Adaptive Transmission Method for Terminal Data of Low-Earth Orbit Satellite Overhead Window and Baseline Link

Abstract

This invention discloses a terminal data adaptive transmission method using a low-Earth orbit (LEO) satellite overpass window and a backup link, comprising: classifying data into high and low time-sensitivity categories and defining remaining time margins; predicting the overpass window to obtain the remaining window duration; configuring the LEO satellite link as the primary link and BeiDou short message service as the backup link; transmitting high-time-sensitivity data in real time via the LEO satellite link, and transmitting a summary via the backup link when outside the window or when the link is unavailable, and retransmitting complete data and associated images after the window recovers; transmitting low-time-sensitivity data only within the window, otherwise buffering and sorting according to scheduling priority; if new high-time-sensitivity data is generated while transmitting low-time-sensitivity data within the window, immediately interrupting and saving the breakpoint, and prioritizing the transmission of high-time-sensitivity data; stopping new tasks when the remaining window duration is less than the soft landing threshold; hibernating outside the window and waking up in advance before the window. This invention prioritizes real-time alarm transmission under limited window resources, supports image fragmentation and continuation, and low-power operation, and is suitable for power transmission line icing monitoring.

Description

Technical Field

[0001] This application relates to the fields of power system disaster monitoring and satellite communication technology, specifically to a terminal data adaptive transmission method for low-orbit satellite overpass window and backup link. Background Technology

[0002] Icing on transmission lines is one of the major hazards threatening the safe operation of the power grid. Online icing monitoring terminals typically need to collect two types of data. The first type is structured status data, including icing thickness, icing growth rate, conductor temperature, ambient temperature and humidity, equipment power supply status, and terminal self-test status. The second type is image data, including icing images, keyframe images, and compressed image packets. The first type of data is small in volume but requires reporting within seconds to quickly detect hazards. The second type of data is larger in volume and is mainly used for manual verification and detailed disaster analysis, allowing for delays of minutes or even longer. In remote mountainous areas, high-altitude heavy icing areas, and unattended areas, public network signals are often missing or extremely unstable. Existing technologies mainly rely on a single satellite communication link or a simple multi-mode coexistence scheme. Existing solutions have the following shortcomings: First, distinguishing reporting methods solely by data volume fails to reflect the time-sensitivity differences inherent in the icing service itself. Large volumes of image data can easily fill the entire communication window, causing delays in sending icing alarm data that truly needs to be prioritized.

[0003] Second, relying solely on narrowband satellite links makes it difficult to simultaneously handle alarm and image services. Narrowband satellite links are suitable for transmitting alarm summaries and small message status data, but not for transmitting image data; Third, existing low-Earth orbit (LEO) satellite communication solutions focus more on link switching and signal quality than on proactive data scheduling planning around overhead communication windows. A key characteristic of LEO satellite communication is the existence of several predictable overhead communication windows each day. Current technologies lack systematic methods for prioritizing alarms within the window, providing low-time-sensitivity buffering outside the window, soft landing at the end of the window, and protecting against preemption within the window.

[0004] Fourth, it lacks preemption protection and breakpoint resume mechanisms within the window. If an emergency alarm occurs while a large image block is being transmitted within the window, it cannot be interrupted in time, which can easily lead to alarm delays or even data loss. Fifth, the lack of a soft landing mechanism at the end of the window makes it easy to start a new long task when the window is about to close, resulting in wasted bandwidth and repeated transmissions; Sixth, existing solutions, which rely on complex learning models for intelligent scheduling, are difficult to implement in real-time and in a lightweight manner in low-power embedded terminals.

[0005] In summary, a method is needed that can combine low-Earth orbit satellite over-the-top window prediction with a backup link and perform adaptive differentiated transmission based on data time sensitivity level. Summary of the Invention

[0006] In view of this, this application provides a terminal data adaptive transmission method with low-orbit satellite overpass window and backup link to solve the technical problems of existing field monitoring terminals in scenarios without public network coverage, which are difficult to simultaneously meet the requirements of second-level backhaul of high time-sensitive alarm data, efficient windowed transmission of low time-sensitive image data, preemption protection of low time-sensitive services by high time-sensitive services within the window, bandwidth waste at the end of the window, and low power consumption operation of the terminal.

[0007] This application proposes a terminal data adaptive transmission method for low-Earth orbit satellite overpass windows and safety links, characterized by the following steps: Establish a data time sensitivity classification model within the monitoring terminal, and divide the data to be sent into at least two levels, including first-level high time sensitivity data and second-level low time sensitivity data. Based on the terminal location and the received low-Earth orbit satellite ephemeris, calculate the over-the-top communication window of the low-Earth orbit satellite relative to the terminal, and obtain the remaining duration of the current window. Configure communication links, including at least a low-Earth orbit satellite link and a backup link; Differentiated transmission is implemented based on data time sensitivity level and window status: For Level 1 data, if the LEO satellite link is available, it is sent through the LEO satellite link; otherwise, the digest is sent through the backup link. For Level 2 data, it is sent through the LEO satellite link only when it is currently within the top window and the bandwidth requirement is met; otherwise, it is buffered and waited for transmission. If new first-level data is generated during the transmission of second-level data within the over-the-top window, the current transmission is interrupted and the breakpoint is saved. The newly generated first-level data is transmitted first, and transmission is resumed according to the breakpoint after the transmission is completed. When the remaining time of the window is less than or equal to the preset soft landing threshold, the initiation of a new second-level data transmission task is stopped.

[0008] Furthermore, in the time-sensitive classification model, the first level of high time-sensitive data includes alarm data for monitoring quantities exceeding thresholds, data for abnormal growth rates of monitoring quantities, abnormal data for terminal devices, abnormal power supply data, and event data manually set for emergency reporting; the second level of low time-sensitive data includes periodically collected routine status data, image data, and compressed image packages. For the i-th data item to be sent, define its remaining time margin: in, The maximum allowable transmission delay for this data. For the time when the data is generated, The current moment; The smaller the value, the higher the urgency of transmission; the maximum allowable transmission delay for first-level data is no more than 5 seconds, and the maximum allowable transmission delay for second-level data is no less than 300 seconds.

[0009] Furthermore, the calculation method for the over-the-top communication window is as follows: Let the current time be t, and the elevation angle of the low-orbit satellite at time t be... The preset minimum belief angle threshold is ,when ≥ The current communication window is determined; the remaining time of the window is... and the waiting time for the next window They are defined as follows: in, The end time of the current window. This is the start time of the next low-Earth orbit satellite overhead window; the aforementioned The value range is 20° to 30°.

[0010] Furthermore, the backup link is a BeiDou short message link, used to send a highly time-sensitive alarm summary outside the low-orbit window or when the low-orbit satellite link is unavailable; After the low-Earth orbit window is restored, the terminal retransmits the complete content of the high-time-sensitive data and associated image keyframes via the low-Earth orbit satellite link.

[0011] Furthermore, for the i-th data item to be sent, its scheduling priority value is defined as follows: in, As described in claim 2, the remaining time margin The data level factor is used, with higher values ​​for high-time-sensitivity data and lower values ​​for low-time-sensitivity data. The window adaptation factor is used when the data is in a low-level window and the remaining resources of the window are sufficient to accommodate the data; α, β, and γ are weighting coefficients; ε is a very small positive number; for first-level data, the highest priority is directly assigned without going through the regular sorting process.

[0012] Furthermore, in the steps of interrupting, saving breakpoints, and resuming transmission: let the total length of the current second-level data be... Successfully sent a length of Then the breakpoint offset ; The breakpoint information includes at least the data identifier, the number of bytes sent, the fragment number or frame sequence number, the verification information, and the remaining length to be sent.

[0013] Furthermore, it also includes an image data fragmentation scheduling step: for image data in the second level, if the size of a single image exceeds the capacity that the current window can carry, the image is fragmented and sent. Let the total size of the current image be M, and the available bandwidth of the low-Earth orbit satellite link be... The window protection time is The maximum fragment size allowed to be sent in the current window. ;in, The remaining window duration as described in claim 3; Size of each slice Satisfying 0 < ≤ Within each overlay window, image fragments not completed in the previous window are sent first, and the remaining capacity is used to send new image fragments; once all image fragments are confirmed to be received, the terminal deletes the local image cache.

[0014] Furthermore, the soft landing threshold is 20–60 seconds; when the remaining window duration is less than or equal to the soft landing threshold, the following is also executed: If second-level data is currently being sent, only the current data block is allowed to be sent completely, and no new image fragments are started; incomplete data and breakpoint information are written to the next window priority sending queue.

[0015] Furthermore, it also includes steps for sleeping outside the window and waking up in front of the window: When the terminal does not have any first-level data to be transmitted and is not currently within the low-track window, the terminal shuts down the high-power radio frequency module and only retains the monitoring and acquisition module, clock module and low-power timing module. Lead time before the start time of the next window Upon arrival, the terminal automatically wakes up the low-orbit communication module to complete link initialization and loading of the pending queue; The value range is 5 to 30 seconds.

[0016] Furthermore, according to any of the above-mentioned terminal data adaptive transmission methods, the method is applied to the transmission line icing monitoring scenario, and the first level of high time-sensitive data includes icing thickness exceeding the threshold data, icing growth rate abnormal data, terminal power supply abnormal data, and equipment self-test abnormal data. The second level of low-time-sensitivity data includes periodically collected icing thickness data, conductor temperature data, ambient temperature and humidity data, icing images, and compressed image packets; the backup link is the BeiDou short message link.

[0017] Compared with the prior art, the present invention has the following beneficial effects: 1. This application establishes a data time-sensitivity classification model that includes remaining time margin, dividing the data to be transmitted into high-time-sensitivity data with a maximum transmission delay of no more than five seconds and low-time-sensitivity data with a maximum transmission delay of no less than three hundred seconds. Combined with the dynamic calculation of the remaining time of the low-orbit satellite overpass window, a scheduling priority decision mechanism based on data level factor, time urgency, and window adaptation factor is formed. At the same time, the low-orbit satellite link is configured as the main link and the Beidou short message link as the backup link. This ensures that high-time-sensitivity data is transmitted immediately when the low-orbit satellite link is available, and alarm summaries are sent via the backup link when it is unavailable, and the complete data is retransmitted after the window is restored. Low-time-sensitivity data is only transmitted within the window and when the bandwidth is sufficient, otherwise it is buffered and waited for transmission. Thus, in scenarios without public network coverage, it achieves both reliable second-level transmission of alarm data and efficient windowed backhaul of status image data.

[0018] 2. In the process of transmitting low-time-sensitive data within the overhead window of a low-Earth orbit satellite, this application immediately interrupts the current transmission and saves the breakpoint information containing the number of bytes transmitted and the fragment number when new high-time-sensitive data is generated. Transmission resumes from the breakpoint after the high-time-sensitive data transmission is completed. At the same time, fragment scheduling and the maximum allowed fragment capacity constraint for the window are introduced for image data. When the remaining time of the window is less than or equal to the soft landing threshold of 20 to 60 seconds, the new task is stopped and the unfinished data is written into the priority transmission queue of the next window. Combined with the sleep strategy of shutting down the high-power radio frequency module outside the window and waking up the communication module five to thirty seconds in advance before the window, an adaptive transmission system with preemptive resumption, soft landing and low power linkage is constructed, which can run reliably in embedded terminals without the need for a complex learning model. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a flowchart of the terminal data adaptive transmission method of low-Earth orbit satellite over-the-top window and backup link in the embodiments of this application. It shows the complete steps from data time sensitivity classification, low-Earth orbit over-the-top window prediction, communication link configuration, differentiated transmission decision based on time sensitivity level and window state, preemptive transmission within the window, soft landing at the end of the window, to hibernation outside the window and wake-up before the window. Figure 2This is a flowchart of the over-the-top window prediction and differentiated transmission decision sub-process in the embodiments of this application, showing the calculation of the window start and end times based on the terminal position coordinates and the ephemeris of the low-orbit satellite, the determination of the minimum communication angle threshold, the update of the remaining duration of the current window, and the branch decision steps of adopting instant transmission and windowed transmission for the first-level data and the second-level data respectively. Figure 3 This is a flowchart of the preemptive resume and soft landing sub-process in the embodiments of this application. It shows the following steps during the second-level data transmission process: interruption triggered by the generation of first-level data, saving the breakpoint offset, priority transmission of first-level data, resumption of transmission from the breakpoint position after the first-level transmission is completed, and stopping the start of new tasks when the remaining window time drops to the soft landing threshold and writing unfinished data into the priority transmission queue of the next window. Figure 4 This is a schematic diagram of the structure of the monitoring terminal hardware module in the embodiments of this application; Figure 5 This is a flowchart of the data transmission timing process in the embodiments of this application, showing the entire timing relationship of the terminal from collecting ice thickness, triggering alarm when the ice growth rate exceeds the threshold, sending alarm summary of Beidou short message link, to starting low orbit satellite link image fragment transmission after the establishment of low orbit over-the-top window, preemption interruption within the window triggered by new alarm, breakpoint resumption, and retransmission of complete alarm data and image key frames after the window is restored. Detailed Implementation

[0021] In the following description, specific details such as particular system architectures and techniques are set forth for illustrative purposes and not for limitation, in order to provide a thorough understanding of the embodiments of this application. However, those skilled in the art will understand that this application may also be implemented in other embodiments without these specific details. In other instances, detailed descriptions of well-known systems, apparatuses, circuits, and methods have been omitted so as not to obscure the description of this application with unnecessary detail.

[0022] The terminal data adaptive transmission method for low-orbit satellite overpass window and backup link provided in this invention is particularly suitable for icing monitoring terminals in remote mountainous areas, high-altitude heavy icing areas and unattended power transmission lines without public network coverage. It can also be extended to field terminal data backhaul engineering scenarios with the characteristics of high timeliness for small data and low timeliness for large data, such as wildfire monitoring, tower tilt monitoring, and micro-meteorological monitoring.

[0023] During the operation of field monitoring terminals, the terminals need to collect two types of data: one type is alarm data such as ice thickness exceeding the threshold and abnormal growth rate, as well as structured status data such as equipment self-test status. This type of data is small in volume but requires reporting within seconds; the other type is large-capacity data such as ice images and keyframe images, mainly used for manual verification, allowing for delays of minutes or even longer. However, traditional methods usually only distinguish the reporting method according to the size of the data, without reflecting the time sensitivity differences of the icing service itself. Large-capacity image data can easily fill the limited over-the-top communication window of low-Earth orbit satellites, causing alarm data that really needs to be sent first to be delayed. Although some improved methods have introduced low-Earth orbit satellite communication, they focus more on link switching and signal quality, without actively planning data scheduling around the over-the-top window. They lack a systematic mechanism for prioritizing alarms within the window, low-time-sensitivity buffering outside the window, soft landing at the end of the window, and preemption protection within the window. It is also difficult to achieve lightweight real-time scheduling in low-power embedded terminals.

[0024] The aforementioned shortcomings make it difficult to reconcile the contradiction between the real-time nature of high-time-sensitivity alarms and the transmissibility of low-time-sensitivity images under limited low-orbit satellite window resources. This results in prominent issues such as wasted window bandwidth, duplicate transmissions, and alarm delays, affecting timely early warning and response decisions for icing disasters.

[0025] This invention establishes a time-sensitive classification model for icing monitoring data, dividing the data into high-time-sensitive and low-time-sensitive categories, and defines the remaining time margin as a quantitative indicator of transmission urgency. It calculates the overpass communication window and its remaining duration using low-Earth orbit (LEO) satellite ephemeris data; configures the LEO satellite link as the primary link and the BeiDou short message link as the backup link; and makes differentiated transmission decisions based on data level and window status. High-time-sensitive data is transmitted immediately via the LEO satellite link or a summary is sent via the backup link, while low-time-sensitive data is transmitted only within the window and when bandwidth is sufficient, otherwise it is buffered. During the transmission of low-time-sensitive data within the window, if new high-time-sensitive data is generated, the transmission is immediately interrupted and the breakpoint is saved, prioritizing the transmission of high-time-sensitive data, and resuming transmission after completion. When the remaining window duration is less than the soft landing threshold, new tasks are stopped from starting. Simultaneously, it combines low-power management with sleep mode outside the window and wake-up mode before the window, thus constructing a complete, lightweight, and embeddable adaptive data transmission method for field monitoring terminals.

[0026] For ease of description, the symbols for each physical quantity in this manual are uniformly agreed upon as follows: This represents the remaining time margin for the i-th data item to be sent, in seconds. This represents the maximum allowed transmission delay for the i-th data item to be sent, in seconds. The time when the i-th piece of data to be sent was generated is indicated; t represents the current time. This indicates the remaining duration of the current low-orbit overpass window, in seconds. This indicates the waiting time until the start of the next low-orbit overhead window, in seconds. , These represent the end time of the current window and the start time of the next window, respectively. This represents the elevation angle of a low-orbit satellite relative to the terminal at time t. This indicates the preset minimum belief angle threshold; This represents the scheduling priority value of the i-th data item to be sent; Indicates the data rank factor; α represents the window adaptation factor; β, γ represent weighting coefficients; ε represents a very small positive number to prevent the denominator from being zero; L represents the total length of the current second-level data. This indicates that the length has been successfully sent. This represents the breakpoint offset; M represents the current total image size. Indicates the available bandwidth of the low-orbit link. Indicates the window protection time. This indicates the maximum fragment size that the current window is allowed to send. This represents the size of the m-th image slice; Indicates the soft landing threshold. This indicates the wake-up lead time before the window.

[0027] like Figure 1 As shown, the adaptive transmission method provided in this embodiment mainly includes steps such as data classification, window prediction, link configuration, differentiated decision-making, preemptive resumption, soft landing, and sleep wake-up.

[0028] This embodiment uses a heavy icing monitoring terminal for a high-altitude transmission line as an example. The terminal is installed near a tower on a mountain ridge, where there is no public network coverage. The terminal is equipped with an icing thickness sensor, an ambient temperature and humidity sensor, a conductor temperature sensor, an image acquisition module, a low-orbit satellite communication module, and a BeiDou short message module. For example... Figure 4 As shown, the terminal also integrates a power management module and a main control unit (containing a data acquisition interface, a time-sensitive classification and scheduling module, a window calculation module, a storage module, and a clock module). These modules work together to achieve adaptive transmission.

[0029] In application, establishing a data time-sensitivity classification model is the process of systematically classifying all data to be sent according to business timeliness requirements within the monitoring terminal. The terminal identifies and judges each piece of data to be sent, classifying it into either Level 1 (high-time-sensitivity data) or Level 2 (low-time-sensitivity data). Level 1 high-time-sensitivity data refers to alarm information that must be delivered to the monitoring center as soon as possible upon generation. If the transmission delay exceeds the business-allowed time limit, the monitoring center will miss the optimal handling opportunity, leading to security risks. Level 2 low-time-sensitivity data refers to status and image information that can be accumulated over a period of time and then transmitted in a concentrated manner; its business value will not be significantly reduced by transmission delays of several minutes to tens of minutes. By establishing a two-level classification instead of processing all data uniformly, the terminal can prioritize the transmission of the most critical information with limited communication resources, while reserving reasonable transmission paths and sending opportunities for low-time-sensitivity data.

[0030] like Figure 2 As shown, calculating the low-Earth orbit (LEO) satellite overpass communication window is a prerequisite for the terminal to implement proactive transmission planning. LEO satellites continuously orbit, and relative to a fixed ground terminal, they only pass over the terminal and reach a communicable elevation angle range during specific time periods each day; this period is called the overpass communication window. The terminal has a built-in ephemeris reception and window calculation module. Using the terminal's installation location coordinates as the observation point, and combining ephemeris parameters obtained from LEO satellite broadcasts, it predicts the future elevation angle changes of each LEO satellite, thereby predicting the start and end times of each overpass window. Obtaining the remaining duration of the current window is a key input for scheduling decisions. Based on this, the terminal determines how much available time remains within the current window to rationally arrange the scale of transmission tasks and avoid initiating transmission tasks exceeding the window's capacity when time is insufficient.

[0031] In applications, configuring communication links is the process of establishing a multi-channel guarantee system for terminals. The low-Earth orbit (LEO) satellite link, as the primary service link, possesses high transmission bandwidth, capable of handling the transmission needs of status data and image data, fully utilizing communication resources during the overhead transit window. The backup link, as a supplementary communication means, is specifically designed to deliver summaries of high-time-sensitive data to the monitoring center even after the LEO window ends or when the LEO satellite link becomes unavailable. The core significance of the dual-link configuration is that the timely delivery of high-time-sensitive data does not depend on whether the LEO satellite is within its overhead transit window, thus eliminating the risk of alarm delays due to excessively long window waiting times. It also compensates for the inability of a single narrowband link to handle large-capacity image data; the two types of links each perform their respective functions, forming a complementary relationship.

[0032] In application, differentiated transmission decision-making is a process of determining the transmission path based on the data's time sensitivity level and the current window status. For Level 1 high-time-sensitivity data, the terminal first checks whether the LEO satellite link is currently communicable. If the LEO satellite link is available, the complete high-time-sensitivity data is immediately transmitted via it. If the LEO satellite link is unavailable, the terminal immediately switches to the backup link to transmit a compressed high-time-sensitivity data digest, ensuring that the monitoring center can receive alarm information in a timely manner. The method of delivery of high-time-sensitivity data is independent of the window status, and delays in transmission due to waiting for the LEO window are not allowed. For Level 2 low-time-sensitivity data, the terminal determines whether it is currently within the LEO overpass communication window and whether the available bandwidth within the window meets the preset requirements. Only when both conditions are met is the data transmitted via the LEO satellite link. Otherwise, the data is written to a local buffer queue to wait for the next overpass window. Low-time-sensitivity data is not transmitted via the backup link to avoid consuming the limited capacity resources of the backup link.

[0033] like Figure 3 As shown, preemption protection within the window and breakpoint resumption are the core mechanisms for handling sudden bursts of high-time-sensitive data. When second-level low-time-sensitive data is being transmitted within the low-orbit window, if first-level high-time-sensitive data is generated at this time, the transmission of the low-time-sensitive data is immediately interrupted. The terminal records the number of bytes of the low-time-sensitive data that have been successfully transmitted at the moment of interruption, and saves this breakpoint information, along with data identifiers and verification information, to the local storage area. Subsequently, all transmission resources are switched to transmit the newly generated high-time-sensitive data. After the high-time-sensitive data transmission is completed, the terminal reads the breakpoint information from the local storage area and continues to transmit the remaining low-time-sensitive data content from the position where it was successfully transmitted. This ensures that the transmission progress of the low-time-sensitive data is not lost due to preemption, the overall window utilization is guaranteed, and the bytes that have already been transmitted do not need to be retransmitted.

[0034] In applications, the soft landing mechanism is a protective measure to prevent the initiation of transmission tasks that cannot be completed within the current window when it is about to close. When the overshoot window reaches its end, the low-Earth orbit satellite link will quickly break down because the satellite elevation angle falls below the communication threshold. If a large-scale, low-time-sensitive data transmission task is initiated near the end of the window, the task is highly likely to be forcibly interrupted when the window closes, not only wasting the bandwidth resources already transmitted but also causing the receiving end to receive incomplete data packets. The soft landing mechanism monitors the remaining duration of the current window in real time. When the remaining duration drops below the soft landing threshold, it proactively stops initiating new low-time-sensitive data transmission tasks, allowing the currently ongoing data blocks to complete transmission naturally and ending the current window's transmission. The remaining untransmitted data and breakpoint information are sequentially written into the priority transmission queue for the next window, where they are processed with priority when the next window arrives, ensuring the continuity of transmission progress.

[0035] like Figure 5As shown, in a heavy icing monitoring scenario for a power transmission line, the terminal continuously collects icing thickness and on-site image data. The time-sensitive grading module classifies icing thickness and images that do not exceed the threshold into the second-level cache. The window calculation module continuously refreshes the current over-the-top window status. When the low-orbit satellite over-the-top window is established, the terminal wakes up the low-orbit communication module and starts transmitting cached images. If the icing thickness suddenly exceeds the threshold and triggers an alarm, the transmission control module immediately interrupts image transmission, saves the breakpoint offset, and prioritizes pushing icing alarm data. After the alarm is completed, the image transmission resumes from the breakpoint position. If the remaining window duration drops below the soft landing threshold, the startup of new segments stops. The current segment that has been completed stops after it finishes normally. The remaining image segments are written into the next window priority queue. The entire process has extremely low computing power requirements for the terminal's embedded processor and can run stably in low-power mode.

[0036] The identification of data time sensitivity levels can be achieved through rule matching based on a preset parameter table. The terminal stores the mapping relationship between each data type and its corresponding time sensitivity level. When each piece of data to be sent is received, the level is directly confirmed by looking up the table, eliminating the need for complex online calculations and achieving high efficiency and stability. Alternatively, the time sensitivity level can be dynamically adjusted based on the deviation between the current monitored value and the threshold. When the deviation is large, the time sensitivity level is automatically increased to high, and when the deviation narrows, it is reduced back to low, improving the flexibility and responsiveness of the classification. The calculation of the remaining window duration can be performed using a pre-loaded ephemeris offline calculation method. Before each window arrives, the terminal predicts the next window and stores the start and end times in a cache for direct reading by the transmission scheduling module. Alternatively, a real-time elevation angle calculation method can be used, updating the satellite elevation angle at fixed intervals and comparing it with a threshold to dynamically determine the window status. The two methods can be combined to balance accuracy and real-time performance.

[0037] This solution completely decouples high-time-sensitivity data from low-time-sensitivity data in terms of transmission path and timing. The transmission latency of high-time-sensitivity data is not constrained by the low-track window waiting time, and the transmission efficiency of low-time-sensitivity data is not limited by the narrowband constraints of the backup link. Both types of services receive optimal transmission guarantees on their most suitable channels. The in-window preemption mechanism ensures that high-time-sensitivity data can obtain transmission resources at any time, and the soft-landing mechanism avoids bandwidth waste and incomplete data packet problems caused by blindly starting tasks before the window closes. The overall solution has extremely low requirements for terminal computing power and storage, making it suitable for long-term stable operation in low-power embedded terminals.

[0038] In application, the specific identification range of Level 1 high-time-sensitivity data and Level 2 low-time-sensitivity data is determined based on the sensitivity of various data in the icing monitoring business to the timing of handling. Monitoring quantity exceeding threshold alarm data refers to alarms generated when the measured values ​​of key physical quantities such as icing thickness exceed preset safety boundaries. Delayed transmission may cause the monitoring center to miss the optimal icing melting opportunity, therefore it is classified as Level 1. Abnormal growth rate monitoring quantity data refers to warnings generated when the growth rate of icing thickness per unit time exceeds the normal range. Abnormal growth rate is often an early signal of large-scale icing disasters and also requires immediate reporting. Terminal equipment anomaly data and power supply anomaly data reflect the working status of the monitoring terminal itself. Terminal failure or insufficient power supply will lead to a decrease in the reliability of subsequent monitoring data, therefore it is also classified as Level 1 to ensure that the monitoring center can understand the terminal's health status in a timely manner and arrange maintenance. Event data manually set for emergency reporting is manually marked by maintenance personnel according to the actual situation on site and assigned the highest transmission priority to cover special situations not covered by preset rules. Level 2 low-time-sensitivity data includes periodically collected routine state data, which is valuable for statistical trend analysis but the transmission delay of a single data point has limited impact on decision-making, as well as image data and compressed image packets. Image data is mainly used for manual review and fine analysis, allowing transmission within minutes or even longer delays.

[0039] For the i-th data item to be sent, define its remaining time margin. ,in The maximum allowable transmission delay for this data. For the time when the data is generated, This refers to the current moment. The smaller the value, the higher the urgency of transmission. The maximum allowable transmission delay for Level 1 data is no more than 5 seconds, and the maximum allowable transmission delay for Level 2 data is no less than 300 seconds. In actual operation, the terminal scheduling module continuously maintains a queue containing all data entries to be sent. Each scheduling cycle calculates the individual values ​​for each entry in the queue at the current time t. Value, will The smallest first-level data is marked as the most urgent to send; if the LEO satellite link is available, it will be pushed immediately; if the LEO satellite link is unavailable, a summary will be sent via a backup link. Second-level data... The calculation results are used for sorting the submissions within the window. Smaller, low-time-sensitivity data has a higher transmission priority when queued within a window.

[0040] in, The value can be set using a system-preset fixed value, uniformly setting a standard allowable delay for all data of the same type. This method is simple to configure and its behavior is predictable. Alternatively, it can be dynamically assigned based on data content. For example, the larger the ice thickness exceeds the threshold, the higher the corresponding value will be. The smaller the value, the more urgent the scheduling weight will be for extreme alarms compared to minor over-threshold alarms. The update frequency can be calculated in real time before each scheduling decision to ensure that the scheduling priority always reflects the latest time limit status, or it can be updated in batches at fixed periods to reduce computational overhead.

[0041] In applications, the over-the-top communication window is calculated based on the elevation angle of the low-Earth orbit satellite relative to the terminal. Based on this, let the current time be t, and the elevation angle of the low-orbit satellite at time t be... The preset minimum belief angle threshold is ,when The system determines whether the user is currently in a communicable window. The remaining window duration... and the waiting time for the next window They are defined as follows: in The end time of the current window. This marks the start time of the next low-Earth orbit satellite overhead window. The value range is 20° to 30°. The terminal uses a pre-loaded ephemeris to refresh the prediction results of each overhead window at midnight every day, obtaining the start time of each window and... The value is stored in a local timetable. During operation, the terminal scheduling module reads the current time t every few seconds and compares it with the value of the most recent window in the timetable. Comparison, Real-time Updates ,when The soft landing logic is triggered when the temperature drops to the soft landing threshold. Update after resetting to zero The value is waiting for the next window.

[0042] in, The calculation can be performed using an analytical method based on terminal coordinates and pre-loaded ephemeris. The satellite elevation angle at any time can be directly derived using satellite orbit elements and terminal latitude and longitude information. This method is highly accurate and does not rely on real-time data connection. Alternatively, a method based on measured signal strength can be used for auxiliary correction. When the terminal actually receives low-orbit satellite signals, the accuracy of the elevation angle prediction can be verified by the measured signal strength, and the deviation can be corrected in subsequent calculations. The time can be obtained by offline prediction of ephemeris files and then storing them in a local timetable, or by predicting the start time of the next window in real time at the end of each window.

[0043] In application, the backup link is the BeiDou short message link. The BeiDou short message system belongs to the high-orbit satellite communication system, with an orbital altitude of approximately 36,000 kilometers. Its coverage is unobstructed from the ground, and it can be used stably even in remote mountainous areas and high-altitude heavy icing regions without public network coverage. Furthermore, signal coverage is independent of whether a satellite is passing overhead; communication can be initiated at any time as long as the terminal and receiving equipment are powered on. The limited message length of each BeiDou short message communication is suitable for transmitting compressed, high-time-sensitive alarm summaries. These summaries include core fields such as alarm type, occurrence time, key measurements, and terminal identifier. After the low-orbit window recovers, the terminal retransmits the complete content of the high-time-sensitive data and associated image keyframes via the low-orbit satellite link. This allows the monitoring center to obtain a complete event record when subsequent windows arrive after receiving the initial alarm summary, supporting detailed review and archiving analysis of icing events.

[0044] The compression method for alarm summaries can employ fixed-field format encoding, where the alarm type, time, value, and terminal identifier are each encoded with a fixed number of bytes and then concatenated to reduce redundant bytes and ensure that the summary message meets the single message length limit of BeiDou short messages. Alternatively, a differential encoding method can be used, transmitting only the difference between the current measurement value and the previous normal value instead of the absolute value, further compressing the summary byte count. The timing for triggering retransmission after the low-orbit window recovery can be either immediate push after window establishment or writing the retransmission task into a priority sending queue and scheduling it according to priority in the next window.

[0045] In the application, for the i-th data to be sent, its scheduling priority value is defined as follows: in The data level factor is used, with higher values ​​for high-time-sensitivity data and lower values ​​for low-time-sensitivity data. The window adaptation factor is used, taking a higher value when the data is in a low-level window and the window's remaining resources are sufficient to handle the data; α, β, and γ are weighting coefficients; ε is a very small positive number. First-level data is directly assigned the highest priority, without undergoing a regular sorting process. Three-factor weighted... The formula integrates three independent dimensions—data level, time urgency, and window resource matching—into a directly comparable priority value. The terminal does not need to design separate branch rules for each data combination, resulting in a unified scheduling logic with good scalability.

[0046] To more clearly illustrate the working process of the scheduling priority formula, a specific calculation example is given below. Suppose that within a certain scheduling period, there are two low-time-sensitivity data items of the second level waiting to be sent in the terminal buffer queue: Data A is periodically collected conductor temperature data, whose maximum allowable transmission delay... =300 seconds, the time of generation is 100 seconds from the current time, that is =200 seconds; Data B is a fragment of the icing image, with a maximum allowable transmission delay. =300 seconds, the time of generation is 170 seconds from the current time, that is =130 seconds. Assume the current window is within the low-orbit overshoot window, and the remaining resources of the current window are sufficient to hold data A but insufficient to hold the complete data B, then the window adaptation factor is... =1、 =0; Both data points are at the second level, data level factor. = =0.5; take weighting coefficients α=0.3, β=0.5, γ=0.2, ε=10 -6 Substituting into the aforementioned scheduling priority formula, we obtain: = 0.3×0.5 + 0.5 / (200+10 -6 ) + 0.2×1 ≈ 0.15 + 0.0025 + 0.2 = 0.3525 = 0.3 × 0.5 + 0.5 / (130 + 10) -6 ) + 0.2×0 ≈ 0.15 + 0.003846 + 0 ≈ 0.1538 Therefore, although data B is more urgent than data A in terms of time constraint, the remaining resources of the current window are insufficient to support the complete data B. Since the priority value of data A is 0, its scheduling priority is significantly lowered. Therefore, in this scheduling cycle, the terminal prioritizes sending data A; data B enters a waiting state. After data A is sent, if the remaining resources in the window meet the carrying requirements of B, As the value of B changes from 0 to 1, its P value increases and it enters the transmission sequence. If B does not get a transmission opportunity by the end of the current window, its breakpoint information and complete content are written into the priority transmission queue of the next window via the soft landing mechanism. The example shows that the scheduling priority formula achieves coordinated decision-making between time urgency and window resource availability through the weighting of three independent factors, avoiding the resource waste that may occur when sorting only by time limit and then being forcibly interrupted by window closing.

[0047] The weighting coefficients α, β, and γ can be set using pre-set fixed values ​​based on engineering experience. During the system design phase, the ratios of these three factors are determined based on the relative importance of timeliness, deadline urgency, and window resource matching, and then written into the terminal firmware. Alternatively, the weighting coefficients can be dynamically adjusted by maintenance personnel via remote commands. Preferably, α ranges from 0.2 to 0.4, β from 0.4 to 0.6, and γ from 0.2 to 0.4, satisfying α + β + γ = 1. More preferably, α = 0.3, β = 0.5, and γ = 0.2. In this case, the scheduling priority is dominated by the urgency of the deadline, with window resource matching providing secondary correction. The data level factor is mainly used to distinguish data in the second level but with different business values; for example, prioritizing keyframe images over ordinary compressed image packets. When the business side further increases the alarm priority requirements, α can be increased to 0.4 and γ can be decreased accordingly; when the requirements for window resource utilization are higher and it is desired that large-size data be prioritized for matching large windows, γ can be increased to 0.4 and α can be decreased accordingly. The specific values ​​of the weighting coefficients can be preset according to the above-mentioned preferred range when the terminal is first deployed, and dynamically adjusted within the above range through remote commands after the terminal is put into operation, so as to adapt to the actual engineering needs under different geographical locations and different LEO constellation overpass frequencies. The value of Wi can be determined in a Boolean binary manner, that is, when it is in a LEO window and the remaining resources of the window are sufficient to carry the data. =1, otherwise =0; Alternatively, a method of continuously taking values ​​according to the capacity matching ratio can be used, for example, let ,in The maximum fragment size allowed to be sent in the current window. Let be the size of the i-th data to be sent in bytes. This continuous value method allows the matching degree between the data size and the remaining window capacity to be precisely reflected in the scheduling priority value.

[0048] In the application, the specific operations for interrupting, saving breakpoints, and resuming transmission are as follows: Let the total length of the current second-level data be... Successfully sent a length of Then the breakpoint offset The breakpoint information includes at least the data identifier, the number of bytes sent, the fragment number or frame sequence number, checksum information, and the remaining length to be sent. When Level 2 data is being transmitted within the low-orbit window, if Level 1 high-time-sensitivity data is newly generated, the current transmission is immediately interrupted, the breakpoint information is saved, and Level 1 data is transmitted first. Transmission resumes from the breakpoint position after transmission is complete. The breakpoint information includes at least the data identifier, the number of bytes sent, the fragment number or frame sequence number, checksum information, and the remaining length to be sent.

[0049] Of which, the number of bytes sent The record can be obtained by the receiving end sending back a fragment-by-fragment acknowledgment response. The terminal obtains the accurate result by multiplying the sequence number of the last fragment received in the acknowledgment response by the fragment size. Alternatively, a local send counter can be maintained by the terminal to record the total number of bytes pushed to the communication module's send buffer. The approximate value is obtained. Breakpoint information can be stored by writing to non-volatile memory to ensure that the breakpoint information can still be read when the terminal restarts after an unexpected power outage. Alternatively, it can be stored by writing to memory only to reduce the number of writes to non-volatile memory.

[0050] The application also includes an image data fragmentation and scheduling step. For image data in the second level, if the size of a single image exceeds the capacity of the current window, the image is fragmented and sent. Let the total size of the current images be M, and the available bandwidth of the low-Earth orbit satellite link be... The window protection time is The maximum fragment size allowed to be sent in the current window. Size of each slice Satisfying 0 < ≤ Within each overlay window, image fragments not completed in the previous window are sent first, and the remaining capacity is used to send new image fragments. Once all image fragments have been confirmed as received, the terminal deletes the local image buffer.

[0051] in, The available bandwidth can be obtained based on real-time reports from the communication module, or it can be based on historical statistical average bandwidth. Image slice size The determination can be made by calculating before each fragmentation. Then let equal Alternatively, a fixed segment size can be preset.

[0052] In application, the soft landing threshold is 20–60 seconds. When the remaining window duration is less than or equal to this soft landing threshold, the following actions are also taken: if second-level data is currently being transmitted, only the current data block is allowed to complete transmission, and no new image fragments are started; incomplete data and breakpoint information are written to the priority transmission queue for the next window. The soft landing threshold can be set by operations and maintenance personnel in the system configuration file according to the actual link conditions, or it can be automatically estimated by the terminal after several window runs by statistically averaging the fragment transmission time and response time. The value is updated dynamically afterward.

[0053] The application also includes out-of-window sleep and pre-window wake-up steps. When the terminal has no first-level data to be transmitted and is not currently within a low-level window, the terminal shuts down the high-power RF module, retaining only the monitoring and acquisition module, clock module, and low-power timing module. The advance time before the start of the next window is calculated. Upon arrival, the terminal automatically wakes up the low-orbit communication module to complete link initialization and loading of the pending queue. The value range is 5 to 30 seconds. Early wake-up ensures that the link has been initialized and is ready when the window officially starts. At the same time, the pending queue loading operation is performed in parallel during link initialization, reading the data entries to be sent in this window from the storage area into memory, and immediately entering the data sending process when the window starts.

[0054] The high-power module can be shut down by either controlling the communication module to enter a deep sleep mode via software instructions or by directly cutting off the power supply to the communication module. The value can be set using a static preset method based on the nominal initialization time of the communication module plus a fixed margin, or it can be set dynamically by recording the time difference between the actual initialization completion time and the window start time after each wake-up and calculating the historical average value.

[0055] In application, the above method is used in transmission line icing monitoring scenarios. The first level of high-time-sensitive data includes data on icing thickness exceeding the threshold, abnormal icing growth rate, abnormal terminal power supply, and abnormal equipment self-test data. The second level of low-time-sensitive data includes periodically collected icing thickness data, conductor temperature data, ambient temperature and humidity data, icing images, and compressed image packets. The backup link is the BeiDou short message link. During a period of continuous cooling, the terminal detected an icing thickness increase of 8mm within one hour during the low-Earth orbit (LEO) window gap in the early morning. This increase exceeded the preset abnormal growth rate threshold. The time-sensitive classification module marked this abnormal icing growth rate data as Level 1. The scheduling module, detecting that the terminal was not currently within the LEO overpass window, immediately activated the BeiDou short message module, sending a summary message containing the abnormal growth rate alarm type, current time, current icing thickness, growth rate value, and terminal number. Within minutes, the monitoring center's maintenance personnel received the summary, determined the situation was severe, and initiated the icing melt emergency procedure. Approximately two hours later, the LEO window was established, and the terminal uploaded the complete one-hour icing thickness change sequence data and corresponding keyframe images via the LEO satellite link, supporting detailed post-event analysis. The entire response chain covered a complete closed loop from alarm outside the window to detailed data retransmission within the window.

[0056] The above description is merely a preferred embodiment of this application and is not intended to limit the scope of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A terminal data adaptive transmission method for low-Earth orbit satellite overpass window and backup link, characterized in that, Includes the following steps: Establish a data time sensitivity classification model within the monitoring terminal, and divide the data to be sent into at least two levels, including first-level high time sensitivity data and second-level low time sensitivity data. Based on the terminal location and the received low-Earth orbit satellite ephemeris, calculate the over-the-top communication window of the low-Earth orbit satellite relative to the terminal, and obtain the remaining duration of the current window. Configure communication links, including at least a low-Earth orbit satellite link and a backup link; Differentiated transmission is implemented based on data time sensitivity level and window status: For Level 1 data, if the LEO satellite link is available, it is sent through the LEO satellite link; otherwise, the digest is sent through the backup link. For Level 2 data, it is sent through the LEO satellite link only when it is currently within the top window and the bandwidth requirement is met; otherwise, it is buffered and waited for transmission. If new first-level data is generated during the transmission of second-level data within the over-the-top window, the current transmission is interrupted and the breakpoint is saved. The newly generated first-level data is transmitted first, and transmission is resumed according to the breakpoint after the transmission is completed. When the remaining time of the window is less than or equal to the preset soft landing threshold, the initiation of a new second-level data transmission task is stopped.

2. The terminal data adaptive transmission method according to claim 1, characterized in that, In the time-sensitive classification model, the first level of high time-sensitive data includes alarm data for monitoring quantities exceeding thresholds, data for abnormal growth rates of monitoring quantities, abnormal data for terminal devices, abnormal data for power supply, and event data manually set for emergency reporting; the second level of low time-sensitive data includes periodically collected routine status data, image data, and compressed image packages. For the i-th data item to be sent, define its remaining time margin: in, The maximum allowable transmission delay for this data. For the time when the data is generated, The current moment; The smaller the value, the higher the urgency of transmission; the maximum allowable transmission delay for first-level data is no more than 5 seconds, and the maximum allowable transmission delay for second-level data is no less than 300 seconds.

3. The terminal data adaptive transmission method according to claim 1, characterized in that, The calculation method for the over-the-top communication window is as follows: Let the current time be t, and the elevation angle of the low-orbit satellite at time t be... The preset minimum belief angle threshold is ,when ≥ The current communication window is determined; the remaining time of the window is... and the waiting time for the next window They are defined as follows: in, The end time of the current window. This is the start time of the next low-Earth orbit satellite overhead window; the aforementioned The value range is 20° to 30°.

4. The terminal data adaptive transmission method according to claim 1, characterized in that, The backup link is the BeiDou short message link, which is used to send a highly time-sensitive alarm summary when the low-orbit window is outside or when the low-orbit satellite link is unavailable. After the low-Earth orbit window is restored, the terminal retransmits the complete content of the high-time-sensitive data and associated image keyframes via the low-Earth orbit satellite link.

5. The terminal data adaptive transmission method according to claim 1, characterized in that, For the i-th data item to be sent, define its scheduling priority value: in, As described in claim 2, the remaining time margin The data level factor is used, with higher values ​​for high-time-sensitivity data and lower values ​​for low-time-sensitivity data. The window adaptation factor is used when the data is in a low-level window and the remaining resources of the window are sufficient to accommodate the data; α, β, and γ are weighting coefficients; ε is a very small positive number; for first-level data, the highest priority is directly assigned without going through the regular sorting process.

6. The terminal data adaptive transmission method according to claim 1, characterized in that, In the steps of interrupting, saving breakpoints, and resuming transmission: Let the total length of the current second-level data be... Successfully sent a length of Then the breakpoint offset ; The breakpoint information includes at least the data identifier, the number of bytes sent, the fragment number or frame sequence number, the verification information, and the remaining length to be sent.

7. The terminal data adaptive transmission method according to claim 1, characterized in that, It also includes an image data fragmentation scheduling step: for image data in the second level, if the size of a single image exceeds the capacity that the current window can carry, the image is fragmented and sent. Let the total size of the current image be M, and the available bandwidth of the low-Earth orbit satellite link be... The window protection time is The maximum fragment size allowed to be sent in the current window. ;in, The remaining window duration as described in claim 3; Size of each slice Satisfying 0 < ≤ Within each overlay window, image fragments not completed in the previous window are sent first, and the remaining capacity is used to send new image fragments; once all image fragments are confirmed to be received, the terminal deletes the local image cache.

8. The terminal data adaptive transmission method according to claim 1, characterized in that, The soft landing threshold is 20–60 seconds; when the remaining window duration is less than or equal to the soft landing threshold, the following also applies: If second-level data is currently being sent, only the current data block is allowed to be sent completely, and no new image fragments are started; incomplete data and breakpoint information are written to the next window priority sending queue.

9. The terminal data adaptive transmission method according to claim 1, characterized in that, It also includes the steps of sleeping outside the window and waking up in front of the window: When the terminal does not have any first-level data to be transmitted and is not currently within the low-track window, the terminal shuts down the high-power radio frequency module and only retains the monitoring and acquisition module, clock module and low-power timing module. Lead time before the start time of the next window Upon arrival, the terminal automatically wakes up the low-orbit communication module to complete link initialization and loading of the pending queue; The value range is 5 to 30 seconds.

10. The terminal data adaptive transmission method according to any one of claims 1 to 9, characterized in that, The method is applied to the icing monitoring scenario of transmission lines. The first level of high time-sensitive data includes icing thickness exceeding the threshold data, icing growth rate abnormal data, terminal power supply abnormal data, and equipment self-test abnormal data. The second level of low-time-sensitivity data includes periodically collected icing thickness data, conductor temperature data, ambient temperature and humidity data, icing images, and compressed image packets; the backup link is the BeiDou short message link.

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