Analyzing the Impact of the Coexistence With IEEE 802.11ax Wi-Fi on the Performance of DSRC Using Stochastic Geometry Modeling

The proliferation of high data-rate applications and services in next-generation WLANs, as well as the significant increase in the number of Wi-Fi devices, is triggering the search for more bandwidth. For this, the Federal Communications Commission (FCC) is considering a proposal to permit devices, such as those that use the IEEE 802.11 (Wi-Fi) protocol, to operate in the 5.9 GHz band allocated to the intelligent transportation system (ITS). However, the nature of these bands poses a challenge since ITS dedicated short range communications (DSRC) networks use them to share safety-critical messages and may be subject to severe interference from other coexisting transmissions. We discuss the impact of coexistence of Wi-Fi networks on the performance of DSRC through an analytical framework based on stochastic geometry. We consider the recent IEEE 802.11ax Wi-Fi standard, and analyze uplink and downlink transmissions, with voice and background traffic being the highest and lowest priority traffic, respectively. We also validate the fixed contention window size of the derived stochastic geometry model using NS-3 simulations. The proposed framework can serve to increase awareness among regulatory bodies of the extent to which coexistence will adversely affect the performance of DSRC.