For most wireless sensor network (WSN) applications, the position of the sensor
nodes needs to be known. GPS has not t into WSN very well due to its price,
power consumption, accuracy, and limitations in its operating environment. Hence,
the last decade brought about a large number of proposed methods for WSN node
localization. They show tremendous variation in the physical phenomena they use,
the signal properties they measure, the resources they consume, as well as their
accuracy, range, advantages and limitations. This paper provides a high-level, com-
prehensive overview of this very active research area.