**4. Control and monitoring application**

344 Energy Efficiency – The Innovative Ways for Smart Energy, the Future Towards Modern Utilities

relation to the sink node.

**Figure 3.** Typical WSN simplified architecture

Convergent traffic:

Divergent traffic:

requirements, subdivided in convergent and divergent traffic.

• Actuate the nodes luminosity (activation, dimerization, etc);

estimation, and lamp lifetime estimation).

estimation, and lamp lifetime estimation, etc).

Figure 3 represents the two types of package traffic, differing by the communication flow in

In order to control and monitor public lighting systems, which is the goal of this work, the following message types based on RFC 5548 are needed, according to the mentioned

• Message to notify the system about failures (which can occur on a lamp, hardware, etc); • Message to update the system about status (on/off) and other information. Periodicity is a maximum of one message per hour, and each node has its own cycle or clock; • Message to notify the system that some neighboring node is out of radio range;

• Specific diagnostic response (battery power, LEDs luminosity level, battery lifetime

• Specific diagnostic request (battery power, LEDs luminosity level, battery lifetime

The proposed architecture is based on the cell model. The cell should provide access to supervision and control of a number of sensor nodes for the management applications. By definition, the sensor node is the device coupled to the lighting point, which is able to communicate via a wireless network.

A cell is composed by a compartment, an industrial computer, a GPS antenna, a communication controller, and sensor nodes. Numerous cells can be formed to completely cover an urban center.

The industrial computer is installed inside the compartment and it is connected to a communication controller, communicating via a serial protocol, while the communication controller communicates to the sensor nodes via wireless network.

The GPS (Global Positioning System) antenna is considered the only time basis among several cells, and then alarms that occurred in different cells can be ordered. Management applications (Configuration/Topology, remote operation server and monitoring) are installed on the Operation computer and they communicate to the cells via Ethernet network.

Remote access is done through an Internet browser from the remote operation application computer to the remote operation server. The Google Maps library (GOOGLE MAPS FAMILY, 2011) is used to plot the lighting points on the maps (Figure 4).

**Figure 4.** Screen obtained with Google Maps library

Figure 5 shows the system architecture and illustrates cell 01, which is responsible for grouping some sensors, and also shows the capability of adding new cells until all lighting points from the city are mapped.

Street Lighting System Based on Wireless Sensor Networks 347

RFC 5548 (2009), the protocol from this standard must operate on a mesh-type topology, so that the devices communicate in multiple hops, based on the low range communication (around 100 meters) with distributed routing to transmit information to their final

However, the large number of nodes and the peculiar nature of operation of wireless sensors urban networks require the project of routing and medium access control (MAC)

Protocols that use only global disseminations to communicate, through broadcast messages (known as flooding protocols), may cause high package traffic, which can lead to a high number of collisions and, thus, reduce the delivery rate. In addition, they demand high

On the other hand, *unicast* protocols should be stateless, which means that packages cannot store information about the route taken to avoid loops or package delivering problems. This is due to a limitation of information that the package of lower layers from the IEEE 802.15.4 standard has. Moreover, protocols must considerer the minimum energy consumption and a

The public lighting concessionaire has the geodesic coordinates of the lighting points in their digital maps, which help in the structure management and maintenance. The routing

Furthermore, devices must have mechanisms that minimize energy consumption, such as

This section intends to only cite the proposed protocols. They were divided according to two different types of traffic (divergent and convergent), and evaluated to demonstrate

The proposed protocol for divergent traffic consists of four parts: it is based on the GPSR protocol (KARP and KUNG, 2000), which has two modes, greedy and perimeter (i); the second part is that when it reaches a particular target region, indicated by the geodesic coordinates, it spread the message, thus operating in *geocast* mode (ii); the third part is that it is able to reverse the direction of the perimeter mode, in order to go around blank spaces competently (iii); finally, the last part consists of retransmitting to different neighbors in case a fail occurs, using the original GPSR criterion to chose neighbors (iv). Originally, GPSR uses the right-hand rule to define the node to retransmit the package, choosing the neighbor by the smaller angle. Then, to reverse the direction, the logic was reversed, using the left-hand

For detailed information about the protocol used for divergent traffic, including flowcharts

periodically switching the radio off, since devices would be idle most of the time.

rule. Figure 6 shows the mode of operation of the protocol for divergent traffic.

protocols can then implement mechanisms that use such information.

which are more suitable for the mentioned urban network.

and analyses, refer to Pantoni and Brandão (2011).

destinations.

protocols to be specifically developed.

satisfactory delivery rate.

**5.1. Divergent traffic** 

energy consumption to exchange information.

**Figure 5.** Application Architecture

The communication standard adopted between the operation and the industrial computer is CyberOPC. CyberOPC is an academic research project that proposes an open communication system, based on HTTP (Hyper Text Transfer Protocol), specially developed for remote control and supervision of industrial systems over public IP (Internet Protocol) networks (TORRISI, 2011).

Communication works as follows: management applications installed on the Operation computer request control and supervision data via the Ethernet network to the industrial computer installed on the compartment. The message is received by the computer and transferred to the communication controller connected to the serial port.

The communication controller transmits the message via the wireless network, identifying the request. The sensor nodes receive the notifications, process the request and transmit the response to the controller via the wireless network. The response is received by the controller via the wireless network, and retransmitted to the computer via the serial port. The industrial computer sends the response to the operation computer via the Ethernet network.

For detailed information about this control and monitoring application, refer to Fonseca (2011).
