Cluster-based multi-channel communications protocols in vehicle ad hoc networks

The dedicated short range communications (DSRC) standard equipped with seven channels is designated for intelligent transportation system (ITS) applications to improve the driving safety and support networking services among moving vehicles. Making best use of the DSRC multichannel architecture, we propose a cluster-based multichannel communications scheme, which integrates the clustering with contention-free/contention-based MAC protocols. In our proposed scheme, the elected cluster-head (CH) vehicle functions as the coordinator (like WLAN´s basestation) to collect/deliver the real-time safety messages within its own cluster and forward the consolidated safety messages to the neighboring CHs. Also, the CH vehicle controls channel-assignments for cluster-member vehicles transmitting/receiving the non-real-time traffics, which makes the wireless channels more efficiently utilized for the non-real-time data transmissions. Our scheme uses the contention-free MAC (TDMA/broadcast) within a cluster and the IEEE 802.11 MAC among CH vehicles such that the real-time delivery of safety messages can be guaranteed. The simulation results show that our proposed scheme can significantly improve the throughputs of vehicle data communications while guaranteeing the real-time delivery of safety messages