Secure Vehicle to Vehicle Communications: Part II - The Wireless Technology Behind It

Posted by William Whyte on October 18, 2011 at 10:07 AM

This is the second of a series of three blog posts about the Connected Vehicle program being run by the US Department of Transportation (USDoT). Last time, I discussed how this program could help save thousands of lives. For this blog, I’d like to focus the on wireless technology. I’ll discuss security considerations in my final blog.

The key to reducing accidents is improving awareness. Broadly speaking, this can be done with sensors or with data communications. A lot of work is being done in the use of sensors. For example, more and more new build cars are incorporating technology such as automated
lane change warnings
(virtual rumble strips) or short-range radar to detect imminent collisions. This helps the car react to imminent collisions by engaging the precrash system to reduce the severity of the crash by tensioning seatbelts, moving headrests, and so on.

These technologies are great, but are better at detecting hazards in the immediate vicinity of the vehicle than distant hazards. But there are other types of accidents that happen at high speeds, are more likely to be fatal, and can’t be predicted by sensors (i.e. if you are coming over a hill at highway speeds and traffic is stopped right in front of you, or you’re going through a green and the driver on the cross street runs the red light). In both those cases, short-range radar and your own eyes aren’t enough to protect you.

The key to awareness is data: information about hazards when they’re known and what cars close to you are doing at all times. Given this collective intelligence, the vehicle can work out if there’s a hazard, and if so, alert the driver. Research has shown that an increase of one second in the reaction time available to a driver can cut the chance of an accident by up to 90%. There’s been research done into the human factors side of this: what types of warning work best, how people react to false positives, and other areas that affect the effectiveness and acceptability of the system.

The basic proposal is that vehicles will be equipped with wireless devices, using 802.11p (a protocol derived from WiFi) for over the air communications at ranges of up to 300 meters. Vehicles can send their location, speed, direction and other information (such as brake light state) using a message known as the Basic Safety Message, specified by the Society for Automotive Engineers (SAE). The communications technology allows these devices to communicate instantaneously, peer to peer, rather than having to go through a cell tower or other infrastructure - and the equipment can be built largely with off-the-shelf components such as GPS and standard WiFi chipsets, which should keep the Bill of Material cost below $100.

So when is this going to happen? Perhaps soon. The standards and technology are mature enough to have been implemented by multiple vendors, and the USDoT is organizing a field trial, known as the Safety Pilot Model Deployment. The goal is to find out how the system works in the real world, and get driver feedback on its effectiveness and ease of use. If this field trial is successful, USDoT will seek a mandate for all new vehicles to have the technology included. Taking into account the time to get congressional approval and the design lifecycles of cars, this means that we could be seeing the system in widespread deployment in 2018.

Once the technology’s available, it doesn’t need to be built directly into cars at manufacturing time. There could be a strong market for aftermarket or retrofitted car safety devices; there could also conceivably be a market for portable or personal devices, especially to protect walkers or cyclists on country roads with poor visibility. Meanwhile, the Europeans are also pushing ahead with plans for almost-identical technology: the European Commission is funding research and standardization work, many countries are running field trials, and the German car manufacturers are considering building the technology into new high-end cars even if there isn’t a mandate.

So this is likely to be real, and it’s likely to happen soon.. In the next post, I’ll start to discuss the security and privacy issues in more detail.

Topics: automotive

William Whyte

Written by William Whyte

William Whyte is responsible for the strategy and research behind the Security Innovation's activities in vehicular communications, security, and cryptographic research. He is chair of the IEEE 1363 Working Group for new standards in public key cryptography and has served as technical editor of two published IEEE standards, IEEE Std 1363.1-2008 and IEEE Std 1609.2-2006, as well as the ASC X9 standard X9.98.