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 hard

ware are impractical solutions for WSNs

Range-free Existing range-free schemes are either too costl

y (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

1 2 3 3 2

2 3 4 3 2

2 3 4 3 2

1 2 3 3 2

1 2 1 1 1

Improved Grid-Scan Algorithm

Refinement

The Impact of the Farther Anchor

A1

A2

Anchor node

Normal node

Estimated locationDinvasion

N’

NVF

N’

Refinement

Refinement of the Estimated Location

DinvasionA4max

VFA4max

Refinement

A1

A2

Anchor node

Normal node

N’ N

Estimated location

A3

A4

A5

L3

b cd e

Refinement

A1

A2

Anchor node

Normal node

N’ N

Estimated location

A3

A4

A5

L3

c

dDinvasionA3max

DinvasionA3 VFA3max

3 33

3

Performance Evaluation

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

Performance Evaluation

Performance Evaluation

Performance Evaluation

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!