CN118369976A

CN118369976A - Method and apparatus for transmitting side uplink resource coordination information

Info

Publication number: CN118369976A
Application number: CN202280080160.4A
Authority: CN
Inventors: 李正薰; 金哲淳; 文盛铉
Original assignee: Electronics and Telecommunications Research Institute ETRI
Current assignee: Electronics and Telecommunications Research Institute ETRI
Priority date: 2021-10-26
Filing date: 2022-10-24
Publication date: 2024-07-19

Abstract

An operation method for a first terminal to perform side-link communication may include the steps of: receiving resource coordination information from a second terminal; if the resource coordination information is information on a preferred resource, selecting a candidate resource to be used for transmission of the first terminal by prioritizing the preferred resource; and excluding the non-preferred resource from the candidate resources to be used for transmission of the first terminal if the resource coordination information is information on the non-preferred resource.

Description

Method and apparatus for transmitting side uplink resource coordination information

Technical Field

The present disclosure relates to a side-link communication technology, and more particularly, to a method for transmitting resource coordination information in side-link communication and an apparatus therefor.

Background

In the side uplink communication, even when the resource allocation pattern 2 is used, a terminal (i.e., a coordinating terminal) which coordinates resources for data transmission and reception between terminals and transmits and receives information (i.e., resource coordination information) on the coordinated resources to a terminal (i.e., a coordinated terminal) which needs to perform data transmission and reception can be configured similarly to the base station of the resource allocation pattern 1. Since the terminal performs data transmission and reception operations within the coordinated resources, occurrence of collision between the resources can be prevented and performance can be improved accordingly. Furthermore, energy efficiency may be improved by the terminal performing sensing and selecting operations within limited resources.

Disclosure of Invention

[ Problem ]

The present disclosure relates to providing a method for transmitting resource coordination information for side-link communications.

The present disclosure also relates to a configuration of an apparatus that performs the method for transmitting resource coordination information for side-link communication.

[ Technical solution ]

According to an exemplary embodiment of the present disclosure for achieving the above object, an operation method of a first terminal performing side uplink communication may include: receiving resource coordination information from a second terminal; selecting a candidate resource to be used for transmission of the first terminal by prioritizing the preferred resource in response to the resource coordination information being information on the preferred resource; and excluding non-preferred resources from candidate resources to be used for transmission of the first terminal in response to the resource coordination information being information on non-preferred resources.

The second terminal may be a terminal that receives data transmitted by the first terminal.

The resource coordination information may be received through a Medium Access Control (MAC) Control Element (CE) or through a MAC CE and side-uplink control information (SCI).

Whether the resource coordination information is received through the MAC CE or the MAC CE and SCI may be configured for each resource pool.

The resource coordination information may include N Time Resource Indicator Value (TRIV)/Frequency Resource Indicator Value (FRIV) combinations, each of the N TRIV/FRIV combinations may indicate M resources, each of N and M being a natural number equal to or greater than 1.

The time location and frequency location of a first resource of the M resources indicated by each of the N TRIV/FRIV combinations may also be included in the resource coordination information.

The frequency location of the first resource may be indicated by a starting subchannel index.

The time position of a first resource of the M resources indicated by a first TRIV/FRIV combination of the N TRIV/FRIV combinations may be indicated as a reference slot and the time positions of the first resources in the remaining TRIV/FRIV combinations other than the first TRIV/FRIV combination may be indicated by a slot offset relative to the reference slot.

The resource range indicated by the N TRIV/FRIV combinations when the resource coordination information is received through the MAC CE may be different from the resource range indicated by the N TRIV/FRIV combinations when the resource coordination information is received through the MAC CE and the SCI.

The resource coordination information may be received from the second terminal based on an explicit request of the first terminal or according to satisfaction of a predetermined condition without an explicit request of the first terminal.

According to an exemplary embodiment of the present disclosure for achieving the above object, an operation method of a second terminal performing side uplink communication may include: generating resource coordination information, which is information on preferred resources or non-preferred resources for transmission of the first terminal; and transmitting resource coordination information to the first terminal, wherein when the resource coordination information is information on a preferred resource, a candidate resource to be used for transmission by the first terminal is selected by prioritizing the preferred resource, and when the resource coordination information is information on a non-preferred resource, the non-preferred resource is excluded from the candidate resources to be used for transmission by the first terminal.

The resource coordination information may be transmitted through a Medium Access Control (MAC) Control Element (CE) or through a MAC CE and a side-uplink control information (SCI).

Whether the resource coordination information is transmitted through the MAC CE or the MAC CE and SCI may be configured for each resource pool.

According to an exemplary embodiment of the present disclosure for achieving the above another object, a first terminal performing side uplink communication may include: at least one transceiver; and a processor that controls the at least one transceiver, wherein the processor causes the first terminal to perform: receiving resource coordination information from the second terminal by using the transceiver; selecting a candidate resource to be used for transmission of the first terminal by prioritizing the preferred resource in response to the resource coordination information being information on the preferred resource; and excluding the non-preferred resource from the candidate resources to be used for transmission of the first terminal in response to the resource coordination information being information on the non-preferred resource.

The resource coordination information may include N Time Resource Indication Value (TRIV)/frequency resource indication value combinations, each of the N TRIV/FRIV combinations may indicate M resources, each of N and M being a natural number equal to or greater than 1.

[ Beneficial effects ]

According to the exemplary embodiments of the present disclosure, side uplink resource coordination information can be efficiently transmitted. Thus, the overall performance of the communication system can be improved.

Drawings

Fig. 1 is a conceptual diagram illustrating a first exemplary embodiment of a communication system.

Fig. 2 is a block diagram showing a first exemplary embodiment of a communication node constituting a communication system.

Fig. 3 is a conceptual diagram illustrating a first exemplary embodiment of a type 1 frame.

Fig. 4 is a conceptual diagram illustrating a first exemplary embodiment of a type 2 frame.

Fig. 5 is a conceptual diagram illustrating a first exemplary embodiment of a transmission method of an SS/PBCH block in a communication system.

Fig. 6 is a conceptual diagram illustrating a first exemplary embodiment of an SS/PBCH block in a communications system.

Fig. 7 is a conceptual diagram illustrating a second exemplary embodiment of a method of transmitting SS/PBCH blocks in a communication system.

Fig. 8A is a conceptual diagram illustrating RMSI CORESET mapping mode #1 in a communication system, fig. 8B is a conceptual diagram illustrating RMSI CORESET mapping mode #2 in a communication system, and fig. 8C is a conceptual diagram illustrating RMSI CORESET mapping mode #3 in a communication system.

Fig. 9 is a conceptual diagram for describing an example of PSFCH resources configured for transmission of HARQ ACK/NACK information.

Fig. 10 is a conceptual diagram illustrating an exemplary embodiment of a method for multiplexing control channels and data channels in side-link communications.

Fig. 11 is a conceptual diagram for describing a first exemplary embodiment of a resource coordination information signaling method according to the present disclosure.

Fig. 12 is a conceptual diagram for describing a second exemplary embodiment of a resource coordination information signaling method according to the present disclosure.

Fig. 13 is a conceptual diagram for describing an exemplary embodiment of a method of determining a transmission time of CI-PSFCH based on a slot in which a PSSCH predicted to have a collision is to be transmitted.

Fig. 14 is a conceptual diagram for describing an exemplary embodiment of a method for determining the transmission time of CI-PSFCH based on the time slot in which the SCI for predicting collision is transmitted.

Detailed Description

Exemplary embodiments of the present disclosure are disclosed herein. However, specific structural and functional details disclosed herein are merely representative for purposes of describing embodiments of the present disclosure. Thus, embodiments of the present disclosure may be embodied in many alternate forms and should not be construed as limited to the embodiments of the present disclosure set forth herein.

Thus, while the disclosure is susceptible to various modifications and alternative forms, specific embodiments thereof have been shown by way of example in the drawings and will herein be described in detail. It should be understood, however, that there is no intent to limit the disclosure to the particular forms disclosed, but on the contrary, the disclosure is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the disclosure. Like reference numerals refer to like elements throughout the description of the drawings.

It will be understood that, although the terms first, second, etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another element. For example, a first element could be termed a second element, and, similarly, a second element could be termed a first element, without departing from the scope of the present disclosure. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.

In exemplary embodiments of the present disclosure, "at least one of a and B" may refer to "at least one of a or B" or "at least one of a combination of one or more of a and B". Further, in exemplary embodiments of the present disclosure, "one or more of a and B" may refer to "one or more of a or B" or "one or more of a and B in combination.

In exemplary embodiments of the present disclosure, "(re) transmission" may refer to "transmission", "retransmission" or "transmission and retransmission", "(re) configuration" may refer to "configuration", "reconfiguration" or "configuration and reconfiguration", "(re) connection" may refer to "connection", "reconnection" or "connection and reconnection", and "(re) access" may refer to "access", "revisit" or "access and revisit".

It will be understood that when an element is referred to as being "connected" or "coupled" to another element, it can be directly connected or coupled to the other element or intervening elements may be present. In contrast, when an element is referred to as being "directly connected" or "directly coupled" to another element, there are no intervening elements present. Other words used to describe the relationship between elements should be interpreted in a similar fashion (i.e., "between" and "directly between", "adjacent" and "directly adjacent", etc.).

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the disclosure. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises," "comprising," "includes" and/or "including," when used herein, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.

Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

Hereinafter, exemplary embodiments of the present disclosure will be described in more detail with reference to the accompanying drawings. In order to facilitate a general understanding in describing the present disclosure, like parts in the drawings are denoted by like reference numerals, and a repetitive description thereof will be omitted.

A communication system to which the exemplary embodiments according to the present disclosure are applied will be described. The communication system to which the exemplary embodiments according to the present disclosure are applied is not limited to the following description, and the exemplary embodiments according to the present disclosure may be applied to various communication systems. Here, the communication system can be used in the same sense as the communication network.

Referring to fig. 1, a communication system 100 may include a plurality of communication nodes 110-1, 110-2, 110-3, 120-1, 120-2, 130-1, 130-2, 130-3, 130-4, 130-5, and 130-6. Furthermore, the communication system 100 may also include a core network (e.g., a serving gateway (S-GW), a Packet Data Network (PDN) gateway (P-GW), and a Mobility Management Entity (MME)). When the communication system 100 is a 5G communication system (e.g., a New Radio (NR) system), the core network may include an access and mobility management function (AMF), a User Plane Function (UPF), a Session Management Function (SMF), and the like.

The plurality of communication nodes 110 to 130 may support communication protocols (e.g., LTE communication protocol, LTE-a communication protocol, NR communication protocol, etc.) defined by third generation partnership project (3 GPP) specifications. The plurality of communication nodes 110 through 130 may support Code Division Multiple Access (CDMA) technology, wideband CDMA (WCDMA) technology, time Division Multiple Access (TDMA) technology, frequency Division Multiple Access (FDMA) technology, orthogonal Frequency Division Multiplexing (OFDM) technology, filtered OFDM technology, cyclic prefix OFDM (CP-OFDM) technology, discrete fourier transform spread OFDM (DFT-s-OFDM) technology, orthogonal Frequency Division Multiple Access (OFDMA) technology, single carrier FDMA (SC-FDMA) technology, non-orthogonal multiple access (NOMA) technology, generalized Frequency Division Multiplexing (GFDM) technology, filtered band multi-carrier (FBMC) technology, universal filtered multi-carrier (UFMC) technology, spatial Division Multiple Access (SDMA) technology, and the like. Each of the plurality of communication nodes may have the following structure.

Referring to fig. 2, a communication node 200 may include at least one processor 210, a memory 220, and a transceiver 230 connected to a network to perform communication. In addition, the communication node 200 may also include an input interface device 240, an output interface device 250, a storage device 260, and the like. Each of the components included in communication node 200 may communicate with each other when connected by bus 270.

However, each component included in the communication node 200 may not be connected to the common bus 270, but may be connected to the processor 210 via a separate interface or respective buses. For example, the processor 210 may be connected to at least one of the memory 220, the transceiver 230, the input interface device 240, the output interface device 250, and the storage device 260 via a dedicated interface.

The processor 210 may execute programs stored in at least one of the memory 220 and the storage device 260. Processor 210 may refer to a Central Processing Unit (CPU), a Graphics Processing Unit (GPU), or a special-purpose processor on which methods according to embodiments of the present disclosure are performed. Each of the memory 220 and the storage device 260 may be composed of at least one of a volatile storage medium and a nonvolatile storage medium. For example, the memory 220 may include at least one of Read Only Memory (ROM) and Random Access Memory (RAM).

Referring again to fig. 1, the communication system 100 may include a plurality of base stations 110-1, 110-2, 110-3, 120-1, and 120-2, and a plurality of terminals 130-1, 130-2, 130-3, 130-4, 130-5, and 130-6. Each of the first, second and third base stations 110-1, 110-2 and 110-3 may form a macrocell, and each of the fourth and fifth base stations 120-1 and 120-2 may form a microcell. The fourth base station 120-1, the third terminal 130-3, and the fourth terminal 130-4 may belong to the cell coverage of the first base station 110-1. In addition, the second terminal 130-2, the fourth terminal 130-4, and the fifth terminal 130-5 may belong to the cell coverage of the second base station 110-2. In addition, the fifth base station 120-2, the fourth terminal 130-4, the fifth terminal 130-5, and the sixth terminal 130-6 may belong to the cell coverage of the third base station 110-3. In addition, the first terminal 130-1 may belong to the cell coverage of the fourth base station 120-1, and the sixth terminal 130-6 may belong to the cell coverage of the fifth base station 120-2.

Here, each of the plurality of base stations 110-1, 110-2, 110-3, 120-1, and 120-2 may refer to a Node-B (NB), an evolved Node-B (eNB), a gNB, an Advanced Base Station (ABS), a high reliability base station (HR-BS), a Base Transceiver Station (BTS), a radio base station, a radio transceiver, an access point, an access Node, a Radio Access Station (RAS), a mobile multi-hop relay base station (MMR-BS), a Relay Station (RS), an Advanced Relay Station (ARS), a high reliability relay station (HR-RS), a Home NodeB (HNB), a home eNodeB (HeNB), a roadside unit (RSU), a Radio Remote Head (RRH), a Transmission Point (TP), a Transmission and Reception Point (TRP), and the like.

Each of the plurality of terminals 130-1, 130-2, 130-3, 130-4, 130-5, and 130-6 may refer to a User Equipment (UE), a Terminal Equipment (TE), an Advanced Mobile Station (AMS), a high reliability mobile station (HR-MS), a terminal, an access terminal, a mobile terminal, a station, a subscriber station, a mobile station, a portable subscriber station, a node, a device, an on-board unit (OBU), and the like.

Meanwhile, each of the plurality of base stations 110-1, 110-2, 110-3, 120-1, and 120-2 may operate in the same frequency band or different frequency bands. The plurality of base stations 110-1, 110-2, 110-3, 120-1, and 120-2 may be connected to each other via an ideal backhaul or a non-ideal backhaul, and exchange information with each other via the ideal backhaul or the non-ideal backhaul. In addition, each of the plurality of base stations 110-1, 110-2, 110-3, 120-1, and 120-2 may be connected to the core network through an ideal backhaul or a non-ideal backhaul. Each of the plurality of base stations 110-1, 110-2, 110-3, 120-1, and 120-2 may transmit a signal received from the core network to a corresponding terminal 130-1, 130-2, 130-3, 130-4, 130-5, or 130-6, and transmit a signal received from a corresponding terminal 130-1, 130-2, 130-3, 130-4, 130-5, or 130-6 to the core network.

Further, each of the plurality of base stations 110-1, 110-2, 110-3, 120-1, and 120-2 may support multiple-input multiple-output (MIMO) transmission (e.g., single-user MIMO (SU-MIMO), multi-user MIMO (MU-MIMO), or massive MIMO, etc.), coordinated multi-point (CoMP) transmission, carrier Aggregation (CA) transmission, transmission in an unlicensed band, device-to-device (D2D) communication (or proximity services (ProSe)), internet of things (IoT) communication, dual Connectivity (DC), and so forth. Here, each of the plurality of terminals 130-1, 130-2, 130-3, 130-4, 130-5, and 130-6 may perform operations corresponding to the operations of the plurality of base stations 110-1, 110-2, 110-3, 120-1, and 120-2 (i.e., operations supported by the plurality of base stations 110-1, 110-2, 110-3, 120-1, and 120-2). For example, the second base station 110-2 may transmit signals to the fourth terminal 130-4 in SU-MIMO mode, and the fourth terminal 130-4 may receive signals from the second base station 110-2 in SU-MIMO mode. Or the second base station 110-2 may transmit signals to the fourth terminal 130-4 and the fifth terminal 130-5 in MU-MIMO, and the fourth terminal 130-4 and the fifth terminal 130-5 may receive signals from the second base station 110-2 in MU-MIMO.

The first base station 110-1, the second base station 110-2, and the third base station 110-3 may transmit signals to the fourth terminal 130-4 in a CoMP transmission manner, and the fourth terminal 130-4 may receive signals from the first base station 110-2, the second base station 110-2, and the third base station 110-3 in a CoMP manner. Furthermore, each of the plurality of base stations 110-1, 110-2, 110-3, 120-1, and 120-2 may exchange signals with a corresponding terminal 130-1, 130-2, 130-3, 130-4, 130-5, or 130-6 belonging to its cell coverage in a CA manner. Each of the base stations 110-1, 110-2, and 110-3 may control D2D communication between the fourth terminal 130-4 and the fifth terminal 130-5, and thus the fourth terminal 130-4 and the fifth terminal 130-5 may perform D2D communication under the control of the second base station 110-2 and the third base station 110-3.

Meanwhile, the communication system can support three types of frame structures. The type 1 frame structure may be applied to a Frequency Division Duplex (FDD) communication system, the type 2 frame structure may be applied to a Time Division Duplex (TDD) communication system, and the type 3 frame structure may be applied to an unlicensed band-based communication system (e.g., a Licensed Assisted Access (LAA) communication system).

Referring to fig. 3, a radio frame 300 may include 10 subframes, and one subframe may include 2 slots. Thus, the radio frame 300 may include 20 slots (e.g., slot #0, slot #1, slot #2, slot #3, …, slot #18, and slot # 19). The length T _f of the radio frame 300 may be 10 milliseconds (ms). The length of the subframe may be 1ms and the length T _slot of the slot may be 0.5ms. Here, T _s may indicate a sampling time, and may be 1/30,720,000s.

A slot may be composed of a plurality of OFDM symbols in the time domain and may be composed of a plurality of Resource Blocks (RBs) in the frequency domain. An RB may be composed of a plurality of subcarriers in the frequency domain. The number of OFDM symbols constituting a slot may vary according to the configuration of a Cyclic Prefix (CP). CPs can be classified into normal CPs and extended CPs. If normal CP is used, the slot may consist of 7 OFDM symbols, in which case the subframe may consist of 14 OFDM symbols. If extended CP is used, the slot may be composed of 6 OFDM symbols, in which case the subframe may be composed of 12 OFDM symbols.

Referring to fig. 4, a radio frame 400 may include two fields, and one field may include 5 subframes. Thus, the radio frame 400 may include 10 subframes. The length T _f of the radio frame 400 may be 10ms. The half frame may be 5ms in length. The length of the subframe may be 1ms. Here, T _s may be 1/30,720,000s.

The radio frame 400 may include at least one downlink subframe, at least one uplink subframe, and at least one special subframe. Each of the downlink subframe and the uplink subframe may include two slots. The length T _slot of the slot may be 0.5ms. Of subframes included in the radio frame 400, each of the subframe #1 and the subframe #6 may be a special subframe. For example, when the switching period between downlink and uplink is 5ms, the radio frame 400 may include 2 special subframes. Or the switching period between downlink and uplink is 10ms, the radio frame 400 may include one special subframe. The special subframe may include a downlink pilot time slot (DwPTS), a Guard Period (GP), and an uplink pilot time slot (UpPTS).

The downlink pilot time slots may be considered as downlink intervals and may be used for cell search, time and frequency synchronization acquisition of terminals, channel estimation, etc. The guard period may be used to solve the interference problem of uplink data transmission caused by the delay of downlink data reception. Further, the guard period may include a time required to switch from the downlink data reception operation to the uplink data transmission operation. The uplink pilot time slots may be used for uplink channel estimation, time and frequency synchronization acquisition, etc. Transmission of a Physical Random Access Channel (PRACH) or a Sounding Reference Signal (SRS) may be performed in an uplink pilot slot.

The lengths of the downlink pilot time slot, the guard period, and the uplink pilot time slot included in the special subframe may be variably adjusted as needed. Further, the number and position of each of the downlink, uplink, and special subframes included in the radio frame 400 may be changed as needed.

In a communication system, a Transmission Time Interval (TTI) may be a basic time unit for transmitting encoded data through a physical layer. Short TTIs can be used to support low latency requirements in a communications system. The short TTI may be less than 1ms in length. A conventional TTI having a length of 1ms may be referred to as a basic TTI or a conventional TTI. That is, the basic TTI may be composed of one subframe. To support transmission on a basic TTI basis, signals and channels may be configured on a subframe basis. For example, a cell-specific reference signal (CRS), a Physical Downlink Control Channel (PDCCH), a Physical Downlink Shared Channel (PDSCH), a Physical Uplink Control Channel (PUCCH), a Physical Uplink Shared Channel (PUSCH), etc. may be present in each subframe.

On the other hand, there may be one synchronization signal (e.g., primary Synchronization Signal (PSS) and Secondary Synchronization Signal (SSS)) every 5 subframes, and there may be one Physical Broadcast Channel (PBCH) every 10 subframes. Further, each radio frame can be identified by an SFN, and the SFN can be used to define transmission of signals longer than one radio frame (e.g., paging signals, reference signals for channel estimation, signals for channel state information, etc.). The period of the SFN may be 1024.

In the LTE system, the PBCH may be a physical layer channel for transmitting system information, e.g., a Master Information Block (MIB). The PBCH may be transmitted once every 10 subframes. That is, the transmission period of the PBCH may be 10ms, and the PBCH may be transmitted once in one radio frame. The same MIB may be transmitted during 4 consecutive radio frames, and after 4 consecutive radio frames, the MIB may be changed according to the case of the LTE system. The transmission period for transmitting the same MIB may be referred to as a "PBCH TTI", which may be 40ms. That is, the MIB may vary for each PBCH TTI.

The MIB may consist of 40 bits. Of the 40 bits constituting the MIB, 3 bits may be used to indicate a system band, 3 bits may be used to indicate physical hybrid automatic repeat request (ARQ) indicator channel (PHICH) related information, 8 bits may be used to indicate SFN,10 bits may be configured as reserved bits, and 16 bits may be used for Cyclic Redundancy Check (CRC).

The SFN for identifying the radio frame may be composed of 10 bits (B9 to B0) in total, and the Most Significant Bit (MSB) 8 bits (B9 to B2) among the 10 bits may be indicated by a PBCH (i.e., MIB). The MSB 8 bits (B9 to B2) of the SFN indicated by the PBCH (i.e., MIB) may be identical during consecutive 4 radio frames (i.e., PBCH TTI). The Least Significant Bits (LSB) 2 bits (B1 to B0) of the SFN may change during consecutive 4 radio frames (i.e., PBCH TTI) and may not be explicitly indicated by the PBCH (i.e., MIB). The LSB (2 bits (B1 to B0)) of the SFN may be implicitly indicated by a scrambling sequence of the PBCH (hereinafter referred to as "PBCH scrambling sequence").

The Gold sequence generated by the initialization of the cell ID may be used as a PBCH scrambling sequence, and the PBCH scrambling sequence may be initialized for every four consecutive radio frames (e.g., every PBCH TTI) based on the operation of "mod (SFN, 4)". The PBCH transmitted in the radio frame corresponding to the SFN in which LSB 2 bits (B1 to B0) are set to "00" may be scrambled by a Gold sequence generated by cell ID initialization. Thereafter, a Gold sequence generated according to the operation of "mod (SFN, 4)" may be used to scramble PBCH transmitted in radio frames corresponding to SFNs in which LSB 2 bits (B1 to B0) are set to "01", "10", and "11".

Accordingly, the terminal having acquired the cell ID in the initial cell search process can identify the value (e.g., '00', '01', '10', or '11') of LSB 2 bits (B1 to B0) of the SFN based on the PBCH scrambling sequence obtained in the decoding process of the PBCH (i.e., MIB). The terminal may use LSB 2 bits (B1 to B0) of the SFN obtained based on the PBCH scrambling sequence and MSB 8 bits (B9 to B2) of the SFN indicated by the PBCH (i.e., MIB) in order to identify the SFN (e.g., all bits B9 to B0 of the SFN).

The evolution mobile communication network after LTE should meet the technical requirements of supporting more diverse service scenarios and high transmission rates, which is a major problem in the prior art. Recently, ITU-R defines Key Performance Indicators (KPIs) and requirements of IMT-2020 (official name of 5G mobile communication), which are summarized as high transmission rate (i.e. enhanced mobile broadband (eMBB)), short transmission delay (i.e. ultra-reliable low-delay communication (URLLC)) and large-scale terminal connectivity (i.e. large-scale machine type communication (mMTC)). The goal is to assign frequencies to IMT-2020 in 2019 and to complete international standard approval before 2020 according to ITU-R's schedule.

The 3GPP is developing a new Radio Access Technology (RAT) -based 5G standard that meets the requirements of IMT-2020. According to the definition of 3GPP, the new RAT is a radio access technology that does not have backward compatibility with existing 3GPP RATs. The new radio communication system after LTE employing such a RAT is referred to as New Radio (NR) in this disclosure.

One of the features of NR different from CDMA and LTE, which are conventional 3GPP systems, is that it increases transmission capacity using a wide range of frequency bands. In this regard, the ITU-mediated WRC-19 agenda is examining the 24.25 to 86GHz band as a candidate band for IMT-2020. In 3GPP, a band from a band below 1GHz to a band of 100GHz is considered as a candidate NR band.

As the waveform technique of NR, orthogonal Frequency Division Multiplexing (OFDM), filtered OFDM, generalized Frequency Division Multiplexing (GFDM), filter Bank Multicarrier (FBMC), universal filtered multicarrier (ufm|c), and the like are discussed as candidate techniques. Despite the advantages and disadvantages of each scheme, cyclic Prefix (CP) based OFDM and single carrier frequency division multiple access (SC-FDMA) remain effective schemes for 5G systems because of their relatively low implementation complexity at the transceiver and Multiple Input Multiple Output (MIMO) scalability. However, in order to flexibly support various 5G usage scenarios, a method of accommodating different waveform parameters simultaneously within one carrier without guard bands may be considered, and for this case, filtered OFDM or GFDM with low out-of-band emissions (OOB) may be suitable.

In the present disclosure, for convenience of description, it is assumed that CP-based OFDM is used as a waveform technique for radio access. However, this is merely for convenience of description, and various exemplary embodiments of the present disclosure are not limited to a particular waveform technique. In general, the class of CP-based OFDM techniques includes filtered OFDM or spread OFDM (e.g., DFT spread OFDM) techniques.

The subcarrier spacing of a communication system (e.g., an OFDM-based communication system) may be determined based on a Carrier Frequency Offset (CFO) or the like. CFOs may be generated by doppler effect, phase shift, etc., and may increase in proportion to the operating frequency. Accordingly, in order to prevent performance degradation of the communication system due to CFO, the subcarrier spacing may increase in proportion to the operating frequency. On the other hand, as the subcarrier spacing increases, CP overhead may increase. Accordingly, the subcarrier spacing may be configured based on channel characteristics, radio Frequency (RF) characteristics, and the like according to the frequency band.

Various digital techniques are being considered in NR systems. For example, the subcarrier spacing of the communication system may be configured to be 15kHz, 30kHz, 60kHz, or 120kHz. The subcarrier spacing of the LTE system may be 15kHz, and the subcarrier spacing of the NR system may be 1,2, 4, or 8 times the conventional subcarrier spacing of 15 kHz. If the subcarrier spacing is increased in power units of 2 of the conventional subcarrier spacing, the frame structure can be easily designed.

The communication system may support a wide frequency band (e.g., hundreds of MHz to tens of GHz). Since the diffraction characteristic and reflection characteristic of radio waves are poor in the high frequency band, propagation loss (e.g., path loss, reflection loss, etc.) in the high frequency band may be larger than that in the low frequency band. Thus, the cell coverage of a communication system supporting a high frequency band may be smaller than the cell coverage of a communication system supporting a low frequency band. To solve such a problem, a beamforming scheme based on a plurality of antenna elements may be used to increase a cell coverage in a communication system supporting a high frequency band.

The beamforming schemes may include a digital beamforming scheme, an analog beamforming scheme, a hybrid beamforming scheme, and the like. In communication systems using digital beamforming schemes, multiple RF paths based on a digital precoder or codebook may be used to obtain beamforming gain. In communication systems using analog beamforming schemes, an analog RF device (e.g., phase shifter, power Amplifier (PA), variable Gain Amplifier (VGA), etc.) and antenna array may be used to obtain beamforming gain.

Since digital beamforming schemes and transceiver units corresponding to the number of antenna elements require expensive digital-to-analog converters (DACs) or analog-to-digital converters (ADCs), the complexity of the antenna implementation may increase to increase the beamforming gain. In the case of a communication system using an analog beamforming scheme, since a plurality of antenna elements are connected to one transceiver unit through phase shifters, the complexity of antenna implementation does not greatly increase even if the beamforming gain increases. However, the beamforming performance of a communication system using an analog beamforming scheme may be lower than that of a communication system using a digital beamforming scheme. Furthermore, in a communication system using an analog beamforming scheme, since the phase shifter is adjusted in the time domain, frequency resources may not be used efficiently. Thus, a hybrid beamforming scheme may be used that is a combination of a digital scheme and an analog scheme.

When the cell coverage is increased by using the beamforming scheme, common control channels and common signals (e.g., reference signals and synchronization signals) of all terminals belonging to the cell coverage as well as control channels and data channels of each terminal may also be transmitted based on the beamforming scheme. In the case where a common control channel or signal is transmitted to all terminals while increasing cell coverage by applying beamforming, it may be difficult to transmit the common control channel or signal to the entire cell coverage through a single transmission, and the common control channel or signal should be transmitted multiple times through multiple beams. A scheme in which a channel or signal is transmitted multiple times over different beams over a period of time may be referred to as beam scanning. Such beam scanning operation is absolutely necessary when transmitting common control channels or signals by applying beam forming.

A terminal desiring to access the system can acquire downlink frequency/time synchronization and cell ID information using a synchronization signal, acquire uplink synchronization through a random access procedure, and form a radio link. In this case, in the NR system, a synchronization signal/physical broadcast channel (SS/PBCH) block may also be transmitted in a beam scanning scheme. The SS/PBCH block may consist of PSS, SSS, PBCH or the like. In the SS/PBCH block, PSS, SSs, and PBCH may be configured in a Time Division Multiplexing (TDM) manner. The SS/PBCH block may also be referred to as an "SS block (SSB)". One SS/PBCH block may be transmitted using N consecutive OFDM symbols. Here, N may be an integer equal to or greater than 4. The base station may periodically transmit SS/PBSCH blocks and the terminal may acquire frequency/time synchronization, cell ID, system information, etc., based on the SS/PBCH blocks received from the base station. The SS/PBCH block may be transmitted as follows.

Referring to fig. 5, one or more SS/PBCH blocks may be transmitted in a beam scanning scheme within a SS/PBCH block burst set. Up to L SS/PPBCH blocks may be transmitted within one SS/PBCH block burst set. L may be an integer equal to or greater than 2 and may be defined in the 3GPP standard. L may vary depending on the region of system frequencies. Within the SS/PBCH block burst set, SS/PBCH blocks may be distributed continuously or discretely. Successive SS/PBCH blocks may be referred to as "SS/PBCH block bursts". The SS/PBCH block burst set may be repeated periodically and system information (e.g., MIB) transmitted through PBCHs of SS/PBCCH blocks within the SS/PBCH block burst set may be the same. The index of the SS/PBCH block, the index of the SS/PBCH block burst, the index of the OFDM symbol, the index of the slot, etc. may be indicated explicitly or implicitly by the PBCH.

Referring to fig. 6, signals and channels are arranged in an SS/PBCH block in the order of "pss→pbch→sss→pbch". PSS, SSs, and PBCH within an SS/PBCH block may be configured in a TDM scheme. In the symbol where the SSS is located, the PBCH may be located in frequency resources above the SSS and frequency resources below the SSS. That is, the PBCH may be transmitted in two end bands adjacent to the band in which the SSS is transmitted. When the maximum number of SS/PBCH blocks in the frequency band below 6GHz is 8, SS/PBCH block indexes may be identified based on demodulation reference signals (hereinafter referred to as "PBCH DMRS") for demodulating the PBCH. When the maximum number of SSBs in the frequency band exceeding 6GHz is 64, LSB 3 bits among 6 bits representing the SS/PBCH block index may be identified based on the PBCH DMRS, and the remaining MSB 3 bits may be identified based on the payload of the PBCH.

The maximum system bandwidth that can be supported in an NR system may be 400MHz. The size of the maximum bandwidth that a terminal can support may vary depending on the capabilities of the terminal. Accordingly, the terminal may perform an initial access procedure (e.g., an initial connection procedure) by using some system bandwidths of the NR system supporting the broadband. To support the access procedure of terminals supporting various bandwidth sizes, SS/PBCH blocks may be multiplexed in the frequency domain within the system bandwidth of an NR system supporting a wideband. In this case, the SS/PBCH block may be transmitted as follows.

Referring to fig. 7, a wideband Component Carrier (CC) may include a plurality of bandwidth parts (BWP). For example, the broadband CC may include 4 BWPs. The base station may transmit SS/PBCH blocks in the corresponding BWP #0 to #3 belonging to the wideband CC. The terminal may receive SS/PBCH blocks from one or more BWP among BWP #0 to #3 and may perform an initial access procedure using the received SS/PBCCH blocks.

After detecting the SS/PBCH block, the terminal may acquire system information (e.g., remaining Minimum System Information (RMSI)), and may perform a cell access procedure based on the system information. RMSI may be transmitted on PDSCH scheduled by PDCCH. Configuration information of the control resource set (CORESET), in which a PDCCH including scheduling information of a PDSCH via which RMSI is transmitted, may be transmitted on a PBCH within the SS/PBCH block. Multiple SS/PBCH blocks may be transmitted throughout the system band, and one or more of the multiple SS/PBCH blocks may be SS/PBCH blocks associated with RMSI. The remaining SS/PBCH blocks may not be associated with RMSI. The SS/PBCH block associated with RMSI may be defined as a "cell-defined SS/PBCH block". The terminal may perform a cell search procedure and an initial access procedure by using a cell definition SS/PBCH block. SS/PBCH blocks not associated with RMSI may be used for synchronization procedures and/or measurement procedures in the corresponding BWP. The BWP over which SS/PBCH blocks are transmitted may be limited to one or more BWP within the wide bandwidth.

RMSI may be obtained by performing an operation of obtaining configuration information of CORESET from SS/PBCH blocks (e.g., PBCH), an operation of detecting PDCCH based on the configuration information of CORESET, an operation of obtaining scheduling information of PDSCH from PDCCH, and an operation of receiving RMSI through PDSCH. The transmission resources of the PDCCH may be configured through the configuration information of CORESET. The mapping pattern of RMSI CORESET patterns may be defined as follows. RMSI CORESET may be CORESET for transmitting and receiving RMSI.

Referring to fig. 8A to 8C, one RMSI CORESET mapping mode of RMSI CORESET mapping modes #1 to #3 may be used, and a detailed configuration according to the one RMSI CORESET mapping mode may be determined. In RMSI CORESET map mode #1, SS/PBCH blocks, CORESET (i.e., RMSI CORESET), and PDSCH (i.e., RMSIPDSCH) may be configured in a TDM scheme. RMSIPDSCH may refer to PDSCH through which RMSI is transmitted. In RMSI CORESET map mode #2, CORESET (i.e., RMSI CORESET) and PDSCH (i.e., RMSIPDSCH) may be configured in a TDM scheme, and PDSCH (i.e., RMSIPPDSCH) and SS/PBCH blocks may be configured in a Frequency Division Multiplexing (FDM) scheme. In RMSI CORESET map mode #3, CORESET (i.e., RMSI CORESET) and PDSCH (i.e., RMSIPDSCH) may be configured in a TDM scheme, and CORESET (i.e., RMSI CORESET) and PDSCH (i.e., RMSIPDSCH) may be multiplexed with SS/PBCH blocks in an FDM scheme.

In a frequency band of 6GHz or less, only RMSI CORESET mapping mode #1 may be used. In a frequency band of 6GHz or higher, all RMSI CORESET mapping modes #1, #2, and #3 can be used. The parameter set of the SS/PBCH block may be different from the parameter sets of RMSI CORESET and RMSIPDSCH. Here, the parameter set may be a subcarrier spacing. In RMSI CORESET map mode #1, a combination of all parameter sets may be used. In RMSI CORESET map mode #2, a combination of parameter sets (120 khz,60 khz) or (240 khz,120 khz) may be used for SS/PBCH blocks and RMSI CORESET/PDSCH. In RMSI CORESET map mode #3, a combination of parameter sets (120 kHz ) may be used for SS/PBCH blocks and RMSI CORESET/PDSCH.

One RMSI CORESET mapping mode may be selected from RMSI CORESET mapping modes #1 to #3 according to a combination of the parameter set of the SS/PBCH block and the parameter set of RMSI CORESET/PDSCH. RMSI CORESET may include table a and table B. Table a may represent the number of Resource Blocks (RBs) RMSI CORRESET, the number of symbols of RMSI CORESET, and the offset between RBs of the SS/PBCH block (e.g., start RB or end RB) and RBs of RMSI CORESET (e.g., start RB or end RB). Table B may represent the number of search space sets per slot, the offset of RMSI CORESET, and the OFDM symbol index in each RMSI CORESET mapping mode. Table B may represent information for configuring the monitoring opportunities of RMSIPDCCH. Each of tables a and B may be composed of a plurality of sub-tables. For example, table A may include sub-tables 13-1 through 13-8 defined in Technical Specification (TS) 38.213, while Table B may include sub-tables 13-9 through 13-13 defined in TS 38.213. The size of each of tables a and B may be 4 bits.

In an NR system, PDSCH may be mapped to the time domain according to PDSCH mapping type a or PDSCH mapping class B. PDSCH mapping types a and B may be defined as table 2 below.

TABLE 1

Type a (i.e., PDSCH mapping type a) may be slot-based transmissions. When type a is used, the position of the starting symbol of the PDSCH may be configured as one of {0,1,2,3 }. When the type a and the normal CP are used, the number of symbols constituting the PDSCH (e.g., the duration of the PDSCH) may be configured as one of 3 to 14 within a range not exceeding the slot boundary. Type B (i.e., PDSCH mapping type B) may be a non-slot based transmission. When type B is used, the position of the starting symbol of the PDSCH may be configured as one of 0 to 12. When the type B and normal CP are used, the number of symbols constituting the PDSCH (e.g., the duration of the PDSCH) may be configured as one of {2,4,7} within a range not exceeding the slot boundary. The DMRS (hereinafter referred to as "PDSCH DMRS") for demodulating the PDSCH (e.g., data) may be determined by a value and a length of an ID indicating a PDSCH mapping type (e.g., type a or type B). The ID may be defined differently according to the PDSCH mapping type.

As NR phase 1 normalization is completed in release 15 and NR phase 2 normalization begins at release 16, new features of the NR system are being discussed. One of the representative features is NR unauthorized (U). NR-U is a technology supporting operation in unlicensed spectrum such as Wi-Fi to increase network capacity by increasing the utilization of limited frequency resources. For such operations in unlicensed spectrum, standardization starts with LTE Licensed Assisted Access (LAA) technology release 13 and continues to evolve through LTE-advanced LAA (eLAA) release 14 and LTE-advanced LAA (FeLAA) release 15. In NR, after the NR-U Study (SI), a normalization work is in progress as a Work Item (WI) in version 16.

In the NR-U system, a terminal may determine whether a signal is transmitted from a base station based on a Discovery Reference Signal (DRS) received from a corresponding base station in the same manner as in a general NR system. In an NR-U system in a Standalone (SA) mode, a terminal may acquire synchronization and/or system information based on a DRS. Under an NR-U system, DRSs may be transmitted according to a specification of an unlicensed band (e.g., a transmission band, transmission power, transmission time, etc.). For example, the signal may be configured and/or transmitted to occupy 80% (e.g., 20 MHz) of the total channel bandwidth, as specified by the Occupied Channel Bandwidth (OCB).

In an NR-U system, a communication node (e.g., base station, terminal) may perform a Listen Before Talk (LBT) procedure before transmitting signals and/or channels for coexistence with another system. The signal may be a synchronization signal, a reference signal (e.g., DRS, DMRS, channel State Information (CSI) -RS, phase Tracking (PT) -RS, and Sounding Reference Signal (SRS)), etc. The channel may be a downlink channel, an uplink channel, a side-link channel, etc. In an exemplary embodiment, a signal may refer to a "signal," channel, "or" signal and channel. The LBT procedure may be an operation for checking whether a signal is transmitted by another communication node. If it is determined by the LBT procedure that there is no transmission signal (e.g., when the LBT procedure is successful), the communication node may transmit a signal in an unlicensed frequency band. If it is determined by the LBT procedure that there is a transmission signal (e.g., when LBT fails), the communication node may not be able to transmit the signal in an unlicensed frequency band. The communication node may perform an LBT procedure according to one of various categories prior to transmitting the signal. The type of LBT may vary depending on the type of signal transmitted.

Another representative feature of stage 2, 16 th edition, is NR-Internet of vehicles (V2X). V2X is a technology that supports communication in various scenarios such as vehicle-to-vehicle, vehicle and infrastructure, vehicle and pedestrian based on LTE device-to-device (D2D) communication. Much discussion has been made on V2X communication in LTE systems, and it is still continuing to develop even now. In NR, with the beginning of version 16, the discussion regarding NR V2X has begun.

NR V2X communication (e.g., side-link communication) may be performed according to three transmission schemes (e.g., a unicast scheme, a broadcast scheme, a multicast scheme). When the unicast scheme is used, a PC5-RRC connection may be established between a first terminal (e.g., a transmitting terminal that transmits data) and a second terminal (e.g., a receiving terminal that receives data), and the PC5-RRC connection may refer to a logical connection of a pair between a source ID of the first terminal and a destination ID of the second terminal. The first terminal may send data (e.g., side-uplink data) to the second terminal. When using the broadcast scheme, the first terminal may transmit data to all terminals. When using the multicast scheme, the first terminal may transmit data to a group (e.g., a multicast group) composed of a plurality of terminals.

When the unicast scheme is used, the second terminal may transmit feedback information (e.g., acknowledgement (ACK) or Negative ACK (NACK)) to the first terminal in response to data received from the first terminal. In the following exemplary embodiments, the feedback information may be referred to as "HARQ-ACK", "feedback signal", "physical side uplink feedback channel (PSFCH) signal", or the like. When receiving the ACK from the second terminal, the first terminal may determine that the data has been successfully received at the second terminal. When receiving the NACK from the second terminal, the first terminal may determine that the second terminal fails to receive the data. In this case, the first terminal may transmit additional information to the second terminal based on the HARQ scheme. Or the first terminal may increase the probability of reception of the data at the second terminal by retransmitting the same data to the second terminal.

When the broadcasting scheme is used, a procedure for transmitting feedback information for data may not be performed. For example, the system information may be transmitted in a broadcast scheme, and the terminal may not transmit feedback information of the system information to the base station. Thus, the base station may not be able to determine whether the system information has been successfully received at the terminal. To solve this problem, the base station may periodically broadcast system information.

When the multicast scheme is used, a procedure for transmitting feedback information for data may not be performed. For example, necessary information may be periodically transmitted in a multicast scheme without a procedure of transmitting feedback information. However, when candidates of terminals participating in communication based on the multicast scheme and/or the number of terminals participating therein are limited, and data transmitted in the multicast scheme is data (e.g., delay-sensitive data) that should be received within a preconfigured time, it may also be necessary to transmit feedback information in multicast-side uplink communication. Multicast side-link communications may refer to side-link communications performed in a multicast scheme. When the feedback information transmission process is performed in the multicast-side uplink communication, data can be efficiently and reliably transmitted and received.

In multicast-side uplink communication, two HARQ-ACK feedback schemes (i.e., transmission procedures of feedback information) may be supported. When the number of receiving terminals in the side-uplink group is large and service scenario 1 is supported, some receiving terminals belonging to a specific range within the side-uplink group may transmit NACK through PSFCH when data reception fails. The scheme may be multicast HARQ-ACK feedback option 1. In service scenario 1, some receiving terminals belonging to a specific range may be allowed to try to perform reception instead of all receiving terminals in the side-uplink group. The service scenario 1 may be an extended sensor scenario in which some receiving terminals belonging to a specific range need to receive the same sensor information from the transmitting terminal. In an exemplary embodiment, a transmitting terminal may refer to a terminal that transmits data, and a receiving terminal may refer to a terminal that receives data.

When the number of receiving terminals in the side-uplink group is limited and service scenario 2 is supported, each of all receiving terminals belonging to the side-uplink group may report HARQ-ACKs for data individually through an individual PSFCH. The scheme may be multicast HARQ-ACK feedback option 2. In service scenario 2, since PSFCH resources are sufficient, the transmitting terminal can perform monitoring of HARQ-ACK feedback of all receiving terminals belonging to the side uplink group, and can guarantee data reception at all receiving terminals belonging to the side uplink group. Whether the ACK/NACK feedback procedure is applied to each of all transmission schemes may be statically or semi-statically configured through system information and UE-specific RRC signaling, and its dynamic configuration may also be implemented through control information.

In side-uplink communications, ACK/NACK feedback information may be transmitted on PSFCH. PSFCH may be a channel used by the sidelink receiving terminal to report ACK/NACK information depending on whether the PSSCH was successfully received by the sidelink transmitting terminal. The resource region for PSFCH transmissions may be configured within a particular resource pool.

Referring to fig. 9, a terminal may transmit PSFCH in a slot #n+12, which is a slot capable of transmitting PSFCH after a previously set sl-MINTIMEGAPPSFCH (e.g., 3 slots) from the time (e.g., slot) when the PSSCH is received.

For example PSFCH may be configured to have a periodicity of 1,2, or 4 logical time slots. Referring to fig. 10, PSFCH may repeat transmission on two OFDM symbols in a slot in which PSFCH transmission is possible. The first of the two OFDM symbols of transmission PSFCH may be used for AGC purposes to adjust PSFCH the received power level.

In the corresponding symbol PSFCH may be transmitted within a frequency resource region preconfigured with system information. In this case, the frequency resource region for PSFCH transmissions may be signaled in the form of a bitmap of the corresponding resource pool. The receiving terminal may implicitly select a frequency resource region in which to transmit PSFCH based on the slot index of the receiving PSSCH and the subchannel index of the slots and subchannels. Further, an index of PSFCH resources for transmission PSFCH may be implicitly selected from PSFCH resources multiplexed in a Resource Block (RB) using cyclic shifts of PSFCH sequences within a frequency resource region based on a physical layer source ID and a member ID. In this case, the member ID may be used only in the above-described multicast HARQ ACK/NACK feedback option 2, and in other cases, the member ID may be set to 0. The transmission time PSFCH may be determined as the first slot of PSFCH in which transmission can occur after a predetermined time (i.e., sl-MINTIMEGAPPSFCH) from the reception time of the corresponding PSSCH. The sl-MINTIMEGAPPSFCH may be preset to 2 slots or 3 slots in consideration of the time required to process the received PSSCH and the time required to prepare ACK/NACK information according to whether the PSSCH is successfully received.

Further, the data reliability at the receiving terminal can be improved by appropriately adjusting the transmission power of the transmitting terminal according to the transmission environment. Interference to other terminals can be mitigated by appropriately adjusting the transmit power of the transmitting terminal. Energy efficiency can be improved by reducing unnecessary transmission power. The power control scheme may be classified into an open loop power control scheme and a closed loop power control scheme. In an open loop power control scheme, a transmitting terminal may determine a transmission power in consideration of configuration, measurement environment, and the like. In a closed loop power control scheme, a transmitting terminal may determine a transmit power based on Transmit Power Control (TPC) commands received from a receiving terminal.

It may be difficult to predict the received signal strength at the receiving terminal for various reasons including multipath fading channels, interference, etc. Accordingly, the receiving terminal can adjust a received power level (e.g., a received power range) by performing an Automatic Gain Control (AGC) operation to prevent quantization errors of a received signal and maintain an appropriate received power. In a communication system, a terminal may perform an AGC operation using a reference signal received from a base station. However, in side-link communications (e.g., V2X communications), the reference signal may not be transmitted from the base station. That is, in the side uplink communication, communication between terminals can be performed without a base station. Therefore, it may be difficult to perform AGC operation in side-uplink communication. In the side uplink communication, a transmitting terminal may first transmit a signal (e.g., a reference signal) to a receiving terminal before transmitting data, and the receiving terminal may adjust a reception power range (e.g., a reception power level) by performing an AGC operation based on the signal received from the transmitting terminal. Thereafter, the transmitting terminal may transmit the side uplink data to the receiving terminal. The signal used for the AGC operation may be a signal copied from a signal to be transmitted later, or a signal preconfigured between terminals.

The period of time required for ACG operation may be 15 mus. When a subcarrier spacing of 15kHz is used in an NR system, a period (e.g., length) of one symbol (e.g., OFDM symbol) may be 66.7 μs. When a subcarrier spacing of 30kHz is used in an NR system, a period of one symbol (e.g., an OFDM symbol) may be 33.3 μs. In the following exemplary embodiments, a symbol may refer to an OFDM symbol. That is, the period of one symbol may be twice or more of the period required for the ACG operation.

For side-link communications, it may be desirable to transmit a data channel for data transmission and a control channel including scheduling information for data resource allocation. In sidelink communications, the data channel may be a Physical Sidelink Shared Channel (PSSCH) and the control channel may be a Physical Sidelink Control Channel (PSCCH). The data channels and control channels may be multiplexed in the resource domain (e.g., time and frequency resource domain).

Referring to fig. 10, side-uplink communications may support option 1A, option 1B, option 2, and option 3. When option 1A and/or option 1B are supported, the control channel and the data channel may be multiplexed in the time domain. When option 2 is supported, the control channel and the data channel may be multiplexed in the frequency domain. When option 3 is supported, the control channel and the data channel may be multiplexed in the time domain and the frequency domain. The side-uplink communication may support option 3 basically.

In side-link communications (e.g., NR-V2X side-link communications), a basic unit of resource configuration may be a subchannel. The sub-channels may be defined using time resources and frequency resources. For example, a subchannel may be composed of a plurality of symbols (e.g., OFDM symbols) in the time domain, and may be composed of a plurality of Resource Blocks (RBs) in the frequency domain. The subchannels may be referred to as RB sets. In the sub-channel, the data channel and the control channel may be multiplexed based on option 3.

In side-link communications (e.g., NR-V2X side-link communications), transmission resources may be allocated based on mode 1 or mode 2. When mode 1 is used, the base station may allocate side uplink resources for data transmission in the resource pool to the transmitting terminal, and the transmitting terminal may transmit data to the receiving terminal using the side uplink resources allocated by the base station. Here, the transmitting terminal may be a terminal that transmits data in side uplink communication, and the receiving terminal may be a terminal that receives data in side uplink communication.

When mode 2 is used, the transmitting terminal may autonomously select side uplink resources to be used for data transmission by performing a resource sensing operation and/or a resource selection operation within the resource pool. The base station may configure the terminal with a resource pool for mode 1 and a resource pool for mode 2. The resource pool for mode 1 may be configured independently of the resource pool for mode 2. Or a common resource pool may be configured for mode 1 and mode 2.

When mode 1 is used, the base station may schedule resources for side uplink data transmission to the transmitting terminal, and the transmitting terminal may transmit side uplink data to the receiving terminal by using the resources scheduled by the base station. Accordingly, resource collision between terminals can be prevented. When mode 2 is used, the transmitting terminal may select an arbitrary resource by performing a resource sensing operation and/or a resource selecting operation, and may transmit side uplink data by using the selected arbitrary resource. Since the above-described process is performed based on the respective resource sensing operation and/or the resource selecting operation of each transmitting terminal, a collision may occur between the selected resources.

Therefore, even when the resource allocation pattern 2 is used, a terminal (i.e., a coordinating terminal) which coordinates resources for data transmission and reception between terminals and transmits and receives information (i.e., resource coordination information) on the coordinated resources to a terminal (i.e., a coordinated terminal) which needs to perform data transmission and reception can be configured similarly to the base station of the resource allocation pattern 1. Since the terminal performs data transmission and reception operations within the coordinated resources, occurrence of collision between the resources can be prevented and performance can be improved accordingly. Furthermore, energy efficiency may be improved by the terminal performing sensing and selecting operations within limited resources.

Hereinafter, a method for transmitting resource coordination information in side-uplink communication and an apparatus therefor will be described. Even when a method (e.g., transmission or reception of a signal) to be performed at a first communication node among the communication nodes is described, a corresponding second communication node can perform a method (e.g., reception or transmission of a signal) corresponding to the method performed at the first communication node. That is, when describing the operation of the transmitting terminal, the corresponding receiving terminal may perform an operation corresponding to the operation of the transmitting terminal. In contrast, when describing the operation of the receiving terminal, the corresponding transmitting terminal may perform an operation corresponding to the operation of the receiving terminal.

Resource coordination information configuration and transmission scheme

The resource coordination information and the transmission scheme of the resource coordination information for data transmission and reception between terminals may be classified into two schemes. One is a scheme (i.e., scheme 1) that provides information about candidate resources to assist in the operation of selecting resources to be actually used for data transmission and reception, and the other is a scheme (e.g., scheme 2) that provides information about collisions predicted to occur or to potentially occur in resources selected to be actually used for data transmission and reception.

In scheme 1, a specific terminal (hereinafter referred to as "UE-a") may transmit information (i.e., resource coordination information) about candidate resources for assisting a resource selection operation to another specific terminal (hereinafter referred to as "UE-B"). The UE-B may utilize information about the candidate resources for resource selection. In this case, the information on the candidate resource may be information on a preferred resource or information on a non-preferred resource. When providing information on the preferred resources, it is preferable that the UE-B preferentially selects candidate resources to be used for data transmission from among the preferred resources indicated by the corresponding information. When providing information on non-preferred resources, it is preferable that the UE-B preferentially excludes the non-preferred resources indicated by the corresponding information when selecting candidate resources.

In scheme 2, when a specific terminal (hereinafter referred to as "UE-a") predicts that a collision will occur in resources selected for data transmission and reception by the specific terminal (hereinafter referred to as "UE-B") through SCI monitoring, the UE-a may provide information (i.e., resource coordination information) about the predicted collision to the UE-B. In this case, the UE-B receiving the corresponding information may preferably avoid the predicted collision (i.e., resource reselection) by selecting another resource instead of the resource predicted to have the collision.

Different criteria for selecting UE-a and UE-B for each scheme may be applied. As an example, UE-a may be a terminal that receives data transmitted from UE-B. Further, one or more of UE-A or UE-B may be configured. In the mode 2 side uplink communication, whether scheme 1 is supported and whether scheme 2 is supported may be preconfigured by system information or the like, and may be configured for each resource pool. When scheme 1 is used, a scheme in which resource coordination information is transmitted through an explicit request or a scheme in which resource coordination information is transmitted according to a specific condition other than an explicit request may be configured. Further, it is possible to configure whether the resource coordination information to be transmitted is information on a preferable resource or information on a non-preferable resource. Furthermore, combinations of the above schemes may be configured. For example, in the case of resource coordination information transmission based on an explicit request, only information on a preferred resource may be configured to be transmitted, only information on a non-preferred resource may be configured to be transmitted, or one of information on a preferred resource or information on a non-preferred resource may be configured to be transmitted. Further, information on whether each scheme is supportable for each terminal may be transmitted through UE-specific RRC signaling or PC5-RRC signaling, and may be configured for each resource pool.

In case of scheme 1, the UE-B may receive resource coordination information on preferred resources for data transmission (hereinafter, referred to as "preferred resources") or non-preferred resources for data transmission (hereinafter, referred to as "non-preferred resources") from the UE-a, and utilize the received resource coordination information in a resource (re) selection process. Accordingly, a method for accurately transmitting resource coordination information is required. The resource coordination information may be transmitted using SCI or MAC Control Element (CE), or may be transmitted using both SCI and MAC CE. The transmission scheme of the resource coordination information may be configured for each resource pool through system information, UE-specific RRC signaling, PC5-RRC signaling, or another MAC CE.

When the SCI is used to transmit the resource coordination information, the first level SCI or the second level SCI, or both the first level SCI and the second level SCI may be used to transmit the resource coordination information. The first stage SCI may be transmitted on the PSCCH and the second stage SCI or MAC CE may be transmitted on the PSSCH.

When resource coordination information is transmitted using both SCI and MAC CE, whether to transmit the resource coordination information through SCI and/or MAC CE may be dynamically determined according to the type of the resource coordination information (i.e., preferred resource information or non-preferred resource information) or the size of the resource coordination information. Or the entire resource coordination information may be transmitted redundantly through both SCI and MAC CE. Or the entire resource coordination information may be transmitted through the divided SCI and MAC CE. More specifically, a part of the resource coordination information may be transmitted through the SCI, and the remaining part of the resource coordination information may be transmitted through the MAC CE. In this case, a criterion for determining which container in the SCI and/or MAC CE is to be used for transmitting the resource coordination information may be preconfigured. When determining whether the resource coordination information is transmitted through the SCI or the MAC CE according to the type of the resource coordination information, the type of the resource coordination information may be previously configured to the terminal through system information, UE-specific RRC signaling, or PC5-RRC signaling. The type of the resource coordination information may be transmitted in the form of a 1-bit indicator included in the resource coordination information.

When a preferred resource or a non-preferred resource is selected in scheme 1, the UE-a may select a candidate resource for resource coordination information based on a Received Signal Received Power (RSRP) measured through a sensing procedure.

When the UE-a provides information about the preferred resources, the UE-a may exclude from the preferred resources whose RSRP is measured to be higher than the priority-based preset RSRP threshold. If the number of resources selected based on the preset RSRP threshold does not meet the specific criteria of the preferred resources to be provided, the UE-a may increase the RSRP threshold and then perform the procedure for selecting the preferred resources again. Until the number of selected resources meets a specific criterion of preferred resources to be provided, the UE-a may continuously increase the RSRP threshold and repeatedly perform the procedure for selecting the preferred resources. Or since the resource coordination information is used as auxiliary information for resource selection of the UE-B, the number of selected preferred resources may not necessarily satisfy a specific criterion. Thus, the UE-a may perform a procedure for selecting preferred resources while increasing the RSRP threshold only to a predetermined RSRP upper limit.

Even when the UE-a provides information about non-preferred resources, the UE-a may select non-preferred resources based on RSRP measurement results. In this case, the UE-a may select a resource whose RSRP is measured to be higher than a preset RSRP threshold as a non-preferred resource, unlike the case of selecting a preferred resource. In this case, the UE-a may repeatedly perform the process of selecting non-preferred resources while lowering the RSRP threshold until the number of selected non-preferred resources satisfies a specific criterion of non-preferred resources to be provided. Or the UE-a may perform a procedure for selecting non-preferred resources while lowering the RSRP threshold to a predetermined RSPR lower limit.

In existing side-uplink scheduling schemes, up to three resources may be scheduled or reserved by a combination of time-domain slot index information (i.e., time-domain resource indicator value TRIV) and frequency-domain subchannel index information (e.g., frequency resource indicator value FRIV) according to a configuration. In this case, the number of resources that can be scheduled and reserved through TRIV/FRIV combinations can be configured to the terminal through system information, UE-specific RRC signaling, or PC5-RRC signaling, so that signaling for as many resources as possible is possible. Or the number of resources that can be scheduled and reserved by TRIV/FRIV combinations can be fixed to a maximum of 3. Meanwhile, information about the resource reservation period may be additionally signaled in addition to the TRIV/FRIV combination. Thus, in order to provide resource coordination information, a scheme that extends an existing side-uplink scheduling scheme by N times may be used. For example, the number of resources that may be provided by the resource coordination information may be at most n×3.

In the existing TRIV/FRIV combination-based scheduling scheme, since the slot index and the starting subchannel index of the first resource are configured using the index and the subchannel index of the slot receiving the PSCCH including the corresponding scheduling information, they are not separately signaled. However, separate signaling of the slot index and the subchannel index of the first resource may be required for the resource coordination information. That is, signaling of the slot index (or slot offset) and starting subchannel index of the first resource may be required for each of the N TRIV/FRIV combinations. In this case, the time domain resource information and the frequency domain resource information of the first resource of each of the N combinations may be signaled separately or signaled in combination.

Referring to fig. 11, information about the N TRIV/FRIV combinations may be signaled after being ordered in time order of their first resources within a period for signaling. The resources signaled by the N TRIV/FRIV combinations may preferably be selected to not overlap each other.

When separate signaling is used, time domain resource information and frequency domain resource information of each of N first resources #0, #1, # …, and #n-1 may be signaled. The signaling of time domain resource information (i.e., the index of the first slot or slot offset) may be limited to the time resources located in the front of the target period from which the preferred or non-preferred resources are selected. However, since signaling of frequency domain resource information (i.e., index of starting subchannel or subchannel offset) requires signaling over the entire frequency domain resource, without such limitation, signaling overhead may be relatively large. Therefore, the scope of signaling of the frequency domain resource information may also be limited. The signaling ranges of the time domain resource information and the frequency domain resource information may be preconfigured or predefined in the terminal through system information, UE-specific RRC signaling, or PC5-RRC signaling. In this case, the signaling ranges of the time domain resource information and the frequency domain resource information may be differently configured according to the container for transmitting the resource coordination information. In particular, when the resource coordination information is transmitted through both SCI and MAC CE, since the same information is transmitted through both SCI and MAC-CE, the signaling range can be configured to be smaller considering that SCI has a relatively small number of bits. On the other hand, since a relatively large number of bits are available when resource coordination information is transmitted only through the MAC CE, the signaling range may be configured to be larger. Or the frequency domain resource information may not be separately signaled. In this case, since the information on the starting subchannel index of the first resource cannot be known, it is possible for signaling of resources smaller than the maximum number of resources that can be scheduled and reserved using TRIV/FRIV combinations. That is, when scheduling and reserving up to M resources is possible, M-1 resources may be signaled.

As another method for separate signaling, time domain resource information and frequency domain resource information for resource #0 among the first N resources #0, #1, …, and #n-1 may be signaled, and time domain resource information for resources subsequent to resource #0 may be signaled as an offset with respect to resource # 0. As described above, when the first resources of the N TRIV/FRIV combinations are ordered in the order of early time, the time domain resource information of the first resource for the remaining N-1 resources can be signaled by applying a "+" offset based on the time domain resource information of resource # 0. When simultaneous resource selection is allowed, an offset of "0" may also be included as time domain resource information. The frequency domain resource information of the first resource of the remaining N-1 resources may be signaled as a "+/-" offset including "0". As another method of signaling of the frequency domain resource information, a method of using only "+" offset including "0" and using modulo operation of the total number of subchannels and the offset may be used. In this case, the ranges of the time domain offset and the frequency domain offset may be preconfigured by system information, UE-specific RRC signaling, or PC5-RRC signaling. The time domain resource information and the frequency domain resource information of the resource #0 may be signaled as offsets like the other first resources #1, #2, …, and #n-1. In this case, the time domain reference and the frequency domain reference of the resource #0 may be separately required.

As another method of separate signaling, offset-based signaling of time domain resource information and frequency domain resource information in a wider range may be applied to only the first resource #0 of the N first resources #0, #1, # …, and #n-1, and offset-based signaling of time domain resource information and frequency domain resource information in a limited range may be applied to the remaining first resources #1, #2, …, and #n-1. Even in this case, the time domain reference and the frequency domain reference of the resource #0 may be separately required.

Or time domain resource information and frequency domain resource information of resource #0 of the first N resources #0, #1, …, and #n-1 may be signaled and the subsequent resources may be signaled using TRIV/FRIV combination in a chain form.

Referring to fig. 12, time domain resource information and frequency domain resource information of resource #0 corresponding to a first resource of a first combination of N TRIV/FRIV combinations may be separately signaled, and a last resource of the first TRIV/FRIV combination may be signaled as a first resource of a second TRIV/FRIV combination. When such signaling is used, since only signaling of time domain resource information and frequency domain resource information of resources corresponding to resource #0 of the first N resources #0, #1, …, and #n-1 is required, signaling overhead can be reduced.

In the above procedure, a reference slot for time domain resource information of the N first resources #0, #1, # …, and #n-1 or a reference slot for time domain resource information of the first resource #0 of the N first resources may be required. When time domain resource information is provided as a slot index or slot offset, the reference slot may be a slot that is a reference for the information. The reference time slot may be configured as a time slot in which the resource coordination information is transmitted, and the information about the reference time slot may be transmitted through the resource coordination information separate from the time domain resource information.

When the reference slot is configured as a slot for transmitting resource coordination information, the reference slot may be time domain resource information of resource #0, which is a first one of N first resources #0, #1, # …, and #n-1, and the time domain resource information of the remaining first resources #1 to #n-1 may be expressed as a slot offset with respect to the reference slot.

When information on the reference slot is separately transmitted through the resource coordination information, the corresponding information may be composed of a combination of a frame number such as SFN or DFN and an index of a slot within the corresponding frame. Further, reference subchannel indexes for frequency domain resource information of N first resources #0, #1, …, and #n-1 or reference subchannel indexes for frequency domain resource information of the first resource #0 of the N first resources may be required. In this case, the reference subchannel index may be a subchannel index #0 within the corresponding resource pool, or may be a first subchannel index (i.e., the lowest subchannel index) of the frequency resources transmitting the resource coordination information. Or separate from the frequency domain resource information, a particular subchannel index within the corresponding resource pool may be indicated as a reference subchannel index by the resource coordination information.

When configuring resource coordination information based on TRIV/FRIV combinations, if the number of subchannels indicated by FRIV (e.g., N _sub) is greater than the number of subchannels required for data transmission (e.g., N _sub,req), then all N _sub,req consecutive subchannels less than N _sub may be selected as separate candidate resources for data transmission. For example, if N _sub,req = 3 and the starting subchannel index = 1 and N _sub = 5 are signaled by FRIV, then either subchannel {1,2,3}, subchannel {2,3,4} or subchannel {3,4,5} may be indicated as separate candidate resources for data transmission.

As described above, even when the resource coordination information can be transmitted in N TRIV/FRIV combinations, the number of TRIV/FRIV combinations that can actually be signaled may be smaller than N. However, when the size of the entire resource coordination information varies according to the number of TRIV/FRIV combinations that can be actually signaled, the reception complexity of a terminal receiving it may increase. Thus, the size of the entire resource coordination information can be kept constant regardless of the number of actual signaled TRIV/FRIV combinations, and information about the number of actual signaled TRIV/FRIV combinations (+.N) can be added to the corresponding resource coordination information separately.

Priority of resource coordination information transmission

The resource coordination information in scheme 1 may be sent from UE-a to UE-B according to an explicit request by UE-B or certain predefined conditions. When the resource coordination information is transmitted according to an explicit request of the UE-B, the request message of the UE-B may be delivered through the first level SCI, the second level SCI, or the MAC CE. The same request message may be sent through both the second level SCI and the MAC CE, or through a combination of the second level SCI and the MAC CE. In this case, which container is passed for transmitting the request message may be configured for each resource pool through system information, UE-specific RRC signaling, PC5-RRC signaling, and/or another MAC CE.

When the request message is transmitted through both the second-stage SCI and the MAC CE, the same information may be transmitted through both the second-stage SCI and the MAC CE, and a 1-bit indicator for identifying whether the corresponding information is the request message or the resource coordination information may be included in the corresponding SCI and/or the MAC CE. Further, when the request message is transmitted through a combination of the second stage SCI and the MAC CE, a 1-bit indicator for requesting resource coordination information may be transmitted through the corresponding SCI, and additional request-related information may be transmitted through the MAC CE. The request message may include a priority value for PSCCH and PSSCH transmissions, the number of sub-channels, and resource reservation period information for periodic transmissions, whether or not it is transmitted through the second level SCI and/or MAC CE. In this case, the priority value may be referred to in the resource coordination information selection process of the UE-a. In addition, when the UE-A transmits the resource coordination information to the UE-B, it may be applied as a priority for the transmission of the resource coordination information. Further, the request message may include information on a start time and an end time, or information on only an end time for configuring a period in which preferred/non-preferred resources for the resource coordination information are selected (i.e., a resource selection period). The UE-a may configure a resource selection period for the resource coordination information based on the corresponding information, and the corresponding information may be composed of a specific frame number (i.e., SFN or DFN) and a slot index within the corresponding specific frame. Further, the request message may further include information indicating whether the requested resource coordination information is information about a preferred resource or information about a non-preferred resource. When the resource coordination information is transmitted according to a specific condition instead of the request message, the above information may be preconfigured by system information, UE-specific RRC signaling, and/or PC5-RRC signaling.

As described above, the resource coordination information and the request message (e.g., whether they are to be transmitted by only the MAC CE or by both the MAC CE and the second level SCI) may be transmitted by which container is configured for each resource pool by system information, UE-specific RRC signaling, PC5-RRC signaling, or another MAC CE. In this case, in terms of signaling overhead efficiency, it may be preferable to apply the corresponding configuration to both the resource coordination information and the request message instead of applying the corresponding configuration to the resource coordination information or the request message, respectively. That is, when configured to be transmitted only through the MAC CE, both the resource coordination information and the request message may be transmitted only through the MAC CE, and when configured to be transmitted through both the second-stage SCI and the MAC CE, both the resource coordination information and the request message may be transmitted through both the second-stage SCI and the MAC CE.

As described above, when the resource coordination information is transmitted according to an explicit request message of the UE-B or a specific condition, the priority of the resource coordination information may be set through system information, UE-specific RRC signaling, PC5-RRC signaling, or the like. When the corresponding priority is not set, if the resource coordination information is transmitted through the request message, the priority (i.e., priority value) included in the request message or the priority of the request message may be set as the priority of the resource coordination information. When the corresponding priority is not set, if the resource coordination information is transmitted under a specific condition, the terminal may set the priority of the resource coordination information according to an implementation manner. When the resource coordination information is multiplexed with other data for transmission, a higher priority may be applied by comparing the priority of the resource coordination information with the priority of the data. In the above procedure, the priority is determined according to the priority value corresponding thereto, and a higher priority value means a lower priority (i.e., a highest priority value means a lowest priority). Based on the priority set as described above, the terminal can determine whether to transmit the corresponding resource coordination information through an existing priority comparison procedure between the uplink and the side link or an existing priority comparison procedure between the LTE side link and the NR side link. When the resource coordination information is received, a priority of the corresponding resource coordination information may be determined based on priority information included in the SCI for scheduling the PSSCH including the corresponding resource coordination information.

When UE-a transmits resource coordination information to UE-B, a source ID and a destination ID for transmitting the resource coordination information may be required. When the side-uplink communication between UE-a and UE-B is a unicast communication or a managed multicast communication in which the transmitting terminal knows information about the receiving terminal, and the transmission of the resource coordination information of UE-a is a transmission according to an explicit request of UE-B, UE-a may transmit the resource coordination information using a source ID and a destination ID used in the transmission of the request message of UE-B. That is, the source ID and the destination ID of the request message of the UE-B may be applied as the destination ID and the source ID of the resource coordination information transmission of the UE-a, respectively. Further, when the request message for the resource coordination information is a request for a terminal other than the UE-B, or the side-link communication between the UE-a and the UE-B is not unicast or managed multicast communication, it may be preferable to include a source ID and a destination ID of the corresponding terminal in the request message. When the resource coordination information is transmitted according to a specific condition, it may be preferable that the source ID and the destination ID are preconfigured.

Feedback/retransmission of resource coordination information

After the UE-B transmits the request message for the resource coordination information, the UE-B may receive the corresponding resource coordination information within a predetermined time (e.g., T _ci,1). If the UE-B fails to receive the resource coordination information within a predetermined time, or if the request message is transmitted on the PSSCH (e.g., if the request message is transmitted using a MAC CE), but a NACK for the PSSCH is fed back to the UE-B (i.e., when HARQ ACK/NACK feedback is enabled), the UE-B may retransmit the request message in consideration of a maximum requestable time (e.g., T _bound,1) according to a data transmission time (e.g., a Packet Delay Budget (PDB)) or the like. Further, when the UE-B fails to receive the resource coordination information within a predetermined time (e.g., if transmission of the PSSCH including the resource coordination information is recognized through the SCI but decoding of the resource coordination information fails), if HARQ ACK/NACK feedback is enabled, the UE-B may transmit NACK feedback for the PSSCH (i.e., the resource coordination information) instead of the retransmission request message.

On the other hand, the UE-a may need to transmit the requested resource coordination information within a predetermined time (e.g., T _ci,2) after receiving the request message for the resource coordination information. The UE-a may retransmit the resource coordination information when the UE-a re-receives the request message or when the resource coordination information is transmitted on the PSSCH (e.g., when the resource coordination information is transmitted using the MAC CE) but NACK feedback for the PSSCH (i.e., the resource coordination information) is received (i.e., when HARQ ACK/NACK feedback is enabled). even when the UE-a receives NACK feedback, if the retransmission time of the resource coordination information is outside the maximum transmittable time (e.g., T _bound,2), the UE-a may not retransmit the corresponding resource coordination information. In this case, T _ci,1、T_ci,2、T_bound,1 and T _bound,2 may be set differently, and some or all of them (e.g., T _ci,1 and T _ci,2, Or T _bound,1 and T _bound,2) are set to the same value. T _ci,1、T_ci,2、T_bound,1 and T _bound,2 may be configured by system information, UE-specific RRC signaling, or PC5-RRC signaling. Or the corresponding value may be applied as a timer value. For example, the timer for T _ci,₂ may be started after the UE-A receives the request message, and the UE-A may send the resource coordination information before the timer expires. Even when transmission of the resource coordination information is performed based on a specific condition, the predetermined number of times or the timer can be equally applied to transmission/reception and retransmission of the resource coordination information. In all the above cases, transmission resources for transmitting or retransmitting the resource coordination information should be ensured. If the transmission resources are not guaranteed within the maximum transmissible time, the UE-a may cancel the transmission of the resource coordination information.

Scheme 2 is a scheme in which UE-B receives information about a predicted collision or potential collision from UE-a as resource coordination information before transmitting data, and performs a resource reselection operation to avoid resources for which a collision is predicted. Therefore, in scheme 2, it is preferable that the procedure for receiving the resource coordination information is not complicated. Accordingly, the resource coordination information according to scheme 2 may preferably be transmitted using PSFCH for the conventional HARQ ACK/NACK transmission. Unlike PSFCH (hereinafter referred to as "AN-PSFCH") including HARQ ACK/NACK for PSSCH, which has been described with reference to fig. 9, PSFCH (hereinafter referred to as "CI-PSFCH'") for transmitting resource coordination information (hereinafter referred to as collision indication) according to scheme 2 can be used for a resource reselection operation for transmitting PSSCH. Therefore PSFCH for transmitting the collision indication according to scheme 2 should be transmitted before the UE-B transmits the PSSCH.

Accordingly, exemplary embodiments of the present disclosure propose a time of transmitting CI-PSFCH before the UE-B transmits PSSCH, a resource selection method for transmitting CI-PSF CH, and a transmission method of CI-PSFCH.

CI-PSFCH transmit time determination

As described above, unlike AN-PSFCH, since CI-PSFCH should be transmitted before UE-B transmits PSSCH, AN appropriate time for transmitting CI-PSFCH needs to be configured.

To generate the collision indication, the UE-A may monitor a plurality of SCIs including the SCI of the UE-B. When a resource (or sub-channel) predicted to be used by UE-B is identified by monitoring to partially or completely overlap with a resource (or sub-channel) predicted to be used by another terminal (e.g., UE-C), UE-a may predict a collision of the resource predicted to be used by UE-B and send its collision indication to UE-B. In this case, the UE-a may measure RSRP of the corresponding resource (i.e., the resource predicted to be used by the UE-B), and when the measured RSRP is greater than an RSRP threshold according to priority information of the UE-B, priority information in SCI of another terminal (e.g., UE-C), or a preset RSRP threshold, the UE-a may predict collision of the corresponding resource. As another method, the UE-a may predict a collision of corresponding resources when the RSRP measured for the corresponding resources (i.e., the resources predicted to be used by the UE-B) is within a preset RSRP range. As another approach, UE-A may predict a collision of corresponding resources when the distance between UE-B and UE-C, determined based on their SCIs, is within a predetermined distance. As another method, various criteria for determining resource collision may be predefined, and at least some of the criteria may be configured to the terminal through system information or UE-specific RRC signaling, and may be configured for each resource pool.

As described above, the transmission time of the CI-PSFCH for transmitting information about the predicted collision may be configured based on a slot in which the SCI for predicting the collision (i.e., the SCI transmitted by the UE-B) is transmitted, or a slot in which the PSSCH predicted that the corresponding collision will occur is to be transmitted. Earlier signaling may be possible when the transmit time of CI-PSFCH is determined based on the time slot in which the SCI used to predict the collision is transmitted. In general, since a plurality of PSSCH resources can be reserved by one SCI (hereinafter, referred to as a "first SCI" for convenience), a collision predicted for a PSSCH resource to be used later can be more quickly signaled. However, the collision may be determined not only by monitoring the first SCI but also by monitoring other SCIs (hereinafter referred to as "second SCI"). Therefore, when resource coordination information (i.e., information about a predicted collision) is signaled at a time determined based on the first SCI, prediction information about a collision caused by the second SCI transmitted after the corresponding time cannot be provided, and thus it may be difficult to expect a large performance improvement effect. Furthermore, when the first SCI signals a plurality of reserved resources, it may be necessary to additionally signal information about in which of the plurality of resources the collision will occur, which may increase signaling overhead. On the other hand, when the time to transmit the resource coordination information is determined based on the time slot in which the PSSCH predicted to collide is to be transmitted, the signaling delay time may increase. However, better performance can be expected since collisions can be predicted based on monitoring results for a greater number of second SCIs. Further, even when the first SCI signals a plurality of resources, since the resource coordination information is signaled at a time determined based on the location of the resource in which the actual collision is predicted, it may not be necessary to separately signal information as to in which resource the collision is predicted to occur.

As described above, the advantages and disadvantages may be determined depending on whether the transmission time of the CI-PSFCH is based on the time slot in which the SCI for predicting the collision is transmitted or the time slot in which the PSSCH in which the collision is predicted to occur is to be transmitted. Therefore, which of the two schemes is selected for each resource pool configuration according to various system conditions may be through system information, UE-specific RRC signaling, MAC CE, and the like.

Hereinafter, exemplary embodiments of the present disclosure propose a method for determining a transmission time of CI-PSFCH based on a slot in which a PSSCH predicted to have a collision is to be transmitted. Unlike AN-PSFCH, which transmits after receiving the PSSCH, CI-PSFCH should be transmitted from UE-A to UE-B before UE-B transmits the PSSCH. In this case, it is preferable that the time of transmitting the CI-PSFCH is determined in consideration of the processing time required for the UE-B to receive and process the CI-PSFCH and the processing time required for the UE-B to perform resource reselection according to the received information of the CI-PSFCH. Accordingly, a method is proposed in which a minimum time interval (e.g., T _min) in consideration of the above-described processing time is configured, and the time to transmit CI-PSFCH is determined as the nearest (i.e., latest) slot among slots (i.e., CI-PSFCH transmission slots) that can transmit CI-PSFCH by T _min or more before a slot in which a PSSCH predicted to have a collision is to be transmitted. In this case, the value of T _min may be set through system information, UE-specific RRC signaling, and/or MAC CE.

Referring to fig. 13, it can be assumed that a slot in which a resource reserved for transmission of the PSSCH is located is a slot #k, T _min is set to 3 slots, and a period for the CI-PSFCH transmission slot is set to 4 slots. UE-a may send CI-PSFCH to UE-B in slot # (n+12), which is the nearest (i.e., the latest) slot of the CI-PSFCH transmission slots at slot # (k-T _min) or at a time earlier than slot # (k-T _min). The UE-B may perform CI-PSFCH monitoring in a slot # (n+12) determined based on a slot #k reserved for transmission of the PSSCH. The UE-B may obtain resource coordination information in slot # (n+12) indicating that the transmission of the PSSCH to be performed in slot # k is predicted to collide with the transmission of the PSSCH of another terminal (e.g., UE-C), perform resource reselection based on the resource coordination information, and transmit the PSSCH using another selected resource. In fig. 13, an example of setting T _min =3 has been described. However, it may be preferable that the value of T _min be set to T ₃(＝T_proc,1 ^SL) or more, which is a time that allows re-evaluation to be performed on the resources selected through the sidelink resource selection procedure of release 16 before actual sidelink data transmission is performed using the selected resources. Furthermore, it may be preferable to send CI-PSFCH after T _min,₂, T _min,2 being the processing time required for UE-A to determine the predictive collision after receiving the SCI. In this case, the value of T _min,2 may be equivalently configured as sl-MINTIMEGAPPSFCH (described with reference to fig. 9), sl-MINTIMEGAPPSFCH being a minimum time interval for transmitting HARQ ACK/NACK information for the received PSSCH after the reception of the PSSCH, and defined in the existing release 16 side uplink specification. As another approach, unlike AN-PSFCH, it may not be necessary to determine whether data reception for CI-PSFCH was successful, and thus T _min,2 may be set to T _proc,0 ^SL which is shorter than sl-MINTIMEGAPPSFCH. The resource coordination information in scheme 2 is information about a collision predicted in a slot in which the PSSCH is to be transmitted, and does not even convey information about a subchannel for transmitting the PSSCH in a frequency domain within the corresponding slot. Thus, when performing resource reselection, it may be preferable that the UE-B select resources of slots other than the corresponding slot. More specifically, during the resource reselection, the UE-B may preferably exclude all sub-channels corresponding to the time slots for which the collision is predicted by the resource coordination information from the candidate resources for the resource reselection. When the resource coordination information is transmitted at a time determined based on a slot in which the PSSCH is to be transmitted, it is possible to identify in which reserved resource a collision is predicted even when the SCI reserves a plurality of resources. Thus, upon receiving the resource coordination information, the UE-B may exclude the sub-channels belonging to the slots in which the PSSCH is reserved from the candidate resources for resource reselection. Even in this case, the UE-B may exclude the sub-channels corresponding to the slots including all of its reserved resources and the slots to transmit the PSSCH predicted to have collision from the candidate resources for resource reselection. Or the UE-B may determine that the collision indicated by the received resource coordination information is limited to the sub-channels reserved for transmission of the PSSCH within the corresponding slot (the immediately next reserved resource slot or the slot including all reserved resources), and may exclude only resources overlapping with the corresponding sub-channels from the candidate resources. The above procedure may be configured for each resource pool through system information, UE-specific RRC signaling, PC5 RRC signaling, or MAC CE.

Hereinafter, a method of transmitting CI-PSFCH when determining a time of transmitting CI-PSFCH based on a time slot of transmitting SCI for predicting collision will be described. When CI-PSFCH is transmitted at a time determined based on a time slot in which SCI for predicting collision is transmitted, it may be preferable that UE-B transmits CI-PSFCH after a predetermined processing time has elapsed since the time at which SCI was received. Thus, a minimum time interval (i.e., T _min,2) that takes into account processing time may be configured, and UE-B may transmit CI-PSFCH in the nearest (earliest) one of the slots in which CI-PSFCH may be transmitted at a time after T _min,2 has elapsed. In this case, the value of T _min,2 may be set through system information, UE-specific RRC signaling, or MAC CE.

Referring to fig. 14, it may be assumed that T _min,2 is set to 3 slots and the period of the CI-PSFCH transmission slot is set to 4 slots. When PSCCH including SCI is transmitted in slot #m and collision is predicted in the resources of slot #k reserved by the corresponding SCI, UE-a may transmit CI-PSFCH to UE-B in the nearest (earliest) slot# (n+8) of CI-PSFCH transmit slots at or after the period of time from slot #m to slot# (m+t _min,2). UE-B may perform the monitoring of CI-PSFCH in slot # (n+8). The UE-B may obtain resource coordination information in slot # (n+8) indicating that the transmission of the PSSCH to be performed in slot # k is predicted to collide with the transmission of the PSSCH of another UE (e.g., UE-C), perform resource reselection based on the resource coordination information, and transmit the PSSCH using another selected resource. In fig. 14, an example has been described in which T _min,2 is set to 3. however, the value of T _min,2 may be equivalently configured as sl-MINTIMEGAPPSFCH, which is a minimum period for transmitting HARQ ACK/NACK information for the received PSSCH described with reference to fig. 9. Unlike AN-PSFCH, it may not be necessary to determine whether data reception for CI-PSFCH was successful, so T _min,2 may be set to T _proc,0 ^SL, which is shorter than sl-MINTIMEGAPPSFCH. Furthermore, in order for the UE-B to receive CI-PSFCH and perform resource reselection based on the received CI-PSFCH, it may be preferable to receive CI-PSFCH before at least T _min from time slot k where an actual collision is predicted. In this case, it may be preferable that T _min be set to T ₃(＝T_proc, ^1SL) or more, T ₃ is a time that allows re-evaluation to be performed on the resource selected through the release 16 side uplink resource selection procedure before the side data transmission is actually performed using the selected resource. The resource coordination information in scheme 2 is information about a collision predicted in a slot in which the PSSCH is to be transmitted, and does not even convey information about a subchannel used to transmit the PSSCH in the frequency domain within the corresponding slot. Therefore, when performing resource reselection, it is preferable that the UE-B selects resources of slots other than the corresponding slot. More specifically, during the resource reselection, the UE-B may preferably exclude all sub-channels corresponding to the time slots for which the collision is predicted by the resource coordination information from the candidate resources for the resource reselection. When the SCI reserves a plurality of resources, the resource coordination information may include additional information about in which reserved resources a collision is predicted to occur. In this case, the UE-B may exclude the sub-channels belonging to the reserved resource slots immediately after the slot in which the corresponding resource coordination information is received from the candidate resources for resource reselection. Or the UE-B may exclude sub-channels belonging to the time slot including all its reserved resources from the candidate resources for resource reselection. Or the UE-B may determine that the collision indicated by the received resource coordination information is limited to the sub-channels reserved for transmission of the PSSCH within the corresponding slot (the immediately next reserved resource slot or the slot including all reserved resources), and may exclude only resources overlapping with the corresponding sub-channels from the candidate resources. The above procedure may be configured for each resource pool through system information, UE-specific RRC signaling, PC5 RRC signaling, or MAC CE.

When CI-PSFCH is transmitted as described above, if the transmission period of AN-PSFCH for HARQ ACK/NACK information transmission of PSSCH received in slot #m is configured to be equal to the transmission period of CI-PSFCH, CI-PSFCH and AN-PSFCH can always be transmitted in the same slot. Thus, to avoid this, the transmission period of CI-PSFCH and the transmission period of AN-PSFCH may be configured to be different from each other. Or the transmission period of CI-PSFCH and the transmission period of AN-PSFCH may be configured to be the same and AN offset may be applied between the CI-PSFCH transmission slot and the AN-PSF CH transmission slot. When CI-PSFCH and AN-PSFCH are always transmitted in the same time slot, either CI-PSFCH or AN-PSFCH may be transmitted according to the method for prioritizing between CI-PSFCH and AN-PSFCH described later.

In fig. 13 or 14, in order for the UE-B to select a new resource based on the resource coordination information, it may be preferable to receive the CI-PSFCH before a minimum time interval T _min(≥T₃ from the resource for which a collision is predicted. If the minimum time interval cannot be guaranteed, the UE-A may stop the CI-PSFCH transmission.

Determination of CI-PSFCH transmission resources

As with AN-PSFCH, the transmission resources of CI-PSFCH need to be configured. Accordingly, a method for configuring transmission resources of the CI-PSFCH will be described below.

For example, in case of transmitting AN-PSFCH, a frequency region that can be multiplexed within one RB for transmitting and receiving AN-PSFCH, the number of resource periods and cyclic shift pairs, the number of AN-PSFCH resources capable of multiplexing HARQ ACK/NACK information, and a scrambling ID for sequence hopping of AN-PSFCH may be configured. To reduce signaling overhead, it may be preferable that the transmission period of CI-PSFCH be configured the same as the transmission period of AN-PSFCH, rather than being configured separately. Further, it may be preferable that the number of cyclic shift pairs that can be multiplexed within one RB is not separately set, and the same value as that set for AN-PSFCH is used or is always fixed to one. Similar to the HARQ ACK/NACK information, it may be preferable that the number of CI-PSFCH resources capable of multiplexing collision indication information is also the same as the number of AN-PSFCH or is always fixed to one. It may be preferred that the scrambling ID for the sequence hopping of CI-PSFCH also use the same value as AN-PSFCH or be always fixed to 0. Or when AN-PSFCH and CI-PSFCH are transmitted in the same resource region, the scrambling IDs for sequence hopping of CI-PSFCH may be set separately in order to reduce interference to the AN-PSFCH sequence.

AN-PSFCH transmits in the last two symbols of AN-PSFCH transmission slot and its frequency region can be configured by RB-level bitmap signaling in the corresponding resource pool. Accordingly, CI-PSFCH, which has the same transmission period as AN-PSFCH, can be transmitted in the same slot and the same symbol as AN-PSFCH, and the frequency region of CI-PSFCH can be configured differently from that of AN-PSFCH, thereby reducing signaling overhead. In this case, the frequency domain resources of CI-PSFCH may be implicitly configured as resources other than the frequency region configured for transmitting AN-PSFCH within the corresponding time slot. Or the frequency domain resources of CI-PSFCH may be configured through separate RB-level bitmap signaling in the same manner as in the case of AN-PSFCH.

As described above, in the resource region of the CI-PSFCH configured through such parameter signaling, the transmission time of the CI-PSFCH may be determined based on a slot in which the PSSCH predicted to have a collision is to be transmitted. The resources of CI-PSFCH at this time may be selected based on the index of the slot and the index of the subchannel to which the PSSCH predicted to have a collision is to be transmitted. It may be preferable to set the PSFCH index actually used within the selected CI-PSFCH resources based on the physical layer source ID (i.e., p_id) indicated by the SCI of the UE-B. The ID for the receiving terminal may also be applied when the ID (e.g., member ID (m_id)) for the receiving terminal is additionally configured from a higher layer. When there is no additional configuration for the ID of the receiving terminal, the corresponding value may be fixed to 0. Further, when there are one or more subchannels for transmitting the PSSCH predicted to have collision, it may be preferable that an index of a first subchannel (i.e., a minimum subchannel index) among the one or more subchannels becomes a subchannel index for selecting the CI-PSFCH resource.

The information transmitted and received on the CI-PSFCH may include information indicating that a collision is predicted in the resources of the PSSCH of the UE-B to be transmitted (i.e., collision prediction information). Or the information transmitted and received on the CI-PSFCH may consist of information in which a collision is predicted in the resource of the PSSCH of the UE-B to be transmitted or information in which no collision is predicted in the corresponding resource (i.e., when the information transmitted and received on the CI-PSFCH is information on whether a collision is predicted or not). When only collision prediction information is transmitted/received, only one value in the cyclic shift pair may be used for transmission/reception of CI-PSFCH. When information indicating that a collision is predicted or information that a collision is not predicted is transmitted/received according to circumstances, two values of a cyclic shift pair are available to be allocated to the corresponding information. In this case, whether to transmit/receive collision prediction information or information on whether to predict a collision may be configured through system information or UE-specific RRC signaling.

As another method, information of the priority of data (e.g., PSSCH) to be transmitted by the UE-B and the priority of data (e.g., PSSCH) of another terminal (e.g., UE-C) predicted to collide with the data to be transmitted by the UE-B may be transmitted and received through the CI-PSFCH. For example, the result of comparing the priority of data to be transmitted by the UE-B with the priority of data of another terminal (e.g., UE-C) predicted to collide with the data to be transmitted by the UE-B may be transmitted and received through the CI-PSFCH. That is, the priority of the data of the UE-C may be notified by the CI-PSFCH to be lower than the priority of the data of the UE-B for which the collision is predicted in the corresponding resource, or the priority of the data of the UE-C to be higher than the priority of the data of the UE-B for which the collision is predicted in the corresponding resource. In this case, two values of the cyclic shift pair may be respectively allocated to the two types of information. When the priorities of the data of the two terminals are the same, it may be preconfigured to be indicated by one of two values of the cyclic shift pair. If the priority of the data of UE-C is lower than the priority of the data of UE-B, UE-B may not need to perform resource reselection. That is, the UE-B may perform resource reselection only when the priority of the data of the UE-C is higher than the priority of the data of the UE-B.

Or information about various conflict prediction cases may be notified through the CI-PSFCH. For example, two values of a cyclic shift pair may be allocated to a case where collision occurrence is predicted by a reserved resource of another terminal and a case where collision prediction itself is not performed, respectively. More specifically, since the UE-a cannot perform half duplex problem of sensing a control channel of another terminal when performing another side uplink transmission, a case may occur in which collision prediction itself is not performed.

In the above method, the two values of the cyclic shift pair may correspond to the zeroth and sixth cyclic shifts of the PSFCH sequence, respectively.

As another method, when the transmission time of CI-PSFCH is determined based on the slot of SCI transmitting UE-B for predicting collision (i.e., the case of fig. 14), if SCI reserves a plurality of resources, whether collision is predicted for each of the plurality of reserved resources may be notified through CI-PSFCH. For example, when the SCI reserves two additional resources (hereinafter, first reserved resources and second reserved resources) in addition to the resources reserved for transmitting the PSSCH in the corresponding slot, a collision may be predicted in the first reserved resources or the second reserved resources, or a collision may be predicted in both the first reserved resources and the second reserved resources. In this case, the UE-a may inform information about in which reserved resource a collision is predicted by applying different cyclic shifts. More specifically, the UE-a may transmit CI-PSFCH by using cyclic shift #0 when a collision is predicted in the first reserved resource, cyclic shift #1 when a collision is predicted in the second reserved resource, and cyclic bit #2 when a collision is predicted in both the first reserved resource and the second reserved resource. In the above method, the cyclic shifts #0, #1, and #2 may correspond to the zeroth, fourth, and eighth cyclic shifts of the PSFCH sequence, respectively. The CI-PSFCH may be transmitted by additionally applying another cyclic shift value even in the case that no resource collision is predicted. When a different cyclic shift is not used to inform whether a collision is predicted for each reserved resource, the transmission of resource coordination information through the CI-PSFCH for which of the plurality of reserved resources may be preconfigured by system information or PC5-RRC signaling or the like, or may be predefined by a technical specification. For example, when only one additional reserved resource can be reserved using the SCI, the information transmitted through the CI-PSFCH may be information about the reserved resource, and when two or more additional reserved resources can be reserved using the SCI, the information transmitted through the CI-PSFCH may be information about the earliest reserved resource (e.g., the first reserved resource when the first reserved resource and the second reserved resource exist as described above).

Transmission/reception priority of CI-PSFCH

When transmitting the resource coordination information, the UE-a may dynamically select and transmit the above-described information on whether a collision is predicted, collision prediction information, and information on priority of data for which a collision is predicted, according to circumstances.

For example, different m_id values may be assigned to the above-described collision prediction information (or information on whether a collision is predicted) and information on the priority of the data for which a collision is predicted, and the UE-a may dynamically select the type of information to be transmitted according to the m_id value. In this case, the m_id value corresponding to the different types of information may be preconfigured through system information or UE-specific RRC signaling. In addition to the above information on whether a conflict is predicted (or conflict prediction information) and information on the priority of the data for which a conflict is predicted, different mjd values may be used to classify other types of information. Further, since the resource coordination information is information about resource conflicts between a plurality of terminals (e.g., resource conflicts between UE-B and UE-C), when the resource coordination information is transmitted to some of the plurality of terminals or to only one terminal, which of the corresponding terminals to which the resource coordination information is to be transmitted may be preconfigured (e.g., designated as UE-B) or may be determined in consideration of priorities of data of the plurality of terminals. When multiple CIs-PSFCH are allowed to be transmitted, the resource coordination information may be transmitted to all corresponding multiple terminals (e.g., UE-B and UE-C).

When the UE-A needs to transmit a plurality of CIs PSFCH at the same time, its CI-PSFH transmission method is required. When the UE-A needs to transmit multiple CIs-PSFCH simultaneously, the UE-A may transmit all of the multiple CIs-PSFCH or only some of the multiple CIs-PSFCH. When the UE-a transmits only some CIs-PSFCH, the number of CI-PSFCH that can be transmitted may be configured by system information, UE-specific RRC signaling, or PC5 RRC signaling. If the number of transmittable CIs-PSFCH is preconfigured, the UE-a may transmit as many CIs-PSFCH as the number of configurations. That is, the UE-a may select as many terminals as the number of configurations based on the priority of the data of the plurality of terminals predicted to collide and transmit CI-PSFCH to the selected terminals.

The priority of the CI-PSFCH may be determined according to the priority of the corresponding data, and the priority of the data may be determined based on the SCI including the scheduling information of the data. In this case, the highest priority among priorities of SCIs including scheduling information of a pair of PSSCHs for which collision is predicted may be selected as the priority of CI-PSFCH. Or the priority of SCI that actually transmits collision prediction information may be selected as the priority of CI-PSFCH. Or the priority of CI-PSFCH may be preset to a specific priority, and in this case, the specific priority may be the highest priority. In addition, when the transmission power required to transmit the preset number of CIs-PSFCH exceeds the maximum transmission power of the terminal, the number of CIs-PSFCH actually transmitted may be further limited within a range not exceeding the maximum transmission power of the terminal.

The reception priority needs to be applied even when the UE-B receives CI-PSFCH. Since CI-PSFCH received by the UE-B is information about the data scheduled by the UE-B, the priority of the data scheduled by the UE-B (i.e., the priority included in the SCI of the scheduled data) can be applied to determine the reception priority of CI-PSFCH. In the above procedure, the priority may be determined according to the priority value, and the high priority value represents the low priority (i.e., the highest priority value represents the lowest priority).

When the UE-a transmitting the resource coordination information needs to simultaneously receive the CI-PSFCH from another terminal, simultaneous transmission and reception may or may not be possible depending on the capability of the UE-a. When simultaneous transmission and reception is impossible, the UE-a may selectively perform a transmission or reception operation in consideration of the priority of the CI-PSFCH to be transmitted and the priority of the CI-PSFCH to be received. From the perspective of one terminal, it is necessary to determine a transmission or reception operation by considering CI-PSFCH for transmitting/receiving resource coordination information and AN-PSFCH for transmitting/receiving HARQ ACK/NACK. Hereinafter, the operation of the terminal according to each case will be described.

● CI-PSFCH send and AN-PSFCH send: AN-PSFCH may always have a higher priority than CI-PSFCH. The terminal (e.g., UE-a) may preferentially perform the transmission operation of AN-PSFCH. Or without distinguishing AN-PSFCH from CI-PSFCH, the terminal (e.g., UE-a) may compare the priority of AN-PSFCH to be transmitted with the priority of CI-PSFCH to be transmitted and preferentially transmit PSFCH with higher priority. In this case, the maximum number of transmittable PSFCH may be preconfigured through system information or UE-specific RRC signaling, and may be additionally limited according to the transmission power of the terminal.

● CI-PSFCH send and AN-PSFCH receive: in the event that the terminal cannot transmit and receive simultaneously, the reception of AN-PSFCH may always have a higher priority than the transmission of CI-PSFCH. Thus, the terminal (e.g., UE-a) may preferentially perform the receiving operation of AN-PSFCH. Or based on a result of comparing the highest priority among priorities of CI-PSFCH to be transmitted with the highest priority among priorities of AN-PSFCH to be received, the terminal (e.g., UE-a) may selectively perform a transmission or reception operation according to the higher priority. In this case, if the highest priorities are identical to each other, the comparison of the next highest priorities may be sequentially performed.

● CI-PSFCH receive and AN-PSFCH transmit: in the event that the terminal cannot transmit and receive simultaneously, the transmission of AN-PSFCH may always have a higher priority than the reception of CI-PSFCH. Thus, the terminal (e.g., UE-a) may preferentially perform the transmission operation of AN-PSFCH. Or based on the result of comparing the highest priority among the priorities of CI-PSFCH to be received with the highest priority among the priorities of AN-PSFCH to be transmitted, the terminal (e.g., UE-a) may selectively perform a transmission or reception operation according to the higher priority. In this case, if the highest priorities are identical to each other, the comparison of the next highest priorities may be sequentially performed.

● CI-PSFCH reception and AN-PSFCH reception: when the number of PSFCH that the terminal can simultaneously receive and process is preconfigured according to the capability of the terminal, the terminal (e.g., UE-B) can assume that AN-PSFH has a higher priority than CI-PSFCH at all times and can preferentially perform the receiving operation of AN-PSFCH. Or without distinguishing AN-PSFCH from CI-PSFCH, the terminal (e.g., UE-B) may compare the priority of AN-PSFCH to be received with the priority of CI-PSFCH to be received and preferentially transmit PSFCH with higher priority.

As described above, whether AN-PSFCH has always a higher priority than CI-PSFCH or whether a transmission or reception operation for a higher priority is preferentially performed without distinguishing between CI-PSFCH and AN-PSFCH may be configured by system information, UE-specific RRC signaling, or MAC CE.

If AN-PSFCH has a higher priority than CI-PSFCH throughout the above procedure, confusion may occur when considering the priority of channels other than PSFCH. For example, it may be assumed that the priorities of the plurality of channels may be configured in the order of 'CI-PSFCH > CH#A (i.e., any channel other than PSFCH) > AN-PSFCH'. In this case, if the priority of AN-PSFCH and the priority of ch#a are compared first, ch#a may be selected. Then, if the priority of CH#A is compared with the priority of CI-PSFCH, CI-PSFCH may be finally selected. However, if the priority of AN-PSFCH and the priority of CI-PSFCH are compared first, AN-PSFCH may always be selected regardless of the actual priority. Then, if the priority of AN-PSFCH is compared with the priority of ch#a, ch#a may be finally selected. Thus, the final selected channel may vary depending on which channels are first compared for priority. Therefore, priority between PSFCH may be preferentially compared to prevent such confusion. That is, after first comparing the priorities of CI-PSFCH and AN-PSFCH, the priorities of the other channels may be compared. In addition, when there are multiple CIs-PSFCH and multiple ANs-PSFCH, the same type of PSFCH may be compared first for priority. That is, the priorities of the plurality of CIs PSFCH are compared, and the priorities of the plurality of ANs PSFCH are compared. The priority between the selected PSFCH (i.e., CI-PSFCH and AN-PSFCH) may then be compared, and then may be compared to the priority of the other channels.

Meanwhile, it is necessary to define an operation when transmission/reception of CI-PSFCH occurs simultaneously with LTE-side uplink transmission/reception and uplink transmission. As AN exemplary embodiment, even when the transmission/reception of the CI-PSFCH occurs simultaneously with the LTE-side uplink transmission/reception and the uplink transmission, the conventional scheme applied when the transmission/reception of the AN-PSFCH occurs simultaneously with the LTE-side uplink transmission/reception and the uplink transmission can be applied as it is. Further, when the transmission/reception of CI-PSFCH and the transmission/reception of AN-PSFCH occur synchronously with the LTE side uplink transmission/reception and uplink transmission, priority between CI-PSFCH and AN-PSFCH may be considered first, and priority compared with the LTE side uplink transmission/reception and uplink transmission may be considered.

In scheme 2, when there are two or more terminals causing a collision in a specific resource, UE-a may select a specific terminal among the plurality of terminals as UE-B and transmit collision related information. In this case, a specific terminal to which collision related information is transmitted among terminals causing collisions may be preconfigured as UE-B. This may be performed during link setup by PC5-RRC signaling between UE-a and a particular terminal (i.e., UE-B). As another method, after a plurality of terminals causing a collision (each pair including two terminals) may be configured in pairs, terminals in each pair having a lower priority (i.e., a higher priority value) may be configured as UE-B, and collision prediction information may be transmitted to the UE-B. For example, when it is predicted that terminals ue#1, ue#2, and ue#3 cause collision in overlapping resources, pairs #1{ ue#1, ue#2}, pairs #2{ ue#1, ue#3} and pairs #3{ ue#2, ue#3} may be configured. If terminals ue#1, ue#2, and ue#3 have priorities in the order of 'ue#1 > ue#2 > ue#3' (i.e., priority value of ue#1 < priority value of ue#2 < priority value of ue#3), terminal ue#2 may be selected from pair #1, terminal ue#3 may be selected from pair #2, terminal ue#3 may be selected from pair #3, and UE-a may select terminals ue#2 and ue#3 as UE-B and transmit collision prediction information to them. As described above, when UE-a needs to transmit collision prediction information to a plurality of UE-bs (e.g., ue#2 and ue#3) through CI-PSFCH, if the number of CIs-PSFCH that UE-a can transmit is limited, UE-a may perform an additional UE-B selection procedure to satisfy the limited number. More specifically, the UE-A may send the CI-PSFCH by selecting a lower priority terminal among the plurality of UE-B. In the above example, when it is possible to transmit to only one of the terminals ue#2 and ue#3, UE-a may eventually select the terminal ue#3 as UE-B and transmit CI-PSFCH to the terminal ue#3. When a plurality of terminals (e.g., ue#2 and ue#3) have the same priority, UE-a can practically select an arbitrary terminal. Or when multiple terminals (e.g., ue#2 and ue#3) have the same priority, UE-a may select UE-B based on the measured RSRP. In this case, a terminal with a large RSRP or a terminal with a small RSRP may be configured to be selected as the UE-B. Further, the UE-B may be selected according to various criteria that are pre-configured, such as the size of the data or the size of the resource region where collisions are predicted. If the terminal selected according to the above criteria does not support scheme 2, the UE-a may not transmit resource coordination information (i.e., collision prediction information) to the selected terminal, or if the selected terminal supports scheme 2, the UE-a may select a terminal having the next lower priority as the UE-B and transmit resource coordination information (i.e., collision prediction information) to the selected terminal. In the above example, if terminal ue#3 does not support scheme 2, UE-a may not transmit CI-PSFCH to ue#3 or select terminal ue#2 as UE-B and transmit CI-PSFCH to terminal ue#2.

Operations of the method according to the exemplary embodiments of the present disclosure may be embodied as computer readable programs or codes in a computer readable recording medium. The computer readable recording medium may include all types of recording devices for storing data that can be read by a computer system. Furthermore, the computer-readable recording medium may store and execute a program or code that can be distributed in computer systems connected through a network and read by a computer in a distributed manner.

The computer-readable recording medium may include a hardware device specifically configured to store and execute program commands, such as ROM, RAM, or flash memory. The program commands may include not only machine language code created by a compiler but also high-level language code that may be executed by a computer using an interpreter.

Although some aspects of the present disclosure have been described in the context of apparatus, these aspects may indicate corresponding descriptions in terms of methods, and blocks or apparatus may correspond to steps or features of steps of the methods. Similarly, aspects described in the context of the method may be represented as corresponding blocks or items or features of corresponding devices. Some or all of the steps of the method may be performed by (or using) a hardware device, such as a microprocessor, a programmable computer, or electronic circuitry. In some embodiments, one or more of the most important steps of the method may be performed by such an apparatus.

In some example embodiments, programmable logic devices such as field programmable gate arrays may be used to perform some or all of the functions of the methods described herein. In some exemplary embodiments, a field programmable gate array may be operated with a microprocessor to perform one of the methods described herein. In general, the methods are preferably performed by specific hardware devices.

The description of the disclosure is merely exemplary in nature and, thus, variations that do not depart from the gist of the disclosure are intended to be within the scope of the disclosure. Such variations are not to be regarded as a departure from the spirit and scope of the disclosure. It will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope as defined by the following claims.

Claims

1. An operating method of a first terminal performing side-link communication, the operating method comprising:

receiving resource coordination information from a second terminal;

Selecting a candidate resource to be used for transmission of the first terminal by prioritizing a preferred resource in response to the resource coordination information being information on the preferred resource; and

In response to the resource coordination information being information about non-preferred resources, the non-preferred resources are excluded from candidate resources to be used for transmission by the first terminal.

2. The operating method of claim 1, wherein the second terminal is a terminal that receives data transmitted by the first terminal.

3. The method of operation of claim 1, wherein the resource coordination information is received through a Medium Access Control (MAC) Control Element (CE) or through a MAC CE and a side-uplink control information (SCI).

4. The method of operation of claim 3, wherein the resource coordination information is configured for each resource pool whether received by a MAC CE or received by a MAC CE and SCI.

5. The method of operation of claim 3, wherein the resource coordination information comprises N Time Resource Indicator Value (TRIV)/Frequency Resource Indicator Value (FRIV) combinations, each of the N TRIV/FRIV combinations indicating M resources, each of N and M being a natural number equal to or greater than 1.

6. The method of operation of claim 5, wherein a time location and a frequency location of a first resource of the M resources indicated by each of the N TRIV/FRIV combinations is also included in the resource coordination information.

7. The method of operation of claim 6, wherein the frequency location of the first resource is indicated by a starting subchannel index.

8. The method of operation of claim 6, wherein a time position of a first resource of the M resources indicated by a first TRIV/FRIV combination of the N TRIV/FRIV combinations is indicated as a reference time slot and a time position of a first resource of the remaining TRIV/FRIV combinations other than the first TRIV/FRIV combination is indicated by a time slot offset relative to the reference time slot.

9. The method of operation of claim 5 wherein the resource range indicated by the N TRIV/FRIV combinations when the resource coordination information is received by the MAC CE is different from the resource range indicated by the N TRIV/FRIV combinations when the resource coordination information is received by the MAC CE and SCI.

10. The method of operation of claim 1, wherein the resource coordination information is received from the second terminal based on an explicit request of the first terminal or is received from the second terminal according to satisfaction of a predetermined condition without an explicit request of the first terminal.

11. An operating method of a second terminal performing side-link communication, the operating method comprising:

Generating resource coordination information, which is information about preferred resources or non-preferred resources for transmission of the first terminal; and

Transmitting the resource coordination information to the first terminal,

Wherein when the resource coordination information is information on a preferred resource, a candidate resource to be used for transmission of the first terminal is selected by prioritizing the preferred resource, and when the source coordination information is information on a non-preferred resource, the non-preferred resource is excluded from the candidate resources to be used for transmission of the first terminal.

12. The method of operation of claim 11, wherein the resource coordination information is transmitted through a Medium Access Control (MAC) Control Element (CE) or through a MAC CE and a side-uplink control information (SCI).

13. The method of operation of claim 12 wherein the resource coordination information is configured for each resource pool to be sent by a MAC CE or by a MAC CE and SCI.

14. The method of operation of claim 13, wherein the resource coordination information comprises N Time Resource Indicator Value (TRIV)/Frequency Resource Indicator Value (FRIV) combinations, each of the N TRIV/FRIV combinations indicating M resources, each of N and M being a natural number equal to or greater than 1.

15. The method of operation of claim 14, wherein a time location and a frequency location of a first resource of M resources indicated by each of the N TRIV/FRIV combinations is also included in the resource coordination information.

16. The method of operation of claim 14, wherein a time position of a first resource of the M resources indicated by a first TRIV/FRIV combination of the N TRIV/FRIV combinations is indicated as a reference time slot and a time position of a first resource of the remaining TRIV/FRIV combinations other than the first TRIV/FRIV combination is indicated by a time slot offset relative to the reference time slot.

17. The method of operation of claim 14 wherein the resource range indicated by the N TRIV/FRIV combinations when the resource coordination information is received by a MAC CE is different from the resource range indicated by the N TRIV/FRIV combinations when the resource coordination information is received by a MAC CE and SCI.

18. A first terminal that performs side-uplink communications, comprising:

At least one transceiver; and

A processor controlling the at least one transceiver,

Wherein the processor causes the first terminal to perform:

Receiving resource coordination information from a second terminal by using the transceiver;

19. The first terminal of claim 18, wherein the resource coordination information includes N Time Resource Indicator Value (TRIV)/Frequency Resource Indicator Value (FRIV) combinations, each of the N TRIV/FRIV combinations indicating M resources, each of N and M being a natural number equal to or greater than 1.

20. The first terminal of claim 19, wherein the resource range indicated by the N TRIV/FRIV combinations when the resource coordination information is received by the MAC CE is different from the resource range indicated by the N TRIV/FRIV combinations when the resource coordination information is received by the MAC CE and SCI.