Method and apparatus for indicating sidelink radio link failure in a wireless communication system

Abstract

A method and apparatus for indicating a sidelink (SL) radio link failure (RLF) in a wireless communication system are provided. A first wireless device may initialize a counter to zero when 1) establishing a PC5-RRC connection with a second wireless device or 2) configuring or reconfiguring a maximum counter value. The first wireless device may increment the counter based on the failure to receive any acknowledgment for the transmission of a MAC PDU. The first wireless device may indicate a sidelink (SL) radio link failure (RLF) for the PC5-RRC connection based on the counter reaching the maximum counter value.

Description

Technical Field

[0001] The present disclosure relates to methods and apparatus for indicating sidelink (SL) radio link failure (RLF) in a wireless communication system. Background Art

[0002] The 3rd Generation Partnership Project (3GPP) Long Term Evolution (LTE) is a technology that enables high-speed packet communications. Many solutions have been proposed for LTE, including those aimed at reducing user and provider costs, improving service quality, and expanding and improving coverage and system capacity. As high-level requirements, 3GPP LTE requires reduced cost per bit, increased service availability, flexible use of frequency bands, a simple structure, open interfaces, and appropriate power consumption of terminals.

[0003] The International Telecommunication Union (ITU) and 3GPP have begun developing requirements and specifications for New Radio (NR) systems. 3GPP must identify and develop the technical components necessary for the successful standardization of new RATs that will meet both immediate market needs and the longer-term requirements outlined by the ITU Radiocommunication Sector (ITU-R) International Mobile Telecommunications (IMT)-2020 process. Furthermore, NR should be able to use any spectrum band available for wireless communications in the more distant future, at least up to 100 GHz.

[0004] The goal of NR is to be a single technology framework that addresses all use cases, requirements, and deployment scenarios, including enhanced mobile broadband (eMBB), massive machine-type communications (mMTC), ultra-reliable and low-latency communications (URLLC), etc. NR should be inherently forward-compatible.

[0005] Vehicle-to-everything (V2X) communication is the transfer of information from a vehicle to any entity that can affect the vehicle, and vice versa. It is a vehicle communication system that incorporates other more specific types of communication such as vehicle-to-infrastructure (V2I), vehicle-to-network (V2N), vehicle-to-vehicle (V2V), vehicle-to-pedestrian (V2P), vehicle-to-device (V2D), and vehicle-to-grid (V2G). Summary of the Invention

[0006] Technical Purpose

[0007] The wireless device may establish a unicast link and an associated PC5-RRC connection with another wireless device in a sidelink.

[0008] In this case, the wireless device may monitor the quality of the PC5-RRC connection based on hybrid automatic repeat request (HARQ) retransmissions. In this case, it is unclear how the wireless device declares a link failure on the PC5-RRC connection.

[0009] Therefore, there is a need for research for indicating a link (SL) radio link failure (RLF) in a wireless communication system.

[0010] Technical Solution

[0011] In one aspect, a method performed by a first wireless device in a wireless communication system is provided. The first wireless device may initialize a counter to zero when 1) establishing a PC5-RRC connection with a second wireless device or 2) configuring or reconfiguring a maximum number of the counter. The first wireless device may increment the counter based on the lack of receiving any acknowledgment for transmission of a MAC PDU. The first wireless device may indicate a sidelink (SL) radio link failure (RLF) for the PC5-RRC connection based on the counter reaching the maximum number of the counter.

[0012] In another aspect, a device for implementing the above method is provided.

[0013] Technical Effects

[0014] The present disclosure may have various advantageous effects.

[0015] According to some embodiments of the present disclosure, a wireless device may efficiently indicate a sidelink (SL) radio link failure (RLF) in a wireless communication system.

[0016] For example, a wireless device that performs radio link management by using HARQ feedback can appropriately detect radio link failure by considering HARQ feedback transmission from another wireless device.

[0017] For example, when a UE establishes a sidelink connection with a peer UE, the UE can appropriately detect radio link failure by considering HARQ feedback transmission from the other UE.

[0018] For example, the wireless communication system may appropriately provide radio link management for a sidelink connection for a UE performing HARQ transmission.

[0019] The advantageous effects that can be obtained by the specific embodiments of the present disclosure are not limited to the advantageous effects listed above. For example, there may be various technical effects that a person of ordinary skill in the relevant art can understand and / or deduce based on the present disclosure. Therefore, the specific effects of the present disclosure are not limited to those explicitly described herein, but can include various effects that can be understood or derived from the technical features of the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 An example of a communication system to which an implementation of the present disclosure is applied is shown.

[0021] Figure 2An example of a wireless device to which an implementation of the present disclosure is applied is shown.

[0022] Figure 3 An example of a wireless device to which an implementation of the present disclosure is applied is shown.

[0023] Figure 4 Another example of a wireless device to which implementations of the present disclosure are applied is shown.

[0024] Figure 5 An example of a UE to which an implementation of the present disclosure is applied is shown.

[0025] Figure 6 and Figure 7 An example of a protocol stack in a 3GPP-based wireless communication system to which implementations of the present disclosure are applied is shown.

[0026] Figure 8 The frame structure in a 3GPP-based wireless communication system to which the implementation of the present disclosure is applied is shown.

[0027] Figure 9 An example of data flow in a 3GPP NR system to which an implementation of the present disclosure is applied is shown.

[0028] Figure 10 and Figure 11 An example of a PC5 protocol stack to which an implementation of the present disclosure is applied is shown.

[0029] Figure 12 An example of a method for indicating a sidelink radio link failure in a wireless communication system according to some embodiments of the present disclosure is shown.

[0030] Figure 13 An example of a method for performing data transmission by a UE in a wireless communication system according to some embodiments of the present disclosure is shown.

[0031] Figure 14 An example of a method for sidelink HARQ transmission and failure detection from a UE in a wireless communication system according to some embodiments of the present disclosure is shown. DETAILED DESCRIPTION

[0032] The following techniques, devices, and systems can be applied to various wireless multiple access systems. Examples of multiple access systems include code division multiple access (CDMA) systems, frequency division multiple access (FDMA) systems, time division multiple access (TDMA) systems, orthogonal frequency division multiple access (OFDMA) systems, single carrier frequency division multiple access (SC-FDMA) systems, and multi-carrier frequency division multiple access (MC-FDMA) systems. CDMA can be implemented using radio technologies such as Universal Terrestrial Radio Access (UTRA) or CDMA2000. TDMA can be implemented using radio technologies such as Global System for Mobile Communications (GSM), General Packet Radio Service (GPRS), or Enhanced Data Rates for GSM Evolution (EDGE). OFDMA can be implemented using radio technologies such as Institute of Electrical and Electronics Engineers (IEEE) 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802.20, or Evolved UTRA (E-UTRA). UTRA is part of Universal Mobile Telecommunications System (UMTS). 3rd Generation Partnership Project (3GPP) Long Term Evolution (LTE) is part of Evolved UMTS (E-UMTS) using E-UTRA. 3GPP LTE adopts OFDMA in DL and SC-FDMA in UL. LTE-Advanced (LTE-A) is an evolved version of 3GPP LTE.

[0033] For ease of description, the implementation of the present disclosure will be primarily described with respect to a 3GPP-based wireless communication system. However, the technical features of the present disclosure are not limited thereto. For example, although the following detailed description is given based on a mobile communication system corresponding to a 3GPP-based wireless communication system, aspects of the present disclosure that are not limited to 3GPP-based wireless communication systems are applicable to other mobile communication systems.

[0034] For terms and techniques not specifically described in the terms and techniques adopted in the present disclosure, reference may be made to wireless communication standard documents issued prior to the present disclosure.

[0035] In the present disclosure, "A or B" may mean "only A", "only B", or "both A and B". In other words, in the present disclosure, "A or B" may be interpreted as "A and / or B". For example, in the present disclosure, "A, B, or C" may mean "only A", "only B", "only C", or "any combination of A, B, and C".

[0036] In the present disclosure, a slash ( / ) or a comma (,) may mean "and / or". For example, "A / B" may mean "A and / or B". Thus, "A / B" may mean "only A", "only B", or "both A and B". For example, "A, B, C" may mean "A, B, or C".

[0037] In the present disclosure, “at least one of A and B” may mean “only A”, “only B”, or “both A and B”. In addition, the expression “at least one of A or B” or “at least one of A and / or B” in the present disclosure may be interpreted as being the same as “at least one of A and B”.

[0038] In addition, in the present disclosure, “at least one of A, B, and C” may mean “only A,” “only B,” “only C,” or “any combination of A, B, and C.” In addition, “at least one of A, B, or C” or “at least one of A, B, and / or C” may mean “at least one of A, B, and C.”

[0039] In addition, the brackets used in the present disclosure may mean "for example". In detail, when "control information (PDCCH)" is shown, "PDCCH" may be proposed as an example of "control information". In other words, in the present disclosure, "control information" is not limited to "PDCCH", and "PDDCH" may be proposed as an example of "control information". In addition, even when "control information (i.e., PDCCH)" is shown, "PDCCH" may be proposed as an example of "control information".

[0040] The technical features described separately in one figure in this disclosure can be implemented separately or simultaneously.

[0041] Although not limited thereto, the various descriptions, functions, processes, suggestions, methods and / or operational flowcharts of the present disclosure disclosed herein may be applied to various fields requiring wireless communication and / or connectivity between devices (e.g., 5G).

[0042] Hereinafter, the present disclosure will be described in more detail with reference to the accompanying drawings. Unless otherwise specified, the same reference numerals in the following drawings and / or descriptions may refer to the same and / or corresponding hardware blocks, software blocks and / or functional blocks.

[0043] Figure 1 An example of a communication system to which an implementation of the present disclosure is applied is shown.

[0044] exist Figure 1 The 5G usage scenarios shown in the present disclosure are only exemplary, and the technical features of the present disclosure can be applied to Figure 1 Other 5G usage scenarios shown in .

[0045] The three main demand categories for 5G include: (1) enhanced mobile broadband (eMBB) category, (2) massive machine type communication (mMTC) category, and (3) ultra-reliable and low-latency communication (URLLC) category.

[0046] Some use cases may require multiple categories for optimization, while others may focus on just one key performance indicator (KPI). 5G supports such a variety of use cases using a flexible and reliable approach.

[0047] eMBB goes far beyond basic mobile internet access and covers rich two-way work and media and entertainment applications in the cloud and augmented reality. Data is one of the core driving forces of 5G, and for the first time in the 5G era, dedicated voice services may not be provided. In 5G, voice is expected to be simply processed as an application using the data connection provided by the communication system. The main reasons for the increase in service capacity are the increase in content size and the increase in the number of applications requiring high data transmission rates. As more and more devices connect to the internet, streaming services (audio and video), conversational video, and mobile internet access will become more widely used. Many of these applications require always-on connectivity to push real-time information and alerts to users. Cloud storage and applications are rapidly increasing in mobile communication platforms and can be applied to both work and entertainment. Cloud storage is a special use case that is accelerating the growth of uplink data transmission rates. 5G is also used for remote work in the cloud. When using tactile interfaces, 5G requires much lower end-to-end latency to maintain a good user experience. Entertainment, such as cloud gaming and video streaming, is another core element that is increasing the demand for mobile broadband capabilities. Entertainment is essential for smartphones and tablets anywhere, including in highly mobile environments such as trains, cars, and airplanes. Another use case is augmented reality for entertainment and information search. In this case, augmented reality requires very low latency and instantaneous data capacity.

[0048] Furthermore, one of the most anticipated 5G use cases involves the ability to seamlessly connect embedded sensors across all fields, known as mMTC. It is expected that the number of potential Internet of Things (IoT) devices will reach 204 billion by 2020. Industrial IoT is one of the key categories that will play a major role in enabling smart cities, asset tracking, smart utilities, agriculture, and security infrastructure through 5G.

[0049] URLLC, which includes remote control and ultra-reliable / available low-latency links over the primary infrastructure, will transform new industrial services (such as autonomous vehicles). This level of reliability and latency is necessary to control smart grids, automate industry, enable robotics, and control and coordinate drones.

[0050] 5G is a means of providing streams estimated to be hundreds of megabits per second to gigabits per second, and can supplement fiber to the home (FTTH) and cable-based broadband (or DOCSIS). Such fast speeds are needed to deliver TV with a resolution of 4K or more (6K, 8K and more), as well as virtual reality and augmented reality. Virtual reality (VR) and augmented reality (AR) applications include almost immersive sports games. Specific applications may require special network configurations. For example, for VR games, game companies need to merge core servers into the network operator's edge network servers to minimize latency.

[0051] Automobiles, along with their numerous use cases for mobile communications, are expected to be a significant new driver for 5G. For example, passenger entertainment will require high simultaneous capacity and mobile broadband with high mobility. This is because future users will continue to expect high-quality connectivity, regardless of their location and speed. Another use case in the automotive sector is augmented reality (AR) dashboards. AR dashboards allow drivers to identify objects in the dark, in addition to those visible through the front window, and display distance to and movement of objects by overlaying information spoken to the driver. In the future, wireless modules will enable communication between vehicles, information exchange between vehicles and supporting infrastructure, and information exchange between vehicles and other connected devices (e.g., devices accompanying pedestrians). Safety systems will guide alternative routes, enabling drivers to drive more safely and thus reducing the risk of accidents. The next stage will be remotely controlled or autonomous vehicles. This requires extremely high reliability and extremely fast communication between autonomous vehicles and between vehicles and infrastructure. In the future, autonomous vehicles will perform all driving activities, and drivers will only focus on unusual traffic events that the vehicle cannot identify. The technical requirements for autonomous vehicles require ultra-low latency and ultra-high reliability, increasing traffic safety to a level that cannot be achieved by humans.

[0052] Smart cities and smart homes / buildings, often referred to as smart societies, will be embedded in high-density wireless sensor networks. Distributed networks of smart sensors will identify conditions for cost- and energy-efficient maintenance in cities or homes. Similar configurations can be implemented for corresponding homes. All temperature sensors, window and heating controls, burglar alarms, and household appliances will be wirelessly connected. Many of these sensors are typically low in terms of data transmission rate, power, and cost. However, certain types of devices may require real-time HD video for monitoring.

[0053] The consumption and distribution of energy, including heat and gas, is becoming increasingly distributed, necessitating the automated control of distribution sensor networks. Smart grids collect information and use digital information and communication technologies to connect sensors to each other, thereby acting upon this information. Because this information can include the behavior of both supply companies and consumers, smart grids can improve the distribution of fuels such as electricity through methods that enhance efficiency, reliability, economic viability, sustainable production, and automation. Smart grids can also be considered another sensor network with low latency.

[0054] Mission-critical applications (e.g., e-health) are one of the 5G use cases. The health sector includes many applications that can benefit from mobile communications. Communication systems can support telemedicine, which provides clinical treatment in remote locations. Telemedicine can help reduce the barriers of distance and improve access to medical services that are not continuously available in remote rural areas. Telemedicine is also used to perform important treatments and save lives in emergency situations. Wireless sensor networks based on mobile communications can provide remote monitoring and sensors for parameters such as heart rate and blood pressure.

[0055] Wireless and mobile communications are becoming increasingly important in industrial applications. Cabling is expensive to install and maintain. Therefore, the potential to replace cables with reconfigurable wireless links presents an attractive opportunity in many industrial sectors. However, to achieve this replacement, wireless connections must have similar latency, reliability, and capacity to cables, and their management must be simplified. When it comes to 5G connectivity, low latency and a very low probability of error are new requirements.

[0056] Logistics and freight tracking are important use cases for mobile communications, allowing inventory and packages to be tracked anywhere using location-based information systems. Logistics and freight tracking use cases typically require low data rates but require location information with wide range and reliability.

[0057] Reference Figure 1 , the communication system 1 includes wireless devices 100a to 100f, a base station (BS) 200, and a network 300. Figure 1 A 5G network is illustrated as an example of the network of the communication system 1 , but implementations of the present disclosure are not limited to the 5G system and may be applied to future communication systems other than the 5G system.

[0058] BS 200 and network 300 may be implemented as wireless devices, and certain wireless devices may operate as BSs / network nodes relative to other wireless devices.

[0059] Wireless devices 100a to 100f represent devices that perform communication using a radio access technology (RAT) (e.g., 5G New RAT (NR) or LTE) and may be referred to as communication / wireless / 5G devices. Wireless devices 100a to 100f may include, but are not limited to, a robot 100a, vehicles 100b-1 and 100b-2, an extended reality (XR) device 100c, a handheld device 100d, a home appliance 100e, an IoT device 100f, and an artificial intelligence (AI) device / server 400. For example, a vehicle may include a vehicle with wireless communication capabilities, an autonomous vehicle, and a vehicle capable of performing communication between vehicles. A vehicle may include an unmanned aerial vehicle (UAV) (e.g., a drone). XR devices may include AR / VR / mixed reality (MR) devices and may be implemented in the form of a head-mounted device (HMD), a head-up display (HUD) installed in a vehicle, a television, a smartphone, a computer, a wearable device, a home appliance device, a digital signage, a vehicle, a robot, and the like. Handheld devices can include smartphones, smart tablets, wearable devices (e.g., smart watches or smart glasses), and computers (e.g., laptops). Home appliances can include TVs, refrigerators, and washing machines. IoT devices can include sensors and smart meters.

[0060] In the present disclosure, wireless devices 100a to 100f may be referred to as user equipment (UE). For example, UE may include a cellular phone, a smartphone, a laptop computer, a digital broadcast terminal, a personal digital assistant (PDA), a portable multimedia player (PMP), a navigation system, a tablet-shaped personal computer (PC), a tablet PC, an ultrabook, a vehicle, a vehicle with an autonomous driving function, a connected car, a UAV, an AI module, a robot, an AR device, a VR device, an MR device, a hologram device, a public safety device, an MTC device, an IoT device, a medical device, a Fintech device (or a financial device), a security device, a weather / environmental device, a device related to 5G services, or a device related to the fourth industrial evolution field.

[0061] A UAV may be, for example, an aerial vehicle that is piloted by wireless control signals without a human on board.

[0062] VR devices may include, for example, devices for realizing objects or backgrounds in a virtual world. AR devices may include, for example, devices that realize this by connecting objects or backgrounds in a virtual world to objects or backgrounds in the real world. MR devices may include, for example, devices that realize this by merging objects or backgrounds in a virtual world into objects or backgrounds in the real world. Hologram devices may include, for example, devices for realizing 360-degree stereoscopic images by recording and reproducing stereoscopic information, which uses the interference phenomenon of light generated when two lasers meet, known as holographic imaging.

[0063] Public safety devices may include, for example, image relay devices or image devices wearable on a user's body.

[0064] MTC devices and IoT devices may be devices that do not require direct human intervention or manipulation, for example, and may include smart meters, vending machines, thermometers, smart light bulbs, door locks, or various sensors.

[0065] A medical device may be, for example, a device used for the purpose of diagnosing, treating, alleviating, curing, or preventing a disease. For example, a medical device may be a device used for the purpose of diagnosing, treating, alleviating, or correcting an injury or damage. For example, a medical device may be a device used for the purpose of inspecting, replacing, or modifying a structure or function. For example, a medical device may be a device used for the purpose of regulating pregnancy. For example, a medical device may include a device for treatment, a device for operation, a device for (in vitro) diagnosis, a hearing aid, or a device for surgery.

[0066] The safety device may be, for example, a device installed to prevent possible danger and maintain safety. For example, the safety device may be a camera, a closed-circuit TV (CCTV), a recorder, or a black box.

[0067] A Fintech device may be, for example, a device that can provide financial services such as mobile payments. For example, a Fintech device may include a payment device or a point of sale (POS) system.

[0068] Weather / environmental devices may include, for example, devices for monitoring or predicting weather / environmental conditions.

[0069] Wireless devices 100a to 100f can connect to network 300 via BS 200. AI technology can be applied to wireless devices 100a to 100f, and wireless devices 100a to 100f can connect to AI server 400 via network 300. Network 300 can be configured using 3G networks, 4G (e.g., LTE) networks, 5G (e.g., NR) networks, and beyond 5G networks. Although wireless devices 100a to 100f can communicate with each other via BS 200 / network 300, wireless devices 100a to 100f can perform direct communication (e.g., sidelink communication) with each other without going through BS 200 / network 300. For example, vehicles 100b-1 and 100b-2 can perform direct communication (e.g., vehicle-to-vehicle (V2V) / vehicle-to-everything (V2X) communication). IoT devices (e.g., sensors) can perform direct communication with other IoT devices (e.g., sensors) or other wireless devices 100a to 100f.

[0070] Wireless communications / connections 150a, 150b, and 150c may be established between wireless devices 100a to 100f and / or between wireless devices 100a to 100f and BS 200 and / or between BSs 200. Herein, wireless communications / connections may be established via various RATs (e.g., 5G NR), such as uplink / downlink communication 150a, sidelink communication (or device-to-device (D2D) communication) 150b, and inter-base station communication 150c (e.g., relay, integrated access and backhaul (IAB)). Wireless devices 100a to 100f and BS 200 / wireless devices 100a to 100f may transmit / receive radio signals to / from each other via wireless communications / connections 150a, 150b, and 150c. For example, wireless communications / connections 150a, 150b, and 150c may transmit / receive signals via various physical channels. To this end, various configuration information configuration processes for sending / receiving radio signals, various signal processing processes (e.g., channel coding / decoding, modulation / demodulation, and resource mapping / demapping), and at least a portion of the resource allocation process can be performed based on the various proposals of the present disclosure.

[0071] Here, the radio communication technology implemented in the wireless device in the present disclosure may include narrowband Internet of Things (NB-IoT) technology for low-power communication as well as LTE, NR and 6G. For example, NB-IoT technology may be an example of low-power wide area network (LPWAN) technology, may be implemented in specifications such as LTE Cat NB1 and / or LTE Cat NB2, and may not be limited to the above names. Additionally and / or alternatively, the radio communication technology implemented in the wireless device in the present disclosure may communicate based on LTE-M technology. For example, LTE-M technology may be an example of LPWAN technology and may be referred to as various names such as enhanced machine type communication (eMTC). For example, LTE-M technology may be implemented in at least one of various specifications such as 1) LTE Cat 0, 2) LTE Cat M1, 3) LTE Cat M2, 4) LTE non-bandwidth limited (non-BL), 5) LTE-MTC, 6) LTE machine type communication, and / or 7) LTE M, and may not be limited to the above names. Additionally and / or alternatively, the radio communication technology implemented in the wireless device of the present disclosure may include at least one of ZigBee, Bluetooth, and / or LPWAN considering low-power communication, and may not be limited to the above names. For example, ZigBee technology can generate a personal area network (PAN) associated with small / low-power digital communication based on various specifications such as IEEE 802.15.4, and may be referred to by various names.

[0072] Figure 2An example of a wireless device to which an implementation of the present disclosure is applied is shown.

[0073] Reference Figure 2 , the first wireless device 100 and the second wireless device 200 can transmit / receive radio signals to / from an external device through various RATs (eg, LTE and NR). Figure 2 In the example, {first wireless device 100 and second wireless device 200} may correspond to the attached Figure 1 At least one of {wireless devices 100a to 100f and BS200}, {wireless devices 100a to 100f and wireless devices 100a to 100f} and / or {BS200 and BS200}.

[0074] The first wireless device 100 may include one or more processors 102 and one or more memories 104, and may also include one or more transceivers 106 and / or one or more antennas 108. The processor 102 may control the memory 104 and / or the transceiver 106 and may be configured to implement the descriptions, functions, processes, suggestions, methods, and / or operational flowcharts described in this disclosure. For example, the processor 102 may process information within the memory 104 to generate first information / signals, and then transmit a radio signal including the first information / signals through the transceiver 106. The processor 102 may receive a radio signal including second information / signals through the transceiver 106, and then store information obtained by processing the second information / signals in the memory 104. The memory 104 may be connected to the processor 102 and may store various information related to the operation of the processor 102. For example, the memory 104 may store software code including commands for executing part or all of the processes controlled by the processor 102 or for executing the descriptions, functions, processes, suggestions, methods, and / or operational flowcharts described in this disclosure. In this document, the processor 102 and the memory 104 may be part of a communication modem / circuit / chip designed to implement a RAT (e.g., LTE or NR). The transceiver 106 may be connected to the processor 102 and transmit and / or receive radio signals via one or more antennas 108. Each of the transceivers 106 may include a transmitter and / or a receiver. The transceiver 106 may be used interchangeably with a radio frequency (RF) unit. In this disclosure, the first wireless device 100 may represent a communication modem / circuit / chip.

[0075] The second wireless device 200 may include one or more processors 202 and one or more memories 204, and may also include one or more transceivers 206 and / or one or more antennas 208. The processor 202 may control the memory 204 and / or the transceiver 206 and may be configured to implement the descriptions, functions, processes, suggestions, methods, and / or operational flowcharts described in this disclosure. For example, the processor 202 may process information within the memory 204 to generate third information / signals, and then transmit a radio signal including the third information / signals through the transceiver 206. The processor 202 may receive a radio signal including fourth information / signals through the transceiver 106, and then store information obtained by processing the fourth information / signals in the memory 204. The memory 204 may be connected to the processor 202 and may store various information related to the operation of the processor 202. For example, the memory 204 may store software code including commands for executing part or all of the processes controlled by the processor 202 or for executing the descriptions, functions, processes, suggestions, methods, and / or operational flowcharts described in this disclosure. Herein, the processor 202 and the memory 204 may be part of a communication modem / circuit / chip designed to implement a RAT (e.g., LTE or NR). The transceiver 206 may be connected to the processor 202 and transmit and / or receive radio signals via one or more antennas 208. Each of the transceivers 206 may include a transmitter and / or a receiver. The transceiver 206 may be used interchangeably with an RF unit. In the present disclosure, the second wireless device 200 may represent a communication modem / circuit / chip.

[0076] In the following, the hardware elements of the wireless devices 100 and 200 will be described in more detail. One or more protocol layers may be implemented by, but not limited to, one or more processors 102 and 202. For example, one or more processors 102 and 202 may implement one or more layers (e.g., functional layers such as a physical (PHY) layer, a medium access control (MAC) layer, a radio link control (RLC) layer, a packet data convergence protocol (PDCP) layer, a radio resource control (RRC) layer, and a service data adaptation protocol (SDAP) layer). According to the descriptions, functions, processes, suggestions, methods, and / or operational flowcharts disclosed in the present disclosure, one or more processors 102 and 202 may generate one or more protocol data units (PDUs) and / or one or more service data units (SDUs). One or more processors 102 and 202 may generate messages, control information, data, or information according to the descriptions, functions, processes, suggestions, methods, and / or operational flowcharts disclosed in the present disclosure. The one or more processors 102 and 202 may generate a signal (e.g., a baseband signal) including a PDU, an SDU, a message, control information, data, or information according to the description, functions, procedures, suggestions, methods, and / or operational flowcharts disclosed in the present disclosure, and provide the generated signal to the one or more transceivers 106 and 206. The one or more processors 102 and 202 may receive a signal (e.g., a baseband signal) from the one or more transceivers 106 and 206, and obtain the PDU, SDU, message, control information, data, or information according to the description, functions, procedures, suggestions, methods, and / or operational flowcharts disclosed in the present disclosure.

[0077] One or more processors 102 and 202 may be referred to as controllers, microcontrollers, microprocessors, or microcomputers. One or more processors 102 and 202 may be implemented by hardware, firmware, software, or a combination thereof. 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 one or more processors 102 and 202. The descriptions, functions, processes, suggestions, methods, and / or operational flowcharts disclosed in this disclosure may be implemented using firmware or software, and the firmware or software may be configured to include modules, processes, or functions. Firmware or software configured to execute the descriptions, functions, processes, suggestions, methods, and / or operational flowcharts disclosed in this disclosure may be included in one or more processors 102 and 202, or stored in one or more memories 104 and 204, thereby being driven by one or more processors 102 and 202. The descriptions, functions, processes, suggestions, methods and / or operational flowcharts disclosed in this disclosure may be implemented using firmware or software in the form of codes, commands and / or command sets.

[0078] One or more memories 104 and 204 can be connected to one or more processors 102 and 202 and store various types of data, signals, messages, information, programs, codes, instructions and / or commands. One or more memories 104 and 204 can be configured by read-only memory (ROM), random access memory (RAM), electrically erasable programmable read-only memory (EPROM), flash memory, hard drive, registers, cache memory, computer-readable storage media and / or combinations thereof. One or more memories 104 and 204 can be located internally and / or externally to one or more processors 102 and 202. One or more memories 104 and 204 can be connected to one or more processors 102 and 202 by various technologies such as wired or wireless connections.

[0079] One or more transceivers 106 and 206 can transmit user data, control information, and / or radio signals / channels mentioned in the descriptions, functions, processes, suggestions, methods, and / or operational flowcharts disclosed in this disclosure to one or more other devices. One or more transceivers 106 and 206 can receive user data, control information, and / or radio signals / channels mentioned in the descriptions, functions, processes, suggestions, methods, and / or operational flowcharts disclosed in this disclosure from one or more other devices. For example, one or more transceivers 106 and 206 can be connected to one or more processors 102 and 202 and transmit and receive radio signals. For example, one or more processors 102 and 202 can perform control so that one or more transceivers 106 and 206 can transmit user data, control information, or radio signals to one or more other devices. One or more processors 102 and 202 can perform control so that one or more transceivers 106 and 206 can receive user data, control information, or radio signals from one or more other devices.

[0080] One or more transceivers 106 and 206 may be connected to one or more antennas 108 and 208, and the one or more transceivers 106 and 206 may be configured to transmit and receive user data, control information, and / or radio signals / channels mentioned in the descriptions, functions, processes, suggestions, methods, and / or operational flowcharts disclosed in the present disclosure through the one or more antennas 108 and 208. In the present disclosure, the one or more antennas may be multiple physical antennas or multiple logical antennas (e.g., antenna ports).

[0081] One or more transceivers 106 and 206 may convert received radio signals / channels, etc., from RF band signals to baseband signals in order to process received user data, control information, radio signals / channels, etc. One or more transceivers 106 and 206 may convert user data, control information, radio signals / channels, etc., processed using one or more processors 102 and 202, from baseband signals to RF band signals. To this end, one or more transceivers 106 and 206 may include (analog) oscillators and / or filters. For example, under the control of processors 102 and 202, transceivers 106 and 206 may up-convert an OFDM baseband signal to a carrier frequency using their (analog) oscillators and / or filters, and transmit the up-converted OFDM signal at the carrier frequency. Transceivers 106 and 206 may receive an OFDM signal at a carrier frequency and, under the control of processors 102 and 202, down-convert the OFDM signal to an OFDM baseband signal using their (analog) oscillators and / or filters.

[0082] In implementations of the present disclosure, a UE may operate as a transmitting device in the uplink (UL) and as a receiving device in the downlink (DL). In implementations of the present disclosure, a base station (BS) may operate as a receiving device in the UL and as a transmitting device in the DL. Hereinafter, for ease of description, it is primarily assumed that the first wireless device 100 acts as a UE and the second wireless device 200 acts as a base station (BS). For example, the processor 102 connected to, installed on, or activated in the first wireless device 100 may be configured to perform UE behavior according to implementations of the present disclosure, or to control the transceiver 106 to perform UE behavior according to implementations of the present disclosure. The processor 202 connected to, installed on, or activated in the second wireless device 200 may be configured to perform BS behavior according to implementations of the present disclosure, or to control the transceiver 206 to perform BS behavior according to implementations of the present disclosure.

[0083] In this disclosure, a BS is also referred to as a Node B (NB), an eNodeB (eNB), or a gNB.

[0084] Figure 3 An example of a wireless device to which an implementation of the present disclosure is applied is shown.

[0085] The wireless device may be implemented in various forms depending on the use case / service (see Figure 1 ).

[0086] Reference Figure 3 , the wireless devices 100 and 200 may correspond to Figure 2 The wireless devices 100 and 200 may be configured by various elements, components, units / parts and / or modules. For example, each of the wireless devices 100 and 200 may include a communication unit 110, a control unit 120, a memory unit 130 and an additional component 140. The communication unit 110 may include a communication circuit 112 and a transceiver 114. For example, the communication circuit 112 may include Figure 2 One or more processors 102 and 202 and / or Figure 2 One or more memories 104 and 204. For example, the transceiver 114 may include Figure 2 One or more transceivers 106 and 206 and / or Figure 2The control unit 120 is electrically connected to the communication unit 110, the memory unit 130, and the additional components 140, and controls the overall operation of each of the wireless devices 100 and 200. For example, the control unit 120 can control the electrical / mechanical operation of each of the wireless devices 100 and 200 based on the program / code / command / information stored in the memory unit 130. The control unit 120 can transmit information stored in the memory unit 130 to the outside (e.g., other communication devices) through a wireless / wired interface via the communication unit 110, or store information received from the outside (e.g., other communication devices) through a wireless / wired interface in the memory unit 130 via the communication unit 110.

[0087] The additional component 140 may be configured differently depending on the type of the wireless devices 100 and 200. For example, the additional component 140 may include at least one of a power supply unit / battery, an input / output (I / O) unit (e.g., an audio I / O port, a video I / O port), a driving unit, and a computing unit. The wireless devices 100 and 200 may be configured in the form of, but not limited to, robots ( Figure 1 100a), vehicles ( Figure 1 100b-1 and 100b-2), XR devices ( Figure 1 100c), handheld device ( Figure 1 100d), household appliances ( Figure 1 100e), IoT devices ( Figure 1 100f), digital broadcast terminal, hologram device, public safety device, MTC device, medical device, Fintech device (or financial device), security device, climate / environmental device, AI server / device ( Figure 1 400), BSS( Figure 1 The wireless devices 100 and 200 may be implemented in the form of a mobile or fixed location, depending on the use case / service.

[0088] exist Figure 3In the wireless devices 100 and 200, the various elements, components, units / parts, and / or modules in their entirety may be connected to each other via a wired interface, or at least a portion thereof may be wirelessly connected via the communication unit 110. For example, in each of the wireless devices 100 and 200, the control unit 120 and the communication unit 110 may be connected via a wired interface, and the control unit 120 and the first unit (e.g., 130 and 140) may be wirelessly connected via the communication unit 110. Each element, component, unit / part, and / or module within the wireless devices 100 and 200 may also include one or more elements. For example, the control unit 120 may be configured by a group of one or more processors. As an example, the control unit 120 may be configured by a group of a communication control processor, an application processor (AP), an electronic control unit (ECU), a graphics processing unit, and a memory control processor. As another example, the memory unit 130 may be configured by RAM, DRAM, ROM, flash memory, volatile memory, non-volatile memory, and / or a combination thereof.

[0089] Figure 4 Another example of a wireless device to which implementations of the present disclosure are applied is shown.

[0090] Reference Figure 4 , the wireless devices 100 and 200 may correspond to Figure 2 The wireless devices 100 and 200 may be configured by various elements, components, units / portions and / or modules.

[0091] First wireless device 100 may include at least one transceiver, such as transceiver 106, and at least one processing chip, such as processing chip 101. Processing chip 101 may include at least one processor, such as processor 102, and at least one memory, such as memory 104. Memory 104 may be operably connected to processor 102. Memory 104 may store various types of information and / or instructions. Memory 104 may store software code 105 that, when executed by processor 102, implements instructions for performing the descriptions, functions, procedures, suggestions, methods, and / or operational flowcharts disclosed in this disclosure. For example, software code 105 may implement instructions for performing the descriptions, functions, procedures, suggestions, methods, and / or operational flowcharts disclosed in this disclosure, when executed by processor 102. For example, software code 105 may control processor 102 to execute one or more protocols. For example, software code 105 may control processor 102 to execute one or more layers of a radio interface protocol.

[0092] The second wireless device 200 may include at least one transceiver, such as transceiver 206, and at least one processing chip, such as processing chip 201. Processing chip 201 may include at least one processor, such as processor 202, and at least one memory, such as memory 204. Memory 204 may be operably connected to processor 202. Memory 204 may store various types of information and / or instructions. Memory 204 may store software code 205 that, when executed by processor 202, implements instructions for performing the descriptions, functions, procedures, suggestions, methods, and / or operational flowcharts disclosed in this disclosure. For example, software code 205 may implement instructions for performing the descriptions, functions, procedures, suggestions, methods, and / or operational flowcharts disclosed in this disclosure, when executed by processor 202. For example, software code 205 may control processor 202 to execute one or more protocols. For example, software code 205 may control processor 202 to execute one or more layers of a wireless interface protocol.

[0093] Figure 5 An example of a UE to which an implementation of the present disclosure is applied is shown.

[0094] Reference Figure 5 , UE 100 may correspond to the attached Figure 2 The first wireless device 100 and / or Figure 4 The first wireless device 100 is configured to:

[0095] UE 100 includes a processor 102 , memory 104 , a transceiver 106 , one or more antennas 108 , a power management module 110 , a battery 112 , a display 114 , a keypad 116 , a subscriber identity module (SIM) card 118 , a speaker 120 , and a microphone 122 .

[0096] The processor 102 may be configured to implement the descriptions, functions, processes, suggestions, methods, and / or operational flowcharts disclosed in the present disclosure. The processor 102 may be configured to control one or more other components of the UE 100 to implement the descriptions, functions, processes, suggestions, methods, and / or operational flowcharts disclosed in the present disclosure. The layers of the radio interface protocol may be implemented in the processor 102. The processor 102 may include an ASIC, other chipsets, logic circuits, and / or data processing devices. The processor 102 may be an application processor. The processor 102 may include at least one of a digital signal processor (DSP), a central processing unit (CPU), a graphics processing unit (GPU), and a modem (modulator and demodulator). Examples of the processor 102 may be found at SNAPDRAGON MANUFACTURED TM series processors, Manufactured by EXYNOSTM series processors, A series processors manufactured by HELIO manufactured TM series processors, ATOM manufactured TM series processors or corresponding to the next generation processors.

[0097] The memory 104 is operatively coupled to the processor 102 and stores a variety of information to operate the processor 102. The memory 104 may include ROM, RAM, flash memory, a memory card, a storage medium, and / or other storage devices. When the embodiment is implemented in software, the techniques described herein may be implemented with modules (e.g., processes, functions, etc.) that execute the descriptions, functions, processes, suggestions, methods, and / or operational flow charts disclosed in this disclosure. The modules may be stored in the memory 104 and executed by the processor 102. The memory 104 may be implemented within the processor 102 or external to the processor 102, in which case the memory 104 may be communicatively coupled to the processor 102 via various means known in the art.

[0098] The transceiver 106 is operatively coupled to the processor 102 and transmits and / or receives radio signals. The transceiver 106 includes a transmitter and a receiver. The transceiver 106 may include baseband circuitry for processing radio frequency signals. The transceiver 106 controls one or more antennas 108 to transmit and / or receive radio signals.

[0099] The power management module 110 manages power to the processor 102 and / or the transceiver 106. The power management module 110 is powered by a battery 112.

[0100] The display 114 outputs the results processed by the processor 102. The keypad 116 receives input to be used by the processor 102. The keypad 116 may be displayed on the display 114.

[0101] The SIM card 118 is an integrated circuit designed to securely store an International Mobile Subscriber Identity (IMSI) number and its associated keys, which are used to identify and authenticate subscribers on mobile telephony devices such as mobile phones and computers. Contact information can also be stored on many SIM cards.

[0102] The speaker 120 outputs sound-related results processed by the processor 102. The microphone 122 receives sound-related input to be used by the processor 102.

[0103] Figure 6 and Figure 7 An example of a protocol stack in a 3GPP-based wireless communication system to which implementations of the present disclosure are applied is shown.

[0104] Specifically, Figure 6 illustrates an example of a radio interface user plane protocol stack between a UE and a BS, and Figure 7 An example of a radio interface control plane protocol stack between a UE and a BS is illustrated. The control plane refers to a path through which control messages for managing calls between the UE and the network are transmitted. The user plane refers to a path through which data generated in the application layer (for example, voice data or Internet packet data) is transmitted. Figure 6 , the user plane protocol stack can be divided into layer 1 (ie, PHY layer) and layer 2. Figure 7 , the control plane protocol stack can be divided into layer 1 (ie, PHY layer), layer 2, layer 3 (eg, RRC layer) and non-access stratum (NAS) layer. Layer 1, layer 2 and layer 3 are called access stratum (AS).

[0105] In 3GPP LTE systems, Layer 2 is divided into the following sublayers: MAC, RLC, and PDCP. In 3GPP NR systems, Layer 2 is divided into the following sublayers: MAC, RLC, PDCP, and SDAP. The PHY layer provides transport channels to the MAC sublayer, the MAC sublayer provides logical channels to the RLC sublayer, the RLC sublayer provides RLC channels to the PDCP sublayer, and the PDCP sublayer provides radio bearers to the SDAP sublayer. The SDAP sublayer provides Quality of Service (QoS) flows to the 5G core network.

[0106] In 3GPP NR systems, the main services and functions of the MAC sublayer include: mapping between logical channels and transport channels; multiplexing / demultiplexing MAC SDUs belonging to one or different logical channels onto / from transport blocks (TBs) delivered to / from the physical layer on transport channels; scheduling information reporting; error correction through hybrid automatic repeat request (HARQ) (one HARQ entity per cell in the case of carrier aggregation (CA); priority handling between UEs through dynamic scheduling; priority handling between logical channels of a UE through logical channel prioritization; and padding. A single MAC entity can support multiple parameter sets, transmission timings, and cells. Mapping restrictions in logical channel prioritization control which parameter set(s), cell, and transmission timing can be used by a logical channel.

[0107] MAC provides different types of data transfer services. To accommodate different types of data transfer services, multiple types of logical channels are defined, that is, each logical channel supports the transmission of a specific type of information. Each logical channel type is defined by the type of information transmitted. Logical channels are divided into two groups: control channels and traffic channels. Control channels are used only for the transmission of control plane information, and traffic channels are used only for the transmission of user plane information. The Broadcast Control Channel (BCCH) is a downlink logical channel used to broadcast system control information, the Paging Control Channel (PCCH) is a downlink logical channel that transmits paging information, system information change notifications, and indications of ongoing Public Warning Service (PWS) broadcasts, the Common Control Channel (CCCH) is a logical channel used to send control information between the UE and the network and is used by UEs that do not have an RRC connection with the network, and the Dedicated Control Channel (DCCH) is a point-to-point bidirectional logical channel that sends dedicated control information between the UE and the network and is used by UEs with an RRC connection. The Dedicated Traffic Channel (DTCH) is a point-to-point logical channel dedicated to one UE and is used to transmit user information. The DTCH can exist in both the uplink and downlink. In the downlink, the following connections exist between logical channels and transport channels: BCCH can be mapped to the broadcast channel (BCH); BCCH can be mapped to the downlink shared channel (DL-SCH); PCCH can be mapped to the paging channel (PCH); CCCH can be mapped to DL-SCH; DCCH can be mapped to DL-SCH; and DTCH can be mapped to DL-SCH. In the uplink, the following connections exist between logical channels and transport channels: CCCH can be mapped to the uplink shared channel (UL-SCH); DCCH can be mapped to UL-SCH; and DTCH can be mapped to UL-SCH.

[0108] The RLC sublayer supports three transmission modes: transparent mode (TM), unacknowledged mode (UM), and acknowledged mode (AM). The RLC configuration is per logical channel, without dependency on parameter sets and / or transmission duration. In 3GPP NR systems, the main services and functions of the RLC sublayer depend on the transmission mode and include: delivery of upper layer PDUs; sequence numbering independent of sequence numbering in PDCP (UM and AM); error correction through ARQ (AM only); segmentation (AM and UM) and re-segmentation (AM only) of RLC SDUs; reassembly of SDUs (AM and UM); duplicate detection (AM only); RLC SDU discard (AM and UM); RLC re-establishment; protocol error detection (AM).

[0109] In the 3GPP NR system, the main services and functions of the PDCP sublayer for the user plane include: sequence numbering; header compression and decompression using Robust Header Compression (RoHC); delivery of user data; reordering and duplicate detection; in-sequence delivery; PDCP PDU routing (in the case of split bearers); retransmission of PDCP SDUs; ciphering, deciphering, and integrity protection; PDCP SDU discard; PDCP re-establishment and data recovery for RLC AM; PDCP status reporting for RLC AM; PDCP PDU duplication and duplicate discard indication to lower layers. The main services and functions of the PDCP sublayer for the control plane include: sequence numbering; ciphering, deciphering, and integrity protection; delivery of control plane data; reordering and duplicate detection; in-sequence delivery; PDCP PDU duplication and duplicate discard indication to lower layers.

[0110] In 3GPP NR systems, the main services and functions of SDAP include: mapping between QoS flows and data radio bearers; marking QoS flow IDs (QFIs) in both DL and UL packets. A single protocol entity of SDAP is configured for each individual PDU session.

[0111] In the 3GPP NR system, the main services and functions of the RRC sublayer include: broadcast of system information related to AS and NAS; paging initiated by 5GC or NG-RAN; establishment, maintenance and release of RRC connections between UE and NG-RAN; security functions including key management; establishment, configuration, maintenance and release of signaling radio bearers (SRBs) and data radio bearers (DRBs); mobility functions (including handover and context transfer, UE cell selection and reselection and control of cell selection and reselection, and inter-RAT mobility); QoS management functions; UE measurement reporting and control of reporting; detection and recovery of radio link failures; and NAS message transmission from UE to NAS / from NAS to UE.

[0112] Figure 8 The frame structure in a 3GPP-based wireless communication system to which the implementation of the present disclosure is applied is shown.

[0113] Figure 8The frame structure shown in is merely exemplary, and the number of subframes, the number of time slots, and / or the number of symbols in a frame may vary. In a 3GPP-based wireless communication system, OFDM parameter sets (e.g., subcarrier spacing (SCS), transmission time interval (TTI) duration) may be configured differently between multiple cells aggregated for one UE. For example, if a UE is configured with different SCSs for cells aggregated for a cell, the (absolute time) duration of time resources (e.g., subframes, time slots, or TTIs) comprising the same number of symbols may be different among the aggregated cells. In this document, the symbols may include OFDM symbols (or CP-OFDM symbols), SC-FDMA symbols (or discrete Fourier transform-spread-OFDM (DFT-s-OFDM) symbols).

[0114] Reference Figure 8 , downlink and uplink transmissions are organized into frames. Each frame has T f = 10ms duration. Each frame is divided into two half-frames, where each half-frame has a duration of 5ms. Each half-frame includes 5 sub-frames, where the duration of each sub-frame is T sf is 1 ms. Each subframe is divided into slots, and the number of slots in a subframe depends on the subcarrier spacing. Each slot includes 14 or 12 OFDM symbols based on the cyclic prefix (CP). In normal CP, each slot includes 14 OFDM symbols, and in extended CP, each slot includes 12 OFDM symbols. The parameter set is based on an exponentially scalable subcarrier spacing Δf=2 u *15kHz.

[0115] Table 1 shows the subcarrier spacing Δf=2 u *N, the number of OFDM symbols per time slot of 15kHz slot symb , the number of time slots per frame N frame，u slot , and the number of slots N per subframe for normal CP subframe，u slot .

[0116] [Table 1]

[0117] u <![CDATA[N slot symb ]]> <![CDATA[N frame,u slot ]]> <![CDATA[N subframe，u slot ]]> 0 14 10 1 1 14 20 2 2 14 40 4 3 14 80 8 4 14 160 16

[0118] Table 2 shows the subcarrier spacing Δf=2 u *N, the number of OFDM symbols per time slot of 15kHz slot symb , the number of time slots per frame N frame，u slot , and the number of slots N per subframe for the extended CPsubframe，u slot .

[0119] [Table 2]

[0120] u <![CDATA[N slot symb ]]> <![CDATA[N frame，u slot ]]> <![CDATA[N subframe，u slot ]]> 2 12 40 4

[0121] A slot includes multiple symbols (e.g., 14 or 12 symbols) in the time domain. For each parameter set (e.g., subcarrier spacing) and carrier, a common resource block (CRB) N is allocated from the CRBs indicated by higher layer signaling (e.g., RRC signaling). start,u grid To begin, define N size,u grid，x *N RB sc subcarriers and N subframe，u symb OFDM symbol resource grid, where N size,u grid,x N is the number of resource blocks (RBs) in the resource grid, with the subscript x being DL for downlink and UL for uplink. RB sc is the number of subcarriers per RB. In 3GPP-based wireless communication systems, N RB sc Typically 12. For a given antenna port p, subcarrier spacing configuration u, and transmission direction (DL or UL), there is one resource grid. The carrier bandwidth N for subcarrier spacing configuration u is size,u grid Given by high-level parameters (e.g., RRC parameters). Each element in the resource grid for antenna port p and subcarrier spacing configuration u is called a resource element (RE), and one complex symbol can be mapped to each RE. Each RE in the resource grid is uniquely identified by an index k in the frequency domain and an index 1 representing the symbol position relative to a reference point in the time domain. In a 3GPP-based wireless communication system, an RB is defined by 12 consecutive subcarriers in the frequency domain. In a 3GPP NR system, RBs are classified into CRBs and physical resource blocks (PRBs). CRBs are numbered upward from 0 in the frequency domain for subcarrier spacing configuration u. The center of subcarrier 0 of CRB 0 for subcarrier spacing configuration u coincides with "point A" which is used as a common reference point for the resource block grid. In a 3GPP NR system, PRBs are defined within a bandwidth part (BWP) and are numbered from 0 to N. size BWP,i-1 where i is the number of the bandwidth part. Physical resource block n in bandwidth part i PRB With public resource block n CRB The relationship between them is as follows: PRB =n CRB +Nsize BWP，i , where N size BWP，i A BWP is a common resource block that begins with CRB 0. A BWP consists of multiple contiguous RBs. A carrier can include up to N (e.g., 5) BWPs. A UE can be configured with one or more BWPs on a given component carrier. Of the BWPs configured for a UE, only one can be active at a time. The active BWP defines the UE's operating bandwidth within the cell's operating bandwidth.

[0122] The NR frequency band can be defined as two types of frequency ranges, namely, FR1 and FR2. The numerical values of the frequency ranges can be changed. For example, the two types of frequency ranges (FR1 and FR2) can be shown in Table 3 below. For ease of explanation, in the frequency range used in the NR system, FR1 can represent "sub-6 GHz range", FR2 can represent "above 6 GHz range" and can be called millimeter wave (mmW).

[0123] [Table 3]

[0124] Frequency range specification Corresponding frequency range Subcarrier spacing FR1 450MHz-6000MHz 15, 30, 60kHz

[0125]

[0126] As described above, the numerical value of the frequency range of the NR system can be changed. For example, FR1 can include a frequency band of 410 MHz to 7125 MHz, as shown in Table 4 below. That is, FR1 can include a frequency band of 6 GHz (or 5850, 5900, 5925 MHz, etc.) or larger. For example, the frequency band of 6 GHz (or 5850, 5900, 5925 MHz, etc.) or larger included in FR1 can include an unlicensed frequency band. The unlicensed frequency band can be used for various purposes, such as for communication in vehicles (e.g., autonomous driving).

[0127] [Table 4]

[0128] Frequency range specification Corresponding frequency range Subcarrier spacing FR1 410MHz-7125MHz 15, 30, 60kHz FR2 24250MHz-52600MHz 60, 120, 240kHz

[0129] In this disclosure, the term "cell" can refer to a geographical area where one or more nodes provide a communication system, or to radio resources. A "cell," as a geographical area, can be understood as the coverage area within which a node can provide services using a carrier, and a "cell," as a radio resource (e.g., a time-frequency resource), is associated with a bandwidth, which is a frequency range configured by a carrier. A "cell," associated with radio resources, is defined by a combination of downlink and uplink resources (e.g., a combination of a DL component carrier (CC) and an UL component carrier (CC). A cell can be configured with downlink resources only, or with both downlink and uplink resources. Because the DL coverage (the range within which a node can transmit valid signals) and the UL coverage (the range within which a node can receive valid signals from a UE) depend on the carrier carrying the signal, the coverage of a node can be associated with the coverage of the "cell" of the radio resources used by the node. Therefore, the term "cell" can sometimes refer to the service coverage of a node, at other times to the radio resource, or at other times to the range within which a signal using the radio resource can reach with effective strength. In carrier aggregation, two or more CCs are aggregated. The UE can receive or transmit on one or more CCs simultaneously depending on its capabilities. CA is supported for both contiguous CCs and non-contiguous CCs. When CA is configured, the UE has only one RRC connection with the network. During RRC connection establishment / reestablishment / handover, one serving cell provides NAS mobility information, and during RRC connection reestablishment / handover, one serving cell provides security input. This cell is called the primary cell (PCell). The PCell is a cell operating on the primary frequency, where the UE performs the initial connection establishment process or initiates the connection reestablishment process. Depending on the UE capabilities, the secondary cell (SCell) can be configured to form a set of serving cells together with the PCell. The SCell is a cell that provides additional radio resources on top of the special cell (PCell). Therefore, the set of serving cells configured for the UE always consists of one PCell and one or more SCells. For dual connectivity (DC) operation, the term "PCell" refers to the PCell of the primary cell group (MCG) or the primary SCell (PSCell) of the secondary cell group (SCG). The SpCell supports PUCCH transmission and contention-based random access and is always activated. The MCG is the set of serving cells associated with the primary node, which includes the SpCell (PCell) and optionally one or more SCells. For UEs configured with DC, the SCG is a subset of serving cells associated with the secondary node, which includes the PSCell and zero or more SCells. For UEs in RRC_CONNECTED mode without CA / DC, there is only one serving cell consisting of the PCell.For a UE in RRC_CONNECTED with CA / DC configured, the term "serving cell" is used to refer to the set of cells consisting of the SpCell and all SCells. In DC, two MAC entities are configured in the UE: one for MCG and one for SCG.

[0130] Figure 9 An example of data flow in a 3GPP NR system to which an implementation of the present disclosure is applied is shown.

[0131] Reference Figure 9 "RB" stands for radio bearer, and "H" stands for header. Radio bearers are categorized into two groups: DRBs for user plane data and SRBs for control plane data. MAC PDUs are transmitted and received to and from external devices via the PHY layer using radio resources. MAC PDUs arrive at the PHY layer in the form of transport blocks.

[0132] In the PHY layer, the uplink transport channels UL-SCH and RACH are mapped to their physical channels PUSCH and PRACH, respectively, and the downlink transport channels DL-SCH, BCH and PCH are mapped to PDSCH, PBCH and PDSCH, respectively. In the PHY layer, uplink control information (UCI) is mapped to the physical PUCCH, and downlink control information (DCI) is mapped to the PDCCH. The MAC PDU associated with the UL-SCH is sent by the UE via the PUSCH based on the UL grant, and the MAC PDU associated with the DL-SCH is sent by the BS via the PDSCH based on the DL assignment.

[0133] During Releases 14 and 15, support for vehicle-to-vehicle (V2V) and vehicle-to-everything (V2X) services was introduced in LTE to extend the 3GPP platform to the automotive industry. These work items defined LTE sidelinks suitable for vehicular applications and complementary enhancements to the cellular infrastructure.

[0134] Further to this work, requirements have been defined in 5G LTE / NR to support enhanced V2X use cases, which are broadly arranged into four use case groups:

[0135] 1) Vehicle platooning, which enables vehicles to dynamically form a queue to travel together. All vehicles in the queue receive information from the leading vehicle to manage the queue. This information allows vehicles to drive closer than normal in a coordinated manner, going in the same direction and traveling together.

[0136] 2) Extended sensors enable the exchange of raw data, processed data, or live video images collected by local sensors among vehicles, roadside units, pedestrian devices, and V2X application servers. Vehicles can increase their awareness of their environment beyond what their own sensors can detect and gain a broader and more holistic view of the local situation. High data rates are a key feature.

[0137] 3) Advanced Driving, which enables semi-autonomous or fully autonomous driving. Each vehicle and / or RSU shares its own perception data obtained from its local sensors with neighboring vehicles, allowing vehicles to synchronize and coordinate their trajectories or maneuvers. Each vehicle also shares its driving intentions with neighboring vehicles.

[0138] 4) Remote driving, which enables a remote driver or V2X application to operate a remote vehicle whose passengers cannot drive themselves or are located in hazardous environments. Cloud-based driving can be used for situations where variables are limited and routes are predictable, such as public transportation. High reliability and low latency are key requirements.

[0139] The NR sidelink (SL) unicast, multicast, and broadcast designs are described. SL broadcast, multicast, and unicast transmissions are supported for in-coverage, out-of-coverage, and partial coverage scenarios.

[0140] Figure 10 and Figure 11 An example of a PC5 protocol stack to which an implementation of the present disclosure is applied is shown.

[0141] Figure 10 An example of a PC5 control plane (PC5-C) protocol stack between UEs is illustrated. The AS protocol stack for the control plane in the PC5 interface consists of at least an RRC sublayer, a PDCP sublayer, an RLC sublayer, a MAC sublayer, and a physical layer.

[0142] Figure 11 An example of a PC5 user plane (PC5-U) protocol stack between UEs is illustrated. The AS protocol stack for the user plane in the PC5 interface consists of at least a PDCP sublayer, an RLC sublayer, a MAC sublayer, and a physical layer.

[0143] For the purpose of physical layer analysis, it is assumed that higher layers decide whether to use unicast, multicast or broadcast transmission for a particular data transfer and they inform the physical layer accordingly. When considering unicast or multicast transmission, it is assumed that the UE is able to establish which unicast or multicast session the transmission belongs to and that the following identities are known to the physical layer:

[0144] - Layer-1 destination ID conveyed via the physical sidelink control channel (PSCCH)

[0145] - Additional Layer-1 ID conveyed via PSCCH, which serves at least the purpose of identifying which transmissions can be combined in reception when HARQ feedback is used

[0146] -HARQ process ID

[0147] For the purpose of layer 2 analysis, it is assumed that the upper layers (i.e., above the AS) provide information about whether it is for unicast, multicast, or broadcast transmission of a particular data transmission. For unicast and multicast transmissions in the SL, the following identifications are known to layer 2:

[0148] -Unicast: Destination ID, Source ID

[0149] -Multicast: destination group ID, source ID

[0150] The discovery process and related messages for unicast and multicast transmissions depend on the upper layers.

[0151] At least the following two SL resource allocation modes are defined as follows.

[0152] (1) Mode 1: The BS schedules SL resources to be used by the UE for SL transmission.

[0153] (2) Mode 2: The UE determines (ie, the BS does not schedule) SL transmission resources within pre-configured SL resources or SL resources configured by the BS / network.

[0154] The definition of SL resource allocation model 2 covers:

[0155] a) UE autonomously selects SL resources for transmission

[0156] b) UE-assisted SL resource selection for other UEs

[0157] c) The UE is configured with a grant (type 1 etc.) configured for NR transmission.

[0158] d) UE schedules SL transmission of other UEs

[0159] For SL resource allocation mode 2, sensing and resource (re)selection related procedures can be considered. The considered sensing procedure is defined as decoding sidelink control information (SCI) and / or SL measurements from other UEs. The considered resource (re)selection procedure uses the results of the sensing procedure to determine the resources for SL transmission.

[0160] For Mode 2(a), the SL sensing and resource selection process can be considered in the context of a semi-persistent scheme where resources are selected for multiple transmissions of different TBs, and a dynamic scheme where resources are selected for each TB transmission.

[0161] The following techniques can be considered to identify occupied SL resources:

[0162] -Decoding of SL control channel transmissions

[0163] -SL measurement

[0164] -SL transmission detection

[0165] Consider the following aspects for SL resource selection:

[0166] -How the UE selects resources for PSCCH and Physical Sidelink Shared Channel (PSSCH) transmissions (and other defined SL physical channels / signals)

[0167] - Which information is used by the UE for the resource selection process

[0168] Mode 2(b) is a function that can be part of the operation of Mode 2(a), (c), (d).

[0169] For out-of-coverage operation, Mode 2(c) assumes (pre-)configuration of a single or multiple SL transmission patterns defined on each SL resource pool. For in-coverage operation, Mode 2(c) assumes that the gNB configuration indicates a single or multiple SL transmission patterns defined on each SL resource pool. If there is a single pattern configured for the transmitting UE, there is no sensing process performed by the UE, whereas if multiple patterns are configured, there is the possibility of a sensing process.

[0170] The pattern is defined by the size and location of the resources in time and frequency, as well as the number of resources.

[0171] For mode 2(d), the process of becoming or acting as a scheduling UE for in-coverage and out-of-coverage scenarios may be considered as follows:

[0172] - Scheduling UE is configured by gNB

[0173] - Application layer or pre-configuration selection scheduling UE

[0174] - The receiver UE schedules the transmitter UE's transmissions during the session

[0175] - The scheduling UE is determined by a plurality of UEs including one UE that is finally selected. A UE may autonomously decide to act as a scheduling UE / provide scheduling UE functionality (ie, by self-nomination).

[0176] Until Release 15, only broadcast transmissions were supported for V2X communications. Broadcast transmissions mean that a V2X transmission from a wireless device is broadcast to several unspecified wireless devices. In the case of NR V2X, V2X communications can also support unicast and multicast transmissions, as well as broadcast transmissions. Unicast transmissions mean that a V2X transmission from a wireless device is sent to one designated other wireless device. Multicast transmissions mean that a V2X transmission from a wireless device is sent to several designated other wireless devices belonging to a group. Unicast transmissions are expected to be used for high-reliability and low-latency scenarios, such as extended sensor sharing, remote driving, and emergency situations.

[0177] In NR V2X, a wireless device can establish a PC5 link (e.g., a one-to-one connection and / or session between wireless devices) for unicast services with another wireless device. The PC5 signaling protocol above the RRC layer in the wireless device can be used for unicast link establishment and management. Based on the unicast link establishment and management, the wireless devices can exchange PC5 signaling (i.e., upper layer signaling compared to RRC signaling) to successfully or unsuccessfully establish a unicast link with security activation or release the established unicast link.

[0178] In the following, the sidelink HARQ operation is described, which may be referred to as Section 5.14.1.2 of 3GPP TS 36.321 v15.7.0.

[0179] A sidelink HARQ entity is described.

[0180] The MAC entity is configured by upper layers to transmit using a pool of resources on one or more carriers. For each carrier, there is a sidelink HARQ entity at the MAC entity for transmission on the SL-SCH, which maintains multiple parallel sidelink processes.

[0181] For V2X sidelink communications, the maximum number of transmit sidelink processes associated with each sidelink HARQ entity is 8. A sidelink process can be configured for transmission of multiple MAC PDUs. For transmission of multiple MAC PDUs, the maximum number of transmit sidelink processes associated with each sidelink HARQ entity is 2.

[0182] The delivered and configured sidelink grant and its associated HARQ information are associated with the sidelink process.

[0183] For each sidelink process and each subframe of the SL-SCH, the sidelink HARQ entity shall:

[0184] If a sidelink grant corresponding to a new transmission opportunity has been indicated for the sidelink process and there is SL data available for transmission for the sidelink logical channel of the ProSe destination associated with the sidelink grant, then:

[0185] - Get MAC PDU from the "Multiplexing and Assembly" entity;

[0186] -Deliver MAC PDU and sidelink grant and HARQ information to the sidelink process;

[0187] - Instructs the sidelink process to trigger a new transmission.

[0188] - Otherwise, if the subframe corresponds to a retransmission opportunity for the sidelink process, then:

[0189] - Instructs the sidelink process to trigger a retransmission.

[0190] Describes the sidelink process.

[0191] A sidelink process is associated with a HARQ buffer.

[0192] The sequence of redundant versions is 0, 2, 3, 1. The variable CURRENT_IRV is the index into the sequence of redundant versions. This variable is updated modulo 4.

[0193] New transmissions and retransmissions for a given SC period in sidelink communication or in V2X sidelink communication are performed on the resources indicated in the sidelink grant and with the selected MCS.

[0194] If the sidelink process is configured to perform transmission of multiple MAC PDUs for V2X sidelink communication, the process maintains a counter SL_RESOURCE_RESELECTION_COUNTER. For other configurations of the sidelink process, this counter is not available.

[0195] If the sidelink HARQ entity requests a new transmission, the sidelink process shall:

[0196] - Set CURRENT_IRV to 0;

[0197] -Store the MAC PDU in the associated HARQ buffer;

[0198] -Storing sidelink grants received from the sidelink HARQ entity;

[0199] - Generates a transmission as described below.

[0200] If the sidelink HARQ entity requests retransmission, the sidelink process shall:

[0201] - Generates a transmission as described below.

[0202] To generate a transmission, the sidelink process should:

[0203] - if there is no uplink transmission; or if the MAC entity is capable of performing transmission on the SL-SCH and uplink transmission simultaneously at the time of transmission; or if there is a MAC PDU to be sent in that TTI in the uplink in addition to the MAC PDU obtained from Msg3 and the transmission of the V2X sidelink communication takes precedence over the uplink transmission; and

[0204] - If there is no transmission on the PSDCH or no sidelink discovery gap for transmission at the time of transmission; or, in the case of transmission for V2X sidelink communication, if the MAC entity is capable of performing transmission on the SL-SCH and transmission on the PSDCH simultaneously at the time of transmission:

[0205] - Instruct the physical layer to generate a transmission with a redundancy version corresponding to the CURRENT_IRV value according to the stored sidelink grant.

[0206] -Increment CURRENT_IRV by 1;

[0207] - If the transmission corresponds to the last transmission of a MAC PDU:

[0208] - If available, decrement the SL_RESOURCE_RESELECTION_COUNTER by 1.

[0209] The transmission of MAC PDUs for V2X sidelink communication takes precedence over uplink transmissions if the following conditions are met:

[0210] - if the MAC entity is unable to perform all uplink transmissions and all V2X sidelink communications transmissions simultaneously at the time of transmission; and

[0211] - if the uplink transmission is not prioritized by upper layers; and

[0212] - If the value of the highest priority of the sidelink logical channel in the MAC-PDU is lower than thresSL-TxPrioritization (if thresSL-TxPrioritization is configured).

[0213] In the following, the Random Access Channel (RACH) procedure in NR is described.

[0214] For NR, RACH can be configured as 2-step RACH or 4-step RACH.

[0215] For 4-step RACH, the UE sends a RACH preamble, receives a random access response MAC CE, sends Message 3 on the PUSCH, and receives a contention resolution MAC CE.

[0216] For 2-step RACH, the UE sends message A consisting of a RACH preamble and PUSCH resources, and receives message B consisting of a random access response and contention resolution.

[0217] In addition, the UE can establish a unicast link and an associated PC5-RRC connection with other UEs in the sidelink.

[0218] In this case, the UE can monitor the quality of the PC5-RRC connection based on HARQ retransmissions. In this case, it is unclear how the UE declares a link failure on the PC5-RRC connection.

[0219] Therefore, there is a need for research for indicating sidelink radio link failure in wireless communication systems.

[0220] Hereinafter, a method and apparatus for indicating a sidelink radio link failure in a wireless communication system according to some embodiments of the present disclosure will be described with reference to the following drawings.

[0221] The following figures are created to explain specific embodiments of the present disclosure. The names of specific devices or the names of specific signals / messages / fields shown in the figures are provided by way of example, and therefore the technical features of the present disclosure are not limited to the specific names used in the following figures. In this document, a wireless device may be referred to as a user equipment (UE).

[0222] Figure 12 An example of a method for indicating a sidelink radio link failure in a wireless communication system according to some embodiments of the present disclosure is shown.

[0223] Specifically, Figure 12 An example of a method performed by a wireless device is shown.

[0224] In step 1201 , a first wireless device may configure a maximum number of counters for a PC5-Radio Resource Control (RRC) connection with a second wireless device.

[0225] For example, the first wireless device may establish a PC5-S unicast link and an associated PC5-RRC connection with the second wireless device.

[0226] For example, the network may send an RRC reconfiguration message to the first wireless device. The RRC reconfiguration message may include a maximum number of counters for the PC5-RRC connection with the second wireless device.

[0227] For another example, the first wireless device may configure itself the maximum number of counters for the PC5-RRC connection with the second wireless device.

[0228] For example, the first wireless device may configure a counter for each of multiple PC5-RRC connections with other wireless devices.

[0229] In step 1202 , the first wireless apparatus may initialize a counter to zero when 1) establishing a PC5-RRC connection with a second wireless apparatus or 2) configuring or reconfiguring a maximum number of the counter.

[0230] According to some embodiments of the present disclosure, the first wireless apparatus may configure another counter for another PC5-RRC connection with a third wireless apparatus.

[0231] In this case, the first wireless device may initialize another counter to zero when 1) establishing another PC5-RRC connection with the third wireless device or 2) configuring or reconfiguring the maximum number of another counter for another PC5-RRC connection with the third wireless device.

[0232] For example, the maximum number of another counter for another PC5-RRC connection with the third wireless device may be the same as the maximum number of counters for the PC5-RRC connection with the second wireless device.

[0233] For example, a maximum number of counters for a PC5-RRC connection with a second wireless device and a maximum number of another counter for a PC5-RRC connection with a third wireless device may be configured or reconfigured at the same time.

[0234] For other examples, the maximum number of another counter for another PC5-RRC connection with the third wireless device may be different from the maximum number of counters for the PC5-RRC connection with the second wireless device.

[0235] For example, a maximum number of counters for a PC5-RRC connection with a second wireless device and a maximum number of another counter for a PC5-RRC connection with a third wireless device may be independently configured or reconfigured.

[0236] In step 1203 , the first wireless device may perform transmission of a medium access control (MAC) protocol data unit (PDU) to the second wireless device based on the established PC5-RRC connection.

[0237] For example, the transmission of the MAC PDU may include a PSSCH transmission for a source Layer-2 ID of a first wireless device and a destination Layer-2-ID of a second wireless device corresponding to a pair of PC5-RRC connections.

[0238] For example, the PSSCH may carry data from the UE for sidelink communication and V2X sidelink communication.

[0239] For example, the PSCCH may be mapped to a sidelink control resource. For example, the PSCCH may indicate the resources and other transmission parameters used by the UE for the PSSCH. For V2X sidelink communications, the PSCCH and PSSCH may be transmitted in the same subframe.

[0240] In step 1204, the first wireless device may increment a counter based on not receiving any acknowledgement for the transmission of the MAC PDU.

[0241] For example, the first wireless device may monitor each physical sidelink feedback channel (PSFCH) reception opportunity associated with the transmission of the MAC PDU.Based on the absence of PSFCH reception at the PSFCH reception opportunity, the first wireless device may increment a counter.

[0242] According to some embodiments of the present disclosure, the first wireless device may reinitialize the counter to zero based on receipt of any acknowledgement of transmission of the MAC PDU.

[0243] For example, the first wireless device may monitor each PSFCH reception opportunity associated with the transmission of the MAC PDU.Based on the presence of PSFCH reception at the PSFCH reception opportunity, the first wireless device may reinitialize the counter to zero.

[0244] According to some embodiments of the present disclosure, the first wireless apparatus may be configured to reinitialize the counter to an N value of zero.

[0245] For example, the value of N is a natural number. For example, the value of N may be 1.

[0246] For example, if N acknowledgements have been received continuously or intermittently on the PSFCH, the first wireless device may reinitialize the counter to zero.

[0247] For example, the N acknowledgments may correspond to positive acknowledgments successfully received only on the PSFCH.

[0248] For example, the N acknowledgments may correspond to negative acknowledgments that were successfully received only on the PSFCH.

[0249] For example, the N acknowledgments may correspond to positive acknowledgments and negative acknowledgments successfully received on the PSFCH.

[0250] For example, the N acknowledgments may not include unsuccessful reception of any acknowledgment on the PSFCH.

[0251] In step 1205 , the first wireless device may indicate a side link (SL) radio link failure (RLF) for the PC5-RRC connection based on the counter reaching a maximum number of the counter.

[0252] According to some embodiments of the present disclosure, the first wireless device may indicate the SL RLF for the PC5-RRC connection by notifying the network of the SL RLF.

[0253] According to some embodiments of the present disclosure, a SL Hybrid Automatic Repeat Request (HARQ) entity of the first wireless device may indicate a SL RLF for a PC5-RRC connection to an RRC entity of the first wireless device.

[0254] According to some embodiments of the present disclosure, the first wireless apparatus may communicate with at least one of a user device other than the first wireless apparatus, a network, or an autonomous vehicle.

[0255] Figure 13 An example of a method for performing data transmission by a UE in a wireless communication system according to some embodiments of the present disclosure is shown.

[0256] In step 1301 , the UE may establish a unicast link and an associated PC5-RRC connection with a peer UE in a sidelink.

[0257] In step 1302, the UE may determine a maximum number of HARQ transmissions for declaring a PC5-RRC connection failure.

[0258] For example, the maximum number of HARQ transmissions used to declare PC5-RRC connection failure may be configured by the network or the peer UE.

[0259] For other examples, the UE may determine the maximum number of HARQ transmissions for declaring PC5-RRC connection failure based on QoS parameters of logical channels belonging to the PC5-RRC connection or unicast link.

[0260] In step 1303, the UE may increment the counter when one of the following conditions is met:

[0261] - if no acknowledgement (e.g., HARQ feedback) is received for the transmission of any MAC PDU; and / or

[0262] - If a negative acknowledgement has been received for the transmission of any MAC PDU.

[0263] In step 1304, the UE may reset the counter to an initial value (e.g., zero) when one of the following conditions is met:

[0264] - if parameters related to the establishment of a PC5-RRC connection or PC5-S unicast link are indicated by upper layers; and / or

[0265] - if the first new transmission is triggered by this sidelink HARQ entity for the PC5-RRC connection; and / or

[0266] - If N acknowledgements (eg, HARQ feedback) have been received consecutively or intermittently.

[0267] Figure 14 An example of a method for sidelink HARQ transmission and failure detection from a UE in a wireless communication system according to some embodiments of the present disclosure is shown.

[0268] Specifically, Figure 14 An example of sidelink HARQ transmission and failure detection from a UE according to the present disclosure is shown. However, it is clear that the present disclosure is not limited thereto. The present disclosure may also be applied to quality reporting for uplink data transmission.

[0269] In step 1401 , the TX UE may establish a PC5-S unicast link and an associated PC5-RRC connection with the RX UE.

[0270] In step 1402, the TX UE may send sidelink UE information indicating the destination ID of the RX UE to the network. The TX UE may indicate the destination ID and associated QoS information to the network via the sidelink UE information. The destination ID may be associated with a destination index based on the content of the sidelink UE information.

[0271] In step 1403, upon receiving the sidelink UE information, the network may send an RRC reconfiguration message to the TX UE. The message may include the N value and the maxHARQRetxThreshold with the destination index.

[0272] In the TX UE, for each PC5-RRC connection that has been established by RRC (or for each PC5-S unicast link established by the PC5-S entity, each destination, or each pair of source layer-2 ID and destination layer-2 ID), the sidelink HARQ entity may maintain the N value, maxHARQRetxThreshold, and MAX_RLM_ReTX_COUNT.

[0273] The N value and maxHARQRetxThreshold may be configured by RRC for a PC5-RRC connection (or a PC5-S unicast link established by a PC5-S entity, a destination, or a pair of source Layer-2 ID and destination Layer-2 ID).

[0274] The sidelink HARQ entity may correspond to both the reception sidelink HARQ entity and the transmission sidelink HARQ entity, or to the reception sidelink HARQ entity or the transmission sidelink HARQ entity.

[0275] The maxHARQRetxThreshold may be configured with the value of the maxHARQRetxThreshold configured for the logical channel with the highest priority belonging to the PC5-RRC connection or with the lowest, average or highest value of all maxHARQRetxThreshold values configured for all logical channels belonging to the PC5-RRC connection (or a PC5-S unicast link established by a PC5-S entity, a destination or a pair of source layer-2ID and destination layer-2ID).

[0276] The N value can be configured with the value of the N value configured for the logical channel with the highest priority belonging to the PC5-RRC connection or with the lowest value, average value or highest value of all N values configured for all logical channels belonging to the PC5-RRC connection (or a PC5-S unicast link established by a PC5-S entity, a destination or a pair of source layer-2ID and destination layer-2ID).

[0277] The sidelink HARQ entity in the TX UE may set MAX_RLM_ReTX_COUNT to zero for each PC5-RRC connection that has been established by RRC (or for each PC5-S unicast link established by the PC5-S entity, per destination, or per pair of source Layer-2 ID and destination Layer-2 ID) when one of the following conditions is met:

[0278] - if maxHARQRetxThreshold is configured by RRC (e.g., the initial step of HARQ-based RLM, e.g., when establishing a PC5-RRC connection or PC5-S unicast link); and / or

[0279] - if parameters related to the establishment of a PC5-RRC connection or PC5-S unicast link are indicated by upper layers; and / or

[0280] - if the first new transmission is triggered by this sidelink HARQ entity for a PC5-RRC connection (or a PC5-S unicast link established by a PC5-S entity, a destination or a pair of source layer-2 ID and destination layer-2 ID); and / or

[0281] - If N acknowledgments are received on the PSFCH, either consecutively or intermittently (where N may be one or greater):

[0282] - N acknowledgments may correspond to positive acknowledgments successfully received only on the PSFCH; and / or

[0283] - N ACKs may correspond to negative ACKs successfully received only on the PSFCH; and / or

[0284] - the N acknowledgments may correspond to both positive and negative acknowledgments successfully received on the PSFCH; and / or

[0285] -The N acknowledgments may not include unsuccessful reception of any acknowledgment on the PSFCH (e.g., no HARQ feedback transmission of an acknowledgment from the peer UE (e.g., because the peer UE did not successfully receive the corresponding PSCCH and / or PSSCH) or no HARQ feedback transmission from the peer UE (e.g., because the UE did not successfully receive the corresponding PSFCH).

[0286] In step 1404, the sidelink HARQ entity in the TX UE may increment MAX_RLM_ReTX_COUNT for each PC5-RRC connection that has been established by RRC (or for each PC5-S unicast link established by the PC5-S entity, each destination, or each pair of source layer-2 ID and destination layer-2 ID) when one of the following conditions is met:

[0287] - if no acknowledgement is received on the PSFCH for the transmission of any MAC PDU; and / or

[0288] - Option 1: The acknowledgement may correspond to a positive acknowledgement of successful reception on the PSFCH only;

[0289] - Option 2: The acknowledgment may correspond to a negative acknowledgment of successful reception on the PSFCH only;

[0290] - Option 3: The acknowledgment may correspond to a positive acknowledgment or a negative acknowledgment of successful reception on the PSFCH only;

[0291] - If a negative acknowledgement has been received on the PSFCH for the transmission of any MAC PDU.

[0292] For example, in step 1404a, the TX UE may send a MAC PDU to the RX UE. In step 1404b, the TX UE may receive a NACK from the RX UE. In step 1404c, based on receiving the NACK associated with the MAC PDU, the TX UE may increment the MAX_RLM_ReTX_Count.

[0293] For example, in step 1404d, the TX UE may send a MAC PDU to the RX UE.In step 1404e, based on not receiving any acknowledgement (ACK or NACK) related to the MAC PDU, the TX UE may increment the MAX_RLM_ReTX_Count.

[0294] For example, in step 1404f, the TX UE may send a MAC PDU to the RX UE. In step 1404g, the TX UE may receive an ACK from the RX UE. In step 1404h, the TX UE may send a MAC PDU to the RX UE. In step 1404i, the TX UE may receive an ACK from the RX UE. In step 1404j, based on the TX UE receiving two consecutive ACKs from the RX UE (e.g., the N value may be configured as 2), the TX UE may reset MAX_RLM_ReTX_Count.

[0295] For example, in step 1404k, the TX UE may transmit a MAC PDU to the RX UE. In step 1404l, based on not receiving any acknowledgment (ACK or NACK) associated with the MAC PDU, the TX UE may increment MAX_RLM_ReTX_Count. In step 1404m, the TX UE may transmit a MAC PDU to the RX UE. In step 1404n, based on not receiving any acknowledgment associated with the MAC PDU, the TX UE may increment MAX_RLM_ReTX_Count. In step 1404o, the TX UE may transmit a MAC PDU to the RX UE. In step 1404p, based on not receiving any acknowledgment associated with the MAC PDU, the TX UE may increment MAX_RLM_ReTX_Count.

[0296] In step 1405, if MAX_RLM_ReTX_COUNT reaches maxHARQRetxThreshold, the MAC entity in the TX UE may indicate to the RRC that the maximum HARQ retransmissions have been reached for each PC5-RRC connection established by the RRC (or for each PC5-S unicast link established by the PC5-S entity, each destination, or each pair of source layer-2ID and destination layer-2ID).

[0297] In step 1406, upon receiving the indication from the MAC entity, the TX UE RRC may declare a sidelink radio link failure on the corresponding PC5-RRC connection (or the corresponding pair or the corresponding destination) and indicate the sidelink radio link failure to the network.

[0298] According to some embodiments of the present disclosure, UL transmission and SL transmission may be performed for different RATs or the same RAT.

[0299] The present disclosure may also be applied to radio link failures of different uplink transmissions to different base stations, e.g. configured for dual connectivity or carrier aggregation in uplink. In this case, Figure 14 The TX UE in can be replaced by the same or different base station.

[0300] Hereinafter, a method for indicating a sidelink radio link failure in a wireless communication system according to some embodiments of the present disclosure will be described. The method may be performed by a wireless device (eg, a UE).

[0301] According to some embodiments of the present disclosure, the UE may perform sidelink HARQ operations.

[0302] For example, the sidelink HARQ entity of the UE may perform the following operations.

[0303] The MAC entity includes at most one sidelink HARQ entity for transmission on the SL-SCH, which maintains multiple parallel sidelink processes.

[0304] The maximum number of transmit sidelink processes associated with a sidelink HARQ entity is [TBD]. [A sidelink process may be configured for transmission of multiple MAC PDUs. For transmission of multiple MAC PDUs, the maximum number of transmit sidelink processes associated with a sidelink HARQ entity is [TBD].]

[0305] The delivered sidelink grant and its associated HARQ information are associated with a sidelink process. Each sidelink process supports one TB.

[0306] For each sidelink grant, the sidelink HARQ entity shall:

[0307] 1> Associate sidelink processes with this authorization, and for each associated sidelink process:

[0308] 2> If the MAC entity determines that the sidelink is granted for the initial transmission, and if no MAC PDU is obtained:

[0309] For configured grant types 1 and 2, whether the sidelink grant is for initial transmission or retransmission is up to the UE implementation.

[0310] 3> Obtain the MAC PDU to be sent from the multiplexing and assembly entity (if any);

[0311] 3> If the MAC PDU to be sent has been obtained:

[0312] 4> Deliver the TB's QoS information and HARQ information, MAC PDU, and sidelink grant to the associated sidelink process;

[0313] 4>Instruct the associated side link process to trigger a new transmission;

[0314] 3> Otherwise:

[0315] 4>Flush the HARQ buffer of the associated sidelink process.

[0316] 2> Otherwise (i.e., retransmit):

[0317] 3> whether a positive acknowledgement of the transmission of the MAC PDU has been received; or

[0318] 3> If only negative acknowledgment is configured and the negative acknowledgment is for the latest (re)transmission of the MAC PDU:.

[0319] 4> Clear side link authorization;

[0320] 4>Flush the HARQ buffer of the associated sidelink process;

[0321] 3> Otherwise:

[0322] 4> Deliver the MAC PDU's QoS information and HARQ information and sidelink grant to the associated sidelink process;

[0323] 4>Instruct the associated sidelink process to trigger retransmission.

[0324] The sidelink HARQ entity maintains the N value, maxHARQRetxThreshold, and MAX_RLM_ReTX_COUNT for only unicast in the sidelink for each PC5-RRC connection that has been established by RRC (or for each PC5-S unicast link, destination, or pair of source layer-2 ID and destination layer-2 ID established by the PC5-S entity). The N value and maxHARQRetxThreshold are configured by RRC for a PC5-RRC connection (or a PC5-S unicast link, destination, or pair of source layer-2 ID and destination layer-2 ID established by the PC5-S entity).

[0325] The side link HARQ entity corresponds to both the receiving side link HARQ entity and the transmitting side link HARQ entity, or the receiving side link HARQ entity or the transmitting side link HARQ entity.

[0326] Alternatively, maxHARQRetxThreshold is configured with the value of maxHARQRetxThreshold configured for the logical channel with the highest priority belonging to the PC5-RRC connection or with the lowest value, average value or highest value of all maxHARQRetxThreshold values configured for all logical channels belonging to the PC5-RRC connection (or a PC5-S unicast link established by a PC5-S entity, a destination or a pair of source layer-2ID and destination layer-2ID).

[0327] Alternatively, the N value is configured with the value of the N value configured for the logical channel with the highest priority belonging to the PC5-RRC connection or with the lowest value, average value or highest value of all N values configured for all logical channels belonging to the PC5-RRC connection (or a PC5-S unicast link established by a PC5-S entity, a destination or a pair of source layer-2ID and destination layer-2ID).

[0328] For each PC5-RRC connection established by RRC (or for each PC5-S unicast link established by the PC5-S entity, each destination, or each pair of source layer-2 ID and destination layer-2 ID), the sidelink HARQ entity shall:

[0329] 1> if maxHARQRetxThreshold is configured by RRC (e.g., the initial step of HARQ-based RLM, e.g., when establishing a PC5-RRC connection or PC5-S unicast link); or

[0330] 1> If the parameters related to the establishment of a PC5-RRC connection or PC5-S unicast link are indicated by upper layers; or

[0331] 1> if the first new transmission is triggered by this sidelink HARQ entity for a PC5-RRC connection (or a PC5-S unicast link established by a PC5-S entity, a destination or a pair of source layer-2 ID and destination layer-2 ID); or

[0332] 1> if N acknowledgments are received on the PSFCH, either continuously or intermittently (where N may be one or greater); or

[0333] Option 1: N acknowledgments correspond to positive acknowledgments successfully received only on the PSFCH;

[0334] Option 2: N ACKs correspond to negative ACKs successfully received on PSFCH only;

[0335] Option 3: N acknowledgments correspond to both positive and negative acknowledgments successfully received on the PSFCH;

[0336] The N acknowledgments may not include unsuccessful reception of any acknowledgment on the PSFCH (i.e., no HARQ feedback transmission of an acknowledgment from a peer UE (e.g., because the peer UE did not successfully receive the corresponding PSCCH and / or PSSCH) or no HARQ feedback transmission from a peer UE (e.g., because the UE did not successfully receive the corresponding PSFCH). N may be one or greater.

[0337] 2> Set MAX_RLM_ReTX_COUNT to zero.

[0338] 1> If no acknowledgement is received on the PSFCH for the transmission of any MAC PDU; or

[0339] Option 1: The acknowledgment corresponds to a positive acknowledgment of successful reception on the PSFCH only;

[0340] Option 2: The acknowledgment corresponds to a negative acknowledgment of successful reception on the PSFCH only;

[0341] Option 3: Acknowledgement corresponds to positive or negative acknowledgement of successful reception on PSFCH only;

[0342] 1> If a negative acknowledgement of the transmission of any MAC PDU is received on the PSFCH:

[0343] 2>Increment MAX_RLM_ReTX_Count.

[0344] 1>If MAX_RLM_ReTX_COUNT=maxHARQRetxThreshold:

[0345] - Indicates to RRC that the maximum HARQ retransmissions has been reached.

[0346] Upon receiving the indication from the MAC entity, the UE RRC declares a sidelink radio link failure on the corresponding PC5-RRC connection (or the corresponding pair or the corresponding destination).

[0347] Hereinafter, a method for indicating a sidelink radio link failure in a wireless communication system according to some embodiments of the present disclosure will be described. The method may be performed by a wireless device (eg, a UE).

[0348] According to some embodiments of the present disclosure, the UE may perform sidelink HARQ operations.

[0349] For example, the sidelink HARQ entity of the UE may perform the following operations.

[0350] The MAC entity includes at most one sidelink HARQ entity for transmission on the SL-SCH, which maintains multiple parallel sidelink processes.

[0351] There is at most one sidelink HARQ entity at the MAC entity for reception of SL-SCH, which maintains multiple parallel sidelink processes.

[0352] Each sidelink process is associated with an SCI that the MAC entity is interested in. This interest is determined by the destination layer-1 ID and source layer-1 ID of the SCI. The sidelink HARQ entity directs the HARQ information and associated TBs received on the SL-SCH to the corresponding sidelink process.

[0353] The number of receive sidelink processes associated with a sidelink HARQ entity is defined as [TBD].

[0354] For each PSSCH duration, the sidelink HARQ entity shall:

[0355] 1> For each SCI valid for this PSSCH duration:

[0356] 2> If the PSSCH duration corresponds to a new transmission opportunity according to the SCI:

[0357] 3> Assign the TB and associated HARQ information received from the physical layer to an unoccupied sidelink process, associate the sidelink process with the SCI, and consider the transmission to be a new transmission.

[0358] 1>For each side link process:

[0359] 2> If the PSSCH duration corresponds to a retransmission opportunity according to the sidelink process with its associated SCI:

[0360] 3> The TB and associated HARQ information received from the physical layer are assigned to the sidelink process and the transmission is considered to be a retransmission.

[0361] The sidelink HARQ entity maintains the N value, maxHARQRetxThreshold, and MAX_RLM_ReTX_COUNT for only unicast in the sidelink for each PC5-RRC connection that has been established by RRC (or for each PC5-S unicast link, destination, or pair of source layer-2 ID and destination layer-2 ID established by the PC5-S entity). The N value and maxHARQRetxThreshold are configured by RRC for a PC5-RRC connection (or a PC5-S unicast link, destination, or pair of source layer-2 ID and destination layer-2 ID established by the PC5-S entity).

[0362] The side link HARQ entity corresponds to both the receiving side link HARQ entity and the transmitting side link HARQ entity, or the receiving side link HARQ entity or the transmitting side link HARQ entity.

[0363] Alternatively, maxHARQRetxThreshold is configured with the value of maxHARQRetxThreshold configured for the logical channel with the highest priority belonging to the PC5-RRC connection or with the lowest value, average value or highest value of all maxHARQRetxThreshold values configured for all logical channels belonging to the PC5-RRC connection (or a PC5-S unicast link established by a PC5-S entity, a destination or a pair of source layer-2ID and destination layer-2ID).

[0364] Alternatively, the N value is configured with the value of the N value configured for the logical channel with the highest priority belonging to the PC5-RRC connection or with the lowest value, average value or highest value of all N values configured for all logical channels belonging to the PC5-RRC connection (or a PC5-S unicast link established by a PC5-S entity, a destination or a pair of source layer-2ID and destination layer-2ID).

[0365] For each PC5-RRC connection established by RRC (or for each PC5-S unicast link established by the PC5-S entity, each destination, or each pair of source layer-2 ID and destination layer-2 ID), the sidelink HARQ entity shall:

[0366] 1> if maxHARQRetxThreshold is configured by RRC (e.g., the initial step of HARQ-based RLM, e.g., when establishing a PC5-RRC connection or PC5-S unicast link); or

[0367] 1> If the parameters related to the establishment of a PC5-RRC connection or PC5-S unicast link are indicated by upper layers; or

[0368] 1> if an SCI transmission scheduling the first (re)transmission is received for a PC5-RRC connection (or a PC5-S unicast link established by a PC5-S entity, a destination or a pair of source Layer-2 ID and destination Layer-2 ID); or

[0369] 1> if the first (re)transmission is received by the sidelink HARQ entity for a PC5-RRC connection (or a PC5-S unicast link established by a PC5-S entity, a destination or a pair of source layer-2 ID and destination layer-2 ID); or

[0370] 1> if N acknowledgments are sent continuously or intermittently on the PSFCH (where N may be one or greater); or

[0371] Option 1: N acknowledgments correspond to positive acknowledgments successfully sent only on the PSFCH;

[0372] Option 2: N acknowledgments correspond to negative acknowledgments that were successfully sent on the PSFCH only;

[0373] Option 3: N acknowledgments correspond to both positive and negative acknowledgments successfully sent on the PSFCH;

[0374] The N acknowledgments may not include unsuccessful transmission of any acknowledgment on the PSFCH (ie, HARQ feedback transmission without an acknowledgment from the UE (eg, because the UE did not successfully receive the corresponding PSCCH and / or PSSCH).

[0375] Here, N can be one or greater.

[0376] 2> Set MAX_RLM_ReTX_COUNT to zero.

[0377] 1> if a sidelink transmission on PSCCH and / or PSSCH previously indicated or scheduled by any SCI has been successfully received; or

[0378] 1> if no negative acknowledgement of the transmission of any MAC PDU is sent on the PSFCH; or

[0379] 1> If no acknowledgement of the transmission of any MAC PDU is sent on the PSFCH:

[0380] 2>Increment MAX_RLM_ReTX_Count.

[0381] 1>If MAX_RLM_ReTX_COUNT=maxHARQRetxThreshold:

[0382] - Indicates to RRC that the maximum HARQ retransmissions has been reached.

[0383] Upon receiving the indication from the MAC entity, the UE RRC declares a sidelink radio link failure on the corresponding PC5-RRC connection (or the corresponding pair or the corresponding destination).

[0384] Hereinafter, a method for indicating a sidelink radio link failure in a wireless communication system according to some embodiments of the present disclosure will be described. The method may be performed by a wireless device (eg, a UE).

[0385] According to some embodiments of the present disclosure, the UE may perform HARQ-based sidelink RLF detection.

[0386] The HARQ-based sidelink RLF detection procedure is used to detect sidelink RLF based on the number of consecutive DTXs on PSFCH reception opportunities for the PC5-RRC connection.

[0387] The RRC configures the following parameters to control HARQ-based sidelink RLF detection:

[0388] -sl-maxNumConsecutiveDTX.

[0389] The following UE variables are used for HARQ-based sidelink RLF detection.

[0390] - numConsecutiveDTX, which is maintained for each PC5-RRC connection.

[0391] When establishing a PC5-RRC connection or (re)configuring sl-maxNumConsecutiveDTX, the sidelink HARQ entity shall (re)initialize numConsecutiveDTX to zero for each PC5-RRC connection (if any) that has been established by upper layers.

[0392] The sidelink HARQ entity shall, for each PSFCH reception opportunity associated with a PSSCH transmission:

[0393] 1> If there is no PSFCH reception at the PSFCH reception opportunity:

[0394] 2>Increment numConsecutiveDTX by 1;

[0395] 2>If numConsecutiveDTX reaches sl-maxNumConsecutiveDTX:

[0396] 3> Indicate HARQ-based sidelink RLF detection to RRC.

[0397] 1> Otherwise:

[0398] 2>Reinitialize numConsecutiveDTX to zero.

[0399] Hereinafter, a device for indicating a side link radio link failure in a wireless communication system according to some embodiments of the present disclosure will be described. In this document, the device may be Figure 2 、 Figure 3 and Figure 5 A wireless device (100 or 200) in.

[0400] For example, the first wireless device may perform the above method. Detailed descriptions that overlap with the above content may be simplified or omitted.

[0401] Reference Figure 5 , the first wireless device 100 may include a processor 102 , a memory 104 , and a transceiver 106 .

[0402] According to some embodiments of the present disclosure, the processor 102 may be configured to be operably coupled with the memory 104 and the transceiver 106 .

[0403] The processor 102 may be configured to configure a maximum number of counters for a PC5-radio resource control (RRC) connection with a second wireless device. The processor 102 may be configured to initialize the counter to zero upon 1) establishing a PC5-RRC connection with the second wireless device or 2) configuring or reconfiguring the maximum number of counters. The processor 102 may be configured to control the transceiver 106 to perform transmission of a medium access control (MAC) protocol data unit (PDU) to the second wireless device based on the established PC5-RRC connection. The processor 102 may be configured to increment the counter based on the lack of receiving any acknowledgment for the transmission of the MAC PDU. The processor 102 may be configured to indicate a sidelink (SL) radio link failure (RLF) for the PC5-RRC connection based on the counter reaching the maximum number of counters.

[0404] According to some embodiments of the present disclosure, the processor 102 may be configured to notify the network of the SL RLF.

[0405] According to some embodiments of the present disclosure, the processor 102 may be configured to control a SL Hybrid Automatic Repeat Request (HARQ) entity of the first wireless apparatus to notify an RRC entity of the first wireless apparatus of the SL RLF.

[0406] According to some embodiments of the present disclosure, the processor 102 may be configured to configure a counter for each of a plurality of PC5-RRC connections with other wireless devices.

[0407] According to some embodiments of the present disclosure, the processor 102 may be configured to configure another counter for another PC5-RRC connection with a third wireless device.

[0408] For example, the processor 102 may be configured to initialize another counter to zero when 1) establishing another PC5-RRC connection with a third wireless device or 2) configuring or reconfiguring a maximum number of another counter for another PC5-RRC connection with a third wireless device.

[0409] For example, the maximum number of another counter for another PC5-RRC connection with the third wireless device may be the same as the maximum number of counters for the PC5-RRC connection with the second wireless device.

[0410] According to some embodiments of the present disclosure, the processor 102 may be configured to monitor each physical sidelink feedback channel (PSFCH) reception opportunity associated with the transmission of a MAC PDU. Based on the absence of PSFCH reception on the PSFCH reception opportunity, the processor 102 may be configured to increment a counter.

[0411] According to some embodiments of the present disclosure, the processor 102 may be configured to reinitialize the counter to zero based on receipt of any acknowledgement of transmission of the MAC PDU.

[0412] For example, the processor 102 may be configured to monitor each PSFCH reception opportunity associated with the transmission of the MAC PDU.Based on the presence of PSFCH reception at the PSFCH reception opportunity, the processor 102 may be configured to reinitialize the counter to zero.

[0413] According to some embodiments of the present disclosure, transmission of a MAC PDU may include a PSSCH transmission for a source Layer-2 ID of a first wireless device and a destination Layer-2-ID of a second wireless device corresponding to a pair of PC5-RRC connections.

[0414] According to some embodiments of the present disclosure, the processor 102 may be configured to communicate with at least one of a user device other than the first wireless apparatus, a network, or an autonomous vehicle.

[0415] Hereinafter, a processor of a first wireless device for indicating a sidelink radio link failure in a wireless communication system according to some embodiments of the present disclosure will be described.

[0416] The processor may be configured to control a first wireless device to configure a maximum number of counters for a PC5-radio resource control (RRC) connection with a second wireless device. The processor may be configured to control the first wireless device to initialize a counter to zero when 1) establishing a PC5-RRC connection with the second wireless device or 2) configuring or reconfiguring the maximum number of counters. The processor may be configured to control the first wireless device to perform transmission of a medium access control (MAC) protocol data unit (PDU) to the second wireless device based on the established PC5-RRC connection. The processor may be configured to control the first wireless device to increment a counter based on a failure to receive any acknowledgment for the transmission of the MAC PDU. The processor may be configured to control the first wireless device to indicate a sidelink (SL) radio link failure (RLF) for the PC5-RRC connection based on the counter reaching the maximum number of counters.

[0417] According to some embodiments of the present disclosure, the processor may be configured to control the first wireless apparatus to notify the network of the SL RLF.

[0418] According to some embodiments of the present disclosure, the processor may be configured to control the first wireless apparatus to control an SL Hybrid Automatic Repeat Request (HARQ) entity of the first wireless apparatus to notify an RRC entity of the first wireless apparatus of the SLRLF.

[0419] According to some embodiments of the present disclosure, the processor may be configured to control the first wireless device to configure a counter for each of a plurality of PC5-RRC connections with other wireless devices.

[0420] According to some embodiments of the present disclosure, the processor may be configured to control the first wireless apparatus to configure another counter for another PC5-RRC connection with the third wireless apparatus.

[0421] For example, the processor may be configured to control the first wireless apparatus to initialize another counter to zero when 1) establishing another PC5-RRC connection with a third wireless apparatus or 2) configuring or reconfiguring a maximum number of another counter for another PC5-RRC connection with a third wireless apparatus.

[0422] For example, the maximum number of another counter for another PC5-RRC connection with the third wireless device may be the same as the maximum number of counters for the PC5-RRC connection with the second wireless device.

[0423] According to some embodiments of the present disclosure, the processor may be configured to control the first wireless apparatus to monitor each physical sidelink feedback channel (PSFCH) reception opportunity associated with the transmission of a MAC PDU. Based on the absence of PSFCH reception at the PSFCH reception opportunity, the processor may be configured to control the first wireless apparatus to increment a counter.

[0424] According to some embodiments of the present disclosure, the processor may be configured to control the first wireless apparatus to reinitialize the counter to zero based on receipt of any acknowledgement of transmission of the MAC PDU.

[0425] For example, the processor may be configured to control the first wireless apparatus to monitor each PSFCH reception opportunity associated with transmission of a MAC PDU.Based on the presence of PSFCH reception at the PSFCH reception opportunity, the processor may be configured to control the first wireless apparatus to reinitialize the counter to zero.

[0426] According to some embodiments of the present disclosure, transmission of a MAC PDU may include a PSSCH transmission for a source Layer-2 ID of a first wireless device and a destination Layer-2-ID of a second wireless device corresponding to a pair of PC5-RRC connections.

[0427] According to some embodiments of the present disclosure, the processor may be configured to control the first wireless apparatus to communicate with at least one of a user device other than the first wireless apparatus, a network, or an autonomous vehicle.

[0428]

[0014] Hereinafter, a non-transitory computer-readable medium having stored thereon a plurality of instructions for indicating a sidelink radio link failure in a wireless communication system will be described according to some embodiments of the present disclosure.

[0429] According to some embodiments of the present disclosure, the technical features of the present disclosure may be implemented directly in hardware, in software executed by a processor, or in a combination of the two. For example, a method performed by a wireless device in wireless communication may be implemented in hardware, software, firmware, or any combination thereof. For example, the software may reside in RAM memory, flash memory, ROM memory, EPROM memory, EEPROM memory, registers, a hard disk, a removable disk, a CD-ROM, or any other storage medium.

[0430] Some examples of storage media are coupled to a processor so that the processor can read information from the storage media. In an alternative embodiment, the storage medium can be integrated into the processor. The processor and storage medium can reside in an ASIC. For other examples, the processor and storage medium can reside as discrete components.

[0431] Computer-readable media may include tangible and non-transitory computer-readable storage media.

[0432] For example, non-transitory computer-readable media may include random access memory (RAM) such as synchronous dynamic random access memory (SDRAM), read-only memory (ROM), non-volatile random access memory (NVRAM), electrically erasable programmable read-only memory (EEPROM), FLASH memory, magnetic or optical data storage media, or any other medium that can be used to store instructions or data structures. Non-transitory computer-readable media may also include combinations of the foregoing.

[0433] Furthermore, the methods described herein may be implemented at least in part by a computer-readable communication medium that carries or communicates code in the form of instructions or data structures and that can be accessed, read, and / or executed by a computer.

[0434] According to some embodiments of the present disclosure, a plurality of instructions are stored on a non-transitory computer-readable medium, and the plurality of stored instructions may be executed by a processor of a first wireless device.

[0435] The stored instructions may cause a first wireless device to configure a maximum number of counters for a PC5-Radio Resource Control (RRC) connection with a second wireless device. The stored instructions may cause the first wireless device to initialize a counter to zero when 1) establishing a PC5-RRC connection with the second wireless device or 2) configuring or reconfiguring the maximum number of counters. The stored instructions may cause the first wireless device to perform a transmission of a Medium Access Control (MAC) Protocol Data Unit (PDU) to the second wireless device based on the established PC5-RRC connection. The stored instructions may cause the first wireless device to increment a counter based on a failure to receive any acknowledgment for the transmission of the MAC PDU. The stored instructions may cause the first wireless device to indicate a sidelink (SL) radio link failure (RLF) for the PC5-RRC connection based on the counter reaching the maximum number of counters.

[0436] According to some embodiments of the present disclosure, the stored plurality of instructions may enable the first wireless device to notify the network of the SL RLF.

[0437] According to some embodiments of the present disclosure, the stored plurality of instructions may enable the first wireless apparatus to control an SL hybrid automatic repeat request (HARQ) entity of the first wireless apparatus to notify an RRC entity of the first wireless apparatus of the SLRLF.

[0438] According to some embodiments of the present disclosure, the stored plurality of instructions may enable the first wireless device to configure a counter for each of a plurality of PC5-RRC connections with other wireless devices.

[0439] According to some embodiments of the present disclosure, the stored plurality of instructions may cause the first wireless apparatus to configure another counter for another PC5-RRC connection with a third wireless apparatus.

[0440] For example, the stored instructions may cause the first wireless apparatus to initialize another counter to zero when 1) establishing another PC5-RRC connection with a third wireless apparatus or 2) configuring or reconfiguring a maximum number of another counter for another PC5-RRC connection with a third wireless apparatus.

[0441] For example, the maximum number of another counter for another PC5-RRC connection with the third wireless device may be the same as the maximum number of counters for the PC5-RRC connection with the second wireless device.

[0442] According to some embodiments of the present disclosure, the plurality of stored instructions may cause a first wireless apparatus to monitor each physical sidelink feedback channel (PSFCH) reception opportunity associated with the transmission of a MAC PDU. Based on the absence of PSFCH reception at the PSFCH reception opportunity, the plurality of stored instructions may cause the first wireless apparatus to increment a counter.

[0443] According to some embodiments of the present disclosure, the stored plurality of instructions may cause the first wireless apparatus to reinitialize the counter to zero based on receipt of any acknowledgment of the transmission of the MAC PDU.

[0444] For example, the stored instructions may cause the first wireless apparatus to monitor each PSFCH reception opportunity associated with the transmission of a MAC PDU. Based on the presence of PSFCH reception at the PSFCH reception opportunity, the stored instructions may cause the first wireless apparatus to reinitialize the counter to zero.

[0445] According to some embodiments of the present disclosure, transmission of a MAC PDU may include a PSSCH transmission for a source Layer-2 ID of a first wireless device and a destination Layer-2-ID of a second wireless device corresponding to a pair of PC5-RRC connections.

[0446] According to some embodiments of the present disclosure, the stored plurality of instructions may enable the first wireless apparatus to communicate with at least one of a user device other than the first wireless apparatus, a network, or an autonomous vehicle.

[0447] Hereinafter, a method for indicating a sidelink radio link failure, performed by a base station (BS) in a wireless communication system according to some embodiments of the present disclosure, will be described.

[0448] The base station may transmit, to a first wireless device, a configuration of a maximum number of counters for a PC5-radio resource control (RRC) connection with a second wireless device. The base station may receive, from the first wireless device, a sidelink (SL) radio link failure (RLF) for the PC5-RRC connection based on the counter reaching the maximum number of counters.

[0449] Hereinafter, a base station (BS) for indicating a sidelink radio link failure in a wireless communication system according to some embodiments of the present disclosure will be described.

[0450] The BS may include a transceiver, a memory, and a processor operatively coupled to the transceiver and the memory.

[0451] The processor may be configured to control the transceiver to transmit, to the first wireless apparatus, a configuration of a maximum number of counters for a PC5-radio resource control (RRC) connection with the second wireless apparatus. The processor may be configured to control the transceiver to receive, from the first wireless apparatus, a sidelink (SL) radio link failure (RLF) for the PC5-RRC connection based on the counter reaching the maximum number of counters.

[0452] The present disclosure can have various advantageous effects.

[0453] According to some embodiments of the present disclosure, a wireless device may efficiently indicate a sidelink (SL) radio link failure (RLF) in a wireless communication system.

[0454] For example, a wireless device that performs radio link management by using HARQ feedback can appropriately detect radio link failure by considering HARQ feedback transmission from another wireless device.

[0455] For example, when a UE establishes a sidelink connection with a peer UE, the UE can appropriately detect radio link failure by considering HARQ feedback transmission from the other UE.

[0456] For example, the wireless communication system may appropriately provide radio link management for a sidelink connection for a UE performing HARQ transmission.

[0457] The advantageous effects that can be obtained by the specific embodiments of the present disclosure are not limited to the advantageous effects listed above. For example, there may be various technical effects that can be understood and / or derived from the present disclosure by a person of ordinary skill in the relevant art. Therefore, the specific effects of the present disclosure are not limited to those explicitly described herein, but may include various effects that can be understood or derived from the technical features of the present disclosure.

[0458] The claims in this disclosure may be combined in various ways. For example, the technical features in the method claims of this disclosure may be combined to be implemented or performed in a device, and the technical features in the device claims may be combined to be implemented or performed in a method. Furthermore, the technical features in the method claims and the device claims may be combined to be implemented or performed in a device. Furthermore, the technical features in the method claims and the device claims may be combined to be implemented or performed in a method. Other implementations are within the scope of the appended claims.

Claims

1. A method performed by a wireless device, the method comprising the steps of: Establish one or more PC5-RRC connections, Each PC5-RRC connection is a connection for a pair of source identifier and target identifier; receiving a message from a network, the message including information related to a maximum transmission quantity; Configure the transmission count counter maintained for each PC5-RRC connection; Initializing the transmission number counter maintained for the specific PC5-RRC connection to zero based on (i) the maximum transmission number being configured or reconfigured or (ii) a specific PC5-RRC connection being established; Performing a transmission for a pair of source and destination identifiers corresponding to the specific PC5-RRC connection; Based on not receiving an acknowledgment for the transmission, incrementing by one the transmission number counter maintained for the particular PC5-RRC connection; and Based on the transmission number counter maintained for the specific PC5-RRC connection reaching the maximum transmission number, a hybrid automatic repeat request entity of the wireless device indicates a sidelink radio link failure for the PC5-RRC connection to a radio resource control layer of the wireless device.

2. The method according to claim 1, wherein The method further comprises the following steps: The network is notified of the sidelink radio link failure for the PC5-RRC connection.

3. The method according to claim 1, wherein The method further comprises the following steps: A new transmission number counter maintained for a new PC5-RRC connection corresponding to a new pair of source and target identifiers is configured.

4. The method according to claim 3, wherein: The method further comprises the following steps: Based on (i) the maximum transmission number being configured or reconfigured or (ii) the new PC5-RRC connection being established, the new transmission number counter maintained for the new PC5-RRC connection is initialized to zero.

5. The method according to claim 4, in, The maximum number of the new transmission number counter maintained for the new PC5-RRC connection is the same as the maximum number of the transmission number counter maintained for the specific PC5-RRC connection.

6. The method according to claim 1, wherein The step of incrementing the transmission number counter maintained for the specific PC5-RRC connection by one further comprises: monitoring each physical sidelink feedback channel reception opportunity associated with the transmission; and Based on the absence of physical sidelink feedback channel reception at the physical sidelink feedback channel reception opportunity, the transmission quantity counter is incremented.

7. The method according to claim 1, wherein The method further comprises the following steps: The transmission number counter is reinitialized to zero based on receipt of an acknowledgment of the transmission.

8. The method according to claim 7, wherein: The step of reinitializing the transmission quantity counter to zero further comprises: monitoring each physical sidelink feedback channel reception opportunity associated with the transmission; and Based on the presence of physical side link feedback channel reception at the physical side link feedback channel reception opportunity, the transmission quantity counter is reinitialized to zero.

9. The method according to claim 1, wherein The transmission includes a physical shared channel transmission corresponding to the specific PC5-RRC connection.

10. The method according to claim 1, wherein The wireless device communicates with at least one of a user device other than the wireless device, a network, or an autonomous vehicle.

11. A wireless device, comprising: transceiver; Memory; as well as at least one processor operatively coupled to the transceiver and the memory and configured to: Establish one or more PC5-RRC connections, Each PC5-RRC connection is a connection for a pair of source identifier and target identifier; receiving a message from a network, the message including information related to a maximum transmission quantity; Configure the transmission count counter maintained for each PC5-RRC connection; Initializing the transmission number counter maintained for the specific PC5-RRC connection to zero based on (i) the maximum transmission number being configured or reconfigured or (ii) a specific PC5-RRC connection being established; Performing a transmission for a pair of source and destination identifiers corresponding to the specific PC5-RRC connection; Based on not receiving an acknowledgment for the transmission, incrementing by one the transmission number counter maintained for the particular PC5-RRC connection; and Based on the transmission number counter maintained for the specific PC5-RRC connection reaching the maximum transmission number, a hybrid automatic repeat request entity of the wireless device indicates a sidelink radio link failure for the PC5-RRC connection to a radio resource control layer of the wireless device.

12. A non-transitory computer-readable medium having stored thereon a plurality of instructions that, when executed by a processor of a wireless device, cause the wireless device to: Establish one or more PC5-RRC connections, in, Each PC5-RRC connection is a connection for a pair of source and target identities; receiving a message from a network, the message including information related to a maximum transmission quantity; Configure the transmission count counter maintained for each PC5-RRC connection; Initializing the transmission number counter maintained for the specific PC5-RRC connection to zero based on (i) the maximum transmission number being configured or reconfigured or (ii) a specific PC5-RRC connection being established; Performing a transmission for a pair of source and destination identifiers corresponding to the specific PC5-RRC connection; Based on not receiving an acknowledgment for the transmission, incrementing by one the transmission number counter maintained for the specific PC5-RRC connection; and Based on the transmission number counter maintained for the specific PC5-RRC connection reaching the maximum transmission number, a hybrid automatic repeat request entity of the wireless device indicates a sidelink radio link failure for the PC5-RRC connection to a radio resource control layer of the wireless device.

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