Method and apparatus for determining uplink transmission timing value of random access channel

Abstract

The application provides a method and device for determining the uplink transmission timing value of a random access channel. The method comprises the following steps: measuring the actual Doppler value and the actual timing value of the SSB signal at the current time; based on the periodic relationship between the SSB signal and the SIB1BIS signal, decoding the SIB1BIS signal according to the actual timing value and the actual Doppler value to obtain satellite trajectory information; obtaining the user terminal coordinates and ephemeris information, and determining the theoretical Doppler value and the theoretical timing value of the SSB signal according to the user terminal coordinates and the satellite trajectory information; calculating the propagation delay of the SSB signal at the current time according to the ephemeris information, the theoretical Doppler value, the theoretical timing value and the actual Doppler value; and determining the uplink transmission timing value of the random access channel at the transmission time according to the propagation delay, the theoretical timing value and the ephemeris information. The application solves the problem that the calculated value of the propagation delay between the low-orbit satellite and the user terminal in the prior art deviates from the actual value, resulting in a large timing deviation of the random access channel.

Description

Technical Field

[0001] This application relates to the field of low-Earth orbit broadband satellite communication technology, and more specifically, to a method, apparatus, computer-readable storage medium, and electronic device for determining the uplink transmission timing value of a random access channel. Background Technology

[0002] With the rapid development of Low Earth Orbit (LEO) broadband satellite communication systems, LEO satellite-based mobile communication networks are gradually becoming an important means of achieving seamless global coverage and high-bandwidth access. In LEO satellite communication systems, user equipment (UE) initiates key operations such as initial connection, uplink synchronization, or resource requests to the satellite through the Physical Random Access Channel (PRACH). The success of the PRACH process directly affects the access performance, latency, and resource utilization efficiency of the entire system.

[0003] However, unlike terrestrial cellular networks, LEO satellites are characterized by high-speed motion (typical orbital speed of approximately 7.5 km / s), dynamically changing propagation delays (one-way propagation delays can reach several milliseconds and change rapidly with orbital position), and significant Doppler shift. These factors make it difficult for the UE to accurately estimate the round-trip propagation delay before sending PRACH, thus making it impossible to accurately compensate for transmission timing. If the PRACH preamble arrives at the satellite receiver at a time deviating from the expected window, it will cause preamble detection failure, increased random access collisions, and even trigger multiple retransmissions, severely impacting system capacity and user experience.

[0004] Current technologies primarily focus on accurately calculating ephemeris information based on satellite trajectory information and UE coordinates for uplink timing pre-compensation, and on accurately tracking uplink timing after initial access. When the calculated propagation delay between the low Earth orbit (LEO) satellite and the user terminal (UE) deviates from the actual value, the PRACH uplink timing pre-compensation calculated based on satellite trajectory information (ephemeris) does not match the actual requirements, resulting in a large PRACH timing deviation. This can negatively impact the reliability of the random access process and system performance. Summary of the Invention

[0005] The main objective of this application is to provide a method, apparatus, computer-readable storage medium, and electronic device for determining the uplink transmission timing value of a random access channel, so as to at least solve the problem of large timing deviation of the random access channel caused by the deviation between the calculated and actual propagation delay between low-Earth orbit satellites and user terminals in the prior art.

[0006] To achieve the above objectives, according to one aspect of this application, a method for determining the uplink transmission timing value of a random access channel is provided, comprising: measuring the actual Doppler value and actual timing value of an SSB signal at a current moment; decoding the SIB1BIS signal based on the periodic relationship between the SSB signal and the SIB1BIS signal, and obtaining satellite trajectory information according to the actual timing value and the actual Doppler value; acquiring user terminal coordinates and ephemeris information; determining the theoretical Doppler value and theoretical timing value of the SSB signal at the current moment based on the user terminal coordinates and the satellite trajectory information; calculating the propagation delay of the SSB signal at the current moment based on the ephemeris information, the theoretical Doppler value, the theoretical timing value, and the actual Doppler value; and determining the uplink transmission timing value of the random access channel at the transmission moment based on the propagation delay, the theoretical timing value, and the ephemeris information.

[0007] Optionally, calculating the propagation delay of the SSB signal at the current moment based at least on the theoretical Doppler value, the theoretical timing value, and the actual Doppler value includes: determining the frequency offset rate and time offset rate of the SSB signal at the current moment based on the ephemeris information; and calculating the propagation delay of the SSB signal at the current moment based on the theoretical Doppler value, the theoretical timing value, the actual Doppler value, the frequency offset rate, and the time offset rate.

[0008] Optionally, calculating the propagation delay of the SSB signal at the current moment based on the theoretical Doppler value, the theoretical timing value, the actual Doppler value, the frequency offset rate of change, and the time offset rate of change includes: calculating the propagation delay of the SSB signal at the current moment according to the first formula: (F1-F0) / B=(T1-T0) / C, where F1 is the theoretical Doppler value, F0 is the actual Doppler value, B is the frequency offset rate of change, T1 is the theoretical timing value, T0 is the propagation delay, and C is the time offset rate of change.

[0009] Optionally, determining the uplink transmission timing value of the random access channel at the transmission time based on the propagation delay, the theoretical timing value, and the ephemeris information includes: determining the ephemeris calculation timing value of the random access channel based on the ephemeris information, and determining the transmission delay value based on the channel information of the random access channel; and determining the uplink transmission timing value of the random access channel at the transmission time based on the ephemeris calculation timing value, the transmission delay value, the propagation delay, and the theoretical timing value.

[0010] Optionally, determining the ephemeris calculation timing value of the random access channel based on the ephemeris information includes: controlling the user terminal to send a random access signal through the random access channel during the uplink random access time period after receiving the SSB signal, so as to determine the time offset between the actual reception of the random access signal by the base station and the theoretical reception of the random access signal, and determining the time offset as the ephemeris calculation timing value.

[0011] Optionally, determining the uplink transmission timing value of the random access channel at the transmission time based on the ephemeris-calculated timing value, the transmission delay value, the propagation delay, and the theoretical timing value includes: determining the uplink transmission timing value of the random access channel at the transmission time according to the second formula: T = Toffset + (T1 - T0) + T2, where T is the uplink transmission timing value, Toffset is the ephemeris-calculated timing value, T2 is the transmission delay value, T1 is the theoretical timing value, and T0 is the propagation delay.

[0012] Optionally, before measuring the actual Doppler value and actual timing value of the SSB signal at the current moment, the method further includes: calibrating the crystal oscillator at the user terminal and the crystal oscillator at the base station using GPS respectively.

[0013] According to another aspect of this application, an apparatus for determining the uplink transmission timing value of a random access channel is provided, comprising: a first determining unit, configured to measure the actual Doppler value and actual timing value of an SSB signal at a current time, and decode the SIB1BIS signal based on the periodic relationship between the SSB signal and the SIB1BIS signal to obtain satellite trajectory information according to the actual timing value and the actual Doppler value; a second determining unit, configured to acquire user terminal coordinates and ephemeris information, and determine the theoretical Doppler value and theoretical timing value of the SSB signal at the current time according to the user terminal coordinates and the satellite trajectory information; and a third determining unit, configured to calculate the propagation delay of the SSB signal at the current time according to the ephemeris information, the theoretical Doppler value, the theoretical timing value and the actual Doppler value, and determine the uplink transmission timing value of the random access channel at the transmission time according to the propagation delay, the theoretical timing value and the ephemeris information.

[0014] According to another aspect of this application, a computer-readable storage medium is provided, the computer-readable storage medium including a stored program, wherein, when the program is executed, it controls the device where the computer-readable storage medium is located to perform any of the methods described above for determining uplink transmission timing values ​​for a random access channel.

[0015] According to another aspect of this application, an electronic device is provided, comprising: one or more processors, a memory, and one or more programs, wherein the one or more programs are stored in the memory and configured to be executed by the one or more processors, the one or more programs including a method for performing any of the methods described above for determining an uplink transmission timing value for a random access channel.

[0016] The technical solution of this application solves the technical problem of insufficient PRACH transmission timing accuracy caused by the high-speed dynamic characteristics of low-Earth orbit satellites. Specifically, by measuring the actual Doppler value and actual timing value of the SSB signal at the current moment, and based on the inherent periodic relationship between the SSB signal and the SIB1BIS signal, the real-time validity of the satellite trajectory information carried by the SIB1BIS signal is accurately determined. Subsequently, by combining the user terminal coordinates and ephemeris information, the theoretical Doppler value and theoretical timing value of the SSB signal at the current moment are calculated. This process compensates for the potential deviation between the ephemeris information and the actual signal propagation characteristics. Furthermore, by comparing and analyzing the actual and theoretical Doppler values, the propagation delay of the SSB signal at the current moment is calculated. This step is crucial for correcting the timing error caused by the high-speed movement of the satellite. Finally, based on the propagation delay, theoretical timing value, and ephemeris information, the accurate uplink transmission timing value of the random access channel at the transmission moment is determined. This uplink timing calculation method based on Doppler value differences effectively improves the transmission accuracy of the PRACH channel, ensures the reliability of uplink synchronization, significantly reduces the access failure rate, and thus optimizes the overall performance of the low-Earth orbit broadband satellite communication system. Especially under conditions where there may be errors between satellite trajectory information and user terminal coordinate information, it can still maintain high accuracy in PRACH transmission, ensuring the effectiveness of base station detection. This solves the problem of large timing deviations in random access channels caused by discrepancies between the theoretical timing values ​​and Doppler frequency shift information between low-Earth orbit satellites and user terminals in existing technologies. Attached Figure Description

[0017] The accompanying drawings, which form part of this application, are used to provide a further understanding of this application. The illustrative embodiments and descriptions of this application are used to explain this application and do not constitute an undue limitation of this application. In the drawings:

[0018] Figure 1 A hardware block diagram of a mobile terminal for performing a method for determining an uplink transmission timing value for a random access channel, according to an embodiment of this application, is shown.

[0019] Figure 2 A flowchart illustrating a method for determining an uplink transmission timing value for a random access channel according to an embodiment of this application is shown.

[0020] Figure 3 A schematic diagram of the channel period intervals for low-Earth orbit satellite communication provided according to an embodiment of this application is shown;

[0021] Figure 4 A structural block diagram of an apparatus for determining the uplink transmission timing value of a random access channel according to an embodiment of this application is shown. Detailed Implementation

[0022] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0023] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort should fall within the scope of protection of the present application.

[0024] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate for the embodiments of this application described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0025] For ease of description, the following explains some of the nouns or terms used in the embodiments of this application:

[0026] SIB1 BIS: This refers to new parameters or enhancements introduced in System Information Block 1 (SIB1) to support NTN scenarios, or more broadly, additional system information blocks (such as SIB19) specifically introduced for NTN. Its core purpose is to provide the terminal (UE) with the critical information required to access the satellite network in order to address the unique challenges of NTN, such as significant propagation delays and satellite mobility.

[0027] PRACH RO (Physical Random Access Channel Occasion) is a fundamental and crucial concept in 5G (NR) and 4G (LTE) networks. It refers to pre-allocated "reservation windows" between the network and terminals (such as mobile phones). When a terminal needs to contact the network (e.g., when a mobile phone is first turned on and wants to access the network), it sends a "reservation request" (i.e., a preamble) at these specific time points and frequency locations.

[0028] PRACH: (Physical Random Access Channel)

[0029] LEO: (Low Earth Orbit) Low Earth orbit.

[0030] UE: (User Equipment) User terminal.

[0031] SSB (Synchronization Signal and PBCH Block) is one of the most critical signal blocks in 5G NR networks. It is the starting point for terminal equipment (UE) to search for the network, achieve downlink synchronization, and obtain key system information after powering on.

[0032] As described in the background section, existing technologies suffer from significant timing deviations in random access channels when the calculated theoretical timing value between a low-Earth orbit satellite and a user terminal deviates from the actual value. To address this issue, embodiments of this application provide a method, apparatus, computer-readable storage medium, and electronic device for determining the uplink transmission timing value of a random access channel.

[0033] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.

[0034] The methods and embodiments provided in this application can be executed on a mobile terminal, computer terminal, or similar computing device. Taking running on a mobile terminal as an example, Figure 1 This is a hardware structure block diagram of a mobile terminal for a method of determining the uplink transmission timing value of a random access channel according to an embodiment of the present invention. Figure 1 As shown, a mobile terminal may include one or more ( Figure 1Only one is shown in the diagram. A processor 102 (which may include, but is not limited to, a microprocessor MCU or a programmable logic device FPGA, etc.) and a memory 104 for storing data are also shown. The mobile terminal may further include a transmission device 106 for communication functions and an input / output device 108. Those skilled in the art will understand that... Figure 1 The structure shown is for illustrative purposes only and does not limit the structure of the mobile terminal described above. For example, the mobile terminal may also include components that are more... Figure 1 The more or fewer components shown, or having the same Figure 1 The different configurations shown.

[0035] Memory 104 can be used to store computer programs, such as application software programs and modules, like the computer program corresponding to the method for determining the uplink transmission timing value of the random access channel in this embodiment of the invention. Processor 102 executes various functional applications and data processing by running the computer program stored in memory 104, thereby implementing the above-described method. Memory 104 may include high-speed random access memory and may also include non-volatile memory, such as one or more magnetic storage devices, flash memory, or other non-volatile solid-state memory. In some instances, memory 104 may further include memory remotely located relative to processor 102, and these remote memories can be connected to the mobile terminal via a network. Examples of the aforementioned networks include, but are not limited to, the Internet, corporate intranets, local area networks, mobile communication networks, and combinations thereof. Transmission device 106 is used to receive or transmit data via a network. Specific examples of the aforementioned networks may include wireless networks provided by the mobile terminal's communication provider. In one example, transmission device 106 includes a Network Interface Controller (NIC), which can be connected to other network devices via a base station to communicate with the Internet. In one example, the transmission device 106 may be a radio frequency (RF) module, which is used to communicate with the Internet wirelessly.

[0036] This embodiment provides a method for determining the uplink transmission timing value of a random access channel, which runs on a mobile terminal, computer terminal, or similar computing device. It should be noted that the steps shown in the flowchart in the accompanying drawings can be executed in a computer system such as a set of computer-executable instructions. Furthermore, although a logical order is shown in the flowchart, in some cases, the steps shown or described may be executed in a different order than that shown here.

[0037] Figure 2 This is a flowchart illustrating a method for determining the uplink transmission timing value of a random access channel according to an embodiment of this application. Figure 2As shown, the method includes the following steps:

[0038] Step S201: Measure the actual Doppler value and actual timing value of the SSB signal at the current moment. Based on the periodic relationship between the SSB signal and the SIB1BIS signal, decode the SIB1BIS signal according to the actual timing value and the actual Doppler value to obtain satellite trajectory information.

[0039] Step S202: Obtain user terminal coordinates and ephemeris information, and determine the theoretical Doppler value and theoretical timing value of the SSB signal at the current moment based on the user terminal coordinates and satellite trajectory information.

[0040] Step S203: Calculate the propagation delay of the SSB signal at the current moment based on the ephemeris information, the theoretical Doppler value, the theoretical timing value, and the actual Doppler value; and determine the uplink transmission timing value of the random access channel at the transmission moment based on the propagation delay, the theoretical timing value, and the ephemeris information.

[0041] This embodiment, by applying steps S201, S202, and S203, solves the technical problem of insufficient PRACH transmission timing accuracy caused by the high-speed dynamic characteristics of low-Earth orbit satellites. Specifically, by measuring the actual Doppler value and actual timing value of the SSB signal at the current moment, and based on the inherent periodic relationship between the SSB signal and the SIB1BIS signal, the real-time validity of the satellite trajectory information carried by the SIB1BIS signal is accurately determined. Subsequently, by combining the user terminal coordinates and ephemeris information, the theoretical Doppler value and theoretical timing value of the SSB signal at the current moment are calculated. This process compensates for the potential deviation between the ephemeris information and the actual signal propagation characteristics. Furthermore, by comparing and analyzing the actual and theoretical Doppler values, the propagation delay of the SSB signal at the current moment is calculated. This step is crucial for correcting timing errors caused by the high-speed movement of the satellite. Finally, based on the propagation delay, theoretical timing value, and ephemeris information, the accurate uplink transmission timing value of the random access channel at the transmission moment is determined. This uplink timing calculation method based on Doppler value differences effectively improves the transmission accuracy of the PRACH channel, ensures the reliability of uplink synchronization, significantly reduces the access failure rate, and thus optimizes the overall performance of the low-Earth orbit broadband satellite communication system. Especially under conditions where there may be errors between satellite trajectory information and user terminal coordinate information, it can still maintain high accuracy in PRACH transmission, ensuring the effectiveness of base station detection. This solves the problem of large timing deviations in random access channels caused by discrepancies between the theoretical timing values ​​and Doppler frequency shift information between low-Earth orbit satellites and user terminals in existing technologies.

[0042] In the specific implementation process, the propagation delay of the SSB signal at the current moment is calculated based on the above-mentioned ephemeris information, the above-mentioned theoretical Doppler value, the above-mentioned theoretical timing value, and the above-mentioned actual Doppler value, including: determining the frequency offset change rate and time offset change rate of the SSB signal at the current moment based on the above-mentioned ephemeris information; and calculating the propagation delay of the SSB signal at the current moment based on the above-mentioned theoretical Doppler value, the above-mentioned theoretical timing value, the above-mentioned actual Doppler value, the above-mentioned frequency offset change rate, and the above-mentioned time offset change rate.

[0043] In this embodiment, the process of calculating the propagation delay of the SSB signal at the current moment based on ephemeris information, theoretical Doppler values, theoretical timing values, and actual Doppler values ​​is as follows: First, the frequency offset rate and timing offset rate of the SSB signal at the current moment are determined based on the ephemeris information. This step is achieved by analyzing the satellite's motion state and the UE's position. Subsequently, based on the theoretical Doppler values, theoretical timing values, actual Doppler values, frequency offset rate, and timing offset rate, a specific mathematical model is used to calculate the propagation delay of the SSB signal at the current moment. Essentially, this calculation step dynamically corrects the theoretical timing value before the UE transmits PRACH, ensuring that even in a high-speed moving environment, the UE can accurately adjust the transmission time of its uplink communication. Through the above precise calculation and timely timing adjustment, the UE can effectively overcome the uncertainty of Doppler frequency offset and theoretical timing value caused by the high-speed movement of the satellite, thereby increasing the probability of the PRACH signal being successfully detected by the base station, reducing the possibility of access failure, and improving the reliability and user experience of the entire low-Earth orbit satellite communication system.

[0044] Specifically, the propagation delay of the SSB signal at the current moment is calculated based on the theoretical Doppler value, the theoretical timing value, the actual Doppler value, the frequency offset rate, and the time offset rate, including: calculating the propagation delay of the SSB signal at the current moment according to the first formula: (F1-F0) / B=(T1-T0) / C, where F1 is the theoretical Doppler value, F0 is the actual Doppler value, B is the frequency offset rate, T1 is the theoretical timing value, T0 is the propagation delay, and C is the time offset rate.

[0045] In this embodiment, the low-Earth orbit broadband satellite communication system calculates the propagation delay T0 of the SSB signal at the current moment by measuring the difference between the actual Doppler value F0 at the current SSB time and the theoretical Doppler value F1 calculated based on the satellite orbit parameters and UE coordinates, combined with the frequency offset rate of change B and the time offset rate of change C, according to the formula (F1-F0) / B=(T1-T0) / C. Here, T1 represents the theoretical timing value calculated based on ephemeris information. Through this calculation, the potential delay error caused by the discrepancy between ephemeris information and actual propagation conditions can be accurately assessed.

[0046] More specifically, determining the uplink transmission timing value of the random access channel at the transmission time based on the aforementioned propagation delay, the aforementioned theoretical timing value, and the aforementioned ephemeris information includes: determining the ephemeris calculation timing value of the random access channel based on the aforementioned ephemeris information, and determining the transmission delay value based on the channel information of the random access channel; and determining the aforementioned uplink transmission timing value of the random access channel at the transmission time based on the aforementioned ephemeris calculation timing value, the aforementioned transmission delay value, the aforementioned propagation delay, and the aforementioned theoretical timing value.

[0047] The length of the random access channel is positively correlated with the transmission delay value, and the transmission delay value is determined based on the length of the random access channel.

[0048] In this embodiment, to improve the transmission timing accuracy of the Physical Random Access Channel (PRACH) in a low-Earth orbit broadband satellite communication system, a method based on downlink signal Doppler frequency offset measurement and ephemeris information difference analysis is adopted. Specifically, firstly, the terminal obtains the actual Doppler value F0 at the current SSB moment by measuring the Synchronization Signal Block (SSB) signal; then, based on the satellite orbit parameters and UE coordinates in the System Information Block (SIB1BIS) immediately following the SSB, the theoretical Doppler value F1 and theoretical timing value T1 at the same SSB location are calculated. Next, by analyzing the difference between F0 and F1, and using the frequency offset change rate B and delay change rate C reflected in the ephemeris information, the actual propagation delay T0 at the SSB moment is calculated. Based on this, combined with the PRACH transmission timing Toffset predicted by the ephemeris, considering the positive constraint of the base station on PRACH timing detection, and the transmission delay value T2 determined according to the PRACH configuration, the accurate PRACH uplink transmission timing value T is finally calculated. This method not only effectively compensates for timing deviations caused by ephemeris information errors or UE coordinate uncertainties, but also adapts to the Doppler effect in high-speed mobile environments, thereby significantly enhancing the PRACH detection success rate and optimizing system performance.

[0049] Further, determining the ephemeris calculation timing value of the random access channel based on the ephemeris information includes: controlling the user terminal to send a random access signal through the random access channel during the uplink random access period after receiving the SSB signal, so as to determine the time offset between the actual reception of the random access signal by the base station and the theoretical reception of the random access signal, and determining the time offset as the ephemeris calculation timing value.

[0050] Furthermore, determining the uplink transmission timing value of the random access channel at the transmission time based on the above-mentioned ephemeris-calculated timing value, the above-mentioned transmission delay value, the above-mentioned propagation delay, and the above-mentioned theoretical timing value includes: determining the uplink transmission timing value of the random access channel at the transmission time according to the second formula: T = Toffset+(T1-T0)+T2, where T is the above-mentioned uplink transmission timing value, Toffset is the above-mentioned ephemeris-calculated timing value, T2 is the above-mentioned transmission delay value, T1 is the above-mentioned theoretical timing value, and T0 is the above-mentioned propagation delay.

[0051] In this embodiment, to improve the timing accuracy of the random access channel (PRACH) transmission in a low-Earth orbit broadband satellite communication system, a compensation method based on the difference between downlink signal Doppler measurement and theoretical ephemeris calculation is adopted. Specifically, firstly, the user terminal (UE) measures the synchronization signal block (SSB) signal through the measurement module to obtain the actual Doppler frequency offset, denoted as F0. Subsequently, based on the satellite orbit parameters obtained from the SIB1BIS and the UE coordinates, the theoretical Doppler frequency offset F1 and the theoretical timing value T1 corresponding to the SSB position are calculated. Next, using the difference between F0 and F1, combined with the frequency offset change rate B and the time offset change rate C calculated from the ephemeris, the propagation delay T0 is calculated through formula conversion. On this basis, when the SSB signal is successfully decoded and immediately enters the subsequent random access opportunity (RO) window, the UE adds the calculated uplink timing advance Toffset, the theoretical and actual timing difference (T1-T0), and the delayed transmission value T2 adjusted according to the PRACH configuration to form the final uplink transmission timing value T. This method can effectively compensate for uplink timing deviations caused by ephemeris information errors or UE location uncertainties, ensuring that the PRACH signal is within the effective detection window at the receiving end, and achieving accurate access even when there are differences in synchronization between the network simulator and the actual network.

[0052] Specifically, before measuring the actual Doppler value and actual timing value of the SSB signal at the current moment, the above method also includes: calibrating the crystal oscillator at the user end and the crystal oscillator at the base station using GPS respectively.

[0053] In this embodiment, to ensure the synchronization accuracy of the signal between the user terminal and the base station, the crystal oscillators of both are calibrated using GPS. This preliminary step is crucial, as it limits the deviation between the crystal oscillators of the user terminal and the base station to a very small range, typically less than 100Hz. This minute deviation is negligible in subsequent Doppler frequency offset measurements, ensuring that the measured frequency offset accurately reflects the relative motion between the satellite and the user terminal. Furthermore, precise calibration of the crystal oscillator enhances the time base consistency of the entire system, providing a solid clock foundation for subsequent calculations and compensation. This significantly improves the accuracy of PRACH transmission timing, reduces the access failure rate caused by clock deviations, and ensures high-precision uplink synchronization even in complex environments with high-speed movement of low-Earth orbit satellites, thus optimizing the overall system performance.

[0054] To enable those skilled in the art to better understand the technical solution of this application, the implementation process of the method for determining the uplink transmission timing value of the random access channel will be described in detail below with reference to specific embodiments.

[0055] This embodiment relates to a specific method for determining the uplink transmission timing value of a random access channel. Figure 3 This is a schematic diagram of the periodic intervals of various channels in low-Earth orbit satellite communication, as shown below. Figure 3 As shown, the interval between SSB and SIB1 BIS is approximately 4.5 ms. Therefore, after decoding SIB1 BIS, the Doppler and timing of the SSB position can be obtained relatively accurately from the satellite trajectory information. The interval between SSB and PRACH is approximately 20 ms. Therefore, the timing of PRACH can be obtained from the accurate timing of the SSB position.

[0056] The specific steps included in this embodiment are as follows:

[0057] Step S1: Measure the actual Doppler value at the current SSB moment;

[0058] S1.1 The base station calibrates its crystal oscillator via GPS, and the UE calibrates its crystal oscillator via GPS or a high-precision clock to ensure that the crystal oscillator deviation between the UE and the base station is less than 100Hz;

[0059] S1.2 The terminal measures the SSB signal through the measurement module to obtain the actual frequency offset of the reference signal. Since the crystal oscillator deviation is very small and can be ignored, the frequency offset value obtained at this time is the Doppler value generated by the relative motion between the satellite and the terminal. This value is recorded as F0.

[0060] Step S2: Calculate the theoretical Doppler value and theoretical timing value at the current SSB time;

[0061] The S2.1 and SSB signals are followed by the SIB1 BIS signal. The satellite trajectory information of the SIB1 BIS can be decoded based on the timing and frequency offset of the SSB signal obtained by measurement.

[0062] S2.2 Based on the satellite orbit parameters in SIB1 BIS and the current or previous coordinates of the UE, the theoretical Doppler F1 and theoretical timing value T1 corresponding to the SSB position can be calculated.

[0063] Step S3: Calculate the propagation delay at the current SSB moment;

[0064] S3.1 The difference between F0 and F1 can be used to deduce that there is a certain calculation difference in the current Doppler value;

[0065] S3.2 According to the formula: (F1-F0) / B=(T1-T0) / C, the propagation delay T0 at the current SSB time is calculated, where B is the current frequency offset change rate calculated from the ephemeris, and C is the current time offset change rate calculated from the ephemeris.

[0066] Step S4: Calculate the uplink timing value for PRACH transmission based on the propagation delay and ephemeris information at the SSB time.

[0067] S4.1 The next RO immediately following the SSB actually sends PRACH, which can ensure the accuracy of timing calculations;

[0068] S4.2 Based on the PRACH transmission timing calculated from the ephemeris, compensate for the difference between T1 and T0;

[0069] S4.3 Since the PRACH timing detected by the base station can only be positive, it is necessary to compensate with another T2. A negative T2 indicates that the PRACH will be sent after a certain delay. The value of T2 is strongly correlated with the PRACH configuration (T2 is positively correlated with the PRACH channel length).

[0070] S4.4, PRACH uplink timing after adding this system:

[0071] T = Toffset (ephemeris calculation value) + (T1-T0) + T2 (value to be sent after delay according to prach configuration), which gives the uplink transmission timing value T of the random access channel at the transmission time.

[0072] This embodiment calculates the difference between the theoretical Doppler value and the measured Doppler value to obtain the actual possible timing value. This timing value is then used to compensate for the timing value calculated from the ephemeris, enabling more accurate PRACH transmission to meet the PRACH transmission timing requirements. Even with a 3-second delay between the channel simulator ephemeris playback and the base station ephemeris trajectory transmission, accurate PRACH transmission can still be guaranteed.

[0073] This application also provides an apparatus for determining the uplink transmission timing value of a random access channel. It should be noted that the apparatus for determining the uplink transmission timing value of a random access channel in this application can be used to execute the method for determining the uplink transmission timing value of a random access channel provided in this application. This apparatus is used to implement the above embodiments and preferred embodiments, and details already described will not be repeated. As used below, the term "module" can refer to a combination of software and / or hardware that implements a predetermined function. Although the apparatus described in the following embodiments is preferably implemented in software, hardware implementation, or a combination of software and hardware, is also possible and contemplated.

[0074] The following describes the apparatus for determining the uplink transmission timing value of a random access channel provided in the embodiments of this application.

[0075] Figure 4 This is a schematic diagram of an apparatus for determining the uplink transmission timing value of a random access channel according to an embodiment of this application. Figure 4 As shown, the device includes:

[0076] The first determining unit 41 is used to measure the actual Doppler value and actual timing value of the SSB signal at the current moment, and based on the periodic relationship between the SSB signal and the SIB1BIS signal, decode the SIB1BIS signal according to the actual timing value and the actual Doppler value to obtain satellite trajectory information.

[0077] The second determining unit 42 is used to acquire user terminal coordinates and ephemeris information, and determine the theoretical Doppler value and theoretical timing value of the SSB signal at the current time based on the user terminal coordinates and the satellite trajectory information.

[0078] The third determining unit 43 is used to calculate the propagation delay of the SSB signal at the current time based on the above ephemeris information, the above theoretical Doppler value, the above theoretical timing value and the above actual Doppler value, and to determine the uplink transmission timing value of the random access channel at the transmission time based on the above propagation delay, the above theoretical timing value and the above ephemeris information.

[0079] In this embodiment, the first determining unit measures the actual Doppler value and actual timing value of the SSB signal at the current moment, and decodes the SIB1BIS signal to obtain satellite trajectory information based on the periodic relationship between the SSB signal and the SIB1BIS signal, according to the actual timing value and actual Doppler value. The second determining unit acquires the user terminal coordinates and ephemeris information, and determines the theoretical Doppler value and theoretical timing value of the SSB signal at the current moment based on the user terminal coordinates and satellite trajectory information. The third determining unit calculates the propagation delay of the SSB signal at the current moment based on the ephemeris information, theoretical Doppler value, theoretical timing value, and actual Doppler value, and determines the uplink transmission timing value of the random access channel at the transmission moment based on the propagation delay, theoretical timing value, and ephemeris information. This solves the technical problem of insufficient PRACH transmission timing accuracy caused by the high-speed dynamic characteristics of low-orbit satellites. Specifically, by measuring the actual Doppler value and actual timing value of the SSB signal at the current moment, and based on the inherent periodic relationship between the SSB signal and the SIB1BIS signal, the real-time validity of the satellite trajectory information carried by the SIB1BIS signal is accurately determined. Subsequently, by combining the user terminal coordinates and ephemeris information, the theoretical Doppler value and theoretical timing value of the SSB signal at the current moment are calculated. This process compensates for the potential deviation between the ephemeris information and the actual signal propagation characteristics. Furthermore, by comparing and analyzing the actual and theoretical Doppler values, the propagation delay of the SSB signal at the current moment is calculated. This step is crucial for correcting timing errors caused by the high-speed movement of the satellite. Finally, based on the propagation delay, theoretical timing value, and ephemeris information, the accurate uplink transmission timing value of the random access channel at the transmission time is determined. This uplink timing value calculation method based on Doppler value differences effectively improves the transmission accuracy of the PRACH channel, ensures the reliability of uplink synchronization, significantly reduces the access failure rate, and thus optimizes the overall performance of the low-Earth orbit broadband satellite communication system. Especially under the condition of possible errors between satellite trajectory information and user terminal coordinate information, it can still maintain high accuracy of PRACH transmission, ensuring the effectiveness of base station detection. This solves the problem of large timing deviations in the random access channel caused by deviations in the theoretical timing value and Doppler frequency shift information between the low-Earth orbit satellite and the user terminal in existing technologies.

[0080] As an optional scheme, the third determining unit includes a first determining module and a first calculating module; the first determining module is used to determine the frequency offset rate and time offset rate of the SSB signal at the current time based on the above ephemeris information; the first calculating module is used to calculate the propagation delay of the SSB signal at the current time based on the above theoretical Doppler value, the above theoretical timing value, the above actual Doppler value, the above frequency offset rate and the above time offset rate.

[0081] In one optional scheme, the first calculation module includes a calculation submodule for calculating the propagation delay of the SSB signal at the current time according to the first formula: (F1-F0) / B=(T1-T0) / C, where F1 is the theoretical Doppler value, F0 is the actual Doppler value, B is the frequency offset rate of change, T1 is the theoretical timing value, T0 is the propagation delay, and C is the time offset rate of change.

[0082] In one optional scheme, the third determining unit includes a second determining module and a third determining module; the second determining module is used to determine the ephemeris calculation timing value of the random access channel based on the ephemeris information, and to determine the transmission delay value based on the channel information of the random access channel; the third determining module is used to determine the uplink transmission timing value of the random access channel at the transmission time based on the ephemeris calculation timing value, the transmission delay value, the propagation delay and the theoretical timing value.

[0083] In one optional scheme, the second determining module includes a first determining submodule, which is used to control the user terminal to send a random access signal through the random access channel during the uplink random access period after receiving the SSB signal, so as to determine the time offset between the actual receipt of the random access signal by the base station and the theoretical receipt of the random access signal, and to determine the time offset as the ephemeris calculation timing value.

[0084] In one optional scheme, the second determining module includes a second determining submodule, used to determine the uplink transmission timing value of the random access channel at the transmission time according to the second formula: T = Toffset+(T1-T0)+T2, where T is the uplink transmission timing value, Toffset is the ephemeris calculation timing value, T2 is the transmission delay value, T1 is the theoretical timing value, and T0 is the propagation delay.

[0085] In an alternative embodiment, the device further includes a calibration processing unit for calibrating the crystal oscillator at the user end and the crystal oscillator at the base station via GPS before measuring the actual Doppler value and actual timing value of the SSB signal at the current moment.

[0086] The aforementioned apparatus for determining the uplink transmission timing value of the random access channel includes a processor and a memory. The first determining unit, the second determining unit, the third determining unit, etc., are all stored as program units in the memory, and the processor executes these program units stored in the memory to implement their respective functions. All of the aforementioned modules are located in the same processor; alternatively, the modules may be located in different processors in any combination.

[0087] The processor contains a kernel, which retrieves the corresponding program units from memory. One or more kernels can be configured, and adjusting kernel parameters can address the problem of significant timing deviations in random access channels caused by discrepancies between the calculated and actual theoretical timing values ​​between low-Earth orbit satellites and user terminals.

[0088] The memory may include non-permanent memory in computer-readable media, such as random access memory (RAM) and / or non-volatile memory, such as read-only memory (ROM) or flash RAM, and the memory includes at least one memory chip.

[0089] This invention provides a computer-readable storage medium including a stored program, wherein, when the program is executed, it controls the device containing the computer-readable storage medium to perform the method for determining the uplink transmission timing value of a random access channel.

[0090] Specifically, methods for determining the uplink transmission timing value of the random access channel include:

[0091] Step S201: Measure the actual Doppler value and actual timing value of the SSB signal at the current moment. Based on the periodic relationship between the SSB signal and the SIB1BIS signal, decode the SIB1BIS signal according to the actual timing value and the actual Doppler value to obtain satellite trajectory information.

[0092] Step S202: Obtain user terminal coordinates and ephemeris information, and determine the theoretical Doppler value and theoretical timing value of the SSB signal at the current moment based on the user terminal coordinates and satellite trajectory information.

[0093] Step S203: Calculate the propagation delay of the SSB signal at the current moment based on the ephemeris information, the theoretical Doppler value, the theoretical timing value, and the actual Doppler value; and determine the uplink transmission timing value of the random access channel at the transmission moment based on the propagation delay, the theoretical timing value, and the ephemeris information.

[0094] This invention provides a processor for running a program, wherein the program executes the method for determining the uplink transmission timing value of a random access channel.

[0095] Specifically, methods for determining the uplink transmission timing value of the random access channel include:

[0096] Step S201: Measure the actual Doppler value and actual timing value of the SSB signal at the current moment. Based on the periodic relationship between the SSB signal and the SIB1BIS signal, decode the SIB1BIS signal according to the actual timing value and the actual Doppler value to obtain satellite trajectory information.

[0097] Step S202: Obtain user terminal coordinates and ephemeris information, and determine the theoretical Doppler value and theoretical timing value of the SSB signal at the current moment based on the user terminal coordinates and satellite trajectory information.

[0098] Step S203: Calculate the propagation delay of the SSB signal at the current moment based on the ephemeris information, the theoretical Doppler value, the theoretical timing value, and the actual Doppler value; and determine the uplink transmission timing value of the random access channel at the transmission moment based on the propagation delay, the theoretical timing value, and the ephemeris information.

[0099] This invention provides an electronic device, which includes a processor, a memory, and a program stored in the memory and executable on the processor. When the processor executes the program, it performs at least the following steps:

[0100] Step S201: Measure the actual Doppler value and actual timing value of the SSB signal at the current moment. Based on the periodic relationship between the SSB signal and the SIB1BIS signal, decode the SIB1BIS signal according to the actual timing value and the actual Doppler value to obtain satellite trajectory information.

[0101] Step S202: Obtain user terminal coordinates and ephemeris information, and determine the theoretical Doppler value and theoretical timing value of the SSB signal at the current moment based on the user terminal coordinates and satellite trajectory information.

[0102] Step S203: Calculate the propagation delay of the SSB signal at the current moment based on the ephemeris information, the theoretical Doppler value, the theoretical timing value, and the actual Doppler value; and determine the uplink transmission timing value of the random access channel at the transmission moment based on the propagation delay, the theoretical timing value, and the ephemeris information.

[0103] The devices mentioned in this article can be servers, PCs, tablets, mobile phones, etc.

[0104] This application also provides a computer program product, which, when executed on a data processing device, is suitable for executing an initialization program having at least the following method steps:

[0105] Step S201: Measure the actual Doppler value and actual timing value of the SSB signal at the current moment. Based on the periodic relationship between the SSB signal and the SIB1BIS signal, decode the SIB1BIS signal according to the actual timing value and the actual Doppler value to obtain satellite trajectory information.

[0106] Step S202: Obtain user terminal coordinates and ephemeris information, and determine the theoretical Doppler value and theoretical timing value of the SSB signal at the current moment based on the user terminal coordinates and satellite trajectory information.

[0107] Step S203: Calculate the propagation delay of the SSB signal at the current moment based on the ephemeris information, the theoretical Doppler value, the theoretical timing value, and the actual Doppler value; and determine the uplink transmission timing value of the random access channel at the transmission moment based on the propagation delay, the theoretical timing value, and the ephemeris information.

[0108] It is obvious to those skilled in the art that the modules or steps of the present invention described above can be implemented using general-purpose computing devices. They can be centralized on a single computing device or distributed across a network of multiple computing devices. They can be implemented using computer-executable program code, and thus can be stored in a storage device for execution by a computing device. In some cases, the steps shown or described can be performed in a different order than those described herein, or they can be fabricated as separate integrated circuit modules, or multiple modules or steps can be fabricated as a single integrated circuit module. Thus, the present invention is not limited to any particular combination of hardware and software.

[0109] Those skilled in the art will understand that embodiments of this application can be provided as methods, systems, or computer program products. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can take the form of a computer program product embodied on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0110] This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart... Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0111] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0112] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0113] In a typical configuration, a computing device includes one or more processors (CPU), input / output interfaces, network interfaces, and memory.

[0114] Memory may include non-persistent memory in computer-readable media, such as random access memory (RAM) and / or non-volatile memory, such as read-only memory (ROM) or flash RAM. Memory is an example of computer-readable media.

[0115] Computer-readable media include both permanent and non-permanent, removable and non-removable media that can store information by any method or technology. Information can be computer-readable instructions, data structures, modules of programs, or other data. Examples of computer storage media include, but are not limited to, phase-change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technologies, CD-ROM, digital versatile optical disc (DVD) or other optical storage, magnetic tape, magnetic disk storage or other magnetic storage devices, or any other non-transferable medium that can be used to store information accessible by a computing device. As defined herein, computer-readable media does not include transient computer-readable media, such as modulated data signals and carrier waves.

[0116] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0117] It should also be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0118] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A method for determining the uplink transmission timing value of a random access channel, characterized in that, include: The actual Doppler value and actual timing value of the SSB signal at the current moment are measured. Based on the periodic relationship between the SSB signal and the SIB1BIS signal, the SIB1BIS signal is decoded according to the actual timing value and the actual Doppler value to obtain satellite trajectory information. Obtain user terminal coordinates and ephemeris information, and determine the theoretical Doppler value and theoretical timing value of the SSB signal at the current time based on the user terminal coordinates and the satellite trajectory information; The propagation delay of the SSB signal at the current moment is calculated based on the ephemeris information, the theoretical Doppler value, the theoretical timing value, and the actual Doppler value. The uplink transmission timing value of the random access channel at the transmission moment is determined based on the propagation delay, the theoretical timing value, and the ephemeris information.

2. The method according to claim 1, characterized in that, The propagation delay of the SSB signal at the current moment is calculated based on the ephemeris information, the theoretical Doppler value, the theoretical timing value, and the actual Doppler value, including: The frequency offset rate and time offset rate of the SSB signal at the current moment are determined based on the ephemeris information. The propagation delay of the SSB signal at the current moment is calculated based on the theoretical Doppler value, the theoretical timing value, the actual Doppler value, the frequency offset rate of change, and the time offset rate of change.

3. The method according to claim 2, characterized in that, The propagation delay of the SSB signal at the current moment is calculated based on the theoretical Doppler value, the theoretical timing value, the actual Doppler value, the frequency offset rate of change, and the time offset rate of change, including: The propagation delay of the SSB signal at the current moment is calculated according to the first formula: (F1-F0) / B=(T1-T0) / C, where F1 is the theoretical Doppler value, F0 is the actual Doppler value, B is the frequency offset rate of change, T1 is the theoretical timing value, T0 is the propagation delay, and C is the time offset rate of change.

4. The method according to claim 1, characterized in that, Determining the uplink transmission timing value of the random access channel at the transmission time based on the propagation delay, the theoretical timing value, and the ephemeris information includes: The ephemeris calculation timing value of the random access channel is determined based on the ephemeris information, and the transmission delay value is determined based on the channel information of the random access channel. The uplink transmission timing value of the random access channel at the transmission time is determined based on the ephemeris calculation timing value, the transmission delay value, the propagation delay, and the theoretical timing value.

5. The method according to claim 4, characterized in that, Determining the ephemeris calculation timing value for the random access channel based on the ephemeris information includes: During the uplink random access period after receiving the SSB signal, the user terminal is controlled to send a random access signal through the random access channel to determine the time offset between the actual reception of the random access signal and the theoretical reception of the random access signal by the base station, and the time offset is determined as the ephemeris calculation timing value.

6. The method according to claim 4, characterized in that, The uplink transmission timing value of the random access channel at the transmission time is determined based on the ephemeris calculation timing value, the transmission delay value, the propagation delay, and the theoretical timing value, including: According to the second formula: T = Toffset+(T1-T0)+T2, the uplink transmission timing value of the random access channel at the transmission time is determined, where T is the uplink transmission timing value, Toffset is the ephemeris calculation timing value, T2 is the transmission delay value, T1 is the theoretical timing value, and T0 is the propagation delay.

7. The method according to claim 1, characterized in that, Before measuring the actual Doppler value and actual timing value of the SSB signal at the current moment, the method further includes: The crystal oscillators at the user end and the base station are calibrated using GPS.

8. An apparatus for determining the uplink transmission timing value of a random access channel, characterized in that, include: The first determining unit is used to measure the actual Doppler value and actual timing value of the SSB signal at the current moment, and based on the periodic relationship between the SSB signal and the SIB1BIS signal, decode the SIB1BIS signal according to the actual timing value and the actual Doppler value to obtain satellite trajectory information; The second determining unit is used to acquire user terminal coordinates and ephemeris information, and determine the theoretical Doppler value and theoretical timing value of the SSB signal at the current time based on the user terminal coordinates and the satellite trajectory information. The third determining unit is used to calculate the propagation delay of the SSB signal at the current time based at least on the theoretical Doppler value, the theoretical timing value and the actual Doppler value, and to determine the uplink transmission timing value of the random access channel at the transmission time based on the propagation delay, the theoretical timing value and the ephemeris information.

9. A computer-readable storage medium, characterized in that, The computer-readable storage medium includes a stored program, wherein, when the program is executed, it controls the device containing the computer-readable storage medium to perform the method for determining the uplink transmission timing value of a random access channel as described in any one of claims 1 to 7.

10. An electronic device, characterized in that, include: One or more processors, a memory, and one or more programs, wherein the one or more programs are stored in the memory and configured to be executed by the one or more processors, the one or more programs including a method for performing the method of determining an uplink transmission timing value for a random access channel as described in any one of claims 1 to 7.

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