Emergency communication methods, equipment and systems based on low-Earth orbit satellite networks

Abstract

This application relates to the field of network communication transmission technology, specifically to an emergency communication method, device, and system based on low-Earth orbit (LEO) satellite networks. The method includes: dividing each communication bit sequence into multiple sub-sequences by analyzing whether the two consecutive bits following each bit with a value of 1 are 0; determining the information distribution disorder by analyzing the differences between all sub-sequences of each communication bit sequence and combining the irregularity of the information arrangement of the corresponding position sequences of each communication bit sequence, thereby determining the encoding length of each communication bit sequence; and conducting emergency communication via a LEO satellite network based on each communication bit sequence and its encoding length. This application solves the problem that fixed-length LDPC codes cannot accurately correct errors in high-information-entropy communication data, improving the communication transmission efficiency and data integrity of LEO satellites in disaster areas.

Description

Technical Field

[0001] This application relates to the field of network communication transmission technology, specifically to emergency communication methods, equipment, and systems based on low-Earth orbit satellite networks. Background Technology

[0002] Low Earth Orbit (LEO) satellite networks are communication systems built using constellations of satellites operating in low Earth orbit (altitude 500-2000 kilometers). LEO satellite networks achieve seamless global coverage through the coordinated networking of multiple satellites, featuring low latency, high reliability, and large capacity. In disaster emergency communications, LEO satellite networks can quickly restore communication. Unaffected by ground infrastructure, LEO satellite networks can rapidly provide stable voice, data, and video communication services even when ground communications are disrupted by natural disasters such as earthquakes and floods. In remote areas or severely affected regions, LEO satellite networks can build a reliable communication bridge between rescue teams, affected populations, and command centers, ensuring timely information transmission and efficient rescue operations.

[0003] When conducting network communication in disaster areas, checksums are typically added to the communication data to prevent errors caused by electromagnetic interference and ensure data integrity. Traditional low-Earth orbit (LEO) satellites usually add fixed-length LDPC codes to the communication data for correction; however, for data with high complexity and high information entropy, the error correction capability of fixed-length LDPC codes is insufficient. This makes it impossible to accurately correct errors in high-information-entropy communication data, leading to reduced communication transmission efficiency and data integrity of LEO satellites in disaster areas. Summary of the Invention

[0004] In a first aspect, embodiments of this application provide an emergency communication method based on a low-Earth orbit satellite network, the method comprising the following steps:

[0005] The ground station acquires the communication data that needs to be transmitted by the low-orbit satellite and converts the communication data into a binary bit stream, which is then divided into multiple communication bit sequences.

[0006] All bit values ​​in each communication bit sequence are numbered in position order. All bit values ​​of 1 are combined into a position sequence. By analyzing the extreme value distribution and dispersion of all elements in the first-order difference sequence of the position sequence, the bit spacing difference of the position sequence is determined.

[0007] Data with a value of 1 in the first-order difference sequence of the position sequence are removed to obtain the interval distribution sequence. Based on the complexity of all elements in the interval distribution sequence, and combined with the number of all elements with a value of 1 in the first-order difference sequence of the position sequence and the bit spacing difference, the irregularity of the information arrangement of the position sequence is determined.

[0008] By analyzing whether the two consecutive bits following each bit with a value of 1 in each communication bit sequence are 0, each communication bit sequence is divided into multiple subsequences; by analyzing the differences between all subsequences of each communication bit sequence, the difference characteristic value of each communication bit sequence is determined; and by combining the irregularity of the information arrangement of the corresponding position sequence of each communication bit sequence, the information distribution disorder of each communication bit sequence is determined.

[0009] Based on the aforementioned information distribution disorder, the encoding length of each communication bit sequence is determined; emergency communication of the low-Earth orbit satellite network is then conducted based on each communication bit sequence and its encoding length.

[0010] Preferably, the bit spacing difference of the position sequence is the result of positive fusion of the range and standard deviation of all elements in the first-order difference sequence of the position sequence.

[0011] Preferably, the expression for the irregularity of the information arrangement of the position sequence is: In the formula, This indicates the irregularity of the arrangement of information in a positional sequence; This represents the complexity of all elements in the interval distribution sequence corresponding to the position sequence; This represents the number of all elements with a value of 1 in the first-order difference sequence of the position sequence; Indicates the bit spacing difference in the position sequence; This indicates a constant that is preset to be greater than 0.

[0012] Preferably, dividing each communication bit sequence into multiple sub-sequences includes:

[0013] In each communication bit sequence, starting from the first bit with a value of 1, if any bit value in the next adjacent bit and the second adjacent bit of the first bit with a value of 1 is not 0, then the next adjacent bit value is added to the current subsequence. The operation of the first bit value of 1 is repeated for the next adjacent bit value. It is determined whether any bit value in the two consecutive bits after the next adjacent bit value is not 0. The above iterative process is repeated until the two consecutive bits after a bit are both 0, thus completing the division of the current subsequence.

[0014] In the remaining bits of each communication bit sequence, the first bit with a value of 1 is taken as the new starting point, and the process of dividing the current subsequence is repeated to obtain a new subsequence. The above subsequence division process is repeated until the remaining bits of each communication bit sequence no longer contain a bit with a value of 1, thus completing the subsequence division.

[0015] Preferably, the difference characteristic value of each communication bit sequence is the mean of the differences between all subsequences of each communication bit sequence.

[0016] Preferably, the information distribution disorder of each communication bit sequence is the product of the information arrangement irregularity of the corresponding position sequence of each communication bit sequence and the corresponding difference feature value.

[0017] Preferably, the expression for the encoding length of each communication bit sequence is: In the formula, Indicates the encoded length of the communication bit sequence i; , These represent 1 / 4 and 1 / 2 of the length of the communication bit sequence i, respectively; , These represent the minimum and maximum values ​​of the disorder in the distribution of all communication bit sequences in the binary bit stream of communication data transmitted by low-Earth orbit satellites, respectively.

[0018] Preferably, the emergency communication of the low-Earth orbit satellite network based on each communication bit sequence and its encoding length includes:

[0019] Each communication bit sequence and its encoding length are used as input to LDPC encoding technology, and the LDPC code of each communication bit sequence is output. The communication bit sequences and their LDPC codes are concatenated and encapsulated into frame data, and all frame data are transmitted to the low-Earth orbit satellite network for emergency communication.

[0020] Secondly, embodiments of this application also provide an emergency communication device based on a low-Earth orbit satellite network, wherein the device stores a computer program, and when the computer program is executed by a processor, it implements the emergency communication method based on a low-Earth orbit satellite network described above.

[0021] Thirdly, embodiments of this application provide an emergency communication system based on a low-Earth orbit satellite network, including a memory, a processor, and a computer program stored in the memory and running on the processor. When the processor executes the computer program, it implements any of the above-described emergency communication methods based on a low-Earth orbit satellite network.

[0022] As can be seen from the above embodiments, the emergency communication method based on low-Earth orbit satellite networks provided in this application has at least the following beneficial effects:

[0023] This application constructs a bit spacing difference degree by analyzing the regularity of the occurrence positions of bits with a value of 1 in communication data. Based on the bit spacing difference degree, an appropriate LDPC code length can be dynamically selected for subsequent communication data encoding, thereby optimizing encoding efficiency while ensuring data transmission quality. Furthermore, this application constructs an information arrangement irregularity degree by analyzing the distribution regularity of bits with a value of 1 in communication data, quantifying the degree of irregularity in the arrangement of communication data information, thereby dynamically selecting the LDPC code length and improving communication transmission efficiency and data integrity in disaster area communications. Furthermore, this application constructs an information distribution disorder degree by analyzing the distribution regularity of bits with a value of 1 in communication data and combining it with the information arrangement irregularity degree, dynamically adjusting the LDPC code length. When the data regularity is strong, a short code is used to improve efficiency, and when the regularity is poor, a long code is used to enhance error correction. Thus, in low-Earth orbit satellite emergency communications, both the reliability of data transmission and the optimization of valuable bandwidth resources are ensured, improving the communication transmission efficiency and data integrity of low-Earth orbit satellites in disaster area communications. Attached Figure Description

[0024] To more clearly illustrate the technical solutions and advantages in the embodiments of this application or the prior art, 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.

[0025] Figure 1 A flowchart illustrating the steps of an emergency communication method based on a low-Earth orbit satellite network provided in one embodiment of this application;

[0026] Figure 2 This is a schematic diagram illustrating the process of obtaining the disorder of information distribution as provided in one embodiment of this application. Detailed Implementation

[0027] To further illustrate the technical means and effects adopted by this application to achieve the intended purpose of the invention, the following, in conjunction with the accompanying drawings and preferred embodiments, details the specific implementation methods, structures, features, and effects of the emergency communication method, device, and system based on low-Earth orbit satellite networks proposed in this application. In the following description, different "one embodiment" or "another embodiment" do not necessarily refer to the same embodiment. Furthermore, specific features, structures, or characteristics in one or more embodiments can be combined in any suitable form.

[0028] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0029] The following description, in conjunction with the accompanying drawings, details the specific solutions for the emergency communication methods, equipment, and systems based on low-Earth orbit satellite networks provided in this application.

[0030] Please see Figure 1 The diagram illustrates a flowchart of an emergency communication method based on a low-Earth orbit satellite network according to an embodiment of this application. The method includes the following steps:

[0031] S1: Obtain the communication data that needs to be transmitted by the low-orbit satellite through the ground station and convert the communication data into a binary bit stream, and divide the binary bit stream into multiple communication bit sequences.

[0032] First, the ground station acquires the communication data that needs to be transmitted by the low-Earth orbit satellite. After acquiring the data, it converts it into a binary bit stream using UTF-8 character encoding. Further, to adapt to the specific requirements of the satellite communication link and optimize transmission efficiency, the ground station segments the binary bit stream. Specifically, it segments the binary bit stream into multiple communication bit sequences, each containing 512 bits. The last bit of the binary bit stream that is shorter than 512 bits also forms a communication bit sequence.

[0033] S2: By analyzing the complexity and regularity of communication data, determine the degree of disorder in the information distribution of each communication bit sequence.

[0034] While low-Earth orbit (LEO) satellite networks offer low latency and high reliability, during disasters, the communication link between the ground and satellites is often subject to strong electromagnetic interference, leading to signal distortion and even data loss. This severely impacts the accurate transmission of critical information such as voice, data, and video, hindering effective rescue efforts. LDPC (Low-Density Parity-Check) codes, as an efficient error correction coding technique, can detect and correct erroneous bits generated during transmission at the receiving end.

[0035] However, traditional LDPC coding cannot flexibly adjust the error correction protection level according to the actual complexity and regularity of the communication data. That is, for data with high complexity and high information entropy, the error correction capability of fixed-length LDPC codes is insufficient, making it impossible to accurately correct errors in high information entropy communication data, resulting in reduced integrity and efficiency of communication data. Therefore, this embodiment analyzes the complexity and regularity of communication data and dynamically adjusts the coding length to improve the integrity and efficiency of communication data. The dynamic adjustment process of LDPC coding length is as follows:

[0036] S201: By numbering the bits with a value of 1 in each communication bit sequence according to their position, and forming a position sequence from all the numbers, the bit spacing difference of the position sequence is determined by analyzing the extreme value distribution and dispersion of all elements in the first-order difference sequence of the position sequence.

[0037] When calculating LDPC check codes for transmitted communication data, if the communication information bits exhibit high regularity, it indicates the presence of a pattern or repetitive structure in the data. In such cases, the number of check bits can be appropriately reduced to improve coding efficiency. Since bit data consists only of 0s and 1s, a large number of 1s indicates that the communication data carries a significant amount of valid information. Therefore, in this embodiment, the bits with a value of 1 in each communication bit sequence are numbered sequentially according to their positions, and all these numbers are combined to form a position sequence. By analyzing the extreme value distribution and dispersion of all elements in the first-order difference sequence of the position sequence, the bit spacing difference of the position sequence is determined to reflect the regularity and predictability of the data corresponding to each communication bit sequence. Specifically:

[0038] First, number all bit values ​​in each communication bit sequence according to their position, and form a position sequence by combining all bit values ​​of 1.

[0039] Furthermore, the more regularly 1d bits appear, the higher the predictability of the communication data, and the less need for long LDPC codes to correct errors. Therefore, this embodiment determines the bit spacing difference of the position sequence by analyzing the extreme value distribution and dispersion of all elements in the first-order difference sequence of the position sequence. Specifically:

[0040] In this embodiment, the result of positively fusing the range and standard deviation of all elements in the first-order difference sequence of the position sequence is used as the bit spacing difference of the position sequence.

[0041] It should be understood that positive fusion refers to combining two or more indicators through addition or multiplication to obtain a comprehensive indicator, thereby more comprehensively and accurately assessing a phenomenon or problem. This fusion method is not limited to simple arithmetic operations, but can also include more complex statistical models and analytical methods. Implementers can choose according to specific circumstances, and this embodiment does not impose any special restrictions.

[0042] Therefore, as a specific implementation method, in this embodiment, the product of the range and standard deviation of all elements in the first-order difference sequence of the position sequence is used as the bit spacing difference of the position sequence.

[0043] Based on the bit spacing difference of the position sequence, it can be understood that the smaller the range of all elements in the first-order difference sequence of the position sequence, the smaller the range of the interval variation between bits with a value of 1. That is, the bits with a value of 1 are distributed very evenly in the communication bit sequence and have strong consistency. Therefore, the smaller the bit spacing difference of the corresponding position sequence, the more obvious the regularity or pattern of the position of bits with a value of 1 in the communication bit sequence. At this time, a shorter LDPC code can be used to correct errors in the communication data. At the same time, the smaller the standard deviation of all elements in the first-order difference sequence of the position sequence, the more evenly and regularly the interval distribution between bits with a value of 1 is, and the corresponding bit spacing difference is also relatively small.

[0044] Conversely, if the range of all elements in the first-order difference sequence of the position sequence is larger, it indicates that the interval between bits with a value of 1 varies greatly. This means that the distribution of bits with a value of 1 in the communication bit sequence is very uneven and lacks consistency, i.e., this distribution exhibits obvious randomness. Therefore, the greater the difference in bit spacing in the corresponding position sequence, the more irregular the position of bits with a value of 1 appears in the communication bit sequence. In this case, using a shorter LDPC code may not be sufficient to provide enough error correction capability to deal with possible transmission errors. Therefore, a longer LDPC code needs to be selected to enhance error correction capability and ensure data reliability. At the same time, if the standard deviation of all elements in the first-order difference sequence of the position sequence is larger, it indicates that the distribution of bits with a value of 1 in the communication bit sequence lacks regularity. Therefore, the corresponding difference in bit spacing is also relatively large. This also indicates that the position of bit 1 in the data lacks obvious regularity or pattern, requiring stronger error correction protection. Therefore, a longer LDPC code also needs to be selected for error correction.

[0045] Thus, this embodiment constructs a bit spacing difference degree by analyzing the regularity of the positions of bits with a value of 1 in the communication data. Based on the bit spacing difference degree, an LDPC code of appropriate length can be dynamically selected for subsequent communication data encoding, thereby optimizing encoding efficiency while ensuring data transmission quality.

[0046] S202: Remove data with a value of 1 from the first-order difference sequence of the position sequence to obtain the interval distribution sequence. Based on the complexity of all elements in the interval distribution sequence, and combined with the number of all elements with a value of 1 in the first-order difference sequence of the position sequence and the bit spacing difference, determine the irregularity of the information arrangement of the position sequence.

[0047] In information transmission in disaster areas, communication conditions can be extremely harsh, with strong signal interference and unstable transmission. Therefore, while ensuring the integrity of the information content, the length of transmitted data should be compressed as much as possible. Reducing data redundancy not only improves transmission efficiency and lowers the fault tolerance rate, but also allows more critical information to be transmitted within limited bandwidth and time. Therefore, when the element value of a position sequence is 1 in the first-order difference sequence, it indicates that the bits with a value of 1 in the communication bit sequence are adjacent bits. The more times the data with a value of 1 appears in the first-order difference sequence, the higher the repetition structure of the communication data, which indicates that the communication data has a high degree of regularity and predictability. Shorter LDPC codes can be used to correct the data.

[0048] Therefore, based on the above analysis, this embodiment obtains an interval distribution sequence by removing data with an element value of 1 from the first-order difference sequence of the position sequence. Based on the complexity of all elements in the interval distribution sequence, and combined with the number of all elements with an element value of 1 in the first-order difference sequence of the position sequence and the bit spacing difference, the irregularity of the information arrangement of the position sequence is determined to reflect the randomness of the information distribution in the communication data. Specifically:

[0049] In this embodiment, firstly, data with an element value of 1 in the first-order difference sequence of the position sequence are removed to obtain an interval distribution sequence, which is used to characterize whether the distribution of bits with a bit value of 1 in non-adjacent positions exhibits regularity.

[0050] Furthermore, this embodiment determines the irregularity of the information arrangement of the position sequence based on the complexity of all elements in the interval distribution sequence, combined with the number of all elements with a value of 1 in the first-order difference sequence of the position sequence and the bit spacing difference, specifically as follows:

[0051] As one implementation method, in this embodiment, the expression for the irregularity of the information arrangement of the position sequence is: In the formula, This indicates the irregularity of the arrangement of information in a positional sequence; This represents the complexity of all elements in the interval distribution sequence corresponding to the position sequence; This represents the number of all elements with a value of 1 in the first-order difference sequence of the position sequence; Indicates the bit spacing difference in the position sequence; This represents a preset constant greater than 0, used to prevent the denominator from being 0. In this embodiment... The value is set manually, in this embodiment. The value of is 0.01. Provided that the denominator is not zero and does not excessively affect the calculation result, the implementer may also set it according to the specific situation. This embodiment does not impose any special restrictions.

[0052] It should be noted that there are many ways to measure the complexity of a set of data. In this embodiment, the Lempel-Ziv complexity of all elements in the interval distribution sequence corresponding to the position sequence is taken as the complexity of all elements in the interval distribution sequence corresponding to the position sequence. In practical applications, as other implementation methods, implementers may also use other methods such as information entropy to measure data complexity in combination with specific circumstances. This embodiment does not impose any special restrictions on the selection of methods for measuring data complexity.

[0053] The method for calculating Lempel-Ziv complexity is a well-known technique, and its specific calculation process will not be elaborated here.

[0054] Based on the irregularity of the information arrangement in the position sequence, we can understand that if the complexity of all elements in the interval distribution sequence corresponding to the position sequence is greater, it indicates that the distribution pattern of the number of bits with a value of 1 being greater than 1 is more complex and random. This means that the corresponding communication bit sequence contains more different and non-repeating interval patterns, and the overall distribution is more disordered. Therefore, the corresponding information arrangement irregularity is greater. At the same time, if the number of elements with a value of 1 in the first-order difference sequence of the position sequence is smaller, it reflects that the bits with a value of 1 rarely appear consecutively in the communication bit sequence. This indicates that the distribution of bits with a value of 1 in the communication bit sequence is more irregular. Therefore, the corresponding information arrangement irregularity is greater. In addition, if the difference in the bit spacing of the position sequence is greater, it means that the interval between bits with a value of 1 in the communication bit sequence is more dispersed, and the overall distribution is more volatile. This increases the irregularity of the distribution of bits with a value of 1 in the communication bit sequence. Thus, the corresponding information arrangement irregularity is greater. Therefore, a longer LDPC code needs to be selected for error correction to ensure the integrity of the communication data.

[0055] Conversely, the smaller the complexity of all elements in the interval distribution sequence corresponding to the position sequence, the simpler and more regular the distribution pattern of the number of bits with a value of 1 being greater than 1. This indicates that there are fewer different and non-repeating interval patterns in the corresponding communication bit sequence, and the overall distribution is more ordered. Therefore, the irregularity of the corresponding information arrangement is smaller. At the same time, the more elements with a value of 1 in the first-order difference sequence of the position sequence, the more frequently the bits with a value of 1 appear consecutively in the communication bit sequence. This indicates that the distribution of bits with a value of 1 in the communication bit sequence is more regular. Therefore, the irregularity of the corresponding information arrangement is smaller. In addition, the smaller the difference in the bit spacing of the position sequence, the more uniform and concentrated the intervals between bits with a value of 1 in the communication bit sequence are, and the lower the fluctuation of the overall distribution. This makes the distribution of bits with a value of 1 in the communication bit sequence more regular. Thus, the irregularity of the corresponding information arrangement is smaller. Therefore, a shorter LDPC code can be selected to reduce coding redundancy and improve transmission efficiency.

[0056] Thus, this embodiment constructs the information arrangement irregularity by analyzing the distribution regularity of bits with a value of 1, quantifies the degree of irregularity in the arrangement of communication data information, and dynamically selects the LDPC code length, thereby improving the communication transmission efficiency and data integrity in disaster area communications.

[0057] S203: By analyzing whether the two consecutive bits following each bit with a value of 1 in each communication bit sequence are 0, each communication bit sequence is divided into multiple subsequences; by analyzing the differences between all subsequences of each communication bit sequence, the difference characteristic value of each communication bit sequence is determined, and the information distribution disorder of each communication bit sequence is determined by combining the information arrangement irregularity of the corresponding position sequence of each communication bit sequence.

[0058] For communication bit sequences, higher continuity of communication data indicates more regular data changes. However, since the binary data corresponding to communication characters are not the same, and the data corresponding to the binary "11111111" is an invalid byte sequence that does not correspond to a valid character, there must be a bit 0 in the binary data during communication. Therefore, this embodiment analyzes whether the two consecutive bits following each bit with a value of 1 in each communication bit sequence are 0, in order to divide each communication bit sequence into multiple subsequences. Specifically:

[0059] In each communication bit sequence, starting from the first bit with a value of 1, if any bit value in the next adjacent bit and the second adjacent bit of the first bit with a value of 1 is not 0, then the next adjacent bit value is added to the current subsequence. The operation of the first bit value of 1 is repeated for the next adjacent bit value. It is determined whether any bit value in the two consecutive bits after the next adjacent bit value is not 0. The above iterative process is repeated until the two consecutive bits after a bit are both 0, thus completing the division of the current subsequence.

[0060] In the remaining bits of each communication bit sequence, the first bit with a value of 1 is taken as the new starting point, and the process of dividing the current subsequence is repeated to obtain a new subsequence. The above subsequence division process is repeated until the remaining bits of each communication bit sequence no longer contain a bit with a value of 1, thus completing the subsequence division.

[0061] To facilitate understanding of the above process, a specific example is given, such as: Suppose the communication bit sequence is "001011010111010010100", which, after being split, yields two subsequences: "101101011101" and "101".

[0062] The more similar the segmented subsequences are, the more regular and predictable the binary data distribution of the communication data is. Therefore, this embodiment analyzes the differences between all subsequences of each communication bit sequence to determine the difference characteristic value of each communication bit sequence, and combines this with the irregularity of the information arrangement of the corresponding position sequences of each communication bit sequence to determine the information distribution disorder of each communication bit sequence, specifically:

[0063] In this embodiment, the mean of the differences between all subsequences of each communication bit sequence is used as the difference feature value of each communication bit sequence to characterize the degree of difference between the subsequences.

[0064] It should be noted that there are many methods to measure the degree of difference between sequences. In this embodiment, the Levenshtein distance between all subsequences of each communication bit sequence is taken as the difference between all subsequences of each communication bit sequence. In practical applications, as other implementation methods, implementers may also use other methods such as DTW distance to measure the difference between sequences in combination with specific circumstances. This embodiment does not impose any special restrictions on the selection of methods to measure the difference between sequences.

[0065] The method for calculating the Levenshtein distance is a well-known technique, and its specific calculation process will not be elaborated here.

[0066] Furthermore, this embodiment determines the information distribution disorder of each communication bit sequence by combining the difference feature values ​​of each communication bit sequence with the information arrangement irregularity of the corresponding position sequence of each communication bit sequence, specifically as follows:

[0067] In this embodiment, the product of the irregularity of the information arrangement of the corresponding position sequence of each communication bit sequence and the corresponding difference feature value is used as the information distribution disorder of each communication bit sequence.

[0068] Preferably, the schematic diagram of the information distribution disorder acquisition process provided in this embodiment is as follows: Figure 2 As shown.

[0069] Based on the information distribution disorder of each communication bit sequence, it can be understood that the larger the difference characteristic value of the current communication bit sequence, the greater the pattern difference between the various sub-sequences obtained after the communication bit sequence is divided. This indicates that the overall communication data has poor structure and regularity, and is in a high state of disorder. Therefore, the greater the information distribution disorder, the lower the predictability of the communication data. At the same time, the greater the information arrangement irregularity of the current communication bit sequence, the more irregular the distribution of bits with a value of 1 in the communication bit sequence is. This indicates that the original communication data has poor regularity, and the corresponding information distribution disorder is also greater. Therefore, it is necessary to increase the length of the LDPC code to ensure the integrity of the communication data.

[0070] Conversely, the smaller the difference characteristic value of the current communication bit sequence, the smaller the pattern difference between the various sub-sequences obtained after the communication bit sequence is divided. This indicates that the overall communication data has a better structure and regularity, exhibiting a lower degree of disorder. Therefore, the smaller the disorder of the corresponding information distribution, the higher the predictability of the communication data. At the same time, the smaller the irregularity of the information arrangement of the current communication bit sequence, the more regular the distribution of bits with a value of 1 in the communication bit sequence is. This indicates that the original communication data has a better regularity, and the corresponding disorder of the information distribution is also smaller. Therefore, the length of the LDPC code can be appropriately reduced. While ensuring basic error correction capability, coding redundancy can be reduced, transmission efficiency can be improved, and the valuable low-orbit satellite communication bandwidth can be utilized more effectively, especially in emergency communication scenarios with high timeliness requirements.

[0071] Thus, this embodiment segments the data by analyzing the pattern of consecutive bits after the bit value of 1, compares the differences between subsequences and the regularity of the distribution of bits with a bit value of 1, quantifies the information disorder, selects long LDPC codes to enhance error correction when the disorder is high, and selects short codes to improve efficiency when the disorder is low, thereby ensuring the reliability of communication data and improving communication efficiency.

[0072] S3: Based on the information distribution disorder, determine the encoding length of each communication bit sequence; based on each communication bit sequence and its encoding length, conduct emergency communication for the low-Earth orbit satellite network.

[0073] Through the above steps, the information distribution disorder of each communication bit sequence is calculated. Based on the information distribution disorder, the encoding length of each communication bit sequence is determined. Emergency communication of the low-Earth orbit satellite network is then performed based on each communication bit sequence and its encoding length. Specifically:

[0074] In this embodiment, the encoding length of the communication bit sequence i is... The expression is: In the formula, , These represent 1 / 4 and 1 / 2 of the length of the communication bit sequence i, respectively; , These represent the minimum and maximum values ​​of the disorder in the distribution of all communication bit sequences in the binary bit stream of communication data transmitted by low-Earth orbit satellites, respectively.

[0075] It should be noted that, since the communication bit sequence consists of 512 bits, therefore, , The values ​​are 128 and 256, respectively.

[0076] Furthermore, each communication bit sequence and its encoding length are used as input to LDPC encoding technology, and the LDPC codes of each communication bit sequence are output. The communication bit sequences and their LDPC codes are concatenated and encapsulated into frame data. The ground station transmits all frame data to the low-Earth orbit satellite network via wireless transmission technology. The low-Earth orbit satellite network uses wavenumber shaping technology to modulate all frame data onto radio carriers to form radio signals, and concentrates the radio signals in a specific direction in the disaster area. The radio signals are then transmitted through frequency hopping spread spectrum technology to achieve emergency communication to the disaster area.

[0077] Among them, beamforming technology and frequency hopping spread spectrum technology are well-known technologies, and their specific principles and processes will not be elaborated here.

[0078] Thus, this embodiment analyzes the distribution regularity of bits with a value of 1 in the communication data, calculates the information distribution disorder, and dynamically adjusts the LDPC code length. When the data regularity is strong, short codes are used to improve efficiency, and when the regularity is poor, long codes are used to enhance error correction. In this way, in low-orbit satellite emergency communication, the reliability of data transmission is guaranteed, valuable bandwidth resources are optimized, and transmission efficiency is improved.

[0079] Based on the same inventive concept as the above methods, embodiments of this application also provide an emergency communication device based on a low-Earth orbit satellite network. The device stores a computer program, which, when executed by a processor, implements the emergency communication method based on a low-Earth orbit satellite network described above.

[0080] Based on the same inventive concept as the above methods, this application also provides an emergency communication system based on a low-Earth orbit satellite network, including a memory, a processor, and a computer program stored in the memory and running on the processor. When the processor executes the computer program, it implements the steps of any one of the above-described emergency communication methods based on a low-Earth orbit satellite network.

[0081] It should be noted that the order of the embodiments described above is merely for descriptive purposes and does not represent the superiority or inferiority of the embodiments. Furthermore, specific embodiments of this specification have been described above. Additionally, the processes depicted in the accompanying drawings do not necessarily require a specific or sequential order to achieve the desired results. In some implementations, multitasking and parallel processing are possible or may be advantageous.

[0082] The various embodiments in this specification are described in a progressive manner. The same or similar parts between the various embodiments can be referred to each other. Each embodiment focuses on describing the differences from other embodiments.

[0083] The above description is only a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, improvements, etc., made within the principles of this application should be included within the protection scope of this application.

Claims

1. An emergency communication method based on low-Earth orbit satellite networks, characterized in that, The method includes the following steps: The ground station acquires the communication data that needs to be transmitted by the low-orbit satellite and converts the communication data into a binary bit stream, which is then divided into multiple communication bit sequences. All bit values ​​in each communication bit sequence are numbered in position order. All bit values ​​of 1 are combined into a position sequence. By analyzing the extreme value distribution and dispersion of all elements in the first-order difference sequence of the position sequence, the bit spacing difference of the position sequence is determined. Data with a value of 1 in the first-order difference sequence of the position sequence are removed to obtain the interval distribution sequence. Based on the complexity of all elements in the interval distribution sequence, and combined with the number of all elements with a value of 1 in the first-order difference sequence of the position sequence and the bit spacing difference, the irregularity of the information arrangement of the position sequence is determined. By analyzing whether the two consecutive bits following each bit with a value of 1 in each communication bit sequence are 0, each communication bit sequence is divided into multiple subsequences; by analyzing the differences between all subsequences of each communication bit sequence, the difference characteristic value of each communication bit sequence is determined; and by combining the irregularity of the information arrangement of the corresponding position sequence of each communication bit sequence, the information distribution disorder of each communication bit sequence is determined. Based on the aforementioned information distribution disorder, the encoding length of each communication bit sequence is determined; emergency communication of the low-Earth orbit satellite network is then performed based on each communication bit sequence and its encoding length.

2. The emergency communication method based on low-Earth orbit satellite networks as described in claim 1, characterized in that, The bit spacing difference of the position sequence is the result of the positive fusion of the range and standard deviation of all elements in the first-order difference sequence of the position sequence.

3. The emergency communication method based on low-Earth orbit satellite networks as described in claim 1, characterized in that, The expression for the irregularity of the information arrangement of the position sequence is: In the formula, Indicates the irregularity of the arrangement of information in a positional sequence; This represents the complexity of all elements in the interval distribution sequence corresponding to the position sequence; This represents the number of all elements with a value of 1 in the first-order difference sequence of the position sequence; Indicates the bit spacing difference in the position sequence; This indicates a constant that is pre-defined as being greater than 0.

4. The emergency communication method based on low-Earth orbit satellite networks as described in claim 1, characterized in that, The process of dividing each communication bit sequence into multiple sub-sequences includes: In each communication bit sequence, starting from the first bit with a value of 1, if any bit value in the next adjacent bit and the second adjacent bit of the first bit with a value of 1 is not 0, then the next adjacent bit value is added to the current subsequence. The operation of the first bit value of 1 is repeated for the next adjacent bit value. It is determined whether any bit value in the two consecutive bits after the next adjacent bit value is not 0. The above iterative process is repeated until the two consecutive bits after a bit are both 0, thus completing the division of the current subsequence. In the remaining bits of each communication bit sequence, the first bit with a value of 1 is taken as the new starting point, and the process of dividing the current subsequence is repeated to obtain a new subsequence. The above subsequence division process is repeated until the remaining bits of each communication bit sequence no longer contain a bit with a value of 1, thus completing the subsequence division.

5. The emergency communication method based on low-Earth orbit satellite networks as described in claim 1, characterized in that, The difference characteristic value of each communication bit sequence is the mean of the differences between all subsequences of each communication bit sequence.

6. The emergency communication method based on low-Earth orbit satellite networks as described in claim 1, characterized in that, The information distribution disorder of each communication bit sequence is the product of the information arrangement irregularity of the corresponding position sequence of each communication bit sequence and the corresponding difference characteristic value.

7. The emergency communication method based on low-Earth orbit satellite networks as described in claim 1, characterized in that, The expression for the encoded length of each communication bit sequence is: In the formula, Indicates the encoded length of the communication bit sequence i; , These represent 1 / 4 and 1 / 2 of the length of the communication bit sequence i, respectively; , These represent the minimum and maximum values ​​of the disorder in the distribution of all communication bit sequences in the binary bit stream of communication data transmitted by low-Earth orbit satellites, respectively.

8. The emergency communication method based on low-Earth orbit satellite networks as described in claim 1, characterized in that, The emergency communication based on each communication bit sequence and its encoding length for low-Earth orbit satellite networks includes: Each communication bit sequence and its encoding length are used as input to LDPC encoding technology, and the LDPC code of each communication bit sequence is output. The communication bit sequences and their LDPC codes are concatenated and encapsulated into frame data, and all frame data are transmitted to the low-Earth orbit satellite network for emergency communication.

9. An emergency communication system based on a low-Earth orbit satellite network, comprising a memory, a processor, and a computer program stored in the memory and running on the processor, characterized in that, When the processor executes the computer program, it implements the emergency communication method based on a low-Earth orbit satellite network as described in any one of claims 1-8.

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