Method and apparatus for initial beam pairing during unicast link establishment in sidelink communication

Abstract

Provided are a method and an apparatus for initial beam pairing during unicast link establishment in sidelink communication. A transmission terminal according to one embodiment of the present specification transmits a direct link establishment request (DCR) message to a reception terminal and receives a direct link establishment accept (DCA) message from the reception terminal in response to the transmitted direct link establishment request message, wherein the direct link establishment request message is transmitted together with a reference signal (RS) for beam pairing, and at least one of the direct link establishment request message and the direct link establishment accept message is repeated within a specific period.

Description

Method and device for initial beam pairing during unicast link establishment in sidelink communication

[0001] This specification relates to 3GPP 5G sidelink communications.

[0002] Sidelink (SL) refers to a method of establishing a direct link between terminals, thereby performing direct communication between terminals without going through a base station.

[0003] V2X (vehicle-to-everything) refers to communication that exchanges information with other vehicles, pedestrians, infrastructure-based objects, etc. through sidelinks. In other words, V2X can be divided into four types: V2V (vehicle-to-vehicle), V2I (vehicle-to-infrastructure), V2N (vehicle-to-network), and V2P (vehicle-to-pedestrian). V2X communication can be provided through the PC5 interface and / or Uu interface.

[0004] As more and more communication devices demand ever-increasing communication traffic, the need for next-generation 5G systems, which offer enhanced wireless broadband communication capabilities over existing LTE systems, is growing. This next-generation 5G system, known as NewRAT, differentiates communication scenarios into Enhanced Mobile BroadBand (eMBB), Ultra-reliability and low-latency communication (URLLC), and Massive Machine-Type Communications (mMTC).

[0005] Here, eMBB is a next-generation mobile communication scenario with characteristics such as High Spectrum Efficiency, High User Experienced Data Rate, and High Peak Data Rate; URLLC is a next-generation mobile communication scenario with characteristics such as Ultra Reliable, Ultra Low Latency, and Ultra High Availability (e.g., V2X, Emergency Service, and Remote Control); and mMTC is a next-generation mobile communication scenario with characteristics such as Low Cost, Low Energy, Short Packet, and Massive Connectivity (e.g., IoT).

[0006] An object of the present specification is to provide a method and device for initial beam pairing during unicast link establishment between terminals for sidelink communication in a wireless communication system.

[0007] One embodiment of the present specification provides a method in which, in sidelink (SL) communication, a transmitting terminal transmits a direct link establishment request (DCR) message to a receiving terminal, and receives a direct link establishment accept (DCA) message from the receiving terminal in response to the transmitted direct link establishment request, wherein the direct link establishment request message is transmitted together with a reference signal (RS) for beam pairing, and at least one of the direct link establishment request message and the direct link establishment accept message is repeated within a specific cycle.

[0008] In addition, one embodiment of the present specification provides a method in which, in sidelink (SL) communication, a receiving terminal receives a direct link establishment request (DCR) message from a transmitting terminal, and transmits a direct link establishment accept (DCA) message to the transmitting terminal in response to the received direct link establishment request message, wherein the direct link establishment request message is received together with a reference signal (RS) for beam pairing, and at least one of the direct link establishment request message and the direct link establishment accept message is repeated within a specific cycle.

[0009] In addition, one embodiment of the present specification provides a transmitting terminal, in a sidelink (SL) communication, including a control unit and a memory unit storing instructions and being operably electrically connectable to the control unit, wherein the operations performed based on the instructions being executed by the control unit include: transmitting a direct link establishment request (DCR) message, and receiving a direct link establishment accept (DCA) message in response to the transmitted direct link establishment request message, wherein the direct link establishment request message is transmitted together with a reference signal (RS) for beam pairing, and wherein at least one of the direct link establishment request message and the direct link establishment accept message is repeated within a specific period.

[0010] In addition, one embodiment of the present specification provides a sidelink (SL) communication system including a control unit and a memory unit storing instructions and being operably electrically connectable to the control unit, wherein the operations performed based on the instructions being executed by the control unit include: receiving a direct link establishment request (DCR) message, and transmitting a direct link establishment accept (DCA) message in response to the received direct link establishment request message, wherein the direct link establishment request message is received together with a reference signal (RS) for beam pairing, and at least one of the direct link establishment request message and the direct link establishment accept message is repeated within a specific period.

[0011] Meanwhile, the transmitting terminal may receive beam reporting based on the transmitted reference signal from the receiving terminal. Furthermore, the transmitting terminal may transmit a beam pairing response to the receiving terminal, wherein the beam pairing response may be transmitted prior to receiving the direct link establishment acceptance message.

[0012] The above beam reporting can be received based on a first specific time offset.

[0013] The above direct link setup acceptance message may be transmitted based on a second specific time offset.

[0014] The above reference signal may be at least one of a sidelink-synchronization signal block (S-SSB), a sidelink channel state information-reference signal (CSI-RS), and a sidelink channel demodulation-reference signal (DM-RS).

[0015] The above reference signal may be transmitted to the receiving terminal repeatedly within the specific period together with the above direct link establishment request message.

[0016] This specification targets the 5G / 5G-advanced system defined by 3GPP, but the technology / concept proposed in this specification can be applied to mobile communication systems other than 5G, such as LTE or 6G to be defined in the future.

[0017] According to the disclosure of this specification, initial beam pairing and unicast link setup for sidelink communication in the 3GPP 5G FR2 (frequency range 2) band can be efficiently performed.

[0018] Figure 1 is a diagram illustrating an NR wireless communication system.

[0019] Figure 2 illustrates the structure of a radio frame used in NR.

[0020] Figure 3 illustrates the slot structure of an NR frame.

[0021] Figure 4 is an example showing an NG-RAN architecture supporting the PC5 interface.

[0022] Figures 5a and 5b illustrate a procedure for performing sidelink communication according to a sidelink resource allocation mode.

[0023] FIG. 6 is an example of signaling for performing initial beam pairing and unicast link establishment according to one embodiment of the present specification.

[0024] FIG. 7 illustrates an example of beam sweeping according to one embodiment of the present specification.

[0025] FIG. 8 illustrates an example of a sidelink slot configuration according to one embodiment of the present specification.

[0026] FIGS. 9A and 9B illustrate examples of transmitting a DCR message and a CSI-RS within a beam sweeping period according to one embodiment of the present specification.

[0027] FIGS. 10A and 10B are further examples of signaling for performing initial beam pairing and unicast link establishment according to one embodiment of the present disclosure.

[0028] FIG. 11 illustrates a wireless communication device according to one embodiment of the present specification.

[0029] Although this specification describes embodiments using LTE systems, LTE-A systems, and NR systems, these embodiments may be applied to any communication system falling within the above definitions.

[0030] Additionally, the name of the base station in this specification may be used as a comprehensive term including RRH (remote radio head), eNB, TP (transmission point), RP (reception point), relay, etc.

[0031] 3GPP-based communication standards define downlink physical channels corresponding to resource elements that carry information originating from higher layers, and downlink physical signals corresponding to resource elements that are used by the physical layer but do not carry information originating from higher layers. For example, the physical downlink shared channel (PDSCH), physical broadcast channel (PBCH), physical multicast channel (PMCH), physical control format indicator channel (PCFICH), physical downlink control channel (PDCCH), and physical hybrid ARQ indicator channel (PHICH) are defined as downlink physical channels, and reference signals and synchronization signals are defined as downlink physical signals. A reference signal (RS), also referred to as a pilot, is a signal with a predefined special waveform known to the gNB and the UE. For example, cell specific RS, UE-specific RS (UE-RS), positioning RS (PRS), and channel state information RS (CSI-RS) are defined as downlink reference signals. The 3GPP LTE / LTE-A standard defines uplink physical channels corresponding to resource elements carrying information originating from higher layers, and uplink physical signals corresponding to resource elements used by the physical layer but not carrying information originating from higher layers.For example, a physical uplink shared channel (PUSCH), a physical uplink control channel (PUCCH), and a physical random access channel (PRACH) are defined as uplink physical channels, and a demodulation reference signal (DMRS) for uplink control / data signals and a sounding reference signal (SRS) used for uplink channel measurement are defined.

[0032] In this specification, PDCCH (Physical Downlink Control CHannel) / PCFICH (Physical Control Format Indicator CHannel) / PHICH ((Physical Hybrid automatic retransmit request Indicator CHannel) / PDSCH (Physical Downlink Shared CHannel) mean a set of time-frequency resources or a set of resource elements that carry DCI (Downlink Control Information) / CFI (Control Format Indicator) / downlink ACK / NACK (ACKnowlegement / Negative ACK) / downlink data, respectively. In addition, PUCCH (Physical Uplink Control CHannel) / PUSCH (Physical Uplink Shared CHannel) / PRACH (Physical Random Access CHannel) mean a set of time-frequency resources or a set of resource elements that carry UCI (Uplink Control Information) / uplink data / random access signals, respectively.

[0033] Meanwhile, the NR frequency band can be defined by two types of frequency ranges (FR1, FR2). The numerical values ​​of the frequency ranges can be changed, and for example, the two types of frequency ranges (FR1, FR2) can be as shown in Table 1 below. For convenience of explanation, among the frequency ranges used in the NR system, FR1 can mean the “sub 6 GHz range”, and FR2 can mean the “above 6 GHz range” and can be called millimeter wave (mmW).

[0034] Frequency Range designationCorresponding frequency rangeSubcarrier SpacingFR1410MHz - 7125MHz15, 30, 60kHzFR224250MHz - 52600MHz60, 120, 240kHz

[0035] The numerical value of the frequency range of the NR system can be changed. For example, FR1 can include a band from 410 MHz to 7125 MHz, as shown in Table 1. That is, FR1 can include frequency bands above 6 GHz (or 5850, 5900, 5925 MHz, etc.). For example, the frequency bands above 6 GHz (or 5850, 5900, 5925 MHz, etc.) included within FR1 can include unlicensed bands. Unlicensed bands can be used for various purposes, such as for vehicle communications (e.g., autonomous driving).

[0036] Figure 1 is a diagram illustrating an NR wireless communication system.

[0037] Referring to FIG. 1, the NR wireless communication system can be divided into a 5G core network (5GC) and a next generation-radio access network (NG-RAN), and the NG-RAN can include a base station (gNB and / or ng-eNB) that provides user plane and control plane protocol termination to user equipment (UE). The gNB (next generation-Node B) provides NR user plane and control plane protocol termination to the UE, and the ng-eNB (next generation-evolved Node B) provides evolved-universal terrestrial radio access (E-UTRA) user plane and control plane protocol termination to the UE. The UE can be fixed or mobile, and may be referred to by other terms such as a mobile station (MS), a user terminal (UT), a subscriber station (SS), a mobile terminal (MT), or a wireless device. A base station (gNB and / or ng-eNB) may be a fixed station that communicates with a terminal (UE) and may be called by other terms such as base transceiver system (BTS), access point, etc.

[0038] Base stations (gNB and / or ng-eNB) can be connected to each other via Xn interfaces and can be connected to 5GC (5G core network) via NG interfaces. Specifically, base stations (gNB and / or ng-eNB) can be connected to AMF (access and mobility management function) via NG-C interfaces and can be connected to UPF (user plane function) via NG-U interfaces.

[0039] Figure 2 illustrates the structure of a radio frame used in NR.

[0040] In NR, uplink and downlink transmissions are structured as frames. A radio frame is 10ms long and is defined by two 5ms half-frames (HF). Each half-frame is defined by five 1ms subframes (SF). A subframe is divided into one or more slots, and the number of slots in a subframe depends on the subcarrier spacing (SCS). Each slot contains 12 or 14 OFDM(A) symbols, depending on the cyclic prefix (CP). When a regular CP is used, each slot contains 14 symbols. When an extended CP is used, each slot contains 12 symbols. Here, the symbols can include OFDM symbols (or CP-OFDM symbols), SC-FDMA symbols (or DFT-s-OFDM symbols).

[0041] Table 2 illustrates that when CP is normally used, the number of symbols per slot, the number of slots per frame, and the number of slots per subframe vary depending on the SCS.

[0042] SCS(15*2 u )N slot symb N frame,u slot N subframe,u slot 15 KHz(u =0)1410130 KHz(u=1)1420260 KHz(u=2)14404120 KHz(u=3)14808240 KHz(u=4)1416016

[0043] N slot symb : Number of symbols in the slot

[0044] N frame,u slot : Number of slots in the frame

[0045] ​​N subframe,u slot : Number of slots in a subframe

[0046] Table 3 illustrates that when extended CP is used, the number of symbols per slot, the number of slots per frame, and the number of slots per subframe vary depending on the SCS.

[0047] SCS (15*2 u )N slot symb N frame,u slot N subframe,u slot 60KHz (u=2)12404

[0048] In an NR system, OFDM(A) numerology (e.g., SCS, CP length, etc.) may be set differently between multiple cells that are merged into a single terminal. Accordingly, the (absolute time) interval of a time resource (e.g., SF, slot, or TTI) (conveniently referred to as TU (Time Unit)) consisting of the same number of symbols may be set differently between the merged cells.

[0049] Figure 3 illustrates the slot structure of an NR frame.

[0050] ​​A slot contains multiple symbols in the time domain. For example, a slot contains 14 symbols for a regular CP, but 12 symbols for an extended CP. A carrier contains multiple subcarriers in the frequency domain. A resource block (RB) is defined as multiple (e.g., 12) consecutive subcarriers in the frequency domain. A bandwidth part (BWP) is defined as multiple consecutive (P)RBs in the frequency domain, and can correspond to a single numerology (e.g., SCS, CP length, etc.). A carrier can contain up to N (e.g., 4) BWPs. Data communication is performed through activated BWPs, and only one BWP can be activated for a single terminal. Each element in the resource grid is referred to as a resource element (RE), to which one complex symbol can be mapped.

[0051] Figure 4 is an example showing an NG-RAN architecture supporting the PC5 interface.

[0052] Referring to Figure 4, the NG-RAN (next generation-radio access network) architecture supports the PC5 interface. Sidelink transmission and reception via the PC5 interface are supported when the UE is inside NG-RAN coverage and when the UE is outside NG-RAN coverage, regardless of the RRC (radio resource control) state the UE is in.

[0053] Support for V2X (Vehicle-to-Everything) services via the PC5 interface can be provided by NR sidelink communications and / or V2X sidelink communications. NR sidelink communications can also be used to support services other than V2X services.

[0054] NR sidelink communication can support one of the following transmission modes: unicast, groupcast, and broadcast. In the case of unicast sidelink communication, a terminal can perform one-to-one communication with another terminal, and in the case of groupcast sidelink communication, a terminal can perform sidelink communication with one or more terminals within the group to which it belongs.

[0055] Figures 5a and 5b illustrate a procedure for performing sidelink communication according to a sidelink resource allocation mode.

[0056] Figure 5a shows terminal operation related to NR resource allocation mode 1, and Figure 5b shows terminal operation related to NR resource allocation mode 2.

[0057] Referring to FIG. 5A, in NR resource allocation mode 1, a base station can schedule sidelink (SL) resources to be used by a terminal (UE) for sidelink (SL) transmission. For example, the base station can perform resource scheduling using a downlink control channel (DCI) transmitted to terminal 1 (UE1) via a physical downlink control channel (PDCCH), and UE1 can perform V2X or SL communication with terminal 2 (UE2) according to the resource scheduling. For example, UE1 can transmit sidelink control information (SCI) to UE2 via a physical sidelink control channel (PSCCH), and then transmit SL data based on the SCI to UE2 via a physical sidelink shared channel (PSSCH).

[0058] Referring to FIG. 5b, in NR resource allocation mode 2, a terminal can determine an SL transmission resource within the SL resources configured by the base station or within preset SL resources. For example, the configured SL resources or preset SL resources may be an SL resource pool (sidelink resource pool). For example, the terminal can autonomously select or schedule resources for SL transmission. That is, the terminal can perform SL communication by selecting resources within the configured resource pool. In addition, the terminal can perform sensing and resource (re)selection procedures to select resources within a selection window. For example, the sensing can be performed on a sub-channel basis. As illustrated in FIG. 5b, UE1, which has selected a resource within the resource pool, can transmit SCI to UE2 via PSCCH and then transmit data based on the SCI to UE2 via PSSCH.

[0059] Meanwhile, the technology for performing initial beam pairing and unicast link establishment for sidelink communication in the FR2 (frequency range 2) band is currently under development. This specification proposes a procedure and detailed technology for performing initial beam pairing together with unicast link establishment. In particular, the present invention proposes a reference signal (RS) and message used for transmitting beam information in performing the initial beam pairing operation, a resource allocation method and / or an operation method for transmitting the corresponding signal / data. In addition, the present invention proposes a method for enabling the timer operation related to the transmission of the direct link establishment request (DCR) message and the direct link establishment accept (DCA) message to be operated in a form that takes the initial beam pairing operation procedure into consideration.

[0060] 3GPP is discussing beam-related technologies for sidelink communications in the FR2 band, and Table 4 below shows part of the related agreement.

[0061] Agreement (#112)For sidelink beam management, RAN1 is to study> how transmit beam(s) training and / or receive beam(s) training is performed> whether and how spatial related information (e.g., TCI, QCL, beam ID, etc.) information could be identified> the relationship between PC5 unicast link establishment and sidelink initial beam pairing (e.g., whether initial beam pairing procedure starts before, during or after sidelink unicast link establishment procedure.))Agreement (#112b)RAN1 is to study> how transmit beam(s) training and / or receive beam(s) training is performed> whether and how spatial related information (e.g., TCI, QCL, beam ID, etc.) information could be identified> the relationship between PC5 unicast link establishment and sidelink initial beam pairing (e.g., whether initial beam pairing procedure starts before, during or after sidelink unicast link establishment procedure.)) The following candidate procedure can be studied: UE1 transmits PSCCH / PSSCH carrying unicast link establishment messages (e.g., DCR messages) through different transmission beams; Note: Multiple PSCCH / PSSCH transmissions from each beam (e.g.,>> FFS: Applicable reference signals transmitted with unicast link establishment message. >> If UE2 successfully decodes one (or more) of the PSCCH / PSSCH(s) and UE2 decides to establish a unicast link with UE1, then instruct UE1 to use the UE1 transmit beam of one (or more) of the successfully received PSCCH / PSSCH(s). >> FFS details (e.g., implicit or explicit indication). >> FFS: How to map each PSCCH / PSSCH to the UE1 transmit beam. >> FFS: How UE2 decides the UE1 transmit beam(s) and / or the UE2 transmit / receive beam(s). >> UE1 completes the remaining sidelink unicast link establishment procedure with UE2 using one of the indicated beam(s). >> FFS: How UE1 decides one of the indicated beam(s). >> FFS: Use of additional reference signals or additional messages or additional measurements for efficient beam pairing (Agreement) (#112b)RAN1 can study the following candidate procedure where initial beam pairing is performed during sidelink unicast link establishment> UE1 sends PSCCH / PSSCH that carries unicast link establishment message (eg, DCR message) via different transmit beams>> Note: multiple PSCCH / PSSCH transmissions (eg,repetitions) from each of the beams can be studied.>> FFS: applicable reference signals which are transmitted together with unicast link establishment message.> if UE2 successfully decodes one (or more) of the PSCCH / PSSCH(s) and UE2 determines to establish a unicast link with UE1, it indicates to UE1 one (or more) UE1 transmit beam(s) of PSCCH / PSSCH(s) which is successfully received>> FFS details (e.g., implicit or explicit indication)>> FFS: how to map between each PSCCH / PSSCH and UE1 transmit beam>> FFS: how UE2 determines UE1 transmit beam(s) and / or UE2 transmit / receive beam(s)> UE1 uses one of the indicated beam(s) to finish the remaining sidelink unicast link establishment procedure with UE2>> FFS: how UE1 determines one of the indicated beam(s)> FFS: use of additional reference signal or additional messages or additional measurement for efficient beam pairing.)합의 (#112b)UE1과 UE2 간의 초기 빔 페어링을 위해 S-SSB의 적용 가능성을 연구하기 위해 적어도 다음 사항을 고려할 수 있음.> UE2가 UE1의 S-SSB 전송으로부터 UE1(예로,Whether / how to enable UE2 to identify UE1 (e.g., source ID) from UE1's S-SSB transmission, to enable UE1 to identify the corresponding beam measurement / reporting from UE2> Mapping between S-SSB transmission / resources and beam-related information> Assignment of beam reporting resources associated with different S-SSB transmission beams> Structure and content of S-SSB> Triggering and / or activating S-SSB transmission, if necessary> S-SSB monitoring and reporting / response mechanism> Mechanism to mitigate / avoid interference between overlapped S-SSB transmissions from different UEs, including S-SSB transmission resources> Potential impacts on / from other UEs, and whether / how to avoid or mitigate such impacts (Agreement (#112b) To study the feasibility of adapting S-SSB for initial beam pairing between UE1 and UE2, at least the following can be considered.> Whether / how to enable UE2 to identify UE1 (e.g., source ID) from UE1's S-SSB transmission, to enable UE1 to identify the corresponding beam measurement / reporting from UE2> Mapping between S-SSB transmission / resource and beam related information> Allocation of beam reporting resources respectively associated with different S-SSB transmit beams> Structure and contents of S-SSB> Triggering and / or activation of S-SSB transmission,If needed> Mechanism for S-SSB monitoring and reporting / responding> Mechanism to mitigate / avoid the interference between overlapped S-SSB transmissions from different UEs, including S-SSB transmission resources> Potential impact to / from other UEs, and whether / how to avoid or mitigate this impact) Agreement (#112b) At least the following enhancements may be considered to study the feasibility of reusing SL CSI-RS for initial beam pairing:> SL CSI-RS transmission with or without sidelink data transmission in the same slot>> FFS: slot structure> Mapping between SL CSI-RS transmissions / resources and beam-related information> Periodic SL CSI-RS transmissions, semi-static SL CSI-RS transmissions, or aperiodic SL CSI-RS transmissions with or without SCI indication> Allocation of SL CSI-RS beam sweeping resources and, if applicable, associated beam reporting resources> Study the feasibility of applying SL CSI-RS for initial beam pairing before, during, or after unicast link establishment>> FFS: How to provide SL CSI-RS resource configuration> Whether or how to mitigate / avoid interference between overlapping SL CSI-RS transmissions from different UEs> SL CSI-RS transmission with or without repetition in the transmit beam (Agreement(#112b)To study the feasibility of reusing SL CSI-RS for initial beam pairing,at least the following enhancements can be considered.> SL CSI-RS transmission with or without sidelink data transmission in the same slot>> FFS: slot structure> Mapping between SL CSI-RS transmission / resource and beam related information> Periodic SL CSI-RS transmission, semi-persistent SL CSI-RS transmission, or aperiodic SL CSI-RS transmission, with or without SCI indication> Allocation of SL CSI-RS beam sweeping resources and if applicable, their associated beam reporting resources> Study the possibility to apply SL CSI-RS for initial beam pairing before, during or after unicast link establishment>> FFS: How to provide SL CSI-RS resource configuration> Whether or how to mitigate / avoid the interference between overlapped SL CSI-RS transmissions from different UEs> SL CSI-RS transmission with or without repetition on transmit beams)합의 (#113)사이드링크 유니캐스트 링크 설정 이전에 초기 빔 페어링이 수행되는 후보 절차에 있어서,> 스텝 1에서,>> Applicable reference signals are selected based on >>> Alt 1-1: S-SSB or modified format >>> Alt 1-2: Standalone SL CSI-RS or modified format >>> Alt 1-3: Non-standalone SL CSI-RS >>>> Note: Standalone SL CSI-RS transmission implies at least no accompanying sidelink data (SL MAC SDU) transmission in the same slot. FFS: Accompanying SCI(s) or SL MAC CE transmission or PSFCH. >>> Alt 1-4: PSCCH / PSSCH DMRS >> Reference signal transmission >>> Alt 2-0: Aperiodic >>> Alt 2-1: Periodic >>> Alt 2-2: Semi-static with activation and deactivation >>>> Details of FFS activation / deactivation >> FFS resource and reference signal resource allocation >> FFS: If CSI-RS is used, whether UE1 transmits other information related to CSI-RS >> In Step 2 >> The transmit beam of UE1 and the receive beam of UE2 are determined by UE2 pairwise with RSRP measurements satisfying certain condition(s) >>> Details of FFS condition(s) >>> Explicit or implicit determination of UE1 transmit beam by FFS UE2 >> At least assuming beam correspondence,UE2's transmit beam is determined to correspond at least to the determined UE2's receive beam>>> FFS Other Methods> In step 3>> UE2's beam report is associated with the determined UE1's transmit beam.>>> FFS Association Details>>> Details of FFS Beam Report>> Note: This does not exclude beam reporting in the link establishment message.>> FFS: How to determine the transmit beam when UE1 receives different beam reports from different UEs> FFS: Whether / how to prevent unnecessary beam measurements and reports from multiple UEs; (Agreement (#113) In the candidate procedure where initial beam pairing is performed before sidelink unicast link establishment,> In step 1,>> the applicable reference signal is selected based on>>> Alt 1-1: S-SSB or its modified format>>> Alt 1-2: standalone SL CSI-RS or its modified format>>> Alt 1-3: non-standalone SL CSI-RS>>>> Note: standalone SL CSI-RS transmission means at least no accompanying sidelink data (SL MAC SDU) transmissions in the same slot. FFS: accompanying SCI(s) or SL MAC CE transmissions or PSFCH.>>> Alt 1-4: PSCCH / PSSCH DMRS>> the reference signals are sent>>> Alt 2-0: aperiodically>>> Alt 2-1: periodically>>> Alt 2-2: semi-persistent with activation and deactivation>>>>FFS details of activation / deactivation>> FFS resources and resource allocation of reference signal>> FFS: if CSI-RS is used, whether UE1 transmits other information associated with the CSI-RS> In step 2,>> UE1's transmit beam and UE2's receive beam are determined by UE2 as the pair with the RSRP measurement satisfying certain condition(s)>>> FFS details of condition(s)>>> FFS explicit or implicit determination of UE1 transmit beam by UE2>> UE2's transmit beam is at least determined as the one corresponding to determined UE2's receive beam, at least if beam correspondence is assumed>>> FFS other scheme> In step 3,>> UE2's beam reporting is associated with determined UE1's transmit beam.>>> FFS details of association>>> FFS details of beam reporting>>> Note: this does not preclude beam reporting in the link establishment message.>> FFS: how UE1 determines its transmit beam if it receives different beam reporting from different UEs> FFS: whether / how to avoid unnecessary beam measurement and reporting from multiple UEs;)합의 (#113)사이드링크 유니캐스트 링크 설정 동안 초기 빔 페어링이 수행되는 후보 절차에 있어서,> 스텝1에서,A candidate reference signal transmitted with a unicast link setup message is selected based on one of the following alternatives>> Alt 1-1: SL CSI-RS>> Alt 1-2: PSCCH / PSSCH DMRS> In step 2, UE2 determines the transmit beam(s) of UE1 and the receive beam(s) of UE2 as a pair based on RSRP measurements satisfying certain condition(s).>> At least assuming beam correspondence, the transmit beam of UE2 is determined to be a beam corresponding to the determined receive beam of UE2.>> Format of the transmit beam of UE1 determined by FFS UE2. For example, implicit or explicit FFS condition(s) details> In step 2, UE2 indicates the transmit beam(s) of UE1.>> Details of the beam indication, including FFS contents (e.g., ACK / NACK, beam ID, RSRP measurement), containers (e.g., PSCCH / PSSCH, PSFCH) and associations (e.g., resources)> In step 3, UE1 determines the transmit beam of UE1 based on one or more of the following alternatives>> Alt 2-1: Recent beam indication>> Alt 2-2: Beam indication contents (e.g., RSRP measurement)>> Alt 2-3: Measurement / detection of beam indication signal (Agreement (#113) In the candidate procedure where initial beam pairing is performed during sidelink unicast link establishment,> In step 1, the candidate reference signal which is transmitted together with unicast link establishment message is selected based on one of the following alternatives>> Alt 1-1: SL CSI-RS>> Alt 1-2: PSCCH / PSSCH DMRS> In step 2,UE2 determines UE1's transmit beam(s) and UE2's receive beam(s) as the pair with the RSRP measurement satisfying certain condition(s).>> UE2's transmit beam is at least determined as the one corresponding to determined UE2's receive beam, at least if beam correspondence is assumed>> FFS the format of UE1's transmit beam determined by UE2, e.g. implicit or explicit>> FFS details of condition(s)> In step 2, UE2 indicates UE1's transmit beam(s).>> FFS details of beam indication, including contents (e.g., ACK / NACK, beam ID, RSRP measurement), container (e.g., PSCCH / PSSCH, PSFCH) and association (e.g. resources)> In step 3, UE1 determines UE1's transmit beam based on one or more of the following alternatives>> Alt 2-1: the latest beam indication>> Alt 2-2: beam indication contents (e.g., RSRP measurement)>> Alt 2-3: measurement / detection of beam indication signal),

[0062] This specification proposes a communication scheme for performing initial beam pairing operations together with unicast link establishment for sidelink (SL) communication. Preferably, the SL communication scheme is proposed for performing initial beam pairing operations during the unicast link establishment procedure in the FR2 (frequency range 2) band.

[0063] For convenience of explanation, in this specification, UE1 is used as a terminal transmitting data / signal in SL communication, and UE2 is used as a target terminal receiving data / signal from UE1. In addition, the transmission beam used for data / signal transmission is referred to as TX beam, and the reception beam used for data / signal reception is referred to as RX beam.

[0064] FIG. 6 is an example of signaling for performing initial beam pairing and unicast link establishment according to one embodiment of the present specification.

[0065] The initial beam pairing in Fig. 6 is performed simultaneously through the unicast link establishment process.

[0066] Referring to FIG. 6, UE1 transmits a direct link establishment request (DCR) message to UE2 (S601), and UE2 transmits a direct link establishment accept (DCA) message to UE1 (S602), thereby completing unicast link establishment. Here, the DCR message can be transmitted together with other RSs (reference signals) in the form of beam sweeping (S601). UE2 acquires beam information during the process of receiving the DCR message and RSs, and based on the acquired beam information, transmits a DCA message including beam reporting for beam information transmission to UE1 using a specific beam or specific resource (S602).

[0067] The DCR message of Fig. 6 can be transmitted in the form of beam sweeping within a beam sweeping period. At this time, the beam sweeping period can be indicated through a master information block (MIB), a system information block (SIB), and / or a radio resource control (RRC) / medium access control (MAC)-CE (control element), and can be set and operated in an SL-specific or resource pool-specific form.

[0068] FIG. 7 illustrates an example of beam sweeping according to one embodiment of the present specification.

[0069] Referring to FIG. 7, an example is shown in which a DCR message is transmitted in a beam sweeping format through six beams during one beam sweeping cycle.

[0070] FIG. 8 illustrates an example of a sidelink slot configuration according to one embodiment of the present specification.

[0071] Fig. 8 is an example of a configuration of one SL slot when a DCR message is transmitted through one or more SL slots. Referring to Fig. 8, a slot consisting of 13 symbols is configured with one AGC (automatic gain control) symbol, one PSCCH symbol, eight PSSCH symbols, one guard symbol, and two DM-RS (demodulation-reference signal) symbols. The number of PSSCH symbols and DM-RS symbols in the corresponding SL slot can be configured in various forms. In addition, it can also be configured in a form that includes a CSI-RS symbol.

[0072] One SL slot includes an AGC symbol and a guard symbol, and one SL slot consists only of PSCCH and DM-RS, or an SL slot can consist only of PSCCH and CSI-RS, or only of PSCCH, PSSCH, and DM-RS, or only of PSCCH, PSSCH, and CSI-RS. In this case, a DM-RS for PSCCH and PSSCH decoding can be included in an SL slot consisting only of PSCCH and CSI-RS and an SL slot consisting only of PSCCH, PSSCH, and CSI-RS.

[0073] In the example of Fig. 8, it is assumed that all RSs are transmitted on the same beam. Therefore, within one SL slot, UE2 can perform measurements by changing the receiving beam for the same beam, and based on this, information about the transmit / receive beam pairs for UE1 and UE2 can be obtained.

[0074] In the example of FIG. 8, some DM-RSs or some CSI-RSs transmitted within an SL slot may be transmitted on beams different from those for the PSCCH, PSSCH, and DM-RSs for decoding the PSCCH and PSSCH. In this case, a terminal (e.g., UE2) can measure multiple UE1 TX beams within a single SL slot.

[0075] FIGS. 9A and 9B illustrate examples of transmitting a DCR message and a CSI-RS within a beam sweeping period according to one embodiment of the present specification.

[0076] Unlike the method of transmitting together with RS in SL slot including PSCCH and PSSCH that transmit DCR message as shown in FIG. 8 above, an additional RS signal can be transmitted together when transmitting DCR message as shown in FIG. 9a and FIG. 9b. FIG. 9a assumes that three DCR messages are beam-sweeping transmitted within a beam-sweeping period. In addition, this is an example in which the location of CSI-RS transmission resources is set / fixed and operated by setting time and frequency resource offset values ​​based on the time and frequency resource location of each DCR message transmission. The offset value of the time / frequency resource where CSI-RS is transmitted based on the DCR message transmission resource location or the setting for a specific time / frequency resource location can be systematically fixed and set, and can be indicated through the DCR message or the MIB of the S-SSB. Or it can be indicated through RRC / MAC-CE, etc. The setting can be set and operated in an SL specific or resource pool specific form. In the example of Fig. 9a, the transmission beam of the DCR message can be configured as a beam with a wider beam width than the CSI-RS transmission beam. In addition, the CSI-RS beam transmitted after each DCR message can be set to a narrow beam within the S-SSB transmission beam width immediately before the CSI-RS transmission and used. Fig. 9a shows an example in which the CSI-RS is configured and operated with three symbols, and an example in which the CSI-RS transmitted through each symbol is transmitted with a different beam. The size of the resource for transmitting the CSI-RS, such as the number of symbols or the number of slots used, can be indicated through MIB or RRC / MAC-CE, etc., and can be set and operated in an SL-specific or resource pool-specific form.UE2 according to the example of FIG. 9a can obtain beam pairing information through the successfully received DCR message and CSI-RSs transmitted thereafter after successfully receiving a specific DCR message.

[0077] Fig. 9b assumes that three DCR messages are transmitted using beam sweeping within a beam sweeping period. Unlike Fig. 9a, this is an example in which CSI-RS is transmitted continuously after all DCR messages are transmitted using beam sweeping. The CSI-RS transmission resources in Fig. 9b can be configured and operated in the same manner as described in Fig. 9a. However, Fig. 9b shows an example in which the CSI-RS is transmitted using nine symbols on nine different beams. After UE2 successfully receives a specific DCR message, it can obtain beam pairing information through the successfully received DCR message and the CSI-RSs transmitted thereafter.

[0078] Some or all of the CSI-RS transmission beams described in FIGS. 9a to 9b may be transmitted in the same beam, and the CSI-RSs transmitted in the same beam may be utilized for measurement purposes for setting the reception beam of UE2.

[0079] FIGS. 10A and 10B are further examples of signaling for performing initial beam pairing and unicast link establishment according to one embodiment of the present disclosure.

[0080] FIGS. 10A and 10B are examples of performing initial beam pairing and unicast link establishment, and are different examples from the previously described FIG. 6. In FIG. 10A, UE2 receives a DCR message and RSs (S1001a), acquires beam information through this reception process, and performs beam reporting for beam information transmission using a specific beam or specific resource based on the acquired beam information (S1002a). Afterwards, since the initial beam pairing is completed, UE2 transmits a DCA message using the beam pair, and UE1 receives the DCA message (S1003a) to complete unicast link establishment.

[0081] FIG. 10b is an example of a method in which, after beam reporting of UE2 in FIG. 10a, UE1 transmits a beam pairing response message to UE2 indicating that initial beam pairing is completed (S1003b), and after receiving the response message, UE2 sends a DCA message (S1004b) to complete unicast link establishment. For reference, S1001b and S1002b in FIG. 10b are signaling corresponding to S1001a and S1002a in FIG. 10a, respectively, and may correspond to the content of FIG. 10a described above.

[0082] The DCR message transmission scheme proposed in FIG. 6, FIG. 10a and FIG. 10b of this specification can be applied in simple, extended and / or modified forms.

[0083] In the procedures of FIGS. 6, 10A, and 10B of this specification, a timer (e.g., T5000) for performing unicast link establishment may be applied and operated. The timer may start at the time of transmitting the first DCR message. In addition, beam sweeping transmission of all DCR messages and DCA message transmission of UE2 may be set and operated to be completed before the timer (e.g., T5000) expires.

[0084] In the operation of the procedures of FIGS. 10A and 10B, UE2 may operate to transmit beam reporting within a specific time offset from the time at which UE1's DCR message and RS transmission are completed. For example, since beam information measured by UE2 may no longer be valid due to changes in the channel over time after UE1 transmits RS and DCR messages for beam pairing, UE2 may perform beam reporting based on beam-related information acquired within a specific time offset after transmitting RS and DCR messages for beam pairing. If UE2 performs beam reporting after a specific time offset, information about the corresponding beam pair may be discarded by UE1 and not used. In addition, if UE1 does not receive beam reporting within a specific time offset, UE1 may transmit RS and DCR messages for beam pairing again.

[0085] In the operation of the procedure of FIG. 10a and / or FIG. 10b, the DCA message may be transmitted within a specific time offset after UE2's beam reporting. For example, since the beam pair acquired through beam pairing may no longer be valid due to channel changes over time, the DCA message may be transmitted using the beam pair acquired through the beam pairing procedure within a specific time offset after the beam reporting. If the DCA message is not received within the time offset, UE1 may perform DCR message and RS beam sweeping transmission again.

[0086] In the procedure operation of FIG. 10b, if UE2 does not receive a beam pairing response within a specific time offset after transmitting beam reporting, it may attempt to receive a DCR message and RS for initial beam pairing with UE1 without attempting to transmit a DCA message. Alternatively, UE2 may attempt to transmit a DCA message a set number of times even if a beam response is not received after transmitting beam reporting. The number of attempts may be 1 or more. Alternatively, it may attempt to transmit a DCA message until a timer (e.g., T5000) expires. Afterwards, if unicast link establishment fails, UE1 may perform the unicast link establishment and initial beam pairing procedures again.

[0087] Additionally, in the procedure operation of FIG. 10b, UE1 can be configured and operated to receive a DCA message within a specific time offset after transmitting a beam pairing response. If the specific time offset is exceeded, UE1 can perform the unicast link establishment and initial beam pairing procedures again.

[0088] The specific time offset values, number of DCA message transmission attempts, etc. described above can be used as fixed values ​​in the system, or can be set and operated in a resource pool-specific or SL-specific manner. In the case where a specific time offset value is set, the offset value can be set using signaling that can be used in the corresponding procedure. For example, it can be set through the DCR message, MIB transmitted through the PSBCH of the S-SSB, SIB, SCI of the PSCCH, PSSCH, PSFCH, MAC-CE, RRC, etc.

[0089] Additionally, the transmission of the DCR message in the form of beam sweeping within the beam sweeping cycle described so far can be similarly applied to the transmission of the DCA message.

[0090] Below, a description is given of a device to which this specification can be applied.

[0091] FIG. 11 illustrates a wireless communication device according to one embodiment of the present specification.

[0092] Referring to FIG. 11, a wireless communication system may include a first device (100) and a second device (200).

[0093] The first device (100) may be a base station, a network node, a transmitting terminal, a receiving terminal, a wireless device, a wireless communication device, a vehicle, a vehicle equipped with an autonomous driving function, a connected car, a drone (Unmanned Aerial Vehicle, UAV), an AI (Artificial Intelligence) module, a robot, an AR (Augmented Reality) device, a VR (Virtual Reality) device, an MR (Mixed Reality) device, a hologram device, a public safety device, an MTC device, an IoT device, a medical device, a fintech device (or a financial device), a security device, a climate / environmental device, a device related to 5G services, or any other device related to the 4th industrial revolution field.

[0094] The second device (200) may be a base station, a network node, a transmitting terminal, a receiving terminal, a wireless device, a wireless communication device, a vehicle, a vehicle equipped with an autonomous driving function, a connected car, a drone (Unmanned Aerial Vehicle, UAV), an AI (Artificial Intelligence) module, a robot, an AR (Augmented Reality) device, a VR (Virtual Reality) device, an MR (Mixed Reality) device, a hologram device, a public safety device, an MTC device, an IoT device, a medical device, a fintech device (or a financial device), a security device, a climate / environmental device, a device related to 5G services, or a device related to other fields of the 4th industrial revolution.

[0095] The first device (100) may include at least one processor, such as a control unit (1020), at least one memory, such as a memory unit (1030), and at least one transceiver, such as a transceiver unit (1010). In addition, the first device (100) may further include a power supply unit (1040) that supplies and controls power to the control unit (1020), the memory unit (1030), and / or the transceiver unit (1010). The control unit (1020) may perform the functions, procedures, and / or methods described above. The control unit (1020) may perform one or more protocols. For example, the control unit (1020) may perform one or more layers of a wireless interface protocol. The memory unit (1030) may be connected to the control unit (1020) and may store various types of information and / or commands. The above transmitting and receiving unit (1010) is connected to the control unit (1020) and can be controlled to transmit and receive wireless signals.

[0096] The second device (200) may include at least one processor, such as a control unit (2020), at least one memory, such as a memory unit (2030), and at least one transceiver, such as a transceiver unit (2010). In addition, the second device (200) may further include a power supply unit (2040) that supplies and controls power to the control unit (2020), the memory unit (2030), and / or the transceiver unit (2010). The control unit (2020) may perform the functions, procedures, and / or methods described above. The control unit (2020) may perform one or more protocols. For example, the control unit (2020) may perform one or more layers of a wireless interface protocol. The memory unit (2030) may be connected to the control unit (2020) and may store various types of information and / or commands. The above transmitting and receiving unit (2010) is connected to the control unit (2020) and can be controlled to transmit and receive wireless signals.

[0097] The memory unit (1030) and / or the memory unit (2030) may be connected to the control unit (1020) and / or the control unit (2020) either internally or externally, respectively, and may be connected to other control units via various technologies such as wired or wireless connections.

[0098] The first device (100) and / or the second device (200) may have one or more antennas. For example, the antenna (1050) and / or the antenna (2050) may be configured to transmit and receive wireless signals.

[0099] Although the preferred embodiments have been described above by way of example, the disclosure of this specification is not limited to these specific embodiments, and may be modified, changed, or improved in various forms within the scope described in the spirit and claims of this specification.

Claims

1. In a method for a transmitting terminal to perform sidelink communication, a step of transmitting a direct link establishment request (DCR) message; and Including a step of receiving a direct link establishment accept (DCA) message in response to the direct link establishment request message transmitted above, The above direct link setup request message is transmitted together with a reference signal (RS) for beam pairing, A method wherein at least one of the direct link establishment request message and the direct link establishment acceptance message is repeated within a specific cycle.

2. In paragraph 1, A method further comprising the step of receiving beam reporting based on the transmitted reference signal.

3. In paragraph 2, A method further comprising the step of transmitting a beam pairing response, wherein the beam pairing response is transmitted prior to receiving the direct link establishment acceptance message.

4. In paragraph 2, The above beam reporting is received based on a first specific time offset, 5. In paragraph 2, A method wherein the above direct link establishment acceptance message is received based on a second specific time offset.

6. In paragraph 1, A method wherein the above reference signal is at least one of a sidelink-synchronization signal block (S-SSB), a sidelink channel state information-reference signal (CSI-RS), and a sidelink channel demodulation-reference signal (DM-RS).

7. In paragraph 1, A method wherein the above reference signal is repeatedly transmitted within the specific period together with the above direct link establishment request message.

8. In a method for a receiving terminal to perform sidelink communication, A step of receiving a direct link establishment request (DCR) message; and Including a step of transmitting a direct link establishment accept (DCA) message in response to the received direct link establishment request message, The above direct link setup request message is received together with a reference signal (RS) for beam pairing, A method wherein at least one of the direct link establishment request message and the direct link establishment acceptance message is repeated within a specific cycle.

9. In paragraph 8, A method further comprising the step of transmitting beam reporting based on the received reference signal.

10. In paragraph 9, A method further comprising the step of receiving a beam pairing response, wherein the beam pairing response is received prior to transmitting the direct link establishment accept message.

11. In paragraph 9, The above beam reporting is transmitted based on a first specific time offset, 12. In paragraph 9, The above direct link establishment acceptance message is transmitted based on a second specific time offset, 13. In paragraph 1, A method wherein the above reference signal is at least one of a sidelink-synchronization signal block (S-SSB), a sidelink channel state information-reference signal (CSI-RS), and a sidelink channel demodulation-reference signal (DM-RS).

14. In paragraph 8, A method wherein the above reference signal is received repeatedly within the specific period together with the above direct link establishment request message.

15. As a transmitting terminal performing sidelink communication, control unit; and A memory unit storing instructions and being operably electrically connectable to the control unit, wherein the operations performed based on the instructions being executed by the control unit are: A step for sending a direct link establishment request (DCR) message, and Including a step of receiving a direct link establishment accept (DCA) message in response to the direct link establishment request message transmitted above, The above direct link setup request message is transmitted together with a reference signal (RS) for beam pairing, A transmitting terminal, wherein at least one of the direct link establishment request message and the direct link establishment acceptance message is repeated within a specific cycle.

16. In paragraph 15, Based on the above command being executed by the above control unit, the operations performed are: A transmitting terminal further comprising a step of receiving beam reporting based on the transmitted reference signal.

17. In paragraph 16, Based on the above command being executed by the above control unit, the operations performed are: A transmitting terminal further comprising a step of transmitting a beam pairing response, wherein the beam pairing response is transmitted prior to receiving the direct link establishment acceptance message.

18. As a receiving terminal performing sidelink communication, control unit; and A memory unit storing instructions and being operably electrically connectable to the control unit, wherein the operations performed based on the instructions being executed by the control unit are: A step for receiving a direct link establishment request (DCR) message, and Including a step of transmitting a direct link establishment accept (DCA) message in response to the received direct link establishment request message, The above direct link setup request message is received together with a reference signal (RS) for beam pairing, A receiving terminal, wherein at least one of the direct link establishment request message and the direct link establishment acceptance message is repeated within a specific cycle.

19. In paragraph 18, Based on the above command being executed by the above control unit, the operations performed are: A receiving terminal further comprising a step of transmitting beam reporting based on the received reference signal.

20. In paragraph 19, Based on the above command being executed by the above control unit, the operations performed are: A receiving terminal further comprising a step of receiving a beam pairing response, wherein the beam pairing response is received prior to transmitting the direct link establishment acceptance message.

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