Within a sensor cluster, there are many small sensor nodes (SNs) that capture
relevant information from the designated area, and there is at least one
application node (AN) that receives raw data from these SNs, creates a comprehensive
local-view, and forwards the composite bit-stream toward a BS. In
practice, both SN and AN are battery-powered and energy-constrained, and
their node lifetimes directly a?®ect the network lifetime of sensor networks.
In [109], they focused on the topology control process for ANs and BSs, which
constitute the upper tier of a two-tiered sensor network. They proposed approaches
to maximize the topological network lifetime, by arranging BS location
and inter-AN relaying optimally.
6 Conclusion
This chapter presented an overview of various techniques used for topology
control protocols in wireless sensor networks. Mainly, two kinds of approaches
were reviewed: geometric structures and virtual backbones. We first reviewed
several sparse geometric spanners which can be built locally and used as the
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Yu Wang
underlying network topology. Spanner property can guarantee the power ef-
ficiency of a unicast route on these spanners. Then, we described three lowweight
geometric structures for power e?±cient broadcasting in sensor networks
and gave the localized algorithms to build them. Later, we also surveyed techniques
of how to form virtual backbones based on connected dominating sets or
weighted connected dominating sets.
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