e- quency of ITS band may be shifted to 64.80 GHz and extended to 2.16 GHz of band- width (to avoid overlapping with two IEEE 802.11ad channels and to increase ITS bandwidth). In the quest for increased network capacity, reduced cell sizes and the use of wider system bandwidths (whether contiguous or via carrier aggregation) have been actively investigated in the past decade. The use of mmWave spectrum for sidelink communications is believed to have several advantages for V2I communication, wherein transitory, high data rate Vehicle-to-Everything (V2X) Communications 801 dBm/MHz European V2X spectrum allocation 10 MHz 23 dBm/MHz 13 dBm/MHz ETSI EN 302 686 EIRP 43 dBm, Transmit power up to 27 dBm, antenna gain 14-23 dBi Frequency (GHz) ETSI ITS G5A ETSI ITS G5B EU-Wide available safety ETSI ITS G5D Nonsafety applications under ITS Future applications decentralized congestion applications control Figure 7.6 Region-specific ITS spectrum allocation in Europe [24,25]. connection can be established between vehicle and nearby base stations (small cells) to exchange delay-insensitive data (e.g., map updates and infotainment data in the downlink, and collected traffic and sensor information for large-scale traffic monitoring in the uplink); and for directional V2V communication for supporting specific use cases, such as communi- cation between adjacent vehicles in a platoon. Although nmWave communication is very attractive from the data throughput perspective, it creates challenges for the physical layer. Due to high propagation loss (path loss) and its susceptibility to shadowing, the use of mmWave bands is deemed suitable for mainly short range (a few hundred meters) and point-to-point LoS communications. Furthermore, since the Doppler spread is linear func- tion of the carrier frequency, the amount of Doppler spread in the 60 GHz band will be 10-30 X of that in 2-6 GHz band. Radio signals used for communication with the cellular network and between vehicles can also be used for position estimation. The achievable posi-