Wideband Power Line Positioning for Indoor Localization
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Transcript of Wideband Power Line Positioning for Indoor Localization
Wideband PowerLine Positioning for Indoor
LocalizationErich Stuntebeck (Georgia Tech) - Shwetak Patel (U.
Washington)Thomas Robertson (Georgia Tech) - Matthew
Reynolds (Duke) Gregory Abowd (Georgia Tech)
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OverviewPatel et al. (UbiComp 2006) introduced PowerLine Positioning (PLP-I), a fingerprinting-based indoor localization system.
PLP-I Limitations
• Sub-optimal frequency-pair selection.
• Sensitivity to noise.
• Temporal stability.
Solution: replace the frequency-pair approach with a wideband signal.
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PLP-I Background
S. Patel, K. Truong, G. Abowd. “PowerLine Positioning: A Practical Sub-Room-LevelIndoor Location System for Domestic Use”, UbiComp 2006.
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PLP Background
• Amplitudes create a unique signature at every physical location.
• Initial site survey required.
• K-Nearest-Neighbors used for post-site-survey mapping.
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PLP-I Status
•Works as expected in residential environments and is currently undergoing commercialization.
•Problems in commercial environments with lots of electrical equipment.
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Our Test Environments
Technology Square Research Building
Georgia Tech Aware Home
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Data Collection• 66 surveyed grid-points
on a best-effort 0.9m x 0.9m grid.
• 3 Levels of classification
• Room
• Sub-Room
• Grid
• 5 sweeps conducted over 2 months.
8Measurement Apparatus• Software radio used to record raw over-the-air
waveforms with a 64 MHz ADC.
• Broadband loop-antenna used for prototyping speed and flexibility.
• Necessary hardware has been reduced to portable size for deployments in the future.
Locator “tag”
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Signal Injection• One signal injector
located in the kitchen.
• 40 signals (pure unmodulated carrier waves) tested ranging from 500 kHz to 20 MHz, plus 447/448/600/601 kHz.
• All 44 tested frequencies injected in sequence from the indicated point.
10Classification
Results• KNN classification of 66
grid-points using a K value of 1.
• Frequency pairs chosen independently for each of the three granularities for worst and best cases.
• Test and training data captured several hours apart.
Patel et al. ’06 results67% accuracy @ 1m
8.5
MH
z, 9
.0 M
Hz
8.5
MH
z, 1
1.0
MH
z
447 k
Hz,
11.5
MH
z
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Noise Sensitivity
• How sensitive is two-frequency amplitude data to noise?
• Added zero-mean Gaussian noise.
• Trained on the original uncorrupted data and tested on the corrupted data.
2 dB
12How much noise
exists?
13How much noise
exists? 5 Datasets over 2 Months
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Proposed Solution
•Frequency pair approach suffers from poor performance and noise sensitivity.
•Proposed solution: wideband signaling
•Use all 44 tested frequency amplitudes for classification - 44 dimensional classifier space.
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Wideband Results
16Do you need 44
frequencies?
17Wideband Noise
Resistance
Narrowband, 2 Frequency Wideband, 44 Frequency
18Wideband Temporal
Stability
19Wideband Temporal
Stability
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Summary
PLP-I Limitations
• Sub-optimal frequency-pair selection.
• Sensitivity to noise.
• Temporal stability.
Solution: replace the frequency-pair approach with a wideband signal.
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Future Work
•Further experimentation on temporal stability and accuracy vs. wideband signal size / frequency component spacing.
•Other techniques for improvement in temporal stability?
•Adaptive solution - continually monitor powerline noise.
Wideband PowerLine Positioning for Indoor
LocalizationErich [email protected]