Dead-Reckoning for Position-Based Forwarding on Highways

Position-Based Forwarding (PBF), i.e. greedy position-based packet forwarding using a beaconing-induced neighbor table, suffers from an always-outdated perception of neighbor positions, especially at low beaconing rates. However, betweenbeacon accuracy is likely to be improvable by the application of dead-reckoning strategies, the extrapolation of known position information. Especially in vehicular highway scenarios, where node movement is “very one-dimensional” and changes of direction are impossible, extrapolation seems to be useful. In this paper we study the effects of dead-reckoning strategies on the between-beacon position accuracy. To do this, we have carried out simulations to investigate the impact of different dead-reckoning strategies on protocol performance and cost and we explain the trade-offs between them. We conclude: In German highway scenarios, dead-reckoning enhanced PBF can achieve almost perfect packet delivery with beacon intervals of up to 6 seconds, whereas standard PBF loses a significant ratio of packets even at a beacon interval of 1 second. In general, we show results indicating that the application of dead-reckoning generates (a) less beaconing traffic with an equal or better perception of the neighbors’ positions and (b) less overall transmission cost caused by frequent packet retransmissions when using the same beaconing frequencies.