Sub-6GHz Assisted MAC for Millimeter Wave Vehicular Communications

Sub-6GHz vehicular communications (using DSRC, ITS-G5 or C-V2X) 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 communications. However, solutions are necessary to solve the challenges resulting from the use of high-frequency bands and the high mobility of vehicles. 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 the broadcast and omnidirectional transmissions of sub-6GHz V2X technologies. This simulation study demonstrates that the proposed sub-6GHz assisted mmWave MAC reduces the control overhead and delay, and increases the spatial sharing compared to a mmWave-only configuration (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. However, the proposal is not restricted to these technologies, and can be adapted to other technologies such as C-V2X and 5G NR.Comment: 8 pages, 5 figure

On the interplay between scheduling interval and beamwidth selection for low-latency and reliable V2V mmWave communications

Abstract The interest in mmWave communications has risen sharply in the last years motivated by their widespread consideration as a technological solution capable of dealing with the stringent rate requirements currently demanded by wireless networks. This momentum gained by mmWave bands springs several technical challenges regarding the allocation of radio resources particularly complex in V2V communications, where reliability/latency constraints are extremely demanding, and links between vehicles are highly influenced by their mobility, beam misalignment and blockage between counterparts. In this context we analyze the interplay between the beamwidth assignment and the scheduling period when links between transmitters and receivers in V2V communications are established in a distributed fashion by means of Matching Theory. Extensive simulations performed for the aforementioned scheme and other alternatives from the literature reveal that, even in simplistic vehicular setups, the throughput performance and the latency/reliability trade-off is affected not only by the selected antenna beamwidths — and their suitability to the radio conditions imposed by the dynamics of the scenario under analysis — but also by a proper choice of the scheduling interval/beam realignment period. A poor choice in the latter for a given beamwidth being responsible of drop events