This article proposes a slotted multichannel medium access control (SMMAC) protocol for VANETs to reduce CCH congestion, decrease RSU dependency, increase safety and data packet's reliability and improve fairness among vehicles. The main entity is the cluster head that not only notifies all the vehicles under the same cluster about the present state of service channel and future data transmissions but also imposes a condition on the maximum number of vehicles allowed inside a cluster. Controlled vehicle density reduces CCH collisions and as a result, it makes the protocol better in terms of packet delivery. To eliminate the inter-cluster hidden terminal problem, in the proposed algorithm, each cluster uses a service channel different from its neighboring cluster. Analyzing the system for both dense and sparse scenario it can be seen through simulation results that the proposed protocol performs much better in comparison to IEEE 802.11p with respect to Throughput, PDR and Delay.
Performance Analysis of the IEEE 802.11p Multichannel MAC Protocol in Vehicular Ad Hoc Networks