Average Downstream Performance of Measured IEEE 802.11p Infrastructure-to-Vehicle Links

For the launch of intelligent transport systems (ITS), it is necessary to have detailed understanding of their performance. The draft standard IEEE 802.11p is the physical and medium access control layer (PHY/MAC) standard extension for wireless access in vehicular communications to IEEE 802.11. In order to evaluate its performance, we carried out an infrastructure-to-vehicle trial on a highway using an IEEE 802.11p prototype. This paper presents evaluation results of the average downstream performance of the PHY. Shadowing effects mainly caused by trucks lead to a strongly fluctuating performance of the link quality, especially for settings with long packet lengths and high vehicle speeds. The maximum achievable range, where the frame-success-ratio is continuously larger than 0.25, is about 700m. The maximum data volume that can be transmitted when a vehicle drives by a roadside unit is achieved at low data rates of 6 and 9Mbit/s.