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Updated December 17, 2019
Smart Cars and Trucks: Spectrum Use for Vehicle Safety
Background
consider spectrum needs for transportation, including the
Increasing the autonomy of cars and trucks is seen as an
DSRC wireless standard. The goal of the initiative was to
effective way to reduce the 94% of vehicle-related
leverage technologies to improve traffic flow and safety.
accidents that are caused by human error. While some
From FY2003 through FY2014, DOT provided about $570
semiautonomous safety technologies, such as automatic
million for research, development, and testing of DSRC
braking and adaptive cruise control, are in use today,
technologies. In 2015, it awarded $43 million to three pilot
autonomous safety technologies under development would
sites (with an additional $9 million in local matches):
require cars and trucks to communicate with each other
(vehicle-to-vehicle, or V2V) and with their surroundings
Safety in a large metropolitan area. The New York
(vehicle-to-infrastructure, or V2I). V2V communication is
City Department of Transportation is outfitting 8,000
expected to reduce the number of accidents by improving
taxis, buses, and sanitation vehicles with DSRC safety
detection of oncoming vehicles and providing driver
devices to demonstrate connected-vehicle capabilities
warnings. V2I communication is expected to help highway
focused on alerting drivers to potential crashes and
operators monitor and manage traffic and provide drivers
reducing accidents with pedestrians.
with information such as weather and traffic conditions.
Interstate routes and commercial vehicles. During
These technologies are part of a congressional mandate to
invest in and advance a broader set of intelligent
severe winter weather along I-80 in Wyoming, DSRC
transportation systems to improve traffic flow and safety.
technologies are used to notify cars and trucks of
disabled vehicles. Vehicles rebroadcast the warning.
For vehicles to communicate wirelessly, they need access to
The goal is to prevent weather-related crashes.
radio frequencies. In the United States, the Federal
Communications Commission (FCC) manages commercial
Mid-sized urban area. Cars, buses, and pedestrians
are part of a DSRC pilot in downtown Tampa, FL, that
use of the radio frequency spectrum, and allocates spectrum
for specific uses. In 1999, the FCC allocated 75 megahertz
alerts drivers to reduce speeds when approaching heavy
(MHz) in the 5.9 gigahertz (GHz) band to Dedicated Short-
traffic, when forward collisions may be imminent, and
Range Communications (DSRC) uses. DSRC technologies,
where intersections are unsafe.
installed in cars and trucks and on roadways, enable V2V
In addition to these pilot projects, several manufacturers in
and V2I communications.
the United States and Europe have begun integrating DSRC
technologies into cars and trucks; truck platooning (the
Integrating DSRC technologies in vehicles and on
roadways is in its early stages. Meanwhile, the proliferation
linking of multiple trucks into a convoy through V2V
of cell phones and other devices has increased demand for
communications) has been demonstrated on U.S. highways;
and additional DSRC deployments are underway in more
spectrum, and a competing technology, Cellular Vehicle-to-
than two dozen states (see Figure 1.)
Everything (C-V2X), has emerged as an alternative to
DSRC for vehicular communications.
Figure 1. DSRC Deployments
In December 2019, the FCC proposed rules that would
reallocate the lower 45 MHz of the 5.9 GHz band for
unlicensed use (e.g., Wi-Fi), and allocate the remaining 30
MHz for transportation and vehicle-related use. Of the 30
MHz, the FCC proposed to grant C-V2X exclusive use of
20 MHz of the segment. It is seeking comment on whether
the remaining 10 MHz should remain dedicated to DSRC or
be dedicated to C-V2X. The FCC commissioners noted that
DSRC has evolved slowly and has not been widely
deployed, and the rules are intended to ensure the spectrum
supports its highest and best use. This decision has
competitive implications for the automotive, electronics,
and telecommunications industries, and may affect the
availability of safety technologies and the path toward
vehicle automation.
DSRC
Source: CRS, based on data from Volpe National Transportation
In 1998, the Transportation Equity Act for the 21st Century
Systems Center (DOT), May 2019.
(TEA-21; P.L. 105-178) directed the FCC, in consultation
with the U.S. Department of Transportation (DOT), to
https://crsreports.congress.gov
Smart Cars and Trucks: Spectrum Use for Vehicle Safety
Notes: DOT has 52 operational projects and 35 more planned,
Policy Considerations
including more than 26,000 devices deployed on vehicles in urban,
The reallocation of spectrum may encourage investment in
rural, and suburban settings.
certain technologies and priorities and disinvestment in
others. Congress may wish to consider whether reallocating
Proposed DOT Standard
the 5.9 GHz band would advance national priorities and
At the end of the Obama Administration in January 2017,
best serve the public interest.
the National Highway Traffic Safety Administration
In the debate leading up to the decision, DSRC advocates,
(NHTSA) proposed a new federal safety standard that
such as the Safety Spectrum Coalition, which includes the
would require all new light vehicles—passenger cars, sport-
Association of Global Automakers and the American
utility vehicles, and pickup trucks—to be equipped with
Trucking Associations as well as many state departments of
DSRC technology by 2023. Proponents say that this
transportation, contended that DSRC should continue to be
mandate is necessary to ensure compatibility and
supported, noting that millions of dollars have been
connectivity across all vehicles and systems. DOT projected
invested. The coalition maintains that the technology has
that implementing it could prevent more than 1,000
been thoroughly tested and deployed, is improving highway
fatalities annually. The Trump Administration has taken no
safety, and may be able to co-exist with C-V2X.
further action on this proposal, stating that DOT should
remain technology-neutral. Instead, the Administration
The Coalition for Safety Sooner—comprising 15 state
states that the 5.9 GHz band should remain dedicated to
DOTs and other state highway authorities—argued that it is
vehicle safety, but should be open to multiple technologies.
not in the public interest to delay the deployment of
New Technologies
currently available safety technologies (e.g., DSRC) while
waiting for other technologies (e.g., C-V2X, 5G) to emerge.
As governments and industry were deploying DSRC, new
wireless technologies emerged with their own spectrum
Automakers took different positions based on their differing
needs. These include Wi-Fi and C-V2X.
technology plans. Cadillac has already included DSRC in
Wi-Fi
some models, so any loss of DSRC spectrum may affect its
connected car plans, investments, and services. Volkswagen
In 2012, Congress directed the FCC to determine whether
and Toyota had paused DSRC deployment due to the lack
the 5.9 GHz band could be shared to support unlicensed
of a federal standard and spectrum uncertainties, and also
devices such as cordless phones, wireless speakers, and Wi-
because they saw benefits in C-V2X; the reallocation of
Fi devices (P.L. 112-96, Title VI, Section 6406). In
spectrum for C-V2X may drive these companies to invest in
response to a July 2016 FCC Public Notice seeking
C-V2X. Ford had already announced it would deploy C-
comments, some commenters proposed that all users share
V2X in its new vehicles in 2022; thus the reallocation of
the entire 75 MHz band, while others proposed that DSRC
spectrum for C-V2X would likely benefit Ford.
safety-of-life applications have a separate segment. The
FCC is conducting testing to determine whether Wi-Fi uses
While the debate was framed as a choice between DSRC
could cause interference with DSRC technologies. In a
and C-V2X, DSRC advocates, 5GAA, transportation
December 2019 report, DOT stated that “channel test
agencies, and safety advocates agreed that the 5.9 GHz
results showed the potential for cross-channel interference,
band should remain dedicated to vehicle safety uses and
having an impact on DSRC performance,” which likely
should not be made available for other purposes. In
informed the FCC decision to assign spectrum to each user.
contrast, the Wi-Fi Alliance, whose members include major
C-V2X
electronics companies such as Apple and Cisco, along with
consumer groups and wireless internet service providers,
Working through the 3rd Generation Partnership Project, a
argued for the spectrum to be shared between transportation
standards organization for global wireless networking,
and Wi-Fi users. These groups argued that sharing the band
some automakers and telecommunications and technology
with unlicensed uses (e.g., Wi-Fi) would expand public
companies created the C-V2X standard in 2017. Like
access to broadband and better serve the public interest.
DSRC, C-V2X can operate independently from the cellular
network for V2V and V2I communications. C-V2X can
Telecommunications providers and technology firms stand
also connect to cellular networks and is expected to be able
to benefit from more spectrum for C-V2X and Wi-Fi. C-
to use future 5G networks. 5G, when fully deployed, is
V2X relies in part on cellular networks and has the potential
expected to provide high-speed, low-latency (i.e., reduced
to increase their customer base and revenues. Wi-Fi enables
lag time) services needed for autonomous vehicles,
interconnection of devices to telecommunication networks,
allowing information between vehicles and infrastructure to
and is needed to support new 5G networks and services.
be shared almost instantaneously.
The challenge for policymakers is balancing the interests of
The 5G Automotive Association (5GAA), a consortium of
multiple stakeholders: investors in DSRC who committed
automakers, technology companies, telecommunication
funding to develop car and truck safety technologies and
providers, standards bodies, and others, supports C-V2X.
other intelligent transportation systems; consumer safety
The 5GAA asserts that C-V2X performs better than DSRC
advocates who want currently available technologies to be
in testing and is emerging as the global standard. In 2018,
diffused quickly; potential users of Wi-Fi services,
5GAA petitioned the FCC for spectrum in the 5.9 GHz
including consumers and telecommunications firms seeking
band to develop and deploy C-V2X. Testing of C-V2X has
to deploy 5G networks; C-V2X advocates eager to deploy
so far been limited to select highways in a few cities.
the next generation of vehicle safety technologies; and the
nation at large, which could benefit from the deployment of
new technologies that would improve vehicle safety, make
https://crsreports.congress.gov
Smart Cars and Trucks: Spectrum Use for Vehicle Safety
roadways more efficient, and yield economic gains that
Jill C. Gallagher, Analyst in Telecommunications Policy
often accompany the development of new technologies.
IF11260
Bill Canis, Specialist in Industrial Organization and
Business
Disclaimer
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