Connectivity-Aware Routing (CAR) in Vehicular Ad Hoc Networks Valery Naumov & Thomas R. Gross ETH Zurich, Switzerland IEEE INFOCOM 2007

Outline Introduction Related Works (GPSR) Connection-Aware Routing (CAR) Simulation Conclusion

Introduction Vehicular ad hoc networks (VANETs) using 802.11-based WLAN technology have recently received considerable attention in many projects Several geographic routing (GR) protocols use an idealized mechanism such that for every originated data packet the true position of the destination is known

Introduction Another problem is that, all of the GR protocols do not take into account if a path between source and destination is populated. This paper presents a novel position-based routing scheme called Connectivity-Aware Routing (CAR) to address these kind of problems

Outline Introduction Related Works (GPSR) Connection-Aware Routing (CAR) Simulation Conclusion

Greedy Perimeter Stateless Routing

Greedy Perimeter Stateless Routing Perimeter Mode

Greedy Perimeter Stateless Routing

Outline Introduction Related Works (GPSR) Connection-Aware Routing (CAR) Simulation Conclusion

Connection-Aware Routing (CAR) The CAR protocol consists of four main parts: (1) destination location and path discovery (2) data packet forwarding along the found path (3) path maintenance with the help of guards (4) error recovery

Destination location discovery A source broadcast a path discovery (PD) Each node forwarding the PD updates some entries of PD packets If two velocity vectors’angle > 18°, anchor is set.

Greedy forwarding over the anchored path A neighbor that is closer to the next anchor point is chosen (greedy) , instead of destination.

Path maintenance If an end node (source or destination) changes position or direction, standing guard will be activated to maintain the path.

Path maintenance If end node changes direction against the direction of communication, traveling guard will be activated. A traveling guard runs as end node’s old direction and speed, and reroute the packets to the destination.

Path maintenance

Routing error recovery The reason for routing error A temporary gap between vehicles (1) Timeout algorithm When a node detects a gap – buffer the packets (2) Walk-around error recovery When Timeout algorithm fail , do location discovery Whether the location discovery is successful, the result will be reported to the source node.

Outline Introduction Related Works (GPSR) Connection-Aware Routing (CAR) Simulation Conclusion

Simulation Scenarios Traffic density City Highway Low – less than 15 vehicles/km Medium – 30-40 vehicles/km High – more then 50 vehicles/km

Simulation- Packet Delivery Ratio

Simulation- Average data packet delay

Simulation- Routing overhead

Outline Introduction Related Works (GPSR) Connection-Aware Routing (CAR) Simulation Conclusion

Conclusion Address the populated problem about paths. Path discovery & Anchor points Path maintenance with guards Error recovery Higher performance and lower routing overhead than GPSR