# Towards an Efficient Method for Large-Scale Wi-SUN-Enabled AMI Network Planning
## 2 Smart Grid Network Architecture
### Network Planning Constraints  
The constraints presented in this section are based on directives for the implementation and operation of the smart grid of a large electric power company in the state of Parana, in southern Brazil. The constraint list includes:  
* The smart grid structure comprises two wireless networks (Figure 1b): the Backhaul network and the AMI wireless network based on Wi-SUN technology. In addition, the backhaul network is connected to an optical network (WAN backbone) at electric substations. * The wireless backhaul network is segmented into three virtual local area networks (VLANs) with different traffic priorities. The first VLAN is for radio monitoring and has the highest priority. The second VLAN is for the equipment automation of the distribution power network and has the second highest priority. Finally, the third VLAN is for the AMI communication traffic. This VLAN transports smart metering data traffic from the Wi-SUN network and has the lowest priority. The AMI and DA communication networks are separated by VLANs at each running point with the physical network (substation, VHF stations, or branch) as this increases the security level of the communication network as a whole. * The main elements of interest in the AMI network topology for this research include (i) smart meters, which measure energy consumption; (ii) AMI routers, with which the meters connect and which are responsible for forwarding messages through the network; and (iii) AMI gateways that accept connections from routers as well as direct connections from meters and that, in addition to relaying messages, serves as a communication interface between the AMI network and the Backhaul network. * Regarding the Backhaul network, the elements of interest for this study include the Backhaul Routers, with which the DA devices are connected and which also allow the connection of AMI gateways, and the Backhaul Gateway, which interfaces between the Backhaul network and WAN network for forwarding messages to/from the control center. In this study, when referring to routers and gateways, we are referring in a simplified way to AMI Routers and AMI Gateways. * The automation and metering communication network infrastructure are based on the existence of poles, as it occurs in many companies worldwide. The advantage of using the poles is based on the fact that they are part of the company's asset list,  
Figure 1: Smart grid scenario. (**a**) Overview of a smart grid scenario, highlighting the main elements in the NAN and WAN regions considered in this research. (**b**) Diagram of Backhaul and AMI network traffic flows to demonstrate the main elements in transferring information between endpoint devices and the control center. minimizing the need to contract third-party infrastructure. In addition, poles offer the supply voltage necessary for the setup and operation of the communication devices and present a favorable height for the positioning of the routers and gateway devices. * DAs are installed on poles and mainly in the overhead power network. Underground power networks are restricted to small areas in Brazil, in some urban centers, and they are treated as an exception (not in the scope of this study). Communication with DA equipment uses distributed network protocol (DNP3) over an IP using pooling and not unsolicited messages due to a limitation of the supervisory control and data acquisition (SCADA) monitoring system. * The management of the information flow from the endpoints to the control center considers that data from the AMI elements (e.g., smart meters) and the DAs will share the physical infrastructure of the Backhaul network.