Over the past few years, the self-driving car has become a hot topic. Many companies, including Google, believe that this technology can do wonders for global transportation.

Self-driving cars won’t just be convenient; they will also be cheaper, more economical and safer. They can even turn long, boring trips into an opportunity to relax, read a book, or call an appointment.

But tomorrow’s transportation is not just a self-driving car. In future networks The vehicles will work together to ensure the safety of passengers and transport them to their destinations efficiently.

However, for this to happen, cars need a way to communicate with each other.

Ready to talk?

Wireless communication between autonomous vehicles has always been a topic of interest to researchers designing the vehicle of the future. Demonstrations such as a self-propelled car which doesn’t even have a steering wheel, are impressive — but they’re also lonely designs built on a limited scale.

The problem facing researchers is not how create autonomous car, as it has already been done. Instead, the problem is how to make an autonomous car. safe and reliable on modern roads. Autonomous cars working alone can provide convenience to their owners, but they will not be able to fully realize the efficiency, safety and economic benefits that an autonomous vehicle can provide.

These upgrades can only be unlocked through the offline car network. Such a network has not been built, so opinions differ on what it might look like, but researchers are working to bring the idea to fruition.

For example, the Center for Mobility Transformation at MIT aims to make Ann Arbor (the school’s hometown) a leader in automated driving. Larry Burns, a professor of engineering at the school, turned to the animal kingdom for inspiration, noting that:

“The bees are swarming. A flock of geese. And they don’t collide with each other.

A swarm of bugs might seem like an odd comparison to automated cars, but it’s indicative of the tight tolerances that a network of autonomous cars can provide. A typical human driver, with no distractions, takes 215 milliseconds to react. This means that a car traveling at 100 kilometers per hour will travel about six meters (nearly twenty feet) before the driver can even respond. Because of this delay, it is common for safe drivers to leave several cars between them and the car in front of them.

However, radio waves are almost instantaneous (automated vehicles operate at a distance), meaning that automated vehicles could theoretically operate safely with only a few feet between them. Suddenly the image of the swarm makes more sense; the network of autonomous cars will not look like today’s traffic, but like a constant stream of vehicles moving organically, leaving gaps of a meter (and sometimes much less) between each car. At first glance, the movement may seem random, but in fact it will be very coordinated; you would see a stream of cars move to the left, merging into gaps a few centimeters larger than the cars themselves, if there is an exit to the road half a mile away.

But just to say that radio waves will make it possible is like saying «the magician did it!». There are many different concepts for how an automated car network can work, and they generally work in two main categories.

Communication vehicles

The most obvious way to engage networks of automated vehicles. so they can talk to each other directly. From a technical standpoint, it’s relatively simple, and it’s actually a leap from modern collision avoidance technology. Many luxury vehicles now include automated cruise control and low-speed auto-off systems that work using a variety of sensors. Throw in a radio, and a standard through which vehicles can communicate over the radio, and Presto! You have a basic wireless network.

This has an attractive character as it can be used immediately and can be used with vehicles that are not automated. The National Highway Traffic and Safety Administration, America’s leading highway regulator, has already recommended the implementation of vehicle-to-vehicle (V2V) communication for collision avoidance. A report written by four NTSB researchers found that:

“… With the exception of drivers suffering from alcohol or drowsiness, these systems [V2V] deal with 81 percent of all accidents involving drivers without injury.”

This means that V2V systems could prevent most car collisions if all vehicles used them.

A popular theoretical implementation of V2V is the «platoon» system. This idea, which has been around since at least 1993, involves groups of automatic vehicles coming together to form a long, narrow line. This keeps automated cars away from non-automated ones and provides aerodynamic benefits that reduce fuel consumption (with the exception of the lead car).

Almost any type of wireless communication can work in this system, since each vehicle in the platoon will only have to communicate with the one in front of it. Any number of modern wireless technologies (Volvo demonstrated a platoon using 802.11p WiFi) can work reliably, as the short range limits interference and reception problems. Even a short-term loss of communication will not be catastrophic, since each automated machine must match the speed only that was before it. Eric Coiling, engineer at Volvo, told Phys.org that «we [Volvo] believe that taking off can be safer than normal driving today,” and explained that the car manufacturer is carefully studying the most efficient and safest way to implement the idea.

V2V systems like platoon are a relatively easy way to implement autonomous vehicles, but the idea isn’t perfect. All V2V systems do not have centralized equipment responsible for overall transportation. Platoons, for example, are effective for the vehicles involved, but they do not react dynamically to traffic and cannot communicate with road infrastructure. If the platoon encounters heavy traffic, it will simply slow down and take the route determined by the lead vehicle. In V2V networks, there is no way to «see» traffic and calculate an alternative route, or predict the time of the next three stoplights and adjust speed accordingly. The full potential efficiency of an automated vehicle cannot be realized with a larger and more complex system.


This efficiency can only be turned on if it is possible to allow autonomous cars to interact not only with each other, but also with the environment, which allows the use of the “swarm of bees” mentioned earlier. To do this, each car must be able to connect to a network that covers not only its immediate vicinity, but also a much wider area, perhaps as large as the entire city in which the vehicle operates. Such a network is called a vehicle-for-infrastructure, and it is much more complex.

The German company is currently conducting a three-month trial of a V2I system called simTD, which allows connected cars to interact with infrastructure elements. For example, a car with this system can communicate with an upcoming traffic light and adjust its speed to calculate the arrival time with light change. This reduces downtime, which improves fuel efficiency. The system can also alert the vehicle and its occupants of impending road hazards by receiving data when another vehicle skids or experiences a loss of traction.

Even this rudimentary V2I implementation provides security and efficiency, but the downside is complexity. A combination of WiFi, UMTS, and GRPS (the latter two being cellular data standards) are used to ensure constant communication with both infrastructure and other vehicles.

SimTD also uses vehicle-to-vehicle transmissions as a daisy chain to provide infrastructure communications if none of the vehicle’s radios can receive a signal. It’s a great idea, but it means every vehicle in the chain must use a compatible standard, and it’s also a matter of how cellular will be handled by providers of that service.

And then there is the infrastructure. SimTD worked with car manufacturers and the city of Frankfurt for a field trial, but it was limited to only twenty traffic lights. Implementing the infrastructure required for V2I communication will be a costly undertaking and will be particularly difficult (if not impossible) to implement in rural areas where roads are plentiful and there is not much money to build the necessary infrastructure.

Combined solution

All of this makes V2I sound difficult to implement at best, but the good news is that it is fully V2V compatible and can in fact be included in any real system. This means that vehicles that do not have the ability to communicate with the infrastructure can still be networked in a limited sense, and all vehicles can default to V2V communication if needed.

Indeed, we are unlikely to see an infrastructure solution emerge alone anywhere in the world. Building such a network is expensive and time consuming. It also requires mature technology, as changing the communication standard halfway through the building’s infrastructure can ruin the entire project.

V2V platforms, by contrast, have already been deployed in limited numbers. Contrary to what you may have heard, they still have a long way to go before they travel en masse on the highway, but they do exist and can be quickly developed by independent teams.

These two approaches to autonomous vehicles are compatible because they are based on the same communication technologies. In fact, connectivity isn’t the most pressing issue that autonomous vehicles face; SimTD has already demonstrated existing WiFi and cellular may work well. The problem facing researchers is not how they will communicate, but how they should behave once they do.

Image Credit: Wikimedia/SreeBot

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