# Communication Technologies for Smart Grid: A Comprehensive Survey
## 3 Smart Grid Communication
### Communication Network Structure  
A defined communications framework is necessary in this infrastructure. It is crucial to have clearly defined standards to ensure reliable, efficient and secure communication throughout the system [54]. The different network types in the communications layer mentioned above have all different requirements when it comes to data rate and coverage distance, and the chosen communication technology must support these specific requirements, which are summarized in Figure 3 and Table 5. The networks utilize different technologies for communication, both wireless and wired. The premise network (HAN, NAN, or IAN) is closest to the end-user, and enables information and communication flow between home appliances or for example heating, ventilation, and air conditioning (HVAC) systems within the end-user premise. Multiple HANs connects to a NAN. The NAN collects information, and enables communication to the WAN. An illustration of different networks in an SG are depicted in Figure 4. The WAN handles communication of metering information from the end-user to the utilities companies [55]. \begin{table}
\begin{tabular}{l l l l} \hline
**Smart Grid Application** & **Data Rate** & **Latency** & **Reliability** \\ \hline Smart Metering & Low & High & Medium \\ SCADA & Medium & Low & High \\ Substation Automation & Low & Low & High \\ DER & Medium & Low & High \\ DR & Low & Low & High \\ \hline \end{tabular}
\end{table} 
Table 4: Smart Grid QoS requirements [50]. Figure 4: Networks in SG. \begin{table}
\begin{tabular}{p{113.8 pt} p{113.8 pt} p{113.8 pt} p{113.8 pt} p{113.8 pt}} \hline \hline
**Network Type** & **Coverage** & **Data Rate Requirements** & **Data Rate** & **Technology Alternatives** \\ \hline \multirow{4}{*}{WAN} & \multirow{4}{*}{10–100 km} & High data rate. & \multirow{4}{*}{10 Mbps routers and switches} & \multirow{4}{*}{10 Mbps switches.} & Wireless: WiMAX, 3G,4G,5G. \\  & & Devices such as routers and switches. & \(-\)1 Gbps & Wired: Ethernet, Fiber Optic \\ \cline{1-1}  & & Highly dependent on node density and topology. & \(100\) kbps & WiMAX, Cellular. \\ \cline{1-1}  & & Dependent on application. & \(-\)10 Mbps & Wired: Power Line Communication \\ \cline{1-1}  & & Dependent on application. & \multirow{4}{*}{10–100 kbps} & Wireless: ZigBee, Z-wave, Wi-Fi. \\ \cline{1-1}  & & Generally low data rate required. & \multirow{4}{*}{10–100 kbps} & Wi-Fi. \\ \cline{1-1}  & & & & \\ \cline{1-1} \cline{4-4} \cline{5-5}  & & & & \\ \hline \hline \end{tabular}
\end{table} 
Table 5: Overview of network types and requirements [20]. Figure 3: Data rate and communication range requirements in SG hierarchy [20]. Wide Area Network  
A WAN forms the backbone of the communication network in the power grid. It connects smaller distributed networks such as transmission substations, control systems and protection equipment, e.g., Supervisory Control and Data Acquisition (SCADA), Remote Terminal Unit (RTU), and Phasor Measurement Unit (PMU) to the utility companies' control centers [20; 56]. Other terms used for the WAN is the backbone network or Metropolitan Area Network [20]. WAN applications require a higher number of data points at high data rates (10 Mbps-1 Gbps), and long-distance coverage (10-100 km). Real-time measurements are taken throughout the power grid by measurement and control devices and sent to control centers. In reverse, instructions and commands are sent from control centers to the devices [56]. This communication requires both a high degree of distance coverage and speed to maintain stability. Suitable communication technologies for this application are PLC, fiber optic communication, cellular, or WiMAX. Satellite communication can be used as backup communication or in remote locations [20; 57]. **Neighborhood Area Network/Field Area Network:**  
The Neighborhood Area Network (NAN) and Field Area Network (FAN) are networks within the distribution domain, both enable the flow of information between WAN and a Premise Area Network (HAN, BAN, IAN).