Adaptation of topology-based routing protocols for data gathering applications in VANETs

The use of VANETs for data gathering applications imply that vehicles are not only able to generate data but also to forward it from others towards an access point (AP). Given the mobility characteristics of vehicles and the difficult propagation conditions of urban scenarios, it is commonly stated that topology-based routing solutions are less efficient than geographic-based routing solutions. However, these statements refer to generic vehicular communications, ignoring specific characteristics of data gathering scenarios. In this work, two existing routing protocols that prior to forwarding data, set a path from each vehicle towards the AP are adapted for data gathering applications. While the existence of a path reduces the number of ineffective retransmissions and the delay, it also increases the overhead, and therefore the presented protocols were adapted to improve the overall performance. Aiming to correctly evaluate the routing protocols, simulations are launched using a realistic trace from the city of Cologne. The results obtained show that it is possible to limit the overhead associated to topology updates, outperforming geographic-based solutions.