High-availability satellite communication system and method

Abstract

The invention discloses a high-availability satellite communication system and method, the system comprises a central station and a plurality of terminal stations, and the central station is used for network system management and communication process control of the satellite communication system and comprises a network management server and channel control equipment. A network management server configures channel control equipment into a main TDM channel, a standby TDM channel, a control ALOHA channel, a service ALOHA channel and backup equipment according to needs, and if the main TDM channel and the control ALOHA channel equipment of a central station break down, working modes of other channel control equipment are set for replacement; the terminal station is used for network management agent and service communication and comprises channel control equipment, a multi-channel modem, network control agent equipment and service access equipment, and the channel control equipment realizes information interaction with the central station and transmission of burst service information; and the multi-channel modem can realize point-to-point and cluster service communication. The stability and reliability of the satellite communication system and the working efficiency of the central station are improved.

Description

Technical Field

[0001] The present invention relates to the field of satellite communication technology, and in particular to a high-availability satellite communication system and method. Background Art

[0002] Satellite communication is an important means of wireless communication. With its wide application in military, ocean, exploration and other fields, the scale of satellite communication systems is getting larger and larger, which puts higher requirements on its availability and reliability.

[0003] Chinese patent CN 113078936 A discloses a satellite communication system based on FDMA system, which solves the problems of low interaction efficiency, high downtime rate and inability to accurately locate fault areas in traditional satellite communication systems based on FDMA system by improving the architecture of control unit and channel detection method. However, it does not improve the availability and reliability of the system from the root. Summary of the invention

[0004] The object of the present invention is to provide a satellite communication system and method which is stable, reliable and highly available.

[0005] The technical solution to achieve the purpose of the present invention is:

[0006] A high-availability satellite communication system includes a central station and a plurality of terminal stations;

[0007] The central station includes a network management server and a central channel control device, which are used for network management and communication process control of the satellite communication system; the network management server configures the central channel control device into a main TDM channel, a backup TDM channel, a control ALOHA channel, a service ALOHA channel, and a backup device according to needs; the central station requires at least one main TDM channel and a control ALOHA channel; the central channel control device has a channel self-checking function to judge the operating status and whether there is a fault, including two forms of power-on channel self-checking and operating channel self-checking;

[0008] The terminal station includes a terminal channel control device, a multi-channel modem, a network control agent device and a service access device, which are used for network management agent and service communication, including short message service, voice service and data service; the terminal channel control device realizes information interaction with the central station and is also used for the transmission of burst service information; the multi-channel modem realizes point-to-point and cluster service communication; the short message service is provided with a confirmation response mechanism to determine whether the sending and receiving of the short message is successful; the data services of the point-to-point and cluster service communication modes are provided with a conduction test process before the communication link is established, and the formal service communication can be started only after verifying that the satellite channel is unobstructed.

[0009] A high-availability satellite communication method, based on the high-availability satellite communication system, is specifically as follows:

[0010] The central station is used for network management of satellite communication systems and control of communication processes; the network management server configures the central channel control equipment into main TDM channels, backup TDM channels, control ALOHA channels, business ALOHA channels, and backup equipment as needed; the central channel control equipment has a channel self-check function to determine the operating status and whether there is a fault, including two forms: power-on channel self-check and operating channel self-check;

[0011] The terminal station is used for network management agency and business communications, including short message services, voice services and data services; the terminal channel control equipment realizes information interaction with the central station and is also used for the transmission of burst business information; the multi-channel modem realizes point-to-point and cluster business communications; the short message service has a confirmation response mechanism to determine whether the short message is sent and received successfully; the data services of point-to-point and cluster business communication modes have a continuity test process before the communication link is established, and the formal business communication can only start after verifying that the satellite channel is unobstructed.

[0012] Compared with the prior art, the present invention has the following significant advantages:

[0013] (1) It realizes reliable transmission of short messages and data type services between terminal stations, supports point-to-point and cluster communication modes, and realizes network management of satellite communication systems and control of communication processes;

[0014] (2) Setting up a backup central station as a hot backup for the main central station. When the channel control equipment of the main central station is damaged, the backup central station is converted into the main central station, which improves the stability of the satellite communication system.

[0015] (3) The short message service has a confirmation response mechanism to accurately know whether the short message is sent or received successfully;

[0016] (4) Data services in point-to-point and cluster communication modes are equipped with a continuity test process before establishing a communication link. After verifying that the satellite channel is unobstructed, formal business communication can begin, thus improving communication efficiency;

[0017] (5) The central station has a polling mechanism for managing the terminal stations in the network. The channel control device periodically polls the status of the terminal stations. If the terminal station does not respond, the terminal station is forced to leave the network, thereby improving the work efficiency of the central station. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a structural schematic diagram of a high-availability satellite communication system of the present invention.

[0019] Figure 2It is a structural schematic diagram of the central station in the present invention.

[0020] Figure 3 It is a schematic diagram of the priority levels of the central station channel control equipment in the present invention.

[0021] Figure 4 It is a schematic diagram of the switching process of the main central station and the backup central station in the present invention.

[0022] Figure 5 It is a structural schematic diagram of the terminal station in the present invention.

[0023] Figure 6 It is a schematic diagram of the principle of cluster data communication in the present invention.

[0024] Figure 7 It is a schematic diagram of the principle of communication link establishment in the present invention.

[0025] Figure 8 It is a schematic diagram of the principle of the polling mechanism in the present invention. DETAILED DESCRIPTION

[0026] It is easy to understand that according to the technical solution of the present invention, without changing the essential spirit of the present invention, a person skilled in the art can imagine various implementation methods of the present invention. Therefore, the following specific implementation methods and drawings are only exemplary descriptions of the technical solution of the present invention, and should not be regarded as the whole of the present invention or as a limitation or restriction of the technical solution of the present invention.

[0027] Various exemplary embodiments of the present invention will now be described in detail with reference to the accompanying drawings. It should be noted that the relative arrangement of components and steps, numerical expressions and numerical values ​​set forth in these embodiments do not limit the scope of the present invention unless otherwise specifically stated.

[0028] The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the invention, its application, or uses.

[0029] Technologies, methods, and equipment known to ordinary technicians in the relevant art may not be discussed in detail, but where appropriate, the technologies, methods, and equipment should be considered as part of the specification.

[0030] In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not limiting. Therefore, other examples of the exemplary embodiments may have different values.

[0031] Combination Figure 1 , a high-availability satellite communication system of the present invention comprises a central station and a plurality of terminal stations;

[0032] The central station includes a network management server and a central channel control device, which are used for network management and communication process control of the satellite communication system; the network management server configures the central channel control device into a main TDM channel, a backup TDM channel, a control ALOHA channel, a service ALOHA channel, and a backup device according to needs; the central station requires at least one main TDM channel and a control ALOHA channel; the central channel control device has a channel self-checking function to judge the operating status and whether there is a fault, including two forms of power-on channel self-checking and operating channel self-checking;

[0033] The terminal station includes a terminal channel control device, a multi-channel modem, a network control agent device and a service access device, which are used for network management agent and service communication, including short message service, voice service and data service; the terminal channel control device realizes information interaction with the central station and is also used for the transmission of burst service information; the multi-channel modem realizes point-to-point and cluster service communication; the short message service is provided with a confirmation response mechanism to determine whether the sending and receiving of the short message is successful; the data services of the point-to-point and cluster service communication modes are provided with a conduction test process before the communication link is established, and the formal service communication can be started only after verifying that the satellite channel is unobstructed.

[0034] As a specific example, the network management server configures the central channel control device into a main TDM channel, a backup TDM channel, a control ALOHA channel, a service ALOHA channel, and a backup device as needed, such as Figure 2 As shown:

[0035] The main TDM channel device and the backup TDM channel device have the same functions and back up each other. When a fault alarm occurs in the main TDM channel device, the network management server sets the backup channel device to enter the main TDM channel device mode. During this process, the backup TDM channel device remains unchanged to ensure that the TDM channel is online.

[0036] The main TDM channel device and the backup TDM channel device send TDM information to the terminal station at the main TDM or backup TDM frequency point respectively, including channel notification information, parameter setting information, polling information, status control information, channel allocation information and link establishment rejection information;

[0037] The control ALOHA channel device receives control ALOHA information sent by the terminal station at the control ALOHA frequency point, including network access application information, network exit application information, status reporting information and link establishment application information;

[0038] The service ALOHA channel device receives service ALOHA information sent by the terminal station at the service ALOHA frequency point, including short message information;

[0039] The backup device is in a standby state, and realizes the functions of a main TDM channel device, a backup TDM channel device, a control ALOHA channel device or a service ALOHA channel device according to the configuration of the network management server;

[0040] The central station requires at least one main TDM channel and one control ALOHA channel to realize system establishment and management functions. The network management server configures the function according to the self-check status of the central channel control device, firstly protecting the main TDM channel and the control ALOHA channel. If these two central channel control devices fail, the network management server sets the working mode of the remaining central channel control devices for replacement; the priorities of the five central channel control devices are as follows: main TDM channel device, control ALOHA channel device, service ALOHA channel device, standby TDM channel device, backup channel device, such as Figure 3 shown.

[0041] As a specific example, the central station is divided into two forms: a main central station and a backup central station. The backup central station and the main central station have the same configuration. The backup central station serves as a hot backup of the main central station and realizes information synchronization with the main central station through a central channel control device. All central channel control devices of the backup central station are in a receiving mode to receive the status and information of the main central station and the terminal station.

[0042] In the backup central station, one central channel control device receives TDM information sent by the central station at the main TDM frequency, one central channel control device receives TDM information sent by the central station at the backup TDM frequency, one central channel control device receives control ALOHA information sent by the terminal station at the control ALOHA frequency, one central channel control device receives service ALOHA information sent by the terminal station at the service ALOHA frequency, and the remaining backup channel devices are in standby state;

[0043] When the central channel control equipment of the main central station is damaged and only the main TDM channel equipment can be maintained in operation, the ALOHA channel equipment information is controlled to be 0 in the sent TDM information, and this TDM channel equipment is set to the receiving mode after 3 seconds to receive TDM information on the main TDM frequency; if no valid TDM information is received, TDM information is sent again on the main TDM frequency, and this TDM channel equipment is set to the receiving mode after 3 seconds to receive TDM information on the main TDM frequency until valid information is received, and then the main central station is converted to a backup central station and configured as the backup central station function;

[0044] When the backup central station receives TDM information from the main central station and the number of ALOHA channel devices controlled by the main central station is 0, the backup central station is converted to the main central station and configured to function as the main central station. Figure 4 shown.

[0045] As a specific example, the central channel control device of the central station includes one sending channel and one receiving channel, which is used to transmit the information received by the receiving channel to the network management server, and send out the information transmitted by the network management server through the sending channel.

[0046] As a specific example, the channel self-check function of the central channel control device is as follows:

[0047] (1) Power-on channel self-test:

[0048] When the central channel control device is turned on, it is in the backup channel device mode and needs to perform a power-on channel self-test. Only when the receiving and sending status is good can it be set by the network management server as a main TDM channel device, a backup TDM channel device, a control ALOHA channel device or a business ALOHA channel device for use;

[0049] When the central channel control device performs a power-on channel self-test, the network management server transmits monitoring information to the central channel control device. The monitoring information data frame has a format such as:

[0050] {"NUM":64;"TEST":"1234567890123456789012345678901234567890

[0051] 123456789012345678901234";} and sent out through the sending channel at the spare frequency; the receiving channel of the central channel control device receives at the spare frequency, and transmits the received information to the network management server; the network management server compares and analyzes the received information. If the received information has no packet loss for 1500 consecutive packets and is consistent with the sent monitoring information, it is determined that the power-on self-test of this central channel control device is normal;

[0052] The NUM of the monitoring information data frame is the data sequence number, which ranges from 64 to 1518 and is used cyclically; TEST is the data content, and the data length changes with the sequence number and is consistent with the sequence number value; the data of the same sequence number in the monitoring information frame is the same, and is sent cyclically according to the sequence number, once every 20ms, until the power-on self-test is normal; if the correct monitoring information is not received within 3 minutes of the power-on monitoring time, it is determined that the power-on self-test of this central channel control device is faulty and cannot be used;

[0053] (2) Run channel self-test:

[0054] When the central channel control device is set to be the main TDM channel device or the backup TDM channel device, the sending channel always sends information on the TDM frequency and sends out the TDM information transmitted by the network management server. At the same time, the central channel control device performs self-inspection of the running channel. The network management server transmits monitoring information to the central channel control device once every 3 seconds and sends it out through the sending channel on the TDM frequency. The receiving channel of the central channel control device receives at the TDM frequency and transmits the received information to the network management server. The network management server identifies the monitoring information from the information and performs comparative analysis. If the sequence numbers of three consecutive packets of information are incorrect or inconsistent with the sent monitoring information, it is determined that the central channel control device has a self-inspection failure.

[0055] As a specific example, the terminal station includes a terminal channel control device, a multi-channel modem, a network control agent device and a service access device, such as Figure 5 As shown;

[0056] The terminal channel control device is consistent with the central channel control device of the central station and is interoperable with each other. It is used for information exchange between the terminal station and the central station and for transmission of burst service information. The receiving channel of the terminal channel control device receives the short message forwarded by the central station on the main TDM frequency or the backup TDM frequency, and the sending channel sends the short message on the service ALOHA frequency.

[0057] The multi-channel modem includes one service sending channel and multiple service receiving channels, realizing point-to-point communication between two terminal stations and cluster communication between multiple terminal stations. Figure 6 As shown;

[0058] The network management agent device receives TDM information sent by the central station at the main TDM frequency or the backup TDM frequency through the receiving channel of the terminal channel control device, and sends the control ALOHA information at the control ALOHA frequency through the sending channel;

[0059] The terminal station accepts the status control of the central station. If the central station sends a network exit control instruction, the corresponding terminal station ends the ongoing communication, stops sending and receiving information, and enters a standby state.

[0060] As a specific example, the confirmation response mechanism of the short message service in the terminal station is as follows:

[0061] The short message information between the terminal stations needs to be forwarded through the central station. When terminal station 1 sends a short message to terminal station 2, terminal station 1 sends it to the central station on the service ALOHA frequency, and the central station forwards it to terminal station 2 on the TDM frequency.

[0062] The terminal station 1 sends the "short message frame" to the central station on the service ALOHA frequency through the terminal channel control device sending channel. After receiving the "short message frame", the central station replies "sent frame" to the terminal station 1 on the primary / backup TDM frequency. After receiving this reply, the terminal station 1 considers that the short message has been sent; if the "sent frame" replied by the central station is not received after 3 seconds, the sending process is cyclic until the "sent frame" replied by the central station is received; if there is still no reply after sending three times, the terminal station 1 determines that the short message sending has failed;

[0063] The central station receives the "short message frame" sent by terminal station 1, and determines whether terminal station 2 is online. If terminal station 2 is not online, after terminal station 2 successfully accesses the network, the central station sends the "short message frame" to terminal station 2 on the primary / backup TDM frequency point; after terminal station 2 receives the "short message frame", it replies "frame received" to the central station on the service ALOHA frequency point. After receiving this reply, the central station considers that the short message has been sent successfully; if the "frame received" reply from terminal station 2 is not received after 3 seconds, the sending process is cyclic until the "frame received" reply from terminal station 2 is received; if there is still no reply after sending three times, the central station determines that the short message has failed to be sent;

[0064] The central station receives the "received frame" replied by the terminal station 2, and determines whether the terminal station 1 is online. If the terminal station 1 is not online, after the terminal station 1 successfully accesses the network, the central station sends the "successful transmission frame" to the terminal station 1 on the primary / backup TDM frequency point;

[0065] After the central station determines that the short message sending fails, it determines whether the terminal station 1 is online. If the terminal station 1 is not online, the central station sends a "sending failure frame" to the terminal station 1 on the main / backup TDM frequency after the terminal station 1 successfully enters the network.

[0066] As a specific example, the continuity test process in the terminal station, such as Figure 7 As shown, the details are as follows:

[0067] (1) Continuity test process of point-to-point data communication:

[0068] (1.1) Terminal station 1 sends a continuity test frame on service frequency 1, and the frame information is: {"NUM":1; "Ter1Test":0XAA; "Ter2Test":0X55;}, and receives the continuity test frame on service frequency 2; Terminal station 2 sends a continuity test frame on service frequency 2, and the frame information is: {"NUM":1; "Ter1Test":0X55; "Ter2Test":0XAA;}, and receives the continuity test frame on service frequency 1; the continuity test frame is sent every 50ms; "NUM" is the frame number, and the value ranges from 1 to 300; "Ter1Test" is the continuity test result of terminal station 1, 0X55 indicates that the continuity test frame has not been received, 0XAA indicates that the continuity test frame has been sent, and 0XBB indicates that the general test frame has been received;

[0069] (1.2) If terminal station 1 receives a continuity test frame sent by terminal station 2 on service frequency 2, "Ter2Test" in the frame is 0XAA, and the "NUM" values ​​of the three consecutive frames received are continuous, then "Ter2Test" in the continuity test frame sent by terminal station 1 is changed to 0XBB; if terminal station 2 receives a continuity test frame sent by terminal station 1 on service frequency 1, "Ter1Test" in the frame is 0XAA, and the "NUM" values ​​of the three consecutive frames received are continuous, then "Ter1Test" in the continuity test frame sent by terminal station 2 is changed to 0XBB;

[0070] (1.3) If terminal station 1 receives a continuity test frame sent by terminal station 2 on service frequency 2, "Ter1Test" in the frame is 0XBB, and the "NUM" values ​​of the three consecutive frames received are continuous, then the continuity test of terminal station 1 is completed, and no continuity test frames are sent, and the state is changed to data communication; if terminal station 2 receives a continuity test frame sent by terminal station 1 on service frequency 1, "Ter2Test" in the frame is 0XBB, and the "NUM" values ​​of the three consecutive frames received are continuous, then the continuity test of terminal station 2 is completed, and no continuity test frames are sent, and the state is changed to data communication;

[0071] (1.4) If the continuity test frame number "NUM" sent by terminal station 1 or terminal station 2 exceeds 300 and does not switch to data communication state, the continuity test fails and the communication ends;

[0072] (2) The continuity test process of cluster data communication:

[0073] (2.1) Terminal station 1 sends a continuity test frame on service frequency 1, and the frame information is: {"NUM":1; "Ter1Test":0XAA; "Ter2Test":0X55; "Ter3Test":0X55; "Ter4Test":0X55; "Ter5Test":0X55;}, and receives the continuity test frame on service frequency 2, service frequency 3, service frequency 4, and service frequency 5; Terminal station 2 sends a continuity test frame on service frequency 2, and the frame information is: {"NUM":1; "Ter1Test":0X55; "Ter2Test":0XAA; "Ter3Test":0X55; "Ter4Test":0X55; "Ter5Test":0X55;}, and receives the continuity test frame on service frequency 1, service frequency 3, service frequency 4, and service frequency 5; The method for sending the continuity test frame by terminal station 3, terminal station 4, and terminal station 5 is the same as that of terminal station 1;

[0074] (2.2) If terminal station 1 receives a continuity test frame sent by terminal station 2 on service frequency 2, "Ter2Test" in the frame is 0XAA, and the "NUM" values ​​of the three consecutive frames received are continuous, then "Ter2Test" in the continuity test frame sent by terminal station 1 is changed to 0XBB; if terminal station 1 receives a continuity test frame sent by terminal station 3 on service frequency 3, "Ter3Test" in the frame is 0XAA, and the "NUM" values ​​of the three consecutive frames received are continuous, then "Ter3Test" in the continuity test frame sent by terminal station 1 is changed to 0X BB; if terminal station 1 receives a continuity test frame sent by terminal station 4 on service frequency 4, "Ter4Test" in the frame is 0XAA, and the "NUM" values ​​of the three consecutive frames received are continuous, then "Ter4Test" in the continuity test frame sent by terminal station 1 is changed to 0XBB; if terminal station 1 receives a continuity test frame sent by terminal station 5 on service frequency 5, "Ter5Test" in the frame is 0XAA, and the "NUM" values ​​of the three consecutive frames received are continuous, then "Ter5Test" in the continuity test frame sent by terminal station 1 is changed to 0XBB;

[0075] If terminal station 2 receives a continuity test frame sent by terminal station 1 on service frequency 1, and "Ter1Test" in the frame is 0XAA, and the "NUM" values ​​of the three consecutive frames received are continuous, then "Ter1Test" in the continuity test frame sent by terminal station 2 is changed to 0XBB; the continuity test frames sent by terminal station 3, terminal station 4, and terminal station 5 received by terminal station 2 and the processing method are the same as those of terminal station 1, and the continuity test frames received by terminal station 3, terminal station 4, and terminal station 5 and the processing methods are the same as those of terminal station 1;

[0076] (2.3) If terminal station 1 receives the continuity test frame sent by terminal station 2, terminal station 3, terminal station 4, and terminal station 5, if "Ter1Test" in the frame is 0XBB, and the "NUM" value of 3 consecutive frames received from each terminal station is continuous, then the continuity test of terminal station 1 is completed, and no continuity test frame is sent, and the state is changed to data communication; if terminal station 2 receives the continuity test frame sent by terminal station 1, terminal station 3, terminal station 4, and terminal station 5, if "Ter2Test" in the frame is 0XBB, and the "NUM" value of 3 consecutive frames received from each terminal station is continuous, then the continuity test of terminal station 2 is completed, and no continuity test frame is sent, and the state is changed to data communication; the reception and processing methods of the continuity test frame by terminal station 3, terminal station 4, and terminal station 5 are the same as those of terminal station 1;

[0077] (2.4) If the continuity test frame number "NUM" sent by terminal station 1, terminal station 2, terminal station 3, terminal station 4 or terminal station 5 exceeds 300 and does not switch to the data communication state, the continuity test fails and the communication ends.

[0078] As a specific example, the central station has a polling mechanism for the terminal stations in the network, such as Figure 8 As shown, the details are as follows:

[0079] (1) When the terminal station is in the centralized waiting state for access to the network, the central station sends polling signaling to the terminal station on the main TDM frequency and the backup TDM frequency at regular intervals. The format is: {"NUM":1; "CU":0XAA;}, where "CU" is the unique address of the terminal station, and "NUM" is the signaling sequence number, ranging from 1 to 65535. Each CU address is used independently and cyclically; the polling signaling interval of the same terminal station shall not be less than 3s;

[0080] (2) After receiving the polling command sent by the central station, the terminal station sends a polling response signaling on the control ALOHA frequency according to the terminal station status. The format is: {"NUM":1; "CU":0XAA; "STATUS":"Communicating"; "FRQ_SEND":14000000000Hz; "FRQ_RECEIVE":12000000000Hz;}, where "NUM" is consistent with the received polling command "NUM" and "STATUS" is the status of the terminal station at this time, including "centralized waiting status" and "communication status". If "STATUS" is "communication", the signaling should include the transmitting frequency "FRQ_SEND" and the receiving frequency "FRQ_RECEIVE" to report the communication status;

[0081] (3) After receiving the polling response signaling from the terminal station, the central station first confirms whether the polling response is valid based on "NUM" and "CU". If "NUM" and "CU" are the same as the sent polling signaling, the polling response is valid; then it determines whether the status of the terminal station is consistent with the information of the central station. If they are consistent, it continues to perform other operations; if they are inconsistent, it updates the information of the central station; if "NUM" and "CU" are inconsistent with the sent polling signaling, the polling response is invalid;

[0082] (4) If the central station sends three consecutive frames of polling signaling with the value "NUM" and does not receive a related polling response or the response is invalid, it is considered that the terminal is abnormally shut down or faulty, and the status information of the terminal station related to the central station is changed to "exit network". At the same time, a "exit network" status control command is sent to this terminal station.

[0083] The present invention also provides a high-availability satellite communication method, which is based on the high-availability satellite communication system and is specifically as follows:

[0084] The central station is used for network management of satellite communication systems and control of communication processes; the network management server configures the central channel control equipment into main TDM channels, backup TDM channels, control ALOHA channels, business ALOHA channels, and backup equipment as needed; the central channel control equipment has a channel self-check function to determine the operating status and whether there is a fault, including two forms: power-on channel self-check and operating channel self-check;

[0085] The terminal station is used for network management agency and business communications, including short message services, voice services and data services; the terminal channel control equipment realizes information interaction with the central station and is also used for the transmission of burst business information; the multi-channel modem realizes point-to-point and cluster business communications; the short message service has a confirmation response mechanism to determine whether the short message is sent and received successfully; the data services of point-to-point and cluster business communication modes have a continuity test process before the communication link is established, and the formal business communication can only start after verifying that the satellite channel is unobstructed.

[0086] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0087] Example

[0088] like Figure 1 As shown, a highly available satellite communication system provided by this embodiment includes a main central station, a backup central station and multiple terminal stations;

[0089] The main central station and the backup central station back up each other and are used for network management of the satellite communication system and control of the communication process; the central station includes a network management server and a channel control device; the central station includes 1 network management server and 5 channel control devices, and the network management server configures the channel control device into a main TDM channel, a backup TDM channel, a control ALOHA channel, a service ALOHA channel, and a backup device according to needs, such as Figure 2 As shown; the central station requires at least one main TDM channel and a control ALOHA channel. If these two channel control devices fail, the network management server sets the working mode of the remaining channel control devices to replace them; the channel control device has a channel self-check function, which can determine the operating status and whether there is a fault, including two forms of power-on channel self-check and running channel self-check;

[0090] The terminal station includes channel control equipment, multi-channel modem, network control agent equipment and service access equipment, which are used for network management agent and service communication, including short message service, voice service and data service; the channel control equipment realizes information interaction with the central station and can also be used for transmission of burst service information; the multi-channel modem can realize point-to-point and cluster service communication; the short message service is provided with a confirmation response mechanism, which can accurately know whether the short message is sent and received successfully; the data services of the point-to-point and cluster service communication modes are provided with a conduction test process before the communication link is established, and the formal service communication can be started after verifying that the satellite channel is unobstructed.

[0091] As a specific example, the network management server of the central station can configure the channel control device of the central station into a main TDM channel, a backup TDM channel, a control ALOHA channel, a service ALOHA channel, and a backup device as needed, such as Figure 2 As shown;

[0092] The main TDM channel device and the backup TDM channel device have the same functions and back up each other. When a fault alarm occurs in the main TDM channel device, the network management server sets the backup channel device to enter the main TDM channel device mode. During this process, the backup TDM channel device remains unchanged to ensure that the TDM channel is online.

[0093] The main TDM channel device and the backup TDM channel device send TDM information to the terminal station at the main TDM or backup TDM frequency point respectively, including channel notification information, parameter setting information, polling information, status control information, channel allocation information and link establishment rejection information;

[0094] The control ALOHA channel device receives control ALOHA information sent by the terminal station at the control ALOHA frequency point, including network access application information, network exit application information, status reporting information and link establishment application information;

[0095] The service ALOHA channel device receives service ALOHA information sent by the terminal station at the service ALOHA frequency point, including short message information;

[0096] The control ALOHA information and the service ALOHA information are both burst information. Separating the service ALOHA from the control ALOHA can effectively reduce the conflict between the two and improve the success rate of information transmission.

[0097] The backup channel device is in a standby state and can realize the functions of a main TDM channel device, a backup TDM channel device, a control ALOHA channel device or a service ALOHA channel device according to the configuration of the network management server;

[0098] The central station requires at least one main TDM channel and one control ALOHA channel to realize system establishment and management functions. The network management server can configure its functions according to the self-test status of the channel control device, firstly ensuring the main TDM channel and the control ALOHA channel. If these two channel control devices fail, the network management server sets the working mode of the remaining channel control devices for replacement; the priorities of the five channel control devices are as follows: main TDM channel device, control ALOHA channel device, service ALOHA channel device, standby TDM channel device, backup channel device, such as Figure 3 shown.

[0099] In the backup central station, all channel control devices are in receiving mode, receiving the status and information of the main central station and the terminal station, wherein one channel control device receives TDM information sent by the central station at the main TDM frequency, one channel control device receives TDM information sent by the central station at the backup TDM frequency, one channel control device receives control ALOHA information sent by the terminal station at the control ALOHA frequency, one channel control device receives service ALOHA information sent by the terminal station at the service ALOHA frequency, and the remaining backup channel devices are in standby mode;

[0100] When the channel control equipment of the main central station is damaged and only the main TDM channel equipment can be maintained in operation, the ALOHA channel equipment information is controlled to be 0 in the sent TDM information, and this TDM channel equipment is set to the receiving mode after 3 seconds to receive TDM information on the main TDM frequency; if no valid TDM information is received, TDM information is sent again on the main TDM frequency, and this TDM channel equipment is set to the receiving mode after 3 seconds to receive TDM information on the main TDM frequency, and this operation is repeated until valid information is received, and then the main central station is converted to a backup central station and configured as a backup central station;

[0101] When the backup central station receives TDM information from the main central station and the number of ALOHA channel devices controlled by the main central station is 0, the backup central station is converted to the main central station and configured to function as the main central station. Figure 4 shown.

[0102] As a specific example, the channel control device of the central station includes one sending channel and one receiving channel, which is used to transmit the information received by the receiving channel to the network management server, and send out the information transmitted by the network management server through the sending channel.

[0103] As a specific example, the channel self-check function of the channel control device is as follows:

[0104] (1) Power-on channel self-test:

[0105] When the channel control device is turned on, it is in the backup channel device mode and needs to perform a power-on channel self-test. Only when the receiving and sending status is good can it be set by the network management server as a main TDM channel device, a backup TDM channel device, a control ALOHA channel device or a service ALOHA channel device for use;

[0106] When the channel control device performs a power-on channel self-test, the network management server transmits monitoring information to the channel control device. The monitoring information data frame has a format such as:

[0107] {"NUM":64;"TEST":"1234567890123456789012345678901234567890

[0108] 123456789012345678901234";} and sent out through the sending channel at the spare frequency; the receiving channel of the channel control device receives at the spare frequency, and transmits the received information to the network management server; the network management server compares and analyzes the received information. If the received information has no packet loss for 1500 consecutive packets and is consistent with the sent monitoring information, it is determined that the power-on self-test of this channel control device is normal;

[0109] "NUM" of the monitoring information data frame is the data sequence number, which ranges from 64 to 1518 and is used cyclically; "TEST" is the data content, and the data length changes with the sequence number and is consistent with the sequence number value; the data of the same sequence number in the monitoring information frame is the same, and is sent cyclically according to the sequence number, once every 20ms, until the power-on self-test is normal; if the power-on monitoring time exceeds 3 minutes and the correct monitoring information is still not received, it is determined that the power-on self-test of this channel control device is faulty and cannot be used;

[0110] (2) Run channel self-test:

[0111] When the channel control device is set to be the main TDM channel device or the backup TDM channel device, the sending channel always sends information on the TDM frequency and sends out the TDM information transmitted by the network management server. At the same time, the channel control device performs channel self-inspection. The network management server transmits monitoring information to the channel control device once every 3 seconds and sends it out through the sending channel on the TDM frequency. The receiving channel of the channel control device receives the information at the TDM frequency and transmits the received information to the network management server. The network management server identifies the monitoring information from the information and performs comparative analysis. If the sequence numbers of three consecutive packets of information are incorrect or inconsistent with the sent monitoring information, it is determined that the channel control device has a self-inspection failure.

[0112] As a specific example, the terminal station includes a channel control device, a multi-channel modem, a network control agent device and a service access device, such as Figure 5 As shown;

[0113] The channel control device is consistent with the channel control device of the central station and can be used universally, and is used for information exchange between the terminal station and the central station, and is also used for transmission of burst service information; the receiving channel of the channel control device receives the short message forwarded by the central station on the main TDM frequency or the backup TDM frequency, and the sending channel sends the short message on the service ALOHA frequency;

[0114] The multi-channel modem 1 includes one service sending channel and four service receiving channels, and can realize cluster communication between five terminal stations. Figure 6 As shown, the service sending channel of the multi-channel modem 1 of the terminal station 1 sends service information on the service frequency 1, the service receiving channel 1 receives service information on the service frequency 2, the service receiving channel 2 receives service information on the service frequency 3, the service receiving channel 3 receives service information on the service frequency 4, and the service receiving channel 4 receives service information on the service frequency 5; the terminal station 2, the terminal station 3, and the terminal station 4 are similar to the terminal station 1;

[0115] The channel control device comprises a sending channel and a receiving channel. The network management agent receives TDM information sent by the central station at the main TDM frequency or the backup TDM frequency through the receiving channel of the channel control device, and sends control ALOHA information, such as network access application, at the control ALOHA frequency through the sending channel;

[0116] The terminal station accepts the status control of the central station. For example, if the central station sends a "network exit" control instruction, the corresponding terminal station ends the ongoing communication, stops sending and receiving information, and enters a standby state.

[0117] As a specific example, the short message service confirmation response mechanism is as follows:

[0118] The short message information between the terminal stations needs to be forwarded through the central station. When terminal station 1 sends a short message to terminal station 2, terminal station 1 sends it to the central station on the service ALOHA frequency, and the central station forwards it to terminal station 2 on the TDM frequency.

[0119] The terminal station 1 sends the "short message frame" to the central station on the service ALOHA frequency through the channel control device. After receiving the "short message frame", the central station replies "sent frame" to the terminal station 1 on the primary / backup TDM frequency. After receiving this reply, the terminal station 1 considers that the short message has been sent; if the "sent frame" replied by the central station is not received after 3 seconds, the above process is repeated until the "sent frame" replied by the central station is received; if there is still no reply after sending three times, the terminal station 1 determines that the short message has failed to be sent;

[0120] The central station receives the "short message frame" sent by terminal station 1, and determines whether terminal station 2 is online. If terminal station 2 is not online, after terminal station 2 successfully accesses the network, the central station sends the "short message frame" to terminal station 2 on the primary / backup TDM frequency point; after terminal station 2 receives the "short message frame", it replies "frame received" to the central station on the service ALOHA frequency point. After receiving this reply, the central station considers that the short message has been sent successfully; if the "frame received" reply from terminal station 2 is not received after 3 seconds, the aforementioned process is repeated until the "frame received" reply from terminal station 2 is received; if there is still no reply after sending three times, the central station determines that the short message has failed to be sent;

[0121] The central station receives the "received frame" replied by the terminal station 2, and determines whether the terminal station 1 is online. If the terminal station 1 is not online, after the terminal station 1 successfully accesses the network, the central station sends the "successful transmission frame" to the terminal station 1 on the primary / backup TDM frequency point;

[0122] After the central station determines that the short message sending fails, it determines whether the terminal station 1 is online. If the terminal station 1 is not online, the central station sends a "sending failure frame" to the terminal station 1 on the main / backup TDM frequency after the terminal station 1 successfully enters the network.

[0123] As a specific example, the conduction test process, such as Figure 7 As shown, the details are as follows:

[0124] (1) Continuity test process of point-to-point data communication:

[0125] (1.1) Terminal station 1 sends a continuity test frame on service frequency 1, and the frame information is: {"NUM":1; "Ter1Test":0XAA; "Ter2Test":0X55;}, and receives the continuity test frame on service frequency 2; Terminal station 2 sends a continuity test frame on service frequency 2, and the frame information is: {"NUM":1; "Ter1Test":0X55; "Ter2Test":0XAA;}, and receives the continuity test frame on service frequency 1; the continuity test frame is sent every 50ms; "NUM" is the frame number, and the value ranges from 1 to 300; "Ter1Test" is the continuity test result of terminal station 1, 0X55 indicates that the continuity test frame has not been received, 0XAA indicates that the continuity test frame has been sent, and 0XBB indicates that the general test frame has been received;

[0126] (1.2) If terminal station 1 receives a continuity test frame sent by terminal station 2 on service frequency 2, "Ter2Test" in the frame is 0XAA, and the "NUM" values ​​of the three consecutive frames received are continuous, then "Ter2Test" in the continuity test frame sent by terminal station 1 is changed to 0XBB; if terminal station 2 receives a continuity test frame sent by terminal station 1 on service frequency 1, "Ter1Test" in the frame is 0XAA, and the "NUM" values ​​of the three consecutive frames received are continuous, then "Ter1Test" in the continuity test frame sent by terminal station 2 is changed to 0XBB;

[0127] (1.3) If terminal station 1 receives a continuity test frame sent by terminal station 2 on service frequency 2, "Ter1Test" in the frame is 0XBB, and the "NUM" values ​​of the three consecutive frames received are continuous, then the continuity test of terminal station 1 is completed, and no continuity test frames are sent, and the state is changed to data communication; if terminal station 2 receives a continuity test frame sent by terminal station 1 on service frequency 1, "Ter2Test" in the frame is 0XBB, and the "NUM" values ​​of the three consecutive frames received are continuous, then the continuity test of terminal station 2 is completed, and no continuity test frames are sent, and the state is changed to data communication;

[0128] (1.4) If the continuity test frame number "NUM" sent by terminal station 1 or terminal station 2 exceeds 300 and does not switch to data communication state, the continuity test fails and the communication ends;

[0129] (2) The continuity test process of cluster data communication:

[0130] (2.1) Terminal station 1 sends a continuity test frame on service frequency 1, and the frame information is: {"NUM":1; "Ter1Test":0XAA; "Ter2Test":0X55; "Ter3Test":0X55; "Ter4Test":0X55; "Ter5Test":0X55;}, and receives the continuity test frame on service frequency 2, service frequency 3, service frequency 4, and service frequency 5; Terminal station 2 sends a continuity test frame on service frequency 2, and the frame information is: {"NUM":1; "Ter1Test":0X55; "Ter2Test":0XAA; "Ter3Test":0X55; "Ter4Test":0X55; "Ter5Test":0X55;}, and receives the continuity test frame on service frequency 1, service frequency 3, service frequency 4, and service frequency 5; The method for sending the continuity test frame by terminal station 3, terminal station 4, and terminal station 5 is the same as that of terminal station 1;

[0131] (2.2) If terminal station 1 receives a continuity test frame sent by terminal station 2 on service frequency 2, "Ter2Test" in the frame is 0XAA, and the "NUM" values ​​of the three consecutive frames received are continuous, then "Ter2Test" in the continuity test frame sent by terminal station 1 is changed to 0XBB; if terminal station 1 receives a continuity test frame sent by terminal station 3 on service frequency 3, "Ter3Test" in the frame is 0XAA, and the "NUM" values ​​of the three consecutive frames received are continuous, then "Ter3Test" in the continuity test frame sent by terminal station 1 is changed to 0X BB; if terminal station 1 receives a continuity test frame sent by terminal station 4 on service frequency 4, "Ter4Test" in the frame is 0XAA, and the "NUM" values ​​of the three consecutive frames received are continuous, then "Ter4Test" in the continuity test frame sent by terminal station 1 is changed to 0XBB; if terminal station 1 receives a continuity test frame sent by terminal station 5 on service frequency 5, "Ter5Test" in the frame is 0XAA, and the "NUM" values ​​of the three consecutive frames received are continuous, then "Ter5Test" in the continuity test frame sent by terminal station 1 is changed to 0XBB;

[0132] If terminal station 2 receives a continuity test frame sent by terminal station 1 on service frequency 1, and "Ter1Test" in the frame is 0XAA, and the "NUM" values ​​of the three consecutive frames received are continuous, then "Ter1Test" in the continuity test frame sent by terminal station 2 is changed to 0XBB; the continuity test frames sent by terminal station 3, terminal station 4, and terminal station 5 received by terminal station 2 and the processing method are the same as those of terminal station 1, and the continuity test frames received by terminal station 3, terminal station 4, and terminal station 5 and the processing methods are the same as those of terminal station 1;

[0133] (2.3) If terminal station 1 receives the continuity test frame sent by terminal station 2, terminal station 3, terminal station 4, and terminal station 5, if "Ter1Test" in the frame is 0XBB, and the "NUM" value of 3 consecutive frames received from each terminal station is continuous, then the continuity test of terminal station 1 is completed, and no continuity test frame is sent, and the state is changed to data communication; if terminal station 2 receives the continuity test frame sent by terminal station 1, terminal station 3, terminal station 4, and terminal station 5, if "Ter2Test" in the frame is 0XBB, and the "NUM" value of 3 consecutive frames received from each terminal station is continuous, then the continuity test of terminal station 2 is completed, and no continuity test frame is sent, and the state is changed to data communication; the reception and processing methods of the continuity test frame by terminal station 3, terminal station 4, and terminal station 5 are the same as those of terminal station 1;

[0134] (2.4) If the continuity test frame number "NUM" sent by terminal station 1, terminal station 2, terminal station 3, terminal station 4 or terminal station 5 exceeds 300 and does not switch to the data communication state, the continuity test fails and the communication ends.

[0135] As a specific example, the central station has a polling mechanism for the terminal stations in the network, such as Figure 8 As shown, specifically:

[0136] (1) When the terminal station is in the centralized waiting state for access to the network, the central station periodically sends polling signaling to the terminal station on the main TDM frequency and the backup TDM frequency, the format of which is: {"NUM":1; "CU":0XAA;}, where "CU" is the unique address of the terminal station, and "NUM" is the signaling sequence number, ranging from 1 to 65535, and each CU address is used independently and cyclically; the polling signaling interval of the same terminal station is not less than 3s;

[0137] (2) After receiving the polling command sent by the central station, the terminal station sends a polling response signaling on the control ALOHA frequency according to the terminal station status. The format is: {"NUM":1; "CU":0XAA; "STATUS":"Communicating"; "FRQ_SEND":14000000000Hz; "FRQ_RECEIVE":12000000000Hz;}, where "NUM" is consistent with the received polling command "NUM" and "STATUS" is the status of the terminal station at this time, including "centralized waiting status" and "communication status". If "STATUS" is "communication", the signaling should include the transmitting frequency "FRQ_SEND" and the receiving frequency "FRQ_RECEIVE" to report the communication status;

[0138] (3) After receiving the polling response signaling from the terminal station, the central station first confirms whether the polling response is valid based on "NUM" and "CU". If "NUM" and "CU" are the same as the sent polling signaling, the polling response is valid; then it determines whether the status of the terminal station is consistent with the information of the central station. If they are consistent, it continues to perform other operations; if they are inconsistent, it updates the information of the central station; if "NUM" and "CU" are inconsistent with the sent polling signaling, the polling response is invalid;

[0139] (4) If the central station sends three consecutive frames of polling signaling with the value "NUM" and does not receive a related polling response or the response is invalid, it is considered that the terminal is abnormally shut down or faulty, and the status information of the terminal station related to the central station is changed to "exit network". At the same time, a "exit network" status control command is sent to this terminal station.

[0140] The above are only preferred embodiments of the present invention. It should be pointed out that, for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A high-availability satellite communication system, characterized in that: It includes a central station and multiple terminal stations; The central station includes a network management server and a central channel control device, which are used for network management and communication process control of the satellite communication system; the network management server configures the central channel control device into a main TDM channel, a backup TDM channel, a control ALOHA channel, a service ALOHA channel, and a backup device according to needs; the central station requires at least one main TDM channel and a control ALOHA channel; the central channel control device has a channel self-checking function to judge the operating status and whether there is a fault, including two forms of power-on channel self-checking and operating channel self-checking; The terminal station includes a terminal channel control device, a multi-channel modem, a network control agent device and a service access device, which are used for network management agent and service communication, including short message service, voice service and data service; the terminal channel control device realizes information interaction with the central station and is also used for the transmission of burst service information; the multi-channel modem realizes point-to-point and cluster service communication; the short message service is provided with a confirmation response mechanism to determine whether the sending and receiving of the short message is successful; the data services of the point-to-point and cluster service communication modes are provided with a conduction test process before the communication link is established, and the formal service communication can be started only after verifying that the satellite channel is unobstructed.

2. The high-availability satellite communication system according to claim 1, characterized in that: The network management server configures the central channel control device into a main TDM channel, a backup TDM channel, a control ALOHA channel, a service ALOHA channel, and a backup device as required, wherein: The main TDM channel device and the backup TDM channel device have the same functions and back up each other. When a fault alarm occurs in the main TDM channel device, the network management server sets the backup channel device to enter the main TDM channel device mode. During this process, the backup TDM channel device remains unchanged to ensure that the TDM channel is online. The main TDM channel device and the backup TDM channel device send TDM information to the terminal station at the main TDM or backup TDM frequency point respectively, including channel notification information, parameter setting information, polling information, status control information, channel allocation information and link establishment rejection information; The control ALOHA channel device receives control ALOHA information sent by the terminal station at the control ALOHA frequency point, including network access application information, network exit application information, status reporting information and link establishment application information; The service ALOHA channel device receives service ALOHA information sent by the terminal station at the service ALOHA frequency point, including short message information; The backup device is in a standby state, and realizes the functions of a main TDM channel device, a backup TDM channel device, a control ALOHA channel device or a service ALOHA channel device according to the configuration of the network management server; The central station requires at least one main TDM channel and one control ALOHA channel to realize system establishment and management functions. The network management server configures the function according to the self-test status of the central channel control device, firstly protecting the main TDM channel and the control ALOHA channel. If these two central channel control devices fail, the network management server sets the working mode of the remaining central channel control devices for replacement; the priorities of the five central channel control devices are in the following order: main TDM channel device, control ALOHA channel device, service ALOHA channel device, spare TDM channel device, and backup channel device.

3. The high-availability satellite communication system according to claim 1, characterized in that: The central station is divided into two forms: a main central station and a backup central station. The backup central station has the same configuration as the main central station. The backup central station serves as a hot backup for the main central station and realizes information synchronization with the main central station through the central channel control device. All central channel control equipment of the backup central station is in receiving mode, receiving the status and information of the main central station and terminal stations; In the backup central station, one central channel control device receives TDM information sent by the central station at the main TDM frequency, one central channel control device receives TDM information sent by the central station at the backup TDM frequency, one central channel control device receives control ALOHA information sent by the terminal station at the control ALOHA frequency, one central channel control device receives service ALOHA information sent by the terminal station at the service ALOHA frequency, and the remaining backup channel devices are in standby state; When the central channel control equipment of the main central station is damaged and only the main TDM channel equipment can be maintained in operation, the ALOHA channel equipment information is controlled to be 0 in the sent TDM information, and this TDM channel equipment is set to the receiving mode after 3 seconds to receive TDM information on the main TDM frequency; if no valid TDM information is received, TDM information is sent again on the main TDM frequency, and this TDM channel equipment is set to the receiving mode after 3 seconds to receive TDM information on the main TDM frequency until valid information is received, and then the main central station is converted to a backup central station and configured as the backup central station function; When the backup central station receives TDM information sent by the main central station and the number of controlled ALOHA channel devices of the main central station is 0, the backup central station is converted into the main central station and configured with the function of the main central station.

4. The high-availability satellite communication system according to claim 1, characterized in that: The central channel control device of the central station comprises a sending channel and a receiving channel, which is used to transmit the information received by the receiving channel to the network management server, and at the same time send out the information transmitted by the network management server through the sending channel.

5. The high-availability satellite communication system according to claim 1, characterized in that: The channel self-checking function of the central channel control device is as follows: (1) Power-on channel self-test: When the central channel control device is turned on, it is in the backup channel device mode and needs to perform a power-on channel self-test. Only when the receiving and sending status is good can it be set by the network management server as a main TDM channel device, a backup TDM channel device, a control ALOHA channel device or a business ALOHA channel device for use; When the central channel control device performs a power-on channel self-test, the network management server transmits monitoring information to the central channel control device, monitoring information data frames, and sends them out through the sending channel at the standby frequency point; the receiving channel of the central channel control device receives at the standby frequency point and transmits the received information to the network management server; The network management server compares and analyzes the received information. If the received information has no packet loss for 1500 consecutive packets and is consistent with the sent monitoring information, it is determined that the power-on self-test of this central channel control device is normal; The NUM of the monitoring information data frame is the data sequence number, which ranges from 64 to 1518 and is used cyclically; TEST is the data content, and the data length changes with the sequence number and is consistent with the sequence number value; the data of the same sequence number in the monitoring information frame is the same, and is sent cyclically according to the sequence number, once every 20ms, until the power-on self-test is normal; If the correct monitoring information is not received within 3 minutes of the power-on monitoring time, the central channel control device is judged to have a power-on self-test failure and cannot be used; (2) Run channel self-test: When the central channel control device is set to be the main TDM channel device or the standby TDM channel device, the sending channel always sends information on the TDM frequency point, and sends out the TDM information transmitted by the network management server. At the same time, the central channel control device performs a self-check of the running channel. The network management server transmits monitoring information to the central channel control device once every 3 seconds, and sends it out through the sending channel on the TDM frequency point; the receiving channel of the central channel control device receives at the TDM frequency point, and transmits the received information to the network management server; The network management server identifies the monitoring information from the information and performs comparative analysis. If the sequence numbers of three consecutive packets of information are incorrect or inconsistent with the sent monitoring information, it is determined that the central channel control device has a self-test failure.

6. The high-availability satellite communication system according to claim 1, characterized in that: The terminal station includes a terminal channel control device, a multi-channel modem, a network control agent device and a service access device; The terminal channel control device is consistent with the central channel control device of the central station and is interoperable with each other. It is used for information exchange between the terminal station and the central station and for transmission of burst service information. The receiving channel of the terminal channel control device receives the short message forwarded by the central station on the main TDM frequency or the backup TDM frequency, and the sending channel sends the short message on the service ALOHA frequency. The multi-channel modem includes one service transmission channel and multiple service reception channels, realizing point-to-point communication between two terminal stations and cluster communication between multiple terminal stations; The network management agent device receives TDM information sent by the central station at the main TDM frequency or the backup TDM frequency through the receiving channel of the terminal channel control device, and sends the control ALOHA information at the control ALOHA frequency through the sending channel; The terminal station accepts the status control of the central station. If the central station sends a network exit control instruction, the corresponding terminal station ends the ongoing communication, stops sending and receiving information, and enters a standby state.

7. The high-availability satellite communication system according to claim 1, characterized in that: The confirmation response mechanism of the short message service in the terminal station is as follows: The short message information between the terminal stations needs to be forwarded through the central station. When terminal station 1 sends a short message to terminal station 2, terminal station 1 sends it to the central station on the service ALOHA frequency, and the central station forwards it to terminal station 2 on the TDM frequency. The terminal station 1 sends the "short message frame" to the central station on the service ALOHA frequency through the terminal channel control device sending channel. After receiving the "short message frame", the central station replies "sent frame" to the terminal station 1 on the primary / backup TDM frequency. After receiving this reply, the terminal station 1 considers that the short message has been sent; if the "sent frame" replied by the central station is not received after 3 seconds, the sending process is cyclic until the "sent frame" replied by the central station is received; After sending the message three times and still receiving no reply, the terminal station 1 determines that the short message sending has failed; The central station receives the "short message frame" sent by the terminal station 1, and determines whether the terminal station 2 is online. If the terminal station 2 is not online, the central station sends the "short message frame" to the terminal station 2 on the primary / backup TDM frequency after the terminal station 2 successfully accesses the network; after the terminal station 2 receives the "short message frame", it replies "the frame has been received" to the central station on the service ALOHA frequency. After receiving this reply, the central station considers that the short message has been sent successfully; if the "frame has been received" reply from the terminal station 2 is not received after 3 seconds, the sending process is cyclic until the "frame has been received" reply from the terminal station 2 is received; After sending three times without any reply, the central station determines that the short message has failed to be sent; The central station receives the "received frame" replied by the terminal station 2, and determines whether the terminal station 1 is online. If the terminal station 1 is not online, the central station sends the "successful transmission frame" to the terminal station 1 on the primary / backup TDM frequency after the terminal station 1 successfully accesses the network. After the central station determines that the short message fails to be sent, it determines whether the terminal station 1 is online. If the terminal station 1 is not online, the central station sends a "sending failure frame" to the terminal station 1 on the primary / backup TDM frequency after the terminal station 1 successfully accesses the network.

8. The high-availability satellite communication system according to claim 1, characterized in that: The continuity test process in the terminal station is as follows: (1) Continuity test process of point-to-point data communication: (1.1) Terminal station 1 sends a continuity test frame on service frequency 1, and the frame information is: {"NUM":1; "Ter1Test":0XAA; "Ter2Test":0X55;}, and receives the continuity test frame on service frequency 2; Terminal station 2 sends a continuity test frame on service frequency 2, and the frame information is: {"NUM":1; "Ter1Test":0X55; "Ter2Test":0XAA;}, and receives the continuity test frame on service frequency 1; the continuity test frame is sent every 50ms; "NUM" is the frame number, and the value ranges from 1 to 300; "Ter1Test" is the continuity test result of terminal station 1, 0X55 indicates that the continuity test frame has not been received, 0XAA indicates that the continuity test frame has been sent, and 0XBB indicates that the general test frame has been received; (1.2) If terminal station 1 receives a continuity test frame sent by terminal station 2 on service frequency 2, "Ter2Test" in the frame is 0XAA, and the "NUM" values ​​of the three consecutive frames received are continuous, then "Ter2Test" in the continuity test frame sent by terminal station 1 is changed to 0XBB; if terminal station 2 receives a continuity test frame sent by terminal station 1 on service frequency 1, "Ter1Test" in the frame is 0XAA, and the "NUM" values ​​of the three consecutive frames received are continuous, then "Ter1Test" in the continuity test frame sent by terminal station 2 is changed to 0XBB; (1.3) If terminal station 1 receives a continuity test frame sent by terminal station 2 on service frequency 2, "Ter1Test" in the frame is 0XBB, and the "NUM" values ​​of the three consecutive frames received are continuous, then the continuity test of terminal station 1 is completed, and no continuity test frames are sent, and the state is changed to data communication; if terminal station 2 receives a continuity test frame sent by terminal station 1 on service frequency 1, "Ter2Test" in the frame is 0XBB, and the "NUM" values ​​of the three consecutive frames received are continuous, then the continuity test of terminal station 2 is completed, and no continuity test frames are sent, and the state is changed to data communication; (1.4) If the continuity test frame number "NUM" sent by terminal station 1 or terminal station 2 exceeds 300 and does not switch to data communication state, the continuity test fails and the communication ends; (2) The continuity test process of cluster data communication: (2.1) Terminal station 1 sends a continuity test frame on service frequency 1, and the frame information is: {"NUM":1; "Ter1Test":0XAA; "Ter2Test":0X55; "Ter3Test":0X55; "Ter4Test":0X55; "Ter5Test":0X55;}, and receives the continuity test frames on service frequency 2, service frequency 3, service frequency 4, and service frequency 5; Terminal station 2 sends a continuity test frame on service frequency 2, and the frame information is: {"NUM":1; "Ter1Test":0X55; "Ter2Test":0XAA; "Ter3Test":0X55; "Ter4Test":0X55; "Ter5Test":0X55;}, and receives the continuity test frames on service frequency 1, service frequency 3, service frequency 4, and service frequency 5; The method for sending the continuity test frame by terminal station 3, terminal station 4, and terminal station 5 is the same as that of terminal station 1; (2.2) If terminal station 1 receives a continuity test frame sent by terminal station 2 on service frequency 2, "Ter2Test" in the frame is 0XAA, and the "NUM" values ​​of the three consecutive frames received are continuous, then "Ter2Test" in the continuity test frame sent by terminal station 1 is changed to 0XBB; If terminal station 1 receives a continuity test frame sent by terminal station 3 on service frequency 3, "Ter3Test" in the frame is 0XAA, and the "NUM" values ​​of the three consecutive frames received are continuous, then "Ter3Test" in the continuity test frame sent by terminal station 1 is changed to 0XBB; If terminal station 1 receives a continuity test frame sent by terminal station 4 on service frequency 4, "Ter4Test" in the frame is 0XAA, and the "NUM" values ​​of the three consecutive frames received are continuous, then "Ter4Test" in the continuity test frame sent by terminal station 1 is changed to 0XBB; If terminal station 1 receives a continuity test frame sent by terminal station 5 on service frequency 5, "Ter5Test" in the frame is 0XAA, and the "NUM" values ​​of the three consecutive frames received are continuous, then "Ter5Test" in the continuity test frame sent by terminal station 1 is changed to 0XBB; If terminal station 2 receives a continuity test frame sent by terminal station 1 on service frequency 1, and "Ter1Test" in the frame is 0XAA, and the "NUM" values ​​of the three consecutive frames received are continuous, then "Ter1Test" in the continuity test frame sent by terminal station 2 is changed to 0XBB; the continuity test frames sent by terminal station 3, terminal station 4, and terminal station 5 received by terminal station 2 and the processing method are the same as those of terminal station 1, and the continuity test frames received by terminal station 3, terminal station 4, and terminal station 5 and the processing methods are the same as those of terminal station 1; (2.3) If terminal station 1 receives the continuity test frames sent by terminal station 2, terminal station 3, terminal station 4, and terminal station 5, if "Ter1Test" in the frame is 0XBB, and the "NUM" value of the three consecutive frames received from each terminal station is continuous, then the continuity test of terminal station 1 ends, and no continuity test frames are sent, and the state is changed to data communication; If terminal station 2 receives the continuity test frame sent by terminal station 1, terminal station 3, terminal station 4, and terminal station 5, if "Ter2Test" in the frame is 0XBB, and the "NUM" value of 3 consecutive frames received from each terminal station is continuous, the continuity test of terminal station 2 ends, and it will no longer send continuity test frames and switch to data communication state; the reception and processing methods of continuity test frames by terminal station 3, terminal station 4, and terminal station 5 are the same as those of terminal station 1; (2.4) If the continuity test frame number "NUM" sent by terminal station 1, terminal station 2, terminal station 3, terminal station 4 or terminal station 5 exceeds 300 and does not switch to the data communication state, the continuity test fails and the communication ends.

9. The high-availability satellite communication system according to claim 1, characterized in that: The central station has a polling mechanism for the terminal stations in the network, as follows: (1) When the terminal station is in the centralized waiting state for access to the network, the central station sends polling signaling to the terminal station on the main TDM frequency and the backup TDM frequency at regular intervals. The format is: {"NUM":1; "CU":0XAA;}, where "CU" is the unique address of the terminal station, and "NUM" is the signaling sequence number, ranging from 1 to 65535. Each CU address is used independently and cyclically; the polling signaling interval of the same terminal station shall not be less than 3s; (2) After receiving the polling command sent by the central station, the terminal station sends a polling response signaling on the control ALOHA frequency according to the terminal station status. The format is: {"NUM":1; "CU":0XAA; "STATUS":"Communicating"; "FRQ_SEND":14000000000Hz; "FRQ_RECEIVE":12000000000Hz;}, where "NUM" is consistent with the received polling command "NUM", and "STATUS" is the status of the terminal station at this time, including "centralized waiting status" and "communication status". If "STATUS" is "communication", the signaling should include the transmitting frequency "FRQ_SEND" and the receiving frequency "FRQ_RECEIVE" to report the communication status; (3) After receiving the polling response signaling from the terminal station, the central station first confirms whether the polling response is valid based on "NUM" and "CU". If "NUM" and "CU" are the same as the sent polling signaling, the polling response is valid; then it determines whether the status of the terminal station is consistent with the information of the central station. If they are consistent, it continues to perform other operations; if they are inconsistent, it updates the information of the central station; if "NUM" and "CU" are inconsistent with the sent polling signaling, the polling response is invalid; (4) If the central station sends three consecutive frames of polling signaling with the value "NUM" and does not receive a related polling response or the response is invalid, it is considered that the terminal is abnormally shut down or faulty, and the status information of the terminal station related to the central station is changed to "exit network". At the same time, a "exit network" status control command is sent to this terminal station.

10. A high-availability satellite communication method, characterized in that: The method is based on the high-availability satellite communication system according to any one of claims 1 to 9, and is specifically as follows: The central station is used for network management of satellite communication systems and control of communication processes; the network management server configures the central channel control equipment into main TDM channels, backup TDM channels, control ALOHA channels, business ALOHA channels, and backup equipment as needed; the central channel control equipment has a channel self-check function to determine the operating status and whether there is a fault, including two forms: power-on channel self-check and operating channel self-check; The terminal station is used for network management agency and business communications, including short message services, voice services and data services; the terminal channel control equipment realizes information interaction with the central station and is also used for the transmission of burst business information; the multi-channel modem realizes point-to-point and cluster business communications; the short message service has a confirmation response mechanism to determine whether the short message is sent and received successfully; the data services of point-to-point and cluster business communication modes have a continuity test process before the communication link is established, and the formal business communication can only start after verifying that the satellite channel is unobstructed.

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