However, several aspects exist that
prevent their direct application to sensor networks. In existing ad hoc wireless
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Fernand S. Cohen, Joshua Goldberg, and Jaudelice C. de Oliveira
networks it is often assumed that the number of nodes is not large, and that
the topology, although temporal, is relatively slow-changing in comparison to
sensor networks. Sensor networks have dense topologies of nodes numbering
in the thousands or even millions. These nodes are not meant to stay active
for long periods of time and are expected to eventually die out. Nonetheless,
the ad hoc routing protocols are based on many of the same constraints as
sensor network protocols and thus can be used as a platform for the design of
suitable protocols for wireless sensor networks.
In this chapter, routing protocols for sensor networks are surveyed, with
an emphasis on trajectory-centric routing mechanisms. Existing routing protocols
are classified and their advantage and disadvantages are compared. Design
trade-o?®s between constrained and unconstrained routing with regards to
e?±ciency, speed of routing, and computational complexity are discussed. Finally,
a new trajectory-centric routing mechanism, called Tra?±c Engineering
Routing (TE-Routing or TER), is described and analyzed. With the objective
of securely forwarding data in a sensor network, in TE-Routing, a preferred
trajectory is traced a priori. This is particularly needed in problems where
obstacle avoidance is necessary.
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