https://www.cnet.com/roadshow/news/qualcomm-c-v2x-connected-car-tech-testing-las-vegas/

While C-V2X can cover all sorts of situations, Qualcomm only mentioned "signal phase and timing and traffic messaging to vehicles." The former part of that, signal phase and timing, has already been demonstrated in Las Vegas; Audi's Traffic Light Information system has been running in Las Vegas since 2016. It beams traffic light data to the car, telling the driver when a light is expected to change.

The cellular part of C-V2X refers to the fact that it primarily operates on cellular networks, and it'll eventually be compatible with 5G once that takes over everything we know and love. But in the event cellular networks are hard to come by (not a problem in Vegas, at least on the Strip), it can also function on the 5.9-gigahertz spectrum, aka 802.11p, aka dedicated short-range communications (DSRC).