Data transmission method and system based on satellite time synchronization and dynamic time slot allocation

Abstract

The invention discloses a data transmission method and system based on satellite time synchronization and dynamic time slot allocation. The method comprises the following steps: a terminal side sends a detection message to a plurality of sub-network nodes in a network at an application layer; each subnet node reports dynamic information according to the current node state after receiving the detection message; and the terminal side carries out message fragmentation and time slot division on an application layer according to the report information of each node, formulates a data packet transmission strategy, and carries out data transmission based on the data packet transmission strategy. According to the method, global network resources are collected through resource awareness, on-demand transmission is carried out based on network slices, in the data transmission process, a data packet loss and retransmission mechanism can be dynamically adjusted, the method can better adapt to various complex communication scenes, and reliable transmission of data in various complex battlefield environments is ensured.

Description

Technical Field

[0001] The present invention relates to the technical field of tactical communications, and in particular to a data transmission method and system based on satellite time synchronization and dynamic time slot allocation. Background Art

[0002] Wireless communication is the most widely used communication method in tactical communication. Compared with conventional civilian communication networks, tactical communication networks have higher latency, greater packet loss rate and lower bandwidth. For example, two friendly combat troops far apart need to cross mountains for wireless communication, which will be affected by electromagnetic interference. In addition, the position of the mobile troops is constantly changing, and the network topology will be constantly adjusted accordingly. The network status and network resources are dynamically changing, and there are usually many problems such as unstable routing, increased packet loss rate and latency, slow protocol convergence, and network congestion.

[0003] In order to ensure the stability of tactical wireless communication, satellite communication or unmanned relay communication is usually used to back up the communication link. However, the bandwidth of satellite links is limited, and unmanned relay communication is greatly affected by the battlefield environment. It cannot be flexibly applied in some special scenarios, and it will increase the complexity of the communication network. When the tactical communication network is successfully established, the service will be transmitted according to demand. Some high-speed mobile nodes have high real-time requirements, but the service cannot be differentiated by sensing network resources. This may cause other services to use network bandwidth resources at the same time. For example, if multiple friendly troops are attacked by enemy fire at the same time, multiple nodes will compete for the use of network bandwidth resources at the same time, resulting in the limited bandwidth being occupied by multiple services, which may cause network paralysis in severe cases. The traditional approach is to optimize the physical and network layer transmission performance of the network to improve the overall performance of the communication network. By adding multiple communication paths, the service is transmitted in a multipath manner, but this method requires the addition of multiple transmission equipment, which will increase the cost of equipment to a certain extent, cause waste of communication resources, and reduce the reliability of the entire communication system.

[0004] Therefore, the present application proposes a reliable data transmission method and system based on satellite time synchronization and dynamic time slot allocation, which can dynamically adjust the service transmission mode according to the overall network resource status, and improve the reliability of service transmission from the perspective of the service domain. Summary of the invention

[0005] In view of this, the present invention provides a data transmission method and system based on satellite time synchronization and dynamic time slot allocation, which is used to solve the technical problems that when optimizing the tactical communication network, only the physical and network layer transmission performance of the network is optimized, while the exploration and improvement of the communication network performance from the business field is ignored, resulting in large competition for overall performance bandwidth resources, communication congestion and paralysis.

[0006] In order to achieve the above technical objectives, the present invention adopts the following technical solutions:

[0007] The present invention provides a data transmission method based on satellite time synchronization and dynamic time slot allocation, comprising:

[0008] The terminal side sends detection messages to multiple subnet nodes in the network at the application layer;

[0009] After receiving the detection message, each subnet node reports dynamic information according to the current node status;

[0010] The terminal side performs message fragmentation and time slot division at the application layer according to the reporting information of each node, formulates a data packet transmission strategy, and performs data transmission based on the data packet transmission strategy.

[0011] Furthermore, the terminal-side application layer and the subnet node communicate with each other via a preset resource-aware protocol;

[0012] The detection message of the preset resource perception protocol includes a first message type sent from a source node to a destination node, and a second message type sent from a destination node to a source node; each node updates relevant fields in the detection message according to resource information collected during subnet networking;

[0013] The resource information includes the satellite synchronization time of each node, the bandwidth resources of each subnet, the number of nodes of each subnet and the MTU value of each node.

[0014] Furthermore, each node updates the relevant fields in the detection message according to the resource information collected during the subnet networking, including:

[0015] When the detection message is of the first message type, the source end node sends an initial detection message to a first relay node on a path to the destination end node;

[0016] The first relay node updates the initial detection message, obtains the minimum value of each resource information, and searches for a feasible path to select an outbound interface to forward the updated detection message to the next relay node;

[0017] Each relay node updates the resource field in the acquired detection message according to the resource information collected during networking, and updates the minimum value of each resource information until the detection message is sent to the destination node.

[0018] Furthermore, the structure of the detection message includes satellite time, data header and valid data;

[0019] The satellite time is used for time synchronization and also for generating the seed parameters of the key to encrypt the data header and valid data of the message;

[0020] During the data transmission process, the data header and valid data are transmitted in an encrypted manner, and the satellite time is transmitted in an unencrypted manner.

[0021] Furthermore, the working state of the terminal side application layer in data interaction includes:

[0022] Decryption state, in the state of receiving and decrypting the message to be sent;

[0023] The data packet processing state is in the state of determining whether the message needs to be fragmented and checking whether the data is wrong;

[0024] The message sending status indicates that when the data check result is correct, the message is fragmented according to the MTU value, and data is sent after the sent time slot arrives. The message sending is completed after the feedback information is received.

[0025] Furthermore, the terminal side performs message fragmentation and time slot division at the application layer according to the reporting information of each node, including:

[0026] The message is fragmented based on the minimum MTU value of the current subnet node, so that the size of each message slice does not exceed the minimum MTU value of the subnet node;

[0027] The calculation formula for the optimal time slot length of each node in the subnet is:

[0028]

[0029] Among them, T best represents the optimal time slot length of each node, M min Indicates the minimum MTU value of the current subnet node, R c Indicates the current number of network resources of each node.

[0030] Furthermore, the terminal side formulates a data packet transmission strategy at the application layer according to the reported information of each node, including:

[0031] Allocate time slots based on the effective bandwidth resources of the current subnet, so that the number of effective resources of each node is less than the minimum network resources available in the current subnet node;

[0032] The calculation formula for the number of effective resources of each node is:

[0033]

[0034] Among them, R v <R min , R min Indicates the number of effective resources of each node on the minimum network resources available in the current subnet node, R v Indicates the number of effective resources of each node, Tbest represents the optimal time slot length of each node, M min Indicates the minimum MTU value of the current subnet node, T c Indicates the current time slot length of each node.

[0035] Further, performing data transmission based on the data packet transmission strategy includes:

[0036] Acquire and store a time slot allocation table containing multiple nodes, traverse the time slot allocation table, and fill in the current satellite time as the sending time in the idle time slot;

[0037] When response data is received, the current data cache is traversed to determine whether there is a timestamp equal to the timestamp in the received response message header; if so, it is confirmed that the received message is an acknowledgment of the sent message and the current data cache resources are released; if the current message is a message to be sent and there is no available sending time slot, the message is stored in the queue and waits for the next available time slot to be sent again.

[0038] The present invention also provides a data transmission system based on satellite time synchronization and dynamic time slot allocation, comprising a plurality of communication terminals, wherein the plurality of communication terminals are connected by a plurality of subnets of different types; each communication terminal is deployed with a service processing module at the application layer; the service processing module uses the data transmission based on satellite time synchronization and dynamic time slot allocation as described in any of the above technical solutions to perform data communication.

[0039] Furthermore, the types of the subnet include at least non-IP network, full IP network and single-soldier network.

[0040] Compared with the prior art, the advantages of the present invention are:

[0041] 1) In combination with the business needs of actual application scenarios, optimize network transmission performance from the perspective of the business domain to adapt to tactical communication scenarios with high latency, high packet loss rate and easy interception, and improve the communication performance of wireless networks from the source of business.

[0042] 2) Optimize network transmission performance from the perspective of the business domain at the application layer. The terminal sends detection messages to multiple subnet nodes at the application layer, allowing each subnet node to report dynamic information based on the current status. It can collect status information of each node in real time and more accurately perceive the link available resources of the transmission service, so that the network can adapt to different network environments and achieve dynamic adjustment. It is suitable for tactical communication solutions with high latency, high packet loss rate and easy interception.

[0043] 3) Message fragmentation and time slot division based on node status information helps avoid transmission delays and packet loss caused by large data packets in high-load, low-bandwidth or high-latency network environments. It also avoids multiple nodes competing for bandwidth at the same time, helps reduce conflicts and collisions, and improves the concurrency of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 A schematic flow chart of a data transmission method based on satellite time synchronization and dynamic time slot allocation provided by the present invention;

[0045] Figure 2 A schematic diagram of the framework of the resource awareness protocol provided by the present invention;

[0046] Figure 3 A schematic diagram of the resource awareness protocol flow provided by the present invention;

[0047] Figure 4 A schematic diagram of the state transition of the information processing mechanism provided by the present invention;

[0048] Figure 5 A schematic diagram of time slot allocation provided by the present invention;

[0049] Figure 6 A schematic diagram of a data transmission process based on time slots provided by the present invention;

[0050] Figure 7 A schematic diagram of an information communication application architecture in a wireless communication environment provided by the present invention;

[0051] Figure 8 A schematic diagram of wireless communication simulation based on OPNET provided by the present invention;

[0052] Fig. 9 A schematic diagram showing a comparison of simulation results of message transmission success rates of different byte lengths provided by the present invention;

[0053] Fig.10 A schematic diagram showing the comparison of simulation results of message transmission rates under different network scales provided by the present invention;

[0054] Fig.11 A schematic diagram showing the comparison of simulation results of data success rates at different message transmission intervals provided by the present invention;

[0055] Fig.12 A schematic diagram showing the simulation results of data transmission delays for different message lengths provided by the present invention;

[0056] Fig.13 A schematic diagram showing the comparison of simulation results of end-to-end data delay under different MTU values ​​provided by the present invention. DETAILED DESCRIPTION

[0057] The preferred embodiments of the present invention are described in detail below in conjunction with the accompanying drawings, wherein the accompanying drawings constitute a part of this application and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not used to limit the scope of the present invention.

[0058] The present invention provides a data transmission method based on satellite time synchronization and dynamic time slot allocation, which is specifically described below.

[0059] See also Figure 1 This embodiment provides a data transmission method based on satellite time synchronization and dynamic time slot allocation, including:

[0060] Step S101: The terminal side sends a detection message to multiple subnet nodes in the network at the application layer;

[0061] Step S102: After receiving the detection message, each subnet node reports dynamic information according to the current node status;

[0062] Step S103: The terminal side performs message segmentation and time slot division at the application layer according to the reporting information of each node, formulates a data packet transmission strategy, and performs data transmission based on the data packet transmission strategy.

[0063] The method of this embodiment optimizes the network transmission performance from the perspective of the service domain at the application layer. The terminal sends a detection message to multiple subnet nodes at the application layer, allowing each subnet node to report dynamic information according to the current status, so that the status information of each node can be collected in real time, and the link available resources of the transmission service can be more accurately perceived, so that the network can adapt to different network environments and achieve dynamic adjustment. It is suitable for tactical communication solutions with high latency, high packet loss rate and easy interception. Message segmentation and time slot division based on the node status information helps to avoid transmission delays and packet loss caused by excessively large data packets in a high-load, low-bandwidth or high-latency network environment, and also avoids multiple nodes competing for bandwidth at the same time, which helps to reduce conflicts and collisions and improves the concurrency of the system. This method improves the communication performance of the tactical wireless network from the source of the service, can more accurately perceive the link available resources of the service that needs to be transmitted, so as to better perform network slicing, provide a more accurate reference for service transmission, and then optimize the comprehensive performance of the tactical wireless communication network.

[0064] As a preferred embodiment, the terminal side application layer and the subnet node communicate via a preset resource awareness protocol;

[0065] The detection message of the preset resource perception protocol includes a first message type sent from a source node to a destination node, and a second message type sent from a destination node to a source node; each node updates relevant fields in the detection message according to resource information collected during subnet networking;

[0066] The resource information includes the satellite synchronization time of each node, the bandwidth resources of each subnet, the number of nodes of each subnet and the MTU value of each node.

[0067] Since the network status and network resources in tactical communication scenarios are dynamically changing, when transmitting services, it is necessary to dynamically perceive network resources and determine the transmission mode of the service based on the current resource status. Figure 2 As shown in the figure, the application layer obtains information such as time slot division, MTU and minimum available bandwidth resources of each subnet through node reporting information, and formulates differentiated data transmission control strategies based on this information, so that messages can be sent according to the available resources of the network. Before transmitting the message, the application layer data processing module detects the global resource availability of the network through the resource perception protocol, and then fragments the message based on the available resource information; each subnet dynamically reports the number of nodes existing in the current subnet, and the application layer module divides the time slot according to the number of nodes, and combines the minimum available bandwidth resources of the entire network to comprehensively calculate the optimal transmission strategy of the message, and then transmits the message.

[0068] In order to improve the security of data transmission in tactical communication scenarios, encryption will be performed during message transmission. Satellite time will be used as the seed for negotiating key calculation between two nodes, and the data header and valid data of the message will be encrypted. During data transmission, the data header and valid data are transmitted in encrypted mode, and the satellite time is transmitted in unencrypted mode.

[0069] As a preferred embodiment, each node updates the relevant fields in the detection message according to the resource information collected during the subnet networking, including:

[0070] When the detection message is of the first message type, the source end node sends an initial detection message to a first relay node on a path to the destination end node;

[0071] The first relay node updates the initial detection message, obtains the minimum value of each resource information, and searches for a feasible path to select an outbound interface to forward the updated detection message to the next relay node;

[0072] Each relay node updates the resource field in the acquired detection message according to the resource information collected during networking, and updates the minimum value of each resource information until the detection message is sent to the destination node.

[0073] Specifically, Figure 3 As shown, Figure 3In the figure, A, B, C, and D are four switching nodes in the network. When information needs to be transmitted between the terminals corresponding to A and D, the wireless subnet or wired subnet will have synchronous information exchange during the networking process. During this period, each node will collect information, such as subnet node information, MTU, and available resources of channels with wireless devices. Each node will store this information. The application layer sends detection messages between the source and destination ends where data needs to be sent to perceive this network resource information.

[0074] The application terminal connected to node A will first send a detection message for resource perception detection. The minimum resource initial value in the message is infinite. After receiving the detection message, node A will find the outbound interface according to the route, and then find the resource information of the subnet connected to the outbound interface according to the outbound interface. The corresponding fields in the detection message are updated through the relevant resource information of the subnet. Figure 3 Min(A,+∞) means taking the minimum value between A and ∞, Min(A,B) means taking the minimum value between A and B, and Min(A,B,C) means taking the minimum value between A, B, and C. A / B / C includes the stored bandwidth, the minimum MTU value, and the number of nodes contained in the current subnet. By reporting the minimum MTU value, the delay caused by data fragmentation in the intermediate subnet can be reduced. By reporting the number of nodes, a basis can be provided for the application layer to divide time slots. By reporting bandwidth resource information, information support can be provided for the application layer to perform network slicing.

[0075] The entire detection message goes back and forth between the source and the destination terminal, and the detection is performed on demand according to the needs of user data transmission. The information carried by the message occupies less bandwidth, and the detection message is not frequently transmitted in the network, so the overall resource consumption of the network is also small. By using the reserved resource information obtained by the wireless subnet and reporting it through the subnet-related nodes, the resource status of each subnet is collected and centrally reported, so that the resource status view of the global network is obtained at the application layer, providing decision support for application layer data transmission.

[0076] As a preferred embodiment, the working state of the terminal side application layer in data interaction includes:

[0077] Decryption state, in the state of receiving and decrypting the message to be sent;

[0078] The data packet processing state is in the state of determining whether the message needs to be fragmented and checking whether the data is wrong;

[0079] The message sending status indicates that when the data check result is correct, the message is fragmented according to the MTU value, and data is sent after the sent time slot arrives. The message sending is completed after the feedback information is received.

[0080] like Figure 4 As shown, Figure 4 The following diagram shows the state transition of the application layer message processing module in the process of receiving and sending messages. n0 Indicates that the module receives the message to be sent and decrypts the message; S 01 Indicates that the received message is a fragmented message; S 10 Indicates that the data packet is wrong or lost and needs to be retransmitted; S 03 Indicates that the data packet does not need to be fragmented; S 13 Indicates that the data packet is successfully received; S 12 and S 32 Indicates that the data packet is wrong and needs to be discarded; S 34 Indicates that the message is correct and enters the next stage of processing; S 45 Indicates the process of sending a message; S 56 Indicates that fragmentation is required according to the interface MTU; S 67 Indicates that a fragment message has been received; S 78 Indicates that the fragmentation is completed and waiting for the time slot to be sent; S 88 Indicates the time slot where the current message is located; S 89 Indicates that the current message time slot has arrived and the message has started to be sent; S 98 Indicates the time slot for waiting for a message to be sent; S 9n Indicates that the data is successfully sent from the interface connected to the node to the network; S n9 Indicates that confirmation feedback is received after the message is sent, and the message is finally sent.

[0081] As a preferred embodiment, the terminal side performs message fragmentation and time slot division at the application layer according to the reporting information of each node, including:

[0082] The message is fragmented based on the minimum MTU value of the current subnet node, so that the size of each message slice does not exceed the minimum MTU value of the subnet node;

[0083] The calculation formula for the optimal time slot length of each node in the subnet is:

[0084]

[0085] Among them, T best represents the optimal time slot length of each node, M min Indicates the minimum MTU value of the current subnet node, R c Indicates the current number of network resources of each node.

[0086] The terminal side formulates a data packet transmission strategy at the application layer based on the reported information of each node, including: allocating time slots based on the effective bandwidth resources of the current subnet, so that the number of effective resources of each node is less than the minimum network resources available in the current subnet node;

[0087] The calculation formula for the number of effective resources of each node is:

[0088]

[0089] Among them, R v <R min , R min Indicates the number of effective resources of each node on the minimum network resources available in the current subnet node, R v Indicates the number of effective resources of each node, T best represents the optimal time slot length of each node, M min Indicates the minimum MTU value of the current subnet node, T c Indicates the current time slot length of each node.

[0090] To better illustrate the time slot allocation on the device terminal, see Figure 5 , Figure 5 The time slot allocation of the corresponding subnet when the terminal is connected to each node is shown. The entire network includes a backbone network and an access network, where some backbone network nodes and access network nodes form a subnet. Assuming that each unit time can be divided into 12 time slots, subnet S_Net 1 includes nodes 1, 3, 4 and 5, which are allocated on time slots 1, 3, 4 and 5 respectively, spanning three cycles; subnet S_Net 2 includes nodes 1 and 2, which are allocated on time slots 1 and 2 respectively, spanning six cycles; subnet S_Net 3 includes nodes 2, 6 and 7, which are allocated on time slots 2, 6 and 7 respectively, spanning four cycles.

[0091] When transmitting messages between nodes, the application layer module strictly transmits messages according to the time slot allocation. Figure 6 middle, Figure 6 In the figure, the horizontal axis represents the time slot number, taking nine time slots as an example, and the vertical axis represents the order in which messages are sent. Message 1 is sent in the first time slot, and message 2 is sent in the fourth time slot. At this time, message 1 has not been sent (as long as the transmission is not confirmed to be completed, it is considered unsent), and message 3 is sent in the seventh time slot. After message 1 receives the confirmation message and releases the required resources, the first time slot can be used to send the fourth message. Similarly, after sending the second message, the fourth time slot can be used to send the fifth message. It can be seen that as long as the time slot design is reasonable, the reliable transmission confirmation mechanism of the message will not affect the real-time performance of message sending.

[0092] As a preferred embodiment, data transmission based on the data packet transmission strategy includes:

[0093] Acquire and store a time slot allocation table containing multiple nodes, traverse the time slot allocation table, and fill in the current satellite time as the sending time in the idle time slot;

[0094] When response data is received, the current data cache is traversed to determine whether there is a timestamp equal to the timestamp in the received response message header; if so, it is confirmed that the received message is an acknowledgment of the sent message and the current data cache resources are released; if the current message is a message to be sent and there is no available sending time slot, the message is stored in the queue and waits for the next available time slot to be sent again.

[0095] Specifically, after the time slot allocation is completed, the service message needs to add the timestamp sent along with the message obtained by the satellite synchronization time to the message header before sending, and ensure the correctness of message sending and receiving through collaborative packaging or confirmation.

[0096] This embodiment also provides a data transmission system based on satellite time synchronization and dynamic time slot allocation, including multiple communication terminals, which are connected by multiple subnets of different types; each communication terminal is deployed with a service processing module at the application layer; the service processing module uses the data transmission based on satellite time synchronization and dynamic time slot allocation as described in any of the above technical solutions to perform data communication.

[0097] As a preferred embodiment, the types of the subnet include at least a non-IP network, an all-IP network and a single-soldier network.

[0098] like Figure 7 As shown in the figure, by flexibly deploying the service processing module on the application terminal, the service transmission strategy is formulated in combination with the currently available communication link resources in the network. Therefore, the transmission strategy of the service before transmission is already in the optimal state. At the same time, the service uses the network itself as a transparent link during the transmission process, and each node in the communication network will not intervene too much in the service transmission strategy, reducing unnecessary service processing delays and queuing delays in the network. Combined with the reliable transmission mechanism of the service processing module itself, the success rate of service transmission is improved, and the service is transmitted according to the available network resources to ensure the overall performance of the network.

[0099] In order to verify the actual technical effect of the present invention, Figure 8 As shown in the figure, we built a tactical communication network with multi-level wireless subnets in OPNET to verify its transmission performance in CSMA mode and under different retransmission strategies, including simulating network transmission performance under different packet loss rates, network transmission performance under different network scales, and network transmission performance under different time slot allocations, and compared the transmission performance of traditional tactical wireless communications that do not adopt this solution.

[0100] In the constructed tactical communication network, each vehicle node contains a radio station and a router device. All nodes are synchronized through satellites. In order to reduce the overhead of the radio station link, the router device runs the RIP routing protocol, which is used for different router devices to perform routing networking through the radio station link, thereby realizing the establishment of the underlying link, and running the resource reporting module program in each vehicle node. Set the bandwidth, node MTU, network mode and other parameters of the transmission link in the simulation network; the node runs the program module designed in this scheme on each computer and handheld terminal at the same time.

[0101] Fig. 9 The simulation results of the transmission success rate between two nodes in the same subnet when the MTU value is set to 128 are shown. By sending 1000 data packets, the average message transmission success rate of this scheme under the same message length under different retransmission conditions is simulated. The simulation results show that as the length of the data packet gradually increases, the performance of the traditional scheme decreases more significantly. However, when the message length of the data packet is the same, the data transmission success rate of this scheme gradually increases with the increase in the number of retransmissions. When the length of the sent data packet is less than 600, the data transmission has a higher success rate when the number of retransmissions is set to 2 or 3. Therefore, under the same conditions, this scheme has better data transmission performance advantages than the traditional scheme.

[0102] When the number of nodes in the subnet is different, the time slots allocated to each node will also be different. As the network scale increases, the available bandwidth will become more limited, and the packet transmission rate of the simulation object will be affected. In the simulation network, the subnet setting between node 1 and node 2 adopts CSMA mode. Fig.10 The figure shows the change of data transmission rate as the network scale increases. It can be seen that when there are only two nodes in the network, the bandwidth resources of the network can support the frequency of message sending. Therefore, the data transmission rates of the traditional scheme and this scheme are very high. When the network scale gradually increases, the average time slot resources allocated to each node in the traditional scheme are small and cannot support the frequency of sending service packets, so the data transmission rate will drop rapidly. In this scheme, since the application end can perceive the changes in network resources and transmission requirements, and control the frequency of sending data packets according to service requirements, the amount of data packets in network transmission is less than the idle bandwidth resources of the network, so the success rate of data packet transmission will not be greatly affected.

[0103] In the simulated network topology, according to the actual performance of the relevant transmission equipment, the subnet delay between node 1 and node 2 is set to 100ms, the subnet delay between node 2 and node 3 is set to 200ms, the subnet delay between node 3 and node 4 is set to 200ms, and the delay between node 4 and satellite node 1 is set to 100ms. Data packets are sent from node 1 to satellite node 1 at transmission intervals of 100ms, 200ms, 300ms, 400ms, etc. The simulation results are shown in Figure 2. Fig.10 shown.

[0104] from Fig.11 From the simulation results, it can be seen that the sender cannot send packets reasonably according to service requirements because the traditional solution cannot perceive the global view of the network topology and cannot control the flow of available network resources before sending packets. However, the resources of each subnet in the network are limited. When the network resources cannot support the transmission requirements of the service, the only way to transmit packets is to rely on the queuing strategy of each node in the network. When the traffic exceeds the available bandwidth resources of the subnet, the transmission of other services will be affected and the entire network will be paralyzed. This solution first perceives the network resources, controls the flow from the service source, and controls the sending of service packets through the available resources of the network, so that the network performance is not affected, the success rate of service transmission is improved, and the reliability of service transmission is enhanced.

[0105] Satellite time is used as the seed parameter for generating secret keys during message transmission. Messages are encrypted before sending and decrypted when received. The process of generating keys, encryption, and decryption will introduce certain processing delays. However, compared with wireless communication networks, the processing delays in scenarios with higher delays are usually smaller. To verify the impact of encryption and decryption delays on the system, this scheme sets the delay between node 2 and node 3 to 300ms and the MTU to 1500 bytes; the delay between node 1 and node 2 and between node 4 and satellite node 1 to 800ms and the MTU to 512 bytes. Each subnet uses the CSMA mode, and the simulation results are shown in the figure. Fig.12 As shown. Fig.12 It can be seen from the simulation results that under different message length transmission conditions, there is no significant difference between the method of the present application and the traditional solution. Therefore, in the wireless communication scenario, the delay caused by encryption processing has a negligible impact on the transmission performance of the entire communication system.

[0106] The link transmission delay between node 1 and satellite node 1 is set to 500ms, each subnet adopts CSMA mode, the average link packet loss rate is set to 5%, the MTU value is set to 128 bytes, 256 bytes, 384 bytes and 512 bytes respectively, and 1500 bytes of data are transmitted. The simulation test results of the traditional scheme and this scheme are compared. Fig.13As shown. Under different MTU values, both the traditional scheme and this scheme need to be fragmented according to different MTU values. However, in the traditional scheme, when a data packet is lost during transmission, the entire data packet needs to be retransmitted, which may cause data packet blocking due to network congestion, increase delay, and even disorder. In contrast, this scheme fragments network resources based on the resource-aware protocol, which can reduce the risk of network congestion. For lost fragments, only retransmission is required. Since the message carries the satellite timestamp, the message fragmentation and reassembly process is more accurate and will not cause disorder. The simulation results show that when different MTU values ​​are set, the transmission delay of this scheme is significantly lower than the transmission delay of the traditional scheme.

[0107] In summary, the data transmission method and system based on satellite time synchronization and dynamic time slot allocation proposed in this application optimizes the communication network as a whole based on the application layer business requirements, proposes a safe and reliable transmission scheme based on satellite time synchronization and dynamic time slot allocation, and designs a wireless communication scheme, resource-aware protocol and information processing mechanism based on the scheme. Without changing the structure of the network itself, the reliability of communication network transmission is effectively improved by combining the resource-aware protocol and the information processing mechanism.

[0108] Especially from the perspective of the business field, the present invention can dynamically adjust the communication mode according to user needs, reduce the dependence on the existing topology of the communication network, and effectively improve the efficiency of data transmission. The collection of global network resources is realized through resource perception, and on-demand transmission is performed based on network slicing. During the data transmission process, the packet loss and retransmission mechanism can be dynamically adjusted to better adapt to various complex communication scenarios and ensure reliable data transmission in various complex battlefield environments.

[0109] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by any technician familiar with the technical field within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention.

Claims

1. A data transmission method based on satellite time synchronization and dynamic time slot allocation, characterized in that: include: The terminal side sends detection messages to multiple subnet nodes in the network at the application layer; After receiving the detection message, each subnet node reports dynamic information according to the current node status; The terminal side performs message fragmentation and time slot division at the application layer according to the reporting information of each node, formulates a data packet transmission strategy, and performs data transmission based on the data packet transmission strategy.

2. The data transmission method based on satellite time synchronization and dynamic time slot allocation according to claim 1, characterized in that: The terminal-side application layer and the subnet node communicate via a preset resource awareness protocol; The detection message of the preset resource awareness protocol includes a first message type sent from a source end node to a destination end node, and a second message type sent from the destination end node to a source node; Each node updates the relevant fields in the detection message according to the resource information collected during the subnet networking; The resource information includes the satellite synchronization time of each node, the bandwidth resources of each subnet, the number of nodes of each subnet and the MTU value of each node.

3. The data transmission method based on satellite time synchronization and dynamic time slot allocation according to claim 2, characterized in that: Each node updates the relevant fields in the detection message according to the resource information collected during subnet networking, including: When the detection message is of the first message type, the source end node sends an initial detection message to a first relay node on a path to the destination end node; The first relay node updates the initial detection message, obtains the minimum value of each resource information, and searches for a feasible path to select an outbound interface to forward the updated detection message to the next relay node; Each relay node updates the resource field in the acquired detection message according to the resource information collected during networking, and updates the minimum value of each resource information until the detection message is sent to the destination node.

4. The data transmission method based on satellite time synchronization and dynamic time slot allocation according to claim 2, characterized in that: The structure of the detection message includes satellite time, data header and valid data; The satellite time is used for time synchronization and also for generating the seed parameters of the key to encrypt the data header and valid data of the message; During the data transmission process, the data header and valid data are transmitted in an encrypted manner, and the satellite time is transmitted in an unencrypted manner.

5. The data transmission method based on satellite time synchronization and dynamic time slot allocation according to claim 1, characterized in that: The working status of the terminal side application layer in data interaction includes: Decryption state, in the state of receiving and decrypting the message to be sent; The data packet processing state is in the state of determining whether the message needs to be fragmented and checking whether the data is wrong; The message sending status indicates that when the data check result is correct, the message is fragmented according to the MTU value, and data is sent after the sent time slot arrives. The message sending is completed after the feedback information is received.

6. The data transmission method based on satellite time synchronization and dynamic time slot allocation according to claim 1, characterized in that: The terminal side performs message fragmentation and time slot division at the application layer based on the reported information of each node, including: The message is fragmented based on the minimum MTU value of the current subnet node, so that the size of each message slice does not exceed the minimum MTU value of the subnet node; The calculation formula for the optimal time slot length of each node in the subnet is: Among them, T best represents the optimal time slot length of each node, M min Indicates the minimum MTU value of the current subnet node, R c Indicates the current number of network resources of each node.

7. The data transmission method based on satellite time synchronization and dynamic time slot allocation according to claim 6, characterized in that: The terminal side formulates a data packet transmission strategy at the application layer based on the reported information of each node, including: Allocate time slots based on the effective bandwidth resources of the current subnet, so that the number of effective resources of each node is less than the minimum network resources available in the current subnet node; The calculation formula for the number of effective resources of each node is: Among them, R v <R min , R min Indicates the number of effective resources of each node on the minimum network resources available in the current subnet node, R v Indicates the number of effective resources of each node, T best represents the optimal time slot length of each node, M min Indicates the minimum MTU value of the current subnet node, T c Indicates the current time slot length of each node.

8. The data transmission method based on satellite time synchronization and dynamic time slot allocation according to claim 1, characterized in that: Transmitting data based on the data packet transmission strategy includes: Acquire and store a time slot allocation table containing multiple nodes, traverse the time slot allocation table, and fill in the current satellite time as the sending time in the idle time slot; When response data is received, the current data cache is traversed to determine whether there is a timestamp equal to the timestamp in the received response message header; if so, it is confirmed that the received message is an acknowledgment of the sent message and the current data cache resources are released; if the current message is a message to be sent and there is no available sending time slot, the message is stored in the queue and waits for the next available time slot to be sent again.

9. A data transmission system based on satellite time synchronization and dynamic time slot allocation, characterized in that: It comprises a plurality of communication terminals, which are connected by a plurality of subnets of different types; each communication terminal is deployed with a service processing module at the application layer; the service processing module adopts the data transmission based on satellite time synchronization and dynamic time slot allocation as described in any one of claims 1 to 8 for data communication.

10. The data transmission system based on satellite time synchronization and dynamic time slot allocation according to claim 9, characterized in that: The types of the subnet include at least non-IP network, full IP network and single-soldier network.

Images