Patent Publication Number: US-2022232504-A1

Title: Uplink transmission timing in non-terrestrial networks

Description:
CROSS-REFERENCE TO RELATED APPLICATION AND CLAIM OF PRIORITY 
     This application claims priority under 35 U.S.C. § 119(e) to U.S. Provisional Patent Application No. 63/139,131 filed on Jan. 19, 2021; U.S. Provisional Patent Application No. 63/230,541 filed on Aug. 6, 2021; and U.S. Provisional Patent Application No. 63/237,404 filed on Aug. 26, 2021. The above-identified provisional patent applications are hereby incorporated by reference in their entirety. 
    
    
     TECHNICAL FIELD 
     The present disclosure relates generally to wireless communication systems and, more specifically, the present disclosure relates to uplink transmission timing in non-terrestrial networks (NTNs). 
     BACKGROUND 
     5th generation (5G) or new radio (NR) mobile communications is recently gathering increased momentum with all the worldwide technical activities on the various candidate technologies from industry and academia. The candidate enablers for the 5G/NR mobile communications include massive antenna technologies, from legacy cellular frequency bands up to high frequencies, to provide beamforming gain and support increased capacity, new waveform (e.g., a new radio access technology (RAT)) to flexibly accommodate various services/applications with different requirements, new multiple access schemes to support massive connections, and so on. 
     SUMMARY 
     This disclosure relates to uplink transmission timing in NTNs. 
     In one embodiment, a user equipment (UE) is provided. The UE includes a transceiver configured to receive: first information, by a system information block, indicating a value of a first time offset; second information, by a medium access control (MAC) control element (CE), indicating a value of a second time offset; and a first channel in a first time unit associated with a transmission of a second channel in a second time unit. The UE further includes a processor operably coupled to a transceiver. The processor is configured to determine a value of a third time offset based on a sum of the first and second time offsets and the second time unit based on the first time unit and the value of the third time offset. The transceiver is further configured to transmit the second channel in the second time unit. 
     In another embodiment, a base station (BS) is provided. The BS includes a transceiver configured to transmit: first information, by a system information block, indicating a value of a first time offset; second information, by a MAC CE, indicating a value of a second time offset; and a first channel in a first time unit associated with a reception of a second channel in a second time unit. The BS further includes a processor operably coupled to a transceiver. The processor is configured to determine: a value of a third time offset based on a sum of the first and second time offsets and the second time unit based on the first time unit and the value of the third time offset. The transceiver is further configured to receive the second channel in the second time unit. 
     In yet another embodiment, a method is provided. The method includes receiving: first information, by a system information block, indicating a value of a first time offset; second information, by a MAC CE, indicating a value of a second time offset; and a first channel in a first time unit associated with a transmission of a second channel in a second time unit. The method includes determining: a value of a third time offset based on a sum of the first and second time offsets and the second time unit based on the first time unit and the value of the third time offset and transmitting the second channel in the second time unit. 
     Other technical features may be readily apparent to one skilled in the art from the following figures, descriptions, and claims. 
     Before undertaking the DETAILED DESCRIPTION below, it may be advantageous to set forth definitions of certain words and phrases used throughout this patent document. The term “couple” and its derivatives refer to any direct or indirect communication between two or more elements, whether or not those elements are in physical contact with one another. The terms “transmit,” “receive,” and “communicate,” as well as derivatives thereof, encompass both direct and indirect communication. The terms “include” and “comprise,” as well as derivatives thereof, mean inclusion without limitation. The term “or” is inclusive, meaning and/or. The phrase “associated with,” as well as derivatives thereof, means to include, be included within, interconnect with, contain, be contained within, connect to or with, couple to or with, be communicable with, cooperate with, interleave, juxtapose, be proximate to, be bound to or with, have, have a property of, have a relationship to or with, or the like. The term “controller” means any device, system, or part thereof that controls at least one operation. Such a controller may be implemented in hardware or a combination of hardware and software and/or firmware. The functionality associated with any particular controller may be centralized or distributed, whether locally or remotely. The phrase “at least one of,” when used with a list of items, means that different combinations of one or more of the listed items may be used, and only one item in the list may be needed. For example, “at least one of: A, B, and C” includes any of the following combinations: A, B, C, A and B, A and C, B and C, and A and B and C. 
     Moreover, various functions described below can be implemented or supported by one or more computer programs, each of which is formed from computer readable program code and embodied in a computer readable medium. The terms “application” and “program” refer to one or more computer programs, software components, sets of instructions, procedures, functions, objects, classes, instances, related data, or a portion thereof adapted for implementation in a suitable computer readable program code. The phrase “computer readable program code” includes any type of computer code, including source code, object code, and executable code. The phrase “computer readable medium” includes any type of medium capable of being accessed by a computer, such as read only memory (ROM), random access memory (RAM), a hard disk drive, a compact disc (CD), a digital video disc (DVD), or any other type of memory. A “non-transitory” computer readable medium excludes wired, wireless, optical, or other communication links that transport transitory electrical or other signals. A non-transitory computer readable medium includes media where data can be permanently stored and media where data can be stored and later overwritten, such as a rewritable optical disc or an erasable memory device. 
     Definitions for other certain words and phrases are provided throughout this patent document. Those of ordinary skill in the art should understand that in many if not most instances, such definitions apply to prior as well as future uses of such defined words and phrases. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       For a more complete understanding of the present disclosure and its advantages, reference is now made to the following description taken in conjunction with the accompanying drawings, in which like reference numerals represent like parts: 
         FIG. 1  illustrates an example wireless network according to embodiments of the present disclosure; 
         FIG. 2  illustrates an example base station (BS) according to embodiments of the present disclosure; 
         FIG. 3  illustrates an example user equipment (UE) according to embodiments of the present disclosure; 
         FIGS. 4 and 5  illustrate example wireless transmit and receive paths according to embodiments of present disclosure; 
         FIG. 6  illustrates a method for a UE to determine a timing offset transmission of preconfigured uplink resources according to embodiments of present disclosure; 
         FIG. 7  illustrates a method for a UE to request a timing offset to adapt the transmission of preconfigured recourses that were previously configured to the UE according to embodiments of present disclosure; 
         FIG. 8  illustrates a method for a UE to update a timing offset applied to uplink transmission after coverage is obtained from a different beam of the same or different satellite or unmanned aircraft system (UAS) platform according to embodiments of present disclosure; 
         FIG. 9  illustrates a method for a UE to determine a transmission time during initial access and in connected mode according to embodiments of present disclosure; 
         FIG. 10  illustrates a method for a UE to determine a transmission timing from a cell-specific timing offset indicated by a gNB and an estimated UE-specific timing offset according to embodiments of present disclosure; 
         FIG. 11  illustrates a method for when a UE uses a first timing offset provided by a random access response (RAR) during initial access and uses a second timing offset during connected mode, where the second timing offset is based on a UE report and a gNB indication according to embodiments of present disclosure; 
         FIG. 12  illustrates a method for when a UE uses a first timing offset provided by a RAR during initial access and uses a second timing offset during connected mode, where the second timing offset is based on a UE reporting Msg3 and a gNB indication according to embodiments of present disclosure; and 
         FIG. 13  illustrates a method for when a UE uses a first timing offset provided by a RAR during initial access and uses a second timing offset during connected mode, where the second timing offset is based on a UE report and a gNB indication according to embodiments of present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
       FIGS. 1 through 13 , discussed below, and the various embodiments used to describe the principles of the present disclosure in this patent document are by way of illustration only and should not be construed in any way to limit the scope of the disclosure. Those skilled in the art will understand that the principles of the present disclosure may be implemented in any suitably-arranged system or device. 
     The following documents are hereby incorporated by reference into the present disclosure as if fully set forth herein: [1] 3GPP TS 38.211 v16.0.0, “NR; Physical channels and modulation,” [2] 3GPP TS 38.212 v16.0.0, “NR; Multiplexing and channel coding,”, [3] 3GPP TS 38.213 v16.0.0, “NR; Physical layer procedures for control,” [4] 3GPP TS 38.214 v16.0.0, “NR; Physical layer procedures for data,” [5] 3GPP TS 38.321 v15.8.0, “NR; Medium Access Control (MAC) Protocol Specification” and [6] 3GPP TS 38.331 v15.8.0, “NR; Radio Resource Control (RRC) Protocol Specification.” 
     To meet the demand for wireless data traffic having increased since deployment of the fourth generation (4G) communication systems, efforts have been made to develop and deploy an improved 5th generation (5G) or pre-5G/NR communication system. Therefore, the 5G or pre-5G communication system is also called a “beyond 4G network” or a “post long term evolution (LTE) system.” 
     The 5G communication system is considered to be implemented in higher frequency (mmWave) bands, e.g., 28 GHz or 60 GHz bands, so as to accomplish higher data rates or in lower frequency bands, such as 6 GHz, to enable robust coverage and mobility support. To decrease propagation loss of the radio waves and increase the transmission distance, the beamforming, massive multiple-input multiple-output (MIMO), Full Dimensional MIMO (FD-MIMO), array antenna, an analog beam forming, large scale antenna techniques are discussed in 5G communication systems. 
     In addition, in 5G communication systems, development for system network improvement is under way based on advanced small cells, cloud Radio Access Networks (RANs), ultra-dense networks, device-to-device (D2D) communication, wireless backhaul, moving network, cooperative communication, coordinated multi-points (CoMP), reception-end interference cancellation and the like. 
     The discussion of 5G systems and frequency bands associated therewith is for reference as certain embodiments of the present disclosure may be implemented in 5G systems. However, the present disclosure is not limited to 5G systems or the frequency bands associated therewith, and embodiments of the present disclosure may be utilized in connection with any frequency band. For example, aspects of the present disclosure may also be applied to deployment of 5G communication systems, 6G or even later releases which may use terahertz (THz) bands. 
     Depending on the network type, the term ‘base station’ (BS) can refer to any component (or collection of components) configured to provide wireless access to a network, such as transmit point (TP), transmit-receive point (TRP), an enhanced base station (eNodeB or eNB), a gNB, a macrocell, a femtocell, a WiFi access point (AP), a satellite, or other wirelessly enabled devices. Base stations may provide wireless access in accordance with one or more wireless communication protocols, e.g., 5G 3GPP New Radio Interface/Access (NR), LTE, LTE advanced (LTE-A), High Speed Packet Access (HSPA), Wi-Fi 802.11a/b/g/n/ac, and the like. The terms ‘BS,’ ‘gNB,’ and ‘TRP’ can be used interchangeably in this disclosure to refer to network infrastructure components that provide wireless access to remote terminals. Also, depending on the network type, the term ‘user equipment’ (UE) can refer to any component such as mobile station, subscriber station, remote terminal, wireless terminal, receive point, vehicle, or user device. For example, a UE could be a mobile telephone, a smartphone, a monitoring device, an alarm device, a fleet management device, an asset tracking device, an automobile, a desktop computer, an entertainment device, an infotainment device, a vending machine, an electricity meter, a water meter, a gas meter, a security device, a sensor device, an appliance, and the like. 
       FIGS. 1-3  below describe various embodiments implemented in wireless communications systems and with the use of orthogonal frequency division multiplexing (OFDM) or orthogonal frequency division multiple access (OFDMA) communication techniques. The descriptions of  FIGS. 1-3  are not meant to imply physical or architectural limitations to the manner in which different embodiments may be implemented. Different embodiments of the present disclosure may be implemented in any suitably-arranged communications system. 
       FIG. 1  illustrates an example wireless network  100  according to embodiments of the present disclosure. The embodiment of the wireless network  100  shown in  FIG. 1  is for illustration only. Other embodiments of the wireless network  100  could be used without departing from the scope of this disclosure. 
     As shown in  FIG. 1 , the wireless network  100  includes a base station, BS  101  (e.g., gNB), a BS  102 , and a BS  103 . The BS  101  communicates with the BS  102  and the BS  103 . The BS  101  also communicates with at least one network  130 , such as the Internet, a proprietary Internet Protocol (IP) network, or other data network. 
     The BS  102  provides wireless broadband access to the network  130  for a first plurality of user equipment&#39;s (UEs) within a coverage area  120  of the BS  102 . The first plurality of UEs includes a UE  111 , which may be located in a small business; a UE  112 , which may be located in an enterprise (E); a UE  113 , which may be located in a WiFi hotspot (HS); a UE  114 , which may be located in a first residence (R); a UE  115 , which may be located in a second residence (R); and a UE  116 , which may be a mobile device (M), such as a cell phone, a wireless laptop, a wireless PDA, or the like. The BS  103  provides wireless broadband access to the network  130  for a second plurality of UEs within a coverage area  125  of the BS  103 . The second plurality of UEs includes the UE  115  and the UE  116 . In some embodiments, one or more of the BSs  101 - 103  may communicate with each other and with the UEs  111 - 116  using 5G/NR, long term evolution (LTE), long term evolution-advanced (LTE-A), WiMAX, WiFi, or other wireless communication techniques. 
     Dotted lines show the approximate extents of the coverage areas  120  and  125 , which are shown as approximately circular for the purposes of illustration and explanation only. It should be clearly understood that the coverage areas associated with BSs, such as the coverage areas  120  and  125 , may have other shapes, including irregular shapes, depending upon the configuration of the BSs and variations in the radio environment associated with natural and man-made obstructions. 
     As described in more detail below, one or more of the UEs  111 - 116  include circuitry, programing, or a combination thereof for uplink transmission timing in NTNs. In certain embodiments, and one or more of the BSs  101 - 103  includes circuitry, programing, or a combination thereof for uplink transmission timing in NTNs. For example, any of BSs  101 - 103  may be a satellite in a NTN that provides wireless access to others of the BSs  102 - 103  and/or the UEs  111 - 116 . Further, any of the UEs may receive wireless access via direct or indirect communication with satellites in an NTN. For example, network  100  may be an NTN. 
     Although  FIG. 1  illustrates one example of a wireless network, various changes may be made to  FIG. 1 . For example, the wireless network could include any number of BSs and any number of UEs in any suitable arrangement. Also, the BS  101  could communicate directly with any number of UEs and provide those UEs with wireless broadband access to the network  130 . Similarly, each BS  102 - 103  could communicate directly with the network  130  and provide UEs with direct wireless broadband access to the network  130 . Further, the BSs  101 ,  102 , and/or  103  could provide access to other or additional external networks, such as external telephone networks or other types of data networks. 
       FIG. 2  illustrates an example BS  102  according to embodiments of the present disclosure. The embodiment of the BS  102  illustrated in  FIG. 2  is for illustration only, and the BSs  101  and  103  of  FIG. 1  could have the same or similar configuration. However, BSs come in a wide variety of configurations, and  FIG. 2  does not limit the scope of this disclosure to any particular implementation of a BS. 
     As shown in  FIG. 2 , the BS  102  includes multiple antennas  205   a - 205   n , multiple radio frequency (RF) transceivers  210   a - 210   n , transmit (TX) processing circuitry  215 , and receive (RX) processing circuitry  220 . The BS  102  also includes a controller/processor  225 , a memory  230 , and a backhaul or network interface  235 . 
     The RF transceivers  210   a - 210   n  receive, from the antennas  205   a - 205   n , incoming RF signals, such as signals transmitted by UEs in the wireless network  100 . The RF transceivers  210   a - 210   n  down-convert the incoming RF signals to generate IF or baseband signals. The IF or baseband signals are sent to the RX processing circuitry  220 , which generates processed baseband signals by filtering, decoding, and/or digitizing the baseband or IF signals. The RX processing circuitry  220  transmits the processed baseband signals to the controller/processor  225  for further processing. 
     The TX processing circuitry  215  receives analog or digital data (such as voice data, web data, e-mail, or interactive video game data) from the controller/processor  225 . The TX processing circuitry  215  encodes, multiplexes, and/or digitizes the outgoing baseband data to generate processed baseband or IF signals. The RF transceivers  210   a - 210   n  receive the outgoing processed baseband or IF signals from the TX processing circuitry  215  and up-converts the baseband or IF signals to RF signals that are transmitted via the antennas  205   a - 205   n.    
     The controller/processor  225  can include one or more processors or other processing devices that control the overall operation of the BS  102 . For example, the controller/processor  225  could control the reception of UL channel signals and the transmission of DL channel signals by the RF transceivers  210   a - 210   n , the RX processing circuitry  220 , and the TX processing circuitry  215  in accordance with well-known principles. The controller/processor  225  could support additional functions as well, such as more advanced wireless communication functions. For instance, the controller/processor  225  could support uplink transmission timing in NTNs. Any of a wide variety of other functions could be supported in the BS  102  by the controller/processor  225 . In some embodiments, the controller/processor  225  includes at least one microprocessor or microcontroller. 
     The controller/processor  225  is also capable of executing programs and other processes resident in the memory  230 , such as an OS. The controller/processor  225  can move data into or out of the memory  230  as required by an executing process. In certain embodiments, the controller/processor  225  supports uplink transmission timing in NTNs. For example, the controller/processor  225  can move data into or out of the memory  230  according to a process that is being executed. 
     The controller/processor  225  is also coupled to the backhaul or network interface  235 . The backhaul or network interface  235  allows the BS  102  to communicate with other devices or systems over a backhaul connection or over a network. The network interface  235  could support communications over any suitable wired or wireless connection(s). For example, when the BS  102  is implemented as part of a cellular communication system (such as one supporting 5G/NR, LTE, or LTE-A), the network interface  235  could allow the BS  102  to communicate with other BSs over a wired or wireless backhaul connection. When the BS  102  is implemented as an access point, the network interface  235  could allow the BS  102  to communicate over a wired or wireless local area network or over a wired or wireless connection to a larger network (such as the Internet). The network interface  235  includes any suitable structure supporting communications over a wired or wireless connection, such as an Ethernet or RF transceiver. 
     The memory  230  is coupled to the controller/processor  225 . Part of the memory  230  could include a RAM, and another part of the memory  230  could include a Flash memory or other ROM. 
     Although  FIG. 2  illustrates one example of BS  102 , various changes may be made to  FIG. 2 . For example, the BS  102  could include any number of each component shown in  FIG. 2 . As a particular example, an access point could include a number of network interfaces  235 , and the controller/processor  225  could support routing functions to route data between different network addresses. As another particular example, while shown as including a single instance of TX processing circuitry  215  and a single instance of RX processing circuitry  220 , the BS  102  could include multiple instances of each (such as one per RF transceiver). Also, various components in  FIG. 2  could be combined, further subdivided, or omitted and additional components could be added according to particular needs. 
       FIG. 3  illustrates an example UE  116  according to embodiments of the present disclosure. The embodiment of the UE  116  illustrated in  FIG. 3  is for illustration only, and the UEs  111 - 115  of  FIG. 1  could have the same or similar configuration. However, UEs come in a wide variety of configurations, and  FIG. 3  does not limit the scope of this disclosure to any particular implementation of a UE. 
     As shown in  FIG. 3 , the UE  116  includes an antenna  305 , a RF transceiver  310 , TX processing circuitry  315 , a microphone  320 , and receive (RX) processing circuitry  325 . The UE  116  also includes a speaker  330 , a processor  340 , an input/output (I/O) interface (IF)  345 , an input device  350 , a display  355 , and a memory  360 . The memory  360  includes an operating system (OS)  361  and one or more applications  362 . 
     The RF transceiver  310  receives, from the antenna  305 , an incoming RF signal transmitted by a BS of the wireless network  100 . The RF transceiver  310  down-converts the incoming RF signal to generate an intermediate frequency (IF) or baseband signal. The IF or baseband signal is sent to the RX processing circuitry  325  that generates a processed baseband signal by filtering, decoding, and/or digitizing the baseband or IF signal. The RX processing circuitry  325  transmits the processed baseband signal to the speaker  330  (such as for voice data) or to the processor  340  for further processing (such as for web browsing data). 
     The TX processing circuitry  315  receives analog or digital voice data from the microphone  320  or other outgoing baseband data (such as web data, e-mail, or interactive video game data) from the processor  340 . The TX processing circuitry  315  encodes, multiplexes, and/or digitizes the outgoing baseband data to generate a processed baseband or IF signal. The RF transceiver  310  receives the outgoing processed baseband or IF signal from the TX processing circuitry  315  and up-converts the baseband or IF signal to an RF signal that is transmitted via the antenna  305 . 
     The processor  340  can include one or more processors or other processing devices and execute the OS  361  stored in the memory  360  in order to control the overall operation of the UE  116 . For example, the processor  340  could control the reception of DL channel signals and the transmission of UL channel signals by the RF transceiver  310 , the RX processing circuitry  325 , and the TX processing circuitry  315  in accordance with well-known principles. In some embodiments, the processor  340  includes at least one microprocessor or microcontroller. 
     The processor  340  is also capable of executing other processes and programs resident in the memory  360 , such as processes for beam management. The processor  340  can move data into or out of the memory  360  as required by an executing process. In some embodiments, the processor  340  is configured to execute the applications  362  based on the OS  361  or in response to signals received from BSs or an operator. The processor  340  is also coupled to the I/O interface  345 , which provides the UE  116  with the ability to connect to other devices, such as laptop computers and handheld computers. The I/O interface  345  is the communication path between these accessories and the processor  340 . 
     The processor  340  is also coupled to the input device  350 . The operator of the UE  116  can use the input device  350  to enter data into the UE  116 . The input device  350  can be a keyboard, touchscreen, mouse, track ball, voice input, or other device capable of acting as a user interface to allow a user in interact with the UE  116 . For example, the input device  350  can include voice recognition processing, thereby allowing a user to input a voice command. In another example, the input device  350  can include a touch panel, a (digital) pen sensor, a key, or an ultrasonic input device. The touch panel can recognize, for example, a touch input in at least one scheme, such as a capacitive scheme, a pressure sensitive scheme, an infrared scheme, or an ultrasonic scheme. 
     The processor  340  is also coupled to the display  355 . The display  355  may be a liquid crystal display, light emitting diode display, or other display capable of rendering text and/or at least limited graphics, such as from web sites. 
     The memory  360  is coupled to the processor  340 . Part of the memory  360  could include a random access memory (RAM), and another part of the memory  360  could include a Flash memory or other read-only memory (ROM). 
     Although  FIG. 3  illustrates one example of UE  116 , various changes may be made to  FIG. 3 . For example, various components in  FIG. 3  could be combined, further subdivided, or omitted and additional components could be added according to particular needs. As a particular example, the processor  340  could be divided into multiple processors, such as one or more central processing units (CPUs) and one or more graphics processing units (GPUs). Also, while  FIG. 3  illustrates the UE  116  configured as a mobile telephone or smartphone, UEs could be configured to operate as other types of mobile or stationary devices. 
       FIG. 4  and  FIG. 5  illustrate example wireless transmit and receive paths according to this disclosure. In the following description, a transmit path  400 , of  FIG. 4 , may be described as being implemented in a BS (such as the BS  102 ), while a receive path  500 , of  FIG. 5 , may be described as being implemented in a UE (such as a UE  116 ). However, it may be understood that the receive path  500  can be implemented in a BS and that the transmit path  400  can be implemented in a UE. In some embodiments, the receive path  500  is configured to support uplink transmission timing in NTNs as described in embodiments of the present disclosure. 
     The transmit path  400  as illustrated in  FIG. 4  includes a channel coding and modulation block  405 , a serial-to-parallel (S-to-P) block  410 , a size N inverse fast Fourier transform (IFFT) block  415 , a parallel-to-serial (P-to-S) block  420 , an add cyclic prefix block  425 , and an up-converter (UC)  430 . The receive path  500  as illustrated in  FIG. 5  includes a down-converter (DC)  555 , a remove cyclic prefix block  560 , a serial-to-parallel (S-to-P) block  565 , a size N fast Fourier transform (FFT) block  570 , a parallel-to-serial (P-to-S) block  575 , and a channel decoding and demodulation block  580 . 
     As illustrated in  FIG. 4 , the channel coding and modulation block  405  receives a set of information bits, applies coding (such as a low-density parity check (LDPC) coding), and modulates the input bits (such as with quadrature phase shift keying (QPSK) or quadrature amplitude modulation (QAM)) to generate a sequence of frequency-domain modulation symbols. The serial-to-parallel block  410  converts (such as de-multiplexes) the serial modulated symbols to parallel data in order to generate N parallel symbol streams, where N is the IFFT/FFT size used in the BS  102  and the UE  116 . The size N IFFT block  415  performs an IFFT operation on the N parallel symbol streams to generate time-domain output signals. The parallel-to-serial block  420  converts (such as multiplexes) the parallel time-domain output symbols from the size N IFFT block  415  in order to generate a serial time-domain signal. The add cyclic prefix block  425  inserts a cyclic prefix to the time-domain signal. The up-converter  430  modulates (such as up-converts) the output of the add cyclic prefix block  425  to an RF frequency for transmission via a wireless channel. The signal may also be filtered at baseband before conversion to the RF frequency. 
     A transmitted RF signal from the BS  102  arrives at the UE  116  after passing through the wireless channel, and reverse operations to those at the BS  102  are performed at the UE  116 . 
     As illustrated in  FIG. 5 , the down-converter  555  down-converts the received signal to a baseband frequency, and the remove cyclic prefix block  560  removes the cyclic prefix to generate a serial time-domain baseband signal. The serial-to-parallel block  565  converts the time-domain baseband signal to parallel time domain signals. The size N FFT block  570  performs an FFT algorithm to generate N parallel frequency-domain signals. The parallel-to-serial block  575  converts the parallel frequency-domain signals to a sequence of modulated data symbols. The channel decoding and demodulation block  580  demodulates and decodes the modulated symbols to recover the original input data stream. 
     Each of the BSs  101 - 103  may implement a transmit path  400  as illustrated in  FIG. 4  that is analogous to transmitting in the downlink to UEs  111 - 116  and may implement a receive path  500  as illustrated in  FIG. 5  that is analogous to receiving in the uplink from UEs  111 - 116 . Similarly, each of UEs  111 - 116  may implement the transmit path  400  for transmitting in the uplink to the BSs  101 - 103  and may implement the receive path  500  for receiving in the downlink from the BSs  101 - 103 . 
     Each of the components in  FIG. 4  and  FIG. 5  can be implemented using hardware or using a combination of hardware and software/firmware. As a particular example, at least some of the components in  FIG. 4  and  FIG. 5  may be implemented in software, while other components may be implemented by configurable hardware or a mixture of software and configurable hardware. For instance, the FFT block  570  and the IFFT block  515  may be implemented as configurable software algorithms, where the value of size N may be modified according to the implementation. 
     Furthermore, although described as using FFT and IFFT, this is by way of illustration only and may not be construed to limit the scope of this disclosure. Other types of transforms, such as discrete Fourier transform (DFT) and inverse discrete Fourier transform (IDFT) functions, can be used. It may be appreciated that the value of the variable N may be any integer number (such as 1, 2, 3, 4, or the like) for DFT and IDFT functions, while the value of the variable N may be any integer number that is a power of two (such as 1, 2, 4, 8, 16, or the like) for FFT and IFFT functions. 
     Although  FIG. 4  and  FIG. 5  illustrate examples of wireless transmit and receive paths, various changes may be made to  FIG. 4  and  FIG. 5 . For example, various components in  FIG. 4  and  FIG. 5  can be combined, further subdivided, or omitted and additional components can be added according to particular needs. Also,  FIG. 4  and  FIG. 5  are meant to illustrate examples of the types of transmit and receive paths that can be used in a wireless network. Any other suitable architectures can be used to support wireless communications in a wireless network. 
     Embodiments of the present disclosure relate to a determination of the timing offset for transmission of uplink channels in a NTN. The present disclosure also relates to requesting a timing offset by a UE for timing advance (TA) validation for transmission in preconfigured uplink resources. The present disclosure further relates to a transmission with preconfigured uplink resources and the transmission of uplink resources scheduled by a downlink control information (DCI) format in multi-beam NTNs. Additionally, the present disclosure relates a determination of the timing offset for transmission of an uplink data channel and physical random access channel (PRACH) preamble transmission initiated by a physical downlink control channel (PDCCH) order in NTNs. Embodiments of the present disclosure also relate to a reporting of a timing offset during initial access. Embodiments of the present disclosure further relate to determining a timing offset by a higher layer configuration and a medium access control coverage enhancement (MAC-CE) indication in connected mode. 
     The terms gNB or BS as used throughout this disclosure describe a base station which can be part of an LTE-based or NR-based network. Embodiments described in this disclosure for either NB-internet of things (IoT) or LTE enhanced machine type communication (eMTC) operating in an NTN apply to both of these LTE-based technologies and also to an NR-based NTN. 
     An NTN is a network using RF resources on board a satellite or an unmanned aerial service (UAS) platform, and includes satellite which can be a Geostationary Earth Orbiting (GEO) satellite served by one or several sat-gateways which are deployed across the satellite targeted coverage or a non-GEO satellite served successively by one or several satellite-gateways at a time, a radio link between a sat-gateway and the satellite or UAS platform, a radio link between the UE and the satellite or UAS platform. A satellite or UAS platform may implement either a transparent or a regenerative (with on board processing) payload. The satellite or UAS platform typically generates several beams over a given service area bounded by its field of view which depends on the on board antenna diagram and elevation angle. The footprint of a beam has an elliptic shape and is considered as a cell in terrestrial networks. 
     The propagation delays in NTN are much longer than the propagation delays in terrestrial mobile systems which are usually less than 1 ms, ranging from several milliseconds to hundreds of milliseconds depending on the altitudes of the spaceborne or airborne platforms and payload type in NTN. The cell size in NTN is much larger and UE in different parts of the cell experience different delays. Thus, the long propagation delays and large cell size require modifications of the timing aspects defined in terrestrial networks both at the physical layer and higher layers, including the TA mechanism. 
     A TA is an offset applied by the UE to an uplink transmission to ensure that the downlink and uplink frames are synchronized at the base station. A gNB can measure the timing of uplink signal from each UE and adjust the uplink transmission timing by sending the value of TA to the respective UE. When a UE sends a transmission, e.g. PRACH, physical uplink shared channel (PUSCH), physical uplink control channel (PUCCH), sounding reference signal (SRS), the gNB can estimate the uplink signal arrival time which can then be used to calculate the required TA value. The gNB can estimate the initial TA from PRACH sent by the UE and send a TA signaling in Random Access Response (RAR). Once the UE is in connected mode, the gNB estimates the TA value and, if a correction is needed, sends it to the UE by MAC Control Element. A gNB can also send a same TA value to all UEs in a cell. The TA value can be the maximum value among the values needed to adjust the TA of each UE in a cell. 
     Rel-16 NB-IoT and LTE-MTC support transmission in preconfigured uplink resources where a UE can transmit resources that were preassigned before connection setup. The main motivation for transmitting in preconfigured resources is to reduce the overhead of the signaling Msg1 through Msg4 at connection set up assuming the UE has obtained a valid TA. A UE (such as the UE  116 ) is configured with preconfigured uplink resources via dedicated RRC signaling while in connected state and obtains time-frequency resources, a preconfigured uplink resource (PUR) cell radio network temporary identifier (C-RNTI), power control parameters, and other parameters. The TA validation can be based on a timer which is part of the resource configuration or on a difference in reference signal received power (RSRP) values from the time that the configuration was done compared to a configured threshold. When a preconfigured uplink resources transmission is successfully received by the eNB, the acknowledgment can be provided in a DCI or in in an RRC message. After a time offset from when the transmission ends, the UE monitors a DCI format scrambled by the PUR C-RNTI that includes an acknowledgment or a retransmission request in a search space window of configurable length. 
     For early data transmission (EDT), Msg1 and Msg2 are used for TA validation and then data transmission starts in Msg3 that contains an RRC message. Msg4 acknowledges the UL data transmission and moves the UE to connected state. A Li in idle mode can transmit data in Msg3 of the random access procedure, and after successful reception by eNB, the random access procedure terminates and the UE does not transition to connected mode unless the MME or the eNB decides to move the UE to connected mode. The UE can request a grant for Early data Transmission (EDT) if the amount of pending data is smaller than a maximum size configured by eNB, by using a pre-configured set of narrowband physical random access channel (NPRACH) resources for preamble transmission. The eNB can allow the UE to transmit an amount of data smaller than the maximum configured size, and as needed, the eNB can order fallback to legacy random-access procedure during the EDT procedure. 
     For transmission in preconfigured resources for TA validation a UE can use a timing offset that was received for example in system information block (SIB). The timing offset in SIB can be a cell specific offset that the gNB configures for all UEs in a same cell. In large NTN cells configuring a single timing offset for all UEs can be not accurate because of the large variation of the transmission delays among the UEs. Thus there is a need to determine a more accurate timing offset to apply for TA validation for transmission in preconfigured uplink resources. The need of an accurate time offset in large NTN cells also exist for transmission of channels other than the data channel and for transmission modes other than preconfigured resources, for example for scheduled data transmission in connected mode or for transmission of uplink messages during initial access. 
     Throughout the disclosure, embodiments for requesting a timing offset or determining a timing offset by a UE for TA validation for uplink transmission in NTN are described for transmission in preconfigured uplink resources and equally apply to transmission in non-preconfigured resources wherein an uplink transmission is scheduled by a DCI format. 
     Additionally, throughout the disclosure, the terms Timing Advance, timing offset, and timing adjustment are interchangeably used. 
     Moreover, throughout the disclosure, embodiments are described for NB-IoT and equally apply to LTE-MTC and NR. Timing offsets described for uplink transmissions of NB-IoT channels such NPRACH or narrowband physical uplink shard channel (NPUSCH) and related to the reception of downlink channels such as narrowband physical downlink control channel (NPDCCH) or narrowband physical downlink shared channel (NPDSCH), equally apply to MPRACH, MPUSCH, MPDCH, MPDSCH for LTE-MTC and to PRACH, PUSCH, PDCCH and PDSCH in NR. 
     Furthermore, the terms BS, eNB, and gNB are interchangeably used throughout the disclosure. 
     For transmission in preconfigured uplink resources, a validation of the timing offset is done by the UE before starting transmission in the preconfigured resources. A UE (such as the UE  116 ) sends a PURConfigurationRequest message to indicate to the gNB that the UE is interested to be configured with preconfigured uplink resources and to provide preconfigured uplink resources related information to gNB, including the requested time gap from the transmission of the request of preconfigured uplink resources until the first transmission occasion. A gNB indicates the time gap with respect to current time until the first transmission occasion in the configuration. When a UE is configured with preconfigured resources, the UE can be already in possess of a timing offset, for example the timing offset received in SIB and common to all users in the cell. For validation of the TA before transmitting in the preconfigured resources, the UE can use the timing offset received in SIB and/or received in the preconfigured resources configuration, wherein the timing offset is always present in the preconfigured uplink resources configuration in NTN. A gNB can also indicate in SIB whether the timing offset in SIB can be used for TA validation prior to transmission in preconfigured resources. A gNB can configure a criterion for TA validation in SIB and indicate whether the timing offset provided in SIB can be used for TA validation with a configured TA validation criterion. 
       FIG. 6  illustrates a method  600  for a UE to determine a timing offset transmission of preconfigured uplink resources according to embodiments of present disclosure. In particular, the method  600  describes a UE (such as the UE  116 ) determining a timing offset transmission of preconfigured uplink resources by requesting a timing offset and receiving it in the configuration of the preconfigured resources.  FIG. 7  illustrates a method  700  for a UE to request a timing offset to adapt the transmission of preconfigured recourses that were previously configured to the UE according to embodiments of present disclosure.  FIG. 8  illustrates a method  800  for a UE to update a timing offset applied to uplink transmission after coverage is obtained from a different beam of the same or different satellite or unmanned aircraft system (UAS) platform according to embodiments of present disclosure. 
     The steps of the methods  600 ,  7000 , and  800  can be performed by any of the UEs  111 - 116  of  FIG. 1 , such as the UE  116  of  FIG. 3 , as well as any of the BSs  101 - 103  of  FIG. 1 , such as the BS  102  of  FIG. 2 . The method  600  of  FIG. 6 , method  700  of  FIG. 7 , and method  800  of  FIG. 8  are for illustration only and other embodiments can be used without departing from the scope of the present disclosure. 
     As illustrated in  FIG. 6 , the method  600  describes a UE determining a timing offset for transmission of preconfigured uplink resources by requesting a timing offset and receiving it in the configuration of the preconfigured resources. 
     In step  610 , a UE (such as the UE  116 ) is provided a first time offset to adjust the transmission timing respect to the time when the DL signal carrying such information is received at the UE in step  620 , the UE sends a request to be configured with preconfigured resources and sends a requested time offset. In step  630 , the UE is configured for transmission with preconfigured uplink resources, wherein the configuration includes a second time offset. In step  640 , the UE uses the second time offset to validate a TA with an indicated criterion for TA validation, wherein the criterion can be based on a threshold of an RSRP. Upon validation of the TA, the UE in step  650 , transmits in the preconfigured uplink resources. 
     A UE (such as the UE  116 ) with Global Navigation Satellite System (GNSS) capability can estimate and pre-compensate a timing offset with sufficient accuracy for uplink (UL) transmission, and utilize the estimated timing offset in determining the transmission time of an uplink channel in preconfigured or scheduled uplink resources. A UE can also utilize such estimated timing offset as a requested timing offset sent in the resource configuration request in step  620  in  FIG. 6 , wherein the timing offset is received by a gNB that provides a second timing offset in step  630 . 
     In certain embodiments, a UE (such as the UE  116 ) validates a TA and starts transmitting in the preconfigured uplink resources. The validity of the TA can be associated to a timer which was provided in the preconfigured resources configuration, wherein the timer can be given in number of subframes or slots after the first transmission in the configured preconfigured resources. If the timer expires while there are still resources assigned to the UE, and the UE desires to keep the resources, the TA needs to be validated again. The UE can send a request to the gNB to update the TA including a requested time offset from the transmission of such request until the next resource transmission occasion after the last resource that was utilized by a UE and received by a gNB. The gNB will configure a new timing offset. The request by the UE is done by RRC signaling and the UE send the request after sending a PRACH and receiving a RAR. 
     As illustrated in  FIG. 7 , the method  700  describes a UE requesting a timing offset to adapt the transmission of preconfigured resources that were already configured to the UE. 
     In step  710 , a UE (such as the UE  116 ) is provided preconfigured uplink resources configuration by a gNB and transmits in a number of preconfigured resources occasions. In step  720 , the UE send a request to be configured a time offset including a requested time offset. In step  730 , the UE receives a time offset and validates a TA before transmitting in a preconfigured resource occasion. 
     Alternatively, the TA validation prior to transmitting in the preconfigured resources can be done by transmitting a PRACH and receiving a timing offset information in the RAR. This can be done for TA validation before the initial transmission in the preconfigured resources and/or TA validation for transmission in any of the transmission occasions when the TA is considered invalid by the UE. 
     In Rel-16 NB-IoT and eMTC operation in terrestrial networks, a serving cell change enables a TA validation. The TA is considered invalid when the UE initiates the RA procedure in a different cell than where TA was last validated. In NTN, downlinks are being used to achieve efficient coverage and different beam footprints can be seen as different cells in terrestrial networks. The different beams can correspond to a single or multiple satellites or UAS platforms. Thus, a serving beam change in NTN enables a TA validation. 
     As illustrated in  FIG. 8 , the method  800  describes a UE updating a timing offset applied to uplink transmissions after coverage is obtained from a different beam of a same or different satellite or UAS platform. 
     In step  810 , a UE (such as the UE  116 ) has coverage from a first DL beam and determines the timing of an uplink transmission from a time offset acquired while served by the first beam. In step  820 , the UE changes serving beam to a second beam. In step  830 , the UE acquires a new time offset, wherein the new time offset can be configured in SIB or provided during or after the initial access procedure. 
     Although  FIGS. 6-8  illustrate the methods  600 - 800  various changes may be made to  FIGS. 6-8 . For example, while the methods  600 - 800  are shown as a series of steps, various steps could overlap, occur in parallel, occur in a different order, or occur multiple times. In another example, steps may be omitted or replaced by other steps. For example, steps of the method  600  can be executed in a different order. 
     Embodiments of the present disclosure describe refining the timing for transmission an uplink channel after initial access. The following examples and embodiments, such as those of  FIGS. 9-12  describe this in greater detail. 
       FIG. 9  illustrates a method  900  for a UE to determine a transmission time during initial access and in connected mode according to embodiments of present disclosure.  FIG. 10  illustrates a method  1000  for a UE to determine a transmission timing from a cell-specific timing offset indicated by a gNB and an estimated UE-specific timing offset according to embodiments of present disclosure.  FIG. 11  illustrates a method  1100  for when a UE uses a first timing offset provided by a RAR during initial access and uses a second timing offset during connected mode, where the second timing offset is based on a UE report and a gNB indication according to embodiments of present disclosure.  FIG. 12  illustrates a method  1200  for when a UE uses a first timing offset provided by a RAR during initial access and uses a second timing offset during connected mode, where the second timing offset is based on a UE reporting Msg3 and a gNB indication according to embodiments of present disclosure. 
     The steps of the methods  900 ,  1000 ,  1100 , and  1200  can be performed by any of the UEs  111 - 116  of  FIG. 1 , such as the UE  116  of  FIG. 3 , as well as any of the BSs  101 - 103  of  FIG. 1 , such as the BS  102  of  FIG. 2 . The method  900  of  FIG. 9 , method  1000  of  FIG. 10 , method  1100  of  FIG. 11 , and method  1200  of  FIG. 12  are for illustration only and other embodiments can be used without departing from the scope of the present disclosure. 
     In certain embodiments, a timing offset applied by a UE (such as the UE  116 ) for an uplink transmission is refined for transmission after initial access. In NTN, the determination of the timing offset to use in the timing relationships of uplink channels can be done by using one or more values of the timing offset. For example, one value is provided in SIB for transmission during initial access, and refining the timing offset value is in connected mode, wherein the timing offset can be provided by a DCI format or RRC signaling or MAC-CE signaling. 
     As illustrated in  FIG. 9 , the method  900  describes an example of a UE determining a transmission time during initial access and in connected mode. 
     In step  910 , a UE (such as the UE  116 ) is configured a first value of a timing offset by a gNB in SIB. In step  920 , the UE transmits Msg3 PUSCH with a transmission time derived from the first timing offset. In step  930 , the UE transmits uplink channels with transmission times derived from a second value of the timing offset provided by a DCI format or RRC signaling. Alternatively, in step  930  transmission times are derived from a combination of the first and second values of the timing offset. Alternatively, or additionally, in step  930  a timing offset can be provided by MAC-CE signaling. 
     In certain embodiments, a timing offset applied by a UE (such as the UE  116 ) for an uplink transmission is refined for transmission during or after initial access based on an estimated timing offset by the UE when the UE receives an indication that enables the report of the estimated timing offset. A UE can receive a timing offset in a RAR, wherein the timing offset is a cell-specific value, and transmit Msg3 PUSCH with a transmission time derived from the received timing offset in the RAR and from an estimated timing offset wherein the estimated timing offset is a UE-specific value. The UE transmits the estimated timing offset value in Msg3 PUSCH by MAC-CE signaling so that the gNB can estimate a UE-specific timing offset value that would be indicated in Msg4. 
     As illustrated in  FIG. 10 , the method  1000  describes a UE determining a transmission timing from a cell-specific timing offset indicated by a gNB and an estimated UE-specific timing offset. 
     In step  1010 , a UE (such as the UE  116 ) receives a first timing offset in a RAR. In step  1020 , the UE estimates a UE-specific second timing offset and determines a third timing offset for Msg3 PUSCH transmission from the first timing offset and the estimated UE-specific second timing offset. In step  1030 , the UE transmits Msg3 PUSCH using the third timing offset and reports the second timing offset in Msg3 PUSCH. In step  1040 , the UE receives a fourth timing offset in Msg4. 
     In certain embodiments, it is possible that in step  1030 , the UE determines an offset timing for Msg3 transmission from the first timing offset and transmits Msg3 PUSCH with the determined first timing offset. The estimated UE-specific second timing offset is reported in Msg3 PUSCH but it is not used in the determination of the timing offset used for the Msg3 PUSCH transmission. This avoids a misunderstanding between the UE and the network about the timing offset used for the transmission of Msg3 PUSCH wherein the latter would depend only on the offset indicated by the network. 
     In certain embodiments, the UE reports an estimated timing offset after receiving Msg4, wherein the estimated timing offset is used by the gNB to calculate an offset signaled to the UE by a Timing Advance Command in MAC CE in an RRC configuration. 
     The timing offset used by the UE for Msg3 transmission or for an uplink transmission upon reception of Msg4 or for an uplink transmission during connected mode can be based on a combination of DCI signaling, Timing Advance Command in MAC CE and RRC configuration, or a combination of Timing Advance Command in MAC CE and RRC configuration, or during initial access of a combination of Timing Advance Command in RAR and RRC configuration. 
     The Timing Advance Command in RAR has 11 bits and can indicate an index value TA (0, 1, 2 . . . 1282). The index value TA is used to control the amount of timing adjustment that UE has to apply. The amount of the time alignment is given by NTA=TA×16. The Timing Advance obtained via RAR is always positive with a minimum adjustment when TA=1 and maximum adjustment when TA=1282. To cover the large distance in NTN, the field that indicates the offset in RAR needs to be extended above 11 bits, or the Timing Advance calculation is scaled differently and the timing adjustment in NTN will have a different granularity than the granularity of the timing adjustment in terrestrial networks. 
     The Timing Advance Command in MAC CE indicates relative Timing Advance which is 6-bit index value T A  (0, 1, 2 . . . 63). In this case, N TA,new =N TA,old +(T A −31)×16 where N TA,old  is the current timing adjustment and N TA,new  indicates new value. To cover the large distance in NTN, the field that indicates the offset in MAC CE needs to be extended above 6 bits, or the Timing Advance calculation is scaled differently and the timing adjustment in NTN will have a different granularity than the granularity of the timing adjustment in terrestrial networks. 
     In certain embodiments a UE (such as UE  116 ) uses a cell-specific timing offset provided by a gNB (such as BS  102 ) during initial access and is configured to use a UE-specific timing offset in connected mode. A UE can be configured to report a timing offset during initial access, for example in Msg3, or in Msg5 or during connected mode wherein a gNB can trigger a UE report by a DCI format. 
     As illustrated in  FIG. 11 , the method  1100  describes an example when the UE uses a first timing offset provided by a RAR during initial access and uses a second timing offset during connected mode, wherein the second timing offset is based on a UE report and a gNB indication. 
     In step  1110 , a UE (such as the UE  116 ) is configured to report a timing offset after reception of Msg4, in step  1120 , the UE receives a first timing offset in RAR, wherein the first timing offset is applied to a Msg3 PUSCH transmission. In step  1130 , the UE reports an estimated timing offset in a Msg5, wherein the Msg5 is transmitted applying the first timing offset. In step  1140 , the UE receives a second timing offset after transmission of Msg5, wherein the second timing offset is indicated in MAC-CE. Alternatively, in step  1140 , the second timing offset is configured by an RRC parameter or is indicated in a DCI format or a combination of the above. 
     As illustrated in  FIG. 12 , the method  1200  describes an example when the UE uses a first timing offset provided by a RAR during initial access and uses a second timing offset during connected mode, wherein the second timing offset is based on a UE report in Msg3 and a gNB indication. 
     In step  1210 , a UE (such as the UE  116 ) is configured to report a timing offset in Msg3 PUSCH. In step  1220 , the UE receives a first timing offset in RAR. In step  1230 , the UE reports an estimated timing offset in Msg3 PUSCH, wherein the Msg3 PUSCH is transmitted using the first timing offset. In step  1240 , the UE receives a second timing offset, wherein the second timing offset is indicated by MAC-CE signaling. 
     Although  FIGS. 9-12  illustrate the methods  900 - 1200  various changes may be made to  FIGS. 9-12 . For example, while the methods  900 - 1200  are shown as a series of steps, various steps could overlap, occur in parallel, occur in a different order, or occur multiple times. In another example, steps may be omitted or replaced by other steps. For example, steps of the method  900  can be executed in a different order. 
     Embodiments of the present disclosure also describe determining timing for transmission of an uplink channel or the timing for monitoring of a downlink channel. The following examples and embodiments, such as those of  FIG. 13  describe this in greater detail. 
       FIG. 13  illustrates a method  1300  for when a UE uses a first timing offset provided by a RAR during initial access and uses a second timing offset during connected mode, where the second timing offset is based on a UE report and a gNB indication according to embodiments of present disclosure. The steps of the method  1300  can be performed by any of the UEs  111 - 116  of  FIG. 1 , such as the UE  116  of  FIG. 3 , as well as any of the BSs  101 - 103  of  FIG. 1 , such as the BS  102  of  FIG. 2 . The method  1300  of  FIG. 13  is for illustration only and other embodiments can be used without departing from the scope of the present disclosure. 
     The propagation delays in NTN are much longer than the propagation delays in terrestrial mobile systems which are usually less than 1 ms, ranging from several milliseconds to hundreds of milliseconds depending on the altitudes of the airborne platforms. The cell size in NTN is much larger and UEs in different parts of the cell experience different delays. Thus, for NTN there is a need to take into account the long propagation delays and large cell size in the timing relationships between DL and UL channels in order to align DL and UL receptions at the eNB side. A timing offset k_offset needs to be considered in the timing relationships for transmission by the UE. The timing offset k_offset needs also to be considered in the timing relationships for monitoring DL channels by the UE. 
     In certain embodiments, a timing offset k_offset is derived from a timing information provided in SIB, or configured in a preconfigured resource configuration, or configured in a timing offset configuration, or provided by a Timing Advance Command in a RAR or by Timing Advance Command in MAC CE. The value of k_offset can be in subframe unit or slot unit. 
     When a UE (such as the UE  116 ) is configured for PUR transmission by higher layers, the UE decodes NPDCCH with CRC scrambled by the PUR-RNTI and the corresponding NPDSCH. If the UE has initiated a NPUSCH transmission using preconfigured uplink resource ending in subframe n, the UE shall monitor the NPDCCH UE-specific search space in a search space window starting in subframe n+x with duration given by higher layer parameter pur-SS-window-duration. The value of x can be x=m+k wherein the value of m can be a fixed value, for example m=4, or can be provided by higher layer. The value of the parameters n, m and k can be in subframe unit or slot unit. The value of the parameter m can be any integer number, including 0. It is also possible that the parameter m can have a negative value to indicate early ending of the NPUSCH transmission using preconfigured uplink resource and start of monitoring the NPDCCH UE-specific search space. The value of the parameter k can be equal to the value of a round trip time (RTT) between a UE and a gNB, wherein the RTT value is given by the sum of a TA value and an additional value k MAC , if present, provided by higher layers. Then the UE shall monitor the NPDCCH UE-specific search space in a search space window starting in subframe n+m+TA+k MAC  It is also possible that the value of the parameter k is equal to the value of k MAC  provided by higher layers. Then the UE shall monitor the NPDCCH UE-specific search space in a search space window starting in subframe n+m+k MAC . 
     As illustrated in  FIG. 13 , the method  1300  describes an example when the UE uses a first timing offset provided by a RAR during initial access and uses a second timing offset during connected mode, wherein the second timing offset is based on a UE report and a gNB indication. 
     In step  1310 , a UE (such as the UE  116 ) is configured for PUR transmission by higher layers. In step  1320 , the UE is provided by higher layer parameter pur-SS-window-duration a duration of a monitoring window. In step  1330 , the UE transmits a NPUSCH transmission using preconfigured uplink resource ending in subframe n. In step  1340 , the UE monitors the NPDCCH UE-specific search space in a search space window starting in subframe n+d, wherein d is given by one or by the sum of two or more of the following quantities: a first fixed timing offset, a second configured timing offset, a third value depending on the RTT wherein the third value is the sum of a Timing Advance (TA) and an additional k MAC  value provided by higher layer. 
     Although  FIG. 13  illustrates the method  1300  various changes may be made to  FIG. 13 . For example, while the method  1300  is shown as a series of steps, various steps could overlap, occur in parallel, occur in a different order, or occur multiple times. In another example, steps may be omitted or replaced by other steps. For example, steps of the method  1300  can be executed in a different order. 
     Embodiments of the present disclosure also describe determining a timing relationship of a DCI format zero to NPUSCH format 1. 
     In certain embodiments, a timing offset is associated to the transmission of a NPUSCH format 1 scheduled by a DCI format 0 in NTN. NPUSCH format 1 transmission can be scheduled by a NPDCCH with DCI format NO, or the transmission can correspond to using preconfigured uplink resource configured by higher layers. Transmission using preconfigured uplink resource is initiated by higher layers, while retransmission of transport blocks transmitted using preconfigured uplink resource are scheduled by a NPDCCH with DCI format NO. 
     A UE shall upon detection on a given serving cell of a NPDCCH with DCI format NO ending in NB-IoT DL subframe n scheduling NPUSCH intended for the UE, perform, at the end of either (i) n+k 0 +k_offset DL subframe for frequency division duplex (FDD), or (ii) k 0 +k_offset NB-IoT UL subframes following the end of n+8 subframe for time division duplex (TDD), a corresponding NPUSCH transmission using NPUSCH format 1 in N consecutive NB-IoT UL slots n i  with i=0, 1, . . . , N−1 according to the NPDCCH information. Here, the subframe n is the last subframe in which the NPDCCH is transmitted and is determined from the starting subframe of NPDCCH transmission and the DCI subframe repetition number field in the corresponding DCI. Additionally, N is defined in Equation (1), below: 
         N=N   TB   N   Rep   N   RU   N   slots   UL   (1)
 
     In Equation (1), the value of N Rep  is determined by the repetition number field in the corresponding DCI. The value of N RU  is determined by the resource assignment field in the corresponding DCI. The value of N slots   UL  is the number of NB-IoT UL slots of the resource unit corresponding to the N sc   RU  allocated number of subcarriers in the corresponding DCI. The value of N TB  is determined by the Number of scheduled TB for Unicast field, if present, in the corresponding DCI, N TB =1. Otherwise no is the first NB-IoT UL slot starting after the end of subframe n+k 0  for FDD or no is the first NB-IoT UL slot starting after k 0  NB-IoT UL subframes following the end of n+8 subframe for TDD. 
     Additionally, the value of k 0  is determined by the scheduling delay field (I Delay ) in the corresponding DCI for FDD, wherein the mapping is I Delay ={0,1,2,3} and k 0 ={8,16,32,64}, and for TDD wherein the mapping is I Delay ={0,1,2,3} and k 0 ={0,8,16,32}. 
     The value of k_offset is determined by the propagation delay field (I_offset) in the corresponding DCI according to a mapping as for example in the Table (1). The mapping can be different for the FDD and TDD case. 
     
       
         
           
               
               
               
             
               
                   
                 TABLE 1 
               
               
                   
                   
               
               
                   
                 I_offset 
                 k_offset 
               
               
                   
                   
               
             
            
               
                   
               
            
           
           
               
               
               
            
               
                   
                 0 
                 32 
               
               
                   
                 1 
                 64 
               
               
                   
                 2 
                 128 
               
               
                   
                 3 
                 256 
               
               
                   
                   
               
            
           
         
       
     
     Alternatively, a time relationships such as (i) n+k_t DL subframe for FDD or (ii) k_t NB-IoT UL subframes following the end of n+8 subframe for TDD can be used. Here, k_t is determined by a joint mapping of I_delay and I_offset. 
     For another example, the mapping between I_offset and k_offset is different from the Table (1) above, and the four values of I_offset are mapped to other values. For instance, the k_offset values are {256, 512, 1024, 2048}, or {1024, 2048, 4096, 8192}. 
     For yet another example, the mapping between I_offset and k_offset includes 8 values and I_offset field in the corresponding DCI is 3 bits. It is also possible that 16 values are used and the I_offset field in the corresponding DCI is 4 bits. When the mapping is extended and k_offset values can be more than 4, the value k 0  used in the timing relationship can be the maximum value (64 and 32 for FDD and TDD, respectively). 
     Other time relationships such as (i) n+k NTN  DL subframe for FDD or (ii) k NTN  NB-IoT UL subframes following the end of n+8 subframe for TDD, can be used. Here, the k NTN =k 0 +k_offset. The mapping between I_offset and k NTN  combines the values of k 0  and k_offset and the resulting mapping of I_offset and k NTN  is a 1-to-1 mapping. 
     In certain embodiments, a gNB (such as the BS  102 ) can configure different mappings of I_offset and k_offset, and indicate to the UE the mapping by DCI signaling or by higher layer signaling. 
     A k_offset can be provided in a DCI format. Either I_offset or k_offset can be provided in SIB, or can be configured in a preconfigured time resources configuration, or can be configured in a time offset configuration. 
     Embodiments of the present disclosure also describe determining a timing relationship of a narrowband random access response grant to NPUSCH format 1. 
     In certain embodiments, in NTN a timing offset is associated to the transmission of a NPUSCH format 1 scheduled by Narrowband RAR Grant. The higher layers indicate the Narrowband RAR Grant to the physical layer, which includes 2 bits for the scheduling delay field (I Delay ) with k 0 =12 for I Delay =0, where NB-IoT DL subframe n is the last subframe in which the NPDSCH associated with the Narrowband RAR Grant is transmitted. An additional delay offset k_offset is added and the relationships described above for NPUSCH format 1 transmission scheduled by a NPDCCH with DCI format NO are also valid when the scheduling of NPUSCH format 1 is done by a Narrowband RAR Grant. 
     Embodiments of the present disclosure also describe determining a timing relationship of a NPDSCH to HARQ-ACK on NPUSCH format 2. 
     In certain embodiments, in NTN a timing offset is associated to the transmission of a NPUSCH format 2 that indicates an HARQ-ACK information and is scheduled by an NPDSCH. The same logic for an additional delay offset k_offset used in the above timing relationships for transmission of NPUSCH format 1 applies also to the transmission of NPUSCH format 2. The timing relationships for NTN NB-IoT can be as follows. 
     For example, a UE shall upon detection of a NPDSCH transmission ending in NB-IoT subframe n intended for the UE and for which an ACK/NACK shall be provided, start, after the end of n+k 0 ′−1+k_offset of a DL subframes for FDD or k 0 ′−1+k_offset of a -IoT UL subframes following the end of n+12 subframe for TDD, transmission of the NPUSCH format 2 in N consecutive NB-IoT UL slots. 
     Embodiments of the present disclosure also describe determining a timing relationship of a preamble transmission initiated by a PDCCH order channel. 
     In certain embodiments, in NTN, a timing offset is associated to a NPRACH preamble transmission of a random access procedure initiated by a PDCCH order channel. For example, when a UE (such as the UE  116 ) receives a PDCCH order ending in subframe n, the UE shall, if requested by higher layers, start transmission of random access preamble at the end of the first subframe n+k 2 +k_offset, k 2 ≥8, where a NPRACH resource is available. The timing relationship can also be expressed as n+k 2NTN , wherein the value of k 2NTN  is a function of k_offset which depends on the round trip delay and is determined by one of the methods described above in this disclosure. 
     Embodiments of the present disclosure also describe determining a timing relationship of a NPRACH preamble retransmission. 
     Here, a timing offset is associated to a retransmission of a PRACH preamble. In NTN, after a PRACH transmission, if a random access response is received and the corresponding DL-SCH transport block ending in subframe n does not contain a response to the transmitted preamble sequence, or if no NPDCCH scheduling random access response is received in subframe n, where subframe n is the last subframe of the random access response window, or if an NPDCCH scheduling random access response with associated RA-RNTI is detected and the corresponding DL-SCH transport block reception ending in subframe n cannot be successfully decoded, the UE shall, if requested by higher layers, be ready to transmit a new preamble sequence no later than the NB-IoT UL slot starting 12 milliseconds after the end of subframe n (subframe n is a DL frame). 
     Embodiments of the present disclosure also describe determining a subframe number of initialization of the scrambling sequence generator. 
     Here, for NTN the timing offset value can be several seconds and after a UE applies the timing adjustment by an additional delay k_offset, the subframe number where a NPUSCH transmission starts is changed to ns=n+k0+k_offset. The value ns that takes into account the additional offset k_offset is used to initialize the scrambling sequence generator. For codeword q the scrambling sequence generator shall be initialized as described in Equation (2). 
         c   init   =n   RNTI ·2 14   +q· 2 13   +└n   s /2┘·2 9   +N   ID   cell   (2)
 
     At the start of each subframe where n RNTI  corresponds to the RNTI associated with the PUSCH transmission and ns is the subframe where the PUSCH transmission starts, wherein the RNTI can be C-RNTI, PUR-RNTI, TC-RNTI, SPS C-RNTI, CS-RNTI, and the like. 
     The above flowcharts illustrate example methods that can be implemented in accordance with the principles of the present disclosure and various changes could be made to the methods illustrated in the flowcharts herein. For example, while shown as a series of steps, various steps in each figure could overlap, occur in parallel, occur in a different order, or occur multiple times. In another example, steps may be omitted or replaced by other steps. 
     Although the figures illustrate different examples of user equipment, various changes may be made to the figures. For example, the user equipment can include any number of each component in any suitable arrangement. In general, the figures do not limit the scope of this disclosure to any particular configuration(s). Moreover, while figures illustrate operational environments in which various user equipment features disclosed in this patent document can be used, these features can be used in any other suitable system. 
     Although the present disclosure has been described with exemplary embodiments, various changes and modifications may be suggested to one skilled in the art. It is intended that the present disclosure encompass such changes and modifications as fall within the scope of the appended claims. None of the description in this application should be read as implying that any particular element, step, or function is an essential element that must be included in the claims scope. The scope of patented subject matter is defined by the claims.