VehicletoVehicle Wireless Communication Protocols for Enhancing Highway Traffic Safety A Comparative

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Vehicle-to-Vehicle WirelessCommunication
Protocols forEnhancing Highway Traffic
Safety-A Comparative Study of Data
Dissemination Models for VANETs
Subir Biswas, Raymond Tatchikou, Francois
Dion - Tamer Nadeem, Pravin Shankar, Liviu Iftode

• Presentation Nick Frangiadakis

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Towards the future

• Cheap, embedded processors
• Cheap, embedded, small sensors
• Interconnected
• Mobile
• Ubiquitous Computing
• New services / applications

Wireless
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Towards the future

• A number of diverse (or not) technologies
• 802.11a/b/g/e/, GSM, UMTS, DSRC
• A number of different problems / applications /
  services
• ..
• An even greater number of solutions
• Exercise for the reader
• Each of the discussed technologies address best a
  different set of proposed applications
• Survival of the best Not always the case!
• Survival of the fittest Already deployed or
  cheaper or even supported from the largest company

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But this is a systems problem!

• Not so, or better not only
• Vast number of sensors? A lot of Data
• Distributed
• Possibly Mobile
• Queries about the data
• Most applications in fact are data-centric
• Internet could also be seen as a systems problem,
  but there is also e.g. Googles perspective

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VANETS
Vehicle-to-Vehicle WirelessCommunication
Protocols forEnhancing Highway Traffic Safety

• An application
• Thesis
• Traffic safety is an application that we WILL see
  in the near future.
• The technology used IS the one that will be
  discussed.
• This means that the technology discussed will be
  in place in the near future and will probably be
  used for more applications

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CCA Cooperative Collision Avoidance

• United States
• six million traffic accidents / year
• 2003
• 230 billion,
• 2,889,000 injuries,
• 42,643 deaths
• 5.850 to 5.925 GHz band allocated by US FCC

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CAC Application Examples

• Highway accidents
• Automatically adjusting cruise control
• Beacon for stopped cars / police
• Accidents from Red light / Stop violations
• In general Avoid human errors (90 of all traffic
  accidents)

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CCA Cooperative Collision Avoidance
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CCA Cooperative Collision Avoidance
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The general picture proposed national
infrastructure
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The general picture proposed national
infrastructure
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DSRC Dedicated Short Range Communication

• MAC
• De facto standard 802.11
• Stability problems (e.g. TDMA is very difficult)
• Packet Forwarding
• Time to establish connection is time lost
• MANET style not applicable (e.g. AODV does not
  work)
• Broadcast oriented, data-driven, packet
  forwarding based on geographic context

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Context aware packet forwarding

• Direction Aware Broadcast Forwarding
• Design targets (min Bandwidth, limit collisions,
  prioritize data, )
• What are the limits?
• Naïve Broadcast
• Intelligent Broadcast With Implicit
  Acknowledgment (?)
• Others ()

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Context aware packet forwarding Some numbers
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Context aware packet forwarding Some numbers
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Context aware packet forwarding Some numbers
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Context aware packet forwarding Some numbers
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Context aware packet forwarding Some numbers
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Some more Points

• With 80/kb/s/vehicle background traffic the
  protocol can still work
• Broadcast, intelligent with priorities
• Problem similar to Sensor Network problems for
  which there are models and bounds (e.g. The
  Capacity of Wireless Networks Piyush Gupta, P.R.
  Kumar, 1999 )
• Mobility Data Driven Priority
• (tx speed?)

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A Comparative Study of Data Dissemination Models
for VANETs Tamer Nadeem,Pravin Shankar, Liviu
Iftode

• VANETs enable a new class of applications that
  require time-critical responses (less than 50 ms)
  or very high data transfer rates (6-54 Mbps).
• The dissemination mechanism can either broadcast
  information to vehicles in all directions, or
  perform a directed broadcast restricting
  information about a vehicle to vehicles behind
  it.
• TrafficView

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Traffic View

• GPS, OBD, Stored maps etc (OBD On Board
  Diagnosis)
• Data aggregation, Periodically broadcast all
  stored data.
• Prototype / evaluation of simulation in ns2
• Without loss of generality, we assume vehicles
  move on bidirectional straight roads with
  multiple lanes in each direction

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Dissemination models
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Analysis

• Latency time (L) is defined as the time needed to
  propagate generated data between two vehicles
  positioned D meters from each other.
• Broadcast utilization (U) is defined as the
  percentage of the newly covered area by the
  current broadcast, which is not covered by any
  previous broadcast of the same data, to the total
  area covered by a broadcast.

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Analysis

• Latency time (L) is defined as the time needed to
  propagate generated data between two vehicles
  positioned D meters from each other.
• Broadcast utilization (U) is defined as the
  percentage of the newly covered area by the
  current broadcast, which is not covered by any
  previous broadcast of the same data, to the total
  area covered by a broadcast.

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Simulation

• Latency Time
• Utilization rate
• Knowledge Percentage For each region, the
  percentage of the known vehicles in a region by
  the current vehicle
• Accuracy The average error in estimating the
  position of vehicles in a region

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Simulation
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Other points

• Flooding is not good either
• Model ?
• Metrics ?
• Limits ?
• Applications!
• Hybrid Models?

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Thank you

• Comments ?
• Questions ?