Device-free cross-region dynamic time synchronization method based on sensor network

Abstract

The invention provides a device-free cross-region dynamic time synchronization method based on a sensor network, which relates to the technical field of time synchronization, and comprises the following steps: constructing a network security communication model according to a network topological graph and communication parameter conditions of a network security region set; based on the network security communication model, acquiring communication delay measurement data of a communication E file and node position information corresponding to the network security area set; based on a time deviation determination strategy, calculating a target time deviation corresponding to the network security area set according to the communication delay measurement data and the node position information; performing time synchronization processing on the network security area set based on the target time deviation; and verifying a time synchronization result corresponding to the network security area set, and adjusting and optimizing the time deviation determination strategy according to the verification result, thereby realizing high-precision and low-cost time synchronization without an additional time synchronization device by using communication delay and measurement information between network security area nodes.

Description

Technical Field

[0001] The present invention relates to the technical field of time synchronization, and in particular to a device-free cross-region dynamic time synchronization method based on a sensor network. Background Art

[0002] In sensor networks, time synchronization directly affects the efficiency and accuracy of data fusion, event detection, positioning, and network collaboration.

[0003] In the prior art, traditional time synchronization methods often need to rely on additional time synchronization devices, such as GPS receivers or network time protocol servers, which not only increase the complexity and cost of time synchronization operations, but also may not operate normally in certain specific environments, such as indoors, underground or deep in the sea. In addition, due to the wide geographical distribution of cross-regional sensor networks, communication delays and packet loss are more serious, and traditional static time synchronization methods are difficult to adapt to this dynamically changing network environment.

[0004] Therefore, it is necessary to provide a device-free cross-region dynamic time synchronization method based on a sensor network to solve the above technical problems. Summary of the invention

[0005] In order to solve the above technical problems, the present invention provides a device-free cross-region dynamic time synchronization method based on a sensor network, which is used to solve the problems that traditional time synchronization methods rely on additional time synchronization devices, increase the complexity and cost of time synchronization operations, and are prone to device operation failures, and the existing static time synchronization methods are difficult to adapt to the dynamically changing cross-regional sensor network environment.

[0006] The present invention provides a device-free cross-region dynamic time synchronization method based on a sensor network, comprising: According to the network topology diagram and communication parameter conditions of the network security zone set, a network security communication model is constructed; Based on the network security communication model, obtaining communication delay measurement data of the communication E file and node location information corresponding to the network security zone set; Based on the time deviation determination strategy, a target time deviation corresponding to the network security zone set is calculated according to the communication delay measurement data and the node location information; Performing time synchronization processing on the network security zone set based on the target time deviation; Verify the time synchronization result corresponding to the network security zone set, and adjust and optimize the time deviation determination strategy according to the verification result.

[0007] Preferably, the constructing of a network security communication model according to the network topology diagram and communication parameter conditions of the network security zone set specifically includes: The network security zone set includes a sending network security zone node and a receiving network security zone node, the network security zone node is used to send the communication E file, and the receiving network security zone node is used to receive the communication E file; Identify the sending node location information corresponding to the sending network security zone node, the receiving node location information corresponding to the receiving network security zone node, and the node connection relationship between the network security zone node and the receiving network security zone node; Determine the transmission signal range and transmission signal strength of the communication E file according to the sending node position information, the receiving node position information and the node connection relationship, and determine the real-time communication link between the sending network security zone node and the receiving network security zone node based on the transmission signal range and transmission signal strength; Performing a quality assessment on the real-time communication link and constructing a network security topology map according to the assessment result; A network security communication protocol is selected, and communication parameter conditions corresponding to the sending network security zone node and the receiving network security zone node are obtained. Based on the network security communication protocol, the network security communication model is constructed according to the network security topology diagram and the communication parameter conditions.

[0008] Preferably, the calculation formula for the transmission signal strength of the communication E file is as follows: In the formula, Indicates the receiving power of the communication E file received by the node in the receiving network security zone, that is, the transmission signal strength of the communication E file; Indicates the sending power of the E-file of the sending network security zone node; The sending gain of the E-file of the sending communication of the node in the sending network security zone; Indicates the receiving gain of the node in the receiving network security zone for receiving the communication E file; It represents the transmission signal wavelength of the communication E file; d represents the distance between the node in the sending network security zone and the node in the receiving network security zone.

[0009] Preferably, when performing quality assessment on the real-time communication link, the calculation formula of the path loss of the real-time communication link is as follows: Where L represents the path loss of the real-time communication link; Indicates the reference distance The path loss at the node is n, the path loss exponent is n, and d is the distance between the node in the sending network security zone and the node in the receiving network security zone.

[0010] Preferably, obtaining the communication delay measurement data of the communication E file based on the network security communication model specifically includes: Based on the network security communication model, the sending network security zone node sends the communication E file to the receiving network security zone node by penetrating the isolation device, and the communication E file includes the file sending time T1 and the sending sequence number; After receiving the communication E file, the receiving network security zone node determines the first file receiving time T2; Calculate the communication delay time D based on the file sending time T1 and the first file receiving time T2, and add the first file receiving time T2 to the communication E file to obtain the updated communication E file; Feedback the updated communication E file and communication delay time D to the sending network security zone node; After receiving the updated communication E file and the communication delay time D, the sending network security zone node determines the second file receiving time T3; The communication round-trip time T is calculated based on the file sending time T1 and the second file receiving time T3. WF =T3-T1; Based on the communication round trip time T WF Calculate the one-way communication delay time by adding the communication delay time D ; According to the one-way communication delay time T YC The communication delay measurement data is obtained.

[0011] Preferably, the time deviation-based determination strategy calculates the target time deviation corresponding to the network security zone set according to the communication delay measurement data and the node location information, specifically including: Preprocessing the communication delay measurement data and node location information; The preprocessed communication delay measurement data and node position information are used as control inputs, and the state estimation of the target time deviation is performed based on the time deviation determination strategy. The expression of the state estimation of the target time deviation at the current moment is predicted as follows: In the formula, represents the state estimate of the current time k of the target time deviation; A represents the state transfer matrix; represents the state estimation of the previous moment k-1 of the target time deviation; B represents the control input matrix; represents the control input at the previous time k-1 of the target time deviation; The expression of the covariance matrix of the predicted state of the target time deviation at the current moment is as follows: In the formula, represents the covariance matrix of the predicted state at the current time k of the target time deviation; A represents the state transfer matrix; The covariance matrix representing the state of the previous moment k-1 of the target time deviation; represents the transpose of the state transfer matrix; Q represents the covariance matrix of the process noise.

[0012] Preferably, the expression of the Kalman gain of the target time deviation at the current moment is as follows: In the formula, The Kalman gain at the current time k representing the target time deviation; represents the covariance matrix of the predicted state at the current time k of the target time deviation; H represents the observation matrix; represents the transpose of the observation matrix; R represents the covariance matrix of the observation noise.

[0013] Preferably, the expression of the updated state estimation of the target time deviation at the current moment is as follows: In the formula, represents the state estimate at the current time k of the updated target time deviation; The Kalman gain at the current time k representing the target time deviation; represents the observed value of the current time k of the target time deviation; H represents the observation matrix; The state estimate at the current time k representing the target time deviation; The expression of the covariance matrix of the predicted state of the updated target time deviation at the current moment is as follows: In the formula, The covariance matrix representing the predicted state at the current time k of the updated target time deviation; represents the Kalman gain of the current time k of the target time deviation; H represents the observation matrix; The covariance matrix of the predicted state at the current time k representing the target time deviation; When the state estimate and the covariance matrix reach a preset maximum update number, the current best estimate of the target time deviation is output.

[0014] Compared with the related art, the device-free cross-region dynamic time synchronization method based on sensor network provided by the present invention has the following beneficial effects: The present invention can construct a network security communication model according to a network topology diagram and communication parameter conditions of a network security zone set; obtain communication delay measurement data of a communication E file and node location information corresponding to the network security zone set; based on a time deviation determination strategy, calculate a target time deviation corresponding to the network security zone set according to the communication delay measurement data and the node location information; perform time synchronization processing on the network security zone set based on the target time deviation; verify the time synchronization result corresponding to the network security zone set, and adjust and optimize the time deviation determination strategy according to the verification result, so that the communication delay and measurement information between network security zone nodes can be used to achieve high-precision, low-cost time synchronization without the need for additional time synchronization devices.

[0015] The present invention does not require additional timing devices, and can reduce the complexity and cost of time synchronization operations; the present invention can adapt to topology changes and deteriorating communication conditions in cross-regional sensor networks and maintain the accuracy of time synchronization; the present invention can achieve high-precision time synchronization through accurate communication delay measurement and time deviation calculation; the method of the present invention can be applied to different types of sensor networks, is not constrained by deployment scenarios and is not affected by the number of servers or isolation devices, has comprehensive data coverage, and has good scalability. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 A flow chart of a device-free cross-region dynamic time synchronization method based on a sensor network according to the present invention; Figure 2 A schematic diagram of the communication E file transmission of the present invention; Figure 3 It is a schematic diagram of the node synchronization interaction of the present invention. DETAILED DESCRIPTION

[0017] The present invention will be further described below in conjunction with the accompanying drawings and implementation modes.

[0018] like Figure 1 As shown, a device-free cross-region dynamic time synchronization method based on a sensor network includes: S1, constructing a network security communication model based on the network topology diagram and communication parameter conditions of the network security zone set; S2, based on the network security communication model, obtaining communication delay measurement data of the communication E file and node location information corresponding to the network security zone set; S3, based on the time deviation determination strategy, calculating the target time deviation corresponding to the network security zone set according to the communication delay measurement data and the node location information; S4, performing time synchronization processing on the network security zone set based on the target time deviation; S5, verifying the time synchronization result corresponding to the network security zone set, and adjusting and optimizing the time deviation determination strategy according to the verification result.

[0019] Among them, firstly, a network security communication model corresponding to the network security zone set can be constructed according to the network topology diagram and communication parameter conditions, so as to ensure the confidentiality, integrity and availability of the transmission process of the communication E file.

[0020] Furthermore, the communication delay measurement data of the communication E file can be collected, that is, the time delay experienced by the communication E file from the sending network security zone node to the receiving network security zone node, which is an important indicator for measuring network communication performance. At the same time, the geographical location information of the sending network security zone node and the receiving network security zone node in the network security zone set can be obtained, including latitude and longitude coordinates, network access points and other parameters.

[0021] Next, the time deviation determination strategy can be used to accurately calculate the target time deviation between the sending network security zone node and the receiving network security zone node based on the communication delay measurement data and node location information.

[0022] Based on the calculated target time deviation, time synchronization processing technology can be used to adjust the local clock of each node to make it highly consistent with the reference clock, thereby eliminating communication timing errors caused by clock asynchrony, thereby maintaining the temporal sequence of network events and ensuring the consistency and coordination of time synchronization processing.

[0023] After the time synchronization process is completed, the time synchronization results of the network security zone set can be verified, including using the NTP server to compare the benchmark time, monitoring the time drift rate, and evaluating the impact of the time synchronization process on business continuity. Based on the verification results, the time deviation determination strategy can be adjusted and optimized, such as adjusting algorithm parameters, introducing synchronization mechanisms, or enhancing the robustness of network infrastructure, so as to ensure that the network security communication model can continue to operate effectively in a complex and changing network environment.

[0024] Through the above method, accurate time synchronization processing can be achieved to provide stable and efficient communication guarantee for network security zone collection.

[0025] In the specific implementation process, the network topology diagram and communication parameter conditions of the network security zone set are used to construct a network security communication model, which specifically includes: The network security zone set includes a sending network security zone node and a receiving network security zone node, the network security zone node is used to send the communication E file, and the receiving network security zone node is used to receive the communication E file; Identify the sending node location information corresponding to the sending network security zone node, the receiving node location information corresponding to the receiving network security zone node, and the node connection relationship between the network security zone node and the receiving network security zone node; Determine the transmission signal range and transmission signal strength of the communication E file according to the sending node position information, the receiving node position information and the node connection relationship, and determine the real-time communication link between the sending network security zone node and the receiving network security zone node based on the transmission signal range and transmission signal strength; Performing a quality assessment on the real-time communication link and constructing a network security topology map according to the assessment result; A network security communication protocol is selected, and communication parameter conditions corresponding to the sending network security zone node and the receiving network security zone node are obtained. Based on the network security communication protocol, the network security communication model is constructed according to the network security topology diagram and the communication parameter conditions.

[0026] like Figure 2 As shown, the network security zone set is composed of a sending network security zone node and a receiving network security zone node. The sending network security zone node can send communication E files, and the receiving network security zone node can receive and store these communication E files.

[0027] It is understood that first, the location information of the sending network security zone node and the receiving network security zone node can be identified and recorded, including their physical or logical positioning in the network architecture. At the same time, the node connection relationship between the two can be determined, including the routing path of direct connection or indirect connection via an intermediate node.

[0028] Furthermore, based on the above-mentioned node location information and connection relationship, the signal propagation model can be used to calculate the transmission signal range and strength of the communication E file, and predict the signal attenuation of the communication E file under different conditions, thereby determining the real-time communication link between the sending network security zone node and the receiving network security zone node, ensuring the stability and reliability of the communication E file during the transmission process.

[0029] In order to ensure the quality of real-time communication links, a comprehensive quality assessment can be performed, including monitoring and analysis of key performance indicators such as bit error rate, latency, jitter, etc. Based on these assessment results, the network configuration can be dynamically adjusted, the transmission path can be optimized, and a high-quality network security topology map reflecting the current network status can be generated.

[0030] In the process of building a network security communication model, we can deeply analyze the characteristics of various network security communication protocols, such as IPSec, TLS, etc., and select specific network security communication protocols based on the security needs, performance requirements and compatibility of actual application scenarios.

[0031] Then, the communication parameter conditions corresponding to the sending network security zone node and the receiving network security zone node can be obtained, including encryption keys, authentication mechanisms, and data integrity checks.

[0032] Finally, based on the selected network security communication protocol, the network security topology diagram and communication parameter conditions can be used to build a network security communication model. This model can effectively ensure the transmission security of communication E files, and can be adaptively adjusted according to changes in the network environment to ensure the continuous stability and efficient operation of the communication link.

[0033] The calculation formula of the transmission signal strength of the communication E file is as follows: In the formula, Indicates the receiving power of the communication E file received by the node in the receiving network security zone, that is, the transmission signal strength of the communication E file; Indicates the sending power of the E-file of the sending network security zone node; The sending gain of the E-file of the sending communication of the node in the sending network security zone; Indicates the receiving gain of the node in the receiving network security zone for receiving the communication E file; It represents the transmission signal wavelength of the communication E file; d represents the distance between the node in the sending network security zone and the node in the receiving network security zone.

[0034] It is understandable that in this formula, It represents the receiving power of the node in the receiving network security zone when receiving the communication E file, that is, the transmission signal strength of the communication E file. Next, the sending power of the node in the sending network security zone when sending the communication E file can be obtained.

[0035] In addition, the sending gain refers to the signal gain of the node in the sending network security zone when transmitting the communication E file. The receiving gain refers to the signal gain of the node in the receiving network security zone when receiving the communication E file. By introducing the transmission signal wavelength of the communication E file and the actual distance between the node in the sending network security zone and the node in the receiving network security zone, the transmission signal strength of the communication E file can be calculated.

[0036] When performing quality assessment on the real-time communication link, the calculation formula of the path loss of the real-time communication link is as follows: Where L represents the path loss of the real-time communication link; Indicates the reference distance The path loss at the node is n, the path loss exponent is n, and d is the distance between the node in the sending network security zone and the node in the receiving network security zone.

[0037] It should be noted that in the quality evaluation process of the real-time communication link, the path loss of the real-time communication link needs to be accurately calculated. Specifically, L represents the path loss of the real-time communication link, which measures the energy attenuation of the signal due to the increase in distance during the transmission process; Indicates the preset reference distance =Path loss at the location; n represents the path loss index, which reflects the rate at which the signal attenuates with distance; d represents the straight-line distance between the node in the sending network security zone and the node in the receiving network security zone. By combining these parameters, the quality of the real-time communication link can be effectively evaluated and corresponding optimization measures can be taken.

[0038] The obtaining, based on the network security communication model, the communication delay measurement data of the communication E file specifically includes: Based on the network security communication model, the sending network security zone node sends the communication E file to the receiving network security zone node by penetrating the isolation device, and the communication E file includes the file sending time T1 and the sending sequence number; After receiving the communication E file, the receiving network security zone node determines the first file receiving time T2; Calculate the communication delay time D based on the file sending time T1 and the first file receiving time T2, and add the first file receiving time T2 to the communication E file to obtain the updated communication E file; Feedback the updated communication E file and communication delay time D to the sending network security zone node; After receiving the updated communication E file and the communication delay time D, the sending network security zone node determines the second file receiving time T3; The communication round-trip time T is calculated based on the file sending time T1 and the second file receiving time T3. WF =T3-T1; Based on the communication round trip time T WF Calculate the one-way communication delay time by adding the communication delay time D ; According to the one-way communication delay time T YC The communication delay measurement data is obtained.

[0039] Among them, based on the network security communication model, the sending network security zone node is used to send the communication E file, which is embedded with key timestamp information, namely the file sending time T1 and the sending sequence number used for verification and sorting. In order to ensure the secure transmission of data, the sending network security zone node can send the communication E file to the receiving network security zone node by penetrating the isolation device.

[0040] Once the receiving network security zone node successfully captures the communication E file, it can immediately record the first file receiving time T2. Through accurate timestamp comparison, that is, the difference between the file sending time T1 and the first file receiving time T2, the communication delay time D can be obtained. Then, the receiving network security zone node can add the first file receiving time T2 to the communication E file to obtain an updated communication E file.

[0041] Furthermore, the updated communication file E and the communication delay time D can be fed back to the node in the sending network security zone, thereby ensuring the bidirectional flow of data and providing the node in the sending network security zone with information to verify the communication delay. After receiving this information, the node in the sending network security zone can immediately record the second file receiving time T3, and then calculate the communication round trip time T WF , the corresponding calculation formula is: T WF =T3-T1.

[0042] After obtaining the communication round trip time T WF After that, the one-way communication delay time T can be further calculated by combining the communication delay time D YC Among them, the one-way communication delay time can accurately reflect the quality and efficiency of the communication link. Finally, based on the one-way communication delay time, the required communication delay measurement data can be obtained.

[0043] For example, Figure 3 As shown, the sending network security zone node is security zone 2, which can send communication E file. The file content is the file sending time and sending sequence number. After penetrating the isolation device, the communication E file can reach the receiving network security zone node, that is, security zone 3. After receiving the communication E file, the security zone 3 server can parse it and add the time of receiving the file at the end of the file content, which is the first file receiving time.

[0044] Furthermore, after receiving the communication E file, the second security zone can analyze it. The specific steps are as follows: before sending the communication E file, the sending network security zone node records the current time; sends the serial number and the current sending time together to the receiving network security zone node; after receiving the communication E file, the receiving network security zone node records the current time; calculates the transmission delay from the sending network security zone node to the receiving network security zone node; operates again; sends the calculated delay back to the sending network security zone node; calculates the round-trip time; after receiving the delay, records the current time; calculates the round-trip time; uses the round-trip time and delay to calculate the one-way delay to obtain the communication delay measurement data.

[0045] The time deviation-based determination strategy, calculating the target time deviation corresponding to the network security zone set according to the communication delay measurement data and the node location information, specifically includes: Preprocessing the communication delay measurement data and node location information; The preprocessed communication delay measurement data and node position information are used as control inputs, and the state estimation of the target time deviation is performed based on the time deviation determination strategy. The expression of the state estimation of the target time deviation at the current moment is predicted as follows: In the formula, represents the state estimate of the current time k of the target time deviation; A represents the state transfer matrix; represents the state estimation of the previous moment k-1 of the target time deviation; B represents the control input matrix; represents the control input at the previous time k-1 of the target time deviation; The expression of the covariance matrix of the predicted state of the target time deviation at the current moment is as follows: In the formula, represents the covariance matrix of the predicted state at the current time k of the target time deviation; A represents the state transfer matrix; The covariance matrix representing the state of the previous moment k-1 of the target time deviation; represents the transpose of the state transfer matrix; Q represents the covariance matrix of the process noise.

[0046] The expression of the Kalman gain of the target time deviation at the current moment is as follows: In the formula, The Kalman gain at the current time k representing the target time deviation; represents the covariance matrix of the predicted state at the current time k of the target time deviation; H represents the observation matrix; represents the transpose of the observation matrix; R represents the covariance matrix of the observation noise.

[0047] The expression of the updated state estimation of the target time deviation at the current moment is as follows: In the formula, represents the state estimate at the current time k of the updated target time deviation; The Kalman gain at the current time k representing the target time deviation; represents the observed value of the current time k of the target time deviation; H represents the observation matrix; The state estimate at the current time k representing the target time deviation; The expression of the covariance matrix of the predicted state of the updated target time deviation at the current moment is as follows: In the formula, The covariance matrix representing the predicted state at the current time k of the updated target time deviation; represents the Kalman gain of the current time k of the target time deviation; H represents the observation matrix; The covariance matrix of the predicted state at the current time k representing the target time deviation; When the state estimate and the covariance matrix reach a preset maximum update number, the current best estimate of the target time deviation is output.

[0048] In practical applications, the collected communication delay measurement data and node location information can first be preprocessed, including data cleaning, formatting, and elimination of outliers, so as to ensure the accuracy and reliability of the data.

[0049] Furthermore, the preprocessed communication delay measurement data and node location information can be used as control inputs, and the time deviation determination strategy can be used to perform state estimation on the target time deviation. The state estimation of the target time deviation at the current moment is predicted, which comprehensively considers multiple factors such as the state transfer matrix, the state estimation at the previous moment, and the control input matrix, thereby achieving dynamic tracking and accurate prediction of the target time deviation.

[0050] At the same time, in order to evaluate the accuracy of the prediction results, the covariance matrix of the predicted state at the current moment of the target time deviation can be calculated. This matrix can reflect the uncertainty of the predicted state, which comprehensively considers multiple variables such as the state transfer matrix, the state covariance matrix of the previous moment, and the covariance matrix of the process noise.

[0051] After obtaining the predicted state and covariance matrix, the Kalman filter algorithm can be further used to update the target time deviation. The calculation of the Kalman gain combines the covariance matrix of the predicted state, the observation matrix, and the covariance matrix of the observation noise, realizing the effective use of the observation information. Through the Kalman gain, the state estimate of the target time deviation at the current moment can be corrected to obtain the updated state estimate.

[0052] In addition, the covariance matrix of the predicted state at the current moment of the target time deviation can be updated to reflect the uncertainty of the updated state estimate. The update process comprehensively considers multiple factors such as the Kalman gain, the observation matrix, and the covariance matrix of the predicted state.

[0053] Finally, when the state estimate and covariance matrix reach the preset maximum number of updates, the current best estimate of the target time deviation can be output. This result can reflect the time synchronization status of the network security zone set, which is helpful for subsequent network optimization and troubleshooting.

[0054] Through the introduction of the above embodiments, the present invention can build a network security communication model according to the network topology diagram and communication parameter conditions of the network security zone set through a device-free cross-zone dynamic time synchronization method based on a sensor network; obtain the communication delay measurement data of the communication E file and the node location information corresponding to the network security zone set; based on the time deviation determination strategy, calculate the target time deviation corresponding to the network security zone set according to the communication delay measurement data and the node location information; perform time synchronization processing on the network security zone set based on the target time deviation; verify the time synchronization result corresponding to the network security zone set, and adjust and optimize the time deviation determination strategy according to the verification result, so that the communication delay and measurement information between the network security zone nodes can be used to achieve high-precision, low-cost time synchronization without the need for additional timing devices.

[0055] The present invention does not require additional timing devices, and can reduce the complexity and cost of time synchronization operations; the present invention can adapt to topology changes and deteriorating communication conditions in cross-regional sensor networks and maintain the accuracy of time synchronization; the present invention can achieve high-precision time synchronization through accurate communication delay measurement and time deviation calculation; the method of the present invention can be applied to different types of sensor networks, is not constrained by deployment scenarios and is not affected by the number of servers or isolation devices, has comprehensive data coverage, and has good scalability.

[0056] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0057] Those skilled in the art can understand that all or part of the steps in the various methods of the above embodiments can be completed by instructing related hardware through a program, and the program can be stored in a computer-readable storage medium, and the storage medium includes a read-only memory (ROM), a random access memory (RAM), a programmable read-only memory (PROM), an erasable programmable read-only memory (EPROM), a one-time programmable read-only memory (OTPROM), an electronically erasable rewritable read-only memory (EEPROM), a compact disc (CD-ROM) or other optical disc storage, magnetic disk storage, magnetic tape storage, or any other computer-readable medium that can be used to carry or store data.

[0058] It should also be noted that the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, commodity or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, commodity or device. In the absence of more restrictions, the elements defined by the sentence "comprises a ..." do not exclude the existence of other identical elements in the process, method, commodity or device including the elements.

Claims

1. A device-free cross-region dynamic time synchronization method based on a sensor network, characterized in that: include: According to the network topology diagram and communication parameter conditions of the network security zone set, a network security communication model is constructed; Based on the network security communication model, obtaining communication delay measurement data of the communication E file and node location information corresponding to the network security zone set; Based on the time deviation determination strategy, a target time deviation corresponding to the network security zone set is calculated according to the communication delay measurement data and the node location information; Performing time synchronization processing on the network security zone set based on the target time deviation; Verify the time synchronization result corresponding to the network security zone set, and adjust and optimize the time deviation determination strategy according to the verification result.

2. According to the sensor network-based device-free cross-region dynamic time synchronization method of claim 1, it is characterized in that: The constructing of a network security communication model according to the network topology diagram and communication parameter conditions of the network security zone set specifically includes: The network security zone set includes a sending network security zone node and a receiving network security zone node, the network security zone node is used to send the communication E file, and the receiving network security zone node is used to receive the communication E file; Identify the sending node location information corresponding to the sending network security zone node, the receiving node location information corresponding to the receiving network security zone node, and the node connection relationship between the network security zone node and the receiving network security zone node; Determine the transmission signal range and transmission signal strength of the communication E file according to the sending node position information, the receiving node position information and the node connection relationship, and determine the real-time communication link between the sending network security zone node and the receiving network security zone node based on the transmission signal range and transmission signal strength; Performing a quality assessment on the real-time communication link and constructing a network security topology map according to the assessment result; A network security communication protocol is selected, and communication parameter conditions corresponding to the sending network security zone node and the receiving network security zone node are obtained. Based on the network security communication protocol, the network security communication model is constructed according to the network security topology diagram and the communication parameter conditions.

3. According to claim 2, a device-free cross-region dynamic time synchronization method based on a sensor network is characterized in that: The calculation formula of the transmission signal strength of the communication E file is as follows: In the formula, Indicates the receiving power of the communication E file received by the node in the receiving network security zone, that is, the transmission signal strength of the communication E file; Indicates the sending power of the E-file of the sending network security zone node; The sending gain of the E-file of the sending communication of the node in the sending network security zone; Indicates the receiving gain of the node in the receiving network security zone for receiving the communication E file; It represents the transmission signal wavelength of the communication E file; d represents the distance between the node in the sending network security zone and the node in the receiving network security zone.

4. According to claim 2, a device-free cross-region dynamic time synchronization method based on a sensor network is characterized in that: When performing quality assessment on the real-time communication link, the calculation formula of the path loss of the real-time communication link is as follows: Where L represents the path loss of the real-time communication link; Indicates the reference distance The path loss at the node is n, the path loss exponent is n, and d is the distance between the node in the sending network security zone and the node in the receiving network security zone.

5. According to the sensor network-based device-free cross-region dynamic time synchronization method of claim 1, it is characterized in that: The obtaining, based on the network security communication model, the communication delay measurement data of the communication E file specifically includes: Based on the network security communication model, the sending network security zone node sends the communication E file to the receiving network security zone node by penetrating the isolation device, and the communication E file includes the file sending time T1 and the sending sequence number; After receiving the communication E file, the receiving network security zone node determines the first file receiving time T2; Calculate the communication delay time D based on the file sending time T1 and the first file receiving time T2, and add the first file receiving time T2 to the communication E file to obtain the updated communication E file; Feedback the updated communication E file and communication delay time D to the sending network security zone node; After receiving the updated communication E file and the communication delay time D, the sending network security zone node determines the second file receiving time T3; The communication round-trip time T is calculated based on the file sending time T1 and the second file receiving time T3. WF =T3-T1; Based on the communication round trip time T WF Calculate the one-way communication delay time by adding the communication delay time D ; According to the one-way communication delay time T YC The communication delay measurement data is obtained.

6. The method for device-free cross-region dynamic time synchronization based on sensor network according to claim 1, characterized in that: The time deviation-based determination strategy, calculating the target time deviation corresponding to the network security zone set according to the communication delay measurement data and the node location information, specifically includes: Preprocessing the communication delay measurement data and node location information; The preprocessed communication delay measurement data and node position information are used as control inputs, and the state estimation of the target time deviation is performed based on the time deviation determination strategy. The expression of the state estimation of the target time deviation at the current moment is predicted as follows: In the formula, represents the state estimate of the current time k of the target time deviation; A represents the state transfer matrix; represents the state estimation of the previous moment k-1 of the target time deviation; B represents the control input matrix; represents the control input at the previous time k-1 of the target time deviation; The expression of the covariance matrix of the predicted state of the target time deviation at the current moment is as follows: In the formula, represents the covariance matrix of the predicted state at the current time k of the target time deviation; A represents the state transfer matrix; The covariance matrix representing the state of the previous moment k-1 of the target time deviation; represents the transpose of the state transfer matrix; Q represents the covariance matrix of the process noise.

7. A device-free cross-region dynamic time synchronization method based on a sensor network according to claim 6, characterized in that: The expression of the Kalman gain of the target time deviation at the current moment is as follows: In the formula, The Kalman gain at the current time k representing the target time deviation; represents the covariance matrix of the predicted state at the current time k of the target time deviation; H represents the observation matrix; represents the transpose of the observation matrix; R represents the covariance matrix of the observation noise.

8. The method for device-free cross-region dynamic time synchronization based on sensor network according to claim 7, characterized in that: The expression of the updated state estimation of the target time deviation at the current moment is as follows: In the formula, represents the state estimate at the current time k of the updated target time deviation; The Kalman gain at the current time k representing the target time deviation; represents the observed value of the current time k of the target time deviation; H represents the observation matrix; The state estimate at the current time k representing the target time deviation; The expression of the covariance matrix of the predicted state of the updated target time deviation at the current moment is as follows: In the formula, The covariance matrix representing the predicted state at the current time k of the updated target time deviation; represents the Kalman gain of the current time k of the target time deviation; H represents the observation matrix; The covariance matrix of the predicted state at the current time k representing the target time deviation; When the state estimate and the covariance matrix reach a preset maximum update number, the current best estimate of the target time deviation is output.

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