## 3 Key Technology of the A2S Integrated MIoT
### Resource Allocation
#### 3.1.1 D2D Technique  
The D2D technique in the MIoT refers to the ability to communicate and exchange information directly between marine devices and sensors, and its model is shown in Figure 3. The D2D technique allows point-to-point communication among devices without a central server, improving the efficiency and reliability of communications [99].  
Figure 2: A2S integrated MIoT architecture.  
In the maritime environment, the D2D technique has many advantages. First, D2D communication can provide faster response times because devices can communicate directly via short-range communication, reducing the latency required to pass through a central node in the traditional way. Secondly, the D2D technique can reduce the probability of network congestion and reduce the delay of information transmission. In addition, D2D communications can also enhance the reliability and stability among devices, as devices can cooperate with each other to maintain communication in the event of unstable network connections. As data in D2D communications in 5G networks are transmitted through connected devices, new possibilities for potential security breaches (such as data hacking) increase [100]. This implies a violation of privacy and confidentiality, and attacks can be classified according to access control, accessibility, authenticity, confidentiality, and integrity. Detailed security threat issues for D2D are given in Table 3.  
In the MIoT, the D2D technique is widely used. China Mobile uses the D2D technique to launch the \"HeWO network\" service, enabling users to share information and resources through the direct communication among mobile phones, file transfer, and other ways; Mazda uses the D2D technique to establish a communication network among vehicles in a vehicle ad hoc network, and realizes real-time data exchange and traffic information sharing among vehicles in the intelligent transportation system. Various emergency relief agencies are also leveraging the D2D technique to enhance disaster management and relief efforts, such as using D2D communication equipment to set up temporary communication networks during disasters to facilitate rapid information sharing and collaborative action. IoT devices can be interconnected through the D2D technique, for  
Figure 3: D2D model.  
\begin{table}
\begin{tabular}{c c} \hline \hline
**Security Threat** & **Specific Situation** \\ \hline \multirow{2}{*}{Eavesdropping} & Through eavesdropping and recording data, private data can be obtained. \\ \hline \multirow{2}{*}{Man-in-the-middle attack} & The attacker secretly takes control of the communication channel, intercepts the message from the sender, modifies it, and forwards it to the recipient. \\ \hline \multirow{2}{*}{Private viewing} & During the device monitoring phase, attackers use verified anonymous identities for malicious activities. \\ \hline \multirow{2}{*}{Disturb} & An attack that interferes with operations, shuts down D2D, and disables the communication itself. \\ \hline \multirow{2}{*}{Inference attack} & Through peers, logical analysis to obtain private information. \\ \hline \hline \end{tabular}
\end{table}
Table 3: Detailed security threat issues for D2D.  
example, for directing communication and intelligent control among devices in the field of smart homes [27; 44; 101; 102]. In the fisheries industry, the D2D technique allows the sensor on the fishing boat to directly communicate with nearby fishing nets, fishing gear, and other equipment, enabling the real-time monitoring of fishing conditions and sea conditions. In the shipping industry, ships communicate directly with port facilities and other vessels through the D2D technique, improving the efficiency and safety of collaborative operations. In summary, the D2D technique plays an important role in the MIoT by providing fast, reliable, and efficient direct communication capabilities among devices, bringing innovation and convenience to the marine industry by enabling the seamless connectivity and information exchange [103].