Prototype spectrum-sharing devices “reliably detected” DSRC signals — but where will FCC go from here?
The Federal Communications Commission’s Office of Engineering and Technology has released testing results which show that prototype devices can successfully share 5.9 GHz spectrum that is currently allocated to Dedicate Short Range Communications for vehicle-to-everything use — but the FCC now appears more interested in the potential reallocation of the band rather than the DSRC/Wi-Fi spectrum-sharing framework that the testing was designed to explore. Two commissioners have called for a new rulemaking to reexamine how the 5.9 GHz band is allocated.
The coexistence testing was first called for in 2016, and results were made public yesterday after having been submitted to the Commission earlier this year.
“The reality is that the entire debate has gravitated away from the type of sharing regime envisioned in the testing,” Commissioner Michael O’Rielly said in a statement. “Instead, the Commission should move past this and initiate a rulemaking to reallocate at least 45 megahertz of the band, which is completely unused today for automobile safety.”
Commissioner Jessica Rosenworcel noted in her statement that the results came nearly two years after the deadline that had originally been set for for completing a three-phase test plan to determine whether V2V communications and Wi-Fi could share the 5.9 GHz band.
“These results are long overdue,” Rosenworcel said. “But we need to do more than just make our work public. We need to start a rulemaking to take a fresh look at this band and its real possibilities.”
Rosenworcel has previously made public statements about possibly looking at 5.9 GHz for unlicensed use and next-generation Wi-Fi and that she has worked with O’Rielly on this issue. O’Rielly has mentioned in public appearances, including at this year’s Connectivity Expo, that one of his goals as commissioner is to open more mid-band spectrum and ensure the availability of additional unlicensed spectrum.
Although there have been some token moves by automakers to begin utilizing the DSRC band, it remains largely unused almost two decades after being set aside for V2V communications. Toyota in particular has strongly backed DSRC and has said that it will start deploying the technology in Toyota and Lexus vehicles in 2021. In August, the auto maker invited its Ann Arbor, Michigan-area research and development team and their families — about 1,800 people — to have their personal vehicles outfitted with DSRC technology in a large-scale local pilot program. GM, meanwhile, has made DSRC standard in its Cadillac CTS sedan in the U.S. and Canada for the interim 2017 model year. The Obama administration had a federal mandate in process to require the inclusion of DSRC technology on new vehicles, starting as soon as 2020 — but the mandate was put in limbo when the Trump administration took over, and the current administration has since backed away from any action on such a regulatory requirement. In the meantime, alternatives such as cellular V2X have flourished.
In terms of the actual coexistence testing, the FCC said that it performed about 1,450 individual tests and collected more than 1 million data points to assess whether Wi-Fi and DSRC could share the 75 MHz of DSRC spectrum. The lab test results “provide baseline data for performing analysis of additional operational scenarios and other ‘real-world’ empirical tests as part of the future phases of the coexistence test effort,” according to the report — that is, if the coexistence test effort continues.
The testing explored two possible spectrum-sharing approaches: detect-and-vacate or re-channelization, as they were called in the report. The FCC described those two strategies as “either vacating the spectrum entirely or sharing a portion of the spectrum with non-safety related communications using techniques similar to Wi-Fi sharing.”
The FCC said that five companies —Â Cisco, Qualcomm, KEA Tech, Broadcom, and CAV technologies — submitted nine devices for coexistence testing. The OET said that Qualcomm, Cisco, KEA, Broadcom, and the Department of Transportation also submitted DSRC devices to use for the testing program.
“The prototype devices reliably detected DSRC signals,” the FCC concluded, going on to add: “In brief, the test results show that the prototype U-NII-4 devices were able to detect a co-channel DSRC signal and implement post detection steps as claimed by the submitters.”
The test results — and the additional two phases of the test program — may end up being moot, however.
The FCC Office of Engineering and Technology itself acknowledged that in the two years since the test plan was announced, the landscape around vehicle communications has shifted considerably.
“We recognize there have been a number of developments since the three-phase test plan was announced in 2016—such as the introduction of new technologies for autonomous vehicles, the evolution of the Wi-Fi standards, the development of cellular vehicle-to-everything (C-V2X) technology, and the limited deployment of DSRC in discrete circumstances,” the OET stated in the public notice accompanying the test results. “We invite comment on how any of these factors or others should impact our evaluation of the test results, our three-phase test plan, or our pending proceeding on unlicensed use in the 5.9 GHz band.”
The FCC is accepting comments on the test results through Dec. 13.
The cable company trade group NCTA recently  called for the FCC to abandon DSRC and open up the spectrum for other uses — Wi-Fi in particular. Recent FCC comments by the Wireless Internet Service Providers Association also support a new proposed rulemaking, saying that the availability of 5.9 GHz spectrum would be “extremely useful for … rural fixed wireless broadband deployments” and that “equipment can be easily adapted to operate in the 5.9 GHz band and quickly deployed.”
Trade group Wi-Fi Forward, for one, was not impressed with the test results. In a statement, the group said, “The results of these tests prove that Wi-Fi can successfully operate in the 5.9 GHz band without causing harmful interference. But the facts on the ground have changed and further testing of co-channel operation with DSRC is no longer relevant. So while some parties will seek years of additional testing to try to stall FCC action, it is now time for the FCC to issue a new further notice that brings Americans gigabit broadband and asks whether it should continue to support the failed DSRC experiment.”
