The automotive industry has always been a keen user of wireless technology. In the early 1980s, Renault made it possible to lock and unlock the doors on its Fuego model utilizing a radio transmitter. Within a decade, other vehicle manufacturers embraced the idea of remote key-less entry and not long after that it became a standard feature. Now, wireless technology is about to reshape the world of driving.
The first key-less entry systems were based on infra-red (IR) signals, borrowing the technique from automatic garage door openers. But the industry swiftly moved to RF technology, in order to make it easier to use. Although each manufacturer favored its own protocol and coding system, they adopted standard low-power RF frequency bands, such as 315 MHz in the US and 433 MHz in Europe. As concerns about theft emerged, they incorporated encryption and other security features to fend off potential attacks. They have further refreshed this technology as new threats appeared, as well as adding features such as proximity detection to remove the need to even press the key-fob remote's button.
The next stage in favor of convenience was to employ Bluetooth instead of custom radios on the sub-1GHz frequency band so as to dispense with the keyfob altogether. With Bluetooth, an app on the user's smartphone can not only unlock the car doors, but also handle tasks such as starting the heater or air-conditioning to make the vehicle comfortable ready for when the driver and passengers actually get in.
Bluetooth itself has become a key feature on many models over the past decade as automobile manufacturers have looked to open up their infotainment systems. Access to the functions located on dashboard through Bluetooth has made it possible for vehicle occupants to hook up their phone handsets easily. Initially, it was to support legal phone calls through hands-free operation without forcing the owner to buy and install a permanent phone in the vehicle itself. But the wireless connection is just as good at relaying high-quality audio so that the passengers can listen to their favorite music (stored on portable devices). We have clearly move a long way from the CD auto-changer located in the trunk. Bluetooth is a prime example of the way in which RF technology, once in place, can support many different applications - with plenty of potential for use cases that have not yet been considered. Through use of a suitable relay device in the car, Bluetooth also provides the means by which to send vehicle diagnostics information to relevant smartphone apps. The use of the technology for diagnostics gateway points to an emerging use for Bluetooth in improving the overall safety of car transportation.
But now Wi-Fi is also primed to become as ubiquitous in vehicles as Bluetooth. Wi-Fi is able to provide a more robust data pipe, thus enabling even richer applications and a tighter integration with smartphone handsets. One use case that seems destined to change the cockpit experience for users is the emergence of screen projection technologies. Through the introduction of such mechanisms it will be possible to create a seamless transition for drivers from their smartphones to their cars. This will not necessarily even need to be their own car, it could be any car that they may rent from anywhere in the world.
One of the key enabling technologies for self-driving vehicles is communication. This can encompass vehicle-to-vehicle (V2V) links, vehicle-to-infrastructure (V2I) messages and, through technologies such as Bluetooth and Wi-Fi, vehicle-to-anything (V2X).
V2V provides the ability for vehicles on the road to signal their intentions to others and warn of hazards ahead. If a pothole opens up or cars have to break suddenly to avoid an obstacle, they can send out wireless messages to nearby vehicles to let them know about the situation. Those other vehicles can then slow down or change lane accordingly.
The key enabling technology for V2V is a form of the IEEE 802.11 Wi-Fi protocol, re-engineered for much lower latency and better reliability. IEEE 802.11p Wireless Access in Vehicular Environments (WAVE) operates in the 5.9 GHz region of the RF spectrum, and is capable of supporting data rates of up to 27 Mbit/s. One of the key additions for transportation is scheduling feature that let vehicles share access to wireless channels based on time. Each vehicle uses the Coordinated Universal Time (UTC) reading, usually provided by the GPS receiver, to help ensure all nearby transceivers are synchronised to the same schedule.
A key challenge for any transceiver is the Doppler Effect. On a freeway, the relative velocity of an approaching transmitter can exceed 150 mph. Such a transmitter may be in range for only a few seconds at most, making ultra-low latency crucial. But, with the underlying RF technology for V2V in place, advanced navigation applications can be deployed relatively easily and extended to deal with many other objects and even people.
V2I transactions make it possible for roadside controllers to update vehicles on their status. Traffic signals, for example, can let vehicles know when they are likely to change state. Vehicles leaving the junction can relay that data to approaching cars, which may slow down in response. By slowing down, they avoid the need to stop at a red signal - and thereby cross just as it is turning to green. The overall effect is a significant saving in fuel, as well as less wear and tear on the brakes. In the future, such wireless-enabled signals will make it possible improve the flow of autonomous vehicles considerably. The traffic signals will monitor the junction to check whether conditions are safe and usher the autonomous vehicle through to the other side, while other road users without the same level of computer control are held at a stop.
Although many V2X applications were conceived for use with a dedicated RF protocol, such as WAVE for example, there is a place for Bluetooth and, potentially, other wireless standards like conventional Wi-Fi. Pedestrians and cyclists may signal their presence on the road with the help of their own Bluetooth devices. The messages picked up by passing vehicles can be relayed using V2V communications over WAVE to extend the range of the warnings. Roadside beacons using Bluetooth technology can pass on information about local points of interest - and this can be provide to passengers who can subsequently look up more details on the Internet using the vehicle's built-in Wi-Fi hotspot.
One thing seems to be clear, the world of automotive design will be a heterogeneous RF environment that takes traditional Wi-Fi technology and brings it together with WAVE, Bluetooth and GPS. It clearly makes sense to incorporate the right set of radios together onto one single chipset, which will thereby ease the integration process, and also ensure optimal performance is achieved. This will not only be beneficial in terms of the design of new vehicles, but will also facilitate the introduction of aftermarket V2X modules. In this way, existing cars will be able to participate in the emerging information-rich superhighway.