A Survey of Media Access Control (MAC) Protocols for Vehicular Ad-hoc NETworks (VANETs)

Recent advances of various wireless communication technologies and the emergence of computationally rich vehicles are pushing Vehicular Ad-hoc NETwork (VANET) research to the forefront in academia and industry. A lot of research results have been published in various areas (such as routing, broadcasting, security, and others) of VANET in the last decade covering both Vehicle-to-Vehicle (V2V) and Vehicle-to-Infrastructure (V2I) scenarios. One specific area of VANET that still faces significant challenges is the design of reliable and robust Media Access Control (MAC) protocols for V2V communications. We present a survey of V2V MAC methods (including various VANET standards) that have been proposed for VANETs over the last few years. We focus on the benefits and limitations of the proposed MAC techniques as well as their ease of implementation in practice and future deployment. We also discuss some of the challenges that still need to be addressed to enable the implementation of highly efficient and high performance MAC protocols for V2V communications. Finally, we propose some innovative solutions that can be developed to address these challenges.