Terminal, method, base station and communication system

Abstract

A terminal according to one aspect of the present disclosure comprising: a receiver configured to receive assistance data having a validity duration; a processor configured to: initiate a timer based on the validity duration of the received assistance data, and determine a remaining validity time of the assistance data before the timer expires; and a transmitter configured to transmit a report of the determined remaining validity time. According to one aspect of the present disclosure, ensuring an uninterrupted connection with a network even when system information broadcasts are intermittent can be achieved.

Description

TERMINAL, METHOD, BASE STATION AND COMMUNICATION SYSTEMCROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application is based on and claims priority to U.S. Provisional Application No. 63 / 680,854, filed on August 8, 2024, the contents of which are incorporated herein by reference in their entirety.

[0002] Apparatuses and methods consistent with the present disclosure relate generally to communications, more specifically, methods, systems, and devices for acquisition of assistance data in radio communication systems and nodes.

[0003] In some radio communication systems, such as satellite communication systems, a terminal relies on assistance data to manage the communication connection. This assistance data, which may include satellite ephemeris and radio parameters, is often associated with a validity duration, and a timer is initiated upon its acquisition (Non Patent Literature 1). The terminal must refresh this data before the timer expires to maintain the connection. In some existing systems, such as 3GPP New Radio (NR), a terminal can request system information blocks through dedicated signaling on an on-demand basis.

[0004] 3GPP TS 38.331 V18.2.0, “NR; Radio Resource Control (RRC); Protocol specification”

[0005] However, a problem arises in satellite systems, particularly those with store-and-forward architectures, where system information broadcasts can become intermittent and infrequent. This intermittency, which may also be caused by energy-saving objectives, creates a significant challenge for the terminal to acquire updated assistance data in a timely manner. If the terminal fails to refresh the assistance data before its validity timer expires, it may lead to connection disruptions and the need to re-initiate the entire connection establishment process, causing inefficiency and delays.

[0006] Thus, one object of the present disclosure is to provide a terminal, a method, a base station and a communication system that can ensure an uninterrupted connection with a network even when system information broadcasts are intermittent.

[0007] A terminal according to one aspect of the present disclosure comprising: a receiver configured to receive assistance data having a validity duration; a processor configured to: initiate a timer based on the validity duration of the received assistance data, and determine a remaining validity time of the assistance data before the timer expires; and a transmitter configured to transmit a report of the determined remaining validity time.

[0008] According to one aspect of the present disclosure, ensuring an uninterrupted connection with a network even when system information broadcasts are intermittent can be achieved.

[0009] FIG. 1 is a schematic diagram illustrating a system for some embodiments of the present disclosure.

[0010] FIG. 2 is a schematic diagram illustrating an exemplary functional configuration of each device for some embodiments of the present disclosure.

[0011] FIG. 3 is a schematic diagram illustrating an exemplary hardware configuration of each device for some embodiments of the present disclosure.

[0012] FIG. 4 is a schematic diagram illustrating an exemplary flow chart of a threshold driven triggering of the remaining validity.

[0013] FIG. 5 is a schematic diagram illustrating an exemplary flow chart of a connection quality driven triggering of reporting.

[0014] FIG. 6 is a schematic diagram illustrating an exemplary flow chart of provisioning of assistance data based on reported validity time and / or indicated channel quality issues.

[0015] FIG. 7 is a schematic diagram illustrating an exemplary flow chart of triggering a request for assistance data of neighboring satellites based on anticipated switching.

[0016] FIG. 8 is a schematic diagram illustrating an exemplary flow chart of triggering of assistance data uploading.

[0017] FIG. 9 is a schematic diagram illustrating an exemplary flow chart of delivery of assistance data of neighboring satellites.

[0018] The present disclosure may introduce a method and apparatus for acquisition of information such as assistance data in radio communication systems and nodes.

[0019] Reference will now be made in detail to exemplary embodiments, examples of which are illustrated in the accompanying drawings. The following description refers to the accompanying drawings in which the same numbers in different drawings represent the same or similar elements unless otherwise represented. The implementations set forth in the following description of exemplary embodiments do not represent all implementations consistent with the present disclosure. Instead, they are merely examples of systems, apparatuses, and methods consistent with aspects related to the present disclosure as recited in the appended claims.

[0020] In the present disclosure, "A / B," “A and / or B” and "at least one of A and B" may be used interchangeably. In the present disclosure, "A / B / C," “A and / or B and / or C” and "at least one of A, B and C" may be used interchangeably.

[0021] (System) FIG. 1 is a schematic diagram illustrating a system for some embodiments of the present disclosure. The system 1 may be a system implementing a communication using Long Term Evolution (LTE), 5th generation mobile communication system New Radio (5G NR) and so on the specifications of which have been drafted by Third Generation Partnership Project (3GPP). The system 1 may include one or more user equipment (UE) 10, one or more base stations (BS) 20, one or more core networks (CN) 30.

[0022] In the present disclosure, terms “system,” “radio system,” “radio communication system,” “radio interface,” and “network” are used as general terms which include one or both of terrestrial network systems and non-terrestrial network (NTN) systems such as satellite systems. In the present disclosure, these terms may be used interchangeably.

[0023] The UE 10 may be a terminal supporting at least one of communication schemes such as LTE, 5G NR, and so on. The UE 10 may be connected to at least one of plurality of BS 20. The UE 10 may take any form, including but not limited to, a vehicle, a component mounted in a vehicle, a road-side unit, a laptop computer, a wireless terminal including a mobile phone, a wireless handheld device, or wireless personal device.

[0024] In the present disclosure, a UE, a mobile station, a mobile node and a terminal may be used interchangeably.

[0025] The plurality of base stations 10 may be connected each other by a wired connection (for example, optical fiber) or a wireless connection (for example, an NR communication). The base station 10 may be connected to a core network 30 through another base station 10 or directly.

[0026] In the present disclosure, a BS may be referred to as the terms such as a NodeB, an eNodeB (eNB), a gNodeB (gNB), a radio access network (RAN), a carrier, a component carrier, a sector, a cell, a cell group, a super cell, a macro cell, a small cell, a femto cell, a pico cell, and so on. In the present disclosure, a network may mean an apparatus (for example, a BS) included in the network.

[0027] In the present disclosure, a term “node” is used as a general term which includes user equipment (UE), a relay node, a vehicle mounted module, a station, a network infrastructure node such as a base station (BS), a roadside unit, a repeater, a transponder, a wireless router, a controller, an access point, a transmission point (TP), a reception point (RP), a transmission / reception point (TRP), a panel, and sub-systems thereof. In the present disclosure, these entities (apparatuses, devices) may be used interchangeably.

[0028] The communication between UE 10 and BS 20 may be transferred via one or more apparatuses for NTN, e.g., a Geostationary Earth Orbit (GEO) satellite, a Medium-Earth Orbit (MEO), a Low Earth Orbit (LEO) satellite, a High Altitude Platform Station (HAPS), an NTN payload and an NTN gateway. In the present disclosure, the BS 20 may include a BS in a terrestrial network and / or a BS in NTN (or the BS on / within the above one or more apparatuses for NTN). In the present disclosure, the BS and the above one or more apparatuses for NTN may be used interchangeably.

[0029] The NTN (or the system 1) may provide a non-terrestrial NR access to the UE 10 by means of the NTN payload and the NTN Gateway. A wireless link between the NTN payload and the UE 10 may be called as a service link, and a wireless link between the NTN Gateway and the NTN payload may be called as a feeder link.

[0030] A satellite, such as GEO, MEO, LEO and HAPS, may be a space-borne vehicle orbiting the Earth embarking the NTN payload. The NTN payload may be a network node, embarked on board the satellite, providing connectivity functions, between the service link and the feeder link. The NTN Gateway may be an earth station located at the surface of the earth, providing connectivity to the NTN payload using the feeder link.

[0031] The NTN payload may transparently forward the radio protocol received from the UE 10 (via the service link) to the NTN Gateway (via the feeder link) and vice-versa.

[0032] A satellite may directly communicate with another satellite via inter-satellite link (ISL). The ISL may work as a satellite backhaul.

[0033] The core network 30 may include at least one of Evolved Packet Core (EPC), 5G Core Network (5GCN), and so on.

[0034] In the system 1, an orthogonal frequency division multiplexing (OFDM)-based wireless access scheme may be used. For example, in at least one of the downlink (DL) communication and the uplink (UL) communication, Cyclic Prefix OFDM (CP-OFDM), Discrete Fourier Transform Spread OFDM (DFT-s-OFDM), Orthogonal Frequency Division Multiple Access (OFDMA), Single Carrier Frequency Division Multiple Access (SC-FDMA), and the like may be used.

[0035] (Functional / Hardware Configuration of Device) FIG. 2 is a schematic diagram illustrating an exemplary functional configuration of each device for some embodiments of the present disclosure. For example, the UE 10 may have a control unit 110, a communication unit 120, an input / output unit 130, and a storage unit 140.

[0036] The BS 20 may have similar functional configurations. For this reason, in this exemplary functional configuration, the sign of the functional block corresponding to each device is also shown with the largest digit of the sign indicating each device (e.g., the largest digit "2" of "20" for BS 20) replaced with "1". In the following, the functional blocks relating to the UE 10 will be explained, but it is understood that the same explanation applies to other devices as well.

[0037] In this example, the functional blocks of the characteristic parts of the system are mainly shown, and each device may also have other functional blocks necessary for other processes. The configuration may also not include some of the functional blocks.

[0038] The control unit 110 implements control of the UE 10 and provides various functions. For example, the control unit 110 may control communication with other devices via the communication unit 120. The control unit 110 may also obtain information necessary for processing based on information received via the communication unit 120. The control unit 110 may be referred to as a processing unit.

[0039] The communication unit 120 communicates (transmits / receives) with other devices via wired / wireless communication. The communication unit 120 may obtain information from the received signal and output it to the control unit 110, or it may convert information input from the control unit 110 into a signal and transmit it. Communication unit 120 may be referred to as a transmitter, receiver, or transmitter / receiver.

[0040] The input / output unit 130 may include an input unit that accepts input from a person. The input unit may be connected to a predetermined device, storage medium, etc., and may accept data input. The input unit may output input results to, for example, the control unit 110.

[0041] The input / output unit 130 may also include an output unit that outputs data, content, etc. in a format that can be perceived by humans. The output unit may comprise a display unit that displays images, an audio output unit that outputs sound, and the like.

[0042] The storage unit 140 stores (holds) various information used by the management unit 10 for processing. The control unit 110 may instruct the storage unit 140 to read and write data.

[0043] The functional blocks (components) in FIG. 2 may be implemented in arbitrary combinations of at least one of hardware and software. Each functional block may be realized by one apparatus that is physically or logically coupled, or may be realized by directly or indirectly connecting two or more physically or logically separate apparatuses (for example, via wire, wireless, or the like) and using these apparatuses. The functional blocks may be implemented by combining softwares into the apparatus described above or the plurality of apparatuses described above.

[0044] FIG. 3 is a schematic diagram illustrating an exemplary hardware configuration of each device for some embodiments of the present disclosure. For example, the UE 10, the BS 20, and the other devices in the present disclosure may function as a computer that executes the processes of the radio communication method(s) in the present disclosure. Each device may have an antenna 910, a Radio Frequency (RF) circuit 920, a processor 930, a network interface 940, an input device / output device 950, a memory 960, and a storage 970.

[0045] For example, the above control unit X10 (e.g., X = 1, 2; same below) described above may be implemented by the processor 930. The communication unit X20 may be implemented by the antenna 910 / RF circuit 920 / network interface 940. The input / output unit X30 may be implemented by the input device / output device 950. The storage unit X40 may be implemented by the memory 960 / storage 970.

[0046] The hardware configuration of each device may be configured to include one or more of the elements shown in this exemplary hardware configuration, or may be configured without some of the elements. For example, the UE 10 may not have a network interface 940.

[0047] The antenna 910 converts signals into radio waves and radiates said radio waves into space. The antenna 910 also receives radio waves in space and converts said radio waves into signals. The antenna 910 may be mounted in plurality, may include a transmitting antenna and a receiving antenna, or may include a single antenna for transmitting and receiving. The antenna 910 may include a directional antenna or may include multiple antenna elements. The antenna 910 may include one or more antenna elements and may enable different input-output antenna configurations.

[0048] The RF circuit 920 performs analog processing of signals transmitted and received via antenna 910. The RF circuit 920 may include filters (e.g., high frequency filters, low pass filters), amplifiers, modulators, frequency synthesizers, analog-to-digital conversion circuit, digital-analog conversion circuit, Fast Fourier Transform (FFT) / Inverse Fast Fourier Transform (IFFT) processing circuit, etc.

[0049] The RF circuit 920 may perform amplification, filter processing, demodulation to a baseband signal, etc. on the received radio frequency band signal and output to processor 930 RF circuit 920 may perform modulation to a radio frequency band, filter processing, amplification and transmit the radio frequency band signals via the transmitter / receiver antenna 910. The RF circuit 920 may perform physical layer processing (e.g., processing of lower functions of the physical layer), and may perform beamforming processing such as analog beamforming and digital beamforming processing.

[0050] The processor 930 may control the entire device. The processor 930 may read programs (program code), software (software modules), data, and the like from the storage 970 to the memory 960 and perform various processes according to these. For example, the processor 930 may execute and control an operating system (OS) program that is loaded into the memory 960. The programs are used to allow computers to execute at least part of methods (operations) shown in embodiments of the present disclosure. For example, the control unit 110 (210) may be implemented by control programs that are stored in the memory 960 and that operate on the processor 930, and other functional blocks may be implemented likewise.

[0051] The processor 930 may be configured by a central processing unit (CPU), which may include interfaces to peripheral devices, control units, arithmetic units, registers, and the like. The processor 930 may also be a microprocessor, Digital Signal Processor (DSP), Application Specific Integrated Circuit (ASIC), Programmable Logic Device (PLD), Field Programmable Gate Array (FPGA), etc.

[0052] The processor 930 may perform digital processing of signals transmitted and received via the antenna 910 and the RF circuit 920. Said digital processing may include physical layer processing (e.g., processing of higher functions of the physical layer), processing of layers above the Medium Access Control (MAC) layer, modulation, demodulation, coding, decoding, scrambling, etc. The processor 930 also processes signals sent and received via network interface 940.

[0053] The processor 930 may include a plurality of processors or may be a single processor. The multiple processors may include a baseband processor that performs the digital processing described above and one or more processors that perform other processing (e.g., overall control).

[0054] The network interface 940 may be, for example, a network adapter, which may be wired to an external network to send and receive signals.

[0055] The RF circuit 920 / baseband processor / network interface 940 may be an integral part of the RF circuit 920 / baseband processor / network interface 940. The network interface 940 may be referred to as a network controller, network card, communication module, etc.

[0056] The input device / output device 950 may comprise an input device that accepts external input (e.g., keyboard, mouse, microphone, switches, buttons, sensors, etc.), an output device that performs external output (e.g., display, speaker, Light Emitting Diode (LED) lamp etc.), and a device (e.g., a touch panel) that integrates these devices.

[0057] The memory 960 is a computer-readable, non-transitory storage medium that stores a program to be executed by the processor 930, parameters related to said program, and various other information. The memory 960 is at least one of Read Only Memory (ROM), Erasable Programmable ROM (EPROM), Electrically EPROM (EEPROM), Random Access Memory (RAM), and flash memory. All or part of the memory 960 may be contained within processor 930. Memory 960 may be referred to as a register, cache, main memory (main storage), etc.

[0058] The storage 970 is a computer-readable, non-transitory storage medium that stores a variety of information. The storage 970 may include, for example, flexible disks, floppy (registered trademark) disks, magneto-optical disks (e.g., compact disc (Compact Disc ROM (CD-ROM), digital versatile disk, Blu-ray (registered trademark) disk), a removable disk, a hard disk drive (Hard Disc Drive (HDD)), a smart card, a flash memory device (e.g., Solid State Drive (SSD)), or at least one other. The storage 970 may be referred to as an auxiliary storage device.

[0059] The processor 930, memory 960, and other devices may be connected by a bus for communicating information. A single bus may be used within a device, or different buses may be used between devices.

[0060] The BS 20 may be separated into three elements: the Radio Unit (RU), the Distributed Unit (DU), and the Central Unit (CU). The RU implements RF processing and lower functions of the physical layer. The DU implements the upper functions of the physical layer, the functions of the MAC layer, and the functions of the Radio Link Control (RLC) layer. The CU realizes the functions of the Packet Data Convergence Protocol (PDCP) layer, the Service Data Adaptation Protocol (SDAP), and the Radio Resource Control (RRC) layer.

[0061] In this disclosure, BS 20 may include one device that realizes all the functions of RU, DU and CU, or may include multiple devices that each realize some of the functions of RU, DU and CU.

[0062] Other devices in the present disclosure may also be implemented by multiple devices that are physically located apart from each other. Conversely, a plurality of different devices in this disclosure may be implemented as a single device.

[0063] Some or all of the devices in this disclosure may also mean logical devices realized by virtual machines, containers, Docker, etc., or physical devices that operate such logical devices.

[0064] (Assistance-data acquisition) In many radio communication systems, timing is critical for various parameters and configurations. For example, in satellite communication systems, assistance data may play a crucial role in managing the communication connection. The 3GPP radio interfaces' assistance data may include satellite ephemeris, service start time, validity duration, and radio parameters like random-access channel configurations. This data may be transmitted through system information blocks (SIBs), such as SystemInformationBlockType31 for LTE. The procedure may begin with the mobile node determining its location, for example from a Global Navigation Satellite System (GNSS), followed by obtaining the assistance data from a broadcast instance of system information.

[0065] Once the assistance data is acquired, a timer (e.g., T317) starts, counting down to the end of its validity. The node may calculate transmission timing advance based on the computation of the distance between the satellite and the mobile node. The computation may make use of the satellite's position obtained from the ephemeris information and the mobile node’s own position. The purpose is to compensate for the propagation delay in the link with the satellite. The mobile node then initiates a random-access attempt with or following the service's start time. If the timer expires before the random-access attempt, the mobile node must reacquire the assistance data because access is permitted only when timing advance information is available.

[0066] System information provision in satellite communication will be intermittent due to 3GPP Rel-19 work item for store-and-forward communication with regenerative payloads on satellites. Unlike transparent payloads, this architecture doesn't guarantee simultaneous satellite-to-node and satellite-to-ground station links. Additionally, long communication gaps may be possible because coverage may not be continuous; a satellite's departure does not ensure immediate service from another. Within 3GPP Rel-19 work item scope, energy saving objectives further may mean that satellite transmissions may be deliberately intermittent, such as transmitting only in a subset of time slots. However, these advancements may lead to longer system information acquisition times. This may complicate mobility procedures, such as transferring connections from one cell to another and between satellites because it may delay establishing connections to new cells during cell re-selections or re-establishing connections within the same cell.

[0067] The state-of-the art technique described in the 3GPP specifications requires the mobile node to refresh its system information before the T317 validity timer expires. If the mobile node fails in updating the system information in time, it will start another timer denoted as T318. If the T318 timer also expires without the system information being updated, the mobile node will revert to idle mode and consider the cell as barred (or consider radio link failure to be detected for the cell). This scenario necessitates a re-initiation of the connection establishment process from the beginning.

[0068] The core concept of some embodiments in the present disclosure may involve at least one of the following ideas: - Proactively reporting the remaining validity time of information, such as assistance-data, to the satellite before the validity time expires, coupled with a request for system information through dedicated signaling, e.g., when system information broadcast instances are intermittent and / or infrequent. - Requesting information, for example assistance-data of a nearby satellite through dedicated signaling from the serving satellite, particularly in situations where a switch to another satellite is anticipated, but the departure of the current satellite does not guarantee immediate service from another.

[0069] The closest prior art may be an on-demand system information mechanism in the 3GPP NR radio interface, where system information blocks are provided by the serving cell through dedicated signaling upon request from a mobile node. This approach is necessitated by the inefficiency of broadcasting information in a beamforming-based system with narrow lobes due to high operating frequencies.

[0070] The first innovative aspect of some embodiments in the present disclosure may differ from the prior-art due to inclusion of the remaining validity time of the assistance-data in the request. This may allow for a decision-making process at the satellite to determine whether to use dedicated signaling or wait for the next broadcast instance, based on the sufficiency of the remaining time.

[0071] The second innovative aspect of some embodiments in the present disclosure may differ from the prior art because the system information provided may pertain to cells other than the serving cell based on the anticipated cell and / or satellite switch. Additionally, some embodiments in the present disclosure may introduce a network entity for the collection and distribution of system information, which may be beneficial in store-and-forward satellite architectures where feeder link connections may be neither continuous nor guaranteed.

[0072] The most closely related existing technology to the second innovative aspect may be the broadcasted neighbor cell information found in the 3GPP LTE / NR standards. In these standards, a cell may provide information about its neighboring cells, such as their operating frequencies, to enable mobile nodes to perform measurements. The essential difference with the second innovative aspect may lie in the satellite's role because it may provide by means of dedicated signaling detailed information regarding the configurations and radio parameters of adjacent satellites, thereby assisting the mobile node in accessing these satellites more efficiently.

[0073] Some embodiments in the present disclosure may present an improvement over existing techniques by ensuring an uninterrupted connection with the satellite network, even when system information broadcast instances are intermittent and / or infrequent. This may minimize the risk of connection disruptions and reduce the need to frequent transitions between idle and connected modes, thereby lowering the system's overall overhead. The primary advantage of some embodiments in the present disclosure may be the reduction in signaling overhead but it may also lead to a more dynamic and responsive satellite communication system that can adapt to changing conditions and maintain more consistent service quality.

[0074] (Method) The methods (wireless (or radio) communication methods, control methods) described below may be applied in the system 1 described above. A transmitter (or receiver) in the methods may be the UE 10 and may be considered as a UE. A receiver (or transmitter) in the methods may be the BS 20 and may be considered as a BS.

[0075] The present disclosure discloses a method and apparatus for acquisition of information such as assistance data information in radio communication systems and nodes.

[0076] The method can be applied to any wireless communication system that makes use of assistance-data acquisition through system information but, in the rest of the disclosure, the method is exemplified with, but not limited to, non-terrestrial mobile radio communication systems, such as 3GPP LTE and / or NR radio access technology, where satellite assistance data provisioning is supported.

[0077] The method described in the disclosure is primarily exemplified using satellite assistance data. However, the method is applicable to any form of time-sensitive system information, for example, positioning, network slicing, or energy saving related information, which is associated with a validity time.

[0078] In the first embodiment, the node or satellite may transmit assistance data that may be incorporated within a system information block. Upon receiving the assistance data, the mobile node may initiate a timer, which may be configured to the validity duration of the data. The other node, for example mobile node, may calculate and report the remaining validity time to the node or satellite before the timer expires. The remaining time may be determined by subtracting the current timer value from the configured validity duration.

[0079] In another embodiment, the trigger for the reporting may be controlled with a (pre-)configured threshold where, for example, the report may be issued when the absolute remaining validity time falls below a threshold or, alternatively, the remaining validity time exceeds a certain (pre-)configured percentage of the configured validity time. The threshold configuration may be provided as a pre-configuration, in a Subscriber Identity Module (SIM), embedded in the assistance data, or via signaling from the serving satellite. The embodiment is exemplified in Figure 4 where a threshold is used.

[0080] In another embodiment, deteriorated communication quality in one node (e.g., a mobile node), such as indications of potential risk of losing synchronization with the other node (e.g. satellite), impaired signal quality or strength, entering specific geographical regions (e.g., satellite coverage holes), anticipated connection issues based on the current satellite’s ephemeris and the mobile node’s position, may trigger reporting of anticipated issues with connection quality, e.g., a need for connection re-establishment. A connection re-establishment may also be triggered, for example, when security configurations need to be refreshed in 3GPP radio interfaces in which case the assistance data delivery may be followed by updated security parameters and / or security mode. The indication may be embedded in the same message as the remaining validity time or included in another message such as a separate stand-alone message. Examples of possible messages may be early data transmission requests and reporting of user equipment information in 3GPP radio interfaces. The purpose of the indication may be to inform the satellite of a need for assistance data delivery via dedicated signaling to ensure, e.g., successful connection re-establishment. The embodiment is exemplified in Figure 5 where connection quality driven triggering is used for indication of impaired connection quality.

[0081] In another embodiment, upon reception of the report, one node (e.g., the satellite) may assess the reported remaining validity time of assistance data against the system information broadcast schedule. If the upcoming broadcast instance (transmission) of assistance data falls beyond the timer's expiration, the satellite may proactively transmit the assistance data to the mobile node via dedicated signaling. If the scheduled broadcast instance precedes the timer's expiration time, the satellite may ignore the report, in which case the mobile node may acquire the assistance data from the system's broadcast information. The other node, e.g., mobile node, upon receiving the assistance data, may initiate a timer.

[0082] In another embodiment, the satellite may receive an indication of anticipated issues with connection quality and the satellite may proactively transmit the assistance data to the mobile node via dedicated signaling. The mobile node, upon receiving the assistance data, may initiate a timer.

[0083] An example message for assistance data delivery may be radio resource control protocol’s reconfiguration message in 3GPP radio interfaces. The assistance data may be delivered as a contained octet string or as a message extension.

[0084] The above described two embodiments are exemplified in Figure 6 where the satellite receives may report of remaining validity time and / or indications of connection quality deterioration.

[0085] In another embodiment, the satellite may receive a report of remaining validity time and / or an indication of anticipated issues with connection quality and the satellite may release the ongoing connection, for example, by sending a radio resource control protocol’s connection release message via dedicated signaling. The mobile node, upon receiving the message, may transition to idle mode.

[0086] In another embodiment, the mobile node may request neighboring satellite / cell assistance data from the current satellite or cell to prepare for potential cell or satellite switching. The satellite may retrieve this data by querying a network entity's database through a satellite-to-ground link or feeder link, and / or by receiving the data from neighboring satellite(s) via inter-satellite link. Upon receiving the data via dedicated signaling, the mobile node may initiate a timer. In an example, the mobile node may anticipate potential cell or satellite switching based on the current satellite’s ephemeris and the mobile node’s position. The embodiment is exemplified in Figure 7 where anticipated cell or satellite switching may trigger a request for assistance data of neighboring satellites / cells.

[0087] In another embodiment, the satellite may upload its assistance data to the database whenever the assistance-data is changed, and the feeder link is available. The satellite may store the latest point of uploading time in its memory and compare the latest uploading time with the instance of time when the assistance data is changed. If the assistance data is changed after the last uploading, the satellite may trigger uploading of assistance data to the database. The embodiment is exemplified in Figure 8 when changed assistance data may trigger uploading of assistance data to the database via feeder link.

[0088] In the present disclosure, the database may be an apparatus located in the core network and / or outside the core network.

[0089] In another embodiment, the satellite may cache neighboring satellites' assistance data locally in the satellite after querying the database, ensuring availability of assistance data even without a feeder link and inter-satellite link. Upon reception of a request for assistance data of neighboring satellites, the satellite may determine whether to query the local cached data or the database via the feeder link, depending on the availability of the feeder link. The embodiment is exemplified in Figure 9 for delivery of assistance data of neighboring satellites.

[0090] In another embodiment, assistance data entries may be released from the databases and caches once their validity time expires.

[0091] While the examples in this disclosure relate to satellite and mobile node, other nodes can use embodiments in this disclosure.

[0092] The present disclosure may disclose a method and apparatus for acquisition of information such as assistance data information in radio communication systems and nodes.

[0093] Some embodiment in the present disclosure, mobile nodes may proactively report the remaining validity time of information such as assistance data to another node such as the serving satellite. This report is coupled with a request for system information through dedicated signaling, which is particularly useful when system information broadcast instances are intermittent and infrequent.

[0094] Some embodiment in the present disclosure, mobile nodes may request information such as assistance data of nearby satellites through dedicated signaling from the serving satellite. This is especially relevant in scenarios where a switch to another satellite is anticipated, but the departure of the current satellite does not ensure immediate service from the next one. This is particularly useful for store-and-forward satellite architectures with regenerative payloads.

[0095] (Supplementary Notes) Regarding embodiments of the present disclosure, the following supplementary notes are given. <Supplementary Note 1> A terminal comprising: a receiver configured to receive assistance data having a validity duration; a processor configured to: initiate a timer based on the validity duration of the received assistance data, and determine a remaining validity time of the assistance data before the timer expires; and a transmitter configured to transmit a report of the determined remaining validity time. <Supplementary Note 2> The terminal according to supplementary note 1, wherein the transmitter is configured to transmit the report when the determined remaining validity time falls below a threshold. <Supplementary Note 3> The terminal according to any one of supplementary notes 1 to 2, wherein the transmitter is configured to transmit an indication of an anticipated issue with connection quality. <Supplementary Note 4> The terminal according to any one of supplementary notes 1 to 3, wherein the transmitter is configured to transmit the indication when the connection quality falls below a threshold. <Supplementary Note 5> The terminal according to any one of supplementary notes 1 to 4, wherein the transmitter is configured to transmit, to a serving base station, a request for assistance data of a neighboring base station based on an anticipated switch to the neighboring base station. <Supplementary Note 6> The terminal according to any one of supplementary notes 1 to 5, wherein the processor is configured to determine the anticipated switch based on ephemeris information of the serving base station and a position of the terminal. <Supplementary Note 7> The terminal according to any one of supplementary notes 1 to 6, wherein the receiver is configured to receive an update of the assistance data via dedicated signaling in response to the report. <Supplementary Note 8> A method performed by a terminal, the method comprising: receiving assistance data having a validity duration; initiating a timer based on the validity duration of the received assistance data; determining a remaining validity time of the assistance data before the timer expires; and transmitting a report of the determined remaining validity time. <Supplementary Note 9> A base station comprising: a receiver configured to receive, from a terminal, a report of a remaining validity time of assistance data; a processor configured to determine, based on the received remaining validity time, whether to transmit an update of the assistance data to the terminal via dedicated signaling or via broadcast information; and a transmitter configured to transmit the update to the terminal according to the determination. <Supplementary Note 10> A communication system comprising: a terminal according to any one of supplementary notes 1 to 7; and a base station according to supplementary note 9.

[0096] (Variations) Embodiments in the present disclosure may be used for any 3GPP radio access technologies, for example, 3GPP 4G technology referred to as Long Term Evolution (LTE), 3GPP 5G technology referred to as New Radio (NR) or future 3GPP radio technology generations such as 6G. While the examples in the present disclosure relate to 3GPP technologies, embodiments in the present disclosure could be used for non-3GPP technologies, for example, Bluetooth, IEEE and its 802.11 variants, Wi-Fi, WiMAX, etc.

[0097] In the present disclosure, any signals (e.g., for indication, configuration and notification of some information) from a node to another node may be transmitted using any one or combinations of Radio Resource Control (RRC) layer signaling, Medium Access Control (MAC) layer signaling, and physical (PHY) layer signaling, even if not explicitly stated.

[0098] The RRC layer signaling may be an RRC message or an RRC information element. The MAC layer signaling may be a MAC control element (MAC CE) or a MAC Protocol Data Unit (PDU). The PHY layer signaling may be downlink control information (DCI), uplink control information (UCI), or sidelink control information (SCI).

[0099] Any parameters, values and information in the present disclosure may be indicated from a node to another node, even if not explicitly stated. In the present disclosure, “X” and “information on X” may be used interchangeably.

[0100] In the present disclosure, a time unit for radio communication may be replaced with (or interchangeably used as) another time unit for radio communication. For example, a radio frame, a subframe, a slot, a sub-slot, and a symbol all express time units for radio communication.

[0101] In the present disclosure, the terms “notify,” “report,” “indicate,” “designate,” “activate,” “deactivate,” “select,” “configure,” “pre-configure,” “update,” “determine,” etc. may be read interchangeably.

[0102] As used in the present disclosure, use of the term “or” in a list of items indicates an inclusive list. The list of items may be prefaced by a phrase such as “at least one of” or “one or more of.” For example, a list of at least one of A, B, or C includes A or B or C or AB (i.e., A and B) or AC or BC or ABC (i.e., A and B and C). Also, as used in the present disclosure, prefacing a list of conditions with the phrase “based on” shall not be construed as “based only on” the set of conditions and rather shall be construed as “based at least in part on” the set of conditions. For example, an outcome described as “based on condition A” may be based on both a condition A and a condition B without departing from the scope of the present disclosure.

[0103] In the present disclosure, the terms “comprise,” “include,” or “contain” may be used interchangeably and have the same meaning and are to be construed as inclusive and open-ended. The terms “comprise,” “include,” or “contain” may be used before a list of elements and indicate that at least all of the listed elements within the list exist but other elements that are not in the list may also be present. For example, if A comprises B and C, both {B, C} and {B, C, D} are within the scope of A.

[0104] The present disclosure, in connection with the accompanied drawings, describes example configurations that are not representative of all the examples that may be implemented or all configurations that are within the scope of the present disclosure. The term “exemplary” should not be construed as “preferred” or “advantageous compared to other examples” but rather “an illustration, an instance or an example.” By reading the present disclosure, including the description of the embodiments and the drawings, it will be appreciated by a person of ordinary skills in the art that the technology disclosed herein may be implemented using alternative embodiments. The person of ordinary skill in the art would appreciate that the embodiments, or certain features of the embodiments described herein, may be combined to arrive at yet other embodiments for practicing the technology described in the present disclosure. Thus, the disclosure is not limited to the examples and designs described herein but is to be accorded the broadest scope consistent with the principles and novel features disclosed herein.

[0105] The flowcharts and block diagrams in the figures illustrate examples of the architecture, functionality, and operation of possible implementations of systems, methods, and devices according to various embodiments. It should be noted that, in some alternative implementations, the functions noted in blocks may occur out of the order noted in the figures. For example, two blocks shown in succession may, in fact, be executed substantially concurrently, or the blocks may sometimes be executed in the reverse order, depending upon the functionality involved. Likewise, additional steps may be included in such methods, and certain steps may be omitted or combined, in methods consistent with various embodiments.

[0106] It is understood that the described embodiments are not mutually exclusive, and elements, components, materials, or steps described in connection with one example embodiment may be combined with, or eliminated from, other embodiments in suitable ways to accomplish desired design objectives. Any embodiment (two or more) used in the present disclosure may be used in combination.

[0107] Reference herein to “some embodiments” or “some exemplary embodiments” means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment. The appearance of the phrases “one embodiment,” “some embodiments” or “another embodiment” in various places in the present disclosure do not all necessarily refer to the same embodiment, nor are separate or alternative embodiments necessarily mutually exclusive of other embodiments. In the present disclosure, “an / one embodiment,” “(some) embodiments” and “another embodiment” may be used interchangeably.

[0108] The articles “a” and “an” as used in the present disclosure and the appended claims should generally be construed to mean “one or more” unless specified otherwise or clear from context to be directed to a singular form.

[0109] Unless explicitly stated otherwise, each numerical value and range in the present disclosure may be interpreted as being approximate as if the word “about” or “approximately” preceded the value of the value or range.

[0110] The term "connected" or any variation of the terms as used in the present disclosure mean all direct or indirect connections between two or more elements, and may include the presence of one or more intermediate elements between two elements that are "connected" to each other. The connection between the elements may be physical, logical, or a combination thereof. For example, "connection" may be interpreted as "access."

[0111] Although the elements in the following method claims, if any, are recited in a particular sequence, unless the claim recitations otherwise imply a particular sequence for implementing some or all of those elements, those elements are not necessarily intended to be limited to being implemented in that particular sequence.

[0112] It is appreciated that certain features of the present disclosure, which are, for clarity, described in the context of separate embodiments, may also be provided in combination in a single embodiment. Conversely, various features of the present disclosure, which are, for brevity, described in the context of a single embodiment, may also be provided separately or in any suitable sub-combination or as suitable in any other described embodiment of the present disclosure. Certain features described in the context of various embodiments are not essential features of those embodiments, unless noted as such.

[0113] It will be further understood that various modifications, alternatives, and variations in the details, materials, and arrangements of the parts which have been described and illustrated in order to explain the nature of described embodiments may be made by those skilled in the art without departing from the scope. Accordingly, the following claims embrace all such alternatives, modifications, and variations that fall within the terms of the claims.

Claims

1. A terminal comprising: a receiver configured to receive assistance data having a validity duration; a processor configured to: initiate a timer based on the validity duration of the received assistance data, and determine a remaining validity time of the assistance data before the timer expires; and a transmitter configured to transmit a report of the determined remaining validity time.

2. The terminal according to claim 1, wherein the transmitter is configured to transmit the report when the determined remaining validity time falls below a threshold.

3. The terminal according to claim 1, wherein the transmitter is configured to transmit an indication of an anticipated issue with connection quality.

4. The terminal according to claim 3, wherein the transmitter is configured to transmit the indication when the connection quality falls below a threshold.

5. The terminal according to claim 1, wherein the transmitter is configured to transmit, to a serving base station, a request for assistance data of a neighboring base station based on an anticipated switch to the neighboring base station.

6. The terminal according to claim 5, wherein the processor is configured to determine the anticipated switch based on ephemeris information of the serving base station and a position of the terminal.

7. The terminal according to claim 1, wherein the receiver is configured to receive an update of the assistance data via dedicated signaling in response to the report.

8. A method performed by a terminal, the method comprising: receiving assistance data having a validity duration; initiating a timer based on the validity duration of the received assistance data; determining a remaining validity time of the assistance data before the timer expires; and transmitting a report of the determined remaining validity time.

9. A base station comprising: a receiver configured to receive, from a terminal, a report of a remaining validity time of assistance data; a processor configured to determine, based on the received remaining validity time, whether to transmit an update of the assistance data to the terminal via dedicated signaling or via broadcast information; and a transmitter configured to transmit the update to the terminal according to the determination.

10. A communication system comprising: a terminal according to any one of claims 1 to 7; and a base station according to claim 9.

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