KR20230121043A - Method and apparatus for cell reselection in wireless communication system - Google Patents

Abstract

This disclosure relates to cell reselection in a wireless communication system. According to an embodiment of the present disclosure, a method performed by a wireless device in a wireless communication system includes receiving information related to a service time of a neighboring cell; obtaining cell quality of the neighboring cell based on measurements of the neighboring cell; determining a time from a current point in time to an end point of the service time of the neighbor cell as the remaining service time of the neighbor cell; and performing cell reselection for the neighboring cell based on the cell quality of the neighboring cell and the remaining service time for the neighboring cell.

Description

Method and apparatus for cell reselection in wireless communication system

This disclosure relates to cell reselection in a wireless communication system.

3rd Generation Partnership Project (3GPP) Long-Term Evolution (LTE) is a technology for enabling high-speed packet communication. Many schemes have been proposed for LTE goals, cost reduction for users and operators, improvement in service quality, coverage expansion, and system capacity increase. 3GPP LTE requires cost reduction per bit, improvement in service usability, flexible use of frequency bands, simple structure, open interface, and appropriate power consumption of terminals as high-level requirements.

Work has begun on the International Telecommunication Union (ITU) and 3GPP to develop requirements and specifications for New Radio (NR) systems. 3GPP identifies the technical components needed to successfully standardize NRs that meet both urgent market needs and the longer-term requirements of the ITU Radio Communication Sector (ITU-R) International Mobile Telecommunications (IMT)-2020 process in a timely manner. and must be developed. In addition, NR should be able to use any spectrum band up to at least 100 GHz that can be used for wireless communication even in the distant future.

NR targets a single technology framework that covers all deployment scenarios, usage scenarios and requirements, including enhanced mobile broadband (eMBB), massive machine type-communications (mMTC), ultra-reliable and low latency communications (URLC), and more. do. NR must be inherently forward compatible.

The UE may perform cell reselection based on its movement. For example, cell quality may be considered for cell reselection so that the UE performs cell reselection to a neighboring cell having better cell quality than the serving cell. Cell reselection can also be performed in a Non-Terrestrial Network (NTN) scenario.

An object of the present disclosure is to provide a method and apparatus for cell reselection in a wireless communication system.

Another object of the present disclosure is to provide a method and apparatus for cell reselection in a non-terrestrial network (NTN) in a wireless communication system.

According to an embodiment of the present disclosure, a method performed by a wireless device in a wireless communication system includes receiving information related to a service time of a neighboring cell; obtaining cell quality of the neighboring cell based on measurements of the neighboring cell; determining a time from a current point in time to an end point of the service time of the neighbor cell as the remaining service time of the neighbor cell; and performing cell reselection for the neighboring cell based on the cell quality of the neighboring cell and the remaining service time for the neighboring cell.

According to an embodiment of the present disclosure, a wireless device in a wireless communication system includes a transceiver; Memory; and at least one processor functionally coupled to the transceiver and the memory, wherein the at least one processor: controls the transceiver to receive information related to a service time of a neighboring cell, and to measure a neighboring cell. Acquire the cell quality of the neighboring cell based on, determine the time from the present time to the end of the service time of the neighboring cell as the remaining service time of the neighboring cell, and determine the cell quality of the neighboring cell and the neighboring cell and perform cell reselection for the neighboring cell based on the remaining service time for .

According to an embodiment of the present disclosure, in a processor for a wireless device in a wireless communication system, a memory of the wireless device stores software code embodying instructions to perform operations when executed by the processor, the operations to: Receiving information related to a service time of a neighboring cell; obtaining cell quality of the neighboring cell based on the measurement of the neighboring cell; determining a time from a current point in time to an end point in the service time of the neighbor cell as the remaining service time of the neighbor cell; and performing cell reselection with respect to the neighboring cell based on the cell quality of the neighboring cell and the remaining service time for the neighboring cell.

According to an embodiment of the present disclosure, in a non-transitory computer-readable medium (CRM) storing a plurality of instructions, when the plurality of instructions are executed by a processor of the wireless device, the wireless device: Receive information related to the service time of the neighboring cell, obtain cell quality of the neighboring cell based on the measurement of the neighboring cell, and calculate the time from the present time to the end of the service time of the neighboring cell. , and cell reselection for the neighboring cell is performed based on the cell quality of the neighboring cell and the remaining service time for the neighboring cell.

According to an embodiment of the present disclosure, a method performed by an entity related to a serving cell in a wireless communication system includes performing a random access procedure with a wireless device; establishing a connection with the wireless device; and transmitting information related to the service time of the neighboring cell to the wireless device, wherein the wireless device moves from the serving cell to the neighboring cell based on the cell quality of the neighboring cell and the remaining service time for the neighboring cell. Cell reselection is performed, and the remaining service time of the neighbor cell is determined as a time from the current point in time to the end point of the service time of the neighbor cell.

According to an embodiment of the present disclosure, an entity related to a serving cell in a wireless communication system includes a transceiver; Memory; and at least one processor functionally coupled to the transceiver and the memory, wherein the at least one processor: performs a random access procedure with a wireless device, establishes a connection with the wireless device, and controls the transceiver. and transmits information related to the service time of the neighboring cell to the wireless device, wherein the wireless device moves the cell from the serving cell to the neighboring cell based on the cell quality of the neighboring cell and the remaining service time for the neighboring cell. Reselection is performed, and the remaining service time of the neighbor cell is determined as a time from the current point in time to the end point of the service time of the neighbor cell.

The present disclosure may have various beneficial effects.

For example, the UE does not always perform cell reselection to a cell with the best cell quality. Only a cell with a remaining service time longer than the threshold may be a candidate cell for cell reselection. Alternatively, among cells whose cell quality is higher than the threshold value, the UE performs cell reselection to a cell having the longest remaining service time. Accordingly, the UE may perform cell reselection on a cell having a long remaining service time in order to prevent frequent cell reselection.

Advantageous effects obtainable through specific embodiments of the present disclosure are not limited to the above-described advantageous effects. For example, there may be various technical effects that a person skilled in the art can understand and/or derive from the present disclosure. Therefore, specific effects of the present disclosure are not limited to those explicitly described herein, and may include various effects that can be understood or derived from the technical spirit of the present disclosure.

1 shows examples of 5G usage scenarios to which the technical features of the present disclosure can be applied.
2 shows an example of a wireless communication system to which the technical features of the present disclosure can be applied.
3 shows an example of a wireless communication system to which the technical features of the present disclosure can be applied.
4 shows another example of a wireless communication system to which the technical features of the present disclosure can be applied.
5 shows a block diagram of a user plane protocol stack to which the technical features of the present disclosure may be applied.
6 shows a block diagram of a control plane protocol stack to which the technical features of the present disclosure may be applied.
7 illustrates a frame structure in a 3GPP-based wireless communication system.
8 illustrates an example of data flow in a 3GPP NR system.
9 shows an example of an NTN system to which the technical idea of the present disclosure can be applied.
10 shows an example of a method performed by a wireless device according to an embodiment of the present disclosure. The steps illustrated in FIG. 10 may also be performed by a UE.
11 shows an example of a signal flow between a wireless device and a serving/neighbor cell according to an embodiment of the present disclosure.
12 shows an example of a cell reselection method according to remaining service time according to an embodiment of the present disclosure.
13 shows a UE implementing an embodiment of the present disclosure.
14 shows an example of a wireless communication system to which the technical features of the present disclosure can be applied.
15 shows an example of an AI device to which the technical features of the present disclosure may be applied.
16 shows an example of an AI system to which the technical features of the present disclosure can be applied.

The technical features described below may be used by a communication standard by the 3rd Generation Partnership Project (3GPP) standardization organization, a communication standard by the Institute of Electrical and Electronics Engineers (IEEE), and the like. For example, communication standards by the 3GPP standardization organization include Long Term Evolution (LTE) and/or the evolution system of LTE. LTE's evolution system includes LTE-Advanced (LTE-A), LTE-A Pro, and/or 5G New Radio (NR). Communication standards by the IEEE standardization organization include wireless local area network (WLAN) systems such as IEEE 802.11a/b/g/n/ac/ax. The above system uses various multiple access techniques such as orthogonal frequency division multiple access (OFDMA) and/or single carrier frequency division multiple access (SC-FDMA) for downlink (DL) and/or uplink (UL). . For example, only OFDMA can be used for DL and only SC-FDMAA can be used for UL. Alternatively, OFDMA and SC-FDMA may be used for DL and/or UL.

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

In this disclosure, a slash (/) or comma (,) can mean “and/or”. For example, "A/B" can mean "A and/or B". Accordingly, "A/B" may mean "only A", "only B", or "both A and B". For example, "A, B, C" may mean "A, B or C".

In this disclosure, "at least one of A and B" may mean "only A", "only B" or "both A and B". Additionally, in this disclosure, the expression "at least one of A or B" or "at least one of A and/or B" may be interpreted as equivalent to "at least one of A and B".

Additionally, in this disclosure, "at least one of A, B, and C" can 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”.

Also, parentheses used in this disclosure may mean “for example”. Specifically, when parentheses are given like "Control Information (PDCCH)", "PDCCH" may be suggested as an example of "Control Information". In other words, in the present disclosure, "control information" is not limited to "PDCCH", and "PDCCH" may be suggested as an example of "control information". Also, even when given as “control information (ie, PDCCH)”, “PDCCH” may be suggested as an example of “control information”.

Technical features separately described in the drawings of the present disclosure may be implemented separately or simultaneously.

Throughout the disclosure of this disclosure, the terms 'radio access network (RAN) node', 'base station', 'eNB', 'gNB' and 'cell' may be used interchangeably. Also, a UE may be a type of wireless device, and throughout the disclosure of this disclosure, the terms 'UE' and 'wireless device' may be used interchangeably.

Throughout this disclosure, the terms 'cell quality', 'signal strength', signal quality', 'channel state', 'channel quality', 'channel state/reference signal received power (RSRP)' and 'reference Reference signal received quality (RSRQ)' may be used interchangeably.

The following figures were created to illustrate certain embodiments of the present disclosure. The names of these specific devices or the names of specific signals/messages/fields in the drawings are provided by way of example, and thus the technical features of the present disclosure are not limited to the specific names in the drawings below.

1 shows examples of 5G usage scenarios to which the technical features of the present disclosure can be applied.

The 5G usage scenario shown in FIG. 1 is for illustrative purposes only, and the technical features of the present disclosure may also be applied to other 5G usage scenarios not shown in FIG. 1 .

Referring to Figure 1, the three major requirements areas for 5G are (1) enhanced mobile broadband (eMBB) domain, (2) massive machine type communication (mMTC) domain, and (3) It covers the very high reliability and low latency communication (URLLC) domain. Some use cases may require multiple domains for optimization, while other use cases may focus on only one key performance indicator (KPI). 5G will support these diverse use cases in a flexible and reliable way.

eMBB focuses on overall improvements in data rate, latency, user density, capacity and coverage of mobile broadband access. eMBB targets transfer rates of ~10 Gbps. eMBB goes far beyond basic mobile internet access and covers rich responsive work and media access and entertainment in the cloud and/or augmented reality. Data is one of the main drivers of 5G and we may not be seeing dedicated voice services for the first time in the 5G era. In 5G, voice is expected to be handled by applications only using the data connection provided by the communication system. The main reason for the increase in traffic is the increase in the size of content and the increase in the number of applications requiring high data transmission rates. As more devices connect to the internet, such as streaming services (audio and video), responsive video and mobile internet connectivity will become more common. Many of these applications require always-on connectivity to deliver real-time information and notifications to users. Cloud storage and applications are rapidly growing on mobile communication platforms, which can be applied to both work and entertainment. Cloud storage is a particular driver driving the growth of uplink data rates. 5G is also used for remote work in the cloud and requires very low end-to-end latency to maintain a good user experience when contact interfaces are used. In entertainment, cloud gaming and video streaming, for example, are another key factor driving the demand for mobile broadband capacity. Entertainment is essential on smartphones and tablets everywhere, including in highly mobile environments such as trains, cars and airplanes. Another use case is augmented reality for entertainment and information retrieval. Here, augmented reality requires very low latency and instantaneous amount of data.

mMTC is designed to enable communication between low-cost, large-capacity battery-powered devices, supporting applications such as smart metering, logistics, and field and body sensors. mMTC targets 10 years and/or 1 million devices/km2 on batteries. mMTC enables seamless integration of embedded sensors in all areas and is one of the most widely used 5G applications. By 2020, Internet of Things (IoT) devices are expected to reach 20.4 billion. Industrial IoT is one area where 5G will play a key role in enabling smart cities, asset tracking, smart facilities, agriculture and security infrastructure.

URLLC will enable devices and devices to communicate with very high reliability, very low latency and high availability, making it ideal for vehicular communication, industrial control, factory automation, remote surgery, smart grid and public safety applications. URLLC targets ~1ms latency. URLLC includes new industry-changing services with ultra-high reliability/low latency, such as remote control of critical infrastructure and autonomous vehicles. This level of reliability and latency is essential for smart grid control, industrial automation, robotics, and drone control and coordination.

Next, a number of usage examples included in the triangle of FIG. 1 will be described in more detail.

5G will complement fiber-to-the-home (FTTH) and cable-based broadband (or DOCSIS) as a means to deliver streams with transmission rates ranging from hundreds of megabits per second to many gigabits per second. These high speeds may be required to deliver virtual reality (VR) and augmented reality (AR) as well as TVs with resolutions of 4K or higher (6K, 8K and higher). VR and AR applications include the most immersive sporting events. Certain applications may require special network settings. For example, in the case of a VR game, a game company will need to integrate its core server with the network operator's edge network server to minimize latency.

The automotive sector is expected to be an important new driver for 5G and has many use cases for applying mobile communication to vehicles. For example, entertainment for passengers requires both high capacity and high mobile bandwidth. This is because future users will expect a high-quality connection regardless of their location and speed. Another use case in the automotive sector is augmented reality dashboards. In the dark, the driver can use the augmented reality dashboard to identify objects viewed through the front window and above it. These augmented reality dashboards display information that informs the driver about the distance and motion of objects. In the future, these wireless modules will enable communication between vehicles, exchange of information between vehicles and the infrastructure supporting them, and exchange of information between vehicles and other connected devices (eg devices carried by pedestrians). A safety system enables the driver to guide a course of different actions to drive more safely, thereby reducing the risk of an accident. The next step will be remotely controlled or self-driving vehicles. This requires very reliable and very fast communication between different autonomous vehicles and between vehicles and infrastructure. In the future, autonomous vehicles will perform all driving activities, and drivers will focus only on traffic situations that cannot be identified by the vehicle itself. The technical requirements of autonomous vehicles require extremely low latency and high-speed reliability to increase traffic safety to levels that are unattainable by humans.

Smart cities and smart homes, called smart societies, will be embedded within high-density wireless sensor networks. A decentralized network of intelligent sensors will identify conditions for keeping a city or home cost and energy efficient. A similar setup can be done for each household. Temperature sensors, window and heating controllers, burglar alarms and appliances are all connected wirelessly. Many of these sensors generally require low data rates, low power and low cost. However, real-time high-definition (HD) images may be required for monitoring, for example, for certain types of devices.

The consumption and distribution of energy, including heat and gas, is highly decentralized and requires automated control of distributed sensor networks. A smart grid interconnects these sensors using digital information and communication technologies to gather information and act on it. This information may include the behavior of suppliers and consumers, enabling these smart grids to increase the distribution of fuels such as electricity in terms of efficiency, reliability, economy, production sensitivity, and automated methods. This smart grid can be viewed as another sensor network with low latency.

The health sector has many applications that could benefit from mobile communications. A communication system may support telemedicine to provide medical care at a remote location. This can help reduce barriers due to distance and improve access to health services that are not continuously available in remote rural areas. It is also used to save lives in urgent care and emergencies. Mobile communications based on wireless sensor networks can provide sensors for remote monitoring and parameters such as heart rate and blood pressure.

Wireless and mobile communications are becoming increasingly important in industrial applications. Wiring costs for installation and maintenance are high. Thus, the prospect of replacing cables with reconfigurable wireless links is attractive for many industries. However, to achieve this, it is necessary for wireless connections to operate with comparable latency, reliability, and capacity to cables, and for their management to be simplified. Low latency and very low error probability are the new requirements to be connected to 5G.

Logistics and freight tracking is an important use case for mobile communications, enabling tracking of inventory and packages at all times using location-based information systems. Logistics and freight tracking use cases typically require low data rates, but reliable location information with a wide range.

NR supports multiple numerologies (or subcarrier spacing (SCS)) to support various 5G services. For example, when the SCS is 15 kHz, a wide area in traditional cellular bands may be supported. When the SCS is 30 kHz/60 kHz, dense urban areas, low latency and wider carrier bandwidth can be supported. When the SCS is 60 kHz or higher, a bandwidth exceeding 24.25 GHz can be supported to overcome phase noise.

NR frequency bands can be defined as two types of frequency ranges, namely FR1 and FR2. The numerical values of these frequency ranges are subject to change. For example, the frequency ranges of the two types (FR1 and FR2) may be as shown in Table 1 below. For ease of explanation, in the frequency range used in NR systems, FR1 can mean "below the 6 GHz range" and FR2 can mean "above the 6 GHz range" and can be referred to as millimeter wave (mmW). there is.

Frequency ranging Corresponding frequency range subcarrier spacing FR1 450MHz - 6000MHz 15, 30, 60 kHz FR2 24250MHz - 52600MHz 60, 120, 240 kHz

As described above, the numerical value of the frequency range of the NR system can be changed. For example, FR1 may include a frequency band of 410 MHz to 7125 MHz as shown in Table 2 below. That is, FR1 may include a frequency band of 6 GHz (or 5850, 5900, 5925 MHz, etc.) or higher. For example, a frequency band of 6 GHz (or 5850, 5900, 5925 MHz, etc.) or higher included in FR1 may include an unlicensed band. Unlicensed bands may be used for various purposes, for example, for communication in vehicles (eg driverless driving).

Frequency ranging Corresponding frequency range subcarrier spacing FR1 410MHz - 7125MHz 15, 30, 60 kHz FR2 24250MHz - 52600MHz 60, 120, 240 kHz

2 shows an example of a wireless communication system to which the technical features of the present disclosure can be applied. Referring to FIG. 2 , the wireless communication system may include a first device 210 and a second device 220. The first device 210 may include a base station, a network node, a transmitting UE, a receiving UE, and a radio Devices, wireless communication devices, vehicles, vehicles equipped with driverless driving capabilities, connected cars, drones, unmanned vehicles (UAVs), artificial intelligence (AI) modules, robots, AR devices, VR devices, mixed reality (MR) devices, Including hologram devices, public safety devices, MTC devices, IoT devices, medical devices, fintech devices (or financial devices), security devices, climate/environment devices, devices related to 5G services, or devices related to the 4th industrial revolution do.

The second device 220 includes a base station, a network node, a transmitting UE, a receiving UE, a wireless device, a wireless communication device, a vehicle, a vehicle equipped with an unmanned driving function, a connected car, a drone, a UAV, an AI module, a robot, and an AR device. , VR devices, MR devices, hologram devices, public safety devices, MTC devices, IoT devices, medical devices, fintech devices (or financial devices), security devices, climate/environment devices, devices related to 5G services, or quaternary Includes devices related to the industrial revolution.

For example, UEs include mobile phones, smartphones, laptop computers, digital broadcasting terminals, personal digital assistants (PDAs), portable multimedia players (PMPs), navigation devices, slate personal computers (PCs), tablet PCs, ultrabooks, It may include a wearable device (eg, smart watch, smart glasses, head mounted display (HMD)). For example, such an HMD may be a display device worn on the head. For example, such HMDs may be used to implement AR, VR and/or MR.

For example, the drone may be a flying object that flies by a radio control signal without a human being on board. For example, the VR device may be a device that implements an object or background in a virtual world. For example, the AR device may include a device that implements a connection of objects and/or backgrounds in the virtual world to objects and/or backgrounds in the real world. For example, the MR device may include a device implementing a function of merging a virtual world object and/or background with a real world object and/or background. For example, the hologram device may include a device that implements a 360-degree stereoscopic image by recording and reproducing stereoscopic information using an interference phenomenon generated by two laser lights meeting each other, called holography. For example, a public safety device may include a video relay device or a video device worn by a user. For example, the MTC device and the IoT device may be devices that do not require direct human intervention or manipulation. For example, the MTC device and the IoT device may include a smart meter, a vending machine, a thermometer, a smart light bulb, a door lock, and/or various sensors. For example, the medical device may be a device used for diagnosis, treatment, mitigation, treatment, or prevention of a disease. For example, the medical device may be a device used for the purpose of diagnosing, treating, alleviating, or correcting an injury or disease. For example, the medical device may be a device used for the purpose of inspecting, replacing, or modifying a structure or function. For example, the medical device may be a device used for the purpose of controlling pregnancy. For example, the medical devices include treatment devices, surgical devices, (in vitro) diagnostic devices, hearing aids and/or devices for procedures, and the like. For example, a security device may be a device installed to prevent possible danger and maintain safety. For example, the security device may include a camera, a closed circuit television (CCTV), a recorder, or a black box. For example, the fintech device may be a device capable of providing financial services such as mobile payment. For example, the fintech device may include a payment device or point of sales (POS). For example, the climate/environment device may include a device for monitoring and predicting the climate/environment.

The first device 210 may include at least one or more processors such as processor 211 , at least one memory such as memory 212 , and at least one transceiver such as transceiver 213 . The processor 211 may perform functions, procedures, and/or methods of the first device described throughout the disclosure of the present disclosure. The processor 211 may perform one or more protocols. For example, the processor 211 may perform one or more layers of an air interface protocol. The memory 212 is connected to the processor 211 and may store various types of information and/or instructions. The transceiver 213 is connected to the processor 211 and can be controlled by the processor 211 to transmit and receive radio signals.

The second device 220 may include at least one or more processors such as processor 221 , at least one memory such as memory 222 , and at least one transceiver such as transceiver 223 . The processor 221 may perform functions, procedures, and/or methods of the second device 220 described throughout the present disclosure. The processor 221 may perform one or more protocols. For example, the processor 221 may perform one or more layers of an air interface protocol. The memory 222 is connected to the processor 221 and may store various types of information and/or instructions. The transceiver 223 is connected to the processor 221 and can be controlled by the processor 221 to transmit and receive radio signals.

The memories 212 and 222 may be internally or externally connected to the processors 211 and 212 or connected to other processors through various technologies such as wired or wireless connections.

The first device 210 and/or the second device 220 may have more than one antenna. For example, antenna 214 and/or antenna 224 may be configured to transmit and receive wireless signals.

3 shows an example of a wireless communication system to which the technical features of the present disclosure can be applied.

Specifically, FIG. 3 shows a system architecture based on an evolved-UMTS terrestrial radio access network (E-UTRAN). The LTE mentioned above is part of evolved-UTMS (e-UMTS) using NE-UTRA.

Referring to Figure 3, this wireless communication system includes one or more user equipment (UE) 310, an E-UTRAN and an evolved packet core (EPC). The UE 310 refers to communication equipment carried by a user. The UE 310 may be a fixed device or a portable device. The UE 310 may also be referred to by other terms such as a base station (MS), user terminal (UT), subscriber station (SS), wireless device, and the like.

An E-UTRAN consists of one or more Evolved NodeBs (eNBs) 320 . The eNB 320 provides E-UTRA user plane and control plane protocol termination to UE 10 . The eNB 320 is generally a fixed station that communicates with the UE 310 . The eNB 320 has functions such as inter-cell radio resource management (RRM), radio bearer (RB) control, connection mobility control, radio admission control, measurement configuration/provision, dynamic resource allocation (scheduler), and the like. The eNB 320 may be referred to by other terms such as a base station (BS), a basic transceiver system (BTS), an access point (AP), and the like.

Downlink (DL) refers to communication from eNB 320 to UE 310 . Uplink (UL) represents communication from UE 310 to eNB 320 . Sidelink (SL) represents communication between UEs 310 . In DL, a transmitter may be part of the eNB 320 and a receiver may be part of the UE 310 . In UL, a transmitter may be part of the UE 310 and a receiver may be part of the eNB 320 . In SL, the transmitter and receiver may be part of the UE 310 .

The EPC includes a Mobility Management Entity (MME), a Serving Gateway (S-GW) and a Packet Data Network (PDN) Gateway (P-GW). The MME has functions such as non-access stratum (NAS) security, idle state mobility handling, evolved packet system (EPS) bearer control, and the like. The S-GW has functions such as mobility anchoring, and the like. The S-GW is a gateway having E-UTRAN as an endpoint. For convenience, the MME/S-GW 330 will be simply referred to as “gateway” in this disclosure, but it should be understood that this entity includes both the MME and the S-GW. The P-GW has functions such as UE Internet Protocol (IP) address assignment, packet filtering, and the like. The P-GW is a gateway having a PDN as an endpoint. The P-GW is connected to an external network.

The UE 310 is connected to the eNB 320 through a Uu interface. The UEs 310 are connected to each other through PC5 interfaces. The eNBs 320 are connected to each other through X2 interfaces. The eNB 320 is also interconnected to the EPC via the S1 interface, more specifically to the MME via the S1-MME interface, and to via the S1-U interface, respectively. The S1 interface supports a many-to-many relationship between the MME/S-GW and eNB.

4 shows another example of a wireless communication system to which the technical features of the present disclosure can be applied.

Specifically, FIG. 4 shows a system architecture based on 5G NR. An entity used in the 5G NR (hereinafter, simply referred to as “NR”) may absorb some or all of the functions of entities introduced in FIG. 3 (e.g., eNB, MME, S-GW). The entity used in the NR may be identified with the name "NG" to distinguish it from LTE/LTE-A.

Referring to FIG. 4 , the wireless communication system includes one or more UEs 410, a next generation RAN (NG-RAN), and a 5G core network (5GC). The NG-RAN is composed of at least one NG-RAN node. The NG-RAN node is an entity corresponding to the eNB 320 shown in FIG. 3 . The NG-RAN node is composed of at least one gNB 421 and/or at least one ng-eNB 422. The gNB 421 provides NR user plane and control plane protocol termination to the UE 410 . The ng-eNB 422 provides E-UTRA user plane and control plane protocol termination to the UE 410 .

The 5GC includes an access and mobility management function (AMF), a user plane function (UPF) and a session management function (SMF). The AMF has functions such as NAS security, idle state e mobility handling, and the like. The AMF is an entity that includes the functions of a typical MME. The UPF has functions such as mobility anchoring and protocol data unit (PDU) handling. The UPF is an entity that includes functions of a typical S-GW. The SMF has functions such as UE IP address allocation and PDU session control.

The gNB 421 and the ng-eNB 422 are connected to each other through an Xn interface. The gNB 421 and the ng-eNB 422 are also interconnected to 5GC through an NG interface, more specifically to AMF through an NG-C interface, and to UPF through an NG-U interface, respectively.

The protocol structure between the network entities described above will be described. In the system of Figures 3 and/or 4, the layers of the air interface protocol between the UE and the network (e.g. NG-RAN and/or E-UTRAN) are part of the well-known Open Systems Interconnection (OSI) model in communication systems. Based on the lower three layers, it can be classified into a first layer (L1), a second layer (L2), and a third layer (L3).

5 shows a block diagram of a user plane protocol stack to which the technical features of the present disclosure may be applied. 6 shows a block diagram of a control plane protocol stack to which the technical features of the present disclosure may be applied.

The user/control plane protocol shown in Figures 5 and 6 is used in NR. However, the user/control plane protocol stack shown in FIGS. 5 and 6 can be used in LTE/LTE-A without loss of generality by replacing gNB/AMF with eNB/MME.

Referring to FIGS. 5 and 6 , a physical (PHY) layer belongs to L1. The PHY layer provides information transfer services to a medium access control (MAC) sublayer and higher layers. The PHY layer provides the MAC sublayer transport channel. Between the MAC sublayer and the PHY layer, data is transmitted through transport channels. Between different PHY layers, that is, between the PHY layer on the transmitting side and the PHY layer on the receiving side, data is transferred through physical channels.

The MAC sublayer belongs to L2. The main services and functions of the MAC sublayer include mapping between logical channels and transport channels, MAC service data units (SDUs) belonging to one or another logical channel carried from the transport block (TB) to the physical layer of the transport channel and vice versa. multiplexing/unmultiplexing of multiplexing/unmultiplexing, scheduling information reporting, error correction through hybrid automatic repeat request (HARQ), priority processing between UEs by dynamic scheduling, and communication between logical channels of one UE by logical channel priority (LCP). priority processing, etc. The MAC sublayer provides radio link control (RLC) sublayer logical channels.

The RLC sublayer belongs to L2. The RLC sublayer has three transmission modes, that is, transparent mode (TM), unacknowledged mode (UM), and acknowledged mode to guarantee various quality of service (QoS) required by radio bearers. mode: AM). The main services and functions of the RLC sublayer depend on the transmission mode. For example, the RLC sublayer provides transmission of higher layer PDUs for all three modes, but provides error correction via ARQ only via AM. In LTE/LTE-A, the RLC sublayer provides coalescence, separation and reassembly of RLC SDUs (only for UM and AM data transfers) and re-separation of RLC data PDUs (only for AM data transfers). In NR, the RLC sublayer provides separation (AM and UM only) and re-separation (AM only) of RLC SDUs and reassembly of SDUs (AM and UM only). That is, NR does not support merging of RLC SDUs. The RLC sublayer provides a Packet Data Convergence Protocol (PDCP) sublayer RLC channel.

The PDCP sublayer belongs to L2. The main services and functions of the PDCP sublayer for the user plane include header compression and decompression, forwarding of user data, duplication detection, PDCP PDU routing, PDCP SDU retransmission, encryption and decryption, and the like. The main services and functions of the PDCP sublayer for the control plane include encryption and integrity protection, transmission of control plane data, and the like.

The service data adaptation protocol (SDAP) sublayer belongs to L2. The SDAP sublayer is defined only in the user plane. The SDAP sublayer is defined only for NR. The main services and functions of SDAP include mapping between QoS flows and data radio bearers (DRBs), and marking of QoS flow IDs (QFIs) in both DL and UL packets. The SDAP sublayer provides a 5GC QoS flow.

The radio resource control (RRC) layer belongs to L3. The RRC layer is defined only on the control plane. The RRC layer controls radio resources between the UE and the network. For this purpose, the RRC layer exchanges RRC messages between the UE and the BS. The main services and functions of the RRC layer include broadcasting of system information related to AS and NAS, paging, establishment, maintenance, and release of RRC connection between the UE and the network, security functions including key management, and radio bearer establishment, configuration, and maintenance. and release, mobility function, QoS management function, UE measurement reporting and control of reporting, NAS message delivery from NAS to UE or from UE to NAS.

In other words, the RRC layer controls logical channels, transport channels, and physical channels related to radio bearer configuration, reconfiguration, and release. A radio bearer refers to a logical path provided by L1 (PHY layer) and L2 (MAC/RLC/PDCP/SDAP sublayer) for data transmission between the UE and the network. Establishing a radio bearer means defining characteristics of a radio protocol layer and a channel for providing a specific service, and setting respective parameters and operation methods. A radio bearer can be divided into a signaling RB (SRB) and a data RB (DRB). The SRB is used as a path for transmitting RRC messages in the control plane, and the DRB is used as a path for transmitting user data in the user plane.

The RRC state indicates whether the RRC layer of the UE is logically connected to the RRC layer of the E-UTRAN. In LTE/LTE-A, if the RRC connection is established between the RRC layer of the UE and the RRC layer of the E-UTRAN, the UE is in an RRC connected state (RRC_CONNECTED). Otherwise, the UE is in RRC idle state (RRC_IDLE). In NR, an RRC inactive state (RRC_INACTIVE) is additionally introduced. RRC_INACTIVE can be used for various purposes. For example, Mass Machine Type Communication (MMTC) UEs can be efficiently managed in RRC_INACTIVE. When certain conditions are met, a transition is performed from the above three states to another state.

Certain actions may be performed according to the RRC status. In RRC_IDLE, public area mobile network (PLMN) selection, broadcast of system information (SI), cell reselection mobility, core network (CN) paging and discontinuous reception (DRX) configured by NAS may be performed. The UE must be assigned an identifier (ID) that uniquely identifies the corresponding UE in the tracking area. No RRC context is stored in the BS.

In RRC_CONNECTED, the UE has an RRC connection with the network (ie E-UTRAN/NG-RAN). Network-CN connections (both C/U-plane) are also established for the UE. UE AS context is stored in the network and UE. The RAN knows which cell the UE belongs to. The network may transmit/receive data from/to the UE. Network controlled mobility including measurements are also performed.

Most operations performed in RRC_IDLE can be performed in RRC_INACTIVE. However, instead of CN paging in RRC_IDLE, RAN paging is performed in RRC_INACTIVE. In other words, in RRC_IDLE, paging for mobile terminated (MT) data is initiated by the Core Network and the paging area is managed by the Core Network. In RRC_INACTIVE, paging is initiated by the NG-RAN and the RAN-based notification area (RNA) is managed by the NG-RAN. Also, instead of DRX for CN paging configured by NAS in RRC_IDLE, DRX for RAN paging is configured by NG-RAN in RRC_INACTIVE. Meanwhile, in RRC_INACTIVE, a 5GC-NG-RAN connection (both C/U-plane) is established for the UE, and the UE AS context is stored in the NG-RAN and the UE. NG-RAN knows the RNA to which the UE belongs.

The NAS layer is located on top of the RRC layer. The NAS control protocol performs functions such as authentication, mobility management, and security control.

A physical channel can be modulated according to OFDM processing and uses time and frequency as radio resources. A physical channel consists of a number of Orthogonal Frequency Division Multiplexing (OFDM) symbols in the time domain and a number of subcarriers in the frequency domain. One subframe is composed of a plurality of OFDM symbols in the time domain. A resource block is a resource allocation unit and consists of multiple OFDM symbols and multiple subcarriers. In addition, each subframe may use a specific subcarrier of a specific OFDM symbol (eg, a first OFDM symbol) of a corresponding subframe for a physical downlink control channel (PDCCH), that is, an L1/L2 control channel. The transmission time interval (TTI) is the basic unit used by the scheduler for resource allocation. A TTI may be defined in units of one or more slots or in units of minislots.

Transmission channels are classified according to how and with what characteristics data is transmitted across the air interface. The DL transport channel includes a broadcast channel (BCH) used for transmitting system information, a downlink shared channel (DL-SCH) used for transmitting user traffic or control signals, and a channel used for paging the UE ( PCH). UL transport channels include the Uplink Shared Channel (UL-SCH) for transmitting user traffic or control signals and the Random Access Channel (RACH), which is usually used to initiate access to a cell.

Different types of data delivery services are provided by the MAC sublayer. Each logical channel type is defined by what type of information is conveyed. Logical channels are classified into two groups: control channels and traffic channels.

The control channel is used only for conveying control plane information. The control channels include a broadcast control channel (BCCH), a paging control channel (PCCH), a common control channel (CCCH), and a dedicated control channel (DCCH). The BCCH of the DL channel is broadcasting system control information. The PCCH of the DL channel carries paging information and system information exchange notification. The CCCH is a channel for transmitting control information between a UE and a network. This channel is used for UEs that do not have an RRC connection with the network. The DCCH is a point-to-point bidirectional channel for transmitting dedicated control information between a UE and a network. This channel is used for UEs with RRC connections.

The traffic channel is used only for transmission of user plane information. The traffic channel includes a dedicated traffic channel (DTCH). The DTCH is a point-to-point channel for transmitting user information and is dedicated to one UE. The DTCH may exist in both UL and DL.

Regarding mapping between logical channels and transport channels in DL, BCCH may be mapped to BCH, BCCH may be mapped to DL-SCH, PCCH may be mapped to PCH, and CCCH may be mapped to DL-SCH. DCCH may be mapped to DL-SCH, and DTCH may be mapped to DL-SCH. In UL, CCCH may be mapped to UL-SCH, DCCH may be mapped to UL-SCH, and DTCH may be mapped to UL-SCH.

7 illustrates a frame structure in a 3GPP-based wireless communication system.

The frame structure shown in FIG. 7 is purely illustrative, and the number of subframes, slots, and/or symbols in a frame may vary. In a 3GPP-based wireless communication system, OFDM numerologies (eg, subcarrier spacing (SCS), transmission time interval (TTI) duration) may be configured differently among multiple cells for one UE. For example, if the UE is configured with different SCSs for the cells aggregated for the cell, the (absolute time) period of time resource (e.g. subframe, slot, or TTI) containing the same number of symbols It may be different among these aggregated cells. In this disclosure, a symbol may include an OFDM symbol (or CP-OFDM symbol), an SC-FDMA symbol (or a Discrete Fourier Transform--Spread-OFDM (DFT-s-OFDM) symbol).

Referring to Figure 7, downlink and uplink transmissions are organized into frames. Each frame has a duration of Tf = 10 ms. Each frame is divided into two half frames, each of which has a duration of 5 ms. Each half frame consists of 5 subframes, and the period Tsf per subframe is 1 ms. Each subframe is divided into slots, and the number of slots in a subframe varies depending on the subcarrier interval. Each slot includes 14 or 12 OFDM symbols based on a cyclic prefix (CP). In normal CP, each slot contains 14 OFDM symbols, and in extended CP, each slot contains 12 OFDM symbols. The numerology is based on an exponentially scalable subcarrier spacing βf = 2u*15 kHz. The table below shows the number of OFDM symbols per slot, the number of slots per frame, and the number of slots for a normal CP according to the subcarrier spacing of βf = 2u*15 kHz.

u Nslotsymb Nframe,uslot Nsubframe,uslot 0 14 10 One One 14 20 2 2 14 40 4 3 14 80 8 4 14 160 16

The table below shows the number of OFDM symbols per slot, the number of slots per frame, and the number of slots for an extended CP for βf = 2u*15 kHz subcarrier spacing.

u Nslotsymb Nframe,uslot Nsubframe,uslot 2 12 40 4

A slot includes a number of symbols (eg, 14 or 12 symbols) in the time domain. For each numerology (eg subcarrier spacing) and carrier, a resource grid of Nsize,ugrid,x*NRBsc subcarriers and Nsubframe,usymb OFDM symbols is defined, which corresponds to higher layer signaling (eg radio A common resource block (CRB) specified by resource control (RRC) signaling) starts at Nstart,ugrid, where Nsize,ugrid,x is the number of resource blocks (RBs) in the resource grid and subscript x is DL for downlink and UL for the uplink. NRBsc is the number of subcarriers per RB. In a 3GPP-based wireless communication system, NRBsc is generally 12. There is one resource grid for a given antenna port p, subcarrier spacing configuration u, and transmission direction (DL or UL). The carrier bandwidth Nsize,ugrid for subcarrier spacing configuration u is given by a higher layer parameter (eg RRC parameter). Each element in the resource grid for antenna port p and subcarrier spacing configuration u is called a resource element (RE) and one complex symbol can be mapped to each RE. Each RE in the resource grid is uniquely identified by an index k in the frequency domain and an index l representing the position of a symbol relative to a reference point in the time domain. In a 3GPP-based wireless communication system, an RB is defined by 12 consecutive subcarriers in the frequency domain. In the 3GPP NR system, RBs are classified into CRBs and Physical Resource Blocks (PRBs). For subcarrier spacing configuration u, the CRBs are numbered from 0 upwards in the frequency domain. The center of subcarrier 0 of CRB 0 for the subcarrier spacing configuration u coincides with 'point A', which serves as a common reference point for the resource block grid. In 3GPP NR systems, PRBs are defined within bandwidth parts (BWP) and numbered from 0 to NsizeBWP,i-1, where i is the number of bandwidth parts. The relationship between the physical resource block nPRB and the common resource block nCRB in bandwidth portion i is as follows: nPRB = nCRB + NsizeBWP,i, where NsizeBWP,i is the common resource block whose bandwidth portion starts with CRB 0. The BWP includes a number of contiguous RBs. A carrier may include up to N (eg, 5) BWPs. A UE can be configured with one or more BWPs on a given component carrier. Among the BWPs, only one BWP configured with the UE can be activated at one time. The activated BWP defines the UE's operating bandwidth within the cell's operating bandwidth. In this disclosure, the term "cell" refers to a geographic area, or radio resource, in which one or more nodes provide a communication system. A "cell" of a geographical area can be understood as coverage within which a service can be provided using a carrier, and a "cell" as a radio resource (eg time-frequency resource) is a bandwidth that is a frequency range configured by the carrier. (bandwidth: BW). A “cell” associated with a radio resource is defined by a combination of downlink and uplink resources, eg, a combination of a downlink (DL) component carrier (CC) and an uplink (UL) CC. The cell may consist of only downlink resources, or may consist of downlink resources and uplink resources. Since DL coverage, the range within which a node can transmit valid signals, and UL coverage, within which a node can receive valid signals from a UE, depend on the carrier carrying the signal, the node's coverage is used by the node. It can be associated with the coverage of the "cell" of the radio resource being used. Accordingly, the term "cell" may sometimes be used to denote the service coverage of a node, in other cases a radio resource, or in other cases the range over which a signal using the radio resource can reach with effective strength.

In carrier aggregation (CA), two or more CCs are aggregated. A UE can simultaneously perform reception or transmission on one or multiple CCs according to its capacity. CA is supported for both combustion and non-continuous CC. When CA is configured, the UE has only one radio resource control (RRC) connection with the network. In RRC connection establishment / re-establishment / handover, one serving cell provides non-access stratum (NAS) mobility information, and in RRC connection establishment / re-establishment / handover, one serving cell Provide secure input. This cell is called a primary cell (PCell). A PCell is a cell operating on a primary frequency, in which a UE performs an initial connection establishment procedure or initiates a connection re-establishment procedure. Depending on the capacity of the UE, a secondary cell (SCell) may be configured to form a set of serving cells together with the PCell. SCell is a cell that provides additional radio resources on top of a special cell. Therefore, the set of serving cells configured for a UE always consists of one PCell and one or more SCells. For dual connectivity operation, the term Special Cell (SpCell) refers to a PCell of a Master Cell Group (MCG) or a PSCell of a Secondary Cell Group (SCG). SpCell supports PUCCH transmission and contention-based random access, and is always active. An MCG is a group of serving cells associated with a master node and consists of a SpCell (PCell) and optionally one or more SCells. A SCG is a subset of serving cells associated with a secondary node and consists of a PSCell and zero or more SCells for a UE configured with dual connectivity (DC). There is only one serving cell containing the PCell for UEs for which RRC_CONNECTED is not configured as CA/DC. For a UE in RRC_CONNECTED configured as CA/DC, the term "serving cell" is used to denote the set of cells containing the SpCell(s) and all SCells. In DC, two MAC objects are configured within one UE, one for MCG and one for SCG.

8 illustrates an example of data flow in a 3GPP NR system.

In FIG. 8, "RB" represents a radio bearer and "H" represents a header. Radio bearers are classified into two groups: data radio bearers (DRB) for user plane data and signaling radio bearers (SRB) for control plane data. The MAC PDU is transmitted/received to/from an external device through the PHY layer using radio resources. These MAC PDUs arrive at the PHY layer in the form of transport blocks.

In the PHY layer, the uplink transport channels UL-SCH and RACH are mapped to their physical channels PUSCH and PRACH, respectively, and the downlink transport channels DL-SCH, BCH and PCH are mapped to PDSCH, PBCH and PDSCH, respectively. In the PHY layer, uplink control information (UCI) is mapped to PUCCH, and downlink control information (DCI) is mapped to PDCCH. The MAC PDU related to the UL-SCH is transmitted by the UE on the basis of a UL grant through the PUSCH, and the MAC PDU related to the DL-SCH is transmitted by the BS through the PDSCH based on the DL designation.

In the present disclosure, the data unit(s) (eg PDCP SDU, PDCP PDU, RLC SDU, RLC PDU, RLC SDU, MAC SDU, MAC CE, MAC PDU) is a resource allocation (eg UL grant, DL designation) Based on this, it is transmitted/received on a physical channel (eg, PDSCH, PUSCH). In this disclosure, uplink resource allocation is also referred to as uplink grant, and downlink resource allocation is also referred to as downlink designation. Such resource allocation includes time domain resource allocation and frequency domain resource allocation. In this disclosure, an uplink grant is dynamically received on PDCCH by a UE in a Random Access Response, or partially coherently configured to the UE by RRC. In this disclosure, the downlink designation is dynamically received by the UE on the PDCCH or set semi-persistently to the UE by RRC signaling from the BS.

Hereinafter, a cell reselection evaluation procedure will be described.

The absolute priority of different NR frequencies or inter-RAT frequencies may be provided to the UE by inheriting from other RATs in system information, RRCRelease messages, or inter-RAT cell (re)selection. In the case of system information, NR frequencies or inter-RAT frequencies may be listed without providing a priority (ie, there is no cellReselectionPriority field for that frequency). If priority is provided in dedicated signaling, the UE shall ignore all priorities provided in system information. When the UE is in the camped on any cell state, the UE shall apply only the priority provided by the system information of the current cell, and unless otherwise specified, the UE shall apply the priority received from dedicated signaling and RRCRelease. Preserve the priority provided by deprioritisationReq. If a UE in a normally camped state has only a dedicated priority other than the current frequency, the UE should consider the current frequency as the lowest priority frequency (ie, lower than the network configuration value). When the UE is configured to perform both NR sidelink communication and V2X sidelink communication, the UE may consider a frequency providing both NR sidelink communication configuration and V2X sidelink communication configuration as the highest priority. If the UE is configured to perform NR sidelink communication and does not perform V2X communication, the UE may consider a frequency providing NR sidelink communication configuration as the highest priority. If the UE is configured to perform V2X sidelink communication and does not perform NR sidelink communication, the UE may consider a frequency providing V2X sidelink communication configuration as the highest priority.

Frequencies that only provide anchor frequency settings should not give priority to V2X services during cell reselection.

When a UE configured to perform NR sidelink communication or V2X sidelink communication performs cell reselection, frequencies providing intra-carrier and inter-carrier settings may be considered to have the same priority in cell reselection. .

Priority among frequencies that the UE considers to be the highest priority frequency is left to the UE implementation.

The UE is configured to perform V2X sidelink communication or NR sidelink communication if it has the capability and has authority for the corresponding sidelink operation.

If the UE is configured to perform both NR sidelink communication and V2X sidelink communication, but cannot find a frequency capable of providing both NR sidelink communication setup and V2X sidelink communication setup, the UE sets up NR sidelink communication or V2X A frequency providing sidelink communication configuration may be considered as the highest priority.

The UE shall perform cell reselection evaluation only for NR frequencies and inter-RAT frequencies provided in the system information and having priority provided by the UE.

If the UE receives an RRCRelease with deprioritisationReq, the UE resets the current frequency and the stored frequency or all frequencies in NR to the lowest priority frequency (i.e. lower than the network set value) due to the previously received RRCRelease with deprioritisationReq. should be considered On the other hand, T325 runs regardless of the camped RAT. The UE must delete the stored priority release request(s) when PLMN selection or SNPN selection is performed according to the request of the NAS.

The UE must seek a higher priority layer for cell reselection as soon as possible after the priority is changed.

The UE shall delete the priority provided by dedicated signaling in the following cases:

- UE enters another RRC state; or

- the optional validity time of dedicated priority (T320) expires; or

- UE receives RRCRelease message without cellReselectionPriorities field; or

- PLMN selection or SNPN selection is performed at the request of the NAS.

The UE will not consider any blacklisted cell as a candidate for cell reselection.

The UE, if configured, shall consider only whitelisted cells as candidates for cell reselection.

A UE in the RRC_IDLE state must take over the priority provided by dedicated signaling and the remaining valid time (ie, T320 of NR and E-UTRA) when inter-RAT cell (re)selection.

The network may assign dedicated cell reselection priorities to frequencies not set by system information.

If the serving cell satisfies Srxlev > SIntraSearchP and Squal > SIntraSearchQ, the UE may choose not to perform intra-frequency measurement.

The UE shall apply the following rules for NR inter-frequency and inter-RAT frequencies indicated in the system information and for which the UE has priority:

1) For an NR inter-frequency or inter-RAT frequency having a reselection priority higher than the reselection priority of the current NR frequency, the UE performs measurement of the higher priority NR inter-frequency or inter-RAT frequency Should be.

2) For NR inter-frequencies with reselection priorities equal to or lower than the reselection priority of the current NR frequency and inter-RAT frequencies with reselection priorities lower than the reselection priority of the current NR frequency:

- If the serving cell satisfies Srxlev > SnonIntraSearchP and Squal > SnonIntraSearchQ, the UE may choose not to perform measurement of NR inter-frequency or inter-RAT frequency cells having the same or lower priority.

- Otherwise, the UE shall perform measurement of NR inter-frequency or inter-RAT frequency cells of the same or lower priority.

- If the UE supports relaxed measurements and the relaxed measurements exist in SIB2, the UE can further relax the necessary measurements.

Hereinafter, cell selection criteria and cell reselection criteria will be described.

(1) Cell selection criteria

The cell selection criterion S (or criterion S) is satisfied when Srxlev > 0 and Squal > 0, where Srxlev=Qrxlevmeas-(Qrxlevmin+Qrxlevminoffset)-Pcompensation-Qoffsettemp- and Squal=Qqualmeas--(Qqualmin -+Qqualminoffset) -Qoffsettemp. Table 5 shows the definition of each parameter:

Srxlev Cell Select RX Level Value (dB) Squal Cell selection quality value (dB) Qoffset _temp Offset temporarily applied to cells Q _rxlevmeas Q _qualmeas Measurement cell RX level value (RSRP)
Measured Cell Quality Value (RSRQ) Q _rxlevmin The minimum required RX level in the cell (dBm). If the UE supports a SUL frequency for this cell, Qrxlevmin is obtained from q-RxLevMinSUL, if present, in addition to SIB1, SIB2, and SIB4, if QrxlevminoffsetcellSUL is present in SIB3 and SIB4 for that cell, this cell specific It is added to the corresponding Qrxlevmin to achieve the minimum required RX level in the relevant cell. Otherwise Qrxlevmin is obtained from q-RxLevMin of SIB1, SIB2 and SIB4. In addition, if Qrxlevminoffsetcell is present in SIB3 and SIB4 of that cell, this cell specific offset is added to that Qrxlevmin to achieve the minimum required RX level in that cell. Q _-qualmin The minimum quality level (in dB) required by the cell. In addition, when Qqualminoffsetcell is signaled for a corresponding cell, this cell-specific offset is added to achieve the minimum quality level required in the corresponding cell. Q _{rxlevminoffset} Offset for signal Q _rxlevmin considered in Srxlev evaluation as a result of periodic search for higher priority PLMN during normal camping in VPLMN. _{Qqualminoffset} Offset for signal Q _qualmin considered in Squal evaluation as a result of periodic search for a higher priority PLMN during normal camping in VPLMN. P _compensation For FR1, if UE supports additionalPmax in NR-NS-PmaxList if present in SIB1, SIB2 and SIB4: max(PEMAX1 -PPowerClass, 0) - (min(PEMAX2, PPowerClass) - min(PEMAX1, PPowerClass) ) (dB);
Otherwise:
Max(PEMAX1 -PPowerClass, 0) (dB)
For FR2, Pc _oppensation is set to 0. P _EMAX1 , P _EMAX2 The maximum TX power level of the UE can be used when transmitting in the uplink of the cell (dBm). If the UE supports SUL frequencies for this cell, P _EMAX1 and P _EMAX2 are obtained from p-Max for SUL in SIB1 and NR-NS-PmaxList for SULs in SIB1, SIB2 and SIB4, respectively, otherwise P _EMAX1 and P _EMAX2 are obtained from p-Max and NR-NS-PmaxList in SIB1, SIB2 and SIB4, respectively, for normal UL. P _-PowerClass Maximum RF output power (dBm) of the UE according to the UE power class.

The signaled values Qrxlevminoffset and Qqualminoffset are applied only when a cell is evaluated for cell selection as a result of periodically searching for a higher priority PLMN in a normally camped state in the VPLMN. During this periodic search for a higher priority PLMN, the UE can use stored parameter values from other cells in this higher priority PLMN to check the cell's S criteria. (2) NR inter-frequency and inter-RAT cell reselection criteria

If threshServingLowQ is broadcast in system information and more than 1 second has elapsed since the UE camped on the current serving cell, a cell with a higher priority NR or EUTRAN RAT/frequency satisfies Squal > ThreshX, HighQ during the time interval TreselectionRAT Cell reselection must be performed to a cell on an NR frequency or an inter-RAT frequency with a higher priority than the serving frequency.

Otherwise, cell reselection for a cell on a higher priority NR frequency or inter-RAT frequency than the serving frequency should be performed in the following cases:

- a cell of higher priority RAT/frequency satisfies Srxlev > ThreshX, HighP during the time interval TreselectionRAT; and

- More than 1 second has elapsed since the UE camped on the current serving cell.

Cell reselection for cells of the same priority NR frequency is based on ranking for cell reselection within the frequency.

If threshServingLowQ is broadcast in system information and more than 1 second has elapsed since the UE camped on the current serving cell, the serving cell satisfies Squal < ThreshServing, LowQ and is a cell with a lower priority NR or E-UTRAN RAT/frequency When Squal > ThreshX, LowQ is satisfied during the TreselectionRAT time interval, cell reselection must be performed to a cell on a priority NR frequency or inter-RAT frequency lower than the serving frequency.

Otherwise, cell reselection for a cell on a priority NR frequency or inter-RAT frequency lower than the serving frequency should be performed in the following cases:

- The serving cell satisfies Srxlev < ThreshServing, LowP and the cell of lower priority RAT/frequency satisfies Srxlev > ThreshX, LowP during the time interval TreselectionRAT. and,

- When more than 1 second has elapsed since the UE camped on the current serving cell.

Cell reselection to a higher priority RAT/frequency will take precedence over a lower priority RAT/frequency if multiple cells of different priorities meet the cell reselection criteria.

If more than one cell meets the above criteria, the UE shall reselect the cell as follows:

- If the highest priority frequency is an NR frequency, the highest ranking cell among cells on the highest priority frequency(s) that satisfies the criterion.

- If the highest priority frequency is from another RAT, the strongest cell among the cells on the highest priority frequency(s) meeting the criterion of that RAT.

(3) Inter-frequency cell reselection criteria of equal frequency and equal priority

The cell ranking criterion Rs for the serving cell is defined as Rs = Qmeas,s + Qhyst - Qoffsettemp. A cell ranking criterion Rn for a neighboring cell is defined as Rn = Qmeas,n-Qoffset-Qoffsettemp.

Table 6 shows the definition of each parameter:

Qmeas RSRP measurement level used for cell reselection Qoffset For intra-frequency: equal to Qoffsets,n if Qoffsets,n is valid, otherwise 0. For inter-frequency: equal to Qoffsets,n plus Qoffsetfrequency, if Qoffsets,n is valid. Otherwise, equal to Qoffsetfrequency. Qoffsettemp Offset temporarily applied to cells

Rs may also be referred to as a cell ranking value for a serving cell. Rn may also be referred to as a cell ranking value for a neighboring cell. The UE must rank all cells that satisfy the cell selection criterion S. Cells are ranked according to the R criterion described above by deriving Qmeas,n and Qmeas,s and calculating the R value using the average RSRP result. If rangeToBestCell is not set, the UE re-cells to the highest ranked cell. choice must be made.

When rangeToBestCell is set, the UE must perform cell reselection to a cell with the largest number of beams equal to or greater than a threshold value (ie, absThreshSS-BlocksConsolidation) among cells with the highest R value within rangeToBestCell of the highest R value. If there are several such cells, the UE must perform cell reselection with the highest ranked cell among them.

In all cases, the UE should reselect a new cell only if the following conditions are met:

- the new cell is superior to the serving cell according to the cell reselection criteria specified above during the TreselectionRAT time interval;

- When more than 1 second has elapsed since the UE camped on the current serving cell.

If rangeToBestCell is set but absThreshSS-BlocksConsolidation is not set at NR frequencies, the UE considers that there is one beam above the threshold for each cell at that frequency.

The UE may receive system information including a cell reselection parameter through broadcast signaling from a serving cell. Cell reselection parameters are defined in section 5.2.4.7.0 of 3GPP TS 38.304 V16.2.0 (2020-09).

Hereinafter, a non-terrestrial network (NTN) will be described.

9 shows an example of an NTN system to which the technical idea of the present disclosure can be applied.

NTN may refer to a network or network segment using RF resources mounted on a satellite (or an unmanned aerial system (UAS) platform). NTN may provide access to the UE.

One or more sat-gateways may connect NTN to the data network. Geostationary earth orbit (GEO) satellites may be served by one or several satellite gateways deployed over satellite coverage (eg regional or continental coverage). A UE in a cell can be served by only one sat-gateway. Non-GEO satellites can be continuously serviced by one or several sat-gateways at a time. The system can ensure service and feeder link continuity between successive serving satellite gateways with a time duration sufficient to proceed with mobility anchoring and handover.

A feeder link or radio link may be established between the sat-gateway and the satellite (or UAS platform).

A service link or radio link may be established between the user equipment and the satellite (or UAS platform).

A satellite (or UAS platform) may implement a transparent or regenerative (including onboard processing) payload. A satellite (or UAS platform) can produce multiple beams for a given service area limited by the satellite's field of view. The footprint of a beam (or beam projection area) may typically be elliptical. The field of view of a satellite (or UAS platform) may vary depending on the onboard antenna diagram and minimum elevation angle.

A cell of a satellite (eg, an NTN cell) may include one or more of all projection areas of beams generated by the satellite over a given service area defined by the satellite's field of view. A satellite may be associated with one or more cells.

Transparent payloads can be processed based on radio frequency filtering, frequency conversion and amplification. Therefore, the waveform signal repeated by the payload may not be changed.

The playback payload may be processed based on demodulation/decoding, switching and/or routing, coding/modulation as well as radio frequency filtering, frequency conversion and amplification. The processing may be substantially the same as having all or part of a base station (eg gNB) functionality onboard a satellite (or UAS platform).

An inter-satellite link (ISL) can be selectively set in case of satellite deployment. The ISL may require a regenerative payload mounted on the satellite. ISLs can operate in RF frequencies or optical bands.

A UE may be served by a satellite (or UAS platform) within a target service area.

The service time of a satellite (or NTN cell) may be a period during which the satellite can provide a service to a UE through one or more beams in the service area of the satellite (or NTN cell). A satellite's service area may be limited by the satellite's field of view. For example, the service time of an NTN cell in idle/inactive mode may be the time the UE can camp on the NTN cell. As another example, the service time of the NTN cell in the connected mode may be a period during which the UE may perform mobility (eg, handover) and/or random access procedures toward the NTN cell.

The types of satellites (or UAS platforms) are listed in Table 7:

platform altitude range orbit Typical beam projection area size Low-Earth Orbit (LEI) satellites 300 - 1500 km orbiting the earth in a circle 100 - 1000 km medium-earth orbit (MEO) satellites 7000 - 25000 km 100 - 1000 km Geostationary Earth Orbit (GEO) satellites 35,786 km Nominal station holding a fixed position in elevation/azimuth relative to a given earth point 200 - 3500 km UAS platform (including HAPS) 8 - 50 km (20 km for HAPS) 5 - 200 km High Elliptical Orbit (HEO) satellites 400 - 50000 km orbit around the earth in an elliptical shape 200 - 3500 km

GEO satellites and UAS can be used to provide continental, regional or local services. Constellations of LEO and MEO can be used to provide services in both the northern and southern hemispheres. In some cases, constellations may provide global coverage including polar regions. Constellations may require proper orbital inclination, sufficient beams generated, and inter-satellite links. On the other hand, in NTN, LEO satellites may orbit around the Earth, and each LEO satellite may have a different orbit and orbit period. Therefore, LEO satellites can be visible to terrestrial UEs only during a specific period of time, which can be referred to as service time. Therefore, even if the NTN cell is measured with good quality, the NTN cell may not be seen soon depending on the remaining service time. Therefore, if only cell quality is considered for cell selection/reselection in the NTN scenario, cell selection/reselection may become unnecessary cell selection/reselection because the remaining service time of the selected/reselected cell is not sufficient. As soon as the service time of the new serving cell expires, the UE must perform cell reselection to another cell.

Therefore, the NTN cell selection/reselection criterion should consider the service time condition so that the UE can perform cell selection/reselection to a cell capable of providing sufficient service time.

In the present disclosure, when the UE evaluates the cell reselection criterion, the service time condition may be considered in addition to the measured cell quality. For example, the UE may perform cell reselection on a cell in which the measured cell quality is higher than a set threshold and the corresponding cell has the longest service time among cell reselection candidate cells. As another example, the UE may perform cell reselection on a cell whose service time is longer than a set threshold and whose cell quality measured for the cell is the highest among candidate cells for cell reselection.

10 shows an example of a method performed by a wireless device according to an embodiment of the present disclosure. The steps illustrated in FIG. 10 may also be performed by a UE.

Referring to FIG. 10 , in step S1001, a wireless device may receive information related to a service time of a neighboring cell.

In step S1003, the wireless device may acquire the cell quality of the neighboring cell based on the measurement of the neighboring cell.

In step S1005, the wireless device may determine the time from the current point in time to the end point of the service time of the neighbor cell as the remaining service time of the neighbor cell.

In step S1007, the wireless device may perform cell reselection for a neighboring cell based on the cell quality of the neighboring cell and the remaining service time for the neighboring cell.

According to various embodiments, the service time of a neighboring cell may include: a period of time during which a wireless device is serviced by an entity in the service area of the entity associated with the neighboring cell; a period during which a wireless device may camp on a neighboring cell in idle mode or inactive mode; or a period during which the wireless device may perform a mobility or random access procedure in a connected mode.

According to various embodiments, the service area may include at least one of a coverage area of a neighboring cell or an area bounded by a field of view of the entity.

According to various embodiments, the information related to the service time of the neighbor cell may include at least one of a start time of the service time of the neighbor cell and an end time of the service time of the neighbor cell.

According to various embodiments, the information related to the service time of the neighbor cell may include a timer value corresponding to the service time of the neighbor cell.

According to various embodiments, the wireless device may start a timer having the timer value immediately after receiving information related to a service time of a neighboring cell. The wireless device may determine the remaining time of the timer by subtracting the elapsed time of the timer from the time the timer starts to the current point in time from the timer value. The remaining service time for the neighbor cell may correspond to the remaining time of the timer.

According to various embodiments, the wireless device may determine a neighboring cell for cell reselection from among neighboring cells based on a corresponding cell quality for each neighboring cell and a corresponding remaining service time for each neighboring cell.

According to various embodiments, the neighboring cells may include one or more unbarred neighboring cells whose remaining service time is greater than or equal to a barring threshold set by the network.

According to various embodiments, a wireless device may determine one or more neighboring cells having cell quality higher than a cell quality threshold set by a network among neighboring cells. The wireless device may determine a neighboring cell having the longest remaining service time among one or more neighboring cells.

According to various embodiments, a wireless device may determine one or more neighboring cells having a remaining service time longer than a remaining service time threshold set by a network among neighboring cells. The wireless device may determine a neighboring cell having the highest cell quality among one or more neighboring cells.

According to various embodiments, the cell quality of a neighboring cell may include at least one of a cell selection reception (RX) level value of a neighboring cell, a cell selection quality value of a neighboring cell, or a cell rank value of a neighboring cell.

According to various embodiments, a neighbor cell may include a Non-Terrestrial Network (NTN) cell.

According to various embodiments, a wireless device may receive measurement settings. The measurement configuration may include one or more neighboring cell lists and information about service time of each of the one or more neighboring cells. A wireless device may perform neighbor cell measurements. The wireless device may calculate the cell quality and remaining service time of each of the one or more neighboring cells. The remaining service time may be a length of time from a current time point to a service end point of one or more neighboring cells. The wireless device may perform cell reselection to a neighboring cell from among one or more neighboring cells based on both cell quality and remaining service time.

11 shows an example of a signal flow between a wireless device and a serving/neighbor cell according to an embodiment of the present disclosure.

Referring to FIG. 11 , in step S1101, an entity related to a serving cell may transmit information related to a service time of a neighboring cell to a wireless device.

In step S1103, the wireless device may obtain the cell quality of the neighboring cell based on the measurement of the neighboring cell.

In step S1105, the wireless device may determine the time from the current point in time to the end point of the service time of the neighbor cell as the remaining service time of the neighbor cell.

In step S1107, the wireless device may determine a neighboring cell for cell reselection based on the cell quality of the neighboring cell and the remaining service time of the neighboring cell. For example, the wireless device may determine a neighboring cell for cell reselection from among neighboring cells based on a corresponding cell quality for each of the neighboring cells and a corresponding remaining service time for each of the neighboring cells.

In step S1109, the wireless device may perform cell reselection for a neighboring cell based on the cell quality of the neighboring cell and the remaining service time for the neighboring cell.

In FIG. 11 , an entity related to a serving cell may be an example of the second device 220 of 2 . Accordingly, the steps of entities related to the serving cell as shown in FIG. 11 may be implemented by the second device 220 . For example, processor 221 may be configured to perform a random access procedure with a wireless device. Processor 221 may be configured to establish a connection with a wireless device. The processor 221 may be configured to control the transceiver 223 to transmit information related to a service time of a neighboring cell to a wireless device. Cell reselection from the serving cell to the neighboring cell may be performed by the wireless device based on the cell quality of the neighboring cell and the remaining service time for the neighboring cell. The remaining service time of the neighbor cell may be determined as a time from the current point in time to the end point of the service time of the neighbor cell.

12 shows an example of a cell reselection method according to remaining service time according to an embodiment of the present disclosure. The steps illustrated in FIG. 12 may be performed by a wireless device and/or UE.

Referring to FIG. 12 , in step S1201, the UE may receive measurement configuration including information about service time of each neighboring cell. The UE may be in RRC_CONNECTED state, RRC_INACTIVE state or RRC_IDLE state.

For example, measurement settings can be broadcast via system information. As another example, measurement settings may be provided through dedicated signaling.

Measurement configuration may further include a neighbor cell list. Neighboring cells may be measurement targets.

A neighbor cell may be an NTN cell. For example, NTN cells may be provided via LEO satellites. LEO satellites can provide Earth moving beams. LEO satellites can provide earth-fixed beams. As another example, NTN cells may be provided via GEO satellites.

The UE may allow cell reselection for a corresponding cell only within the service time of the corresponding cell. For example, when an LEO satellite with an earth-fixed beam tries to perform beam switching, the satellite may not provide NTN service for a while. In this case, the service time may be possible only until beam switching starts. As another example, when an LEO satellite tries to perform feeder link switching, the satellite may not be able to provide NTN service for a while. In this case, service time may be possible only after feeder link switching is completed.

Information on service time may be set as an absolute time period (eg, UTC time). For example, the information on the service time may include at least one of a start time of the service time or an end/stop time of the service time.

Information about the service time may be set as a relative time period (eg, timer). For example, the service time information may include a timer value corresponding to the service time.

The measurement setting may further include a first threshold (eg, a barring threshold). The first threshold may be a time length threshold associated with blocking a corresponding neighbor cell whose remaining service time is less than the first threshold.

The measurement setting may further include a second threshold. The second threshold may be a cell quality threshold.

The measurement setting may further include a third threshold (eg, remaining service time threshold). The third threshold may be a time length threshold associated with reselection of a corresponding neighbor cell whose remaining service time is longer than the third threshold. The third threshold may be the same as the first threshold. That is, only one of the first threshold and the third threshold may be set in the measurement setting.

In step S1203, the UE may perform neighbor cell measurement based on the measurement configuration. The UE may perform measurement based on the neighbor cell list included in the measurement configuration.

In step S1205, the UE may calculate cell quality and/or cell ranking of each neighbor cell based on the measurement of the neighbor cell. The cell quality may include at least one of an R value (eg, a cell rank value) or an S value (eg, a cell selection RX level value/cell selection quality value). The cell ranking criterion Rs for the serving cell is defined as Rs=Qmeas,s+Qhyst-Qoffsettemp. A cell ranking criterion Rn for a neighboring cell is defined as Rn=Qmeas,n-Qoffset-Qoffsettemp. Table 6 shows the definition of each parameter.

In step S1207, the wireless device may calculate the remaining service time of each neighboring cell based on the service time information of each neighboring cell.

When the service time information is set as an absolute time, the remaining service time may be a time from a current time point to a service end time point.

For example, if the service provision time of the neighboring cell is from 08:10 UTC to 08:20 UTC and the current time is 08:16 UTC, the remaining service time is 4 minutes (time between 08:16 and 08:20 UTC).

When the service time information is set as a relative time, the remaining service time may mean a remaining time from a current time point to a service end time point.

For example, the information about the service time of the neighbor cell may include a timer value corresponding to the service time of the neighbor cell. The UE may start a timer having a timer value when receiving information about the service time of a neighboring cell. The UE may determine the remaining time of the timer as a value obtained by subtracting an elapsed time from the timer start time to the current time point from the timer value. The remaining service time for the neighbor cell may correspond to the remaining time of the timer.

For example, if the service time (eg, timer value) of the neighboring cell is provided as 15 minutes and the timer elapsed time from the time the timer started to the current time is 7 minutes, the remaining time will be determined as 8 minutes of the timer. can That is, the remaining service time for neighboring cells may be 8 minutes.

In step S1209, the UE may identify one or more neighboring cells that are considered blocked based on the remaining service time. Based on the remaining service time, the UE may treat the neighboring cell as blocked if the remaining service time of the neighboring cell is shorter than the first threshold included in the measurement configuration.

In step S1211, the UE may perform cell reselection to an unblocked cell based on cell quality and remaining service time. Based on the cell quality and remaining service time, the UE may perform cell reselection evaluation to reselect a cell and perform cell reselection toward the reselected cell.

For example, among neighboring cells whose cell quality is higher than the second threshold, the UE may perform cell reselection to a cell having the longest remaining service time.

As another example, the UE may perform cell reselection to a cell having the highest cell quality among neighboring cells having a remaining service time longer than the third threshold.

13 shows a UE implementing an embodiment of the present disclosure. The invention described above for the UE side can also be applied to this embodiment. In FIG. 13 , the UE may be an example of the first device 210 shown in FIG. 2 .

The UE includes a processor 1310 (ie processor 211), a power management module 1311, a battery 1312, a display 1313, a keypad 1314, a subscriber identity module (SIM) card 1315, memory ( 1320) (ie, memory 212), a transceiver 1330 (ie, transceiver 213), one or more antennas 1331, a speaker 1340, and a microphone 1341.

The processor 1310 may be configured to implement the proposed functions, procedures and/or methods described herein. Layers of an air interface protocol may be implemented in the processor 1310 . The processor 1310 may include an application-specific integrated circuit (ASIC), other chipsets, logic circuits, and/or data processing devices. The processor 1310 may be an application processor (AP). The processor 1310 may include at least one digital signal processor (DSP), a central processing unit (CPU), a graphic processing unit (GPU), and a modem (modulation and demodulation). Examples of the processor 1310 are SNAPDRAGON ^™ series processors manufactured by Qualcomm®, EXYNOS ^™ series processors manufactured by Samsung®, and Apple® manufactured There is a series of processors, the HELIO ^TM series processor manufactured by MediaTek®, the ATOM ^TM series processor manufactured by Intel®, or the corresponding next-generation processor.

The processor 1310 may be configured to implement steps performed by the UE and/or the wireless device throughout the teachings of this disclosure or configured to control the transceiver 1330 .

The power management module 1311 manages power of the processor 1310 and/or the transceiver 1330 . The battery 1312 supplies power to the power management module 1311 . The display 1313 outputs a result processed by the processor 1310. The keypad 1314 receives input to be used by the processor 1310. The keypad 1314 may be visible on the display 1313 . The SIM card 1315 is an integrated circuit for securely storing an International Mobile Subscriber Identity (IMSI) number used to identify and authenticate a subscriber on a mobile phone communication device (such as a cell phone and a computer) and a key related thereto. It is also possible to store contact information on many SIM cards.

The memory 1320 is operably connected to the processor 1310 and stores various information for operating the processor 1310 . The memory 1320 may include read-only memory (ROM), random access memory (RAM), flash memory, memory card, storage medium, and/or other storage devices. When these embodiments are implemented as software, the techniques described in this disclosure may be implemented as modules (eg, procedures, functions, etc.) for performing the functions described in this disclosure. The module may be stored in the memory 1320 and executed by the processor 1310 . The memory 1320 may be implemented within the processor 1310 or may be external to the processor 1310, in which case they may be communicatively connected to the processor 1310 through various means well known in the art. .

The transceiver 1330 is operatively connected to the processor 1310 and transmits and/or receives a radio signal. The transceiver 1330 includes a transmitter and a receiver. The transceiver 1330 may include base band circuitry for processing radio frequency signals. The transceiver 1330 controls one or more antennas 1331 for transmitting and/or receiving radio signals.

The speaker 1340 outputs a sound-related result processed by the processor 1310. The microphone 1341 receives sound-related input to be used by the processor 1310.

According to various embodiments, the processor 1310 is configured to implement steps performed by the UE and/or wireless device in the present disclosure, or controls the transceiver 1330 to perform steps performed by the UE and/or wireless device in the present disclosure. It can be set to implement the steps to be. For example, the processor 1310 may be configured to control the transceiver 1330 to receive information related to service time of neighboring cells. Processor 1310 may be configured to obtain a cell quality of a neighboring cell based on measurements of the neighboring cell. The processor 1310 may be configured to determine the time from the current point in time to the end point of the service time of the neighbor cell as the remaining service time of the neighbor cell. Processor 1310 may be configured to perform cell reselection for a neighboring cell based on the cell quality of the neighboring cell and the service time remaining for the neighboring cell.

14 shows an example of a wireless communication system to which the technical features of the present disclosure can be applied.

Referring to FIG. 14 , the wireless communication system may include a first device 1410 (ie, the first device 210) and a second device 1420 (ie, the second device 220).

The first device 1410 may include at least one transceiver such as the transceiver 1411 and at least one processing chip such as the processing chip 1412 . The processing chip 1412 may include at least one processor, such as a processor 1413, and at least one memory, such as a memory 1414. The memory may be operably coupled to the processor 1413. The memory 1414 may store various types of information and/or instructions. The memory 1414 may store software code 1415 embodying instructions that, when executed by the processor 1413, perform the operations of the first device 910 described throughout the disclosure of this disclosure. For example, the software code 1415 are instructions that, when executed by the processor 1413, perform functions, procedures, and/or methods of the first device 1410 described throughout the disclosure of this disclosure. It can store software code 1415 that implements. For example, the software code 1415 can control the processor 1413 to perform one or more protocols. For example, the software code 1415 may control the processor 1413 to perform one or more layers of the air interface protocol.

The second device 1420 may include at least one transceiver such as the transceiver 1421 and at least one processing chip such as the processing chip 1422 . The processing chip 1422 may include at least one processor such as a processor 1423 and at least one memory such as a memory 1424 . The memory may be operably coupled to the processor 1423. The memory 1424 may store various types of information and/or instructions. The memory 1424 may include software code 1425 embodying instructions that, when executed by the processor 1423, perform the operations of the second device 1420 described throughout the disclosure of this disclosure. can For example, the software code 1425, when executed by the processor 1423, may be used to perform functions, procedures, and/or methods of the second device 1420 described throughout the disclosure of this disclosure. command can be implemented. For example, software code 1425 may control the processor 1423 to perform one or more protocols. For example, the software code 1425 may control the processor 1423 to perform one or more air interface protocol layers.

According to various embodiments, the first device 1410 illustrated in FIG. 14 may include a wireless device. The wireless device may include a transceiver 1411 and a processing chip 1412 . The processing chip 1412 may include a processor 1413 and memory 1414 . Memory 1414 may be functionally coupled to processor 1413. Memory 1414 may store various types of information and/or instructions. Memory 1414 may store software code 1414 embodying instructions that perform steps when executed by processor 1413 . The steps include: receiving information related to the service time of a neighboring cell; obtaining cell quality of the neighboring cell based on measurements of the neighboring cell; determining a time from a current point in time to an end point of the service time of the neighbor cell as the remaining service time of the neighbor cell; and performing cell reselection for the neighboring cell based on the cell quality of the neighboring cell and the remaining service time for the neighboring cell.

According to various embodiments, a non-transitory computer readable medium stores a plurality of instructions, which when executed by a processor of a wireless device cause the wireless device to perform steps, the steps comprising: : Receiving information related to a service time of a neighboring cell; obtaining cell quality of the neighboring cell based on measurements of the neighboring cell; determining a time from a current point in time to an end point of the service time of the neighbor cell as the remaining service time of the neighbor cell; and performing cell reselection for the neighboring cell based on the cell quality of the neighboring cell and the remaining service time for the neighboring cell.

The present disclosure may be applied to various future technologies such as AI, robotics, unmanned/autonomous vehicles, and/or augmented reality (XR).

<AI>

AI refers to artificial intelligence and/or research methodologies for creating it. Machine learning is a field of research methodology that defines and solves various problems addressed by AI. Machine learning can be defined as an algorithm that improves the performance of a task through continuous experience of a task.

An artificial neural network (ANN) is a model used in machine learning. This may mean an entire model with problem-solving ability composed of artificial neurons (nodes) forming a network of synapses. An ANN may be defined by a connection pattern between neurons in different layers, a learning process to update model parameters, and/or an activation function to generate output values. An ANN may include an input layer, an output layer, and optionally one or more hidden layers. Each layer may include one or more neurons, and the ANN may include neurons and synapses connecting the neurons. In an ANN, each neuron can output a sum, weight, and bias input of an activation function for an input signal through a synapse. The model parameter is a parameter determined through learning, and includes a neuron bias and/or a synaptic connection weight. Hyperparameters refer to parameters to be set in the machine learning algorithm prior to learning, and include learning rate, number of iterations, minimum batch size, initialization function, and the like. The purpose of training an ANN can be seen as determining the model parameters that minimize the loss function. The loss function can be used as an indicator to determine optimal model parameters in the learning process of ANNs.

Machine learning can be divided into supervised learning, unsupervised learning, and reinforcement learning according to learning methods. Supervised learning is a method of training an ANN with labels given to training data. Labels are answers (or output values) that the ANN should infer when training data is fed into the ANN. Unsupervised learning may refer to a method of training an ANN without labels given to training data. Reinforcement learning may refer to a learning method in which an agent defined in the environment learns to select an action and/or sequence of actions that maximizes a cumulative reward in each state.

When machine learning is implemented as a deep neural network (DNN) that includes multiple hidden layers among ANNs, it is also called deep learning. Deep learning is a subset of machine learning. In the description below, machine learning is used to mean deep learning.

<robot>

A robot may refer to a machine that automatically processes or operates a given task with its own capabilities. In particular, a robot having a function of recognizing the environment and performing self-determination and motion may be referred to as an intelligent robot. Robots can be classified into industrial, medical, household, military, etc. according to their purpose and field of use. The robot may include a driving unit including an actuator and/or a motor for performing various physical operations such as moving a robot joint. In addition, the mobile robot may include wheels, brakes, propellers, etc. in the drive unit, and may travel on the ground or fly in the air through the drive unit.

<Autonomous Driving>

Autonomous driving refers to autonomous driving technology, and an autonomous vehicle refers to a vehicle that drives without or with minimal user manipulation. For example, autonomous driving includes technologies that keep lanes while driving, technologies that automatically control speed, such as adaptive cruise control, technologies that automatically drive along a pre-determined route, and technologies that automatically drive when a destination is set. It may include the technology of driving by setting a route. Self-driving vehicles may include vehicles with only internal combustion engines, hybrid vehicles with internal combustion engines and electric motors, and electric vehicles with only electric motors, and may include trains as well as cars. It can be said to be a robot equipped with

<XR>

XR stands for VR, AR, and MR. VR technology provides only computer graphic (CG) images of real objects or backgrounds, AR technology provides virtually created CG images to real object images, and MR technology provides computer graphics that combine virtual objects on the screen and synthesize them. It is a skill. real world. MR technology is similar to AR technology in that it shows real and virtual objects together. However, in AR technology, virtual objects are used as a complement to real objects, whereas in MR technology, virtual and real objects are used equally. XR technology can be applied to HMDs, heads-up displays (HUDs), mobile phones, tablet PCs, laptops, desktops, TVs, and digital signage. A device to which XR technology is applied may be referred to as an XR device.

15 shows an example of an AI device to which the technical features of the present disclosure can be applied.

The AI device 1500 is a TV, projector, mobile phone, smart phone, desktop computer, laptop computer, digital broadcasting terminal, PDA, PMP, navigation device, tablet PC, wearable device, set-top box (STB), digital multimedia broadcasting (DMB) It may be implemented as a static or portable device such as a receiver, radio, washing machine, refrigerator, digital signage, robot, vehicle, and the like.

Referring to FIG. 15 , the AI device 1500 includes a communication unit 1510, an input unit 1520, a learning processor 1530, a transmission unit 1540, an output unit 1550, a memory 1560, and a processor 1570. ) may be included.

The communication unit 1510 may transmit and/or receive data from an AI device and an external device such as an AI server using a wired and/or wireless communication technology. For example, the communication unit 1510 may transmit and/or receive sensor information, a user input, a learning model, and a control signal by an external device. The communication technology used by the communication unit 1510 includes Global System for Mobile Communications (GSM), Code Division Multiple Access (CDMA), LTE/LTE-A, 5G, WLAN, Wi-Fi, Bluetooth ^TM , may include radio frequency identification (RFID), infrared data connection (IrDA), ZigBee, and/or near field communication (NFC).

The input unit 1520 may acquire various types of data. The input unit 1520 may include a camera for inputting a video signal, a microphone for receiving an audio signal, and a user input unit for receiving information from a user. A camera and/or microphone may be treated as a sensor, and a signal obtained from the camera and/or microphone may be referred to as data and/or sensor information. The input unit 1520 may obtain input data to be used when obtaining an output using the learning data and the learning model. The input unit 1520 may obtain raw input data, and in this case, the processor 1570 or the learning processor 1530 may extract features by pre-processing the input data.

The learning processor 1530 may learn a model composed of ANNs using training data. An ANN trained in this way can be called a learning model. The learning model may be used to infer a result value for new input data rather than learning data, and this inferred value may be used as a basis for determining what action to perform. The learning processor 1530 may perform AI processing together with the learning processor of the AI server. The learning processor 1530 may include a memory integrated and/or implemented in the AI device 1500. Alternatively, the learning processor 1530 may be implemented using the memory 1560, an external memory directly connected to the AI device 1500, and/or a memory maintained in an external device.

The sensing unit 1540 may obtain internal information of at least one AI device 1500, environment information of the AI device 1500, and/or user information using various sensors. Sensors included in the sensing unit 1540 include a proximity sensor, an illuminance sensor, an acceleration sensor, a magnetic sensor, a gyro sensor, an inertial sensor, an RGB sensor, an IR sensor, a fingerprint recognition sensor, an ultrasonic sensor, an optical sensor, a microphone, a light detection and range detection (LIDAR), and/or radar.

The output unit 1550 may generate output related to visual, auditory, and tactile sensations. The output unit 1550 may include a display unit for outputting visual information, a speaker for outputting auditory information, and/or a haptic module for outputting tactile information.

The memory 1560 may store data supporting various functions of the AI device 1500 . For example, the memory 1560 may store input data acquired by the input unit 1520, learning data, a learning model, a learning history, and the like.

The processor 1570 may determine at least one executable operation of the AI device 1500 based on information determined and/or generated using a data analysis algorithm and/or a machine learning algorithm. The processor 1570 may control components of the AI device 1500 to perform the determined operation again. The processor 1570 may request, query, receive, and/or utilize data from the processor 1530 and/or the memory 1560, and may determine a predicted action and/or a desired one of the at least one executable action. Components of the AI device 1500 may be controlled to execute actions. The processor 1570 may generate a control signal for controlling an external device, and may transmit the generated control signal to an external device when a secondary device needs to be linked to perform a determined operation. The processor 1570 may obtain information related to intention with respect to the user input and determine a user's request based on the obtained information related to intention. The processor 1570 is a speech-to-text (STT) engine for converting at least one speech input into a text string to obtain information related to an intent corresponding to a user input and/or a natural language intent A natural language processing (NLP) engine for obtaining information related to may be used. The at least one STT engine and/or NLP engine may be configured as an ANN, at least some of which are trained according to a machine learning algorithm. At least one STT engine and/or NLP engine may be learned by the learning processor 1530, learned by the learning processor of the AI server, or learned by distributed processing. The processor 1570 may collect history information including a user's feedback on operation content and/or operation of the AI device 1500, and the like. The processor 1570 may store the collected history information in the memory 1560 and/or the learning processor 1530 and/or transmit it to an external device such as an AI server. The collected history information may be used to update the learning model. The processor 1570 may control at least some of the components of the AI device 1500 to drive an application program stored in the memory 1560 . Also, the processor 1570 may operate two or more components included in the AI device 1500 by combining each component for driving an application program.

16 shows an example of an AI system to which the technical features of the present disclosure can be applied.

Referring to FIG. 16, in the AI system, at least one AI server 1620, a robot 1610a, an autonomous vehicle 1610b, an XR device 1610c, a smartphone 1610d, and/or a home appliance 1610e ) is connected to the cloud network 1600. These robots 1610a, unmanned vehicles 1610b, XR devices 1610c, smart phones 1610d, and/or home appliances 1610e to which AI technology is applied may be referred to as AI devices 1610a to 1610e.

The cloud network 1600 may refer to a network forming part of the cloud computing infrastructure and/or a network existing inside the cloud computing infrastructure. The cloud network 1600 may be configured using a 3G network, a 4G or LTE network, and/or a 5G network. That is, each of the devices 1610a to 1610e and 1620 constituting the AI system may be interconnected through the cloud network 1600 . In particular, each of devices 1610a through 1610e and 1620 may communicate with each other through a base station, but may communicate directly with each other without using a base station.

The AI server 1620 may include a server for performing AI processing and a server for performing work on big data. The AI server 1620 connects at least one or more AI devices constituting the AI system through the cloud network 1600, that is, the robot 1610a, the self-driving vehicle 1610b, and the XR device 1610c. , It is connected to the smartphone 1610d and/or the home appliance 1610e and may process at least a part of AI processing of the connected AI devices 1610a to 1610e. The AI server 1620 may learn an ANN according to a machine learning algorithm instead of the AI devices 1610a to 1610e, and directly store and/or transmit a learning model to the AI devices 1610a to 1610e. can The AI server 1620 receives input data from the AI devices 1610a to 1610e, infers result values for the received input data using the learning model, and reacts and responds based on the inferred result values. / Or a control command may be generated, and the generated data may be transmitted to the AI devices 1610a to 1610e. Alternatively, the AI devices 1610a to 1610e may directly infer result values for input data using a learning model, and generate reactions and/or control commands based on the inferred result values. .

Various embodiments of the AI devices 1610a to 1610e to which the technical features of the present disclosure may be applied will be described. The AI devices 1610a to 1610e shown in FIG. 16 may be regarded as specific embodiments of the AI device 1500 shown in FIG. 15 .

The present disclosure may have various beneficial effects.

For example, the UE does not always perform cell reselection to a cell with the best cell quality. Only a cell with a remaining service time longer than the threshold may be a candidate cell for cell reselection. Alternatively, among cells whose cell quality is higher than the threshold value, the UE performs cell reselection to a cell having the longest remaining service time. Accordingly, the UE may perform cell reselection on a cell having a long remaining service time in order to prevent frequent cell reselection.

In view of the example systems described in this disclosure, methodologies that may be implemented in accordance with the subject matter of this disclosure have been described with reference to several flow diagrams. For simplicity of explanation, these methodologies are shown and described as a series of steps or blocks; it should be understood and appreciated that the claimed subject matter is not limited by the order of such steps or blocks, and some steps may be different from one another. may occur in sequence or may be performed concurrently with other steps depicted and described in this disclosure. In addition, those skilled in the art will understand that the steps illustrated in the flow chart are not exclusive and other steps may be included or one or more steps from the flow chart may be deleted without affecting the scope of the present disclosure. you will be able to understand

The claims in this disclosure can be combined in a variety of ways. For example, technical features in method claims of the present disclosure may be combined to be implemented or performed in an apparatus, and technical features in apparatus claims may be combined to be implemented or performed in a method. Also, the technical features in the method claims and apparatus claims may be combined to be implemented or performed in an apparatus. Also, the technical features in the method claims and apparatus claims may be combined to be implemented or carried out in a method. Other implementations are within the scope of the following claims.

Claims (18)

A method performed by a wireless device in a wireless communication system,
Receiving information related to a service time of a neighboring cell;
obtaining cell quality of the neighboring cell based on measurements of the neighboring cell;
determining a time from a current point in time to an end point of the service time of the neighbor cell as the remaining service time of the neighbor cell; and
and performing cell reselection for the neighboring cell based on the cell quality of the neighboring cell and the remaining service time for the neighboring cell. The method of claim 1, wherein the service time of the neighboring cell is
a period during which the wireless device is serviced by the entity in the service area of the entity associated with the neighboring cell;
a period during which the wireless device may camp on the neighboring cell in an idle mode or an inactive mode; or
Period during which the wireless device may perform a mobility or random access procedure in connected mode
A method comprising at least one of 3. The method of claim 2, wherein the service area includes at least one of a coverage area of the neighboring cell or an area bounded by a field of view of the entity. The method of claim 1, wherein the information related to the service time of the neighbor cell includes at least one of a start time of the service time of the neighbor cell and an end time of the service time of the neighbor cell. The method of claim 1, wherein the information related to the service time of the neighbor cell includes a timer value corresponding to the service time of the neighbor cell. According to claim 5,
starting a timer having the timer value immediately after receiving information related to service time of the neighbor cell; and
Determining the remaining time of the timer as a value obtained by subtracting a timer elapsed time from a time when the timer started to a current point in time from the timer value,
and the remaining service time for the neighboring cell corresponds to the remaining time of the timer. According to claim 1,
determining a neighboring cell for cell reselection from among the neighboring cells based on a corresponding cell quality for each of the neighboring cells and a corresponding remaining service time for each of the neighboring cells. 8. The method of claim 7, wherein the neighboring cells include one or more unbarred neighboring cells whose remaining service time is greater than or equal to a barring threshold set by the network. The method of claim 7, wherein determining a neighboring cell for cell reselection comprises:
determining one or more neighboring cells having cell quality higher than a cell quality threshold set by a network from among the neighboring cells; and
And determining a neighbor cell having the longest remaining service time among the one or more neighbor cells. The method of claim 7, wherein determining a neighboring cell for cell reselection comprises:
determining one or more neighboring cells having a longer remaining service time than a remaining service time threshold set by a network from among the neighboring cells; and
And determining a neighbor cell having the highest cell quality among the one or more neighbor cells. The method of claim 1, wherein the cell quality of the neighboring cell includes at least one of a cell selection reception (RX) level value of the neighboring cell, a cell selection quality value of the neighboring cell, or a cell rank value for the neighboring cell. How to. The method of claim 1 , wherein the neighbor cell comprises a Non-Terrestrial Network (NTN) cell. The method of claim 1 , wherein the wireless device communicates with at least one of a user equipment other than the wireless device, a network, and/or an autonomous vehicle. In a wireless device in a wireless communication system,
transceiver;
Memory; and
at least one processor functionally coupled to the transceiver and the memory, the at least one processor comprising:
Controlling the transceiver to receive information related to a service time of a neighboring cell;
Obtain cell quality of the neighboring cell based on measurements of the neighboring cell;
Determine the time from the current point in time to the end point of the service time of the neighbor cell as the remaining service time of the neighbor cell;
and perform cell reselection for the neighboring cell based on the cell quality of the neighboring cell and the remaining service time for the neighboring cell. A processor for a wireless device in a wireless communication system, wherein a memory of the wireless device stores software code embodying instructions that, when executed by the processor, perform operations comprising:
Receiving information related to a service time of a neighboring cell;
obtaining cell quality of the neighboring cell based on the measurement of the neighboring cell;
determining a time from a current point in time to an end point in the service time of the neighbor cell as the remaining service time of the neighbor cell; and
and performing cell reselection for the neighboring cell based on the cell quality of the neighboring cell and the remaining service time for the neighboring cell. A non-transitory computer-readable medium (CRM) storing a plurality of instructions, wherein the plurality of instructions, when executed by a processor of the wireless device, causes the wireless device to:
Receive information related to the service time of neighboring cells;
Obtain cell quality of the neighboring cell based on measurements of the neighboring cell;
Determine the time from the current point in time to the end point of the service time of the neighbor cell as the remaining service time of the neighbor cell;
A non-transitory computer readable medium configured to perform cell reselection for a neighboring cell based on the cell quality of the neighboring cell and the remaining service time for the neighboring cell. In a method performed by an entity associated with a serving cell in a wireless communication system,
performing a random access procedure with a wireless device;
establishing a connection with the wireless device; and
Transmitting information related to a service time of a neighboring cell to the wireless device;
The wireless device performs cell reselection from the serving cell to the neighboring cell based on the cell quality of the neighboring cell and the remaining service time for the neighboring cell;
The remaining service time of the neighbor cell is determined as a time from a current point in time to an end point of the service time of the neighbor cell. In an entity related to a serving cell in a wireless communication system,
transceiver;
Memory; and
at least one processor functionally coupled to the transceiver and the memory, the at least one processor comprising:
performing a random access procedure with a wireless device;
establish a connection with the wireless device;
configured to control the transceiver to transmit information related to a service time of a neighboring cell to the wireless device;
The wireless device performs cell reselection from the serving cell to the neighboring cell based on the cell quality of the neighboring cell and the remaining service time for the neighboring cell;
The remaining service time of the neighboring cell is determined as a time from a current point in time to an end point of the service time of the neighboring cell.

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