FCC’s C-V2X Approval: A Dream Deferred

It wasn’t supposed to be this way.  When automotive engineers set out to save lives, the skies should open, the heavens should sing, and lives should be saved.

More than 20 years ago (25 really) automotive engineers, intelligent transportation system mavens, and the Federal Communications Commission carved out 75MHz of spectrum in the 5.9GHz band for safety-centric automotive signaling and communications.

The dream that immediately seized the industry was that by enabling these low latency communications between vehicles cars would obtain comprehensive situational awareness and would be able to drive cooperatively and avoid collisions.  At the time, about 40,000 people were dying annually in car crashes.

Last week, the FCC finalized its decision to re-allocate 45MHz of that originally designated spectrum for unlicensed uses and affirmed its decision to preserve the remaining 30MHz for safety-of-life use cases.  In the process, the dream of cooperative driving and collision avoidance has been deferred perhaps indefinitely or until additional spectrum can be found. 

Today, 40,000 people are still dying annually in the U.S. in car crashes.

The contentiousness of the decision-making process even now was evident from the FCC’s statement, which detailed the entire history of its deliberations regarding:

C-V2X standards

Band usage – i.e. applications

Channel bandwidth – 10MHz? 20MHz? 30MHz?

Communications zones

Power and antenna height limits for roadside units

Power limits for on-board units

Out of band emissions limits for RSUs and OBUs

Technology transition – from DSRC to C-V2X - two years

Other spectrum for ITS

Given the vested interests of the automotive and ITS industries, opposition to the original FCC action to calve off 45MHz of the original 75MHz of spectrum was fierce, as detailed in the final order:

“ITS America v. FCC.  After releasing the First Report and Order, the (ITS America) and the American Association of State Highway and Transportation Officials (AASHTO) petitioned the U.S. Court of Appeals for the D.C. Circuit to vacate…  The Amateur Radio Emergency Data Network (AREDN) filed a separate petition asking the court to vacate the entire First Report and Order.”

Both petitions were rejected and the FCC was affirmed by the Court.

“The Alliance for Automotive Innovation and the 5G Automotive Association filed petitions for reconsideration.”  These, too, were rejected.

The net impact of these legal actions and petitions were additional years of delay which have further clouded the prospects of C-V2X technology.  What remains for so-called “Day 1” use cases will largely revolve around infrastructure-to-vehicle communications such as red light violation warnings, emergency vehicle traffic light pre-emption, transit signal priority, and, finally, tolling

Out the window for now, along with the re-assigned 45MHz of spectrum, are applications that rely on collective perception messages and maneuver coordination messages for managing intersections and merges; and personal safety messages for mobile devices.

In many respects, C-V2X (and DSRC) technology was superseded over time by the onset of camera-based and radar-enhanced advanced driver assist systems.  Vehicle-to-vehicle communications were originally perceived as not only enabling collision avoidance but also allowing drivers to “see-through” large vehicles in their path.

The world of C-V2X received a significant lift just a month ago in Europe at the latest meeting of the 5GAA when Volkswagen and BMW demonstrated their support of C-V2X technology, marking Volkswagen’s final acknowledgement of DSRC’s limitations and anticipated demise.  The FCC decision stirred some enthusiasm, too – though muted by the recognition of the limited application set and the enormous amount of time lost to legal and regulatory disputes.

The best news lies on the distant horizon with the potential for connectionless groupcast or unicast residing in 3GPP 5G Release 16+ (i.e. sidelink).  Since the current incarnation of C-V2X is LTE-V2X (Rel. 14/15), the market will have to wait. 

Senior Technical Director of Standards at Qualcomm, Jim Misener, tells us: “We can do an IP session with LTE-V2X.  (An IP session allows a session so there is some communication, albeit (user datagram protocol), not the greatest in terms of reliable communications.)  We really need Release 16 and new spectrum in order to do anything other than ad hoc broadcasting.”

Long story short, C-V2X is simply another chapter in the folly of man.  We set out with our best of intentions and our allocated spectrum and our tests and our standards and our regulations and we fall short.  Man plans.  God laughs.  The FCC rules.