DEPARTMENT OF COMPUTING
电子计算学系
Wi-Sleep: Contactless Sleep Monitoring
via WiFi Signals
Xuefeng Liu1, Shaojie Tang2, Jiannong Cao1, Jiaqi Wen1
1. Dept. of Computing, The Hong Kong Polytechnic University
2. Jindal School of Management, UT Dallas
Presenter: Qixin Wang1
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DEPARTMENT OF COMPUTING
电子计算学系
Outline
Motivation
Related works
Breath detection using WiFi signals
Experiment
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DEPARTMENT OF COMPUTING
电子计算学系
Sleep Monitoring Systems: Class 1
Obtrusive to
the users
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DEPARTMENT OF COMPUTING
电子计算学系
Sleep Monitoring Systems: Class 2
High cost
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Affected by light
Privacy issue
DEPARTMENT OF COMPUTING
电子计算学系
Low cost
Touch-less
Environmentally robust
Privacy- preserved
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DEPARTMENT OF COMPUTING
电子计算学系
Can Wireless Radios Work?
Low cost
Non-intrusive
Environmentally robust
No privacy concerns
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DEPARTMENT OF COMPUTING
电子计算学系
Existing works
Using RSSI (Received Signal Strength Indicator)
for tracking respiration
Drawbacks:
• Low sensitivity  Low accuracy
• The effect of different sleeping postures is not investigated
O. J. Kaltiokallio and et al., “Non-invasive respiration rate monitoring using a
single cots Tx-Rx pair,” in IPSN 2014.
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DEPARTMENT OF COMPUTING
电子计算学系
Any better wireless features than RSSI ?
Packet loss rate (PLR)
LQI (Link quality indicator)
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?
DEPARTMENT OF COMPUTING
电子计算学系
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DEPARTMENT OF COMPUTING
电子计算学系
Channel State Information (CSI)
CSI: Using Intel Wi-Fi Wireless Link 5300
802.11n MIMO radios, can provide real-time
channel state for 30 subcarrier groups
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DEPARTMENT OF COMPUTING
电子计算学系
CSI Amplitude and Phase
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DEPARTMENT OF COMPUTING
电子计算学系
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DEPARTMENT OF COMPUTING
电子计算学系
Why CSI Works?
LOS
Exhale
Inhale
Exhale
Inhale
NLOS
(a)
LOS   NLOS
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Reflection
Diffusion
Scattering
(b)
NLOS   NLOS
DEPARTMENT OF COMPUTING
电子计算学系
The CSI Data Processing
Outlier removal using the median filter
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DEPARTMENT OF COMPUTING
电子计算学系
The CSI Data Processing
Interpolation and wavelet-based noise filtering
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DEPARTMENT OF COMPUTING
电子计算学系
The CSI Data Processing
Why choose wavelet filter instead of a general
low-pass filters?
Wavelet filter can preserve edge information, which will
be utilized when detection postures changes.
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DEPARTMENT OF COMPUTING
电子计算学系
The CSI Data Processing
Channel Selection using the Recurrence Plot
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DEPARTMENT OF COMPUTING
电子计算学系
The CSI Data Processing
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DEPARTMENT OF COMPUTING
电子计算学系
The CSI Data Processing
Final result
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DEPARTMENT OF COMPUTING
电子计算学系
The Effect of Sleeping Positions
6 sleeping positions
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DEPARTMENT OF COMPUTING
电子计算学系
The Effect of Sleeping Positions
When TX and RX are at the two sides of the person
Channel Selection using the Recurrence Plot
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DEPARTMENT OF COMPUTING
电子计算学系
The Effect of Sleeping Positions
The rationale
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DEPARTMENT OF COMPUTING
电子计算学系
The Effect of Sleeping Positions
When TX and
RX are at the
same side of
the person
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DEPARTMENT OF COMPUTING
电子计算学系
The Effect of Sleeping Positions
Three pairs of TX-RX
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DEPARTMENT OF COMPUTING
电子计算学系
The Effect of Sleeping Positions
Identifying Sleeping Positions via difference in periodicity
level
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DEPARTMENT OF COMPUTING
电子计算学系
Experimental Results
False positives and negatives
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DEPARTMENT OF COMPUTING
电子计算学系
Experimental Results
Tracking respiration with fixed sleeping positions
TX1-RX2 (different side)
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TX1-RX1 (same side)
DEPARTMENT OF COMPUTING
电子计算学系
Experimental Results
Identifying sleeping positions
A : sleep on the back
B : sleep on the left side
C : sleep on the right side
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DEPARTMENT OF COMPUTING
电子计算学系
THANK YOU
Q&A
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