, the SL communication may experience a delay of one time slot.

[0150] To prevent delays in SL communication, one or more start positions for performing the LBT operation can be configured within a time slot. The start position can refer to a starting point. The terminal can perform the LBT operation at each of the one or more start positions within the time slot. For example, the terminal can perform the LBT operation at the first start position (e.g., the first start symbol corresponding to the first start position) within the time slot. When the LBT operation fails at the first start position, the terminal can perform the LBT operation at the second start position (e.g., the second start symbol corresponding to the second start position) within the time slot. When the LBT operation is successful, the terminal can perform the AGC operation and then perform SL communication. When multiple start positions (e.g., multiple start symbols) are configured within a time slot, the AGC operation can be performed not only at the first symbol within the time slot but also at other symbols. The number of other symbols at which the AGC operation is performed within the time slot can be one or more.

[0151] Multiple start positions can be configured within one time slot. The first symbol within the time slot can be a start position, and one or more symbols after the first symbol within the time slot can be configured as start positions. When there are two start positions within one time slot, the first symbol within the time slot can be a start position, and the remaining start position (e.g., the additional start position) within one time slot can be configured as a certain symbol after the first symbol. A certain symbol configured as the additional start position within one time slot can be as follows. The additional start position can refer to an additional start symbol.

[0152] - One of the second symbol to the thirteenth symbol within the time slot can be configured as an additional start position for the LBT operation.

[0153] - The nth symbol within the time slot can be configured as an additional start position for the LBT operation. n can be a natural number equal to or greater than 2.

[0154] - The symbol before m symbols of the PSSCH symbol (e.g., the starting PSSCH symbol) within the time slot can be configured as an additional start position for the LBT operation. The PSSCH symbol can refer to the symbol for performing PSSCH transmission. m can be a natural number.

[0155] - The symbol after 1 symbol of the PSCCH transmission (e.g., the ending PSCCH symbol) within the time slot can be configured as an additional start position for the LBT operation. The PSCCH symbol can refer to the symbol for performing PSCCH transmission. 1 can be a natural number.

[0156] - The PSSCH DMRS symbol within the time slot can be configured as an additional start position for the LBT operation. The PSSCH DMRS symbol can refer to the symbol for transmitting the DMRS for demodulation and / or decoding of the PSSCH.

[0157] When the additional start position within a time slot is configurable at any symbol after the first symbol, the receiving terminal can perform AGC operations in each symbol to receive the SL channel / signal from the transmitting terminal, and the receiving terminal can perform blind decoding operations for PSCCH detection one or two symbols after the end time of the AGC operation (e.g., the AGC symbol). In this case, the load and / or complexity of the receiving terminal may increase. Therefore, in SL-U communication, it may be preferable to dynamically indicate the additional start position to the terminal. As another method, in SL-U communication, the additional start position may preferably be preconfigured for the terminal. For example, the additional start position may be preconfigured for the terminal based on the PSSCH DMRS symbol.

[0158] The position of the PSSCH DMRS in the time domain (e.g., the PSSCH DMRS symbol) can be defined as shown in Table 4. Referring to Table 4, the length l of the scheduled resource d can mean the number of scheduled symbols. In other words, the length l of the scheduled resource d can mean the number of symbols of the PSSCH (e.g., the PSSCH duration) included in the time domain. The minimum number of symbols required for SL data transmission can be six symbols. The six symbols can include at least the AGC symbol. In other words, the PSSCH (e.g., the PSSCH duration) can include at least the AGC symbol (e.g., the first symbol of the time slot). The additional start position (e.g., the additional start point) within the time slot can be configured based on the PSSCH DMRS symbol.

[0159] [Table 4]

[0160]

[0161]

[0162] [Method 1: The additional start position can be configured in a symbol other than the PSSCH DMRS symbol]

[0163] When four PSSCH DMRS symbols are configured within a time slot, the additional start position can be configured as a symbol before and / or after the second PSSCH DMRS symbol. As another method, when four PSSCH DMRS symbols are configured within a time slot, the additional start position can be configured as a symbol before and / or after the third PSSCH DMRS symbol.

[0164] When four PSSCH DMRS symbols are configured within a time slot and an additional start position is configured based on the first PSSCH DMRS symbol, the time interval between the start positions (e.g., the first start position and the additional start position) can be short. When the time interval between the start positions is short, if the LBT operation fails at the first start position, the terminal may not be able to perform the LBT operation at the second start position (e.g., the additional start position). In this case, the SL communication may experience a delay of one time slot.

[0165] When four PSSCH DMRS symbols are configured within a time slot and an additional start position is configured based on the last PSSCH DMRS symbol, the length of the period from the additional start position to the end time of the time slot can be short. In this case, after the LBT operation succeeds at the additional start position, the resources and / or processing time for PSCCH / PSSCH transmission may be insufficient. PSCCH / PSSCH transmission can refer to PSCCH transmission and / or PSSCH transmission.

[0166] Considering the above problems, it may be preferable to configure the additional start position based on the remaining PSSCH DMRS symbols other than the first PSSCH DMRS symbol and the last PSSCH DMRS symbol. When four PSSCH DMRS symbols are configured within a time slot, the remaining PSSCH DMRS symbols used as a reference for configuring the additional start position can be the second PSSCH DMRS symbol and / or the third PSSCH DMRS symbol. The additional start position can be configured as the symbol before and / or after the second PSSCH DMRS symbol and / or the symbol before and / or after the third PSSCH DMRS symbol.

[0167] When three PSSCH DMRS symbols are configured within a time slot and an additional start position is configured based on the first PSSCH DMRS symbol, the time interval between the start positions (e.g., the first start position and the additional start position) can be short. When the time interval between the start positions is short, if the LBT operation fails at the first start position, the terminal may not be able to perform the LBT operation at the second start position (e.g., the additional start position). In this case, the SL communication may experience a delay of one time slot.

[0168] When three PSSCH DMRS symbols are configured within a time slot and an additional start position is configured based on the last PSSCH DMRS symbol, the length of the period from the additional start position to the end time of the time slot can be short. In this case, after the LBT operation succeeds at the additional start position, the resources and / or processing time for PSCCH / PSSCH transmission may be insufficient.

[0169] In view of the above problems, preferably, an additional start position is configured based on the remaining PSSCH DMRS symbols in the PSSCH DMRS symbols except for the first PSSCH DMRS symbol and the last PSSCH DMDS symbol. When three PSSCH DMRS symbols are configured within a time slot, the remaining PSSCH DMRS symbol used as the basis for configuring the additional start position may be the second PSSCH DMRS symbol. The additional start position may be configured as a symbol before and / or after the second PSSCH DMRS symbol.

[0170] When two PSSCH DMRS symbols are configured within a time slot, the PSSCH DMRS symbols may be located in the front or rear symbols within the PSSCH duration. In this case, it may be difficult to configure an additional start position. Therefore, when two PSSCH DMRS symbols are configured within a time slot, only one start position may be configured, and one start position may be the first symbol within the time slot or a symbol after the first symbol.

[0171] In view of the above situation, it is preferably to configure three or four PSSCH DMRS symbols in SL-U communication. The base station may send a sl-PSSCH-DMRS-TimePatternList indicating the configuration of three or four PSSCH DMRS symbols to the terminal. The terminal may determine to configure three or four PSSCH DMRS symbols within a time slot based on the sl-PSSCH-DMRS-TimePatternList received from the base station. The base station may send the information element defined in Table 5 to the terminal by signaling. The terminal may determine the additional start position (e.g., additional start point) based on the information element received from the base station. Alternatively, the transmitting terminal may send the information element defined in Table 5 to the receiving terminal by signaling. The receiving terminal may determine the additional start position (e.g., start point) based on the information element received from the transmitting terminal.

[0172] [Table 5]

[0173]

[0174] The information elements defined in Table 5 can be configuration information for a start position (e.g., an additional start position). The start position can be configured for each SL bandwidth part (BWP). For example, the start position in the first BWP can be configured independently of the start position in the second SL BWP. The information elements defined in Table 5 can be transmitted by different communication nodes (e.g., a base station and a terminal). For example, the base station can send a signaling message including information elements #2, #3, #4, #5, #6, #7, and / or #8 to the terminal, and the sending terminal can send a signaling message including information element #1 to the receiving terminal. The information elements defined in Table 5 can be transmitted by different signaling messages (e.g., RRC signaling messages, MAC signaling messages, PHY signaling messages). For example, the first communication node can send an RRC signaling message including information elements #2, #3, #4, #5, #6, #7, and / or #8 to the second communication node, and the first communication node can send a MAC signaling message or a PHY signaling message including information element #1 to the second communication node.

[0175] The sending terminal can determine the additional start position based on the information elements defined in Table 5. If the LBT operation is successful at the first start position within a time slot and SL communication (e.g., PSCCH / PSSCH transmission) is performed based on the successful execution of the LBT operation, the sending terminal may not perform the LBT operation at the additional start position. If the LBT operation fails at the first start position within a time slot, the sending terminal can perform the LBT operation at the additional start position, and if the LBT operation is successful, SL communication can be performed.

[0176] The receiving terminal can identify the additional start position based on the information elements defined in Table 5. The receiving terminal can perform a monitoring operation (e.g., a blind decoding operation) based on the LBT operation at the first start position within a time slot to receive an SL transmission (e.g., a PSCCH / PSSCH transmission). If the SL transmission based on the LBT operation at the first start position within a time slot is successfully received, the receiving terminal may not perform the monitoring operation to receive the SL transmission based on the LBT operation at the additional start position within the time slot. If the reception of the SL transmission based on the LBT operation at the first start position within a time slot fails, the receiving terminal can perform the monitoring operation to receive the SL transmission based on the LBT operation at the additional start position within the time slot. If the reception of the SL transmission based on the LBT operation at all additional start positions within a time slot fails, the receiving terminal may not expect to receive an SL transmission from the sending terminal within the time slot. In other words, the SL transmission of the sending terminal may experience a delay of one time slot.

[0177] To reduce the load and / or complexity of the blind decoding operation of the PSCCH at the receiving terminal, the additional start position can be fixed to a specific symbol. When three PSSCH DMRS symbols are configured within a time slot, the additional start position can be fixed to the symbol before and / or after the second PSSCH DMRS symbol. When four PSSCH DMRS symbols are configured within a time slot, the additional start position can be fixed to the symbol before and / or after the second PSSCH DMRS symbol and / or the symbol before and / or after the third PSSCH DMRS symbol.

[0178] As another method, regardless of the number of PSSCH DMRS symbols configured within a time slot, the additional start position can be fixed to a symbol other than the PSSCH DMRS symbols within the time slot. In this case, the symbol configured with the additional start position can be defined as follows.

[0179] - The additional start position can be configured as the symbol after the PSCCH (e.g., the first-stage SCI, the last PSCCH symbol). If the symbol after the PSCCH is a PSSCH DMRS symbol, the additional start position can be configured as the symbol after the PSSCH DMRS symbol.

[0180] - The additional start position can be configured as the fourth symbol within the time slot. When three or four PSSCH DMRS symbols are configured within a time slot, the fifth symbol within the time slot can be a PSSCH DMRS symbol. Accordingly, the fourth symbol, which is the symbol before the fifth symbol, can be configured as the additional start position.

[0181] - The additional start position can be configured as the sixth symbol within the time slot. When three or four PSSCH DMRS symbols are configured within a time slot, the fifth symbol within the time slot can be a PSSCH DMRS symbol. Accordingly, the sixth symbol, which is the symbol after the fifth symbol, can be configured as the additional start position.

[0182] - The additional start position can be configured as the seventh symbol within the time slot. When three or four PSSCH DMRS symbols are configured within a time slot, the eighth symbol within the time slot can be a PSSCH DMRS symbol. Accordingly, the seventh symbol, which is the symbol before the eighth symbol, can be configured as the additional start position.

[0183] - The additional start position can be configured as the ninth symbol within the time slot. When three or four PSSCH DMRS symbols are configured within a time slot, the eighth symbol within the time slot can be a PSSCH DMRS symbol. Accordingly, the ninth symbol, which is the symbol after the eighth symbol, can be configured as the additional start position.

[0184] As another method, the additional start position can be configured as the symbol before and / or after the PSSCH DMRS symbol offset. The symbol offset can be configured for the terminal by signaling.

[0185] [Method 2: The additional start position can be configured in the PSSCH DMRS symbol]

[0186] When four PSSCH DMRS symbols are configured within a time slot, the additional start position can be configured as the second PSSCH DMRS symbol and / or the third PSSCH DMRS symbol.

[0187] When four PSSCH DMRS symbols are configured within a time slot and the additional start position is configured as the first PSSCH DMRS symbol, the time interval between the start positions (e.g., the first start position and the additional start position) can be short. If the time interval between the start positions is short, when the LBT operation fails in the first start position, the terminal may not be able to perform the LBT operation in the second start position (e.g., the additional start position). In this case, the SL communication may experience a delay of one time slot.

[0188] When four PSSCH DMRS symbols are configured within a time slot and the additional start position is configured as the last PSSCH DMRS symbol, the period from the additional start position to the end time of the time slot can be short. In this case, after the LBT operation succeeds in the additional start position, the resources and / or processing time for PSCCH / PSSCH transmission may be insufficient.

[0189] Considering the above problems, it may be preferable to configure the additional start position as the remaining PSSCH DMRS symbols other than the first PSSCH DMRS symbol and the last PSSCH DMRS symbol in the PSSCH DMRS symbol. When four PSSCH DMRS symbols are configured within a time slot, the remaining PSSCH DMRS symbols used as the basis for configuring the additional start position can be the second PSSCH DMRS symbol and / or the third PSSCH DMRS symbol. The additional start position can be configured as the second PSSCH DMRS symbol and / or the third PSSCH DMRS symbol.

[0190] When three PSSCH DMRS symbols are configured within a time slot and the additional start position is configured as the first PSSCH DMRS symbol, the time interval between the start positions (e.g., the first start position and the additional start position) can be short. If the time interval between the start positions is short, when the LBT operation fails at the first start position, the terminal may not be able to perform the LBT operation at the second start position (e.g., the additional start position). In this case, the SL communication may experience a delay of one time slot.

[0191] When three PSSCH DMRS symbols are configured within a time slot and the additional start position is configured as the last PSSCH DMRS symbol, the period from the additional start position to the end time of the time slot can be short. In this case, after the LBT operation succeeds at the additional start position, the resources and / or processing time for PSCCH / PSSCH transmission may be insufficient.

[0192] Considering the above problems, it may be preferable to configure the additional start position as the remaining PSSCH DMRS symbol other than the first PSSCH DMRS symbol and the last PSSCH DMRS symbol among the PSSCH DMRS symbols. When three PSSCH DMRS symbols are configured within a time slot, the remaining PSSCH DMRS symbol used as the basis for configuring the additional start position can be the second PSSCH DMRS symbol. The additional start position can be configured as the second PSSCH DMRS symbol.

[0193] When two PSSCH DMRS symbols are configured within a time slot, the PSSCH DMRS symbols can be located at the front or rear symbol within the PSSCH duration. In this case, it may be difficult to configure the additional start position. Therefore, when two PSSCH DMRS symbols are configured within a time slot, only one start position can be configured, and the start position can be the first symbol within the time slot.

[0194] In view of the above, it is preferable to configure three or four PSSCH DMRS symbols in SL-U communication. The base station can send the sl-PSSCH-DMRS-TimePatternList indicating the configuration of three or four PSSCH DMRS symbols to the terminal. The terminal can determine to configure three or four PSSCH DMRS symbols within a time slot based on the sl-PSSCH-DMRS-TimePatternList received from the base station. The base station can send the information elements defined in Table 6 to the terminal by signaling. The terminal can identify the additional start position (e.g., additional start point) based on the information elements received from the base station. As another method, the transmitting terminal can send the information elements defined in Table 6 to the receiving terminal by signaling. The receiving terminal can identify the additional start position (e.g., start point) based on the information elements received from the transmitting terminal.

[0195] [Table 6]

[0196]

[0197]

[0198] The information elements defined in Table 6 can be configuration information for the start position (e.g., additional start position). The start position can be configured for each SL BWP. For example, the start position in the first SL BWP can be configured independently of the start position in the second SL BWP. The information elements defined in Table 6 can be transmitted by different communication nodes (e.g., base station and terminal). For example, the base station can send a signaling message including information elements #2, #3, #4, #5, and / or #6 to the terminal, and the transmitting terminal can send a signaling message including information element #1 to the receiving terminal. The information elements defined in Table 6 can be transmitted by different signaling messages (e.g., RRC signaling message, MAC signaling message, PHY signaling message). For example, the first communication node can send an RRC signaling message including information elements #2, #3, #4, #5, and / or #6 to the second communication node, and the first communication node can send a MAC signaling message or PHY signaling message including information element #1 to the second communication node.

[0199] The transmitting terminal can identify the additional start position based on the information elements defined in Table 6. If the LBT operation is successful at the first start position within a time slot and SL communication (e.g., PSCCH / PSSCH transmission) is performed based on the successful execution of the LBT operation, the transmitting terminal can not perform the LBT operation at the additional start position. If the LBT operation fails at the first start position within a time slot, the transmitting terminal can perform the LBT operation at the additional start position, and if the LBT operation is successful, SL communication can be performed.

[0200] The receiving terminal can identify the additional start position based on the information element defined in Table 6. The receiving terminal can perform a monitoring operation (e.g., blind decoding operation) based on the LBT operation at the first start position within the time slot to receive the SL transmission (e.g., PSCCH / PSSCH transmission). If the SL transmission based on the LBT operation at the first start position within the time slot is successfully received, the receiving terminal may not perform the monitoring operation for receiving the SL transmission based on the LBT operation at the additional start position within the time slot. If the reception of the SL transmission based on the LBT operation at the first start position within the time slot fails, the receiving terminal can perform the monitoring operation for receiving the SL transmission based on the LBT operation at the additional start position within the time slot. If the reception of the SL transmission based on the LBT operation at all additional start positions within the time slot fails, the receiving terminal may not expect to receive the SL transmission from the transmitting terminal within the time slot. In other words, the SL transmission of the transmitting terminal may be delayed to the next time slot.

[0201] To reduce the load and / or complexity of the blind decoding operation of the receiving terminal for the PSCCH, the additional start position can be fixed to a specific symbol. When three PSSCH DMRS symbols are configured within the time slot, the additional start position can be fixed to the second PSSCH DMRS symbol. When four PSSCH DMRS symbols are configured within the time slot, the additional start position can be fixed to the second PSSCH DMRS symbol and / or the third PSSCH DMRS symbol.

[0202] As another method, regardless of the number of PSSCH DMRS symbols configured within the time slot, the additional start position can be fixed to certain symbols within the time slot. In this case, certain symbols configured with the additional start position can be defined as follows.

[0203] - The additional start position can be configured as the PSSCH DMRS symbol after the PSCCH (e.g., the first-stage SCI, the last PSCCH symbol).

[0204] - The additional start position can be configured as the fifth symbol within the time slot. When three or four PSSCH DMRS symbols are configured within the time slot, the fifth symbol within the time slot can be a PSSCH DMRS symbol. Accordingly, the fifth symbol can be configured as the additional start position.

[0205] - The additional start position can be configured as the eighth symbol within the time slot. When three or four PSSCH DMRS symbols are configured within the time slot, the eighth symbol within the time slot can be a PSSCH DMRS symbol. Accordingly, the eighth symbol can be configured as the additional start position.

[0206] On the other hand, for the AGC operation at the receiving terminal, the transmitting terminal may transmit a copy of the data (e.g., information, signal) to be transmitted in the next symbol after the symbol (e.g., the additional start symbol) configured as the additional start position in the additional start symbol. If the additional start symbol (e.g., the symbol configured as the additional start position) is a PSSCH DMRS symbol, the transmitting terminal may transmit a copy of the data (e.g., information, signal) to be transmitted in the next symbol after the additional start symbol in the additional start symbol. In this case, a copy of the data to be transmitted in the next symbol may be transmitted in the frequency resources of the additional start symbol (excluding one or more frequency resources to which the PSSCH DMRS is mapped according to the integration type). In this case, the PSSCH DMRS and the data (e.g., a part of the data) to be transmitted in the next symbol may be transmitted in the additional start symbol. According to the above operations, the AGC performance at the receiving terminal can be improved.

[0207] In SL-U communication, multiple start positions (e.g., multiple start symbols) may be configured. Among the multiple start symbols, the first start symbol may be referred to as the initial start symbol, the default start symbol, or the first start symbol. The initial start symbol may be configured as the first symbol within a time slot. Alternatively, the initial start symbol may be configured as one of the first to eighth symbols within a time slot. The remaining start symbols other than the initial start symbol among the multiple start symbols may be referred to as additional start symbols. The additional start symbols may be referred to as the second start symbol, the third start symbol, and so on.

[0208] To perform the AGC operation in each start symbol, a copy of the data to be transmitted in the next symbol after the start symbol may be transmitted in the start symbol. In this case, the overlap problem between the AGC symbol (or the next symbol of the AGC symbol) and the PSSCH DMRS symbol may be considered. The AGC symbol may be a start symbol. When the duration for SL transmission within a time slot (e.g., a period including one or more symbols) is short, two or more start symbols may not be configured within the time slot. The number of PSSCH DMRS symbols within the time slot, the positions of the PSSCH DMRS symbols, and / or the number of symbols for SL communication may be configured by higher layer signaling.

[0209] The base station may send a signaling message to the terminal, and the signaling message includes sl-LengthSymbols indicating the number of symbols for SL communication within a time slot. The terminal may determine the number of symbols for SL communication based on the sl-LengthSymbols included in the signaling message received from the base station. The sl-LengthSymbols may indicate 7 symbols, 8 symbols, 9 symbols, 10 symbols, 11 symbols, 12 symbols, 13 symbols, or 14 symbols for SL communication.

[0210] Figure 11 It is a conceptual diagram showing a second exemplary embodiment of the LBT operation in SL-U communication.

[0211] As Figure 11 shown, in SL-U communication, the number and / or position of PSSCH DMRS symbols may be configured considering the number and / or position of start symbols. If two start symbols are configured within a time slot and the two start symbols are symbol #0 and symbol #4, then three PSSCH DMRS symbols may be configured, and the three PSSCH DMRS symbols may be symbol #2, symbol #7, and symbol #10. The start symbols may be AGC symbols. The first PSSCH DMRS symbol may be located between the start symbols, and the second and third PSSCH DMRS symbols may be located after an additional start symbol (e.g., symbol #4).

[0212] Two start symbols may be configured by the base station. For example, the base station may send the configuration information of the start symbols to the terminal by signaling. The terminal may identify the start symbols based on the configuration information received from the base station. In other words, the terminal may identify that symbol #0 and symbol #4 are configured as start symbols based on the configuration information.

[0213] The transmitting terminal may perform the LBT operation in symbol #0 (e.g., the initial start symbol), and if the LBT operation is successful, it may perform SL transmission. If the LBT operation fails in symbol #0, the transmitting terminal may perform the LBT operation in symbol #4 (e.g., the additional start symbol). If the LBT operation is successful in symbol #4, the transmitting terminal may perform SL transmission. If the LBT operation fails in symbol #4, the transmitting terminal may not perform SL transmission in the current time slot. In other words, the SL transmission may be delayed to the next time slot.

[0214] The receiving terminal can perform a monitoring operation for SL transmission based on the LBT operation in symbol #0. If the SL transmission based on the LBT operation in symbol #0 is successfully received, the receiving terminal may not perform the monitoring operation for the SL transmission based on the LBT operation in symbol #4. If the reception of the SL transmission based on the LBT operation in symbol #0 fails, the receiving terminal can perform the monitoring operation for the SL transmission based on the LBT operation in symbol #4.

[0215] Figure 12 It is a conceptual diagram showing a third exemplary embodiment of the LBT operation in SL-U communication.

[0216] As Figure 12 shown, in SL-U communication, the number and / or position of PSSCH DMRS symbols can be configured considering the number and / or position of start symbols. If two start symbols are configured within a time slot and the two start symbols are symbol #0 and symbol #7, two PSSCH DMRS symbols can be configured, and the two PSSCH DMRS symbols can be symbol #3 and symbol #10. The start symbol can be an AGC symbol. The first PSSCH DMRS symbol can be located between the start symbols, and the second PSSCH DMRS symbol can be located after an additional start symbol (e.g., symbol #7).

[0217] Two start symbols can be configured by the base station. For example, the base station can send the configuration information of the start symbols to the terminal through signaling. The terminal can identify the start symbols based on the configuration information received from the base station. In other words, the terminal can identify that symbol #0 and symbol #7 are configured as start symbols based on the configuration information.

[0218] The transmitting terminal can perform the LBT operation in symbol #0 (e.g., the initial start symbol), and if the LBT operation is successful, it can perform the SL transmission. If the LBT operation fails in symbol #0, the transmitting terminal can perform the LBT operation in symbol #7 (e.g., the additional start symbol). If the LBT operation is successful in symbol #7, the transmitting terminal can perform the SL transmission. If the LBT operation fails in symbol #7, the transmitting terminal may not perform the SL transmission in the current time slot. In other words, the SL transmission may be delayed to the next time slot.

[0219] The receiving terminal can perform a monitoring operation for SL transmission based on the LBT operation in symbol #0. If the SL transmission based on the LBT operation in symbol #0 is successfully received, the receiving terminal may not perform the monitoring operation for the SL transmission based on the LBT operation in symbol #7. If the reception of the SL transmission based on the LBT operation in symbol #0 fails, the receiving terminal can perform the monitoring operation for the SL transmission based on the LBT operation in symbol #7.

[0220] Figure 13 It is a conceptual diagram showing a fourth exemplary embodiment of the LBT operation in SL-U communication.

[0221] As Figure 13 shown, in SL-U communication, the number and / or position of PSSCH DMRS symbols can be configured by considering the number and / or position of start symbols. If two start symbols are configured within a time slot and the two start symbols are symbol #0 and symbol #7, then three PSSCH DMRS symbols can be configured, and the three PSSCH DMRS symbols can be symbol #2, symbol #5, and symbol #10. The start symbols can be AGC symbols. The first PSSCH DMRS symbol and the second PSSCH DMRS symbol can be located between the start symbols, and the third PSSCH DMRS symbol can be located after an additional start symbol (e.g., symbol #7).

[0222] Two start symbols can be configured by the base station. For example, the base station can send the configuration information of the start symbols to the terminal by signaling. The terminal can identify the start symbols based on the configuration information received from the base station. In other words, the terminal can identify that symbol #0 and symbol #7 are configured as start symbols based on the configuration information.

[0223] The transmitting terminal can perform the LBT operation in symbol #0 (e.g., the initial start symbol), and if the LBT operation is successful, it can perform the SL transmission. If the LBT operation fails in symbol #0, the transmitting terminal can perform the LBT operation in symbol #7 (e.g., the additional start symbol). If the LBT operation is successful in symbol #7, the transmitting terminal can perform the SL transmission. If the LBT operation fails in symbol #7, the transmitting terminal can not perform the SL transmission in the current time slot. In other words, the SL transmission may be delayed to the next time slot.

[0224] The receiving terminal can perform the monitoring operation for the SL transmission based on the LBT operation in symbol #0. If the SL transmission based on the LBT operation in symbol #0 is successfully received, the receiving terminal can not perform the monitoring operation for the SL transmission based on the LBT operation in symbol #7. If the reception of the SL transmission based on the LBT operation in symbol #0 fails, the receiving terminal can perform the monitoring operation for the SL transmission based on the LBT operation in symbol #7.

[0225] In SL-U communication, the LBT period can be configured in a time unit other than the symbol unit. The above exemplary embodiments can be applied in the same or similar manner to the LBT periods configured in different time units.

[0226] In the above SL-U communication, information (e.g., LBT symbols) regarding the operation, configuration, and / or application of the LBT period can be specifically, independently, or jointly configured based on at least one of a resource pool, service type, priority, whether to perform power saving operations, QoS parameters (e.g., reliability, latency), broadcast type, or terminal type (e.g., vehicle (V)-UE or pedestrian (P)-UE). The above configuration can be performed by the network and / or the base station. Alternatively, the above information can be implicitly determined based on predefined parameters.

[0227] In the above exemplary embodiments, whether to apply each method (e.g., each rule) can be configured based on at least one of a condition, a combination of conditions, a parameter, or a combination of parameters. Whether to apply each method can be configured by the network and / or the base station. Whether to apply each method can be configured specifically for a resource pool or a service. Alternatively, whether to apply each method can be configured through PC5-RRC signaling between terminals.

[0228] The operation of the method according to an exemplary embodiment of the present invention can be implemented as a computer-readable program or code in a computer-readable recording medium. The computer-readable recording medium can include all types of recording devices that store data readable by a computer system. In addition, the computer-readable recording medium can store and execute programs or codes, which can be distributed in computer systems connected through a network and read by a computer in a distributed manner.

[0229] The computer-readable recording medium can include hardware devices specifically configured to store and execute program instructions, such as ROM, RAM, or flash memory. The program instructions can include not only machine language code created by a compiler but also high-level language code executable by a computer using an interpreter.

[0230] Although some aspects of the present invention have been described in the context of a device, these aspects can indicate corresponding descriptions according to the method, and a block or a device can correspond to a step of the method or a feature of the step. Similarly, aspects described in the context of the method can be represented as features of the corresponding block or item or the corresponding device. Some or all steps of the method can be executed by (or using) a hardware device such as a microprocessor, a programmable computer, or an electronic circuit. In some embodiments, one or more of the most important steps of the method can be executed by such a device.

[0231] In some exemplary embodiments, a programmable logic device such as a field-programmable gate array can be used to execute some or all of the functions of the method described herein. In some exemplary embodiments, the field-programmable gate array can be operated with a microprocessor to execute one of the methods described herein. Generally, the method is preferably executed by a specific hardware device.

[0232] The description of the present invention is merely exemplary in nature, so variations that do not depart from the essence of the present invention are intended to be within the scope of the present invention. Such variations should not be regarded as departing from the spirit and scope of the present invention. Thus, those of ordinary skill in the art will understand that various changes in form and detail can be made without departing from the spirit and scope defined by the appended claims.

Claims

1. A method of a first user equipment (UE), comprising: receiving configuration information of start symbols from a base station; identifying a plurality of start symbols based on the configuration information; performing a first listen-before-talk (LBT) operation on a first start symbol among the plurality of start symbols in a first time slot; and performing a second LBT operation on a second start symbol among the plurality of start symbols in the first time slot based on a failure of the first LBT operation in the first start symbol, wherein each of the first LBT operation and the second LBT operation is performed for a sidelink (SL) transmission to a second UE, and the second start symbol is located after the first start symbol in the time domain.

2. The method according to claim 1, wherein, in the first time slot, the second start symbol is configured as a symbol other than a physical sidelink shared channel (PSSCH) demodulation reference signal (DMRS) symbol, and the PSSCH DMRS symbol is a symbol for transmitting DMRS for demodulation of the PSSCH.

3. The method according to claim 2, wherein, in the first time slot, the second start symbol is configured as a symbol before or after the PSSCH DMRS symbol.

4. The method according to claim 1, wherein, in the first time slot, the second start symbol is configured as the PSSCH DMRS symbol.

5. The method according to claim 1, wherein, in the first time slot, the PSSCH DMRS symbol is configured in consideration of at least one of the number or position of the plurality of start symbols.

6. The method according to claim 1, wherein, when the second LBT operation is successful, an SL transmission is performed in the first time slot, and when the second LBT operation fails, an SL transmission is performed in a second time slot after the first time slot.

7. The method according to claim 1, wherein, a copy of data to be transmitted in a next symbol of the second start symbol is transmitted in the second start symbol.

8. The method according to claim 1, wherein, the configuration information includes information indicating the position of the first start symbol and information indicating the position of the second start symbol.

9. The method according to claim 8, wherein, the information indicating the position of the second start symbol is a symbol offset between the first start symbol and the second start symbol.

10. The method according to claim 1, wherein, when the use of a plurality of start symbols is enabled, the second LBT operation is performed in the second start symbol, and when the use of a plurality of start symbols is disabled, the second LBT operation is not performed in the second start symbol.

11. A method of a second user equipment (UE), comprising: receiving configuration information of start symbols from a base station; identifying a plurality of start symbols based on the configuration information; performing a first monitoring operation for an SL transmission to a first UE according to a first listen-before-talk (LBT) operation on a first start symbol among the plurality of start symbols in a first time slot; and in response to a reception failure of the SL transmission according to the first LBT operation, performing a second monitoring operation for the SL transmission to the first UE according to a second LBT operation on a second start symbol among the plurality of start symbols in the first time slot, Among them, the second start symbol is located after the first start symbol in the time domain.

12. The method according to claim 11, wherein, In the first time slot, the second start symbol is configured as a symbol other than the physical sidelink shared channel (PSSCH) demodulation reference signal (DMRS) symbol, and the PSSCH DMRS symbol is the symbol for transmitting the DMRS for demodulating the PSSCH.

13. The method according to claim 12, wherein, In the first time slot, the second start symbol is configured as a symbol before or after the PSSCH DMRS symbol.

14. The method according to claim 11, wherein, In the first time slot, the second start symbol is configured as the PSSCH DMRS symbol.

15. The method according to claim 11, wherein, In the first time slot, the PSSCH DMRS symbol is configured by considering at least one of the number or position of multiple start symbols.

16. The method according to claim 11, wherein, When the reception of the SL transmission according to the second LBT operation fails, the second UE does not expect to receive the SL transmission in the first time slot, and the SL transmission is delayed to a second time slot after the first time slot.

17. The method according to claim 11, wherein, A copy of the data to be received in the next symbol of the second start symbol is received in the second start symbol.

18. The method according to claim 11, wherein, The configuration information includes information indicating the position of the first start symbol and information indicating the position of the second start symbol.

19. The method according to claim 18, wherein, The information indicating the position of the second start symbol is the symbol offset between the first start symbol and the second start symbol.

20. The method according to claim 11, wherein, When the use of multiple start symbols is enabled, the second LBT operation is performed in the second start symbol, and when the use of multiple start symbols is disabled, the second LBT operation is not performed in the second start symbol.

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