KR20210018049A - Method of connection control for direct communication between terminals, and apparatus therefor - Google Patents

Abstract

A connection configuration method for direct communication between terminals performed by a terminal comprises: a step of transmitting a sensing signal or a sidelink discovery signal; a step of transmitting sidelink discovery information; a step of receiving a response to the sidelink discovery information or the sidelink discovery signal from an opposite terminal; a step of determining a cast type for an opposite terminal, and configuring PC5-RRC connection with the opposite terminal if the cast type is determined to be a unicast scheme or a group cast scheme; and a step of performing direct communication between the opposite terminal and the terminal.

Description

Connection control method for direct communication between terminals, and apparatus therefor {Method of connection control for direct communication between terminals, and apparatus therefor}

The present invention relates to direct communication between terminals in a high frequency band-based mobile communication system, and more particularly, efficient radio resource allocation and connection control that satisfies user and service performance requirements required in a radio link for direct communication between terminals. It relates to a method and an apparatus for the same.

In order to cope with the rapidly increasing increase in wireless data, mobile communication systems are considering a terminal device that supports a transmission frequency of 6GHz to 90GHz for a wide system bandwidth. In addition, a method for providing a service by establishing a direct radio link between terminals in addition to a method of establishing a connection on a radio link with a base station (or cell), a node to which function separation is applied, or a relay node to receive service is considered. have.

In this way, radio resource allocation for connection establishment/management for wireless section for direct communication between terminals for connected cars as well as general user terminals based on mobile communication systems, connection control, efficient radio link monitoring, and Operation and control procedures in the radio protocol to support the measurement function are required.

An object of the present invention for solving the above problems is to provide a connection control method for direct communication between terminals.

Another object of the present invention for solving the above problems is to provide a configuration of a terminal that performs a connection control method for direct communication between terminals.

An embodiment of the present invention for achieving the above object is a connection establishment method for direct communication between terminals performed in a terminal, comprising: transmitting a sensing signal or a sidelink discovery signal; Transmitting sidelink discovery information; Receiving a response to the sidelink discovery signal or the sidelink discovery information from a counterpart terminal; When the cast type of the counterpart terminal is determined, and the cast type is determined by the unicast method or the groupcast method, a PC5-RRC (radio resource control) connection with the counterpart terminal is established. Setting up; And performing direct communication between the counterpart terminal and the terminal.

The connection setting method includes establishing an RRC connection with a base station; And receiving a radio resource allocated from the base station, and the sensing signal or the sidelink discovery signal may be transmitted through the radio resource.

The connection setting method further includes the step of checking a preset radio resource pool or receiving setting information of a radio resource pool from a base station, and the sensing signal or a sidelink discovery signal is selected from the radio resource pool. It can be transmitted through radio resources.

The sensing signal may be a signal for radio link monitoring (RLM, radio link monitoring), radio resource management (RRM), radio link failure (RLF) detection, or beam management. .

The sidelink discovery signal may be a reference signal having a specific pattern or a signal composed of a specific sequence.

The sidelink discovery signal is transmitted in a preset subcarrier area according to a preset period, and the preset period and/or a preset subcarrier area is received from the base station using system information or a control message. Can be.

The discovery information may include an L1 (layer 1) or L2 (layer 2) identifier (ID, identifier) of a source terminal, an L1 or L2 identifier of a target terminal, and/or an L1 or L2 identifier of a target terminal group.

The cast type is identified by the L1 or L2 ID of the source terminal, the L1 or L2 ID of the target terminal, and/or the L1 or L2 ID of the target terminal group, or SCI transmitted to the counterpart terminal or received from the counterpart terminal ( sidelink control information) or an indicator included in the SCI, or based on a HARQ retransmission method for the counterpart terminal or radio resource allocation information for transmitting HARQ feedback information for the counterpart terminal.

The step of establishing the PC5-RRC connection with the counterpart terminal includes: transmitting a control message requesting PC5-RRC connection establishment to the counterpart terminal; And it may include the step of receiving a response message for accepting or rejecting the PC5-RRC connection establishment from the counterpart terminal.

The control message requesting the PC5-RRC connection establishment includes the capability information of the terminal, the identifier and configuration information of the terminal, sidelink channel configuration information, version information of the direct communication function standard, and movement status. It may include at least one of (mobility status) information.

Another embodiment of the present invention for achieving the above object is a method for establishing a connection for direct communication between terminals performed in a terminal, comprising: monitoring a sensing signal or a sidelink discovery signal; Receiving sidelink discovery information from an opposite terminal; Transmitting the sidelink discovery signal or a response to the sidelink discovery information; Establishing a PC5-RRC connection with the counterpart terminal; And performing direct communication between the counterpart terminal and the terminal.

The terminal may recognize the counterpart terminal through monitoring of the sensing signal or the discovery signal, and may receive the sidelink discovery information from the counterpart terminal.

The sensing signal may be a signal for radio link monitoring (RLM, radio link monitoring), radio resource management (RRM), radio link failure (RLF) detection, or beam management. .

The sidelink discovery signal may be a reference signal having a specific pattern or a signal composed of a specific sequence.

The sidelink discovery signal is received in a preset subcarrier area according to a preset period, and the preset period and/or a preset subcarrier area is received from the base station using system information or a control message. Can be.

The discovery information may include an L1 (layer 1) or L2 (layer 2) identifier (ID, identifier) of a source terminal, an L1 or L2 identifier of a target terminal, and/or an L1 or L2 identifier of a target terminal group.

An embodiment of the present invention for achieving the above other object is a terminal for performing direct communication between terminals, comprising: a processor; A memory in electronic communication with the processor; And instructions executed by the processor and stored in the memory. When the commands are executed by the processor, transmitting, by the terminal, a sensing signal or a sidelink discovery signal; Transmitting sidelink discovery information; Receiving a response to the sidelink discovery signal or the sidelink discovery information from a counterpart terminal; When the cast type of the counterpart terminal is determined, and the cast type is determined by the unicast method or the groupcast method, a PC5-RRC (radio resource control) connection with the counterpart terminal is established. Setting up; And performing direct communication between the counterpart terminal and the terminal.

The sidelink discovery signal may be a reference signal having a specific pattern or a signal composed of a specific sequence.

The sidelink discovery signal is transmitted in a preset subcarrier area according to a preset period, and the preset period and/or a preset subcarrier area is received from the base station using system information or a control message. Can be.

The cast type is identified by the L1 or L2 ID of the source terminal, the L1 or L2 ID of the target terminal, and/or the L1 or L2 ID of the target terminal group, or SCI transmitted to the counterpart terminal or received from the counterpart terminal ( sidelink control information) or an indicator included in the SCI, or based on a HARQ retransmission method for the counterpart terminal or radio resource allocation information for transmitting HARQ feedback information for the counterpart terminal.

According to embodiments of the present invention, radio resource allocation, connection control, radio link monitoring, and measurement functions for connection establishment/management for a radio section for direct communication between terminals can be efficiently performed.

1 is a conceptual diagram illustrating an embodiment of a wireless communication network.
2 is a block diagram showing an embodiment of a communication node constituting a wireless communication network.
3 is a state transition diagram illustrating an example of state management of a terminal applied to embodiments of the present invention.
4 is a conceptual diagram illustrating scenarios of direct communication between terminals based on a mobile communication network.
5 is a conceptual diagram illustrating network interfaces of a vehicle communication system based on a mobile communication network.
6A and 6B are conceptual diagrams for explaining an example of a radio protocol configuration of a terminal for direct communication using a sidelink radio channel.
7 is a flowchart illustrating an embodiment of a method for establishing a connection between terminals for direct communication according to the present invention.

In the present invention, various modifications may be made and various embodiments may be provided, and specific embodiments will be illustrated in the drawings and described in detail in the detailed description. However, this is not intended to limit the present invention to a specific embodiment, it is to be understood to include all changes, equivalents, and substitutes included in the spirit and scope of the present invention. In describing each drawing, similar reference numerals have been used for similar elements.

Terms such as first, second, A, and B may be used to describe various elements, but the elements should not be limited by the terms. These terms are used only for the purpose of distinguishing one component from another component. For example, without departing from the scope of the present invention, a first element may be referred to as a second element, and similarly, a second element may be referred to as a first element. The term and/or includes a combination of a plurality of related listed items or any of a plurality of related listed items.

When a component is referred to as being "connected" or "connected" to another component, it is understood that it may be directly connected or connected to the other component, but other components may exist in the middle. Should be. On the other hand, when a component is referred to as being "directly connected" or "directly connected" to another component, it should be understood that there is no other component in the middle.

The terms used in the present application are only used to describe specific embodiments, and are not intended to limit the present invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In the present application, terms such as "comprise" or "have" are intended to designate the presence of features, numbers, steps, actions, components, parts, or combinations thereof described in the specification, but one or more other features. It is to be understood that the presence or addition of elements or numbers, steps, actions, components, parts, or combinations thereof, does not preclude in advance.

Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which the present invention belongs. Terms as defined in a commonly used dictionary should be interpreted as having a meaning consistent with the meaning in the context of the related technology, and should not be interpreted as an ideal or excessively formal meaning unless explicitly defined in this application. Does not.

Hereinafter, preferred embodiments of the present invention will be described in more detail with reference to the accompanying drawings. In describing the present invention, in order to facilitate an overall understanding, the same reference numerals are used for the same elements in the drawings, and duplicate descriptions for the same elements are omitted.

A communication system to which embodiments according to the present invention are applied will be described. The communication system may be a 4G communication system (eg, a long-term evolution (LTE) communication system, an LTE-A communication system), a 5G communication system (eg, a new radio (NR) communication system), or the like. A 4G communication system can support communication in a frequency band of 6 GHz or less, and a 5G communication system can support communication in a frequency band of 6 GHz or more as well as a frequency band of 6 GHz or less. The communication system to which the embodiments according to the present invention are applied is not limited to the contents described below, and the embodiments according to the present invention can be applied to various communication systems. Here, the communication system may be used with the same meaning as a communication network, and “LTE” may indicate “4G communication system”, “LTE communication system” or “LTE-A communication system”, and “NR” May designate “5G communication system” or “NR communication system”.

A wireless communication network to which embodiments according to the present invention are applied will be described. The wireless communication network to which the embodiments according to the present invention are applied is not limited to the contents described below, and the embodiments according to the present invention can be applied to various wireless communication networks. Here, the wireless communication network may have the same meaning as a wireless communication system.

1 is a conceptual diagram illustrating an embodiment of a wireless communication network.

Referring to FIG. 1, a wireless communication network 100 includes a plurality of communication nodes 110-1, 110-2, 110-3, 120-1, 120-2, 130-1, 130-2, and 130-3. , 130-4, 130-5, 130-6). Each of the plurality of communication nodes may support at least one communication protocol. For example, each of the plurality of communication nodes is a communication protocol based on code division multiple access (CDMA), a communication protocol based on wideband CDMA (WCDMA), a communication protocol based on time division multiple access (TDMA), and frequency division multiple access (FDMA). access) based communication protocol, OFDM (orthogonal frequency division multiplexing) based communication protocol, OFDMA (orthogonal frequency division multiple access) based communication protocol, SC (single carrier)-FDMA based communication protocol, NOMA (Non-orthogonal Multiple) Access), SDMA (Space Division Multiple Access) based communication protocol, etc. can be supported. Each of the plurality of communication nodes may have the following structure.

2 is a block diagram showing an embodiment of a communication node constituting a wireless communication network.

Referring to FIG. 2, the communication node 200 may include at least one processor 210, a memory 220, and a transmission/reception device 230 connected to a network to perform communication. In addition, the communication node 200 may further include an input interface device 240, an output interface device 250, and a storage device 260. Each of the components included in the communication node 200 may be connected by a bus 270 to perform communication with each other.

The processor 210 may execute a program command stored in at least one of the memory 220 and the storage device 260. The processor 210 may mean a central processing unit (CPU), a graphics processing unit (GPU), or a dedicated processor on which methods according to embodiments of the present invention are performed. Each of the memory 220 and the storage device 260 may be configured with at least one of a volatile storage medium and a nonvolatile storage medium. For example, the memory 220 may be formed of at least one of a read only memory (ROM) and a random access memory (RAM).

Referring back to FIG. 1, the wireless communication network 100 includes a plurality of base stations 110-1, 110-2, 110-3, 120-1, 120-2, and a plurality of UEs (users). equipment) (130-1, 130-2, 130-3, 130-4, 130-5, 130-6). Each of the first base station 110-1, the second base station 110-2, and the third base station 110-3 may form a macro cell. Each of the fourth base station 120-1 and the fifth base station 120-2 may form a small cell. The fourth base station 120-1, the third UE 130-3 and the fourth UE 130-4 may belong to the cell coverage of the first base station 110-1. The second UE 130-2, the fourth UE 130-4, and the fifth UE 130-5 may belong to the cell coverage of the second base station 110-2. The fifth base station 120-2, the fourth UE 130-4, the fifth UE 130-5, and the sixth UE 130-6 may belong within the cell coverage of the third base station 110-3. have. The first UE 130-1 may belong to the cell coverage of the fourth base station 120-1. The sixth UE 130-6 may belong to the cell coverage of the fifth base station 120-2.

Here, each of the plurality of base stations 110-1, 110-2, 110-3, 120-1, and 120-2 is a NodeB, an evolved NodeB, a base transceiver station (BTS), It may be referred to as a radio base station, a radio transceiver, an access point, an access node, and the like. Each of the plurality of UEs 130-1, 130-2, 130-3, 130-4, 130-5, and 130-6 is a terminal, an access terminal, a mobile terminal, Station (station), subscriber station (subscriber station), mobile station (mobile station), portable subscriber station (portable subscriber station), node (node), may be referred to as a device (device).

A plurality of communication nodes (110-1, 110-2, 110-3, 120-1, 120-2, 130-1, 130-2, 130-3, 130-4, 130-5, 130-6) Each is cellular communication (e.g., long term evolution (LTE), LTE-A (advanced), etc. as specified in the 3GPP (3rd generation partnership project) standard), or mmWave (e.g., 6GHz~80GHz band ) Can support the wireless protocol standard of the wireless access technology. Each of the plurality of base stations 110-1, 110-2, 110-3, 120-1, and 120-2 may operate in a different frequency band or may operate in the same frequency band. Each of the plurality of base stations 110-1, 110-2, 110-3, 120-1, and 120-2 may be connected to each other through an ideal backhaul or a non-ideal backhaul, and the ideal backhaul Alternatively, information can be exchanged with each other through non-ideal backhaul. Each of the plurality of base stations 110-1, 110-2, 110-3, 120-1, and 120-2 may be connected to a core network (not shown) through an ideal backhaul or a non-ideal backhaul. Each of the plurality of base stations 110-1, 110-2, 110-3, 120-1, and 120-2 transmits a signal received from the core network to the corresponding UEs 130-1, 130-2, 130-3, 130 -4, 130-5, 130-6), and a signal received from the corresponding UE (130-1, 130-2, 130-3, 130-4, 130-5, 130-6) Can be transferred to.

In addition, each of the plurality of base stations 110-1, 110-2, 110-3, 120-1, and 120-2 transmits multiple input multiple output (MIMO) (eg, single user (SU)-MIMO, Multi-user (MU)-MIMO, massive MIMO, etc.), coordinated multipoint (CoMP) transmission, carrier aggregation (CA) transmission, transmission in an unlicensed band, direct communication between terminals (device to device communication, D2D) ) (Or, ProSe (proximity services), etc. may be supported. Here, each of the plurality of UEs 130-1, 130-2, 130-3, 130-4, 130-5, and 130-6 is a base station ( Operation corresponding to 110-1, 110-2, 110-3, 120-1, 120-2), supported by base stations (110-1, 110-2, 110-3, 120-1, 120-2) For example, the second base station 110-2 may transmit a signal to the fourth UE 130-4 based on the SU-MIMO scheme, and the fourth UE 130-4 ) May receive a signal from the second base station 110-2 by the SU-MIMO scheme, or the second base station 110-2 transmits a signal based on the MU-MIMO scheme to the fourth UE 130- 4) and the fifth UE (130-5), each of the fourth UE (130-4) and the fifth UE (130-5) from the second base station (110-2) by the MU-MIMO method Each of the first base station 110-1, the second base station 110-2, and the third base station 110-3 transmits signals to the fourth UE 130-4 based on the CoMP scheme. And the fourth UE 130-4 can receive signals from the first base station 110-1, the second base station 110-2, and the third base station 110-3 by the CoMP method. Yes, a plurality of base stations 110-1 and 11 0-2, 110-3, 120-1, 120-2) Each UE (130-1, 130-2, 130-3, 130-4, 130-5, 130-6) belonging to its own cell coverage It can transmit and receive signals based on the and CA method. Each of the first base station 110-1, the second base station 110-2, and the third base station 110-3 coordinates D2D between the fourth UE 130-4 and the fifth UE 130-5 ( coordination), and each of the fourth UE 130-4 and the fifth UE 130-5 is D2D or V2X by coordination of the second base station 110-2 and the third base station 110-3. Service can be performed.

Next, methods of operation of a communication node in a wireless communication network will be described. Even when a method performed in the first communication node (for example, transmission or reception of a signal) among communication nodes is described, the second communication node corresponding thereto is a method corresponding to the method performed in the first communication node (e.g. For example, signal reception or transmission) may be performed. That is, when the operation of the UE is described, the corresponding base station may perform the operation corresponding to the operation of the UE. Conversely, when the operation of the base station is described, the UE corresponding thereto may perform an operation corresponding to the operation of the base station.

In the following description, the SGW is an end node of a core network for exchanging data packets with a base station that provides a service to a user terminal using a radio access protocol. In addition, the MME is an entity in charge of a control function in a wireless access section (or interface) for user terminals in a wireless communication network. Therefore, in the following description, the present invention is not limited to the specific terms'SGW' or'MME'. That is, the terms may be replaced with a function supporting a radio access protocol according to a radio access technology (RAT) or another term referring to a subject performing a corresponding function according to the configuration of a core network.

When the dual connectivity function is supported, the terminal may establish a connection with a plurality of base stations and receive services from a plurality of connected base stations. According to the role of the base stations supporting the dual connectivity function to the terminal, it may be classified into a master base station and a secondary base station. Hereinafter,'dual connectivity' refers to dual connectivity using multiple base stations using the same radio access technology (RAT) and dual connectivity using multiple base stations using different radio access standards (MR-DC: Multi-Radio Dual Connectivity) may be included.

Here, the master base station (or node) refers to a node that proactively performs a Radio Resource Control (RRC) function to support a dual connectivity function and supports a control plane connection function with a core network. The master node may be composed of a plurality of cells, and a plurality of cells constituting the master node may be referred to as a master cell group (MCG). The MCG bearer refers to a bearer that follows only the RLC of a cell belonging to the MCG and a logical channel configuration of the MAC layer.

In addition, the secondary base station (or node) refers to a node that does not support a control plane connection function with a core network, but provides a service by using additional radio resources to a terminal device to support a dual connection function. The secondary node may be composed of a plurality of cells, and a plurality of cells constituting the secondary node may be referred to as a SCG (Secondary Cell Group). The SCG bearer means a bearer according to only the logical channel configuration of the MAC layer and the RLC of a cell belonging to the SCG.

On the other hand, the split bearer is a bearer using the MAC and RLC layer logical channel configuration of the MCG and SCG together. This split bearer may be classified as an SN terminated bearer or an MN terminated bearer according to the type of a node performing the PDCP function. The MN end bearer is a bearer in which the PDCP function for the corresponding bearer is performed in the master node, and the SN end bearer is the bearer in which the PDCP function for the corresponding bearer is performed in the secondary node.

3 is a state transition diagram illustrating an example of state management of a terminal applied to embodiments of the present invention.

The terminal can operate in a connected state 301, an inactive state 302, or an idle state 303 according to the connection establishment state with the base station providing the service. . The terminal in the connection state 301 and the inactive state 302 stores and manages RRC context information together with the base station (310). When the terminal transitions to the idle state 303 through the procedure 305 or 309, the RRC context information is deleted. Here, the RRC context information includes an identifier assigned to the corresponding terminal, and additionally, parameters set for protocol data unit (PDU) session information, security key, capability information, etc. Can include.

The terminal in the idle state 303 monitors the downlink signal or performs a measurement operation in the on-duration period or active time according to the DRX (Discontinuous Reception) period set for the low power consumption operation. , A cell selection or reselection operation for camping to an optimal base station (or cell) may be performed. The terminal may acquire system information to camp in a new cell. The terminal can request required system information if necessary. In addition, the UE may perform an operation for receiving a downlink paging message in on-duration or active time according to a set paging occasion.

The terminal in the connection state 301 establishes a serving cell (or base station) and a radio bearer (e.g., a data bearer (DRB) or a signaling bearer (SRB)) to connect RRC context information required in the state can be stored and managed. The terminal in the connected state monitors the physical layer downlink control channel (PDCCH) using the stored and managed RRC context information and the connection configuration information from the base station, and receives the downlink packet scheduled and transmitted by the serving cell or uplink. A packet can be transmitted to a serving cell using uplink grant information. The mobility function for the terminal in the connected state 301 is performed through a handover procedure when the cell is changed. For such a handover procedure, the UE may perform a measurement operation on a serving cell or an adjacent cell according to a measurement or reporting parameter set by the serving cell, and report the result to the serving cell. In addition, the terminal in the connected state 301 may perform the DRX operation according to the DRX operation configuration parameter in the connected state set by the serving cell. The terminal in the connection state 301 performing the DRX operation may perform the PDCCH monitoring operation in an on-duration period or active time according to the DRX period.

The terminal in the inactive state 302 may store and manage RRC context information required in the inactive state. The UE in the inactive state 302 or the idle state 303 may perform a DRX operation according to the DRX parameter set by the last serving cell. According to the DRX period, the UE may monitor or measure a downlink signal during an on-duration period or an active time, and thus perform a cell selection or reselection operation for camping to an optimal base station (or cell). The terminal may acquire system information to camp in a new cell. The terminal can request required system information if necessary. In addition, the UE in the inactive state or the dormant state may perform an operation for receiving a downlink paging message in an on-duration period or an active time according to a set paging occasion.

A beamforming technique may be applied for transmission and reception on a radio link between a base station (or cell) and a terminal. A signal transmitted by the terminal may be used to provide a mobility function between base stations or to select an optimal beam within the base station. The terminal may be provided with a service by establishing a connection with one or more cells (or base stations). Alternatively, the terminal may exist in the service area of the corresponding base station in a state in which only connection configuration is maintained (eg, in a state in which AS context information is stored and managed) or in a state in which there is no connection configuration.

In a mobile communication system using a base station to which a beamforming technique is applied in a high frequency band, a beam level mobility support function that changes the configuration beam of a terminal within the base station and a configuration beam or radio link between base stations (or cells) Mobility support and radio resource management functions to change the data may be considered.

In order to support mobility and perform radio resource management functions, the base station transmits a synchronization signal or a reference signal so that the terminal can search or monitor. In the case of a base station using a frame format supporting a plurality of symbol lengths to support multi-numerology, monitoring by the terminal is performed by initial numerology or default numerology. ) Or a synchronization signal or a reference signal configured (or set) with a default symbol length.

Here, the initial neurology or default neurology is a frame format applied to radio resources in which a UE-common search space is set, and the physical layer of the 3GPP NR (New Radio Access Technology) system is downlinked. A frame format applied to a radio resource for which a control resource set (CORESET (CORESET)) ZERO (or CORESET #0) of the link control channel is set, or a synchronization symbol that can identify a cell in a 3GPP NR system It may be a configuration of a frame format applied to radio resources in which a synchronization symbol burst is transmitted.

Here, the frame format is a subcarrier spacing (subcarrier spacing (SCS)) constituting a radio frame (or subframe), a configuration of a control channel (e.g., a configuration of CORESET), a configuration of a symbol (or slot), or Information on setting parameters such as a reference signal configuration (e.g., a value of the setting parameter, an offset, an index, an identifier, a range, a period, or an interval (interval or duration)) It can mean. Information on the frame format may be delivered to the terminal using system information or a dedicated control message.

In addition, the terminal that has established a connection with the base station monitors the set beam or the activated beam through transmission of an uplink dedicated reference signal set by the base station or reception of a downlink dedicated reference signal set by the base station. Through beam management operation can be performed.

For example, the base station generates a synchronization signal (SS: Synchronization Signal) and/or a downlink reference signal so that the UE in the service area can search for itself and perform downlink synchronization, beam setting, or radiolink monitoring operation. send. In addition, the terminal establishing a connection with the serving base station receives radio resource configuration information of the physical layer for connection establishment and radio resource management from the serving base station.

Here, the radio resource configuration information of the physical layer is PhysicalConfigDedicated, PhysicalCellGroupConfig, PDCCH-Config, PDCCH-PDCCH-ConfigSIB1, ConfigCommon, PUCCH-Config, RACH-ConfigCommon, RACH-ConfigDedicated, RadioResourceConfigCommon, RadioResourceConfigDedicated, or ServingCellConfig of the LTE or NR system. Refers to configuration parameters in an RRC control message such as ServingCellConfigCommon, and may include the following information. The configuration information includes the setting (or allocation) period of the corresponding signal (or radio resource) based on the frame format of the base station (or transmission frequency), and the time domain/frequency domain of the radio resource for transmission. ), or parameter values such as transmission (or allocation) timing. Here, the frame format of the base station (or transmission frequency) has a plurality of symbol lengths according to a plurality of subcarrier spacings (SCS) in one radio frame in order to support multi numerology. It means the frame format. That is, the number of symbols constituting mini-slots, slots, and subframes existing in one radio frame (eg, a frame of 10 ms) may be different.

(1) Base station transmission frequency and frame format setting information

-Transmission frequency information: information on all transmission carriers (i.e., transmission frequency per cell) in the base station, information on BWPs, information on a transmission time reference or time difference between transmission frequencies in the base station (for example, , Transmission period or offset parameter indicating the transmission reference time (or time difference) of the synchronization signal), etc.

-Frame format information: setting parameters of mini-slots, slots, and subframes supporting multiple symbol lengths according to subcarrier spacing

(2) Downlink reference signal (e.g., CSI-RS (Channel State Information-Reference Signal), common reference signal (Common-RS), etc.) configuration information

-Setting parameters such as transmission period, transmission location, code sequence, or masking (or scramble) sequence for a reference signal commonly applied in the coverage of a base station (or beam)

(3) Uplink control signal setting information

-SRS (Sounding Reference Signal), uplink beam sweeping (or beam monitoring) reference signal (RS), or uplink grant-free radio resource, or uplink radio resource for random access (or RA Setting parameters such as preamble)

(4) Physical downlink control channel (PDCCH) configuration information

-A reference signal (RS) for PDCCH demodulation, a beam common reference signal (e.g., a reference signal that can be received by all terminals within the beam coverage), a beam sweeping (or beam monitoring) reference signal, or a reference signal for channel estimation. Setting parameters

(5) Physical layer uplink control channel (PUCCH: Physical Uplink Control Channel) configuration information

(6) Scheduling Request signal setting information

(7) Setting information on feedback (ACK or NACK) transmission resources for HARQ function support

(8) Number of antenna ports, information on antenna array, beam configuration or beam index mapping information for applying a beamforming technique

(9) Downlink and/or uplink signal (or uplink access channel resource) configuration information for beam sweeping (or beam monitoring)

(10) Beam that triggers beam configuration, beam recovery, beam reconfiguration, or radio link re-establishment operation, beam change operation within the same base station, or handover to another base station Parameter setting information such as the received signal and the operation control timer

In the case of a radio frame format supporting a plurality of symbol lengths to support multi numerology, a period of setting (or allocation) of a parameter constituting the information, position information on the time axis/frequency axis of the radio resource, Alternatively, the transmission (or allocation) timing, etc. may be information set for each corresponding symbol length (or subcarrier interval).

In the following description,'Resource-Config information' may mean a control message for configuring radio resources including at least one parameter among radio resource configuration information of the physical layer. In the following description, a property or setting value (or range) of an information element (or parameter) delivered by a corresponding control message may have meaning rather than the name'Resource-Config information'. Therefore, the information element (or parameter) transmitted by the Resource-Config control message is applied as common to the entire coverage of the base station (or beam), or dedicated to a specific terminal device (or terminal device group). It may be radio resource setting information. The configuration information of the Resource-Config information described above may be configured as one control message or different control messages according to configuration information properties. In addition, the beam index is an index (or identifier) of a reference signal mapped or associated with a corresponding beam, or a TCI state (Transmission Configuration Indicator state) for beam management, regardless of the index of the transmission beam or the index of the reception beam. ) Can be used.

Accordingly, a terminal device in a connected state receives a service using a serving cell (or a base station) and a set beam. The terminal device is a downlink synchronization signal of a serving cell (e.g., SSB (SS/PBCH block: Synchronization Signal/Physical Broadcast Channel) of a 3GPP NR system) or a downlink reference signal of a serving cell (e.g., A downlink radio channel is searched for or monitored using CSI-RS (CSI Reference Signal-Reference Signal). Here, the fact that the beams are configured (or beam paired) to receive a service means that a packet is transmitted or received through an activated beam among one or more configured beams. In the 3GPP NR system, the beam is activated means that the configured TCI state is activated.

In addition, when the terminal is in an idle state or in an inactive state, a downlink radio channel is searched for or monitored using a parameter obtained or set from system information or common Resource-Config information. In addition, the terminal may attempt access or transmit control information using an uplink channel (eg, random access or a physical layer uplink control channel).

Through such a radio link monitoring (RLM) operation, the terminal may detect a radio link problem. Here, when a radio link problem is detected, it means that there is an error in setting or maintaining the synchronization of the physical layer for the radio link. That is, it means that it is detected that the physical layer synchronization of the terminal is not maintained for a certain period of time. When a radio link problem is detected, a radio link recovery operation is performed. When a radio link failure is not performed, a radio link failure (RLF) is declared and a radio link re-establishment procedure is performed.

Physical layer problem detection, radio link recovery, radio link failure detection (or declaration), radio link re-establishment according to such radio link monitoring operation In procedures such as, Layer 2 of a radio protocol constituting a radio link (Layer 1 or Physical layer), Medium Access Control (MAC), Radio Link Control (RLC), Packet Data Convergence Protocol (PDCP), etc. Functions of, or Layer 3 functions such as Radio Resource Control (RRC) may participate.

The physical layer of the terminal may receive a downlink synchronization signal and/or a reference signal (RS) to monitor the radio link. In this case, the reference signal may be a base station common reference signal (Common RS), a beam common reference signal, or a dedicated reference signal allocated to a terminal (or terminal group). Here, the common reference signal means a reference signal that can be received by all terminals within the coverage (or service area) of a corresponding base station or beam to estimate a channel. In addition, the dedicated reference signal refers to a reference signal that can be received by only a specific terminal or terminal group within the coverage of a base station or a beam to estimate a channel.

Accordingly, when a base station or a set beam is changed, a dedicated reference signal for management of the changed beam may be changed. This means that a procedure for selecting a different beam from among beams set through a configuration parameter between the base station and the terminal or changing the set beam is required. In the 3GPP-based NR system, the change of the beam means that an index of another TCI state is selected from among the set TCI state indexes (or identifiers), or a new TCI state is set and the activated state is changed. The configuration information for the common reference signal can be obtained by the terminal through system information. Alternatively, in the case of a handover in which the base station is changed or connection reconfiguration, the base station may transmit the common reference signal configuration information to the terminal device through a dedicated control message.

Depending on the configuration condition of the radio protocol layer of the base station (or cell), information for identifying the corresponding transmitting base station may be transmitted to the terminal using an RRC layer, a MAC layer control message, or a physical layer control channel. Here, the information for distinguishing the transmitting base station (or transmitting node) is the identifier of the base station (or transmitting node), reference signal information, a configured beam (or configured TCI state). ) Information, or sequence (or scramble) identifier information for a base station (or a transmitting node).

The reference signal information may be radio resources of a reference signal allocated for each transmission base station, sequence information or index information of a reference signal, or sequence information or index information of a dedicated reference signal allocated to a terminal. Here, the radio resource of the reference signal may refer to a parameter indicating a position of a symbol on a time axis in which a reference signal is transmitted within a radio resource region such as a frame, a subframe, or a slot, and a position of a relative or absolute subcarrier on the frequency axis. . These parameters may be expressed as an index indicating a corresponding radio resource element or a radio resource set, a symbol or a number sequentially assigned to a subcarrier. Hereinafter, the reference signal information means the transmission period described above, the code sequence of the reference signal, or masking (or scramble), the radio resource of the reference signal, or index information. The reference signal identifier refers to a parameter (eg, resource ID, resource set ID) capable of uniquely distinguishing reference signal information from among one or more reference signal information.

The set beam information is the index (or identifier) of the set beam (or set TCI state), configuration information of the corresponding beam (eg, transmission power, beam width, angle on vertical/horizontal, etc.), transmission or reception timing of the corresponding beam (Eg, index or offset value of a subframe, slot, mini slot, symbol, etc.) information, reference signal information corresponding to a corresponding beam, or reference signal identifier information.

In addition, the base station may be installed in the air such as a drone, an aircraft, or a satellite to perform the operation of the base station described in the present invention.

Accordingly, the terminal performs a beam monitoring operation, radio access (or access) using the identification information of the transmitting base station (or transmitting node), which is transmitted by the base station using a control message of the RRC layer, the MAC layer, or a control channel of the physical layer. An operation or a target base station (or a transmitting node) to perform a transmission/reception operation of a control (or data) packet can be identified.

In addition, when multiple beams are configured for the terminal, the base station and the terminal may transmit and receive packet information through all configured beams, and the number of downlink beams and uplink beams may be mapped to the same or differently. For example, a plurality of downlink beams from the base station to the terminal may be configured and one uplink beam from the terminal to the base station may be configured.

The base station changes the beam properties (or TCI status properties) (primary beam, secondary beam, spare (or candidate) beam, active beam, or inactive beam, etc.) based on the UE's beam measurement or reporting the result of beam monitoring. I can. Here, when the TCI state is changed, the attribute of the TCI state may be changed to a primary TCI state, a secondary TCI state, a reserve (or candidate) TCI state, a configured TCI state, an active TCI state, or an inactive TCI state. I can.

As described above with respect to the attribute of the TCI state, the state in which data packets or control signaling, etc. can be transmitted or received even if limited, such as the primary TCI state or the secondary TCI state, is an active TCI state or a serving TCI state. Can be assumed. In addition, a state in which data packets or control signaling cannot be transmitted or received while being measured or managed, such as a preliminary (or candidate) TCI state, may be assumed to be a deactivate TCI state or a configured TCI state.

Change of the beam (or TCI state) attribute may be controlled in the RRC layer or the MAC layer. When the MAC layer changes the properties of the beam (or TCI state), the MAC layer notifies the upper layer of the change of the beam properties. In addition, the change of the beam attribute may be transmitted to the terminal using a control message of the MAC layer or a physical layer control channel (eg, a physical downlink control channel (PDCCH) of an LTE (or NR) system). Here, in the case of using the physical layer control channel, the control information may be configured in the form of downlink control information (DCI), uplink control information (UCI), or a separate indicator (or field information) of the LTE (or NR) system.

The terminal may request to change the TCI state attribute based on the beam measurement or beam monitoring result. Control information or feedback information for requesting to change the TCI state attribute by the UE may be transmitted using a physical layer control channel, a MAC layer control message, or an RRC control message. The control message, signaling information, or feedback information for changing the TCI state attribute may be configured using at least one parameter among the above-described configuration beam information.

The change in the properties of the beam (or TCI state) described above is changed from an active beam to an inactive beam or a spare (or candidate) beam, a primary beam to a secondary beam or a spare (or candidate) beam, or vice versa. It means to be changed. That is, it means that the properties of the beam are changed between the properties of the beams described above, and the beam properties can be changed in the RRC layer or the MAC layer. If necessary, the beam property change may be performed through partial cooperation between the RRC layer and the MAC layer.

In addition, when multiple beams are allocated, a beam for transmitting a physical layer control channel can be set and operated. That is, it may be configured to transmit a physical layer control channel using all of the plurality of beams (eg, primary beam or secondary beam) or to transmit the physical layer control channel only with the primary beam.

Here, the physical layer control channel is a channel such as PDCCH or PUCCH of an LTE (or NR) system, and scheduling information including radio resource element (RE) allocation and Modulation and Coding Scheme (MCS) information, Channel Quality Indication (CQI), PMI (Precoding Matrix Indicator), feedback information such as ACK/NACK of HARQ, resource request information such as SR (Scheduling Request), beam monitoring result (or TCI state ID) for supporting the beamforming function, or active or inactive beams Transmit measurement information, etc.

In the above description, radio resources are parameters on the frequency axis, such as center frequency, system bandwidth, and subcarrier, and radio frames, sub-frames, TTI (Transmission Time Interval), slots, and minislots. It can be configured as a parameter on a time axis according to a unit of transmission (or reception) time (or period, interval, window) such as (mini-slot) or symbol. In addition, the radio resource is a hopping pattern of radio resources, a beam forming (or beam forming) technique (e.g., beam configuration information, beam index), or a code sequence (or bit sequence, signal sequence) using multiple antennas. It may refer to a resource occupied for transmission in a radio section by applying a characteristic. In the case of such a radio resource, a physical channel (or a transport channel) according to the type (or attribute) of transmitted data or control message, uplink, downlink, or sidelink (or side channel), etc. channel)) may be different.

Such a beam (or TCI state) or a reference signal for radio link management is a synchronization signal such as a synchronization signal (SS), a synchronization signal block (SSB), a channel state information reference signal (CSI-RS), and a phase tracking signal (PT-RS). Reference Signal), Sounding Reference Signal (SRS), or Demodulation Reference Signal (DM-RS) reference signal. The reference parameter for the reception quality of the beam (or TCI state) or the reference signal for radio link management may be set as a parameter such as a measurement unit time, a measurement interval, a reference value indicating the degree of improvement change, or a reference value indicating the degree of deterioration change. have. Measurement unit time or measurement interval is an absolute time basis (ms, sec, etc.), TTI (Transmission Timing Interval), symbol, slot, (sub) frame, radio channel configuration such as scheduling period, or base station/terminal operation period It can be set as such. In addition, a reference value representing the degree of change in reception quality may be set as an absolute value (dBm) or a relative value (dB). In addition, the reception quality of the beam (or TCI state) or the reference signal for radio link management is RSRP (Reference Signal Received Power), RSRQ (Reference Signal Received Quality), RSSI (Received Signal Strength Indicator), SNR (Signal-to- Noise Ratio), Signal-to-Interference Ratio (SIR), etc.

Meanwhile, in a 3GPP NR system using a millimeter frequency band, flexibility in channel bandwidth operation for packet transmission is secured by applying the concept of a bandwidth part (BWP). The base station may set up to 4 BWPs having different bandwidths to the terminal. BWPs may be independently configured for each downlink and uplink. Each BWP may have a different bandwidth as well as subcarrier spacing (SCS).

For example, the UE in the connected state 301 described in FIG. 3 is a serving cell or a cell (eg, a neighbor cell) that is a measurement object based on an SS/PBCH block or a CSI-RS. The signal quality of a radio link section for a target cell or a candidate cell, etc. can be measured. Here, the signal quality may be expressed as RSRP, RSRQ, RSSI, SNR, SIR, or SINR, which is referred to as the above-described beam (or TCI state) or the reception performance of a reference signal for radio link management.

In addition, the terminal in the inactive state 302 or the dormant state 303 of FIG. 3 is a radio for a serving cell (or camping cell) or an adjacent cell according to the DRX period (or measurement period) set based on the SS/PBCH block. The signal quality (eg, RSRP, RSRQ, SINR, or RSSI (Received Signal Strength Indicator)) of the link period can be measured. The terminal may perform a cell selection/reselection operation based on the measurement result. For measurement of a serving cell (or camping cell), the UE transmits the transmission period of the SS/PBCH block acquired through the system information of the corresponding cell (e.g., ssb-PeriodicityServingCell information) or the radio resource in which the SS/PBCH block is transmitted. Setting information (eg, ssb-PositionsInBurst information) may be obtained. In addition, in order to measure adjacent cells, the terminal may obtain signal measurement time configuration (SMTC) window information through system information. RAN area through identifier information transmitted as system information while the UE in the inactive state 302 or the dormant state 303 performs a cell selection/reselection operation based on measurement of an SS/PBCH block Alternatively, when it is recognized that a tracking area or the like has been changed, a RAN area or a tracking area update procedure may be performed.

4 is a conceptual diagram illustrating scenarios of direct communication between terminals based on a mobile communication network.

In FIG. 4, coverage of a cell (or a base station (Node B), an access point, a transmission and reception point (TRP), etc.)) in supporting a direct communication function based on a mobile communication network The scenarios of direct communication related to) are shown.

Referring to FIG. 4, scenario A is a case where there is no mobile communication cell (or a base station, node, etc.) capable of providing services to terminals (UE1 and UE2) performing direct communication. This case is classified as'out-of-coverage', and resource allocation and control signaling for direct communication may be performed in a distributed control method.

Scenario C and Scenario D are cases in which terminals (UE1 and UE2) performing direct communication are located within the service area of any cell (or base station, AP, node, etc.) that can provide a service. Scenario C is a case where terminals (UE1 and UE2) performing direct communication are located in the service area of the same cell (or node) ('In coverage-single-cell'). Scenario D is a case in which terminals (UE1 and UE2) performing direct communication are located in service areas of different cells (or nodes) ('In coverage-multi-cell').

Scenario B is a case in which UE1 is located in a service area of a mobile communication cell and UE2 is located outside a service area of a mobile communication cell among terminals performing direct communication. Such a case can be classified as'partial coverage'.

In the allocation of radio resources for sidelink (SL) (or PC5 interface) between terminals for direct communication, a base station control method or a distributed control (or terminal device determination) method according to the setting (or operation) of the mobile communication network Can be applied.

The base station control method (or mode 1) is a method in which the base station allocates resources through scheduling. That is, a terminal performing direct communication based on mode 1 may transmit control information/data for direct communication using a sidelink radio resource allocated by the base station. That is, as the base station allocates resources from the available direct communication resource pool, control information/data can be transmitted without collision between terminals performing direct communication.

On the other hand, in the distributed control (or terminal determination) method (or Mode2), the terminal performing direct communication from the radio resource pool for direct communication set by the system (or any base station (or cell)) independently This is a method of selecting and transmitting a transmission resource. Accordingly, a terminal performing direct communication based on mode 2 may transmit control information/data using a radio resource randomly selected from a radio resource pool for direct communication. Accordingly, a collision may occur between sidelink radio resources used by terminals performing direct communication.

5 is a conceptual diagram illustrating network interfaces of a vehicle communication system based on a mobile communication network.

The base stations NB-1 and NB-2 transmit packet messages for a control plane for transmitting/receiving control information or a user-plane for transmitting/receiving traffic data. Function) or UPF (User Plane Function) and NG interface.

In addition, a Road Side Unit (RSU) for a vehicle communication system may operate as a base station (or L2/L3 relay node) or as a terminal. An RSU (e.g., RSU1 in FIG. 5) operating as a base station (or an L2/L3 relay node) can exchange packet information with the base station through an Xn interface (however, if the RSU is a relay node, an Un interface). In addition, packet information can be exchanged with AMF (or UPF) through the NG interface. The NG interface is a logical interface and may be physically connected to the AMF (or UPF) via a base station.

Meanwhile, the RSU operating as a terminal (eg, RSU2 in FIG. 5) may exchange packet information through a base station and a Uu interface (however, if the RSU is a relay node, an Un interface).

In addition, a radio section between RSUs (eg, RSU1 and RSU2) may exchange packet information using a PC5 interface for direct communication or a Uu interface between the base station and the terminal.

In addition, packet information may be exchanged between the user terminals UE1 and UE2 and the vehicle terminals VT1 and VT2 through a PC5 interface for direct communication (ie, a radio resource or a radio channel of a sidelink). In particular, the PC5 interface for direct communication between user terminals (UE1, UE2) and vehicle terminals (VT1, VT2) is D2D (or V2X) communication for the existing user terminal equipment (UE) of the 3GPP LTE/LTE-A system. It may be a PC5 interface for, or a radio resource (or radio channel) of a sidelink or a radio interface for direct communication newly defined or changed in the 3GPP NR system.

Vehicle terminal (VT12 or VT2) exchanges packet information with RSU (or RSU in the form of L3/L2 (layer3/layer2) relay) through Uu interface (communication between VT1 and RSU1 in FIG. 5), base station (or L3/ L2 relay type node) and packet information can be exchanged (communication between VT2 and NB-22 in FIG. 5). In the above,'packet information exchange' may refer to a process of transmitting or receiving control signaling or traffic data packets with each other.

Both the mode 1 and mode 2 schemes described above can be applied to resource allocation for direct communication between terminals. The end node of the system (eg, cell, eNB, base station, AP, RSU, etc.) may transmit configuration information of the direct communication pool for mode 1 and mode 2 to the terminal through system information or a dedicated control message.

Direct communication between terminals using a sidelink radio channel may be performed in a broadcast method, a groupcast method, and a unicast method. In the broadcast method, a transmitting terminal transmits a sidelink radio channel to all nearby terminals capable of receiving. The groupcast scheme is a scheme in which only terminals belonging to a specific group can receive the radio channel of the sidelink transmitted by the transmitting terminal. In addition, in the unicast method, a terminal supporting a direct communication function establishes a one-to-one connection with a specific terminal using a sidelink radio channel, and transmits or receives information to or from the terminal.

Wireless protocol configuration for direct communication

6A and 6B are conceptual diagrams illustrating a configuration example of a radio protocol of a terminal for direct communication using a sidelink radio channel.

6A, a control plane for transmitting control information is a radio resource control (RRC) layer, a packet data convergence protocol (PDCP) layer, a radio link control (RLC) layer, and a medium access control (MAC) layer. , And PHY (physical) layer. Referring to FIG. 6B, a user plane for transmitting traffic data may include a service data adaptation protocol (SDAP) layer, a PDCP layer, an RLC layer, a MAC layer, and a PHY layer.

When the MAC layer transmits the MAC PDU (or SDU) to the physical layer, or the physical layer transmits a transport block (TB) (or coding block) to the counterpart terminal, the corresponding MAC PDU or transport block Transmission type (i.e., broadcast, groupcast, or unicast) of the transmission type can be identified, information about the transmission type is transmitted between layers together with the corresponding MAC PDU or transmission block (or encoding Block) may be transmitted to a peer UE. As a method for identifying the cast type, a method of using an identifier (ID), a method of using a sidelink control information (SCI) format, a method of including an indicator indicating a cast type in SCI, and the like may be considered.

The method of identifying a cast type using an identifier (ID) is a method in which the terminal recognizes the cast type based on a source identifier (source identifier), a destination identifier (destination identifier), or a destination group identifier (destination group identifier). . The source ID is the ID of the source terminal (i.e., the terminal transmitting data), the destination ID is the ID of the destination terminal (i.e., the terminal receiving data), and the destination group ID is the group to which the destination terminals belong It can mean the ID of. In this case, the source ID, the destination ID, or the destination group ID may be L2 ID (Layer 2 ID) or L1 (or PHY) ID. For example, the source L1 ID may be composed of a part of the source L2 ID. Alternatively, a source L1 ID and a source L2 ID may be configured as part of the ID of the terminal. That is, the source L1 ID is configured by using some low-order bits (eg, least significant bits (LSBs)) of the source L2 ID, or by using some low-order bits (LSBs) configuring the ID of the terminal. The source L1 ID may be configured, or the source L1 ID may be configured by a combination of the source L2 ID and some lower bits (LSBs) of the IDs of the terminal. The target L1 ID, the target L2 ID, the target group L1 ID, and the target group L2 ID may also be configured by applying the same method. Accordingly, the UE may identify or recognize the cast type using the L1 ID and/or L2 ID of the source, purpose, or target group.

The method of identifying the cast type in the SCI format is a method of configuring the format of the SCI for transmitting control information such as scheduling information of a sidelink radio channel differently according to the cast type. That is, the cast type may be identified based on the format of the SCI transmitted to or received from the opposite terminal. Accordingly, the attribute (or type) of the parameter(s) constituting the SCI may vary according to the cast type, or the length of the parameter(s) constituting the SCI may vary. For example, when the attribute (or type) of the parameter(s) constituting the SCI is set differently, the SCI for the broadcast method does not include the purpose ID, and the SCI for the groupcast or unicast method is the purpose ID. It can be configured to include. When the length of the parameter(s) constituting the SCI is set differently, the length of the identifier included in the SCI or the length of the bits (or bytes) constituting the SCI may be set differently. In such a case, the cast type may be classified using the SCI format index.

The method of including the indicator information indicating the cast type in the SCI is a method of applying the indicator information indicating the cast type as a field parameter constituting the SCI. For example, in the case of a 2-bit field parameter, '11' may indicate broadcast, '10' may indicate groupcast, and '01' may indicate unicast.

As another method of classifying the cast type, a method of differently setting sidelink radio resources according to the cast type may be applied. That is, a method of differently setting the time axis or frequency axis allocation information of a radio resource through which a sidelink radio channel is transmitted may be applied according to a cast type.

As another method of classifying the cast type, a method of identifying the cast type using the HARQ retransmission method or sidelink radio resource allocation information for transmitting feedback information (NACK or ACK) for HARQ retransmission may be applied. For example, when a sidelink radio resource for transmitting HARQ feedback information is not allocated, a cast type may be identified by a broadcast method. In addition, when radio resources of a sidelink feedback channel (eg, PSFCH (Physical Sidelink Feedback Channel)) capable of transmitting only NACK feedback are allocated, the cast type may be identified in a groupcast method. In addition, when radio resources of a sidelink feedback channel (PSFCH) capable of transmitting both NACK or ACK feedback are allocated, the cast type may be recognized (or identified) in a unicast manner. The information indicating the HARQ retransmission scheme or the allocation information of the sidelink feedback channel for transmitting the feedback information (NACK or ACK) for HARQ retransmission is a control message of the RRC layer for setting the sidelink, a MAC control message for the sidelink, It may be delivered to the terminal using SCI information or a control message (or information) transmitted through a separate physical sidelink control channel (PSCCH). When the radio resources of the sidelink feedback channel for transmitting HARQ feedback information for the sidelink are differently allocated according to the groupcast or unicast method, or the component(s) of the allocation information are different according to the groupcast or unicast method, HARQ The cast type can be identified only by radio resource allocation information of the sidelink feedback channel for transmitting feedback information.

Meanwhile, as described above, when a cast type is indicated (or transmitted) using field information in the SCI, a mapping relationship for the associated PSFCH resource is set based on the cast type indication information of the SCI according to the cast type. I can. That is, whether the UE receiving the SCI including the cast type indication information transmits the feedback information for the PSSCH received as the corresponding SCI information, whether it transmits only NACK feedback for the PSSCH received as the SCI information, or NACK or ACK feedback. Whether to transmit or not, position information of a PSFCH resource for transmitting feedback information, index information of a PSFCH resource, or information indicating a mapping relationship between the cast type indication information of SCI and the PSFCH resource may be obtained. Here, the mapping relationship between the cast type indication information of the SCI and the PSFCH resource may determine the index of the PSFCH resource transmitting the feedback information for the received PSSCH according to the cast type indication information in the SCI. That is, according to the need for HARQ feedback information transmission (e.g., NACK feedback only or NACK/ACK feedback), according to the processing identifier, the source ID of L1 or L2, the purpose ID of L1 or L2, and/or the cast type indication information An index value indicating radio resources of the PSFCH for HARQ feedback transmission may be determined.

Meanwhile, the HARQ feedback-based retransmission of the side link channel is performed only as much as the set maximum number of retransmissions, and the maximum number of retransmissions may be set to the terminal using system information or a dedicated control message. The maximum number of retransmissions for such a side link is the cast type of the sidelink (SL) and/or the sidelink radio resource allocation (or scheduling) method (e.g., a configured grant (CG)) or a dynamic grant. It may be set differently according to (dynamic grant (DG))). Alternatively, the transmitting terminal may instruct the counterpart terminal(s) information on the maximum number of retransmissions or remaining number of retransmissions using the SCI information. In addition, the base station may instruct the terminal(s) of the maximum number of retransmissions or remaining number of retransmissions for the sidelink by using the DCI information.

In the method for classifying a cast type using the aforementioned HARQ retransmission method or radio resource allocation information of a sidelink feedback channel for transmitting feedback information for HARQ retransmission, the terminal is the HARQ retransmission method information of the sidelink radio channel for direct communication. It is possible to obtain information on whether only NACK is transmitted by transmitting HARQ feedback information of the sidelink channel or whether NACK or ACK is transmitted according to a sidelink reception result (ie, a CRC check result). In addition, the terminal may transmit HARQ feedback information on a sidelink channel for a direct communication service by using a corresponding resource indicated in the acquired radio resource allocation information of the sidelink feedback channel.

As another method of classifying the cast type, a method of identifying the cast type of the sidelink channel using a logical channel identifier (LCID: Logical Channel ID) or an LCID group (eg, LCG (Logical Channel Group)) can be applied. have. That is, the LCID range or LCG ID that can be allocated according to the cast type is set, and the base station or the terminal may allocate another LCID or LCG ID according to the cast type information acquired in the parameter setting step for the sidelink channel. Therefore, the transmitting or receiving terminal can identify the cast type only by the LCID or LCG ID.

In order to determine the above-described cast type, the cast type is directly indicated (or indicated) based on the purpose ID, source ID, or bit information, LCID, or LCG ID in the SCI, or the above-described purpose ID, source ID, LCID, Alternatively, configuration information in which the LCG ID is associated (or mapped) to the cast type may be transmitted using a MAC layer or RRC layer control message.

In direct communication using a sidelink radio channel, the scheduling function by the RRC layer and/or MAC entity is performed in consideration of HARQ retransmission. For example, HARQ function and/or HARQ feedback (i.e., ACK/NACK) transmission may be activated or deactivated in units of a logical channel header (LCH), and information indicating such HARQ activation or deactivation may be determined by using SCI. (Or may be delivered to the other terminal (peer UE)). Therefore, when HARQ function and/or HARQ feedback (i.e., ACK/NACK) transmission is activated or deactivated on an LCH basis, resource allocation (or scheduling) for a sidelink radio channel and/or resource allocation for HARQ retransmission is HARQ MAC SDUs composed of only activated LCHs or HARQ deactivated LCHs should be performed so that they can be composed of one MAC PDU. Therefore, triggering and/or transmission of a buffer status report (BSR) or a scheduling request (SR) performed by the terminal, or a function related to logical channel priority (LCP) is whether HARQ for the corresponding LCH is activated. Or, it should be performed in consideration of whether it has been disabled. The LCP-related function should be performed in consideration of activation or deactivation of the HARQ function in units of LCHs belonging to the same purpose ID (eg, a destination L1 ID or a destination L2 ID). For example, a destination ID (a destination L1 ID or a destination L2 ID) with a high-priority LCH is selected, and for LCHs having the same destination ID, the MAC for LCHs having the same attribute according to whether HARQ is activated/deactivated. SDUs are multiplexed onto the same MAC PDU and transmitted.

To this end, a control message (e.g., a PC5 RRC message) for RRC configuration between terminals for direct communication indicates whether HARQ can be activated or deactivated (or set) in LCH (or LCG unit) as control information (or parameter). Can include.

The receiving terminal allocates a HARQ process using the HARQ activation or deactivation information transmitted through the SCI and selects the HARQ process ID. The HARQ process determination and/or HARQ process ID selection may be performed by separating SL (Sidelink) and UL (Uplink).

If, as described above, if the cast type is identified based on the L1 ID and/or L2 ID of the source, destination, or destination group included in the SCI, the L1 ID and/or L2 of the source, destination, or destination group It is possible to indicate whether to activate and/or deactivate HARQ retransmission only by selecting (or assigning) an ID. In this case, depending on whether HARQ retransmission is activated and/or deactivated, a selectable source, a purpose, or an L1 ID and/or L2 ID range or region of a target group may be differently set. In addition, the corresponding control information may be defined in advance in the system, or transmitted to the terminal (or counterpart terminal device) using system information, a dedicated control message, or a PC5-RRC message.

A terminal providing a direct communication service of a base station control method (or mode 1) includes a HARQ operation parameter for a sidelink (SL) channel (eg, HARQ process ID and/or HARQ feedback information) and a Uu interface ( For example, it is possible to set and manage a correspondence relationship for the HARQ operation parameter of (a radio interface between the base station and the terminal). For example, the HARQ process ID transmitted from the counterpart terminal may not be the same as the HARQ process ID transmitted from the terminal to the base station through the Uu interface. Accordingly, a mapping relationship between the HARQ parameter of the SL channel and the DL (downlink) and/or UL (uplink) HARQ parameter of the Uu interface can be set and managed. If such a mapping (or correspondence) relationship is not established, the base station and/or the terminal may exchange the HARQ parameter of the SL channel in the form of MAC CE through the PDSCH or PUSCH channel. In this case, the HARQ process ID on the SL channel, bit information representing one or more ACK/NACK feedback information, or the L1 ID and/or L2 ID of the source, destination, or destination group may be included in the corresponding MAC CE.

In addition, in resource allocation or resource selection of a sidelink channel, whether or not a resource allocated or selected is associated with a sidelink feedback channel may be considered. SL radio resource allocation (allocation) (or scheduling) according to whether the HARQ function and/or HARQ feedback (ie, ACK/NACK) transmission is activated in the scheduling or SL resource selection operation or procedure by the RRC layer and/or MAC entity or Selection can be performed differently. For example, when the HARQ function (or HARQ feedback transmission) is deactivated, resources may be allocated or selected from an SL radio resource pool that is not associated or mapped with a sidelink feedback channel. Meanwhile, when the HARQ function (or HARQ feedback transmission) is activated, a resource may be allocated or selected from an SL radio resource pool associated with or mapped with a sidelink feedback channel. To this end, the SL radio resource pool including radio resources having an association or mapping relationship with the sidelink feedback channel and radio resources that do not have an association or mapping relationship with the sidelink feedback channel The included SL radio resource pool can be set separately. The configuration information for the corresponding radio resource pools may be transmitted to the terminal using system information or control messages. Accordingly, as described above, the base station or the terminal considers the sidelink feedback channel and the association or mapping relationship according to whether the HARQ function (or HARQ feedback transmission) is activated, and the radio resource in the corresponding SL radio resource pool. SL packet can be transmitted by allocating or selecting. Accordingly, the receiving terminal may recognize whether the HARQ function is activated or whether HARQ feedback is transmitted only with the transmitted SL radio resource.

Meanwhile, common control information for providing a sidelink service including SL radio resource configuration information may be set in units of a validity area. This effective area may consist of one or more cells. The valid area for SL radio resource configuration is identified by an SL validity area ID, or other identifier (e.g., a cell identifier, a tracking area ID, a system information area ID). , Zone ID, etc.), or may be identified by an optional combination of the identifier(s).

SL configuration information for the SL BWP, CORESET, and/or the SL radio resource pool for the sidelink service may be set in units of the SL effective area. For example, if the SL effective area is different, SL configuration information for SL BWP, core set, and/or SL radio resource pool may be different. Therefore, even when the serving cell or camping cell is changed, if the SL effective area information (or SL effective area identifier) is the same, the UE provides a sidelink service using the stored SL common configuration information or SL radio resource pool configuration information. It can be done or provided. However, when the effective area is changed, the terminal receiving the sidelink service or the terminal interested in the sidelink service may perform a procedure of updating the SL common configuration information or request transmission of system information necessary to obtain the SL common configuration information. have. Alternatively, when the terminal reports the change of the SL effective area to the base station, the base station may deliver new SL common configuration information to the terminal.

How to set up PC5-RRC connection between terminals

In direct communication using a sidelink radio channel, a radio link setup or management procedure between terminals is required to provide a unicast service.

7 is a flowchart illustrating an embodiment of a method for establishing a connection between terminals for direct communication according to the present invention.

In FIG. 7, the base station 701 and the base station 702 may be base stations of the same operator or base stations operated by different operators. In addition, the terminal 703 and the terminal 704 may be terminals subscribed to the same operator or terminals subscribed to different operators. In addition, the terminals 703 and 704 of FIG. 7 are terminals installed in a vehicle or other types of user terminals (e.g., cellular phones, smart phones, machine type communication (MTC) terminals, or Internet of Thing (IoT) terminals). Etc.). In addition, the base stations 701 and 702 of FIG. 7 and the terminals 703 and 704 may exchange data packets or control signaling messages using the interface described in FIG. 5. For example, the base stations 701 and 702 and the terminals 703 and 704 may use a Uu interface (a radio access interface between a base station and a terminal) of a 3GPP LTE/LTE-A system or an NR system. In addition, data packets or control signaling messages may be exchanged between terminals using a sidelink channel for direct communication (eg, D2D or V2X direct communication).

The terminals 703 and 704 can perform a direct communication function in the connected state (e.g., RRC connected state), the inactive state (e.g., RRC inactive state), or the idle state (RRC idle state) described in FIG. have. For example, the terminal 703 may establish a connection with the base station 701 and, if necessary, receive resources for direct communication from the base station (ie, resource allocation according to the mode 1 scheme described above) (S701). In addition, the terminal 704 may operate in a state of being camped in the base station 704 in an idle state (eg, RRC idle state) without establishing a connection with the base station 702. That is, the terminal 704 checks the resource pool configuration information included in the system information received from the base station 702 or the resource pool configuration information pre-configured from the base station 702 to enable direct communication. It may be in (resource allocation of the mode 2 method described above) (S702).

Connection (e.g., PC5-RRC connection) between terminals that have been assigned resources from the base station by the above-described steps S701 or S702 or can select resources by themselves is largely performed in the sensing/discovery step (S710), the PC5-RRC setting step ( S720) and the PC5-RRC release step (S730).

Sensing/Discovery Step (S710)

The terminals 703 and 704 that are allocated radio resources to the base station or select radio resources from the resource pool through step S701 or S702 may perform a sensing (or discovery) step for direct communication (S710). The sensing/discovery step may be performed for discovery of a peer terminal or sensing for resource selection.

In order to perform the sensing/discovery step in step S710, the terminals 703 and 704 may transmit a specific signal (hereinafter, a sidelink discovery signal (SL-DS) and/or a sensing signal (S711)). The sidelink discovery signal (SL-DS) transmitted by the terminal in step S711 is a sidelink reference signal (SL-RS) having a specific pattern in units of radio resource elements (RE) constituting a sidelink channel. )) or may mean a signal composed of a specific sequence defined for the purpose of sensing/discovery. Such SL-DS is composed of radio resources that are periodically preset by a terminal or a group of terminals supporting a direct communication function. In other words, the SL-DS may be transmitted only in a specific subcarrier region on the frequency axis according to a set period of the time axis, such as the period (or interval) and the subcarrier region (or range). ) Information can be transmitted to the terminal using system information or a separate control message, therefore, a terminal supporting the direct communication function can transmit or monitor the SL-DS in the configured subcarrier area according to a set period. In addition, the SL-DS of step S711 may be configured using the entire (or part) of the target ID or target group ID described above, or may be scrambled by all (or part) of the target ID or target group ID. The transmission period of the SL-DS in step S711 may be set in alignment with the above-described SCI transmission period or a multiple of the SCI transmission period, and the REs through which the SL-DS is transmitted are continuously allocated to radio resources through which SCI is transmitted, or SCI may be allocated to be spaced apart from the radio resource transmitted by a predefined interval.

Meanwhile, in step S711, radio link monitoring (RLM), radio resource management (RRM), radio link failure (RLF), or beam management of a sidelink channel other than SL-DS (e.g., BFR (Beam Only sensing signals for failure recovery)) can be transmitted.

The terminal 703, which is a transmitting terminal, may transmit discovery information (S712). As described above, when the SL-DS and/or the sensing signal is transmitted in step S711, discovery information may be transmitted in step S712. In this case, the discovery information may be transmitted using SCI of the physical layer or may be transmitted using a control message of the MAC layer or the RRC layer. The discovery information may include the L1 or L2 ID (eg, source ID, destination ID, or destination group ID) described above.

In the discovery operation of the terminal for direct communication, the receiving terminal that performs monitoring according to the SL-DS cycle described above has a sidelink channel to be received through the SL-DS (or the other terminal (transmitting terminal)). Presence or not) can be recognized. Alternatively, the receiving terminal may recognize whether there is a sidelink channel to be received by the receiving terminal (or whether a counterpart terminal (transmitting terminal) exists) by monitoring the sensing signal. If the existence of the sidelink channel to be received through the SL-DS or the sensing signal (or the existence of the opposite terminal (transmitting terminal)) is confirmed, the terminal uses the SCI channel for receiving the above-described discovery information or sidelink channel. Can monitor and receive. The terminal may perform a procedure (or process) for obtaining a packet of a sidelink channel transmitted to it through SCI channel reception.

Upon receiving the sidelink discovery signal (step S711) or the sidelink discovery information (step S712) transmitted from the terminal 703, the terminal 704 may transmit a response to sensing or discovery (S713). In step S713, the terminal 704 responds to the peer UE 703 is a signal (or a control message) defined for response to a sensing or discovery signal (or information (eg, control message)). ) Can be transmitted. Alternatively, instead of a separate control message, the terminal 704 may transmit a HARQ feedback message for the received discovery information (eg, a control message) to the terminal 703.

In addition, when all of the terminals 703 and 704 select the radio resource of the sidelink channel in the mode 2 method described above, the possibility of collision in the radio resource selection process can be reduced or avoided through the sensing/discovery step (S710). have.

PC5-RRC connection setup step (S720)

When the sensing/discovery step (S710) including steps S711 to S713 is successfully ended, the terminal 703 and the terminal 704 configure RRC between terminals for direct communication in order to support a unicast or groupcast service. A PC5 RRC setting step (S720) for exchanging a control message (for example, a PC5 RRC connection establishment control message transmitted through an SRB) may be performed. In this case, the terminal 703 and/or the terminal 704 may identify or determine the cast type with the counterpart terminal using the methods for identifying the cast type described above. That is, when the cast type for the counterpart terminal is a unicast method or a groupcast method, a PC5-RRC connection establishment step (S720) with the counterpart terminal may be performed.

In the PC5 RRC connection setup step (S720), the terminal 703 may transmit a control message requesting the PC5 RRC connection setup to the peer UE 704 (S721). The terminal 704 that has received the PC5 RRC configuration request may transmit a PC5 RRC configuration response control message to the peer UE 703 (S722). A control message for accepting or rejecting the PC5 RRC setting may be transmitted as the PC5 RRC setting response control message of step S722. The terminal 703 in the RRC connection state or the inactive state may transmit a control message reporting that the PC5 RRC connection is established to the base station 701 (S723).

In step S721, the RRC control message for setting up the PC5 RRC connection includes terminal capability information, terminal identifier and configuration information, sidelink channel configuration information, version information of the direct communication function standard, and movement state ( Mobility status) information may be included.

Here, the UE's capability information includes whether multiple carriers are supported in support of the direct communication function, frequency bands of multiple carriers, the maximum number of supported multiple carriers, whether MIMO is supported, maximum supportable MIMO configuration information, and transmission power. It may include class information, whether or not the beamforming function is supported, and related TCI configuration information, and/or information on the type of the terminal. Here, the terminal type information means information that can identify whether the terminal is a terminal installed in a vehicle, a general user terminal, an IoT terminal, an MTC terminal, a fixed terminal, or an RSU device.

The identifier and configuration information of the terminal is the identifier information of the terminal for supporting the direct communication function, information on whether a connection with the base station is established, the identifier of the base station to which the terminal is connected or camped, or geographical location information of the terminal. ) Can be included.

The version information of the direct communication function standard may mean version (eg, release version) information of the direct communication function standard of the 3GPP LTE/LTE-A or NR system supported by the terminal. The version information may indicate version information of a direct communication function standard of a new communication system to be defined in the future rather than the 3GPP LTE/LTE-A and NR systems.

The movement state information refers to information that can be used or expressed to recognize the current viewpoint of the terminal or a movement state during a certain time period from the current viewpoint. For example, it may be information such as whether the terminal is a fixed terminal, the average moving speed of the terminal, the time the terminal remains in the current cell, or the number of cells that the terminal belonged to during a certain time period.

The sidelink channel configuration information transmitted through the RRC and/or PC5-RRC control message includes information on a modulation order and coding scheme (eg, modulation order or MCS level, etc.) that the terminal can support, a sidelink bearer identifier, TCI state configuration information, Transmission power information of the sidelink channel, power control information, TA control information from the base station, path loss with the base station (or received signal strength), received signal strength information of the opposite terminal or adjacent terminal, and/or the identifier of the adjacent terminal, or It may include measurement results for adjacent terminals. In addition, an RRC control message and/or a PC5-RRC control message (e.g., a control message including a sidelink radio bearer (SLRB) setting parameter) for setting a sidelink channel for supporting a direct communication function between terminals is a sidelink A sidelink traffic attribute for a radio bearer (SLRB), SL radio resource allocation (or configuration) information, a service identifier of a sidelink, a QoS flow identifier (flow ID), a source and/or destination L2 ID, and the like may be included. . In addition, the terminal in the inactive state can store and use the SLRB configuration information set in the connected state. Alternatively, when the terminal transitions to the inactive state, the SLRB configuration information is transmitted, and the terminal in the inactive state may receive a direct communication service between terminals using the transmitted SLRB configuration information. The SLRB configuration information for the terminal in such an inactive state includes SL radio resource allocation (or configuration) information, synchronization configuration type information (e.g., a synchronization criterion allowed for use of the SL radio resource pool). (information indicating a synchronization reference)), etc. may be included. The base station may instruct the terminal to transition to the inactive state and transmit the SLRB configuration information. Alternatively, the base station may deliver a control message including SLRB configuration information to be used in an inactive state when establishing an RRC connection with the terminal.

In addition, a terminal that desires or is interested in a direct communication service between terminals using a sidelink channel may use sidelink traffic properties (e.g., traffic period, transmission interval, message size, SL traffic or cast type), sidelink service identifier, SLRB identifier, SL logical channel identifier (LCID), QoS flow identifier (flow ID), or source and/or destination L2 ID information, etc. can be transmitted to the base station using a terminal assistance information (e.g., UE assistance information) message. have. The UE assistance information message may be transmitted while being included in a control message exchanged at the time of state transition of the UE, a connection request control message, or another RRC layer control message, or may be transmitted using an RRC control message composed of only UE assistance information.

Performing direct communication between terminals (S730)

The terminals 703 and 704 having completed the PC5 RRC configuration in step S721 may perform direct communication in a unicast (or groupcast) method using a sidelink channel (S730).

In the step S730 in which the terminals 703 and 704 directly communicate, the terminals 703 and 704 control the transmission power for the sidelink channel, and perform a TCI state setting and control operation for transmission/reception beam management. can do. In order to control transmission power, the terminal may estimate (or measure) the reception strength or path loss of the reference signal transmitted by the opposite terminal. In order to measure the reception strength or path loss of the reference signal of the sidelink channel between the terminals 703 and 704, the terminals may exchange geographical location information with each other. The path loss may be measured using the acquired location information of the counterpart terminal device and its own location information, or a transmission power value determined based on the received strength of the measured reference signal may be adjusted.

PC5-RRC disconnection step (S740)

The PC5-RRC release step (S740) may be performed by at least one side of the terminals 703 and 704 performing direct communication. Hereinafter, an example in which the terminal 704 requests to cancel the PC5-RRC setting will be described. However, the terminal 703 may request to release the PC5-RRC connection setting.

After completing the direct communication in step S730, the terminal 704 may transmit a control message requesting the release of the PC5 RRC connection setting to the peer UE 703 (S731). Upon receiving the control message requesting the RRC connection setting release, the terminal 703 may transmit a PC5 RRC connection setting release response message to the counterpart terminal 704 (S732). Or, if the PC5 RRC connection setting release response message of step S732 is not received until the preset timer (eg, PC5_Release_Timer) expires after transmitting the PC5 RRC connection setting release request control message of step S731, the terminal 704 Can release the PC5 RRC setting. The PC5_Release_Timer may be started when the terminal 704 transmits a PC5 RRC connection establishment release request message.

The terminal 703 in the RRC connection state or the inactive state may transmit a control message reporting that the PC5 RRC connection setup is released to the base station 701 (S733). Meanwhile, even when the terminal 703 requests to release the PC5-RRC connection setting, the terminal 703 may transmit a control message reporting that the PC5 RRC connection setting has been released to the base station 701.

In the procedure for establishing a connection between terminals for direct communication described in FIG. 7, not all steps of steps S701 to 733 may be necessary to provide a direct communication service using a sidelink channel. That is, only a part of the steps S701 to 733 are performed, so that a direct communication service between terminals may be provided.

Meanwhile, when beam failure detection (BFD), beam failure recovery (BFR), or radio link failure (RLF) for a sidelink channel occurs, the terminal uses the Uu interface. Thus, it is possible to transmit control information notifying the corresponding situation to the base station. Such control information may be transmitted in the form of a field parameter of a physical layer control channel, a MAC CE, or a control message of an RRC layer. When the control information is transmitted as a MAC CE or RRC message, the corresponding control message may include BFD, BFR, or RLF occurrence destination ID, SLRB ID, and/or occurrence time information. Alternatively, a separate LCID is allocated to the MAC CE for the control information, and a MAC CE to which a separate LCID is allocated may be transmitted. Alternatively, only the LCID indicating BFD, BFR, or RLF can be transmitted without MAC CE. Or, when BFD, BFR, or RLF occurs, the terminal sends the BFD, BFR, and/or BFD, BFR, Alternatively, the occurrence of RLF can be notified. At this time, the base station may determine that BFD, BFR, or RLF has occurred in the corresponding sidelink channel when information on the destination ID and SLRB ID is not received from the terminal for a predetermined time interval or a predetermined number of times. Here, the control information reported periodically or aperiodically may be control information transmitted from the terminal to the base station for maintenance of the sidelink channel and/or service continuation. For example, the control information reported periodically or aperiodically may be CSI/CQI report, HARQ feedback information, and/or Buffer Status Report (BSR) for the sidelink channel.

The base station receiving control information notifying the BFD, BFR, or RLF of the sidelink channel in an explicit or implicit method from the terminal releases the SLRB configuration or SL radio resource allocation for the sidelink channel of the terminal. Or, control information for deactivation can be delivered to the corresponding terminal.

Upon receiving the control information instructing release or deactivation of the sidelink channel, the terminal may restart the sidelink service by performing a sidelink reconfiguration procedure or selecting a radio resource in a distributed control method (eg, a mode 2 method).

The start (or restart) time or end or stop time of the timer, counter, offset, interval, or period described above may be set in units of symbols, minislots, slots, subframes, or frames.

The cell (or base station) of the present invention is a NodeB, an evolved NodeB, a base transceiver station (BTS), a radio base station, and a radio transceiver like the base station described in FIG. ), access point, access node, as well as roadside unit (RSU), radio remote head (RRH), transmission point (TP), transmission & reception point (TRP), or gNB And the like.

In addition, the terminal device of the present invention, like the UE described in FIG. 1, is a terminal, an access terminal, a mobile terminal, a station, a subscriber station, and a mobile station. station, portable subscriber station, node, device, as well as Internet of Things (IoT), mounted module/device/terminal or on board device/terminal Etc.).

The methods according to the present invention may be implemented in the form of program instructions that can be executed through various computer means and recorded in a computer-readable medium. The computer-readable medium may include program instructions, data files, data structures, and the like alone or in combination. The program instructions recorded on the computer-readable medium may be specially designed and configured for the present invention, or may be known and usable to those skilled in computer software.

Examples of computer-readable media include hardware devices specially configured to store and execute program instructions, such as ROM, RAM, flash memory, and the like. Examples of program instructions include not only machine language codes such as those produced by a compiler, but also high-level language codes that can be executed by a computer using an interpreter or the like. The above-described hardware device may be configured to operate as at least one software module to perform the operation of the present invention, and vice versa.

Although described with reference to the above embodiments, those skilled in the art will understand that various modifications and changes can be made to the present invention without departing from the spirit and scope of the present invention described in the following claims. I will be able to.

Claims (20)

A method of establishing a connection for direct communication between terminals performed in the terminal,
Transmitting a sensing signal or a sidelink discovery signal;
Transmitting sidelink discovery information;
Receiving a response to the sidelink discovery signal or the sidelink discovery information from a counterpart terminal;
When the cast type of the counterpart terminal is determined, and the cast type is determined by the unicast method or the groupcast method, a PC5-RRC (radio resource control) connection with the counterpart terminal is established. Setting up; And
Including the step of performing direct communication between the counterpart terminal and the terminal,
How to establish a connection. The method according to claim 1,
Establishing an RRC connection with a base station; And
Further comprising the step of receiving allocation of radio resources from the base station,
The sensing signal or the sidelink discovery signal is transmitted through the radio resource,
How to establish a connection. The method according to claim 1,
Further comprising the step of checking a preset radio resource pool or receiving configuration information of the radio resource pool from the base station,
The sensing signal or the sidelink discovery signal is transmitted through a radio resource selected from the radio resource pool,
How to establish a connection. The method according to claim 1,
The sensing signal is a signal for radio link monitoring (RLM, radio link monitoring), radio resource management (RRM), radio link failure (RLF, radio link failure) detection, or beam management,
How to establish a connection. The method according to claim 1,
The sidelink discovery signal is a reference signal having a specific pattern or a signal composed of a specific sequence,
How to establish a connection. The method according to claim 1,
The sidelink discovery signal is transmitted in a preset subcarrier area according to a preset period, and the preset period and/or a preset subcarrier area is received from the base station using system information or a control message. felled,
How to establish a connection. The method according to claim 1,
The discovery information includes an L1 (layer 1) or L2 (layer 2) identifier (ID, identifier) of a source terminal, an L1 or L2 identifier of a target terminal, and/or an L1 or L2 identifier of a target terminal group,
How to establish a connection. The method according to claim 1,
The cast type is identified by the L1 or L2 ID of the source terminal, the L1 or L2 ID of the target terminal, and/or the L1 or L2 ID of the target terminal group, or SCI transmitted to the counterpart terminal or received from the counterpart terminal ( sidelink control information) or identified by an indicator included in the SCI, or identified based on radio resource allocation information for transmitting HARQ retransmission method for the counterpart terminal or HARQ feedback information for the counterpart terminal,
How to establish a connection. The method according to claim 1,
The step of establishing the PC5-RRC connection with the counterpart terminal
Transmitting a control message requesting PC5-RRC connection establishment to the counterpart terminal; And
Receiving a response message for accepting or rejecting the PC5-RRC connection establishment from the counterpart terminal,
How to establish a connection. The method of claim 9,
The control message requesting the PC5-RRC connection establishment includes the capability information of the terminal, the identifier and configuration information of the terminal, sidelink channel configuration information, version information of the direct communication function standard, and movement status. Including at least one of (mobility status) information,
How to establish a connection. A method of establishing a connection for direct communication between terminals performed in the terminal,
Monitoring a sensing signal or a sidelink discovery signal;
Receiving sidelink discovery information from an opposite terminal;
Transmitting the sidelink discovery signal or a response to the sidelink discovery information;
Establishing a PC5-RRC connection with the counterpart terminal; And
Including the step of performing direct communication between the counterpart terminal and the terminal,
How to establish a connection. The method of claim 11,
The terminal recognizes the counterpart terminal through monitoring of the sensing signal or the discovery signal, and receives the sidelink discovery information from the counterpart terminal,
How to establish a connection. The method of claim 11,
The sensing signal is a signal for radio link monitoring (RLM, radio link monitoring), radio resource management (RRM), radio link failure (RLF, radio link failure) detection, or beam management,
How to establish a connection. The method of claim 11,
The sidelink discovery signal is a reference signal having a specific pattern or a signal composed of a specific sequence,
How to establish a connection. The method of claim 11,
The sidelink discovery signal is received in a preset subcarrier area according to a preset period, and the preset period and/or a preset subcarrier area is received from the base station using system information or a control message. felled,
How to establish a connection. The method of claim 11,
The discovery information includes an L1 (layer 1) or L2 (layer 2) identifier (ID, identifier) of a source terminal, an L1 or L2 identifier of a target terminal, and/or an L1 or L2 identifier of a target terminal group,
How to establish a connection. As a terminal that performs direct communication between terminals,
Processor;
A memory in electronic communication with the processor; And
Including instructions executed by the processor and stored in the memory,
When the instructions are executed by the processor, the terminal
Transmitting a sensing signal or a sidelink discovery signal;
Transmitting sidelink discovery information;
Receiving a response to the sidelink discovery signal or the sidelink discovery information from a counterpart terminal;
When the cast type of the counterpart terminal is determined, and the cast type is determined by the unicast method or the groupcast method, a PC5-RRC (radio resource control) connection with the counterpart terminal is established. Setting up; And
To perform the step of performing direct communication between the counterpart terminal and the terminal,
Terminal. The method of claim 17,
The sidelink discovery signal is a reference signal having a specific pattern or a signal composed of a specific sequence,
Terminal. The method of claim 17,
The sidelink discovery signal is transmitted in a preset subcarrier area according to a preset period, and the preset period and/or a preset subcarrier area is received from the base station using system information or a control message. felled,
Terminal. The method of claim 17,
The cast type is identified by the L1 or L2 ID of the source terminal, the L1 or L2 ID of the target terminal, and/or the L1 or L2 ID of the target terminal group, or SCI transmitted to the counterpart terminal or received from the counterpart terminal ( sidelink control information) or identified by an indicator included in the SCI, or identified based on radio resource allocation information for transmitting HARQ retransmission method for the counterpart terminal or HARQ feedback information for the counterpart terminal,
Terminal.

Images