Recently, the FCC issued a Notice of Proposed Rulemaking (“NPRM”) seeking ways to promote vehicle safety communications and unlicensed uses in the 5.9 GHz band.  That band was originally allocated for vehicle safety communications but has not been widely used.

By way of background, some two decades ago, the Commission allocated the 5.9 GHz band for a vehicular safety-related service called Digital Short-Range Communications (“DSRC”) and established rules and protocols therefor. DSRC has never caught on, and, in in an initial effort to promote better utilization of the band, in 2013, the FCC issued an NPRM proposing to reallocate it to unlicensed uses as well as DSRC.  Since then, automakers have continued largely to ignore the 5.9 GHz band and have used other spectrum systems as well as LIDAR (light detection and ranging) for vehicular radar. Such radar is used for adaptive cruise control, automatic braking and other collision avoidance systems. It is also an important component of automated vehicles.  The FCC never adopted the proposals in that first NPRM and allowed the docket to remain open.

In order to see if the 5.9 GHz band could be used more efficiently, in December, the FCC issued a second NPRM proposing to allow a technology called Cellular Vehicle to Everything (C-V2X), which would essentially create a connected vehicle ecosystem, as well as to unlicensed uses to operate in the band.  Under the proposal, forty-five MHz in the lower portion of the band would be allocated to unlicensed uses, and 30 MHz in the upper portion would be allocated to vehicular communications.  The NPRM asks whether 10 MHz in the upper portion of the 5.9 GHz band (5.85-5.905 GHz) should continue to be set aside for DSRC or whether it would better be used for C-V2X.

The spectrum to be set aside for C-V2X could be used for vehicle to vehicle communications (“V2V”), vehicle to roadside infrastructure (“V2I”) for traffic and road safety purposes, as well as cellular communications (“V2N”).  The advantages of using the band for vehicle to cellular communications, as opposed to DSRC, include the fact that it is not limited to line-of-sight, that it is less prone to interference, and that it would allow adaptation to evolutionary changes such as 5G.

With respect to unlicensed services, the NPRM proposes technical rules and out-of-band emissions limits for operations in the 5.9 GHz band.  The rules are similar to those applicable to U-NII devices and require those devices to accept interference from licensed users.

The proposed rules would also protect both incumbent Federal radar users and private fixed satellite operators from interference by continuing to require coordination zones in the vicinity of protected sites.  The NPRM does, however, ask whether it might be possible to adopt technical rules – such as requiring reduced power when operating near protected sites – rather than requiring compliance with the existing geographical limits.

A recent development suggests the Commission is on the right track in promoting C-V2X in the 5.9 GHz band.  Audi, Qualcomm and the Virginia Dep’t of Transportation were granted an experimental license to conduct C-V2X trials in the band “to demonstrate work zone warnings and ‘signal phase and timing’ systems”. According to the press release, “C-V2X will send graduated warnings of live work zones to vehicles…[and] it will also provide green light countdowns to vehicles directly from traffic signals.”

We would be pleased to advise any entities contemplating using the 5.9 GHz band, whether on a permanent or experimental basis, of the current requirements for operating in the band as well as the implications of the FCC’s recent proposals.