Management of ephemeris, time, delays and ta for ntn

Abstract

To provide management of ephemeris, time, delays and TA for an NTN.SOLUTION: A method for operating user equipment (UE) comprises receiving system information including: information corresponding to location coordinates for a non-terrestrial network (NTN) gateway; information corresponding to a processing delay between the UE and a base station (BS); and information corresponding to a reference point location. The method also comprises: determining a timing advance based on a timing difference between the reference point location and the BS; and transmitting a timing advance report based on the determined timing advance.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present invention relates generally to wireless communication systems, and more particularly to satellite almanac, time, delay and TA management for NTNs. [Background technology]

[0002] To meet the increasing demand for wireless data traffic following the deployment of fourth-generation (4G) communication systems, efforts are underway to develop improved fifth-generation (5G) or pre-5G communication systems. 5G or pre-5G communication systems are also referred to as "beyond 4G networks" or "post-LTE (post long term evolution) systems." To achieve higher data rates, 5G communication systems are expected to be implemented in higher frequency (mmWave) bands, such as the 60 GHz band. To reduce radio wave propagation loss and extend transmission distances, beamforming, massive MIMO (multiple-input multiple-output), full-dimensional MIMO (FD-MIMO), array antennas, analog beamforming, and large-scale antenna techniques are being discussed for 5G communication systems. Furthermore, in the 5G communication system, development is underway to improve the system network based on advanced small cells, cloud radio access networks (RANs), ultra-high density networks, device-to-device (D2D) communications, wireless backhaul, mobile networks, cooperative communications, coordinated multi-points (CoMP), receiver-end interference cancellation, etc. In the 5G system, advanced coding modulation (ACM) technologies developed include hybrid frequency shift keying (FSK), Feher's quadrature amplitude modulation (FQAM), and sliding window superposition coding (SWSC), and advanced access technologies such as filter bank multicarrier (FBMC), non-orthogonal multiple access (NOMA), and sparse code multiple access (SCMA).

[0003] The Internet, a human-centered network where humans generate and consume information, is currently evolving into the Internet of Things (IoT), where distributed entities like objects exchange and process information without human intervention. The Internet of Everything (IoE) has emerged, combining IoT technology with big data processing technology via cloud servers. Technological elements required for the realization of IoT include sensing technology, wired / wireless communication and network infrastructure, service interface technology, and security technology. Research is currently focused on M2M (machine-to-machine) communication and MTC (machine-type communication). Such an IoT environment can provide intelligent Internet technology services that create new value in human life by collecting and analyzing data generated between connected objects. Through the integration and combination of existing information technology (IT) and various industrial applications, IoT can be applied to a variety of fields, including smart homes, smart buildings, smart cities, smart or connected cars, smart grids, healthcare, smart home appliances, and advanced medical services.

[0004] Accordingly, various attempts have been made to apply 5G communication systems to IoT networks. For example, technologies such as sensor networks, MTC, and M2M communication are also implemented using beamforming, MIMO, and array antennas. The application of Cloud RAN, the big data processing technology mentioned above, can also be seen as an example of the integration between 5G technology and IoT technology.

[0005] As described above, with the development of wireless communication systems, a variety of services are provided, and therefore, a method for easily providing such services is required. Summary of the Invention [Means for solving the problem]

[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 location coordinates of a non-terrestrial network (NTN) gateway, information corresponding to a processing delay between the UE and a base station (BS), and information corresponding to a reference point location. The processor is configured to determine a timing advance based on a time difference between the reference point location and the BS. The transceiver is also configured to transmit a timing advance report based on the determined timing advance. [Brief explanation 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 indicate like elements and in which:

[0008] [Figure 1] 1 is a drawing illustrating an example wireless network according to an embodiment of the present disclosure. [Figure 2] 1 is a diagram illustrating an exemplary gNB according to an embodiment of the present disclosure. [Figure 3] 1 is a diagram illustrating an example UE according to an embodiment of the present disclosure. [Figure 4] 1 is a diagram illustrating an example wireless transmission path according to an embodiment of the present disclosure. [Figure 5] 1 is a diagram illustrating an example wireless receive path according to an embodiment of the present disclosure. [Figure 6] 1 is a diagram illustrating an example of distance estimation according to an embodiment of the present disclosure. [Figure 7] 1 is a diagram illustrating an example operation of satellite ephemeris, time, and delay management according to an embodiment of the present disclosure. [Figure 8] 1 is a diagram illustrating an example of satellite almanac, time and delay management operations according to an embodiment of the present disclosure. [Figure 9]1 is a diagram illustrating an example of a general UE-network procedure for managing satellite ephemeris, time, and delay according to an embodiment of the present disclosure. [Figure 10] 1 is a flowchart illustrating an example gNB procedure for supporting satellite almanac and TA management in accordance with an embodiment of the present disclosure. [Figure 11] 1 is a flowchart illustrating an example UE procedure for supporting satellite almanac and TA management according to an embodiment of the present disclosure. [Figure 12] 1 is a diagram illustrating a proposed structure for supporting management of time, almanac, and other aspects of an NTN according to an embodiment of the present disclosure. [Figure 13] 1 is a diagram illustrating a proposed structure for supporting management of time, almanac, and other aspects of an NTN according to an embodiment of the present disclosure. [Figure 14] 1 is a diagram illustrating an example of the operation of a flexible cell reselection scheme according to an embodiment of the present disclosure. [Figure 15] 1 is a diagram illustrating an example of an operation for implementing flexible QoS according to an embodiment of the present disclosure. [Figure 16] 1 is a diagram illustrating an example of a general UE-network procedure for a flexible cell reselection scheme in an NTN according to an embodiment of the present disclosure. [Figure 17] 1 is a diagram illustrating an example of a general UE-network procedure for a flexible cell reselection scheme in an NTN according to an embodiment of the present disclosure. [Figure 18] 1 is a diagram illustrating an example UE procedure for a flexible cell reselection scheme for NTN according to an embodiment of the present disclosure. [Figure 19] 1 is a diagram illustrating an example of an exemplary network procedure for a flexible cell reselection scheme for an NTN according to an embodiment of the present disclosure. [Figure 20] 1 is a flowchart illustrating a method of operating a UE according to an embodiment of the present disclosure. [Figure 21] 10 is a flowchart illustrating another method that can be performed by a BS according to an embodiment of the present disclosure. [Figure 22]1 is a diagram illustrating a base station (BS) according to an embodiment of the present disclosure. [Figure 23] 1 is a diagram illustrating a user equipment (UE) according to an embodiment of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0009] The present invention relates to wireless communication systems, and more particularly to satellite almanac, time, delay, and timing advance (TA) management for NTNs. Some components of the present disclosure can be used with both terrestrial networks (TNs) and non-terrestrial networks (NTNs), and certain components significantly improve NTN performance.

[0010] According to one embodiment of the present disclosure, a user equipment (UE) is proposed. The UE is configured to receive system information including information corresponding to location coordinates of a non-terrestrial network (NTN) gateway; information corresponding to a processing delay between the UE and a base station (BS); and information corresponding to a reference point location. The UE also includes a processor operably coupled to the transceiver. The processor is configured to determine a timing advance based on a time difference between the reference point location and the BS. The transceiver is also 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 when a condition is met or when random access is performed, to periodically transmit a timing advance report, or to transmit a timing advance report upon command from the BS.

[0012] In one embodiment, the transceiver is configured to transmit the 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 almanac data, and changes in the long term satellite almanac data are communicated via flags.

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

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

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

[0017] In one embodiment, the system information further includes elliptical cell information including a center, a minor axis or semi-minor axis, and a major axis or semi-major axis of an inner area of the serving cell. The processor is further configured to determine whether the UE is within the inner area of the serving cell based on the elliptical cell information and the location of the UE. When the UE is outside the inner area of the serving cell and a 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] According to another embodiment of the present disclosure, a base station is proposed. The base station is configured to generate system information including information corresponding to location coordinates of a non-terrestrial network (NTN) gateway, information corresponding to a processing delay between a user equipment (UE) and the base station, and information corresponding to a reference point location. The base station also includes a transceiver operably coupled to the 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 a time difference between the reference point location and the base station.

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

[0020] In one embodiment, the transceiver is configured to receive timing advance reports 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 almanac data, and changes in the long term satellite almanac data are communicated via flags.

[0022] In one embodiment, the transceiver is configured to receive 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 neighbor cell search.

[0024] In one embodiment, the system information includes neighbor cell selection information that indicates that an input cell is to be preferred over an output cell.

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

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

[0027] In one embodiment, the method further includes the steps of automatically transmitting a timing advance report when a condition is met or random access is performed; periodically transmitting the timing advance report; or transmitting the timing advance report upon command 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 almanac data, and changes in the long term satellite almanac data are communicated via flags.

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

[0031] Before proceeding with the detailed description, it is advisable to provide definitions of certain words and phrases used throughout this patent document. The term "coupled" and its derivatives refer to direct or indirect communication between two or more elements, 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 "comprise" and "comprise" and their derivatives mean inclusive without limitation. "Or" is an inclusive term meaning "and / or." The term "related to" and its derivatives means "comprise," "contained within," "connected with," "contain," "involve," "contain in," "coupled to," "coupled with," "capable of communicating with," "cooperate with," "intervene," "align," "approximate," "bound by," "have," "have the characteristic of," or "relate to." The term "controller" means a device, system, or part thereof that controls at least one operation. Such controllers may be implemented using hardware or a combination of hardware, software, and / or firmware. The functionality associated with a particular controller may be centralized or distributed, whether locally or remotely. "At least one of," when used in conjunction with a list of items, means that one or more different combinations of the listed items may be 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 A, B, C, A and B, A and C, B and C, and A, B, and C.

[0032] Additionally, the various functions described below may be implemented or supported by one or more computer programs, each of which may be configured as computer-readable program code and embodied in 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, associated data, or portions thereof suitable for implementation as computer-readable program code. The term "computer-readable program code" includes all types of computer code, including source code, object code, and executable code. The term "computer-readable medium" includes any type of medium that can be accessed by a computer, such as read-only memory (ROM), random access memory (RAM), hard disk drive, compact disc (CD), digital video disc (DVD), or any other type of memory. The term "non-transitory" computer-readable medium excludes wired, wireless, optical, or other communication links that transmit transient electrical or other signals. Non-transitory computer-readable media include media on which data can be permanently stored and media on which data can be stored and then overwritten, such as rewritable optical disks and removable memory devices.

[0033] Definitions for certain other words and phrases are provided throughout the patent document, and those skilled in the art will understand that in many, if not most, cases, such definitions also apply to previous and subsequent uses of the words and phrases so defined.

[0034] Recently, momentum for 5G (5th generation) or NR (new radio) mobile communications has accelerated with all the global technical activity on various candidate technologies from industry and academia. Potential enablers of 5G / NR mobile communications include large antenna technologies from conventional cellular frequency bands to higher frequency bands to provide beamforming gain and support improved functionality, new waveforms (e.g., new radio access technologies (RATs)) to flexibly accommodate various services / applications with different requirements, and new multiple access methods to support massive connectivity.

[0035] 1-21 discussed below, and the various embodiments used to describe the principles of the present disclosure in this patent document, are illustrative only and should not be construed as limiting the scope of the present disclosure in any way. Those skilled in the art will understand that the principles of the present disclosure may be embodied in any suitably arranged system or device.

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

[0037] 1-3 below illustrate various embodiments that may be 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 contents of FIGS. 1-3 are not meant to imply physical or architectural limitations to the manner in which other embodiments may be implemented. Other embodiments of the present disclosure may be implemented by any suitably configured communication system.

[0038] 1 illustrates an exemplary wireless network according to an embodiment of the present disclosure. The embodiment of wireless network 100 illustrated in FIG. 1 is for illustrative purposes only. Other embodiments of wireless network 100 may be used without departing from the scope of this disclosure.

[0039] 1, 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. gNB 101 also communicates with at least one network 130, such as the Internet, a private Internet Protocol (IP) network, or other data network.

[0040] gNB 102 provides wireless wide-area access to network 130 for a first plurality of user equipments (UEs) within its coverage area 120. The first plurality of UEs includes UE 111 located within a small business premises, UE 112 located within an enterprise (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 may be 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 its coverage area 125. The second plurality of UEs includes UE 115 and UE 116. In some embodiments, one or more of the gNBs 101-103 can communicate with each other and with the 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" may refer to any component (or collection of components) configured to provide wireless access to a network, such as a transmission point (TP), transmit / receive point (TRP), enhanced base station (eNodeB or eNB), 5G base station (gNB), macrocell, femtocell, WiFi access point (AP), or other wireless-enabled device. A base station may provide wireless access via one or more wireless communication protocols, e.g., 3GPP® 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 network infrastructure components that provide wireless access to remote terminals. Also, depending on the network type, "user equipment" or "UE" may refer to any entity such as a "mobile station," "subscriber station," "remote terminal," "wireless terminal," "receiving point," or "user equipment." For convenience, the terms "user equipment" and "UE" are used in this patent document to refer to a remote wireless device that wirelessly accesses a BS, whether the UE is a mobile device (such as a mobile phone or smartphone) or is generally considered a fixed device (such as a desktop computer or vending machine).

[0042] The dotted lines indicate the approximate extent of coverage areas 120 and 125, which are shown as approximately circular for purposes of illustration and explanation only. It will be clearly understood that coverage areas associated with gNBs, such as coverage areas 120 and 125, may have other shapes, including irregular shapes, due to variations in the radio environment associated with natural and man-made obstructions and the configuration of the gNB.

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

[0044] As discussed in further detail below, wireless network 100 may enable communication via one or more communications satellites 104 in orbit around the Earth. Communications satellites 104 may communicate directly with BSs 102 and 103 to provide network access in situations where, for example, BSs 102 and 103 are far apart or disparate and require a network access connection beyond or in addition to a fronthaul and / or backhaul connection. Various UEs (e.g., represented as UE 116) may communicate at least in part directly with communications satellites 104 and / or perform localization, for example, to receive location information or coordinates.

[0045] While FIG. 1 illustrates an example wireless network, various variations on FIG. 1 are possible. For example, a wireless network may include any number of gNBs and any number of UEs in any suitable arrangement. Furthermore, gNB 101 may directly communicate with any number of UEs and provide the UEs with wireless wide area access to network 130. Similarly, each of gNBs 102-103 may directly communicate with network 130 and provide the UEs with direct wireless wide area access to network 130. Furthermore, gNBs 101, 102, and / or 103 may provide access to other or additional external networks, such as an external telephone network or a different type of data network.

[0046] Figure 2 illustrates an exemplary gNB 102 according to an embodiment of the present disclosure. The embodiment of gNB 102 illustrated in Figure 2 is for illustrative purposes only, and gNBs 101 and 103 of Figure 1 may have the same or similar configuration. However, gNBs come in a wide variety of configurations, and Figure 2 does not limit the scope of the present disclosure to any particular implementation of a gNB.

[0047] 2, gNB 102 includes multiple antennas 205a-205n, multiple radio frequency (RF) transceivers 210a-210n, transmit (TX) processing circuitry 215, and receive (RX) processing circuitry 220. gNB 102 also includes a controller / processor 225, 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 in the network 100 from the antennas 205a-205n. The RF transceivers 210a-210n downconvert the incoming RF signals to generate IF or baseband signals. The IF or baseband signals are transmitted to the RX processing circuitry 220, which filters, decodes, and / or binarizes the baseband or IF signals to generate processed baseband signals. The RX processing circuitry 220 transmits the processed baseband signals to the controller / processor 225 for further processing.

[0049] TX processing circuitry 215 receives analog and digital data (such as voice data, web data, email, or interactive video game data) from controller / processor 225. TX processing circuitry 215 encodes, multiplexes, and / or binarizes the outgoing baseband data and generates processed baseband or IF signals. RF transceivers 210a-210n receive the outgoing processed baseband or IF signals from TX processing circuitry 215 and upconvert the baseband or IF signals to RF signals that are transmitted via antennas 205a-205n.

[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 may control the reception of forward channel signals and the transmission of reverse channel signals by the RF transceivers 210a-210n, the RX processing circuitry 220, and the TX processing circuitry 215 according to well-known principles. The controller / processor 225 may also support additional functionality, such as more advanced wireless communication functions. For example, the controller / processor 225 may support beamforming or directional routing operations that differentially weight outgoing / incoming signals to / from multiple antennas 205a-205n to effectively steer them in desired directions. Any one of a wide range of other functions may be supported within the gNB 102 by the controller / processor 225.

[0051] Controller / processor 225 may also run programs and other processes that reside in memory 230, such as an operating system. Controller / processor 225 may move data in and out of memory 230 as required by executing processes.

[0052] The controller / processor 225 is also coupled to a 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 network. The interface 235 may support communication via any suitable wired or wireless connection. For example, if the gNB 102 is embodied as part of a cellular communication system (such as one supporting 5G / NR, LTE / NR, or LTE-A), the interface 235 may enable the gNB 102 to communicate with gNBs over a wired or wireless backhaul connection. If the gNB 102 is embodied as an access point, the interface 235 may 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 may include any suitable structure that supports communication via a wired or wireless connection, such as an Ethernet or RF transceiver.

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

[0054] While FIG. 2 illustrates one example of a gNB 102, various modifications to FIG. 2 may be made. For example, the gNB 102 may include a predetermined number of each of the components illustrated in FIG. 2. As a particular example, an access point may include multiple interfaces 235. As another particular example, while illustrated as including one instance of the TX processing circuit 215 and one instance of the RX processing circuit 220, the gNB 102 may include multiple instances of each (e.g., one per RF transceiver). Also, various components within FIG. 2 may be combined, further subdivided, or omitted, and additional components may be added according to particular needs.

[0055] 3 illustrates an exemplary UE 116 according to an embodiment of the present disclosure. The embodiment of the UE 116 illustrated in FIG. 3 is merely exemplary, and the UEs 111-115 of FIG. 1 may have the same or similar configurations. However, UEs may be embodied in a wide variety of configurations, and FIG. 3 does not limit the scope of the present disclosure to any particular implementation of a UE.

[0056] 3, the 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. The UE 116 also includes a speaker 330, a processor 340, an input / output (I / O) interface (IF) 345, a touchscreen 350, a display 355, and memory 360. The memory 360 includes an operating system (OS) 361 and one or more applications 362.

[0057] The RF transceiver 310 receives incoming RF signals transmitted by gNBs in the network 100 from the antenna 305. The RF transceiver 310 downconverts the incoming RF signals to generate intermediate frequency (IF) or baseband signals. The IF or baseband signals are transmitted to the RX processing circuitry 325, which filters, decodes, and / or binarizes the baseband or IF signals to generate processed baseband signals. The RX processing circuitry 325 transmits the processed baseband signals to a speaker 330 (e.g., for voice data) or to a processor 340 (e.g., for web browsing data).

[0058] TX processing circuitry 315 receives analog or digital voice data from microphone 320 or other outgoing baseband data (such as web data, email, or interactive video game data) from processor 340. TX processing circuitry 315 encodes, multiplexes, and / or binarizes the outgoing baseband data and generates a processed baseband or IF signal. RF transceiver 310 receives the outgoing processed baseband or IF signal from TX processing circuitry 315 and upconverts the baseband or IF signal to an RF signal for transmission via antenna 305.

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

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

[0061] Processor 340 is also coupled to touchscreen 350 and display 355. An operator of UE 116 can use touchscreen 350 to input data into UE 116. Display 355 may be a liquid crystal display, a light emitting diode display, or other display that renders text and / or at least limited graphics, such as from a website.

[0062] Memory 360 is coupled to processor 340. A portion of memory 360 may include random access memory (RAM), and another portion of memory 360 may include flash memory or other read-only memory (ROM).

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

[0064] Following the use of 4G communication systems, 5G / NR communication systems have been developed and are currently being used to meet the increasing demand for wireless data traffic and carry out a variety of vertical applications. 5G / NR communication systems are expected to be implemented in higher frequency (mmWave) bands such as the 28 GHz or 60 GHz bands to achieve higher data rates, or in lower frequency bands such as 6 GHz to enable strong coverage and mobility support. To reduce radio wave loss and extend transmission distances, beamforming, massive MIMO (multiple-input multiple-output), full-dimensional MIMO (FD-MIMO), array antennas, analog beamforming, and large-scale antenna techniques are being discussed for 5G / NR communication systems.

[0065] In addition, in the 5G / NR communication system, development is underway to improve the system network based on advanced small cells, cloud radio access networks (RANs), ultra-high density networks, device-to-device (D2D) communications, wireless backhaul, mobile networks, cooperative communications, Coordinated Multi-Points (CoMP), and receiver-end interference cancellation.

[0066] Because certain embodiments of the present disclosure may be implemented in a 5G system, reference will be made to a discussion of the 5G system and associated frequency bands. However, the present disclosure is not limited to the 5G system or associated frequency bands, and embodiments of the present disclosure may be used in connection with any frequency band. For example, aspects of the present disclosure may be applied to the use of a 5G communication system, or 6G or subsequent versions that can use the THz band.

[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 a UE to a base station or one or more reception points.

[0068] A time unit for DL or UL signaling on a cell is called a slot and contains one or more symbols. A symbol can also serve as an additional time unit. A frequency (or bandwidth (BW)) unit is called a resource block (RB). One RB contains several subcarriers (SCs). For example, one slot has a duration of 0.5 ms or 1 ms and contains 14 symbols, and an RB contains 12 SCs with an inter-SC spacing of 15 kHz or 30 kHz.

[0069] DL signals include data signals carrying information content, control signals carrying DL control information (DCI), and reference signals (RS), also known as pilot signals. The gNB transmits data information or DCI via a dedicated 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 for scheduling PDSCH reception by a UE is referred to as DL DCI, and a DCI format for scheduling physical uplink shared channel (PUSCH) transmission from a UE is referred to as UL DCI format.

[0070] The gNB transmits one or more of various types of RSs, including a Channel State Information RS (CSI-RS) and a Demodulation RS (DMRS). The CSI-RS is mainly intended for a UE to perform measurements and provide CSI to the gNB. A non-zero power CSI-RS (NZPCSI-RS) resource is used for channel measurements. A CSI-Interference Measurement (CSI-IM) resource associated with the Zero Power CSI-RS (ZPCSI-RS) configuration is used for interference measurement reporting (IMR). The CSI process includes the 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 higher layer signaling. The CSI-RS transmission instance can be indicated by DL control signaling or configured through higher layer signaling. The DM-RS is transmitted only within the BW of each PDCCH or PDSCH, and the UE can demodulate data and control information using the DMRS.

[0072] 4 and 5 illustrate example wireless transmit and receive paths according to the present disclosure. In the following description, transmit path 400 may be described as being implemented within a gNB (such as gNB 102), and receive path 500 may be described as being implemented within a UE (such as UE 116). However, it will be appreciated that receive path 500 may be implemented in a gNB and transmit path 400 may be implemented within a UE. In some embodiments, receive path 500 is configured to support codebook design and construction for systems with 2D antenna arrays, as described in embodiments of the present disclosure.

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

[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), and modulates the input bits (using Quadrature Phase Shift Keying (QPSK) or Quadrature Amplitude Modulation (QAM)) to generate a sequence of frequency-domain modulation symbols.

[0075] The serial-to-parallel block 410 converts the serially modulated symbols into parallel data (e.g., demultiplexing) to generate N parallel symbol streams, where N is the IFFT / FFT size used by the gNB 102 and the UE 116. The size-N IFFT block 415 performs an IFFT operation on the N parallel symbol streams and generates a time-domain output signal. The parallel-to-serial block 420 converts (e.g., multiplexes) the parallel time-domain output symbols from the size-N IFFT block 415 to generate a serial time-domain signal. The cyclic prefix addition block 425 inserts a cyclic prefix into the time-domain signal. The upconverter 430 modulates (e.g., upconverts) the output of the cyclic prefix addition block 425 to an RF frequency (e.g., upconverts) for transmission over a wireless channel. The signal may be baseband filtered before converting to an RF frequency.

[0076] The RF signal transmitted from gNB 102 passes through a wireless channel and reaches UE 116, where the opposite operation to that performed by gNB 102 is performed.

[0077] As shown in FIG. 5, downconverter 555 downconverts the received signal to a baseband frequency, and cyclic prefix removal block 560 removes the cyclic prefix to generate a serial time-domain baseband signal. Serial-to-parallel block 565 converts the time-domain baseband signal to parallel time-domain signals. Size N FFT block 570 performs an FFT algorithm to generate N parallel frequency-domain signals. Parallel-to-serial block 575 converts the parallel frequency-domain signals to a sequence of modulated data symbols. Channel decoding and demodulation block 580 demodulates and decodes the modulated symbols to recover the original input data stream.

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

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

[0080] Also, while the use of FFT and IFFT has been described, 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 the variable N in the DFT and IDFT functions can be any integer (1, 2, 3, 4, etc.), and that the value of the variable N in the FFT and IFFT functions can be any integer that is a power of 2 (1, 2, 4, 8, 16, etc.).

[0081] While Figures 4 and 5 illustrate example wireless transmit and receive paths, various modifications to Figures 4 and 5 are possible. For example, various components in Figures 4 and 5 may be combined, further subdivided, or omitted, and additional components may be added according to particular needs. Also, Figures 4 and 5 illustrate examples of the types of transmit and receive paths that may be used in a wireless network. Any other suitable structure for supporting wireless communication within a wireless network may be used.

[0082] A non-terrestrial network (NTN) refers to a network or a segment of a network that uses RF resources onboard a communications satellite (or unmanned aircraft system platform) (e.g., communications satellite 104). Given its wide coverage and ability to provide stable service, an NTN is expected to ensure universal service availability and continuity. For example, an NTN can support communications services for unserved areas not covered by traditional terrestrial networks, underserved areas with limited communications service, devices and passengers on moving platforms, and future rail, maritime, and aviation communications.

[0083] In NTN, cell movement can occur, leading to inaccuracies in the UE's knowledge of the platform's location and various types of propagation and processing delays within the system. Knowledge of the various delays and predictions associated with the platform satellite almanac data can be used for more accurate estimation of the timing advance (TA), leading to better pre-compensation at the UE.

[0084] 6 illustrates an example of a distance estimation 600 according to one embodiment of the present disclosure. The embodiment of the distance estimation 600 illustrated in FIG. 6 is for illustrative purposes only. FIG. 6 does not limit the scope of the present disclosure to any particular implementation of the distance estimation 600.

[0085] As shown in Figure 6, the UE seeks to estimate its distance from an airborne / satellite-borne platform (such as a satellite). Such distance estimates can then be used to perform any timing pre-distortion at the UE. Such knowledge can be used to determine, report, and use an appropriate timing advance.

[0086] The airborne / satellite-based platform acquires its GNSS-based position at time t1. This information reaches the gNB via the NTN gateway. The gNB places the satellite's (interim transformed position) in the appropriate system information (SI). The UE receives the satellite position at time tN and can compare the satellite's position with its own position at time tN. While FIG. 6 illustrates an airborne / satellite-based platform moving from left to right, such a platform may be fixed relative to a point on the Earth's surface.

[0087] 7 illustrates an example operation 700 of satellite almanac, time, and delay management according to an embodiment of the present disclosure. The embodiment of the example operation 700 of satellite almanac, time, and delay management illustrated in FIG. 7 is for illustrative purposes only. FIG. 7 is a specific implementation of the example operation 700 of satellite almanac, 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 almanac, time, NTN type, component delay, and component measurement values, and transmits information related to transmission, signaling, and / or configuration for the satellite almanac, time, and delay.

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

[0090] As shown in FIG. 8, an airborne / satellite-based platform acquires its position and time and provides the associated satellite almanac information and time to the NTN GW and / or gNB. An entity such as the platform, NTN GW, OAM, and / or user interface provides delay characteristics to the gNB. The gNB communicates the associated delay, time, etc. to the UE using system information. The gNB configures and / or instructs the UE about TA and time reporting via broadcast, groupcast / multicast, RRC, MAC, and / or PHY signaling. The UE adjusts its TA using the information provided by the gNB. The UE reports its 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 report request via system information, groupcast / multicast, RRC, MAC, or PHY signaling, and the UE provides such reports.

[0091] Table 1 identifies examples of various instants and delays in conjunction with one or more embodiments of the present disclosure.

[0092] [Table 1]

[0093] 9 illustrates an example UE-network procedure 900 for managing satellite almanac, time, and delay according to an embodiment of the present disclosure. The embodiment of the example UE-network procedure 900 for managing satellite almanac, time, and delay illustrated in FIG. 9 is for illustrative purposes only. FIG. 9 is a specific implementation of the example UE-network procedure 900 for managing satellite almanac, time, and delay and does not limit the scope of the present disclosure.

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

[0095] In operation F9S2, as an exemplary approach, the platform uses real-time signaling to communicate selected satellite almanac 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 ("epoch") are transmitted by the platform. In yet another embodiment, reference point coordinates (e.g., corresponding to the center of the cell) are also identified by the platform. As another approach, the NTN GW, OAM system, application server, or an entity within or coupled to the gNB can provide the reference point coordinates to the gNB based on the selected satellite almanac data and known satellite beam parameters (e.g., beam coverage) and time. As yet another approach, orbital parameters including time ("epoch") are used to identify the platform's location.

[0096] In operation F9S3, as an exemplary approach, the NTN GW uses knowledge of the history, propagation delay, and processing delay of the selected satellite almanac data to predict and identify the selected satellite almanac data at the intra-cell reference point at the time the UE receives such information from the gNB through the NTN GW and platform. As another alternative, the NTN-GW does not perform such prediction and instead conveys to the gNB the originally selected satellite almanac data and time received from the platform.

[0097] In operation F9S4, as an exemplary approach, the gNB uses knowledge of the history, propagation delays, and processing delays of the selected satellite almanac data to predict and identify the selected satellite almanac data at the intra-cell reference point at the time the UE receives such information from the gNB through the NTN GW and platform. As another alternative, the gNB does not perform such prediction and instead utilizes the original or NTN GW-modified selected satellite almanac data and time.

[0098] In operation F9S5, as an exemplary approach, the gNB identifies one or more instants for an NTN GW for final transmission to the UE, selected satellite almanac data associated with the one or more instants, and reference point location coordinates associated with the one or more instants. In another embodiment of the present disclosure, the gNB identifies location coordinates (also simply referred to as "coordinates" in this disclosure) for one or more NTN GWs. For example, an NTN GW is generally suitable for a given NTN cell until a feeder link transition is required. In an exemplary implementation, the time applicability of an NTN GW for a given UE or set of UEs may also be determined by the gNB and transmitted to the UE by the gNB. In one embodiment of the present disclosure, the gNB configures one or more SIBs to transmit one or more instants, selected satellite almanac data associated with the one or more instants, and reference point location coordinates associated with the one or more instants to the NTN GW and / or NTN-GW location coordinates, so that different information is transmitted at different configured intervals. For example, more long-term or event-based information such as NTN-GW location coordinates may be transmitted less frequently, while more real-time information such as short-term satellite almanac data may be transmitted more frequently. Also, as one exemplary approach, certain system information such as the NTN-GW is transmitted using groupcast / multicast signaling, with a subset of UEs in a cell (and not all UEs in a cell) receiving selected NTN-GW information.

[0099] In operation F9S5, in one embodiment of the present disclosure, the gNB specifies to the UE via broadcast, groupcast / multicast signaling, and / or UE-specific RRC signaling which parameters to use directly and which parameters to estimate to facilitate prefix correction, TA calculation, and TA reporting.

[0100] Examples of time that the gNB may determine include the current time as observed by the gNB, the time provided by the platform (i.e., the point in time when the platform's position was determined / acquired from GNSS), and / or the time provided by the NTN GW, and the expected time of reception of the SIB at the reference point. In embodiments of the present disclosure, the time may also be a complete time (e.g., hours, minutes, seconds, etc.). In other embodiments of the present disclosure, the time may 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 gNB are configured, as part of a configuration signaling exchange or through configuration by an OAM system, server, or user interface, with an indication as to whether an entity (i.e., the platform, the gNB, the NTN GW, or a new entity) will perform the prediction regarding the platform satellite almanac at a future time, along with an identifier regarding the future time, such as one or more of the following: (i) the time when the gNB generates a SIB message, (ii) the time when the NTN GW receives the SIB from the gNB, (iii) the time when the platform receives the SIB, (iv) the time when the cell reference point receives the SIB, and (v) the time when the UE receives the SIB.

[0102] In operation F9S6, as one exemplary approach, the NTN GW transmits one or more times, selected satellite almanac data associated with the one or more times, reference point coordinates associated with the one or more times, and selected delays to the platform, which transmits the information to the UE over the access / service link.

[0103] In operation F9S7, the UE obtains the received time, satellite almanac data, reference point coordinates and delays.

[0104] In operation F9S8, the UE determines an appropriate timing advance as part of precompensation for time (and frequency) adjustment. In an exemplary embodiment of the present disclosure, a specific method of precompensation allows the UE to estimate the time adjustment required for uplink transmission using the time differences (i) between the reference point location and the gNB, and (ii) between the UE location and the gNB. When the periodicity of information updates related to time, satellite almanac data, reference point coordinates, and delays is fast enough to meet accuracy requirements, the UE assumes symmetric gNB-to-UE and UE-to-gNB as an exemplary approach. Another approach assumes asymmetric gNB-to-UE and UE-to-gNB while the UE calculates the timing advance. More specifically, the UE utilizes or predicts the time and satellite almanac data at which the transmission is expected to be received at the gNB.

[0105] In an exemplary embodiment, 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 formula, t_ue_to_platform_adjustment and t_platform_to_gNB_adjustment reflect timing adjustment due to delay asymmetry caused by different positions of the platform (and interim UE) during gNB-to-UE and UE-to-gNB transmissions. In an example 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 formula.

[0108] In operation F9S9, the UE performs uplink transmission using precompensation (e.g., UE autonomous, network assisted, or network directed). In an exemplary embodiment, the gNB uses broadcast or groupcast / multicast signaling to indicate the types of precompensation methods supported or allowed in the cell. Also, in an exemplary embodiment, parameters used by the UE and applicable conditions for the use of such parameters are defined implicitly (e.g., through a standard specification) or explicitly set by the gNB.

[0109] In operation F9S10, as one exemplary approach, the gNB configures the UE with a TA reporting configuration through dedicated RRC signaling. As another exemplary approach, the gNB can broadcast or groupcast / multicast a parameter or indicator for configuring the UE with the relevant TA report. In one embodiment, the gNB can be configured to report a full TA (i.e., a TA that includes the gNB-to-UE delay and the UE-to-gNB delay) to the UE. In another embodiment, the gNB can be configured to report a TA that increases in proportion to the reference point to the UE. In another embodiment, the TA can be specified for a minimum common delay based on the NTN type (e.g., a delay calculated based on the platform type, such as GEO / LEO / HAPS, and the minimum distance between the platform and the UE).

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

[0111] In operation F9S11, the TA report is transmitted via RRC messages (e.g., Measurement Report and RRC Resume) or at a lower layer (e.g., UCI or MAC Control Element) as configured by the gNB.

[0112] For long-term almanac data (i.e., data valid for longer than a few minutes or hours), the network communicates such data to the UE in operation F9S12 using various mechanisms, such as broadcast, groupcast / multicast, or unicast signaling within the NTN, pre-provisioning the UE in the SIM, or non-NTN signaling (e.g., using a conventional cellular or Wi-Fi network). Changes in long-term almanac data can be communicated via the use of valueFlags associated with a particular version of long-term almanac data. As an exemplary approach, the UE looks for new long-term almanac data in the appropriate SIB only when the valueFlag changes. Updated data can be communicated in an incremental manner (i.e., simply changing certain parameters or completely changing the old data). As an exemplary approach, the periodicity of valueFlags, the long-term almanac data, and changes in the long-term almanac data are controlled independently.

[0113] Various methods are possible for the time specified in the above step. In one method, the time is an absolute time (e.g., UTC or gNSS-based time). In another method, to reduce overhead, only more specific times are specified (e.g., minutes and seconds, or seconds), and less specific times are omitted (e.g., hours, or hours and minutes). In yet another method, absolute times are transmitted at regular intervals, or more specific times are transmitted more frequently. In another method, when multiple times are specified in one message, one time is selected as a reference time and is specified as absolute time in all units (e.g., hours, minutes, seconds, etc.) or in a selected unit (e.g., seconds only), and other non-reference times are times that increase relative to the reference time.

[0114] In an example implementation, in addition to the time points involved in gNB-to-UE transmission, the time points involved in UE-to-gNB transmission may also be identified. For example, an appropriate entity (e.g., a gNB, a platform, and an NTN GW, where gNB is a common choice) may identify the time and location of when the UE's signal is expected at the platform, NTN GW, and / or gNB. Such information allows the UE to accurately calculate the UE-to-platform delay and the platform-to-NTN GW delay.

[0115] Various methods are possible for the platform position and velocity determined in the above step. First, the position and velocity may be transmitted at the same or different intervals. For example, the position may be transmitted at one interval and the velocity at another interval. Position and velocity values may not change to the same extent from one point in time to another. Therefore, if a quantity does not change rapidly, the frequency of transmission of that quantity may be reduced. Conversely, if a quantity changes rapidly, that quantity may need to be transmitted more frequently so that the UE's understanding of the platform's position and velocity is accurate. In one method, absolute values are used. In another method, absolute values are transmitted at a certain interval and changing values are transmitted more frequently. In yet another method, when multiple positions and multiple velocities are specified in a single message, one set of values is selected as a reference, and other non-reference values are specified as increasing times relative to the reference time. Furthermore, if a new position is specified but a new velocity is not, the previously determined velocity is used.

[0116] Figure 10 is a flowchart illustrating an example gNB procedure 1000 for supporting satellite almanac and TA management in accordance with one embodiment of the present disclosure. The embodiment of the example gNB procedure 1000 for supporting satellite almanac and TA management illustrated in Figure 10 is for illustrative purposes only. Figure 10 is a specific implementation of the example gNB procedure 1000 for supporting satellite almanac and TA management and does not limit the scope of the present disclosure.

[0117] In operation F10S1, the gNB transmits satellite almanac data with relatively longer time relevance in the system information. Such data may be included in the Release 16 standard SIB or the new SIB for Release 17 or later. Such SIBs are transmitted at a period known to the UE within the cell and may be fixed or configurable. In one exemplary embodiment, the gNB identifies NTN GW coordinates so that the UE can estimate the UE-gNB round trip delay (RTD) or round trip time (RTT). Transmitting NTN GW coordinates is a superior option to transmitting feeder link delays due to higher accuracy and more efficient signaling. Where appropriate, information related to two or more NTN GWs is identified (e.g., to support anticipated NTN GW changes). In operation F10S1 of another embodiment, the gNB determines the total processing delay between the UE and the gNB and reflects the processing delay in both directions, UE-to-gNB and gNB-to-UE. 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 may transmit its 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 the platform to obtain the normal platform and NTN GW processing time. Alternatively, the gNB can obtain such time from OAM or another system. The gNB also obtains or estimates the gNB-NTN-GW transmission delay.

[0119] In operation F10S2, the gNB transmits satellite almanac data with a relatively shorter time relevance in its system information. Such data may be included in the Release 16 standard SIBs or the new SIBs for Release 17 and later. Such SIBs are transmitted at a period known to the UEs in the cell and may be fixed or configurable. In an exemplary embodiment, the gNB transmits selected elements of the satellite almanac data or Earth-Centered Earth-Fixed (ECEF) Cartesian position coordinates (Px, Py, and Pz) and optionally instantaneous velocity (Vx, Vy, and Vz) (derived from the satellite almanac data) more frequently when compared to the information mentioned in operation F10S1.

[0120] In an exemplary embodiment of the present disclosure, absolute values of position and velocity are expressed in one SIB, and incremental values (i.e., values relative to the absolute values) are specified in another SIB in a concise representation to reduce the amount of overhead.

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

[0122] In yet another example, the sensitivity of the position and velocity estimation accuracy is taken into account to determine the size (i.e., number of bytes) of Px, Py, Pz, Vx, Vy, and Vz, in which 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 Equation 1 below to reduce the number of bits in the SIB.

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

[0125] The expected range of (Px, Py, Pz, Vx, Vy, and Vz) is used to determine α and β. In special cases, β can also be 0 and is therefore not used. α and β are either signaled in the SIB or predefined in the specification.

[0126] In an exemplary scheme, α and β, when signaled in the SIB, are transmitted less frequently than the IV, and α and β may be different across (Px, Py, Pz, Vx, Vy, and Vz), or the same α and β may be shared across multiple values.

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

[0128] The information in operations F10S1 and F10S2 is transmitted at a fixed or configurable period (if specified in the SIB), which may be the same as, longer than, or shorter than the 160 ms SIB1 period supported by R16.

[0129] The platform satellite almanac data or position and velocity data identified by the gNB corresponds to the time when the gNB generates the associated SIB. In one embodiment of the present disclosure, such data may correspond to a future time, such as when a UE at the cell center receives such SIB. The UE may become aware of such a moment through a procedure defined in the specification, or the gNB may provide usage instructions for the future time through an appropriate SIB.

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

[0131] In one embodiment of the present disclosure, the gNB broadcasts the cell's reference point coordinates in operation F10S1 or operation F10S2 to allow the UE to estimate the reference point-to-gNB delay. In another embodiment, the UE uses such coordinates to determine the relative TA to report. This information can be used by UEs without timing prefix correction capability, by UEs without GNSS, and by UEs that temporarily lack GNSS visibility. In another embodiment of the present disclosure, the gNB broadcasts a reference point-to-gNB delay that is used by UEs without timing prefix correction capability, by UEs without GNSS, and by UEs that temporarily lack GNSS visibility. Such delay can also be used by the UE to report an incremental TA relative to the reference point's TA.

[0132] In one embodiment of the present disclosure, the gNB includes a value flag in operation F10S1 or operation F10S2 that indicates whether or not long-term NTN data (e.g., a selection element of the platform satellite almanac) has changed, or that prevents unnecessary SI processing in the UE.

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

[0134] If comprehensive long-term platform satellite almanac data is provided to the UE in a file (e.g., on the SIM or via an over-the-air (OTA) update), in one embodiment of the present disclosure, time and coordinates may be represented in a simplified manner to reduce file size, e.g., the overall time and overall coordinates may be specified in a limited number of records in the file, and incremental time and coordinates may be specified in the remaining records in the file.

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

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

[0137] In one embodiment of the present disclosure, the TA report may be asynchronous or request-based, in which case the gNB may 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 another embodiment of the present disclosure, the TA reporting may also be periodic, in which case the gNB sets a TA reporting period for the UE.

[0139] In yet another embodiment of the present disclosure, TA reporting is implicit or rule-based, where the UE transmits the TA when the 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 scheme, the gNB configures such a threshold in the UE. In another exemplary scheme, the threshold is predefined in the specification.

[0140] In one embodiment of the present disclosure, the TA reported is complete (ie, full TA), while in another embodiment, increased TA is reported.

[0141] In yet another embodiment of the present disclosure, the TA (full or incremental) is an index to a table entry, or a formula such as Equation 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.

[0142] One or multiple TA reporting methods may be used simultaneously for a given UE, and one or more TA reporting methods may be mandatory for a supporting UE.

[0143] In operation F10S4, the gNB checks whether asynchronous TA reporting is used. If so, operation F10S5 is performed. If not, operation F10S6 is performed.

[0144] In operation F10S5, the gNB determines whether it needs or desires to transmit an instruction to the UE to obtain an asynchronous or requested TA report. For example, if a long time has passed since the last receipt of a TA report, or if the gNB determines that the UE's UL appears to be out of sync or has fallen out of sync, the gNB may request the UE to transmit a TA report via PHY or MAC signaling.

[0145] In operation F10S6, the gNB checks whether periodic TA reporting is configured for the UE. If not, it proceeds to operation F10S8. If periodic TA reporting is configured, in operation F10S7 the gNB monitors 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 TA adjustments, if necessary. Also, if the timer for periodic TA reports has expired, the timer is restarted against a new TA report.

[0147] In operation F10S8 of the exemplary embodiment, the gNB may receive an indication from the UE that the UE does not currently have GNSS visibility. Such an indication may be specified within the TA report itself in an exemplary manner, where a 1 bit indicates a current lack of GNSS visibility. In other manners, a single TA report value itself (e.g., all 0s, or all 1s, or any other suitable bit pattern) may indicate a lack of GNSS visibility. The gNB may 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 may be received by the gNB via PHY, MAC or RRC signaling, or together with the UL data in an appropriate header.

[0149] In operation F10S8 of another embodiment of the present disclosure, the gNB receives the absence of GNSS visibility indication along with UL data in PHY signaling (e.g., UCI), MAC signaling (e.g., part of MAC CE), or RRC signaling, or an appropriate header. The gNB can then provisionally allow a longer time margin between DL and UL processing in a specific manner of implementation.

[0150] 11 is a flowchart illustrating an example UE procedure 1100 for supporting satellite almanac and TA management in accordance with one embodiment of the present disclosure. The embodiment of the example UE procedure 1100 for supporting satellite almanac and TA management illustrated in FIG. 11 is for illustrative purposes only. FIG. 11 is a specific implementation of the example UE procedure 1100 for supporting satellite almanac 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 almanac through SIM provisioning or NTN (e.g., through a SIB). In an exemplary embodiment of the present disclosure, such data is received by the UE from an application server or OAM system over a terrestrial network (TN), such as a cellular network or a WiFi network. In another embodiment of the present disclosure, if the comprehensive long-term platform satellite almanac data is provided to the UE in a file (e.g., via an over-the-air update on the SIM, TN, or NTN), the time and coordinates may be represented in a simplified manner to reduce the file size. For example, the overall time and overall coordinates may be specified in a limited number of records in the file, and incremental time and coordinates may be specified in the remaining records in the file.

[0152] In operation F11S2, the UE processes one or more SIBs containing satellite almanac data with a relatively long time relevance. Such data may be included in a Release 16 standard SIB or a new SIB for Release 17 or later. Such SIBs are transmitted at a period known to the UE within the cell and may be fixed or configurable. In one exemplary embodiment, the UE estimates the UE-gNB RTD or RTT using the NTN-GW coordinates (see equation E2 below). In operation F11S2 of another embodiment, the UE receives a 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 with relatively short time relevance through system information. Such data may be included in the standard SIBs for Release 16 or new SIBs for Release 17 or later. Such SIBs are transmitted at a period known to the UE in the cell and may be fixed or configured. In an exemplary embodiment, the UE receives selected elements of satellite almanac data or Earth-Centered Earth-Fixed (ECEF) Cartesian position coordinates (Px, Py, and Pz) (derived from the satellite almanac data) and optionally instantaneous velocity (Vx, Vy, and Vz) more frequently than the information mentioned in operation F11S2. If applicable, the UE obtains one or more of (Px, Py, Pz, Vx, Vy, and Vz) using formulas defined in the specification, such as Equation 1. In another exemplary scheme, the UE utilizes one or more tables defined in the standard to express the relationship between TV and IV for the given numbers in Equation 1.

[0154] In an exemplary embodiment of the present disclosure, the UE performs a predictive estimate of the platform's current position and / or velocity by taking into account the difference between the time when such information is relevant and the time when such information is used by the UE. For example, the UE may perform linear or nonlinear extrapolation to more accurately estimate the platform's position and velocity at the time when such information is needed.

[0155] In one embodiment of the present disclosure, if the gNB broadcasts the cell's reference point coordinates in operation F11S1 or operation F11S3, the UE uses the reference point coordinates to estimate the reference point-to-gNB delay when needed. In another embodiment, the UE uses the reference point coordinates to determine the relative TA for TA reporting. This information can be used by UEs without timing precorrection capability, by UEs without GNSS, and by UEs that temporarily lack GNSS visibility. In another embodiment of the present disclosure, if the gNB broadcasts the reference point-to-gNB delay, UEs without timing precorrection capability, UEs without GNSS, and UEs that temporarily lack GNSS visibility can use such delay for timing precorrection. Such delay can also be used by the UE to report an incremental TA relative to the reference point's TA.

[0156] In operation F11S2 or operation F11S3, if the gNB includes a value flag indicating whether or not the long-term NTN data (e.g., a selection element of the platform satellite almanac) has changed, the UE uses the flag to determine whether to acquire the 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 the long-term NTN data. Conversely, if the value flags do not match, the UE performs additional system information processing to acquire new long-term NTN data.

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

[0158] In FIG. 11, actions F11S1, F11S2, and F11S3 relate to platform almanac, and actions F11S4 through F11S10 relate to TA management.

[0159] In operation F10S3, according to an exemplary embodiment of the present disclosure, the UE obtains a TA report 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 TA reporting is configured as asynchronous or ordered, the UE expects to receive a PHY indication (e.g., DCI) or MAC indication (e.g., MAC CE) from the gNB for TA reporting.

[0161] In another embodiment of the present disclosure, if the UE is configured for periodic reporting of TA, the UE receives the periodicity of the TA report.

[0162] In yet another embodiment of the present disclosure, TA reporting is implicit or rule-based, where the UE is expected to transmit a TA when the TA change (i.e., the difference between a previously reported TA and a currently estimated TA) exceeds a threshold, in which case, according to an exemplary scheme, the UE receives such a threshold from the gNB.

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

[0164] In yet another embodiment of the present disclosure, the TA (full or incremental) is an index to a table entry, or a formula such as Equation 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 multiple TA reporting methods may be used simultaneously for a given UE, and one or more TA reporting methods may be mandatory for a supporting UE.

[0166] In operation F11S5, the UE checks whether asynchronous TA reporting has been configured by the gNB. If so, operation F11S6 is performed. If not, operation F11S7 is performed.

[0167] In operation F11S6, the UE checks whether it has sent an instruction for asynchronous or solicited TA reporting. If the UE has received such an instruction from the gNB, it sends a TA report to the gNB and proceeds to operation F11S7.

[0168] In operation F11S7, the UE checks whether periodic TA reporting has been configured by the gNB. If not, the UE proceeds to operation F11S9. If configured, the UE monitors the periodic timer value in operation F11S8, and if the timer expires, the UE transmits a TA report to the gNB and resets the periodic timer before proceeding to operation F11S9.

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

[0170] In operation F11S10, the UE transmits a "GNSS unavailable" indication to the gNB and then 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 taking the TA command into account and then proceeds to operation F11S1.

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

[0173] Figure 12 illustrates a proposed structure 1200 for supporting management of time, almanac, and other aspects of an NTN, according to one embodiment of the present disclosure. The embodiment of the proposed structure 1200 for supporting management of time, almanac, and other aspects of an NTN illustrated in Figure 12 is for illustrative purposes only. Figure 12 is a specific implementation of the proposed structure 1200 for supporting management of time, almanac, and other aspects of an NTN and does not limit the scope of the present disclosure.

[0174] The architecture shown in Figure 12 is suitable for transparent payloads and integrated gNBs, which combine the functions of a gNB-distributed unit (gNB-DU) and a gNB-central unit (gNB-CU).

[0175] The UE may be provided with short-term and long-term NTN data using one of one or more network functions and access networks (eg, cellular access or WiFi access or NTN).

[0176] In FIG. 12, the network platform (NP) is an NTN entity orbiting Earth (e.g., a satellite) or in flight (e.g., a HAPS). The network infrastructure (NI) consists of the NTN platform and NTN GW. The NTN infrastructure controller (NIC) is an implementation-specific controller for the NTN infrastructure (e.g., satellite / HAPS and NTN GW). It is a substitute for the NI and interface with a conventional 5G network function (NF). It exchanges long-term delay-insensitive information with the appropriate 5G NF. For example, the NIC provides the IP address and location (latitude, longitude) of the NTN GW to the gNB or gNB-NTN. The NIC obtains platform-related information through the NTN GW. The application server (AS) provides long-term NTN data, such as a long-term satellite almanac, to the NTN UE via a wired or wireless connection. For example, such data may be stored in a universal subscriber identity module (USIM) or in the UE's memory, as appropriate. The gNB-NTN is a logical function option within 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 satellite (position, velocity, and time) vectors, with the NTN-GW. The gNB-NTN also exchanges long-term data, such as selected orbital parameters and NTN-GW specifications or processing information, with the NTN-GW or NIC. The NTN-GW specifications include whether or not the platform provides changes to the (P, V, T) parameters.

[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 waveforms received within the cell from all NTN UEs or transmitted within the cell.

[0178] The eNTN-GW implements the functionality of a conventional NTN-GW and supports NR baseband signals instead of NRRF signals. By utilizing an optical fiber-based wired interface instead of a wireless interface, protocols such as eCPRI can be used between the gNB and the eNTN-GW for increased stability.

[0179] The transmission of CP signaling and NR-specific signals (e.g., RF or baseband signals) between the NTN-GW (or eNTN-GW) and the gNB (or gNB-NTN) will initially be implementation-specific (i.e., beyond the scope of 3GPP) and may be open for future use depending on 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 containing (P, V, T) parameters, and (ii) the NR-Uu waveform received within the cell from all UEs or transmitted within the cell.

[0181] In general, the following connections may be wired connections (e.g., optical fiber in IP networks or metro Ethernet networks) or wireless connections (e.g., using microwave dish antennas): (i) Nnic-ntn-gw, (ii) NgNB-nic, (iii) NgNB-ntn-gw, (iv) Nnic-mgmt.

[0182] The gNB-DU may or may not be co-located with the NTN-GW / eNTN-GW.

[0183] Figure 13 illustrates a proposed structure 1300 for supporting management of time, almanac, and other aspects of an NTN, according to one embodiment of the present disclosure. The embodiment of the proposed structure 1300 for supporting management of time, almanac, and other aspects of an NTN illustrated in Figure 13 is for illustrative purposes only. Figure 13 is a specific implementation of the proposed structure 1300 for supporting management of time, almanac, and other aspects of an NTN and does not limit the scope of the present disclosure.

[0184] The structure shown in Figure 13 is suitable for a transparent payload and a fragmented gNB. The fragmented gNB has two separate entities, gNB-DU and gNB-CU.

[0185] In an exemplary embodiment of the present disclosure, information related to 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, which may be the NTN platform, NTN-GW, NTN controller, OAM, or application server. As an exemplary approach, the power transmitted by the platform may be used by the gNB so that the gNB knows what to broadcast through the SIB.

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

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

[0188] In one embodiment of the present disclosure, in the cases specified above, the UE utilizes 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-specific UE-gNB delay, the UE can add an offset when such timer starts or when an 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 location estimates the UE-gNB delay using delay information broadcast by the gNB for the three cases described above. Details regarding "delay information" are provided below.

[0189] In one approach, the delay information includes a gNB-estimated gNB-to-reference point delay, where the reference point delay may correspond to the delay between the gNB and an average location (e.g., the cell center). In another approach, the reference point corresponds to a location within the cell with the smallest propagation delay. A one-way delay or round-trip delay is specified by the gNB.

[0190] In one exemplary approach, the delay includes only propagation delay. In another approach, the delay is a total delay including one or more of processing delays (e.g., NTN platform processing and NTN-GW processing) and transmission delays (e.g., NTN-GW-gNB transmission delays). In an exemplary embodiment of the present disclosure, the gNB can indicate the type of delay it is broadcasting.

[0191] Yet another approach splits the delay into multiple parts, such as service link delay, feeder link delay, and (optionally) other delays (e.g., processing + transmission delay). In such cases, a UE without accurate / reliable GNSS-based location can estimate the service link delay using an explicit service link delay (if broadcast by the gNB) or the coordinates of a reference point (e.g., the cell center or a point associated with 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 coordinates to enable the UE to estimate the feeder link delay.

[0193] In an exemplary embodiment of the present disclosure, when the GNSS-based position of the UE 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 associated SI.

[0194] In an exemplary embodiment of the present disclosure, a UE indicates the reliability of its location accuracy quantitatively or qualitatively when reporting its location to the network. For example, the UE may indicate that no GNSS is currently visible. The UE may indicate that its location corresponds to its last known GNSS-based location.

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

[0196] [Formula E1] UE-gNB Total Delay = “UE-specific UE-platform propagation delay” + “Common platform-NTN-GW propagation delay” + “Total Processing Delay”

[0197] In Equation E1, the UE-specific UE-platform propagation delay is estimated by the UE based on the platform coordinates broadcast by the gNB through SI and its own GNSS-based location. As an exemplary approach, the distance I between the UE and the platform is calculated as 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 platform-NTN-GW propagation delay" (also referred to as "feeder link delay") may be broadcast by the gNB through the SI according to the exemplary approach. In another approach, the NTN-GW coordinates (or, alternatively, the gNB coordinates) and the platform coordinates are used to determine the propagation delay between the platform and the NTN-GW instead of the feeder link delay, which varies over time.

[0199] In Equation E1, the "Total Processing Delay" is the sum of: (i) The combination of two or more of the minimum or normal processing delays at the platform, NTN-GW, and gNB; and (ii) NTN-GW-gNB transmission delay, which may be specified as part of the minimum performance specifications, basic assumptions, or 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] [Formula E2] UE-gNBRTT=2*UE-gNB Total Delay

[0202] In other embodiments of the present disclosure, if the UE does not have prefix correction capability, or GNSS is currently unavailable (or a threshold time of X ms has elapsed since an accurate GNSS-based position became available), or if the UE does not have GNSS capability, the UE may estimate the UE-gNB total delay using the following equation E3:

[0203] [Formula E3]

[0204] UE-gNB 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 suitable point on the geographical area where the cell beam is irradiated) and the platform.

[0206] In an exemplary approach, "Total Processing Delay" may be set to 0 in equation E3.

[0207] Additional Embodiments for TA Reporting

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

[0209] In another embodiment of the present disclosure, when a UE receives a TA reporting configuration through RRC signaling, such configuration (including whether TA reporting is enabled or disabled) supersedes any TA reporting indicator that the UE received through a SIB.

[0210] In another embodiment 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 configuration, including enable / disable for the TA report feedback indicator, if such an indicator is received implicitly (e.g., through the presence or absence of an 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 reporting configuration is specified by the gNB through a SIB (e.g., an improved SIB for NTN or a new NTN SIB) in operation F9S6, saving radio resources involved in specifying the TA reporting configuration via dedicated signaling to many UEs in operation F9S10.

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

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

[0214] According to yet another approach, equal priority is given to MAC CEs containing TA reports and MAC CEs containing power headroom reports, and the UE selects whether to transmit any MAC CEs to the gNB. According to another exemplary approach, the UE prioritizes transmission of MAC CEs containing power headroom reports over TA reporting MAC CEs if its power headroom is below a threshold (e.g., phrReportingThreshold).

[0215] In another embodiment of the present disclosure, conventional cell reselection methods are not suitable for NTNs with different types of beams, especially due to satellite movement and the RSRPs of serving and neighboring cells being very similar. Therefore, a new approach is needed for NTNs to improve the stability of cell reselection.

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

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

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

[0219] As shown 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 to save power, if applicable. The UE evaluates the trigger combination and performs cell reselection if the appropriate conditions are met.

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

[0221] In operation F16S1, the gNB / eNB acquires a configuration including a beam type for each cell. According to one processing method, the beam types are classified into three 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 geostationary orbit has an Earth-fixed beam that always covers the same geographical area. A satellite in non-geostationary orbit (e.g., LEO and MEO) may have an Earth-moving beam that moves continuously and covers different geographical areas at different times based on the continuity. A satellite in non-geostationary orbit may have a quasi-Earth-fixed beam that covers a given geographical area for a certain time and covers a different geographical area for a different time.

[0222] In operation F16S2, in an exemplary embodiment of the present disclosure, the gNB / eNB transmits one or more parameters through system information to enable the UE to save some processing power and perform robust 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 a combined trigger that supports cell reselection. In an exemplary implementation, disable-s-IntraSearchP indicates whether the UE should use or ignore the broadcast value of s-IntraSearchP to determine whether it needs to perform measurements on neighbor cells. As another approach, disable-s-IntraSearchP indicates whether the UE should use the broadcast values of s-IntraSearchP and IntraSearchQ to determine whether it needs to perform measurements on neighbor cells. In one embodiment, the timer neighborSearchTimerCellReselection indicates a period during which the UE can skip measuring neighbor 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 parameters disable-s-IntraSearchP and neighborSearchTimerCellReselection to (i) enable the UE to detect neighbors even when the serving cell RSRP is strong, and (ii) avoid measuring neighbor cells to save battery life after cell reselection is performed. In an example embodiment, the gNB / eNB implicitly or explicitly specifies a combined trigger, allowing the UE to evaluate cell reselection trigger conditions. For details of the combined trigger, please refer to the related content of FIG. 19.

[0223] Another approach is to use the "S rxlev > S IntraSerachP and S qual > S IntraSerachQThe disable effect can be achieved by selecting an appropriate value of s-IntraSearchP (e.g., a high value of s-IntraSearchP) within the specified range so that the UE searches for a neighbor even when the condition of "S" is not satisfied and the serving cell signal measurement value (e.g., RSRP) is not good. rxlev > S IntraSerachP and S qual > S IntraSerachQ To ensure that the condition "is not satisfied," s-IntraSearchQ may not be present in the system information in one approach, and s-IntraSearchP may be the sole determinant of the condition. As another approach, an appropriate value of s-IntraSearchQ within the specified range (e.g., a high value of s-IntraSearchQ) may be selected.

[0224] In operation F16S3, the UE determines when to perform cell reselection, which involves performing measurements on neighbor cells, using received parameters such as Disable-s-IntraSearchP, neighborSearchTimerCellReselection, and parameters related to the combined trigger.

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

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

[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 for a given NTN). In an exemplary implementation, the gNB / eNB may transmit this parameter in SIB2, which transmits the normal s-IntraSearchP. In another implementation, the gNB / eNB transmits disable-s-IntraSearchP through a SIB other than SIB2. For example, a new SIB defined for the NTN may transmit disable-s-IntraSearchP.

[0228] In operation F17S3, the gNB / eNB transmits parameters related to a combining trigger supporting cell reselection and (if necessary) neighborSearchTimerCellReselection through a new SIB that may be specifically defined for the 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 implicitly or explicitly specifies the combining trigger, allowing the UE to evaluate the cell reselection trigger conditions. For details of the combining trigger, please refer to the related content of FIG. 19.

[0229] In operation F17S4, which is the same as operation F16S3, the UE uses received parameters such as Disable-s-IntraSearchP, neighborSearchTimerCellReselection and parameters related to the combined trigger to determine whether to perform measurements on neighbor cells and when to perform cell reselection.

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

[0231] In operation F18S1 (same as operations F16S1 and F17S1), the gNB / eNB acquires a configuration including a beam type for each cell. According to one processing method, the beam types are classified into three 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 geostationary orbit has an Earth-fixed beam that always covers the same geographical area. A satellite in non-geostationary orbit (e.g., LEO and MEO) may have an Earth-moving beam that moves continuously and covers different geographical areas at different times based on the continuity. A satellite in non-geostationary orbit may have a quasi-Earth-fixed beam that covers a given geographical area for a certain time and covers another geographical area for a different time.

[0232] In operation F18S2 (similar to operation F16S2 of FIG. 16 or a combination of operations F17S2 and F17S3 of FIG. 17), in an exemplary embodiment of the present disclosure, the gNB / eNB transmits one or more parameters through system information to enable the UE to save some processing power and perform robust 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 a combined trigger that supports cell reselection. For details of the combined trigger, see the related content of FIG. 19.

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

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

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

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

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

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

[0239] As an exemplary approach, the gNB / eNB can define two trigger conditions (i.e., N=2) for quasi-Earth-Fixed beams—Trigger Condition 1 and Trigger Condition 2. To define Trigger Condition 1, the gNB specifies TSLCR and NCSM as individual triggers and specifies a logical OR function to combine TSLCR and NCSM. To define Trigger Condition 2, the gNB specifies neighbor serving cell signal measurement (NSCSM) as a trigger combination rather than just an individual trigger (thus, any logical combination function is not required in this example). The exemplary approach described herein can be extended to any suitable number of trigger conditions and any suitable number of individual triggers for a given trigger combination. Additionally, a satellite-mobile-based offset can be applied by the gNB / eNB to the neighbor cell-based individual trigger (which is part of the combined trigger).

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

[0241] In yet another exemplary approach, the set of all trigger conditions (together with associated combinations 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 system information, and the UE then utilizes the applicable conditions based on the beam type.

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

[0243] In operation F19S3, the UE performs measurements on the quantities specified in the triggers and evaluates available conditions 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 appropriate for different types of beams. Individual triggers and trigger combinations for cell reselection within the NTN are identified below.

[0246] One-way propagation delay (OPDSC) to the serving cell as a trigger. The one-way propagation delay (OPD) between the NTN platform (e.g., satellite or HAPS) and the UE can be used as an indirect indicator of the distance between the NTN platform and the UE. If the OPD is larger than 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 a combined trigger in the trigger condition. The UE can estimate the gNB-to-UE delay by (i) observing the time difference between when the SIB containing the timestamp is received at the UE and when the SIB containing the timestamp is generated by the gNB. The UE can then calculate the OPDSC by subtracting the gNB-to-the-platform delay (e.g., total feeder link delay) from the gNB-to-UE delay. The OPDSC can serve as a useful trigger for Earth-fixed and Earth-moving beams. In an exemplary embodiment of the present disclosure, the gNB / eNB broadcasts Threshold_PropagationDelayServingCell_CellReselection through system information.

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

[0248] One trigger is the distance to the platform in the serving cell (DTPSC). The distance between the NTN platform and the UE in the serving cell can be used as a trigger. If 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 fixed-Earth beam case). For example, "if (DTPSC>Threshold_Distance_ServingCell_CellReselection)" can be used as part of a combined trigger in the trigger condition. A GNSS-capable UE can estimate the distance to the platform using its own GNSS position received through system information. This distance can serve as a useful trigger for Earth-fixed beams. In an exemplary embodiment of the present disclosure, the gNB / eNB broadcasts TThreshold_Distance_ServingCell_CellReselection through system information.

[0249] Time Since Last Cell Reselection (TSLCR) as a trigger. The time elapsed since the last cell reselection can be used as a trigger (e.g., in the case of a quasi-Earth-Fixed beam). For example, "if (TSLCR>Threshold_Time_CellReselection)" can be used as part of a combined trigger in the trigger condition. The UE initiates or restarts TSLCR when performing cell reselection to a new cell. In an exemplary embodiment of the present disclosure, the gNB / eNB broadcasts Threshold_Time_CellReselection through system information.

[0250] The TSLCR approach corresponds to a quasi-Earth-Fixed beam (i.e., fixed beam relative to LEO) approach expressed in terms of the serving or dwell time of a cell in a given geographic area. Using an absolute time stamp as a trigger is yet another approach that corresponds to the TSLCR approach.

[0251] 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 in a trigger condition. In such an expression, when the satellite of the NTN cell is directly overhead, the elevation angle is 90° and increases as the NTN cell or beam continues to move farther away from the UE. In an exemplary embodiment of the present disclosure, the gNB / eNB broadcasts hreshold_ServingElevationAngle_NTN through system information. In an exemplary embodiment of the present disclosure, the gNB / eNB broadcasts hreshold_ServingElevationAngle_NTN through system information.

[0252] Adjacent Cell Elevation Angle (NCEA) as a trigger. The elevation angle of an adjacent cell can be used as a trigger for cell reselection. A large NCEA means that the UE is near the boundary of the adjacent 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 an adjacent cell can be utilized as a trigger for cell reselection. A small ASMD means that the UE is near the boundary of the adjacent 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. Neighbor cell signal measurements may be used as a trigger for cell reselection. Strong NCSM means that the UE has a satisfactory radio environment with the neighboring cell. For example, "if (NCSM>Threshold_SignalMesurement_Neighbor_NTN) for timeToTrigger" may be used as part of a combined trigger in the trigger condition. timeToTrigger may be set to 0. Exemplary signal measurements include RSRP, RSRQ, and SINR. In an exemplary embodiment of the present disclosure, the gNB / eNB broadcasts Threshold_SignalMesurement_Neighbor_NTN through system information.

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

[0256] Individual adjacent cell trigger improvements

[0257] In an exemplary embodiment of the present disclosure, satellite motion-based offsets may be added with the non-signal measurement neighbor cell trigger quantities (e.g., elevation angle, distance, and propagation delay) described above to encourage or discourage cell reselection to a given neighbor cell. For example, a positive offset may be used to encourage an incoming neighbor cell to reselect to a given neighbor cell. A zero offset neither encourages nor discourages cell reselection to the neighbor cell. A negative offset may be used to discourage an outgoing neighbor cell from reselecting to a given neighbor cell.

[0258] Depending on the position of the offset within the equation defining the trigger condition, the offset may be opposite, e.g., a positive offset may be used to discourage cell reselection and prevent cell reselection to a neighboring cell.

[0259] In another possible embodiment, to prevent cell reselection to neighbor cells not specified in the neighbor list, the UE may be prohibited from evaluating neighbor cells not in the neighbor list for cell reselection and handover purposes. According to an exemplary approach, neighbor cells not listed in the neighbor list may be continuously searched for and measured to support self-organizing network (SON) functionality and Minimized Drive Test (MDT).

[0260] According to an exemplary approach, the basic trigger 'if(triggerQuantityForANeighbor>Threshold_TriggerQuantity)' can be modified to 'if((triggerQuantityForANeighbor+Δ)>Threshold_TriggerQuantity)' to reflect the satellite mobile infrastructure offset Δ. According to an exemplary approach, in a given cell, the gNB / eNB broadcasts a Δ value for the target neighbor cell.

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

[0262] In an exemplary implementation, when a UE performs a search for a neighboring cell not mentioned in the system information, as an exemplary approach, a base offset (e.g., a negative offset) may be defined and broadcast by the gNB / eNB to prevent cell reselection to such a neighboring cell. In another implementation, the base value may be explicitly defined in the specification.

[0263] Combined Triggers and Trigger Conditions

[0264] In terrestrial networks (TNs), RSRP and RSRQ-based cell reselection are commonly used. However, in NTNs, signal measurements such as RSRP are similar for both the serving cell and neighboring cells. Therefore, to improve the stability of the cell reselection procedure, multiple triggers, including those specific to NTNs, are combined.

[0265] In one embodiment of the present disclosure, previously defined individual quantity-based sub-trigger triggers (ie, individual triggers) are combined in a flexible manner to generate multiple 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 conjunction function to generate a combined trigger ("Trigger A") as follows:

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

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

[0269] Such a combined trigger "A" is suitable for terrestrial mobile beams. The use of satellite-based neighbor lists prevents inaccurate cell reselection (i.e., cell reselection to neighbor cells that are moving far 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, and the second part of the combined trigger indicates that the neighboring cell provides the UE with a suitable radio environment for communication.

[0271] In one embodiment of the present disclosure, the individual triggers "DTPSC Trigger" and "NCSM Trigger" are combined using a conjunction 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 ["If((NSM+Δ)>Threshold_SignalMesurement_Neighbor_NTN) for timeToTrigger"], cell reselection is triggered and the neighbor cell selection procedure is performed.

[0274] Such a combined trigger "B" is suitable for terrestrial mobile beams. The use of satellite-based neighbor lists prevents inaccurate cell reselection (i.e., cell reselection to neighbor cells that are moving far 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, and the second part of the combined trigger indicates that the neighboring cell provides the UE with a suitable radio environment for communication.

[0276] Combination trigger "B" is even more direct than combination trigger "A" in that it utilizes distance itself instead of propagation delay, which is a proxy for distance.

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

[0278] For one of the neighboring cells, [“if(TSLCR>Threshold_Time_CellReselection)”] AND

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

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

[0281] The first part of the combination trigger "C" indicates that sufficient time has passed since the last time cell reselection was performed and that a neighboring cell suitable for cell reselection is soon to be reached, and the second part of the combination trigger indicates that the neighboring cell can provide the UE with a suitable radio environment for communication.

[0282] Combination trigger "C" is also useful for UEs without gNSS capabilities.

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

[0284] For one of the neighboring cells, [“if(SCEA>Threshold_ServingElevationAngle_NTN)”] AND

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

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

[0287] The first part of the combination 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, and the second part of the combination trigger indicates that the neighboring cell can provide the UE with a suitable radio environment for communication.

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

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

[0290] If ["If((NSM+Δ)>Threshold_SignalMesurement_Neighbor_NTN) for timeToTrigger"], cell reselection is triggered and the neighbor cell selection procedure is performed.

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

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

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

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

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

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

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

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

[0299] In one embodiment of the present disclosure, "ASMD Trigger" is used as a special case, not combined with other individual triggers, to generate a combination trigger ("trigger G").

[0300] If the condition for any one of the neighboring cells is met ("If((ASMD<)for timeToTrigger"), cell reselection is triggered and the neighboring cell selection procedure is performed. To prevent frequency cell reselection due to the UE satisfying the same trigger condition "G" within a short period of time, 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 a satellite-mobile based neighbor list prevents inaccurate cell reselection (i.e., cell reselection to a neighbor cell that is moving far from the UE).

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

[0303] In one embodiment of the present disclosure, "NSCSM Trigger" is used as a special case, not combined with other individual triggers, to generate a combination trigger ("Trigger H").

[0304] If the condition for any one of the neighbor cells is [“if((NCSM-SCSM)>Threshold_SignalMesurement_Serving_Neighbor_NTN) for timeToTrigger”], cell reselection is triggered and the neighbor cell selection procedure is performed.

[0305] This combined trigger "H" is suitable for Earth-Fixed Beams, quasi-Earth-Fixed beams and Earth-Moving Beams. The use of a satellite-mobile based neighbor list prevents inaccurate cell reselection (i.e., cell reselection to a neighbor cell that is moving far from the UE).

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

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

[0308] In an exemplary embodiment of the present disclosure, cell reselection is triggered when one or more of the triggering conditions are satisfied for any neighboring cell. This implies the use of a logical OR function to combine different triggering conditions. In other embodiments of the present disclosure, a logical AND function can be used to combine multiple triggering conditions to make a cell reselection decision.

[0309] In one exemplary approach, the neighboring cells that the UE evaluates for triggering conditions are explicitly identified through system information. In another exemplary approach, the neighboring cells that the UE evaluates for triggering conditions are autonomously detected by the UE and are not explicitly identified through system information.

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

[0311] "Neighbor cell selection" method

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

[0313] In an exemplary embodiment of the present disclosure, the cell ranking criteria Rs for the serving cell and Rn for the neighboring cells are calculated taking into account the satellite mobile infrastructure offset: 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, reselection is performed to the neighbor cell with the highest rank Rn by not considering Rs and setting Δ to 0.

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

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

[0318] In another exemplary embodiment of the present disclosure, the cell ranking criterion R for a neighboring cell is calculated taking into account the satellite-mobile base offset and the number of trigger conditions satisfied by the neighboring cell (herein referred to as numTriggerConditions), where α is an incentive for satisfying the trigger conditions identified by the gNB / eNB through system information: 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 met, reselection is performed to the neighbor cell with the highest rank Rn without considering Rs.

[0321] In another approach, each trigger condition can have its own weight value α.

[0322] Signalling of satellite mobile infrastructure parameters

[0323] In one embodiment of the present disclosure, a satellite mobile infrastructure offset is determined for each neighbor cell in operations F16S2, F18S2 and / or F19S2.

[0324] In another embodiment of the present disclosure, to reduce overhead in operations F7S2, F8S2, F9S2 and / or F10S2, a satellite mobile infrastructure offset is identified for each set of neighbor cells.

[0325] In yet another embodiment of the present disclosure, the type of neighboring cell is indicated based on the movement of the neighboring cell using one or more of the following names for the quasi-earth fixed beam: "Incoming Neighbor," "Current Geographic Neighbor," and "Incoming Overlapping Neighbor." The name "Incoming Neighbor" means that the neighboring cell is a geographic neighbor of a cell that can provide nearly identical overlapping coverage to the current serving cell. The name "Current Geographic Neighbor" means that the neighboring cell is a geographic neighbor of the current serving cell. The name "Incoming Overlapping Neighbor" means that the neighboring cell is a cell that can provide nearly identical overlapping coverage to the current serving cell.

[0326] Such neighbor cell names can be used by the UE to prioritize neighbor selection of a given type for quasi-earth fixed beams.

[0327] As an exemplary approach, neighbor name specific coefficients are used with a given threshold β to implement prioritization as expressed in the following equation: Rn = Q meas,n - Qoffset - Qoffset temp + C * β

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

[0329] The parameter β is used to avoid ping-pong during cell reselection, and the coefficient c is used to set different priorities for different types of cells. For example, c can be set to 3 if (i) neighboring cell n is an Incoming Overlapping Neighbor, 2 if neighboring cell n is an Incoming Neighbor, or 1 if neighboring cell n is a Current Geographic Neighbor. Larger positive values of c prioritize neighboring cell selection, while smaller positive values of c lower the priority for neighboring cell selection.

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

[0331] In another embodiment of the present disclosure, the type of neighbor cell is indicated based on the movement of the neighbor cell using one or more of the following names for the Earth mobile beam: "Incoming Neighbor," "Neutral Neighbor," and "Outgoing Neighbor." The name "Incoming Neighbor" means that the beam of the neighbor cell is moving toward the geographical area currently served by the serving cell, and the design intent is to encourage cell reselection to such a neighbor cell. The name "Neutral Neighbor" means that cell reselection to such a neighbor cell is neither encouraged nor inhibited in terms of beam movement. The name "Outgoing Neighbor" means that the beam of the neighbor cell is moving away from the geographical area currently served by the serving cell, and the design intent is to prevent cell reselection to such a neighbor cell.

[0332] Such neighbor cell names may be used by the UE to prioritize neighbor selection of a given type for an Earth moving beam.

[0333] As an exemplary approach, neighbor name specific coefficients are used with a given threshold γ to implement the prioritization as expressed in 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. For example, d is set to '1' (i) if neighboring cell 'n' is an 'Incoming Neighbor', (ii) '0' if neighboring cell 'n' is a 'Neutral Neighbor', or (iii) '-1' if neighboring cell 'n' is an 'Outgoing Neighbor'. A positive (or larger positive) value of d prioritizes neighboring cell selection, while a negative value of d lowers the priority for neighboring cell selection.

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

[0337] Additional standalone / individual and combination triggers

[0338] Inner Area (IA) as a Trigger. Because the coverage of satellite beams 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. For Earth-fixed and Earth-moving beams, the UE can use the criterion "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 to perform cell reselection. If the UE is outside the IA, this indicates that the UE may search for a suitable neighboring cell within the adjacent overlap area (i.e., the boundary between two or more cells) for cell reselection. The UE can use its location (e.g., latitude and longitude) along with the center, major axis (or semimajor axis), and minor axis (or semiminor axis) of the elliptical area to determine whether it is inside or outside the IA.

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

[0340] The UE determines whether to use the IA (or above it) or an implementation-specific 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 semimajor radius), and minor axis (or semiminor radius) of its beam's elliptical region in operations F16S2, F17S2, F18S2, and / or F19S2. As an exemplary approach, a single inner-region trigger is combined with one or more of the previously identified single triggers to generate a combined trigger for cell reselection.

[0342] In one embodiment of the present disclosure, the individual triggers "Inner Area Trigger" and "NCSM Trigger" are combined using a conjunction function to generate a combined trigger ("Trigger I") as follows:

[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 neighbor cell selection procedure is performed.

[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 combination 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, and the second part of the combination trigger indicates that the neighboring cell can provide the UE with a suitable radio environment for communication.

[0347] In one embodiment of the present disclosure, the individual triggers "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] [“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 neighbor cell selection procedure is performed.

[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 combination 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, while the last or third part of the combination trigger indicates that the neighboring cell can provide the UE with a suitable radio environment for communication.

[0353] In one embodiment of the present disclosure, the individual triggers "Serving Cell RSRP / RSRQ Trigger" and "NCSM Trigger" are combined using a logical AND function to generate a combined trigger ("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 neighbor cell selection procedure is performed.

[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 combination 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, and the second part of the combination trigger indicates that the neighboring cell can provide the UE with a suitable radio environment for communication.

[0358] Serving cell center-UE distance (SCCUD) as one trigger. The UE calculates the distance between itself and the center of the serving cell 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 the UE may find a suitable neighboring cell for cell reselection within the neighbor overlap area (i.e., the boundary between 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, the 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, the individual triggers "SCCUD Trigger" and "NCSM Trigger" are combined using a conjunction function to create a combined trigger ("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 neighbor cell selection procedure is performed.

[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 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, and the second part of the combined trigger indicates that the neighboring cell can provide the UE with a suitable radio environment for communication.

[0365] In one embodiment of the present disclosure, the individual triggers "RSRP / RSRQ Trigger", "SCCUD Trigger" and "NCSM Trigger" are combined using a conjunction 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 neighbor cell selection procedure is performed.

[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 that the UE is far from the center of the serving cell and close to the serving cell boundary, indicating the need for cell reselection, while the third or last part of the combined trigger indicates that a neighboring cell can provide the UE with a suitable radio environment for communication.

[0371] Remaining Serving Time (RST) as one 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 low, the UE triggers cell reselection.

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

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

[0374] For one of the neighboring cells, [“If remainingServingTime < remainingServingTimeThreshold”)] AND

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

[0376] This combination trigger "n" is suitable for quasi-Earth fixed beams and moving Earth beams, and for feeder link switches for quasi-Earth fixed beams and moving Earth beams.

[0377] The first part of the combination trigger "n" indicates the need for cell reselection, and the second part of the combination trigger indicates that the neighboring cell can provide the UE with a suitable radio environment for communication.

[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 to a fallback neighbor cell.

[0380] This combination trigger "O" is suitable for quasi-earth-fixed beams and for feeder link switches for earth-fixed and earth-moving beams.

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

[0382] In another embodiment, 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, the UE performs cell reselection to a fallback neighboring cell when cell reselection is not triggered by any condition other than trigger "O." As another approach, the UE performs cell reselection to a fallback neighboring cell when no neighboring cell has a better rank than the current serving cell. Cell reselection to a fallback neighboring cell is performed when the condition for trigger "O" is 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 to a fallback neighbor cell. The variable dwellTime is the elapsed time after cell selection or reselection to the current serving cell, and maxServingTimeThreshold specifies the maximum period for which an Earth moving beam covers a given point on the Earth representation area.

[0386] Such a combined trigger "P" is suitable for moving earth beams.

[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 neighbor cell.

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

[0389] Figure 20 is a flowchart illustrating a method 2000 of operating a UE, such as UE 116, that may be performed by a UE in accordance with an embodiment of the present disclosure. The embodiment of method 2000 illustrated in Figure 20 is for illustrative purposes only. Figure 20 does not limit the scope of the present disclosure to any particular implementation.

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

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

[0392] In 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 when a condition is met or random access is performed, transmits a timing advance report periodically, or transmits a timing advance report upon command from the BS.

[0394] In one embodiment, the UE sends the 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 almanac data, and changes in the long term satellite almanac data are communicated via flags.

[0396] In one embodiment, the UE receives the location and velocity data included in the system information in 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 neighboring cells.

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

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

[0400] Figure 21 is a flow chart illustrating another method 2100 that may be performed by a BS, such as BS 102, in accordance with an embodiment of the present disclosure. The embodiment of method 2100 illustrated in Figure 21 is for illustrative purposes only. Figure 21 does not limit the scope of the present disclosure to any particular implementation.

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

[0402] In operation 2104, the BS transmits 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 a timing difference between the reference point position and the base station.

[0404] In one embodiment, the BS automatically receives a timing advance report when a condition is met or random access is performed, receives a timing advance report periodically, or receives a timing advance report upon command from the BS.

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

[0406] In one embodiment, the system information includes long term satellite almanac data, and changes in the long term satellite almanac data are communicated via flags.

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

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

[0409] In one embodiment, the system information includes neighbor cell selection information that indicates that an input cell is to be preferred over an output cell.

[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 inner area of the serving cell, and when an indication that the user equipment (UE) is outside the inner area of the serving cell is received and the signal measurement value of the neighboring cell satisfies a threshold, a measurement report is received or the neighboring cell is selected as the serving cell.

[0411] The flowcharts illustrate example methods that may be implemented in accordance with the principles of the present disclosure, and various modifications may be made to the methods depicted in the flowcharts. For example, although a series of acts are depicted, in each figure, various acts may overlap, occur in parallel, occur in a different order, or occur multiple times. In other examples, acts may be omitted or replaced with other acts.

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

[0413] 22, a base station 2000 includes a processor 2210, a transceiver 2220, and a memory 2230. However, none of the components shown in the figure are required. The base station 2000 may be implemented with more or fewer components than those shown in FIG. 22. Furthermore, the processor 2210, the transceiver 2220, and the memory 2230 may be implemented as a single chip in other embodiments.

[0414] In an exemplary embodiment, the base station 2000 is also a gNodeB (gNB). In an exemplary embodiment, the above-mentioned gNB 101, gNB 102, and gNB 103 may correspond to the base station 2000.

[0415] The above mentioned components are described in more detail below.

[0416] The processor 2210 may include one or more processors or other processing devices that control the functions, processes, and / or methods described herein. The operations of the base station 2000 may be implemented by the processor 2210.

[0417] The transceiver 2220 includes an RF transmitter for upconverting and amplifying signals to be transmitted, and an RF receiver for downconverting the frequency of received signals, although in other embodiments the transceiver 2220 may be embodied with more or fewer components than those shown.

[0418] The transceiver 2220 is coupled to the processor 2210 and may transmit and / or receive signals. The signals may include control information and data. The transceiver 2220 may also receive signals over a wireless channel and output the signals to the processor 2210. The transceiver 2220 may transmit signals output from the processor 2210 over a wireless channel.

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

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

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

[0422] For example, UEs 111-116 shown in FIG.

[0423] The above mentioned components are described in detail below.

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

[0425] The transceiver 2320 includes an RF transmitter for upconverting and amplifying signals to be transmitted, and an RF receiver for downconverting the frequency of received signals, although in other embodiments the transceiver 2320 may be embodied with more or fewer components than those shown.

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

[0427] The memory 2330 may store control information or data included in signals obtained by the UE 2300. The memory 2330 may be coupled to the processor 2310 and may store at least one instruction, protocol, or parameter related to proposed functions, processes, and / or methods. The memory 2330 may include a read-only memory (ROM), a random access memory (RAM), a hard disk, a CD-ROM, a DVD, and / or other storage devices.

[0428] Although the present invention has been described with exemplary embodiments, various changes and modifications may be suggested to those skilled in the art. The present disclosure is intended to include such changes and modifications that fall within the scope of the claims. Nothing in this application should be construed as implying that any particular element, act, or function is essential to be included in the claims. The patentable scope of the present invention is limited by the claims. [Explanation of symbols]

[0429] 2210 processor 2220 Transmitter / Receiver 2230 memory 2310 processor 2320 Transmitter / Receiver 2330 memory

Claims

1. A method performed by a user equipment (UE), comprising: receiving configuration information from a base station; determining a timing advance (TA) based on the UE location and the configuration information; If a difference between the TA and a previously reported TA exceeds a threshold, transmitting a TA report to the base station via a MAC medium access control element (CE).

2. The configuration information is received via a system information block (SIB), The method of claim 1 , wherein the configuration information provides satellite ephemeris.

3. The method of claim 1 , wherein the threshold is received via a radio resource control (RRC) message.

4. The TA is determined based on a sum of a UE-specific value and a common value; The UE-specific value is determined based on the UE location and satellite orbit information included in the configuration information; The method of claim 1 , wherein the common value is determined based on the configuration information.

5. 1. A method performed by a base station, comprising: transmitting configuration information to a user equipment (UE); receiving a TA report from the UE via a MAC medium access control element (CE) if a difference between the TA and a previously reported TA exceeds a threshold; The method, wherein the TA is determined based on a UE location and the configuration information.

6. The configuration information is transmitted via a system information block (SIB), The method of claim 5 , wherein the configuration information provides satellite ephemeris.

7. The TA is determined based on a sum of a UE-specific value and a common value; The UE-specific value is determined based on the UE location and satellite orbit information included in the configuration information; The method of claim 5 , wherein the common value is determined based on the configuration information.

8. In a UE (user equipment), at least one transceiver; at least one processor communicatively coupled to the at least one transceiver; a memory communicatively coupled to the at least one processor and storing one or more instructions; The one or more instructions, when individually or collectively executed by the at least one processor, cause the UE to: receiving setting information from the base station; determining a timing advance (TA) based on the UE location and the configuration information; If the difference between the TA and the previously reported TA exceeds a threshold, the UE transmits a TA report to the base station via a MAC medium access control element (CE).

9. The configuration information is received via a system information block (SIB), The UE of claim 8 , wherein the configuration information provides satellite ephemeris.

10. The UE of claim 8 , wherein the threshold is received via a radio resource control (RRC) message.

11. The TA is determined based on a sum of a UE-specific value and a common value; The UE-specific value is determined based on the UE location and satellite orbit information included in the configuration information; The UE of claim 8 , wherein the common value is determined based on the configuration information.

12. In the base station, at least one transceiver; at least one processor communicatively coupled to the at least one transceiver; a memory communicatively coupled to the at least one processor and storing one or more instructions; The one or more instructions, when individually or collectively executed by the at least one processor, cause the base station to: Sending configuration information to a UE (user equipment); If the difference between the timing advance (TA) and the previously reported TA exceeds a threshold, a TA report is received from the UE via a MAC medium access control (CE); The base station determines the TA based on the UE location and the configuration information.

13. The configuration information is transmitted via a system information block (SIB), The base station of claim 12, wherein the configuration information provides satellite ephemeris.

14. The base station of claim 12 , wherein the threshold is transmitted via a radio resource control (RRC) message.

15. The TA is determined based on a sum of a UE-specific value and a common value; The UE-specific value is determined based on the UE location and satellite orbit information included in the configuration information; The base station according to claim 12 , wherein the common value is determined based on the configuration information.

Images