## 3 Key Technology of the A2S Integrated MIoT
### Cloud/Edge Computing and Caching  
#### 3.2.1 Mobile Edge Computing (MEC)  
In the A2S integrated scenario, several organizations and entities are currently using MEC for different applications. China Mobile Communications Group, one of the major mobile communication operators in China, is actively exploring and applying the MEC technique in A2S integrated systems [115]. They use MEC to push computing resources and services to the edge of the network to meet users' demands for low latency and high throughput. For example, with MEC support, they provide intelligent traffic management systems that enable the intelligent traffic monitoring and optimization through real-time data processing and decision-making on edge servers. Ullens Group, a German technology company, has carried out a research project using the MEC technique in A2S integrated systems [116]. They have combined MEC with the UAV technology to achieve the real-time image processing and analysis of drones. By carrying out image recognition and target tracking on edge computing nodes, they can achieve the intelligent navigation, target detection and capture of UAVs, further supporting A2S integrated applications. The FCC also recognizes the potential of MEC in the A2S integrated scenario and supports related research and pilot projects [117]. They encourage operators and technology providers to leverage MEC to push computing and storage capabilities to the edge of the network, enabling applications such as smart cities, IoT, and virtual reality. These measures are de signed to enhance the performance and user experience of wireless networks and promote the development of A2S integrated systems. As one of the major mobile operators in Japan, NTT DOCOMO is also applying the MEC technique in A2S integrated systems. They use MEC to place computing and storage resources at the edge of the network, supporting diverse application scenarios including intelligent transportation, intelligent healthcare, and industrial automation. By processing data and making decisions at edge nodes, they can provide services with low latency and high reliability [118]. Figure 5 shows an MEC architecture in the A2S integrated MIoT. Specifically, the three-tier architecture of edge computing in the A2S integrated MIoT includes the cloud computing layer, the mobile edge layer, and the device edge layer [5; 102]. The cloud computing layer enhances the response speed and reduces latency by deploying data processing functions closer to the cloud. The mobile edge layer emphasizes executing edge computing on mobile devices to alleviate the central cloud's burden, adapting to dynamic environments. The device edge layer extends computing capabilities to IoT devices, enabling localized data processing, reducing reliance on the network, and enhancing system stability and efficiency. 1. Edge device layer: This is the lowest level and it includes the various physical devices and sensors deployed at sea. These are responsible for collecting data on the marine environment, controlling offshore equipment, and obtaining other relevant information. These devices are typically low-power and have limited computing and storage capabilities. Their main task is to transmit the collected data to the edge node through the wireless network [119]. 2. Mobile edge layer: This layer is located between the edge device layer and the cloud computing layer; it deploys the computing and storage resources at the edge. Mobile edge nodes are similar to the IoT gateways in that they can be placed close to offshore equipment and sensors to provide low-latency computing and storage capabilities [120]. These nodes can be UAVs, floating nodes, or ship-based nodes, among others. The main task of the mobile edge layer is to carry out local data processing, analysis, and storage after receiving the data from edge devices. 3. Cloud computing layer: This is the highest layer, usually located on a remote data center or cloud server. The cloud computing layer provides more powerful computing  
Figure 5: MEC architecture diagram.