Analysis of mobility speed impact on end-to-end communication performance in VANETs

Vehicular ad hoc networks (VANETs) have the potential to enable communication among vehicles either directly using a vehicle-to-vehicle (V2V) communication model or through a road side unit (RSU) while using a vehicle-to-infrastructure (V2I) communication model. In multi-hop messaging, end-to-end (E2E) communication delay and messages reachability are essential performance indicators for VANET applications, which in-fact are critical criteria for safety related messaging services. Several investigations have been carried on the impact of different cars mobility patterns on communication performance in VANETs and over different road networks. However, and to the best of our knowledge, a study aiming towards the analysis of mobility speed differences and their impact on E2E delays and messages reachability has not been thoroughly investigated for sender-oriented messaging schemes in VANETs. This paper evaluates the impact of speed differences among vehicles over the performance of two widely adopted classes of messaging schemes in VANETs, namely the furthest distance and link quality based schemes. The considered schemes are devised using a sender-oriented relay selection mechanism due to its efficient utilization of channel bandwidth. Simulation experiments are performed over two mobility speed scenarios with the first depicting a small speed difference among vehicles while the other depicting a large difference in speed. Analysis of the obtained results reveals the following major findings. In scenarios with small speed differences, the furthest distance scheme exhibits lower E2E delays when compared to link quality based scheme with a difference of up to 29.5 msec. Conversely, large differences in mobility speed have noticeable adverse effects on furthest distance scheme resulting into it having higher E2E delays as compared to link quality scheme, with a difference of up to 127.43 msec. In-terms of message reachability, the link quality scheme prominently outperforms the further distance scheme in both speed difference scenarios. Consequently, the link quality scheme shows robustness towards the adverse effects resulting from large differences in mobility speed while further distance scheme struggles to do so.