Compensation of uplink timing error for non-terrestrial networks

Abstract

A method for wireless communication by a user equipment (UE) includes modulating a symbol stream onto at least one subcarrier to generate an uplink signal in the frequency domain for transmission to a receiver in a non-terrestrial network. The method further includes applying the phase rotation amount to at least one subcarrier in the frequency domain. The method further includes transforming the uplink signal from the frequency domain to a time domain uplink signal. The method includes transmitting the time domain uplink signal to the receiver after applying the phase rotation to the at least one subcarrier.

Description

[0001] Cross - Reference to Related Applications

[0002] This application claims priority to U.S. Patent Application No. 18 / 074,308, filed on December 2, 2022, entitled "COMPENSATION OF UPLINK TIMING ERRORS FOR NON - TERRESTRIAL NETWORKS", the entire disclosure of which is hereby incorporated by reference in its entirety. Technical Field

[0003] Aspects of the present disclosure generally relate to the proactive compensation of uplink timing errors in non - terrestrial networks (NTN). Background Art

[0004] Wireless communication systems are widely deployed to provide various telecommunication services such as telephony, video, data, messaging, and broadcasting. A typical wireless communication system may employ a multiple access technology that can support communication with multiple users by sharing available system resources (e.g., bandwidth, transmit power, etc.). Examples of such multiple access technologies include code - division multiple access (CDMA) systems, time - division multiple access (TDMA) systems, frequency - division multiple access (FDMA) systems, orthogonal frequency - division multiple access (OFDMA) systems, single - carrier frequency - division multiple access (SC - FDMA) systems, time - division synchronous code - division multiple access (TD - SCDMA) systems, and long - term evolution (LTE). LTE / Advanced LTE is an enhanced set of mobile standards for the universal mobile telecommunications system (UMTS) released by the 3rd Generation Partnership Project (3GPP).

[0005] A wireless communication network may include multiple base stations (BSs) that can support the communication of multiple user equipments (UEs). A user equipment (UE) may communicate with a base station (BS) via a downlink and an uplink. The downlink (or forward link) refers to the communication link from the BS to the UE, and the uplink (or reverse link) refers to the communication link from the UE to the BS. As will be described in more detail, a BS may be referred to as a Node B, gNB, access point (AP), radio head, transmit - receive point (TRP), new radio (NR) BS, 5G Node B, and so on.

[0006] The above multiple access technologies have been adopted in various telecommunication standards to provide a common protocol that enables different user equipments to communicate at the urban, national, regional, and even global levels. New Radio (NR) (which may also be referred to as 5G) is an enhanced set of the LTE mobile standard released by the 3rd Generation Partnership Project (3GPP). NR is designed to better integrate with other open standards by improving spectral efficiency, reducing costs, enhancing services, leveraging new spectrums, and using Orthogonal Frequency Division Multiplexing (OFDM) with Cyclic Prefix (CP) (CP-OFDM) on the Downlink (DL), and CP-OFDM and / or SC-FDM (e.g., also referred to as Discrete Fourier Transform Spread OFDM (DFT-s-OFDM)) on the Uplink (UL), as well as supporting beamforming, Multiple-Input Multiple-Output (MIMO) antenna technology, and carrier aggregation, so as to better support mobile broadband Internet access. Summary of the Invention

[0007] In aspects of the present disclosure, a method for wireless communication by a User Equipment (UE) includes modulating a symbol stream onto at least one subcarrier to generate an uplink signal in the frequency domain for transmission to a receiver in a non-terrestrial network. The method further includes applying a phase rotation amount to at least one subcarrier in the frequency domain. The method further includes transforming the uplink signal from the frequency domain into a time-domain uplink signal. The method further includes transmitting the time-domain uplink signal to the receiver after applying the phase rotation to at least one subcarrier.

[0008] Other aspects of the present disclosure relate to an apparatus. The apparatus has a memory and one or more processors coupled to the memory. The processor is configured to modulate a symbol stream onto at least one subcarrier to generate an uplink signal in the frequency domain for transmission to a receiver in a non-terrestrial network. The processor is further configured to apply a phase rotation amount to at least one subcarrier in the frequency domain. The processor is further configured to transform the uplink signal from the frequency domain into a time-domain uplink signal. The processor is configured to transmit the time-domain uplink signal to the receiver after applying the phase rotation to at least one subcarrier.

[0009] Other aspects of the present disclosure relate to an apparatus. The apparatus includes means for modulating a symbol stream onto at least one subcarrier to generate an uplink signal in the frequency domain for transmission to a receiver in a non-terrestrial network. The apparatus further includes means for applying a phase rotation amount to at least one subcarrier in the frequency domain. The apparatus further includes means for transforming the uplink signal from the frequency domain into a time-domain uplink signal. The apparatus includes means for transmitting the time-domain uplink signal to the receiver after applying the phase rotation to at least one subcarrier.

[0010] In other aspects of the present disclosure, a non-transitory computer-readable medium having program code recorded thereon is disclosed. The program code is executed by a processor and includes program code for modulating a symbol stream onto at least one subcarrier to generate an uplink signal in the frequency domain for transmission to a receiver in a non-terrestrial network. The program code further includes program code for applying a phase rotation amount to at least one subcarrier in the frequency domain. The program code further includes program code for transforming the uplink signal from the frequency domain into a time-domain uplink signal. The program code includes program code for transmitting the time-domain uplink signal to the receiver after applying the phase rotation to the at least one subcarrier.

[0011] Aspects generally include methods, apparatuses, systems, computer program products, non-transitory computer-readable media, user equipment, base stations, wireless communication devices, and processing systems substantially as described with reference to the figures and as illustrated in the figures and the description.

[0012] The features and technical advantages of examples in accordance with the present disclosure have been outlined rather broadly above so that the detailed description that follows may be better understood. Additional features and advantages will be described. The disclosed concepts and specific examples may be readily utilized as a basis for modifying or designing other structures for carrying out the same purposes of the present disclosure. Such equivalent constructions do not depart from the scope of the appended claims. The characteristics of the disclosed concepts in both their organization and method of operation, as well as the associated advantages, will be better understood from the following description when considered in conjunction with the accompanying figures. Each of the figures provided is for the purpose of illustration and description and is not a definition of the limits of the claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] For a more detailed understanding of the features of the present disclosure, reference may be made to the aspects, some of which are illustrated in the figures. It should be noted, however, that the figures illustrate only some aspects of the present disclosure and should not be considered as limiting its scope, as the description may admit other equivalent aspects. Like reference numerals in different figures may identify the same or similar elements.

[0014] Figure 1 is a block diagram conceptually illustrating an example of a wireless communication network in accordance with various aspects of the present disclosure.

[0015] Figure 2 is a block diagram conceptually illustrating an example of communication between a base station and a user equipment (UE) in a wireless communication network in accordance with various aspects of the present disclosure.

[0016] Figure 3 is a block diagram illustrating an example decomposed base station architecture in accordance with various aspects of the present disclosure.

[0017] Figure 4 is a block diagram illustrating an example of a wireless communication network that supports compensation for timing errors in a non-terrestrial network (NTN) in accordance with various aspects of the present disclosure.

[0018] Figure 5 is a block diagram illustrating an example of another wireless communication network that supports compensation for timing errors in a non-terrestrial network (NTN) in accordance with various aspects of the present disclosure.

[0019] Figure 6 is a block diagram illustrating phase compensation for a single subcarrier in accordance with various aspects of the present disclosure.

[0020] Figure 7 is a block diagram illustrating phase compensation for multiple subcarriers in accordance with various aspects of the present disclosure.

[0021] Figure 8 is a flowchart illustrating an example phase compensation process performed, for example, by a user equipment (UE) in accordance with various aspects of the present disclosure. Detailed Description

[0022] The various aspects of the present disclosure are described more fully hereinafter with reference to the accompanying drawings. However, the present disclosure may be embodied in many different forms and should not be construed as limited to any specific structure or function presented throughout this disclosure. Rather, these aspects are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the present disclosure to those skilled in the art. Based on this teaching, those skilled in the art should appreciate that the scope of the present disclosure is intended to cover any aspect of the present disclosure, whether implemented independently of or in combination with any other aspect of the present disclosure. For example, a device may be implemented or a method may be practiced using any number of the aspects set forth. In addition, the scope of the present disclosure is intended to cover such devices or methods practiced using other structures, functionality, or structures and functionality in addition to or as a supplement to the various aspects of the present disclosure set forth. It should be understood that any aspect of the present disclosure disclosed may be embodied by one or more elements of a claim.

[0023] Certain aspects of a telecommunications system will now be presented with reference to various devices and techniques. These devices and techniques will be described in the following detailed description and illustrated in the accompanying drawings by various blocks, modules, components, circuits, steps, processes, algorithms, etc. (collectively referred to as "elements"). These elements may be implemented using hardware, software, or a combination thereof. Whether these elements are implemented as hardware or software depends upon the particular application and design constraints imposed on the overall system.

[0024] Note that while aspects may be described using terms typically associated with 5G and later wireless technologies, aspects of the present disclosure may be applied in communication systems based on other generations, such as and including 3G and / or 4G technologies.

[0025] In a non-terrestrial network (NTN), the round-trip time from a base station to a user equipment (UE) via an intermediate satellite can be quite long. Similarly, the round-trip time between a satellite-based base station and a UE can be long. The large round-trip time is due to the large distance that the electromagnetic wave traverses. Due to the movement of the satellite, the distance between the satellite and the UE changes over time. The varying round-trip time may affect the timing synchronization between the satellite and the UE, which may lead to performance degradation.

[0026] Aspects of the present disclosure relate to the active compensation of timing errors caused by satellite movement. In some examples, a subcarrier-based phase rotation is specified for each subcarrier in the frequency domain at the UE side. This compensation is UE-specific to compensate for the timing error associated with each UE. As a result of the phase shift applied to each subcarrier, after transforming from the frequency domain to the time domain, the correct timing drift of each orthogonal frequency division multiplexing (OFDM) symbol causes the entire sequence to arrive at the receiver with a very small timing synchronization error.

[0027] The timing error experienced by the UE changes over time because the satellite moves over time. Therefore, each symbol has a different residual drift. If the timing error is within a reasonable range, for example, if the timing error is less than the cyclic prefix (CP) length, the timing error is converted into a phase rotation in the frequency domain based on the index of the subcarriers assigned to the UE. Since the satellite moves relative to the UE, the amount of drift changes with respect to the previous symbol for each symbol. According to aspects of the present disclosure, each UE rotates the corresponding subcarriers in the frequency domain before transmission. The rotation of the respective subcarriers can reduce the performance loss based on timing errors in the non-terrestrial network.

[0028] Certain aspects of the subject matter described in the present disclosure may be implemented to realize one or more of the following potential advantages. In some examples, the techniques described, such as applying phase rotation to each specific subcarrier and UE, can reduce the performance degradation due to timing errors during non-terrestrial communication.

[0029] Figure 1FIG. 0 is a diagram illustrating a network 100 in which various aspects of the present disclosure may be practiced. The network 100 may be a 5G or NR network, or some other wireless network such as an LTE network. The wireless network 100 may include multiple BSs 110 (shown as BS110a, BS110b, BS110c, and BS110d) and other network entities. A BS is an entity that communicates with user equipment (UE) and may also be referred to as a base station, NR BS, Node B, gNB, 5G Node B, access point, transmit and receive point (TRP), network node, network entity, etc. A base station may be implemented as an aggregated base station, a disaggregated base station, an integrated access and backhaul (IAB) node, a relay node, a sidelink node, etc. A base station may be implemented in an aggregated or monolithic base station architecture or, alternatively, in a disaggregated base station architecture and may include one or more of a central unit (CU), a distributed unit (DU), a radio unit (RU), a near real-time (near RT) RAN intelligent controller (RIC), or a non-real-time (non RT) RIC.

[0030] Each BS may provide communication coverage for a particular geographic area. In 3GPP, depending on the context in which the term is used, the term "cell" may refer to the coverage area of a BS and / or the BS subsystem serving that coverage area.

[0031] A BS may provide communication coverage for a macro cell, a pico cell, a femto cell, and / or another type of cell. A macro cell may cover a relatively large geographic area (e.g., with a radius of several kilometers) and may allow unrestricted access by UEs having a service subscription. A pico cell may cover a relatively small geographic area and may allow unrestricted access by UEs having a service subscription. A femto cell may cover a relatively small geographic area (e.g., a home) and may allow restricted access by UEs associated with the femto cell (e.g., UEs in a closed subscriber group (CSG)). A BS for a macro cell may be referred to as a macro BS. A BS for a pico cell may be called a pico BS. A BS for a femto cell may be referred to as a femto BS or a home BS. In the Figure 1 example shown in FIG. 8, BS110a may be a macro BS for macro cell 102a, BS110b may be a pico BS for pico cell 102b, and BS110c may be a femto BS for femto cell 102c. A BS may support one or more (e.g., three) cells. The terms "eNB," "base station," "NR BS," "gNB," "TRP," "AP," "Node B," "5G NB," and "cell" may be used interchangeably.

[0032] In some aspects, the cell need not be stationary, and the geographical area of the cell can be moved according to the location of the mobile BS. In some aspects, the BSs can use any suitable transmission network and be interconnected with each other and / or interconnected to one or more other BSs or network nodes (not shown) in the wireless network 100 through various types of backhaul interfaces (such as, direct physical connections, virtual networks, etc.).

[0033] The wireless network 100 can also include relay stations. A relay station is an entity that can receive the transmission of data from an upstream station (such as, a BS or a UE) and forward the transmission of the data to a downstream station (such as, a UE or a BS). A relay station can also be a UE that can relay transmissions for other UEs. In Figure 1 the example shown, the relay station 110d can communicate with the macro BS 110a and the UE 120d to facilitate the communication between the BS 110a and the UE 120d. A relay station can also be referred to as a relay BS, a relay base station, a relay, etc.

[0034] The wireless network 100 can be a heterogeneous network including different types of BSs (such as, macro BSs, pico BSs, femto BSs, relay BSs, etc.). These different types of BSs can have different transmission power levels, different coverage areas, and different impacts on interference in the wireless network 100. For example, a macro BS can have a high transmission power level (such as, 5 watts to 40 watts), while pico BSs, femto BSs, and relay BSs can have lower transmission power levels (such as, 0.1 watt to 2 watts).

[0035] The network controller 130 can be coupled to a group of BSs and can provide coordination and control for these BSs. The network controller 130 can communicate with the BSs via the backhaul. The BSs can also communicate with each other (such as, directly or indirectly via a wireless or wired backhaul).

[0036] The network controller 130 can be an evolved packet core (EPC), which can include at least one mobility management entity (MME), at least one serving gateway (S-GW), and at least one packet data network (PDN) gateway (P-GW). The MME can be a control node that processes the signaling between the UE 120 and the EPC. All user IP packets can be transmitted through the S-GW, which itself can be connected to the P-GW. The P-GW can provide IP address allocation and other functions. The P-GW can be connected to the IP services of the network operator. The operator's IP services can include the Internet, intranets, IP multimedia subsystem (IMS), and packet-switched (PS) streaming media services.

[0037] The network controller 130 may provide user authentication, access authorization, tracking, IP connectivity, and other access, routing, or mobility functions. In some configurations, the various functions of each access network entity or base station 110 may be distributed across various network devices (e.g., radio heads and access network controllers), or consolidated into a single network device (e.g., base station 110).

[0038] UEs 120 (e.g., 120a, 120b, 120c) may be dispersed throughout the wireless network 100, and each UE may be stationary or mobile. A UE may also be referred to as an access terminal, terminal, mobile station, subscriber unit, station, etc. A UE may be a cellular phone (e.g., a smart phone), a personal digital assistant (PDA), a wireless modem, a wireless communication device, a handheld device, a laptop computer, a cordless phone, a wireless local loop (WLL) station, a tablet device, a camera, a gaming device, a netbook, a smartbook, a ultrabook, a medical device or equipment, a biometric sensor / device, a wearable device (smart watch, smart clothing, smart glasses, smart wristband, smart jewelry (e.g., smart ring, smart bracelet)), an entertainment device (e.g., a music or video device, or a satellite radio), a vehicle-mounted component or sensor, a smart meter / sensor, an industrial manufacturing equipment, a global positioning system device, or any other suitable device configured to communicate via a wireless medium or a wired medium.

[0039] Some UEs may be considered machine type communication (MTC) or evolved or enhanced machine type communication (eMTC) UEs. For example, MTC and eMTC UEs include robots, drones, remote devices, sensors, meters, monitors, location tags, etc., that may communicate with a base station, another device (e.g., a remote device), or some other entity. A wireless node may provide connectivity to or for a network (e.g., a wide area network such as the Internet or a cellular network) via a wired or wireless communication link. Some UEs may be considered Internet of Things (IoT) devices and / or may be implemented as narrowband IoT (NB-IoT) devices. Some UEs may be considered customer premises equipment (CPE). The UE 120 may be included within a housing that houses components of the UE 120 (such as, a processor component, a memory component, etc.).

[0040] Generally speaking, any number of wireless networks can be deployed in a given geographical area. Each wireless network can support a specific radio access technology (RAT) and can operate on one or more frequencies. RAT can also be referred to as radio technology, air interface, etc. Frequency can also be referred to as carrier, frequency channel, etc. In a given geographical area, each frequency can support a single RAT to avoid interference between wireless networks of different RATs. In some cases, an NR or 5G RAT network can be deployed.

[0041] In some aspects, two or more UEs 120 (e.g., shown as UEs 120a and 120e) can communicate directly using one or more sidelink channels (e.g., communicate with each other without using the base station 110 as an intermediate device). For example, UEs 120 can communicate using peer-to-peer (P2P) communication, device-to-device (D2D) communication, vehicle-to-everything (V2X) protocols (e.g., which can include vehicle-to-vehicle (V2V) protocols, vehicle-to-infrastructure (V2I) protocols, etc.), mesh networks, and so on. In such cases, UEs 120 can perform scheduling operations, resource selection operations, and / or other operations described elsewhere herein that are performed by the base station 110. For example, the base station 110 can configure the UEs 120 via downlink control information (DCI), radio resource control (RRC) signaling, medium access control-control element (MAC-CE), or via system information (e.g., system information block (SIB)).

[0042] UE 120 can include a non-terrestrial network (NTN) timing error compensation module 140. For simplicity, only one UE 120d is shown as including the NTN timing error compensation module 140. The NTN timing error compensation module 140 can modulate a symbol stream onto at least one subcarrier to generate an uplink signal in the frequency domain for transmission to a receiver in the non-terrestrial network. The NTN timing error compensation module 140 can also apply a phase rotation amount to at least one subcarrier in the frequency domain. The NTN timing error compensation module 140 can further transform the uplink signal from the frequency domain into a time-domain uplink signal. After applying the phase rotation to the at least one subcarrier, the NTN timing error compensation module 140 can send the time-domain uplink signal to the receiver.

[0043] As indicated above, Figure 1 is provided only as an example. Other examples may be different from the examples described with reference to Figure 1 the reference.

[0044] Figure 2 shows a block diagram of a design 200 of a base station 110 and a UE 120, and the base station and the UE can be Figure 1one base station among the base stations in and Figure 1 one UE among the UEs in Figure 1 . The base station 110 may be equipped with T antennas 234a to 234t, and the UE 120 may be equipped with R antennas 252a to 252r, where generally T≥1 and R≥1.

[0045] At the base station 110, the transmit processor 220 may receive data for one or more UEs from the data source 212, select one or more modulation and coding schemes (MCSs) for the UE at least in part based on the channel quality indicator (CQI) received from each UE, process (e.g., encode and modulate) the data for the UE at least in part based on the MCS selected for each UE, and provide data symbols for all UEs. Reducing the MCS results in lower throughput but increased transmission reliability. The transmit processor 220 may also process system information (e.g., for semi-static resource allocation information (SRPI), etc.) and control information (e.g., CQI requests, grants, upper layer signaling, etc.), and provide overhead symbols and control symbols. The transmit processor 220 may also generate reference symbols for reference signals (e.g., cell-specific reference signals (CRS)) and synchronization signals (e.g., primary synchronization signal (PSS) and secondary synchronization signal (SSS)). The transmit (TX) multiple-input multiple-output (MIMO) processor 230 may perform spatial processing (e.g., precoding) on the data symbols, control symbols, overhead symbols, and / or reference symbols when applicable, and may provide T output symbol streams to the T modulators (MOD) 232a to 232t. Each modulator 232 may process the corresponding output symbol stream (e.g., for OFDM, etc.) to obtain an output sample stream. Each modulator 232 may further process (e.g., convert to analog, amplify, filter, and up-convert) the output sample stream to obtain a downlink signal. The T downlink signals from the modulators 232a to 232t may be transmitted via the T antennas 234a to 234t, respectively. According to various aspects described in more detail below, position coding may be utilized to generate synchronization signals to convey additional information.

[0046] At the UE 120, antennas 252a through 252r may receive downlink signals from the base station 110 and / or other base stations, and may provide the received signals to demodulators (DEMOD) 254a through 254r, respectively. Each demodulator 254 may condition (e.g., filter, amplify, down-convert, and digitize) the received signal to obtain input samples. Each demodulator 254 may further process these input samples (e.g., for OFDM, etc.) to obtain the received symbols. The MIMO detector 256 may obtain the received symbols from all R demodulators 254a through 254r, perform MIMO detection on the received symbols (where applicable), and provide the detected symbols. The receive processor 258 may process (e.g., demodulate and decode) the detected symbols, provide the decoded data for the UE 120 to the data sink 260, and provide the decoded control information and system information to the controller / processor 280. The channel processor may determine the reference signal received power (RSRP), received signal strength indicator (RSSI), reference signal received quality (RSRQ), channel quality indicator (CQI), etc. In some aspects, one or more components of the UE 120 may be included in a housing.

[0047] On the uplink, at the UE 120, the transmit processor 264 may receive data from the data source 262, as well as control information (e.g., for reporting including RSRP, RSSI, RSRQ, CQI, etc.) from the controller / processor 280, and process the data and control information. The transmit processor 264 may also generate reference symbols for one or more reference signals. The symbols from the transmit processor 264 may be precoded by the TX MIMO processor 266 where applicable, further processed by modulators 254a through 254r (e.g., for discrete Fourier transform spread OFDM (DFT-s-OFDM), CP-OFDM, etc.), and transmitted to the base station 110. At the base station 110, the uplink signals from the UE 120 and other UEs may be received by the antenna 234, processed by the demodulator 254, detected by the MIMO detector 236 (where applicable), and further processed by the receive processor 238 to obtain the decoded data and control information transmitted by the UE 120. The receive processor 238 may provide the decoded data to the data sink 239, and provide the decoded control information to the controller / processor 240. The base station 110 may include a communication unit 244 and communicate with the network controller 130 via the communication unit 244. The network controller 130 may include a communication unit 294, a controller / processor 290, and a memory 292.

[0048] The controller / processor 240 of the base station 110, the controller / processor 280 of the UE 120, and / orFigure 2 Any other components of may perform one or more techniques associated with non-terrestrial timing compensation, as described in more detail elsewhere. For example, the controller / processor 240 of the base station 110, the controller / processor 280 of the UE 120, and / or Figure 2 any other components of may perform or direct operations of, for example Figure 8 the processes of and / or other processes as described. The memories 242 and 282 may store data and program codes for the base station 110 and the UE 120, respectively. The scheduler 246 may schedule the UE for data transmission on the downlink and / or uplink.

[0049] In some aspects, the UE 120 may include components for modulation, components for application, components for transformation, and components for transmission. Such components may include one or more components of the UE 120 described in connection with Figure 2 .

[0050] As indicated above, Figure 2 is provided merely as an example. Other examples may be different from the examples described with reference to Figure 2 .

[0051] The deployment of a communication system (such as a 5G New Radio (NR) system) may be arranged in various ways with various components or constituent parts. In a 5G NR system or network, network nodes, network entities, mobility elements of the network, radio access network (RAN) nodes, core network nodes, network elements, or network equipment (such as a base station (BS)) or one or more units (or one or more components) performing base station functions may be implemented in an aggregated or disaggregated architecture. For example, a BS (such as a Node B (NB), evolved NB (eNB), NR BS, 5G NB, access point (AP), transmit and receive point (TRP), or cell, etc.) may be implemented as an aggregated base station (also referred to as a stand-alone BS or monolithic BS) or a disaggregated base station.

[0052] A converged base station can be configured to utilize a radio protocol stack that is physically or logically integrated within a single RAN node. A split base station can be configured to utilize a protocol stack that is physically or logically distributed between two or more units, such as one or more central or centralized units (CUs), one or more distributed units (DUs), or one or more radio units (RUs). In some aspects, a CU can be implemented within a RAN node, and one or more DUs can be co-located with the CU, or alternatively, can be geographically or virtually distributed across one or more other RAN nodes. A DU can be implemented to communicate with one or more RUs. Each of the CU, DU, and RU can also be implemented as a virtual unit (e.g., a virtual central unit (VCU), a virtual distributed unit (VDU), or a virtual radio unit (VRU)).

[0053] Base station type operations or network designs can consider the converged characteristics of base station functionality. For example, a split base station can be used in an integrated access backhaul (IAB) network, an open radio access network (O-RAN, such as a network configuration advocated by the O-RAN Alliance), or a virtualized radio access network (vRAN, also known as a cloud radio access network (C-RAN)). Splitting can include distributing functions across two or more units at various physical locations, as well as virtualizing the function of at least one unit, which can enable flexibility in network design. The various units of a split base station or a split RAN architecture can be configured for wired or wireless communication with at least one other unit.

[0054] In some cases, different types of devices that support different types of applications and / or services can coexist in a cell. Examples of different types of devices include UE mobile phones, customer premises equipment (CPE), vehicles, Internet of Things (IoT) devices, etc. Examples of different types of applications include ultra-reliable low-latency communication (URLLC) applications, massive machine type communication (mMTC) applications, enhanced mobile broadband (eMBB) applications, vehicle-to-everything (V2X) applications, etc. Additionally, in some cases, a single device can support different applications or services simultaneously.

[0055] Figure 3FIG. shows a diagram illustrating an exemplary disaggregated base station 300 architecture. The disaggregated base station 300 architecture may include one or more central units (CUs) 310, which may communicate directly with the core network 320 via a backhaul link, or indirectly with the core network 320 through one or more disaggregated base station units (such as a near real-time (near RT) RAN intelligent controller (RIC) 325 via an E2 link, or a non-real-time (non RT) RIC 315 associated with a service management and orchestration (SMO) framework 305, or both). The CU 310 may communicate with one or more distributed units (DUs) 330 via a respective midhaul link (such as an F1 interface). The DU 330 may communicate with one or more radio units (RUs) 340 via a respective fronthaul link. The RU 340 may communicate with a respective UE 120 via one or more radio frequency (RF) access links. In some embodiments, the UE 120 may be served simultaneously by multiple RUs 340.

[0056] Each of these units (e.g., CU 310, DU 330, RU 340, and near RT RIC 325, non RT RIC 315, and SMO framework 305) may include one or more interfaces, or may be coupled to one or more interfaces configured to receive or transmit signals, data, or information (collectively referred to as signals) via a wired or wireless transmission medium. Each of the units or the associated processor or controller providing instructions to the communication interfaces of these units may be configured to communicate with one or more of the other units via the transmission medium. For example, the units may include a wired interface configured to receive or transmit signals to one or more of the other units via a wired transmission medium. Additionally, the units may include a wireless interface, which may include a receiver, a transmitter, or a transceiver (such as a radio frequency (RF) transceiver) configured to receive or transmit signals, or both, to one or more of the other units over a wireless transmission medium.

[0057] In some aspects, the CU 310 may host one or more higher layer control functions. Such control functions may include Radio Resource Control (RRC), Packet Data Convergence Protocol (PDCP), Service Data Adaptation Protocol (SDAP), etc. Each control function may be implemented using an interface configured to signal with other control functions hosted by the CU 310. The CU 310 may be configured to handle user plane functionality (e.g., Central Unit - User Plane (CU-UP)), control plane functionality (e.g., Central Unit - Control Plane (CU-CP)), or a combination thereof. In some embodiments, the CU 310 may be logically split into one or more CU-UP units and one or more CU-CP units. When implemented in an O-RAN configuration, the CU-UP units may communicate bidirectionally with the CU-CP units via an interface such as the E1 interface. As needed, the CU 310 may be implemented to communicate with the DU 330 for network control and signaling.

[0058] The DU 330 may correspond to a logical unit that includes one or more base station functions for controlling the operation of one or more RUs 340. In some aspects, the DU 330 may host one or more of the Radio Link Control (RLC) layer, Medium Access Control (MAC) layer, and one or more high Physical (PHY) layers (such as modules for forward error correction (FEC) encoding and decoding, scrambling, modulation and demodulation, etc.) at least in part depending on a functional split (such as the functional split defined by the Third Generation Partnership Project (3GPP)). In some aspects, the DU 330 may also host one or more low PHY layers. Each layer (or module) may be implemented using an interface configured to signal with other layers (and modules) hosted by the DU 330 or with control functions hosted by the CU 310.

[0059] The lower layer functionality may be implemented by one or more RUs 340. In some deployments, the RUs 340 controlled by the DU 330 may correspond to logical nodes that host RF processing functions or low PHY layer functions (such as performing Fast Fourier Transform (FFT), inverse FFT (iFFT), digital beamforming, Physical Random Access Channel (PRACH) extraction and filtering, etc.) or both at least in part based on a functional split (such as a lower layer functional split). In such an architecture, the RUs 340 may be implemented to handle over-the-air (OTA) communication with one or more UEs 120. In some embodiments, the real-time and non-real-time aspects of communicating with the control plane and user plane of the RUs 340 may be controlled by the corresponding DU 330. In some scenarios, this configuration may enable the DU 330 and CU 310 to be implemented in a cloud-based RAN architecture such as a virtual radio access network (vRAN) architecture.

[0060] The SMO framework 305 can be configured to support the RAN deployment and orchestration of non-virtualized network elements and virtualized network elements. For non-virtualized network elements, the SMO framework 305 can be configured to support the deployment of dedicated physical resources for RAN coverage requirements, and these dedicated physical resources can be managed via operation and maintenance interfaces (such as the O1 interface). For virtualized network elements, the SMO framework 305 can be configured to interact with a cloud computing platform (such as the Open Cloud (O-cloud) 390) to perform network element lifecycle management (such as instantiating virtualized network elements) via a cloud computing platform interface (such as the O2 interface). Such virtualized network elements can include, but are not limited to, the CU 310, DU 330, RU 340, and the Near RT RIC 325. In some specific implementations, the SMO framework 305 can communicate with the hardware aspect of the 4G RAN (such as the Open eNB (O-eNB) 311) via the O1 interface. Additionally, in some specific implementations, the SMO framework 305 can communicate directly with one or more RUs 340 via the O1 interface. The SMO framework 305 can also include a Non-RT RIC 315 configured to support the functionality of the SMO framework 305.

[0061] The Non-RT RIC 315 can be configured to include logical functions that can enable non-real-time control and optimization of RAN elements and resources, artificial intelligence / machine learning (AI / ML) workflows including model training and update, or policy-based guidance of applications / features in the Near RT RIC 325. The Non-RT RIC 315 can be coupled to or communicate with the Near RT RIC 325 (such as via the A1 interface). The Near RT RIC 325 can be configured to include logical functions that can enable near-real-time control and optimization of RAN elements and resources via data collection and actions on an interface (such as via the E2 interface) that connects one or more CUs 310, one or more DUs 330, or both, and the O-eNB 311 to the Near RT RIC 325.

[0062] In some embodiments, to generate the AI / ML models to be deployed in the near-RT RIC 325, the non-RT RIC 315 may receive parameters or external enrichment information from an external server. Such information may be utilized by the near-RT RIC 325 and may be received from non-network data sources or from network functions at the SMO framework 305 or the non-RT RIC 315. In some examples, the non-RT RIC 315 or the near-RT RIC 325 may be configured to regulate RAN behavior or performance. For example, the non-RT RIC 315 may monitor long-term trends and patterns of performance and employ an AI / ML model to perform corrective actions via the SMO framework 305 (such as reconfiguration via O1) or via the creation of RAN management policies (such as A1 policies).

[0063] Figure 4 is a block diagram illustrating an example of a wireless communication network 400 that supports compensation for timing errors in a non-terrestrial network (NTN) in accordance with aspects of the present disclosure. In some examples, the wireless communication network 400 may implement aspects of the wireless network 100. The wireless communication network 400 may include a base station 110 and a UE 120, which may be examples of the corresponding devices as referenced Figure 1 , Figure 2 and Figure 3 described. For example, the wireless communication network 400 may be a non-terrestrial network, which may include a base station 110, a UE 120, and a satellite 440. The satellite 440 may relay communications for the base station (e.g., base station 110) and the mobile terminal (e.g., UE 120). The base station 110 may also be referred to as a gateway. The geographical area associated with the transmission beam of the satellite 440 may be referred to as a beam coverage area 430, and when the UE 120 is located within the beam coverage area 430, the UE 120 may communicate with the satellite 440.

[0064] The base station 110 may perform communication procedures (e.g., radio resource control (RRC) procedures such as a cell capture procedure, a random access procedure, an RRC connection procedure, or an RRC configuration procedure) with the UE 120. The base station 110 may be configured with multiple antennas, which may be used for directional or beamformed transmissions. As part of the communication procedure, the base station 110 may establish a two-way communication link 410 for communicating with the UE 120. Additionally or alternatively, as part of the communication procedure, the base station 110 may configure the UE 120 via RRC signaling with a configuration 415 (e.g., time and frequency resources, reference signal periodicity, or an indication of the symbols of the time slots for transmitting reference signals). Although direct communication is shown in Figure 4 , the present disclosure focuses on the communication of the UE 120 to the base station 110 via the satellite 440.

[0065] Satellite 440 may generate satellite information (e.g., ephemeris information) associated with communications between satellite 440, UE 120, and base station 110. For example, satellite 440 may determine a propagation delay associated with transmissions between satellite 440, UE 120, and base station 110. In some cases, the propagation delay may be based on the distance d from satellite 440 to a point 405 (e.g., the center) of beam coverage area 430. In other cases, the propagation delay may be a factor of the distance d, which may correspond to the round-trip distance between base station 110 and satellite 440. Additionally or alternatively, the propagation delay may be an estimated round-trip delay or round-trip time between UE 120 and base station 110, which may be at least partially based on the distance d and / or 2d. It should be noted that the distance d may not reflect the exact distance from satellite 440 to UE 120. For example, UE 120 may be located at the edge of beam coverage area 430, and the distance from satellite 440 may be different from the distance d. Aspects of the present disclosure are capable of compensating for the distance difference using timing pre-compensation to improve timing synchronization. Errors in timing synchronization may result in residual timing errors, thereby degrading performance in non-terrestrial networks. Aspects of the present disclosure relate to improvements in timing synchronization.

[0066] Satellite 440 may send the satellite information to base station 110 and / or UE 120 that may be located within beam coverage area 430 via wireless communication link 435. In some cases, satellite 440 may update the satellite information according to a pre-configured schedule (e.g., update rate) and send it to base station 110 and / or UE 120. The pre-configured schedule may be based on the speed of satellite 440. For example, the speed of satellite 440 may result in a maximum round-trip time change rate of 50 μs per second. That is, for each second of movement of satellite 440, the round-trip communication time between satellite 440 and UE 120 may change by, for example, 50 μs. The round-trip time change rate may also vary based on the movement (e.g., orbit) of the satellite. In this case, satellite 440 may update the satellite information multiple times per second. Additionally or alternatively, for example, as part of configuration 415, base station 110 may send the satellite information to UE 120 via two-way communication link 410. In some cases, base station 110 may send the satellite information to UE 120 based on a pre-configured schedule (e.g., the update rate of satellite 440).

[0067] Satellite information may include the velocity of satellite 440. In some cases, the velocity of satellite 440 may be defined by or related to the expression v×cos(α), where α is the angle between the velocity vector v and the distance vector d. The UE 120 may use the velocity of satellite 440 to determine the rate of change of round-trip time. In some cases, the UE 120 may use the velocity of satellite 440 to determine the rate of change of round-trip time based at least in part on the position of the UE 120 relative to point 405 of the beam coverage area 430. In some examples, using the velocity of satellite 440, the rate of change of round-trip time may be defined by the expression -2v×cos(α) / C, where α is the angle between the velocity vector v and the distance vector d, and c is the speed of light. Thus, if an uplink transmission is scheduled to occur at time t0 with a timing adjustment t a for transmission, the actual transmission time of the UE 120 may be t0 + t a . For a subsequent uplink transmission scheduled to occur at time t a +Δt, in the absence of a new timing adjustment provided by the base station 110, the actual transmission time of the UE 120 may be t a +Δt×(-2v×cos(α) / c).

[0068] Figure 5 is a block diagram illustrating an example of an alternative network configuration of a wireless communication network 500 that supports compensation for timing errors in a non-terrestrial network (NTN) in accordance with aspects of the present disclosure. In Figure 5 the example, the non-terrestrial base station 110-b is located on satellite 540. The non-terrestrial base station 110-b communicates with the core network 530 via a wireless communication link 535. The UE 120 communicates with the non-terrestrial base station 110-b via a wireless communication link 535. In other aspects, (not shown) the base station is located on the ground and provides a feeder link between the ground gateway and the satellite.

[0069] In a non-terrestrial network (NTN), the round-trip time from base station 110-b to UE 120 via intermediate satellite 540 can be quite long. Similarly, the round-trip time between non-terrestrial base station 110-b on satellite 540 and UE 120 can be long. The large round-trip time is due to the large distance that the electromagnetic wave traverses. The imperfect timing synchronization caused by the round-trip time may lead to performance degradation in the non-terrestrial network. For example, as noted above, in the case of uplink transmission for low Earth orbit (LEO) satellite communication, due to the same center compensation of the uplink resource allocation (or uplink bandwidth part in frequency) for each UE 120, residual time drift may occur. This timing error can be regarded as a phase rotation in the frequency domain. The phase rotation depends on the frequency resources (e.g., subcarriers) allocated to UE 120. For example, if multiple subcarriers are allocated, the phase rotation may affect each subcarrier differently, as described in more detail below. Each subcarrier can have its own index.

[0070] Aspects of the present disclosure actively compensate for the subcarrier-index-based phase rotation of each subcarrier in the frequency domain at the UE side. In some examples, it is assumed that the UE knows the timing error (or at least an estimate of the timing error) and the subcarrier allocation. After transforming from the frequency domain to the time domain, as a result of the phase change applied to each subcarrier in the frequency domain, the correct timing drift of each symbol can be obtained, such that the entire sequence is received at the receiver without significant timing synchronization error.

[0071] The timing error experienced by the UE varies over time because the satellite moves over time. Therefore, each orthogonal frequency division multiplexing (OFDM) symbol has a different residual drift. The parameter ∈ i represents the timing error (in units of number of samples) in a given OFDM symbol associated with each UE i in the system. The parameter N FFT represents the fast Fourier transform (FFT) size (e.g., the number of samples in a symbol, also known as the window), and the parameter N CP represents the cyclic prefix (CP) length. For example, if the timing error is within a reasonable range and if the timing error ∈ i is less than the CP length, then the timing error ∈ i is converted to a phase φ i, l, which is applied to the modulation symbol as a product with the complex exponential term in the frequency domain, and this complex exponential term is given by where m i,e is the index of the l-th subcarrier allocated to UE i, and the parameter j represents the imaginary number.

[0072] Since the satellite moves relative to the UE, the amount of drift changes with respect to the previous symbol for each symbol. For example, the residual drift Δ i (measured, for example, in μs / s) results in a timing error ∈ i : ∈ i = kΔ i (N fFT + N CP )10 -6 , where k is an index representing the number of OFDM symbols. In other words, for the first OFDM symbol, the timing error ∈ i is based on the residual drift Δ i (N FFT + N cp )10 -6 of that symbol, while for the second OFDM symbol, the timing error ∈ i is based on the residual drift 2xΔ i (N FFT + N CP )10 -6 of the second symbol. According to aspects of the present disclosure, before performing the IFFT (transforming from the frequency domain to the time domain) and transmitting on the uplink, each UE rotates the corresponding subcarrier in the frequency domain by a phase φ i, l (modulating the symbol by multiplying by a complex exponential ). This rotation reduces the performance loss based on the timing error in the non-terrestrial network.

[0073] Figure 6 is a block diagram illustrating phase compensation for a single subcarrier according to aspects of the present disclosure. Single-carrier allocation may be applicable to, for example, narrowband Internet of Things (IoT) devices. In Figure 6 example, a first UE (UE 1) and a second UE (UE 2) each include a plurality of components such as a modulator 602, a mixer 604, an inverse fast Fourier transformer (IFFT) 606, and a parallel-to-serial converter (P / S) 608. The modulator 602 modulates the signal by processing the output symbol stream to obtain an output sample stream in the frequency domain. For each OFDM symbol, the mixer 604 performs phase compensation on a single subcarrier by adjusting the signal by where is for the subcarrier with index 1. For the first UE (UE 1), this adjustment corresponds to where Since the second UE (UE 2) has a different timing error ∈2, for the second UE (UE 2), this adjustment corresponds to where

[0074] After phase compensation, the IFFT 606 transforms the signal from the frequency domain to the time domain, and the P / S 608 serializes any parallel streams. Since a single subcarrier is used in the example of Figure 6 , the sample stream is not parallel. Before the digital-to-analog converter (DAC) 612 converts the digital signal into an analog signal, the C / P module 610 inserts a cyclic prefix (CP) into the serial bits. The analog signal is fed to the radio frequency front end (RFFE) 614 for transmission to the satellite.

[0075] Figure 7 is a block diagram showing phase compensation for multiple subcarriers according to aspects of the present disclosure. In the example of Figure 7 , each UE (UE 1 and UE 2) is assigned multiple subcarriers. Similar to that described with reference to Figure 6 , in Figure 7 , the first UE (UE1) and the second UE (UE 2) each include a modulator 602, a mixer 604, an inverse fast Fourier transformer (IFFT) 606, and a parallel-to-serializer (P / S) 608. The modulator 602 modulates the signal by processing the output symbol stream to obtain an output sample stream in the frequency domain. For each OFDM symbol, the mixer 604 performs phase compensation for each subcarrier by adjusting the signal by , where is for the subcarrier with index l. For the first UE (UE 1) and the first subcarrier, the adjustment corresponds to where For the first UE (UE 1) and the second subcarrier, the adjustment corresponds to where For the first UE (UE 1) and the third subcarrier, the adjustment corresponds to where For the second UE (UE 2) and the first subcarrier, the adjustment corresponds to where For the second UE (UE 2) and the second subcarrier, the adjustment corresponds to where For the second UE (UE 2) and the third subcarrier, the adjustment corresponds to where Figure 7 The phase compensation in

[0076] After phase compensation, the IFFT 606 transforms the signals on each carrier from the frequency domain to the time domain, and the P / S 608 serializes the parallel samples. Before the digital-to-analog converter (DAC) 612 converts the digital signal into an analog signal, the C / P module 610 inserts a cyclic prefix (CP) into the serial bits. The analog signal is fed to a radio frequency front end (RFFE) 614 for transmission to a satellite. Since the compensation is performed specifically for each UE and each subcarrier, the base station does not need to adjust its sampling rate when performing fast Fourier transform (FFT) processing for multiple UEs and subcarriers simultaneously.

[0077] Although the present disclosure has been described with respect to phase compensation, other embodiments are also contemplated. For example, each UE may compensate for timing errors at the symbol level (e.g., in the time domain) instead of performing phase compensation. A sampling rate change may occur at the IFFT 606 such that the samples are transmitted to the P / S 608 at different times. Each sample may be delayed or transmitted earlier than normal timing. For example, instead of transmitting samples at times t1, t2, t3, etc., the samples may be transmitted at times t1, t2±δ, t3±δ, etc. The time difference (δ) may depend on the amount of drift that occurs in the symbol. In another embodiment, instead of performing phase compensation, a small amount of interference caused by drift may be tolerated.

[0078] As shown above, Figures 4 to 7 is provided as an example. Other examples may be different from the examples described with respect to Figures 4 to 7 the examples described.

[0079] Figure 8 is a flowchart illustrating an example phase compensation process 800, such as may be performed by a UE, in accordance with various aspects of the present disclosure. The example process 800 is an example of proactive compensation for uplink timing errors in a non-terrestrial network (NTN). The operations of the process 800 may be implemented by a UE 120.

[0080] At block 802, a user equipment (UE) modulates a symbol stream onto at least one subcarrier to generate an uplink signal in the frequency domain for transmission to a receiver in a non-terrestrial network. For example, the UE (e.g., using the controller / processor 280, the memory 282, and / or similar elements) may modulate the symbol stream.

[0081] At block 804, a user equipment (UE) applies a phase rotation amount to at least one subcarrier in the frequency domain. For example, the UE (e.g., controller / processor 280, memory 282, and / or similar elements) may apply the phase rotation amount. In some aspects, the phase rotation amount is based on an amount of timing error associated with communication from the UE to the receiver. When the amount of timing error is less than a cyclic prefix (CP) length configured for an uplink signal, the UE may apply phase rotation. In some aspects, the phase rotation amount is based on a frequency allocation used by the UE for uplink transmission. In other aspects, the phase rotation amount is linear in a subcarrier index within a frequency allocation of a multi-carrier allocation. In still other aspects, the phase rotation amount is based on: a fast Fourier transform (FFT) size, a cyclic prefix (CP) length, an index of at least one subcarrier within a frequency allocation used by the UE for uplink transmission, and / or a residual time drift associated with communication from the UE to the receiver. In other aspects, the phase rotation amount is based on an orthogonal frequency division multiplexing (OFDM) symbol index within an uplink resource allocation in the time domain. In these aspects, the phase rotation amount is linear in the OFDM symbol index within the uplink resource allocation in the time domain.

[0082] At block 806, the user equipment (UE) transforms the uplink signal from the frequency domain to a time domain uplink signal. For example, the UE (e.g., controller / processor 280, memory 282, and / or similar elements) may transform the uplink signal with an inverse fast Fourier transform (IFFT).

[0083] At block 808, after applying the phase rotation to at least one subcarrier, the user equipment (UE) transmits the time domain uplink signal to the receiver. For example, the UE (e.g., antenna 252, DEMOD / MOD 254, TX MIMO processor 266, transmit processor 264, controller / processor 280, memory 282, and / or similar elements) may transmit the time domain uplink signal.

[0084] Example aspects

[0085] Aspect 1: A method for wireless communication by a user equipment (UE), the method comprising: modulating a symbol stream onto at least one subcarrier to generate an uplink signal in the frequency domain for transmission to a receiver in a non-terrestrial network; applying a phase rotation amount to the at least one subcarrier in the frequency domain; transforming the uplink signal from the frequency domain into a time domain uplink signal; and transmitting the time domain uplink signal to the receiver after applying the phase rotation to the at least one subcarrier.

[0086] Aspect 2: The method according to aspect 1, wherein the amount of phase rotation is based on an amount of timing error associated with communication from the UE to the receiver.

[0087] Aspect 3: The method according to aspect 1 or 2, wherein the amount of phase rotation is applied when the amount of timing error is less than a cyclic prefix (CP) length configured for the uplink signal.

[0088] Aspect 4: The method according to aspect 1, 2, or 3, wherein the amount of phase rotation is based on a frequency allocation used by the UE for uplink transmission.

[0089] Aspect 5: The method according to any one of the preceding aspects, wherein the amount of phase rotation is linear in a subcarrier index within a frequency allocation of a multi-carrier allocation.

[0090] Aspect 6: The method according to any one of the preceding aspects, wherein the amount of phase rotation is based on at least one of: a fast Fourier transform (FFT) size, a cyclic prefix (CP) length, an index of the at least one subcarrier within a frequency allocation used by the UE for uplink transmission, and a residual time drift associated with communication from the UE to the receiver.

[0091] Aspect 7: The method according to any one of the preceding aspects, wherein the amount of phase rotation is based on an orthogonal frequency division multiplexing (OFDM) symbol index within an uplink resource allocation in the time domain.

[0092] Aspect 8: The method according to any one of the preceding aspects, wherein the amount of phase rotation is linear in the OFDM symbol index within the uplink resource allocation in the time domain.

[0093] Aspect 9: An apparatus for wireless communication by a user equipment (UE), the apparatus comprising: a memory; and at least one processor coupled to the memory, the at least one processor configured to: modulate a symbol stream onto at least one subcarrier to generate an uplink signal in the frequency domain for transmission to a receiver in a non-terrestrial network; apply an amount of phase rotation to the at least one subcarrier in the frequency domain; transform the uplink signal from the frequency domain into a time-domain uplink signal; and transmit the time-domain uplink signal to the receiver after applying the phase rotation to the at least one subcarrier.

[0094] Aspect 10: The apparatus according to aspect 9, wherein the amount of phase rotation is based on an amount of timing error associated with communication from the UE to the receiver.

[0095] Aspect 11: The apparatus according to aspect 9 or 10, wherein the at least one processor is further configured to apply the phase rotation amount when the timing error amount is less than a cyclic prefix (CP) length configured for the uplink signal.

[0096] Aspect 12: The apparatus according to any one of aspects 9 to 11, wherein the phase rotation amount is based on a frequency allocation used by the UE for uplink transmission.

[0097] Aspect 13: The apparatus according to any one of aspects 9 to 12, wherein the phase rotation amount is linear in subcarrier indices within a frequency allocation of a multi-carrier allocation.

[0098] Aspect 14: The apparatus according to any one of aspects 9 to 13, wherein the phase rotation amount is based on at least one of the following: fast Fourier transform (FFT) size, cyclic prefix (CP) length, an index of the at least one subcarrier within a frequency allocation used by the UE for uplink transmission, and a residual time drift associated with communication from the UE to the receiver.

[0099] Aspect 15: The apparatus according to any one of aspects 9 to 14, wherein the phase rotation amount is based on an orthogonal frequency division multiplexing (OFDM) symbol index within an uplink resource allocation in the time domain.

[0100] Aspect 16: The apparatus according to any one of aspects 9 to 15, wherein the phase rotation amount is linear in OFDM symbol indices within the uplink resource allocation in the time domain.

[0101] Aspect 17: An apparatus for wireless communication by a user equipment (UE), the apparatus comprising: means for modulating a symbol stream onto at least one subcarrier to generate an uplink signal in the frequency domain for transmission to a receiver in a non-terrestrial network; means for applying a phase rotation amount to the at least one subcarrier in the frequency domain; means for transforming the uplink signal from the frequency domain into a time-domain uplink signal; and means for transmitting the time-domain uplink signal to the receiver after applying the phase rotation to the at least one subcarrier.

[0102] Aspect 18: The apparatus according to aspect 17, wherein the phase rotation amount is based on a timing error amount associated with communication from the UE to the receiver.

[0103] Aspect 19: The apparatus according to aspect 17 or 18, the apparatus further comprising means for applying the phase rotation amount when the timing error amount is less than a cyclic prefix (CP) length configured for the uplink signal.

[0104] Aspect 20: The apparatus according to any one of aspects 17 to 19, wherein the amount of phase rotation is based on the frequency allocation used by the UE for uplink transmission.

[0105] Aspect 21: The apparatus according to any one of aspects 17 to 20, wherein the amount of phase rotation is linear in the subcarrier indices within the frequency allocation of the multi-carrier allocation.

[0106] Aspect 22: The apparatus according to any one of aspects 17 to 21, wherein the amount of phase rotation is based on at least one of the following: fast Fourier transform (FFT) size, cyclic prefix (CP) length, the index of the at least one subcarrier within the frequency allocation used by the UE for uplink transmission, and the residual time drift associated with the communication from the UE to the receiver.

[0107] Aspect 23: The apparatus according to any one of aspects 17 to 22, wherein the amount of phase rotation is based on the orthogonal frequency division multiplexing (OFDM) symbol index within the uplink resource allocation in the time domain.

[0108] Aspect 24: The apparatus according to any one of aspects 17 to 23, wherein the amount of phase rotation is linear in the OFDM symbol index within the uplink resource allocation in the time domain.

[0109] Aspect 25: A non-transitory computer-readable medium having program code recorded thereon, the program code being executed by a processor at a user equipment (UE) and including: program code for modulating a symbol stream onto at least one subcarrier to generate an uplink signal in the frequency domain for transmission to a receiver in a non-terrestrial network; program code for applying an amount of phase rotation to the at least one subcarrier in the frequency domain; program code for transforming the uplink signal from the frequency domain into a time-domain uplink signal; and program code for transmitting the time-domain uplink signal to the receiver after applying the phase rotation to the at least one subcarrier.

[0110] Aspect 26: The non-transitory computer-readable medium according to aspect 25, wherein the amount of phase rotation is based on the amount of timing error associated with the communication from the UE to the receiver.

[0111] Aspect 27: The non-transitory computer-readable medium according to aspect 25 or 26, wherein the program code further includes program code for applying the amount of phase rotation when the amount of timing error is less than the cyclic prefix (CP) length configured for the uplink signal.

[0112] Aspect 28: The non-transitory computer-readable medium according to aspect 25, 26, or 27, wherein the amount of phase rotation is based on the frequency allocation used by the UE for uplink transmission.

[0113] Aspect 29: The non-transitory computer-readable medium according to any one of aspects 25 to 28, wherein the amount of phase rotation is linear in the subcarrier indices within the frequency allocation of a multi-carrier allocation.

[0114] Aspect 30: The non-transitory computer-readable medium according to claim 25, wherein the amount of phase rotation is based on at least one of the following: fast Fourier transform (FFT) size, cyclic prefix (CP) length, the index of the at least one subcarrier within the frequency allocation used by the UE for uplink transmission, and the residual time drift associated with the communication from the UE to the receiver.

[0115] The foregoing disclosure provides illustration and description, but is not intended to be exhaustive or to limit the aspects to the precise forms disclosed. Modifications and variations can be made in light of the above disclosure, or can be obtained from practice of the aspects.

[0116] As used, the term "component" is intended to be broadly construed as hardware, firmware, and / or a combination of hardware and software. As used, a processor is implemented using hardware, firmware, and / or a combination of hardware and software.

[0117] Some aspects are described in connection with a threshold. As used, depending on the context, meeting a threshold can mean a value greater than the threshold, greater than or equal to the threshold, less than the threshold, less than or equal to the threshold, equal to the threshold, not equal to the threshold, etc.

[0118] It will be apparent that the described systems and / or methods can be implemented in different forms of hardware, firmware, and / or a combination of hardware and software. The actual specific control hardware or software code used to implement these systems and / or methods does not limit the aspects. Accordingly, the operations and performance of these systems and / or methods are described without reference to specific software code, it should be understood that software and hardware can be designed to implement these systems and / or methods based at least in part on this description.

[0119] Although specific combinations of features are set forth in the claims and / or disclosed in the specification, these combinations are not intended to limit the disclosure of each aspect. In fact, many of these features may be combined in ways not specifically set forth in the claims and / or not disclosed in the specification. Although each dependent claim listed below may directly depend on only one claim, the disclosure of each aspect includes each dependent claim in combination with every other claim in the claim set. A phrase referring to "at least one" of a list of items refers to any combination of those items, including a single member. For example, "at least one of a, b, or c" is intended to cover a, b, c, a-b, a-c, b-c, and a-b-c, as well as any combination having multiple of the same element (e.g., a-a, a-a-a, a-a-b, a-a-c, a-b-b, a-c-c, b-b, b-b-b, b-b-c, c-c, and c-c-c, or any other ordering of a, b, and c).

[0120] An element, act, or instruction used should not be construed as critical or essential unless expressly described as such. Further, as used herein, the articles "a" and "an" are intended to include one or more and may be used interchangeably with "one or more." Further, as used herein, the terms "set" and "group" are intended to include one or more (e.g., related items, unrelated items, combinations of related and unrelated items, etc.) and may be used interchangeably with "one or more." If only intending to refer to a single item, the phrase "only one" or similar language will be used. Further, as used herein, the term "having" and the like are intended to be open-ended terms. Further, the phrase "based on" is intended to mean "at least partially based on" unless expressly stated otherwise.

Claims

1. A method for wireless communication by a user equipment (UE), the method comprising: Modulating a symbol stream onto at least one subcarrier to generate an uplink signal in the frequency domain for transmission to a receiver in a non-terrestrial network; Applying a phase rotation amount to the at least one subcarrier in the frequency domain; Transforming the uplink signal from the frequency domain into a time-domain uplink signal; And After applying the phase rotation to the at least one subcarrier, transmitting the time-domain uplink signal to the receiver.

2. The method according to claim 1, wherein the phase rotation amount is based on an amount of timing error associated with communication from the UE to the receiver.

3. The method according to claim 2, wherein the phase rotation amount is applied when the amount of timing error is less than a cyclic prefix (CP) length configured for the uplink signal.

4. The method according to claim 1, wherein the phase rotation amount is based on a frequency allocation used by the UE for uplink transmission.

5. The method according to claim 1, wherein the phase rotation amount is linear in a subcarrier index within a frequency allocation of a multi-carrier allocation.

6. The method according to claim 1, wherein the phase rotation amount is based on at least one of: a fast Fourier transform (FFT) size, a cyclic prefix (CP) length, an index of the at least one subcarrier within a frequency allocation used by the UE for uplink transmission, and a residual time drift associated with communication from the UE to the receiver.

7. The method according to claim 1, wherein the phase rotation amount is based on an orthogonal frequency division multiplexing (OFDM) symbol index within an uplink resource allocation in the time domain.

8. The method according to claim 7, wherein the phase rotation amount is linear in the OFDM symbol index within the uplink resource allocation in the time domain.

9. An apparatus for wireless communication by a user equipment (UE), the apparatus comprising: A memory; And At least one processor coupled to the memory, the at least one processor being configured to: Modulate a symbol stream onto at least one subcarrier to generate an uplink signal in the frequency domain for transmission to a receiver in a non-terrestrial network; Apply a phase rotation amount to the at least one subcarrier in the frequency domain; Transform the uplink signal from the frequency domain into a time-domain uplink signal; And After applying the phase rotation to the at least one subcarrier, transmit the time-domain uplink signal to the receiver.

10. The apparatus according to claim 9, wherein the phase rotation amount is based on an amount of timing error associated with communication from the UE to the receiver.

11. The apparatus according to claim 10, wherein the at least one processor is further configured to apply the phase rotation amount when the amount of timing error is less than a cyclic prefix (CP) length configured for the uplink signal.

12. The apparatus according to claim 9, wherein the amount of phase rotation is based on the frequency allocation used by the UE for uplink transmission.

13. The apparatus according to claim 9, wherein the amount of phase rotation is linear in the subcarrier indices within the frequency allocation of a multi-carrier allocation.

14. The apparatus according to claim 9, wherein the amount of phase rotation is based on at least one of: Fast Fourier Transform (FFT) size, cyclic prefix (CP) length, the index of the at least one subcarrier within the frequency allocation used by the UE for uplink transmission, and the residual time drift associated with the communication from the UE to the receiver.

15. The apparatus according to claim 9, wherein the amount of phase rotation is based on the Orthogonal Frequency Division Multiplexing (OFDM) symbol index within the uplink resource allocation in the time domain.

16. The apparatus according to claim 15, wherein the amount of phase rotation is linear in the OFDM symbol index within the uplink resource allocation in the time domain.

17. An apparatus for wireless communication by a User Equipment (UE), the apparatus comprising: means for modulating a symbol stream onto at least one subcarrier to generate an uplink signal in the frequency domain for transmission to a receiver in a non-terrestrial network; means for applying an amount of phase rotation to the at least one subcarrier in the frequency domain; means for transforming the uplink signal from the frequency domain into a time domain uplink signal; and means for transmitting the time domain uplink signal to the receiver after applying the phase rotation to the at least one subcarrier.

18. The apparatus according to claim 17, wherein the amount of phase rotation is based on the amount of timing error associated with the communication from the UE to the receiver.

19. The apparatus according to claim 18, the apparatus further comprising means for applying the amount of phase rotation when the amount of timing error is less than the cyclic prefix (CP) length configured for the uplink signal.

20. The apparatus according to claim 17, wherein the amount of phase rotation is based on the frequency allocation used by the UE for uplink transmission.

21. The apparatus according to claim 17, wherein the amount of phase rotation is linear in the subcarrier indices within the frequency allocation of a multi-carrier allocation.

22. The apparatus according to claim 17, wherein the amount of phase rotation is based on at least one of: Fast Fourier Transform (FFT) size, cyclic prefix (CP) length, the index of the at least one subcarrier within the frequency allocation used by the UE for uplink transmission, and the residual time drift associated with the communication from the UE to the receiver.

23. The apparatus according to claim 17, wherein the amount of phase rotation is based on the Orthogonal Frequency Division Multiplexing (OFDM) symbol index within the uplink resource allocation in the time domain.

24. The apparatus according to claim 23, wherein the amount of phase rotation is linear in the OFDM symbol index within the uplink resource allocation in the time domain.

25. A non-transitory computer-readable medium having program code recorded thereon, the program code being executable by a processor at a user equipment (UE) and comprising: Program code for modulating a symbol stream onto at least one subcarrier to generate an uplink signal in the frequency domain for transmission to a receiver in a non-terrestrial network; Program code for applying a phase rotation amount to the at least one subcarrier in the frequency domain; Program code for transforming the uplink signal from the frequency domain into a time-domain uplink signal; And Program code for transmitting the time-domain uplink signal to the receiver after applying the phase rotation to the at least one subcarrier.

26. The non-transitory computer-readable medium according to claim 25, wherein the phase rotation amount is based on an amount of timing error associated with communication from the UE to the receiver.

27. The non-transitory computer-readable medium according to claim 26, wherein the program code further comprises program code for applying the phase rotation amount when the amount of timing error is less than a cyclic prefix (CP) length configured for the uplink signal.

28. The non-transitory computer-readable medium according to claim 25, wherein the phase rotation amount is based on a frequency allocation used by the UE for uplink transmission.

29. The non-transitory computer-readable medium according to claim 25, wherein the phase rotation amount is linear in a subcarrier index within a frequency allocation of a multi-carrier allocation.

30. The non-transitory computer-readable medium according to claim 25, wherein the phase rotation amount is based on at least one of: a fast Fourier transform (FFT) size, a cyclic prefix (CP) length, an index of the at least one subcarrier within a frequency allocation used by the UE for uplink transmission, and a residual time drift associated with communication from the UE to the receiver.

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