The exploration is built upon Delphi's, Nissan's, Cohda Wireless' and Savari's experiences in Asia, Europe and U.S.A. It describes and derives lessons from all four companies' contributions in projects such as SMARTWAY in Japan, Drive C2X and in Europe, as well as the Connected Vehicle Safety Pilot in the U.S.A. All the above programs were implemented by means of the Dedicated Short Range Communication (DSRC) technology in the SHF spectrum based on the IEEE 802.11p/Wireless Access in Vehicular Environments (WAVE) standard. The study is supplemented with insights regarding complementary technologies such DSRC in the lower UHF frequency band (i.e. 700 MHz) as well as a V2X implementation through the 4G LTE (Long Term Evolution) cellular telecommunication technology. This paper addresses issues regarding the physical layer (PHY) of the DSRC system. The combination of the delay profile caused by multipath propagation along with the motion-based Doppler spread leads to time and frequency dispersion. This limits the number of bytes acceptable for reliable communication or requires a solution at the receiver end. The analysis of the Doppler spread shows that DSRC implemented at 700 MHz is more immune from data packet length issues as opposed to 5 GHz DSRC. On the other hand, 700 MHz DSRC exhibits a much longer delay spread. Thus, guard time interval specified in ASTM E2213-03 cannot be applied as is to 700 MHz DSRC. This paper refers to the German project CoCarX and the Japanese SKY for pedestrian for studying the feasibility a V2X system built on the 4G/LTE technology and its infrastructure. It provides on a vision for an accelerated V2X deployment based on a heterogeneous system. Last, we recommend the ITS stakeholders to carry out extensive research and validation works on DSRC capacity for ensuring a large scale deployment.

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