Providing neighbor cell information in non-terrestrial networks

Abstract

The present disclosure relates to a 5th-Generation (5G) or 6th-Generation (6G) communication system for supporting higher data transmission rates. A method performed by a user equipment (UE) in a wireless communication system is provided. The method includes receiving a first system information block (SIB) associated with satellite assistance information from a base station, the first SIB including first information about a serving cell ephemeris table and second information about an effective duration of a serving cell astronomical table, and receiving a second system information block (SIB) associated with the neighbor satellite information from the base station based on a first timer whose duration is an effective duration of the serving cell ephemeris and a second timer for obtaining the first SIB prior to a radio link failure (RLF), the second SIB including third information about the neighbor cell ephemeris.

Description

Technical Field

[0001] The present disclosure relates to non-terrestrial networks (NTNs). More specifically, the present disclosure relates to methods and apparatuses for providing neighboring cell information in non-terrestrial networks.

[0002] Certain examples of the present disclosure provide one or more techniques for providing neighboring cell information in a non-terrestrial network (NTN). For example, certain examples of the present disclosure provide one or more techniques for providing neighboring cell information in a 3rd Generation Partnership Project (3GPP) 5th Generation (5G) New Radio (NR) NTN. Background Art

[0003] 5G mobile communication technology defines wide frequency bands, enabling high transmission rates and new services, and can be implemented not only in frequency bands such as "Sub 6 gigahertz (GHz)" like 3.5 GHz, but also in the "Above 6 GHz" frequency bands known as millimeter waves (mmWave) including 28 GHz and 39 GHz. In addition, the implementation of 6th Generation (6G) mobile communication technology (referred to as Beyond 5G systems) in the terahertz (THz) frequency band (e.g., 95 GHz to 3 THz frequency band) is also considered to achieve a transmission rate 50 times faster than 5G mobile communication technology and an ultra-low latency one-tenth of 5G mobile communication technology.

[0004] At the beginning of the development of 5G mobile communication technology, in order to support services and meet the performance requirements related to enhanced mobile broadband (eMBB), ultra-reliable low-latency communication (URLLC), and massive machine-type communication (mMTC), standardization has been carried out on the following items: beamforming and massive multiple-input multiple-output (MIMO) for reducing radio wave path loss and increasing radio wave transmission distance in millimeter waves, parameter sets (e.g., operating multiple subcarrier spacings) for supporting dynamic operations for efficient utilization of millimeter wave resources and time slot formats, initial access technologies for supporting multi-beam transmission and broadband, the definition and operation of bandwidth parts (BWPs), new channel coding methods (such as low-density parity-check (LDPC) codes for large data transmission and polar codes for highly reliable transmission of control information), L2 preprocessing, and network slicing for providing dedicated networks dedicated to specific services.

[0005] Currently, in view of the services to be supported by 5G mobile communication technology, discussions are ongoing regarding improvements and performance enhancements for initial 5G mobile communication, and physical layer standardization has been carried out for the following technologies: For example, vehicle-to-everything (V2X) which is used to assist autonomous vehicles in making driving judgments and improve user convenience based on information about the position and status of vehicles transmitted through vehicles, new radio unlicensed (NR-U) which aims to comply with the requirements related to various regulations in the unlicensed band for system operation, energy saving of NR user equipment (UE), and non-terrestrial network (NTN) which is UE satellite direct communication for providing coverage and positioning in areas where communication with the terrestrial network is not possible.

[0006] In addition, standardization of the air interface architecture / protocol for the following technologies has been ongoing: For example, industrial Internet of Things (IIoT) which supports new services through interoperability and integration with other industries, integrated access and backhaul (IAB) which provides nodes for network service area expansion by supporting wireless backhaul links and access links in an integrated manner, mobility enhancements including conditional handover and dual active protocol stack (DAPS) handover, and two-step random access (two-step random access channel (RACH) for NR) which simplifies the random access process. Standardization of the system architecture / services for the 5G baseline architecture (e.g., service-based architecture or service-based interface) has also been ongoing for combining network function virtualization (NFV) and software-defined network (SDN) technologies, as well as for mobile edge computing (MEC) which receives services based on UE location.

[0007] With the commercialization of the 5G mobile communication system, exponentially growing connected devices will be connected to the communication network, so enhanced functions and performance of 5G mobile communication and integrated operation of connected devices are expected to be necessary. For this purpose, new research related to the following items is planned: extended reality (XR) which effectively supports augmented reality (AR), virtual reality (VR), mixed reality (MR), etc., using artificial intelligence (AI) and machine learning (ML) to improve 5G performance and reduce complexity, AI service support, metaverse service support, and drone communication.

[0008] The above information is provided only as background information to help understand the present disclosure. No decision has been made and no assertion has been made as to whether any of the above applies to the prior art of the present disclosure. Summary of the Invention

[0009] Technical Solution Multiple aspects of the present disclosure will at least solve the above problems and / or disadvantages and will at least provide the advantages described below. Accordingly, one aspect of the present disclosure will provide a method and apparatus for providing adjacent cell information in a non-terrestrial network.

[0010] Additional aspects will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the presented embodiments.

[0011] According to one aspect of the present disclosure, there is provided a method performed by a user equipment (UE) in a wireless communication system. The method includes: receiving, from a base station, a first system information block (SIB) associated with satellite assistance information, the first SIB including first information about a serving cell ephemeris and second information about a valid duration of the serving cell ephemeris; and receiving, from the base station, a second system information block (SIB) associated with adjacent satellite information based on a first timer having a duration that is the valid duration of the serving cell ephemeris and a second timer for obtaining the first SIB before a radio link failure (RLF), the second SIB including third information about an adjacent cell ephemeris.

[0012] According to another aspect of the present disclosure, there is provided a UE in a wireless communication system. The UE includes a transceiver and a controller coupled to the transceiver and configured to: receive, from a base station, a first SIB associated with satellite assistance information, the first SIB including first information about a serving cell ephemeris and second information about a valid duration of the serving cell ephemeris; and receive, from the base station, a second SIB associated with adjacent satellite information based on a first timer having a duration that is the valid duration of the serving cell ephemeris and a second timer for obtaining the first SIB before an RLF, the second SIB including third information about an adjacent cell ephemeris.

[0013] According to another aspect of the present disclosure, there is provided a method performed by a base station in a wireless communication system. The method includes: transmitting, to a UE, a first SIB associated with satellite assistance information, the first SIB including first information about a serving cell ephemeris and second information about a valid duration of the serving cell ephemeris; and transmitting, to the UE, an SIB associated with adjacent satellite information based on a first timer having a duration that is the valid duration of the serving cell ephemeris and a second timer for obtaining the first SIB before an RLF, the second SIB including third information about an adjacent cell ephemeris.

[0014] According to another aspect of the present disclosure, a base station in a wireless communication system is provided. The base station includes a transceiver and a controller, the controller being coupled to the transceiver and configured to: send a first SIB associated with satellite assistance information to a UE, the first SIB including first information about a serving cell ephemeris and second information about a valid duration of the serving cell ephemeris; and send a second SIB associated with adjacent satellite information to the UE based on a first timer whose duration is the valid duration of the serving cell ephemeris and a second timer for obtaining the first SIB before RLF, the second SIB including third information about an adjacent cell ephemeris.

[0015] Other aspects, advantages, and salient features of the present disclosure will become apparent to those skilled in the art from the following detailed description, which discloses various embodiments of the present disclosure in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The above and other aspects, features, and advantages of certain embodiments of the present disclosure will become more apparent from the following description taken in conjunction with the accompanying drawings.

[0017] Figure 1A and Figure 1B illustrates an ephemeris synchronization operation according to various embodiments of the present disclosure, where the system information block (SIB) 31 operates normally in Figure 1A and the user equipment (UE) cannot read the SIB 31 during a subsequently expired T318 and triggers a radio link failure (RLF) in Figure 1B

[0018] Figure 2 illustrates a request and response for an adjacent cell via UE-initiated dedicated signaling according to an embodiment of the present disclosure.

[0019] Figure 3 illustrates a request for an adjacent cell ephemeris provided in a UE assistance information message according to an embodiment of the present disclosure.

[0020] Figure 4 illustrates moving from RRC idle mode to radio resource control (RRC) connected mode to obtain adjacent cell ephemeris information according to an embodiment of the present disclosure.

[0021] Figure 5 illustrates, after an uplink synchronization expiration (T317), using an extended protection timer (T318) to read an SIB containing an adjacent cell ephemeris after reading the SIB 31 according to an embodiment of the present disclosure.

[0022] Figure 6 ​Shows an ephemeris of a non-terrestrial network (NTN) neighboring cell provided on a terrestrial network (TN) cell according to an embodiment of the present disclosure.

[0023] Figure 7A Shows obtaining a broadcast NTN neighboring cell ephemeris according to an embodiment of the present disclosure, Figure 7B Shows an example of indicating a need for an NTN cell ephemeris by dedicated signaling according to an embodiment of the present disclosure.

[0024] Figure 8 Is a block diagram of a network entity that can be used in certain examples of the present disclosure according to an embodiment of the present disclosure.

[0025] Figure 9 Shows the structure of a UE according to an embodiment of the present disclosure.

[0026] Figure 10 Shows the structure of a base station according to an embodiment of the present disclosure.

[0027] Throughout the drawings, it should be noted that the same reference numerals are used to describe the same or similar elements, features, and structures. Detailed Description

[0028] The following description with reference to the drawings is provided to assist in a comprehensive understanding of the various embodiments of the present disclosure defined by the claims and their equivalents. It includes various specific details to assist in the understanding, but these are only regarded as examples. Therefore, those of ordinary skill in the art will recognize that various changes and modifications can be made to the various embodiments described herein without departing from the scope and spirit of the present disclosure. In addition, descriptions of well-known functions and configurations may be omitted for clarity and conciseness.

[0029] The terms and words used in the following description and claims are not limited to their bibliographical meanings, but are used by the inventors only to enable a clear and consistent understanding of the present disclosure. Therefore, it should be clear to those skilled in the art that the following description of the various embodiments of the present disclosure is provided for illustrative purposes only and is not intended to limit the present disclosure defined by the appended claims and their equivalents.

[0030] It should be understood that, unless the context clearly dictates otherwise, the singular forms "a," "an," and "the" include plural referents. Thus, for example, reference to "a component surface" includes reference to one or more such surfaces.

[0031] One of the areas currently being developed in the 3rd Generation Partnership Project (3GPP) 5th Generation (5G) wireless technology is the support for non-terrestrial networks (NTN). NTN is a network in which one or more nodes (e.g., next-generation radio access network (NG-RAN) nodes) are provided by non-terrestrial infrastructure (e.g., satellites or high-altitude platform stations (HAPS)). The advantages of using NTN include: (i) extending coverage to areas where more traditional terrestrial networks have limited or no coverage (such as remote areas), (ii) providing continuous coverage in situations where traditional terrestrial networks cannot operate (e.g., during natural disasters), and (iii) improving overall reliability, resilience, and capacity when used in combination with existing terrestrial networks.

[0032] A satellite network implementing network nodes provides coverage through one or more wireless beams that form a "footprint" on the Earth's surface defining a coverage area or cell. NTN cells can be Earth-moving (i.e., moving over the Earth's surface according to the movement of the satellite, such as in the case of low Earth orbit (LEO) satellites), Earth-fixed (i.e., a fixed area on the Earth's surface, such as in the case of geostationary equatorial orbit (GEO) satellites), or quasi-Earth-fixed (i.e., a fixed area on the Earth's surface but maintained for only a limited time as the satellite passes by).

[0033] IoT NTN is a 3GPP research and work item in Release 17 (RP-202689, RAN#90 December 2020) for providing NTN access to evolved universal terrestrial radio access network (E-UTRAN) IoT devices (e.g., narrowband (NB)-IoT and long-term evolution machine type communication (LTE-M), including enhanced machine type communication (eMTC)). As described in 3GPP RP-202689, IoT operations are crucial for many different industries in remote areas with low / no cellular connectivity. The capabilities of NB-IoT and eMTC are well-suited for many applications, but some applications may require satellite connectivity to provide coverage beyond terrestrial deployments.

[0034] NR NTN is a work item in Release 17 for specifying adaptations to allow NR to operate on NTN (RP-211557, RAN#91-e March 2021).

[0035] After the work items in Release 17, there are work items in Release 18 to enhance NR NTN (RP-220953, RAN#95-e March 2022) and IoT NTN (RP-220979, RAN#95-e March 2022).

[0036] Due to the movement of the satellite in a non-geostationary orbit (e.g., LEO), the cells seen by the UE will move (i.e., earth-moving cells). This causes the UE to frequently switch from one cell to another, and such service handovers will occur continuously. Given this, mobility is one of the key issues for both NR NTN and IoT NTN.

[0037] Abbreviations / Definitions In this disclosure, the following abbreviations / definitions are used.

[0038] 3GPP Third Generation Partnership Project 5G Fifth Generation AMF Access and Mobility Management Function AS Access Stratum CFRA Contention-Free Random Access eMTC Enhanced Machine-Type Communication eNB eNodeB EPC Evolved Packet Core E-UTRAN Evolved Universal Terrestrial Radio Access Network GEO Geostationary Earth Orbit gNB gNodeB HAPS High Altitude Platform Station ID Identification / Identity IE Information Element IMEISV International Mobile Station Equipment Identity and Software Version IoT Internet of Things LEO Low Earth Orbit LTE Long-Term Evolution LTE-M LTE Machine-Type Communication MAC Media Access Control MDT Minimized Drive Test MME Mobility Management Entity NB Narrow Band NG Next Generation NR New Radio NTN Non-Terrestrial Network PCI Physical Cell ID PLMN Public Land Mobile Network ProSe Proximity Based Services RAN Radio Access Network RAT Radio Access Technology RLF Radio Link Failure c-RNTI Cell Radio Network Temporary Identifier RRC Radio Resource Control RRM Radio Resource Management S-GW Serving Gateway SMF Session Management Function SRVCC Single Radio Voice Call Continuity TS Technical Specification UE User Equipment UPF User Plane Function V2X Vehicle-to-Everything X2 / Xn Interface between RAN Nodes Overview of NTN System Information Since NTN has multiple NTN-specific information elements that are only needed when accessing NTN cells, and since the information elements are relatively large, it is agreed that new System Information Blocks (SIBs) are needed.

[0039] In NR NTN, SIB19 contains the information required to access NTN cells, as shown in Table 1 below: [Table 1]

[0040]

[0041]

[0042] In IoT NTN, SIB31 contains the information required to access IoT NTN cells, as shown in Table 2 below: [Table 2]

[0043]

[0044]

[0045] The system information contains the following: Serving cell ephemeris elements. This allows the UE to calculate the satellite positions for Doppler and time pre-compensation. This information may be provided in two formats: PVT format. This describes the (X, Y, Z) position and the velocity vector (vX, vY, vZ).

[0046] Orbit parameters. These describe the orbital motion of the satellite, which is used to infer the satellite position.

[0047] TA common parameters. These provide common timing advance parameters that are introduced to compensate for feeder link delays. The signaling includes the following (occupying a total of 57 bits): Absolute TA common (23 bits).

[0048] Drift of the TA common, which defines how the TA common drifts, i.e., the first derivative of the TA common (19 bits).

[0049] Variation of the TA common, which defines how the TA common changes, i.e., the second derivative of the TA common (15 bits).

[0050] Synchronization validity duration. This is used to define how long the ephemeris and the TA common are valid.

[0051] Epoch time. This defines when the synchronization validity duration should start.

[0052] K-Offset. This is the scheduling offset for the timing relationship in NTN.

[0053] K-Mac. This is the scheduling offset used when the downlink and uplink frame timings are misaligned.

[0054] NR NTN specific information is also included (as part of 3GPP TS 38.331): T-Service (signaled in SIB3 of IoT NTN).

[0055] Reference position and distance threshold. This is used to initiate location-based measurements in RRC idle and RRC connected modes.

[0056] Neighbor cell ephemeris. This is used for idle mode measurements.

[0057] Overview of NTN system information acquisition Due to the movement of the NTN payload (e.g., satellite), the ephemeris information is constantly changing, so it is necessary to ensure that the UE is properly synchronized. Therefore, whenever the UE connects to the eNB, the UE needs to read the system information (e.g., SIB19 or SIB31).

[0058] Figure 1A and Figure 1B illustrates an example of ephemeris synchronization operation according to various embodiments of the present disclosure, where SIB31 works properly in Figure 1A , and in Figure 1B , the UE cannot read SIB31 during the subsequently expiring T318 and triggers RLF.

[0059] Referring to Figure 1A and Figure 1B , in IoT NTN, each time SIB31 is read, a timer (T317) associated with the ephemeris element is started. When T317 expires, the UE is no longer considered synchronized and should re-acquire SIB31 to maintain synchronization.

[0060] In IoT NTN, since IoT UEs (LTE-M and NB-IoT UEs) are not expected to be able to obtain system information in the connected mode, the UE tunes away when reading SIB31 and may not be reachable.

[0061] If an IoT NTN UE cannot read SIB31 within a timer (T318) with a configured duration, the UE performs a radio link failure (RLF), similar to other cases where RLF is performed. This operation can be seen in Figure 1A and Figure 1B .

[0062] In NR NTN, the UE should ensure that it has the latest ephemeris (SIB19 in NR) by reading the SIB in a timely manner through the UE implementation.

[0063] Overview of NTN Ephemeris Format There are three ways to signal the ephemeris in NTN: - PVT format, - Orbital ephemeris elements, and - TLE ephemeris elements (only for discontinuous coverage in IoT NTN).

[0064] - PVT Format The PVT format signals the XYZ position and the velocity vector vXYZ. This can be seen in the following information elements, as shown in Table 3 below: [Table 3]

[0065] The position elements (X, Y, Z respectively) each occupy 26 bits, and the velocity elements (vX, vY, vZ) each occupy 18 bits. They Occupy a total of 132 bits.

[0066] Orbit Ephemeris Format Ephemeris orbit parameters (also known as Keplerian format) provide parameters indicating how celestial bodies move in space, which allows for precise synchronization and prediction of future NTN payload positions.

[0067] Ephemeris orbit elements are signaled through the following elements (a total of 164 bits): Semi - Major Axis (33 bits); Eccentricity (20 bits); Periapsis (28 bits); Longitude (28 bits); Inclination (27 bits); and Anomaly (28 bits).

[0068] TLE Orbit Parameter TLE parameters are based on the Two - Line Element Set (TLE), which is an industry - recognized data format for signaling the movement of celestial bodies. While PVT and orbit ephemeris formats can be used to perform precise synchronization, TLE parameters are mainly used for long - term prediction. For example, TLE parameters allow for precise prediction of satellite passes in the coming days.

[0069] The full set of TLE parameters can occupy more than 50 bytes of data, containing many fields not required in 3GPP. Therefore, a reduced set of TLE parameters can be used instead, such as based on the following (a total of 189 bits): Inclination (21 bits); Argument of perigee (22 bits); Right ascension of the ascending node (22 bits); Mean anomaly (22 bits); Eccentricity (24 bits); Mean motion (34 bits); Signaled by (i) decimal (18 bits) and (ii) exponent (5 bits); and Epoch star (21 bits).

[0070] The purpose of some examples of the present disclosure is to at least partially address, solve, and / or mitigate at least one problem and / or disadvantage associated with the related art, such as at least one problem and / or disadvantage described herein. The purpose of some examples of the present disclosure is to provide at least one advantage over the related art, such as at least one advantage described herein.

[0071] The present disclosure is defined in the independent claims. Advantageous features are defined in the dependent claims. Embodiments or examples disclosed in the specification and / or drawings that fall outside the scope of the claims should be understood as examples that contribute to the understanding of the present disclosure.

[0072] In the specification and claims herein, the words "comprising", "including", and "containing" and variations of these words, such as "comprises" and "includes", mean "including but not limited to" and are not intended (nor do they) exclude other features, elements, components, integers, steps, processes, operations, functions, characteristics, attributes, and / or groups thereof.

[0073] Throughout the specification and claims herein, language of the general form "X for Y" (where Y is some action, process, operation, function, activity, or step and X is some means for performing that action, process, operation, function, activity, or step) includes means X that are specifically (but not necessarily uniquely) adapted, configured, or arranged to perform Y.

[0074] Features, elements, components, integers, steps, processes, operations, functions, characteristics, attributes, and / or groups thereof described or disclosed in connection with a particular aspect, embodiment, example, or claim should be understood to be applicable to any other aspect, embodiment, example, or claim described herein, unless incompatible therewith.

[0075] Those skilled in the art will understand that the techniques described herein can be used in any suitable combination.

[0076] Certain examples of the present disclosure provide one or more techniques for providing neighboring cell information in NTN. For example, certain examples of the present disclosure provide one or more techniques for providing neighboring cell information in 3GPP 5G NR NTN. However, those skilled in the art will understand that the present disclosure is not limited to these examples and can be applied in any suitable system or standard, such as one or more existing and / or future-generation wireless communication systems or standards (including any existing or future versions of the same standard specification), such as 3GPP 5G.

[0077] The functions of the various network entities and other features disclosed herein can be applied to corresponding or equivalent entities or features in the same or any other suitable communication system or standard. Corresponding or equivalent entities or features can be regarded as entities or features that perform the same or similar roles, functions, or purposes in the network. For example, the functions of the NG-RAN nodes (e.g., base stations or gNBs) in the following examples can be applied to any other suitable type of entity that performs RAN functions.

[0078] A specific network entity can be implemented as a network element on dedicated hardware, a software instance running on dedicated hardware, and / or a virtualized function instantiated on a suitable platform (e.g., on a cloud infrastructure).

[0079] Those skilled in the art will understand that the present disclosure is not limited to the specific examples disclosed herein. For example: The technologies disclosed herein are not limited to 3GPP 5G.

[0080] One or more entities in the examples disclosed herein can be replaced by one or more alternative entities that perform equivalent or corresponding functions, processes, or operations.

[0081] One or more messages in the examples disclosed herein can be replaced by one or more alternative messages, signals, or other types of information carriers that convey equivalent or corresponding information.

[0082] One or more other elements or entities can be added to the examples disclosed herein.

[0083] In certain examples, one or more non-essential elements or entities can be omitted.

[0084] The functions, processes, or operations of a specific entity in one example can be divided among two or more independent entities in an alternative example.

[0085] The functions, processes, or operations of two or more separate entities in one example can be performed by a single entity in an alternative example.

[0086] The information carried by a specific message in one example can be carried by two or more separate messages in an alternative example.

[0087] The information carried by two or more separate messages in one example can be carried by a single message in an alternative example.

[0088] In alternative examples, if possible, the order of performing operations and / or the order of sending messages can be modified.

[0089] Certain examples of the present disclosure can be provided in the form of a device / equipment / network entity configured to perform one or more defined network functions and / or their methods. Certain examples of the present disclosure can be provided in the form of a system (e.g., a network or a wireless communication system) including one or more such devices / equipment / network entities and / or their methods.

[0090] Adjacent cell ephemeris signaling In IoT NTN, the following agreements were reached at the 3GPP RAN2#120 meeting: Agreement: 1. RAN2 did not introduce the adjacent cell ephemeris in Rel-17 IoT-NTN, neither for eMTC nor for NB-IoT. RAN2 agreed to support this in Rel-18 and provide a detailed FFS.

[0091] In LTE IoT, contrary to NR, the minimum maximum transport block size (TBS) for Release 13 LTE-M and NB-IoT is 1000 and 680 bits respectively, and with appropriate headers (e.g., MAC, radio link control (RLC), packet data convergence protocol (PDCP), and RRC headers), the RRC payload is even smaller. However, depending on the network implementation and deployment, a single ephemeris element may require more than 120 bits, up to more than 200 bits. Therefore, there may be a limit on the number of blocks of adjacent cell ephemeris information that can be signaled.

[0092] Since IoT devices are generally less capable devices in terms of radio sensitivity, number of receive antennas, and worse processing capabilities, introducing more bits in the system information may degrade network performance.

[0093] Access and mobility in NTN rely on the ephemeris and NTN configuration. For the idle mode, it is used to adjust the synchronization signal block (SSB)-measurement timing configuration (SMTC), and also to enable NTN-specific idle mode cell selection and reselection. In NTN, these configurations are broadcast in SIB19 (NR NTN) / SIB31 (IoT NTN).

[0094] If the UE is in the idle mode and camped on an NTN, and needs to measure an adjacent cell that is a non-terrestrial cell, it is not clear how the UE will obtain the required information elements since SIB31 is NTN-specific.

[0095] Certain examples of the present disclosure provide various techniques for providing adjacent cell ephemeris information that mitigate these problems.

[0096] Those skilled in the art will understand that the various techniques disclosed herein are applicable not only to ephemeris information but also to any other suitable type of information.

[0097] Those skilled in the art will understand that the various techniques disclosed herein are applicable not only to satellite payloads but can also be applied to other platforms such as HAPS. Thus, the reference to "satellite ephemeris" can include references not only to satellites but also to other NTN platforms or payloads.

[0098] Those skilled in the art will understand that the various techniques disclosed herein are applicable not only to the "serving" cell and the "neighboring" cell, but also to any other suitable type of cell, which may be referred to as the "first" and "second" cells, respectively.

[0099] Those skilled in the art will understand that the various techniques disclosed herein can be applied to gNB, NG-RAN scenarios and all relevant RRC signaling and / or messages, as well as X2, Xn, S1, NG, F1 signaling and messages, and / or relevant network entities (e.g., MME, AMF, others).

[0100] Those skilled in the art will understand that the various techniques disclosed herein can be applied to IoT NTN and / or NR NTN.

[0101] Various techniques for signaling neighboring cell ephemeris information will now be described.

[0102] In some examples, compared to the serving cell ephemeris, the network can signal the neighboring cell ephemeris with a lower accuracy (e.g., precision, granularity, and / or rough value, e.g., the size / content of an information element represented in bits).

[0103] Given that this information may not be used for cell synchronization but for cell measurements that typically require a lower accuracy of cell information, signaling the neighboring cell ephemeris with a lower granularity / precision can be acceptable.

[0104] In some examples, the precision can be configurable, for example, by having multiple information elements representing the ephemeris, which are then selected by the network according to the purpose. For example, the precision can depend on the NTN deployment, and in cases where the satellite moves relatively slowly, the need for precision related to satellite speed is less. Examples of such signaling scenarios are further disclosed in Example 1 below.

[0105] In some examples, the precision (e.g., lower precision) can be configured by one or more specific parameters. For example, the precision parameter can signal the number of bits for each parameter, or the reduction in the number of bits used to signal a parameter compared to existing ephemeris parameters.

[0106] In some examples, certain neighboring cell ephemeris information (e.g., not all) can be provided with a reduced information precision / resolution / granularity. In such cases, certain other neighboring cell ephemeris information can be provided with full precision / resolution / granularity.

[0107] In some examples, the network may require the adjacent cell ephemeris to be provided in a specific form (e.g., a single more efficient type). For example, the network may require the use of a PVT ephemeris format (which uses relatively fewer bits) or any other suitable relatively low-precision format to signal the adjacent cell ephemeris.

[0108] In some examples, a common TA (which can be considered part of the ephemeris) may reduce its precision in the adjacent cell ephemeris. This can be done independently or in conjunction with a reduction in the precision of other adjacent cell ephemeris information (e.g., signaling of satellite positions). In various examples, the precision of the adjacent cell ephemeris (e.g., PVT, Kepler format, etc.) may be reduced without reducing the precision of the common TA, or the precision of both the common TA and the ephemeris may be reduced.

[0109] In some examples, the adjacent cell ephemeris may be signaled only partially at each system information occasion. For example, if the adjacent cell ephemeris is signaled in SIB31, it may be signaled only in certain SIB31 occasions.

[0110] In some examples, the network may use more than one SIB, e.g., in existing and / or newly defined SIBs, to provide the content (or part) of the adjacent cell information. For example, the content of the adjacent cell ephemeris may be split into different SIBs (existing and / or newly defined). The network may indicate to the UE where to find the different content of the adjacent cell ephemeris, i.e., in which SIBs.

[0111] In some examples, the network may indicate which content (or part) of the adjacent cell information is provided to the UE, e.g., via system information broadcast (e.g., periodically or on demand) and / or dedicated signaling.

[0112] In some examples, the network may provide the UE with information about the availability and / or scheduling of the adjacent cell ephemeris. For example, this information may be provided via system information or dedicated signaling. For example, this information may include information about the mapping of the adjacent cell ephemeris to new and / or existing SIBs. For example, this information may include information about the periodicity, broadcast type (e.g., on demand, periodic), size, resolution / precision / granularity of the adjacent cell ephemeris.

[0113] In some examples, after a request from a UE (e.g., a UE in RRC_IDLE, RRC_INACTIVE, or RRC_CONNECTED), an entire neighboring cell ephemeris may be provided to the UE on demand via broadcast, or only a part of the neighboring cell ephemeris (e.g., a part provided / represented with lower accuracy or granularity). In some examples, after an on-demand request, an entire neighboring cell ephemeris or a part thereof may be provided to the UE, e.g., via system information broadcast (periodically, on demand) and / or dedicated signaling.

[0114] In some examples, the neighboring cell ephemeris may be provided only via dedicated signaling and not broadcast. This may be advantageous in some cases because if the UE is connected only for a very limited time and the neighboring cell ephemeris may cause broadcast coverage problems, the neighboring cell ephemeris may not be needed. In such cases, the UE may signal the need for the neighboring cell ephemeris after connection. For example, the UE may signal in response to the UE having a relatively large amount of data in its buffer. Figure 2 An example of such signaling is shown.

[0115] Figure 2 A neighboring cell request and response via UE-initiated dedicated signaling according to an embodiment of the present disclosure is shown.

[0116] Figure 3 A neighboring cell ephemeris request provided in a UE assistance information message according to an embodiment of the present disclosure is shown.

[0117] Reference Figure 2 and Figure 3 , in operation 1, the UE may determine whether an NTN neighboring cell ephemeris is needed, whether full information accuracy or reduced accuracy ephemeris is needed, and / or whether a full ephemeris or only a part of the ephemeris is needed based on any suitable set of one or more criteria, where any suitable set of the one or more criteria may include, for example, one or more of the following: The amount of data in the buffer is higher than a given / predefined threshold. For example, in operation 2, this may mean that the UE will remain in the connected mode long enough in case neighboring cell measurements are needed.

[0118] The serving cell signal strength is lower than a given / predefined threshold. For example, this may mean that mobility may be needed soon, and thus information for performing mobility may be needed.

[0119] The neighboring cell is served by a different satellite. For example, in operation 2, this may indicate that the serving cell ephemeris is different from the neighboring cell ephemeris, in which case the neighboring cell ephemeris may not be derivable / inferable from the serving cell ephemeris.

[0120] In some examples, the indication of the NTN neighbour cell ephemeris may be included in any suitable message, such as one or more of the following messages: In any RRC–Complete message (sometimes referred to as Msg5): RRCConnectionSetupComplete; RRCConnectionResumeComplete; RRCConnectionReconfigurationComplete; and RRCConnectionReestablishmentComplete.

[0121] The network may indicate that the above should be provided / indicated. For example, this may be necessary if some eNBs have not yet implemented a method for sending neighbour cell measurements while some eNBs have implemented the method (in which case in some situations it may not be necessary to send the above indication). For example, an indication that the above should be indicated may be sent in broadcast manner, such as SIB1 or SIB2.

[0122] In the UE assistance information message; The RRC message is UEAssistanceInformation (see Figure 2 ).

[0123] Measurement Report Whenever a measurement report is triggered due to RRC measurements, the UE may indicate the need for the neighbour cell ephemeris, for example, in a flag.

[0124] The RRC message is MeasurementReport This can be configured in a reporting configuration (e.g., ReportConfigEUTRA) by a flag that indicates that the need for the neighbour cell ephemeris should be indicated in the measurement report.

[0125] In the MAC CE In some examples, the request and response for the neighbour cell ephemeris may be completed in a new RRC message, such as a neighbour cell ephemeris request / response message, or in one or more newly defined IEs, such as NeighbourCellEphemerisRequest / NeighbourCellEphemerisResponse.

[0126] In some examples, the UE may provide an indication of the required / desired information (e.g., an indication of which part of the neighboring cell ephemeris is needed) in a request for the neighboring cell ephemeris, or the expected / desired granularity, etc.

[0127] In some examples, in operation 3, if the only way to transfer / obtain the neighboring cell ephemeris is through dedicated signaling, the UE may move from RRC idle mode to RRC connected mode to obtain neighboring cell information if the UE needs the neighboring cell ephemeris for RRC idle mode operation. In some examples, the UE may indicate the reason for connecting to the eNB, particularly to obtain the NTN neighboring cell ephemeris (e.g., establishmentCause, resumeCause, re - establishmentCause). Figure 4 An example of the process is shown.

[0128] Figure 4 Shows moving from Radio Resource Control (RRC) idle mode to RRC connected mode to obtain neighboring cell ephemeris information according to an embodiment of the present disclosure.

[0129] Refer to Figure 4 , in some examples, if the neighboring cell ephemeris is broadcast, to read this broadcast information, the UE may transition from RRC_CONNECTED or RRC_IDLE. For example, this can be done by the UE signaling in operation 1 that it wants to enter RRC_IDLE due to the need to obtain the neighboring cell ephemeris. For example, this can be done using the Access Stratum Release Assistance Indication (AS RAI), or by using ReleasePreference and further indicating that the AS RAI or ReleasePreference is due to the need to read the neighboring cell ephemeris.

[0130] In some examples, if the neighboring cell ephemeris is the same as the serving cell ephemeris, the network may signal this situation using a flag, for example. In this case, this can avoid signaling the neighboring cell ephemeris. In some examples, for each neighboring cell, the network may signal only certain information, such as the required PCI, frequency, etc. This may allow for a backward - compatible implementation. See Example 2 below.

[0131] In some examples, if the NTN network wants the UE to monitor neighboring TN cells, the network may signal that it is a TN cell. For example, this can be implicitly achieved by not including the ephemeris element, or explicitly by using a flag.

[0132] In some examples, the UE may indicate its ability to read the ephemeris of adjacent cells. For example, this may be a specific type of format that the UE is capable of reading with lower resolution / accuracy / granularity.

[0133] Newly defined SIB for the ephemeris of adjacent cells In some examples, the ephemeris of adjacent cells may be provided in the newly defined SIB.

[0134] In this case, there may be requirements for: when to read the new SIB, and the requirements and operations for reading the current NTN system information (such as SIB31).

[0135] In some examples, the UE may be configured to read the new ephemeris SIB of adjacent cells according to one or more of the following: Whenever a UE with NTN capability reads SIB31, or operates directly after reading SIB31. This can provide the advantage that the operations when reading SIB31 can be replicated. This also requires the network to broadcast the new ephemeris SIB of adjacent cells directly after SIB31. Such examples are disclosed in Example 3 below.

[0136] To address the problem of extended system information reading time, a longer time T318 may be configured for this specific case. Figure 5 Such examples are shown in

[0137] Figure 5 Shows reading the SIB containing the ephemeris of adjacent cells after reading SIB31, using an extended protection timer (T318) after the expiration of uplink synchronization (T317), according to an embodiment of the present disclosure.

[0138] Figure 6 Shows providing the NTN ephemeris of adjacent cells on a terrestrial network (TN) cell, according to an embodiment of the present disclosure.

[0139] Reference Figure 5 and Figure 6 , reading the new ephemeris SIB of adjacent cells may not require its own T317 (uplink synchronization - ul-SyncValidityTimer) timer.

[0140] In some examples, in Figure 4 operation 3 of, if it is detected that the new SIB has changed, the UE may obtain the new ephemeris SIB of adjacent cells whenever SIB31 is obtained.

[0141] In some cases, when the NTN UE reads SIB31, for example: When reading SIB31 when transitioning from the idle mode to the connected mode.

[0142] When re - establishing a connection to an NTN cell.

[0143] When certain conditions are met: The amount of data in the UE's buffer exceeds a certain quantity.

[0144] The UE is able to monitor neighboring cells in RRC connected mode.

[0145] In some examples, the UE may be able to monitor neighboring cells in RRC idle mode using NTN neighbor cell assistance information.

[0146] In some examples, the UE may be allowed to request new SIBs on - demand.

[0147] NTN neighbor cell information signaled in the terrestrial network In NR NTN and IoT NTN, idle and connected mode mobility between the terrestrial network and the non - terrestrial network is supported.

[0148] In some examples, the network may signal the required non - terrestrial information in the terrestrial network. This allows the UE to perform measurements on the non - terrestrial network while being located on the terrestrial network.

[0149] In some examples, to signal the above, the network may broadcast NTN SIBs (e.g., SIB19 for NR NTN and SIB31 for IoT NTN) in the terrestrial network. To indicate that the terrestrial network is not NTN, a flag may be included in the system information.

[0150] In some examples, NTN neighbor cell information may be passed to the UE in a dedicated manner. For example, this may be achieved through dedicated system information transmission of SIB19 or SIB31, or in any other suitable way, such as a separate information element with neighbor cell information, which may be sent in a separate message or as part of the RRC configuration.

[0151] Figure 7A Illustrates obtaining a broadcast NTN neighbor cell ephemeris according to an embodiment of the present disclosure, Figure 7B Illustrates indicating the need for an NTN cell ephemeris through dedicated signaling according to an embodiment of the present disclosure.

[0152] Reference Figure 7A and Figure 7B , for (i) obtaining NTN system information in the broadcast terrestrial network, or (ii) if provided through dedicated signaling, the UE may be configured to (a) obtain NTN system information in SIB19 or SIB31 (see Figure 7A), or (b) indicates that the UE needs a dedicated NTN neighbor cell ephemeris (see Figure 7B ). In some examples, the condition for any of the above may be one or more of the following: The UE has NTN capabilities.

[0153] The network indicates that it is required, for example, via a configuration flag.

[0154] The UE has poor coverage.

[0155] There is a radio link failure.

[0156] If the relevant SIB exists in the terrestrial network.

[0157] In some examples, in operation 1, it may be determined whether to obtain NTN system information according to the UE implementation and / or usage, such as one or more of the following: If the UE is expected to operate in an environment where mobility to NTN is required.

[0158] Use the history of connections to NTN.

[0159] The serving cell ephemeris usually exists in NTN (it is optionally present in SIB19 and mandatorily present in SIB31). Some examples of the present disclosure address this issue: When signaling the NTN SIB in the terrestrial network, the network does not signal the serving cell ephemeris. Since the serving cell ephemeris in SIB19 is optional, this can be done for NR NTN.

[0160] Ignore the serving cell ephemeris. Since the serving cell ephemeris is mandatorily present, this can be done for IoT NTN. For example, it can be ignored based on the configuration of a flag indicating to the UE that it should be ignored. In some examples, the signaled ephemeris value can implicitly indicate this. For example, the PVT ephemeris value can be (x = 0, y = 0, z = 0, vx = 0, vy = 0, vz = 0).

[0161] In this case, some serving cell ephemeris fields may be default not signaled, such as TA common parameters, epoch time, k-Mac, etc.

[0162] If the serving cell ephemeris is signaled in the terrestrial network, it can be reused to indicate the neighbor NTN cell ephemeris.

[0163] In some examples, in operation 2, the UE can indicate its ability to obtain the NTN neighbor cell ephemeris to the terrestrial network, or the non-terrestrial network, or both.

[0164] Example Example 1 According to an embodiment of the present disclosure, the embodiment regarding Example 1 can be described as shown in Table 4 below.

[0165] [Table 4]

[0166]

[0167]

[0168]

[0169]

[0170] Example 2 In this example, the network signals that the ephemeris of the neighboring cell is the same as that of the serving cell.

[0171] According to an embodiment of the present disclosure, the embodiment regarding Example 2 can be described as shown in Table 5 below.

[0172] [Table 5]

[0173]

[0174]

[0175]

[0176] Example 3 In this case, in Operation 2, if the UE can perform NTN neighboring cell measurements using the NTN ephemeris and if the UE can perform NTN neighboring cell measurements using the NTN neighboring cell ephemeris in the RRC connected mode, then the UE obtains the neighboring cell ephemeris in the RRC idle mode. The UE also directly reads the new SIB after SBI31. In Operation 3, the TN eNB sends the NTN neighboring cell ephemeris to the UE.

[0177] According to an embodiment of the present disclosure, the embodiment regarding Example 3 can be described as shown in Table 6 below.

[0178] [Table 6]

[0179]

[0180]

[0181] Example 4 In this example, the T318 timer is extended for a UE attempting to obtain a new SIB containing the ephemeris of an adjacent cell.

[0182] According to an embodiment of the present disclosure, the embodiment regarding Example 4 can be described as shown in Table 7 below.

[0183] [Table 7]

[0184]

[0185]

[0186]

[0187]

[0188]

[0189]

[0190] Figure 8 is a block diagram of a network entity that can be used in an example of the present disclosure.

[0191] Referring to Figure 8 , for example, Figure 1A 、 Figure 1B 、 Figures 2 to 6 、 Figure 7A and Figure 7B the UE and / or gNB in the examples of Figure 8 can include the entities of

[0192] Entity 800 includes a processor (or controller) 801, a transmitter 803, and a receiver 805. The receiver 805 is configured to receive one or more messages from one or more other network entities, as described above. The transmitter 803 is configured to send one or more messages to one or more other network entities, as described above. The processor 801 is configured to perform one or more operations, for example, according to the operations described above.

[0193] The techniques described herein can be implemented using any suitably configured apparatus and / or system. Such an apparatus and / or system can be configured to perform a method according to any aspect, embodiment, example, or claim disclosed herein. Such an apparatus can include one or more elements, such as one or more of a receiver, transmitter, transceiver, processor, controller, module, unit, etc., each element being configured to perform one or more corresponding processes, operations, and / or method steps for implementing the techniques described herein. For example, the operation / function of X can be performed by a module (or X module) configured to perform X. One or more elements can be implemented in the form of hardware, software, or any combination of hardware and software.

[0194] It should be understood that examples of the present disclosure can be implemented in the form of hardware, software, or any combination of hardware and software. Any such software can be stored in the form of volatile or non-volatile memory, such as a storage device like a read-only memory (ROM), whether erasable or rewritable, or in the form of a memory such as a random access memory (RAM), a memory chip, device, or integrated circuit, or stored on an optically or magnetically readable medium, such as a compact disc (CD), a digital versatile disc (DVD), a disk, or a magnetic tape, etc.

[0195] It should be understood that storage devices and storage media are examples of machine-readable memories suitable for storing one or more programs, which include instructions that, when executed, implement certain examples of the present disclosure. Thus, certain examples provide a program that includes code for implementing a method, apparatus, or system according to any example, embodiment, aspect, and / or claim disclosed herein, and / or a machine-readable memory storing such a program. Additionally, such a program can be transmitted electronically via any medium, such as a communication signal carried via a wired or wireless connection.

[0196] Certain examples of the present disclosure provide a method for a user equipment (UE) to obtain second cell information (e.g., ephemeris information) of a second cell (e.g., an adjacent cell), where the second cell is a non-terrestrial network (NTN) cell. The method includes: in response to the expiration of a first timer (e.g., T317), indicating that the validity of first cell information (e.g., ephemeris information) of a first cell (e.g., a serving cell) has expired, starting a second timer (e.g., T318), and attempting to obtain the second cell information during the second timer period.

[0197] In certain examples, when attempting to obtain the second cell information during the second timer period, a longer time can be configured for the second timer compared to the case where the second cell information is not attempted to be obtained during the second timer period.

[0198] In some examples, the method may further include: attempting to obtain first cell information during a second timer period.

[0199] In some examples, it is possible to (i) attempt to obtain second cell information while attempting to obtain first cell information, or (ii) attempt to obtain second cell information after having obtained first cell information.

[0200] In some examples, the second cell information may be included in system information (e.g., SIB31) different from the system information that includes the first cell information (e.g., system information block (SIBxx)).

[0201] In some examples, the method may further include: the network directly broadcasting the second cell information (e.g., SIBxx) after the first cell information (e.g., SIB31).

[0202] In some examples, the UE may be in a connected mode (e.g., radio resource control (RRC) connected mode).

[0203] In some examples, the method may further include: determining one or more of the following: whether the UE is capable of obtaining the second cell information, and whether the UE has NTN capabilities.

[0204] In some examples, the first cell may be an NTN cell or a terrestrial network (TN) cell.

[0205] Certain examples of the present disclosure provide a base station configured to perform the method according to any example, aspect, embodiment, and / or claim disclosed herein.

[0206] Certain examples of the present disclosure provide a network (or wireless communication system) including a base station and a UE according to any example, aspect, embodiment, and / or claim disclosed herein.

[0207] Certain examples of the present disclosure provide a computer program including instructions that, when executed by a computer or a processor, cause the computer or the processor to perform the method according to any example, aspect, embodiment, and / or claim disclosed herein.

[0208] Certain examples of the present disclosure provide a computer or processor-readable data carrier having stored thereon a computer program according to any example, aspect, embodiment, and / or claim disclosed herein.

[0209] Certain examples of the present disclosure provide one or more methods, base stations, networks, computer programs, and / or computer or processor-readable data carriers according to one or more of the following aspects.

[0210] According to a first aspect, there is provided a method for a first cell (e.g., serving cell) to provide cell information (e.g., ephemeris information) of a second cell (e.g., neighboring cell), where the second cell is a non-terrestrial network (NTN) cell. The method includes: sending the cell information of the second cell to a UE in the first cell, where, compared with sending the cell information of the first cell to the UE, (i) fewer bits are used, (ii) a lower frequency is used, and / or (iii) the sending is performed in multiple parts.

[0211] According to a second aspect, there is provided a method according to the first aspect, where sending the cell information of the second cell using fewer bits includes: sending at least a first part (e.g., common TA) of the cell information of the second cell using fewer bits than the corresponding part of the cell information of the first cell.

[0212] According to a third aspect, there is provided a method according to the second aspect, where sending the cell information of the second cell using fewer bits includes: sending a second part of the cell information of the second cell using the same number or more bits compared with the corresponding part of the cell information of the first cell.

[0213] According to a fourth aspect, there is provided a method according to the first aspect, the second aspect or the third aspect, where sending the cell information of the second cell using fewer bits includes: sending at least a part of the cell information of the second cell with a lower accuracy (e.g., lower precision, lower granularity, higher roughness) than the cell information of the first cell.

[0214] According to a fifth aspect, there is provided a method according to any of the foregoing aspects, where sending the cell information of the second cell using fewer bits includes: sending only a part of the cell information of the second cell.

[0215] According to a sixth aspect, there is provided a method according to any of the foregoing aspects, where sending the cell information of the second cell using fewer bits includes: using a format (e.g., PVT format) and / or coding different from the format and / or coding used for sending the cell information of the first cell to send at least a part of the cell information of the second cell.

[0216] According to a seventh aspect, there is provided a method according to any of the foregoing aspects, where each part of the cell information of the second cell is sent in respective information elements (IEs).

[0217] According to an eighth aspect, there is provided a method according to any of the foregoing aspects, where the cell information of the second cell is sent based on a network configuration (e.g., defining the total number of bits for sending information and / or the number of bits for each parameter defining the information).

[0218] According to a ninth aspect, there is provided a method according to any of the foregoing aspects, wherein transmitting cell information of a second cell at a lower frequency includes: transmitting at least a part of the cell information of the second cell only in some scheduled transmissions (e.g., SIB transmission / SIB occasion).

[0219] According to a tenth aspect, there is provided a method according to any of the foregoing aspects, wherein transmitting cell information of a second cell using more parts includes: transmitting a first part of the cell information of the second cell in a first system information block (SIB) (e.g., SIB31), and transmitting a second part of the cell information of the second cell in a second SIB (e.g., an SIB other than SIB31).

[0220] According to an eleventh aspect, there is provided a method according to the tenth aspect, wherein the method further includes: obtaining, by a UE (e.g., through system information, broadcast, dedicated signaling, and / or in response to a request), information defining one or more of the following: the identity of the SIBs including the first and second parts of the cell information of the second cell, the availability of the first SIB and the second SIB, and the scheduling of the first SIB and the second SIB.

[0221] According to a twelfth aspect, there is provided a method according to any of the foregoing aspects, wherein transmitting cell information of a second cell is based on one or more of the following: periodically, in response to a request (e.g., from a UE), through system information, through broadcast transmission, through dedicated signaling.

[0222] According to a thirteenth aspect, there is provided a method according to any of the foregoing aspects, the method further including: receiving an indication of a cell (e.g., a second cell) from a UE, and in response to the indication, transmitting the cell information of the indicated cell.

[0223] According to a fourteenth aspect, there is provided a method according to the thirteenth aspect, the method further including: determining, by a UE, a cell for which cell information is required based on one or more specific criteria.

[0224] According to a fifteenth aspect, there is provided a method according to the fourteenth aspect, wherein the one or more criteria are based on one or more of the following: the amount of data in the buffer of the UE (e.g., whether the amount of data in the buffer exceeds a specific threshold), the signal strength of a first cell (e.g., whether the signal strength of the first cell measured by the UE is below a specific threshold), which satellite serves the second cell (e.g., whether the second cell is served by a satellite different from the first cell).

[0225] According to a sixteenth aspect, there is provided a method according to any of the foregoing aspects, wherein the first cell is an NTN cell or a terrestrial network (TN) cell.

[0226] According to a seventeenth aspect, a base station is provided, which is configured to execute the method according to any of the foregoing aspects.

[0227] According to an eighteenth aspect, a network (or wireless communication system) is provided, which includes a UE and a base station according to the seventeenth aspect.

[0228] According to a nineteenth aspect, a computer program including instructions is provided, which, when executed by a computer or a processor, causes the computer or the processor to execute the method according to any of the first to sixteenth aspects.

[0229] According to a twentieth aspect, a computer or processor-readable data carrier is provided, on which the computer program according to the nineteenth aspect is stored.

[0230] According to an embodiment of the present disclosure, a method for a user equipment (UE) to obtain second cell information (e.g., ephemeris information) of a second cell (e.g., an adjacent cell), where the second cell is a non-terrestrial network (NTN) cell, the method includes: in response to the expiration of a first timer (e.g., T317), indicating that the validity of the first cell information (e.g., ephemeris information) of a first cell (e.g., a serving cell) has expired, starting a second timer (e.g., T318), and attempting to obtain the second cell information during the second timer period.

[0231] According to an embodiment of the present disclosure, when attempting to obtain the second cell information during the second timer period, a longer time is configured for the second timer compared to the case where the second cell information is not attempted to be obtained during the second timer period.

[0232] According to an embodiment of the present disclosure, it further includes: attempting to obtain the first cell information during the second timer period.

[0233] According to an embodiment of the present disclosure, (i) attempt to obtain the second cell information while attempting to obtain the first cell information, or (ii) attempt to obtain the second cell information after the first cell information has been obtained.

[0234] According to an embodiment of the present disclosure, the second cell information is included in system information (e.g., SIBxx) different from the system information (e.g., SIB31) including the first cell information.

[0235] According to an embodiment of the present disclosure, it further includes: the network directly broadcasts the second cell information (e.g., SIBxx) after the first cell information (e.g., SIB31).

[0236] According to an embodiment of the present disclosure, the UE is in a connected mode (e.g., a radio resource control (RRC) connected mode).

[0237] According to an embodiment of the present disclosure, it further includes: determining whether the UE can obtain second cell information and whether the UE has NTN capabilities, one or more of them.

[0238] According to an embodiment of the present disclosure, the first cell is an NTN cell or a terrestrial network (TN) cell.

[0239] According to an embodiment of the present disclosure, the base station is configured to perform the above operations.

[0240] According to an embodiment of the present disclosure, a network (or a wireless communication system) includes a UE and a base station that performs the above operations.

[0241] According to an embodiment of the present disclosure, a computer program is provided, which includes instructions that, when the program is executed by a computer or a processor, cause the computer or the processor to perform the above operations.

[0242] According to an embodiment of the present disclosure, a computer or processor-readable data carrier is provided, on which a computer program is stored. The computer program includes instructions that, when the program is executed by a computer or a processor, cause the computer or the processor to perform the above operations.

[0243] Figure 9 The structure of a UE according to an embodiment of the present disclosure is shown.

[0244] Referring to Figure 9 , according to an embodiment of the present disclosure, the UE may include a transceiver 910, a memory 920, and a processor 930. The transceiver 910, memory 920, and processor 930 of the UE may operate according to the above communication method of the UE. However, the components of the UE are not limited thereto. For example, the UE may include more or fewer components than those described above. In addition, the processor 930, transceiver 910, and memory 920 may be implemented as a single chip. In addition, the processor 930 may include at least one processor.

[0245] The transceiver 910 is collectively referred to as a UE receiver and a UE transmitter, and may send signals to or receive signals from a base station or a network entity. The signals sent to or received from a base station or a network entity may include control information and data. The transceiver 910 may include a radio frequency (RF) transmitter for upconverting and amplifying the frequency of the transmitted signal, and an RF receiver for amplifying low noise and downconverting the frequency of the received signal. However, this is only an example of the transceiver 910, and the components of the transceiver 910 are not limited to the RF transmitter and the RF receiver.

[0246] In addition, the transceiver 910 may receive signals through a wireless channel and output them to the processor 930, and send the signals output from the processor 930 through the wireless channel.

[0247] The memory 920 may store programs and data required for the operation of the UE. In addition, the memory 920 may store control information or data included in the signals obtained by the UE. The memory 920 may be a storage medium such as a read-only memory (ROM), a random access memory (RAM), a hard disk, a CD-ROM, and a DVD, or a combination of storage media.

[0248] The processor 930 may control a series of processes such that the UE operates as described above. For example, the transceiver 310 may receive a data signal including a control signal sent by a base station or a network entity, and the processor 930 may determine the result of receiving the control signal and the data signal sent by the base station or the network entity.

[0249] Figure 10 The structure of a base station according to an embodiment of the present disclosure is shown.

[0250] Reference Figure 10 , a base station according to an embodiment may include a transceiver 1010, a memory 1020, and a processor 1030. The transceiver 1010, the memory 1020, and the processor 1030 of the base station may operate according to the communication method of the base station described above. However, the components of the base station are not limited thereto. For example, the base station may include more or fewer components than those described above. In addition, the processor 1030, the transceiver 1010, and the memory 1020 may be implemented as a single chip. In addition, the processor 1030 may include at least one processor.

[0251] The transceiver 1010 is collectively referred to as a base station receiver and a base station transmitter, and may send / receive signals to / from a terminal (UE) or a network entity. The signals sent to or received from the terminal or the network entity may include control information and data. The transceiver 1010 may include an RF transmitter for up-converting and amplifying the frequency of the transmitted signal, and an RF receiver for amplifying low noise and down-converting the frequency of the received signal. However, this is only an example of the transceiver 1010, and the components of the transceiver 1010 are not limited to the RF transmitter and the RF receiver.

[0252] In addition, the transceiver 1010 may receive a signal through a wireless channel and output it to the processor 1030, and send a signal output from the processor 1030 through the wireless channel.

[0253] The memory 1020 may store programs and data required for the operation of the base station. In addition, the memory 1020 may store control information or data included in the signals obtained by the base station. The memory 1020 may be a storage medium such as a read-only memory (ROM), a random access memory (RAM), a hard disk, a CD-ROM, and a DVD, or a combination of storage media.

[0254] The processor 1030 may control a series of processes such that the base station operates as described above. For example, the transceiver 1010 may receive a data signal including a control signal sent by a terminal, and the processor 1030 may determine the result of receiving the control signal and the data signal sent by the terminal.

[0255] It should also be understood that the “at least one / at least a” described in the present disclosure includes any and / or all possible combinations of the listed items, and the various embodiments and various examples in the embodiments described in the present disclosure may be changed and combined in any suitable form, and the “ / ” described in the present disclosure means “and / or”.

[0256] The illustrative logic blocks, modules, and circuits described in the present disclosure may be implemented in a general-purpose processor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field-programmable gate array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof to perform the functions described herein. The general-purpose processor may be a microprocessor, but in an alternative, the processor may be any processor, controller, microcontroller, or state machine in the related art. The processor may also be implemented as a combination of computing devices, such as a combination of a DSP and a microprocessor, multiple microprocessors, one or more microprocessors cooperating with a DSP core, or any other such configuration.

[0257] The steps of the methods or algorithms described in the present disclosure may be directly embodied in hardware, in a software module executed by a processor, or in a combination of both. The software module may reside in a RAM memory, a flash memory, a ROM memory, an erasable programmable ROM (EPROM) memory, an electrically EPROM (EEPROM) memory, a register, a hard disk, a removable disk, or any other form of storage medium known in the art. The storage medium is connected to the processor such that the processor can read information from, or write information to, the storage medium. In an alternative, the storage medium may be integrated into the processor. The processor and the storage medium may reside in an ASIC. The ASIC may reside in a user terminal. In an alternative, the processor and the storage medium may reside as separate components in the user terminal.

[0258] In one or more designs, the described functions may be implemented in hardware, software, firmware, or any combination thereof. If implemented in software, each function may be stored on or transmitted by a computer-readable medium as one or more instructions or code. The computer-readable medium includes computer storage media and communication media, the latter including any medium that facilitates the transfer of a computer program from one place to another. The storage media may be any available media accessible by a general-purpose or special-purpose computer.

[0259] The descriptions set forth herein in connection with the accompanying drawings describe example configurations, methods, and devices and do not represent all examples that may be implemented or that are within the scope of the claims. As used herein, the term "example" means "serving as an example, instance, or illustration" and not "preferred" or "superior to other examples." The detailed description includes specific details to provide an understanding of the described technology. However, the technology may be practiced without these specific details. In some instances, well-known structures and devices are shown in block diagram form to avoid obscuring the concepts of the described examples.

[0260] Although this specification contains many specific implementation details, these details should not be construed as limitations on the scope of what is claimed but rather as descriptions of features specific to particular embodiments of the present disclosure. Some features that are described in the context of separate embodiments in this specification may also be combined in a single embodiment. Conversely, the various features that are described in the context of a single embodiment may also be implemented separately in multiple embodiments or in any suitable sub-combination. Additionally, although a feature may be described as acting in certain combinations and even initially claimed as such, in some cases, one or more features from a claimed combination may be deleted from the combination, and the claimed combination may be directed to a sub-combination or a variant of a sub-combination.

[0261] It should be understood that the specific order or hierarchy of steps in the methods of the present disclosure is an illustration of a process. Based on design preferences, it is understood that the specific order or hierarchy of steps in the method may be rearranged to achieve the functions and effects disclosed in the present disclosure. The appended method claims present the elements of the various steps in an example order and are not meant to be limited to the specific order or hierarchy presented unless specifically stated otherwise. Additionally, although an element may be described or claimed in the singular form, the plural form may also be contemplated unless expressly stated to be limited to the singular form. Accordingly, the present disclosure is not limited to the examples shown, and any means for performing the functions described herein are included in the various aspects of the present disclosure.

[0262] The text and the drawings are provided only as examples to assist the reader in understanding the present disclosure. They are not intended nor should they be construed to limit the scope of the present disclosure in any way. Although certain embodiments and examples have been provided, based on the disclosure herein, it will be apparent to those skilled in the art that changes may be made to the illustrated embodiments and examples without departing from the scope of the present disclosure.

[0263] Although the present disclosure has been shown and described with reference to various embodiments thereof, those skilled in the art will understand that various changes may be made therein in form and detail without departing from the spirit and scope of the present disclosure as defined by the appended claims and their equivalents.

Claims

1. A method performed by a user equipment (UE) in a wireless communication system, the method comprising: Receiving, from a base station, a first system information block (SIB) associated with satellite assistance information, the first SIB including first information about a serving cell ephemeris and second information about a valid duration of the serving cell ephemeris; And Receiving, from the base station, a second system information block (SIB) associated with adjacent satellite information, based on a first timer whose duration is the valid duration of the serving cell ephemeris and a second timer for obtaining the first SIB before a radio link failure (RLF), the second SIB including third information about an adjacent cell ephemeris.

2. The method according to claim 1, wherein, The valid duration of the adjacent cell ephemeris is the same as the valid duration of the serving cell ephemeris.

3. The method according to claim 1, wherein, Based on the second timer, the valid duration of the adjacent cell ephemeris is identified.

4. The method according to claim 1, wherein The valid duration of the adjacent cell ephemeris is explicitly signaled.

5. A user equipment (UE) in a wireless communication system, the UE comprising: A transceiver; And A controller coupled to the transceiver and configured to: Receiving, from a base station, a first system information block (SIB) associated with satellite assistance information, the first SIB including first information about a serving cell ephemeris and second information about a valid duration of the serving cell ephemeris; And Receiving, from the base station, a second system information block (SIB) associated with adjacent satellite information, based on a first timer whose duration is the valid duration of the serving cell ephemeris and a second timer for obtaining the first SIB before a radio link failure (RLF), the second SIB including third information about an adjacent cell ephemeris.

6. The UE according to claim 5, wherein, The valid duration of the adjacent cell ephemeris is the same as the valid duration of the serving cell ephemeris.

7. The UE according to claim 5, wherein, Based on the second timer, the valid duration of the adjacent cell ephemeris is identified.

8. The UE according to claim 5, wherein The valid duration of the adjacent cell ephemeris is explicitly signaled.

9. A method performed by a base station in a wireless communication system, the method comprising: Sending, to a user equipment (UE), a first system information block (SIB) associated with satellite assistance information, the first SIB including first information about a serving cell ephemeris and second information about a valid duration of the serving cell ephemeris; And Sending, to the UE, a second system information block (SIB) associated with adjacent satellite information, based on a first timer whose duration is the valid duration of the serving cell ephemeris and a second timer for obtaining the first SIB before a radio link failure (RLF), the second SIB including third information about an adjacent cell ephemeris.

10. The method according to claim 9, wherein, The valid duration of the adjacent cell ephemeris is the same as the valid duration of the serving cell ephemeris.

11. The method according to claim 9, wherein, Based on the second timer, the valid duration of the adjacent cell ephemeris is identified.

12. The method according to claim 9, wherein, The valid duration of the adjacent cell ephemeris is explicitly signaled.

13. A base station in a wireless communication system, the base station comprising: A transceiver; and a controller, the controller being coupled to the transceiver and configured to: send a first system information block SIB associated with satellite assistance information to a user equipment UE, the first SIB including first information about a serving cell ephemeris and second information about a valid duration of the serving cell ephemeris; and send a second system information block SIB associated with adjacent satellite information to the UE based on a first timer whose duration is the valid duration of the serving cell ephemeris and a second timer for obtaining the first SIB before a radio link failure RLF, the second SIB including third information about an adjacent cell ephemeris.

14. The base station according to claim 13, wherein, The valid duration of the adjacent cell ephemeris is the same as the valid duration of the serving cell ephemeris.

15. The base station according to claim 13, wherein, Based on the second timer, the valid duration of the adjacent cell ephemeris is identified.

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