Random access procedure for New Radio (NR) networks

Abstract

A method for wireless communication by a user equipment (UE) calculates a propagation delay for sending a message from the UE to a network node such as a base station via non-terrestrial communication. The method sends a random access preamble to the base station while accounting for the calculated propagation delay. The method starts a random access response (RAR) window at a first physical downlink control channel (PDCCH) opportunity after twice the calculated propagation delay from sending the random access preamble. The method receives a RAR message from the base station during the random access response (RAR) window. The RAR message includes an uplink grant for indicating an uplink shared channel resource. Further, the method sends an uplink message to arrive during the uplink shared channel resource while accounting for the calculated propagation delay.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of U.S. Patent Application No. 17 / 165,272, filed on February 2, 2021, entitled “RANDOMACCESS PROCEDURES FOR NEW RADIO (NR) NETWORKS,” which claims the benefit of U.S. Provisional Patent Application No. 62 / 971,821, filed on February 7, 2020, entitled “RANDOMACCESS PROCEDURES FOR NEW RADIO (NR) NON-TERRESTRIAL NETWORKS,” the disclosures of both of which are expressly incorporated herein by reference in their entirety. Technical Field

[0003] The present disclosure relates generally to wireless communications, and more particularly to random access procedures for wireless networks, such as non-terrestrial networks (NTNs). Background Art

[0004] Wireless communication networks are widely deployed to provide various types of communication content, such as voice, video, packet data, messaging, broadcasting, etc. These systems may be able to support communication with multiple users by sharing available system resources (e.g., time, frequency, and power). Examples of such multiple access systems include fourth generation (4G) systems such as long term evolution (LTE) systems, improved LTE (LTE-A) systems, or LTE-A Pro systems, and fifth generation (5G) systems that may be referred to as new radio (NR) systems. These systems may employ techniques such as code division multiple access (CDMA), time division multiple access (TDMA), frequency division multiple access (FDMA), orthogonal frequency division multiple access (OFDMA), or discrete Fourier transform spread OFDM (DFT-S-OFDM). A wireless multiple access communication system may include a number of base stations or network access nodes, each of which simultaneously supports communication for multiple communication devices, which may be referred to as user equipment (UE).

[0005] Some examples of wireless communication systems may be non-terrestrial networks, which may utilize satellites and high-altitude platforms (e.g., drones) as relays for communicating with ground equipment. Alternatively, satellites and high-altitude platforms may operate themselves as base stations. In non-terrestrial networks, the propagation delay of wireless transmissions may be larger than that of terrestrial wireless network transmissions. In some cases, the techniques for implementing random access of wireless communications in terrestrial wireless networks may need to be improved for use in non-terrestrial networks. Therefore, future solutions are expected. Summary of the invention

[0006] In one aspect of the present disclosure, a method for wireless communication by a user equipment (UE) includes: receiving information for estimating a propagation delay between the UE and a network node accessed via non-terrestrial communication. The method also includes: sending a physical random access channel (PRACH) preamble to the network node at a user-specific timing advance period before a random access channel (RACH) opportunity at the UE, the user-specific timing advance period corresponding to the propagation delay.

[0007] Another aspect of the present disclosure is directed to an apparatus for wireless communication by a UE. The apparatus includes: a unit for receiving information for estimating a propagation delay between the UE and a network node accessed via non-terrestrial communication. The apparatus also includes: a unit for sending a physical random access channel (PRACH) preamble to the network node at a user-specific timing advance period before a random access channel (RACH) opportunity at the UE, the user-specific timing advance period corresponding to the propagation delay.

[0008] In another aspect of the present disclosure, a non-transitory computer-readable medium having program code recorded thereon is disclosed. The program code is executed by a processor and includes program code for receiving information for estimating a propagation delay between a UE and a network node accessed via non-terrestrial communication. The program code also includes code for sending a physical random access channel (PRACH) preamble to a network node at a user-specific timing advance period before a random access channel (RACH) opportunity at the UE, the user-specific timing advance period corresponding to the propagation delay.

[0009] Another aspect of the present disclosure is directed to an apparatus for wireless communication for a UE. The apparatus includes a memory and one or more processors coupled to the memory. The memory and the one or more processors are configured to receive information for estimating a propagation delay between the UE and a network node accessed via non-terrestrial communication. The memory and the one or more processors are configured to send a physical random access channel (PRACH) preamble to the network node during a user-specific timing advance period before a random access channel (RACH) opportunity at the UE, the user-specific timing advance period corresponding to the propagation delay.

[0010] In one aspect of the present disclosure, a method for wireless communication by a network node in a non-terrestrial network includes sending information to a user equipment (UE) for estimating a propagation delay between the UE and the network node. The method also includes receiving a physical random access channel (PRACH) preamble from the UE at a user-specific timing advance period after the UE sends the PRACH preamble, the user-specific timing advance period corresponding to the propagation delay.

[0011] Another aspect of the present disclosure is directed to an apparatus of a network node in a non-terrestrial network. The apparatus includes means for sending information for estimating a propagation delay between a user equipment (UE) and the network node. The apparatus also includes means for receiving a physical random access channel (PRACH) preamble from the UE at a user-specific timing advance period after the UE sends the PRACH preamble, the user-specific timing advance period corresponding to the propagation delay.

[0012] In another aspect of the present disclosure, a non-transitory computer-readable medium has program code recorded thereon for a network node in a non-terrestrial network. The program code is processed by a processor and includes program code for sending information for estimating a propagation delay between a UE and the network node to a user equipment (UE). The program code also includes program code for receiving a physical random access channel (PRACH) preamble from the UE at a user-specific timing advance period after the UE sends the PRACH preamble, the user-specific timing advance period corresponding to the propagation delay.

[0013] Another aspect of the present disclosure is directed to an apparatus of a network node in a non-terrestrial network. The apparatus has a memory and one or more processors coupled to the memory. The memory and the one or more processors may be configured to send information for estimating a propagation delay between a UE and a network node to a user equipment (UE). The memory and the one or more processors may also be configured to receive a PRACH preamble from a UE during a user-specific timing advance period after the UE sends a PRACH preamble, the user-specific timing advance period corresponding to the propagation delay.

[0014] The described techniques relate to improved methods, systems, devices, and apparatuses that support random access procedures for non-terrestrial networks. In general, the described techniques provide for a wireless communication system that may be a non-terrestrial network, which may include a base station (e.g., a gateway), a user equipment (UE), and a satellite that wirelessly communicates with the base station and the UE, among other components. In some cases, the base station may be integrated or hosted on a satellite.

[0015] Some examples of the methods, apparatus, and non-transitory computer-readable media described herein may also include operations, features, units, or instructions for: generating a configuration for a UE including a reference signal (RS) periodicity, an indication of a symbol of a time slot, and an indication of frequency resources for upstream transmission; and sending the configuration to the UE during a connection process with the UE. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1An example of a wireless communication system supporting a random access procedure for a non-terrestrial network in accordance with one or more aspects of the present disclosure is shown.

[0017] Figure 2 An example of a wireless communication system supporting a random access procedure for a non-terrestrial network in accordance with one or more aspects of the present disclosure is shown.

[0018] Figure 3 An example of a non-terrestrial network supporting a random access procedure for the non-terrestrial network in accordance with one or more aspects of the present disclosure is shown.

[0019] Figure 4 An example of a non-terrestrial network supporting a random access procedure for the non-terrestrial network in accordance with one or more aspects of the present disclosure is shown.

[0020] Figure 5 An example of a non-terrestrial network including propagation delays in accordance with one or more aspects of the present disclosure is shown.

[0021] Figure 6 is a timing diagram illustrating an example random access procedure targeting the same random access channel (RACH) opportunity according to one or more aspects of the present disclosure.

[0022] Figure 7 is a timing diagram illustrating an exemplary random access procedure with periodic pre-allocation of physical uplink shared channel (PUSCH) resources according to one or more aspects of the present disclosure.

[0023] Figure 8 is a timing diagram illustrating an exemplary random access procedure with a physical uplink shared channel (PUSCH) resource based on propagation delay time according to one or more aspects of the present disclosure.

[0024] Fig. 9 is a timing diagram illustrating an example random access procedure with user equipment (UE)-specific random access channel (RACH) opportunities and a common physical uplink shared channel (PUSCH) scheduling window according to one or more aspects of the present disclosure.

[0025] Fig.10 is a timing diagram illustrating an example random access procedure with UE-specific random access channel (RACH) opportunities and UE-specific physical uplink shared channel (PUSCH) resources according to one or more aspects of the present disclosure.

[0026] Fig.11is a timing diagram illustrating an example random access procedure with UE-specific random access channel (RACH) opportunities and a random access response (RAR) window based on the UE-specific RACH opportunities according to one or more aspects of the present disclosure.

[0027] Fig.12 is a timing diagram illustrating an example random access procedure targeting the same random access channel (RACH) opportunity and common physical uplink shared channel (PUSCH) scheduling window according to one or more aspects of the present disclosure.

[0028] Fig.13 is a flow chart illustrating an exemplary process, for example, performed by a user device, according to various aspects of the present disclosure.

[0029] Fig.14 is a flow chart illustrating an exemplary process, for example, performed by a network device, according to various aspects of the present disclosure. DETAILED DESCRIPTION

[0030] A wireless communication system may be a non-terrestrial network including a base station, which may utilize a satellite (e.g., a non-geosynchronous satellite) to relay communications to one or more user equipments (UEs). In other scenarios, a satellite may operate as a base station. Due to the mobility of the satellite, communications may experience timing errors (e.g., changes in propagation delays). For non-terrestrial networks, it may be necessary to improve some techniques for random access associated with wireless transmissions in terrestrial wireless networks. According to one or more of the described techniques, a base station and a UE that wirelessly communicate with a satellite may support a random access procedure for addressing propagation delays caused by the mobility of the UE and the satellite.

[0031] Various aspects of the present disclosure provide techniques for aligning random access channel (RACH) timings between a UE and a network node (e.g., an eNB / gNB (also referred to as a base station)). In some aspects of the present disclosure, the UE may estimate one-way propagation delays from the UE to a satellite and from a satellite to a ground base station. In other aspects, random access response (RAR) window timing is set based on downlink (DL) propagation delays. One or more examples address uplink (UL) grant processing in the RAR (e.g., message two (Msg2) of a random access procedure), where in one example the RAR includes an uplink grant. In this example, message three (Msg3) of the random access procedure may be sent based on the uplink grant of the RAR.

[0032] Various options are available for the UE to estimate the total one-way propagation delay. In one option, the UE can estimate the total one-way propagation delay by using a timestamp provided in a synchronization signal block (SSB), a physical broadcast channel (PBCH), or a system information broadcast (SIB) message. For example, the timestamp may be provided in a system information block one (SIB1) message and / or an NTN-specific SIB message. The UE can estimate the propagation delay based on the timestamp and the reception time. In another option, the UE can estimate the total one-way propagation delay by using a universal time for subframe number (SFN) timing. For example, UTC (coordinated universal time) starting at a specific time can be assigned to system frame number zero (SFN0). The UE can estimate the propagation delay based on the boundary of SFN 0. An indication of whether the cell is using coordinated universal time for SFN timing may be provided in a SIB message. In some aspects, the indication may be provided if the base station does not follow a specific time reference.

[0033] To enable preamble transmission, in accordance with one or more aspects of the present disclosure, each UE may estimate the SFN of the base station based on satellite ephemeris data and the respective positions of each UE. Each UE may then calculate the one-way propagation delay time (D) between the UE and the base station. Each UE may send a physical random access channel (PRACH) preamble "D" time units before the start of the RACH opportunity on the gNB side. Thus, each UE has a UE-specific timing advance. In other words, each UE may pre-compensate for delay when sending its preamble. In one example, if the UE's RACH opportunity (RO) is D time units after the gNB's RO, the preamble is sent 2*D time units earlier than the UE's RO.

[0034] In one or more examples, after receiving the preamble, the base station may start a random access response (RAR) window during which the base station may send a RAR to each UE. According to one or more aspects of the present disclosure, each UE may start a random access response (RAR) reception window at the first physical downlink control channel (PDCCH) opportunity after two UE-specific timing advances (e.g., 2*D) from the end of the random access preamble transmission.

[0035] One or more aspects of the present disclosure are directed to scheduling a physical uplink shared channel (PUSCH). In some aspects, a PUSCH scheduling window for a base station may start at a period T after the start of a base station RAR window. In one example, period T is the gap between the RAR window and the earliest PUSCH position for the base station.

[0036] According to one or more aspects of the present disclosure, the period T may be calculated as:

[0037] T = 2 * Dmax + RAR window + TA (Timing Advance),

[0038] where Dmax is the maximum one-way propagation delay time from any UE to the base station in a given cell. In other words, in one example, Dmax can correspond to the propagation delay for the UE that is farthest from the base station. The timing advance value TA can be assumed with respect to the downlink (DL) reference timing. The RAR window can be the duration of the window for receiving and processing the RAR.

[0039] According to one example, the earliest time at which a UE can send Msg3 in the PUSCH can be D time units before the start of the PUSCH scheduling window. In other aspects of the present disclosure, the UE can be scheduled with random resources, and the UE can select the best resources, as described in more detail below.

[0040] According to one or more aspects of the present disclosure, periodically pre-allocated uplink (UL) (e.g., PUSCH) resources can be used to send Msg3. In one example, the periodic allocation can replace the resources indicated in the RAR message (Msg2). The starting point of the pre-allocated periodic PUSCH resources can be the time (Dmin + TA) from the end of the RAR message or the RAR window, delaying the minimum propagation delay (Dmin). The parameter Dmin can be the minimum one-way propagation delay time from the UE to the base station in a given cell, in other words, the propagation delay from the nearest UE to the base station. In this aspect of the present disclosure, the UE can select the first available resource.

[0041] In still other aspects, the UE can indicate the amount of its delay in its preamble. That is, the preamble can inform the network about UE-specific delay. According to these aspects, the PUSCH can be scheduled according to delay groups. For example, UEs can be grouped according to their respective delays. For example, the preambles can be divided into X groups to account for X one-way propagation delay times (D1, D2... DX), where DX = Dmax / X. The starting point of the PUSCH scheduling window can be calculated based on the group ID corresponding to the preamble received by the base station. In other words, the preamble can inform the network about the delay. The network can schedule the PUSCH according to the delay groups. In these aspects, UEs having a one-way propagation delay D (such that D2 < D <= D1) can use the preamble group corresponding to D1.

[0042] According to one or more examples of the present disclosure, all UEs may have the same timing advance, rather than a UE-specific timing advance. For example, a delay Dmax may be assigned to each UE. In these aspects, the base station may not receive preambles from all UEs at the same time. Each UE may transmit at its own RACH opportunity (RO). Therefore, the base station may set a preamble reception window to receive preambles from all possible UEs. This option may be used for UEs with or without GNSS capabilities.

[0043] The techniques mentioned above and described in more detail below implement a random access procedure within a non-terrestrial network. Although aspects of the present disclosure are initially described in the context of a non-terrestrial network, it should be noted that aspects of the present disclosure are applicable to terrestrial networks in addition to non-terrestrial networks where propagation delays may be an issue. Aspects of the present disclosure are illustrated and described with reference to process flows. Aspects of the present disclosure are further illustrated and described with reference to device diagrams, system diagrams, and flow charts related to random access procedures for networks (such as non-terrestrial networks).

[0044] Figure 1 An example of a wireless communication system 100 supporting a random access procedure for a non-terrestrial network according to one or more aspects of the present disclosure is shown. The wireless communication system 100 includes a base station 105, a UE 115, and a core network 130. In some examples, the wireless communication system 100 may be a long term evolution (LTE) network, an improved LTE (LTE-A) network, an LTE-A Pro network, or a new radio (NR) network. In some cases, the wireless communication system 100 may support enhanced broadband communications, ultra-reliable (e.g., mission-critical) communications, low-latency communications, or communications with low-cost and low-complexity devices.

[0045] The base station 105 may communicate wirelessly with the UE 115 via one or more base station antennas. The described base station 105 may include or may be referred to by those skilled in the art as a base station transceiver, a wireless base station, an access point, a wireless transceiver, a NodeB, an evolved NodeB (eNodeB, eNB), a next generation NodeB or a Gigabit NodeB (either of which may be referred to as a gNB), a Home NodeB, a Home eNodeB, or some other suitable terminology. The wireless communication system 100 may include different types of base stations 105 (e.g., macro cell base stations or small cell base stations). The UE 115 described herein may be able to communicate with various types of base stations 105 and network devices (including macro eNBs, small cell eNBs, gNBs, relay base stations, etc.).

[0046] Each base station 105 may be associated with a particular geographic coverage area 110 in which it supports communications with various UEs 115. Each base station 105 may provide communication coverage for a respective geographic coverage area 110 via a communication link 125, and the communication link 125 between the base station 105 and the UE 115 may utilize one or more carriers. The communication link 125 shown in the wireless communication system 100 may include an upstream transmission from the UE 115 to the base station 105, or a downstream transmission from the base station 105 to the UE 115. Downstream transmissions may also be referred to as downlink or forward link transmissions, while upstream transmissions may also be referred to as uplink or reverse link transmissions.

[0047] The geographic coverage area 110 for the base station 105 can be divided into sectors, each sector constituting a portion of the geographic coverage area 110, and each sector can be associated with a cell. For example, each base station 105 can provide communication coverage for a macro cell, a small cell, a hotspot, or other type of cell, or various combinations thereof. In some examples, the base station 105 can be mobile and thus provide communication coverage for a mobile geographic coverage area 110. In some examples, different geographic coverage areas 110 associated with different technologies can overlap, and overlapping geographic coverage areas 110 associated with different technologies can be supported by the same base station 105 or different base stations 105. The wireless communication system 100 may include, for example, a heterogeneous LTE / LTE-A / LTE-A Pro or NR network in which different types of base stations 105 provide coverage for various geographic coverage areas 110.

[0048] The term "cell" refers to a logical communication entity used to communicate with a base station 105 (e.g., via a carrier) or a satellite beam, and may be associated with an identifier (e.g., a physical cell identifier (PCID), a virtual cell identifier (VCID)) used to distinguish between neighboring cells operating via the same or different carriers. In some examples, a carrier may support multiple cells, and different cells may be configured according to different protocol types (e.g., machine type communication (MTC), narrowband Internet of Things (NB-IoT), enhanced mobile broadband (eMBB), or other) that may provide access to different types of devices. In some cases, the term "cell" may refer to a portion (e.g., a sector) of a geographic coverage area 110 over which the logical entity operates.

[0049] UE 115 can be dispersed throughout the wireless communication system 100, and each UE 115 can be stationary or mobile. UE 115 can also be referred to as a mobile device, a wireless device, a remote device, a handheld device or a user device, or some other suitable term, where "device" can also be referred to as a unit, a station, a terminal or a client. UE 115 can also be a personal electronic device, such as a cellular phone, a personal digital assistant (PDA), a tablet computer, a laptop computer or a personal computer. In some examples, UE 115 can also refer to a wireless local loop (WLL) station, an Internet of Things (IoT) device, an Internet of Everything (IoE) device or an MTC device, etc., which can be implemented in various items (such as electrical appliances, vehicles, meters, etc.).

[0050] Some UEs 115, such as MTC or IoT devices, may be low-cost or low-complexity devices and may provide for automated communication between machines, for example, via machine-to-machine (M2M) communication. M2M communication or MTC may refer to data communication technology that allows devices to communicate with each other or with a base station 105 without human intervention. In some examples, M2M communication or MTC may include communication from devices that integrate sensors or meters to measure or capture information and relay the information to a central server or application, which may utilize the information or present the information to a person interacting with the program or application. Some UEs 115 may be designed to collect information or implement automated behavior of machines. Examples of applications for MTC devices include smart metering, inventory monitoring, water level monitoring, equipment monitoring, healthcare monitoring, wildlife monitoring, weather and geological event monitoring, fleet management and tracking, remote security sensing, physical access control, and transaction-based commercial billing.

[0051] Some UEs 115 may be configured to employ a reduced power consumption mode of operation, such as half-duplex communication (e.g., a mode that supports one-way communication via transmission or reception but not simultaneous transmission and reception). In some examples, half-duplex communication may be performed at a reduced peak rate. Other power saving techniques for UE 115 include entering a power saving "deep sleep" mode when not engaged in active communications, or operating over a limited bandwidth (e.g., based on narrowband communications). In some cases, UE 115 may be designed to support critical functions (e.g., mission critical functions), and the wireless communication system 100 may be configured to provide ultra-reliable communications for these functions.

[0052] In some cases, UE 115 may also be able to communicate directly with other UE 115 (e.g., using peer-to-peer (P2P) or device-to-device (D2D) protocols). One or more UEs in a group of UEs 115 utilizing D2D communication may be within the geographic coverage area 110 of the base station 105. Other UEs 115 in such a group may be outside the geographic coverage area 110 of the base station 105 or otherwise unable to receive transmissions from the base station 105. In some cases, groups of UEs 115 communicating via D2D communication may utilize a one-to-many (1:M) system in which each UE 115 transmits to each other UE 115 in the group. In some cases, the base station 105 facilitates scheduling resources for D2D communication. In other cases, D2D communication is performed between UEs 115 without involving the base station 105.

[0053] The base stations 105 may communicate with the core network 130 and with each other. For example, the base stations 105 may interface with the core network 130 via a backhaul link 132 (e.g., via an S1, N2, N3, or other interface). The base stations 105 may communicate with each other directly (e.g., directly between the base stations 105) or indirectly (e.g., via the core network 130) via a backhaul link 134 (e.g., via an X2, Xn, or other interface).

[0054] The core network 130 may provide user authentication, access permission, tracking, Internet Protocol (IP) connectivity, and other access, routing, or mobility functions. The core network 130 may be an evolved packet core (EPC), which may include at least one mobility management entity (MME), at least one serving gateway (S-GW), and at least one packet data network (PDN) gateway (P-GW). The MME may manage non-access stratum (e.g., control plane) functions such as mobility, authentication, and bearer management for UEs 115 served by base stations 105 associated with the EPC. User IP packets may be transmitted via the S-GW, which itself may be connected to the P-GW. The P-GW may provide IP address allocation and other functions. The P-GW may be connected to network operator IP services. Operator IP services may include access to the Internet, an intranet, an IP multimedia subsystem (IMS), or a packet switched (PS) streaming service.

[0055] At least some of the network devices (such as base stations 105) may include subcomponents, such as access network entities, which may be examples of access node controllers (ANCs). Each access network entity may communicate with UE 115 through a number of other access network transport entities, which may be referred to as radio heads, smart radio heads, or transmit / receive points (TRPs). In some configurations, the various functions of each access network entity or base station 105 may be distributed across various network devices (e.g., radio heads and access network controllers) or merged into a single network device (e.g., base station 105).

[0056] The wireless communication system 100 can operate using one or more frequency bands, typically in the range of 300 MHz to 300 GHz. Typically, the region from 300 MHz to 3 GHz is referred to as the ultra-high frequency (UHF) region or decimeter band because the wavelengths range from about one decimeter to one meter in length. UHF waves may be blocked or redirected by buildings and environmental features. However, the waves can penetrate the structure enough for the macrocell to provide service to the UE 115 located indoors. Compared with the transmission of smaller frequencies and longer waves using the high frequency (HF) or very high frequency (VHF) portion of the spectrum below 300 MHz, the transmission of UHF waves may be associated with smaller antennas and shorter ranges (e.g., less than 100 km).

[0057] The wireless communication system 100 may also operate in the Super High Frequency (SHF) region using a frequency band from 3 GHz to 30 GHz (also referred to as the centimeter frequency band). The SHF region includes frequency bands such as the 5 GHz Industrial, Scientific and Medical (ISM) band, which may be used by devices that can tolerate interference from other users.

[0058] The wireless communication system 100 can also operate in the extremely high frequency (EHF) region of the spectrum (e.g., from 30 GHz to 300 GHz), also known as the millimeter frequency band. In some examples, the wireless communication system 100 can support millimeter wave (mmW) communications between the UE 115 and the base station 105, and the EHF antennas of the respective devices can be even smaller and more closely spaced than the UHF antennas. In some cases, this can facilitate the use of antenna arrays within the UE 115. However, the propagation of EHF transmissions may be subject to even greater atmospheric attenuation and shorter range than SHF or UHF transmissions. The technology disclosed herein can be adopted across transmissions using one or more different frequency regions, and the use of the frequency bands specified to span these frequency regions can vary from country to country or regulatory agency.

[0059] In some cases, the wireless communication system 100 may use both licensed and unlicensed radio frequency spectrum bands. For example, the wireless communication system 100 may adopt license assisted access (LAA), LTE unlicensed (LTE-U) radio access technology, or NR technology in an unlicensed band such as the 5GHz ISM band. When operating in an unlicensed radio frequency spectrum band, wireless devices such as base stations 105 and UE 115 may adopt a listen-before-talk (LBT) process to ensure that the frequency channel is idle before sending data. In some cases, operation in an unlicensed band may be based on a CA configuration combined with a CC operating in a licensed band (e.g., LAA). Operations in an unlicensed spectrum may include downstream transmissions, upstream transmissions, peer transmissions, or a combination of these. Duplexing in an unlicensed spectrum may be based on frequency division duplexing (FDD), time division duplexing (TDD), or a combination of both.

[0060] In some examples, the base station 105 or UE 115 may be equipped with multiple antennas, which may be used to employ techniques such as transmit diversity, receive diversity, multiple-input multiple-output (MIMO) communications, or beamforming. For example, the wireless communication system 100 may use a transmission scheme between a transmitting device (e.g., a base station 105) and a receiving device (e.g., a UE 115), wherein the transmitting device is equipped with multiple antennas and the receiving device is equipped with one or more antennas. MIMO communications may employ multipath signal propagation to increase spectral efficiency by transmitting or receiving multiple signals via different spatial layers, which may be referred to as spatial multiplexing. Multiple signals may be, for example, transmitted by a transmitting device via different antennas or different combinations of antennas. Similarly, multiple signals may be received by a receiving device via different antennas or different combinations of antennas. Each of the multiple signals may be referred to as a separate spatial stream, and may carry bits associated with the same data stream (e.g., the same codeword) or different data streams. Different spatial layers may be associated with different antenna ports for channel measurement and reporting. MIMO technology includes single-user MIMO (SU-MIMO) and multi-user MIMO (MU-MIMO). In SU-MIMO, multiple spatial layers are sent to the same receiving device, and in MU-MIMO, multiple spatial layers are sent to multiple devices.

[0061] Beamforming (which may also be referred to as spatial filtering, directional transmission, or directional reception) is a signal processing technique that may be used at a transmitting device or a receiving device (e.g., a base station 105 or a UE 115) to shape or steer an antenna beam (e.g., a transmit beam or a receive beam) along a spatial path between the transmitting device and the receiving device. Beamforming may be achieved by combining signals transmitted via antenna elements of an antenna array so that signals propagating in a particular direction relative to the antenna array experience constructive interference, while other signals experience destructive interference. Adjustments to signals transmitted via antenna elements may include the transmitting device or the receiving device applying certain amplitude and phase offsets to signals carried via each of the antenna elements associated with the device. Adjustments associated with each of the antenna elements may be defined by a set of beamforming weights associated with a particular orientation (e.g., relative to the antenna array of the transmitting device or the receiving device, or relative to some other orientation).

[0062] In one example, the base station 105 may use multiple antennas or antenna arrays to perform beamforming operations for directional communications with the UE 115. For example, some signals (e.g., synchronization signals, reference signals, beam selection signals, or other control signals) may be sent multiple times by the base station 105 in different directions, which may include signals sent according to different sets of beamforming weights associated with different transmission directions. Transmissions in different beam directions may be used to identify (e.g., by the base station 105 or a receiving device such as the UE 115) a beam direction for subsequent transmission and / or reception by the base station 105. Some signals (such as data signals associated with a particular receiving device) may be sent by the base station 105 in a single beam direction (e.g., a direction associated with a receiving device such as the UE 115). In some examples, the beam direction associated with transmissions along a single beam direction may be determined based at least in part on signals sent in different beam directions. For example, UE 115 may receive one or more signals transmitted by base station 105 in different directions, and UE 115 may report an indication of the signal it received having the highest signal quality or otherwise acceptable signal quality to base station 105. Although these techniques are described with reference to signals transmitted by base station 105 in one or more directions, UE 115 may employ similar techniques for transmitting signals multiple times in different directions (e.g., for identifying a beam direction for subsequent transmission or reception by UE 115), or for transmitting signals in a single direction (e.g., for transmitting data to a receiving device).

[0063] A receiving device (e.g., UE 115, which may be an example of a mmW receiving device) may attempt multiple receive beams when receiving various signals (such as synchronization signals, reference signals, beam selection signals, or other control signals) from base station 105. For example, the receiving device may attempt multiple receive directions by receiving via different antenna subarrays, by processing received signals according to different antenna subarrays, by receiving according to different receive beamforming weight sets applied to signals received at multiple antenna elements of an antenna array, or by processing received signals according to different receive beamforming weight sets applied to signals received at multiple antenna elements of an antenna array, any of which may be referred to as "listening" according to different receive beams or receive directions. In some examples, the receiving device may use a single receive beam to receive along a single beam direction (e.g., when receiving data signals). The single receive beam may be aligned in a beam direction determined at least in part based on listening according to different receive beam directions (e.g., a beam direction determined to have the highest signal strength, the highest signal-to-noise ratio, or otherwise acceptable signal quality based at least in part on listening according to multiple beam directions).

[0064] In some cases, the antennas of the base station 105 or UE 115 may be located within one or more antenna arrays, which may support MIMO operations, or transmit or receive beamforming. For example, one or more base station antennas or antenna arrays may be co-located at an antenna assembly (such as an antenna tower). In some cases, the antennas or antenna arrays associated with the base station 105 may be located in a variety of geographic locations. The base station 105 may have an antenna array having a number of rows and columns of antenna ports that the base station 105 may use to support beamforming for communications with the UE 115. Similarly, the UE 115 may have one or more antenna arrays that may support various MIMO or beamforming operations.

[0065] In some cases, the wireless communication system 100 may be a packet-based network operating according to a layered protocol stack. In the user plane, the communication at the bearer or packet data convergence protocol (PDCP) layer may be IP-based. The radio link control (RLC) layer may perform packet segmentation and reassembly in some cases to communicate through logical channels. The medium access control (MAC) layer may perform priority processing and multiplexing of logical channels to transport channels. The MAC layer may also use a hybrid automatic repeat request (HARQ) to provide retransmission at the MAC layer to improve link efficiency. In the control plane, the radio resource control (RRC) protocol layer may provide for the establishment, configuration and maintenance of an RRC connection between a UE 115 and a base station 105 or a core network 130 supporting a radio bearer for user plane data. At the physical (PHY) layer, a transport channel may be mapped to a physical channel.

[0066] In some cases, UE 115 and base station 105 can support retransmission of data to increase the possibility of successfully receiving data. HARQ feedback is a technique to increase the possibility of correctly receiving data through communication link 125. HARQ can include a combination of error detection (e.g., using cyclic redundancy check (CRC)), forward error correction (FEC) and retransmission (e.g., automatic repeat request (ARQ)). HARQ can improve the throughput at the MAC layer under poor radio conditions (e.g., signal-to-noise ratio conditions). In some cases, wireless devices can support same-slot HARQ feedback, where the device can provide HARQ feedback for data received in the previous symbol in the slot in a specific slot. In other cases, the device can provide HARQ feedback in subsequent slots or according to some other time interval.

[0067] A time interval in LTE or NR may be expressed in multiples of a basic time unit, which may refer to, for example, T s =1 / 30,720,000 second sampling period. The time intervals of the communication resources may be organized according to radio frames each having a duration of 10 milliseconds (ms), where the frame period may be denoted as T f =307,200T s. A radio frame may be identified by a system frame number (SFN) ranging from 0 to 1023. Each frame may include 10 subframes numbered from 0 to 9, each subframe may have a duration of 1 ms. A subframe may be further divided into 2 slots, each slot having a duration of 0.5 ms, and each slot may contain 6 or 7 modulation symbol periods (e.g., depending on the length of a cyclic prefix (CP) pre-appended to each symbol period). In addition to the cyclic prefix, each symbol period may contain 2048 sampling periods. In some cases, a subframe may be the minimum scheduling unit of the wireless communication system 100, and may be referred to as a transmission time interval (TTI). In other cases, the minimum scheduling unit of the wireless communication system 100 may be shorter than a subframe, or may be dynamically selected (e.g., in a burst of a shortened TTI (sTTI) or in a selected component carrier using an sTTI).

[0068] In some wireless communication systems, a time slot may also be divided into a plurality of mini-slots containing one or more symbols. In some cases, a symbol of a mini-slot or a mini-slot may be the minimum unit of scheduling. For example, each symbol may vary in duration depending on the subcarrier spacing or operating frequency band. Further, some wireless communication systems may implement time slot aggregation, in which a plurality of time slots or mini-slots are aggregated together and used for communication between UE 115 and base station 105.

[0069] The term "carrier" refers to a collection of radio frequency spectrum resources with a defined physical layer structure for supporting communications on the communication link 125. For example, a carrier of the communication link 125 may include a portion of a radio frequency spectrum band that operates according to a physical layer channel for a given radio access technology. Each physical layer channel may carry user data, control information, or other signaling. A carrier may be associated with a predefined frequency channel (e.g., an E-UTRA Absolute Radio Frequency Channel Number (EARFCN)) and may be located according to a channel grid for discovery by a UE 115. A carrier may be downstream or upstream (e.g., in FDD mode), or configured to carry downstream and upstream communications (e.g., in TDD mode). In some examples, a signal waveform sent on a carrier may be composed of multiple subcarriers (e.g., using a multi-carrier modulation (MCM) technique such as OFDM or DFT-s-OFDM).

[0070] The organization structure of the carrier may be different for different radio access technologies (e.g., LTE, LTE-A, LTE-A Pro, NR, etc.). For example, communication through the carrier may be organized according to TTIs or time slots, each of which may include user data and control information or signaling to support decoding of the user data. The carrier may also include dedicated acquisition signaling (e.g., synchronization signals or system information, etc.) and control signaling to coordinate operations for the carrier. In some examples (e.g., in a carrier aggregation configuration), the carrier may also have acquisition signaling or control signaling to coordinate operations for other carriers.

[0071] The physical channels may be multiplexed on a carrier according to various techniques. The physical control channel and the physical data channel may be multiplexed on a downstream carrier, for example, using a time division multiplexing (TDM) technique, a frequency division multiplexing (FDM) technique, or a hybrid TDM-FDM technique. In some examples, the control information sent in the physical control channel may be distributed in a cascaded manner between different control regions (e.g., between a common control region or common search space and one or more UE-specific control regions or UE-specific search spaces).

[0072] A carrier may be associated with a particular bandwidth of a radio frequency spectrum, and in some examples, the carrier bandwidth may be referred to as the "system bandwidth" of the carrier or wireless communication system 100. For example, the bandwidth may be one of a number of predetermined bandwidths of a carrier for a particular radio access technology (e.g., 1.4, 3, 5, 10, 15, 20, 40, or 80 MHz). In some examples, each served UE 115 may be configured to operate on part or all of the carrier bandwidth. In other examples, some UEs 115 may be configured to operate using a narrowband protocol type associated with a predefined portion or range (e.g., a set of subcarriers or RBs) within a carrier (e.g., an "in-band" deployment of a narrowband protocol type).

[0073] In a system using MCM technology, a resource element may include a symbol period (e.g., the duration of a modulation symbol) and a subcarrier, where the symbol period and the subcarrier spacing are inversely related. The number of bits carried by each resource element may depend on the modulation scheme (e.g., the order of the modulation scheme). Therefore, the more resource elements received by UE 115 and the higher the order of the modulation scheme, the higher the data rate may be for UE 115. In a MIMO system, wireless communication resources may refer to a combination of radio frequency spectrum resources, time resources, and space resources (e.g., space layers), and the use of multiple space layers may further increase the data rate for communication with UE 115.

[0074] A device (e.g., base station 105 or UE 115) of wireless communication system 100 may have a hardware configuration that supports communication on a specific carrier bandwidth, or may be configurable to support communication on one of a set of carrier bandwidths. In some examples, wireless communication system 100 may include base station 105 and / or UE 115 that may support simultaneous communication via carriers associated with more than one different carrier bandwidths.

[0075] The wireless communication system 100 may support communication with the UE 115 on multiple cells or carriers, a feature that may be referred to as carrier aggregation (CA) or multi-carrier operation. Depending on the carrier aggregation configuration, the UE 115 may be configured with multiple downstream CCs and one or more upstream CCs. Carrier aggregation may be used with both FDD and TDD component carriers.

[0076] In some cases, the wireless communication system 100 can utilize an enhanced component carrier (eCC). An eCC may be characterized by one or more characteristics, including a wider carrier or frequency channel bandwidth, a shorter symbol duration, a shorter TTI duration, or a modified control channel configuration. In some cases, an eCC can be associated with a carrier aggregation configuration or a dual connectivity configuration (e.g., when multiple serving cells have suboptimal or non-ideal backhaul links). An eCC can also be configured for use in an unlicensed spectrum or a shared spectrum (e.g., where more than one operator is allowed to use the spectrum). An eCC characterized by a wide carrier bandwidth can include one or more segments that can be utilized by a UE 115 that cannot monitor the entire carrier bandwidth or is otherwise configured to use a limited carrier bandwidth (e.g., to save power).

[0077] In some cases, an eCC may utilize a different symbol duration than other CCs, which may include the use of a reduced symbol duration compared to the symbol duration of other CCs. A shorter symbol duration may be associated with an increased spacing between adjacent subcarriers. A device utilizing an eCC (such as a UE 115 or a base station 105) may transmit a wideband signal (e.g., according to a frequency channel or carrier bandwidth of 20, 40, 60, 80 MHz, etc.) with a reduced symbol duration (e.g., 16.67 microseconds). A TTI in an eCC may include one or more symbol periods. In some cases, the TTI duration (i.e., the number of symbol periods in a TTI) may be variable.

[0078] Wireless communication systems such as NR systems can utilize any combination of licensed, shared, and unlicensed spectrum bands, among others. Flexibility in eCC symbol duration and subcarrier spacing can allow for the use of eCCs across multiple spectrums. In some examples, NR shared spectrum can improve spectrum utilization and spectrum efficiency, particularly through dynamic vertical (e.g., across the frequency domain) and horizontal (e.g., across the time domain) sharing of resources.

[0079] In some cases, the wireless communication system 100 may be a terrestrial network or be associated with a terrestrial network. Some examples of terrestrial networks may include NR systems, for example, including base stations 105 and UEs 115. In an NR system, an upstream transmission (e.g., a CP-OFDM or DFT-S-OFDM waveform) may arrive at the base station 105 from the UE 115 within an interval time (e.g., within a CP duration). For a subcarrier spacing of 120kHz, the CP duration may be approximately 0.59μs. In addition, the subcarrier spacing for mmW communications in the Ka band (such as downstream transmissions between approximately 20GHz and 30GHz) may be larger than that for upstream transmissions. For example, due to frequency errors caused by Doppler, a subcarrier spacing greater than 120kHz may improve communication reliability. In this example, a subcarrier spacing greater than 120kHz may result in a CP duration of 0.25μs.

[0080] In some examples, the wireless communication system 100 may additionally or alternatively be or be associated with a non-terrestrial network. For example, the base station 105 may utilize a satellite 140 to relay communications to the UE 115. Due to the mobility of the satellite 140 and the distance from the satellite 140 to the UE 115, the communications may experience upstream timing errors (e.g., downstream timing tracking errors, changes in propagation delays). For example, the satellite 140 may be a non-geosynchronous satellite that may orbit the UE 115 from 600 km and travel at a speed of approximately 7.6 km / s. As a result, the round trip time (e.g., update rate) between the satellite 140 and the UE 115 may change by as much as 50 μs per second.

[0081] For example, assuming that the upstream timing is perfect at time t (e.g., no timing adjustment is applied to time i), approximately 10 ms later, the upstream timing error may be approximately 0.5 μs. As a result, the round trip time to satellite 140 may be approximately 30 ms, and the timing advance command calculated based on the upstream transmission at time t may be off by 1.5 μs when it arrives at UE 115. To compensate for the upstream timing error, base station 105 (also referred to as a "gateway") may provide a timing command to UE 115 for the upstream transmission. UE 115 may receive the timing command and send an upstream transmission to base station 105 using the timing adjustment indicated in the timing command.

[0082] According to one or more aspects of the present disclosure, each of the UEs 115 may include a RACH timing manager 150 to enable use of the RACH procedure in an NTN scenario. Although only one of the UEs 115 is shown with a RACH timing manager 150, the manager 150 may be provided to each of the UEs 115. The RACH timing manager 150 may receive information for estimating a propagation delay between the UE 115 accessed via the satellite 140 and the base station 105. The RACH timing module may also send a physical random access channel (PRACH) preamble to the base station 105 at a user-specific timing advance period prior to a random access channel (RACH) opportunity at the UE 115. The user-specific timing advance period corresponds to the estimated propagation delay.

[0083] According to one or more aspects of the present disclosure, each of the base stations 105 may include a RACH timing manager 160 to enable use of the RACH procedure in an NTN scenario. Although only one of the base stations 105 is shown with a RACH timing manager 160, the manager 160 may be provided to each of the base stations 105. The RACH timing manager 160 may send information to the UE 115 for estimating a propagation delay between the UE 115 and the base station 105 for non-terrestrial communications. The RACH timing manager 160 may also receive a PRACH preamble from the UE 115 at a user-specific timing advance period after the UE 115 sends the PRACH preamble. The user-specific timing advance period corresponds to the estimated propagation delay.

[0084] Figure 2 A block diagram showing a design 200 of a base station 105 and a UE 115 is shown. The base station 105 may be Figure 1 UE 115 may be one of the base stations in Figure 1 The base station 105 may be equipped with T antennas 234a through 234t and the UE 115 may be equipped with R antennas 252a through 252r, where in general T ≥ 1 and R ≥ 1.

[0085] At the base station 105, the transmit processor 220 can receive data from the data source 212 for one or more UEs, select one or more modulation and coding schemes (MCS) for each UE based at least in part on a channel quality indicator (CQI) received from the UE, process (e.g., encode and modulate) data for each UE based at least in part on the MCS selected for the UE, and provide data symbols for all UEs. The transmit processor 220 can also process system information (e.g., for semi-static resource partitioning information (SRPI), etc.) and control information (e.g., CQI requests, grants, upper layer signaling, etc.), and provide overhead symbols and control symbols. The transmit processor 220 can also generate reference symbols for reference signals (e.g., cell-specific reference signals (CRS)) and synchronization signals (e.g., primary synchronization signals (PSS) and secondary synchronization signals (SSS)). The transmit (TX) multiple-input multiple-output (MIMO) processor 230 may perform spatial processing (e.g., precoding) on ​​data symbols, control symbols, overhead symbols, and / or reference symbols, if applicable, and may provide T output symbol streams to T modulators (MOD) 232a to 232t. Each modulator 232 may process a respective output symbol stream (e.g., for OFDM, etc.) to obtain an output sample stream. Each modulator 232 may also process (e.g., convert to analog, amplify, filter, and up-convert) the output sample stream to obtain a downlink signal. The T downlink signals from modulators 232a to 232t may be transmitted via T antennas 234a to 234t, respectively. According to various aspects described in more detail below, synchronization signals may be generated using position coding to convey additional information.

[0086] At UE 115, antennas 252a to 252r can receive downlink signals from base station 105 and / or other base stations, and can provide received signals to demodulators (DEMOD) 254a to 254r, respectively. Each demodulator 254 can condition (e.g., filter, amplify, downconvert, and digitize) the received signal to obtain input samples. Each demodulator 254 can also process the input samples (e.g., for OFDM, etc.) to obtain received symbols. MIMO detector 256 can obtain received symbols from all R demodulators 254a to 254r, perform MIMO detection on the received symbols if applicable, and provide detected symbols. Receive processor 258 can process (e.g., demodulate and decode) the detected symbols, provide decoded data for UE 115 to data sink 260, and provide decoded control information and system information to controller / processor 280. The channel processor may determine reference signal received power (RSRP), received signal strength indicator (RSSI), reference signal received quality (RSRQ), channel quality indicator (CQI), etc. In some aspects, one or more components of the UE 115 may be included within a housing.

[0087] On the uplink, at the UE 115, a transmit processor 264 may receive and process data from a data source 262 and control information from a controller / processor 280 (e.g., for reports including RSRP, RSSI, RSRQ, CQI, etc.). The transmit processor 264 may also generate reference symbols for one or more reference signals. The symbols from the transmit processor 264 may be precoded by a TX MIMO processor 266 (if applicable), further processed by modulators 254a through 254r (e.g., for DFT-s-OFDM, CP-OFDM, etc.), and transmitted to the base station 110. At the base station 110, uplink signals from the UE 115 and other UEs may be received by the antenna 234, processed by the demodulator 254, detected by the MIMO detector 236 (if applicable), and further processed by the receive processor 238 to obtain decoded data and control information transmitted by the UE 115. The receive processor 238 may provide decoded data to a data sink 239 and decoded control information to a controller / processor 240. The base station 105 may include a communication unit 244 and communicate with the network controller 130 via the communication unit 244. The network controller 130 may include a communication unit 294, a controller / processor 290, and a memory 292.

[0088] The controller / processor 240 of the base station 105, the controller / processor 280 of the UE 115, and / or Figure 2Any other components of the system may perform one or more techniques associated with the random access procedure, as described in more detail elsewhere herein. For example, the controller / processor 240 of the base station 105, the controller / processor 280 of the UE 115, and / or Figure 2 Any other component may perform or direct e.g. Fig.12 and Fig.13 The operations of the methods 1200, 1300 and / or other processes described herein may be performed. The memories 242 and 282 may store data and program codes for the base station 105 and the UE 115, respectively. For example, the memory 292 may store the RACH timing manager 160, and the memory 242 may store the RACH timing manager 150. The scheduler 246 may schedule the UE for data transmission on the downlink and / or uplink.

[0089] In some aspects, the UE 120 may include means for receiving, means for sending; means for starting; and means for user entering a sleep state; and means for skipping a RACH opportunity. The base station 105 may include means for receiving; means for sending; means for scheduling; and means for grouping. Such means may include combining Figure 2 One or more components of a UE 115 or base station 105 are described.

[0090] As indicated above, Figure 2 is provided as an example only. Other examples may be Figure 2 The examples described are different.

[0091] Figure 3 An example of a wireless communication system 300 that supports a random access procedure for a non-terrestrial network according to one or more aspects of the present disclosure is shown. In some examples, the wireless communication system 300 can implement aspects of the wireless communication system 100. The wireless communication system 300 can include a base station 105-a, a UE 115-a, and a satellite 140-a, which can be a reference Figure 1 Examples of corresponding devices described. For example, the wireless communication system 300 can be a non-terrestrial network, which can include a base station 105-a, a UE 115-a, and a satellite 140-a. The satellite 140-a can relay communications for a base station (e.g., base station 105-a) and a mobile terminal (e.g., UE 115-a). The base station 105-a can also be referred to as a gateway. The geographic area associated with the transmit beam of the satellite 140-a can be referred to as a beam coverage area 330, and when the UE 115-a is located within the beam coverage area 330, the UE 115-a can communicate with the satellite 140-a.

[0092] The base station 105-a can perform communication procedures (e.g., RRC procedures, such as cell acquisition procedures, random access procedures, RRC connection procedures, RRC configuration procedures) with the UE 115-a. The base station 105-a can be configured with multiple antennas, which can be used for directional transmission or beamforming transmission. As part of the communication process, the base station 105-a can establish a two-way communication link 310 for communication with the UE 115-a. In addition or alternatively, as part of the communication process, the base station 105-a can configure the UE 115-a via RRC signaling using a configuration 315 (e.g., time and frequency resources, reference signal period, indication of the symbol of the time slot used to send the reference signal). Although communication is shown to be performed directly, the present disclosure focuses primarily on when the UE 115-a communicates with the base station 105-a via the satellite 140-a.

[0093] The satellite 140-a may generate satellite information (e.g., ephemeris information) associated with communications between the satellite 140-a, the UE 115-a, and the base station 105-a. For example, the satellite 140-a may determine a propagation delay associated with transmissions between the satellite 140-a, the UE 115-a, and the base station 105-a. In some cases, the propagation delay may be based on a distance d from the satellite 140-a to a point 305 (e.g., a center) of the beam coverage area 330. In other cases, the propagation delay may be a factor of the distance d, which may correspond to a round-trip distance between the base station 105-a and the satellite 140-a. Additionally or alternatively, the propagation delay may be an estimated round-trip delay or a round-trip time between the UE 115-a and the base station 105-a, which may be based at least in part on d and / or 2d. It should be noted that the distance d may not reflect the exact distance from the satellite 140-a to the UE 115-a. For example, UE 115-a may be located at the edge of beam coverage area 330 and may be at a distance from satellite 140-a that is different from d. However, such a difference in distance may be negligible compared to d. Therefore, distance d may be a sufficient representation of the distance from satellite 140-a to UE 115-a. Figure 5 Describes more details about the estimated latency.

[0094] The satellite 140-a may send the satellite information to the base station 105-a and / or the UE 115-a via the wireless communication link 335, and the base station 105-a and / or the UE 115-a may be located within the beam coverage area 330. In some cases, the satellite 140-a may update the satellite information and send it to the base station 105-a and / or the UE 115-a at a preconfigured schedule (e.g., update rate). The preconfigured schedule may be based on the speed of the satellite 140-a. For example, the speed of the satellite 140-a may result in a maximum round-trip time change rate of 50 μs per second. That is, for every second of movement of the satellite 140-a, the round-trip time of the communication between the satellite 140-a and the UE 115-a may change, for example, by 50 μs. The round-trip time change rate may also vary based on the movement of the satellite (e.g., orbiting). In such a case, the satellite 140-a may update the satellite information multiple times per second. Additionally or alternatively, the base station 105-a may transmit the satellite information to the UE 115-a via the bidirectional communication link 310, e.g., as part of the configuration 315. In some cases, the base station 105-a may transmit the satellite information to the UE 115-a based on a preconfigured schedule (e.g., an update rate for the satellite 140-a).

[0095] The satellite information may also include the velocity of the satellite 140-a. The velocity of the satellite 140-a may in some cases be defined or related to the following expression v×cos(α), where α is the angle between the vector of velocity v and the vector of distance d. The UE 115-a may determine the round-trip time rate of change using the velocity of the satellite 140-a. In some cases, the UE 115-a may determine the round-trip time rate of change using the velocity of the satellite 140-a based at least in part on whether the UE 115-a is positioned relative to point 305 of the beam coverage area 230. In some examples, using the velocity of the satellite 140-a, the round-trip time rate of change may be defined by the following expression -2v×cos(α) / c, where α is the angle between the vector of velocity v and the vector of distance d, and c is the speed of light. As such, if the upstream transmission is scheduled to be at time t0 using the timing adjustment t a The actual transmission time by UE 115-a may be t0+t a For a scheduled a +Δt for subsequent upstream transmissions sent without a new timing adjustment provided by base station 105-a, the actual transmission time of UE 115-a may be t a +Δt×(-2v×cos(α) / c).

[0096] When UE 115-a is in discontinuous reception (DRX) mode and in RRC idle or RRC connected, base station 105-a can send downlink control information in certain time and frequency resources (e.g., fixed symbols). Between these time and frequency resources, UE 115-a can enter a lower power state, also referred to as "sleep mode", in order to reduce power consumption and increase battery life for UE 115-a. In RRC idle or RRC connected, UE 115-a can wake up once every few symbols to receive downstream transmissions from base station 105-a and / or satellite 140-a. The gap periods allocated before and after the reference signal transmission can benefit base station 105-a by reducing or eliminating interference between UE 115-a transmissions and transmissions from another neighboring UE.

[0097] Figure 4 An example of a non-terrestrial network supporting a random access procedure for the non-terrestrial network in accordance with one or more aspects of the present disclosure is shown. Figure 4 An alternative network configuration is shown. In this configuration, base station 105-b is located on satellite 140-b. Base station 105-b communicates with core network 130-b via wireless communication link 335. UE 115-b communicates with non-terrestrial base station 105b via wireless communication link 335.

[0098] For non-terrestrial network (NTN) access using 5G NR procedures, the large round-trip delay makes it challenging to reuse the random access procedure as is. Enhancements are expected for NR non-terrestrial networks, especially those with nodes located in low earth orbit (LEO), medium earth orbit (MEO), and geosynchronous orbit (GEO). Such enhancements can also be compatible with high altitude platform stations (HAPS) and air-to-ground (ATG) scenarios. It can be assumed that the earth-fixed tracking area has earth-fixed and mobile cells. That is, the UE is stationary and the satellite is mobile. In some scenarios, a user equipment (UE) with global navigation satellite system (GNSS) capability (such as global positioning system (GPS)) can be assumed.

[0099] Various aspects of the present disclosure provide techniques for aligning random access channel (RACH) opportunities between a UE and a network node, such as an eNB / gNB (also referred to as a base station). Random access is a process for establishing a connection between a UE and a base station. During the random access process, the UE sends a preamble to the base station via the RACH to initiate the establishment of the connection. Upon receiving the preamble, the base station schedules uplink resources for the UE and assigns resources in a random access response (RAR).

[0100] In some aspects of the present disclosure, the UE may estimate propagation delays from the UE to the satellite and from the satellite to the ground base station. In other aspects, the RAR window timing is set based on the downlink (DL) propagation delay. One or more examples include addressing uplink (UL) grant processing in the RAR (e.g., message two (Msg2) of the random access procedure), where in one example, the RAR includes an uplink grant. In this example, message three (Msg3) of the random access procedure may be sent based on the uplink grant of the RAR.

[0101] Figure 5 5 shows an example of a non-terrestrial network including propagation delay according to one or more aspects of the present disclosure. The total one-way propagation delay is equal to the delay (D UE ) plus the delay (D sat If the base station 506 is located at the satellite 504, the total one-way propagation delay is equal to the delay (D UE ). UE 502 may estimate the delay D based on the location information, for example, using a global navigation satellite system (GNSS) capability. UE , but the delay D may not be estimated due to the satellite's speed or the switching of the feeder link sat .exist Figure 5 In the example of FIG. 5 , the satellite moves along trajectory 508 at a speed of 7.5 km / s, which can be predicted by UE 502 based on ephemeris data. UE 502 can estimate its position based on the ephemeris data. The delay for the feeder link can be D sat -Δ sat , where Δ sat is the change in satellite position. Note that when the network node is a satellite 504, e.g. no base station is involved, the propagation delay is only the delay between the satellite 504 and the UE 502.

[0102] Various options are available for UE 502 to estimate the total one-way propagation delay. In one option, UE 502 can estimate the total one-way propagation delay by using a timestamp provided in a synchronization signal block (SSB), a physical broadcast channel (PBCH), and / or a system information broadcast (SIB) message. For example, the timestamp can be provided in a system information block one (SIB1) message and / or an NTN-specific SIB message. The UE can estimate the propagation delay based on the timestamp and the reception time.

[0103] In another option, the UE 502 can estimate the total one-way propagation delay by using a universal time for subframe number (SFN) timing. For example, UTC (Coordinated Universal Time) starting at a specific time can be assigned to system frame number zero (SFN0). The UE 502 can estimate the propagation delay based on the boundary of SFN 0. An indication of whether the cell uses Coordinated Universal Time for SFN timing can be provided in a SIB message. In some aspects, if the base station 506 does not follow a specific time reference, an indication can be provided.

[0104] Figure 6 is a timing diagram illustrating an example random access procedure targeting the same random access channel (RACH) opportunity according to one or more aspects of the present disclosure. Figure 6 The RACH procedure for two UEs (UE 1 and UE 2) is shown, targeting the same RACH timing / opportunity (RO) at the network (e.g., base station (gNB) or gateway) taking into account the GNSS capabilities of each UE (e.g., Figure 6 RO2 in Figure 6 In the example of FIG. 1 , it is assumed that the UE and the base station have synchronized SFN boundaries. Each RO may appear in a time slot based on the gNB timeline or based on the satellite timeline (not shown).

[0105] To enable preamble transmission, in accordance with one or more aspects of the present disclosure, each UE may estimate the SFN of the base station based on satellite ephemeris data and the respective positions of each UE. Each UE may then calculate the one-way propagation delay time (D) between the UE and the base station. Each UE may send a physical random access channel (PRACH) preamble "D" time units before the start of the RACH opportunity on the gNB side. In other words, each UE may pre-compensate for delay when sending its preamble. In one example, the RACH opportunity (RO) of the UE is D time units after the RO of the gNB, and the preamble is sent 2*D time units earlier than the RO of the UE.

[0106] exist Figure 6 In the example, UE 1 sends its preamble (Prem1) at a one-way trip delay (D1) before the next RO (RO2 in this example). Similarly, UE 2 sends its preamble (Prem2) at a one-way trip delay (D2) before the next RO (also RO2 in this example). The base station (e.g., gNB) receives the preambles (Prem 1 and Prem 2) from UE 1 and UE 2 at RO2 and processes the preambles during processing time p1. Each one-way trip delay D1, D2 is also called UE-specific timing advance.

[0107] After sending the preamble while in idle mode, each UE may enter sleep within a time period (also called round trip delay) equal to twice the UE-specific timing advance (e.g., 2*D) according to its paging cycle (e.g., Paging Occurrence (PO) of the gNB). The round trip delay may be with respect to the satellite or the base station. Sleep may begin as long as the preamble is sent in a period called a gap. Figure 6 In the example of , UE 2 enters sleep mode after sending its preamble (Prem 2). If the UE is in RRC_CONNECTED mode, the UE may follow the current discontinuous reception (DRX) state during this time period. In another option, the UE may be considered to be in no active time during this period regardless of the current DRX state. The sleep period ends when the RAR window starts.

[0108] In one or more examples, after receiving the preamble, the base station may start a random access response (RAR) window during which the base station may send a RAR to each UE. According to one or more aspects of the present disclosure, each UE may start a random access response (RAR) reception window at the first physical downlink control channel (PDCCH) opportunity as specified in 3GPPTS 38.213 after twice the UE-specific timing advance (e.g., 2*D) from the end of the random access preamble transmission. If the UE is sleeping, the RAR is received after waking up. Each UE receives all transmitted RARs, but only decodes its own RAR. As Figure 6 As seen in , UE 1 receives its own RAR (RAR1) and a RAR (RAR2) intended for UE 2 during its RAR reception window. UE 2 receives its own RAR (RAR2) and a RAR (RAR1) intended for UE 1 during its RAR reception window.

[0109] Scheduling the physical uplink shared channel (PUSCH) is now discussed. In some aspects, the PUSCH scheduling window for a base station may start a period T after the start of the base station RAR window. In one example, period T is the gap between the RAR window and the earliest PUSCH position for the base station.

[0110] According to one or more aspects of the present disclosure, the period T may be calculated as:

[0111] T = 2*Dmax+RAR window+TA (timing advance),

[0112] Where Dmax is the maximum one-way propagation delay time from any UE to the base station in a given cell. In other words, in one example, Dmax may correspond to the propagation delay of the UE farthest from the base station. Farthest refers to the UE with the longest line of sight to the base station, or the UE with the longest propagation delay relative to the base station. It may be assumed that the timing advance value TA is with respect to the downlink (DL) reference timing. The RAR window may be the duration of the window for receiving and processing the RAR.

[0113] According to one example, the earliest time that the UE can send Msg3 in PUSCH can be D time units before the start of the PUSCH scheduling window. Figure 6 In the example of , UE 1 transmits D1 time units before the start of the PUSCH scheduling window, and UE 2 transmits D2 time units before the start of the PUSCH scheduling window. As a result of delaying the PUSCH scheduling window based on Dmax, all UEs experience the same delay, no matter how far the UE is from the base station. In other aspects of the present disclosure, UEs can be scheduled with random resources, and the UEs can select the best resources, as described in more detail below.

[0114] An alternative solution for scheduling PUSCH is now described. Figure 7 is a timing diagram illustrating an exemplary random access procedure with periodic pre-allocation of physical uplink shared channel (PUSCH) resources according to one or more aspects of the present disclosure. Figure 7 In the example, UE (UE1 and UE2) uses Figure 6 The same timing as described is used to send their preambles (Prem1 and Prem 2) and receive RARs (RAR1 and RAR2). According to one or more aspects of the present disclosure, periodic pre-allocated uplink (UL) (e.g., PUSCH) resources can be used to send Msg3. In one example, the periodic allocation can replace the resources indicated in the RAR message (Msg2). The starting point of the pre-allocated periodic PUSCH resources can be the time (Dmin+TA) delayed by the minimum propagation delay (Dmin) from the end of the RAR message or the RAR window. The parameter Dmin can be the minimum one-way propagation delay time from the UE to the base station in a given cell, in other words, the propagation delay from the closest UE to the base station. In this aspect of the present disclosure, the UE can select the first available resource. The closest refers to the UE with the shortest line of sight to the base station, or the UE with the shortest propagation delay relative to the base station.

[0115] Figure 7 Three sets of periodically pre-allocated uplink (UL) grants are shown. Figure 7In the example, UE 1 transmits its PUSCH (PUSCH 1) based on the second pre-allocated uplink resource among three pre-allocated uplink resources because its latency D1 is relatively short. UE 2 transmits its PUSCH (PUSCH 2) based on the third pre-allocated uplink resource among three pre-allocated uplink grants because its latency D2 is longer than the latency D1 for UE 1.

[0116] In one option, the RAR may indicate the activation of pre-allocated PUSCH resources. The configuration (e.g., periodicity, UL grant information) may be provided in a common configuration via SIB messages and / or dedicated radio resource control (RRC) signaling. In another option, the pre-allocated PUSCH resources may be pre-configured in a common configuration. The common configuration is a configuration that can be shared among multiple UEs and used jointly by multiple UEs.

[0117] In other aspects of the present disclosure, multiple uplink grants may be provided in the RAR (Msg2). Alternatively, the uplink grants in the RAR may be mapped to multiple uplink grants at different resources (e.g., time and frequency resources). These solutions account for the number X of one-way propagation delay times (D1, D2,... DX), where DX = Dmax / X. The starting point of the PUSCH scheduling window may be calculated based on DX. In these aspects, a UE with a one-way propagation delay D (such that D2 < D <= D1) may use the uplink grant corresponding to D1. These solutions are more dynamic than the previously described solutions.

[0118] In still other aspects, the UE may indicate the amount of its delay in its preamble. That is, the preamble may inform the network about UE-specific delay. According to these aspects, the PUSCH may be scheduled according to delay groups. For example, UEs may be grouped according to their respective delays. For example, the preamble may be divided into X groups to account for X one-way propagation delay times (D1, D2,... DX), where DX = Dmax / X. The starting point of the PUSCH scheduling window may be calculated based on the group ID corresponding to the preamble received by the base station. In other words, the preamble may inform the network about the delay. The network may schedule the PUSCH according to the delay groups. In these aspects, a UE with a one-way propagation delay D (such that D2 < D <= D1) may use the preamble group corresponding to D1. These solutions are also more dynamic than some of the previously described solutions.

[0119] Figure 8is a timing diagram illustrating an exemplary random access procedure with a physical uplink shared channel (PUSCH) resource based on propagation delay time according to one or more aspects of the present disclosure. Figure 8 In the example, UE (UE1 and UE2) uses Figure 6 The same timing as described above is used to send their preambles (Prem 1 and Prem 2) and receive RARs (RAR1 and RAR2). Figure 8 , the preamble from UE 1 (Prem 1) corresponds to delay D1, and the preamble for UE 2 (Prem2) corresponds to delay D2. Therefore, UE 1 sends its PUSCH (PUSCH 1) to arrive with the first delay group at 2*D1, and UE 2 sends its PUSCH (PUSCH 2) to arrive with the second delay group at 2*D2.

[0120] According to one or more examples of the present disclosure, all UEs may have the same timing advance instead of a UE-specific timing advance. For example, a delay Dmax may be assigned to each UE. In these aspects, the base station may not receive preambles from all UEs at the same time. Each UE may transmit at its own RACH opportunity (RO). Therefore, the base station may set a preamble reception window to receive preambles from all possible UEs. This option may be used for UEs with or without GNSS capabilities.

[0121] Fig. 9 is a timing diagram illustrating an exemplary random access procedure with UE-specific random access channel (RACH) opportunities and a common physical uplink shared channel (PUSCH) scheduling window according to one or more aspects of the present disclosure. Fig. 9 In , a common timing advance is assigned to each UE. Fig. 9 In the example of , each UE can estimate the base station SFN based on satellite ephemeris data and UE position. The UE then calculates the one-way propagation delay (D) between the UE and the base station. The UE determines its RACH timing in its SFN timing, and sends a preamble code according to the calculated RO in its timing.

[0122] exist Fig. 9 In the example, UE 1 is closest to the base station and thus has the smallest propagation delay (Dmin). UE 1 determines its RO based on Dmin. That is, the RO for UE 1 occurs at time Dmin, after the RO for the base station. Fig. 9A first RO (RO1) for a base station is shown, and the first RO (RO1) for UE 1 occurs at a time Dmin after the RO1 of the base station. Similarly, UE 2 determines its RO based on the propagation delay Dx between UE 2 and the base station. The RO for UE 2 occurs at a time Dx after the RO for the base station. Fig. 9 The first RO (RO1) for the base station and the first RO (RO1) for UE 2 are shown to occur at a time Dx after the RO1 of the base station. UE 3 is farthest from the base station and therefore has the largest propagation delay (Dmax). Similar to UE 1 and UE 2, UE 3 determines its RO based on the propagation delay Dmax between UE 3 and the base station. That is, the RO for UE 3 occurs at a time Dmax after the RO for the base station. Fig. 9 A first RO (RO1) for a base station and a first RO (RO1) for UE 3 occurring a time Dmax after RO1 of the base station are shown.

[0123] Considering the UE's GNSS capability, Fig. 9 An overall view of the RACH process for UE 1 and UE 2 using their own adjusted RACH occasions (RO1) is shown in FIG. The base station may not receive all preambles at once because the UEs send preambles at their own RACH occasions. In this example, the preamble reception window for the base station timeline starts at 2*Dmin after the RACH occasion RO1 in the base station timeline. The duration of the preamble reception window can be twice the difference between Dmax and Dmin, which is 2*(Dmax-Dmin). As a result of the preamble reception window, the base station can receive preambles from UE 1, UE 2, and UE 3.

[0124] In some aspects of the present disclosure, the base station may verify in the PRACH configuration that the preamble reception windows for different RACH occasions do not overlap. For example, the gap between RO1 and RO2 should be larger than the preamble reception window. Otherwise, if the gap between RO1 and RO2 is less than 2*(Dmax-Dx), any individual UE (UEx) does not use RO2, where Dx is the propagation delay for UEx. Fig. 9 In the example shown, UE 1 cannot use RO2 because it is too close to UE 1's RO1, but UE 3 can use its RO2.

[0125] In one example, after transmitting a RACH preamble while the UE is in idle mode, the UE may enter sleep mode within a 2*Dmax period according to its paging cycle (e.g., a paging occasion (PO) of the gNB). After a 2*Dmax delay from the end of the random access preamble transmission, each UE may wake up at the first PDCCH opportunity and start its random access response (RAR) window as specified in 3GPP TS 38.213 [6]. During the RAR window, each UE may receive a RAR for UE 1 (RAR 1), a RAR for UE 2 (RAR 2), and a RAR for UE 3 (RAR 3). However, each UE may only decode its own RAR.

[0126] According to one or more aspects of the present disclosure related to scheduling PUSCH, all PUSCH messages are received simultaneously in this example. Fig. 9 As shown, the PUSCH from UE 1 (PUSCH 1), the PUSCH from UE 2 (PUSCH 2), and the PUSCH from UE 3 (PUSCH 3) all arrive at the start point of the PUSCH scheduling window in the base station timeline.

[0127] exist Fig. 9 In the first option shown, the UE applies the timing advance and transmits in the PUSCH position indicated in the RAR. The base station schedules PUSCH reception at least (TA+2*Dmax) after the end of the RAR in the base station timeline. In some configurations, the configured UE time offset is used instead of the RAR window for calculating when to schedule PUSCH reception. The configured UE time offset may be smaller than the RAR window. The UE with the largest one-way propagation delay may be able to send PUSCH immediately after applying the timing advance. In this option, the UE with the smallest one-way propagation delay may experience a differential delay of at least (Dmax-Dmin).

[0128] According to one or more examples related to scheduling PUSCH, the PUSCH message arrives at different times for each UE.The arrival time of the preamble in the scheduling window controls the scheduling of the PUSCH. Fig.10 is a timing diagram illustrating an exemplary random access procedure with UE-specific random access channel (RACH) opportunities and UE-specific physical uplink shared channel (PUSCH) resources according to one or more aspects of the present disclosure. Fig.10 In the example, the preamble and RAR timing are related to Fig. 9 Same as described. PUSCH timing is different. Fig.10In the example shown, the gNB estimates the one-way propagation delay D based on the arrival time of the random access preamble in the preamble reception window. For example, if the preamble arrives at the beginning of the preamble window, the one-way propagation delay is estimated to be the shortest one-way propagation delay Dmin. The base station schedules resources for the PUSCH based on the propagation delay for each UE. For example, the gNB schedules the PUSCH at least (TA+2*estimated one-way propagation delay) after the end of the RAR in the gNB timeline, as Fig.10 As shown. Therefore, because UE1 is estimated to have the shortest one-way propagation delay, the PUSCH for UE 1 is scheduled first. Because UE 3 is estimated to have the longest one-way propagation delay, the PUSCH for UE3 is scheduled last. In this example, a single uplink grant may have variable timing to account for different propagation delays.

[0129] According to one or more examples of the present disclosure, the base station may not wait until the end of the preamble reception window to send the RAR. Instead, the base station may send a separate RAR in response to each preamble. Thus, each UE has its own timeline. This option can be used for UEs with or without GNSS capabilities.

[0130] Fig.11 is a timing diagram illustrating an exemplary random access procedure with UE-specific random access channel (RACH) opportunities and a random access response (RAR) window based on the UE-specific RACH opportunities according to one or more aspects of the present disclosure. Fig.11 In this option, each UE uses its own RACH opportunity (RO1) and starts the RAR window after its own one-way propagation delay time (Dx). Fig. 9 and Fig.10 For the described option, the preamble reception window for the gNB starts 2*Dmin after the RACH opportunity, and the duration of the preamble window = 2*(Dmax-Dmin). In addition, the gNB verifies in the PRACH configuration that the preamble reception windows for different RACH opportunities do not overlap.

[0131] exist Fig.11 In the example of , the gNB does not wait until the end of the preamble reception window to send the RAR (Msg2). The gNB responds to each preamble individually. For example, UE 1, UE 2, and UE 3 each receive their own RAR at different times. That is, UE 1 receives RAR 1 at a first time, UE 2 receives RAR 2 at a second time, and UE 3 receives RAR 3 at a third time. The gNB sends each RAR when receiving and processing each preamble.

[0132] According to this aspect of the present disclosure, the UE may estimate the gNB SFN based on satellite ephemeris data and the UE position. The UE may then calculate the one-way travel time (D) between the UE and the gNB. The UE may determine its RACH opportunity (RO) in its SFN timing. The UE may send a preamble in its RO in its timing. After sending the preamble in idle mode, the UE may go to sleep within a 2*D time period according to its paging cycle (e.g., the gNB's PO). After a 2*D delay from the end of the random access preamble transmission, the UE wakes up at the first PDCCH opportunity and starts a random access response (RAR) window as specified in 3GPP TS 38.213 [6]. In this example, the gNB may send a RAR corresponding to each received PRACH preamble before the preamble reception window expires. The UE may receive an unexpected RAR (e.g., the preamble identifier in the RAR does not belong to the UE). In this case, the UE keeps monitoring the PDCCH for its RAR until the RAR window expires. Unexpected RARs may be received in each of the previously described options, and the same solution applies here as well.

[0133] To schedule PUSCH, the existing procedure for UE to send Msg3 in PUSCH may be applied. However, the gNB may schedule PUSCH at least (TA+2*estimated one-way travel time) after the end of RAR in the gNB timeline.

[0134] Fig.12 is a timing diagram illustrating an example random access procedure targeting the same random access channel (RACH) opportunity and common physical uplink shared channel (PUSCH) scheduling window according to one or more aspects of the present disclosure. Fig.12 The example shown in Figure 6-Figure 9 A combination of options described in Fig.12 In , the satellite operates as a relay between the base station (e.g., gateway (GW) or gNB) and each UE. The propagation delay includes the time delay between the satellite and the UE, and also includes the delay between the satellite and the base station. Fig.12In FIG. 1 , UE 1 and UE 2 send their preambles based on the UE-specific timing advance. UE 1 transmits at time slot x' and UE 2 transmits at time slot x, which corresponds to time slot n of the RO at the base station minus the UE-specific timing advance. The base station (e.g., gateway (GW) / gNB) receives both preambles simultaneously during the RO at time slot n in the base station timeline. The base station sends RAR 1 and RAR 2 at time slot y after receiving the preambles. UE 1 and UE 2 send Msg3 (e.g., PUSCH) at time slot y+k+koffset-UE-specific timing advance, where k is the processing delay and koffset is a scheduling offset greater than the UE-specific timing offset minus k. The base station schedules the reception of Msg3 (e.g., PUSCH) at subframe y+k+koffset. Therefore, Msg3-1 from UE2 and Msg3-1 from UE 1 arrive at the base station at the same time. The messages may be frequency division multiplexed to allow decoding of two messages received simultaneously by the base station.

[0135] One or more aspects of the present disclosure are applicable to UEs with GNSS capabilities. Figure 9-12 The described RACH procedure can also be used for those UEs that do not have GNSS capability to calculate travel time and gNB timeline. In these cases, the UE can start monitoring earlier and for a longer period of time to obtain a timing reference based on the reception time of the SSB; or receive time information (e.g., timestamp) in the SSB so that the UE can calculate the DL propagation delay.

[0136] For preamble transmission, the UE determines its RACH timing (e.g., the transmission time point for the preamble based on the reception timing of the downlink message (such as SSB)) based on the reception timing of the downlink message, so that the gNB receives the preamble within its reception window. For example, for SSB, the timestamp in the SSB or SIB indicates the reception timing of the downlink message. The information is updated for each unit.

[0137] As described above, in some cases, after sending the preamble, all UEs can start the RAR window after 2*Dmax. In other cases, after sending the preamble, all UEs can start the RAR window after 2*Dmin. In these cases, the RAR window is also extended, for example, by the duration of the preamble reception window.

[0138] In one or more examples for scheduling PUSCH, the UE may apply a timing advance (TA) and transmit in the PUSCH location indicated in the RAR (Msg2). The gNB may schedule the PUSCH at least (TA+2*Dmax) after the end of the RAR in the gNB timeline. The UE with the largest one-way propagation delay may transmit the PUSCH after applying the TA. In this example, the UE with the smallest one-way propagation delay suffers a differential delay of at least (Dmax-Dmin).

[0139] If the network can estimate the propagation delay D from the arrival time of the preamble, the gNB can schedule the PUSCH at least (TA+2*D) after the end of the RAR in the gNB timeline. The UE can also estimate the propagation delay D by calculating the gap between the time the preamble is sent and the time the RAR is received. The estimation is possible if the gNB always sends the RAR immediately (or with a fixed processing time) upon receiving the preamble, or if the RAR includes additional information about the gap between the reception of the preamble and the sending of the RAR at the gNB.

[0140] Fig.13 A flow chart illustrating a method 1300 for supporting a random access procedure for a non-terrestrial network in accordance with one or more aspects of the present disclosure is shown. The operations of the method 1300 may be implemented by a UE 115.

[0141] like Fig.13 As shown, in some aspects, method 1300 may include receiving information for estimating a propagation delay between a UE and a network node accessed via non-terrestrial communication (block 1310). For example, the UE (e.g., using antenna 252, demodulator (DEMOD) 254, multiple-input multiple-output (MIMO) detector 256, receive processor 258, controller / processor 280, memory 282, etc.) may receive information for estimating the propagation delay.

[0142] like Fig.13 As shown, in some aspects, the method 1300 may also include sending a physical random access channel (PRACH) preamble to a network node at a user-specific timing advance period before a random access channel (RACH) opportunity at the UE, the user-specific timing advance period corresponding to a propagation delay (block 1320). For example, the UE (e.g., using antenna 252, modulator (MOD) 254, TX MIMO processor 266, transmit processor 264, controller / processor 280, memory 282, etc.) may send the PRACH preamble before the RACH opportunity.

[0143] Optionally, the UE may enter a sleep state (block 1330). For example, the UE (e.g., using the controller / processor 280, the memory 282, etc.) may enter a sleep state. Further optionally, the UE may receive a grant for uplink shared channel resources (block 1340). For example, the UE (e.g., using the antenna 252, the demodulator (DEMOD) 254, the multiple-input multiple-output (MIMO) detector 256, the receive processor 258, the controller / processor 280, the memory 282, etc.) may receive the grant.

[0144] Fig.14 is a diagram illustrating an example method 1400 , for example, performed by a network node (eg, base station 105 ), according to various aspects of the present disclosure.

[0145] like Fig.14 As shown, in some aspects, method 1400 may include sending information for estimating propagation delay between a UE and a network node in a non-terrestrial network to a user equipment (UE) (block 1410). For example, the network node (e.g., using antenna 234, MOD 232, TX MIMO processor 230, transmit processor 220, controller / processor 240, memory 242, etc.) may send information for estimating propagation delay.

[0146] like Fig.14 As shown, in some aspects, method 1400 may also include receiving a physical random access channel (PRACH) preamble from the UE at a user-specific timing advance period after the UE transmits the PRACH preamble, the user-specific timing advance period corresponding to the propagation delay (block 1420). For example, the network node (e.g., using antenna 234, DEMOD 232, MIMO detector 236, receive processor 238, controller / processor 240, memory 242, etc.) may receive the PRACH preamble.

[0147] Optionally, the network node may schedule uplink shared channel resources based on a user-specific timing advance period (block 1430). For example, the network node (e.g., using antenna 234, MOD 232, TX MIMO processor 230, transmit processor 220, controller / processor 240, memory 242, etc.) may schedule uplink shared channel resources after a user-specific timing advance, e.g., periodically or based on a maximum propagation delay.

[0148] Example 1

[0149] A method for wireless communication by a user equipment (UE), comprising: receiving information for estimating a propagation delay between the UE and a network node accessed via non-terrestrial communication; and sending a physical random access channel (PRACH) preamble to the network node at a user-specific timing advance period before a random access channel (RACH) opportunity at the UE, the user-specific timing advance period corresponding to the propagation delay.

[0150] Example 2

[0151] A method according to Example 1, wherein receiving information for estimating includes receiving information for estimating propagation delay based at least in part on timing information included in the system information.

[0152] Example 3

[0153] A method according to any of the preceding examples, wherein receiving information for estimating comprises receiving information for estimating a propagation delay based on a timestamp of a message received from a network node and a reception time of the message, the reception time being based on a reference time obtained from a non-terrestrial network.

[0154] Example 4

[0155] The method according to any of the preceding examples, wherein receiving information for estimating comprises receiving information for estimating a propagation delay based at least in part on satellite ephemeris data and a position of the UE.

[0156] Example 5

[0157] The method according to any of the preceding examples further comprises starting a random access response (RAR) window at a first physical downlink control channel (PDCCH) opportunity after a multiple of the propagation delay from sending the PRACH preamble code.

[0158] Example 6

[0159] The method of Example 5, wherein the multiple duration of the propagation delay between the UE and the network node is twice the duration of the propagation delay between the UE and the network node.

[0160] Example 7

[0161] The method according to any of the preceding examples, wherein the propagation delay comprises a first delay between the UE and the satellite and a second delay between the satellite and the network node.

[0162] Example 8

[0163] The method according to any of the foregoing examples further includes: entering a sleep state after sending the PRACH preamble, the sleep state lasting for a duration that is a multiple of the propagation delay until a random access response (RAR) window starts.

[0164] Example 9

[0165] The method according to any one of Examples 1 to 7 further includes: entering a sleep state after receiving a random access response (RAR) message from the network node until an uplink message is sent.

[0166] Example 10

[0167] A method according to any of the preceding examples, wherein the network node comprises one of a satellite or a base station communicating with the UE via a satellite.

[0168] Example 11

[0169] The method according to any of the foregoing examples further includes: receiving a grant for uplink shared channel resources after a user-specific timing advance period indicated in a random access response (RAR) message, the uplink shared channel being scheduled later than the starting point of the RAR window by a maximum propagation delay of twice plus the time of the RAR window or one of the configured UE time offsets, the maximum propagation delay corresponding to the longest propagation delay for the UE farthest from the network node.

[0170] Example 12

[0171] The method according to any one of Examples 10 further includes: receiving a grant for uplink shared channel resources that occurs periodically after a user-specific timing advance period, the grant being indicated in a random access response (RAR) message.

[0172] Example 13

[0173] A method according to Example 12, wherein the uplink shared channel resources are resources that are periodically scheduled after the end of a RAR message or a random access response (RAR) window is delayed by a minimum propagation delay, the minimum propagation delay corresponding to the minimum propagation delay for a UE closest to the network node.

[0174] Example 14

[0175] The method of Example 12 or Example 13, wherein the RAR message includes multiple uplink grants.

[0176] Example 15

[0177] The method of Example 14, wherein the plurality of uplink grants are based at least in part on a propagation delay.

[0178] Example 16

[0179] The method according to Example 1-Example 11 also includes: receiving a grant for uplink shared channel resources from a network node via radio resource control (RRC) signaling or via a system information block (SIB) or as a general configuration.

[0180] Example 17

[0181] According to the method according to any of the foregoing examples, it also includes: receiving an indication of a grouping for the UE based at least in part on a propagation delay; sending a PRACH preamble code based on the grouping; and receiving uplink shared channel resources in a random access response (RAR) message based on the grouping.

[0182] Example 18

[0183] A method according to any of the foregoing examples, wherein sending the PRACH preamble occurs at a UE-specific RACH opportunity.

[0184] Example 19

[0185] The method according to Example 18 also includes: starting a random access response (RAR) window after a period after sending the PRACH preamble code, and the period for delaying the RAR window includes twice the selected propagation delay plus the duration of the preamble code reception window, and the selected propagation delay corresponds to the shortest propagation delay for the UE closest to the network node, or the propagation delay of the UE corresponds to the arrival of the PRACH preamble code within the preamble code reception window.

[0186] Example 20

[0187] The method of Example 18 further includes starting a random access response (RAR) window at twice a maximum propagation delay after sending the PRACH preamble, the maximum propagation delay corresponding to a longest propagation delay for a UE farthest from the network node.

[0188] Example 21

[0189] The method according to any of the preceding examples, further comprising: skipping a RACH opportunity in response to a gap between two RACH opportunities being less than or equal to a difference between a maximum propagation delay and a propagation delay.

[0190] Example 22

[0191] An apparatus comprising at least one unit for performing the method of any one of Examples 1-21.

[0192] Example 23

[0193] An apparatus for wireless communication, comprising a processor and a memory coupled to the processor, the processor and the memory being configured to perform the method of any one of Examples 1-21.

[0194] Example 24

[0195] A non-transitory computer-readable medium storing code for wireless communication, the code comprising instructions executable by a processor to perform the method of any one of Examples 1-21.

[0196] Example 25

[0197] A method for wireless communication by a network node in a non-terrestrial network (NTN), comprising: sending information for estimating a propagation delay between a user equipment (UE) and the network node; and receiving a physical random access channel (PRACH) preamble from the UE at a user-specific timing advance period after the UE sends the PRACH preamble, the user-specific timing advance period corresponding to the propagation delay.

[0198] Example 26

[0199] A method according to Example 25, wherein the propagation delay includes a first delay between the UE and the satellite and a second delay between the satellite and the network node.

[0200] Example 27

[0201] The method according to any one of Example 25 or Example 26 also includes: scheduling uplink shared channel resources after a user-specific timing advance period, the user-specific timing advance period is indicated in a random access response (RAR) message, and the uplink shared channel is scheduled later than the starting point of the RAR window by twice the maximum propagation delay plus the time of the RAR window or one of the configured UE time offsets, the maximum propagation delay corresponding to the longest propagation delay for the UE farthest from the network node.

[0202] Example 28

[0203] The method according to any one of Examples 25 to 27 further includes: after a random access response (RAR) message or the end of a random access response (RAR) window is delayed by a minimum propagation delay, periodically scheduling uplink shared channel resources after a user-specific timing advance period via a RAR message, the minimum propagation delay corresponding to the shortest propagation delay for a UE closest to the network node.

[0204] Example 29

[0205] The method of Example 28, wherein the RAR message includes a plurality of uplink grants based at least in part on a propagation delay.

[0206] Example 30

[0207] The method according to any one of Example 25 or Example 26 also includes: periodically scheduling uplink shared channel resources via radio resource control (RRC) signaling or via system information block (SIB) or as a general configuration.

[0208] Example 31

[0209] The method according to any one of Examples 25-30 also includes: grouping UEs into preamble groups based at least in part on the propagation delay for each UE; receiving PRACH preambles based on the preamble groups; and scheduling uplink shared channel resources in a random access response (RAR) message based on the preamble groups.

[0210] Example 32

[0211] An apparatus comprising at least one unit for performing the method of any of Examples 25-31.

[0212] Example 33

[0213] An apparatus for wireless communication, comprising a processor and a memory coupled to the processor, the processor and the memory being configured to perform the method of any one of Examples 25-31.

[0214] Example 34

[0215] A non-transitory computer-readable medium storing code for wireless communication, the code comprising instructions executable by a processor to perform the method of any of Examples 25-31.

[0216] It should be noted that the above methods describe possible implementations, and that the operations and steps may be rearranged or otherwise modified, and that other implementations are possible.Furthermore, aspects from two or more of the methods may be combined.

[0217] The technology described herein can be used in various wireless communication systems, such as code division multiple access (CDMA), time division multiple access (TDMA), frequency division multiple access (FDMA), orthogonal frequency division multiple access (OFDMA), single carrier frequency division multiple access (SC-FDMA) and other systems. CDMA systems can implement radio technologies such as CDMA2000, Universal Terrestrial Radio Access (UTRA), etc. CDMA2000 covers IS-2000, IS-95 and IS-856 standards. IS-2000 versions are commonly referred to as CDMA2000 1X, 1X, etc. IS-856 (TIA-856) is commonly referred to as CDMA2000 1xEV-DO, High Rate Packet Data (HRPD), etc. UTRA includes Wideband CDMA (WCDMA) and other variants of CDMA. TDMA systems can implement radio technologies such as Global System for Mobile Communications (GSM).

[0218] OFDMA systems can implement radio technologies such as Ultra Mobile Broadband (UMB), Evolved UTRA (E-UTRA), Institute of Electrical and Electronics Engineers (IEEE) 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802.20, Flash OFDM, etc. UTRA and E-UTRA are parts of Universal Mobile Telecommunications System (UMTS). LTE, LTE-A, and LTE-A Pro are versions of UMTS that use E-UTRA. UTRA, E-UTRA, UMTS, LTE, LTE-A, LTE-A Pro, NR, and GSM are described in documents from an organization named "3rd Generation Partnership Project" (3GPP). CDMA2000 and UMB are described in documents from an organization named "3rd Generation Partnership Project 2" (3GPP2). The technology described herein can be used for the systems and radio technologies mentioned above as well as other systems and radio technologies. Although aspects of LTE, LTE-A, LTE-A Pro, or NR systems may be described for example purposes, and LTE, LTE-A, LTE-A Pro, or NR terminology may be used in much of the description, the techniques described herein are applicable beyond LTE, LTE-A, LTE-A Pro, or NR applications.

[0219] A macro cell typically covers a relatively large geographic area (e.g., a radius of several kilometers) and may allow unrestricted access by a UE 115 with a service subscription to a network provider. A small cell may be associated with a lower power base station 105 than a macro cell, and the small cell may operate in the same or different (e.g., licensed, unlicensed, etc.) frequency band as a macro cell. According to various examples, a small cell may include a pico cell, a femto cell, and a micro cell. A pico cell, for example, may cover a small geographic area and may allow unrestricted access by a UE 115 with a service subscription to a network provider. A femto cell may also cover a small geographic area (e.g., a residence) and may provide restricted access by a UE 115 associated with a femto cell (e.g., a UE 115 in a closed subscriber group (CSG), a UE 115 for a user in a residence, etc.). An eNB for a macro cell may be referred to as a macro eNB. An eNB for a small cell may be referred to as a small cell eNB, a pico eNB, a femto eNB, or a home eNB. An eNB may support one or more (eg, two, three, four, etc.) cells and may support communications using one or more component carriers.

[0220] The described one or more wireless communication systems 100 may support synchronous operation or asynchronous operation. For synchronous operation, the base stations 105 may have similar frame timing, and transmissions from different base stations 105 may be approximately aligned in time. For asynchronous operation, the base stations 105 may have different frame timing, and transmissions from different base stations 105 may not be aligned in time. The techniques described herein may be used for synchronous operation or asynchronous operation.

[0221] Any of a variety of different technologies and techniques may be used to represent the information and signals described herein. For example, data, instructions, commands, information, signals, bits, symbols, and chips referenced throughout the above description may be represented by voltage, current, electromagnetic waves, magnetic fields or particles, optical fields or particles, or any combination thereof.

[0222] The various illustrative blocks and modules described in conjunction with the disclosure herein may be implemented or executed using a general purpose processor, a DSP, an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic device (PLD), discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general purpose processor may be a microprocessor, but in an alternative, the processor may be any conventional processor, controller, microcontroller, or state machine. The processor may also be implemented as a combination of computing devices (e.g., a combination of a DSP and a microprocessor, a plurality of microprocessors, a combination of one or more microprocessors and a DSP core, or any other such configuration).

[0223] The functions described herein may be implemented in hardware, software executed by a processor, firmware, or any combination thereof. If implemented in software executed by a processor, the functions may be stored in a computer-readable medium or transmitted as one or more instructions or codes on a computer-readable medium. Other examples and implementations are within the scope of this disclosure and the appended claims. For example, due to the nature of software, the functions described above may be implemented using software executed by a processor, hardware, firmware, hardwiring, or a combination of any of these items. Features that implement the functions may also be physically located at various locations, including being distributed so that portions of the functions are implemented at different physical locations.

[0224] Computer readable medium includes both non-transitory computer storage medium and communication medium, and communication medium includes any medium that promotes to transmit computer program from one place to another place.Non-transitory storage medium can be any available medium that can be accessed by general-purpose computer or special-purpose computer.By way of example and not limitation, non-transitory computer readable medium can include RAM, ROM, electrically erasable programmable read-only memory (EEPROM), flash memory, compact disk (CD) ROM or other optical disk storage, disk storage or other magnetic storage device, or can be used for carrying or storing the desired program code unit with the form of instruction or data structure and can be accessed by general-purpose computer or special-purpose computer or general processor or special-purpose processor any other non-transitory medium.In addition, any connection is appropriately called computer readable medium.For example, if software is sent from website, server or other remote source using coaxial cable, optical fiber cable, twisted pair, digital subscriber line (DSL) or wireless technology such as infrared, radio and microwave, then coaxial cable, optical fiber cable, twisted pair, DSL or wireless technology such as infrared, radio and microwave are included in the definition of medium. As used herein, disk and disc include CD, laser disc, optical disc, digital versatile disc (DVD), floppy disk and Blu-ray disc, where disks usually reproduce data magnetically, while discs reproduce data optically with lasers. Combinations of the above are also included within the scope of computer-readable media.

[0225] As used herein, including in the claims, "or" used in a list of items (e.g., a list of items ending with a phrase such as "at least one of" or "one or more of") indicates an inclusive list, so that, for example, a list of at least one of A, B, or C means A or B or C or AB or AC or BC or ABC (i.e., A and B and C). In addition, as used herein, the phrase "based on" should not be interpreted as a reference to a closed set of conditions. For example, an exemplary step described as "based on condition A" can be based on both condition A and condition B without departing from the scope of the present disclosure. In other words, as used herein, the phrase "based on" should be interpreted in the same manner as the phrase "based at least in part on."

[0226] In the drawings, similar components or features may have the same reference label. Further, various components of the same type may be distinguished by the reference label followed by a dash and a second label that distinguishes among the similar components. If only the first reference label is used in the specification, the description applies to any of the similar components having the same first reference label, regardless of the second reference label or other subsequent reference labels.

[0227] The description set forth herein in conjunction with the accompanying drawings describes example configurations, and does not represent all examples that may be implemented or within the scope of the claims. The term "exemplary" as used herein means "used as an example, instance, or illustration," rather than "preferred" or "better than other examples." The detailed description includes specific details for providing an understanding of the described techniques. However, these techniques may be practiced without these specific details. In some instances, well-known structures and devices are shown in block diagram form to avoid obscuring the concepts of the described examples.

[0228] This description is provided to enable those skilled in the art to make or use the present disclosure. Various modifications to the present disclosure will be apparent to those skilled in the art, and the general principles defined herein may be applied to other variations without departing from the scope of the present disclosure. Therefore, the present disclosure is not limited to the examples and designs described herein, but is to be given the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for wireless communication by a user equipment (UE), comprising: receiving information for estimating a propagation delay between the UE and a network node accessed via non-terrestrial communications; as well as sending a physical random access channel (PRACH) preamble to the network node at a user-specific timing advance period before a random access channel (RACH) opportunity at the UE, the user-specific timing advance period corresponding to the propagation delay between the UE and the network node; as well as Receiving a grant for an uplink shared channel that is scheduled later than a start of a random access response (RAR) window by two times a maximum propagation delay plus a UE time offset, the maximum propagation delay corresponding to a cell-specific longest propagation delay for a UE farthest from the network node, the maximum propagation delay being the same delay for all UEs within the cell.

2. The method according to claim 1, wherein: The receiving information for estimating the propagation delay between the UE and the network node accessed via the non-terrestrial communication includes receiving information for estimating the propagation delay based at least in part on timing information included in system information.

3. The method according to claim 1, wherein: The receiving information for estimating the propagation delay between the UE and the network node accessed via the non-terrestrial communication includes receiving information for estimating the propagation delay based on a timestamp of a message received from the network node and a reception time of the message, the reception time being based on a reference time obtained from a non-terrestrial network.

4. The method according to claim 1, wherein: The receiving information for estimating the propagation delay between the UE and the network node accessed via the non-terrestrial communication includes receiving information for estimating the propagation delay based at least in part on satellite ephemeris data and a position of the UE.

5. The method according to claim 1, further comprising: A random access response (RAR) window begins at a first physical downlink control channel (PDCCH) opportunity after a duration that is a multiple of the propagation delay from sending the PRACH preamble.

6. The method according to claim 5, wherein: The multiple duration of the propagation delay between the UE and the network node is twice the duration of the propagation delay between the UE and the network node.

7. The method according to claim 1, wherein: The propagation delay includes a first delay between the UE and a satellite and a second delay between the satellite and the network node.

8. The method according to claim 1, further comprising: A sleep state is entered after sending the PRACH preamble, and the sleep state lasts for a duration that is a multiple of the propagation delay until a random access response (RAR) window starts.

9. The method according to claim 1, further comprising: Entering a dormant state after receiving a random access response (RAR) message from the network node until an uplink message is sent.

10. The method according to claim 1, wherein: The network node includes one of a satellite or a base station that communicates with the UE via the satellite.

11. The method according to claim 1, further comprising: A grant for the uplink shared channel is received from the network node via radio resource control (RRC) signaling or via a system information block (SIB) or as a general configuration.

12. The method according to claim 1, further comprising: receiving an indication of a grouping for the UE based at least in part on the propagation delay; Sending a PRACH preamble based on the grouping; as well as The uplink shared channel is received in a random access response (RAR) message based on the grouping.

13. The method according to claim 1, wherein: The transmission of the PRACH preamble occurs at a UE-specific RACH opportunity.

14. The method according to claim 13, further comprising: The random access response (RAR) window is started after a period after sending the PRACH preamble, and the period for delaying the RAR window includes twice a selected propagation delay plus a duration of a preamble reception window, the selected propagation delay corresponding to a shortest propagation delay for a UE closest to the network node, or the propagation delay of the UE corresponds to arrival of the PRACH preamble within the preamble reception window.

15. The method according to claim 13, further comprising: The random access response (RAR) window starts at twice the maximum propagation delay after sending the PRACH preamble.

16. The method according to claim 1, further comprising: One RACH opportunity is skipped in response to a gap between two RACH opportunities being less than or equal to a difference between a maximum propagation delay and the propagation delay.

17. A method for wireless communication by a network node in a non-terrestrial network (NTN), comprising: sending, to a user equipment (UE), information for estimating a propagation delay between the UE and the network node; receiving a physical random access channel (PRACH) preamble from the UE at a user-specific timing advance period after the UE transmits the PRACH preamble, the user-specific timing advance period corresponding to the propagation delay between the UE and the network node; as well as Sending a grant for an uplink shared channel that is scheduled later than a start of a random access response (RAR) window, delayed by two times a maximum propagation delay plus a UE time offset, the maximum propagation delay corresponding to a cell-specific longest propagation delay for a UE farthest from the network node, the maximum propagation delay being the same delay for all UEs within a cell.

18. The method according to claim 17, wherein: The propagation delay includes a first delay between the UE and a satellite and a second delay between the satellite and the network node.

19. The method according to claim 17, further comprising: The uplink shared channel is scheduled periodically via radio resource control (RRC) signaling or via system information block (SIB) or as a common configuration.

20. The method of claim 17, further comprising: grouping the UEs into preamble groups based at least in part on a propagation delay for each UE; receiving the PRACH preamble based on a preamble group; as well as The uplink shared channel is scheduled in a random access response (RAR) message based on the preamble group.

21. An apparatus for wireless communication at a user equipment (UE), comprising: at least one processor; as well as a memory coupled to the processor, the processor and the memory being configured to: receiving information for estimating a propagation delay between the UE and a network node accessed via non-terrestrial communications; sending a physical random access channel (PRACH) preamble to the network node at a user-specific timing advance period before a random access channel (RACH) opportunity at the UE, the user-specific timing advance period corresponding to the propagation delay between the UE and the network node; as well as Receiving a grant for an uplink shared channel that is scheduled later than a start of a random access response (RAR) window by two times a maximum propagation delay plus a UE time offset, the maximum propagation delay corresponding to a cell-specific longest propagation delay for a UE farthest from the network node, the maximum propagation delay being the same delay for all UEs within the cell.

22. An apparatus for wireless communication at a network node in a non-terrestrial network (NTN), comprising: at least one processor; as well as a memory coupled to the processor, the processor and the memory being configured to: sending, to a user equipment (UE), information for estimating a propagation delay between the UE and the network node; receiving a physical random access channel (PRACH) preamble from the UE at a user-specific timing advance period after the UE transmits the PRACH preamble, the user-specific timing advance period corresponding to the propagation delay between the UE and the network node; as well as Sending a grant for an uplink shared channel that is scheduled later than a start of a random access response (RAR) window, delayed by two times a maximum propagation delay plus a UE time offset, the maximum propagation delay corresponding to a cell-specific longest propagation delay for a UE farthest from the network node, the maximum propagation delay being the same delay for all UEs within a cell.

23. A non-transitory computer readable medium having program code recorded thereon, the program code being executed by a processor and comprising program code for: receiving information for estimating a propagation delay between a user equipment (UE) and a network node accessed via non-terrestrial communications; and sending a physical random access channel (PRACH) preamble to the network node at a user-specific timing advance period before a random access channel (RACH) opportunity at the UE, the user-specific timing advance period corresponding to the propagation delay between the UE and the network node; and Receiving a grant for an uplink shared channel that is scheduled later than a start of a random access response (RAR) window by two times a maximum propagation delay plus a UE time offset, the maximum propagation delay corresponding to a cell-specific longest propagation delay for a UE farthest from the network node, the maximum propagation delay being the same delay for all UEs within the cell.

24. A non-transitory computer readable medium having program code recorded thereon, the program code being executed by a processor and comprising program code for: sending, to a user equipment (UE), information for estimating a propagation delay between the UE and the network node; receiving a physical random access channel (PRACH) preamble from the UE at a user-specific timing advance period after the UE transmits the PRACH preamble, the user-specific timing advance period corresponding to the propagation delay between the UE and the network node; and Sending a grant for an uplink shared channel that is scheduled later than a start of a random access response (RAR) window, delayed by two times a maximum propagation delay plus a UE time offset, the maximum propagation delay corresponding to a cell-specific longest propagation delay for a UE farthest from the network node, the maximum propagation delay being the same delay for all UEs within a cell.

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