Performance Analysis of MANET Routing Protocols in Urban VANETs

Infrastructure-less communications between moving vehicles present emblematic challenges because of high node mobility and link volatility, which may harm the performances of different categories of emerging vehicular applications. In order to move data between vehicles that are not in direct communication range, several distributed routing protocols have been proposed and tested in vehicular networks, highlighting their strengths and weaknesses. Some previous works report disagreeing claims about routing protocol performances in similar vehicular scenarios. Therefore, in this work, we evaluate the performances in terms of Packet Delivery Ratio (PDR), packet delay, frame collision rate, and signaling rate of three well-known routing protocols (AODV, DSDV, and GPSR), simulating them in a realistic Manhattan scenario. Furthermore, we evaluate the impact of typical urban obstacles (e.g. buildings) on the considered performance metrics. We observed that, in the proposed urban scenario, AODV provided the best PDR, GPSR the best packet delay, and DSDV failed to provide satisfactory performances due to signaling-induced congestion. Simulations showed that considering the shadowing effects induced by the buildings in an urban scenario drastically changes the observed performances, i.e. reduces the frame collisions, decreases the PDR, and increases the packet delay.