An adaptive channel coordination mechanism for vehicular ad hoc networks

The different types of applications in VANETs impose diversified traffic loads. Although multi-channel operations are applied in the MAC layer to improve throughput and potentially reduce the latency, the existing multi-channel approaches show some limitations to meet the changing demands of applications. In this paper, we present an adaptive channel coordination mechanism named Merak to enhance IEEE 1609.4 by adjusting the length ratio of CCH interval and SCH interval dynamically. To be specific, we model the channel interval allocation with a Markov decision process, and estimate the optimal channel interval for the current traffic load by employing a fuzzy actor-critic algorithm. The extensive experiments are conducted to observe Merak, the alternating access scheme in IEEE 1609.4 and the variable channel interval scheme (VCI). The experimental results indicate that Merak can adapt to the varying traffic loads better than the original IEEE 1609.4 and VCI, especially boosting the timeliness and delivery rate of burst emergent or periodic control message loads on the CCH and maintaining the satisfactory throughput and delivery rate of fluctuating service data on the SCHs.