2.1. Network Transmission under a Rainstorm in Henan Province

On the afternoon of July 20, 2021, a video of the Henan subway flooded due to a rainstorm spread all over the network. Suddenly, the Internet and traditional media have spoken out, and the Henan local flood affected netizens’ hearts all over the country. News of Henan’s torrential rain quickly spread across the Internet. Figure 1 displays the major accident scenes caused by the rainstorm in Henan.

As shown in Figure 1, due to the rainstorm, people in Henan are affected to varying degrees in all aspects, among which road traffic and network operation are the most serious. Contemporary network operation is exceptionally vital, and network operation needs to rely on essential network equipment and network base stations. When natural disasters occur, unpredictable damage will be caused to network equipment and base stations. Therefore, it is a considerable problem to restore the network operator when the network equipment and base station are damaged. How to overcome and improve this problem has become epoch-making research. The rescue work under natural disasters and disaster investigation requiring signal communication must be improved. Therefore, the communication mode of small equipment such as UAV has become the leading technical means of communication under natural disasters.

2.2. Wireless Signal Transmission Model via Network Coding

The remote communication of UVA network is the inevitable development trend. Effective and reliable real-time communication between UAVs is the premise and foundation of realizing their cooperative operation. Because the information transmission technology via blockchain has the advantages of good security and timeliness, low system complexity, and low power consumption, it is an excellent choice to apply it to UAV communication links [8]. Network coding and intermediate coding node can realize the efficient transmission of information data through the received data’s nonlinear or linear coding operation. Network coding technology was first used in a wired ne, specifically used to optimize the network layer to improve the running speed of wired networks [9]. Nowadays, this technology has matured, but wireless network coding technology still faces many problems, including the issues of wireless network coding itself and the difficulties in customer use [10]. From the analysis of the factors of network coding, network coding significantly improves the network data transmission performance and network throughput, saves network bandwidth resources, balances the network load, and has many defects. From an internal point of view, network coding significantly improves network data transmission performance and network throughput, saves network bandwidth resources, balances network load, and has many defects. Compared with traditional network data transmission, nodes in a network coding system need to operate coding and decoding programs frequently, which will produce a series of problems. For example, complex programs will increase the delay of network data transmission and consume excessive network computing resources [11]. Therefore, in the process of network coding optimization, the network coding program needs to be optimized first.

Principally, network coding transmission information is realized by defining network nodes, determining the relationship between output points and input points, and then, encoding the required data based on the intermediate nodes with coding conditions. The network coding system includes many intermediate nodes encoding in turn. After the previous node completes the required coding content, it will transmit the data to the next node. When all intermediate nodes complete coding the data they need, the network coding system will dispatch the coded output to the destination node to complete the data transmission [12]. When the destination node receives the data sent by the original source node, it will decode the data to obtain the original information [13]. Figure 2 reveals the basic flow of data transmission through network coding.

As shown in Figure 2, data transmission between users is implemented after determining the transmitted data’s source node and destination node. The user only needs to upload and view the corresponding data during data transmission. The encoding and decoding programs are completed at the wireless network end, significantly saving the user’s resources [14]. During data transmission, the number of intermediate nodes is at least 2. The coding function of nodes is obtained under certain conditions, indicating that not all nodes can be coded. Theoretically, when the generation domain of the network coding system is infinite, applying network coding can also realize the multidial theoretical capacity. At present, the limited generation domain is still used in practical applications [15]. Network coding can carry out nonlinear and linear processing in the process of data processing. In theory, linear network coding can implement the maximum capacity of network information transmission. In the encoding process, the coefficients used for encoding are selected according to the size of the generation domain. The selection of encoding coefficients needs to meet the encoding task of each intermediate node to ensure that the destination node that finally receives the data can decode smoothly [16].

2.3. Blockchain Technology

As network technology advances, the network should meet the high-speed data transmission and the security guarantee in the process of network transmission [17]. Therefore, the role of blockchain technology is self-evident. Blockchain is composed of nodes. Its task is to store, encrypt, and package data to generate a new block. Then, a representative node in the block is selected and connected with other blocks to form a blockchain chain [18]. Blockchain is a database consisting of decentralized, centralized structures and encrypts data. Its primary function is to ensure that data is not stolen or modified. Compared with traditional databases, blockchain databases have the advantages of decentralization, tamper-proof, anonymization, time sequence, centralized maintenance, and programmability [19]. Decentralization of blockchain means that the blockchain nodes have the same functions and powers in a multinode network structure. Tamper-proof means that in the blockchain, except for creating blocks, other blocks have the unique hash value of the previous block’s data, and all blocks are connected through the hash value. If the block’s data is modified, the hash value in the block will change accordingly. At this time, when the hash value of the previous block disappears, the blockchain connection will be forced to be disconnected, so other blocks will organize the block’s data to be modified [20]. Anonymization means that the blockchain system will hide the user’s information during data transmission between users for user security. When users conduct data transactions, they contact each other through addresses [21]. Time sequence means that each blockchain has a time tag. The blockchain will store the data in order according to the time tag of the node. It can also quickly find the data according to the time tag of the data in practice [22]. Centralized maintenance indicates that the blockchain solves the problems in the blockchain system through various algorithms to maintain the system’s regular operation [23]. Programmability demonstrates that the blockchain can calculate the data through the code with contractual nature and save the results in the public database to realize the transformation of multiple data [24]. Figure 3 displays the basic structure of the blockchain.

In Figure 3, the blockchain is composed of multiple blocks. The block is mainly constituted of a block header and a block body. The primary function of the block body is to identify and authenticate users in the transaction process, and the block header is responsible for storing data and including the identification and time tag of the data. The blockchain depends on the parameters in the block header to search for data.

2.4. Data Transmission Algorithm Based on Network Coding

The data transmission based on network coding is carried out through coding and decoding. When the transmitted data is large, the network coding system divides the data into many transmission groups. A group of information is divided into many blocks for coding and transmission in the coding process. Each data coding area contains a data block and other identification areas, covering the storage area of coding coefficients for easy decoding and identification marks, such as generation coding [25]. Figure 4 illustrates the specific structure of network coding for data transmission.

2.5. Model Design Based on Network Coding and Blockchain Technology

Network coding technology is data grouping and block coding transmission of grouped data. Users upload data through wireless networks using mobile devices. After data uploading, the network coding system first groups the data, divides the data randomly, completes the grouped data, and divides the data blocks according to the random principle. Then, the data is encoded and transmitted. The required data is encoded according to different nodes in the transmission process. The encoded data is distinguished by substitute coding and coding coefficients. After all the data are encoded, they are combined with substitute coding as the identification. The combined output coding needs to decode the data. The data is decrypted according to the decoding process’s generation coding and coding coefficients. The generation coding identifies the data; the coding coefficient helps the encoded data recover to the source data [27]. Figure 5 illustrates the flow of data encoding, transmission, and decoding.

As shown in Figure 5, the encoding and decoding process also includes data transactions. The transaction area is in the coding body of the coding block. In other words, the user carries out specific transaction transmission of the data through the coding body. The encoded content of the data is included in the coding terminal. In this way, the actual content of the data is hidden to a certain extent to protect the data. However, its protection mechanism is still imperfect. Therefore, this paper combines network coding with blockchain technology to protect the safe transaction of data in data transmission. Specifically, an efficient and secure wireless signal transmission technology is obtained through network coding technology’s efficient data transmission function and the high-intensity data protection function of blockchain technology. This technology can encrypt data, enhancing the efficiency and reliability of data transmission. Figure 6 shows the specific data transmission through network coding and blockchain technology.

As shown in Figure 6, network coding technology is the fastest form of data transmission at present, but it belongs to a mechanism without data encryption protection. Therefore, in the event of a natural disaster, the network fluctuates, which will result in data loss. Moreover, the data without encryption protection will become transparent data after losing, which is incredibly dangerous for transmitting data. In short, while efficiently transmitting data, it is essential to avoid data loss and data theft under the influence of natural disasters. Here, network coding and blockchain are integrated into data transmission to realize the encryption protection of wireless signals and improve the reliability of wireless signal transmission. Figure 7 provides data transmission after combining network coding and blockchain technology.

According to Figure 7, the user first encodes and transmits the data. Finally, password authentication is essential for data decoding due to the encryption nature of the blockchain to encrypt the data while improving the efficient transmission of data. The studied specific scenario aims to simulate the data transmission effect under the natural disaster scenario. The specific experimental content includes the comparison of the data transmission effect. The total amount of data transmission is 10 G, and the same equipment is used for comparison under different methods.

3.1. Basic Performance Study

Under the same network environment and external flow conditions, the actual data transmission rate of traditional network coding technology, blockchain technology, and the combination of network coding and blockchain technology is compared with the ideal wireless data transmission rate. Figure 8 displays the comparison results of data transmission rates.

In Figure 8, AB represents the actual result of blockchain, IB refers to the ideal result of blockchain, AN means the actual result of network coding, IN stands for the perfect result of network coding, ABN signifies the actual result of network coding combined with blockchain, and IBN represents the ideal result of network coding combined with blockchain. The difference between the perfect and actual results is insignificant in the overall transmission rate comparison, and the maximum difference is 2. The wireless data transmission results of blockchain and network coding differ significantly, with a maximum difference of about 10. However, the wireless data transmission rate difference between the ideal result and actual result of the combination of network coding and blockchain reported here is small, with a maximum difference of about 1.5. Therefore, the wireless data transmission model combining network coding and blockchain can fully meet the o wireless data transmission rate. It is also necessary to make statistics on the specific network resources occupied during the operation of the model. In the current process of wireless data transmission, in addition to the wireless data transmission rate, users pay more attention to the resource occupancy rate. The smaller the resource occupancy rate, the simpler the equipment users need to use. Therefore, reducing the resource occupancy rate in wireless data transmission is necessary.

According to Figure 9, the gap between the overall ideal resource occupancy rate and the actual resource occupancy rate is slight, with a maximum difference of about 2.5%. The resource occupancy rate of network coding is much lower than that of blockchain, with a maximum difference of about 30%. However, there is little difference in the resource occupancy rate in the wireless data transmission process of the combination of network coding and blockchain. The wireless data transmission resource occupancy rate of the combination of network coding and blockchain is about 3% higher than that of network coding. This proves that the resource occupancy rate of the actual model constructed here is in an ideal state.

3.2. Wireless Data Transmission under Natural Disasters

Natural disasters are inevitable. Small natural disasters are bearable for any wireless data transmission without damaging the wireless network base station because they do not cause severe data damage or loss. However, terrible natural disasters have a crippling impact on wireless data transmission. Therefore, a reliable data protection mechanism is needed to avoid significant data loss and data theft after natural disasters in wireless data transmission. Figure 10 summarizes each model’s successful data transmission rate in the process of wireless data transmission under the condition of irregular network fluctuation.

As shown in Figure 10, under the condition of network fluctuation, the successful data transmission rate of the three models is relatively low, up to about 70%. Nevertheless, there is little change in the successful data transmission rate of the model combining network coding and blockchain, all about 70%. Thus, the wireless data transmission model combining network coding and blockchain in natural disasters still shows an ideal data transmission effect. Furthermore, the security of data transmission is investigated. Figure 11 provides the data failure caused by the irregular fluctuation of network data transmission in the case of natural disaster simulation.

Figure 11 presents the data failure rate after tampering or embezzlement of data under the simulated natural disaster. This test simulates ten data transmissions and conducts manual tampering and embezzlement after the data transmission is completed to check the data failure rate after the experiment. The higher the failure rate, the greater the protection degree of the data transmission model to the transmitted data. The results suggest that the failure rate of the network encoded data transmission model after data is tampered with is the lowest, with the maximal rate of about 50%. It can be concluded that the protection degree of the network encoded data transmission model for data is too low to meet the general data transmission needs of users. However, after the data is medicated by blockchain technology, the failure rate of data generally reaches more than 90%. In contrast, the wireless data transmission model based on network coding technology and blockchain generally has a data failure rate of more than 90% after tampering and embezzlement after data transmission. Hence, this model can meet the security needs of users for data transmission.