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

Abstract

Provided are a method and an apparatus for initial beam pairing before unicast link establishment in sidelink communication. A transmission terminal according to a disclosure of the present specification transmits, to a reception terminal, a reference signal (RS) for beam pairing, and receives, from the reception terminal, beam reporting based on the transmitted reference signal. The transmission terminal transmits, on the basis of the received beam reporting, a direct link establishment request (DCR) message to the reception terminal, and receives a direct link establishment accept (DCA) message from the reception terminal in response to the transmitted direct link establishment request.

Description

Method and device for initial beam pairing prior to 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] Meanwhile, as more and more communication devices demand ever-increasing communication traffic, the demand 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 prior to unicast link establishment between terminals for sidelink communication in a wireless communication system.

[0007] One embodiment of the present specification provides a method for sidelink (SL) communication, in which a transmitting terminal transmits a reference signal (RS) for beam pairing to a receiving terminal and receives beam reporting based on the transmitted reference signal from the receiving terminal. The transmitting terminal transmits a direct link establishment request (DCR) message to the receiving terminal based on the received beam reporting, and receives a direct link establishment accept (DCA) message from the receiving terminal in response to the transmitted direct link establishment request.

[0008] In addition, one embodiment of the present specification provides a method in which, in sidelink (SL) communication, a receiving terminal receives a reference signal (RS) for beam pairing from a transmitting terminal, and transmits beam reporting based on the received reference signal to the transmitting terminal. The receiving terminal receives a direct link establishment request (DCR) message based on the transmitted beam reporting from the transmitting terminal, and transmits a direct link establishment accept (DCA) message to the transmitting terminal in response to the received direct link establishment request.

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

[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 reference signal (RS) for beam pairing, transmitting beam reporting based on the received reference signal, receiving a direct link establishment request (DCR) message based on the transmitted beam reporting, and transmitting a direct link establishment accept (DCA) message in response to the received direct link establishment request.

[0011] Meanwhile, the transmitting terminal may transmit a beam pairing response to the receiving terminal, wherein the direct link establishment request message may include the beam pairing response. As another example, the beam pairing response may be transmitted as a separate message prior to transmitting the direct link establishment request message.

[0012] The above direct link setup request message can be transmitted (or received) based on a specific time offset.

[0013] 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).

[0014] Additionally, the reference signal may include identifier information of the transmitting terminal and / or the receiving terminal.

[0015] 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.

[0016] 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.

[0017] Figure 1 is a diagram illustrating an NR wireless communication system.

[0018] Figure 2 illustrates the structure of a radio frame used in NR.

[0019] Figure 3 illustrates the slot structure of an NR frame.

[0020] Figure 4 is an example showing an NG-RAN architecture supporting the PC5 interface.

[0021] Figures 5a and 5b illustrate a procedure for performing sidelink communication according to a sidelink resource allocation mode.

[0022] FIGS. 6A and 6B are examples of signaling for performing initial beam pairing and unicast link establishment according to one embodiment of the present specification.

[0023] FIGS. 7A to 7D illustrate examples of beam sweeping within an S-SSB transmission cycle according to one embodiment of the present disclosure.

[0024] FIGS. 8A and 8B illustrate examples of CSI-RS transmission in a standalone form in conjunction with beam sweeping of S-SSB according to one embodiment of the present specification.

[0025] FIG. 9 illustrates an example in which a sidelink slot according to one embodiment of the present specification is transmitted in a beam sweeping form through six beams during one beam sweeping period.

[0026] FIG. 10 illustrates an example of a sidelink slot configuration according to one embodiment of the present specification.

[0027] FIG. 11 illustrates a wireless communication device according to one embodiment of the present specification.

[0028] 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.

[0029] 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.

[0030] 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.

[0031] 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.

[0032] 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).

[0033] Frequency Range designationCorresponding frequency rangeSubcarrier SpacingFR1410MHz - 7125MHz15, 30, 60kHzFR224250MHz - 52600MHz60, 120, 240kHz

[0034] 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).

[0035] Figure 1 is a diagram illustrating an NR wireless communication system.

[0036] 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.

[0037] 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.

[0038] Figure 2 illustrates the structure of a radio frame used in NR.

[0039] 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).

[0040] 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.

[0041] 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

[0042] N slot symb : Number of symbols in the slot

[0043] N frame,u slot : Number of slots in the frame

[0044] ​​N subframe,u slot : Number of slots in a subframe

[0045] 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.

[0046] SCS (15*2 u )N slot symb N frame,u slot N subframe,u slot 60KHz (u=2)12404

[0047] 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.

[0048] Figure 3 illustrates the slot structure of an NR frame.

[0049] ​​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.

[0050] Figure 4 is an example showing an NG-RAN architecture supporting the PC5 interface.

[0051] 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.

[0052] 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.

[0053] 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.

[0054] Figures 5a and 5b illustrate a procedure for performing sidelink communication according to a sidelink resource allocation mode.

[0055] 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.

[0056] 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).

[0057] 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.

[0058] Meanwhile, technologies for performing initial beam pairing and unicast link establishment for sidelink communication in the FR2 (frequency range 2) band are currently under development. This specification proposes a procedure and detailed technology for performing initial beam pairing prior to unicast link establishment. In particular, it proposes a reference signal (RS) and message used to transmit beam information during the initial beam pairing operation, and a resource allocation method and / or operation method for transmitting the corresponding signal / data. In addition, when performing initial beam pairing prior to unicast link establishment, the receiving terminal performs the initial beam pairing without knowing whether the transmitting terminal currently performing the beam pairing procedure is a terminal for establishing a unicast link establishment. Therefore, the receiving terminal may perform unnecessary beam pairing procedures. In this specification, to minimize the above-mentioned unnecessary beam pairing procedures, it proposes a method in which identifier information is transmitted through the reference signal and message transmitted by the transmitting terminal for initial beam pairing.

[0059] 3GPP is discussing beam-related technologies for sidelink communications in the FR2 band, and Table 4 below shows part of the related agreement.

[0060] 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 shall include at least the following steps and a method for determining UE2: The following candidate procedures can be studied where initial beam pairing is performed prior to sidelink unicast link establishment:> UE1 transmits reference signals over different transmit beams>> Note: Multiple reference signal transmissions from each beam (e.g.,> FFS: When reference signals are transmitted > FFS applicable reference signal > UE2 measures the reference signals and determines a UE1 transmit beam and / or a UE2 receive beam > FFS: Whether / how to determine UE2 transmit beam > UE2 indicates the determined UE1 transmit beam to UE1 > FFS: Method of indicating the determined transmit beam, including its validity > UE1 and UE2 establish a sidelink unicast link using the beam determined according to the existing link establishment procedure (Agreement (#112b) > RAN1 can study the following candidate procedure where initial beam pairing is performed before sidelink unicast link establishment, including at least the following steps and how to determine UE2: > UE1 sends reference signals via different transmit beams > Note: multiple reference signal transmissions (e.g. repetitions) from each of the beams can be studied > FFS when reference signals are sent > FFS applicable reference signal > UE2 measures the reference signals and determines a UE1 transmit beam and / or a UE2 receive beam>>FFS: whether / how to determine a UE2 transmit beam> UE2 indicates to UE1 the determined UE1 transmit beam>> FFS how to indicate the determined transmit beam,including its feasibility> UE1 and UE2 set up sidelink unicast link using the determined beam, following existing link establishment procedure.)Agreement (#112b)To study the applicability of S-SSB for initial beam pairing between UE1 and UE2, at least the following may be considered:> Whether / how UE2 identifies UE1 (e.g., source ID) from UE1's S-SSB transmission, and whether / how UE1 identifies corresponding beam measurements / reports from UE2> Mapping of S-SSB transmissions / resources and beam-related information> Assignment of beam reporting resources associated with different S-SSB transmit beams, respectively> Structure and content of S-SSB> Triggering and / or activating S-SSB transmissions, if necessary> S-SSB monitoring and reporting / response mechanisms> Mechanisms 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 such impacts are avoided or mitigated. (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 (eg, 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 improvements 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 transmission / resource and beam related information> Periodic SL with or without SCI indication CSI-RS transmission, semi-static SL CSI-RS transmission or aperiodic SL CSI-RS transmission > allocation of SL CSI-RS beam sweeping resources and, if applicable, associated beam reporting resources > prior to unicast link establishment,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) Agreement (#113) In the candidate procedure where initial beam pairing is performed prior to sidelink unicast link establishment,> in Step 1,>> the applicable reference signal is 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: A 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,The transmit beam of UE2 is determined to correspond at least to the determined receive beam of UE2>>> FFS Other Methods> In step 3>> The beam report of UE2 is associated with the determined transmit beam of UE1.>>> 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;),

[0061] This specification proposes a communication method for sidelink (SL) communication in which initial beam pairing is performed prior to unicast link establishment. Preferably, the SL communication method is proposed in the frequency range 2 (FR2) band in which initial beam pairing is performed prior to unicast link establishment.

[0062] 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.

[0063] FIGS. 6A and 6B are examples of signaling for performing initial beam pairing and unicast link establishment according to one embodiment of the present specification.

[0064] Initial beam pairing in FIGS. 6A and 6B is performed prior to unicast link establishment.

[0065] Referring to FIG. 6a, UE1 transmits a reference signal (RS) for beam pairing in the form of beam sweeping (S601a). Thereafter, UE2 performs measurement on the corresponding RSs transmitted to specific beams and selects beam(s) to be used for SL communication based on the received information. Thereafter, information on the corresponding beam(s) is reported to UE1 (S602a). Initial beam pairing between UE1 and UE2 is completed by the signaling procedure. Thereafter, UE1 transmits a direct link establishment request (DCR) message to UE2 for unicast link establishment using the TX beam(s) acquired by the beam pairing procedure (S603a). At this time, UE2 receives the DCR message using the RX beam(s) acquired by the initial beam pairing procedure.

[0066] Upon successfully receiving the DCR message, UE2 transmits a direct link establishment accept (DCA) message to UE1 (S604a), thereby completing the unicast link establishment procedure. The TX beam of UE2 and the RX beam of UE1 for transmitting and receiving the DCA message can be set based on the beam information acquired through the beam pairing procedure.

[0067] In the operation of the procedure of FIG. 6a, a DCR message can be transmitted within a specific time offset after UE2's beam reporting. For example, since a beam pair acquired through beam pairing may no longer be valid due to channel changes over time, a DCR message can be transmitted using a beam pair acquired through the beam pairing procedure within a specific time offset after beam reporting. If the DCR message cannot be transmitted within the time offset, UE1 can perform the beam pairing procedure again.

[0068] In the operation of the procedure of FIG. 6a, UE2 can operate to transmit beam reporting within a specific time offset from the time when UE1's RS transmission for beam pairing ends. For example, since the beam information measured by UE2 may no longer be valid due to changes in the channel over time after UE1's RS transmission for beam pairing, beam reporting can be performed based on the acquired beam-related information within a specific time offset after UE1's RS transmission for beam pairing. If UE2 performs beam reporting after a specific time offset, the information for 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 can transmit RSs for beam pairing again. For example, this operation can be applied and operated when RS transmission for beam pairing is transmitted in an aperiodic form or a semi-persistent form.

[0069] The above specific time offset values ​​can be used as fixed values ​​in the system, or can be operated by setting them 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 beam procedure procedure. For example, it can be set through the master information block (MIB), system information block (SIB), sidelink control information (SCI) of the physical sidelink control channel (PSCCH), physical sidelink shared channel (PSSCH), physical sidelink feedback channel (PSFCH), medium access control-control element (MAC-CE), and / or radio resource control (RRC) transmitted through the physical sidelink broadcast channel (PSBCH) of the S-SSB.

[0070] In the operation of FIG. 6a, the DCR message may include a beam pairing response message. In this case, UE2 recognizes that beam pairing with UE1 has been successful, regardless of unicast link establishment, and can utilize beam pairing information in subsequent signaling procedures with UE1.

[0071] Meanwhile, Fig. 6b is an example of signaling with a beam pairing response message added in the beam pairing procedure. This signaling may be transmitted if the initial beam pairing is successfully completed (S603b). For reference, S601b, S602b, S604b, and S605b of Fig. 6b correspond to signaling corresponding to S601a, S602a, S603a, and S604a of Fig. 6a, respectively, and may correspond to the content of Fig. 6a described above.

[0072] The beam pairing response message may include all or part of the following information: beam information that UE1 uses for transmission, beam information that UE2 should use, unicast L2 (layer 2) ID of UE1 or source L2 ID or application layer ID of UE1 or unicast L2 ID of UE2 or destination L2 ID or V2X service ID or L1 ID of UE1 or L1 ID of UE2.

[0073] The Initial beam pairing response message may indicate the transmission of a DCR message. In this case, UE2 may attempt to receive a DCR message after receiving the beam pairing response message. For example, it may begin monitoring the PSCCH used for DCR message transmission. Additionally, the beam pairing response message may include all or part of the information about the resource on which the DCR message is transmitted.

[0074] In the operation of the procedure of FIG. 6b, the operation in which the next signal is transmitted within a specific time offset between signalings used in FIG. 6a can be simply applied, extended, and modified. For example, if UE2 does not receive a beam pairing response within a specific time offset after transmitting beam reporting, it may attempt to receive an RS for beam pairing of UE1 without attempting to receive a DCR message. Alternatively, if UE2 receives a DCR message within a specific time offset after transmitting beam reporting, even if no beam response is received, it may determine that beam pairing is complete and proceed with the subsequent procedure. If it does not receive a DCR message within a specific time offset after transmitting beam reporting, it may no longer attempt to receive a DCR message and attempt to receive an RS for beam pairing of UE1.

[0075] Additionally, in the operation of the procedure of FIG. 6b, UE1 can be configured and operated to transmit a DCR message within a specific time offset after transmitting a beam pairing response. If the specific time offset is exceeded, UE1 can perform the beam pairing procedure again.

[0076] The above specific time offset values ​​can be used as fixed values ​​in the system, or can be operated by setting them 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 beam procedure. For example, it can be set through the MIB, SIB transmitted through the PSBCH of the S-SSB, SCI of the PSCCH, PSSCH, PSFCH, MAC-CE, and / or RRC.

[0077] In the examples of FIGS. 6A and / or 6B described above, the RS transmitted by UE1 may be an S-SSB, an SL CSI-RS (channel state information-reference signal), and / or a DM-RS (demodulation-reference signal) of the PSCCH and PSSCH. The RS may be one or more of the three RSs mentioned above.

[0078] In the examples of FIGS. 6a and / or 6b, since the beam pairing procedure is performed prior to unicast link establishment, UE2 cannot determine whether the received information measured during the beam pairing procedure is for UE1, the target of unicast link establishment, until the DCR message is received. Therefore, unnecessary beam measurements are performed during the beam pairing procedure.

[0079] To minimize unnecessary beam measurement processes in UE2, the RS signal for beam pairing may include all or part of the unicast L2 ID of UE1, the source L2 ID, the application layer ID of UE1, the unicast L2 ID of UE2, the destination L2 ID, the V2X service ID, the L1 ID of UE1, or the L1 ID of UE2. In the following specification, the above-described ID information is referred to as identifier information.

[0080] As a container for transmitting the above identifier information, transmission is possible for each RS in the following manner.

[0081] In the example of FIG. 6a and / or FIG. 6b, when the RS transmitted is an S-SSB, transmission is possible through a combination of one or more containers of an MIB transmitted through a PSBCH in the S-SSB transmitted by UE1, a first SIB transmitted through a resource indicated through the MIB, a second SIB transmitted through a resource indicated through the MIB and the first SIB, or MAC-CE or RRC. At this time, the SIB may be transmitted in an omni-beam. Alternatively, the SIB may be repeated in slot or symbol units and transmitted in a beam sweeping form when transmitting the SIB for each resource unit. Alternatively, it may be transmitted by performing FDM (frequency division multiplexing) on ​​a different frequency resource in the same slot as the S-SSB and beam sweeping based on the same beam as the S-SSB.

[0082] In the above SIB transmission, identifier information can also be transmitted in a form that transmits data using PSCCH and PSSCH rather than SIB, and the resource indication for the PSCCH and PSSCH can be applied in the same way as the indication method for the SIB resource information. In this case, identifier information can be transmitted via SCI of PSCCH, PSSCH, or MAC-CE.

[0083] FIGS. 7A to 7D illustrate examples of beam sweeping within an S-SSB transmission cycle according to one embodiment of the present disclosure.

[0084] Figure 7a illustrates an example in which UE1 transmits four S-SSBs using beam sweeping with four beams within an S-SSB transmission cycle. At this time, SIB transmission resource information is included in the MIB transmitted via the PSBCH within the S-SSB, and UE1 can transmit all or part of the identifier information described above by including it in the SIB using the corresponding resources. At this time, the corresponding SIB transmission resource information may be identical in the MIB of each S-SSB.

[0085] Fig. 7b is an example of performing two beam sweeps for S-SSB transmission using three beams within an S-SSB transmission cycle. In this example, SIBs can be transmitted individually after each beam sweeping is completed. In this case, the MIB transmitted through beams #1, #2, and #3 in the first beam sweeping can indicate / include resource information of SIB#1. The MIB transmitted through beams #1, #2, and #3 in the second beam sweeping can indicate / include resource information of SIB#2. In this case, the identifier information transmitted through SIB#1 and SIB#2 can be the same.

[0086] Fig. 7c is an example of sweeping once for S-SSB transmission using 6 beams within the S-SSB transmission period. In Fig. 7c, SIB can be transmitted after S-SSB transmission with a specific number of beams within the S-SSB transmission period. The specific number can be configured in a resource pool specific, SL specific, or UE specific form. The specific number can be explicitly configured through MIB in RRC, MAC-CE, or PSBCH. Alternatively, since the transmission location of SIB can be indicated according to resource information indicated through MIB in PSBCH, it can be operated without setting the specific value. In Fig. 7c, MIB transmitted through beams #1, #2, and #3 can indicate / include resource information of SIB#1. MIB transmitted through beams #4, #5, and #6 can indicate / include resource information of SIB#2. At this time, the identifier information transmitted through SIB#1 and SIB#2 may be the same.

[0087] The SIB transmitted in the examples of FIGS. 7a, 7b, and / or 7c described above may be transmitted in an omni-beam manner. Alternatively, the SIB may be repeated in slot or symbol units, and transmitted in a beam sweeping manner when transmitting the SIB for each resource unit.

[0088] Meanwhile, Fig. 7d is an example of sweeping once for S-SSB transmission using 6 beams within the S-SSB transmission cycle. At this time, the positions of the SIBs are set to a specific frequency offset value based on the S-SSB transmission resource, so that they can be transmitted with the same beam as each S-SSB at a fixed position. The specific frequency offset value can be systematically fixed and set, and can be operated by setting it in an SL-specific or resource pool-specific form.

[0089] In the examples of FIG. 7a, FIG. 7b, FIG. 7c and / or FIG. 7d, the identifier information may be transmitted in a modified form through PSCCH and PSSCH rather than in the form of SIB.

[0090] FIGS. 8A and 8B illustrate examples of CSI-RS transmission in a standalone form in conjunction with beam sweeping of S-SSB according to one embodiment of the present specification.

[0091] In the example of FIG. 6a and / or FIG. 6b, when the transmitting RS transmits S-SSB and SL CSI-RS together, the standalone CSI-RS can be transmitted in conjunction with beam sweeping of the S-SSB. FIG. 8a is an example of this method. It is assumed that three S-SSBs are beam-sweeping transmitted within the S-SSB transmission period. In addition, this is an example in which the location of the CSI-RS transmission resource is set / fixed and operated by setting the time and frequency resource offset values ​​based on the time and frequency resource location of each S-SSB. The offset value of the time / frequency resource where the CSI-RS is transmitted based on the S-SSB resource location or the setting for a specific time / frequency resource location can be systematically fixed and set, and can be indicated through 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. 8a, the transmission beam of the S-SSB 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 S-SSB can be set to a narrow beam within the S-SSB transmission beam width immediately before the CSI-RS transmission and used. This example 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.In the example of FIG. 8a, after successfully receiving a specific S-SSB, UE2 can acquire beam pairing information through the successfully received S-SSB and the CSI-RSs transmitted thereafter. At this time, the identifier information can be acquired in a form similar to the examples of FIG. 7a, FIG. 7b, and / or FIG. 7c.

[0092] Fig. 8b assumes that three S-SSBs are transmitted using beam sweeping within an S-SSB transmission cycle. Unlike Fig. 8a, this is an example in which CSI-RS is transmitted continuously after all S-SSBs are transmitted using beam sweeping. In this example, CSI-RS transmission resources can be set and operated in the same manner as in the example of Fig. 8a. In this example, CSI-RS is transmitted using nine different beams using nine symbols. After UE2 successfully receives a specific S-SSB, it can obtain beam pairing information through the successfully received S-SSB and the CSI-RSs transmitted thereafter. At this time, identifier information can be obtained in a form similar to the examples of Fig. 7a, Fig. 7b, and / or Fig. 7c.

[0093] In the examples of FIGS. 8A and 8B, some or all of the CSI-RS transmission beams 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.

[0094] FIG. 9 illustrates an example in which a sidelink slot according to one embodiment of the present specification is transmitted in a beam sweeping form through six beams during one beam sweeping period.

[0095] In the example of FIG. 6a and / or FIG. 6b above, when the RS to be transmitted transmits PSCCH and PSSCH and CSI-RS or DM-RS within an SL slot, multiple SL slots can be transmitted in a beam sweeping form within a beam sweeping period. In this case, the beam sweeping period can be indicated through MIB or SIB or RRC / MAC-CE, etc., and can be set and operated in an SL-specific or resource pool-specific form.

[0096] Figure 9 is an example in which an SL slot is transmitted in a beam sweeping form through six beams during one beam sweeping cycle.

[0097] FIG. 10 illustrates an example of a sidelink slot configuration according to one embodiment of the present specification.

[0098] Referring to FIG. 10, a slot consisting of 13 symbols is configured with 1 AGC (automatic gain control) symbol, 1 PSCCH symbol, 5 PSSCH symbols, 1 guard symbol, 2 DM-RS symbols, and 3 CSI-RS symbols. The number of PSSCH symbols, the number of DM-RS symbols, and the number of CSI-RS symbols in the corresponding SL slot can be configured in various forms.

[0099] An SL slot may consist of only PSCCH and DM-RS, including AGC symbols and guard symbols, or may consist of only PSCCH and CSI-RS, or may consist of only PSCCH, PSSCH, and DM-RS, or may consist of only PSCCH, PSSCH, and CSI-RS. In this case, a DM-RS for PSCCH and PSSCH decoding may be included in an SL slot consisting of only PSCCH and CSI-RS and an SL slot consisting of only PSCCH, PSSCH, and CSI-RS.

[0100] In the example of Fig. 10, it is assumed that both CSI-RS and DM-RS are transmitted on the same beam. Therefore, within a single SL slot, UE2 can perform measurement by changing the receiving beam for the same beam, and based on this, information about the transmit / receive beam pair for UE1 and UE2 can be obtained.

[0101] In the example of Fig. 10, 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, the UE can measure multiple UE1 TX beams within a single SL slot. In this case, identifier information can be transmitted via the SCI of the PSCCH, the PSSCH, or the MAC-CE.

[0102] The disclosures proposed in this specification and the examples of FIGS. 7A to 10 can be operated in a simple expanded, modified, or combined form.

[0103] Below, a description is given of a device to which this specification can be applied.

[0104] FIG. 11 illustrates a wireless communication device according to one embodiment of the present specification.

[0105] Referring to FIG. 11, a wireless communication system may include a first device (100) and a second device (200).

[0106] 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.

[0107] 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.

[0108] 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.

[0109] 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.

[0110] 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.

[0111] 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.

[0112] Although the preferred embodiments have been described above by way of example, the disclosure of this specification is not limited to such 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 reference signal (RS) for beam pairing; A step of receiving beam reporting based on the above transmitted reference signal; A step of transmitting a direct link establishment request (DCR) message based on the received beam reporting; and A method comprising the step of receiving a direct link establishment accept (DCA) message in response to the transmitted direct link establishment request.

2. In paragraph 1, A method wherein the above direct link establishment request message includes a beam pairing response.

3. In paragraph 1, A method in which the above direct link establishment request message is transmitted based on a specific time offset.

4. 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).

5. In paragraph 1, A method wherein the above reference signal includes identifier information of the transmitting terminal and / or the receiving terminal.

6. In a method for a receiving terminal to perform sidelink communication, A step of receiving a reference signal (RS) for beam pairing; A step of transmitting beam reporting based on the received reference signal; A step of receiving a direct link establishment request (DCR) message based on the transmitted beam reporting; and A method comprising the step of transmitting a direct link establishment accept (DCA) message in response to the received direct link establishment request.

7. In paragraph 6, A method wherein the above direct link establishment request message includes a beam pairing response.

8. In paragraph 6, A method in which the above direct link establishment request message is received based on a specific time offset.

9. In paragraph 6, 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).

10. In paragraph 6, A method wherein the above reference signal includes identifier information of the transmitting terminal and / or the receiving terminal.

11. 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 of transmitting a reference signal (RS) for beam pairing, A step of receiving beam reporting based on the above-mentioned transmitted reference signal, A step of transmitting a direct link establishment request (DCR) message based on the received beam reporting, and A transmitting terminal, comprising a step of receiving a direct link establishment accept (DCA) message in response to the transmitted direct link establishment request.

12. In paragraph 11, The above direct link setup request message includes a beam pairing response, the transmitting terminal.

13. In paragraph 11, The above direct link setup request message is transmitted based on a specific time offset, the transmitting terminal.

14. In paragraph 11, A transmitting terminal, 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).

15. In paragraph 11, A transmitting terminal, wherein the reference signal includes identifier information of the transmitting terminal and / or the receiving terminal.

16. 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 of receiving a reference signal (RS) for beam pairing, A step of transmitting beam reporting based on the received reference signal, A step of receiving a direct link establishment request (DCR) message based on the transmitted beam reporting, and A receiving terminal comprising a step of transmitting a direct link establishment accept (DCA) message in response to the received direct link establishment request.

17. In paragraph 16, The receiving terminal, wherein the above direct link establishment request message includes a beam pairing response.

18. In paragraph 16, The above direct link setup request message is received by the receiving terminal based on a specific time offset.

19. In paragraph 16, A receiving terminal, 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).

20. In paragraph 16, A receiving terminal, wherein the above reference signal includes identifier information of the transmitting terminal and / or the receiving terminal.

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