Disseminating Traffic Data over Vehicles on Road

A Preliminary Proposal to the ITA Demo Project

Presented by Bo Xu

Outline

• 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– 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

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speed

distance

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

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Demo Scenario 3: Disseminating Video Clips

• Each vehicle shoots and disseminates the video of the traffic ahead

Video shot by A

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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

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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-and-

forward 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 multi-hops?– 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.

ITA Serverat UIC

Video shot by A

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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– 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

Questions/Comments?

Question:How do you see your research

integrating into the proposed seed- ITA?