Hitchhiker's Guide to Hacking Connected Cars: V2X Networks Demystified
"Technological innovation is indeed important to economic growth and the enhancement of human possibilities" -Leon Kass
The idea of vehicles sharing information and working together to make transportation safer, greener, and more enjoyable, is truly compelling. The technologies associated with this concept, collectively known as Cooperative Intelligent Transportation Systems (C-ITS), promise to reduce traffic congestion, lessen the environmental impact of transportation, and significantly reduce the number of lethal traffic accidents. The impact on safety alone makes C-ITS worth considering, since, according to the World Health Organization (WHO), roughly 1.25 million people died in 2015 due to traffic accidents, and with an associated governmental cost of about 3% of GDP.
Intelligent transport system (ITS) technology allows cars to communicate with each other as well as with intelligent traffic infrastructures. The IEEE 802.11p Wireless Access in Vehicular Environments (WAVE) standard allows cars to securely connect to each other as well as to infrastructure, helping to reduce road accidents, saving people’s lives, reducing CO2 emissions and improving traffic flow.
The safety gains created by smarter cars is inarguable as shown in this 70 seconds of safety video from NXP:
Unless you've been an ostrich with your head in the dirt ignoring the transformation happening in the automobile industry over the last 5-10 years, automobiles are becoming more and more connected. According to a Gartner research report published in January of 2015, Gartner expects that by the year 2020, there will be a quarter billion connected vehicles on the road, enabling new in-vehicle services and automated driving capabilities, and that during the next five years, the proportion of new vehicles equipped with this capability will increase dramatically, making connected cars a major element in the ushering in of a new multibillion dollar Internet of Everything economy.
So, how exactly does this all work? Cars talking to cars? Cars talking to roadside equipment? Tomfoolery right? Wrong. Beyond efficiency improvements, it also has the ability to save lives. We'll discuss C-ITS, 802.11p, WAVE, and V2X in further detail in this new chapter of the Hitchhiker's Guide to Hacking Connected Cars series in decomposing V2X networking.
In the last article in this series where I demystified Electronic Control Units (ECUs), I discussed how cars now run over 100 million lines of code, far more than even the F35 Joint Strike Fighter and many modern day cars now contain hundreds of ECUs. Many of these are embedded systems that run embedded operating systems (OSs) such as VXworks, Nvidia Linux, or even Android. The fact is inescapable, cars are now a mesh of different in-vehicle and intra-vehicle computer networks on wheels.
One such type of network is V2X, which stands for Vehicle to Everything communication -- a catch-all term for communication between vehicles (vehicle-to-vehicle or V2V), vehicle-to-infrastructure or V2I, vehicle-to-pedestrian or V2P, and vehicle-to-network or V2N. Examples of V2I can be a connected car sending communication to traffic lights or parking spaces.
But I'll digress on a short detour for just a moment and talk about 5GHz wireless networking. Have you ever been asked the question "why is the signal strength so low on a 5GHz wireless network when someone is using it with their laptop or mobile phone versus the 2.4 GHz network? The reason is that while the 2.4 GHz band offers far greater distance able to better penetrate walls, it's highest throughput speed is 10+ Mbps while the 5GHz band offers far less distance coverage, is less capable of penetrating walls, but offers the highest throughput speed potential of 20+ Mbps. 5GHz wireless networks are actually rarely used in consumer wireless networking. However, this band is leveraged by 802.11p, the IEEE standard in its WAVE or Wireless Access for Vehicular Environments program created for V2X networking. 5GHz is perfectly suited for transporting this data between vehicles because of its high throughput. As a result of its application between vehicles, the short distance limitation is actually not an issue.
Okay, so let's review. V2X is a catch-all for the different ways in which a cyber-physical vehicle (CPV) communicates with roadside equipment or other vehicles or passengers. 802.11p is the protocol used for that communication, which is in the 5.9 GHz range. One thing of particular note right now is a growing battle between two sides of the isle on whether or not the incumbent 802.11[ stays and remains as the de facto standard in V2X networking or if the growing number of technologies and companies supporting C-V2X will replace it. The major differences between the two standards is 802.11p (largely supported by NXP Semiconductor, Marvell, Renesas, and Redpine Signals) must make wireless AD-HOC network sessions to cellular base transceiver stations for GSM connectivity while C-V2X (largely supported by Qualcomm), has two operational modes, one that operates on the 5.9 GHz band and a second mode that operates over the Uu interface for cellular network access. In effect, a C-V2X chipset does not need to rely on AD-HOC networking with cellular base stations for GSM cellular network access.