Method and apparatus for autonomous serving cell handover in wireless communication system

Abstract

A method and apparatus for autonomous serving cell handover in a wireless communication system are provided. A wireless device may perform operations including: configuring a connection with a serving cell; receiving a configuration for one or more candidate serving cells; acquiring an uplink transmission timing for at least one candidate serving cell among the one or more candidate serving cells; detecting a failure related to the serving cell; selecting a specific candidate serving cell among the at least one candidate serving cell from which the uplink transmission timing has been acquired; and performing a serving cell handover from the serving cell to the specific candidate serving cell based on the configuration for the specific candidate serving cell.

Description

Technical Field

[0001] The present disclosure relates to a method and an apparatus for autonomous serving cell handover in a wireless communication system. Background Art

[0002] The 3rd Generation Partnership Project (3GPP) Long Term Evolution (LTE) is a technology that allows high-speed packet communication. Many solutions have been proposed for LTE goals, including those aimed at reducing user and vendor costs, improving service quality, and expanding and improving coverage and system capacity. As an upper layer requirement, 3GPP LTE needs to reduce cost per bit, increase service availability, flexibly use frequency bands, have a simple structure, open interfaces, and appropriate power consumption of terminals.

[0003] The International Telecommunication Union (ITU) and 3GPP have started to work on developing requirements and specifications for a New Radio (NR) system. 3GPP must identify and develop the technical components required for successful standardization of a new RAT that will meet both the urgent market needs in a timely manner and the longer-term requirements proposed by the International Mobile Telecommunications (IMT)-2020 process of the ITU Radiocommunication Sector (ITU-R). In addition, NR should be able to use any spectrum band in the range of at least up to 100 GHz that can be used for wireless communication even in the more distant future.

[0004] The goal of NR is a single technical framework that can address all usage scenarios, requirements, and deployment scenarios, including enhanced mobile broadband (eMBB), massive machine type communication (mMTC), ultra-reliable and low latency communication (URLLC), etc. NR should be inherently forward compatible. Summary of the Invention

[0005] Technical Problem

[0006] When a beam failure is detected on the PCell, the UE performs a random access procedure for beam failure recovery. While performing the RA procedure, uplink transmission and downlink reception are suspended. When a radio link failure is detected, the UE performs an RRC reestablishment procedure, and it also requires the UE to perform an RA procedure.

[0007] If the UE has a complete configuration of a cell (i.e., a candidate serving cell that has been prepared for potential connection) and knows the exact uplink transmission timing, the candidate serving cell can be used by the UE for communication when communication with the serving cell is unavailable for various reasons.

[0008] For example, when the serving cell becomes unavailable due to beam failure, RLF, or other failure reasons, if the UE performs autonomous cell handover to one of the candidate cells with known UL timing, the UE can continue to perform uplink transmission and downlink reception using the candidate serving cell even without performing the RA procedure.

[0009] Therefore, research on autonomous serving cell handover in a wireless communication system is needed.

[0010] Solution to the problem

[0011] In one aspect, a method performed by a wireless device in a wireless communication system is provided. The method includes: configuring a connection with a serving cell; receiving configurations for one or more candidate serving cells; obtaining the uplink transmission timing of at least one candidate serving cell among the one or more candidate serving cells; detecting a failure related to the serving cell; selecting a specific candidate serving cell among the at least one candidate serving cell for which the uplink transmission timing has been obtained; and performing a serving cell handover from the serving cell to the specific candidate serving cell based on the configuration for the specific candidate serving cell.

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

[0013] Advantages of the invention

[0014] The present disclosure can have various beneficial effects.

[0015] According to some embodiments of the present disclosure, a wireless device can efficiently perform autonomous serving cell handover.

[0016] When the serving cell becomes unavailable due to beam failure or RLF, the UE can continue to perform uplink transmission and downlink reception using the candidate serving cell even without performing the RA procedure.

[0017] In other words, by pre-obtaining the uplink transmission timing, a wireless device can efficiently perform autonomous serving cell handover.

[0018] According to some embodiments of the present disclosure, a wireless communication system can provide an efficient solution for autonomous serving cell handover.

[0019] For example, the network can efficiently provide configurations of candidate serving cells and / or uplink transmission timing for autonomous serving cell handover.

[0020] The beneficial effects that can be obtained through the specific embodiments of the present disclosure are not limited to the beneficial effects listed above. For example, there may be various technical effects that those of ordinary skill in the relevant art can understand and / or derive based on the present disclosure. Therefore, the specific effects of the present disclosure are not limited to those clearly described herein, but may include various effects that can be understood or derived from the technical features of the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 An example of a communication system applying an implementation of the present disclosure is shown.

[0022] Figure 2 An example of a wireless device applying an implementation of the present disclosure is shown.

[0023] Figure 3 An example of a wireless device applying an implementation of the present disclosure is shown.

[0024] Figure 4 Another example of a wireless device applying an implementation of the present disclosure is shown.

[0025] Figure 5 An example of a UE applying an implementation of the present disclosure is shown.

[0026] Figure 6 and Figure 7 An example of a protocol stack in a 3GPP-based wireless communication system applying an implementation of the present disclosure is shown.

[0027] Figure 8 An example of a frame structure in a 3GPP-based wireless communication system applying an implementation of the present disclosure is shown.

[0028] Figure 9 An example of a data flow in a 3GPP NR system applying an implementation of the present disclosure is shown.

[0029] Figure 10a and Figure 10b An example of conditional handover within the AMF / UPF is shown.

[0030] Figure 11 An example of a method for autonomous serving cell handover in a wireless communication system according to some embodiments of the present disclosure is shown.

[0031] Figure 12 An example of a process for autonomous serving cell handover is shown.

[0032] Figure 13 An example of a method for autonomous serving cell handover performed by a UE is shown. DETAILED DESCRIPTION

[0033] The following technologies, devices, and systems can be applied to various wireless multi-access systems. Examples of multi-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 by radio technologies such as Universal Terrestrial Radio Access (UTRA) or CDMA2000. TDMA can be implemented by 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 by 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 the Universal Mobile Telecommunications System (UMTS). The 3rd Generation Partnership Project (3GPP) Long Term Evolution (LTE) is part of the Evolved UMTS (E-UMTS) that uses E-UTRA. 3GPP LTE employs OFDMA in the DL and SC-FDMA in the UL. Long Term Evolution-Advanced (LTE-A) is an evolved version of 3GPP LTE.

[0034] For ease of description, implementations of the present disclosure are mainly described with respect to 3GPP-based wireless communication systems. 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.

[0035] For terms and technologies not specifically described in the terms and technologies adopted in the present disclosure, reference can be made to wireless communication standard documents published before the present disclosure.

[0036] In the present disclosure, "A or B" may mean "only A", "only B", or "both A and B". In other words, "A or B" in the present disclosure can be interpreted as "A and / or B". For example, "A, B, or C" in the present disclosure may mean "only A", "only B", "only C", or "any combination of A, B, and C".

[0037] 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".

[0038] In the present disclosure, "at least one of A and B" may mean "only A", "only B", or "both A and B". Additionally, the expressions "at least one of A or B" or "at least one of A and / or B" in the present disclosure may be interpreted the same as "at least one of A and B".

[0039] 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". Additionally, "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".

[0040] In addition, the parentheses used in the present disclosure may mean "for example". Specifically, when shown as "control information (PDCCH)", "PDCCH" may be presented as an example of "control information". In other words, "control information" in the present disclosure is not limited to "PDCCH", and "PDCCH" may be presented as an example of "control information". Additionally, even when shown as "control information (i.e., PDCCH)", "PDCCH" may be presented as an example of "control information".

[0041] The technical features separately described in one figure in the present disclosure may be implemented separately or simultaneously.

[0042] Although not limited thereto, the various descriptions, functions, processes, suggestions, methods, and / or operation flowcharts of the present disclosure disclosed herein may be applied to various fields that require wireless communication and / or connection (e.g., 5G) between devices.

[0043] 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.

[0044] Figure 1 An example of a communication system to which an implementation of the present disclosure is applied is shown.

[0045] In Figure 1 The 5G usage scenarios shown are only exemplary, and the technical features of the present disclosure may be applied to other 5G usage scenarios not shown in Figure 1 .

[0046] The three main requirement categories of 5G include: (1) the category of enhanced mobile broadband (eMBB), (2) the category of massive machine type communication (mMTC), and (3) the category of ultra-reliable and low-latency communication (URLLC).

[0047] Some use cases may require multiple categories for optimization, and other use cases can focus on only one key performance indicator (KPI). 5G supports such diverse use cases with flexible and reliable methods.

[0048] eMBB far exceeds basic mobile Internet access and covers rich two-way work and media and entertainment applications in cloud and augmented reality. Data is one of the core driving forces of 5G, and in the 5G era, dedicated voice services can be dispensed with for the first time. In 5G, voice is expected to be simply treated as an application using the data connection provided by the communication system. The main reason for increasing service capacity is due to the increase in content size and the increase in the number of applications requiring high data transfer rates. As more and more devices are connected to the Internet, streaming services (audio and video), video calls, and mobile Internet access will be used more widely. Many of these applications require always-on connections to push real-time information and alerts to users. Cloud storage and applications are growing rapidly in the mobile communication platform and can be applied to both work and entertainment. Cloud storage is a special use case that accelerates the growth of uplink data transfer rates. 5G is also used for remote work in the cloud. When using a tactile interface, 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 increases the demand for mobile broadband capabilities. Entertainment is essential for smartphones and tablets anywhere, including high-mobility environments such as trains, vehicles, and airplanes. Other use cases are augmented reality for entertainment and information search. In this case, augmented reality requires very low latency and instantaneous data capacity.

[0049] In addition, one of the most promising 5G use cases involves the ability to smoothly connect embedded sensors in all fields, namely, mMTC. It is expected that the number of potential Internet of Things (IoT) devices will reach 204 billion in 2020. Industrial IoT is one of the categories that play a major role in implementing smart cities, asset tracking, smart utilities, agriculture, and security infrastructure through 5G.

[0050] URLLC includes new services (such as autonomous vehicles) that will transform industries through remote control via the main infrastructure and ultra-reliable / available low-latency links. The levels of reliability and latency are necessary for controlling smart grids, automating industries, implementing robots, and controlling and adjusting drones.

[0051] 5G is a means to provide streams that are evaluated to be in the hundreds of megabits per second to gigabits per second and can complement fiber to the home (FTTH) and cable-based broadband (or DOCSIS). Such high speeds are needed to deliver TV at resolutions 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 nearly immersive motion games. Specific applications may require special network configurations. For example, for VR games, game companies need to incorporate core servers into the edge network servers of network operators to minimize latency.

[0052] Automobiles are expected to be a new and important driver in 5G, along with many use cases for mobile communications in vehicles. For example, the entertainment of passengers requires high simultaneous capacity and mobile broadband with high mobility. This is because future users continue to expect high-quality connections regardless of their location and speed. Another use case in the automotive field is the AR dashboard. The AR dashboard enables the driver to identify objects in the dark in addition to the objects seen through the front window and displays the distance to the objects and the movement of the objects by overlapping information told to the driver. In the future, wireless modules enable communication between vehicles, information exchange between vehicles and supporting infrastructure, and information exchange between vehicles and other connected devices (e.g., devices accompanied by pedestrians). Safety systems guide alternative routes of behavior so that drivers can drive more safely, thereby reducing the risk of accidents. The next stage will be remotely controlled or self-driving vehicles. This requires very high reliability and very fast communication between different self-driving vehicles and between vehicles and infrastructure. In the future, self-driving vehicles will perform all driving activities, and drivers will only focus on abnormal traffic that the vehicle cannot identify. The technical requirements for self-driving vehicles require ultra-low latency and ultra-high reliability, increasing traffic safety to a level that cannot be achieved by humans.

[0053] Smart cities and smart homes / buildings, which are mentioned as smart societies, will be embedded in high-density wireless sensor networks. A distributed network of smart sensors will identify the conditions for cost- and energy-efficient maintenance of the city or home. Similar configurations can be performed for the corresponding home. All temperature sensors, window and heating controllers, burglar alarms, and household appliances are wirelessly connected. Many of these sensors are typically low in data transfer rate, power, and cost. However, certain types of devices may require real-time HD video to perform monitoring.

[0054] The consumption and distribution of energy, including heat or gas, are distributed at a higher level, making automatic control of the distribution sensor network necessary. The smart grid collects information and uses digital information and communication technologies to connect sensors to each other, and thus acts based on the collected information. Since this information can include the behaviors of supply companies and consumers, the smart grid can improve the distribution of fuels such as electricity through methods with efficiency, reliability, economic feasibility, production sustainability, and automation. The smart grid can also be considered as another sensor network with low latency.

[0055] Critical mission applications (e.g., e-health) are one of the 5G usage scenarios. The health segment includes many applications that can enjoy the benefits of mobile communication. The communication system can support teletherapy that provides clinical treatment at remote locations. Teletherapy can help reduce the barrier of distance and improve access to medical services that cannot be continuously obtained in remote rural areas. Teletherapy is also used to perform important treatments and save lives in emergency situations. The wireless sensor network based on mobile communication can provide remote monitoring and sensors for parameters such as heart rate and blood pressure.

[0056] Wireless and mobile communication are gradually becoming important in the field of industrial applications. Wiring is costly in terms of installation and maintenance costs. Therefore, the possibility of replacing cables with reconfigurable radio links is an attractive opportunity in many industrial fields. However, to achieve such a replacement, a wireless connection needs to be established with a latency, reliability, and capacity similar to those of cables, and the management of the wireless connection needs to be simplified. When connecting to 5G is required, low latency and a very low error probability are new requirements.

[0057] Logistics and freight tracking are important use cases of mobile communication, which allow inventory and parcels to be tracked anywhere using location-based information systems. The use cases of logistics and freight tracking generally require low data rates but need location information with a wide range and reliability.

[0058] Refer to Figure 1 , the communication system 1 includes wireless devices 100a to 100f, a base station (BS) 200, and a network 300. Although Figure 1 a 5G network is illustrated as an example of the network of the communication system 1, the implementation of the present disclosure is not limited to 5G systems and can be applied to future communication systems other than 5G systems.

[0059] The BS 200 and the network 300 can be implemented as wireless devices, and a specific wireless device can operate as a BS / network node relative to other wireless devices.

[0060] 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 can be referred to as communication / wireless / 5G devices. Wireless devices 100a to 100f may include, but are not limited to, robot 100a, vehicles 100b-1 and 100b-2, extended reality (XR) device 100c, handheld device 100d, household appliance 100e, IoT device 100f, and artificial intelligence (AI) device / server 400. For example, a vehicle may include a vehicle with wireless communication capabilities, an autonomous driving vehicle, and a vehicle capable of performing communication between vehicles. A vehicle may include an unmanned aerial vehicle (UAV) (e.g., a drone). The XR device may include an AR / VR / hybrid reality (MR) device, and may be implemented in the form of a head-mounted device (HMD), a head-up display (HUD) mounted in a vehicle, a TV, a smartphone, a computer, a wearable device, a household appliance device, a digital sign, a vehicle, a robot, etc. The handheld device may include a smartphone, a smart tablet, a wearable device (e.g., a smartwatch or smart glasses), and a computer (e.g., a notebook). The household appliance may include a TV, a refrigerator, and a washing machine. The IoT device may include sensors and smart meters.

[0061] In the present disclosure, wireless devices 100a to 100f may be referred to as user equipment (UE). For example, the 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 slate personal computer (PC), a tablet PC, a superbook, a vehicle, a vehicle with autonomous driving capabilities, 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 financial device), a security device, a weather / environment device, a device related to 5G services, or a device related to the fourth industrial evolution field.

[0062] The UAV may be, for example, an aircraft that is driven by a wireless control signal without a person on board.

[0063] The VR device may include, for example, a device for implementing an object or background of a virtual world. The AR device may include, for example, a device implemented by connecting an object or background of a virtual world to an object or background of the real world. The MR device may include, for example, a device implemented by merging an object or background of a virtual world into an object or background of the real world. The hologram device may include, for example, a device for implementing a 360-degree stereoscopic image by recording and reproducing stereoscopic information, which uses the interference phenomenon of light generated when two lasers called holographic imaging meet.

[0064] The public safety device may include, for example, an image relay device or an image device wearable on a user's body.

[0065] The MTC device and the IoT device may be, for example, devices that do not require direct human intervention or manipulation. For example, the MTC device and the IoT device may include smart meters, vending machines, thermometers, smart bulbs, door locks, or various sensors.

[0066] The medical device may be, for example, a device for the purpose of diagnosing, treating, alleviating, curing, or preventing diseases. For example, the medical device may be a device for the purpose of diagnosing, treating, alleviating, or correcting injuries or harms. For example, the medical device may be a device for the purpose of inspecting, replacing, or modifying structures or functions. For example, the medical device may be a device for the purpose of regulating pregnancy. For example, the 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.

[0067] The safety device may be, for example, a device installed to prevent possible dangers and maintain safety. For example, the safety device may be a camera, a closed-circuit TV (CCTV), a recorder, or a black box.

[0068] The Fintech device may be, for example, a device capable of providing financial services such as mobile payments. For example, the Fintech device may include a payment device or a point of sale (POS) system.

[0069] The weather / environment device may include, for example, a device for monitoring or predicting the weather / environment.

[0070] The wireless devices 100a to 100f may be connected to the network 300 via the BS200. The AI technology may be applied to the wireless devices 100a to 100f, and the wireless devices 100a to 100f may be connected to the AI server 400 via the network 300. The network 300 may be configured using a 3G network, a 4G (e.g., LTE) network, a 5G (e.g., NR) network, and an ultra 5G network. Although the wireless devices 100a to 100f may communicate with each other via the BS200 / network 300, the wireless devices 100a to 100f may perform direct communication (e.g., sidelink communication) with each other without going through the BS200 / network 300. For example, the vehicles 100b-1 and 100b-2 may perform direct communication (e.g., vehicle-to-vehicle (V2V) / vehicle-to-everything (V2X) communication). The IoT device (e.g., sensor) may perform direct communication with other IoT devices (e.g., sensors) or other wireless devices 100a to 100f.

[0071] Wireless communication / connection 150a, 150b, and 150c may be established between wireless devices 100a to 100f and / or between wireless devices 100a to 100f and BS200 and / or between BS200. In this document, wireless communication / connection may be established through various RATs (e.g., 5G NR) such as uplink / downlink communication 150a, sidelink communication (or device-to-device (D2D) communication) 150b, inter-base station communication 150c (e.g., relay, integrated access and backhaul (IAB)), etc. Wireless devices 100a to 100f and BS200 / wireless devices 100a to 100f may send / receive radio signals to each other through wireless communication / connection 150a, 150b, and 150c. For example, wireless communication / connection 150a, 150b, and 150c may send / receive signals through 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 various proposals of the present disclosure.

[0072] 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, which 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 in the present disclosure may include at least one of ZigBee, Bluetooth, and / or LPWAN considered as low-power communication, and may not be limited to the above names. For example, ZigBee technology may 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 as various names.

[0073] Figure 2An example of a wireless device implementing an embodiment of the present disclosure is shown.

[0074] Referring Figure 2 , the first wireless device 100 and the second wireless device 200 may transmit / receive radio signals to / from an external device via various RATs (e.g., LTE and NR). In Figure 2 , {the first wireless device 100 and the second wireless device 200} may correspond to at least one of {wireless devices 100a to 100f and BS200} attached Figure 1 , {wireless devices 100a to 100f and wireless devices 100a to 100f}, and / or {BS200 and BS200}.

[0075] The first wireless device 100 may include one or more processors 102 and one or more memories 104, and may further 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, procedures, suggestions, methods, and / or operation flowcharts described in the present disclosure. For example, the processor 102 may process the information in the memory 104 to generate first information / signals, and then transmit a radio signal including the first information / signals via the transceiver 106. The processor 102 may receive a radio signal including second information / signals via the transceiver 106, and then store the 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 commands for executing part or all of the processes controlled by the processor 102 or software codes for implementing the descriptions, functions, procedures, suggestions, methods, and / or operation flowcharts described in the present disclosure. Herein, 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 the present disclosure, the first wireless device 100 may represent a communication modem / circuit / chip.

[0076] The second wireless device 200 may include one or more processors 202 and one or more memories 204, and may further 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 operation flowcharts described in the present disclosure. For example, the processor 202 may process the information in 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 the 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 codes including commands for executing a part or all of the processes controlled by the processor 202 or for executing the descriptions, functions, processes, suggestions, methods, and / or operation flowcharts described in the present 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 through 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 the RF unit. In the present disclosure, the second wireless device 200 may represent a communication modem / circuit / chip.

[0077] In the following, the hardware elements of 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 media 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, procedures, suggestions, methods, and / or operation 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, procedures, suggestions, methods, and / or operation flowcharts disclosed in the present disclosure. One or more processors 102 and 202 may generate signals (e.g., baseband signals) including PDUs, SDUs, messages, control information, data, or information according to the descriptions, functions, procedures, suggestions, methods, and / or operation flowcharts disclosed in the present disclosure, and provide the generated signals to one or more transceivers 106 and 206. One or more processors 102 and 202 may receive signals (e.g., baseband signals) from one or more transceivers 106 and 206, and obtain PDUs, SDUs, messages, control information, data, or information according to the descriptions, functions, procedures, suggestions, methods, and / or operation flowcharts disclosed in the present disclosure.

[0078] One or more processors 102 and 202 may be referred to as a controller, microcontroller, microprocessor, or microcomputer. 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 operation flowcharts disclosed in the present disclosure may be implemented using firmware or software, and the firmware or software may be configured to include modules, processes, or functions. The firmware or software configured to execute the descriptions, functions, processes, suggestions, methods, and / or operation flowcharts disclosed in the present disclosure may be included in one or more processors 102 and 202, or stored in one or more memories 104 and 204, and thus driven by one or more processors 102 and 202. The descriptions, functions, processes, suggestions, methods, and / or operation flowcharts disclosed in the present disclosure may be implemented using firmware or software in the form of code, commands, and / or sets of commands.

[0079] One or more memories 104 and 204 may 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 may be configured by read only memory (ROM), random access memory (RAM), electrically erasable programmable read only memory (EPROM), flash memory, hard disk drive, registers, cache memory, computer readable storage medium, and / or a combination thereof. One or more memories 104 and 204 may be located inside and / or outside one or more processors 102 and 202. One or more memories 104 and 204 may be connected to one or more processors 102 and 202 through various technologies such as wired or wireless connections.

[0080] One or more transceivers 106 and 206 may send 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 may 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 may be connected to one or more processors 102 and 202 and send and receive radio signals. For example, one or more processors 102 and 202 may execute control such that one or more transceivers 106 and 206 may send user data, control information, or radio signals to one or more other devices. One or more processors 102 and 202 may execute control such that one or more transceivers 106 and 206 may receive user data, control information, or radio signals from one or more other devices.

[0081] One or more transceivers 106 and 206 may be connected to one or more antennas 108 and 208, and one or more transceivers 106 and 206 may be configured to send 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 this disclosure through one or more antennas 108 and 208. In this disclosure, one or more antennas may be multiple physical antennas or multiple logical antennas (e.g., antenna ports).

[0082] One or more transceivers 106 and 206 may convert the received radio signals / channels, etc. from RF band signals to baseband signals in order to process the received user data, control information, radio signals / channels, etc. One or more transceivers 106 and 206 may convert the 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, transceivers 106 and 206 may up-convert an OFDM baseband signal to a carrier frequency through their (analog) oscillators and / or filters under the control of processors 102 and 202, and send the up-converted OFDM signal of the carrier frequency. Transceivers 106 and 206 may receive an OFDM signal of the carrier frequency, and down-convert the OFDM signal to an OFDM baseband signal through their (analog) oscillators and / or filters under the control of processors 102 and 202.

[0083] In an implementation of the present disclosure, the UE may operate as a transmitting device in the uplink (UL) and as a receiving device in the downlink (DL). In an implementation of the present disclosure, the 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 mainly assumed that the first wireless device 100 acts as the UE and the second wireless device 200 acts as the BS. For example, a processor 102 connected to, installed on, or initiated in the first wireless device 100 may be configured to perform UE behavior according to an implementation of the present disclosure, or control a transceiver 106 to perform UE behavior according to an implementation of the present disclosure. A processor 202 connected to, installed on, or initiated in the second wireless device 200 may be configured to perform BS behavior according to an implementation of the present disclosure, or control a transceiver 206 to perform BS behavior according to an implementation of the present disclosure.

[0084] In the present disclosure, the BS is also referred to as a Node B (NB), an eNodeB (eNB), or a gNB.

[0085] Figure 3 An example of a wireless device to which an implementation of the present disclosure is applied is shown.

[0086] The wireless device may be implemented in various forms according to use cases / services (refer to Figure 1 ).

[0087] Refer to Figure 3 , the wireless devices 100 and 200 may correspond to Figure 2 's wireless devices 100 and 200, and 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 additional components 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 of Figure 2 and / or Figure 2 one or more memories 104 and 204 of Figure 2One or more antennas 108 and 208. The 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 may control the electrical / mechanical operations of each of the wireless devices 100 and 200 based on programs / codes / commands / information stored in the memory unit 130. The control unit 120 may transmit the information stored in the memory unit 130 to the outside (e.g., other communication devices) via the communication unit 110 through a wireless / wired interface, or store the information received from the outside (e.g., other communication devices) through the wireless / wired interface in the memory unit 130 via the communication unit 110.

[0088] The additional components 140 may be configured differently according to the types of the wireless devices 100 and 200. For example, the additional components 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 implemented in, but not limited to, the form of robots ( Figure 1 100a), vehicles ( Figure 1 100b-1 and 100b-2), XR devices ( Figure 1 100c), handheld devices ( Figure 1 100d), household appliances ( Figure 1 100e), IoT devices ( Figure 1 100f), digital broadcast terminals, hologram devices, public safety devices, MTC devices, medical devices, Fintech devices (or financial devices), security devices, climate / environment devices, AI servers / devices ( Figure 1 400), BSSs ( Figure 1 200), network nodes, etc. The wireless devices 100 and 200 may be used in mobile or fixed positions according to usage examples / services.

[0089] In Figure 3In [the description], various elements, components, units / parts, and / or modules in the wireless devices 100 and 200 can be connected to each other through a wired interface, or at least a part of them can be wirelessly connected through the communication unit 110. For example, in each of the wireless devices 100 and 200, the control unit 120 and the communication unit 110 can be connected by a wired connection, and the control unit 120 and the first units (e.g., 130 and 140) can be wirelessly connected through the communication unit 110. Each element, component, unit / part, and / or module within the wireless devices 100 and 200 can also include one or more elements. For example, the control unit 120 can be configured by a group of one or more processors. As an example, the control unit 120 can be configured by a group of communication control processors, application processors (APs), electronic control units (ECUs), graphics processing units, and memory control processors. As another example, the memory unit 130 can be configured by RAM, DRAM, ROM, flash memory, volatile memory, non-volatile memory, and / or a combination thereof.

[0090] Figure 4 Another example of a wireless device implementing the present disclosure is shown.

[0091] Referring to Figure 4 , the wireless devices 100 and 200 can correspond to Figure 2 the wireless devices 100 and 200 [described above], and can be configured by various elements, components, units / parts, and / or modules.

[0092] The first wireless device 100 can include at least one transceiver such as a transceiver 106, and at least one processing chip such as a processing chip 101. The processing chip 101 can include at least one processor such as a processor 102 and at least one memory such as a memory 104. The memory 104 can be operably connected to the processor 102. The memory 104 can store various types of information and / or instructions. The memory 104 can store software code 105, and the software code 105 implements instructions that, when executed by the processor 102, perform the descriptions, functions, processes, suggestions, methods, and / or operation flowcharts disclosed in the present disclosure. For example, the software code 105 can implement instructions that, when executed by the processor 102, perform the descriptions, functions, processes, suggestions, methods, and / or operation flowcharts disclosed in the present disclosure. For example, the software code 105 can control the processor 102 to execute one or more protocols. For example, the software code 105 can control the processor 102 to execute one or more layers of a radio interface protocol.

[0093] 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. The processing chip 201 may include at least one processor such as processor 202 and at least one memory such as memory 204. The memory 204 may be operably connected to the processor 202. The memory 204 may store various types of information and / or instructions. The memory 204 may store software code 205, and the software code 205 implements instructions for executing the descriptions, functions, processes, suggestions, methods, and / or operation flowcharts disclosed in the present disclosure when executed by the processor 202. For example, the software code 205 may implement instructions for executing the descriptions, functions, processes, suggestions, methods, and / or operation flowcharts disclosed in the present disclosure when executed by the processor 202. For example, the software code 205 may control the processor 202 to execute one or more protocols. For example, the software code 205 may control the processor 202 to execute one or more layers of a radio interface protocol.

[0094] Figure 5 An example of a UE implementing the present disclosure is shown.

[0095] Referring to Figure 5 , UE 100 may correspond to the first wireless device 100 attached Figure 2 and / or Figure 4 the first wireless device 100.

[0096] UE 100 includes a processor 102, a memory 104, a transceiver 106, one or more antennas 108, a power management module 110, a battery 1112, a display 114, a keyboard 116, a subscriber identity module (SIM) card 118, a speaker 120, and a microphone 122.

[0097] The processor 102 may be configured to implement the descriptions, functions, processes, suggestions, methods, and / or operation 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 operation flowcharts disclosed in the present disclosure. Layers of a radio interface protocol may be implemented in the processor 102. The processor 102 may include an ASIC, other chip sets, 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 can be found in manufactured SNAPDRAGON TM series processors, manufactured EXYNOSTM Series processors, The A series processors manufactured, The HELIO manufactured, TM Series processors, The ATOM manufactured, TM Series processors or corresponding next-generation processors.

[0098] Memory 104 is operatively coupled to processor 102 and stores various information for operating processor 102. Memory 104 may include ROM, RAM, flash memory, memory cards, storage media, and / or other storage devices. When an implementation is realized in software, the techniques described herein may be realized by modules (e.g., procedures, functions, etc.) that execute the descriptions, functions, procedures, suggestions, methods, and / or operation flowcharts disclosed in this disclosure. The modules may be stored in memory 104 and executed by processor 102. Memory 104 may be implemented within or external to processor 102, in which case memory 104 may be communicatively coupled to processor 102 via various means known in the art.

[0099] Transceiver 106 is operatively coupled to processor 102 and transmits and / or receives radio signals. Transceiver 106 includes a transmitter and a receiver. Transceiver 106 may include baseband circuitry for processing radio frequency signals. Transceiver 106 controls one or more antennas 108 to transmit and / or receive radio signals.

[0100] Power management module 110 manages the power of processor 102 and / or transceiver 106. Battery 112 supplies power to power management module 110.

[0101] Display 114 outputs the results processed by processor 102. Keyboard 116 receives inputs to be used by processor 102. Keyboard 16 may be displayed on display 114.

[0102] SIM card 118 is an integrated circuit designed to securely store the International Mobile Subscriber Identity (IMSI) number and its associated keys, which are used to identify and authenticate subscribers on mobile phone devices (such as mobile phones and computers). Contact information may also be stored on many SIM cards.

[0103] Speaker 120 outputs sound-related results processed by processor 102. Microphone 122 receives sound-related inputs to be used by processor 102.

[0104] Figure 6 and Figure 7 Shows an example of a protocol stack in a 3GPP-based wireless communication system implementing the embodiments of the present disclosure.

[0105] Specifically, Figure 6 illustrates an example of the radio interface user plane protocol stack between a UE and a BS, and Figure 7 illustrates an example of the radio interface control plane protocol stack between a UE and a BS. The control plane refers to the path through which control messages for managing calls made by the UE and the network are transmitted. The user plane refers to the path through which data generated in the application layer (e.g., voice data or Internet packet data) is transmitted. Referring to Figure 6 , the user plane protocol stack can be divided into Layer 1 (i.e., the PHY layer) and Layer 2. Referring to Figure 7 , the control plane protocol stack can be divided into Layer 1 (i.e., the PHY layer), Layer 2, Layer 3 (e.g., the RRC layer), and the non-access stratum (NAS) layer. Layer 1, Layer 2, and Layer 3 are referred to as the access stratum (AS).

[0106] In the 3GPP LTE system, Layer 2 is separated into the following sub-layers: MAC, RLC, and PDCP. In the 3GPP NR system, Layer 2 is separated into the following sub-layers: MAC, RLC, PDCP, and SDAP. The PHY layer provides a transport channel to the MAC sub-layer, the MAC sub-layer provides a logical channel to the RLC sub-layer, the RLC sub-layer provides an RLC channel to the PDCP sub-layer, and the PDCP sub-layer provides a radio bearer to the SDAP sub-layer. The SDAP sub-layer provides a quality of service (QoS) flow to the 5G core network.

[0107] In the 3GPP NR system, the main services and functions of the MAC sub-layer include: mapping between logical channels and transport channels; multiplexing / demultiplexing MAC SDUs belonging to one or different logical channels into / from transport blocks (TBs) delivered to / from the physical layer on the transport channel; 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 one UE through logical channel prioritization; padding. A single MAC entity can support multiple parameter sets, transmission timings, and cells. The mapping restriction in logical channel prioritization controls which parameter set(s), cell(s), and transmission timing a logical channel can use.

[0108] The MAC provides different types of data transfer services. To accommodate different types of data transfer services, multiple types of logical channels are defined, i.e., each logical channel supports the transfer of a specific type of information. Each logical channel type is defined by what type of information is transferred. Logical channels are divided into two groups: control channels and traffic channels. Control channels are only used for the transfer of control plane information, and traffic channels are only used for the transfer of user plane information. The Broadcast Control Channel (BCCH) is a downlink logical channel used for broadcasting system control information, the Paging Control Channel (PCCH) is a downlink logical channel that transfers 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 for sending control information between the UE and the network and is used by UEs that do not have an RRC connection to 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 that have an RRC connection. The Dedicated Traffic Channel (DTCH) is a point-to-point logical channel dedicated to a single UE and is used to transfer user information. The DTCH can exist in both the uplink and the downlink. In the downlink, there are the following connections between logical channels and transport channels: the BCCH can be mapped to the Broadcast Channel (BCH); the BCCH can be mapped to the Downlink Shared Channel (DL-SCH); the PCCH can be mapped to the Paging Channel (PCH); the CCCH can be mapped to the DL-SCH; the DCCH can be mapped to the DL-SCH; and the DTCH can be mapped to the DL-SCH. In the uplink, there are the following connections between logical channels and transport channels: the CCCH can be mapped to the Uplink Shared Channel (UL-SCH); the DCCH can be mapped to the UL-SCH; and the DTCH can be mapped to the UL-SCH.

[0109] The RLC sublayer supports three transfer modes: Transparent Mode (TM), Unacknowledged Mode (UM), and Acknowledged Mode (AM). The RLC configuration is per logical channel, without dependence on parameter sets and / or transfer durations. In the 3GPP NR system, the main services and functions of the RLC sublayer depend on the transfer mode and include: transfer of upper layer PDUs; sequence numbering (UM and AM) independent of the sequence numbering in PDCP; error correction via ARQ (only AM); segmentation (AM and UM) and re-segmentation (only AM) of RLC SDUs; reassembly of SDUs (AM and UM); duplicate detection (only AM); RLC SDU discard (AM and UM); RLC re-establishment; protocol error detection (only AM).

[0110] 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); transfer of user data; reordering and duplicate detection; in-sequence delivery; PDCP PDU routing (in the case of split bearers); retransmission of PDCP SDUs; encryption, decryption, and integrity protection; PDCP SDU discard; PDCP re-establishment and data recovery for RLC AM; PDCP status reporting for RLC AM; duplication of PDCP PDUs and discard indication of duplicates to the lower layer. The main services and functions of the PDCP sublayer for the control plane include: sequence numbering; encryption, decryption, and integrity protection; transfer of control plane data; reordering and duplicate detection; in-sequence delivery; duplication of PDCP PDUs and discard indication of duplicates to the lower layer.

[0111] In the 3GPP NR system, the main services and functions of SDAP include: mapping between QoS flows and data radio bearers; marking the QoS flow ID (QFI) in both DL packets and UL packets. A single protocol entity of SDAP is configured for each individual PDU session.

[0112] In the 3GPP NR system, the main services and functions of the RRC sublayer include: broadcasting of system information related to AS and NAS; paging initiated by 5GC or NG-RAN; establishment, maintenance, and release of the RRC connection between the 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, inter-RAT mobility); QoS management functions; UE measurement reporting and control of reporting; detection and recovery of radio link failures; NAS message transfer from the UE to the NAS / from the NAS to the UE.

[0113] Figure 8 The frame structure in a 3GPP-based wireless communication system implementing the embodiments of the present disclosure is shown.

[0114] Figure 8The frame structure shown is merely exemplary, and the number of sub - frames, the number of time slots, and / or the number of symbols in a frame can be variably changed. In a 3GPP - based wireless communication system, OFDM parameter sets (e.g., sub - carrier spacing (SCS), transmission time interval (TTI) duration) can be configured differently among multiple cells aggregated for one UE. For example, if a UE is configured with different SCSs for cells targeted for cell aggregation, the (absolute - time) duration of a time resource (e.g., sub - frame, time slot, or TTI) including the same number of symbols can be different among the aggregated cells. Herein, a symbol can include an OFDM symbol (or CP - OFDM symbol), an SC - FDMA symbol (or discrete Fourier transform - spread - OFDM (DFT - s - OFDM) symbol).

[0115] Referring to Figure 8 , downlink and uplink transmissions are organized into frames. Each frame has a duration of T f = 10 ms. Each frame is divided into two half - frames, where each half - frame has a duration of 5 ms. Each half - frame includes 5 sub - frames, where the duration T sf of each sub - frame is 1 ms. Each sub - frame is divided into time slots, and the number of time slots in a sub - frame depends on the sub - carrier spacing. Each time slot includes 14 or 12 OFDM symbols based on the cyclic prefix (CP). In normal CP, each time slot includes 14 OFDM symbols, and in extended CP, each time slot includes 12 OFDM symbols. The parameter set is based on an exponentially scalable sub - carrier spacing Δf = 2 u * 15 kHz.

[0116] Table 1 shows the number of OFDM symbols N u * per time slot according to the sub - carrier spacing Δf = 2 slot symb , the number of time slots N frame,u slot per frame, and the number of time slots N subframe,u slot per sub - frame for normal CP.

[0117] [Table 1]

[0118] 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

[0119] Table 2 shows the number of OFDM symbols N u * per time slot according to the sub - carrier spacing Δf = 2 slot symb , the number of time slots N fame,u slot , and the number of time slots N per sub - frame for extended CPsubframne,u slot .

[0120] [Table 2]

[0121] u <![CDATA[N slot symb > <![CDATA[N frame,u slot > <![CDATA[N subframe，u slot > 2 12 40 4

[0122] A time slot includes a plurality of symbols (e.g., 14 or 12 symbols) in the time domain. For each parameter set (e.g., subcarrier spacing) and carrier, starting from a common resource block (CRB) N indicated by high layer signaling (e.g., RRC signaling), a resource grid of N subcarriers and N OFDM symbols is defined, where N is the number of resource blocks (RBs) in the resource grid, and the subscript x is DL for downlink and UL for uplink. N is the number of subcarriers per RB. In a 3GPP-based wireless communication system, N is typically 12. For a given antenna port p, subcarrier spacing configuration u, and transmission direction (DL or UL), there is a resource grid. The carrier bandwidth N for subcarrier spacing configuration u is given by high layer 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 a 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. start,u grid starting size，u grid，x *N RB sc subcarriers and N subframe,u symb OFDM symbols is defined, where N size,u grid，x is the number of resource blocks (RBs) in the resource grid, and the subscript x is DL for downlink and UL for uplink. N RB sc is the number of subcarriers per RB. In a 3GPP-based wireless communication system, N RB sc is typically 12. For a given antenna port p, subcarrier spacing configuration u, and transmission direction (DL or UL), there is a resource grid. The carrier bandwidth N for subcarrier spacing configuration u is given by high layer 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 a 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. size,u grid is given by high layer 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 a 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.

[0123] In the 3GPP NR system, RBs are classified into CRBs and physical resource blocks (PRBs). CRBs are numbered upwards starting 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 the 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. The relationship between the physical resource block n in bandwidth part i PRB and the common resource block n CRB is as follows: nPRB = n CRB + N size BWP,i , where N size BWP，i is the common resource block where the bandwidth part starts relative to CRB 0. The BWP includes a plurality of consecutive RBs. A carrier may include up to N (e.g., 5) BWPs. A UE may be configured with one or more BWPs on a given component carrier. Among the BWPs configured for a UE, only one BWP can be active at a time. The active BWP defines the operating bandwidth of the UE within the operating bandwidth of the cell.

[0124] NR frequency bands 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 frequency ranges of the two types (FR1 and FR2) can be as shown in Table 3 below. For ease of explanation, in the frequency ranges used in the NR system, FR1 can represent the "sub-6 GHz range" and FR2 can represent the "above 6 GHz range" and can be referred to as millimeter wave (mmW).

[0125] [Table 3]

[0126] Frequency range name Corresponding frequency range Subcarrier spacing FR1 450 MHz - 6000 MHz 15, 30, 60 kHz FR2 24250 MHz - 52600 MHz 60, 120, 240 kHz

[0127] As described above, the numerical values of the frequency ranges of the NR system can be changed. For example, FR1 can include a frequency band from 410 MHz to 7125 MHz, as shown in Table 4 below. That is to say, 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 vehicle communication (e.g., autonomous driving).

[0128] [Table 4]

[0129] Frequency range name Corresponding frequency range Subcarrier spacing FR1 410 MHz - 7125 MHz 15, 30, 60 kHz FR2 24250 MHz - 52600 MHz 60, 120, 240 kHz

[0130] In the present disclosure, the term "cell" may refer to a geographical area of a communication system provided by one or more nodes 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 radio resources (e.g., time-frequency resources) is associated with a bandwidth, which is the frequency range configured by the carrier. A "cell" associated with radio resources is defined by a combination of downlink resources and uplink resources (e.g., a combination of a DL component carrier (CC) and a UL CC). A cell can be configured by only downlink resources or can be configured by both downlink resources and uplink resources. Since the DL coverage (which is the range within which a node can send a valid signal) and the UL coverage (which is the range within which a node can receive a valid signal from a UE) depend on the carrier carrying the signal, the coverage of a node can be associated with the coverage of a "cell" of the radio resources used by the node. Thus, the term "cell" can be used to sometimes represent the service coverage of a node, at other times represent radio resources, or at other times represent the range within which a signal using the radio resources can reach with an effective strength.

[0131] In CA, two or more CCs are aggregated. The UE can receive or transmit on one or more CCs simultaneously according to 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. At RRC connection establishment / re - establishment / handoff, one serving cell provides NAS mobility information, and at RRC connection re - establishment / handoff, one serving cell provides security input. This cell is called the primary cell (PCell). The PCell is the cell operating on the primary frequency where the UE performs the initial connection establishment process or initiates the connection re - establishment process. Depending on the UE capabilities, secondary cells (SCells) can be configured to form a set of serving cells together with the PCell. An SCell is a cell that provides additional radio resources on top of the special cell (PCell). Thus, the set of configured serving cells for a 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 master 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 active. The MCG is the set of serving cells associated with the master node, which includes the SpCell (PCell) and optionally one or more SCells. For a UE configured with DC, the SCG is a subset of the serving cells associated with the secondary node, which includes the PSCell and zero or more SCells. For a UE in RRC_CONNECTED not configured with CA / DC, there is only one serving cell consisting of the PCell. For a UE in RRC_CONNECTED configured with CA / DC, the term "serving cell" is used to represent the set of cells consisting of the SpCell and all SCells. In DC, two MAC entities are configured in the UE: one for the MCG and one for the SCG.

[0132] Figure 9 Fig. shows an example of data flow in a 3GPP NR system implementing the present disclosure.

[0133] Refer to Figure 9 ,"RB" represents radio bearer, and "H" represents header. Radio bearers are classified into two groups: DRB for user - plane data and SRB for control - plane data. MAC PDUs are sent / received to / from external devices through the PHY layer using radio resources. The MAC PDU arrives at the PHY layer in the form of a transport block.

[0134] 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, the uplink control information (UCI) is mapped to the physical PUCCH, and the downlink control information (DCI) is mapped to the PDCCH. The MAC PDU associated with UL-SCH is sent by the UE via PUSCH based on UL grant, and the MAC PDU associated with DL-SCH is sent by the BS via PDSCH based on DL assignment.

[0135] In the following, technical features related to conditional reconfiguration (e.g., conditional handover (CHO), conditional PSCell addition (CPA), conditional PSCell change (CPC)) are described. Reference can be made to Section 5.3.5.13 of 3GPP TS 38.331 v17.2.0.

[0136] The network configures one or more candidate target SpCells for the UE in conditional reconfiguration. The UE evaluates the conditions of each configured candidate target SpCell. The UE applies the conditional reconfiguration associated with one of the target SpCells that meet the associated execution conditions. The network provides the configuration parameters for the target SpCell in the ConditionalReconfiguration IE.

[0137] The UE performs the following actions based on the received ConditionalReconfiguration IE:

[0138] 1> If ConditionalReconfiguration contains condReconfigToRemoveList:

[0139] 2> Perform the conditional reconfiguration removal procedure;

[0140] 1> If ConditionalReconfiguration contains condReconfigToAddModList:

[0141] 2> Perform the conditional reconfiguration addition / modification;

[0142] - Conditional reconfiguration addition / modification

[0143] For each condReconfigId received in the condReconfigToAddModList IE, the UE shall:

[0144] 1> If there is an entry in condReconfigToAddModList within VarConditionalReconfig that has a matching condReconfigId:

[0145] 2> If the entry in condReconfigToAddModList includes condExecutionCond or condExecutionCondSCG;

[0146] 3> Replace the condExecutionCond or condExecutionCondSCG in VarConditionalReconfig with the value received for that condReconfigId;

[0147] 2> If the entry in CondReConfigToAddModList includes condRRCReconfig;

[0148] 3> Replace the condRRCReconfig within VarConditionalReconfig with the value received for that condReconfigId;

[0149] 1> Otherwise:

[0150] 2> Add a new entry for that condReconfigId in VarConditionalReconfig;

[0151] 1> Perform conditional reconfiguration evaluation;

[0152] - Conditional reconfiguration evaluation

[0153] The UE shall:

[0154] 1> For each condReconfigId within VarConditionalReconfig:

[0155] 2> If the RRCReconfiguration within condRRCReconfig includes a masterCellGroup that contains reconfigurationWithSync, consider the cell with a physical cell identity that matches the value indicated in ServingCellConfigCommon included in ReconfigWithSync within the masterCellGroup in the received condRRCReconfig as the applicable cell;

[0156] 2> If the RRCReconfiguration within condRRCReconfig includes a secondaryCellGroup containing reconfigurationWithSync, a cell having a physical cell identity matching the value indicated in ServingCellConfigCommon included in reconfigurationWithSync within the secondaryCellGroup within the received condRRCReconfig is considered an applicable cell;

[0157] 2> If condExecutionCondSCG is configured:

[0158] 3> In the remaining procedures, each measId indicated in condExecutionCondSCG is considered as the measId in VarMeasConfig associated with SCGmeasConfig;

[0159] 2> If condExecutionCond is configured:

[0160] 3> If it is configured via SRB3 or within nr-SCG or nr-SecondaryCellGroupConfig via SRB1:

[0161] 4> In the remaining procedures, each measId indicated in condExecutionCond is considered as the measId in VarMeasConfig associated with SCGmeasConfig;

[0162] 3> Otherwise:

[0163] 4> In the remaining procedures, each measId indicated in condExecutionCond is considered as the measId in VarMeasConfig associated with MCGmeasConfig;

[0164] 2> For each measId included in the measIdList within VarMeasConfig indicated in condExecutionCond or condExecutionCondSCG associated with condReconfigId:

[0165] 3> If condEventId is associated with condEventT1 and if the entry condition applicable to this event associated with condReconfigId (i.e., the event corresponding to the condEventId of the corresponding condTriggerConfig within VarConditionalReconfig) is satisfied for the applicable cell; or

[0166] 3> If condEventId is associated with condEventD1 and if the entry condition applicable to this event associated with condReconfigId (i.e., the event corresponding to the condEventId of the corresponding condTriggerConfig within VarConditionalReconfig) is satisfied for the applicable cell during the corresponding timeToTrigger defined for this event within VarConditionalReconfig; or

[0167] 3> If condEventId is associated with condEventA3, condEventA4 or condEventA5 and if the entry condition applicable to this event associated with condReconfigId (i.e., the event corresponding to the condEventId of the corresponding condTriggerConfig within VarConditionalReconfig) is satisfied for all measurements after layer 3 filtering performed during the corresponding timeToTrigger defined for this event within VarConditionalReconfig for the applicable cell:

[0168] 4> The event associated with measId is considered satisfied;

[0169] 3> If the measId of this event associated with condReconfigId has been modified; or

[0170] 3> If condEventId is associated with condEventT1 and if the exit condition applicable to this event associated with condReconfigId (i.e., the event corresponding to the condEventId of the corresponding condTriggerConfig within VarConditionalReconfig) is satisfied for the applicable cell; or

[0171] 3> If condEventId is associated with condEventD1, and if the leaving condition applicable to this event associated with condReconfigId (i.e., the event corresponding to the condEventId of the corresponding condTriggerConfig within VarConditionalReconfig) is satisfied for the applicable cell during the corresponding timeToTrigger defined for this event within VarConditionalReconfig; or

[0172] 3> If condEventId is associated with condEventA3, condEventA4 or condEventA5, and if the leaving condition applicable to this event associated with condReconfigId (i.e., the event corresponding to the condEventId of the corresponding condTriggerConfig within VarConditionalReconfig) is satisfied for all measurements after layer 3 filtering performed during the corresponding timeToTrigger defined for this event within VarConditionalReconfig for the applicable cell:

[0173] 4> The event associated with this measId is considered not satisfied;

[0174] 2> If the events associated with all measIds within the condTriggerConfig of the target candidate cell within the stored condRRCReconfig are satisfied:

[0175] 3> The target candidate cell within the stored condRRCReconfig associated with this condReconfigId is considered as the triggering cell;

[0176] 3> Initiate conditional reconfiguration execution;

[0177] For each condReconfigId, up to 2 MeasIds can be configured. The conditional reconfiguration events for the 2 MeasIds can have the same or different event conditions, trigger quantities, trigger times and trigger thresholds.

[0178] - Conditional reconfiguration execution

[0179] The UE shall:

[0180] 1> If there are more than one triggered cells:

[0181] 2> Select one of the triggered cells as the selected cell for conditional reconfiguration execution;

[0182] 1> Otherwise:

[0183] 2> Treat the triggered cell as the selected cell for conditional reconfiguration execution;

[0184] 1> For the selected cell of conditional reconfiguration execution:

[0185] 2> Apply the stored condRRCReconfig of the selected cell and execute the action;

[0186] If multiple NR cells are triggered during conditional reconfiguration execution, which one to select is determined by the UE implementation. For example, the UE considers the beam and beam quality to select one of the triggered cells for execution.

[0187] -ReportConfigNR

[0188] IE ReportConfigNR specifies the criteria for triggering NR measurement report events or CHO, CPA, or CPC events. For events marked as AN and N equal to 1, 2, etc., the measurement report events and CHO, CPA, or CPC events are based on cell measurement results, which can be obtained based on SS / PBCH blocks or CSI-RS.

[0189] Event A1: The serving becomes better than the absolute threshold;

[0190] Event A2: The serving becomes worse than the absolute threshold;

[0191] Event A3: The neighbor becomes better than the PCell / PSCell by a certain amount of offset;

[0192] Event A4: The neighbor becomes better than the absolute threshold;

[0193] Event A5: The PCell / PSCell becomes worse than the absolute threshold 1, and the neighbor / SCell becomes better than another absolute threshold 2;

[0194] Event A6: The neighbor becomes better than the SCell by a certain amount of offset;

[0195] Event D1: The distance between the UE and the reference location referenceLocation1 becomes greater than the configured threshold 1 Thresh1, and the distance between the UE and the reference location referenceLocation2 becomes shorter than the configured threshold Thresh2;

[0196] CondEvent A3: The conditional reconfiguration candidate becomes better than the PCell / PSCell by a certain amount of offset;

[0197] CondEvent A4: The conditional reconfiguration candidate becomes better than the absolute threshold;

[0198] CondEvent A5: The PCell / PSCell becomes worse than absolute threshold 1, and the conditional reconfiguration candidate becomes better than another absolute threshold 2;

[0199] CondEvent D1: The distance between the UE and the reference location referenceLocation1 becomes greater than the configured threshold Thresh1, and the distance between the UE and the reference location referenceLocation2 of the conditional reconfiguration candidate becomes shorter than the configured threshold Thresh2;

[0200] CondEvent T1: The time measured at the UE becomes greater than the configured threshold Thresh1 but less than Thresh2;

[0201] Event X1: The serving L2 U2N relay UE becomes worse than absolute threshold 1, and the NR cell becomes better than another absolute threshold 2;

[0202] Event X2: The serving L2 U2N relay UE becomes worse than the absolute threshold;

[0203] For Event I1, the measurement report event is based on the CLI measurement result, which can be obtained based on SRS-RSRP or CLI-RSSI.

[0204] Event IL: The interference becomes higher than the absolute threshold.

[0205] In the following, the technical features related to the actions related to radio link failure are described. Reference can be made to Section 5.3.5.10 of 3GPP TS38.331 v17.2.0.

[0206] - Detect physical layer problems under RRC_CONNECTED

[0207] The UE shall:

[0208] 1> If any DAPS bearers are configured, when receiving N310 consecutive "out-of-sync" indications for the source SpCell from the lower layer and T304 is running:

[0209] 2> Start timer T310 for the source SpCell.

[0210] 1> When receiving N310 consecutive "out-of-sync" indications for the SpCell from the lower layer when T300, T301, T304, T311, T316, and T319 are not running:

[0211] 2>Start timer T310 for the corresponding SpCell.

[0212] -Recovery of physical layer problems

[0213] When the UE receives N311 consecutive "synchronization" indications for the SpCell from the lower layer while T310 is running, the UE shall:

[0214] 1>Stop timer T310 for the corresponding SpCell.

[0215] 1>Stop timer T312 for the corresponding SpCell (if it is running).

[0216] In this case, the UE maintains the RRC connection without explicit signaling, i.e., the UE maintains the entire radio resource configuration.

[0217] The period during which L1 neither reports "synchronization" nor "asynchronization" does not affect the evaluation of the number of consecutive "synchronization" or "asynchronization" indications.

[0218] -Detection of radio link failure

[0219] The UE shall:

[0220] 1>If any DAPS bearers are configured and T304 is running:

[0221] 2>When T310 expires in the source SpCell; or

[0222] 2>When a random access problem indication from the source MCG MAC; or

[0223] 2>When an indication that the maximum retransmission count has been reached from the source MCG RLC; or

[0224] 2>When a consistent uplink LBT failure indication from the source MCG MAC:

[0225] 3>Consider that a radio link failure has been detected for the source MCG (i.e., source RLF);

[0226] 3>Suspend the transmission and reception of all DRBs and multicast MRBs in the source MCG;

[0227] 3>Reset the MAC for the source MCG;

[0228] 3>Release the source connection.

[0229] 1>Otherwise:

[0230] 2>During a DAPS handover: The following only applies to the target PCell;

[0231] 2> When T310 expires in the PCell; or

[0232] 2> When T312 expires in the PCell; or

[0233] 2> When there is a random access problem indication from the MCG MAC when T300, T301, T304, T311, and T319 are not running; or

[0234] 2> When there is an indication from the MCG RLC that the maximum retransmission count has been reached; or

[0235] 2> If connected as an IAB node, when a BH RLF indication is received from the MCG on the BAP entity; or

[0236] 2> When there is a consistent uplink LBT failure indication from the MCG MAC when T304 is not running:

[0237] 3> If the indication is from the MCG RLC and CA duplication is configured and activated for the MCG, and for the corresponding logical channel, allowedServingCells only includes SCell:

[0238] 4> Initiate a failure information procedure to report the RLC failure.

[0239] 3> Otherwise:

[0240] 4> Consider that a radio link failure has been detected for the MCG (i.e., MCG RLF);

[0241] 4> Discard any segments of the stored segmented RRC messages;

[0242] 4> If AS security has not been activated:

[0243] 5> Perform an action when entering RRC_IDLE, where the release reason is "other"; -

[0244] 4> Otherwise, if AS security has been activated, but SRB2 and at least one DRB or multicast MRB or (for IAB) SRB2 have not been established:

[0245] 5> Store the radio link failure information in VarRLF-Report;

[0246] 5> Perform an action when entering RRC_IDLE, where the release reason is "RRC connection failure";

[0247] 4> Otherwise:

[0248] 5> Store the radio link failure information in VarRLF-Report;

[0249] 5> If T316 is configured; and

[0250] 5> If the SCG transmission is not paused; and

[0251] 5> If the SCG is not deactivated; and

[0252] 5> If neither PSCell change nor PSCell addition is in progress (i.e., in the case of NR-DC, the timer T304 for the NR PSCell is not running, or in NE-DC, the timer T307 for the E-UTRA PSCell is not running):

[0253] 6> Initiate the MCG failure information procedure to report the MCG radio link failure.

[0254] 5> Otherwise:

[0255] 6> Initiate the connection reestablishment procedure.

[0256] The L2 / L3 U2N relay UE shall:

[0257] 1> When detecting a radio link failure:

[0258] 2> It indicates to the upper layer (to trigger the PC5 unicast link release) or sends a notification message to the connected L2 / L3 U2N remote UE.

[0259] The UE shall:

[0260] 1> When the T310 in the PSCell expires; or

[0261] 1> When the T312 in the PSCell expires; or

[0262] 1> When there is a random access problem indication from the SCG MAC; or

[0263] 1> When there is an indication from the SCG RLC that the maximum retransmission count has been reached; or

[0264] 1> If connected as an IAB node, when receiving a BH RLF indication from the SCG on the BAP entity; or

[0265] 1> When there is a consistent uplink LBT failure indication from the SCG MAC:

[0266] 2> If the indication is from the SCG RLC and CA duplication is configured and active for the SCG, and for the corresponding logical channel, allowedServingCells includes only SCell:

[0267] 3> Initiate a failure information procedure to report the RLC failure.

[0268] 2> Otherwise:

[0269] 3> Consider that a radio link failure is detected for the SCG (i.e., SCG RLF);

[0270] 3> If MCG transmission is not paused:

[0271] 4> Initiate an SCG failure information procedure to report the SCG radio link failure.

[0272] 3> Otherwise:

[0273] 4> If the UE is in NR-DC:

[0274] 5> Initiate a connection re-establishment procedure;

[0275] 4> Otherwise (the UE is in (NG)EN-DC):

[0276] 5> Initiate a connection re-establishment procedure;

[0277] In the following, the technical features related to the beam failure detection and recovery procedures are described. Reference can be made to Section 5.17 of 3GPP TS38.321 v17.0.0.

[0278] The MAC entity can configure the beam failure recovery procedure for each serving cell via RRC. This beam failure recovery procedure is used to indicate a new SSB or CSI-RS to the serving gNB when a beam failure is detected on the serving SSB / CSI-RS. Beam failure is detected by counting the beam failure instance indications from the lower layer to the MAC entity. If beamFailureRecoveryConfig is reconfigured by the upper layer during an ongoing random access procedure for beam failure recovery of the SpCell, the MAC entity shall stop the ongoing random access procedure and initiate a random access procedure with the new configuration.

[0279] RRC configures the following parameters for the beam failure detection and recovery procedures in BeamFailureRecoveryConfig, BeamFailureRecoverySCellConfig, BeamFailureRecoveryServingCellConfig, and RadioLinkMonitoringConfig:

[0280] - beamFailureInstanceMaxCount for beam failure detection (for each serving cell or each BFD-RS set of a serving cell configured with two BFD-RS sets);

[0281] - beamFailureDetectionTimer for beam failure detection (for each serving cell or each BFD-RS set of a serving cell configured with two BFD-RS sets);

[0282] - beamFailureRecoveryTimer for beam failure recovery process;

[0283] - rsrp-ThresholdSSB: RSRP threshold for SpCell beam failure recovery;

[0284] - rsrp-ThresholdBFR: RSRP threshold for SCell beam failure recovery or for beam failure recovery of the BFD-RS set of a serving cell;

[0285] - powerRampingStep: powerRampingStep for SpCell beam failure recovery;

[0286] - powerRampingStepHighPriority: powerRampingStepHighPriority for SpCell beam failure recovery;

[0287] - preambleReceivedTargetPower: preambleReceivedTargetPower for SpCell beam failure recovery;

[0288] - preambleTransMax: preambleTransMax for SpCell beam failure recovery;

[0289] - scalingFactorBI: ssb-perRACH-Occasion for SpCell beam failure recovery;

[0290] - ssb-perRACH-Occasion: ssb-perRACH-Occasion for SpCell beam failure recovery using contention-free random access resources;

[0291] -ra-ResponseWindow: A time window used to monitor responses for SpCell beam failure recovery using contention-free random access resources;

[0292] -prach-ConfigurationIndex: The prach-ConfigurationIndex for SpCell beam failure recovery using contention-free random access resources;

[0293] -ra-ssb-OccasionMaskIndex: The ra-ssb-OccasionMaskIndex for SpCell beam failure recovery using contention-free random access resources;

[0294] -ra-OccasionList: The ra-OccasionList for SpCell beam failure recovery using contention-free random access resources;

[0295] -candidateBeamRSList: A list of candidate beams for SpCell beam failure recovery;

[0296] -candidateBeamRSSCellList: A list of candidate beams for SCell beam failure recovery;

[0297] -candidateBeamresourceList: A list of candidate beams for beam failure recovery of BFD-RS set 0 of the serving cell;

[0298] -candidateBeamresourceList2: A list of candidate beams for beam failure recovery of BFD-RS set 1 of the serving cell.

[0299] The following UE variables are used in the beam failure detection process:

[0300] -BFI_COUNTER (for each serving cell or each BFD-RS set of a serving cell configured with two BFD-RS sets): A counter for beam failure instance indication initially set to 0.

[0301] When transmitting a MAC PDU and the PDU includes a BFR MAC CE or a truncated BFR MAC CE that contains beam failure information for the SCell, all BFRs triggered for the SCell shall be cancelled. When transmitting a MAC PDU and the PDU includes an enhanced BFR MAC CE or a truncated enhanced BFR MAC CE that contains beam failure recovery information for the BFD-RS set of the serving cell, all BFRs triggered for the BFD-RS set of the serving cell shall be cancelled.

[0302] In the following, technical features related to conditional handover are described. Reference can be made to Section 9.2.3.4 of 3GPP TS 38.300 v17.0.0.

[0303] Conditional handover (CHO) is defined as a handover performed by the UE when one or more handover execution conditions are met. The UE starts evaluating the execution conditions upon receiving the CHO configuration and stops evaluating the execution conditions once the handover is executed.

[0304] The following principles apply to CHO:

[0305] - The CHO configuration contains the configuration of CHO candidate cells generated by the candidate gNB and the execution conditions generated by the source gNB.

[0306] - The execution conditions can consist of one or two trigger conditions (CHO events A3 / A5). Only a single RS type is supported, and up to two different trigger quantities (e.g., RSRP and RSRQ, RSRP and SINR, etc.) can be configured simultaneously for evaluating the CHO execution conditions of a single candidate cell.

[0307] - Before any CHO execution condition is met, upon receiving a HO command (without CHO configuration), the UE performs the HO procedure regardless of any previously received CHO configuration.

[0308] - When performing CHO, i.e., starting from the time when the UE starts synchronizing with the target cell, the UE does not monitor the source cell.

[0309] CHO is also supported for IAB-MT in the cases of intra- and inter-donor IAB-node migration and BH RLF recovery.

[0310] In this version of the specification, CHO is not supported for NG-C-based handovers.

[0311] - C-plane processing

[0312] In NR intra-RAN handover, in NR intra-RAN CHO, the preparation and execution phases of the conditional handover procedure are performed without involving the 5GC; that is, the preparation messages are directly exchanged between gNBs. The release of resources at the source gNB during the conditional handover completion phase is triggered by the target gNB.

[0313] Figure 10a and Figure 10b shows an example of conditional handover within the AMF / UPF

[0314] Specifically, the following Figure 10a and Figure 10b depict a basic conditional handover scenario where neither the AMF nor the UPF changes.

[0315] 0. The UE context within the source gNB contains information on roaming and access restrictions provided at connection establishment or during the last TA update.

[0316] 1. The source gNB configures the UE measurement procedure and UE reporting according to the measurement configuration.

[0317] 2. The source gNB decides to use CHO.

[0318] 3. The source gNB requests CHO for one or more candidate cells belonging to one or more candidate gNBs. A CHO request message is sent for each candidate cell.

[0319] 4. Admission control can be performed by the target gNB. If slice information is sent to the target gNB, slice-aware admission control shall be performed. If the PDU session is associated with an unsupported slice, the target gNB shall reject such a PDU session.

[0320] 5. The candidate gNBs send a CHO response (HO request confirmation) including the configuration of the CHO candidate cells to the source gNB. A CHO response message is sent for each candidate cell.

[0321] 6. The source gNB sends an RRCReconfiguration message to the UE, which contains the configuration of the CHO candidate cells and the CHO execution conditions.

[0322] - The CHO configuration of the candidate cell can be followed by other reconfigurations from the source gNB.

[0323] - The configuration of the CHO candidate cell cannot contain DAPS handover configuration.

[0324] 7. The UE sends an RRCReconfigurationComplete message to the source gNB.

[0325] 7a. If early data forwarding is applied, the source gNB sends an EARLY STATUS TRANSFER message.

[0326] 8. After receiving the CHO configuration, the UE maintains the connection with the source gNB and starts to evaluate the CHO execution conditions for the candidate cells. If at least one CHO candidate cell meets the corresponding CHO execution conditions, the UE detaches from the source gNB, applies the corresponding configuration stored for the selected candidate cell, synchronizes to the candidate cell, and completes the RRC handover procedure by sending an RRCReconfigurationComplete message to the target gNB. The UE releases the stored CHO configuration after successfully completing the RRC handover procedure.

[0327] 8a / b. The target gNB sends a HANDOVER SUCCESS message to the source gNB to notify that the UE has successfully accessed the target cell. In return, the source gNB sends an SN STATUS TRANSFER message following the principle described in step 7 of the handover within AMF / UPF.

[0328] Once the source gNB receives the handover success message, it can initiate late data forwarding.

[0329] 8c. The source gNB sends a HANDOVER CANCEL message to other signaling connections or other candidate target gNBs (if any) to cancel the CHO for the UE.

[0330] - U-plane handling

[0331] If early data forwarding is applied, the U-plane handling for conditional handover follows the same principle as that for DAPS handover. Additionally, in the fully configured case, after handing over the SN assignment to the target gNB, the HFN and PDCP SN are reset in the target gNB. If late data forwarding is applied, the U-plane handling follows the RLC-AM or RLC-UM bearer principle.

[0332] - Data forwarding

[0333] If late data forwarding is applied, the source NG-RAN node initiates data forwarding once it knows which target NG-RAN node the UE has successfully accessed. In this case, the behavior of conditional handover data forwarding follows the same behavior as that for in-system handover data forwarding, except for the behavior of the DRB configured with DAPS handover.

[0334] If early data forwarding is applied instead, the source NG-RAN node forwards data to a concerned candidate target node before the UE performs a handover. The behavior of early data forwarding for conditional handover follows the same principle as that of the DRB configured with DAPS handover in intra-system handovers.

[0335] Meanwhile, when a beam failure is detected on the PCell, the UE performs a random access procedure for beam failure recovery. While performing the RA procedure, the uplink transmission and downlink reception are suspended. When a radio link failure is detected, the UE performs an RRC reconstruction procedure, and it also requires the UE to perform an RA procedure.

[0336] If the UE has the full configuration of a cell (i.e., a candidate serving cell that has been prepared for potential connection) and knows the exact uplink transmission timing, the candidate serving cell can be used by the UE for communication when the communication with the serving cell is unavailable for various reasons.

[0337] For example, when the serving cell is unavailable due to beam failure or RLF or other failure reasons, if the UE performs a self-organized cell handover from the serving cell to one of the candidate cells with known UL timing, the UE can continue to perform uplink transmission and downlink reception using the candidate serving cell even without performing the RA procedure.

[0338] Therefore, it is necessary to study self-organized serving cell handover in a wireless communication system.

[0339] Hereinafter, a method for self-organized serving cell handover in a wireless communication system according to some embodiments of the present disclosure will be described with reference to the following drawings.

[0340] The following drawings are created to explain specific embodiments of the present disclosure. The names of specific devices shown in the drawings or the names of specific signals / messages / fields are provided by way of example, so the technical features of the present disclosure are not limited to the specific names used in the following drawings. Herein, a wireless device may be referred to as a user equipment (UE).

[0341] Figure 11 An example of a method for self-organized serving cell handover in a wireless communication system according to some embodiments of the present disclosure is shown.

[0342] Specifically, Figure 11 An example of a method performed by a wireless device in a wireless communication system is shown.

[0343] In step S1101, the wireless device may configure a connection with the serving cell.

[0344] For example, the serving cell is a primary cell (PCell), a primary-secondary cell group (SCG) cell (PSCell), or a secondary cell (SCell).

[0345] For example, the wireless device may receive the configuration of the serving cell from the network.

[0346] In step S1102, the wireless device may receive the configuration for one or more candidate serving cells.

[0347] For example, the wireless device may be configured with one or more candidate serving cells.

[0348] For example, the wireless device may receive the pre-configuration of one or more candidate serving cells.

[0349] In step S1103, the wireless device may obtain the uplink transmission timing for at least one of the one or more candidate serving cells.

[0350] For example, the uplink transmission timing for at least one candidate serving cell may be obtained by performing a random access procedure with at least one candidate serving cell.

[0351] For example, the uplink transmission timing for at least one candidate serving cell may be obtained by calculating the uplink transmission timing based on the information received from the network. For example, the information received from the network may include information about (i) the uplink transmission timing difference between the serving cell and at least one candidate serving cell or (ii) the absolute uplink transmission timing of at least one candidate serving cell.

[0352] For example, the uplink transmission timing for at least one candidate serving cell may be obtained by sending a UL signal and receiving a UL timing update.

[0353] In step S1104, the wireless device may detect a failure related to the serving cell.

[0354] For example, the wireless device may perform radio link monitoring and / or beam failure detection for the serving cell. The wireless device may detect a failure related to the serving cell through radio link monitoring and / or beam failure detection.

[0355] For example, the failure related to the serving cell may include beam failure, radio link failure, handover failure, and / or compliance failure.

[0356] For example, a failure related to the serving cell can be detected by the Medium Access Control (MAC) layer of the wireless device. The MAC layer can notify the Radio Resource Control (RRC) layer of the wireless device about information on a specific candidate serving cell based on the MAC layer knowing the uplink transmission timing for the specific candidate serving cell.

[0357] In step S1105, the wireless device can select a specific candidate serving cell among at least one candidate serving cell for which the uplink transmission timing has been obtained.

[0358] For example, the specific candidate serving cell is selected based on the uplink transmission timing for the specific candidate serving cell being valid. That is, if there is a first candidate serving cell for which the uplink transmission timing has been obtained and a second candidate serving cell for which the uplink transmission timing has not been obtained, the wireless device can select the first candidate serving cell.

[0359] For example, the wireless device can start a timer when obtaining the uplink transmission timing for a specific candidate serving cell. When the timer is running, the wireless device can consider the uplink transmission timing for the specific candidate serving cell to be valid.

[0360] In step S1106, the wireless device can perform a serving cell handover from the serving cell to the specific candidate serving cell based on the configuration for the specific candidate serving cell.

[0361] For example, the wireless device can perform an uplink transmission to the specific candidate serving cell without a random access procedure. That is, since the wireless device knows the uplink transmission timing, the wireless device can perform an uplink transmission to the specific candidate serving cell without having to perform a random access procedure in advance.

[0362] According to some embodiments of the present disclosure, the wireless device can receive a configuration on a candidate serving cell. The wireless device can detect a serving beam / serving cell failure on the serving cell. If the wireless device has a valid uplink transmission timing for a candidate serving cell associated with the serving cell, the wireless device can use the candidate serving cell to perform a serving cell handover.

[0363] Hereinafter, technical features related to autonomous serving cell handover are described.

[0364] For example, new conditions for autonomous cell handover can be used in the present disclosure.

[0365] The UE is configured with at least one serving cell. The UE is configured with at least one candidate serving cell. The candidate serving cell can be associated with a certain serving cell.

[0366] When a beam / failure of a serving cell is detected, if the UE knows the uplink transmission timing of a candidate serving cell associated with the serving cell, the UE autonomously performs a serving cell handover from the serving cell where the beam / serving cell failure is detected to the candidate serving cell.

[0367] When a beam failure is detected on a serving cell, if the UE does not know the uplink transmission timing of a candidate serving cell associated with the serving cell, the UE performs a beam failure reporting procedure or a random access procedure. When a serving cell failure is detected on a serving cell, if the UE does not know the uplink transmission timing of a candidate serving cell associated with the serving cell, the UE performs an RRC reconstruction procedure.

[0368] A candidate serving cell may be associated with a certain serving cell type (i.e., a PCell, a PSCell, or an SCell). When a beam / serving cell failure is detected for a serving cell, if the UE knows the uplink transmission timing of a candidate serving cell associated with the serving cell type of the serving cell, the UE performs a serving cell handover from the serving cell where the beam / serving cell failure is detected to the candidate serving cell.

[0369] Figure 12 An example of a procedure for autonomous serving cell handover is shown.

[0370] In step S1201, the UE is configured with at least one serving cell.

[0371] For example, the UE may receive the configuration of at least one serving cell.

[0372] The serving cell is a PCell, a PSCell, or an SCell.

[0373] In step S1202, the UE may receive the pre-configuration of a candidate serving cell.

[0374] The UE is configured with at least one serving cell. The UE is configured with at least one candidate serving cell for mobility.

[0375] For example, the UE may receive the pre-configuration of a candidate serving cell.

[0376] If the UE receives the configuration on a candidate serving cell, the UE stores the configuration but does not apply it. When the candidate serving cell becomes a serving cell, the UE applies the configuration of the candidate serving cell. If the network provides a command for cell handover from a serving cell to a candidate cell, the candidate serving cell may become a serving cell.

[0377] In step S1203, the UE may perform UL timing management for the candidate cell.

[0378] The configuration for a candidate serving cell includes resources and parameters for uplink timing control of the candidate serving cell. While the UE is connected to the serving cell, the UE can perform uplink timing acquisition for the candidate serving cell.

[0379] The UE can obtain the uplink transmission timing of the candidate serving cell by performing a random access procedure with the candidate serving cell. Alternatively, the UE can use the information received from the network (e.g., the uplink transmission timing difference between the serving cell and the candidate serving cell or the absolute uplink transmission timing of the candidate serving cell) to calculate the uplink transmission timing of the candidate serving cell. Once the UE obtains the UL timing information via random access or the transmission of UL signals and the reception of UL timing updates, the UE can consider the obtained UL timing to be valid until a certain period of time. This period of time can be managed by a timer, where the timer is started at the initial acquisition of UL timing or the update of UL timing. The UE considers the UL timing to be valid until the timer runs. When the timer expires, the UE considers the UL timing to be invalid.

[0380] In step S1204, the UE can perform link monitoring of the serving cell and recovery from link failure.

[0381] The UE performs wireless link monitoring and / or beam failure detection of the serving cell. When a beam failure or radio link failure of the serving cell is detected, if the UE knows the uplink transmission timing of the candidate serving cell, the UE performs a self-organized cell handover from the serving cell where the beam / serving cell failure is detected to the candidate serving cell, and if the UE does not know the uplink transmission timing of any candidate cell, the UE does not perform a serving cell handover but performs a reconstruction when fast MCG recovery is not configured or DC is not configured for the UE.

[0382] When a self-organized cell handover is triggered, if the UE knows the uplink transmission timing of the candidate serving cell, the UE hands over the serving cell to the candidate serving cell.

[0383] When a beam / serving cell failure is detected, a self-organized cell handover is triggered.

[0384] When a self-organized cell handover is triggered, if the UE knows the uplink transmission timing of more than one candidate serving cell, the UE can select one candidate serving cell with available uplink transmission timing among the candidate serving cells and perform a cell handover using the selected candidate serving cell. For example, when an RLF is detected on the PCell, two candidate serving cells are configured for the UE, namely, candidate serving cell A and B. At this time, the UE knows the UL timing of cell A but does not know the UL timing of cell B. Then, the UE changes the PCell from the current PCell to candidate serving cell A.

[0385] If a serving cell handover is triggered for the serving cell, the UE regards the current serving cell as a candidate serving cell and stores the configuration of the serving cell. Alternatively, if a serving cell handover is triggered, the UE discards the configuration of the serving cell. If a serving cell handover is triggered, the UE regards the target candidate serving cell as the serving cell and applies the configuration of the target candidate serving cell.

[0386] The terms used in this disclosure are as follows.

[0387] Recovery from beam failure: When a beam failure is detected on the SCell, the UE does not perform a serving cell handover and performs a BFR procedure. When a beam failure is detected on the SpCell, if the UE knows the uplink transmission timing of the candidate serving cell, the UE performs a SpCell handover from the SpCell where the beam failure is detected to the candidate serving cell.

[0388] Recovery from RLF: If a radio link failure is detected for the serving cell, the UE may consider that a serving cell failure is detected.

[0389] Recovery from handover failure: If the SpCell change (i.e., mobility with synchronization) fails, the UE may consider that a serving cell failure is detected.

[0390] Recovery from compliance failure: If the UE cannot comply with the (partial) configuration included in the RRCReconfiguration message, the UE may consider that a serving cell failure is detected.

[0391] Figure 13 An example of a method for autonomous serving cell handover performed by the UE is shown.

[0392] In step 1301, the UE receives the configuration on the candidate serving cell.

[0393] The configuration includes all the information for the candidate serving cell to be used as the serving cell. When receiving this configuration, the UE stores the configuration but does not apply the configuration (i.e., the UE does not regard the candidate serving cell as the serving cell).

[0394] After receiving the configuration, the UE may perform a RA procedure to obtain the uplink transmission timing of the candidate serving cell. Otherwise, auxiliary information for obtaining the uplink transmission timing of the candidate serving cell (e.g., the uplink transmission timing difference between the serving cell and the candidate serving cell) may also be included in the configuration.

[0395] In step 1302, the UE detects a serving beam / serving cell failure on the serving cell.

[0396] In step 1303, if the UE has a valid uplink transmission timing of a candidate serving cell associated with the serving cell, the UE can use the candidate serving cell to perform a serving cell handover.

[0397] When a beam failure is detected and the MAC layer knows the uplink transmission timing of the candidate serving cell, the MAC layer notifies the RRC layer of the candidate serving cell identity. Then, the RRC layer initiates a serving cell handover using the candidate serving cell indicated by the MAC layer.

[0398] If the UE knows the uplink transmission timing of more than one candidate serving cell, the UE can select one based on the quality of the candidate serving cell (e.g., DL measurement results).

[0399] In the following, technical features related to autonomous serving cell handover implementing the present disclosure are described. In particular, operations related to LTM configuration and execution are described.

[0400] The network configures the UE with one or more LTM candidate configurations within the LTM-Config IE.

[0401] In NR-DC, the UE can receive two independent ltm-Configs:

[0402] - The ltm-Config associated with the MCG included in the RRCReconfiguration message received via SRB1; and

[0403] - The ltm-Config associated with the SCG included in the RRCReconfiguration message received via SRB3 (alternatively, embedded in the RRCReconfiguration message received via SRB1).

[0404] In this case:

[0405] - The UE maintains two independent VarLTM-Configs, one associated with each ltm-Config;

[0406] - The UE maintains two independent VarLTM-ServingCellNoResetID, one associated with each ltm-Config;

[0407] - The UE maintains two independent VarLTM-ServingCellUE-MeasuredTA-ID, one associated with each ltm-Config;

[0408] - The UE independently performs all procedures for each ltm-Config and the associated VarLTM-Config, unless otherwise explicitly specified.

[0409] The UE shall perform the following actions based on the received LTM-Config IE:

[0410] 1> If the received LTM-Config includes ltm-ReferenceConfiguration:

[0411] 2> If the current VarLTM-Config includes ltm-ReferenceConfiguration:

[0412] 3> Replace the ltm-ReferenceConfiguration value within the VarLTM-Config with the received ltm-ReferenceConfiguration;

[0413] 2> Otherwise:

[0414] 3> Store the received ltm-ReferenceConfiguration into the VarLTM-Config;

[0415] 1> If the received LTM-Config includes ltm-ServingCellNoResetID:

[0416] 2> If the current VarLTM-ServingCellNoResetID includes ltm-ServingCellNoResetID:

[0417] 3> Replace the ltm-ServingCellNoResetID value within the VarLTM-ServingCellNoResetID with the received ltm-ServingCellNoResetID;

[0418] 2> Otherwise:

[0419] 3> Store the received ltm-ServingCellNoResetID into the VarLTM-ServingCellNoResetID;

[0420] 1> If the received LTM-Config includes ltm-ServingCellUE-MeasuredTA-ID:

[0421] 2> If the current VarLTM-ServingCellUE-MeasuredTA-ID includes ltm-ServingCellUE-MeasuredTA-ID:

[0422] 3> Replace the ltm-ServingCellUE-MeasuredTA-ID value within VarLTM-ServingCellUE-MeasuredTA-ID with the received ltm-ServingCellUE-MeasuredTA-ID;

[0423] 2> Otherwise:

[0424] 3> Store the received ltm-ServingCellUE-MeasuredTA-ID into VarLTM-ServingCellUE-MeasuredTA-ID;

[0425] 1> If the received LTM-Config includes ltm-CSI-ResourceConfigToAddModList:

[0426] 2> If the current VarLTM-Config includes ltm-CSI-ResourceConfigToAddModList:

[0427] 3> Replace the ltm-CSI-ResourceConfigToAddModList value within VarLTM-Config with the received ltm-CSI-ResourceConfigToAddModList;

[0428] 2> Otherwise:

[0429] 3> Store the received ltm-CSI-ResourceConfigToAddModList into VarLTM-Config;

[0430] 1> If LTM-Config includes ltm-CandidateToReleaseList:

[0431] 2> Perform LTM candidate configuration release;

[0432] 1> Otherwise, if the received LTM-Config includes ltm-CandidateToAddModList:

[0433] 2> Perform LTM candidate cell addition or reconfiguration;

[0434] Describes operations related to the release of LTM candidate configurations.

[0435] The UE shall:

[0436] 1> For each ltm-CandidateId value included in the ltm-CandidateToReleaseList that is part of the current UE LTM candidate configuration in VarLTM-Config:

[0437] 2> If the current VarLTM-Config includes an LTM-Candidate associated with the given ltm-CandidateId value:

[0438] 3> Remove the entry related to the LTM-Candidate from VarLTM-Config;

[0439] Describes operations related to the addition / modification of LTM candidate cells.

[0440] The UE shall:

[0441] 1> For each ltm-CandidateId value in the ltm-CandidateToAddModList:

[0442] 2> If the current VarLTM-Config includes an LTM-Candidate with the given ltm-CandidateId value:

[0443] 3> Replace the LTM-Candidate within VarLTM-Config according to the received LTM-Candidate;

[0444] 2> Otherwise:

[0445] 3> Add the received LTM-Candidate to VarLTM-Config.

[0446] Describes operations related to the execution of LTM cell handover.

[0447] When the lower layer indicates that the LTM cell handover process is triggered, or when performing LTM cell handover after cell selection while timer T311 is running, the UE shall:

[0448] 1> Release / clear all current dedicated radio configurations associated with the cell group that triggered the LTM cell handover process, except for the following cases:

[0449] 2> If the LTM cell handover is triggered on the MCG:

[0450] - MCG C-RNTI;

[0451] - AS security configuration associated with the master key;

[0452] 2> Otherwise, if an LTM cell handover is triggered on the SCG:

[0453] - AS security configuration associated with the secondary key;

[0454] 2> For each SRB / DRB in the current UE configuration:

[0455] - Retain the associated PDCP and SDAP entities, their state variables, buffers, and timers;

[0456] - Release all fields related to the SRB / DRB configuration except srb-Identity and drb-Identity;

[0457] 2> For each RLC bearer in the current UE configuration of the cell group that triggers LTM:

[0458] - Retain the associated RLC entity, its state variables, buffers, and timers;

[0459] - Release all fields related to RLC-BearerConfig except logicalChannelIdentity and logicalChannelIdentityExt.

[0460] - UE variables VarLTM-Config and VarLTM-ServingCellNoResetID.

[0461] During an LTM cell handover, the UE shall release radio bearers and associated logical channels that are part of the current UE configuration but not part of the LTM candidate configuration indicated by the lower layer or the LTM reference configuration.

[0462] 1> Release / clear all current common radio configurations associated with the cell group that triggered the LTM cell handover procedure;

[0463] 1> Use the default values of timers T310, T311 and constants N310, N311 associated with the cell group that triggered the LTM cell handover procedure;

[0464] 1> Apply the default L1 parameter values as specified in the corresponding physical layer specification;

[0465] 1> If the value of the ltm-NoResetID field contained within the LTM-Candidate IE in VarLTM-Config indicated by the lower layer or for the selected cell is equal to the value of ltm-ServingCellNoResetID within VarLTM-ServingCellNoResetID:

[0466] 2> Continue to use the current RLC entity in the LTM candidate configuration indicated by the lower layer;

[0467] 2> Replace the value of ltm-ServingCellNoResetID in VarLTM-ServingCellNoResetID with the value received within ltm-NoResetID;

[0468] 1> Otherwise:

[0469] 2> For each RLC-BearerConfig within rlc-BearerToAddModList that is part of the current UE configuration:

[0470] 3> Re-establish the RLC entity;

[0471] 2> For each drb-Identity value included in drb-ToAddModList that is part of the current UE configuration:

[0472] 3> Trigger the PDCP entity of the DRB to perform data recovery;

[0473] 2> Replace the value of ltm-ServingCellNoResetID in VarLTM-ServingCellNoResetID with the value of ltm-NoResetID in the LTM-Candidate within VarLTM-Config indicated by the lower layer or for the selected cell;

[0474] 1> If the value of the ltm-UE-MeasuredTA-ID field contained within the LTM-Candidate IE in VarLTM-Config indicated by the lower layer or for the selected cell is equal to the value of ltm-ServingCellUE-MeasuredTA-ID within VarLTM-ServingCellUE-MeasuredTA-ID:

[0475] 2> Notify the lower layer that the UE should perform UE-based TA measurement;

[0476] 2> Replace the value of ltm-ServingCellUE-MeasuredTA-ID in VarLTM-ServingCellUE-MeasuredTA-ID with the value received within ltm-UE-MeasuredTA-ID;

[0477] 1> Otherwise:

[0478] 2> Replace the value of ltm-ServingCellUE-MeasuredTA-ID in VarLTM-ServingCellUE-MeasuredTA-ID with the value of ltm-UE-MeasuredTA-ID in LTM-Candidate within VarLTM-Config indicated by the lower layer or for the selected cell;

[0479] 1> Continue to use the current PDCP entity in the LTM candidate configuration indicated by the lower layer; 1> If ltm-ConfigComplete is not included within the LTM-Candidate IE in VarLTM-Config indicated by the lower layer or for the selected cell:

[0480] 2> Consider ltm-ReferenceConfiguration in VarLTM-Config as the current UE configuration.

[0481] When the UE considers the reference configuration as the current UE configuration, the UE shall store the fields and configurations that are part of the reference configuration, but shall not perform any actions or procedures triggered by receiving an RRCReconfiguration message.

[0482] 1> If an LTM cell handover is triggered by an indication from the lower layer:

[0483] 2> Apply the LTM configuration in ltm-CandidateConfig within the LTM-Candidate IE in VarLTM-Config related to the LTM candidate configuration identity received from the lower layer;

[0484] 1> Otherwise (LTM cell handover is triggered during cell selection while timer T311 is running):

[0485] 2> While timer T311 is running, apply the LTM configuration in ltm-CandidateConfig within the LTM-Candidate IE in VarLTM-Config related to the LTM candidate configuration identity corresponding to the selected cell;

[0486] 2>Execute the LTM configuration release process for MCG.

[0487] Before triggering the execution of LTM cell handover in the lower layer, applying the LTM candidate configuration on top of the LTM reference configuration depends on the UE implementation.

[0488] Operations related to LTM configuration release are described.

[0489] For the cell group that triggers the LTM configuration release process, the UE shall:

[0490] 1> Remove all entries in VarLTM-Config;

[0491] 1> Remove all entries in VarLTM-ServingCellNoResetID;

[0492] 1> Remove all entries in VarLTM-ServingCellUE-MeasuredTA-ID;

[0493] 1> Release ltm-Config;

[0494] 1> Release all entries of ltm-CSI-ReportConfigToAddModList for all serving cells from the current UE configuration.

[0495] In Figure 11 、 Figure 12 and Figure 13 Some of the detailed steps shown in the examples may not be necessary steps and can be omitted. Except for Figure 11 、 12 and the steps shown in 13, other steps can be added and the order of the steps can vary. Some of the above steps may have their own technical meanings.

[0496] Hereinafter, devices for autonomous serving cell handover in a wireless communication system according to some embodiments of the present disclosure will be described. Here, the device can be the Figure 2 、 Figure 3 and Figure 5 wireless device (100 or 200) in.

[0497] For example, the wireless device can execute the above method. Detailed descriptions overlapping with the above can be simplified or omitted.

[0498] Referring to Figure 5 , the wireless device 100 can include a processor 102, a memory 104, and a transceiver 106.

[0499] According to some embodiments of the present disclosure, the processor 102 may be configured to be operatively coupled to the memory 104 and the transceiver 106.

[0500] The processor 102 may be adapted to configure a connection to a serving cell. The processor 102 may be adapted to receive a configuration for one or more candidate serving cells. The processor 102 may be adapted to obtain an uplink transmission timing of at least one candidate serving cell among one or more candidate serving cells. The processor 102 may be adapted to detect a failure related to the serving cell. The processor 102 may be adapted to select a specific candidate serving cell among the at least one candidate serving cell for which the uplink transmission timing has been obtained. The processor 102 may be adapted to perform a serving cell handover from the serving cell to the specific candidate serving cell based on the configuration for the specific candidate serving cell.

[0501] For example, the specific candidate serving cell may be selected based on the uplink transmission timing for the specific candidate serving cell being valid.

[0502] For example, the processor 102 may be adapted to start a timer when obtaining the uplink transmission timing for a specific candidate serving cell.

[0503] For example, the processor 102 may be adapted to consider the uplink transmission timing of the specific candidate serving cell as valid when the timer is running.

[0504] For example, the processor 102 may be adapted to perform radio link monitoring and / or beam failure detection for the serving cell.

[0505] For example, the processor 102 may be adapted to perform an uplink transmission to a specific candidate serving cell without a random access procedure.

[0506] For example, the serving cell may be a primary cell (PCell), a primary-secondary cell group (SCG) cell (PSCell), or a secondary cell (SCell).

[0507] For example, the processor 102 may be adapted to receive a configuration of the serving cell.

[0508] For example, the failure related to the serving cell may include a beam failure, a radio link failure, a handover failure, and / or a compliance failure.

[0509] For example, the failure related to the serving cell may be detected by the media access control (MAC) layer of the wireless device.

[0510] For example, the processor 102 may be adapted to know the uplink transmission timing for a specific candidate serving cell based on the MAC layer, and the MAC layer may notify information about the specific candidate serving cell to the radio resource control (RRC) layer of the wireless device.

[0511] For example, the uplink transmission timing for at least one candidate serving cell can be obtained by performing a random access procedure with at least one candidate serving cell.

[0512] For example, the uplink transmission timing for at least one candidate serving cell can be obtained by calculating the uplink transmission timing based on information received from the network.

[0513] For example, the processor 102 can be adapted to control the transceiver 106 to communicate with at least one of a user equipment, a network, or an autonomous vehicle other than the wireless device.

[0514] Hereinafter, a processor of a wireless device for autonomous serving cell handover in a wireless communication system according to some embodiments of the present disclosure will be described.

[0515] The processor can be adapted to control the wireless device to configure a connection with a serving cell. The processor can be adapted to control the wireless device to receive a configuration for one or more candidate serving cells. The processor can be adapted to control the wireless device to obtain the uplink transmission timing for at least one candidate serving cell among one or more candidate serving cells. The processor can be adapted to control the wireless device to detect a failure related to the serving cell. The processor can be adapted to control the wireless device to select a specific candidate serving cell among the at least one candidate serving cell for which the uplink transmission timing has been obtained. The processor can be adapted to control the wireless device to perform a serving cell handover from the serving cell to the specific candidate serving cell based on the configuration for the specific candidate serving cell.

[0516] For example, the specific candidate serving cell can be selected based on the uplink transmission timing for the specific candidate serving cell being valid.

[0517] For example, the processor can be adapted to control the wireless device to start a timer when obtaining the uplink transmission timing for a specific candidate serving cell.

[0518] For example, the processor can be adapted to control the wireless device to consider the uplink transmission timing for a specific candidate serving cell to be valid while the timer is running.

[0519] For example, the processor can be adapted to control the wireless device to perform radio link monitoring and / or beam failure detection for the serving cell.

[0520] For example, the processor can be adapted to control the wireless device to perform an uplink transmission to a specific candidate serving cell without a random access procedure.

[0521] For example, the serving cell may be a primary cell (PCell), a primary-secondary cell group (SCG) cell (PSCell), or a secondary cell (SCell).

[0522] For example, the processor may be adapted to control the wireless device to receive the configuration of the serving cell.

[0523] For example, the failures related to the serving cell may include beam failure, radio link failure, handover failure, and / or compliance failure.

[0524] For example, the failures related to the serving cell may be detected by the media access control (MAC) layer of the wireless device.

[0525] For example, the processor may be adapted to control the wireless device to know the uplink transmission timing for a specific candidate serving cell based on the MAC layer, and the MAC layer notifies the radio resource control (RRC) layer of the wireless device about the information of the specific candidate serving cell.

[0526] For example, the uplink transmission timing for at least one candidate serving cell may be obtained by performing a random access procedure with at least one candidate serving cell.

[0527] For example, the uplink transmission timing for at least one candidate serving cell may be obtained by calculating the uplink transmission timing based on the information received from the network.

[0528] For example, the processor may be configured to control the wireless device to communicate with at least one of a user equipment, a network, or an autonomous vehicle other than the wireless device.

[0529] Hereinafter, a non-transitory computer-readable medium storing a plurality of instructions for autonomous serving cell handover in a wireless communication system according to some embodiments of the present disclosure will be described.

[0530] According to some embodiments of the present disclosure, the technical features of the present disclosure may be directly implemented in hardware, in software executed by a processor, or in a combination of both. For example, the 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 a RAM memory, a flash memory, a ROM memory, an EPROM memory, an EEPROM memory, a register, a hard disk, a removable disk, a CD-ROM, or any other storage medium.

[0531] Some examples of the storage medium are coupled to the processor such that the processor can read information from the storage medium. In an alternative, the storage medium may be integrated into the processor. The processor and the storage medium may reside in an ASIC. For another example, the processor and the storage medium may reside as discrete components.

[0532] A computer-readable medium may include a tangible and non-transitory computer-readable storage medium.

[0533] For example, the non-transitory computer-readable medium may include a 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. The non-transitory computer-readable medium may also include a combination of the above.

[0534] In addition, the methods described herein may be implemented at least in part by a computer-readable communication medium that carries or conveys code in the form of instructions or data structures and can be accessed, read, and / or executed by a computer.

[0535] According to some embodiments of the present disclosure, a plurality of instructions are stored on a non-transitory computer-readable medium. The stored plurality of instructions may be executed by a processor of a wireless device.

[0536] The stored plurality of instructions may cause the wireless device to configure a connection to a serving cell. The stored plurality of instructions may cause the wireless device to receive configurations for one or more candidate serving cells. The stored plurality of instructions may cause the wireless device to obtain uplink transmission timing for at least one of the one or more candidate serving cells. The stored plurality of instructions may cause the wireless device to detect a failure related to the serving cell. The stored plurality of instructions may cause the wireless device to select a specific candidate serving cell among the at least one candidate serving cell for which uplink transmission timing has been obtained. The stored plurality of instructions may cause the wireless device to perform a serving cell handover from the serving cell to the specific candidate serving cell based on the configuration for the specific candidate serving cell.

[0537] For example, the specific candidate serving cell may be selected based on the uplink transmission timing for the specific candidate serving cell being valid.

[0538] For example, the stored plurality of instructions may cause the wireless device to start a timer when obtaining the uplink transmission timing for a specific candidate serving cell.

[0539] For example, the stored plurality of instructions may cause the wireless device to consider the uplink transmission timing for a specific candidate serving cell to be valid when the timer is running.

[0540] For example, the stored plurality of instructions may cause the wireless device to perform radio link monitoring and / or beam failure detection for the serving cell.

[0541] For example, the stored plurality of instructions may cause the wireless device to perform an uplink transmission to a specific candidate serving cell without a random access procedure.

[0542] For example, the serving cell may be a primary cell (PCell), a primary-secondary cell group (SCG) cell (PSCell), or a secondary cell (SCell).

[0543] For example, the stored plurality of instructions may cause the wireless device to receive a configuration of a serving cell.

[0544] For example, failures related to the serving cell may include beam failure, radio link failure, handover failure, and / or compliance failure.

[0545] For example, failures related to the serving cell may be detected by the media access control (MAC) layer of the wireless device.

[0546] For example, the stored plurality of instructions may cause the wireless device to know, based on the MAC layer, the uplink transmission timing for a specific candidate serving cell, and the MAC layer may notify the radio resource control (RRC) layer of the wireless device about information regarding the specific candidate serving cell.

[0547] For example, the uplink transmission timing for at least one candidate serving cell may be obtained by performing a random access procedure with at least one candidate serving cell.

[0548] For example, the uplink transmission timing for at least one candidate serving cell may be obtained by calculating the uplink transmission timing based on information received from the network.

[0549] For example, the stored plurality of instructions may cause the wireless device to communicate with at least one of a user equipment, a network, or an autonomous vehicle other than the wireless device.

[0550] Hereinafter, a method for autonomous serving cell handover in a wireless communication system performed by a base station (BS) according to some embodiments of the present disclosure will be described.

[0551] The BS may send a configuration of a serving cell to the wireless device. The BS may send a pre-configuration for one or more candidate serving cells to the wireless device. The BS may send information about the uplink transmission timing for at least one of the one or more candidate serving cells to the wireless device. The BS may receive uplink data from the wireless device via the serving cell. The BS may receive uplink data from the wireless device via a specific candidate cell among the one or more candidate serving cells without a random access procedure.

[0552] In the following, a base station (BS) for autonomous serving cell handover in a wireless communication system according to some embodiments of the present disclosure will be described.

[0553] The BS may include a transceiver, a memory, and a processor operatively coupled to the transceiver and the memory.

[0554] The processor may be adapted to send a configuration of a serving cell to a wireless device. The processor may be adapted to send a pre-configuration for one or more candidate serving cells to the wireless device. The processor may be adapted to send information about an uplink transmission timing for at least one of the one or more candidate serving cells to the wireless device. The processor may be adapted to receive uplink data from the wireless device via the serving cell. The processor may be adapted to receive uplink data from the wireless device via a specific candidate cell among the one or more candidate serving cells without a random access procedure.

[0555] The present disclosure may have various advantageous effects.

[0556] According to some embodiments of the present disclosure, a wireless device may efficiently perform autonomous serving cell handover.

[0557] When the serving cell becomes unavailable due to beam failure or RLF, the UE may maintain uplink transmission and downlink reception using candidate serving cells even without performing an RA procedure.

[0558] In other words, by pre-acquiring the uplink transmission timing, the wireless device may efficiently perform autonomous serving cell handover.

[0559] According to some embodiments of the present disclosure, a wireless communication system may provide an efficient solution for autonomous serving cell handover.

[0560] For example, the network may efficiently provide a configuration of candidate serving cells and / or uplink transmission timing for autonomous serving cell handover.

[0561] The beneficial effects that can be obtained through specific embodiments of the present disclosure are not limited to the beneficial effects listed above. For example, there may be various technical effects that can be understood and / or deduced by those of ordinary skill in the relevant art from the present disclosure. 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 deduced from the technical features of the present disclosure.

[0562] The claims in this disclosure can be combined in various ways. For example, the technical features in the method claims of this disclosure can be combined to be implemented or executed in a device, and the technical features in the device claims can be combined to be implemented or executed in a method. In addition, the technical features in the method claims and the device claims can be combined to be implemented or executed in a device. In addition, the technical features in the method claims and the device claims can be combined to be implemented or executed in a method. Other implementations are within the scope of the appended claims.

Claims

1. A method performed by a wireless device in a wireless communication system, the method comprising: Configuring a connection to a serving cell; Receiving configurations for one or more candidate serving cells; Obtaining an uplink transmission timing for at least one of the one or more candidate serving cells; Detecting a failure related to the serving cell; Selecting a specific candidate serving cell among the at least one candidate serving cell for which the uplink transmission timing has been obtained; And Performing a serving cell handover from the serving cell to the specific candidate serving cell based on the configuration for the specific candidate serving cell.

2. The method according to claim 1, Among them, Selecting the specific candidate serving cell based on the uplink transmission timing for the specific candidate serving cell being valid.

3. The method according to claim 1, wherein, The method further comprises: Starting a timer when obtaining the uplink transmission timing for the specific candidate serving cell.

4. The method according to claim 3, wherein, The method further comprises: Considering the uplink transmission timing for the specific candidate serving cell as valid when the timer is running.

5. The method according to claim 1, wherein The method further comprises: Performing radio link monitoring and / or beam failure detection for the serving cell.

6. The method according to claim 1, wherein The method further comprises: Performing an uplink transmission to the specific candidate serving cell without a random access procedure.

7. The method according to claim 1, Among them, The serving cell is a primary cell (PCell), a primary cell in a primary secondary cell group (SCG) (PSCell), or a secondary cell (SCell).

8. The method according to claim 1, wherein The method further comprises: Receiving the configuration of the serving cell.

9. The method according to claim 1, Among them, The failure related to the serving cell includes beam failure, radio link failure, handover failure, and / or compliance failure.

10. The method according to claim 1, Among them, The failure related to the serving cell is detected by the media access control (MAC) layer of the wireless device.

11. The method according to claim 10, wherein, The method further comprises: Based on the MAC layer knowing the uplink transmission timing for the specific candidate serving cell, the MAC layer notifying the radio resource control (RRC) layer of the wireless device about information regarding the specific candidate serving cell.

12. The method according to claim 1, Among them, Obtaining the uplink transmission timing for the at least one candidate serving cell by performing a random access procedure with the at least one candidate serving cell.

13. The method according to claim 1, Among them, Obtaining the uplink transmission timing for the at least one candidate serving cell by calculating the uplink transmission timing based on information received from the network.

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

15. A wireless device in a wireless communication system, the wireless device comprising: A transceiver; A memory; And At least one processor, the at least one processor being operatively coupled to the transceiver and the memory and adapted to: Configure a connection to a serving cell; Receive configurations for one or more candidate serving cells; Obtain the uplink transmission timing for at least one candidate serving cell among the one or more candidate serving cells; Detect a failure related to the serving cell; Select a specific candidate serving cell among the at least one candidate serving cell for which the uplink transmission timing has been obtained; and Perform a serving cell handover from the serving cell to the specific candidate serving cell based on the configuration for the specific candidate serving cell.

16. The wireless device according to claim 15, Among them, Select the specific candidate serving cell based on the uplink transmission timing for the specific candidate serving cell being valid.

17. The wireless device according to claim 15, wherein, The at least one processor is further adapted to: Start a timer when obtaining the uplink transmission timing for the specific candidate serving cell.

18. The wireless device according to claim 17, wherein, The at least one processor is further adapted to: When the timer is running, consider the uplink transmission timing for the specific candidate serving cell to be valid.

19. The wireless device according to claim 15, wherein, The at least one processor is further adapted to: Perform radio link monitoring and / or beam failure detection for the serving cell.

20. The wireless device according to claim 15, wherein, The at least one processor is further adapted to: Perform an uplink transmission to the specific candidate serving cell without a random access procedure.

21. The wireless device according to claim 15, Among them, The serving cell is a primary cell (PCell), a primary secondary cell group (SCG) cell (PSCell), or a secondary cell (SCell).

22. The wireless device according to claim 15, wherein, The at least one processor is further adapted to: Receive the configuration of the serving cell.

23. The wireless device according to claim 15, Among them, The failure related to the serving cell includes beam failure, radio link failure, handover failure, and / or compliance failure.

24. The wireless device according to claim 15, Among them, The failure related to the serving cell is detected by the media access control (MAC) layer of the wireless device.

25. The wireless device according to claim 24, wherein, The at least one processor is further adapted to: Based on the MAC layer knowing the uplink transmission timing for the specific candidate serving cell, the MAC layer notifies the radio resource control (RRC) layer of the wireless device about information regarding the specific candidate serving cell.

26. The wireless device according to claim 15, Among them, Obtain the uplink transmission timing for the at least one candidate serving cell by performing a random access procedure with the at least one candidate serving cell.

27. The wireless device according to claim 15, Among them, Obtain the uplink transmission timing for the at least one candidate serving cell by calculating the uplink transmission timing based on information received from the network.

28. The wireless device according to claim 15, Among them, The wireless device communicates with at least one of a user equipment, a network, or an autonomous vehicle other than the wireless device.

29. A processor for a wireless device in a wireless communication system, wherein, The processor is configured to control the wireless device to perform operations, the operations including: Configure a connection with a serving cell; Receive configurations for one or more candidate serving cells; Obtain the uplink transmission timing for at least one of the one or more candidate serving cells; Detect a failure related to the serving cell; Select a specific candidate serving cell among the at least one candidate serving cell for which the uplink transmission timing has been obtained; and Perform a serving cell handover from the serving cell to the specific candidate serving cell based on the configuration for the specific candidate serving cell.

30. A non-transitory computer-readable medium storing a plurality of instructions, the plurality of instructions causing a wireless device to perform operations when executed by a processor of the wireless device, the operations including: Configure a connection to a serving cell; Receive configurations for one or more candidate serving cells; Obtain the uplink transmission timing for at least one of the one or more candidate serving cells; Detect a failure related to the serving cell; Select a specific candidate serving cell among the at least one candidate serving cell for which the uplink transmission timing has been obtained; And Perform a serving cell handover from the serving cell to the specific candidate serving cell based on the configuration for the specific candidate serving cell.

31. A method performed by a base station in a wireless communication system, the method including: Send a configuration of a serving cell to a wireless device; Send pre-configurations for one or more candidate serving cells to the wireless device; Send information about the uplink transmission timing for at least one of the one or more candidate serving cells to the wireless device; Receive uplink data from the wireless device via the serving cell; And Receive uplink data from the wireless device via a specific candidate cell among the one or more candidate serving cells without a random access procedure.

32. A base station in a wireless communication system, the base station including: A transceiver; A memory; And A processor, the processor being operatively coupled to the transceiver and the memory and adapted to: Send a configuration of a serving cell to a wireless device; Send pre-configurations for one or more candidate serving cells to the wireless device; Send information about the uplink transmission timing for at least one of the one or more candidate serving cells to the wireless device; Receive uplink data from the wireless device via the serving cell; and Receive uplink data from the wireless device via a specific candidate cell among the one or more candidate serving cells without a random access procedure.

Images