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Time-Slot Reservation and Channel Switching Using Markovian Model for Multichannel TDMA MAC in VANETs

Efficient communication in the intelligent transport system requires the vehicles to transmit safety and non-safety messages timely without any loss. In multi-channel MAC, the attributes of SCH channels are frequency range, frequency limit, power limit, distance covered, and channel performance. Based on these channel properties, messages must be transmitted using the most appropriate channel. Existing multi-channel MAC approaches randomly choose the available SCH channel to transmit the messages. Random selection of the channel leads to over-utilization or under-utilization of channel resources. The channel allocation in the proposed approach reserves the most appropriate SCH and optimizes resource utilization. The proposed variable size TDMA approach for SCH channel allocation considers a large number of contending vehicles with the collision-free allocation of resources. The paper also focuses on reducing the transmission collision and re-usability of the time slot for message transmission. Markovian modeling determines the probability of successfully reserving the time slot and switching to the required SCH. Simulation results prove that the probability of time slot reservation in the required SCH is approximately 0.6 for the proposed approach and approximately 0.2 for other approaches.