Cellular V2X as the Essential Enabler of Superior Global Connected Transportation Services
By Apostolos (Tolis) Papathanassiou and Alexey Khoryaev, Next Generation and Standards, Intel Client and Internet of Things Businesses and Systems Architecture Group (CISA), Intel Corporation
IEEE 5G Tech Focus: Volume 1, Number 2, June 2017
Vehicular-to-Everything (V2X) communication is essential in enabling safe, reliable and efficient transportation services which can be deployed both near- and long-term and can meet the vehicular use case requirements of today and tomorrow. This paper shows through analysis and simulation that Cellular V2X (C-V2X) – the technology developed within the 3rd Generation Partnership Project (3GPP) and designed to operate in both vehicle-to-vehicle and vehicle-to-network modes – is the prominent technology that can achieve the V2X requirements and pave in the most efficient manner the way to connected and automated driving.
Vehicle-to-everything (V2X) communication is essential in providing real-time and highly reliable information flows to enable safe, efficient and environmentally-conscious transportation services and paving the way to connected and automated driving (CAD). Cellular V2X (C-V2X) is the technology developed in 3GPP1 and is designed to operate in two modes :
- Device-to-device: This is Vehicle-to-Vehicle (V2V), Vehicle-to-(Roadway) Infrastructure (V2I) and Vehicle-to-Pedestrian (V2P) direct communication without necessarily relying on network involvement for scheduling.
- Device-to-network: This is Vehicle-to-Network (V2N) communication which uses the traditional cellular links to enable cloud services to be part of the end-to-end solution by means of network slicing architecture for vertical industries.
Since V2X must be deployed in the near term and should be extended to the future, it must offer the necessary high performance to meet use cases of today , e.g., intersection movement assist, emergency electronic brake light, forward collision warning, blind spot warning, lane change warning, etc., while being future proof and scalable to meet the requirements of use cases of tomorrow, e.g., Advanced Driver Assistance Systems (ADAS), where vehicles can cooperate, coordinate and share sensed information, and ultimately CAD.
2. C-V2X performance advantage for V2V communications
Based on the recently completed 3GPP Release 14 specification, C-V2X offers superior performance over IEEE 802.11p – an amendment to the IEEE 802.11 standard defining enhancements to support Intelligent Transportation Systems (ITS) applications, also referred to as DSRC (Dedicated Short-Range Communications) from the related project of the US Department of Transportation which considered IEEE 802.11p – with respect to coverage, mobility support, delay, reliability and scalability, which makes C-V2X the most suitable candidate in the 5.9 GHz ITS spectrum to meet the near-term vehicular communication requirements. As an example of the benefits of C-V2V (LTE V2V) with respect to coverage, Figure 1 presents the average Packet Reception Ratio (PRR) versus distance for the Freeway (70 km/h) and Urban (15 km/h) scenarios of the 3GPP LTE V2V evaluation methodology . The following two system configurations for the LTE V2V were evaluated: 2.16 MHz bandwidth (12 PRBs or 144 subcarriers) with 1 TTI (Transmit Time Interval) of 1 ms and 1.08 MHz bandwidth (6 PRBs or 72 subcarriers) with 2 TTIs of 1 ms each. The bandwidth for DSRC is 10 MHz, the FFT (Fast Fourier Transformation) size is 64 points and the symbol equals 8 us (6.4 us useful symbol duration and 1.6 us cyclic prefix duration). For all deployment scenarios (DSRC, LTE V2V with 6 PRBs and LTE V2V with 12 PRBs), the payload size is equal to 1544 bits and the modulation scheme is QPSK. As it can be seen from Figure 1, LTE V2V has superior coverage compared to DSRC with the improvement of the covered distance at an average PRR of 90% ranging from 33% (LTE V2V with 6 PRBs) to 58% (LTE V2V with 12 PRBs) for the Freeway scenario and from 18% (LTE V2V with 6 PRBs) to 41% (LTE V2V with 12 PRBs) for the Urban scenario of the LTE V2V evaluation methodology .
Similar coverage advantages of LTE V2V against DSRC (IEEE 802.11p) are presented in ,  and  using the same evaluation metric, i.e., the average PRR versus distance, and similar evaluation methodologies. Table 1 summarizes the range improvement of LTE V2V vs. DSRC based on the evaluation results of ,  and , which correlate favorably with the range improvement based on the results presented in Figure 1.
In addition to its performance advantages, C-V2X – as part of the 3GPP standards family – offers an evolution path to 5G which will enhance the 3GPP Release 14 specification through its highly reliable and low-latency mission critical service design for V2X applications and, thus, will provide the required technology roadmap for enabling ADAS and CAD. Finally, it is important to note that C-V2X can leverage well-designed and tested upper layer specifications from ETSI, ISO, SAE and IEEE. In this way, the latest 3GPP specified PHY and MAC can be used together with legacy C-ITS specifications to enable the best possible V2X deployments in the 5.9 GHz spectrum as early as 2018.
3. C-V2X access to global spectrum
Since C-V2X can offer both device-to-device (V2V, V2I and V2P) and device-to-network (V2N) services which will transform connected transportation around the globe, it is important to consider the spectrum that needs to be utilized for that purpose. As the 5.9 GHz ITS spectrum is clearly emerging as the primary common global spectrum to be used for basic safety applications around the world, it is of major importance that the use of C-V2X direct communication in 5.9 GHz is secured in order to guarantee that the superior C-V2X technology advantages can be used both near- and long-term for the public good. In this way, C-V2X services will not only find their way to the market and the public through the use of the 5.9 GHz ITS spectrum, but they will also motivate the use of commercial cellular bands for additional non-ITS V2X use cases to complement the safety services predominantly provided in the 5.9 GHz ITS spectrum. It is noted that 5.9 GHz is not ideal for infrastructure deployment as the relatively high frequency renders coverage more challenging than typical cellular bands at or below 2 GHz. In C-V2X, however, direct communications on 5.9 GHz will be combined with WAN (Wireless Area Network) communications offered for either coverage or capacity on any other LTE band and eventually in 5G bands. It is also worth noting that millimeter wave bands in 5G can be used for high volume data transfer – due to their dramatically higher spectrum size than spectrum below 6 GHz – while also providing low latency WAN support for ADAS and CAD. Finally, coexistence of different technologies in the same 5.9 GHz ITS band, using such schemes as different channel assignments, are under study in 3GPP Release 14 and other standards fora. Such studies have merit as it is best policy to provide sufficient harmonized spectrum for the best low latency V2V communication technology in order to save lives and usher a future of connected and automated driving.
It is important to mention the ongoing work in ITU-R Working Party 5A to further develop spectrum requirements and spectrum studies at the national, regional and global level that will support existing and future use cases envisaged for road safety and traffic efficiency applications. These applications will require spectrum beyond the currently harmonized 5.875-5.905 GHz, comprising at least the 5.905-5.925 GHz band. It is also worth noting that a group of leading companies from the automotive and telecommunication industries formed the 5G Automotive Association (5GAA) in September 2016  in order to accelerate the development and deployment of C-V2X technology around the globe. We believe that the 5GAA ecosystem will assist the effort required to appropriately allocate the ITS spectrum at 5.9 GHz for the uptake of innovative ITS solutions and business models in the years to come, while it will contribute to the definition of next-generation vehicular communications towards connected and automated driving.
Summarizing, C-V2X is expected to be instrumental in transforming connected transportation services throughout the globe. C-V2X direct communications can operate both in ITS spectrum and in commercial cellular spectrum, combined with network-based C-V2X communications operating on existing and future cellular networks. The newly formed 5GAA is a clear proof of the existence of a strong ecosystem of leading automotive and telecommunication companies which is confident that a technically superior standards-based, cost-effective and scalable access technology from the cellular industry will carry C-ITS and Connected Vehicle applications well into the 5G era and beyond.
- The 3rd Generation Partnership Project (3GPP) unites seven global telecommunications standard development organizations and covers cellular telecommunications network technologies, including radio access, the core transport network, and service capabilities and thus provides complete system specifications.
- 5G Automotive Association, “The case for cellular V2X for safety and cooperative driving”, White Paper, November 2016, URL: http://5gaa.org/pdfs/5GAA-whitepaper-23-Nov-2016.pdf.
- SAE International, J2945/1, On-board system requirements for V2V safety communications, March 2016.
- 3GPP TR 36.885, Study on LTE-based V2X Services (Release 14), 3GPP Technical Specification Group Radio Access Network, v14.0.0, June 2016.
- Blasco et. al, “3GPP LTE enhancements for V2V and comparison to IEEE 802.11p”, 11th ITS European Congress, Glasgow, Scotland, June 2016.
- R1-163032, “Details of sensing for V2V”, Qualcomm Incorporated, 3GPP TSG-RAN WG1 #84bis, Busan, South Korea, April 2016.
- R1-161132, “V2V system level performance”, Qualcomm Incorporated, 3GPP TSG-RAN WG1 #84, St. Julian’s, Malta, February 2016.
- 5G Automotive Association, URL: http://5gaa.org
Apostolos (Tolis) Papathanassiou is a Senior Principal Engineer with the Next Generation and Standards (NGS) organization of the Intel Client and Internet of Things Businesses and Systems Architecture Group (CISA). He is responsible for LTE PHY and MAC standardization and has been leading different 5G technology development and standardization activities. He has more than 50 scientific contributions to international journals, conferences, and books since 1994, more than 20 awarded patents/patent applications in 3G (TDSCDMA and WCDMA), 4G (WiMAX, LTE), satellite (LEO/MEO), and Wi-Fi (IEEE 802.11a/g/n) wireless communications systems since 1996, and more than 100 contributions to wireless standardization bodies such as 3GPP, IEEE 802.11, IEEE 802.16, and WiMAX Forum since 1999. Previously at Intel, he led multiple standardization efforts in ITU-R and IEEE 802.16/WiMAX Forum. Before joining Intel, Apostolos worked on multiple-antenna PHY techniques and algorithms for 3G, satellite, and Wi-Fi wireless systems.
Alexey Khoryaev was born in Dzerzhinsk in 1980. He received his M.Sc. from the Radiophysics Faculty of the Nizhny Novgorod State University, Russia, in 2002. Since 2003, Alexey has been working as a senior research scientist in the wireless standards and technology group of Intel Nizhny Novgorod Lab. His research interests are in the areas of digital signal processing and physical layer design for communication systems. In his career, Alexey has been actively contributing to different standard associations developing wireless communication systems. Since 2011, on behalf of Intel Corporation, Alexey serves as a 3GPP RAN1 WG delegate developing physical layer technology for cellular communication systems. Last years his main focus was on the 3GPP LTE sidelink design used for proximity services and vehicular communications.
Editor: Stefano Buzzi
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