Comparison of node localization methods for sensor networks

A randomly deployed sensor network is typically not completely localizable using distance-based measurements only. Though a necessary and sufficient condition for testing whether a network is localizable has been given in the literature, how to find localizable nodes from a not fully localizable network is still open. In this paper, we try to address a connection between two well-known localization methods, the trilateration method and the WHEEL extension method, by using a graphical tool named Henneberg operations. We also study whether Henneberg operations always guarantee the localizability of a network. The localizability by a Henneberg operation-based algorithm is given. Simulation shows that the performance of this algorithm for finding localizable nodes is very close to a well-known necessary condition called 3-path condition.

I. Introduction

Location based service (LBS) is a fundamental research topic in applying sensor networks. The process of computing the location of a sensor node is called a localization problem. This process usually contains two steps: distance estimation and localization algorithm. The distance between two nodes can be either measured directly through radio signals [4] or estimated through hop-counting [3]. The localization algorithm then utilizes the distance estimates to compute the localization. Most commonly used localization algorithm is the so-called trilateration scheme. In the 2-D case, one node's location can be uniquely located through three direct connections with three position-known nodes called anchor nodes. Trilateration can run in a sequential way through adding localizable nodes into the set of anchor nodes one by one.