Incidentally, this was the largest wireless sensor network deployed on the ground
till year 2004.
261 Chapter 11 Maximizing the Lifetime of an Always-On WSN Application
Santosh Kumar, Anish Arora, and Ten H. Lai
further extends it to 36 days (Section 4.5). If it were possible to eliminate the
periodic control messages, the ExScal network could be made to last 48 days,
which represents a lifetime extension by 16 times (Section 4.6). Using other
schemes such as in-network data aggregation and reduced reprogramming
can increase the lifetime of ExScal further and none of these schemes require
deploying any more sensor nodes in the network than are absolutely necessary
to provide the desired level of monitoring.
After reading this chapter, the readers will be able to assess the suitability
of various fine-grained power management approaches for always-on applications
of wireless sensor networks. More importantly, our measured data and
lifetime analysis will help readers formulate better (i.e., more accurate) models
in their research on power management. For example, the assumption that
a mote from the Mica family (a popular sensor platform) [7, 14] lasts 3??“5 days
on a pair of AA batteries if deployed in an always-on sensor network should be
changed to 30??“50 days. Also, the claim that in-network data aggregation can
extend the network lifetime by more than 50% becomes questionable because
our analysis reveals that in-network data aggregation can extend the lifetime
of ExScal by at most 8.
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