1.
KinPhy: A Kinetic In-Band Channel for Millimetre-Wave
Networks
Mohammed Alloulah
Zoran Radivojevic, René Mayrhofer, and Howard Huang
Mohammed Alloulah, Zoran Radivojevic, René Mayrhofer, and Howard
Huang. 2019. KinPhy: A Kinetic In-Band Channel for Millimetre-Wave
Networks. In The 17th ACM Conference on Embedded Networked Sensor
Systems (SenSys ’19), November 10–13, 2019, New York, NY, USA. ACM,
New York, NY, USA, 14 pages. https://doi.org/10.1145/3356250.3360039

2.
2
Bell Labs, Cambridge
Zoran Radivojevic René Mayrhofer Howard HuangMo Alloulah
Bell Labs, Cambridge JKU, Linz Bell Labs, Murray Hill

3.
0 10GHz 20GHz 30GHz 40GHz 50GHz 60GHz 70GHz 80GHZ 90GHz 100GHz
Next Gen WiFiWiFi
vast spectrum
dense, compact antenna arrays
1-1
0
0.5
2
-0.5
04
0
6
-0.5
8
0.5
-110
1
E
H
sub 6GHz
60GHz
finer wavelength
mm-wave

4.
0 10GHz 20GHz 30GHz 40GHz 50GHz 60GHz 70GHz 80GHZ 90GHz 100GHz
Next Gen WiFiWiFi
vast spectrum
dense, compact antenna arrays
1-1
0
0.5
2
-0.5
04
0
6
-0.5
8
0.5
-110
1
E
H
sub 6GHz
60GHz
finer wavelength
mm-wave
Challenge networking
orthodoxies

5.
Voltage
OFDM Waveform
-8 -6 -4 -2 0 2 4 6 8
-0.4
-0.2
0
0.2
0.4
0.6
0.8
1
Frequency
(d)
Communication
Sensing
(a)
Communication only
Communication and Sensing
Communications Payload
Sensing
Preamble
Communications Payload
Communications
Preamble
Communications
Preamble
(b)
Up
Down
Start
Frequency
End
Frequency
~~
~~
Start Time End Time
Time
Voltage
Frequency
Time
Chirp Waveform
(c)
Vision: Joint Communication & Sensing for Millimetre-Wave Networks

6.
Voltage
OFDM Waveform
-8 -6 -4 -2 0 2 4 6 8
-0.4
-0.2
0
0.2
0.4
0.6
0.8
1
Frequency
(d)
Communication
Sensing
(a)
Communication only
Communication and Sensing
Communications Payload
Sensing
Preamble
Communications Payload
Communications
Preamble
Communications
Preamble
(b)
Up
Down
Start
Frequency
End
Frequency
~~
~~
Start Time End Time
Time
Voltage
Frequency
Time
Chirp Waveform
(c)
Vision: Joint Communication & Sensing for Millimetre-Wave Networks

7.
Voltage
OFDM Waveform
-8 -6 -4 -2 0 2 4 6 8
-0.4
-0.2
0
0.2
0.4
0.6
0.8
1
Frequency
(d)
Communication
Sensing
(a)
Communication only
Communication and Sensing
Communications Payload
Sensing
Preamble
Communications Payload
Communications
Preamble
Communications
Preamble
(b)
Up
Down
Start
Frequency
End
Frequency
~~
~~
Start Time End Time
Time
Voltage
Frequency
Time
Chirp Waveform
(c)
Vision: Joint Communication & Sensing for Millimetre-Wave Networks
Built-in, high-fidelity sensing mode in next gen networks
Will make possible new compelling capabilities

8.
KinPhy Kinetic Physical Layer:=

9.
KinPhy Kinetic Physical Layer:=
Physically oscillating
metasurfaces
Trans’d
Refl’d
Transmitted
Reflected
Node 2
Node N
Node 1
…

10.
KinPhy Kinetic Physical Layer:=
Micrometre-scale vibrations of phone form factors can
backscatter information to an mm-wave router
Physically oscillating
metasurfaces
Trans’d
Refl’d
Transmitted
Reflected
Node 2
Node N
Node 1
…

11.
[I] Some Technicalities

12.
READER
CHANNEL
METASURFACE
Transmitter
Receiver
Transmitted Signal
Reflected Signal
Physical
Oscillations
KinPhy
Consists of 2 components + channel
- metasurface
- radar reader

13.
READER
CHANNEL
METASURFACE
Transmitter
Receiver
Transmitted Signal
Reflected Signal
Physical
Oscillations
Channel
Over-the-air round-trip radio signal
strength decays in 4th power of
distance

14.
READER
CHANNEL
METASURFACE
Transmitter
Receiver
Transmitted Signal
Reflected Signal
Physical
Oscillations
Channel
Prx ∝
Ptx
R4
i.e.
∝
1
R4
Over-the-air round-trip radio signal
strength decays in 4th power of
distance

15.
READER
CHANNEL
METASURFACE
Transmitter
Receiver
Transmitted Signal
Reflected Signal
Physical
Oscillations
Channel
Prx ∝
Ptx
R4
i.e.
Calls for robust metasurface modulation to compensate for
distance-dependent losses
∝
1
R4
Over-the-air round-trip radio signal
strength decays in 4th power of
distance

16.
READER
CHANNEL
METASURFACE
Transmitter
Receiver
Transmitted Signal
Reflected Signal
Physical
Oscillations
Metasurface
Consists of 2 components + channel
- metasurface
- radar reader

17.
Metasurface
Precise mechanical actuation for accurate phase modulation of reflected
mm-wave.
μm

18.
Metasurface
Precise mechanical actuation for accurate phase modulation of reflected
mm-wave.
μm
Iterative in-house prototyping

19.
Metasurface
Precise mechanical actuation for accurate phase modulation of reflected
mm-wave.
μm
Iterative in-house prototyping
Measurement
Display
Control Panel
Excitation
Amplifier
Device Under Test
Microscope

20.
Metasurface
Precise mechanical actuation for accurate phase modulation of reflected
mm-wave.
μm
Iterative in-house prototyping
Measurement
Display
Control Panel
Excitation
Amplifier
Device Under Test
Microscope
Device Under Test
Measurement
Display
Microscope

21.
Winning Metasurface Design
2 © Nokia 20162 © Nokia 2016 <Change information classification in footer>
Vibrating
surface
mm-wave
Ground
plane
SIDE view
TOP view
Structure of Vibrating reflective surface
Conductive
jig
Piezo actuators
d
d+Dd

22.
Winning Metasurface Design
2 © Nokia 20162 © Nokia 2016 <Change information classification in footer>
Vibrating
surface
mm-wave
Ground
plane
SIDE view
TOP view
Structure of Vibrating reflective surface
Conductive
jig
Piezo actuators
d
d+Dd
Fabrication details in paper

23.
Metasurface In Action

24.
READER
CHANNEL
METASURFACE
Transmitter
Receiver
Transmitted Signal
Reflected Signal
Physical
Oscillations
KinPhy
Consists of 2 components + channel
- metasurface
- radar reader

25.
Radar
Shine mm-wave onto remote metasurface
Decode kinetically backscattered signal READER
CHANNEL
METASURFACE
Transmitter
Receiver
Transmitted Signal
Reflected Signal
Physical
Oscillations

26.
Radar
Shine mm-wave onto remote metasurface
Decode kinetically backscattered signal
FFT CFAR Peak Detection
raw radar
ADC
Fast-Time
FFT CFAR Peak Detection
Slow-Time
Preprocessing
PSD Integration
DOA MIXER DESPREADER Peak Detection
DSSS Demod
coded surface info:
- range
- range rate
- angle
- KSSI
range info
range rate info
0 10 20 30 40
lag (sec)
20
30
40
50
60
70
despreader(dB)
20 40 60 80 100
freq. (Hz)
-20
0
20
40
60
PSD(dB/Hz)
0 50 100 150 200 250
range bin
20
40
60
80
power(dB)
0 200 400 600 800 1000
range rate bin
20
40
60
80
100
120
140
power(dB)
(a) overall pipeline
(b.i)
(b) output
(b.ii) (b.iii)
(b.iv)

27.
Radar
Shine mm-wave onto remote metasurface
Decode kinetically backscattered signal
FFT CFAR Peak Detection
raw radar
ADC
Fast-Time
FFT CFAR Peak Detection
Slow-Time
Preprocessing
PSD Integration
DOA MIXER DESPREADER Peak Detection
DSSS Demod
coded surface info:
- range
- range rate
- angle
- KSSI
range info
range rate info
0 10 20 30 40
lag (sec)
20
30
40
50
60
70
despreader(dB)
20 40 60 80 100
freq. (Hz)
-20
0
20
40
60
PSD(dB/Hz)
0 50 100 150 200 250
range bin
20
40
60
80
power(dB)
0 200 400 600 800 1000
range rate bin
20
40
60
80
100
120
140
power(dB)
(a) overall pipeline
(b.i)
(b) output
(b.ii) (b.iii)
(b.iv)
Signal processing details in paper

28.
Implementation
In-house metasurface

29.
Implementation
In-house metasurface Off-the-shelf Radar from Texas Instruments
Configurable FMCW signalling
DAQ for raw data
10 dBm Tx power

30.
Evaluation
5m
Radar Metasurface
•Distance: d ∈ [1, 3, 5]m
•Bandwidth: [1.75, 3.5] GHz
•Gold code: [63, 127, 511] chips
•Yaw: [0, ±5, ±10, ±22.5, ±45, ±67.5, 90, 180]°
•Pitch: [0, ±22.5, ±45, ±67.5, 90]°
Dataset

31.
Results - Detection Accuracy
1.75 GHz 3.5 GHz
Investigate effects of distance, axial alignment, coding gain, and bandwidth

32.
Results - Detection Accuracy
1.75 GHz 3.5 GHz
Finding 1: coding gain compensates for distance and axial misalignment
losses

33.
Results - Detection Accuracy
1.75 GHz 3.5 GHz
Finding 2: Using less bandwidth enhances performance

34.
Results - Kinetic Signal Strength Indicator (KSSI)
Investigate KSSI in yaw and pitch as a function of distance and coding gain

35.
Results - Kinetic Signal Strength Indicator (KSSI)
Finding 3: Decent KSSI even when metasurface was i.e. facing away
from radar
180o

36.
Results - NLOS Detection
Finding 4: Many successful demodulations were possible from NLOS
reflections in a cluttered office environment, originating from as far as
12 metres away

37.
[II] Provocations & Applications

38.
KinPhy Applications

39.
Beam alignment
KinPhy Applications
[Abari & Hassanieh SigComm ’18]

40.
KinPhy Applications
Surface
sequence A
Surface
sequence C
…
1 1 1 0 1
1 0 1 1 0
time
time
Multi-metasurface KinPhy
Metasurface
sequence A
Metasurface
sequence B
Metasurface
sequence C
BeamA
Beam
BBeam
C
Node
2
Transmitted
Reflected
Node 1Beam alignment at physical-layer ?

41.
KinPhy Applications
Security & Privacy

42.
Current Spontaneous Authentication Is “Clunky”
Apple echo-system example: Screen Mirroring

43.
Current Spontaneous Authentication Is “Clunky”
Apple echo-system example: Screen Mirroring
(1)

44.
Current Spontaneous Authentication Is “Clunky”
Apple echo-system example: Screen Mirroring
(1) (2)

45.
Current Spontaneous Authentication Is “Clunky”
Apple echo-system example: Screen Mirroring
(1) (2) (3)

46.
Current Spontaneous Authentication Is “Clunky”
Apple echo-system example: Screen Mirroring
(1) (2) (3) (4)

47.
KinPhy-Enabled Spontaneous Authentication

48.
Conclusions
KinPhy is a novel “mechanical” backscatter channel
Maps onto commodity tri-band routers [capable of communications sensing] &
modern haptics.
Empirically shown to work indoors under realistic conditions and assumptions
Affords particular benefits to spontaneous secure interaction
Physically oscillating
metasurfaces
Trans’d
Refl’d
Transmitted
Reflected
Node 2
Node N
Node 1
…

49.
Cheers
alloulah [@] outlook . com