Low-power-consumption data transmission method for low-orbit satellite Internet of Things terminal

Abstract

The invention discloses a low-power-consumption data transmission method for a low-orbit satellite internet-of-things terminal, and relates to the technical field of satellite communication, and the method comprises the steps: calculating an overhead time window through employing a satellite ephemeris and a terminal GNSS coordinate, and introducing atmospheric refraction and movement position correction; determining a wake-up advance containing equipment preheating and error compensation, and waking up the terminal before the window; the battery voltage is collected, and three strategies of band cascade coding, compression and error correction sending and only data abstract sending are divided according to the electric quantity; receiving satellite dynamic energy factors to adjust transmitting power and the number of data packets; and after completion, entering dormancy, and only leaving a low-power-consumption clock to maintain a time sequence. Through accurate awakening, hierarchical transmission, double-clock calibration and self-learning, the terminal endurance is prolonged, the access success rate and the link utilization rate are improved, and power consumption and reliability are balanced.

Description

Technical Field

[0001] The present invention relates to the field of satellite communication technology, and in particular to a low-power consumption data transmission method for a low-orbit satellite Internet of Things terminal. Background Art

[0002] Satellite IoT provides critical communications support for remote areas, oceans, and other areas without ground-based base station coverage. However, existing technologies have significant limitations. While high-orbit satellites offer wide coverage, their orbital altitude of approximately 35,000 kilometers results in round-trip latency of 500-600 milliseconds, significantly higher than the 20 milliseconds achieved by terrestrial fiber optic communications, making them difficult to meet real-time demands. While low-orbit satellites reduce latency to 20-50 milliseconds, limited spectrum resources and transmission capacity still constrain data-intensive applications, such as video surveillance and remote sensing, which are often limited by insufficient bandwidth.

[0003] Traditional satellite IoT terminal transmission schemes suffer from numerous flaws. Most terminals rely on continuous scanning or timed wake-up methods to await satellite signals, wasting significant energy in ineffective waiting. Data transmission strategies are fixed, disregarding remaining battery power. Even when the battery is low, attempts to transmit the full data packet, resulting in ineffective energy consumption before the battery is depleted. Clock system designs are imbalanced, either relying on a high-precision clock, which results in excessive power consumption, or relying on a low-precision clock, which causes time deviation and compromises communication timing accuracy. Furthermore, existing solutions lack mechanisms for dynamically adapting to link status and cannot adjust transmission parameters based on satellite load and link quality, which can easily lead to congestion or transmission failures.

[0004] As IoT terminals demand low power consumption and long battery life, existing technologies are increasingly lacking in areas such as satellite overpass prediction accuracy, wake-up timing optimization, adaptive power transmission, and clock power balance. This results in short battery life and low access success rates for terminals, making them difficult to adapt to battery- or solar-powered devices. Therefore, the industry urgently needs to develop a low-power data transmission method for low-orbit satellite IoT terminals that can accurately predict communication windows, dynamically adjust transmission strategies, and balance clock accuracy and power consumption. Summary of the Invention

[0005] The present invention proposes a low-power data transmission method for low-orbit satellite Internet of Things terminals to solve the problems mentioned in the above-mentioned prior art.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions: A low-power data transmission method for a low-orbit satellite Internet of Things terminal, characterized by comprising the following steps: Calculate the satellite overpass time window: Use satellite ephemeris data, combined with the geographical location coordinates obtained by the terminal through the GNSS module, and calculate the satellite and terminal overpass visible time window based on the Kepler orbit equation. , ]; atmospheric refraction correction is introduced during the calculation process, and the correction amount =0.0015・ ,in is the satellite elevation angle; for mobile terminals, the position change correction is calculated based on its movement speed =v・ , where v is the terminal velocity, is the predicted duration; Determine the wake-up lead time: Wake-up lead time Warm-up time of the device and prediction error compensation composition; The fixed value is 100ms, including 30ms for the RF module phase-locked loop to stabilize and 70ms for the power amplifier to warm up. According to the dynamic adjustment of historical forecast error sequence, the terminal - Always awake; Select the data transmission strategy: After waking up, the power management module collects the battery voltage V, samples it 10 times in a row and takes the average value; based on V and the battery full-charge voltage The ratio of transmission mode selection: V ≥ 75% When the original data is sent in full and concatenated with RS (255, 239) + convolutional code with constraint length 7; 25% ≤V<75% When LZ77 algorithm is used to compress data and add shortened Hamming code (7,4); V<25% When sending a 256-byte data summary, it contains a 32-bit timestamp, eight 16-bit parameter extreme values, an 8-bit abnormal flag, and a 16-bit CRC check code. Adjust the data transmission rate: Dynamic energy factor of receiving satellite broadcast every 10 seconds , It is generated by the satellite load rate L and the link signal-to-noise ratio SNR, and the terminal passes = + ・( - )Adjust the transmit power ( =1W, =5W), and adjust the number of data packets sent per time slot; Entering sleep mode: After data transmission is completed, the radio frequency and main control module power supply are turned off, only the low-power RC clock is retained to maintain the RTC timing, and the system enters sleep mode.

[0007] Furthermore, it also includes a low battery emergency mechanism: when V≤15% When the terminal sends the data summary only in the first sub-time slot of the overhead window, it immediately cuts off the power supply of all modules except RTC after the sending is completed, skips the subsequent time slots, and waits until the next window period.

[0008] Furthermore, it also includes dual clock calibration steps: using TCXO high-precision clock and RC low-power clock to work together; turning on TCXO and stabilizing it for 10ms when waking up, and passing the synchronization time after 1 second. =( - )・ Calculate the cumulative error, where is the TCXO timing value, is the RC timing value, =32.768kHz, turn off TCXO after RC clock compensation, and the calibration period is 10 minutes.

[0009] Furthermore, the prediction error compensation The calculation formula is: , where the safety factor μ=1.3, the number of historical error samples n=30, is the k-th prediction error, =e^(-λ(nk)), where the attenuation factor λ=0.4, and the error is dynamically corrected by weighted averaging.

[0010] Furthermore, the generation formula of the dynamic energy factor α is: ; When L=90% or SNR=8dB, =0.2; when L=50% and SNR=25dB, = 1. Furthermore, an environmental compensation step is included: when waking up, the ambient temperature T and the supply voltage V are collected, and the RC clock frequency offset is compensated by bilinear interpolation: in is the distance weight between the current (T, V) and the four neighboring lookup points whose sum is 1, Δf( , ) is the frequency offset value of the lookup point. After compensation, the frequency deviation is ≤±50ppm.

[0011] Furthermore, the RS (255,239) outer code in full transmission mode can correct 8-byte errors, and the convolutional code inner code has an error correction capability of 10% bit errors when the SNR is ≥ 10dB; the LZ77 algorithm in compression mode has a compression rate of ≥ 30%, and the shortened Hamming code (7,4) adds 3 check bits for every 4 bits of data.

[0012] Furthermore, in the terminal self-learning step, the voltage threshold dynamic adjustment formula is: (k+1)= (k)+ ・( (k)- (k)), where the adjustment step size =0.15, (k) is the minimum wake-up voltage value of the last 10 times, updated every 24 hours.

[0013] Furthermore, the data summary adopts TLV format, the transmission time is ≤200ms, the extreme values ​​of key parameters include the maximum / minimum values ​​of temperature and humidity physical quantities, and each bit of the abnormal mark corresponds to a preset abnormal state.

[0014] Furthermore, when calculating the satellite overpass window, the terminal needs to update the ephemeris data through the satellite downlink 24 hours in advance. The ephemeris data is valid for 7 days, and an update should be actively requested 12 hours before expiration to ensure the accuracy of the orbital parameters.

[0015] Compared with the existing technology, the beneficial effects of the present invention are: The low-power data transmission method proposed in this paper significantly improves the performance of low-orbit satellite IoT terminals through multi-dimensional technological innovation. Regarding energy control, a precise wake-up mechanism based on satellite overpass prediction avoids the redundant energy consumption of terminals continuously scanning or blindly waiting. Combined with a hierarchical data transmission strategy, only key summaries are sent and the terminal quickly goes to sleep when the battery is low, significantly extending the terminal's battery life. The dual-clock architecture design balances clock accuracy and power consumption. The high-precision clock is only briefly enabled for calibration during wake-up, while the low-power clock is always resident to maintain timing, effectively reducing the clock system's energy consumption.

[0016] In terms of communication reliability and efficiency, satellite overpass time prediction combined with adaptive compensation for historical errors significantly improves window prediction accuracy, ensuring terminals access the network at the optimal time and increasing communication success rates. A dynamic energy factor adjustment mechanism enables terminals to optimize transmission parameters in real time based on satellite link load and signal-to-noise ratio, reducing congestion and retransmission probability and improving link utilization. A real-time compensation algorithm corrects for the effects of ambient temperature and voltage on the clock, further ensuring the accuracy of the time reference and providing a foundation for precise communication.

[0017] Furthermore, the terminal's self-learning mechanism iteratively optimizes wake-up lead time and transmission strategy parameters, enabling the system to adapt to diverse usage scenarios and environmental changes, continuously improving performance. This overall solution achieves a balance between low power consumption and high reliability, making it particularly suitable for battery- or solar-powered IoT terminals. It offers significant advantages in reducing operational costs and expanding satellite IoT application scenarios. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1This is a schematic block diagram of a low-power data transmission method for low-orbit satellite Internet of Things terminals proposed by the present invention; Figure 2 This is a line graph comparing the satellite overpass time prediction errors; Figure 3 It is a bar graph of transmission energy consumption under different power levels; Figure 4 The scatter plot of time deviation before and after dual clock calibration; Figure 5 A bar chart comparing terminal battery life. DETAILED DESCRIPTION

[0019] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0020] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like to indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0021] In addition, the terms "first" and "second" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the said features. In the description of the present invention, the meaning of "multiple" is two or more, unless otherwise clearly and specifically defined. In addition, the terms "installed", "connected" and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be a connection between the two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances. The present invention will be further described in detail below with reference to the accompanying drawings.

[0022] Reference Figures 1 to 3:A low-power data transmission method for low-orbit satellite Internet of Things terminals, including the following modules: Calculate the satellite overpass time window: Use the satellite ephemeris data containing six Kepler parameters such as orbit semi-major axis, eccentricity, and perigee argument, combined with the geographical location coordinates (lat, lon, positioning accuracy ±3m) obtained by the terminal through the GNSS module, and calculate the satellite and terminal overpass visible time window based on the Kepler orbit equation. , ]. Atmospheric refraction correction is introduced during the calculation process, and the correction amount =0.0015・ ( is the satellite elevation angle, unit: °), ensuring that the window prediction error is ≤±1s; for mobile terminals, the position change correction is calculated based on their movement speed (calculated by GNSS, with an accuracy of ±0.1m / s) =v・ (v is the terminal velocity, is the predicted duration).

[0023] Determine the wake-up lead time: Wake-up lead time Warm-up time of the device and prediction error compensation composition. The fixed value is 100ms, including the RF module phase-locked loop stabilization (30ms) and power amplifier warm-up (70ms); According to the dynamic adjustment of historical forecast error sequence, the terminal - Always awake.

[0024] Select the data transmission strategy: After waking up, the power management module collects the battery voltage V (accuracy ±0.005V) at a sampling frequency of 1kHz, and samples 10 times continuously to get the average value. The ratio of transmission mode selection: V ≥ 75% When the original data is sent in full and RS (255, 239) + convolutional code (constraint length 7) concatenated coding is used; 25% ≤V<75% When using the LZ77 algorithm (sliding window 4KB, dictionary 16KB) to compress data and add a shortened Hamming code (7,4); V < 25% When the data is transmitted, a 256-byte data summary (including a 32-bit timestamp, eight 16-bit parameter extreme values, an 8-bit abnormal flag and a 16-bit CRC check code) is sent.

[0025] Adjust the data transmission rate: Dynamic energy factor of receiving satellite broadcast every 10 seconds , It is generated by the satellite load rate L (0-100%) and the link signal-to-noise ratio SNR (0-30dB), and the terminal passes = + ・( - )Adjust the transmit power ( =1W, =5W), and adjust the number of data packets sent per time slot (1-5 groups).

[0026] Entering sleep mode: After data transmission is completed, the radio frequency and main control module power supply are turned off, and only the low-power RC clock (current ≤ 10μA) is retained to maintain the RTC timing, and then enter the sleep state. The present invention also includes a low-power emergency mechanism: when V ≤ 15% When the terminal sends the data summary only in the first sub-time slot of the overhead window (duration 500ms), it immediately cuts off the power supply of all modules except RTC (current ≤ 5μA) after sending, skips the subsequent time slots, and waits until the next window period (maximum 24h).

[0027] The present invention also includes a dual clock calibration step: using a TCXO high-precision clock (accuracy ±0.5ppm, operating current 5mA) and an RC low-power clock (accuracy ±500ppm, operating current 1μA) to work together. When waking up, the TCXO is turned on and stabilized for 10ms, and the synchronization timing is passed after 1 second. =( - )・ ( is the TCXO timing value, is the RC timing value, =32.768kHz) calculate the cumulative error, compensate the RC clock and turn off the TCXO. The calibration period is 10 minutes.

[0028] In the present invention, the calculation formula of the prediction error compensation amount Δerr is: , where μ=1.3 (safety factor), n=30 (number of historical error samples), is the k-th prediction error, =e^(-λ(nk)) (λ=0.4, attenuation factor), and the error is dynamically corrected by weighted averaging.

[0029] In the present invention, the formula for generating the dynamic energy factor α is: ; When L=90% or SNR=8dB, =0.2; when L=50% and SNR=25dB, = 1. The present invention also includes an environmental compensation step: when waking up, the ambient temperature T (accuracy ±0.1°C) and the power supply voltage V are collected, and the RC clock frequency offset is compensated by bilinear interpolation:

[0030] in is the distance weight between the current (T, V) and the four neighboring lookup points (the sum is 1), Δf( , ) is the frequency offset value of the lookup point (pre-stored in Flash, one point every 0.5℃, 0.1V). After compensation, the frequency deviation is ≤±50ppm.

[0031] In the present invention, the RS (255, 239) outer code in the full transmission mode can correct 8-byte errors, and the convolutional code inner code has an error correction capability of 10% bit errors when the SNR is ≥ 10dB; the LZ77 algorithm in the compression mode has a compression rate of ≥ 30%, and the shortened Hamming code (7, 4) adds 3 check bits for every 4 bits of data.

[0032] The voltage threshold dynamic adjustment formula is: (k+1)= (k)+ ・( (k)- (k)), where =0.15 (adjustment step size), (k) is the minimum wake-up voltage value of the last 10 times, updated every 24 hours.

[0033] In the present invention, the data summary adopts the TLV format, the transmission time is ≤200ms, the extreme values ​​of key parameters include the maximum / minimum values ​​of temperature and humidity physical quantities, and each bit of the abnormal mark corresponds to a preset abnormal state (such as sensor failure, low voltage, etc.).

[0034] In the present invention, when calculating the satellite overpass window, the terminal needs to update the ephemeris data through the satellite downlink 24 hours in advance. The ephemeris data is valid for 7 days, and an active request for update is made 12 hours before expiration to ensure the accuracy of the orbital parameters.

[0035] Example: This method is applicable to low-orbit satellite IoT terminals. The hardware includes a main control module (using an ARM Cortex-M4 core with an 80MHz clock speed), a GNSS module (supporting Beidou / GPS dual-mode and providing a positioning accuracy of ±3m), a power management module (with a voltage sampling accuracy of ±0.005V), a radio frequency module (operating in the 1.2-1.6GHz frequency range and with an adjustable transmit power of 1-5W), a clock module (including a high-precision TCXO clock and a low-power RC clock), memory (4MB Flash + 128KB RAM), and a sensor module. These modules are interconnected via SPI / UART interfaces. The power management module supports multiple power consumption levels, maintaining only the RC clock power supply (current ≤10μA) during sleep mode.

[0036] The satellite over-the-top time window calculation terminal obtains the latitude and longitude (lat, lon) and UTC time through GNSS, and calculates the visible window in combination with the pre-stored satellite ephemeris (including 6 Kepler parameters). , ]. Atmospheric refraction correction is introduced into the calculation: =0.0015・ ( is the satellite elevation angle (unit: °). For example, when the elevation angle is 30°, the correction amount is 0.0013s. After correction, the window error is ≤±1s. The mobile terminal needs to compensate for the position change: =v・ (v is the GNSS solution speed, with an accuracy of ±0.1m / s), ensuring prediction accuracy in vehicle-mounted and ship-mounted scenarios. Ephemeris data is updated every 24 hours via satellite downlink and is valid for 7 days. A refresh request must be made 12 hours before expiration.

[0037] Wake-up Advance and Execution Mechanism Wake-up Advance = + ,in = 100ms (including 30ms for RF PLL stabilization and 70ms for power amplifier warm-up). Δerr is calculated by weighting the historical error: ; Where μ=1.3 (safety factor), n=30 (number of samples), is the kth error, =e^(-0.4(nk)) (attenuation factor 0.4). The terminal is - It is always awakened by the RC clock interrupt, starts the power management module to power each component, and synchronously turns on the TCXO clock (accuracy ±0.5ppm) for calibration.

[0038] After waking up, the power module collects the battery voltage V at a frequency of 1kHz, takes the average value of 10 consecutive samples, and selects the transmission mode proportionally: full mode (V≥75%) ): The original data is cascade-coded with RS (255,239) outer code (correcting 8 byte errors) + convolutional code (constraint length 7), ensuring an error correction capability of 10% bit error when SNR ≥ 10dB. Compression mode (25% ≤ <75% :Use LZ77 algorithm for compression (4KB sliding window, 16KB dictionary, compression rate ≥ 30%), add shortened Hamming code (7,4), and attach 3 check bits for every 4 bits of data. Summary mode ( <25% ): Send a 256-byte TLV format summary, including a 32-bit timestamp, 8 16-bit parameter extreme values ​​(such as the maximum temperature and humidity), an 8-bit abnormality flag (each bit corresponds to a preset fault) and a 16-bit CRC check code. The transmission time is ≤ 200ms. Low battery emergency mechanism ( ≤15% ): The summary is sent only in the first 500ms sub-time slot of the window, and then all power supplies except the RTC are cut off (current ≤ 5μA) until the next window period (maximum 24h).

[0039] Dynamic link adaptation and clock calibration The satellite broadcasts a dynamic energy factor α every 10 seconds, which is generated by the onboard load L and the signal-to-noise ratio SNR: ; Terminal Press =1+ ・4 Adjust the transmit power (in W) and the number of packets per time slot (1-5 groups). For example, when L=90%, α=0.2, transmit power 1.8W, and send 1 group of data per time slot; when SNR=25dB and L=50%, α=1, power 5W, and send 5 groups of data. Clock calibration uses dual clock coordination: when waking up, TCXO starts and stabilizes for 10ms, and then =( - )・32768Calculate RC clock error( Clocking the TCXO, = RC timing (unit: s) and then turn off the TCXO after compensation. Combined with environmental compensation: collect temperature T (±0.1°C) and voltage V, and use bilinear interpolation to calculate: ; ( is the distance weight, The RC frequency deviation is controlled within ±50ppm, and the calibration period is 10 minutes.

[0040] The terminal self-learning optimization terminal records the time slot error, success rate and voltage curve of each communication, and updates the model every 10 communication iterations: Voltage threshold adjustment: (k+1)= (k)+0.15・( (k)- (k)), (k) is the minimum value of the wake-up voltage in the last 10 times, updated every 24 hours. Dynamic correction of the attenuation factor λ: when the error increases, λ is reduced to 0.3, and maintained at 0.4 when stable, improving Computational adaptability.

[0041] Effect data representation and interpretation

[0042] The above data is based on comparative testing of terminals with 3000mAh lithium batteries. The extended battery life is attributed to precise wakeup (reducing idle power consumption by 90%) and hierarchical transmission (reducing power consumption to 16% at low battery levels). Access success rates are improved thanks to error compensation and clock calibration, ensuring accurate terminal activation within the activation window. Dynamic power adjustment reduces single-transmission energy consumption by 76%, while environmental compensation and self-learning mechanisms control timing errors to within 1 second, reducing the failure rate to 3%. The overall solution achieves a balance between low power consumption and high reliability, making it suitable for all types of battery-powered satellite IoT terminals.

[0043] The above are only preferred specific embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any technician familiar with this technical field, within the technical scope disclosed by the present invention, who makes equivalent replacements or changes based on the technical solutions and inventive concepts of the present invention, should be covered by the scope of protection of the present invention.

Claims

1. A low-power data transmission method for low-orbit satellite Internet of Things terminals, characterized in that: The following steps are involved: Calculate the satellite overpass time window: Use satellite ephemeris data, combined with the geographical location coordinates obtained by the terminal through the GNSS module, and calculate the satellite and terminal overpass visible time window based on the Kepler orbit equation. , ]; Atmospheric refraction correction is introduced during the calculation process, and the correction amount =0.0015・ ,in is the satellite elevation angle; for mobile terminals, the position change correction is calculated based on its movement speed =v・ , where v is the terminal velocity, is the predicted duration; Determine the wake-up lead time: Wake-up lead time Warm-up time of the device and prediction error compensation composition; The fixed value is 100ms, including 30ms for the RF module phase-locked loop to stabilize and 70ms for the power amplifier to warm up. According to the dynamic adjustment of historical forecast error sequence, the terminal - Always awake; Select the data transmission strategy: After waking up, the power management module collects the battery voltage V, samples it 10 times in a row and takes the average value; based on V and the battery full-charge voltage The ratio of transmission mode selection: V ≥ 75% When the original data is sent in full and concatenated with RS (255, 239) + convolutional code with constraint length 7; 25% ≤V<75% When LZ77 algorithm is used to compress data and add shortened Hamming code (7,4); V<25% When sending a 256-byte data summary, it contains a 32-bit timestamp, eight 16-bit parameter extreme values, an 8-bit abnormal flag, and a 16-bit CRC check code. Adjust the data transmission rate: Dynamic energy factor of receiving satellite broadcast every 10 seconds , It is generated by the satellite load rate L and the link signal-to-noise ratio SNR, and the terminal passes = + ・( - )Adjust the transmit power ( =1W, =5W), and adjust the number of data packets sent per time slot; Entering sleep mode: After data transmission is completed, the radio frequency and main control module power supply are turned off, only the low-power RC clock is retained to maintain the RTC timing, and the system enters sleep mode.

2. A low-power data transmission method for low-orbit satellite Internet of Things terminals according to claim 1, characterized in that: It also includes a low battery emergency mechanism: when V≤15% When the terminal sends the data summary only in the first sub-time slot of the overhead window, it immediately cuts off the power supply of all modules except RTC after the sending is completed, skips the subsequent time slots, and waits until the next window period.

3. The low-power data transmission method for low-orbit satellite Internet of Things terminals according to claim 1, characterized in that: It also includes dual clock calibration steps: using TCXO high-precision clock and RC low-power clock to work together; turning on TCXO and stabilizing it for 10ms when waking up, and passing the synchronization time after 1 second =( - )・ Calculate the cumulative error, where is the TCXO timing value, is the RC timing value, =32.768kHz, turn off TCXO after RC clock compensation, and the calibration period is 10 minutes.

4. The low-power data transmission method for low-orbit satellite Internet of Things terminals according to claim 1, characterized in that: Prediction error compensation The calculation formula is: , where the safety factor μ=1.3, the number of historical error samples n=30, is the k-th prediction error, =e^(-λ(nk)), where the attenuation factor λ=0.4, and the error is dynamically corrected by weighted averaging.

5. The low-power data transmission method for low-orbit satellite Internet of Things terminals according to claim 1, characterized in that: The generation formula of dynamic energy factor α is: ； When L=90% or SNR=8dB, =0.2; when L=50% and SNR=25dB, =1.

6. The low-power data transmission method for low-orbit satellite Internet of Things terminals according to claim 3, characterized in that: It also includes an environmental compensation step: when waking up, the ambient temperature T and the supply voltage V are collected, and the RC clock frequency offset is compensated by bilinear interpolation: ; in is the distance weight between the current (T, V) and the four neighboring lookup points whose sum is 1, Δf( , ) is the frequency offset value of the lookup point. After compensation, the frequency deviation is ≤±50ppm.

7. The low-power data transmission method for low-orbit satellite Internet of Things terminals according to claim 1, characterized in that: The RS (255,239) outer code in full transmission mode can correct 8-byte errors, and the convolutional code inner code has an error correction capability of 10% bit errors when the SNR is ≥ 10dB. The LZ77 algorithm in compression mode has a compression rate of ≥ 30%, and the shortened Hamming code (7,4) adds 3 check bits for every 4 bits of data.

8. The low-power data transmission method for low-orbit satellite Internet of Things terminals according to claim 1, characterized in that: In the terminal self-learning step, the voltage threshold dynamic adjustment formula is: (k+1)= (k)+ ・( (k)- (k)), where the adjustment step size =0.15, (k) is the minimum value of the wake-up voltage in the last 10 times.

9. The low-power data transmission method for low-orbit satellite Internet of Things terminals according to claim 1, characterized in that: The data summary uses the TLV format, and the transmission time is ≤200ms. The extreme values ​​of key parameters include the maximum / minimum values ​​of the physical quantities of temperature and humidity. Each bit of the abnormal mark corresponds to a preset abnormal state.

10. The low-power data transmission method for low-orbit satellite Internet of Things terminals according to claim 1, characterized in that: When calculating the satellite over-the-top window, the terminal needs to update the ephemeris data through the satellite downlink 24 hours in advance. The ephemeris data is valid for 7 days and an update request should be made 12 hours before the expiration date.

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