VIDAS: Visible Light Communications for Advanced Driver Assistance Systems
Key words: Visible Light, White and Colored LEDs, Optical Communications, Wireless Communications
The utilisation of LEDs (light emitting diodes) as illumination and indication devices instead of the current incandescent lamps is supported by a large set of advantages, such as: long time life expectancy, high tolerance to humidity, high power efficiency, minimal heat generation, etc. For these reasons, white and coloured high brightness LEDs are being used, presently, in many applications: indoor illumination, internal and external automobile illumination (rear lights – and now reaching front lights also), control traffic lighting (semaphores), large display panels, etc. These devices have been used to produce large levels of optical power since their main objective is to illuminate large areas or to be visible at long distances. On the other hand, one of the characteristics of an LED device is their ability to switch on or to switch off at high rates. Using LEDs emitting in the visible-light spectrum, both functions, data transmission and illumination (or indication), can be provided simultaneously, opening a set of new interesting scenarios.
VIDAS project will investigate the utilisation of outdoor illumination to increase traffic safety which is an actual important issue. European Union (EU) have set challenging targets for the improvement of road traffic safety by the year 2010. Currently, a list of important Integrated Projects supported by EU, such as AIDE-IP, PREVENT-IP, SAFESPOT-IP, are addressing different ways to improve traffic safety introducing several Advanced Driver Assistance System (ADAS) applications. More, Car-to-Car Communication Consortium is also been working on traffic security improvement based on wireless LANs derived from the standard IEEE 802.11. At the same time, the European Commission (EC) is seeking views of interested parties on its intention to propose measures to foster the rapid introduction of daytime running lights (DRL) for motor vehicles. EC publish a consultation paper titled “Saving lives with DRL” which is opened to comments until 17 November 2006. According to the research available, DRL has a high potential to increase traffic safety. They help road users to better and earlier detect, recognise and identify vehicles. The utilisation of DRL, rear or front lamps of vehicles and the presence of semaphores based on brightness LEDs may extend the ADAS applications increasing traffic safety. The utilisation of wireless communications based on visible-light spectrum for vehicle-to-vehicle and/or semaphores-to-vehicle communications can reduce fatal roadway accidents by providing early warnings to drivers (collision avoidance, speed assistance, intersection support, etc.). While improving road safety, inter vehicle communications and semaphore-to-vehicle communications can also help to optimise traffic flow through an interactive navigation support system.
A large set of the transmission channel properties, in the visible light spectral wavelength range, are similar to the well-known infrared communication channel which have been deeply studied by the VIDAS project team. However, high brightness LED devices, when used in non-directed outdoor applications, present unsolved challenges which will be investigated under this project. VIDAS will perform an extended characterisation of the visible-light optical channel. Based on field measurements, analytical descriptive models will be developed for the main understudy issues of the visible-light channel, which include emitters, receivers and propagation channel. The development of these models will permit the investigation of the best emission and reception techniques as well as the best modulation schemes adjusted to this type of systems.
In spite of VIDAS is mainly oriented for fundamental investigation on a new research area, the feasibility of wireless communications, on outdoor environments, using visible-light spectrum wavelengths will be sustained on experimental optic-electronic transceiver prototypes. The transceiver implementation complexity may require producing ASICs (application specific integrated circuits). During the on going project, some consultants in the areas of vehicle and control traffic lights manufacturers will be listened to compromise the research and development work, delivered under VIDAS project, to practical traffic safety applications.
This project will benefit with the know-how acquired by this project research team in previous investigation in infrared communication systems, funded both at the national and international levels. The main results of this project will include several scientific articles, some post-graduation works, an experimental prototype and the dissemination of the results in academic and industrial communities. The dissemination of the main results should permit to create synergies with several European institutional and industrial partners in future projects.