Up-link and down-link adaptive dynamic time synchronization method, system, device and medium

Abstract

The application discloses an uplink and downlink adaptive dynamic time synchronization method, system, device and medium, which captures the time change of a broadcast mark, dynamically adjusts the advance or lag of the terminal sending time point frame by frame, does not need to feed back adjustment parameters to the terminal, does not need multiple nodes to participate in calculation and adjustment, reduces the links of the synchronization adjustment process, improves the real-time performance of the time synchronization adjustment, improves the accuracy of the time delay adjustment, guarantees the time synchronization of the terminal sending signal and the payload sending signal, avoids communication abnormalities caused by signal crosstalk, can adapt to different carrier modes, different modulator processing delays, further improves the synchronization accuracy, and adapts to various communication scenes.

Description

Technical Field

[0001] This application relates to the field of satellite communication technology, and in particular to uplink and downlink adaptive dynamic time synchronization methods, systems, devices and media. Background Technology

[0002] Satellite communication utilizes artificial Earth satellites as relay stations to relay radio waves between two or more Earth stations. It is a form of space communication, functioning similarly to a relay station located high above the Earth. A fundamental characteristic of satellite communication is its ability to perform multiple access communication (i.e., multiple access connections). Among various multiple access methods, Time Division Multiple Access (TDMA) is widely used in medium- and high-capacity satellite lines due to its digital transmission methods and advantages such as no intermodulation, full utilization of power and bandwidth, and compatibility with both large and small stations. Examples include international satellite communication systems and the International Maritime Satellite Communication System. Because the payload and terminal use different clocks, and due to factors such as the high-speed movement of the payload and atmospheric effects, the distance between the terminal and the payload varies at different times, resulting in different signal arrival times. Therefore, the satellite TDMA communication mechanism has strict synchronization requirements for communication between the payload and the terminal, necessitating a precise and continuous clock synchronization mechanism. If the terminal and payload cannot achieve time synchronization, the signal from terminal A may "leak" into the time slot of terminal B, causing inter-symbol interference, and preventing normal communication between the payload and the terminal.

[0003] Existing solutions mainly fall into two categories. One involves a feedback mechanism where the terminal calculates the latency difference and then adjusts the latency of the terminal through the payload. The other involves the terminal station initiating a random access burst signal and requesting wireless resources. The master station needs to calculate the time value that the terminal station needs to adjust and transmit it to the terminal station. After parsing, the terminal station's FPGA unit fine-tunes the timestamp. Both solutions involve multiple nodes, which can affect real-time performance and latency adjustment accuracy. Summary of the Invention

[0004] This application aims to propose an uplink and downlink adaptive dynamic time synchronization method, system, device, and medium that can improve the real-time performance and accuracy of time synchronization adjustments.

[0005] In a first aspect, embodiments of this application provide an uplink / downlink adaptive dynamic time synchronization method, applied to a satellite communication system employing TDMA communication. The satellite communication system includes a payload and a terminal. At the beginning of each frame period, the payload sends a broadcast flag to the terminal. The uplink / downlink adaptive dynamic time synchronization method includes: The available time slots, the preset calculation and processing delay, the target transmission advance time length corresponding to the target carrier mode, the reference time corresponding to the first capture of the broadcast flag, the first time corresponding to the current capture of the broadcast flag, and the second time corresponding to the last capture of the broadcast flag are obtained. The target transmission advance time length represents the processing delay of the target carrier mode caused by the modulator. Based on the advance or lag of the relative frame period of the first time and the second time relative to the preset fixed frame period, and the start time of the uplink signal transmission of the previous frame period, the end time of the uplink signal transmission of the previous frame period and the start time of the uplink signal transmission of the current frame period are determined. The initial uplink signal transmission start time of the first frame period corresponding to the broadcast flag is first captured and determined based on the calculation processing delay, the target transmission advance time length, and the reference time. The modulator is activated based on the available time slot, the target carrier mode, the end time of the uplink signal transmission in the previous frame period, and the start time of the uplink signal transmission in the current frame period, so that the transmission signal transmission time of the terminal is synchronized with the transmission signal transmission time of the payload.

[0006] Secondly, embodiments of this application provide an uplink / downlink adaptive dynamic time synchronization system applied to a satellite communication system employing TDMA communication. The satellite communication system includes a payload and a terminal. At the beginning of each frame period, the payload sends a broadcast flag to the terminal. The uplink / downlink adaptive dynamic time synchronization system includes: The data acquisition unit is used to acquire available time slots, preset calculation and processing delay, target transmission advance time length corresponding to the target carrier mode, reference time corresponding to the first capture of the broadcast flag, first time corresponding to the current capture of the broadcast flag, and second time corresponding to the last capture of the broadcast flag. The target transmission advance time length characterizes the processing delay of the target carrier mode caused by the modulator. The dynamic delay adjustment unit is used to determine the end time of the uplink transmission signal of the previous frame period and the start time of the uplink transmission signal of the current frame period based on the advance or lag of the relative frame period of the first time and the second time relative to a preset fixed frame period, and the start time of the uplink transmission signal of the previous frame period. The initial uplink transmission signal start time of the first frame period corresponding to the broadcast flag is first captured and determined based on the calculation processing delay, the target transmission advance time length, and the reference time. The modulator transmission control unit is configured to activate the modulator based on the available time slot, the target carrier mode, the end time of the uplink transmission signal of the previous frame period, and the start time of the uplink transmission signal of the current frame period, so as to synchronize the transmission signal time of the terminal with the transmission signal time of the payload.

[0007] Thirdly, embodiments of this application provide an electronic device, which includes a processor and a memory storing computer program instructions; when the processor executes the computer program, it implements the uplink and downlink adaptive dynamic time synchronization method as described in the first aspect embodiment above.

[0008] Fourthly, embodiments of this application provide a computer-readable storage medium storing computer-executable instructions for performing the uplink / downlink adaptive dynamic time synchronization method as described in the first aspect of the embodiments above.

[0009] The uplink and downlink adaptive dynamic time synchronization method, system, device, and medium of this application capture the time changes of the broadcast flag and dynamically adjust the advance or lag of the terminal's transmission time frame by frame. This eliminates the need for the payload to feed back adjustment parameters to the terminal and for multiple nodes to participate in the calculation and adjustment, reducing the steps in the synchronization adjustment process. This improves both the real-time performance of time synchronization adjustment and the accuracy of delay adjustment, ensuring time synchronization between the terminal's transmitted signal and the payload's transmitted signal, avoiding communication anomalies caused by signal crosstalk, and adapting to different modulator processing delays under different carrier modes, further improving the accuracy of synchronization and adapting to various communication scenarios.

[0010] Other features and advantages of this application will be set forth in the following description and will be apparent in part from the description or may be learned by practicing the application. Attached Figure Description

[0011] The above and / or additional aspects and advantages of this application will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which: Figure 1 This is a timing diagram of the uplink and downlink frames of the service beam in an embodiment of this application; Figure 2 This is a diagram of the uplink frame structure of a service beam according to an embodiment of this application; Figure 3 This is a flowchart of an embodiment of the uplink and downlink adaptive dynamic time synchronization method of this application; Figure 4 This is a schematic diagram of dynamic delay adjustment according to an embodiment of this application; Figure 5 This is a schematic diagram of dynamic delay adjustment when no capture flag is received during an embodiment of this application; Figure 6 This is a system block diagram of an uplink and downlink adaptive dynamic time synchronization system according to an embodiment of this application.

[0012] Figure label: Payload 100, payload transmitting unit 110, payload receiving unit 120; Terminal 200, channel configuration storage unit 210, prior information storage unit 220, demodulator 230, uplink and downlink adaptive dynamic time synchronization system 240, time slot analysis unit 241, carrier mode analysis unit 242, dynamic delay adjustment unit 243, modulator transmission and control unit 244, anomaly protection unit 245, modulator 250. Detailed Implementation

[0013] The embodiments of this application are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this application, and should not be construed as limiting this application.

[0014] In the description of this application, the use of terms such as "first," "second," etc., is for the purpose of distinguishing technical features only and should not be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated or the order of the technical features indicated.

[0015] In the description of this application, it should be understood that the orientation descriptions, such as up, down, etc., are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0016] In the description of this application, it should be noted that, unless otherwise explicitly defined, terms such as "setup," "installation," and "connection" should be interpreted broadly, and those skilled in the art can reasonably determine the specific meaning of the above terms in this application in conjunction with the specific content of the technical solution.

[0017] To better understand the uplink and downlink adaptive dynamic time synchronization method in the embodiments of this application, the TDMA technology will first be explained.

[0018] TDMA communication involves dividing a physical communication channel (frequency band) into a series of periodically repeating, non-overlapping time slots on the time axis, and allocating these time slots to different users as needed. Each user can only send or receive data in their assigned time slot, and remains silent in other time slots.

[0019] Satellite TDMA (Time-to-DMA) communication is a highly efficient and flexible multiple access method widely used in satellite communications. It can be used to coordinate communication between multiple ground stations and a satellite, and is particularly suitable for multi-point-to-multi-point data exchange and on-board switching. In satellite TDMA, multiple ground stations (terminals 200) share the full bandwidth of the same satellite transponder (payload 100), but they transmit signals in different, strictly planned time slots. The satellite acts as an "airborne relay station" or "switchboard" in orbit.

[0020] Because payload 100 and terminal 200 use different clocks, and due to the high-speed movement of payload 100 and atmospheric effects, the distance between terminal 200 and payload 100 varies at different times, resulting in different signal arrival times. Therefore, the satellite TDMA communication mechanism has strict synchronization requirements for communication between payload 100 and terminal 200, necessitating a precise and continuous clock synchronization mechanism. If terminal 200 and payload 100 cannot achieve time synchronization, the signal from terminal A may "leak" into the time slot of terminal B, causing inter-symbol interference. Therefore, time synchronization technology must be introduced to ensure that all signals are aligned with the time slot boundaries at payload 100.

[0021] Time synchronization technology is considered the lifeline of satellite TDMA communication and is the most critical and complex part of satellite TDMA. All terminal 200 users must be strictly synchronized with a common reference clock (payload clock); the payload 100 side acts as the "master clock" and is responsible for sending synchronization signals; the terminal 200 side must continuously adjust its own clock to ensure that it starts transmitting or receiving data at the precise moment.

[0022] like Figure 1 As shown, Figure 1 This is a timing diagram of the uplink and downlink frames of the service beam in an embodiment of this application. When the system operates in satellite timing mode, the uplink and downlink frames of the communication payload service beam are time-aligned. The uplink frame is the frame sent from terminal 200 to payload 100, and the downlink frame is the frame sent from payload 100 to terminal 200. The start of the satellite second pulse is aligned with the start of the uplink frame.

[0023] like Figure 2 As shown, Figure 2 This is a diagram of the uplink frame structure of a service beam according to an embodiment of this application. The uplink and downlink frame periods of the service beam are... ,Depend on It consists of 1 time slot, each time slot having a length of 1. The time slot numbers are from 1 to .

[0024] For different carrier rates, the number of time slots occupied by each uplink burst transmitted by terminal 200 is as follows: (1) Carrier mode 1: 1 time slot resource (continuously occupied) ); (2) Carrier mode 2: 2 time slot resources (continuously occupied) ); (3) Carrier mode 3: Time slot resources (continuously occupied) ).

[0025] When the system operates in TDMA timing mode, the uplink and downlink frames of the communication payload service beam are aligned in time and in sequence number, without constraining the timing relationship between the start of the satellite second pulse and the start of the uplink frame.

[0026] The technical solution of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described below are some embodiments of this application, not all embodiments.

[0027] See Figure 3 , Figure 3 This is a flowchart of an embodiment of the uplink / downlink adaptive dynamic time synchronization method provided in this application. This method is applied to a satellite communication system employing TDMA communication. The satellite communication system includes a payload 100 and a terminal 200. At the beginning of each frame period, the payload 100 sends a broadcast flag to the terminal 200. The uplink / downlink adaptive dynamic time synchronization method includes, but is not limited to, steps S110 to S130: Step S110: Obtain available time slots, preset calculation processing delay, target transmission advance time length corresponding to the target carrier mode, reference time corresponding to the first capture of the broadcast flag, first time corresponding to the current capture of the broadcast flag and second time corresponding to the last capture of the broadcast flag. The target transmission advance time length represents the processing delay of the target carrier mode caused by the modulator 250. Step S120: Based on the advance or lag of the relative frame period of the first time and the second time relative to the preset fixed frame period, and the start time of the uplink signal transmission of the previous frame period, determine the end time of the uplink signal transmission of the previous frame period and the start time of the uplink signal transmission of the current frame period. The initial uplink signal transmission start time of the first frame period corresponding to the first capture of the broadcast flag is determined based on the calculation processing delay, the target transmission advance time length, and the reference time. Step S130: The modulator 250 is turned on according to the available time slot, the target carrier mode, the end time of the uplink signal transmission in the previous frame period and the start time of the uplink signal transmission in the current frame period, so that the transmission signal time of the terminal 200 is synchronized with the transmission signal time of the payload 100.

[0028] In this embodiment, by capturing the time change of the broadcast flag, the advance or lag of the transmission time of the terminal 200 is dynamically adjusted frame by frame. This eliminates the need for the payload 100 to feed back adjustment parameters to the terminal 200, and also eliminates the need for multiple nodes to participate in the calculation and adjustment. This reduces the steps in the synchronization adjustment process, improving both the real-time performance of the time synchronization adjustment and the accuracy of the delay adjustment. It ensures that the signal transmitted by the terminal 200 is synchronized with the signal transmitted by the payload 100, avoiding communication anomalies caused by signal crosstalk. At the same time, it can adapt to different carrier modes and different processing delays of the modulator 250, further improving the accuracy of synchronization and adapting to various communication scenarios.

[0029] In step S110, the available time slots are obtained through steps S111 to S113: Step S111: Obtain the time slot parameters and target carrier mode parameters in the channel configuration, as well as the time slot length parameters occupied by different carrier modes in the prior information. Step S112: Determine the target time slot length parameter occupied by the target carrier mode based on the carrier mode parameters of the target carrier mode and the time slot length parameters occupied by different carrier modes; Step S113: Determine the available time slots based on the target time slot length parameter.

[0030] In FPGA implementation, the time slot parameter is a number with a bit width of Mbit, representing the time within one frame period. Whether a time slot is open or not, the corresponding bit is set to 0 to indicate that the current time slot is occupied, and set to 1 to indicate that the current time slot is available; the carrier mode parameter indicates that the current modulator 250 needs to use a certain rate to send signals, and different carrier modes use different carrier modes to send signals.

[0031] As can be seen from the above, carrier modes 1, 2, and 3 occupy positions 1, 2, and 3 respectively. Therefore, based on the carrier mode configured in the channel configuration and the carrier mode information in the prior information, the carrier mode used to transmit the signal can be determined. When carrier mode 1 is used, the available time slots are the time slots with the corresponding bits of the channel configuration time slot parameters set to 1; when carrier mode 2 is used, the available time slots within a frame period need to be determined. Each time slot is analyzed, and the availability of two consecutive time slots is determined to identify available time slots. If three time slots are available, either the first two time slots or the last two time slots are considered available. When using carrier mode 3, the time slots within a frame period need to be analyzed. Analyze each time slot to detect continuous The availability of time slots is determined by the number of available time slots, such as when more than [number] time slots are encountered. Less than If all time slots are continuously available, then it can be determined that among them... A continuous time slot is a usable time slot.

[0032] The aforementioned preset computational processing delay refers to the processing delay of implementing the uplink and downlink adaptive dynamic time synchronization method in this application embodiment, i.e., the time consumed by hardware computation.

[0033] The aforementioned target transmission advance time characterizes the processing delay of the target carrier mode caused by the modulator 250.

[0034] In step S120, the initial uplink signal transmission start time is obtained through the following steps: The fixed processing delay is obtained by summing the calculated processing delay and the target transmission advance time. Adding a fixed processing delay to the reference time yields the initial uplink signal transmission start time.

[0035] In some implementations, step S120 includes, but is not limited to, steps S121 to S123: Step S121: If the relative frame period between the first time and the second time is earlier than the preset fixed frame period, subtract the second time from the first time to obtain the length of the first relative frame period. Step S122: Add the first relative frame period length to the start time of the uplink signal transmission in the previous frame period to obtain the first target time; Step S123: The first target time is determined as the end time of uplink signal transmission in the previous frame period and the start time of uplink signal transmission in the current frame period.

[0036] In some implementations, step S120 includes, but is not limited to, steps S124 to S127: Step S124: If the relative frame period between the first time and the second time lags behind the preset fixed frame period, subtract the second time from the first time to obtain the second relative frame period length. Step S125: Add the preset fixed frame period length to the start time of uplink signal transmission in the previous frame period to obtain the end time of uplink signal transmission in the previous frame period. Step S126: Add the second relative frame period length to the start time of transmitting the uplink signal in the previous frame period to obtain the second target time; Step S127: Determine the second target time as the start time of transmitting the uplink signal in the current frame period.

[0037] refer to Figure 4 , Figure 4 This is a schematic diagram of dynamic delay adjustment according to an embodiment of this application. The following is a detailed description of step S120 using a specific embodiment.

[0038] Assuming that a broadcast flag is received near the beginning of each frame period, by assuming different broadcast flag times, the uplink and downlink time deviations in the actual environment are simulated, a dynamic delay adjustment scheme is given, and then the start and end times of the modulator's 250 modulation signals are determined.

[0039] The modulation signal processing delay is inconsistent for different carrier modes, so the transmission advance time length is inconsistent. However, once the carrier mode is determined, the transmission advance time length is a fixed value. In addition, the processing delay of the uplink and downlink adaptive dynamic time synchronization method in this application embodiment (i.e., the preset calculation processing delay) is also a fixed value. Therefore, the sum of the delay of the target transmission advance time length and the preset calculation processing delay (fixed processing delay) is also a fixed value.

[0040] Figure 4 The first horizontal line at the top mainly represents the relationship between the demodulator 230 capturing the broadcast flag and the frame period, and the red vertical line with the arrow indicates the moment of each capture of the broadcast flag. Figure 4 , Figure 5 The blue vertical line is abbreviated as "capture flag" (or "capture flag"). The other blue vertical lines indicate the end of the current absolute frame period (i.e., the preset fixed frame period) and the start of the next absolute frame period. The second horizontal line below mainly indicates the relationship between the start time of uplink signal transmission, the end time of uplink signal transmission, and the frame period of modulator 250. The green vertical solid line with an arrow below indicates the start time of uplink signal transmission by modulator 250 (…). Figure 4 , Figure 5 The abbreviation is "start of transmission" (or "start of transmission"). The yellow dashed line with an arrow above it indicates the end time of the uplink signal transmission of the corresponding modulator 250. Figure 4 , Figure 5 The blue vertical line is abbreviated as "end of frame" (or "end of frame"). The other blue vertical lines indicate the end of the current absolute frame period and the start of the next absolute frame period.

[0041] The start time of uplink signal transmission for each modulator 250 corresponds to an end time of uplink signal transmission. The time length between the start and end times of uplink signal transmission is a relative frame period. Due to the relative advance and lag of the acquisition flag, the length of the relative frame period may be less than, greater than, or equal to the length of the absolute frame period. (Right now Figure 4 The interval between two adjacent blue vertical lines (the distance between them). The difference between the start positions of the frame period of the first and second horizontal lines is the fixed processing delay. T (i.e.) Figure 4 The horizontal spacing between the first blue vertical line in the first horizontal line and the first blue vertical line in the second horizontal line.

[0042] Figure 4 middle, This represents the length of a fixed frame period. The position indicates the moment when the demodulator 230 captures the first broadcast flag, i.e., the reference time; This indicates that the second broadcast flag starts earlier than the second fixed frame period. The length of time; This indicates that the third broadcast flag has started earlier than the third fixed frame period. The length of time, < ; This indicates that the fourth broadcast flag begins to lag behind the fourth fixed frame period. The length of time; This indicates that the fifth broadcast flag has started to lag behind the fifth fixed frame period. The length of time, > ; This indicates that the sixth broadcast flag begins to lag behind the sixth fixed frame period. The length of time, < .

[0043] The dynamic delay adjustment process is a relative delay adjustment process. Each adjustment is based on the previous adjustment's uplink signal start time, using the relative advance or lag time between the two acquisitions of the broadcast flag as the adjustment amount. The following details the partial uplink signal start and end times.

[0044] Figure 4 The first capture broadcast flag on the first horizontal line is considered a reference moment for starting adjustments. The relative frame period of the second capture broadcast flag begins (i.e., the first moment when the second capture broadcast flag is displayed, denoted as...). It was brought forward. The duration of the transmission is such that the start time of the first uplink signal transmission on the second horizontal line is the reference time plus a fixed processing delay, i.e. At this point, the start time of uplink signal transmission is aligned with the frame period time, and the end time of uplink signal transmission is relatively advanced. The length of time, then the amount of delay adjustment this time is The first uplink signal transmission ended at [time]. At time 1, the relative frame period length between the start time of the first uplink signal transmission and the end time of the first uplink signal transmission is 1. Less than .

[0045] Figure 4In the middle, because the second capture broadcast mark on the first horizontal line is earlier than the first capture broadcast mark. The duration is such that the start time of the second uplink signal transmission on the second horizontal line is equal to the end time of the first uplink signal transmission. The timing of the second uplink signal transmission ends depends on the amount of time the third capture broadcast flag on the first horizontal line precedes or lags the second capture broadcast flag. Figure 4 It can be known < Therefore, the third capture broadcast flag lags behind the second capture broadcast flag by a delay of [time value missing]. Therefore, the time length between the start and end times of the second uplink signal transmission on the second horizontal line is equal to the preset fixed frame period length T. The start time of the third uplink signal transmission is the sum of the start time of the second uplink signal transmission and the time length between the third capture broadcast flag and the second capture broadcast flag. ,in, The time of the third capture broadcast flag and the time of the second capture broadcast flag are determined here. This is for illustrative purposes only.

[0046] However, Figure 4 The sixth capture broadcast flag on the first horizontal line is delayed relative to the start of the sixth fixed frame period. The length of time, but due to < The sixth capture broadcast flag is earlier than the fifth capture broadcast flag. The specific advance is related to the previous delays. Therefore, the time length between the start and end times of the fifth uplink signal transmission (as shown in the second horizontal line) is less than one fixed frame period. The start time of the sixth uplink signal transmission is the end time of the fifth uplink signal transmission.

[0047] The calculations for the start and end times of subsequent uplink signal transmissions can be derived based on the above reasoning principles, and will not be described in detail here.

[0048] In some implementations, the uplink and downlink adaptive dynamic time synchronization method further includes: if a broadcast flag is not captured after a first preset time period, determining the start time and end time of uplink signal transmission for the current frame period according to the length of a preset fixed frame period.

[0049] In practical use, the demodulator 230 of terminal 200 may be affected by various factors during the acquisition process, resulting in a situation where it can initially capture the broadcast flag normally, but fails to capture it for a certain period of time. This application addresses this by determining the start and end times of uplink signal transmission for the current frame period according to the length of a preset fixed frame period when the broadcast flag is not captured for more than a first preset time. This follows the "frame number locking" and "open-loop hold" mechanism, prioritizing service continuity rather than immediately silencing upon loss of lock. Terminal 200 maintains a local frame counter, which accumulates independently and is calibrated once a valid broadcast frame is received. Even if several frames are not broadcast, as long as the local counter is not reset, the timing reference of terminal 200 remains valid, and uplink signals can still be transmitted normally. Broadcast loss does not equate to uplink synchronization failure; it may only be an occasional obstruction or interference in the downlink, but the uplink from terminal 200 to payload 100 is usually normal. If terminal 200 immediately stops transmitting simply because it did not receive a broadcast, it will be considered to have created an uplink burst interference and interrupt ongoing real-time services (such as voice), which is unacceptable for the communication system.

[0050] refer to Figure 5 , Figure 5 This is a schematic diagram illustrating dynamic delay adjustment when a capture flag is not received during an embodiment of this application. The first three captures are normal, but the flag is not captured on the fourth attempt. Therefore, the interval between the start time of the fourth uplink signal transmission and the start time of the third uplink signal transmission is equal to the length of a preset fixed frame period. The interval between the end of the fourth uplink signal transmission and the start of the fourth uplink signal transmission is also equal to the length of the preset fixed frame period. Furthermore, the start time of the fifth uplink signal transmission coincides with the end time of the fourth uplink signal transmission, and so on.

[0051] In some implementations, the uplink and downlink adaptive dynamic time synchronization method further includes: if a broadcast flag is not captured after a second preset time period, re-establishing the communication process between payload 100 and terminal 200 to re-acquire the reference time. The second preset time period is longer than the first preset time period. If a broadcast flag is not captured after the second preset time period, the communication process between payload 100 and terminal 200 needs to be re-established to re-acquire the reference time and re-perform uplink and downlink time synchronization. This ensures that the time synchronization mechanism will not become unrecoverable due to prolonged loss of lock, thus improving the robustness and reliability of the synchronization mechanism. The second preset time period is longer than the first preset time period because a single or few instances of not capturing the broadcast flag are only temporary anomalies. If there is only a short period of packet loss, resynchronization is not necessary. However, a prolonged period of not capturing the broadcast flag indicates a serious synchronization deviation or link interruption. In this case, communication needs to be re-established to acquire the reference clock in order to restore normal synchronization and avoid the continuous accumulation of erroneous delay adjustments leading to a complete communication interruption.

[0052] It should be noted that the specific values ​​of the first and second preset durations can be adjusted according to the actual situation, and no specific limit is made here.

[0053] In some implementations, step S130 includes, but is not limited to, steps S131 to S133: Step S131: Determine the number of physical layer burst frames, the number of coding blocks, the coding block activation time slot, the activation count, and the activation interval based on the available time slots and the target carrier mode; Step S132: Generate a transmission end indication signal based on the number of physical layer burst frames, the number of coding blocks, the coding block effective time slot, the number of effective times and the effective interval, as well as the end time of the transmission uplink signal of the previous frame period, and send the transmission end indication signal to the modulator 250 so that the modulator 250 ends the signal transmission of the previous frame period. Step S133: Generate a transmission start indication signal based on the number of physical layer burst frames, the number of coding blocks, the coding block effective time slot, the number of effective times and the effective interval, as well as the start time of the transmission uplink signal in the current frame period, and send the transmission start indication signal to the modulator 250 so that the modulator 250 starts the signal transmission of the current frame period.

[0054] It should be noted that the working principle of the modulator 250 is existing technology known to those skilled in the art, and will not be described in detail here.

[0055] Please see Figure 6 , Figure 6This is a system block diagram of an uplink / downlink adaptive dynamic time synchronization system 240 according to an embodiment of this application. The uplink / downlink adaptive dynamic time synchronization system 240 of this embodiment is applied to a satellite communication system employing TDMA communication. The satellite communication system includes a payload 100 and a terminal 200. The payload 100 sends a broadcast flag to the terminal 200 at the beginning of each frame period. The uplink / downlink adaptive dynamic time synchronization system 240 includes a data acquisition unit, a dynamic delay adjustment unit 243, and a modulator transmission and control unit 244.

[0056] The data acquisition unit is used to acquire available time slots, preset calculation and processing delay, target transmission advance time length corresponding to the target carrier mode, reference time corresponding to the first capture of the broadcast flag, first time corresponding to the current capture of the broadcast flag and second time corresponding to the last capture of the broadcast flag. The target transmission advance time length characterizes the processing delay of the target carrier mode caused by the modulator 250. The dynamic delay adjustment unit 243 is used to determine the end time of the uplink transmission signal of the previous frame period and the start time of the uplink transmission signal of the current frame period based on the advance or lag of the relative frame period of the first time and the second time relative to the preset fixed frame period, and the start time of the uplink transmission signal of the previous frame period. The initial uplink transmission signal start time of the first frame period corresponding to the first capture of the broadcast flag is determined based on the calculation processing delay, the target transmission advance time length and the reference time. The modulator control unit 244 is used to activate the modulator 250 according to the available time slot, the target carrier mode, the end time of the uplink signal transmission in the previous frame period and the start time of the uplink signal transmission in the current frame period, so as to synchronize the transmission signal transmission time of the terminal 200 with the transmission signal transmission time of the payload 100.

[0057] The payload 100 includes a payload transmitting unit 110 and a payload receiving unit 120. In this embodiment, the payload transmitting unit 110 is used to transmit broadcast information to the demodulator 230 of the terminal 200 so that the demodulator 230 can capture the broadcast flag; the payload receiving unit 120 is used to receive the signal modulated by the modulator 250 of the terminal 200.

[0058] Terminal 200 includes a channel configuration storage unit 210, a priori information storage unit 220, a demodulator 230, an uplink / downlink adaptive dynamic time synchronization system 240 according to this embodiment, and a modulator 250. The channel configuration storage unit 210 stores time slot parameters and carrier mode parameters of the target carrier mode, while the priori information storage unit 220 stores time slot length parameters occupied by different carrier modes. The demodulator 230 captures the broadcast flag in the broadcast information transmitted by the payload transmission unit 110. The modulator 250, in response to the transmission start indication signal and transmission end indication signal obtained from the uplink / downlink adaptive dynamic time synchronization system 240 according to this embodiment, transmits a signal to the payload receiving unit 120.

[0059] The uplink / downlink adaptive dynamic time synchronization system 240 includes a data acquisition unit, a dynamic delay adjustment unit 243, and a modulator transmission control unit 244. The data acquisition unit includes, but is not limited to, a time slot analysis unit 241 and a carrier mode analysis unit 242. The time slot analysis unit 241 acquires time slot parameters, carrier mode parameters of the target carrier mode, and time slot length parameters occupied by different carrier modes, and analyzes the available time slots. The carrier mode analysis unit 242 determines the target carrier mode and the corresponding target transmission advance time length. It should be noted that the modulator transmission control unit 244 represents the modulator transmission uplink signal control unit.

[0060] It should be noted that the basic architecture of satellite communication systems is existing technology known to those skilled in the art, and will not be described in detail here.

[0061] In some embodiments, the uplink and downlink adaptive dynamic time synchronization system 240 of this application further includes an anomaly protection unit 245, which is used to determine the start time and end time of uplink signal transmission in the current frame period according to the length of the relative frame period of the previous frame period when a broadcast flag is not captured for a first preset time period, and to re-establish the communication process between the payload 100 and the terminal 200 to re-acquire the reference time when a broadcast flag is not captured for a second preset time period, wherein the second preset time period is longer than the first preset time period.

[0062] Since the uplink and downlink adaptive dynamic time synchronization system of this application adopts all the technical solutions of the uplink and downlink adaptive dynamic time synchronization method of this application, it also has all the technical effects of the uplink and downlink adaptive dynamic time synchronization method, which will not be repeated here.

[0063] The uplink and downlink adaptive dynamic time synchronization system in this application embodiment can be an electronic device or a component within an electronic device, such as an integrated circuit or a chip. The electronic device can be a terminal or other devices besides a terminal. For example, the electronic device can be a mobile phone, tablet computer, laptop computer, PDA, in-vehicle electronic device, mobile internet device (MID), augmented reality (AR) / virtual reality (VR) device, robot, wearable device, ultra-mobile perSonal computer (UMPC), netbook, or perSonal digital assistant (PDA), etc. It can also be a server, network attached storage (NAS), perSonal computer (PC), television, ATM, or self-service machine, etc. This application embodiment does not specifically limit the specific implementation.

[0064] This application also provides an electronic device, including a processor and a memory. The memory stores a program or instructions that can run on the processor. When the program or instructions are executed by the processor, they implement the various steps of the above-described uplink and downlink adaptive dynamic time synchronization method embodiments and achieve the same technical effect. To avoid repetition, they will not be described again here.

[0065] 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 uplink and downlink adaptive dynamic time synchronization method embodiments and achieve the same technical effect. To avoid repetition, they will not be described again here.

[0066] It should be clarified that this application is not limited to the specific configurations and processes described above. For the sake of brevity, detailed descriptions of known methods are omitted here. In the above embodiments, several specific steps are described and illustrated as examples. However, the method process of this application is not limited to the specific steps described and illustrated. Those skilled in the art can make various changes, modifications, and additions, or change the order of steps, after understanding the spirit of this application.

[0067] The functional blocks described above can be implemented as hardware, software, firmware, or a combination thereof. When implemented in hardware, they can be, for example, electronic circuits, application-specific integrated circuits (ASICs), appropriate firmware, plug-ins, function cards, etc. When implemented in software, the elements of this application are programs or code segments used to perform the required tasks. The programs or code segments can be stored on a machine-readable medium or transmitted over a transmission medium or communication link via data signals carried on a carrier wave. "Machine-readable medium" can include any medium capable of storing or transmitting information. Examples of machine-readable media include electronic circuits, semiconductor memory devices, ROM, flash memory, erasable ROM (EROM), floppy disks, CD-ROMs, optical disks, hard disks, fiber optic media, radio frequency (RF) links, etc. Code segments can be downloaded via computer networks such as the Internet, intranets, etc.

[0068] It should also be noted that the exemplary embodiments mentioned in this application describe methods or systems based on a series of steps or apparatus. However, this application is not limited to the order of the above steps; that is, the steps can be performed in the order mentioned in the embodiments, or in a different order, or several steps can be performed simultaneously.

[0069] The above are merely specific embodiments of this application. Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working processes of the systems, modules, and units described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here. It should be understood that the protection scope of this application is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in this application, and these modifications or substitutions should all be covered within the protection scope of this application.

Claims

1. A method for uplink and downlink adaptive dynamic time synchronization, characterized in that, This is applied to a satellite communication system employing TDMA communication, the satellite communication system comprising a payload and a terminal, wherein the payload sends a broadcast flag to the terminal at the beginning of each frame period; The uplink and downlink adaptive dynamic time synchronization method includes: The available time slots, the preset calculation and processing delay, the target transmission advance time length corresponding to the target carrier mode, the reference time corresponding to the first capture of the broadcast flag, the first time corresponding to the current capture of the broadcast flag, and the second time corresponding to the last capture of the broadcast flag are obtained. The target transmission advance time length represents the processing delay of the target carrier mode caused by the modulator. Based on the relative frame period of the first time and the second time relative to a preset fixed frame period, the advance or lag amount, and the start time of the uplink signal transmission in the previous frame period, the end time of the uplink signal transmission in the previous frame period and the start time of the uplink signal transmission in the current frame period are determined. Specifically, the initial start time of the uplink signal transmission in the first frame period corresponding to the first captured broadcast flag is determined based on the calculation processing delay, the target transmission advance time length, and the reference time. If the broadcast flag is not captured within a first preset time, the start time and end time of the uplink signal transmission in the current frame period are determined according to the length of the preset fixed frame period. If the broadcast flag is not captured within a second preset time, the communication process between the payload and the terminal is re-established to reacquire the reference time, where the second preset time is longer than the first preset time. The modulator is activated based on the available time slot, the target carrier mode, the end time of the uplink signal transmission in the previous frame period, and the start time of the uplink signal transmission in the current frame period, so that the transmission signal transmission time of the terminal is synchronized with the transmission signal transmission time of the payload.

2. The uplink and downlink adaptive dynamic time synchronization method according to claim 1, characterized in that, The initial uplink signal transmission start time is obtained through the following steps: The fixed processing delay is obtained by summing the calculated processing delay and the target transmission advance time. The fixed processing delay is added to the reference time to obtain the initial transmission start time of the uplink signal.

3. The uplink and downlink adaptive dynamic time synchronization method according to claim 1, characterized in that, The step of determining the end time of uplink transmission in the previous frame period and the start time of uplink transmission in the current frame period based on the advance or lag of the relative frame period of the first time and the second time relative to a preset fixed frame period, and the start time of uplink transmission in the previous frame period, includes: If the relative frame period between the first time and the second time is earlier than the preset fixed frame period, the first time is subtracted from the second time to obtain the length of the first relative frame period. The first target time is obtained by adding the start time of the uplink signal transmission in the previous frame period to the length of the first relative frame period. The first target time is determined as the end time of uplink signal transmission in the previous frame period and the start time of uplink signal transmission in the current frame period.

4. The uplink and downlink adaptive dynamic time synchronization method according to claim 3, characterized in that, The step of determining the end time of uplink transmission in the previous frame period and the start time of uplink transmission in the current frame period based on the advance or lag of the relative frame period of the first time and the second time relative to a preset fixed frame period, and the start time of uplink transmission in the previous frame period, further includes: If the relative frame period between the first time and the second time lags behind the preset fixed frame period, the second time is subtracted from the first time to obtain the second relative frame period length. Add the preset fixed frame period length to the start time of uplink signal transmission in the previous frame period to obtain the end time of uplink signal transmission in the previous frame period. The second target time is obtained by adding the start time of the uplink signal transmission in the previous frame period to the second relative frame period length. The second target time is determined as the start time of transmitting the uplink signal in the current frame period.

5. The uplink and downlink adaptive dynamic time synchronization method according to claim 1, characterized in that, The available time slots are obtained through the following steps: Obtain the time slot parameters and target carrier mode parameters from the channel configuration, as well as the time slot length parameters occupied by different carrier modes from the prior information; Based on the carrier mode parameters of the target carrier mode and the time slot length parameters occupied by different carrier modes, determine the target time slot length parameters occupied by the target carrier mode; The available time slots are determined based on the target time slot length parameter.

6. An uplink and downlink adaptive dynamic time synchronization system, characterized in that, This is applied to a satellite communication system employing TDMA communication, the satellite communication system comprising a payload and a terminal, wherein the payload sends a broadcast flag to the terminal at the beginning of each frame period; The uplink and downlink adaptive dynamic time synchronization system includes: The data acquisition unit is used to acquire available time slots, preset calculation and processing delay, target transmission advance time length corresponding to the target carrier mode, reference time corresponding to the first capture of the broadcast flag, first time corresponding to the current capture of the broadcast flag, and second time corresponding to the last capture of the broadcast flag. The target transmission advance time length characterizes the processing delay of the target carrier mode caused by the modulator. The dynamic delay adjustment unit is used to determine the end time of the uplink signal transmission in the previous frame period and the start time of the uplink signal transmission in the current frame period based on the advance or lag of the relative frame period of the first time and the second time relative to a preset fixed frame period, and the start time of the uplink signal transmission in the previous frame period. Specifically, the initial start time of the uplink signal transmission in the first frame period corresponding to the broadcast flag is determined based on the calculation processing delay, the target transmission advance time length, and the reference time. If the broadcast flag is not captured within a first preset time, the start time and end time of the uplink signal transmission in the current frame period are determined according to the length of the preset fixed frame period. If the broadcast flag is not captured within a second preset time, the communication process between the payload and the terminal is re-established to re-acquire the reference time, where the second preset time is longer than the first preset time. The modulator transmission control unit is configured to activate the modulator based on the available time slot, the target carrier mode, the end time of the uplink transmission signal of the previous frame period, and the start time of the uplink transmission signal of the current frame period, so as to synchronize the transmission signal time of the terminal with the transmission signal time of the payload.

7. An electronic device, characterized in that, The electronic device includes a processor and a memory storing computer program instructions; when the processor executes the computer program, it implements the uplink and downlink adaptive dynamic time synchronization method as described in any one of claims 1 to 5.

8. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores computer-executable instructions for causing a computer to perform the uplink / downlink adaptive dynamic time synchronization method as described in any one of claims 1 to 5.

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