A Distributed Localization Scheme for Wireless Sensor Networks with Improved Grid-Scan and Vector- Based Refinement Jang-Ping Sheu, Pei-Chun Chen, and Chih- Shun Hsu IEEE Transactions on Mobile Computing 2008

Outline Introduction Related Work Distributed Range-Free Localization Scheme Performance Evaluation Conclusions

Introduction Localization is a fundamental and essential issue for WSNs Many applications and communication protocols are based on location information Tracking Geographic-based routing Geocasting

Introduction Localization Algorithms Range-based TOA, TDOA, AOA, RSSI..etc. Range-free Centroid, APIT, DV-HOP, CPE..etc.

Introduction Range-based often need to be equipped with additional hardware are impractical solutions for WSNs Range-free Existing range-free schemes are either too costly (heavy traffic load), not accurate enough, or not scalable

Introduction To improve the previous works, this paper proposes a Distributed Range-Free Localization Scheme (DRLS) for static WSNs.

Related Work Centroid Algorithm

Related Work Convex Position Estimation (CPE) Algorithm

Distributed Range-Free Localization Scheme Beacon Exchange Improved Grid-Scan Algorithm Refinement The Impact of the Farther Anchor Refinement of the Estimated Location

Beacon Exchange Every anchor gathers the ID and location information of anchors within tow hops

Distributed Range-free Localization Scheme CPE DRLS

Improved Grid-Scan Algorithm

Refinement The Impact of the Farther Anchor A1A1 A2A2 Anchor node Normal node Estimated location D invasion N’ N VF N’

Refinement Refinement of the Estimated Location D invasion A4max VF A4max

Refinement A1A1 A2A2 Anchor node Normal node N’ N Estimated location A3A3 A4A4 A5A5 L3L3 b c d e

Refinement A1A1 A2A2 Anchor node Normal node N’ N Estimated location A3A3 A4A4 A5A5 L3L3 c d D invasion A3max D invasion A3 VF A3max

Performance Evaluation Simulator : NS2 DOI (degree of irregularity) : 0.5 Area Size : 10r * 10r Number of nodes : 200

Performance Evaluation

Ratio of anchors = 40 percent

Performance Evaluation Anchor Ratio

Performance Evaluation Ratio of anchors = 33 percent

Performance Evaluation Number of sensor nodes = 25

Conclusions This paper proposes a fully distributed scheme range-free localization scheme for WSNs Simulation and experimental results show that the proposed scheme can achieve better accuracy than the other localization scheme

Thank You!