Irresponsible Forwarding

In a self-organizing traffic information system, vehicles share and distribute the traffic information by rebroadcasting a received information packet to their neighbors. However, it is inefficient to let every vehicle rebroadcast the information packet, since the redundant packets waste the valuable (finite) radio channel bandwidth. Reducing the number of redundant packets, while still ensuring good coverage and reachability, is one of the main objectives in multi-hop broadcasting. In this paper, we propose a new probabilistic-based rebroadcast scheme, denoted as Irresponsible Forwarding, where each vehicle rebroadcasts a received information on the basis of (i) its distance from the source and (ii) the density of its neighbors. The key idea is that a node implicitly evaluates the probability that there is another node which can rebroadcast more successfully: if this probability is sufficiently high, then the node "irresponsibly" does not rebroadcast Unlike the other existing probability assignment schemes, our scheme also takes the statistical distribution of the vehicles on the road into consideration. Moreover, it will be shown that, for sufficiently large values of the vehicle spatial density, the average number of rebroadcast packets can be regulated by properly tuning a single parameter.