Vehicle-to-everything (V2X) communication – the design engineer’s guide

These days, more and more devices – even simple ones – are becoming ‘connected’, allowing functionality beyond what would normally be possible with their small size. While vehicles have been able to receive information such as radio signals and satellite navigation for some time, few have been truly ‘connected’ and capable of two-way communication.

Automakers are on a mission to enhance the safety, economy and comfort of their vehicles. While recent innovations have made huge strides in this direction, connectivity is seen as the means to take things to the next level.

Termed ‘vehicle to everything’ (V2X), this new sector encompasses vehicle to vehicle (V2V) communication as well as vehicle to infrastructure (V2I) and vehicle to pedestrian (V2P). We have covered V2V in a separate article, so in this technical article we will focus on V2I and V2P.

V2X will use a mesh network approach, with each vehicle being a node on the network, capable of sending and receiving messages as well as relaying them, thereby creating an expansive network where it’s needed most – in highly populated areas.

V2V is a subset of V2X, and refers to the communication of parameters such as speed, direction, location and braking between vehicles. V2I is very similar in many ways, but refers to the communication between a vehicle and the infrastructure around the vehicle. Ultimately, V2X will be an essential part of the fully autonomous vehicles of the (not-too-distant) future.

What is V2X and how does it work?

Figure 1: V2X will integrate a vehicle with its environment, allowing intelligent management of journeys

Many vehicles have some form of advanced driver assistance system (ADAS) that incorporates a multitude of sensors, permitting a range of warnings to the driver and, in an increasing number of cases, semi-autonomous control of the vehicle. The V2X system will become part of the ADAS system and act as an additional sensor, although the inputs will be over-the-air messages. The ADAS system will be able to act upon these inputs in the same way as inputs from a local sensor.

One of the focus areas for ADAS has been vision systems for detecting obstacles in the path of the vehicle. While these systems are now highly sophisticated and able to detect and even identify obstacle types, they cannot see around corners. Fixed hazards, whether permanent such as railway crossings or temporary such as road construction, could be equipped with V2X transmitters meaning that drivers would know about their presence before they could be seen, whether they’re around the corner or hidden by fog.

As well as fulfilling their primary purpose of enhancing safety, V2X systems are also able to enhance comfort and convenience. For example, simple sensors in parking lots can detect empty spaces and direct vehicles towards them via V2X technology.

Economy can benefit from V2X as well – as areas become congested, this information can be passed to the satellite navigation system to allow (or force) the vehicle to navigate around the busy area. Similarly, air quality sensors placed in areas with high levels of pedestrianisation can indicate that air quality has become poor and instruct internal combustion engine vehicles to take a different route.

V2X systems will follow a path of evolution and, in early incarnations, will mostly provide warning signals to the driver. As the technology evolves, it will become more closely coupled to the vehicle’s systems, initially controlling the route via the satnav system and, eventually, taking control of the vehicle movement.

Government involvement

The main involvement of governments and standards bodies has been with regard to the communications protocols. It seemed this was settled when the American National Highway Traffic Safety Administration (NHTSA) selected Dedicated Short Range Communications (DSRC) for V2V. Following backing from the International Standards Organisation (ISO) and lobbying groups, 75MHz of spectrum at 5.9GHz was allocated in 2006. Much later, in 2019, the European Parliament confirmed its backing of DSRC for V2I and V2V.

However, as time has progressed, things have become less clear. The technology industry appears to be favouring C-V2X (cellular V2X) that uses 3GPP mobile radio. The current US administration has not re-ratified DSRC and appears to be letting the market make the final decision. Europe and the Global Automakers trade association (which includes Honda, Nissan, Subaru, Kia and Toyota) continue to officially back DSRC, while Volkswagen has tied its flag firmly to the 5GLTE mast.

Japan has decided on DSRC, but will use the 760MHz band, making its system incompatible with the rest of the world, and the final important market, China, has settled on C-V2X and seems to be pushing ahead in this direction.

Challenges for designers

V2X relies upon a mesh network being created between vehicles and fixed infrastructure to give the necessary coverage without having to deploy (expensive) transmitters specifically dedicated to the system. However, to do this successfully, designers have to overcome a number of challenges:

• With multiple standards and frequencies being proposed for the mesh, producing a global design will be challenging, unless multiple designs are created.
• Addressing the challenges of developing a reliable radio transmitter / receiver for use in the noisy electrical environment of a modern vehicle – especially electric vehicles that have both high voltages and high currents present. The increasing use of mobile devices in vehicles further exacerbates this challenge.
• Ensuring that, although the system has external connectivity, it is safe and secure with regard to malicious interference and / or hacking.

A further challenge lies within the in-vehicle networking (IVN). As data rates increase and the amount of data to be transmitted grows even faster, mainly due to the implementation of multiple vision sensors as part of an ADAS system, achieving the low-latency communications needed within a V2X system requires a new approach.

In general, the automotive industry is settling on Ethernet as the best solution. It is widely-used in commercial, industrial and residential applications which means there’s a good level of understanding of the technology and a large ecosystem of components, software, tools and design resources available, which will speed up the design process and reduce cost.

However, deployment will not be without its challenges, especially ensuring that the implementation is not susceptible to the extensive EMI present in modern vehicles.

The critical role of passive components and connectivity

Figure 2: Block diagram of a modern automotive V2X system

Especially in automotive communication applications such as V2X, passive components have an important role to play. No matter how complex or sophisticated the semiconductors, without EMC components, transient protection, high frequency connectors and antennas, there would be no V2X.

Often, the simplest components can be the most important. Chip ferrite beads are available in 0805 (2.0mm x 0.85mm) packages with rated currents as high as 6A and DC resistance of 9 milliohms. These automotive performance devices allow full current handling up to 85C and their small size allows them to provide EMI protection in even the most densely-populated PCBs.

While audible alerts may be linked into the infotainment system, in some cases a dedicated warning buzzer is needed. Here, miniature piezo speakers can produce sound over a wide frequency range. As the devices cause the surface they are mounted on to vibrate, the sound spreads widely throughout the vehicle, which makes these devices ideal for in-cabin alerts.

Interconnect is vital in any automotive system as designers stack internal PCBs to fit modules into cramped spaces as well as running power, data and RF between modules. High density stacking board-to-board connectors are available with pitches as low as 0.8mm, 16 different stack heights and up to 200 connections. Other types include an in-built all-around EMI shield to minimise EMI within the module where they’re used.

Summary

V2X will bring a whole new level of capabilities to vehicles as they become able to interact with each other, pedestrians and the world around them in smart cities. One major driver for this is to increase road safety by enabling vehicles to communicate their position, speed and direction to each other via a mesh network.

The ability to communicate with smart cities will make journeys shorter, as traffic hotspots can be avoided. The environment will benefit too, as vehicles are operated more efficiently, and if pollution levels rise, vehicles can be diverted from that area.

However, implementing this new technology will hold challenges for designers. As standards have not converged, a single global design is not yet possible and, if they do converge, picking the eventual winner is a design risk. Also, designing a reliable communications system that can perform well within the high noise automotive environment is always a challenge.

Fortunately, as technology permeates the automotive world, a wide range of specifically developed components is available to help solve the design challenges, especially those related to EMI management and interconnection in constrained spaces.

Below we’ve highlighted our leading suppliers for components suited to vehicle-to-everything (V2X) communication.

If you require advice on selecting the right components for your design, our technical specialists are on hand to help.