An optimal back-off parameters study for multi-channel MAC protocols in VANETs

Delay and reliability sensitive safety messages and throughput sensitive non-safety messages are transmitted in VANETs. Throughput and delay are always opposed in wireless networks, so it is necessary to reach the optimum point between these two parameters in many cases. This paper presents an optimization method of the back-off parameters in multi-priority supported multi-channel MAC protocol in VANETs to solve this problem. This method calculates throughput and delay of the network, then determines the optimum transmitting probabilities of the two classes of messages by an optimization model. Then the optimum back-off parameters can be calculated according to the transmitting probabilities. Simulation results show that this method can achieve the aim and remain stable.