A Cluster-based TDMA System for Inter-Vehicle Communications

This paper presents a cluster-based TDMA (CBT) system for inter-vehicle communications. In intra-cluster communications, the proposed CBT uses a simple transmitand-listen scheme to fast elect a VC (VANET Coordinator) and it allows a VN (VANET node) to randomly choose a time slot for bandwidth requests (BR) without limiting the number of VNs. In inter-cluster communications, when two clusters are approaching, the CBT can quickly resolve the collisions by re-allocating time slots in one of the clusters. To analyze the performance of the proposed CBT, we derive mathematical equations using probability. The performance metrics of our interests include the average number of time slots for electing a VC, the average number of time slots required for BR, and the total number of time slots required before data can be successfully transmitted. The analytical results are finally validated by a simulation. Both the analytical and simulation results show that the proposed CBT spends less time to form a small-sized cluster than IEEE 802.11p. Additionally, when the number of joining VNs is increased, CBT takes less waiting time before a VN can effectively transmit data.