IEEE 802.11p under congestion in an Infrastructure-to-Vehicle communication approach

Possible applications of the so-called Intelligent Transportation Systems, or connected vehicles, range from critical to trivial and comprise road safety, traffic and transportation efficiency, and infotainment. The networks underlying these applications are under development and test, but few works are available in the literature that present results from real testbeds. This article is about the performance of IEEE 802.11p networks under congestion in vehicular environments, analysed from an infrastructure-centric point of view. In particular, as no assumptions are made about the communication behavior of vehicles, the paper is a starting point in answering the question of how much guarantees the standardized technologies are able to provide in worst-case scenarios of network congestion. An IEEE 802.11p first physical testbed has been developed, and it has been used to perform tests on latency, bandwidth, and packet losses with real network traffic. Although to answer the question completely tests with farther distances and different devices have to be made, these first results appear promising. The RoadSide Units ability to deliver critical messages does take a hit during signaling storms generated by vehicles, but due to the small size and connection-less nature of the packets expected to be employed, some bandwidth remains available, although some redundancy mechanism, carefully designed, might be needed to overcome relatively high packet loss ratios.