ABSTRACT
Abstract .......................................................................................................................................... 572 21.1 Introduction .......................................................................................................................... 572 21.2 Literature Review and Related Work .................................................................................... 573
21.2.1 VANET Simulation Challenges ................................................................................ 573 21.2.2 VANET Models, Tools, and Platforms ..................................................................... 574
21.2.2.1 Network Simulation Tools ......................................................................... 574 21.2.2.2 Trafc Simulation Tools ............................................................................ 575 21.2.2.3 Interlinking Tools....................................................................................... 576 21.2.2.4 VANET Simulation Tools .......................................................................... 576
21.2.3 Overview of IEEE 802.11 and 802.11p ..................................................................... 577 21.3 Alternatives to IEEE 802.11p for Vehicular Environments .................................................. 579 21.4 Simulation Requirements ..................................................................................................... 581
21.4.1 Network Simulation (OMNeT++) ............................................................................. 581 21.4.1.1 INETMANET ............................................................................................ 582 21.4.1.2 Scenario Denition Using NED Files ........................................................ 582 21.4.1.3 omnetpp.ini File ......................................................................................... 582
21.4.2 Trafc Simulation ..................................................................................................... 583 21.4.2.1 SUMO ........................................................................................................ 583
21.4.3 Trafc Control Interface ........................................................................................... 584 21.5 Case Study ............................................................................................................................ 584
21.5.1 Simulation Scenarios ................................................................................................ 584 21.5.1.1 Urban Scenario .......................................................................................... 584 21.5.1.2 Highway Scenario ...................................................................................... 584
21.5.2 Simulation Parameters and Metrics .......................................................................... 585 21.5.3 Urban ........................................................................................................................ 586 21.5.4 Highway .................................................................................................................... 589
21.6 Conclusions ........................................................................................................................... 590 Acknowledgments .......................................................................................................................... 590 References ...................................................................................................................................... 591
Vehicular ad hoc networks (VANETs) have attractive potential in order to reduce trafc jams and avoid transportation disasters. They are also able to provide infotainment services like web browsing, e-mail, or using social networks on the road. Achieving a well-designed medium access control (MAC) protocol is a challenging issue to improve communications efciency due to the dynamic nature of VANETs. The CSMA-based MAC protocol adopted by the IEEE 802.11p standard was selected as the best choice for the current generation of VANETs considering its availability, maturity, and cost. Despite these benets, the common problem in all IEEE 802.11-based protocols is scalability, exhibiting performance degradation in highly variable network scenarios. This chapter provides an overview of 802.11/802.11p, as well as alternatives presented by the research community to address the detected limitations in vehicular scenarios. In addition, performance evaluation results highlight the need for contention window (CW) adjustment schemes in order to avoid performance degradation, especially in dense and highly mobile scenarios. Realistic vehicular environment clearly affects the obtained results, so we tried to choose appropriate and realistic network and trafc simulators. In this chapter, we also explain why the simulator choice is a relevant issue, and how to properly congure simulation settings for vehicular environments. Analysis and simulation results using OMNeT++ in vehicular scenarios, including highway and urban scenarios, show that alternatives to 802.11p able to perform CW adjustments are able to improve the overall performance, even for high network density scenarios.
