Efficient and reliable satellite Internet transmission method based on segmentation proxy

Abstract

The present invention discloses a method for efficient and reliable satellite Internet transmission based on segmented proxy, which mainly solves the problems of poor performance and reliability of existing technologies in satellite communications. Its implementation scheme is: establishing a segmented QUIC connection of a geographically gridded low-orbit satellite network, and adding a connection mapping relationship on the overhead satellite; the satellite covering the terminal user determines the status of the connection by checking the message sent by the terminal; the overhead satellite encapsulates and transmits the message according to the connection mapping relationship based on the data transmission status, and returns an immediate response to the source terminal as the destination terminal; when the overhead satellite moves to the point where it can no longer maintain coverage of the current grid, the business information is migrated to the satellite that is about to take over to switch and continue data transmission until the source terminal completes the business transmission and closes the connection between the source terminal and the destination terminal. The present invention reduces the impact of low-orbit satellite switching on link performance, improves the link establishment speed and resource utilization of satellite Internet, and can be used for satellite communication links.

Description

Technical Field

[0001] The present invention belongs to the field of network communication technology, and in particular relates to a satellite Internet transmission method, which can be used in satellite communication links to effectively improve the performance and reliability of satellite Internet data transmission. Background Art

[0002] Satellite Internet has become an important part of the future 6G network. It will supplement the ground network and provide supplementary coverage and enhanced services for space-based users, air-based users, remote areas, and sea users.

[0003] When the TCP protocol, which is widely used in terrestrial networks, is applied to satellite networks, the link throughput drops significantly and the transmission performance is greatly affected due to the significant differences between the characteristics of the satellite's transmission channel and the terrestrial network link.

[0004] Without considering packet loss, the TCP throughput T can be approximately calculated using the following formula:

[0005]

[0006] Where B is the link bandwidth, typically measured in bits per second (bps); W is the TCP window size; RTT is the round-trip time (RTT), the time it takes for a packet to be sent, received, and acknowledged, typically measured in seconds; and L is the packet size (bits). L / B represents the transmission time for a packet. This formula assumes that the TCP window is fully open (i.e., the window size W is significantly greater than 1) and that the link is stable with no packet loss. In this case, TCP throughput is primarily limited by the bandwidth B and the round-trip time (RTT).

[0007] Compared to terrestrial networks, satellite communication systems experience greater link transmission latency, and TCP throughput is limited by the sliding window. TCP requires a large send window to fully utilize bandwidth, but the standard TCP protocol has a maximum window size of 64KB, which undoubtedly reduces throughput. Furthermore, the bit error rate in satellite links is much higher than that in terrestrial networks. Standard TCP treats all bit errors as network congestion and uses a slow-start algorithm to reduce the send window. This not only fails to alleviate congestion, but actually worsens satellite link performance.

[0008] In response to the many problems of satellite links, researchers have proposed a large number of improvement plans. Among them, the reliable transmission protocol solution based on segmented TCP technology is widely used. According to the differences in the intermediate segment protocols, it can be further subdivided into segmented reliable transmission protocol solutions based on TCP protocol optimization and segmented reliable transmission protocol solutions based on other protocols.

[0009] Segmented TCP technology, also known as Performance Enhancement Proxy (PEP), transparently implements a TCP proxy within an end-to-end connection, intercepting the original TCP connection and replacing it with a transmission method more appropriate for the link. The proxy server assumes some of the tasks typically performed by the communicating parties, including data reception and acknowledgment transmission. When the proxy detects packet loss or transmission errors, it proactively requests retransmission from the source rather than waiting for feedback from the destination. This mechanism effectively improves the overall performance of TCP connections and enhances data transmission efficiency.

[0010] A well-known open source example is PEPsal, introduced by Carlo Caini et al. in the article "PEPsal: a Performance Enhancing Proxy designed for TCP satellite connections[C]." Vehicular Technology Conference, 2006. VTC2006-Spring. IEEE 63rd vol. 6.2006:2607-2611. PEPsal is a performance-enhancing proxy designed specifically for TCP connections over satellite links. It optimizes TCP connections on satellite links by isolating the long RTT and random packet loss issues of satellite links through TCP segmentation. It also uses TCP Hybla, a TCP enhancement mechanism designed specifically for satellite networks, as the transport protocol for satellite links, thereby improving link utilization. However, because this method does not modify the packet loss recovery mechanism, Hybla still suffers from problems such as a sudden drop in the congestion window and TCP header blocking delays when packets are lost.

[0011] The intermediate segment can also use a completely different protocol. In recent research, the QUIC (Quick UDP Internet Connection) protocol has been used to implement TCP PEP. Proposed and deployed by Google, the QUIC protocol is a new transport layer protocol based on the User Datagram Protocol (UDP). It adds congestion control algorithms and retransmission-based loss recovery mechanisms, providing a reliable and ordered byte stream interface for the application layer. The QUIC protocol can achieve orderly and reliable stream transmission in user mode, and add features such as secure transmission and multiplexing to the protocol; when establishing a connection, the QUIC protocol can reduce the handshake steps compared to the TCP protocol. Since the underlying layer of the QUIC protocol is the UDP protocol, there is no need for a three-way handshake to establish a connection, which can reduce the handshake time required by the TCP protocol; in terms of sending data, the QUIC protocol makes improvements on the SYN sequence number of the TCP protocol, and uses a monotonically increasing PN to more accurately calculate the RTT; compared with the protocol header length limit of the TCP protocol, the QUIC data packet can contain more ACK ranges instead of retransmitting the data packet, avoiding invalid repeated transmission, and speeding up the data retransmission speed in a network environment with a high packet loss rate; the QUIC protocol supports the client to switch to a different network address while ensuring that the connection will not be interrupted.

[0012] In their paper "QUIC-proxy-based architecture for satellite communication to enhance a 5G scenario," presented at the 2019 International Symposium on Networks, Computers and Communications (ISNCC), Istanbul, Turkey, 2019, pp. 1-6, doi:10.1109 / ISNCC.2019.8909181, A. Abdelsalam et al. explored a QUIC proxy-based satellite communication architecture to improve performance in 5G scenarios. By setting up a QUIC proxy, they split the end-to-end connection into three segments: a TCP connection between the client and the QUIC client proxy, a QUIC connection between the QUIC client proxy and the QUIC server proxy, and a TCP connection between the QUIC server proxy and the server. This approach significantly reduces the transmission latency of small objects and exhibits greater resilience during link switching, allowing data transmission to continue without user intervention. However, this approach still suffers from the following two issues:

[0013] First, the issue of satellite handover in low-orbit satellite scenarios is not considered. Unlike high-orbit satellites, which are stationary relative to the Earth, low-orbit satellites are more dynamic, causing their relative positions to constantly change with respect to ground stations or terminals. This characteristic results in more frequent handovers between low-orbit satellites and users. Satellite handovers can lead to unstable or even interrupted connections, impacting not only the user's communication experience but also forcing ongoing data transmission to be paused or restarted, increasing packet loss and affecting the performance of the entire transmission protocol.

[0014] Secondly, in real-world environments, satellites must provide services to all users within their coverage area. Excessive TCP connections inevitably impact transmission performance. Due to the TCP protocol's connection establishment mechanism, excessive TCP connections lead to frequent handshakes, which consume significant network resources and increase latency. Maintaining these connections requires regular heartbeat packets, which inevitably increases network traffic and leads to congestion. These factors, combined, reduce the transmission efficiency of the entire satellite communication system, impacting the user experience. Summary of the Invention

[0015] The purpose of the present invention is to address the deficiencies of the above-mentioned existing technologies and propose an efficient and reliable satellite Internet transmission method based on segmented proxy to reduce packet loss caused by switching, ensure the link performance of the satellite network during switching between low-orbit satellites, and at the same time simplify the satellite-to-ground connection, reduce resource consumption, and improve the transmission efficiency of the system.

[0016] The technical idea to achieve the above purpose is: through the establishment of a QUIC-based segmentation proxy mechanism on the satellite, the segmented transmission mechanism is combined with the characteristics of the QUIC protocol, and a client gateway is configured on the low-orbit satellite to build a QUIC link for communication, thereby improving transmission efficiency, reducing latency, and ensuring link performance during satellite switching; by introducing a geographic grid, the various segments of the satellite network are more closely linked, thereby enhancing the stability of the satellite network during satellite switching; through the pre-processing of data packets by the QUIC proxy and the pre-built public inter-satellite QUIC link, the waste of resources caused by frequent connection establishment is avoided, and the link utilization rate is improved.

[0017] According to the above ideas, the technical solution of the present invention includes the following steps:

[0018] (1) Establishing a segmented QUIC connection for a geo-gridized LEO satellite network:

[0019] (1a) Dividing the Earth's surface into geographic grids based on longitude and latitude, such that all terminals in each geographic grid are within the communication coverage of the same low-orbit satellite, i.e., an overhead satellite, establishing a QUIC connection between all low-orbit satellites, and generating a first QUIC connection ID number;

[0020] (1b) Generate a second QUIC connection ID number and complete the connection establishment process between the terminal and the destination terminal:

[0021] The terminal within the grid initiates a connection establishment request, covers the terminal user's satellite intercept request message, and forwards it to the overhead satellite of the destination terminal, and finally forwards it to the destination terminal;

[0022] After receiving the request message, the destination terminal generates and returns a confirmation message, which is forwarded back to the terminal via the overhead satellite, and a mapping relationship is established with the first QUIC connection ID number at the overhead satellite of the destination terminal;

[0023] The terminal's overhead satellite adds this mapping relationship to the mapping table during the process of forwarding the confirmation message;

[0024] The terminal receives the confirmation message and generates a second QUIC connection ID number based on the information therein, completing the connection establishment process;

[0025] (2) The satellite covering the terminal user intercepts the message sent by the terminal in this grid to the destination terminal, and determines whether to establish a connection by checking whether the second QUIC connection ID number contained in the request message is mapped to the first QUIC connection ID number:

[0026] If no mapping relationship exists, the connection is not established and the process returns to step (1b);

[0027] If a mapping exists, the connection has been established. Check whether the message contains the end connection flag:

[0028] If not, data transmission is performed and step (3) is executed;

[0029] If yes, go to step (5);

[0030] (3) The source terminal and the destination terminal transmit data via a segmented QUIC connection over a geo-gridized low-orbit satellite network:

[0031] The overhead satellite covering the source terminal intercepts the message sent from the source terminal to the destination terminal in the grid, replaces the destination terminal in sending a response message to the source terminal, and encapsulates the message and forwards it to the overhead satellite covering the destination terminal according to the mapping relationship;

[0032] After receiving the encapsulated message, the overhead satellite covering the destination terminal returns a confirmation message to the overhead satellite covering the source terminal and forwards the initial message to the destination terminal;

[0033] After receiving the message, the destination terminal sends a confirmation message to the overhead satellite covering the destination terminal, completing the data transmission;

[0034] (4) When the overhead satellite moves to a point where it can no longer cover the current grid, the service information is transferred to the satellite that is about to take over and a handover is performed:

[0035] The current overhead satellite transmits the status information, mapping table, and cache data of all its active connections to the handover satellite via the inter-satellite link. After receiving the service information message, the handover satellite updates its own service table and mapping table.

[0036] For messages that have been received by the currently overhead satellite and have entered the inter-satellite link for transmission, they will continue to be transmitted according to the link before the handover;

[0037] For messages that have been received by the current overhead satellite but have not yet entered the inter-satellite link for transmission, and messages that have not yet been received by the current overhead satellite, the switching satellite will continue to transmit after receiving the sequence number and buffer of the current overhead satellite.

[0038] (5) After the source terminal completes the service transmission, it closes the connection between the source terminal and the destination terminal.

[0039] Compared with the prior art, the present invention has the following advantages:

[0040] First, the present invention combines QUIC technology with segmented reliable transmission technology. In a satellite Internet environment, it can not only ensure the advantages of reliable connection and short link establishment delay, but also achieve high resource utilization in a long-delay link environment.

[0041] Second, the present invention transfers the basis for associating users with QUIC connections from highly mobile low-orbit satellites to a fixed geographic grid. By using the geographic grid, it achieves more stable management of user connections with the network, reducing the impact of low-orbit satellite switching on transmission performance. At the same time, by utilizing the connection migration characteristics in the QUIC protocol, it effectively reduces the delay when the communication link is switched due to the migration of low-orbit satellites, thereby improving network performance.

[0042] Third, the present invention aggregates and classifies the data of each user terminal within the same geographic grid unit, and then forwards and transmits them in sequence through a public QUIC connection, reducing the resources occupied by establishing separate connections and improving link utilization. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 This is a schematic diagram of the geographic gridded low-orbit satellite network scenario used in the present invention.

[0044] Figure 2 It is an implementation flow chart of the present invention;

[0045] Figure 3 is a schematic diagram of establishing a transmission connection between a terminal and a destination terminal in the present invention;

[0046] Figure 4 This is a schematic diagram of message transmission in the present invention;

[0047] Figure 5 Schematic diagram of link switching scenario of low-orbit satellite in the present invention;

[0048] Figure 6 Schematic diagram of closing a connection in the present invention. DETAILED DESCRIPTION

[0049] As a crucial component of future 6G networks, satellite internet will complement terrestrial networks, providing supplementary coverage and enhanced services for space-based users, airborne users, remote areas, and users on the ocean. However, due to the typical characteristics of satellite internet, such as extended link latency, high bit error rates, highly dynamic network topology, and asymmetric uplink and downlink bandwidth, directly adopting the TCP protocol, a reliable transmission protocol widely used in terrestrial networks, for satellite internet will lead to low network resource utilization, prone to interruption of reliable transmission paths, and extended wait times for end-to-end reliable transmission link establishment.

[0050] Therefore, satellite internet urgently requires an adaptive transmission mechanism to improve end-to-end transmission performance. This example designs a transmission method that combines QUIC technology with segmented reliable transmission technology. By replacing the traditional TCP transmission protocol or the improved TCP protocol with pre-established QUIC connections between terminals and low-orbit satellites, and between low-orbit satellites, the advantages of the QUIC protocol are utilized to reduce link establishment time and improve performance.

[0051] Terminals are divided according to geographic grids, and messages whose target terminals are in the same geographic grid unit are merged for transmission, reducing the number of links that the agent needs to maintain.

[0052] Taking into account the switching problems caused by the mobility of low-orbit satellites, QUIC connections are established between low-orbit satellites in advance. When the satellite-to-ground link switches, the connection migration mechanism of the QUIC protocol is used to greatly save the link establishment time.

[0053] The specific embodiments of the present invention are further described in detail below with reference to the accompanying drawings.

[0054] Reference Figure 1 This example uses a geo-gridized low-orbit satellite network scenario, including a geo-grid, a satellite constellation, and user terminals.

[0055] Geographic grid, a grid system that divides the Earth's surface into longitude and latitude, with each terminal device within the grid being within the communication coverage of a single low-orbit satellite;

[0056] A satellite constellation is a group of low-orbit satellites that orbit the Earth to provide communications services. These satellites are distributed at varying intervals and patterns to ensure global coverage.

[0057] User terminal: refers to the device used by users, such as mobile phones, tablets or other communication devices, which can receive and send signals from satellites.

[0058] Reference Figure 2 , the implementation steps of this example are as follows:

[0059] Step 1: Establish a segmented QUIC connection to the geo-gridified low-orbit satellite network.

[0060] 1.1) Establish QUIC connections between all low-orbit satellites based on a geographic grid:

[0061] 1.1.1) Divide the Earth's surface into geographic grids based on longitude and latitude, ensuring that all terminals in each grid are within the communication coverage of the same low-orbit satellite, or overhead satellite;

[0062] 1.1.2) Establish QUIC connections between all low-orbit satellites based on the geographic grid and generate the first QUIC connection ID number;

[0063] 1.2) Establish a connection between the terminal and the destination terminal:

[0064] Reference Figure 3 , the specific implementation of this step is as follows:

[0065] 1.2.1) The terminal within the grid initiates a connection establishment request. The satellite covering the terminal user intercepts the request message and forwards it to the destination terminal's overhead satellite, and ultimately forwards it to the destination terminal. The request message includes: the client's initial parameters and TLS handshake information, where the initial parameters include the protocol version number, random connection ID number, and packet sequence number;

[0066] 1.2.2) After receiving the request message, the destination terminal generates and returns a confirmation message, which is forwarded back to the terminal via the overhead satellite, and a mapping relationship is established with the first QUIC connection ID number at the destination terminal's overhead satellite; wherein the confirmation message generated and returned by the destination terminal to the terminal includes: server-side parameters and TLS handshake information, wherein the server-side parameters include the protocol version number and parameters for confirming the connection; the TLS handshake information includes a key exchange value obtained using the Diffie-Hellman key exchange algorithm;

[0067] 1.2.3) The terminal's overhead satellite adds this mapping relationship to the mapping table during the process of forwarding the confirmation message;

[0068] 1.2.4) The terminal receives the confirmation message and generates a second QUIC connection ID number based on the information therein, completing the connection establishment process. At this point, the segmented QUIC connection of the geographic grid low-orbit satellite network is established.

[0069] Step 2: The satellite covering the terminal user determines the type of message sent by the terminal.

[0070] 2.1) Satellites covering terminal users intercept messages sent to destination terminals by terminals within their grid;

[0071] 2.2) Determine whether to establish a connection by checking whether the second QUIC connection ID number contained in the request message is mapped to the first QUIC connection ID number:

[0072] If no mapping relationship exists, the connection is not established and the process returns to step (1.2).

[0073] If there is a mapping relationship, execute step 2.3);

[0074] 2.3) Continue to determine whether the message contains the end connection mark:

[0075] If not, data transmission is performed and step 3 is executed;

[0076] If yes, go to step 5.

[0077] In step 3, the source terminal and the destination terminal transmit data through a segmented QUIC connection of the geo-gridized low-orbit satellite network.

[0078] Reference Figure 4 , the specific implementation of this step is as follows:

[0079] 3.1) A satellite passing overhead that covers the source terminal intercepts the message sent from the source terminal to the destination terminal within its grid, and sends a response message to the source terminal on behalf of the destination terminal. The response message is a response message generated by the passing satellite in the identity of the destination terminal in response to the connection request message;

[0080] 3.2) The overhead satellite covering the source terminal encapsulates the message based on the mapping relationship and forwards it to the overhead satellite covering the destination terminal. Specifically, the overhead satellite covering the source terminal first uses the message sent by the source terminal as an upper-layer message, then encapsulates it based on the mapping relationship added in step (1.2.3), and forwards it to the overhead satellite covering the destination terminal.

[0081] 3.3) After receiving the encapsulated message, the overhead satellite covering the destination terminal returns a confirmation message to the overhead satellite covering the source terminal. The confirmation message is a direct response to the message encapsulated and forwarded by the overhead satellite covering the source terminal.

[0082] 3.4) The overhead satellite covering the destination terminal forwards the initial message to the destination terminal; the initial message is the original data message restored after the overhead satellite covering the destination terminal decapsulates the encapsulated message received;

[0083] 3.5) After receiving the message, the destination terminal sends a confirmation message to the overhead satellite covering the destination terminal, completing the data transmission.

[0084] Step 4: When the overhead satellite moves to a point where it can no longer cover the current grid, the service information is transferred to the satellite that is about to take over for switching.

[0085] Reference Figure 5 , the specific implementation of this step is as follows:

[0086] 4.1) The currently passing satellite transmits the status information, mapping tables, and cached data of all its active connections to the incoming handover satellite via an inter-satellite link. The status information of the currently passing satellite's connections includes the connection status information of the currently passing satellite with all terminals within its coverage grid and with other satellites. Both types of connection status information contain connection identifiers, terminal information, connection status, security information, routing information, and configuration parameters.

[0087] 4.2) After receiving the service information message, the switching satellite updates its own service form and mapping table;

[0088] 4.3) For messages that have been received by the currently overhead satellite and have entered the inter-satellite link for transmission, they will continue to be transmitted according to the link before the handover;

[0089] 4.4) For messages that have been received by the current overhead satellite but have not yet entered the inter-satellite link for transmission and messages that have not yet been received by the current overhead satellite, the switching satellite will continue to transmit after receiving the sequence number and cache of the current overhead satellite.

[0090] Step 5: After completing the service transmission, the source terminal closes the connection between the source terminal and the destination terminal.

[0091] Reference Figure 6 , the specific implementation of this step is as follows:

[0092] 5.1) After the source terminal completes the service transmission, it sends a connection termination message containing a connection termination identifier. The connection termination message includes an error code and a connection termination reason.

[0093] 5.2) The source terminal's overhead satellite receives the connection termination message and returns a confirmation message to the source terminal. After the buffered data is sent, the message is forwarded to the overhead satellite covering the destination terminal based on the mapping relationship;

[0094] 5.3) After receiving the connection termination message, the overhead satellite covering the destination terminal returns a confirmation message to the overhead satellite covering the source terminal. After the buffered data is sent, the connection termination message is forwarded to the destination terminal.

[0095] 5.4) After receiving the connection termination message, the destination terminal sends a confirmation connection termination message to the overhead satellite covering the destination terminal, completing the connection release of the destination terminal;

[0096] 5.5) The overhead satellite covering the destination terminal receives and forwards the connection termination confirmation message to the overhead satellite covering the source terminal, completing the connection release of the overhead satellite covering the destination terminal and deleting the corresponding mapping information in the mapping table;

[0097] 5.6) The overhead satellite covering the source terminal receives the connection termination confirmation message, completes the connection release of the overhead satellite covering the source terminal, removes the corresponding mapping relationship from the mapping table, and forwards the connection termination confirmation message to the source terminal;

[0098] 5.7) The source terminal receives the confirmation message of connection termination and releases all resources related to the connection, completing the connection closing process.

[0099] The above description is only a specific example of the present invention and does not constitute any limitation to the present invention. Obviously, for professionals in this field, after understanding the content and principles of the present invention, it is possible to make various modifications and changes in form and details without departing from the principles and structure of the present invention. However, these modifications and changes based on the ideas of the present invention are still within the scope of protection of the claims of the present invention.

[0100] It should be noted that the step numbers in the specification and claims of the present invention are only for a clear description of the embodiments of the present invention and for ease of understanding, and the order of the step numbers is not limited.

Claims

1. A satellite Internet efficient and reliable transmission method based on segment proxy, characterized in that: The steps include: (1) Establishing a segmented QUIC connection for a geo-gridized LEO satellite network: (1a) Dividing the Earth's surface into geographic grids based on longitude and latitude, such that all terminals in each geographic grid are within the communication coverage of the same low-orbit satellite, i.e., an overhead satellite, establishing a QUIC connection between all low-orbit satellites, and generating a first QUIC connection ID number; (1b) Generate a second QUIC connection ID number and complete the connection establishment process between the terminal and the destination terminal: The terminal within the grid initiates a connection establishment request, covers the terminal user's satellite intercept request message, and forwards it to the overhead satellite of the destination terminal, and finally forwards it to the destination terminal; After receiving the request message, the destination terminal generates and returns a confirmation message, which is forwarded back to the terminal via the overhead satellite, and a mapping relationship is established with the first QUIC connection ID number at the overhead satellite of the destination terminal; The terminal's overhead satellite adds this mapping relationship to the mapping table during the process of forwarding the confirmation message; The terminal receives the confirmation message and generates a second QUIC connection ID number based on the information therein, completing the connection establishment process; (2) The satellite covering the terminal user intercepts the message sent by the terminal in this grid to the destination terminal, and determines whether to establish a connection by checking whether the second QUIC connection ID number contained in the request message is mapped to the first QUIC connection ID number: If no mapping relationship exists, the connection is not established and the process returns to step (1b); If a mapping exists, the connection has been established. Check whether the message contains the end connection flag: If not, data transmission is performed and step (3) is executed; If yes, go to step (5); (3) The source terminal and the destination terminal transmit data via a segmented QUIC connection over a geo-gridized low-orbit satellite network: The overhead satellite covering the source terminal intercepts the message sent from the source terminal to the destination terminal in the grid, replaces the destination terminal in sending a response message to the source terminal, and encapsulates the message and forwards it to the overhead satellite covering the destination terminal according to the mapping relationship; After receiving the encapsulated message, the overhead satellite covering the destination terminal returns a confirmation message to the overhead satellite covering the source terminal and forwards the initial message to the destination terminal; After receiving the message, the destination terminal sends a confirmation message to the overhead satellite covering the destination terminal, completing the data transmission; (4) When the overhead satellite moves to a point where it can no longer cover the current grid, the service information is transferred to the satellite that is about to take over and a handover is performed: The current overhead satellite transmits the status information, mapping table, and cache data of all its active connections to the handover satellite via the inter-satellite link. After receiving the service information message, the handover satellite updates its own service table and mapping table. For messages that have been received by the currently overhead satellite and have entered the inter-satellite link for transmission, they will continue to be transmitted according to the link before the handover; For messages that have been received by the current overhead satellite but have not yet entered the inter-satellite link for transmission, and messages that have not yet been received by the current overhead satellite, the switching satellite will continue to transmit after receiving the sequence number and buffer of the current overhead satellite. (5) After the source terminal completes the service transmission, it closes the connection between the source terminal and the destination terminal.

2. The method according to claim 1, characterized in that The satellite interception request message covering the terminal user in step (1b) includes: the initial parameters of the client and TLS handshake information, wherein the initial parameters include the protocol version number, the random connection ID number and the packet sequence number.

3. The method according to claim 1, characterized in that After the destination terminal receives the request message in step (1b), the confirmation message generated includes: server-side parameters and TLS handshake information, the server-side parameters include the protocol version number and parameters for confirming the connection; the TLS handshake information includes the key exchange value obtained using the Diffie-Hellman key exchange algorithm.

4. The method according to claim 1, wherein In step (3), the response message sent by the overhead satellite to the source terminal instead of the destination terminal is generated by the overhead satellite as the destination terminal to respond to the connection request message.

5. The method according to claim 1, wherein In step (3), the overhead satellite covering the source terminal encapsulates the message and forwards it to the overhead satellite covering the destination terminal. The overhead satellite covering the source terminal first uses the message sent by the source terminal as an upper-layer message, then encapsulates it according to the mapping relationship generated in step (1), and forwards it to the overhead satellite covering the destination terminal.

6. The method according to claim 1, characterized in that The confirmation message returned by the overhead satellite covering the destination terminal to the overhead satellite covering the source terminal in step (3) is a direct response confirmation to the message encapsulated and forwarded by the overhead satellite covering the source terminal.

7. The method according to claim 1, characterized in that The initial message forwarded to the destination terminal by the overhead satellite covering the destination terminal in step (3) is the original data message restored after the overhead satellite covering the destination terminal decapsulates the encapsulated message received.

8. The method according to claim 1, characterized in that The status information of the overhead satellite connection in step (4) includes the connection status information of the current overhead satellite with all terminals in the geographical grid it covers and the connection status information with other satellites. Both types of connection status information contain a connection identifier, terminal information, connection status, security information, routing information and configuration parameters.

9. The method according to claim 1, characterized in that In step (5), the source terminal closes the connection between the source terminal and the destination terminal after completing the service transmission, which is achieved as follows: After the source terminal completes the service transmission, it sends a connection termination message containing a connection termination identifier. The connection termination message includes an error code and a connection termination reason. The source terminal's overhead satellite receives the connection termination message and returns a confirmation message to the source terminal. After the buffered data is sent, the message is forwarded to the overhead satellite covering the destination terminal according to the mapping relationship. After receiving the connection termination message, the overhead satellite covering the destination terminal returns a confirmation message to the overhead satellite covering the source terminal, and forwards the connection termination message to the destination terminal after the buffered data is sent. After receiving the connection termination message, the destination terminal sends a confirmation connection termination message to the overhead satellite covering the destination terminal, completing the connection release of the destination terminal; The overhead satellite covering the destination terminal receives and forwards the connection termination confirmation message to the overhead satellite covering the source terminal, completes the connection release of the overhead satellite covering the destination terminal, and deletes the corresponding mapping information in the mapping table; The overhead satellite covering the source terminal receives the connection termination confirmation message, completes the connection release of the overhead satellite covering the source terminal, removes the corresponding mapping relationship from the mapping table, and forwards the connection termination confirmation message to the source terminal; The source terminal receives the confirmation end connection message and releases all resources related to the connection, completing the connection closing process.

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