Performance of MAC protocols in linear VANETs under different attenuation and fading conditions

Vehicular Ad hoc networks (VANETs) are an important example of Mobile Ad hoc Networks (MANETs) because they can save lives by improving safety on our road networks. They are difficult to design however due their inherent characteristics e.g., quickly changing topology, node density and relative speeds of vehicles. These characteristics also make current wireless Media Access Control (MAC) protocols unsuitable for use in VANETs without modifications. In this paper we study the performance of these protocols to see how they can be tuned to design a VANET with optimal network throughput. We do a simulation study of two popular MAC schemes (Aloha and CSMA) in a linear VANET and analyze them in terms of density of progress of the transmissions under different attenuation and fading conditions. The results show how network performance deteriorates with changes in the conditions and how we can improve it by tuning the MAC protocols. The results presented in this paper can be useful for the design and optimal tuning of VANETs in varying network conditions (attenuation, fading and noise).