Random Access Congestion Control for Periodic Safety Messages in Dense Traffic Networks

The cooperative intelligent transport systems (CITS), which employ vehicular wireless communications to connect vehicles on the road as well as infrastructures, have gained attention as a promising technology that will significantly reduce traffic congestion and road accidents. The IEEE wireless access in vehicular environment (WAVE) is one of the most promising vehicular communication standards; however, when a large number of vehicles and roadside units participate in wireless communication, channel congestion problems arise due to the carrier sense multiple access with collision avoidance (CSMA/CA) characteristics of WAVE. In this paper, we present random access congestion control methods, which utilize random distribution and flexible management of the sync interval. The simulation results from a congested urban intersection scenario show that the proposed methods greatly increase the successful reception rate of safety messages compared with the WAVE CSMA/CA.