millimeterwave imaging sensor nets: a scalable 60-ghz
TRANSCRIPT
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WE2F-01
SMillimeterwave Imaging Sensor Nets: A Scalable 60-GHz Wireless Sensor
Network
Munkyo Seo*, B. Ananthasubramaniam, M. Rodwell and U. Madhow
El t i l d C t E i iElectrical and Computer EngineeringUniversity of California, Santa Barbara
CA 93106 USA
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CA 93106, USA
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Outline
• Motivation(1) A scalable, simplistic approach to the wireless sensor network(2) Exploit millimeter-wave frequencies
• Proposed Approach
• Collector System
• 60-GHz Passive sensors60 GHz Passive sensors
• Indoor Radio Experiment
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Wireless Sensor Networks (WSN)
• Goal: Distributed data collection & localization to obtain an information map D[x y z t]obtain an information map, D[x,y,z,t]
• Many scientific, industrial and military applicationsEnvironmental monitoring– Environmental monitoring,
– Wildlife research,– Seismic activity detection,Seismic activity detection,– remote sensing, – battle field surveillance, – border policing, – planetary exploration,
Body area network
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– Body-area network,– …
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Current WSN Practice• Data collection: Multi-hop based communication
– Low-power communication ☺– Not very suitable for large-scale networks
• Localization: Fixed ID code, GPS, acoustics, etc– Tends to make sensors costly, complex
4From Akyildiz et al, IEEE Comm. Mag., Aug. 2002
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Simplistic Sensor ApproachSensor with minimal functionalityMove all complexity to the collector
DATAdeltaf
sensor(1) Collector sweeps a beam(2) Sensors receive, modulate and transmit it back.(3) C ll t j i tl d t t d t & l ti sensor(3) Collector jointly detects data & location
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Simplistic Approach• Similarities with optical imaging & radar
• ScalabilityScalability– Communication grows linearly as # of sensors
• Built-in Localization• Built-in Localization– Range resolution by a wideband range-code– Angular resolution by a narrow beam– Angular resolution by a narrow beam
• Simplistic sensors (= low-cost, low-power)No communication among sensors– No communication among sensors
– No localization capability required.• Concerns
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• Concerns– Need line-of-sight, complex collector signal processing
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Exploit Millimeter-waves
NarrowBeamwidthWide Bandwidth
• Motivations:Higher angular resolution @ same antenna aperture
ooHPBWHPBW
eADφθλ
π 000,414 2 ==
– Higher angular resolution @ same antenna aperture– Higher range resolution @ same fractional BW– High data rate
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– High data rate– Unlicensed band @60GHz (BW>5GHz)
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Signal Processing Principle
• Localization– Goal: Find the most likely sensor locationGoal: Find the most likely sensor location.– How? 3-D matched filtering (M/F)
(1) Range correlation (Tx Range code)( ) g ( g )(2) Azimuth correlation (w/ AGF)(3) Elevation correlation (w/ AGF)(4) Fi d k!
Maximum-likelihooddetection
(4) Find a peak!Accuracy eventually limited by the received SNR
• Data Demodulation– Goal: Retrieve the local sensing data (1? 0?)
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Goal: Retrieve the local sensing data (1? 0?)– How? Track the peak
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Round-trip Radio Link
6~16dB/km @ 60-GHz band
( )2
22 eGDDDP R
dRXTXr λλ
α−
= ( )( )44 R
GDDDP downupsenssensRXTX
t πλλ
60-GHz
P D D D G 610BER@10kbps −=R
60-GHz +/- fdelta
7dBm 23dBi 40dBi 7dBi -3dB 25m (current prototype)25dBm 40dBi 40dBi 7dBi -3dB 200m (possible ext.)
tP TXD RXD sensD sensG max 10BER@10kbps, =R
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25dBm 40dBi 40dBi 7dBi 3dB 200m (possible ext.) 25dBm 40dBi 40dBi 7dBi 80dB 1,600m (“active” sensor)
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60-GHz Collector Block Diagram
Range code: 20-MHz PRBS (26-1) Single-chip= 7.5m,
Directivity= 40dB (2 deg)0.4m@R=10m
Steerable(azimuth, elevation)
g p ,Max. field size= 470m 4.0m@R=100m
WaveformSynthesizer x3 BPF
TX RF
Tx ANT
TX IF
PRBS(R=20MHz) D=23dBi
P=7dBm
20.166 GHz
TX-RF60.5 GHz
Rx ANT
S/GTX-IF
20.166 GHzP 7dBm
BPFDown-conv.
I/QDemod.
RX-RFRX-IF1RX-IF2
Oscilloscope
USB port
D=40dBi
10
60.5 GHz +50MHz4.25GHzRX IF2
900MHz
S/G900MHz
S/G18.766 GHz
Computer
USB port
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60-GHz Collector Transceiver
Rx Antenna (40dB)
Tx Antenna (23dB)
Remote controlledRemote-controlledPositioner (Az, El)
Transceiver board
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60-GHz Collector System
• Transceiver with all required instrumentsrequired instruments.
• Mounted on a mobile tcart.
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Measured Antenna Gain Function (AGF)
AGF = (TX ANT) (RX ANT)AGF (TX ANT) (RX ANT)= (23dB Horn) (40dB Cassegrain)
ude 1
Mag
nitu
0.5
M
-4 -3 -2 -1 0 1 2 3 40
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Azimuth, Elevation (degree)
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60-GHz Passive Sensor: Block Diagram
• Receive, modulate and re-radiate the beam
• Simplicity, low cost, robustness, etc
Baseband BPSK Modulator Open-slot Antenna
XTAL MS-to-SL¼ λfdelta= 50MHz
PIN di d (MA COM)
16-bitLocal
transition
¼ λ
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PIN diode (MA-COM)data¼
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60-GHz Passive Sensor: Considerations• Antenna
– Patch type? – Slot-type? – Open-slot type?
S b t t RO4003C• Substrate: RO4003C– 0.2mm, Er=3.38
Loss= 0 07dB/mm Q=20– Loss= 0.07dB/mm, Q=20• Standard low-cost PC-board
manufacturingmanufacturing– Min. line width/spacing =
5mil (125um)PIN diode(flip-chip)
15Size: 15mm x 10mm
– This favors high Z0 (=90ohm)
(flip chip)
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Modulator Impedanceab
60GHz65GHz ( )
i did tmodmod aVb Γ=
Bias ON(7mA) wavereflected:b
aveindident w:a
55GHz55GHz
60GHBias OFF
• Switches between two impedance states.
60GHz
65GHz
Bias OFF• ~180 degree relative
phase shift
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• BPSK Modulation
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Linearly-Tapered Open-Slot Antenna
Beam Pattern (7dBi)
HFSS
Beam Pattern (7dBi)
0dB-10dB
0Input Match
`
S(1
,1)) 0
-1020
dB(S
50 55 60 65 70
-20-30
17HPBW= 50 deg Freq (GHz)
50 55 60 65 70
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CMOS Passive Sensor (under fab.)
For low-power operation, CMOS integration i
L t (1 2)
is necessary
• 3-channel sensor (90-nm CMOS)
• dc power = 0 5~3uW
Layout (1mm2)
• dc power = 0.5~3uW
• Contains a BPSK modulator and l lt t ll dlow-power, voltage-controlled ring-oscillator
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• Flip-chip interface to ANT.
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Indoor Radio Experiment
sensor
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Received Power vs Range
Measured
dBm
)
MeasuredCalculated
41 R100-90-80
ower
(d
120-110-100
ved
Po
100
-120
101
Range (m)Rec
eiv
20
Range (m)
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Received Spectrum (RX-IF2)
0 0
Sensor OFF Sensor ON (~3m)
m)
-30
-20
-10
-30
-20-10
r (dB
m
-40
-30
-50
-40
-30
-50Pow
er
0.90 0.95 1.000.85 1.05 0.90 0.95 1.000.85 1.05
Freq. (GHz) Freq. (GHz)
21
q ( ) q ( )
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2-D Localization (M/F output)
Sweep 15.6 degStep= 0.6 deg
th
Single sensor
collectorradial
azim
utradial
Two sensors
22
collectorField size: 12x0.6 m2
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3-D Localization (M/F output)1.5 deg
0 5 deg
1.0 deg
0 deg
0.5 deg
El ti 0 deg
-0.5 deg
Elevation
-1.0 deg
23
-1.5 deg
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Data Demodulation
0
0.05
Reference PRBS-0.05
0
0.2
Reference PRBS
Received signal (I)-0.2
0
4
Received signal (I)
02Cross-correlation
1111 0001 001 0 111 00
-0.20
0.2Demodulated Data(10kbps)
1111 0001 001 0 111 00
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(10kbps)
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Summary
• Millimeter-wave wireless sensor networkLarge scale network w/ simplistic sensors– Large-scale network w/ simplistic sensors
• 60-GHz prototypeCollector– Collector
– PIN-diode based passive sensor– CMOS sensor (dc power: uW level)( p )
• Indoor radio experiment (<12m)– Data demodulation, 3D localization
• Next– uW CMOS sensor module
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– Large-scale radio experiment
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Thank you.
Questions?
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