RACH procedure for non-terrestrial networks of base stations

Abstract

The present invention discloses a method and system for enhancing the NR RACH process to accommodate non-terrestrial networks (NTNs). The length of the RAR window can be extended. In one aspect, the gNB of the NTN can perform blind retransmissions of RAR messages scheduled by DCI to user equipment within the RAR window to improve the transmission reliability of the RAR messages of the NTN. The number and transmission mode of the blind retransmissions can depend on PRACH reception conditions, uplink channel conditions, or can be preconfigured. In one aspect, due to the long propagation delay associated with the NTN, the gNB can extend the K1 and K2 values ​​that determine the delay between uplink and downlink transmissions to align with a time domain duplex (TDD) uplink-downlink configuration. In one aspect, the gNB can broadcast or multicast the RAR window size extension value to the UE based on the satellite's orbital altitude.

Description

Technical Field

[0001] The present disclosure relates to the field of wireless communications, and more particularly to methods and systems that enable a wireless communication device to perform a random access channel (RACH) procedure to a non-terrestrial network. Other aspects are also described. Background Art

[0002] As the number of mobile devices connected to wireless networks and the demand for mobile data traffic continue to increase, changes are being made to system requirements and architectures to meet the current and expected rapid growth in demand. For example, wireless communication networks such as 5G New Radio (NR) systems may need to be deployed using satellites as part of non-terrestrial networks (NTNs). In one deployment scenario of NTN, satellites known as transparent satellites can act as relay stations to link user devices with land-based base stations and 5G core networks by implementing transparent payloads. In another deployment scenario, satellites known as regenerative satellites can have onboard processing capabilities to perform the functions of a base station by implementing regenerative payloads between user devices and the land-based 5G core network. Due to the wide coverage of satellites and the long distance between satellites and ground user devices, the propagation delay difference between two user devices within the beam footprint is greater than the propagation delay difference encountered in a strict terrestrial network. For example, for an NTN deploying satellites in geostationary orbit (GEO), the maximum differential delay between the lowest point and the point at the edge of the coverage area can be 10.3ms. For satellites deploying NTN in low earth orbit (LEO), the maximum differential delay may be 3.12 ms and 3.18 ms for altitudes of 600 km and 1200 km, respectively.

[0003] When a user equipment performs a contention-based RACH procedure to gain initial access to the NTN, large propagation delays for the user equipment and large variations in propagation delays between user equipment within a beam footprint can cause problems. The user equipment can initiate the RACH procedure by sending a physical random access channel (PRACH) transmission to the base station. The user equipment can transmit the PRACH transmission as a preamble during a system frame using time-frequency resources uniquely associated with the user equipment's random access radio network temporary identifier (RA-RNTI). The base station can derive the RA-RNTI of the user equipment transmitting the PRACH from the time-frequency resources carrying the PRACH and can send a random access response (RAR) whose scheduled downlink control information (DCI) cyclic redundancy check (CRC) is scrambled by the RA-RNTI to identify the RAR as intended for the user equipment. The user equipment can search for the RAR in the common search space by attempting to decode the RAR using its RA-RNTI. When the user equipment successfully decodes the RAR, the user equipment can transmit using the uplink resources granted by the RAR to attempt to gain access to the network.

[0004] The common search space, known as the RAR window (during which a user device searches for RARs), lasts only one frame, which may be too short to accommodate the maximum differential delay of a user device performing a RACH procedure in an NTN. If the RAR window is extended, it may be more ambiguous for the user device to determine whether a RAR is intended for that RAR window, because the RAR window may contain multiple RARs generated in response to multiple user devices with the same RA-RNTI transmitting PRACH using the same time-frequency resources in different system frames that span the maximum differential delay. That is, multiple RARs within the RAR window may have their CRCs scrambled by the same RA-RNTI, making it difficult for the user device to determine whether it is the intended recipient of the RAR. Other complications may arise with RACH procedures in NTNs, including determining whether and how to delay the start of the RAR window due to a long maximum propagation delay. Summary of the Invention

[0005] The present invention discloses a method and system for enhancing the NR RACH process to adapt to non-terrestrial networks (NTNs). The RACH process from a user equipment (UE) or from a base station (referred to as a "gNodeB" or "gNB" for 5G NR) can be modified. The start of the RAR window and the length of the RAR window can be extended according to the range of propagation delay (e.g., LEO or GEO satellites). When the length of the RAR window is extended, the NTN-RNTI associated with the time-frequency resource used for the PRACH preamble can be used to scramble the CRC of the downlink control information (DCI) format 1_0 for the downlink allocation in the RAR. The DCI format 1_0 content may include information about the associated PRACH preamble to help the UE distinguish between RARs generated as a response to PRACH preambles transmitted from different system frames by different UEs based on the same RA-RNTI. In one aspect, when the UE sends the PRACH preamble, the NTN-RNTI may contain information about the system frame. In one aspect, RA-RNTIs associated with time-frequency resources used for PRACH preambles transmitted from different frames may be used to scramble different subsets of the CRC of DCI format 1_0 to help UEs distinguish RARs generated in response to different PRACH preambles.

[0006] In one aspect, the UE may perform a blind retransmission of the PRACH preamble to indicate an extension of the RAR window. In one aspect, the UE may change the RAR window offset that determines the start of the RAR window from the end of the PRACH preamble transmission based on knowledge of the location information and therefore the propagation delay of the UE.

[0007] In one aspect, the gNB may perform blind retransmissions of the RAR within the RAR window to improve transmission reliability for NTN. The number and transmission pattern of blind retransmissions may depend on PRACH reception conditions, uplink channel conditions, or may be preconfigured. In one aspect, due to the long propagation delay associated with NTN, the gNB may extend the K1 and K2 values ​​that determine the delay between uplink and downlink transmissions to align with time domain duplex (TDD) uplink-downlink configurations. In one aspect, the gNB may broadcast or multicast the RAR window size extension value to UEs based on the satellite's orbital altitude.

[0008] The above summary does not include an exhaustive list of all aspects of the present disclosure. It is contemplated that the various aspects of the present disclosure include all systems and methods that can be implemented by all suitable combinations of the various aspects summarized above and disclosed in the detailed description below and particularly pointed out in the claims filed with this patent application. Such combinations have particular advantages not specifically recited in the above summary. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Various aspects of the present disclosure are described by way of example and not by way of limitation in the drawings, in which similar reference numerals indicate similar elements. It should be noted that references to "one" or "an" aspect in the present disclosure are not necessarily to the same aspect, and are intended to refer to at least one aspect. In addition, for the sake of brevity and to reduce the total number of drawings, a given drawing may be used to illustrate features of more than one aspect of the present disclosure, and not all elements in the drawing may be required for a given aspect.

[0010] Figure 1 An exemplary wireless communication system according to some aspects of the present disclosure is shown.

[0011] Figure 2 A base station (BS) is shown in communication with a user equipment (UE) device according to some aspects of the present disclosure.

[0012] Figure 3 An exemplary block diagram of a UE according to some aspects of the present disclosure is shown.

[0013] Figure 4 An exemplary block diagram of a BS according to some aspects of the present disclosure is shown.

[0014] Figure 5 An exemplary block diagram of cellular communication circuitry according to some aspects of the present disclosure is shown.

[0015] Figure 6 DCI field based RAR window size extension according to some aspects of the present disclosure is shown.

[0016] Figure 7RNTI-based RAR window size extension according to some aspects of the present disclosure is shown.

[0017] Figure 8 Blind PRACH retransmissions by a UE over multiple frame numbers are shown to indicate an expansion of the RAR window size in accordance with aspects of the present disclosure.

[0018] Figure 9 Different locations for masking DCI using RA-RNTI are shown according to some aspects of the present disclosure.

[0019] Figure 10 The timing relationship in the NTN between a base station and a UE using a timing advance adjustment to the UE based on the round trip propagation delay between the base station and the UE is shown.

[0020] Figure 11 is a data flow diagram illustrating an example of a method for a UE to transmit a PRACH preamble to a base station and receive a RAR message from the base station over an extended RAR window to perform a RACH procedure according to some aspects of the present disclosure.

[0021] Figure 12 is a flow chart illustrating an example of a method for a base station to receive a PRACH preamble from a UE, determine an RNTI, and transmit a RAR to the UE over an extended RAR window based on the RNTI, according to some aspects of the present disclosure. DETAILED DESCRIPTION

[0022] The present invention discloses techniques for enhancing the NR RACH process to accommodate non-terrestrial networks (NTNs) or other networks with long propagation delays. The start of the RAR window for the RACH process and the length of the RAR window can be extended based on the range of propagation delays (e.g., LEO or GEO satellites). The RNTI associated with the time-frequency resources used for the PRACH preamble and the frame number of the UE's transmission of the PRACH can be used to scramble the CRC of DCI format 1_0 in the RAR to help the UE distinguish between the RAR intended for the UE and the RAR generated as a response to the PRACH preamble transmitted by other UEs during different system frames.

[0023] In one aspect, a method for a UE to access an NTN is disclosed. The method includes the UE transmitting a PRACH preamble to a base station of the NTN (such as a gNB for 5G NR) during a frame to request access to the NTN. The frame may be part of a frame structure that includes multiple frames. The method also includes the UE receiving a RAR message from the base station during a RAR window. The RAR window may span multiple frames of the frame structure. The method also includes the UE determining, based on an indication in downlink control information (DCI) that schedules the RAR message, whether the RAR message received from the base station is intended for the UE.

[0024] In one aspect, a method is disclosed for a base station, such as a 5G NR gNB, to grant access to a non-transmitted network (NTN) based on a request from a UE. The method includes the base station receiving a PRACH preamble from the UE during a frame requesting access to the NTN. The method also includes the base station determining a RNTI based on the time-frequency resources of a frame used to carry the PRACH preamble. The method also includes the base station transmitting a RAR message during a RAR window that spans multiple frames. The RAR message is scheduled by a DCI that includes an indication that allows the UE to determine that the RAR message is intended for the UE based on the RNTI and the frame number of the frame used to carry the PRACH preamble.

[0025] The following description shows many specific details. However, it should be understood that aspects of the present disclosure can be practiced here without these specific details. In other cases, well-known circuits, structures, and technologies are not shown in detail to avoid obscuring the understanding of this description.

[0026] The terms used herein are only for the purpose of describing specific aspects and are not intended to limit the aspects of the present disclosure. Spatially relative terms, such as "under...", "below...", "below...", "above...", "on...", etc., may be used herein for convenience of description to describe the relationship between an element or feature and another one or more elements or one or more features, as shown in the accompanying drawings. It should be understood that spatially relative terms are intended to cover different orientations during use or operation of the device other than the orientation shown in the accompanying drawings. For example, if the device in the figure is turned over, the elements described as "below" or "below" other elements or features can then be oriented to be "above" other elements or features. Therefore, the exemplary term "below..." can cover both orientations of "above..." and "below...". The device can be oriented in other ways (e.g., rotated 90 degrees or at other orientations), and the spatially relative descriptors used in this article are interpreted accordingly.

[0027] As used herein, the singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context indicates otherwise. It should be further understood that the terms "include" and "comprise" specify the presence of stated features, steps, operations, elements, or components, but do not preclude the presence or addition of one or more other features, steps, operations, elements, components, or groups thereof.

[0028] As used herein, the terms "or" and "and / or" should be interpreted as inclusive or meaning any one or any combination. Thus, "A, B, or C" or "A, B, and / or C" means "any of the following: A; B; C; A and B; A and C; B and C; A, B, and C." An exception to this definition occurs only when a combination of elements, functions, steps, or actions are inherently mutually exclusive in some way.

[0029] Figure 1 A simplified exemplary wireless communication system according to some aspects is shown. Note that Figure 1 The system is only one example of a possible system, and features of the present disclosure may be implemented in any of a variety of systems as desired.

[0030] As shown, the exemplary wireless communication system includes a base station 102A that communicates with one or more user devices 106A, 106B, ..., 106N via a transmission medium. Each of the user devices may be referred to herein as a "user equipment" (UE). Accordingly, user device 106 is referred to as a UE or UE device.

[0031] The base station (BS) 102A may be a base transceiver station (BTS) or a cell site ("cell base station") and may include hardware that enables wireless communications with the UEs 106A through 106N. In one aspect, the base station 102A may be deployed as a satellite, referred to as a regenerative satellite, that carries onboard processing capabilities to perform the functions of a base station to implement regenerative payloads between the UEs and a ground-based core network.

[0032] The communication area (or coverage area) of a base station may be referred to as a "cell." The base station 102A and the UE 106 may be configured to communicate over a transmission medium using any of a variety of radio access technologies (RATs), also known as wireless communication technologies or telecommunication standards, such as GSM, UMTS (associated with, for example, WCDMA or TD-SCDMA air interfaces), LTE, LTE-Advanced (LTE-A), 5G New Radio (5G NR), HSPA, 3GPP2 CDMA2000 (e.g., 1xRTT, 1xEV-DO, HRPD, eHRPD), etc. Note that if the base station 102A is implemented in the context of LTE, it may alternatively be referred to as an "eNodeB" or "eNB." Note that if the base station 102A is implemented in the context of 5G NR, it may alternatively be referred to as a "gNodeB" or "gNB."

[0033] As shown, base station 102A may also be configured to communicate with network 100 (e.g., a core network of a cellular service provider, a telecommunications network such as a public switched telephone network (PSTN), and / or the Internet, among other possibilities). Thus, base station 102A may facilitate communications between user devices and / or between user devices and network 100. In particular, cellular base station 102A may provide UE 106 with various telecommunications capabilities, such as voice, short message service (SMS), and / or data services.

[0034] Base station 102A and other similar base stations (such as base stations 102B...102N) operating according to the same or different cellular communication standards can therefore provide a network of cells that can provide continuous or nearly continuous overlapping service to UEs 106A-N and similar devices over a geographic area via one or more cellular communication standards.

[0035] Thus, although base station 102A may function as Figure 1 106A-N, each UE 106 may also be capable of receiving signals from (and possibly within communication range of) one or more other cells (which may be provided by base stations 102B-N and / or any other base stations), which may be referred to as "neighboring cells." Such cells may also be capable of facilitating communications between user devices and / or between user devices and network 100. Such cells may include "macro" cells, "micro" cells, "pico" cells, and / or cells of any other variety of granularities of service area size. For example, in Figure 1The base stations 102A-B shown in FIG. 1 may be macro cells, while the base station 102N may be a micro cell. Other configurations are also possible. The UE 106 may measure the time of arrival (TOA) of positioning reference signals (PRS) transmitted by its serving base station 102A and by base stations 102B-N of neighboring cells to support position determination of the UE 106.

[0036] In some aspects, base station 102A may be a next-generation base station, such as a 5G New Radio (5G NR) base station or "gNB." In some aspects, a gNB may be connected to a legacy evolved packet core (EPC) network and / or to an NR core (NRC) network. Furthermore, a gNB cell may include one or more transition and reception points (TRPs). Furthermore, a UE capable of operating in accordance with 5G NR may connect to one or more TRPs within one or more gNBs.

[0037] It is noted that the UE 106 is capable of communicating using multiple wireless communication standards. For example, in addition to at least one cellular communication protocol (e.g., GSM, UMTS (associated with, for example, WCDMA or TD-SCDMA air interfaces), LTE, LTE-A, 5G-NR, HSPA, 3GPP2 CDMA2000 (e.g., 1xRTT, 1xEV-DO, HRPD, eHRPD), etc.), the UE 106 can be configured to communicate using wireless networking (e.g., Wi-Fi) and / or peer-to-peer wireless communication protocols (e.g., Bluetooth, Wi-Fi peer-to-peer, etc.). If desired, the UE 106 can also or alternatively be configured to communicate using one or more global navigation satellite systems (GNSS, such as GPS or GLONASS), one or more mobile television broadcast standards (e.g., ATSC-M / H or DVB-H), and / or any other wireless communication protocols. Other combinations of wireless communication standards (including more than two wireless communication standards) are also possible.

[0038] Figure 2 A user equipment 106 (e.g., one of devices 106A-106N) is shown in accordance with some aspects in communication with base station 102. UE 106 may be a device with cellular communication capabilities such as a mobile phone, handheld device, computer or tablet, or virtually any type of wireless device.

[0039] The UE 106 may include a processor configured to execute program instructions stored in a memory. The UE 106 may perform any of the methods described herein by executing such stored instructions. Alternatively or in addition, the UE 106 may include a programmable hardware element, such as an FPGA (field programmable gate array), configured to perform any of the methods described herein or any portion of any of the methods described herein.

[0040] The UE 106 may include one or more antennas for communicating using one or more wireless communication protocols or technologies. In some aspects, the UE 106 may be configured to communicate using, for example, CDMA2000 (1xRTT / 1xEV-DO / HRPD / eHRPD) or LTE or 5G NR using a single shared radio and / or GSM or LTE or 5G NR using a single shared radio. The shared radio may be coupled to a single antenna or to multiple antennas (e.g., for MIMO) for performing wireless communications. Generally, the radio may include any combination of a baseband processor, analog radio frequency (RF) signal processing circuitry (e.g., including filters, mixers, oscillators, amplifiers, etc.), or digital processing circuitry (e.g., for digital modulation and other digital processing). Similarly, the radio may implement one or more receive and transmit chains using the aforementioned hardware. For example, the UE 106 may share one or more portions of a receive and / or transmit chain between multiple wireless communication technologies, such as those described above.

[0041] In some aspects, the UE 106 may include a separate transmit chain and / or receive chain (e.g., including separate antennas and other radio components) for each wireless communication protocol with which it is configured to communicate. As another possibility, the UE 106 may include one or more radio components shared between multiple wireless communication protocols, and one or more radio components used exclusively by a single wireless communication protocol. For example, the UE 106 may include a shared radio component for communicating using any of LTE or 5G-NR (or LTE or 1xRTT, or LTE or GSM), and separate radio components for communicating using each of Wi-Fi and Bluetooth. Other configurations are also possible.

[0042] Figure 3 1 shows an exemplary simplified block diagram of a communication device 106 according to some aspects. Figure 3The block diagram of the communication device is only one example of a possible communication device. According to various aspects, the communication device 106 can be, among other devices, a user equipment (UE) device, a mobile device or mobile station, a wireless device or wireless station, a desktop computer or computing device, a mobile computing device (e.g., a laptop, notebook, or portable computing device), a tablet computer, and / or a combination of devices. As shown, the communication device 106 may include a set of components 300 configured to perform core functions. For example, the set of components may be implemented as a system on a chip (SOC), which may include parts for various purposes. Alternatively, the set of components 300 may be implemented as individual components or groups of components for various purposes. This set of components 300 may be coupled (e.g., communicatively; directly or indirectly) to various other circuits of the communication device 106.

[0043] For example, the communication device 106 may include various types of memory (e.g., including NAND flash memory 310), input / output interfaces such as a connector I / F 320 (e.g., for connecting to a computer system; a docking station; a charging station; input devices such as a microphone, a camera, a keyboard; output devices such as a speaker; etc.), a display 360 that may be integrated with the communication device 106 or external to the communication device, and cellular communication circuitry 330 such as for 5G-NR, LTE, GSM, etc., and short-range to medium-range wireless communication circuitry 329 (e.g., Bluetooth TM and WLAN circuitry). In some aspects, the communication device 106 may include wired communication circuitry (not shown), such as, for example, a network interface card for Ethernet.

[0044] Cellular communication circuitry 330 may be (e.g., communicatively; directly or indirectly) coupled to one or more antennas, such as antennas 335 and 336, as shown. Short-range to medium-range wireless communication circuitry 329 may also be (e.g., communicatively; directly or indirectly) coupled to one or more antennas, such as antennas 337 and 338, as shown. Alternatively, short-range to medium-range wireless communication circuitry 329 may be (e.g., communicatively; directly or indirectly) coupled to antennas 335 and 336, in addition to or in lieu of being (e.g., communicatively; directly or indirectly) coupled to antennas 337 and 338. Short-range to medium-range wireless communication circuitry 329 and / or cellular communication circuitry 330 may include multiple receive chains and / or multiple transmit chains for receiving and / or transmitting multiple spatial streams, such as in a multiple-input, multiple-output (MIMO) configuration.

[0045] In some aspects, as further described below, the cellular communication circuitry 330 can include dedicated receive chains (including and / or (e.g., communicatively, directly or indirectly) coupled to a dedicated processor and / or radio) for multiple RATs (e.g., a first receive chain for LTE and a second receive chain for 5G NR). Furthermore, in some aspects, the cellular communication circuitry 330 can include a single transmit chain that can switch between radios dedicated to specific RATs. For example, a first radio can be dedicated to a first RAT, such as LTE, and can communicate with a dedicated receive chain as well as a transmit chain shared with an additional radio, such as a second radio that can be dedicated to a second RAT (e.g., 5G NR) and can communicate with both the dedicated receive chain and the shared transmit chain.

[0046] The communication device 106 may also include and / or be configured for use with one or more user interface elements. User interface elements may include various elements such as a display 360 (which may be a touch screen display), a keyboard (which may be a separate keyboard or may be implemented as part of the touch screen display), a mouse, a microphone and / or speakers, one or more cameras, one or more buttons, and / or any of a variety of other elements capable of providing information to a user and / or receiving or interpreting user input.

[0047] The communication device 106 may also include one or more smart cards 345 having SIM (Subscriber Identity Module) functionality, such as one or more UICC cards (one or more Universal Integrated Circuit Cards) 345 .

[0048] As shown, the SOC 300 may include a processor 302 that may execute program instructions for the communication device 106 and a display circuit 304 that may perform graphics processing and provide display signals to a display 360. The processor 302 may also be coupled to a memory management unit (MMU) 340 (the MMU may be configured to receive addresses from the processor 302 and translate those addresses into locations in memory (e.g., memory 306, read-only memory (ROM) 350, NAND flash memory 310)) and / or to other circuits or devices (such as the display circuit 304, the short-range wireless communication circuit 229, the cellular communication circuit 330, the connector I / F 320, and / or the display 360). The MMU 340 may be configured to perform memory protection and page table translation or setup. In some aspects, the MMU 340 may be included as part of the processor 302.

[0049] As described above, the communication device 106 can be configured to communicate using wireless and / or wired communication circuitry. The communication device 106 can be configured to transmit a request to attach to a first network node operating according to a first RAT and to transmit an indication that the wireless device is capable of maintaining substantially concurrent connections with the first network node and a second network node operating according to a second RAT. The wireless device can also be configured to transmit a request to attach to the second network node. The request can include an indication that the wireless device is capable of maintaining substantially concurrent connections with the first and second network nodes. Furthermore, the wireless device can be configured to receive an indication that dual connectivity has been established with the first network node and the second network node.

[0050] As described herein, the communication device 106 may include hardware and software components for implementing the above-described features for time-division multiplexing UL data for NSA (non-standalone) NR operation. For example, by executing program instructions stored on a memory medium (e.g., a non-transitory computer-readable memory medium), the processor 302 of the communication device 106 may be configured to implement some or all of the features described herein. Alternatively (or in addition), the processor 302 may be configured as a programmable hardware element, such as an FPGA (field programmable gate array) or an ASIC (application-specific integrated circuit). Alternatively (or in addition), in combination with one or more of the other components 300, 304, 306, 310, 320, 329, 330, 340, 345, 350, 360, the processor 302 of the communication device 106 may be configured to implement some or all of the features described herein.

[0051] Furthermore, as described herein, processor 302 may include one or more processing elements. Thus, processor 302 may include one or more integrated circuits (ICs) configured to perform the functions of processor 302. Furthermore, each integrated circuit may include circuitry (e.g., a first circuit, a second circuit, etc.) configured to perform one or more functions of processor 302.

[0052] Furthermore, as described herein, both cellular communication circuitry 330 and short-range wireless communication circuitry 329 may include one or more processing elements. In other words, one or more processing elements may be included in cellular communication circuitry 330, and similarly, one or more processing elements may be included in short-range wireless communication circuitry 329. Thus, cellular communication circuitry 330 may include one or more integrated circuits (ICs) configured to perform the functions of cellular communication circuitry 330. Furthermore, each integrated circuit may include circuitry (e.g., a first circuit, a second circuit, etc.) configured to perform the functions of cellular communication circuitry 230. Similarly, short-range wireless communication circuitry 329 may include one or more ICs configured to perform the functions of short-range wireless communication circuitry 329. Furthermore, each integrated circuit may include circuitry (e.g., a first circuit, a second circuit, etc.) configured to perform the functions of short-range wireless communication circuitry 329.

[0053] Figure 4 1 shows an exemplary block diagram of a base station 102 according to some aspects. Figure 4 The base station 102 is only one example of a possible base station. As shown, the base station 102 may include a processor 404 that may execute program instructions for the base station 102. The processor 404 may also be coupled to a memory management unit (MMU) 440 or other circuit or device that may be configured to receive addresses from the processor 404 and translate those addresses into locations in memory (e.g., memory 460 and read-only memory (ROM) 450).

[0054] The base station 102 may include at least one network port 470. The network port 470 may be configured to couple to a telephone network and provide access to the telephone network as described above. Figure 1 and Figure 2 Multiple devices of the telephone network described in, such as UE device 106.

[0055] The network port 470 (or an additional network port) may also or alternatively be configured to couple to a cellular network, such as a core network of a cellular service provider. The core network may provide mobility-related services and / or other services to a plurality of devices, such as the UE device 106. In some cases, the network port 470 may be coupled to a telephone network via the core network, and / or the core network may provide a telephone network (e.g., in other UE devices served by the cellular service provider).

[0056] In some aspects, base station 102 may be a next-generation base station, such as a 5G New Radio (5GNR) base station or "gNB." In such aspects, base station 102 may be connected to a legacy evolved packet core (EPC) network and / or to an NR core (NRC) network. Furthermore, base station 102 may be considered a 5G NR cell and may include one or more transition and reception points (TRPs). Furthermore, a UE capable of operating in accordance with 5G NR may connect to one or more TRPs within one or more gNBs.

[0057] The base station 102 may include at least one antenna 434 and possibly multiple antennas. The at least one antenna 434 may be configured to function as a wireless transceiver and may be further configured to communicate with the UE device 106 via the radio 430. The antenna 434 communicates with the radio 430 via a communication chain 432. The communication chain 432 may be a receive chain, a transmit chain, or both. The radio 430 may be configured to communicate via various wireless communication standards, including but not limited to 5G-NR, LTE, LTE-A, GSM, UMTS, CDMA2000, Wi-Fi, and the like.

[0058] Base station 102 may be configured to communicate wirelessly using multiple wireless communication standards. In some cases, base station 102 may include multiple radio components that enable base station 102 to communicate according to multiple wireless communication technologies. For example, as one possibility, base station 102 may include an LTE radio component for performing communication according to LTE and a 5G-NR radio component for performing communication according to 5G-NR. In such a case, base station 102 may be capable of operating as both an LTE base station and a 5G-NR base station. As another possibility, base station 102 may include a multimode radio component capable of performing communication according to any of multiple wireless communication technologies (e.g., 5G-NR and Wi-Fi, LTE and Wi-Fi, LTE and UMTS, LTE and CDMA2000, UMTS and GSM, etc.). As further described later herein, BS 102 may include hardware and software components for implementing or supporting the implementation of the features described herein. The processor 404 of base station 102 may be configured to implement or support some or all of the implementations of the methods described herein, for example, by executing program instructions stored on a memory medium (e.g., a non-transitory computer-readable memory medium). Alternatively, the processor 404 may be configured as a programmable hardware element such as an FPGA (field programmable gate array), or as an ASIC (application-specific integrated circuit), or a combination thereof. Alternatively (or in addition), in conjunction with one or more of the other components 430, 432, 434, 440, 450, 460, 470, the processor 404 of the BS 102 may be configured to implement or support some or all of the features described herein.

[0059] Furthermore, as described herein, processor 404 may be comprised of one or more processing elements. In other words, one or more processing elements may be included in processor 404. Thus, processor 404 may include one or more integrated circuits (ICs) configured to perform the functions of processor 404. Furthermore, each integrated circuit may include circuitry (e.g., a first circuit, a second circuit, etc.) configured to perform the functions of processor 404.

[0060] Additionally, as described herein, radio 430 may be comprised of one or more processing elements. In other words, one or more processing elements may be included in radio 430. Thus, radio 430 may include one or more integrated circuits (ICs) configured to perform the functions of radio 430. Furthermore, each integrated circuit may include circuitry (e.g., a first circuit, a second circuit, etc.) configured to perform the functions of radio 430.

[0061] Figure 5 An exemplary simplified block diagram of a cellular communication circuit according to some aspects is shown. Note that Figure 5 The block diagram of the cellular communication circuitry is merely one example of possible cellular communication circuitry. According to various aspects, the cellular communication circuitry 330 may be included in a communication device such as the communication device 106 described above. As described above, the communication device 106 may be a user equipment (UE) device, a mobile device or station, a wireless device or station, a desktop computer or computing device, a mobile computing device (e.g., a laptop, notebook, or portable computing device), a tablet computer, and / or a combination of devices, among other devices.

[0062] Cellular communication circuitry 330 may be (eg, communicatively; directly or indirectly) coupled to one or more antennas, such as ( Figure 3 In some aspects, the cellular communication circuitry 330 may include dedicated receive chains (including and / or (e.g., communicatively; directly or indirectly) coupled to dedicated processors and / or radio components) for multiple RATs (e.g., a first receive chain for LTE and a second receive chain for 5G NR). For example, Figure 5 As shown, cellular communication circuitry 330 may include a modem 510 and a modem 520. Modem 510 may be configured for communication according to a first RAT, such as, for example, LTE or LTE-A, and modem 520 may be configured for communication according to a second RAT, such as, for example, 5G NR.

[0063] As shown, the modem 510 may include one or more processors 512 and a memory 516 in communication with the processor 512. The modem 510 may be in communication with a radio frequency (RF) front end 530. The RF front end 530 may include circuitry for transmitting and receiving radio signals. For example, the RF front end 530 may include receive circuitry (RX) 532 and transmit circuitry (TX) 534. In some aspects, the receive circuitry 532 may be in communication with a downlink (DL) front end 550, which may include circuitry for receiving radio signals via antenna 335a.

[0064] Similarly, the modem 520 may include one or more processors 522 and a memory 526 in communication with the processor 522. The modem 520 may be in communication with an RF front end 540. The RF front end 540 may include circuitry for transmitting and receiving radio signals. For example, the RF front end 540 may include receive circuitry 542 and transmit circuitry 544. In some aspects, the receive circuitry 542 may be in communication with a DL front end 560, which may include circuitry for receiving radio signals via the antenna 335b.

[0065] In some aspects, the switch 570 may couple the transmit circuitry 534 to an uplink (UL) front end 572. Furthermore, the switch 570 may couple the transmit circuitry 544 to the UL front end 572. The UL front end 572 may include circuitry for transmitting radio signals via the antenna 336. Thus, when the cellular communication circuitry 330 receives an instruction to transmit according to a first RAT (e.g., via a transmit chain including the transmit circuitry 534 and the UL front end 572), the switch 570 may be switched to a first state that allows the modem 510 to transmit signals according to the first RAT (e.g., via a transmit chain including the transmit circuitry 534 and the UL front end 572). Similarly, when the cellular communication circuitry 330 receives an instruction to transmit according to a second RAT (e.g., via a transmit chain including the transmit circuitry 544 and the UL front end 572), the switch 570 may be switched to a second state that allows the modem 520 to transmit signals according to the second RAT (e.g., via a transmit chain including the transmit circuitry 544 and the UL front end 572).

[0066] As described herein, the modem 510 may include hardware and software components for implementing the above-described features or for time-division multiplexing UL data for NSA NR operations and various other techniques described herein. For example, by executing program instructions stored on a memory medium (e.g., a non-transitory computer-readable memory medium), the processor 512 may be configured to implement some or all of the features described herein. Alternatively (or in addition), the processor 512 may be configured as a programmable hardware element such as an FPGA (field programmable gate array) or as an ASIC (application-specific integrated circuit). Alternatively (or in addition), in combination with one or more of the other components 530, 532, 534, 550, 570, 572, 335, and 336, the processor 512 may be configured to implement some or all of the features described herein.

[0067] Furthermore, as described herein, processor 512 may include one or more processing elements. Thus, processor 512 may include one or more integrated circuits (ICs) configured to perform the functions of processor 512. Furthermore, each integrated circuit may include circuitry (e.g., a first circuit, a second circuit, etc.) configured to perform the functions of processor 512.

[0068] As described herein, the modem 520 may include hardware and software components for implementing the above-described features or for time-division multiplexing UL data for NSA NR operations and various other technologies described herein. For example, by executing program instructions stored on a memory medium (e.g., a non-transitory computer-readable memory medium), the processor 522 may be configured to implement some or all of the features described herein. Alternatively (or in addition), the processor 522 may be configured as a programmable hardware element such as an FPGA (field programmable gate array) or as an ASIC (application-specific integrated circuit). Alternatively (or in addition), in combination with one or more of the other components 540, 542, 544, 550, 570, 572, 335, and 336, the processor 522 may be configured to implement some or all of the features described herein.

[0069] Furthermore, as described herein, processor 522 may include one or more processing elements. Thus, processor 522 may include one or more integrated circuits (ICs) configured to perform the functions of processor 522. Furthermore, each integrated circuit may include circuitry (e.g., a first circuit, a second circuit, etc.) configured to perform the functions of processor 522.

[0070] In 5G NR, the UE may initiate a RACH procedure to obtain initial access to the network. In the 4-step contention-based RACH procedure, the UE may send a PRACH to the base station in the first step. The PRACH (also referred to as Msg1) or PRACH preamble may contain 1 preamble out of 64 preambles (long or short preambles) sent in a RACH opportunity (RO). The UE may power ramp up the PRACH after each failed PRACH transmission. The UE may transmit the PRACH in a frame using time-frequency resources uniquely associated with the UE's RA-RNTI. For example, the RA-RNTI may be determined based on the index of the first orthogonal frequency division multiplexing (OFDM) symbol of the PRACH, the index of the first time slot of the PRACH in the transmitted frame, the index of the PRACH in the frequency domain, etc. There is a possibility that more than one UE transmits the same PRACH on the same time-frequency resources in a frame.

[0071] The UE can use timing advance (TA) adjustment to transmit PRACH to account for propagation delay from the UE to the base station, so that the PRACH is time-aligned with the system frame structure when received by the base station. The UE can automatically obtain a UE-specific TA based on its known location and satellite ephemeris. Alternatively, the base station can broadcast a common TA based on a satellite beam or a reference point in the cell. The base station can also transmit a UE-specific differential TA to the UE based on network instructions, so that the UE can derive the complete TA as the sum of the common TA and the differential TA.

[0072] In the second step of the RACH process, in response to the PRACH from the UE, the base station may send a RAR (also referred to as Msg2) or RAR message. The base station may derive the RA-RNTI of the user equipment transmitting the PRACH from the time-frequency resources carrying the PRACH. The RAR may be scheduled by DCI format 1_0 carried on the physical downlink control channel (PDCCH) with a CRC scrambled by the RA-RNTI. The UE may attempt to decode the DCI format 1_0 using its RA-RNTI in the common search space of the RAR window. The RAR may also be included in a medium access control physical data unit (MAC PDU) carried on the physical downlink shared channel (PDSCH) specified by the DCI format 1_0. The subheader of the MAC PDU may include a 6-bit random access preamble ID (RAPID) or a 4-bit fallback indicator (BI). The MAC PDU may include a 12-bit timing advance (TA) command, a 27-bit uplink grant, and a 16-bit temporary cell-RNTI (TC-RNTI). The TC-RNTI may be used by the UE for the rest of the RACH procedure.

[0073] The UE may search for RAR during the common search space of the RAR window. The RAR window may start after Msg1 and may last up to 1 frame or 10ms. Because more than one UE may have transmitted the same PRACH on the same time-frequency resources in a frame, multiple UEs may attempt to decode DCI format 1_0 of a PDCCH with a CRC scrambled by the same RA-RNTI. Therefore, multiple UEs may decode DCI format 1_0, obtain the MAC PDU for RAR from the PDSCH specified by DCI format 1_0, and compete for access to the network.

[0074] In the third step of the RACH procedure, after the UE receives the RAR, it may send a control element, which may be called Msg3, on the physical uplink shared channel (PUSCH) allocated by the RAR. The UE may scramble Msg3 using the TC-RNTI received in the RAR. Msg3 may contain the cell-RNTI (C-RNTI), a unique identifier of the UE used by the base station to allocate uplink grants to the UE, downlink assignments, etc. If the base station fails to decode Msg3, the base station may reschedule the retransmission of Msg3 using DCI format 0_0 of the PDCCH with a CRC scrambled by the TC-RNTI.

[0075] In the fourth step of the RACH process, after the base station decodes Msg3, the base station may send a contention resolution identification MAC control element in Msg4. Msg4 may be carried on the PDSCH specified by the DCI format 1_0 of the PDCCH with a CRC scrambled by the TC-RNTI. For UEs that win the contention and do not yet have a C-RNTI, the TC-RNTI may be promoted to a C-RNTI. If the UE successfully completes the RACH process and already has a C-RNTI, it may recover using its C-RNTI and may discard the TC-RNTI received in the RAR. The UE may transmit a hybrid automatic repeat request acknowledgement (HARQ-ACK) signal on the PUCCH after decoding Msg4.

[0076] To speed up the RACH process, 5G NR introduces a 2-step RACH process. In the first step of the 2-step RACH process, the UE can send a MsgA containing PRACH and PUSCH. The RACH opportunity (RO) for PRACH and the PUSCH opportunity (PO) for PUSCH can have a fixed resource mapping. The PO mapping does not overlap with the RO. The RO configured for 2-step RACH can be separate from or shared with the RO configured for 4-step RACH. The PUSCH can contain a scrambling sequence initialization value that depends on the RA-RNTI and RAPID, as well as a radio resource control (RRC) connection request with or without additional uplink data.

[0077] In the second step of the 2-step RACH procedure, in response to receiving MsgA, the base station may transmit a RAR, called MsgB. MsgB may contain the PDCCH and PDSCH. The PDSCH contains a successful RAR MAC when the PUSCH is successfully received by the base station, and a fallback RAR MAC otherwise. The successful RAR MAC may contain contention resolution ID, TA, C-RNTI, etc. The fallback RAR MAC may contain a fallback indicator for the PRACH and PUSCH for the UE to retransmit MsgA. The UE may search for MsgB in the RAR window. The RAR window may start after the MsgA PUSCH transmission and may last up to 4 frames or 40ms.

[0078] If the UE is in connected mode, the PDCCH for MsgB may include DCI format 1_0 with a CRC scrambled by the C-RNTI. Otherwise, the CRC of DCI format 1_0 is scrambled by the MsgB-RNTI. The UE may attempt to decode a DCI format 1_0 specifying a PDSCH containing a successful RAR MAC or fallback RAR MAC using either the MsgB-RNTI or the C-RNTI in the RAR window.

[0079] Figure 6FIG1 illustrates an example of a DCI field-based RAR window size extension according to one aspect of the present disclosure. Depending on whether the satellite in the NTN is a LEO satellite or a GEO satellite, the RAR window size can be extended for the 4-step RACH process. For LEO satellites, the maximum differential delay can be 3.12 ms and 3.18 ms for satellite altitudes of 600 km and 1200 km, respectively. Because 2 times the maximum differential delay is less than the nominal 10 ms of the RAR window, an extension of the RAR window may not be necessary. However, for GEO satellites, the maximum differential delay between the lowest point and a point at the edge of the coverage area can be 10.3 ms. An extension of the RAR window size may be required because 2 times the maximum differential delay is close to 20 ms, or 2 frames.

[0080] In one aspect, if the RAR window size is extended to 20ms for GEO satellites, the DCI field may indicate the RAR window size extension. In Msg2 transmissions, the CRC of DCI format 1_0 may be scrambled by the new NTN-RNTI in the common search space. Similar to the RA-RNTI, the NTN-RNTI may be determined based on the time-frequency resources used to transmit the PRACH in the RACH opportunity. In one aspect, the NTN-RNTI may be determined based on the starting symbol index s_id of the PRACH, the starting slot index t_id of the PRACH in the transmitted frame, the frequency domain index f_id, and the uplink carrier ul_carrier_id used to carry the PRACH, but with an additional offset such that the NTN-RNTI is different from the MsgB-RNTI for the 2-step RACH procedure. For example, the NTN_RNTI may be equal to (1+s_id+14×t_id+14×80×f_id+14×80×8×ul_carrier_id+14×80×8×4). The range of NTN-RNTI can be 35841 to 53760 to avoid conflict with the range of RA-RNTI values ​​1 to 17920 and the range of MsgB-RNTI values ​​17921 to 35840. When a PRACH triggering DCI format 1_0 is transmitted, DCI format 1_0 also has a field indicating the least significant bit of the system frame number (SFN).

[0081] When transmitting the PRACH, the UE already knows the NTN-RNTI and SFN. Therefore, the UE can use its NTN-RNTI to decode DCI format 1_0. When the UE transmits the PRACH, the UE can also verify that the bit field in DCI format 1_0 indicating the last bit of the SFN associated with the PRACH that triggered DCI format 1_0 matches the last bit of the SFN. Therefore, the UE can determine whether the RAR received during the extended RAR window is intended for the UE to distinguish it from the RAR intended for another UE transmitting the PRACH using the same time-frequency resources but on a different frame. For example, if a UE transmits a PRACH during a frame with SFN x (e.g., an even frame number), and another UE transmits the same PRACH using the same time-frequency resources during the next frame with SFN x+1 (e.g., an odd frame number), the CRC of DCI format 1_0 for the RARs of both UEs can be scrambled with the same NTN-RNTI in the common search space. However, two DCI formats 1_0 may contain a field indicating that the PRACH that triggers two RARs is transmitted on two consecutive frames. A UE transmitting PRACH on SFN x can then verify that the field in DCI format 1_0 indicates an even frame to determine that DCI format 1_0 is intended for the UE so that the UE can receive the correct RAR.

[0082] Figure 7 FIG2 shows an example of an RNTI-based RAR window size extension according to another aspect of the present disclosure. Similarly, for GEO satellites, the RAR window size is extended to 20ms. In Msg2 transmission, the CRC of DCI format 1_0 can be scrambled by the new NTN-RNTI in the common search space. However, unlike Figure 6 Unlike the DCI field-based RAR window size extension, when the PRACH that triggers the DCI field is transmitted, the NTN-RNTI here can encode the least significant bits of the SFN. For example, NTN_RNTI can be equal to (1+s_id+14×t_id+14×80×f_id+14×80×8×ul_carrier_id+14×80×8×4×(SFN mode 2)). As a result, if the RACH opportunity is in an even SFN, the NTN-RNTI is reduced to the RA-RNTI. On the other hand, if the RACH opportunity is in an odd SFN, the NTN-RNTI uses a new value that is different from the RA-RNTI. This avoids conflicts with the MsgB-RNTI value, but reuses the RA-RNTI value. That is, for even-numbered SFNs, the NTN-RNTI range may be set to [1, 17920] (set 1), and for odd-numbered SFNs, the NTN-RNTI range may be set to [35841, 53760] (set 2).

[0083] In one aspect, to reuse the value range of MsgB-RNTI, NTN_RNTI may be equal to (1+s_id+14×t_id+14×80×f_id+14×80×8×ul_carrier_id+14×80×8×2×(SFN mode 2)). The range of NTN-RNTI may be [1,35840] or [1,17920] for set 1 and may be [17921,35840] for set 2. In addition, Figure 6 Unlike the DCI field-based RAR window size extension, when a PRACH that triggers DCI format 1_0 is transmitted, DCI format 1_0 no longer indicates the least significant bit of the system frame number (SFN). The UE can calculate the NTN_RNTI based on the time-frequency resources of its RACH opportunity and the SFN when it transmits the PRACH, and can use the NTN-RNTI to determine whether the RAR received during the extended RAR window is intended for the UE. For example, if a UE transmits a PRACH during a frame with SFN x, and another UE transmits the same PRACH using the same time-frequency resources during the next frame with SFN x+1, the CRCs of the DCI format 1_0 for the RARs of the two UEs can be scrambled by different NTN-RNTIs in the common search space. The UE transmitting the PRACH on SFN x can then use its corresponding NTN-RNTI to decode DCI format 1_0 to determine that DCI format 1_0 is intended for the UE, so that the UE can receive the correct RAR.

[0084] Figure 8PRACH blind retransmissions by a UE over multiple frame numbers are shown according to another aspect of the present disclosure to indicate an extension of the RAR window size. Similarly, for GEO satellites, the RAR window size is extended to 20ms. In a Msg1 transmission, the UE transmits multiple (e.g., 2) PRACH transmissions in the same RACH opportunity (using the same time-frequency resources) repeated over multiple frames. In one aspect, the transmit power of the PRACH retransmissions may be gradually increased or remain unchanged. The preamble power ramp counter may be increased by 1 or the number of PRACH blind retransmissions may be increased. The same RA-RNTI is obtained from each of the PRACH retransmissions. That is, the RA-RNTI may be equal to (1+s_id+14×t_id+14×80×f_id+14×80×8×ul_carrier_id). In one aspect, the RACH opportunities are paired between multiple (e.g., 2) consecutive frames. For example, each UE can transmit PRACH on two consecutive frames, the first PRACH in an even SFN (SFN x) and the second PRACH in an odd SFN (SFN x+1). This avoids staggered PRACH transmissions from two different UEs in a single frame. Each UE can wait to receive a RAR message within its own 20ms RAR window by decoding DCI format 1_0 using its unique RA-RNTI.

[0085] Figure 9 The figure shows different locations of the DCI CRC masked using the RA-RNTI according to another aspect of the present disclosure. Similarly, for GEO satellites, the RAR window size is extended to 20ms. In Msg2 transmission, when the PRACH that triggers DCI format 1_0 is transmitted, different subsets of the CRC of DCI format 1_0 can be scrambled by the RA-RNTI in the common search space according to the frame number. The RA-RNTI can be equal to (1+s_id+14×t_id+14×80×f_id+14×80×8×ul_carrier_id). If the last 16 bits of the CRC of DCI format 1_0 are scrambled by the RA-RNTI, also known as masking the last 16 bits of the CRC of DCI format 1_0 with the RA-RNTI, then DCI format 1_0 corresponds to a PRACH transmitted using a RACH opportunity in an even SFN. If the penultimate 16 bits of the CRC of DCI format 1_0 are scrambled by the RA-RNTI, also referred to as masking the penultimate 16 bits of the CRC of DCI format 1_0 with the RA-RNTI, the RAR corresponds to a PRACH transmitted using a RACH opportunity in an odd SFN.

[0086] The UE can calculate the RA-RNTI based on the time-frequency resources of its RACH occasions and can determine the SFN when it transmits the PRACH. The UE can use the least significant bits of the SFN to determine which 16 bits of the CRC of DCI format 1_0 received during the extended RAR window to decode using the RN-RNTI to determine whether the RAR is intended for the UE. For example, if a UE transmits a PRACH during a frame with SFN x, and another UE transmits the same PRACH using the same time-frequency resources during the next frame with SFN x+1, different subsets of the CRC of DCI format 1_0 for the RARs of the two UEs can be scrambled by the same RA-RNTI in the common search space. The UE transmitting the PRACH on SFN x can then decode the last 16 CRC bits of DCI format 1_0 to determine that DCI format 1_0 is intended for the UE so that the UE can receive the correct RAR.

[0087] In one aspect, the RAR window offset of the RACH process can be modified. The RAR window offset can be modified for both the 4-step RACH process and the 2-step RACH process. In one aspect, in a unified design, a common timing advance (TA) based on a reference point in a satellite beam or cell can be used as the RAR window offset for all UEs. In one aspect, the common TA is used as the RAR window offset for all UEs without location information. The UE can send Msg1 in a 4-step RACH process or MsgA in a 2-step RACH process with a common TA. In one aspect, the full TA that takes into account the UE-specific propagation delay can be set as the RAR window offset for the UE with location information. The UE can send Msg1 or MsgA with the full TA.

[0088] In one aspect, for the 2-step RACH procedure, the base station may blindly retransmit MsgB within a nominally 40ms RAR window to maintain reliable transmission of MsgB for NTN. This is because for NTN, large propagation delays may make HARQ-ACK retransmissions difficult within the RAR window. The MsgB-RNTI may be set equal to (1+s_id+14×t_id+14×80×f_id+14×80×8×ul_carrier_id+14×80×8×2). In one aspect, the number of blind retransmissions and / or the retransmission mode may depend on the PRACH reception conditions or the PUSCH reception conditions. In one aspect, the retransmission mode may be preconfigured.

[0089] In one aspect, due to the long propagation delay associated with NTN, the base station may extend the values ​​of K1 and K2, which determine the delay between uplink and downlink transmissions, to align with the time domain duplex (TDD) uplink-downlink configuration. For example, K1 may be the time gap in time slots between the PDSCH and the corresponding PUCCH with HARQ feedback. K1 may be indicated by the parameter "dl-DataToUL-ACK" in the information element "PUCCH-config". The maximum value of K1 may nominally be 15 time slots. K2 may be the time gap in time slots between DCI reception and the corresponding PUSCH scheduled by the DCI. K2 may be indicated by the parameter "k2" in the information element "PUSCH-TimeDomain ResourceAllocation". The maximum value of K2 may nominally be 32 time slots. The PUSCH and PUCCH transmission times scheduled by the DCI may be indicated by K1 and K2.

[0090] Figure 10 The timing relationship in NTN between a base station and a UE is shown using a timing advance adjustment to the UE based on the round trip propagation delay between the base station and the UE. In NTN, the additional offset K 偏移 Added to PUSCH or PUCCH transmission. For example, Figure 10 In the example, the one-way propagation delay between the UE and the base station is 4 slots, resulting in a round-trip propagation delay of 8 slots. Therefore, TA can be set to 8 slots. When the DCI for the uplink grant is in slot 0 and K2 is set to 2 by the DCI, the scheduled PUSCH may not be received by the base station until slot 10 due to the round-trip propagation delay of 8 slots. The additional offset K 偏移 Can be used to adjust PUSCH. However, according to the additional time offset K 偏移 , the resulting time slot for PUSCH or PUCCH transmission can be consistent with the downlink time slot. In one aspect, to align the delayed PUSCH or PUCCH transmission with the uplink time slot, the maximum value of K1 can be extended to 31 time slots and the maximum value of K2 can be extended to 64 time slots.

[0091] In one aspect, the base station may broadcast a new RAR window value to the UE to extend the RAR window size based on whether the satellite is a LEO, GEO, or other satellite. In one aspect, the base station may broadcast the new RAR window value using a system information block type 1 (SIB1). In one aspect, a new SIB1 information element may be used, or current information elements such as the "RACHConfigCommon IE" may be used by adding a new element for NTN.

[0092] In one aspect, the new RAR window value may be set to the same value. In one aspect, the RAR window value may be set based on the tracking area, which may be linked to the type of satellite being used. In one aspect, the RAR window value may be set based on the current load and network processing capabilities to ensure that other parameters are also appropriately scaled. This may include an estimate of how long the delay in a response from the network may be for MsgB in a 2-step RACH procedure or for Msg2 / 4 in a 4-step RACH procedure, and what actions the UE may take during the intermediate sleep durations.

[0093] In one aspect, the base station may use a paging message to multicast the new RAR window size value. Since paging messages are less frequent than SIB1 used for broadcast messages, the network may not be able to respond to significant spikes in network access traffic. The paging message size may need to be increased to include additional information of the new RAR window size value. However, network efficiency can be achieved because only the target UE of the paging message will utilize the additional information element, rather than all UEs in the NTN having their RACH behavior modified. In one aspect, the paging message can be restricted to downlink traffic only, so that UEs that can perform RACH procedures due to uplink traffic may not utilize the enhancement. In one aspect, any downlink page targeted to a UE can carry the new window size value, rather than using a multicast to all UEs. In one aspect, the paging message can be restricted to UEs that meet a specific International Mobile Subscriber Identity (IMSI).

[0094] Figure 11 is a data flow diagram illustrating an example of a method for a UE to transmit a PRACH preamble to a base station and receive a RAR message from the base station over an extended RAR window to perform a RACH procedure according to some aspects of the present disclosure.

[0095] At operation 1101 , the UE transmits a PRACH preamble to a base station of an NTN during a frame of a frame structure including a plurality of frames to request access to the NTN.

[0096] At operation 1103 , the UE receives a random access response RAR message from the base station during a RAR window, where the RAR window spans a plurality of frames of the frame structure.

[0097] At operation 1105, the UE determines whether the RAR message received from the base station is intended for the UE based on an indication in downlink control information (DCI) that schedules the RAR message.

[0098] Figure 12is a flow chart illustrating an example of a method for a base station to receive a PRACH preamble from a UE, determine an RNTI, and transmit a RAR to the UE over an extended RAR window based on the RNTI, according to some aspects of the present disclosure.

[0099] At operation 1201 , a base station receives a PRACH preamble from a UE during a frame of a frame structure including a plurality of frames to request access to an NTN.

[0100] At operation 1203, the base station determines an RNTI according to time-frequency resources of a frame for carrying a PRACH preamble.

[0101] At operation 1205, the base station transmits DCI scheduling a RAR message during a RAR window spanning multiple frames. The DCI includes an indication that allows the UE to determine that the RAR message is intended for the UE based on the RNTI and the frame number of the frame used to carry the PRACH preamble.

[0102] Aspects of the methods and apparatus described herein for enhancing RACH procedures in wireless communication networks can be implemented in a data processing system, for example, via a network computer, network server, tablet computer, smartphone, laptop computer, desktop computer, other consumer electronic device, or other data processing system. Specifically, the operations described are digital signal processing operations performed by a processor executing instructions stored in one or more memories. The processor can read the stored instructions from the memories and execute the instructions to perform the operations described. These memories represent examples of machine-readable, non-transitory storage media that can store or contain computer program instructions that, when executed, cause a data processing system to perform one or more of the methods described herein. The processor can be a processor in a local device, such as a smartphone, a processor in a remote server, or a distributed processing system of multiple processors in a local device and a remote server, wherein their respective memories contain portions of the instructions necessary to perform the operations described.

[0103] Although certain illustrative examples are described and shown in the drawings, it is to be understood that these examples are merely illustrative and not restrictive of the broader aspects of the invention, and that the present disclosure is not limited to the exact constructions and arrangements shown and described, since various other modifications may occur to one skilled in the art. Accordingly, the description is to be regarded as illustrative rather than restrictive.

Claims

1. A method performed by a base station in a non-terrestrial communication network, the method comprising: receiving, by the base station, a physical random access channel (PRACH) preamble from a user equipment (UE) during a frame of a frame structure including a plurality of frames to request access to the non-terrestrial communication network; determining, by the base station, a radio network temporary identifier (RNTI) based on time-frequency resources of the frame used to carry the PRACH preamble; transmitting, by the base station, downlink control information (DCI) scheduling a random access response (RAR) message during a RAR window spanning a plurality of the frames, wherein the DCI includes an indication enabling the UE to determine that the RAR message is intended for the UE based on the RNTI and a frame number of the frame carrying the PRACH preamble; as well as An information element including a maximum value of time slots indicating a delay between uplink transmission and downlink transmission is transmitted by the base station to the UE, wherein the maximum value includes 31 time slots.

2. The method of claim 1 , wherein transmitting the RAR message during the RAR window spanning multiple frames comprises: The RAR message is repeatedly transmitted for multiple frames of the RAR window.

3. The method of claim 2, wherein the number of frames used to transmit the RAR message is a function of channel conditions measured when receiving the PRACH preamble.

4. The method according to claim 2, further comprising: receiving, by the base station from the UE, uplink data carried on a second set of time-frequency resources following the PRACH preamble, And wherein the number of frames used to transmit the RAR message is a function of channel conditions measured when receiving the uplink data. The method of claim 2 , wherein the number and pattern of frames used to transmit the RAR message are preconfigured.

6. The method according to claim 1, further comprising: A number of frames spanning the RAR window are broadcast by the base station. The method of claim 6 , wherein the number of frames spanning the RAR window is a fixed value.

8. The method according to claim 6, further comprising: The number of frames spanning the RAR window is determined based on a coverage area of ​​the base station.

9. The method according to claim 6, further comprising: The number of frames spanning the RAR window is determined based on a processing load and processing capacity of the communication network.

10. The method of claim 1, wherein the RAR window spans two frames, and wherein the indication of the DCI identifies a frame number of a frame used to carry the PRACH preamble as an even frame or an odd frame.

11. The method of claim 1 , wherein the RAR window spans two frames, and wherein the RNTI is determined based on the time-frequency resources and an odd frame or an even frame of a frame number used to carry the PRACH preamble.

12. The method of claim 1 , wherein the RAR window spans two frames, and wherein a portion of a cyclic redundancy check (CRC) of the DCI is masked with the RNTI, wherein the masked portion of the CRC of the DCI is identified by an odd frame or an even frame of a frame number used to carry the PRACH preamble.

13. The method of claim 1, wherein a start of the RAR window is offset from an end of the PRACH preamble by a timing advance (TA) value, the TA value being suitable for aligning the frame structure between the UE and the base station.

14. The method of claim 1 , wherein receiving the PRACH preamble from the UE comprises: The PRACH preamble carried on the same time-frequency resource of multiple frames of the frame structure is repeatedly received from the UE.

15. A baseband processor of a base station, the baseband processor being configured to perform operations, the operations comprising: receiving a physical random access channel (PRACH) preamble from a user equipment (UE) of a non-terrestrial communication network during a frame of a frame structure including a plurality of frames to request access to the non-terrestrial communication network; determining a radio network temporary identifier (RNTI) based on time-frequency resources of the frame used to carry the PRACH preamble; transmitting, during a random access response (RAR) window spanning a plurality of the frames, downlink control information (DCI) scheduling a random access response (RAR) message, wherein the DCI includes an indication enabling the UE to determine that the RAR message is intended for the UE based on the RNTI and a frame number of the frame carrying the PRACH preamble; as well as An information element including a maximum value of time slots indicating a delay between uplink transmission and downlink transmission is transmitted by the base station to the UE, wherein the maximum value includes 31 time slots.

16. The baseband processor of claim 15 , wherein the operation of transmitting the RAR message during the RAR window spanning multiple frames comprises the following operations: The RAR message is repeatedly transmitted for multiple frames of the RAR window.

17. The baseband processor of claim 16, wherein the number of frames used to transmit the RAR message is a function of channel conditions measured when receiving the PRACH preamble.

18. The baseband processor of claim 16, wherein the operations further comprise: receiving uplink data carried on a second set of time-frequency resources following the PRACH preamble from the UE, And wherein the number of frames used to transmit the RAR message is a function of channel conditions measured when receiving the uplink data.

19. The baseband processor of claim 16, wherein the number and pattern of frames used to transmit the RAR message are preconfigured.

20. The baseband processor of claim 15, wherein the operations further comprise: Broadcast a certain number of frames spanning the RAR window.

21. The baseband processor of claim 20, wherein the number of frames spanning the RAR window is a fixed value.

22. The baseband processor of claim 20, wherein the operations further comprise: The number of frames spanning the RAR window is determined based on a coverage area of ​​the base station.

23. The baseband processor of claim 20, wherein the operations further comprise: The number of frames spanning the RAR window is determined based on a processing load and processing capacity of the communication network.

24. The baseband processor of claim 15, wherein the RAR window spans two frames, and wherein the indication of the DCI identifies a frame number of a frame used to carry the PRACH preamble as an even frame or an odd frame.

25. The baseband processor of claim 15, wherein the RAR window spans two frames, and wherein the RNTI is determined based on the time-frequency resources and an odd frame or an even frame of a frame number used to carry the PRACH preamble.

26. The baseband processor of claim 15 , wherein the RAR window spans two frames, and wherein a portion of a cyclic redundancy check (CRC) of the DCI is masked with the RNTI, wherein the masked portion of the CRC of the DCI is identified by an odd frame or an even frame of a frame number used to carry the PRACH preamble.

27. The baseband processor of claim 15, wherein a start of the RAR window is offset from an end of the PRACH preamble by a timing advance (TA) value, the TA value being suitable for aligning the frame structure between the UE and the base station.

28. The baseband processor of claim 15, wherein the operation of receiving the PRACH preamble from the UE comprises the following operations: The PRACH preamble carried on the same time-frequency resource of multiple frames of the frame structure is repeatedly received from the UE.

29. A base station device, comprising: at least one antenna; at least one radio, wherein the at least one radio is configured to communicate with a user equipment (UE) of a non-terrestrial communication network using the at least one antenna; as well as at least one processor coupled to the at least one radio, wherein the at least one processor is configured to perform operations comprising: receiving a physical random access channel (PRACH) preamble from the UE during a frame of a frame structure including a plurality of frames to request access to the non-terrestrial communication network; determining a radio network temporary identifier (RNTI) based on time-frequency resources of the frame used to carry the PRACH preamble; transmitting downlink control information (DCI) scheduling a random access response (RAR) message during a RAR window spanning multiple frames, wherein the DCI includes an indication allowing the UE to determine that the RAR message is intended for the UE based on the RNTI and a frame number of the frame used to carry the PRACH preamble; and An information element including a maximum value of a time gap indicating a delay between uplink transmission and downlink transmission is transmitted by the base station to the UE, wherein The maximum value includes 31 time slots.

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