Decentralized Boundary Detection without Location Information in Wireless Sensor Networks

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Decentralized Boundary

Detection without Location

Information in Wireless

Sensor Networks

Wei-Cheng Chu Kuo-Feng Ssu

Institute of Computer and Communication Engineering Department of Electrical Engineering

National Cheng Kung University Tainan, Taiwan

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Outline

 _Introduction  _{Related work}

 _{Network assumptions}

 _{Decentralized Boundary Detection (DBD)}

 _Simulation  _Conclusions

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Introduction

 _{Wireless sensor networks have a wide range of}

applications

 _{The environment may contain physical obstacles}

and communication holes

 _{A hole or a physical obstacle can be regarded as}

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Motivation

 _{Obstacle detection (or boundary detection) is a}

major concern in most WSN applications

 _{Previous detection mechanisms are}

topology-based, which are not suitable for the dynamic hole detection

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Goals

 _Distributed  _{Location-free}

 _{Dynamic hole detection}  _{Correctness guaranteed}

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Related Work (THD)

 _{S. Funke and C. Klein, “}_{Hole Detection or: “How}

much Geometry hides in Connectivity?””

Breakpoint Broken contour 1 2 3 1 2 3 s s

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Related Work (TTG)

 _{D. Dong, Y. Liu, and X. Liao, “}_Fine-grained

Boundary Recognition in Wireless Ad Hoc and

Sensor Networks by Topological Methods”

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Related Work (BR)

 _{O. Saukh, R. Sauter, M. Gauger, and P. J.}

Marron, “On Boundary Recognition without Location Information in Wireless Sensor

Networks”

Flower structure Fail to construct the flower structure

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Assumptions and System Model

 _{Location-free}

 _{Non-unit disk graph}

 d-Quasi Unit Disk Graph (d-QUDG)

 _{Each edge is a two-way communication link}

 _{Each node is aware of its one, two, and three-hop}

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Overview

s

Broken contour Contour

s

A boundary node should be nearby a broken contour

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Definition of Hole

 _{Hole cycle}_{: a cycle with length larger than three}

and it cannot be decomposed into several cycles with smaller length

 _Hole_{: the face formed by hole cycle}

Hole

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Rule 1

 _{For the hole cycle with length larger than five}

 Determines whether the contour in two-hop neighbor graph is broken or not

Broken contour

Node s is a boundary node

s s

s

The contour in one-hop neighbor graph is difficult to determine whether it is broken or not

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s

Exception of Rule 1

 _{Not able to identify the hole cycle with length}

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s

Rule 2

 _{For the hole cycle with length smaller than six}

 Identifies the hole cycle in one, two-hop neighbor graph

s

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Correctness Proof

 _{Step 1}_{: A hole cycle has continuity and}

consistency properties

 _{Step 2}_{: All nodes of hole cycles can be identified}

 _{Step 3}_{: All boundary nodes near or belonging to}

hole cycles

 _{Step 4}_{: The identified boundaries of DBD contain}

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Simulation

 _{Network field: 600m × 600m}

 _{Communication range: 20m}

 _{Embeddings: UDG and 0.7-QUDG}

 _{Number of nodes: 700 to 2200}  _{Number of runs: 100}

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Control Overhead

 _{The control overhead is calculated as the average}

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Detection Results (1/4)

 _{UDG with degree 12}

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Detection Results (2/4)

 _{UDG with degree 12}

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Detection Results (3/4)

 _{0.7-QUDG with degree 12}

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Detection Results (4/4)

 _{0.7-QUDG with degree 12}

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Conclusions

 _{No UDG constraint}

 _{Any length of hole cycle can be detected}

 _{Requires only 3-hop neighbors’ information}

 _{Can be applied in the environment with mobile}

nodes

 _{The accuracy of hole shape is better than previous}

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