a Broadcast protocol for vehicular ad-hoc networks

On the design of efficient broadcast protocols in wireless mobile networks

How communications work in vehicular ad hoc networks?

A Vehicular Ad hoc Network (VANET) is a collection of mobile vehicles communicating through wireless connections. In such a network, each participating vehicle acts simultaneously as a node and as a wireless router, and has a limited coverage area delimiting the neighbors it can directly communicate with. The continuous movement of vehicles at different speeds and directions induces a highly dynamic network topology.

When a vehicule detect an event, i.e. an accident, it is important to share the information with all other vehicles. Then it must perform a broadcast communication, and each adjacent vehicule within the communication range of the transmitter may receive the message. To achieve a multi-hop broadcast, some vehicules have to relay incoming messages to allow a wide dissemination of the message. However a wireless communications consumes energy and may induce interferences and/or collisions with others concurrent wireless communications. here, more is less : if too many vehicules relay the communication, it propagation could be degraded.

The challenge

Any vehicule receiving a message has to take the decision to relay the message to the other nodes in its coverage area or not, with only few informations about the topology and 0 knowledge about what the other vehicules will do. This decision taking is the main point of broadcast methods and has a real impact on the efficiency of the dissemination strategy: : on the one hand, too many relay vehicules would quickly increase the number of collisions, leading to a saturation of the available bandwidth. On the other hand, if not enough retransmissions are performed the message may not be widely disseminated.

Here investigates the problem of building and evaluating autonomous and robust broadcasting protocols, which provide each node with the adequate strategy to determine if an incoming message has to be forwarded or not. To be efficient, these protocol must follow the autonomic computing paradigm: each node continuously updates its perception of the environment, adding new informations to adapt its decision process to the current situation.

Our results so far

Publications

  • 2 international journal in networks
  • 1 international conference in networks
  • 1 national conference (french)  in vehicular networks
  • 1 book chapter

People involved in the project

  • Wahabou Abdou
  • Benoit Darties
  • Nader Mbarek

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