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represented as Java classes (inheritors of the basic net.tinyos.message.Message
class) with fields for any data that need to be exchanged (for example, an acceler-
ometer message includes integer
x
,
y
, and
z
fields) Therefore, a combination of
JavaComm and the TinyOS Java classes provides an efficient way to communicate
with the sensor network.
The TelosB node is running the TOSBase application supplied with the TinyOS
distribution. The sole purpose of this application is to relay messages coming from
the sensor network and addressed to the sink, to the desktop application that has
registered itself as a listener; and to relay messages coming from the desktop appli-
cation to specific nodes in the sensor network to which they are addressed.
SHIMMER nodes are running either of the three applications: AccelSense,
ECGSense, or OxySense. These are TinyOS applications with the purpose of utilizing
the onboard A/D converter and DMA controller to collect measurements from
respective analog sensors and then send these measurements via radio.
12.2
Interactive Street Sensing
Interactive Street Sensing (ISS) network is a wireless sensor network which offers
new approach to walking activity from medical as well as from human daily-life
perspective. This solution addresses small, but scalable network which is intended
for outdoor monitoring, but which can also be deployed for indoor monitoring.
ISS network is a small network for street monitoring and can also be referred to
as a framework for the development of large outdoor/indoor monitoring networks.
This network uses sensor nodes equipped with temperature sensors, light sensors,
and accelerometers. Main parameters which are tracked in this scenario are the
temperature level and light intensity in the street environment. These parameters
are sampled from the sensors and transferred through the network to the appropriate
host machine, where they can be processed and stored. Data processing is relatively
simple, but completely independent from the nodes in the network.
ISS also assumes network's integration into large networks, like Internet.
Main functionalities of the ISS network are street parameters monitoring, data
transfer, and data presentation on the Internet (Fig.
12.4
). Complete architecture of
the network includes three types of devices (Fig.
12.3
).
12.2.1
ISS Hardware
ISS network architecture (Fig.
12.3
) contains three conceptual parts:
•
Sensor nodes
•
Base station
•
Server
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