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From page 67... ... Page 67 V2X COMMUNICATIONS IN THE 5.9 GHZ SPECTRUM: New Directions, Opportunities, and Challenges Contents Summary ..................................................................................................................................................... 68 Introduction ................................................................................................................................................ 69 Section 1 ‐ The NPRM Process .................................................................................................................... 71 Public Comment Periods (January to May 2020) .................................................................................... 71 Post‐Comment Period Submissions (May to October 2020) Read the entire page →
From page 68... ... Page 68 V2X COMMUNICATIONS IN THE 5.9 GHZ SPECTRUM: New Directions, Opportunities, and Challenges Summary This white paper is the second in a series focused on the 5.9 GHz spectrum and the important role it has played -- and will continue to play -- in achieving the many safety and efficiency goals originally established when 75 MHz was first dedicated to intelligent transportation system (ITS) services and applications such as vehicle‐to‐everything (V2X) Read the entire page →
From page 69... ... Page 69 Introduction Connected Vehicle (CV) technologies enable all types of vehicles, infrastructure, and mobile devices to communicate and share vital transportation information. CV technologies will help achieve significant safety and mobility benefits, both on their own and as complementary technologies when combined with in‐vehicle sensors supporting advanced driver assist functions. Several new and evolving mediums, including dedicated short‐range communications (DSRC) Read the entire page →
From page 70... ... Page 70 paper is intended for use by its project panel and state DOT leaders. The objectives of NCHRP 23‐10 are to help inform state DOT efforts for policy development, strategic planning, and infrastructure investment decisions. The project focuses on an evaluation of implications for state DOTs of the FCC proposal to reallocate portions of the 5.9 GHz bandwidth to non‐transportation purposes. For more information, visit the project web page at https://apps.trb.org/cmsfeed/ TRBNetProjectDisplay.asp? ProjectID=4902. NCHRP produces ready‐to‐implement solutions to the challenges facing transportation professionals. NCHRP is sponsored by the individual state DOTs of the American Association of State Highway and Transportation Officials (AASHTO) Read the entire page →
From page 71... ... Page 71 Section 1 ‐ The NPRM Process In late 2019, then FCC Chairman Ajit Pai announced that the Commission intended to release a Notice of Proposed Rulemaking (NPRM) under Docket 19‐138 that would reallocate more than half of the 5.9 GHz transportation safety spectrum for unlicensed uses. The NPRM was approved in late December 2019 and published at the beginning of 2020. After a lengthy comment period and further industry discussion, most elements of the NPRM were presented and approved in November 2020. However, the resulting action has not yet been published at the time of writing, and regulatory uncertainty continues. This section will provide a refresher on the NPRM and highlight the resulting process. Public Comment Periods (January to May 2020) Read the entire page →
From page 72... ... Page 72 encouraged the provision of bandwidth for both technologies. This indicated that for the majority of transportation stakeholders, the technology choice is not as important as making sure adequate spectrum is available to support transportation safety. Post‐Comment Period Submissions (May to October 2020) After the public comment periods closed, there were many additional submissions to the docket and meetings with FCC staff that were intended to influence what the FCC adopts and how industry responds. These actions are summarized in this section. Transportation Experts Remain Strongly Opposed to NPRM Since the end of the reply comment period, many meetings between FCC staff and transportation stakeholders have taken place. Due to the COVID‐19 pandemic, a majority of these meetings have been virtual. In addition, submissions by stakeholders to the docket have continued, providing additional input for FCC staff to consider in their deliberations. The Alliance for Automotive Innovation presented a build‐out schedule for V2X, based on the condition that the FCC would retain the full 75 MHz of spectrum in the 5.9 GHz band: "If the FCC assures that all 75 MHz of spectrum will be maintained for transportation safety and takes action to permit cellular vehicle‐to‐everything (C‐V2X) Read the entire page →
From page 73... ... Page 73 Another argument made during post‐comment meetings and recorded in ex parte filings was made by Continental Automotive Systems, a Tier 1 OEM supplier, suggesting that safety‐of‐life applications will not be deployable under the FCC's current proposal. Continental explained the purpose of Collective Perception Messages (CPM) and Maneuver Coordination Messages (MCM) Read the entire page →
From page 74... ... Page 74 FCC Votes on NPRM (November 2020) Despite vocal opposition from a myriad of transportation stakeholders during and following the FCC's comment period, three elements of the NPRM package were presented and approved at the FCC's Open Commission Meeting on November 18, 2020: 1. Read the entire page →
From page 75... ... Page 75 published, and enacted (60 days after publication) , another 2‐year clock is proposed to begin whereby the upper 30 MHz must become only LTE C‐V2X. Timing and Ongoing Regulatory Uncertainty As noted, the change in Presidential administration, change in party leadership in the Senate, and change in leadership within the FCC could introduce additional implications and outcome scenarios. The FCC is directed by five commissioners appointed by the President and confirmed by the Senate, of which only three can be members of the same political party (which usually means that three are in the President's party and two are in the other major party) Read the entire page →
From page 76... ... Page 76 Section 2 ‐ Immediate Impacts The First R&O, if adopted, will allow immediate access for unlicensed indoor operations across the lower 45 MHz of the 5.9 GHz band. Requests for outdoor unlicensed operations will begin to be considered in some geographic locations, and the clock will begin for ITS licensees to cease use of this portion of the spectrum one year following the effective date. While the R&O signals a clear intent for users to transition from DSRC to C‐V2X in the remaining 30 MHz, the timeline milestone for that to occur is not addressed in the R&O and instead is left open for public comment in the FNPRM. The effects of all these actions transcend far beyond existing deployments, also having impacts on IOOs that are in the process of planning new projects, identifying funding for new projects, and in some instances, currently procuring for new projects. Deployment Issues ‐ Licensing The NPRM began impacting deployment efforts over a year ago, as the FCC first stopped acting on any new license requests or renewals, and then later began to adjust their requirements for what licenses they might consider. It is unknown as of this writing whether additional adjustments will be made by the FCC in reviewing and approving license requests, both during this anticipated R&O publication, as well as post publication. At this stage there are no published reports of license applications being denied, but there are numerous reports of slow responses or no responses to applications having been submitted. While this process continues, there are several possible scenarios where license approval could change, including:  Not approving any further license requests for DSRC, regardless of channel  Approving the use of DSRC only if it is specified to utilized Channel 180  Approving the use of DSRC in any of the upper Channels (180, 182, 184) 57  Approving the use of C‐V2X with an Experimental License for any upper Channel  Approving the use of C‐V2X with a standard license for any upper Channel58 As any license request will be expected to require details related to the geo‐location, mounting heights, and other structural elements, agencies can continue to prepare that information. Details of the specific equipment and requirements of the FCC remain "to be determined," but will likely include information related to power, antenna type and gain, and similar. Deployment Issues ‐ Technology The pauses, restarts, and spectrum battle which currently embroil the CV ecosystem has resulted in a very clear wait‐and‐see attitude for many technology vendors, deployers, developers and more ‐ in particular for the DSRC community. While the investment in new deployments in the past 5 years has demonstrated the commitment and desire of agencies to improve safety, the approach has generally 57 While the current R&O language doesn't explicitly preclude DSRC from using Channels 182 and 184, no known licenses since the Nov. 2019 timeframe have been granted for DSRC on any channel other than Ch. 180. 58 This assume that the R&O and/or Further NPRM will identify the specific requirement to license C‐V2X and discontinue the need for an Experimental License request Read the entire page →
From page 77... ... Page 77 been for vendors to satisfy the immediate needs of the pilots and deployments using 2015‐era technology, allowing agencies to increase their local knowledge, but with the true advancement of the technology and corresponding applications being limited to experimental purposes. Because of the uncertainty of the technology, few vendors continue investing their own dollars to truly mature the technology beyond that current state. C‐V2X proponents and vendors have tried to advance the state of the art with their technology insertion as well, but even the C‐V2X market struggles to make significant headway in the absence of a clear path forward. These challenges will continue to remain for the foreseeable future, but there are actions that agencies can take now that can continue to advance safety, as long as they are undertaken with the knowledge that not all of the investments will realize short‐term benefits and the longer‐term outlook for workforce development and agency readiness continues to be a parallel goal to safety. There are several paths forward for consideration, each with their own pros and cons often unique to the individual IOO and their environment. There is no single best answer, and agencies must consider their own unique situation before deciding how best to move forward. Once again, it should be noted that the following scenarios assume that FCC realignment of the 5.9 GHz spectrum advances. Should it be reversed, then the scenarios will change. Existing DSRC deployments: begin a migratory path to Channel 180 and eventually C‐V2X Agencies with roadside units (RSUs) that are currently operating on any portion of the lower 45 MHz should contact their device vendors and understand what firmware (and possibly hardware) Read the entire page →
From page 78... ... Page 78 with additional months of lead time from the manufacturers once devices are selected and ordered. Once devices are received, testing should be conducted on a sample set to ensure proper operation. Once the IOO has verified device operation, replacement can begin. Replacing DSRC RSUs requires a maintenance or installation crew to remove the DSRC device and install the LTE C‐V2X device. The IOO, or other third party organization, will need to perform system integration and conduct a Final Acceptance Test as outlined in the system Test Plan to verify proper device and system operation. Efforts are currently underway on the part of USDOT, CAMP, the SDOs and industry partnership to ratify the message content, regardless of whether DSRC or C‐V2X are used. IOOs should ensure that there is no divergence from previous outputs as they make this transition, and should ideally look towards the test protocols forthcoming from these efforts. It should also be noted that while C‐V2X is promising, there has not been a large‐scale deployment proof of concept test of the technology like the Safety Pilot Model Deployment or CV Pilots that provided critical deployment and operational lessons for DSRC. Likewise, interference concerns related to adjacent bands not yet been tested, evaluated, or resolved. Depending on procurement, funding schedule, equipment availability, weather, and other constraints, RSU replacement could take a minimum of 12 to 18 months, with system integration taking an additional 6 to 8 weeks after installation depending on the size and complexity of the system. Appendix B provides additional technical detail and process flows for replacing an RSU. Specific to the OBU replacement, the complexity of this action will be directly in proportion to the scope of deployment. Replacing DSRC OBUs will require recalling all equipped vehicles, replacing their devices, and testing the devices to verify they are operating properly. Depending on the size and type of the vehicle fleet, OBU replacement could also take many months following the same logic as RSU procurement, funding, schedule, availability, weather, and other constraints. Replacing OBUs in private citizen vehicles also represents a different set of challenges compared to replacing them in agency‐owned fleet vehicles, and could likely require significant resources to accomplish. Application Issues Impact on applications may vary The specific impacts on applications remains extremely uncertain. In order to properly assess the impact on applications one must first assess the impact on message exchange in a potentially constrained 30 MHz environment. A working group from ITS America has been evaluating this potential scenario for several months.59 They considered numerous V2X applications based on several inputs: spectrum requirements, stakeholder priority, and likely safety benefit. Spectrum requirements were calculated based on assumptions about the number of vehicles within communication range, packet size, repetition rate, 59 https://itsa.org/advocacy‐material/the‐future‐of‐v2x‐30‐mhz‐application‐map/ Read the entire page →
From page 79... ... Page 79 activity factors, spectral efficiency, and channel utilization. The group identified numerous V2X message types and applications that are likely to be deployed: basic safety (BSM) , intersection mapping (MAP) Read the entire page →
From page 80... ... Page 80 Planned V2X deployments: keep moving forward, but emphasize no‐regret investments There are many benefits to continued deployment of V2X communications. For agencies already in the procurement process, consider dual‐mode RSUs or LTE C‐V2X only. However, it is recognized that not every agency can change mid‐procurement, and that stopping a project might jeopardize other elements that could bring benefits, so this recommendation may not apply to all agencies. Continue to emphasize no‐regret elements such as next generation signal controllers, enhanced communications and network architecture, data collection, and security, as well as the potential benefits that can still be garnered through pilot testing and early deployment regardless of radio technology. Device availability and support from vendors may drive this timeline. LTE C‐V2X device availability, licensing, and testing is evolving: build time and cost into projects As noted previously, LTE C‐V2X devices are still in their infancy and have limited availability. The standards are still unfolding, and deployment experience to date has been limited to just a few small‐ scale deployments. Likewise, the licensing process remains uncertain (experimental licenses are assumed as of this writing) , as is the availability of reliable and affordable test equipment. The industry will benefit from its experience with DSRC, but it will take time for best practices to emerge, and for new issues to be worked out at scale. DSRC was still experiencing lessons learned for deployment after 5‐7 years, and a similar timeline is expected for LTE C‐V2X. No‐regret infrastructure investments: many investments will still be usable regardless of the ultimate communications medium Swapping DSRC for LTE C‐V2X requires a new RSU (or simply a new chipset) Read the entire page →
From page 81... ... Page 81 Section 3 ‐ New Research and Ongoing Uncertainty Nearly 20 years have been dedicated to the development and maturation of DSRC as a proven technology. To expect C‐V2X to simply substitute for DSRC without some level of comprehensive field testing, and in a potential single channel configuration, would be shortsighted. LTE based C‐V2X technology and systems need to be thoroughly tested at scale, both for their own functionality, as well as co‐existing with other wireless technologies potentially appearing in adjacent spectrum. Following are several areas which remain high priority for the future of V2X technology. All of these will need to be addressed before the industry can successfully move forward with widespread adoption, and there may be others too. Technical Issues Interference As mentioned several times, it is critical to again emphasize that neither DSRC nor C‐V2X have been subjected to any significant at‐scale testing in a single channel operational environment. For that matter, given that the rules proposed by the FCC for the lower 45 MHz of the band have yet to be finalized, CV vendors remain hamstrung in advancing testing that can truly reflect expected real‐world conditions. At present, CV vendors and researchers must guess what the rules will be, and as identified in White Paper #1 under this NCHRP research, those tests have shown issues with out‐of‐band interference. There has been some speculation that Ch. 180, in the absence of DSRC, would be used as a guard band for LTE C‐V2X, however there has been no definitive decision on this matter. The selection of the 20 MHz Ch. 183 as the primary channel for C‐V2X had more to do with the ability to obtain the experimental license within the 75 MHz ITS Safety Band as the 5GAA could demonstrate limited use of the channel by current DSRC deployments. The original 5GAA Waiver and Band Plan, which has been superseded by the recent FCC plans, allowed for DSRC to retain Ch. 172, but C‐V2X would then occupy the remainder of the spectrum with no guard band, either adjacent to DSRC or on the upper side. While additional research will be necessary to immediately determine the impacts of interference on both DSRC and LTE C‐V2X, a higher‐level review of applications that might remain possible under this reduced scenario will also be an important early step. How many message sets can be exchanged in limited channel arrangements? What tolerance to interference might these messages have, and will this potentially eliminate broad safety‐related applications from consideration (noting that targeted safety applications might still be feasible on a smaller scale) Read the entire page →
From page 82... ... Page 82 limited spectrum is dedicated to safety, and where possible, the operational needs, there will be no spectrum remaining to support complimentary efficiency applications that are a foundation for agencies making the investment. DSRC was designed with seven channels available to address this specifically. The C‐V2X proponents had expected to eventually take control of the middle 40 MHz for use by the next generation or New Radio C‐V2X (C‐V2X NR) to support similar control or over‐the‐air needs. In either case, the 30 MHz remaining only allows for a portion of the vison to be realized, a portion that could end up costing more to implement, and not meet the full expectations originally envisioned. End‐to‐End Security While so much has been focused on the over‐the‐air element of the technology, an often overlooked but very costly endeavor that remains to be addressed in this whole connected ecosystem is the securing of the agency network upon which most of the data will flow. This is critical to not only protect the agency from security breaches but is also critical to ensure that all data provided to vehicles from the infrastructure is legitimate. It is not sufficient to implement digital certificates on the OTA part of this transaction alone, but rather, secure handling of data, starting with its origin, whether that is a signal controller, a traffic management center or other, must be in place. Testing and Application Development The potential changes initiated by the FCC action could result in a total "reset of expectations" in terms of V2X capabilities. Existing pilot deployments are only now making plans to evaluate a single channel DSRC approach. There are a small handful of LTE C‐V2X pilots here in the U.S., but many are still in their early stages and we have little to no results to build awareness of future capabilities. Even the USDOT‐ funded Smart Columbus CV pilot deployment, which will provide a realistic evaluation of a single channel paradigm, is only now just getting ready to launch. The body of knowledge in a reduced‐ spectrum environment does not yet exist, and to date has only been theorized on paper. Given the nature of public agency funding cycles, limited testing opportunities, and unknown equipment needs, a realistic and robust evaluation of longer‐term impacts of this change could be as far as 3 to 5 years in the future. In order to be robust, the efforts would consider the ability for either DSRC or LTE C‐ V2X to exchange multiple message sets in a single channel model, including side‐by‐side and concurrent with adjacent Wi‐Fi operating, and predicated on applications that were originally developed in a multi‐ channel architecture and will need to be re‐engineered. Institutional Issues Further Notice of Proposed Rulemaking The FNPRM addresses several issues not covered in the First R&O. Specifically, they are seeking comments and feedback on: 1. Read the entire page →
From page 83... ... Page 83 When the FNPRM is eventually published in the Federal Register, there is an anticipated comment window of 30 days (based on what was provided with the 2019 NPRM that initiated this action) . A number of important issues should be addressed by all industry stakeholders who will be affected by it. In particular, IOOs will wish to provide comments on: Technology ‐ addressing the uncertainties related to LTE C‐V2X deployment and the time, cost, and resources necessary to "catch up to DSRC" in terms of deployment knowledge; Timing ‐ reinforce the need for existing deployments to have a minimum of 2 years to fully transition from DSRC to C‐V2X, recognizing the inherent challenges with procurement, equipment availability, and deployment resources; Costs ‐ recognizing that for OBU replacement vehicles must be taken out of service and there is both a physical and service cost in doing so. Acknowledging that the equipment costs of changing RSU hardware is often not budgeted in advance which challenges public agency procurement models. And in general, recognizing that who bears these costs is (at this time) Read the entire page →
From page 84... ... Page 84 Section 4 ‐ Impacts to High Priority V2I Applications Understanding the impacts of any spectrum allocation is critically important. As noted in Section 2, ITS America has been working aggressively with industry and other stakeholders to define the priority applications that may remain possible under the new spectrum allocation, and those which appear highly unlikely (based on quantifiable analysis) under reduced bandwidth conditions. Previous efforts by the Cooperative Automated Transportation Coalition (CAT Coalition) Read the entire page →
From page 85... ... Page 85 The RLVW application is also dependent on the MAP message. MAP is typically configured to broadcast at 1 Hz. In addition to SPaT and MAP messages, a location correction message has also been identified as critical to RLVW ‐ the Radio Technical Commission for Maritime (RTCM) message. The broadcast rate for RTCM has not yet been established, but it is expected to be similar to that of MAP, 1 Hz. No other exchanges between infrastructure and vehicles are required. Figure 11 provides a graphical representation of RLVW. Figure 10 ‐ Graphical Representation of RLVW (source: USDOT) Read the entire page →
From page 86... ... Page 86 RLVW had already been shown to be effective in a multi‐channel environment where Ch. 172 is dedicated to safety, allowing for the necessary bandwidth and interference immunity to be successful. Reducing the spectrum to 30 MHz affects both DSRC and LTE C‐V2X. Moving DSRC from Ch. 172 to Ch. 180 eliminates the guard band currently present between the lower unlicensed bands and Ch. 172. Ch. 180 would be immediately adjacent to the unlicensed UNII‐4 on the lower side, and LTE C‐V2X immediately above, resulting in adjacent channel interference. LTE C‐V2X would be in a similar situation, with DSRC immediately below and unlicensed 6.0 GHz immediately above. Shifting the spectrum could also affect the transmission of the safety‐critical messages. Under the current spectrum alignment, the transmit power allowed for Ch. 180 is 10db lower than Ch. 172, the current safety channel. Lower power will result in a shorter range for message transmission, periodically affecting the ability of a vehicle to receive and react to the data in sufficient time to issue the necessary warnings. For LTE C‐V2X operating in Ch. 183, the transmit power is comparable to that of Ch. 172, likely not creating an impact. Reducing available spectrum also affects channel congestion, for both DSRC and LTE C‐V2X. If a single channel is limited to SPaT, MAP and RTCM only, there may be no issue (Ch. 180 for DSRC and Ch. 183 for LTE C‐V2X) . However, in order to support V2V crash‐imminent safety applications in the licensed spectrum, BSMs will also need to be exchanged on that same channel. The maximum load for a single channel has not been fully examined at scale, but depending on the saturation of vehicles and the quantity of BSMs being exchanged, SPaT, MAP and RTCM have a high probability of being negatively impacted. In the event that PSMs cannot be supported in a 30 MHz environment, there would also be limitations related to alerting a red light violator of a pedestrian in the intersection. Full‐scale testing of multiple applications on a single channel has yet to occur, leaving an unknown depth of the problem. Reduced Speed Zone Warning RSZW is dependent on the timely and continued delivery of accurate speed and road geometry and condition information from infrastructure to the vehicle. Presently, this information is conveyed in the form of the Traveler Information Message (TIM) Read the entire page →
From page 87... ... Page 87 Figure 11 ‐ Graphical Representation of RSZW in a School Zone (source USDOT and SmartColumbus) Potential Impacts Reducing available spectrum, if implemented in freeway applications, absent SPaT and MAP message traffic, it is expected that RSZW would function as designed. However, when co‐located with other applications such as RLVW (i.e. SPaT, MAP, etc.) Read the entire page →
From page 88... ... Page 88 Figure 12 ‐ Graphical Representation of TOSCo (source USDOT) Potential Impacts When compared to the other two priority applications, CA likely has the greatest demand on the system, and is impacted by a reduction in available spectrum. Specifically, a reduced capacity environment will result in limiting exchanges to only safety‐critical messages, requiring advanced vehicle systems to implement alternative communications paths to obtain and share less critical operational, safety and mobility data. Concerns for channel congestion, range, and interference related to the delivery of RLVW and RSZW information apply for CA as well. If the application were able to leverage the proposed unlicensed spectrum, the same issues with single channel approach for safety‐related messages remain, but the unlicensed spectrum at least provides an exploratory option to consider for the additional data needs beyond SPaT, MAP and TIM/RSM, such as CPM and MCM, two messages that are considered unlikely to be deployed in a limited 30 MHz environment but are vital to supporting coordination between automated vehicles. Additional research would be required to determine the feasibility and reliability of making necessary connections to support CA on unlicensed spectrum. Summary of Application Impacts When looking at the system holistically, and beyond the three applications, the less dedicated bandwidth available, the smaller the available set of applications will be that can operate without risk. Eliminating spectrum will limit application support to those using the critical SPaT, MAP and RTCM messages and require devices to use alternative means to support non‐standard message exchange associated with other applications. Absent this ability, it may be difficult for agencies and other deployers to find a benefit cost that is supported. Read the entire page →
From page 89... ... Page 89 Section 5 ‐ Interim Opportunities As noted throughout this white paper, the level of uncertainty surrounding the future of the 5.9 GHz spectrum remains unusually high. The FCC may take further action, the new U.S. DOT administration may increase engagement on the issue, and industry may increase their efforts to satisfy application needs. Even if the FCC publishes the current R&O in the Federal Register as drafted, there remain several possible scenarios where future direction is different than proposed by the FCC. We know from historical perspective that changes in the transportation sector are rarely immediate ‐ whether it is positive or negative, the outcome from this entire reallocation pursuit will not immediately "flip a switch" and change the landscape of V2X. And in particular, when it comes to the IOOs, change is often a slower evolution. In an environment where constrained budgets and frequent policy changes can impact deployment of V2X applications, IOOs would certainly benefit from the stability of regulation and the demand from vehicle manufacturers to help guide their efforts. The authors anticipate that stability will occur in the not‐too‐distant‐future; but even in the absence of that stability, IOOs recognize the opportunity to improve safety and have mitigated the risks to move forward. Advancement Despite Uncertainty During a December 2020 virtual forum, the U.S. DOT acknowledged the current situation but likewise recommended (in general) that projects in motion do not stop.62 They suggested that given the many uncertainties, "it may be unwise to remove operational equipment providing safety benefits." How do agencies go about preparing for additional V2X deployment? Read the entire page →
From page 90... ... Page 90 Pros to this approach include:  Consistent roadside hardware (i.e. signal controllers, network switches, cabinets, poles)  Networked – typically to a TMC  Connected Automation and Red Light Violation Warning are best served by this configuration  Mobility focused – transit signal priority (TSP) Read the entire page →
From page 91... ... Page 91 aid in the prevention or reduction of those incidents must be considered. Further, given varied locations and the potential for varied needs, such as power, communications and mounting, the additional investment required to ensure the availability of these features must also be considered. New Construction When undertaking new construction, the cost for deploying CV technology is at its lowest. However, depending on the reason for construction, the benefits may be longer to realize. Construction driven by safety warrants may have immediate benefits, whereas new construction due to an expanded road network and expected traffic volumes may take longer to realize the payback. In either case, new construction assumes state‐of‐the‐art signal controllers and advanced communications and networking features. In this case, deployment of the actual CV component is minimal. Pros  Modern signal controller and networking  Installation of CV during new construction is at its lowest  Support Red Light Violation Cons  Benefit may take longer to realize  May not be aligned with a corridor or high‐priority location Given the minimal incremental cost of adding CV technology during new construction, it is recommended that agencies include this practice as part of their standard design. Traffic Signal Controller and network hardware should be selected with consideration of CV. Further, if the agency produces a design standard, future integration costs will be at a minimum. Read the entire page →
From page 92... ... Page 92 Conclusions IOOs have been investing in V2X for more than a decade. Some agencies are doing small pilot research projects, while others are engaged in large‐scale deployment efforts. According to recent USDOT statistics, there are more than 139 planned and operational CV deployments and over 20,000 vehicle‐ based devices already in place across 37 states.64 As soon as the FCC's proposal to reallocate the 5.9 GHz spectrum is published in the Federal Register, or if the FCC takes alternative action, the next steps will become clearer. How the industry reacts to the FNPRM, what licensing changes could occur, and what role the new US DOT administration will take remains uncertain. However, given the understanding that IOO projects require time and resources to plan and execute, and any FCC actions won't be immediate, there are efforts to pilot or deploy safety‐ related applications that can continue to be pursued today. Engagement is cited as a best practice by those agencies currently involved in pilot or deployment efforts, and staying up‐to‐date on the FCC's actions is recognized as another. Whether the industry is able to retain the full 75 MHz of dedicated spectrum or must contend with only 30 MHz, there will be needed research, there will be ongoing opportunities, and existing projects will be impacted in some form or fashion. But there are also challenges that can be resolved not by the FCC, but by industry itself ‐ such as the DSRC vs C‐V2X debate, prioritization of message exchange, and application functional requirements and subsequent message needs. As noted previously, additional technical information can be found in the appendices. 64 https://www.transportation.gov/sites/dot.gov/files/2020‐ 06/The%205.9%20GHz%20Safety%20Band%E2%80%94an%20Investment%20in%20America%27s%20Transportati on%20Safety_0.jpg Read the entire page →
From page 93... ... Page 93 Appendix B ‐ Additional Technical Information The background and detailed information in this appendix is intended to provide additional depth to the technical conversation. Technology Definitions It is important to recap certain DSRC and C‐V2X definitions, referring back to the initial white paper:  Current DSRC is based on the 802.11p standard established by IEEE and is designed to operate using 10 MHz channels. The current architecture of most DSRC devices is designed to utilize all seven channels of the 75 MHz band, with specific channels being established for certain safety and control functions.  Future DSRC, called Next Generation DSRC will target using the same 10 MHz channelization scheme, and is being designed to be backward compatible with current DSRC devices using the same spectrum as current devices.  Current C‐V2X is often referred to as LTE C‐V2X because it is based on the current 4G (4th Generation cellular technology) Long Term Evolution (LTE) Read the entire page →
From page 94... ... Page 94 Device manufacturers will require several months, as well as additional funding, to develop and test a FW update prior to releasing it to system operators for deployment. Once device manufacturers provide the new FW, system operators will need to test the update on a few devices to be sure the devices operate as expected, before rolling out the FW to the entire device population. This process can also take several months. Also, System Test Plans, and more specifically Test Cases, will need to be updated to test all DSRC messages on Ch. 180. Additional Test Cases that are developed to test channel congestion impacts could help to understand the new system limitations. If RSUs are connected to a backhaul network, RSU firmware updates can be applied remotely, otherwise a site visit will be required. RSU FW updates can take between 1 and 4 hours depending on the speed of the network connection, the size of the file, and configuration requirements after the update. Theoretically, if OBUs support over‐the‐air (OTA) FW updates, they would be able to receive, download, and apply the updates automatically. It remains unclear, however, how the change in channels for RSUs would still allow OTA connectivity to OBUs ‐ likely requiring hands‐on service. Updating an OBU manually can take between 1 and 2 hours depending on the size of the file and configuration requirements after the update. Figure 14 provides a high‐level overview of the process required to test a FW update and Figure 15 provides a high‐level overview of the process required to rollout a FW update to the entire device population. Read the entire page →
From page 95... ... Page 95 Report and Order limits DSRC to channel 180 Move existing DSRC operations to SCH 180 OBU Manufacturers provide FW update for SCH 180 only operations RSU Manufacturers provide FW update for SCH 180 only operations Update CV Test Plan for SCH 180 only operations Update test RSUs with new FW Test RSUs Firmware update Required Update test OBUs with new FW Test OBUs Test System Figure 13 ‐ Process Required to Test FW Update for Moving DSRC Operations to Ch.180 Read the entire page →
From page 96... ... Page 96 OTA FW is loaded on the OBU firmware update server OBU checks in to the FW Update Server and downloads new FW OBU updates FW Manually Vehicles are recalled to apply FW update Apply FW Update Vehicle is released with new FW Update general OBU population Update general RSU population Remotely On‐Site Log into each RSU from the central location Apply FW update Configure RSU as necessary Configure OBU as necessary Vehicle arrives for update Verify OBU operation Verify RSU operation Drive to RSU location Log into RSU Apply FW update Configure RSU as necessary Verify RSU operation FW Testing is completed Figure 14 ‐ Process Required to Rollout New FW to RSUs and OBUs Read the entire page →
From page 97... ... Page 97 Hardware Swap ‐ DSRC to LTE C‐V2X Radio The second portion of the draft R&O stipulates DSRC systems must migrate to C‐V2X. The migration cannot be accomplished through a firmware update. Instead, it requires a new radio chipset (i.e., a hardware update) . IOOs will need to replace their DSRC devices with C‐V2X devices. The system operator should develop a replacement plan that outlines the steps required to replace devices at intersections and in vehicles, a schedule for when RSUs will be replaced, on a corridor‐by‐ corridor basis, how OBUs will be replaced in each vehicle fleet, how the vehicle owner should schedule for replacement, integration required as devices are replaced, and test cases to be conducted after replacement. The plan should be communicated to relevant stakeholders including the maintenance crew, or 3rd party contractor, that will replace RSUs, the shop(s) Read the entire page →
From page 98... ... Page 98 Report and Order allocates 30 MHz to C‐V2X Move existing DSRC Operations to C‐ V2X Replace DSRC OBUs with C‐V2X OBUs Replace DSRC RSUs with C‐V2X RSUs Update CV Test Plan for C‐V2X operations Test RSUs New HW Required Test OBUs Test system Let RFP/ RFQ Review Proposals\ responses to RFP/RFQ Down select to 2 to 3 device manufacturers Request samples from each Manufacturer Test samples from each Manufacturer Select device(s) based on Test Results Order appropriate quantity, including spares Test sample set of received devices Figure 15 ‐ Replace DSRC hardware Potential for Interference Between Wi‐Fi and V2X Communications As documented in detail in the NCHRP 23‐10 Phase 1 White Paper, numerous testing activities related to spectrum sharing and interference concerns have been conducted by many different organizations, with varying outcomes. As an example, the Alliance for Automotive Innovation (AAI) Read the entire page →
From page 99... ... Page 99 interference from adjacent channels and has engineered the approach to spectrum utilization with those challenges in mind. When originally designed, IEEE 802.11p, and the corresponding WAVE stack of IEEE 1609.x, allowed for a 5 MHz guard band in the first 5 MHz band of the 5.9 GHz spectrum, providing a level of isolation for Ch. 172 from the lower UNII‐4 band. Further, the power level permitted for Ch. 172 is greater than the next Channel, 174, allowing for greater range and noise immunity. On the upper end of the spectrum, Ch. 182 and Ch. 184, a higher power level is also permitted to ensure range and noise immunity for those channels. Channels 182 and 184 were also slotted primarily for public safety sector use, so in effect, served as a guard band on the upper side of the spectrum. The combination of channels, power levels and use of the middle channels 174 thru 180, which apply techniques designed to minimize the interference between these adjacent channels, combine to minimize overall interference. 5GAA, in their initial petition to the FCC understood how DSRC was using the available spectrum and purposefully selected the portion of the spectrum that (in their opinion) was least used when they applied for an experimental waiver. By using a single, 20 MHz channel on Ch. 183, and recognizing that the majority of DSRC messaging lives between Ch. 172 and Ch. 178, C‐V2X and DSRC were effectively afforded a guard band between the two technologies. Given the current draft R&O spectrum reallocation, the FCC needs to examine and remedy interference that will be introduced. This new spectrum allocation, for the most part, has not been tested thoroughly enough to ensure V2X can operate as required to support safety‐of‐life applications. As it stands, further testing is required to truly understand how much Wi‐Fi should limit out‐of‐band emissions to ensure it does not interfere with V2X. If the R&O is put in effect as currently drafted, there is concern among stakeholders that V2X safety‐of‐life applications are at risk of not being able to perform as originally designed. In addition to the ITS‐internal challenges noted, there are other factors which may contribute to unwanted or harmful interference. As was described in the initial white paper and referenced in this one, earlier this year the FCC granted Wireless Internet Service Providers (WISP) Read the entire page →
From page 100... ... Page 100 channelization scheme, specifically channels 172, 174, and 178, or another appropriate channelization scheme This would support the operational needs of the overall ecosystem as well as to help support mobility and other CV‐related services that support the sustainability and viability of the investment. Services such as IPv6 Services (which support certificate top‐off and over‐the‐air updates) , as well as transit priority, lower priority information messages and similar are the prime candidates for operating in the unlicensed spectrum. Operating lower priority CV applications and services in the unlicensed spectrum presents a risk, however, if these services cannot interoperate with other unlicensed services using the same spectrum. In this model, the function of service channels 172, 174, and 176 would continue to operate in the lower 45 MHz, but as unlicensed, along with other unlicensed wireless communications. LTE C‐V2X would continue to operate on channel 183, with NR C‐V2X able to use the unlicensed band to support the enhanced features outlined in the 5GAA deployment roadmap66. Rigorous systems engineering and testing would need to be completed to evaluate this scenario. The key variables for consideration would be channel congestion under heavy load, and adjacent channel or out‐of‐band interference issues. As shown in Error! Read the entire page →

From page 67...

... Page 67 V2X COMMUNICATIONS IN THE 5.9 GHZ SPECTRUM: New Directions, Opportunities, and Challenges Contents Summary ..................................................................................................................................................... 68 Introduction ................................................................................................................................................ 69 Section 1 ‐ The NPRM Process .................................................................................................................... 71 Public Comment Periods (January to May 2020) .................................................................................... 71 Post‐Comment Period Submissions (May to October 2020)