Just as some are saying the proposal to mandate a vehicle-to-vehicle (V2V) system based on Dedicated Short Range Communications in all new cars is on life support, 5G Americas has published a white paper that compares cellular V2X (C-V2X) and DSRC.
The paper points out that C-V2X has several key advantages over DSRC, including longer range and enhanced reliability; more consistent performance in congested traffic; an evolution path toward 5G for emerging applications; and better coexistence with other technologies.
In addition, it notes that based on link level simulation analysis, C-V2X can achieve line-of-sight and non-LOS V2X ranges of 443 and 107 meters, respectively, compared to 240 and 60 meters, respectively, for DSRC. Longer range can be directly translated into earlier alerts and better visibility of unexpected and potentially dangerous situations. It also means vehicles can travel at higher speeds while still being able to stop in time to avoid hazardous conditions.
But it's also clear that the debate over DSRC versus C-V2X is far from over. The National Highway Traffic Safety Administration (NHTSA) has done extensive research and testing of the IEEE 802.11p-based DSRC technology for V2V communications. Meanwhile, the cellular industry has been lobbying for C-V2X. The 3GPP Release 14 standard includes support for C-V2X use cases, and they say that leveraging existing cellular infrastructure would reduce costs and accelerate the path to improved safety on the roads.
The DSRC standard, which was finalized in 2009, is still preferred by some automakers. Representatives of Panasonic Corporation of North America, the Safety Spectrum Coalition and several state departments of transportation recently met with FCC staff to provide updates on myriad DSRC projects that are planned or underway and to advocate for protecting all seven channels of 5.9 GHz spectrum for DSRC.
The 5G Americas white paper says that over the years, the SAE DSRC Technical Committee in the U.S. and the ETSI ITS Technical Committee in Europe have developed a set of applications and specific V2X messages, and it’s important to note that these standards assume the access layer to be DSRC/ITS-5G. “It is natural to expect these standards can be adapted, if needed, to run atop cellular V2X, including both LTE and 5G access layers,” the paper states. “To this end, the SAE Cellular-V2X Technical Committee is working on a new application layer standard SAE J3161.”
A number of regions have conducted extensive trials with 802.11p and adopted the technology for initial deployment of V2X, according to 5G Americas. At the same time, a number of cities and infrastructure providers offer solutions with LPWAN combined with cellular in the car.
Moving forward, it’s expected that a broader adoption of 5G cellular will occur for V2X. Still, the paper states, the ITU and countries need to allocate 5G spectrum, operators need to deploy 5G and on-board unit manufacturers need to evolve their existing products to support 5G New Radio when available if the desire is to fully leverage 5G end-to-end capabilities.