EFFICIENT PARKING METER
MANAGEMENT SYSTEM
APRIL 26, 2006
STEPHEN DABIDEEN
YIZENIA MORA
ADVISORS: DR. ROCH GUERIN AND DR. SALEEM KASSAM
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Project Overview
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Assumptions
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Goal


City-wide wireless network
Parking meters with wireless and sensing capabilities
Get information about the meters’ status to a central
office
Objectives
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Design and implement communication protocol
Evaluation metrics: reliability and energy efficiency
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Central Station
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Statement of Problem
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Hardware
HARDWARE SETUP
PARKING METER
SENSOR
StarEast Board: 256 MB
RAM, 32 MB Flash,
Intel IXP425 Processor
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NL-2511-MP Prism 2.5
802.11b 200mW
miniPCI Wireless Card
RE05T-RSP
Antenna
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Hardware
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Head Meter Rotation
Goal: maximize the life of the system
 Transmitter with two levels of power
 Evenly distribute role of head meter
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• Option 1: fixed, predefined rotation
• Option 2: dynamically determined
rotation
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Pick the neighbor with highest battery level
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SAFE
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Goal
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Routing table
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A function of distance and reliability
Link Quality
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Local
Next hop
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Reliably and Efficiently route information to the
current head meter
Additive Increase Multiplicative decrease
Synchronization
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Store & Forward - single transmission per cycle
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Single-Path, Best-Effort Routing
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Data sent to best next hop and forwarded if
received
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Single-Path, Best-Effort Routing
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Packets lost due to collisions
Data loss cumulative
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Data Missed
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Multi-Transmission vs. Multi-Path
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Cost to send a packet of size b (b = 8):
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Energy = 1.9 * b + 266
Incremental cost

fixed cost
Cost to send x times:
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μJ
Energy = [1.9*b + 266]*x μJ
Cost to send through x Paths
• Since data piggy-backs on other packets:
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Energy = [1.9*b]*x + 266 μJ
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Full Multi-Path Routing
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Improves reliability
More paths = More energy
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Data Missed
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SAFE
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Synchronized Adaptive-Forwarding
Efficient Routing Protocol
Defines two types of paths
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Primary: Deterministic Best-Effort
Secondary: Probabilistic
Central station provides feedback
Adaptive-Forwarding: Probability Matrix
used to create secondary paths as needed
Synchronization
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Probabilistic Multi-Path Routing
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Reduces redundancy without sacrificing reliability
Uses multi-path only when needed
Primary Path
Secondary Path
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Probabilistic Multi-Path Routing
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Fewer Paths, Same level of reliability
Primary Path
Secondary Path
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The SAFE Probability Matrix
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3-D matrix
• Meter, Current Head Meter, Probability
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Determination
• Proactive Response
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Long term, time-of-day variations
• Reactive Response
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Temporary, unpredicted periods of unreliability
User chooses tradeoff
• Reliability vs. energy consumption
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Failure Recovery
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Loss of a head meter
• Transient loop => count to infinity
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Loss of a non-head meter
• Link Quality decreases
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Fragmentation
• Head meter in each group
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Defragmentation
• Single head meter
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Experimental Results
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Energy calculations for transmitting and receiving only
Group of 6 meters
Routing Type
Reliability
(% data loss)
Energy
Consumption
(J/cycle)
Best-Effort, Single Path
17.7
0.00600
SAFE: 10% response
3.7
0.00601
SAFE: 30% response
2.0
0.00606
Full Multi-Path
1.4
0.00617
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Conclusion
Goal and Objectives
 SAFE routing protocol

Two types of paths: primary and secondary
 Probabilities determined by the central
station
 Allows the user to trade reliability for energy
efficiency
 Designed for our project but easily
adaptable
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Acknowledgements
Prof. Roch Guerin (Advisor)
 Prof. Saleem Kassam (Advisor)
 Prof. CJ Taylor (Instructor)
 Prof. Ken Laker (Instructor)
 Mr. Phil Farnum (Instructor)
 Mr. Sid Deliwala (Gismos & Gadgets)
 TCOM Lab (StarEast Boards)
 CIS & ESE Departments (Funding)
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