Multichannel communications in vehicular Ad Hoc networks: a survey

Vehicular ad hoc networks are the key to provisioning safety-critical and commercial services on the road. Multiple channels are assigned in the 5 GHz spectrum to support these services. In this article an overview of the multichannel architecture proposed by standardization bodies in the United States and Europe is presented. The main contribution is the identification of the open challenges for multichannel coordination, synchronization, and access. Discussions on related countermeasures, fully explored in neither the standards nor the scientific literature, aim to serve as guidelines for designers of future protocols and applications in vehicular environments.