Performance analysis and enhancement of IEEE 802.11p/1609 protocol family in vehicular environments

Vehicles in Intelligent Transportation System employ IEEE 802.11p/1609 protocols to communicate with other vehicles or roadside infrastructure within a specific area. Messages related with traffic safety can be delivered timely for collision avoidance and etc. Meanwhile, non-safety related infotainment messages can also be transmitted besides safety-critical information. Many of the safety critical messages are periodic heartbeat beacon frames broadcasting the status of a vehicle. In this paper, the fairness deterioration of these heartbeat beacons is investigated through exhaustive simulations. The simulation results reveal that not only more beacon frames will be lost when the density is high, but also the fairness cannot be guaranteed any more in such circumstance. We define a “Fairness Index” to show this Fairness deterioration. The “bandwidth wastage” problem on SCH is also considered in this paper. And then, we proposed Frame-Fit algorithm to mitigate this phenomenon. The effectiveness of the proposed algorithm is also validated through simulations.