Updated April 21, 2021
Smart Cars and Trucks: Spectrum Use for Vehicle Safety
A November 2020 decision by the Federal Communications
technologies. DSRC, one type of ITS technology in the
Commission (FCC) to reconfigure the 5.9 gigahertz (GHz)
early stages of deployment, is installed in cars and trucks
spectrum band may change the evolution of U.S. vehicle
and along roadways to enable V2V and V2I
safety technologies. The decision has implications for
communications that are not reliant on cellular networks. C-
domestic spectrum use and vehicle technologies—and their
V2X, which has emerged as an alternative to DSRC, offers
application to international standards for connected vehicles
safety features similar to DSRC that are not reliant on
and infrastructure.
cellular networks, but can also connect to those networks.
The 5.9 GHz band was previously allocated for intelligent
C-V2X advocates assert that it offers better safety features
transportation systems (ITS)—specifically, for Dedicated
and greater capacity for data throughput.
Short Range Communications (DSRC) vehicle safety
In 2019, the FCC considered a reallocation of the 5.9 GHz
technologies. The FCC split the band, allocating a part to
band to expand unlicensed uses such as Wi-Fi access and
unlicensed use (e.g., Wi-Fi) and reducing the portion
accommodate the growing number of consumer and
available to ITS vehicle safety technology by more than
commercial wireless devices. It also considered whether the
half. The commission assigned that portion exclusively to
remaining portion of the band should be dedicated to both
Cellular Vehicle-to-Everything (C-V2X), which it selected
C-V2X and DSRC or only C-V2X. On November 18, 2020,
as the U.S. standard for vehicle safety technologies. It
the FCC adopted rules that would reallocate the lower 45
eliminated spectrum for DSRC use altogether.
MHz of the band to unlicensed uses and the upper 30 MHz
The U.S. Department of Transportation (DOT) opposes this
of the band to ITS, specifically for C-V2X technologies.
decision. DOT has been funding, testing, and piloting
The FCC granted unlicensed users immediate access to the
DSRC for more than 20 years, and it says the technology is
lower band and required DSRC licensees operating in the
capable of cutting traffic fatalities now. The FCC asserts
lower band to move to the upper band within one year. It
that automakers have been slow to deploy DSRC—about
also required users in the upper band to use C-V2X. To
15,000 vehicles have been equipped with it since 2017—
accommodate DSRC users, it proposed a timeline (two
and that the 5.9GHz band would be better used to support
years) for DSRC users to transition to C-V2X or cease
consumer wireless needs and new vehicle technologies.
operating. The FCC is seeking comment on the timeline.
While some policymakers have applauded the FCC’s
DSRC
decision to increase spectrum for consumer use, the
In 1998, the Transportation Equity Act for the 21st Century
chairman of the House Transportation and Infrastructure
(P.L. 105-178) directed the FCC, in consultation with DOT,
Committee has requested that the FCC reconsider its
to consider spectrum needs for ITS, specifically including
decision, saying it “will undermine roadway safety.”
DSRC technologies, to improve traffic flow and safety. The
Background
DSRC standards, including certification test procedures,
Increasing the autonomy of cars and trucks is seen as an
were issued in 2016. More than $2.2 billion in federal, state,
effective way to reduce the 94% of vehicle-related
local and private-sector investments have been made since
accidents that involve human error. While some
2003 in DSRC testing and deployment, including pilots in
semiautonomous safety technologies, such as automatic
27 states, with more than 100 additional testing sites
braking, are in use today, many autonomous technologies
planned. Among its major demonstration sites are New York
under development would require cars and trucks to
City—where 8,000 taxis, buses, and sanitation vehicles
communicate wirelessly with one another (vehicle-to-
have been outfitted with DSRC to alert drivers to potential
vehicle, or V2V) and with their surroundings (vehicle-to-
crashes and reduce accidents with pedestrians; Interstate 80
infrastructure, or V2I). V2V communication is expected to
in Wyoming—where DSRC notifies cars and trucks of
reduce the number of accidents by improving detection of
disabled vehicles during severe winter weather to prevent
oncoming vehicles and providing driver warnings. V2I
crashes; and downtown Tampa, FL—where drivers are
communication is expected to help highway operators
alerted to reduce speeds when approaching heavy traffic to
monitor and manage traffic and provide drivers with
avoid collisions and where intersections are unsafe.
information such as weather and traffic conditions.
New Technologies
For vehicles to communicate wirelessly, they need access to
As DSRC was being piloted and deployed globally, demand
radio frequencies. In the United States, the FCC manages
for wireless technologies and spectrum for them also
commercial use of the radio frequency spectrum, and
increased exponentially.
allocates spectrum for specific uses. V2V and V2I
technologies are part of a congressional mandate to advance
Wireless Technologies
ITS to improve traffic flow and safety. In response, the
In 2012, Congress directed the FCC to determine whether
FCC set aside 75 megahertz (MHz) of spectrum in the 5.9-
the 5.9 GHz band could be shared for unlicensed use, such
GHz band in 1999 specifically for DSRC vehicle safety
as mobile phones and Wi-Fi enabled devices (P.L. 112-96,
https://crsreports.congress.gov
link to page 2 
Smart Cars and Trucks: Spectrum Use for Vehicle Safety
Title VI, §6406). In response to a 2016 FCC Public Notice,
global vehicle safety market. DOT counters that DSRC has
some commenters, including wireless service providers,
been the recognized safety technology in most
proposed that users share the entire 5.9 GHz band (75
industrialized countries for more than 20 years, is tried and
MHz). DOT and some state transportation agencies, public
tested, and should not be abandoned.
safety agencies, and some automakers raised interference
U.S. Competitiveness
concerns and asserted that the entire band should remain
The third issue focuses on U.S. competitiveness in the
dedicated to ITS. FCC said its testing showed potential for
global auto technology market. There is no global
sharing; however, it decided to split the band instead
consensus on a single standard for vehicle safety
between unlicensed use and ITS.
technologies. Thus, many countries that have tested and
C-V2X
deployed DSRC are now assessing C-V2X and exploring
Working through the 3rd Generation Partnership Project, a
options for interoperability and coexistence.
group that coordinates development of wireless standards,
European Union (EU) regulators are encouraging auto and
some telecommunications and automobile companies
telecommunications companies to decide on a single
developed C-V2X in 2017. C-V2X, like DSRC, can operate
solution or to find a way to permit interoperability between
independently from the cellular network for V2V and V2I
DSRC and C-V2X. ETSI, a European standards
communications, but can also connect to 4G and 5G
organization, is exploring ways for the two technologies to
networks. 5G networks, once fully deployed, are expected
interoperate or coexist in the same band, with findings
to offer high-speed, low-latency (i.e., reduced lag time)
expected in 2022. If no technology resolution is found in
services, critical for safety applications and autonomous
the next two years, EU regulators expect to choose between
vehicle operation. The 5G Automotive Association
DSRC and C-V2X. Until then, EU regulators have chosen
(5GAA), which includes some automakers, technology
to allocate spectrum to both DSRC and C-V2X. Some
companies, telecommunication providers, and standards
member countries prefer one over the other, and some
bodies, asserts that C-V2X performs better than DSRC and
cross-border corridors are deploying DSRC (called ITS-G5
that its adoption will accelerate the deployment of
in Europe), and others, C-V2X. Volkswagen is selling
compatible 5G systems, including traffic lights, traffic
several vehicles equipped with DSRC, while BMW and
control systems, and personal devices. In 2018, 5GAA
Mercedes reportedly favor C-V2X but have yet to install it
petitioned the FCC for spectrum in the 5.9 GHz band to
in their vehicles. The EU allocated 40 MHz for vehicle
deploy 4G-based C-V2X; deployments have been limited to
safety technologies, with an adjoining band of 10 MHz used
a few cities. In contrast to DSRC, 5G-based C-V2X
by urban rail that can also be used for road ITS (Figure 1).
standards and test procedures have not been finalized.
Policy Considerations
Figure 1. U.S. and EU Spectrum Choices
Policy considerations center on spectrum and standards
decisions, and U.S. competiveness in the global automobile
and wireless technology industries.
Spectrum Decisions and Interference Concerns
A challenge for Congress is balancing competing spectrum
needs. In a letter to the FCC, sent before it made its
decision, DOT disagreed with the FCC’s proposal to split
the band, asserting that 30 MHz is insufficient for safe ITS
use. DOT cited industry tests showing interference potential
from unlicensed devices operating in the lower band, and
argued that the FCC’s technical requirements for use of the
band do not resolve DOT’s interference concerns. Further,
Source: CRS.
DOT stated that the entire band will be needed as
Japan and South Korea—other major auto-producing
autonomous vehicles come into use. The FCC stated that
countries that had previously planned on adopting DSRC—
the band is underutilized and it is in the public interest to
have C-V2X testing underway and remain undecided on
reallocate a portion for consumer use. During the COVID-
spectrum allocation and vehicle safety technologies.
19 pandemic the FCC granted wireless providers temporary
A key consideration for the U.S. government is China’s
authority to use the lower segment to provide broadband
decision to make C-V2X mandatory. Industry analysts
services. It stated that 30 MHz is adequate for vehicle
expect support for C-V2X in China could drive wide-scale
safety needs, and argued that automakers could use the
deployment there, enabling economies of scale and
unlicensed portion of the band for ITS nonsafety features.
reducing costs, which could spur C-V2X adoption in other
Standards Decision
regions. Some analysts say the FCC’s selection of C-V2X
A second issue is the FCC designation of C-V2X as the sole
could give U.S. technology companies a competitive edge
ITS technology that can operate in the band. In effect, the
in the global C-V2X market, while DOT asserts the FCC
FCC selected C-V2X as the U.S. standard for vehicle safety
has abandoned safety technologies that can save lives now.
technologies. This is a departure from past practice, under
which the agency has generally refrained from designating
Bill Canis, Specialist in Industrial Organization and
a specific technology. The FCC says its selection of C-V2X
Business
could spur investment in C-V2X technologies, improve
Jill C. Gallagher, Analyst in Telecommunications Policy
roadway safety, and strengthen U.S. competitiveness in the
IF11260
https://crsreports.congress.gov
Smart Cars and Trucks: Spectrum Use for Vehicle Safety
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https://crsreports.congress.gov | IF11260 · VERSION 3 · UPDATED