Application-Level Performance of IEEE 802.11p in Safety-Related V2X Field Trials

In this article, we study the application-level performance of safety-related communications over IEEE 802.11p, presenting the first outcomes resulting from several short- and medium-range field tests. These have been performed with low-cost off-the-shelf equipment operating on the IEEE 801.11p PHY/MAC stack, with devices configured or modified, when necessary, with open-source software to ensure repeatability. In particular, this article discusses the relation that transmission power, antenna quality, distance, and different degrees of congestion, alone and combined, have on round-trip times, TCP Goodput, UDP Goodput, Jitter, and Datagrams or Packets lost. It also details an investigation on the hidden terminal problem, by presenting the results of field tests where destructive interference due to hidden terminals has been artificially introduced at the host premises. Finally, this article presents the metrics obtained by performing initial mobility tests in urban and suburban scenarios. The results are encouraging and attest that, with the appropriate transmission power, it is possible to provide satisfying safety guarantees under the tested conditions.