12-01-2012, 12:38 PM
VEHICULAR AD HOC NETWORKS
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What is a VANET ?
Ad hoc network composed of vehicles
Individual nodes different from traditional wireless nodes
No power constraint
Nodes mostly mobile
Complements existing infrastructure
Extends existing infrastructure
Medium Access Control
Dedicated Short Range Communication (DSRC)
FCC regulated 5.9 GHz
10 MHz channels
1 control, 6 service
MAC similar to 802.11, i.e., CSMA/CA
OFDM used in PHY
Speeds up to 120 mph
Up to 1000 m transmission range
Applications
Traffic control
Automatic speed limit enforcement
Rerouting in traffic congestion
Safety
Notification of accident up ahead
Decentralized 911 service
Prioritized over non-safety applications
Extended communication
Infotainment
Security Aspects
Somewhat similar to sensor networks
Sensors might report “incorrect” data
- Undetected error
- Detected error
- Corrected error
Data Delivery
Opportunistic forwarding
- Disconnection possible
Geographic forwarding
Trajectory based forwarding
- A coordinate system is assumed
-Nodes know position in this coordinate system
- Route is a trajectory in this coordinate system
