  The availability of positional information is of great importance in many
commercial, public safety, and military applications. The coming years will see
the emergence of location-aware networks with sub-meter accuracy, relying on
accurate range measurements provided by wide bandwidth transmissions. In this
two-part paper, we determine the fundamental limits of localization accuracy of
wideband wireless networks in harsh multipath environments. We first develop a
general framework to characterize the localization accuracy of a given node
here and then extend our analysis to cooperative location-aware networks in
Part II.
  In this paper, we characterize localization accuracy in terms of a
performance measure called the squared position error bound (SPEB), and
introduce the notion of equivalent Fisher information to derive the SPEB in a
succinct expression. This methodology provides insights into the essence of the
localization problem by unifying localization information from individual
anchors and information from a priori knowledge of the agent's position in a
canonical form. Our analysis begins with the received waveforms themselves
rather than utilizing only the signal metrics extracted from these waveforms,
such as time-of-arrival and received signal strength. Hence, our framework
exploits all the information inherent in the received waveforms, and the
resulting SPEB serves as a fundamental limit of localization accuracy.
