Some 1,2 million people are killed by car accidents every year and human errors like drunk driving, speeding, ignoring traffic signals and texting while driving are responsible for more than 90% of these fatal accidents. This loss of 1,2 million lives per year is equivalent to seven 500-passenger aircrafts crashing every day.
To reduce the number of car accidents to as close to zero as possible, carmakers, automotive suppliers, governments, academics and even non-automotive technology providers are jointly developing advanced driver assistance systems (ADAS) and ultimately autonomous driving systems.
This new automotive ecosystem is combining a wide variety of advanced technologies such as:
• Sensor fusions with radio detection and ranging (RADAR), light detection and ranging (LIDAR) and optical sensors (cameras).
• High-speed information systems integrating automotive Ethernet networking, powerful signal processing, high definition (HD) mapping with high precision navigation and artificial intelligence (AI).
• Communications for vehicle-to-vehicle (V2V), vehicle-to-network (V2N), vehicle-to-infrastructure (V2I), vehicle-to-pedestrian (V2P), vehicle-to-utility (V2U) and eventually vehicle-to-everything (V2X).
Sensing technologies and artificial intelligence are delivering state-of-the-art 360-degree vision for safe, reliable autonomous driving systems. Similarly, wireless communications will play a critical role in keeping the entire ecosystem of vehicles, infrastructure and pedestrians in sync. These technologies reduce risk by sharing and receiving critical safety information, movements of other vehicles and pedestrians, traffic information and road conditions. This data also helps autonomous vehicles and ADAS systems perform optimally.
Two existing wireless communications technologies, dedicated short range communications (DSRC) and 4G-cellular LTE, are used in current and near-future automotive wireless communications. However, limitations in these technologies affect their suitability for mission-critical requirements for autonomous driving and advanced ADAS systems. Neither provide gigabit/s data rate, high speed mobility support, massive machine communication, or ultra-reliable low latency. In this paper, you will learn how emerging 5G cellular communications solutions address the limitations of DSRC and 4G-cellular LTE to truly deliver on the promise of a safer and enhanced transportation experience.
How wireless communications contribute to autonomous driving
Wireless communication technologies offer three major benefits: safer roads, more efficient traffic routing and more in-vehicle convenience. A wireless-enabled vehicle can share road information and traffic conditions with other cars and/or roadside infrastructure and better anticipate potential risk or delay on the route.
To deliver these benefits, wireless communication technologies use multiple communication methods such as vehicle-to-vehicle (V2V), vehicle-to-network (V2N), vehicle-to-infrastructure (V2I), vehicle-to-pedestrian (V2P), vehicle-to-grid (V2G) and ultimately, vehicle-to-everything (V2X).
Vehicle-to-vehicle (V2V)
Vehicles directly communicate with each other to share pre- and post-collision warnings, near real-time road conditions, blind spot warning and visibility enhancement. V2V also enables connecting two or more vehicles in a convoy, also called platooning.
Here is an example of applied V2V: a leading car passes an icy patch on the road and its anti-lock braking system (ABS) and/or electronic stability control (ESC) system engages. Immediately wireless communications send out warning signals to the following cars so they can slow down or make a detour to avoid this icy road. Another case can be when a leading car is involved in an accident and its airbag system is activated. Immediately wireless signals are sent to following vehicles to reduce their speed or get ready to stop to avoid chain collisions. To properly perform this vital V2V mission, wireless communications need to exhibit very low latency.
Vehicle-to-network (V2N)
Vehicles communicate with a wireless network infrastructure made of base stations and remote radio head (RRH) to share real-time traffic information (e.g. work zone warning). V2N is also used for calling SOS services (e.g. eCall and ERA-GLONASS) and for making remote diagnostics and repair. Unlike V2V, very low latency is not as important, however, reliability is critical. If an eCall or ERA-GLONASS call using V2N fails to connect to emergency services, consequences to persons in need of assistance can be catastrophic.
Vehicle-to-infrastructure (V2I)
Vehicles communicate with roadside infrastructure elements such as traffic signals, road signs, intersections and street lights to share traffic signal change notice, road condition warning, intersection collision warning and pedestrian crossing information. To make such V2I communication seamless, a considerable number of access points must be deployed in the roadside infrastructure, at considerable expense. One of the European car makers launched the first V2I communication pilot program in Las Vegas, USA, in 2016, but more mainstream V2I deployments may take time.
Vehicle-to-pedestrian (V2P)
Vehicles communicate with pedestrians to be warned of a pedestrian crossing or proximity to protect them, even under low visibility conditions such as a dark night, fog, or heavy rain. Mobile devices or wearable devices on pedestrians can be used for V2P communication.
Vehicle-to-grid (V2G)
Vehicles communicate with the power grid to help electric or hybrid vehicles charge during off-peak hours when it is most cost-effective, or to resell stored electricity to the power company by discharging into the grid.
Advantages and limitations of current V2X technologies: DSRC vs. 4G cellular
Before discussing advantages of 5G wireless communications in automotive connectivity, it is worth reviewing the wireless communication technologies currently used in the automotive industry, 802.11p DSRC and LTE-based cellular V2X. Both enable V2X communications but each technology has pros and cons and neither of them can currently enable a full V2X experience.
DSRC is built on the IEEE 802.11p physical layer standard, the 1609 Wireless Access in Vehicular Environment (WAVE) protocol in the US, and the European Telecommunications Standards Institute (ETSI) TC-ITS European standards. The two key benefits of 802.11p DSRC are immediate readiness for the automotive industry and very low latency around 5 milliseconds. Based on proven Wi-Fi 802.11a technology, the IEEE approved the 802.11p specification in 2010. Many car makers who want to deploy their V2X (especially, V2V and V2I) communications right now prefer 802.11p for its availability. DSRC is ad-hoc based communication and doesn’t depend on network infrastructure services.
However, 802.11p requires the installation of many new access points (APs) and gateways, increasing time and cost of full deployment. Since it is based on free Wi-Fi technology, it is difficult to find an operator willing to pay the cost of deploying the APs with no clear business model in sight. There is no clear path for technology evolution either.
Cellular V2X (C-V2X) is more recent to the automotive industry. Recent 3GPP Release 14 defined some C-V2X specifications based on LTE technology (also called LTE-V for vehicles). LTE-V supports automotive wireless communications with networks for V2N as well as device-to-device (D2D) communications for V2V and V2P. A big advantage for C-V2X is that it uses the existing cellular network infrastructures, providing better security, longer communication range and a technology evolution path from 4G to 5G and beyond. However, current LTE-V on 4G LTE networks doesn’t provide the low latency needed to enable critical V2V communications as it varies between 30 ms and 100 ms. If a leading car sends an emergency signal but V2V communications fail to notify following cars in time, a critical situation could develop very rapidly.
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