ISSN : 1796-2021
Volume : 4    Issue : 4    Date : May 2009

Radio Proximity Detection in a WSN to Localize Mobile Entities within a Confined Area
Chakib Baouche, Antonio Freitas, and Michel Misson
Page(s): 232-240
Full Text:
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To localize mobile entities within a confined area, a wired infrastructure is neither scalable nor
cost-effective. An alternative solution consists in deploying a Wireless Sensor Network (WSN),
made of energy-autonomous devices. In an environment where GPS is inoperative, we propose that
the position of a mobile is given relatively to a set of tag nodes deployed in the zone of activity and
signaling their position. In a symmetrical way, each mobile node is announced periodically thus
allowing a mutual detection of radio proximity (tag-mobile or mobile-mobile). During the contact the
nodes are able to share and store the information required by the localization application. This
information is then largely scattered by using the mobility of nodes to carry data up to the application
collection points.
Then arises the question about the choice of the medium access method and its performances for
the proximity detection in a cell covered by a tag node. IEEE 802.15.4 unslotted CSMA/CA being
largely used in low power WSN, we study its performances according to the density of the mobiles
and the load of the cell.

Index Terms
WSN, Contact, Localization, Unslotted CSMA/CA.