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Localization and Secure Localization
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Localization and Secure Localization

Feb 24, 2016

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Localization and Secure Localization. Learning Objectives. Understand why WSNs need localization protocols Understand localization protocols in WSNs Understand secure localization protocols. Prerequisites. Module 7 Basic concepts of network security Basic concepts of computer networks. - PowerPoint PPT Presentation
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Page 1: Localization and Secure Localization

Localization and Secure Localization

Page 2: Localization and Secure Localization

Learning Objectives

• Understand why WSNs need localization protocols

• Understand localization protocols in WSNs• Understand secure localization protocols

Page 3: Localization and Secure Localization

Prerequisites

• Module 7• Basic concepts of network security• Basic concepts of computer networks

Page 4: Localization and Secure Localization

The Problem

• The determination of the geographical locations of sensor nodes

• Why do we need Localization?– Manual configurations of locations is not feasible

for large-scale WSNs– Location information is necessary for some

applications and services, e.g. geographical routing– Providing each sensor with localization hardware

(e.g., GPS) is expensive in terms of cost and energy consumption

Page 5: Localization and Secure Localization

Localization

• In some applications, it is essential for each node to know its location

• Global Positioning System (GPS) is not always possible– GPS cannot work indoors– GPS power consumption is very high

Page 6: Localization and Secure Localization

Solutions

• Range-based– Use exact measurements (point-to-point distance

estimate (range) or angle estimates)– More expensive– Ranging: the process of estimating the distance

between the pair of nodes• Range-free

– Only need the existences of beacon signals– Cost-effective alternative to range-based solutions

Page 7: Localization and Secure Localization

Localization Algorithms in WSNs• Beacon Nodes know their locations• Range-based Algorithms

– Sensor nodes need to measure physical distance-related properties

– How to measure distance• RSSI (Received Signal Strength Indication)• ToA (Time of Arrival)• TDOA (Time Difference of Arrival)

– How to estimate location• MMSE (Minimum Mean Square Estimation)

• Range Free Algorithms– Do Not involve distance estimation

Page 8: Localization and Secure Localization

Localization Algorithms in WSNs

Beacon Nodes

Sensor Node Which need to estimate its location

d0

d1

d2

(x0, y0)

(x1, y1)

(x2, y2)Trilateration

Page 9: Localization and Secure Localization

Range-based Solutions - MMSE

• MMSE:– Minimum Mean Square

Estimation

Beacon Nodes

Sensor Node Which need to estimate its location

dN

d1

d2

How to estimate (x0, y0)?

(x1, y1)

(x2, y2)

(xN, yN)

Page 10: Localization and Secure Localization

Range-based Solutions - MMSE

• Ideally, ei should be 0

Page 11: Localization and Secure Localization

Range-based Solutions - MMSE

• Rearrange the previous equations, we have

• We have N equations

Page 12: Localization and Secure Localization

Range-based Solutions - MMSE

• Eliminate , we get the following N-1 equations

• Hx = z

Page 13: Localization and Secure Localization

Range-based Solutions - MMSE

• H

Page 14: Localization and Secure Localization

Range-based Solutions - MMSE

• z

Page 15: Localization and Secure Localization

Range-based Solutions - MMSE

• x

• Solution

Page 16: Localization and Secure Localization

Range-free Approach - Centroid

• Ref[Loc_1], Section 2.1

Page 17: Localization and Secure Localization

Security Concerns in WSNs

• Secure Localization Problem

Beacon Nodes

Sensor Node Which need to estimate its location

Compromised Beacon Signals

• Secure Localization Solutions

Page 18: Localization and Secure Localization

Secure Localization

• Attack-resistant Minimum Mean Square Estimation

• Ref[Loc_2]

Page 19: Localization and Secure Localization

Attack-resistant Minimum Mean Square Estimation

Page 20: Localization and Secure Localization

Minimum Mean Square Estimation

• Ref[Loc_2], Section 2

• The more inconsistent a set of location references is, the greater the corresponding mean square error should be

Page 21: Localization and Secure Localization

Impact of Malicious Beacons

Page 22: Localization and Secure Localization

Impact of Malicious Beacons

Page 23: Localization and Secure Localization

Minimum Mean Square Estimation

• τ is important: Depend on many factors

Page 24: Localization and Secure Localization

How to Decide the set of Consistent Location References?

• Given a set L of n location references and a threshold τ– Optimal solution– Greedy solution

Page 25: Localization and Secure Localization

How to decide τ?

• Measurement error model• How to obtain?

– Study the distribution of the mean square error when there are no malicious attacks

Page 26: Localization and Secure Localization

Voting-based Location Estimation – Basic Ideas

Page 27: Localization and Secure Localization

Iterative Refinement

• The larger the number of cells– More state variables need to be kept– The smaller each cell will be – precision

• Iterative Refinement– Initially, the number of cells is chosen based on

memory constraints– After the first round, the node may perform the

voting process on the smallest rectangle that contains all the cells having the largest vote

Page 28: Localization and Secure Localization

Assignment

• 1. What is the basic idea of the MMSE-based localization protocols in wireless sensor networks?

• 2. What is the basic idea of the MMSE-based secure localization protocols in wireless sensor networks?

• 3. What are the differences between range-based and range-free localization algorithms?