Sub-6GHz Assisted MAC for Millimeter Wave Vehicular Communications

Abstract

Sub-6GHz vehicular communications (using DSRC, ITS-G5 or LTE-V) have been developed to support active safety applications. Future connected and automated driving applications can require larger bandwidth and higher data rates than currently supported by sub-6GHz V2X technologies. This has triggered the interest in developing mmWave vehicular communication solutions that can solve the challenges resulting from the use of high-frequency bands and the high mobility of nodes. This paper 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 (beam alignment, neighbor identification and scheduling) to a sub-6GHz V2X technology, and reserves the mmWave channel for the data plane. This approach improves the operation of the MAC as the control functions benefit from the longer range and omnidirectional transmissions of sub-6GHz V2X technologies. The conducted study demonstrates that the proposed sub-6GHz assisted mmWave MAC reduces the control overhead and delay, and increases the spatial sharing compared to a standard IEEE 802.11ad. The proposed MAC is evaluated in this study for V2V communications with 802.11p in the control plane and 802.11ad in the data plane. However, the proposal is not restricted to these technologies, and can be adapted to other technologies such as LTE-V or Cellular V2X and 5G NR.