Abstract
The increasing interest in systems able to provide users with
immersive services (e.g., domotics, context-aware applications,
and immersive distance learning tools) has encouraged
the development of cheap and effective platforms aimed at
tracking objects and people within a certain space. In this
context, wireless sensor networks (WSNs) can play a very
important role, since specialized sensors can be fruitfully
exploited in order to generate/receive signals by means of
which the WSN can derive the position of nodes joined to
the objects to be tracked. The paper presents an original localization platform that exploits
a single-hop WSN, based on a Microchip MCU and
a Cypress RF device, to track its moving nodes. Specifically,
the nodes of the network are divided into three sets:
the first set consists of anchor nodes that, according to the
commands from the sink (the central node of the WSN),
generate ultrasonic pulses. These pulses are received by
the second set of (moving) nodes, which estimate the pulse time trip and communicate it to the sink. Finally, the last
set is constituted by general purpose nodes that collect any
kind of data from the surrounding field. The sink gathers
all the data, computes the position of moving nodes, and transfers information to external users on the Internet. The algorithms adopted to manage the network and to localize
moving nodes are discussed. A working prototype
based upon the hardware platform, software, and protocol
described in this paper has been deployed and tested, and
some results are shown. Simulation results of the localization
system are presented to show system scalability.