  Recently, the millimeter wave (mmWave) band has been investigated as a means
to support the foreseen extreme data rate demands of emerging automotive
applications, which go beyond the capabilities of existing technologies for
vehicular communications. However, this potential is hindered by the severe
isotropic path loss and the harsh propagation of high-frequency channels.
Moreover, mmWave signals are typically directional, to benefit from beamforming
gain, and require frequent realignment of the beams to maintain connectivity.
These limitations are particularly challenging when considering
vehicle-to-vehicle (V2V) transmissions, because of the highly mobile nature of
the vehicular scenarios, and pose new challenges for proper vehicular
communication design. In this paper, we conduct simulations to compare the
performance of IEEE 802.11p and the mmWave technology to support V2V
networking, aiming at providing insights on how both technologies can
complement each other to meet the requirements of future automotive services.
The results show that mmWave-based strategies support ultra-high transmission
speeds, and IEEE 802.11p systems have the ability to guarantee reliable and
robust communications.
