To make roads safer, improve autonomous driving, and further the aims of the smart city, one particularly important field is vehicular communications, a cooperative communication technology. This technology enables continuous, high-speed, authenticable interactions between moving vehicles. Vehicular communications are typically categorised into four use cases: communications of vehicles to other vehicles (V2V), vehicles to the road-side infrastructure (V2I), vehicles to pedestrians (V2P), and vehicles to the cellular network (V2N). These use cases together are known as vehicles to everything (V2X) and have the potential to significantly change our roads for the better.
Transportation safety is set to improve considerably with the arrival of V2X technology. A report by the U.S. Department of Transportation’s National Highway Traffic Safety Administration says, “If V2X technologies alone are widely deployed, they have the potential to address 81 percent of light-vehicle crashes.” Indeed, V2X technology will provide safety features above and beyond what is offered in other advanced driver assist systems (ADAS) of today. Most of these systems are reliant on computer vision, radar, or lidar technologies. The issue with such technologies is that their signals cannot penetrate through vehicles and no information is available about vehicles that are outside the line of sight. By contrast, V2X provides critical information about vehicles that are both inside and outside the line of sight, provided that they are within a certain communications range. Therefore, V2X makes both semi-autonomous driver-based systems and fully automated systems much more situationally aware. Increased situational awareness means that vehicles can cooperate and reduce accidents in various traffic scenarios.
Automotive V2X technology has a large potential market. According to Juniper Research, the V2X market is anticipated to reach $3 billion by 2022 with a 26% annual rate of growth. It is expected that 50% of new vehicles will have V2V hardware by 2022. Three sectors make up the market:
- Devices/semiconductors: RF transceivers and V2X chipset makers such as Denso, Continental, Delphi, Qualcomm, and Infineon
- Cellular infrastructure: manufacturers (Huawei, Nokia, and Ericsson) and carriers (AT&T, NTT, and Docomo)
- Automobiles: manufacturers such as Toyota and Honda (Japan); GM and Ford (USA); and BMW, Daimler, and Audi (Germany)
For the implementation of V2X technology, two candidate technologies are being put forward: Dedicated Short Range Communications (DSRC) and Cellular Vehicle-to-Any-Device (C-V2X) communications. Both of these are made to operate at the 5.9 GHz band and must adhere to strict reliability and delay requirements:
- Communications latency: Less-than-100-ms delay
- Communications range: At least 300 meters
- Supported vehicular speeds: Typical highway velocities
DSRC is a derivative of WiFi technology. In DSRC, communications protocols (PHY and MAC layers) are specified by the IEEE 802.11p standard. Automotive companies such as Toyota, Honda, and GM are
among the proponents of this technology. The work on DSRC started in 2009, and its communications protocols were fully characterised by 2010. Its supports say that all aspects of DSRC standards from application layer to PHY layer and all safety considerations have been addressed in the last 8 years of development. They believe the technology is ready for deployment on a large scale from 2017. DSRC has known limitations, including support only for the V2V and V2I applications and an upper bound of reliability for vehicle density and communications range.
C-V2X is based on 4G-LTE cellular technology. It is part of the device-to-device (D2D) communications protocol of the sidelink (proximity server) mode of the LTE-Advanced standard. Therefore, it allows every device to detect every other device in its proximity directly. Unlike DSRC, it supports the V2N and V2P vehicular communications use cases. Compared with DRSC, it supports higher speeds (up to 250 Km/h) and higher density (thousands) of vehicles. The proponents of C-V2X technology are a consortium of automotive and wireless device manufacturers known as the 5G Automotive Association (5GAA). These include Intel, Ericsson, Nokia, Audi, BMW, Qualcomm and Denso. According to the 5GAA, the cost of developing a DSRC-based solution is far more than that of solutions based on C-V2X. Moreover, the gap in technology advantages between C-V2X and DRSC will increase after 5G cellular networks are introduced.
So far, neither of these technologies have been selected as the mandated V2X technology in any country. It is likely that both will be adopted; vehicles will be equipped with a smart way to understand and decode data transmitted and received through each of these technologies.
Pain points and solutions
Practitioners of V2X technology include software and hardware developers, integrators and service providers, and testers and performance monitors. The main problems in developing V2X technologies are visualisation, prototyping, and model evolution. Practitioners must be able to achieve the following:
- Visualise, update, and monitor vehicular dynamics and wireless sensor networks (position, velocity, and acceleration of vehicles in network; vehicles entering and exiting the network; RF signal strength at each vehicle; status of links between each vehicle; and other system elements).
- Prototype different collision avoidance and traffic resolution algorithms on V2X chips. This involves wireless modem operations handling transmission and reception of basic safety messages, and also collision avoidance algorithms and traffic control messages that the vehicle processes in real time.
- Evolve their models and monitor the effect of V2X techniques on overall traffic (status of collision avoidance maneuvers, overall communications metrics such as delays and throughput, algorithms to reroute traffic and dynamics of V2X nodes to optimise a given set of criteria) and continuously search for more optimised techniques based on a huge amount of actual field data.
It is critical to ensure that safety-critical applications and devices like V2X work exactly as they were intended. Using computer simulations, we can build a model of the system, its components, and its environment and subject the system to rigorous testing. Model-Based Design tools enable the visualisation, analysis and testing of various traffic scenarios and vehicular dynamics and test that the V2X system provides collision avoidance as expected.
Vehicle electronics of tomorrow
Vehicular transportation and urban safety is transforming radically through automation. Intelligent transportation systems such as autonomous cars are designed to be aware of the events happening around them. These situationally aware systems can respond to movements of other vehicles and pedestrians in real time. With more and more cars on the roads using these types of automated driving features, including V2X, we can significantly improve the safety and security of driving in general. These steps are in the right direction towards reducing automotive collisions. It is indeed an exciting time for vehicle electronics.