A reliable communication system based on publish / subscribe mode in a star-ground weak network environment

Abstract

The application discloses a reliable communication system based on a publish-subscribe mode in a star-ground weak network environment, aiming at the problems of high round-trip delay, limited link bandwidth, high instantaneous packet loss rate, link being easily affected by shielding and switching and the like existing in the data transmission process between a low-orbit satellite and a ground station, a publish-subscribe model is introduced in an application layer to realize business logic decoupling, and is deeply fused with an underlying enhanced QUIC transmission protocol, combined with message persistence, breakpoint resuming, forward error correction and connection migration and the like mechanisms, under the condition of unstable link, quality fluctuation and communication interruption, stable, orderly, complete and safe transmission of business data can still be guaranteed, and high availability and continuity of star-ground communication tasks under a weak network condition are realized.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of satellite communication, and in particular to a reliable communication system based on a publish-subscribe mode in a weak satellite-terrestrial network environment. BACKGROUND

[0002] In recent years, with the continuous expansion of satellite communication applications in the fields of emergency communication, remote monitoring, polar scientific exploration, and ocean exploration, satellite-terrestrial links have become an important support for many key tasks. However, due to the physical characteristics and operating environment of space links, satellite-terrestrial communication generally exhibits weak network characteristics: the link round-trip time is high and fluctuates significantly, is easily affected by obstructions, weather conditions, and electromagnetic interference, resulting in burst packet loss, errors, and jitter; at the same time, the link bandwidth is limited and the available time within the communication window is limited, and congestion and transmission delays are likely to occur during peak traffic periods.

[0003] In the existing communication protocol system, traditional TCP will cause a significant decrease in throughput due to timeout retransmission and window contraction under high latency (RTT up to hundreds of milliseconds to several seconds), high packet loss link, long connection establishment time, and slow recovery; UDP has low delay, but lacks reliability and order guarantee, and requires application layer to implement packet loss detection, retransmission, and out-of-order processing, increasing system implementation complexity. QUIC protocol, with 0-RTT connection establishment, multiplexing, and adaptive congestion control, performs well in weak network environments on the Internet, but still has limitations in satellite-terrestrial links: lack of efficient message persistence and breakpoint resume mechanism after link interruption, and session continuity is difficult to guarantee in frequent link switching process, affecting the stable operation of the business.

[0004] On the other hand, satellite-terrestrial communication services have very high requirements for data transmission reliability, integrity, and continuity. Task scheduling instructions, on-board application data, and business load data often cannot be lost or out of order, otherwise it may cause task interruption or even irreversible data loss. The existing point-to-point transmission mode often needs additional application layer processing of state synchronization, packet loss recovery, and order reorganization under weak network conditions, which not only increases the development difficulty, but also reduces the adaptability and scalability of the system.

[0005] In summary, the existing technology still has problems such as low transmission efficiency, insufficient session continuity, and imperfect reliability guarantee in the satellite-terrestrial weak network environment, and there is an urgent need for a technical solution that combines a high-efficiency and reliable underlying transmission protocol with a flexible decoupling mechanism at the upper layer to continuously, stably, and efficiently complete the transmission and delivery of task data under conditions of unstable links, fluctuating latency, and limited bandwidth. SUMMARY

[0006] To solve the problems of link instability, low transmission efficiency, poor service continuity and insufficient reliability in the prior art under the star-ground weak network environment, the application provides a reliable communication system based on a publish-subscribe mode under a star-ground weak network environment. The scheme combines an enhanced QUIC protocol with a message persistence mechanism, and realizes decoupling of the service layer and the transmission layer through the publish-subscribe mode, so as to guarantee stable transmission and delivery of task data under the condition of high latency, high packet loss and easily interrupted link.

[0007] To achieve the above object, the application provides a reliable communication system based on a publish-subscribe mode under a star-ground weak network environment, which comprises a star message queue terminal and a ground message queue terminal with a symmetrical architecture, and the two terminals establish an end-to-end encrypted communication channel based on an enhanced QUIC protocol through a weak network link; the star message queue terminal and the ground message queue terminal each comprise a publish-subscribe service module, a message persistence module, a link state monitoring module and a retransmission and recovery module.

[0008] The publish-subscribe service module is used for topic management, subscription relationship maintenance and permission control of business data based on a topic-driven message distribution mechanism.

[0009] The message persistence module is used for locally persistently storing data packets to be sent and received data packets that have not been confirmed, and recording unique identifiers and offsets of the messages.

[0010] The link state monitoring module is used for real-time collection and analysis of link performance indicators.

[0011] The retransmission and recovery module is used for dynamically adjusting a sending window, a retransmission interval and a priority scheduling strategy based on the link state monitoring result; and triggering a retransmission mechanism when data packet loss, disorder or link recovery is detected.

[0012] Further, the publish-subscribe service module is responsible for defining, registering and managing various business topics in terms of topic management; and the topics are classified according to the type, purpose or key attributes of the source of the business data.

[0013] Further, the publish-subscribe service module is responsible for establishing an association between a data consumer and a corresponding topic to form a subscription record after the data consumer expresses an attention diagram for a specific topic to the publish-subscribe service module in terms of subscription relationship maintenance; the subscription record comprises identity information of the data consumer, a subscription time range and additional requirements of the data consumer for message format and content; and the publish-subscribe service module continuously tracks state changes of the data consumer, including suspension, recovery or cancellation operations of the subscription.

[0014] Further, the publish / subscribe service module formulates corresponding permission policies for different topics and operation types, including publishing, subscribing, and modifying subscription relationships, based on the user's role, authentication results, and the sensitivity level of the data.

[0015] Further, through the message persistence module and the link state monitoring module, unacknowledged messages are recorded when the link is interrupted, and breakpoint continuation and data retransmission are implemented based on the offset after the link is restored, avoiding message duplication and data loss.

[0016] Further, the link state monitoring results include link delay values, real-time packet loss rate statistics, dynamic estimation of available bandwidth, and quantitative indicators of link jitter.

[0017] Further, the retransmission and recovery module dynamically adjusts the sending window, including changing the size of the data sending window in real time according to the link state monitoring results; increasing the sending window when the link condition is good to improve transmission efficiency; and reducing the sending window when the link condition is poor to reduce the sending rate.

[0018] Dynamic adjustment of retransmission interval includes adjusting the retransmission interval based on link state monitoring results; extending the retransmission interval when the link delay is large or the packet loss rate is high; and shortening the retransmission interval when the link condition is good.

[0019] Dynamic adjustment of priority scheduling strategy includes dynamically adjusting the transmission priority of different data according to the link state and the importance and urgency of the business data.

[0020] Further, the enhanced QUIC protocol constructs an adaptive algorithm for the high delay, low bandwidth, and unstable characteristics of the satellite-ground link, continuously monitors the link delay, packet loss rate, and bandwidth estimate, and dynamically scales the congestion window; when the monitoring indicators deteriorate, the window index backtracks and enters a conservative growth phase, and when the indicators are better than the set threshold, the window gradually increases; the enhanced QUIC protocol expands the connection identifier and introduces a state snapshot mechanism to record unconfirmed data, windows, and key information in advance; at the moment of path failure, the snapshot is transferred to the new path through the migration token, allowing the receiving end to restore the transmission context without rehandshake, completing millisecond-level seamless switching; the enhanced QUIC protocol has a three-level packet loss recovery mechanism, first distinguishing random packet loss from burst packet loss using timestamps combined with sequence numbers, then implementing immediate retransmission for random packet loss and starting segmented forward error correction for burst packet loss, and after the link is restored, retransmitting all unconfirmed packets at once based on the snapshot; at the same time, the forward error correction coding rate is dynamically adjusted according to the real-time packet loss rate, with the redundancy increased when the error rate is high and the redundancy reduced when the error rate is low.

[0021] Further, under normal link conditions, the message interaction process of the ground message queue terminal as a publishing end and the on-board message queue terminal as a subscribing end is performed in the following timing sequence:

[0022] The ground application generates a message according to a service requirement, binds a unique topic identifier to the message, and publishes the service message to the ground message queue terminal through a standardized interface;

[0023] The ground message queue terminal registers the message and the corresponding topic relationship through a publishing and subscribing module, and stores the message persistently; when the link monitoring module detects that the space-ground link state is normal, an enhanced QUIC protocol stack is called to perform multiplexing, low-latency handshake, and congestion control optimization configuration;

[0024] End-to-end encryption is enabled, and the ground message queue terminal transmits the encrypted service message in the space-ground link through the enhanced QUIC protocol;

[0025] The on-board message queue terminal receives and decrypts the service message, and stores the message persistently; the on-board message queue terminal checks the subscription relationship, and distributes the message to a target on-board application;

[0026] The on-board application receives the message, performs service processing, and sends a reception confirmation to the on-board message queue terminal; the on-board message queue terminal sends feedback in the space-ground link through the enhanced QUIC protocol, and the on-board message queue terminal returns the confirmation to the ground message queue terminal;

[0027] After the ground message queue terminal receives the confirmation message, the persistent record is updated according to the offset and the confirmation state of the message, and the feedback of successful processing is notified to the ground application.

[0028] Further, under abnormal link conditions, the message interaction process of the ground message queue terminal as a publishing end and the on-board message queue terminal as a subscribing end is performed in the following timing sequence:

[0029] The ground application generates and binds a topic of a service message, and publishes the service message to the ground message queue terminal through an interface;

[0030] The ground message queue terminal registers a topic, and stores the message and the current transmission offset persistently;

[0031] End-to-end encryption is enabled, and the ground message queue terminal transmits the encrypted service message in the space-ground link through the enhanced QUIC protocol;

[0032] When the ground message queue terminal detects that the link quality decreases or is interrupted through the link monitoring module, it suspends message sending, records the link abnormal state and stores the message persistently; it enables the breakpoint resuming mechanism, keeps the unconfirmed part of the message and its offset information; when the link monitoring module detects that the link is restored, it calls the connection migration and multiplexing capability of the enhanced QUIC protocol to reestablish the transmission session without rehandshake; the ground message queue terminal resumes message transmission according to the recorded offset, and retransmits the unconfirmed message based on the fast recovery mechanism of the enhanced QUIC protocol;

[0033] The on-board message queue terminal receives the resumed message data, merges and completes the partial data cached previously, verifies the message integrity, and stores it persistently; the on-board message queue terminal resends the delayed message due to interruption to the on-board application, returns the confirmation information after the business processing is completed, and then transmits the recovery confirmation and feedback to the ground message queue terminal;

[0034] After the ground message queue terminal receives the final confirmation, it updates the local persistent state, generates a recovery completion notification, and feeds back the final business processing result to the ground application.

[0035] Compared with the prior art, the present application has the following beneficial effects:

[0036] Firstly, the present application adopts a publish / subscribe model to decouple the business application layer and the communication transmission layer; the business application only needs to complete the publish and subscribe operations of the message, without needing to care about the complex logic such as maintenance of the underlying link state, data retransmission and sequence recovery, thereby greatly reducing the application development and operation complexity and improving the overall engineering usability of the system;

[0037] Secondly, the architecture of the present application has good scalability and flexibility; with the help of the multi-topic management and filtering distribution mechanism of the message queue, concurrent access and processing of multiple businesses and multiple subscription ends can be supported, so as to meet the needs of star-ground businesses in different scenarios; as the network scale expands, the system can be smoothly expanded without introducing additional complex coupling relationships, thereby having the ability of long-term application and evolution;

[0038] Finally, the present application can realize end-to-end reliable closed-loop feedback; under normal link, the message is published by the ground end, transmitted through the link and processed by the on-board message queue, and finally the processing result feedback is returned to the ground application; under abnormal link, the on-board message queue will confirm to the ground end after recovery is completed, and the ground end will finally feed back the recovery completion notification and the business processing result to the application, so as to ensure that a complete and reliable business closed loop can be formed regardless of whether the link is in normal or abnormal state;

[0039] In summary, the application significantly improves the reliability, real-time performance and scalability of the satellite-ground communication system in a weak network environment by the cooperative design of the publish-subscribe mode, the enhanced QUIC protocol optimization and the persistent and breakpoint resume mechanism, and can effectively improve the business continuity and engineering application value, and has obvious innovation and practicality. BRIEF DESCRIPTION OF DRAWINGS

[0040] In order to more clearly illustrate the technical solutions in the embodiments of the application, the following will briefly introduce the drawings needed to be used in the embodiment description. Obviously, the drawings in the following description are only some embodiments of the application, and other drawings can also be obtained by those skilled in the art without creative labor under the premise of not paying the creative labor:

[0041] Figure 1 is the satellite-ground communication framework based on the publish-subscribe mode in the application;

[0042] Figure 2 is the satellite-ground normal link timing diagram based on the publish-subscribe mode in the application;

[0043] Figure 3 is the satellite-ground abnormal link timing diagram based on the publish-subscribe mode in the application. DETAILED DESCRIPTION

[0044] The application will be described in detail below with reference to the drawings. The features in the following embodiments and implementation manners can be combined with each other without conflict.

[0045] Reference Figure 1 , the application proposes a reliable communication system based on the publish-subscribe mode in a satellite-ground weak network environment, and the overall architecture is composed of a satellite message queue terminal and a ground message queue terminal. The satellite-ground system establishes an end-to-end encrypted communication channel based on the enhanced QUIC protocol through the weak network link, so as to cope with the complex environment of unstable link, high delay and high packet loss rate, and realize high-reliable and low-delay data transmission.

[0046] In the overall system, the satellite application component interacts with the ground message queue terminal through the satellite message queue terminal, and the ground application component interacts with the satellite message queue terminal through the ground message queue terminal. The satellite message queue terminal efficiently and reliably transmits messages to the ground message queue terminal based on the end-to-end encrypted channel of the link, and then provides them to the ground application component, and vice versa, so as to realize reliable information interaction between the satellite and the ground. The satellite and ground message queue terminals have symmetrical architecture and are composed of the following core modules:

[0047] Publish-Subscribe Service Module: This module is based on a Topic-driven message distribution mechanism and is responsible for topic management, subscription relationship maintenance, and permission control of business data.

[0048] The present application introduces a message passing mechanism based on the publish-subscribe mode in satellite-ground communication, and combines the low-latency handshake, multiplexing, connection migration and congestion control optimization of the enhanced QUIC protocol, effectively solving the problem of service interruption caused by easy packet loss, high latency and frequent link interruption of traditional TCP / UDP communication in weak network environment. Therefore, the present application can still maintain the stability and efficiency of the communication link under the condition of complex fluctuation of satellite-ground link.

[0049] Specifically, the publish-subscribe service module is responsible for defining, registering and managing various business topics in terms of topic management. These topics are scientifically classified according to the type, purpose or source of business data, such as "remote sensing image data", "weather observation information", "satellite state parameters" and other topics in the satellite communication scenario. Each topic has a clear identification and description, so that data producers and consumers can accurately understand and select.

[0050] In terms of subscription relationship maintenance, after the data consumer (such as an application component on the satellite or on the ground) expresses interest in a specific topic to the publish-subscribe service module, the module establishes an association between the data consumer and the corresponding topic, forming a subscription record. These records detail the consumer's identity information, subscription time range, and special requirements for message format, content, etc. At the same time, the module continuously tracks the state changes of the consumer, such as suspension, resumption or cancellation of subscription, to ensure the timeliness and accuracy of the subscription relationship. By maintaining accurate subscription relationships, the module lays a solid foundation for efficient message distribution, ensuring that business data can accurately and timely reach the truly needed consumers.

[0051] In terms of permission control, important guarantees are provided for the security of the system and the confidentiality of the data. The publish-subscribe service module formulates diverse permission policies for different topics and operation types (such as publishing, subscribing, modifying subscription relationships, etc.). These policies are customized based on user roles, authentication results, and data sensitivity levels. For example, for topics involving satellite key control parameters, only ground control centers or on-board management systems with specific authorization are allowed to publish and subscribe, while ordinary users are restricted from accessing. The implementation of permission control relies on the system's authentication and authorization mechanism, which strictly verifies the identity information and permission level of users to ensure that each user operates within the scope of their authorization, effectively preventing unauthorized access and data leakage and other security threats.

[0052] By decoupling data producers and consumers, the system gives the business process a high degree of flexibility and scalability. In the satellite-ground communication system, the satellite and the ground station are respectively the data producers and consumers, and their operation and evolution have relative independence. For example, as the business develops, different types of satellite payloads may be added to produce new types of business data, and the ground station may also deploy new application systems to process these data accordingly. In this case, the publish-subscribe service module enables new data producers and consumers to quickly and conveniently join the system without the need for large-scale modification of existing businesses and other components. The producer only needs to publish data to the corresponding topic according to the established specification, and the consumer subscribes to the relevant topic according to its business needs, and other parts of the system are almost unaffected, thereby greatly reducing the risk and cost of business changes and improving the adaptability and competitiveness of the entire system.

[0053] Message persistence module: used for local persistent storage of data packets to be sent and received but not yet confirmed, and records the unique identifier and offset of the message. When the link is interrupted, switched or quality is reduced, the system can resume transmission according to the offset to achieve seamless breakpoint continuation and repeated data detection, avoiding data loss and redundant transmission.

[0054] Link state monitoring module: by real-time collection and analysis of delay, packet loss rate, bandwidth, jitter and other key link performance indicators, it provides decision basis for subsequent transmission strategy adjustment. At the same time, this module can generate link quality trend data for system optimization and scheduling strategy update reference.

[0055] The present application can record unconfirmed messages when the link is interrupted, and implement breakpoint continuation and data retransmission based on the offset after the link is restored, avoiding message repeated transmission and data loss. This mechanism significantly improves the reliability of message delivery and the continuity of business processing.

[0056] Retransmission and recovery module: based on the key results provided by the link state monitoring module (including accurate link delay values, real-time packet loss rate statistics, dynamic estimation of available bandwidth, and quantitative indicators of link jitter), dynamically adjust the transmission window, retransmission interval and priority scheduling strategy.

[0057] Specifically, dynamically adjusting the sending window refers to changing the size of the data sending window in real time according to the link state monitoring results. The sending window, as a key parameter of flow control, its size directly affects the data transmission rate of the sender. When the link condition is good, for example, the delay is low, the packet loss rate is almost zero, the bandwidth is sufficient and the jitter is small, the system will appropriately increase the sending window. This enables the sender to send more data packets in a unit of time, thereby improving transmission efficiency, fully utilizing link resources, and reducing the problem of insufficient link utilization caused by too small sending window. On the contrary, if the link condition is not good, such as high packet loss rate or large delay, the system will quickly reduce the sending window to reduce the sending rate, avoid further exacerbation of link congestion, reduce the queuing waiting time of data packets in the link, reduce the risk of data packet loss, and ensure the stability of data transmission.

[0058] Dynamic adjustment of retransmission interval is a process of optimizing the retransmission mechanism for link conditions. In an undesirable network environment, data packet loss is inevitable. At this time, the retransmission mechanism becomes a key means to ensure data integrity. However, blind retransmission may exacerbate the congestion of the link, and even trigger a "retransmission storm". Therefore, the system scientifically adjusts the retransmission interval according to the link state monitoring results. When the link delay is large or the packet loss rate is high, the system will appropriately extend the retransmission interval. This provides a buffer time for the self-recovery of the link condition, reducing the additional pressure on the link caused by a large number of retransmissions in a short period of time. Conversely, when the link condition is good, the system will shorten the retransmission interval to recover the lost data faster and improve the response speed and overall performance of the system.

[0059] Dynamic adjustment of priority scheduling strategy is to ensure the priority transmission of critical business data in complex communication scenarios. The system will dynamically adjust the transmission priority of different data according to the link state and the importance, urgency and other attributes of business data. For example, in a satellite-ground communication system, the real-time attitude control data of the satellite has a higher priority than the general scientific experiment data. When the link resource is tight, the system will prioritize the transmission of such critical data. By reasonably allocating link resources and prioritizing the transmission of high-priority data, the risk of business can be minimized to ensure the smooth execution of critical tasks.

[0060] In the link recovery process, the system may face various complex situations. For example, when the link is restored after being interrupted due to the satellite entering the Earth's shadow area, or reconnected after a short communication interruption caused by ground station switching. At this time, the system needs to conduct a comprehensive data consistency check. Based on the previously recorded message offset and sequence information, the system can accurately locate the data packets that were not completed at the time of interruption, as well as the data segments that may have been lost due to the interruption. The fast retransmission mechanism is then initiated to quickly send these incomplete and lost data packets to the receiving end, filling in the data gaps and ensuring the integrity of the data stream. At the same time, the system will perform sequence verification on the received data packets, and if it finds that there is an out-of-order phenomenon, i.e., the data packets do not arrive at the receiving end in the order they were sent, it will immediately initiate a data rearrangement function to rearrange the out-of-order data packets to the correct order, ensuring the logical coherence of the data. In addition, to further enhance the integrity and accuracy of the data, the system will also use error correction algorithms to check and correct the data. This includes detecting and correcting bit errors caused by link interference and other factors, as well as recovering some lost data content through redundant information. Through this series of fast retransmission, data rearrangement, and error correction operations, the system can effectively deal with the data incompleteness and out-of-order problems after link recovery, ensuring that the receiving end ultimately obtains complete, ordered, and correct data streams.

[0061] The above modules work collaboratively under the support of the multiplexing, low-latency handshake, congestion control optimization, and connection migration features provided by the enhanced QUIC protocol, enabling the system to still achieve high-reliability, low-interruption-rate transmission of business data in weak network satellite-ground communication scenarios, while also having good scalability and adaptability.

[0062] It should be noted that the enhanced QUIC protocol discards the traditional QUIC general congestion control and constructs an adaptive algorithm targeting the high delay, low bandwidth, and unstable characteristics of satellite-ground links: continuously monitoring link delay, packet loss rate, and bandwidth estimate values to dynamically scale the congestion window; when the monitoring indicators deteriorate, the window index is rolled back and enters a conservative growth phase, and when the indicators are better than the set threshold, the window gradually increases, thereby avoiding overly conservative or aggressive transmission strategies and achieving high throughput and low jitter transmission under weak network conditions.

[0063] Given the frequent path changes caused by satellite motion and ground station beam switching, the enhanced QUIC protocol expands the connection identifier and introduces a state snapshot mechanism to pre-record unconfirmed data, window, and key information; at the moment of path failure, the snapshot is transferred to the new path through a migration token, allowing the receiving end to restore the transmission context without re-handshake, completing millisecond-level seamless switching and significantly shortening the data interruption time caused by network migration.

[0064] The enhanced version of the QUIC protocol adds a three-level packet loss recovery mechanism in the existing framework: first, the timestamp is combined with the sequence number to distinguish random packet loss from burst packet loss, then the immediate retransmission is implemented for random packet loss, the segment forward error correction (FEC) is started for burst packet loss, and after the link recovery, all unconfirmed packets are retransmitted once according to the snapshot; meanwhile, the FEC coding rate is dynamically adjusted according to the real-time packet loss rate, the redundancy is increased when the error code is high, and the redundancy is reduced when the error code is low, so as to balance the recovery ability and bandwidth efficiency, and reduce the number of retransmissions and time delay.

[0065] In the star-ground communication system based on the publish-subscribe mode, the message transmission direction can be divided into two typical modes: one is that the ground end is the publishing end and the on-board end is the subscribing end; the other is that the on-board end is the publishing end and the ground end is the subscribing end.

[0066] Due to the high symmetry of the communication mechanism in the protocol structure and the processing flow, the implementation principles of the two modes are consistent in terms of underlying data interaction, session management, reliable transmission control and the like, so only one of the modes can be analyzed in detail in the technical description. The present application takes the ground end as the publishing end and the on-board end as the subscribing end as an example to describe the complete working process of the system in the aspects of message generation, topic distribution, link transmission, persistent processing and reliability guarantee.

[0067] As shown in Figure 2 Under normal link conditions, the message interaction process of the star-ground communication system based on the publish-subscribe mode, with the ground end as the publishing end and the on-board end as the subscribing end, can be performed in the following time sequence:

[0068] 1. Business data generation and topic binding: the ground application (GndApp) generates messages according to business requirements and binds a unique topic identifier (Topic) to the messages to achieve targeted data distribution. The GndApp publishes business messages to the ground message queue terminal (GndMQ) through a standardized interface.

[0069] 2. Message registration and persistence: the publish-subscribe module of the GndMQ registers the message and the corresponding topic relationship, and stores the message persistently to ensure the reliability of subsequent transmission.

[0070] Link state detection and transmission scheduling: after the link state detection module of the GndMQ detects that the star-ground link state is normal, the enhanced QUIC protocol stack is called to perform multiplexing, low-latency handshake and congestion control optimization configuration.

[0071] 3. Message transmission: end-to-end encryption is enabled, and the GndMQ transmits the encrypted business messages in the star-ground link through the enhanced QUIC protocol.

[0072] 4. Message receiving and persistence: Satellite Message Queue (SatelliteMQ) receives and decrypts the business message, and stores it persistently to prevent data loss.

[0073] 5. Message distribution: SatelliteMQ distributes the message to the target satellite application after checking the subscription relationship.

[0074] 6. Business processing and confirmation: Satellite Application (SatelliteApp) receives the message and processes the business, and sends a receiving confirmation (i.e. processing completion feedback) to SatelliteMQ, which sends the feedback in the satellite-ground link through the enhanced QUIC protocol. SatelliteMQ returns the confirmation to GndMQ.

[0075] 7. After receiving the confirmation message, GndMQ updates the persistent record according to the message offset and confirmation status, and notifies the GndApp of the "processing success" feedback result, thereby completing the closed loop of message transmission and business processing.

[0076] Under the condition of link exception (such as interruption, quality fluctuation or high latency packet loss), the satellite-ground communication in the same mode will trigger the message persistence, breakpoint resume and retransmission mechanism, and the detailed timing of the interactive process is shown in Figure 3 as follows:

[0077] 1. Business data generation and theme binding: the ground application generates and binds the theme of the business message, and publishes it to GndMQ through the standardized interface.

[0078] 2. Message registration and persistence: GndMQ registers the theme and stores the message and its current transmission offset persistently.

[0079] 3. Message transmission: start end-to-end encryption, GndMQ transmits the encrypted business message in the satellite-ground link through the enhanced QUIC protocol.

[0080] 4. Link state monitoring: GndMQ detects that the link quality has decreased or interrupted through the link monitoring module, suspends message sending, and records the link exception state to the persistent storage.

[0081] Breakpoint resume preparation: GndMQ enables the breakpoint resume mechanism and keeps the unconfirmed part of the message and its offset information.

[0082] 5. Link recovery detection: when the link monitoring module detects that the link has recovered, GndMQ calls the connection migration and multiplexing capability of the enhanced QUIC protocol to re-establish the transmission session without re-handshake.

[0083] 6. Breakpoint resume and message recovery: GndMQ recovers message transmission according to recorded offset, retransmits unconfirmed messages based on enhanced QUIC protocol fast recovery mechanism, avoids sending confirmed parts repeatedly, and reduces transmission delay and bandwidth waste.

[0084] 7. Onboard reception and completion: SatelliteMQ receives resumed message data, merges and completes with previously cached partial data, verifies message integrity, and stores persistently.

[0085] 8. Message distribution and service processing: SatelliteMQ retransmits delayed messages due to interruption to onboard applications, and returns confirmation information (i.e. processing completion feedback) after service processing is completed. SatelliteMQ then transmits recovery confirmation and feedback back to GndMQ.

[0086] 9. After receiving the final confirmation from SatelliteMQ, GndMQ updates the local persistent state, generates a "recovery completion" notification, and feeds the final service processing result back to ground application GndApp, thereby ensuring that message transmission and processing still have end-to-end reliability and closed-loop nature even in abnormal link conditions.

[0087] The above examples are only used to illustrate the design idea and characteristics of the present application, and the purpose is to enable those skilled in the art to understand the content of the present application and implement it, and the protection scope of the present application is not limited to the above examples. Therefore, any equivalent changes or modifications made according to the principles and design ideas disclosed by the present application are within the protection scope of the present application.

Claims

1. A reliable communication system based on a publish-subscribe model in a weak satellite-to-ground network environment, characterized in that, The system includes an on-board message queue terminal and a ground message queue terminal with a symmetrical architecture. The two establish an end-to-end encrypted communication channel based on the enhanced QUIC protocol through a weak network link. Both the on-board message queue terminal and the ground message queue terminal include a publish-subscribe service module, a message persistence module, a link status monitoring module, and a retransmission and recovery module. The publish-subscribe service module is used for topic-driven message distribution mechanism and is responsible for topic management, subscription relationship maintenance and access control of business data. The message persistence module is used to locally persist and store data packets to be sent and data packets that have been received but not yet acknowledged, and to record the unique identifier and offset of the message. The link status monitoring module is used to collect and analyze link performance indicators in real time; The retransmission and recovery module is used to dynamically adjust the sending window, retransmission interval and priority scheduling strategy based on the link status monitoring results. A retransmission mechanism is triggered when packet loss, out-of-order delivery, or link recovery is detected. The enhanced QUIC protocol addresses the high latency, low bandwidth, and instability of satellite-to-ground links by constructing an adaptive algorithm. It continuously monitors link latency, packet loss rate, and bandwidth estimates, dynamically scaling the congestion window. When monitored indicators deteriorate, the window exponentially regresses and enters a conservative growth phase; when indicators exceed a set threshold, the window gradually increases. The enhanced QUIC protocol expands the connection identifier and introduces a state snapshot mechanism to pre-record unacknowledged data, window information, and key information. In the event of path failure, a migration token transmits the snapshot to the new path, allowing the receiving end to restore the transmission context without re-handshaking, achieving millisecond-level seamless switching. The enhanced QUIC protocol features a three-level packet loss recovery mechanism: first, it distinguishes between random and burst packet loss using timestamps and sequence numbers; then, it immediately retransmits random packet loss and initiates segmented forward error correction for burst packet loss; and finally, after link recovery, it quickly retransmits all unacknowledged packets based on the snapshot. Simultaneously, it dynamically adjusts the forward error correction coding rate according to the real-time packet loss rate, increasing redundancy during high error rates and decreasing redundancy during low error rates.

2. The reliable communication system based on publish-subscribe mode in a weak satellite-to-ground network environment according to claim 1, characterized in that, In terms of topic management, the publish / subscribe service module is responsible for defining, registering, and managing various business topics; these topics are classified according to key attributes such as the type, purpose, or source of the business data.

3. The reliable communication system based on publish-subscribe mode in a weak satellite-to-ground network environment according to claim 1, characterized in that, In terms of subscription relationship maintenance, after a data consumer expresses its interest in a specific topic to the publish-subscribe service module, the publish-subscribe service module associates the data consumer with the corresponding topic, forming a subscription record. The subscription record includes the data consumer's identity information, subscription time range, and any additional requirements regarding message format and content. At the same time, the publish-subscribe service module continuously tracks changes in the data consumer's status, including pause, resumption, or cancellation of subscriptions.

4. The reliable communication system based on publish-subscribe mode in a weak satellite-to-ground network environment according to claim 1, characterized in that, In terms of access control, the publish / subscribe service module formulates corresponding access policies based on user roles, authentication results, and data sensitivity levels for different topics and operation types, including publishing, subscribing, and modifying subscription relationships.

5. The reliable communication system based on publish-subscribe mode in a weak satellite-to-ground network environment according to claim 1, characterized in that, By using a message persistence module and a link status monitoring module, unacknowledged messages are recorded when the link is interrupted. After the link is restored, breakpoint resume and data resending are implemented based on the offset, avoiding message duplication and data loss.

6. The reliable communication system based on publish-subscribe mode in a weak satellite-to-ground network environment according to claim 1, characterized in that, The link status monitoring results include link latency values, real-time packet loss rate statistics, dynamic estimation of available bandwidth, and quantitative indicators of link jitter.

7. The reliable communication system based on publish-subscribe mode in a weak satellite-to-ground network environment according to claim 1, characterized in that, The retransmission and recovery module dynamically adjusts the sending window by: changing the size of the data sending window in real time according to the link status monitoring results; increasing the sending window to improve transmission efficiency when the link condition is good; and decreasing the sending window to reduce the sending rate when the link condition is poor. Dynamically adjusting the retransmission interval includes: adjusting the retransmission interval based on link status monitoring results; extending the retransmission interval when the link delay is large or the packet loss rate is high; and shortening the retransmission interval when the link condition is good. Dynamic priority scheduling strategies include: dynamically adjusting the transmission priority of different data based on link status and the importance and urgency of service data.

8. The reliable communication system based on publish-subscribe mode in a weak satellite-to-ground network environment according to claim 1, characterized in that, Under normal link conditions, the message exchange process, with the ground message queue terminal acting as the publisher and the on-board message queue terminal acting as the subscriber, proceeds in the following sequence: Ground applications generate messages based on business needs, bind them with unique topic identifiers, and publish business messages to ground message queue terminals through standardized interfaces. The ground message queue terminal registers the relationship between messages and their corresponding topics through the publish-subscribe module and persists the messages. When the link monitoring module detects that the satellite-to-ground link is in normal condition, it calls the enhanced QUIC protocol stack to perform multiplexing, low-latency handshake and congestion control optimization configuration. With end-to-end encryption enabled, the ground message queue terminal transmits encrypted service messages via the enhanced QUIC protocol over the satellite-to-ground link. The on-board message queue terminal receives and decrypts business messages and stores them persistently; after checking the subscription relationship, the on-board message queue terminal distributes the messages to the target on-board applications. After receiving the message, the on-board application processes the business and sends a receipt confirmation to the on-board message queue terminal. The on-board message queue terminal sends feedback through the satellite-to-ground link via the enhanced QUIC protocol, and the on-board message queue terminal sends the confirmation back to the ground message queue terminal. After receiving the acknowledgment message, the ground message queue terminal updates the persistent record based on the message offset and acknowledgment status, and notifies the ground application of the successful processing.

9. The reliable communication system based on publish-subscribe mode in a weak satellite-to-ground network environment according to claim 1, characterized in that, Under link anomaly conditions, the message interaction process, with the ground message queue terminal acting as the publisher and the on-board message queue terminal acting as the subscriber, proceeds in the following sequence: The ground application generates and binds business messages to the topic, and publishes them to the ground message queue terminal through the interface; The ground message queue terminal registers the topic and persistently stores the message and its current transmission offset; With end-to-end encryption enabled, the ground message queue terminal transmits encrypted service messages via the enhanced QUIC protocol over the satellite-to-ground link. When the ground message queue terminal detects a degraded or interrupted link quality through the link monitoring module, it suspends message transmission, records the abnormal link status, and persistently stores the messages. It also enables a breakpoint resumption mechanism to maintain the unacknowledged portion of the message and its offset information. When the link monitoring module detects that the link has been restored, it invokes the connection migration and multiplexing capabilities of the enhanced QUIC protocol to re-establish the transmission session without needing to re-handshake. The ground message queue terminal resumes message transmission based on the recorded offset and retransmits unacknowledged messages based on the fast recovery mechanism of the enhanced QUIC protocol. The onboard message queue terminal receives the resumed message data, merges it with the previously cached data to complete it, verifies message integrity, and persists the data. The onboard message queue terminal resends the message delayed due to the interruption to the onboard application. After the business processing is completed, it returns confirmation information and then sends the recovery confirmation and feedback back to the ground message queue terminal. After receiving the final confirmation, the ground message queue terminal updates its local persistent state, generates a notification that the recovery is complete, and feeds back the final business processing result to the ground application.

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