Long-distance emergency communication network system based on wireless ad hoc network

Abstract

The application discloses a kind of long-distance emergency communication network systems based on wireless ad hoc network, including distributed Mesh network architecture, M-AODV wireless ad hoc network routing protocol, ad hoc network reconstruction algorithm, RSA and AES hybrid encryption communication algorithm;The distributed Mesh network architecture is the overall structure of entire emergency communication network;The M-AODV wireless ad hoc network routing protocol is the path establishment and maintenance mechanism inside network architecture;The ad hoc network reconstruction algorithm is the fault recovery and topology reconstruction mechanism in network architecture, and the RSA and AES hybrid encryption communication algorithm is the security mechanism of service data transmission.The application recovers quickly by ad hoc network reconstruction algorithm, and guarantees the continuity of communication, with strong security, using RSA and AES hybrid encryption communication algorithm, to prevent data eavesdropping and illegal intrusion, using M-AODV wireless ad hoc network routing protocol, to improve the overall stability of network, and distributed Mesh network architecture supports multi-hop relay, breaks through the terrain limit, and realizes long-distance communication.

Description

Technical Field

[0001] This invention belongs to the field of wireless communication technology, and in particular relates to a long-distance emergency communication network system based on a wireless ad hoc network. Background Technology

[0002] In complex emergency communication scenarios, such as mountainous areas and mines, traditional communication networks suffer from insufficient base station coverage, signal obstruction by terrain, and limited communication distance. This is especially true in large-scale overseas EPC projects, where complex and variable terrain makes conventional communication methods insufficient to meet the demands for long-distance, high-reliability emergency communication. Wireless mesh ad hoc networking technology, with its self-organizing, self-configuring, and self-maintaining characteristics, has become an effective means of solving these problems. However, existing wireless mesh ad hoc networking technologies still have shortcomings in dynamic topology adjustment, anti-interference capabilities, and secure communication. Summary of the Invention

[0003] The main technical problem solved by this invention is to provide a long-distance emergency communication network system based on a wireless self-organizing network, which realizes high reliability, high security, and dynamic self-adaptation for long-distance emergency communication, and is suitable for emergency communication needs in complex environments.

[0004] To solve the above-mentioned technical problems, one technical solution adopted by the present invention is: a long-distance emergency communication network system based on a wireless ad hoc network, including a distributed Mesh network architecture, an M-AODV wireless ad hoc network routing protocol, an ad hoc network reconfiguration algorithm, and a hybrid encryption communication algorithm of RSA and AES; The distributed mesh network architecture is the overall structure of the entire emergency communication network; The M-AODV wireless ad hoc network routing protocol is a path establishment and maintenance mechanism within the network architecture; The self-organizing network reconfiguration algorithm is a fault recovery and topology reconstruction mechanism in the network architecture. The relationship between the reconfiguration algorithm and routing is as follows: routing selects a route on the current topology, while reconfiguration repairs or rebuilds the topology after it is broken. After reconfiguration, the routing protocol continues to select routes and forward based on the new topology. The RSA and AES hybrid encryption communication algorithm is a security mechanism for business data transmission, operating as a security protection layer during the communication process.

[0005] Furthermore, the distributed mesh network architecture consists of multiple wireless mesh network terminal nodes with integrated routing capabilities. Long-distance communication between nodes is achieved through multi-hop relays. The network architecture includes the following core components: System Nodes: Each node consists of a control unit and a wireless communication unit. The control unit is responsible for data storage and routing control, while the wireless communication unit is responsible for data transmission and reception. Time synchronization module: Ensures network-wide time synchronization and provides a time reference for multi-hop transmission; Control Center: Responsible for network-wide monitoring and data analysis, and provides a user interface; Power module: Provides stable power support for nodes; some nodes can be equipped with solar renewable energy.

[0006] Furthermore, the M-AODV wireless ad hoc network routing protocol includes route discovery and route maintenance; The route discovery process is similar to the traditional AODV, but it takes into account the problems of low remaining energy of nodes causing energy depletion and low received signal strength potentially causing link instability. During the path selection process, thresholds are set for the remaining energy of nodes and the received signal strength to prevent nodes with low energy and paths with low received signal strength (i.e., unstable links) from participating in the route transmission, thereby improving the performance of the routing protocol. When a source node sends a message to a destination node, it first checks its own routing table for a route to the destination. If no route exists, the data packet is stored in the source node's data buffer, and then route discovery is enabled. The difference is that the modified protocol checks the received signal strength of neighboring nodes in the source node's neighbor table before sending the message. If the received signal strength is greater than or equal to a received signal threshold, then it calculates... Its formula is in Let be the threshold value of the received signal strength of node j from its neighbor node i. The received signal strength; Calculated The RSSM field is stored in the corresponding location, and then an RREQ route request packet is generated to the neighboring node. When a node receives an RREQ message, it first determines whether to call the function in the route discovery process. If the node is an intermediate node, it first compares the remaining energy of the intermediate node with the energy threshold. If the remaining energy is less than the capacity threshold, the node is discarded. The purpose is to prevent nodes with too low energy from continuing to participate in the forwarding of RREQ packets, which could cause the node to die quickly, leading to network regionalization and the inability to obtain a path to the destination. This would require re-discovering the path, increasing both energy consumption and transmission complexity in the network. If the remaining energy is greater than the capacity threshold, the node will continue to forward data. When receiving RREP route packets, it first determines whether the node is the destination node. If not, it updates the route to the destination node and forwards the data according to the reverse route established during the forwarding RREQ process. If the node is the source node in RREQ, it starts a timing mechanism when it receives the packet for the first time, and saves the congestion level and received signal strength in RREP. Then, it calculates the reliability value of the path according to the path reliability function. When the timing mechanism ends, it selects the path with the highest reliability from among many paths as the optimal path for data transmission. The formula for the path reliability function is as follows: in For congestion measurement, Measured by the number of hops; Energy is also crucial for optimizing routing protocols during the routing process. Before data forwarding, the energy of each node is considered: a threshold for the remaining energy of a node is defined. During the first route discovery process, a node that receives an RREQ packet checks whether its remaining energy is greater than the corresponding threshold. If it is greater than the threshold, the RREQ packet is forwarded; otherwise, the packet is discarded.

[0007] Furthermore, in the M-AODV routing algorithm, nodes broadcast HELLO messages at fixed time intervals to detect the connectivity status of links with neighboring nodes. When a node fails to receive a valid response from a neighboring node within a specified time, it can be assumed that the link with that neighbor may have been interrupted. If the link happens to be on the current data forwarding path, the route maintenance process is initiated. For link interruption issues, the protocol prioritizes a local repair mechanism, that is, the upstream node at the break point initiates a new route request to restore communication as much as possible in a local area, reducing the latency and overhead caused by re-initiating the whole network route discovery. If the local repair is successful within the specified time, data transmission continues along the newly established path. If the local repair fails, the relevant node sends a RERR message to the upstream node to notify that the original route has failed, until the source node receives the error message and restarts the route discovery process.

[0008] Furthermore, the self-organizing network reconfiguration algorithm includes fault detection, fault location, reconfiguration strategy, and topology optimization.

[0009] Furthermore, fault detection is the foundation of refactoring. The algorithm monitors node status in real time by periodically sending "heartbeat" messages between nodes, setting the time interval for each node to send a "heartbeat" packet to be [missing information]. If node At any moment To the node Send a "heartbeat" packet, in No node received at any time The response, and after If no response is received after the second retrieval, then the node is preliminarily determined to be... In the event of a failure, the node continuously monitors the signal strength of its own communication link. and bit error rate To assess link quality, a lower threshold for signal strength is set. The upper limit threshold for the bit error rate is Introducing a link quality evaluation function : when This indicates that there is a risk of failure in the link.

[0010] Furthermore, once a fault is detected, the fault location procedure is immediately initiated. Using a distributed fault location method, the node that detects the fault broadcasts the fault information to surrounding nodes. The nodes that receive the fault information make a preliminary judgment on the fault location based on their stored network topology information and routing tables, and then feed back the relevant information to the node that initiated the fault detection. Through information interaction and comprehensive analysis among multiple nodes, the specific location of the faulty node and link can be accurately determined.

[0011] Furthermore, the reconstruction strategy is as follows: After identifying the fault location, when node i fails and leaves the network, all its neighboring nodes can detect the fault immediately and run the algorithm. The computational complexity of the algorithm is mainly related to the degree of the faulty network node. When a large number of network nodes experience communication failures, the topology can be quickly reconstructed. In addition, to further optimize the algorithm's running time, it is mainly based on the breadth-first search (BFS) algorithm to obtain the spanning tree. Its basic idea is to start from the root node, traverse the graph until all nodes in the graph are visited, and finally generate a breadth-first search tree. The time complexity of the algorithm is O(V+E), where V and E represent the number of nodes and the number of edges in the ad hoc network, respectively. The specific algorithm is as follows: Input: The current global adjacency matrix A, and the IDs of the faulty network nodes. The current parent and child node numbers of the node. , k=1,2,... Output: The reconstructed parent node number (NLR) and the newly added child node number. k=1,2,... Step 1: Let = ; Step 2: Based on the current global adjacency matrix and faulty network node number Construct the set of neighbor nodes of the faulty node. ; Step 3: In Remove the faulty node, all edges associated with the faulty node, and the set of nodes excluding its neighbors. All nodes and related edges outside the local boundary are considered to construct a local adjacency matrix containing only adjacent nodes. ; Step 4: Select the set of neighboring nodes The node with the smallest index is selected as the root node, and the local adjacency matrix is ​​calculated based on the BFS algorithm. Spanning tree in ; Step 5: Based on the spanning tree Find the parent and child node numbers after topology reconstruction. , If k=1,2,... and Then update The parent node of the root node is .

[0012] Furthermore, during the reconstruction process, it is necessary to focus on optimizing the network topology and taking into account the remaining power of the nodes. Communication load Factors that dynamically adjust the connection relationships between nodes can lead to a more balanced distribution of network load. For example, if there are factors in the network... Nodes, Nodes The remaining power is The communication load is The average remaining power of the network is The average communication load is The following objective function is minimized through an optimization algorithm: The formula enables a balanced distribution of network load, improving the overall stability and reliability of the network and extending its lifespan.

[0013] The beneficial effects of the present invention include at least the following: This invention uses a self-organizing network reconstruction algorithm to quickly restore faulty nodes or links, ensuring communication continuity and providing strong security. It employs a hybrid encryption communication algorithm of RSA and AES to prevent data eavesdropping and illegal intrusion, and uses the M-AODV wireless self-organizing network routing protocol to improve the overall stability of the network. The distributed mesh network architecture supports multi-hop relay, breaking through terrain limitations and enabling long-distance communication. The distributed Mesh network architecture of this invention utilizes the self-organizing characteristics of Mesh self-organizing networks to automatically discover and establish new communication paths. Once a suitable path is found, data is transmitted immediately, ensuring unimpeded emergency communication. The wireless ad hoc network routing protocol of this invention comprehensively considers received signal strength, congestion level, remaining energy of nodes, and hop count during path selection. It calculates path reliability based on received signal strength, congestion level, and hop count, and sets an energy threshold to prevent nodes with low energy from transmitting data. The M-AODV wireless ad hoc network routing protocol provides efficient and reliable routing decisions for wireless ad hoc networks, adapting to node mobility and link instability. By improving route discovery and maintenance strategies and introducing multi-dimensional metrics, it significantly improves the performance of wireless ad hoc networks in dynamic environments, making it particularly suitable for large-scale overseas EPC projects. Attached Figure Description

[0014] Figure 1 It is a distributed mesh network architecture; Figure 2 This describes the processing flow after a node receives a RERR message. Detailed Implementation

[0015] The preferred embodiments of the present invention will now be described in detail so that the advantages and features of the present invention can be more easily understood by those skilled in the art, thereby providing a clearer and more explicit definition of the scope of protection of the present invention.

[0016] Example: A long-distance emergency communication network system based on a wireless ad hoc network, including a distributed mesh network architecture, an M-AODV wireless ad hoc network routing protocol, an ad hoc network reconfiguration algorithm, and a hybrid RSA and AES encrypted communication algorithm; The distributed mesh network architecture is the overall structure of the entire emergency communication network; The M-AODV wireless ad hoc network routing protocol is a path establishment and maintenance mechanism within the network architecture; The self-organizing network reconfiguration algorithm is a fault recovery and topology reconstruction mechanism in the network architecture. The relationship between the reconfiguration algorithm and routing is as follows: routing selects a route on the current topology, while reconfiguration repairs or rebuilds the topology after it is broken. After reconfiguration, the routing protocol continues to select routes and forward based on the new topology. The RSA and AES hybrid encryption communication algorithm is a security mechanism for business data transmission, operating as a security protection layer during the communication process.

[0017] The distributed mesh network architecture consists of multiple wireless mesh network terminal nodes with integrated routing capabilities. Long-distance communication between nodes is achieved through multi-hop relays, such as... Figure 1 As shown, the network architecture includes the following core components: System Nodes: Each node consists of a control unit and a wireless communication unit. The control unit is responsible for data storage and routing control, while the wireless communication unit is responsible for data transmission and reception. Time synchronization module: Ensures network-wide time synchronization and provides a time reference for multi-hop transmission; Control Center: Responsible for network-wide monitoring and data analysis, and provides a user interface; Power module: Provides stable power support for nodes; some nodes can be equipped with solar renewable energy.

[0018] The power module and timing module are connected to the system node, and the system node is wirelessly connected to the control center.

[0019] In emergency environments, network conditions are complex and changeable. If there is no suitable route in the routing table, such as when the original transmission path is interrupted due to disasters or other factors, the node will quickly start the route lookup function. Utilizing the self-organizing characteristics of the Mesh self-organizing network, it will automatically discover and establish a new communication path. Once a suitable path is found, data will be transmitted immediately to ensure uninterrupted emergency communication.

[0020] When deploying nodes, it is necessary to select locations with open views and high elevations based on the terrain features to ensure stable communication links between nodes. Through on-site surveys and signal simulation tests, the node density should be reasonably planned to balance coverage and interference issues. Nodes should establish multi-hop paths through dynamic routing protocols to overcome the coverage limitations of a single node and achieve long-distance signal transmission.

[0021] The M-AODV wireless ad hoc network routing protocol includes route discovery and route maintenance. During the route discovery process, signal strength measurement, congestion measurement, and remaining energy have been added, and the path selection criteria have been changed so that the modified AODV routing protocol can select a more reliable path as the optimal path for data transmission. The route discovery process is similar to the traditional AODV, but it takes into account the problems of low remaining energy of nodes causing energy depletion and low received signal strength potentially causing link instability. During the path selection process, thresholds are set for the remaining energy of nodes and the received signal strength to prevent nodes with low energy and paths with low received signal strength (i.e., unstable links) from participating in the route transmission, thereby improving the performance of the routing protocol. When a source node sends a message to a destination node, it first checks its own routing table for a route to the destination. If no route exists, the data packet is stored in the source node's data buffer, and then route discovery is enabled. The difference is that the modified protocol checks the received signal strength of neighboring nodes in the source node's neighbor table before sending the message. If the received signal strength is greater than or equal to a received signal threshold, then it calculates... Its formula is in Let be the threshold value of the received signal strength of node j from its neighbor node i. The received signal strength; Calculated The RSSM field is stored in the corresponding location, and then an RREQ route request packet is generated to the neighboring node. When a node receives an RREQ message, it first determines whether to call the function in the route discovery process. If the node is an intermediate node, it first compares the remaining energy of the intermediate node with the energy threshold. If the remaining energy is less than the capacity threshold, the node is discarded. The purpose is to prevent nodes with too low energy from continuing to participate in the forwarding of RREQ packets, which could cause the node to die quickly, leading to network regionalization and the inability to obtain a path to the destination. This would require re-discovering the path, increasing both energy consumption and transmission complexity in the network. If the remaining energy is greater than the capacity threshold, the node will continue to forward data. When receiving RREP route packets, it first determines whether the node is the destination node. If not, it updates the route to the destination node and forwards the data according to the reverse route established during the forwarding RREQ process. If the node is the source node in RREQ, it starts a timing mechanism when it receives the packet for the first time, and saves the congestion level and received signal strength in RREP. Then, it calculates the reliability value of the path according to the path reliability function. When the timing mechanism ends, it selects the path with the highest reliability from among many paths as the optimal path for data transmission. The formula for the path reliability function is as follows: in For congestion measurement, Measured by the number of hops; Energy is also crucial for optimizing routing protocols during the routing process. Before data forwarding, the energy of each node is considered: a threshold for the remaining energy of a node is defined. During the first route discovery process, a node that receives an RREQ packet checks whether its remaining energy is greater than the corresponding threshold. If it is greater than the threshold, the RREQ packet is forwarded; otherwise, the packet is discarded.

[0022] Route maintenance: In the M-AODV routing algorithm, nodes broadcast HELLO messages at fixed time intervals to detect the connectivity status of links with neighboring nodes. When a node fails to receive a valid response from a neighboring node within a specified time, it can be assumed that the link with that neighbor may have been interrupted. If the link happens to be on the current data forwarding path, the route maintenance process is initiated. For link interruption issues, the protocol prioritizes a local repair mechanism, that is, the upstream node at the break point initiates a new route request to restore communication as much as possible in a local area, reducing the latency and overhead caused by re-initiating the whole network route discovery. If the local repair is successful within the specified time, data transmission continues along the newly established path. If the local repair fails, the relevant node sends a RERR message to the upstream node to notify that the original route has failed, until the source node receives the error message and restarts the route discovery process. The processing procedure of a node after receiving a RERR message is as follows: Figure 2 As shown, a node extracts an unreachable destination address from a received RERR message and checks if a corresponding route entry exists in its local routing table. If not, it continues to extract the next unreachable destination address and makes a judgment; if it exists, it updates the routing information related to that unreachable destination address in its routing table. Subsequently, the node further determines whether the unreachable node information contained in the RERR message needs to be notified to this node; if not, it returns to process the next unreachable destination address; if so, it further determines whether the RERR message needs to be forwarded; if forwarding is required, the node sends a RERR frame to other relevant nodes; if forwarding is not required, the processing ends. Through this mechanism, M-AOD can promptly transmit error information when a link fails and provide support for subsequent route recovery, thereby improving the communication reliability of the network in dynamic environments.

[0023] The self-organizing network reconfiguration algorithm includes fault detection, fault location, reconfiguration strategy, and topology optimization.

[0024] Fault detection is the foundation of refactoring. The algorithm monitors node status in real time by periodically sending "heartbeat" messages between nodes. The time interval for each node to send a "heartbeat" packet is set to... If node At any moment To the node Send a "heartbeat" packet, in No node received at any time The response, and after If no response is received after the second retrieval, then the node is preliminarily determined to be... In the event of a failure, the node continuously monitors the signal strength of its own communication link. and bit error rate To assess link quality, a lower threshold for signal strength is set. The upper limit threshold for the bit error rate is Introducing a link quality evaluation function : when When this occurs, it indicates that the link is at risk of failure. For example, in a large overseas mining EPC project, the strong electromagnetic interference generated by the operation of large equipment at the construction site caused a sharp drop in the signal strength of some links and a significant increase in the bit error rate. This evaluation function can quickly identify potential faults.

[0025] Once a fault is detected, the fault location procedure is immediately initiated. A distributed fault location method is adopted, in which the node that detects the fault broadcasts the fault information to the surrounding nodes. The nodes that receive the fault information make a preliminary judgment on the fault location based on their own stored network topology information and routing table, and then feed back the relevant information to the node that initiated the fault detection. Through the information interaction and comprehensive analysis of multiple nodes, the specific location of the faulty node and link is accurately determined.

[0026] Reconstruction Strategy: After identifying the fault location, when node i fails and leaves the network, all its neighboring nodes can detect the fault immediately and run the algorithm. The computational complexity of the algorithm is mainly related to the degree of the faulty network node. When a large number of network nodes experience communication failures, the topology can be quickly reconstructed. In addition, to further optimize the algorithm's running time, it is mainly based on the breadth-first search (BFS) algorithm to obtain the spanning tree. Its basic idea is to start from the root node, traverse the graph until all nodes in the graph are visited, and finally generate a breadth-first search tree. The time complexity of the algorithm is O(V+E), where V and E represent the number of nodes and the number of edges in the ad hoc network, respectively. The specific algorithm is as follows: Input: The current global adjacency matrix A, and the IDs of the faulty network nodes. The current parent and child node numbers of the node. , k=1,2,... Output: The reconstructed parent node number (NLR) and the newly added child node number. k=1,2,... Step 1: Let = ; Step 2: Based on the current global adjacency matrix and faulty network node number Construct the set of neighbor nodes of the faulty node. ; Step 3: In Remove the faulty node, all edges associated with the faulty node, and the set of nodes excluding its neighbors. All nodes and related edges outside the local boundary are considered to construct a local adjacency matrix containing only adjacent nodes. ; Step 4: Select the set of neighboring nodes The node with the smallest index is selected as the root node, and the local adjacency matrix is ​​calculated based on the BFS algorithm. Spanning tree in ; Step 5: Based on the spanning tree Find the parent and child node numbers after topology reconstruction. , If k=1,2,... and Then update The parent node of the root node is .

[0027] During the reconstruction process, it is necessary to focus on optimizing the network topology and consider the remaining power of the nodes. Communication load Factors that dynamically adjust the connection relationships between nodes can lead to a more balanced distribution of network load. For example, if there are factors in the network... Nodes, Nodes The remaining power is The communication load is The average remaining power of the network is The average communication load is The following objective function is minimized through an optimization algorithm: The formula enables a balanced distribution of network load, improving the overall stability and reliability of the network and extending its lifespan.

[0028] The self-organizing network reconfiguration algorithm has a rigorous and orderly process. First, in the initialization phase, when the emergency communication network starts, each node initializes its own status information, including node ID, location, battery level, and communication capabilities, and broadcasts this information to surrounding nodes to build the initial network topology. Next, in the real-time monitoring phase, nodes monitor the network according to a set time interval. Sending "heartbeat" packets continuously monitors the link status. Upon detecting a fault, the fault location and reconfiguration process is immediately triggered. After reconfiguration, the network is tested and verified to ensure normal communication has been restored. If reconfiguration fails, fault detection and location are repeated to find other feasible reconfiguration solutions. Finally, after normal network communication is restored, real-time monitoring continues to be maintained to respond to any new faults that may arise, ensuring the continuous and stable operation of the network.

[0029] RSA and AES Hybrid Encryption Communication Algorithm: In constructing a long-distance emergency communication network based on a wireless mesh self-organizing network, the design of the communication encryption algorithm is crucial for ensuring secure data transmission, especially in long-distance communication where data transmission paths are long, the number of nodes is large, and communication security risks are higher. Operating in an open wireless environment makes it more susceptible to interference and attacks. To address this issue, this patent employs a hybrid encryption mechanism combining RSA asymmetric and AES symmetric encryption to achieve the following core functions: using the RSA algorithm to ensure secure exchange of session keys and avoid man-in-the-middle attacks; utilizing the AES algorithm for rapid encryption of communication data to meet the high bandwidth requirements of long-distance, multi-line transmissions; and generating an independent key for each session to increase resistance to replay attacks and key cracking. The RSA and AES hybrid encryption communication algorithm includes key generation, key distribution, data encryption and decryption, and encrypted communication processes.

[0030] Key Generation: In complex overseas project environments, secure key generation is the cornerstone of encrypted communication. Each terminal device joining the network needs to generate a pair of RSA asymmetric keys. The public key is used to encrypt data externally and is publicly available across the network, while the private key is securely kept by the device itself and used to decrypt specific information. The generation process is as follows: Choose two large prime numbers and And calculate the modulus Calculate Euler's totient function: Choice and Using coprime integers e as the public key exponent, the private key exponent d is solved using the Extended Euclidean Algorithm, satisfying the following condition: Key distribution: At the start of each communication session, the calling terminal is responsible for generating the communication key. Let the communication key generated by the calling terminal be... The calling terminal obtains the public key of the called terminal. Use the public key to communicate the key Asymmetric encryption can be performed as follows: Where e is the RSA public key exponent of the called terminal, and n is the RSA modulus. The calling terminal transmits the encrypted communication key through a wireless ad hoc network. Send to the called terminal, the called terminal receives Then, use your own private key Decryption is performed using the following formula: d represents the RSA private key index of the called terminal. Through the above process, the called terminal successfully obtains the communication key. This prepares for subsequent data encryption and decryption.

[0031] Data encryption and decryption: When both communicating parties obtain the communication key Subsequently, symmetric encryption technology was adopted to encrypt and decrypt communication data. Among symmetric encryption algorithms, AES is widely used due to its high efficiency and security.

[0032] Let the communication data to be sent be The data is encrypted using the AES encryption algorithm, and the encryption function is expressed as follows: The encrypted ciphertext is The encryption process is as follows: The AES algorithm will transmit plaintext. Divide the data into 128-bit groups and use a key for each group. Under its control, multiple rounds of complex transformations are performed, including byte substitution, row shifting, column obfuscation, and round key addition. Assume the plaintext... Divided into , ,…, If the groups are divided into groups, the encryption process for each group is as follows: The AES encryption function uses the communication key Ks as the key, and the ciphertext is... Depend on , ,…, composition.

[0033] The recipient received the encrypted message Then, use the same communication key. and the corresponding decryption function Decryption is performed, and the decryption process is as follows: Symmetric encryption ensures the confidentiality of communication data during transmission.

[0034] Encrypted communication process: The specific process of encrypted communication is strict and orderly to ensure the security and reliability of communication.

[0035] Step 1: Call Request Initiation. The calling terminal filters the target called terminal from its pre-established trusted terminal registry and initiates a call request to it. This trusted terminal registry contains relevant information about legitimate terminals, used for verification and establishing a secure communication connection; Step 2: Response and Public Key Transmission. Upon receiving the call request, the called terminal immediately responds to the call and simultaneously generates a public key pair according to the key generation rules described above. and private key and the public key Send to the calling terminal; Step 3: Communication Key Encryption and Transmission. The calling terminal randomly generates a communication key for this communication. Then, using the public key sent by the called terminal. right Asymmetric encryption is performed, and the calling terminal transmits the encrypted communication key. Send it to the called terminal via a wireless self-organizing network; Step 4: Communication key decryption. The called terminal receives the encrypted communication key. Then, use your own private key Decryption is performed, and the communication key is obtained through calculation. ; Step 5: Encrypted Data Communication. The calling and called terminals use a shared communication key. The communication data is encrypted and decrypted using symmetric encryption technology, and the sender then transmits the communication data. Encrypt to ciphertext And send encrypted messages via wireless ad hoc network. The recipient receives the encrypted message Then, the original communication data was obtained by decryption, thus realizing encrypted communication.

[0036] Through the aforementioned rigorous communication encryption algorithm process, secure data transmission is achieved in the wireless mesh self-organizing network, effectively preventing unauthorized terminal intrusion and eavesdropping by other users within the network. This strategy, which comprehensively employs asymmetric and symmetric encryption, not only significantly improves the confidentiality and reliability of the entire communication system but also is highly adaptable to long-distance emergency communication networks in large-scale overseas EPC projects, providing strong communication security guarantees for the smooth progress of projects and the efficient implementation of emergency rescue work.

[0037] The above are merely embodiments of the present invention and do not limit the patent scope of the present invention. Any equivalent structural transformations made using the present invention specification, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A long-distance emergency communication network system based on a wireless ad hoc network, characterized in that: This includes a distributed mesh network architecture, the M-AODV wireless ad hoc network routing protocol, ad hoc network reconfiguration algorithms, and a hybrid RSA and AES encrypted communication algorithm. The distributed mesh network architecture is the overall structure of the entire emergency communication network; The M-AODV wireless ad hoc network routing protocol is a path establishment and maintenance mechanism within the network architecture; The self-organizing network reconfiguration algorithm is a fault recovery and topology reconstruction mechanism in the network architecture. The relationship between the reconfiguration algorithm and routing is as follows: routing selects a route on the current topology, while reconfiguration repairs or rebuilds the topology after it is broken. After reconfiguration, the routing protocol continues to select routes and forward based on the new topology. The RSA and AES hybrid encryption communication algorithm is a security mechanism for business data transmission, operating as a security protection layer during the communication process.

2. The long-distance emergency communication network system based on a wireless ad hoc network according to claim 1, characterized in that: The distributed mesh network architecture consists of multiple wireless mesh network terminal nodes with integrated routing capabilities. Long-distance communication between nodes is achieved through multi-hop relays. The network architecture includes the following core components: System Nodes: Each node consists of a control unit and a wireless communication unit. The control unit is responsible for data storage and routing control, while the wireless communication unit is responsible for data transmission and reception. Time synchronization module: Ensures network-wide time synchronization and provides a time reference for multi-hop transmission; Control Center: Responsible for network-wide monitoring and data analysis, and provides a user interface; Power module: Provides stable power support for nodes; some nodes can be equipped with solar renewable energy.

3. The long-distance emergency communication network system based on a wireless ad hoc network according to claim 1, characterized in that: The M-AODV wireless ad hoc network routing protocol includes route discovery and route maintenance; The route discovery process is similar to the traditional AODV, but it takes into account the problems of low remaining energy of nodes causing energy depletion and low received signal strength potentially causing link instability. During the path selection process, thresholds are set for the remaining energy of nodes and the received signal strength to prevent nodes with low energy and paths with low received signal strength (i.e., unstable links) from participating in the route transmission, thereby improving the performance of the routing protocol. When a source node sends a message to a destination node, it first checks its own routing table for a route to the destination. If no route exists, the data packet is stored in the source node's data buffer, and then route discovery is enabled. The difference is that the modified protocol checks the received signal strength of neighboring nodes in the source node's neighbor table before sending the message. If the received signal strength is greater than or equal to a received signal threshold, then it calculates... Its formula is ； in Let be the threshold value of the received signal strength of node j from its neighbor node i. The received signal strength; Calculated The RSSM field is stored in the corresponding location, and then an RREQ route request packet is generated to the neighboring node. When a node receives an RREQ message, it first determines whether to call the function in the route discovery process. If the node is an intermediate node, it first compares the remaining energy of the intermediate node with the energy threshold. If the remaining energy is less than the capacity threshold, the node is discarded. The purpose is to prevent nodes with too low energy from continuing to participate in the forwarding of RREQ packets, which could cause the node to die quickly, leading to network regionalization and the inability to obtain a path to the destination. This would require re-discovering the path, increasing both energy consumption and transmission complexity in the network. If the remaining energy is greater than the capacity threshold, the node will continue to forward data. When receiving RREP route packets, it first determines whether the node is the destination node. If not, it updates the route to the destination node and forwards the data according to the reverse route established during the forwarding RREQ process. If the node is the source node in RREQ, it starts a timing mechanism when it receives the packet for the first time, and saves the congestion level and received signal strength in RREP. Then, it calculates the reliability value of the path according to the path reliability function. When the timing mechanism ends, it selects the path with the highest reliability from among many paths as the optimal path for data transmission. The formula for the path reliability function is as follows: ； in For congestion measurement, Measured by the number of hops; Energy is also crucial for optimizing routing protocols during the routing process. Before data forwarding, the energy of each node is considered: a threshold for the remaining energy of a node is defined. During the first route discovery process, a node that receives an RREQ packet checks whether its remaining energy is greater than the corresponding threshold. If it is greater than the threshold, the RREQ packet is forwarded; otherwise, the packet is discarded.

4. A long-distance emergency communication network system based on a wireless ad hoc network according to claim 3, characterized in that: In the M-AODV routing algorithm, nodes broadcast HELLO messages at fixed time intervals to check the connectivity status of links with neighboring nodes. If a node fails to receive a valid response from a neighboring node within a specified time, it is assumed that the link with that neighbor may have been interrupted. If the link happens to be on the current data forwarding path, the route maintenance process is initiated. For link interruption issues, the protocol prioritizes a local repair mechanism, whereby the upstream node at the break point initiates a new route request to restore communication as much as possible within a local area, reducing the latency and overhead caused by re-initiating the entire network route discovery. If the local repair is successful within the specified time, data transmission continues along the newly established path. If the local repair fails, the relevant node sends a RERR message to the upstream node to notify that the original route has failed, until the source node receives the error message and restarts the route discovery process.

5. A long-distance emergency communication network system based on a wireless ad hoc network according to claim 1, characterized in that: The self-organizing network reconfiguration algorithm includes fault detection, fault location, reconfiguration strategy, and topology optimization.

6. A long-distance emergency communication network system based on a wireless ad hoc network according to claim 5, characterized in that: Fault detection is the foundation of refactoring. The algorithm monitors node status in real time by periodically sending "heartbeat" messages between nodes. The time interval for each node to send a "heartbeat" packet is set to... If node At any moment To the node Send a "heartbeat" packet, in No node received at any time The response, and after If no response is received after the second retrieval, then the node is preliminarily determined to be... In the event of a failure, the node continuously monitors the signal strength of its own communication link. and bit error rate To assess link quality, a lower threshold for signal strength is set. The upper limit threshold for the bit error rate is Introducing a link quality evaluation function : ； when This indicates that there is a risk of failure in the link.

7. A long-distance emergency communication network system based on a wireless ad hoc network according to claim 5, characterized in that: Once a fault is detected, the fault location procedure is immediately initiated. A distributed fault location method is adopted, in which the node that detects the fault broadcasts the fault information to the surrounding nodes. The nodes that receive the fault information make a preliminary judgment on the fault location based on their own stored network topology information and routing table, and then feed back the relevant information to the node that initiated the fault detection. Through the information interaction and comprehensive analysis of multiple nodes, the specific location of the faulty node and link is accurately determined.

8. A long-distance emergency communication network system based on a wireless ad hoc network according to claim 5, characterized in that, Its features are: Reconstruction Strategy: After identifying the fault location, when node i fails and leaves the network, all its neighboring nodes can detect the fault immediately and run the algorithm. The computational complexity of the algorithm is mainly related to the degree of the faulty network node. When a large number of network nodes experience communication failures, the topology can be quickly reconstructed. In addition, to further optimize the algorithm's running time, the breadth-first search algorithm is mainly used to obtain the spanning tree. Its basic idea is to start from the root node, traverse the graph until all nodes in the graph are visited, and finally generate a breadth-first search tree. The time complexity of the algorithm is O(V+E), where V and E represent the number of nodes and the number of edges in the ad hoc network, respectively. The specific algorithm is as follows: Input: The current global adjacency matrix A, and the IDs of the faulty network nodes. The current parent and child node numbers of the node. , k=1,2,... Output: The reconstructed parent node number (NLR) and the newly added child node number. k=1,2,... Step 1: Let = ; Step 2: Based on the current global adjacency matrix and faulty network node number Construct the set of neighbor nodes of the faulty node. ; Step 3: In Remove the faulty node, all edges associated with the faulty node, and the set of nodes excluding its neighbors. All nodes and related edges outside the local boundary are considered to construct a local adjacency matrix containing only adjacent nodes. ; Step 4: Select the set of neighboring nodes The node with the smallest index is selected as the root node, and the local adjacency matrix is ​​calculated using the BFS algorithm. Spanning tree in ; Step 5: Based on the spanning tree Find the parent and child node numbers after topology reconstruction. , If k=1,2,... and Then update The parent node of the root node is .

9. A long-distance emergency communication network system based on a wireless ad hoc network according to claim 5, characterized in that: During the reconstruction process, it is necessary to focus on optimizing the network topology and taking into account the remaining power of the nodes. Communication load Factors that dynamically adjust the connection relationships between nodes can lead to a more balanced distribution of network load. For example, if there are factors in the network... Nodes, Nodes The remaining power is The communication load is The average remaining power of the network is The average communication load is The following objective function is minimized through an optimization algorithm: ； The formula enables a balanced distribution of network load, improving the overall stability and reliability of the network and extending its lifespan.

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