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Ripple II: Faster Communication through Physical Vibration Nirupam - - PowerPoint PPT Presentation
Ripple II: Faster Communication through Physical Vibration Nirupam - - PowerPoint PPT Presentation
Ripple II: Faster Communication through Physical Vibration Nirupam Roy, Romit Roy Choudhury University of Illinois at Urbana-Champaign NSDI, March 18, 2016 Santa Clara, CA Short range communication: a new need of this decade Short range
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Short range communication: a new need of this decade
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Emerging technologies for short range
Security / Privacy Convenience Energy
Driving forces of short range communication research
Capacity Availability Health
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Emerging technologies for short range
Visible Light Communication Acoustic NFC
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Physical vibration: a new mode of communication
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Physical vibration: a new mode of communication
Vibration Motor Accelerometer
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Physical vibration: a new mode of communication
Vibration Motor Accelerometer
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Application Vibratory Radio
Single-Carrier Multi-Carrier Spatial channels Phy-Security Morse-code
Hardware
6 bps 80 bps 200 bps 400 bps +secured
Ripple: vibratory communication
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32K
Ripple - II
9.6K 106K 1.0K 0.3K
NFC Infrared Visible Light Ultrasound
0.2K Ripple - I
Search for a better Ripple
(bits-per-second, entry level versions)
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Hardware front-end Vibration recovery at the receiver Transmitter side rate control
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Hardware front-end Vibration recovery at the receiver Transmitter side rate control
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A better sensor for physical vibration
The transmitter:
Driving voltage
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Vibration
Accelerometer
A better sensor for physical vibration
Amplitude Frequency 1K 10K 15K Amplitude Frequency 5K 1K 10K 15K 5K
The receiver:
+
- Vibration
+ Sound
Microphone
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A better sensor for physical vibration
Amplitude Frequency 1K 10K 15K 5K
OFDM
The receiver:
+
- Vibration
+ Sound
Microphone
Vibration
Accelerometer
Amplitude Frequency 1K 10K 15K 5K
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A better sensor for physical vibration
Amplitude Frequency 1K 10K 15K 5K
+
- Vibration
+ Sound
Microphone OFDM
But wait… The receiver:
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A better sensor for physical vibration
Amplitude Frequency 1K 10K 15K 5K
+
- Vibration
+ Sound
Microphone OFDM Ambient sound
The receiver:
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Hardware front-end Vibration recovery at the receiver Transmitter side rate control
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Primary mic. Vibration Sound V+S V S Secondary mic. S S
- V
Vibration recovery at receiver
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V Primary mic. Vibration Sound V+S V S Secondary mic. S” S”
Adaptive Filter
Vibration recovery at receiver
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V Primary mic. Vibration Sound V+S V S Secondary mic. S” S”
Adaptive Filter
V”+ V”
Vibration recovery at receiver
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V Primary mic. Vibration Sound V+S V S Secondary mic. S” S”
Adaptive Filter
V”+ V”
Vibration recovery at receiver
Signal sources are correlated
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V Primary mic. Vibration Sound V+S V S Secondary mic. S” S”
Adaptive Filter
V”+ V”
Vibration recovery at receiver
Symbol Selective Adaptive Filtering
Signal sources are correlated
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Vibration recovery at receiver
Amplitude Frequency Ambient sound Vibration frequency bins
Noise is sparse in frequency Static channel between the sensors
H Primary mic. Secondary mic.
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Vibration recovery at receiver
Amplitude Frequency
Static channel between the sensors
Primary mic. Secondary mic.
Amplitude Frequency
Relative estimate
- f the channel
H
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Selected bins (primary mic.) Selected bins (secondary mic.)
Adaptive Filter
Corrected bins
Vibration recovery at receiver
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Hardware front-end Vibration recovery at the receiver Transmitter side rate control
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Symbol 07 Symbol 06 Symbol 05 Symbol 04 Symbol 03 Symbol 02 Symbol 01 Packet 02 Packet 01 Transmitter side Receiver side
MAC layer rate control
1
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Symbol 07 Symbol 06 Symbol 05 Symbol 04 Symbol 03 Symbol 02 Symbol 01 Packet 02 Packet 01 ACK Interference sensing Transmitter side Receiver side
MAC layer rate control
2
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Symbol 07 Symbol 06 Symbol 05 Symbol 04 Symbol 03 Symbol 02 Symbol 01 Packet 02 Packet 01 ACK Interference sensing Transmitter side Receiver side
MAC layer rate control
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Back-EMF
MAC layer rate control
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Back-EMF
MAC layer rate control
Symbol 01
“Listening through a Vibration Motor”
Nirupam Roy, Romit Roy Choudhury [MobiSys 2016]
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Back-EMF
MAC layer rate control
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Symbol 07 Symbol 06 Symbol 05 Symbol 04 Symbol 03 Symbol 02 Symbol 01
OFDM symbols
MAC layer rate control
Low “Signal to Interference and Noise Ratio” (SINR)
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Symbol 07 Symbol 06 Symbol 05 Symbol 04 Symbol 03 Symbol 02 Symbol 01 Symbol 06 Symbol 05 Symbol 02
OFDM symbols Corrupted symbols
MAC layer rate control
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Symbol 07 Symbol 06 Symbol 05 Symbol 04 Symbol 03 Symbol 02 Symbol 01 Symbol 06 Symbol 05 Symbol 02 Symbol 06 Symbol 05 Symbol 02 Symbol 08 Symbol 07 Symbol 09
OFDM symbols Corrupted symbols Symbol retransmission
MAC layer rate control
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Symbol 07 Symbol 06 Symbol 05 Symbol 04 Symbol 03 Symbol 02 Symbol 01 Symbol 06 Symbol 05 Symbol 02 Symbol 06 Symbol 05 Symbol 02 Symbol 08 Symbol 07 Symbol 09
OFDM symbols Corrupted symbols Symbol retransmission
MAC layer rate control
How can the receiver detect a duplicate symbol? What is the data-rate of the duplicate symbol?
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Symbol 01 Symb Schmidl-Cox
- sync. algo.
- l 01
MAC layer rate control
Half of the symbol per retransmission Identical halves in the time domain signal Algorithm detects this special symbol at the receiver Doubles per bit energy Data in alternate frequency bins
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Evaluation
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Evaluation
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Evaluation
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Evaluation
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Vibrations do not broadcast Vibrations do not tether Vibratory communication
Applications
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Applications
RECEIVE
Touch activated smart-lock Communication through bone conduction P2P money transfer
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