Urban rail transit information safety protection method

Abstract

The invention discloses an urban rail transit information safety protection method, and relates to the technical field of information protection, and the method comprises the steps: building a ground wireless communication network, installing a reconfigurable surface structure on the surface of a leaky cable, determining the number of reflection units, and carrying out the real-time detection and early warning of data through artificial intelligence. The method has the advantages that the monitoring data of a plurality of safety management domains can be integrated by establishing cross-domain safety collaboration, comprehensive perception of the safety situation of the whole rail transit system is formed, network flow data, equipment operation state data, passenger behavior data and the like of different lines are integrated, and the safety of the whole rail transit system is improved. A safety situation awareness platform is constructed by using a data analysis technology, the safety condition of the system is monitored in real time, potential safety risks are found in advance, dynamic safety assessment can be performed on the rail transit system based on shared information and global safety situation awareness, and when it is found that a safety risk index exceeds a normal range, early warning can be given out in time.

Description

Technical Field

[0001] The present invention relates to the technical field of information protection, and in particular to an urban rail transit information security protection method. Background Art

[0002] Urban rail transit system refers to a transportation system that uses vehicles to run on fixed rails in cities and is mainly used for urban passenger transportation. It is a large-capacity, fast, punctual, safe and environmentally friendly public transportation mode, including subways, light rails, monorails, trams, maglev trains and other types. These different types of rail transit systems differ in track form, vehicle type, operation mode, etc., but all provide efficient transportation solutions for urban residents. In the current urban rail transit system, the communication-based train control system (CBTC) has been widely used. The CBTC system relies on wireless communication between the vehicle and the ground to achieve safe control of train operation; The information security protection experience and technical exchanges within the urban rail transit industry are insufficient, and there is a lack of effective information sharing mechanisms between different operating units. It is difficult to obtain the latest security threat intelligence and response measures in a timely manner, and it is impossible to form a joint force to jointly respond to information security challenges. To this end, we propose an urban rail transit information security protection method. Summary of the invention

[0003] The purpose of the present invention is to provide a method for protecting urban rail transit information security.

[0004] In order to solve the problems raised in the above background technology, the present invention provides the following technical solutions: a method for protecting the information security of urban rail transit, comprising establishing a ground wireless communication network, installing a reconfigurable surface structure on the surface of a leaking cable, determining the number of reflection units, and using artificial intelligence to detect and warn the data in real time. The specific operation steps of the method for protecting the information security of urban rail transit are as follows: Step 1: Establish a ground wireless communication network, and enable the train to communicate with the ground wireless communication network by installing on-board wireless system equipment; Step 2: installing a reconfigurable surface on the cable surface, and adjusting the phase shift direction of the reconfigurable surface to control the propagation direction of the electromagnetic wave; Step 3: Determine the number of reflection units on the surface of the leaky cable according to the expected improvement in the received signal-to-noise ratio; Step 4: Use blockchain technology to protect rail transit information; Step 5: Use cloud computing platforms to achieve cross-domain security collaboration and dynamically allocate resources through elastic computing; Step 6: Continuously optimize and adjust the platform based on AI-based security monitoring and early warning.

[0005] As a further solution of the present invention: in the step one, according to the business needs of urban rail transit, a ground wireless communication network is established. The wireless communication network adopts a honeycomb layout, and the base station is located at the center of the honeycomb. The wireless communication network adopts a leaky cable as a transmission medium, and selects 5GHz broadband as the communication frequency band to ensure stable transmission of signals along the rail transit line. After multiple base stations are installed, a network joint debugging test is performed to check the switching function between base stations. According to the results of the network opening test, areas with insufficient coverage and weak signals are optimized, and different component carriers are combined using carrier aggregation technology to provide a wider transmission bandwidth. On-board wireless system equipment is installed on the front of the rail transit train, including an on-board wireless terminal, an antenna and a feeder assembly. The on-board wireless system receives signals from the ground wireless communication network to enable communication between the train and the ground control center.

[0006] As a further solution of the present invention: in the step 2, a reconfigurable surface device is installed on the surface of the leakage cable, a liquid crystal material is selected as the main body of the reconfigurable surface, indium tin oxide is selected as the electrode material, the positive and negative poles of the power supply are respectively connected to the two electrodes of the liquid crystal reconfigurable surface through wires, the power supply voltage is set to 5V-50V, and in the process of applying the electric field, an electromagnetic measuring device is used to measure the phase shift change of the liquid crystal reconfigurable surface in real time, the direction of the electric field is adjusted by adjusting the voltage and changing the connection method of the power supply electrode, and the electric field strength and direction for achieving the desired phase shift direction change are determined according to the height of the vehicle-mounted antenna, the horizontal distance between the vehicle-mounted antenna and the leakage cable, and the height of each reflection unit according to the measured phase shift change data.

[0007] As a further solution of the present invention: In step 3, without setting a reflection unit, a spectrum analyzer is used to measure the received signal power and noise power around the leaking cable, and the initial signal-to-noise ratio is calculated. The calculation formula is: , in, represents the initial signal-to-noise ratio, represents the signal power, Represents the noise power. After adding N reflection units, the signal power becomes , the noise power becomes , after the signal-to-noise ratio is improved: , in, represents the signal power increment caused by N reflection units, Represents the noise power increment caused by N reflection units. Starting from N=1, the number of reflection units is gradually increased, and the signal power after each increase in reflection units is calculated. and noise power , get the corresponding signal-to-noise ratio SNR, observe the improvement trend of the signal-to-noise ratio as N increases, and calculate the expected improvement of the received signal-to-noise ratio according to the expected improvement of the received signal-to-noise ratio , find satisfaction in the simulation results The minimum number of reflective units .

[0008] As a further solution of the present invention: in the step four, the business process of rail transit is studied in depth, including train dispatching, ticket management, equipment monitoring, and passenger information. The flow direction, processing method and storage location of information in each link are analyzed, the producers, users and managers of information are clarified, and the security threats faced by rail transit information are identified, including leakage, tampering, loss, network attacks and malware intrusions. The possibility and potential impact of each security risk are evaluated, and the risk priority is determined. According to the security risk assessment results and business needs, blockchain is used to protect rail transit information, and the information is stored in encrypted form on the blockchain. The blockchain type is selected as a consortium chain, and the consortium is composed of rail transit operating companies, equipment suppliers and regulatory authorities. Each participating entity acts as a node to jointly manage and verify data and jointly maintain the blockchain.

[0009] As a further solution of the present invention: In the step 4, in the process of rail transit operation, in order to achieve efficient train scheduling, equipment maintenance and safety supervision functions, data needs to be shared between different entities. The alliance chain uses permission management and encryption technology to ensure data sharing while protecting the data privacy of each entity. When sharing data, a practical Byzantine fault-tolerant PBFT consensus algorithm is used to ensure the data consistency of each node in the alliance chain. In the event of faulty nodes and malicious nodes, other nodes are guaranteed to correctly record and process data. The PBFT fast consensus feature enables data to be quickly agreed upon and recorded between multiple nodes, and the system data is updated and processed in real time.

[0010] As a further solution of the present invention: in the step five, cross-domain security collaboration is established between different security management domains, including different rail transit lines and different urban transportation systems. By establishing a cooperation mechanism, a unified security strategy and collaborative security technical means, the operating companies of different lines cooperate with each other. Through cross-regional security collaboration and information sharing, the operating companies in different regions share attack characteristics and response strategies, and unite to jointly resist diverse and cross-regional security threats. A distributed sharing platform is built through cloud computing technology, and data is stored in different physical nodes in a dispersed manner. The data is encrypted by an encryption algorithm before storage. The cloud computing platform integrates a large number of physical servers, storage devices and network devices to form a resource pool. The cloud computing platform will monitor the usage of various resources in the resource pool in real time. According to the results of resource monitoring, the scheduling system of the cloud computing platform will automatically allocate and adjust resources. When the user's application needs more resources, the cloud computing platform will allocate additional resources to the user from the resource pool. When the user's demand decreases, the cloud computing platform will recycle some resources for other users and reduce energy consumption.

[0011] As a further solution of the present invention: in the step six, data is collected from various links of the rail transit information sharing platform, including network traffic data, system logs, user behavior data and data generated by security devices (firewalls and intrusion detection systems), network traffic data is collected through a network packet capture tool, and system logs are collected using a log management system. Duplicate data records are removed, erroneous data values ​​are corrected, and missing data are filled in. Meaningful features are extracted from the cleaned data. For network traffic data, source IP address, destination IP address, port number, data packet size and traffic frequency features are extracted. For system logs, event type, timestamp and user ID features are extracted. The neural network intelligent model is trained using the labeled training data. After the training, the real-time collected data is input into the neural network intelligent model. The model predicts the data according to the learned pattern, and filters the false alarms by establishing a false alarm filtering mechanism, setting reasonable thresholds, and analyzing the duration and frequency factors of the abnormalities.

[0012] As a further solution of the present invention: in step six, all data access operations, system configuration changes, and transaction record information are recorded in the audit log of the blockchain. Due to the tamper-proof nature of the blockchain, when a security incident occurs, the blockchain audit log can be used to quickly locate the transaction origin, intermediate circulation links, and related personnel and equipment involved. Combined with artificial intelligence and big data analysis technology, the audit data on the blockchain is monitored and analyzed in real time. By establishing an abnormal behavior detection model, potential security threats and illegal operations are discovered in a timely manner. By analyzing the access pattern of train operation data, when it is found that an external IP address frequently accesses a large amount of train operation parameter data in a short period of time and does not conform to normal business logic, the system automatically takes corresponding security protection measures to temporarily block access and encrypt the data for protection.

[0013] By adopting the above technical solution, compared with the prior art, the beneficial effects of the present invention are: 1. The present invention can integrate the monitoring data of multiple security management domains by establishing cross-domain security collaboration, form a comprehensive perception of the security situation of the entire rail transit system, integrate network traffic data, equipment operation status data and passenger behavior data of different lines, and use data analysis technology to build a security situation awareness platform to monitor the security status of the system in real time and discover potential security risks in advance. Based on shared information and global security situation awareness, it can conduct dynamic security assessments on the rail transit system. When it is found that the security risk indicators exceed the normal range, it can issue early warnings in time. By analyzing ticket sales data and passenger flow data in different regions, abnormal ticket transaction patterns can be discovered, indicating ticket fraud or security threats, so that preventive measures can be taken in advance; 2. The present invention installs a reconfigurable surface device on the surface of the leaking cable and accurately adjusts the phase shift direction of the reflection unit, effectively limiting the wireless signal coverage within the range of the rail transit line, significantly reducing the risk of signal leakage outside the line, enhancing the information security of urban rail transit wireless communications, providing more reliable communication guarantees for train operation, optimizing model transmission paths, reducing signal attenuation and interference, thereby improving communication quality, ensuring stable communication between trains and ground control centers, and flexibly adjusting the phase shift direction of the reflection unit to meet the needs of different rail transit lines and train operating conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 Schematic diagram of the steps for protecting urban rail transit information security in an embodiment of the present invention. DETAILED DESCRIPTION

[0015] The specific embodiments of the present invention are further described below in conjunction with the accompanying drawings. It should be noted that the description of these embodiments is used to help understand the present invention, but does not constitute a limitation of the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0016] The present invention provides a method for protecting the information security of urban rail transit, including establishing a ground wireless communication network, installing a reconfigurable surface structure on the surface of a leaking cable, determining the number of reflection units, and using artificial intelligence to detect and warn data in real time. The specific operation steps of the method for protecting the information security of urban rail transit are as follows: Step 1: Establish a ground wireless communication network, and enable the train to communicate with the ground wireless communication network by installing on-board wireless system equipment; Step 2: installing a reconfigurable surface on the cable surface, and adjusting the phase shift direction of the reconfigurable surface to control the propagation direction of the electromagnetic wave; Step 3: Determine the number of reflection units on the surface of the leaky cable according to the expected improvement in the received signal-to-noise ratio; Step 4: Use blockchain technology to protect rail transit information; Step 5: Use cloud computing platforms to achieve cross-domain security collaboration and dynamically allocate resources through elastic computing; Step 6: Continuously optimize and adjust the platform based on AI-based security monitoring and early warning.

[0017] In one embodiment of the present invention: in step one, according to the business needs of urban rail transit, a ground wireless communication network is established. The wireless communication network adopts a honeycomb layout, and the base station is located at the center of the honeycomb. The wireless communication network adopts a leaky cable as a transmission medium and selects 5 GHz broadband as the communication frequency band to ensure stable transmission of signals along the rail transit line. When multiple base stations are installed, a network joint debugging test is performed to check the switching function between base stations. According to the results of the network opening test, areas with insufficient coverage and weak signals are optimized. Different component carriers are combined using carrier aggregation technology to provide a wider transmission bandwidth. On-board wireless system equipment is installed on the front of the rail transit train, including an on-board wireless terminal, an antenna and a feeder assembly. The on-board wireless system receives signals from the ground wireless communication network to enable communication between the train and the ground control center.

[0018] In one embodiment of the present invention: in step 2, a reconfigurable surface device is installed on the surface of the leakage cable, a liquid crystal material is selected as the main body of the reconfigurable surface, indium tin oxide is selected as the electrode material, the positive and negative poles of the power supply are respectively connected to the two electrodes of the liquid crystal reconfigurable surface through wires, and the power supply voltage is set to 5V-50V. In the process of applying an electric field, an electromagnetic measuring device is used to measure the phase shift change of the liquid crystal reconfigurable surface in real time, and the direction of the electric field is adjusted by adjusting the voltage and changing the connection method of the power supply electrode. According to the height of the vehicle-mounted antenna, the horizontal distance between the vehicle-mounted antenna and the leakage cable, and the height of each reflection unit, the electric field strength and direction for achieving the required phase shift direction change are determined according to the measured phase shift change data.

[0019] In one embodiment of the present invention: In step 3, without setting a reflection unit, a spectrum analyzer is used to measure the received signal power and noise power around the leaking cable, and the initial signal-to-noise ratio is calculated. The calculation formula is: , in, represents the initial signal-to-noise ratio, represents the signal power, Represents the noise power. After adding N reflection units, the signal power becomes , the noise power becomes , after the signal-to-noise ratio is improved: , in, represents the signal power increment caused by N reflection units, Represents the noise power increment caused by N reflection units. Starting from N=1, the number of reflection units is gradually increased, and the signal power after each increase in reflection units is calculated. and noise power , get the corresponding signal-to-noise ratio SNR, observe the improvement trend of the signal-to-noise ratio as N increases, and calculate the expected improvement of the received signal-to-noise ratio according to the expected improvement of the received signal-to-noise ratio , find satisfaction in the simulation results The minimum number of reflective units .

[0020] In one embodiment of the present invention: In step four, the business process of rail transit is studied in depth, including train dispatching, ticket management, equipment monitoring, and passenger information. The flow direction, processing method, and storage location of information in each link are analyzed, the producers, users, and managers of information are clarified, and the security threats faced by rail transit information are identified, including leakage, tampering, loss, network attacks, and malware intrusions. The possibility and potential impact of each security risk are evaluated, and the risk priority is determined. According to the security risk assessment results and business needs, blockchain is used to protect rail transit information, and the information is stored in an encrypted form on the blockchain. The blockchain type uses a consortium chain, which is composed of rail transit operating companies, equipment suppliers, and regulatory authorities. Each participating entity acts as a node to jointly manage and verify data and jointly maintain the blockchain.

[0021] In one embodiment of the present invention: In step four, during the operation of rail transit, in order to achieve efficient train scheduling, equipment maintenance and safety supervision functions, data needs to be shared between different entities. The alliance chain uses permission management and encryption technology to ensure data sharing while protecting the data privacy of each entity. When sharing data, a practical Byzantine fault-tolerant PBFT consensus algorithm is used to ensure data consistency among nodes in the alliance chain. In the event of faulty nodes and malicious nodes, other nodes are guaranteed to correctly record and process data. The PBFT fast consensus feature enables data to be quickly agreed upon and recorded between multiple nodes, and the system data is updated and processed in real time.

[0022] In one embodiment of the present invention: In step five, cross-domain security collaboration is established between different security management domains, including different rail transit lines and different urban transportation systems. By establishing a cooperation mechanism, a unified security strategy and collaborative security technical means, the operating companies of different lines cooperate with each other. Through cross-regional security collaboration and information sharing, the operating companies in different regions share attack characteristics and response strategies, and unite to jointly resist diverse and cross-regional security threats. A distributed sharing platform is built through cloud computing technology, and data is stored in different physical nodes in a dispersed manner. The data is encrypted by an encryption algorithm before storage. The cloud computing platform integrates a large number of physical servers, storage devices and network devices to form a resource pool. The cloud computing platform will monitor the usage of various resources in the resource pool in real time. According to the results of resource monitoring, the scheduling system of the cloud computing platform will automatically allocate and adjust resources. When the user's application needs more resources, the cloud computing platform will allocate additional resources to the user from the resource pool. When the user's demand decreases, the cloud computing platform will recycle some resources for other users and reduce energy consumption.

[0023] In one embodiment of the present invention: In step six, data is collected from various links of the rail transit information sharing platform, including network traffic data, system logs, user behavior data, and data generated by security devices (firewalls and intrusion detection systems). Network traffic data is collected through a network packet capture tool, and system logs are collected using a log management system. Duplicate data records are removed, erroneous data values ​​are corrected, and missing data is filled in. Meaningful features are extracted from the cleaned data. For network traffic data, source IP address, destination IP address, port number, data packet size, and traffic frequency features are extracted. For system logs, event type, timestamp, and user ID features are extracted. The neural network intelligent model is trained using the labeled training data. After the training, the real-time collected data is input into the neural network intelligent model. The model predicts the data according to the learned pattern, and filters the false alarms by establishing a false alarm filtering mechanism, setting reasonable thresholds, and analyzing the duration and frequency factors of the abnormalities.

[0024] In one embodiment of the present invention: In step six, all data access operations, system configuration changes, and transaction record information are recorded in the audit log of the blockchain. Due to the tamper-proof nature of the blockchain, when a security incident occurs, the blockchain audit log can be used to quickly locate the transaction origin, intermediate circulation links, and related personnel and equipment involved. Combined with artificial intelligence and big data analysis technology, the audit data on the blockchain is monitored and analyzed in real time. By establishing an abnormal behavior detection model, potential security threats and illegal operations are discovered in a timely manner. By analyzing the access pattern of train operation data, when it is found that an external IP address frequently accesses a large amount of train operation parameter data in a short period of time and does not conform to normal business logic, the system automatically takes corresponding security protection measures to temporarily block access and encrypt the data for protection.

[0025] Embodiment 1: The Byzantine fault tolerance capability of PBFT can enhance the reliability of the rail transit alliance chain. In a complex network environment and possible node failures or attacks, the system can continue to operate normally through the PBFT mechanism to ensure data consistency and service continuity. Even if some station nodes or equipment supplier nodes fail, train operation data can still be correctly recorded and updated between other normal nodes to ensure that train scheduling is not affected.

[0026] Embodiment 2: Rail transit safety management involves a variety of security applications and services, such as intrusion detection systems, security situation awareness systems, and emergency command systems. These applications and services have different requirements for computing resources and may need to be dynamically deployed and adjusted according to actual conditions. In daily security management, the intrusion detection system may only need fewer resources to monitor network traffic. When suspicious signs of network attacks are found, it may be necessary to quickly increase resources for in-depth detection and analysis. Elastic computing resources can dynamically allocate CPU, memory, storage and other resources to security applications according to their needs, supporting flexible deployment and efficient operation of these applications.

[0027] Embodiment 3: The resource pool of the cloud computing platform adopts a redundant and fault-tolerant design. By allocating resources among multiple physical servers and data centers, even if a server or data center fails, the system can still continue to operate through other normal resources. This design improves the reliability of the system, which is very important for application scenarios such as rail transit safety information sharing that have high requirements for continuity. The storage resources of the cloud computing platform may be distributed in multiple data centers. By using data redundancy technology, when a fire or other disaster occurs in a data center and causes some storage devices to be damaged, the backup data of other data centers can ensure that security information is not lost, and the system can still provide information sharing services normally.

[0028] As attached Figure 1 As shown, by installing a reconfigurable surface and adjusting the phase shift of the reflection unit, the signal coverage range can be effectively limited, signal leakage can be significantly reduced, information security can be enhanced, and communication quality can be improved.

[0029] The embodiments of the present invention are described in detail above with reference to the accompanying drawings, but the present invention is not limited to the described embodiments. For those skilled in the art, various changes, modifications, substitutions and variations of these embodiments are made without departing from the principles and spirit of the present invention, and still fall within the scope of protection of the present invention.

[0030] In the description of the specification, the description with reference to the terms "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0031] The above contents are merely examples and explanations of the present invention. Various modifications or additions to the specific embodiments described or replacements in similar ways by technicians in the technical field shall fall within the protection scope of the present invention as long as they do not deviate from the invention or exceed the scope defined by the claims.

[0032] 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 technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A method for protecting information security of urban rail transit, comprising establishing a ground wireless communication network, installing a reconfigurable surface structure on the surface of a leaking cable, determining the number of reflection units, and using artificial intelligence to detect and warn data in real time, characterized in that: The specific operation steps of the urban rail transit information security protection method are as follows: Step 1: Establish a ground wireless communication network, and enable the train to communicate with the ground wireless communication network by installing on-board wireless system equipment; Step 2: installing a reconfigurable surface on the cable surface, and adjusting the phase shift direction of the reconfigurable surface to control the propagation direction of the electromagnetic wave; Step 3: Determine the number of reflection units on the surface of the leaky cable according to the expected improvement in the received signal-to-noise ratio; Step 4: Use blockchain technology to protect rail transit information; Step 5: Use cloud computing platforms to achieve cross-domain security collaboration and dynamically allocate resources through elastic computing; Step 6: Continuously optimize and adjust the platform based on AI-based security monitoring and early warning.

2. The urban rail transit information security protection method according to claim 1 is characterized in that: In the step 1, according to the business needs of urban rail transit, a ground wireless communication network is established. The wireless communication network adopts a honeycomb layout, and the base station is located at the center of the honeycomb. The wireless communication network uses leaky cables as transmission media and selects 5 GHz broadband as the communication frequency band to ensure stable transmission of signals along the rail transit line. When multiple base stations are installed, a network joint debugging test is performed to check the switching function between base stations. According to the results of the network opening test, the areas with insufficient coverage and weak signals are optimized. Different component carriers are combined using carrier aggregation technology to provide a wider transmission bandwidth. On-board wireless system equipment, including on-board wireless terminals, antennas and feeder components, is installed on the front of the rail transit train. The on-board wireless system receives signals from the ground wireless communication network to enable communication between the train and the ground control center.

3. The urban rail transit information security protection method according to claim 2 is characterized in that: In the step 2, a reconfigurable surface device is installed on the surface of the leakage cable, a liquid crystal material is selected as the main body of the reconfigurable surface, and indium tin oxide is selected as the electrode material. The positive and negative poles of the power supply are respectively connected to the two electrodes of the liquid crystal reconfigurable surface through wires, and the power supply voltage is set to 5V-50V. In the process of applying the electric field, an electromagnetic measurement device is used to measure the phase shift change of the liquid crystal reconfigurable surface in real time. The direction of the electric field is adjusted by adjusting the voltage and changing the connection method of the power supply electrode. According to the height of the vehicle-mounted antenna, the horizontal distance between the vehicle-mounted antenna and the leakage cable, and the height of each reflection unit, the electric field strength and direction for achieving the required phase shift direction change are determined according to the measured phase shift change data.

4. The urban rail transit information security protection method according to claim 3 is characterized in that: In step 3, without setting a reflection unit, a spectrum analyzer is used to measure the received signal power and noise power around the leaking cable, and the initial signal-to-noise ratio is calculated using the following formula: ， in, represents the initial signal-to-noise ratio, represents the signal power, Represents the noise power. After adding N reflection units, the signal power becomes , the noise power becomes , after the signal-to-noise ratio is improved: ， in, represents the signal power increment caused by N reflection units, Represents the noise power increment caused by N reflection units. Starting from N=1, the number of reflection units is gradually increased, and the signal power after each increase in reflection units is calculated. and noise power , get the corresponding signal-to-noise ratio SNR, observe the improvement trend of the signal-to-noise ratio as N increases, and calculate the expected improvement of the received signal-to-noise ratio according to the expected improvement of the received signal-to-noise ratio , find satisfaction in the simulation results The minimum number of reflection units .

5. The urban rail transit information security protection method according to claim 1 is characterized in that: In the fourth step, the business process of rail transit is studied in depth, including train dispatching, ticket management, equipment monitoring, and passenger information. The flow direction, processing method, and storage location of information in each link are analyzed. The producers, users, and managers of information are clarified. The security threats faced by rail transit information are identified, including leakage, tampering, loss, network attacks, and malware intrusions. The possibility and potential impact of each security risk are evaluated, and the risk priority is determined. According to the security risk assessment results and business needs, blockchain is used to protect rail transit information. The information is stored in an encrypted form on the blockchain. The blockchain type is a consortium chain, which is composed of rail transit operating companies, equipment suppliers, and regulatory authorities. Each participating entity acts as a node to jointly manage and verify data and jointly maintain the blockchain.

6. The urban rail transit information security protection method according to claim 5 is characterized by: In step 4, in the process of rail transit operation, in order to achieve efficient train scheduling, equipment maintenance and safety supervision functions, data needs to be shared between different entities. The alliance chain uses permission management and encryption technology to ensure data sharing while protecting the data privacy of each entity. When sharing data, the practical Byzantine fault-tolerant PBFT consensus algorithm is used to ensure the data consistency of each node in the alliance chain. In the event of faulty nodes and malicious nodes, other nodes are guaranteed to correctly record and process data. The PBFT fast consensus feature allows data to be quickly agreed upon and recorded between multiple nodes, and the system data is updated and processed in real time.

7. The urban rail transit information security protection method according to claim 1 is characterized by: In the step five, cross-domain security collaboration is established between different security management domains, including different rail transit lines and different urban transportation systems. By establishing a cooperation mechanism, a unified security strategy and collaborative security technical means, the operating companies of different lines cooperate with each other. Through cross-regional security collaboration and information sharing, the operating companies in different regions share attack characteristics and response strategies, and unite to jointly resist diverse and cross-regional security threats. A distributed sharing platform is built through cloud computing technology, and data is stored in different physical nodes in a dispersed manner. The data is encrypted by an encryption algorithm before storage. The cloud computing platform integrates a large number of physical servers, storage devices and network devices to form a resource pool. The cloud computing platform will monitor the usage of various resources in the resource pool in real time. According to the results of resource monitoring, the scheduling system of the cloud computing platform will automatically allocate and adjust resources. When the user's application needs more resources, the cloud computing platform will allocate additional resources to the user from the resource pool. When the user's demand decreases, the cloud computing platform will recycle some resources for other users and reduce energy consumption.

8. The urban rail transit information security protection method according to claim 7 is characterized in that: In the step six, data is collected from various links of the rail transit information sharing platform, including network traffic data, system logs, user behavior data and data generated by security devices. Network traffic data is collected through network packet capture tools, and system logs are collected using a log management system. Duplicate data records are removed, erroneous data values ​​are corrected, and missing data is filled in. Meaningful features are extracted from the cleaned data. For network traffic data, source IP address, destination IP address, port number, data packet size and traffic frequency features are extracted. For system logs, event type, timestamp and user ID features are extracted. The neural network intelligent model is trained using labeled training data. After the training, the real-time collected data is input into the neural network intelligent model. The model predicts the data according to the learned pattern, and filters false alarms by establishing a false alarm filtering mechanism, setting reasonable thresholds, and analyzing the duration and frequency factors of abnormalities.

9. The urban rail transit information security protection method according to claim 8, characterized in that: In step six, all data access operations, system configuration changes, and transaction record information are recorded in the audit log of the blockchain. Due to the tamper-proof nature of the blockchain, when a security incident occurs, the blockchain audit log can be used to quickly locate the transaction origin, intermediate circulation links, and related personnel and equipment involved. Combined with artificial intelligence and big data analysis technology, the audit data on the blockchain is monitored and analyzed in real time. By establishing an abnormal behavior detection model, potential security threats and illegal operations are discovered in a timely manner. By analyzing the access pattern of train operation data, when it is found that an external IP address frequently accesses a large amount of train operation parameter data in a short period of time and does not conform to normal business logic, the system automatically takes corresponding security protection measures to temporarily block access and encrypt the data for protection.

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