Inter-satellite laser communication link break retransmission method and device, communication equipment and readable storage medium

Abstract

The application relates to an intersatellite laser communication link breakage retransmission method and device, a communication device and a readable storage medium. By establishing a message interaction mechanism of data rollback and data request between a laser communication load and a routing load, decoupling processing of data preparation on the routing load side and link recovery on the laser communication load side is realized, the routing load does not need to monitor the physical link state in real time, and only needs to respond to the control message of the laser communication load to complete pointer rollback and retransmission triggering, thereby reducing the complexity of on-satellite software design. Through receiving a link state identifier, fast and bidirectional sensing of link interruption and recovery is realized, and after intersatellite laser link interruption, data can be automatically and quickly retransmitted from a certain position before the breakpoint. The data loss problem caused by instantaneous link breakage due to satellite micro-vibration and the like is effectively solved, the integrity and reliability of data transmission between relay satellites are significantly improved, and the quality of relay service is ensured.

Description

Technical Field

[0001] This application relates to the field of satellite communication technology, and in particular to a method, apparatus, communication equipment, computer-readable storage medium, and computer program product for retransmission of inter-satellite laser communication links that have been broken. Background Technology

[0002] With the development of space information network technology, laser communication has been widely used in inter-satellite and space-to-ground data transmission due to its high bandwidth and narrow beam characteristics. In the complex space environment, micro-vibrations of the satellite platform (such as the rotation of solar panels) or equipment malfunctions may cause momentary interruptions in laser communication links. These link interruptions result in the loss of data modulated onto the laser beam.

[0003] In traditional technologies, data retransmission mechanisms after link restoration, particularly for remote sensing satellite-to-ground transmission, typically involve retransmitting the entire file via command after link recovery. However, for laser communication between medium- and high-orbit relay satellites, the transmission mode is unique: relay satellites usually do not persistently store data for extended periods, and the transmitted data is often a multiplexed, mixed stream from multiple low-orbit user satellites. Using traditional file-level retransmission would not only result in poor timeliness but also lead to the repeated transmission of a large amount of irrelevant data, severely impacting relay service quality and link efficiency. Summary of the Invention

[0004] Therefore, it is necessary to provide a method, apparatus, communication equipment, computer-readable storage medium, and computer program product for retransmission of inter-satellite laser communication links in response to the above-mentioned technical problems.

[0005] In a first aspect, this application provides a method for retransmitting a disconnected link in inter-satellite laser communication. The method is applied to a first relay satellite acting as a data sender in inter-satellite laser communication. The first relay satellite includes a first routing payload for communication connections and a first laser communication payload. The method includes: The first routing payload multiplexes the received data from multiple user satellites into internal exchange frames and buffers them in the transmission queue; in response to the data request message sent by the first laser communication payload, it sends the internal exchange frames in the transmission queue to the first laser communication payload for transmission; If the first laser communication payload detects a communication link interruption with the second relay satellite, a data rollback message is sent to the first routing payload. The first routing load rolls back the sending pointer of the sending queue by M frames according to the data rollback message; M is a pre-set amount of retransmitted data, and M is a positive integer; If the first laser communication payload detects that the communication link with the second relay satellite has been restored, a data request message is sent to the first routing payload; The first routing payload retransmits the internal exchange frame in the transmission queue to the first laser communication payload, starting from the rollback transmission pointer position according to the data request message, so that the first laser communication payload can transmit to the second relay satellite; The first laser communication payload determines the interruption or recovery status of the communication link with the second relay satellite based on whether the laser signal of the second relay satellite is detected, or by parsing the receive link status identifier in the inter-satellite transmission frame sent by the second relay satellite.

[0006] In one embodiment, the minimum value of the retransmitted data amount M The following formula is used for calculation: Where R is the distance between the first relay satellite and the second relay satellite, in meters; C is the speed of light, in meters per second; t1 is the time interval between the data being sent from the first routing payload and the data being modulated and sent from the first laser communication payload, in seconds; t2 is the time interval between the first laser communication payload receiving the incoming beam and demodulating the receive link status identifier, in seconds; B is the information rate of communication between the first relay satellite and the second relay satellite, in bits per second; L is the frame length of the internal exchange frame, in bits; int[] represents the round-up function.

[0007] In one embodiment, the method further includes: after the first routing payload sends the Nth frame of the transmission queue to the first laser communication payload, it releases the storage space occupied by the NM-1th frame and each internal exchange frame before the NM-1th frame in the transmission queue, and retains the data from the NMth frame to the Nth frame in the transmission queue.

[0008] In one embodiment, the frame header of the inter-satellite transmission frame is provided with a receive link status identifier, which includes a normal status or an abnormal status.

[0009] In one embodiment, the method further includes: determining that a communication link interruption with the second relay satellite has been detected when the first laser communication payload does not detect the laser signal of the second relay satellite; or determining that a communication link interruption with the second relay satellite has been detected when the first laser communication payload parses the receive link status identifier in the inter-satellite transmission frame sent by the second relay satellite as an abnormal state.

[0010] In one embodiment, the method further includes: determining that the communication link with the second relay satellite has been restored when the first laser communication payload recaptures the laser signal of the second relay satellite and the baseband demodulation is normal, and the receiver link status identifier of the inter-satellite transmission frame sent by the second relay satellite is parsed as normal.

[0011] In one embodiment, the method further includes: re-establishing the communication link with the second relay satellite if the first laser communication payload detects an interruption in the communication link with the second relay satellite.

[0012] In one embodiment, the frame header of the internally exchanged frame carries a frame sequence number, which is used by the ground terminal station to identify and remove duplicate data frames generated during retransmission.

[0013] Secondly, this application also provides an inter-satellite laser communication link retransmission device. The device is applied to a first relay satellite acting as a data sender in inter-satellite laser communication. The first relay satellite includes a first routing payload for communication connection and a first laser communication payload. The device includes: The caching module is used to multiplex the received data from multiple user satellites into internal exchange frames and cache them in the transmission queue; in response to the data request message sent by the first laser communication payload, the internal exchange frames in the transmission queue are sent to the first laser communication payload for transmission. The rollback processing module is used to send a data rollback message to the first routing payload when the first laser communication payload detects an interruption in the communication link with the second relay satellite; the first routing payload rolls back the transmission pointer of the transmission queue by M frames according to the data rollback message; M is a pre-set amount of retransmitted data, and M is a positive integer; The request processing module is used to send a data request message to the first routing payload when the first laser communication payload detects that the communication link with the second relay satellite has been restored; the first routing payload retransmits the internal exchange frames in the transmission queue to the first laser communication payload according to the data request message, starting from the rollback transmission pointer position, so that the first laser communication payload can transmit to the second relay satellite. The first laser communication payload determines the interruption or recovery status of the communication link with the second relay satellite based on whether the laser signal of the second relay satellite is detected, or by parsing the receive link status identifier in the inter-satellite transmission frame sent by the second relay satellite.

[0014] Thirdly, this application also provides a communication device, including a memory and a processor, wherein the memory stores a computer program, and the processor executes the computer program to implement the steps of the method described in the first aspect.

[0015] Fourthly, this application also provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps of the method described in the first aspect.

[0016] Fifthly, this application also provides a computer program product, including a computer program that, when executed by a processor, implements the steps of the method described in the first aspect above.

[0017] The aforementioned inter-satellite laser communication link retransmission method, apparatus, communication equipment, computer-readable storage medium, and computer program product establish a message interaction mechanism for data rollback and data request between the laser communication payload and the routing payload. This decouples the data preparation on the routing payload side from the link restoration on the laser communication payload side. The routing payload does not need to monitor the physical link status in real time; it only needs to respond to the control messages from the laser communication payload to complete pointer rollback and retransmission triggering, reducing the complexity of onboard software design. By receiving link status identifiers, it achieves rapid, bidirectional perception of link interruption and recovery. Furthermore, after an inter-satellite laser link interruption, it can automatically and quickly resume data transmission from a position before the breakpoint. This effectively solves the data loss problem caused by instantaneous link interruptions due to satellite micro-vibrations, significantly improving the integrity and reliability of data transmission between relay satellites and ensuring the quality of relay services. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of this application or related technologies, the drawings used in the description of the embodiments of this application or related technologies will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a diagram illustrating the application environment of an inter-satellite laser communication link retransmission method in one embodiment. Figure 2 This is a schematic diagram illustrating the principle of an inter-satellite laser communication link retransmission method in one embodiment; Figure 3 This is a schematic diagram of the data format of an inter-satellite transmission frame in one embodiment; Figure 4 This is a flowchart illustrating an inter-satellite laser communication link retransmission method in one embodiment; Figure 5This is a flowchart illustrating the retransmission step in one embodiment. Figure 6 This is a flowchart illustrating the retransmission step in another embodiment; Figure 7 This is a structural block diagram of an inter-satellite laser communication link retransmission device in one embodiment; Figure 8 This is an internal structural diagram of a communication device in one embodiment. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0021] It should be noted that the terms "first," "second," etc., used in this application can be used to describe various elements, but these elements are not limited by these terms. These terms are only used to distinguish the first element from the second element. The terms "comprising" and "having," and any variations thereof, used in this application, are intended to cover non-exclusive inclusion. The term "multiple" used in this application refers to two or more. The term "and / or" used in this application refers to one of the embodiments, or any combination of multiple embodiments.

[0022] The inter-satellite laser communication link retransmission method provided in this application embodiment can be applied to, for example... Figure 1 The diagram illustrates a scenario where relay satellite A and relay satellite B relay data via an inter-satellite laser communication link. For example... Figure 1As shown, low-Earth orbit satellites 1, 2, and 3 can transmit data to relay satellite A via laser or microwave communication. Relay satellite A multiplexes the received data from multiple user satellites and forwards it to relay satellite B via an inter-satellite laser communication link. Relay satellite B then multiplexes the received data along with data from low-Earth orbit satellites 4 and 5 and transmits it to a ground terminal station via a satellite-to-ground microwave communication link. The ground terminal station separates the data and transmits it to each user center via a terrestrial network. Because the data transmitted from relay satellite A to relay satellite B is a mixed byte stream of data from different user satellites, if the inter-satellite laser communication link is interrupted, the data from multiple user satellites will be simultaneously corrupted, severely affecting the relay service quality. Therefore, this application sets a receive link status identifier field in the inter-satellite transmission frame between the two relay satellites. The laser communication terminals of the two relay satellites use the receive link status identifier field to indicate to each other whether they can continue to receive data correctly. If the other party cannot correctly receive the data sent by itself, it indicates that the communication link is interrupted. After the receiving link status indicator returns to normal, indicating that the link is operational again, a fixed length of data will be retransmitted to ensure that data sent before the link interruption but which the other party may not have received is not lost. The retransmitted data may contain duplicates (i.e., duplicate frames). The removal of duplicate frames is performed separately at the ground terminal station to ensure that no data is lost. This significantly improves the integrity and reliability of data transmission between relay satellites and guarantees the quality of relay services.

[0023] In one exemplary embodiment, such as Figure 2 As shown, each relay satellite is equipped with a routing payload and a laser communication payload for inter-satellite laser communication. The routing payload and the laser communication payload exchange messages and data through an internal interface. The routing payload is responsible for multiplexing user satellite data, encapsulating user satellite data frames of different formats and lengths into fixed-format, fixed-length internal exchange frames, and sending them to the laser communication payload according to the set forwarding path. Simultaneously, the routing payload is also responsible for receiving data received by the laser communication payload, synchronizing the frames, restoring them into internal exchange frames, and then forwarding them according to the set path.

[0024] The laser communication payload is responsible for receiving internal exchange frame data from the routing payload, truncating it into fixed-length byte streams and encapsulating it into inter-satellite transmission frames, modulating them onto a laser beam and transmitting them to the relay satellite at the other end; at the same time, it receives inter-satellite transmission frames from the relay satellite at the other end, decapsulates them, and forms byte streams to transmit to the routing payload; in addition, the laser communication payload is also responsible for monitoring the link status, sending a data rollback message to the routing payload when it does not receive inter-satellite transmission frame data from the other end or when it learns that the link is interrupted by receiving the link status identifier, and sending a data request message when the link is restored to normal to achieve data retransmission.

[0025] In one exemplary embodiment, the data format of the inter-satellite transmission frame is as follows: Figure 3 As shown, the system includes a frame synchronization word, a frame header, a data field, and a check bit. The frame synchronization word is used to define the frame boundaries of multiple inter-satellite transmission frames. The frame header expresses the encapsulation information of the frame data, such as the length of the valid data in the data field and the receive link status identifier. The data field is filled with the valid data to be transmitted. When there is no valid data or the valid data length is insufficient to cover the entire data field, the data field is filled with the sequence "010101..." as invalid data. Inter-satellite transmission frames without valid data are called idle data frames. The check bit can be generated by encoding the data in the frame header and data field using a forward error correction coding algorithm (such as LDPC or RS coding). It is used by the demodulator to detect and correct errors when a small number of errors occur during transmission.

[0026] It should be noted that the receive link status flag field in the frame header of the inter-satellite transmission frame is 1 bit long. When the relay satellite's laser communication payload antenna is in a stable tracking state and the baseband demodulation is correct, this flag is set to "1", indicating that the local receive link is in a normal state and can continue to receive data. When the relay satellite's laser communication payload antenna loses lock or the baseband demodulation is abnormal, this flag is set to "0", indicating that the local receive link is in an abnormal state and cannot receive data normally. When the laser communication payload transmits each inter-satellite transmission frame (whether it is a valid data frame or an idle data frame), it sets this receive link status flag according to the tracking status of its own antenna and the baseband demodulation status, thereby expressing its own operating status to the laser communication payload at the other end in real time.

[0027] This embodiment achieves real-time bidirectional notification of link status by embedding a 1-bit receive link status identifier in the frame header of the inter-satellite transmission frame. This allows the sender to not only determine the link status by whether it receives an optical signal, but also to know whether the receiver has failed to receive the signal due to baseband anomalies or other reasons. This enables more accurate and comprehensive link failure detection and provides a reliable basis for the accurate triggering of the retransmission mechanism.

[0028] In one exemplary embodiment, such as Figure 4 As shown, a method for retransmission of inter-satellite laser communication links is provided, which is applied to the first relay satellite (e.g., the data sender) in inter-satellite laser communication. Figure 1 Taking relay satellite A as an example, in this embodiment, for ease of understanding, the routing payload of the first relay satellite is defined as the first routing payload, and the laser communication payload of the first relay satellite is defined as the first laser communication payload. The method may specifically include the following steps: Step 402: The first routing payload performs data caching and normal data transmission.

[0029] Specifically, the first routing payload receives data from multiple user satellites and multiplexes this data to form internally exchanged frames with a uniform format. These internally exchanged frames are buffered in a first-in-first-out (FIFO) transmission queue.

[0030] Under normal communication link conditions, the first laser communication payload sends a data request message to the first routing payload. In response to this message, the first routing payload retrieves an internal exchange frame from the current position of the transmission pointer in the transmission queue and sends it to the first laser communication payload. The first laser communication payload encapsulates the received internal exchange frame data stream into an inter-satellite transmission frame, sets the receiving link status flag in the frame header according to the receiving status of its local laser communication link, modulates the inter-satellite transmission frame onto a laser beam, and sends it to the second relay satellite (e.g., a second relay satellite). Figure 1 (Relay satellite B in the middle).

[0031] Step 404: If the first laser communication payload detects an interruption in the communication link with the second relay satellite, a data rollback message is sent to the first routing payload.

[0032] In this embodiment, the first laser communication payload continuously monitors the communication link status with the second relay satellite. For example, the first laser communication payload continuously receives inter-satellite transmission frames sent by the second relay satellite and parses the receive link status identifier within them. When the first laser communication payload does not receive the laser signal from the second relay satellite (e.g., due to beam deviation caused by satellite vibration), or parses the receive link status identifier in the inter-satellite transmission frame sent by the second relay satellite as "0" (e.g., abnormal baseband demodulation at the peer end), it determines that the communication link with the second relay satellite is interrupted. At this time, the first laser communication payload sends a data rollback message to the first routing payload, enabling the first routing payload to prepare for retransmission based on the data rollback message. Simultaneously, the first laser communication payload stops sending valid data and instead sends idle data frames, setting the receive link status identifier in the idle data frame header to "0" (no laser signal received or abnormal local baseband demodulation) or "1" (detection of abnormal baseband demodulation at the peer end but normal local baseband demodulation), and initiates the corresponding link recovery process (such as scan recapture or baseband self-test).

[0033] Step 406: The first routing payload rolls back the sending pointer of the sending queue by M frames according to the data rollback message.

[0034] In this embodiment, after receiving the data rollback message sent by the first laser communication payload, the first routing payload rolls back the transmission pointer of the transmission queue from the current position (e.g., frame N) by M frames, thereby pointing to frame NM. Here, M is a pre-defined positive integer representing the amount of retransmitted data that needs to be retransmitted; its specific calculation method will be detailed in subsequent embodiments.

[0035] Step 408: If the first laser communication payload detects that the communication link with the second relay satellite has been restored, a data request message is sent to the first routing payload.

[0036] In this embodiment, when the first laser communication payload re-captures the laser signal from the second relay satellite and the baseband demodulation is normal, and the receive link status identifier in the inter-satellite transmission frame sent by the second relay satellite is restored to "1" (i.e., normal state), it is determined that the communication link with the second relay satellite has been restored. At this time, the first laser communication payload sends a data request message to the first routing payload, indicating that it can continue to transmit data to the second relay satellite.

[0037] Step 410: The first routing payload retransmits the internal exchange frames in the transmission queue to the first laser communication payload, starting from the position of the transmission pointer after the rollback, according to the data request message.

[0038] After receiving a new data request message, the first routing payload, starting from the rollback transmission pointer position (i.e., frame NM), sequentially retransmits the internal exchange frames to the first laser communication payload. The first laser communication payload encapsulates these frames and sends them to the second relay satellite, thus completing the data retransmission during the link loss period.

[0039] In the aforementioned inter-satellite laser communication link retransmission method, a message interaction mechanism for data rollback and data request is established between the laser communication payload and the routing payload. This decouples the data preparation on the routing payload side from the link restoration on the laser communication payload side. The routing payload does not need to monitor the physical link status in real time; it only needs to respond to the control messages from the laser communication payload to complete pointer rollback and retransmission triggering, reducing the complexity of onboard software design. By receiving link status identifiers, rapid, bidirectional perception of link interruption and recovery is achieved. Furthermore, after an inter-satellite laser link interruption, data can be automatically and quickly retransmitted from a position before the breakpoint. This effectively solves the data loss problem caused by instantaneous link interruptions due to satellite micro-vibrations, significantly improving the integrity and reliability of data transmission between relay satellites and ensuring the quality of relay services.

[0040] In an exemplary embodiment, to support data retransmission, the first routing payload internally maintains a first-in-first-out (FIFO) transmission queue (let's say queue 1) to buffer internal exchange frames to be sent to the first laser communication payload. After reading an internal exchange frame from transmission queue 1 and sending it to the first laser communication payload, the first routing payload does not immediately release the storage space occupied by that frame data. Instead, it retains a waiting period to confirm that the frame data no longer needs to be retransmitted before releasing it.

[0041] Specifically, after the first routing payload sends the Nth frame of the internal exchange in transmission queue 1 to the first laser communication payload, it only releases the storage space occupied by the NM-1th frame and all internal exchange frames before the NM-1th frame in transmission queue 1. The data for the M+1 frames from the NMth frame to the Nth frame remains in transmission queue 1. Thus, when the first routing payload receives a data rollback message, the transmission pointer can successfully roll back to the NMth frame because this frame and subsequent data are still fully buffered and can be immediately used for retransmission.

[0042] This embodiment provides a data foundation for retransmission after a link break by retaining the most recently transmitted M+1 frame data in the transmission queue. This delayed release storage management strategy achieves effective caching of retransmitted data under the condition of limited on-board storage resources. It avoids the problem of being unable to rollback due to insufficient caching, and also prevents the waste of storage resources caused by indiscriminate long-term caching, thus achieving a balance between storage efficiency and data integrity.

[0043] In one exemplary embodiment, to ensure that data that may be lost during a link interruption can be retransmitted, the value of the retransmitted data volume M needs to be large enough to cover all data sent within the entire time window from when the data leaves the routing payload to when the sending laser communication payload senses the link interruption.

[0044] For example, the minimum value of the retransmitted data volume M It can be calculated according to the following formula (1): (1) Where R is the distance between the first relay satellite and the second relay satellite, in meters (m); C is the speed of light, in meters per second (m / s); t1 is the time interval between the transmission of data from the first routing payload and the modulation and transmission of data from the first laser communication payload, in seconds (s); t2 is the time interval between the first laser communication payload receiving the incoming beam and demodulating the receive link status identifier, in seconds (s); B is the information rate of communication between the first relay satellite and the second relay satellite, in bits per second (bps); L is the frame length of the internal exchange frame, in bits (bit); int[] represents the round-up function.

[0045] Furthermore, the physical analysis of the above formula (1) is as follows: 2R / C represents the round-trip propagation delay of the signal from the first relay satellite to the second relay satellite and back. After the link interruption event occurs, the first relay satellite needs to wait at least this long before it can sense the interruption through the feedback (or signal loss) from the second relay satellite. t1 represents the processing and queuing delay within the routing payload; t2 represents the reception and processing delay of the laser communication payload. The sum of these three terms (2R / C+t1+t2) constitutes the total delay in the worst-case scenario from when the data leaves the routing payload to when the sender confirms the link interruption. (2R / C+t1+t2)*B represents the maximum amount of data that can theoretically be transmitted (in bits) within the above total delay. (2R / C+t1+t2)*B / L represents the result of converting the maximum amount of data into the number of frames.

[0046] In practical applications, to ensure redundancy and reliability, the M value preset via remote control commands is usually greater than the calculated minimum value. For example, in one scenario, if the distance R between two relay satellites is 32,000 km, the communication code rate is 5 Gbps, and the inter-satellite transmission frame length is 1024 bytes, with a data field length of 880 bytes, then the information rate B is 4,296,875,000 bps; assuming t1 and t2 are both 10 ms; and the frame length L of the internal exchange frame is 1056 bytes (i.e., 8448 bits), then calculate the minimum value of the retransmitted data volume M. The total length is 118,754 frames (approximately 120 Mbytes). To ensure redundancy and reliability, the M value can be pre-specified to 200,000 via remote control commands. That is, during normal communication, when the transmitting end's routing load transmits the Nth frame of data from the queue to the laser communication load, it only releases the storage space occupied by the N-200,001st frame. When the communication link is interrupted, after receiving the data rollback message, the routing load jumps the transmission pointer from the Nth frame to the N-200,000th frame. After the link is restored, it resumes transmitting data to the laser communication load starting from the N-200,000th frame.

[0047] This embodiment provides a scientific and rigorous calculation method to determine the minimum value of the retransmitted data volume M. This method comprehensively considers key factors such as inter-satellite distance, signal propagation delay, device processing delay, and communication rate, ensuring that all data potentially lost during link interruption can be retransmitted and covered even in extreme cases of maximum propagation delay and maximum processing delay. This fundamentally avoids permanent data loss due to insufficient retransmitted data volume, and the reliability of the solution is guaranteed by rounding up and reserving redundancy.

[0048] In an exemplary embodiment, when the first laser communication payload detects a communication link interruption and sends a data rollback message to the first routing payload, it can simultaneously stop sending valid data frames and instead send idle data frames. The data field of the idle data frame is filled with the sequence "010101...", and the receive link status identifier in its frame header is set according to the actual receive status of the local end: if the local antenna is out of lock or the baseband demodulation is abnormal, it is set to "0" (i.e., abnormal state); if the local end receives normally but detects an abnormality at the other end, the local identifier is still set according to the local end's status.

[0049] During link restoration, the first laser communication payload continuously sends idle data frames, enabling the other end to continuously receive optical signals and parse the receive link status identifier, thereby confirming the link status at this end. Once both parties set the receive link status identifier to "1" and send idle data frames to each other, they can confirm that the link is bidirectionally accessible, i.e., the communication link has been restored. Subsequently, they stop sending idle data frames and resume sending valid data frames.

[0050] This embodiment ensures the continuous transmission of link status information by sending idle data frames carrying the received link status identifier during link interruption and recovery, rather than remaining silent. This allows both communicating parties to monitor the other end's status in real time through idle data frames even during the link recovery period when no valid data is being sent, avoiding a status information vacuum caused by the cessation of frame transmission. This shortens the retransmission start delay after link recovery and improves the timeliness of relay communication.

[0051] In one exemplary embodiment, since the retransmission mechanism involves rolling back M frames and then retransmitting, the retransmitted data stream may contain data that was successfully transmitted and received by the second relay satellite before the link was lost, resulting in duplicate data frames (repeated frames). Therefore, to address this issue, in this example, the frame header of the generated internally exchanged frame carries a frame sequence number. This frame sequence number can be assigned sequentially during data multiplexing and is globally unique and continuous.

[0052] Once the retransmitted data is finally relayed to the ground terminal station via the second relay satellite, the ground terminal station can sort and check all received data based on the frame sequence number in the internal exchange frame, thereby identifying and removing duplicate frames to recover the complete and non-duplicate original data stream.

[0053] This embodiment shifts the complexity of deduplication from the satellite to the ground by setting frame sequence numbers in the internal exchange frames and removing duplicate frames at the ground terminal station. The satellite routing payload and laser communication payload no longer need to perform complex duplicate frame detection and filtering during retransmission, simplifying the satellite processing logic and reducing the consumption of satellite computing and storage resources. By utilizing the powerful computing capabilities of the ground terminal station, deduplication can be completed efficiently and accurately. Furthermore, the introduction of frame sequence numbers provides a basis for data integrity verification, ensuring that the data finally delivered to the user center is complete and without duplication.

[0054] To further illustrate the principles of this application, the following section details the inter-satellite laser communication link interruption and retransmission process based on different causes of inter-satellite laser communication link interruption. Specifically, the causes of inter-satellite laser communication link interruption mainly include two types: The first is laser beam deviation, meaning the relay satellite's laser communication payload does not receive the optical signal. In this scenario, the laser communication payloads of both communicating parties may lose signals almost simultaneously, indicating that both receiving links are abnormal. The second is that the laser communication payload receives the optical signal and tracks normally, but the baseband malfunctions, failing to correctly demodulate the modulated data on the beam. In this scenario, usually only one party's receiving link is abnormal. For example, the following explanation uses relay satellite A as the data sender (first relay satellite) and relay satellite B as the data receiver (second relay satellite).

[0055] In one scenario, let's illustrate the above-mentioned retransmission process by taking a bidirectional link interruption caused by laser beam deviation as an example. Because the laser beam divergence angle is extremely narrow, micro-vibrations on the satellite platform due to factors such as solar panel rotation and attitude adjustments can cause the laser beam to deviate from the receiving target surface. Furthermore, since the transmitting and receiving optical paths within the laser communication payload are usually parallel and coincident, if one side fails to receive a light signal, it can be inferred that the other side has also failed to receive a light signal, i.e., a bidirectional communication link interruption. For example... Figure 5 As shown, the retransmission process in this scenario includes the following steps: Step 502, normal data transmission phase.

[0056] When the communication link between the first relay satellite and the second relay satellite is normal, the system is in the normal data transmission phase. That is, the first laser communication payload of the first relay satellite is transmitting valid data normally, the first routing payload transmission pointer is pointing to the Nth frame, and at the same time, it is receiving the laser signal from the second relay satellite and demodulating the modulated data on it.

[0057] Step 504, Communication Link Interruption Stage.

[0058] In this embodiment, it is assumed that the laser beam deviates due to micro-vibrations caused by the rotation of the solar panels of either the first or second relay satellite. If the tracking camera of the first laser communication payload of the first relay satellite fails to detect the laser signal emitted by the second relay satellite, it is determined that the laser communication payload of the second relay satellite also cannot receive the light signal emitted by itself, thus confirming a communication link interruption. At this time, the data transmitted within approximately δ time (δ≈2R / C) may not have been received normally by the other end due to the beam deviation and needs to be retransmitted. The first laser communication payload of the first relay satellite then pushes a data rollback message to the first routing payload, simultaneously stops sending valid data, starts sending idle data frames, sets the receive link status flag in the idle data frame header to "0", and initiates a scan recapture process to attempt to recapture the light signal.

[0059] Step 506: Send pointer rollback.

[0060] After receiving the data rollback message, the first routing payload of the first relay satellite rolls back the transmission pointer of the transmission queue from the current Nth frame to the NMth frame.

[0061] Step 508, Chain Reconstruction Phase.

[0062] After the laser communication payloads of both the first and second relay satellites scan and recapture the optical signal and the baseband demodulation is normal, they set the receive link status flag in the frame header of the idle data frame being transmitted to "1" and send it to the other party.

[0063] Step 510, Link Recovery Phase.

[0064] After receiving an idle data frame sent by the second relay satellite, the first laser communication payload of the first relay satellite found that the receive link status identifier was "1". It determined that the laser communication payload of the second relay satellite could receive its own data normally, so it stopped sending idle data frames, started sending valid data, and pushed a data request message to the first routing payload.

[0065] Step 512, data retransmission stage.

[0066] After receiving the data request message, the first routing payload of the first relay satellite transmits the data in the transmission queue starting from frame NM to the first laser communication payload. The first laser communication payload then encapsulates the data and sends it to the second relay satellite, thereby completing the retransmission of data lost during the link outage.

[0067] This embodiment addresses beam deviation, a typical inter-satellite laser communication failure mode. By simultaneously sensing optical signal loss in both directions, it achieves near-synchronous link failure detection between the two parties. Through pre-calculation and rollback of M frames, it ensures that all data potentially lost during beam deviation (including the optical propagation delay) is retransmitted and overwritten. Since both parties simultaneously initiate scanning and reacquisition, and mutually confirm their status via idle data frames after successful reacquisition, it avoids data loss due to unilateral blind resumption of transmission, significantly improving data transmission integrity and retransmission efficiency in this common failure mode.

[0068] In another scenario, let's take the cause of link interruption as an example: the laser communication payload receives an optical signal and the antenna tracking is normal, but the baseband demodulation is abnormal, resulting in only one side being unable to receive data normally. This example illustrates the above-mentioned link retransmission process. Figure 6 As shown, the retransmission process in this scenario includes the following steps: Step 602, normal data transmission phase.

[0069] When the communication link between the first relay satellite and the second relay satellite is normal, the system is in the normal data transmission phase. That is, the first laser communication payload of the first relay satellite is transmitting valid data normally, the first routing payload transmission pointer is pointing to the Nth frame, and at the same time, it is receiving the laser signal from the second relay satellite and demodulating the modulated data on it.

[0070] Step 604, Communication Link Interruption Stage.

[0071] In this embodiment, assuming an anomaly occurs in the baseband demodulation of the laser communication payload of the second relay satellite (e.g., phase-locked loop loss, decoder failure, etc.), its receive link status flag is automatically set to "0" and sent to the first relay satellite via an inter-satellite transmission frame (which can be a valid data frame or an idle data frame). Simultaneously, the laser communication payload of the second relay satellite initiates a self-test or restart process for its baseband receive channel.

[0072] After receiving the inter-satellite transmission frame from the second relay satellite, the laser communication payload of the first relay satellite found that the receive link status identifier was "0", indicating that the laser communication payload of the second relay satellite could not receive data normally. At this time, the first relay satellite determined that the data sent within approximately δ time (δ≈2R / C) might have failed to be received normally due to demodulation anomalies at the other end and needed to be retransmitted. Therefore, the first laser communication payload of the first relay satellite pushed a data rollback message to the first routing payload, and simultaneously stopped sending valid data and began sending idle data frames.

[0073] Step 606: Send pointer rollback.

[0074] After receiving the data rollback message, the first routing payload of the first relay satellite rolls back the transmission pointer of the transmission queue from the current Nth frame to the NMth frame.

[0075] Step 608, Link Recovery Phase.

[0076] After self-testing or restarting, the baseband receiving channel of the laser communication payload of the second relay satellite returned to normal, its receiving link status flag was set to "1", and it was sent to the first relay satellite through inter-satellite transmission frames.

[0077] After receiving the inter-satellite transmission frame, the first laser communication payload of the first relay satellite found that the receiving link status identifier was "1". Based on this, it was determined that the baseband receiving channel of the laser communication payload of the second relay satellite had returned to normal. At this time, it stopped sending idle data, began to prepare to send valid data, and pushed a data request message to the first relay payload.

[0078] Step 610, data retransmission stage.

[0079] After receiving the data request message, the first routing payload of the first relay satellite transmits the data in the transmission queue starting from frame NM to the first laser communication payload. The first laser communication payload then encapsulates the data and sends it to the second relay satellite, thereby completing the retransmission of data lost during the link outage.

[0080] This embodiment addresses a fault mode that only affects single-end reception capability, such as baseband demodulation anomalies. By transmitting the receiving link status identifier across satellites, the sender (first relay satellite) can promptly learn of the receiver's (second relay satellite) internal baseband fault status without waiting for timeouts or relying on ground intervention. Upon learning of the anomaly, the sender immediately initiates rollback and idle data frame transmission. Once baseband recovery is achieved, the receiver notifies the sender via the status identifier, ensuring precise coordination between fault recovery and retransmission initiation. This design prevents the sender from unknowingly transmitting large amounts of incorrectly demodulated data, reducing invalid data transmission and onboard energy consumption, while ensuring data continuity after baseband recovery.

[0081] It should be understood that although the steps in the flowcharts of the embodiments described above are shown sequentially according to the arrows, these steps are not necessarily executed in the order indicated by the arrows. Unless explicitly stated herein, there is no strict order restriction on the execution of these steps, and they can be executed in other orders. Moreover, at least some steps in the flowcharts of the embodiments described above may include multiple steps or multiple stages. These steps or stages are not necessarily completed at the same time, but can be executed at different times. The execution order of these steps or stages is not necessarily sequential, but can be performed alternately or in turn with other steps or at least some of the steps or stages in other steps. It is understood that the steps in different embodiments can be freely combined as needed, and all non-contradictory solutions formed by such combinations are within the scope of protection of this application.

[0082] Based on the same inventive concept, this application also provides an apparatus for implementing the inter-satellite laser communication link retransmission method described above. The solution provided by this apparatus is similar to the implementation described in the above method; therefore, specific limitations in one or more apparatus embodiments provided below can be found in the limitations of the inter-satellite laser communication link retransmission method described above, and will not be repeated here.

[0083] In one exemplary embodiment, such as Figure 7 As shown, an inter-satellite laser communication link retransmission device is provided. The device is applied to a first relay satellite acting as a data sender in inter-satellite laser communication. The first relay satellite includes a first routing payload for communication connection and a first laser communication payload. The device includes: a buffer module 702, a rollback processing module 704, and a request processing module 706, wherein: The caching module 702 is used to multiplex the received data from multiple user satellites into internal exchange frames and cache them in the transmission queue; in response to the data request message sent by the first laser communication payload, the internal exchange frames in the transmission queue are sent to the first laser communication payload for transmission. The rollback processing module 704 is used to send a data rollback message to the first routing payload when the first laser communication payload detects an interruption in the communication link with the second relay satellite; the first routing payload rolls back the transmission pointer of the transmission queue by M frames according to the data rollback message; M is a pre-set amount of retransmitted data, and M is a positive integer; The request processing module 706 is used to send a data request message to the first routing payload when the first laser communication payload detects that the communication link with the second relay satellite has been restored; the first routing payload retransmits the internal exchange frame in the transmission queue to the first laser communication payload from the rollback transmission pointer position according to the data request message, so that the first laser communication payload can transmit to the second relay satellite. The first laser communication payload determines the interruption or recovery status of the communication link with the second relay satellite based on whether the laser signal of the second relay satellite is detected, or by parsing the receive link status identifier in the inter-satellite transmission frame sent by the second relay satellite.

[0084] In one exemplary embodiment, the minimum value of the retransmitted data amount M The following formula is used for calculation: Where R is the distance between the first relay satellite and the second relay satellite, in meters; C is the speed of light, in meters per second; t1 is the time interval between the data being sent from the first routing payload and the data being modulated and sent from the first laser communication payload, in seconds; t2 is the time interval between the first laser communication payload receiving the incoming beam and demodulating the receive link status identifier, in seconds; B is the information rate of communication between the first relay satellite and the second relay satellite, in bits per second; L is the frame length of the internal exchange frame, in bits; int[] represents the round-up function.

[0085] In an exemplary embodiment, after the first routing payload sends the Nth frame of the transmission queue to the first laser communication payload, it releases the storage space occupied by the NM-1th frame and all the internal exchange frames before the NM-1th frame in the transmission queue, and retains the data from the NMth frame to the Nth frame in the transmission queue.

[0086] In an exemplary embodiment, the frame header of the inter-satellite transmission frame is provided with a receive link status identifier, which includes a normal status or an abnormal status.

[0087] In an exemplary embodiment, if the first laser communication payload does not detect the laser signal from the second relay satellite, it is determined that a communication link interruption with the second relay satellite has been detected; or, if the first laser communication payload parses the receive link status identifier in the inter-satellite transmission frame sent by the second relay satellite as an abnormal state, it is determined that a communication link interruption with the second relay satellite has been detected.

[0088] In an exemplary embodiment, if the first laser communication payload recaptures the laser signal of the second relay satellite and the baseband demodulation is normal, and the receive link status identifier of the inter-satellite transmission frame sent by the second relay satellite is parsed as normal, it is determined that the communication link with the second relay satellite has been restored.

[0089] In one exemplary embodiment, the frame header of the internally exchanged frame carries a frame sequence number, which is used by the ground terminal station to identify and remove duplicate data frames generated during retransmission.

[0090] Each module in the aforementioned inter-satellite laser communication link retransmission device can be implemented entirely or partially through software, hardware, or a combination thereof. These modules can be embedded in or independent of the processor in a computer device, or stored in the memory of a computer device as software, so that the processor can call and execute the corresponding operations of each module.

[0091] In one exemplary embodiment, a communication device is provided, the internal structure of which can be shown in the following diagram. Figure 8 As shown, the communication device includes a processor, memory, input / output interface, communication interface, display unit, and input device. The processor, memory, and input / output interface are connected via a system bus, and the communication interface, display unit, and input device are also connected to the system bus via the input / output interface. The processor provides computing and control capabilities. The memory includes a non-volatile storage medium and internal memory. The non-volatile storage medium stores the operating system and computer programs. The internal memory provides an environment for the operation of the operating system and computer programs in the non-volatile storage medium. The input / output interface is used for exchanging information between the processor and external devices. The communication interface is used for wired or wireless communication with external terminals; wireless communication can be achieved through Wi-Fi, mobile cellular networks, Near Field Communication (NFC), or other technologies. When executed by the processor, the computer program implements an inter-satellite laser communication link retransmission method. The display unit is used to form a visually visible image and can be a display screen, projection device, or virtual reality imaging device. The display screen can be an LCD screen or an e-ink screen. The input device of the communication device can be a touch layer covering the display screen, or buttons, trackballs, or touchpads set on the casing of the communication device, or external keyboards, touchpads, or mice, etc.

[0092] Those skilled in the art will understand that Figure 8The structure shown is merely a block diagram of a portion of the structure related to the present application and does not constitute a limitation on the communication device to which the present application is applied. Specific communication devices may include more or fewer components than those shown in the figure, or combine certain components, or have different component arrangements.

[0093] In one exemplary embodiment, a communication device is provided, including a memory and a processor, wherein the memory stores a computer program, and the processor executes the computer program to implement the steps in the above-described method embodiments.

[0094] In one embodiment, a computer-readable storage medium is provided having a computer program stored thereon, which, when executed by a processor, implements the steps in the above method embodiments.

[0095] In one embodiment, a computer program product is provided, including a computer program that, when executed by a processor, implements the steps in the above method embodiments.

[0096] It should be noted that the user information (including but not limited to user device information, user personal information, etc.) and data (including but not limited to data used for analysis, data stored, data displayed, etc.) involved in this application are all information and data authorized by the user or fully authorized by all parties, and the collection, use and processing of the relevant data must comply with relevant regulations.

[0097] Those skilled in the art will understand that all or part of the processes in the methods of the above embodiments can be implemented by a computer program instructing related hardware. The computer program can be stored in a non-volatile computer-readable storage medium, and when executed, it can include the processes of the embodiments of the above methods. Any references to memory, databases, or other media used in the embodiments provided in this application can include at least one of non-volatile memory and volatile memory. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory, optical memory, high-density embedded non-volatile memory, resistive random access memory (ReRAM), magnetic random access memory (MRAM), ferroelectric random access memory (FRAM), phase change memory (PCM), graphene memory, etc. Volatile memory can include random access memory (RAM) or external cache memory, etc. By way of illustration and not limitation, RAM can take many forms, such as Static Random Access Memory (SRAM) or Dynamic Random Access Memory (DRAM). The databases involved in the embodiments provided in this application may include at least one type of relational database and non-relational database. Non-relational databases may include, but are not limited to, blockchain-based distributed databases. The processors involved in the embodiments provided in this application may be general-purpose processors, central processing units, graphics processing units, digital signal processors, programmable logic devices, quantum computing-based data processing logic devices, artificial intelligence (AI) processors, etc., and are not limited to these.

[0098] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this application.

[0099] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of this patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this application should be determined by the appended claims.

Claims

1. A method for retransmitting interrupted links in inter-satellite laser communication, characterized in that, The method is applied to a first relay satellite acting as a data sender in inter-satellite laser communication. The first relay satellite includes a first routing payload for communication connections and a first laser communication payload. The method includes: The first routing payload multiplexes the received data from multiple user satellites into internal exchange frames and buffers them in the transmission queue; in response to the data request message sent by the first laser communication payload, it sends the internal exchange frames in the transmission queue to the first laser communication payload for transmission; If the first laser communication payload detects a communication link interruption with the second relay satellite, a data rollback message is sent to the first routing payload. The first routing load rolls back the sending pointer of the sending queue by M frames according to the data rollback message; M is a pre-set amount of retransmitted data, and M is a positive integer; If the first laser communication payload detects that the communication link with the second relay satellite has been restored, a data request message is sent to the first routing payload; The first routing payload retransmits the internal exchange frame in the transmission queue to the first laser communication payload, starting from the rollback transmission pointer position according to the data request message, so that the first laser communication payload can transmit to the second relay satellite; The first laser communication payload determines the interruption or recovery status of the communication link with the second relay satellite based on whether the laser signal of the second relay satellite is detected, or by parsing the receive link status identifier in the inter-satellite transmission frame sent by the second relay satellite.

2. The method according to claim 1, characterized in that, The minimum value of the retransmitted data amount M The following formula is used for calculation: Where R is the distance between the first relay satellite and the second relay satellite, in meters; C is the speed of light, in meters per second; t1 is the time interval between the data being sent from the first routing payload and the data being modulated and sent from the first laser communication payload, in seconds; t2 is the time interval between the first laser communication payload receiving the incoming beam and demodulating the receive link status identifier, in seconds; B is the information rate of communication between the first relay satellite and the second relay satellite, in bits per second; L is the frame length of the internal exchange frame, in bits; int[] represents the round-up function.

3. The method according to claim 1, characterized in that, The method further includes: After the first routing payload sends the Nth frame of the transmission queue to the first laser communication payload, it releases the storage space occupied by the NM-1 frame and the previous internal exchange frames in the transmission queue, and retains the data from the NM frame to the Nth frame in the transmission queue.

4. The method according to claim 1, characterized in that, The frame header of the inter-satellite transmission frame contains a receive link status identifier, which includes a normal status or an abnormal status.

5. The method according to claim 4, characterized in that, The method further includes: If the first laser communication payload does not detect the laser signal from the second relay satellite, it is determined that a communication link interruption with the second relay satellite has been detected; or, If the first laser communication payload parses the receive link status identifier in the inter-satellite transmission frame sent by the second relay satellite as an abnormal state, it is determined that a communication link interruption with the second relay satellite has been detected.

6. The method according to claim 4, characterized in that, The method further includes: If the first laser communication payload recaptures the laser signal of the second relay satellite and the baseband demodulation is normal, and the receiver link status identifier of the inter-satellite transmission frame sent by the second relay satellite is parsed as normal, it is determined that the communication link with the second relay satellite has been restored.

7. The method according to any one of claims 1 to 6, characterized in that, The frame header of the internal exchange frame carries a frame sequence number, which is used by the ground terminal station to identify and remove duplicate data frames generated during the retransmission process.

8. An inter-satellite laser communication link retransmission device, characterized in that, The device is used in inter-satellite laser communication as a first relay satellite acting as a data transmitter. The first relay satellite includes a first routing payload for communication connection and a first laser communication payload. The device includes: The caching module is used to multiplex the received data from multiple user satellites into internal exchange frames and cache them in the transmission queue; in response to the data request message sent by the first laser communication payload, the internal exchange frames in the transmission queue are sent to the first laser communication payload for transmission. The rollback processing module is used to send a data rollback message to the first routing payload when the first laser communication payload detects an interruption in the communication link with the second relay satellite; the first routing payload rolls back the transmission pointer of the transmission queue by M frames according to the data rollback message; M is a pre-set amount of retransmitted data, and M is a positive integer; The request processing module is used to send a data request message to the first routing payload when the first laser communication payload detects that the communication link with the second relay satellite has been restored; the first routing payload retransmits the internal exchange frames in the transmission queue to the first laser communication payload according to the data request message, starting from the rollback transmission pointer position, so that the first laser communication payload can transmit to the second relay satellite. The first laser communication payload determines the interruption or recovery status of the communication link with the second relay satellite based on whether the laser signal of the second relay satellite is detected, or by parsing the receive link status identifier in the inter-satellite transmission frame sent by the second relay satellite.

9. A communication device, comprising a memory and a processor, wherein the memory stores a computer program, characterized in that, When the processor executes the computer program, it implements the steps of the method according to any one of claims 1 to 7.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by a processor, it implements the steps of the method according to any one of claims 1 to 7.

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