KR20200049590A - Methods for performing v2x communication and appratuses thereof - Google Patents

Abstract

The present invention relates to a method for providing a vehicle-to-everything (V2X) service in a new radio access technology (RAT), to transmit data with high reliability through vehicle communications, and an apparatus thereof. According to one embodiment of the present invention, the method comprises the following steps of: receiving sidelink radio bearer configuration information for configuring a sidelink radio bearer on a sidelink interface used for V2X communications from a base station; configuring the sidelink radio bearer based on the sidelink radio bearer configuration information and transmitting the sidelink radio bearer configuration information to other terminals which are targets of the V2X communications; when an AM RLC entity linked with the sidelink radio bearer reaches a maximum retransmission frequency, detecting a sidelink radio link failure; and when the sidelink radio link failure is detected, directing detection of the sidelink radio link failure to an upper layer regardless of an RRC state of the terminal.

Description

Method and apparatus for performing vehicle communication {METHODS FOR PERFORMING V2X COMMUNICATION AND APPRATUSES THEREOF}

The present disclosure relates to a method and apparatus for providing a V2X service in the next generation radio access technology (New RAT).

There is a demand for large-scale data processing, high-speed data processing, and various service demands using wireless terminals in vehicles, industrial sites, and the like. As described above, there is a need for a technology for a high-speed and large-capacity communication system capable of processing large-scale data and various scenarios such as video, wireless data, and machine-type communication data beyond simply voice-oriented services.

To this end, ITU-R discloses the requirements for adopting the IMT-2020 international standard, and research is being conducted on the next generation wireless communication technology to meet the requirements of the IMT-2020.

In particular, 3GPP is conducting research on LTE-Advanced Pro Rel-15 / 16 standard and NR (New Radio Access Technology) standard in parallel to satisfy the IMT-2020 requirement called 5G technology. Plans to be approved as the next generation wireless communication technology.

In 5G technology, it can be applied and used in autonomous vehicles. For this, it is necessary to apply 5G technology to vehicle communication (V2X), and high-speed transmission / reception is required while autonomous driving guarantees high reliability for increased data.

In addition, in order to satisfy the driving scenarios of various autonomous vehicles such as cluster driving, it is necessary to guarantee not only unicast data transmission and reception using vehicle communication, but also multicast data transmission and reception.

In this situation, it is necessary to develop a technology for ensuring high reliability data transmission and reception in vehicle communication.

The present embodiments can provide a method and apparatus for performing vehicle communication using next-generation wireless access technology.

Further, the present embodiments can provide a technique for transmitting high reliability data through vehicle communication.

In one aspect, the present embodiments are a method for a terminal to perform vehicle communication (Vehicle to everything communication, V2X communication), a sidelink radio bearer for configuring a sidelink radio bearer on a sidelink interface used for vehicle communication Receiving the configuration information from the base station and configuring the sidelink radio bearer based on the sidelink radio bearer configuration information, transmitting the sidelink radio bearer configuration information to another terminal targeted for vehicle communication, and the sidelink radio bearer When the AM RLC entity linked to the maximum number of retransmissions has been reached, detecting a sidelink radio link failure and detecting a sidelink radio link failure, the sidelink radio link failure detection is higher regardless of the RRC state of the terminal. It is possible to provide a method comprising directing to a layer.

In another aspect, the present embodiments provide a side link radio bearer for configuring a side link radio bearer on a side link interface used for vehicle communication in a method for a base station to control vehicle to everything communication (V2X communication). Transmitting the configuration information to the terminal and receiving the sidelink failure information from the terminal, which occurs when the number of retransmissions of the transmitted data in the AM RLC entity configured in the terminal reaches the maximum number of retransmissions based on the sidelink radio bearer configuration information. It is possible to provide a method comprising steps.

In another aspect, the present embodiments are configured to configure a side link radio bearer for configuring a side link radio bearer on a side link interface used for vehicle communication in a terminal performing vehicle communication (Vehicle to everything communication). Based on the receiving unit receiving the information from the base station and the sidelink radio bearer configuration information, the sidelink radio bearer is configured, and when the AM RLC entity associated with the sidelink radio bearer reaches the maximum number of retransmissions, the sidelink radio link fails And a transmitter for transmitting sidelink radio bearer configuration information to another terminal targeted for vehicle communication, and when the sidelink radio link failure is detected, the controller irrespective of the RRC state of the terminal. The step that controls failure detection to be directed to the upper layer. It is possible to provide a device.

In yet another aspect, the present embodiments are configured for a side link radio bearer for configuring a side link radio bearer on a side link interface used for vehicle communication in a base station controlling vehicle communication (V2X communication). Receives sidelink failure information from the terminal, which is generated when the number of retransmissions of transmitted data in the AM RLC entity configured in the terminal reaches the maximum number of retransmissions based on the transmitter and sidelink radio bearer configuration information that transmits the information to the terminal. It can provide a base station apparatus including a receiving unit.

According to the present embodiments, it is possible to provide a method and apparatus for performing vehicle communication using next-generation wireless access technology.

1 is a diagram briefly showing a structure of an NR wireless communication system to which the present embodiment can be applied.
2 is a diagram for explaining a frame structure in an NR system to which the present embodiment can be applied.
3 is a diagram for describing a resource grid supported by a radio access technology to which the present embodiment can be applied.
4 is a diagram for describing a bandwidth part supported by a radio access technology to which the present embodiment can be applied.
5 exemplarily shows a synchronization signal block in a radio access technology to which the present embodiment can be applied.
6 is a diagram for explaining a random access procedure in a radio access technology to which the present embodiment can be applied.
7 is a view for explaining CORESET.
8 is a diagram for exemplarily illustrating symbol level alignment between different SCSs in a radio access technology to which the present embodiment can be applied.
9 is a view for explaining the type of vehicle communication to which the present embodiment can be applied.
10 exemplarily illustrates the architecture of a V2X communication system in an LTE system.
11 is a diagram for describing a terminal operation according to an embodiment.
12 is a diagram for explaining an operation of a base station according to an embodiment.
13 is a view for explaining a terminal configuration according to an embodiment.
14 is a diagram for explaining a configuration of a base station according to an embodiment.

Hereinafter, some embodiments of the present disclosure will be described in detail with reference to exemplary drawings. In adding reference numerals to the components of each drawing, the same components may have the same reference numerals as possible even though they are displayed on different drawings. In addition, in describing the embodiments, when it is determined that a detailed description of a related known configuration or function may obscure the gist of the present technical concept, the detailed description may be omitted. When "include", "have", "consist of" and the like referred to herein are used, other parts may be added unless "~ only" is used. When a component is expressed in singular, it may include a case in which plural is included unless otherwise specified.

In addition, in describing the components of the present disclosure, terms such as first, second, A, B, (a), and (b) may be used. These terms are only for distinguishing the component from other components, and the essence, order, order, or number of the component is not limited by the term.

In the description of the positional relationship of the components, when two or more components are described as being "connected", "coupled" or "connected", etc., two or more components are directly "connected", "coupled" or "connected" It may be understood, but it may be understood that two or more components and other components may be further "interposed" to be "connected", "coupled" or "connected". Here, other components may be included in one or more of two or more components that are "connected", "coupled" or "connected" to each other.

In the description of temporal flow relations related to components, operation methods, production methods, etc., temporal sequential relationships such as "after", "after", "after", "before", etc. Or, when the flow sequential relationship is described, it may also include a case where the "direct" or "direct" is not continuous unless used.

On the other hand, when a numerical value for a component or its corresponding information (such as a level) is mentioned, even if there is no explicit description, the numerical value or its corresponding information is various factors (eg, process factors, internal or external impact, Noise, etc.).

The wireless communication system in the present specification means a system for providing various communication services such as voice and data packets using radio resources, and may include a terminal and a base station or a core network.

The embodiments disclosed below can be applied to a wireless communication system using various wireless access technologies. For example, the present embodiments are code division multiple access (CDMA), frequency division multiple access (FDMA), timedivision multiple access (TDMA), orthogonal frequency division multiple access (OFDMA), and single-electron frequency division multiple access (SC-FDMA). Alternatively, it may be applied to various various wireless access technologies such as non-orthogonal multiple access (NOMA). In addition, the wireless access technology may mean not only a specific access technology, but also a communication technology for each generation established by various communication consultation organizations such as 3GPP, 3GPP2, WiFi, Bluetooth, IEEE, and ITU. For example, CDMA may be implemented with a radio technology such as universal terrestrial radio access (UTRA) or CDMA2000. TDMA may be implemented with radio technologies such as global system for mobile communications (GSM) / general packet radio service (GPRS) / enhanced data rates for GSM evolution (EDGE). OFDMA may be implemented with wireless technologies such as the Institute of Electrical and Electronics Engineers (IEEE) 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802-20, and Evolved UTRA (E-UTRA). IEEE 802.16m is an evolution of IEEE 802.16e, and provides backward compatibility with a system based on IEEE 802.16e. UTRA is part of a universal mobile telecommunications system (UMTS). 3rd generation partnership project (3GPP) long term evolution (LTE) is part of evolved UMTS (E-UMTS) using evolved-UMTS terrestrial radio access (E-UTRA), adopts OFDMA in the downlink and SC- in the uplink. Adopt FDMA. As described above, the present embodiments may be applied to a currently disclosed or commercialized wireless access technology, or may be applied to a wireless access technology currently being developed or to be developed in the future.

On the other hand, the terminal in the present specification is a comprehensive concept meaning a device including a wireless communication module that performs communication with a base station in a wireless communication system, WCDMA, LTE, NR, HSPA and IMT-2020 (5G or New Radio), etc. It should be interpreted as a concept including all of User Equipment (UE), Mobile Station (MS) in GSM, User Station (UT), Subscriber Station (SS), and wireless device. In addition, the terminal may be a user portable device such as a smart phone depending on the type of use, and in the V2X communication system, it may mean a vehicle, a device including a wireless communication module in the vehicle, or the like. Also, in the case of a machine type communication system, it may mean an MTC terminal, a M2M terminal, a URLLC terminal, etc. equipped with a communication module so that the machine type communication is performed.

The base station or cell herein refers to an end that communicates with a terminal in terms of a network, Node-B (Node-B), evolved Node-B (eNB), gNode-B (gNB), Low Power Node (LPN), Sector, Site, Various types of antennas, Base Transceiver System (BTS), Access Point, Point (e.g., Send Point, Receive Point, Send / Receive Point), Relay Node (Relay Node) ), Mega cell, macro cell, micro cell, pico cell, femto cell, remote radio head (RRH), radio unit (RU), and small cell (small cell). In addition, the cell may mean to include a bandwidth part (BWP) in the frequency domain. For example, the serving cell may mean the Activation BWP of the terminal.

Since the various cells listed above have a base station that controls one or more cells, the base station can be interpreted in two ways. 1) a device that provides a mega cell, a macro cell, a micro cell, a pico cell, a femto cell, and a small cell in relation to the wireless area, or 2) the wireless area itself. In 1), all devices that provide a predetermined wireless area are controlled by the same entity or interact to configure the wireless area in a collaborative manner. Points, transmission / reception points, transmission points, reception points, and the like, according to a configuration method of a wireless area, are examples of a base station. In 2), the radio area itself, which receives or transmits a signal from the viewpoint of the user terminal or the neighboring base station, may be directed to the base station.

In this specification, a cell is a component carrier having a coverage of a signal transmitted from a transmission / reception point or a signal transmitted from a transmission / reception point, or a transmission / reception point itself. Can be.

Uplink (Uplink, UL, or uplink) means a method of transmitting and receiving data to the base station by the terminal, downlink (Downlink, DL, or downlink) means a method of transmitting and receiving data to the terminal by the base station do. A downlink may mean a communication path or communication path from multiple transmission / reception points to a terminal, and an uplink may mean a communication path or communication path from terminal to multiple transmission / reception points. At this time, in the downlink, the transmitter may be a part of multiple transmission / reception points, and the receiver may be a part of the terminal. In addition, in the uplink, the transmitter may be a part of the terminal, and the receiver may be a part of the multiple transmission / reception points.

In the uplink and downlink, control information is transmitted and received through control channels such as a physical downlink control channel (PDCCH), a physical uplink control channel (PUCCH), and a physical downlink shared channel (PDSCH), a physical uplink shared channel (PUSCH), and the like. The same data channel is configured to transmit and receive data. Hereinafter, a situation in which signals are transmitted / received through channels such as PUCCH, PUSCH, PDCCH and PDSCH is also described in the form of 'transmit and receive PUCCH, PUSCH, PDCCH and PDSCH'.

In order to clarify the description, hereinafter, this technical idea mainly describes a 3GPP LTE / LTE-A / NR (New RAT) communication system, but this technical feature is not limited to the corresponding communication system.

3GPP develops 5G (5th-Generation) communication technology to meet the requirements of ITU-R's next-generation radio access technology after research on 4G (4th-Generation) communication technology. Specifically, 3GPP develops a new NR communication technology separate from LTE-A pro and 4G communication technology, which have improved LTE-Advanced technology to meet the requirements of ITU-R as a 5G communication technology. LTE-A pro and NR both refer to 5G communication technology. Hereinafter, 5G communication technology will be described with reference to NR when a specific communication technology is not specified.

The operating scenario in NR defined various operation scenarios by adding considerations for satellites, automobiles, and new verticals in the existing 4G LTE scenarios.In terms of service, it has an eMBB (Enhanced Mobile Broadband) scenario, high terminal density, but wide It is deployed in the range and supports the Massive Machine Communication (mmmTC) scenario, which requires low data rate and asynchronous connection, and the Ultra Reliability and Low Latency (URLLC) scenario, which requires high responsiveness and reliability and supports high-speed mobility. .

To satisfy this scenario, NR discloses a wireless communication system to which a new waveform and frame structure technology, low latency technology, ultra-high-bandwidth (mmWave) support technology, and forward compatibility technology are applied. In particular, in the NR system, various technical changes are proposed in terms of flexibility in order to provide forward compatibility. The main technical features of NR will be described below with reference to the drawings.

<NR system general>

1 is a diagram briefly showing the structure of an NR system to which the present embodiment can be applied.

Referring to FIG. 1, the NR system is divided into 5GC (5G Core Network) and NR-RAN parts, and NG-RAN is controlled for a user plane (SDAP / PDCP / RLC / MAC / PHY) and user equipment (UE). It consists of gNB and ng-eNBs that provide a plane (RRC) protocol termination. The gNB interconnects or the gNB and ng-eNB are interconnected via an Xn interface. gNB and ng-eNB are each connected to 5GC through an NG interface. The 5GC may include an Access and Mobility Management Function (AMF), which is responsible for a control plane such as a terminal access and mobility control function, and a User Plane Function (UPF), which is a control function for user data. The NR includes support for frequencies below 6 GHz (FR1, Frequency Range 1) and frequencies above 6 GHz (FR2, Frequency Range 2).

gNB means a base station providing NR user plane and control plane protocol termination to the terminal, and ng-eNB means a base station providing E-UTRA user plane and control plane protocol termination to the terminal. The base station described in this specification should be understood as a meaning encompassing gNB and ng-eNB, and may be used in a sense to refer to a gNB or ng-eNB as necessary.

<NR wave form, pneumatics and frame structure>

In NR, a CP-OFDM waveform using a cyclic prefix is used for downlink transmission, and CP-OFDM or DFT-s-OFDM is used for uplink transmission. OFDM technology is easy to combine with multiple input multiple output (MIMO), and has the advantage of being able to use a low-complexity receiver with high frequency efficiency.

On the other hand, in the NR, since the demands for data rate, delay rate, and coverage for each of the three scenarios described above are different from each other, it is necessary to efficiently satisfy the requirements for each scenario through a frequency band constituting an arbitrary NR system. . To this end, a technique for efficiently multiplexing a plurality of different numerology-based radio resources has been proposed.

Specifically, the NR transmission numerology is determined based on sub-carrier spacing (CP) and cyclic prefix (CP), and μ value is used as an exponential value of 2 based on 15khz as shown in Table 1 below. Is changed to

μ Subcarrier spacing Cyclic prefix Supported for data Supported for synch 0 15 Normal Yes Yes One 30 Normal Yes Yes 2 60 Normal, Extended Yes No 3 120 Normal Yes Yes 4 240 Normal No Yes

As shown in Table 1 above, the NR numerology can be divided into 5 types according to the subcarrier spacing. This is different from that in which the subcarrier spacing of LTE, which is one of 4G communication technologies, is fixed at 15 kHz. Specifically, subcarrier intervals used for data transmission in NR are 15, 30, 60, and 120 kHz, and subcarrier intervals used for synchronization signal transmission are 15, 30, 120, and 240 kHz. In addition, the extended CP is applied only to the 60 kHz subcarrier interval. On the other hand, the frame structure (frame structure) in the NR is defined as a frame having a length of 10ms consisting of 10 subframes (subframes) having the same length of 1ms. One frame can be divided into 5 ms half frames, and each half frame includes 5 subframes. In the case of a 15 kHz subcarrier interval, one subframe is composed of one slot, and each slot is composed of 14 OFDM symbols.

As shown in Table 1 above, the NR numerology can be divided into 5 types according to the subcarrier spacing. This is different from that in which the subcarrier spacing of LTE, which is one of 4G communication technologies, is fixed at 15khz. Specifically, the subcarrier interval used for data transmission in NR is 15, 30, 60, and 120 khz, and the subcarrier interval used for synchronization signal transmission is 15, 30, 12, and 240 khz. In addition, the extended CP applies only to the 60khz subcarrier spacing. On the other hand, the frame structure (frame structure) in the NR is defined as a frame having a length of 10ms consisting of 10 subframes (subframes) having the same length of 1ms. One frame can be divided into 5 ms half frames, and each half frame includes 5 subframes. In the case of a 15khz subcarrier interval, one subframe is composed of one slot, and each slot is composed of 14 OFDM symbols. 2 is a diagram for explaining a frame structure in an NR system to which the present embodiment can be applied.

Referring to FIG. 2, a slot is fixedly composed of 14 OFDM symbols in the case of a normal CP, but the length in the time domain of the slot may vary depending on the subcarrier interval. For example, in the case of a numerology having a 15 khz subcarrier spacing, the slot is 1 ms long and is configured to have the same length as the subframe. On the contrary, in the case of a neuromerlage having a 30 khz subcarrier spacing, a slot is composed of 14 OFDM symbols, but two slots may be included in one subframe with a length of 0.5 ms. That is, the subframe and the frame are defined with a fixed time length, and the slot is defined by the number of symbols, so that the time length may vary according to the subcarrier interval.

Meanwhile, the NR defines a basic unit of scheduling as a slot, and also introduces a mini-slot (or sub-slot or non-slot based schedule) to reduce transmission delay in a radio section. If a wide subcarrier interval is used, the length of one slot is inversely shortened, and thus transmission delay in a wireless section can be reduced. The mini-slot (or sub-slot) is for efficient support for the URLLC scenario and can be scheduled in units of 2, 4, and 7 symbols.

Also, unlike LTE, uplink and downlink resource allocation is defined as a symbol level within one slot. In order to reduce HARQ delay, a slot structure capable of directly transmitting HARQ ACK / NACK in a transmission slot has been defined, and this slot structure is referred to as a self-contained structure.

NR is designed to support a total of 256 slot formats, of which 62 slot formats are used in 3GPP Rel-15. In addition, a common frame structure constituting an FDD or TDD frame is supported through a combination of various slots. For example, a slot structure in which all symbols of a slot are set to downlink, a slot structure in which all symbols are set to uplink, and a slot structure in which downlink symbols and uplink symbols are combined are supported. In addition, NR supports that data transmissions are scheduled to be distributed in one or more slots. Accordingly, the base station can inform the terminal whether the slot is a downlink slot, an uplink slot, or a flexible slot using a slot format indicator (SFI). The base station may indicate a slot format by indicating an index of a table configured through UE-specific RRC signaling using SFI, and dynamically indicate through DCI (Downlink Control Information) or static or through RRC It can also be given quasi-statically.

<NR Physical Resources>

With regard to physical resources in NR, antenna ports, resource grids, resource elements, resource blocks, and bandwidth parts are considered. do.

The antenna port is defined such that a channel carrying a symbol on the antenna port can be inferred from a channel carrying another symbol on the same antenna port. If the large-scale property of a channel carrying a symbol on one antenna port can be inferred from a channel carrying a symbol on another antenna port, the two antenna ports are QC / QCL (quasi co-located or quasi co-location). Here, a wide range of characteristics includes one or more of delay spread, doppler spread, frequency shift, average received power, and received timing.

3 is a diagram for describing a resource grid supported by a radio access technology to which the present embodiment can be applied.

Referring to FIG. 3, a resource grid may exist according to each neuromerging because the NR supports a plurality of neuromerging on the same carrier. In addition, the resource grid may exist according to the antenna port, subcarrier spacing, and transmission direction.

A resource block is composed of 12 subcarriers and is defined only on the frequency domain. In addition, the resource element (resource element) is composed of one OFDM symbol and one subcarrier. Therefore, as shown in FIG. 3, the size of one resource block may vary according to the subcarrier interval. In addition, in NR, "Point A" serving as a common reference point for the resource block grid, a common resource block, and a virtual resource block are defined.

4 is a diagram for describing a bandwidth part supported by a radio access technology to which the present embodiment can be applied.

Unlike LTE, where the carrier bandwidth is fixed at 20Mhz in NR, the maximum carrier bandwidth is set from 50Mhz to 400Mhz for each subcarrier interval. Therefore, it is not assumed that all terminals use all of these carrier bandwidths. Accordingly, in the NR, as shown in FIG. 4, a terminal may be used by designating a bandwidth part (BWP) within the carrier bandwidth. In addition, the bandwidth part is associated with one neurology and is composed of a subset of consecutive common resource blocks, and can be dynamically activated with time. A maximum of 4 bandwidth parts are configured in the uplink and downlink, respectively, and data is transmitted and received using the bandwidth part activated at a given time.

In the case of a paired spectrum, the uplink and downlink bandwidth parts are independently set, and in the case of an unpaired spectrum, unnecessary frequency re-tunning is prevented between downlink and uplink operation. In order to achieve this, the bandwidth part of the downlink and uplink is set in pairs so that the center frequency can be shared.

<NR initial connection>

In NR, a terminal accesses a base station and performs a cell search and random access procedure to perform communication.

Cell search is a procedure in which a terminal synchronizes with a cell of a corresponding base station, acquires a physical layer cell ID, and acquires system information using a synchronization signal block (SSB) transmitted by the base station.

5 exemplarily shows a synchronization signal block in a radio access technology to which the present embodiment can be applied.

Referring to FIG. 5, the SSB is composed of a primary synchronization signal (PSS) and a secondary synchronization signal (SSS) and three OFDM symbols occupying one symbol and 127 subcarriers, respectively, and a PBCH spanning 240 subcarriers.

The UE receives the SSB by monitoring the SSB in the time and frequency domain.

SSB can be transmitted up to 64 times in 5 ms. Multiple SSBs are transmitted in different transmission beams within a 5 ms time period, and the UE performs detection by assuming that SSBs are transmitted every 20 ms periods based on a specific one beam used for transmission. The number of beams that can be used for SSB transmission within 5 ms time may increase as the frequency band increases. For example, up to 4 SSB beams can be transmitted at 3 GHz or less, and up to 8 SSBs can be transmitted using up to 8 different beams in the frequency band from 3 to 6 GHz and up to 64 in the frequency band above 6 GHz.

Two SSBs are included in one slot, and the starting symbol and the number of repetitions in the slot are determined according to the subcarrier interval.

On the other hand, SSB is not transmitted at the center frequency of the carrier bandwidth, unlike the SS of the conventional LTE. That is, the SSB may be transmitted out of the center of the system band, and when supporting broadband operation, a plurality of SSBs may be transmitted on the frequency domain. Accordingly, the terminal monitors the SSB using a synchronization raster, which is a candidate frequency location for monitoring the SSB. The carrier raster and the synchronization raster, which are the center frequency location information of the channel for initial access, are newly defined in the NR, and the synchronization raster has a wider frequency interval than the carrier raster, and thus supports fast SSB search of the UE. Can be.

The terminal may acquire MIB through the PBCH of the SSB. The MIB (Master Information Block) includes minimum information for the terminal to receive the remaining system information (RMSI, Remaining Minimum System Information) broadcast by the network. In addition, PBCH is information on the location of the first DM-RS symbol on the time domain, information for the UE to monitor SIB1 (for example, SIB1 neuromerging information, information related to SIB1 CORESET, search space information, PDCCH Related parameter information, etc.), offset information between the common resource block and the SSB (the position of the absolute SSB in the carrier is transmitted through SIB1), and the like. Here, the SIB1 numerology information is equally applied to some messages used in the random access procedure for accessing the base station after the terminal completes the cell search procedure. For example, pneumatic information of SIB1 may be applied to at least one of messages 1 to 4 for a random access procedure.

The aforementioned RMSI may mean System Information Block 1 (SIB1), and SIB1 is broadcast periodically (ex, 160 ms) in a cell. SIB1 includes information necessary for the UE to perform the initial random access procedure, and is periodically transmitted through the PDSCH. In order to receive SIB1, the UE must receive pneumatic information used for SIB1 transmission and control resource set (CORESET) information used for scheduling of SIB1 through the PBCH. The UE checks scheduling information for SIB1 using SI-RNTI in CORESET, and acquires SIB1 on the PDSCH according to the scheduling information. SIBs other than SIB1 may be periodically transmitted or may be transmitted according to a terminal request.

6 is a diagram for explaining a random access procedure in a radio access technology to which the present embodiment can be applied.

Referring to FIG. 6, when cell search is completed, the UE transmits a random access preamble for random access to the base station. The random access preamble is transmitted through PRACH. Specifically, the random access preamble is transmitted to the base station through PRACH composed of continuous radio resources in a specific slot that is periodically repeated. In general, a contention-based random access procedure is performed when the UE initially accesses a cell, and a non-competition-based random access procedure is performed when random access is performed for beam failure recovery (BFR).

The terminal receives a random access response to the transmitted random access preamble. The random access response may include a random access preamble identifier (ID), UL grant (uplink radio resource), temporary C-RNTI (Temporary Cell-Radio Network Temporary Identifier) and TAC (Time Alignment Command). Since one random access response may include random access response information for one or more terminals, a random access preamble identifier may be included to inform which terminal the included UL Grant, temporary C-RNTI, and TAC are valid. The random access preamble identifier may be an identifier for the random access preamble received by the base station. The TAC may be included as information for the UE to adjust uplink synchronization. The random access response may be indicated by a random access identifier on the PDCCH, that is, a Random Access-Radio Network Temporary Identifier (RA-RNTI).

Upon receiving a valid random access response, the terminal processes the information included in the random access response, and performs scheduled transmission to the base station. For example, the UE applies TAC and stores a temporary C-RNTI. In addition, by using UL Grant, data stored in the buffer of the terminal or newly generated data is transmitted to the base station. In this case, information capable of identifying the terminal should be included.

Finally, the terminal receives a downlink message for contention resolution.

<NR CORESET>

The downlink control channel in the NR is transmitted in a control resource set (CORESET) having a length of 1 to 3 symbols, and transmits up / down scheduling information, slot format index (SFI), and transmit power control (TPC) information. .

Thus, in order to secure the flexibility of the system, NR introduced the concept of CORESET. CORESET (Control Resource Set) means a time-frequency resource for a downlink control signal. The UE may decode the control channel candidate using one or more search spaces in the CORESET time-frequency resource. QCL (Quasi CoLocation) assumptions for each CORESET were established, and this is used to inform the characteristics of the analog beam direction in addition to delay spread, Doppler spread, Doppler shift, and average delay, which are characteristics assumed by the conventional QCL.

7 is a view for explaining CORESET.

Referring to FIG. 7, CORESET may exist in various forms within a carrier bandwidth within one slot, and CORESET may consist of up to 3 OFDM symbols in a time domain. In addition, CORESET is defined as a multiple of 6 resource blocks from the frequency domain to the carrier bandwidth.

The first CORESET is indicated through the MIB as part of the initial bandwidth part configuration to receive additional configuration information and system information from the network. After establishing a connection with the base station, the terminal may receive and configure one or more CORESET information through RRC signaling.

In this specification, frequency, frame, subframe, resource, resource block, region, band, subband, control channel, data channel, synchronization signal, various reference signals, various signals or various messages related to NR (New Radio) Can be interpreted as meaning used in the past or present or various meanings used in the future.

NR (New Radio)

As described above, the NR recently conducted in 3GPP has been designed to satisfy various QoS requirements required for each segmented and specific usage scenario as well as an improved data rate compared to LTE. In particular, as a representative usage scenario of NR, enhancement mobile BroadBand (eMBB), massive MTC (mMTC) and Ultra Reliable and Low Latency Communications (URLLC) have been defined, and as a method to satisfy the requirements for each usage scenario, it is flexible compared to LTE ( flexible) Frame structure design is required. Each usage scenario has different requirements for data rates, latency, reliability, and coverage. Accordingly, as a method for efficiently satisfying requirements for each use scenario through a frequency band constituting an arbitrary NR system, radio resource units based on different numerology (eg subcarrier spacing, subframe, TTI, etc.) ( It is designed to efficiently multiplex units).

For example, a discussion on a method of multiplexing and supporting TDM, FDM or TDM / FDM based on one or multiple NR component carriers for numerology having different subcarrier spacing values is made. lost. In addition, discussions have been made on a method of supporting one or more time units in configuring a scheduling unit in a time domain. In this regard, NR defines a subframe as a type of time domain structure. As a reference numerology for defining the subframe duration, it was decided to define a single subframe duration consisting of 14 OFDM symbols of normal CP overhead based on 15 kHz SCS (Sub-Carrier Spacing), which is the same as LTE. Accordingly, the subframe in NR has a time duration of 1 ms. However, unlike LTE, the subframe of NR is an absolute reference time duration, and slots and mini-slots may be defined as time units based on actual uplink / downlink data scheduling. In this case, the number of OFDM symbols constituting the slot and the y value are determined to have a value of y = 14 regardless of the SCS value in the case of a normal CP.

Accordingly, an arbitrary slot is composed of 14 symbols. In addition, all symbols may be used for DL transmission, or all symbols may be used for UL transmission, or may be used in the form of DL portion + (gap) + UL portion depending on the transmission direction of the corresponding slot. have.

Also, in any numerology (or SCS), a mini-slot is defined consisting of fewer symbols than the aforementioned slots. A short-length time-domain scheduling interval for transmitting / receiving mini-slot-based uplink / downlink data may be set, or a long length time-domain scheduling interval for transmitting / receiving uplink / downlink data through slot aggregation may be configured. have. In particular, when transmitting / receiving latency-sensitive data such as URLLC, it is difficult to satisfy latency requirements when scheduling in 1 ms (14 symbols) based slots defined in a numerology-based frame structure with a small SCS value such as 15 kHz. You can. Therefore, a mini-slot defined with a smaller number of OFDM symbols than a slot composed of 14 symbols can be defined, and scheduling based on this can satisfy the requirements of URLLC.

8 is a diagram for exemplarily illustrating symbol level alignment between different SCSs in a radio access technology to which the present embodiment can be applied.

Referring to FIG. 8, as described above, numerology having different SCS values in one NR carrier can be multiplexed and supported by TDM and / or FDM. Accordingly, a method of scheduling data according to latency requirements based on a slot (or mini-slot) length defined for each numerology is also considered. For example, when the SCS is 60 kHz, the length of the symbol is reduced to about 1/4 compared to the case of the SCS 15 kHz, so if one slot is composed of 14 OFDM symbols, the corresponding 15 kHz based slot length is 1 ms. On the other hand, the slot length based on 60 kHz is reduced to about 0.25 ms.

LTE V2X communication

9 is a view for explaining the type of vehicle communication to which the present embodiment can be applied.

Referring to FIG. 9, a vehicle can be connected to the Internet and other vehicles by providing the vehicle with access to a mobile communication network (eg, LTE or LTE-Advanced). V2X (Vehicle to Everything) communication includes the following four types.

-V2V (Vehicle to Vehicle) Communication: Vehicle to vehicle communication

-V2I (Vehicle to Infrastructure) Communication: Communication between vehicle and infrastructure

-V2N (Vehicle to Network) Communication: Communication between vehicle and network

-V2P (Vehicle to Pedestrian) Communication: Communication between vehicle and pedestrian

10 exemplarily illustrates the architecture of a V2X communication system in an LTE system.

Referring to FIG. 10, V2X service may be provided through a PC5 interface and / or a Uu interface. Support through the PC5 interface was provided through V2X sidelink communication.

Specifically, a PC5 interface is connected between various V2X communication terminals (UE A to D), and the V2X communication terminal and the V2X control function are connected to the V3 interface. In addition, the V2X application server and the V2X application of each V2X communication terminal are linked with a V1 interface. The V2X communication terminal is connected to the base station (E-UTRAN) through the Uu interface, and the base station is connected to the core network (MME and S / P GW) and the S1 interface. MME and S / P GW are linked to HSS and S6a interfaces, and HSS is linked to V2X control functions and V4 interfaces. The core network entity is linked to the V2X application server and the SGi interface. Meanwhile, the V2X applications of each V2X communication terminal are linked to each other through a V5 interface.

In this LTE system, a wireless channel and a radio protocol design for direct link (ie, sidelink) transmission and reception between terminals have been made to provide direct communication and V2V services between terminals.

The user plane details of the conventional sidelink communication are as follows.

-There is no HARQ feedback for sidelink communication

-RLC UM is used for sidelink communication (RLC UM is used for sidelink communication)

-The receiving terminal needs to maintain at least one RLC UM entity per peered transmitting terminal (A receiving UE needs to maintain at least one RLC UM entity per transmitting peer UE)

-Receiving RLC UM entity used for sidelink communication does not need to be configured before receiving the first RLC UMD PDU (A receiving RLC UM entity used for sidelink communication does not need to be configured prior to reception of the first RLC UMD PDU)

-ROHC Unidirectional Mode is used for header compression in PDCP for sidelink communication

In summary, in the LTE technology, sidelink transmission and reception for providing V2X service was performed based on broadcast. Before performing V2X communication, the transmitting and receiving terminal did not need to establish a logical connection. Sidelink communication only supported RLC UM mode, which is useful for delay-sensitive services. Before the receiving terminal receives the first RLC UM PDU, the receiving RLC UM entity need not be configured. The receiving terminal needed to maintain at least one RLC UM entity for each transmitting terminal, and could receive the first RLC UM PDU to set the receiving RLC UM entity and process the received data.

NR V2X communication

3GPP is conducting research to support advanced V2X services such as vehicles platooning, extended sensors, advanced driving, and remote driving based on NR. NR V2X intends to support both sidelink unicast, sidelink groupcast, and sidelink broadcast methods. In addition, in order to provide the enhanced V2X service described above in NR V2X, it may be necessary to support lossless transmission. For this, it is necessary to support RLC AM (Acknowledged Mode) in sidelink communication that only supported RLC UM mode. However, a specific method for sidelink communication supporting RLC AM has not been disclosed.

Therefore, in LTE system based V2X communication, only RLC UM was supported, so there was a problem in that it was difficult to support enhanced V2X service through lossless transmission. have.

In this situation, the present disclosure intends to provide a highly reliable sidelink communication technology based on RLC AM. In particular, in the case of an RLC retransmission failure in RLC AM-based sidelink communication, a specific method for solving a problem that a service may be interrupted is proposed.

Each embodiment described below may be applied to an NR terminal through an NR base station. Alternatively, each embodiment may be applied to an LTE terminal through an LTE base station, or may be applied to an LTE terminal connecting to an eLTE base station connected through a 5G system (or 5G Core Network). Alternatively, each embodiment may be applied to an E-UTRAN NR Dual Connectivity (EN-DC) terminal or a NE-DC terminal that simultaneously provides LTE and NR radio connections.

In this specification, V2X communication may be described as side link communication or vehicle communication. In addition, the name of each information in the present specification is exemplary, and the information may be changed to various names by definitions of transmitting and receiving subjects and detailed data included in the information. Meanwhile, the terminal state may be divided into an RRC connection, an RRC idle state, and an RRC Inactive state. The RRC inactive state may be described as an RRC inactive state, and it is recognized that the corresponding terminal is in the RRC connection state between the core network and the base station, and means that the RRC connection is released between the base station and the terminal. That is, for the UE in the RRC inactive state, both the associated SRB and DRB are released, and the UE context is stored. In addition, the terminal in the RRC inactive state may have a state transition to the RRC connected state, and for this purpose, performs an RRC resume procedure.

In a conventional LTE system, sidelink transmission and reception for providing V2X service was performed based on broadcast. That is, a sidelink radio channel or radio signal is broadcast without specifying a receiving terminal at any transmitting terminal. Sidelink communication has been performed by receiving the broadcasting signals from nearby terminals.

However, in the case of NR V2X, a unicast method or a groupcast method needs to be supported. In this case, a unicast or groupcast link between one transmitting terminal and the corresponding receiving terminal (s), or one master terminal and the corresponding slave terminal (s) is configured. The PSSCH transmission resource through the configured link may also be scheduled by the base station or selected by the transmitting terminal, as described above.

Therefore, in order to provide an enhanced V2X service, when a unicast method or a groupcast method is supported, V2X communication can be performed using RLC AM providing lossless transmission.

Hereinafter, in order to facilitate understanding, description will be made based on unicast V2X communication. However, the present disclosure can be equally applied to V2X communication in a groupcast / multicast method as well as a unicast method. In addition, the present disclosure can be equally applied to any D2D communication provided in a unicast manner through a PC5 interface. For example, the present disclosure may be applied to a device supporting PC5 sidelink communication for Proximity-based services (ProSe) disclosed in 3GPP TS23.303 based on NR.

In addition, in this specification, various terms associated with a side link interface are described by adding a side link. For example, a radio bearer configured on a sidelink interface is described as a sidelink radio bearer, and RLC configuration information including RLC entity configuration information for the sidelink interface is described as sidelink RLC configuration information. However, this is to clarify the term and should be understood as information or a configuration entity for the side link even when the side link is not described. That is, the side link radio bearer configuration information and the radio bearer configuration information are used in the same sense when not specifically used to distinguish them. Similarly, the sidelink RLC configuration information and RLC configuration information are also used in the same sense.

11 is a diagram for describing a terminal operation according to an embodiment.

Referring to FIG. 11, a terminal performing vehicle communication (Vehicle to everything communication) receives sidelink radio bearing configuration information from a base station for configuring a side link radio bearing on a side link interface used for vehicle communication. It may be performed (S1100).

The terminal performs vehicle communication through a side link interface. Therefore, the terminal needs to configure the sidelink radio bearer on the sidelink interface. To this end, the terminal receives the sidelink radio bearer configuration information for the sidelink from the base station. The sidelink radio bearer configuration information may include RLC bearer configuration information. The RLC bearer configuration information may include parameters required to configure the AM RLC entity for the sidelink. For example, RLC bearer configuration information may include uplink AM RLC configuration information and downlink AM RLC configuration information. Here, the uplink refers to a link that transmits data from the perspective of the transmitting terminal to another terminal, and the downlink refers to a link that receives data from the other terminal from the perspective of the transmitting terminal. In addition, the sidelink radio bearer configuration information may include information for bidirectional AM RLC configuration. For example, the RLC bearer configuration information may include information for bidirectional AM RLC configuration.

The terminal may perform a step of configuring a sidelink radio bearer using a sidelink interface based on the sidelink radio bearer configuration information and transmitting the sidelink radio bearer configuration information to another terminal targeted for vehicle communication ( S1110).

For example, the terminal may inform the other terminal of the sidelink radio bearer parameters related to sidelink transmission and reception by instructing the sidelink radio bearer configuration information.

The terminal may configure the sidelink radio bearer based on the sidelink radio bearer configuration information before transmitting the sidelink radio bearer configuration information to another terminal. Alternatively, the terminal may configure the sidelink radio bearer based on the sidelink radio bearer configuration information after transmitting the sidelink radio bearer configuration information to another terminal.

For example, the terminal configures the AM RLC entity for the sidelink to the terminal using the sidelink radio bearer configuration information. In addition, the terminal may set a sidelink radio bearer configured on the sidelink interface for vehicle communication, and link with the configured AM RLC entity. One or more sidelink radio bearers may be configured, or may be configured for each V2X service.

The terminal may transmit and receive data to and from another vehicle communication terminal on the sidelink interface using the configured sidelink radio bearer. As described above, data may be transmitted and received in a unicast manner, but may also be transmitted and received in a groupcast or broadcast manner.

The terminal monitors the number of retransmissions of data transmitted through the sidelink radio bearer by the AM RLC entity linked to the sidelink radio bearer, and when the AM RLC entity associated with the sidelink radio bearer reaches the maximum number of retransmissions, the sidelink A step of detecting a radio link failure may be performed (S1120).

For example, because the vehicle communication data is transmitted and received through the AM RLC entity, the terminal receives an acknowledgment message for the transmitted data from another terminal. If an acknowledgment message (ex, ACK message) for specific transmission data is not received, the AM RLC entity of the terminal performs a retransmission operation. Therefore, the ARQ process is not applied in the vehicle communication based on the conventional LTE system, but the ARQ process operation for securing high reliability is applied in the vehicle communication of the present disclosure.

The AM RLC entity of the terminal monitors the number of retransmissions of transmission data transmitted through the sidelink radio bearer. This is because it is necessary to consider radio link failure when the transmission data is continuously retransmitted and the number of retransmissions for the specific transmission data is indicated by the base station or reaches a preset maximum number of retransmissions.

Therefore, the AM RLC entity of the terminal monitors and determines whether the number of retransmissions of the specific transmission data has reached the maximum number of retransmissions indicated or preset by the base station.

When the terminal detects a sidelink radio link failure because the number of retransmissions reaches the maximum number of retransmissions, the terminal may perform a step of instructing the detection of the sidelink radio link failure to the upper layer regardless of the RRC state (S1130).

The terminal recognizes that a problem has occurred in the corresponding sidelink when the number of retransmissions for the specific transmission data in the AM RLC entity reaches the maximum number of retransmissions indicated by the base station or preset. For example, the terminal may detect a radio link failure of the sidelink through which transmission data is transmitted. In this case, the terminal needs to request scheduling of a new sidelink radio resource from the base station when the base station allocates the sidelink radio resource. Or, the base station needs to be aware of the radio link failure of the sidelink for any reason.

To this end, if the number of retransmissions for a specific transmission data in the AM RLC entity of the terminal is reached by the base station or reaches a preset maximum number of retransmissions, the terminal may indicate this to the upper layer regardless of the RRC state of the terminal.

Meanwhile, when the RRC state of the terminal is the RRC connection state, the terminal may transmit information for indicating a sidelink radio link failure to the base station. For convenience of description, information for indicating a sidelink radio link failure is described as sidelink failure information, and there is no limitation on the terminology.

For example, the sidelink failure information includes at least one of serving cell identification information, serving cell measurement result information, sidelink carrier identification information, time stamp information, terminal location information, V2X session identification information, and destination L2 ID information. can do. Through this, the base station checks specific cell, carrier, time, location or session information related to the radio link failure situation of the sidelink reported by the terminal. If necessary, the base station may allocate new sidelink radio resources to the terminal.

As another example, the sidelink failure information may include sidelink RRC failure type information when the terminal is in the RRC connection state. The terminal in the RRC connection state can also transmit and receive data with the base station. Therefore, when the UE transmits radio link failure information to the base station, the base station may have difficulty in distinguishing whether the radio link failure is a radio link failure with the base station or a radio link failure for another carrier in a dual connectivity or CA situation. . Accordingly, when the terminal is in the RRC connection state, the terminal uses an RRC message distinguished from the RRC failure information message to distinguish sidelink failure information, or includes RRC failure type information for distinguishing sidelink failure information, sidelink ( Or, it may indicate that the sidelink radio link failure occurs due to the exceeded number of retransmissions in a specific radio bearer.

Meanwhile, the terminal may perform vehicle communication even in an RRC state other than the RRC connection state. That is, since vehicle communication directly transmits and receives data between a transmitting terminal and a receiving terminal regardless of a connection state with a base station, an RRC IDLE state or an RRC Inactive state terminal can also be performed.

Therefore, in the RRC IDLE state or RRC Inactive state, when the above-described AM RLC retransmission count reaches the maximum retransmission count, it is necessary to report sidelink failure information to the base station.

For example, the sidelink failure information may be transmitted to the base station through the RRC connection establishment procedure of the terminal when the terminal is in the RRC idle state or the RRC inactive state.

For example, when the terminal is in the RRC idle state, sidelink failure information may be transmitted to the base station in the process of establishing an RRC connection with the base station or after the RRC connection is established. If sidelink failure information is transmitted in the RRC connection establishment process, it may be included in an RRC setup request message, an RRC setup completion message, etc. that the UE transmits to the base station.

As another example, when the terminal is in the RRC Inactive state, sidelink failure information may be transmitted to the base station in the process of resuming the RRC connection for the terminal to transition to the RRC connection state or after the RRC connection is established. If sidelink failure information is transmitted in the RRC connection establishment process, it may be included in an RRC resume request message, an RRC resume complete message, etc. transmitted by the terminal to the base station.

Meanwhile, the sidelink identifier selected according to the configuration of the sidelink radio bearer may include at least one of sidelink radio bearer identification information, sidelink RLC bearer identification information, and sidelink logical channel identifier. In addition, the sidelink identifier can be selected by the terminal or another terminal.

For example, in configuring the sidelink radio bearer, the terminal may select and allocate the sidelink radio bearer identification information, the sidelink RLC bearer identification information, and the sidelink logical channel identifier.

As another example, in configuring the sidelink radio bearer, other terminals may select and allocate the sidelink radio bearer identification information, the sidelink RLC bearer identification information, and the sidelink logical channel identifier.

However, the sidelink identifier selected by the terminal or another terminal must be shared between the terminal and the other terminal, and must be recognized in the same sense. Therefore, the terminal and the other terminal can share the sidelink identifier.

On the other hand, when the terminal selects the sidelink identifier, the other terminal may have already allocated the identifier for other purposes or for sidelink communication with another third terminal. Therefore, a processing procedure is required in this case.

For example, when the selected sidelink identifier is an identifier being used by another terminal, the other terminal may transmit failure information to the base station or the sidelink identifier.

Meanwhile, the sidelink radio bearer configuration information may be received in a different procedure according to the RRC state of the terminal.

For example, when the UE is in the RRC connection state, sidelink radio bearer configuration information may be received according to a sidelink radio bearer request signal including QoS parameters of a V2X sidelink session that the UE transmits to the base station. For example, the terminal transmits a sidelink radio bearer request signal to the base station. The sidelink radio bearer request signal includes QoS parameters of the V2X sidelink session. The base station may transmit the sidelink radio bearer configuration information to the terminal based on the sidelink radio bearer request signal. If necessary, the sidelink radio bearer configuration information may be generated in association with QoS parameters of the V2X sidelink session.

As another example, when the UE is in an RRC idle state or an RRC Inactive state, sidelink radio bearer configuration information may be received through system information. That is, the base station can broadcast the system information by including sidelink radio bearer configuration information.

Through this operation, the terminal can perform AM RLC entity-based sidelink data transmission / reception operation without ambiguity, thereby supporting vehicle communication based on high reliability.

12 is a diagram for explaining an operation of a base station according to an embodiment.

Referring to FIG. 12, a base station controlling vehicle communication (Vehicle to everything communication) transmits sidelink radio bearing configuration information to a terminal for configuring a side link radio bearing on a side link interface used for vehicle communication. It may be performed (S1200).

The terminal performs vehicle communication through a side link interface. Therefore, the terminal needs to configure a side link radio bearer for performing vehicle communication. To this end, the base station transmits sidelink radio bearer configuration information to the terminal. The sidelink radio bearer configuration information may include RLC bearer configuration information. The RLC bearer configuration information may include parameters necessary for the UE to configure the AM RLC entity for the sidelink. For example, RLC bearer configuration information may include uplink AM RLC configuration information and downlink AM RLC configuration information. That is, the sidelink radio bearer configuration information may include RLC bearer configuration information including information for bidirectional AM RLC configuration.

The terminal transmits the sidelink radio bearer configuration information to another terminal targeted for vehicle communication. For example, the terminal may inform the other terminal of the sidelink radio bearer parameters related to sidelink transmission and reception by instructing the sidelink radio bearer configuration information. Meanwhile, the sidelink identifier selected according to the sidelink radio bearer configuration is side It may include at least one of link radio bearer identification information, sidelink RLC bearer identification information, and sidelink logical channel identifier. In addition, the sidelink identifier can be selected by the terminal or another terminal.

For example, in configuring the sidelink radio bearer, the terminal may select and allocate the sidelink radio bearer identification information, the sidelink RLC bearer identification information, and the sidelink logical channel identifier.

As another example, in configuring the sidelink radio bearer, other terminals may select and allocate the sidelink radio bearer identification information, the sidelink RLC bearer identification information, and the sidelink logical channel identifier.

However, the sidelink identifier selected by the terminal or another terminal must be shared between the terminal and the other terminal, and must be recognized in the same sense. Therefore, the terminal and the other terminal can share the sidelink identifier.

On the other hand, when the terminal selects the sidelink identifier, the other terminal may have already allocated the identifier for other purposes or for sidelink communication with another third terminal. Therefore, a processing procedure is required in this case.

For example, when the selected sidelink identifier is an identifier being used by another terminal, the other terminal may transmit failure information to the base station or the sidelink identifier.

Meanwhile, the terminal configures the AM RLC entity for the sidelink to the terminal using the sidelink radio bearer configuration information. In addition, the terminal may set a side link radio bearer for vehicle communication and link it to the configured side link AM RLC entity. One or more sidelink radio bearers may be configured, or may be configured for each V2X service.

Meanwhile, the sidelink radio bearer configuration information may be transmitted through a different procedure according to the RRC state of the terminal.

For example, when the terminal is in the RRC connection state, the sidelink radio bearer configuration information may be transmitted according to a sidelink radio bearer request signal including QoS parameters of a V2X sidelink session that the terminal transmits to the base station. For example, the base station receives the sidelink radio bearer request signal from the terminal. The sidelink radio bearer request signal includes QoS parameters of the V2X sidelink session. The base station may transmit the sidelink radio bearer configuration information to the terminal based on the sidelink radio bearer request signal. If necessary, the sidelink radio bearer configuration information may be generated in association with QoS parameters of the V2X sidelink session.

As another example, when the UE is in the RRC idle state or the RRC inactive state, sidelink radio bearer configuration information may be transmitted through system information. That is, the base station can broadcast the system information by including sidelink radio bearer configuration information.

The base station may perform a step of receiving sidelink failure information from the terminal, which occurs when the number of retransmissions of the transmission data in the AM RLC entity configured in the terminal reaches the maximum number of retransmissions based on the sidelink radio bearer configuration information ( S1210).

For example, the terminal configures the sidelink radio bearer based on the sidelink radio bearer configuration information, and the number of retransmissions of data transmitted through the sidelink radio bearer in the AM RLC entity linked to the sidelink radio bearer reaches the maximum number of retransmissions. Can detect.

When the number of retransmissions for a specific transmission data in the AM RLC entity of the terminal reaches the maximum number of retransmissions indicated by the base station or the terminal, the terminal recognizes that a problem has occurred in the corresponding sidelink. For example, the terminal may detect a radio link failure of the sidelink through which transmission data is transmitted. In this case, the base station needs to allocate a new radio resource to the terminal for the sidelink radio resource where the radio link failure is detected. Or, the base station needs to be aware of the radio link failure of the sidelink for any reason.

To this end, the base station receives sidelink failure information when the number of retransmissions for specific transmission data in the AM RLC entity of the terminal reaches the maximum retransmission number indicated by the base station or preset.

For example, the sidelink failure information includes at least one of serving cell identification information, serving cell measurement result information, sidelink carrier identification information, time stamp information, terminal location information, destination L2 ID information, and V2X session identification information. can do. Through this, the base station checks specific cell, carrier, time, location or session information related to the radio link failure situation of the sidelink reported by the terminal. If necessary, the base station may allocate new sidelink radio resources to the terminal.

As another example, the sidelink failure information may include sidelink RRC failure type information when the terminal is in the RRC connection state. The terminal in the RRC connection state can also transmit and receive data with the base station. Therefore, when the UE transmits radio link failure information to the base station, the base station may have difficulty in distinguishing whether the radio link failure is a radio link failure with the base station or a radio link failure for another carrier in a dual connectivity or CA situation. . Accordingly, when the UE is in the RRC connection state, the UE uses an RRC message distinct from the RRC failure information message to distinguish sidelink failure information or transmits RRC failure type information that distinguishes sidelink failure information. The base station may obtain information on the type of the failure by receiving sidelink failure information including RRC failure type information indicating that the sidelink is failed due to exceeding the number of retransmissions in the sidelink (or a specific radio bearer).

Meanwhile, the terminal may perform vehicle communication even in an RRC state other than the RRC connection state. That is, since vehicle communication directly transmits and receives data between a transmitting terminal and a receiving terminal regardless of a connection state with a base station, an RRC IDLE state or an RRC Inactive state terminal can also be performed.

Therefore, in the RRC IDLE state or RRC Inactive state, when the above-described AM RLC retransmission count reaches the maximum retransmission count, the base station needs to receive sidelink failure information in order to recognize the situation.

For example, the sidelink failure information may be received by the base station through the RRC connection establishment procedure of the terminal when the terminal is in the RRC idle state or the RRC inactive state.

For example, when the terminal is in the RRC idle state, sidelink failure information may be received by the terminal in the process of establishing an RRC connection with the base station or after the RRC connection is established. If sidelink failure information is received in the RRC connection setup process, the base station may receive the RRC setup request message, the RRC setup completion message, and the like.

As another example, when the terminal is in the RRC Inactive state, sidelink failure information may be received at the base station in the process of resuming the RRC connection for the terminal to transition to the RRC connection state or after the RRC connection is established. If sidelink failure information is transmitted during the RRC connection establishment process, the base station may receive the RRC resume request message, the RRC resume completion message, and the like.

Through this operation, the terminal can perform AM RLC entity-based sidelink data transmission / reception operation without ambiguity, thereby supporting vehicle communication based on high reliability.

Hereinafter, an embodiment of each detailed step that can be applied in controlling the above-described UE and base station to control the side link data transmission and reception operation based on the AM RLC entity will be described. The detailed embodiments described below may be performed in each step or in each configuration, and may be performed individually or in any combination.

In addition, the sidelink AM RLC entity below may refer to AM RLC configured to perform vehicle communication using the above-described sidelink interface. In addition, the sidelink AM RLC configuration information may mean the aforementioned RLC bearer configuration information, and may be included in the above-described sidelink radio bearer configuration information. Alternatively, the sidelink AM RLC configuration information may be described in the same meaning as the above-described sidelink radio bearer configuration information.

Sidelink AM RLC Configuration Example

1) For vehicle communication of the terminal, sidelink AM RLC configuration information for configuring the sidelink AM RLC entity may be configured in the terminal before performing vehicle communication.

For example, in order to support unicast V2X communication using an AM RLC entity, a terminal capable of V2X communication may configure an AM RLC entity providing an RLC AM function through a PC5 sidelink interface. AM RLC entity configuration information for the configuration of the AM RLC entity may be pre-configured in the terminal. For example, the sidelink AM RLC entity configuration information may include uplink AM RLC configuration information (ul-AM-RLC) and downlink AM RLC configuration information (dl-AM-RLC). The uplink AM RLC configuration information may include one or more information elements of sn-FieldLength, t-PollRetransmit, pollPDU, pollByte, and maxRetxThreshold. The downlink AM RLC configuration information may include one or more information elements of sn-FieldLength, t-Reassembly and t-StatusProhibit. As described above, the sidelink AM RLC configuration information may be included in the sidelink radio bearer configuration information. In addition, sidelink AM RLC configuration information may be included in sidelink RLC bearer configuration information of the sidelink radio bearer configuration information.

The transmitting and receiving terminal performing vehicle communication preconfigures the sidelink AM RLC configuration information before vehicle communication through the sidelink by transmitting the uplink AM RLC configuration information as the transmission AM RLC information and the downlink AM RLC configuration information as the reception AM RLC information. can do. Alternatively, a default value for each of the above-described information elements may be pre-configured in the terminal. For example, the maximum retransmission threshold may be preconfigured in the terminal. Both the transmitting terminal and the receiving terminal may be configured in advance with uplink AM RLC configuration information and downlink AM RLC configuration information. Alternatively, the transmitting terminal and the receiving terminal may configure the sidelink AM RLC entity in advance using the sidelink AM RLC configuration information. The sidelink AM RLC parameter between the transmitting and receiving terminals may be configured with the same value between the transmitting terminal and the receiving terminal. Through this, it is possible to perform matching processing between the transmitting terminal and the receiving terminal. For example, the maximum retransmission threshold (maxRetxThreshold) included in the transmission AM RLC configuration information of the transmitting terminal and the maximum retransmission threshold (maxRetxThreshold) included in the transmission AM RLC configuration information of the receiving terminal may be configured with the same value. . For another example, the sequence number length (sn-FieldLength) included in the transmission AM RLC configuration information of the transmitting terminal has the same value as the sequence number length (sn-FieldLength) included in the reception AM RLC configuration information of the receiving terminal. Can be.

2) For vehicle communication of the terminal, the sidelink AM RLC configuration information for configuring the sidelink AM RLC entity is composed of a plurality of sets having values with different detailed parameters, and each AM RLC configuration information is indexed. It can be divided and configured in the terminal.

The sidelink AM RLC configuration information may be pre-configured in the terminal by differently setting a value that the detailed information element can have for each detailed information element according to an operator policy. The index can be managed by linking each sidelink AM RLC configuration information having different detail element values. In addition, index information of the sidelink AM RLC configuration information may be first transmitted when initiating a unicast V2X communication (for example, when setting a sidelink radio bearer) to use the RLC AM function. For example, during the PC5 unicast link establishment procedure of the upper layer (e.g. NAS, V2X application layer), index information of AM RLC configuration information may be transmitted between the transmitting terminal and the receiving terminal. As another example, index information of sidelink AM RLC configuration information may be transmitted between a transmitting terminal and a receiving terminal during setting of the sidelink radio bearer through an RRC message.

3) Sidelink AM RLC configuration information may be pre-configured in connection with parameters related to vehicle communication.

For example, sidelink AM RLC configuration information linked to at least one of the following parameters may be preconfigured in the terminal.

-A source L2 ID for identifying a sender or a destination L2 ID for identifying a target in V2X sidelink communication

-Mapping information between V2X service / application layer and destination L2 ID

-Information for identifying the transmitting terminal in the V2X service / application layer

-Information for identifying the destination terminal in the V2X service / application layer

-Transmission profile of protocol data unit transmitted through PC5 interface provided / instructed by upper layer

-Priority / QoS parameters of the protocol data unit transmitted through the PC5 interface provided / instructed by the upper layer for processing logical channel prioritization of V2X sidelink communication: for example, PPPP, PPPR, PC5 5QI (PQI)

-PC5 5G QoS parameter

-allocation and retention priority

-GFBR (Guaranteed Flow Bit Rate)

-QoS information (maximum flow bit rate etc.)

-reflective QoS attribute

-Range displayed in meters

Each of the above parameters will be described in detail.

One or more sidelink radio bearers may be configured in one source L2 ID and one destination L2 ID. Within one source L2 ID and one destination L2 ID, one sidelink radio bearer can be identified through a sidelink radio bearer identifier for identifying it. The sidelink radio bearer may include RLC bearer configuration information like the NR Uu radio bearer. The RLC bearer configuration information of NR Uu includes a logical channel identifier, a radio bearer identifier, RLC configuration information, and logical channel configuration information. When the sidelink is applied to the RRC information element of the Uu of the NR as described above, the sidelink radio bearer identifier and the sidelink logical channel identifier can be configured by linking the sidelink RLC bearer configuration information.

The source / destination L2 ID indicates information included in the MAC header. For example, one part of the entire source / destination ID is used as the L1 source / destination ID in Sidelink Control Information (SCI), and the other part is carried as the source / destination L2 ID in the MAC header. The source / destination L2 ID is used to identify the source / destination of the corresponding L2 frame on the PC5 interface. The source L2 ID is always assigned by the terminal generating the corresponding L2 frame. In the initial signaling for the establishment of the PC5 unicast link in the upper layer, the default destination L2 ID associated with the V2X service type may be used. During the PC5 unicast link establishment procedure, the L2 ID is exchanged. And the source / destination L2 ID is used for the subsequent communication between the two terminals.

V2X service represents a service provided by a V2X application and a V2X application server. For example, the V2X service may be classified into different V2X service types with a provider service identifier (PSID) identifier or a ITS application identifier (ITS-AID) identifier provided by a service provider.

The V2X application layer identifier is associated with one or more V2X applications in the terminal. Since the V2X application layer does not use the L2 ID, the terminal maintains mapping information between the application layer ID and the source L2 ID used for the PC5 unicast link. For example, the V2X application layer identifier can be used as an identifier (ex, station ID, vehicle ID, etc.) to identify a specific object such as a vehicle, a pedestrian, or a road side unit (RSU) within the context of a specific V2X application. have.

PC5 QoS information is provided for PC5 unicast communication from the V2X application layer, and indicates PC5 QoS parameters for V2X services.

PQI is a special 5QI and represents a parameter for controlling QoS forwarding treatment for packets transmitted through the PC5 reference point.

PC5 Aggregated Bit Rates represents the aggregate maximum bit rate for PC5 links.

In NR-based PC5 unicast communication, a flow-based QoS model can be used similar to NR Uu. For example, the UE derives PC5 QoS parameters based on the V2X application layer and V2X application requirements provided by the V2X service type. The UE allocates a PC5 QoS Flow Identifier (PFI) to this PC5 QoS flow. And it derives PC5 QoS rules. The PC5 QoS rule includes an IP packet filter set or a V2X packet filter set. The V2X packet filter set may be supported based on a combination of V2X service type, source / destination L2 ID, application layer ID, and extended parameters.

As described above, since the P5 (PC5 QoS Flow Identifier) is allocated based on the V2X service type, the source L2 ID, the destination L2 ID, and the application layer ID, it is used in conjunction with the sidelink radio bearer, so the sidelink including the AM RLC entity The radio bearer or sidelink RLC bearer or sidelink logical channel identifier may be configured in connection with one or more of V2X service type, source L2 ID, destination L2 ID, application layer ID, 5QI (PQI) and PC5 5G QoS parameters.

On the other hand, when performing unicast data transmission through a V2X communication session, sidelink radio bearer identification information or sidelink RLC bearer identification information or sidelink logical channel identifier must be matched on the transmitting terminal and the receiving terminal. The side link corresponding to the transmitting / receiving terminal so that the transmitting / receiving terminal transmits and receives data by aligning at least one of the sidelink radio bearer parameter (identification information), the sidelink RLC bearer parameter (identification information), and the sidelink logical channel parameter (identifier) The above parameters for identifying the radio configuration must match. However, for convenience of description, sidelink radio bearer identification information, sidelink RLC bearer identification information, and sidelink logical channel identifiers are denoted as sidelink identifiers below.

The above-described sidelink identifier information should be matched on the transmitting terminal and the receiving terminal. However, there may be a case in which the sidelink identifier information included in the transmitting terminal for configuring the sidelink radio bearer is not allowed in the receiving terminal. For example, a sidelink radio bearer for performing data communication using a corresponding sidelink identifier information from another transmitting terminal while the receiving terminal is already in data communication with one transmitting terminal using specific sidelink identifier information. Configuration information can be received. In this case, the receiving terminal cannot use the corresponding sidelink identifier information.

To solve this, you can use the following method. In the following, in order to classify the terminals from the viewpoint of transmission and reception, it may be described by describing the aforementioned terminal as a transmitting terminal and another terminal as a receiving terminal.

In one method, the transmitting terminal transmits the sidelink radio bearer configuration information including the sidelink identifier information set information available on the RRC message for configuring the sidelink radio bearer at the transmitting terminal to the receiving terminal. In this case, the sidelink identifier information may be information selected by the transmitting terminal or selected by the base station. The receiving terminal may select applicable sidelink identifier information from among the received sets, and may transmit an RRC confirmation message including the selected sidelink identifier information to the transmitting terminal. The receiving terminal may select any sidelink identifier information among the set of available sidelink identifier information, or may select identifier information having the smallest value.

Alternatively, the transmitting terminal transmits the sidelink radio bearing configuration information including side link identifier information selected by the transmitting terminal among the set of side link identifier information available on the RRC message for configuring the side link radio bearing in the transmitting terminal. The receiving terminal may transmit an RRC confirmation message for the sidelink identifier information selected by the transmitting terminal, if applicable. If the sidelink identifier information selected by the transmitting terminal at the receiving terminal is already occupied and is not applicable, the RRC failure / response message for this may include the sidelink identifier information set information available at the receiving terminal and transmit it to the transmitting terminal. have. Alternatively, in the case of a connected state terminal, an RRC failure / response message may be transmitted to the base station. For example, the receiving terminal may transmit an RRC failure / response message to the base station. For another example, the receiving terminal transmits an RRC failure / response message to the transmitting terminal, and the transmitting terminal may transmit it to the base station. When the sidelink identifier assigned by the base station or selected by the transmitting terminal is transmitted to the receiving terminal as described above, the sidelink identifier can be applied through negotiation with the receiving terminal. Alternatively, upon request of the transmitting terminal or the receiving terminal, the opposite terminal can check and apply the sidelink identifier. Alternatively, if the sidelink identifiers are duplicated, it is determined that it is a failure, and the receiving terminal (or the opposite terminal) can transmit the indication information to the transmitting terminal or the base station. For example, when a transmitting terminal initiating unicast sidelink communication has set a sidelink wireless bearer or transmits it to the receiving terminal, the receiving terminal knows this, but the receiving terminal does not have a corresponding sidelink wireless bearer configuration (for example, sidelink) When the identifier is collided), it can be informed to the base station. For convenience of description, the sidelink identifier has been described, but the above-described method has arbitrary sidelink RRC parameters (logical channel configuration information, RLC configuration information, PDCP configuration information, SDAP configuration information).

Meanwhile, as an example, when the transmitting terminal initiates the unicast V2X communication using the RLC AM function, the receiving terminal may receive the first RLC AM PDU to set the receiving AM RLC entity. In the receiving terminal, the above-described parameters (source L2 ID, destination L2 ID, mapping information between the V2X service / application layer and destination L2 ID), information for identifying the transmitting terminal in the V2X service / application layer to identify the corresponding AM RLC entity, Information to identify the destination terminal at the V2X service / application layer, transmission profile of the V2X communication session provided / directed by the upper layer, priority / QoS parameter of the V2X communication session provided / directed by the upper layer), 5QI ( PQI), PC5 5G QoS parameter, sidelink radio bearer identification information, sidelink RLC bearer identification information and one or more of the sidelink logical channel identifiers) may be used.

As another example, a logical connection may be established through a PC5 sidelink interface between two terminals for unicast V2X communication using the RLC AM function. For convenience of description, a connection through a direct interface (PC5 interface) between terminals is described below as a logical connection. This is for convenience of description and can be replaced with any name. The logical connection may be a logical connection between terminals on the AS similar to the RRC connection, a logical connection between terminals at a higher layer such as PC5 signaling, or a logical connection between terminals at the application layer. have.

If a logical connection is established through PC5 signaling, the transmitting terminal that wants to perform unicast V2X communication transmits a PC5 signaling message for requesting V2X direct communication to the receiving terminal. The PC5 signaling message may include the above-described AM RLC configuration information. The PC5 signaling message includes source L2 ID, destination L2 ID, mapping information between the V2X service / application layer and destination L2 ID, information for identifying the transmitting terminal in the V2X service / application layer, and identifying the destination terminal in the V2X service / application layer. Information, transmission profile of the V2X communication session provided / directed by the upper layer, priority / QoS parameter of the V2X communication session provided / directed by the upper layer, 5QI (PQI), PC5 5G QoS parameter, sidelink radio bearer Identification information, sidelink RLC bearer identification information, sidelink logical channel identifier, SDAP configuration information for a corresponding V2X communication session, and PDCP configuration information may include one or more configuration information. The receiving terminal may configure a corresponding AM RLC entity and other L2 entities (PDCP entity, SDAP entity) associated with the configuration information.

If a logical connection is established through AS (or RRC) signaling, the transmitting terminal wishing to perform unicast V2X communication transmits an RRC signaling message for configuring V2X direct communication to the receiving terminal. The RRC signaling message may include the aforementioned AM RLC configuration information. The RRC signaling message includes source L2 ID, destination L2 ID, mapping information between the V2X service / application layer and destination L2 ID, information for identifying the transmitting terminal in the V2X service / application layer, and identifying the destination terminal in the V2X service / application layer. Information, transmission profile of the V2X communication session provided / directed by the upper layer, priority / QoS parameter of the V2X communication session provided / directed by the upper layer, 5QI (PQI), PC5 5G QoS parameter, sidelink radio bearer Identification information, sidelink RLC bearer identification information, sidelink logical channel identifier, SDAP configuration information for a corresponding V2X communication session, and PDCP configuration information may include one or more configuration information. The receiving terminal may configure the corresponding AM RLC entity and other L2 entities (PDCP entity, SDAP entity) associated with the configuration information. Here, the SDAP configuration information includes information for mapping a corresponding QoS flow to a sidelink radio bearer similar to NR. For example, SDAP configuration information included in the sidelink radio bearer configuration information may include PFI information. For example, the SDAP configuration information included in the sidelink radio bearer configuration information may include one or more information of a V2X service type, a source L2 ID, a destination L2 ID, and an application layer ID linked to PFI information. Through this, a side link data radio bearer can be set. When the UE establishes a logical connection through PC5 signaling of the upper layer, the upper layer of the UE informs the RRC. When the terminal establishes a logical connection through PC5 signaling of a higher layer, the RRC of the terminal may perform an RRC signaling transmission operation on the sidelink interface. If the logical connection is released through PC5 signaling of the upper layer, the upper layer of the terminal informs the RRC. The RRC can release the associated sidelink RRC connection and sidelink data radio bearer.

If a logical connection is established through V2X application signaling, the transmitting terminal to perform unicast V2X communication transmits an application layer signaling message for requesting V2X direct communication to the receiving terminal. The application layer signaling message may include the above-described AM RLC configuration information. The application layer signaling message includes source L2 ID, destination L2 ID, mapping information between the V2X service / application layer and destination L2 ID, information for identifying the transmitting terminal in the V2X service / application layer, and identifying the destination terminal in the V2X service / application layer. Information to do, transmission profile of a V2X communication session provided / directed by a higher layer, priority / QoS parameter of a V2X communication session provided / directed by a higher layer, 5QI (PQI), PC5 5G QoS parameter, sidelink radio It may include one or more configuration information of bearer identification information, sidelink RLC bearer identification information, sidelink logical channel identifier, SDAP configuration information for a corresponding V2X communication session, and PDCP configuration information. The receiving terminal may configure the corresponding AM RLC entity and other L2 entities (PDCP entity, SDAP entity) associated with the configuration information.

Meanwhile, the above-described signaling (PC5, AS, RRC, or application layer signaling) may be directed to the terminal through a network (e.g. base station).

As an example, the transmitting terminal requests the network through the Uu interface, and the network can transmit signaling including the sidelink radio bearer configuration information including the above-described sidelink AM RLC configuration information to the receiving terminal through the Uu interface. The receiving terminal may configure the sidelink AM RLC entity and other associated L2 entities (PDCP entity, SDAP entity) based on the sidelink AM RLC configuration information received by the network. Through this, the receiving terminal may configure the sidelink radio bearer by receiving the configuration information of the sidelink radio bearer.

As another example, a transmitting terminal may request sidelink radio bearer configuration information including sidelink AM RLC configuration information to a network through a Uu interface. The network transmits signaling including sidelink radio bearer configuration information including sidelink AM RLC configuration information to a transmitting terminal through a Uu interface. The transmitting terminal may configure the sidelink AM RLC entity and other associated L2 entities (PDCP entity, SDAP entity) based on the received sidelink AM RLC configuration information. The transmitting terminal instructs signaling including sidelink AM RLC configuration information to the receiving terminal through the PC5 interface. The receiving terminal may configure a corresponding sidelink AM RLC entity and other associated L2 entities (PDCP entity, SDAP entity) based on the sidelink AM RLC configuration information. As such, the transmitting terminal may receive the sidelink radio bearer configuration information through the network. The transmitting terminal may transmit the sidelink radio bearer configuration information received through the network to the receiving terminal. The receiving terminal may configure the sidelink radio bearer by receiving the sidelink radio bearer configuration information.

The above-described method can be applied to the configuration of the sidelink radio bearer of the RRC connected state terminal. For example, through the RRC-only message, the transmitting terminal may perform sidelink communication by receiving sidelink radio bearer configuration information through a network and transmitting it to the receiving terminal.

Meanwhile, a terminal in an RRC IDLE state or an RRC Inactive state can also perform sidelink communication. To this end, the RRC IDLE state or RRC Inactive state terminal may receive sidelink radio bearer configuration information through a network through system information. For example, the transmitting terminal may receive side link radio bearer configuration information transmitted as system information through a network. The transmitting terminal may transmit the sidelink radio bearer configuration information received through the system information to the receiving terminal. The receiving terminal may configure the side link radio bearer by receiving the corresponding information. For another example, the transmitting terminal may receive sidelink radio bearer configuration information transmitted as system information through a network. The transmitting terminal may transmit the sidelink radio bearer configuration information received through the system information to the receiving terminal. For example, the transmitting terminal may receive side link radio bearer configuration information transmitted as system information through a network. The receiving terminal may configure a side link radio bearer when the information received from the transmitting terminal and the information received through the system information are the same. For another example, the network may indicate information for indicating an arbitrary operation for the above-described embodiment to the terminal through system information (or RRC-only message). The above-described embodiment may also be applied to an RRC connected state terminal.

Although described above as the AM RLC configuration information, the sidelink AM RLC configuration information may be included in the sidelink radio bearer configuration information as described above. Therefore, the contents described above with the AM RLC configuration information can be replaced with the sidelink radio bearer configuration information.

Processing method when the maximum retransmission is reached in the sidelink AM RLC entity

When the terminal in the RRC connection state reaches the maximum number of retransmissions in the AM RLC entity, RLF (Radio Link Failure) is detected. The operation at the time of detection of the maximum retransmission between the terminal and the base station will be described.

For example, the maximum number of retransmissions has been reached for an SRB or for an MCG or split DRB for an SRB or MCG DRB or split DRB from an MCG RLC entity. When detected, the RLC entity indicates this to the RRC layer, and the RRC considers the MCG radio link failure. In the case of radio link failure for MCG, when the UE detects RLF, it stores RLF information in VarRLF-Report. If AS security is not activated, the terminal releases the RRC Connected state. That is, the terminal transitions to the RRC IDLE state. Alternatively, when AS security is activated, the terminal performs an RRC connection re-establishment procedure.

For another example, when the maximum number of retransmissions is detected from the SCG RLC entity, the RLC entity indicates this to the RRC layer and the RRC considers it as an SCG radio link failure. And the terminal instructed the SCG radio link failure to the base station through the SCG failure information procedure. The UE transmits the failure type (failuretype) to the RRC message (SCGFailureInformationNR message) transmitted to the base station as information (rlc-MaxNumRetx) for indicating that the SCG RLC has reached the maximum retransmission.

Hereinafter, an embodiment of detecting a radio link failure in vehicle communication supporting the RLC AM function will be described in detail.

1. In the case of RRC IDLE / Inactive, an embodiment in which logging of the maximum retransmission of the side link is performed

V2X communication may be performed not only in the RRC connected state terminal but also in the RRC idle / inactive state terminal.

The terminal in the RRC idle / inactive state can perform unicast V2X communication using the RLC AM function through the PC5 interface. If the maximum number of retransmissions for a specific radio bearer is detected from the sidelink communication RLC entity, the sidelink RLC entity may indicate this to the RRC (or any upper layer or PC5 RRC or PC5-Signalling layer). Alternatively, the sidelink RLC entity may inform the PC5 RRC and indicate it to the PC5-Signalling layer in the PC5 RRC. The UE in the RRC idle / inactive state can record a log of the failure to reach the sidelink maximum RLC retransmission. Corresponding logging includes cause information, RRC IDLE / serving cell identifier of inactive terminal (servCellIdentity or physical cell identifier), SSB frequency, serving cell measurement result (measResultServCell), cell level measurement result based on SS / PBCH related measurement, SS / Beam level measurement result based on PBCH related measurement, cell level measurement result based on CSI-RS related measurement, beam level measurement result based on CSI-RS related measurement, measurement type (SS / PBCH or CSI-RS, cell level or beam level) ), Carrier identifier performing side link communication, carrier frequency, TX resource pool, RX resource pool, measurement result of the corresponding carrier, time to reach the maximum RLC retransmission of the side link (eg timestamp or elapsed time since the start of the session), location information And information for identifying a V2X communication session through a corresponding sidelink.

In addition, information for identifying a V2X communication session through the corresponding sidelink includes a source L2 identifier, a destination L2 identifier, a source IP address, a destination IP address, information for identifying a source terminal, information for identifying a destination terminal, and an application identifier , Identification information for identifying a specific service / session number of the application, V2X service type, V2X application layer identifier, 5QI (PQI), PC5 5G QoS parameter, PFI, sidelink radio bearer identification information, sidelink RLC bearer identification information And sidelink logical channel identifiers.

To this end, the base station may transmit information instructing the UE to perform a corresponding logging (or logged measurement) operation in the RRC IDLE / Inactive state to the UE. Information for instructing to perform the logging operation may be delivered through system information or dedicated signaling. The information for instructing to perform the logging operation may include configuration information necessary for the terminal to perform the logging operation.

Thereafter, when the RRC IDLE / inactive terminal establishes the RRC connection and enters the RRC connection state (or in the process of establishing the RRC connection or in the RRC connection state), logging information logged to the terminal (or indicating that the corresponding logging information is available) Information) to the base station. If the information for indicating that the logging information is available is transmitted to the base station, the base station may transmit a separate signaling instructing the terminal to transmit the logged logging information to the terminal. Upon receiving a separate signaling, the terminal may transmit logging information to the base station.

2. In the RRC IDLE / INACTIVE state, an embodiment in which connection establishment through the Uu interface is performed to transmit sidelink failure information according to the maximum number of retransmissions

V2X communication may be performed not only in the RRC connected state terminal but also in the RRC idle / inactive state terminal.

The terminal in the RRC idle / inactive state can perform unicast V2X communication using the RLC AM function through the PC5 interface. If the maximum number of retransmissions for a specific radio bearer is detected from the sidelink communication RLC entity, the sidelink RLC entity may indicate this to the RRC (or any upper layer or PC5 RRC or PC5-Signalling layer). Alternatively, the sidelink RLC entity may inform the PC5 RRC and indicate it to the PC5-Signalling layer in the PC5 RRC.

When the number of retransmissions in the sidelink RLC entity reaches the maximum number of retransmissions, the terminal in the RRC idle / inactive state establishes an RRC connection to configure the associated V2X communication session through the network (or for any other reason, such as reporting). Should be set. To this end, the terminal may transition to the RRC connection state. For example, in order to classify the priority of the RRC connection setting of the terminal to perform access control, the cause of the RRC setting of the conventional NR (ex, emergency, highPriorityAccess, mt-Access, mo-Signalling, mo-Data, mo -RRC connection can be configured to include a new setting cause or operator-defined setting cause different from VoiceCall, mo-VideoCall, mo-SMS, mps-PriorityAccess, and mcs-PriorityAccess). For another example, the UE may establish an RRC connection using one of the causes of RRC establishment in the conventional NR.

As a V2X Control function that provides parameters necessary to use V2X communication as a terminal, the terminal (upper layer of the terminal) can transmit sidelink failure information according to the maximum retransmission of the sidelink RLC (via the V3 interface).

Alternatively, the terminal (upper layer of the terminal) may transmit sidelink failure information according to the maximum retransmission of the sidelink RLC to the V2X application server (via the V1 interface).

Alternatively, the terminal may transmit sidelink failure information according to the arrival of the sidelink RLC maximum retransmission to the base station through the Uu interface.

Alternatively, the terminal (the upper layer of the terminal) may transmit sidelink failure information according to the arrival of the sidelink RLC maximum retransmission to the core network entity (eg, AMF).

The sidelink failure information according to the arrival of the sidelink RLC maximum retransmission may include at least one of the following information.

-Cause information

-RRC IDLE terminal serving cell identifier (servCellIdentity)

-SSB frequency

-Measurement result of serving cell (measResultServCell)

-Cell level measurement result based on SS / PBCH related measurement

-Beam level measurement result based on SS / PBCH related measurement

-Cell level measurement results based on CSI-RS related measurements

-Beam level measurement result based on CSI-RS related measurement

-Measurement type (SS / PBCH or CSI-RS, cell level or beam level)

-Carrier identifier performing side link communication

-Carrier frequency

-TX Resource Pool

-RX Resource Pool

-Measurement results of the carrier

-Time to reach the sidelink maximum RLC retransmission (e.g. timestamp)

-Elapsed time

-Location information

-Information for identifying a V2X communication session through the corresponding sidelink: source L2 identifier, destination L2 identifier, source IP address, destination IP address, information for identifying the source terminal, information for identifying the destination terminal, application identifier, Identification information to identify a specific service / session number of the application, V2X service type, V2X application layer identifier, 5QI (PQI), PC5 5G QoS parameter, PFI, sidelink radio bearer identification, sidelink RLC bearer identification and side Contains information on at least one of the link logical channel identifiers.

The transmitting terminal may configure a V2X communication session through the network and the receiving terminal of the sidelink failure to transmit and receive data. That is, the transmitting terminal may resume the suspended sidelink V2X communication session through the V2X communication session through the network.

3. An embodiment of switching a sidelink radio bearer when a terminal in an RRC connection state reaches the maximum number of retransmissions of sidelink communication RLC

1) First detailed embodiment

The UE in the RRC connected state can perform unicast V2X communication using the RLC AM function through the PC5 interface. If the maximum number of retransmissions for a specific radio bearer is detected from the sidelink communication RLC entity, the sidelink RLC entity may indicate this to the RRC (or any upper layer or PC5 RRC or PC5-Signalling layer). Alternatively, the sidelink RLC entity may inform the PC5 RRC and indicate it to the PC5-Signalling layer in the PC5 RRC.

The RRC of the terminal may transmit sidelink failure information to the base station through an uplink RRC message. The UE may transmit a failure message (failuretype) by setting the sidelink RLC to the maximum number of retransmissions. Through this, the base station can recognize the problem on the sidelink communication.

The base station that recognizes the arrival of the maximum number of retransmissions of the sidelink communication RLC may instruct the terminal to switch the V2X communication through the corresponding sidelink to the V2X communication through the network (or through the Uu interface). Alternatively, the terminal may switch V2X communication through the sidelink to V2X communication through the network (or via the Uu interface) when the sidelink communication RLC maximum retransmission is reached. Configuration information necessary to perform a switching operation from the network may be pre-configured in the terminal.

The switching operation may refer to an operation connected between a terminal and a V2X control function or a terminal and a V2X application server through a network. Alternatively, the switching operation is based on the information received from the V2X control function or the V2X application server, and the terminal connects the V2X communication session through the network with the receiving terminal to perform a procedure for switching a sidelink V2X communication session to a V2X communication session through the network. It can mean doing. Alternatively, the switching operation is pre-connected through the network between the terminal and the V2X control function or the terminal and the V2X application server, or based on information received from the V2X control function or the V2X application server, the terminal establishes a V2X communication session through the receiving terminal and the network. While transmitting and receiving data through a sidelink V2X communication session in a pre-connected state, it may mean switching the sidelink V2X communication session to a V2X communication session through a network. For example, a switching operation may be indicated in a state in which a failed V2X communication session is configured in association with a sidelink RLC entity and a Uu RLC entity in one PDCP entity. For another example, a switching operation may be indicated in a state in which a failed V2X communication session is configured in association with a sidelink PDCP entity and a Uu PDCP entity in one SDAP entity.

The switching operation can be provided by switching the L2 entity of the V2X communication session via the sidelink to the L2 entity of the V2X communication session via the Uu interface, and can be switched at the PDCP or SDAP layer for lossless transmission. When a switching operation is performed to provide lossless transmission, the PDCP entity may perform retransmission for unidentified PDCP PDUs.

Configuration information required to perform / connect the switching of the V2X communication session at the PDCP layer or SDAP layer includes information for identifying the V2X communication session, priority / QoS parameters of the V2X communication session, V2X service / application layer and destination L2 ID Mapping information with, information for identifying the transmitting terminal in the V2X service / application layer, information for identifying the destination terminal in the V2X service / application layer, among the transmission profile of the V2X communication session through the sidelink, the source L2 ID and the destination L2 ID It may include at least one piece of information. Configuration information may be pre-configured in the terminal or may be received by the base station.

2) Second detailed embodiment

The UE in the RRC connected state can perform unicast V2X communication using the RLC AM function through the PC5 interface. If the maximum number of retransmissions for a specific radio bearer is detected from the sidelink communication RLC entity, the sidelink RLC entity may indicate this to the RRC (or any upper layer or PC5 RRC or PC5-Signalling layer). Alternatively, the sidelink RLC entity may inform the PC5 RRC and indicate it to the PC5-Signalling layer in the PC5 RRC.

The terminal may attempt to reset the corresponding V2X communication through any PC5 signaling procedure (e.g. discovery procedure, Layer2 link setup procedure, Layer2 link reset procedure, Layer2 link recovery procedure, etc.) through the sidelink. When the terminal detects that the maximum number of retransmissions performed for the radio bearer is detected from the sidelink communication RLC entity, the UE suspends the RLC entity. Alternatively, the PC5 RRC connection including the corresponding RLC entity is released. In signaling for reconfiguration of the PC5 unicast link, the transmitting terminal is the destination L2 ID, the source terminal information (the initiating UE's Application Layer ID) and the target UE's Application Layer corresponding to the sidelink radio bearer that declared the sidelink radio link failure. ID) may include a PC5 signaling message (for example, a direct communication request message, a direct communication reset request broadcast message) for resetting the Layer2 link. The terminal includes information for identifying a V2X communication session, priority / QoS parameters of the V2X communication session, mapping information between the V2X service / application layer and the destination L2 ID, information for identifying a transmitting terminal in the V2X service / application layer, and V2X service / Attempt to recover V2X communication by using one or more of information for identifying the destination terminal in the application layer, the transmission profile of the V2X communication session through the sidelink, and the source L2 ID and destination L2 ID. In order to limit discovery / reset / recovery / PC5 signaling attempts, maximum transmission count information for any PC5 signaling signal such as discovery / reset / recovery may be preconfigured or configured by a network. When the corresponding switching is performed to provide lossless transmission, the PDCP entity may perform retransmission for unidentified PDCP PDUs.

The method of each embodiment described above can be applied to the RRC idle / inactive state terminal as well as the RRC connected state terminal. In addition, the method of each embodiment can be operated by any trigger rather than reaching the maximum number of retransmissions of the sidelink communication RLC. For example, a base station or a terminal may initiate a corresponding operation in consideration of the quality / load condition of a side link, and this is also included in the scope of the present disclosure.

Through the above-described operations, the present disclosure can provide an enhanced V2X service by supporting sidelink communication applying the RLC AM function. In addition, the present disclosure reduces the service interruption even when detecting sidelink radio failure due to RLC retransmission failure, and provides an effect of maintaining V2X communication.

Hereinafter, a configuration of a terminal and a base station capable of performing all or part of each of the above-described embodiments will be briefly described once again.

13 is a view for explaining a terminal configuration according to an embodiment.

Referring to FIG. 13, a terminal 1300 performing vehicle communication (Vehicle to everything communication) configures sidelink radio bearer configuration information for configuring a sidelink radio bearer on a sidelink interface used for vehicle communication. Based on the receiver 1330 and the sidelink radio bearer configuration information received from the base station, the sidelink radio bearer is configured, and when the AM RLC entity linked to the sidelink radio bearer reaches the maximum number of retransmissions, the sidelink radio It may include a control unit 1310 for detecting a link failure and a transmitting unit 1320 for transmitting the side link radio bearing configuration information to another terminal that is a vehicle communication target. When the sidelink radio link failure is detected, the controller 130 may control the sidelink radio link failure detection to be directed to the upper layer regardless of the RRC state of the terminal.

The reception unit 1330 receives the sidelink radio bearer configuration information from the base station. The sidelink radio bearer configuration information may include RLC bearer configuration information. The RLC bearer configuration information may include parameters required to configure the AM RLC entity for the sidelink. For example, RLC bearer configuration information may include information for bidirectional AM RLC configuration through uplink AM RLC configuration information and downlink AM RLC configuration information.

The control unit 1310 configures the AM RLC entity for the sidelink to the terminal using the sidelink radio bearer configuration information. In addition, the controller 1310 may set a side link radio bearer for vehicle communication and link it to the configured AM RLC entity. One or more sidelink radio bearers may be configured, or may be configured for each V2X service.

On the other hand, since the receiving unit 1330 transmits and receives vehicle communication data through the AM RLC entity, it receives an acknowledgment message for the transmitted data from the receiving terminal. If an acknowledgment message (ex, ACK message) for specific transmission data is not received, the AM RLC entity of the terminal 1300 performs a retransmission operation.

The control unit 1310 recognizes that a problem has occurred in the corresponding sidelink when the number of retransmissions for the specific transmission data in the sidelink AM RLC entity reaches the maximum number of retransmissions indicated by the base station or preset. For example, the terminal may detect a radio link failure of the sidelink through which transmission data is transmitted. In this case, the terminal needs to request scheduling of a new sidelink radio resource from the base station when the base station allocates the sidelink radio resource. Or, the base station needs to be aware of the radio link failure of the sidelink for any reason. To this end, if the number of retransmissions for a specific transmission data in the AM RLC entity of the terminal is reached by the base station or reaches a preset maximum number of retransmissions, the terminal may indicate this to the upper layer regardless of the RRC state of the terminal.

Alternatively, the transmitter 1320 may transmit sidelink failure information to the base station when the number of retransmissions for specific transmission data in the AM RLC entity of the terminal is indicated by the base station or reaches a preset maximum number of retransmissions.

For example, the sidelink failure information includes at least one of serving cell identification information, serving cell measurement result information, sidelink carrier identification information, time stamp information, terminal location information, destination L2 ID information, and V2X session identification information. can do. If necessary, the base station may allocate new sidelink radio resources to the terminal 1300. Or, the base station may instruct switching so that the V2X session is processed through the network.

As another example, the sidelink failure information may include sidelink RRC failure type information when the terminal 1300 is in an RRC connected state. The terminal 1300 in the RRC connection state can also transmit and receive data to and from the base station. Therefore, when the terminal 1300 is in the RRC connection state, the transmitter 1320 includes RRC failure type information indicating that the sidelink is failed due to exceeding the number of retransmissions in the sidelink (or a specific radio bearer) in the sidelink failure information. Can be transmitted.

Meanwhile, when the terminal 1300 is in an RRC idle state or an RRC inactive state, sidelink failure information may be transmitted to the base station through the RRC connection establishment procedure of the terminal 1300.

For example, when the terminal 1300 is in the RRC idle state, sidelink failure information may be transmitted to the base station in the process of the terminal 1300 establishing an RRC connection with the base station or after the RRC connection is established.

As another example, when the terminal 1300 is in the RRC Inactive state, sidelink failure information may be transmitted to the base station in the process of resuming the RRC connection for the terminal 1300 to transition to the RRC connection state or after the RRC connection is established.

Meanwhile, the sidelink identifier selected according to the configuration of the sidelink radio bearer may include at least one of sidelink radio bearer identification information, sidelink RLC bearer identification information, and sidelink logical channel identifier. In addition, the sidelink identifier may be selected by the terminal 1300 or another terminal.

For example, in configuring the sidelink radio bearer, the controller 1310 may select and allocate sidelink radio bearer identification information, sidelink RLC bearer identification information, and sidelink logical channel identifier.

As another example, in configuring the sidelink radio bearer, other terminals may select and allocate the sidelink radio bearer identification information, the sidelink RLC bearer identification information, and the sidelink logical channel identifier.

However, the sidelink identifier selected by the terminal 1300 or another terminal must be shared between the terminal (! 300) and another terminal, and must be recognized in the same sense. Therefore, the terminal and the other terminal can share the sidelink identifier.

On the other hand, when the terminal 1300 selects the sidelink identifier, the other terminal may have already allocated the identifier for other purposes or for sidelink communication with another third terminal. Therefore, a processing procedure is required in this case.

For example, when the selected sidelink identifier is an identifier being used by another terminal, the other terminal may transmit failure information to the base station or the sidelink identifier.

Meanwhile, the sidelink radio bearer configuration information may be received in another procedure according to the RRC state of the terminal 1300.

For example, when the terminal 1300 is in an RRC connected state, sidelink radio bearer configuration information may be received according to a sidelink radio bearer request signal including QoS parameters of a V2X sidelink session transmitted by the terminal 1300 to the base station. You can. For example, the transmitter 1320 transmits a sidelink radio bearer request signal to the base station. The sidelink radio bearer request signal includes QoS parameters of the V2X sidelink session. The base station may transmit the sidelink radio bearer configuration information to the terminal 1300 based on the sidelink radio bearer request signal. If necessary, the sidelink radio bearer configuration information may be generated in association with QoS parameters of the V2X sidelink session.

As another example, when the terminal 1300 is in an RRC idle state or an RRC inactive state, sidelink radio bearer configuration information may be received through system information. That is, the base station can broadcast the system information by including sidelink radio bearer configuration information.

In addition to this, the controller 1310 controls the operation of the overall terminal 1300 according to the AM RLC-based sidelink communication setup and sidelink failure processing operation required to perform the above-described embodiments.

In addition, the transmitter 1320 and the receiver 1330 are used to transmit and receive signals, messages, and data necessary to perform the above-described embodiments with base stations, other terminals, and respective entities on the V2X architecture.

14 is a diagram for explaining a configuration of a base station according to an embodiment.

Referring to FIG. 14, a base station 1400 for controlling vehicle to everything communication (V2X communication) configures side link radio bearers for configuring a side link radio bearer on a side link interface used for vehicle communication. Receiving sidelink failure information from the terminal, which is generated when the number of retransmissions of the transmission data in the AM RLC entity configured in the terminal reaches the maximum number of retransmissions, based on the transmitter 1420 and the sidelink radio bearer configuration information that transmits data to the terminal It may include a receiving unit 1430.

As described above, the sidelink radio bearer configuration information may include RLC bearer configuration information. The RLC bearer configuration information may include parameters necessary for the UE to configure the AM RLC entity for the sidelink. For example, RLC bearer configuration information may include information for bidirectional AM RLC configuration through uplink AM RLC configuration information and downlink AM RLC configuration information.

The terminal configures the AM RLC entity for the sidelink to the terminal using the sidelink radio bearer configuration information. In addition, the terminal may set a side link radio bearer for vehicle communication and link it to the configured AM RLC entity. One or more sidelink radio bearers may be configured, or may be configured for each V2X service.

Meanwhile, the terminal configures the sidelink radio bearer based on the sidelink radio bearer configuration information, and detects whether the number of retransmissions of data transmitted through the sidelink radio bearer reaches the maximum number of retransmissions in the AM RLC entity linked to the sidelink radio bearer. can do. When the number of retransmissions for a specific transmission data in the AM RLC entity of the terminal reaches a preset maximum number of retransmissions, the terminal recognizes that a problem has occurred in the corresponding sidelink.

When the number of retransmissions for a specific transmission data in the AM RLC entity of the terminal reaches a preset maximum retransmission number, the reception unit 1430 receives sidelink failure information from the terminal.

For example, the sidelink failure information includes at least one of serving cell identification information, serving cell measurement result information, sidelink carrier identification information, time stamp information, terminal location information, destination L2 ID information, and V2X session identification information. can do.

As another example, the sidelink failure information may include sidelink RRC failure type information when the terminal is in the RRC connection state. The control unit 1410 may obtain information on the type of failure by receiving sidelink failure information including RRC failure type information indicating that the sidelink is failed due to exceeding the number of retransmissions in the sidelink (or a specific radio bearer). .

In addition, when the terminal is in the RRC idle state or the RRC inactive state, the sidelink failure information may be received by the receiving unit 1430 through the RRC connection establishment procedure of the terminal.

For example, when the UE is in the RRC idle state, sidelink failure information may be received by the receiver 1430 in the process of establishing an RRC connection with the base station or after the RRC connection is established. As another example, when the terminal is in the RRC Inactive state, sidelink failure information may be received by the receiving unit 1430 in the process of resuming the RRC connection for the terminal to transition to the RRC connection state or after the RRC connection is established.

The terminal transmits the sidelink radio bearer configuration information to the other terminal that is the target of vehicle communication. For example, the terminal may inform the other terminal of the sidelink radio bearer parameters related to sidelink transmission and reception by instructing the sidelink radio bearer configuration information.

Meanwhile, the sidelink identifier selected according to the configuration of the sidelink radio bearer may include at least one of sidelink radio bearer identification information, sidelink RLC bearer identification information, and sidelink logical channel identifier. In addition, the sidelink identifier can be selected by the terminal or another terminal.

For example, in configuring the sidelink radio bearer, the terminal may select and allocate the sidelink radio bearer identification information, the sidelink RLC bearer identification information, and the sidelink logical channel identifier.

As another example, in configuring the sidelink radio bearer, other terminals may select and allocate the sidelink radio bearer identification information, the sidelink RLC bearer identification information, and the sidelink logical channel identifier.

However, the sidelink identifier selected by the terminal or another terminal must be shared between the terminal and the other terminal, and must be recognized in the same sense. Therefore, the terminal and the other terminal can share the sidelink identifier.

On the other hand, when the terminal selects the sidelink identifier, the other terminal may have already allocated the identifier for other purposes or for sidelink communication with another third terminal. Therefore, a processing procedure is required in this case.

For example, when the selected sidelink identifier is an identifier being used by another terminal, the other terminal may transmit failure information to the base station or the sidelink identifier. Accordingly, the reception unit 1430 may receive failure information from another terminal.

Meanwhile, the sidelink radio bearer configuration information may be transmitted through a different procedure according to the RRC state of the terminal.

For example, when the terminal is in the RRC connection state, the sidelink radio bearer configuration information may be transmitted according to a sidelink radio bearer request signal including QoS parameters of a V2X sidelink session that the terminal transmits to the base station. For example, the reception unit 1430 receives the sidelink radio bearer request signal from the terminal. The sidelink radio bearer request signal includes QoS parameters of the V2X sidelink session. The transmitter 1420 may transmit the sidelink radio bearer configuration information to the terminal based on the sidelink radio bearer request signal. If necessary, the sidelink radio bearer configuration information may be generated in association with QoS parameters of the V2X sidelink session.

As another example, when the UE is in the RRC idle state or the RRC inactive state, sidelink radio bearer configuration information may be transmitted through system information. That is, the transmitter 1420 may broadcast the system information including sidelink radio bearer configuration information.

In addition to this, the control unit 1410 controls the operation of the overall base station 1400 according to the AM RLC-based sidelink communication setup and sidelink failure processing operations required to perform the above-described embodiments.

In addition, the transmitter 1420 and the receiver 1430 are used to transmit and receive signals, messages, and data necessary to perform the above-described embodiments.

The above-described embodiments can be supported by standard documents disclosed in at least one of the wireless access systems IEEE 802, 3GPP and 3GPP2. That is, steps, components, and parts that are not described in order to clearly reveal the technical idea among the embodiments may be supported by the above-described standard documents. In addition, all terms disclosed in this specification may be described by standard documents disclosed above.

The above-described embodiments may be implemented through various means. For example, the embodiments may be implemented by hardware, firmware, software, or a combination thereof.

For implementation by hardware, the method according to the embodiments includes one or more Application Specific Integrated Circuits (ASICs), Digital Signal Processors (DSPs), Digital Signal Processing Devices (DSPDs), Programmable Logic Devices (PLDs), FPGAs (Field Programmable Gate Arrays), a processor, a controller, a microcontroller, or a microprocessor.

In the case of implementation by firmware or software, the method according to the embodiments may be implemented in the form of an apparatus, procedure, or function that performs the functions or operations described above. The software code can be stored in a memory unit and driven by a processor. The memory unit is located inside or outside the processor, and can exchange data with the processor by various known means.

In addition, the terms “system”, “processor”, “controller”, “component”, “module”, “interface”, “model”, or “unit” described above generally refer to computer-related object hardware, hardware and software. It can mean a combination of, software or running software. For example, the above-described components may be, but are not limited to, a processor driven process, a processor, a controller, a control processor, an object, an execution thread, a program, and / or a computer. For example, both an application running on a controller or processor and a controller or processor can be components. One or more components can be in a process and / or thread of execution, and the components can be located on one device (eg, a system, computing device, etc.) or distributed across two or more devices.

The above description is merely illustrative of the technical spirit of the present disclosure, and those skilled in the art to which the present disclosure pertains may make various modifications and variations without departing from the essential characteristics of the technical spirit. In addition, the present embodiments are not intended to limit the technical spirit of the present disclosure, but to explain the scope of the technical spirit of the embodiments. The scope of protection of the present disclosure should be interpreted by the claims below, and all technical spirits within the scope equivalent thereto should be interpreted as being included in the scope of the present disclosure.

Claims (24)

In the method for the terminal to perform vehicle communication (Vehicle to everything communication, V2X communication),
Receiving sidelink radio bearer configuration information for configuring a sidelink radio bearer on a sidelink interface used for vehicle communication from a base station;
Constructing a sidelink radio bearer based on the sidelink radio bearer configuration information, and transmitting the sidelink radio bearer configuration information to another terminal targeted for the vehicle communication;
Detecting a sidelink radio link failure when the AM RLC entity associated with the sidelink radio bearer has reached the maximum number of retransmissions; And
And detecting failure of the sidelink radio link, instructing the detection of the sidelink radio link failure to an upper layer regardless of the RRC state of the terminal. According to claim 1,
The side link radio bearing configuration information,
A method comprising RLC bearer configuration information including information for bidirectional AM RLC configuration. According to claim 1,
When the RRC state of the terminal is an RRC connection state,
And transmitting sidelink failure information according to the sidelink radio link failure detection to the base station. The method of claim 3,
The side link failure information,
Method comprising the destination L2 ID information. According to claim 1,
The sidelink identifier selected according to the configuration of the sidelink radio bearer includes at least one of sidelink radio bearer identification information, sidelink RLC bearer identification information, and sidelink logical channel identifier,
Method selected by the terminal or the other terminal. The method of claim 5,
When the selected sidelink identifier is an identifier being used by the other terminal,
The other terminal transmits the failure information to the base station. According to claim 1,
The sidelink radio bearer configuration information, characterized in that when the terminal is in an RRC connection state, is received according to a sidelink radio bearer request signal including QoS parameters of a V2X sidelink session transmitted to the base station. According to claim 1,
The sidelink radio bearer configuration information, characterized in that when the terminal is in an RRC idle state or an RRC Inactive state, is received through system information. In the method for the base station to control the vehicle communication (Vehicle to everything communication, V2X communication),
Transmitting sidelink radio bearer configuration information for configuring a sidelink radio bearer on a sidelink interface used for vehicle communication to a terminal; And
And receiving, from the terminal, sidelink failure information generated by the number of retransmissions of transmission data in the AM RLC entity configured in the terminal, based on the sidelink radio bearer configuration information, reaching the maximum number of retransmissions.
The terminal,
Configure the sidelink radio bearer using the sidelink interface based on the sidelink radio bearer configuration information,
A method of detecting whether the number of retransmissions of the transmitted data through the radio bearer reaches the maximum number of retransmissions in the AM RLC entity associated with the sidelink radio bearer. The method of claim 9,
The side link radio bearing configuration information,
Method for transmitting to the other terminal to the vehicle communication target through the terminal. The method of claim 9,
The side link radio bearing configuration information,
A method comprising RLC bearer configuration information including information for bidirectional AM RLC configuration. The method of claim 9,
The side link failure information,
Method comprising the destination L2 ID information. In the terminal performing a vehicle communication (Vehicle to everything communication, V2X communication),
A receiver configured to receive sidelink radio bearer configuration information for configuring a sidelink radio bearer on a sidelink interface used for vehicle communication from a base station;
On the basis of the sidelink radio bearer configuration information, configure a sidelink radio bearer,
A control unit that detects a sidelink radio link failure when the AM RLC entity associated with the sidelink radio bearer reaches a maximum number of retransmissions; And
And a transmitter for transmitting the sidelink radio bearing configuration information to another terminal targeted for the vehicle communication,
The control unit,
When the sidelink radio link failure is detected, the terminal to control the sidelink radio link failure detection is directed to the upper layer regardless of the RRC state of the terminal. The method of claim 13,
The side link radio bearing configuration information,
A terminal including RLC bearer configuration information including information for bidirectional AM RLC configuration. The method of claim 13,
The transmitting unit,
When the RRC state of the terminal is in this RRC connection state, the terminal transmitting the sidelink failure information according to the sidelink radio link failure detection to the base station. The method of claim 15,
The side link failure information,
A terminal comprising destination L2 ID information. The method of claim 13,
The side link identifier selected according to the configuration of the side link radio bearer,
Sidelink radio bearer identification information, sidelink RLC bearer identification information, and at least one of a sidelink logical channel identifier,
A terminal characterized by being selected by the terminal or the other terminal. The method of claim 17,
When the selected sidelink identifier is an identifier being used by the other terminal,
The other terminal is a terminal characterized in that for transmitting the failure information to the base station. The method of claim 13,
The side link radio bearing configuration information,
When the terminal is in the RRC connection, the terminal characterized in that it is received according to the sidelink radio bearer request signal including the QoS parameters of the V2X sidelink session to the base station. The method of claim 13,
The side link radio bearing configuration information,
When the terminal is in the RRC idle state or RRC Inactive state, characterized in that the terminal is received through the system information. In the base station for controlling the vehicle communication (Vehicle to everything communication, V2X communication),
A transmitter for transmitting sidelink radio bearing configuration information for configuring a side link radio bearing on a side link interface used for vehicle communication to a terminal; And
A receiver for receiving sidelink failure information from the terminal, which is generated when the number of retransmissions of transmitted data in the AM RLC entity configured in the terminal reaches the maximum number of retransmissions, based on the sidelink radio bearer configuration information,
The terminal,
Configure the sidelink radio bearer using the sidelink interface based on the sidelink radio bearer configuration information,
A base station that detects whether the number of retransmissions of the transmitted data through the radio bearer reaches the maximum number of retransmissions in the AM RLC entity associated with the sidelink radio bearer. The method of claim 21,
The side link radio bearing configuration information,
A base station characterized in that it is transmitted to another terminal that is the vehicle communication target through the terminal. The method of claim 21,
The side link radio bearing configuration information,
A base station including RLC bearer configuration information including information for bidirectional AM RLC configuration. The method of claim 21,
The side link failure information,
A base station comprising destination L2 ID information.

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