NTN Satellite Ephemeris, Time, Delay, and TA Management

Abstract

A method for operating a UE, comprising: receiving system information including information corresponding to position coordinates of a non-terrestrial network (NTN) gateway; information corresponding to processing delays between a user equipment (UE) and a base station (BS); and information corresponding to a reference point position; determining a timing advance based on a time (timing) difference between the reference point position and the BS; and transmitting a timing advance report based on the determined timing advance.

Description

Technical Field

[0001] The present invention generally relates to a wireless communication system, and more particularly, to NTN satellite ephemeris, time, delay, and TA management.

Background Art

[0002] In order to satisfy the demand for increased wireless data traffic after the deployment of the fourth-generation (4G) communication system, efforts have been underway to develop an improved fifth-generation (5G) or pre-5G communication system. The 5G or pre-5G communication system is also referred to as a "beyond 4G network" or a "post long term evolution (LTE) system". The 5G communication system is to be implemented in a higher frequency (mmWave) band, for example, the 60 GHz band, in order to achieve even higher data speeds. In order to reduce radio wave propagation loss and extend the transmission distance, beamforming, massive multiple-input multiple-output (MIMO), full dimensional MIMO (FD-MIMO), array antennas, analog beamforming, and massive antenna techniques are being discussed for the 5G communication system. Also, in the 5G communication system, development for system network improvement is underway based on advanced small cells, cloud radio access network (RAN), ultra-high density networks, device-to-device (D2D) communication, wireless backhaul, mobile networks, cooperative communication, coordinated multi-points (CoMP), receiver interference cancellation, etc. In the 5G system, hybrid frequency shift keying (FSK) and Feher’s quadrature amplitude modulation (FQAM) and sliding window superposition coding (SWSC) have been developed as advanced coding modulation (ACM), and filter bank multi carrier (FBMC), non-orthogonal multiple access (NOMA), and sparse code multiple access (SCMA) have been developed as advanced access technologies.

[0003] The Internet, a human-centered connection network where humans generate and consume information, is currently evolving into the Internet of Things (IoT), where distributed entities such as things exchange and process information without human intervention. The Internet of Everything (IoE), which is a combination of IoT technology and big data processing technology via a cloud server, has emerged. Technical elements such as "sensing technology", "wired / wireless communication and network infrastructure", "service interface technology", and "security technology" are required for the implementation of IoT, and M2M (machine-to-machine) communication, MTC (machine type communication), etc. have been recently studied. Such an IoT environment can provide intelligent Internet technology services that create new value for human life by collecting and analyzing data generated between connected things. IoT can be applied to various fields including smart home, smart building, smart city, smart car or connected car, smart grid, healthcare, smart household appliances, and advanced medical services through the integration and combination between existing information technology (IT) and various industrial application examples.

[0004] Accordingly, various attempts have been made to apply the 5G communication system to the IoT network. For example, technologies such as sensor network, MTC, and M2M communication are also implemented by beamforming, MIMO, and array antenna. The application of cloud RAN as the above-mentioned big data processing technology can also be regarded as an example of the integration between 5G technology and IoT technology.

[0005] As described above, the development of wireless communication systems provides various services, and thus, a method for easily providing such services is required. Summary of the Invention Means for Solving the Problems

[0006] The present invention relates to a wireless communication system, and more particularly, to a user equipment (UE). The UE includes a transceiver and a processor operably coupled to the transceiver. The transceiver is configured to receive system information including information corresponding to the position coordinates of a non-terrestrial network (NTN) gateway, information corresponding to the processing delay between the UE and a base station (BS), and information corresponding to a reference point position. The processor is configured to determine a timing advance based on the time difference between the reference point position and the BS. Also, the transceiver (transceiver) is configured to transmit a timing advance report based on the determined timing advance.

Brief Description of the Drawings

[0007] For a more complete understanding of the present disclosure and its advantages, reference is now made to the following description taken in conjunction with the accompanying drawings in which like reference numerals represent like elements.

[0008]

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DETAILED DESCRIPTION OF THE INVENTION

[0009] The present invention relates to a wireless communication system, and more particularly, to NTN satellite calendar, time, delay, and timing advance (TA) management. Further, some components of the present disclosure can use both a terrestrial network (TN) and a non-terrestrial network (NTN), and certain components greatly improve NTN performance.

[0010] A user equipment (UE) according to an embodiment of the present disclosure is proposed. The UE is configured to receive system information including information corresponding to the position coordinates of a non-terrestrial network (NTN) gateway; information corresponding to the processing delay between the UE and a base station (BS); and information corresponding to a reference point position. The UE also includes a processor operably coupled to a transceiver. The processor is configured to determine a timing advance based on the time difference between the reference point position and the BS. The transceiver is configured to transmit a timing advance report based on the determined timing advance.

[0011] In one embodiment, the transceiver is configured to automatically transmit a timing advance report, transmit a timing advance report periodically, or transmit a timing advance report according to an instruction from the BS when a condition is satisfied or a random access is performed.

[0012] In one embodiment, the transceiver is configured to transmit a timing advance report via a radio resource control (RRC) message or via a medium access control (MAC) control element (CE).

[0013] In one embodiment, the system information includes long-term satellite ephemeris data, and changes in the long-term satellite ephemeris data are transmitted via a flag.

[0014] In one embodiment, the transceiver is configured to receive the position and velocity data included in the system information at a first period and a second period, respectively.

[0015] In one embodiment, when the system information includes the disable-s-IntraSearchP parameter, the processor is configured to search for neighboring cells.

[0016] In one embodiment, the system information includes neighboring cell selection information. The processor is configured to prioritize input cells over output cells based on the neighboring cell selection information.

[0017] In one embodiment, the system information further includes elliptical cell information including the center, minor axis or semi-minor axis, and major axis or semi-major axis of the inner region of the serving cell. The processor is further configured to determine whether the UE is within the inner region of the serving cell based on the elliptical cell information and the position of the UE. When the UE is outside the inner region of the serving cell and the signal measurement value of a neighboring cell satisfies a threshold, the processor is configured to transmit a measurement report or select the neighboring cell as the serving cell.

[0018] A BS according to another embodiment of the present disclosure is proposed. The BS is configured to generate system information including information corresponding to the position coordinates of a non-terrestrial network (NTN) gateway; information corresponding to the processing delay between a user terminal (UE) and a base station; and information corresponding to a reference point position. The BS also includes a transceiver operably coupled to a processor. The transceiver is configured to transmit the system information and receive a timing advance report based on a timing advance, where the timing advance is based on the time difference between the reference point position and the base station.

[0019] In one embodiment, the transceiver is configured to automatically receive a timing advance report, receive a timing advance report periodically, or receive a timing advance report according to an instruction from the BS when a condition is satisfied or a random access is performed.

[0020] In one embodiment, the transceiver is configured to receive a timing advance report via a radio resource control (RRC) message or via a medium access control (MAC) control element (CE).

[0021] In one embodiment, the system information includes long-term satellite ephemeris data, and changes in the long-term satellite ephemeris data are transmitted via a flag.

[0022] In one embodiment, the transceiver is configured to receive the position and velocity data included in the system information at a first period and a second period, respectively.

[0023] In one embodiment, the disable-s-IntraSearchP parameter included in the system information is used for adjacent cell search.

[0024] In one embodiment, the system information includes adjacent cell selection information indicating that input cells are prioritized over output cells.

[0025] In one embodiment, the system information further includes elliptical cell information including the center, the minor axis or semi-minor axis, and the major axis or semi-major axis of the inner region of the serving cell. When an instruction that the user equipment (UE) is outside the inner region of the serving cell is received and the signal measurement value of an adjacent cell satisfies a threshold, a measurement report is received or the adjacent cell is selected as the serving cell.

[0026] A method for UE operation according to another embodiment of the present disclosure is proposed. The method includes receiving system information including information corresponding to the position coordinates of a non-terrestrial network (NTN) gateway, information corresponding to the processing delay between the UE and a base station (BS), and information corresponding to a reference point position; determining a timing advance based on the time difference between the reference point position and the BS; and transmitting a timing advance report based on the determined timing advance.

[0027] In one embodiment, the method further includes automatically transmitting a timing advance report when a condition is satisfied or random access is performed; periodically transmitting a timing advance report; or transmitting a timing advance report according to an instruction from the BS.

[0028] In one embodiment, the method includes transmitting a timing advance report via a radio resource control (RRC) message or via a medium access control (MAC) control element (CE).

[0029] In one embodiment, the system information includes long-term satellite ephemeris data, and changes in the long-term satellite ephemeris data are transmitted via a flag.

[0030] Other technical features will be apparent to those skilled in the art from the following drawings, detailed description, and claims.

[0031] Prior to the detailed description, it is desirable to explain the definitions of certain words and phrases used throughout this patent document. The term "coupled (connected)" and its derivatives refer to direct or indirect communication between two or more components, regardless of whether they are in physical contact with each other. The terms "transmit", "receive", and "communicate", and their derivatives, include both direct and indirect communication. The terms "include" and "comprise" and their derivatives mean including without limitation. "Or" is an inclusive term meaning "and / or". The terms "associated with" and its derivatives have meanings such as "include", "be included within", "be interconnected with", "enclose", "be enclosed within", "be connected to / with", "be coupled to / with", "be capable of communicating with", "cooperate with", "intervene", "arrange side by side", "approximate to", "be constrained by", "have", "have the characteristics of", "have a relationship with". The term "controller" means a device, system, or part thereof that controls at least one operation. Such a controller can also be embodied by hardware, or a combination of hardware and software and / or firmware. The functions associated with a particular controller can be centralized or distributed, locally or remotely. "At least one of" when used with a list of items means that one or more different combinations of the listed items are used, and only one item in the list may be required. For example, "at least one of A, B, and C" includes any one of the combinations of A, B, C, A and B, A and C, B and C, and A, B, and C.

[0032] Furthermore, the various functions described below are implemented or supported by one or more computer programs, each of which is configured as computer-readable program code and is implemented on a computer-readable medium. The terms "application" and "program" refer to one or more computer programs, software components, sets of instructions, procedures, functions, objects, classes, instances, related data, or portions thereof suitable for implementation of computer-readable program code. The phrase "computer-readable program code" includes all types of computer code, including source code, object code, and executable code. The "computer-readable medium" includes any type of medium that can be accessed by a computer, such as a ROM (read only memory), RAM (random access memory), hard disk drive, compact disk (CD), digital video disk (DVD), or some other type of memory. The "non-transitory" computer-readable medium excludes transient electrical signals or other communication links that transmit such signals. The non-transitory computer-readable medium includes media where data can be permanently stored and media where data can be stored and subsequently overwritten, such as rewritable optical disks and removable memory devices.

[0033] Definitions for other predetermined words and phrases are provided throughout the patent document. Those skilled in the art will understand, if not most of the time, that such definitions will also apply to the use of the words and phrases so defined before and after.

[0034] Recently, the momentum of 5G (5th generation) or NR (new radio) mobile communications has been accelerating along with all the technical activities worldwide for various candidate technologies from industry and academia. Potential enablers of 5G / NR mobile communications include large antenna technologies from conventional cellular frequency bands to high-frequency bands that provide beamforming gains and support enhanced capabilities, and new waveforms for flexibly accommodating various services / applications with different requirements (e.g., new radio access technologies (RATs), new multiple access schemes for supporting massive connectivity, etc.).

[0035] Figures 1 through 21 discussed below, and the various embodiments used to describe the principles of the present disclosure in this patent document, are merely examples and should in no way be regarded as limiting the scope of the present disclosure. Those skilled in the art will understand that the principles of the present disclosure can be implemented as any appropriately configured system or device.

[0036] The following documents are incorporated by reference within the present disclosure as described herein in their entirety: 3GPP (Registered Trademark), TR 38.811 v15.2.0, "Study on NR to Support Non-Terrestrial Networks"; 3GPP (Registered Trademark), TR 38.821 v16.0.0, "Solutions for NR to Support Non-Terrestrial Networks (NTN)"; 3GPP (Registered Trademark), TS 38.212 v15.8.0, "5G; NR; Multiplexing and Channel Coding"; 3GPP (Registered Trademark), TS 38.211 v15.8.0, "5G; NR; Physical Channels and Modulation"; 3GPP (Registered Trademark) TS 38.321 v16.2.0, "NR; Medium Access Control (MAC) Protocol Specification"; and 3GPP (Registered Trademark) TS 38.331 v16.2.0, "NR; Radio Resource Control (RRC) Protocol Specification".

[0037] The following FIGS. 1 to 3 illustrate various embodiments implemented through the use of orthogonal frequency division multiplexing (OFDM) or orthogonal frequency division multiple access (OFDMA) communication techniques in a wireless communication system. The content of FIGS. 1 to 3 is not meant to imply physical or structural limitations on the manner in which other embodiments are implemented. Other embodiments of the present disclosure may be implemented by any suitably configured communication system.

[0038] FIG. 1 illustrates an exemplary wireless network according to an embodiment of the present disclosure. The embodiment of the wireless network 100 illustrated in FIG. 1 is for illustrative purposes only. Other embodiments of the wireless network 100 that do not depart from the scope of the present disclosure may be used.

[0039] As illustrated in FIG. 1, the wireless network 100 includes gNB 101 (e.g., a base station (BS)), gNB 102, and gNB 103. gNB 101 communicates with gNB 102 and gNB 103. Also, gNB 101 communicates with at least one network 130 such as the Internet, a private Internet protocol (IP) network, or another data network.

[0040] gNB 102 provides wireless wide-area access to network 130 for a first plurality of user equipment (UEs) within the application area 120 of gNB 102. The first plurality of UEs includes UE 111 located within a small business premises; UE 112 located within an enterprise entity (E); UE 113 located within a WiFi hotspot (HS); UE 114 located within a first residence (R); UE 115 located within a second residence (R); and UE 116 which is also a mobile device (M) such as a mobile phone, wireless laptop, or wireless PDA. gNB 103 provides wireless wide-area access to network 130 for a second plurality of UEs within the coverage area 125 of gNB 103. The second plurality of UEs includes UE 115 and UE 116. In some embodiments, one or more of gNBs 101-103 can communicate with each other and with UEs 111-116 using 5G / NR, LTE (long term evolution), LTE-advanced (LTE-A), WiMAX, WiFi, or other wireless communication techniques.

[0041] Depending on the network type, the term "base station" or "BS" can refer to any component (or set of components) configured to provide wireless access to a network, such as a transmission point (TP), a transmit-receive point (TRP), an enhanced base station (eNodeB or eNB), a 5G base station (gNB), a macrocell, a femtocell, a Wi-Fi access point (AP), or other wireless-capable device. The base station can provide wireless access via one or more wireless communication protocols, such as 3GPP (registered trademark) New Radio Interface / Access (NR), LTE (long term evolution), LTE-Advanced (LTE-A), High-Speed Packet Access (HSPA), Wi-Fi 802.11a / b / g / n / ac, etc. For convenience, the terms "BS" and "TRP" are used interchangeably in this patent document to refer to the network infrastructure components that provide wireless access to remote terminals. Also, depending on the network type, the term "user equipment" or "UE" refers to any component such as a "mobile station", "subscriber station", "remote terminal", "wireless terminal", "receive point", or "user device". For convenience, the terms "user device" and "UE" are used in this patent document to refer to a remote wireless device that wirelessly accesses the BS, whether the UE is a mobile device (such as a mobile phone or smartphone) or is generally regarded as a fixed device (such as a desktop computer or vending machine).

[0042] The dashed lines indicate the approximate extent of the coverage areas 120 and 125, shown generally circular for illustrative and explanatory purposes only. It will be clearly understood that coverage areas associated with a gNB, such as coverage areas 120 and 125, have other shapes, including irregular shapes, due to variations in the wireless environment associated with natural and man-made obstacles and the configuration of the gNB.

[0043] As described in more detail below, one or more of UEs 111-116 receive system information including information corresponding to the location coordinates of a non-terrestrial network (NTN) gateway, information corresponding to the processing delay between the UE and the base station (BS), and information corresponding to a reference point location, determine a timing advance based on the time difference between the reference point location and the BS, and include a circuit, program, or a combination thereof that transmits a timing advance report based on the determined timing advance. One or more of gNBs 101-103 generate system information including information corresponding to the location coordinates of a non-terrestrial network (NTN) gateway, information corresponding to the processing delay between the user equipment (UE) and the base station, and information corresponding to a reference point location, and include a circuit, program, or a combination thereof that receives a timing advance report based on the timing advance, where the timing advance is based on the difference between the reference point location and the base station.

[0044] As discussed in more detail below, the wireless network 100 can enable communication via one or more communication satellites 104 existing in the Earth's orbit. The communication satellite 104 can communicate directly with BSs 102 and 103, for example, in situations where BSs 102 and 103 are located far away, or in different cases, cross fronthaul and / or backhaul connections, or in addition to such connections, where it is necessary to attempt a network access connection, to provide network access. Various UEs (e.g., represented as UE 116) can communicate directly with at least a part of the communication satellite 104 and / or perform localization, for example, to receive location information or coordinates.

[0045] FIG. 1 illustrates an example of a wireless network, but FIG. 1 can have various modifications. For example, the wireless network can include any number of gNBs and any number of UEs through any suitable arrangement. Also, gNB 101 can communicate directly with any number of UEs and provide the UEs with wireless wide-area access to network 130. Similarly, each of gNBs 102-103 can communicate directly with network 130 and provide the UEs with direct wireless wide-area access to network 130. Also, gNBs 101, 102, and / or 103 can provide access to other or additional external networks, such as an external telephone network or different types of data networks.

[0046] FIG. 2 illustrates an exemplary gNB 102 according to an embodiment of the present disclosure. The embodiment of gNB 102 illustrated in FIG. 2 is merely exemplary, and gNBs 101 and 103 in FIG. 1 are the same or have similar configurations. However, gNBs are provided in a wide range of configurations, and FIG. 2 does not limit the scope of the present disclosure to a specific implementation example of the gNB.

[0047] As illustrated in FIG. 2, gNB 102 includes multiple antennas 205a-205n, multiple radio frequency (RF) transceivers 210a-210n, a transmit (TX) processing circuit 215, and a receive (RX) processing circuit 220. Also, gNB 102 includes a controller / processor 225, a memory 230, and a backhaul or network interface 235.

[0048] The RF transceivers 210a - 210n receive incoming RF signals, such as signals transmitted by UEs within the network 100 from the antennas 205a - 205n. The RF transceivers 210a - 210n down - convert the incoming RF signals to generate IF signals or baseband signals. The IF signal or baseband signal is transmitted to the RX processing circuit 220, and the RX processing circuit 220 generates a processed baseband signal by filtering, decoding, and / or binary - evolving the baseband or IF signal. The RX processing circuit 220 transmits the processed baseband signal to the controller / processor 225 for additional processing.

[0049] The TX processing circuit 215 receives analog or digital data (such as voice data, web data, e - mail, or interactive video game data) from the controller / processor 225. The TX processing circuit 215 encodes, multiplexes, and / or binary - evolves the outgoing baseband data to generate a processed baseband or IF signal. The RF transceivers 210a - 210n receive the processed outgoing baseband or IF signal from the TX processing circuit 215 and up - convert the baseband or IF signal to be transmitted via the antennas 205a - 205n to an RF signal.

[0050] The controller / processor 225 may include one or more processors or other processing devices that control the overall operation of the gNB 102. For example, the controller / processor 225 can control the reception of forward - channel signals and the transmission of reverse - channel signals by the RF transceivers 210a - 210n, the RX processing circuit 220, and the TX processing circuit 215 according to well - known principles. The controller / processor 225 can also support additional functions such as advanced wireless communication functions. For example, the controller / processor 225 can support beamforming or directional routing operations that differentially weight outgoing signals to effectively direct transmitted and received signals to / from the multiple antennas 205a - 205n in a desired direction. Any one of a wide range of other functions can be supported within the gNB 102 by the controller / processor 225.

[0051] In addition, the controller / processor 225 can also perform programs and other processes that are resident in the memory 230 like an OS. The controller / processor 225 can move data in and out of the memory 230 when required by the execution process.

[0052] The controller / processor 225 is also connected to the backhaul or network interface 235. The backhaul or network interface 235 enables the gNB 102 to communicate with other devices or systems via a backhaul connection or a network. The interface 235 can support communication via any suitable wired or wireless connection. For example, when the gNB 102 is implemented as part of a cellular communication system (such as one that supports 5G / NR, LTE / NR, or LTE-A), the interface 235 enables the gNB 102 to communicate with the gNB via a wired or wireless backhaul connection. When the gNB 102 is implemented as an access point, the interface 235 can enable the gNB 102 to communicate via a wired or wireless local area network or via a wired or wireless connection to a larger network (such as the Internet). The interface 235 includes any suitable structure that supports communication via a wired or wireless connection, such as an Ethernet or an RF transceiver.

[0053] The memory 230 is coupled to the controller / processor 225. A part of the memory 230 includes RAM, and another part of the memory 230 can include flash memory or other ROM.

[0054] FIG. 2 illustrates an example of gNB 102, but various modifications can be made to FIG. 2. For example, gNB 102 can include a predetermined number of each component illustrated in FIG. 2. As a specific example, the access point can include a number of interfaces 235. As another specific example, although it is illustrated as including one instance of the TX processing circuit 215 and one instance of the RX processing circuit 220, gNB 102 can include many instances for each (such as one per RF transceiver). Also, in FIG. 2, various components can be combined, further subdivided, omitted, or additional components can be added according to specific requirements.

[0055] FIG. 3 illustrates an exemplary UE 116 according to an embodiment of the present disclosure. The embodiment of UE 116 illustrated in FIG. 3 is merely exemplary, and the UEs 111 - 115 in FIG. 1 can be identical or have similar configurations. However, UEs are implemented with a very diverse range of configurations, and FIG. 3 does not limit the scope of the present disclosure to a specific implementation example of the UE.

[0056] As illustrated in FIG. 3, UE 116 includes an antenna 305, a radio frequency (RF) transceiver 310, a TX processing circuit 315, a microphone 320, and a receive (RX) processing circuit 325. Also, UE 116 includes a speaker 330, a processor 340, an input / output (I / O) interface (IF) 345, a touch screen 350, a display 355, and a memory 360. The memory 360 includes an operating system (OS) 361 and one or more applications 362.

[0057] The RF transceiver 310 receives an incoming RF signal transmitted by the gNB of the network 100 from the antenna 305. The RF transceiver 310 down-converts the incoming RF signal to generate an intermediate frequency (IF) signal or a baseband signal. The IF signal or the baseband signal is transmitted to the RX processing circuit 325, and the RX processing circuit 325 generates a processed baseband signal by filtering, decoding, and / or binaryizing the baseband or IF signal. The RX processing circuit 325 transmits the processed baseband signal to the speaker 330 (such as voice data) or to the processor 340 (such as web browsing data).

[0058] The TX processing circuit 315 receives analog or digital voice data from the microphone 320 or other outgoing baseband data (web data, email, or interactive video game data) from the processor 340. The TX processing circuit 315 encodes, multiplexes, and / or binaryizes the outgoing baseband data to generate a processed baseband or IF signal. The RF transceiver 310 receives the processed outgoing baseband or IF signal from the TX processing circuit 315 and up-converts the baseband or IF signal transmitted via the antenna 305 to an RF signal.

[0059] The processor 340 includes one or more processors or other processing devices and can execute the OS 361 stored in the memory 360 to control the overall operation of the UE 116. For example, the processor 340 can control the reception of forward channel signals and the transmission of reverse channel signals by the RF transceiver 310, the RX processing circuit 325, and the TX processing circuit 315 according to well-known principles. In some embodiments, the processor 340 includes at least one microprocessor or microcontroller.

[0060] Also, the processor 340 receives system information including information corresponding to the location coordinates of a non-terrestrial network (NTN) gateway, information corresponding to the processing delay between the UE and the base station (BS), and information corresponding to the reference point location, determines a timing advance based on the time difference between the reference point location and the BS, and can perform other processes and programs resident in the memory 360, such as a process for transmitting a timing advance report based on the determined timing advance. The processor 340 can move data in and out of the memory 360 when requested by an executing process. In some embodiments, the processor 340 is configured to execute the application 362 based on the OS 361 or in response to a signal received from the gNB or the operator. Also, the processor 340 is coupled to an I / O interface 345 that provides the UE 116 with a connection function to other devices such as a laptop computer and a handheld computer. The I / O interface 345 is a communication path between such accessories and the processor 340.

[0061] Also, the processor 340 is coupled to a touch screen 350 and a display 355. The operator of the UE 116 can input data to the UE 116 using the touch screen 350. The display 355 is also a liquid crystal display, a light emitting diode display, or other display that renders text and / or at least limited graphics from, for example, a website.

[0062] The memory 360 is coupled to the processor 340. A part of the memory 360 includes a RAM (random access memory), and another part of the memory 360 can include a flash memory or other ROM (read-only memory).

[0063] FIG. 3 illustrates an example of UE 116, but various modifications can be made to FIG. 3. For example, many components in FIG. 3 can be combined, further subdivided, omitted, or additional components can be added according to specific requirements. As a specific example, the processor 340 can be divided into many processors such as one or more central processing units (CPUs) and one or more graphics processing units (GPUs). Also, FIG. 3 illustrates UE 116 configured as a mobile phone or smartphone, but the UE can be configured to operate as other types of mobile or fixed devices.

[0064] After the use of 4G communication systems, a 5G / NR communication system has been developed and is currently in use to meet the increasing demand for wireless data traffic and perform various vertical applications. The 5G / NR communication system is considered to be implemented in a higher frequency (mmWave) band such as 28 GHz or 60 GHz band to achieve even higher data speeds, or in a lower frequency band such as 6 GHz to enable strong coverage and mobility support. In order to reduce the radio wave loss of radio waves and extend the transmission distance, beamforming, massive MIMO (multiple-input multiple-output), full dimensional MIMO (FD-MIMO), array antennas, analog beamforming, and large-scale antenna techniques are being discussed in the 5G / NR communication system.

[0065] Also, in the 5G / NR communication system, based on advanced small cells, cloud radio access network (RAN), ultra-high density networks, D2D (device-to-device) communication, wireless backhaul, mobile networks, cooperative communication, CoMP (Coordinated Multi-Points), receiver interference cancellation, etc., the development for system network improvement is underway.

[0066] Since a given embodiment of the present disclosure can be implemented in a 5G system, reference is made to discussions of the 5G system and the frequency bands associated therewith. However, the present disclosure is not limited to the 5G system or the frequency bands associated therewith, and embodiments of the present disclosure can be used in connection with any frequency band. For example, aspects of the present disclosure can also be applied when using a 5G communication system, or 6G which can use the THz band, or subsequent versions thereof.

[0067] A communication system includes a downlink (DL) which refers to transmission from a base station or one or more transmission points to a UE, and an uplink (UL) which refers to transmission from the UE to a base station or one or more reception points.

[0068] A time unit for DL signaling or UL signaling on a cell is referred to as a slot and includes one or more symbols. A symbol also functions as an additional time unit. A frequency (or bandwidth (BW)) unit is referred to as a resource block (RB). One RB includes several subcarriers (SCs). For example, one slot has a duration of 0.5 milliseconds or 1 millisecond and includes 14 symbols, and an RB includes 12 SCs having an interval between SCs of 15 KHz or 30 KHz.

[0069] DL signals include a data signal that transmits information content, a control signal that transmits DL control information (DCI), and a reference signal (RS) also known as a pilot signal. The gNB transmits data information or DCI via an individual physical DL shared channel (PDSCH) or physical DL control channel (PCCH). The PDSCH or PDCCH can be transmitted in various numbers of slot symbols, including one slot symbol. That is, a DCI format that schedules PDSCH reception by the UE is referred to as DL DCI, and a DCI format that schedules physical uplink shared channel (PUSCH) transmission from the UE is referred to as UL DCI format.

[0070] The gNB transmits one or more of various types of RSs including channel state information RS (CSI-RS) and demodulation RS (DMRS). The CSI-RS is mainly for the purpose of the UE performing measurements and providing CSI to the gNB. For channel measurements, non-zero power CSI-RS (NZPCSI-RS) resources are used. For interference measurement reports (IMR), CSI interference measurement (CSI-IM) resources related to zero power CSI-RS (ZPCSI-RS) settings are used. The CSI process includes NZPCSI-RS and CSI-IM resources.

[0071] The UE can determine CSI-RS transmission parameters through DL control signaling such as radio resource control (RRC) signaling from the gNB or upper layer signaling. The transmission instance of CSI-RS can be indicated by DL control signaling or set through upper layer signaling. The DM-RS is transmitted only within the BW of each PDCCH or PDSCH, and the UE can use the DMRS to demodulate data and control information.

[0072] Figures 4 and 5 illustrate exemplary wireless transmission and reception paths according to the present disclosure. In the following description, the transmission path 400 may be described as being implemented within a gNB (such as gNB 102), and the reception path 500 may be described as being implemented within a UE (such as UE 116). However, it will be understood that the reception path 500 may be implemented in the gNB and the transmission path 400 may be implemented within the UE. In some embodiments, the reception path 500 is configured to assist in the codebook design and structure of a system having a 2D antenna array as described in embodiments of the present disclosure.

[0073] As shown in FIG. 4, the transmission path 400 includes a channel coding and modulation block 405, a serial-to-parallel (S-to-P) block 410, an inverse fast Fourier transform (IFFT) block 415 of size N, a parallel-to-serial (P-to-S) block 420, a cyclic prefix addition block 425, and an upconverter (UC) 430. As shown in FIG. 5, the reception path 500 includes a downconverter (DC) 555, a cyclic prefix removal block 560, a serial-to-parallel (S-to-P) block 565, a fast Fourier transform (FFT) block 570 of size N, a parallel-to-serial (P-to-S) block 575, and a channel decoding and demodulation block 580.

[0074] As shown in FIG. 4, the channel coding and modulation block 405 receives a set of information bits, applies coding (such as low-density parity-check (LDPC) coding), modulates the input bits (using QPSK (Quadrature Phase Shift Keying) or QAM (Quadrature Amplitude Modulation)), and generates a sequence of frequency-domain modulation symbols.

[0075] The serial - parallel block 410 converts the serially modulated symbols into parallel data (like demultiplexing) to generate N parallel symbol streams when N is the IFFT / FFT size used by gNB 102 and UE 116. The IFFT block 415 of size N performs an IFFT operation on the N parallel symbol streams to generate a time - domain output signal. The parallel - serial block 420 converts the parallel time - domain output symbols from the IFFT block 415 of size N into a serial time - domain signal (like multiplexing) to generate a serial time - domain signal. The periodic preamble addition block 425 inserts a periodic preamble into the time - domain signal. The up - converter 430 modulates the output of the periodic preamble addition block 425 to an RF frequency (to up - convert) for transmission over the wireless channel. The signal can be filtered in the baseband before being converted to the RF frequency.

[0076] The RF signal transmitted from gNB 102 reaches UE 116 after passing through the wireless channel, and operations opposite to those at gNB 102 are performed at UE 116.

[0077] As shown in FIG. 5, the down - converter 555 down - converts the received signal to a baseband frequency, and the periodic preamble removal block 560 removes the periodic preamble to generate a serial time - domain baseband signal. The serial - parallel block 565 converts the time - domain baseband signal into a parallel time - domain signal. The FFT block 570 of size N performs an FFT algorithm to generate N parallel frequency - domain signals. The parallel - serial block 575 converts the parallel frequency - domain signals into a sequence of modulated data symbols. The channel decoding and demodulation block 580 demodulates and decodes the modulated symbols to recover the original input data stream.

[0078] Each of gNBs 101-103 can implement a transmission path 400 similar to the transmission via the downlink to UEs 111-116 as shown in FIG. 4, and can implement a reception path 500 similar to the uplink reception from UEs 111-116 as shown in FIG. 5. Similarly, each of UEs 111-116 can implement a transmission path 400 for uplink transmission to gNBs 101-103, and can implement a reception path 500 for downlink reception from gNBs 101-103.

[0079] Each of the components in FIGS. 4 and 5 can be implemented using only hardware, or using a combination of hardware and software / firmware. As a specific example, at least some of the components in FIGS. 4 and 5 can be implemented through software, and other components can be implemented through configurable hardware or a mixture of software and configurable hardware. For example, the FFT block 570 and the IFFT block 415 are implemented as configurable software algorithms, where the value of size N can be changed depending on the implementation example.

[0080] Also, although it is described as using FFT and IFFT, this is merely an example and should not be construed as limiting the scope of the present disclosure. Other types of transforms such as discrete Fourier transform (DFT) and inverse discrete Fourier transform (IDFT) functions can be used. It can be expected that the value of variable N in the DFT and IDFT functions can be any integer (such as 1, 2, 3, 4, etc.), and the value of variable N in the FFT and IFFT functions can be any integer that is a power of 2 (such as 1, 2, 4, 8, 16, etc.).

[0081] Figures 4 and 5 illustrate examples of wireless transmission and reception paths, but various modifications to Figures 4 and 5 are possible. For example, various components in Figures 4 and 5 can be combined, further subdivided, omitted, or additional components can be added depending on specific requirements. Also, Figures 4 and 5 illustrate examples related to the types of transmission and reception paths used in a wireless network. Any other suitable structure for supporting wireless communication within the wireless network can be used.

[0082] A non-terrestrial network (NTN) refers to a network or a segment of a network that uses RF resources mounted on a communication satellite (or an unmanned aerial vehicle system platform) (e.g., communication satellite 104). Considering the ability to provide wide coverage (scope of application) and stable services, NTN is expected to ensure universal service availability and continuity. For example, NTN can support communication services for non-service areas that cannot be covered by conventional terrestrial networks, areas with limited communication services or insufficient services, devices and passengers on moving platforms, and future railway / ship / aircraft communications, etc.

[0083] In NTN, there is cell mobility, which also leads to inaccuracies in the UE's recognition of the platform's position and various types of propagation and processing delays within the system. Various delays related to platform satellite ephemeris data and knowledge related to prediction are used for more accurate estimation of timing advance (TA), leading to better pre-compensation at the UE.

[0084] Figure 6 illustrates an example of distance estimation 600 according to an embodiment of the present disclosure. The embodiment of distance estimation 600 illustrated in Figure 6 is for illustrative purposes only. Figure 6 is not limited by a specific embodiment related to distance estimation 600.

[0085] As shown in FIG. 6, the UE attempts to estimate the distance from an aerial / satellite-mounted platform (such as a satellite). Then, such a distance estimate can be used by the UE to perform any timing pre-compensation. Such knowledge can be used to determine, report, and use an appropriate timing advance.

[0086] The aerial / satellite-mounted platform acquires the position of its GNSS base at time t1. This information reaches the gNB via the NTN gateway. The gNB positions the (provisional conversion position) of the satellite within suitable system information (SI). The UE can receive the satellite position at time tN and compare the position of the satellite with its own position at time tN. FIG. 6 illustrates an aerial / satellite-mounted platform moving from left to right, but such a platform can be fixed relative to a point on the Earth's surface.

[0087] FIG. 7 illustrates an operation example 700 of satellite calendar, time, and delay management according to an embodiment of the present disclosure. The embodiment of the operation example 700 of satellite calendar, time, and delay management illustrated in FIG. 7 is for illustrative purposes only. FIG. 7 is a specific implementation example related to the operation example 700 of satellite calendar, time, and delay management and does not limit the scope of the present disclosure.

[0088] As shown in FIG. 7, the gNB receives information such as information related to satellite calendar, time, NTN type, component delay, and component measurement values, and transmits information related to transmission, signaling, and / or setting for satellite calendar, time, and delay.

[0089] FIG. 8 illustrates an example 800 of satellite calendar, time, and delay management operations according to an embodiment of the present disclosure. The embodiment of the example 800 of satellite calendar, time, and delay management operations illustrated in FIG. 8 is for illustrative purposes only. FIG. 8 is a specific implementation example related to the example 800 of satellite calendar, time, and delay management operations and does not limit the scope of the present disclosure.

[0090] As shown in FIG. 8, the airborne / satellite-mounted platform acquires its own position and time and provides the related satellite ephemeris information and time to the NTN GW and / or gNB. Entities such as the platform, NTN GW, OAM, and / or user interface provide the gNB with latency characteristics. The gNB uses the system information to transmit the related latency, time, etc. to the UE. The gNB configures and / or instructs the UE about the TA and time reporting through broadcast, groupcast / multicast, RRC, MAC, and / or PHY signaling. The UE adjusts its own TA using the information provided by the gNB. The UE reports its own time and TA to the gNB according to the configuration. The gNB adjusts the TA and transmits appropriate MAC / PHY commands to the UE for any adjustment values. The gNB transmits a time / TA reporting request through system information, groupcast / multicast, RRC, MAC, or PHY signaling, and the UE provides such a report.

[0091] Table 1 identifies examples related to various instants and latencies in connection with one or more embodiments of the present disclosure.

[0092]

Table 1

[0093] FIG. 9 illustrates an example 900 of general UE-network procedures for satellite ephemeris, time, and latency management according to an embodiment of the present disclosure. The embodiment of the example 900 of general UE-network procedures for satellite ephemeris, time, and latency management illustrated in FIG. 9 is for illustrative purposes only. FIG. 9 is a specific implementation example related to the example 900 of general UE-network procedures for satellite ephemeris, time, and latency management and does not limit the scope of the present disclosure.

[0094] In operation F9S1, as an exemplary approach, a platform that is in flight like a satellite / HAPS or orbiting (referred to as the "platform" or block 811), an NTN gateway, and a gNB exchange one or more of the latencies shown in exemplary Table 1.

[0095] In operation F9S2, as an exemplary approach, the platform utilizes real-time signaling to transmit selected satellite ephemeris data (e.g., position (x,y,z) and velocity (vx,vy,vz)) and time to the NTN gateway. As another approach, orbital parameters including time (the "epoch") are transmitted by the platform. In yet another embodiment, reference point coordinates (e.g., corresponding to the center of the cell) are also specified by the platform. As another approach, an entity inside or connected to the NTN GW, OAM system, application server, or gNB can provide the gNB with reference point coordinates based on the selected satellite ephemeris data and known satellite beam parameters (e.g., beam coverage) and time. As yet another approach, orbital parameters including time (the "epoch") are used to identify the position of the platform.

[0096] In operation F9S3, as an exemplary approach, the NTN GW uses knowledge related to the history, propagation delay, and processing delay of the selected satellite ephemeris data to predict and identify the selected satellite ephemeris data at the time when a UE receives such information from the gNB through the NTN GW and the platform at a reference point within the cell. As an alternative, the NTN-GW does not perform such a prediction and transmits the initially selected satellite ephemeris data and time received from the platform to the gNB.

[0097] In operation F9S4, as an exemplary approach, the gNB uses the knowledge related to the history of the selected satellite ephemeris data, propagation delay, and processing delay to predict and identify the selected satellite ephemeris data at the time when the UE receives such information from the gNB through the NTN GW and the platform at the in-cell reference point. As another alternative, the gNB does not perform such a prediction and utilizes the first or NTN GW-changed selected satellite ephemeris data and time.

[0098] In operation F9S5, as an exemplary approach, the gNB identifies one or more instants for the NTN GW for the final transmission to the UE, the selected satellite ephemeris data associated with the one or more instants, and the reference point position coordinates associated with the one or more instants. In other embodiments of the present disclosure, the gNB identifies the position coordinates (also simply referred to as "coordinates" in the present disclosure) for one or more NTN GWs. For example, generally, the NTN GW is suitable for a given NTN cell until feeder link conversion is required. In an exemplary implementation, the time applicability of the NTN GW for a given UE, or a set of UEs, may also be determined by the gNB and communicated to the UE by the gNB. In one embodiment of the present disclosure, the gNB configures one or more SIBs such that different information is transmitted at different setting periods, and transmits the one or more instants, the selected satellite ephemeris data associated with the one or more instants, and the reference point position coordinates associated with the one or more instants to the NTN GW and / or the NTN-GW position coordinates. For example, more long-term or event-based information such as NTN-GW position coordinates may not be transmitted as frequently, while more real-time information such as short-term satellite ephemeris data is transmitted more frequently. Also, as one exemplary approach, predetermined system information such as NTN-GW is transmitted using groupcast / multicast signaling, where a subset of the UEs in the cell (and not all UEs in the cell) receives the selected NTN-GW information.

[0099] In operation F9S5, in one embodiment of the present disclosure, the gNB broadcasts, group-casts / multi-casts, and / or specifies via UE-specific RRC signaling what parameters to directly use and whether to estimate any parameters to facilitate pre-correction, TA calculation, and TA reporting for the UE.

[0100] Examples of time that the gNB can specify include the current time observed by the gNB, the time provided by the platform (i.e., the time point when the position of the platform is determined / acquired from GNSS), and / or the time provided by the NTN GW, and the expected reception time of the SIB at the reference point. In an embodiment of the present disclosure, the time is also a complete time (e.g., hours, minutes, seconds, etc.). In other embodiments of the present disclosure, the time can be expressed in a concise manner (e.g., by avoiding larger time units such as hours and minutes).

[0101] In operation F9S1 of one embodiment of the present disclosure, the NTN GW and the gNB, as part of the configuration signaling exchange or through configuration by an OAM system, server, or user interface, set an identifier related to the future time point such as one or more of the following time points together with an instruction on whether an entity (i.e., the platform, gNB, NTN GW, or a new entity) performs the prediction related to the platform satellite ephemeris at a future time point: (i) the time point when the gNB generates the SIB message, (ii) the time point when the NTN GW receives the SIB from the gNB, (iii) the time point when the platform receives the SIB, (iv) the time point when the reference point of the cell receives the SIB, and (v) the time point when the UE receives the SIB.

[0102] In operation F9S6, as an exemplary approach, the NTN GW transmits one or more times, selected satellite ephemeris data related to the one or more times, reference point coordinates related to the one or more times, and a selected delay to the platform, and the platform transmits the information to the UE on the access / service link.

[0103] In operation F9S7, the UE acquires the received time, satellite ephemeris data, reference point coordinates, and delay.

[0104] In operation F9S8, the UE determines an appropriate timing advance as part of pre-compensation for time (and frequency) adjustment. In an exemplary embodiment of the present disclosure, by a specific method of pre-compensation, the UE estimates the time adjustment value required for uplink transmission using (i) the time difference between the reference point position and the gNB, and (ii) the time difference between the UE position and the gNB. When the period of information update related to time, satellite ephemeris data, reference point coordinates, and delay is sufficiently early to meet the accuracy requirement, the UE assumes symmetric gNB-to-UE and UE-to-gNB as an exemplary approach. In other approaches, the UE assumes asymmetric gNB-to-UE and UE-to-gNB while calculating the timing advance. More specifically, the UE utilizes or predicts the time and satellite ephemeris data at the time when its transmission is expected to be received at the gNB.

[0105] In an exemplary implementation, the UE estimates the reception time at the gNB using the following formula.

[0106] t_gNB=t_ue+2*t_gNB_to_ue_delay_observed+t_ue_to_platform_adjustment+t_platform_to_gNB_adjustment

[0107] In the above formula, t_ue_to_platform_adjustment and t_platform_to_gNB_adjustment reflect the timing adjustment due to the asymmetry of the delay caused by the different positions of the platform (and the provisional UE) during gNB-to-UE transmission and UE-to-gNB transmission. In an exemplary embodiment, the total TA applied by the UE is calculated as (2*t_gNB_to_ue_delay_observed + t_ue_to_platform_adjustment + t_platform_to_gNB_adjustment) in the above formula.

[0108] In operation F9S9, the UE performs uplink transmission using pre-compensation (e.g., UE autonomy, network assistance, or network indication). In an exemplary embodiment, the gNB uses broadcast or group cast / multicast signaling to indicate the type of pre-compensation method supported or allowed in the cell. Also, in an exemplary embodiment, the parameters used by the UE and the applicable conditions for the use of such parameters are defined inherently (e.g., through a standard specification) or explicitly set by the gNB.

[0109] In operation F9S10, as an exemplary approach, the gNB sets the TA reporting configuration for the UE through dedicated RRC signaling. As another exemplary approach, the gNB can broadcast or group cast / multicast the parameters or indicators for setting the related TA report for the UE. In one embodiment, the gNB can be set to report a full TA (i.e., a TA including gNB-to-UE delay and UE-to-gNB delay) to the UE. In other embodiments, the gNB can be set to report a TA that increases proportionally to a reference point to the UE. In other embodiments, the TA can be specified with respect to the minimum common delay of the NTN type base (e.g., the type of platform such as GEO / LEO / HAPS, and the delay calculated by the minimum distance between the platform and the UE).

[0110] In operation F9S11, the UE transmits a TA report to the gNB. As one approach, the UE can automatically transmit a TA report when a predetermined condition is satisfied (e.g., when the absolute or relative TA exceeds a certain level, or when random access is performed in a handover or non-handover situation). As another approach, the UE transmits the TA report periodically (e.g., every X ms). As yet another approach, the gNB commands the UE regarding the TA report, and the UE responds with the TA.

[0111] In operation F9S11, the TA report is transmitted via an RRC message (e.g., Measurement Report and RRC Resume) or transmitted at a lower layer (e.g., UCI or MAC Control Element) according to the gNB's setting.

[0112] For long-term satellite ephemeris data (i.e., data valid for a longer period than a few minutes or hours), the network transmits such data to the UE in operation F9S12 using various mechanisms such as broadcast, groupcast / multicast, or unicast signaling within the NTN, pre-provisioning in the UE within the SIM, or non-NTN signaling (e.g., using a conventional cellular network or Wi-Fi network). Changes in the long-term satellite ephemeris data can be transmitted via the use of a valueFlag related to a specific version of the long-term satellite ephemeris data. As an exemplary approach, the UE searches for new long-term satellite ephemeris data in the appropriate SIB only when the valueFlag changes. The updated data can be transmitted in an incremental manner (i.e., simply a change in certain parameters or an overall change in the old data). As an exemplary approach, the period of the valueFlag, the long-term satellite ephemeris data, and the change in the long-term satellite ephemeris data are controlled independently.

[0113] Regarding the time specified in the above stage, various methods are possible. In one method, the time is absolute time (for example, UTC or the time based on gNSS). In another method, in order to reduce overhead, only more detailed time is specified (for example, minutes and seconds, or seconds), and less detailed time is omitted (for example, hours, or hours and minutes). In yet another method, the absolute time is transmitted at a consistent period, or the detailed time is transmitted more frequently. In another method, when multiple times are specified through one message, one time is selected as the reference time, and all units (for example, hours, minutes, seconds, etc.), or the absolute time of the selected unit (for example, only seconds) are specified, and other non-reference times are also the times that increase in comparison with such reference time.

[0114] In an exemplary embodiment, in addition to the time points related to gNB-to-UE transmission, the time points related to UE-to-gNB transmission can also be specified. For example, an appropriate entity (for example, gNB, platform, and NTN GW, gNB is a common selection) can specify the time and location of the time point when the UE's signal is expected at the platform, NTN GW, and / or gNB. Such information enables the UE to accurately calculate the UE-to-platform delay and the platform-to-NTN GW delay.

[0115] For the platform position and velocity identified in the above stage, various methods are possible. First, the position and velocity can be the same or transmitted at different periods from each other. For example, the position can be transmitted in one period, and the velocity can be transmitted in another period. The numerical values of the position and velocity do not change to the same extent from one point in time to another. Therefore, if a certain quantity does not change suddenly, the transmission frequency of such a quantity can be reduced. Conversely, if a certain quantity changes suddenly, such a quantity must be transmitted more frequently so that the understanding of the UE related to the platform position and velocity is accurate. Also, in one method, absolute values are used. In yet another method, the absolute value is transmitted at a certain period, and the change in the value is transmitted more frequently. In still another method, when a large number of positions and a large number of velocities are identified in one message, one set of values is selected as the reference, and the other non-reference values are identified as the time increasing in such a reference time comparison. Also, when a new position is identified but a new velocity is not, the previously identified velocity is used.

[0116] FIG. 10 is a flowchart showing an exemplary gNB procedure 1000 for assisting satellite ephemeris and TA management according to an embodiment of the present disclosure. The embodiment of the exemplary gNB procedure 1000 for assisting satellite ephemeris and TA management illustrated in FIG. 10 is for illustrative purposes only. FIG. 10 is a specific implementation example related to the exemplary gNB procedure 1000 for assisting satellite ephemeris and TA management and does not limit the scope of the present disclosure.

[0117] In operation F10S1, the gNB transmits by including satellite ephemeris data with relatively longer time correlation in the system information. Such data may be included within the reference SIB of Release 16 or a new SIB of Release 17 or higher. Such SIBs are transmitted at a period known to the UEs within the cell and may be fixed or configurable. In one exemplary embodiment, the gNB identifies the NTN GW coordinates such that the UE can estimate the UE-gNB round-trip delay (RTD) or round-trip time (RTT). The transmission of NTN GW coordinates is a better choice for feeder link delay than transmission via higher accuracy and more efficient signaling. When appropriate, information related to two or more NTN GWs is identified (e.g., to assist with expected NTN GW changes). In operation F10S1 of other embodiments, the gNB identifies the total processing delay between the UE and the gNB and reflects that processing delay in both the UE-to-gNB and gNB-to-UE directions. The total processing delay includes one or more of the following: platform (e.g., satellite) processing time, NTN GW processing time, gNB processing time, and gNB-NTN-GW transmission delay. In one exemplary manner, the gNB can transmit its own coordinates via the SIB.

[0118] Prior to operation F10S1, in one embodiment of the present disclosure, the gNB exchanges messages with its NTN GW and platform and obtains normal platform and NTN GW processing times. In other ways, the gNB can obtain such times from OAM or other systems. Also, the gNB obtains or estimates the gNB-NTN-GW transmission delay.

[0119] In operation F10S2, the gNB transmits by including satellite ephemeris data having relatively shorter time correlation in the system information. Such data may be included within the Release 16 reference SIB or a new SIB of Release 17 or higher. Such SIBs are transmitted at a period known to the UEs within the cell and may be fixed or set. In an exemplary embodiment, the gNB transmits the selected elements of the satellite ephemeris data or the Earth-centered Earth-fixed (ECEF) orthogonal position coordinates (Px, Py, and Pz) (derived from the satellite ephemeris data) and optionally the instantaneous velocity (Vx, Vy, and Vz) more frequently when compared with the information mentioned in operation F10S1.

[0120] In an exemplary embodiment of the present disclosure, the absolute values of the position and velocity are represented within one SIB, and the increasing values (i.e., values relative to the absolute value) are specified within other SIBs in a concise representation to reduce the overhead amount.

[0121] In other examples, instead of the same number of bits for such parameters, various numbers of bytes are used to represent Px, Py, Pz, Vx, Vy, and Vz. In particular, parameters that are not expected to change significantly from one SIB time point to the next can be represented with fewer bits.

[0122] In yet other examples, the sensitivity of the position and velocity estimation accuracy is considered to determine the magnitudes (i.e., number of bytes) of Px, Py, Pz, Vx, Vy, and Vz. In that case, more bits are used.

[0123] In one embodiment of the present disclosure, one or more of (Px, Py, Pz, Vx, Vy, and Vz) are encoded using a formula such as the following Equation 1 to reduce the number of bits within the SIB.

[0124] [Equation 1] TV = α * IV + β In Equation 1, TV is the true value of the number, and IV is the indicated value specified in the SIB.

[0125] (Px, Py, Pz, Vx, Vy, and Vz)'s prediction ranges are used to determine α and β. In special cases, β is also 0 and thus not used. α and β are either included in the SIB and signaled or pre-defined in the specification.

[0126] In an exemplary manner, when α and β are included in the SIB and signaled, they are not transmitted as frequently compared to IV. Also, α and β are different from each other for the whole (Px, Py, Pz, Vx, Vy, and Vz), or the same α and β can be shared by multiple values.

[0127] In another exemplary manner, one or more tables are defined in the standard to represent the relationship between TV and IV for a given number. IV is also simply an index for the table entry here.

[0128] The information in operations F10S1 and F10S2 is transmitted either fixed or at a configurable period (in that case, the period is specified in the SIB). Such a period is the same as the 160 ms SIB1 period supported by R16, longer, or shorter.

[0129] The platform satellite ephemeris data or position and velocity data specified by the gNB corresponds to the time point when the gNB generates the relevant SIB. In one embodiment of the present disclosure, such data may correspond to a future time point such as the time point when a UE at the cell center receives such an SIB. The UE can recognize such a moment through procedures defined in the specification, or the gNB can provide an instruction for future use through an appropriate SIB.

[0130] In an exemplary manner, the gNB utilizes the real-time platform satellite ephemeris data or position and velocity data and historical data provided by the NTN GW to predict the platform satellite ephemeris data or position and velocity data at a future target time point.

[0131] In one embodiment of the present disclosure, the gNB broadcasts the reference point coordinates of the cell in operation F10S1 or operation F10S2 to enable the UE to estimate the reference point - gNB delay. In other embodiments, the UE determines the relative TA to report using such coordinates. Such information can be used by UEs without timing advance correction capabilities, by UEs without GNSS, and by UEs that temporarily lack GNSS visibility. In other embodiments of the present disclosure, the gNB broadcasts the reference point - gNB delay used by UEs without timing advance correction capabilities, by UEs without GNSS, and by UEs that temporarily lack GNSS visibility. Also, such a delay can be used by the UE to report an increasing TA relative to the TA of the reference point.

[0132] In one embodiment of the present disclosure, the gNB includes a value flag in operation F10S1 or operation F10S2 that indicates whether there is a change in long - term NTN data (e.g., selected elements of the platform satellite ephemeris) or avoids unnecessary SI processing in the UE.

[0133] If comprehensive long - term platform satellite ephemeris data is included in a file (e.g., on the SIM or through an over - the - air (OTA) update) and provided to the UE, in one embodiment of the present disclosure, the current or most recent version number of such a file is broadcast by the gNB, and the UE obtains the more recent ephemeris data (e.g., through application layer signaling).

[0134] If comprehensive long - term platform satellite ephemeris data is included in a file (e.g., on the SIM or through an over - the - air (OTA) update) and provided to the UE, in one embodiment of the present disclosure, time and coordinates are expressed in a simple manner, and the file size can be reduced. For example, the overall time and overall coordinates are specified within a limited number of records in the file, and the increasing time and coordinates are specified within the remaining records in the file.

[0135] Operations F10S1 and F10S2 are related to the platform satellite calendar, and operations F10S3 to F10S9 are related to the management of timing advance (TA).

[0136] In operation F10S3, in an exemplary embodiment of the present disclosure, the gNB transmits to the UE any type of TA report is set for the UE via unicast signaling (e.g., RRC reconfiguration message), broadcast signaling (e.g., SIB processed by all UEs in the cell), or groupcast / multicast signaling (e.g., message processed by a subset of UEs in the cell).

[0137] In one embodiment of the present disclosure, the TA report is either asynchronous or on-demand, in which case the gNB can transmit a PHY indication (e.g., DCI) or a MAC indication (e.g., MAC CE) to the UE and obtain a TA report from the UE.

[0138] In other embodiments of the present disclosure, the TA report is also periodic, in which case the gNB sets a TA reporting period for the UE.

[0139] In still other embodiments of the present disclosure, the TA report is inherent or rule-based, in which case the UE transmits the TA when a TA change (i.e., the difference between the previously reported TA and the currently estimated TA) exceeds a threshold. In such a case, as an exemplary manner, the gNB sets such a threshold for the UE. As another exemplary manner, the threshold is predefined in the specification.

[0140] In one embodiment of the present disclosure, the TA report is complete (i.e., full-type TA), and in other embodiments, an incremental TA is reported.

[0141] In still other embodiments of the present disclosure, TA (complete or increment type) is an index to a table entry, or a formula such as Equation 1 is used, where TV is the TA (complete or increment type) estimated by the UE, and IV is the TA value included in the TA report.

[0142] One or multiple TA reporting methods can be used simultaneously for a given UE. Also, one or more TA reporting methods are mandatory for the assisting UE.

[0143] In operation F10S4, the gNB checks whether to use asynchronous TA reporting. In such a case, operation F10S5 is executed. Otherwise, operation F10S6 is executed.

[0144] In operation F10S5, the gNB determines whether it is asynchronous, whether it is necessary to transmit a command to the UE to obtain TA reporting upon request, or whether it desires transmission. For example, after the last reception of a TA report, if a long time has elapsed, or if it appears that the UL of the UE is not synchronized or has become unsynchronized according to the gNB's judgment, the gNB can request the UE to transmit a TA report via PHY or MAC signaling.

[0145] In operation F10S6, the gNB checks whether a periodic TA report is set for the UE. If not, it proceeds to operation F10S8. If a periodic TA report is set, in operation F10S7, the gNB observes the periodic timer value, and if the timer is about to expire, the gNB waits for a TA report from the UE.

[0146] In operation F10S8, the gNB checks whether a TA report has been received from the UE. If not, the gNB proceeds to operation F10S1. If a TA report has been received, in operation F10S9, the gNB processes the received TA report received from the UE and transmits any necessary TA adjustment value if necessary. Also, if the timer for periodic TA reporting has expired, the timer is restarted in comparison with a new TA report.

[0147] In operation F10S8 of the exemplary embodiment, the gNB can receive from the UE an indication that the UE currently has no GNSS visibility. Such an indication can be specified within the TA report itself in an exemplary manner. In that case, 1 bit indicates the lack of GNSS visibility at the current time. In other ways, one TA report value itself (e.g., all 0s, or all 1s, or any other suitable bit pattern) can indicate the lack of GNSS visibility. The gNB can decide to accommodate a larger time difference between DL and UL (e.g., between (i) UL resource allocation and UL data transmission, and (ii) DL transmission and UL ACK / NACK transmission).

[0148] The TA report itself can be received by the gNB via PHY, MAC, or RRC signaling, or together with UL data in an appropriate header.

[0149] In operation F10S8 of other embodiments of the present disclosure, the gNB receives the lack of a GNSS visibility indication together with PHY signaling (such as UCI), MAC signaling (such as part of a MAC CE), or RRC signaling, or UL data in an appropriate header. Thereafter, the gNB can temporarily allow a longer time margin between DL and UL processing in a specific manner of the implementation example.

[0150] FIG. 11 is a flowchart showing an exemplary UE procedure 1100 for assisting satellite ephemeris and TA management according to an embodiment of the present disclosure. The embodiment of the exemplary UE procedure 1100 for assisting satellite ephemeris and TA management illustrated in FIG. 11 is for illustrative purposes only. FIG. 11 is a specific implementation example related to the exemplary UE procedure 1100 for assisting satellite ephemeris and TA management, and does not limit the scope of the present disclosure.

[0151] In operation F11S1, the UE receives a comprehensive long-term satellite calendar through SIM provisioning or NTN (e.g., through SIB). In an exemplary embodiment of the present disclosure, such data is received by the UE from an application server or an OAM system via a terrestrial network (TN) such as a cellular network or a WiFi network. In other embodiments of the present disclosure, if the comprehensive long-term platform satellite calendar data is included in a file (e.g., via an over-the-air (OTA) update via SIM, TN, or NTN), the time and coordinates are expressed in a simple manner to reduce the file size. For example, the overall time and overall coordinates are specified within a limited number of records in the file, and the increasing time and coordinates are specified within the remaining records in the file.

[0152] In operation F11S2, the UE processes one or more SIBs containing satellite calendar data with relatively long time correlation. Such data may be included in the reference SIB of Release 16 or a new SIB of Release 17 or above. Such SIBs are transmitted at a period known to the UEs within the cell and may be fixed or configurable. In an exemplary embodiment, the UE utilizes the NTN-GW coordinates to estimate the UE-gNBRTD or RTT (see Equation E2 below). In the operation F11S2 of other embodiments, the UE receives the total processing delay between the UE and the gNB and utilizes such delay in Equation E2. The total processing delay includes one or more of the following: platform (e.g., satellite) processing time, NTN GW processing time, gNB processing time, and gNB-NTN-GW transmission delay. The UE may also receive the coordinates of the gNB included in the SIB.

[0153] In operation F11S3, the UE receives data having a relatively short time correlation through system information. Such data may be included in the Release 16 reference SIB or a new SIB of Release 17 or higher. Such SIBs are transmitted at a period known to the UEs within the cell and may be fixed or configurable. In an exemplary embodiment, the UE receives the selected elements of the satellite ephemeris data or the Earth-Centered Earth-Fixed (ECEF) orthogonal position coordinates (Px, Py, and Pz) and optionally the instantaneous velocity (Vx, Vy, and Vz) (derived from the satellite ephemeris data) more frequently when compared with the information referred to in operation F11S2. When applicable, the UE obtains one or more of (Px, Py, Pz, Vx, Vy, and Vz) using a formula defined by a specification such as Formula 1. In other exemplary manners, the UE utilizes one or more tables defined by the standard to represent the relationship between TV and IV for a given number of Formula 1.

[0154] In an exemplary embodiment of the present disclosure, the UE performs a predictive estimation of the current position and / or velocity of the platform taking into account the difference between the time point related to such information and the time point at which such information is used by the UE. For example, the UE can perform linear or non-linear extrapolation to more accurately estimate the position and velocity of the platform at the time when such information is required.

[0155] In one embodiment of the present disclosure, if the gNB broadcasts the reference point coordinates of the cell in operation F11S1 or operation F11S3, the UE utilizes the reference point coordinates to estimate the required reference point - gNB delay. In other embodiments, the UE utilizes the reference point coordinates to determine the relative TA for TA reporting. This information can be used by UEs without timing advance correction capabilities, UEs without GNSS, and UEs that temporarily lack GNSS visibility. In other embodiments of the present disclosure, if the gNB broadcasts the reference point - gNB delay, UEs without timing advance correction capabilities, UEs without GNSS, and UEs that temporarily lack GNSS visibility can utilize such a delay for timing advance correction. Also, such a delay can be used by the UE to report an increasing TA compared to the TA of the reference point.

[0156] In operation F11S2 or operation F11S3, if the gNB includes a value flag indicating the presence or absence of changes in long - term NTN data (e.g., selected elements of the platform satellite ephemeris), the UE utilizes the flag to determine whether to acquire long - term NTN data. For example, if the value flag stored in the UE matches the value flag transmitted by the gNB, the UE already has the longest long - term data and omits SI processing including that long - term NTN data. Conversely, if such a value flag does not match, the UE performs additional system information processing to acquire new long - term NTN data.

[0157] Comprehensive long-term platform satellite ephemeris data is included in a file (e.g., on the SIM or through an over-the-air (OTA) update) and provided to the UE. In one embodiment of the present disclosure, if the current or most recent version number of such a file is broadcast by the gNB, the UE acquires more recent satellite ephemeris data (e.g., through application layer signaling) if the version number associated with the currently stored data does not match the version number broadcast by the gNB.

[0158] In FIG. 11, operations F11S1, F11S2, and F11S3 relate to the platform satellite ephemeris, and operations F11S4 to F11S10 relate to TA management.

[0159] In operation F10S3, according to an exemplary embodiment of the present disclosure, the UE acquires the TA reporting type from the gNB through unicast signaling (e.g., an RRC reconfiguration message), broadcast signaling (e.g., an SIB processed by all gNBs in the cell), or groupcast / multicast signaling (e.g., a message processed by a subset of UEs in the cell).

[0160] In one embodiment of the present disclosure, if the TA reporting is set to be asynchronous or on-demand, the UE expects to receive a PHY indication (e.g., DCI) or a MAC indication (e.g., MAC CE) from the gNB for TA reporting.

[0161] In other embodiments of the present disclosure, if the UE is set for periodic TA reporting, the UE receives the period of the TA reporting.

[0162] In still other embodiments of the present disclosure, the TA report is intrinsic or rules-based, where the UE is expected to transmit the TA when the TA change (i.e., the difference between the previously reported TA and the currently estimated TA) exceeds a threshold. In that case, the UE receives such a threshold from the gNB in an exemplary manner.

[0163] In one embodiment of the present disclosure, the UE stores a TA report type that is (i) an absolute or full TA report, or (ii) an incremental TA report.

[0164] In still other embodiments of the present disclosure, the TA (full or incremental) is an index for a table entry or a formula such as Formula 1 is used, where TV is the TA (full or incremental) estimated by the UE and IV is the TA value included in the TA report.

[0165] One or more TA reporting methods can be used simultaneously for a given UE. Also, one or more TA reporting methods are also mandatory for the assisting UE.

[0166] In operation F11S5, the UE checks whether asynchronous TA reporting is set by the gNB. In such a case, operation F11S6 is executed. Otherwise, operation F11S7 is executed.

[0167] In operation F11S6, the UE checks whether it has transmitted an instruction for asynchronous or requested TA reporting. If the UE has received such an instruction from the gNB, it transmits the TA report to the gNB and moves to operation F11S7.

[0168] In operation F11S7, the UE checks whether periodic TA reporting is set by the gNB. Otherwise, it proceeds to operation F11S9. If it is set, in operation F11S8, the UE observes the periodic timer value, and if the timer expires, the UE transmits the TA report to the gNB, resets the periodic timer, and then proceeds to F11S9.

[0169] In operation F11S9, according to an exemplary embodiment of the present disclosure, the GNSS-capable UE checks the availability of gNSS. If it is not available, the UE proceeds to operation F11S10. Otherwise, the UE proceeds to operation F11S11.

[0170] In operation F11S10, after the UE transmits a "GNSS unavailable" indication to the gNB, it proceeds to operation F11S11.

[0171] In operation F11S11, the UE checks whether the gNB has transmitted a TA command. If not, the UE proceeds to operation F11S1. If the gNB has transmitted a TA command, the UE performs an adjustment to the UL timing considering the TA command and then proceeds to operation F11S1.

[0172] In FIG. 11, the UE transmits a TA report to the gNB via PHY, MAC, or RRC signaling or together with the UL data in the appropriate header.

[0173] FIG. 12 illustrates a proposed structure 1200 that supports the management of NTN time, satellite ephemeris, and other aspects according to an embodiment of the present disclosure. The embodiment of the proposed structure 1200 shown in FIG. 12 for supporting the management of NTN time, satellite ephemeris, and other aspects is for illustrative purposes only. FIG. 12 is a specific implementation example related to the proposed structure 1200 for supporting the management of NTN time, satellite ephemeris, and other aspects and does not limit the scope of the present disclosure.

[0174] The structure shown in FIG. 12 is suitable for a transparent payload and an integrated gNB. The integrated gNB combines the functions of a gNB-DU (gNB-distributed unit) and a gNB-CU (gNB-central unit).

[0175] The UE can use one of one or more network functions and access networks to provide short-term and long-term NTN data (e.g., cellular access or WiFi access or TN using NTN).

[0176] In Figure 12, the network platform (NP) is an NTN entity that orbits the Earth (e.g., a satellite) or is in flight (e.g., HAPS). The network infrastructure (NI) is composed of an NTN platform and an NTN GW. The NTN infrastructure controller (NIC) is a controller specific to the implementation for the NTN infrastructure (e.g., satellite / HAPS and NTN GW). This is a substitute for the NI and interfaces with conventional 5G network functions (NFs). It exchanges information with appropriate 5G NFs and delay-insensitive information. For example, the NIC provides the IP address and (latitude, longitude) position of the NTN GW to the gNB or gNB-NTN. The NIC obtains information related to the platform through the NTN GW. The application server (AS) provides long-term NTN data such as a long-term satellite calendar to the UE via a wired or wireless connection to the NTN UE. For example, such data can be stored on the USIM (universal subscriber identity module) or the memory of the UE if appropriate. The gNB-NTN is a logical functional option inside the gNB that interfaces with the NI for signaling related to the NI. For example, the gNB-NTN exchanges real-time or near-real-time NTN data such as the (position, velocity, and time) vector of the satellite with the NTN-GW. Also, the gNB-NTN exchanges long-term data such as the selected orbit parameters and information related to the NTN-GW specification or processing with the NTN-GW or NIC. The NTN-GW specification includes whether there is a change in the (P, V, T) parameters provided by the platform.

[0177] The NTN-GW has two connections with the gNB or gNB-NTN: (i) a control plane connection for exchanging signaling messages such as gNB and NTN-GW processing specifications (e.g., initial (P, V, T) data) and (P, V, T) parameters, and (ii) the NR-Uu waveform received within the cell from all NTN UEs or transmitted within the cell.

[0178] The eNTN-GW implements the conventional NTN-GW function and supports the NR baseband signal instead of the NRRF signal. A protocol such as eCPRI can be used between the gNB and the eNTN-GW for increased stability by leveraging a wired interface of an optical fiber infrastructure instead of a wireless interface.

[0179] The CP signaling and the transmission of NR-specific signals (e.g., RF or baseband signals) between the NTN-GW (or eNTN-GW) and the gNB (or gNB-NTN) are initially implementation-specific (i.e., beyond the scope of 3GPP®) and can be opened for future by industry interest.

[0180] The feeder link has two connections between the platform and the gNB, or gNB-NTN: (i) a control plane connection for exchanging signaling messages including (P, V, T) parameters, and (ii) the NR-Uu waveform received within the cell from all UEs or transmitted within the cell.

[0181] Generally, the following connections can also be wired connections (e.g., optical fibers within an IP network or a metro Ethernet network) or wireless connections (e.g., using a microwave parabolic antenna): (i) Nnic-ntn-gw, (ii) NgNB-nic, (iii) NgNB-ntn-gw, (iv) Nnic-mgmt.

[0182] The gNB-DU may or may not be located in the same place as the NTN-GW / eNTN-GW.

[0183] Figure 13 illustrates a proposed structure 1300 that aids in the management of NTN time, satellite ephemeris, and other aspects according to an embodiment of the present disclosure. The embodiment of the proposed structure 1300 illustrated in Figure 13, which aids in the management of NTN time, satellite ephemeris, and other aspects, is for illustrative purposes only. Figure 13 is a specific exemplification related to the proposed structure 1300 that aids in the management of NTN time, satellite ephemeris, and other aspects and does not limit the scope of the present disclosure.

[0184] The structure illustrated in Figure 13 is suitable for a transparent payload and a split gNB. The split gNB has two respective entities, the gNB-DU and the gNB-CU.

[0185] In an exemplary embodiment of the present disclosure, information regarding the transmission power of the NTN platform and the reception power (e.g., reception sensitivity) of the NTN platform is communicated to the gNB by an entity. The entity can also be an NTN platform, an NTN-GW, an NTN controller, an OAM, or an application server. As an exemplary approach, since the power transmitted by the platform can be used by the gNB, the gNB knows what to broadcast through the SIB.

[0186] In an embodiment of the present disclosure, when the gNB broadcasts satellite ephemeris data for the serving cell and neighboring cells, in order to reduce signaling overhead, instead of replicating the same satellite ephemeris for multiple cells, only the explicit satellite ephemeris data is included. For example, if multiple cells belong to the same satellite, the satellite ephemeris data related to that satellite is not repeated for all such cells.

[0187] In one embodiment of the present disclosure, the UE uses the time delay related information broadcast by the gNB to facilitate its own operation in the following cases: (i) when the UE has GNSS capabilities but may not have an accurate or reliable GNSS-based position at present (e.g., due to poor GNSS visibility), (ii) when the UE has GNSS capabilities but may not have pre-compensation capabilities, and (iii) when the UE may not have GNSS capabilities.

[0188] In one embodiment of the present disclosure, in the cases identified above, the UE utilizes the delay information broadcast by the gNB to determine the settings of timers in various protocol layers such as Drx-HARQ-RTT-TimerUL, drx-HARQ-RTT-TimerDL, ra-ResponseWindow, ra-ContentionResolutionTimer, and sr-ProhibitTimer. When the UE has stable / accurate knowledge of the UE-gNB delay specific to the UE, the UE can add an offset when such a timer starts or when the existing timer value (e.g., defined up to Release 16) increases by the amount of the UE-gNB delay (both approaches are equivalent). In an exemplary embodiment of the present disclosure, a UE without a stable GNSS-based own position estimates the UE-gNB delay using the delay information broadcast by the gNB for the three cases described above. Details regarding the "delay information" are given below.

[0189] As one approach, the delay information includes the gNB estimated gNB-to-reference point delay, where the reference point delay may correspond to the delay between the gNB and the average position (e.g., cell center). By another approach, the reference point corresponds to an in-cell position with the minimum propagation delay. The one-way delay or round-trip delay is specified by the gNB.

[0190] With an exemplary approach, the delay includes only the propagation delay. With other approaches, the delay is the total delay including one or more of the processing delay (e.g., NTN platform processing and NTN-GW processing) and the transmission delay (e.g., NTN-GW-gNB transmission delay). In an exemplary embodiment of the present disclosure, the gNB can indicate the type of delay being broadcast.

[0191] With yet other approaches, the delay is split into multiple components such as service link delay, feeder link delay, and (optionally) other miscellaneous delays (e.g., processing + transmission delay). In such cases, a UE without an accurate / reliable GNSS-based position can estimate the service link delay using the explicit service link delay (when broadcast by the gNB) or the coordinates of a reference point (e.g., cell center or the point associated with the minimum delay). The feeder link delay can be explicitly broadcast or the gNB can broadcast the NTN-GW coordinates.

[0192] In an exemplary embodiment of the present disclosure, the gNB broadcasts its own coordinates to enable the UE to estimate the feeder link delay.

[0193] In an exemplary embodiment of the present disclosure, when the position of the UE's GNSS base is unavailable but the time at the UE is still accurate, the UE can estimate the UE-gNB delay by subtracting the transmission time of the SI broadcast by the gNB from the reception time of the relevant SI.

[0194] In an exemplary embodiment of the present disclosure, when reporting its position to the network, the UE indicates the reliability of the position accuracy quantitatively or qualitatively. For example, the UE can indicate that the gNSS is not currently visible. The UE can indicate that its position corresponds to the last known GNSS-based position.

[0195] In one embodiment of the present disclosure, when the UE has an accurate / reliable GNSS-based position available to the UE, the UE calculates the total delay between the UE and the gNB as follows.

[0196] [Equation E1] UE-gNB Total Delay (total delay) = "UE-specific UE-platform propagation delay (propagation delay)" + "Common (common) platform-NTN-GW propagation delay (propagation delay)" + "Total Processing Delay (total processing delay)"

[0197] In Equation E1, the UE-specific UE-platform propagation delay is estimated by the UE based on the coordinates of the platform broadcast by the gNB through SI and the position of its own GNSS-based. As an exemplary approach, the distance I between the UE and the platform is divided by the speed of light (i.e., 3x10 8 m / s) to determine the propagation delay between the UE and the platform.

[0198] In Equation E1, the "Common (common) platform-NTN-GW propagation delay" (also referred to as the "feeder link delay") can be broadcast by the gNB through SI by an exemplary approach. As another approach, the NTN-GW coordinates (or gNB coordinates as a substitute) and the platform coordinates are used to determine the propagation delay between the platform and the NTN-GW instead of the feeder link delay that varies over time.

[0199] In Equation E1, the "Total Processing Delay (total processing delay)" is the sum of the following: (i) The combination of two or more of the minimum or normal processing delays at the platform, NTN-GW, and gNB, and (ii) Can a part of the minimum performance specification be specified as a basic premise, or the NTN-GW-gNB transmission delay broadcast by the gNB through SI?

[0200] The round-trip time (RTT) between the UE and the gNB can be estimated by the UE (assuming symmetry) as follows.

[0201] [Equation E2] UE-gNBRTT = 2 * UE-gNB Total Delay (total delay)

[0202] In other embodiments of the present disclosure, if the UE does not have pre-correction ability, or the GNSS is currently unavailable (or after the Xms threshold time has elapsed after the accurate GNSS base position becomes available), or if the UE does not have GNSS ability, the UE can estimate the UE-gNB total delay using the following Equation E3.

[0203] [Equation E3]

[0204] UE-gNB Total Delay (total delay) = “Common Reference Point - platform propagation delay” + “Common platform - NTN-GW propagation delay” + “Total Processing Delay”

[0205] In Equation E3, “Common Reference Point - platform propagation delay” is the propagation delay between the common reference point (e.g., the center of the serving cell or other appropriate point on the geographical area irradiated by the cell beam) and the platform.

[0206] In an exemplary approach, “Total Processing Delay” can be set to 0 in Equation E3.

[0207] Additional Embodiments for TA Reports

[0208] In one embodiment of the present disclosure, the UE transmits the TA through the MAC CE in the random access procedure based on whether such a report is enabled (possible) or disabled (not possible) by the gNB in the SIB in operation F9S6. For example, the gNB identifies the indicator taReportingEnabled in the SIB (e.g., SIB1, non-SIB2, or a new NTN SIB). If this indicator is 1 (or 0), the UE reports the TA through the MAC CE in the RA procedure. According to another exemplary approach, taReporting is not explicitly included in the SIB, and its existence means that the UE must transmit the TA report to the gNB in the RA procedure.

[0209] In other embodiments of the present disclosure, when the UE receives the TA reporting setting through RRC signaling, such a setting (including whether the TA reporting is enabled or disabled) replaces the TA reporting indicator received by the UE through the SIB.

[0210] In other embodiments of the present disclosure, when the UE moves to a new cell in any RRC state (e.g., by cell reselection or handover), the UE uses the TA reporting setting including the enable / disable for such an indicator when the TA reporting feedback indicator is received inherently (e.g., through the existence of the IE) or explicitly. If such an indicator is not received for the new cell through dedicated RRC signaling, the UE uses the indicator obtained through the SIB.

[0211] In one embodiment of the present disclosure, the TA report setting is specified by the gNB through an SIB (e.g., an SIB improved for NTN or a new NTN SIB) in operation F9S6, and it will save radio resources related to the specification of the TA report setting through dedicated signaling to many UEs in operation F9S10.

[0212] In one embodiment of the present disclosure, the UE considers the priority of such a MAC CE in order to determine whether to transmit a MAC CE including a TA report (e.g., through msgA or msg3 / msg5) during the RA procedure. As an exemplary approach, if the UE cannot transmit the MAC CE through msgA, msg3, or msg5, the UE transmits the MAC CE at the first opportunity when appropriate uplink resources are available for transmitting the MAC CE including the TA report.

[0213] In other embodiments of the present disclosure, the MAC CE including the TA report is given a higher priority than the MAC CE including the power headroom report. As another approach, the MAC CE including the TA report is given a lower priority than the MAC CE including the power headroom report.

[0214] According to still another approach, the MAC CE including the TA report and the MAC CE including the power headroom report are given equal priorities, and the UE selects whether to transmit any MAC CE to the gNB. According to another exemplary approach, the UE gives priority to transmitting the MAC CE including the power headroom report over the TA report MAC CE when its own power headroom is less than a threshold (e.g., phrReportingThreshold).

[0215] In other embodiments of the present disclosure, the conventional cell reselection method is not suitable for NTNs having different types of beams, which is due to, in particular, satellite movement and the fact that the RSRPs of the serving cell and adjacent cells are very similar. Therefore, a new approach is needed for NTNs to improve the stability of cell reselection.

[0216] FIG. 14 illustrates an example related to the operation of a flexible cell reselection system 1400 according to an embodiment of the present disclosure. The embodiment of the operation of the flexible cell reselection system 1400 illustrated in FIG. 14 is for illustrative purposes only. FIG. 14 is a specific implementation example of the operation of the flexible cell reselection system 1400 and does not limit the scope of the present disclosure.

[0217] As illustrated in FIG. 14, the gNB receives information such as NTN / beam type and candidate trigger, and transmits information related to the selected trigger, the combination of the selected triggers, the search criteria, and the beam type.

[0218] FIG. 15 illustrates an example of an operation 1500 for the implementation of flexible QoS according to an embodiment of the present disclosure. The embodiment of the operation 1500 for the implementation of flexible QoS illustrated in FIG. 15 is for illustrative purposes only. FIG. 15 is a specific implementation example related to the operation 1500 for the implementation of flexible QoS and does not limit the scope of the present disclosure.

[0219] As illustrated in FIG. 15, the eNB / gNB identifies the NTN / beam type and available cell reselection triggers. The eNB / gNB selects a specific trigger and determines one or more trigger combinations. The eNB / gNB broadcasts the NTN / type and trigger combination. The UE avoids measurements for power saving if applicable. The UE evaluates the trigger combination and performs cell reselection if appropriate conditions are satisfied.

[0220] Figure 16 illustrates an example of a general UE-network procedure 1600 for the NTN flexible cell reselection system according to an embodiment of the present disclosure. The embodiment of the general UE-network procedure 1600 for the NTN flexible cell reselection system illustrated in Figure 16 is for illustrative purposes only. Figure 16 is a specific implementation example of the general UE-network procedure 1600 for the NTN flexible cell reselection system and does not limit the scope of the present disclosure.

[0221] In operation F16S1, the gNB / eNB obtains a configuration including beam types for each cell. According to one processing method, the beam types are classified into the following three types of beam types: Earth-fixed, quasi-Earth-fixed (also referred to as steerable beam), and Earth-moving (i.e., fixed non-steerable beam). For example, a satellite in a geostationary orbit has an Earth-fixed beam that always covers the same geographical area. Satellites in non-geostationary orbits (e.g., LEO and MEO) can have Earth-Moving beams that continuously move and cover different geographical areas at different times based on continuity. Satellites in non-geostationary orbits can have quasi-Earth-fixed beams that cover a given geographical area for a certain period of time and different geographical areas at different times.

[0222] In operation F16S2, in an exemplary embodiment of the present disclosure, the gNB / eNB transmits one or more parameters through system information so that the UE can save some processing power and enable strong cell reselection. As an exemplary approach, in operation F16S2, the gNB / eNB transmits one or more of Disable-s-IntraSearchP, neighborSearchTimerCellReselection, and parameters related to the combined trigger that aids cell reselection. In an exemplary implementation, disable-s-IntraSearchP indicates the case where the UE has to use or ignore the broadcast value of s-IntraSearchP to determine the necessity of performing measurements on neighboring cells. As another approach, disable-s-IntraSearchP indicates whether the UE has to use the broadcast values of s-IntraSearchP and IntraSearchQ to determine the necessity of performing measurements on neighboring cells. In one implementation, the timer neighborSearchTimerCellReselection indicates the period during which the UE can skip measurements of neighboring cells to save processing power and extend battery life. For example, when the beam type is uasi-Earth-Fixed in a given NTN, the gNB / eNB transmits disable-s-IntraSearchP and neighborSearchTimerCellReselection, which are parameters that (i) enable the UE to detect neighbors even when the serving cell RSRP is strong, and (ii) avoid measurements of neighboring cells to save battery life after cell reselection is performed. In an exemplary implementation, the gNB / eNB enables the UE to evaluate cell reselection trigger conditions by implicitly or explicitly specifying a combined trigger. For details of the combined trigger, reference may be made to the content related to FIG. 19.

[0223] As another approach, so that the UE skips measurements, "S" rxlev > S IntraSerachP and S qual > S IntraSerachQWhen the condition of "」 is not satisfied, and thus the serving cell signal measurement value (e.g., RSRP) is not good, by selecting an appropriate value of s-IntraSearchP (e.g., a high value of s-IntraSearchP) within the specified range that is specified to search for neighbors, a disable effect can be obtained. When the UE is "S" from the perspective of s-IntraSearchQ rxlev > S IntraSerachP and S qual > S IntraSerachQ To ensure that the condition of "」 is not satisfied, s-IntraSearchQ may not exist in the system information in a single approach manner, and only s-IntraSearchP becomes the only determining factor for the condition. As another approach, an appropriate value of s-IntraSearchQ (e.g., a high value of s-IntraSearchQ) within the specified range can be selected.

[0224] In operation F16S3, the UE determines when to perform cell reselection that must perform measurements of neighboring cells using received parameters such as parameters related to Disable-s-IntraSearchP, neighborSearchTimerCellReselection, and combined triggers.

[0225] FIG. 17 illustrates an example of a general UE-network procedure 1700 for the NTN flexible cell reselection system according to an embodiment of the present disclosure. The embodiment of the general UE-network procedure 1700 for the NTN flexible cell reselection system illustrated in FIG. 17 is for illustrative purposes only. FIG. 17 is a specific implementation example of the general UE-network procedure 1700 for the NTN flexible cell reselection system and does not limit the scope of the present disclosure.

[0226] In operation F17S1 (identical to operation F16S1), the gNB / eNB obtains its configuration including the beam type for each of its cells. By one processing method, the beam type is classified into the following three types of beam types: Earth-fixed, quasi-Earth-fixed (also referred to as a steerable beam), and Earth-moving (i.e., a fixed non-steerable beam). For example, a satellite in a geostationary orbit has an Earth-fixed beam that always covers the same geographical area. Satellites in non-geostationary orbits (e.g., LEO and MEO) can have Earth-Moving beams that continuously move and cover different geographical areas at different times based on continuity. Satellites in non-geostationary orbits can have quasi-Earth-fixed beams that cover a given geographical area for a certain period of time and cover other geographical areas at different times.

[0227] In operation F17S2, according to an exemplary embodiment of the present disclosure, the gNB / eNB transmits disable-s-IntraSearchP when necessary (e.g., when the beam type is quasi-Earth-Fixed in a given NTN). In an exemplary implementation, the gNB / eNB can carry its parameter on SIB2 that normally transmits s-IntraSearchP and transmit it. In other implementations, the gNB / eNB transmits disable-s-IntraSearchP through an SIB other than SIB2. For example, a new SIB defined for NTN can transmit disable-s-IntraSearchP.

[0228] In operation F17S3, the gNB / eNB transmits parameters related to the combined trigger that assists cell reselection and (if necessary) neighborSearchTimerCellReselection through a new SIB that can be specifically defined for NTN. In an exemplary embodiment, the gNB / eNB transmits neighborSearchTimerCellReselection when the beam type is quasi-Earth-Fixed within a given NTN. In an exemplary embodiment, the gNB / eNB enables the UE to evaluate cell reselection trigger conditions by implicitly or explicitly identifying the combined trigger. For details of the combined trigger, reference may be made to the content related to FIG. 19.

[0229] In operation F17S4, which is the same as operation F16S3, the UE determines when to perform cell reselection and whether it must perform measurements of neighboring cells using received parameters such as Disable-s-IntraSearchP, neighborSearchTimerCellReselection, and parameters related to the combined trigger.

[0230] FIG. 18 illustrates an exemplary UE procedure 1800 for the flexible cell reselection system of NTN according to an embodiment of the present disclosure. The embodiment of the UE procedure 1800 for the flexible cell reselection system of NTN illustrated in FIG. 18 is for illustrative purposes only. FIG. 18 is a specific embodiment of the UE procedure 1800 for the flexible cell reselection system of NTN and does not limit the scope of the present disclosure.

[0231] In operation F18S1 (identical to operations F16S1 and F17S1), the gNB / eNB obtains a configuration including beam types for each cell. By one processing method, the beam types are classified into the following three types of beam types: Earth-fixed, quasi-Earth-fixed (also referred to as steerable beam), and Earth-moving (i.e., fixed non-steerable beam). For example, a satellite in geostationary orbit has an Earth-fixed beam that always covers the same geographical area. Satellites in non-geostationary orbits (e.g., LEO and MEO) can have Earth-Moving beams that continuously move and cover different geographical areas at different times based on continuity. Satellites in non-geostationary orbits can have quasi-Earth-fixed beams that cover a given geographical area for a certain period of time and cover other geographical areas at different times.

[0232] In operation F18S2 (similar to operation F16S2 in FIG. 16 or a combination of operations F17S2 and F17S3 in FIG. 17), in an exemplary embodiment of the present disclosure, the gNB / eNB transmits one or more parameters through system information in order for the UE to save some processing power and enable strong cell reselection. As an exemplary approach, in operation F18S2, the gNB / eNB transmits one or more of Disable-s-IntraSearchP, neighborSearchTimerCellReselection, and parameters related to the combined trigger that supports cell reselection. For the detailed content of the combined trigger, reference can be made to the content related to FIG. 19.

[0233] In operation F18S3, the UE searches for neighbors and determines the need to perform measurements on neighboring cells. In an exemplary embodiment, the UE processes normal parameters such as s-IntraSearchP and s-IntraSearchQ in the system information (e.g., SIB2) and new parameters defined in this disclosure such as disable-s-IntraSearchP and neighborSearchTimerCellReselection to determine whether to search for neighboring cells.

[0234] In operation F18S3 of an exemplary embodiment, if the gNB has disable-s-IntraSearchP and neighborSearchTimerCellReselection specified in the system information, the UE starts or restarts the timer after cell reselection is performed. Also, while the timer value is less than neighborSearchTimerCellReselection, the UE skips the neighboring cell search and avoids measuring neighboring cells. By an exemplary approach, when such a timer is not running, the UE ignores the value of s-IntraSearchP based on the parameter disable-s-IntraSearchP and searches for neighboring cells. Then, the UE can detect the input NTN cell and perform cell reselection when appropriate conditions are met.

[0235] In operation F18S4, when the UE is searching for neighboring cells and performing measurements on neighboring cells, the UE evaluates one or more trigger conditions and, if one or more of the trigger conditions are satisfied, performs cell reselection.

[0236] Figure 19 illustrates an exemplary network procedure 1900 for a flexible cell reselection system within NTN according to an embodiment of the present disclosure. The embodiment of the network procedure 1900 for the flexible cell reselection system of NTN illustrated in Figure 19 is for illustrative purposes only. Figure 19 is a specific implementation example of the network procedure 1900 for the flexible cell reselection system of NTN and does not limit the scope of the present disclosure.

[0237] In operation F19S1, according to an embodiment of the present disclosure, the gNB / eNB makes a decision regarding a specific trigger combination. Also, the gNB / eNB determines what conditions must be used by the UE to evaluate the need for cell reselection. One given condition utilizes one specific combination of triggers.

[0238] In operation F19S2, according to an exemplary embodiment of the present disclosure, the gNB specifies one or more of the following through system information: (i) the number N of trigger conditions (e.g., N = 2), (ii) the identifier of the combined trigger for each trigger condition (e.g., the combined trigger that combines individual triggers for the time since the last cell reselection (TSLCR) and the neighbor cell signal measurement (NCSM)) and the method of combining the individual triggers of the combined trigger (e.g., a logical function such as a logical AND function or a logical OR function), and (iii) the neighbor cell selection method (e.g., rank-based or non-rank-based). Details regarding the trigger combination and the trigger ring conditions are given below after the description of F19S3.

[0239] As an exemplary approach, the gNB / eNB can define two trigger conditions (i.e., N = 2) related to the quasi-Earth-Fixed beams - trigger condition 1 and trigger condition 2. To define trigger condition 1, the gNB specifies the TSLCR and NCSM as individual triggers, specifies the logical OR function, and combines the TSLCR and NCSM. To define trigger condition 2, the gNB specifies the Neighboring Serving Cell Signal Measurement (NSCSM) not only as an individual trigger but also as a trigger combination (thus, any logical combination function is not required in this example). Here, the described exemplary approach can be extended to any appropriate number of trigger conditions and any appropriate number of individual triggers related to a given trigger combination. Also, for the neighboring cell-based individual trigger (which is part of the combined trigger), an offset of the satellite mobile base can be applied by the gNB / eNB decision.

[0240] As another exemplary approach, the set of all conditions (along with the related combination of triggers) is defined together in the specification, and the gNB / eNB indicates, during cell reselection execution, through the system information, which of such conditions (e.g., condition 1 and 3 out of a set of 5 conditions) are to be used by the UE.

[0241] As yet another exemplary approach, the set of all trigger conditions (along with the related combination of triggers) is defined together in the specification, and the availability of a given trigger condition is defined in the specification (e.g., conditions 1 and 3 are applicable for Earth-fixed beams). In that case, as an exemplary approach, the gNB / eNB indicates the "beam type" through the system information. Thereby, the UE utilizes the applicable conditions based on the beam type.

[0242] In other approach methods, trigger conditions applicable to GNSS-capable UEs and non-GNSS-capable UEs are identified, and the UE becomes capable of evaluating relevant trigger conditions based on its GNSS capability. For one or more relevant trigger conditions, the availability of GNSS capability of such UEs can be explicitly specified in the specification or identified by the gNB / eNB in the system information through an appropriate indicator or flag for the given trigger condition.

[0243] In operation F19S3, the UE performs measurements on the amount specified by the trigger and evaluates the available conditions for using one or more combined triggers. The UE performs cell reselection when any one of the conditions is satisfied.

[0244] Individual triggers and trigger combinations

[0245] Different trigger amounts are suitable for different types of beams. Individual triggers and trigger combinations related to cell reselection in NTN are specified below.

[0246] One-way propagation delay (OPDSC) to a serving cell as a trigger. The one-way propagation delay (OPD) between an NTN platform (e.g., a satellite or HAPS) and a UE can be used as an indirect indicator related to the distance between the NTN platform and the UE. If the OPD is greater than that of the serving cell (e.g., in the case of a fixed-Earth beam), the UE is near the boundary of the serving cell. A large OPD indicates the need for cell reselection (e.g., in the case of a fixed-Earth beam). For example, "if (OPDSC > Threshold_PropagationDelayServingCell_CellReselection)" can be used as part of one combined trigger condition. The UE can estimate the gNB-to-UE delay by observing the time difference between the time when the SIB containing the timestamp is received by the UE and the time when the SIB containing the timestamp is generated by the gNB. Then, the UE can calculate the OPDSC by subtracting the gNB-to-the-platform delay (e.g., the total feeder link delay) from the gNB-to-UE delay. OPDSC can function as a useful trigger for both Earth-fixed and Earth-moving beams. The gNB / eNB broadcasts Threshold_PropagationDelayServingCell_CellReselection through system information in an exemplary embodiment of the present disclosure.

[0247] As a trigger, the distance between the UE and a given cell (i.e., the serving cell or an adjacent cell) is defined as the distance between the UE and the cell center, and such a cell center is a reference point within the center of the beam coverage area of the serving cell and the adjacent cell.

[0248] As one trigger, the distance to the platform within the serving cell (DTPSC). The distance between the NTN platform and the UE within the serving cell can be used as a trigger. If the DTPSC is large, the UE is near the boundary of the serving cell. A large distance indicates the need for cell reselection (e.g., in the case of the fixed-Earth beam case). For example, "if(DTPSC>Threshold_Distance_ServingCell_CellReselection)" can be used as part of one combined trigger condition. A GNSS-capable UE can estimate the distance to the platform using the GNSS position of the platform's GNSS position received through system information. That distance can function as a useful trigger for Earth-fixed beams. The gNB / eNB broadcasts Threshold_Distance_ServingCell_CellReselection through system information in an exemplary embodiment of the present disclosure.

[0249] As one trigger, the time after the last cell reselection (TSLCR). After the last cell reselection, the elapsed time can be used as a trigger (e.g., in the case of the quasi-Earth-Fixed beam). For example, "if(TSLCR>Threshold_Time_CellReselection)" can be used as part of one combined trigger condition. The UE starts or restarts the TSLCR when performing cell reselection for a new cell. The gNB / eNB broadcasts Threshold_Time_CellReselection through system information in an exemplary embodiment of the present disclosure.

[0250] The TSLCR approach corresponds to a method expressed by the serving time or residence time of a cell in a given geographical area in the case of a quasi-Earth-Fixed beam (i.e., a fixed beam for LEO). Using an absolute time stamp as a trigger is a further approach corresponding to the TSLCR approach.

[0251] The serving cell elevation angle (SCEA) as a trigger. The elevation angle of the serving cell can be used as a trigger for cell reselection. A large SCEA means that the UE is near the serving cell boundary, thereby indicating the need for cell reselection. For example, "if (SCEA > Threshold_ServingElevationAngle_NTN)" can be used as part of a combined trigger condition. In such an expression, when the satellite of the NTN cell is directly overhead, the elevation angle is 90°, and it increases as the NTN cell or beam continues to move away from the UE. The gNB / eNB broadcasts Threshold_ServingElevationAngle_NTN through system information in the exemplary embodiments of the present disclosure. The gNB / eNB broadcasts Threshold_ServingElevationAngle_NTN through system information in the exemplary embodiments of the present disclosure.

[0252] Neighbor Cell Elevation Angle (NCEA) as a trigger. The elevation angle of a neighboring cell can be used as a trigger for cell reselection. A large NCEA means that the UE is near the boundary of the neighboring cell it is facing, thereby indicating the need for cell reselection. For example, "if (NCEA > Threshold_NeighborElevationAngle_NTN)" can be used as part of a combined trigger in the trigger condition. In such an expression, when the satellite of the NTN cell is directly overhead, the elevation angle is 90°, and it increases as the NTN cell or beam continues to move away from the UE. The gNB / eNB broadcasts Threshold_NeighborElevationAngle_NTN through system information in the exemplary embodiments of the present disclosure.

[0253] Absolute Signal Measurement Difference (ASMD) as a trigger. The absolute difference in signal measurement values between the serving cell and a neighboring cell can be utilized as a trigger for cell reselection. A small ASMD means that the UE is near the boundary of the neighboring cell and the serving cell it is facing, thereby indicating the need for cell reselection. For example, "if (ASMD < Threshold_AbsoluteDifference_ServingNeighbor_NTN) for timeToTrigger" can be used as part of a combined trigger in the trigger condition. timeToTrigger can be set to 0. Exemplary signal measurement values include RSRP, RSRQ, and SINR. The gNB / eNB broadcasts Threshold_AbsoluteDifference_ServingNeighbor_NTN through system information in the exemplary embodiments of the present disclosure.

[0254] Neighbor Cell Signal Measurement (NCSM) as a trigger. The neighbor cell signal measurement can be used as a trigger for cell reselection. A strong NCSM means that the UE has a satisfactory radio environment with the neighbor cell. For example, "if (NCSM > Threshold_SignalMesurement_Neighbor_NTN) for timeToTrigger" can be used as part of a combined trigger condition. timeToTrigger can be set to 0. Exemplary signal measurements include RSRP, RSRQ, and SINR. The gNB / eNB broadcasts Threshold_SignalMesurement_Neighbor_NTN through system information in the exemplary embodiments of the present disclosure.

[0255] Neighbor and Serving Cell Signal Measurement (NSCSM) as a trigger. Both the neighbor cell signal measurement (NCSM) and the serving cell signal measurement (SCSM) can be used as part of a trigger for cell reselection. A combination of strong NSM and weak SCM means that the UE has a better radio channel environment with the neighbor cell than with the serving cell, and thus cell reselection is desirable. For example, "if ((NCSM - SCSM) > Threshold_SignalMesurement_Serving_Neighbor_NTN) for timeToTrigger" can be used as part of a combined trigger condition. Exemplary signal measurements include RSRP, RSRQ, and SINR. The gNB / eNB broadcasts Threshold_SignalMesurement_Serving_Neighbor_NTN through system information in the exemplary embodiments of the present disclosure.

[0256] Improvement of individual neighbor cell triggers

[0257] In an exemplary embodiment of the present disclosure, an offset based on satellite movement may be added to the non-signal measurement adjacent cell trigger quantities (e.g., elevation angle, distance, and propagation delay) described above so as to recommend or prevent cell reselection for a given adjacent cell. For example, a positive offset may be used to encourage cell reselection for an incoming adjacent cell for a given adjacent cell. A zero offset neither recommends nor prevents cell reselection for an adjacent cell. A negative offset may be used to prevent cell reselection for an outgoing adjacent cell for a given adjacent cell.

[0258] Depending on the position of the offset in the mathematical formula defining the trigger condition, the offset may be reversed. For example, a positive offset may be used to prevent cell reselection for an adjacent cell without recommending it.

[0259] In other possible embodiments, the UE may be prohibited from evaluating adjacent cells that are not present in the adjacent list for cell reselection and handover purposes in order to prevent cell reselection for adjacent cells not specified in the adjacent list. According to an exemplary approach, the self organizing network (SON) function and the drive test minimization (MDT) can continue to search for and measure adjacent cells that are not listed in the adjacent list.

[0260] According to an exemplary approach, the basic trigger "if(triggerQuantityForANeighbor>Threshold_TriggerQuantity)" may be modified to "if((triggerQuantityForANeighbor+Δ)>Threshold_TriggerQuantity)" to reflect the satellite movement based offset Δ. According to an exemplary approach, in a given cell, the gNB / eNB broadcasts the Δ value for the target adjacent cell.

[0261] In a specific example, the basic trigger "if (NCEA > Threshold_NeighborElevationAngle_NTN)" can be modified to "if ((NCEA + Δ) > Threshold_NeighborElevationAngle_NTN)", which is part of the combined trigger within the trigger condition, to reflect the offset Δ of the satellite mobile base station.

[0262] In an exemplary embodiment, when the UE performs a search for an adjacent cell not mentioned in the system information, as an exemplary approach, a basic offset (e.g., a negative offset) can be defined and broadcast by the gNB / eNB to prevent cell reselection for such adjacent cells. In other embodiments, the basic value can be explicitly defined in the specification.

[0263] Combined Trigger and Trigger Condition

[0264] In the terrestrial network (TN), RSRP and RSRQ based cell reselection are commonly used. However, in NTN, signal measurement values such as RSRP are similar for both the serving cell and adjacent cells. Therefore, a number of triggers including those specific to NTN are combined to improve the stability of the cell reselection procedure.

[0265] In one embodiment of the present disclosure, partial triggers (i.e., individual triggers) of a previously defined individual quantity base are combined in a flexible manner to generate a number of combined triggers for a given trigger condition.

[0266] In one embodiment of the present disclosure, the individual triggers "OPDSC Trigger" and "NCSM Trigger" are combined using a logical AND function as follows to generate a combined trigger ("Trigger A").

[0267] For one of the neighboring cells, ["If(OPDSC>Threshold_PropagationDelayServingCell_CellReselection)"] AND

[0268] ["If((NSM + Δ)>Threshold_SignalMesurement_Neighbor_NTN) for timeToTrigger"], if so, cell reselection is triggered and the neighboring cell selection procedure is executed.

[0269] Such a combined trigger "A" is suitable for the terrestrial mobile beam. The use of the neighboring list of the satellite mobile base prevents inaccurate cell reselection (i.e., cell reselection for a neighboring cell that is moving far away from the UE).

[0270] The first part of the combined trigger "A" indicates that the UE is far from the center of the serving cell and close to the boundary of the serving cell, indicating the need for cell reselection. The second part of the combined trigger indicates that the neighboring cell provides a radio environment suitable for communication to the UE.

[0271] In one embodiment of the present disclosure, individual triggers "DTPSC Trigger" and "NCSM Trigger" are combined using a logical AND function to generate a combined trigger ("Trigger B") as follows.

[0272] For one of the neighboring cells, ["if(DTPSC>Threshold_Distance_ServingCell_CellReselection)"] AND

[0273] ["If((NSM + Δ)>Threshold_SignalMesurement_Neighbor_NTN) for timeToTrigger"], if so, cell reselection is triggered and the neighboring cell selection procedure is executed.

[0274] Such a combined trigger "B" is suitable for Earth-moving beams. The use of the neighbor list of the satellite moving base prevents inaccurate cell reselection (i.e., cell reselection for an adjacent cell that is moving far away from the UE).

[0275] The first part of the combined trigger "B" indicates that the UE is far from the center of the serving cell and close to the boundary of the serving cell, indicating the need for cell reselection. The second part of the combined trigger indicates that the adjacent cell provides a radio environment suitable for communication with the UE.

[0276] The combined trigger "B" is more direct than the combined trigger "A" in that it uses the distance itself instead of the propagation delay as a proxy for the distance.

[0277] In one embodiment of the present disclosure, individual triggers "TSCR Trigger" and "NCSM Trigger" are combined using a logical AND function as follows to generate a combined trigger ("Trigger C").

[0278] For one of the adjacent cells, if ["if(TSLCR>Threshold_Time_CellReselection)"] AND

[0279] ["If((NSM + Δ)>Threshold_SignalMesurement_Neighbor_NTN) for timeToTrigger"], then cell reselection is triggered and the adjacent cell selection procedure is executed.

[0280] Such a combined trigger "C" is suitable for quasi-Earth-Fixed beams and Earth-Moving Beams. The use of the neighbor list of the satellite moving base prevents inaccurate cell reselection (i.e., cell reselection for an adjacent cell that is moving far away from the UE).

[0281] The first part of the combined trigger "C" indicates that sufficient time has elapsed since the last time cell reselection was performed and that the UE can reach an adjacent cell suitable for cell reselection immediately. The second part of the combined trigger indicates that the adjacent cell can provide a radio environment suitable for communication to the UE.

[0282] The combined trigger "C" is also useful for UEs without a gNSS function.

[0283] In one embodiment of the present disclosure, to generate a combined trigger ("Trigger D"), individual triggers "SCEA Trigger" and "NCSM Trigger" are combined using a logical AND function as follows.

[0284] For one of the adjacent cells, ["if(SCEA>Threshold_ServingElevationAngle_NTN)"] AND

[0285] ["If((NSM+Δ)>Threshold_SignalMesurement_Neighbor_NTN) for timeToTrigger"], cell reselection is triggered and the adjacent cell selection procedure is executed.

[0286] This combined trigger "D" is suitable for quasi-Earth-Fixed beams and Earth-Moving Beams. The use of the adjacent list of satellite mobile bases prevents inaccurate cell reselection (i.e., cell reselection for an adjacent cell that is moving far away from the UE).

[0287] The first part of the combined trigger "D" indicates that the UE is far from the center of the serving cell and close to the boundary of the serving cell, indicating the need for cell reselection. The second part of the combined trigger indicates that the adjacent cell can provide a radio environment suitable for communication to the UE.

[0288] In one embodiment of the present disclosure, individual triggers, namely "NCEA Trigger" and "NCSM Trigger", are combined using a logical AND function as follows to generate a combined trigger ("Trigger E").

[0289] For one of the neighboring cells, ["if (NCEA > Threshold_NeighborElevationAngle_NTN)"] AND

[0290] [“If ((NSM + Δ) > Threshold_SignalMesurement_Neighbor_NTN) for timeToTrigger”], cell reselection is triggered and the neighboring cell selection procedure is executed.

[0291] This combined trigger "E" is suitable for quasi-Earth-Fixed beams and Earth-Moving Beams. The use of the neighboring list of the satellite mobile base prevents inaccurate cell reselection (i.e., cell reselection for a neighboring cell that is moving far away from the UE).

[0292] The first part of the combined trigger "E" indicates that the UE is close to the neighboring cell it enters, indicating the need for cell reselection. The second part of the combined trigger indicates that the neighboring cell can actually provide a radio environment suitable for communication to the UE.

[0293] In one embodiment of the present disclosure, individual triggers, namely "SCEA Trigger", "NCEA Trigger", and "NCSM Trigger", are combined using a logical AND function as follows to generate a combined trigger ("Trigger F").

[0294] For one of the neighboring cells, ["if (SCEA > Threshold_ServingElevationAngle_NTN)"] AND

[0295] [“if(NCEA>Threshold_NeighborElevationAngle_NTN)”] AND

[0296] If ((NSM + Δ)> Threshold_SignalMesurement_Neighbor_NTN) for timeToTrigger, cell reselection is triggered and the adjacent cell selection procedure is executed.

[0297] This combined trigger "F" is suitable for quasi-Earth-Fixed beams and Earth-Moving Beams. The use of the adjacent list of the satellite mobile base prevents inaccurate cell reselection (i.e., cell reselection for an adjacent cell that is moving far away from the UE).

[0298] The first part of the combined trigger "F" indicates that the UE is far from the serving cell, the second part of the combined trigger "F" indicates that the UE is close to the adjacent cell to enter, indicating the need for cell reselection. The third part of the combined trigger "F" indicates that the adjacent cell can actually provide a radio environment suitable for communication to the UE.

[0299] In one embodiment of the present disclosure, as a special case, "ASMD Trigger" is used as a single individual trigger without being combined with other individual triggers to generate a combined trigger ("trigger G").

[0300] If any one of the neighboring cells meets the condition of ["If((ASMD<)for timeToTrigger)"], cell reselection is triggered and the neighboring cell selection procedure is executed. To prevent the UE from reselecting the frequency cell due to meeting the same trigger condition "G" within a short period, a timer such as "TriggerGTimer" is started after cell reselection. While this timer "TriggerGTimer" is running, the trigger condition "G" is not evaluated for cell reselection purposes. It should be noted that other trigger conditions (i.e., non-trigger G conditions) are also evaluated by the UE.

[0301] This combined trigger "G" is suitable for Earth-Fixed Beams, quasi-Earth-Fixed beams, and Earth-Moving Beams. The use of the neighboring list of the satellite mobile base prevents inaccurate cell reselection (i.e., cell reselection for a neighboring cell that is moving far away from the UE).

[0302] This trigger can accelerate cell reselection compared to the conventional cell reselection trigger by making the cell reselection for the neighboring cell weaker or stronger than the serving cell.

[0303] In one embodiment of the present disclosure, as a special case, "NSCSM Trigger" is used as a single individual trigger without being combined with other individual triggers to generate a combined trigger ("Trigger H").

[0304] If any one of the neighboring cells meets the condition of ["if((NCSM-SCSM)>Threshold_SignalMesurement_Serving_Neighbor_NTN) for timeToTrigger"], cell reselection is triggered and the neighboring cell selection procedure is executed.

[0305] This combined trigger "H" is suitable for Earth-Fixed Beams, quasi-Earth-Fixed beams, and Earth-Moving Beams. The use of the adjacent list of the satellite movement base prevents inaccurate cell reselection (i.e., cell reselection for adjacent cells that are moving far away from the UE).

[0306] This trigger is intended as a trigger for correcting cell reselection errors. For example, an individual trigger or a combined trigger results in cell reselection for an incorrect adjacent cell (to become the serving cell), but if such an adjacent cell is much better than the serving cell, cell reselection for such a much better candidate cell can be performed.

[0307] In one embodiment of the present disclosure, a number of trigger conditions are specified by the gNB / eNB through system information. One trigger condition is related to one of the combined triggers, and the combined trigger generally combines two or more individual triggers. As a special case, the combined trigger can have only one individual trigger.

[0308] In an exemplary embodiment of the present disclosure, cell reselection is triggered when one or more of the trigger conditions are satisfied for any adjacent cell. This means the use of an OR function for combining different trigger conditions. In other embodiments of the present disclosure, an AND function can be used to combine a number of trigger ring conditions for making a cell reselection decision.

[0309] As one exemplary approach, the adjacent cells evaluated for the trigger ring conditions are explicitly specified through system information. As another exemplary approach, the adjacent cells evaluated by the UE for the trigger ring conditions are autonomously detected by the UE and not explicitly specified through system information.

[0310] In an exemplary embodiment of the approach method, the propagation delay difference between the serving cell and the neighboring cell is combined with one or more other triggers such as the neighboring cell RSRP and time / timer to generate a more reliable combined trigger for cell reselection.

[0311] "Neighboring cell selection" method

[0312] As an exemplary approach method, when a large number of neighboring cells satisfy the cell reselection trigger condition, among these neighboring cells, the neighboring cell with the highest rank is selected (for details, see below).

[0313] In an exemplary embodiment of the present disclosure, the cell ranking criterion Rs for the serving cell and the Rn for the neighboring cell are calculated considering the offset of the satellite mobile base: Rs = Q meas,s + Q hyst - Qoffset temp Rn = Q meas,n - Qoffset - Qoffset temp + Δ

[0314] (Rs = Q meas,s + Q hyst - Qoffset temp , Rn = Q meas,n - Qoffset - Qoffset temp + Δ)

[0315] In an exemplary embodiment, after cell reselection is triggered, without considering Rs and by setting Δ to 0, reselection is performed for the neighboring cell with the highest rank Rn.

[0316] In other exemplary embodiments, after cell reselection is triggered, Δ is set to 0, and if (Rn>Rs) or (Rn>=Rs), reselection is performed for the neighboring cell with the highest rank Rn.

[0317] In another exemplary embodiment, after cell reselection is triggered, when the Δ values set for different adjacent cells are used (Rn>Rs), or if (Rn>=Rs), reselection for the adjacent cell with the highest rank Rn is performed.

[0318] In another exemplary embodiment of the present disclosure, the cell ranking criterion Rn for an adjacent cell is calculated considering the satellite mobility base offset and the number of trigger conditions satisfied by the adjacent cell (hereinafter referred to as numTriggerConditions), where α is an incentive for the gNB / eNB to identify through system information to satisfy the trigger conditions: Rn = Q meas,n - Qoffset - Qoffset temp + Δ + (numTriggerConditions*α)

[0319] (Rn = Q meas,n - Qoffset - Qoffset temp + Δ + (numTriggerConditions*α))

[0320] In that case, after the trigger condition is satisfied, reselection is performed for the adjacent cell with the highest rank Rn without considering Rs.

[0321] In other approach methods, each trigger condition can have its own weighting value α.

[0322] Signaling of satellite mobility base parameters

[0323] In one embodiment of the present disclosure, the offset of the satellite mobility base is specified for each adjacent cell in operations F16S2, F18S2, and / or F19S2.

[0324] In other embodiments of the present disclosure, to reduce overhead in operations F7S2, F8S2, F9S2 and / or F10S2, an offset of the satellite moving base is specified for each set of adjacent cells.

[0325] In yet other embodiments of the present disclosure, the type of adjacent cell is indicated based on the movement of the adjacent cell that utilizes one or more of the following names for the quasi-geostationary beam: "Incoming Neighbor", and "Current Geographic Neighbor", and "Incoming Overlapping Neighbor". The name "Incoming Neighbor" means that the adjacent cell is a geographical adjacent cell of a cell that can provide substantially the same overlapping coverage with respect to the current serving cell. The name "Current Geographic Neighbor" means that this adjacent cell is a geographical neighbor of the current serving cell. The name "Incoming Overlapping Neighbor" means that the adjacent cell is a cell that can provide substantially the same overlapping coverage with respect to the current serving cell.

[0326] Such names of adjacent cells can be used by the UE to prioritize neighbor selection of a given type for the quasi-geostationary beam.

[0327] As an exemplary approach, it is used with a threshold β given a coefficient specific to the neighbor name, and implements prioritization as represented by the following formula. Rn = Q meas,n - Qoffset - Qoffset temp + C * β

[0328] (Rn = Q meas,n - Qoffset - Qoffset temp + C * β)

[0329] Parameter β is used to avoid ping-pong during cell reselection, and coefficient c is used to set different priorities for different types of cells. For example, c can be set to "3" if the adjacent cell "n" is an "Incoming Overlapping Neighbor", "2" if the adjacent cell "n" is an "Incoming Neighbor", and "1" if the adjacent cell "n" is a "Current Geographic Neighbor". A larger positive value of c gives priority to the selection of adjacent cells, and a smaller positive value of c lowers the priority for the selection of adjacent cells.

[0330] Parameter β and coefficient c can be specified by the gNB in operations F16S2, F17S2, F18S2, and / or F19S2.

[0331] In other embodiments of the present disclosure, the type of adjacent cell is indicated based on the movement of the adjacent cell using one or more of the following names for the terrestrial mobile beam: "Incoming Neighbor", "Neutral Neighbor", and "Outgoing Neighbor". The name "Incoming Neighbor" means that the beam of the adjacent cell is moving towards the geographical area currently served by the serving cell, and its design intention is to encourage cell reselection for such adjacent cells. The name "Neutral Neighbor" means that cell reselection for such adjacent cells is neither recommended nor suppressed from the perspective of beam movement. The name "Outgoing Neighbor" means that the beam of the adjacent cell is moving away from the geographical area currently served by the serving cell, and its design intention is to prevent cell reselection for such adjacent cells.

[0332] The names of such neighboring cells can be used by the UE to prioritize the type of neighbor selection given to the earth moving beam.

[0333] As an exemplary approach, it is used with a threshold γ given a coefficient specific to the neighbor name and implements a prioritization as represented by the following equation. Rn = Q meas,n - Qoffset - Qoffset temp + d * γ

[0334] (Rn = Q meas,n - Qoffset - Qoffset temp + d * γ)

[0335] The parameter γ is used to avoid ping-pong during cell reselection, and the coefficient d is used to set different priorities for different types of cells with respect to each other. For example, d is set to "1" if the neighboring cell "n" is an "Incoming Neighbor", "0" if the neighboring cell "n" is a "Neutral Neighbor", and "-1" if the neighboring cell "n" is an "Outgoing Neighbor". A positive (or even larger positive) value of d prioritizes the selection of neighboring cells, and a negative d value lowers the priority for the selection of neighboring cells.

[0336] The parameter γ and the coefficient d can be specified by the gNB in operations F16S2, F17S2, F18S2 and / or F19S2.

[0337] Additional standalone / individual and combined triggers

[0338] The inner area (IA) as a trigger. Since the coverage (applicable range) of the satellite beam on the Earth's surface area is elliptical (not circular), the UE determines whether it is inside or outside the IA of a given beam or cell. In the case of an Earth-fixed beam and an Earth-moving beam, the UE can use the criterion that "the UE is outside the inner area of the serving cell" (or equivalently "the UE is outside the inner area of the serving beam of the serving cell") as a trigger for performing cell reselection. If the UE is outside the IA, this indicates that the UE may search for a suitable neighboring cell for cell reselection within the adjacent overlapping area (i.e., the boundary of two or more cells). The UE can use its position (e.g., latitude and longitude) together with the center, the major axis (or semi-major axis) of the elliptical area, and the minor axis (or semi-minor axis) to determine whether it is inside or outside the IA.

[0339] For example, the UE uses the cell center (i.e., the reference point represented by (cx, cy)), the major axis of the IA (majorAxis = 2a, where a = semi-major axis), the minor axis of the IA (minorAxis = 2b, where b = semi-minor axis), and the position of its GNSS base (ueX, ueY) to determine whether it is inside the IA.

[0340] The UE determines whether it is inside (or on) the IA or uses a specific embodiment method. This is one possible method. The UE calculates the following quantity: comparisonValue=(ueX - cx) 2 / a 2 +(ueY - cy) 2 / b 2 . If comparisonValue <= 1, the UE is inside or on the IA. Otherwise, the UE is outside the IA.

[0341] In one embodiment of the present disclosure, the gNB broadcasts the center, major axis (or major radius), and minor axis (or minor radius) of the elliptical region of its beam in operations F16S2, F17S2, F18S2, and / or F19S2. As an exemplary approach, one or more of the individual triggers previously identified by a single internal region trigger are combined to generate a combined trigger for cell reselection.

[0342] In one embodiment of the present disclosure, individual triggers “Inner Area Trigger” and “NCSM Trigger” are combined using a logical AND function to generate a combined trigger (“Trigger I”).

[0343] For any one of the neighboring cells, [“If the UE is outside the Inner Area of the serving beam of the serving cell”)] AND

[0344] If [“If((NCSM + Δ)> Threshold_SignalMesurement_Neighbor_NTN) for timeToTrigger”], cell reselection is triggered and the neighboring cell selection procedure is executed.

[0345] This combined trigger “I” is suitable for Earth-Fixed Beams, quasi-Earth-Fixed beams, and Earth-Moving Beams.

[0346] The first part of the combined trigger “I” indicates that the UE is far from the center of the serving cell and close to the boundary of the serving cell, indicating the need for cell reselection. The second part of the combined trigger indicates that the neighboring cell can provide a radio environment suitable for communication to the UE.

[0347] In one embodiment of the present disclosure, individual triggers, namely, "Inner Area Trigger", "Serving Cell RSRP / RSRQ Trigger", and "NCSM Trigger", are combined using a logical AND function to generate a combined trigger ("Trigger J") as follows.

[0348] For any one of the neighboring cells, ["If the UE is outside the Inner Area of the serving beam of the serving cell"] AND

[0349] [[ID=8"] ["If the Serving Cell RSRP / RSRQ < RSRP / RSRQ_Threshold"] AND

[0350] If ["If((NSM + Δ)> Threshold_SignalMesurement_Neighbor_NTN) for timeToTrigger"], cell reselection is triggered and the neighboring cell selection procedure is executed.

[0351] This combined trigger "J" is suitable for Earth-Fixed Beams, quasi-Earth-Fixed beams, and Earth-Moving Beams.

[0352] The first two parts of the combined trigger "J" indicate that the UE is far from the center of the serving cell and close to the boundary of the serving cell, indicating the need for cell reselection. The last, or third, part of the combined trigger indicates that the neighboring cell can provide a radio environment suitable for communication with the UE.

[0353] In one embodiment of the present disclosure, individual triggers, namely, "Serving Cell RSRP / RSRQ Trigger" and "NCSM Trigger", are combined using a logical AND function to generate a combined trigger (referred to as "Trigger K") as follows.

[0354] For one of the neighboring cells, [“If the Serving Cell RSRP / RSRQ < RSRP / RSRQ_Threshold”)] AND

[0355] if [“If((NSM+Δ)>Threshold_SignalMesurement_Neighbor_NTN) for timeToTrigger”], cell reselection is triggered and the neighboring cell selection procedure is executed.

[0356] This combined trigger "K" is suitable for Earth-Fixed Beams, quasi-Earth-Fixed beams, and Earth-Moving Beams.

[0357] The first part of the combined trigger "K" indicates that the UE is far from the center of the serving cell and close to the boundary of the serving cell, indicating the need for cell reselection. The second part of the combined trigger indicates that the neighboring cell can provide a radio environment suitable for communication with the UE.

[0358] The serving cell center-UE distance (SCCUD) as one trigger. The UE calculates the distance between the center of the serving cell and itself and determines how close or far it is from the center of the serving cell (or equivalently, the center of the beam of the serving cell). If the UE is far from the center of the serving cell, this indicates that there is a possibility that the UE can find a suitable neighboring cell for cell reselection within the neighboring overlap region (i.e., the boundary of two or more cells).

[0359] In one embodiment of the present disclosure, in operations F16S2, F17S2, F18S2, and / or F19S2, the gNB broadcasts the center of the serving cell and the servingCellDistanceThreshold. As an exemplary approach, a single SCCUD trigger is combined with one or more of the previously identified single triggers to generate a combined trigger for cell reselection.

[0360] In one embodiment of the present disclosure, individual triggers, namely "SCCUD Trigger" and "NCSM Trigger", are combined using a logical AND function to generate a combined trigger (referred to as "Trigger L") as follows.

[0361] For any one of the neighboring cells, [If “UE-Serving Cell Center Distance>servingCellDistanceThreshold”)] AND

[0362] if [“If((NCSM+Δ)>Threshold_SignalMesurement_Neighbor_NTN) for timeToTrigger”], cell reselection is triggered and the neighboring cell selection procedure is executed.

[0363] This combined trigger "L" is suitable for Earth-Fixed Beams, quasi-Earth-Fixed beams, and Earth-Moving Beams.

[0364] The first part of the combined trigger "L" indicates the need for cell reselection by showing that the UE is far from the center of the serving cell and close to the boundary of the serving cell. The second part of the combined trigger shows that the neighboring cell can provide a radio environment suitable for communication to the UE.

[0365] In one embodiment of the present disclosure, individual triggers, namely, "RSRP / RSRQ Trigger", "SCCUD Trigger", and "NCSM Trigger", are combined using a logical AND function to generate a combined trigger ( "Trigger M") as follows.

[0366] [“If the Serving Cell RSRP / RSRQ < RSRP / RSRQ_Threshold”)] AND

[0367] For any one of the neighboring cells, [“If UE-Serving Cell Center Distance>servingCellDistanceThreshold”)] AND

[0368] If [“If((NCSM + Δ)> Threshold_SignalMesurement_Neighbor_NTN) for timeToTrigger”], cell reselection is triggered and the neighboring cell selection procedure is executed.

[0369] This combined trigger "M" is suitable for Earth-Fixed Beams, quasi-Earth-Fixed beams, and Earth-Moving Beams.

[0370] The first two parts of the combined trigger "M" indicate the need for cell reselection by showing that the UE is far from the center of the serving cell and close to the boundary of the serving cell. The third or last part of the combined trigger indicates that the neighboring cell can provide a radio environment suitable for communication to the UE.

[0371] Remaining Serving Time (RST) as a trigger. The UE can calculate the remaining serving time (remainingServingTime) of the current serving cell by subtracting the current time from endServingTime and compare it with a threshold remainingServingTimeThreshold. If the time is short, the UE triggers cell reselection.

[0372] In one embodiment of the present disclosure, in operations F16S2, F17S2, F18S2, and / or F19S2, the gNB broadcasts endServingTime and remainingServingTimeThreshold. As an exemplary approach, a single RST trigger is combined with one or more of the previously identified single triggers to generate a combined trigger for cell reselection. This can be used for quasi-geostationary beams and feeder link switches.

[0373] In one embodiment of the present disclosure, individual triggers, "RST Trigger" and "NCSM Trigger", are combined using a logical AND function as follows to generate a combined trigger ("Trigger N").

[0374] For one of the neighboring cells, ["If remainingServingTime < remainingServingTimeThreshold"] AND

[0375] ["If ((NCSM + Δ) > Threshold_SignalMesurement_Neighbor_NTN) for timeToTrigger"], cell reselection is triggered and the neighboring cell selection procedure is executed.

[0376] This combined trigger "n" is suitable for quasi-geostationary beams and geostationary mobile beams, and for feeder link switches for quasi-geostationary beams and geostationary mobile beams.

[0377] The first part of the combined trigger “n” indicates the need for cell reselection. The second part of the combined trigger indicates that the neighboring cell can provide a radio environment suitable for communication to the UE.

[0378] In one embodiment of the present disclosure, the following conditions are evaluated by the UE to perform fallback cell reselection (“Trigger O”).

[0379] If “remainingServingTime < fallbackThreshold”, cell reselection is triggered and the UE performs cell reselection for the fallback neighboring cell.

[0380] This combined trigger “O” is suitable for quasi-geostationary beams and for feeder link switches for geostationary and geostationary mobile beams.

[0381] In one embodiment of the present disclosure, in operations F16S2, F17S2, F18S2, and / or F19S2, the gNB broadcasts the FallbackThreshold and the identifier of the fallback neighboring cell.

[0382] In other embodiments, the fallbackThreshold is specified as endServingTime - timeMargin, and the timeMargin is broadcast through system information instead of the fallbackThreshold.

[0383] In one embodiment of the present disclosure, when the UE is not triggered by any condition where cell reselection is not trigger "O", the UE performs cell reselection for the fallback adjacent cell. As another approach, the UE performs cell reselection for the fallback adjacent cell when no adjacent cell has a rank better than the current serving cell. Cell reselection for the fallback adjacent cell is performed when the conditions related to trigger "O" are satisfied.

[0384] In one embodiment of the present disclosure, the following conditions are evaluated by the UE to perform fallback cell reselection ("Trigger P").

[0385] If “dwellTime > maxServingTimeThreshold”, cell reselection is triggered and the UE performs cell reselection for the fallback adjacent cell. The variable dwellTime is the elapsed time after cell selection or reselection for the current serving cell, and maxServingTimeThreshold specifies the maximum period during which the terrestrial mobile beam covers a predetermined point on the terrestrial surface area.

[0386] Such a combined trigger "P" is suitable for the terrestrial mobile beam.

[0387] In one embodiment of the present disclosure, in operations F16S2, F17S2, F18S2, and / or F19S2, the gNB broadcasts the maxServingTimeThreshold and the identifier of the fallback adjacent cell.

[0388] In one embodiment of the present disclosure, when the UE is not triggered by any condition where cell reselection is not trigger "P", the UE performs cell reselection for the fallback neighbor cell. As another approach, when no neighbor cell has a rank better than the current serving cell, the UE performs cell reselection for the fallback neighbor cell; the cell reselection for the fallback neighbor cell is performed when the conditions related to trigger "P" are satisfied.

[0389] FIG. 20 is a flowchart showing a method 2000 of operating a UE, which can be performed by a UE such as UE 116 according to an embodiment of the present disclosure. The embodiment of the method 2000 illustrated in FIG. 20 is for illustrative purposes only. FIG. 20 does not limit the scope of the present disclosure to a specific implementation.

[0390] As illustrated in FIG. 20, the method 2000 starts at step 2002. At step 2002, the UE (e.g., 111 to 116 as illustrated in FIG. 1) receives system information including information corresponding to the location coordinates of the non-terrestrial network (NTN) gateway; information corresponding to the processing delay between the UE and the base station (BS); and information corresponding to the reference point location.

[0391] At step 2004, the UE determines the timing advance based on the timing difference between the reference point location and the BS.

[0392] At step 2006, the UE transmits a timing advance report based on the determined timing advance.

[0393] In one embodiment, the UE automatically transmits a timing advance report, transmits a timing advance report periodically, or transmits a timing advance report according to an instruction from the BS when the condition is satisfied or when random access is performed.

[0394] In one embodiment, the UE transmits a timing advance report via a Radio Resource Control (RRC) message or via a Medium Access Control (MAC) control element (CE).

[0395] In one embodiment, the system information includes long-term satellite ephemeris data, and changes in the long-term satellite ephemeris data are transmitted via a flag.

[0396] In one embodiment, the UE receives the position and velocity data included in the system information at a first period and a second period, respectively.

[0397] In one embodiment, when the system information includes the disable-s-IntraSearchP parameter, the UE searches for adjacent cells.

[0398] In one embodiment, the system information includes adjacent cell selection information, and the UE prioritizes incoming cells over outgoing cells based on the adjacent cell selection information.

[0399] In one embodiment, the system information further includes elliptical cell information including the center, the minor axis or semi-minor axis, and the major axis or semi-major axis of the inner region of the serving cell, and the UE determines whether the UE is within the inner region of the serving cell based on the elliptical cell information and the position of the UE. When the UE is outside the inner region of the serving cell and the signal measurement value of an adjacent cell satisfies a threshold, the UE transmits a measurement report or selects the adjacent cell as the serving cell.

[0400] FIG. 21 is a flowchart showing another method 2100 that can be performed by a BS such as BS 102 according to an embodiment of the present disclosure. The embodiment of the method 2100 illustrated in FIG. 21 is for illustrative purposes only. FIG. 21 does not limit the scope of the present disclosure to a specific implementation example.

[0401] As shown in FIG. 21, the method 2100 starts with operation 2102. In operation 2102, a BS (e.g., 101 to 103 as shown in FIG. 1) generates system information including information corresponding to the position coordinates of a non-terrestrial network (NTN) gateway; information corresponding to the processing delay between a UE and a base station; and information corresponding to a reference point position.

[0402] In operation 2104, the BS transmits the system information.

[0403] In operation 2106, the BS receives a timing advance report based on a timing advance, where the timing advance is based on the timing difference between a reference point position and the base station.

[0404] In one embodiment, the BS automatically receives a timing advance report, receives a timing advance report periodically, or receives a timing advance report by an instruction from the BS when a condition is satisfied or when random access is performed.

[0405] In one embodiment, the BS receives a BS timing advance report via a radio resource control (RRC) message or a medium access control (MAC) control element (CE).

[0406] In one embodiment, the system information includes long-term satellite ephemeris data, and changes in the long-term satellite ephemeris data are transmitted via a flag.

[0407] In one embodiment, the BS transmits the position and velocity data included in the system information at a first period and a second period, respectively.

[0408] In one embodiment, the disable-s-IntraSearchP parameter included in the system information is used for adjacent cell search.

[0409] In one embodiment, the system information includes adjacent cell selection information indicating that input cells are given priority over output cells.

[0410] In one embodiment, the system information further includes elliptical cell information including the center, minor axis or semi - minor axis, and major axis or semi - major axis of the internal area of the serving cell. When an indication that the user equipment (UE) is outside the internal area of the serving cell is received and the signal measurement value of an adjacent cell satisfies a threshold, a measurement report is received or the adjacent cell is selected as the serving cell.

[0411] The flowchart illustrates an exemplary method that can be implemented according to the principles of the present disclosure, and various changes can be made to the method illustrated in the flowchart. For example, although a series of operations are illustrated, various operations may overlap, occur in parallel, occur in different orders from each other, or occur multiple times in each drawing. In other examples, operations may be omitted or replaced by other operations.

[0412] FIG. 22 schematically illustrates a base station according to an embodiment of the present disclosure.

[0413] Referring to FIG. 22, the base station 2000 includes a processor 2210, a transceiver 2220, and a memory 2230. However, none of the illustrated components are essential. The base station 2000 can be implemented with more or fewer components than those illustrated in FIG. 22. Also, the processor 2210, the transceiver 2220, and the memory 2230 can be implemented as a single chip according to other embodiments.

[0414] In an exemplary embodiment, the base station 2000 is also a gNodeB (gNB). In an exemplary embodiment, the aforementioned gNBs 101, 102, and 103 can correspond to the base station 2000.

[0415] The above - described components will be described in detail below.

[0416] The processor 2210 includes one or more processors or other processing devices that control the proposed functions, processes, and / or methods. The operation of the base station 2000 can be implemented by the processor 2210.

[0417] The transceiver 2220 includes an RF transmitter for up-converting and amplifying the signal to be transmitted, and an RF receiver for down-converting the frequency of the received signal. However, according to other embodiments, the transceiver 2220 can be implemented with more or fewer components than the illustrated components.

[0418] The transceiver 2220 is connected to the processor 2210 and can transmit and / or receive signals. The signals can include control information and data. Also, the transceiver 2220 can receive a signal via a wireless channel and output the signal to the processor 2210. The transceiver 2220 can transmit the signal output from the processor 2210 via a wireless channel.

[0419] The memory 2230 can store the control information or data included in the signal obtained by the base station 2000. The memory 2230 is connected to the processor 2210 and can store at least one instruction word or protocol or parameter related to the proposed functions, processes, and / or methods. The memory 2230 can include a ROM (read-only memory) and / or a RAM (random access memory) and / or a hard disk and / or a CD-ROM and / or a DVD and / or other storage elements.

[0420] FIG. 23 illustrates a user equipment (UE) according to an embodiment of the present disclosure.

[0421] Referring to FIG. 23, the UE 2300 includes a processor 2310, a transceiver 2320, and a memory 2330. However, none of the illustrated components are essential. The UE 2300 may be implemented with more or fewer components than those illustrated in FIG. 23. Also, the processor 2310, the transceiver 2320, and the memory 2330 may be implemented as a single chip according to other embodiments.

[0422] For example, the UEs 111-116 illustrated in FIG. 1 may correspond to the UE 2300.

[0423] The above-described components will be described in detail below.

[0424] The processor 2310 includes one or more processors or other processing devices that control the proposed functions, processes, and / or methods. The operations of the UE 2300 described above may be implemented by the processor 2310.

[0425] The transceiver 2320 includes an RF transmitter for up-converting and amplifying the transmitted signal, and an RF receiver for down-converting the frequency of the received signal. However, according to other embodiments, the transceiver 2320 may be implemented with more or fewer components than those illustrated.

[0426] The transceiver 2320 is connected to the processor 2310 and can transmit and / or receive signals. The signals may include control information and data. Also, the transceiver 2320 can receive signals via a wireless channel and output the signals to the processor 2310. The transceiver 2320 can transmit the signals output from the processor 2310 via a wireless channel.

[0427] Memory 2330 can store control information or data included in the signals obtained by UE 2300. Memory 2330 is connected to processor 2310 and can store at least one instruction word or protocol or parameter related to the proposed function, process, and / or method. Memory 2330 can include ROM (read-only memory) and / or RAM (random access memory) and / or a hard disk and / or a CD-ROM and / or a DVD and / or other storage elements.

[0428] The present invention has been described with exemplary embodiments, but various changes and amendments can be proposed to those skilled in the art. This disclosure is intended to include changes and modifications within the scope of the claims. The content of this application should not be construed as meaning that specific elements, operations, or functions are essential components that must be included in the claims. The patent scope of the present invention is limited by the claims.

Explanation of Signs

[0429] 2210 Processor 2220 Transceiver 2230 Memory 2310 Processor 2320 Transceiver 2330 Memory

Claims

1. A user equipment (UE), comprising: a transceiver configured to receive system information including information corresponding to the position coordinates of a non-terrestrial network (NTN) gateway; information corresponding to the processing delay between the UE and a base station (BS); and information corresponding to a reference point position; a processor operably coupled to the transceiver and configured to determine a timing advance based on a time difference between the reference point position and the BS; wherein the transceiver is further configured to transmit a timing advance report based on the determined timing advance.

2. The transceiver is configured to automatically transmit the timing advance report when a condition is satisfied or when random access is performed, transmit the timing advance report periodically, or transmit the timing advance report according to an instruction from the BS.

3. The transceiver of claim 1 is configured to transmit the timing advance report via a radio resource control (RRC) message or through a medium access control (MAC) control element (CE).

4. The system information of claim 1 includes long-term satellite ephemeris data, and changes in the long-term satellite ephemeris data are transmitted via a flag.

5. The transceiver of claim 1 is configured to receive the position and velocity data included in the system information at a first period and a second period, respectively.

6. When the system information includes a disable-s-IntraSearchP parameter, the processor of claim 1 is configured to search for adjacent cells.

7. The system information includes adjacent cell selection information, and the processor of claim 1 is configured to prioritize an input cell over an output cell based on the adjacent cell selection information.

8. The system information further includes elliptical cell information including the center, minor axis or semi-minor axis, and major axis or semi-major axis of the inner area of a serving cell, and the processor of claim 1 is further configured to determine whether the UE is located within the inner area of the serving cell based on the elliptical cell information and the position of the UE. When the UE is outside the internal area of the serving cell and the signal measurement value of an adjacent cell satisfies a threshold, the processor is configured to transmit a measurement report or select the adjacent cell as the serving cell. The UE according to claim 1.

9. A base station (BS), A processor configured to generate system information including information corresponding to the position coordinates of a non-terrestrial network (NTN) gateway; information corresponding to the processing delay between a user equipment (UE) and the base station; and information corresponding to a reference point position; A transceiver operably coupled to the processor, configured to transmit the system information and receive a timing advance report based on a timing advance. The timing advance is based on the time (timing) difference between the reference point position and the base station. The base station.

10. The system information includes long-term satellite ephemeris data, and changes in the long-term satellite ephemeris data are transmitted via a flag. The BS according to claim 9.

11. The transceiver is configured to transmit the position and velocity data included in the system information at a first period and a second period, respectively. The BS according to claim 9.

12. The disable-s-IntraSearchP parameter included in the system information is used for adjacent cell search. The BS according to claim 9.

13. The system information includes adjacent cell selection information indicating that an input cell is prioritized over an output cell. The BS according to claim 9.

14. The system information further includes elliptical cell information including the center, minor axis or semi-minor axis, and major axis or semi-major axis of the internal area of the serving cell. When an indication that the user equipment (UE) is outside the internal area of the serving cell is received and the signal measurement value of an adjacent cell satisfies a threshold, a measurement report is received or the adjacent cell is selected as the serving cell. The BS according to claim 9.

15. A method of operating a user equipment (UE), Receiving system information including information corresponding to the position coordinates of a non-terrestrial network (NTN) gateway; information corresponding to the processing delay between the UE and a base station (BS); and information corresponding to a reference point position; Determining a timing advance based on a time (timing) difference between the reference point position and the BS; Transmitting a timing advance report based on the determined timing advance. A method including these steps.

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