Avaliação de desempenho de redes veiculares em condições adversas

Abstract

Vehicular Ad-hoc Networks (VANETs) are part of Intelligent Transportation Systems (ITS) and have been developed to enable communication between vehicles, as well as providing safety and comfort to drivers and passengers. Because of the high mobility, extremely dynamic topology, and the amount of applications these networks must support, there are still many challenges to be overcome and many assessments to be made. Different surveys have already evaluated the performance of VANETs, however, most of them are not realistic. As these networks are usually formed by several vehicles, a test in the real world is very expensive and timeconsuming. Therefore, most of the researches use simulators, which allow the rapid and inexpensive evaluation of protocols and applications. To make the results reliable, the scenarios of the simulations should reflect real-world conditions. However, because they are controllable by the user, they generally consider only favorable environments for the operation of VANETs, that is, they do not consider environments with adverse conditions (those that are detrimental to the proper functioning of the network), which are also frequent in vehicular communications. Therefore, this work proposes to conduct performance evaluations, through simulations, in vehicular networks with adverse conditions. For this, several adverse scenarios were considered, among them: vehicles transmitting high rates of data (up to 256 messages/s); vehicles transmitting large volumes of data (messages up to 4096 bytes in size); environments with low density (up to 5 vehicles per ); environments with high density (up to 400 vehicles per ); environments with reduced speed (1 km/h); environments with high speed (150 km/h). All scenarios were tested with the AODV, AOMDV, DSR and DSDV routing protocols, with the UDP and TCP transport protocols, and with the CBR traffic generation application. The simulations were performed using the Vanetmobisim and NS-2 simulators and the performance metrics evaluated were: delivery rate, routing overhead, delay and throughput. The results of the simulations demonstrate, among other conclusions, that the AODV/UDP and DSR/TCP sets presented the best results for the delivery rate in most cases.