174 Software Networks
Another important characteristic of the protocols used in sensor
networks is service discovery, which should enable the automatic
establishment of a connection. The IETF also plays an important role
in this domain, having published several proposed solutions – one of
which is sensor-oriented: LowPAN Neighbor Discovery Extension.
This protocol is a reduction of the Neighbor Discovery standard,
which pertains to all energy-consuming elements, including
broadcasts and multicast management.
A very special example of a sensor network is offered by smart
dust, the aim of which is to develop nanotechnology sensors and to
connect them to one another by an ad hoc network. Smart dust fits
into a space smaller than a cubic millimeter – hence the name. Each
grain of this dust contains the components necessary to constitute a
communicative computer: a processor, memory, radio, battery, etc.
Here, the main problem is the saving of energy while performing
sensor functions. In particular, the network part must carry out
communications using very little energy indeed. Thus, Berkeley
University has designed a specific operating system and protocols,
known as TinyOS and Tiny protocol. TinyOS is written in simplified
C language, called nesC, which is a sort of dialect designed to
optimize memory usage.
6.18. RFID
RFID (Radio-Frequency Identification), or radio-identification,
was introduced for the purpose of identifying objects, so it is also
known as electronic tagging.
Electronic tags are scanned by a reader, which is able to recover
the identification data. The tags are used in numerous applications,
from the tracking of animals to security tags in stores.
There are two main types of electronic tags: passive and active
tags. Passive tags have no energy source. They are activated by a
reader which supplies a sufficiently strong electromagnetic field to
generate an electrical current, facilitating the radio-wave transmission
www.it-ebooks.info
Another important characteristic of the protocols used in sensor
networks is service discovery, which should enable the automatic
establishment of a connection. The IETF also plays an important role
in this domain, having published several proposed solutions – one of
which is sensor-oriented: LowPAN Neighbor Discovery Extension.
This protocol is a reduction of the Neighbor Discovery standard,
which pertains to all energy-consuming elements, including
broadcasts and multicast management.
A very special example of a sensor network is offered by smart
dust, the aim of which is to develop nanotechnology sensors and to
connect them to one another by an ad hoc network. Smart dust fits
into a space smaller than a cubic millimeter – hence the name. Each
grain of this dust contains the components necessary to constitute a
communicative computer: a processor, memory, radio, battery, etc.
Here, the main problem is the saving of energy while performing
sensor functions. In particular, the network part must carry out
communications using very little energy indeed. Thus, Berkeley
University has designed a specific operating system and protocols,
known as TinyOS and Tiny protocol. TinyOS is written in simplified
C language, called nesC, which is a sort of dialect designed to
optimize memory usage.
6.18. RFID
RFID (Radio-Frequency Identification), or radio-identification,
was introduced for the purpose of identifying objects, so it is also
known as electronic tagging.
Electronic tags are scanned by a reader, which is able to recover
the identification data. The tags are used in numerous applications,
from the tracking of animals to security tags in stores.
There are two main types of electronic tags: passive and active
tags. Passive tags have no energy source. They are activated by a
reader which supplies a sufficiently strong electromagnetic field to
generate an electrical current, facilitating the radio-wave transmission
www.it-ebooks.info