Uplink transmission in non-terrestrial wireless networks (NTN)

Abstract

A mechanism is provided for a user equipment (UE) to determine a transmit frequency or time advance for an uplink transmission from the UE to a base station in a non-terrestrial wireless network (NTN) without Global Navigation Satellite System (GNSS) information being available to the UE. A communication connection between the UE and the base station may be established. The UE may determine that the GNSS information is not available and may report to the base station that the GNSS information is not available. The UE may receive an indication of one or more parameters for an uplink transmission from the UE from the base station to synchronize the uplink transmission. The UE may determine a next transmit frequency based on a current transmit frequency and the received indication of the one or more parameters, and transmit the uplink transmission at the determined next transmit frequency.

Description

[Technical field]

[0001] The described aspects generally relate to non-terrestrial wireless networks (NTNs), including synchronization of uplink transmissions from user equipment (UE) in NTNs. [Background technology]

[0002] The wireless communication system may include a fifth generation (5G) system, a new radio (NR) system, a long-term evolution (LTE) system, a combination thereof, or some other wireless system. In addition, the wireless communication system may support a wide range of use cases, such as enhanced mobile broadband (eMBB), massive machine type communications (mMTC), ultra-reliable and low-latency communications (URLLC), enhanced vehicle to anything communications (eV2X), among others. Enabling support for non-terrestrial networks has been one direction of exploration in the 3rd Generation Partnership Project (3GPP). Summary of the Invention

[0003] Some aspects of the present disclosure relate to an apparatus and method for a user equipment (UE) to implement a technique for determining a transmission frequency or time advance for an uplink transmission from the UE to a base station in a non-terrestrial wireless network (NTN). In an embodiment, Global Navigation Satellite System (GNSS) information is not available to the UE for synchronization of the uplink transmission. The UE determines a transmission frequency or time advance for the uplink transmission based on an indication of one or more parameters received from the base station to overcome Doppler frequency shift to the UE. The implemented technique may be applicable to many wireless systems, for example, wireless communication systems based on 3rd Generation Partnership Project (3GPP) Release 15 (Rel-15), Release 16 (Rel-16), Release 17 (Rel-17), or higher.

[0004] Some aspects of the disclosure relate to a UE. The UE may include a transceiver configured to enable wireless communication in an NTN and a processor communicatively coupled to the transceiver. The processor may establish a communication connection with a base station in the NTN. The NTN may include a satellite, and the base station communicates with the transceiver disposed on the satellite. The processor may determine that GNSS information is not available to the UE. The processor may report to the base station that the GNSS information is not available. The processor may then receive from the base station an indication of one or more parameters for an uplink transmission from the UE to synchronize the uplink transmission. The processor may further determine a next transmit frequency based on a current transmit frequency and the received indication of the one or more parameters, and transmit the uplink transmission at the determined next transmit frequency to overcome Doppler frequency shift.

[0005] According to some aspects, the UE can receive an indication of the one or more parameters in response to a trigger event detected by the base station or periodically from the base station. The indication of the one or more parameters can be included in a Medium Access Control (MAC) Control Element (CE) message, a Downlink Control Indicator (DCI) message, a Configured Grant Configuration message, a Radio Resource Control (RRC) Configuration message, or some other control message from the base station to the UE.

[0006] According to some aspects, the indication of the one or more parameters may include a frequency offset for the UE to tune from a current transmission frequency to a next transmission frequency. The frequency offset may be a relative frequency offset equal to one or more of the fundamental offsets Y. Additionally and alternatively, the frequency offset may be an absolute frequency offset equal to one or more of the fundamental offsets Y. In some embodiments, the frequency offset may be related to a frequency drift rate and a time difference between two uplink transmissions.

[0007] According to some aspects, an indication of the one or more parameters can be included in the configured grant configuration message, the indication of the one or more parameters including a frequency offset for the UE to tune from a current transmit frequency to a next transmit frequency for the multiple uplink transmissions.

[0008] According to some aspects, the indication of the one or more parameters includes a time advance for the uplink transmission, the time advance being based on a timing drift rate and a time difference between two uplink transmissions.

[0009] According to some aspects, the processor can report to a base station that the UE is a stationary UE, report a GNSS location of the UE to the base station, and stop GNSS location tracking.

[0010] According to some aspects, a method for performing wireless communication by a UE in an NTN may include establishing a communication connection with a base station in the NTN; receiving from the base station an indication of one or more parameters for an uplink transmission from the UE; determining a next transmission frequency different from the current transmission frequency based on the current transmission frequency or the received indication of the one or more parameters; and transmitting an uplink transmission at the determined next transmission frequency.

[0011] This summary of the invention is provided merely for the purpose of illustrating some aspects to provide an understanding of the subject matter described herein. Thus, the above features are merely examples and should not be construed as narrowing the scope or spirit of the subject matter in the present disclosure. Other features, aspects, and advantages of the present disclosure will become apparent from the following detailed description, figures, and claims.

[0012] The accompanying drawings, which are incorporated in and form a part of this specification, illustrate the present disclosure and, together with the description, further serve to explain the principles of the present disclosure and to enable one skilled in the art to make and use the present disclosure. [Brief description of the drawings]

[0013] [Figure 1] FIG. 1 illustrates a non-terrestrial wireless network (NTN) including a user equipment (UE) for transmitting uplink transmissions in accordance with certain aspects of the present disclosure. [Diagram 2] FIG. 2 illustrates a block diagram of a UE including a transceiver for transmitting uplink transmissions in an NTN in accordance with certain aspects of the present disclosure. [Diagram 3] FIG. 1 illustrates an example process performed by a UE to send an uplink transmission in an NTN, in accordance with certain aspects of the present disclosure. [Figure 4A] FIG. 1 illustrates an example process performed by a UE to send an uplink transmission in an NTN, in accordance with certain aspects of the present disclosure. [Figure 4B] FIG. 1 illustrates an example process performed by a UE to send an uplink transmission in an NTN, in accordance with certain aspects of the present disclosure. [Figure 4C] FIG. 1 illustrates an example process performed by a UE to send an uplink transmission in an NTN, in accordance with certain aspects of the present disclosure. [Diagram 5] FIG. 1 illustrates an example computer system that may implement some aspects or portion(s) of the disclosure provided herein.

[0014] The present disclosure is described with reference to the accompanying drawings, in which like reference numbers generally indicate identical or functionally similar elements, and in which the left-most digit(s) of a reference number generally identifies the drawing in which the reference number first appears. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] A non-terrestrial wireless network (NTN) may be referred to as a non-terrestrial network. An NTN may refer to any network that includes a non-terrestrial flying object. An NTN may include a satellite communication network, a high altitude platform system (HAPS), an air-to-ground network, a low altitude unmanned aerial vehicle (UAV, also known as a drone), or any other NTN network. Due to the relative movement of a user equipment (UE) or a satellite in an NTN, the UE may experience a Doppler frequency shift and lose synchronization with a base station.

[0016] Traditionally, for wireless communication in NTNs, actions can be taken by the UE to overcome Doppler frequency shifts based on the UE's Global Navigation Satellite System (GNSS) location. A GNSS-capable UE can calculate the relative velocity between the UE and a satellite, as well as the round trip time (RTT) between the UE and the satellite, based on its position. From the relative velocity, the UE can calculate and apply pre-compensation for Doppler frequency shifts to ensure that its service link or uplink signals are received at the desired frequency at the satellite or base station.

[0017] However, there are situations where the GNSS location of the UE is not available to the UE for various reasons, such as to save power for the UE. Without GNSS information, the UE cannot calculate and apply pre-compensation for the Doppler frequency shift by itself. Therefore, the service link Doppler frequency shift may cause the UE and the base station to lose synchronization. Therefore, it becomes a challenge to support wireless communication for the UE in the NTN without GNSS information.

[0018] Some aspects of the present disclosure provide a mechanism for a UE to determine a transmission frequency or time advance for an uplink transmission from the UE to a base station in a NTN without GNSS information available to the UE for the uplink transmission. Instead of calculating pre-compensation of the Doppler frequency shift by the UE based on the GNSS information, the base station can calculate pre-compensation of the Doppler frequency shift for the UE and transmit the Doppler frequency shift pre-compensation to the UE as a parameter of the uplink transmission. An indication of one or more parameters for the uplink transmission can be transmitted by the base station to the UE. Thus, the UE can determine a next transmission frequency different from the current transmission frequency based on the current transmission frequency or the received indication of the one or more parameters. The UE can further transmit the uplink transmission at the determined next transmission frequency such that the Doppler frequency shift can be overcome. The mechanism presented herein may be referred to as a closed-loop frequency synchronization technique for a base station to synchronize a UE uplink transmission.

[0019] 1 illustrates an NTN 100 including a UE 101 for transmitting uplink transmissions in accordance with some aspects of the present disclosure. The wireless system 100 is provided for illustrative purposes only and is not intended to limit aspects of the disclosure.

[0020] The NTN 100 may include, but is not limited to, a UE 101, a base station 103, a satellite 102, a gateway 104, and a core network 105. The UE 101 communicates with the satellite 102 via a service link 111, and the satellite 102 communicates with the gateway 104 via a feeder link 113. The service link 111 may include a downlink 112 and an uplink 114. The satellite 102 may include a network node or a transceiver for wireless communication. There may be various implementations of the NTN 100. For example, the base station 103 and the gateway 104 may be integrated into one unit instead of being separate components. The base station 103 and the core network 105 may implement functions as a normal terrestrial wireless network without satellites, and the gateway 104 may implement functions between the terrestrial wireless network and the satellite 102.

[0021] In some embodiments, the NTN 100 may have a transmission payload and the base station 103 is located on the ground. In some embodiments, the NTN 100 may have a regeneration payload when the base station 103 may be located on a satellite 102. There may be multiple satellites with on-board base stations that communicate with each other. There may be other network entities, e.g., network controllers, relay stations (not shown). The NTN may be referred to as a wireless network, a wireless communication system, or some other name known to those skilled in the art.

[0022] In some embodiments, the NTN 100 may be a non-terrestrial flying object, such as an NTN having a satellite 102. In some embodiments, the NTN 100 may include a satellite communication network including the satellite 102, a HAPS, or an air-to-ground network, or a UAV. There may be multiple satellites in the NTN 100. The satellite 102 may be a low earth orbit (LEO) satellite, a medium earth orbit (MEO) satellite, or a geostationary earth orbit (GEO) satellite. The NTN 100 may be a HAPS, which may be an aerial platform including aircraft, balloons, and airships. For example, the NTN 100 may include an international mobile communications base station known as a HIBS. The HIBS system may provide mobile services on the same transmission frequencies used by terrestrial mobile networks. The NTN 100 may be an air-to-ground network to provide in-flight connectivity to aircraft by utilizing ground stations that act similarly to base stations in terrestrial mobile networks. The NTN 100 may be a mobile-enabled low-altitude UAV.

[0023] In some embodiments, the satellite 102 may be a GEO satellite deployed at an altitude of 35786 Km and characterized by slow movement around its orbital position relative to a point on the Earth. Compared to terrestrial cellular systems, communication networks based on GEO satellites have large propagation delays and high propagation losses that must be considered in the overall design of the satellite network. Additionally and alternatively, the satellite 102 may be a LEO satellite at an altitude of 300-3000 km. As a result, the satellite 102 may have lower propagation delays, lower propagation losses, and higher Doppler frequency shifts than GEO satellites.

[0024] According to some aspects, the base station 103 may be a fixed station or a mobile station. In some embodiments, the base station 103 may be mounted on a satellite 102. The base station 103 may also be referred to by other names such as a base transceiver system (BTS), an access point (AP), a transmit / receive point (TRP), an evolved Node B (eNB), a next generation Node B (gNB), a 5G Node B (NB), or other equivalent terminology.

[0025] According to some aspects, the UE 101 may be stationary or mobile. The UE 101 may be a handheld terminal or a very small satellite earth station (VSAT) equipped with a parabolic antenna and typically mounted on a building or a vehicle. The UE 101 may be a cellular phone (e.g., a smartphone), a personal digital assistant (PDA), a wireless modem, a wireless communication device, a handheld device, a laptop, a desktop, a cordless phone, a wireless local loop station, a tablet, a camera, a gaming device, a netbook, an ultrabook, a medical device or equipment, a biosensor or device, a wearable device (smart watch, smart clothing, smart glasses, smart jewelry such as a smart wristband, a smart ring, or a smart bracelet), an entertainment device (e.g., a music or video device, or a satellite radio), a vehicle component, a smart meter, an industrial manufacturing equipment, a global positioning system device, an Internet of Things (IoT) device, a machine type communication (MTC) device, an evolved or enhanced machine type communication (eMTC) device, or any other suitable device configured to communicate over a wireless medium. For example, MTC and eMTC devices may include robots, drones, location tags, etc.

[0026] According to some aspects, the service link 111 may include a downlink 112 and an uplink 114. Due to the relative movement of the UE 101 and the satellite 102, the UE 101 may experience a Doppler frequency shift and lose synchronization with the base station 103. The Doppler frequency shift may be observed when a wave source is moving relative to an observer or vice versa. This movement generates a change in frequency with respect to an observer, the source and observer may be the satellite 102 and the UE 101, respectively. If the UE 101, which may be a moving source, emits waves with an actual frequency while the satellite 102, which may be an observer, is stationary with respect to the medium, the satellite 102 may detect waves with a frequency different from the actual frequency, the difference being caused by the Doppler frequency shift. A similar situation may be observed when the satellite 102 moves. In satellite communications, the Doppler frequency shift needs to be compensated for. A fast moving satellite may have a Doppler frequency shift of tens of kilohertz relative to a ground station. The speed, and therefore the magnitude of the Doppler frequency shift, varies with the curvature of the Earth. Dynamic Doppler compensation is used in which the frequency of the signal is gradually changed during transmission so that the satellite receives a constant frequency signal.

[0027] Typically, dynamic Doppler compensation for Doppler frequency shift is calculated based on the location, e.g., GNSS location, of the UE 101. For example, a GNSS-capable UE 101 can calculate the GNSS location 121 and the relative velocity between the UE 101 and the satellite 102, as well as the RTT between the UE 101 and the satellite 102, based on its position. From the relative velocity, the UE 101 can calculate and apply pre-compensation for the Doppler frequency shift to ensure that its service link 111 or uplink signal is received at the satellite 102 or base station 103 on the desired frequency.

[0028] However, there are situations where the GNSS location of the UE 101 is not available to the UE 101 for various reasons. In some embodiments, to save costs, the UE 101 may not have GNSS capability. In some other embodiments, the UE 101 may have GNSS capability but may decide to stop using GNSS capability to save power for the UE 101. Without GNSS information, the UE 101 cannot calculate and apply pre-compensation for Doppler frequency shifts by itself. Thus, Doppler frequency shifts in the service link 111 may cause the UE to lose synchronization with the base station.

[0029] In accordance with some aspects, instead of calculating pre-compensation for the Doppler frequency shift, the UE 101 may receive an indication 115 of one or more parameters for an uplink transmission from the UE 101 via the downlink 112. More specifically, the UE 101 may establish a communication connection with the base station 103, which may include both the downlink 112 and the uplink 114. The UE 101 may receive an indication 115 of one or more parameters for an uplink transmission from the UE 101 via the uplink 114 from the base station 103. Based on the current transmission frequency 123 or the received indication 115 of the one or more parameters, the UE 101 may determine a next transmission frequency 125 that is different from the current transmission frequency 123 to compensate for the Doppler frequency shift between the UE 101 and the satellite 102. The UE 101 may then transmit an uplink transmission at the determined next transmission frequency.

[0030] According to some aspects, the UE 101 may be implemented according to a block diagram as shown in FIG. 2. Referring to FIG. 2, the UE 101 may have an antenna panel 217 coupled to the transceiver 203 and including one or more antenna elements for forming various transmit beams, e.g., transmit beam 213, controlled by a processor 209. The transceiver 203 and the antenna panel 217 (using the transmit beam 213) may be configured to enable wireless communication in a wireless network. In particular, the transceiver 203 may include a radio frequency (RF) circuit 216, a transmit circuit 212, and a receive circuit 214. The RF circuit 216 may include multiple parallel RF chains for one or more of the transmit or receive functions, each of which is connected to one or more antenna elements of the antenna panel. In addition, the processor 209 may be communicatively coupled to the memory 201, which is further coupled to the transceiver 203. Various data may be stored in the memory 201. In some examples, the memory 201 may store an indication 115 of one or more parameters for uplink transmission from the UE 101, a current transmission frequency 123, a next transmission frequency 125, or other information.

[0031] In some embodiments, the memory 201 may include instructions that, when executed by the processor 209, perform operations described herein, such as operations to compensate for Doppler frequency shifts between the UE 101 and the satellite 102. Alternatively, the processor 209 may be "hard-coded" to perform the operations described herein.

[0032] In some embodiments, the processor 209 may be configured to establish a communication connection with the base station 103. The processor 209 may determine that the GNSS information 121 is not available to the UE. The processor 209 may report, via the transceiver 203, to the base station 103 that the GNSS information 121 is not available. The processor 209 may then receive, from the base station 103, an indication 115 of one or more parameters for an uplink transmission from the UE 101. The processor 209 may further determine a next transmission frequency 125 based on the current transmission frequency 123 or the received indication 115 of the one or more parameters, and transmit the uplink transmission at the determined next transmission frequency 125.

[0033] According to some aspects, the UE 101 can receive an indication 115 of one or more parameters periodically from the base station 103. The indication 115 having the one or more parameters can be included in a Medium Access Control (MAC) Control Element (CE) message, a Downlink Control Indicator (DCI) message, a configured grant configuration message, a Radio Resource Control (RRC) configuration message, or some other control message.

[0034] According to some aspects, the indication 115 of the one or more parameters may include an indication of a frequency offset for the UE 101 to adjust from the current transmission frequency 125 to the next transmission frequency 123. The frequency offset may be a relative frequency offset equal to one or more of the fundamental offsets Y. In other words, the frequency difference between the next transmission frequency 125 and the current transmission frequency 123 is equal to a multiple of the fundamental offset Y. Additionally and alternatively, the frequency offset may be an absolute frequency offset equal to one or more of the fundamental offsets Y. In other words, the next transmission frequency 125 is equal to a multiple of the fundamental offset Y, regardless of the current transmission frequency 123. In some embodiments, the frequency offset may be related to a frequency drift rate and a time difference between two uplink transmissions.

[0035] According to some aspects, an indication of one or more parameters 115 can be included in the configured grant configuration message, the indication of the one or more parameters including a frequency offset for the UE to tune from a current transmission frequency 123 to a next transmission frequency 125 for the multiple uplink transmissions.

[0036] According to some aspects, the indication 115 of the one or more parameters includes a time advance for the uplink transmission, the indication of the time advance being based on a timing drift rate and a time difference between two uplink transmissions.

[0037] According to some aspects, the processor 209 can report to the base station 103 that the UE 101 is a stationary UE, report the GNSS location of the UE 101 to the base station 103, and stop GNSS location tracking.

[0038] 3 illustrates an example process 300 performed by a UE to transmit an uplink transmission in an NTN in accordance with some aspects of the present disclosure. According to some aspects, as shown in FIG. 3, the process 300 may be performed by a UE 101.

[0039] At 301, the UE 101 may establish a communication connection with a base station in the NTN. For example, as shown in FIG. 1, the UE 101 may establish a communication connection with a base station 103 in the NTN 100. The communication connection may include a service link 111 and a feeder link 113, where the service link 111 may include an uplink 114 and a downlink 112, and the feeder link 113 provides a communication link between the satellite 102 and the gateway 104.

[0040] At 303, the UE 101 may receive from the base station an indication of one or more parameters for uplink transmission from the UE. For example, as shown in FIG. 1, the UE 101 may receive from the base station 103 an indication 115 of one or more parameters for uplink transmission from the UE. The UE 101 may store the indication 115.

[0041] At 305, the UE 101 may determine a next transmission frequency different from the current transmission frequency based on the current transmission frequency or the received indication of one or more parameters. For example, as shown in FIG. 1, the UE 101 may determine a next transmission frequency 125 different from the current transmission frequency based on the current transmission frequency 123 or the received indication 115 of one or more parameters. The frequency difference between the current transmission frequency 123 and the next transmission frequency 125 is to compensate for the Doppler frequency shift to the UE 101. The frequency difference between the current transmission frequency 123 and the next transmission frequency 125 may be determined based on the received indication 115 of one or more parameters from the base station 103 instead of being calculated by the UE 101 based on the GNSS information.

[0042] At 307, the UE 101 may transmit an uplink transmission on the determined next transmit frequency. For example, as shown in FIG. 1, the UE 101 may transmit an uplink transmission on the determined next transmit frequency 125.

[0043] 4A-4C illustrate example processes performed by a UE to send an uplink transmission in an NTN in accordance with certain aspects of the disclosure, such as process 400, process 410, and process 420. Process 400, process 410, and process 420 may be examples of process 300 shown with more, less, or different details.

[0044] A process 400 is shown in FIG. 4A, in which an indication of one or more parameters for an uplink transmission is carried in a medium access control (MAC) control element (CE) message.

[0045] In 401, the UE 101 may establish a communication connection with the base station 103. The communication connection may include a service link 111 and a feeder link 113, and the service link 111 may include an uplink 114 and a downlink 112. The operations performed in 401 may be examples of the operations performed in 301.

[0046] At 402, the UE 101 may determine that GNSS information is not available to the UE 101 and report the GNSS information is not available to the base station 103. The UE 101 may switch from open-loop frequency adjustment based on the downlink receive frequency to closed-loop frequency adjustment based on explicit control from the base station 103. Thus, the UE 101 may decouple the downlink receive frequency in the downlink 112 from the uplink transmit frequency in the uplink 114.

[0047] At 403, based on the report to the base station 103, the UE 101 can receive an indication 115 of one or more parameters, which can be carried by a MAC CE message and can include a time advance or a frequency offset update for both time and frequency synchronization purposes. The operations performed at 403 can be examples of the operations performed at 303. In some embodiments, the indication 115 can include both a frequency offset update and a time advance. In general, a UE 101 without GNSS can lose both frequency and time synchronization. Thus, when the indication 115 includes both a frequency offset update and a time advance, it can help correct both time and frequency errors in the UE 101 due to Doppler frequency shift and loss of time synchronization. The indication 115 can be transmitted periodically with a fixed period or can be event triggered. For example, the base station 103 can transmit the indication 115 when the base station 103 detects that the reception from the UE 101 is below a performance threshold.

[0048] At 405, the UE 101 may apply the frequency offset update indicated by the MAC CE message and determine a next transmission frequency 125 different from the current transmission frequency 123 based on the current transmission frequency 123 or the received indication 115. In some embodiments, the UE 101 may apply the frequency offset indicated in the MAC CE message X ms, e.g., 3 ms, after receiving the MAC CE message. The operations performed at 405 may be examples of the operations performed at 305.

[0049] In some embodiments, the frequency offset update included in the indication 115 and carried by the MAC CE message may be a relative frequency offset with a frequency correction range of + / -X Hz. In some embodiments, a string of A bits may be used to indicate the relative frequency offset. Acan be derived from the A bit sequence as a natural representation. For example, the instruction "00101" is F, which is an instruction to adjust the transmission frequency. A = 5. In some embodiments, A may be less than 8 bits to fit into the byte with the frequency offset group identifier. In some embodiments, the frequency offset may be equal to one or more of the fundamental offsets Y Hz. In particular, F new The next frequency, 125, is denoted as F new =F old +(F A -Z)*Y, where F old is the current frequency 123, Z=2 A-1 -1 or Z=2 A-1 Furthermore, or alternatively, F new F new =F old +(F A -Z)*Y*2 μ It can be calculated as Z=2 A-1 -1 or Z=2 A-1 The base offset Y may depend on the subcarrier spacing. If the subcarrier spacing is large, the value of Y may be large, and if the subcarrier spacing is small, the value of Y may be small. For example, Y may be a certain percentage of the subcarrier spacing. In addition, Y may depend on the satellite deployment scenario. If the satellite 102 is a GEO, Y may have a smaller value, but if the satellite 102 is a LEO, Y may have a larger value.

[0050] In some embodiments, the frequency offset update included in the indication 115 and carried by the MAC CE message may be an absolute frequency offset. Assuming that a string of A bits in total is used for the absolute frequency offset, F A can be derived from the A bit sequence as a natural representation. The next transmission frequency F new F new =F A *Y. Additionally and alternatively, the following transmission frequency F new F new=F A *Y*2 μ The basic offset Y may depend on the subcarrier spacing. If the subcarrier spacing is large, the value of Y may be large, and if the subcarrier spacing is small, the value of Y may be small. For example, Y may be a certain percentage of the subcarrier spacing. In addition, Y may depend on the satellite deployment scenario. If the satellite 102 is a GEO, Y may have a smaller value, but if the satellite 102 is a LEO, Y may have a larger value.

[0051] In some embodiments, instead of using a MAC CE message, a downlink control indicator (DCI) message may be used to carry an indication 115 of one or more parameters for uplink transmission from the UE 101. The DCI message for carrying the indication 115 may be suitable for UEs without GNSS capability. If the UE does not always receive the GNSS signal, the UE may report to the base station 103 so that a corresponding time and frequency correction indication may be sent from the base station 103. The UE may switch from an open-loop frequency adjustment based on the downlink receive frequency to a closed-loop frequency adjustment based on an explicit control from the base station 103. The UE 101 may decouple the uplink transmit frequency from the downlink receive frequency. When the UE 101 receives a DCI message with a frequency offset update, the UE 101 applies the frequency offset update on the uplink frequency used in the last uplink transmission, which is the current transmit frequency 123. For the frequency offset update, certain timeline restrictions may be applied.

[0052] The DCI message may be a non-fallback DCI, such as DCI format 0_1 ​​or 0_2. An uplink grant DCI with frequency offset information may be used to adjust the frequency of a PUSCH transmission. A downlink grant DCI with frequency offset information may be used to adjust the frequency of a PUCCH transmission. In some embodiments, the DCI message may have a configurable field to include a frequency offset indication. The DCI message including the frequency offset indication may differ from the legacy DCI format. For example, the DCI message including the frequency offset indication may be based on scrambling of the DCI cyclic redundancy check (CRC), and a new radio network temporary identifier (RNTI) may be used to scramble the CRC of the DCI with the frequency offset indication.

[0053] In some embodiments, a configurable table may be used to indicate the frequency offset update value. The DCI message may have a field indicating the table entry. The relative frequency offset may be indicated as (-Δ, 0, Δ, 2Δ). new =F old +Y, where Y is indicated by the DCI message, and F old is the current transmission frequency 123 used in the previous uplink transmission.

[0054] In some embodiments, other control messages can be used instead of the MAC CE message or the DCI message. For example, the uplink configuration grant message after the dynamic uplink grant by DCI can be used to include the indication 115. In some embodiments, the configured grant configuration message can include the frequency offset indication 115. The configured grant configuration message can be either a type 1 or type 2 configured grant. When the configured grant configuration message is used to carry a frequency offset gap, the frequency offset gap can be applicable to each period of the configured grant "frequency offset step" field. A frequency offset gap Δ can be applied to each uplink transmission in the configured grant. For example, the first uplink transmission can be based on a transmission frequency f, then the second uplink transmission can be based on f+Δ, the third uplink transmission based on f+2Δ, etc. In the case of a type 2 configured grant, the "frequency offset step" can be indicated in the activation DCI including this field.

[0055] 4B, in which an indication of one or more parameters for uplink transmission is sent to a stationary UE. The stationary UE may report its GNSS location to the base station and rely on the base station to control time and frequency synchronization in the RRC connected mode.

[0056] In 411, the UE 101 may establish a communication connection with the base station 103, where the UE 101 is stationary. The operations performed in 401 may be examples of the operations performed in 301.

[0057] At 412, the UE 101 can determine and report its GNSS information, such as GNSS location, to the base station 103. A stationary UE may report its GNSS location in an initial phase (initial access). The GNSS location may be configured when the device is first installed or activated. The UE 101 can report to the base station 103 that it is a stationary UE so that the base station 103 has full control of the uplink time and frequency synchronization for the UE 101.

[0058] At 413, based on the report to the base station 103, the UE 101 can switch from an open-loop frequency adjustment based on the downlink receive frequency to a closed-loop frequency adjustment based on an explicit control from the base station 103. A stationary UE does not need to track its GNSS location and does not need to read serving satellite ephemeris information. Thus, the UE 101 can stop GNSS location tracking, which can save power by avoiding reading system information with serving satellite ephemeris. Thus, the UE 101 can decouple the uplink transmit frequency in the uplink 114 from the downlink receive frequency in the downlink 112.

[0059] In some embodiments, the UE 101 can receive an indication 115 of one or more parameters, apply the indication 115, such as a frequency offset update indicated by a MAC CE message, and determine a next transmission frequency 125 that is different from the current transmission frequency 123 based on the current transmission frequency 123 or the received indication 115.

[0060] In some embodiments, the frequency offset is determined by the frequency drift rate (D f ) and the time difference between two uplink transmissions. fmay be indicated by the base station 103 to the UE 101 to account for the Doppler frequency shift on the service link 111 due to satellite motion. The frequency offset may also be indicated by the base station 103, which may be included in the MAC CE message, the RRC configuration of the DCI message. The next transmission frequency is F new =F old +D f Δ t where Δ t Δ can be the time difference between two uplink transmissions. t can be tracked by a timer, and the validity of the timer relative to the frequency drift rate can be configured or signaled by the base station 103.

[0061] 4C, in which the indication of one or more parameters for uplink transmission from the UE can include a timing advance. The indication can be carried by a MAC CE message or other control message.

[0062] At 421, the UE 101 may establish a communication connection with the base station 103. The communication connection may include a service link 111 and a feeder link 113, where the service link 111 may include an uplink 114 and a downlink 112. The operations performed at 421 may be examples of the operations performed at 301.

[0063] At 422, the UE 101 may determine that the GNSS information is not available to the UE 101 and may report the GNSS information is not available to the base station 103. The UE 101 may switch from open-loop time adjustment to closed-loop time adjustment based on explicit control from the base station 103.

[0064] At 423, based on the report to the base station 103, the UE 101 may receive an indication 115 of one or more parameters, which may be carried by a MAC CE message and may include a time advance or a frequency offset update for frequency synchronization purposes. In some embodiments, the indication 115 may include both a frequency offset update and a time advance, such as a timing advance drift rate indication.

[0065] At 425, the UE 101 may apply the time advance and / or frequency offset update indicated by the MAC CE message and determine the next transmit frequency 125 based on the current transmit frequency 123 or the received indication 115. The operations performed at 425 may be examples of the operations performed at 305.

[0066] In some embodiments, the timing advance drift rate indication may be carried by a MAC CE message. If the UE 101 is in a connected mode and does not receive GNSS information for some time, the UE 101 may report to the base station 103 that the GNSS information is not available. The base station 103 may trigger the timing advance drift rate to be carried by the MAC CE message. In some embodiments, the MAC CE message may include the TA drift rate (D TA ) In some other embodiments, the MAC CE message can carry only TA(N TA ) and TA drift rate (D TA ) may convey both the TA drift rate and the AT drift rate. Additionally, higher order derivatives of the TA drift rate may also be included. The base station 103 may further set and signal a validity timer for Δt. The UE 101 may maintain the TA based on the following formula: T TA =(N TA +N TA,UE-specifc +N TA,common +N TA,offset )×T C Here, NTA,new =N TA,old +D TA *Δt.

[0067] Various aspects may be implemented using one or more computer systems, such as computer system 500 shown in FIG. 5. Computer system 500 may be any computer capable of performing the functions described herein, such as UE 101 or base station 103 shown in FIG. 1 and FIG. 2 for the operations described for processor 209 or process 300, process 400, process 410, or process 420 shown in FIG. 3, FIG. 4A-4C. Computer system 500 includes one or more processors (also referred to as central processing units or CPUs), such as processor 504. Processor 504 is connected (e.g., by a bus) to a communication infrastructure 506. Computer system 500 also includes user input / output device(s) 503, such as a monitor, keyboard, pointing device, etc., that communicate with communication infrastructure 506 via user input / output interface(s) 502. Computer system 500 also includes a main or primary memory 508, such as a random access memory (RAM). Main memory 508 may include one or more levels of cache. Main memory 508 stores control logic (eg, computer software) and / or data.

[0068] Computer system 500 may also include one or more secondary storage devices or memories 510. Secondary memory 510 may include, for example, a hard disk drive 512 and / or a removable storage device or drive 514. Removable storage drive 514 may be a floppy disk drive, a magnetic tape drive, a compact disk drive, an optical storage device, a tape backup device, and / or any other storage device / drive.

[0069] The removable storage drive 514 can interact with a removable storage unit 518. The removable storage unit 518 includes a computer usable or computer readable storage device having computer software (control logic) and / or data stored thereon. The removable storage unit 518 may be a floppy disk, magnetic tape, compact disk, DVD, optical storage disk, and / or any other computer data storage device. The removable storage drive 514 reads from and / or writes to the removable storage unit 518 in a well-known manner.

[0070] According to some aspects, secondary memory 510 may include other means, instrumentalities, or other techniques for making computer programs and / or other instructions and / or data accessible by computer system 500. Such means, media, or other techniques may include, for example, removable storage unit 522 and interface 520. Examples of removable storage unit 522 and interface 520 may include program cartridges and cartridge interfaces (such as those found in video game devices), removable memory chips (such as EPROMs or PROMs) and associated sockets, memory sticks and USB ports, memory cards and associated memory card slots, and / or any other removable storage unit and associated interface.

[0071] In some examples, main memory 508, removable storage unit 518, removable storage unit 522 may store instructions that, when executed by processor 504, cause processor 504 to perform operations for a UE or a base station, such as UE 101 or base station 103 shown in Figures 1 and 2. In some examples, the operations include operations shown and described with respect to process 300, process 400, process 410, or process 420 as shown in Figures 3, 4A-4C.

[0072] The computer system 500 may further comprise a communication or network interface 524. The communication interface 524 enables the computer system 500 to communicate and interact with any combination of remote devices, remote networks, remote entities, etc. (individually and collectively referred to by reference number 528). For example, the communication interface 524 may enable the computer system 500 to communicate with the remote devices 528 over a communication path 526, which may be wired and / or wireless and may include any combination of a LAN, a WAN, the Internet, etc. Control logic and / or data may be transmitted to and from the computer system 500 via the communication path 526. The operations of the communication interface 524 may be performed by a wireless controller and / or a cellular controller. The cellular controller may be a separate controller for managing communications according to different wireless communication technologies. The operations in the aforementioned aspects may be implemented in a wide variety of configurations and architectures. Thus, some or all of the operations in the aforementioned aspects may be performed in hardware, software, or both. In some aspects, a tangible non-transitory apparatus or article of manufacture is also referred to herein as a computer program product or program storage device that includes a tangible non-transitory computer usable or readable medium having control logic (software) stored thereon. This includes, but is not limited to, computer system 500, main memory 508, secondary memory 510, removable storage units 518 and 522, and tangible articles of manufacture embodying any combination of the foregoing. Such control logic, when executed by one or more data processing devices (such as computer system 500), causes such data processing devices to operate as described herein.

[0073] Based on the teachings contained herein, it will be apparent to one skilled in the relevant art(s) how to make and use aspects of the present disclosure using data processing devices, computer systems and / or computer architectures other than those shown in Figure 5. In particular, aspects may operate with software, hardware, and / or operating system implementations other than those described herein.

[0074] It is understood that it is the "Description of Embodiments" section, and not the "Summary" and "Abstract" sections, that are intended to be used to interpret the claims. The Summary and Abstract sections may describe one or more exemplary aspects of the disclosure, but not all of the exemplary aspects of the disclosure, as contemplated by the inventor(s), and thus are not intended to limit the scope of the disclosure or the appended claims in any way.

[0075] Although the present disclosure is described herein with reference to exemplary embodiments for exemplary fields and applications, it should be understood that the present disclosure is not limited to the exemplary embodiments. Other embodiments and variations of the embodiments are possible and are within the scope and spirit of the present disclosure. By way of example and without limiting the generality of this paragraph, the embodiments are not limited to the software, hardware, firmware, and / or entities shown in the figures and / or described herein. Moreover, the embodiments (whether or not explicitly described herein) have significant utility for fields and applications beyond the examples described herein.

[0076] Aspects have been described herein with the help of functional building blocks illustrating implementations of certain functions and relationships thereof. Boundaries of these functional building blocks have been arbitrarily defined herein for convenience of description. Alternative boundaries may be defined so long as the specified functions and relationships (or their equivalents) are appropriately performed. In addition, alternative aspects may perform functional blocks, steps, operations, methods, etc. using orders different from those described herein.

[0077] References herein to "one embodiment," "one embodiment," "exemplary embodiment," or similar phrases indicate that the described embodiment may include a particular feature, structure, or characteristic, but not all embodiments may necessarily include the particular feature, structure, or characteristic. Moreover, such phrases do not necessarily refer to the same embodiment. Furthermore, when a particular feature, structure, or characteristic is described in connection with one embodiment, it is within the knowledge of one of ordinary skill in the relevant art(s) to incorporate such particular feature, structure, or characteristic in other aspects, whether or not expressly mentioned or described herein.

[0078] The breadth and scope of the present disclosure should not be limited by any of the above-described exemplary aspects, but should be defined only in accordance with the following claims and their equivalents.

[0079] In one or more embodiments, for example, at least one of the components depicted in one or more of the preceding figures may be configured to perform one or more of the operations, techniques, processes, and / or methods as described in the Examples section below. For example, circuitry associated with a sled device, router, network element, etc. described above in connection with one or more of the preceding figures may be configured to operate according to one or more of the examples described in the Examples section below.

[0080] This disclosure contemplates that entities involved in the collection, analysis, disclosure, transmission, storage, or other use of such personal information data will adhere to robust privacy policies and / or privacy practices. Specifically, such entities should implement and consistently use privacy policies and practices that are generally recognized as meeting or exceeding industry or government requirements for keeping personal information data confidential and secure. Such policies should be easily accessible by users and should be updated as data collection and / or use changes. Personal information from users should be collected for the entity's lawful and legitimate uses and should not be shared or sold except for those lawful uses. Furthermore, such collection / sharing should only be carried out after the user is informed and consented to. Moreover, such entities should consider taking all necessary measures to protect and secure access to such personal information data and ensure that others who have access to the personal information data adhere to their privacy policies and procedures. Furthermore, such entities may subject themselves to third-party assessments to attest to their adherence to widely accepted privacy policies and practices. Moreover, policies and practices should be adapted to the specific types of personal information data collected and / or accessed, and should conform to applicable laws and standards, including jurisdiction-specific considerations. For example, in the United States, collection or access of certain health data may be governed by federal and / or state laws, such as the Health Insurance Portability and Accountability Act (HIPAA), while health data in other countries may be subject to other regulations and policies and should be addressed accordingly. Therefore, different privacy practices should be maintained with respect to different types of personal data in each country.

Claims

1. 1. A method for performing wireless communication with a user equipment (UE), comprising: Establishing a communication connection with a base station in a non-terrestrial wireless network (NTN); determining whether Global Navigation Satellite System (GNSS) information is unavailable to the UE; in response to determining that the GNSS information is unavailable, reporting to the base station that the GNSS information is unavailable; and receiving from the base station an indication of one or more parameters for uplink transmission from the UE based on the report to the base station; determining a next transmission frequency that is different from the current transmission frequency based on a current transmission frequency and the received indication of the one or more parameters; transmitting the uplink transmission on the determined next transmission frequency; and A method comprising:

2. reporting to the base station that the UE is a stationary UE; reporting a Global Navigation Satellite System (GNSS) location of the UE to the base station during an initial access phase configured when the UE is first installed; stopping the GNSS location tracking; and The method of claim 1 further comprising:

3. The method of claim 1 , wherein the UE periodically receives the indication of the one or more parameters from the base station.

4. 2. The method of claim 1, wherein the indication of the one or more parameters is included in a Medium Access Control (MAC) Control Element (CE) message, a Downlink Control Indicator (DCI) message, a configured grant configuration message, or a Radio Resource Control (RRC) configuration message.

5. The method of claim 1 , wherein the indication of the one or more parameters includes a frequency offset for the UE to tune from the current transmission frequency to the next transmission frequency.

6. The method of claim 5 , wherein the frequency offset between the current transmission frequency and the next transmission frequency is a relative frequency offset equal to one or more of a fundamental offset Y.

7. The method of claim 5 , wherein the frequency offset is an absolute frequency offset equal to one or more of a fundamental offset Y.

8. The method of claim 5 , wherein the frequency offset is related to a frequency drift rate and a time difference between two uplink transmissions.

9. 2. The method of claim 1 , wherein the indication of the one or more parameters is included in a configured grant configuration message, and the indication of the one or more parameters includes a frequency offset for the UE to tune from the current transmission frequency to the next transmission frequency for multiple uplink transmissions.

10. 2. The method of claim 1, wherein the indication of the one or more parameters includes a time advance for the uplink transmission, the time advance being based on a timing drift rate and a time difference between two uplink transmissions.

11. The method of claim 1 , wherein the non-terrestrial wireless network includes a satellite, and the base station is in communication with a transceiver located on the satellite.

12. a transceiver configured to enable wireless communication in a non-terrestrial wireless network (NTN); a processor communicatively coupled to the transceiver, the processor comprising: Establishing a communication connection with a base station in the NTN; determining whether Global Navigation Satellite System (GNSS) information is unavailable to the UE; in response to determining that the GNSS information is unavailable, reporting to the base station that the GNSS information is unavailable; receiving from the base station an indication of one or more parameters for uplink transmission from the UE based on the report to the base station; determining a next transmission frequency based on a current transmission frequency and the received indication of the one or more parameters; A user equipment (UE) configured to transmit the uplink transmission on the determined next transmission frequency.

13. The processor, Reporting to the base station that the UE is a stationary UE; reporting a Global Navigation Satellite System (GNSS) location of the UE to the base station during an initial access phase configured when the UE is first installed; The UE of claim 12 , further configured to stop the GNSS location tracking.

14. The UE of claim 12 , wherein the UE periodically receives the indication of the one or more parameters from the base station.

15. 13. The UE of claim 12, wherein the indication of the one or more parameters is included in a Medium Access Control (MAC) Control Element (CE) message, a Downlink Control Indicator (DCI) message, a configured grant configuration message, or a Radio Resource Control (RRC) configuration message.

16. The UE of claim 12 , wherein the indication of the one or more parameters includes a frequency offset for the UE to tune from the current transmission frequency to the next transmission frequency.

17. 17. The UE of claim 16, wherein the frequency offset between the current transmission frequency and the next transmission frequency is a relative frequency offset equal to one or more of a fundamental offset Y.

18. 13. The UE of claim 12, wherein the indication of the one or more parameters includes a time advance for the uplink transmission, the time advance being based on a timing drift rate and a time difference between two uplink transmissions.

19. A non-transitory computer-readable medium storing instructions that, when executed by a processor of a user equipment (UE), cause the UE to perform operations, the operations including: Establishing a communication connection with a base station in a non-terrestrial wireless network (NTN); determining that Global Navigation Satellite System (GNSS) information is not available to the UE; reporting to the base station that the GNSS information is unavailable; and receiving from the base station an indication of one or more parameters for uplink transmission from the UE based on the report to the base station; determining a next transmission frequency based on a current transmission frequency and the received indication of the one or more parameters; transmitting the uplink transmission on the determined next transmission frequency; and A non-transitory computer readable medium comprising:

20. 20. The non-transitory computer-readable medium of claim 19, wherein the indication of the one or more parameters is included in a Medium Access Control (MAC) Control Element (CE) message, a Downlink Control Indicator (DCI) message, a configured grant configuration message, or a Radio Resource Control (RRC) configuration message.

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