Developing and Testing of Software for Wireless Sensor Networks - Networked Embedded Systems - page 297

Target node Sensor node Sink node

Target application Sensor application

Sensor application

Sensor stack Sensor stack Communication stack Communication stack

Target agent Target agent Network layer Network layer

Physical access Physical access MAC layer MAC layer

Sensor Channel Sensor channel Wireless communication channel

FIGURE . Model of a sensor network using SensorSim in J-Sim.

to other network simulators, such as ns-, which often crashes throwing out of memory exceptions
in large networks with thousands of nodes. he Sensorsim framework additionally defines

• Three types of nodes (sink node, target node, and sensor node)
• Sensor models
• Wireless communication channels
• Environmental models (mobility and power modi)

hesensornetworkinSensorSimismodeledasvisualizedinFigure..hewirelesscommuni-
cation channel defines the communication between sink nodes and other sensor nodes. In contrast,
the sensor channel is used to detect signals such as positions or measured data.
All nodes are additionally linked with power models to estimate the power consumption precisely.
Further, the framework supports components to track nodes using a NodePositionTracker or to emu-
late routing protocols such as ad hoc on-demand distance vector routing (AODV) [] or geometric
routing such as greedy perimeter stateless routing (GPSR) [].
The presented framework SensorSim of J-Sim provides a very flexible way to configure a realistic
scenario of wireless sensor networks. As an alternative, GloMoSim may be used to simulate wire-
less networks []. In contrast to J-Sim and GloMoSim, the simulation environment OPNET uses a
hierarchical arrangement of components as used in the Internet to simulate networks [].

12.5 Mastering Deployed Sensor Networks

Development of sensor network applications is a challenging task. As a consequence of deploying
large-scale networks, an administrator of a sensor network may need to monitor areas of inter-
est, and usually wants to control the deployed network (Figure .). While specific single sensor
information has no high relevance, trends, histories, and variances are very important.
Especially nontechnicians should be able to monitor and administrate their applications eas-
ily. Powerful graphical user interfaces are required to simplify deployment, control, and monitor
large-scale wireless sensor networks in their application domains such as logistics, safety systems,
and environment applications. These software mastering environments are usable for application
developers, administrators, and maintainers, too. Typical tasks of these tools are

• Deployment and initial setup of sensor nodes
• Easy configuration of the whole network or few sensor nodes as well