Time synchronization method for integrated inter-satellite and intra-satellite communications based on TSN

Abstract

The present invention provides a time synchronization method for integrated inter-satellite and intra-satellite communications based on TSN, which can implement a time-sensitive network protocol within the inter-satellite satellite to achieve time synchronization of inter-satellite and intra-satellite data communications. The present invention studies the corresponding scheduling mechanism algorithms respectively according to the business requirements of intra-satellite and inter-satellite communications, implements a time-sensitive network protocol within the inter-satellite satellite, and performs data communication, which involves the TSN standard. The present invention has low time synchronization requirements while meeting time-sensitive business requirements, and the implementation cost and complexity are reduced compared to the TTE network. The TTE clock synchronization is based on the IEEE 1588 protocol, and its time synchronization accuracy reaches 100ns; the TSN clock synchronization is based on the IEEE802.1AS protocol, and the end-to-end synchronization time is maintained on the devices running and controlling the applications.

Description

Technical Field

[0001] The present invention relates to the field of space information network technology, and in particular to a time synchronization method for integrated inter-satellite and intra-satellite communications based on TSN. Background Art

[0002] With the development of space information networks, new services, especially time-sensitive services, continue to emerge, which puts forward new requirements for information transmission and processing. Space time-sensitive services, namely space surveillance information, space detection information; voice services, video services, etc., put forward higher requirements for the real-time and deterministic nature of data transmission. The real-time nature of space time-sensitive services needs to reach the sub-millisecond level in different occasions, and the deterministic nature requires that each transmission of time-sensitive services adapted to different applications is predictable. In addition, with the increasing complexity of space missions, the strengthening of collaboration between multiple experimental missions has made the requirements for the communication performance of intra-satellite and inter-satellite aerospace information systems increasingly stringent. On the one hand, high bandwidth, high reliability and high real-time nature of the spacecraft intra-satellite information system are required; on the other hand, the spacecraft are networked through inter-satellite links, and the inter-satellite link network should also have the characteristics of low latency, high reliability and high resource utilization. When multiple tasks with large data transmission volumes occupy network resources at the same time, it will cause network delays and network congestion, and reduce data forwarding efficiency. How to ensure the real-time and deterministic nature of intra-satellite Ethernet and inter-satellite link networks is the key to improving network communication performance.

[0003] Time-sensitive networking is a general term for a series of standard technologies. It builds a new network with time characteristics based on traditional Ethernet and provides data transmission capabilities with deterministic latency. TSN integrates key technologies such as time synchronization, flow control, gate control scheduling, and preemption mechanism, and makes appropriate modifications to the traditional Ethernet protocol. It can realize time-sensitive service data transmission based on traditional Ethernet, while ensuring compatibility with ordinary service data transmission, thereby ensuring deterministic latency of data transmission in the network at the link layer.

[0004] However, there are also some severe challenges in directly applying time-sensitive network technology in the aerospace field. For the time-sensitive system of wired and wireless integration, the specific problems are as follows:

[0005] (1) Accuracy and reliability of on-board time synchronization: In the outer space environment of spacecraft, due to the lack of protection from the geomagnetic field, data transmission within the spacecraft is easily affected by outer space radiation, which leads to problems such as insufficient accuracy or stability of the time synchronization results obtained by the time synchronization method used in the time-sensitive network used on the ground. Therefore, how to improve the accuracy and reliability of clock synchronization within the satellite system has become an important issue that needs to be solved.

[0006] (2) Inter-satellite time synchronization accuracy: In a space network environment, spacecraft or satellites are in constant motion, the distance between the propagation paths of two nodes will change, and the space transmission paths are highly asymmetric, so the path delay between nodes cannot be obtained through the measurement method in the IEEE 802.AS protocol. Therefore, how to reduce the impact of the movement of spacecraft or satellites on inter-satellite delay measurement and thus improve the accuracy of inter-satellite time synchronization is a problem that needs to be solved.

[0007] (3) Deterministic delay of inter-satellite data transmission: Due to the time-varying characteristics of inter-satellite transmission links, compared with the fixed ground network, the use of a fixed communication rate between satellites will lead to the problem of end-to-end delay uncertainty. Therefore, how to solve the overall delay uncertainty caused by the change of inter-satellite propagation delay caused by the relative motion of satellites.

[0008] (4) Intra-satellite data transmission delay guarantee problem: Time-sensitive networks can ensure low latency, low jitter, and zero congestion loss for the transmission of critical data streams, so that critical services are not affected by non-critical services. In the TSN IEEE 802.1Qbv protocol, although a scheduling mechanism for gate operations is proposed, which places data in different queues according to priority and then schedules it according to the gate control list to ensure the low latency requirements of critical services, the protocol does not provide a specific method for obtaining the gate control list. Summary of the invention

[0009] In view of this, the present invention provides a time synchronization method for integrated inter-satellite and intra-satellite communications based on TSN, which can implement a time-sensitive network protocol between satellites and within satellites to achieve time synchronization of inter-satellite and intra-satellite data communications.

[0010] To achieve the above purpose, the technical solution of the present invention is as follows:

[0011] The present invention discloses a time synchronization method for integrated inter-satellite and intra-satellite communication based on TSN, which is based on a time-sensitive network. The time-sensitive network includes the TSN standard. The TSN standard includes IEEE 802.1ASbt, IEEE802.1Qbu, IEEE 802.1Qbv, IEEE 802.1Qca, IEEE 802.1Qcc, IEEE 802.1CB, IEEE 802.1Qci and IEEE 802.1Qch protocol; the specific steps of time synchronization are as follows: Step A. By selecting a master clock, establishing a master-slave topology relationship, and establishing a synchronization system in the entire PTP network; Step B. Setting a synchronous local clock scheme, the protocol uses a local clock synchronization algorithm, and calculates the time deviation between the local clock of each slave node and the master clock through the exchange of PTP data messages between the master and slave nodes of the network, and adjusts the local clock to synchronize it with the master clock; Step C. Establishing the overall architecture of a wired and wireless integrated time-sensitive network, obtaining the global topology and resource status information of the satellite network through the TSN controller satellite, and responding to business needs, completing network configuration, routing table distribution and resource reservation, and realizing the delay determinism requirements of integrated intra-satellite and inter-satellite communications; Step D. Establishing a wired and wireless integrated time-sensitive network communication protocol; Step E. Setting intra-satellite time synchronization; Step F. Setting inter-satellite time synchronization.

[0012] Wherein, in the step B, the local clock is synchronized based on the IEEE 1588v1 protocol, and the clocks in the entire PTP network are divided into ordinary clocks and boundary clocks according to the number of PTP communication ports thereon; the local clock is synchronized based on the IEEE 1588v2 protocol; and the local clock is synchronized based on the IEEE 802.1AS protocol.

[0013] When synchronizing the local clock based on the IEEE 1588v1 protocol, the local clock on each port is synchronized with the primary master port; the synchronization system establishment process is as follows:

[0014] 1) In the initial state, each node port will listen to the Sync data frame in the network within the specified time; if a Sync data frame is received, the node port will determine the port state according to the best master clock algorithm;

[0015] If no Sync data frame is received, the node status changes to Pre_Master and assumes itself as the master clock node;

[0016] 2) The port state remains Pre_Master for a certain period of time: If a Sync data frame is received within the specified time of the port, the port state is determined by the best master clock algorithm; if the port is determined to be a master clock, Sync frames will be sent periodically; if it is determined to be a slave clock, Sync frames will be accepted, and the deviation will be calculated to correct the local clock; if the port does not receive a Sync data frame within this period of time, the state will be changed to a master clock and Sync data frames will be sent regularly;

[0017] 3) The status of the master clock and the slave clock changes as the clock performance and operating status change.

[0018] Among them, in the step B, synchronizing the local clock based on the IEEE 1588v2 protocol is an improvement and expansion based on the IEEE 1588v1, and the specific methods are as follows: adding an independent message mode for measuring the network path delay between points; adding a transparent clock model; the transparent clock includes an end-to-end transparent clock and a point-to-point transparent clock; and adding a single-step clock model.

[0019] Wherein, in the step B, the BCMA master clock algorithm is used for synchronizing the local clock based on the IEEE 1588v1 protocol, synchronizing the local clock based on the IEEE 1588v2 protocol, and synchronizing the local clock based on the IEEE 802.1AS protocol.

[0020] Wherein, the step C is divided into the following architecture designs:

[0021] 1) Single-domain wired and wireless integrated time-sensitive network architecture;

[0022] 2) Multi-domain wired and wireless integrated time-sensitive network architecture;

[0023] 3) Establishment and synchronization of dynamic distributed intersatellite network time base.

[0024] Among them, in step D, the TSN protocol modifies the Ethernet-based data link layer, combines clock synchronization and time-sensitive service scheduling to achieve traffic shaping, scheduling and frame preemption, and ensures the bounded transmission of space time-sensitive services within the satellite.

[0025] In the step E, the IEEE 802.1AS protocol is used to ensure the additional requirements of the IEEE 802.3 full-duplex Ethernet link and the IEEE 802.11 wireless network and Ethernet passive optical network.

[0026] Among them, in the step F, the path delay between two nodes is obtained based on multiple measurements of IEEE 802.1AS, and the influence of satellite motion characteristics, relativistic effects and propagation path asymmetry on time synchronization accuracy are comprehensively considered to achieve inter-satellite time synchronization.

[0027] Beneficial effects:

[0028] 1. The present invention studies the corresponding scheduling mechanism algorithms for the business requirements of intra-satellite and inter-satellite communications, implements a time-sensitive network protocol in the inter-satellite and intra-satellite, and performs data communication, which involves the TSN standard. The present invention has low time synchronization requirements while meeting the time-sensitive business requirements, and the implementation cost and complexity are reduced compared to the TTE network. The TTE clock synchronization is based on the IEEE 1588 protocol, and its time synchronization accuracy reaches 100ns; the TSN clock synchronization is based on the IEEE802.1AS protocol, and the end-to-end synchronization time is maintained on the devices running and controlling the applications.

[0029] 2. The network topology of the present invention is flexible, supports the dynamic addition of new services, and reduces the overhead of system re-planning. When a new time-sensitive service is added to the network, TTE needs to re-plan the task and update the time schedule; while TSN only schedules according to the priority of the service and does not need to reallocate resources.

[0030] 3. The data exchange structure of the present invention is simple and effectively reduces data exchange overhead. TTE exchanges time-triggered services and event-triggered services separately, which is equivalent to having two switches working at the same time; TSN does not change the existing Ethernet switch structure and only needs to process data at the output port of the switch.

[0031] 4. The present invention ensures the additional requirements required by IEEE 802.3 full-duplex Ethernet link and IEEE802.11 wireless network and Ethernet passive optical network through IEEE 802.1AS protocol.

[0032] 5. The present invention obtains the path delay between two nodes based on multiple measurements of IEEE 802.1AS, comprehensively considers the influence of satellite motion characteristics, relativistic effects and propagation path asymmetry on time synchronization accuracy, and realizes inter-satellite time synchronization. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 It is a schematic diagram of the overall structure of the present invention;

[0034] Figure 2 is the IEEE 1588 clock synchronization state transition diagram of the present invention;

[0035] Figure 3 It is the PTP synchronization principle of the present invention;

[0036] Figure 4 It is a schematic diagram of the point-to-point delay measurement principle of the present invention;

[0037] Figure 5This is a single-domain wired and wireless integrated time-sensitive network architecture diagram of the present invention;

[0038] Figure 6 This is a diagram of the multi-domain wired and wireless integrated time-sensitive network architecture of the present invention;

[0039] Figure 7 is a schematic diagram of a delay measurement mechanism of the present invention;

[0040] Figure 8 It is a clock synchronization measurement flow chart of the present invention. DETAILED DESCRIPTION

[0041] The present invention is described in detail below with reference to the accompanying drawings and embodiments.

[0042] The present invention provides a time synchronization method for integrated inter-satellite and intra-satellite communication based on TSN, based on a time-sensitive network, the time-sensitive network includes the TSN standard, and the TSN standard includes IEEE 802.1ASbt, IEEE802.1Qbu, IEEE 802.1Qbv, IEEE 802.1Qca, IEEE 802.1Qcc, IEEE 802.1CB, IEEE 802.1Qci and IEEE 802.1Qch protocols. The specific steps of the time synchronization method of the present invention are as follows:

[0043] Step A. Select the synchronization system. Since the IEEE 802.1ASbt protocol is simplified and modified based on the IEEE 1588 protocol, it is also referred to as the Precision Time Protocol PTP. The protocol uses the best master clock algorithm, selects the master clock, establishes the master-slave topology relationship, and establishes a synchronization system in the entire PTP network.

[0044] Step B. Set up a synchronized local clock scheme. The protocol uses a local clock synchronization algorithm. Through the exchange of PTP data messages between the master and slave nodes in the network, the time deviation between the local clock of each slave node and the master clock is calculated, and the local clock is adjusted to synchronize with the master clock. The details are as follows:

[0045] Based on the IEEE 1588v1 protocol, the local clock is synchronized. The clocks in the entire PTP network can be divided into ordinary clocks and boundary clocks according to the number of PTP communication ports on it. Based on the IEEE 1588v2 protocol, the local clock is synchronized. Based on the IEEE802.1AS protocol, the local clock is synchronized.

[0046] Step C. Establish the overall architecture of the wired and wireless integrated time-sensitive network, obtain the global topology and resource status information of the satellite network through the TSN controller satellite, respond to business needs, complete network configuration, routing table distribution and resource reservation, etc., and realize the time delay determinism requirements of integrated intra-satellite and inter-satellite communications;

[0047] Step D. Establish a wired and wireless integrated time-sensitive network communication protocol. The TSN protocol modifies the Ethernet-based data link layer and combines clock synchronization and time-sensitive service scheduling to achieve traffic shaping, scheduling, frame preemption, etc., to ensure the time-bounded transmission of space time-sensitive services within the satellite;

[0048] Step E. Setting up intra-satellite time synchronization, ensuring the additional requirements required for IEEE 802.3 full-duplex Ethernet links and IEEE 802.11 wireless networks and Ethernet passive optical networks through IEEE 802.1AS protocol;

[0049] Step F: Set up inter-satellite time synchronization. Based on IEEE 802.1AS, obtain the path delay between two nodes through multiple measurements. Consider the influence of satellite motion characteristics, relativistic effects, propagation path asymmetry, etc. on time synchronization accuracy to achieve inter-satellite time synchronization.

[0050] In step B, the local clock is synchronized based on the IEEE 1588v1 protocol. The clocks in the entire PTP network can be divided into ordinary clocks and boundary clocks according to the number of PTP communication ports on it: there is only one ordinary clock, while there are multiple boundary clocks. Boundary clocks are generally used at network nodes with low determinism, such as switches or routers, which are generally used as boundary clocks. Figure 1 As shown in the figure, PTP communication is performed independently on each port. Specifically, only one slave port is allowed on the boundary clock to communicate with the master port of the upper node and synchronize its local clock with the master port of the lower node. The remaining ports are master ports that communicate with the slave ports of the downstream nodes. The boundary clock can be connected to different network protocols, and the synchronization system establishment process is as follows:

[0051] 1) In the initial state, each node port will listen to the Sync data frame in the network within the specified time; if a Sync data frame is received, the node port will determine the port state according to the best master clock algorithm;

[0052] If no Sync data frame is received, the node status changes to Pre_Master and assumes itself as the master clock node. At this time, the node port status is the master clock, but no Sync frame is sent.

[0053] 2) The port state remains Pre_Master for a certain period of time: If a Sync data frame is received within the specified time of the port, the port state is determined by the best master clock algorithm. If the port is determined to be a master clock, Sync frames will be sent periodically; if it is determined to be a slave clock, Sync frames will be accepted, and the deviation will be calculated to correct the local clock.

[0054] If the port does not receive a Sync data frame within this time period, the state is changed to the master clock and the Sync data frame is started to be sent regularly.

[0055] 3) The status of the master clock and the slave clock changes with the change of clock performance and operating status. Figure 2 Demonstrates state transitions in BMCA.

[0056] In the step B, synchronizing the local clock based on the IEEE 1588v2 protocol is an improvement and extension based on the IEEE 1588v1, and the specific methods are as follows: adding an independent message mode for measuring the network path delay between points; adding a transparent clock model; the transparent clock includes an end-to-end transparent clock and a point-to-point transparent clock; and adding a single-step clock model.

[0057] In the step B, the BCMA master clock algorithm is used in synchronizing the local clock based on the IEEE 1588v1 protocol, synchronizing the local clock based on the IEEE 1588v2 protocol, and synchronizing the local clock based on the IEEE 802.1AS protocol.

[0058] The PTP synchronization principle of the present invention is as follows Figure 3 As shown in the figure, the time offset adjustment implementation mechanism is as follows: the slave node receives the Sync data frame and records the receiving time T2 and the Follow_Up frame with the Sync frame sending time information T1. In addition, the slave node will send the Delay_Req data frame to the master node and record the sending time T3, and then receive the feedback frame Delay_Resp from the master node, which carries the time T4 when the master node receives the Delay_Req frame, and the four timestamps T1-T4 obtained from the clock. Assuming that the time offset between the master and slave nodes and the transmission delay on the path are Offsett and Delay respectively, the following equation can be obtained:

[0059] T2=Offest+Delay+T1 (1)

[0060] T4=T3-Offset+Delay (2)

[0061] According to the above formula (1) and formula (2), the Offset and Delay values ​​are calculated:

[0062] Delay=[(T2-T1)+(T4-T3)] / 2 (3)

[0063] Offset=[(T2-T1)-(T4-T3)] / 2 (4)

[0064] The slave node device adjusts the local time accordingly to achieve clock synchronization between the master and slave devices.

[0065] The time synchronization algorithm of the PTP v1 protocol can achieve sub-microsecond accuracy, but it depends on the symmetry of the links between network nodes. For asymmetric link delays in the network, an additional asymmetric algorithm is needed to calculate the round-trip transmission delay difference and compensate for the link delay. Figure 4 shown.

[0066] In step C, the architecture design is as follows:

[0067] 1) Single-domain wired and wireless integrated time-sensitive network architecture: In a single satellite subnet, in order to meet the latency-bounded communication requirements within the subnet, a satellite is selected to act as a TSN controller to obtain global status information within the subnet and issue decisions. Figure 5 As shown in the figure, this architecture mainly adopts the idea of ​​separation of control plane and data plane, in which the TSN controller satellite is mainly responsible for satellite network topology discovery, traffic monitoring and forwarding information table configuration. The specific work flow of the control plane is as follows: when a new data stream or service request is added, the TSN controller satellite calculates based on the obtained topological status information and service latency requirements; and sends the obtained network configuration parameters to the satellites in the subnet (red dotted line); the satellites in the subnet can use the corresponding strategy when forwarding the TSN stream according to the received configuration information; finally, the data plane forwards the TSN data stream according to the decision of the control plane (green dotted line).

[0068] 2) Multi-domain wired and wireless integrated time-sensitive network architecture: A single-domain wired and wireless integrated time-sensitive network architecture can only meet the communication needs within a subnet. When the network scale becomes larger, due to the limited coverage and control capabilities of a TSN controller satellite, it is impossible to obtain the topological status information of the entire network. Therefore, for large-scale TSN satellite networks (such as satellites at different orbital altitudes), a multi-domain wired and wireless integrated time-sensitive network architecture is proposed. Figure 6 As shown, a TSN controller satellite is selected in each subnet. These TSN controller satellites can obtain the topology and resource status information of the entire network through information interaction, thereby providing latency deterministic services for time-sensitive services during cross-domain transmission.

[0069] 3) Establishment and synchronization of time reference in dynamic distributed intersatellite network: In the integrated wired and wireless satellite network architecture, scheduling and configuration and other related decisions are issued through the TSN controller. However, how to select the satellite node representing the TSN controller in the dynamic distributed satellite network. Taking intersatellite time synchronization as an example, in order to establish a time reference for time synchronization in a dynamic distributed satellite network, a method for selecting the time reference center with the shortest synchronization time for the entire network is proposed, and all satellites are synchronized to this reference.

[0070] For a time synchronization network, when all satellites in the network are synchronized, the time required for synchronization of the satellite farthest from the reference center is longer than that of other satellites. The so-called distance refers to the length of the information propagation delay between two satellites. For example, the distance between two satellites with a direct communication link is the propagation delay between the two satellites; and the distance between two satellites without a direct link is the sum of the propagation delays of several links. If the distance of the satellite farthest from the reference center in the entire network is smaller, the time spent on time synchronization of the entire network will be less, and the performance will be better.

[0071] Based on the above analysis, for a network topology, starting from point i, find the shortest delay path to any satellite in the network, and select the longest delay path, which is the minimum time for the entire network to complete time synchronization with point i as the synchronization center. The following objective function can be obtained:

[0072] min(T i ) (5);

[0073] Where T i It means the minimum time for the entire network to complete time synchronization with i as the synchronization center. Similarly, the objective function can be transformed into:

[0074]

[0075] Among them, H i,j represents the set of all possible synchronization delays from i to j. By determining the minimum maximum path delay from satellite i, the delay required for the entire network to complete time synchronization when i is used as the synchronization reference center can be determined. The delay measurement mechanism schematic diagram of the present invention is shown in Figure 7 By comparison, the best synchronization reference center in the network can be found. The clock synchronization measurement flow chart of the present invention is shown in FIG. Figure 8 shown.

[0076] The present invention is simulated and verified using the EXata 5.1 simulated satellite network. The IEEE 802.1AS time synchronization protocol in the TSN protocol cluster developed in Exata is tested and the results are analyzed. In the test scenario, the wired network is based on IEEE802.3 full-dual Ethernet to develop the 802.1AS protocol. The verification results show that the method of the present invention effectively realizes time synchronization.

[0077] In summary, the above are only preferred embodiments of the present invention and are not intended to limit the protection scope of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A time synchronization method for integrated inter-satellite and intra-satellite communications based on TSN, characterized in that: Based on a time-sensitive network, the time-sensitive network includes the TSN standard, and the TSN standard includes IEEE 802.1ASbt, IEEE802.1Qbu, IEEE 802.1Qbv, IEEE 802.1Qca, IEEE 802.1Qcc, IEEE 802.1CB, IEEE 802.1Qci and IEEE 802.1Qch protocols; the specific steps of the time synchronization are as follows: Step A. By selecting a master clock, a master-slave topology relationship is established, and a synchronization system is established in the entire PTP network; Step B. A synchronization local clock scheme is set up, and the protocol uses a local clock synchronization algorithm, and the time deviation between the local clock of each slave node and the master clock is calculated through the exchange of PTP data packets between the master and slave nodes of the network, and the local clock is adjusted to synchronize with the master clock; Step C. Establish the overall architecture of the integrated wired and wireless time-sensitive network, obtain the global topology and resource status information of the satellite network through the TSN controller satellite, respond to business needs, complete network configuration, routing table distribution and resource reservation, and realize the time delay determinism requirements of integrated intra-satellite and inter-satellite communication; Step D. Establish the integrated wired and wireless time-sensitive network communication protocol; Step E. Set up intra-satellite time synchronization; Step F. Setting inter-satellite time synchronization; in the step B, synchronizing the local clock based on the IEEE 1588v1 protocol, the clocks in the entire PTP network are divided into ordinary clocks and boundary clocks according to the number of PTP communication ports thereon; Synchronize local clock based on IEEE 1588v2 protocol; Synchronize local clock based on IEEE 802.1AS protocol; When synchronizing the local clock based on the IEEE 1588v1 protocol, the local clock on each port is synchronized with the master port; the synchronization system establishment process is as follows: 1) In the initial state, each node port will listen to the Sync data frame in the network within the specified time; if a Sync data frame is received, the node port will determine the port state according to the best master clock algorithm; If no Sync data frame is received, the node status changes to Pre_Master and assumes itself as the master clock node; 2) The port state remains Pre_Master for a certain period of time: If a Sync data frame is received within the specified time of the port, the port state is determined by the best master clock algorithm; if the port is determined to be the master clock, Sync frames will be sent periodically; If it is determined to be a slave clock, it accepts the Sync frame, calculates the deviation, and corrects the local clock; If the port does not receive a Sync data frame within this time period, it changes its state to the master clock and starts to send Sync data frames regularly. 3) The status of the master clock and the slave clock changes with the change of clock performance and operating status; In the step B, synchronizing the local clock based on the IEEE 1588v2 protocol is an improvement and extension based on the IEEE 1588v1, and the specific methods are as follows: adding an independent message mode for measuring the network path delay between points; adding a transparent clock model; the transparent clock includes an end-to-end transparent clock and a point-to-point transparent clock; and adding a single-step clock model.

2. The method according to claim 1, characterized in that In the step B, the BCMA master clock algorithm is used in synchronizing the local clock based on the IEEE 1588v1 protocol, synchronizing the local clock based on the IEEE 1588v2 protocol, and synchronizing the local clock based on the IEEE 802.1AS protocol.

3. The method according to claim 2, characterized in that In step C, the architecture design is as follows: 1) Single-domain wired and wireless integrated time-sensitive network architecture; 2) Multi-domain wired and wireless integrated time-sensitive network architecture; 3) Establishment and synchronization of dynamic distributed intersatellite network time base.

4. The method according to claim 3, characterized in that In step D, the TSN protocol modifies the Ethernet-based data link layer and combines clock synchronization and time-sensitive service scheduling to implement traffic shaping, scheduling, and frame preemption, thereby ensuring the bounded transmission of space time-sensitive services within the satellite.

5. The method according to claim 2 or 4, characterized in that In step E, the additional requirements required by the IEEE 802.3 full-duplex Ethernet link and the IEEE 802.11 wireless network and Ethernet passive optical network are ensured through the IEEE 802.1AS protocol.

6. The method according to claim 5, characterized in that In step F, the path delay between two nodes is obtained by multiple measurements based on IEEE 802.1AS, and the influence of satellite motion characteristics, relativistic effects and propagation path asymmetry on time synchronization accuracy is comprehensively considered to achieve inter-satellite time synchronization.

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