Connected Vehicle Technology Is Moving Forward … But On What Path?

The recent Intelligent Transportation Society of America (ITS America) Annual Meeting was abuzz about the Dedicated Short-Range Radio (DSRC) systems that are being deployed to improve vehicle safety. These DSRC systems enable vehicle-to-vehicle (V2V) information sharing of parameters such as speed, heading, and brake status that can be used by vehicles to avoid accidents. DSRC systems also enable vehicles to exchange information with traffic signals and road condition warning systems through vehicle-to-infrastructure (V2I) communications. The information transmitted over DSRC systems enables Connected Vehicle technology that can reduce crashes and save lives.

DSRC systems transmit on spectrum at 5.850-5.925 GHz (the “5.9 GHz band”), which is allocated by the Federal Communications Commission (FCC or Commission) primarily for DSRC pursuant to standards developed by industry through the ASTM and IEEE. DSRC standards development work, along with system design, development and testing by industry and the government, took several years to complete. Now, government agencies around the country have started deploying DSRC V2I road-side transmitters. Automakers are deploying as well. GM has already deployed DSRC in its Cadillac CTS, and both GM and Toyota have announced significant plans to deploy DSRC systems in vehicles over the next few years.

On a separate path, some wireless and automotive industry players have started developing standards through 3GPP for a new technology called Cellular-V2X (C-V2X) that would use transmissions in the 5.9 GHz band, as well through cellular systems to provide 5G data services to vehicles. C-V2X systems are being designed to provide greater data bandwidth and better transmission range than DSRC systems, although the safety benefit of these improvements was the subject of much discussion at the ITS America meeting. In mid-June 2018, 3GPP approved new standards that expand the capabilities of C-V2X. In additional, Qualcomm has announced availability of chipsets that incorporate C-V2X.

DSRC and C-V2X, once deployed, each have the potential to make vehicles more connected, thereby improving vehicle safety and enabling new and exciting visions for autonomous vehicles. However, the development of these different and potentially competing technologies also raises questions about how the future of Connected Vehicles will progress. We know that C-V2X is being developed without any attempt to provide backwards compatible services to DSRC radios that are being installed and deployed today. Will that mean that infrastructure providers will have to deploy two systems of road-side transmitters to communicate with Connected Vehicles that may have only one DSRC or one C-V2X radio? Similarly, will automakers have to include both a DSRC and a C-V2X radio in vehicles so that can communicate with whatever roadside infrastructure is deployed in an area? And will vehicles equipped with only a C-V2X radio not be able to take advantage of the safety information that will be transmitted by a vehicle equipped with a DSRC radio?

Many industry players have questions as well about whether (or how) the 5.9 GHz band, which is divided into seven channels, can be shared by DSRC and C-V2X transmitters that are incompatible with each other. Some parties have called for limiting the number of channels that could be used by DSRC, so that separate channels are available for C-V2X use. However, would such a scheme leave enough spectrum for DSRC V2V and V2I transmissions that are now being deployed? And even if it did, how disruptive would such a rechannelization be to existing and planned DSRC deployments, which were developed to operate using the current band plan?

Currently, the FCC rules only permit DSRC transmissions in the 5.9 GHz band, but it is expected that supporters of C-V2X technology will ask the Commission to permit it to also operate in the band. The FCC already has an open proceeding to consider whether it should reclaim some of the 5.9 GHz band for other uses and whether it should permit the use of some or all of the 5.9 GHz band for unlicensed wireless devices in general. Would unlicensed devices be capable of protecting DSRC and, potentially, C-V2X transmissions? The FCC has conducted some preliminary testing on this and is expected to release the results of that testing soon.

While there are a number of questions that have yet to be answered, it is clear that government agencies and automakers are proceeding to deploy DSRC with the hope and expectation that these questions can be answered such that the safety benefits expected from Connected Vehicles can be brought to the American public over the next few years and expanded in the future. Cooperation between the government and industry has been a hallmark of the Connected Vehicle effort to date, and continued cooperation will be needed given the high stakes involved.