Fair Channel Distribution Based Congestion Control in Vehicular Ad Hoc Networks
Vehicular ad hoc network (VANET) serves as one of the significant enabling technologies in intelligent transportation system (ITS) Accurate and up to date information received by vehicle to vehicle (V2V) communication prevents road accidents. The most critical matter in IEEE 802.11p based V2V communications is channel congestion, as it results in unreliable safety applications. In this paper, two types of safety messages beacon and event driven are used to reduce hazards. Beacon is disseminated periodically, providing the necessary information about their neighbor status. Event driven is sent whenever a danger has been detected. As the number of vehicle increases, the number of safety messages disseminated by vehicle also increases, which results in congestion in the communication channel. As a countermeasure, we have proposed the most prominent decentralized congestion control (DCC) algorithm based on transmit rate. The effects of congestion on vehicular safety can be controlled by designing a DCC algorithm including priority model and transmission rate of the messages, which provides more reliable and timely reception of safety messages. DCC algorithm controls the congestion by fairly distribution of channel to each vehicle. A novel approach is proposed regarding congestion control, and performance is analyzed with respect to some indexes such as packet delivery rate (PDR) end to end (E2E) delay, throughput, and transmit frequency.