Performance comparisons of contention schemes for inter-vehicle communications

In this paper, an autonomous cruising traffic flow simulator including medium access control (MAC) for inter-vehicle communications (IVC) is constructed and the contention schemes are compared by using this simulator. The pure-ALOHA, slotted-ALOHA, and non-persistent CSMA schemes are simulated. The results of simulation show that the non-persistent CSMA is superior to the ALOHA schemes. This superiority becomes stronger with increasing communicating vehicle density. Also, it is shown quantitatively that setting the range of carrier sensing to twice the communication range can reduce the ratio of hidden stations that have a bad influence on the performance of the non-persistent CSMA scheme. In addition, the capture ratio in the IVC is considered in the simulations, and the influence of the capture effect on the performance of each scheme is discussed.