Systems and methods for global navigation satellite system-free operation modes for non-terrestrial networks

Abstract

Systems and methods for a global navigation satellite system (GNSS)-free operation mode for a non-terrestrial network (NTN) are disclosed. User equipment (UE) of the NTN identifies that GNSS data acquisition fails; transmitting, to a base station, a request to transition from operating in a first timing advance (TA) mode in which the UE determines a first TA value using the GNSS data to operating in a second TA mode in which the UE determines a second TA value without using any GNSS data; receiving a reply from the base station indicating that the UE is capable of transitioning to operate in the second TA mode; performing the transition; determining a timing of an uplink (UL) transmission using the correspondingly calculated second TA value; and transmitting the UL transmission according to the timing. Similar base station behavior is discussed. In some cases, the UE determines to make a transition based on a factor other than GNSS (e.g., power saving).

Description

Technical Field

[0001] The present application generally relates to wireless communication systems, including wireless communication systems that use non-terrestrial networks (NTN) for communication. Background Art

[0002] Wireless mobile communication technologies use various standards and protocols to send data between base stations and wireless communication devices. For example, wireless communication system standards and protocols can include, for example, the 3rd Generation Partnership Project (3GPP) Long Term Evolution (LTE) (e.g., 4G), 3GPP New Radio (NR) (e.g., 5G), and the Institute of Electrical and Electronics Engineers (IEEE) 802.11 standard for wireless local area networks (WLAN) (commonly referred to within the industry as ).

[0003] As envisioned by 3GPP, different wireless communication system standards and protocols can use various radio access networks (RANs) for communication between the base stations of the RAN (sometimes also referred to as RAN nodes, network nodes, or simply nodes) and wireless communication devices known as user equipment (UE). 3GPP RAN can include, for example, Global System for Mobile Communications (GSM), Enhanced Data Rate for GSM Evolution (EDGE) RAN (GERAN), Universal Terrestrial Radio Access Network (UTRAN), Evolved Universal Terrestrial Radio Access Network (E-UTRAN), and / or Next Generation Radio Access Network (NG-RAN).

[0004] Each RAN can use one or more radio access technologies (RATs) for communication between the base station and the UE. For example, GERAN implements GSM and / or EDGE RAT, UTRAN implements Universal Mobile Telecommunications System (UMTS) RAT or other 3GPP RAT, E-UTRAN implements LTE RAT (sometimes simply referred to as LTE), and NG-RAN implements NR RAT (which NR RAT is sometimes referred to herein as 5G RAT, 5G NR RAT, or simply NR). In some deployments, E-UTRAN can also implement NR RAT. In some deployments, NG-RAN can also implement LTE RAT.

[0005] The base stations used by the RAN can correspond to that RAN. An example of an E-UTRAN base station is an Evolved Universal Terrestrial Radio Access Network (E-UTRAN) Node B (commonly also denoted as Evolved Node B, Enhanced Node B, eNodeB, or eNB). An example of an NG-RAN base station is a Next Generation Node B (sometimes also referred to as gNodeB or gNB).

[0006] The RAN provides communication services with external entities through its connection to the core network (CN). For example, E-UTRAN can utilize the evolved packet core (EPC), while NG-RAN can utilize the 5G core network (5GC). Description of the Drawings

[0007] To facilitate the identification of the discussion of any particular element or action, one or more of the most significant digits in the reference numerals refer to the drawing number in which the element was first introduced.

[0008] Figure 1 Illustrates the NTN architecture of a wireless communication system according to an embodiment.

[0009] Figure 2 Illustrates the NTN architecture of a wireless communication system according to an embodiment.

[0010] Figure 3 Illustrates a timeline corresponding to the use of the GNSS-free operation mode of a UE according to the embodiments discussed herein, where the UE communicates with a base station through a service link of an NTN network.

[0011] Figure 4 Illustrates a procedure performed by a UE for entering and exiting a closed-loop TA mode according to the embodiments of the present disclosure.

[0012] Figure 5 Illustrates a method of a UE of an NTN according to the embodiments discussed herein.

[0013] Figure 6 Illustrates a method of a base station of an NTN according to the embodiments discussed herein.

[0014] Figure 7 Illustrates a method of a UE of an NTN according to the embodiments discussed herein.

[0015] Figure 8 Illustrates an example architecture of a wireless communication system according to the embodiments disclosed herein.

[0016] Figure 9 Illustrates a system for performing signaling between a wireless device and a RAN device connected to a core network of a CN device according to the embodiments disclosed herein. Detailed Description

[0017] The various embodiments are described with respect to a UE. However, the indexing of the UE is provided merely for illustrative purposes. Example embodiments can be used with any electronic component that can establish a connection to a network and is configured with hardware, software, and / or firmware for exchanging information and data with the network. Thus, the UE as described herein is used to represent any suitable electronic component.

[0018] Embodiments of Non-Terrestrial Networks (NTN)

[0019] Figure 1 Illustrates the NTN architecture 100 of a wireless communication system according to an embodiment. The NTN architecture 100 includes a core network (CN) 102, a terrestrial base station 104, a satellite gateway 106, a satellite 108, and a UE 110. The terrestrial base station 104, the satellite gateway 106, and the satellite 108 may be included in the RAN 112.

[0020] In some embodiments, the RAN 112 includes an E-UTRAN, the CN 102 includes an EPC, and the terrestrial base station 104 includes an eNB. In these cases, the CN link 114 connecting the CN 102 and the terrestrial base station 104 may include an S1 interface.

[0021] In some embodiments, the RAN 112 includes an NG-RAN, the CN 102 includes a 5GC, and the terrestrial base station 104 includes a gNB or a next-generation eNB (ng-eNB). In such cases, the CN link 114 connecting the CN 102 and the terrestrial base station 104 may include an NG interface.

[0022] The NTN architecture 100 illustrates an architecture based on a "bent pipe" or "transparent" satellite. In such a bent pipe system, the terrestrial base station 104 communicates with the satellite 108 via the satellite gateway 106 over a feeder link 116. The satellite 108 may be equipped with one or more antennas capable of broadcasting a cell according to the RAN 112, and the UE 110 may be equipped with one or more antennas capable of communicating with the satellite 108 via the Uu interface over the cell (e.g., a mobile parabolic antenna, an omnidirectional phased array antenna, etc.) (such communication can be said to use the illustrated service link 118). Then, the payload provided on the satellite 108 transparently forwards data between the satellite gateway 106 and the UE 110 using the feeder link 116 between the satellite gateway 106 and the satellite 108 and the service link 118 between the satellite 108 and the UE 110. The payload may perform radio frequency (RF) conversion and / or amplification in both the uplink (UL) and the downlink (DL) to enable such communication.

[0023] In Figure 1 the illustrated embodiment, the terrestrial base station 104 is illustrated as not having the ability to directly perform terrestrial wireless communication with the UE. However, it is envisioned that in other embodiments, such terrestrial base stations that communicate with the satellite 108 using the satellite gateway 106 may (also) have this function (i.e., as in Figure 8 the terrestrial base stations 812 and 814, which will be described below).

[0024] It should be understood that inFigure 1 In an alternative embodiment, satellite 108 may instead be a non-satellite NTN vehicle (e.g., an airplane, an unmanned aerial vehicle (UAV), an unmanned aerial vehicle system (UAS), a dirigible, a balloon, etc.). Further, it should be understood that in such alternative embodiments, satellite gateway 106 may instead be a gateway for or corresponding to the applicable type of NTN vehicle.

[0025] Figure 2 Illustrated is an NTN architecture 200 of a wireless communication system according to an embodiment. NTN architecture 200 includes a CN 202, a satellite gateway 204, a satellite base station 206, and a UE 208. Satellite gateway 204 and satellite base station 206 may be included in a RAN 210.

[0026] In some embodiments, RAN 210 includes an E-UTRAN, and CN 202 includes an EPC. In these cases, the CN link 212 connecting CN 202 and satellite gateway 204 may include an S1 interface.

[0027] In some embodiments, RAN 210 includes an NG-RAN, and CN 202 includes a 5GC. In such cases, the CN link 212 connecting CN 202 and satellite gateway 204 may include an NG interface.

[0028] NTN architecture 100 implements a "regenerative" satellite-based architecture. In such a regenerative system, the functions of the base station are provided on satellite base station 206, and the communication between these base station functions and CN 202 is forwarded through the interfaces found on CN link 212 (e.g., S1 interface and / or NG interface), via satellite gateway 204 and feeder link 214 to satellite base station 206. Satellite base station 206 may be equipped with one or more antennas capable of broadcasting a cell according to RAN 210, and UE 208 may be equipped with one or more antennas capable of communicating with satellite base station 206 via the Uu interface on the cell (e.g., a mobile parabolic antenna, an omnidirectional phased array antenna, etc.) (such communication can be said to use the illustrated service link 216). Then, the payload provided on satellite base station 206 forwards data between satellite gateway 204 and UE 208 using feeder link 214 between satellite gateway 204 and satellite base station 206 and service link 216 between satellite base station 206 and UE 208. The payload may perform RF conversion and / or amplification in both the uplink (UL) and the downlink (DL) to enable this communication, as well as to implement the functions of the base station (e.g., as an eNB, ng-eNB, or gNB, as corresponding to the type of RAN 210) as if these were provided on satellite base station 206.

[0029] In an implementation of an NTN architecture of an NG-RAN that also uses integrated access and backhaul (IAB), it is possible that a gNB control unit function (CU) can be located on the ground and communicate with a satellite carrying the corresponding gNB donor unit function (DU) using a satellite gateway, where the F1 interface between the CU and the DU is supported by a feeder link 214. In such cases, the CU and the DU can each be understood as part of the NG-RAN.

[0030] It should be understood that in Figure 2 an alternative implementation, the satellite base station 206 can instead be a non-satellite NTN base station (e.g., an aircraft, UAV, UAS, airship, balloon, etc.). Further, it should be understood that in such an alternative implementation, the satellite gateway 204 can instead be a gateway for or corresponding to the applicable NTN vehicle type. Thus, for the disclosure herein, implementations involving a "satellite" should be understood as examples within this larger context (e.g., it should be understood that similar implementations using non-satellite NTN vehicles can also be developed based on the principles discussed in those implementations).

[0031] Embodiments of Uplink (UL) Time and Frequency Synchronization

[0032] In some wireless communication systems, the timing advance (TA) values applied by an NR NTN UE in various radio resource control (RRC) states (e.g., RRC_IDLE, RRC_INACTIVE, and RRC_CONNECTED) are given by the following formula:

[0033] T TA =(N TA +N TA,UE特定的 +N TA，公共 +N TA，偏移 )×T C , where:

[0034] T TA is the TA value;

[0035] N TA is 0 for a physical random access channel (PRACH) procedure and starts to be updated from the TA command field in the PRACH-based message 2 (Msg2) and / or message B (MsgB) and / or medium access control (MAC) control element (MAC-CE) TA command (note that the specific details of the update and / or accumulation for N TA can follow various possibilities);

[0036] N TA,UE特定的 is the UE self-estimated value for pre-compensating the service link delay for the TA;

[0037] NTA，公共 is the network control common value for TA and may include any timing offset that the network deems appropriate (note that N with a value of 0 may be supported TA，公共 , and various cases for specific signaling details (e.g., including granularity) may be considered);

[0038] N TA，偏移 is a fixed offset; and

[0039] T C is the basic time unit of the RAT.

[0040] It can be noted that the applicable N TA may vary between different embodiments. In some embodiments, the UE may not assume that the round-trip time (RTT) between the UE and the base station is equal to the TA calculated for Message 1 (Msg1) and / or Message A (MsgA) for the PRACH. Further, in some embodiments, N TA，公共 is understood as a common timing offset.

[0041] It can be envisioned that the NTN UE may have global navigation satellite system (GNSS) capabilities (meaning it has the ability to receive GNSS signaling and use the GNSS signaling to determine the location of the UE). In some wireless communication systems, the NTN UE in the RRC_IDLE state or the RRC_INACTIVE state may be configured to support the generation and use of UE-specific TA calculations that are at least partially based on the GNSS-acquired location of the NTN UE (and other relevant information, such as, for example, the serving satellite ephemeris). For such cases, the NR NTN UE in the RRC_IDLE state or the RRC_INACTIVE state may use its acquired GNSS location and satellite ephemeris information to calculate frequency pre-compensation to offset the shift / account for the Doppler effect experienced on the serving link between the UE and the satellite.

[0042] The NR NTN UE in the RRC_CONNECTED state may also use its acquired GNSS location and satellite ephemeris to perform frequency pre-compensation to offset the shift / account for the Doppler experienced on the serving link. Additionally, the NTN UE in the RRC_CONNECTED state may be configured to support UE-specific TA calculations based at least on its GNSS-acquired location and the serving satellite ephemeris.

[0043] In some embodiments of sporadic short transmission cases, if / when the GNSS location information at the UE becomes outdated, the NTN UE in the RRC_CONNECTED state may return to the idle mode and re-acquire GNSS location lock.

[0044] The NTN UE can autonomously determine its GNSS validity duration (e.g., in X seconds and / or minutes), and report information associated with this validity duration to the network via RRC signaling. In various cases, X can be 10 seconds, 20 seconds, 30 seconds, 40 seconds, 50 seconds, 60 seconds, 5 minutes, 10 minutes, 15 minutes, 20 minutes, 25 minutes, 30 minutes, 60 minutes, 90 minutes, 120 minutes, and / or infinity.

[0045] Embodiments of GNSS Operation

[0046] For various wireless communication systems (e.g., NR NTN), specific implementations of enhanced GNSS operations have been considered. Such enhanced GNSS operations can involve RRC_CONNECTED state operation robustness for the case of NTN UEs with GNSS capabilities and corresponding to the case of GNSS interruption at the NTN UE. Such GNSS interruptions may occur at the NTN UE due to, for example, the UE location (e.g., the UE is in a location where it cannot receive GNSS signaling). Such GNSS interruptions can be understood to occur during the duration when the NTN UE does not receive GNSS signaling. Note that in different implementation scenarios, the time length of the GNSS interruption period using the enhanced GNSS operations described herein can vary.

[0047] Note that for the sake of discussion, "NTN UE" may be more simply referred to as UE in this document.

[0048] Furthermore, in this document, "closed-loop TA mode" may refer to the case where the UE uses the information received from the base station to determine the TA value, and the case where the UE does not use the GNSS information determined at the UE to calculate the TA.

[0049] Even further, "open-loop and closed-loop TA mode" may refer to the case where the UE can use the GNSS information determined at the UE (independent of the RAN / base station) in combination with "closed-loop" type information to calculate the TA value. Therefore, it should be understood that the GNSS information determined at the UE is an example of "open-loop" type information.

[0050] In the context of the current wireless communication system using NTN UEs that can use GNSS operations depending on such open-loop GNSS information, there may be no additional mechanism to support (fully) the closed-loop TA mode (e.g., for the case when the expected GNSS information is not available at / for the UE). For the subsequent disclosure, note that "closed-loop mode" refers to the case where the open-loop component of GNSS information is not used and thus the "open-loop and closed-loop TA mode" is not used.

[0051] Each of the open TA mode and the closed / open TA mode can be an example of the "TA mode" as discussed herein.

[0052] The embodiments disclosed herein discuss systems, methods, and implementations for the closed-loop TA mode. Such contexts may utilize enhanced TA commands including one or more aspects, such as: an extended TA range, a TA drift rate, and / or a higher-order derivative of the TA drift rate. Further, in some cases, the closed-loop TA mode may include a frequency offset command.

[0053] The embodiments disclosed herein also discuss procedures / mechanisms for enabling an NTN UE to enter and / or exit the closed-loop TA mode. For example, such procedures / mechanisms may include using closed-loop TA mode trigger conditions and corresponding signaling defined according to various details, including signaling content and signaling containers.

[0054] Embodiments of GNSS-Free Operation Mode for NTN

[0055] In some embodiments, a closed-loop TA mode used in the NTN context may be introduced. In this state, closed-loop information is used to adjust the uplink transmission TA, and no open-loop TA information based on GNSS and / or ephemeris affects the calculation.

[0056] Consider the TA value T TA The generalized formula:

[0057] T TA =(N TA +N TA,UE特定的 +N TA，公共 +N TA，偏移 )×T C .

[0058] In the case of the closed-loop TA control mode, it is possible that N TA,UE特定的 , i.e., the UE self-estimated value used for pre-compensating the serving link delay (e.g., which may be at least partially based on GNSS information), can be considered as the "open-loop component" of T TA (the finally calculated TA value used at the UE), and thus is not used in the TA calculation formula in the closed-loop TA mode (i.e., set to 0). Further, whether to use N TA，公共 in the TA calculation formula in the closed-loop TA mode can be optional.

[0059] When considering the TA calculation formula in the closed-loop TA mode (e.g., where GNSS information is unavailable / used by the UE), the control of T TA may depend on the calculation of N TA (which is the finally network-controlled value), so as to provide enhanced TA control for this context. Note that NTA can be considered as T TA 's "closed-loop component" (the finally calculated TA at the UE).

[0060] In a first implementation for calculating N TA in the closed-loop TA mode, the MAC-CE can be transmitted from the network / base station to the UE. This MAC-CE can provide the UE with a TA drift rate (D TA-漂移 ) that can be used by the UE. In some cases, the MAC-CE can additionally include the second derivative of the TA drift (D TA-driftvariant ) and / or higher-order derivatives. The epoch time (t 历元 ) of the MAC-CE TA command can also be provided in the MAC-CE.

[0061] Then, T TA is calculated by using the new N TA，新 value (N TA ) in the TA calculation formula, where:

[0062] N TA，新 (t) = N TA，旧 + D TA-漂移 * (t - t 历元 ) + D TA-driftvariant * (t - t 历元 ) 2 ,

[0063] where N TA，旧 is the previous N TA value (previous closed-loop component) previously used to determine the previous T TA value.

[0064] In a second implementation for calculating N TA in the closed-loop TA mode, a new MAC-CE with an expanded and / or modified TA command (TAC) range corresponding to the TAC field can be introduced.

[0065] In some such implementations, the bits of the TAC field in the MAC-CE can have a modified granularity and / or step size (e.g., compared to the TAC field used in a previous wireless communication system). In this case, for example, the new N TA value (N TA，新 ) used in the TA calculation formula can be calculated using the following formula:

[0066] N TA-新 = N TA-旧 + (T A - 31) * S * 16 * 64 / 2 μ , where

[0067] NTA-新 is the new N TA value;

[0068] N TA-旧 is the previous N used to determine the previous T TA value (previous closed-loop component); TA value (previous closed-loop component);

[0069] T A is the TAC value found in the TAC field of the MAC-CE (e.g., in the range (0,......, 63));

[0070] S is a scaling factor; and

[0071] μ is the SCS value corresponding to the subcarrier spacing (SCS) used for UL transmission.

[0072] In such cases, the scaling factor S used in this arrangement represents a modification to the granularity and / or step size of the bits of the TAC field as discussed. The scaling factor S can be configured for the UE in the system information block (SIB) or in dedicated RRC signaling.

[0073] In other such embodiments, rather than modifying the granularity and / or step size of the TA command MAC-CE, a larger number of bits are used to allocate the TAC field of the MAC-CE such that it can represent a larger range of values compared to previous wireless communication systems. In such cases, for example, the new N TA value (N TA，新 ) can be calculated using the following formula:

[0074] N TA-新 = N TA-旧 +(T A - 31)*16*64 / 2 μ , where

[0075] N TA-新 is the new N TA value;

[0076] N TA-旧 is the previous N used to determine the previous T TA value; TA value (previous closed-loop component);

[0077] T A is the TAC value found in the TAC field of the MAC-CE (e.g., in the range (0, ……, 255));

[0078] μ is the SCS value corresponding to the subcarrier spacing (SCS) used for UL transmission.

[0079] In such cases, the possible range / quantity that can be represented by the TAC value T A allows N TA (N TA-新 ) to adopt a wider range of values than in previous wireless communication systems.

[0080] In other such embodiments, it may be possible to use both a modified granularity / step size and a larger bit allocation in the TAC field of the MAC-CE. In this case, for example, the new N TA value (N TA，新 ) can be calculated using the following formula:

[0081] N TA-新 = N TA-旧 + (T A - 31) * S * 16 * 64 / 2 μ , where

[0082] N TA-新 is the new N TA value;

[0083] N TA-旧 is the previous N TA value previously used to determine the previous T TA value (previous closed-loop component);

[0084] T A is the TAC value found in the TAC field of the MAC-CE (e.g., in the range (0,......, 255));

[0085] S is the scaling factor; and

[0086] μ is the SCS value corresponding to the subcarrier spacing (SCS) used for UL transmission.

[0087] Note that in some such cases, it is possible / permissible for the scaling factor S = 1.

[0088] In a third embodiment for calculating N TA in the closed-loop TA mode, the TA command can be signaled in the downlink control information (DCI). For example, uplink grant DCI or downlink grant DCI can be used.

[0089] In some cases of such embodiments, the DCI may include a TAC field having the TAC value T A for use at the UE, which is used to determine the new N TA value (N TA，新 ) using the following formula:

[0090] N TA-新 = NTA-旧 +(T A -31)*16*64 / 2 μ , where

[0091] N TA-新 is the new N TA value;

[0092] N TA-旧 is the previous N used to determine the previous T TA value (previous closed-loop component); TA value (previous closed-loop component);

[0093] T A is the TAC value in the TAC field of the DCI; and

[0094] μ is the SCS value corresponding to the subcarrier spacing (SCS) used for UL transmission.

[0095] In other cases of such embodiments, the DCI may use a field (different from the new TAC field) (e.g., an existing one) to provide the UE with the TAC value T A . For example, the DCI may use the most significant bit (MSB) of the modulation and coding scheme (MCS) field of the DCI to convey the TAC value T A . Then, the UE may use the following formula to use the TAC value T A to calculate the new N TA (N TA，新 ): N TA-新 = N TA-旧 +(T A -31)*16*64 / 2 μ (e.g., as just discussed).

[0096] In embodiments where the DCI is used to convey the TA command / TAC value T A , the activation time of the TA command may also be included in the DCI. This activation time may represent, for example, a time value (e.g., X milliseconds) after receiving the DCI (where X may be less than 3 milliseconds, for example).

[0097] Note that cases where the DCI includes other types of information are considered available for calculating the new N TA . For example, it is possible to convey the TA drift rate (D TA-漂移 ), the second derivative of the TA drift (D TA-driftvariant ), and / or higher-order derivatives, and / or the applicable epoch time (t 历元 ) in the DCI (e.g., similar to what was discussed above for the MAC-CE case). In such cases, the new N TA (N TA，新) The value can be determined according to, for example, the following formula: N TA，新 = N TA，旧 + D TA-漂移 *(t - t 历元 ) + D TA-driftvariant *(t - t 历元 ) 2 .

[0098] In some embodiments disclosed herein, the communication used in the closed-loop TA mode may include information for frequency offset control. For example, in some cases, the frequency offset drift rate (including second-order or higher-order drift derivatives) may be provided.

[0099] Figure 3 Timeline 300 corresponding to the use of the GNSS-free operation mode for UE 302 as discussed herein is illustrated, where the UE communicates with base station 304 via a serving link of an NTN network. Timeline 300 illustrates the UE performing a first GNSS acquisition 306 and determining its current location. The UE understands that the location information is valid (e.g., available / applicable) at the UE for the illustrated first validity duration 308.

[0100] UE 302 then performs an initial access 310 to the network / base station 304 and subsequently enters a connected mode 312 with the network / base station 304. When in the connected mode 312, UE 302 first operates according to open-loop and closed-loop TA modes 314, during which it uses the location information determined corresponding to the first GNSS acquisition 306 to drive the open-loop component N TA,UE特定的 , which is used (along with other values) to calculate T during all or part of the first validity duration 308 of the first GNSS acquisition 306 TA .

[0101] Further, after the illustrated second GNSS acquisition 316, the UE may use the corresponding (e.g., updated) location information to drive N during the second validity duration 318 of the second GNSS acquisition 316 TA,UE特定的 , as shown.

[0102] UE 302 then experiences a GNSS acquisition failure 320 due to, for example, failure to receive GNSS signaling and / or failure to receive GNSS signaling of an acceptable quality level / meeting requirements. In response, UE 302 transmits a first request 322 to the base station 304 to enter the closed-loop TA mode (in which GNSS-derived location information is not used to calculate T TA)。In response, the base station 304 transmits a first reply 324 to the UE 302 indicating that the UE may enter the closed-loop TA mode. As illustrated, the first request 322 and the first reply 324 may be transmitted within the second validity duration 318 of the second GNSS acquisition 316 and thus while the UE is still in the open-loop and closed-loop TA mode 314.

[0103] After the expiration of the open-loop and closed-loop TA mode 314 and / or after the expiration of the second validity duration 318, the UE 302 enters the closed-loop TA mode 326, in which GNSS-derived position information is not used to calculate T TA (Instead, the system relies on an enhanced mechanism for generating the closed-loop component N TA to calculate an acceptable T TA (using one or more such mechanisms as described herein)).

[0104] When in the closed-loop TA mode 326, the UE 302 performs a third GNSS acquisition 328, in which GNSS signaling is received (e.g., at an acceptable quality level / upon request), enabling the UE to determine its own position. As illustrated, the third GNSS acquisition 328 corresponds to a third validity duration 330.

[0105] In the case where valid GNSS-derived position data becomes available again at the UE 302, the UE accordingly transmits a second request 332 to the base station 304 to (re)enter the open-loop and closed-loop TA mode (where GNSS-derived position information is used to calculate T TA ). In response, the base station 304 transmits a second reply 334 to the UE 302 indicating that the UE may (re)enter the open-loop and closed-loop TA mode. As illustrated, the second request 332 and the second reply 334 may be transmitted after the third GNSS acquisition 328 and before the UE (re)enters the open-loop and closed-loop TA mode 314.

[0106] Figure 4 Illustrates a procedure 400 for entering and exiting the closed-loop TA mode performed by a UE according to an embodiment herein. The UE may first perform 402 NTN operations using GNSS information for UL synchronization (e.g., T may be calculated according to the open-loop and closed-loop TA mode using GNSS-derived position information) TA ).

[0107] The UE may then detect 404 that a GNSS signal loss has occurred and that it is approaching the end of the GNSS validity duration of the currently used GNSS information.

[0108] Then, the UE may transmit a request 406 to the base station to enter the closed-loop TA mode.

[0109] After receiving confirmation of the closed-loop TA mode from the base station, the UE may move 408 to the closed-loop TA mode.

[0110] The UE may perform 410 NTN operations accordingly without using GNSS information for UL synchronization (e.g., T may be calculated according to the closed-loop TA mode that does not use GNSS-derived position information). TA )

[0111] Then, the UE may detect 412 GNSS signals (e.g., with appropriate quality / meeting requirements) such that GNSS-based position information is established / determinable at the UE again.

[0112] The UE may transmit a request 414 to the base station to (re-)enter the open-loop and closed-loop TA modes.

[0113] After receiving confirmation of the open-loop and closed-loop TA modes from the base station, the UE may move 416 to the open-loop and closed-loop TA modes.

[0114] Finally, the UE may use GNSS information for UL synchronization to perform 418 NTN operations (e.g., T may be calculated according to the open-loop and closed-loop TA modes that use GNSS-derived position information). TA )

[0115] Embodiment of UE Requesting to Enter Closed-Loop TA Mode

[0116] In some embodiments, one or more of various possible trigger conditions for the UE request to enter the closed-loop TA mode may be applied. In one example, the trigger condition may be based on whether the UE has lost / cannot receive GNSS signaling.

[0117] Another trigger condition for the UE to request to enter the closed-loop TA mode may be that the received GNSS signaling does not meet a specific quality level / other requirements.

[0118] Another trigger condition for the UE to request to enter the closed-loop TA mode may be that the time when the validity duration for the current GNSS information expires is approaching / within a certain duration threshold (e.g., the remaining part of the validity duration for the currently GNSS-derived position data at the UE does not meet the threshold).

[0119] For such cases, the applicable threshold for the expiration time of the current GNSS data may depend on, for example, the round-trip time between the UE and the base station.

[0120] Alternatively, the applicable threshold for the expiration time may vary depending on the applicable scenario / classification of the satellite. For example, a relatively low threshold may be used in the case where the UE communicates with a Low Earth Orbit (LEO) satellite, a relatively medium threshold may be used in the case where the UE communicates with a Geostationary Earth Orbit (GEO) satellite, and / or a relatively large threshold may be used in the case where the UE communicates with a Medium Earth Orbit (MEO) satellite.

[0121] Alternatively, the applicable threshold for the expiration time may be based on the timing drift rate (e.g., the downlink (DL) timing drift rate). In such cases, a relatively high timing drift rate may result in the use of a relatively small threshold.

[0122] Another trigger condition for the UE to request entry into the closed-loop TA mode may be based on determining (e.g., at the UE) that the UE is capable of supporting / using the closed-loop TA mode.

[0123] In some cases, the trigger condition for the UE to request entry into the closed-loop TA mode may be based on the UE determining that it has limited power / the UE wants to save power by avoiding receiving GNSS signals. Note that the mechanism triggered by the loss of (sufficient) GNSS signaling discussed herein can be considered to be usable in response to the situation where the GNSS signal is not selected for use by the UE (such as the situation here). In other words, it should be understood that, for example, Figure 3 the GNSS acquisition failure 320 and / or Figure 4 the detection 404 of GNSS signal loss can be functionally replaced by the UE determining to enter the power saving mode and accordingly transmitting a request to enter the closed-loop TA mode (corresponding to the UE choosing not to use the GNSS signal).

[0124] The request to enter the closed-loop TA mode may include one or more of the following: the GNSS expiration timing, or the time when the UE moves to the RRC_IDLE state if no response to the request is received (this value may depend on the UE implementation); an (explicit) request to enter the closed-loop TA mode; the current timing information at the UE; the last measured GNSS position and / or GNSS measurement time at the UE; and / or the GNSS position lock duration (the desired minimum duration of the closed-loop TA mode).

[0125] The request to enter the closed-loop TA mode may be transmitted in any one of, for example, MAC-CE signaling, RRC signaling, and / or uplink control information (UCI).

[0126] Embodiment of Base Station Replying to UE's Request to Enter Closed-Loop TA Mode

[0127] In some embodiments, the response of the base station to a request from the UE to enter the closed-loop TA mode may include one or more of the following: the timing of the action to enter the closed-loop TA mode; a TAC field with a TAC value (T A ), including, for example, a TAC field using a modified granularity / step size and / or a larger bit allocation, as described elsewhere herein); frequency offset information; and / or the maximum possible duration for operating in the closed-loop TA mode (which implicitly indicates that the UE will move to, for example, the RRC_IDLE state and / or the RRC_INACTIVE state after operating in the closed-loop TA mode for that duration).

[0128] The reply to the request to enter the closed-loop TA mode may be transmitted in any one of, for example, MAC-CE signaling, RRC signaling, and / or DCI.

[0129] In some cases, if no reply is received before the expiration of the applicable validity duration of the currently used GNSS information, the UE moves to the RRC_IDLE state and / or the RRC_INACTIVE state. In other cases, if no reply is received before the expiration of the validity duration of the currently used GNSS information, the UE may receive an RRC release including an RRC connection failure and a message cause of "GNSS signal lost" from the base station.

[0130] Embodiment of UE Requesting to Exit Closed-Loop TA Mode

[0131] In some examples, the trigger condition for the UE to request to exit the closed-loop TA mode (e.g., (re)enter the open-loop and closed-loop TA modes) may be that the UE (re)acquires GNSS signaling that meets certain quality requirements.

[0132] The request to exit the closed-loop TA mode may include the validity duration for the new GNSS position lock.

[0133] The request to exit the closed-loop TA mode may be transmitted in any one of, for example, MAC-CE signaling, RRC signaling, and / or UCI.

[0134] Embodiment of Base Station Replying to UE's Request to Exit Closed-Loop TA Mode

[0135] In some embodiments, the response of the base station to the UE's request to exit the closed-loop TA mode may include the timing of the action to exit the closed-loop TA mode.

[0136] The reply to the request to exit the closed-loop TA mode may be transmitted in any one of, for example, MAC-CE signaling, RRC signaling, and / or DCI.

[0137] Figure 5Method 500 of a UE of an NTN exemplifying embodiments discussed herein. Method 500 includes UE identifying 502 GNSS data acquisition failure. Method 500 further includes, in response to the GNSS data acquisition failure, transmitting 504 to a base station of the NTN network a first request for transitioning from operating in a first TA mode to operating in a second TA mode, wherein the UE determines a first TA value for the UE using first GNSS data determined at the UE according to the first TA mode, and the UE determines a second TA value for the UE without using any GNSS data according to the second TA mode. Method 500 further includes receiving 506 from the base station a first reply indicating that the UE is capable of transitioning from operating in the first TA mode to operating in the second TA mode. Method 500 further includes, in response to the reply, transitioning 508 from operating in the first TA mode to operating in the second TA mode. Method 500 further includes determining 510 that method 500 uses the second TA value to determine the timing of UL transmission. Method 500 further includes transmitting 512 the UL transmission to the base station according to the timing.

[0138] In some embodiments, to determine the second TA value according to the second TA mode, method 500 further includes: receiving from the base station a MAC-CE that includes a TA drift rate of TA drift, a higher-order derivative of TA drift, and an epoch time; and using the TA drift rate, the higher-order derivative of TA drift, and the epoch time to calculate a closed-loop component of the second TA value [1].

[0139] In some embodiments, to determine the second TA value according to the second TA mode, method 500 further includes: receiving from the base station a MAC-CE having a TAC field with more than six bits; and using the TAC value represented in the TAC field to calculate a closed-loop component of the second TA value.

[0140] In some embodiments, to determine the second TA value according to the second TA mode, method 500 further includes: receiving a MAC-CE including a TAC value; and using the following formula to calculate a closed-loop component of the second TA value:

[0141] N TA-新 =N TA-旧 +(T A -31)*S*16*64 / 2 μ where:

[0142] N TA-新 is the closed-loop component of the second TA value; N TA-旧 is the previous closed-loop component of the first TA value; T A is the TAC value; S is a scaling factor; and μ is the SCS value corresponding to the subcarrier spacing (SCS) used for UL transmission.

[0143] In some embodiments, to determine a second TA value according to a second TA mode, method 500 further includes: receiving, from a base station, a DCI including a TAC field; and using the TAC value indicated in the TAC field to calculate a closed-loop component of the second TA value.

[0144] In some embodiments, to determine a second TA value according to a second TA mode, method 500 further includes: receiving, from a base station, a DCI that includes a TAC value in an MCS field of the DCI; and using the TAC value to calculate a closed-loop component of the second TA value.

[0145] In some embodiments, to determine a second TA value according to a second TA mode, method 500 further includes: receiving, from a base station, a DCI that includes a TA drift rate of TA drift, a higher-order derivative of TA drift, and an epoch time; and using the TA drift rate, the higher-order derivative of TA drift, and the epoch time to calculate a closed-loop component of the second TA value.

[0146] In some embodiments of method 500, GNSS data acquisition failure includes loss of GNSS signals at the UE.

[0147] In some embodiments of method 500, GNSS data acquisition failure includes determining that the received GNSS signals at the UE do not meet the GNSS signal requirements.

[0148] In some embodiments of method 500, the first request is further transmitted in response to determining that the remaining portion of the GNSS data validity duration of the first GNSS data at the UE does not meet a threshold. In some such embodiments, the threshold depends on one or more of the following: the RTT between the UE and the base station; the distance between the UE and the NTN vehicle for the NTN service link used by the UE to communicate with the base station; and the timing drift rate at the UE.

[0149] In some embodiments of method 500, the first request includes one or more of the following: the expiration time of the GNSS data validity duration of the first GNSS data; the last GNSS measurement location of the UE; and the desired minimum duration for operating in the second TA mode.

[0150] In some embodiments of method 500, the first reply includes one or more of the following: the timing for transitioning from the first TA mode to the second TA mode; the TAC value; and the maximum duration for operating in the second TA mode.

[0151] In some embodiments, method 500 further includes: after entering the second TA mode, identifying successful GNSS data acquisition of second GNSS data at the UE; in response to the successful GNSS data acquisition of the second GNSS data, transmitting a second request to the base station for transitioning from operating in the second TA mode to operating in the first TA mode, wherein the UE uses the second GNSS data according to the first TA mode to determine a third TA value for the UE; receiving a second reply from the base station, the second reply indicating that the UE is capable of transitioning from operating in the second TA mode to operating in the first TA mode; and in response to the second reply, transitioning from operating in the second TA mode to operating in the first TA mode. In some such embodiments, the second request includes the GNSS data validity duration of the second GNSS data. In some such embodiments, the second reply includes the timing for transitioning from the second TA mode to the first TA mode.

[0152] In some embodiments of method 500, the first TA mode is an open-loop and closed-loop TA mode.

[0153] In some embodiments of method 500, the second TA mode is a closed-loop TA mode.

[0154] Figure 6 Method 600 of a base station of an NTN according to embodiments discussed herein is illustrated. Method 600 includes receiving 602 from a UE a first request for transitioning from operating in a first TA mode to operating in a second TA mode, wherein the UE uses first GNSS data determined at the UE according to the first TA mode to determine a first TA value for the UE, and the UE determines a second TA value for the UE without using any GNSS data according to the second TA mode. Method 600 further includes transmitting 604 to the UE a first reply, the first reply indicating that the UE is capable of transitioning from operating in the first TA mode to operating in the second TA mode. Method 600 further includes receiving 606 a UL transmission from the UE after transmitting the first reply.

[0155] In some embodiments, method 600 further includes transmitting to the UE a MAC-CE, the MAC-CE including a TA drift rate of TA drift, a higher-order derivative of TA drift, and an epoch time.

[0156] In some embodiments, method 600 further includes transmitting to the UE a MAC-CE having a TAC field with more than six bits).

[0157] In some embodiments, method 600 further includes transmitting to the UE a MAC-CE including a TAC value, the TAC value being configured to calculate a closed-loop component of the second TA value at the UE using the following formula:

[0158] N TA-新 =NTA-旧 +(T A - 31)*S*16*64 / 2 μ , where:

[0159] N TA-新 is the closed - loop component of the second TA value; N TA-旧 is the previous closed - loop component of the first TA value; T A is the TAC value; S is the scaling factor; and μ is the SCS value corresponding to the sub - carrier spacing (SCS) used for UL transmission.

[0160] In some embodiments, method 600 further includes transmitting to the UE a DCI including a TAC field.

[0161] In some embodiments, method 600 further includes transmitting to the UE a DCI that includes the TAC value in the MCS field of the DCI.

[0162] In some embodiments, method 600 further includes transmitting to the UE a DCI that includes the TA drift rate of the TA drift, the higher - order derivative of the TA drift, and the epoch time.

[0163] In some embodiments of method 600, the first request includes one or more of the following: the expiration time of the GNSS data validity duration of the first GNSS data; the last GNSS measurement location of the UE; and the desired minimum duration for operating in the second TA mode.

[0164] In some embodiments of method 600, the first reply includes one or more of the following: the timing for transitioning from the first TA mode to the second TA mode; the TAC value; and the maximum duration for operating in the second TA mode.

[0165] In some embodiments, method 600 further includes: receiving from the UE a second request for transitioning from operating in the second TA mode to operating in the first TA mode, wherein the UE determines a third TA value for the UE according to the first TA mode using second GNSS data; and transmitting to the UE a second reply indicating that the UE can transition from operating in the second TA mode to operating in the first TA mode. In some such embodiments, the second request includes the GNSS data validity duration of the second GNSS data.

[0166] Figure 7Method 700 of a UE of an NTN exemplifying an embodiment discussed herein. Method 700 includes determining 702 to implement a power saving mode at the UE. Method 700 further includes transmitting 704 to a base station of the NTN network a first request for transitioning from operating in a first TA mode to operating in a second TA mode in response to determining to implement the power saving mode at the UE, wherein the UE determines a first TA value for the UE using first GNSS data determined at the UE according to the first TA mode, and the UE determines a second TA value for the UE without using any GNSS data according to the second TA mode. Method 700 further includes receiving 706 a first reply from the base station, the first reply indicating that the UE is capable of transitioning from operating in the first TA mode to operating in the second TA mode. Method 700 further includes transitioning 708 from operating in the first TA mode to operating in the second TA mode in response to the reply. Method 700 further includes determining 710 the timing of UL transmission using the second TA value. Method 700 further includes transmitting 712 the UL transmission to the base station according to the timing.

[0167] In some embodiments, to determine the second TA value according to the second TA mode, method 700 further includes: receiving from the base station a MAC-CE that includes a TA drift rate of TA drift, a higher-order derivative of TA drift, and an epoch time; and using the TA drift rate, the higher-order derivative of TA drift, and the epoch time to calculate a closed-loop component of the second TA value [1].

[0168] In some embodiments, to determine the second TA value according to the second TA mode, method 700 further includes: receiving from the base station a MAC-CE having a TAC field with more than six bits; and using the TAC value represented in the TAC field to calculate a closed-loop component of the second TA value.

[0169] In some embodiments, to determine the second TA value according to the second TA mode, method 700 further includes: receiving a MAC-CE that includes a TAC value; and calculating a closed-loop component of the second TA value using the following formula:

[0170] N TA-新 =N TA-旧 +(T A -31)*S*16*64 / 2 μ , where:

[0171] N TA-新 is the closed-loop component of the second TA value; N TA-旧 is the previous closed-loop component of the first TA value; T A is the TAC value; S is a scaling factor; and μ is the SCS value corresponding to the subcarrier spacing (SCS) used for UL transmission.

[0172] In some embodiments, to determine a second TA value according to a second TA mode, method 700 further includes: receiving, from a base station, a DCI including a TAC field; and using the TAC value indicated in the TAC field to calculate a closed-loop component of the second TA value.

[0173] In some embodiments, to determine a second TA value according to a second TA mode, method 700 further includes: receiving, from a base station, a DCI that includes a TAC value in an MCS field of the DCI; and using the TAC value to calculate a closed-loop component of the second TA value.

[0174] In some embodiments, to determine a second TA value according to a second TA mode, method 700 further includes: receiving, from a base station, a DCI that includes a TA drift rate of TA drift, a higher-order derivative of TA drift, and an epoch time; and using the TA drift rate, the higher-order derivative of TA drift, and the epoch time to calculate a closed-loop component of the second TA value.

[0175] In some embodiments of method 700, determining to implement a power saving mode at a UE is based on the UE's battery level.

[0176] In some embodiments of method 700, the first request includes one or more of the following: an expiration time of a GNSS data validity duration of first GNSS data; a last GNSS measurement location of the UE; and a desired minimum duration for operating in a second TA mode.

[0177] In some embodiments of method 700, the first reply includes one or more of the following: a timing for transitioning from a first TA mode to a second TA mode; a TAC value; and a maximum duration for operating in a second TA mode.

[0178] In some embodiments, method 700 further includes: after entering the second TA mode, identifying a successful GNSS data acquisition of second GNSS data at the UE; in response to the successful GNSS data acquisition of the second GNSS data, transmitting, to the base station, a second request for transitioning from operating in the second TA mode to operating in the first TA mode, wherein the UE determines a third TA value for the UE using the second GNSS data according to the first TA mode; receiving, from the base station, a second reply that indicates that the UE is capable of transitioning from operating in the second TA mode to operating in the first TA mode; and in response to the second reply, transitioning from operating in the second TA mode to operating in the first TA mode. In some such embodiments, the second request includes a GNSS data validity duration of the second GNSS data. In some such embodiments, the second reply includes a timing for transitioning from the second TA mode to the first TA mode.

[0179] In some embodiments of method 700, the first TA mode is an open-loop and a closed-loop TA mode.

[0180] In some embodiments of method 700, the second TA mode is a closed-loop TA mode.

[0181] Figure 8 An example architecture of a wireless communication system 800 in accordance with embodiments disclosed herein is illustrated. The description provided below is for an example wireless communication system 800 operating in conjunction with the LTE system standard and / or the 5G or NR system standard provided in 3GPP technical specifications and other 3GPP documents.

[0182] As Figure 8 shown, the wireless communication system 800 includes UEs 802 and 804 (however, any number of UEs may be used). In this example, UEs 802 and 804 are illustrated as smartphones (e.g., handheld touchscreen mobile computing devices capable of connecting to one or more cellular networks), but may also include any mobile or non-mobile computing device configured for wireless communication.

[0183] UEs 802 and 804 may be configured to be communicatively coupled to RAN 806. In an embodiment, RAN 806 may be an NG-RAN, an E-UTRAN, etc. UEs 802 and 804 utilize connections (or channels) with RAN 806 (shown as connections 808 and 810, respectively), where each connection (or channel) includes a physical communication interface. RAN 806 may include one or more base stations (such as terrestrial base stations 812, terrestrial base stations 814, satellite base stations 836, and satellite base stations 838) and / or other entities enabling connections 808 and 810 (e.g., satellite 842 that may not have base station functionality). One or more satellite gateways 834 may integrate satellite base stations 836, satellite base stations 838, and / or satellite 842 into RAN 806 in the manner (and with appropriate elements) described with respect to Figure 1 NTN architecture 100 and Figure 2 NTN architecture 200.

[0184] It should be understood that in Figure 8 an alternative embodiment, satellite base stations 836, satellite base stations 838, and / or satellite 842 may instead include non-satellite NTN vehicles (e.g., airplanes, UAVs, UASs, airships, balloons, etc.). Further, it should be understood that in such alternative embodiments, any satellite gateway 834 may be a gateway for or corresponding to the applicable NTN vehicle type.

[0185] In this example, connections 808 and 810 are air interfaces that enable such communication coupling and may conform to the RAT used by RAN 806, such as, for example, LTE and / or NR. It is contemplated that in some embodiments, connections 808 and 810 may include service links between one or more of their respective UEs 802, UE 804, and satellite base stations 836, satellite base stations 838, and satellite 842.

[0186] In some embodiments, UEs 802 and 804 may also directly communicate and exchange data via the sidelink interface 816.

[0187] UE 804 is shown configured to access an access point (shown as AP 818) via connection 820. For example, connection 820 may include a local wireless connection, such as any connection conforming to the IEEE 802.11 protocol, where AP 818 may include a router. In this example, AP 818 may not be connected to another network (e.g., the Internet) via CN 824.

[0188] In embodiments, UEs 802 and 804 may be configured to communicate with each other over a multi-carrier communication channel using orthogonal frequency division multiplexing (OFDM) communication signals according to various communication techniques, such as, but not limited to, orthogonal frequency division multiple access (OFDMA) communication techniques (e.g., for downlink communication) or single carrier frequency division multiple access (SC-FDMA) communication techniques (e.g., for uplink and ProSe or sidelink communication), with terrestrial base stations 812, terrestrial base stations 814, satellite base stations 836, satellite base stations 838, and / or satellite 842, although the scope of the embodiments is not limited in this regard. The OFDM signal may include a plurality of orthogonal subcarriers.

[0189] In some embodiments, all or part of terrestrial base stations 812, terrestrial base stations 814, satellite base stations 836, and / or satellite base stations 838 may be implemented as one or more software entities running on a server computer as part of a virtual network.

[0190] Additionally, or in other embodiments, terrestrial base station 812 or terrestrial base station 814 may be configured to communicate with each other via interface 822. In an embodiment where the wireless communication system 800 is an LTE system (e.g., when CN 824 is an EPC), interface 822 may be an X2 interface. The X2 interface may be defined between two or more base stations connected to the EPC (e.g., two or more eNBs, etc.) and / or between two eNBs connected to the EPC. It is contemplated that an inter-satellite link (ISL) may carry the X2 interface between two satellite base stations.

[0191] In an implementation where the wireless communication system 800 is an NR system (e.g., when the CN 824 is a 5GC), the interface 822 can be an Xn interface. The Xn interface is defined between two or more base stations connected to the 5GC (e.g., CN 824). For example, the Xn interface can be between two or more gNBs connected to the 5GC, between a gNB and an eNB connected to the 5GC, between two eNBs connected to the 5GC, and / or between two or more satellite base stations via an ISL (e.g., such as the interface 840 between satellite base station 836 and satellite base station 838).

[0192] It is shown that the RAN 806 is communicatively coupled to the CN 824. The CN 824 can include one or more network elements 826, which are configured to provide various data and telecommunications services to customers / subscribers (e.g., users of UEs 802 and 804) connected to the CN 824 via the RAN 806. The components of the CN 824 can be implemented in one physical device or in respective independent physical devices including components for reading and executing instructions from a machine-readable or computer-readable medium (e.g., a non-transitory machine-readable storage medium). For example, the components of the CN 824 can be implemented as being in one or more processors and / or one or more associated memories.

[0193] In an implementation, the CN 824 can be an EPC, and the RAN 806 can be connected to the CN 824 via an S1 interface 828. In an implementation, the S1 interface 828 can be divided into two parts: an S1 user plane (S1-U) interface, which carries traffic data between the terrestrial base stations 812, 814, the satellite base station 836, or the interface 840 and the serving gateway (S-GW); and an S1-MME interface, which is a signaling interface between the terrestrial base stations 812, 814, the satellite base station 836, or the interface 840 and the mobility management entity (MME).

[0194] In an implementation, the CN 824 can be a 5GC, and the RAN 806 can be connected to the CN 824 via an NG interface 828. In an implementation, the NG interface 828 can be divided into two parts: an NG user plane (NG-U) interface, which carries traffic data between the terrestrial base stations 812, 814, the satellite base station 836, or the satellite base station 838 and the user plane function (UPF); and an S1 control plane (NG-C) interface, which is a signaling interface between the terrestrial base stations 812, 814, the satellite base station 836, or the satellite base station 838 and the access and mobility management function (AMF).

[0195] Generally, the application server 830 can be an element that provides an application for using Internet Protocol (IP) bearer resources together with the CN 824 (e.g., a packet switched data service). The application server 830 can also be configured to support one or more communication services (e.g., VoIP sessions, group communication sessions, etc.) for the UEs 802 and 804 via the CN 824. The application server 830 can communicate with the CN 824 through the IP communication interface 832.

[0196] Figure 9 Illustrated is a system 900 for performing signaling 934 between a wireless device 902 and a RAN device 918 according to an embodiment disclosed herein. The system 900 can be part of a wireless communication system as described herein. The wireless device 902 can be, for example, a UE of a wireless communication system. The RAN device 918 can be, for example, a base station of a wireless communication system (e.g., an eNB or a gNB), which is a terrestrial base station or a non-terrestrial base station located on an NTN vehicle. In the case where the RAN device 918 is a terrestrial base station, the RAN device 918 can communicate with an NTN vehicle that directly provides a radio access connection to the UE in the manner described herein.

[0197] The wireless device 902 can include one or more processors 904. The processor 904 can execute instructions to perform various operations of the wireless device 902 as described herein. The processor 904 can include one or more baseband processors, which are implemented using, for example, a central processing unit (CPU), a digital signal processor (DSP), an application specific integrated circuit (ASIC), a controller, a field programmable gate array (FPGA) device, another hardware device, a firmware device, or any combination thereof configured to perform the operations described herein.

[0198] The wireless device 902 can include a memory 906. The memory 906 can be a non-transitory computer-readable storage medium that stores instructions 908 (which can include, for example, instructions executed by the processor 904). The instructions 908 can also be referred to as program code or a computer program. The memory 906 can also store data used by the processor 904 and results calculated by the processor.

[0199] Wireless device 902 may include one or more transceivers 910, which may include radio frequency (RF) transmitter and / or receiver circuitry that uses antenna 912 of wireless device 902 to facilitate signaling (e.g., signaling 934) transmission between wireless device 902 and other devices (e.g., RAN device 918) according to the corresponding RAT. In some embodiments, antenna 912 may include a mobile parabolic antenna, an omnidirectional phased array antenna, or some other antenna suitable for communicating with an NTN vehicle (e.g., as described above with respect to Figure 1 UE 110 and Figure 2 UE 208).

[0200] For RAN device 918 that is a terrestrial base station, network device signaling 934 may occur on the serving link between wireless device 902 and the NTN vehicle and on the feeder link between the NTN vehicle and RAN device 918 (e.g., as described with respect to Figure 1 ). For RAN device 918 that is a base station located on an NTN vehicle, signaling 934 may occur on the serving link between wireless device 902 and RAN device 918 (e.g., as described with respect to Figure 2 ).

[0201] Wireless device 902 may include one or more antennas 912 (e.g., one, two, four, or more). For embodiments with multiple antennas 912, wireless device 902 may take full advantage of the spatial diversity of these multiple antennas 912 to transmit and / or receive multiple different data streams on the same time-frequency resource. This behavior may be referred to as, for example, multiple-input multiple-output (MIMO) behavior (referring to the multiple antennas used at each of the transmitting device and the receiving device to achieve this aspect). MIMO transmission performed by wireless device 902 may be implemented according to pre-coding (or digital beamforming) applied to wireless device 902, and wireless device 902 multiplexes data streams between antennas 912 based on known or assumed channel characteristics such that each data stream is received with an appropriate signal strength relative to other streams and at a desired location in the spatial domain (e.g., the location of the receiver associated with that data stream). Certain embodiments may use single-user MIMO (SU-MIMO) methods (where the data streams are all directed to a single receiver) and / or multi-user MIMO (MU-MIMO) methods (where individual data streams may be directed to separate (different) receivers at different locations in the spatial domain).

[0202] In some embodiments with multiple antennas, the wireless device 902 may implement analog beamforming techniques, whereby the phases of the signals transmitted by the antennas 912 are adjusted relative to each other such that the (joint) transmission of the antennas 912 has directivity (which is sometimes referred to as beam steering).

[0203] The wireless device 902 may include one or more interfaces 914. The interfaces 914 can be used to provide input to or output from the wireless device 902. For example, the wireless device 902 as a UE may include interfaces 914 such as a microphone, a speaker, a touch screen, buttons, etc. to allow a user of the UE to provide input to and / or output from the UE. Other interfaces of such a UE may consist of transmitters, receivers, and other circuitry (e.g., other than the transceiver 910 / antenna 912 already described) that allow the UE to communicate with other devices and may operate according to known protocols (e.g., etc.).

[0204] The wireless device 902 may include a TA mode configuration module 916. The TA mode configuration module 916 may be implemented via hardware, software, or a combination thereof. For example, the TA mode configuration module 916 may be implemented as a processor, circuitry, and / or instructions 908 stored in the memory 906 and executed by the processor 904. In some examples, the TA mode configuration module 916 may be integrated within the processor 904 and / or the transceiver 910. For example, the TA mode configuration module 916 may be implemented by a combination of software components (e.g., executed by a DSP or a general-purpose processor) and hardware components (e.g., logic gates and circuitry) within the processor 904 or the transceiver 910.

[0205] The TA mode configuration module 916 may be used in various aspects of the present disclosure, for example, Figure 5 and / or Figure 7 aspects of. The TA mode configuration module 916 may configure the wireless device 902 to, for example, transmit a request to enter a closed-loop TA mode to the RAN device 918, receive a reply from the RAN device 918 indicating that the wireless device 902 may enter the closed-loop TA mode, calculate a timing advance value according to the closed-loop TA mode (e.g., using information received from the RAN device 918, transmit a request to enter open-loop and closed-loop TA modes to the RAN device 918, receive a reply from the RAN device 918 indicating that the wireless device 902 may enter open-loop and closed-loop TA modes, and / or calculate a timing advance value according to open-loop and closed-loop TA modes (e.g., using information received from the RAN device 918, as described herein.

[0206] The RAN device 918 may include one or more processors 920. The processor 920 may execute instructions to perform various operations of the RAN device 918 as described herein. The processor 904 may include one or more baseband processors implemented using, for example, a CPU, a DSP, an ASIC, a controller, an FPGA device, another hardware device, a firmware device, or any combination thereof configured to perform the operations described herein.

[0207] The RAN device 918 may include a memory 922. The memory 922 may be a non-transitory computer-readable storage medium for storing instructions 924 (which may include, for example, instructions executed by the processor 920). The instructions 924 may also be referred to as program code or a computer program. The memory 922 may also store data used by the processor 920 and results calculated by the processor.

[0208] The RAN device 918 may include one or more transceivers 926, which may include RF transmitter and / or receiver circuitry that uses the antennas 928 of the RAN device 918 to facilitate the transmission of signaling (e.g., signaling 934) between the RAN device 918 and other devices (e.g., the wireless device 902) according to the corresponding RAT.

[0209] The RAN device 918 may include one or more antennas 928 (e.g., one, two, four, or more). In embodiments having multiple antennas 928, the RAN device 918 may perform MIMO, digital beamforming, analog beamforming, beam control, etc. as described above.

[0210] For the RAN device 918 that is a terrestrial base station, one or more of the transceivers 926 and / or antennas 928 may instead be present on a satellite gateway associated with the base station (or a gateway for another applicable NTN vehicle type) (e.g., as shown for the terrestrial base station 104 and the satellite gateway 106 in reference Figure 1 For the RAN device 918 that is a base station located on an NTN vehicle, the transceivers 926 and / or antennas 928 may be present on the NTN vehicle, and one or more of those antennas 928 may be antennas suitable for non-terrestrial communication (such as a mobile parabolic antenna, an omnidirectional phased array antenna, etc.).

[0211] The RAN device 918 may include one or more interfaces 930. The interface 930 can be used to provide input to or output from the RAN device 918. For example, the RAN device 918 acting as a base station may include an interface 930 composed of a transmitter, a receiver, and other circuits (e.g., in addition to the transceiver 926 / antenna 928 already described), which enables the base station to communicate with other equipment in the CN and / or enables the base station to communicate with an external network, a computer, a database, etc., for the purpose of performing operations, managing, and maintaining the base station or other equipment operably connected thereto.

[0212] The RAN device 918 may include a TA mode configuration module 932. The TA mode configuration module 932 can be implemented via hardware, software, or a combination thereof. For example, the TA mode configuration module 932 can be implemented as a processor, a circuit, and / or instructions 924 stored in the memory 922 and executed by the processor 920. In some examples, the TA mode configuration module 932 may be integrated within the processor 920 and / or the transceiver 926. For example, the TA mode configuration module 932 can be implemented by a combination of software components (e.g., executed by a DSP or a general-purpose processor) and hardware components (e.g., logic gates and circuits) within the processor 920 or the transceiver 926.

[0213] The TA mode configuration module 932 can be used in various aspects of the present disclosure, such as Figure 6 the aspects described herein. The TA mode configuration module 932 can configure the RAN device 918 to, for example, receive a request to enter the closed-loop TA mode from the wireless device 902, transmit a reply to the wireless device 902 indicating that the wireless device 902 can enter the closed-loop TA mode, transmit information to the wireless device 902 that enables the wireless device 902 to calculate a timing advance value using the closed-loop TA mode, receive a request to enter the open-loop and closed-loop TA modes from the wireless device 902, transmit a reply to the wireless device 902 indicating that the wireless device 902 can enter the open-loop and closed-loop TA modes, and / or transmit information to the wireless device 902 that enables the wireless device 902 to calculate a timing advance value using the open-loop and closed-loop TA modes, as described herein.

[0214] The embodiments contemplated herein include an apparatus that includes means for performing one or more elements of any one of method 500 and / or method 700. The apparatus can be, for example, an apparatus of a UE (such as the wireless device 902 acting as a UE, as described herein).

[0215] The embodiments contemplated herein include one or more non-transitory computer-readable media that include instructions that, when executed by one or more processors of an electronic device, cause the electronic device to perform one or more elements of any one of Method 500 and / or Method 700. The non-transitory computer-readable media can be, for example, the memory of a UE (such as the memory 906 of the wireless device 902 of the UE as described herein).

[0216] The embodiments contemplated herein include an apparatus that includes logic components, modules, or circuits for performing one or more elements of any one of Method 500 and / or Method 700. The apparatus can be, for example, an apparatus of a UE (such as the wireless device 902 of the UE as described herein).

[0217] The embodiments contemplated herein include an apparatus that includes: one or more processors and one or more computer-readable media that include instructions that, when executed by the one or more processors, cause the one or more processors to perform one or more elements of any one of Method 500 and / or Method 700. The apparatus can be, for example, an apparatus of a UE (such as the wireless device 902 of the UE as described herein).

[0218] The embodiments contemplated herein include a signal as described in or related to one or more elements of any one of Method 500 and / or Method 700.

[0219] The embodiments contemplated herein include a computer program or computer program product that includes instructions, where execution of the program by a processor causes the processor to perform one or more elements of any one of Method 500 and / or Method 700. The processor can be a processor of a UE (such as the processor 904 of the wireless device 902 of the UE as described herein). The instructions can be, for example, located in and / or on the memory of the UE (such as the memory 906 of the wireless device 902 of the UE as described herein).

[0220] The embodiments contemplated herein include an apparatus that includes components for performing one or more elements of Method 600. The apparatus can be, for example, an apparatus of a base station (such as the RAN device 918 of the base station as described herein).

[0221] The embodiments contemplated herein include one or more non-transitory computer-readable media that include instructions which, when executed by one or more processors of an electronic device, cause the electronic device to perform one or more elements of method 600. The non-transitory computer-readable media can be, for example, the memory of a base station (such as the memory 922 of the RAN device 918 that is the base station, as described herein).

[0222] The embodiments contemplated herein include an apparatus that includes logic components, modules, or circuits for performing one or more elements of method 600. The apparatus can be, for example, the apparatus of a base station (such as the RAN device 918 that is the base station, as described herein).

[0223] The embodiments contemplated herein include an apparatus that includes: one or more processors and one or more computer-readable media that include instructions which, when executed by the one or more processors, cause the one or more processors to perform one or more elements of method 600. The apparatus can be, for example, the apparatus of a base station (such as the RAN device 918 that is the base station, as described herein).

[0224] The embodiments contemplated herein include a signal as described in or related to one or more elements of method 600.

[0225] The embodiments contemplated herein include a computer program or computer program product that includes instructions, where execution of the program by a processing element causes the processing element to perform one or more elements of method 600. The processor can be the processor of a base station (such as the processor 920 of the RAN device 918 that is the base station, as described herein). The instructions can be, for example, located in the processor and / or on the memory of the base station (such as the memory 922 of the RAN device 918 that is the base station, as described herein).

[0226] For one or more embodiments, at least one of the components set forth in one or more of the foregoing figures can be configured to perform one or more operations, techniques, processes, and / or methods as set forth herein. For example, as described herein in connection with one or more of the foregoing figures, a baseband processor can be configured to operate according to one or more of the examples set forth herein. As another example, circuits associated with a UE, base station, network element, etc., as described above in connection with one or more of the foregoing figures, can be configured to operate according to one or more of the examples set forth herein.

[0227] Unless otherwise expressly stated, any one of the above-described embodiments may be combined with any other embodiment (or combination of embodiments). The foregoing description of one or more specific embodiments provides illustration and description, but is not intended to be exhaustive or to limit the scope of the embodiments to the precise forms disclosed. Modifications and variations are possible in light of the above teachings, or may be acquired from practice of various embodiments.

[0228] Embodiments and specific implementations of the systems and methods described herein may include various operations, which may be embodied in machine-executable instructions to be executed by a computer system. The computer system may include one or more general-purpose or special-purpose computers (or other electronic devices). The computer system may include hardware components that include specific logic components for performing the operations; or may include a combination of hardware, software, and / or firmware.

[0229] It should be recognized that the systems described herein include a description of specific embodiments. These embodiments may be combined into a single system, partially combined into other systems, divided into multiple systems, or otherwise partitioned or combined. In addition, it is contemplated that the parameters, properties, aspects, etc. of one embodiment may be used in another embodiment. For clarity, these parameters, properties, aspects, etc. are described in only one or more embodiments, and it should be recognized that, unless expressly stated herein, these parameters, properties, aspects, etc. may be combined with or substituted for the parameters, properties, aspects, etc. of another embodiment.

[0230] It is well known that the use of personally identifiable information should follow privacy policies and practices that are generally recognized to meet or exceed industry or government requirements for maintaining user privacy. Specifically, personally identifiable information data should be managed and processed to minimize the risk of inadvertent or unauthorized access or use, and the nature of authorized use should be clearly explained to users.

[0231] Although the foregoing has been described in considerable detail for purposes of clarity, it will be apparent that certain changes and modifications may be made without departing from the principles of the invention. It should be noted that there are many alternative ways of implementing both the processes and apparatus described herein. Accordingly, the embodiments of the invention should be regarded as illustrative rather than restrictive, and the specification is not limited to the details given herein, but may be modified within the scope and equivalents of the appended claims.

Claims

1. A method for a user equipment (UE) of a non-terrestrial network (NTN), the method comprising: The UE identifies a failure in acquiring global navigation satellite system (GNSS) data; In response to the GNSS data acquisition failure, transmitting to a base station of the NTN network a first request for transitioning from operating in a first timing advance (TA) mode to operating in a second TA mode, the UE determining a first TA value for the UE using first GNSS data determined at the UE according to the first TA mode, the UE determining a second TA value for the UE according to the second TA mode without using any GNSS data; as well as receiving a first reply from the base station, the first reply indicating that the UE can transition from operating in the first TA mode to operating in the second TA mode; in response to the reply, transitioning from operating in the first TA mode to operating in the second TA mode; determining timing of uplink (UL) transmissions using the second TA value; as well as The UL transmission is transmitted to the base station according to the timing.

2. The method according to claim 1, wherein in order to determine the second TA value according to the second TA mode, the method further comprises: receiving a medium access control element (MAC-CE) from the base station, the medium access control element (MAC-CE) including a TA drift rate of a TA drift, a high order derivative of the TA drift, and an epoch time; as well as A closed-loop component of the second TA value is calculated using the TA drift rate, the high-order derivatives of the TA drift, and the epoch time.

3. The method according to claim 1, wherein in order to determine the second TA value according to the second TA mode, the method further comprises: receiving a medium access control element (MAC-CE) having a timing advance command (TAC) field greater than six bits from the base station; as well as A closed-loop component of the second TA value is calculated using the TAC value represented in the TAC field.

4. The method according to claim 1, wherein in order to determine the second TA value according to the second TA mode, the method further comprises: receiving a medium access control element (MAC-CE) including a timing advance command (TAC) value; as well as The closed-loop component of the second TA value is calculated using the following equation: N TA-新 =N TA-旧 +(T A -31)*S*16*64 / 2 μ ,in: N TA-新 is the closed-loop component of the second TA value; N TA-旧 is the previous closed-loop component of the first TA value; T A is the TAC value; S is the scaling factor; as well as μ is a subcarrier spacing (SCS) value corresponding to the SCS used for the UL transmission.

5. The method according to claim 1, wherein in order to determine the second TA value according to the second TA mode, the method further comprises: receiving downlink control information (DCI) including a timing advance command (TAC) field from the base station; as well as A closed-loop component of the second TA value is calculated using the TAC value represented in the TAC field.

6. The method according to claim 1, wherein in order to determine the second TA value according to the second TA mode, the method further comprises: receiving downlink control information (DCI) from the base station, the downlink control information (DCI) comprising a timing advance command (TAC) value in a modulation and coding scheme (MCS) field of the DCI; as well as The TAC value is used to calculate a closed loop component of the second TA value.

7. The method according to claim 1, wherein in order to determine the second TA value according to the second TA mode, the method further comprises: receiving downlink control information (DCI) from the base station, the downlink control information (DCI) including a TA drift rate of a TA drift, a high-order derivative of the TA drift, and an epoch time; as well as A closed-loop component of the second TA value is calculated using the TA drift rate, the high-order derivatives of the TA drift, and the epoch time. The method of claim 1 , wherein the GNSS data acquisition failure comprises a loss of GNSS signals at the UE. 9 . The method of claim 1 , wherein the GNSS data acquisition failure comprises determining at the UE that a received GNSS signal does not meet GNSS signal requirements.

10. The method of claim 1, wherein the first request is transmitted further in response to determining that a remaining portion of a GNSS data validity duration of the first GNSS data at the UE does not satisfy a threshold.

11. The method of claim 10, wherein the threshold value depends on one or more of the following: a round trip time (RTT) between the UE and the base station; a distance between the UE and an NTN carrier for an NTN service link used by the UE to communicate with the base station; and The timing drift rate at the UE.

12. The method of claim 1, wherein the first request comprises one or more of: an expiry time of a GNSS data validity duration of the first GNSS data; the last GNSS measured position of the UE; and A desired minimum duration for operating in the second TA mode.

13. The method of claim 1, wherein the first reply comprises one or more of: timing for transitioning from the first TA mode to the second TA mode; Timing Advance Command (TAC) value; and A maximum duration for operating in the second TA mode.

14. The method according to claim 1, further comprising: after entering the second TA mode, identifying successful GNSS data acquisition of second GNSS data at the UE; transmitting, in response to the successful GNSS data acquisition of the second GNSS data, to a base station a second request to transition from operating in the second TA mode to operating in the first TA mode, the UE determining a third TA value for the UE using the second GNSS data according to the first TA mode; receiving a second reply from the base station, the second reply indicating that the UE can transition from operating in the second TA mode to operating in the first TA mode; as well as In response to the second reply, transition is made from operating in the second TA mode to operating in the first TA mode. The method of claim 14 , wherein the second request includes a GNSS data validity duration of the second GNSS data. 16 . The method of claim 14 , wherein the second reply includes timing for transitioning from the second TA mode to the first TA mode.

17. The method of claim 1, wherein the first TA mode is an open-loop and closed-loop TA mode. The method of claim 1 , wherein the second TA mode is a closed-loop TA mode.

19. A method for a base station of a non-terrestrial network (NTN), the method comprising: receiving, from a user equipment (UE), a first request to transition from operating in a first timing advance (TA) mode to operating in a second TA mode, the UE determining a first TA value for the UE using first global navigation satellite system (GNSS) data determined at the UE according to the first TA mode, the UE determining a second TA value for the UE according to the second TA mode without using any GNSS data; transmitting a first reply to the UE, the first reply indicating that the UE is capable of transitioning from operating in the first TA mode to operating in the second TA mode; as well as An uplink (UL) transmission is received from the UE after transmitting the first reply.

20. The method of claim 19, further comprising transmitting a medium access control element (MAC-CE) to the UE, the medium access control element (MAC-CE) comprising a TA drift rate of the TA drift, a high order derivative of the TA drift, and an epoch time.

21. The method of claim 19, further comprising transmitting a medium access control element (MAC-CE) having a timing advance command (TAC) field greater than six bits to the UE.

22. The method of claim 19, further comprising transmitting a medium access control element (MAC-CE) including a timing advance command (TAC) value to the UE, the timing advance command (TAC) value being configured as a closed-loop component for calculating the second TA value at the UE using the following equation: N TA-新 =N TA-旧 +(T A -31)*S*16*64 / 2 μ ,in: N TA-新 is the closed-loop component of the second TA value; N TA-旧 is the previous closed-loop component of the first TA value; T A is the TAC value; S is the scaling factor; as well as μ is a subcarrier spacing (SCS) value corresponding to the SCS used for the UL transmission.

23. The method of claim 19, further comprising transmitting downlink control information (DCI) including a timing advance command (TAC) field to the UE.

24. The method of claim 19, further comprising transmitting downlink control information (DCI) to the UE, the downlink control information (DCI) comprising a timing advance command (TAC) value in a modulation and coding scheme (MCS) field of the DCI.

25. The method of claim 19, transmitting downlink control information (DCI) to the UE, the downlink control information (DCI) including a TA drift rate of a TA drift, a high order derivative of the TA drift, and an epoch time.

26. The method of claim 19, wherein the first request comprises one or more of: an expiry time of a GNSS data validity duration of the first GNSS data; the last GNSS measured position of the UE; and A desired minimum duration for operating in the second TA mode.

27. The method of claim 19, wherein the first reply comprises one or more of: timing for transitioning from the first TA mode to the second TA mode; Timing Advance Command (TAC) value; and A maximum duration for operating in the second TA mode.

28. The method of claim 19, further comprising: receiving, from the UE, a second request to transition from operating in the second TA mode to operating in the first TA mode, the UE determining a third TA value for the UE using second GNSS data in accordance with the first TA mode; as well as A second reply is transmitted to the UE, the second reply indicating that the UE can transition from operating in the second TA mode to operating in the first TA mode.

29. The method of claim 28, wherein the second request includes a GNSS data validity duration of the second GNSS data.

30. A method of a user equipment (UE) of a non-terrestrial network (NTN), the method comprising: Determining to implement a power saving mode at the UE; in response to determining that the power save mode is implemented at the UE, transmitting to a base station of the NTN network a first request to transition from operating in a first timing advance (TA) mode to operating in a second TA mode, the UE determining a first TA value for the UE using first global navigation satellite system (GNSS) data determined at the UE according to the first TA mode, the UE determining a second TA value for the UE according to the second TA mode without using any GNSS data; as well as receiving a first reply from the base station, the first reply indicating that the UE can transition from operating in the first TA mode to operating in the second TA mode; in response to the reply, transitioning from operating in the first TA mode to operating in the second TA mode; determining timing of uplink (UL) transmissions using the second TA value; as well as The UL transmission is transmitted to the base station according to the timing.

31. An apparatus comprising means for performing the method according to any one of claims 1 to 30.

32. A computer-readable medium comprising instructions, which, when executed by one or more processors of an electronic device, cause the electronic device to perform the method according to any one of claims 1 to 30.

33. An apparatus comprising logic components, modules or circuits for performing the method according to any one of claims 1 to 30.

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