Some topology control protocols use position information.
For these protocols, it always assumes that each node knows its position
information either through a low-power Global Position System (GPS)
receiver or some other way (such as location service and localization algorithms
in [4??“6]). With the position information, we can apply computational
geometry techniques to solve some challenging questions in sensor networks.
Energy conservation is a critical issue in sensor network for the node and
network life, as the nodes are powered by batteries only. Each sensor node
typically has a portable set with transmission and reception processing capabilities.
In the most common power-attenuation model, the power to support
a link uv is assumed to be kuvk??, where kuvk is the Euclidean distance between
u and v, ?? is a real constant between 2 and 5 depending on the wireless
transmission environment.
1.2 Localized Algorithms vs Centralized Algorithms
For algorithm design, there are two types of algorithms. Centralized methods
usually give better results, but have huge communication costs. Distributed
methods or localized methods can achieve weaker results but use less communication
costs. In sensor networks, the large numbers of sensors and the
expected dynamics present unique challenges in the design of network protocols.
We believe there are significant robustness and scalability advantages
to designing protocols using localized algorithms ??” where sensors only interact
with other sensors in a restricted vicinity, but nevertheless collectively
achieve a desired global objective (such as spanner or low weight).
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