Method and system for adjusting timing advance of non-terrestrial network access procedure, and electronic device

Abstract

The application discloses a method and system for adjusting timing advance of NTN access process, and an electronic device. The method comprises the following steps: broadcasting extended PRACH access configuration information in the coverage range of a satellite base station; if an extended random access preamble sequence sent by a satellite terminal based on the extended PRACH access configuration information is received, performing time offset detection on the extended random access preamble sequence according to a detection mode corresponding to a multi-sequence structure format to obtain a time offset parameter; summing the time offset parameter and a conversion parameter determined according to a timing command adjustment coefficient to convert the time offset parameter into an indication value; and sending a random access response message containing the indication value to the satellite terminal, so that the satellite terminal restores the time offset parameter based on the difference between the indication value and the conversion parameter determined according to the timing command adjustment coefficient, and adjusts the timing advance according to the restored time offset parameter. The technical scheme can ensure timing synchronization, thereby ensuring the communication success rate.

Description

Technical Field

[0001] This application relates to the field of communication technology, and in particular to a method, system, and electronic device for adjusting timing advance in the NTN access process. Background Technology

[0002] Non-terrestrial networks (NTNs) refer to wireless networks mounted on satellites or unmanned aircraft systems. Starting with Release 17, the 3GPP standards organization incorporated NTN features into its specifications, making it part of the 5G standard, and continued to enhance it in subsequent versions. Compared to traditional 5G terrestrial communications, NTN offers excellent supplementary services, such as coverage filling, wide-area broadcasting, and support for high-speed mobile users (e.g., user terminals in passenger aircraft). NTN technology utilizes satellite platforms that enable payload pass-through or payload regeneration, generating communication beams and forming elliptical illumination areas to provide service coverage to users. Compared to traditional terrestrial communications, NTN suffers from significant latency due to the vast distance between satellites and the ground. Communication nodes need to pre-compensate for this latency to ensure normal signal transmission and reception.

[0003] In related technologies, during the initial access process between a satellite base station and a satellite terminal, the satellite terminal receives ephemeris information broadcast by the satellite base station and combines it with its own navigation and positioning information to calculate a timing advance to compensate for the significant latency of the satellite-to-ground link. When the satellite terminal needs to connect to the satellite base station, it sends an uplink signal to the satellite base station via the Physical Random Access Channel (PRACH) based on the calculated timing advance. The satellite base station parses the received uplink signal to obtain more refined timing offset parameters and sends these parameters to the satellite terminal via a Random Access Response (RAR) message. The satellite terminal then further adjusts the calculated timing advance based on these parameters. However, according to current communication standards, the timing adjustment for initial access follows the mechanism of the Terrestrial Network (TN) and does not consider the pre-compensation factor of the satellite terminal in the NTN. The timing offset parameters carried by the current RAR can only support positive values. When the timing advance pre-compensated by the satellite terminal is too large, it cannot be used to instruct the satellite terminal to adjust using negative values, which can easily lead to timing asynchrony and communication failure. Summary of the Invention

[0004] This application provides a method, system, electronic device, and readable storage medium for adjusting timing advance during NTN access. Instead of directly transmitting the detected timing offset parameter to the satellite terminal via RAR, the satellite base station determines a conversion parameter according to a pre-agreed timing command adjustment coefficient (implemented through the broadcast extended PRACH access configuration information). This conversion parameter is then used to convert the timing offset parameter by summing it with the conversion parameter determined by the timing command adjustment coefficient, converting the timing offset parameter into an indication value. This indication value is then transmitted to the satellite terminal via RAR. The satellite terminal, based on the difference between this indication value and the conversion parameter determined according to the timing command adjustment coefficient contained in the received extended PRACH access configuration information, restores the indication value to the timing offset parameter detected by the satellite base station. Therefore, the restored timing offset parameter on the satellite terminal side can be represented as both a positive and a negative value. When the timing advance pre-compensated by the satellite terminal is too large, the restored time offset parameter will be negative. The excessive timing advance can be adjusted by using a negative value to ensure timing synchronization and thus ensure communication success rate.

[0005] In a first aspect, embodiments of this application provide a method for adjusting the timing advance of an NTN access process, applied to a satellite base station, the method comprising: The extended PRACH access configuration information is broadcast within the coverage area of ​​the satellite base station. The extended PRACH access configuration information includes a set of extended random access preamble sequences and timing command adjustment coefficients. The extended random access preamble sequence is in a multi-sequence structure format, and the duration of the zero-correlation interval is longer than the duration of the cyclic prefix. If an extended random access preamble sequence is received from a satellite terminal based on the extended PRACH access configuration information, then the extended random access preamble sequence is subjected to time offset detection according to the detection method corresponding to the multi-sequence structure format to obtain a time offset parameter; the time offset parameter is the difference between the round-trip time and the pre-compensated timing advance; the round-trip time is the time it takes for the signal to travel between the satellite base station and the satellite terminal, and the pre-compensated timing advance is the advance of the uplink signal transmission time predetermined by the satellite terminal based on the ephemeris information broadcast by the satellite base station; The time offset parameter is summed with the conversion parameter determined according to the timing command adjustment coefficient to convert the time offset parameter into an indication value; wherein the time offset parameter represents a positive or negative value, and the conversion parameter is a positive value; A random access response message containing the indication value is sent to the satellite terminal so that the satellite terminal can restore the time offset parameter based on the difference between the indication value and the conversion parameter determined according to the timing command adjustment coefficient, and adjust the timing advance according to the restored time offset parameter.

[0006] Optionally, the step of performing time offset detection on the extended random access preamble sequence according to the detection method corresponding to the multi-sequence structure format to obtain time offset parameters includes: Based on the number of repeating sequences indicated by the multi-sequence structure format and the length of a single sequence, time offset detection is performed on the extended random access preamble sequence to obtain the time offset parameter.

[0007] Optionally, the step of performing time offset detection on the extended random access preamble sequence to obtain time offset parameters includes: Determine a plurality of consecutive sequence truncating windows corresponding to the quantity; wherein the length of each sequence truncating window corresponds to the length of the single sequence; Based on the aforementioned several consecutive sequence truncation windows, the extended random access preamble sequence is truncated to obtain the signals contained in each sequence truncation window. Correlation detection is performed on the signals contained in each sequence truncation window to obtain the correlation detection results; The time-biased parameter is determined based on the correlation detection results.

[0008] Optionally, determining the time-biased parameter based on the correlation detection result includes: The validity of the signals contained in each sequence truncation window is determined based on the correlation detection results; the validity includes whether the signal is valid or invalid. The local time offset corresponding to the valid signal is determined based on the correlation detection results corresponding to the valid signal, and the time offset parameter is determined based on the local time offset and the position of the sequence truncation window corresponding to the invalid signal.

[0009] Optionally, the conversion parameters include a default value and a correction parameter; the default value is associated with the number of digits of the indication value; the process of determining the conversion parameters includes: The correction parameter is determined based on the angle between the beam direction of the satellite base station and the motion direction of the satellite base station and the timing command adjustment coefficient; The sum of the default value and the correction parameter is determined as the conversion parameter.

[0010] Secondly, embodiments of this application provide a method for adjusting the timing advance of the NTN access process, applied to a satellite terminal, the method comprising: The system receives extended PRACH access configuration information broadcast by a satellite base station. The extended PRACH access configuration information includes a set of extended random access preamble sequences and timing command adjustment coefficients. The extended random access preamble sequences are in a multi-sequence structure format, and the duration of the zero-correlation interval is longer than the duration of the cyclic prefix. The system acquires the positioning information of the satellite terminal itself and the ephemeris information of the satellite base station, and calculates the timing advance based on the positioning information and the ephemeris information; the timing advance is the advance of the uplink signal transmission time. An extended random access preamble sequence is determined from the set of extended random access preamble sequences, and the extended random access preamble sequence is sent to the satellite base station according to the timing advance. The system receives a random access response message containing an indication value sent by the satellite base station. The indication value is obtained by the satellite base station by summing a time offset parameter with a conversion parameter determined according to the timing command adjustment coefficient. The time offset parameter is obtained by the satellite base station by performing time offset detection on the extended random access preamble sequence, and is the difference between the round-trip time and the timing advance. The round-trip time is the time it takes for the signal to travel between the satellite base station and the satellite terminal. The time offset parameter represents a positive or negative value, and the conversion parameter is a positive value. The time offset parameter is reconstructed based on the difference between the indicated value and the conversion parameter determined according to the timing command adjustment coefficient, and the timing advance is adjusted based on the time offset parameter.

[0011] Optionally, adjusting the timing advance based on the time offset parameter includes: If the time offset parameter is positive, then the sum of the timing advance and the absolute value of the time offset parameter is determined as the new timing advance. If the time offset parameter is negative, the difference between the timing advance and the absolute value of the time offset parameter is determined as the new timing advance.

[0012] Thirdly, embodiments of this application provide a timing advance adjustment system for NTN access procedures, the system including a satellite base station and a satellite terminal; The satellite base station is used to broadcast extended PRACH access configuration information within its coverage area. The extended PRACH access configuration information includes a set of extended random access preamble sequences and timing command adjustment coefficients. If an extended random access preamble sequence sent by the satellite terminal based on the extended PRACH access configuration information is received, the extended random access preamble sequence is subjected to time offset detection according to the detection method corresponding to the multi-sequence structure format to obtain a time offset parameter. The time offset parameter is the difference between the round-trip time and the pre-compensated timing advance. The round-trip time is the time it takes for the signal to travel between the satellite base station and the satellite terminal, and the pre-compensated timing advance is the advance of the uplink signal transmission time predetermined by the satellite terminal based on the ephemeris information broadcast by the satellite base station. The time offset parameter is summed with a conversion parameter determined according to the timing command adjustment coefficients to convert the time offset parameter into an indication value. The time offset parameter represents a positive or negative value, and the conversion parameter is a positive value. A random access response message containing the indication value is sent to the satellite terminal. The satellite terminal is configured to receive the extended PRACH access configuration information broadcast by the satellite base station; acquire its own positioning information and the ephemeris information of the satellite base station, and calculate the timing advance based on the positioning information and the ephemeris information; determine an extended random access preamble sequence from the set of extended random access preamble sequences, and send the extended random access preamble sequence to the satellite base station according to the timing advance; receive the random access response message containing the indication value sent by the satellite base station; restore the timing offset parameter based on the difference between the indication value and the conversion parameter determined according to the timing command adjustment coefficient, and adjust the timing advance based on the timing offset parameter.

[0013] Fourthly, embodiments of this application provide an electronic device, the electronic device including a processor, a memory, and a program or instructions stored in the memory and executable on the processor, wherein the program or instructions, when executed by the processor, implement the method as described in the first or second aspect.

[0014] Fifthly, embodiments of this application provide a readable storage medium on which a program or instructions are stored, which, when executed by a processor, implement the method described in the first or second aspect.

[0015] In this embodiment, during the NTN access process, in addition to the basic PRACH access configuration information, the satellite base station pre-configures a new set of independent PRACH access configuration information, namely extended PRACH access configuration information. This includes a set of extended random access preamble sequences and timing command adjustment coefficients. The extended random access preamble sequence is in a multi-sequence structure format, and the duration of the zero-correlation interval is longer than the duration of the cyclic prefix. The new PRACH access configuration information is broadcast, enabling the satellite terminal to send the extended random access preamble sequence to the satellite base station based on the received extended PRACH access configuration information. If the satellite base station receives the extended random access preamble sequence (instead of the basic random access preamble sequence corresponding to the basic PRACH access configuration information), it performs time offset detection on the extended random access preamble sequence according to the detection method corresponding to the multi-sequence structure format to obtain the time offset parameter. This time offset parameter is the difference between the round-trip time and the timing advance, representing a positive or negative value.

[0016] At this point, the satellite base station does not directly transmit the detected time offset parameter to the satellite terminal via RAR. Instead, it determines the conversion parameter according to the timing command adjustment coefficient pre-agreed with the satellite terminal (this pre-agreed parameter is achieved through the broadcast extended PRACH access configuration information). The time offset parameter is then converted by summing it with the conversion parameter determined by the timing command adjustment coefficient, converting the time offset parameter into an indication value. This indication value is then transmitted to the satellite terminal via RAR. The satellite terminal, based on the difference between this indication value and the conversion parameter determined according to the timing command adjustment coefficient contained in the received extended PRACH access configuration information, restores the indication value to the time offset parameter detected by the satellite base station. Therefore, the restored time offset parameter at the satellite terminal can be represented as either a positive or negative value. When the timing advance pre-compensated by the satellite terminal is too large, the restored time offset parameter will be negative. This negative value can be used to adjust the excessive timing advance, ensuring timing synchronization and thus guaranteeing communication success rate. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of a non-terrestrial network communication scenario in related technologies; Figure 2 This is a flowchart illustrating a method for adjusting the timing advance of an NTN access process according to an embodiment of this application. Figure 3 This is a schematic diagram of a time-off detection scenario according to an embodiment of this application; Figure 4 This application describes an embodiment of an NTN access process timing advance adjustment system; Figure 5This is a schematic diagram of the structure of an electronic device according to an embodiment of this application. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of this application clearer, specific embodiments of this application will be described in further detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are merely for explaining this application and not for limiting it. It should also be noted that, for ease of description, only the parts relevant to this application are shown in the drawings, not all of them. Before discussing exemplary embodiments in more detail, it should be mentioned that some exemplary embodiments are described as processes or methods depicted as flowcharts. Although the flowcharts describe operations (or steps) as sequential processes, many of these operations can be performed in parallel, concurrently, or simultaneously. Furthermore, the order of the operations can be rearranged. The process can be terminated when its operation is completed, but may also have additional steps not included in the drawings. The process can correspond to a method, function, procedure, subroutine, subprogram, etc.

[0019] The technical solutions of the embodiments of this application will be clearly described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application are within the scope of protection of this application.

[0020] The terms "first," "second," etc., used in the specification and claims of this application are used to distinguish similar objects and not to describe a specific order or sequence. It should be understood that such use of data can be interchanged where appropriate so that embodiments of this application can be implemented in orders other than those illustrated or described herein, and the objects distinguished by "first," "second," etc., are generally of the same class and the number of objects is not limited; for example, a first object can be one or more. Furthermore, in the specification and claims, "and / or" indicates at least one of the connected objects, and the character " / " generally indicates that the preceding and following objects are in an "or" relationship.

[0021] The following description, in conjunction with the accompanying drawings, details the method, system, electronic device, and readable storage medium for adjusting the timing advance of the NTN access process provided in this application, through specific embodiments and application scenarios.

[0022] Please see Figure 1 First, we will provide an exemplary introduction to non-terrestrial network communication scenarios in related technologies: like Figure 1 As shown, Figure 1This is a schematic diagram of a non-terrestrial network communication scenario in related technologies. Non-terrestrial networks (NTNs) refer to wireless networks mounted on satellites or unmanned aircraft systems. Compared to traditional 5G terrestrial communication, NTN communication offers excellent supplementary services, such as coverage filling, wide-area broadcasting, and support for high-speed mobile users. NTN technology utilizes satellite platforms that enable payload pass-through or payload regeneration, generating communication beams and forming elliptical illumination areas in the service region to provide service coverage to users. Compared to traditional terrestrial communication, NTN suffers from significant latency due to the vast distance between the satellite and the ground. Communication nodes need to pre-compensate for this significant latency to ensure normal transmission and reception of NTN signals.

[0023] In related technologies, during the initial access process of satellite base stations and satellite terminals, the satellite base station broadcasts system information to the covered satellite terminals. This system information includes NTN configurations such as satellite ephemeris. The satellite terminal receives the ephemeris information broadcast by the satellite base station and combines it with its own navigation and positioning information to calculate a timing advance to compensate for the huge time delay of the satellite-to-ground link between the satellite base station and the satellite terminal. When the satellite terminal needs to connect to the satellite base station, it sends an uplink signal to the satellite base station through the Physical Random Access Channel (PRACH) based on the calculated timing advance. The satellite base station parses the received uplink signal to obtain more refined time offset parameters and sends these time offset parameters to the satellite terminal through a Random Access Response (RAR) message. The satellite terminal further adjusts the calculated timing advance based on these time offset parameters to obtain a new timing advance. Based on the new timing advance, it sends Message 3 signaling to the satellite base station to complete the access.

[0024] However, according to current communication standards, during access via a Terrestrial Network (TN), since the terminal cannot predict its distance from the terrestrial base station antenna, the time at which the terminal transmits uplink signals via PRACH is determined based on the downlink signal reception boundary. It does not perform timing advance (TA) pre-compensation; that is, it does not pre-calculate the timing advance amount. Therefore, the time offset obtained by the TN base station from detecting the uplink signal transmitted by the terminal via PRACH corresponds to the Round-Trip Time (RTT), and the timing advance adjustment amount it sends to the terminal must be a positive number.

[0025] In NTN-based access, because the satellite terminal estimates the propagation delay using ephemeris information and its own navigation and positioning information, the timing of the satellite terminal transmitting uplink signals via PRACH is determined based on the downlink signal reception boundary and a pre-compensated advance (timing advance). The time offset T obtained by the satellite base station from detecting the uplink signal transmitted by the satellite terminal via PRACH corresponds to: (1) Here, TAcomp represents the pre-compensation advance, which is the timing advance calculated by the satellite terminal. When the timing advance calculated by the satellite terminal is too large, the time offset detected by the satellite base station may be negative. However, according to current communication specifications, the timing advance adjustment amount (i.e., the offset parameter) included in the RAR sent by the satellite base station in the current NTN scenario still follows the traditional TN design, only supporting positive values. This is clearly not in line with the characteristics of NTN. According to the current protocol specifications, when the timing advance calculated by the satellite terminal is too large, it is impossible to instruct the satellite terminal to adjust through negative values, which can easily lead to timing asynchrony and communication failure.

[0026] It is worth noting that the above description of non-terrestrial network communication scenarios in related technologies is only an illustrative example. In practical applications, other types of non-terrestrial network communication scenarios may exist, and no specific limitations are made for them.

[0027] To address the aforementioned issues, this application provides a method for adjusting timing advance during NTN access, which can adjust excessive timing advance using negative values ​​to ensure timing synchronization and thus guarantee communication success rate.

[0028] In NTN communication scenarios, during the process of a satellite terminal accessing a satellite base station, the satellite base station instructs the satellite terminal to adjust its timing in advance through various methods. Several embodiments are provided, and one embodiment is described below. For a detailed explanation of the execution process of this embodiment, please refer to [link to relevant documentation]. Figure 2 As shown, Figure 2 This is a flowchart illustrating a method for adjusting the timing advance of an NTN access process according to an embodiment of this application. An embodiment of the method for adjusting the timing advance of an NTN access process provided in this application may include: 201. The satellite base station will broadcast the extended PRACH access configuration information within its coverage area.

[0029] The extended PRACH access configuration information includes a set of extended random access preamble sequences and timing command adjustment coefficients. The extended random access preamble sequences are in a multi-sequence structure format, and the duration of the zero-correlation interval is longer than the duration of the cyclic prefix.

[0030] Satellite base stations can refer to base stations that are partially or entirely located on satellites. Their core function is to generate and transmit wireless signals and provide users with services such as access control and mobility management.

[0031] PRACH can be a special channel used by satellite terminals in the uplink. Its core function is to "knock on the door". Whenever a satellite terminal needs to connect to a satellite base station for the first time, resynchronize, or request uplink resources, it will send a specific "knock on the door" signal (i.e., "random access preamble") to the satellite base station on PRACH to establish communication with the satellite base station.

[0032] Extended PRACH access configuration information can be a set of standardized "access rules" broadcast by the satellite base station to all satellite terminals within its coverage area. These rules can be distributed via System Information Block (SIB1), precisely instructing waiting satellite terminals on when to "knock on the door," specifying the time, frequency band, and format of the random access preamble sequence to use. The goal of extended PRACH access configuration information is to ensure that the initial access of all satellite terminals proceeds in an orderly manner, avoiding signal conflicts.

[0033] It is understandable that the extended PRACH access configuration information is an optional, extended access configuration information based on the traditional basic PRACH access configuration information.

[0034] Satellite terminals that can recognize the extended PRACH access configuration information broadcast by the satellite base station can select that extended PRACH access configuration information to request random access from the satellite base station. Traditional terminals that cannot recognize the extended PRACH access configuration information can still select the basic PRACH access configuration information broadcast by the satellite base station for access, and their basic functions are not affected.

[0035] Both the satellite base station and the satellite terminal select two different detection algorithms and processing procedures—"basic" and "enhanced"—based on the different types of PRACH access configuration information used ("basic" corresponds to basic PRACH access configuration information, and "enhanced" corresponds to extended PRACH access configuration information). If the satellite terminal selects to send MSG1 to the satellite base station based on extended PRACH access configuration information, a new parsing method is used for the TAC command (indication value) of the RAR from the satellite base station (i.e., based on the difference between the indication value and the conversion parameter determined by the timing command adjustment coefficient, and the time offset parameter). Correspondingly, if the satellite base station detects MSG1 in the extended PRACH access configuration information, it uses a new method to determine the RAR's TAC (indication value), that is, summing the time offset parameter with the conversion parameter determined according to the timing command adjustment coefficient to convert the time offset parameter into an indication value.

[0036] The coverage area of ​​a satellite base station can be the maximum geographical area that a satellite signal can project, which can be determined by factors such as the satellite's orbital altitude, antenna design, and beamform.

[0037] Broadcasting can refer to the periodic distribution of System Information Blocks (SIBs) from a satellite base station to all satellite terminals within its coverage area in a one-way, point-to-multipoint manner.

[0038] The extended set of random access preamble sequences can refer to a time-limited "admission cipherbook" issued by the satellite base station to all satellite terminals wishing to access the network. This cipherbook may include configuration parameters such as the Zadoff-Chu (ZC) root sequence index, cyclic shift step size Ncs, and restriction set type. Based on these configuration parameters and according to the ZC sequence generation algorithm specified by 3GPP, the satellite terminal can locally calculate a set containing multiple orthogonal or low-correlation preamble sequences. This set is used by the satellite terminal to randomly select one sequence as Msg1 (the first step in the entire access process) to send on PRACH when initiating random access.

[0039] The timing command adjustment coefficient can refer to the same parameters agreed upon in advance between satellite base stations. It is used to enable the satellite base station or satellite terminal to determine the conversion parameters. On the satellite base station side, the calculated time offset parameter (which may be positive or negative) is converted into an indication value (which takes a positive value) by the conversion parameters determined according to the timing command adjustment coefficient. On the satellite terminal side, the received indication value is restored to the time offset parameter by the conversion parameters determined according to the timing command adjustment coefficient.

[0040] The ephemeris information from satellite base stations can be a precise dataset describing the satellite's position, velocity, and other orbital parameters at a specific reference time (epoch). In NTN's 5G protocol, this precise dataset is the set of parameters used for communication. Due to the long distance and high speed of satellites, satellite terminals cannot rely on real-time feedback from base stations for synchronization as they do in terrestrial networks. Therefore, they need to use the ephemeris broadcast by the satellite base station, combined with their own GNSS positioning information, to autonomously pre-calculate the current propagation delay and Doppler frequency offset.

[0041] Optionally, the satellite base station may broadcast the extended PRACH access configuration information within its coverage area by periodically broadcasting the extended PRACH access configuration information to all satellite terminals within the coverage area via the Broadcast Control Channel (BCCH) through a system information block.

[0042] Optionally, the conversion parameters determined according to the timing command adjustment coefficient may include a default value and a correction parameter; the default value may be associated with the number of digits of the indicated value; the process of determining the conversion parameters may include: determining the correction parameter based on the angle between the beam direction of the satellite base station and the motion direction of the satellite base station and the timing command adjustment coefficient; and determining the conversion parameter by summing the default value and the correction parameter.

[0043] In some embodiments, the default value can be associated with the number of bits of the indicator value in such a way as: determining the default value based on the number of bits of the indicator value specified in the RAR. For example, for a 12-bit indicator value, the value ranges from 0 to 4095, so the midpoint 2048 can be taken as the default value.

[0044] The default value can refer to a preset value that the system automatically adopts when a parameter, variable, or setting is not explicitly specified by the user, upper-level network element, or administrator in the system, protocol, or configuration file.

[0045] The beam direction can be the spatial direction in which the electromagnetic wave energy emitted by the antenna of a satellite base station (spaceborne base station) is concentrated. It determines which area of ​​the Earth's surface the satellite's signal energy is projected onto, and is the basis for forming communication coverage.

[0046] The direction of motion can be the relative motion direction of the satellite base station with respect to the satellite terminal on the ground, which can be characterized by the continuous changes in its azimuth and elevation angles relative to the ground.

[0047] The correction parameter can refer to the parameter used to correct the distance change trend between the satellite base station and the satellite terminal. This distance change trend can be characterized by the angle between the beam direction of the satellite base station and the direction of motion of the satellite base station.

[0048] The following example illustrates the process of a satellite base station broadcasting extended PRACH access configuration information within its coverage area: In addition to the basic PRACH access configuration information (hereinafter defined as the first PRACH access configuration information, i.e., the traditional PRACH resource configuration information), the satellite base station can extend another independent PRACH resource configuration information (defined as the second PRACH access configuration information, i.e., the extended PRACH access configuration information). The second PRACH access configuration information can be configured as optional. When this configuration is present, it means that the satellite base station allows satellite terminals to perform random access through the extended PRACH access configuration information, employing a new timing advance adjustment method during the random access process. In the second PRACH access configuration information, the corresponding PRACH format is limited to a multi-sequence structure, such as formats 1, 2, 3, 4, A1, A2, A3, B1, B2, B3, B4, and C2, etc., and the duration corresponding to the zero-correlation interval can be longer than the cyclic prefix (CP).

[0049] 202. The satellite terminal receives extended PRACH access configuration information broadcast by the satellite base station.

[0050] Optionally, the satellite terminal may receive the extended PRACH access configuration information broadcast by the satellite base station in the following ways: the satellite terminal receives the extended PRACH access configuration information broadcast by the satellite base station on the Physical Downlink Shared Channel (PDSCH).

[0051] 203. The satellite terminal acquires its own positioning information and the ephemeris information of the satellite base station, and calculates the timing advance based on the positioning information and ephemeris information.

[0052] Timing advance is the advance amount for the pre-compensated uplink signal transmission time.

[0053] The positioning information can be either Global Navigation Satellite System (GNSS) positioning information or GPS positioning information.

[0054] Timing advance can refer to the amount of pre-compensation for the time when the satellite terminal sends uplink signals, which is determined based on the delay of the satellite-to-ground link.

[0055] Uplink signals can refer to electromagnetic waves that are transmitted from a satellite terminal to a satellite base station via PRACH, containing data / control information and reference signals. They are used to achieve closed-link management functions such as uplink synchronization, channel quality detection, scheduling requests, and data transmission.

[0056] Optionally, the satellite terminal can obtain its own positioning information and the ephemeris information of the satellite base station, and calculate the timing advance based on the positioning information and the ephemeris information. This can be achieved by the satellite terminal using GNSS to obtain its own precise position, and then combining it with the ephemeris information broadcast by the satellite base station to calculate the RTT between the satellite terminal and the satellite base station. Based on this, the satellite terminal can autonomously determine the timing advance (TA) used for uplink synchronization to achieve pre-compensation for ultra-long transmission delay.

[0057] As an example, a satellite terminal capable of recognizing the second PRACH access configuration information (i.e., the extended PRACH access configuration information mentioned above) can receive and parse the system information broadcast by the satellite base station (including the first and second PRACH access configuration information). When it detects that the second PRACH access configuration information is included, it means that the satellite base station can support the new timing advance adjustment method. Based on this, the satellite terminal capable of recognizing the second PRACH access configuration information preferentially selects the second PRACH access configuration information and sends an extended random access preamble sequence to the satellite base station on the PRACH accordingly. Traditional satellite terminals may not have the ability to recognize the second PRACH access configuration information, and therefore select the traditional first PRACH access configuration information for access.

[0058] 204. The satellite terminal determines the extended random access preamble sequence from the set of extended random access preamble sequences.

[0059] Optionally, the satellite terminal may determine the extended random access preamble sequence from the set of extended random access preamble sequences in the following ways: the satellite terminal may randomly select a random access preamble sequence from the set of extended random access preamble sequences, and the selected random access preamble sequence may be used as the extended random access preamble sequence.

[0060] 205. The satellite terminal sends the extended random access preamble sequence to the satellite base station according to the pre-compensated timing advance.

[0061] Optionally, the method by which the satellite terminal sends the extended random access preamble sequence to the satellite base station according to the pre-compensated timing advance may include: the satellite terminal uses the calculated timing advance (TA) as the reference offset of its own transmission timing to actively compensate for most of the transmission delay, which can be expressed as: PRACH transmission time = downlink reception time - TA, that is, the satellite terminal uses the starting boundary of the received downlink signal as the reference point, subtracts the calculated RTT, and obtains the transmission time of the extended random access preamble sequence (Msg1) so that the extended random access preamble sequence falls exactly within the preset detection window of the satellite base station after spatial propagation.

[0062] 206. If a satellite base station receives an extended random access preamble sequence sent by a satellite terminal based on extended PRACH access configuration information, it performs time offset detection on the extended random access preamble sequence according to the detection method corresponding to the multi-sequence structure format to obtain the time offset parameter.

[0063] The time offset parameter is the difference between the round-trip time and the timing advance; the round-trip time is the time it takes for the signal to travel between the satellite base station and the satellite terminal, and the timing advance is the advance of the uplink signal transmission time determined by the satellite terminal based on ephemeris information.

[0064] Among them, the time offset parameter can refer to the parameter used to adjust the pre-compensation timing advance calculated by the satellite terminal.

[0065] Optionally, the satellite base station performs time offset detection on the extended random access preamble sequence according to the detection method corresponding to the multi-sequence structure format. The method for obtaining the time offset parameters may include: performing time offset detection on the extended random access preamble sequence based on the number of repeating sequences indicated by the multi-sequence structure format and the length of a single sequence to obtain the time offset parameters.

[0066] Optionally, based on the number of repeating sequences indicated by the multi-sequence structure format and the length of a single sequence, time offset detection is performed on the extended random access preamble sequence to obtain the time offset parameters. This can be achieved by: determining several consecutive sequence truncation windows corresponding to the number of repeating sequences indicated by the multi-sequence structure format; wherein the length of each sequence truncation window corresponds to the length of a single sequence; trunculating the extended random access preamble sequence based on the several consecutive sequence truncation windows to obtain the signals contained in each sequence truncation window; performing correlation detection on the signals contained in each sequence truncation window to obtain the correlation detection results; and determining the time offset parameters based on the correlation detection results.

[0067] Optionally, the method for determining the time offset parameter based on the correlation detection result may include: determining the validity of the signal contained in each sequence truncation window based on the correlation detection result; validity includes valid or invalid; determining the local time offset corresponding to the valid signal based on the correlation detection result corresponding to the valid signal, and determining the time offset parameter based on the local time offset and the position of the sequence truncation window corresponding to the invalid signal.

[0068] The following is combined Figure 3 The specific process of the above time offset detection is described by way of example: Please see Figure 3 , Figure 3This is a schematic diagram of a time offset detection scenario according to an embodiment of this application. As an example, for the first PRACH access configuration information mentioned above, the time offset parameters of the uplink signal are obtained using a traditional method, which will not be described in detail here. For the second PRACH access configuration information mentioned above, a multi-sequence detection method is used to obtain the time offset parameters of the uplink signal over a wider range, including negative values.

[0069] like Figure 3 As shown, taking the PRACH format with two consecutive sequence structures as an example, a single extended random access preamble sequence in this case includes at least... Figure 3 The cyclic prefix (CP) + single sequence (SEQ) + single sequence (SEQ) in the formula is... Figure 3 The sequence from the first to the third row is the extended random access preamble sequence. After removing the CP from the extended random access preamble sequence, the satellite base station truncates two consecutive segments of the received signal according to the sequence length for parsing, such as... Figure 3 As shown, the received signal is truncated and parsed according to the CP length: len=CP; single sequence length: len=SEQ. If the timing advance is reasonable and the signal delay does not exceed the CP length, then each truncating window can normally contain a valid received signal (e.g., Figure 3 The first row of the "normal delay sequence" shown is used to obtain the time offset parameter through correlation peak analysis. If the timing advance is too small (e.g., ...), the timing advance will be insufficient. Figure 3 The second row shown is "excessively long delay sequence") or excessively long (such as... Figure 3 The third row shown ("negative delay sequence") indicates that the signal boundary will exceed the CP range, thus a partial truncation window exists (e.g., Figure 3 The window between the dashed lines defined by len=SEQ cannot properly contain a valid received signal, resulting in invalid parsing results for this portion of the captured window.

[0070] Specifically, the detection process of extended random access leader sequences in multi-sequence structures may include the following steps: in each sequence truncation window (e.g. Figure 3 Within the window defined by len=SEQ (shown), correlation detection is performed on the truncated signals to obtain the signal-to-noise ratio (SNR). Using the signal with the highest SNR in each sequence truncated window as a benchmark, the SNR of signals in other sequence truncated windows is judged to meet the benchmark; signals in sequences that do not meet the benchmark are considered invalid. The judgment method can be... The rules are followed, among which , which is the detection threshold; The highest SNR is determined within each sequence truncation window; the local time offset corresponding to the valid signal is calculated based on the detection correlation peak of the valid signal; the global delay, i.e., the time offset parameter, is calculated by combining the local time offsets corresponding to each valid signal and the position of the sequence truncation window corresponding to each invalid signal; within each sequence truncation window, the following parameters are set: A set of windows to be truncated for the front-end sequence where invalid signals occur (e.g.) Figure 3 The second row shown is "excessively delayed sequence" (let's assume...). This is a set of cutoff windows for the back-end sequence where invalid signals occur. and It does not satisfy the condition that both values ​​are greater than 0.

[0071] The timing advance compensation value (timing offset parameter) obtained from the random access preamble sequence for detecting the extended multi-sequence structure is: (2) Where N is the total number of sequence truncating windows. The length of a single sequence in the extended random access preamble sequence, The sequence truncation window includes the local time offset corresponding to the valid signal. This formula shows that when the timing advance at the satellite terminal is too large, it will cause… This situation leads to the premature compensation value. It is negative.

[0072] 207. The satellite base station sums the time offset parameter with the conversion parameter determined according to the timing command adjustment coefficient to convert the time offset parameter into an indication value.

[0073] Among them, the time offset parameter represents a positive or negative value, and the timing command adjustment coefficient is a positive value.

[0074] The indication value can refer to the value of the "Timing AdvanceCommand" field in the RAR sent by the satellite base station. Due to the nature of this field, its value is characterized as a positive value.

[0075] Optionally, the satellite base station may convert the time offset parameter into an indication value by summing the time offset parameter with the conversion parameter determined by the timing command adjustment coefficient. This may include: converting the time offset parameter to a unit, summing it with the conversion parameter determined by the timing command adjustment coefficient, and using the summation result as the indication value.

[0076] 208. The satellite base station sends a random access response message containing an indication value to the satellite terminal.

[0077] After receiving a random access response message containing an indication value, the satellite terminal parses out the indication value, restores the timing offset parameter based on the difference between the indication value and the conversion parameter determined according to the timing command adjustment coefficient, and adjusts the timing advance based on the restored timing offset parameter.

[0078] The random access response message can be the response from the satellite base station to the satellite terminal in the random access process, which is the second step in the entire access process. Therefore, it is usually also called "Msg2".

[0079] Optionally, the satellite base station may send a random access response message containing an indication value to the satellite terminal in the following ways: the satellite base station sends the random access response message containing the indication value to the satellite terminal on the Physical Downlink Shared Channel (PDSCH).

[0080] 209. The satellite terminal reconstructs the time offset parameter based on the difference between the indicated value and the conversion parameter determined according to the timing command adjustment coefficient, and adjusts the timing advance based on the time offset parameter.

[0081] Optionally, the satellite terminal may restore the time offset parameter based on the difference between the indicated value and the conversion parameter determined by the timing command adjustment coefficient. This may include: the satellite terminal may first calculate the difference between the indicated value and the conversion parameter determined by the timing command adjustment coefficient, and then convert the difference to a unit to restore the time offset parameter.

[0082] Optionally, the method of adjusting the timing advance based on the time offset parameter may include: if the time offset parameter is positive, then the sum of the timing advance and the absolute value of the time offset parameter is determined as the new timing advance; if the time offset parameter is negative, then the difference between the timing advance and the absolute value of the time offset parameter is determined as the new timing advance.

[0083] As an example, the MAC sublayer of a satellite base station can set the random access response message based on the time offset detection result of the extended random access preamble sequence reported by the physical layer. If the time offset detection result comes from the second PRACH access configuration information mentioned above, the "Timing Advance Command" field in the random access response message adopts the following new definition. While keeping the existing bit width of this field unchanged at 12 bits, the new definition supports negative value adjustment: (3) (4) in, The value of the "Timing Advance Command" field is set to indicate the timing advance. The conversion parameters are as described above; The instantaneous partial parameter, whose duration and sign are related to the aforementioned timing advance compensation value. Consistent; The parameter set index is a key parameter determined by higher-level parameters, which defines the subcarrier spacing for the corresponding bandwidth portion.

[0084] Conversion parameters The timing command adjustment coefficient can be determined based on the aforementioned timing command adjustment coefficient, which can be synchronized by the satellite base station to the covered satellite terminals through extended system broadcast (synchronized through the second PRACH access configuration information broadcast above). The default value is 2048, which can be optimized according to the beam characteristics of the cell coverage.

[0085] Consider the following two scenarios: When the satellite beam direction is aligned with the satellite's motion direction, the distance between the satellite terminal and the satellite decreases, easily leading to a timing advance that is higher than the actual distance, resulting in a negative time offset detection. Conversely, when the satellite beam direction is opposite to the satellite's motion direction, the distance between the satellite terminal and the satellite increases, easily leading to a timing advance that is lower than the actual distance, resulting in a positive time offset detection. As an example, a correction parameter can be introduced to optimize the conversion parameters. The correction method is as follows: (5) in," The symbols on the left and right sides of the text are for rounding down; It is the maximum adjustment amount (i.e., the adjustment coefficient of the timing command mentioned above). The angle between the beam direction of the satellite base station and the direction of its movement is the angle between the beam direction of the satellite base station and the direction of its movement. This correction method can achieve the following: for coverage areas where the satellite-to-ground distance tends to shorten, more negative adjustment ranges are reserved; for coverage areas where the satellite-to-ground distance tends to lengthen, more positive adjustment ranges are reserved.

[0086] As an example, the satellite terminal adjusts the timing advance based on the timing offset parameter and sends message 3 (Msg3) to the satellite base station according to the adjusted timing advance to complete the subsequent access process.

[0087] In this embodiment, during the NTN access process, in addition to the basic PRACH access configuration information, the satellite base station pre-configures a new set of independent PRACH access configuration information, namely extended PRACH access configuration information. This includes a set of extended random access preamble sequences and timing command adjustment coefficients. The extended random access preamble sequence is in a multi-sequence structure format, and the duration of the zero-correlation interval is longer than the duration of the cyclic prefix. The new PRACH access configuration information is broadcast, enabling the satellite terminal to send the extended random access preamble sequence to the satellite base station based on the received extended PRACH access configuration information. If the satellite base station receives the extended random access preamble sequence (instead of the basic random access preamble sequence corresponding to the basic PRACH access configuration information), it performs time offset detection on the extended random access preamble sequence according to the detection method corresponding to the multi-sequence structure format to obtain the time offset parameter. This time offset parameter is the difference between the round-trip time and the timing advance, representing a positive or negative value.

[0088] At this point, the satellite base station does not directly transmit the detected time offset parameter to the satellite terminal via RAR. Instead, it determines the conversion parameter according to the timing command adjustment coefficient pre-agreed with the satellite terminal (this pre-agreed parameter is achieved through the broadcast extended PRACH access configuration information). The time offset parameter is then converted by summing it with the conversion parameter determined by the timing command adjustment coefficient, converting the time offset parameter into an indication value. This indication value is then transmitted to the satellite terminal via RAR. The satellite terminal, based on the difference between this indication value and the conversion parameter determined according to the timing command adjustment coefficient contained in the received extended PRACH access configuration information, restores the indication value to the time offset parameter detected by the satellite base station. Therefore, the restored time offset parameter at the satellite terminal can be represented as either a positive or negative value. When the timing advance pre-compensated by the satellite terminal is too large, the restored time offset parameter will be negative. This negative value can be used to adjust the excessive timing advance, ensuring timing synchronization and thus guaranteeing communication success rate.

[0089] Corresponding to the above method embodiments, this application also provides a timing advance adjustment system for the NTN access process, such as... Figure 4 As shown, Figure 4 This application describes an NTN access procedure timing advance adjustment system according to one embodiment of the present application. The system includes: a satellite base station 401 and a satellite terminal 402. Satellite base station 401 is used to broadcast extended PRACH access configuration information within its coverage area. The extended PRACH access configuration information includes a set of extended random access preamble sequences and timing command adjustment coefficients. If an extended random access preamble sequence sent by the satellite terminal based on the extended PRACH access configuration information is received, the extended random access preamble sequence is time-biased according to the detection method corresponding to the multi-sequence structure format to obtain a time-bias parameter. The time-bias parameter is the difference between the round-trip time and the pre-compensated timing advance. The round-trip time is the time it takes for the signal to travel between the satellite base station and the satellite terminal, and the pre-compensated timing advance is the advance of the uplink signal transmission time predetermined by the satellite terminal based on the ephemeris information broadcast by the satellite base station. The time-bias parameter is summed with a conversion parameter determined according to the timing command adjustment coefficients to convert the time-bias parameter into an indication value. The time-bias parameter represents a positive or negative value, and the conversion parameter is a positive value. A random access response message containing the indication value is sent to the satellite terminal. Satellite terminal 402 is configured to receive the extended PRACH access configuration information broadcast by the satellite base station; acquire its own positioning information and the ephemeris information of the satellite base station, and calculate the timing advance based on the positioning information and the ephemeris information; determine an extended random access preamble sequence from the set of extended random access preamble sequences, and send the extended random access preamble sequence to the satellite base station according to the timing advance; receive the random access response message containing the indication value sent by the satellite base station; restore the timing offset parameter based on the difference between the indication value and the conversion parameter determined according to the timing command adjustment coefficient, and adjust the timing advance based on the timing offset parameter.

[0090] Optionally, the satellite base station 401 is specifically used to perform time offset detection on the extended random access preamble sequence based on the number of repeating sequences indicated by the multi-sequence structure format and the length of a single sequence, to obtain time offset parameters.

[0091] Optionally, the satellite base station 401 is specifically used to determine a number of consecutive sequence truncation windows corresponding to the quantity; wherein the length of each sequence truncation window corresponds to the length of a single sequence; based on the number of consecutive sequence truncation windows, the extended random access preamble sequence is truncated to obtain the signals contained in each sequence truncation window; correlation detection is performed on the signals contained in each sequence truncation window to obtain the correlation detection result; and the time-biased parameter is determined based on the correlation detection result.

[0092] Optionally, the satellite base station 401 is specifically used to determine the validity of the signals contained in each sequence truncation window based on the correlation detection results; validity includes valid or invalid; determine the local time offset corresponding to the valid signal based on the correlation detection results corresponding to the valid signal, and determine the time offset parameter based on the local time offset and the position of the sequence truncation window corresponding to the invalid signal.

[0093] Optionally, the conversion parameters include default values ​​and correction parameters; the default values ​​are digitally correlated with the indicated values; the satellite base station 401 is specifically used to determine the correction parameters based on the angle between the beam direction of the satellite base station and the motion direction of the satellite base station and the timing command adjustment coefficient; the sum of the default values ​​and the correction parameters is determined as the conversion parameters.

[0094] Optionally, the satellite terminal 402 is specifically used to determine the new timing advance as the sum of the absolute value of the timing advance and the timing advance as the new timing advance if the timing offset parameter is positive; and to determine the new timing advance as the difference between the absolute value of the timing advance and the timing offset parameter if the timing offset parameter is negative.

[0095] like Figure 5 As shown, this application embodiment also provides an electronic device, including a processor 501, a memory 502, and a program or instructions stored in the memory 502 and executable on the processor 501. When the program or instructions are executed by the processor 501, they implement the various processes of the above-described method embodiment for adjusting the timing advance of the NTN access process and achieve the same technical effect. To avoid repetition, they will not be described again here.

[0096] This application also provides a readable storage medium storing a program or instructions. When the program or instructions are executed by a processor, they implement the various processes of the above-described method embodiment for adjusting the timing advance of the NTN access process, and achieve the same technical effect. To avoid repetition, they will not be described again here.

[0097] The processor is the processor in the electronic device described in the above embodiments. The readable storage medium includes computer-readable storage media, such as computer read-only memory (ROM), random access memory (RAM), magnetic disk, or optical disk.

[0098] It should be noted that, in this document, 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 a process, method, article, or apparatus. Without further limitations, 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. Furthermore, it should be noted that the scope of the methods and apparatuses in the embodiments of this application is not limited to performing functions in the order shown or discussed, but may also include performing functions substantially simultaneously or in the reverse order, depending on the functions involved. For example, the described methods may be performed in a different order than described, and various steps may be added, omitted, or combined. Additionally, features described with reference to certain examples may be combined in other examples.

[0099] Through the above description of the embodiments, those skilled in the art can clearly understand that the methods of the above embodiments can be implemented by means of software plus necessary general-purpose hardware platforms. Of course, they can also be implemented by hardware, but in many cases the former is a better implementation method. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, can be embodied in the form of a computer software product. This computer software product is stored in a storage medium (such as ROM / RAM, magnetic disk, optical disk) and includes several instructions to cause a terminal (which may be a mobile phone, computer, server, or network device, etc.) to execute the methods described in the various embodiments of this application.

[0100] The embodiments of this application have been described above with reference to the accompanying drawings. However, this application is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of this application without departing from the spirit and scope of the claims, and all of these forms are within the protection scope of this application.

[0101] The above description is merely a preferred embodiment and the technical principles employed in this application. This application is not limited to the specific embodiments described herein, and various obvious changes, readjustments, and substitutions that can be made by those skilled in the art will not depart from the scope of protection of this application. Therefore, although this application has been described in detail through the above embodiments, this application is not limited to the above embodiments, and may include more other equivalent embodiments without departing from the concept of this application, the scope of which is determined by the scope of the claims.

Claims

1. A method for adjusting timing advance during NTN access, applied to satellite base stations, characterized in that, The method includes: The extended PRACH access configuration information is broadcast within the coverage area of ​​the satellite base station. The extended PRACH access configuration information includes a set of extended random access preamble sequences and timing command adjustment coefficients. The extended random access preamble sequence is in a multi-sequence structure format, and the duration of the zero-correlation interval is longer than the duration of the cyclic prefix. If an extended random access preamble sequence is received from a satellite terminal based on the extended PRACH access configuration information, then the extended random access preamble sequence is subjected to time offset detection according to the detection method corresponding to the multi-sequence structure format to obtain a time offset parameter; the time offset parameter is the difference between the round-trip time and the pre-compensated timing advance; the round-trip time is the time it takes for the signal to travel between the satellite base station and the satellite terminal, and the pre-compensated timing advance is the advance of the uplink signal transmission time predetermined by the satellite terminal based on the ephemeris information broadcast by the satellite base station; The time offset parameter is summed with the conversion parameter determined according to the timing command adjustment coefficient to convert the time offset parameter into an indication value; wherein the time offset parameter represents a positive or negative value, and the conversion parameter is a positive value; A random access response message containing the indication value is sent to the satellite terminal so that the satellite terminal can restore the time offset parameter based on the difference between the indication value and the conversion parameter determined according to the timing command adjustment coefficient, and adjust the timing advance according to the restored time offset parameter.

2. The method according to claim 1, characterized in that, The step of performing time offset detection on the extended random access preamble sequence according to the detection method corresponding to the multi-sequence structure format to obtain time offset parameters includes: Based on the number of repeating sequences indicated by the multi-sequence structure format and the length of a single sequence, time offset detection is performed on the extended random access preamble sequence to obtain the time offset parameter.

3. The method according to claim 2, characterized in that, The step of performing time offset detection on the extended random access preamble sequence to obtain time offset parameters includes: Determine a plurality of consecutive sequence truncating windows corresponding to the quantity; wherein the length of each sequence truncating window corresponds to the length of the single sequence; Based on the aforementioned several consecutive sequence truncation windows, the extended random access preamble sequence is truncated to obtain the signals contained in each sequence truncation window. Correlation detection is performed on the signals contained in each sequence truncation window to obtain the correlation detection results; The time-biased parameter is determined based on the correlation detection results.

4. The method according to claim 3, characterized in that, Determining the time-off parameter based on the correlation detection result includes: The validity of the signals contained in each sequence truncation window is determined based on the correlation detection results; the validity includes whether the signal is valid or invalid. The local time offset corresponding to the valid signal is determined based on the correlation detection results corresponding to the valid signal, and the time offset parameter is determined based on the local time offset and the position of the sequence truncation window corresponding to the invalid signal.

5. The method according to claim 1, characterized in that, The conversion parameters include default values ​​and correction parameters; the default values ​​are associated with the digits of the indication values. The process of determining the conversion parameters includes: The correction parameter is determined based on the angle between the beam direction of the satellite base station and the motion direction of the satellite base station and the timing command adjustment coefficient; The sum of the default value and the correction parameter is determined as the conversion parameter.

6. A method for adjusting timing advance during NTN access, applied to a satellite terminal, characterized in that, The method includes: The system receives extended PRACH access configuration information broadcast by a satellite base station. The extended PRACH access configuration information includes a set of extended random access preamble sequences and timing command adjustment coefficients. The extended random access preamble sequences are in a multi-sequence structure format, and the duration of the zero-correlation interval is longer than the duration of the cyclic prefix. The system acquires the positioning information of the satellite terminal itself and the ephemeris information of the satellite base station, and calculates the timing advance based on the positioning information and the ephemeris information; the timing advance is the advance of the uplink signal transmission time. An extended random access preamble sequence is determined from the set of extended random access preamble sequences, and the extended random access preamble sequence is sent to the satellite base station according to the timing advance. The system receives a random access response message containing an indication value sent by the satellite base station. The indication value is obtained by the satellite base station by summing a time offset parameter with a conversion parameter determined according to the timing command adjustment coefficient. The time offset parameter is obtained by the satellite base station by performing time offset detection on the extended random access preamble sequence, and is the difference between the round-trip time and the timing advance. The round-trip time is the time it takes for the signal to travel between the satellite base station and the satellite terminal. The time offset parameter represents a positive or negative value, and the conversion parameter is a positive value. The time offset parameter is reconstructed based on the difference between the indicated value and the conversion parameter determined according to the timing command adjustment coefficient, and the timing advance is adjusted based on the time offset parameter.

7. The method according to claim 6, characterized in that, The adjustment of the timing advance based on the time offset parameter includes: If the time offset parameter is positive, then the sum of the timing advance and the absolute value of the time offset parameter is determined as the new timing advance. If the time offset parameter is negative, the difference between the timing advance and the absolute value of the time offset parameter is determined as the new timing advance.

8. A timing advance adjustment system for NTN access procedures, characterized in that, The system includes a satellite base station and a satellite terminal; The satellite base station is used to broadcast extended PRACH access configuration information within its coverage area. The extended PRACH access configuration information includes a set of extended random access preamble sequences and timing command adjustment coefficients. If an extended random access preamble sequence sent by the satellite terminal based on the extended PRACH access configuration information is received, the extended random access preamble sequence is subjected to time offset detection according to the detection method corresponding to the multi-sequence structure format to obtain a time offset parameter. The time offset parameter is the difference between the round-trip time and the pre-compensated timing advance. The round-trip time is the time it takes for the signal to travel between the satellite base station and the satellite terminal, and the pre-compensated timing advance is the advance of the uplink signal transmission time predetermined by the satellite terminal based on the ephemeris information broadcast by the satellite base station. The time offset parameter is summed with a conversion parameter determined according to the timing command adjustment coefficients to convert the time offset parameter into an indication value. The time offset parameter represents a positive or negative value, and the conversion parameter is a positive value. A random access response message containing the indication value is sent to the satellite terminal. The satellite terminal is configured to receive the extended PRACH access configuration information broadcast by the satellite base station; acquire its own positioning information and the ephemeris information of the satellite base station, and calculate the timing advance based on the positioning information and the ephemeris information; determine an extended random access preamble sequence from the set of extended random access preamble sequences, and send the extended random access preamble sequence to the satellite base station according to the timing advance; receive the random access response message containing the indication value sent by the satellite base station; restore the timing offset parameter based on the difference between the indication value and the conversion parameter determined according to the timing command adjustment coefficient, and adjust the timing advance based on the timing offset parameter.

9. An electronic device, characterized in that, It includes a processor, a memory, and a program or instructions stored in the memory and executable on the processor, wherein when the program or instructions are executed by the processor, they implement the timing advance adjustment method for the NTN access procedure as described in any one of claims 1-7.

10. A readable storage medium, characterized in that, The readable storage medium stores a program or instructions, which, when executed by a processor, implement the timing advance adjustment method for the NTN access process as described in any one of claims 1-7.

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