Transcript Document 7535133

Antenna Actuation
for Radio Telemetry
in Remote Sensor Networks
University of California at Los Angeles
David Browne, Vishwa Goudar, Henrik Borgstrom,
Michael Fitz, William Kaiser
UnWiReD Lab
UCLA Wireless Research and Development
IEEE Vehicular Technology Conference
Los Angeles, September 27-29 2004
Remote Sensor Networks
Three characteristics:
1. Nodes deployed sparsely over large geographic regions
2. Nodes gather local data on a natural phenomenon
3. Nodes need to communicate sensor data
Example: UCLA Broadband Seismic Network Array
(Thanks to
Igor Stubailo
and John Propst
for graphics.)
UnWiReD Lab
UCLA Wireless Research and Development
Slide 2
Remote Sensor Networks
Goal:
Enable telemetry of sensor data between nodes
Known solution:
Radio telemetry over omni-directional or sector antenna
Benefits:
• ad hoc deployment
• self assembling
• self healing
Limitations:
• Poor range
• Low energy efficiency
Better solution:
Highly-directional antennas with rotational actuation
UnWiReD Lab
UCLA Wireless Research and Development
Slide 3
Benefits of Directional Antenna
Measured Path Loss: 40dB/decade is typical
Range improvement:
• Omnidirectional: 80dB loss @ 130m
• 15dBi Directional: 80dB loss @ 750m
Efficiency improvement:
• A link over 15dBi antennas is 1000x more energy efficient
azimuth
UnWiReD Lab
UCLA Wireless Research and Development
azimuth & elevation
Slide 4
Actuated Network Assembly
Initial antenna
orientation
4
1
3
2
5
Antenna orientation
after articulation
4
1
3
2
UnWiReD Lab
UCLA Wireless Research and Development
5
Slide 5
The First Contact Problem
Node 1
Node 2
90°
270°
2
1
180°
0°
16
0°
320
270°
180°
Missing information:
• Direction to other nodes.
• Search coordination
90°
d
Energy Considerations:
• search depletes energy
• global vs. local maxima
150
-40
100
Node 1 (RX) Heading, 1
-50
50
-60
0
Q: How to shorten the first
contact search?
-70
-50
-80
-100
-90
-150
-100
-150
-100
-50
0
50
Node 2 (TX) Heading, 2
UnWiReD Lab
UCLA Wireless Research and Development
100
A: coordination & geolocation.
150
Slide 6
Wideband vs. Narrowband Radios
802.11b Radio:
• 2.44 GHz
• 20MHz Bandwidth
• 100m range (omni)
UnWiReD Lab
UCLA Wireless Research and Development
UCLA Narrowband Radio:
• 220 MHz
• 4 kHz
• 2 mile urban range (omni)
Slide 7
Search Strategies
Node 1
Actuator
Laptop
Node 2
antenna
Test
Environment
802.11b
Tranceiver
antenna
802.11b
Tranceiver
Actuator
Laptop
Search Coordination
GPS
Radio
Long Range
Tranceiver
UnWiReD Lab
UCLA Wireless Research and Development
Link
Slide 8
Long Range
Tranceiver
GPS
Radio
Field Test Results
5900
Strategy A (no LR, no GPS)
4900
1000
Acquisition Time (s)
800
Strategy B (with LR, no GPS)
Strategy C (no LR, with GPS)
Strategy D (with LR, with GPS)
600
400
200
0
0
20
40
60
Range (m)
UnWiReD Lab
UCLA Wireless Research and Development
Slide 9
80
100
Field Test Conclusions
Blind vs. Geolocation and/or Coordination
 reduced search duration from 1.5 hours to 15min
Coordination only
 search times are independent of range.
Geolocation only
 excellent short range (0m – 500m) search times (10s)
 exponentially deteriorating performance after 500m
Coordination & Geolocation
excellent range independent search times (10s)
UnWiReD Lab
UCLA Wireless Research and Development
Slide 10
Conclusions on Directional Antenna Actuation
Benefits common with omni/sector solutions
• ad hoc deployment
• self assembly
• self healing
Advantages over omni/sector solutions:
• range
• energy efficiency
Disadvantage: latency due to actuation
• latency due to actuation
 Importance of minimizing search time.
UnWiReD Lab
UCLA Wireless Research and Development
Slide 11
What’s Next
Node 1
Node 2
Actuator
Test
Environment
antenna
antenna
802.11b
Tranceiver
Laptop
Actuator
802.11b
Tranceiver
Laptop
Search Coordination
Long Range
Tranceiver
GPS
Radio
Long Range
Tranceiver
Link
GPS
Radio
Directional Channel
Sounder TX
Directional Channel
Sounder RX
Actuator 1
Linux
Computer
High Rate Data Bus
Serial Port
Controller
RS-232
GPS
Actuator
Directional
Antenna
Directional
Antenna RF (GHz)
UCLA
Wideband
Radio
RX IF
(MHz)
Parallel
Port
RF (GHz)
RS-232
Sweeping
Tone
Generator
RS-232
RS-232
GPS
RS-232
RS-232
Long Range
Radio
UnWiReD Lab
UCLA Wireless Research and Development
Omni-directional
Antenna
Omni-directional
Antenna
Slide 12
Narrowband
Radio
RS-232
Data
Acquisition
Board
High Rate Data Bus
Linux
Computer
High Rate Data Bus
Serial Port
Controller
End of Presentation
Questions and Comments
UnWiReD Lab
UCLA Wireless Research and Development
Slide 13
Search Algorithms
A. Blind Search (baseline)
• 802.11b radios search for
>threshold coordinate.
• Exhaustive search for the global
maximum.
• Upper bounds all strategies.
B. Coordinated Search
• Coordination via LR radios.
• Nodes begin 180º out of phase.
• Nodes complete one rotation.
• Link guaranteed within one
rotation.
• Lower bound for coordination.
C. Blind Search & Geolocation
• Random walk (speed & dwell).
• 802.11b radios search for
>threshold coordinate.
• GPS coordinates exchanged
over 802.11 radios for LOS
alignment.
D. Coordination & Geololation
• GPS coordinates exchanged over
LR radios .
• Immediate LOS alignment.
UnWiReD Lab
UCLA Wireless Research and Development
Slide 14
(# Coordinates > Threshold) vs. Range
1400
-40
1200
100
-50
1000
Node 1 (RX) Heading, 1
Number of coordinates above -85dB
150
800
600
400
50
-60
0
-70
-50
-80
-100
-90
200
-150
0
0
100
200
300
400
500
Range (m)
UnWiReD Lab
UCLA Wireless Research and Development
600
700
800
900
-100
-150
Slide 15
-100
-50
0
50
Node 2 (TX) Heading, 2
100
150
Strategy C Simulation
-80
150
-90
-100
100
Node 1 (RX)
Heading,
-120
o
0
+
-130
-50
-140
-150
-100
-160
-150
-170
-200
-200
-150
+ Start
UnWiReD Lab
UCLA Wireless Research and Development
-100
-50
0
Node 2 (TX)
Heading,
50

100
2
o Stop
Step
Slide 16
150
200
Path Gain
(dB)

1
-110
50
The Link Search Space
Simulated Link Search Space
Measured Link Search Space
Transmitter
Receiver
Actuator
RX
Spectrum
Analyzer
Laptop
Radio
Channel
TX
Actuator
2.4GHz Tone
Generator
Laptop
150
-40
150
-40
-50
100
-50
50
-60
0
-70
-50
-80
50
Node 1 (RX) Direction, 1
Node 1 (RX) Heading, 1
100
-60
0
-70
-50
-80
-100
-100
-90
-150
-100
-150
-100
-50
0
50
Node 2 (TX) Heading, 2
UnWiReD Lab
UCLA Wireless Research and Development
100
-90
-150
-100
-150
150
Slide 17
-100
-50
0
50
100
Node 2 (TX) Direction,2
150