MAC Channel Congestion Control Mechanism in IEEE 802.11p/WAVE Vehicle Networks

IEEE 802.11p/WAVE (Wireless Access in Vehicular Environments) is an emerging family of standards intended to support wireless access in Vehicular Ad Hoc Networks (VANETs). Broadcasting of data and control packets is expected to be crucial in this environment. Both safety-related and non-safety applications rely on broadcasting for the exchange of data or status and advertisement messages. Most of the broadcasting packet is designed to be delivered on a given frequency during the control channel (CCH) interval set by the IEEE 1609.4 draft standard. However, the AOS (Adaptive Offset Slot) mechanism is firstly developed based on the estimation of potential neighboring vehicles through broadcasting Hello messages, and then calculating the expected offset slots for reduce the collision situations, and thus improve transmission performance.