wilamowski-b-m-irwin-j-d-industrial-communication-systems-2011

Industrial Strength Wireless Multimedia Sensor Network Technology 11-3
embedded processor, communication channel, and power module. The embedded processor is generally
used for collecting and processing the signal data taken from the sensors. Sensor element produces a
measurable response to a change in the physical condition like temperature, humidity, measuring carbon
dioxide, etc. The wireless communication channel provides a medium to transfer the information
extracted from the sensor node to the exterior world, which may be a computer network, and inter-node
communication. Finally, power unit mostly comprises AA-size batteries and dc–dc module for feeding
the entire WSN node.
11.2.1 WSN System Requirements
Here, we discuss some of the characteristic requirements of a system comprising wireless sensor nodes.
The system should be
1. Fault tolerant: The system should be robust against node failure (running out of energy, physical
destruction, H/W, S/W issues, etc.).
2. Scalable: The system should support a large number of sensor nodes to cater for different
applications.
3. Long life: The node’s lifetime entirely defines the network’s lifetime and it should be high enough.
The sensor node should be power efficient against the limited power resource that it has since it is
difficult to replace or recharge thousands of nodes. The node’s communication, computing, sensing,
and actuating operations should be energy efficient too.
4. Programmable: The reprogramming of sensor nodes in the field might be necessary to improve
flexibility.
5. Secure: The system should have the following:
a. Access control: To prevent unauthorized attempts.
b. Message integrity: To detect and prevent unauthorized changes in the message.
c. Confidentiality: To assure that sensor node should encrypt messages so that only those nodes
that have the secret key would listen.
d. Replay protection: To assure that sensor node should provide protection against an adversary
reusing an authentic packet for gaining confidence/network access; man-in-the-middle
attack can be prevented by time-stamping the data packets.
6. Affordable: The system should use low-cost devices since the network comprises thousands of
sensor nodes. The installation and maintenance of system elements should also be significantly
low to make its deployment realistic.
11.2.2 Wireless Multimedia Sensor Networks
Wireless sensor network node, if equipped with audio- or video-sensing device, forms a WMSN node as
shown in Figure 11.3. And the network formed by such nodes (WMSN) is defined as a network of wirelessly
interconnected devices that are able to ubiquitously retrieve multimedia content such as video and
audio streams, still images, and scalar sensor data from the environment. The key application in which
WMSN is widely used includes surveillance systems, intelligent traffic management systems, habitat
monitoring, and military applications. All these applications are heterogeneous by nature as they not
only require scalar information but also multimedia information as well. Multitier WMSN architectures
are generally used for these applications to have a complete understanding of the environment
WSN
Multimedia
(video + audio)
WMSN
FIGURE 11.3
Wireless multimedia sensor network evolution from WSN.
© 2011 by Taylor and Francis Group, LLC