## 5 Integrated IoT Architectures in Smart Grid  
Several IoT architectures have been proposed to be integrated into SG. They can be categorized to architectures with three layers or four layers [48; 49; 50; 51; 52; 53] (see Table 1). In [48], three layers are proposed. Layer 1 includes smart meters, network devices, and communication protocols. Layer 2 contains devices which are responsible for receiving data at the central system. Layer 3 includes artificial intelligent systems to provide information to decision and billing systems. \begin{table}
\begin{tabular}{c c c c c} \hline \hline  & [48; 50] & [51] & [52] & [53] \\ \hline Layer 4 & & Application & Social & Master station system \\ Layer 3 & Application & Cloud management & Application & Remote communication \\ Layer 2 & Network & Network & Network & Field network \\ Layer 1 & Perception & Perception & Perception & Terminal \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Three-layer and four-layer models which are proposed for IoT architecture in a smart grid. In [49; 50], a three-layer structure is presented that contains perception layer, network layer, and application layer. Perception layer (or device layer) uses different kinds of sensors (e.g., power sensor), tags and readers (e.g., RFID tags/readers), or sensor equipment (such as GPS devices or cameras) to collect information. The network layer contains different kinds of wired and wireless industry-specific or public communication networks (such as 2G, 3G, 4G, cable broadband, public switched telephone networks, private networks, Wi-Fi, ZigBee) and the Internet to map the information gathered by sensors in the perception layer to communication protocols. It is used to route and transmit these mapped data to the application layer for processing, control, and access to the core network. It includes management and information centers. The application layer processes the information received from the network layer to monitor IoT devices in real time. It uses a variety of IoT technologies to realize an extensive set of IoT applications and contains application structure. Application structure is responsible for information processing and computing, and interface to resources. IoT can accomplish the integration of information technologies via the application layer. In [51], the authors proposed four layers: device layer, network layer, cloud management layer, and application layer. Device layer contains two sub-layers: (1) thing layer (which contains different types of sensors, smart meters, smart tags, and actuators) to sense environment, collect data, and control home appliances, (2) gateway layer (which contains microcontrollers, communication modules, and local display and storage) that controls how to connect to elements of thing layer. The network layer sends the data from the device layer to the application layer. The cloud management layer is responsible for data storage and analysis and data and user management. The application layer provides services to end users such as homeowners or utilities and includes demand response management, dynamic pricing, or energy management. The authors in [52] reviewed previous three-layer and four-layer models. The 4 th layer in the four-layer model is the supporting layer which integrates some common IoT technologies. Then, they proposed a four-layer model that includes the previous three layers (perception layer, network layer, and application layer) and add an additional social layer on top of these three layers. The social layer regulates IoT applications. The proposed four-layer model in [53] has a terminal layer, field network layer, remote communication layer, and master station system layer. The terminal layer comprises remote terminal units, smart meters, and smart devices. The field network layer includes wired communications such as fiber optics or wireless communication technologies such as Wi-Fi, ZigBee, or RFID. The remote communication layer contains wired and wireless wide area networks such as 3G or 4G wireless cellular networks.