RACH PROCEDURES FOR NON-TERRESTRIAL NETWORKS FOR USER EQUIPMENT - Patent application

Abstract

A method and system for enhancing the NR RACH procedure to accommodate non-terrestrial based networks (NTNs) are disclosed. The length of the RAR window may be extended. The NTN-RNTI associated with the time-frequency resource used for the PRACH preamble may be used to scramble the CRC of the DCI used to schedule the RAR message in the RAR window. The DCI content may include information about the associated PRACH preamble to assist the UE in distinguishing RAR messages triggered by PRACH preambles transmitted by different UEs from different frames. In one aspect, the NTN-RNTI may encode information on the system frame when the UE transmits the PRACH preamble. In another aspect, the RA-RNTI associated with the time-frequency resource used for the PRACH preamble transmitted from different frames may be used to scramble different subsets of the CRC of the DCI to assist the UE in decoding RAR messages intended for the UE.

Description

[Technical field]

[0001] The present disclosure relates to the field of wireless communications, and more particularly, to a method and system for enabling a wireless communications device to perform a Random Access Channel (RACH) procedure to a non-terrestrial based network. Other aspects are also described. [Background technology]

[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 fast-growing demand. For example, wireless communication networks such as 5G new radio (NR) systems may need to be deployed using satellites as part of a non-terrestrial based network (NTN). In one deployment scenario of an NTN, satellites, referred to as transparent satellites, may act as relay stations to link user devices with terrestrial base stations and 5G core networks by implementing a transparent payload. In another deployment scenario, satellites, referred to as regenerative satellites, may have on-board processing capabilities to perform the functions of a base station by implementing a regenerative payload between the user devices and the terrestrial 5G core network. Due to the wide coverage area of ​​the satellites and the long distance between the satellites and the terrestrial user devices, the difference in propagation delay between two user devices within a beam footprint is larger than that encountered in a strictly terrestrial based network. For example, for an NTN that deploys satellites in geostationary Earth orbit (GEO), the maximum delay difference between the nadir and edge of coverage may be 10.3 ms. For NTNs deploying satellites in low earth orbit (LEO), the maximum delay difference may be 3.12 ms and 3.18 ms for altitudes of 600 km and 1200 km, respectively.

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

[0004] The common search region, called the RAR window, in which the user devices search for the RARs may only be one frame in duration, which may not be long enough to accommodate the maximum delay difference of the user devices performing the RACH procedure in the NTN. If the RAR window is extended, there may be additional ambiguity for the user device to determine whether the RAR is intended for it, since the RAR window may include multiple RARs generated in response to multiple user devices with the same RA-RNTI that transmit PRACH using the same time-frequency resource in different system frames spanning the maximum delay difference. That is, multiple RARs in 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 complexities may arise for the RACH procedure in the NTN, including determining whether and how to delay the start of the RAR window due to the long maximum propagation delay. Summary of the Invention

[0005] A method and system are disclosed for enhancing the NR RACH procedure to accommodate non-terrestrial based networks (NTNs). Modifications may be made to the RACH procedure from a user equipment (UE) or base station, referred to as a "gNodeB" or "gNB" in 5G NR. The start of the RAR window and the length of the RAR window may be extended depending on the range of propagation delays (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 may be used to scramble the CRC of the downlink control information (DCI) format 1_0 used for the downlink assignment in the RAR. The DCI format 1_0 content may include information about the associated PRACH preamble to help the UE distinguish the RARs generated in response to PRACH preambles transmitted by different UEs from different system frames based on the same RA-RNTI. In one aspect, the NTN-RNTI may include information on the system frame when the UE transmits the PRACH preamble. In one aspect, the 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 the UE distinguish between RARs generated in response to different PRACH preambles.

[0006] In one aspect, the UE may perform blind retransmission of the PRACH preamble to indicate the extension of the RAR window. In one aspect, the UE may change the RAR window offset, which 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 retransmission of the RAR within the RAR window to improve transmission reliability for the NTN. The number of blind retransmissions and transmission patterns may depend on the PRACH reception condition, the uplink channel condition, or may be pre-configured. In one aspect, the gNB may extend the K1 and K2 values ​​that determine the delay between the uplink and downlink transmissions to align the Time Domain Duplex (TDD) uplink-downlink configuration due to the long propagation delay associated with the NTN. In one aspect, the gNB may broadcast or multicast the RAR window size extension value to the UEs based on the satellite's orbital altitude.

[0008] The above summary does not provide an exhaustive list of all aspects of the present disclosure. Aspects of the present disclosure are believed to include all systems and methods that can be implemented from all suitable combinations of the various aspects summarized above, as well as those disclosed in the Detailed Description below, and particularly those pointed out in the claims filed together with this application. Such combinations have certain advantages not specifically described in the above summary.

[0009] Some aspects of the disclosure herein are illustrated by way of example and not by way of limitation in the figures of the accompanying drawings in which like reference symbols indicate like elements. It should be noted that references to "an" or "one" aspect of the disclosure are not necessarily to the same aspect, but they do mean at least one. Also, for the sake of brevity and reducing the total number of figures, a given figure may be used to illustrate features of multiple aspects of the disclosure, and not all elements in the figure may be required for a given aspect. [Brief description of the drawings]

[0010] [Figure 1] 1 illustrates an example wireless communication system in accordance with certain aspects of the present disclosure. [Diagram 2]1 illustrates a base station (BS) in communication with a user equipment (UE) device, according to certain aspects of the present disclosure. [Diagram 3] 1 illustrates an example block diagram of a UE in accordance with certain aspects of the present disclosure. [Figure 4] 1 illustrates an example block diagram of a BS according to certain aspects of the present disclosure. [Diagram 5] FIG. 1 illustrates an example block diagram of a cellular communication circuit in accordance with some aspects of the disclosure. [Figure 6] 1 illustrates a DCI field-based RAR window size extension in accordance with certain aspects of the present disclosure. [Figure 7] 1 illustrates an RNTI-based RAR window size extension in accordance with certain aspects of the present disclosure. [Figure 8] 1 illustrates PRACH blind retransmission by a UE across multiple frame numbers to indicate an extension of the RAR window size in accordance with certain aspects of the present disclosure. [Figure 9] 1 illustrates the use of RA-RNTI to mask different positions of DCI in accordance with certain aspects of the present disclosure. [Figure 10] 1 shows a timing relationship in an NTN between a base station and a UE using timing advance adjustment for the UE based on round-trip propagation delay between the base station and the UE. [Figure 11] 1 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 an RAR message from the base station over an extended RAR window to perform a RACH procedure in accordance with certain aspects of the present disclosure. [Figure 12] FIG. 2 is a flow diagram illustrating an example of a method for a base station to receive a PRACH preamble from a UE, determine an RNTI, and send an RAR to the UE based on the RNTI over an extended RAR window, in accordance with certain aspects of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Techniques are disclosed for enhancing the NR RACH procedure to accommodate non-terrestrial based networks (NTNs) or other networks with long propagation delays. The start of the RAR window and the length of the RAR window used for the RACH procedure can be extended depending on the range of propagation delays (e.g., LEO or GEO satellites). The RNTI associated with the time-frequency resource used for the PRACH preamble and the frame number of the transmission of the PRACH by the UE can be used to scramble the CRC of the DCI format 1_0 in the RAR to assist the UE in distinguishing an RAR intended for the UE from an RAR generated in response to a PRACH preamble transmitted by another UE during a different system frame.

[0012] In one aspect, a method for accessing an NTN by a UE is disclosed. The method includes the UE transmitting a PRACH preamble to a base station of the NTN, such as a 5G NR gNB, during a frame to request access to the NTN. The frame may be part of a frame structure including several frames. The method also includes the UE receiving an RAR message from the base station during an RAR window. The RAR window may span several frames of the frame structure. The method further includes the UE determining whether the RAR message received from the base station is intended for the UE based on an indication in a downlink control information (DCI) that schedules the RAR message.

[0013] In one aspect, a method is disclosed for granting access to an NTN by a base station, such as a 5G NR gNB, upon request from a UE. The method includes the base station receiving a PRACH preamble from the UE during a frame to request access to the NTN. The method also includes the base station determining an RNTI from a time-frequency resource of the frame used to carry the PRACH preamble. The method further includes the base station transmitting an RAR message during an RAR window spanning several frames. The RAR message is scheduled by a DCI that includes an indication to enable 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.

[0014] In the following description, numerous specific details are set forth. However, it is understood that aspects of the disclosure herein may be practiced without these specific details. In other instances, well-known circuits, structures and techniques have not been shown in detail in order not to obscure an understanding of this specification.

[0015] The terms used herein are for the purpose of describing particular embodiments only and are not intended to limit the embodiments of the present disclosure. Spatially relative terms such as "below," "under," "lower," "above," and the like may be used herein to describe the relationship of one element or feature to another element or feature as shown in the figures for ease of description. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, an element described as "below" or "below" the other element or feature would then be oriented "above" the other element or feature. Thus, the exemplary term "below" can encompass both an up and down orientation. The device may otherwise be oriented in other ways (e.g., rotated 90 degrees or rotated in other directions) and the spatially relative descriptors used herein would be interpreted accordingly.

[0016] As used herein, the singular forms "a," "an," and "the" are intended to include the plural forms unless the context indicates otherwise. It will be further understood that the terms "comprises" and "comprising" specify the presence of stated features, steps, operations, elements, or components, but do not exclude the presence or addition of one or more other features, steps, operations, elements, components, or groups thereof.

[0017] The terms "or" and "and / or," as used herein, should be interpreted to include or contemplate 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." Exceptions to this definition occur only when combinations of elements, features, steps or acts are in some way inherently mutually exclusive.

[0018] 1 illustrates a simplified exemplary wireless communication system according to some aspects. It should be noted that the system of FIG. 1 is merely one example of a possible system, and that the features of the present disclosure may be implemented in any of a variety of systems, as desired.

[0019] As shown in the figure, the exemplary wireless communication system includes a base station 102A that communicates over a transmission medium with one or more user devices 106A, 106B, etc. through 106N. Each of the user devices may be referred to herein as a "user equipment" (UE). Accordingly, the user devices 106 are referred to as UEs or UE devices.

[0020] The base station (BS) 102A may be a base transceiver station (BTS) or a cell site ("cellular base station") and may include hardware to enable wireless communication with the UEs 106A-106N. In one aspect, the base station 102A may be deployed as a satellite, referred to as a regenerative satellite, that carries on-board processing capabilities to perform the functions of a base station to implement regenerative payloads between the UEs and the terrestrial core network.

[0021] A 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 referred to as wireless communication technologies or standards, such as GSM, UMTS (e.g., associated with a WCDMA or TD-SCDMA air interface), LTE, LTE-Advanced (LTE-A), 5G New Radio (5G NR), HSPA, 3GPP2 CDMA2000 (e.g., 1xRTT, 1xEV-DO, HRPD, eHRPD). Note that if the base station 102A is implemented in the context of LTE, it may be referred to interchangeably as an "eNodeB" or "eNB." Note that if the base station 102A is implemented in the context of 5G NR, it may be referred to interchangeably as a "gNodeB" or "gNB."

[0022] As shown, the base station 102A may also be equipped to communicate with a network 100 (e.g., a cellular service provider's core network, a communications network such as the Public Switched Telephone Network (PSTN), and / or the Internet, among other possibilities). Thus, the base station 102A may facilitate communications between user devices and / or between the user devices and the network 100. In particular, the cellular base station 102A may provide various communication capabilities to the UE 106, such as voice, SMS, and / or data services.

[0023] Base station 102A and other similar base stations (such as base stations 102B...102N) operating according to the same or different cellular communication standards may thus be provided as a network of cells that can provide continuous or near-continuous overlapping services to UEs 106A-N and similar devices across a geographic area via one or more cellular communication standards.

[0024] Thus, as shown in FIG. 1, the base station 102A may function as a "serving cell" for the UEs 106A-N, and each UE 106 may also be capable of receiving signals from (where possible within range of) one or more other cells (which may be provided by the 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 communication between user devices and / or between the user devices and the network 100. Such cells may include "macro" cells, "micro" cells, "pico" cells, and / or cells providing various other granularity of coverage area size. For example, the 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 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 the neighboring cell base stations 102B-N to support position determination of the UE 106.

[0025] In some aspects, the base station 102A may be a next generation base station, e.g., a 5G New Radio (5G NR) base station, or "gNB." In some aspects, the gNB may be connected to a legacy Evolved Packet Core (EPC) network and / or an NR Core (NRC) network. In addition, a gNB cell may include one or more Transition and Reception Points (TRPs). In addition, a UE capable of operating according to 5G NR may be connected to one or more TRPs in one or more gNBs.

[0026] It should be noted that the UE 106 may be capable of communicating using multiple wireless communication standards. For example, the UE 106 may be configured to communicate using at least one cellular communication protocol (e.g., GSM, UMTS (e.g., associated with a WCDMA or TD-SCDMA air interface), LTE, LTE-A, 5G NR, HSPA, 3GPP2 CDMA2000 (e.g., 1xRTT, 1xEV-DO, HRPD, eHRPD), etc.) in addition to wireless networking (e.g., Wi-Fi) and / or peer-to-peer wireless communication protocols (e.g., Bluetooth, Wi-Fi peer-to-peer, etc.). The UE 106 may also or alternatively be configured to communicate using one or more Global Navigation Satellite Systems (GNSS, e.g., 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, as appropriate. Other combinations of wireless communication standards (including three or more wireless communication standards) are also possible.

[0027] 2 illustrates a user equipment 106 (e.g., one of devices 106A-106N) in communication with a base station 102, according to some aspects. The UE 106 may be a device having cellular communication capabilities, such as a mobile phone, a handheld device, a computer or tablet, or virtually any type of wireless device.

[0028] 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 additionally, the UE 106 may include a programmable hardware element, such as an FPGA (field programmable gate array), configured to perform any of the embodiments of the methods described herein, or any portion of any of the methods described herein.

[0029] 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), LTE or 5G NR using a single shared radio, and / or GSM, 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) to perform wireless communication. In general, a radio may include any combination of a baseband processor, analog 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, a radio may implement one or more receive and transmit chains using the hardware described above. For example, the UE 106 may share one or more portions of the receive and / or transmit chains between multiple wireless communication technologies such as those described above.

[0030] In some aspects, the UE 106 may include a separate transmit and / or receive chain (e.g., including separate antennas and other radio components) for each wireless communication protocol it is configured to communicate using. As a further possibility, the UE 106 may include one or more radios shared among multiple wireless communication protocols and one or more radios used only by a single wireless communication protocol. For example, the UE 106 may include a shared radio for communicating using either LTE or 5G NR (or LTE or 1xRTT, or LTE or GSM) and a separate radio for communicating using each of Wi-Fi and Bluetooth. Other configurations are possible.

[0031] FIG. 3 illustrates an exemplary simplified block diagram of a communication device 106 according to some aspects. It should be noted that the communication device block diagram of FIG. 3 is just one example of a possible communication device. According to aspects, 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, and / or a combination of devices, among other devices. As shown in the figure, the communication device 106 may include a set of components 300 configured to perform core functions. For example, this set of components may be implemented as a System On Chip (SOC) that may include portions for various purposes. Alternatively, this set of components 300 may be implemented as separate components or groups of components for various purposes. The set of components 300 may be (e.g., communicatively coupled, directly or indirectly) to various other circuits of the communication device 106.

[0032] For example, the communication device 106 may include various types of memory (including, for example, NAND flash 310), input / output interfaces such as connector I / F 320 (e.g., for connecting to a computer system, a dock, a charging station, input devices such as a microphone, camera, keyboard, output devices such as a speaker, etc.), a display 360 that may be integrated with the communication device 106 or may be external to the communication device 106, cellular communication circuitry 330 for 5G NR, LTE, GSM, etc., and near-medium range wireless communication circuitry 329 (e.g., Bluetooth and WLAN circuitry). In some aspects, the communication device 106 may include wired communication circuitry (not shown), such as a network interface card for Ethernet, for example.

[0033] The cellular communication circuitry 330 may be communicatively coupled (e.g., communicatively, directly or indirectly) to one or more antennas, such as antennas 335 and 336, as shown. The near-medium range wireless communication circuitry 329 may also be communicatively coupled (e.g., communicatively, directly or indirectly) to one or more antennas, such as antennas 337 and 338, as shown. Alternatively, the near-medium range wireless communication circuitry 329 may be communicatively coupled (e.g., communicatively, directly or indirectly) to antennas 335 and 336 in addition to or instead of being communicatively coupled (e.g., communicatively, directly or indirectly) to antennas 337 and 338. The near-medium range wireless communication circuitry 329 and / or the 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.

[0034] In some aspects, as described further below, the cellular communication circuitry 330 may include dedicated receive chains (e.g., a first receive chain for LTE and a second receive chain for 5G NR) for multiple RATs (e.g., including a dedicated processor and / or radio and / or communicatively coupled, directly or indirectly, to the dedicated processor and / or radio). Additionally, in some aspects, the cellular communication circuitry 330 may include a single transmit chain that may be switched between radios dedicated to a particular RAT. For example, a first radio may be dedicated to a first RAT, e.g., LTE, and may communicate with a dedicated receive chain and a transmit chain shared with an additional radio, e.g., a second radio, which may be dedicated to a second RAT, e.g., 5G NR, and may communicate with a dedicated receive chain and a shared transmit chain.

[0035] Communications device 106 may also include and / or be configured for use with one or more user interface elements, which may include any of a variety of elements, such as a display 360 (which may be a touchscreen display), a keyboard (which may be a separate keyboard or may be implemented as part of the touchscreen display), a mouse, a microphone and / or speaker, 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.

[0036] The communication device 106 may further include one or more smart cards 345 including SIM (Subscriber Identity Module) functionality, such as one or more UICC(s) (Universal Integrated Circuit Card) cards 345 .

[0037] As shown, the SOC 300 may include a processor(s) 302 that may execute program instructions for the communication device 106 and a display circuit 304, perform graphic processing, and provide display signals to a display 360. The processor(s) 302 may be coupled to a memory management unit (MMU) 340 that may be configured to receive addresses from the processor(s) 302 and translate those addresses to locations in memory (e.g., memory 306, read only memory (ROM) 350, NAND flash memory 310) and / or other circuits or devices, such as the display circuit 304, the near field 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(s) 302.

[0038] As described above, the communication device 106 may be configured to communicate using wireless and / or wired communication circuitry. The communication device 106 may be configured to transmit a request to attach to a first network node operating according to a first RAT and transmit an indication that the wireless device is capable of maintaining substantially simultaneous connections with the first network node and a second network node operating according to a second RAT. The wireless device may also be configured to transmit a request to attach to a second network node. The request may include an indication that the wireless device is capable of maintaining substantially simultaneous connections with the first network node and the second network node. Furthermore, the wireless device may be configured to receive an indication that dual connectivity with the first network node and the second network node has been established.

[0039] As described herein, the communication device 106 may include hardware and software components to implement the above features for time division multiplexing UL data for non-standalone (NSA) NR operation. The processor 302 of the communication device 106 may be configured to implement some or all of the features described herein, for example, by executing program instructions stored in a memory medium (e.g., a non-transitory computer-readable memory medium). Alternatively (or in addition), the processor 302 may be configured as a programmable hardware element, such as a field programmable gate array (FPGA), or as an application specific integrated circuit (ASIC). Alternatively (or in addition), the processor 302 of the communication device 106 may be configured to implement some or all of the features described herein in conjunction with one or more of the other components 300, 304, 306, 310, 320, 329, 330, 340, 345, 350, 360.

[0040] Additionally, as described herein, the processor 302 may include one or more processing elements. Thus, the processor 302 may include one or more integrated circuits (ICs) configured to perform the functions of the processor 302. Additionally, each integrated circuit may include a circuit (e.g., a first circuit, a second circuit, etc.) configured to perform the functions of the processor(s) 302.

[0041] Further, as described herein, the cellular communication circuit 330 and the near field communication circuit 329 may each include one or more processing elements. In other words, one or more processing elements may be included in the cellular communication circuit 330, and similarly, one or more processing elements may be included in the near field communication circuit 329. Thus, the cellular communication circuit 330 may include one or more integrated circuits (ICs) configured to perform the functions of the cellular communication circuit 330. In addition, each integrated circuit may include a circuit (e.g., a first circuit, a second circuit, etc.) configured to perform the functions of the cellular communication circuit 230. Similarly, the near field communication circuit 329 may include one or more ICs configured to perform the functions of the near field communication circuit 32. In addition, each integrated circuit may include a circuit (e.g., a first circuit, a second circuit, etc.) configured to perform the functions of the near field communication circuit 329.

[0042] 4 illustrates an example block diagram of a base station 102 according to some aspects. It should be noted that the base station of FIG. 4 is merely one example of a possible base station. As shown, the base station 102 may include a processor(s) 404 that may execute program instructions for the base station 102. The processor(s) 404 may also be coupled to a memory management unit (MMU) 440 that may be configured to receive addresses from the processor(s) 404 and translate those addresses to locations in memory (e.g., memory 460 and read only memory (ROM) 450) or other circuits or devices.

[0043] 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 to multiple devices, such as the UE device 106, as described above in FIGs.

[0044] Network port 470 (or additional network ports) may also or alternatively be configured to couple to a cellular network, such as, for example, a core network of a cellular service provider. The core network may provide mobility-related services and / or other services to multiple devices, such as UE device 106. In some cases, network port 470 may be coupled to a telephone network via the core network and / or the core network may provide telephone services (e.g., among other UE devices serviced by the cellular service provider).

[0045] In some aspects, the base station 102 may be a next generation base station, e.g., a 5G New Radio (5G NR) base station, or "gNB." In such aspects, the base station 102 may be connected to a legacy evolved packet core (EPC) network and / or an NR core (NRC) network. In addition, the base station 102 may be considered a 5G NR cell and may include one or more transmission / reception points (TRPs). In addition, a UE capable of operating according to 5G NR may be connected to one or more TRPs in one or more gNBs.

[0046] 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 operate 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, etc.

[0047] The base station 102 may be configured to communicate wirelessly using multiple wireless communication standards. In some cases, the base station 102 may include multiple radios that may enable the base station 102 to communicate according to multiple wireless communication technologies. For example, in one possibility, the base station 102 may include an LTE radio for performing communications according to LTE and a 5G NR radio for performing communications according to 5G NR. In such a case, the base station 102 may be capable of operating as both an LTE base station and a 5G NR base station. In another possibility, the base station 102 may include a multi-mode radio that may perform communications 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 described further herein, the BS 102 may include hardware and software components implementing or supporting the implementation of features described herein. The processor 404 of the base station 102 may be configured to implement or support some or all of the methods described herein, for example, by executing program instructions stored in 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), the processor 404 of the BS 102, together with one or more of the other components 430, 432, 434, 440, 450, 460, 470, may be configured to implement or support some or all of the features described herein.

[0048] Additionally, as described herein, the processor(s) 404 may be comprised of one or more processing elements. In other words, one or more processing elements may be included within the processor(s) 404. Thus, the processor(s) 404 may include one or more integrated circuits (ICs) configured to perform the functions of the processor(s) 404. Additionally, each integrated circuit may include a circuit (e.g., a first circuit, a second circuit, etc.) configured to perform the functions of the processor(s) 404.

[0049] Further, as described herein, the radio 430 may be comprised of one or more processing elements. In other words, the one or more processing elements may be included within the radio 430. Thus, the radio 430 may include one or more integrated circuits (ICs) configured to perform the functions of the radio 430. In addition, each integrated circuit may include circuitry (e.g., a first circuit, a second circuit, etc.) configured to perform the functions of the radio 430.

[0050] FIG. 5 illustrates an exemplary simplified block diagram of cellular communication circuitry according to some aspects. It should be noted that the block diagram of the cellular communication circuitry in FIG. 5 is merely one example of possible cellular communication circuitry. According to aspects, the cellular communication circuitry 330 may be included within a communication device, such as the communication device 106 described above. As noted 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, and / or a combination of devices, among other devices.

[0051] The cellular communication circuitry 330 may be (e.g., communicatively coupled, directly or indirectly) to one or more antennas, such as antennas 335a-b and 336, as shown (in FIG. 3). In some aspects, the cellular communication circuitry 330 may include dedicated receive chains (e.g., a first receive chain for LTE and a second receive chain for 5G NR) for multiple RATs (e.g., including a dedicated processor and / or radio and / or communicatively coupled, directly or indirectly to a dedicated processor and / or radio). For example, as shown in FIG. 5, the cellular communication circuitry 330 may include a modem 510 and a modem 520. The modem 510 may be configured for communication according to a first RAT, such as, for example, LTE or LTE-A, and the modem 520 may be configured for communication according to a second RAT, such as, for example, 5G NR.

[0052] 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 wireless 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 wireless signals via an antenna 335a.

[0053] 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 wireless 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 wireless signals via the antenna 335b.

[0054] In some aspects, the switch 570 may couple the transmit circuitry 534 to an uplink (UL) front end 572. Additionally, 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 wireless signals via the antenna 336. Thus, when the cellular communication circuitry 330 receives an instruction to transmit according to a first RAT (e.g., as supported via the modem 510), the switch 570 may be switched to a first state that enables the modem 510 to transmit signals according to the first RAT (e.g., via a transmit chain that includes 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., as supported via the modem 520), the switch 570 may be switched to a second state that enables the modem 520 to transmit signals according to the second RAT (e.g., via a transmit chain that includes the transmit circuitry 544 and the UL front end 572).

[0055] As described herein, the modem 510 may include hardware and software components for implementing the above functions or for time division multiplexing UL data for NSA NR operations, as well as various other techniques described herein. The processor 512 may be configured to implement some or all of the features described herein, for example, by executing program instructions stored in a memory medium (e.g., a non-transitory computer-readable memory medium). Alternatively (or in addition), the processor 512 may be configured as a programmable hardware element, such as a field programmable gate array (FPGA), or as an application specific integrated circuit (ASIC). Alternatively (or in addition), the processor 512 may be configured to implement some or all of the features described herein in conjunction with one or more of the other components 530, 532, 534, 550, 570, 572, 335, and 336.

[0056] Additionally, as described herein, the processor 512 may include one or more processing elements. Thus, the processor 512 may include one or more integrated circuits (ICs) configured to perform the functions of the processor 512. Additionally, each integrated circuit may include a circuit (e.g., a first circuit, a second circuit, etc.) configured to perform the functions of the processor 512.

[0057] As described herein, the modem 520 may include hardware and software components implementing the above features, as well as various other techniques described herein, for time division multiplexing UL data for NSA NR operation. The processor 522 may be configured to implement some or all of the features described herein, for example, by executing program instructions stored in a memory medium (e.g., a non-transitory computer-readable memory medium). Alternatively (or in addition), the processor 522 may be configured as a programmable hardware element, such as a field programmable gate array (FPGA), or as an application specific integrated circuit (ASIC). Alternatively (or in addition), the processor 522 may be configured to implement some or all of the features described herein in conjunction with one or more of the other components 540, 542, 544, 550, 570, 572, 335, and 336.

[0058] Additionally, 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. Additionally, each integrated circuit may include circuitry (e.g., a first circuit, a second circuit, etc.) configured to perform the functions of processor 522.

[0059] In 5G NR, a UE may initiate a RACH procedure to gain initial access to the network. In a four-step contention-based RACH procedure, the UE may transmit a PRACH to the base station in a first step. The PRACH, which may also be referred to as Msg1 or a PRACH preamble, may include one of 64 preambles (long or short preambles) transmitted in a RACH occasion (RO). The UE may power ramp the PRACH after each failed PRACH transmission. The UE may transmit the PRACH in a frame using a time-frequency resource uniquely associated with the UE's RA-RNTI. For example, the RA-RNTI may be determined from an index of the first orthogonal frequency division multiplexing (OFDM) symbol of the PRACH, an index of the first slot of the PRACH in the transmitted frame, an index of the PRACH in the frequency domain, etc. Two or more UEs may be transmitting the same PRACH on the same time-frequency resource in a frame.

[0060] The UE may transmit the PRACH using a Timing Advance (TA) adjustment to account for the 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 may autonomously obtain a UE-specific TA based on its known location and satellite ephemeris history. Alternatively, the base station may broadcast a common TA based on a reference point in a satellite beam or cell. The base station may also transmit a UE-specific differential TA to the UE based on a network indication for the UE to derive the total TA as the sum of the common TA and the differential TA.

[0061] In the second step of the RACH procedure, in response to the PRACH from the UE, the base station may transmit an RAR, which may also be referred to as Msg2, or an RAR message. The base station may derive the RA-RNTI of the user device transmitting the PRACH from the time-frequency resource carrying the PRACH. The RAR may be scheduled by DCI format 1_0 carried on a 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 within a common search area of ​​the RAR window. The RAR may also include a medium access control physical data unit (MAC PDU) carried on a physical downlink shared channel (PDSCH) specified by DCI format 1_0. The subhead of the MAC PDU may include a 6-bit random access preamble ID (RAPID) or a 4-bit backoff 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), which may be used by the UE for the remainder of the RACH procedure.

[0062] The UEs may search for the RAR during a common search area of ​​the RAR window. The RAR window may start after Msg1 and may last up to one frame, or 10 ms. Since two or more UEs may be transmitting the same PRACH on the same time-frequency resource in a frame, multiple UEs may attempt to decode the DCI format 1_0 of the PDCCH with the CRC scrambled by the same RA-RNTI. Thus, multiple UEs may decode the DCI format 1_0, obtain the MAC PDU of the RAR from the PDSCH specified by the DCI format 1_0, and compete for access to the network.

[0063] In the third step of the RACH procedure, after the UE receives the RAR, the UE may transmit a control element, which may be referred to as Msg3, on the physical uplink shared channel (PUSCH) allocated by the RAR. The UE may use the TC-RNTI received in the RAR to scramble Msg3. Msg3 may include the Cell-RNTI (C-RNTI), a unique identification of the UE used by the base station to assign the UE with an uplink grant, a downlink assignment, etc. If the base station cannot decode Msg3, the base station may reschedule a retransmission of Msg3 using DCI format 0_0 of the PDCCH with a CRC scrambled by the TC-RNTI.

[0064] In the fourth step of the RACH procedure, after the base station decodes Msg3, the base station may transmit a contention resolution identity MAC control element in Msg4. Msg4 may be carried on the PDSCH specified by DCI format 1_0 of the PDCCH with a CRC scrambled by the TC-RNTI. The TC-RNTI may win the contention and be promoted to the C-RNTI for UEs that do not yet have a C-RNTI. If the UE successfully completes the RACH procedure and already has a C-RNTI, the UE may resume using its C-RNTI and may discard the TC-RNTI received in the RAR. After the UE decodes Msg4, the UE may transmit a Hybrid Automatic Repeat Request Acknowledgement (HARQ-ACK) signal on the PUCCH.

[0065] To facilitate the RACH procedure, 5G NR introduces a two-step RACH procedure. In the first step of the two-step RACH procedure, the UE may transmit a MsgA including a PRACH and a PUSCH. The RACH occasion (RO) used for the PRACH and the PUSCH occasion (PO) used for the PUSCH may have fixed resource mapping. The PO map does not overlap with the RO. The RO configured for the two-step RACH may be separate from or shared with the RO configured for the four-step RACH. The PUSCH may include 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.

[0066] In the second step of the two-step RACH procedure, in response to receiving MsgA, the base station may transmit a RAR, called MsgB. MsgB may include PDCCH and PDSCH, including either a normal RAR MAC if the PUSCH was successfully received by the base station, or a fallback RAR MAC otherwise. The normal RAR MAC may include a contention resolution ID, TA, C-RNTI, etc. The fallback RAR Mac may include a backoff indicator for the UE to retransmit the PRACH and PUSCH of MsgA. The UE may search for MsgB within the RAR window. The RAR window may start after the MsgA PUSCH transmission and may last up to 4 frames, i.e., 40 ms.

[0067] The PDCCH of MsgB may include DCI format 1_0 with CRC scrambled by C-RNTI if the UE is in connected mode. Otherwise, the CRC of DCI format 1_0 is scrambled by MsgB-RNTI. The UE may attempt to decode DCI format 1_0 specifying a PDSCH with normal RAR MAC or fallback RAR MAC using MsgB-RNTI or C-RNTI within the RAR window.

[0068] FIG. 6 illustrates a DCI field-based RAR window size extension according to one embodiment of the present disclosure. The RAR window size may be extended for a four-step RACH procedure depending on whether the satellites in the NTN are LEO or GEO satellites. For LEO satellites, the maximum delay difference may be 3.12 ms and 3.18 ms for satellite altitudes of 600 km and 1200 km, respectively. Since twice the maximum delay difference 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 delay difference between the nadir and edge of coverage may be 10.3 ms. Since twice the maximum delay difference is close to 20 ms, i.e., two frames, an extension of the RAR window size may be required.

[0069] In one aspect, if the RAR window size is extended to 20 ms for GEO satellites, the DCI field may indicate the RAR window size extension. In the Msg2 transmission, the CRC of the DCI format 1_0 may be scrambled by a new NTN-RNTI in the common search space. Similar to the RA-RNTI, the NTN-RNTI may be determined from the time-frequency resource used to transmit the PRACH in the RACH occasion. In one aspect, the NTN-RNTI may be determined from 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 of the two-step RACH procedure. For example, 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 may then be 35841 to 53760 to avoid value conflicts with the range of RA-RNTI from 1 to 17920 and the range of MsgB-RNTI from 17921 to 35840. DCI format 1_0 further comprises a field to indicate the least significant bit of the system frame number (SFN) when the PRACH that triggers DCI format 1_0 is transmitted.

[0070] The UE has knowledge of the NTN-RNTI and SFN when the PRACH is transmitted. Thus, the UE can decode the DCI format 1_0 using the NTN-RNTI. The UE may also verify that a bit field in the DCI format 1_0 indicating the last bit of the SFN associated with the PRACH that triggers the DCI format 1_0 matches the last bit of the SFN when the UE transmits the PRACH. Thus, the UE may determine whether the RAR received during the extended RAR window is intended for the UE as distinguished from an RAR intended for another UE that uses the same time-frequency resource but transmits a PRACH on a different frame. For example, if a UE transmits a PRACH during a frame with SFNx (e.g., an even frame number) and another UE transmits the same PRACH during a subsequent frame with SFNx+1 (e.g., an odd frame number) using the same time-frequency resource, the CRC of the DCI format 1_0 of the RAR of both UEs may be scrambled by the same NTN-RNTI in a common search space. However, the two DCI formats 1_0 may include a field for the DCI indicating that the PRACH triggering the two RARs was transmitted on two consecutive frames. A UE transmitting a PRACH on SFNx may 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 may receive the correct RARs.

[0071] FIG. 7 illustrates an RNTI-based RAR window size extension according to another aspect of the present disclosure. Again, the RAR window size is extended to 20 ms for GEO satellites. In Msg2 transmission, the CRC of DCI format 1_0 may be scrambled by a new NTN-RNTI within the common search space. However, unlike the DCI field-based RAR window size extension of FIG. 6, the NTN-RNTI here may encode the least significant bit of the SFN when the PRACH triggering the DCI field is transmitted. For example, the NTN_RNTI may be equal to (1+s_id+14xt_id+14x80xf_id+14x80x8xul_carrier_id+14x80x8x4x (SFN mode 2)). As a result, when the RACH occasion is in an even-numbered SFN, the NTN-RNTI is reduced to the RA-RNTI. On the other hand, if the RACH occasion is in an odd-numbered SFN, the NTN-RNTI uses a new value that is different from the RA-RNTI. This avoids value conflicts with the MsgB-RNTI, but the value of the RA-RNTI is reused. That is, the NTN-RNTI range may be set to [1, 17920] (set 1) for even-numbered SFNs and [35841, 53760] (set 2) for odd-numbered SFNs.

[0072] In one aspect, to reuse the value range of MsgB-RNTI, NTN_RNTI may be equal to (1+s_id+14xt_id+14x80xf_id+14x80x8xul_carrier_id+14x80x8x2x(SFN mode 2)). Then, the range of NTN-RNTI may be [1, 35840] or [1, 17920] for set 1 and [17921, 35840] for set 2. Also, unlike the DCI field-based RAR window size extension of Figure 6, DCI format 1_0 no longer indicates the least significant bit of the system frame number (SFN) when the PRACH that triggers DCI format 1_0 is transmitted. The UE can calculate NTN_RNTI based on the time-frequency resource of the RACH occasion and the SFN when the UE 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 SFNx, and another UE transmits the same PRACH during a subsequent frame with SFNx+1 using the same time-frequency resource, the CRCs of the DCI format 1_0 of the RARs of both UEs can be scrambled by different NTN-RNTIs in a common search space. Then, the UE transmitting the PRACH on SFNx can decode the DCI format 1_0 using its corresponding NTN-RNTI to determine that the DCI format 1_0 is intended for the UE, so that the UE can receive the correct RAR.

[0073] FIG. 8 illustrates PRACH blind retransmissions by a UE across multiple frame numbers to illustrate the extension of the RAR window size according to another aspect of the disclosure. Again, the RAR window size is extended to 20 ms for GEO satellites. In Msg1 transmission, the UE transmits multiple (e.g., two) PRACH transmissions in the same RACH occasion (using the same time-frequency resource) that are repeated across multiple frames. In an aspect, the transmit power of the PRACH retransmissions may be increased incrementally or may remain the same. After the retransmission, the preamble power ramping counter may be increased by one or may be increased by the number of PRACH blind retransmissions. The same RA-RNTI is obtained from each of the PRACH retransmissions. That is, the RA-RNTI may be equal to (1+s_id+14xt_id+14x80xf_id+14x80x8xul_carrier_id). In one aspect, a RACH occasion is paired between multiple (e.g., two) consecutive frames. For example, each UE may transmit a PRACH over two consecutive frames, a first PRACH in an even SFN (SFNx) and a second PRACH in an odd SFN (SFNx+1). This avoids one-frame staggered PRACH transmissions from two different UEs. Each UE may wait within its own RAR window of 20 ms to receive a RAR message by decoding DCI format 1_0 with its unique RA-RNTI.

[0074] FIG. 9 illustrates the use of RA-RNTI to mask different positions of DCI CRC according to another aspect of the present disclosure. Again, the RAR window size is extended to 20 ms for GEO satellites. In Msg2 transmission, different subsets of CRC of DCI format 1_0 may be scrambled by RA-RNTI in a common search space depending on the frame number when the PRACH triggering DCI format 1_0 is transmitted. RA-RNTI may be equal to (1+s_id+14xt_id+14x80xf_id+14x80x8xul_carrier_id). DCI format 1_0 corresponds to PRACH transmitted using RACH occasions in even-numbered SFNs when the last 16 bits of CRC of DCI format 1_0 are scrambled by RA-RNTI, also referred to as masking the last 16 CRC bits of DCI format 1_0 with RA-RNTI. When 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 CRC bits of DCI format 1_0 with the RA-RNTI, the RAR corresponds to a PRACH transmitted using a RACH occasion in an odd-numbered SFN.

[0075] The UE can calculate the RA-RNTI based on the time-frequency resource of that RACH occasion and can determine the SFN when transmitting the PRACH. The UE can use the least significant bit 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 SFNx and another UE transmits the same PRACH during a subsequent frame with SFNx+1 using the same time-frequency resource, different subsets of the CRC of DCI format 1_0 of the RARs of the two UEs may be scrambled by the same RA-RNTI in a common search space. Then, the UE transmitting the PRACH on SFNx can 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.

[0076] In one aspect, the RAR window offset for the RACH procedure may be modified. The RAR window offset may be modified for both the four-step RACH procedure and the two-step RACH procedure. In one aspect, in a unified design, a common timing advance (TA) based on a reference point in a satellite beam or cell may be used as the RAR window offset for all UEs. In one aspect, a common TA may be used as the RAR window offset for all UEs without location information. The UE may transmit Msg1 in the four-step RACH procedure or transmit MsgA in the two-step RACH procedure with the common TA. In one aspect, a complete TA that accounts for the UE-specific propagation delay may be set as the RAR window offset for UEs with location information. The UE may transmit Msg1 or MsgA with the complete TA.

[0077] In one aspect, for a two-step RACH procedure, the base station may blindly retransmit MsgB within the RAR window, which is nominally 40 ms, 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. MsgB-RNTI may be set equal to (1+s_id+14xt_id+14x80xf_id+14x80x8xul_carrier_id+14x80x8x2). In one aspect, the number of blind retransmissions and / or the retransmission pattern may depend on the PRACH reception state or the PUSCH reception state. In one aspect, the retransmission pattern may be preconfigured.

[0078] In one aspect, the base station may extend the values ​​of K1 and K2, which determine the delay between uplink and downlink transmissions, to align a Time Domain Duplex (TDD) uplink-downlink configuration due to the long propagation delay associated with the NTN. For example, K1 may be the time gap in 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 be nominally 15 slots. K2 may be the time gap in slots between the 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 be nominally 32 slots. The PUSCH and PUCCH transmission times scheduled by the DCI may be indicated by K1 and K2.

[0079] FIG. 10 shows the timing relationship in the NTN between the base station and the UE using timing advance adjustment for the UE based on the round trip propagation delay between the base station and the UE. In the NTN, an additional offset K offsetmay be added to the PUSCH or PUCCH transmission. For example, in FIG. 10, 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 may 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 offset may be used to adjust the PUSCH. However, an additional time offset K offset Depending on, the resulting slot for PUSCH or PUCCH transmission may coincide with the downlink slot. In one aspect, to align the delayed PUSCH or PUCCH transmission with the uplink slot, the maximum value of K1 may be extended to 31 slots and the maximum value of K2 may be extended to 64 slots.

[0080] In one aspect, the base station may broadcast a new RAR window value to the UE to expand the RAR window size based on whether the satellite is LEO, GEO, or other. In one aspect, the base station may broadcast the new RAR window value using System Information Block Type 1 (SIB1). In one aspect, a new SIB1 information element may be used or a current information element such as "RACHConfigCommon IE" may be used by adding a new element for NTN.

[0081] 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 used. In one aspect, the RAR window value may be set based on the current load and network capacity to ensure that other parameters are also appropriately extended. This may include an estimation of how long the delay in response from the network may be for MsgB in a two-step RACH procedure, or for Msg2 / 4 in a four-step RACH procedure, and what behavior the UE may take during the intermediate sleep duration.

[0082] In one aspect, the base station may multicast the new RAR window size value using a page message. Since page messages are infrequent compared to SIB1 used for broadcast messages, the network may not be able to respond to significant spikes in network access traffic. The page message size may need to be increased to include additional information for the new RAR window size value. However, network efficiency may be achieved because only UEs targeted by the page message utilize the additional information elements and not all UEs in the NTN change their RACH behavior. In one aspect, the page message may be restricted to only downlink traffic so that UEs that may perform a RACH procedure due to uplink traffic cannot utilize this enhancement. In one aspect, any downlink page targeted to a UE may carry the new window size value instead of using multicast for all UEs. In one aspect, the page message may be restricted to UEs that meet a specific International Mobile Subscription Identity (IMSI).

[0083] FIG. 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 an RAR message from the base station over an extended RAR window to perform a RACH procedure in accordance with certain aspects of the disclosure.

[0084] In operation 1101, a UE transmits a PRACH preamble to a base station of an NTN in a frame of a frame structure including multiple frames to request access to the NTN.

[0085] In operation 1103, the UE receives a random access response RAR message from the base station during a RAR window, the RAR window spanning multiple frames of the frame structure.

[0086] In 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.

[0087] FIG. 12 is a flow diagram illustrating an example of a method for a base station of an NTN to receive a PRACH preamble from a UE, determine an RNTI, and transmit an RAR to the UE based on the RNTI over an extended RAR window, in accordance with some aspects of the present disclosure.

[0088] In operation 1201, the base station receives a PRACH preamble from a UE during a frame of a frame structure that includes several frames for requesting access to an NTN.

[0089] In operation 1203, the base station determines the RNTI from a time-frequency resource of the frame used to carry the PRACH preamble.

[0090] In operation 1205, the base station transmits a DCI that schedules an RAR message during an RAR window that spans multiple frames. The DCI includes an indication to enable 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.

[0091] 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, by a network computer, a network server, a tablet computer, a smartphone, a laptop computer, a desktop computer, other consumer electronic devices, or other data processing systems. In particular, the described operations 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 memory and execute the instructions to perform the described operations. These memories represent examples of machine-readable non-transitory storage media that can store or include computer program instructions that, when executed, cause the data processing system to perform one or more of the methods described herein. The processor may be a processor of a local device, such as a smartphone, a processor of a remote server, or a distributed processing system of multiple processors of local devices and remote servers, whose respective memories include various portions of the instructions necessary to perform the described operations.

[0092] While certain illustrative examples have been described and illustrated in the accompanying drawings, it is to be understood that these are merely illustrative of the broad invention of the disclosure and are not limiting thereto, and that since various other modifications may occur to those skilled in the art, the disclosure is not limited to the specific constructions and arrangements shown and described. Accordingly, the description is to be regarded in an illustrative rather than restrictive sense.

Claims

1. 1. A method by a wireless user equipment (UE) in a non-terrestrial based communications network, comprising: transmitting, by the UE, a Physical Random Access Channel (PRACH) preamble in a frame of a frame structure including a plurality of frames to a base station of the non-terrestrial communication network to request access to the non-terrestrial communication network; receiving, by the UE, a random access response (RAR) message from the base station during a random access response (RAR) window, the RAR window spanning two frames of the frame structure; determining, by the UE, whether the RAR message received from the base station is intended for the UE based on an indication in a downlink control information (DCI) that schedules the RAR message; determining that the RAR message is intended for the UE; determining a Radio Network Temporary Identifier (RNTI) based on a time-frequency resource of the frame used to transmit the PRACH preamble; Detecting that a portion of a cyclic redundancy check (CRC) of the DCI of the RAR message, identified by a frame number of the frame used by the UE to transmit the PRACH preamble, is scrambled by the RNTI, where the portion of the CRC of the DCI that is scrambled by the RNTI is identified by an odd or even frame of a frame number of the frame used by the UE to transmit the PRACH preamble; determining whether receiving, by the UE, a time gap value from the base station; receiving, by the UE, a downlink transmission from the base station; transmitting, by the UE from the base station, an acknowledgment of the downlink transmission, the time gap value indicating a delay between receiving the downlink transmission and transmitting the acknowledgment of the downlink transmission; A method comprising:

2. determining that the RAR message is intended for the UE; determining, by the UE, a Radio Network Temporary Identifier (RNTI) based on a time-frequency resource of the frame used to transmit the PRACH preamble; Detecting, by the UE, that a Cyclic Redundancy Check (CRC) of the DCI of the RAR message is scrambled by the RNTI; determining, by the UE, that a field in the DCI identifying a frame number of a triggering PRACH associated with the RAR matches the frame used by the UE to transmit the PRACH preamble; The method of claim 1 , comprising:

3. The method of claim 2 , further comprising identifying the frame number of the triggering PRACH as an even frame or an odd frame.

4. determining that the RAR message is intended for the UE; determining, by the UE, a Radio Network Temporary Identifier (RNTI) based on a time-frequency resource and a frame number of the frame used to transmit the PRACH preamble; determining, by the UE, that a cyclic redundancy check (CRC) of the DCI of the RAR message is scrambled by the RNTI; The method of claim 1 , comprising:

5. 5. The method of claim 4, wherein the RNTI is determined based on the time-frequency resource of the frame and the frame number used to transmit the PRACH preamble identified as an odd frame or an even frame.

6. transmitting, by the UE, the PRACH preamble; The method of claim 1 , comprising repeatedly transmitting the PRACH preamble using the same time-frequency resources of multiple frames of the frame structure.

7. Repeatedly transmitting the PRACH preamble using the same time-frequency resource of a plurality of frames. transmitting the PRACH at increasing power over the plurality of frames; Incrementing a preamble power ramp counter by the number of repeated PRACH preamble transmissions; The method of claim 6, comprising:

8. The method of claim 1 , wherein the time gap value is adaptable to align acknowledgments of the downlink transmissions with uplink slots of the frame structure.

9. 2. The method of claim 1, wherein the time gap value indicates a delay between receiving the downlink transmission and transmitting an acknowledgment of the downlink transmission as a number of slots of the frame structure, the delay comprising a maximum value of 31 slots.

10. 2. The method of claim 1, further comprising: determining, by the UE, a Timing Advance (TA) value, the TA value being adaptable to match a frame structure between the UE and the base station to account for a propagation delay between the UE and the base station; and receiving, by the UE, the TA value.

11. The method of claim 10, wherein the TA value is determined based on location information of the UE or based on an assumption that the UE is at a common reference position in a coverage area of ​​the base station.

12. The method of claim 10, wherein receiving the RAR message includes offsetting a start of an RAR window from an end of the PRACH preamble transmitted from the UE by the TA value, and transmitting the PRACH preamble includes transmitting the PRACH preamble using the TA to account for propagation delay between the UE and the base station.

13. 1. A baseband processor for wireless user equipment (UE), comprising: transmitting a Physical Random Access Channel (PRACH) preamble to a base station of the non-terrestrial communication network in a frame of a frame structure including a plurality of frames requesting access to the non-terrestrial communication network; receiving a RAR message from the base station during a random access response (RAR) window, the RAR window spanning two frames of the frame structure; determining whether the RAR message received from the base station is intended for the UE based on an indication in a Downlink Control Information (DCI) of the RAR message; determining whether the RAR message is intended for the UE; determining a Radio Network Temporary Identifier (RNTI) based on a time-frequency resource of the frame used to transmit the PRACH preamble; Detecting that a portion of a cyclic redundancy check (CRC) of the DCI of the RAR message, identified by a frame number of the frame used by the UE to transmit the PRACH preamble, is scrambled by the RNTI; determining whether receiving, by the UE, a time gap value from the base station; receiving, by the UE, a downlink transmission from the base station; transmitting, by the UE from the base station, an acknowledgment of the downlink transmission, the time gap value indicating a delay between receiving the downlink transmission and transmitting the acknowledgment of the downlink transmission. A baseband processor of a wireless user equipment (UE) configured to perform operations including:

14. the time gap value is adaptable to align acknowledgments of the downlink transmissions with uplink slots of the frame structure.

14. The baseband processor of claim 13.

15. 15. The baseband processor of claim 14, wherein the time gap value indicates a delay between receiving the downlink transmission and transmitting an acknowledgment of the downlink transmission as a number of slots of the frame structure, the delay comprising a maximum value of 31 slots.

16. Determining a Timing Advance (TA) value by the UE 14. The baseband processor of claim 13, further comprising operations for: determining whether the TA value is adaptive to match a frame structure between the UE and the base station to account for a propagation delay between the UE and the base station.

17. 17. The baseband processor of claim 16, wherein receiving the RAR message includes offsetting a start of an RAR window from an end of the PRACH preamble transmitted from the UE by the TA value, and transmitting the PRACH preamble includes transmitting a PRACH preamble using the TA to account for propagation delay between the UE and the base station.

18. 4. The method of claim 3, wherein the operation for transmitting the PRACH preamble further comprises: The baseband processor of claim 13 , further comprising operations for repeatedly transmitting the PRACH preamble using identical time-frequency resources of multiple frames of the frame structure.

19. The operation for repeatedly transmitting the PRACH preamble using the same time-frequency resource of a plurality of frames comprises: Transmitting the PRACH at increasing power over the plurality of frames; Incrementing the preamble power rise counter by the number of repeated PRACH preamble transmissions; The baseband processor of claim 18 comprising operations for:

20. 14. The baseband processor of claim 13, wherein the portion of the CRC of the DCI scrambled by the RNTI is identified by an odd or even frame of the frame number of the frames used by the UE to transmit the PRACH preamble.

21. 1. A user equipment (UE) device, the user equipment device comprising: At least one antenna; at least one radio configured to communicate with a base station of a non-terrestrial based communications network using the at least one antenna; at least one processor coupled to the at least one radio, the at least one processor comprising: transmitting a Physical Random Access Channel (PRACH) preamble to a base station of the non-terrestrial communication network in a frame of a frame structure including a plurality of frames requesting access to the non-terrestrial communication network; receiving a random access response (RAR) message from the base station during a RAR window, the RAR window spanning two frames of the frame structure; determining whether the RAR message received from the base station is intended for the UE based on an indication in a Downlink Control Information (DCI) of the RAR message; determining that the RAR message is intended for the UE; determining a Radio Network Temporary Identifier (RNTI) based on a time-frequency resource of the frame used to transmit the PRACH preamble; Detecting that a portion of a cyclic redundancy check (CRC) of the DCI of the RAR message, identified by a frame number of the frame used by the UE to transmit the PRACH preamble, is scrambled by the RNTI, where the portion of the CRC of the DCI that is scrambled by the RNTI is identified by an odd or even frame of a frame number of the frame used by the UE to transmit the PRACH preamble; determining whether receiving, by the UE, a time gap value from the base station; receiving, by the UE, a downlink transmission from the base station; transmitting, by the UE from the base station, an acknowledgment of the downlink transmission, the time gap value indicating a delay between receiving the downlink transmission and transmitting the acknowledgment of the downlink transmission; and A user equipment (UE) device comprising:

22. 22. The UE device of claim 21, wherein the time gap value is adaptable to align acknowledgements of the downlink transmissions with uplink slots of the frame structure.

23. 22. The UE device of claim 21, wherein the time gap value indicates a delay between receiving the downlink transmission and transmitting an acknowledgment of the downlink transmission as a number of slots of the frame structure.

24. The UE device of claim 21 , wherein the delay comprises a maximum value of 31 slots.

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