A Beidou short message encoding method and system for emergency broadcast

Abstract

The invention proposes a Beidou short message encoding method and system for emergency broadcast, comprising the following steps: S1: a command machine generates a short message to be sent to a Beidou terminal; S2: after receiving the sent short message, the Beidou terminal performs decryption and decoding, and if the decoding result meets the requirement, executes step S3; if the decoding result does not meet the requirement, requests retransmission, and re-executes step S1; S3: the Beidou terminal decrypts the message content of the sent short message, generates a terminal response short message and sends it to the command machine, indicating that the sent short message is successfully received; S4: the Beidou terminal encodes the received message content again, generates a communication short message, and sends it to a wireless device end; S5: the wireless device end decodes the communication short message, obtains the message content, and then performs network broadcasting; S6: at regular intervals, the Beidou terminal generates a heartbeat short message and sends it to the command machine, and the heartbeat short message is used to describe the working status of the Beidou terminal.

Description

Technical Field

[0001] The present invention relates to the technical field of emergency short message coding, and in particular to an emergency broadcast Beidou short message coding method and system. Background Art

[0002] The Beidou short message system for emergency broadcasting refers to an important authoritative channel and means for the government to release emergency messages to the public, provide information services, and assist in disaster relief and rescue in the form of Beidou short messages when sudden public events such as natural disasters, accidents, public health and social security occur, when communications with the outside world are interrupted, power is interrupted, and local communication base stations, radio and television transmitters and other communications, transmission lines and other infrastructure are severely damaged. It is an important part of the construction of the national emergency response system and disaster prevention and mitigation system, and an important part of basic urban and rural public services. Among them, the stable and secure transmission of communications between the command aircraft and the Beidou terminal, and between the Beidou terminal and the wireless terminal is crucial.

[0003] The data sent by the emergency Beidou short message may require a multi-level forwarding process, and the communication process needs to ensure the correctness, integrity, confidentiality and security of data transmission. Therefore, it is very necessary to reasonably design and implement the communication mechanism of the emergency Beidou short message to ensure the correctness and integrity of information transmission, for the transmission of multi-level continuous emergency short messages, improve communication quality, and meet the performance index requirements of emergency communications. Summary of the invention

[0004] In view of this, the present invention proposes an emergency broadcast Beidou short message encoding method and system that utilizes the mechanism of emergency broadcast Beidou short message to improve the confidentiality, security and integrity requirements during message transmission in the Beidou system.

[0005] The technical solution of the present invention is achieved in this way:

[0006] On the one hand, the present invention provides a method for encoding an emergency broadcast Beidou short message, comprising the following steps:

[0007] S1: The control machine generates and sends a short message to the Beidou terminal;

[0008] S2: After receiving the short message, the Beidou terminal decrypts and decodes it. If the decoding result meets the requirements, step S3 is executed. If the decoding result does not meet the requirements, the Beidou terminal requests the control machine to resend and re-executes step S1;

[0009] S3: The Beidou terminal decrypts the message content of the sent short message, generates a terminal response short message, and sends the terminal response short message to the control machine, indicating that the sent short message is successfully received;

[0010] S4: The Beidou terminal encodes the received message content again, generates a communication short message, and sends it to the wireless device end;

[0011] S5: After receiving the short communication message, the wireless device decodes the short communication message, obtains the message content, and then broadcasts it to the network;

[0012] S6: At regular intervals, the Beidou terminal generates a short heartbeat message and sends it to the control machine. The short heartbeat message is used to describe the working status of the Beidou terminal.

[0013] On the basis of the above technical scheme, preferably, the command machine in step S1 generates and sends a short message, and constructs and sends the short message in the order of the first frame header, the first session identifier, the first total number of frames, the first frame sequence number, the first data type, the first source level, the first number of terminals, the first terminal sequence number list, UTC time, the number of broadcasts, the content length, the broadcast content and the first verification data; the first frame header is used as the starting identifier of the current frame for sending the short message; the first session identifier is used to determine the connection relationship between the command machine and the Beidou terminal corresponding to the current frame; the first total number of frames is used to indicate that the total number of frames when the short message is sent is greater than a single frame, and the content of the first total number of frames is set when the short message is sent is a single frame; the first frame sequence number is used to indicate that the sequence number of the current frame when the short message is sent is greater than a single frame, and the single frame The content of the first frame number is set; the content of the first data type is uniformly set to the broadcast type; the first source level is used to indicate the regional level of the command machine; the first terminal number indicates the number of Beidou terminals that receive the same content of the sent short message. When it is 0, it means that the short message is sent to the Beidou terminal in broadcast mode; the first terminal number list is used to store the last byte of the resource code of each Beidou terminal; UTC time is used to record the time when the sent short message is sent; the number of broadcasts is used to record the number of executions of the broadcast of the sent short message; the broadcast content is used to record the distribution content corresponding to the current frame when the sent short message is larger than a single frame; the content length is used to limit the number of bytes contained in the broadcast content of the current frame; the first verification data is used to record the verification result of the sent short message at the command machine.

[0014] Preferably, the first verification data is used to record the verification result of the sent short message at the command machine. When encoding, the command machine arranges the first data type, the first source level, the first terminal quantity, the first terminal serial number list and the UTC time in sequence to form the original data, and then encodes the original data using the CRC32 algorithm to obtain the first data string, and verifies the content of the first data string, and saves the verification result as the first verification data at the end of the sent short message; and then uses the DES encryption algorithm to encrypt the encoded first data string.

[0015] Further preferably, the specific content of step S2 is that after the Beidou terminal obtains the sent short message, the DES encryption algorithm is first used to decrypt the content corresponding to the first data type, the first source level, the first terminal number, the first terminal serial number list and the UTC time, and the first data type, the first source level, the first terminal number, the first terminal serial number list, and the UTC time in the decrypted sent short message are extracted. The corresponding first data string encoded, and the CRC32 algorithm is used to decode the first data string. If the decoded verification result corresponds to the first verification data, it indicates that the content of the first data string of the sent short message received by the Beidou terminal is correctly transmitted, indicating that the transmission of the sent short message is successful, and step S3 is continued; if the decoded verification result does not correspond to the first verification data, it indicates that the content of the first data string of the sent short message received by the Beidou terminal is incorrectly transmitted, indicating that the transmission has failed, and step S1 needs to be re-executed to resend the sent short message.

[0016] Further preferably, the specific contents of step S3 include:

[0017] 1) After the Beidou terminal obtains the sent short message and confirms that the sent short message is successfully transmitted, the verification result corresponding to the original data obtained after decoding and the first verification data is stored in the Beidou terminal;

[0018] 2) Beidou terminal builds a terminal reply short message according to the order of the second frame header, the second session identifier, the second data type, the first terminal resource code, the switching identifier, the task type, the second source level, the source identifier, the task time and the second verification data, wherein the second frame header is used as the starting identifier of the terminal reply short message, and the second session identifier is used to identify the current Beidou terminal; the content of the second data type is 0X14, indicating task switching; the first terminal resource code is used to store the resource code of the current Beidou terminal; the switching identifier is used to feedback to the command machine whether the short message transmission is successful; the content of the task type is a short message; the second source level records the regional level of the current Beidou terminal; the content of the source identifier is a short message session identifier; the task time is used to record the reply short message sending time; the second data type, the first terminal resource code, the switching identifier, the task type, the second source level, the source identifier and the task time are sequentially combined to form reply data, and CRC32-MPEG2 is used to obtain a cyclic redundancy check for the reply data to obtain a cyclic redundancy code, and the cyclic redundancy code is written as the content of the second verification data into the terminal reply short message;

[0019] 3) After the command machine receives the terminal response short message sent by the Beidou terminal, it analyzes whether the time of receiving the terminal response short message exceeds the first delay time specified in the task time. If it does not exceed the specified delay time, the second data type, the first terminal resource code, the switching identifier, the task type, the second source level and the source identifier in the terminal response short message are further read, and the response data is reassembled into response data, and the cyclic redundancy check is obtained for the response data again according to CRC32-MPEG2, and the test result is compared with the cyclic redundancy code corresponding to the second verification data. If the comparison result is consistent, it is determined that the corresponding terminal response short message is sent successfully, and the command machine registers the task ready state of the Beidou terminal; if the terminal response short message is not received within the first delay time specified in the task time, the command machine will resend the short message to the Beidou terminal until the terminal response short message is received within the specified delay time or the maximum number of retries is reached; if the Beidou terminal reaches the specified second delay time after sending the terminal response short message, and the short message is not received, the Beidou terminal executes step S4; the second delay time is greater than the first delay time.

[0020] More preferably, the Beidou terminal in step S4 encodes the received message content again, generates a communication short message, and sends it to the wireless device end, specifically including:

[0021] The Beidou terminal constructs a communication short message in the order of the third frame header, the third session identifier, the second total frame number, the second frame sequence number, the third data type, the area code, the second terminal number, the second terminal sequence number list, the instruction length, the instruction content and the third verification data; wherein the third frame header is used as the starting identifier of the communication short message; the third session identifier is used to identify the wireless device end that has a connection relationship with the current Beidou terminal; the second total frame number indicates the total number of frames when the communication short message is greater than a single frame, and the content of the second total frame number is set when the single frame is a single frame; the second frame sequence number indicates the sequence number of the current frame when the communication short message is greater than a single frame, and the content of the second frame sequence number is set when the single frame is a single frame; the third data type is used to set the working status of the wireless device end; the area code indicates the last two digits of the administrative village code; when the second terminal number is not 0, it indicates that a communication short message with the same content is accepted. The wireless device end of the message shall respond after receiving it. When it is 0, it means that the communication short message is sent to the wireless device end in broadcast mode; the second terminal sequence number list is used to store the last byte of the resource code of the wireless device end; the instruction length is used to limit the instruction content length of the communication short message of the current frame; the instruction content is used to record the instruction content sent by the communication short message of the current frame, and the instruction content comes from the broadcast content of at least one frame of the original data decoded by the Beidou terminal; the third data type, the area code, the number of second terminals, the second terminal sequence number list, the instruction length and the instruction content are sequentially combined to form a communication string, and the CRC32 algorithm is used to perform integrity check on the communication string to obtain the checksum as the content of the third verification data; the communication short message is sent by the Beidou terminal to one or more wireless device ends.

[0022] More preferably, the instruction content includes setting the frequency of the wireless device end, querying the information of the wireless device end, and setting the broadcast message sending requirement.

[0023] Further preferably, the specific content of step S6 is that the Beidou terminal constructs a heartbeat short message in the order of the fourth frame header, the fourth session identifier, the fourth data type, the first terminal resource code, the first terminal working status, the first registration identifier, the physical address length, the physical address code, the user identifier, the service frequency, the communication level and the fourth verification data; wherein the fourth frame header is used as the starting identifier of the heartbeat short message; the fourth session identifier is used to determine the connection relationship between the current Beidou terminal and the corresponding command machine; the fourth data type is used to set the heartbeat working status of the Beidou terminal; the first terminal resource code is used to store the resource code of the current Beidou terminal, and its content is the same as the content of the corresponding field of the terminal response short message in step S3; the first terminal working status records the working status of the current Beidou terminal; the first registration identifier records the registration status of the current Beidou terminal ; The physical address length records the number of physical address segments corresponding to the current Beidou terminal, and the default is 6; the user identifier is the user type information provided when the Beidou terminal is first registered; the service frequency records the interval time for sending heartbeat packets; the communication level is the communication priority assigned according to the user type when the Beidou terminal is first registered; the fourth data type, the first terminal resource code, the first terminal working status, the first registration identifier, the physical address length, the physical address code, the user identifier, the service frequency and the communication level are combined into a heartbeat string, and the heartbeat string is subjected to a cyclic redundancy check according to CRC32-MPEG2, and the obtained verification result is saved as the fourth verification data at the end of the heartbeat short message; after each restart or after a third delay time, the Beidou terminal will send a heartbeat short message to the command machine, and the third delay time is greater than the second delay time.

[0024] Preferably, the first source level and the second source level are both one of national, provincial, municipal, county, town or township.

[0025] On the other hand, the present invention also provides an emergency broadcast Beidou short message encoding system, which is used to implement the above-mentioned emergency broadcast Beidou short message encoding method, including:

[0026] The control machine is used to generate and send short messages to several Beidou terminals;

[0027] Several Beidou terminals receive the sent short message, decrypt and decode the sent short message, confirm the integrity of the sent short message according to the decoding result, store the completely received sent short message locally, send a terminal response short message to the control machine, and further generate a communication short message based on the message content of the sent short message;

[0028] Several wireless devices are used to receive short communication messages, decode the short communication messages, obtain the message content and then broadcast it over the network;

[0029] Emergency message receiving terminal, used to receive network broadcasts;

[0030] Among them, several Beidou terminals also regularly send heartbeat short messages to the command machine.

[0031] The present invention provides a Beidou short message encoding method and system for emergency broadcast, which has the following beneficial effects compared with the prior art:

[0032] (1) This application defines the sending-confirmation mechanism between the command machine and the Beidou terminal, and further sets the communication conditions between the Beidou terminal and the wireless device end, so that the wireless device end can actively send short messages to the operator network within a certain range, realize the emergency message release or information service of sudden emergency events, and realize the smooth emergency communication service of multi-level continuous forwarding of emergency short messages;

[0033] (2) The mutual communication between the control machine, Beidou terminal and wireless equipment adopts multiple encoding and encryption processes to ensure the integrity and security of the data. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0035] Figure 1 A communication flow chart of an emergency broadcast Beidou short message encoding method and system of the present invention;

[0036] Figure 2 A schematic diagram of short message communication between a command machine, a Beidou terminal or a wireless device end of an emergency broadcast Beidou short message encoding method and system of the present invention;

[0037] Figure 3 A heartbeat short message communication diagram between a command machine and a Beidou terminal of an emergency broadcast Beidou short message encoding method and system of the present invention;

[0038] Figure 4 A flowchart of a CRC32 generation check code of an emergency broadcast Beidou short message encoding method and system of the present invention;

[0039] Figure 5 The present invention discloses a DES algorithm encryption flow chart of an emergency broadcast Beidou short message encoding method and system. DETAILED DESCRIPTION

[0040] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. 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 creative work are within the scope of protection of the present invention.

[0041] Example: Figure 1-Figure 3 As shown, the present invention provides a method for encoding an emergency broadcast Beidou short message, comprising the following steps:

[0042] S1: The control machine generates a short message and sends it to the Beidou terminal.

[0043] Specifically, the command machine generates and sends a short message by sequentially following the order of a first frame header, a first session identifier, a first total number of frames, a first frame sequence number, a first data type, a first source level, a first number of terminals, a first terminal sequence number list, UTC time, number of broadcasts, content length, broadcast content, and first verification data; wherein, the first frame header is used as a starting identifier of the current frame for sending the short message; the first session identifier is used to determine the connection relationship between the command machine and the Beidou terminal corresponding to the current frame; the first total number of frames is used to indicate that the total number of frames when the short message is sent is greater than a single frame, and in the case of a single frame, the content of the first total number of frames is set; the first frame sequence number is used to indicate that the sequence number of the current frame when the short message is sent is greater than a single frame, and in the case of a single frame, the first frame sequence number is set. Content is set; the content of the first data type is uniformly set to the broadcast type; the first source level is used to indicate the regional level of the command machine; the first terminal number indicates the number of Beidou terminals that receive the same content of the sent short message. When it is 0, it means that the short message is sent to the Beidou terminal in a broadcast mode; the first terminal sequence number list is used to store the last byte of the resource code of each Beidou terminal; UTC time is used to record the time when the sent short message is sent; the number of broadcasts is used to record the number of executions of the broadcast of the sent short message; the broadcast content is used to record the distribution content corresponding to the current frame when the sent short message is larger than a single frame; the content length is used to limit the number of bytes contained in the broadcast content of the current frame; the first verification data is used to record the verification result of the sent short message at the command machine. The first source level is one of the following: country, province, city, county, town or township. The short message sent down records the message type, the designated number of Beidou terminals, the resource code of the Beidou terminal, etc. The content of the last byte of the Beidou terminal resource code within the same geographical level is different, so different Beidou terminals can be distinguished; when the set value of the designated number of Beidou terminals does not match the responded Beidou terminals, the actual number of responded Beidou terminals shall prevail; the level of the source of the sent short message determines the importance, and the content length determines the number of frames and the broadcast content; the first verification data is used to ensure that there is a reliable transmission verification method to ensure that the Beidou terminal accurately receives the broadcast content.

[0044] See Table 1 below, which corresponds to the content and encoding rules of each field of the sent short message.

[0045]

[0046] Table 1: Field contents and coding rules of the short message sent

[0047] The first verification data is used to record the verification result of the sent short message at the command machine. When the command machine encodes, specifically, the first data type, the first source level, the first terminal quantity, the first terminal serial number list and the UTC time are sorted in sequence to form the original data, and then the CRC32 algorithm is used to encode the original data to obtain the first data string, and the content of the first data string is verified, and the verification result is saved as the first verification data at the end of the sent short message; then the DES encryption algorithm is used to encrypt the encoded first data string.

[0048] In order to ensure the integrity of data during transmission, CRC32 cyclic redundancy check is used on the transmitted information. The CRC32 algorithm is used to calculate the original data to obtain a check value. When the receiver receives the data, the same check algorithm is used to calculate the original data. If the calculation result is consistent with the received check value, it means that the data check is correct and this frame of data can be used. If it is inconsistent, it means that an error occurred during the transmission process. This frame of data is discarded and a retransmission request is requested. CRC check is a traditional data error detection function. It performs polynomial calculation on the data and attaches the result to the back of the frame. The receiving device also runs a similar algorithm to ensure the correctness and integrity of data transmission. During the communication process, the duration will change, which can change from 0 to 1 or from 1 to 0. The bit string to be sent is regarded as a polynomial with coefficients of 0 or 1. The sender and receiver agree on a generating polynomial G(x), the highest and lowest order coefficients of which must be 1. The sender uses the bit string and G(x) to perform some operation to obtain the checksum, and adds the checksum at the end of the message so that the polynomial of the frame with the checksum can be divided by G(x). After receiving the message, the receiver divides it by the polynomial G(x). If there is a remainder, the transmission is wrong. Let the expression of the polynomial G(x) be x 32 +x 26 +x 23 +x 22 +x 12 +x 11 +x 10 +x 8 +x 7 +x 5 +x 4 +x 2 +x+1; see attached Figure 4 From the flowchart, we can see that the specific process of the algorithm is:

[0049] First, a generating polynomial G(x) is given, and its order is r. Then, a polynomial with a data string frame number of k bits is given, which is set as M(X). The original frame M(X) is shifted left by r bits, and r zeros are added after M(X). The generated new data string becomes k+r bits, and the polynomial becomes X r M(X).

[0050] Use new data string X r M(X) is divided by the data string corresponding to the generating polynomial G(x), and the remainder R(X) is obtained by applying the modulo-2 operation.

[0051] The remainder R(X) is added to the end of the data string M(X) to generate a new data string T(X). The new data string T(X) is the frame polynomial with checksum to be sent, that is, T(X) = X r M(X)+R(X);

[0052] When the data is received and decoded, T(X) is divided by G(x). If the remainder is 0, the transmission is correct. If the remainder is not 0, the transmission is wrong and needs to be resent.

[0053] Refer to the attached Figure 5 In order to ensure confidentiality and security during data transmission, this application uses DES to encrypt / decrypt information during transmission. DES is a block encryption algorithm that encrypts plaintext in groups, taking a portion of the plaintext in sequence each time. A typical DES uses 64 bits as a group, and the encryption and decryption algorithms are the same. Its key length is 56 bits, because the 8th bit of each group is used for parity check, and the key can be any 56-bit number. Confidentiality depends on the key. The process of its encryption algorithm is as follows:

[0054] The input 64-bit plaintext data block is initially permuted, and the data block is rearranged after permutation, and the output is divided into the first 32 bits and the last 32 bits, which are represented by L0 and R0 respectively;

[0055] Then the 64-bit key is subjected to inherent operations such as XOR, permutation, substitution, and shift operations to obtain 16 sub-keys, which are represented by q1, q2, q3, ..., q 16 express;

[0056] Perform 16 rounds of iterations to obtain the sum L 16 and R 16 ;

[0057] The obtained L 16 and R 16 Perform the inverse operation of the initial permutation to obtain the ciphertext output. The decryption process of the DES algorithm is the inverse process of encryption.

[0058] S2: After receiving the short message, the Beidou terminal decrypts and decodes it. If the decoding result meets the requirements, step S3 is executed. If the decoding result does not meet the requirements, the Beidou terminal requests the control machine to resend and re-executes step S1.

[0059] The specific content of step S2 is that after the Beidou terminal obtains the sent short message, the DES encryption algorithm is first used to decrypt the content corresponding to the first data type, the first source level, the first terminal number, the first terminal sequence number list and the UTC time, and the first data string corresponding to the first data type, the first source level, the first terminal number, the first terminal sequence number list and the UTC time in the decrypted sent short message is extracted, and the CRC32 algorithm is used to decode the first data string. If the verification result after decoding corresponds to the first verification data, it indicates that the content of the first data string of the sent short message received by the Beidou terminal is correctly transmitted, indicating that the transmission of the sent short message is successful, and step S3 is continued; if the verification result after decoding does not correspond to the first verification data, it indicates that the content of the first data string of the sent short message received by the Beidou terminal is incorrectly transmitted, indicating that the transmission fails, and step S1 needs to be re-executed to resend the sent short message. In the content of the resent sent short message, only the UTC time is updated, and the contents of other fields remain unchanged.

[0060] S3: The Beidou terminal decrypts the message content of the sent short message, generates a terminal response short message, and sends the terminal response short message to the control machine, indicating that the sent short message is successfully received.

[0061] The specific contents of step S3 include:

[0062] 1) After the Beidou terminal obtains the sent short message and confirms that the sent short message is successfully transmitted, the verification result corresponding to the original data obtained after decoding and the first verification data is stored in the Beidou terminal;

[0063] 2) Beidou terminal builds a terminal reply short message according to the order of the second frame header, the second session identifier, the second data type, the first terminal resource code, the switching identifier, the task type, the second source level, the source identifier, the task time and the second verification data, wherein the second frame header is used as the starting identifier of the terminal reply short message, and the second session identifier is used to identify the current Beidou terminal; the content of the second data type is 0X14, indicating task switching; the first terminal resource code is used to store the resource code of the current Beidou terminal; the switching identifier is used to feedback to the command machine whether the short message transmission is successful; the content of the task type is a short message; the second source level records the regional level of the current Beidou terminal; the content of the source identifier is a short message session identifier; the task time is used to record the reply short message sending time; the second data type, the first terminal resource code, the switching identifier, the task type, the second source level, the source identifier and the task time are sequentially combined to form reply data, and CRC32-MPEG2 is used to obtain a cyclic redundancy check for the reply data to obtain a cyclic redundancy code, and the cyclic redundancy code is written as the content of the second verification data into the terminal reply short message;

[0064] The second source level is one of the national, provincial, municipal, county, town or township. The short reply message records the information of the Beidou terminal that receives and responds to the short message, including the task type switching, whether the short message is successfully received, whether the short message is received within the specified time, and the time when the short reply message is sent; as well as the verification result of the Beidou terminal on the short reply message.

[0065] As shown in Table 2 below, the content and encoding rules of each field of the response short message correspond.

[0066]

[0067]

[0068] Table 2 Field contents and coding rules of short response message

[0069] 3) After the command machine receives the terminal response short message sent by the Beidou terminal, it analyzes whether the time of receiving the terminal response short message exceeds the first delay time specified in the task time. If it does not exceed the specified delay time, the second data type, the first terminal resource code, the switching identifier, the task type, the second source level and the source identifier in the terminal response short message are further read, and the response data is reassembled into response data, and the cyclic redundancy check is obtained for the response data again according to CRC32-MPEG2, and the test result is compared with the cyclic redundancy code corresponding to the second verification data. If the comparison result is consistent, it is determined that the corresponding terminal response short message is sent successfully, and the command machine registers the task ready state of the Beidou terminal; if the terminal response short message is not received within the first delay time specified in the task time, the command machine will resend the short message to the Beidou terminal until the terminal response short message is received within the specified delay time or the maximum number of retries is reached; if the Beidou terminal reaches the specified second delay time after sending the terminal response short message, and the short message is not received, the Beidou terminal executes step S4; the second delay time is greater than the first delay time. The first delay time determines the delay or reliability of the communication link from the command machine to the Beidou terminal. The first delay time is (necessary transmission time of the content of the short message + necessary first network delay) × M, where M is the maximum number of attempts to send the short message; the second delay time is (necessary transmission time of the content of the reply short message + necessary second network delay) × N, where N is the maximum number of attempts to reply the short message, M and N are integers and N≥M, and the necessary second network delay includes the remaining time of the communication task between the current Beidou terminal and the non-command machine. If the Beidou terminal has not received the resent short message from the command machine after waiting for the second delay time from the moment of sending the reply short message, the Beidou terminal executes step S4.

[0070] S4: The Beidou terminal encodes the received message content again, generates a communication short message, and sends it to the wireless device.

[0071] Specifically including: the Beidou terminal constructs a communication short message in the order of the third frame header, the third session identifier, the second total frame number, the second frame sequence number, the third data type, the area code, the second terminal number, the second terminal sequence number list, the instruction length, the instruction content and the third verification data; wherein the third frame header is used as the starting identifier of the communication short message; the third session identifier is used to identify the wireless device end that has a connection relationship with the current Beidou terminal; the second total frame number indicates that the communication short message is greater than the total number of frames when the single frame is a single frame, and the content of the second total frame number is set; the second frame sequence number indicates the sequence number of the current frame when the communication short message is greater than the single frame, and the content of the second frame sequence number is set when the single frame is a single frame; the third data type is used to set the working status of the wireless device end; the area code indicates the last two digits of the administrative village code; when the second terminal number is not 0, it indicates that the communication with the same content is accepted The wireless device end of the short message shall respond after receiving it. When it is 0, it means that the communication short message is sent to the wireless device end in a broadcast mode; the second terminal sequence number list is used to store the last byte of the resource code of the wireless device end; the instruction length is used to limit the instruction content length of the communication short message of the current frame; the instruction content is used to record the instruction content sent by the communication short message of the current frame, and the instruction content comes from the broadcast content of at least one frame of the original data decoded by the Beidou terminal; the third data type, the area code, the number of second terminals, the second terminal sequence number list, the instruction length and the instruction content are sequentially combined to form a communication string, and the CRC32 algorithm is used to perform integrity check on the communication string to obtain the checksum as the content of the third verification data; the communication short message is sent by the Beidou terminal to one or more wireless device ends. The content of the third verification data can be the communication string CRC32 encoded and then DES encrypted.

[0072] The content of the above instruction content field includes setting the frequency of the wireless device end, querying the information of the wireless device end, and setting the broadcast message sending requirements.

[0073] Table 3 shows the content of each field of the communication short message, i.e. the encoding rules.

[0074]

[0075] Table 3 Communication short message field content and coding rules

[0076] S5: After receiving the short communication message, the wireless device decodes the short communication message, obtains the message content, and then broadcasts it on the network. The wireless device can use the Beidou network or the operator network to broadcast a limited number of short messages, which is particularly suitable for disaster relief broadcasts or emergency broadcasts when local communications are interrupted.

[0077] In order to consider the coverage range of the wireless device end, the coverage range of each wireless device end is set as follows: each wireless device end uses its location as the center of the circle, and wirelessly sends the message content to the terminal of the network operator in the circular range adjacent to the center of the circle. The areas of the circular ranges of different wireless device ends are not exactly the same; after receiving the message content, the terminal of the network operator feeds back a receiving instruction to the wireless device end. The coverage areas of adjacent wireless device ends may overlap, but the overlapping area of ​​the circular range areas shall not exceed 5% of the larger area of ​​the circular ranges, or shall not exceed 10% of the smaller area of ​​the circular ranges; Boolean operations are performed on the areas of the circular ranges of all wireless device ends, which shall cover more than 99% of the area of ​​the corresponding regional level.

[0078] The content of the short message is generated after extracting the message content; after the network operator's terminal receives the message content, it further uses the 2G / 3G / 4G network to transmit the local short message and sends the local short message to unspecified mobile terminals, such as mobile phones, until it receives the received feedback instructions from each unspecified mobile terminal, or the repeated transmission reaches the maximum number of repetitions.

[0079] S6: At regular intervals, the Beidou terminal generates a short heartbeat message and sends it to the control machine. The short heartbeat message is used to describe the working status of the Beidou terminal.

[0080] The specific content is that the Beidou terminal constructs a heartbeat short message in the order of the fourth frame header, the fourth session identifier, the fourth data type, the first terminal resource code, the first terminal working status, the first registration identifier, the physical address length, the physical address code, the user identifier, the service frequency, the communication level and the fourth verification data; wherein the fourth frame header is used as the starting identifier of the heartbeat short message; the fourth session identifier is used to determine the connection relationship between the current Beidou terminal and the corresponding command machine; the fourth data type is used to set the heartbeat working status of the Beidou terminal; the first terminal resource code is used to store the resource code of the current Beidou terminal, and its content is the same as the content of the corresponding field of the terminal response short message in step S3; the first terminal working status records the working status of the current Beidou terminal; the first registration identifier records the registration status of the current Beidou terminal; the physical address length It records the number of physical address segments corresponding to the current Beidou terminal, which defaults to 6; the user identifier is the user type information provided when the Beidou terminal is first registered; the service frequency records the interval time for sending heartbeat packets; the communication level is the communication priority assigned according to the user type when the Beidou terminal is first registered; the fourth data type, the first terminal resource code, the first terminal working status, the first registration identifier, the physical address length, the physical address code, the user identifier, the service frequency and the communication level are combined into a heartbeat string, and a cyclic redundancy check is performed on the heartbeat string according to CRC32-MPEG2, and the obtained verification result is saved as the fourth verification data at the end of the heartbeat short message; after each restart or after a third delay time, the Beidou terminal will send a heartbeat short message to the command machine, and the third delay time is greater than the second delay time.

[0081] The heartbeat short message is used to confirm the online status of the Beidou terminal and ensure that it is in an available state. Therefore, the sending interval is much longer than the message sending verification time.

[0082] In addition, the present invention also provides an emergency broadcast Beidou short message encoding system, which is used to implement the above-mentioned emergency broadcast Beidou short message encoding method, including:

[0083] The control machine is used to generate and send short messages to several Beidou terminals;

[0084] Several Beidou terminals receive the sent short message, decrypt and decode the sent short message, confirm the integrity of the sent short message according to the decoding result, store the completely received sent short message locally, send a terminal response short message to the control machine, and further generate a communication short message based on the message content of the sent short message;

[0085] Several wireless devices are used to receive short communication messages, decode the short communication messages, obtain the message content and then broadcast it over the network;

[0086] Emergency message receiving terminal, used to receive network broadcasts;

[0087] Among them, several Beidou terminals also regularly send heartbeat short messages to the command machine.

[0088] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A Beidou short message encoding method for emergency broadcast, characterized in that: The steps include: S1: The control machine generates and sends a short message to the Beidou terminal; S2: After receiving the short message, the Beidou terminal decrypts and decodes it. If the decoding result meets the requirements, step S3 is executed. If the decoding result does not meet the requirements, the Beidou terminal requests the control machine to resend and re-executes step S1; S3: The Beidou terminal decrypts the message content of the sent short message, generates a terminal response short message, and sends the terminal response short message to the control machine, indicating that the sent short message is successfully received; S4: The Beidou terminal encodes the received message content again, generates a communication short message, and sends it to the wireless device end; S5: After receiving the short communication message, the wireless device decodes the short communication message, obtains the message content, and then broadcasts it to the network; S6: At regular intervals, the Beidou terminal generates a short heartbeat message and sends it to the control machine. The short heartbeat message is used to describe the working status of the Beidou terminal. The command machine in step S1 generates and sends a short message, which is constructed and sent in the order of the first frame header, the first session identifier, the first total number of frames, the first frame sequence number, the first data type, the first source level, the first terminal number, the first terminal sequence number list, the UTC time, the number of broadcasts, the content length, the broadcast content and the first verification data; the first frame header is used as the starting identifier of the current frame of the sent short message; The first session identifier is used to determine the connection relationship between the command machine and the Beidou terminal corresponding to the current frame; the first total frame number is used to indicate the total number of frames when the short message is greater than a single frame, and the content of the first total frame number is set when a single frame is used; the first frame sequence number is used to indicate the sequence number of the current frame when the short message is greater than a single frame, and the content of the first frame sequence number is set when a single frame is used; the content of the first data type is uniformly set to the broadcast type; the first source level is used to indicate the regional level of the command machine; the first terminal quantity indicates the number of Beidou terminals that receive the short messages with the same content, and when it is 0, it indicates that the short message is sent to the Beidou terminal in broadcast mode; the first terminal sequence number list is used to store the last byte of the resource code of each Beidou terminal; UTC time is used to record the time when the short message is sent; The broadcasting times are used to record the execution times of broadcasting and sending short messages; the broadcasting content is used to record the distribution content corresponding to the current frame when the short message sent is larger than a single frame; the content length is used to limit the number of bytes contained in the broadcast content of the current frame; the first verification data is used to record the verification result of the short message sent at the command machine; The first verification data is used to record the verification result of the sent short message at the command machine. When encoding, the command machine sequentially sorts the first data type, the first source level, the first terminal number, the first terminal sequence number list and the UTC time to form the original data, and then uses the CRC32 algorithm to encode the original data to obtain the first data string, and verifies the content of the first data string, and saves the verification result as the first verification data at the end of the sent short message; then uses the DES encryption algorithm to encrypt the encoded first data string; The specific content of step S2 is that after the Beidou terminal obtains the sent short message, the DES encryption algorithm is first used to decrypt the content corresponding to the first data type, the first source level, the first terminal number, the first terminal sequence number list and the UTC time, and the first data type, the first source level, the first terminal number, the first terminal sequence number list, and the UTC time in the decrypted sent short message are extracted. The corresponding first data string after encoding is decoded by the CRC32 algorithm. If the decoded verification result corresponds to the first verification data, it indicates that the content of the first data string of the sent short message received by the Beidou terminal is correctly transmitted, indicating that the transmission of the sent short message is successful, and step S3 is continued; If the decoded verification result does not correspond to the first verification data, it means that the content of the first data string of the sent short message received by the Beidou terminal is incorrectly transmitted, indicating that the transmission has failed, and step S1 needs to be re-executed to resend the sent short message; The specific contents of step S3 include: 1) After the Beidou terminal obtains the sent short message and confirms that the sent short message is successfully transmitted, the verification result corresponding to the original data obtained after decoding and the first verification data is stored in the Beidou terminal; 2) Beidou terminal builds a terminal reply short message according to the order of the second frame header, the second session identifier, the second data type, the first terminal resource code, the switching identifier, the task type, the second source level, the source identifier, the task time and the second verification data, wherein the second frame header is used as the starting identifier of the terminal reply short message, and the second session identifier is used to identify the current Beidou terminal; the content of the second data type is 0X14, indicating task switching; the first terminal resource code is used to store the resource code of the current Beidou terminal; the switching identifier is used to feedback to the command machine whether the short message transmission is successful; the content of the task type is a short message; the second source level records the regional level of the current Beidou terminal; the content of the source identifier is a short message session identifier; the task time is used to record the reply short message sending time; the second data type, the first terminal resource code, the switching identifier, the task type, the second source level, the source identifier and the task time are sequentially combined to form reply data, and CRC32-MPEG2 is used to obtain a cyclic redundancy check for the reply data to obtain a cyclic redundancy code, and the cyclic redundancy code is written as the content of the second verification data into the terminal reply short message; 3) After the command machine receives the terminal response short message sent by the Beidou terminal, it analyzes whether the time of receiving the terminal response short message exceeds the first delay time specified in the task time. If it does not exceed the specified delay time, the second data type, the first terminal resource code, the switching identifier, the task type, the second source level and the source identifier in the terminal response short message are further read, and the response data is reassembled into response data, and the cyclic redundancy check is obtained for the response data according to CRC32-MPEG2 again, and the test result is compared with the cyclic redundancy code corresponding to the second verification data. If the comparison result is consistent, it is determined that the corresponding terminal response short message is sent successfully, and the command machine registers the task ready state of the Beidou terminal; if the terminal response short message is not received within the first delay time specified in the task time, the command machine will resend the short message to the Beidou terminal until the terminal response short message is received within the specified delay time or the maximum number of retries is reached; if the Beidou terminal reaches the specified second delay time after sending the terminal response short message, and does not receive the short message, the Beidou terminal executes step S4; the second delay time is greater than the first delay time; The Beidou terminal described in step S4 encodes the received message content again, generates a communication short message, and sends it to the wireless device end, specifically including: The Beidou terminal constructs a communication short message in the order of the third frame header, the third session identifier, the second total frame number, the second frame sequence number, the third data type, the area code, the second terminal number, the second terminal sequence number list, the instruction length, the instruction content and the third verification data; wherein the third frame header is used as the starting identifier of the communication short message; the third session identifier is used to identify the wireless device end that has a connection relationship with the current Beidou terminal; the second total frame number indicates the total number of frames when the communication short message is greater than a single frame, and the content of the second total frame number is set when the single frame is a single frame; the second frame sequence number indicates the sequence number of the current frame when the communication short message is greater than a single frame, and the content of the second frame sequence number is set when the single frame is a single frame; the third data type is used to set the working status of the wireless device end; the area code indicates the last two digits of the administrative village code; when the second terminal number is not 0, it indicates that a communication short message with the same content is accepted. The wireless device end of the message shall respond after receiving it. When it is 0, it means that the communication short message is sent to the wireless device end in broadcast mode; the second terminal sequence number list is used to store the last byte of the resource code of the wireless device end; the instruction length is used to limit the instruction content length of the communication short message of the current frame; the instruction content is used to record the instruction content sent by the communication short message of the current frame, and the instruction content comes from the broadcast content of at least one frame of the original data decoded by the Beidou terminal; the third data type, the area code, the number of second terminals, the second terminal sequence number list, the instruction length and the instruction content are sequentially combined to form a communication string, and the CRC32 algorithm is used to perform integrity check on the communication string to obtain the checksum as the content of the third verification data; the communication short message is sent by the Beidou terminal to one or more wireless device ends.

2. A Beidou short message encoding method for emergency broadcast according to claim 1, characterized in that: The instruction content includes setting the frequency of the wireless device end, querying the information of the wireless device end, and setting the broadcast message sending requirements.

3. The method for encoding an emergency broadcast Beidou short message according to claim 1, characterized in that: The specific content of step S6 is that the Beidou terminal constructs a heartbeat short message in the order of the fourth frame header, the fourth session identifier, the fourth data type, the first terminal resource code, the first terminal working state, the first registration identifier, the physical address length, the physical address code, the user identifier, the service frequency, the communication level and the fourth verification data; wherein the fourth frame header is used as the starting identifier of the heartbeat short message; The fourth session identifier is used to determine the connection relationship between the current Beidou terminal and the corresponding command machine; the fourth data type is used to set the heartbeat working state of the Beidou terminal; The first terminal resource code is used to store the resource code of the current Beidou terminal, and its content is the same as the content of the corresponding field of the terminal response short message in step S3; the first terminal working state records the working state of the current Beidou terminal; the first registration identifier records the registration state of the current Beidou terminal; the physical address length records the number of physical address segments corresponding to the current Beidou terminal; the user identifier is the user type information provided when the Beidou terminal is first registered; the service frequency records the sending interval of the heartbeat packet; The communication level is the communication priority assigned to the Beidou terminal according to the user type when it is first registered; the fourth data type, the first terminal resource code, the first terminal working status, the first registration identifier, the physical address length, the physical address code, the user identifier, the service frequency and the communication level are combined into a heartbeat string, and the heartbeat string is subjected to a cyclic redundancy check according to CRC32-MPEG2, and the obtained verification result is saved as the fourth verification data at the end of the heartbeat short message; after each restart or after a third delay time, the Beidou terminal will send a heartbeat short message to the command machine, and the third delay time is greater than the second delay time.

4. The method for encoding an emergency broadcast Beidou short message according to claim 1, characterized in that: The first source level and the second source level are both one of country, province, city, county, town or township.

5. An emergency broadcast Beidou short message encoding system, used to implement the emergency broadcast Beidou short message encoding method according to any one of claims 1 to 4, characterized in that: include: The control machine is used to generate and send short messages to several Beidou terminals; Several Beidou terminals receive the sent short message, decrypt and decode the sent short message, confirm the integrity of the sent short message according to the decoding result, store the completely received sent short message locally, send a terminal response short message to the control machine, and further generate a communication short message based on the message content of the sent short message; Several wireless devices are used to receive short communication messages, decode the short communication messages, obtain the message content and then broadcast it over the network; Emergency message receiving terminal, used to receive network broadcasts; Among them, several Beidou terminals also regularly send heartbeat short messages to the command machine.

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