  Vehicle-to-vehicle (V2V) communications have opened the way towards
cooperative automated driving as a means to guarantee improved road safety and
traffic efficiency. The use of the millimeter wave (mmWave) spectrum for V2V,
in particular, holds great promise since the large bandwidth available offers
the possibility of realizing high-data-rate connections. However, this
potential is hindered by the significant path and penetration loss experienced
at these frequencies. It then becomes fundamental to practically evaluate the
feasibility of installing mmWave-based technologies in the vehicular scenario,
in view of the strict latency and throughput requirements of future automotive
applications. To do so, in this paper we present MilliCar, the first ns-3
module for V2V mmWave networks, which features a detailed implementation of the
sidelink Physical (PHY) and Medium Access Control (MAC) layers based on the
latest NR V2X specifications, the 3GPP standard for next-generation vehicular
systems. Our module is open-source and enables researchers to compare possible
design options and their relative performance through an end-to-end full-stack
approach, thereby stimulating further research on this topic.
