DSRC vs. Wi-Fi – Let the Games Begin!

This summer, many competition-hungry spectators will flock to Rio for the Olympics. But others may prefer to stay home and watch a different competition unfold: the Spectrum Olympics, pitting Dedicated Short Range Communications (DSRC) against Wi-Fi. The prize? Determining how best to share the 5.850-5.925 GHz band (also referred to as the "U-NII-4 band").

Two years ago we reported on the growing interest in deploying Wi-Fi on the U-NII-4 band which had been set aside back in 2004 for DSRC. DSRC was authorized for vehicle-to-vehicle and vehicle-to-infrastructure (roadside sensors) wireless communications, with the idea of making our highways safer. But the automobile industry has been slow to develop the technology. Cadillac plans to introduce the first car with DSRC technology this fall, although it may have nothing to communicate with.

The DSRC band is immediately adjacent to the 5.725-5.85 GHz band used by Wi-Fi systems. The Wi-Fi industry has seized on DSRC delays as an opportunity to expand their spectrum. And they've gotten some pretty powerful fans. Commissioners Rosenworcel and O'Rielly posted a blog post on the FCC's website last year calling for Wi-Fi sharing of the DSRC band, while Commissioner Pai also has publicly supported the concept.

The Commission has engaged in discussions with the Department of Transportation (DOT) on how to manage the band. Now, having put pressure on the automakers for some time and having in turn received pressure from Congress, the Commission has released a Public Notice seeking:

• Comments on two distinct band-sharing proposals floated by the Wi-Fi industry. The first, promoted by Cisco, would allow unlicensed users to use "detect and avoid" technology to access the band at places and times when DSRC is not in use. The second, promoted by Qualcomm, would "channelize" the band by moving "safety-related" DSRC to a segment at the top of the band (5.895-5.925 GHz), leaving the lower portion to be shared between non-public safety related DSRC and Wi-Fi via standard 802.11 protocols (including the technology currently used between Wi-Fi devices to detect available channels). The Commission is seeking comment on the advantages and disadvantages of both approaches, including the technical rules or studies needed.
• The submission of prototypes of DSRC devices, preferably by July 30, 2016, that it can use in joint testing.
• Comments on a proposed test plan that the FCC developed with the DOT and the NTIA (the managers of the federal spectrum) that would "complement" and be independent of a test plan announced last year by DOT. Testing would be conducted first at FCC Labs, and then in two different stages in the field using actual vehicles. The Commission seeks comment on all phases of the proposed tests, as well as on the merits of its proposed January 15, 2017 end date for testing.

The automotive industry has been fighting against sharing generally. It's particularly against the channelization approach because industry participants claim that they are already far advanced in designing DSRC systems that will operate across the entire band and would not be able to change system designs at this late date. In its Public Notice the Commission asks detailed questions to get at the merits of the industry's claims.

For those interested in weighing in on who should get the gold medal in this Spectrum Olympics, the Public Notice has been published in the Federal Register, thereby establishing July 7, 2016 as the comment due date and July 22, 2016 as the reply comment due date. You can submit your comments at this FCC website; enter Proceeding Number 13-49.