There already is underutilized spectrum for V2V, Dedicated Short-Range Communication (DSRC), in the 5.9 GHz band -- the lower 45 MHz(5.850-5.895 GHz) for unlicensed uses, such as Wi-Fi, and the upper 30 MHz (5.895-5.925 GHz) for Intelligent Transportation Systems (ITS) applications, including vehicle-to-vehicle (V2V) communications.
In November 2024, the FCC finalized rules of the 5.850-5.925 GHz band, including for Cellular Vehicle-to-Everything (C-V2X) technology, which is considered a successor to DSRC for V2V and vehicle-to-infrastructure (V2I) communications.
V2V had spectrum allocated to it since 1999. But V2V+V2I got sucked into C-V2X which is astounding to me; on the one hand it make sense (5G is good at this sort of thing), but now you have gatekeepers taking their cut to provide the Service. It it were straight V2V, then it would have been free-to-use. It is astounding to me that in 2024, we still do not have the vehicle in front of you sending to your car's computers data that the driver ahead just hit his/her brakes, and you should be prepared to do the same. AEB is fine, but the current attitude seems to be "Battleship My Car" - meaning, collect all the data, make all the decisions in MY car, other cars be damned...or, ignored.
My guess is V2V just presented too many security holes to win widespread adoption. If you could go around spoofing braking events on the highway, that would be super dangerous. But that's just my guess.
As to talking with cars around you, get a ham radio license, and set your HT to 146.52 MHz -- the national simplex calling frequency. The more people we have monitoring 146.52, the better. That frequency, more than any other ham radio frequency, is the nationwide "SOS!" channel. If you have an emergency out of cellphone range, but you have an HT, often 'somebody' will hear you on 146.52 and can call for help. The other common calling frequency is 446.000 but 2 meters tends to have better range through forest terrain; and probably more people listen to "52" than 446.000 --- but try both in an emergency.
In November 2024, the FCC finalized rules of the 5.850-5.925 GHz band, including for Cellular Vehicle-to-Everything (C-V2X) technology, which is considered a successor to DSRC for V2V and vehicle-to-infrastructure (V2I) communications.
V2V had spectrum allocated to it since 1999. But V2V+V2I got sucked into C-V2X which is astounding to me; on the one hand it make sense (5G is good at this sort of thing), but now you have gatekeepers taking their cut to provide the Service. It it were straight V2V, then it would have been free-to-use. It is astounding to me that in 2024, we still do not have the vehicle in front of you sending to your car's computers data that the driver ahead just hit his/her brakes, and you should be prepared to do the same. AEB is fine, but the current attitude seems to be "Battleship My Car" - meaning, collect all the data, make all the decisions in MY car, other cars be damned...or, ignored.
My guess is V2V just presented too many security holes to win widespread adoption. If you could go around spoofing braking events on the highway, that would be super dangerous. But that's just my guess.
As to talking with cars around you, get a ham radio license, and set your HT to 146.52 MHz -- the national simplex calling frequency. The more people we have monitoring 146.52, the better. That frequency, more than any other ham radio frequency, is the nationwide "SOS!" channel. If you have an emergency out of cellphone range, but you have an HT, often 'somebody' will hear you on 146.52 and can call for help. The other common calling frequency is 446.000 but 2 meters tends to have better range through forest terrain; and probably more people listen to "52" than 446.000 --- but try both in an emergency.