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Design and Evaluation of a Wireless Magnetic-based Proximity Detection Platform for Indoor Applications. Xiaofan Jiang, Chieh -Jan Mike Liang, Kaifei Chen, Ben Zhang, Jeff Hsu Jie Liu, Bin Cao, and Feng Zhao Microsoft Research Asia. 20120730-Neight. Outline. MOTIVATION - PowerPoint PPT Presentation
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Design and Evaluation of a Wireless Magnetic-based
Proximity Detection Platform for Indoor Applications
Xiaofan Jiang, Chieh-Jan Mike Liang, Kaifei Chen, Ben Zhang, Jeff Hsu
Jie Liu, Bin Cao, and Feng ZhaoMicrosoft Research Asia
20120730-Neight
MOTIVATION PROXIMITY ZONE Empirical Definition EVALUATION OF EXISTING TECHNOLOGIES LIVESYNERGY PLATFORM EVALUATION OF LIVESYNERGY APPLICATION DEPLOYMENT CONCLUSIONS
Outline
To make applications intuitive to human users,
the discovered objects in the environment must be within the personal interaction sphere
Computer automatically wake up Refrigerator change its user interface Many typical low power communication
technologies, (Bluetooth, ZigBee) have difficulties maintaining robust communication zones
Motivation
propose methodologies and systematically
compare the proximity zones created by various wireless technologies(BLE, ZigBee, and RFID reader)
Design, Implement, and Evaluate a magnetic-induction based wireless proximity sensing platform
Deploying LiveSynergy in an real-world application
Contributions
Boundary sharpness: boundary of proximity zone should be binary Boundary consistency: detection should be consistent over time
PROXIMITY ZONE
Obstacle penetration: Beaconing node and listening node can be mobileand against obstructions Additional metrics:1. Range and geometric shape of zones2. Beaconing frequency achievable3. Power consumption 4. Form-Factor of the mobile tag5. Cost of overall system
PROXIMITY ZONE
Broadcasts at fixed frequency f (packets ) P = a point in space at a distance of (, , ) from
the beacon
Classification of Points
white/grey boundary:{P | Color(P, t, t’) = white} {P | Color(P, t, t’) = grey} if x, if x’ represents the decision boundary grey/black boundary:if x, if x’
Classification of Zones
Three proximity
zones
Questions?
Proximity Zones
Use support vector machines (SVM) as the
classifierseeks maximum-margin hyperplane to separate two classes
w and b are the parameters to define the hyperplane to separate the two classes.
Classifier
Two user-definable parameters: Error tolerance:- Smooth boundary vs. non-smooth boundary Tradeoff between training loss and regularization Cost parameter C Strictness:-Expect the white zone and the black zone contain no grey points-Related to error tolerance but non-symmetry
Classifier
• Cost parameter C: the cost of false positiveC’: the cost of false negative C’• Strictness parameter:
Classifier
RBF kernel as the kernel function Classifier:
RBF kernel
Kernel Trick
Size:Size of the white and grey zone, which can be computed numerically based on the boundaries. Boundary sharpness:
Fitness:How well the zone boundaries fit the data, or a confidencemeasure of the proximity zone classification.
Matrix
Questions?
Classifier
Hardware setup:• TI CC2540 BLE dev boards (transmitting on 2.4
GHz at 0 dBm),• A pair of TelosB motes with 802.15.4-
compliant TI CC24240 radio(transmitting on 2.4 GHz at 0 dBm)
• A Impinj Speedway R1000 RFID reader (transmitting on 902 MHz at 8 dBm)
Boundary Sharpness and Consistency
Parameters:• packet reception data is collected over a
period of 200 seconds• WPRR using a windows size of 3 seconds and • Strictness parameter = 0.99 Results:
Boundary Sharpness and Consistency
Boundary Sharpness
and Consistency
The user carries the receiver in the right pants
pocket- calculate PRR from 500 packets as the user changes the body orientation by 90 each round at each distance
Human Obstacle Penetration
Signal propagation and geometry:RFID antennas usually have a radiation angle less than 180 degrees Form Factor and Costs:RFID can produce a more consistent and smaller grey zone802.15.4 and BLE have advantages in both form factor and costs.
Additional Metrics
Questions?
Evaluation
Pulse Transmitter: (use AC power)Four primary hardware microcontroller (MCU) and radio magnetic transmitter tuned at 125kHz Energy metering mechanical relay for actuation.
LIVESYNERGY PLATFORM
Link Receiver: ( battery-powered)Three primary hardware 9.2cm ×5.8cm × 2.3cm enclosure• MCU and radio• 3D magnetic coil• wake up chip
LIVESYNERGY PLATFORM
Boundary Sharpness
and Consistency
human body has very little impact on the MI
signal propagation
Body orientation vs. distance
Geometry: two dimensions extends to all directions, covering 360◦ Range: maximum range (i.e., radius) is around 5m
Additional Metrics
APPLICATION DEPLOYMENT
Diners enter the cafeteria from the entrance at the lower left corner at different times
Each diner takes a different route and visits
various food counters on the way Recorded a video as the customers walk
around the cafeteria purchasing food.- Use video timestamps
Experment
Result
Values:1. Propose methodologies and systematically
compare the proximity zones2. Deploying LiveSynergy in an real-world
application
Future?1. MI still can implement in mobile phone…
Summary