Mathematical Analysis of EDCA's Performance on the Control Channel of an IEEE 802.11p WAVE Vehicular Network

Wireless networks for vehicular environments are gaining increasing importance due to their ability to provide a means for stations on the roadside and radio units on board of vehicles to communicate and share safety-related information, thus reducing the probability of accidents and increasing the efficiency of the transportation system. With this goal in mind, the IEEE is currently developing the Wireless Access in Vehicular Environments (WAVE) IEEE 802.11p standard. WAVE devices use the IEEE 802.11's Enhanced Distributed Channel Access (EDCA) MAC protocol to compete for the transmission medium. This work proposes an analytical tool to evaluate the performance of EDCA under the specific conditions of the so-called control channel (CCH) of a WAVE environment, including the particular EDCA parameter values and the fact that all safety-critical data frames are broadcasted. The protocol is modeled using Markov chains and results related to throughput, frame-error rate, buffer occupancy and delay are obtained under different traffic-load conditions. The main analysis is performed assuming that the CCH works continuously, and then an explanation is given as to the considerations that are needed to account for the fact that activity on the CCH is intermittent.