It’s official: DSRC is out, C-V2X and Wi-Fi-sharing is in at 5.9 GHz

At the end of the Obama administration, Dedicated Short-Range Communications at 5.9 GHz for intelligent transportation systems was on the cusp of becoming required in all new vehicles, setting a mandate for the use of spectrum which had largely lain fallow for more than 20 years. Four years later, as the Trump administration comes to a close, the band is on a completely different trajectory, to use cellular vehicle-to-everything technology and share the airwaves with unlicensed systems.

The Federal Communications Commission voted this week to split the 75 megahertz of formerly-DSRC spectrum at 5.850-5.925 GHz, allocating the lower 45 megahertz of the band for unlicensed use and the upper 30 megahertz for intelligent transportation systems that must use C-V2X technology.

“While the Commission designated Dedicated Short-Range Communications (DSRC) services as the technology standard for ITS services over twenty years ago, DSRC has not been meaningfully deployed, and this critical mid-band spectrum has largely been unused for decades. Today’s action therefore begins the transition away from DSRC services—which are incompatible with C-V2X—to hasten the actual deployment of ITS services that will improve automotive safety,” the FCC said in a release.

The change passed with bipartisan support; all three Republican members of the commission voted in favor, and the two Democrats concurred. The FCC made its decision over objections from the U.S. Department of Transporation, which argued that the full 75 megahertz was needed for intelligent vehicle transportation systems and that reducing the spectrum allocation “jeopardizes both the existing deployment of, and innovation in,
V2X technology.”

The FCC’s new rules enable full-power indoor unlicensed operations in the unlicensed portion of the band to begin immediately, as well as
“opportunities for outdoor unlicensed use on a coordinated basis under certain circumstances.” Meanwhile, transportation users in the band have to vacate the lower 45 megahertz within a year.

The change in allocation was opposed by the automotive industry, which has long tried to hold on to the exclusive use of the 5.9 GHz band in spite of the fact that very little use was being made of the band, and that use has been mostly in test and pilot projects. Some of those projects started to use both technologies in anticipation of rule changes in the band, but others did not. The NW U.S. 33 Corridor Council of Governments in Ohio protested in an FCC filing that after more than $105 million in public/private investments, their project was “having the proverbial rug pulled out from under it, just as it is to go operational.”

However, there has been increasing development in CV2X since the DSRC mandate fell apart. While the Department of Transportation accused the FCC of having “prematurely chosen an unproven technology ‘winner’ by mandating the use of C-V2X at 5.9 GHz, Qualcomm, for its part, said in an ex parte filing that “C-V2X is ready to be deployed across America … . Ford and other automakers want to sell cars equipped with highly advanced C-V2X technology, and state and local transportation agencies are ready to install C-V2X roadside units in their jurisdictions.”

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