KR102604254B1 - Method and apparatus for performing synchronization procedure in new radio vehicle to everything system - Google Patents

Abstract

The present invention can provide a method for a terminal to perform a synchronization procedure in the NR V2X system. At this time, the method of performing the synchronization procedure includes determining whether the frequency for V2X sidelink communication of the terminal is within the coverage on the network, and selecting a synchronization reference source based on whether the frequency is within the coverage on the network. can do.

Description

Method and device for performing synchronization procedure for NR V2X system {METHOD AND APPARATUS FOR PERFORMING SYNCHRONIZATION PROCEDURE IN NEW RADIO VEHICLE TO EVERYTHING SYSTEM}

The present invention relates to a method and synchronization procedure for transmitting and receiving synchronization signals for a New Radio (NR) Vehicle To Everything (V2X) system.

The International Telecommunication Union (ITU) is developing the International Mobile Telecommunication (IMT) framework and standards, and is currently discussing 5th generation (5G) communications through a program called “IMT for 2020 and beyond.” .

In order to meet the requirements presented by "IMT for 2020 and beyond", the 3rd Generation Partnership Project (3GPP) NR (New Radio) system takes into account various scenarios, service requirements, potential system compatibility, etc., and provides time-frequency Discussions are underway to support various numerologies for resource unit standards.

Additionally, V2X communication refers to a communication method that exchanges or shares information such as traffic conditions while communicating with road infrastructure and other vehicles while driving. V2X refers to V2V (vehicle-to-vehicle), which refers to LTE (Long Term Evolution)-based communication between vehicles, V2P (vehicle-to-pedestrian), which refers to LTE-based communication between vehicles and terminals carried by individuals, and vehicle and V2I/N (vehicle-to-infrastructure/network), which refers to LTE-based communication between units/networks on the roadside. Here, a roadside unit (RSU) may be a transportation infrastructure entity implemented by a base station or a fixed terminal. For example, it could be an entity that sends speed notifications to a vehicle.

The present invention can provide a method of performing a synchronization procedure in the NR V2X system.

The present invention can provide a method of selecting a synchronization reference source based on whether the NR V2X sidelink frequency of the NR V2X sidelink (SL) terminal is included in the coverage on the network.

The present invention can provide a method of selecting a synchronous reference source when the NR V2X sidelink frequency is in-coverage (IC).

The present invention can provide a method for selecting a synchronous reference source when the NR V2X sidelink frequency is out-of-coverage (OCC).

The present invention can provide a method for a terminal to perform a synchronization procedure in the NR V2X system. At this time, the method of performing the synchronization procedure includes determining whether the frequency for V2X sidelink communication of the terminal is within the coverage on the network, and selecting a synchronization reference source based on whether the frequency is within the coverage on the network. can do.

According to the present disclosure, a method of performing a synchronization procedure in the NR V2X system can be provided.

According to the present disclosure, a method of selecting a synchronization reference source can be provided based on whether the NR V2X sidelink frequency of the NR V2X sidelink terminal is included in the coverage on the network.

According to the present disclosure, when the NR V2X sidelink frequency is incoverage, a method for selecting a synchronization reference source can be provided.

According to the present disclosure, when the NR V2X sidelink frequency is out of coverage, a method for selecting a synchronization reference source can be provided.

The effects that can be obtained from the present disclosure are not limited to the effects mentioned above, and other effects not mentioned can be clearly understood by those skilled in the art from the description below. will be.

Figure 1 is a diagram showing a frame structure for downlink/uplink transmission to which the present disclosure can be applied.
Figure 2 is a diagram showing a resource grid and resource block to which the present disclosure can be applied.
Figure 3 is a diagram showing a method of transmitting a synchronization signal according to an embodiment of the present invention.
Figure 4 is a diagram showing the system architecture according to an embodiment of the present invention.
Figure 5 is a diagram showing a method of transmitting a synchronization signal.
Figure 6 is a diagram showing a scenario in which NR V2X sidelink communication is performed in a 3GPP network.
Figure 7 is a diagram showing a method of selecting a synchronous reference source in coverage.
Figure 8 is a diagram showing a method of selecting a synchronous reference source in out-of-coverage.
Figure 9 is a diagram showing the configuration of a base station device and a terminal device according to the present disclosure.

Hereinafter, with reference to the attached drawings, embodiments of the present disclosure will be described in detail so that those skilled in the art can easily practice them. However, the present disclosure may be implemented in many different forms and is not limited to the embodiments described herein.

In describing embodiments of the present disclosure, if it is determined that detailed descriptions of known configurations or functions may obscure the gist of the present disclosure, detailed descriptions thereof will be omitted. In addition, in the drawings, parts that are not related to the description of the present disclosure are omitted, and similar parts are given similar reference numerals.

In the present disclosure, when a component is said to be “connected,” “coupled,” or “connected” to another component, this is not only a direct connection relationship, but also an indirect connection relationship in which another component exists in between. It may also be included. In addition, when a component is said to "include" or "have" another component, this does not mean excluding the other component, but may further include another component, unless specifically stated to the contrary. .

In the present disclosure, terms such as first, second, etc. are used only for the purpose of distinguishing one component from other components, and do not limit the order or importance of components unless specifically mentioned. Accordingly, within the scope of the present disclosure, a first component in one embodiment may be referred to as a second component in another embodiment, and similarly, the second component in one embodiment may be referred to as a first component in another embodiment. It may also be called.

In the present disclosure, distinct components are intended to clearly explain each feature, and do not necessarily mean that the components are separated. That is, a plurality of components may be integrated to form one hardware or software unit, or one component may be distributed to form a plurality of hardware or software units. Accordingly, even if not specifically mentioned, such integrated or distributed embodiments are also included in the scope of the present disclosure.

In the present disclosure, components described in various embodiments do not necessarily mean essential components, and some may be optional components. Accordingly, embodiments consisting of a subset of the elements described in one embodiment are also included in the scope of the present disclosure. Additionally, embodiments that include other components in addition to the components described in the various embodiments are also included in the scope of the present disclosure.

In addition, this specification describes a wireless communication network, and work performed in the wireless communication network is performed in the process of controlling the network and transmitting data in a system (for example, a base station) in charge of the wireless communication network, or in the process of controlling the network and transmitting data. Work can be performed on a terminal connected to the network.

That is, it is obvious that in a network comprised of a plurality of network nodes including a base station, various operations performed for communication with a terminal can be performed by the base station or other network nodes other than the base station. 'Base Station (BS)' can be replaced by terms such as fixed station, Node B, eNode B (eNB), and Access Point (AP). In addition, 'terminal' can be replaced by terms such as UE (User Equipment), MS (Mobile Station), MSS (Mobile Subscriber Station), SS (Subscriber Station), and non-AP station (non-AP STA). You can.

In the present disclosure, transmitting or receiving a channel includes transmitting or receiving information or signals through the channel. For example, transmitting a control channel means transmitting control information or signals through the control channel. Similarly, transmitting a data channel means transmitting data information or signals through a data channel.

In the following description, the term NR system is used for the purpose of distinguishing the system to which various examples of the present disclosure are applied from existing systems, but the scope of the present disclosure is not limited by this term. In addition, the term NR system in this specification is used as an example of a wireless communication system that can support various subcarrier spacing (SCS), but the term NR system itself refers to a wireless communication system that supports multiple SCS. It is not limited.

Figure 1 is a diagram showing the NR frame structure and numerology, according to an embodiment of the present invention.

The basic unit of time domain in NR is It can be. At this time, ego, It can be. also, May be a constant for the multiple relationship between the NR time unit and the LTE time unit. In LTE as a reference time unit, , and can be defined.

frame structure

Referring to Figure 1, the time structure of the frame for downlink and uplink (Downlink/Uplink, DL/UL) transmission is You can have At this time, one frame is It consists of 10 subframes corresponding to time. The number of consecutive OFDM symbols per subframe is It can be. Additionally, each frame is divided into two half frames, and a half frame may consist of 0 to 4 subframes and 5 to 9 subframes. At this time, half frame 1 may be composed of 0 to 4 subframes, and half frame 2 may be composed of 5 to 9 subframes.

At this time, the transmission timing of the uplink transmission frame i is determined based on Equation 1 below based on the downlink reception timing at the terminal.

In Equation 1 below: may be a TA offset value that occurs due to duplex mode differences, etc. Basically in FDD (Frequency Division Duplex) has 0, but in TDD (Time Division Duplex), considering the margin for DL-UL switching time, It can be defined as a fixed value.

[Equation 1]

Figure 2 is a diagram showing a resource grid and a resource block.

Referring to FIG. 2, resource elements in the resource grid may be indexed according to each subcarrier spacing. At this time, one resource grid can be created for each antenna port and for each subcarrier spacing. Uplink and downlink transmission and reception can be performed based on the corresponding resource grid.

One resource block is composed of 12 resource elements in the frequency domain, and an index for one resource block for each 12 resource elements as shown in Equation 2 below ( ) can be configured. Indexes for resource blocks can be utilized within a specific frequency band or system bandwidth.

[Equation 2]

Numerologies

Numerology can be configured in various ways to satisfy the various services and requirements of the NR system. At this time, referring to Table 1 below, the numerology can be defined based on the subcarrier spacing (SCS), CP length, and number of OFDM symbols per slot used in the OFDM (Orthogonal Frequency Division Multiplexing) system. . The above-described values can be provided to the terminal through upper layer parameters DL-BWP-mu and DL-BWP-cp (DL) and UL-BWP-mu and UL-BWP-cp (UL).

Additionally, as an example, in Table 1 below When is 2, when subcarrier spacing is 60kHz, normal CP and extended CP (Extended CP) can be applied, and only normal CP can be applied in other bands.

[Table 1]

At this time, normal slot can be defined as a basic time unit used to transmit one piece of data and control information in the NR system. The length of the normal slot can basically be configured as the number of 14 OFDM symbols. Additionally, unlike slots, subframes have an absolute time length equivalent to 1 ms in the NR system and can be used as a reference time for the length of other time sections. At this time, for coexistence or backward compatibility between LTE and NR systems, a time interval such as a subframe of LTE may be required in the NR standard.

For example, in LTE, data may be transmitted based on a unit of time, Transmission Time Interval (TTI), and the TTI may be composed of one or more subframes. At this time, even in LTE, one subframe may be set to 1ms and may include 14 OFDM symbols (or 12 OFDM symbols).

Additionally, non-slot may be defined in NR. A non-slot may mean a slot with a number that is at least one symbol smaller than a normal slot. For example, when providing low latency, such as a URLLC (Ultra-Reliable and Low Latency Communications) service, latency can be reduced through a non-slot with a smaller number of symbols than a normal slot. At this time, the number of OFDM symbols included in the non-slot can be determined considering the frequency range. For example, in the frequency range of 6 GHz or higher, a non-slot with a length of 1 OFDM symbol may be considered. As another example, the number of OFDM symbols defining a non-slot may include at least two OFDM symbols. At this time, the range of the number of OFDM symbols included in the non-slot can be configured as the length of the mini slot up to the normal slot length - 1. However, as a non-slot standard, the number of OFDM symbols may be limited to 2, 4, or 7 symbols, but is not limited to the above-described embodiment.

Additionally, as an example, in the unlicensed band below 6 GHz, Subcarrier spacing corresponding to 1 and 2 is used, and in unlicensed bands above 6 GHz, Subcarrier spacing corresponding to 3 and 4 may be used. At this time, as an example, When is 4, it can be used only for SSB (Synchronization Signal Block), which will be described later, and is not limited to the above-described embodiment.

In addition, Table 2 shows the information for each subcarrier spacing setting in the case of normal CP. Number of OFDM symbols per slot represents. Table 2 shows the number of OFDM symbols per slot, the number of slots per frame, and the number of slots per subframe according to each subcarrier spacing value as provided in Table 1. At this time, Table 2 shows the above-described values based on a normal slot with 14 OFDM symbols.

[Table 2]

Additionally, as described above, In the case where is 2, extended CP can be applied when subcarrier spacing is 60 kHz. Table 3 shows the case of extended CP. Number of OFDM symbols per slot Each value can be expressed based on a normal slot of 12. At this time, referring to Table 3, in the case of an extended CP following 60 kHz subcarrier spacing, the number of symbols per slot, the number of slots per frame, and the number of slots per subframe can be indicated.

[Table 3]

Next, the structure of SSB/PBCH (Physical Broadcast Channel) in the NR system and the initial cell access procedure in the NR system are described.

At this time, the NR base station (i.e. gNB) may periodically transmit signals and channels as shown in Table 4 below to the terminals in the cell to allow initial cell selection of the terminals (i.e. UEs) within the cell.

[Table 4]

As an example, the SS/PBCH block may be the SSB described above. At this time, in order for a terminal to perform initial wireless access in the NR system, it may be necessary to receive a synchronization signal transmitted from the wireless access system and a broadcast channel that carries important system information. To this end, the terminal can check the reception sensitivity of the synchronization signal to find the optimal cell in the best channel environment. The terminal may perform frequency/time synchronization and cell identification operations for initial access to the optimal channel among one or more channels within a specific frequency band operated based on the checked reception sensitivity. The terminal can check the boundary of the OFDM symbol timing through the above-described operation and then start decoding the PBCH within the same SSB.

At this time, the terminal can perform PBCH decoding by receiving the PBCH Demodulation Reference Signal (DMRS). Additionally, the terminal can obtain 2 or 3 LSB bit information among the SSB index information bits through PBCH DMRS. Afterwards, the terminal can perform PBCH decoding to obtain information included in the PBCH payload. Afterwards, the terminal can perform the decoding procedure of SIB 1 using the information obtained through the PBCH.

For example, in the NR system, the terminal may receive Remaining System Information (RMSI) as system information not transmitted on the PBCH through a broadcast signal or channel. Additionally, the terminal can receive Other System Information (OSI) and Paging Channel as additional system information through a broadcast signal or channel.

Afterwards, the terminal can connect to the base station through the RACH (Random Access Channel) procedure and then perform mobility management.

Also, as an example, when the terminal receives SSB, there is a need to set SSB Composition and SS Burst Set Composition.

NR V2X Service

Regarding V2X services, existing V2X services (e.g. LTE Rel-14 V2X) were able to support a set of basic requirements for V2X services. At this time, the requirements were basically designed with thorough consideration of road safety service. Therefore, V2X UEs (User Equipment) can exchange self-state information through sidelinks and exchange the above-mentioned information with infrastructure nodes and/or pedestrians. It became possible.

Meanwhile, in a more advanced V2X service (e.g. LTE Rel-15), carrier aggregation, high order modulation, latency reduction, and transmission diversity (Tx) within the sidelink are implemented. New features were introduced considering diversity and feasibility of sTTI. Based on the above, coexistence (same resource pool) with V2X UEs was required, and the above-mentioned services were provided based on LTE.

As an example, considering use cases for supporting new V2X services as SA (System Aspect) 1, technical features can be broadly classified based on four categories as shown in Table 5 below. At this time, in Table 5 below, vehicle platooning may be a technology in which a plurality of vehicles dynamically form a group and operate similarly. Additionally, Extended Sensors may be a technology that collects and exchanges data obtained from sensors or video images. Additionally, advanced driving may be a technology in which a vehicle is driven based on full automation or semi-automation. Additionally, remote driving may be a technology that provides technology and applications for remote control of a vehicle, and more detailed information regarding the above may be shown in Table 5 below.

[Table 5]

In addition, the above-described SA1 can be considered both LTE and NR as an eV2X (enhanced V2X) support technology to support new V2X services. As an example, the NR V2X system may be the first V2X system. Additionally, the LTE V2X system may be a second V2X system. In other words, the NR V2X system and the LTE V2X system may be different V2X systems. In the following, related content is described based on the method for satisfying the low delay and high reliability required in NR sidelink based on the NR V2X system. However, the same or similar configuration can be expanded and applied to the LTE V2X system, and is not limited to the examples below. In other words, it can be applied to the LTE V2X system to parts that can operate interoperably, and is not limited to the examples below. At this time, as an example, NR V2X capability may not necessarily be limited to supporting only V2X services, and which V2X RaT to use may be selected.

Figure 3 is a diagram showing a method for transmitting sidelink synchronization information.

Referring to FIG. 3, sidelink synchronization information may be transmitted. At this time, as an example, Figure 3(a) may be a method of transmitting synchronization information of the first V2X system (or LTE V2X system). Additionally, Figure 3(b) may be a method of transmitting synchronization information of the second V2X system (or NR V2X system).

Referring to FIG. 3(a), signaling for synchronization information transmission of the LTE sidelink for V2X can be considered in coverage (IC) or partial coverage. At this time, the description below is based on the IC case, and the same can be applied to the case of partial coverage, and is not limited to the above-described embodiment.

Additionally, signaling for synchronization information transmission of the LTE sidelink may be considered out of coverage (OOC). At this time, as an example, in the case of IC, the terminal 301 may receive configuration information for synchronization signal transmission from the base station 302 (EUTRAN) through SIB (System Information Block) 18 and/or SIB 21. Additionally, as an example, when the terminal 303 is in an RRC Connected state, configuration information for synchronization signal transmission may be transmitted through an RRC connection message. At this time, the terminal may transmit synchronization information to another terminal through SLSS & Master Information Block-SL and/or Master Information Block-SL-V2X based on the configuration information. Through this, synchronization information of the side link can be transmitted.

Meanwhile, in the case of OOC, the terminal 303 can provide synchronization information to another terminal 304 by including synchronization information in SLSS & Master Information Block-SL and/or Master Information Block-SL-V2X, as described above. It is not limited to examples.

Additionally, as an example, referring to FIG. 3(b), in the case of an IC, as a second V2X system (NR V2X system), the terminal 305 receives a synchronization signal from the base station 306 (NR) through OSI (Other System Information). Setting information for transmission can be obtained. Additionally, as an example, when the terminal 305 is in an RRC connection state, configuration information for synchronization signal transmission may be transmitted through an RRC connection message. At this time, the terminal 305 may include synchronization information in the NR SLSS and/or NR V2X MIB and transmit it to another terminal through the sidelink.

Meanwhile, in the case of OOC, the terminal 307 may provide synchronization information to another terminal 308 by including synchronization information in the NR SLSS and/or NR V2X MIB, and is not limited to the above-described embodiment.

In addition, as an example, in the second V2X system (NR V2X system), similar to Figure 3 (a), in the case of IC, the terminal 309 transmits configuration information for synchronization signal transmission from the base station 310 (EUTRAN) through SIB 21. can receive. Additionally, as an example, when the terminal 309 is in an RRC Connected state, configuration information for synchronization signal transmission may be transmitted through an RRC connection message. At this time, the terminal can transmit synchronization information to another terminal through Master Information Block-SL-V2X based on the configuration information. Through this, synchronization information of the side link can be transmitted.

Meanwhile, in the case of OOC in the second V2X system (NR V2X system), the terminal 311 may provide synchronization information to the other terminal 312 by including synchronization information in the NR SLSS and/or NR V2X MIB, as described above. It is not limited to one embodiment.

That is, in the case of IC, the V2X terminal receives system information as previously described for sidelink synchronization (SL synchronization) transmission from the network based on the LTE/NR Uu link (link between eNB or gNB and the terminal). Settings can be provided based on this. At this time, as described above, methods for transmitting synchronization information on the sidelink include network signaling-based transmission and terminal-based transmission. At this time, the terminal can receive a synchronization signal and system configuration information for V2X-MIB transmission from the LTE and/or NR base station and perform NR SL-SSB transmission based on it. At this time, if the terminal is connected to the LTE cell and/or NR cell in RRC connected mode, system configuration information is provided to the terminal through an RRC reset message, and the terminal can perform NR SL-SSB transmission based on the information. .

Meanwhile, in the case of terminal-based transmission, in the case of IC, the terminal can receive information through a broadcasting signal (e.g. System information) from the base station. Alternatively, in the case of OOC, it is possible to determine whether to transmit synchronization information based on a preset threshold, and is not limited to the above-described embodiment.

Based on the above, synchronization information transmitted by the terminal can be obtained by the IC based on signals and information received from the base station. Additionally, as an example, synchronization information transmitted by the terminal may be obtained from another sidelink transmitting terminal. Additionally, as an example, synchronization information transmitted by the terminal may be derived based on signals and information received from GNSS.

In the following, a terminal that generates synchronization information on its own and transmits synchronization information is referred to as a synchronization reference terminal (i.e. SyncRef UE). That is, the terminal can generate synchronization information on its own based on the acquired information and transmit it to other terminals, as described above. At this time, as an example, in the case of OOC, NR-SSB transmission may be performed based on SLSS and MIB information provided from the synchronization reference terminal, and this may be to provide advance information for transmitting synchronization information to the terminal.

In the following, a synchronization signal transmission method and synchronization procedure will be described based on the above. At this time, as an example, the NR Sidelink Frequency may consider FR1, a frequency below 6 GHz, and FR2 (i.e. up to 52.6 GHz), a frequency above 6 GHz. Additionally, as an example, both unlicensed ITS bands and licensed bands may be considered for the NR sidelink frequency. That is, as described above, a common design method may be needed to support each frequency band. To this end, NR sidelink design considering the NR system may be necessary. For example, even if it is an omni-directional Tx/Rx that is not actually beam-based, as in the NR standard design, an NR sidelink design that can basically support beam-based transmission and reception may be necessary, and is not limited to the above. . In addition, Table 6 below may represent each term applied in the following invention, but is not limited to the above-described examples.

[Table 6]

NR side link design

Below, we describe the NR V2X sidelink design method that satisfies the requirements for the advanced V2X (i.e. eV2X) services described above.

More specifically, the synchronization procedures and methods required to form a radio link for the NR sidelink are described in detail. For example, as described above, in the NR side link design, FR1 and FR2 (i.e. up to 52.6 GHz) as NR side link frequencies and unlicensed ITS bands and licensed bands ITS are the frequency bands in which the NR system operates. and range can all be considered. Additionally, as an example, the availability of the LTE (NG-eNB)/NR Uu link, which is a 3GPP NG-RAN network in Table 6 described above, can be considered in the NR sidelink design.

Additionally, as an example, a design for transmitting and receiving eV2X synchronous information and signals to satisfy higher requirements from the advanced V2X services described above may be considered. At this time, the frequency for NR V2X sidelink communication is different from the existing system (e.g. LTE), and at least one or more of the factors shown in Table 7 below can be further considered based on the technologies required in the new system. In other words, there is a need to satisfy new V2X service requirements by applying NR V2X side link based on NR wireless access technology, especially uplink transmission-related technologies, as shown in Table 7 below.

Additionally, other factors may be considered in consideration of the new system in addition to Table 7 below, and are not limited to the above-described embodiments.

[Table 7]

Additionally, as an example, the physical channel, signal, basic slot structure, and physical resources of the NR V2X sidelink may be as shown in Table 8 below.

[Table 8]

Additionally, as an example, Figure 4 may be a basic network architecture configuration considering NR V2X sidelink.

As an example, referring to Figure 4, 5GC (5G Core NW) nodes (410-1, 410-2) and NG-RAN nodes (420-1, 420-2, 430-1, 430-2) An NG interface can be set up between them. Additionally, an Xn interface may be set between the NG-RAN nodes (420-1, 420-2, 430-1, and 430-2). At this time, in the above-described architecture, gNB (NR UP/CP protocol, 420-1, 420-2) and NG-eNB (E-UTRA UP/CP protocol, 430-1, 430-2) that constitute NG-RAN Centrally, the nodes can be interconnected through the Xn interface. Additionally, as described above, 5GC can be connected to the NG interface. At this time, as an example, in the above-described architecture, both the LTE sidelink terminal and the NR sidelink terminal can be controlled by NG-RAN (i.e. LTE Uu and NR Uu) based on gNB and NG-eNB. Therefore, when the NR sidelink terminal transmits synchronization information, it can receive synchronization information from the LTE Uu or NR Uu link and transmit NR sidelink synchronization information (e.g. SL Synchronization Signal/SL Physical broadcast Channel) based on the information. It is not limited to the above-described embodiments. That is, the NR sidelink terminal can obtain synchronization information not only through the NR Uu link but also through the LTE Uu link.

Meanwhile, in relation to V2X side link communication, V2X side link terminals can perform V2X side link communication. However, in order for V2X sidelink terminals to start communication, certain conditions need to be satisfied, and the conditions may be as shown in Table 9 below. In other words, the V2X sidelink terminal can perform V2X sidelink communication in RRC idle state, inactive state, or connected mode. In addition, V2X sidelink terminals that perform V2X sidelink communication need to be registered in a cell selected on the frequency used or belong to the same PLMN. In addition, if the V2X sidelink terminal is OOC on the frequency for V2X sidelink communication, V2X sidelink communication can be performed only if V2X sidelink communication can be performed based on pre-configuration information. .

[Table 9]

At this time, as described above, sidelink synchronization information may be required to start V2X sidelink communication. Therefore, the terminal needs to transmit sidelink synchronization information. However, the transmitting terminal (Sidelink Tx UE) may receive settings for transmitting sidelink synchronization information before transmitting the corresponding synchronization information. At this time, as an example, the transmitting terminal may receive settings for transmitting sidelink synchronization information based on a system information message or an RRC reset message (in the case of RRC CONNECTED UE) broadcast from the above-described NG-RAN nodes. Also, as an example, if an NR V2X sidelink terminal (hereinafter referred to as a terminal) does not exist in the NG-RAN network, sidelink synchronization information can be transmitted based on preset information, as described above.

At this time, terminals capable of NR V2X sidelink communication can perform SLSS/PSBCH transmission first. As an example, Figure 5 is a diagram showing a method for a transmitting terminal to transmit SLSS/PSBCH.

More specifically, referring to FIG. 5, the transmitting terminal can receive settings for synchronization information as described above. (S510) At this time, as described above, settings for synchronization information may be received through system information or RRC reset messages broadcast from NG-RAN nodes. Additionally, as an example, preset information may be used, as described above. At this time, the terminal may determine synchronization information to transmit based on information received from the base station or preset information. For example, through system information such as SIB21/OSI, the LTE/NR base station can provide the terminal with configuration information for transmitting synchronization information, as described above. Additionally, if the terminal is not provided with the above-described information, it can subsequently perform SLSS/PSBCH transmission based on preset information.

Next, initialization can be performed. (S520) At this time, the terminal can check whether the frequency for V2X sidelink communication is within in-coverage. Additionally, the terminal can check whether it has selected a synchronization reference for GNSS or a synchronization reference for a cell as a synchronization reference. Additionally, the terminal can check whether the network is in a mode that controls synchronization signal transmission. At this time, for example, whether to transmit SLSS/PSBCH and the transmission method may be determined depending on whether the network is in a mode that controls synchronization signal transmission.

Next, the transmitting terminal can perform SLSS/PSBCH transmission. (S530) At this time, the transmitting terminal can decide whether to transmit and the transmission method for the SLSS/PSBCH based on the information determined in the initialization step, which will be described later. In the following, procedures and methods for synchronous reference selection/reselection of SLSS/PSBCH transmission for NR V2X sidelink communication are described based on the above.

Embodiment (Source selection/reselection method of synchronous reference for NR V2X SLSS/PSBCH block transmission)

Based on the above, the terminal can determine the source for the synchronization reference. At this time, the terminal may first need to determine the resource corresponding to the slot or time domain in which the SLSSID (Sidelink SSID) and NR SL SSB (Sidelink Synchronization Signal Block) are transmitted. Additionally, as an example, the terminal can select the numerology (e.g. SCS) to be used. At this time, as an example, the parameters of the above-described numerology may be set through control of the base station. Additionally, as an example, one numerology may be arbitrarily determined in advance depending on the frequency used by V2X sidelink communication, and is not limited to the above-described embodiment. Additionally, as an example, the terminal may determine other additional information in advance before determining the source for synchronization reference, and is not limited to the above-described embodiment.

Meanwhile, Figure 6 may be an example of a scenario in which NR V2X sidelink communication is performed in a 3GPP network based on the above-mentioned. At this time, NR V2X sidelink communication may be performed on a 3GPP network (hereinafter referred to as NG-RAN), and the presence of GNSS signals may be additionally considered.

More specifically, referring to FIG. 6, each NR V2X sidelink terminal may be IC or OOC based on the NG-eNB (610). Additionally, it may be IC or OOC based on the gNB 620. Additionally, it may be IC or OOC based on the GNSS 630. At this time, considering the above-mentioned situation, NR V2X sidelink terminals can select the source of synchronization reference based on the location and capabilities of the terminal, which will be described later. Additionally, as an example, in addition to the scenario shown in FIG. 6, scenarios shown in Table 10 below may be considered, and are not limited to the above-described embodiment.

[Table 10]

Example 1 (when the frequency for V2X sidelink communication of the NR V2X sidelink terminal is coverage (IC) on a 3GPP network corresponding to LTE/NR)

A case where the terminal for which V2X sidelink communication is triggered may have an IC frequency for V2X sidelink communication may be considered. At this time, as an example, if the frequency for V2X sidelink communication is IC, it may mean that it is within the coverage of at least one 3GPP network (e.g. LTE cell or NR cell).

Additionally, as an example, a terminal for which V2X sidelink communication is triggered transmits an RRC reset message from at least one 3GPP network (e.g. LTE cell or NR cell) or on the associated serving cell/PCell, although the frequency for V2X sidelink communication is OOC. If the frequency for the V2X communication is included in the “v2x-InterFreqInfoList” in the system information, the method below can be applied in the same way as in the case of IC. At this time, as an example, in the case of OOC, the frequency for V2X sidelink communication may not be included in the coverage of all 3GPP networks (e.g. LTE cell or NR cell). However, as described above, the frequency for the V2X communication is included in the “v2x-InterFreqInfoList” as the UE transmits an RRC reset message or system information transmitted on the associated serving cell/PCell, and the system information containing this is included in the RRC reset message or Even when transmitted on the associated serving cell/PCell, the terminal can operate the same as in the case of encoverage.

At this time, the terminal can select the source of synchronization reference based on the parameter for the synchronization type in the system information provided by the 3GPP network. For example, if the parameter for the synchronization type in the system information provided by the 3GPP network is “NR”, the terminal can select the NR cell as the source of synchronization reference.

On the other hand, if the parameter for the synchronization type in the system information provided by the 3GPP network is “eNB”, the terminal can select an LTE cell as the source of synchronization reference.

Additionally, if the parameter for synchronization type in the system information provided by the 3GPP network is “GNSS”, the terminal can select a GNSS cell as the source of synchronization reference. That is, the source of the synchronization reference can be determined based on the parameter for the synchronization type in the system information provided by the 3GPP network.

At this time, as an example, parameters related to the synchronization type in the system information of each LTE/NR 3GPP network may not be aligned. Even at this time, the terminal needs to determine the source of the synchronization reference, and a selection method for this may be necessary.

As an example, the UE may not expect to receive signaling for different synchronization type values from an LTE/NR cell. At this time, the terminal can ignore the signaling provided by the 3GPP network for the synchronization type and perform the same operation as the case below where the synchronization type parameter is not provided or set, which will be described later.

As another example, the terminal may receive different synchronization type information from an LTE/NR cell. At this time, the terminal can be set to preferentially follow either LTE or NR system information and select a synchronization reference source based on the prioritized system information.

Additionally, as an example, a case where the terminal is not provided with parameters for the synchronization reference source may be considered. At this time, the terminal can decide whether to select GNSS as the source of synchronization reference based on the reliability of the GNSS signal. More specifically, if the terminal is not provided with parameters for the synchronization reference source, the terminal can determine the reliability of the GNSS signal. At this time, reliability may be the signal strength of the GNSS signal as a threshold value. In other words, if the signal strength of the GNSS signal is greater than the threshold value, it can be determined that the reliability of the signal is satisfied. Additionally, as an example, in measuring reliability, if the timing error value is less than or equal to a threshold (e.g. 12*Ts, where Ts is the LTE/NR minimum time unit), it can be determined that reliability is satisfied. Additionally, as an example, when measuring reliability, if the frequency error value is less than or equal to a threshold (e.g. ±0.1PPM), it can be determined that reliability is satisfied. Of course, it is not limited to the above-described embodiment. At this time, if reliability is satisfied based on the above, the terminal can select GNSS as the source of synchronization reference.

On the other hand, if the UE is not provided with parameters for the synchronization reference source, the case where GNSS reliability does not meet certain standards can be considered. At this time, the terminal may not select GNSS as the source of synchronization reference. As an example, the terminal may detect an SLSS signal with a specific SLSSID value (e.g. SLSSID=0) corresponding to GNSS timing on the frequency for V2X sidelink communication. At this time, when the terminal detects the corresponding SLSS signal, if the SLSS/PSBCH block RSRP value evaluated after L3 filtering in the corresponding SLSS is higher than the minimum standard for satisfying reliability, the terminal uses the corresponding SLSS as a reference synchronization to use the synchronization reference terminal ( SyncRef UE) can be selected. Here, the L3 filtering refers to the operation of collecting samples of RSRP values received from the physical layer at Layer 3 (e.g. RRC layer) over a certain period of time and deriving one value through cumulative weight averaging calculation. That is, if the SLSS transmitted by another terminal that has received the GNSS timing is detected and reliability is satisfied as described above, the terminal can select the terminal that transmitted it as the synchronization reference terminal.

However, the terminal may not be able to detect an SLSS signal with a specific SLSSID value (e.g. SLSSID=0) corresponding to the GNSS timing. That is, the terminal may not be able to receive SLSS transmitted from a terminal that directly receives GNSS timing. At this time, the terminal can select one value among the timings of the LTE/NR cell corresponding to the 3GPP network, and at least one of the following embodiments can be selected.

Example 1-1 (based on serving cell)

As described above, when the terminal is not provided with parameters for the synchronization reference source and does not satisfy GNSS reliability, a SLSS signal with a specific SLSSID value (e.g. SLSSID = 0) corresponding to the GNSS timing cannot be detected. , the terminal can select a synchronous reference based on the serving cell. For example, the serving cell reference may mean a cell that receives system information through a serving cell, primary frequency, secondary frequency, PCell, or SCell. That is, the terminal can select a synchronization reference source based on the cell receiving system information. At this time, as an example, the terminal may determine whether it is an LTE serving cell or an NR serving cell based on the source from which it received the system information.

At this time, if the configuration information related to the frequency for V2X sidelink communication is set, provided, or associated with an LTE cell (LTE serving cell, PCell or SCell), the terminal uses the LTE cell timing as a reference source. You can choose. On the other hand, if the terminal has configuration information related to the frequency for V2X sidelink communication set, provided, or associated with an NR cell (NR serving cell, PCell or SCell), the terminal uses the NR cell timing as a reference source. You can choose. That is, the terminal can select the timing of a cell in which configuration information related to the frequency for V2X sidelink communication is set as a serving cell for receiving system information as a reference source.

Example 1-2 (based on DL RSRP intensity)

As described above, when the terminal is not provided with parameters for the synchronization reference source and does not satisfy GNSS reliability, a SLSS signal with a specific SLSSID value (e.g. SLSSID = 0) corresponding to the GNSS timing cannot be detected. , the terminal can select a synchronous reference based on downlink RSRP (Downlink Received Signal Received Power, DL RSRP).

At this time, as an example, if the DL RSRP value from an LTE cell related to the frequency for V2X sidelink communication is greater than a specific reference value set, the terminal may select the LTE cell timing as a reference source. At this time, the specific reference value may have a certain error as a threshold value.

Additionally, as an example, if the DL RSRP value from an NR cell related to the frequency for V2X sidelink communication is greater than a specific reference value set, the terminal may select the NR cell timing as a reference source.

At this time, as an example, the case of receiving a DL RSRP greater than a specific reference value set from both the LTE cell and the NR cell related to the frequency for V2X sidelink communication described above can be considered. In the case described above, the terminal can compare LTE DL RSRP and NR DL RSRP. At this time, if LTE_RSRP from the LTE cell related to the frequency for V2X sidelink communication is greater than NR_RSRP from the NR cell, the terminal can select the LTE cell timing as a reference source. On the other hand, if LTE_RSRP from an LTE cell related to the frequency for V2X sidelink communication is smaller than NR_RSRP from an NR cell, the terminal can select the NR cell timing as a reference source. That is, if both the DL RSRP of the LTE cell and the DL RSRP of the NR cell are greater than a certain set reference value, the synchronization reference source can be selected based on the greater value by comparing them, as described above.

Example 1-3 (SCS standard)

As described above, when the terminal is not provided with parameters for the synchronization reference source and does not satisfy GNSS reliability, a SLSS signal with a specific SLSSID value (e.g. SLSSID = 0) corresponding to the GNSS timing cannot be detected. , the terminal can select a synchronous reference source based on SCS (Subcarrier spacing). At this time, if the SCS is large, the time resolution may become large. Considering this, if the SCS value from the NR cell associated with the frequency for V2X sidelink communication is greater than LTE, the terminal can select the NR cell timing as a reference source. That is, as described above, if the timing of an NR cell that provides higher time resolution is selected as a synchronization reference source in order to efficiently respond to the higher SCS value that can be utilized in NR V2X side communication, efficient V2X sidelink radio resources Since efficiency can be provided, the terminal can select NR cell timing as a reference source. Meanwhile, if the SCS value from the NR cell associated with the frequency for V2X sidelink communication is the same as LTE, the terminal may select the LTE cell timing as the synchronization reference source.

Example 1-4 (Combination of Examples 1-1 to 1-3)

As another example, a combination of the above-described Examples 1-1 to 1-3 may be considered. As an example, the source for synchronization reference may be determined based on the proposed SCS value as in Example 1-3 described above. That is, Examples 1-3 may have the highest priority. Afterwards, if the SCS values are the same, the synchronization reference signal can be selected based on the cell with the large RSRP value, as in Example 1-2.

In addition, as an example, in Example 1-2, the DL RSRP values of the LTE cell and NR cell are first checked, and if all of the above-mentioned values are greater than the specific reference value set, synchronization is performed based on the serving cell as in Example 1-1. You can set the reference source. That is, Example 1-2 may take precedence over Example 1-1.

In addition, as an example, in Example 1-2, the DL RSRP values of the LTE cell and NR cell are first checked, and if all of the above-mentioned values are greater than the specific reference value set, the serving cell with a large SCS value as in Example 1-3 You can set the synchronous reference source based on . That is, Example 1-2 may take precedence over Example 1-3.

Additionally, as an example, the priorities of Examples 1-1 to 1-3 may be set differently.

Additionally, Figure 7 may be a flowchart based on Examples 1-1 to 1-3 described above.

Referring to Figure 7, the terminal can select a synchronization reference source when the frequency for V2X sidelink communication is in-coverage. (S710) At this time, as described above, when the terminal is provided with parameters for the synchronization reference source. (S720), the terminal can select a synchronous reference source based on the value set in the parameter. (S730) On the other hand, if parameters for the synchronous reference source are not provided, it can be determined whether the reliability of GNSS is satisfied. This is as described above. (S740) At this time, if the reliability of the GNSS is satisfied (S750), the terminal can select the GNSS as the synchronization reference source. On the other hand, if the reliability of the GNSS is not satisfied, it can be checked whether an SLSS signal with a specific SLSSID value corresponding to the GNSS timing can be detected (S760). At this time, when the SLSS signal is detected, the terminal detects the SLSS signal. A synchronous reference source can be selected based on (S770).

On the other hand, if the SLSS signal is not detected, the terminal may select one value among the timing of the LTE cell and the NR cell corresponding to the 3GPP network. (S780) That is, as described above, the terminal may select a value for the synchronization reference source. In the case where parameters are not provided and GNSS reliability is not satisfied and a SLSS signal with a specific SLSSID value (e.g. SLSSID = 0) corresponding to the GNSS timing cannot be detected, the terminal performs the above-described embodiments 1-1 to 1-1. Based on Example 1-4, one value of the timing of the LTE cell and the NR cell corresponding to the 3GPP network can be selected.

Example 2 (when the frequency for V2X sidelink communication of the NR V2X sidelink terminal is out of coverage (OOC) on a 3GPP network corresponding to LTE/NR)

The frequency for V2X sidelink communication of the V2X sidelink terminal may correspond to OOC. At this time, as an example, the terminal may search for all possible slots/symbols and all possible SLSSIDs in the frequency for V2X sidelink communication. In other words, since it is out of coverage on the network, the terminal can first search all possible SLSSIDs in all possible slots/symbols in the frequency for V2X sidelink communication. At this time, if the SLSSID is not detected through the above-described search, the terminal may perform the above-described operation at a frequency for other V2X sidelink communication.

As an example, the terminal may be associated with a different resource pool (e.g. SL-BWP) and the SL-SSB frequency location transmitted on a different frequency. Afterwards, the terminal can calculate the RSRP value of the SLSS corresponding to one or multiple SLSSIDs.

At this time, a case where the UE has never selected both a synchronization reference UE (SyncRef UE) and GNSS as synchronization reference sources can be considered. In other words, the case of performing an initial selection can be considered. At this time, as an example, the terminal may receive a signal corresponding to one or multiple SLSSIDs. If the RSRP value of the signals exceeds the set reference value and the terminal receives one or more SL-V2X-MIB information transmitted through the PSBCH channel or receives reliable GNSS, the priority as shown in Table 11 below You can select a synchronous reference source based on the ranking group. At this time, in Table 11 below, “Case 1” may be a case of acquiring SLSS for NR timing from a terminal in coverage of an LTE/NR cell. Additionally, “Case 2” may refer to a case where the SLSS for NR timing is acquired from a terminal in coverage of an LTE/NR cell, but is received from an OOC terminal. That is, this may be the case where the OOC terminal is provided based on information obtained from the IC terminal.

Additionally, “Case 3” may refer to a case where SLSS for LTE timing is acquired from a terminal within the coverage of an LTE/NR cell. Additionally, “Case 4” may refer to a case where SLSS for LTE timing is acquired from a terminal in coverage of an LTE/NR cell, but is received from an OOC terminal. That is, this may be the case where the OOC terminal is provided based on information obtained from the IC terminal.

Additionally, “Case 5” may refer to a case where GNSS timing is obtained directly from GNSS.

Additionally, “Case 6” may refer to a case where SLSS for GNSS timing is acquired from a terminal within coverage of an LTE/NR cell. Additionally, “Case 7” may refer to a case where SLSS for GNSS timing is acquired from a terminal within coverage of an LTE/NR cell, but is received from an OOC terminal. That is, this may be the case where the OOC terminal is provided based on information obtained from the IC terminal. Additionally, “Case 8” may refer to a case where GNSS timing is acquired from an OOC terminal and transmitted by an OOC terminal.

[Table 11]

At this time, the following examples can be performed based on the above-mentioned Table 11, which will be described later.

Example 2-1

In Example 2-1, the synchronization priority (SyncPriority) value in the pre-configuration can be set based on “NG-RAN” and “GNSS” that integrate NR and LTE timing sources into one priority. More specifically, in Table 11 above, the NR timing and LTE timing sources may be different from each other, but they can be integrated into “NG-RAN” to set a priority value in relation to GNSS. In other words, two can be defined in terms of the SyncPriority parameter within the corresponding preconfiguration. In consideration of the above, in the following, receiving an SLSSID value with NG-RAN timing may mean that the terminal receives one or more SLSS signals with LTE cell or NR cell timing. there is. As an example, the terminal may receive one or more SLSS signals corresponding to LTE cell timing or NR cell timing from a V2X transmitting terminal present in an LTE cell or NR cell. At this time, if the received signals have an RSRP value greater than the reference value, it may be determined that the received signals belong to the same priority group. At this time, the tables below may be priority groups presented based on the above.

As an example, Table 12 may be a case where the SyncPriority order is set to “GNSS (1st)->NG-RAN (2nd)” in the preconfiguration. That is, there may be a case where GNSS timing takes precedence over NG-RAN timing. Additionally, as an example, the above-described case may be the same as the case where SyncPriority is set to “GNSS” in the preconfiguration. Meanwhile, NG-RAN timing may be LTE cell or NR cell timing, as described above. At this time, referring to Table 12, the group that receives GNSS timing directly from GNSS may have the highest priority. In addition, groups for obtaining SLSS for NG-RAN timing or SLSS for GNSS timing from NG-RAN coverage terminals may have the same priority. In addition, as the next priority, SLSS for NG-RAN timing or SLSS for GNSS timing is acquired from coverage terminals of NG-RAN, but when received from an OOC terminal or when GNSS timing is acquired from an OOC terminal, the It can have the following priorities:

That is, based on Table 12, GNSS has priority over NG-RAN, so receiving timing directly from GNSS may be given priority. Next, receiving timing information from an NG-RAN coverage terminal may have the next priority, and receiving timing information from an OOC terminal may have a lower priority.

[Table 12]

Additionally, as an example, Table 13 may be a case where the SyncPriority order is set to “NG-RAN (1st)->GNSS (2nd)” in the preconfiguration. That is, there may be a case where NG-RAN timing takes precedence over GNSS timing. Additionally, as an example, the above-described case may be the same as the case where SyncPriority is set to “NG-RAN” in the preconfiguration. Meanwhile, NG-RAN timing may be LTE cell or NR cell timing, as described above. At this time, referring to Table 13, the group for obtaining SLSS for NG-RAN timing from NG-RAN coverage terminals may have the highest priority. Next, the group for the case where the SLSS for NG-RAN timing is acquired from the coverage terminals of the NG-RAN but is received from the OOC terminal may be the next priority. Next, the group for cases where timing is received directly from GNSS may be the next priority. Next, the group for obtaining SLSS for GNSS timing from coverage terminals of NG-RAN may be the next priority. Next, the group for cases where SLSS for GNSS timing is acquired from coverage terminals of NG-RAN but received from OOC terminals may be the next priority. Next, obtaining SLSS for GNSS timing from the NG-RAN OOC terminal may be the next priority.

[Table 13]

Example 2-2

Example 2-2 may be a method of limiting the number of methods for determining priority, and Example 2-2-1 below may be a case of limiting the method of determining priority to three cases. Example 2-2-2 may be a case where the methods for determining priority are limited to six.

More specifically, in Example 2-2-1, a case may be considered where the group for GNSS timing has the highest priority, and the group for LTE timing and NR timing have equal priority. That is, similar to Example 2-1, GNSS and eNB/NG can be compared. Of course, even if the eNB and NR have equal priorities, in Example 2-2-1, the group priorities for GNSS timing, LTE timing, and NR timing can be compared, respectively. Additionally, in Example 2-2-1, three cases can be considered: a case where eNB/NG takes priority over GNSS, a case where eNB takes precedence over NG, and a case where NG takes precedence over eNB.

Meanwhile, in 2-2-2, the priorities of groups for GNSS timing, LTE timing, and NR timing can be compared, respectively. In other words, a case based on a combination of three parameters can be derived, and six cases can be considered, which will be described later.

Example 2-2-1

In Example 2-2-1, as described above, the method of determining the priority according to which parameters have been set in advance may be limited to only three cases. That is, the priority group can be divided into only three possible cases. At this time, referring to Table 14 below, the SyncPriority order may be set to “GNSS (1st) > eNB (2nd) = NR (2nd)” in the preconfiguration. As an example, the above-mentioned case may be the same as the case where “GNSS” is set in the synchronization priority (SyncPriority) in the preconfiguration. Therefore, when GNSS is set, signals received directly from GNSS can be given top priority. At the same time, the LTE/NR/GNSS timing of SLSS transmitted within network coverage can be given next priority. Next, the LTE/NR/GNSS timing of SLSSs transmitted outside of network coverage can be prioritized, and finally, SLSSs that are not transmitted outside of network coverage can be made to belong to the last priority group, as shown in Table 14.

[Table 14]

Additionally, as an example, Table 15 may be a case where the SyncPriority order is set to “NR(1st)->eNB(2nd)->GNSS(3rd)” in the preconfiguration. As an example, the above-mentioned case may be the same as the case where “NR” is set in the synchronization priority (SyncPriority) in the preconfiguration. Therefore, the group for cases where SLSS for NR timing is obtained from the LTE/NR coverage terminal may be given top priority. Next, the group for cases where SLSS for LTE timing is obtained from the LTE/NR coverage terminal may be prioritized next. Next, a group for cases where SLSS for NR timing is acquired from an LTE/NR coverage terminal but received from an OOC terminal may be prioritized next. Next, a group for cases where SLSS for LTE timing is acquired from an LTE/NR coverage terminal but received from an OOC terminal may be prioritized next. Next, the group for cases where SLSS for GNSS timing is acquired from an LTE/NR coverage terminal may be prioritized next. Next, a group for cases where SLSS for GNSS timing is acquired from an LTE/NR coverage terminal but received from an OOC terminal may be prioritized next. Next, the group for cases where SLSS for GNSS timing is received from the OOC terminal may be given priority.

[Table 15]

Additionally, as an example, Table 16 may be a case where the synchronization priority order is set to “eNB (1st) -> NR (2nd) -> GNSS (3rd)” in the preconfiguration. As an example, the above-described case may be the same as the case where “eNB” is set as the synchronization priority in the preconfiguration. Therefore, the group for cases where SLSS for LTE timing is obtained from the LTE/NR coverage terminal may be given top priority. Next, the group for cases where SLSS for NR timing is acquired from the LTE/NR coverage terminal may be prioritized next. Next, a group for cases where SLSS for LTE timing is acquired from an LTE/NR coverage terminal but received from an OOC terminal may be prioritized next. Next, a group for cases where SLSS for NR timing is acquired from an LTE/NR coverage terminal but received from an OOC terminal may be prioritized next. Next, the group for cases where SLSS for GNSS timing is acquired from an LTE/NR coverage terminal may be prioritized next. Next, a group for cases where SLSS for GNSS timing is acquired from an LTE/NR coverage terminal but received from an OOC terminal may be prioritized next. Next, the group for cases where SLSS for GNSS timing is received from the OOC terminal may be given priority.

[Table 16]

Example 2-2-2

As described above, Embodiment 2-2-2 may be an embodiment that considers all six cases (GNSS timing, LTE timing, and NG timing comparison). That is, unlike Example 2-2-1, the priority groups can be divided for all six possible combinations.

At this time, as an example, Table 17 may be a case where the synchronization priority order (SyncPriority order) is set to “GNSS (1st) -> eNB (2nd) -> NR (3rd)” in the preconfiguration. Therefore, when GNSS is set, the signal received directly from GNSS can be given top priority. Next, among SLSSs transmitted within network coverage, the SLSS with LTE timing may have the next priority. Next, SLSS with NR timing may have the next priority. Next, SLSS with GNSS timing may have the next priority. Next, among SLSSs transmitted outside of network coverage, the SLSS with LTE timing may have the next priority. Next, SLSS with NR timing may have the next priority. Next, SLSS with GNSS timing may have the next priority. Lastly, the SLSSs that do not belong to the last priority group, as shown in Table 17 below.

[Table 17]

Next, if the SyncPriority order is set to “GNSS (1st)->NR (2nd)->eNB (3rd)” in the preconfiguration, it may be as shown in Table 18 below. At this time, Table 18 may be similar to Table 17, and only the priorities of LTE timing and NR timing may be changed, and the specific configuration is as shown in Table 18 below.

[Table 18]

Next, if the SyncPriority order is set to “NR(1st)->eNB(2nd)->GNSS(3rd)” in the preconfiguration, it may be as shown in Table 19 below.

[Table 19]

Next, if the SyncPriority order is set to “eNB (1st)->NR (2nd)->GNSS (3rd)” in the preconfiguration, it may be as shown in Table 20 below.

[Table 20]

Next, if the SyncPriority order is set to “NR(1st)->GNSS(2nd)->eNB(3rd)” in the preconfiguration, it may be as shown in Table 21 below.

[Table 21]

Next, if the SyncPriority order is set to “eNB (1st)->GNSS (2nd)->NR (3rd)” in the preconfiguration, it may be as shown in Table 22 below.

[Table 22]

Figure 8 is a flowchart considering Example 2-2 (2-2-1 and 2-2-2).

Referring to Figure 8, when the frequency for V2X sidelink communication is out of coverage (OOC), the terminal can select a synchronization reference source. (S810) At this time, since it is OOC, the terminal can determine the priority method based on preset parameters in preconfiguration. (S820) At this time, as an example, the priority method may be determined by limiting it to only three cases as in Example 2-2-1. That is, as in the above-described embodiment 2-2-1, the GNSS timing and LTE timing/NR timing are compared, and the method may be limited as in the above-described embodiment. Additionally, as an example, all six cases can be considered, as in Example 2-2-2 described above. That is, all possible combinations can be considered based on GNSS timing, LTE timing, and NR timing, respectively. Afterwards, the terminal can select a synchronization reference source through priority based on the SyncPriority order in the preconfiguration, and the specific method is as described above. (S830)

Meanwhile, as an example, it may also be preset whether the priority will be determined based on which method of Example 2-2-1 or Example 2-2-2 described above. That is, the terminal can support the methods of Example 2-2-1 and Example 2-2-2 described above, but can determine priority based on any one of the methods described above based on a preset value. , but is not limited to the above-described embodiments.

Example 3 (when the frequency for V2X sidelink communication of the NR V2X sidelink terminal is out of coverage (OOC) on a 3GPP network corresponding to LTE/NR)

Example 3, like Example 2, may be an embodiment for a case where the frequency for V2X sidelink communication of the terminal is OOC on a 3GPP network corresponding to LTE/NR. At this time, as an example, a priority group within each synchronization reference source may be defined. The priority between the three defined groups can be indicated by defining the SyncPriority order parameter in the preconfiguration. At this time, as an example, the SyncPriority order parameter may determine only the priority for each group. For example, when the SyncPriority order is set to “NR(1st)->eNB(2nd)->GNSS(3rd)” in the preconfiguration, the priorities between each group are Table 23, Table 23. 24 and Table 25. Additionally, as an example, the rankings within the group may all be the same, and are not limited to the above-described embodiment.

[Table 23]

[Table 24]

[Table 25]

In addition, as an example, when the SyncPriority order is set to “NR (1st)->GNSS (2nd)->eNB (3rd)” in the preconfiguration, the priority between each group is Table 26 , can be determined as Table 27 and Table 28. Additionally, as an example, the rankings within the group may all be the same, and are not limited to the above-described embodiment.

[Table 26]

[Table 27]

[Table 28]

In addition, as an example, if the SyncPriority order is set to “GNSS (1st)->eNB (2nd)->NR (3rd)” in the preconfiguration, based on Tables 26 to 28 described above Therefore, priorities can be set as shown in Table 29 below.

[Table 29]

In addition, as an example, if the synchronization priority order is set to “GNSS (1st) -> NR (2nd) -> eNB (3rd)” in the preconfiguration, based on Tables 26 to 28 described above Therefore, priorities can be set as shown in Table 30 below.

[Table 30]

Additionally, as an example, if the SyncPriority order is set to “eNB (1st)->GNSS (2nd)->NR (3rd)” in the preconfiguration, based on Tables 26 to 28 described above. Therefore, priorities can be set as shown in Table 31 below.

[Table 31]

In addition, as an example, if the synchronization priority order is set to “eNB (1st) -> NR (2nd) -> GNSS (3rd)” in the preconfiguration, based on Tables 26 to 28 described above Therefore, priorities can be set as shown in Table 32 below.

[Table 32]

That is, the priority group among GNSS timing, LTE timing, and NR timing is determined based on the synchronization priority order in the preconfiguration, and the priority can be determined again within that group, and the above-described embodiments It is not limited to

Example 4 (Additional Prioritization Method)

Additionally, as an example, in embodiments 2 and 3, when a plurality of signals for a synchronization reference source exist within the same priority group, priorities may be additionally determined among the plurality of signals. In particular, when the SLSSID corresponding to the LTE timing and the NR timing is received (NG-RAN timing), the terminal can determine the priority between the two. At this time, as an example, when comparing multiple signals, the terminal can determine the reference source by comparing the “RSRP value” or “RSRP value and SCS value” of the signals from the two received sources.

More specifically, the method of comparing the “RSRP value” is to compare the RSRP value corresponding to the reception sensitivity of the signal from two sources corresponding to LTE timing and NR timing, and compare the RSRP value corresponding to the reception sensitivity of the signal from the two sources corresponding to the LTE timing and the NR timing. 3GPP network timing with a larger value among the signals may be used and may be similar to Example 1.

Alternatively, the method of comparing the “RSRP value and SCS value” is to compare the RSRP value corresponding to the reception sensitivity of the signal from two sources corresponding to LTE timing and NR timing, and compare the RSRP value corresponding to the reception sensitivity of the signal from the two sources corresponding to the LTE timing and NR timing. Among the signals, 3GPP network timing with a larger SCS value can be used. This is because the timing of an NR cell that can configure 30, 60, 120, and 240 kHz SCS in addition to 15 kHz SCS can have a higher time resolution than the timing of an LTE cell based on only 15 kHz SCS, which is an embodiment It may be similar to 1. In other words, the transmission and reception timing for NR V2X sidelink transmission and reception can be adjusted and utilized in more detail, providing advantages in terms of resource utilization and compatibility with NR SL.

Example 5 (Synchronous Reference Source Reselection)

As another example, a terminal that has selected a synchronization reference source at least once based on the above-described information may perform an operation to reselect the synchronization reference source.

More specifically, in the OOC case, a case where a UE that has already selected a synchronization reference source through the above-described method may select one synchronization reference terminal (SyncRef UE) can be considered. At this time, as an example, another RSRP value (candidate SyncRef UE) is greater than or equal to a preset reference value (a certain value for minimum requirements), and another RSRP value (candidate SyncRef UE) has the same priority as the current synchronous reference terminal (SyncRef UE). Cases belonging to a group can be considered. At this time, if another RSRP value (candidate SyncRef UE) is greater than the RSRP value of the current synchronization reference terminal (SyncRef UE) than a preset value (a certain value for minimum requirements), the synchronization source for the current synchronization reference terminal (SyncRef UE) will not be selected. You can. That is, based on the above-mentioned conditions, if there is a signal corresponding to the highest priority group among the synchronization reference terminals (SyncRef UE), the synchronization reference terminal (SyncRef UE) can be selected.

Additionally, as an example, if another RSRP value (candidate SyncRef UE) is above a preset reference value (a certain value for minimum requirements) and another RSRP value (candidate SyncRef UE) belongs to a higher priority group, the current synchronization reference A synchronization source for the terminal may not be selected. That is, based on the above-mentioned conditions, if there is a signal corresponding to the highest priority group among the synchronization reference terminals (SyncRef UE), the synchronization reference terminal (SyncRef UE) can be selected.

In addition, as an example, if the reliability of the GNSS signal is higher than a preset reference value (a certain value for minimum requirements) and the GNSS belongs to a higher priority group than the current synchronization reference terminal (SyncRef UE), You may not select a synchronization source. That is, based on the above-mentioned conditions, if there is a signal corresponding to the highest priority group among the synchronization reference terminals (SyncRef UE), the synchronization reference terminal (SyncRef UE) can be selected.

Additionally, as an example, if the RSRP value of the current synchronization reference terminal (SyncRef UE) is below a preset reference value (a certain value for minimum requirements), the synchronization source for the current synchronization reference terminal may not be selected. That is, based on the above-mentioned conditions, if there is a signal corresponding to the highest priority group among the synchronization reference terminals (SyncRef UE), the synchronization reference terminal (SyncRef UE) can be selected.

Additionally, as an example, a case where the terminal selects GNSS may be considered.

At this time, if the other RSRP value (candidate SyncRef UE) is higher than the preset reference value (a certain value for minimum requirements), and the candidate reference UE (candidate SyncRef UE) belongs to a higher priority group than the GNSS, the corresponding GNSS is not selected. It may not be possible. Additionally, as an example, even if the reliability of the GNSS signal is lower than a preset reference value (a certain value for minimum requirements), the corresponding GNSS may not be selected, and is not limited to the above-described embodiment.

Figure 9 is a diagram showing the configuration of a base station device and a terminal device according to the present disclosure.

The base station device 900 may include a processor 910, an antenna unit 920, a transceiver 930, and a memory 940.

The processor 910 performs baseband-related signal processing and may include an upper layer processing unit 911 and a physical layer processing unit 912. The upper layer processing unit 911 may process operations of a MAC (Medium Access Control) layer, RRC (Radio Resource Control) layer, or higher layers. The physical layer processing unit 912 may process physical (PHY) layer operations (e.g., uplink reception signal processing, downlink transmission signal processing). In addition to performing baseband-related signal processing, the processor 910 may also control the overall operation of the base station device 900.

The antenna unit 920 may include one or more physical antennas, and when it includes multiple antennas, it may support Multiple Input Multiple Output (MIMO) transmission and reception. Transceiver 930 may include a radio frequency (RF) transmitter and an RF receiver. The memory 940 may store information processed by the processor 910, software related to the operation of the base station device 900, an operating system, applications, etc., and may also include components such as buffers.

The processor 910 of the base station 900 may be configured to implement the operations of the base station in the embodiments described in the present invention.

The terminal device 950 may include a processor 960, an antenna unit 970, a transceiver 980, and a memory 990.

The processor 960 performs baseband-related signal processing and may include an upper layer processing unit 961 and a physical layer processing unit 962. The upper layer processing unit 961 can process operations of the MAC layer, RRC layer, or higher layers. The physical layer processing unit 962 may process PHY layer operations (e.g., downlink received signal processing, uplink transmitted signal processing). In addition to performing baseband-related signal processing, the processor 960 may also control the overall operation of the terminal device 950.

The antenna unit 970 may include one or more physical antennas, and may support MIMO transmission and reception when it includes a plurality of antennas. Transceiver 980 may include an RF transmitter and an RF receiver. The memory 990 may store information processed by the processor 960, software related to the operation of the terminal device 950, an operating system, applications, etc., and may also include components such as buffers.

The processor 960 of the terminal device 950 may be configured to implement the operations of the terminal in the embodiments described in the present invention.

Matters described in the examples of the present invention may be applied in the same manner to the operations of the base station device 900 and the terminal device 950, and overlapping descriptions will be omitted.

Exemplary methods of the present disclosure are expressed as a series of operations for clarity of explanation, but this is not intended to limit the order in which the steps are performed, and each step may be performed simultaneously or in a different order, if necessary. In order to implement the method according to the present disclosure, other steps may be included in addition to the exemplified steps, some steps may be excluded and the remaining steps may be included, or some steps may be excluded and additional other steps may be included.

The various embodiments of the present disclosure do not list all possible combinations but are intended to explain representative aspects of the present disclosure, and matters described in the various embodiments may be applied independently or in combination of two or more.

Additionally, various embodiments of the present disclosure may be implemented by hardware, firmware, software, or a combination thereof. For hardware implementation, one or more ASICs (Application Specific Integrated Circuits), DSPs (Digital Signal Processors), DSPDs (Digital Signal Processing Devices), PLDs (Programmable Logic Devices), FPGAs (Field Programmable Gate Arrays), general purpose It can be implemented by a processor (general processor), controller, microcontroller, microprocessor, etc.

The scope of the present disclosure is software or machine-executable instructions (e.g., operating system, application, firmware, program, etc.) that cause operations according to the methods of various embodiments to be executed on a device or computer, and such software or It includes non-transitory computer-readable medium in which instructions, etc. are stored and can be executed on a device or computer.

Base Station: 900 Processor: 910
Upper layer processing unit: 911 Physical layer processing unit: 912
Antenna unit: 920 Transceiver: 930
Memory: 940 Terminal: 950
Processor: 960 Upper layer processor: 961
Physical layer processing unit: 962 Antenna unit: 970
Transceiver: 980 Memory: 990

Claims (8)

In how the terminal performs a synchronization procedure,
determining whether the terminal is within network coverage;
selecting a synchronization reference source based on whether the terminal is within the network coverage; and
Including performing synchronization based on the selected synchronization reference source,
When the terminal is within the network coverage and a synchronization type parameter is provided, the synchronization reference source is a global navigation satellite system (GNSS) or a sidelink synchronization signal (SLSS) based on the synchronization type parameter. ) is selected based on at least one of a signal, long term evolution (LTE) cell timing, and new radio (NR) cell timing,
If the terminal is within network coverage and the synchronization type parameter is not provided, determine whether to select the GNSS as the synchronization reference source based on the reliability of the GNSS, but if the reliability of the GNSS is not satisfied, the Determine whether to select an SLSS with an SLSS ID (identifier) value corresponding to GNSS timing as the synchronization reference source,
When the terminal is outside the network coverage, the synchronization reference source is selected according to a sync priority order determined based on pre-configuration parameters, and when the synchronization priority order is determined, the LTE Cell timing and the NR cell timing are set to NG-RAN timing with the same priority, and the synchronization priority is determined based on the NG-RAN timing and the GNSS timing.
According to clause 1,
A method of performing a synchronization procedure, wherein whether the reliability of the GNSS is satisfied is determined based on whether the signal strength of the GNSS is greater than or equal to a threshold value.
According to clause 1,
A method of performing a synchronization procedure, wherein the SLSS having the SLSS ID (identifier) value corresponding to the GNSS timing is transmitted from a terminal that directly receives the GNSS timing.
According to clause 3,
When the terminal fails to detect the SLSS transmitted from the terminal that directly receives the GNSS timing, the terminal selects the synchronization reference element based on at least one of the LTE cell timing and the NR cell timing. How to perform the synchronization procedure.
In a terminal performing a synchronization procedure,
transceiver; and
Includes a processor connected to the transceiver,
The processor,
Determine whether the terminal is within network coverage,
select a synchronization reference source based on whether the terminal is within the network coverage, and
Perform synchronization based on the selected synchronization reference source,
When the terminal is within the network coverage and a synchronization type parameter is provided, the synchronization reference source is a global navigation satellite system (GNSS) or a sidelink synchronization signal (SLSS) based on the synchronization type parameter. ) is selected based on at least one of a signal, long term evolution (LTE) cell timing, and new radio (NR) cell timing,
If the terminal is within network coverage and the synchronization type parameter is not provided, determine whether to select the GNSS as the synchronization reference source based on the reliability of the GNSS, but if the reliability of the GNSS is not satisfied, the Determine whether to select an SLSS with an SLSS ID (identifier) value corresponding to GNSS timing as the synchronization reference source,
When the terminal is outside the network coverage, the synchronization reference source is selected according to a sync priority order determined based on pre-configuration parameters, and when the synchronization priority order is determined, the LTE Cell timing and the NR cell timing are set to NG-RAN timing with the same priority, and the synchronization priority is determined based on the NG-RAN timing and the GNSS timing. A terminal performing a synchronization procedure.
According to clause 5,
A terminal performing a synchronization procedure, wherein whether the reliability of the GNSS is satisfied is determined based on whether the signal strength of the GNSS is greater than or equal to a threshold value.
According to clause 6,
The SLSS having the SLSS ID (identifier) value corresponding to the GNSS timing is transmitted from the terminal that directly receives the GNSS timing. A terminal performing a synchronization procedure.
According to clause 7,
When the terminal fails to detect the SLSS transmitted from the terminal that directly receives the GNSS timing, the terminal selects the synchronization reference element based on at least one of the LTE cell timing and the NR cell timing. A terminal that performs a synchronization procedure.

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