Networking Reference
In-Depth Information
2.1.1 Wireless Sensor Networks
To realize the idea of the WoT paradigm it is necessary to make the objects (things)
addressable, searchable, controllable, and accessible via Web. Wireless Sensor Net-
works (WSNs), composed of sensors, actuators and embedded communication hard-
ware, play a fundamental role in the connection of the physical and digital worlds
as they monitor the physical devices, gathers their data and eventually act upon
the environment. Sensors are typically capable of recognizing an event of interest
and actuators can take an action accordingly. A WSN consists in a large number
of nodes where data are collected by distributed and smart sensors associated to
the devices. The sensing data is gathered to a sink node that sends the data to
other computational devices, often more powerful, able to further processing the
sensor produced data. As individual sensor nodes do not always have an Internet
Protocol (IP) address, they cannot be directly accessible via Web. In this case,
an intermediary element is used: the Smart Gateways . A Smart Gateway acts as
a proxy between the objects and the Web, by communicating with the objects
(in this case, the sensor nodes) and making them accessible via Web. Besides
providing WSN nodes with accessibility through the Web, Smart Gateways also
perform other functions such as to translate from Internet protocols to WSN com-
munication protocols (and vice versa), and to provide added value information on
top of the produced raw sensor data. Figure 2.1 illustrates the main elements of a
WSN.
Nowadays, there are several hardware and software platforms for WSN available.
In the SmartSensor infrastructure three different platforms are currently supported:
Fig. 2.1 Elements of a
wireless sensor network
connected to the WoT
 
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