Project: #173 Connected Vehicle Infrastructure for a Smart City Progress Report - Reporting Period Ending: March 30, 2019 Principal Investigator: Jon Peha Status: Overdue Project Start Date: July 1, 2018 End Date: June 30, 2019 Research Type: Advanced Grant Type: Research Grant Program: FAST Act - Mobility National (2016 - 2022) Grant Cycle: 2018 Mobility21 UTC Progress Report (Last Updated: July 17, 2019, 7:42 p.m.) % Project Completed to Date: 50 % Grant Award Expended: 50 % Match Expended & Document: 50 USDOT Requirements Accomplishments The long-term goal of this research is to provide credible and quantitative results that shed light on the most cost-effective strategies for wireless smart city infrastructure to support connected vehicles. The goal until March 2019 is to address major changes in the connected vehicle landscape that have emerged in just the last year or two, including proposed rules for spectrum sharing, cost-effectiveness in the absence of a mandate, and the emerging cellular vehicle-to-everything (C-V2X) technology. During the period ending in March 2019, the major activities performed were threefold. One activity was to modify a detailed quantitative analysis developed earlier in the project and extend it to examine spectrum issues to support connected vehicles. The second major activity was to develop a method to compare competing connected vehicle technologies, i.e. C-V2X and DSRC, and other settings, such as the amount of spectrum and infrastructure, with respect to quality of service for road safety applications. The third activity was to write, publish and present our findings in journal papers and conferences in the areas of transportation and communications, as well as in a Ph.D. dissertation completed during the period. Some of the specific objectives accomplished in this six-month period are on the investigation of spectrum usage by connected vehicles and unlicensed devices, although this work is still in progress. One of these objectives is to assess how much spectrum should be made available for vehicular communications. The U.S Federal Communications Commission (FCC) has allocated 75 MHz of spectrum in 5.9 GHz (the so-called “ITS band”) for DSRC V2V and V2I communications (Lansford, Kenney, and Ecclesine 2013; U.S. Federal Communications Commission 2004). The question of whether all that spectrum should be used exclusively by DSRC devices is hotly debated. For example, it has been proposed that part of the ITS band should be used exclusively by DSRC devices while unlicensed devices are allowed in the other part (Qualcomm 2013). For our analysis, we are considering the scenario in which DSRC-based safety messages are transmitted over spectrum that is not shared for other types of communications, while additional spectrum is used to transmit DSRC-based communications other than safety (i.e., Internet data). The volume of data from mobile Internet has been increasing sharply, and connected vehicles using V2V/V2I links could carry some Internet traffic at a lower cost than macrocellular networks can (Ligo et al. 2017). Therefore, ISPs could reduce cost by taking advantage of roadside units (RSUs) that serve as Internet gateways, rather than deploying cell towers alone. Besides, we considered a base-case scenario where the connected vehicle technology deployed is DSRC. This assumption is consistent with 2016 DOT proposals, although we revisit the technology assumption (see below). We have found that there are realistic scenarios where allocating spectrum far in excess of what is used for safety enhances social welfare, and there are also realistic scenarios where the amount currently allocated is too much. We have analyzed the factors that affect the socially optimal allocation. Some of those factors are uncertain, including the opportunity cost of spectrum in the ITS band. For example, at an OBU penetration of 100% of vehicles and average data rate of incoming traffic of 4 Mbps/vehicle, we have found that it is worth allocating 40 MHz of ITS spectrum, which is the bandwidth currently available for non-safety, as long as the opportunity cost of spectrum is below $0.45 per MHz-pop. However, data rates of Internet traffic in vehicles are also uncertain. For a lower average data rate of 0.4 Mbps per vehicle the same bandwidth could be allocated only if cost is much lower (below $0.05 per MHz-pop). In particular, penetration of OBUs in vehicles is another factor that not only is uncertain, but also depends on whether the U.S. DOT will mandate connected vehicle technology in all vehicles. Out of the context of a mandate, lower penetrations are possible, with OBUs more likely in vehicles that demand higher data rates. We have found that the bandwidth that maximizes social welfare is highly sensitive to penetration. The range of opportunity costs that results in any bandwidth to be allocated is significantly smaller for low penetrations than for the scenarios with 100% penetration. However, we have found that a small increase in penetration (5% to 10%) changes significantly the bandwidths worth allocating. For example, at 10% penetration it is worth allocating 40 MHz (the bandwidth currently available for non-safety) if the cost of spectrum is $0.18/MHz-pop. However, a scenario where it is not worth allocating any spectrum in excess of safety is also plausible for low OBU penetrations or if spectrum costs more than a few tens of cents per MHz-pop. Another specific objective related to spectrum use is to determine whether part of the ITS band allocated exclusively for DSRC devices should be shared with unlicensed devices, such as laptops, tablets and smartphones using Wi-Fi. The FCC issued a Notice of Proposed Rulemaking (NPRM) to permit unlicensed devices in that band (U.S. Federal Communications Commission 2013). However, to date there has been no consensus on whether to share and the rules to be adopted if such sharing is allowed (Lansford et al. 2015). We have found that sharing ITS spectrum with Wi-Fi unlicensed devices is highly efficient. In some realistic scenarios, we have found that vehicles and unlicensed devices using separate bands might require 50-100% more bandwidth than would be required to achieve the same average throughputs in shared spectrum. We have explored several scenarios that indicate that spectrum sharing requires less bandwidth across a representative range of device densities and data rates, and whether unlicensed devices are placed indoors or outdoors. We have also examined sharing strategies based on cooperation, in which unlicensed devices are required to route packets from vehicles to the Internet or other vehicles, rather than merely coexisting with vehicles on shared spectrum. We have found that certain cooperation schemes can be more efficient than simpler coexistence. However, the magnitude of this advantage is scenario-dependent. Given that cooperation would require regulations that are far more complex than coexistence (Peha 2009), it is unlikely that the benefits of cooperation outweigh the cost of implementing it. We have started developing models to evaluate alternative connected vehicle technologies and other network settings with the object to determine with combinations of technologies and settings result in the highest quality of service for certain road safety applications. DSRC is no longer the only technology that one might consider to support short-range communications with connected vehicles and roadside infrastructure. Cellular operators have already been increasing reliance on microcells and femtocells in recent years, but in the past these devices have been problematic for vehicles because handoff times are far too slow for a device that is moving at 50 miles per hour, and end-to-end latency in the cellular network may be too high to satisfy requirements of road safety applications (Lee et al. 2017). More recently, standardization bodies in the cellular industry such as the 3GPP have been advancing a set of standards known as cellular vehicle-to-everything (C-V2X) that includes V2V, V2I, and vehicle-to-base stations. With more options, it is no longer clear whether DSRC, C-V2X, or even some combination of technologies is the best option. Moreover, the cellular technology itself is in flux. For example, unlike DSRC, the initial release of C-V2X is not suitable for high-data-rate users that are explicitly considered in our research, but the latest release may be. For the portions of the standard that are complete, deployment can still take many forms that have yet to be determined. We are investigating some of these issues, and their implications for decisions about connected vehicle infrastructure, as well as connected vehicle spectrum. Many of the findings above are described in a series of research materials. (See Products – Publications.) One of those papers (Ligo and Peha 2018) has reached a broad audience in the wireless communications community. The paper was presented in IEEE DySPAN, which is one of the most important conferences in the world on spectrum issues, both from technical and public policy perspectives, and an extended version is being revised for publication in the IEEE Transactions on Cognitive Communications and Networks journal. Since the audience is not limited to practitioners in the transportation area, we expect to make our work known and receive input from members of communities that are not usually aware of specific issues about connected vehicles. The work resulting from this project has also been published as a Ph.D. dissertation (Ligo 2018) that was completed within the six-month period that this report refers to. Our work has also been disseminated outside the research community. The PI presented our work at a conference about smart cities in the Fall of 2018, hosted by the Allegheny County & Western PA Association of Township Commissioners, which was attended by members of local governments in Western Pennsylvania. We also expect to have our work known to members of the state government, since the Allegheny County & Western PA Association of Township Commissioners lobbies with the Pennsylvania government. Cecchini, Giammarco, Alessandro Bazzi, Barbara M. Masini, and Alberto Zanella. 2017. “LTEV2Vsim: An LTE-V2V Simulator for the Investigation of Resource Allocation for Cooperative Awareness.” 5th IEEE International Conference on Models and Technologies for Intelligent Transportation Systems, MT-ITS 2017 - Proceedings, 80–85. https://doi.org/10.1109/MTITS.2017.8005625. Lansford, Jim, John B. Kenney, and Peter Ecclesine. 2013. “Coexistence of Unlicensed Devices with DSRC Systems in the 5.9 GHz ITS Band.” In 2013 IEEE Vehicular Networking Conference, 9–16. https://doi.org/10.1109/VNC.2013.6737584. Lansford, Jim, John B. Kenney, Peter Ecclesine, Tevfik Yucek, and Paul Spaanderman. 2015. “Final Report of DSRC Coexistence Tiger Team.” Lee, Kwonjong, Joonki Kim, Yosub Park, Hanho Wang, and Daesik Hong. 2017. “Latency of Cellular-Based V2X: Perspectives on TTI-Proportional Latency and TTI-Independent Latency.” IEEE Access 5: 15800–809. https://doi.org/10.1109/ACCESS.2017.2731777. Ligo, Alexandre K. 2018. “Connected Vehicles for Internet Access: Deployment and Spectrum Policies.” Carnegie Mellon Univesity / University of Porto. https://kilthub.cmu.edu/ndownloader/files/13710707. Ligo, Alexandre K., and Jon M. Peha. 2018. “Spectrum for Intelligent Transportation Systems: Allocation and Sharing.” In IEEE International Symposium on Dynamic Spectrum Access Networks, DySPAN. Ligo, Alexandre K., Jon M. Peha, Pedro Ferreira, and João Barros. 2017. “Throughput and Economics of DSRC-Based Internet of Vehicles.” IEEE Access 6: 7276–90. https://doi.org/10.1109/ACCESS.2017.2785499. Peha, Jon M. 2009. “Sharing Spectrum through Spectrum Policy Reform and Cognitive Radio.” Proceedings of the IEEE. 2009. https://doi.org/10.1109/JPROC.2009.2013033. Qualcomm. 2013. “Comments of Qualcomm Incorporated.” ET Docket No. 13-49. http://apps.fcc.gov/ecfs/document/view?id=7022418821. U.S. Federal Communications Commission. 2004. “Report And Order 03-324.” ———. 2010. Connecting America: The National Broadband Plan. USA. https://doi.org/10.1002/yd.20038. ———. 2013. “Revision of Part 15 of the Commission’s Rules to Permit Unlicensed National Information Infrastructure (U-NII) Devices in the 5 GHz Band. Notice of Proposed Rulemaking 13-22 (Docket 13-49).” https://apps.fcc.gov/edocs_public/attachmatch/FCC-13-22A1.pdf. Impacts Due to its interdisciplinary nature, the project has had impact in the body of knowledge in the areas of transportation, wireless communications and Internet policy. Our work is able to inform both technical and policy decisions regarding the deployment of connected vehicle infrastructure, spectrum and technology. This work has been presented to policymakers, including individual meetings with leaders in the City of Pittsburgh and the U.S. Federal Communications Commission, and conferences targeted at policymakers in state and local government. In the federal level, our research has impact on the current debate about the use of spectrum for Intelligent Transportation Systems. While it has been recently proposed that spectrum is shared between vehicular and unlicensed devices, transportation authorities have concerns that such sharing may cause harmful interference to vehicular communications. Our research so far concludes that as long as safety messages are transmitted on exclusive spectrum, policymakers in the federal level could allow vehicles and unlicensed devices to share spectrum for non-safety communications in a highly efficient way. Our work is focused on the capability of DSRC technology to carry Internet data from fast-moving users such as those in vehicles. We are able to uniquely inform decisions about wireless communications and Internet policy that involves the use of ITS spectrum. The policy decisions that our work is able to inform may have societal implications related to Internet access. Decisions leading to a more efficient use of connected vehicle spectrum may result in more users being allowed in that spectrum for Internet access purposes. The societal benefits of adding spectrum for Internet access has been discussed in work such as the National Broadband Plan (U.S. Federal Communications Commission 2010) and others. Those benefits include increase in social welfare, innovation leading to enhanced competitiveness, support broadband deployment in high-cost areas or for low-income Americans, and maximize benefits of broadband in public education, health care and other sectors. We are currently conducting novel research that will have impact on policies beyond Internet access, More specifically, this new work is related to the types of infrastructures that municipal governments should deploy, which includes impact on road safety. The potential of connected vehicle applications to enhance road safety depends on their quality of service (QoS). QoS measures of applications should indicate how timely and reliably threats are detected and are communicated to drivers or autonomous systems such that those threats can be avoided or the impact mitigated. The QoS of road safety applications is affected by design choices that include how much spectrum to allocate, spectrum usage rules, what communications technology (such as DSRC or C-V2X) to deploy in vehicles and infrastructure, what type of infrastructure to deploy (e.g. small cells or macrocellular towers), at what locations, and what communications capacity is needed at each location. QoS of applications also depend depends on the level of utilization of V2X devices and spectrum in a given location and time. However, there are open research questions related to QoS of applications. One is what the most appropriate QoS measures that can be used to compare design choices are. Another question is what the relationship between the QoS of applications and the communications performance of the design choices is. For example, it is unclear whether differences in packet loss or latency between DSRC and C-V2X translates into differences in crashes avoided. We are currently developing simulation and analytical models which impact will be on informing what design choices are the most effective for road safety. In addition, during this report period the project has enabled the direct development of human resources. The funding from this project helped a PhD student who is a member of a underrepresented group (Hispanic) complete his dissertation work. His dissertation includes all the contributions described above, and the knowledge acquired in the project allows him to work in the areas of transportation, communications, or both. It has also given opportunities to an undergraduate student to perform research. In addition, as a result of this research, two educational modules have been developed. One has been used in a course on Policies of Wireless Systems, and the other has been used in a course on Internet Policy, both taught by the PI at Carnegie Mellon University. Other Earlier in this project we developed the modeling approach which description is published in the IEEE Access journal paper. For this report period, we extended both the simulation software and the engineering-economic models to address spectrum-related issues. The simulation software was extended to allow us to vary the amount of spectrum allocated for DSRC-equipped vehicles and RSUs, and then observe the data throughput resulting from each amount of spectrum. (The relation between data throughput and other factors such as densities of DSRC-equipped vehicles, RSUs, and data rates has already been examined earlier in the project.) The simulation was also updated to allow the estimation of throughputs to both vehicles and unlicensed devices, either when those devices used shared spectrum or separate bands. The engineering-economic models were updated to allow us to estimate the optimal amount of spectrum to allocate for ITS, as a function of the opportunity cost per unit of that spectrum. Compared to preliminary deliverables produced earlier in the project, in this six-month period we completed and extended our work on spectrum by incorporating scenarios that represent the relevant range of population densities, device penetrations and data rates expected in the U.S. for the next five years. We are currently extending the engineering-economic approach to compare design choices for road safety applications. Those design choices include the emerging C-V2X or DSRC technologies. The approach is based on the simulation models developed in (Cecchini et al. 2017), which we are extending in order to measure application-level QoS measures. Outcomes New Partners none Issues none