Method and apparatus for performing timing advance adjustment between a UE and a non-terrestrial network

Abstract

A method and apparatus for performing timing advance adjustment between a user equipment (UE) and a non-terrestrial network (NTN), the method comprising: receiving and decoding a media access control (MAC) control element (CE) including closed-loop information; receiving and decoding system information including open-loop information; determining a timing advance value based on the closed-loop information or the open-loop information; and controlling the timing of an uplink transmission signal transmitted from the UE based on the timing advance value.

Description

[0001] This application claims priority to U.S. Provisional Patent Application Serial No. 63 / 225,076, filed Jul. 23, 2021, U.S. Provisional Patent Application Serial No. 63 / 182,477, filed Apr. 30, 2021, and U.S. Non-Provisional Patent Application Serial No. 17 / 711,550, filed Apr. 1, 2022, the entire contents of which are hereby incorporated by reference. Field of the Invention

[0002] The present disclosure generally relates to improving wireless communication for non-terrestrial networks (NTN). Background of the Invention

[0003] In a wireless communication system, a timing advance (TA) may be calculated to account for propagation delay. Since NTN often requires transmitting signals over particularly long distances (e.g., from the Earth to a satellite) and the propagation delay is thus longer, it is particularly important for new radio (NR) NTN user equipment (UE) to calculate an accurate TA.

[0004] The TA applied by an NR NTN UE in the RRC_CONNECTED state may include two components, namely an open-loop component (e.g., when the TA is autonomously estimated by the UE) and a closed-loop component (e.g., when the TA command is provided by the network). Since, for example, the resulting TA should be based on the latest uplink transmission and is prone to timeout, adding the closed-loop TA component provided by the network (e.g., received from a gNB) to the open-loop TA component that has already been autonomously estimated by the UE may result in an inaccurate TA value. Additionally, due to the estimation error that the UE may have for the open-loop TA component, the UE's autonomous TA estimation may be incorrect. Moreover, even when both the closed-loop TA component and the open-loop TA component are accurate, applying these two components may erroneously result in double correction, and thus the resulting TA command is insufficient to perform satisfactory wireless communication.

[0005] Accordingly, a solution is needed to combine closed-loop TA updates and open-loop TA updates to achieve improved TA timing estimation.

[0006] In addition, NTN may be required to support UE mobility at speeds up to 1,200 kilometers per hour (km / h). In addition, Low Earth Orbit (LEO) satellites can travel at speeds up to 7.4 kilometers per second (s). For LEO satellites, even if the coverage area size of a beam is 1,000 km, it only takes about 2 minutes for a UE to switch from one beam to another beam. In a more practical scenario, the coverage area size of an LEO satellite beam may be much smaller than 1,000 km, so the dwell time for a UE to stay in a beam and then switch to another beam may be much shorter than 2 minutes. However, satellite movement (including speed and / or direction) can be accurately predicted. The predictability of satellite movement can be used to assist faster beam switching with a smaller amount of signaling.

[0007] Therefore, a solution is also needed to develop NR specifications to support effectively configured beam and Bandwidth Part (BWP) switching. Summary of the Invention

[0008] This disclosure has been made to solve the above problems and disadvantages and at least provide the advantages described below.

[0009] According to an aspect of the present disclosure, a method for performing timing advance adjustment between a UE and NTN includes: receiving and decoding a Media Access Control (MAC) Control Element (CE) including closed-loop information; receiving and decoding system information including open-loop information; determining a timing advance value based on the closed-loop information or the open-loop information; and controlling the timing of an uplink transmission signal transmitted from the UE based on the timing advance value.

[0010] According to another aspect of the present disclosure, a UE is provided. The UE includes: a memory; and a processor configured to: receive and decode a MAC CE including closed-loop information; receive and decode system information including open-loop information; determine a timing advance value based on the closed-loop information or the open-loop information; and control the timing of an uplink transmission signal transmitted from the UE based on the timing advance value. Brief Description of the Drawings

[0011] The above and other aspects, features, and advantages of specific embodiments of the present disclosure will become more apparent from the following detailed description in conjunction with the accompanying drawings, in which:

[0012] Figure 1 is a diagram showing signaling between a UE, a satellite, and a gNB according to an embodiment;

[0013] Figure 2 shows a satellite operating frequency band divided into 3 equal BWPs according to an embodiment;

[0014] Figure 3Shows a configuration where 7 satellite beams are assigned to 3 BWPs according to an embodiment;

[0015] Figure 4 Is a timing diagram showing the closed-loop priority for TA commands according to an embodiment;

[0016] Figure 5 Is a timing diagram showing the open-loop priority for TA commands according to an embodiment;

[0017] Figure 6 Shows a flowchart for closed-loop priority configuration and open-loop priority configuration according to an embodiment;

[0018] Figure 7 Shows a configuration where 7 satellite beams are assigned to 3 BWPs according to an embodiment;

[0019] Figure 8 Shows a configuration where 7 satellite beams are assigned to 3 BWPs according to an embodiment;

[0020] Figure 9 Shows a configuration for broadcasting beam information to the network according to an embodiment;

[0021] Figure 10 Shows a flowchart of a group beam / BWP switching method according to an embodiment; and

[0022] Figure 11 Shows an electronic device in a network environment according to an embodiment. Detailed Description of the Invention

[0023] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. Although the same or similar elements are shown in different drawings, the same or similar elements may be represented by the same reference numerals.

[0024] In the following description, only specific details (such as detailed configurations and components) are provided to assist in a comprehensive understanding of the embodiments of the present disclosure. Therefore, it will be apparent to those skilled in the art that various changes and modifications can be made to the embodiments described herein without departing from the scope of the present disclosure.

[0025] In addition, descriptions of well-known functions and structures are omitted for clarity and conciseness.

[0026] The terms described below are terms defined in consideration of the functions in the present disclosure and may vary according to the user, the user's intention, or custom. Therefore, the definitions of the terms should be determined based on the content throughout this specification.

[0027] The present disclosure may have various modifications and various embodiments, and embodiments in various embodiments will be described in detail below with reference to the accompanying drawings. However, it should be understood that the present disclosure is not limited to the embodiments, but includes all modifications, equivalents, and alternatives within the scope of the present disclosure.

[0028] Although terms including ordinal numbers (such as first, second, etc.) may be used to describe various elements, the structural elements are not limited by these terms. These terms are only used to distinguish one element from another. For example, without departing from the scope of the present disclosure, a first structural element may be referred to as a second structural element. Similarly, a second structural element may also be referred to as a first structural element. As used herein, the term "and / or" includes any and all combinations of one or more related items.

[0029] The terms used herein are only for describing various embodiments of the present disclosure and are not intended to limit the present disclosure. Unless otherwise clearly specified in the context, the singular form is intended to include the plural form. In the present disclosure, the term "comprising" or "having" indicates the presence of features, numbers, steps, operations, structural elements, components, or combinations thereof, and does not exclude the presence of one or more other features, numbers, steps, operations, structural elements, components, or combinations thereof or the possibility of adding one or more other features, numbers, steps, operations, structural elements, components, or combinations thereof.

[0030] Unless otherwise defined, all terms used herein have the same meaning as understood by those skilled in the art to which the present disclosure belongs. Terms such as those defined in commonly used dictionaries should be interpreted as having the same meaning as the context in the relevant field, and should not be interpreted as having an ideal or overly formal meaning unless clearly defined in the present disclosure.

[0031] An electronic device according to an embodiment may be one of various types of electronic devices. The electronic device may include, for example, a portable communication device (e.g., a smart phone), a computer, a portable multimedia device, a portable medical device, a camera, a wearable device, or a household appliance. According to an embodiment of the present disclosure, the electronic device is not limited to the above embodiments.

[0032] As used herein, each of the phrases such as "A or B", "at least one of A and B", "at least one of A or B", "A, B, or C", "at least one of A, B, and C", and "at least one of A, B, or C" can include all possible combinations of the items listed together in the respective one of the phrases. Terms such as "first", "second", "first", and "second" may be used to distinguish the corresponding components from another component, but are not intended to limit these components in other respects (e.g., importance or order). If an element (e.g., a first element) is referred to as "coupled to", "coupled to another element (e.g., a second element)", "connected to", or "connected to another element (e.g., a second element)" with or without the terms "operatively" or "communicatively", it indicates that the element can be coupled to the other element directly (e.g., wired), wirelessly, or via a third element.

[0033] As used herein, the term "module" may include a unit implemented in hardware, software, or firmware, and may be used interchangeably with other terms such as "logic", "logic block", "part", and "circuit". A module may be a single integrated component or its smallest unit or part adapted to perform one or more functions. For example, according to one embodiment, a module may be implemented in the form of an application specific integrated circuit (ASIC).

[0034] The present disclosure proposes to provide TA updates for combining open-loop TA components and closed-loop TA components based on priority configuration. Additionally, the present disclosure proposes beam / BWP switching based on network-initiated configuration, UE-initiated configuration, conditional beam / BWP switching, and group beam / BWP switching.

[0035] The present disclosure provides an intelligent combination of open-loop TA components and closed-loop TA components to avoid double correction of TA. Additionally, the present disclosure proposes to use the predictability of satellite movement to assist faster beam switching, which is more efficient and requires less signaling than found in existing systems.

[0036] TA can be used to control the uplink transmission timing of an individual UE and synchronize the uplink transmissions of all UEs belonging to the network. In the fifth generation (5G) NR, TA is first adjusted during the initial access and random access procedures based on the TA command field in msg2 and msgB during the 4-step and 2-step random access channel (RACH) procedures, respectively. Later, TA updates in the RRC_CONNECTED state can be performed through closed-loop operation based on the TA command field in the MAC CE TA command.

[0037] To control the uplink transmission timing, the UE may receive a first TA command in msg2 / msgB. A 12-bit set may be used to provide values in the range from 0 to 3846. This value corresponds to T A and, where T A can be used to calculate N according to the following equation (1) TA .

[0038] N TA = T A × 16 × 64 / 2 μ

[0039] … Equation (1)

[0040] After initial access, when a TA command is provided in the MAC CE to update the TA, T A is a 6-bit field providing a value range from 0 to 63. This TA command is used to dynamically update the existing TA. The TA command provided during the random access procedure may be an absolute TA, while the subsequent TA commands provided in the MAC CE may be relative. The value of N TA can be updated according to the following equation (2).

[0041] N TA，new = N TA，old + (T A - 31) × 16 × 64 / 2 μ

[0042] … Equation (2)

[0043] In Equation (2), T A is the TA command field received in the MAC CE command.

[0044] The TA applied by the UE can be calculated according to the following equation (3).

[0045] T TA = (N TA + N TA，offset ) × T c

[0046] … Equation (3)

[0047] In Equation (3), T c = 1 (480,000 × 4096). It can be specified to include N TA，offset to ensure that the uplink radio frame ends before the start of the subsequent downlink radio frame. The TA command may be sent on a per-need basis, and the granularity in the step size may be 0.52 microseconds (μs).

[0048] In NR NTN, TA updates in the RRC_CONNECTED state may experience extreme variations in propagation delay and TA command timeouts.

[0049] Regarding extreme variations in propagation delay, in NTN, the radial velocity between the satellite and UE positions can reach significant values, especially for LEO and Medium Earth Orbit (MEO) satellites. As a result, the propagation delay can rapidly vary over a wide range of values. For example, in the case of a LEO satellite transparent payload at an altitude of 600 kilometers (km), the maximum NTN gateway (GW)-UE delay variation seen by the UE can be as high as ±40 μs / second (sec). Under such conditions, performing maintenance procedures based on MAC CE may become challenging because the downlink signaling overhead increases due to the frequent transmission of user-specific timing adjustment MAC CE commands.

[0050] Regarding TA command timeouts, even ignoring the issue of downlink MAC CE signaling overload when the TA command reaches the UE as discussed above, the TA command may still timeout. For example, in the case of a LEO satellite scenario at an altitude of 1200 km, for a one-way delay of 20.89 milliseconds (ms), the accurate TA command sent by the gNB at the time of TA command transmission may timeout by 0.83 μs when it arrives. This is greater than the cyclic prefix (CP) duration of 0.59 μs for a 120 kHz subcarrier spacing (SCS). Therefore, data loss may occur due to the possible timeout of the TA command.

[0051] Figure 1 is a diagram showing signaling between a UE, a satellite, and a gateway according to an embodiment.

[0052] Referring to Figure 1 , a network including a UE 101, a satellite 102, and a gateway 103 (e.g., gNB) is provided. The satellite is shown at a first position at time T1 and at a second position at time T2. Additionally, two signal paths are shown for the UE 101 to wirelessly communicate with the gateway 103 via the satellite 102. The first signal path includes the signals shown at time T s1 and T f1 shown. The second signal path includes the signals shown at time T s2 and T f2 shown. The signal in the first signal path is sent from the gateway 103 to the UE101 (or from the UE 101 to the gateway 103) at time T1, and the signal in the second signal path is sent from the UE 101 to the gateway 103 (or from the gateway 103 to the UE 101) at time T2. The difference in the total time taken to transmit the signal in the first signal path and the signal in the second signal path is referred to as the delay variation and can be expressed as 2x|(Ts1 +T F1 )-(T s2 +T f2 )(For example, as described above, the maximum NTN GW-UE delay variation with a LEO satellite transparent payload at an altitude of 600 km can be up to ±40 μs / sec).

[0053] To address the propagation delay variation in the NTN network, the TA applied by an NR NTN UE in the RRC_CONNECTED state can be given according to Equation (4) below.

[0054] T TA =(N TA +N TA，UE-specific +N TA，common +N TA，offset )×T c

[0055] …Equation (4)

[0056] In Equation (4), for the Physical Random Access Channel (PRACH), N TA is defined as 0 and is updated based on the TA command field in msg2 / msgB and the MAC CE TA command. As defined in Equation (3) above, N TA，UE-specific is the UE self-estimated TA value for pre-compensating the serving link delay. N TA，common is the network-controlled common TA and can include any timing offset that the network deems necessary (e.g., an N TA，common value of "0" can be supported), and N TA，offset is a fixed offset for calculating the TA.

[0057] In Equation (4), to determine the TA update, the UE should update N TA based on a closed-loop mechanism and update (N TA，UE-specific +N TA，common ) based on an open-loop mechanism.

[0058] To update N TA in the RRC_CONNECTED state, the NR NTN can reuse the NR mechanism based on the TA command field in msg2 / msgB and the MAC CE TA command without specific changes. Since this mechanism is based on the TA command received by the UE from the network, this mechanism can be called a closed-loop.

[0059] Now, the update of (N TA，UE-specific +N TA，common ) based on the open-loop mechanism will be described.

[0060] Since this mechanism is based on UE-specific calculations and / or estimations using information sent from the network to the UE, this mechanism can be referred to as open-loop. Especially in the case of non-geostationary (NGEO) satellite scenarios, the necessity of open-loop TA updates may be related to the high round-trip delay (RTD) drifts on both the serving link and the feeder link. For such scenarios, using only closed-loop may not be sufficient to update the TA. By utilizing open-loop based TA updates, the UE can autonomously track the RTD changes on the serving link and the feeder link to keep the residual timing error within the maximum tolerable range that the CP can absorb.

[0061] In the RRC_CONNECTED state, the NR NTN UE should update T TA such that the CP can absorb the propagation delay changes caused by the movements of both the satellite and the UE. By using open-loop TA updates, the UE can compensate for the delay so that the residual delay can be absorbed by the CP in use. The general rule for the UE to maintain timing synchronization with the gNB is that the timing drift between the UE and the gNB should be within ±(CP-channel delay spread) / 2.

[0062] In the following discussion, without loss of generality, since the channel delay spread can be less than the CP in typical NTN scenarios, the channel delay spread is considered negligible.

[0063] Accordingly, it can be inferred that for a 15 kilohertz (kHz) SCS with a CP of 4.69 μs, the UE should estimate the TA within ±2.34 μs, or equivalently, the UE should estimate the distance to a reference point (e.g., the gNB) within ±704 meters (m) (=±2.34 μs × speed of light (c) in free space). Similarly, for a 120 kHz SCS with a CP of 0.59 μs, the UE should estimate the TA within ±0.29 μs or equivalently estimate the distance from the UE to the reference point within ±88 m.

[0064] In addition, if the updated common TA-related auxiliary information is available at the UE during the last 0.7 seconds when indicating the common TA drift rate to the UE, or during the last 5 seconds when indicating both the common TA drift rate and the common drift change rate to the UE, the UE can autonomously predict and correct the common delay N TA，common 。

[0065] Furthermore, if the updated satellite ephemeris data is available at the UE during the last 45 seconds, the UE can also autonomously predict and correct the delay on the serving link within a timing error range of 0.15 μs.

[0066] Therefore, by updating N TA，UE-specific +N TA，connon, the UE can autonomously track the RTD changes on the serving link and feeder link to keep the residual timing error within the maximum tolerable range that can be absorbed by the CP for the worst case of 120 kHz SCS (i.e., 0.59 μs).

[0067] Beam / BWP switching will now be described.

[0068] Frequency division multiplexing (FDM) allocation for each satellite beam may be the most effective way to avoid inter-beam interference. To complete the FDM allocation for each satellite beam, adjacent beams can be assigned to different center frequencies. In other words, a frequency reuse factor (FRF) greater than 1 should be used to reduce inter-beam interference and increase the signal-to-interference-plus-noise ratio (SINR). For example, an FRF of 3 or a combination of an FRF of 2 and polarization reuse can provide a satisfactory SINR for all NTN scenarios. To achieve an FRF greater than 1 in the NTN network, the concept of BWP can be used. In the BWP method, the total operating band of the satellite can be divided into multiple non-overlapping BWPs.

[0069] Figure 2 Fig. shows a satellite operating band divided into 3 equal BWPs according to an embodiment.

[0070] Referring to Figure 2 , BWP#1, BPW#2, and BWP#3 are shown configured in the satellite operating band. Additionally, there can be up to 4 configured BWPs (i.e., BWP#1, BWP#2, BWP#3, and BWP#4) indexed from 1 to 4. The bandwidths of the BWPs do not necessarily have to be equal and can be configured with different bandwidths according to the load of each beam.

[0071] Figure 3 Fig. shows a configuration in which 7 satellite beams are allocated to 3 BWPs according to an embodiment.

[0072] Referring to Figure 3 , each beam transmitted from satellite 301 is allocated to a BWP such that adjacent beams are allocated to separate BWPs. That is, beam #1 is allocated to BWP#3, beam #2 is allocated to BWP#2, beam #3 is allocated to BWP#3, beam #4 is allocated to BWP#2, beam #5 is allocated to BWP#3, beam #6 is allocated to BWP#2, and beam #7 is allocated to BWP#3. Beams #1 - #7 can be included in a single cell. Since the BWPs basically do not overlap, inter-beam interference can be mitigated. The mapping assignment between the beam and the BWP is part of the beam planning and is determined by the network designer. Although Figure 3 Fig. shows an example in which 7 satellite beams are allocated to 3 BWPs, but other variations are also possible.

[0073] Beam management and beam switching will now be described.

[0074] For NR, the beam management procedure can select the best beam for the UE. For beam selection, the UE can measure the synchronization signal block (SSB) or non-zero power (NZP)-channel state information (CSI)-reference signal (RS) (NZP-CSI-RS) of the serving beam and adjacent beams, and report the measurement results to the gNB.

[0075] Based on the reported measurements, the gNB can select the best serving beam for the UE. The gNB can indicate the serving beam to the UE via downlink control information (DCI) or the transmission configuration indicator (TCI) state on the MAC CE. The TCI state can include fields for the cell index, BWP index, SSB index, and CSI-RS for a specific control resource set (CORESET). For the physical downlink control channel (PDCCH), the MAC CE can be used to activate one of a set of TCI states that have been configured for each CORESET using RRC signaling. Otherwise (i.e., in the case where the TCI field in the DCI is not configured), for the physical downlink shared channel (PDSCH), the DCI in the PDCCH can be used to indicate its TCI state, and the TCI state of the PDSCH will follow the PDCCH TCI state.

[0076] BWP switching will now be described.

[0077] The gNB can dynamically switch the active BWP using the BWP indicator field within DCI formats 0_1 and 1_1. The BWP indicator field in the DCI can indicate to the UE which BWP the frequency domain resource allocation is located in. The switching process from one BWP index to another may not be instantaneous, so the gNB may not be able to allocate resources immediately after switching the BWP. The switching delay can be specified by 5G NR. The UE can be configured with a default downlink BWP. If the UE is configured with a bwp-inactive timer, the UE switches back to the default BWP after the bwp-inactive timer expires when using a non-default BWP.

[0078] 5G NR does not specify the association between the beam index and the BWP index. In NTN, in the case where the beam and the BWP are associated with each other, the network should consider switching the beam and switching the BWP for the UE as two separate tasks, even if they occur simultaneously when the UE moves from one beam to another due to the satellite or the movement of the UE.

[0079] NTN may be required to support UE mobility at speeds up to 1200 kilometers per hour (km / h). Additionally, LEO satellites can travel at speeds up to 7.4 km / s. For LEO satellites, even if the coverage area size of a beam is 1000 km, a UE may take only about 2 minutes to switch from one beam to another. In a more practical scenario, the coverage area size of an LEO satellite beam may be much less than 1000 km, so the dwell time for a UE to stay in a beam and then switch to another beam may be much shorter than 2 minutes. However, satellite movement (speed and direction) is precisely predictable. The network may be able to determine the position of the satellite and may also be able to predict the position of the satellite in the near future. Ephemeris information of the satellite can also be indicated to the UE so that the UE can predict the position of the satellite.

[0080] If the network and / or the UE also know the topology of the satellite beam, beam switching is predictable for the network and / or the UE. However, frequent beam switching may come at the cost of significant signaling and possible delays and latencies in the network, which may be too costly. Since satellite beam switching can be frequent and highly predictable, it is beneficial to reduce redundant signaling overhead and latency if the target beam and switching conditions are pre-configured for the UE. The predictability of satellite movement can be utilized to help with faster beam switching with a reduced amount of signaling. Accordingly, the present disclosure provides a solution for configured beam and BWP switching.

[0081] In addition, as mentioned above, the TA applied by an NR NTN UE in the RRC_CONNECTED state can be given by Equation (4) above. Equation (4) consists of two components (i.e., open-loop and closed-loop). Equation (4) provides the following general guidance: for TA updates in the RRC_CONNECTED state, the combination of the open control loop (i.e., UE autonomous TA estimation N TA，UE-specific and common TA estimation N TA，common ) and the closed control loop (i.e., received TA command) should be supported for NR NTN.

[0082] Adding the closed-loop TA command update received from the gNB to the open-loop TA value already autonomously estimated by the UE may result in an inaccurate TA value. For example, the resulting TA value may wrongly cause double correction. Additionally, the TA command can be based on the latest uplink transmission and may be prone to timeout. On the other hand, the UE's autonomous TA estimation may also be incorrect because the estimation error that the UE may have for the self-estimated TA component (e.g., open-loop component) may be too large.

[0083] Therefore, it is necessary to combine closed-loop TA updates and open-loop TA updates to achieve accurate and precise TA timing estimation.

[0084] In NTN, there are several different scenarios where different combinations may be needed for how to combine the closed-loop component and the open-loop component. The scenarios can vary based on RTD and satellite speed. Therefore, according to embodiments of the present disclosure, a flexible solution that can be used for different scenarios is provided.

[0085] For a geostationary (GEO) satellite scenario, the satellite can have an orbital period equal to the Earth's rotation period and thus appears stationary at a fixed position in the sky to a ground observer. For example, the maximum distance between the satellite and the user equipment at the minimum elevation angle can be 40,581 km. This means that for a transparent satellite, the maximum RTD will be 541.46 ms. In a transparent satellite, the gNB and the gateway can be located on the ground and the satellite can receive signals from the gateway, convert the carrier frequency, and filter and amplify the signals before sending them back to the ground on the downlink.

[0086] The GEO satellite scenario can support UE movement of up to 1200 km / h on Earth. This means that by the time the UE receives a closed-loop TA command, the UE may have been repositioned by ±180 meters (m), which is equivalent to a timing of ±0.6 μs. Therefore, for a 15 kHz SCS with a TA error tolerance of ±2.34 μs, the TA command will be satisfactory and there is no need to perform open-loop TA estimation. However, for a 120 kHz SCS with a TA error tolerance of ±0.29 μs, the TA command is not sufficient to compensate for the TA and open-loop TA estimation will be required.

[0087] For LEO and MEO satellite scenarios, closed-loop estimation and open-loop estimation may be required. For example, in the case of a LEO satellite scenario at 1200 km, for a maximum RTD of 41.77 ms, the TA command sent by the gNB may time out by 1.66 μs when it arrives. This is much greater than the TA error tolerance of ±0.29 μs for a 120 kHz SCS.

[0088] According to an embodiment, the network can configure the UE to preferentially use closed-loop TA updates or open-loop TA updates. That is, in some cases (e.g., when the closed-loop method is prioritized), the closed-loop method can be used instead of the open-loop method (using N TA , and not using N TA，UE-specific +N TA，common ). In other cases (e.g., when the open-loop method is prioritized), the open-loop method can be used instead of the closed-loop method (using N TA，UE-specific +N TA，common , and not using N TA ).

[0089] The method is flexible enough to support different scenarios with different RTDs and different UE mobility characteristics. Priority can be given to either the open-loop or the closed-loop, and a timer can be set by the UE. The priority can be pre-configured or configured by the network. Additionally, the timer can be configured by the network. These configurations can be done via dedicated or common RRC signaling (e.g., using SIB).

[0090] The UE can use either the open-loop method or the closed-loop method based on the configured priority. However, if the information required for the corresponding method is not available within a given time, the UE can revert (or switch) to another method. The time the UE waits before reverting to another method can be configured by the network.

[0091] Figure 4 is a timing diagram showing the closed-loop priority of TA commands according to an embodiment.

[0092] Referring to Figure 4 , if the UE is configured with a priority for the closed-loop method but does not receive a TA command for the closed-loop within the configured time “TAC-valid timer”, the UE can no longer use the closed-loop method and start using the open-loop method.

[0093] For example, the TAC-valid timer can be set to a predetermined time value (e.g., 20 μs). Whenever the UE receives a TA command, the TAC-valid timer can be started by the UE. If the UE does not receive a TA command within the time value of the TAC-valid timer (e.g., 20 μs), the timer will have expired and the UE can start using the open-loop method.

[0094] Figure 5 is a timing diagram showing the open-loop priority for TA commands according to an embodiment.

[0095] Referring to Figure 5 , if the UE is using the open-loop method and the update for N TA，common is unavailable, the satellite ephemeris data is unavailable and / or the internal Global Navigation Satellite System (GNSS) signal of the UE (e.g., Global Positioning System (GPS) signal) fails, the UE may not be able to autonomously estimate the TA. In this case, the OL-valid timer can be restarted based on the open-loop information. The open-loop information can include satellite ephemeris data (e.g., satellite positioning information), UE positioning information, and / or valid N TA，common among others. Additionally, the open-loop information can be stored on the UE and updated periodically by the UE itself (e.g., using the UE positioning information is updated) or by the network (e.g., using the satellite positioning information and / or N TA，common is updated). After the timer OL-valid timer expires, the UE can revert to the closed-loop method.

[0096] The priority configuration and each timer configuration can be done by RRC configuration or reconfiguration or by using MAC CE commands. It can be configured for all UEs within a cell (cell-specific) or can be configured for each individual UE (UE-specific).

[0097] Figure 6 A flowchart showing closed-loop and open-loop priority configuration methods according to an embodiment is shown.

[0098] Figure 6 The method can be performed by a UE, a satellite, a gNB, or another network device. Additionally, the term "TAC" is shown in the figures and is an abbreviation for "TA command".

[0099] Referring to Figure 6 , at step 601, the UE determines whether to use a closed-loop method or an open-loop method. The determination can be made based on multiple factors explained above (e.g., the altitude of the satellite and the expected propagation delay).

[0100] If the closed-loop method is used, then at step 602, the UE uses the TA command. For example, the UE can receive the TA command based on msg2 / msgB.

[0101] At step 603, the UE sets the timer value for the TAC-valid timer. The TAC-valid timer can be set (or reset) each time a TA command is received.

[0102] At step 604, closed-loop TA is used. For example, the TA command can be received in msg2 / msgB or as the most recent TA command MAC CE.

[0103] At step 605, the UE determines whether the TA command is a TA command MAC CE. If the TA command is the most recent TA command MAC CE, the method returns to step 603. Otherwise, if the TA command is not a TA command MAC CE, then at step 606, the UE determines whether the TAC-valid timer has expired.

[0104] At step 606, if the TAC-valid timer has not expired, the method returns to step 604 and closed-loop TA is used. On the other hand, at step 606, if the TAC-valid timer has expired, then at step 607, the UE switches to using the open-loop TA method and can declare signal timing out-of-sync if the open-loop information is not available.

[0105] In step 608, the UE determines whether the TA command is a TA command MAC CE. If the TA command is a TA command MAC CE, the method returns to step 603. Otherwise, if the TA command is not a TA command MAC CE, the method returns to step 607.

[0106] Returning to reference step 601, if the open-loop method is used, in step 609 the UE uses open-loop TA. In step 610, the UE sets the OL-valid timer time value. As described above, the OL-valid timer can be set (or reset) based on open-loop information.

[0107] In step 611, the UE estimates the TA using the open-loop method.

[0108] In step 612, the UE determines whether open-loop information is available. If the open-loop information is available, the method returns to step 610. However, if the open-loop information is not available, in step 613 the UE determines whether the OL-valid timer has expired.

[0109] If the OL-valid timer has not expired in step 613, the method returns to step 611 and uses open-loop TA. On the other hand, if the OL-valid timer has expired, in step 614, the UE switches to using the closed-loop TA method, and if the TA command MAC CE is not available, signal timing out-of-sync can be declared.

[0110] In step 615, the UE determines whether open-loop information is available. If the open-loop information is available, the method returns to step 610. If the open-loop information is not available, the method returns to step 614.

[0111] According to another embodiment, the UE may not prioritize any TA (e.g., neither closed-loop nor open-loop is prioritized). This can be applied to the case of low RTD and can cover the case of high-altitude platform stations (HAPS) with large SCS. In this case, the UE will simply add the open-loop component and the closed-loop component as they are.

[0112] Accordingly, based on the TA description discussed above, the value of N can be updated based on the following procedures (1) and (2): TA :

[0113] For N TA Update / cumulate:

[0114] If closed-loop is prioritized;

[0115] If TAC is valid, update N based on the gNB command TA ;

[0116] Else do not update;

[0117] Else / / The open loop is prioritized;

[0118] If OL is valid, do not update;

[0119] Else update N based on the gNB command TA ;

[0120] End

[0121] … Program (1)

[0122] For N TA,UE-specific :

[0123] If the closed loop is prioritized;

[0124] If TAC - is valid, do not update;

[0125] Else update N TA,UE-specific : Based on open - loop calculation;

[0126] Else / / The open loop is prioritized;

[0127] If OL - is valid, update N TA,UE-specific : Based on open - loop calculation;

[0128] Else do not update;

[0129] End

[0130] … Program (2)

[0131] Correspondingly, the above description provides the configurations and conditions for defining whether the open loop or the closed loop should be prioritized, and also details the use and function of the timer for determining whether the open - loop component or the closed - loop component will be used.

[0132] For beam / BWP switching, four methods are provided to achieve improved beam / BWP switching: network - initiated configured beam / BWP switching; UE - initiated configured beam / BWP switching; conditional beam / BWP switching; and group beam / BWP switching.

[0133] Now the network - initiated configured beam / BWP switching method will be described.

[0134] In this embodiment, the network may configure the UE with a list of TCI states indices. This configuration may be done via RRC configuration or reconfiguration. The network may configure the UE via UE-specific configuration or configure a group of UEs together via group configuration. The list of TCI states indices may be calculated based on the UE's location, satellite movement direction, and beam / BWP planning. Knowledge of the satellite location and movement direction as well as beam / BWP planning may be provided to the network (e.g., via the UE or via a cloud storage system). The network may obtain the UE's location information by the UE periodically sending its location to the network. The network may also estimate the UE's location based on the UE's TA value.

[0135] For NTN, beam / BWP switching may be caused by the movement of the satellite, so the network may be able to predict the beam coverage areas that the UE will pass through in the near future.

[0136] Figure 7 A configuration in which 7 satellite beams are assigned to 3 BWPs according to an embodiment is shown.

[0137] Referring to Figure 7 , each beam transmitted from satellite 701 is assigned to a BWP. Beam #1 is assigned to BWP #2, beam #2 is assigned to BWP #2, beam #3 is assigned to BWP #3, beam #4 is assigned to BWP #2, beam #5 is assigned to BWP #3, beam #6 is assigned to BWP #2 and beam #7 is assigned to BWP #1. Beams #1 - #7 may be included in a single cell. Since the BWPs basically do not overlap, inter-beam interference can be reduced.

[0138] As Figure 7 shown, based on the movement of satellite 701, the network may predict that the route of UE 702 will pass through beam #2, beam #7, and beam #6. The network may indicate the list of TCI state indices respectively mapped to those beams. According to the network prediction, when UE 702 approaches the beam edge, the network or gNB will notify UE 702 to perform beam switching via RRC signaling, MAC CE, or DCI activation.

[0139] Additionally, at the time of beam switching, the network or gNB may cause the UE to switch BWPs by sending scheduling DCI to the UE with the new BWP index filled in the BWP indicator field in DCI format 0_1 or DCI format 1_1.

[0140] Since there is a mapping configuration between the beam and the BWP, the UE may be configured via the mapping information, and since the network may notify the UE to perform beam switching, the UE may also perform the corresponding BWP switching.

[0141] As the satellite moves, the UE can also move such that it deviates from the path initially predicted by the network.

[0142] Figure 8 A configuration is shown in which 7 satellite beams are allocated to 3 BWPs according to an embodiment.

[0143] Refer to Figure 8 , each beam transmitted from satellite 801 is allocated to a BWP. Beam #1 is allocated to BWP #2, beam #2 is allocated to BWP #2, beam #3 is allocated to BWP #3, beam #4 is allocated to BWP #2, beam #5 is allocated to BWP #3, beam #6 is allocated to BWP #2 and beam #7 is allocated to BWP #1. Beams #1 - #7 can be included in a single cell. Since the BWPs substantially do not overlap, inter - beam interference can be reduced.

[0144] As Figure 8 shown, since the network cannot accurately predict the movement of UE 802, it initially predicts that UE 802 will experience beam #2, beam #7 and beam #6. However, since both the UE and the satellite move, the UE will actually experience beam #2, beam #7 and beam #5. If the position of the UE is updated periodically, the network may be able to change the prediction and re - configure the UE with an updated list of TCI state indices.

[0145] Next, a beam / BWP switching method initiated by the UE (e.g., a beam / BWP switching method initiated by the UE) will now be described.

[0146] Figure 9 A configuration for broadcasting beam information to the network according to an embodiment is shown.

[0147] Refer to Figure 9 , beam information (such as beam width, beam center position, beam size and beam center elevation angle) can be broadcast by satellite 901 to the network in system information (such as the Master Information Block (MIB) or System Information Block (SIB)).

[0148] With such information, the UE can calculate the beam topology of the area around the UE. Optionally, as described above (e.g., refer to Figure 8 ), the network can configure a list of TCI state indices for the UE according to the beam / BWP plan. The UE can also have its own location information through GNSS capability information or through network positioning services. Using all this information, the UE can fully know when to perform beam / BWP switching and which beam / BWP to switch to. Accordingly, once the UE approaches the beam edge, it can switch to an adjacent beam.

[0149] Now, a conditional beam / BWP switching method will be described.

[0150] In a manner similar to the execution of conditional switching, beam / BWP switching can be conditional. In addition to the above list of TCI state indices, the UE can also be provided with conditions regarding when beam / BWP switching should be initiated. The condition can be based on an RS received power (RSRP) threshold, an RS strength indicator (RSSI) threshold, and a quality threshold. The condition can be preconfigured for the UE / cell, or can be signaled via dedicated and / or common RRC signaling. The condition can be linked to a TCI state, where each TCI state includes a condition.

[0151] For example, when the UE is in TCI state k, the UE can monitor the parameter associated with the condition in TCI state k. When the condition is met, the UE can initiate a beam / BWP switch to another TCI state j in the list of TCI indices provided to the UE. In addition, the conditional beam / BWP switching method can be applied to UE-initiated or network-initiated beam / BWP switching.

[0152] Next, a group beam / BWP switching method (e.g., sending a group command to multiple UEs) will be described.

[0153] Figure 10 A flowchart of a group beam / BWP switching method according to an embodiment is shown.

[0154] According to one method, in step 1001, multiple UEs are grouped. The multiple UEs can be grouped in a variety of different ways. For example, the grouping can be done by a higher layer. For example, UEs in a plane can be assigned to the same group. The network can assign a GROUP_RNTI to each group.

[0155] Additionally or alternatively, the grouping can be done based on the geographical location. For example, a geographical area can be divided into multiple regions. Each region can be a predetermined shape (such as a rectangle). UEs within a region are part of the same group. Each region can be uniquely assigned a GROUP_RNTI by the network. When a UE moves from one region to another region, it can switch from one group to another group and use the GROUP_RNTI associated with the new region. The partitioning information can be indicated by RRC signaling or other higher layer signaling.

[0156] An example of geographical location grouping is as follows. The UE requests zoning information for the geographical area to which the UE belongs and sends its location information (sending the location information can be done roughly or embedded to mitigate privacy issues). Then, the network sends the UE zoning information for the area around / near the UE's location. The zoning information may include a list of areas near the UE. Each area may include a geographical description of the area (e.g., coordinates of a corner) and an associated GROUP_RNTI. When the location of the UE has moved significantly since it obtained the zoning information, it may request updated zoning information.

[0157] After being grouped, at step 1002, the UE monitors the common search space. The UE may monitor the common search space for group DCI (DCI format 2_X) to indicate beam / BWP switching. The DCI may include one bit for indicating the switch and the TCI state index to be used from now on, and may be scrambled by the GROUP_RNTI. Additionally or alternatively, the DCI may include a group list and the TCI state index. Each group in the DCI may switch to the corresponding TCI state index.

[0158] At step 1003, beam / BWP switching is performed when beam / BWP switching is indicated in the common search space.

[0159] Group switching can also be done in conjunction with conditional switching. For zoning, each area may additionally include and depend on conditions. When the conditions are met, the UE may switch by itself. Additionally, the UE may receive a DCI group command, but only perform the switch when the conditions are met. Thus, in practice, even nearby UEs may have different radio conditions due to various conditions such as blockages. Having conditional switching can give each UE a bit of leeway and ensure that the switch is made at the most appropriate time.

[0160] Figure 11 An electronic device in a network environment according to an embodiment is shown.

[0161] Referring to Figure 11, an electronic device 1101 (e.g., a mobile terminal including a GPS function) in a network environment 1100 may communicate with an electronic device 1102 via a first network 1198 (e.g., a short-range wireless communication network), or communicate with an electronic device 1104 or a server 1108 via a second network 1199 (e.g., a long-range wireless communication network). The electronic device 1101 may communicate with the electronic device 1104 via the server 1108. The electronic device 1101 may include a processor 1120, a memory 1130, an input device 1150, a sound output device 1155, a display device 1160, an audio module 1170, a sensor module 1176, an interface 1177, a haptic module 1179, a camera module 1180, a power management module 1188, a battery 1189, a communication module 1190, a subscriber identification module (SIM) 1196, or an antenna module 1197 including a GNSS antenna. In one embodiment, at least one of the components (e.g., the display device 1160 or the camera module 1180) may be omitted from the electronic device 1101, or one or more other components may be added to the electronic device 1101. In one embodiment, some of the components may be implemented as a single integrated circuit (IC). For example, the sensor module 1176 (e.g., a fingerprint sensor, an iris sensor, or an illuminance sensor) may be embedded in the display device 1160 (e.g., a display).

[0162] The processor 1120 may run software (e.g., a program 1140) to control at least one other component (e.g., a hardware component or a software component) connected to the processor 1120 of the electronic device 1101, and may perform various data processing or calculations. As at least part of the data processing or calculation, the processor 1120 may load a command or data received from another component (e.g., the sensor module 1176 or the communication module 1190) into the volatile memory 1132, process the command or data stored in the volatile memory 1132, and store the resulting data in the non-volatile memory 1134. The processor 1120 may include a main processor 1121 (e.g., a central processing unit (CPU) or an application processor) and an auxiliary processor 1123 (e.g., a graphics processing unit (GPU), an image signal processor (ISP), a sensor hub processor, or a communication processor) that is operationally independent of or combined with the main processor 1121. Additionally or alternatively, the auxiliary processor 1123 may be adapted to consume less power than the main processor 1121, or perform a specific function. The auxiliary processor 1123 may be implemented separately from the main processor 1121, or as part of the main processor 1121.

[0163] When the main processor 1121 is in an inactive (e.g., sleep) state, the auxiliary processor 1123 (instead of the main processor 1121) may control at least some of the functions or states related to at least one of the components of the electronic device 1101 (e.g., the display device 1160, the sensor module 1176, or the communication module 1190), or when the main processor 1121 is in an active state (e.g., running an application), the auxiliary processor 1123 may control at least some of the functions or states related to at least one of the components of the electronic device 1101 (e.g., the display device 1160, the sensor module 1176, or the communication module 1190) together with the main processor 1121. According to one embodiment, the auxiliary processor 1123 (e.g., an ISP or a communication processor) may be implemented as part of another component (e.g., the camera module 1180 or the communication module 1190) that is functionally related to the auxiliary processor 1123.

[0164] The memory 1130 may store various data used by at least one component of the electronic device 1101 (e.g., the processor 1120 or the sensor module 1176). The various data may include, for example, software (e.g., the program 1140) and input data or output data for commands related thereto. The memory 1130 may include a volatile memory 1132 or a non-volatile memory 1134.

[0165] The program 1140 may be stored as software in the memory 1130, and the program 1140 may include, for example, an operating system (OS) 1142, middleware 1144, or an application 1146.

[0166] The input device 1150 may receive commands or data from the outside of the electronic device 1101 (e.g., a user) to be used by other components of the electronic device 1101 (e.g., the processor 1120). The input device 1150 may include, for example, a microphone, a mouse, or a keyboard.

[0167] The sound output device 1155 may output a sound signal to the outside of the electronic device 1101. The sound output device 1155 may include, for example, a speaker or a receiver. The speaker may be used for general purposes such as playing multimedia or recording, and the receiver may be used for receiving incoming calls. According to one embodiment, the receiver may be implemented separately from the speaker or as part of the speaker.

[0168] The display device 1160 may visually provide information to the outside (e.g., a user) of the electronic device 1101. The display device 1160 may include, for example, a display, a holographic device, or a projector, and a control circuit for controlling a corresponding one of the display, the holographic device, and the projector. According to one embodiment, the display device 1160 may include a touch circuit adapted to detect a touch or a sensor circuit (e.g., a pressure sensor) adapted to measure the intensity of a force caused by the touch.

[0169] The audio module 1170 may convert sound into an electrical signal and vice versa. According to one embodiment, the audio module 1170 may obtain sound via the input device 1150, or output sound via the sound output device 1155 or headphones of an external electronic device 1102 directly (e.g., wiredly) or wirelessly connected to the electronic device 1101.

[0170] The sensor module 1176 may detect an operating state of the electronic device 1101 (e.g., power or temperature) or an environmental state outside the electronic device 1101 (e.g., a state of a user), and then generate an electrical signal or a data value corresponding to the detected state. The sensor module 1176 may include, for example, a gesture sensor, a gyro sensor, an atmospheric pressure sensor, a magnetic sensor, an acceleration sensor, a grip sensor, a proximity sensor, a color sensor, an infrared (IR) sensor, a biometric sensor, a temperature sensor, a humidity sensor, or an illuminance sensor.

[0171] The interface 1177 may support one or more specific protocols used to directly (e.g., wiredly) or wirelessly connect the electronic device 1101 to an external electronic device 1102. According to one embodiment, the interface 1177 may include, for example, a high definition multimedia interface (HDMI), a universal serial bus (USB) interface, a secure digital (SD) card interface, or an audio interface.

[0172] The connection end 1178 may include a connector through which the electronic device 1101 may be physically connected to an external electronic device 1102. According to one embodiment, the connection end 1178 may include, for example, an HDMI connector, a USB connector, an SD card connector, or an audio connector (e.g., a headphone connector).

[0173] The haptic module 1179 may convert an electrical signal into a mechanical stimulus (e.g., vibration or motion) or an electrical stimulus that can be recognized by a user via his tactile or kinesthetic sense. According to one embodiment, the haptic module 1179 may include, for example, a motor, a piezoelectric element, or an electrical stimulator.

[0174] The camera module 1180 may capture a still image or a moving image. According to one embodiment, the camera module 1180 may include one or more lenses, an image sensor, an ISP, or a flash.

[0175] The power management module 1188 may manage the power supply to the electronic device 1101. The power management module 1188 may be implemented as at least part of, for example, a power management IC (PMIC).

[0176] The battery 1189 may supply power to at least one component of the electronic device 1101. According to one embodiment, the battery 1189 may include, for example, a non-rechargeable primary battery, a rechargeable secondary battery, or a fuel cell.

[0177] The communication module 1190 may support establishing a direct (e.g., wired) communication channel or a wireless communication channel between the electronic device 1101 and an external electronic device (e.g., the electronic device 1102, the electronic device 1104, or the server 1108), and perform communication via the established communication channel. The communication module 1190 may include one or more communication processors capable of operating independently of the processor 1120 (e.g., an application processor), and support direct (e.g., wired) communication or wireless communication. According to one embodiment, the communication module 1190 may include a wireless communication module 1192 (e.g., a cellular communication module, a short-range wireless communication module, or a GNSS communication module) or a wired communication module 1194 (e.g., a local area network (LAN) communication module or a power line communication (PLC) module). The respective one of these communication modules may communicate with the external electronic device via a first network 1198 (e.g., a short-range communication network, such as Bluetooth, Wi-Fi Direct, or the Infrared Data Association (IrDA) standard) or a second network 1199 (e.g., a long-range communication network, such as a cellular network, the Internet, or a computer network (e.g., a LAN or a wide area network (WAN))). These various types of communication modules may be implemented as a single component (e.g., a single IC), or these various types of communication modules may be implemented as multiple separate components (e.g., multiple ICs). The wireless communication module 1192 may identify and authenticate the electronic device 1101 in a communication network (such as the first network 1198 or the second network 1199) using user information (e.g., an International Mobile Subscriber Identity (IMSI)) stored in the SIM 1196.

[0178] The antenna module 1197 may transmit signals or power to the outside of the electronic device 1101 (e.g., an external electronic device) or receive signals or power from the outside of the electronic device 1101 (e.g., an external electronic device). According to one embodiment, the antenna module 1197 may include one or more antennas, and thus, at least one antenna suitable for a communication scheme to be used in a communication network (such as the first network 1198 or the second network 1199) may be selected by, for example, the communication module 1190 (e.g., the wireless communication module 1192). Subsequently, signals or power may be transmitted or received between the communication module 1190 and the external electronic device via the selected at least one antenna.

[0179] At least some of the above components may be interconnected via an inter-peripheral communication scheme (e.g., a bus, general-purpose input / output (GPIO), serial peripheral interface (SPI), or mobile industry processor interface (MIPI)) and communicatively transmit signals (e.g., commands or data) therebetween.

[0180] According to one embodiment, commands or data may be transmitted or received between the electronic device 1101 and the external electronic device 1104 via a server 1108 connected to the second network 1199. Each of the electronic devices 1102 and 1104 may be a device of the same type as the electronic device 1101 or a device of a different type from the electronic device 1101. All or some of the operations to be run on the electronic device 1101 may be run on one or more of the external electronic devices 1102, external electronic device 1104, or server 1108. For example, if the electronic device 1101 is to automatically execute a function or service or is to execute a function or service in response to a request from a user or another device, the electronic device 1101 may request at least part of the function or service to be executed by the one or more external electronic devices instead of running the function or service, or in addition to running the function or service, the electronic device 1101 may also request at least part of the function or service to be executed by the one or more external electronic devices. The one or more external electronic devices that receive the request may execute the requested at least part of the function or service or execute an additional function or additional service related to the request and transmit the result of the execution to the electronic device 1101. The electronic device 1101 may provide the result as at least part of a reply to the request with or without further processing of the result. For this purpose, for example, cloud computing technology, distributed computing technology, or client-server computing technology may be used.

[0181] One embodiment may be implemented as software (e.g., program 1140) including one or more instructions readable by a machine (e.g., electronic device 1101) and stored in a storage medium (e.g., internal memory 1136 or external memory 1138). For example, under the control of a processor, the processor of the electronic device 1101 may invoke at least one of the one or more instructions stored in the storage medium and run the at least one instruction with or without using one or more other components. Thus, the machine can be operated to perform at least one function according to the at least one instruction invoked. The one or more instructions may include code generated by a compiler or code executable by an interpreter. The machine-readable storage medium may be provided in the form of a non-transitory storage medium. The term "non-transitory" indicates that the storage medium is a tangible device and does not include signals (e.g., electromagnetic waves), but this term does not distinguish between data being stored semi-permanently in the storage medium and data being stored temporarily in the storage medium.

[0182] According to one embodiment, the method of the present disclosure may be included and provided in a computer program product. The computer program product may be traded between a seller and a purchaser as a product. The computer program product may be distributed in the form of a machine-readable storage medium (e.g., compact disc read-only memory (CD-ROM)), or the computer program product may be distributed online (e.g., downloaded or uploaded) via an application store (e.g., PlayStore TM ) or directly between two user devices (e.g., smart phones) (e.g., downloaded or uploaded). If it is distributed online, at least part of the computer program product may be generated temporarily, or at least part of the computer program product may be stored at least temporarily in a machine-readable storage medium (such as the memory of a manufacturer's server, an application store's server, or a forwarding server).

[0183] According to one embodiment, each of the above components (e.g., a module or a program) may include a single entity or multiple entities. One or more of the above components may be omitted, or one or more other components may be added. Optionally or additionally, multiple components (e.g., modules or programs) may be integrated into a single component. In this case, the integrated component may still perform the one or more functions of each of the multiple components in the same or similar manner as the corresponding one of the multiple components performed the one or more functions before integration. The operations performed by a module, a program, or another component may be performed sequentially, in parallel, repeatedly, or in a heuristic manner, or one or more of the operations may be run in a different order or omitted, or one or more other operations may be added.

[0184] Accordingly, as described above, the present disclosure describes various embodiments capable of implementing new open-loop TA and closed-loop TA calculation methods, wherein the method enables signals to be sent to / from a UE via LEO, MEO, and GEO satellites with accurate TA commands, thereby avoiding timing issues (e.g., double correction) typically associated with signal transmission over NTN. Additionally, the present disclosure provides solutions for predicting satellite movement to assist in faster beam switching with improved efficiency and reduced signaling.

[0185] Although specific embodiments of the present disclosure have been described in the specific implementation manners of the present disclosure, the present disclosure may be modified in various forms without departing from the scope of the present disclosure. Therefore, the scope of the present disclosure should not be determined based only on the described embodiments, but rather based on the appended claims and their equivalents.

Claims

1. A method for performing timing advance adjustment between a user equipment (UE) and a non-terrestrial network (NTN), the method comprising: Receive and decode a Media Access Control (MAC) Control Element (CE) including closed-loop information; Receive and decode system information including open-loop information; Determine a timing advance value based on the closed-loop information or the open-loop information; And Control the timing of an uplink transmission signal transmitted from a UE based on the timing advance value, wherein the step of determining the timing advance value includes: Configure a priority timer, Assign a priority to a closed-loop method or an open-loop method, When the priority is assigned to the closed-loop method, determine the timing advance value based on the closed-loop information, and if the priority timer has expired, revert to the open-loop method, When the priority is assigned to the open-loop method, determine the timing advance value based on the open-loop information, and if the priority timer has expired, revert to the closed-loop method.

2. The method according to claim 1, wherein, The closed-loop information includes a timing advance command, and wherein the open-loop information includes satellite ephemeris data and a common timing advance.

3. The method according to claim 2, wherein, The step of determining the timing advance value includes: Determine a closed-loop timing advance component based on the timing advance command; and Determine an open-loop timing advance component, and wherein the step of determining the open-loop timing advance component includes: Calculate a UE-specific timing advance based on the location of the UE and the satellite ephemeris data; and Determine the open-loop timing advance component based on the UE-specific timing advance and the common timing advance.

4. The method according to claim 1, further comprising: When the priority is assigned to the closed-loop method, restart the priority timer when a timing advance command is received.

5. The method according to claim 1, further comprising: When the priority is assigned to the open-loop method, restart the priority timer when the satellite ephemeris data and the common timing advance are available.

6. The method according to claim 1, further comprising: When the priority is assigned to the open-loop method, if the location of the UE cannot be determined, revert to the closed-loop method.

7. The method according to claim 1, wherein, The step of assigning the priority includes: assigning the priority to a plurality of UEs located within a cell.

8. The method according to claim 1, wherein, The step of determining the timing advance value based on the closed-loop information or the open-loop information includes: Determine a first timing advance value based on the closed-loop information at a first time; and Determine a second timing advance value based on the open-loop information at a second time, and wherein the step of controlling the timing of the uplink transmission signal further includes: Control the timing of the uplink transmission signal based on the first timing advance value at the first time, and Control the timing of the uplink transmission signal based on the second timing advance value at the second time.

9. A user equipment (UE), comprising: A memory; And A processor configured to: Receive and decode a Media Access Control (MAC) Control Element (CE) including closed-loop information, Receive and decode system information including open-loop information, Determine a timing advance value based on the closed-loop information or the open-loop information, and Control the timing of an uplink transmission signal transmitted from a UE based on the timing advance value, wherein the processor is further configured to: Configure a priority timer, Assign a priority to a closed-loop method or an open-loop method, and When the priority is assigned to the closed-loop method, determine the timing advance value based on the closed-loop information, and if the priority timer has expired, revert to the open-loop method, When the priority is assigned to the open-loop method, determine the timing advance value based on the open-loop information, and if the priority timer has expired, revert to the closed-loop method.

10. The UE according to claim 9, wherein, The closed-loop information includes a timing advance command, and wherein, the open-loop information includes satellite ephemeris data and common timing advance.

11. The UE according to claim 10, wherein, The processor is further configured to: determine a closed-loop timing advance component based on the timing advance command, and determine an open-loop timing advance component by the following steps: calculate a UE-specific timing advance based on the position of the UE and the satellite ephemeris data; and determine the open-loop timing advance component based on the UE-specific timing advance and the common timing advance.

12. The UE according to claim 9, wherein, The processor is further configured to: when a priority is assigned to the closed-loop method, restart the priority timer when a timing advance command is received.

13. The UE according to claim 9, wherein, The processor is further configured to: when a priority is assigned to the open-loop method, restart the priority timer when the satellite ephemeris data and the common timing advance are available.

14. The UE according to claim 9, wherein, The processor is further configured to: when a priority is assigned to the open-loop method, if the position of the UE cannot be determined, revert to the closed-loop method.

15. The UE according to claim 9, wherein, The processor is further configured to: assign priorities to multiple UEs located within the cell.

16. The UE according to claim 9, wherein, The processor is further configured to: determine a first timing advance value based on the closed-loop information at a first time, determine a second timing advance value based on the open-loop information at a second time, control the timing of the uplink transmission signal based on the first timing advance value at the first time, and control the timing of the uplink transmission signal based on the second timing advance value at the second time.

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