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 ID: 379613
Download Presentation The PPT/PDF document "Localization and Secure Localization" is the property of its rightful owner. Permission is granted to download and print the materials on this web site for personal, non-commercial use only, and to display it on your personal computer provided you do not modify the materials and that you retain all copyright notices contained in the materials. By downloading content from our website, you accept the terms of this agreement.
Slide1
Localization and Secure LocalizationSlide2
Learning Objectives
Understand why WSNs need localization protocols
Understand localization protocols in WSNs
Understand secure localization protocolsSlide3
Prerequisites
Module 7
Basic concepts of network security
Basic concepts of computer networksSlide4
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 consumptionSlide5
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 highSlide6
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 solutionsSlide7
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 estimationSlide8
Localization Algorithms in WSNsSlide9
Range-based Solutions - MMSE
MMSE:
Minimum Mean Square EstimationSlide10
Range-based Solutions - MMSE
Ideally,
e
i
should be 0Slide11
Range-based Solutions - MMSE
Rearrange the previous equations, we have
We have
N
equationsSlide12
Range-based Solutions - MMSE
Eliminate , we get the following N-1 equations
Hx = zSlide13
Range-based Solutions - MMSE
HSlide14
Range-based Solutions - MMSE
zSlide15
Range-based Solutions - MMSE
x
SolutionSlide16
Range-free Approach -
Centroid
Ref[Loc_1], Section 2.1Slide17
Security Concerns in WSNs
Secure Localization Problem
Secure Localization SolutionsSlide18
Secure Localization
Attack-resistant Minimum Mean Square Estimation
Ref[Loc_2]Slide19
Attack-resistant Minimum Mean Square EstimationSlide20
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 beSlide21
Impact of Malicious BeaconsSlide22
Impact of Malicious BeaconsSlide23
Minimum Mean Square Estimation
τ
is important: Depend on many factorsSlide24
How to Decide the set of Consistent Location References?
Given a set L of n location references and a threshold
τ
Optimal solution
Greedy solutionSlide25
How to decide
τ
?
Measurement error model
How to obtain?
Study the distribution of the mean square error when there are no malicious attacksSlide26
Voting-based Location Estimation – Basic IdeasSlide27
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 Slide28
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?