Operating method of terminal performing V2X communication in wireless communication system, and apparatus using method

In a wireless communication system, a third party different from both terminals or a base station, which are parties to vehicle-to-everything (V2X) communication, may be involved in resource allocation for the V2X communication. For example, a first terminal performing V2X communication with a second terminal receives recommendation information recommending a resource available for the V2X communication from a third terminal and performs the V2X communication with the second terminal by using a recommended resource determined based on the recommendation information or a resource selected by the first terminal based on the recommendation information.

BACKGROUND OF THE INVENTION

Field of the Invention

The present disclosure relates to wireless communication, and more particularly, to an operation method of a terminal performing vehicle-to-everything (V2X) communication in a wireless communication system and an apparatus using the method.

Related Art

As a wider range of communication devices require larger communication capacities, the need for mobile broadband communication that is more enhanced than the existing Radio Access Technology (RAT) is rising. In addition, massive machine type communications (massive MTC) which provides a variety of services anytime, anywhere by connecting multiple devices and objects, is also one of the major issues to be considered in next-generation communication.

Communication system design considering services or terminals sensitive to reliability and latency is being discussed. Next-generation wireless access technology considering improved mobile broadband communication, massive MTC, and ultra-reliable and low latency communication (URLLC) may be referred to as a new radio access technology (RAT) or a new radio (NR).

Meanwhile, V2X (vehicle-to-everything) communication may also be supported in NR. V2X communication means communication between a terminal installed in a vehicle and an arbitrary terminal, for example, a terminal installed in another vehicle, a terminal of a pedestrian, and/or a terminal as an infrastructure.

There are various communication modes for V2X communication. For example, there are mode 3 and mode 4. Mode 3 is a mode in which when a terminal has data to send, the terminal requests scheduling to a base station (eNB) and transmits the data according to a resource allocated by the base station. Mode 4 is a mode in which when a terminal has data to send, the terminal autonomously selects a resource and transmits the data through a sensing process in a set resource pool (resource pool), without the aid of a base station.

In future V2X communication, the deployment of a base station, a roadside unit, and the like may be significantly different from the present one. Accordingly, a resource allocation method for a new mode that is different from the existing modes may be required.

SUMMARY OF THE INVENTION

The technical problem to be solved by the present disclosure is to provide an operation method of a terminal performing V2X communication in a wireless communication system and an apparatus using the method.

In one aspect, a method of operating a first terminal performing vehicle-to-everything (V2X) communication with a second terminal in a wireless communication system is provided. The method includes, receiving, from a third terminal, recommendation information for recommending a resource available for the V2X communication, and performing the V2X communication with the second terminal by using a recommended resource determined based on the recommendation information or a resource selected by the first terminal based on the recommendation information.

A first terminal provided in another aspect includes a transceiver configured to transmit and receive a radio signal and a processor coupled to the transceiver and configured to receive, from a third terminal, recommendation information for recommending a resource available for V2X communication, and perform the V2X communication with a second terminal by using a recommended resource determined based on the recommendation information or a resource selected by the first terminal based on the recommendation information.

A processor for the first terminal provided in another aspect configured to control the first terminal to receive, from a third terminal, recommendation information recommending a resource available for V2X communication, and perform the V2X communication with a second terminal by using a recommended resource determined based on the recommendation information or a resource selected by the first terminal based on the recommendation information.

A terminal other than the party terminal performing V2X communication may recommend a resource, which may be used for the V2X communication, to the party terminal. This method may also be applied to a resource pool capable of selecting a resource for V2X terminal itself, and may utilize the resource pool more efficiently.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

FIG.1illustrates a structure of an wireless communication system. This may also be referred to as an Evolved-UMTS Terrestrial Radio Access Network (E-UTRAN), or a Long Term Evolution (LTE)/LTE-A system.

The E-UTRAN includes a base station (BS)20, which provides a control plane and a user plane to a terminal10(a user equipment, UE). The terminal10may be fixed or mobile and may also be referred to by using different terms, such as Mobile Station (MS), User Terminal (UT), Subscriber Station (SS), Mobile Terminal (MT), wireless device, and so on. The base station20refers to a fixed station that communicates with the terminal10and may also be referred to by using different terms, such as evolved-NodeB (eNB), Base Transceiver System (BTS), Access Point (AP), and so on.

The base stations20are interconnected to one another through an X2 interface. The base stations20are connected to an Evolved Packet Core (EPC)30through an S1 interface. More specifically, the base station20are connected to a Mobility Management Entity (MME) through an S1-MME interface and connected to Serving Gateway (S-GW) through an S1-U interface.

The EPC30is configured of an MME, an S-GW, and a Packet Data Network-Gateway (P-GW). The MME has UE access information or UE capability information, and such information may be primarily used in UE mobility management. The S-GW is a gateway having an E-UTRAN as its endpoint. And, the P-GW is a gateway having a Packet Data Network (PDN) as its endpoint.

Layers of a radio interface protocol between the UE and the network may be classified into a first layer (L1), a second layer (L2), and a third layer (L3) based on the lower three layers of an open system interconnection (OSI) model, which is well-known in the communication system, and, a physical layer belonging to the first layer provides a physical channel using an information transfer service, and a Radio Resource Control (RRC) layer, which is located in the third layer, executes a function of controlling radio resources between the UE and the network. For this, the RRC layer exchanges RRC messages between the UE and the base station.

FIG.2illustrates a radio protocol architecture of a user plane.FIG.3shows a radio protocol architecture of a control plane. The user plane is a protocol stack for user data transmission, and the control plane is a protocol stack for control signal transmission.

Referring toFIG.2andFIG.3, a physical (PHY) layer belongs to the L1. A physical (PHY) layer provides an information transfer service to a higher layer through a physical channel. The PHY layer is connected to a medium access control (MAC) layer. Data is transferred (or transported) between the MAC layer and the PHY layer through a transport channel. The transport channel is sorted (or categorized) depending upon how and according to which characteristics data is being transferred through the radio interface.

Between different PHY layers, i.e., a PHY layer of a transmitter and a PHY layer of a receiver, data is transferred through the physical channel. The physical channel may be modulated by using an orthogonal frequency division multiplexing (OFDM) scheme and uses time and frequency as radio resource.

The functions of the MAC layer include mapping between logical channels and transport channels, and multiplexing/demultiplexing into transport blocks provided as physical channels on a transport channel of a MAC service data unit (SDU) belonging to the logical channel. The MAC layer provides a service to a Radio Link Control (RLC) layer through a logical channel.

The radio resource control (RRC) layer is defined only in a control plane. The RRC layer performs a function of controlling logical channel, transport channels, and physical channels in relation with configuration, re-configuration, and release of radio bearers. The RB refers to a logical path being provided by the first layer (PHY layer) and the second layer (MAC layer, RLC layer, Packet Data Convergence Protocol (PDCP) layer) in order to transport data between the UE and the network.

Functions of a PDCP layer in the user plane include transfer, header compression, and ciphering of user data. Functions of a PDCP layer in the control plane include transfer data of control plane and ciphering/integrity protection.

The configuration of the RB refers to a process for specifying a radio protocol layer and channel properties in order to provide a particular service and for determining respective detailed parameters and operation methods. The RB may then be classified into two types, i.e., a signaling radio bearer (SRB) and a data radio bearer (DRB). The SRB is used as a path for transmitting an RRC message in the control plane, and the DRB is used as a path for transmitting user data in the user plane.

When an RRC connection is established between an RRC layer of the UE and an RRC layer of the E-UTRAN, the UE is in an RRC connected state, and, otherwise, the UE may be in an RRC idle state.

Downlink transport channels for transmitting data from a network to a terminal include a Broadcast Channel (BCH) transmitting system information and a downlink Shared Channel (SCH) transmitting user traffic or control messages. Traffic or control messages of downlink multicast or broadcast services may be transmitted via the downlink SCH or may be transmitted via a separate downlink Multicast Channel (MCH). Meanwhile, uplink transport channels for transmitting data from the terminal to the network include a Random Access Channel (RACH) transmitting initial control messages and an uplink Shared Channel (SCH) transmitting user traffic or control messages.

Logical channels that is at an upper level than the transport channel and is mapped to the transport channel may include a Broadcast Control Channel (BCCH), a Paging Control Channel (PCCH), a Common Control Channel (CCCH), a Multicast Control Channel (MCCH), a Multicast Traffic Channel (MTCH), and so on.

A physical channel is configured of a plurality of OFDM symbols in the time domain and a plurality of sub-carriers in the frequency domain. One subframe is configured of a plurality of OFDM symbols in the time domain. A resource block is configured of a plurality of OFDM symbols and a plurality of sub-carriers in resource allocation units. Additionally, each subframe may use specific sub-carriers of specific OFDM symbols (e.g., first OFDM symbol) of the corresponding subframe for a Physical Downlink Control Channel (PDCCH), i.e., L1/L2 control channels. A Transmission Time Interval (TTI) refers to a unit time of a subframe transmission.

Hereinafter, a new radio access technology (new RAT) will be described. The new radio access technology may also be referred to as new radio (NR).

As more communication devices require a larger communication capacity, there is a need for improved mobile broadband communication compared to a conventional radio access technology (RAT). In addition, Massive Machine Type Communications (MTC), which provides a variety of services anytime, anywhere by connecting multiple devices and objects, is also one of the major issues to be considered in next-generation communication. Further, a communication system design that considers services/terminals sensitive to reliability and latency is being discussed. The introduction of next-generation wireless access technology in consideration of such enhanced mobile broadband communication, massive MTC, and Ultra-Reliable and Low Latency Communication (URLLC) is under discussion, and in the present disclosure, for convenience, the corresponding technology is called new RAT or NR.

FIG.4illustrates a structure of a new generation radio access network (NG-RAN) system where an NR system is applied.

Referring toFIG.4, the NG-RAN may include a next generation-Node B (gNB) and/or eNB providing a protocol termination of a user plane and control plane to a user.FIG.4exemplifies a case where the NG-RAN includes only the gNB. The gNB and the eNB are connected to one another via Xn interface. The gNB and the eNB are connected to one another via 5th Generation (5G) Core Network (5GC) and NG interface. More specifically, the gNB and the eNB are connected to an access and mobility management function (AMF) via NG-C interface, and the gNB and the eNB are connected to a user plane function (UPF) via NG-U interface.

FIG.5illustrates a functional division between an NG-RAN and a 5GC.

Referring toFIG.5, the gNB may provide functions, such as Inter Cell Radio Resource Management (RRM), Radio Bearer (RB) control, Connection Mobility Control, Radio Admission Control, Measurement Configuration & Provision, Dynamic Resource Allocation, and so on. An AMF may provide functions, such as Non Access Stratum (NAS) security, idle state mobility processing, and so on. A UPF may provide functions, such as Mobility Anchoring, Protocol Data Unit (PDU) processing, and so on. A Session Management Function (SMF) may provide functions, such as UE Internet Protocol (IP) address allocation, PDU session control, and so on.

FIG.6illustrates physical channels used in a wireless communication system and a general signal transmission process.

In the wireless communication system, a terminal receives information from a base station through a downlink (DL), and the terminal transmits information to the base station through an uplink (UL). The information transmitted and received by the base station and the terminal includes data and various control information, and various physical channels exist according to the type/purpose of the information they transmit and receive.

When being powered on again from a power off state or when newly entering a cell, a terminal performs an initial cell search operation such as synchronizing with a base station (S11). To this end, the terminal receives a primary synchronization channel (PSCH) and a secondary synchronization channel (SSCH) from the base station to synchronize with the base station and acquires information such as cell identity (cell ID) and so on. In addition, the terminal may receive a physical broadcast channel (PBCH) from the base station to obtain broadcasting information on a cell. In addition, the terminal may monitor the downlink channel state by receiving a downlink reference signal (DL RS) in the initial cell search phase.

After completing the initial cell search, the UE may acquire more detailed system information by receiving a physical downlink control channel (PDCCH) and a corresponding physical downlink control channel (PDSCH) (S12).

Thereafter, the UE may perform a random access procedure to complete the access to the base station (S13to S16). Specifically, the UE may transmit a preamble through a physical random access channel (PRACH) (S13), and receive a random access response (RAR) for the preamble through a PDCCH and a corresponding PDSCH (S14). Thereafter, the UE may transmit a physical uplink shared channel (PUSCH) using scheduling information in the RAR (S15) and perform a contention resolution procedure such as a PDCCH and a corresponding PDSCH (S16).

After performing the above-described procedure, the UE may perform PDCCH/PDSCH reception (S17) and PUSCH/PUCCH (Physical Uplink Control Channel) transmission (S18) as general uplink/downlink signal transmission procedures. Control information transmitted by the UE to the base station may be referred to as uplink control information (UCI). The UCI may include Hybrid Automatic Repeat and reQuest Acknowledgement/Negative-ACK (HARQ ACK/NACK), scheduling request (SR), channel state information (CSI) and the like. The CSI may include a channel quality indicator (CQI), a precoding matrix indicator (PMI), and a rank indication (RI). UCI is generally transmitted through PUCCH but may also be transmitted through PUSCH when control information and data should be simultaneously transmitted. In addition, according to the request/instruction of a network, the UE may aperiodically transmit UCI through PUSCH.

Meanwhile, a new RAT system such as NR may use an OFDM transmission scheme or a similar transmission scheme. The new RAT system may follow OFDM parameters different from those of LTE. Alternatively, the new RAT system may follow the existing LTE/LTE-A numerology, but may have a larger system bandwidth (e.g., 100 MHz). Alternatively, a single cell may support multiple numerologies. That is, UEs operating with different numerologies may coexist in one cell.

FIG.7illustrates the structure of a radio frame used in NR.

Table 1 shown below represents an example of a number of symbols per slot (Nslotsymb), a number slots per frame (Nframe,uslot), and a number of slots per subframe (Nsubframe,uslot) in accordance with an SCS configuration (u), in a case where a normal CP is used.

Table 2 shows an example of a number of symbols per slot, a number of slots per frame, and a number of slots per subframe in accordance with the SCS, in a case where an extended CP is used.

FIG.8shows a structure of a slot of an NR frame.

A carrier includes a plurality of subcarriers in a frequency domain. A Resource Block (RB) may be defined as a plurality of consecutive subcarriers (e.g., 12 subcarriers) in the frequency domain A Bandwidth Part (BWP) may be defined as a plurality of consecutive (Physical) Resource Blocks ((P)RBs) in the frequency domain, and the BWP may correspond to one numerology (e.g., SCS. CP length, and so on). A carrier may include a maximum of N number BWPs (e.g., 5 BWPs). Data communication is performed through an activated BWP, and one BWP may be activated for one terminal. Each element in the resource grid is referred to as a resource element (RE), and one complex symbol may be mapped.

FIG.9illustrates the structure of a self-contained slot.

An NR system may support a self-contained structure where a DL control channel, a DL or UL data channel, and a UL control channel may all be included in a single slot. For example, first N symbols in a slot may be used to transmit the DL control channel (hereinafter, DL control region), and last M symbols in the slot may be used to transmit the UL control channel (hereinafter, UL control region). N and M are each an integer of 0 or more. A resource region (hereinafter referred to as data region) between the DL control region and the UL control region may be used for DL data transmission or may be used for UL data transmission.

As an example, one slot may have any of the following configurations. Each section is listed in chronological order.1. DL only configuration2. UL only configuration3. Mixed UL-DL configurationDL region+GP (Guard Period)+UL control regionDL control region+GP+UL region

Here, the DL region may be (i) a DL data region or (ii) a DL control region+a DL data region, and the UL region may be (i) a UL data region or (ii) a UL data region+a UL control region.

A PDCCH may be transmitted in a DL control region, and a PDSCH may be transmitted in a DL data region. A PUCCH may be transmitted in a UL control region, and a PUSCH may be transmitted in a UL data region. In a PDCCH, downlink control information (DCI), for example. DL data scheduling information, UL data scheduling information, and the like may be transmitted. In a PUCCH, uplink control information (UCI), for example, positive acknowledgment (ACK/negative acknowledgment (NACK) information for DL data, channel state information (CSI) information, and scheduling request (SR) may be transmitted. A GP provides a time gap in a process where a base station and UE switch from the transmission mode to the reception mode or from the reception mode to the transmission mode. In a subframe, some symbols at a time point of switching from DL to UL may be set to GP.

Meanwhile, the present disclosure may be applied to V2X communication. Although the present disclosure is described with a focus on V2X communication of NR, it may also be applied to other scenarios such as V2V or device-to-device (D2D) communication.

Referring toFIG.10, in V2X/D2D communication, the term terminal may mainly denotes a terminal used by a user. However, in case a network equipment, such as a base station, transmits and receives signals in accordance with a communication scheme between the network equipment and a terminal, the base station may also be considered as a type of the terminal.

A terminal1may select a resource unit corresponding to a specific resource within a resource pool, which refers to a set of resources, and the terminal1may then be operated so as to transmit a SL signal by using the corresponding resource unit. A terminal2, which is to a receiving terminal, may be configured with a resource pool to which the terminal1can transmit signals, and may then detect signals of the terminal1from the corresponding resource pool.

Herein, in case the terminal1is within a connection range of the base station, the base station may notify the resource pool. Conversely, in case the terminal1is outside a connection range of the base station, another terminal may notify the resource pool or a pre-determined resource may be used.

Generally, a resource pool may be configured in a plurality of resource units, and each UE may select one resource unit or a plurality of resource units and may use the selected resource unit(s) for its SL signal transmission.

FIG.11illustrates operations by a terminal according to a transmission mode (TM) related to V2X/D2D.

(a) ofFIG.11is related to a transmission mode 1 or a transmission mode 3, and (b) ofFIG.11is related to a transmission mode 2 or a transmission mode 4. In transmission modes 1/3, the base station performs resource scheduling to terminal1via PDCCH (more specifically, Downlink Control Information (DCI)), and terminal1performs D2D/V2X communication with terminal2according to the corresponding resource scheduling. After transmitting sidelink control information (SCI) to terminal2via physical sidelink control channel (PSCCH), terminal1may transmit data based on the SCI via physical sidelink shared channel (PSSCH). The transmission mode 1 may be applied to a D2D, and transmission mode 3 may be applied to a V2X.

The transmission modes 2/4 is modes where the UE schedules resources by itself. More specifically, the transmission mode 2 may be applied to a D2D, and the UE may select a resource from a predetermined resource pool by itself and then perform D2D operations. Transmission mode 4 may be applied to a V2X, and the UE may select a resource within a selection window on its own by performing a sensing/SA decoding procedure and so on, and then perform V2X operations. After transmitting the SCI to terminal2via PSCCH, terminal1may transmit SCI-based data via PSSCH. Hereinafter, the transmission mode may be abbreviated to the term ‘mode’.

Control information transmitted by a base station to UE through a PDCCH may be referred to as downlink control information (DCI), whereas control information transmitted by UE to another UE through a PSCCH may be referred to as SCI. SCI may deliver sidelink scheduling information SCI may have various formats, for example, SCI format 0 and SCI format 1.

The SCI format 0 may be used for scheduling of a PSSCH. The SCI format 0 may include a frequency hopping flag (1 bit), resource block allocation and hopping resource allocation fields (the number of bits may depend on the number of resource blocks of the sidelink), a time resource pattern (7 bits), a modulation and coding scheme (MCS, 5 bits), time advance indication (11 bits), a group destination ID (8 bits), and the like.

The SCI format 1 may be used for scheduling of a PSSCH. The SCI format 1 includes priority (3 bits), resource reservation (4 bits), frequency resource location of initial transmission and retransmission (the number of bits may depend on the number of subchannels of the sidelink), a time gap between initial transmission and retransmission (4 bits). MCS (5 bits), a retransmission index (1 bit), a reserved information bit, and the like. The reserved information bit may be abbreviated to a reserved bit. The reserved bit may be added until the bit size of SCI format 1 becomes 32 bits. That is, the SCI format 1 includes a plurality of fields including different information, and the remaining number of bits obtained by excluding the total number of bits of the plurality of fields from the fixed total number of bits (32 bits) of the SCI format 1 may be referred to as reserved bits.

SCI format 0 may be used for transmission modes 1 and 2, and SCI format 1 may be used for transmission modes 3 and 4.

Meanwhile, there may be various types of V2X transmission resource pools.

FIG.12illustrates sensing and resource selection in mode 4 and types of V2X transmission resource pool.

Referring to (a) ofFIG.12, a V2X transmission resource pool may be a resource pool in which only (partial) sensing is allowed. In the V2X transmission resource pool, UE should select a V2X transmission resource after performing (partial) sensing, and random selection may not be allowed. The V2X transmission resource selected by (partial) sensing may be semi-statically maintained at a predetermined interval as shown in (a) ofFIG.12.

A base station may configure UE to perform a scheduling allocation decoding or energy measurement-based sensing operation thereby performing V2X message transmission on the V2X transmission resource pool.

Referring to (b) ofFIG.12, a V2X transmission resource pool may be a resource pool in which only random selection is allowed. In the V2X transmission resource pool, UE does not perform sensing but may randomly select a V2X transmission resource in the selection window.

Meanwhile, although not illustrated inFIG.12, there may be a resource pool capable of both sensing and random selection. The base station may inform that a V2X resource may be selected by one of sensing and random selection in this resource pool.

Selection of a resource for transmitting a V2X signal to UE may be triggered. For example, assume that the transmission resource selection is triggered in the subframe #m. In this case, UE may select a resource for V2X signal transmission in a subframe period from subframes #m+T1 to #m+T2. Hereinafter, the subframe period from the subframes #m+T1 to #m+T2 may be referred to as a selection window. For example, the selection window may be composed of 100 consecutive subframes.

In the selection window, UE may select some subframes as candidate resources. In order to select (/reserve) a specific subframe among the some subframes, for example, a subframe #N(SF #N) as a V2X transmission subframe capable of transmitting a V2X signal, the UE may have to sense at least one subframe linked to or associated with the subframe #N. An (entire) subframe period defined for sensing is referred to as a sensing window and may be composed of 1,000 subframes, for example. For example, in the sensing window, UE may sense subframes corresponding to the subframe #N-100*k (where k may be a set of elements in the range [1, 10] and be a predefined value or a value configured by a network). For example, UE may estimate/determine whether or not subframe #N is being used by another V2X terminal or whether or not there is a relatively high interference (equal to or above a predefined(/signaled) threshold) on subframe #N by sensing the subframes #N-1000, #N-700, #N-500, #N-300, and #N-100 and may finally select subframe #N according to the result.

FIG.13illustrates an example of a structure of a resource unit.

Referring toFIG.13, all the frequency resources of a resource pool may be divided into NF pieces and total time resources of the resource pool may be divided into NT pieces so that a total of NF*NT resource units may be defined in the resource pool.

Herein, it is illustrated that an example in which the resource pool is repeated every NT subframes.

One resource unit (e.g., Unit #0) may be periodically repeated, as shown inFIG.13. Alternatively, in order to obtain a diversity effect in a time or frequency dimension, an index of a physical resource unit to which one logical resource unit is mapped may change in a predetermined pattern according to time. In this resource unit structure, a resource pool may mean a set of resource units that UE may use to transmit a D2D signal.

Resource pools may be subdivided into several types. For example, resource pools may be classified according to the contents of D2D signals transmitted from each resource pool. Each resource pool may be distinguished as follows, and the content of a next D2D signal may be transmitted in each resource pool.

1) Scheduling assignment (SA) resource pool or D2D (sidelink) control channel, a resource pool in which each transmission terminal transmits a signal including a resource location of a D2D data channel, which is transmitted in a same or subsequent subframe, and other information necessary to demodulate the data channel (e.g., a modulation and coding scheme (MCS), a MIMO transmission method, timing advance, etc.).

The signal described in 1) may be multiplexed and transmitted together with D2D data in a same resource unit. In this case, the SA resource pool may mean a resource pool in which SA is transmitted after being multiplexed with D2D data. The SA resource pool may be referred to as a D2D (sidelink) control channel.

2) D2D data channel: a resource pool used by a transmission terminal to transmit user data using a resource designated through SA. When D2D data and SA information are multiplexed and transmitted together in a same resource unit, a resource pool for a D2D data channel may be configured to transmit only the D2D data channel excluding the SA information. In other words, a resource element that was used to transmit SA information in each resource unit within an SA resource pool is still used to transmit D2D data in a D2D data channel resource pool.

3) Discovery channel: a resource pool where a transmission terminal transmits a message including information such as its identity (ID) to enable a neighboring terminal to discover the transmission terminal.

Even when the D2D signal described above has a same content, different resource pools may be used according to transmission/reception properties of the D2D signal. For example, even a same D2D data channel or discovery message may be further classified into different resource pools according to a method of determining transmission timing for a D2D signal (e.g., whether it is transmitted at the reception time of a synchronization reference signal or by applying a predetermined timing advance at the reception time) or a resource assignment method (e.g., whether a base station designates a transmission resource of each signal to each transmission terminal or whether each transmission terminal itself selects each signal transmission resource within a resource pool), a signal format (e.g., the number of symbols occupied by each D2D signal in a single subframe or the number of subframes used to transmit one D2D signal), signal strength from the base station, the transmission power strength of a D2D terminal, etc.

As described above, in D2D communication, a method in which a base station directly indicates a transmission resource of a D2D transmission terminal may be referred to as Mode 1, and a method in which a transmission resource region is pre-configured or a base station designates a transmission resource region and then UE itself selects a transmission resource may be referred to as Mode 2.

In the case of D2D discovery, when a base station directly indicates a resource, it may be referred to as Type 2. When UE directly selects a transmission resource in a pre-configured resource region or a resource region indicated by the base station, it may be referred to as Type 1.

Meanwhile, the D2D may be referred to as a sidelink. SA may be referred to as a physical sidelink control channel (PSCCH), and D2D synchronization signal may be referred to as a sidelink synchronization signal (SSS) Before D2D communication, a control channel transmitting the most basic information may be referred to as a physical sidelink broadcast channel (PSBCH), and the PSBCH may be transmitted together with SSS and be called by another name a physical D2D synchronization channel (PD2DSCH). A signal for notifying that a specific terminal is in the vicinity may include the ID of the specific terminal, and a channel through which the signal is transmitted may be referred to as a physical sidelink discovery channel (PSDCH).

In D2D, only a D2D communication terminal transmitted a PSBCH together with an SSS. For this reason, the measurement of the SSS was performed using a demodulation reference signal (DM-RS) of the PSBCH. An out-coverage terminal may measure the DM-RS of the PSBCH and may determine whether to become a synchronization source by measuring the reference signal received power (RSRP) of the signal.

FIG.14illustrates an example of a frame structure that may be used in NR.

In NR, as shown inFIG.14, a structure in which a control channel and a data channel are time-division multiplexed (TDM) in one TTI may be considered as one frame structure for minimizing latency.

A frame may include a downlink control region, a downlink data or uplink data transmission region, and an uplink control region in sequence. In a downlink control channel, downlink data scheduling information and uplink data scheduling information may be transmitted. In an uplink control channel, acknowledgment/negative acknowledgment (ACK/NACK) for downlink data and channel state information (CSI) may be transmitted. Within a single frame, some of downlink control region/downlink data/uplink data/uplink control region may not be configured In addition, the order may change.

Such a structural characteristic may enable DL transmission and UL transmission to be performed sequentially within a single subframe and thus DL data to be sent and UL ACK/NACK to be received within the single subframe. Consequentially, when a data transmission error occurs, it may take a shorter time to retransmit data, thereby minimizing latency of ultimate data delivery.

Such a self-contained subframe structure may need a time gap for a process in which a base station and UE are switched from a transmission mode to a reception mode or from a reception mode to a transmission mode. To this end, some symbols at a time of switching from DL to UL in a self-contained subframe may be set as a guard period (GP).

FIG.15illustrates examples of a frame structure in NR.

Referring toFIG.15, the Type A frame includes a DL control region and a DL data region. The Type B frame includes an UL data region and an UL control region. Herein, the UL control region may be dynamically omitted. The Type C frame includes a DL control region, a DL data region. GP and an UL control region. The Type D frame includes a DL control region, GP, an UL data region and an UL control region. Herein, the UL data region and the UL control region may change their positions between each other, and the UL control region may be dynamically omitted.

Hereinafter, a resource allocation scheme is proposed in which a third party (e.g., a road side unit (RSU) or a master terminal) is either directly or indirectly associated with the resource allocation of UE, a party to V2X communication, for the purpose of efficient resource allocation in NR V2X.

There are two types of sidelink (SL) scheduling for NR V2X: Mode 1 (where a base station performs a scheduling operation) and Mode 2 (where a terminal determines a resource used for V2X communication). Specifically, Mode 2 is a method in which a terminal independently selects a resource in a sidelink resource pool that is usually determined beforehand or is set by a base station.

Meanwhile, in NR V2X, a third party may be involved in scheduling of V2X communication between terminals (e.g., a first terminal and a second terminal). Here, the term ‘third party’ may mean another terminal (third terminal), a terminal-type RSU, or a master terminal among other terminals.

There are two main ways that third parties are involved in scheduling. In the first way, a third party proposes a resource to a (V2X) terminal by using a separate independent resource pool not a resource pool (hereinafter, legacy (L) pool) that is set by an existing Mode 2 terminal for independent determination of resource. In the second way, a third party monitors an L-pool equally like existing terminals and proposes a good resource.

Each way may have its own advantages and disadvantages. As the former way uses an independent resource pool, a specific service or user (e.g., a service with high priority or terminals near an RSU) may be separated, and only a third party may be involved in the independent pool, thereby facilitating resource management. On the other hand, the latter way requires a criterion and a procedure in which a third party proposes a good resource different from existing terminals, but an L-pool may be efficiently used.

It may be a challenge what criterion and method will be used by a third party to determine a good resource (e.g., resource with low interference) and to be involved in resource allocation of terminals. When a third party selects a resource with low interference by using an existing sensing method for monitoring like existing terminals, it may not propose resource with a priority higher than the sensing results of other neighboring terminals. Accordingly, a method of selecting a resource so that a third party has a higher priority may be needed.

At least two sidelink resource allocation modes may be defined for NR-V2X sidelink communication. For example, Mode 1 may be defined as a mode in which a base station schedules sidelink resources used by terminals for sidelink communication, and Mode 2 may be defined as a mode in which a terminal determines a sidelink transmission resource from sidelink resources that are set in advance or by a base station/network (that is, the base station does not perform scheduling).

Mode 2 may include at least one of the following methods: 1) a terminal selects a sidelink resource for transmission on its own, 2) a terminal helps another terminal with selection of a sidelink resource, 3) a configured grant of NR is set for sidelink transmission, and 4) a terminal schedules the sidelink transmission of another terminal.

As described above, it may be a challenge whether to set a resource allowing the involvement of a third party in an independent resource pool or an existing L-pool.

A first case to be described is that a resource allowing the involvement of a third party is configured in an independent resource pool. In this case, first, regulations for the independent resource pool are required. Like the L-pool, an independent resource pool may be defined in advance or be configured by a base station. Unlike the L-pool, as information on the independent pool requires independent transmission/reception (TX/RX), it needs to be known to both of a third party and a terminal. The information on the independent resource pool may be provided through system information and thus be identified by a third party or a terminal.

An independent resource pool is configured by a base station or is configured in advance. However, it may be time-division multiplexed (TDM) with an L-pool for the purpose of coexisting with the L-pool. The advantages obtained from TDM include: mitigating the half duplex problem through separate/independent TX/RX in an L-pool and an independent resource pool that is newly set and preventing a conflict of resource selection with existing terminals through independent resource selection of a third party. The independent resource pool may be time-division multiplexed with an L-pool, and also may be a subset of the L-pool.

A next case to be described is that a resource allowing the involvement of a third party is configured in an L-pool. Tus case may improve the efficiency of resource use in an available frequency band. However, an appropriate technique may be necessary to propose a good resource with a third party being involved but without a new resource pool, and a method for receiving resource allocation assistance from a third party through resource coordination with the third party may be required.

FIG.16illustrates a method for operating a first terminal performing V2X communication with a second terminal in a wireless communication system according to the present disclosure.

Referring toFIG.16, the first terminal receives recommendation information recommending a resource available for V2X communication from a third terminal (S161) and performs the V2X communication with the second terminal by using a recommended resource determined based on the recommendation information or a resource selected by the first terminal based on the recommendation information (S162).

The recommended resource may be a resource that is recommended based on the recommendation information within a second resource pool (i.e., the above-described independent resource pool) different from a first resource pool (i.e., the above-described L-pool) in which the first terminal may select a resource for V2X communication on its own.

Alternatively, the recommended resource may be a resource that is recommended based on the recommendation information within a first resource pool (that is, the above-described L-pool) in which the first terminal may select a resource for V2X communication on its own.

The third terminal having a higher priority than the first terminal and the second terminal may select a resource first within the first resource pool and may inform the first terminal of the selected resource through the recommendation information.

When the third terminal performs a sensing operation in a sensing window and selects first-rate resources (e.g., top 20% resources with good channel quality) among the resources of the selection window based on the sensing operation, the recommendation information may indicate all or a part of the first-rate resources. When the first terminal selects a second ratio of resources with good channel quality among the resources of the selection window based on a sensing operation, the first ratio may have a larger value than the second ratio.

The third terminal may select a resource based on the sensing operation ahead of the first terminal and the second terminal and may inform the first terminal of all or a part of the selected resources through the recommendation information.

When the first terminal detects a resource allocation triggering message broadcasted by the third terminal, the first terminal may transmit a resource allocation request message to the third terminal.

When the first terminal moves beyond a predefined range from the third terminal, the first terminal may transmit a release message for notifying release for the recommended resource to the third terminal. After transmitting the release message, the first terminal may select a resource for V2X communication from a resource pool that is configured by a base station.

When the amount of the recommended resource determined based on the recommendation information is insufficient to perform the V2X communication, the first terminal transmits assistant information to the third terminal, and the assistant information may include information on at least one of a period and an offset for generating a recommendation packet for the first terminal and a priority and the maximum size of the packet of the first terminal.

The first terminal is a terminal moving at a predefined speed or less and may be a terminal located at a predefined time or more within the communication coverage of the third terminal.

The recommended resource may be limitedly used. For example, the recommended resource may be used only when the first terminal performs retransmission to the second terminal. Alternatively, the recommended resource may be a resource that assists in selecting a resource for retransmission only when the second terminal performs the retransmission.

Now, the method described inFIG.16will be described in further detail.

For a case in which a third party is involved in an L-pool (a first resource pool), a method of enabling the third party to select and propose a good resource different from existing terminals will be described. First, how the third party evaluates and proposes the good resource will be described.

The third party may perform a sensing operation to autonomously select a resource. For example, assume that the transmission resource selection(/reservation) is triggered in the subframe #m. In this case, the third party may select a resource for V2X signal transmission in a subframe period from subframes #m+T1 to #m+T2. The subframe period from the subframes #m+T1 to #m+T2 may be referred to as a selection window. For example, the selection window may be composed of 100 consecutive subframes.

In the selection window, the third party may select at least Y subframes as candidate resources. That is, in the selection window, the third party may have to consider at least Y subframes as candidate resources. The value of Y may be a preset value or a value that is set by a network. However, how to select the Y subframes in the selection window may be a problem of third party implementation. When the Y value is 50, for example, the third party may select/determine which 50 subframes will be selected among 100 subframes constituting the selection window through a sensing process (based on the sensing process).

In order to select (I reserve) a specific subframe among the Y subframes, for example, a subframe #N(SF #N) as a V2X transmission subframe capable of transmitting a V2X signal, the third party may have to sense linked to or associated with the subframe #N. An (entire) subframe period defined for sensing is referred to as a sensing window and may be composed of 1,000 subframes, for example. That is, the sensing window may be composed of 1000 milliseconds (ms) or 1 second. For example, in the sensing window, the third party may sense subframes corresponding to the subframe #N-100*k (where k may be a set of elements in the range [1, 10] and be a preset value or a value set by a network). For example, the third party may estimate/determine whether or not subframe #N is being used by another V2X terminal or whether or not there is an interference equal to or above a preset threshold (e.g., S-RSRP) by sensing the subframes #N-1000, #N-700, #N-500, #N-300, and #N-100 and may (finally) select subframe #N according to the result. The third party may perform such an operation to autonomously select a resource. Hereinafter, this method may also be referred to as a sensing-based resource occupancy/reservation method.

For a periodically transmitted message, the above-described sensing-based resource occupancy/reservation method may also be used in NR V2X. At least for a safety-related periodic message, the third party may perform a sensing operation in the same way as terminals and then may propose a selected resource to existing terminals.

When the third party proposes a resource, it may be more appropriate for the third party to perform unicast/groupcast than to broadcast information indicating the resource to a terminal. The reason is that when the third party proposes a selected resource to a terminal, it may be more efficient to propose the resource to a terminal having a link association in advance. For example, when the third party selects a good resource (for example, a resource having low interference) through a sensing operation, as information on the resource is broadcasted, the resource is used based on competition among terminals. At this time, when multiple terminals desire to occupy the informed resource for transmission simultaneously, there is no way of preventing collision.

When the third party attempts to propose a resource without establishing link association with a terminal, while broadcasting information on a selected resource through a sensing operation, the third party may also transmit information that the use of the resource is allowed under conditions that the priority and/or latency requirement and/or reliability of a packet to be sent by the terminal are equal to or greater than a specific value. In this way, a resource proposed by a third party is used not by every neighboring terminal but only by a specific service or terminal, and thus a probability of collision may be reduced.

On the other hand, when the third party proposes a resource, as the third party performs unicast or groupcast for information to indicate the resource to a terminal, a link association may be required in advance. The third party's link association with every neighboring terminal may be burdensome to implement. Accordingly, a category of terminals or a criterion of link association may be regulated to establish a link association with specifically limited terminals.

As an example, it is possible to establish a link association between a third party and terminals transmitting and receiving a specific service (e.g., terminals or a group supporting, transmitting and receiving a platooning service).

Alternatively, third party may periodically measure its peripheral channel (e.g., monitoring channel status through RSRP or RSSI measurement using received peripheral signals or performing CBR measurement) and allow a corresponding metric (e.g., RSRP, RSSL, and CBR) to have a link association with a terminal that is measured to be higher than a specific threshold. This operation may prevent a link association with an excessive number of terminals In addition, it may be advantageous for data transmission and reception since a link association may be established with terminals with strong reception power or close terminals.

There may be several solutions for a third party to identify a resource to be proposed. The simplest scheme is that the third party also performs an existing sensing and reservation scheme. However, this scheme of reservation after resource monitoring may be hard to apply to aperiodic traffic. It is because aperiodic traffic makes it difficult to predict an occurrence time of traffic or a traffic interval. Accordingly, for periodic traffic, a third party may propose a resource to terminals by performing an existing sensing and reservation scheme.

As for one possible problem caused by this scheme, since a third party senses a same channel in a same way as neighboring terminals, the proposal of a good resource (e.g., a resource with low interference) by the third party may become meaningless. Specifically, like other terminals, the third party also attempts to occupy a resource for an intra-cell V2X service and thus may be hardly eligible to propose a resource on behalf of the terminals. To solve this problem, the following solution may be applied.

1) A third party performs sensing in the same way as other terminals but may attempt to occupy a resource with a higher priority than the other terminals. Herein, the term “higher priority” may mean that a third party's transmission ProSe Per-Packet priority (PPPP) value actually has a high priority, or it may mean that a specific parameter (e.g., S-RSRP threshold, a parameter related to a ratio of a remaining set of selected resources among all the resource candidates) is set to be advantageous for the resource occupancy of the third party in a sensing process. As an example, when the transmission PPPP of a third party has a high value, a specific threshold for a corresponding resource in a sensing operation from the perspective of another terminal (e.g., a process of comparing S-RSRP with the specific threshold) may be set to be higher than before and thus be advantageous for the resource occupancy of the third party. That is, the third terminal having a higher priority than the first terminal and the second terminal, which are the parties to V2X communication, may first select a resource first within the first resource pool (L-pool) and then inform the first terminal of the selected resource through the recommendation information.

2) As another example, in case that top 20% resources are selected as a result of sensing process in a selection window, when the ratio is set to be higher for a third party, the effect obtained from the perspective of the third party may be that a resource is selected from more candidate sets. That is, when a third terminal performs a sensing operation in a sensing window and selects a first ratio of resources (e.g., top 20%) with good channel quality among resources in a selection window based on the sensing operation, the above-described recommendation information may propose/indicate the first ratio of resources to a first terminal. When the first terminal selects a second ratio of resources with good channel quality among the resources of the selection window based on a sensing operation, the first ratio may have a larger value than the second ratio.

3) When a sensing and reservation operation performed by a third party (hereinafter, a third terminal) is not advantageous enough to propose a resource, the third party may reserve a larger number of resources than other terminals. As an example, when up to 2 resources may be reserved for each terminal, 2 or more resources may be reserved for a third party (in order to occupy more resources to be proposed than other terminals). When the third party reserves an excessive number of resources, the reservation of the resources may be canceled and then the cancellation is reported to a base station so that the base station may utilize the resources for base station-based scheduling.

4) When a future channel condition is predicted, a third party may perform sensing and reservation ahead of other terminals and secure resources in advance. As an example, when a future channel condition becomes worse, for example, when entering a city area from a highway or a traffic jam is expected, a third party may occupy resources in advance by performing a sensing operation before a resource occupancy triggering time and reserving a sufficient number of resources. That is, the third terminal may perform a sensing operation and select a resource based on the sensing operation ahead of a first terminal and a second terminal and may inform the first terminal of the selected resources through the recommendation information.

5) When a third party is involved in the resource occupancy of other terminals (e.g., makes a proposal or recommendation), the third party may be so involved to avoid conflicts caused by randomness in the resource selection of each terminal. As an example, assume that a third party or terminals perform random selection among resources that are left after removing a resource occupied by another terminal. In this case, when the resource occupied by the other terminal is being removed, if the third party and the terminals have a same result of observation/measurement, the third party and the terminals would exclude a same resource from an entire set of resources (selection window). Next, a random selection may be made among the remaining resource candidates, and a conflict may occur as a result. To solve this problem, at least one of the following methods may be applied.

i) For a resource set to which a random selection is to be applied, a third party may determine an order of resources that each terminal will select. As an example, after a predefined ratio of resources (or subchannels) is left behind from an entire group of resource candidates through a sensing process, a random selection may be performed among the resources. Herein, terminals may select resources according to selection orders received from the third party. That is, the third party may (or may not) perform a sensing operation in the same way as terminals within a cell and may signal a selection order to each terminal. As an example, when 10 subchannels are left from all resource candidates according to a predefined ratio, the third party may indicate a resource selection order of 1, 2, 3, 4, . . . , 10 to a terminal1, a resource selection order of 10, 9, 8, 7, . . . , 1 to a terminal2and a resource selection order of 1, 3, 5, 7, 9, 2, 4, 6, 8, 10 to a terminal3. Herein, the term “selection order” may mean that candidate subchannels capable of being selected in a selection window may be ordered based on frequency first or time first. Each terminal may additionally use a resource according to such an order. This operation may reduce a probability of conflict.

ii) A selection order may be indicated by a third party, as described above, but may also be implemented by another method. As an example, an order of selected resources may be configured in advance so that it may be derived from a pseudo random sequence, and a third party may signal a seed value for it to a specific terminal. In this method, after every resource is set based on a pseudo random sequence, the seed value may be signaled and used for conflict control. Alternatively, while a specific resource is configured based on a pseudo random sequence, when a demand for an urgent message or a message with a high priority occurs, a third party may deliver a seed value to a corresponding terminal, thereby protecting the resource.

Hereinafter, a method for a third party to be generally involved in resource allocation and a resource allocation procedure will be proposed. Being generally involved may mean a case in which a message for a terminal within a cell to support a V2X service has an aperiodic pattern or a case of handing a sudden message (e.g., bursty data). Alternatively, it may be a case of handing a mixed message (e.g., periodic message+aperiodic message).

FIG.17illustrates an operation of each terminal in a wireless communication system including first, second, and third terminals.

Referring toFIG.17, first, consider a case in which resource allocation or involvement in resource allocation is triggered by a third party (or a third terminal) The third party may periodically broadcast a beacon or resource allocation triggering message (S171) A first terminal may transmit a resource allocation request message to the third party when it is determined to be within the coverage of the third party based on detection of a message transmitted by the third party (S172).

The third party may adjust the transmission power of the beacon or resource allocation triggering message to maintain or reduce its coverage. In addition, the resource allocation request message transmitted by the first terminal may be performed based on a transmission technique of initial access of NR Herein, the transmission technique means that an initial access process, entirely or partially, and a sequence of transmission signals included in the initial access process may be employed.

Alternatively, the first terminal may transmit a request message based on a competition like initial access and may configure the request message simply as ACK/NACK feedback. In this case, identity (ID) information of the terminal may be required to at least distinguish between terminals. Alternatively, in order to provide assistance and information for resource allocation to a third party, the first terminal may transmit the priority, a latency requirement, and reliability information of a packet to be transmitted when transmitting a resource allocation (RA) request message.

After receiving the resource allocation request message from the terminal through the above process, the third party (third terminal) may perform resource scheduling (S173) and then transmit grant message/recommendation information on it to the terminal (S174).

Herein, the resource scheduling method may be an existing sensing-based resource occupancy method or another scheduling method. For example, a carrier sense multiple access (CSMA)/collision avoidance (CA)-based resource allocation, a set grant scheduling method of NR, and the like may be possible.

The grant message for scheduling may include resource information for scheduling (e.g., the time and frequency of a resource, the number of allocated subchannels, MCS, CSI request, etc.).

After receiving a resource allocation request message from the first terminal through the above process, the third party may propose not grant information including explicit scheduling information but a good resource (e.g., resource with low interference) set (or pool) determined by the third party (or base station) through recommendation information.

As an example, a method in which the third party (or base station) determines a set of good resources may select a resource with low interference based on measurement (that is, S-RSRP, S-RSSI measurement) using a sensing technique. Alternatively, information on some resource pools among transmission resource pools may be proposed based on measurement, or a pool bitmap may be notified when signaling a pool configuration.

For the purpose of assisting the autonomous resource allocation of a resource, recommendation information (e.g., a bitmap of a group of recommended resource candidates, direct time of a recommended resource candidate, and frequency information) may be delivered.

Using the information (recommendation information or grant message) received from the third party, the first terminal performs sidelink communication with the second terminal (S175).

When the first terminal moves away from the third party, the first terminal may transmit a release request message for a corresponding resource or an information forwarding request message for the corresponding resource to the third party (or base station) (S176). As an example, whether the first terminal moves away from the third party may be determined by measuring a distance based on location information among messages (e.g., CAM message) received by the first terminal from the third terminal or by measuring reception power.

The purpose of transmitting the release message for the corresponding resource is to release the corresponding resource since the resource proposed by the third party is not guaranteed to be a good resource outside the coverage of the third party anymore. After releasing the resource, the first terminal may attempt resource allocation autonomously in a resource pool configured by a base station or may attempt resource allocation by utilizing an exceptional resource pool that is available for a specific purpose.

Resource release during message transmission may not be desirable for the transmission operation of the first terminal, and it may be necessary to maintain the resource when the message transmitted by the first terminal has a high priority. Accordingly, the first terminal may have to make the third party or a base station to forward information on the resource. Herein, the first terminal may transmit a forwarding request message including information on a resource to be forwarded (e.g., time/frequency information of the resource, a reservation interval, a priority, etc.) to the third party.

As described above, the third party may release a resource indicated by the release message received from the first terminal, and the released resource may be used for other terminals or be scheduled.

In the procedure above, as an example, when there is a mismatch between a resource allocated to the first terminal and actual message transmission timing or when excessive message transmission compared to the allocated resource is demanded, assistant information may be transmitted to the base station or reallocation of resources may be requested to the base station. Similarly, when a corresponding condition is satisfied, assistant information (e.g., estimated packet generation period/offset. PPPP, and a maximum packet size) may be transmitted to the third party or resource reallocation may be requested to the third party.

The process proposed above may be set to operate exclusively for a specific terminal. It is because there may be a mismatch of coverage between the third party and a specific terminal. For example, when the third party is an RSU-type stationary object, it may not be necessary for the third party to be involved in a terminal that moves from the third party at a high speed. Accordingly, a specific condition between the third party and a terminal may be needed. As an example, in an environment where there is an overlap of communication coverage between the third party and a terminal and (or) when the terminal drives at a low speed (e.g., at a speed of a specific distance per hour or less), and (or) when the terminal stays around the third party for over a specific time, the third party may be involved in resource allocation.

Hereinafter, a condition and method in which a third party is partially involved in scheduling of terminal will be described. It may be much burdensome for the third party to be involved in scheduling from the initial transmission of every terminal. To be involved in scheduling of every terminal, for example, a transmission power similar to a base station and intra-cell information need to be possessed. For this reason, it is possible for the third party to help neighboring terminals only with retransmission without being involved in every transmission scheduling.

As an example, terminals attempt to occupy an initial transmission resource by using an existing scheduling technique (that is, Rel-14 Mode 3, Mode 4 operation or NR Mode 1, 2 resource allocation operation) in first initial transmission. In initial transmission, a terminal may transmit assistant information for retransmission (e.g., packet generation period/offset, a packet priority, times required for retransmission, a maximum packet size, etc.) together with data to be transmitted. Then, the third party near the terminal may be involved in resource allocation only for HARQ retransmission resource by using the assistant information received from the terminal.

As an example, when receiving assistant information including a generation period set by 100 ms, times of necessary retransmission set by 2 and a packet priority set by A from a terminal, the third party may occupy resources for 2 times of necessary retransmission within 100 ms and signal information on the resources to a terminal transmitting the assistant information by using the above-proposed method or its own resource occupancy method. The above-described HARQ retransmission operation may be performed when a specific terminal is difficult to perform retransmission or has a burden of resource occupancy. However, in order to entrust an operation for every retransmission of every terminal to a third party, control/data information for retransmission may be set to be transmitted preferentially by a RSU and, when not being transmitted within a predetermined time, to be transmitted from an original transmission source.

As the examples of the proposal method described above may also be included in one of the implementation methods of the present disclosure, it is an obvious fact that they may be considered as a type of proposal methods In addition, the proposal methods described above may be implemented individually or in a combination (or merger) of some of them. A rule may be defined so that information on whether or not to apply the proposal methods (or information on the rules of the proposal methods) should be notified from a base station to a terminal or from a transmission terminal to a reception terminal through a predefined signal (e.g., a physical layer signal or an tipper layer signal).

FIG.18is a block diagram illustrating a terminal on which an embodiment of the present disclosure is implemented.

Referring toFIG.18, a terminal1100includes a processor1110, a memory1120, and a transceiver1130.

According to an embodiment, the processor111) may perform a function/an operation/a method described by the present disclosure. For example, the processor1110may control the first terminal so that the first terminal receives recommendation information recommending a resource available to V2X communication from a third terminal and performs the V2X communication with the second terminal by using a recommended resource that is determined based on the recommendation information.

The memory1120may store information/codes/instructions/measurements necessary for the operation of the terminal1100. The memory1120may be connected to the processor1110.

The transceiver1130transmits and receives radio signals by being connected with the processor1110.

The processor may include application-specific integrated circuit (SIC), another chipset, a logic circuit and/or a data processing device. The memory may include a read-only memory (ROM), a random access memory (RAM), a flash memory, a memory card, a storage medium and/or another storage device. A RF unit may include a base band circuit for processing radio signals. When an embodiment is implemented by software, the above-described technique may be implemented as a module (process, function, etc.) for performing the above-described function. The module may be stored in a memory and be run by a processor. The memory may be located either inside or outside the processor and be connected with the processor by various well-known means.

FIG.19is a block diagram of an example of a wireless communication device according to an embodiment of the present disclosure.

Referring toFIG.19, a wireless communication system may include a base station2210and UE (terminal)2220. The UE2220may be located within the region of the base station2210. In one scenario, the wireless communication system may include a plurality of UE. In the example ofFIG.19, the base station2210and the UE2220are illustrated but the present disclosure is not limited thereto. For example, the base station2210may be replaced by another network node. UE, a wireless device, or any other device.

The base station and the UE may be represented by a wireless communication device and a wireless device respectively. The base station ofFIG.19may be replaced by a network node, a wireless device or UE.

The base station2210may include at least one processor like the processor2211, at least one memory like the memory2212and at least one transceiver like the transceiver2213. The processor2211executes the above-described functions, procedures and/or methods. The processor2211may execute one or more protocols. For example, the processor2211may execute one or more lavers of a radio interface protocol. The memory2212is connected with the processor2211and stores various types of information and/or commands. The transceiver2213is connected with the processor2211and may be operated to transmit and receive radio signals.

The UE2220may include at least one processor like the processor2221, at least one memory like the memory2222and at least one transceiver like the transceiver2223.

The processor2221executes the above-described functions, procedures and/or methods. The processor2221may implement one or more protocols. For example, the processor2221may implement one or more layers of a radio interface protocol. The memory2222is connected with the processor2221and stores various types of information and/or commands. The transceiver2223is connected with the processor2221and may be operated to transmit and receive radio signals.

The memory2212and/or2222may be connected to the inside or outside of the processor2211and/or2221and be connected to another processor through various wired or wireless techniques.

The base station2210and/or the UE2220may have one or more antennas. For example, the antenna2214and/or2224may be configured to transmit and receive radio signals.

FIG.20shows an example of a wireless communication device according to an embodiment of the present disclosure.

FIG.20may be a view showing the UE2220ofFIG.19in detail. However, the wireless communication device ofFIG.20is not limited to the UE2220. The wireless communication device may be any appropriate mobile computer device configured to perform one or more implementations of the present disclosure, such as a vehicle communication system or device, a wearable device, a portable computer and a smartphone.

Referring toFIG.20, the UE2220may include at least one processor (e.g., DSP or microprocessor) like a processor2310, a transceiver2335, a power management module2305, an antenna2340, a battery2355, a display2315, a keypad2320, a global positioning system (GPS) chip2360, a sensor2365, a memory2330, a subscriber identity module (SIM) card2325(optional), a speaker2345, and a microphone2350. The UE2220may include one or more antennas.

The processor2310may be configured to execute the above-described functions, procedures and/or methods of the present disclosure. According to an implementation example, the processor2310may execute one or more protocols like layers of a radio interface protocol.

Being connected to the processor2310, the memory2330stores information on the operation of the processor2310. The memory2330may be located inside or outside the processor2314) and be connected to another processor through various wired or wireless techniques.

A user may input various types of information (e.g., command information like phone numbers) by pressing the buttons of the keypad2320or by using various techniques like voice activation using the microphone2350. The processor2310receives and processes the information of the user and executes an appropriate function like calling the phone number. As an example, data (e.g., operation data) may be retrieved from the SIM card2325or the memory2330to execute functions. As another example, in order to execute a function related to the location of UE like vehicle navigation and map service, the processor2310may receive GPS information from the GPS chip2360and process the information. As yet another example, for the user's reference or convenience, the processor2310may display various types of information and data on the display2315.

The transceiver2335is connected to the processor2310and transmits and receives a radio signal like RF signal. The processor2310may maneuver the transceiver2335so that the transceiver2335begins communication and transmits a radio signal including various types of information and data like voice communication data. The transceiver2335includes one receiver and one transmitter for receiving or transmitting radio signals. The antenna2340facilitates transmission and reception of radio signals According to an implementation example, when receiving radio signals, the transceiver2335may forward and covert the signals to a baseband frequency in order to process the signals by means of the processor2310. The processed signals may be processed according to various techniques like being converted to audible or readable information to be output through the speaker2345.

According to an implementation example, the sensor2365may be connected to the processor2310. The sensor2365may include one or more sensing devices configured to find various types of information that include velocity, acceleration, light, vibration, proximity, location and image but are not limited thereto. The processor2310may receive sensor information from the sensor2365and process the information and also perform various types of functions like collision avoidance and autonomous driving.

In the example ofFIG.20, various components (e.g., a camera, a USB port, etc.) may be further included in UE For example, a camera may be connected to the processor2310and be used for various services like autonomous driving and vehicle safety service.

Thus,FIG.20is only one example of UE and its implementation is not limited thereto. For example, some components (e.g., the keypad2320, the GPS chip2360, the sensor2365, the speaker2345and/or the microphone2350) may not be implemented in some scenarios.

FIG.21shows an example of a transceiver of a wireless communication device according to an embodiment of the present disclosure.

For example,FIG.21may show an example of a transceiver that may be implemented in a frequency division duplex (FDD) system.

In a transmission path, like the processors described mFIG.19andFIG.20, at least one processor may process data to be transmitted and also send a signal like an analog output signal to the transmitter2410.

In the above example, in order to remove noise caused by the previous analog-digital conversion (ADC), for example, the analog output signal in the transmitter2410is filtered by a low pass filter (LPF)2411, is upconverted from a base band to RF by an upconverter (e.g., mixer)2412, and is amplified by an amplifier like a variable gain amplifier (VGA)2413. The amplified signal is filtered by a filter2414, is amplified by a power amplifier (PA)2415, is routed through duplexer(s)2450/antenna switch(es)2460and is transmitted through an antenna2470.

In a reception path, the antenna2470receives signals in a wireless environment, and the received signals are routed by the antenna switch(es)2460/duplexer(s)2450and are sent to the receiver2420.

In the above example, the signal received in the receiver2420is amplified by an amplifier like a low noise amplifier (LNA)2423, is filtered by a band pass filter2424and is downconverted from RF to a base band by a down converter (e.g., mixer)2425.

The downconverted signal is filtered by a low pass filter (LPF)2426and is amplified by an amplifier like VGA2427to obtain an analog input signal. The analog input signal may be provided to one or more processors.

Furthermore, a local oscillator (LO)2440generates the transmission and reception of an LO signal and send it to the upconverter2412and the downconverter2425respectively.

According to an implementation example, a phase locked loop (PLL)2430may receive control information from the processor and provide control signals to an LO generator2440in order to generate the transmission and reception of LO signals at a suitable frequency.

Implementations are not limited to the specific layout illustrated inFIG.21, and various components and circuits may be arranged differently from the example ofFIG.21.

FIG.22shows another example of a transceiver of a wireless communication device according to an embodiment of the present disclosure.

For example,FIG.22may show an example of a transceiver that may be implemented in a time division duplex (TDD) system.

According to an implementation example, the transmitter2510and receiver2520of a transceiver of the TDD system may have one or more similar features to the transmitter and receiver of the transceiver of the FDD system. Hereinafter, the structure of the transceiver of the TDD system will be described.

In a transmission path, a signal amplified by a power amplifier (PA)2515of a transmitter is routed through a band selection switch2550, a band pass filter (BPF)2560and an antenna switch (or antenna switches)2570and is transmitted to an antenna2580.

In a reception path, the antenna2580received signals from a wireless environment, and the received signals are routed through the antenna switch(es)2570, the band pass filter (BPF)2560and the band selection switch2550and are provided to a receiver2520.

FIG.23illustrates a wireless device operation related to a sidelink.

The wireless device operation related to the sidelink described inFIG.23is mere illustrative, and sidelink operations using various techniques may be executed in a wireless device. A sidelink is a terminal-to-terminal interface for sidelink communication and/or sidelink discovery. A sidelink may correspond to a PC5 interface. In a broad sense, a sidelink operation may be the transmission and reception of information between terminals. A sidelink may deliver various types of information.

In the above example, the wireless device obtains sidelink-related information (S2910). The sidelink-related information may be one or more resource configurations. The sidelink-related information may be obtained from another wireless device or a network node.

After obtaining information, the wireless device decodes the sidelink-related information (S2920).

After decoding the sidelink-related information, the wireless device performs one or more sidelink operations based on the sidelink-related information (S2930). Here, the one or more sidelink operations performed by the wireless device may be one or more operations described herein.

FIG.24shows an example of operation of a network node related to a sidelink. The network node operation related to the sidelink described inFIG.24is mere illustrative, and sidelink operations using various techniques may be executed in a network node.

A network node receives information on a sidelink from a wireless device (S3010). For example, information on a sidelink may be ‘SindelinkTerminalInformation’ that is used to inform a network node of sidelink information.

After receiving the information, the network node determines whether or not to transmit one or more commands related to the sidelink based on the received information (S3020).

According to the determination of the network node to transmit a command, the network node transmits commands related to the sidelink to a wireless device (S3030). According to an implementation example, after receiving the command transmitted by the network node, the wireless device may perform one or more sidelink operations based on the received command.

FIG.25is a block diagram showing an implementation example of a wireless device3110and a network node3120. The network node3120may be replaced by a wireless device or a terminal.

In the above example, the wireless device3110includes a communication interface3111for communicating with one or more other wireless devices, network nodes and/or other components of a network. The communication interface3111may include one or more transmitters, one or more receivers and/or one or more communication interfaces. The wireless device3110includes a processing circuit3112. The processing circuit3112may include one or more processors like a processor3113and one or more memories like a memory3114.

The processing circuit3112may be configured to control any methods and/or processes described in this specification and/or, for example, to make the wireless device3110perform such a method and/or process. The processor3113corresponds to one or more processors for executing wireless device functions described in this specification. The wireless device3110includes the memory3114that is configured to store data, program software code and/or other information described in this specification.

According to an implementation example, the memory3114is configured to store a software code3115including a command that a processor3113should perform some or all the above-described processes according to the present disclosure, when one or more processors like the processor3113are operated.

For example, like the processor3113, one or more processors for running one or more transceivers like the transceiver2223to transmit and receive information may perform one or more processes related to the transmission and reception of information.

The network node3120includes a communication interface3121for communicating with one or more other network nodes, wireless devices and/or other components of a network. Herein, the communication interface3121includes one or more transmitters, one or more receivers and/or one or more communication interfaces. The network node3120includes the processing circuit3122. Herein, the processing circuit may include a processor3123and a memory3124.

According to an implementation example, when being operated by one or more processes like the processor3123, the memory3124is configured to store a software code3125including a command that a processor3123should perform some or all the above-described processes according to the present disclosure.

For example, like the processor3123, one or more processors for running one or more transceivers like the transceiver2213to transmit and receive information may perform one or more processes related to the transmission and reception of information.

The above-described implementation examples may be made by combining the structural elements and features of the present disclosure in various ways. Unless specified otherwise, each structural element or function may be selectively considered Each structural element or feature may be implemented without being combined with other structural elements or features. In addition, some structural elements and/or features may be combined with each other to configure the implementations of the present disclosure. An operation order described in an implementation of the present disclosure may be modified. Some structural elements or features of one implementation may be included in another implementation or be replaced by corresponding structural elements or features of the another implementation.

Implementations of the present disclosure may be made by various techniques, for example, hardware, firmware, software, or combinations thereof. In a hardware configuration, a method according to an implementation of the present disclosure may be performed by one or more application specific integrated circuits (ASICs), digital signal processing devices (DSPDs), programmable logic devices (PLDs), field programmable gate arrays (FPGAs), processors, controllers, microcontrollers and microprocessors.

In a configuration of firmware or software, implementations of the present disclosure may be made in a form of module, process, function, etc. A software code may be stored in a memory and be executed by a processor. A memory may be located inside or outside a processor and may transmit and receive data from a processor in various ways.

It is apparent to those skilled in the art that various changes and modifications may be made in the present disclosure without departing from the spirit or scope of the present disclosure.

The present disclosure has been described with reference to an example applied to a 3GPP LTE/LTE-A system or a 5G system (NR system) but is also applicable to various other wireless communication systems.

Each order of the flowchart is only an example, and the flowchart may be implemented in a different order from the order illustrated in the drawing.

FIG.26illustrates a communication system (1), in accordance with an embodiment of the present disclosure.

The wireless devices100ato100fmay be connected to the network300via the BSs200. An AI technology may be applied to the wireless devices100a˜100f) and the wireless devices100ato100fmay be connected to the AI server400via the network300. The network30) may be configured using a 3G network, a 4G (e.g., LTE) network, or a 5G (e.g., NR) network. Although the wireless devices100ato100fmay communicate with each other through the BSs200/network300, the wireless devices100a-100f) may perform direct communication (e.g., sidelink communication) with each other without passing through the BSs/network. For example, the vehicles100b-land100b-2may perform direct communication (e.g., Vehicle-to-Vehicle (V2V)/Vehicle-to-everything (V2X) communication). The IoT device (e.g., a sensor) may perform direct communication with other IoT devices (e.g., sensors) or other wireless devices100ato100f.

FIG.27illustrates wireless devices, in accordance with an embodiment of the present disclosure.

Referring toFIG.27, a first wireless device100and a second wireless device200may transmit radio signals through various RATs (e.g., LTE and NR). Herein, {the first wireless device100and the second wireless device200} may correspond to {the wireless device100xand the BS200} and/or {the wireless device100xand the wireless device100x} ofFIG.26.

FIG.28illustrates a signal process circuit for a transmission signal, in accordance with an embodiment of the present disclosure.

Referring toFIG.28, a signal processing circuit1000may include scramblers1010, modulators1020, a layer mapper1030, a precoder1040, resource mappers1050, and signal generators1060. An operation/function ofFIG.28may be performed, without being limited to, the processors102and202and/or the transceivers106and206ofFIG.27. Hardware elements ofFIG.28may be implemented by the processors102and202and/or the transceivers106and206ofFIG.27. For example, blocks1010to1060may be implemented by the processors102and202ofFIG.27. Alternatively, the blocks1010to1050may be implemented by the processors102and202ofFIG.27and the block1060may be implemented by the transceivers106and206ofFIG.27.

FIG.29illustrates another example of a wireless device, in accordance with an embodiment of the present disclosure. The wireless device may be implemented in various forms according to a use-case/service (refer toFIG.26).

The additional components140may be variously configured according to types of wireless devices. For example, the additional components140may include at least one of a power unit/battery, input/output (I/O) unit, a driving unit, and a computing unit. The wireless device may be implemented in the form of, without being limited to, the robot100aofFIG.26, the vehicles100b-1and100b-2ofFIG.26, the XR device100cofFIG.26, the hand-held device100dofFIG.26, the home appliance100eofFIG.26, the IoT device100fofFIG.26, a digital broadcast terminal, a hologram device, a public safety device, an MTC device, a medicine device, a fintech device (or a finance device), a security device, a climate/environment device, the AI server/device400ofFIG.26, the BSs200ofFIG.26, a network node, etc. The wireless device may be used in a mobile or fixed place according to a use-example/service.

Hereinafter, an example of implementingFIG.29will be described in detail with reference to the drawings.

As the examples of the proposal method described above may also be included in one of the implementation methods of the present disclosure, it is an obvious fact that they may be considered as a type of proposal methods. In addition, the proposal methods described above may be implemented individually or in a combination (or merger) of some of them. A rule may be defined so that information on whether or not to apply the proposal methods (or information on the rules of the proposal methods) should be notified from a base station to a terminal or from a transmission terminal to a reception terminal through a predefined signal (e.g., a physical layer signal (e.g., signaling through PDCCH/PDSCH) or an upper layer signal (e.g., RRC)).

Claims in the present description can be combined in various ways. For instance, technical features in method claims of the present description can be combined to be implemented or performed in an apparatus, and technical features in apparatus claims can be combined to be implemented or performed in a method. Further, technical features in method claim(s) and apparatus claim(s) can be combined to be implemented or performed in an apparatus. Further, technical features in method claim(s) and apparatus claim(s) can be combined to be implemented or performed in a method.