## 5 The Application  
To widely test the idea, an isle of lamp posts, as shown in Figure 2, has been designed and realized. \begin{table}
\begin{tabular}{c c c c c c} \hline  & **WiMAX** & **ADSL** & **WiFi** & **3G** &
\begin{tabular}{c} **Satellite** \\ **Communication** \\ \end{tabular} \\ \hline Wireless? & Yes & No & Yes & Yes & Yes \\ Distance & Up to 70 km from & Everywhere & Up to 100 m & Up to 5 km from & Everywhere the \\ Covered & the CPE & with cable & & the BS & signal satellite is on \\ Subscription & & About 20 € & About 20 € & About 20 € & About 100 € \\ Costs & & & & & \\ Availability & Medium/High & No & No & Medium & Yes \\ in rural area & & & & & \\ \hline \end{tabular}
\end{table} 
Table 3: WiMAX _vs._ other communication technologies. Through a flowchart, Figure 3 shows the management strategy of the isle. The electronic card checks if the sunlight is lower than a fixed limit [3]; in this case, it waits until the sensors signal the presence of a car or a pedestrian. When this happens, the control unit switches on the light for a fixed time, the current sensor starts the measurements and, in case of a fault detection, an alarm is sent to the master lamp. If no fault is detected, the microcontroller stores the current values. During the night the Coordinator Lamp Post requests data from the secondary lamp posts and makes them available on the Internet. In the case of people in difficulty, which need light for their activities, they will be able to switch on the lights by pressing one of the emergency buttons located in specific locations at the crossroad. The electronic card, also called monitoring station, is used in two versions:  
Figure 3: Management strategy of the Smart Grid. Figure 2: Schematic image of the on street system. the first detects the presence of a vehicle and is called Presence Sensor Electronic Card, while the second manages the lamp post and is called Monitoring Station for Lamp Posts. The first are placed near the road at about 45 m from the crossroad. They are enabled when the sunlight is lower than a fixed limit. They read a photoelectric sensor and if its light beam is interrupted by the passage of a car, the control card sends a wireless signal to the isle of lamp posts by the ZigBee network. When this signal is received by the Monitoring Stations for Lamp Posts and it are equipped with a ZigBee Tx/Rx, they switch on the light. The monitoring station is realized with the use of a PIC 16 f 688 microcontroller that also manages the wireless transmissions. The lamp post management is thus realized, but for intelligent management, the maintenance needs require a wider and deeper control of the lamp posts. To meet these requests, a current sensor, directly mounted on the lamp posts and read by the Monitoring Station, provides information about lamp post activity and power consumption. This information is stored in the PIC memory and, if requested by the next layer, is sent to it. The second layer communicates with the first layer by the ZigBee network and collects data coming from each lamp post. The collected data are then available for the analysis of power consumption and for monitoring the lamp activity. Obviously, if the n-lamp post does not communicate or sends wrong data, this layer will send an intervention request toward a remote operator to solve the problem. The second layer uses a RaspBerry-Pi card [24, 25, 26, 27]. This is placed only in a lamp post called Coordinator, (another lamp post equipped with the RaspBerry-Pi may cause redundancy) and it is connected to the lamp post Monitoring Station. The latter makes possible the communication between the RaspBerry-Pi and the other lamp posts realizing the communication between the second and the first layer. The RaspBerry-Pi plays a role of webserver collecting data from each lamp post and displaying them. The third layer uses the RaspBerry-Pi to send these data to the World Wide Web. A graphical interface (Figure 4) shows the information on the lamp posts' activities.