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A Novel Range-Free Localization Algorithm based on Optimal Anchor Placement and Reliable Anchor Selection in Wireless Sensor Network

초록/요약

In WSNs, localization is the process of determining the physical position of sensor nodes. Importance of localization arises from the need to tag the sensed data and its associate events with their location of occurrence. Location information of sensor nodes can be found by using GPS (Global Positioning System), but installing GPS in every node results in high cost and power consumption. Thus only some sensors in the network know their position using GPS. Localization algorithms utilize the position of anchors to estimate the location of other sensor nodes which does not know its position in the network. In wireless sensor networks, an unknown node estimates the distance to the anchors, and then utilizes the estimated distance to compute its position by multilateration. The localization accuracy by multilateration depends on the distance estimation accuracy and the relative positions of anchors. Since the range-free scheme is based on the connectivity information such as hop count, the distance can always be estimated with error. Actually the unknown nodes can estimate its position accurately even with three reliable anchors. However when selecting the reliable anchors, each unknown node should also consider the relative positions. Hence we study the relationship between the localization accuracy by considering the distance estimation and relative positions of anchors. From the study we find that there are two conditions need to be satisfied to improve the localization accuracy. To increase the possibility of all unknown nodes to select the reliable anchors based on the two conditions, anchor node placement needs to be considered. Hence, we propose an optimal anchor placement algorithm and reliable anchor selection scheme. Simulation results show that the proposed methods improves the localization performance better than the existing methods.

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목차

1. Introduction………………………………………………………………1
1.1 Key Issues in Wireless Sensor Networks ………………………3
1.2 Motivation …………………………………5
1.3Research Objective and Contributions …………………………7
1.4 Organization of the Thesis …………………………………8

2. Localization in WSN……………………………………………………9
2.1 Range-based Techniques ………………………………10
2.1.1 Time of Arrival (ToA) …………………………10
2.1.2 Received Signal Strength Indicator (RSSI)…………11
2.1.3 Time Difference of Arrival (TDoA)…………………13
2.1.4 Angle of Arrival (AoA) ……………………………14
2.2 Range-free Techniques ………………………………………15
2.2.1 Centroid Algorithm …………………………………15
2.2.2 Approximate Point-In Triangulation Test …………18
2.2.3 DV-hop Algorithm…………………………………22
2.3 Position Calculation …………………………………………24
2.3.1 Trilateration/Multilateration ………………………25
2.3.2 Triangulation ………………………………………27
2.4 Brief Summary of Range-free Localization ……………………27

3. A Novel Range-Free Localization Algorithm based on Optimal Anchor Placement and Reliable Anchor Selection in Wireless Sensor Network……………30
3.1 Introduction …………………………………………………………30
3.2 Related Works ………………………………………………34
3.3 Proposed Localization Technique …………………………39
3.3.1 Analysis of Relationship between the localization…39
accuracy obtained by considering the distance estimation
and relative positions
3.3.2 Proposed Anchor Placement Algorithm ……………43
3.3.3 Reliable Anchor Selection Scheme …………………45
3.3.4 Localization Scheme based on Reliable ……………47
Anchor Selection
3.4 Simulation Results ……………………………………………49
3.4.1 Analysis of Communication Cost …………………49
3.4.2 Simulation Result …………………………………50
3.4.3 Comparison of Various Anchor placement Patterns…50
3.4.4 Comparison of DV-Hop and Proposed Method ……53
4. Conclusion………………………………………………………………57
4.1 Conclusion ……………………………………………………57

References…………………………………………………………………59

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