A stochastic traffic modeling approach for 802.11p VANET broadcasting performance evaluation

The safety and commercial benefits of Intelligent Transportation System (ITS) raised interests towards inter-vehicle networking technologies such as Vehicular Ad-hoc Network (VANET). Being an approved standard for wireless access in vehicular environments, IEEE 802.11p attracts a lot of research attentions, especially on its broadcasting performance. However, most of the previous network performance models paid little attention to vehicle distribution, or simply assumed homogeneous car distribution. It is obvious that vehicles are distributed non-homogeneously along a road segment due to traffic controls and speed limits at different portions of the road. In light of the inadequacy, we present in this paper an original methodology to study the performance of 802.11p VANETs with practical vehicle distribution in urban environment. An empirically verified stochastic traffic model is adopted, which incorporates the effect of urban settings (such as traffic lights) on car distribution and generates practical car density profiles. Based on the knowledge of car density at each location from the traffic model, the 802.11p broadcasting model is developed and a new metric, Broadcasting Performance Index (BPI), is introduced to better characterize the broadcasting performance and packet collision probability in VANETs. Furthermore, the analytical closed form for BPI is derived and its accuracy is confirmed with extensive simulation. In general, our results demonstrate the applicability of the proposed methodology on modeling protocol performance, and shed insights into the performance analysis of other communication protocols and network configurations in urban vehicular networks.