WO2025154993A1

WO2025154993A1 - Method and apparatus for lower layer triggered mobility in a wireless network system

Info

Publication number: WO2025154993A1
Application number: PCT/KR2024/096485
Authority: WO
Inventors: Daewook BYUN; Siyoung Choi; Jaemin HAN; Seokjung KIM
Original assignee: LG Electronics Inc
Current assignee: LG Electronics Inc
Priority date: 2024-01-19
Filing date: 2024-11-13
Publication date: 2025-07-24
Anticipated expiration: 2026-07-19

Abstract

A method and apparatus for lower layer triggered mobility in a wireless network system is provided. The method comprises: transmitting, by the wireless device to the source DU, a measurement report; receiving, by the wireless device from the source DU, a cell switch command for an LTM to a candidate DU of the RAN node; performing, by the wireless device, a RACH-based LTM to the candidate DU; and transmitting, by the wireless device to the CU via the candidate DU, a message including (i) information related to TA measurements and/or (ii) information related to the RACH-based LTM.

Description

METHOD AND APPARATUS FOR LOWER LAYER TRIGGERED MOBILITY IN A WIRELESS NETWORK SYSTEM

The present disclosure relates to a method and apparatus for lower layer triggered mobility in a wireless network system.

3rd generation partnership project (3GPP) long-term evolution (LTE) is a technology for enabling high-speed packet communications. Many schemes have been proposed for the LTE objective including those that aim to reduce user and provider costs, improve service quality, and expand and improve coverage and system capacity. The 3GPP LTE requires reduced cost per bit, increased service availability, flexible use of a frequency band, a simple structure, an open interface, and adequate power consumption of a terminal as an upper-level requirement.

Work has started in international telecommunication union (ITU) and 3GPP to develop requirements and specifications for new radio (NR) systems. 3GPP has to identify and develop the technology components needed for successfully standardizing the new RAT timely satisfying both the urgent market needs, and the more long-term requirements set forth by the ITU radio communication sector (ITU-R) international mobile telecommunications (IMT)-2020 process. Further, the NR should be able to use any spectrum band ranging at least up to 100 GHz that may be made available for wireless communications even in a more distant future.

The NR targets a single technical framework addressing all usage scenarios, requirements and deployment scenarios including enhanced mobile broadband (eMBB), massive machine-type-communications (mMTC), ultra-reliable and low latency communications (URLLC), etc. The NR shall be inherently forward compatible.

In NR, based on the measurement report provided by the UE, the gNB-CU determines the Lower layer Triggered Mobility (LTM). The UE can be configured UE-based timing advance (TA) measurement for the candidate target cell by the gNB-CU. Based on the configuration related to the received UE-based TA measurement, the UE performs TA measurement to obtain a suitable TA.

In a situation where the candidate target cells are densely deployed, if the UE moves fast, the UE may receive the Cell Switch Command from the source gNB-DU even before the UE obtains the appropriate TA for the candidate target cells.

After receiving the Cell Switch Command, the UE may perform RACH-less LTM without having a suitable TA value or RACH-based LTM. When performing RACH-less LTM, there may be a problem in connecting to the target cell due to the lack of a suitable TA value. When performing RACH-based LTM, there may be no problem in connecting to the target cell, but it may take a long time to perform LTM.

Therefore, studies for lower layer triggered mobility in a wireless network system are required.

In an aspect, a method is provided. The method comprises: receiving, by a wireless device from a CU of a RAN node via a source DU of the RAN node, a LTM configuration; transmitting, by the wireless device to the source DU, a measurement report; receiving, by the wireless device from the source DU, a cell switch command for an LTM to a candidate DU of the RAN node; performing, by the wireless device, a RACH-based LTM to the candidate DU; and transmitting, by the wireless device to the CU via the candidate DU, a message including (i) information related to TA measurements and/or (ii) information related to the RACH-based LTM.

In another aspect, an apparatus for implementing the above method is provided.

The present disclosure can have various advantageous effects.

According to some embodiments of the present disclosure, the wireless device could efficiently perform the LTM considering UE-based TA measurement.

For example, in the inter/intra-gNB-DU LTM situation, UEs configured with UE-based TA measurement can report information related to TA measurement to the gNB-CU. Based on the information, the gNB-CU can transmit, to the UE, configuration or reconfiguration of UE-based TA measurement for the candidate target cell. Therefore, the UE can obtain a suitable TA before receiving the Cell Switch Command based on the configuration or the reconfiguration. That is, the UE configured with UE-based TA measurement for the candidate target cell can perform LTM without any problem and can be provided with uninterrupted service even during handover.

In other words, according to some embodiments of the present disclosure, based on the received UE-based TA measurements, the CU can efficiently provide reconfiguration to the UE.

According to some embodiments of the present disclosure, the wireless network system could provide efficient solutions for supporting LTM considering UE-based TA measurement.

Advantageous effects which can be obtained through specific embodiments of the present disclosure are not limited to the advantageous effects listed above. For example, there may be a variety of technical effects that a person having ordinary skill in the related art can understand and/or derive from the present disclosure. Accordingly, the specific effects of the present disclosure are not limited to those explicitly described herein, but may include various effects that may be understood or derived from the technical features of the present disclosure.

FIG. 1 shows an example of a communication system to which implementations of the present disclosure is applied.

FIG. 2 shows an example of wireless devices to which implementations of the present disclosure is applied.

FIG. 3 shows an example of a wireless device to which implementations of the present disclosure is applied.

FIG. 4 shows an example of UE to which implementations of the present disclosure is applied.

FIGS. 5 and 6 show an example of protocol stacks in a 3GPP based wireless communication system to which implementations of the present disclosure is applied.

FIG. 7 shows an example of the overall architecture of an NG-RAN to which technical features of the present disclosure can be applied.

FIG. 8 shows an interface protocol structure for F1-C to which technical features of the present disclosure can be applied.

FIG. 9 shows an example of UE information procedure.

FIG. 10 shows an example of Signalling procedure for LTM.

FIG. 11a, FIG. 11b, and FIG. 11c show an example of a flow chart for inter-gNB-DU LTM for intra-NR.

FIG. 12 shows an example of a method for lower layer triggered mobility in a wireless network system, according to some embodiments of the present disclosure.

FIG. 13a, FIG. 13b, and FIG. 13c show a flow chart for SON support of UE which UE-based TA measurement is configured in inter-gNB-DU LTM.

FIG. 14 shows an example of a method for MRO support for lower layer triggered mobility.

The following techniques, apparatuses, and systems may be applied to a variety of wireless multiple access systems. Examples of the multiple access systems include a code division multiple access (CDMA) system, a frequency division multiple access (FDMA) system, a time division multiple access (TDMA) system, an orthogonal frequency division multiple access (OFDMA) system, a single carrier frequency division multiple access (SC-FDMA) system, and a multicarrier frequency division multiple access (MC-FDMA) system. CDMA may be embodied through radio technology such as universal terrestrial radio access (UTRA) or CDMA2000. TDMA may be embodied through radio technology such as global system for mobile communications (GSM), general packet radio service (GPRS), or enhanced data rates for GSM evolution (EDGE). OFDMA may be embodied through radio technology such as institute of electrical and electronics engineers (IEEE) 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802.20, or evolved UTRA (E-UTRA). UTRA is a part of a universal mobile telecommunications system (UMTS). 3rd generation partnership project (3GPP) long term evolution (LTE) is a part of evolved UMTS (E-UMTS) using E-UTRA. 3GPP LTE employs OFDMA in DL and SC-FDMA in UL. Evolution of 3GPP LTE includes LTE-A (advanced), LTE-A Pro, and/or 5G NR (new radio).

For convenience of description, implementations of the present disclosure are mainly described in regards to a 3GPP based wireless communication system. However, the technical features of the present disclosure are not limited thereto. For example, although the following detailed description is given based on a mobile communication system corresponding to a 3GPP based wireless communication system, aspects of the present disclosure that are not limited to 3GPP based wireless communication system are applicable to other mobile communication systems.

For terms and technologies which are not specifically described among the terms of and technologies employed in the present disclosure, the wireless communication standard documents published before the present disclosure may be referenced.

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

In the present disclosure, slash (/) or comma (,) may mean "and/or". For example, "A/B" may 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 the present disclosure, "at least one of A and B" may mean "only A", "only B" or "both A and B". In addition, the expression "at least one of A or B" or "at least one of A and/or B" in the present disclosure may be interpreted as same as "at least one of A and B".

In addition, in the present disclosure, "at least one of A, B and C" may mean "only A", "only B", "only C", or "any combination of A, B and C". In addition, "at least one of A, B or C" or "at least one of A, B and/or C" may mean "at least one of A, B and C".

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

Technical features that are separately described in one drawing in the present disclosure may be implemented separately or simultaneously.

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

Hereinafter, the present disclosure will be described in more detail with reference to drawings. The same reference numerals in the following drawings and/or descriptions may refer to the same and/or corresponding hardware blocks, software blocks, and/or functional blocks unless otherwise indicated.

The 5G usage scenarios shown in FIG. 1 are only exemplary, and the technical features of the present disclosure can be applied to other 5G usage scenarios which are not shown in FIG. 1.

Three main requirement categories for 5G include (1) a category of enhanced mobile broadband (eMBB), (2) a category of massive machine type communication (mMTC), and (3) a category of ultra-reliable and low latency communications (URLLC).

Partial use cases may require a plurality of categories for optimization and other use cases may focus only upon one key performance indicator (KPI). 5G supports such various use cases using a flexible and reliable method.

eMBB far surpasses basic mobile Internet access and covers abundant bidirectional work and media and entertainment applications in cloud and augmented reality. Data is one of 5G core motive forces and, in a 5G era, a dedicated voice service may not be provided for the first time. In 5G, it is expected that voice will be simply processed as an application program using data connection provided by a communication system. Main causes for increased traffic volume are due to an increase in the size of content and an increase in the number of applications requiring high data transmission rate. A streaming service (of audio and video), conversational video, and mobile Internet access will be more widely used as more devices are connected to the Internet. These many application programs require connectivity of an always turned-on state in order to push real-time information and alarm for users. Cloud storage and applications are rapidly increasing in a mobile communication platform and may be applied to both work and entertainment. The cloud storage is a special use case which accelerates growth of uplink data transmission rate. 5G is also used for remote work of cloud. When a tactile interface is used, 5G demands much lower end-to-end latency to maintain user good experience. Entertainment, for example, cloud gaming and video streaming, is another core element which increases demand for mobile broadband capability. Entertainment is essential for a smartphone and a tablet in any place including high mobility environments such as a train, a vehicle, and an airplane. Other use cases are augmented reality for entertainment and information search. In this case, the augmented reality requires very low latency and instantaneous data volume.

In addition, one of the most expected 5G use cases relates a function capable of smoothly connecting embedded sensors in all fields, i.e., mMTC. It is expected that the number of potential Internet-of-things (IoT) devices will reach 204 hundred million up to the year of 2020. An industrial IoT is one of categories of performing a main role enabling a smart city, asset tracking, smart utility, agriculture, and security infrastructure through 5G.

URLLC includes a new service that will change industry through remote control of main infrastructure and an ultra-reliable/available low-latency link such as a self-driving vehicle. A level of reliability and latency is essential to control a smart grid, automatize industry, achieve robotics, and control and adjust a drone.

5G is a means of providing streaming evaluated as a few hundred megabits per second to gigabits per second and may complement fiber-to-the-home (FTTH) and cable-based broadband (or DOCSIS). Such fast speed is needed to deliver TV in resolution of 4K or more (6K, 8K, and more), as well as virtual reality and augmented reality. Virtual reality (VR) and augmented reality (AR) applications include almost immersive sports games. A specific application program may require a special network configuration. For example, for VR games, gaming companies need to incorporate a core server into an edge network server of a network operator in order to minimize latency.

Automotive is expected to be a new important motivated force in 5G together with many use cases for mobile communication for vehicles. For example, entertainment for passengers requires high simultaneous capacity and mobile broadband with high mobility. This is because future users continue to expect connection of high quality regardless of their locations and speeds. Another use case of an automotive field is an AR dashboard. The AR dashboard causes a driver to identify an object in the dark in addition to an object seen from a front window and displays a distance from the object and a movement of the object by overlapping information talking to the driver. In the future, a wireless module enables communication between vehicles, information exchange between a vehicle and supporting infrastructure, and information exchange between a vehicle and other connected devices (e.g., devices accompanied by a pedestrian). A safety system guides alternative courses of a behavior so that a driver may drive more safely drive, thereby lowering the danger of an accident. The next stage will be a remotely controlled or self-driven vehicle. This requires very high reliability and very fast communication between different self-driven vehicles and between a vehicle and infrastructure. In the future, a self-driven vehicle will perform all driving activities and a driver will focus only upon abnormal traffic that the vehicle cannot identify. Technical requirements of a self-driven vehicle demand ultra-low latency and ultra-high reliability so that traffic safety is increased to a level that cannot be achieved by human being.

A smart city and a smart home/building mentioned as a smart society will be embedded in a high-density wireless sensor network. A distributed network of an intelligent sensor will identify conditions for costs and energy-efficient maintenance of a city or a home. Similar configurations may be performed for respective households. All of temperature sensors, window and heating controllers, burglar alarms, and home appliances are wirelessly connected. Many of these sensors are typically low in data transmission rate, power, and cost. However, real-time HD video may be demanded by a specific type of device to perform monitoring.

Consumption and distribution of energy including heat or gas is distributed at a higher level so that automated control of the distribution sensor network is demanded. The smart grid collects information and connects the sensors to each other using digital information and communication technology so as to act according to the collected information. Since this information may include behaviors of a supply company and a consumer, the smart grid may improve distribution of fuels such as electricity by a method having efficiency, reliability, economic feasibility, production sustainability, and automation. The smart grid may also be regarded as another sensor network having low latency.

Mission critical application (e.g., e-health) is one of 5G use scenarios. A health part contains many application programs capable of enjoying benefit of mobile communication. A communication system may support remote treatment that provides clinical treatment in a faraway place. Remote treatment may aid in reducing a barrier against distance and improve access to medical services that cannot be continuously available in a faraway rural area. Remote treatment is also used to perform important treatment and save lives in an emergency situation. The wireless sensor network based on mobile communication may provide remote monitoring and sensors for parameters such as heart rate and blood pressure.

Wireless and mobile communication gradually becomes important in the field of an industrial application. Wiring is high in installation and maintenance cost. Therefore, a possibility of replacing a cable with reconstructible wireless links is an attractive opportunity in many industrial fields. However, in order to achieve this replacement, it is necessary for wireless connection to be established with latency, reliability, and capacity similar to those of the cable and management of wireless connection needs to be simplified. Low latency and a very low error probability are new requirements when connection to 5G is needed.

Logistics and freight tracking are important use cases for mobile communication that enables inventory and package tracking anywhere using a location-based information system. The use cases of logistics and freight typically demand low data rate but require location information with a wide range and reliability.

Referring to FIG. 1, the communication system 1 includes wireless devices 100a to 100f, base stations (BSs) 200, and a network 300. Although FIG. 1 illustrates a 5G network as an example of the network of the communication system 1, the implementations of the present disclosure are not limited to the 5G system, and can be applied to the future communication system beyond the 5G system.

The BSs 200 and the network 300 may be implemented as wireless devices and a specific wireless device may operate as a BS/network node with respect to other wireless devices.

The wireless devices 100a to 100f represent devices performing communication using radio access technology (RAT) (e.g., 5G new RAT (NR)) or LTE) and may be referred to as communication/radio/5G devices. The wireless devices 100a to 100f may include, without being limited to, a robot 100a, vehicles 100b-1 and 100b-2, an extended reality (XR) device 100c, a hand-held device 100d, a home appliance 100e, an IoT device 100f, and an artificial intelligence (AI) device/server 400. For example, the vehicles may include a vehicle having a wireless communication function, an autonomous driving vehicle, and a vehicle capable of performing communication between vehicles. The vehicles may include an unmanned aerial vehicle (UAV) (e.g., a drone). The XR device may include an AR/VR/Mixed Reality (MR) device and may be implemented in the form of a head-mounted device (HMD), a head-up display (HUD) mounted in a vehicle, a television, a smartphone, a computer, a wearable device, a home appliance device, a digital signage, a vehicle, a robot, etc. The hand-held device may include a smartphone, a smartpad, a wearable device (e.g., a smartwatch or a smartglasses), and a computer (e.g., a notebook). The home appliance may include a TV, a refrigerator, and a washing machine. The IoT device may include a sensor and a smartmeter.

In the present disclosure, the wireless devices 100a to 100f may be called user equipments (UEs). A UE may include, for example, a cellular phone, a smartphone, a laptop computer, a digital broadcast terminal, a personal digital assistant (PDA), a portable multimedia player (PMP), a navigation system, a slate personal computer (PC), a tablet PC, an ultrabook, a vehicle, a vehicle having an autonomous traveling function, a connected car, an UAV, an AI module, a robot, an AR device, a VR device, an MR device, a hologram device, a public safety device, an MTC device, an IoT device, a medical device, a FinTech device (or a financial device), a security device, a weather/environment device, a device related to a 5G service, or a device related to a fourth industrial revolution field.

The UAV may be, for example, an aircraft aviated by a wireless control signal without a human being onboard.

The VR device may include, for example, a device for implementing an object or a background of the virtual world. The AR device may include, for example, a device implemented by connecting an object or a background of the virtual world to an object or a background of the real world. The MR device may include, for example, a device implemented by merging an object or a background of the virtual world into an object or a background of the real world. The hologram device may include, for example, a device for implementing a stereoscopic image of 360 degrees by recording and reproducing stereoscopic information, using an interference phenomenon of light generated when two laser lights called holography meet.

The public safety device may include, for example, an image relay device or an image device that is wearable on the body of a user.

The MTC device and the IoT device may be, for example, devices that do not require direct human intervention or manipulation. For example, the MTC device and the IoT device may include smartmeters, vending machines, thermometers, smartbulbs, door locks, or various sensors.

The medical device may be, for example, a device used for the purpose of diagnosing, treating, relieving, curing, or preventing disease. For example, the medical device may be a device used for the purpose of diagnosing, treating, relieving, or correcting injury or impairment. For example, the medical device may be a device used for the purpose of inspecting, replacing, or modifying a structure or a function. For example, the medical device may be a device used for the purpose of adjusting pregnancy. For example, the medical device may include a device for treatment, a device for operation, a device for (in vitro) diagnosis, a hearing aid, or a device for procedure.

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

The FinTech device may be, for example, a device capable of providing a financial service such as mobile payment. For example, the FinTech device may include a payment device or a point of sales (POS) system.

The weather/environment device may include, for example, a device for monitoring or predicting a weather/environment.

The wireless devices 100a to 100f may be connected to the network 300 via the BSs 200. An AI technology may be applied to the wireless devices 100a to 100f and the wireless devices 100a to 100f may be connected to the AI server 400 via the network 300. The network 300 may be configured using a 3G network, a 4G (e.g., LTE) network, a 5G (e.g., NR) network, and a beyond-5G network. Although the wireless devices 100a to 100f may communicate with each other through the BSs 200/network 300, the wireless devices 100a to 100f may perform direct communication (e.g., sidelink communication) with each other without passing through the BSs 200/network 300. For example, the vehicles 100b-1 and 100b-2 may perform direct communication (e.g., vehicle-to-vehicle (V2V)/vehicle-to-everything (V2X) communication). The IoT device (e.g., a sensor) may perform direct communication with other IoT devices (e.g., sensors) or other wireless devices 100a to 100f.

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

AI refers to the field of studying artificial intelligence or the methodology that can create it, and machine learning refers to the field of defining various problems addressed in the field of AI and the field of methodology to solve them. Machine learning is also defined as an algorithm that increases the performance of a task through steady experience on a task.

Robot means a machine that automatically processes or operates a given task by its own ability. In particular, robots with the ability to recognize the environment and make self-determination to perform actions can be called intelligent robots. Robots can be classified as industrial, medical, home, military, etc., depending on the purpose or area of use. The robot can perform a variety of physical operations, such as moving the robot joints with actuators or motors. The movable robot also includes wheels, brakes, propellers, etc., on the drive, allowing it to drive on the ground or fly in the air.

Autonomous driving means a technology that drives on its own, and autonomous vehicles mean vehicles that drive without user's control or with minimal user's control. For example, autonomous driving may include maintaining lanes in motion, automatically adjusting speed such as adaptive cruise control, automatic driving along a set route, and automatically setting a route when a destination is set. The vehicle covers vehicles equipped with internal combustion engines, hybrid vehicles equipped with internal combustion engines and electric motors, and electric vehicles equipped with electric motors, and may include trains, motorcycles, etc., as well as cars. Autonomous vehicles can be seen as robots with autonomous driving functions.

Extended reality is collectively referred to as VR, AR, and MR. VR technology provides objects and backgrounds of real world only through computer graphic (CG) images. AR technology provides a virtual CG image on top of a real object image. MR technology is a CG technology that combines and combines virtual objects into the real world. MR technology is similar to AR technology in that they show real and virtual objects together. However, there is a difference in that in AR technology, virtual objects are used as complementary forms to real objects, while in MR technology, virtual objects and real objects are used as equal personalities.

NR supports multiples numerologies (and/or multiple subcarrier spacings (SCS)) to support various 5G services. For example, if SCS is 15 kHz, wide area can be supported in traditional cellular bands, and if SCS is 30 kHz/60 kHz, dense-urban, lower latency, and wider carrier bandwidth can be supported. If SCS is 60 kHz or higher, bandwidths greater than 24.25 GHz can be supported to overcome phase noise.

The NR frequency band may be defined as two types of frequency range, i.e., FR1 and FR2. The numerical value of the frequency range may be changed. 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 ranges used in the NR system, FR1 may mean "sub 6 GHz range", FR2 may mean "above 6 GHz range," and may be referred to as millimeter wave (mmW).

Frequency Range designation	Corresponding frequency range	Subcarrier Spacing
FR1	450MHz - 6000MHz	15, 30, 60kHz
FR2	24250MHz - 52600MHz	60, 120, 240kHz

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

Frequency Range designation	Corresponding frequency range	Subcarrier Spacing
FR1	410MHz - 7125MHz	15, 30, 60kHz
FR2	24250MHz - 52600MHz	60, 120, 240kHz

Here, the radio communication technologies implemented in the wireless devices in the present disclosure may include narrowband internet-of-things (NB-IoT) technology for low-power communication as well as LTE, NR and 6G. For example, NB-IoT technology may be an example of low power wide area network (LPWAN) technology, may be implemented in specifications such as LTE Cat NB1 and/or LTE Cat NB2, and may not be limited to the above-mentioned names. Additionally and/or alternatively, the radio communication technologies implemented in the wireless devices in the present disclosure may communicate based on LTE-M technology. For example, LTE-M technology may be an example of LPWAN technology and be called by various names such as enhanced machine type communication (eMTC). For example, LTE-M technology may be implemented in at least one of the various specifications, such as 1) LTE Cat 0, 2) LTE Cat M1, 3) LTE Cat M2, 4) LTE non-bandwidth limited (non-BL), 5) LTE-MTC, 6) LTE Machine Type Communication, and/or 7) LTE M, and may not be limited to the above-mentioned names. Additionally and/or alternatively, the radio communication technologies implemented in the wireless devices in the present disclosure may include at least one of ZigBee, Bluetooth, and/or LPWAN which take into account low-power communication, and may not be limited to the above-mentioned names. For example, ZigBee technology may generate personal area networks (PANs) associated with small/low-power digital communication based on various specifications such as IEEE 802.15.4 and may be called various names.

Referring to FIG. 2, a first wireless device 100 and a second wireless device 200 may transmit/receive radio signals to/from an external device through a variety of RATs (e.g., LTE and NR).

In FIG. 2, {the first wireless device 100 and the second wireless device 200} may correspond to at least one of {the wireless device 100a to 100f and the BS 200}, {the wireless device 100a to 100f and the wireless device 100a to 100f} and/or {the BS 200 and the BS 200} of FIG. 1.

The first wireless device 100 may include at least one transceiver, such as a transceiver 106, at least one processing chip, such as a processing chip 101, and/or one or more antennas 108.

The processing chip 101 may include at least one processor, such a processor 102, and at least one memory, such as a memory 104. It is exemplarily shown in FIG. 2 that the memory 104 is included in the processing chip 101. Additional and/or alternatively, the memory 104 may be placed outside of the processing chip 101.

The processor 102 may control the memory 104 and/or the transceiver 106 and may be configured to implement the descriptions, functions, procedures, suggestions, methods and/or operational flowcharts described in the present disclosure. For example, the processor 102 may process information within the memory 104 to generate first information/signals and then transmit radio signals including the first information/signals through the transceiver 106. The processor 102 may receive radio signals including second information/signals through the transceiver 106 and then store information obtained by processing the second information/signals in the memory 104.

The memory 104 may be operably connectable to the processor 102. The memory 104 may store various types of information and/or instructions. The memory 104 may store a software code 105 which implements instructions that, when executed by the processor 102, perform the descriptions, functions, procedures, suggestions, methods and/or operational flowcharts disclosed in the present disclosure. For example, the software code 105 may implement instructions that, when executed by the processor 102, perform the descriptions, functions, procedures, suggestions, methods and/or operational flowcharts disclosed in the present disclosure. For example, the software code 105 may control the processor 102 to perform one or more protocols. For example, the software code 105 may control the processor 102 to perform one or more layers of the radio interface protocol.

Herein, the processor 102 and the memory 104 may be a part of a communication modem/circuit/chip designed to implement RAT (e.g., LTE or NR). The transceiver 106 may be connected to the processor 102 and transmit and/or receive radio signals through one or more antennas 108. Each of the transceiver 106 may include a transmitter and/or a receiver. The transceiver 106 may be interchangeably used with radio frequency (RF) unit(s). In the present disclosure, the first wireless device 100 may represent a communication modem/circuit/chip.

The second wireless device 200 may include at least one transceiver, such as a transceiver 206, at least one processing chip, such as a processing chip 201, and/or one or more antennas 208.

The processing chip 201 may include at least one processor, such a processor 202, and at least one memory, such as a memory 204. It is exemplarily shown in FIG. 2 that the memory 204 is included in the processing chip 201. Additional and/or alternatively, the memory 204 may be placed outside of the processing chip 201.

The processor 202 may control the memory 204 and/or the transceiver 206 and may be configured to implement the descriptions, functions, procedures, suggestions, methods and/or operational flowcharts described in the present disclosure. For example, the processor 202 may process information within the memory 204 to generate third information/signals and then transmit radio signals including the third information/signals through the transceiver 206. The processor 202 may receive radio signals including fourth information/signals through the transceiver 106 and then store information obtained by processing the fourth information/signals in the memory 204.

The memory 204 may be operably connectable to the processor 202. The memory 204 may store various types of information and/or instructions. The memory 204 may store a software code 205 which implements instructions that, when executed by the processor 202, perform the descriptions, functions, procedures, suggestions, methods and/or operational flowcharts disclosed in the present disclosure. For example, the software code 205 may implement instructions that, when executed by the processor 202, perform the descriptions, functions, procedures, suggestions, methods and/or operational flowcharts disclosed in the present disclosure. For example, the software code 205 may control the processor 202 to perform one or more protocols. For example, the software code 205 may control the processor 202 to perform one or more layers of the radio interface protocol.

Herein, the processor 202 and the memory 204 may be a part of a communication modem/circuit/chip designed to implement RAT (e.g., LTE or NR). The transceiver 206 may be connected to the processor 202 and transmit and/or receive radio signals through one or more antennas 208. Each of the transceiver 206 may include a transmitter and/or a receiver. The transceiver 206 may be interchangeably used with RF unit. In the present disclosure, the second wireless device 200 may represent a communication modem/circuit/chip.

Hereinafter, hardware elements of the wireless devices 100 and 200 will be described more specifically. One or more protocol layers may be implemented by, without being limited to, one or more processors 102 and 202. For example, the one or more processors 102 and 202 may implement one or more layers (e.g., functional layers such as physical (PHY) layer, media access control (MAC) layer, radio link control (RLC) layer, packet data convergence protocol (PDCP) layer, radio resource control (RRC) layer, and service data adaptation protocol (SDAP) layer). The one or more processors 102 and 202 may generate one or more protocol data units (PDUs) and/or one or more service data unit (SDUs) according to the descriptions, functions, procedures, suggestions, methods and/or operational flowcharts disclosed in the present disclosure. The one or more processors 102 and 202 may generate messages, control information, data, or information according to the descriptions, functions, procedures, suggestions, methods and/or operational flowcharts disclosed in the present disclosure. The one or more processors 102 and 202 may generate signals (e.g., baseband signals) including PDUs, SDUs, messages, control information, data, or information according to the descriptions, functions, procedures, suggestions, methods and/or operational flowcharts disclosed in the present disclosure and provide the generated signals to the one or more transceivers 106 and 206. The one or more processors 102 and 202 may receive the signals (e.g., baseband signals) from the one or more transceivers 106 and 206 and acquire the PDUs, SDUs, messages, control information, data, or information according to the descriptions, functions, procedures, suggestions, methods and/or operational flowcharts disclosed in the present disclosure.

The one or more processors 102 and 202 may be referred to as controllers, microcontrollers, microprocessors, or microcomputers. The one or more processors 102 and 202 may be implemented by hardware, firmware, software, or a combination thereof. As an example, one or more application specific integrated circuits (ASICs), one or more digital signal processors (DSPs), one or more digital signal processing devices (DSPDs), one or more programmable logic devices (PLDs), or one or more field programmable gate arrays (FPGAs) may be included in the one or more processors 102 and 202. The descriptions, functions, procedures, suggestions, methods and/or operational flowcharts disclosed in the present disclosure may be implemented using firmware or software and the firmware or software may be configured to include the modules, procedures, or functions. Firmware or software configured to perform the descriptions, functions, procedures, suggestions, methods and/or operational flowcharts disclosed in the present disclosure may be included in the one or more processors 102 and 202 or stored in the one or more memories 104 and 204 so as to be driven by the one or more processors 102 and 202. The descriptions, functions, procedures, suggestions, methods and/or operational flowcharts disclosed in the present disclosure may be implemented using firmware or software in the form of code, commands, and/or a set of commands.

The one or more memories 104 and 204 may be connected to the one or more processors 102 and 202 and store various types of data, signals, messages, information, programs, code, instructions, and/or commands. The one or more memories 104 and 204 may be configured by read-only memories (ROMs), random access memories (RAMs), electrically erasable programmable read-only memories (EPROMs), flash memories, hard drives, registers, cash memories, computer-readable storage media, and/or combinations thereof. The one or more memories 104 and 204 may be located at the interior and/or exterior of the one or more processors 102 and 202. The one or more memories 104 and 204 may be connected to the one or more processors 102 and 202 through various technologies such as wired or wireless connection.

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

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

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

In the implementations of the present disclosure, a UE may operate as a transmitting device in uplink (UL) and as a receiving device in downlink (DL). In the implementations of the present disclosure, a BS may operate as a receiving device in UL and as a transmitting device in DL. Hereinafter, for convenience of description, it is mainly assumed that the first wireless device 100 acts as the UE, and the second wireless device 200 acts as the BS. For example, the processor(s) 102 connected to, mounted on or launched in the first wireless device 100 may be configured to perform the UE behavior according to an implementation of the present disclosure or control the transceiver(s) 106 to perform the UE behavior according to an implementation of the present disclosure. The processor(s) 202 connected to, mounted on or launched in the second wireless device 200 may be configured to perform the BS behavior according to an implementation of the present disclosure or control the transceiver(s) 206 to perform the BS behavior according to an implementation of the present disclosure.

In the present disclosure, a BS is also referred to as a node B (NB), an eNode B (eNB), or a gNB.

The wireless device may be implemented in various forms according to a use-case/service (refer to FIG. 1).

Referring to FIG. 3, wireless devices 100 and 200 may correspond to the wireless devices 100 and 200 of FIG. 2 and may be configured by various elements, components, units/portions, and/or modules. For example, each of the wireless devices 100 and 200 may include a communication unit 110, a control unit 120, a memory unit 130, and additional components 140. The communication unit 110 may include a communication circuit 112 and transceiver(s) 114. For example, the communication circuit 112 may include the one or more processors 102 and 202 of FIG. 2 and/or the one or more memories 104 and 204 of FIG. 2. For example, the transceiver(s) 114 may include the one or more transceivers 106 and 206 of FIG. 2 and/or the one or more antennas 108 and 208 of FIG. 2. The control unit 120 is electrically connected to the communication unit 110, the memory unit 130, and the additional components 140 and controls overall operation of each of the wireless devices 100 and 200. For example, the control unit 120 may control an electric/mechanical operation of each of the wireless devices 100 and 200 based on programs/code/commands/information stored in the memory unit 130. The control unit 120 may transmit the information stored in the memory unit 130 to the exterior (e.g., other communication devices) via the communication unit 110 through a wireless/wired interface or store, in the memory unit 130, information received through the wireless/wired interface from the exterior (e.g., other communication devices) via the communication unit 110.

The additional components 140 may be variously configured according to types of the wireless devices 100 and 200. For example, the additional components 140 may include at least one of a power unit/battery, input/output (I/O) unit (e.g., audio I/O port, video I/O port), a driving unit, and a computing unit. The wireless devices 100 and 200 may be implemented in the form of, without being limited to, the robot (100a of FIG. 1), the vehicles (100b-1 and 100b-2 of FIG. 1), the XR device (100c of FIG. 1), the hand-held device (100d of FIG. 1), the home appliance (100e of FIG. 1), the IoT device (100f of FIG. 1), a digital broadcast terminal, a hologram device, a public safety device, an MTC device, a medicine device, a FinTech device (or a finance device), a security device, a climate/environment device, the AI server/device (400 of FIG. 1), the BSs (200 of FIG. 1), a network node, etc. The wireless devices 100 and 200 may be used in a mobile or fixed place according to a use-example/service.

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

Referring to FIG. 4, a UE 100 may correspond to the first wireless device 100 of FIG. 2 and/or the wireless device 100 or 200 of FIG. 3.

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

The processor 102 may be configured to implement the descriptions, functions, procedures, suggestions, methods and/or operational flowcharts disclosed in the present disclosure. The processor 102 may be configured to control one or more other components of the UE 100 to implement the descriptions, functions, procedures, suggestions, methods and/or operational flowcharts disclosed in the present disclosure. Layers of the radio interface protocol may be implemented in the processor 102. The processor 102 may include ASIC, other chipset, logic circuit and/or data processing device. The processor 102 may be an application processor. The processor 102 may include at least one of a digital signal processor (DSP), a central processing unit (CPU), a graphics processing unit (GPU), a modem (modulator and demodulator). An example of the processor 102 may be found in SNAPDRAGON^TM series of processors made by Qualcomm^®, EXYNOS^TM series of processors made by Samsung^®, A series of processors made by Apple^®, HELIO^TM series of processors made by MediaTek^®, ATOM^TM series of processors made by Intel^® or a corresponding next generation processor.

The memory 104 is operatively coupled with the processor 102 and stores a variety of information to operate the processor 102. The memory 104 may include ROM, RAM, flash memory, memory card, storage medium and/or other storage device. When the embodiments are implemented in software, the techniques described herein can be implemented with modules (e.g., procedures, functions, etc.) that perform the descriptions, functions, procedures, suggestions, methods and/or operational flowcharts disclosed in the present disclosure. The modules can be stored in the memory 104 and executed by the processor 102. The memory 104 can be implemented within the processor 102 or external to the processor 102 in which case those can be communicatively coupled to the processor 102 via various means as is known in the art.

The transceiver 106 is operatively coupled with the processor 102, and transmits and/or receives a radio signal. The transceiver 106 includes a transmitter and a receiver. The transceiver 106 may include baseband circuitry to process radio frequency signals. The transceiver 106 controls the one or more antennas 108 to transmit and/or receive a radio signal.

The power management module 110 manages power for the processor 102 and/or the transceiver 106. The battery 112 supplies power to the power management module 110.

The display 114 outputs results processed by the processor 102. The keypad 116 receives inputs to be used by the processor 102. The keypad 116 may be shown on the display 114.

The SIM card 118 is an　integrated circuit　that is intended to　securely store the　international mobile subscriber identity　(IMSI) number and its related　key, which are used to identify and authenticate subscribers on　mobile telephony　devices (such as　mobile phones　and　computers). It is also possible to store contact information on many SIM cards.

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

In particular, FIG. 5 illustrates an example of a radio interface user plane protocol stack between a UE and a BS and FIG. 6 illustrates an example of a radio interface control plane protocol stack between a UE and a BS. The control plane refers to a path through which control messages used to manage call by a UE and a network are transported. The user plane refers to a path through which data generated in an application layer, for example, voice data or Internet packet data are transported. Referring to FIG. 5, the user plane protocol stack may be divided into Layer 1 (i.e., a PHY layer) and Layer 2. Referring to FIG. 6, the control plane protocol stack may be divided into Layer 1 (i.e., a PHY layer), Layer 2, Layer 3 (e.g., an RRC layer), and a non-access stratum (NAS) layer. Layer 1, Layer 2 and Layer 3 are referred to as an access stratum (AS).

In the 3GPP LTE system, the Layer 2 is split into the following sublayers: MAC, RLC, and PDCP. In the 3GPP NR system, the Layer 2 is split into the following sublayers: MAC, RLC, PDCP and SDAP. The PHY layer offers to the MAC sublayer transport channels, the MAC sublayer offers to the RLC sublayer logical channels, the RLC sublayer offers to the PDCP sublayer RLC channels, the PDCP sublayer offers to the SDAP sublayer radio bearers. The SDAP sublayer offers to 5G core network quality of service (QoS) flows.

In the 3GPP NR system, the main services and functions of the MAC sublayer include: mapping between logical channels and transport channels; multiplexing/de-multiplexing of MAC SDUs belonging to one or different logical channels into/from transport blocks (TB) delivered to/from the physical layer on transport channels; scheduling information reporting; error correction through hybrid automatic repeat request (HARQ) (one HARQ entity per cell in case of carrier aggregation (CA)); priority handling between UEs by means of dynamic scheduling; priority handling between logical channels of one UE by means of logical channel prioritization; padding. A single MAC entity may support multiple numerologies, transmission timings and cells. Mapping restrictions in logical channel prioritization control which numerology(ies), cell(s), and transmission timing(s) a logical channel can use.

Different kinds of data transfer services are offered by MAC. To accommodate different kinds of data transfer services, multiple types of logical channels are defined, i.e., each supporting transfer of a particular type of information. Each logical channel type is defined by what type of information is transferred. Logical channels are classified into two groups: control channels and traffic channels. Control channels are used for the transfer of control plane information only, and traffic channels are used for the transfer of user plane information only. Broadcast control channel (BCCH) is a downlink logical channel for broadcasting system control information, paging control channel (PCCH) is a downlink logical channel that transfers paging information, system information change notifications and indications of ongoing public warning service (PWS) broadcasts, common control channel (CCCH) is a logical channel for transmitting control information between UEs and network and used for UEs having no RRC connection with the network, and dedicated control channel (DCCH) is a point-to-point bi-directional logical channel that transmits dedicated control information between a UE and the network and used by UEs having an RRC connection. Dedicated traffic channel (DTCH) is a point-to-point logical channel, dedicated to one UE, for the transfer of user information. A DTCH can exist in both uplink and downlink. In downlink, the following connections between logical channels and transport channels exist: BCCH can be mapped to broadcast channel (BCH); BCCH can be mapped to downlink shared channel (DL-SCH); PCCH can be mapped to paging channel (PCH); CCCH can be mapped to DL-SCH; DCCH can be mapped to DL-SCH; and DTCH can be mapped to DL-SCH. In uplink, the following connections between logical channels and transport channels exist: CCCH can be mapped to uplink shared channel (UL-SCH); DCCH can be mapped to UL-SCH; and DTCH can be mapped to UL-SCH.

The RLC sublayer supports three transmission modes: transparent mode (TM), unacknowledged mode (UM), and acknowledged node (AM). The RLC configuration is per logical channel with no dependency on numerologies and/or transmission durations. In the 3GPP NR system, the main services and functions of the RLC sublayer depend on the transmission mode and include: transfer of upper layer PDUs; sequence numbering independent of the one in PDCP (UM and AM); error correction through ARQ (AM only); segmentation (AM and UM) and re-segmentation (AM only) of RLC SDUs; reassembly of SDU (AM and UM); duplicate detection (AM only); RLC SDU discard (AM and UM); RLC re-establishment; protocol error detection (AM only).

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

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

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

Referring to FIG. 7, a gNB may include a gNB-CU (hereinafter, gNB-CU may be simply referred to as CU) and at least one gNB-DU (hereinafter, gNB-DU may be simply referred to as DU).

The gNB-CU is a logical node hosting RRC, SDAP and PDCP protocols of the gNB or an RRC and PDCP protocols of the en-gNB. The gNB-CU controls the operation of the at least one gNB-DU.

The gNB-DU is a logical node hosting RLC, MAC, and physical layers of the gNB or the en-gNB. The operation of the gNB-DU is partly controlled by the gNB-CU. One gNB-DU supports one or multiple cells. One cell is supported by only one gNB-DU.

The gNB-CU and gNB-DU are connected via an F1 interface. The gNB-CU terminates the F1 interface connected to the gNB-DU. The gNB-DU terminates the F1 interface connected to the gNB-CU. One gNB-DU is connected to only one gNB-CU. However, the gNB-DU may be connected to multiple gNB-CUs by appropriate implementation. The F1 interface is a logical interface. For NG-RAN, the NG and Xn-C interfaces for a gNB consisting of a gNB-CU and gNB-DUs, terminate in the gNB-CU. For E-UTRAN-NR dual connectivity (EN-DC), the S1-U and X2-C interfaces for a gNB consisting of a gNB-CU and gNB-DUs, terminate in the gNB-CU. The gNB-CU and connected gNB-DUs are only visible to other gNBs and the 5GC as a gNB.

Functions of the F1 interface includes F1 control (F1-C) functions as follows.

(1) F1 interface management function

The error indication function is used by the gNB-DU or gNB-CU to indicate to the gNB-CU or gNB-DU that an error has occurred.

The reset function is used to initialize the peer entity after node setup and after a failure event occurred. This procedure can be used by both the gNB-DU and the gNB-CU.

The F1 setup function allows to exchange application level data needed for the gNB-DU and gNB-CU to interoperate correctly on the F1 interface. The F1 setup is initiated by the gNB-DU.

The gNB-CU configuration update and gNB-DU configuration update functions allow to update application level configuration data needed between gNB-CU and gNB-DU to interoperate correctly over the F1 interface, and may activate or deactivate cells.

The F1 setup and gNB-DU configuration update functions allow to inform the single network slice selection assistance information (S-NSSAI) supported by the gNB-DU.

The F1 resource coordination function is used to transfer information about frequency resource sharing between gNB-CU and gNB-DU.

(2) System Information management function

Scheduling of system broadcast information is carried out in the gNB-DU. The gNB-DU is responsible for transmitting the system information according to the scheduling parameters available.

The gNB-DU is responsible for the encoding of NR master information block (MIB). In case broadcast of system information block type-1 (SIB1) and other SI messages is needed, the gNB-DU is responsible for the encoding of SIB1 and the gNB-CU is responsible for the encoding of other SI messages.

(3) F1 UE context management function

The F1 UE context management function supports the establishment and modification of the necessary overall UE context.

The establishment of the F1 UE context is initiated by the gNB-CU and accepted or rejected by the gNB-DU based on admission control criteria (e.g., resource not available).

The modification of the F1 UE context can be initiated by either gNB-CU or gNB-DU. The receiving node can accept or reject the modification. The F1 UE context management function also supports the release of the context previously established in the gNB-DU. The release of the context is triggered by the gNB-CU either directly or following a request received from the gNB-DU. The gNB-CU request the gNB-DU to release the UE Context when the UE enters RRC_IDLE or RRC_INACTIVE.

This function can be also used to manage DRBs and SRBs, i.e., establishing, modifying and releasing DRB and SRB resources. The establishment and modification of DRB resources are triggered by the gNB-CU and accepted/rejected by the gNB-DU based on resource reservation information and QoS information to be provided to the gNB-DU. For each DRB to be setup or modified, the S-NSSAI may be provided by gNB-CU to the gNB-DU in the UE context setup procedure and the UE context modification procedure.

The mapping between QoS flows and radio bearers is performed by gNB-CU and the granularity of bearer related management over F1 is radio bearer level. For NG-RAN, the gNB-CU provides an aggregated DRB QoS profile and QoS flow profile to the gNB-DU, and the gNB-DU either accepts the request or rejects it with appropriate cause value. To support packet duplication for intra-gNB-DU carrier aggregation (CA), one data radio bearer should be configured with two GPRS tunneling protocol (GTP)-U tunnels between gNB-CU and a gNB-DU.

With this function, gNB-CU requests the gNB-DU to setup or change of the special cell (SpCell) for the UE, and the gNB-DU either accepts or rejects the request with appropriate cause value.

With this function, the gNB-CU requests the setup of the secondary cell(s) (SCell(s)) at the gNB-DU side, and the gNB-DU accepts all, some or none of the SCell(s) and replies to the gNB-CU. The gNB-CU requests the removal of the SCell(s) for the UE.

(4) RRC message transfer function

This function allows to transfer RRC messages between gNB-CU and gNB-DU. RRC messages are transferred over F1-C. The gNB-CU is responsible for the encoding of the dedicated RRC message with assistance information provided by gNB-DU.

(5) Paging function

The gNB-DU is responsible for transmitting the paging information according to the scheduling parameters provided.

The gNB-CU provides paging information to enable the gNB-DU to calculate the exact paging occasion (PO) and paging frame (PF). The gNB-CU determines the paging assignment (PA). The gNB-DU consolidates all the paging records for a particular PO, PF and PA, and encodes the final RRC message and broadcasts the paging message on the respective PO, PF in the PA.

(6) Warning messages information transfer function

This function allows to cooperate with the warning message transmission procedures over NG interface. The gNB-CU is responsible for encoding the warning related SI message and sending it together with other warning related information for the gNB-DU to broadcast over the radio interface.

A transport network layer (TNL) is based on Internet protocol (IP) transport, comprising a stream control transmission protocol (SCTP) layer on top of the IP layer. An application layer signaling protocol is referred to as an F1 application protocol (E1AP).

Hereinafter, technical features related to UE Information are described. Sections of 3GPP TS 38.331 v18.0.0 may be referred.

FIG. 9 shows an example of UE information procedure.

The UE information procedure is used by the network to request the UE to report information.

The network initiates the procedure by sending the UEInformationRequest message. The network should initiate this procedure only after successful security activation.

Reception of the UEInformationRequest message

Upon receiving the UEInformationRequest message, the UE shall, only after successful security activation:

1> if the idleModeMeasurementReq is included in the UEInformationRequest and the UE has stored VarMeasIdleReport that contains measurement information concerning cells other than the PCell:

2> set the measResultIdleEUTRA in the UEInformationResponse message to the value of measReportIdleEUTRA in the VarMeasIdleReport , if available;

2> set the measResultIdleNR in the UEInformationResponse message to the value of measReportIdleNR in the VarMeasIdleReport, if available;

2> discard the VarMeasIdleReport upon successful delivery of the UEInformationResponse message confirmed by lower layers;

1> if the logMeasReportReq is present and if the RPLMN is included in plmn - IdentityList stored in VarLogMeasReport, or if the current registered SNPN is included in snpn - ConfigIDList stored in VarLogMeasReport:

2> if VarLogMeasReport includes one or more logged measurement entries, set the contents of the logMeasReport in the UEInformationResponse message as follows:

3> include the absoluteTimeStamp and set it to the value of absoluteTimeInfo in the VarLogMeasReport;

3> include the traceReference and set it to the value of traceReference in the VarLogMeasReport;

3> include the traceRecordingSessionRef and set it to the value of traceRecordingSessionRef in the VarLogMeasReport ;

3> include the tce -Id and set it to the value of tce -Id in the VarLogMeasReport;

3> include the logMeasInfoList and set it to include one or more entries from the VarLogMeasReport starting from the entries logged first, and for each entry of the logMeasInfoList that is included, include all information stored in the corresponding logMeasInfoList entry in VarLogMeasReport;

3> if the VarLogMeasReport includes one or more additional logged measurement entries that are not included in the logMeasInfoList within the UEInformationResponse message:

4> include the logMeasAvailable;

4> if bt - LocationInfo is included in locationInfo of one or more of the additional logged measurement entries in VarLogMeasReport that are not included in the logMeasInfoList within the UEInformationResponse message:

5> include the logMeasAvailableBT;

4> if wlan - LocationInfo is included in locationInfo of one or more of the additional logged measurement entries in VarLogMeasReport that are not included in the logMeasInfoList within the UEInformationResponse message:

5> include the logMeasAvailableWLAN;

1> if ra- ReportReq is set to true and the UE has random access related information available in VarRA -Report and if the RPLMN is included in plmn-IdentityList stored in VarRA -Report; or

1> if ra- ReportReq is set to true and the UE has random access related information available in VarRA -Report and if the registered SNPN is included in snpn - IdentityList stored in VarRA -Report:

2> set the ra- ReportList in the UEInformationResponse message to the value of ra- ReportList in VarRA -Report;

2> discard the ra- ReportList from VarRA -Report upon successful delivery of the UEInformationResponse message confirmed by lower layers;

1> if rlf - ReportReq is set to true:

2> if the UE has radio link failure information or handover failure information available in VarRLF -Report and if the RPLMN is included in plmn -IdentityList stored in VarRLF -Report; or

2> if the UE has radio link failure information or handover failure information available in VarRLF -Report and if the current registered SNPN is included in snpn - IdentityList stored in VarRLF -Report:

3> set timeSinceFailure in VarRLF -Report to the time that elapsed since the last radio link failure or handover failure in NR;

3> set the rlf -Report in the UEInformationResponse message to the value of rlf -Report in VarRLF -Report;

3> discard the rlf -Report from VarRLF -Report upon successful delivery of the UEInformationResponse message confirmed by lower layers;

2> else if the UE is capable of cross-RAT RLF reporting and has radio link failure information or handover failure information available in VarRLF-Report and if the RPLMN is included in plmn - IdentityList stored in VarRLF-Report:

3> set timeSinceFailure in VarRLF -Report to the time that elapsed since the last radio link failure or handover failure in EUTRA;

3> set failedPCellId-EUTRA in the rlf -Report in the UEInformationResponse message to indicate the PCell in which RLF was detected or the source PCell of the failed handover in the VarRLF -Report;

3> set the measResult - RLF -Report- EUTRA in the rlf -Report in the UEInformationResponse message to the value of rlf -Report in VarRLF -Report;

1> if connEstFailReportReq is set to true and the UE has connection establishment failure or connection resume failure information in VarConnEstFailReport or VarConnEstFailReportList and if the RPLMN is equal to plmn-Identity stored in VarConnEstFailReport or in at least one of the entries of VarConnEstFailReportList:

1> if connEstFailReportReq is set to true and if the UE has connection establishment failure information or connection resume failure information available in VarConnEstFailReport or VarConnEstFailReportList and if the registered SNPN identity is equal to snpn -identity stored in VarConnEstFailReport or any entry of VarConnEstFailReportList:

2> set timeSinceFailure in VarConnEstFailReport to the time that elapsed since the last connection establishment failure or connection resume failure in NR;

2> set the connEstFailReport in the UEInformationResponse message to the value of connEstFailReport in VarConnEstFailReport;

2> if the UE supports multiple CEF report:

3> for each connEstFailReport in the connEstFailReportList in VarConnEstFailReportList:

4> set timeSinceFailure to the time that elapsed since the associated connection establishment failure or connection resume failure in NR;

2> for each connEstFailReport in the connEstFailReportList in the UEInformationResponse message, set the value to the value of connEstFailReport in VarConnEstFailReport in VarConnEstFailReportList;

2> discard the connEstFailReport from VarConnEstFailReport and VarConnEstFailReportList upon successful delivery of the UEInformationResponse message confirmed by lower layers;

1> if the mobilityHistoryReportReq is set to true:

2> include the mobilityHistoryReport and set it to include visitedCellInfoList from VarMobilityHistoryReport;

2> include in the mobilityHistoryReport an entry for the current PCell, possibly after removing the oldest entry if required, and set its fields as follows:

3> set visitedCellId to the global cell identity or the physical cell identity and carrier frequency of the current PCell:

3> set field timeSpent to the time spent in the current PCell;

3> if the UE supports PSCell mobility history information and if visitedPSCellInfoList is present in VarMobilityHistoryReport:

4> for the newest entry of the PCell in the mobilityHistoryReport, include visitedPSCellInfoList from VarMobilityHistoryReport;

4> if the UE is configured with a PSCell:

5> for the newest entry of the PCell in the mobilityHistoryReport, include the current PSCell information in the visitedPSCellInfoListReport , possibly after removing the oldest PSCell entry of a PCell in the mobilityHistoryReport, if required, and set its fields as follows:

6> set visitedCellId to the global cell identity or the physical cell identity and carrier frequency of the current PSCell:

6> set field timeSpent to the time spent in the current PSCell while being connected to the current PCell;

4> else:

5> for the newest entry of the PCell in the mobilityHistoryReport, include a new entry in the visitedPSCellInfoListReport , possibly after removing the oldest PSCell entry of a PCell in the mobilityHistoryReport, if required, and set its fields as follows:

6> set field timeSpent to the time spent without PSCell in the current PCell since last PSCell release since connected to the current PCell in RRC_CONNECTED;

3> else if the UE supports PSCell mobility history information:

4> if the UE is configured with a PSCell:

4> else:

6> set field timeSpent to the time spent without PSCell in the current PCell since connected to the current PCell in RRC_CONNECTED;

1> if the successHO - ReportReq is set to true and if the UE has successful handover related information available in VarSuccessHO -Report and if the RPLMN is included in the plmn - IdentityList stored in VarSuccessHO -Report; or

1> if the successHO - ReportReq is set to true and if the UE has successful handover related information available in VarSuccessHO -Report and if the current registered SNPN is included in snpn - IdentityList if stored in the VarSuccessHO -Report:

2> if the successHO -Report in the VarSuccessHO -Report concerns a DAPS handover and if a PDCP PDU has been received from the source cell of the concerned HO and a non-duplicated PDCP PDU has been received from the target cell of the concerned HO:

3> set upInterruptionTimeAtHO in VarSuccessHO -Report to include the time elapsed between the time of arrival of the last PDCP PDU received from the source cell of the concerned handover and the time of arrival of the first non-duplicate PDCP PDU received from the target cell of the concerned handover, as measured at the time of arrival of the first non-duplicate PDCP PDU received from the target cell;

2> if the successHO -Report in the VarSuccessHO -Report concerns a mobilityFromNRCommand:

3> set timeSinceSHR in VarSuccessHO -Report to the time that elapsed since the execution of the associated mobilityFromNRCommand;

2> set the successHO -Report in the UEInformationResponse message to the value of successHO -Report in the VarSuccessHO -Report, if available;

2> discard the VarSuccessHO -Report upon successful delivery of the UEInformationResponse message confirmed by lower layers;

1> if the successPSCell - ReportReq is set to true and if the UE has successful PSCell change or addition information available in VarSuccessPSCell-Report and if the RPLMN is included in plmn - IdentityList stored in VarSuccessPSCell -Report; or

1> if the successPSCell - ReportReq is set to true and if the UE has successful PSCell change or addition information available in VarSuccessPSCell-Report and if the current registered SNPN is included in snpn-IdentityList if stored in the VarSuccessPSCell -Report:

2> set the successPSCell -Report in the UEInformationResponse message to the value of successPSCell -Report in the VarSuccessPSCell -Report;

2> discard the VarSuccessPSCell -Report upon successful delivery of the UEInformationResponse message confirmed by lower layers;

1> if the coarseLocationRequest is set to true:

2> include coarseLocationInfo , if available;

1> if the flightPathInfoReq is included in the UEInformationRequest and the UE has flight path information available, set the flightPathInfoReport in the UEInformationResponse message as follows:

2> include the list of up to maxWayPointNumber waypoints along the flight path;

2> if the includeTimeStamp is set to true, for each included waypoint:

3> if available, set the field timestamp to the time when UE intends to arrive at the waypoint;

1> if the logMeasReport is included in the UEInformationResponse:

2> submit the UEInformationResponse message to lower layers for transmission via SRB2;

2> discard the logged measurement entries included in the logMeasInfoList from VarLogMeasReport upon successful delivery of the UEInformationResponse message confirmed by lower layers;

1> else:

2> submit the UEInformationResponse message to lower layers for transmission via SRB1.

Actions for the Random Access report determination

Upon successfully performing random-access procedure initialized with 4-step or 2-step RA type, or upon failed or successfully completed on-demand system information acquisition procedure in RRC_IDLE or RRC_INACTIVE state, or upon failed or successfully completed RA-SDT operation, the UE shall:

1> if the RPLMN or the PLMN selected by upper layers from the PLMN(s) included in the plmn - IdentityList in SIB1 is not included in plmn -IdentityList stored in a non-empty VarRA -Report; or

1> if the registered SNPN or the SNPN selected by upper layers from the list of SNPN(s) included in the NPN - IdentityInfoList in SIB1is not included in plmn - IdentityList stored in a non-empty VarRA -Report:

2> clear the information included in VarRA -Report;

1> if the UE is not in SNPN access mode and if the number of RA-Report entries stored in the ra- ReportList in VarRA -Report is less than maxRAReport:

2> if the number of PLMN entries in plmn - IdentityList stored in VarRA-Report is less than maxPLMN; or

2> if the number of PLMN entries in plmn - IdentityList stored in VarRA-Report is equal to maxPLMN and the list of EPLMNs is subset of or equal to the plmn - IdentityList stored in VarRA -Report:

3> append the following contents associated to the successfully completed random-access procedure or the failed or successfully completed on-demand system information acquisition procedure as a new entry in the VarRA -Report:

4> if the list of EPLMNs has been stored by the UE:

5> set the plmn - IdentityList to include the list of EPLMNs stored by the UE (i.e. includes the RPLMN) without exceeding the limit of maxPLMN;

4> else:

5> set the plmn -Identity, in plmn - IdentityList, to the PLMN selected by upper layers from the PLMN(s) included in the plmn - IdentityInfoList in SIB1;

4> set the cellId to the global cell identity and the tracking area code, if available, otherwise to the physical cell identity and carrier frequency of the cell in which the corresponding random-access preamble was transmitted;

4> if the UE supports spCell ID indication:

5> if the corresponding random-access procedure was performed on an SCell of MCG:

6> set the spCellId to the global cell identity of the PCell;

5> if the corresponding random-access procedure was performed on an SCell of SCG:

6> set the spCellId to the global cell identity of the PSCell, if available, otherwise, set the spCellId to the global cell identity of the PCell;

5> if the corresponding random-access procedure was performed on PSCell:

6> if the cellId is not set to the global cell identity of the PSCell, set the spCellId to the global cell identity of the PCell;

4> set the raPurpose to include the purpose of triggering the random-access procedure;

4> set the ra- InformationCommon.

1> if the UE is in SNPN access mode and if the number of RA-Report entries stored in the ra- ReportList in VarRA -Report is less than maxRAReport:

2> if the number of SNPN identity entries in snpn - IdentityList stored in VarRA -Report is less than maxNPN; or

2> if the number of SNPN identity entries in snpn - IdentityList stored in VarRA -Report is equal to maxNPN and the list of equivalent SNPN(s) is subset of or equal to the snpn - IdentityList stored in VarRA -Report:

4> if the list of equivalent SNPN(s) has been stored by the UE:

5> set the snpn - IdentityList to include the list of equivalent SNPN(s) stored by the UE (i.e. includes the registered SNPN) without exceeding the limit of maxNPN;

4> else:

5> set the snpn -Identity, in snpn - IdentityList, to the SNPN identity selected by upper layers from the SNPN identities included in the NPN -IdentityInfoList in SIB1;

4> if the UE supports spCell ID indication:

6> set the spCellId to the global cell identity of the PCell;

5> if the corresponding random-access procedure was performed on PSCell:

4> set the ra- InformationCommon.

The UE may discard the random access report information, i.e. release the UE variable VarRA -Report, 48 hours after the last successful random access procedure or the failed or successfully completed on-demand system information acquisition procedure or the failed or successfully completed RA-SDT procedure related information is added to the VarRA -Report.

RA information determination

The UE shall, for the last successfully completed or last failed random-access procedure, set the content in ra- InformationCommon as follows:

1> set the absoluteFrequencyPointA to indicate the absolute frequency of the reference resource block associated to the random-access resources used in the random-access procedure;

1> set the locationAndBandwidth and subcarrierSpacing associated to the UL BWP of the random-access resources used in the random-access procedure;

1> if contention based random-access resources are used in the random-access procedure:

2> set the msgA _ RO - FrequencyStart and msgA - RO -FDM and msgA -SubcarrierSpacing associated to the 2 step random- access resources if used in the random-access procedure;

2> if msgA - SubcarrierSpacing associated to the 2 step random-access resources used in the random-access procedure is available:

3> set the msgA - SubcarrierSpacing associated to the 2 step random-access resources used in the random-access procedure;

2> else if only 2 step random-access resources are available in the UL BWP used in the random-access procedure:

3> set the msgA - SCS -From- prach - ConfigurationIndex to the subcarrier spacing as derived from the msgA - PRACH - ConfigurationIndex used in the 2-step random-access procedure;

2> else:

3> set the msg1 - SubcarrierSpacing associated to the 4 step random-access resources used in the random-access procedure;

2> set the msg1 - FrequencyStart associated to the 4 step random-access resources if used in the random-access procedure, and if its value is different from the value of msgA - RO - FrequencyStart if it is included in the ra-InformationCommon;

2> set the msg1 -FDM associated to the 4 step random-access resources if used in the random-access procedure, and if its value is different from the value of msgA - RO - FDMCFRA if it is included in the ra- InformationCommon ;

2> if msg1 - SubcarrierSpacing associated to the 4 step random-access resources used in the random-access procedure is available, and if its value is different from the value of msgA - SubcarrierSpacing if it is included in the ra- InformationCommon:

2> else:

3> set the msg1 - SCS -From- prach - ConfigurationIndex to the subcarrier spacing as derived from the prach - ConfigurationIndex used in the 4-step random-access procedure, and if its value is different from the value of msgA-SCS-From-prach-ConfigurationIndex if it is included in the ra-InformationCommon;

1> if contention free random-access resources are used in the random-access procedure:

2> set the msg1 - FrequencyStartCFRA and msg1 - FDMCFRA associated to the 4 step random-access resources if used in the random-access procedure;

2> if msg1 - SubcarrierSpacing associated to the 4 step random-access resources used in the random-access procedure is available:

3> set the msg1 - SubcarrierSpacingCFRA associated to the 4 step random-access resources used in the random-access procedure;

2> else:

3> set the msg1 - SCS -From- prach - ConfigurationIndexCFRA to the subcarrier spacing as derived from the prach - ConfigurationIndex used in the 4 step random-access procedure;

2> set the msgA - RO - FrequencyStartCFRA and msgA - RO - FDMCFRA associated to the 2 step contention free random access resources if used in the random-access procedure;

2> set the msgA -MCS, the nrofPRBs - PerMsgA -PO, the msgA - PUSCH -TimeDomainAllocation, the frequencyStartMsgA - PUSCH, the nrofMsgA -PO-FDM associated to the 2 step random-access resources if used in the random-access procedure;

2> else:

1> if the random access procedure is initialized with RA_TYPE set to 2-stepRA:

2> set the dlPathlossRSRP to the measeured RSRP of the DL pathloss reference obtained at the time of RA_Type selection stage of the initialization of the RA procedure;

2> if the configuration for the random access msgA - TransMax was configured in RACH - ConfigDedicated for this random access procedure, and raPurpose is set to reconfigurationWithSync:

3> set msgA - TransMax to the value of msgA - TransMax in RACH -ConfigDedicated;

2> else if msgA - TransMax was configured in RACH -ConfigCommonTwoStepRA:

3> set msgA - TransMax to the value of msgA - TransMax in RACH -ConfigCommonTwoStepRA;

2> set the msgA - PUSCH - PayloadSize to the size of the overall payload available in the UE buffer at the time of initiating the 2 step RA procedure;

1> if the purpose of the random access procedure is to request on-demand system information (i.e., if the raPurpose is set to requestForOtherSI or msg3RequestForOtherSI):

2> set the intendedSIBs to indicate the SIB(s) the UE wanted to receive as a result of the SI request;

2> set the ssbsForSI -Acquisition to indicate the SSB(s) used to receive the SI message;

2> if the on-demand system information acquisition was successful:

3> set the onDemandSISuccess to true;

1> if one or more of the features including RedCap and/or Slicing and/or SDT and/or MSG3 repetition are applicable for this random-access procedure:

2> set the triggeredFeatureCombination to indicate all the features triggering this random-access procedure as below:

3> if this random-access procedure is triggered by RedCap, includes redCap;

3> if this random-access procedure is triggered by SDT, includes smallData;

3> if this random-access procedure is triggered by Msg3 repetition, includes msg3 -Repetitions;

3> if this random-access procedure is triggered by slicing, set nsag to the NSAG ID applied in the random-access procedure and set the triggered-S-NSSAI-List to include all the S- NSSAI (s) associated to the slices triggering the access attempt in the random-access procedure;

2> if the value of used feature or combination of features is different from the triggeredFeatureCombination:

3> set the usedFeatureCombination to indicate one or more features of FeatureCombination associated to the random-access resource used in the random-access procedure as below:

4> if RedCap is part of the used FeatureCombination, include redCap;

4> if SDT is part of the used FeatureCombination, include smallData;

4> if Msg3 repetition is part of the used FeatureCombination, include msg3 -Repetitions;

4> if NSAG(s) is part of the used FeatureCombination, set NSAG -List to include the NSAG -ID(s) configured for the used FeatureCombination;

1> if the random-access procedure is initiated for SDT and the SDT transmission was failed:

3> include the sdt -Failed;

1> set the parameters associated to the successive random-access attempts associated to the selected beam in the perRAInfoList as follows:

2> if the random-access resource used is associated to a SS/PBCH block, set the associated random-access parameters for the successive random-access attempts associated to the same SS/PBCH block for one or more random-access attempts as follows:

3> set the ssb -Index to include the SS/PBCH block index associated to the used random-access resource;

3> set the numberOfPreamblesSentOnSSB to indicate the number of successive random-access attempts associated to the SS/PBCH block;

3> if all preamble transmissions for the successive random-access attempts associated to this SS/PBCH block were blocked by LBT:

4> include allPreamblesBlocked;

3> else:

4> if LBT failure indication was received from lower layers for the last random-access preamble transmission attempt in the SS/PBCH block associated to the ssb -Index, before changing the SS/PBCH block for random access preamble transmission:

5> include lbt -Detected;

3> for each random-access attempt performed on the random-access resource, except the random-access attempts for which LBT failure indication was received from lower layers, include the following parameters in the chronological order of the random-access attempt:

4> if the random-access attempt is performed on the contention based random-access resource and if raPurpose is not equal to 'requestForOtherSI', include contentionDetected as follows:

5> if contention resolution was not successful for the transmitted preamble:

6> set the contentionDetected to true;

5> else:

6> set the contentionDetected to false;

4> if the random access attempt is a 2-step random access attempt:

5> if fallback from 2-step random access to 4-step random access occurred during the random access attempt:

6> set fallbackToFourStepRA to true;

4> if the random-access attempt is performed on the contention based random-access resource; or

4> if the random-access attempt is performed on the contention free random-access resource and if the random-access procedure was initiated due to the PDCCH ordering:

5> if the random access attempt is a 4-step random access attempt and the SS/PBCH block RSRP of the SS/PBCH block corresponding to the random-access resource used in the random-access attempt is above rsrp - ThresholdSSB; or

5> if the random access attempt is a 2-step random access attempt and the SS/PBCH block RSRP of the SS/PBCH block corresponding to the random-access resource used in the random-access attempt is above msgA - RSRP -ThresholdSSB:

6> set the dlRSRPAboveThreshold to true;

5> else:

6> set the dlRSRPAboveThreshold to false;

2> else if the random-access resource used is associated to a CSI-RS, set the associated random-access parameters for the successive random-access attempts associated to the same CSI-RS for one or more random-access attempts as follows:

3> set the csi - RS -Index to include the CSI-RS index associated to the used random-access resource;

3> set the numberOfPreamblesSentOnCSI - RS to indicate the number of successive random-access attempts associated to the CSI-RS;

3> if all preamble transmissions for the successive random-access attempts associated to this CSI-RS were blocked by LBT:

4> include allPreamblesBlocked;

3> else:

4> if LBT failure indication was received from lower layers for the last random-access preamble transmission attempt in the CSI-RS associated to the csi - RS -Index, before changing the CSI-RS for random access preamble transmission:

5> include lbt -Detected;

1> if at least one LBT failure indication has been received from lower layers during the random-access procedure:

2> set the numberOfLBTFailures to indicate the total number of random-access attempts for which LBT failure indications have been received from lower layers in the random-access procedure.

The UE shall, for all the BWPs in which consistent LBT failures are triggered and not cancelled at the moment of successful RA completion or for all the BWPs in which consistent LBT failures are detected prior the RLF/HOF, set the below parameters in attemptedBWP - InfoList in the chronological order of BWP selection:

1> set the locationAndBandwidth and subcarrierSpacing associated to the UL BWP.

- If allPreamblesBlocked is included, it is left to UE implementation how to set the numberOfPreamblesSentOnSSB -r16, numberOfPreamblesSentOnCSI - RS -r16 and the perRAAttemptInfoList -r16.

Actions for the successful handover report determination

The UE shall for the PCell:

1> if the procedure is triggered due to successful completion of reconfiguration with sync, and if the ratio between the value of the elapsed time of the timer T304 and the configured value of the timer T304, included in the last applied RRCReconfiguration message including the reconfigurationWithSync, is greater than thresholdPercentageT304 if included in the successHO - Config received before executing the last reconfiguration with sync; or

1> if the procedure is triggered due to successful completion of reconfiguration with sync, and if the ratio between the value of the elapsed time of the timer T310 and the configured value of the timer T310, configured while the UE was connected to the source PCell before executing the last reconfiguration with sync, is greater than thresholdPercentageT310 included in the successHO - Config if configured by the source PCell before executing the last reconfiguration with sync; or

1> if the procedure is triggered due to successful completion of reconfiguration with sync, and if the T312 associated to the measurement identity of the target cell was running at the time of initiating the execution of the reconfiguration with sync procedure and if the ratio between the value of the elapsed time of the timer T312 and the configured value of the timer T312, configured while the UE was connected to the source PCell before executing the last reconfiguration with sync, is greater than thresholdPercentageT312 included in the successHO - Config if configured by the source PCell before executing the last reconfiguration with sync; or

1> if the procedure is triggered due to successful completion of reconfiguration with sync, and if sourceDAPS - FailureReporting is included in the successHO - Config before executing the last reconfiguration with sync and is set to true and if the last executed handover was a DAPS handover and if an RLF occurred at the source PCell during the DAPS handover while T304 was running; or:

1> if the procedure is triggered due to successful completion of Mobility from NR to E-UTRA, and if the ratio between the value of the elapsed time of the timer T310 and the configured value of the timer T310, configured while the UE was connected to the source PCell before executing the last Mobility from NR to E-UTRA, is greater than thresholdPercentageT310 included in the successHO - Config if configured by the source PCell before executing the last Mobility from NR to E-UTRA; or

1> if the procedure is triggered due to successful completion of Mobility from NR to E-UTRA, and if the T312 associated to the measurement identity of the target cell was running at the time of initiating the execution of the Mobility from NR to E-UTRA and if the ratio between the value of the elapsed time of the timer T312 and the configured value of the timer T312, configured while the UE was connected to the source PCell before executing the last Mobility from NR to E-UTRA, is greater than thresholdPercentageT312 included in the successHO - Config if configured by the source PCell before executing the last Mobility from NR to E-UTRA:

2> store the successful handover information in VarSuccessHO -Report and determine the content in VarSuccessHO -Report as follows:

3> clear the information included in VarSuccessHO -Report, if any;

3> if the UE is not in SNPN access mode, set the plmn - IdentityList to include the list of EPLMNs stored by the UE (i.e., includes the RPLMN);

3> else if the UE is in SNPN access mode, set the snpn - IdentityList to include the list of equivalent SNPNs stored by the UE (i.e., includes the registered SNPN), if available;

3> set the c- RNTI to the C-RNTI assigned by the target PCell of the handover;

3> if the procedure is triggered due to successful completion of reconfiguration with sync, for the source PCell in which the last RRCReconfiguration message including reconfigurationWithSync was applied; or

3> if the procedure is triggered due to successful completion of Mobility from NR to E-UTRA, for the source PCell in which the last MobilityFromNRCommand concerning an inter-RAT handover from NR to E-UTRA was applied:

4> set the sourcePCellID in sourceCellInfo to the global cell identity and tracking area code, if available, of the source PCell;

4> set the sourceCellMeas in sourceCellInfo to include the cell level RSRP, RSRQ and the available SINR, of the source PCell based on the available SSB and CSI-RS measurements collected up to the moment the UE sends RRCReconfigurationComplete message if the procedure is triggered due to successful completion of reconfiguration with sync, or up to the moment the UE sends the EUTRA RRCConnectionReconfigurationComplete message if the procedure is triggered due to successful completion of Mobility from NR to E-UTRA;

4> set the rsIndexResults in sourceCellMeas to include all the available SSB and CSI-RS measurement quantities of the source PCell collected up to the moment the UE sends RRCReconfigurationComplete message if the procedure is triggered due to successful completion of reconfiguration with sync, or up to the moment the UE sends the EUTRA RRCConnectionReconfigurationComplete message if the procedure is triggered due to successful completion of Mobility from NR to E-UTRA;

4> if the last executed handover was a DAPS handover and if an RLF occurred at the source PCell during the DAPS handover while T304 was running:

5> set the rlf - InSourceDAPS in sourceCellInfo to true;

3> if the procedure is triggered due to successful completion of reconfiguration with sync, for the target PCell indicated in the last applied RRCReconfiguration message including reconfigurationWithSync:

4> set the targetPCellID in targetCellInfo to the global cell identity and tracking area code, if available, of the target PCell;

4> set the targetCellMeas in targetCellInfo to include the cell level RSRP, RSRQ and the available SINR, of the target PCell based on the available SSB and CSI-RS measurements collected up to the moment the UE sends RRCReconfigurationComplete message;

4> set the rsIndexResults in targetCellMeas to include all the available SSB and CSI-RS measurement quantities of the target PCell collected up to the moment the UE sends RRCReconfigurationComplete message;

4> if the last applied RRCReconfiguration message including reconfigurationWithSync was included in the stored condRRCReconfig:

5> set the timeSinceCHO - Reconfig to the time elapsed between the initiation of the execution of conditional reconfiguration for the target PCell and the reception of the last conditionalReconfiguration including the condRRCReconfig of the target PCell in the source PCell;

3> if the procedure is triggered due to successful completion of Mobility from NR to E-UTRA, for the target PCell indicated in the last applied MobilityFromNRCommand concerning an inter-RAT handover from NR to E-UTRA:

4> set the targetPCellId in eutraTargetCellInfo to the global cell identity and tracking area code, if available, of the target PCell;

4> set the targetCellMeas in eutraTargetCellInfo to include the cell level RSRP, RSRQ and the available SINR, of the target PCell based on the available measurements collected up to the moment the UE sends RRCConnectionReconfigurationComplete message;

3> if the procedure is triggered due to successful completion of reconfiguration with sync and if the ratio between the value of the elapsed time of the timer T304 and the configured value of the T304 timer, included in the last applied RRCReconfiguration message including the reconfigurationWithSync, is greater than thresholdPercentageT304 if included in the successHO - Config received before executing the last reconfiguration with sync:

4> set t304-cause in shr -Cause to true;

4> set the ra- InformationCommon to include the random-access related information associated to the random access procedure in the target PCell;

3> if the ratio between the value of the elapsed time of the timer T310 and the configured value of the T310 timer, configured while the UE was connected to the source PCell before executing the last reconfiguration with sync or the last Mobility from NR to E-UTRA, is greater than thresholdPercentageT310 included in the successHO - Config if configured by the source PCell before executing the last reconfiguration with sync or Mobility from NR to E-UTRA:

4> set t310-cause in shr -Cause to true;

3> if the T312 associated to the measurement identity of the target cell was running at the time of initiating the execution of the reconfiguration with sync procedure or Mobility from NR to E-UTRA, and if the ratio between the value of the elapsed time of the timer T312 and the configured value of the T312 timer, configured while the UE was connected to the source PCell before executing the last reconfiguration with sync or Mobility from NR to E-UTRA, is greater than thresholdPercentageT312 included in the successHO - Config if configured by the source PCell before executing the last reconfiguration with sync, or Mobility from NR to E-UTRA:

4> set t312-cause in shr -Cause to true;

3> if the procedure is triggered due to successful completion of reconfiguration with sync and if sourceDAPS - FailureReporting included in the successHO-Config if configured by the source PCell before executing the last reconfiguration with sync is set to true, and if the last executed handover was a DAPS handover and if an RLF occurred at the source PCell during the DAPS handover while T304 was running:

4> set sourceDAPS -Failure in shr -Cause to true;

3> if the procedure is triggered due to successful completion of reconfiguration with sync, for each of the measObjectNR, configured by the source PCell, in which the last RRCReconfiguration message including reconfigurationWithSync was applied;or:

3> if the procedure is triggered due to successful completion of Mobility from NR to E-UTRA, for each of the measObjectNR, configured by the source PCell, in which the last MobilityFromNRCommand concerning an inter-RAT handover from NR to E-UTRA was applied:

4> if measRSSI - ReportConfig is configured for the frequency of the source PCell:

5> if the procedure is triggered due to successful completion of reconfiguration with sync:

6> set the measResultServCell - RSSI to the linear average of the available RSSI sample value(s) provided by lower layers for the frequency of the source PCell up to the moment the UE sends the RRCReconfigurationComplete message

5> else if the procedure is triggered due to successful completion of Mobility from NR to E-UTRA:

6> set the measResultServCell - RSSI to the linear average of the available RSSI sample value(s) provided by lower layers for the frequency of the source PCell up to the moment the UE sends the EUTRA RRCConnectionReconfigurationComplete message;

4> for each of the configured measObjectNR if measRSSI - ReportConfig is configured for the configured frequency:

6> set the measResultNeighFreq - RSSI in the measResultNeighFreqList -RSSI to the linear average of the available RSSI sample value(s) provided by lower layers for the associated neighbouring frequency up to the moment the UE sends the RRCReconfigurationComplete message;

6> set the measResultNeighFreq - RSSI in the measResultNeighFreqList -RSSI to the linear average of the available RSSI sample value(s) provided by lower layers for the associated neighbouring frequency up to the moment the UE sends the EUTRA RRCConnectionReconfigurationComplete message;

4> if measurements are available for the measObjectNR:

5> if the SS/PBCH block-based measurement quantities are available:

6> set the measResultListNR in measResultNeighCells to include all the available measurement quantities of the best measured cells, other than the source PCell or target PCell, ordered such that the cell with highest SS/PBCH block RSRP is listed first if SS/PBCH block RSRP measurement results are available, otherwise the cell with highest SS/PBCH block RSRQ is listed first if SS/PBCH block RSRQ measurement results are available, otherwise the cell with highest SS/PBCH block SINR is listed first, based on the available SS/PBCH block based measurements collected up to the moment the UE sends the RRCReconfigurationComplete message if the procedure is triggered due to successful completion of reconfiguration with sync, or up to the moment the UE sends the EUTRA RRCConnectionReconfigurationComplete message if the procedure is triggered due to successful completion of Mobility from NR to E-UTRA;

6> for each neighbour cell included, include the optional fields that are available;

- For the neighboring cells set included in measResultListNR in measResultNeighCells ordered based on the SS/PBCH block measurement quantities, the UE includes also the CSI-RS based measurement quantities, if available.

5> if the CSI-RS measurement quantities are available:

6> set the measResultListNR in measResultNeighCells to include all the available measurement quantities of the best measured cells, other than the source PCell and target PCell, ordered such that the cell with highest CSI-RS RSRP is listed first if CSI-RS RSRP measurement results are available, otherwise the cell with highest CSI-RS RSRQ is listed first if CSI-RS RSRQ measurement results are available, otherwise the cell with highest CSI-RS SINR is listed first, based on the available CSI-RS based measurements collected up to the moment the UE sends the RRCReconfigurationComplete message if the procedure is triggered due to successful completion of reconfiguration with sync, or up to the moment the UE sends the EUTRA RRCConnectionReconfigurationComplete message if the procedure is triggered due to successful completion of Mobility from NR to E-UTRA;

- For the neighboring cells set ordered based on the CSI-RS measurement quantities, the UE includes measurements only for the cells not yet included in measResultListNR in measResultNeighCells to avoid overriding SS/PBCH block-based ordered measurements.

3> if the procedure is triggered due to successful completion of reconfiguration with sync, for each of the measObjectEUTRA, configured by the source PCell in which the last RRCReconfiguration message including reconfigurationWithSync was applied; or:

3> if the procedure is triggered due to successful completion of Mobility from NR to E-UTRA, for each of the measObjectEUTRA, configured by the source PCell in which the last MobilityFromNRCommand concerning an inter-RAT handover from NR to E-UTRA was applied:

4> if measurements are available for the measObjectEUTRA:

5> set the measResultListEUTRA in measResultNeighCells to include the best measured cells ordered such that the cell with highest RSRP is listed first if RSRP measurement results are available, otherwise the cell with highest RSRQ is listed first, based on measurements collected up to the moment the UE sends the RRCReconfigurationComplete message if the procedure is triggered due to successful completion of reconfiguration with sync, or up to the moment the UE sends the EUTRA RRCConnectionReconfigurationComplete message if the procedure is triggered due to successful completion of Mobility from NR to E-UTRA;

5> for each neighbour cell included, include the optional fields that are available;

3> for each of the neighbour cells included in measResultNeighCells:

4> if the cell was a candidate target cell included in the condRRCReconfig within the conditionalReconfiguration configured by the source PCell, in which the last RRCReconfiguration message including reconfigurationWithSync was applied:

5> set the choCandidate to true in measResultNR;

3> if available, set the locationInfo;

1> release successHO - Config configured by the source PCell and thresholdPercentageT304 if configured by the target PCell.

The UE may discard the successful handover information, i.e., release the UE variable VarSuccessHO -Report, 48 hours after the last successful handover information is added to the VarSuccessHO -Report.

Hereinafter, technical features related to L1/L2-Triggered Mobility are described. Sections of 3GPP TS 38.300 v18.0.0 may be referred.

LTM is a procedure in which a gNB receives L1 measurement report(s) from a UE, and on their basis the gNB changes UE serving cell by a cell switch command signalled via a MAC CE. The cell switch command indicates an LTM candidate configuration that the gNB previously prepared and provided to the UE through RRC signalling. Then the UE switches to the target configuration according to the cell switch command. The LTM procedure can be used to reduce the mobility latency as described in Annex G.

When configured by the network, it is possible to activate TCI states of one or multiple cells that are different from the current serving cell. For instance, the TCI states of the LTM candidate cells can be activated in advance before any of those cells become the serving cell. This allows the UE to be DL synchronized with those cells, thereby facilitating a faster cell switch to one of those cells when cell switch is triggered.

When configured by the network, it is possible to initiate UL TA acquisition (called early TA) procedure of one or multiple cells that are different from the current serving cells. If the cell has the same N_TA as the current serving cells or N_TA=0, early TA acquisition procedure is not required. The network may request the UE to perform early TA acquisition of a candidate cell before a cell switch. The early TA acquisition procedure is triggered by PDCCH order or realized through UE-based TA measurement as configured by RRC. In the former case, the gNB to which the candidate cell belongs calculates the TA value and sends it to the gNB to which the serving cell belongs. The serving cell sends the TA value in the LTM cell switch command MAC CE when triggering LTM cell switch. In the latter case, the UE performs TA measurement for the candidate cells after being configured by RRC but the exact time the UE performs TA measurement is up to UE implementation. The UE applies the TA value measured by itself and performs RACH-less LTM upon receiving the cell switch command. The network may also send a TA value in the LTM cell switch command MAC CE without early TA acquisition.

Depending on the availability of a valid TA value, the UE performs either a RACH-less LTM or RACH-based LTM cell switch. If the TA value is provided in the cell switch command, the UE applies the TA value as instructed by the network. In the case where UE-based TA measurement is configured, but no TA value is provided in the cell switch command, the UE applies the TA value by itself if available. Meanwhile, the UE performs RACH-less LTM cell switch upon receiving the cell switch command. If no valid TA value is available, the UE performs RACH-based LTM cell switch.

Regardless of whether the UE is configured for UE-based TA measurement for a certain candidate cell, it will still follow the PDCCH order, which includes requesting a random access procedure towards the candidate cells. This also applies to the candidate cells for which the UE is capable of deriving TA values by itself. Additionally, regardless of whether the UE has already performed a random access procedure towards the candidate cells, it will still follow the UE-based measurement configuration if configured by the network.

For RACH-less LTM, the UE accesses the target cell using either a configured grant or a dynamic grant. The configured grant is provided in the LTM candidate configuration, and the UE selects the configured grant occasion associated with the beam indicated in the cell switch command. Upon initiation of LTM cell switch to the target cell, the UE starts to monitor PDCCH on the target cell for dynamic scheduling. Before RACH-less LTM procedure completion, the UE shall not trigger random access procedure if it does not have a valid PUCCH resource for triggered SRs.

The following principles apply to LTM:

- Security key is maintained upon an LTM cell switch;

- Subsequent LTM is supported.

LTM supports both intra-gNB-DU and intra-gNB-CU inter-gNB-DU mobility. LTM supports both intra-frequency and inter-frequency mobility, including mobility to inter-frequency cell that is not a current serving cell. LTM is supported only for licensed spectrum. The following scenarios are supported:

- PCell change in non-CA scenario and non-DC scenario;

- PCell and SCell(s) change in CA scenario;

- Dual connectivity scenario, PCell and MCG SCell(s) change and intra-SN PSCell and SCG SCell(s) change without MN involvement. LTM for simultaneous PCell and PSCell change is not supported.

While the UE has stored LTM candidate configurations the UE can also execute any L3 handover command sent by the network.

C-Plane Handling

Cell switch command is conveyed in a MAC CE, which contains the necessary information to perform the LTM cell switch.

The overall procedure for LTM is shown in FIG. 10 below. Subsequent LTM is done by repeating the early synchronization, LTM cell switch execution, and LTM cell switch completion steps without releasing other LTM candidate configurations after each LTM cell switch completion. The general procedure over the air interface is applicable to SCG LTM.

FIG. 10 shows an example of Signalling procedure for LTM.

The procedure for LTM is as follows:

In step S1001, the UE sends a MeasurementReport message to the gNB. The gNB decides to configure LTM and initiates LTM preparation.

In step S1002, the gNB transmits an RRCReconfiguration message to the UE including the LTM candidate configurations.

In step S1003, the UE stores the LTM candidate configurations and transmits an RRCReconfigurationComplete message to the gNB.

In step S1004a, the UE performs DL synchronization with the candidate cell(s) before receiving the cell switch command.

In step S1004b, when UE-based TA measurement is configured, UE acquires the TA value(s) of the candidate cell(s) by measurement. UE performs early TA acquisition with the candidate cell(s) as requested by the network before receiving the cell switch command. This is done via CFRA triggered by a PDCCH order from the source cell, following which the UE sends preamble towards the indicated candidate cell. In order to minimize the data interruption of the source cell due to CFRA towards the candidate cell(s), the UE does not receive random access response from the network for the purpose of TA value acquisition and the TA value of the candidate cell is indicated in the cell switch command. The UE does not maintain the TA timer for the candidate cell and relies on network implementation to guarantee the TA validity.

In step S1005, the UE performs L1 measurements on the configured candidate cell(s) and transmits L1 measurement reports to the gNB. L1 measurement should be performed as long as RRC reconfiguration (step S1002) is applicable.

In step S1006, the gNB decides to execute cell switch to a target cell and transmits a MAC CE triggering cell switch by including the candidate configuration index of the target cell. The UE switches to the target cell and applies the configuration indicated by candidate configuration index.

In step S1007, the UE performs the random access procedure towards the target cell, if UE does not have valid TA of the target cell.

In step S1008, the UE completes the LTM cell switch procedure by sending RRCReconfigurationComplete message to target cell. If the UE has performed a RA procedure in step S1007 the UE considers that LTM cell switch execution is successfully completed when the random access procedure is successfully completed. For RACH-less LTM, the UE considers that LTM cell switch execution is successfully completed when the UE determines that the network has successfully received its first UL data.

The steps S1004-S1008 can be performed multiple times for subsequent LTM using the LTM candidate configuration(s) provided in step S1002.

The procedure over the air interface described in Figure x is applicable to both intra-gNB-DU LTM and inter-gNB-DU LTM.

U-Plane Handling

After receiving an LTM cell switch command MAC CE, the UE performs MAC reset. Whether the UE performs RLC re-establishment and PDCP data recovery during cell switch is explicitly controlled by the network through RRC signalling.

Hereinafter, technical features related to Data collection for SON (Self-Organising Networks)/MDT (Minimization of Drive Tests) in NR standalone and MR-DC (Multi-Radio Dual Connectivity) are described.

The objective of this work item is to specify data collection enhancement in NR standalone and MR-DC for SON/MDT purpose. The specific objectives of this work item are:

- Mobility Robustness Optimization (MRO) enhancement for R18 mobility mechanisms, including, Lower layer triggered mobility (LTM), CHO with candidate SCGs, subsequent CPAC [RAN3, RAN2]:

> Specification of the inter-node information exchange, including possible enhancements to interfaces [RAN3]

> Identify and specify necessary UE reporting to enhance the mobility parameter tuning　[RAN2]

- Support of SON/MDT enhancements for [RAN3, RAN2]:

> Intra-NTN mobility

> Network Slicing

- Support of the leftovers in Rel-18 SON/MDT [RAN3, RAN2]:

> RACH optimization for SDT

> MHI Enhancement for SCG Deactivation/Activation

> MRO for MR-DC SCG failure

If needed, co-operate with RAN1, SA2, SA5, CT4.

In particular, MRO support for lower layer triggered mobility (LTM) is discussed in NR.

This procedure is used for the case when the UE moves from one gNB-DU to another gNB-DU within the same gNB-CU during NR operation for LTM.

In step S1101, the UE sends a MeasurementReport message (L3 measurement result) to the source gNB-DU containing measurements of neighbouring cells. The source gNB-DU sends an UL RRC MESSAGE TRANSFER message conveying the received MeasurementReport message to the gNB-CU.

In step S1102, the gNB-CU determines to initiate LTM configuration.

In step S1103, the gNB-CU sends a UE CONTEXT SETUP REQUEST message to the candidate gNB-DU(s) for each candidate cell, containing one target candidate cell ID, the LTM configuration ID of the candidate cell, LTM configuration ID mapping list, and the CSI resource configuration. The gNB-CU may request PRACH resources from the candidate gNB-DU(s). The gNB-CU may request the candidate gNB-DU to provide the lower layer configuration for the purpose of generating the reference configuration or provide the lower layer reference configuration to the candidate gNB-DU.

In step S1104, if the candidate gNB-DU accepts the request of LTM configuration, it responds with a UE CONTEXT SETUP RESPONSE message including the generated lower layer RRC configurations for the accepted target candidate cell.

In step S1105, the gNB-CU sends a UE CONTEXT MODIFICATION REQUEST message to the source gNB-DU including the information related to early sync and the LTM configuration IDs for the accepted target candidate cell(s) in other gNB-DU(s). The gNB-CU may send the updated CSI resource configuration to the source gNB-DU.

In step S1106, the source gNB-DU responds with a UE CONTEXT MODIFICATION RESPONSE message which includes an updated lower layer configuration, e.g., containing the updated CSI report configuration of the source cell.

In step S1107, the gNB-CU may send a UE CONTEXT MODIFICATION REQUEST message to the candidate gNB-DU(s) containing the information for subsequent LTM or for updating the configurations of candidate cells. The gNB-CU may also provide the lower layer part of the reference configuration to the candidate gNB-DU(s).

In step S1108, the candidate gNB-DU responds with a UE CONTEXT MODIFICATION RESPONSE message including the updated lower layer configuration (e.g., the updated CSI report configuration).

For example, Step 1107 may also be triggered after step S1119, or after step S1122 by implementation for subsequent LTM.

In step S1109, the gNB-CU sends a DL RRC MESSAGE TRANSFER message to the source gNB-DU, which includes the generated RRCReconfiguration message with the LTM configuration.

In step S1110, the source gNB-DU forwards the received RRCReconfiguration message to the UE.

In step S1111, the UE responds to the source gNB-DU with an RRCReconfigurationComplete message.

In step S1112, the source gNB-DU forwards the RRCReconfigurationComplete message to the gNB-CU via an UL RRC MESSAGE TRANSFER message.

In step S1113, early synchronization to the target candidate cell(s) may be performed.

In step S1114, the candidate gNB-DU sends the TA value, the associated CFRA resource information, the candidate cell ID and the source gNB-DU ID to the source gNB-DU in the DU-CU TA INFORMATION TRANSFER message to the gNB-CU.

In step S1115, the gNB-CU forwards the TA value, and the associated CFRA resource information to the source gNB-DU in the CU-DU TA INFORMATION TRANSFER message.

In step S1116, the UE sends the L1 measurement result to the source gNB-DU.

In step S1117, the source gNB-DU decides to execute LTM to a candidate target cell.

In step S1118, the source gNB-DU sends the Cell Switch command to the UE.

In step S1119, the source gNB-DU sends the DU-CU CELL SWITCH NOTIFICATION message to the gNB-CU to indicate the initiation of the Cell Switch command to the UE, for which the message includes the target cell ID and the TCI state ID.

In step S1120, the gNB-CU forwards the target cell ID and the TCI state ID to the target gNB-DU in the CU-DU CELL SWITCH NOTIFICATION message.

In step S1121, the target gNB-DU detects the UE access.

In step S1122, the target gNB-DU sends the ACCESS SUCCESS message to the gNB-CU with the target cell ID.

In step S1123, the UE sends an RRCReconfigurationComplete message to the target gNB-DU.

In step S1124, the target gNB-DU forwards the RRCReconfigurationComplete message to the gNB-CU via an UL RRC MESSAGE TRANSFER message.

In step S1125, the gNB-CU may send the UE CONTEXT RELEASE COMMAND message to the source gNB-DU to release the resources of prepared cells.

In step S1126, the source gNB-DU responds with a UE CONTEXT RELEASE COMPLETE message.

Meanwhile, in NR, based on the measurement report provided by the UE, the gNB-CU determines the Lower layer Triggered Mobility (LTM). The UE can be configured UE-based timing advance (TA) measurement for the candidate target cell by the gNB-CU. Based on the configuration related to the received UE-based TA measurement, the UE performs TA measurement to obtain a suitable TA.

Hereinafter, a method for lower layer triggered mobility in a wireless network system, according to some embodiments of the present disclosure, will be described with reference to the following drawings.

The following drawings are created to explain specific embodiments of the present disclosure. The names of the specific devices or the names of the specific signals/messages/fields shown 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 used in the following drawings. Herein, a wireless device may be referred to as a user equipment (UE).

In particular, FIG. 12 shows an example of a method performed by a wireless device.

In step S1201, the wireless device may receive, from a Central Unit (CU) of a Radio Access Network (RAN) node via a source Distributed Unit (DU) of the RAN node, a Lower layer Triggered Mobility (LTM) configuration.

For example, the LTM configuration may include LTM information related to a candidate target DU. For example, the LTM configuration may include information related to inter-DU LTM.

In step S1202, the wireless device may transmit, to the source DU, a measurement report.

For example, the measurement report may include a Layer 1 (L1) (for example, the PHY layer) measurement report.

In step S1203, the wireless device may receive, from the source DU, a cell switch command for an LTM to a candidate DU of the RAN node.

For example, the source DU may determine the cell switch for the wireless device based on the L1 measurement report from the wireless device. The source DU may transmit, to the candidate DU via the CU, a cell switch notification message informing that the cell switch command is provided to the wireless device.

In step S1204, the wireless device may perform a RACH-based LTM to the candidate DU.

For example, the wireless device may receive a TA measurements configuration. The wireless device may perform TA measurements based on the TA measurements configuration. The wireless device may determine that a suitable TA for the candidate DU of the RAN node is not calculated based on the TA measurements before receiving the cell switch command.

Since the wireless device does not have the suitable TA for the candidate DU, the wireless device may not perform the RACH-less LTM to the candidate DU. Therefore, the wireless device may perform the RACH-based LTM to the candidate DU.

In step S1205, the wireless device may transmit, to the CU via the candidate DU, a message including (i) information related to Timing advance (TA) measurements and/or (ii) information related to the RACH-based LTM.

For example, the information related to TA measurements may include a TA measurement Indication informing whether the wireless device acquires a TA value for the candidate DU based on the TA measurements.

For example, the information related to TA measurements may include information related to an acquired TA value.

For example, the information related to TA measurements may include information related to a TA measurements configuration provided by the CU.

For example, the information related to the RACH-based LTM informs that the wireless device performs the RACH-based LTM instead of a RACH-less LTM.

According to some embodiments of the present disclosure, the CU may modify the TA measurements configuration for the wireless device based on the information related to the TA measurements included in the message from the wireless device.

For example, the wireless device may receive, from the CU, an updated TA measurements configuration. In this case, the updated TA measurements configuration may be configured by the CU of the RAN node based on the information related to the TA measurements. In this case, the wireless device may perform the TA measurements based on the updated TA measurements configuration.

For example, the wireless device may receive, from the CU, a configuration informing not to perform the TA measurements. The CU may determine to not configure the UE-based TA measurements for the wireless device. In this case, the wireless device may perform the LTM to the other candidate target DU after acquiring the TA value for the other candidate target DU.

For example, the wireless device may receive, from the source DU, a cell switch command for an LTM to another candidate target DU with a TA value for the other candidate target DU. That is, the source DU may provide the TA value for the other candidate target DU within the cell switch command. In this case, the wireless device could perform the RACH-less LTM to the other candidate target DU based on the TA value.

According to some embodiments of the present disclosure, the wireless device may be in communication with at least one of a user equipment, a network, or an autonomous vehicle other than the wireless device.

Hereinafter, technical features related to MRO support for lower layer triggered mobility are described.

The candidate target cell may belong to a different gNB-DU than the gNB-DU to which the source cell belongs. The UE may be configured with UE-based TA measurement for the candidate target cell. Before obtaining a suitable TA for the candidate target cell, the UE may receive a Cell Switch Command to perform inter-gNB-DU LTM to the candidate target cell.

At this time, some problems may occur (for example, the UE does not establish a proper RRC connection to the target cell).

In order to prevent other UEs configured with UE-based TA measurement to perform inter-gNB-DU LTM in the future from experiencing the same or similar issues, a UE configured with UE-based TA measurement may provide (i) TA Measurement Indication, (ii) measured TA value, and/or (iii) configuration information provided by the gNB-CU to configure UE-based TA measurement to the UE, to the gNB-CU via the gNB-DU which has the RRC connection with the UE.

Here, the TA Measurement Indication may indicate whether the UE for which UE-based TA measurement is set has obtained a suitable TA for the candidate target cell before receiving the Cell Switch Command. The measured TA value may include the TA value for the candidate target cell calculated by the UE for which UE-based TA measurement is set.

The gNB-CU that receives this information can store the received information. Other UEs that perform inter-gNB-DU LTM and that have UE-based TA measurement configurations may report the information related to TA measurement a certain period of time or under certain conditions. The gNB-CU may store the received information.

The gNB-CU can modify the configuration related to the UE-based TA measurement for the candidate target cell provided to the UE based on the stored information. Alternatively, the gNB-CU may not configure the UE-based TA measurement to the UE for the candidate target cell (for other example, the gNB-CU may transmit a release command for the UE-based TA measurement configuration). Alternatively, the gNB-CU may provide the UE with the TA through the Cell Switch Command.

The method proposed in the present disclosure can also be applied to intra-gNB-DU LTM.

For example, the candidate target cell may belong to a different gNB-DU than the gNB-DU to which the source cell belongs. Before a UE configured with the UE-based TA measurement obtains a suitable TA for a candidate target cell, the UE may receive a Cell Switch Command to perform inter-gNB-DU LTM to that target cell.

In particular, FIG. 13a, FIG. 13b, and FIG. 13c provide a method to prevent problems that may occur at this time from reoccurring in other UEs that have UE-based TA measurement configuration and perform inter-gNB-DU LTM in the future.

In step S1301, the UE may send a Measurement Report message including measurements results for neighboring cells to the source gNB-DU. The source gNB-DU may send, to the gNB-CU, a UL RRC MESSAGE TRANSFER message including the received Measurement Report message.

In step S1302, the gNB-CU may decide to start LTM configuration.

In step S1303, the gNB-CU may send, to the candidate gNB-DU, a UE CONTEXT SETUP REQEUST message including the candidate target cell ID, the LTM configuration ID of the candidate cell, the LTM configuration ID mapping list, and the CSI resource configuration.

The gNB-CU may indicate the source gNB-DU ID via this message and request PRACH resources from the candidate gNB-DU.

A gNB-CU may use this message to request a candidate gNB-DU to provide a lower layer configuration for the purpose of creating a reference configuration.

In step S1304, if the candidate gNB-DU accepts the LTM configuration request, the candidate gNB-DU may send, to the gNB-CU, a UE CONTEXT SETUP RESPONSE message including the lower layer RRC configuration (for example, TCI state configuration, RACH configuration, and CSI report configuration) for the accepted target candidate cell.

In step S1305, the gNB-CU may send, to the source gNB-DU¸ a UE CONTEXT MODIFICATION REQUEST message including the lower layer RRC configuration of the candidate gNB-DU.

In step S1306, the source gNB-DU may send, to the gNB-CU, a UE CONTEXT MODIFICATION RESPONSE message including the updated lower layer configuration.

In step S1307, gNB-CU may transmit, to the source gNB-DU, a DL RRC MESSAGE TRANSFER message including an RRC Reconfiguration message with LTM configuration. The LTM configuration may include UE-based TA measurement related configurations for allowing the UE to directly calculate TA values.

In step S1308, the source gNB-DU may forward the received RRC Reconfiguration message to the UE.

In step S1309, the UE may send, to the source gNB-DU, an RRC Reconfiguration Complete message as response.

In step S1310, the source gNB-DU may forward the RRC Reconfiguration Complete message to the gNB-CU via the UL RRC MESSAGE TRANSFER message.

In step S1311, UE may send L1 measurement report to source gNB-DU.

In step S1312, the source gNB-DU may decide to perform LTM to the candidate target cell.

In step S1313, the source gNB-DU may send a Cell Switch Command to the UE.

In step S1314, in order to notify that the Cell Switch Command has been delivered to the UE, the source gNB-DU may send, to the gNB-CU, a DU-CU CELL SWITCH NOTIFICATION message including the target cell ID and TCI state ID.

In step S1315, the gNB-CU may forward target cell ID and TCI state ID to target gNB-DU using a CU-DU CELL SWITCH NOTIFICATION message.

In step S1316, if the UE receives a Cell Switch Command from the source gNB-DU, while the UE has not yet calculated a suitable TA value for the target cell, the UE may attempt a RACH-based LTM cell switch to the target cell since there is no suitable TA.

In this case, even though the gNB-CU intended for the UE to perform a RACH-less LTM cell switch using UE-based TA measurement for the target cell, but since the UE performed a RACH-based LTM cell switch, the interruption/latency may increase.

In step S1317, the target gNB-DU may detect the access of the UE.

In step S1318, the target gNB-DU may send, to the gNB-CU, an ACCESS SUCCESS message including the target cell ID.

In step S1319, the UE may send an RRC Reconfiguration Complete message to target gNB-DU.

In step S1320, the target gNB-DU may forward, to the gNB-CU, the RRC Reconfiguration Complete message via the UL RRC MESSAGE TRANSFER message.

In step S1321, the gNB-CU may send a DL RRC MESSAGE TRANSFER message including a UE Information Request message to the target gNB-DU.

For example, the target gNB-DU may be a gNB-DU serving the UE.

For example, it may be another gNB-DU serving the UE other than the target gNB-DU in the above embodiment, since the UE may perform subsequent LTM.

For example, after comparing the target cell information included in the DU-CU CELL SWITCH NOTIFICATION message sent by the source gNB-DU with the cell currently accessed by the UE, the gNB-CU may send a UE Information Request message to the target gNB-DU.

In step S1322, the target gNB-DU may forward the received UE Information Request message to the UE.

In step S1323, the UE sends a UE Information Response message to the target gNB-DU in response. This message may contain one or more of the following information.

- TA Measurement Indication: Indicating whether the UE has obtained a suitable TA value based on UE-based TA measurement. It may be in the form of a flag (1 bit).

- Measured TA value: The TA value calculated by the UE based on UE-based TA measurement. If there is no calculated TA value, it may have a value of 0 or may not have any value (no value).

- Configuration information provided by the gNB-CU to configure the UE with UE-based TA measurement.

The above information may be included in the UE Information Response message. Additionally, the above information may be included in at least one of the Radio Link Failure Report, RACH Report, Connection Establishment Failure Report, or Successful Handover Report.

In step S1324, the target gNB-DU may forward the UE Information Response message to the gNB-CU via the UL RRC MESSAGE TANSFER message.

After receiving this message, the gNB-CU may store the UE-based TA measurement related information included in the received UE Information Response message.

Other UEs that perform inter-gNB-DU LTM in the future and have UE-based TA measurement configuration may continue to report information related to UE-based TA measurement for a certain period of time or under certain conditions. In this case, the gNB-CU may modify the UE-based TA measurement related configuration considering the collected information. Otherwise, the gNB-CU may not configure the UE-based TA measurement. Otherwise, the gNB-CU may provide TA through the Cell Switch Command.

In particular, FIG. 14 illustrates a method for reducing a problem that may occur when a UE configured with UE-based TA measurement for a candidate target cell receives a Cell Switch Command to perform inter-gNB-DU LTM before obtaining a suitable TA. In addition, FIG. 14 shows an example of a method performed by a gNB-CU.

In step S1401, the gNB-CU may receive information related to TA measurements, via the target gNB-DU, from a UE.

For example, the gNB-CU may receive (i) a TA Measurement Indication, (ii) a measured TA value, and/or (iii) configuration information provided to the UE in order to configure UE-based TA measurement, via the target gNB-DU, from the UE for which UE-based TA measurement is configured.

In step S1402, the gNB-CU may modify the UE-based TA measurement related configuration based on the received information.

That is, the gNB-CU may store the information received from the UE. The gNB-CU may receive reports on the above information from other UEs that perform inter-gNB-DU LTM and have UE-based TA measurement configuration within a certain period or condition. Based on the reported information, the gNB-CU may modify the UE-based TA measurement related configuration for the candidate target cell which is provided to the UE. Alternatively, the gNB-CU may not configure the UE with the UE-based TA measurement for the candidate target cell. Alternatively, the gNB-CU may provide the TA through the Cell Switch Command.

For example, the TA Measurement Indication may indicate whether the UE configured with UE-based TA measurement for the candidate target cell has obtained a suitable TA for the candidate target cell before receiving the Cell Switch Command from the source gNB-DU.

For example, the measured TA value may mean the TA value calculated by the UE configured with UE-based TA measurement for the candidate target cell.

For example, the above information provided by the UE configured with UE-based TA measurement may be included in a UE Information Response message. Alternatively, the above information provided by the UE configured with UE-based TA measurement may be included in at least one of a Radio Link Failure Report, a RACH Report, a Connection Establishment Failure Report, or a Successful Handover Report.

Some of the detailed steps shown in the examples of FIG. 12, FIG. 13a, FIG. 13b, FIG. 13c, and FIG. 14 may not be essential steps and may be omitted. In addition to the steps shown in FIG. 12, FIG. 13a, FIG. 13b, FIG. 13c, and FIG. 14, other steps may be added, and the order of the steps may vary. Some of the above steps may have their own technical meaning.

Hereinafter, an apparatus for lower layer triggered mobility in a wireless network system, according to some embodiments of the present disclosure, will be described.

Herein, the wireless device may include a transceiver, a memory, and a processor operatively coupled to the transceiver and the memory. For example, the wireless device may be the first wireless device 100 or the second wireless device 200 of FIGS. 2 and 3, or the UE 100 of FIG. 4.

The processor may be adapted to receive, from a Central Unit (CU) of a Radio Access Network (RAN) node via a source Distributed Unit (DU) of the RAN node, a Lower layer Triggered Mobility (LTM) configuration. The processor may be adapted to transmit, to the source DU, a measurement report. The processor may be adapted to receive, from the source DU, a cell switch command for an LTM to a candidate DU of the RAN node. The processor may be adapted to perform a RACH-based LTM to the candidate DU. The processor may be adapted to transmit, to the CU via the candidate DU, a message including (i) information related to Timing advance (TA) measurements and/or (ii) information related to the RACH-based LTM.

For example, the measurement report may include a Layer 1 (L1) measurement report.

For example, the processor may be adapted to receive a TA measurements configuration. For example, the processor may be adapted to perform TA measurements based on the TA measurements configuration. For example, the processor may be adapted to determine that a suitable TA for the candidate DU of the RAN node is not calculated based on the TA measurements before receiving the cell switch command.

For example, the processor may be adapted to receive, from the CU, an updated TA measurements configuration. For example, the updated TA measurements configuration may be configured by the CU of the RAN node based on the information related to the TA measurements.

For example, the processor may be adapted to receive, from the CU, a configuration informing not to perform the TA measurements.

For example, the processor may be adapted to receive, from the CU, a cell switch command for an LTM to another candidate target DU with a TA value for the other candidate target DU.

For example, the information related to the RACH-based LTM may inform that the wireless device performs the RACH-based LTM instead of a RACH-less LTM.

For example, the wireless device may be in communication with at least one of a user equipment, a network, or an autonomous vehicle other than the wireless device.

Hereinafter, a processor for a wireless device for lower layer triggered mobility in a wireless network system, according to some embodiments of the present disclosure, will be described.

The processor may be configured to control the wireless device to receive, from a Central Unit (CU) of a Radio Access Network (RAN) node via a source Distributed Unit (DU) of the RAN node, a Lower layer Triggered Mobility (LTM) configuration. The processor may be configured to control the wireless device to transmit, to the source DU, a measurement report. The processor may be configured to control the wireless device to receive, from the source DU, a cell switch command for an LTM to a candidate DU of the RAN node. The processor may be configured to control the wireless device to perform a RACH-based LTM to the candidate DU. The processor may be configured to control the wireless device to transmit, to the CU via the candidate DU, a message including (i) information related to Timing advance (TA) measurements and/or (ii) information related to the RACH-based LTM.

For example, the processor may be configured to control the wireless device to receive a TA measurements configuration. For example, the processor may be configured to control the wireless device to perform TA measurements based on the TA measurements configuration. For example, the processor may be configured to control the wireless device to determine that a suitable TA for the candidate DU of the RAN node is not calculated based on the TA measurements before receiving the cell switch command.

For example, the processor may be configured to control the wireless device to receive, from the CU, an updated TA measurements configuration. For example, the updated TA measurements configuration may be configured by the CU of the RAN node based on the information related to the TA measurements.

For example, the processor may be configured to control the wireless device to receive, from the CU, a configuration informing not to perform the TA measurements.

For example, the processor may be configured to control the wireless device to receive, from the CU, a cell switch command for an LTM to another candidate target DU with a TA value for the other candidate target DU.

Hereinafter, a non-transitory computer-readable medium has stored thereon a plurality of instructions for lower layer triggered mobility in a wireless network system, according to some embodiments of the present disclosure, will be described.

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

Some example of storage medium is coupled to the processor such that the processor can read information from the storage medium. In the alternative, the storage medium may be integral to the processor. The processor and the storage medium may reside in an ASIC. For another example, the processor and the storage medium may reside as discrete components.

The computer-readable medium may include a tangible and non-transitory computer-readable storage medium.

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

In addition, the method described herein may be realized at least in part by a computer-readable communication medium that carries or communicates code in the form of instructions or data structures and that can be accessed, read, and/or executed by a computer.

According to some embodiment of the present disclosure, a non-transitory computer-readable medium has stored thereon a plurality of instructions. The stored a plurality of instructions may be executed by a processor of a wireless device.

The stored a plurality of instructions may cause the wireless device to receive, from a Central Unit (CU) of a Radio Access Network (RAN) node via a source Distributed Unit (DU) of the RAN node, a Lower layer Triggered Mobility (LTM) configuration. The stored a plurality of instructions may cause the wireless device to transmit, to the source DU, a measurement report. The stored a plurality of instructions may cause the wireless device to receive, from the source DU, a cell switch command for an LTM to a candidate DU of the RAN node. The stored a plurality of instructions may cause the wireless device to perform a RACH-based LTM to the candidate DU. The stored plurality of instructions may cause the wireless device to transmit, to the CU via the candidate DU, a message including (i) information related to Timing advance (TA) measurements and/or (ii) information related to the RACH-based LTM.

For example, the stored a plurality of instructions may cause the wireless device to receive a TA measurements configuration. For example, the stored a plurality of instructions may cause the wireless device to perform TA measurements based on the TA measurements configuration. For example, the stored a plurality of instructions may cause the wireless device to determine that a suitable TA for the candidate DU of the RAN node is not calculated based on the TA measurements before receiving the cell switch command.

For example, the stored a plurality of instructions may cause the wireless device to receive, from the CU, an updated TA measurements configuration. For example, the updated TA measurements configuration may be configured by the CU of the RAN node based on the information related to the TA measurements.

For example, the stored a plurality of instructions may cause the wireless device to receive, from the CU, a configuration informing not to perform the TA measurements.

For example, the stored a plurality of instructions may cause the wireless device to receive, from the CU, a cell switch command for an LTM to another candidate target DU with a TA value for the other candidate target DU.

Hereinafter, a RAN node for lower layer triggered mobility in a wireless network system, according to some embodiments of the present disclosure, will be described.

The RAN node may be the gNB in FIG. 7. The RAN node may include a Central Unit (CU) and at least one Distributed Unit (DU). For example, the RAN node may include a source DU and/or a candidate target DU.

The CU of the RAN node may comprise a memory and at least one processor. The at least one processor may be operatively coupled to the memory.

The at least one processor may be adapted to transmit, to a wireless device via a source Distributed Unit (DU) of the RAN node, a Lower layer Triggered Mobility (LTM) configuration. The wireless device may transmit, to the source DU, the measurement report. The wireless device may receive, from the source DU, a cell switch command for an LTM to a candidate DU of the RAN node. The wireless device may perform a RACH-based LTM to the candidate DU. The at least one processor may be adapted to receive, from the wireless device via the candidate DU, a message including (i) information related to Timing advance (TA) measurements and/or (ii) information related to the RACH-based LTM.

Hereinafter, a method performed by a RAN node for lower layer triggered mobility in a wireless network system, according to some embodiments of the present disclosure, will be described.

The CU of the RAN node may transmit, to a wireless device via a source Distributed Unit (DU) of the RAN node, a Lower layer Triggered Mobility (LTM) configuration. The wireless device may transmit, to the source DU, the measurement report. The wireless device may receive, from the source DU, a cell switch command for an LTM to a candidate DU of the RAN node. The wireless device may perform a RACH-based LTM to the candidate DU. The CU of the RAN node may receive, from the wireless device via the candidate DU, a message including (i) information related to Timing advance (TA) measurements and/or (ii) information related to the RACH-based LTM.

The present disclosure can have various advantageous effects.

Claims in the present disclosure can be combined in a various way. For instance, technical features in method claims of the present disclosure can be combined to be implemented or performed in an apparatus, and technical features in apparatus claims can be combined to be implemented or performed in a method. Further, technical features in method claim(s) and apparatus claim(s) can be combined to be implemented or performed in an apparatus. Further, technical features in method claim(s) and apparatus claim(s) can be combined to be implemented or performed in a method. Other implementations are within the scope of the following claims.

Claims

A method, comprising:

receiving, by a wireless device from a Central Unit (CU) of a Radio Access Network (RAN) node via a source Distributed Unit (DU) of the RAN node, a Lower layer Triggered Mobility (LTM) configuration;

transmitting, by the wireless device to the source DU, a measurement report;

receiving, by the wireless device from the source DU, a cell switch command for an LTM to a candidate DU of the RAN node;

performing, by the wireless device, a Random Access Channel (RACH)-based LTM to the candidate DU; and

transmitting, by the wireless device to the CU via the candidate DU, a message including (i) information related to Timing advance (TA) measurements and/or (ii) information related to the RACH-based LTM.
The method of claim 1,

wherein the information related to TA measurements includes a TA measurement Indication informing whether the wireless device acquires a TA value for the candidate DU based on the TA measurements.
The method of claim 1,

wherein the information related to TA measurements includes information related to an acquired TA value.
The method of claim 1,

wherein the information related to TA measurements includes information related to a TA measurements configuration provided by the CU.
The method of claim 1,

wherein the measurement report includes a Layer 1 (L1) measurement report.
The method of claim 1, wherein the method further comprising:

receiving, by the wireless device, a TA measurements configuration.
The method of claim 6, wherein the method further comprising:

performing, by the wireless device, TA measurements based on the TA measurements configuration.
The method of claim 7, wherein the method further comprising:

determining, by the wireless device, that a suitable TA for the candidate DU of the RAN node is not calculated based on the TA measurements before receiving the cell switch command.
The method of claim 1, wherein the method further comprising:

receiving, by the wireless device from the CU, an updated TA measurements configuration.
The method of claim 9,

wherein the updated TA measurements configuration is configured by the CU of the RAN node based on the information related to the TA measurements.
The method of claim 1, wherein the method further comprising:

receiving, by the wireless device from the CU, a configuration informing not to perform the TA measurements.
The method of claim 1, wherein the method further comprising:

receiving, by the wireless device from the source DU, a cell switch command for an LTM to another candidate target DU with a TA value for the other candidate target DU.
The method of claim 1,

wherein the information related to the RACH-based LTM informs that the wireless device performs the RACH-based LTM instead of a RACH-less LTM.
The method of claim 1,

wherein the wireless device is in communication with at least one of a user equipment, a network, or an autonomous vehicle other than the wireless device.
A wireless device, comprising:

at least one transceiver;

at least one processor; and

at least one memory operably connectable to the at least one processor and storing instructions that, based on being executed by the at least one processor, perform operations comprising:

receiving, from a Central Unit (CU) of a Radio Access Network (RAN) node via a source Distributed Unit (DU) of the RAN node, a Lower layer Triggered Mobility (LTM) configuration;

transmitting, to the source DU, a measurement report;

receiving, from the source DU, a cell switch command for an LTM to a candidate DU of the RAN node;

performing a RACH-based LTM to the candidate DU; and

transmitting, to the CU via the candidate DU, a message including (i) information related to Timing advance (TA) measurements and/or (ii) information related to the RACH-based LTM.
The wireless device of claim 15,

wherein the information related to TA measurements includes a TA measurement Indication informing whether the wireless device acquires a TA value for the candidate DU based on the TA measurements.
The wireless device of claim 15,

wherein the information related to TA measurements includes information related to an acquired TA value.
The wireless device of claim 15,

wherein the information related to TA measurements includes information related to a TA measurements configuration provided by the CU.
The wireless device of claim 15,

wherein the measurement report includes a Layer 1 (L1) measurement report.
The wireless device of claim 15, wherein the operations further comprising:

receiving a TA measurements configuration.
The wireless device of claim 20, wherein the operations further comprising:

performing TA measurements based on the TA measurements configuration.
The wireless device of claim 21, wherein the operations further comprising:

determining that a suitable TA for the candidate DU of the RAN node is not calculated based on the TA measurements before receiving the cell switch command.
The wireless device of claim 15, wherein the operations further comprising:

receiving, from the CU, an updated TA measurements configuration.
The wireless device of claim 23,

wherein the updated TA measurements configuration is configured by the CU of the RAN node based on the information related to the TA measurements.
The wireless device of claim 15, wherein the operations further comprising:

receiving, from the CU, a configuration informing not to perform the TA measurements.
The wireless device of claim 15, wherein the operations further comprising:

receiving, from the CU, a cell switch command for an LTM to another candidate target DU with a TA value for the other candidate target DU.
The wireless device of claim 15,

wherein the information related to the RACH-based LTM informs that the wireless device performs the RACH-based LTM instead of a RACH-less LTM.
The wireless device of claim 15,

wherein the wireless device is in communication with at least one of a user equipment, a network, or an autonomous vehicle other than the wireless device.
A processor for a wireless device in a wireless communication system, wherein the processor is adapted to control the wireless device to perform operations comprising:

receiving, from a Central Unit (CU) of a Radio Access Network (RAN) node via a source Distributed Unit (DU) of the RAN node, a Lower layer Triggered Mobility (LTM) configuration;

transmitting, to the source DU, a measurement report;

receiving, from the source DU, a cell switch command for an LTM to a candidate DU of the RAN node;

performing a RACH-based LTM to the candidate DU; and

transmitting, to the CU via the candidate DU, a message including (i) information related to Timing advance (TA) measurements and/or (ii) information related to the RACH-based LTM.
A non-transitory computer-readable medium having stored thereon a plurality of instructions, which, when executed by a processor of a wireless device, cause the wireless device to perform operations, the operations comprising,

receiving, from a Central Unit (CU) of a Radio Access Network (RAN) node via a source Distributed Unit (DU) of the RAN node, a Lower layer Triggered Mobility (LTM) configuration;

transmitting, to the source DU, a measurement report;

receiving, from the source DU, a cell switch command for an LTM to a candidate DU of the RAN node;

performing a RACH-based LTM to the candidate DU; and

transmitting, to the CU via the candidate DU, a message including (i) information related to Timing advance (TA) measurements and/or (ii) information related to the RACH-based LTM.
A method performed by a Central Unit (CU) of a Radio Access Network (RAN) node in a wireless communication system, the method comprising,

transmitting, to a wireless device via a source Distributed Unit (DU) of the RAN node, a Lower layer Triggered Mobility (LTM) configuration,

wherein the wireless device transmits, to the source DU, the measurement report,

wherein the wireless device receives, from the source DU, a cell switch command for an LTM to a candidate DU of the RAN node, and

wherein the wireless device performs a RACH-based LTM to the candidate DU; and

receiving, from the wireless device via the candidate DU, a message including (i) information related to Timing advance (TA) measurements and/or (ii) information related to the RACH-based LTM.
A Central Unit (CU) of a Radio Access Network (RAN) node, comprising:

a memory; and

at least one processor operatively coupled to the memory, and adapted to:

transmit, to a wireless device via a source Distributed Unit (DU) of the RAN node, a Lower layer Triggered Mobility (LTM) configuration,

wherein the wireless device transmits, to the source DU, the measurement report,

wherein the wireless device receives, from the source DU, a cell switch command for an LTM to a candidate DU of the RAN node, and

wherein the wireless device performs a RACH-based LTM to the candidate DU; and

receive, from the wireless device via the candidate DU, a message including (i) information related to Timing advance (TA) measurements and/or (ii) information related to the RACH-based LTM.