Patent Description:
Wireless communication systems are being widely deployed to provide various types of communication services such as voice and data. In general, a wireless communication system is a multiple access system capable of supporting communication with multiple users by sharing available system resources (bandwidth, transmission power, etc.). Examples of the multiple access system include a code division multiple access (CDMA) system, a frequency division multiple access (FDMA) system, a time division multiple access (TDMA) system, an orthogonal frequency division multiple access (OFDMA) system, and a single carrier frequency division multiple access (SC-FDMA) system, and a multi carrier frequency division multiple access (MC-FDMA) system.

A wireless communication system uses various radio access technologies (RATs) such as long term evolution (LTE), LTE-advanced (LTE-A), and wireless fidelity (WiFi). 5th generation (<NUM>) is such a wireless communication system. Three key requirement areas of <NUM> include (<NUM>) enhanced mobile broadband (eMBB), (<NUM>) massive machine type communication (mMTC), and (<NUM>) ultra-reliable and low latency communications (URLLC). Some use cases may require multiple dimensions for optimization, while others may focus only on one key performance indicator (KPI). <NUM> supports such diverse use cases in a flexible and reliable way.

eMBB goes far beyond basic mobile Internet access and covers rich interactive work, media and entertainment applications in the cloud or augmented reality (AR). Data is one of the key drivers for <NUM> and in the <NUM> era, we may for the first time see no dedicated voice service. In <NUM>, voice is expected to be handled as an application program, simply using data connectivity provided by a communication system. The main drivers for an increased traffic volume are the increase in the size of content and the number of applications requiring high data rates. Streaming services (audio and video), interactive video, and mobile Internet connectivity will continue to be used more broadly as more devices connect to the Internet. Many of these applications require always-on connectivity to push real time information and notifications to users. Cloud storage and applications are rapidly increasing for mobile communication platforms. This is applicable for both work and entertainment. Cloud storage is one particular use case driving the growth of uplink data rates. <NUM> will also be used for remote work in the cloud which, when done with tactile interfaces, requires much lower end-to-end latencies in order to maintain a good user experience. Entertainment, for example, cloud gaming and video streaming, is another key driver for the increasing need for mobile broadband capacity. Entertainment will be very essential on smart phones and tablets everywhere, including high mobility environments such as trains, cars and airplanes. Another use case is augmented reality (AR) for entertainment and information search, which requires very low latencies and significant instant data volumes.

One of the most expected <NUM> use cases is the functionality of actively connecting embedded sensors in every field, that is, mMTC. It is expected that there will be <NUM> billion potential Internet of things (IoT) devices by <NUM>. In industrial IoT, <NUM> is one of areas that play key roles in enabling smart city, asset tracking, smart utility, agriculture, and security infrastructure.

URLLC includes services which will transform industries with ultra-reliable/available, low latency links such as remote control of critical infrastructure and self-driving vehicles. The level of reliability and latency are vital to smart-grid control, industrial automation, robotics, drone control and coordination, and so on.

Now, multiple use cases will be described in detail.

<NUM> may complement fiber-to-the home (FTTH) and cable-based broadband (or data-over-cable service interface specifications (DOCSIS)) as a means of providing streams at data rates of hundreds of megabits per second to giga bits per second. Such a high speed is required for TV broadcasts at or above a resolution of <NUM> (<NUM>, <NUM>, and higher) as well as virtual reality (VR) and AR. VR and AR applications mostly include immersive sport games. A special network configuration may be required for a specific application program. For VR games, for example, game companies may have to integrate a core server with an edge network server of a network operator in order to minimize latency.

The automotive sector is expected to be a very important new driver for <NUM>, with many use cases for mobile communications for vehicles. For example, entertainment for passengers requires simultaneous high capacity and high mobility mobile broadband, because future users will expect to continue their good quality connection independent of their location and speed. Other use cases for the automotive sector are AR dashboards. These display overlay information on top of what a driver is seeing through the front window, identifying objects in the dark and telling the driver about the distances and movements of the objects. In the future, wireless modules will enable communication between vehicles themselves, information exchange between vehicles and supporting infrastructure and between vehicles and other connected devices (e.g., those carried by pedestrians). Safety systems may guide drivers on alternative courses of action to allow them to drive more safely and lower the risks of accidents. The next stage will be remote-controlled or self-driving vehicles. These require very reliable, very fast communication between different self-driving vehicles and between vehicles and infrastructure. In the future, self-driving vehicles will execute all driving activities, while drivers are focusing on traffic abnormality elusive to the vehicles themselves. The technical requirements for self-driving vehicles call for ultra-low latencies and ultra-high reliability, increasing traffic safety to levels humans cannot achieve.

Smart cities and smart homes, often referred to as smart society, will be embedded with dense wireless sensor networks. Distributed networks of intelligent sensors will identify conditions for cost- and energy-efficient maintenance of the city or home. A similar setup can be done for each home, where temperature sensors, window and heating controllers, burglar alarms, and home appliances are all connected wirelessly. Many of these sensors are typically characterized by low data rate, low power, and low cost, but for example, real time high definition (HD) video may be required in some types of devices for surveillance.

The consumption and distribution of energy, including heat or gas, is becoming highly decentralized, creating the need for automated control of a very distributed sensor network. A smart grid interconnects such sensors, using digital information and communications technology to gather and act on information. This information may include information about the behaviors of suppliers and consumers, allowing the smart grid to improve the efficiency, reliability, economics and sustainability of the production and distribution of fuels such as electricity in an automated fashion. A smart grid may be seen as another sensor network with low delays.

The health sector has many applications that may benefit from mobile communications. Communications systems enable telemedicine, which provides clinical health care at a distance. It helps eliminate distance barriers and may improve access to medical services that would often not be consistently available in distant rural communities. It is also used to save lives in critical care and emergency situations. Wireless sensor networks based on mobile communication may provide remote monitoring and sensors for parameters such as heart rate and blood pressure.

Wireless and mobile communications are becoming increasingly important for industrial applications. Wires are expensive to install and maintain, and the possibility of replacing cables with reconfigurable wireless links is a tempting opportunity for many industries. However, achieving this requires that the wireless connection works with a similar delay, reliability and capacity as cables and that its management is simplified. Low delays and very low error probabilities are new requirements that need to be addressed with <NUM>.

Finally, logistics and freight tracking are important use cases for mobile communications that enable the tracking of inventory and packages wherever they are by using location-based information systems. The logistics and freight tracking use cases typically require lower data rates but need wide coverage and reliable location information.

A wireless communication system is a multiple access system that supports communication of multiple users by sharing available system resources (a bandwidth, transmission power, etc.). Examples of multiple access systems include a CDMA system, an FDMA system, a TDMA system, an OFDMA system, an SC-FDMA system, and an MC-FDMA system.

Sidelink (SL) refers to a communication scheme in which a direct link is established between user equipments (UEs) and the UEs directly exchange voice or data without intervention of a base station (BS). SL is considered as a solution of relieving the BS of the constraint of rapidly growing data traffic.

Vehicle-to-everything (V2X) is a communication technology in which a vehicle exchanges information with another vehicle, a pedestrian, and infrastructure by wired/wireless communication. V2X may be categorized into four types: vehicle-to-vehicle (V2V), vehicle-to-infrastructure (V2I), vehicle-to-network (V2N), and vehicle-to-pedestrian (V2P). V2X communication may be provided via a PC5 interface and/or a Uu interface.

As more and more communication devices demand larger communication capacities, there is a need for enhanced mobile broadband communication relative to existing RATs. Accordingly, a communication system is under discussion, for which services or UEs sensitive to reliability and latency are considered. The next-generation RAT in which eMBB, MTC, and URLLC are considered is referred to as new RAT or NR. In NR, V2X communication may also be supported.

<FIG> is a diagram illustrating V2X communication based on pre-NR RAT and V2X communication based on NR in comparison.

For V2X communication, a technique of providing safety service based on V2X messages such as basic safety message (BSM), cooperative awareness message (CAM), and decentralized environmental notification message (DENM) was mainly discussed in the pre-NR RAT. The V2X message may include location information, dynamic information, and attribute information. For example, a UE may transmit a CAM of a periodic message type and/or a DENM of an event-triggered type to another UE.

For example, the CAM may include basic vehicle information including dynamic state information such as a direction and a speed, vehicle static data such as dimensions, an external lighting state, path details, and so on. For example, the UE may broadcast the CAM which may have a latency less than <NUM>. For example, when an unexpected incident occurs, such as breakage or an accident of a vehicle, the UE may generate the DENM and transmit the DENM to another UE. For example, all vehicles within the transmission range of the UE may receive the CAM and/or the DENM. In this case, the DENM may have priority over the CAM.

In relation to V2X communication, various V2X scenarios are presented in NR. For example, the V2X scenarios include vehicle platooning, advanced driving, extended sensors, and remote driving.

For example, vehicles may be dynamically grouped and travel together based on vehicle platooning. For example, to perform platoon operations based on vehicle platooning, the vehicles of the group may receive periodic data from a leading vehicle. For example, the vehicles of the group may widen or narrow their gaps based on the periodic data.

For example, a vehicle may be semi-automated or full-automated based on advanced driving. For example, each vehicle may adjust a trajectory or maneuvering based on data obtained from a nearby vehicle and/or a nearby logical entity. For example, each vehicle may also share a dividing intention with nearby vehicles.

Based on extended sensors, for example, raw or processed data obtained through local sensor or live video data may be exchanged between vehicles, logical entities, terminals of pedestrians and/or V2X application servers. Accordingly, a vehicle may perceive an advanced environment relative to an environment perceivable by its sensor.

Based on remote driving, for example, a remote driver or a V2X application may operate or control a remote vehicle on behalf of a person incapable of driving or in a dangerous environment. For example, when a path may be predicted as in public transportation, cloud computing-based driving may be used in operating or controlling the remote vehicle. For example, access to a cloud-based back-end service platform may also be used for remote driving.

A scheme of specifying service requirements for various V2X scenarios including vehicle platooning, advanced driving, extended sensors, and remote driving is under discussion in NR-based V2X communication.

Prior art can be found in, e.g., Huawei et al, R1-<NUM>, which generally relates to "Sidelink physical layer structure for NR V2X".

An object of embodiment(s) is methods of generating/mapping/transmitting a PTRS in sidelink.

According to an embodiment, a method of transmitting a phase-tracking reference signal (PTRS) related to sidelink by a user equipment (UE) in a wireless communication system includes generating a demodulation reference signals (DMRS) related to a physical sidelink shared channel (PSSCH), generating the PTRS related to the PSSCH, and transmitting at least a portion of the DMRS and the PTRS, wherein: a resource region of a physical sidelink control channel, PSCCH, overlaps with at least a part of a resource region of the PSSCH, a DMRS sequence mapped to a predetermined position in a first PSSCH symbol in which the DMRS is transmitted is used to generate the PTRS, the predetermined position corresponds to a frequency position at which the PTRS is transmitted, and the predetermined position includes a frequency position at which transmission of the generated DMRS is skipped.

According to an example, a user equipment (UE) for transmitting a phase-tracking reference signal (PTRS) in a wireless communication system includes at least one processor, and at least one computer memory operatively connected to the at least one processor and configured to store commands for allowing the at least one processor to perform operations when being executed, wherein the operations includes generating a demodulation reference signals (DMRS) related to a physical sidelink shared channel (PSSCH), generating the PTRS related to the PSSCH, and transmitting at least a portion of the DMRS and the PTRS, wherein a DMRS sequence mapped to a predetermined position in a first PSSCH symbol in which the DMRS is transmitted is used to generate the PTRS, the predetermined position corresponds to a frequency position at which the PTRS is transmitted, and the predetermined position includes a frequency position at which transmission of the generated DMRS is skipped.

According to an embodiment, a processor for performing operations for a user equipment (UE) for transmitting a phase-tracking reference signal (PTRS) in a wireless communication system includes generating a demodulation reference signals (DMRS) related to a physical sidelink shared channel (PSSCH), generating the PTRS related to the PSSCH, and transmitting at least a portion of the DMRS and the PTRS, wherein: a resource region of a physical sidelink control channel, PSCCH, overlaps with at least a part of a resource region of the PSSCH, a DMRS sequence mapped to a predetermined position in a first PSSCH symbol in which the DMRS is transmitted is used to generate the PTRS, the predetermined position corresponds to a frequency position at which the PTRS is transmitted, and the predetermined position includes a frequency position at which transmission of the generated DMRS is skipped.

An embodiment provides a non-volatile computer-readable recording medium for storing at least one computer program including a command for allowing at least one processor to perform operations of a user equipment (UE) when being executed by the at least one processor, the operations including generating a demodulation reference signals (DMRS) related to a physical sidelink shared channel (PSSCH), generating the PTRS related to the PSSCH, and transmitting at least a portion of the DMRS and the PTRS, wherein: a resource region of a physical sidelink control channel, PSCCH, overlaps with at least a part of a resource region of the PSSCH, a DMRS sequence mapped to a predetermined position in a first PSSCH symbol in which the DMRS is transmitted is used to generate the PTRS, the predetermined position corresponds to a frequency position at which the PTRS is transmitted, and the predetermined position includes a frequency position at which transmission of the generated DMRS is skipped.

Based on that a resource region of a physical sidelink control channel (PSCCH) entirely overlaps with a resource region of the PSSCH, the first PSSCH symbol in which the DMRS is transmitted may be a symbol in which the DMRS is transmitted first after the resource region of the PSCCH.

The PSSCH and the PSCCH may be frequency division multiplexed (FDM) in a time axis corresponding to the first PSSCH symbol.

The frequency position may be a subcarrier.

Transmission of the PTRS may be skipped when the PTRS overlaps with the PSCCH.

The UE may communicate with at least one of another UE, a UE related to autonomous driving vehicle, a base station (BS), or a network.

An embodiment may overcome the ambiguity of a method of generating a PTRS in an overlapping period with a PSCCH when the PTRS is generated based on a DMRS.

In various embodiments of the present disclosure, "/" and "," should be interpreted as "and/or". Further, "A, B" may mean "A and/or B". Further, "A/B/C" may mean "at least one of A, B and/or C". Further, "A, B, C" may mean "at least one of A, B and/or C".

In various embodiments of the present disclosure, "or" should be interpreted as "and/or". For example, "A or B" may include "only A", "only B", and/or "both A and B". In other words, "or" should be interpreted as "additionally or alternatively".

Techniques described herein may be used in various wireless access systems such as code division multiple access (CDMA), frequency division multiple access (FDMA), time division multiple access (TDMA), orthogonal frequency division multiple access (OFDMA), single carrier-frequency division multiple access (SC-FDMA), and so on. CDMA may be implemented as a radio technology such as universal terrestrial radio access (UTRA) or CDMA2000. TDMA may be implemented as a radio technology such as global system for mobile communications (GSM)/general packet radio service (GPRS)/Enhanced Data Rates for GSM Evolution (EDGE). OFDMA may be implemented as a radio technology such as IEEE <NUM> (Wi-Fi), IEEE <NUM> (WiMAX), IEEE <NUM>, evolved-UTRA (E-UTRA), or the like. IEEE <NUM> is an evolution of IEEE <NUM>. 16e, offering backward compatibility with an IRRR <NUM>. 16e-based system. UTRA is a part of universal mobile telecommunications system (UMTS). 3rd generation partnership project (3GPP) long term evolution (LTE) is a part of evolved UMTS (E-UMTS) using evolved UTRA (E-UTRA). 3GPP LTE employs OFDMA for downlink (DL) and SC-FDMA for uplink (UL). LTE-advanced (LTE-A) is an evolution of 3GPP LTE.

A successor to LTE-A, <NUM>th generation (<NUM>) new radio access technology (NR) is a new clean-state mobile communication system characterized by high performance, low latency, and high availability. <NUM> NR may use all available spectral resources including a low frequency band below <NUM>, an intermediate frequency band between <NUM> and <NUM>, and a high frequency (millimeter) band of <NUM> or above.

While the following description is given mainly in the context of LTE-A or <NUM> NR for the clarity of description, the technical idea of an embodiment of the present disclosure is not limited thereto.

<FIG> illustrates the structure of an LTE system according to an embodiment of the present disclosure. This may also be called an evolved UMTS terrestrial radio access network (E-UTRAN) or LTE/LTE-A system.

Referring to <FIG>, the E-UTRAN includes evolved Node Bs (eNBs) <NUM> which provide a control plane and a user plane to UEs <NUM>. A UE <NUM> may be fixed or mobile, and may also be referred to as a mobile station (MS), user terminal (UT), subscriber station (SS), mobile terminal (MT), or wireless device. An eNB <NUM> is a fixed station communication with the UE <NUM> and may also be referred to as a base station (BS), a base transceiver system (BTS), or an access point.

eNBs <NUM> may be connected to each other via an X2 interface. An eNB <NUM> is connected to an evolved packet core (EPC) <NUM> via an S1 interface. More specifically, the eNB <NUM> is connected to a mobility management entity (MME) via an S1-MME interface and to a serving gateway (S-GW) via an S1-U interface.

The EPC <NUM> includes an MME, an S-GW, and a packet data network-gateway (P-GW). The MME has access information or capability information about UEs, which are mainly used for mobility management of the UEs. The S-GW is a gateway having the E-UTRAN as an end point, and the P-GW is a gateway having a packet data network (PDN) as an end point.

Based on the lowest three layers of the open system interconnection (OSI) reference model known in communication systems, the radio protocol stack between a UE and a network may be divided into Layer <NUM> (L1), Layer <NUM> (L2) and Layer <NUM> (L3). These layers are defined in pairs between a UE and an Evolved UTRAN (E-UTRAN), for data transmission via the Uu interface. The physical (PHY) layer at L1 provides an information transfer service on physical channels. The radio resource control (RRC) layer at L3 functions to control radio resources between the UE and the network. For this purpose, the RRC layer exchanges RRC messages between the UE and an eNB.

<FIG> illustrates a user-plane radio protocol architecture according to an embodiment of the disclosure.

<FIG> illustrates a control-plane radio protocol architecture according to an embodiment of the disclosure. A user plane is a protocol stack for user data transmission, and a control plane is a protocol stack for control signal transmission.

Referring to <FIG>, the PHY layer provides an information transfer service to its higher layer on physical channels. The PHY layer is connected to the medium access control (MAC) layer through transport channels and data is transferred between the MAC layer and the PHY layer on the transport channels. The transport channels are divided according to features with which data is transmitted via a radio interface.

Data is transmitted on physical channels between different PHY layers, that is, the PHY layers of a transmitter and a receiver. The physical channels may be modulated in orthogonal frequency division multiplexing (OFDM) and use time and frequencies as radio resources.

The MAC layer provides services to a higher layer, radio link control (RLC) on logical channels. The MAC layer provides a function of mapping from a plurality of logical channels to a plurality of transport channels. Further, the MAC layer provides a logical channel multiplexing function by mapping a plurality of logical channels to a single transport channel. A MAC sublayer provides a data transmission service on the logical channels.

The RLC layer performs concatenation, segmentation, and reassembly for RLC serving data units (SDUs). In order to guarantee various quality of service (QoS) requirements of each radio bearer (RB), the RLC layer provides three operation modes, transparent mode (TM), unacknowledged mode (UM), and acknowledged Mode (AM). An AM RLC provides error correction through automatic repeat request (ARQ).

The RRC layer is defined only in the control plane and controls logical channels, transport channels, and physical channels in relation to configuration, reconfiguration, and release of RBs. An RB refers to a logical path provided by L1 (the PHY layer) and L2 (the MAC layer, the RLC layer, and the packet data convergence protocol (PDCP) layer), for data transmission between the UE and the network.

The user-plane functions of the PDCP layer include user data transmission, header compression, and ciphering. The control-plane functions of the PDCP layer include control-plane data transmission and ciphering/integrity protection.

RB establishment amounts to a process of defining radio protocol layers and channel features and configuring specific parameters and operation methods in order to provide a specific service. RBs may be classified into two types, signaling radio bearer (SRB) and data radio bearer (DRB). The SRB is used as a path in which an RRC message is transmitted on the control plane, whereas the DRB is used as a path in which user data is transmitted on the user plane.

Once an RRC connection is established between the RRC layer of the UE and the RRC layer of the E-UTRAN, the UE is placed in RRC_CONNECTED state, and otherwise, the UE is placed in RRC_IDLE state. In NR, RRC_INACTIVE state is additionally defined. A UE in the RRC_INACTIVE state may maintain a connection to a core network, while releasing a connection from an eNB.

DL transport channels carrying data from the network to the UE include a broadcast channel (BCH) on which system information is transmitted and a DL shared channel (DL SCH) on which user traffic or a control message is transmitted. Traffic or a control message of a DL multicast or broadcast service may be transmitted on the DL-SCH or a DL multicast channel (DL MCH). UL transport channels carrying data from the UE to the network include a random access channel (RACH) on which an initial control message is transmitted and an UL shared channel (UL SCH) on which user traffic or a control message is transmitted.

The logical channels which are above and mapped to the transport channels include a broadcast control channel (BCCH), a paging control channel (PCCH), a common control channel (CCCH), a multicast control channel (MCCH), and a multicast traffic channel (MTCH).

A physical channel includes a plurality of OFDM symbol in the time domain by a plurality of subcarriers in the frequency domain. One subframe includes a plurality of OFDM symbols in the time domain. An RB is a resource allocation unit defined by a plurality of OFDM symbols by a plurality of subcarriers. Further, each subframe may use specific subcarriers of specific OFDM symbols (e.g., the first OFDM symbol) in a corresponding subframe for a physical DL control channel (PDCCH), that is, an L1/L2 control channel. A transmission time interval (TTI) is a unit time for subframe transmission.

<FIG> illustrates the structure of an NR system according to an embodiment of the present disclosure.

Referring to <FIG>, a next generation radio access network (NG-RAN) may include a next generation Node B (gNB) and/or an eNB, which provides user-plane and control-plane protocol termination to a UE. In <FIG>, the NG-RAN is shown as including only gNBs, by way of example. A gNB and an eNB are connected to each other via an Xn interface. The gNB and the eNB are connected to a <NUM> core network (5GC) via an NG interface. More specifically, the gNB and the eNB are connected to an access and mobility management function (AMF) via an NG-C interface and to a user plane function (UPF) via an NG-U interface.

<FIG> illustrates functional split between the NG-RAN and the 5GC according to an embodiment of the present disclosure.

Referring to <FIG>, a gNB may provide functions including inter-cell radio resource management (RRM), radio admission control, measurement configuration and provision, and dynamic resource allocation. The AMF may provide functions such as non-access stratum (NAS) security and idle-state mobility processing. The UPF may provide functions including mobility anchoring and protocol data unit (PDU) processing. A session management function (SMF) may provide functions including UE Internet protocol (IP) address allocation and PDU session control.

<FIG> illustrates a radio frame structure in NR, to which embodiment(s) of the present disclosure is applicable.

Referring to <FIG>, a radio frame may be used for UL transmission and DL transmission in NR. A radio frame is <NUM> in length, and may be defined by two <NUM>-ms half-frames. An HF may include five <NUM>-ms subframes. A subframe may be divided into one or more slots, and the number of slots in an SF may be determined according to a subcarrier spacing (SCS).

In a normal CP (NCP) case, each slot may include <NUM> symbols, whereas in an extended CP (ECP) case, each slot may include <NUM> symbols. Herein, a symbol may be an OFDM symbol (or CP-OFDM symbol) or an SC-FDMA symbol (or DFT-s-OFDM symbol).

Table <NUM> below lists the number of symbols per slot Nslotsymb, the number of slots per frame Nframe,uslot, and the number of slots per subframe Nsubframe,uslot according to an SCS configuration µ in the NCP case.

Table <NUM> below lists the number of symbols per slot, the number of slots per frame, and the number of slots per subframe according to an SCS in the ECP case.

In the NR system, different OFDM(A) numerologies (e.g., SCSs, CP lengths, and so on) may be configured for a plurality of cells aggregated for one UE. Accordingly, the (absolute time) duration of a time resource including the same number of symbols (e.g., a subframe, slot, or TTI) (collectively referred to as a time unit (TU) for convenience) may be configured to be different for the aggregated cells.

In NR, various numerologies or SCSs may be supported to support various <NUM> services. For example, with an SCS of <NUM>, a wide area in traditional cellular bands may be supported, while with an SCS of <NUM>/<NUM>, a dense urban area, a lower latency, and a wide carrier bandwidth may be supported. With an SCS of <NUM> or higher, a bandwidth larger than <NUM> may be supported to overcome phase noise.

An NR frequency band may be defined by two types of frequency ranges, FR1 and FR2. The numerals in each frequency range may be changed. For example, the two types of frequency ranges may be given in Table <NUM>. In the NR system, FR1 may be a "sub <NUM> range" and FR2 may be an "above <NUM> range" called millimeter wave (mmW).

As mentioned above, the numerals in a frequency range may be changed in the NR system. For example, FR1 may range from <NUM> to <NUM> as listed in Table <NUM>. That is, FR1 may include a frequency band of <NUM> (or <NUM>, <NUM>, and <NUM>) or above. For example, the frequency band of <NUM> (or <NUM>, <NUM>, and <NUM>) or above may include an unlicensed band. The unlicensed band may be used for various purposes, for example, vehicle communication (e.g., autonomous driving).

<FIG> illustrates a slot structure in an NR frame according to an embodiment of the present disclosure.

Referring to <FIG>, a slot includes a plurality of symbols in the time domain. For example, one slot may include <NUM> symbols in an NCP case and <NUM> symbols in an ECP case. Alternatively, one slot may include <NUM> symbols in an NCP case and <NUM> symbols in an ECP case.

A carrier includes a plurality of subcarriers in the frequency domain. An RB may be defined by a plurality of (e.g., <NUM>) consecutive subcarriers in the frequency domain. A bandwidth part (BWP) may be defined by a plurality of consecutive (physical) RBs ((P)RBs) in the frequency domain and correspond to one numerology (e.g., SCS, CP length, or the like). A carrier may include up to N (e.g., <NUM>) BWPs. Data communication may be conducted in an activated BWP. Each element may be referred to as a resource element (RE) in a resource grid, to which one complex symbol may be mapped.

A radio interface between UEs or a radio interface between a UE and a network may include L1, L2, and L3. In various embodiments of the present disclosure, L1 may refer to the PHY layer. For example, L2 may refer to at least one of the MAC layer, the RLC layer, the PDCH layer, or the SDAP layer. For example, L3 may refer to the RRC layer.

Now, a description will be given of sidelink (SL) communication.

<FIG> illustrates a radio protocol architecture for SL communication according to an embodiment of the present disclosure. Specifically, <FIG> illustrates a user-plane protocol stack in LTE, and <FIG> illustrates a control-plane protocol stack in LTE.

<FIG> illustrates a radio protocol architecture for SL communication according to an embodiment of the present disclosure. Specifically, <FIG> illustrates a user-plane protocol stack in NR, and <FIG> illustrates a control-plane protocol stack in NR.

Resource allocation in SL will be described below.

<FIG> illustrates a procedure of performing V2X or SL communication according to a transmission mode in a UE according to an embodiment of the present disclosure. In various embodiments of the present disclosure, a transmission mode may also be referred to as a mode or a resource allocation mode. For the convenience of description, a transmission mode in LTE may be referred to as an LTE transmission mode, and a transmission mode in NR may be referred to as an NR resource allocation mode.

For example, <FIG> illustrates a UE operation related to LTE transmission mode <NUM> or LTE transmission mode <NUM>. Alternatively, for example, <FIG> illustrates a UE operation related to NR resource allocation mode <NUM>. For example, LTE transmission mode <NUM> may be applied to general SL communication, and LTE transmission mode <NUM> may be applied to V2X communication.

For example, <FIG> illustrates a UE operation related to LTE transmission mode <NUM> or LTE transmission mode <NUM>. Alternatively, for example, <FIG> illustrates a UE operation related to NR resource allocation mode <NUM>.

Referring to <FIG>, in LTE transmission mode <NUM>, LTE transmission mode <NUM>, or NR resource allocation mode <NUM>, a BS may schedule SL resources to be used for SL transmission of a UE. For example, the BS may perform resource scheduling for UE1 through a PDCCH (more specifically, DL control information (DCI)), and UE1 may perform V2X or SL communication with UE2 according to the resource scheduling. For example, UE1 may transmit sidelink control information (SCI) to UE2 on a PSCCH, and then transmit data based on the SCI to UE2 on a PSSCH.

For example, in NR resource allocation mode <NUM>, a UE may be provided with or allocated resources for one or more SL transmissions of one transport block (TB) by a dynamic grant from the BS. For example, the BS may provide the UE with resources for transmission of a PSCCH and/or a PSSCH by the dynamic grant. For example, a transmitting UE may report an SL hybrid automatic repeat request (SL HARQ) feedback received from a receiving UE to the BS. In this case, PUCCH resources and a timing for reporting the SL HARQ feedback to the BS may be determined based on an indication in a PDCCH, by which the BS allocates resources for SL transmission.

For example, the DCI may indicate a slot offset between the DCI reception and a first SL transmission scheduled by the DCI. For example, a minimum gap between the DCI that schedules the SL transmission resources and the resources of the first scheduled SL transmission may not be smaller than a processing time of the UE.

For example, in NR resource allocation mode <NUM>, the UE may be periodically provided with or allocated a resource set for a plurality of SL transmissions through a configured grant from the BS. For example, the grant to be configured may include configured grant type <NUM> or configured grant type <NUM>. For example, the UE may determine a TB to be transmitted in each occasion indicated by a given configured grant.

For example, the BS may allocate SL resources to the UE in the same carrier or different carriers.

For example, an NR gNB may control LTE-based SL communication. For example, the NR gNB may transmit NR DCI to the UE to schedule LTE SL resources. In this case, for example, a new RNTI may be defined to scramble the NR DCI. For example, the UE may include an NR SL module and an LTE SL module.

For example, after the UE including the NR SL module and the LTE SL module receives NR SL DCI from the gNB, the NR SL module may convert the NR SL DCI into LTE DCI type 5A, and transmit LTE DCI type 5A to the LTE SL module every Xms. For example, after the LTE SL module receives LTE DCI format 5A from the NR SL module, the LTE SL module may activate and/or release a first LTE subframe after Z ms. For example, X may be dynamically indicated by a field of the DCI. For example, a minimum value of X may be different according to a UE capability. For example, the UE may report a single value according to its UE capability. For example, X may be positive.

Referring to <FIG>, in LTE transmission mode <NUM>, LTE transmission mode <NUM>, or NR resource allocation mode <NUM>, the UE may determine SL transmission resources from among SL resources preconfigured or configured by the BS/network. For example, the preconfigured or configured SL resources may be a resource pool. For example, the UE may autonomously select or schedule SL transmission resources. For example, the UE may select resources in a configured resource pool on its own and perform SL communication in the selected resources. For example, the UE may select resources within a selection window on its own by a sensing and resource (re)selection procedure. For example, the sensing may be performed on a subchannel basis. UE1, which has autonomously selected resources in a resource pool, may transmit SCI to UE2 on a PSCCH and then transmit data based on the SCI to UE2 on a PSSCH.

For example, a UE may help another UE with SL resource selection. For example, in NR resource allocation mode <NUM>, the UE may be configured with a grant configured for SL transmission. For example, in NR resource allocation mode <NUM>, the UE may schedule SL transmission for another UE. For example, in NR resource allocation mode <NUM>, the UE may reserve SL resources for blind retransmission.

For example, in NR resource allocation mode <NUM>, UE1 may indicate the priority of SL transmission to UE2 by SCI. For example, UE2 may decode the SCI and perform sensing and/or resource (re)selection based on the priority. For example, the resource (re)selection procedure may include identifying candidate resources in a resource selection window by UE2 and selecting resources for (re)transmission from among the identified candidate resources by UE2. For example, the resource selection window may be a time interval during which the UE selects resources for SL transmission. For example, after UE2 triggers resource (re)selection, the resource selection window may start at T1 ≥ <NUM>, and may be limited by the remaining packet delay budget of UE2. For example, when specific resources are indicated by the SCI received from UE1 by the second UE and an L1 SL reference signal received power (RSRP) measurement of the specific resources exceeds an SL RSRP threshold in the step of identifying candidate resources in the resource selection window by UE2, UE2 may not determine the specific resources as candidate resources. For example, the SL RSRP threshold may be determined based on the priority of SL transmission indicated by the SCI received from UE1 by UE2 and the priority of SL transmission in the resources selected by UE2.

For example, the L1 SL RSRP may be measured based on an SL demodulation reference signal (DMRS). For example, one or more PSSCH DMRS patterns may be configured or preconfigured in the time domain for each resource pool. For example, PDSCH DMRS configuration type <NUM> and/or type <NUM> may be identical or similar to a PSSCH DMRS pattern in the frequency domain. For example, an accurate DMRS pattern may be indicated by the SCI. For example, in NR resource allocation mode <NUM>, the transmitting UE may select a specific DMRS pattern from among DMRS patterns configured or preconfigured for the resource pool.

For example, in NR resource allocation mode <NUM>, the transmitting UE may perform initial transmission of a TB without reservation based on the sensing and resource (re)selection procedure. For example, the transmitting UE may reserve SL resources for initial transmission of a second TB using SCI associated with a first TB based on the sensing and resource (re)selection procedure.

For example, in NR resource allocation mode <NUM>, the UE may reserve resources for feedback-based PSSCH retransmission through signaling related to a previous transmission of the same TB. For example, the maximum number of SL resources reserved for one transmission, including a current transmission, may be <NUM>, <NUM> or <NUM>. For example, the maximum number of SL resources may be the same regardless of whether HARQ feedback is enabled. For example, the maximum number of HARQ (re)transmissions for one TB may be limited by a configuration or preconfiguration. For example, the maximum number of HARQ (re)transmissions may be up to <NUM>. For example, if there is no configuration or preconfiguration, the maximum number of HARQ (re)transmissions may not be specified. For example, the configuration or preconfiguration may be for the transmitting UE. For example, in NR resource allocation mode <NUM>, HARQ feedback for releasing resources which are not used by the UE may be supported.

For example, in NR resource allocation mode <NUM>, the UE may indicate one or more subchannels and/or slots used by the UE to another UE by SCI. For example, the UE may indicate one or more subchannels and/or slots reserved for PSSCH (re)transmission by the UE to another UE by SCI. For example, a minimum allocation unit of SL resources may be a slot. For example, the size of a subchannel may be configured or preconfigured for the UE.

While control information transmitted from a BS to a UE on a PDCCH is referred to as DCI, control information transmitted from one UE to another UE on a PSCCH may be referred to as SCI. For example, the UE may know the starting symbol of the PSCCH and/or the number of symbols in the PSCCH before decoding the PSCCH. For example, the SCI may include SL scheduling information. For example, the UE may transmit at least one SCI to another UE to schedule the PSSCH. For example, one or more SCI formats may be defined.

For example, the transmitting UE may transmit the SCI to the receiving UE on the PSCCH. The receiving UE may decode one SCI to receive the PSSCH from the transmitting UE.

For example, the transmitting UE may transmit two consecutive SCIs (e.g., <NUM>-stage SCI) on the PSCCH and/or PSSCH to the receiving UE. The receiving UE may decode the two consecutive SCIs (e.g., <NUM>-stage SCI) to receive the PSSCH from the transmitting UE. For example, when SCI configuration fields are divided into two groups in consideration of a (relatively) large SCI payload size, SCI including a first SCI configuration field group is referred to as first SCI. SCI including a second SCI configuration field group may be referred to as second SCI. For example, the transmitting UE may transmit the first SCI to the receiving UE on the PSCCH. For example, the transmitting UE may transmit the second SCI to the receiving UE on the PSCCH and/or PSSCH. For example, the second SCI may be transmitted to the receiving UE on an (independent) PSCCH or on a PSSCH in which the second SCI is piggybacked to data. For example, the two consecutive SCIs may be applied to different transmissions (e.g., unicast, broadcast, or groupcast).

For example, the transmitting UE may transmit all or part of the following information to the receiving UE by SCI. For example, the transmitting UE may transmit all or part of the following information to the receiving UE by first SCI and/or second SCI.

For example, the first SCI may include information related to channel sensing. For example, the receiving UE may decode the second SCI using the PSSCH DMRS. A polar code used for the PDCCH may be applied to the second SCI. For example, the payload size of the first SCI may be equal for unicast, groupcast and broadcast in a resource pool. After decoding the first SCI, the receiving UE does not need to perform blind decoding on the second SCI. For example, the first SCI may include scheduling information about the second SCI.

In various embodiments of the present disclosure, since the transmitting UE may transmit at least one of the SCI, the first SCI, or the second SCI to the receiving UE on the PSCCH, the PSCCH may be replaced with at least one of the SCI, the first SCI, or the second SC. Additionally or alternatively, for example, the SCI may be replaced with at least one of the PSCCH, the first SCI, or the second SCI. Additionally or alternatively, for example, since the transmitting UE may transmit the second SCI to the receiving UE on the PSSCH, the PSSCH may be replaced with the second SCI.

In the case of mmWave, since an effect of phase noise is large due to damage to RF hardware, a transmitted or received signal is distorted in the time domain. Such phase noise causes common phase error (CPE) and inter-carrier interference (ICI) in the frequency domain. In particular, it may be possible to compensate for phase noise of an oscillator in a high carrier frequency, and the phase noise may cause the same phase rotation for all subcarriers. Thus, in order to estimate and compensate for such CPE, a PTRS is defined in NR.

In a DL PTRS-related operation, a BS may transmit PTRS configuration information to a UE. The PTRS configuration information may refer to PTRS-DownlinkConfig IE. The PTRS-DownlinkConfig IE may include a frequencyDensity parameter, a timeDensity parameter, an epre-Ratio parameter, and a resourceElementOffset parameter. The 'frequencyDensity' parameter may be a function of a scheduled BW and may be a parameter indicating presence and frequency density of a DL PTRS. The 'timeDensity' parameter may be a function of a modulation and coding scheme (MCS) and may be a parameter indicating presence and time density of a DL PTRS. The 'epre-Ratio' parameter may be a parameter indicating energy per resource element (EPRE) between a PTRS and a PDSCH.

The BS may generate a sequence used in a PTRS according to the PTRS configuration information. The sequence for the PTRS may be generated using a DMRS sequence of the same subcarrier. Generation of the sequence for the PTRS may be differently defined according to whether transform precoding is enabled.

The BS may map the generated sequence to resource elements. The PTRS may be mapped to a time domain resource at a specific symbol interval starting from a start symbol of PDSCH allocation, and when a DMRS symbol is present, the PTRS may be mapped from a symbol next to the DMRS symbol. The specific symbol interval may be <NUM>, <NUM>, or <NUM> symbols. In relation to mapping of a resource element of the PTRS, a frequency position of the PTRS may be determined according to a frequency position of a related DMRS port and UL-PTRS-RE-offset of an RRC parameter. Here, the UL-PTRS-RE-offset may be included in a PTRS configuration and may indicate subcarrier offset of a UL PTRS for CP-OFDM. In the case of DL, the PTRS port may be related to a DMRS port of the lowest index between scheduled DMsRS ports. In the case of UL, the BS may configure which DMRS port is related to a PTRS port through UL DCI.

The BS may transmit the PTRS to the UE on the resource elements. The UE may compensate for phase noise using the received PTRS.

A UL PTRS-related operation may be similar to the aforementioned UL PTRS-related operation, and terms of parameters related to DL may be substituted with terms of parameters related to UL.

That is, the PTRS-DownlinkConfig IE may be substituted with the PTRS-UplinkConfig IE, and in the DL PTRS-related operation, the BS may be substituted with the UE, and the UE may be substituted with the BS.

Similarly, generation of the sequence for the PTRS may be differently defined according to whether transform precoding is enabled.

Table <NUM> below shows generation of a sequence of PT-PS.

In an NR sidelink communication environment, the number and position of a PSSCH DMRS symbol in one slot may be configured as shown in Table <NUM> below according to a PSSCH symbol length, the PSCCH duration, and the number of symbols of a PSSCH DMRS in one slot (refer to 3GPP TS <NUM>).

In Table <NUM> above, ld refers to the number of symbols of a PSSCH (including a first symbol used for an AGC operation). In Table <NUM> above, each number refers to an SL symbol index at which a PSSCH DMRS symbol is positioned according to the PSCCH duration (<NUM> symbols or <NUM> symbols). In this case, the PSSCH DMRS in one slot may be frequency division multiplexed (FDM) with the PSCCH. For example, in the case of ld = <NUM>, the number of PSSCH DMRSs = <NUM>, and the PSCCH duration =<NUM>, the PSSCH DMRS may be positioned as shown in <FIG>. In the following example, a PSSCH DMRS of NR sidelink may be assumed to be a NR Uu Type <NUM> DMRS.

In an NR sidelink communication environment, a phase-tracking reference signal (PT-RS) may be introduced in order to overcome signal degradation due to UEs that operate at high speed [RAN1 AH-<NUM> chairman's note]. Currently, mapping of a physical resource to a PT-RS for a PSSCH is defined based on Rel-<NUM> NR Uu PUSCH PT-PS, but generation of the PT-RS signal is not defined. Thus, hereinafter, an embodiment of the present disclosure proposes a method of generating a PT-RS sequence (for a PSSCH) in NR sidelink (based on the Rel-<NUM> NR Uu PUSCH PT-RS) and an apparatus for supporting the method.

According to an embodiment, the UE may generate a DMRS related to a physical sidelink shared channel (PSSCH) (hereinafter, a PSSCH DMRS) (S1201 of <FIG>) and may generate a PTRS related to the PSSCH (S1202 of <FIG>). The UE may transmit at least a portion of the DMRS and the PTRS (S1203 of <FIG>).

Here, a DMRS sequence mapped to a predetermined position in a first PSSCH symbol in which the DMRS is transmitted may be used to generate the PTRS. The predetermined position (in the first PSSCH symbol) may correspond to a frequency position (subcarrier) in which the PTRS is transmitted.

Based on that a resource region of the PSSCH overlaps in part with a resource region of a physical sidelink control channel (PSCCH), the predetermined position may include a frequency position in which the generated DMRS is not transmitted. The frequency position in which the DMRS is not transmitted may overlap with a physical sidelink control channel (PSCCH).

That is, when a PSCCH (resource region) overlaps with a PSSCH (resource region)/PSSCH DMRS, a PSCCH may be transmitted and a PSSCH or a PSSCH DMRS may not overlap with each other in the overlapping region. That is, in a portion of the DMRS (RE) mapped to the PSSCH resource region, which overlaps with the PSCCH, the generated PSSCH DMRS sequence may be mapped to a resource region (RE) but may not be actually transmitted due to the PSCCH. However, as such, even if the PSCCH (resource region) and the PSSCH (resource region)/PSSCH DMRS overlap with each other and the PSSCH DMRS is not actually transmitted after being generated/mapped, the PSSCH DMRS may be used to generate the PTRS sequence corresponding to the corresponding frequency position. In the time axis corresponding to the first PSSCH symbol, the PSSCH and the PSCCH may be frequency division multiplexed (FDM).

In the above description, when the resource region of the PSSCH overlaps in part with the resource region of a physical sidelink control channel (PSCCH), this means that the aforementioned PSCCH (resource region) partially overlaps with the PSSCH (resource region)/PSSCH DMRS. Accordingly, the "first PSSCH symbol in which a DMRS is transmitted" may correspond to a symbol in which a part of the DMRS is transmitted first in a slot. For example, in Table <NUM> above, in each case in which a symbol #<NUM> is used as the DMSR position, the resource region of the PSSCH overlaps in part with the resource region of the PSCCH, and the "first PSSCH symbol in which a DMRS is transmitted" may correspond to the symbol #<NUM>. In detail, for example, when the PSSCH is transmitted in <NUM> symbols and a DMRS is mapped to symbols #<NUM> and #<NUM>, the DMRS may be partially transmitted due to partial overlapping in the symbol #<NUM>, and thus the symbol #<NUM> may correspond to the "first PSSCH symbol in which a DMRS is transmitted".

When the PSCCH (resource region) and the PSSCH (resource region)/PSSCH DMRS entirely overlap with each other, the "first PSSCH symbol in which a DMRS is transmitted" may correspond to a symbol in which the DMRS is transmitted first after overlapping. In other words, based on that the resource region of the PSCCH entirely overlaps with the resource region of the PSSCH, the first PSSCH symbol in which a DMRS is transmitted may be a symbol in which the DMRS is transmitted first after the resource region of the PSCCH. For example, in Table <NUM> above, in each case in which a symbol #<NUM> is used as the DMSR position, the resource region of the PSSCH entirely overlaps with the resource region of the PSCCH, and the "first PSSCH symbol in which a DMRS is transmitted" may correspond to symbols #<NUM> to #<NUM> but not the symbol #<NUM>. In detail, for example, when the PSSCH is transmitted in <NUM> symbols and a DMRS is mapped to symbols #<NUM> and #<NUM>, the symbol #<NUM> may not be transmitted due to entire overlapping in the symbol #<NUM>, and thus the symbol #<NUM> may correspond to the "first PSSCH symbol in which a DMRS is transmitted".

The PTRS may not be transmitted when overlapping with the PSCCH. That is, when an RE to which the PTRS generated using the DMRS sequence is mapped overlaps with the PSCCH, the PTRS may not be transmitted due to puncturing.

<FIG> illustrates an example related to the above description. In <FIG>, an RE mapped to each signal is exemplary, and a relevant part of TS <NUM> will be referred to for more accurate signal mapping RE location.

Referring to <FIG>, a sequence of first DMRS symbols <NUM> and <NUM> positioned in the corresponding frequency domain may be used. In <FIG>, a first PSSCH symbol in which a DMRS is transmitted may correspond to a symbol #<NUM>. As described above, the DMRS sequence mapped to a predetermined position may be used to generate the PTRS, and the predetermined position in <FIG> may be, for example, REs <NUM> and <NUM> of the symbol #<NUM>, which correspond to subcarriers #<NUM> and #<NUM> in a symbol #<NUM> in which the PTRS is transmitted. The REs <NUM> and <NUM> as the predetermined position may include the RE <NUM> in which the generated DMRS is not transmitted. That is, when a PSCCH and a PSSCH overlap with each other, even if a DMRS sequence mapped to the RE <NUM> is not transmitted due to overlapping with the PSCCH, the DMRS sequence may be used to generate a PTRS sequence corresponding to the corresponding frequency position.

As configured above, when the sequence of the PTRS is generated based on the DMRS sequence or using the DMRS sequence, if the PSCCH and the PSSCH partially/entirely overlap with each other and a DMRS is not transmitted due to a channel structure of sidelink, it may be possible to overcome ambiguity of which reference needs to be used to generate the PTRS sequence corresponding to the frequency position. In terms of implementation of a UE, in the case of a portion of a DMRS sequence that is not used in actual DMRS transmission, it may be advantageously clear whether the UE needs to (still) generate/store the value and use the value to generate the PT-RS sequence.

Hereinafter, various PTRS generation methods exemplified in <FIG> will be described.

When a PTRS is configured as shown in <FIG>, a sequence of a first DMRS symbol <NUM> positioned in the corresponding frequency domain may be used to generate the PTRS sequence (as described above).

When the PTRS is configured as shown in <FIG> below, that is, when the PTRS overlaps with (at least a portion) of the PSCCH, generation of the PTRS sequence may be considered using the following method.

First, as shown in <FIG>, like in the aforementioned existing PTRS sequence generation method, a sequence of a first DMRS symbol <NUM> positioned in the corresponding frequency domain may be used.

Alternatively, as shown in <FIG>, a sequence of a first DMRS symbol <NUM> with which the PSCCH is not frequency division multiplexed (FDM) (or overlaps) may be used to generate the PTRS sequence.

Alternatively, as shown in <FIG>, a sequence of a DMRS symbol <NUM> positioned in the corresponding frequency domain, which is present after a position with which the PSCCH is not frequency division multiplexed (FDM) (or overlaps) may be used to generate the PTRS sequence.

Alternatively, as shown in <FIG>, a sequence of a last DMRS symbol <NUM> positioned in the corresponding frequency domain may be used to generate the PTRS sequence.

When the PTRS is configured as shown in <FIG> below, that is, a partial PTRS may not overlap with the PSCCH and a partial PTRS overlaps with (at least a portion) of the PSCCH, generation of the PTRS sequence may be considered using the following method.

First, as shown in <FIG>, like in the aforementioned existing PTRS sequence generation method, a sequence of first DMRS symbols <NUM> and <NUM> positioned in the corresponding frequency domain may be used.

Alternatively, as shown in <FIG>, in the case of a PTRS that does not overlap with the PSCCH, an existing PTRS sequence generation method may be used. That is, a sequence of a first DMRS symbol <NUM> positioned in the corresponding frequency domain may be used. In the case of a PTRS that overlaps with the PSCCH, a sequence of a first DMRS symbol <NUM> with which the PSCCH is not frequency division multiplexed (FDM) (or overlaps) may be used, like in the description of <FIG>.

Alternatively, as shown in <FIG>, in the case of a PTRS that does not overlap with the PSCCH, an existing PTRS sequence generation method may be used. That is, a sequence of a first DMRS symbol <NUM> positioned in the corresponding frequency domain may be used. In the case of a PTRS that overlaps with the PSCCH, a sequence of a DMRS symbol <NUM> positioned in the corresponding frequency domain, which is present after a position with which the PSCCH is not frequency division multiplexed (FDM) (or overlaps) may be used to generate the PTRS sequence, like in the description of <FIG>.

Alternatively, as shown in <FIG>, in the case of a PTRS that does not overlap with the PSCCH, an existing PTRS sequence generation method may be used. That is, a sequence of a first DMRS symbol <NUM> positioned in the corresponding frequency domain may be used. In the case of a PTRS that overlaps with the PSCCH, a sequence of a last DMRS symbol <NUM> positioned in the corresponding frequency domain may be used to generate a PTRS sequence, like in the description of <FIG>.

Alternatively, as shown in <FIG>, in the case of all PTRSs that do not overlap with the PSCCH or overlap with the PSCCH, a sequence of DMRS symbols <NUM> and <NUM> positioned in the corresponding frequency domain, which is present after a position with which the PSCCH is not frequency division multiplexed (FDM) (or overlaps) may be used to generate the PTRS sequence, like in the description of <FIG>.

Alternatively, as shown in <FIG>, in the case of all PTRSs that do not overlap with the PSCCH or overlap with the PSCCH, a sequence of last DMRS symbols <NUM> and <NUM> positioned in the corresponding frequency domain may be used to generate the PTRS sequence, like in the description of <FIG>.

The position of the PSSCH DMRS used to generate the PTRS sequence may be previously configured by a network/BS (resource pool-specifically) or may be configured via signaling (e.g., PC-<NUM> RRC signaling) predefined between UEs.

As described above, when the PT-RS sequence uses a DMRS sequence in the same way, in the following equation
<MAT>.

For example, the case of j = j' may be based on a method in which a PT-RS is mapped only in a corresponding antenna port and uses an r(m) sequence, and a null (<NUM>) value is used in the other antenna port, and in NR sidelink, only two antenna ports are supported in the PT-RS and the DMRS, and thus PT-RS sequence generation may be considered using the following method.

For example, a PT-RS may be mapped to two antenna ports, and the same sequence may be used for each antenna port.

In another example, a PT-RS may be mapped to two antenna ports, and different sequences may be used for the respective antenna ports. <MAT> <MAT>.

In another example, a PT-RS may be mapped only to one antenna port, and the same sequence may be used for each antenna port. <MAT> <MAT>.

In another example, a PT-RS may be mapped only to one antenna port, and different sequences may be used for the respective antenna ports. <MAT> <MAT>.

(Other than the above description) only some of sequences used to generate a DMRS when a PT-RS sequence is used in a PT-RS. For example, some values may be used in the order of the smallest (or greatest) of values m used in a DMRS when the PT-RS sequence is generated. Alternatively, the PT-RS sequence may be generated based on a value m preconfigured (for each antenna port).

In Table <NUM> above, ld refers to the number of symbols of a PSSCH (including a first symbol used for an AGC operation) in NR V2X. In Table <NUM> above, each number refers to an SL symbol index at which a PSSCH DMRS symbol is positioned according to PSCCH duration (<NUM> symbols or <NUM> symbols). For example, <FIG> illustrates the case in which ld is <NUM> and PSCCH duration is <NUM> symbols (PSSCH DMRS symbol index: <NUM> and <NUM>), and <FIG> illustrates the case in which ld is13, PSCCH duration is <NUM> symbols, and the number of PSSCH DMRSs is <NUM> (PSSCH DMRS symbol index: <NUM>, <NUM>, <NUM>, and <NUM>). [R1-<NUM>].

PRBs {<NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, and <NUM>} may be supported as a sub-channel size of an available resource pool in Rel-<NUM> NR V2X, and PRBs {<NUM>, <NUM>, <NUM>, <NUM>, and <NUM>} may be supported as the number of RBs of an available PSCCH. In this case, a PSSCH DMRS (irrespective of the number of PSSCH DMRSs (e.g., <NUM>, <NUM>, or <NUM>) may not be present in one sub-channel in which the PSCCH is present when the sub-channel size of the resource pool and the number of RBs of the PSCCH are the same. For example, <FIG> illustrates the case in which the sub-channel size of the resource pool and the number of RBs of the PSCCH are the same (ld =<NUM>, PSCCH duration = <NUM> symbols, and the number of PSSCH DMRSs = <NUM>).

As seen from the above example, the number of indicated PSSCH DMRSs may be <NUM>, but the number of actually used PSSCH DMRSs may be <NUM>. Thus, the following methods may be used to handle this mismatch.

[Method <NUM>] When the sub-channel size of the resource pool and the number of RBs of the PSCCH are the same, only the remaining number obtained by subtracting the number (e.g., <NUM>) of PSSCH DMRSs truncated by the PSCCH from the number of indicated PSSCH DMRSs may be assumed to be the number of actually used PSSCH DMRSs in actual PSSCH DMRS transmission.

[Method <NUM>] The UE may expect/consider/assume/premise only that the sub-channel size of the resource pool is configured to be greater than the number of RBs of the PSCCH from the BS/network. In this case, a PSSCH DMRS needs to be present in one sub-channel in which a PSCCH is present.

[Method <NUM>] When the sub-channel size of the resource pool and the number of RBs of the PSCCH are the same, the sub-channel size of the PSSCH may be configured to allow two or more. In this case, in a plurality of sub-channels in which the PSSCH is transmitted (even if a portion of a sub-channel on the frequency axis is truncated by the PSCCH), the number of PSSCH DMRSs may be still maintained/ensured.

[Method <NUM>] A network may (pre)configure one of [Method <NUM>], [Method <NUM>], or [Method <NUM>].

In the above description, which option is applied for the number of PSSCH DMRSs may be differently configured for each service QOS requirement (e.g., RELIABILITY) (and/or a service priority/type) (e.g., in the case of a service of relatively low RELIABILITY requirement, [Method <NUM>] application may be configured).

In NR V2X, in the case of SCS of <NUM>, an extended cyclic prefix (ECP) may be supported. In the case of ECP, the number of symbols of a slot is <NUM>, and thus when the ECP is supported, Table <NUM> indicating PSSCH DMRSs may not be applied in the same way.

Thus, hereinafter, an embodiment of the present disclosure proposes a method of notifying density and location information on the time axis of a PSSCH DMRS and an apparatus for supporting the method when the ECP is supported.

First, when the ECP is supported, the case in which ld is equal to or greater than <NUM> is physically impossible, and thus the number and location of PSSCH DMRSs in one slot may be defined as shown in Table <NUM> below.

Half of a slot includes <NUM> symbols, it is necessary to support the case in which a ld value is <NUM> for an operation in the half slot. Thus, as shown in Table <NUM> below, the number and position of PSSCH DMRSs in one slot may be defined.

In the case of SCS of <NUM>, PSSCH performance is guaranteed even when a DMRS is equal to or less than <NUM> symbols in one slot [R1-<NUM>], and thus in the case of ECP, the number and position of PSSCH DMRSs may be defined in one slot as shown in Tables <NUM> to <NUM> below. That is, in the case of the ECP, up to <NUM> symbols of the PSSCH DMRS may be used in one slot.

In the above example, in the case of the ECP, the PSCCH duration may be restricted to <NUM> symbols. In this case, as shown in Tables <NUM> to <NUM>, the number and position of PSSCH DMRSs in one slot may be defined.

In this case, for example, (the aforementioned) PT-RS sequence generation-related information (and/or information on whether to apply a proposed rule) may be differently (or independently) configured (by a network/BS) specifically for a resource pool (and/or a service type/priority, a (service) QOS parameter (e.g., reliability and latency), an (absolute or relative) speed of a UE, a UE type, a subchannel size, and/or a size of scheduled frequency resource region), or may be implicitly determined based on a preconfigured parameter (e.g., a frequency resource size).

Referring to <FIG>, a communication system <NUM> applied to the present disclosure includes wireless devices, BSs, and a network. Herein, the wireless devices represent devices performing communication using RAT (e.g., <NUM> NR or LTE) and may be referred to as communication/radio/SG devices. The wireless devices may include, without being limited to, a robot 100a, vehicles 100b-<NUM> and 100b-<NUM>, an extended reality (XR) device 100c, a hand-held device 100d, a home appliance 100e, an Internet of things (IoT) device 100f, and an artificial intelligence (AI) device/server <NUM>. Herein, the vehicles may include an unmanned aerial vehicle (UAV) (e.g., a drone). The XR device may include an augmented reality (AR)/virtual reality (VR)/mixed reality (MR) device and may be implemented in the form of a head-mounted device (HMD), a head-up display (HUD) mounted in a vehicle, a television, a smartphone, a computer, a wearable device, a home appliance device, a digital signage, a vehicle, a robot, etc. The hand-held device may include a smartphone, a smartpad, a wearable device (e.g., a smartwatch or a smartglasses), and a computer (e.g., a notebook). For example, the BSs and the network may be implemented as wireless devices and a specific wireless device 200a may operate as a BS/network node with respect to other wireless devices.

For example, the vehicles 100b-<NUM> and 100b-<NUM> may perform direct communication (e.g. V2V/V2X communication).

Wireless communication/connections 150a, 150b, or 150c may be established between the wireless devices 100a to 100f/BS <NUM>, or BS <NUM>/BS <NUM>. Herein, the wireless communication/connections may be established through various RATs (e.g., <NUM> NR) such as UL/DL communication 150a, sidelink communication 150b (or, D2D communication), or inter BS communication (e.g. relay, integrated access backhaul (IAB)). The wireless devices and the BSs/the wireless devices may transmit/receive radio signals to/from each other through the wireless communication/connections 150a and 150b. For example, the wireless communication/connections 150a and 150b may transmit/receive signals through various physical channels. To this end, at least a part of various configuration information configuring processes, various signal processing processes (e.g., channel encoding/decoding, modulation/demodulation, and resource mapping/demapping), and resource allocating processes, for transmitting/receiving radio signals, may be performed based on the various proposals of the present disclosure.

The one or more processors <NUM> and <NUM> may generate one or more Protocol Data Units (PDUs) and/or one or more service data unit (SDUs) according to the descriptions, functions, procedures, proposals, methods, and/or operational flowcharts disclosed in this document.

As an example, one or more application specific integrated circuits (ASICs), one or more digital signal processors (DSPs), one or more digital signal processing devices (DSPDs), one or more programmable logic devices (PLDs), or one or more field programmable gate arrays (FPGAs) may be included in the one or more processors <NUM> and <NUM>.

<FIG> illustrates a vehicle or an autonomous driving vehicle applied to the present disclosure. The vehicle or autonomous driving vehicle may be implemented by a mobile robot, a car, a train, a manned/unmanned aerial vehicle (AV), a ship, etc..

Referring to <FIG>, a vehicle or autonomous driving vehicle <NUM> may include an antenna unit <NUM>, a communication unit <NUM>, a control unit <NUM>, a driving unit 140a, a power supply unit 140b, a sensor unit 140c, and an autonomous driving unit 140d. The blocks <NUM>/<NUM>/140a to 140d correspond to the blocks <NUM>/<NUM>/<NUM> of FIG. <NUM>, respectively.

The control unit <NUM> may perform various operations by controlling elements of the vehicle or the autonomous driving vehicle <NUM>. The control unit <NUM> may include an ECU. The driving unit 140a may cause the vehicle or the autonomous driving vehicle <NUM> to drive on a road. The driving unit 140a may include an engine, a motor, a powertrain, a wheel, a brake, a steering device, etc. The power supply unit 140b may supply power to the vehicle or the autonomous driving vehicle <NUM> and include a wired/wireless charging circuit, a battery, etc. The sensor unit 140c may acquire a vehicle state, ambient environment information, user information, etc. The sensor unit 140c may include an inertial measurement unit (IMU) sensor, a collision sensor, a wheel sensor, a speed sensor, a slope sensor, a weight sensor, a heading sensor, a position module, a vehicle forward/backward sensor, a battery sensor, a fuel sensor, a tire sensor, a steering sensor, a temperature sensor, a humidity sensor, an ultrasonic sensor, an illumination sensor, a pedal position sensor, etc. The autonomous driving unit 140d may implement technology for maintaining a lane on which a vehicle is driving, technology for automatically adjusting speed, such as adaptive cruise control, technology for autonomously driving along a determined path, technology for driving by automatically setting a path if a destination is set, and the like.

For example, the communication unit <NUM> may receive map data, traffic information data, etc. from an external server. The autonomous driving unit 140d may generate an autonomous driving path and a driving plan from the obtained data. The control unit <NUM> may control the driving unit 140a such that the vehicle or the autonomous driving vehicle <NUM> may move along the autonomous driving path according to the driving plan (e.g., speed/direction control). In the middle of autonomous driving, the communication unit <NUM> may aperiodically/periodically acquire recent traffic information data from the external server and acquire surrounding traffic information data from neighboring vehicles. In the middle of autonomous driving, the sensor unit 140c may obtain a vehicle state and/or surrounding environment information. The autonomous driving unit 140d may update the autonomous driving path and the driving plan based on the newly obtained data/information. The communication unit <NUM> may transfer information about a vehicle position, the autonomous driving path, and/or the driving plan to the external server. The external server may predict traffic information data using AI technology, etc., based on the information collected from vehicles or autonomous driving vehicles and provide the predicted traffic information data to the vehicles or the autonomous driving vehicles.

<FIG> illustrates a vehicle applied to the present disclosure. The vehicle may be implemented as a transport means, an aerial vehicle, a ship, etc..

Referring to <FIG>, a vehicle <NUM> may include a communication unit <NUM>, a control unit <NUM>, a memory unit <NUM>, an I/O unit 140a, and a positioning unit 140b. Herein, the blocks <NUM> to <NUM>/140a and 140b correspond to blocks <NUM> to <NUM>/<NUM> of FIG.

The communication unit <NUM> may transmit and receive signals (e.g., data and control signals) to and from external devices such as other vehicles or BSs. The control unit <NUM> may perform various operations by controlling constituent elements of the vehicle <NUM>. The memory unit <NUM> may store data/parameters/programs/code/commands for supporting various functions of the vehicle <NUM>. The I/O unit 140a may output an AR/VR object based on information within the memory unit <NUM>. The I/O unit 140a may include an HUD. The positioning unit 140b may acquire information about the position of the vehicle <NUM>. The position information may include information about an absolute position of the vehicle <NUM>, information about the position of the vehicle <NUM> within a traveling lane, acceleration information, and information about the position of the vehicle <NUM> from a neighboring vehicle. The positioning unit 140b may include a GPS and various sensors.

As an example, the communication unit <NUM> of the vehicle <NUM> may receive map information and traffic information from an external server and store the received information in the memory unit <NUM>. The positioning unit 140b may obtain the vehicle position information through the GPS and various sensors and store the obtained information in the memory unit <NUM>. The control unit <NUM> may generate a virtual object based on the map information, traffic information, and vehicle position information and the I/O unit 140a may display the generated virtual object in a window in the vehicle (<NUM> and <NUM>). The control unit <NUM> may determine whether the vehicle <NUM> normally drives within a traveling lane, based on the vehicle position information. If the vehicle <NUM> abnormally exits from the traveling lane, the control unit <NUM> may display a warning on the window in the vehicle through the I/O unit 140a. In addition, the control unit <NUM> may broadcast a warning message regarding driving abnormity to neighboring vehicles through the communication unit <NUM>. According to situation, the control unit <NUM> may transmit the vehicle position information and the information about driving/vehicle abnormality to related organizations.

<FIG> illustrates an XR device applied to the present disclosure. The XR device may be implemented by an HMD, an HUD mounted in a vehicle, a television, a smartphone, a computer, a wearable device, a home appliance, a digital signage, a vehicle, a robot, etc..

Referring to <FIG>, an XR device 100a may include a communication unit <NUM>, a control unit <NUM>, a memory unit <NUM>, an I/O unit 140a, a sensor unit 140b, and a power supply unit 140c. Herein, the blocks <NUM> to <NUM>/140a to 140c correspond to the blocks <NUM> to <NUM>/<NUM> of FIG. <NUM>, respectively.

The communication unit <NUM> may transmit and receive signals (e.g., media data and control signals) to and from external devices such as other wireless devices, hand-held devices, or media servers. The media data may include video, images, and sound. The control unit <NUM> may perform various operations by controlling constituent elements of the XR device 100a. For example, the control unit <NUM> may be configured to control and/or perform procedures such as video/image acquisition, (video/image) encoding, and metadata generation and processing. The memory unit <NUM> may store data/parameters/programs/code/commands needed to drive the XR device 100a/generate XR object. The I/O unit 140a may obtain control information and data from the exterior and output the generated XR object. The I/O unit 140a may include a camera, a microphone, a user input unit, a display unit, a speaker, and/or a haptic module. The sensor unit 140b may obtain an XR device state, surrounding environment information, user information, etc. The sensor unit 140b may include a proximity sensor, an illumination sensor, an acceleration sensor, a magnetic sensor, a gyro sensor, an inertial sensor, an RGB sensor, an IR sensor, a fingerprint recognition sensor, an ultrasonic sensor, a light sensor, a microphone and/or a radar. The power supply unit 140c may supply power to the XR device 100a and include a wired/wireless charging circuit, a battery, etc..

For example, the memory unit <NUM> of the XR device 100a may include information (e.g., data) needed to generate the XR object (e.g., an AR/VR/MR object). The I/O unit 140a may receive a command for manipulating the XR device 100a from a user and the control unit <NUM> may drive the XR device 100a according to a driving command of a user. For example, when a user desires to watch a film or news through the XR device 100a, the control unit <NUM> transmits content request information to another device (e.g., a hand-held device 100b) or a media server through the communication unit <NUM>. The communication unit <NUM> may download/stream content such as films or news from another device (e.g., the hand-held device 100b) or the media server to the memory unit <NUM>. The control unit <NUM> may control and/or perform procedures such as video/image acquisition, (video/image) encoding, and metadata generation/processing with respect to the content and generate/output the XR object based on information about a surrounding space or a real object obtained through the I/O unit 140a/sensor unit 140b.

The XR device 100a may be wirelessly connected to the hand-held device 100b through the communication unit <NUM> and the operation of the XR device 100a may be controlled by the hand-held device 100b. For example, the hand-held device 100b may operate as a controller of the XR device 100a. To this end, the XR device 100a may obtain information about a 3D position of the hand-held device 100b and generate and output an XR object corresponding to the hand-held device 100b.

<FIG> illustrates a robot applied to the present disclosure. The robot may be categorized into an industrial robot, a medical robot, a household robot, a military robot, etc., according to a used purpose or field.

Referring to <FIG>, a robot <NUM> may include a communication unit <NUM>, a control unit <NUM>, a memory unit <NUM>, an I/O unit 140a, a sensor unit 140b, and a driving unit 140c. Herein, the blocks <NUM> to <NUM>/140a to 140c correspond to the blocks <NUM> to <NUM>/<NUM> of <FIG>, respectively.

The communication unit <NUM> may transmit and receive signals (e.g., driving information and control signals) to and from external devices such as other wireless devices, other robots, or control servers. The control unit <NUM> may perform various operations by controlling constituent elements of the robot <NUM>. The memory unit <NUM> may store data/parameters/programs/code/commands for supporting various functions of the robot <NUM>. The I/O unit 140a may obtain information from the exterior of the robot <NUM> and output information to the exterior of the robot <NUM>. The I/O unit 140a may include a camera, a microphone, a user input unit, a display unit, a speaker, and/or a haptic module. The sensor unit 140b may obtain internal information of the robot <NUM>, surrounding environment information, user information, etc. The sensor unit 140b may include a proximity sensor, an illumination sensor, an acceleration sensor, a magnetic sensor, a gyro sensor, an inertial sensor, an IR sensor, a fingerprint recognition sensor, an ultrasonic sensor, a light sensor, a microphone, a radar, etc. The driving unit 140c may perform various physical operations such as movement of robot joints. In addition, the driving unit 140c may cause the robot <NUM> to travel on the road or to fly. The driving unit 140c may include an actuator, a motor, a wheel, a brake, a propeller, etc..

<FIG> illustrates an AI device applied to the present disclosure. The AI device may be implemented by a fixed device or a mobile device, such as a TV, a projector, a smartphone, a PC, a notebook, a digital broadcast terminal, a tablet PC, a wearable device, a Set Top Box (STB), a radio, a washing machine, a refrigerator, a digital signage, a robot, a vehicle, etc..

Referring to <FIG>, an AI device <NUM> may include a communication unit <NUM>, a control unit <NUM>, a memory unit <NUM>, an I/O unit 140a/140b, a learning processor unit 140c, and a sensor unit 140d. The blocks <NUM> to <NUM>/140a to 140d correspond to blocks <NUM> to <NUM>/<NUM> of <FIG>, respectively.

The communication unit <NUM> may transmit and receive wired/radio signals (e.g., sensor information, user input, learning models, or control signals) to and from external devices such as other AI devices (e.g., 100x, <NUM>, or <NUM> of <FIG>) or an AI server (e.g., <NUM> of <FIG>) using wired/wireless communication technology. To this end, the communication unit <NUM> may transmit information within the memory unit <NUM> to an external device and transmit a signal received from the external device to the memory unit <NUM>.

The control unit <NUM> may determine at least one feasible operation of the AI device <NUM>, based on information which is determined or generated using a data analysis algorithm or a machine learning algorithm. The control unit <NUM> may perform an operation determined by controlling constituent elements of the AI device <NUM>. For example, the control unit <NUM> may request, search, receive, or use data of the learning processor unit 140c or the memory unit <NUM> and control the constituent elements of the AI device <NUM> to perform a predicted operation or an operation determined to be preferred among at least one feasible operation. The control unit <NUM> may collect history information including the operation contents of the AI device <NUM> and operation feedback by a user and store the collected information in the memory unit <NUM> or the learning processor unit 140c or transmit the collected information to an external device such as an AI server (<NUM> of <FIG>). The collected history information may be used to update a learning model.

The memory unit <NUM> may store data for supporting various functions of the AI device <NUM>. For example, the memory unit <NUM> may store data obtained from the input unit 140a, data obtained from the communication unit <NUM>, output data of the learning processor unit 140c, and data obtained from the sensor unit <NUM>. The memory unit <NUM> may store control information and/or software code needed to operate/drive the control unit <NUM>.

The input unit 140a may acquire various types of data from the exterior of the AI device <NUM>. For example, the input unit 140a may acquire learning data for model learning, and input data to which the learning model is to be applied. The input unit 140a may include a camera, a microphone, and/or a user input unit. The output unit 140b may generate output related to a visual, auditory, or tactile sense. The output unit 140b may include a display unit, a speaker, and/or a haptic module. The sensing unit <NUM> may obtain at least one of internal information of the AI device <NUM>, surrounding environment information of the AI device <NUM>, and user information, using various sensors. The sensor unit <NUM> may include a proximity sensor, an illumination sensor, an acceleration sensor, a magnetic sensor, a gyro sensor, an inertial sensor, an RGB sensor, an IR sensor, a fingerprint recognition sensor, an ultrasonic sensor, a light sensor, a microphone, and/or a radar.

The learning processor unit 140c may learn a model consisting of artificial neural networks, using learning data. The learning processor unit 140c may perform AI processing together with the learning processor unit of the AI server (<NUM> of <FIG>). The learning processor unit 140c may process information received from an external device through the communication unit <NUM> and/or information stored in the memory unit <NUM>. In addition, an output value of the learning processor unit 140c may be transmitted to the external device through the communication unit <NUM> and may be stored in the memory unit <NUM>.

Claim 1:
A method of transmitting a phase-tracking reference signal, PTRS, related to sidelink by a user equipment, UE, in a wireless communication system, the method comprising:
generating (S1201) a demodulation reference signals, DMRS, related to a physical sidelink shared channel, PSSCH;
generating (S1202) the PTRS related to the PSSCH; and
transmitting (S1203) at least a portion of the DMRS and the PTRS,
wherein:
a resource region of a physical sidelink control channel, PSCCH, overlaps with at least a part of a resource region of the PSSCH,
a DMRS sequence mapped to a predetermined position in a first PSSCH symbol in which the DMRS is transmitted is used to generate the PTRS;
the predetermined position corresponds to a frequency position at which the PTRS is transmitted; and
the predetermined position includes a frequency position at which transmission of the generated DMRS is skipped.