The FCC is facing a new lawsuit over its move last year to rework the spectrum and technology dedicated to connected cars. The action helps crystalize the ongoing debate over how exactly automobiles should communicate with each other and with roadside infrastructure like stoplights and crosswalks.

It's also an important issue for companies in the 5G industry considering many – including stalwarts like Qualcomm – are hoping to provide some of the technology that would power future connected cars.

The latest development on this topic comes from the Intelligent Transportation Society of America (ITS America) and the American Association of State Highway and Transportation Officials (AASHTO), two transportation advocacy groups. As reported by Reuters, they filed a legal challenge in the US Court of Appeals for the District of Columbia in an attempt to reverse the FCC's recent changes to the 5.9GHz spectrum band for connected cars.

A boon to unlicensed spectrum users

Late last year, in the waning days of the Trump administration, the FCC voted to take away around 60% of the spectrum for the connected car industry and instead use it for unlicensed operations. The move received cheers from the Wi-Fi industry, but a number of transportation officials, lawmakers, carmakers and others said the action would make it more difficult for connected car applications to work.

"The FCC's vote was a gift to corporate interests that jeopardizes ongoing efforts to modernize our transportation systems with emerging technologies that reduce congestion, cut carbon pollution and make our streets safer for everyone," argued Rep. Peter DeFazio (D-Oregon) and chair of the House Committee on Transportation and Infrastructure, in an opinion article in The Hill published this week.

Others agree. "The current allocation of 30MHz [of spectrum for connected cars] is insufficient," the Maryland Department of Transportation (MDOT) told the FCC in a recent filing. "Maryland is actively deploying connected vehicle technologies to support a variety of safety and mobility applications across our transportation infrastructure. From in-vehicle pedestrian detection to smarter signals, we are implementing technology today that depends on the reasonable allocation of spectrum for optimal performance. Given the reduced spectrum allocation, several of those applications, some of which are already under way, such as signal phasing for safety and eco-driving, will no longer be viable."

But some argue that unlicensed spectrum remains critical for a variety of applications. "This last year demonstrated that home connections must support multiple devices engaged in high-bandwidth, low-latency applications simultaneously. In a world where every member of a household may need to work or learn from home at the same time, the need for increased Wi-Fi capacity is obvious and irrefutable," public interest group Public Knowledge told the FCC.

From 802.11 to cellular

Importantly, the FCC last year also voted to implement a change to the technology underpinning connected car communications. Instead of previous efforts to use the Dedicated Short-Range Communications (DSRC) standard, which is based on the 802.11 Wi-Fi protocol, as the technology of choice for connected cars, the FCC decided instead to approve the Cellular Vehicle-to-Everything (C-V2X) standard. The 5G industry cheered that move because V2X stems from the industry's 4G specifications and likely will support 5G applications in the future.

"The wireless industry, automotive industry, state departments of transportation and local agencies are eager to deploy C-V2X technology and equipment in vehicles and on roadways," Qualcomm told the FCC. Indeed, the company this week announced a new C-V2X demonstration for smart cities in Peachtree Corners, Georgia.

But some state transportation departments are raising concerns about the shift from DSRC to C-V2X. For example, Utah Department of Transportation (UDOT) said that it has already invested $2.3 million in the deployment of DSRC systems in the 5.9GHz band. "These are not pilot deployments or tests, but are in a fully operational, permanent environment," the agency wrote to the FCC.

As a result, UDOT told the FCC that users of DSRC should be compensated for the cost of replacing those systems with C-V2X.

How the debate will play out remains unclear. The FCC remains split between two Democratic and Republican commissioners.

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— Mike Dano, Editorial Director, 5G & Mobile Strategies, Light Reading | @mikeddano