Throughput and Fairness Analysis of 802.11-Based Vehicle-to-Infrastructure Data Transfers

The performance of vehicular Internet access using roadside 802.11-based APs has been extensively studied in the literature. However, much less attention has been dedicated to analysing the maximum achievable throughput when multiple vehicles simultaneously share the bandwidth of the same roadside AP in a given mobility scenario. To fill such a gap, in this paper we develop an analytical framework to quantify the total amount of data transferred by a vehicle that drives through the coverage area of a roadside 802.11-based AP. The distinctive aspects of our analysis are the following: (i) it considers heterogeneous vehicular environments where vehicles may have different mobility characteristics; and (ii) it accurately takes into account critical traffic parameters, such as road capacity and vehicle density, when modelling MAC layer capacity. Our model is able to accurately characterize the unfairness that may arise due to differences in the relative speed of vehicles. In addition, our analysis and the supporting simulation results are useful to explain the complex relation ship that exists between the upload capacity per vehicle, the macroscopic characteristics of the traffic stream, the vehicular mobility model, and the 802.11 channel access rules.