  The Long Term Evolution (LTE) standard enables, besides cellular
connectivity, basic automotive services to promote road safety through
vehicle-to-infrastructure (V2I) communications. Nevertheless, stakeholders and
research institutions, driven by the ambitious technological advances expected
from fully autonomous and intelligent transportation systems, have recently
investigated new radio technologies as a means to support vehicular
applications. In particular, the millimeter wave (mmWave) spectrum holds great
promise because of the large available bandwidth that may provide the required
link capacity. Communications at high frequencies, however, suffer from severe
propagation and absorption loss, which may cause communication disconnections
especially considering high mobility scenarios. It is therefore important to
validate, through simulations, the actual feasibility of establishing V2I
communications in the above-6 GHz bands. Following this rationale, in this
paper we provide the first comparative end-to-end evaluation of the performance
of the LTE and mmWave technologies in a vehicular scenario. The simulation
framework includes detailed measurement-based channel models as well as the
full details of MAC, RLC and transport protocols. Our results show that,
although LTE still represents a promising access solution to guarantee robust
and fair connections, mmWaves satisfy the foreseen extreme throughput demands
of most emerging automotive applications.
