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

Abstract

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, SCH channels have different properties in terms of the frequency range, frequency limit, power limit, distance covered, and channel parameters. 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 overuse of the channel resources or lack of the resources due to inappropriate channel selection. The proposed approach provides a way to reserve the most appropriate SCH leading to optimized resource utilization. For collision-free allocation of resources to a large number of contending vehicles, we have proposed a variable size TDMA approach for SCH channel allocation. The paper also focuses on reducing the transmission collision and re-usability of the time slot for timely 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.