KR20210086225A - Method and apparatus for selecting sidelink frequency resource in wireless communication system - Google Patents

Abstract

The present disclosure relates to a method and device of selecting a side link frequency resource in a wireless communication system. According to one embodiment of the present disclosure, the method for a transmitter terminal to select a side link frequency resource in a wireless communication system includes the following steps of: triggering the selection of a frequency resource with respect to a side link logic channel; determining frequency resource candidates, based on the priority of the side link logic channel or at least one parameter related with at least one frequency resource set for the side link logic channel; selecting at least one frequency resource among the determined frequency resource candidates; and performing transmission to a receiver terminal on the selected frequency resource. The at least one parameter can include at least one among complexity, a geographical element, a link quality, and feedback information.

Description

Method and apparatus for selecting a sidelink frequency resource in a wireless communication system {METHOD AND APPARATUS FOR SELECTING SIDELINK FREQUENCY RESOURCE IN WIRELESS COMMUNICATION SYSTEM}

The present disclosure relates to a method and apparatus for selecting a sidelink frequency resource in a wireless communication system.

3GPP (3rd Generation Partnership Project) NR (New Radio) system is a time-frequency resource unit in consideration of various scenarios, service requirements, potential system compatibility, etc. in order to meet requirements for 5G (5G) communication Various numerologies of criteria can be supported. In addition, the NR system has a plurality of channels in order to overcome a poor channel environment such as high path-loss, phase-noise, and frequency offset occurring on a high carrier frequency. It is possible to support transmission of a physical signal or a physical channel through a beam of Through this, the NR system can support applications such as enhanced mobile broadband (eMBB), massive machine type communications (mMTC), ultra machine type communications (uMTC), and ultra-reliable and low latency communications (URLLC).

V2X (Vehicle-to-X; Vehicle-to-Everything) communication refers to a communication method that exchanges or shares information such as traffic conditions while communicating with road infrastructure and other vehicles while driving. V2X stands for LTE (Long Term Evolution)/NR based communication between vehicles, V2V (vehicle-to-vehicle), and V2P (vehicle-to-vehicle) refers to LTE/NR based communication between a vehicle and a terminal carried by an individual. pedestrian), vehicle-to-infrastructure/network (V2I/N), which means LTE/NR-based communication between a vehicle and a roadside unit (RSU)/network. Here, the RSU may be a transport infrastructure entity implemented by a base station or a fixed terminal, for example, an entity that transmits a speed notification to a vehicle. In addition, V2X communication is a method using a PC5 link (or sidelink, SL), which is a terminal-to-terminal (D2D) communication interface, and a Uu link (or uplink) and downlink that is a communication interface between the base station and the terminal It may include a method using a link (downlink), or a method using both a PC5 link and a Uu link.

In the V2X technology discussed so far, only one frequency resource can be used in NR SL. For example, the frequency resource may be a carrier and/or a bandwidth part (BandWidth Part, BWP). However, in order to provide a higher data transmission rate, a variety of connections, and flexibility in using a frequency spectrum, a technology supporting NR SL data transmission/reception on one or more carriers/BWPs rather than one carrier/BWP as in the prior art is required. More specifically, when one or more SL carriers/BWPs are configured or provided to an NR SL terminal, a specific method for selecting or reselecting a carrier/BWP for NR SL transmission has not yet been prepared.

It is an object of the present disclosure to provide a method and apparatus for selecting or reselecting a frequency resource on an NR sidelink.

A further technical problem of the present disclosure is to provide a method and apparatus for selecting or reselecting a frequency resource on an NR sidelink based on a combination of one or more parameters.

The technical problems to be achieved in the present disclosure are not limited to the technical problems mentioned above, and other technical problems not mentioned will be clearly understood by those of ordinary skill in the art to which the present disclosure belongs from the description below. will be able

A method for a transmitting terminal to select a sidelink frequency resource in a wireless communication system according to an aspect of the present disclosure includes: triggering frequency resource selection for a sidelink logical channel; determining a frequency resource candidate based on one or more parameters related to one or more of a priority of the sidelink logical channel or a frequency resource configured for the sidelink logical channel; selecting one or more frequency resources from among the determined frequency resource candidates; and performing transmission to the receiving terminal on the selected frequency resource, wherein the one or more parameters may include one or more of congestion degree, geographic factor, link quality, and feedback information.

The features briefly summarized above with respect to the present disclosure are merely exemplary aspects of the detailed description of the present disclosure that follows, and do not limit the scope of the present disclosure.

According to the present disclosure, a method and apparatus for determining a frequency resource candidate satisfying QoS characteristics required in an NR sidelink may be provided.

According to the present disclosure, a method and apparatus may be provided for selecting a frequency resource suitable for an NR sidelink by using a combination of one or more parameters related to a priority of a logical channel of data to be transmitted in the NR sidelink.

Effects obtainable in the present disclosure are not limited to the above-mentioned effects, and other effects not mentioned may be clearly understood by those of ordinary skill in the art to which the present disclosure belongs from the description below. will be.

1 is a diagram for explaining an NR frame structure to which the present disclosure can be applied.
2 is a diagram illustrating an NR resource structure to which the present disclosure can be applied.
3 is a diagram illustrating an NR sidelink slot structure to which the present disclosure can be applied.
4 is a diagram illustrating an NR sidelink frequency to which the present disclosure can be applied.
5 is a flowchart for explaining an example of a frequency resource selection method to which the present disclosure can be applied.
6 is a flowchart for explaining an additional example of a frequency resource selection method to which the present disclosure can be applied.
7 is a diagram illustrating the configuration of a first terminal device and a second terminal device according to the present disclosure.

Hereinafter, with reference to the accompanying drawings, the embodiments of the present disclosure will be described in detail so that those of ordinary skill in the art to which the present disclosure pertains can easily implement them. However, the present disclosure may be embodied in several different forms and is not limited to the embodiments described herein.

In describing the embodiments of the present disclosure, if it is determined that a detailed description of a well-known configuration or function may obscure the gist of the present disclosure, a detailed description thereof will be omitted. And, in the drawings, parts not related to the description of the present disclosure are omitted, and similar reference numerals are attached to similar parts.

In the present disclosure, when a component is "connected", "coupled" or "connected" to another component, it is not only a direct connection relationship, but also an indirect connection relationship in which another component exists in the middle. may also include. In addition, when a component is said to "include" or "have" another component, it means that another component may be further included without excluding other components unless otherwise stated. .

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

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

In the present disclosure, components described in various embodiments do not necessarily mean essential components, and some may be optional components. Accordingly, an embodiment composed of a subset of components described in one embodiment is also included in the scope of the present disclosure. In addition, embodiments including other components in addition to components described in various embodiments are also included in the scope of the present disclosure.

The present disclosure describes a wireless communication network as a target, and an operation performed in the wireless communication network is performed in the process of controlling the network and transmitting or receiving a signal in a system (eg, a base station) having jurisdiction over the wireless communication network, or This may be done in the process of transmitting or receiving a signal from a terminal coupled to a wireless network.

It is obvious that various operations performed for communication with a terminal in a network including a plurality of network nodes including a base station may be performed by the base station or other network nodes other than the base station. 'Base station (BS: Base Station)' may be replaced by terms such as fixed station, Node B, eNodeB (eNB), ng-eNB, gNodeB (gNB), and access point (AP). . In addition, 'terminal' may be replaced with terms such as User Equipment (UE), Mobile Station (MS), Mobile Subscriber Station (MSS), Subscriber Station (SS), and non-AP station. can

In the present disclosure, transmitting or receiving a channel includes the meaning of transmitting or receiving information or a signal through a corresponding channel. For example, transmitting the control channel means transmitting control information or a signal through the control channel. Similarly, to transmit a data channel means to transmit data information or a signal over the data channel.

Definitions for abbreviations used in the present disclosure are as follows.

D2D: Device to Device (communication)

ProSe: (Device to Device) Proximity Services

PSBCH: Physical Sidelink Broadcast Channel

PSCCH: Physical Sidelink Control Channel

PSDCH: Physical Sidelink Discovery Channel

PSFCH: Physical Sidelink Feedback Channel

PSSCH: Physical Sidelink Shared Channel

SCI: Sidelink Control Information

SFCI: Sidelink Feedback Control Information

SL: Sidelink

SLSS: Sidelink Synchronization Signal

QoS: Quality of Service

5QI: 5G QoS Indicator

PQI: PC5 QoS Indicator

CBR: Channel Busy Ratio

LC: Logical Channel

The 5G system may be defined as including all of the existing Long Term Evolution (LTE)-based systems as well as the NR system. That is, the 5G system may include not only the case where the NR radio access technology is applied alone, but also the case where the LTE-based radio access technology and the NR radio access technology are applied together. In addition, the 5G sidelink technology can be said to include all of the sidelink technologies to which NR alone or LTE series and NR are applied together.

Hereinafter, the physical resource structure of the NR system will be described.

1 is a diagram for explaining an NR frame structure to which the present disclosure can be applied.

일 수 있고,

이고,

일 수 있다. 한편, LTE에서 시간 도메인 기본 단위는

일 수 있고,

이고,

일 수 있다. NR 시간 기본 단위와 LTE 시간 기본 단위 사이의 배수 관계에 대한 상수는

로서 정의될 수 있다.The basic unit of time domain in NR is

can be,

ego,

can be Meanwhile, in LTE, the basic unit of time domain is

can be,

ego,

can be The constant for the multiple relationship between the NR time base unit and the LTE time base unit is

can be defined as

를 가질 수 있다. 이때, 하나의 프레임은

시간에 해당하는 10개의 서브프레임으로 구성된다. 서브프레임마다 연속적인 OFDM 심볼의 수는

일 수 있다. 또한, 각 프레임은 동일한 크기의 2개의 하프 프레임(half frame)으로 나누어지며, 하프 프레임 1은 서브 프레임 0-4로 구성되고, 하프 프레임 2는 서브 프레임 5-9로 구성될 수 있다.Referring to FIG. 1, the time structure of a frame for DL/UL transmission is

can have In this case, one frame

It consists of 10 subframes corresponding to time. The number of consecutive OFDM symbols per subframe is

can be In addition, each frame may be divided into two half frames of the same size, half frame 1 may include subframes 0-4, and half frame 2 may include subframes 5-9.

는 하향링크(DL)와 상향링크(UL) 간의 타이밍 어드밴스(TA)를 나타낸다. 이때, 상향링크 전송 프레임 i의 전송 타이밍은 단말에서 하향링크 수신 타이밍을 기반으로 아래의 수학식 1에 기초하여 결정된다.Referring to Figure 1,

denotes a timing advance (TA) between the downlink (DL) and the uplink (UL). In this case, the transmission timing of the uplink transmission frame i is determined based on the downlink reception timing in the terminal based on Equation 1 below.

은 듀플렉스 모드 (duplex mode) 차이 등으로 발생하는 TA 오프셋 (TA offset) 값일 수 있다. 기본적으로 FDD (Frequency Division Duplex)에서

은 0 값을 가지지만, TDD (Time Division Duplex)에서는 DL-UL 스위칭 시간에 대한 마진을 고려해서

의 고정된 값으로 정의될 수 있다.in Equation 1

may be a TA offset value generated due to a duplex mode difference or the like. Basically in FDD (Frequency Division Duplex)

has a value of 0, but in TDD (Time Division Duplex), considering the margin for DL-UL switching time,

can be defined as a fixed value of .

2 is a diagram illustrating an NR resource structure to which the present disclosure can be applied.

A resource element (RE) in a resource grid may be indexed according to each subcarrier spacing. In this case, one resource grid may be generated for each antenna port and for each subcarrier spacing. Uplink and downlink transmission and reception may be performed based on a corresponding resource grid.

)를 구성할 수 있다. RB에 대한 인덱스는 특정 주파수 대역 또는 시스템 대역폭 내에서 활용될 수 있다. RB에 대한 인덱스는 아래의 수학식 2와 같이 정의될 수 있다. 여기서,

는 하나의 RB 당 서브캐리어의 개수를 의미하고, k는 서브캐리어 인덱스를 의미한다.One resource block (RB) in the frequency domain consists of 12 REs, and an index (

) can be configured. The index for the RB may be utilized within a specific frequency band or system bandwidth. The index for the RB may be defined as in Equation 2 below. here,

denotes the number of subcarriers per one RB, and k denotes a subcarrier index.

Numerology can be configured in various ways to satisfy various services and requirements of the NR system. Table 1 below shows examples of pneumatology supported by the NR system.

Referring to Table 1, the numerology may be defined based on subcarrier spacing (SCS), cyclic prefix (CP) length and the number of OFDM symbols per slot used in an orthogonal frequency division multiplexing (OFDM) system. have. The above-described values may be provided to the UE through higher layer parameters DL-BWP-mu and DL-BWP-cp for downlink and higher layer parameters UL-BWP-mu and UL-BWP-cp for uplink. have.

)가 2인 경우, 서브캐리어 스페이싱(

)은 60kHz이고, 노멀 CP 및 확장 CP(Extended CP)가 적용될 수 있다. 그 외의 뉴머롤러지 인덱스의 경우에는 노멀 CP만 적용될 수 있다.As an example, in Table 1, the subcarrier spacing setting index (

) is 2, the subcarrier spacing (

) is 60 kHz, and a normal CP and an extended CP may be applied. In the case of other numerical indexes, only the normal CP may be applied.

In this case, the normal slot may be defined as a basic time unit used to basically transmit one piece of data and control information in the NR system. The length of the normal slot may be basically composed of the number of 14 OFDM symbols. In addition, unlike the slot, the subframe has an absolute time length corresponding to 1 ms in the NR system, and may be used as a reference time for the length of another time interval. In this case, for the coexistence or backward compatibility of LTE and the NR system, a time interval such as a subframe of LTE may be required for the NR standard.

For example, in LTE, data may be transmitted based on a Transmission Time Interval (TTI), which is a unit time, and the TTI may be configured in units of one or more subframes. In this case, even in LTE, one subframe may be set to 1 ms, and 14 OFDM symbols (or 12 OFDM symbols) may be included.

In addition, a non-slot may be defined in NR. The non-slot may mean a slot having a number smaller than the normal slot by at least one symbol. For example, when a low delay time is provided as in the URLLC service, the delay time may be reduced through a non-slot having a smaller number of symbols than a normal slot. In this case, the number of OFDM symbols included in the non-slot may be determined in consideration of the frequency range. For example, in a frequency range of 6 GHz or more, a non-slot of 1 OFDM symbol length may be considered. As another example, the number of OFDM symbols defining a non-slot may include at least two OFDM symbols. In this case, the range of the number of OFDM symbols included in the non-slot may be configured as the length of the mini-slot up to the normal slot length-1. However, as a non-slot standard, the number of OFDM symbols may be limited to 2, 4, or 7 symbols, but is not limited to the above-described embodiment.

가 1 및 2에 해당하는 서브캐리어 스페이싱이 사용되고, 6GHz 초과의 비면허 대역에서는

가 3 및 4에 해당하는 서브캐리어 스페이싱이 사용될 수 있다. 이때, 일 예로,

가 4인 경우는 SSB(Synchronization Signal Block)를 위해서 사용될 수도 있다.In addition, as an example, in the unlicensed band of 6 GHz or less,

Subcarrier spacing corresponding to 1 and 2 is used, and in unlicensed bands above 6 GHz,

Subcarrier spacing corresponding to 3 and 4 may be used. At this time, for example,

When is 4, it may be used for a Synchronization Signal Block (SSB).

)별로, 노멀 CP의 경우의 슬롯 당 OFDM 심볼 개수(

), 프레임 당 슬롯 개수(

), 서브프레임 당 슬롯의 개수(

)를 나타낸다. 표 2에서는 14개의 OFDM 심볼을 갖는 노멀슬롯을 기준으로 상술한 값들을 나타낸다.Table 2 shows the subcarrier spacing settings (

), the number of OFDM symbols per slot in the case of normal CP (

), number of slots per frame (

), the number of slots per subframe (

) is indicated. Table 2 shows the above-described values based on a normal slot having 14 OFDM symbols.

가 2인 경우로서 서브캐리어 스페이싱이 60kHz일 때), 슬롯 당 OFDM 심볼 개수가 12인 노멀슬롯을 기준으로 프레임 당 슬롯의 수 및 서브프레임당 슬롯의 수를 나타낸다.Table 3 shows when extended CP is applied (that is,

is 2 (when subcarrier spacing is 60 kHz), indicates the number of slots per frame and the number of slots per subframe based on a normal slot in which the number of OFDM symbols per slot is 12.

Hereinafter, the V2X service will be described.

In V2X communication, control information transmitted by a terminal to another terminal may be referred to as an SA. When a sidelink (hereinafter SL) is used as a communication link between terminals, the control information may be referred to as SCI. In this case, the control information may be transmitted through the PSCCH.

In V2X communication, data transmitted by a terminal to another terminal may be configured in a transport block (TB) unit. In this case, the data may be transmitted through the PSSCH.

In addition, in the present disclosure, an operation mode is defined according to a resource allocation method for transmitting control information and data for V2X communication or direct link (eg, D2D, ProSe, or SL) communication.

In the base station resource scheduling mode, a base station or a relay node schedules resources used by the terminal to transmit V2X (or direct link) control information and/or data, and accordingly, the terminal schedules the V2X (or direct link) It means a mode for transmitting control information and/or data. For example, the base station or the relay node transmits the V2X (or direct link) control information and/or scheduling information for a resource to be used for data transmission through the downlink control information (DCI) to V2X (or direct link) It can be provided to the transmitting terminal. Accordingly, the V2X (or direct link) transmitting terminal transmits V2X (or direct link) control information and data to the V2X (or direct link) receiving terminal, and the V2X (or direct link) receiving terminal is V2X (or direct link) It is possible to receive V2X (or direct link) data based on the control information.

On the other hand, in the terminal autonomous resource selection mode, the terminal selects the resources used by the terminal to transmit the control information and data, and this resource selection is performed by the terminal in a resource pool (ie, a set of resource candidates). It is determined by sensing, etc., and means a mode in which the terminal transmits the control information and data accordingly. For example, the V2X (or direct link) transmitting terminal transmits V2X (or direct link) control information and data to the V2X (or direct link) receiving terminal in the resource selected by the V2X (or direct link) receiving terminal, and the V2X (or direct link) receiving terminal is Based on the V2X (or direct link) control information, V2X (or direct link) data may be received.

Hereinafter, embodiments of the present invention will be described by taking V2X communication as an example, but the scope of the present invention is not limited to V2X communication, and embodiments of the present invention are applied to direct link-based communication such as D2D, ProSe, SL communication. can

In LTE, communication from a base station to a terminal is downlink (DL), and communication from a terminal to a base station is called uplink (UL). In addition to the uplink and downlink, communication from the terminal to the terminal is defined and called as a sidelink (SL).

The first technology item applied by using PC5-based sidelink communication in LTE is D2D, which is public safety and proximity communication (Prose) for commercial purposes. After that, the next technology item after applying the PC5-based sidelink communication in LTE is V2X, which is communication targeting vehicles.

Existing V2X service (eg, LTE Rel-14 V2X) may support a set of basic requirements for V2X services. At this time, the requirements are basically designed by sufficiently considering the road safety service. Therefore, V2X UE (User Equipment) can exchange their state information through a sidelink (Sidelink), and exchange the above-mentioned information with infrastructure nodes and/or pedestrians. can

In a more advanced V2X service (eg, LTE Rel-15 V2X), carrier aggregation in the sidelink (carrier aggregation, CA), high order modulation (high order modulation), delay reduction (latency reduction), transmit diversity New features were introduced in consideration of the feasibility of (Tx diversity) and sTTI (shortened TTI). Based on the above, coexistence with V2X UEs (same resource pool) was required, and the above-described services were provided based on LTE.

As an example, in consideration of use cases for supporting a new V2X service as SA (System Aspect) 1, technical features may be classified based on four categories as shown in Table 4 below. In this case, in Table 4, Vehicles Platooning may be a technique in which a plurality of vehicles dynamically form a group and similarly operate. In addition, extended sensors may be a technology for collecting and exchanging data acquired from a sensor or a video image. In addition, advanced driving may be a technology in which a vehicle is driven based on full automation or semi-automation. In addition, remote driving may be a technology that provides a technology and an application for remote control of a vehicle. For more detailed information on this, refer to Table 4 below.

- Vehicles Platooning
Vehicles Platooning enables the vehicles to dynamically form a platoon traveling together. All the vehicles in the platoon obtain information from the leading vehicle to manage this platoon. These information allow the vehicles to drive closer than normal in a coordinated manner, going to the same direction and traveling together. - Extended Sensor Extended Sensor enables the exchange of raw or processed data gathered through local sensors or live video images among vehicles, road site units, devices of pedestrian and V2X application servers. The vehicles can increase the perception of their environment beyond of what their own sensors can detect and have a more broad and holistic view of the local situation. High data rate is one of the key characteristics. - Advanced DrivingAdvanced Driving enables semi-automated or full-automated driving. Each vehicle and/or RSU shares its own perception data obtained from its local sensors with vehicles in proximity and that allows vehicles to synchronize and coordinate their trajectories or manoeuvres. Each vehicle shares its driving intention with vehicles in proximity too. - Remote DrivingRemote Driving enables a remote driver or a V2X application to operate a remote vehicle for those passengers who cannot drive by themselves or remote vehicles located in dangerous environments. For a case where variation is limited and routes are predictable, such as public transportation, driving based on cloud computing can be used. High reliability and low latency are the main requirements.

In addition, the NR sidelink may be a concept including both a sidelink based on the existing LTE system and a sidelink considering the NR system. That is, the service may be provided in consideration of the sidelink applied in each system, and is not limited to the above-described embodiment.

For example, the above-described SA1 may be considered both LTE and NR as an advanced V2X (enhanced V2X, eV2X) support technology for supporting a new V2X service. As an example, the NR V2X system may be the first V2X system. In addition, the LTE V2X system may be a second V2X system. That is, the NR V2X system and the LTE V2X system may be different V2X systems. Hereinafter, embodiments according to the present disclosure in the NR sidelink based on the NR V2X system will be described. However, the same or similar configuration may be extended and applied to the LTE V2X system, and embodiments of the present disclosure are not limited to the NR V2X system. That is, the LTE V2X system may also be applied to the interoperable part, and embodiments of the present disclosure are not limited to the NR V2X system. As an example, NR V2X capability may not necessarily be limited to support only V2X services, and what V2X RAT (Radio Access Technology) to use may be selected.

Hereinafter, NR V2X sidelink physical channels, signals, basic slot structures and physical resources will be described.

NR PSSCH means a physical layer NR SL data channel.

The NR PSCCH refers to a physical layer NR SL control channel, and corresponds to a channel for transmitting control information (eg, SCI) including scheduling information of the NR SL data channel. The SCI may include information necessary for decoding the corresponding PSSCH, and one or more SCI formats may be defined.

NR PSFCH refers to a physical layer NR HARQ (Hybrid Automatic Repeat reQuest)-feedback channel, and corresponds to a channel for delivering information (eg, SFCI) such as HARQ-ACK feedback corresponding to the NR SL data channel. . HARQ-ACK feedback information and the like in the sidelink may be defined for unicast and groupcast cases. In addition, the SFCI may be transmitted through the PSFCH or may be transmitted through the PSSCH. The SFCI may include HARQ-ACK information for the corresponding PSSCH, and one or more SFCI formats may be defined.

Meanwhile, CSI (Channel State Information) for NR V2X may be transmitted through PSSCH. For example, sidelink CSI such as Channel Quality Indicator (CQI)/Rank Indicator (RI) information is configured in the form of a MAC CE (Medium Access Control Control Element) and transmitted using a data channel (ie, PSSCH), The same resource allocation method as data may be applied.

The NR SLSS/PSBCH block means a synchronization and broadcast channel block in which an NR SL synchronization signal and a broadcast channel are transmitted over one continuous time in a physical layer. In order to support beam-based transmission on the NR frequency band, it may be periodically transmitted based on a set of one or more block indices. The synchronization signal is composed of a Primary Sidelink Synchronization Signal (PSSS) and a Secondary Sidelink Synchronization Signal (SSSS), and a sequence for the corresponding signal may be generated based on at least one SLSS ID value. PSBCH is transmitted together with SLSS for the purpose of delivering system information required to perform V2X SL communication, and is periodically transmitted in the form of a set of SLSS/PSBCH block indices to support beam-based transmission.

3 is a diagram illustrating an NR sidelink slot structure to which the present disclosure can be applied.

As shown in FIG. 3 , one sidelink slot (SL slot) includes one automatic gain control (AGC) symbol and one transmit-receive switching (Tx-Rx switching) symbol, respectively. At least one subchannel of one or more subchannels through which the PSSCH is transmitted and the remaining OFDM symbols are configured with PSCCH (1st SCI), 2nd SCI, and PSSCH (Data) and DMRS (Demodulation Reference Signal) for demodulation as shown in FIG. 3 and location and can be transmitted. For the PSSCH subchannel in which the PSCCH and the 2nd SCI do not exist, the PSSCH and the DMRS may be allocated and transmitted as shown in the figure.

One or more ports of PSSCH DMRS may be configured according to the channel environment of the terminal according to the upper layer configuration. 2nd SCI is decoded using PSSCH DMRS. On the other hand, the PSCCH (1st SCI) is decoded and received using the DMRS of the PSCCH (ie, the PSCCH DMRS), and the DMRS of the PSCCH is equally allocated to every 4 REs in one RB and transmitted.

4 is a diagram illustrating an NR sidelink frequency to which the present disclosure can be applied.

NR sidelink is basically the frequency range (Frequency Range) FR1 and FR2 (ie, up to 52.6 GHz), the unlicensed ITS (Intelligent Transport System) band (unlicensed ITS bands) and licensed band (licensed band) can be considered. A frequency band of 5,855-5,925 MHz may be allocated and utilized as shown in FIG. 4 for an ITS service (technology neutral manner). A common design method to support the corresponding frequency band is preferred.

Hereinafter, NR V2X QoS requirements will be described.

For NR V2X, strict and various QoS requirements may be applied compared to LTE V2X. For example, for NR V2X, a shorter delay, higher reliability, and higher data rate QoS may be required compared to LTE V2X.

In order to satisfy these QoS requirements, access stratum (AS) level QoS management is required, and HARQ and CSI related to link adaptation are required. In addition, the maximum bandwidth capability (capability) of each NR V2X UE may be different. Accordingly, AS level information including UE capability, QoS related information, radio bearer configuration, physical layer configuration, etc. will be exchanged between terminals. There is a need.

Table 5 below includes an example of QoS requirements for SL NR V2X on PC5 link (or sidelink). In Table 5, PQI is defined as an indicator for PC5 QoS characteristics.

PQI
Value Resource Type Default Priority Level Packet Delay Budget Packet Error
Rate Default Maximum Data Burst Volume
Default
Averaging Window Example Services One
GBR 3 20 ms
10 ^-4 N/A 2000 ms Platooning between UEs - Higher degree of automation;
Platooning between UE and RSU - Higher degree of automation; 2
4 50 ms 10 ^-2 N/A 2000 ms Sensor sharing - higher degree of automation 3 3 100 ms 10 ^-4 N/A 2000 ms Information sharing for automated driving - between UEs or UE and RSU - higher degree of automation; 55 Non-GBR 3 10 ms 10 ^-4 N/A N/A cooperative lane change - higher degree of automation; 56 6 20 ms 10 ^-1 N/A N/A Platooning informative exchange - low degree of automation;
Platooning - information sharing with RSU; 57 5 25 ms 10 ^-1 N/A N/A Cooperative lane change - lower degree of automation; 58 4 100 ms 10 ^-2 N/A N/A Sensor information sharing - lower degree of automation 59 6 500 ms 10 ^-1 N/A N/A Platooning - reporting to an RSU; 82 Delay Critical GBR 3 10 ms
10 ^-4 2000 bytes 2000 ms cooperative collision avoidance;
Sensor sharing - Higher degree of automation;
Video sharing - higher degree of automation; 83 2 3 ms 10 ^-5 2000 bytes 2000 ms Emergency trajectory alignment;
Sensor sharing - Higher degree of automation

The mapping relationship between PQI and QoS characteristics as shown in Table 5 is only exemplary, and items not included in Table 5 may be added or some contents may be modified in order to satisfy service requirements for other V2X services. In the present disclosure, rather than using the predefined mapping relationship between PQI and QoS characteristics as described above, QoS characteristic items defined for the PC5 sidelink (eg, packet delay budget (PDB), packet error rate (PER), etc.) ) is considered to be used.

Hereinafter, the sidelink HARQ procedure will be described.

The HARQ feedback may include ACK/NACK information indicating whether the UE has succeeded in decoding the received data.

In sidelink HARQ feedback, whether to report HARQ feedback information may be set to enable/disable by a higher layer (eg, a Radio Resource Control (RRC) layer). In the case of groupcast, even when HARQ feedback reporting is activated, whether to perform HARQ reporting may be determined according to the Tx-Rx distance.

When SL HARQ feedback is activated for unicast, the receiving terminal (Rx UE) may generate HARQ-ACK/NACK according to whether the corresponding transport block (TB) is successfully decoded.

When SL HARQ feedback is activated for groupcast, two options may be supported. Option 1 is that the receiving terminal transmits only HARQ NACK. Option 2 is that the receiving terminal transmits HARQ ACK or NACK (ACK/NACK). In the case of option 1, the transmitting terminal cannot clearly determine whether the data has been successfully decoded at the receiving terminal or whether the data has not reached the receiving terminal without HARQ feedback from the receiving terminal, but there is an overload for HARQ feedback transmission has the advantage of being reduced.

The following may be applied to SL HARQ feedback activation/deactivation in unicast and groupcast.

- For example, it may be determined according to the channel state (eg, RSRP (Reference Signal Receiving Power)), Tx-Rx distance, QoS requirements, etc.

- In the case of groupcast, transmission of HARQ-feedback may be determined according to at least Tx-Rx geographic distance (in addition, L1-RSRP may be considered)

- At least for option 1 of the Tx-Rx distance-based HARQ feedback scheme for groupcast,

-- If the Tx-Rx distance is less than or equal to the communication range requirement, the UE transmits the HARQ feedback for the PSSCH, otherwise the UE does not transmit the HARQ feedback for the PSSCH

--- The location of the transmitting terminal (Tx UE) may be indicated by the SCI associated with the PSSCH

--- The receiving terminal (Rx UE) can estimate the Tx-Rx distance based on its own location and the location of the transmitting UE

Hereinafter, embodiments of the present disclosure for NR V2X frequency resource selection or reselection scheme will be described.

The present disclosure describes embodiments related to an NR SL design that satisfies new requirements for advanced V2X (eV2X) services. In addition, embodiments of the present disclosure may be applied to other NR SL-based services, for example, NR SL design for public safety, wearable, and the like.

In addition, the NR SL frequency for NR SL operation in the present disclosure may exist within FR1 (410 MHz to 7.125 GHz) and FR2 (24.25 GHz to 52.6 GHz), and includes unlicensed bands and licensed bands. Assume an NR SL design considering both the ITS band and the frequency band and range in which the NR system operates. It is also assumed that a common design should be applicable in both FR1 and FR2. In addition, the availability of the LTE (ng-eNB) / NR (gNB) Uu link, which is a 3GPP NG-RAN network (in particular, the related configuration for SL data transmission and reception and the purpose of SL physical resource allocation) can be considered for NR SL V2X transmission and reception procedures. have.

Existing NR SL supports operating on only one carrier and/or SL bandwidth portion (BWP). However, in the present disclosure, in order to support a higher data rate and provide flexibility in connection diversity and frequency spectrum use, NR SL data on one or more carriers/SL BWPs instead of one carrier/BWP as in the conventional method. A technology that supports transmission and reception will be described. More specifically, when one or more SL carriers/BWPs are configured or provided to an NR SL terminal, a method of selecting or reselecting a carrier/BWP for NR SL data transmission among them is proposed through the present disclosure.

First, a transmission carrier (Tx carrier) selection procedure in LTE V2X will be described.

The MAC entity may consider the Channel Busy Ratio (CBR) of one carrier. For example, if the physical (PHY) layer provides the CBR measurement result to the MAC entity, the MAC entity may consider the corresponding CBR measurement value. Otherwise (ie, when the CBR measurement result is not provided from the PHY), the MAC entity may consider a default value (eg, defaultTxConfigIndex) set by a higher layer (eg, RRC).

If transmission carrier selection or reselection is triggered for one SL process, the MAC entity may operate as follows.

- If there is no SL grant configured for any carrier for an SL logical channel (LC) in which data exists, the CBR of a certain carrier is a threshold value associated with the priority of the SL LC (eg, threshCBR-FreqReselection), the corresponding carrier may be considered as a candidate carrier for Tx carrier selection for the corresponding SL LC. Here, the mapping relationship between the SL LC and its associated carrier may be indicated by the RRC.

- Otherwise (that is, if there is an SL grant configured for a carrier for an SL LC in which data exists), the following operation may be performed for each SL LC (or a carrier associated with the corresponding SL LC).

-- If the CBR of the corresponding carrier is smaller than a threshold value (eg, threshCBR-FreqKeeping) associated with the priority of the SL LC, a resource pool associated with the corresponding carrier may be selected for the corresponding SL LC.

-- Otherwise (that is, if the CBR of the corresponding carrier is greater than or equal to a threshold associated with the priority of the SL LC (eg, threshCBR-FreqKeeping)), for each carrier, the CBR of the corresponding carrier is the priority of the SL LC If it is smaller than the threshold associated with (eg, threshCBR-FreqReselection), the corresponding carrier may be considered as a candidate carrier for Tx carrier selection for the corresponding SL LC.

When there are a plurality of candidate carriers considered according to the above procedure, the MAC entity may list the candidate carriers in ascending order from the lowest CBR value for each SL LC, and may select one or a plurality of carriers from among them.

In LTE V2X as described above, the carrier configuration associated with one SL LC, the CBR value measured in the physical layer for each carrier, and the QoS value for the SL LC (eg, PPPP (ProSe Per-Packet Priority)) In this LTE V2X, standardization was made around the purpose of delivering a basic safety message based on broadcast transmission and its related requirements, whereas NR V2X is covered in LTE V2X technology. It is being introduced as a new radio access technology that can satisfy more diverse and evolved service scenarios and higher QoS requirements that cannot be achieved.

In addition, in NR V2X, in addition to the FR1 band including the ITS carrier that LTE V2X can be utilized, SL data transmission on the FR2 band including the millimeter wave (mmWave) band may be considered. In addition, in NR SL, a new unit of frequency resource called a bandwidth portion (BWP) may be set in consideration of radio frequency capability (RF capability) of the terminal. However, the method of selecting a frequency resource based on the QoS required on LTE V2X (ie, the CBR reference method), it is difficult to sufficiently meet the new NR V2X scenario and service requirements and the operating environment. Therefore, a new Tx carrier/BWP (re-)selection scheme is required for the NR SL operating environment.

Hereinafter, specific embodiments for the NR V2X transmitting terminal to select a transmission frequency resource will be described.

The following embodiments are described assuming that frequency resource selection for NR V2X communication is frequency resource selection on NR SL, but the scope of the present disclosure is not limited to these embodiments, and direct link communication in any manner Therefore, embodiments of the present disclosure may be applied for frequency resource selection on a direct link.

In addition, the following embodiments will be described assuming a Tx carrier and/or BWP as NR SL frequency resources, but the scope of the present disclosure is not limited to these embodiments, and a frequency resource defined in an arbitrary unit may be selected. For this, embodiments of the present disclosure may be applied.

In addition, the following embodiments are mainly described on the assumption that operation according to the terminal autonomous resource selection mode, but the scope of the present disclosure is not limited to these embodiments, and also for the terminal operating according to the base station resource scheduling mode Embodiments of the present disclosure may be applied.

In addition, the following embodiments are applicable even when a frequency resource is selected in a situation where there is no previously configured frequency resource for the terminal, and even when there is a previously configured frequency resource for the terminal but newly reselecting a frequency resource Applicable.

In addition, the following embodiments mainly describe a procedure for the terminal to determine a candidate for a frequency resource, and one or a plurality of frequency resources may be finally selected from among the determined candidate for a frequency resource.

5 is a flowchart for explaining an example of a frequency resource selection method to which the present disclosure can be applied.

In step S510, an available carrier may be configured for the transmitting terminal, and a frequency resource associated with or mapped to the SL LC may be configured. For example, available carriers and SL LC mapping frequency resources may be configured for the MAC entity of the transmitting terminal.

The available carriers may be configured as one or more transmit carriers and/or one or more receive carriers that the corresponding transmitting terminal can use on the NR SL.

The frequency resource mapped to the SL LC may correspond to, for example, a transport carrier and/or BWP allowed for transmission for one SL LC.

The configuration of available carriers and SL LC mapping frequency resources may be explicitly or implicitly provided from the base station to the transmitting terminal by higher layer (eg, RRC) signaling, or transmitted without separate signaling according to a predetermined setting. The terminal may decide.

All of the available carrier and SL LC mapping frequency resources set in this way are not always selected as NR SL frequency resources of the transmitting terminal, and after determining all or part of them as frequency resource candidates, one or more frequency resource candidates from among the determined frequency resource candidates can be finally selected.

In step S520, frequency resource selection or reselection may be triggered for the transmitting terminal.

Frequency resource selection or reselection may be triggered for one sidelink process (SL process).

A condition for triggering frequency resource selection or reselection may be defined as follows.

- If there is no SL grant (configured SL grant) configured on any frequency resource (eg, carrier and/or BWP) in which SL data transmission is permitted, or

- When the resource pool in which the SL grant is set is reset by the upper layer, or

- One MAC entity is configured to perform SL data transmission in one or a plurality of resource pools by the upper layer, and the corresponding MAC entity selects to generate one configured SL grant for one MAC PDU transmission, STCH When data transmission is on one or multiple carriers within (Sidelink Traffic Channel)

In addition to the above-described example, frequency resource selection or reselection may be triggered by other methods. For example, when it is determined that a frequency resource currently being transmitted or scheduled to be transmitted cannot satisfy QoS required for data being transmitted or scheduled to be transmitted, or a transmission failure is detected above a predetermined threshold. In some cases, frequency resource selection or reselection may be triggered.

When frequency resource selection or reselection is triggered in this way, the MAC entity may determine a frequency resource candidate.

In step S530, a frequency resource candidate may be determined based on predetermined information.

For example, the MAC entity of the transmitting terminal may determine a frequency resource candidate, and for this purpose, information obtained from a lower layer (eg, PHY) and/or an upper layer (eg, application layer, RRC layer, etc.) can be used

Information used for frequency resource candidate determination may be defined as a metric or parameter indicating characteristics of each frequency resource. For example, a carrier and/or a BWP candidate may be determined based on information indicating a characteristic of a specific carrier or a specific carrier group, information indicating a characteristic of a specific BWP or a specific BWP group, and the like.

Information used for frequency resource candidate determination may indicate one or more different characteristics. When information on a plurality of characteristics is provided, a frequency resource candidate may be determined based on a combination thereof.

Information indicating the characteristics of the frequency resource may be compared with a predetermined threshold to determine the frequency resource as a candidate. For example, a threshold value for a predetermined characteristic related to SL LC may be preset, and a corresponding frequency resource is selected according to whether a value of a metric or parameter for a corresponding characteristic of a frequency resource satisfies the threshold value. can also be determined as In addition, a threshold value for a predetermined characteristic of a frequency resource may be preset, and a corresponding frequency resource may be determined as a candidate according to whether a metric or parameter value for a corresponding characteristic related to SL LC satisfies the threshold value. .

This threshold value may be determined by the terminal without separate signaling according to a predetermined setting, or may be set to the terminal through higher layer signaling. In addition, such a threshold value may be set in relation to the priority (eg, PQI) of the SL LC.

In order to determine a frequency resource candidate, various aspects of information may be considered. NR SL must support carriers in FR1 as well as FR2 frequency range and BWPs within those carriers. Therefore, various aspects of frequency characteristics (eg high signal attenuation, sensitive signal distortion (eg phase noise), etc.) for carriers/BWPs in the FR2 frequency range must be considered.

For example, information used for frequency resource candidate determination may be defined for one or more of frequency resource congestion, geographic factor, link quality, or feedback information.

The frequency resource congestion level may be determined based on an occupancy time, a detected energy level, a detected signature signal, and the like. For example, the frequency resource congestion may be expressed as a Channel Busy Ratio (CBR).

Geographic factors include the communication range supported by the frequency resource, the geographical location of the transmitting terminal or the receiving terminal using the frequency resource, the distance between the transmitting terminal and the receiving terminal, the absolute or relative movement speed of the transmitting terminal or the receiving terminal, the transmitting terminal or the receiving terminal It may include a geographic area to which it belongs, a geographic range formed by a cluster including a plurality of terminals, and the like.

Link quality includes delay (eg, PDB), error rate (eg, PER), interference, signal strength (eg, RSRP, RSSI), signal quality (eg, RSRQ) supported by a frequency resource. and the like.

The feedback information is information transmitted from the receiving terminal to the transmitting terminal, and may include HARQ feedback information, CSI information, and the like. In addition, information on a geographic element of the receiving terminal (eg, location, speed, area, etc. of the receiving terminal) may be included in the feedback information or may be transmitted to the transmitting terminal in a manner distinct from the feedback information.

In step S540, a frequency resource may be selected from frequency resource candidates.

For example, the MAC entity of the transmitting terminal may select one or a plurality of frequency resources from the frequency resource candidates determined in step S530.

As a specific example, one or more high-order frequency resources may be selected from among the candidates listed in ascending or descending order of the parameter values used for candidate determination among the determined frequency resource candidates.

In addition, one or a plurality of frequency resources satisfying the terminal capability may be finally selected from among the determined frequency resource candidates. For example, the capability of the terminal may include the number of frequency resources simultaneously supported by the terminal, the RF capability supported by the terminal, the frequency range supported by the terminal, and the like.

In step S550, the transmitting terminal may transmit data belonging to the SL LC on the selected frequency resource.

For example, the MAC entity of the transmitting terminal may deliver information indicating the selected frequency resource to the lower layer. A lower layer (eg, PHY) may map a channel and/or a signal on a frequency resource indicated by a higher layer and transmit it to a receiving terminal.

Hereinafter, an example of using the first parameter, the second parameter, or the third parameter as information for determining a frequency resource candidate will be described. Of course, examples of using only one parameter or using three or more parameters are not excluded, and examples related to priorities related to application of a plurality of parameters will be described later.

When the first parameter is used, a frequency resource candidate may be determined by comparing a characteristic value related to a specific frequency resource and a threshold value related to a priority (eg, PQI) of a specific SL LC.

For example, when the MAC entity receives the value of the first parameter for the frequency resource from the lower layer or the upper layer, the MAC entity may determine a frequency resource candidate by using it. Otherwise (that is, when the value of the first parameter is not transmitted), the MAC entity may determine a frequency resource candidate by applying a preset default value to the value of the first parameter.

If frequency resource selection is triggered for one SL process, the MAC entity may operate as follows.

- If there is no SL grant configured for any frequency resource mapped to the SL LC in which data exists, the first parameter value of any frequency resource is the first threshold value for the first parameter associated with the priority of the corresponding SL LC If it is less than / less than (or more than / more than), the corresponding frequency resource may be determined as a candidate.

- Otherwise (that is, if there is an SL grant configured for a frequency resource mapped to an SL LC in which data exists), the following operation is performed for the corresponding SL LC (or the frequency resource mapped to the corresponding SL LC). can

-- If the value of the first parameter of the corresponding frequency resource is less than / less than (or more than / greater than) the second threshold value for the first parameter associated with the priority of the SL LC, the frequency resource mapped to the SL LC is used as a candidate can decide

-- Otherwise (that is, if the value of the first parameter of the corresponding frequency resource is greater than / greater than (or less than / less than) the second threshold value for the first parameter associated with the priority of the SL LC), the corresponding frequency resource If the first parameter value of is less than / less than (or greater than / greater than) the first threshold value for the first parameter associated with the priority of the corresponding SL LC, the corresponding frequency resource may be determined as a candidate.

As an additional example, when the second parameter is used, a frequency resource candidate may be determined by comparing a characteristic value related to a priority (eg, PQI) of a specific SL LC with a threshold value related to a specific frequency resource.

For example, when the MAC entity receives the value of the second parameter related to the priority of the SL LC from the higher layer, the MAC entity may determine a frequency resource candidate by using it. Otherwise (that is, when the value of the second parameter is not transmitted), the MAC entity may determine a frequency resource candidate by applying a preset default value to the value of the second parameter.

If frequency resource selection is triggered for one SL process, the MAC entity may operate as follows.

- If there is no SL grant configured for any frequency resource mapped to the SL LC in which data exists, the second parameter value associated with the priority of the corresponding SL LC is the first threshold for the second parameter value of any frequency resource If it is less than / less than (or more than / more than) the value, the corresponding frequency resource may be determined as a candidate.

- Otherwise (that is, if there is an SL grant configured for a frequency resource mapped to an SL LC in which data exists), the following operation is performed for the corresponding SL LC (or the frequency resource mapped to the corresponding SL LC). can

-- If the value of the second parameter related to the priority of the corresponding SL LC is less than / less than (or more than / greater than) the second threshold value for the second parameter of the corresponding frequency resource, the frequency resource mapped to the corresponding SL LC is a candidate can be determined as

-- Otherwise (that is, if the value of the second parameter associated with the priority of the corresponding SL LC is greater than / greater than (or less than / less than) the second threshold value for the second parameter of the corresponding frequency resource), the corresponding SL If the second parameter value associated with the priority of the LC is less than/below (or more than/exceeded from) the first threshold value for the second parameter value of the corresponding frequency resource, the corresponding frequency resource may be determined as a candidate.

As an additional example, when using the third parameter, a characteristic value that is not associated with a specific frequency resource (or common to all frequency resources, or terminal-specific) and a priority (eg, PQI) of a specific SL LC are associated A frequency resource candidate may be determined by comparing the threshold values.

For example, when the value of the third parameter associated with all frequency resources is received from a lower layer or a higher layer, the MAC entity may determine a frequency resource candidate by using it. Otherwise (ie, when the value of the third parameter is not transmitted), the MAC entity may determine a frequency resource candidate by applying a preset default value to the value of the third parameter.

If frequency resource selection is triggered for one SL process, the MAC entity may operate as follows.

- If there is no SL grant configured for any frequency resource mapped to the SL LC in which data exists, the third parameter value of any frequency resource is the first threshold value for the third parameter associated with the priority of the corresponding SL LC If less than / less than (or more than / greater than), the frequency resource may be determined as a candidate.

- Otherwise (that is, if there is an SL grant configured for a frequency resource mapped to an SL LC in which data exists), the following operation is performed for the corresponding SL LC (or the frequency resource mapped to the corresponding SL LC). can

-- If the value of the third parameter of the corresponding frequency resource is less than / less than (or more than / greater than) the second threshold value for the third parameter associated with the priority of the SL LC, the frequency resource mapped to the SL LC is used as a candidate can decide

-- Otherwise (that is, if the value of the third parameter of the corresponding frequency resource is greater than / greater than (or less than / less than) the second threshold value for the third parameter associated with the priority of the SL LC), the corresponding frequency resource If the third parameter value of is less than/less than (or more than/exceeding) the first threshold value for the third parameter associated with the priority of the corresponding SL LC, the corresponding frequency resource may be determined as a candidate.

In the above example, when all of the condition for the first parameter, the condition for the second parameter, and the condition for the third parameter are satisfied, the corresponding frequency resource may be determined as a candidate. However, the present disclosure is not limited to this example, and a frequency resource satisfying one or more of the first to third parameters may be determined as a candidate.

Hereinafter, specific examples of information used to determine frequency resource candidates will be described.

CBR

By comparing the CBR measurement value of the frequency resource mapped with one SL LC and the CBR threshold associated with the priority (eg, PQI) of the SL LC, the frequency resource having a CBR measurement value less than / below the threshold is Candidates can be determined. Otherwise, the corresponding frequency resource may not be considered as a candidate.

Here, the CBR measurement value of the frequency resource may be provided from the physical layer. In addition, the CBR threshold may be defined as a CBR threshold for frequency resource (re)selection.

communication range

By comparing the communication range value associated with the priority of one SL LC and the communication range threshold value for the frequency resource mapped to the corresponding SL LC, a frequency resource having a communication range value less than / less than the threshold value may be determined as a candidate. . Otherwise, the corresponding frequency resource may not be considered as a candidate.

Here, the communication range value related to the priority of the SL LC may be defined as a communication range requirement value related to the priority (eg, PQI) of the corresponding SL LC. In addition, the communication range threshold may be defined as a threshold allowed or set to be transmittable for each frequency resource mapped to the SL LC or for each frequency range (eg, FR1 or FR2) in which the frequency resource is located.

For example, the communication range value associated with the priority (PQI) of the SL LC among the transmission carriers/BWPs allowed to transmit one SL LC is for each carrier/BWP or the frequency range in which the carrier/BWP is located ( For example, if it is smaller than the communication range threshold allowed per FR1 or FR2), the corresponding carrier/BWP may be considered as a candidate transmission carrier/BWP. Otherwise, the carrier/BWP is not considered as a candidate transmission carrier/BWP.

The communication range requirement for SL data communication may be given as one of {50, 80, 180, 200, 350, 400, 500, 700, 1000 meters}, and this communication range requirement value is SL LC may be associated with a PQI value of . That is, a supportable communication range value may be determined according to a PQI value that is a priority value of the SL LC.

A communication range threshold for a frequency resource or a frequency range to which a frequency resource belongs may be set by higher layer signaling or a predetermined value may be applied for each frequency range (eg, FR1 or FR2).

In NR SL, a communication range is defined as one piece of QoS information. In addition, communication range information associated with one SL data transmission may be utilized in the radio access layer. For example, the communication range value may be used as one threshold value in determining whether the terminal receiving the PSSCH in the physical layer performs HARQ feedback transmission. More specifically, when the SL transmission/reception terminal is configured to perform PSSCH data transmission based on SL HARQ feedback, control information for PSSCH transmission is provided to the reception terminal through SCI by the transmitting terminal, and accordingly, SL data transmission through the PSSCH This can be done. In this case, in order to help the receiving terminal determine whether to transmit the SL HARQ feedback, a communication range value may be included in the SCI information and transmitted. Receiving the communication range value, the receiving terminal may determine whether to transmit the SL HARQ feedback by comparing the information obtained by calculating the transmission-receiving distance with the provided communication range value. In this embodiment, the threshold value for such a communication range may be used for SL frequency resource candidate selection.

In general, since frequency characteristics on a frequency resource belonging to a low frequency range (eg, FR1) have characteristics of low signal attenuation and low signal distortion, a high frequency range (eg, FR2) under the same conditions such as transmission power It can provide a wider communication range compared to the frequency resources belonging to Therefore, by comparing the communication range requirement value associated with the priority (eg, PQI) of the SL LC and the communication range threshold value of the frequency resource associated with the SL LC, an appropriate frequency resource (re)selection operation is performed. can Here, the communication range threshold of each frequency resource may be set in a higher layer or used as a predetermined value for the frequency range.

Tx-Rx Distance

The transmit-receive distance may be applied as an example of a communication range threshold.

For example, by comparing the communication range value related to the priority of one SL LC and the transmit-receive distance for the frequency resource mapped to the corresponding SL LC, the frequency resource having a communication range value that is less than / less than the transmit-receive distance This can be determined as a candidate. Otherwise, the corresponding frequency resource may not be considered as a candidate.

Here, the communication range value related to the priority of the SL LC may be defined as a communication range requirement value related to the priority (eg, PQI) of the corresponding SL LC. In addition, the transmit-receive distance may be defined as a value calculated for each frequency resource mapped to the SL LC or for each frequency range (eg, FR1 or FR2) in which the frequency resource is located.

For example, among the transmission carriers / BWPs mapped to one SL LC, the communication range value associated with the priority (eg, PQI) of the corresponding SL LC is for each transmission carrier / BWP or the transmission carrier / BWP is If it is smaller than the transmit-receive distance value calculated for each located frequency range (eg, FR1 or FR2), the corresponding transmit carrier/BWP may be considered as a candidate transmit carrier/BWP. Otherwise, the corresponding transmission carrier/BWP may not be considered as a candidate transmission carrier/BWP.

The transmit-receive distance information may be calculated from an SL signal (eg, SCI) transmitted from the transmitting terminal to the receiving terminal. If the transmit-receive distance information is available, the transmit-receive distance may be used by replacing the communication range threshold in the method of determining a frequency resource candidate using the communication range. However, a method of determining a frequency resource candidate using the transmit-receive distance may not always be available.

For example, when data is transmitted from the first terminal (transmitting terminal) to the second terminal (receiving terminal), it is assumed that data or other SL signals are transmitted from the second terminal to the first terminal before that. can do. In this case, the first terminal may calculate the distance between the two terminals based on the SL signal previously received from the second terminal. If the first terminal has not previously received the SL signal from the second terminal, the first terminal may not be able to calculate the distance between the two terminals. That is, reception of the signal from the second terminal (receiving terminal) in the first terminal (transmitting terminal) must occur first so that the transmission-receiving distance can be determined in the first terminal (transmitting terminal). Therefore, the first terminal ( When the transmitting terminal) performs data transmission to the second terminal (receiving terminal), the transmit-receive distance may not be determined. Therefore, in determining the frequency resource candidate, the communication range value is used preferentially or as a default, and if the transmit-receive distance is available, a method of using the transmit-receive distance instead of the communication range threshold may be applied. .

As a further example, the transmit-receive distance may be applied as one example of a communication range value.

For example, using the communication range requirement value associated with the priority of one SL LC as a threshold value, and comparing the transmit-receive distance for the frequency resource mapped to the SL LC with the communication range requirement value, A frequency resource having a transmit-receive value that is less than/below the range requirement may be determined as a candidate.

Sending terminal speed

By comparing the speed of the transmitting terminal and the speed threshold associated with the priority (eg, PQI) of one SL LC, when the speed of the transmitting terminal is less than/below the threshold, it is mapped to the SL LC frequency resource may be determined as a candidate. Otherwise, the corresponding frequency resource may not be considered as a candidate.

The speed threshold may be set through an upper layer. The speed of the terminal may be determined by the terminal itself.

For example, if the speed threshold associated with the priority (eg, PQI) of the SL LC is set by the upper layer to 100 km/h, and the current speed of the terminal is 80 km/h (ie, less than the threshold) , all transmit carriers/BWPs corresponding to the FR1 and FR2 frequency ranges may be considered as candidate transmit carriers/BWPs. Otherwise (that is, when the speed of the current terminal exceeds the threshold of 100 km/h), it may be determined that there is no candidate transmission carrier/BWP.

Alternatively, when the speed of the terminal is less than/below the threshold, a frequency resource belonging to a specific frequency range (eg, FR1), a first frequency resource set, or a frequency resource belonging to an ITS band (or an unlicensed band) is a candidate frequency resource can be determined as When the speed of the terminal is equal to or greater than the threshold value, a frequency resource belonging to a specific frequency range (eg, FR2), a second frequency resource set, or a frequency resource belonging to a licensed band may be determined as a candidate frequency resource.

Packet Delay Budget (PDB)

By comparing the PDB value associated with the priority (eg, PQI) of one SL LC and the delay threshold value of the frequency resource mapped to the corresponding SL LC, a frequency resource satisfying the delay requirement may be determined as a candidate. . Otherwise, the corresponding frequency resource may not be considered as a candidate.

Here, the delay threshold of the frequency resource may be set by a higher layer. In addition, the delay threshold may be set for each frequency resource, may be set for each frequency range, or may be set to be terminal-specific.

For example, when the PDB value associated with the PQI of the SL LC is equal to or greater than the delay threshold, it is possible to support a lower delay value among frequency resources mapped to the SL LC (eg, supporting high subcarrier spacing). ) frequency resource may be determined as a candidate.

Alternatively, when the PDB value associated with the PQI of the SL LC is less than/below the delay threshold, a frequency resource capable of supporting a higher delay value among frequency resources mapped to the SL LC (eg, supporting high subcarrier spacing) This can be determined as a candidate.

feedback information

The feedback information corresponds to control information transmitted from the receiving terminal to the transmitting terminal in the physical layer. For example, the first layer (or physical layer) feedback information may include HARQ feedback information, CSI (RI, CQI, etc.), zone identifier (Zone ID) information, and the like.

Frequency having a value related to feedback information that is less than/below the threshold value by comparing a value related to feedback information of a frequency resource mapped to one SL LC with a threshold value related to a priority (eg, PQI) of the corresponding SL LC A resource may be determined as a candidate. Otherwise, the corresponding frequency resource may not be considered as a candidate.

For example, the number of HARQ NACKs or ACKs fed back during a predetermined period for each frequency resource associated with the SL LC may be counted. In addition, a threshold value related to the number of NACK or ACK counts related to the priority (eg, PQI) value of the SL LC may be set. In this case, when the number of NACK counts of a certain frequency resource is less than/below the NACK count number threshold, the corresponding frequency resource may be determined as a candidate. Alternatively, when the number of ACK counts of a certain frequency resource is equal to or greater than/exceeding the ACK count threshold value, the frequency resource may be determined as a candidate. Alternatively, when the ratio of the number of NACK counts to the number of ACK counts of a frequency resource is less than / less than (or more than / more than) a threshold related to the ratio of the number of NACK counts and the number of ACK counts, the frequency resource can be determined as a candidate. have.

Here, the predetermined period may be referred to as an ACK/NACK count time period. The size of the ACK/NACK count time interval and/or the position in the time domain may be set by a higher layer or a predetermined value may be used. Alternatively, the ACK/NACK count period may be defined as the number of times the transmitting terminal transmits SL data (or PSSCH) to the receiving terminal, instead of being defined as a continuous time period.

As a further example, the averaged or arbitrarily determined CQI value fed back for a specific time period for each frequency resource associated with the SL LC is compared with the CQI threshold value associated with the priority (eg, PQI) value of the SL LC, the threshold A frequency resource having a CQI value that is less than / less than (or greater than / more than) a value may be determined as a candidate.

As such, the feedback information has a relatively short duration compared to the CBR measurement value, which is long-term metric information on the channel occupancy status of frequency resources in the physical layer in unicast or groupcast-based SL data transmission. It corresponds to (short-term) metric information. Accordingly, when a frequency resource candidate is determined using the feedback information, the characteristics of the frequency resource may be dynamically reflected.

Specifically, since measuring the channel occupancy of the frequency resource by the CBR measurement value directly performed by the transmitting terminal only considers the long-term channel state information, short-period channel state information experienced by the receiving terminal on the corresponding frequency resource (eg, interference level, hidden node problem, etc.) cannot be considered for transmission frequency resource selection of data transmission of SL LC. In addition, compared to LTE V2X that supports only periodic traffic, NR SL should be designed in consideration of both periodic and aperiodic traffic. Therefore, it is necessary to select a transmission frequency resource in consideration of aperiodic traffic. Therefore, in order to overcome the limitation of not supporting the above NR SL characteristic when the transmitting terminal selects a transmission frequency resource using only the CBR value measured by the transmitting terminal, at least L1 feedback information available in the case of unicast or groupcast is transmitted to the transmitting terminal. This may be used to select a transmission frequency resource or determine a candidate. Since such feedback information better reflects the channel environment actually experienced by the receiving terminal, the reliability of data transmission in the SL LC can be greatly improved.

Hereinafter, priority or application criteria among parameters used for determining frequency resource candidates will be described.

The MAC entity of the transmitting terminal may determine a transmittable candidate frequency resource by combining one of the above-described parameters or methods for a plurality of parameters among a plurality of frequency resources configured for data transmission on one SL LC. If a frequency resource candidate is determined, priorities between a plurality of parameters may be determined in the following manner. The following prioritization method is only one example, and priorities between parameters described in the present disclosure may be set in various ways, and a candidate frequency resource may be determined based thereon.

If the candidate frequency resources are determined based on a plurality of parameters, the candidate frequency resources may be arranged in ascending or descending order based on a condition for at least one parameter among the plurality of parameters.

For example, when a candidate frequency resource is determined using the condition for the first parameter and the second condition for the second parameter, one or more frequency resource candidates satisfying both the condition for the first parameter and the second parameter exist. can In this case, the one or more frequency resource candidates may be sorted based on the condition for the first parameter. Here, the condition for the second parameter may not be used for candidate alignment. Among the sorted frequency resource candidates, the top n (n is an integer greater than or equal to 0) frequency resources may be selected according to UE capabilities.

For example, if the condition for the CBR parameter and the condition for the communication range parameter are used, one or more frequency resource candidates satisfying both the CBR parameter condition and the communication range parameter condition may be determined. The one or more frequency resource candidates may be arranged in descending order in the order of having a low CBR value. Here, the communication range parameter condition is not used for sorting in descending order. Thereafter, from among the candidates arranged in consideration of the RF capability of the terminal, a frequency resource capable of transmitting as much as the capability of the terminal may be finally selected in the order of having a low CBR. Here, the number n of frequency resources that are finally selected may be determined according to the implementation and capability of the terminal.

As an additional example, if the condition for the CBR parameter and the condition for the PDB parameter are used, one or more frequency resource candidates satisfying both the CBR parameter condition and the PDB parameter condition may be determined. The one or more frequency resource candidates may be arranged in descending order in the order of having a low CBR value. Here, the PDB parameter condition is not used for sorting in descending order. Thereafter, from among the candidates arranged in consideration of the RF capability of the terminal, a frequency resource capable of transmitting as much as the capability of the terminal may be finally selected in the order of having a low CBR. Here, the number n of frequency resources that are finally selected may be determined according to the terminal implementation and capabilities.

As an additional example, a first set of frequency resources in which priorities between a plurality of parameters are preset, satisfy a condition for a relatively high-priority parameter, and a frequency that satisfies a condition for a relatively low-priority parameter The second set of resources may be determined separately. In this case, after arranging frequency resource candidates in the order of frequency resources belonging to both the first and second sets, frequency resources belonging to only the first set, and frequency resources belonging only to the second set, the top n frequency resource candidates are selected from among the sorted frequency resource candidates. A frequency resource may be selected according to terminal capability.

As an additional example, when the condition for the first parameter has a higher priority than the condition for the second parameter, a temporary candidate of the frequency resource is determined based on the first parameter condition, and for the temporary candidate, the second parameter condition is based A method of determining a candidate frequency resource may be applied. From among the determined candidate frequency resources, a possible number (n) of frequency resources may be finally selected according to the capability of the terminal.

Application conditions for various parameters used for frequency resource candidate determination described in the present disclosure may be set.

For example, the frequency resource candidate determination method based on the communication range parameter may be applied to SL LC corresponding to groupcast transmission, but may not be applied to broadcast or unicast transmission. Alternatively, the frequency resource candidate determination method based on the feedback information parameter may be applied to SL LC corresponding to unicast or groupcast transmission, but may not be applied to broadcast transmission. Alternatively, a method of determining a frequency resource candidate based on a CBR parameter may be applied regardless of a cast method.

6 is a flowchart for explaining an additional example of a frequency resource selection method to which the present disclosure can be applied.

6 illustrates a procedure for finally selecting an SL transmission frequency resource from among a plurality of transmission frequency resources in which one MAC entity is configured, based on QoS information of the SL LC, its determination conditions, and related settings.

In step S610, the MAC entity of the terminal may trigger the SL transmission frequency resource selection procedure when the triggering condition for the SL transmission frequency resource selection procedure (refer to step S520 of FIG. 5) is satisfied.

In step S620, the MAC entity of the terminal may determine one SL LC in which data to be transmitted exists, and may identify priority (eg, PQI) information associated with the SL LC.

In step S630, the MAC entity of the terminal may determine which frequency resource is configured for the SL LC in step S620 from among a plurality of transmission frequency resources configured for the terminal.

In conjunction with steps S620 and S630, in step S640, the MAC entity of the terminal may reference/obtain parameter-related information available for transmission frequency resource candidate determination, signaled/reported from a predetermined or higher layer/lower layer. The parameter related information may include one or more of a parameter value or a parameter threshold value.

For example, the MAC entity of the terminal may refer/obtain a parameter value and/or a parameter threshold value associated with the PQI while identifying the PQI configured for the SL LC. For example, the MAC entity of the terminal may reference/obtain a communication range value, a transmit-receive distance value, a PDB value, etc. related to the PQI of the SL LC. In addition, the MAC entity of the UE may reference/obtain a CBR threshold related to the PQI of the SL LC, a threshold related to HARQ feedback information, a threshold related to CSI information, a UE speed threshold, and the like.

For example, the MAC entity of the terminal may refer to/obtain a parameter value and/or a parameter threshold value associated with the frequency resource while identifying the frequency resource configured for the SL LC. For example, the MAC entity of the UE may reference/obtain a CBR value related to a frequency resource configured for SL LC, a value related to HARQ feedback information, a value related to CSI information, and the like. In addition, the MAC entity of the terminal may refer to/obtain a communication range threshold, a transmit-receive distance threshold, a PDB threshold, and the like associated with a frequency resource set for the SL LC.

As a further example, the MAC entity of the terminal may reference/obtain parameter values that are not associated with a specific frequency resource (or are common to all frequency resources or determined to be terminal-specific). For example, the MAC entity of the terminal may reference/obtain a value for the speed of the terminal.

In step S650, the MAC entity of the terminal may consider or determine the transmission frequency resource candidate based on one parameter or a combination of two or more parameters among the parameter-related information available for determining the transmission frequency resource candidate. The above-described examples may be applied to conditions for each parameter value and threshold value, and priorities between different parameters.

In step S660, the MAC entity of the terminal may select a predetermined number (n) of frequency resources from among the transmission frequency resource candidates based on the terminal capability. The number of frequency resources finally selected may be 0, 1, or 2 or more, and the number may be determined according to UE capability. In addition, the MAC entity of the terminal may select a resource pool to be used for SL transmission on the selected frequency resource.

In step S670, the MAC entity of the terminal may perform SL data transmission through the physical layer on the selected frequency resource.

7 is a diagram illustrating the configuration of a first terminal device and a second terminal device according to the present disclosure.

The first terminal device 700 may include a processor 710 , an antenna unit 720 , a transceiver 730 , and a memory 740 .

The processor 710 performs baseband-related signal processing and may include an upper layer processing unit 711 and a physical layer processing unit 715 . The higher layer processing unit 711 may process the operation of the MAC layer, the RRC layer, or higher layers. The physical layer processing unit 715 may process operations of the PHY layer (eg, downlink reception signal processing, uplink transmission signal processing, sidelink transmission signal processing, etc.). The processor 710 may control the overall operation of the first terminal device 700 in addition to performing baseband-related signal processing.

The antenna unit 720 may include one or more physical antennas, and when it includes a plurality of antennas, it may support MIMO transmission/reception. The transceiver 730 may include an RF transmitter and an RF receiver. The memory 740 may store information processed by the processor 710 , software related to the operation of the first terminal device 700 , an operating system, an application, and the like, and may include components such as a buffer.

The processor 710 of the first terminal device 700 may be configured to implement the operation of the transmitting terminal in the embodiments described in the present invention.

For example, the upper layer processing unit 711 of the processor 710 of the first terminal device 700 includes the parameter related information determiner 712 , the frequency resource candidate determiner 713 , and the frequency resource selector 714 . may include

When the SL LC identification in which data to be transmitted exists and the frequency resource configured for the SL LC are identified, the parameter-related information determining unit 712 determines a priority (eg, PQI) of the SL LC or a parameter related to the frequency resource. A value or parameter threshold may be determined. These parameter values and thresholds may be used for frequency resource candidate determination. In addition, one or more of these parameters may be set, and each parameter may have a type of the first parameter, the second parameter, or the third parameter in the above-described examples.

When the frequency resource selection for the first terminal device 700 is triggered, the frequency resource candidate determiner 713 uses the parameter value and the threshold determined by the parameter related information determiner 712 to set the frequency for the SL LC. A frequency resource candidate may be determined from among the resources. The frequency resource candidate may be determined based on conditions applied according to various parameter types in the above-described examples.

The frequency resource selector 714 may select a predetermined number of frequency resources from among the frequency resource candidates determined by the frequency resource candidate determiner 713 according to terminal capabilities.

Information indicating the selected frequency resource and data to be transmitted may be transmitted to the physical layer processing unit 715 , and SL data transmission may be performed to the second terminal device 750 .

The second terminal device 750 may include a processor 760 , an antenna unit 770 , a transceiver 780 , and a memory 790 .

The processor 760 performs baseband-related signal processing and may include an upper layer processing unit 761 and a physical layer processing unit 765 . The higher layer processing unit 761 may process operations of the MAC layer, the RRC layer, or higher layers. The physical layer processing unit 765 may process operations of the PHY layer (eg, downlink reception signal processing, uplink transmission signal processing, sidelink reception signal processing, etc.). The processor 760 may control the overall operation of the second terminal device 760 in addition to performing baseband-related signal processing.

The antenna unit 770 may include one or more physical antennas, and when including a plurality of antennas, may support MIMO transmission/reception. The transceiver 780 may include an RF transmitter and an RF receiver. The memory 790 may store information processed by the processor 760 , software related to the operation of the second terminal device 750 , an operating system, an application, and the like, and may include components such as a buffer.

The processor 760 of the second terminal device 750 may be configured to implement the operation of the receiving terminal in the embodiments described in the present invention.

For example, the upper layer processing unit 761 of the processor 760 of the second terminal device 750 may include a geographic information generation unit 762 and a feedback information generation unit 763 .

The geographic information generator 762 may generate geographic information of the second terminal 750 . For example, the geographic information may include information indicating the location, area identifier, and movement speed of the second terminal 750 . Such geographic information may be transmitted to the first terminal 700 through the physical layer processing unit 765 and used to determine parameter-related information of the first terminal 700 .

The feedback information generator 763 may generate information on data/channels received by the second terminal 750 on the sidelink from the first terminal 700 . For example, the feedback information may include HARQ ACK/NACK information, CSI information, and the like. Such feedback information may be transmitted to the first terminal 700 through the physical layer processing unit 765 and used to determine parameter-related information of the first terminal 700 .

In the operation of the first terminal device 700 and the second terminal device 750 , the descriptions of the transmitting terminal and the receiving terminal in the examples of the present invention may be applied in the same manner, and overlapping descriptions will be omitted.

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

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

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

The scope of the present disclosure includes software or machine-executable instructions (eg, operating system, application, firmware, program, etc.) that cause operation according to the method of various embodiments to be executed on a device or computer, and such software or and non-transitory computer-readable media in which instructions and the like are stored and executed on a device or computer.

Claims (1)

A method for a transmitting terminal to select a sidelink frequency resource in a wireless communication system, the method comprising:
triggering frequency resource selection for a sidelink logical channel;
determining a frequency resource candidate based on one or more parameters related to one or more of a priority of the sidelink logical channel or a frequency resource configured for the sidelink logical channel;
selecting one or more frequency resources from among the determined frequency resource candidates; and
Comprising the step of performing transmission to the receiving terminal on the selected frequency resource,
The one or more parameters include one or more of congestion degree, geographic factor, link quality, or feedback information.
Sidelink frequency resource selection method.

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