Sub-6GHz Assisted MAC for Millimeter Wave Vehicular Communications
Future connected and automated driving applications can require larger bandwidth and higher data rates than currently supported by sub-6GHz V2X technologies (e.g., DSRC, ITS-G5 or C-V2X). This has triggered interest in developing mmWave vehicular communications. However, solutions are necessary to solve the challenges resulting from the use of high-frequency bands and the high mobility of vehicles. This article contributes to this active research area by proposing a sub- 6GHz assisted mmWave MAC that decouples the mmWave data and control planes. The proposal offloads mmWave MAC control functions to a sub-6GHz V2X technology. This approach improves the operation of the MAC as the control functions benefit from the longer range, and the broadcast and omnidirectional transmissions of sub-6GHz V2X technologies. This study demonstrates that the proposed sub-6GHz assisted mmWave MAC reduces the control overhead and delay, and increases the spatial sharing compared to mmWave communications using a configuration of IEEE 802.11ad tailored to vehicular networks. The proposed MAC is here evaluated for V2V communications using 802.11p for the control plane and 802.11ad for the data plane, although it can be adapted to other technologies such as C-V2X and 5G NR-V2X.