Methods and apparatus for RRC idle and RRC inactive NTN measurement reporting

Abstract

The disclosure relates to a 5G or 6G communication system for supporting higher data transmission rates and satisfying various service requirements. The disclosure provides a method performed by a terminal in a wireless communication system. The method may include: receiving, from a base station, non-terrestrial network (NTN) measurement configuration information for performing NTN measurement; performing a measurement on an NTN cell, the terminal being in a radio resource control (RRC) idle state or RRC inactive state; entering an RRC connected state; and transmitting, to the base station, a result of the measurement.

Description

METHODS AND APPARATUS FOR RRC IDLE AND RRC INACTIVE NTN MEASUREMENT REPORTING

[0001] The disclosure relates to operations of network node and a terminal in a wireless communication system, and more particularly relates to measurement reporting in RRC idle and RRC inactive states in non-terrestrial networks.

[0002] 5thgeneration (5G) mobile communication technology defines a wide frequency band to enable fast transmission speeds and new services, and can be implemented not only in the sub-6 gigahertz (GHz) frequency band such as 3.5GHz, but also in the ultra-high frequency band referred to as millimeter wave (mmWave) bands such as 28GHz and 39GHz (above 6GHz) bands. In 6th generation (6G) mobile communication technology, referred to as beyond 5G, it is expected that it will be paramount to secure new frequency resources such as the sub-6GHz band, ultra-high frequency bands, and upper mid band (7-24GHz) to handle the rapidly increased data traffic due to the spread of artificial intelligence (AI) technology and the increase in streaming services, to improve user perceived performance, and to efficiently utilize all available frequency resources as needed. To this end, reallocation, reuse, or sharing of existing frequency bands from 2nd generation (2G) to 5G for 6G can be considered.

[0003] Since the introduction of 5G, the communications market has been increasingly interested in improving system operation efficiency, sustainability, and user experience. Accordingly, in addition to improving traditional communications performance such as data transmission speed and delay time, the introduction of new innovative technologies such as AI, reducing operating costs, improving energy efficiency, expanding service coverage, and introducing new services are becoming increasingly important.

[0004] Since the early stages of 5G mobile communication technology, a goal has been to support services and satisfy performance requirements for enhanced mobile broadband (eMBB), ultra-reliable low-latency communications (URLLC), and massive machine-type communications (mMTC), including beamforming and massive multiple-input multiple-output (MIMO) to mitigate path loss of radio waves in ultra-high frequency bands and increase the range of radio transmission, support for various numerologies (such as operation of multiple subcarrier intervals) and dynamic operation of slot formats for efficient use of ultra-high frequency resources, initial access technology to support multi-beam transmission and wideband, definition and operation of band-width part (BWP), new channel coding methods such as low density parity check (LDPC) codes for large-capacity data transmission and polar codes for reliable transmission of control information, layer 2 (L2) pre-processing, and networks that provide dedicated networks specialized for specific services. Standardization of slicing (network slicing) etc. has been progressing.

[0005] Furthermore, discussions have been held on improving and enhancing the initial 5G mobile communication technology in consideration of the services that 5G mobile communication technology was intended to support, including vehicle-to-everything (V2X) to help autonomous vehicles make decisions based on their own location and status information transmitted by the vehicle and to increase user convenience, new radio unlicensed (NR-U) for system operation that meets various regulatory requirements in unlicensed bands, NR terminal low power consumption technology (i.e., UE power saving), non-terrestrial network (NTN), which is direct terminal-satellite communication to secure coverage in areas where communication with terrestrial networks is impossible, positioning, NR support up to 71GHz, support of reduced capability NR devices for lower cost and complexity compared to general terminals, user equipment (UE) power saving enhancement for improved power management in preparation for the use of various terminal types, and sidelink. Standardization of the physical layer has been performed for technologies such as sidelink enhancement, duplex enhancements which study a new form of duplexing called subband non-overlapping full duplex (SBFD), network energy saving which secures the idle period in which the base station operates in maximum power saving mode to the maximum extent and reduces power consumption, and network controlled repeaters which have improved performance compared to existing repeaters by having the function of receiving and processing side control information from the network.

[0006] In addition, standardization of the wireless interface architecture / protocol layer for technologies such as the industrial Internet of things (IIoT) for supporting new services through linkage and convergence with other industries, integrated access and backhaul (IAB) that provides nodes for expanding network service areas by integrating wireless backhaul links and access links, mobility enhancement technology including conditional handover (CHO) and dual active protocol stack (DAPS) handover, 2-step random access channel (RACH) for NR that simplifies random access procedures, multicast and broadcast, standardization of support for multi universal subscriber identity module (USIM) devices that provide services to users using information of two or more subscriber identity modules (SIMs), sidelink relay that provides relay-related functions to support connections between terminals in long distances and between terminals and networks, small data transfer (SDT) which transmits small data or signaling in an inactive state without transitioning to a connected state, mobility enhancements including layer 1 (L1) / L2 triggered mobility (LTM) / subsequent conditional PSCell addition / change (SCPAC) / and conditional handover (CHO) with candidate SCGs, extended reality (XR) enhancement to support XR services in NR systems, etc. has also been performed, and standardization of system architecture / services such as 5G baseline architecture (e.g., service-based architecture, service-based interface) for grafting network functions virtualization (NFV) and software-defined networking (SDN) technologies, mobile edge computing (MEC) that provides services based on the location of the terminal, non-public networks (NPN) that can be used only by some permitted terminals for non-public purposes, disaster roaming that supports the use of communication services through other carriers' networks in the event of a communication disaster, proximity-based service via 5GS, and unmanned Standardization has also been made in the system architecture / service areas, including support of an unmanned aircraft system (UAS) to support remote identification, tracking, and authorization of uncrewed aerial vehicles (UAVs), structural enhancements to support XR and interactive media services, 5GS to support AI / machine learning (ML) services, and advanced mobile edge computing to provide edge computing services in roaming networks, etc. has also been performed.

[0007] Currently, standardization is in progress for technologies such as beam prediction using AI / ML technology, channel state information (CSI) prediction to improve positioning accuracy, ultra-low-power terminal technology using low-power wake-up receivers, technology for transmitting long term evolution (LTE) broadcasts to 5G networks, MIMO transmission technology using multiple base stations, and ultra-low-power terminals (ambient IoT) that transmit data by obtaining power from an external source without a battery. At the radio interface architecture / protocol layer, standardization is in progress for technologies such as LTM scenario support and conditional LTM support between central units (CUs), simultaneous support for the same XR service between multiple devices, NTN coverage enhancement and evolution, AI / ML-based mobility support, and terminal-to-terminal connection relay across multiple hops between terminals and networks.

[0008] In addition, standardization of system architecture / service fields for satellite communication optimization methods, 5G system energy usage management and efficiency, SBI-based user plane evolution, ambient IoT technology, data service provision methods in IMS (IP multimedia subsystem), and avatar communication service persists. When such 5G mobile communication systems are commercialized, a vast increase in devices connected to the communication network will be realized, and accordingly, it is expected that the functions and performance of 5G mobile communication systems will be strengthened and integrated operation of connected devices will be required. To this end, new research will be additionally conducted on XR to efficiently support augmented reality (AR), virtual reality (VR), and mixed reality (MR), 5G performance improvement and complexity reduction using AI / ML, AI service support, metaverse service support, and drone communication.

[0009] The development of these 5G mobile communication systems is expected to serve as the basis for enhancing 5G performance and ultimately evolving into 6G. In the 6G era, eMBB, URLLC, and mMTC services, are expected to evolve into immersive communication (IC), hyper-reliable and low-latency communication (HRLLC), and massive communication (MC) services, respectively. In addition, new services such as AI and communication, integrated sensing and communication, and ubiquitous connectivity are expected to be additionally supported. For these 6G services, improved performance requirements compared to 5G are also essential, and standardization to define these is also in progress.

[0010] In this manner, to satisfy the expanded services and improved performance requirements of 6G, it is expected that it will be essential to optimize and improve system operation, such as introducing AI technology, improving energy efficiency, expanding coverage, and applying next-generation security technology, as well as developing sustainable communication technology, in addition to simply improving existing communication performance.

[0011] To this end, the latest AI technology is applied to all areas from the communication system design stage to development, management, and operation to improve communication performance and realize AI internalization technology that realizes network automation and efficiency, technology that improves user-perceived performance and network operation efficiency by improving power consumption of networks and terminals, technology that reduces power consumption in core base station components such as radio frequency (RF) and modems and in the channel coding and signal modulation and transmission / reception processes, multi-antenna transmission technology (e.g., extreme MIMO (X-MIMO)) that utilizes large antennas to overcome propagation path loss due to high frequency compared to the 3.5 GHz band of 5G communication and provide equivalent coverage, transmission / reception technology based on multiple base stations (e.g., distributed MIMO (D-MIMO)) to improve quality in cell edge areas, full-duplex communication (e.g., SBFD) technology to improve frequency efficiency and system network, next-generation encryption technology (e.g., post quantum cryptography (PQC)) and zero trust architecture (ZTA) technology to strengthen 6G communication security, and initial access delay and mobility. Research will be focused on technologies to minimize delay, design a hardware-friendly protocol structure for ultra-high-speed data processing, and expand the application of integrity protection technologies.

[0012] In addition, research will be conducted on the structure of mobile communication systems (prevention of redundant functions, simplification of functions, etc.), introduction of new planes for providing service providers, user privacy protection measures, realistic services, enhancement of network resiliency, network sharing technologies, improved security technologies (false base stations, lower layer protection, etc.), and intent-based network operation and management.

[0013] In recent years, Non-Terrestrial Network (NTN) and Air-To-Ground (ATG) networks have been considered and their operation integrated into 3GPP systems in order to enhance coverage and / or provide alternative coverage mechanisms.

[0014] The disclosure relates generally to wireless communication systems and, more specifically, the disclosure relates to a wireless communication in NTN system.

[0015] Accordingly, an aspect of the disclosure is to provide methods and apparatus for configuring and reporting measurements of NTN cells performed in RRC idle and RRC inactive modes(or states), that allows a UE to perform measurements of NTN cells before the UE enters RRC connected mode.

[0016] The technical problems to be achieved in the various examples of the present disclosure are not limited to those mentioned above, and other technical problems not mentioned can be considered by a person having ordinary skill in the art from the various examples of the present disclosure described below.

[0017] According to an example of the disclosure, a method performed by a terminal in a wireless communication system is provided. The method may include: receiving, from a base station, non-terrestrial network (NTN) measurement configuration information for performing NTN measurement; performing a measurement on an NTN cell, the terminal being in a radio resource control (RRC) idle state or RRC inactive state; entering an RRC connected state; and transmitting, to the base station, a result of the measurement.

[0018] Furthermore, according to an example of the disclosure, a method performed by a base station in a wireless communication system is provided. The method may include: transmitting, to a terminal, non-terrestrial network (NTN) measurement configuration information for performing NTN measurement; and receiving, from the terminal, a result of a measurement on an NTN cell, wherein the measurement is performed in a radio resource control (RRC) idle state or RRC inactive state of the terminal, and wherein the result is transmitted after entering an RRC connected state.

[0019] In accordance with an aspect of the disclosure, a terminal in a wireless communication system is provided. The terminal may includes: at least one transceiver; at least one processor communicatively coupled to the at least one transceiver; and at least one memory communicatively coupled to the at least one processor and storing instruction executable by the at least one processor, wherein the instructions cause the terminal to: receive, from a base station, non-terrestrial network (NTN) measurement configuration information for performing NTN measurement, perform a measurement on an NTN cell, the terminal being in a radio resource control (RRC) idle state or RRC inactive state, enter an RRC connected state, and transmit, to the base station, a result of the measurement.

[0020] In accordance with an aspect of the disclosure, a base station in a wireless communication system is provided. The base station may includes: at least one transceiver; at least one processor communicatively coupled to the at least one transceiver; and at least one memory communicatively coupled to the at least one processor and storing instructions executable by the at least one processor, wherein the instructions cause the base station to: transmit, to a terminal, non-terrestrial network (NTN) measurement configuration information for performing NTN measurement, and receive, from the terminal, a result of a measurement on an NTN cell, wherein the measurement is performed in a radio resource control (RRC) idle state or RRC inactive state of the terminal, and wherein the result is transmitted after entering an RRC connected state.

[0021] In accordance with an aspect of the present disclosure, there is provided a method for performing non-terrestrial network (NTN) measurements by a user equipment (UE) in a mobile communications system, the method comprising: receiving, by the UE from a serving cell, NTN measurement configuration information for performing NTN measurements; performing, by the UE when in a radio resource control (RRC) idle mode or RRC inactive mode, one or more measurements on an NTN cell and / or an NTN frequency; reporting, from the UE to the serving cell, the one or more NTN measurements.

[0022] In an example, the method further comprises entering, by the UE, an RRC connected mode, and wherein the reporting is performed in the RRC connected mode.

[0023] In an example, the NTN measurement configuration information is received by the UE when the UE is an RRC connected mode.

[0024] In an example, the NTN measurement configuration information is received by the UE in broadcast signaling and / or dedicated signaling.

[0025] In an example, the NTN measurement configuration information includes NTN assistance information.

[0026] In an example, the NTN assistance information includes one or more of ephemeris information, timing information, and satellite ID information.

[0027] In an example, the method further comprises transmitting, from the UE to the serving cell, an NTN measurement capability indication.

[0028] In an example, the NTN measurement capability indication indicates whether the UE is capable / permitted / configured to perform NTN measurements in an RRC idle or RRC inactive modes.

[0029] In an example, the NTN measurement capability indication indicates one or more of a frequency band and a RAT the UE is capable of performing NTN measurements on.

[0030] In an example, the one or more NTN measurements are performed if the UE is within a validity area and / or a coverage area of one or more NTN cells.

[0031] In an example, the one or more NTN measurements are performed based on the UE having valid position information.

[0032] In an example, the one or more NTN measurements are performed based on the serving cell satisfying one or more conditions.

[0033] In an example, the one or more NTN measurements are reported based on the serving cell satisfying one or more conditions.

[0034] In an example, UE location information is reported with the one or more NTN measurements.

[0035] In an example, the method further comprises transmitting, from the UE to the serving cell, an indication of the availability of the one or more NTN measurements.

[0036] In an example, UE is configured to perform and / or report NTN measurements on one or more specific NTN cells.

[0037] In an example, the one or more NTN measurements reported to the serving cell include NTN measurements that satisfy a certain condition.

[0038] In an example, the one or more NTN measurements are reported to the serving cell in an RRC message.

[0039] In an example, the reported NTN measurements include measurements on NTN cells for which the UE has valid ephemeris information.

[0040] In an example, the serving cell includes an E-UTRAN cell, an eMTC NTN cell, a NR cell, or a NR NTN cell.

[0041] In an example, the NTN cell includes a NB-IoT NTN cell, an eMTC NTN cell, a 6G IoT NTN cell, or a 5G NR NTN cell.

[0042] According to an aspect of the disclosure, there is provided a user equipment configured to perform the method of any preceding aspect or example.

[0043] The various examples of the disclosure described above are only some of the preferred examples of the disclosure, and various examples reflecting the technical features of the various examples of the disclosure can be derived and understood by a person having ordinary skill in the art based on the detailed description to be described below.

[0044] According to examples of the disclosure, in an NTN system, the base station can receive measurement reports from the UE more promptly, by enabling rapid execution of operations such as carrier aggregation (CA) and handover (HO) while reducing service interruption.

[0045] Furthermore, according to an examples of the disclosure, by performing pre-measurement of NTN cells in RRC Idle / Inactive and allowing the UE to immediately report the results after entering the RRC connected state, initial configuration latency is shortened and signaling / measurement-gap overhead during connected-mode data scheduling is mitigated.

[0046] In addition, according to an examples of the disclosure, power consumption associated with repeated measurement configuration and location acquisition in connected mode is reduced at the UE, improving energy efficiency while maintaining the quality of service (QoS) during NTN / TN integration.

[0047] The effects that can be obtained from the disclosure are not limited to the effects mentioned in the various examples, and other effects that are not mentioned can be clearly understood by a person having ordinary skill in the art to which the disclosure belongs from the description below.

[0048] Examples of the disclosure are further described hereinafter with reference to the accompanying drawings, in which:

[0049] Figure 1a illustrates an example of NTN in a wireless communication system;

[0050] Figure 1b illustrates another example of NTN in a wireless communication system;

[0051] Figure 2 illustrates examples of system information acquisition by an IoT NTN UE and NR NTN UE;

[0052] Figure 3a illustrates an example of RRC setup procedure;

[0053] Figure 3b illustrates an example of RRC resume procedure;

[0054] Figure 4a illustrates an example of carrier aggregation establishment procedure;

[0055] Figure 4b illustrates an example of measurement and measurement reporting for carrier aggregation;

[0056] Figure 5 illustrates an example of performing and reporting NTN measurements; and

[0057] Figure 6 illustrates a block diagram of an exemplary network entity / function that may be used in certain examples of the disclosure.

[0058] Hereinafter, embodiments of the disclosure will be described in detail with reference to the accompanying drawings.

[0059] In describing the embodiments, descriptions related to technical contents well-known in the art and not associated directly with the disclosure will be omitted. Such an omission of unnecessary descriptions is intended to prevent obscuring of the main idea of the disclosure and more clearly transfer the main idea.

[0060] For the same reason, in the accompanying drawings, some elements may be exaggerated, omitted, or schematically illustrated. Further, the size of each element does not completely reflect the actual size. In the drawings, identical or corresponding elements are provided with identical reference numerals or different reference numerals.

[0061] The advantages and features of the disclosure and ways to achieve them will be apparent by making reference to embodiments as described below in detail in conjunction with the accompanying drawings. However, the disclosure is not limited to the embodiments set forth below, but may be implemented in various different forms. The following embodiments are provided only to completely disclose the disclosure and inform those skilled in the art of the scope of the disclosure, and the disclosure is defined only by the scope of the appended claims. Throughout the specification, the same or like reference numerals designate the same or like elements. Furthermore, in describing the disclosure, a detailed description of known functions or constitution incorporated herein will be omitted in the case that it is determined that the description may make the subject matter of the disclosure unnecessarily unclear. The terms which will be described below are terms defined in consideration of the functions in the disclosure, and may be different according to users, intentions of the operators, or customs. Therefore, the definitions of the terms should be made based on the contents throughout the specification.

[0062] Herein, it will be understood that each block of the flowchart illustrations, and combinations of blocks in the flowchart illustrations, may be performed based on computer program instructions. These computer program instructions may be loaded collectively onto at least one processor of a general purpose computer, special purpose computer, or other programmable data processing apparatus to produce a machine, such that the instructions, which perform through any one of, or in any combination of, the at least one processor of the computer or other programmable data processing apparatus, create means for performing the functions specified in the flowchart block(s). These computer program instructions may also be stored in a non-transitory computer usable or computer-readable memory that may direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer usable or computer-readable memory produce an article of manufacture including instruction means that perform the function specified in the flowchart block(s). The computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable data processing apparatus to produce a computer executed process such that the instructions that perform on the computer or other programmable data processing apparatus provide steps for executing the functions specified in the flowchart block(s).

[0063] Further, each block may represent a module, segment, or portion of code, which includes one or more executable instructions for executing the specified logical function(s). It should also be noted that in some alternative implementations, the functions noted in the blocks may occur out of the order. For example, two blocks(or functions) shown in succession may in fact be performed substantially concurrently or the blocks may sometimes be performed in the reverse order, depending upon the functionality involved.

[0064] As used in embodiments of the disclosure, a "~unit" may refer to a software element or a hardware element, such as a field programmable gate array (FPGA) or an application specific integrated circuit (ASIC), which performs a predetermined function. However, the term including the word "~unit" does not always have a meaning limited to software or hardware. The "~unit" may be constructed either to be stored in an addressable storage medium or to execute one or more processors. Therefore, the "~unit" includes, for example, software elements, object-oriented software elements, components such as class elements and task elements, processes, functions, properties, procedures, sub-routines, segments of a program code, drivers, firmware, micro-codes, circuits, data, database, data structures, tables, arrays, and parameters. The components and functions provided by the "~unit" may be either combined into a smaller number of components and a "~unit," or divided into additional components and a "~unit." Moreover, the components and "~units" may be implemented to reproduce one or more central processing units (CPUs) within a device or a security multimedia card. Further, in the embodiments, the "unit" may include one or more processors.

[0065] It should be appreciated that the blocks in each flowchart and combinations of the flowcharts may be performed by one or more computer programs which include instructions. The entirety of the one or more computer programs may be stored in a single memory device or the one or more computer programs may be divided with different portions stored in different multiple memory devices.

[0066] Any of the functions or operations described herein can be processed by one processor or a combination of processors. The one processor or the combination of processors is circuitry performing processing and includes circuitry like an application processor (AP, e.g. a CPU), a communication processor (CP, e.g., a modem), a graphics processing unit (GPU), a neural processing unit (NPU) (e.g., an artificial intelligence (AI) chip), a Wi-Fi chip, a Bluetooth® chip, a global positioning system (GPS) chip, a near field communication (NFC) chip, connectivity chips, a sensor controller, a touch controller, a finger-print sensor controller, a display driver integrated circuit (IC), an audio CODEC chip, a universal serial bus (USB) controller, a camera controller, an image processing IC, a microprocessor unit (MPU), a system on chip (SoC), an IC, or the like.

[0067] It will be appreciated that various embodiments of the disclosure according to the claims and description in the specification can be realized in the form of hardware, software or a combination of hardware and software.

[0068] Any such software may be stored in non-transitory computer readable storage media. The non-transitory computer readable storage media store one or more computer programs (software modules), the one or more computer programs include computer-executable instructions that, when executed by one or more processors of an electronic device individually or collectively, cause the electronic device to perform a method of the disclosure.

[0069] Any such software may be stored in the form of volatile or non-volatile storage such as, for example, a storage device like read only memory (ROM), whether erasable or rewritable or not, or in the form of memory such as, for example, random access memory (RAM), memory chips, device or integrated circuits or on an optically or magnetically readable medium such as, for example, a compact disk (CD), digital versatile disc (DVD), magnetic disk or magnetic tape or the like. It will be appreciated that the storage devices and storage media are various embodiments of non-transitory machine-readable storage that are suitable for storing a computer program or computer programs comprising instructions that, when executed, implement various embodiments of the disclosure. Accordingly, various embodiments of the present disclosure may provide a program comprising code for implementing apparatus or a method as claimed in any one of the claims of this specification and a non-transitory machine-readable storage storing such a program.

[0070] Hereinafter, the determination of priority between A and B in the present disclosure may refer to various actions such as selecting the one having a higher priority based on a predefined priority rule and performing an operation corresponding thereto, or omitting or dropping an operation corresponding to the one having a lower priority.

[0071] Hereinafter, "A or B" as described in the present disclosure may be understood as "A and / or B," which may include A, or B, or both A and B.

[0072] In addition, "at least one of A, B, and C" as described in the present disclosure may be understood to include A, or B, or C, or any combination of A, B, and C.

[0073] In addition, "at least one of A, B, or C" as described in the present disclosure may be understood to include A, or B, or C, or any combination of A, B, and C.

[0074] Furthermore, "A / B" as described in the present disclosure may be understood as "A and / or B," which may include A, or B, or both A and B.

[0075] Furthermore, "A, B" as described in the present disclosure may be understood as "A and / or B," which may include A, or B, or both A and B.

[0076] Furthermore, "A and B" as described in the present disclosure may be understood as "A and / or B," which may include A, or B, or both A and B.

[0077] Furthermore, "if condition A and condition B are satisfied," as described in the present disclosure, may not be limited to a case where both condition A and condition B are satisfied, but may be understood to include a case where either condition A or condition B is individually satisfied, both condition A and condition B are satisfied, or one or more additional conditions are satisfied in combination.

[0078] Furthermore, the terms "first ~", "second ~", etc., as described in the present disclosure with respect to various elements (e.g., information, objects, operation, sequences, or the like), should not limit those elements. These terms may only be intended to distinguish one element from another, and may not be intended to indicate a specific order. For example, a first element could be termed a second element, and, similarly, a second element could be termed a first element.

[0079] Furthermore, even if "first ~" and "second ~" are described in the present disclosure, it may be understood that element(s) referred to by "first ~" and "second ~" may be the same or different. For example, in case of element(s) being information, first information and second information may both be information and, in some cases, are separate and different information.

[0080] In addition, the terms "if ~" and "in case that ~" as used in the disclosure or claims may be interpreted to include the meanings of "when (or upon) ~," "in response to ~," "based on ~," or "according to ~," and may be used interchangeably with these expressions. In addition, expressions other than those exemplified herein may also be used, as long as they have substantially the same meaning and do not impair the technical features of the present disclosure.

[0081] For example, the physical layer signaling may be referred to as Layer 1 (L1) signaling and may include downlink control information (DCI). In addition, the higher layer signaling may include a medium access control (MAC) control message, a radio resource control (RRC) signaling message, a non-access stratum (NAS) signaling message, or an application layer message. The RRC signaling message may be referred to as L3 (layer 3) signaling. It should be noted, however, that the higher layer signaling is not limited to the aforementioned examples.

[0082] In addition, the term "not perform" as used in the present disclosure or claims may, in context, be understood to mean that the corresponding step is omitted or skipped. Such a term may be replaced with other terms having the same or substantially equivalent meaning.

[0083] In addition, "transmitting a message including A and B" as described in the present disclosure, may be understood as encompassing both (i) transmitting A and B in a single message, and (ii) transmitting A and B separately via multiple messages (e.g., transmitting a first message including A and a second message including B). This interpretation may also apply to messages that include two or more items (e.g., A, B, C), transmitted either together or separately.

[0084] In addition, "transmitting a message including A and transmitting a message including B" may also be interpreted as transmitting a message including A and B in a single message.

[0085] In the specific embodiments of the present disclosure described below, terms or components included in the disclosure may be expressed in singular or plural form depending on the specific embodiments presented. However, such singular or plural expressions are selected appropriately for convenience of description, and the present disclosure is not limited to a singular or plural number of components. A component expressed in the plural form may be implemented as a single component, and a component expressed in the singular form may be implemented as multiple components.

[0086] The drawings or flowcharts described below illustrate exemplary methods that may be implemented according to the principles of the present disclosure, and various modifications may be made to the methods illustrated in the flowcharts of the present disclosure. For example, although illustrated as a series of steps, various steps in each drawing or flowchart may overlap, occur in parallel, occur in a different order, or be repeated. In other examples, any step may be omitted or replaced with another step.

[0087] The methods and apparatuses proposed in the embodiments of the present disclosure are not limited to each embodiment individually, but may also be applied in combination of all or some of the embodiments proposed in the disclosure. Therefore, the embodiments of the present disclosure may be modified and applied without significantly departing from the scope of the present disclosure, as would be understood by those skilled in the art.

[0088] In this case, even if certain wordings are described differently across embodiments, they may be used interchangeably or in substitution or in combination if their underlying concepts are equivalent. For example, for the same or equivalent concept, even if one embodiment uses the expression "A" and another embodiment uses the expression "B", such expressions may be understood interchangeably, in substitution, or in combination.

[0089] The terms used in the following description to refer to access nodes, network entities, messages, interfaces between network entities, various types of identification information, and the like, are provided merely for the convenience of explanation by way of example. Therefore, the present disclosure is not limited to the terms described below, and other terms having equivalent technical meanings may also be used. Such terms may also be interchangeable with terms defined in any 3rd generation partnership project　(3GPP) technical specifications (TS) where appropriate.

[0090] Hereinafter, a base station is an entity that allocates resources to terminals, and may be at least one of a gNode B, an eNode B, a Node B, a base station (BS), a wireless access unit, a BS controller, or a node on a network.

[0091] Furthermore, the base station of the present disclosure may include a split architecture comprising a central unit (CU) and a distributed unit (DU). In this structure, the CU is configured to process the higher layers of the control and user planes, while the DU is configured to process lower-layer radio resource functions. The embodiments of the present disclosure may be equally applicable to 5G base station architectures in which such CU and DU functional splits are implemented.

[0092] A terminal may include a UE, a mobile station (MS), a cellular phone, a smartphone, a computer, or a multimedia system capable of performing communication functions.

[0093] In the disclosure, a downlink (DL) refers to a radio link through which a BS transmits a signal to a UE, and an uplink (UL) refers to a radio link through which a UE transmits a signal to a BS.

[0094] Furthermore, hereinafter, 5th generation (5G) mobile communication technologies (e.g., 5G new radio (NR)), 6th generation (6G) mobile communication technologies may be described by way of example, but the embodiments of the present disclosure may also be applied to other communication systems having similar technical backgrounds or channel types. For example, newly evolved mobile communication systems developed after 5G and 6G may be included. Furthermore, based on determinations by those skilled in the art, the embodiments of the present disclosure may also be applied to other communication systems (e.g., Wi-Fi systems) through some modifications without significantly departing from the scope of the present disclosure

[0095] In the following description, the terms physical channel and signal may be used interchangeably with data or control signal. For example, the term physical downlink shared channel (PDSCH) refers to a physical channel through which data is transmitted, but the term PDSCH may also be used to refer to the data itself. That is, in the present disclosure, the expression "transmit a physical channel" may be interpreted as being equivalent to the expression "transmit data or a signal via a physical channel."

[0096] Hereinafter, in the context of the present disclosure, higher layer signaling may refer to signaling corresponding to at least one or any combination of the following: master information block (MIB), system information block (SIB) or SIB X (X = 1, 2, ...), radio resource control (RRC), or medium access control (MAC) control element (CE), or a non-access stratum (NAS) signaling message, or an application layer message. The RRC signaling message may be referred to as L3 (layer 3) signaling.

[0097] In addition, L1 signaling may refer to signaling corresponding to at least one or any combination of signaling techniques using the at least one or any combination of the following physical layer channels or signaling: physical downlink control channel (PDCCH), downlink control information (DCI), user equipment (UE)-specific DCI, group-common DCI, common DCI, scheduling DCI (e.g., DCI used for scheduling downlink or uplink data), non-scheduling DCI (e.g., DCI not used for scheduling downlink or uplink data) physical uplink control channel (PUCCH), or uplink control information (UCI). The L1 signaling message may be referred to as a physical layer signaling.

[0098] Hereinafter, the expression that information is configured by the BS, as used in the present disclosure or claims, may, in context, be understood to mean that the terminal receives the corresponding information from the BS via a physical layer signaling or a higher layer signaling. Such an expression may be replaced with other terms having the same or substantially equivalent meaning.

[0099] Hereinafter, the operational principle of the present disclosure will be described in detail with reference to the accompanying drawings.

[0100] The following examples are applicable to, and use terminology associated with, 3GPP 4G (e.g., LTE) and / or 5G (e.g., NR). However, the skilled person will appreciate that the techniques disclosed herein are not limited to these examples or to 3GPP 4G (e.g., LTE) and / or 5G (e.g., NR), and may be applied in any suitable system or standard, for example one or more existing and / or future generation wireless communication systems or standards (e.g., B5G, 5G-Advanced, 6G etc.). The skilled person will appreciate that the techniques disclosed herein may be applied in any existing or future releases of 3GPP 4G (e.g., LTE) and / or 5G (e.g., NR) and / or 5G Advanced and / or 6G, and / or (3GPP Release 17, 18, 19, 20, etc.) or any other relevant standard. For example, the functionality of the various network entities and other features disclosed herein may be applied to corresponding or equivalent entities or features in other communication systems or standards. Corresponding or equivalent entities or features may be regarded as entities or features that perform the same or similar role, function, operation or purpose within the network.

[0101] Furthermore, the following also applies to the disclosure:

[0102] ● The terms functionality / use-case / configuration / scenario / site may be used interchangeably.

[0103] ● The terms model and model functionality may be used interchangeably.

[0104] ● This disclosure also apply to non-3GPP entities.

[0105] ● The concepts, proposals, solutions, methods, embodiments, figures, and / or examples, presented in this disclosure, would apply to various type of communication systems, such as 4G, 4G-Advanced, 5G, 5G-Advanced, and 6G.

[0106] A particular network entity may be implemented as a network element on dedicated hardware, as a software instance running on a dedicated hardware, and / or as a virtualised function instantiated on an appropriate platform, e.g. on a cloud infrastructure.

[0107] The skilled person will appreciate that the disclosure is not limited to the specific examples disclosed herein. For example:

[0108] ● The techniques disclosed herein are not limited to 3GPP 4G or 5G or 5G-Advanced and also apply to B5G and 6G systems.

[0109] ● One or more entities in the examples disclosed herein may be replaced with one or more alternative entities performing equivalent or corresponding functions, processes or operations.

[0110] ● One or more of the messages in the examples disclosed herein may be replaced with one or more alternative messages, signals or other type of information carriers that communicate equivalent or corresponding information.

[0111] ● One or more further elements, entities and / or messages may be added to the examples disclosed herein.

[0112] ● One or more non-essential elements, entities and / or messages may be omitted in certain examples.

[0113] ● The functions, processes or operations of a particular entity in one example may be divided between two or more separate entities in an alternative example.

[0114] ● The functions, processes or operations of two or more separate entities in one example may be performed by a single entity in an alternative example.

[0115] ● Information carried by a particular message in one example may be carried by two or more separate messages in an alternative example.

[0116] ● Information carried by two or more separate messages in one example may be carried by a single message in an alternative example.

[0117] ● The order in which operations are performed may be modified, if possible, in alternative examples.

[0118] ● The transmission of information between network entities is not limited to the specific form, type and / or order of messages described in relation to the examples disclosed herein.

[0119] The approaches provided by the disclosure should also be taken in consideration of the following:

[0120] Ephemeris is not only applicable for satellite payloads, but can also apply to other platforms such a HAPS (High Altitude Platform Systems). Thus any mention of "satellite ephemeris" may not only apply to satellites but also other NTN platforms and / or payloads.

[0121] While the disclosed approaches are mostly described in terms of 5G NR, all approaches, proposals, embodiments, and examples may also apply to (4G) eNBs NG-eNBs (eNBs connected via 5GC) and 4G UEs. They may also apply to IoT technologies such as NB-IoT UEs, or LTE-M or eMTC UEs. Furthermore, the disclosed approaches apply to all related, newly defined, and / or existing signalling, such as: RRC signaling and / or messages, X2, Xn, S1, NG, and / or F1 signaling and messages, and / or related network entities (e.g. MME, AMF, other). For instance, if a measurement object is mentioned, it can be a measurement object for E-UTRAN or for NR, i.e. MeasObjectEUTRA or MeasObjectNR. It may also apply to any type of 6G technology.

[0122] Non-Terrestrial Networks (NTNs)

[0123] NR NTN (NR_NTN_solutions-Core) [RP-211557] was a 3GPP Work Item in 3GPP Release 17 to define solutions to enable New Radio (NR) and NG-RAN to support NTN. It addressed solutions for transparent payload for both Geostationary and non-Geostationary network scenarios, with the UE having Global Navigation Satellite System (GNSS) capability and the satellite beams being both earth-fixed or earth-moving.

[0124] Figure 1a illustrates an example of NTN in a wireless communication system. As illustrated in Figure 1a, an example NTN where a gateway (GW) 106 provides a feeder link 108 to a satellite 110 and the satellite provides an NTN cell 114 and an access link 116 to a device, such as a UE, within the NTN cell. The gateway may be connected to a gNB / eNB 104 which in turn is connected to a core network 102. The gateway 106 may be part of the gNB / eNB 104, separate to or partially integrated. This configuration may be referred to as a transparent payload scenario.

[0125] Figure 1b illustrates another example of NTN in a wireless communication system. As illustrated in Figure 1b, an example NTN is similar to that of Figure 1a but where at least some of the functions of the gNB / eNB 104 are implemented in the satellite 110. This configuration may be referred to as a regenerative payload scenario, which is considered in 3GPP release 19.

[0126] Internet of Things (IoT) NTN was a 3GPP study and work item in 3GPP release 17 to provide NTN access for E-UTRAN IoT devices (NB-IoT and LTE-M / eMTC) [RP-202689]. NR NTN was a work item in Rel-17 to specify adaptation to allow NR to function over NTN [RP-211557]. NTN access may be through Lower Earth Orbit (LEO), Medium Earth Orbit (MEO) and Geostationary Orbit (GEO), as well as through High-Altitude Platform Systems (HAPS).

[0127] Following the work items in Release 17 there were work items to enhance NR NTN [RP-220953] and IoT NTN [RP-220979] in Release 18.

[0128] NR NTN phase 3 [RP-234078] is a 3GPP Work Item in 3GPP Release 19 aiming to enhance NR NTN with a range of enhancements, such as downlink coverage enhancements, uplink capacity and throughout enhancements by using orthogonal coverage codes, multimedia broadcast service (MBS) broadcast over NTN, support, introduction of regenerative payload, and reduced capability (redcap) and NTN enhancements, and terrestrial E-UTRAN to NR NTN mobility, for example.

[0129] Air-to-Ground

[0130] Air-To-Ground was a 3GPP work item in 3GPP Release 18 to define solutions to enable 5G NR support in an Air-to-Ground scenario.

[0131] NTNSystem Information

[0132] As NTN has a number of NTN-specific information elements that are only required when accessing an NTN cell, and also due to the large information elements it was agreed that new system information blocks (SIB) were needed.

[0133] In NR NTN SIB19 contains the required information to access an NTN cell, as shown in Table 1 below:

[0134]

[0135] In IoT NTN SIB31 contains the required information to access an IoT NTN cell, as shown in Table 2 below:

[0136]

[0137] The system information contains the following:

[0138] - Serving cell Ephemeris elements- which allows UE to calculate the satellite position for doppler and time pre-compensation. This can be of two formats:

[0139] ○ PVT format - which describes a (X,Y,Z) position as well as a speed vector (vX, vY, vZ)

[0140] ○ Orbital parameters - this describes the orbital movements of the satellite which is then used to infer the satellite position

[0141] -TAcommon parameters- this provides the common timing advance parameters which is introduced to compensate for the feeder link delays. The signaling consists of (in total taking up 57 bits)

[0142] ○ Absolute TA common, taking up 23 bits

[0143] ○ Drift of the TA common - how the TA common drifts, i.e. the first derivative, taking up 19 bits

[0144] ○ Variation of the TA common - how the TA common varies, i.e. the second derivative of the TA common, taking up 15 bits

[0145] - Synchronization validity duration- used to define how long the ephemeris and TA common is valid

[0146] - Epoch time- when the synchronization validity duration should start

[0147] - K-Offset- scheduling offset for timing relationship in NTN

[0148] - K-Mac- Scheduling offset used when the downlink and uplink frame timing is not aligned

[0149] -NRNTNspecific information also include (as part of 38.331):

[0150] ○ T-Service (signaled in SIB3 in IoT NTN)

[0151] ○ Reference location and distance threshold - used for location-based measurement initiation in RRC IDLE and RRC Connected mode

[0152] ○ Neighbour cell ephemeris

[0153] ■ This is used for idle mode measurements

[0154] NTNSystem Information Acquisition

[0155] Figure 2 illustrates examples of system information acquisition by an IoT NTN UE and NR NTN UE.

[0156] As the ephemeris constantly changes due to the movement of the NTN node (e.g. satellite), the UE needs to read the system information. There is furthermore a timer (T317 in IoT NTN and T430 in 5G NTN) associated with the ephemeris element that is started every time the system information containing the ephemeris (SIB31 in IoT NTN and SIB19 in NR NTN) is read. In IoT NTN, when T317 expires, the UE is no longer considered synchronized and it will have to re-acquire SIB31 in order to stay synchronized. In NR NTN upon T430 expiry, the UE shall ensure that it has a recent ephemeris by reading the SIB in time by UE implementation. In IoT NTN, since an IoT UE (LTE-M and NB-IoT UE) is not expected to be able to acquire system information in connected mode, the UE tunes away and is likely unreachable while reading SIB31. If the IoT NTN UE is unable to read the SIB31 within a timer (T318) with a configured duration, the UE performs Radio Link Failure (RLF) similar to other cases where RLF is performed.

[0157] The NR NTN and IoT NTN timer operations can be seen in Figure 2. In Figure 2, an ephemeris information synchronization operation is shown, where in a) an IoT NTN UE successfully acquires the SIB31, b) where IoT NTN UE fails to read SIB31 during T318 which then expires and triggers RLF and c) where NR NTN UE acquires SIB19 before end of T430 timer.

[0158] The T317 timer is different compared to a normal timer in Radio Resource Control (RRC) as it is not started at having received the SIB31. This is because the ephemeris has an epoch time, which is the reference point in time of when the ephemeris is defined. Thus the T317 is started from the epoch time, which may be in the past or in the future relative to have received SIB31. This means that in a UE implementation, the timer may be started with a different value with what was signalled according to what was signalled in the fieldul-SyncValidityDurationin SIB31.

[0159] RRC States and Establishment Procedures

[0160] Figure 3a illustrates an example of RRC setup procedure and Figure 3b illustrates an example of RRC resume procedure.

[0161] RRC Setup is performed to bring a UE out of the RRC idle state (RRC_IDLE). This is triggered by the UE when there is uplink user or control plane data, or when receiving a Paging message. It consists of the following messages, which are illustrated in Figure 3a.

[0162] Whilst in RRC idle at 310, the UE 302 is triggered at 312 to enter RRC connected.

[0163] 1.RRCSetupRequest.This is the first message, sent by the UE at 314, which includes the UE identity and the establishment cause.

[0164] 2.RRCSetup.This the second message, sent by the network (e.g. gNB 304) at 316, which is the message that configures everything necessary in order to further communicate with the UE. This includes the master cell group configuration as well as the radio bearer configuration that configures SRB1.

[0165] 3.RRCSetupComplete. This is the response sent from the UE at 318 upon successfully receiving RRCSetup. This message may contain a number of different indications from the UE, such as a number of higher layer information, dedicated NAS message to forward to AMF, indications if the UE is a special type of UE (IAB, mIAB, NCR) etc. Also the UE may indicate whether it has measurements available.

[0166] The above steps highlight the message sent over RRC. It should be noted that the full procedure in RRC and MAC would also include MAC procedures which depends on the random access procedure. For 4-step random access procedure, which is the procedure introduced for the first release of 5G NR, the procedure would include a Msg1 and a Msg2. Msg1 consist of a preamble sent on the Random Access Channel (RACH), which is signals a number from 1 to 64 identifying the UE. Msg2 is the Random Access Response which contains a timing advance to synchronize the UE, as well as an uplink grant to send Msg3. Msg3 contains the RRCSetupRequest and Msg4 contains the RRCSetup as well as a contention resolution MAC CE to resolve any contention. For 2-step random access the MsgA consists of both the preamble and the RRCSetupRequest. MsgB consist of the random access response to synchronize the UE, an RRCSetup message as well as contention resolution.

[0167] It should be noted that MAC random access procedures are often independent of the RRC procedures, which means that the random access procedures may in general be the same for RRC Setup, RRC Resume, RRC Re-establishment and RRC reconfiguration with sync.

[0168] RRC Resume is performed to bring a UE out of the RRC inactive state. RRC Resume is start by the UE first synchronizing via random access and then transmitting RRCResumeRequest which contains the identifier of the UE, the i-RNTI, which is specifically used for RRC inactive. If the gNB is able to locate the UE context, i.e. the configuration of the UE, the gNB will reply with RRCResume, which may for instance contain a full configuration (else UE will used stored UE Inactive AS context for the connected mode configuration). The UE will restore security and the previous RRC configuration and then send the RRCResumeComplete, upon the procedure is completed the UE will have completed the RRC Resume procedures.

[0169] The RRC Resume procedures consist of the following messages, which are illustrated in Figure 3b.

[0170] Whilst in RRC connected, the network (e.g. gNB 354) sends to the UE 352 an RRCRelease with suspendConfig message at 356.

[0171] At 358 the UE enters RRC inactive in response to the received RRCRelease message.

[0172] At 360 the UE is triggered to perform RRC Resume (i.e. enter RRC connected).

[0173] 1.RRCResumeRequest. The UE sends this message at 362. This message contains the resume identity and the resume cause.

[0174] 2.RRCResume. The network sends this message at 364. This message can optionally contain a number of configurations to reconfigure the UE if necessary. It can further include specific commands or configurations such as whether UE shall restore SCells, whether to restore SCG, SCG configurations and more. It may also contain a request for UE to report idle mode measurements in RRCResumeComplete.

[0175] 3.RRCResumeComplete. The UE sends this message at 366. This message can similarly to RRCSetupComplete contain a number of indications from the UE.

[0176] The RRC resume procedure can be triggered in a number of ways:

[0177] - UE initiated:

[0178] ○ There is uplink traffic in the buffer. In this case the resume cause value used is mt-Access

[0179] ○ RAN Notification Area Update. This is triggered when the UE in RRC inactive camps on a cell which has a RAN-AreaCode which is not part of the UEs RAN Notification Area. The UEs RAN Notification Area is configured to a UE as part of the RRCRelease message when released to RRC inactive

[0180] ○ Expiry of timer T380, the periodic RAN Notification Area Update (RNAU) timer. In this case the cause value is rna-Update

[0181] Network-triggered

[0182] ○ UE receives a Paging message with a paging record matching its i-RNTI, i.e. a RAN-page

[0183] RRC Idle and RRC Inactive Mobility

[0184] Idle and inactive mode mobility is based on a UE autonomously performing measurements and deciding according to some rules whether a UE shall re-select to another cell or not to camp on.

[0185] During cell selection, the UE identifies suitable cells, which is according to a cell suitability criteria based on signal strength and signal quality measurements. After identifying one or several suitable cells, the UE can choose any of them.

[0186] During cell re-selection, the UE searches intra-frequency cells, inter-frequencies cells and inter-RAT cells. Each frequency will have a specific cell reselection priority, and the UE shall always choose a cell of highest priority, given that it is not barred or not allowed to camp on. If cells of equal priority is detected, then the UE shall rank all of the cells, where there ranking metric is based on signal strength and signal quality measurements and then choose the best candidate. The UE then camps on the newly re-selected cell.

[0187] RRC Idle and RRC Inactive Measurement Reporting

[0188] Figure 4a illustrates an example of carrier aggregation establishment procedure, and Figure 4b illustrates an example of measurement and measurement reporting for carrier aggregation.

[0189] Carrier aggregation is a key feature in 4G LTE and 5G NR, due to it enabling more bandwidth to be used, to achieve higher data rates and higher throughput. One of the issues of carrier aggregation in both 4G LTE and 5G NR is that a UE first only establishes connection to a single cell, i.e. to a single carrier. Adding more cells, i.e. more carriers to achieve higher throughput, is done by network reconfiguring the UE to add these cells. In order for the network to configure a set of new carriers to the UE, the network first needs to configure the UE to measure these carriers to determine whether it is suitable to establish carrier aggregation with these carriers. The main issue with this is that this procedure usually takes a lot of time, leading to relatively low utilization of carrier aggregation. And it should be noted that carrier aggregation would be beneficial even in cases where the data connection is relatively short.

[0190] The procedure of establishing carrier aggregation without enhancements can be seen in Figure 4a. It should be noted that Figure 4a is a simplified procedure for illustrative purposes and may include further steps.

[0191] The UE 402 when in RRC idle / inactive at 408 performs random access and RRC establishment procedures at 410 with a first gNB (e.g. gNB1 404).

[0192] At 412 the UE performs UE capability and security setup procedures with gNB1.

[0193] At 414 gNB1 configures the UE to measure other carriers / cells (e.g. gNB2 406) and the UE reports measurements.

[0194] At 416 the UE received from gNB1 an RRCReconfiguration message to establish other cells.

[0195] At 418 the UE establishes further cells on other carriers (e.g. with gNB2).

[0196] In Release 15 E-UTRAN and Release 16 NR, features were introduced to increase the utilization of carrier aggregation by attempting to speed up the carrier aggregation establishment. The main method for this is that a UE will measure other carriers in idle or inactive mode before accessing the cell, and then report these measurements during the establishment procedures, so that the UE should not need to perform measurements of these cells in connected mode. The general procedure can be seen in Figure 4b. It should be noted that Figure 4b is a simplified procedure for illustrative purposes and may include further steps.

[0197] The UE 452 when in RRC idle / inactive at 458 measures other carriers / cells (e.g. gNB2 456).

[0198] At 462 the UE performs random access and RRC establishment procedures at 410 with a first gNB (e.g. gNB1 454).

[0199] At 464 the UE reports to gNB1 the measurements of other carriers.

[0200] At 466 the UE received from gNB1 an RRCReconfiguration message to establish other cells.

[0201] At 468 the UE establishes further cells on other carriers (e.g. with gNB2).

[0202] The RRC idle and inactive measurements can either be configured when releasing a UE via RRC release, or it can be configured in a broadcasted manner via SIB11. The measurements can be indicated to be available by indicating in either RRCSetupComplete or RRCResumeComplete that they are available. The network then requests the messages via the UEInformationRequest and receives the measurements in UEInformationResponse message. An alternative manner of reporting the measurements, which is only possible when the UE performs the RRC resume procedure from RRC inactive, the network may request the UE to report the measurements in RRCResumeComplete by including a request (idleModeMeasurementReq) in the RRCResume message.

[0203] Despite the development of non-terrestrial networks, the integration of terrestrial and non-terrestrial networks still is not very mature. Some of the key problems when it comes to integration is the need to perform measurements to assess the signal strength of a terrestrial or non-terrestrial network. One of the issues is related to the need for a UE to have its own position determined before measuring a non-terrestrial cell.

[0204] For instance, when the UE is in RRC connected, there are still no performance requirements for performing measurements of a non-terrestrial cell when the UE is connected to a terrestrial cell. This is directly owing to the fact that performing the measurements are power consuming due to the need for the UE to have its own position. It is also due to the difficulty of managing the measurement gaps due to the relative movement in time.

[0205] The disclosure therefore addresses the problem of providing an improved approach to measurement and reporting of NTN cells.

[0206] RRC Idle and RRC InactiveNTNMeasurement and Reporting

[0207] Figure 5 illustrates a general approach for performing RRC Idle and RRC Inactive NTN measurement and reporting in accordance with the disclosure, where each step is expanded on below.

[0208] 0. At 506 the UE 502 optionally indicates to the network (e.g. gNB 504) capability to measure NTN in idle or inactive mode.

[0209] 1. At 508 the gNB 504 configures the UE 502 to measure NTN in idle or inactive mode.

[0210] 2. At 510 the UE 502 measures NTN cells or an NTN frequency in idle or inactive mode.

[0211] 3. At 512 the UE 502 is optionally triggered to perform RRC Setup or RRC resume, i.e. to establish an RRC connection with the gNB 504.

[0212] 4. At 514 the RRC Resume or RRC setup procedure is performed between the UE 502 and gNB 504.

[0213] 5. At 516 the UE 502 reports the NTN measurements to the gNB 504.

[0214] The UE may be configured to measure NTN cells in different scenarios, such as inter-RAT scenarios. Some examples include:

[0215] - An E-UTRAN cell or eNB configures a UE to measure and report IoT NTN cells in RRC idle and RRC inactive. The IoT NTN can be NB-IoT NTN, eMTC NTN or 6G IoT NTN.

[0216] - An E-UTRAN cell or eNB configures a UE to measure and report 5G NR NTN cells in RRC idle and RRC inactive.

[0217] - An eMTC NTN cell or eNB configures a UE to measure and report IoT NTN cells in RRC idle and RRC inactive.

[0218] - An NR cell or gNB configures a UE to measure and report NR NTN cells in RRC idle and RRC inactive.

[0219] - An NR cell or gNB configures a UE to measure and report IoT NTN cells in RRC idle and RRC inactive. The IoT NTN can be NB-IoT NTN, eMTC NTN or 6G IoT NTN.

[0220] - An NR NTN cell or gNB configures a UE to measure and report NR NTN cells in RRC idle and RRC inactive.

[0221] - As described above, the measurement and reporting may apply to when the cell configuring a UE to perform NTN measurements and to which the NTN measurements are reported is a terrestrial cell (i.e. a general TN-NTN scenario), and / or when the cell configuring a UE to perform NTN measurements and to which the NTN measurements are reported utilises a different RAT to the NTN cell (i.e. an inter-RAT TN-NTN scenario).

[0222] Although Figure 5 provides specific steps as part of the measurement and reporting procedure, certain steps may be omitted or amended, and / or additional steps introduced.

[0223] Note that configuring the UE to measure in RRC idle and inactive as described in this disclosure is different from performing measurements for the purpose of cell reselection. The measurements for cell reselection may for instance have different requirements and be used for different purposes.

[0224] The UE may report the capability to be configured and to perform the measurements in RRC idle and RRC inactive. This may for instance include which bands the UE is capable of performing the measurements, from and to which RAT that the UE is capable of performing the measurements in RRC idle and RRC inactive. It may also indicate which bands that the UE is capable of performing the above, or whether there are any restrictions.

[0225] ConfigureUEto MeasureNTNin RRC Idle and RRC Inactive

[0226] In order for the UE to measure NTN cells or a frequency with NTN cells, the UE may need to be appropriately configured.

[0227] In order for the UE to be able to easily measure an NTN cell, the UE may need to be configured with NTN assistance information. The NTN assistance information typically consists of ephemeris information or timing information such as TA common. The UE can be directly configured with the NTN assistance information in the RRC idle and inactive mode measurement configuration, which may be broadcasted or dedicatedly configured, or the UE may use other broadcasted NTN assistance information. The NTN assistance information may be configured per frequency or may be configured per NTN cell.

[0228] For instance, for utilizing other broadcasted NTN assistance information, the UE may be configured with a reference to such broadcasted NTN assistance information. For instance, for measuring from an E-UTRAN or IoT NTN cell, the UE may be configured with a list of satellite IDs, or any other IDs that identifies the ephemeris elements. The satellite ID may point to NTN assistance information in SIB31, SIB32 or SIB33. This may for instance work well for an E-UTRAN TN or IoT NTN cell configuring a UE to measure an IoT NTN cell or frequency or an NR NTN cell or frequency.

[0229] As an example, this means that a list of satellite IDs may be configured as part ofmeasIdleConfig, where a list of satellite IDs may be configured per carrier.

[0230] The UE may be configured to either apply the broadcasted NTN assistance information in SIB19 or SIB31 / SIB33 or to apply dedicated NTN assistance information, which may be a part of the idle and inactive measurement information. The UE may also be configured to apply broadcasted NTN assistance information for a first set of cells or frequencies and apply dedicated NTN assistance information for a second set of cells or frequencies.

[0231] It may be indicated in the configuration that the measured cell is an NTN cell or that the measured frequency is an NTN cell.

[0232] The validity area of the idle or inactive measurements may be defined to be based on the satelliteId of the cells. In other words, the UE shall only measure cells of certain satellite IDs.

[0233] The configuration may be configured as part of broadcasted or dedicated information. If configured as part of broadcasted information this may be a part of SIB11 by an NR cell and SIB5 by an E-UTRAN cell. If configured as part of dedicated information it can be configured via a message to release the UE, such as RRCRelease for NR or RRCConnectionRelease for E-UTRAN.

[0234] UEPerforms Measurements ofNTNin RRC Idle and RRC Inactive

[0235] In one aspect of the disclosure, the UE is only configured to measure NTN cells as long as the UE position, such as the UEs GNSS position is considered valid or up-to-date. If the UE position is out-dated, the UE may no longer be required to perform measurement of the NTN cell. This can for instance be decided by the GNSS validity duration of the UE. The UE may continue to measure if the UE once again performs a UE position measurement to determine or to update the UE position. The UE may be configured to perform GNSS position fix, or to otherwise acquire its location if the UE is able to quickly re-acquire its location. This can for instance be in the case where the GNSS is in a warm or hot state. This may mean that the UE would not have to re-acquire the GNSS location if the UE is in a cold state.

[0236] The UE may be configured to perform measurements of an NTN cell, a group of NTN cells or a frequency with NTN cells as long as the NTN assistance information is valid. The validity may be determined by the validity of the ephemeris elements, which means that when the ephemeris is no longer valid, then the UE may not need to measure the associated cells.

[0237] The UE may be configured with specific rules whether to attempt to measure NTN cells. For instance, the UE may be configured to only measure the NTN cells in RRC idle and RRC inactive if the signal strength with the cell that the UE is camping on is below some threshold, or if the signal strength to other neighbouring cells or frequency is below some type of threshold.

[0238] The UE may be configured to perform measurements of an NTN cell, a group of NTN cells or a frequency with NTN cells if the UE is far away from the base station. This can for instance be defined as the UE being more than a configured distance from a specific location, where the location may be configurable by the network. This can be configurable in the RRC idle and RRC inactive measurement configuration.

[0239] The UE may be configured to attempt to detect any NTN cell and report these detected NTN cells.

[0240] UEReports the Measurements Performed in RRC Idle and RRC Inactive

[0241] In one aspect of the disclosure, the UE reports the measurements of the NTN cells. The UE can be configured by the network to specifically report or not report the NTN cells.

[0242] The UE can be configured to report the RRC idle and RRC inactive measurements if the signal strength of the serving cell satisfies some condition, or if the NTN measurements satisfies some condition. These conditions may for instance be that the signal strength or signal quality is below or above some threshold.

[0243] In one aspect of the disclosure, the UE reports the detected NTN cells.

[0244] The UE may also include the UE location, for instance the coarse UE location, as part of the measurement result.

[0245] In order to report the measurements, the UE may indicate the availability of the measurements in an RRC message if configured to do so, or the UE may be configured to directly include the measurements in an RRC message. Example of RRC messages may be RRC(Connection)SetupComplete, RRC(Connection)ResumeComplete, RRC(Connection)ReestablishmentComplete or UEInformationResponse.

[0246] In one aspect of the disclosure, the UE does not report a measurement for a NTN cell or a satellite whose ephemeris is not valid or has expired. This can be very useful as a measurement from an NTN cell whose ephemeris that is no longer valid may not be useful to be reported.

[0247] If the UE did not attempt to perform any measurements of an NTN cell, group of NTN cells or an NTN frequency, for instance due to no UE location available or no accurate UE location available, or due to any other reason such as power saving mechanism, the UE may indicate this. In other words, the UE may be configured to indicate not having performed the configured NTN measurements.

[0248] Certain examples of the disclosure may be provided in the form of an apparatus / device / network entity configured to perform one or more defined network functions and / or a method therefor. Such an apparatus / device / network entity may comprise one or more elements, for example one or more of receivers, transmitters, transceivers, processors, controllers, modules, units, and the like, each element configured to perform one or more corresponding processes, operations and / or method steps for implementing the techniques described herein. For example, an operation / function of X may be performed by a module configured to perform X (or an X-module). Certain examples of the disclosure may be provided in the form of a system (e.g., a network) comprising one or more such apparatuses / devices / network entities, and / or a method therefor.

[0249] It will be appreciated that examples of the disclosure may be realized in the form of hardware, software or a combination of hardware and software. Certain examples of the disclosure may provide a computer program comprising instructions or code which, when executed, implement a method, system and / or apparatus in accordance with any aspect, example and / or embodiment disclosed herein. Certain embodiments of the disclosure provide a machine-readable storage storing such a program.

[0250] Example Changes to Specifications

[0251] Example changes to elements of certain 3GPP specifications are set out below, where the changes are shown in bold.

[0252] Example 1: Table 3

[0253]

[0254]

[0255] Example 2: Table 4

[0256]

[0257] Figure 6 is a block diagram of an exemplary network entity / function that may be used in examples of the disclosure, such as the techniques disclosed in relation to any of the preceding figures. For example, any of the network entities, network function etc. (e.g. UE, BS, gNB / eNB, ATG entities, NTN nodes, etc.) may be provided in the form of the network entity illustrated in Figure 6. The skilled person will appreciate that a network entity / function may be implemented, for example, as a network element on a dedicated hardware, as a software instance running on a dedicated hardware, and / or as a virtualised function instantiated on an appropriate platform, e.g. on a cloud infrastructure.

[0258] The entity 600 comprises a processor (or controller) 601, a transmitter 603 and a receiver 605. The receiver 605 is configured for receiving one or more messages from one or more other network entities, for example as described above. The transmitter 603 is configured for transmitting one or more messages to one or more other network entities, for example as described above. The processor 601 is configured for performing one or more operations, for example according to the operations as described above.

[0259] It will be appreciated that, in each example / embodiment / aspect etc. described above, one or more features or operations may be omitted, modified or moved (e.g., to change the order of the features or the operations), if desired and appropriate.

[0260] Additionally, where the figures illustrating example method flows include text in relation to a specific step / operation, it will be appreciated that this text is simply an example of the corresponding step / operation, where a more general definition (such as may be found in the description of the corresponding step) may apply for the step / operation.

[0261] Additionally, regarding all of the above, one or more features or operations etc. from any example / embodiment may be combined with features or operations from any other example / embodiment. That is, the disclosure should be considered to include all combinations of examples / embodiments disclosed herein, as appropriate, as well as combinations of individual features within and between each example / embodiment, as appropriate.

[0262] The techniques described herein may be implemented using any suitably configured apparatus and / or system. Such an apparatus and / or system may be configured to perform a method according to any aspect, embodiment or example disclosed herein. Such an apparatus may comprise one or more elements, for example one or more of receivers, transmitters, transceivers, processors, controllers, modules, units, and the like, each element configured to perform one or more corresponding processes, operations and / or method steps for implementing the techniques described herein. For example, an operation / function of X may be performed by a module configured to perform X (or an X-module). The one or more elements may be implemented in the form of hardware, software, or any combination of hardware and software.

[0263] It will be appreciated that examples of the disclosure may be implemented in the form of hardware, software or any combination of hardware and software. Any such software may be stored in the form of volatile or non-volatile storage, for example a storage device like a ROM, whether erasable or rewritable or not, or in the form of memory such as, for example, RAM, memory chips, device or integrated circuits or on an optically or magnetically readable medium such as, for example, a CD, DVD, magnetic disk or magnetic tape or the like.

[0264] It will be appreciated that the storage devices and storage media are embodiments of machine-readable storage that are suitable for storing a program or programs comprising instructions that, when executed, implement certain examples of the disclosure. Accordingly, certain examples provide a program comprising code for implementing a method, apparatus or system according to any example, embodiment and / or aspect disclosed herein, and / or a machine-readable storage storing such a program. Still further, such programs may be conveyed electronically via any medium, for example a communication signal carried over a wired or wireless connection.

[0265] While the disclosure has been shown and described with reference to certain examples, it will be understood by those skilled in the art that various changes in form and detail may be made therein without departing from the scope of the disclosure.

[0266] The reader's attention is directed to all papers and documents which are filed concurrently with or previous to this specification in connection with this application and which are open to public inspection with this specification, and the contents of all such papers and documents are incorporated herein by reference.

[0267]

[0268] Acronyms and Definitions: Table 5

[0269]

Claims

1.A method performed by a terminal in a wireless communication system, the method comprising:receiving, from a base station, non-terrestrial network (NTN) measurement configuration information for performing NTN measurement;performing a measurement on an NTN cell, the terminal being in a radio resource control (RRC) idle state or RRC inactive state;entering an RRC connected state; andtransmitting, to the base station, a result of the measurement.2.The method of Claim 1, further comprising:transmitting, to the base station, NTN measurement capability information including an indication that the terminal is capable of performing the NTN measurement in an RRC idle or RRC inactive state,wherein the NTN measurement capability information further includes at least one of information on a frequency band or information on a radio access technology (RAT) associated with the NTN measurement.3.The method of Claim 1,wherein the NTN measurement configuration information is received via broadcast signaling or dedicated signaling,wherein the NTN measurement configuration information includes NTN assistance information including at least one of ephemeris information, timing information, and satellite ID information, andwherein, in case that the NTN assistance information is valid and in case that the terminal is within a validity area and / or a coverage area associated with the NTN cell, the measurement is performed.4.The method of Claim 1, further comprising:transmitting, to the base station, an indication of an availability of the measurement,wherein the result of the measurement includes location information for the terminal,wherein, in case that a signal strength with a serving cell of the base station is below a threshold, the result of the measurement is transmitted, andwherein, in case that ephemeris of the NTN cell is not valid, the result of the measurement is not transmitted.5.A method performed by a base station in a wireless communication system, the method comprising:transmitting, to a terminal, non-terrestrial network (NTN) measurement configuration information for performing NTN measurement; andreceiving, from the terminal, a result of a measurement on an NTN cell,wherein the measurement is performed in a radio resource control (RRC) idle state or RRC inactive state of the terminal, andwherein the result is transmitted after entering an RRC connected state.6.The method of Claim 5, further comprising:receiving, from the terminal, NTN measurement capability information including an indication that the terminal is capable of performing the NTN measurement in an RRC idle or RRC inactive state,wherein the NTN measurement capability information further includes at least one of information on a frequency band or information on a radio access technology (RAT) associated with the NTN measurement,wherein the NTN measurement configuration information is transmitted via broadcast signaling or dedicated signaling,wherein the NTN measurement configuration information includes NTN assistance information including at least one of ephemeris information, timing information, and satellite ID information, andwherein, in case that the NTN assistance information is valid and in case that the terminal is within a validity area and / or a coverage area associated with the NTN cell, the measurement is performed.7.The method of Claim 5, further comprising:receiving, from the terminal, an indication of an availability of the measurement,wherein the result of the measurement includes location information for the terminal,wherein, in case that a signal strength with a serving cell of the base station is below a threshold, the result of the measurement is received, andwherein, in case that ephemeris of the NTN cell is not valid, the result of the measurement is not received.8.A terminal in a wireless communication system, the terminal comprising:at least one transceiver;at least one processor communicatively coupled to the at least one transceiver; andat least one memory communicatively coupled to the at least one processor and storing instruction executable by the at least one processor,wherein the instructions cause the terminal to:receive, from a base station, non-terrestrial network (NTN) measurement configuration information for performing NTN measurement,perform a measurement on an NTN cell, the terminal being in a radio resource control (RRC) idle state or RRC inactive state,enter an RRC connected state, andtransmit, to the base station, a result of the measurement.9.The terminal of Claim 8,wherein the instructions further cause the terminal to transmit, to the base station, NTN measurement capability information including an indication that the terminal is capable of performing the NTN measurement in an RRC idle or RRC inactive state,wherein the NTN measurement capability information further includes at least one of information on a frequency band or information on a radio access technology (RAT) associated with the NTN measurement.10.The terminal of Claim 8,wherein the NTN measurement configuration information is received via broadcast signaling or dedicated signaling,wherein the NTN measurement configuration information includes NTN assistance information including at least one of ephemeris information, timing information, and satellite ID information, andwherein, in case that the NTN assistance information is valid and in case that the terminal is within a validity area and / or a coverage area associated with the NTN cell, the measurement is performed.11.The terminal of Claim 8,wherein the instructions further cause the terminal to transmit, to the base station, an indication of an availability of the measurement,wherein the result of the measurement includes location information for the terminal,wherein, in case that a signal strength with a serving cell of the base station is below a threshold, the result of the measurement is transmitted, andwherein, in case that ephemeris of the NTN cell is not valid, the result of the measurement is not transmitted.12.A base station in a wireless communication system, the base station comprising:at least one transceiver;at least one processor communicatively coupled to the at least one transceiver; andat least one memory communicatively coupled to the at least one processor and storing instructions executable by the at least one processor,wherein the instructions cause the base station to:transmit, to a terminal, non-terrestrial network (NTN) measurement configuration information for performing NTN measurement, andreceive, from the terminal, a result of a measurement on an NTN cell,wherein the measurement is performed in a radio resource control (RRC) idle state or RRC inactive state of the terminal, andwherein the result is transmitted after entering an RRC connected state.13.The base station of Claim 12,wherein the instructions further cause the base station to receive, from the terminal, NTN measurement capability information including an indication that the terminal is capable of performing the NTN measurement in an RRC idle or RRC inactive state,wherein the NTN measurement capability information further includes at least one of information on a frequency band or information on a radio access technology (RAT) associated with NTN measurement,wherein the NTN measurement configuration information is transmitted via broadcast signaling or dedicated signaling,wherein the NTN measurement configuration information includes NTN assistance information including at least one of ephemeris information, timing information, and satellite ID information, andwherein, in case that the NTN assistance information is valid and in case that the terminal is within a validity area and / or a coverage area associated with the NTN cell, the measurement is performed.14.The base station of Claim 12,wherein the instructions further cause the base station to receive, from the terminal, an indication of an availability of the measurement,wherein the result of the measurement includes location information for the terminal,wherein, in case that a signal strength with a serving cell of the base station is below a threshold, the result of the measurement is received, andwherein, in case that ephemeris of the NTN cell is not valid, the result of the measurement is not received.

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