Localization
, Location information is essential to identify, for example, where
sensor readings originated from and to track events and targets
, Location information has numerous other applications
support of context-based routing protocols
geographic routing protocols
location-aware services
enhanced security protection mechanisms
, Many devices embedded in real-world artifacts, so GPS is not an
option
, Software-based solutions explored in WSN world
Often require many anchor nodes (nodes with known location) or iterations (or both)
to achieve high accuracy
Ranging measurements helpful where available, but not always available or of
sufficient accuracy to be useful