Beacon Deployment for Sensor Network Localization

Localization in sensor networks is the process of obtaining geographical location information for all deployed sensors. Localizing each sensor node is becoming increasingly important as more and more algorithms and protocols in the disciplines of routing, energy management, and security have been proposed that rely on (semi-) accurate location information. In this paper, we study a particular approach to sensor node localization that uses sequentially deployed beacons to localize sensors. Our model assumes that the localization information can be obtained by observing beacons 1-hop away from the sensors. We show that under this simplified model the beacon deployment problem, i.e., to find the minimum number of beacons, is (still) NP-complete. We then provide an approximation algorithm with a logarithmic approximation ratio based on a set cover greedy heuristic; we study both offline and online versions of this approximation. Finally, we incorporate the localization accuracy into the beacon deployment strategy by explicitly specifying the Cramer Rao bound (CRB) as the condition. We verify the performance of the proposed algorithms using simulations, and show that accurate localization can be effectively achieved using the proposed algorithms.