DSRC Supporters, Wi-Fi Advocates Disagree on 5.9 GHz Band Path

Supporters of dedicated short-range communications (DSRC) technology say the FCC must continue planned testing of 5.9 gigahertz band coexistence with Wi-Fi devices, while some Wi-Fi advocates say the results of the first round of tests validate their call for the Commission to move ahead with a rulemaking to open spectrum to unlicensed devices.

Comments were filed by yesterday’s deadline in ET docket 13-49 on a report released by the FCC’s Office of Engineering and Technology last month that concluded that prototype unlicensed devices were able to detect 5.9 GHz band DSRC signals in testing in the FCC’s lab (TR Daily, Oct. 29).

The report concluded “that the two proposed interference mitigation methods, Detect-and-Vacate and Re-channelization proposals, offer a means for U-NII-4 devices to coexist with DSRC devices.”

In their comments, entities emphasize different parts of the report most favorable to their positions.

The testing was conducted in Phase I of what has been scheduled to be three phases of testing, with the last two in the field. The FCC had planned to complete all three phases by January 2017, but the second two phases have yet to begin. OET asked for comment on the test results as well as whether developments in the industry since the three-phase test plan was announced in 2016 should impact the way the agency evaluates the test results.

DSRC supporters urged the FCC to continue the testing in the second and third planned phases and emphasized DSRC deployments that have occurred since the testing was announced. They also cited that the U.S. Department of Transportation and its National Highway Traffic Safety Administration have stressed the importance of conducting all three phases of testing and noted the more than 70 active vehicle-to-everything (V2X) deployments.

“This three-phase collaborative test program involving the FCC, U.S. DOT and the National Telecommunications and Information Administration (NTIA) to explore sharing in the 5.9 GHz spectrum band with unlicensed devices is interdependent, and all three phases are necessary to determine the viability of allowing unlicensed devices to share the spectrum in the 5.9 GHz band with the incumbent designated uses supporting automotive safety,” the Alliance of Automobile Manufacturers said in its comments with the FCC. “Each phase of testing relies on the other phases to provide requisite data needed for meaningful comparison and evaluation, and to determine how best to proceed with interference-avoidance and allocation of spectrum use rights in the 5.9 GHz band. Also, the introduction of new technologies since the 2016 FCC announcement of the three-phase test plan does not lessen the necessity to complete each phase. Therefore, it is essential that the FCC continue its three-phase testing plan. All three phases are necessary to show whether unlicensed devices can safely operate in the 5.9 GHz spectrum band without harmful interference to incumbent technologies that support automotive safety.”

“While the findings in OET’s Phase I testing report stipulate that both sharing proposals (detect and vacate and re-channelization) are able – in a limited laboratory testing setting – to successfully detect a DSRC signal and implement post detection steps as initially proposed, OET notes that Phase I investigated the feasibility of the two proposed interference mitigation strategies in a controlled laboratory environment and not in an outdoor setup representing real life scenarios,” the alliance added. “Additionally, OET observed that re-channelization affords a higher probability of transmission to DSRC devices during co-channel operation, and that there are also potential risks of interference during adjacent channel operation for both sharing proposals. Potential decisions regarding lifesaving safety capabilities are at stake based on this incomplete three-phase testing process. We strongly oppose the FCC relying only on limited phase I laboratory test results for decision making in its proceeding on unlicensed use in the 5.9 GHz band. Until the joint FCC, DOT and NTIA testing under phase II and phase III is completed, it would be premature to make a judgment about reallocating this safety-critical spectrum. The Alliance strongly encourages the Commission to complete its three-phase test plan to gather data from field testing and real-world scenarios to determine whether sharing within the spectrum band will cause harmful interference to incumbent uses and technologies that support automotive safety.”

The alliance also said that the FCC should not reallocate any of the spectrum unless the test “results clearly indicate that sharing can occur without harmful interference to the incumbent technologies or other intelligent transportation systems technologies.”

“Given the importance of data-driven policymaking in areas affecting safety-of-life communications like those provided by DSRC, Global Automakers urges the Commission to continue with Phase II and Phase III testing as planned before allowing any unlicensed use of the 5.9 GHz band,” said the Association of Global Automakers, Inc.

“In conjunction with the delay in conducting the Phase I testing and production of the report, there have been several important developments with respect to vehicle-to-everything (‘V2X’) technology and the future of the 5.9 GHz band since the adoption of the test plan. DSRC has been more fully deployed and more major commitments announced, and a second V2X technology – cellular V2X (‘C-V2X’) – has emerged,” the group added. “These developments manifest robust market demand for V2X services. Indeed, in the face of an eleventh-hour request that the 5.9 GHz band be reallocated just as V2X services are being deployed, the entire auto ecosystem, including the U.S. Department of Transportation (‘DOT’), has unified in its position that the entire 5.9 GHz band – all seven channels – must be preserved for V2X auto safety services. Indeed, as discussed herein, it is not clear that any party continues to support the re-channelization proposal evaluated in Phase I. The FCC should inquire as to whether there is continuing interest in re-channelization before evaluating it further, particularly in light of the possibility of multiple V2X technologies using the band.”

The re-channelization proposal was driven by Qualcomm, Inc., which did not file comments in response to the test report.

“Nevertheless, given the importance of V2X technologies to the future of transportation and the life-saving safety benefits V2X brings to our nation’s roadways, it is essential that any changes to the allocation and channelization of the 5.9 GHz band to allow use of the band by U-NII devices be based on rigorous, empirical testing that has conclusively determined that U-NII operations can be conducted without interfering with V2X operations,” the Association of Global Automakers added. “OET’s Phase I testing provided useful information about the potential for sharing between DSRC and U-NII operations in the 5.9 GHz band, particularly as regards ‘Detect-and-Vacate.’ But there is more to be done to validate either of the sharing methods identified by the Commission and provide the empirical evidence necessary to support sharing.”

“While the Phase I test report does not draw conclusions about whether either of the two tested sharing approaches can reliably avoid harmful interference to DSRC, it does present empirical evidence of such interference in the case of the ‘re-channelization’ approach. In fact, the Phase I test results indicate both cross-channel and co-channel harmful interference with potentially significant implications for incumbent DSRC operations in the band,” said Toyota Motor North America, Inc.

“Because the Phase I test results suggest the presence of harmful interference, the Commission must remain committed to additional phases of testing before proceeding with any decision to open the 5850-5925 MHz band to U-NII devices,” Toyota added. “Field testing in real-world environments is essential to analyzing and quantifying the interference potential introduced to DSRC from unlicensed use in the band. To that end, future phases of testing should incorporate additional scenarios and factors not considered in Phase I that will better emulate the conditions that are likely to be present in the real world. In addition, testing should consider the impairment and degradation of DSRC operations that are likely to occur because of changes required of DSRC under the ‘re-channelization’ approach.”

“We are pleased to see Phase I testing results, and strongly support the continuation of Phase II and Phase III testing,” said General Motors Co.  “Testing should be completed before any unlicensed use of the 5.9 GHz band is contemplated. Further, GM urges that the full 5.9 GHz safety band should be dedicated to vehicle safety technologies with the potential to help prevent a large part of the 37,133 deaths on U.S. roadways last year alone.”

The American Trucking Associations also urged the Commission to continue the testing. “Among the developments since 2016 is the rapid development of driver-assistive truck platooning enabled by DSRC technology,” the group said. “Truck platooning uses V2V [vehicle-to-vehicle] communication to connect the active safety systems – braking, acceleration, and in some cases steering between trucks – allowing them to travel closer together than would otherwise be possible for aerodynamic fuel efficiency. This V2V link, which takes place on DSRC channels – separate from those reserved for other uses – provides a robust, near-instantaneous connection, allowing trucks to react significantly faster than a human or even radar sensors could on their own, thereby suggesting safety improvements beyond conventional trucks on the road today.”

Autotalks Ltd., a designer and manufacturer of connected vehicle technologies said, “While lab tests are an essential first step, those are not enough to make a decision that can impact safety of life. Field tests, using vehicles deployed with V2X, vehicle WiFi hotspots, in-vehicle WiFi devices, and WiFi access points are needed to assure that V2X can operate without any interferences. Acceleration of the tests would be desired to support the existing and planned DSRC deployments, and to provide the required certainty for more OEMs to deploy.” It added that it “agrees that Detect & Vacate scheme is likely to provide protection for DSRC operation, but further measurements are needed to fully validate the scheme.”

ITS America said it “does not support any deviation from the Test Plan to a collateral proceeding examining other outcomes. There is no basis for exploring a band reallocation that would disrupt incumbent users, deter the deployment of life saving systems, delay the development of new and emerging technologies, and otherwise penalize public and private sector interests that have dedicated their scarce resources to improving the safety of our public transportation network.”

The Safety Spectrum Coalition, whose members include auto and truck industry groups, highway users, and AAA, said that it “strongly supports the continuation and expediting of the FCC’s efforts to test spectrum sharing to determine if unlicensed devices such as Wi-Fi can safely share the 5.9 GHz band with V2X operations without harmful interference. There have been significant investments in DSRC technology by many entities in both the public and private sectors, relying on the allocated spectrum and current channelization. Further delays in completion of the spectrum sharing tests and questions about channel allocation and spectrum rules contribute to uncertainty regarding these and further investments, potentially delaying improvements in safety and efficiency for our transportation system. The Safety Spectrum Coalition firmly believes that evaluating the impacts of sharing, and any potential sharing plan, should work around intelligent transportation operations in the band and not slow deployment of V2X and the realization of its benefits.”

The American Association of State Highway and Transportation Officials said it “recognizes the need to accelerate the time line for performing Phase II and III testing given the delay in releasing Phase I results. To this end, AASHTO is willing to assist USDOT-NHTSA in identifying operational field devices and corridors in real world deployments that could serve as ‘test-cases’ in Phase II of the field testing.” AASHTO also said “that policy decisions related to spectrum reallocation be made only after all three phases of testing are completed and the results are conclusive, and have been made available for public review. This aligns with USDOT’s position as outlined in its recently released AV 3.0 document [TR Daily, Oct. 4]. While the Phase I tests may have shown that unlicensed devices do not interfere with DSRC communications, it is important to qualify that these tests were performed in a controlled environment and the results do not always translate to the real world.”

AASHTO added, “The Commission’s statement accompanying the release of the test results referring to ‘the limited deployment of DSRC in discrete circumstances,’ is notably inaccurate. It fails to acknowledge the efforts of 26 states who, in response to AASHTO’s Signal Phase and Timing (SPaT) Challenge and in an effort to improve transportation safety, committed significant resources to deploying DSRC-enabled equipment at more than 200 traffic signals, with more than 2,100 additional signals programmed for installation in the near future, likely before the end of Phase III. State and local transportation agencies have invested millions of dollars in DSRC, and they do not want the investment in this life- saving technology to be wasted. Therefore, there is an obligation on the part of the Commission to ensure that the effectiveness of the spectrum dedicated for transportation safety and mobility applications is not compromised.”

The Maryland Department of Transportation said it “is at the forefront of adopting the foundational technical critical to the deployment of V2V and V2I [vehicle to infrastructure] and the full band of spectrum is needed to allow these safety applications to achieve their great potential. Preserving the entire 5.9 Ghz DSRC allocation will allow these technologies to progress and provide states with the necessary means to protect travelers on public roads and promote transportation efficiencies.”

“The first phase of FCC’s study is quite limited in scope and therefore does not address many of the questions regarding the efficacy of detect-and-vacate or re-channelization,” said the Motor & Equipment Manufacturers Association. “Since any lost V2V Basic Safety Messages could result in a collision, significant additional studies will be required to evaluate these spectrum sharing methods. Therefore, MEMA recommends that the FCC, DOT, and DOC continue and complete the 3-Phase Test Plan regarding spectrum sharing technology. In the interim, MEMA continues to urge the FCC to preserve the 5.9 GHz spectrum designation and channelization features as they exist today for DSRC, which is a critical vehicle safety technology.”

“We look forward to FCC following through with the remaining two planned test phases to fully evaluate potential sharing solutions for the 5.9 GHz,” the Truck and Engine Manufacturers Association. “In particular, FCC should work closely with DOT in field testing of unlicensed devices in actual vehicle operations and subsequently in a wide variety of real-world environments. Any potential sharing solutions must be thoroughly validated before permitting unlicensed devices to share any frequency in the 5.9 GHz band. It is critically important that FCC only permit sharing if it will not interfere with the timeliness and reliability of vehicle safety communications.”

The OmniAir Consortium, Inc., whose members include transit authorities, said that “it is still premature for the Commission to make a final determination that spectrum sharing in the 5.9 GHz Band can be realized while protecting critical transportation safety messages from harmful interference. OmniAir encourages the Commission to conduct the planned Phase II and Phase III testing as soon as possible. Ultimately, any Commission decision needs to ensure that there is ‘safe’ spectrum for V2V communications regardless of the underlying radio technology.”

Panasonic Corporation of North America said, “Preserving the entire 5.9 GHz band for transportation and vehicle safety applications holds enormous potential to save American lives and enable the deployment of an ‘internet of roads’ to improve the efficiency of transportation infrastructure. Panasonic encourages the Commission to cooperate with DOT to promptly commence Phase II testing to ensure that any unlicensed use in the band occurs without harmful interference to incumbent and future intelligent transportation systems technologies.”

Aptiv PLC, an auto parts company that has deployed devices for V2V safety and V2I smart city initiatives, expressed “the need for the FCC and USDOT’s Intelligent Transportation System band to remain intact for DSRC use only, and launched per current USDOT and US transportation industry full use initiatives to implement the critical US life/crash savings and modernization needs for which it is designed. Aptiv recommends the FCC further evaluate the spectrum requirements of the new C-V2x technology based on full US deployment scenarios and expected vehicle life cycle.”

DENSO International America, Inc., a supplier of auto technology, systems, and components, encouraged “the Commission to continue with Phases II and III of the test plan before making any decisions that would impact the future of these technologies.”

The IEEE 1609 Dedicated Short Range Communication Working Group said urged the FCC “to use Phase II and III testing to explore more realistic outdoor scenarios and topologies, including the case of a high power Wi-Fi hotspot next to a road or intersection. We see clear signs of cross-channel and co-channel interference in the Phase I report. We think the developments in the industry since the 2016 Public Notice only reinforce the three-phase test plan. Finally, we urge the Commission to use certified and standards-compliant DSRC devices when possible.”

“The results of your Phase 1 testing show that spectrum sharing might be technically feasible, but the original test plan set out a three-phased approach, and we strongly encourage the FCC to follow-through on its commitment,” the Institute of Transportation Engineers said. “The public release of these results included recognition by the FCC that there have been a number of developments since the original test plan was announced, which is all the more reason to continue with your planned approach.”

But NCTA said in its comments that OET’s “extensive tests of Wi-Fi devices’ ability to coexist with Dedicated Short Range Communications (DSRC) operations in the 5.9 GHz band were a success. The test Report further clears the path to resolving this long-running proceeding. The time has come to issue a Further Notice of Proposed Rulemaking (FNPRM) proposing to open the band to unlicensed operations.”

“As the Phase I Public Notice recognizes, ‘there have been a number of developments’ even since testing began in 2016,” NCTA added. “Consumer demand for Wi-Fi has continued to expand, creating an impending spectrum crunch, while DSRC has not deployed as the Commission expected when it established the rules for this band. There has also been immense investment in the next generation of broadband, including Gigabit Wi-Fi and 5G, which will be compromised without near-term access to additional unlicensed spectrum. Accordingly, OET now seeks comments on how these changed circumstances ‘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.’ Given the facts on the ground, NCTA recently requested that the Commission issue an FNPRM or other appropriate vehicle to take a ‘fresh look’ at the 5.9 GHz band and propose to designate all or a substantial portion of the band for unlicensed use [TR Daily, Oct. 16]. OET’s Report further confirms that the Commission can and should issue this FNPRM without further delay.

“In particular, the Report demonstrates that Wi-Fi devices can avoid harmful interference with DSRC devices in adjacent channels,” NCTA added. “Regardless of whether the 5.9 GHz band is ultimately the right home for automotive-safety operations, this key finding supports any effort by the Commission to propose a band segmentation approach that would designate a portion of the band for Wi-Fi and a portion for DSRC or future Intelligent Transportation Systems (ITS) technologies. Should the Commission propose to reserve a portion of the band for safety-of-life DSRC uses, the Report’s adjacent-channel interaction results show that the Commission can place Wi-Fi and DSRC on adjacent channels without significantly impacting the efficacy of DSRC systems.”

The Wi-Fi Alliance said it “is particularly encouraged that the test results confirm the U-NII-4 prototypes’ ability to detect DSRC signals and implement the post detection steps. These results amply demonstrate Wi-Fi industry’s commitment to invest in technological development to meet the Wi-Fi ecosystem’s expanding needs for additional spectrum capacity. In light of that, Wi-Fi Alliance urges the Commission to expeditiously resolve remaining regulatory issues and to allow unlicensed use in the U-NII-4 band.”

Cisco Systems, Inc., which submitted detect-and-vacate prototype devices for testing, said that questions remain concerning the re-channelization proposal. “By contrast, there is nothing in the report that indicates that the Phase 1 tests or the testers were left with gaps in their understanding of how the detect and vacate method worked, at least within the bounds of the Phase 1 testing scope,” Cisco said. “This statement is not meant as a qualitative assessment of the two methods, but as an observation that detect and vacate presents a more straightforward path to testing than re-channelization. This difference needs to be kept in mind moving forward, as testers need to continue to consider what they do not know or what the tests will not reveal about the methods presented.”

Cisco also stressed that “C-V2X is [in its] early days. Not only does the technology need to be tested by government agencies and automobile manufacturers to ensure it can perform at least as well as DSRC under all reasonable conditions, there are a number of significant questions that remain entirely open about whether C-V2X can support an ecosystem that will contribute to road safety in the same way that DSRC has been designed to do.”- Paul Kirby, paul.kirby@wolterskluwer.com

Courtesy TRDaily