Disseminating Traffic Data
over Vehicles on Road
 A Preliminary Proposal to the
ITA Demo Project
Presented by Bo Xu
Outline
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Objective
Demo Scenarios
Possible Technical Approaches
Steps
Relevant Projects
Objective
• Build a demo system that enables disseminating
traffic data over a fleet of vehicles, where traffic
data includes
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GPS locations of vehicles
Speeds of vehicles
Still images of traffic situation
Video clips of traffic situation
• The demo system serves as a seed into which
other CTS research may be integrated
Demo Scenario 1: Disseminating
GPS Locations and Speeds
• A fleet (e.g., 20) of vehicles drive along a highway.
• Each vehicle samples its location and speed periodically
and disseminates them to the other vehicles in the fleet.
• Each vehicles reconstructs a global view of the fleet
45, 1.2
distance
speed
40, 0.9
50, 0.6
54, 0.3
B
A
C
D
Demo Scenario 2: Disseminating
Still Images
• Each vehicle takes pictures of the traffic ahead
periodically and disseminates along with the location and
speed information.
• Picture and speed provide better perception of traffic
condition
Picture taken by A
45 MPH
1.2 miles
B
A
C
D
Demo Scenario 3: Disseminating
Video Clips
• Each vehicle shoots and disseminates the video of the
traffic ahead
Video shot by A
45 MPH
1.2 miles
B
A
C
D
Possible Technical Approaches
• Mobile Peer-to-peer (P2P)
– Each vehicle is equipped with a short-range wireless
device such as an 802.11-enabled PDA.
– Traffic data is transitively disseminated among vehicles
– Being studied in our research
Picture taken by A
45 MPH
1.2 miles
B
A
C
D
Mobile P2P Dissemination
• Two paradigms
– Stateful
• A routing structure is imposed and maintained among
vehicles
• May be ineffective in a highly mobile or partitionable
environment
– Stateless
• The intermediate vehicles save data and later (as new
neighbors are discovered) transfer the data
• Also called stateless gossiping, epidemic, or store-andforward dissemination
Mobile P2P Dissemination (Cont’d)
• Decisions to make at each vehicle
– When to transmit
• Upon discovering new neighbors
• Upon receiving new data
• Periodic transmitting
– How much to transmit
• Maximizing wireless throughput
– What to transmit
• Ranking based on spatio-temporal relevance
• Adjustment: If two pieces of data pertain to vehicles close to
each other, then only one piece needs to be transmitted
• Ranked Store-and-forward (studied in our ICDCS’06,
ICWMC’07, MDM’07, TAAS papers)
Risk of Mobile P2P
• Can mobile P2P provide enough
throughput for video transmission for multihops?
– Existing study has shown that the throughput
of mobile P2P networks decreases
dramatically as the number of hops increases.
– In our case, in order to see the real-time traffic
condition one mile ahead, 16 hops are
needed
Alternative: Central Server Solution
• Each vehicle transmits its video clips to a central server via the
cellular infrastructure. The video clips are downloaded by other
vehicles via the cellular infrastructure.
Video shot by A
ITA Server
at UIC
45 MPH
1.2 miles
B
A
C
D
Steps
• Test with two pedestrians
• Test with a group of pedestrians. From this
test we will know whether a mobile P2P
network can provide enough throughput
for video dissemination for multi-hops
• Test with two vehicles
• Test with a fleet of vehicles
Collecting Empirical Data
• Use the demo system to generate traces of
vehicles and to collect empirical data about
inter-vehicle communication.
– What is the transmission range of 802.11 in a highway
environment
– What is the wireless capacity and how it depends on
the speed and density of the communicating vehicles
as well as their transmission size and frequency
– The vehicle traces and the empirical data can be
used as a simulation test-bed for our future study on
vehicular networks.
Devices
• Camera phone+802.11+GPS
• Interface with vehicle on-board computer
– OBD (On-Board Diagnostics)
– Obtain speed, brake position, ABS, fuel
pressure, throttle position
Relevant Projects
• Three types of applications that involve inter-vehicle
communication
– Information and warning functions
• Dissemination of road information (including incidents, congestion,
surface condition, etc.) to vehicles distant from the subjected site.
• Our demo project mainly belongs to this type
– Communication-based longitudinal control
• Exploiting the “look-through” capability of IVC to help avoiding
accidents and platooning vehicles for improving road capacity.
– Co-operative assistance systems
• Coordinating vehicles at critical points such as blind crossings (a
crossing without light control) and highway entries
Information and warning functions
• No real system implemented yet
• Grassroots, Rutgers University, disseminating travel
time
• Collaborative Content Distribution for Vehicular Ad Hoc
Networks, UCBerkely
– Propagating data along a highway using the network coding
technique
– Comparison/integrating with ranked store-and-forward?
Problem: An infostation is disseminating data to all the vehicles
that are traveling in the same direction along the highway
Communication-based longitudinal
control
• TrafficView, Rutgers University,
http://discolab.rutgers.edu/traffic/index.htm
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Exchange GPS locations/speeds among vehicles
802.11 based
Demo with 4 vehicles seemly within a single hop
Demo video available at
http://discolab.rutgers.edu/traffic/tvdemo.html
Co-operative assistance systems
• CPF (Collaborative Perception Framework),
INRIA, France
– Sensor fusion to determine orientation and location of
a vehicle
• Speedometer, Gyrometer (angular speed), GPS
– 802.11 based
– Demo with 2 vehicles and one roadside facility within
a single hop
– Demo video 1
– Demo video 2
Question:
How do you see your research
integrating into the proposed seedITA?
Questions/Comments?