The ability of vehicles to communicate their location, direction
of travel and speed data to other nearby vehicles
(vehicle-to-vehicle communications or V2V) will significantly
augment the safety gains associated with autonomous vehicle
technologies. While the autonomous vehicle uses vehicle-based
devices like cameras and sensors to "see" the environment
around the vehicle and avoid potential incidents, V2V
communications provide additional information about other potential
vehicle threats that the vehicle-based devices cannot yet see.
However, while V2V technology is already being deployed throughout
the U.S., the effectiveness of those deployments may be impaired by
another, yet-to-be fully developed technology based on 5G cellular
communications.
In January 2017, the National Highway Traffic Safety Administration
issued a Notice of Proposed Rulemaking (NPRM) for V2V
communications. The NPRM proposed to require the adoption of
designated short range communications (DSRC) technology to enable
such communications. Using DSRC devices, cars would be able to
communicate basic safety messages (BSMs) directly with each other
(not through a cellular base station), which would, among other
things, warn a vehicle receiving a BSM of an impending collision.
Under the NPRM, DSRC devices would operate in the 5.9 GHz spectrum
that had previously been set aside by the FCC for that purpose. The
NPRM did not foreclose the eventual use of other technologies in
that spectrum, provided the technologies were interoperable with
DSRC. Interoperability means "the ability of the DSRC devices
to decode at least one mode of transmission by the other technology
devices and of the other technology devices to decode
DSRC."1 That is, the two devices would have to be
able to talk to each other, not just amongst themselves. Progress
on this NPRM stalled in the Trump administration.
The 5.9 GHz spectrum consists of seven 10 MHz wide channels. DSRC
uses all seven channels. Two of the channels, 172 and 184, were
designated for "safety of life and property
applications."2 These are the crash avoidance and
mitigation applications. Four of the remaining channels were
designated as service channels to support related
vehicle-to-everything (V2X) applications. The last channel, 178,
was designated as a control channel.
For the past several years, the FCC has been aggressively
undertaking to free up bandwidth for future 5G wireless
communications. Its efforts have included reconfiguring bands;
auctioning spectrum in the upper 37 GHz, 39 GHz and 47 GHz bands;
freeing up spectrum in the 2.5 GHz, 3.7GHz, 4.9 GHz and 6 GHz
bands; and permitting wireless to share other spectrum. One
candidate being targeted for sharing is the 5 GHz spectrum,
including the 5.9 GHz band currently designated for DSRC.
In 2016, the FCC commenced a three-phase test program to determine
whether unlicensed (e.g., cellular) and DSRC networks could operate
together in the 5.9 GHz band without causing harmful interference
with DSRC communications. The results of the first phase of testing
were finally published in late 2018.3 The second and
third phases are pending.
Presently, the specific cellular technology being proposed to share
the 5.9 GHz spectrum with DSRC is LTE-V2X or cellular V2X (C-V2X).
It is projected that the 5G version of this technology, 5G-V2X or
New Radio V2X, will ultimately replace the C-V2X technology. Unlike
DSRC, which is a thoroughly vetted and proven technology for V2X
communications that is already being deployed in locations around
the U.S., field studies of C-V2X have only recently begun. Ford,
along with Panasonic and Qualcom, began deployment and testing of
C-V2X in Colorado in 2018. The 5G network does not yet exist and 5G
V2X is under development.
There is an issue with the C-V2X technology. It is not
interoperable with DSRC – it can only communicate with other
C-V2X equipped vehicles. C-V2X and DSRC are fundamentally
different, non-interoperable technologies. The proposed 5G New
Radio technology has two issues. It is not interoperable with DSRC
or C-V2X. In contrast, the next generation of the DSRC based
technology (called NGV) will be fully interoperable with the
previous generation DSRC. Non-interoperability of communications
technologies results in fragmentation of the vehicle population and
significantly decreases the effectiveness of V2V
communications.
Solutions for the interoperability problem proposed by the cellular
industry include dedicating part of the 5.9 GHz spectrum for use by
DSRC and a separate part for C-V2X (channel separation) and
requiring V2X on-board units (radios) to have two or more separate
radios and antennas, one for DSRC and another for C-V2X (and/or 5G
NR). Critics of these proposals cite concerns with interference,
congestion-related latency issues, inefficient use of spectrum and
increased cost.
Last November, the 5G Automation Association (5GAA) petitioned the
FCC for a waiver to use the upper 20 MHz of the 5.9 GHz spectrum
for C-V2X and later, 5G communications. The request has faced
significant criticism. Many commenters noted that the waiver
process was not the proper tool to use to partition the spectrum.
Rather, formal rulemaking is required. Some also suggested that
5GAA should apply for an experimental license like the one Ford
obtained for its Colorado testing. The petition remains
pending.
Apparently sensing an opportunity with a receptive FCC, 5GAA
recently lobbied the commission to banish DSRC to only one of the
seven 10 MHz bands in the 5.9 GHz spectrum while allowing the
nascent C-V2X technology to operate in the other six "to
achieve its evolutionary path to 5G."5,6
The request is certainly premature. And, given that at least one of
5GAA's automotive members began installing DSRC radios in their
luxury vehicles in 2017, it is potentially at odds with the
interests of at least that member.
So, what is the disconnect? DSRC is an existing V2X communications
technology that is currently being deployed in the U.S. by numerous
communities, Municipal Planning Organizations and Infrastructure
Owners and Operators. It is a proven technology and is presently
the only technology authorized to use the 5.9 GHz spectrum.
However, proponents of 5G, with the assistance of a supportive FCC,
are seeking to co-op the "safety of life" spectrum for
the exclusive benefit of their own future untested commercial
communications technology services at the expense of both DSRC and
those state and local agencies implementing DSRC-based V2X systems.
The technology is available for use and is being used, but might
get shoved aside for commercial reasons unrelated to motor vehicle
safety. An indication that this may be occurring is that Toyota
recently informed the FCC that it is pausing its previously
announced deployment of DSRC devices in its vehicles because of a
perceived lack of commitments to the technology from other
automakers and the "uncertain and unstable" regulatory
environment concerning the 5.9 GHz band.7
1 Comments of IEEE 802 LAN/MAN Standards
Committee, February 21, 2019 on DOT's request for comment on
V2X Communications, December 26, 2018.
2 FCC Public Notice FCC 16-68, June 1, 2016.
3 This study is being conducted under an experimental
license from the FCC.
4 In its petition, 5GAA touts itself as a "Global
cross-industry organization of companies from the automotive,
technology and telecommunications industries." Members from
the automotive industry include Ford, GM, BMW, Daimler, and Nissan
among others.
5 Letter from Wilkinson Baker Knauer, LPP, on behalf of
the 5GAA, to Marlene Dortch, FCC dated April 3, 2019 p.11.
6 The use of the term evolutionary path seems to
disregard the fact that C-V2X and 5G are not interoperable with
each other.
7 Letter from Hillary Cain, Toyota to Marlene Dortch,
FCC dated April 26, 2019. (GN Docket No, 18-357)
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