IEEE Vehicular Technology Conference

1
Antenna Actuation for Radio Telemetry in Remote
Sensor Networks

• University of California at Los AngelesDavid
  Browne, Vishwa Goudar, Henrik Borgstrom, Michael
  Fitz, William Kaiser

2
Remote Sensor Networks

• Three characteristics
• Nodes deployed sparsely over large geographic
  regions
• Nodes gather local data on a natural phenomenon
• Nodes need to communicate sensor data

Example UCLA Broadband Seismic Network Array
(Thanks to Igor Stubailo and John Propst for
graphics.)
3
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 solutionHighly-directional antennas with
rotational actuation
4
Benefits of Directional Antenna

• Measured Path Loss 40dB/decade is typical
• Range improvement
• Omnidirectional 80dB loss _at_ 130m
• 15dBi Directional 80dB loss _at_ 750m
• Efficiency improvement
• A link over 15dBi antennas is 1000x more energy
  efficient

azimuth
azimuth elevation
5
Actuated Network Assembly
Initial antenna orientation
Antenna orientation after articulation
6
The First Contact Problem

• Missing information
• Direction to other nodes.
• Search coordination
• Energy Considerations
• search depletes energy
• global vs. local maxima

Q How to shorten the first contact search? A
coordination geolocation.
7
Wideband vs. Narrowband Radios

• 802.11b Radio
• 2.44 GHz
• 20MHz Bandwidth
• 100m range (omni)

• UCLA Narrowband Radio
• 220 MHz
• 4 kHz
• 2 mile urban range (omni)

8
Search Strategies
9
Field Test Results
10
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)

11
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.

12
Whats Next
13
End of PresentationQuestions and Comments
14
Search Algorithms

• A. Blind Search (baseline)
• 802.11b radios search for gtthreshold 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 gtthreshold coordinate.
• GPS coordinates exchanged over 802.11 radios for
  LOS alignment.

• D. Coordination Geololation
• GPS coordinates exchanged over LR radios .
• Immediate LOS alignment.

15
( Coordinates gt Threshold) vs. Range
16
Strategy C Simulation
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The Link Search Space

• Simulated Link Search Space

Measured Link Search Space