Simulation is the tool of choice for the largescale performance evaluation of upcoming telecommunication networking paradigms that involve users aboard vehicles, such as next-generation cellular networks for vehicular access, pure vehicular ad hoc networks, and opportunistic disruption-tolerant networks. The single most distinguishing feature of vehicular networks simulation lies in the mobility of users, which is the result of the interaction of complex macroscopic and microscopic dynamics. Notwithstanding the improvements that vehicular mobility modeling has undergone during the past few years, no car traffic trace is available today that captures both macroscopic and microscopic behaviors of drivers over a large urban region, and does so with the level of detail required for networking research. In this paper, we present a realistic synthetic dataset of the car traffic over a typical 24 hours in a 400-km 2 region around the city of Köln, in Germany. We outline how our mobility description improves today's existing traces and show the potential impact that a comprehensive representation of vehicular mobility can have one the evaluation of networking technologies.
I. INTRODUCTIONVehicular environments have become increasingly attractive to the telecommunication networking research community over the last years. The reason is that cars are envisioned to become real communication hubs in the near future, thanks to the proliferation of smartphones and tablets, whose Internetconnection capabilities appear especially appealing to passengers aboard cars, as well as to the growing presence of radio interfaces on the vehicles themselves.Enhanced infrastructure-based systems, involving, e.g., the WiMAX and LTE-A technologies, and novel communication paradigms, such as, e.g., ad hoc and opportunistic networking, are being studied in order to accommodate the traffic generated and requested by forthcoming communicating vehicles. Most of these solution require large-scale performance evaluations that are not feasible through experimentation directly, due to costs and complexity. Simulation becomes thus the tool of choice to assess the quality such solutions.When simulating a vehicular network, particular attention must be paid to faithfully represent the unique dynamics of car mobility, characterized at a time by high-peak high-variance speeds, road topology-and road rules-constrained movements, and strong movement correlations over time and space. These properties are the result of macroscopic and microscopic car traffic dynamics, that need to be properly modeled in order to perform a simulative campaign whose results are credible.The relevance of mobility modeling in the simulation of vehicular networks is widely acknowledged, a factor that has led to a substantial progress in the quality of car movement traces for vehicular networking research. The simplistic stochastic models employed in early works [1], [2] have been replaced by