A multi-path end-to-end transmission system based on air-to-ground communication and application method

Abstract

The present invention relates to a multi-path end-to-end transmission system and application method based on air-to-ground communication, and belongs to the field of air-to-ground broadband communication. The system includes: an airborne server, which is responsible for negotiating with airborne users to establish connections, and scheduling user service flows to multiple channels through the calculation results of the algorithm of the load balancing unit; an air-to-ground channel simulation system, which configures channel parameters and displays the real-time performance of the channel from the interface, and provides an API for the airborne server, and sends channel status information to the load synchronization module; a ground gateway server, which receives service data streams from multiple channels, decrypts the data and updates the key held by the current channel, and reorganizes the data according to the SFN field of the protocol and forwards it to the ground user. The present invention adaptively schedules data through the load synchronization module to prevent channel congestion, and ensures data transmission security through the key update unit, thereby ensuring the stable transmission of airborne service data streams.

Description

Technical Field

[0001] The invention belongs to the field of air-to-ground broadband communication, and relates to a multi-path end-to-end transmission system based on air-to-ground communication and an application method. Background Art

[0002] In the face of the large amount of data in future civil aviation ground communications, if a single channel is used to transmit user data streams, the air-ground channel is prone to congestion. In order to meet the needs of passengers, this requires that future aviation communication systems have high-bandwidth, high-speed, and low-latency data communication capabilities.

[0003] At present, there are three main modes for providing in-flight Internet access in civil aviation:

[0004] (1) Using satellite links to establish connections with ground networks, that is, satellite communication technology, is currently a solution for achieving broadband wireless communication between air and ground.

[0005] (2) ATG technology. The air-to-ground (ATG) broadband access system based on ground base stations has the main working principle of deploying a dedicated base station on the land system to establish a communication link with the ATG equipment installed on the aircraft, thereby connecting to the network.

[0006] (3) Aircraft wireless LAN: Use a tablet computer or laptop to log in to the aircraft's LAN and browse local resources within the LAN.

[0007] In addition, when users frequently access the Internet through inflight WiFi, a large amount of user data is bound to be generated. Among these data, there will be some sensitive data, such as user personal privacy, data generated by business exchanges, administrative data flows, etc., which users do not want to be known to the outside world. However, since wireless information is transmitted in a broadcast medium (air), the data is susceptible to interception or tampering. The national GB / T 22239-2019 stipulates that data exchange related to civil aviation communication transmission should use encryption and authentication technology to achieve functions such as identity authentication, access control and data encryption transmission. Therefore, it is necessary to encrypt the data messages generated in air-to-ground communications.

[0008] At present, the most commonly used encryption algorithms in academia are classified into symmetric algorithms, asymmetric algorithms, and irreversible algorithms. RSA asymmetric encryption requires a long public key transmission, which is not suitable for link data encryption for air-to-ground communication systems with limited bandwidth and high latency. For symmetric encryption (DES / triple DES), there is no forward secrecy, and attackers can capture data streams and analyze the data from any time. Although most scholars have proposed a hybrid encryption method of asymmetric encryption identity certificates and symmetric encryption link data to securely manage civil aviation user data, the problems of certificate management and key hosting remain to be solved. Summary of the invention

[0009] In view of this, the purpose of the present invention is to provide a multi-path end-to-end transmission system based on air-to-ground communication. By building a multi-channel proxy server platform, while improving the throughput of air-to-ground communication, a lower complexity method is adopted to enhance the confidentiality of user data, thereby protecting user privacy while ensuring the user's Internet experience.

[0010] In order to achieve the above object, the present invention provides the following technical solutions:

[0011] Solution 1: A multi-path end-to-end transmission system based on air-ground communication, including an airborne server, a ground gateway server, and an air-ground channel simulation system;

[0012] The onboard server includes an event-driven module I, a data processing module I, a load synchronization module and a data cache module I; wherein,

[0013] The event-driven module I includes a negotiation processing unit, a TCP / DUP agent unit I and an event registration unit I; the negotiation processing unit is responsible for processing the user's request access information and establishing a connection with the onboard server; the TCP / DUP agent unit I selects the type of multi-channel transmission protocol according to the user's negotiation information; the event registration unit I is responsible for managing all user access and forwarding events, as well as special events from the channel simulation system;

[0014] The data processing module I includes a data scheduling unit, a key generation unit and a data forwarding unit I; the data scheduling unit will perform user data message scheduling operations before data transmission according to the channel state parameters obtained from the load synchronization module; the key generation unit determines whether to use encrypted transmission or unencrypted transmission through the negotiation field parsed by the upper layer, and periodically updates the local key; the data forwarding unit I is responsible for storing the user's data message in the data buffer area of ​​the corresponding channel according to the user information, and waiting for the data to be sent;

[0015] The load synchronization module includes a parameter receiving unit I, a load balancing unit and a synchronization updating unit I; the parameter receiving unit I is used to receive the channel quality parameters from the ground gateway server; the load balancing unit calculates the data transmission parameter values ​​of each channel through the load distribution algorithm and sends it to the data slicing unit; the synchronization updating unit I is used to update the currently reserved sub-stream allocation result in real time;

[0016] The data buffer module I includes a receiving buffer unit I and a sending buffer unit I; the receiving buffer unit I is responsible for temporarily storing each received user data and channel parameter data in the corresponding buffer area waiting for the corresponding unit to process; the sending buffer unit I is responsible for sending the data in the sending buffer area through different channels;

[0017] The ground gateway server includes an event-driven module II, a data processing module II, a parameter synchronization module and a data cache module II; wherein the event-driven module II includes an address resolution unit, a TCP / DUP proxy unit II and an event registration unit II; the address resolution unit needs to resolve the destination IP according to the access request message sent by the airborne server and establish a connection with the destination; the functions of the remaining units are the same as those of the units belonging to the above-mentioned airborne server. The TCP / DUP proxy unit II and the event registration unit II have the same functions as the TCP / DUP proxy unit I and the event registration unit I of the airborne server, respectively.

[0018] The data processing module II includes a data reassembly unit, a key updating unit and a data forwarding unit II; the data reassembly unit receives data from multiple channels and reassembles the data into a complete message according to the protocol SFN field; the key updating unit has a similar function to the key generation unit of the airborne server, but does not generate an initial key; the data forwarding unit II has the same function as the data forwarding unit I of the airborne server;

[0019] The parameter synchronization module includes a parameter receiving unit II and a synchronization updating unit; the parameter receiving unit II will receive the channel state information from the air-ground channel simulation system and calculate the completed data slice values ​​of each channel; the synchronization updating unit will periodically obtain the data scheduling information sent by the airborne server and complete the update;

[0020] The data cache module II includes a receiving cache unit II and a sending cache unit II; the receiving cache unit II is responsible for temporarily storing the received ground gateway information in the corresponding cache area waiting for the corresponding unit to process; the sending cache unit II is responsible for sending the data in the sending cache area through different channels;

[0021] The air-to-ground channel simulation system includes a human-computer interaction unit, a data processing unit and a data forwarding unit; the human-computer interaction unit is responsible for sending current avionics parameters, such as longitude and latitude, rainfall, etc., to the data processing unit; the data processing unit is responsible for calculating the quality parameters of the current wireless channel based on the input avionics parameters; the data forwarding unit is used to forward the wireless channel status information to the airborne server.

[0022] Furthermore, the transmission system connects the airborne terminal with the ground gateway, and under the control of avionics parameters, forwards data through the airborne server and the ground gateway server, thereby realizing a network architecture based on end-to-end secure transmission from the airborne terminal to the ground gateway.

[0023] Furthermore, the data scheduling unit calculates the results of the channel state information, slices the user message into message segments in proportion, and then forwards the message segments from the corresponding channel.

[0024] Furthermore, the data reassembly unit reassembles the message segments forwarded through multiple channels into a complete message according to the SFN number carried by the transmission message protocol.

[0025] Furthermore, after initially generating the symmetric key, the key updating unit will regenerate a new key according to the data transmitted through the corresponding channel and the initial key, and the generation formula is:

[0026]

[0027] in, is the newly generated symmetric key for channel n, msg_segment[0:32] is the first 16 bytes of the data segment to be sent on each channel, is the symmetric key of the channel, and md5(·) represents the MD5 digest algorithm.

[0028] Furthermore, the load synchronization unit divides the channel quality parameters from the ground gateway server received by the parameter receiving unit I into multiple message segments according to the load distribution algorithm, so as to improve the total throughput of the transmission system in unit time;

[0029] The load distribution algorithm calculation formula is:

[0030]

[0031]

[0032] Where σ represents the maximum throughput, S p represents the subflow assigned to path p, and P represents the path set; is the effective loss rate of path p, is the transmission loss rate, is the overdue loss rate; E(D p ) represents the average end-to-end delay, ρ p The available source of the classic M / G / 1 queue model can be estimated as ρ based on the latest observation of the path state information. p =v p 'RTT p / 2,v p is the transmission rate of path p; μ p and v p They represent the lossless bandwidth and residual bandwidth of the current path p respectively; the transmission interval between packets is represented by Δw p And are independent of each other; MTU indicates the data packet size.

[0033] Solution 2: An application method of a multi-path end-to-end transmission system based on air-to-ground communication, specifically comprising the following steps:

[0034] S1: Build an airborne server on the airborne side and a ground gateway server on the ground base station side;

[0035] S2: The airborne user accesses the airborne server through the negotiation authentication message. After the airborne server establishes a connection with the user, it will establish an end-to-end connection with the ground gateway server based on the currently available communication channel. Then, it will encapsulate the received user data in a specific message format through multiple channels and forward it to the ground gateway server.

[0036] S3: The ground gateway server receives the data message segments sent from multiple channels, decapsulates the user message, and reassembles it according to the serial SFN number; then, the reassembled user message is forwarded to the target user.

[0037] Further, step S2 specifically includes the following steps:

[0038] S21: The airborne server determines the transmission protocol and encryption method according to the negotiated authentication message, and randomly generates the initial key for each channel;

[0039] S22: The airborne server establishes a multi-channel connection with the ground gateway server, and forwards the destination IP field carried in the negotiation authentication message to the ground gateway server;

[0040] S23: Split the user's transmitted data stream in proportion according to the congestion-aware load distribution algorithm and store it in the buffer area of ​​the corresponding channel; each channel will encrypt the data using AES symmetric encryption according to the randomly generated encryption flag; after the encryption of the user data message segment in the buffer area of ​​each channel is completed, take the first 32 bytes of the transmitted data and couple them with the initial key according to the specified polynomial, and use the MD5 algorithm to generate a new key and vector iv and update them;

[0041] S24: After the ciphertext of each channel is encapsulated according to the protocol rules, the data is sent to the ground gateway server through multiple channels.

[0042] Further, step S3 specifically includes the following steps:

[0043] S31: After receiving the destination address IP sent by the onboard server, each channel will establish a corresponding connection with the corresponding destination IP;

[0044] S32: After receiving the data, the ground gateway server needs to complete two functions. First, parse the current message according to the transmission message protocol format, determine the current RAND number, and then select the key held by the corresponding channel to parse the current message. At the same time, according to the currently parsed plaintext data, update the key held by the corresponding channel. Then, according to the SFN number, put the parsed plaintext into the corresponding cache queue. Once the END signal is parsed, the data reorganization process will be initiated.

[0045] After receiving the data, the ground gateway server parses the encryption flag to determine whether AES decryption is required; if necessary, the decrypted data is placed in the cache until the data completion flag is parsed; similarly, the original key is used to couple the first 32 bytes of the received user data with a polynomial to keep it consistent with the key held by the onboard server; the data in the cache is reorganized into a completed data message and then sent to the destination address.

[0046] The beneficial effect of the present invention is that the present invention reallocates the received user data streams according to the quality of the current multiple channels. The algorithm distributes the user data to each channel in proportion for transmission and encrypts it by coupling multiple channels, which effectively increases the system throughput while ensuring that the user privacy is not leaked, thus realizing the secure transmission of user data.

[0047] Other advantages, objectives and features of the present invention will be described in the following description to some extent, and to some extent, will be obvious to those skilled in the art based on the following examination and study, or can be taught from the practice of the present invention. The objectives and other advantages of the present invention can be realized and obtained through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention will be described in detail below in conjunction with the accompanying drawings, wherein:

[0049] Figure 1 This is a network architecture diagram of the air-to-ground communication end-to-end secure transmission system of the present invention;

[0050] Figure 2 It is a schematic diagram of the module flow of the end-to-end secure transmission system for air-to-ground communication of the present invention;

[0051] Figure 3 This is a schematic diagram of the negotiation authentication message format;

[0052] Figure 4 This is a schematic diagram of the data transmission message format;

[0053] Figure 5 This is the structural diagram of the hybrid encryption model;

[0054] Figure 6 The present invention is a flow chart of an application method of an end-to-end secure transmission system for air-to-ground communication. DETAILED DESCRIPTION

[0055] The following describes the embodiments of the present invention by specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the illustrations provided in the following embodiments only illustrate the basic concept of the present invention in a schematic manner, and the following embodiments and features in the embodiments can be combined with each other without conflict.

[0056] See also Figure 1 to Figure 6 , Figure 1 The figure shows a multi-path end-to-end transmission system based on air-to-ground communication. Figure 1 In this embodiment, the channel simulation system is used to simulate the change of satellite communication channel quality. Based on the DVB-RCS2 satellite return link protocol, the modulation mode and coding rate are adaptively selected, and fed back to the airborne user terminal and the ground gateway through synchronous Ethernet, so as to realize the simulated transmission of the air-to-ground communication scene on the ground side. The overall system architecture includes: airborne user terminal, airborne server, channel simulation system, ground gateway server and ground user terminal.

[0057] Among them, the airborne server, as the negotiation access end, will initialize the key according to the system parameters after the deployment is completed, and wait for the airborne user end to send a negotiation request message. After receiving the request negotiation message from the airborne user end, the airborne server will parse the negotiation request message and determine the protocol and encryption method to be used for this transmission. The airborne server will then determine the number of currently available paths, establish an end-to-end connection with the ground gateway server, and randomly select a channel to send the IP address and port of the destination end to the ground gateway server. After that, it will enter the wait_data state and wait for the user to send a data stream.

[0058] When the ground gateway server receives the connection request message sent by the airborne server, it will parse the destination IP and establish an end-to-end connection with it. At the same time, the ground gateway server will feedback the current delay, packet loss and other information of each channel to the airborne server so that the load synchronization module of the airborne server can make load distribution decisions.

[0059] The load synchronization module includes a load balancing unit and a synchronization update unit. The load balancing unit receives the path parameters from the ground gateway server and splits the data stream from the ground gateway server into multiple segments according to the load distribution algorithm to achieve the purpose of increasing the total throughput of the transmission system per unit time. The calculation formula of the load distribution algorithm is as follows:

[0060]

[0061]

[0062] Where σ represents the maximum throughput, S p represents the subflow assigned to path p, and P represents the path set; is the effective loss rate of path p, is the transmission loss rate, is the overdue loss rate; E(D p ) represents the average end-to-end delay, ρ p The available source of the classic M / G / 1 queue model can be estimated as ρ based on the latest observation of the path state information. p =v p 'RTT p / 2,v p is the transmission rate of path p; μ p and v p They represent the lossless bandwidth and residual bandwidth of the current path p respectively; the transmission interval between packets is represented by Δw p And are independent of each other; MTU indicates the data packet size.

[0063] In addition, in order to estimate the current communication path information more effectively, the available bandwidth of the communication path can be characterized as:

[0064]

[0065] where w p Represents the congestion window size at the current moment, and RTT p Represents the round-trip delay.

[0066] And set the rate of change of each iteration on path p to ΔS p , then the next sub-flow allocation can be expressed as S p +ΔS p In order to calculate the rate of change of each iteration, the link growth algorithm is used to estimate the increment each time:

[0067]

[0068]

[0069] See also Figure 2 In this embodiment, the airborne server needs to adjust the proportion of data segments that need to be sent in each cache queue according to the channel parameters fed back by the ground gateway server. At the same time, both the airborne service end and the ground gateway server need to put the user connection into the timeout queue so that it can be automatically disconnected after not sending data streams for a long time to prevent the number of connections from being occupied. When the airborne / ground gateway server receives data from the user, it will first pass through the load balancing unit, and segment the user message by transmitting the calculated channel data transmission parameter value to the data slicing unit. The message segments will then be encapsulated according to a fixed protocol. The I / O multiplexing mode adopted by the entire server architecture will be selected according to the configuration file. In addition, the entire system selects a suitable module for processing through event-driven, for example, when there is data in the cache area, a POLL_OUT event is triggered, and receiving data will trigger a POLL_IN event, etc.

[0070] The present invention is based on a multi-channel end-to-end secure transmission system for air-to-ground communication, by deploying an airborne server on the airborne user side and a ground gateway server on the ground base station side, to achieve multi-channel transmission between the airborne terminal and the ground network. The application method of the system specifically includes the following steps:

[0071] S1: Build a ground gateway server on the ground gateway side and an airborne server on the airborne side.

[0072] S2: The user passes Figure 3The negotiation authentication message shown in the figure is connected to the local server. After the airborne server establishes a connection with the user, it will establish an end-to-end connection with the ground gateway server based on the currently available communication channel. Then, the received user data will be transmitted through multiple channels as shown in the figure. Figure 4 After encapsulation in the specific message format shown, it is forwarded to the ground gateway server. The specific steps include:

[0073] S21: The airborne server determines the transmission protocol and whether the transmission needs to be encrypted based on the negotiated authentication message. If encryption is required, the initial key for each channel will be randomly generated.

[0074] S22: The airborne server establishes a multi-channel connection with the ground gateway server, and forwards the destination IP field carried in the negotiation authentication message to the remote proxy server.

[0075] S23: Split the user's data stream in proportion according to the congestion-aware load distribution algorithm and store it in the corresponding channel's buffer. Each channel will encrypt the data using AES symmetric encryption according to the randomly generated encryption flag. When the encryption of the user data message segment in each channel's buffer is completed, take the first 32 bytes of the transmitted data and the initial key as follows: Figure 5 The coupling is performed in the manner shown, and a new key and vector iv are generated and updated using the MD5 algorithm.

[0076] S24: After the ciphertext of each channel is encapsulated according to the protocol rules, the data is sent to the ground gateway server through multiple channels.

[0077] S3: The ground gateway server receives the data message segments sent from multiple channels, decapsulates the user message according to the protocol, and reassembles it according to the sub-stream sequence number SFN. Then, the reassembled user message is forwarded to the target user. The specific steps include:

[0078] S31: After receiving the destination address IP sent by the onboard server, each channel will establish a corresponding connection with the corresponding destination IP.

[0079] S32: After receiving the data, the ground gateway server needs to complete two functions. First, parse the current message according to the transmission message protocol format, determine the current RAND number, and then select the key held by the corresponding channel to parse the current message. At the same time, according to the currently parsed plaintext data, update the key held by the corresponding channel. Then, according to the SFN number, put the parsed plaintext into the corresponding cache queue. Once the END signal is parsed, the data reorganization process will be initiated.

[0080] See also Figure 6Based on the above-designed end-to-end secure transmission system based on air-to-ground communication, the embodiment of the present invention also designs an application method for unidirectional data transmission, including the following steps:

[0081] S1: Configure the configuration file of the airborne / ground gateway server, specify the initial system parameters, initial password, encryption method, multi-channel enable flag, and the IP address and port number of the airborne / ground gateway server.

[0082] S2: The channel simulation system interface configures environmental parameters and system parameters, and uploads the channel status information to the parameter receiving unit of the load synchronization module of the airborne / ground gateway server;

[0083] S3: The onboard user terminal starts to initiate a negotiation access request to the onboard server. The onboard server parses the current negotiation message and establishes a connection with the user negotiation terminal after determining that the protocol format is met.

[0084] S4: The airborne server parses the negotiation message, determines the transmission protocol and encryption method to be adopted, and randomly selects an available channel to send the negotiation message carrying the destination address IP and port number to the ground gateway server.

[0085] S5: After receiving the negotiation message, the ground gateway server parses the destination address and establishes a connection with the destination. At the same time, the data synchronization module obtains the current channel status information from the API provided by the channel simulation system and inputs it into the load synchronization unit as source data.

[0086] S6: The onboard user terminal starts to transmit data stream, the onboard server receives the POLL_IN event, queries the hash table of the corresponding management connection, finds the corresponding user fd identifier, puts the received user data stream into the corresponding buffer area, and then processes it through the data scheduling unit of the data synchronization module.

[0087] S61: After each user negotiates to access the onboard server, the corresponding fd information and destination address number will be recorded in the hash table, so that the corresponding destination address number can be queried when sending data streams and carried in the transmitted message.

[0088] S62: After the data stream is sent to the data scheduling unit of the airborne server, the data scheduling unit will obtain the calculation results of the load synchronization module in real time, and split the data stream into fixed-ratio message segments according to the algorithm results. If encryption is required, each message segment is coupled and encrypted using the key corresponding to the current channel, and then a suitable channel is selected for transmission.

[0089] S7: After receiving the data stream forwarded by the airborne server, the ground gateway server reassembles the data stream according to the parsed message key fields. When the data stream is reassembled, the data is also stored and managed using the hash table and sent to the cache area, waiting for the kernel to enable the data sending module to send the data in the cache area to the destination.

[0090] S71: Data from the onboard server will be based on Figure 2 The SFN field and the user fd identifier of the protocol message shown store the segmented data stream in the corresponding user reassembly area, waiting for the completion of the data stream transmission.

[0091] S72: Each user hash table has n queues. If and only if there are data domain nodes in the queues, the reception of this user data flow is completed. At this time, the queues are polled and traversed, and each queue node is taken out in turn to reorganize into the original data message.

[0092] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the purpose and scope of the technical solution, which should be included in the scope of the claims of the present invention.

Claims

1. A multi-path end-to-end transmission system based on air-to-ground communication, characterized in that: The transmission system includes an airborne server, a ground gateway server and an air-to-ground channel simulation system; The onboard server includes an event-driven module I, a data processing module I, a load synchronization module and a data cache module I; wherein, The event-driven module I includes a negotiation processing unit, a TCP / DUP agent unit I and an event registration unit I; the negotiation processing unit is responsible for processing the user's request access information and establishing a connection with the onboard server; the TCP / DUP agent unit I selects the multi-channel transmission protocol type according to the user's negotiation information; the event registration unit I is responsible for managing all user access and forwarding events, as well as special events from the channel simulation system; The data processing module I includes a data scheduling unit, a key generation unit and a data forwarding unit I; the data scheduling unit will perform user data message scheduling operations before data transmission according to the channel state parameters obtained from the load synchronization module; the key generation unit determines whether to use encrypted transmission or unencrypted transmission through the negotiation field parsed by the upper layer, and periodically updates the local key; the data forwarding unit I is responsible for storing the user's data message in the data buffer area of ​​the corresponding channel according to the user information, and waiting for the data to be sent; The load synchronization module includes a parameter receiving unit I, a load balancing unit and a synchronization updating unit I; the parameter receiving unit I is used to receive the channel quality parameters from the ground gateway server; the load balancing unit calculates the data transmission parameter values ​​of each channel through the load distribution algorithm and sends it to the data slicing unit; the synchronization updating unit I is used to update the currently reserved sub-stream allocation result in real time; The data buffer module I includes a receiving buffer unit I and a sending buffer unit I; the receiving buffer unit I is responsible for temporarily storing each received user data and channel parameter data in the corresponding buffer area waiting for the corresponding unit to process; the sending buffer unit I is responsible for sending the data in the sending buffer area through different channels; The ground gateway server includes an event-driven module II, a data processing module II, a parameter synchronization module and a data cache module II; wherein the event-driven module II includes an address resolution unit, a TCP / DUP proxy unit II and an event registration unit II; the address resolution unit resolves the destination IP according to the access request message sent by the airborne server and establishes a connection with the destination; the TCP / DUP proxy unit II and the event registration unit II have the same functions as the TCP / DUP proxy unit I and the event registration unit I of the airborne server respectively; The data processing module II includes a data reassembly unit, a key updating unit and a data forwarding unit II; the data reassembly unit receives data from multiple channels and reassembles the data into a complete message according to the protocol SFN field; the key updating unit has a similar function to the key generation unit of the airborne server, but does not generate an initial key; the data forwarding unit II has the same function as the data forwarding unit I of the airborne server; The parameter synchronization module includes a parameter receiving unit II and a synchronization updating unit; the parameter receiving unit II will receive the channel state information from the air-ground channel simulation system and calculate the completed data slice values ​​of each channel; the synchronization updating unit will periodically obtain the data scheduling information sent by the airborne server and complete the update; The data cache module II includes a receiving cache unit II and a sending cache unit II; the receiving cache unit II is responsible for temporarily storing the received ground gateway information in the corresponding cache area waiting for the corresponding unit to process; the sending cache unit II is responsible for sending the data in the sending cache area through different channels; The air-to-ground channel simulation system includes a human-computer interaction unit, a data processing unit and a data forwarding unit; the human-computer interaction unit is responsible for sending the current avionics parameters to the data processing unit; the data processing unit is responsible for calculating the quality parameters of the current wireless channel based on the incoming avionics parameters; the data forwarding unit is used to forward the wireless channel status information to the airborne server.

2. The multipath end-to-end transmission system according to claim 1, characterized in that: The transmission system connects the airborne terminal with the ground gateway. Under the control of avionics parameters, data is forwarded through the airborne server and the ground gateway server, realizing a network architecture based on end-to-end secure transmission from the airborne terminal to the ground gateway.

3. The multi-path end-to-end transmission system according to claim 1, characterized in that: The data scheduling unit calculates the results of the channel status information, slices the user message into message segments in proportion, and then forwards the message from the corresponding channel.

4. The multi-path end-to-end transmission system according to claim 1, characterized in that: The data reassembly unit reassembles the message segments forwarded through multiple channels into a complete message according to the SFN number carried by the transmission message protocol.

5. The multi-path end-to-end transmission system according to claim 1, characterized in that: After initially generating the symmetric key, the key update unit will regenerate a new key based on the data transmitted by the corresponding channel and the initial key. The generation formula is: in, is the newly generated symmetric key for channel n, msg_segment[0:32] is the first 16 bytes of the data segment to be sent on each channel, is the symmetric key of the channel, and md5(·) represents the MD5 digest algorithm.

6. The multi-path end-to-end transmission system according to claim 1, characterized in that: The load synchronization module divides the channel quality parameters from the ground gateway server received by the parameter receiving unit I into multiple message segments according to the load distribution algorithm, so as to achieve the purpose of improving the total throughput of the transmission system per unit time; The load distribution algorithm calculation formula is: Where σ represents the maximum throughput, S p represents the subflow assigned to path p, and P represents the path set; is the effective loss rate of path p, is the transmission loss rate, is the overdue loss rate; E(D p ) represents the average end-to-end delay, ρ p is the available source of the classic M / G / 1 queue model, and its value is estimated based on the latest observation of the path state information; p is the transmission rate of path p; μ p and v p They represent the lossless bandwidth and residual bandwidth of the current path p respectively; the transmission interval between packets is represented by Δw p And are independent of each other; MTU indicates the data packet size.

7. The multipath end-to-end transmission system according to any one of claims 1 to 6, characterized in that: The application method of the system specifically includes the following steps: S1: Build an airborne server on the airborne side and a ground gateway server on the ground base station side; S2: The airborne user accesses the airborne server through the negotiation authentication message. After the airborne server establishes a connection with the user, it will establish an end-to-end connection with the ground gateway server based on the currently available communication channel. Then, it will encapsulate the received user data in a specific message format through multiple channels and forward it to the ground gateway server. S3: The ground gateway server receives the data message segments sent from multiple channels, decapsulates the user message, and reassembles it according to the serial SFN number; then, the reassembled user message is forwarded to the target user.

8. The multi-path end-to-end transmission system according to claim 7, characterized in that: Step S2 specifically includes the following steps: S21: The airborne server determines the transmission protocol and encryption method according to the negotiated authentication message, and randomly generates the initial key for each channel; S22: The airborne server establishes a multi-channel connection with the ground gateway server, and forwards the destination IP field carried in the negotiation authentication message to the ground gateway server; S23: Split the user's transmitted data stream in proportion according to the congestion-aware load distribution algorithm and store it in the buffer area of ​​the corresponding channel; each channel will encrypt the data using AES symmetric encryption according to the randomly generated encryption flag; after the encryption of the user data message segment in the buffer area of ​​each channel is completed, take the first 32 bytes of the transmitted data and couple them with the initial key according to the specified polynomial, and use the MD5 algorithm to generate a new key and vector iv and update them; S24: After the ciphertext of each channel is encapsulated according to the protocol rules, the data is sent to the ground gateway server through multiple channels.

9. The multi-path end-to-end transmission system according to claim 7, characterized in that: Step S3 specifically includes the following steps: S31: After receiving the destination address IP sent by the onboard server, each channel will establish a corresponding connection with the corresponding destination IP; S32: After receiving the data, the ground gateway server parses the encryption flag to determine whether AES decryption is required; if necessary, the decrypted data is placed in the cache until the data completion flag is parsed; similarly, the original key is used to couple the first 32 bytes of the received user data with a polynomial to keep it consistent with the key held by the onboard server; and the data in the cache is reorganized into a completed data message, which is then sent to the destination address.

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