Efficient Channel Coordination for Multi-channel MAC in VANETs

Many Medium Access Control (MAC) protocols are proposed to adapt to dynamically changing vehicle traffic condition, such as bandwidth to deliver both safety and non-safety packets. One of them is combination between TDMA and CSMA schemes in the Control CHannel (CCH). With different traffic condition, the length of TDMA-based period can be adjusted to improve throughput on the service channel for exchanging non-safety packets. One of the well-known problems of TDMA-based MAC protocols is the overhead when node density is high. In this paper, we propose a modified packet transmitted in the TDMA-based period to reduce transmission overhead. The simulation results show that the MAC protocol with modified packet supports efficient packet delivery ratio of control packet in the CCH. Key word: multichannel MAC, TDMA and CSMA schemes, transmission overhead.