Communication advances Chapter | 2 25Fig. 2.5 provides an overview of an ITS that relies on VLC for V2V and
V2I communication. The system comprises several infrastructure modules
that connect to the backbone network from various access points (traffic
lights, road signs, etc.) and transmit data to the central office using exist-
ing wired or wireless communication technologies (fiber-to-the-X, ADSL,
etc.). The central office is responsible for the overall information management
and uses the access points to communicate the appropriate information to the
appropriate vehicle (V2I). The V2I and V2V connections are performed using
VLC technology.
LED-based connectivity can be used for:
• Sending messages (downstream) from the traffic lights to the vehicles us-
ing all the three colors of the traffic light (red, green, yellow) to maximize
bandwidth.
• Sending messages (downstream) from road and traffic signs to the vehicles.
Signs have a single-color LED that is used for this purpose.
• Sending information (upstream) from the vehicle to the nearby access points.
The vehicle’s white LED lights can be used for this task. IR LEDs can also
be used during the day.
• Sending data (upstream) from the vehicle
• Exchanging information (upstream/downstream) between nearby vehicles.
The front and rear (e.g., brake) lights of two cars can be used to transfer data
between the vehicles. The use of IR LEDs must also be examined for the
daytime.
The VLC technology can become a sustainable solution for developing
transportation systems, and more specifically “Vehicle Autonomic Management
Systems” (VAMS) since it is reliable, and resilient to any interference and has a
low-infrastructure cost and low-energy footprint.
FIGURE 2.5 VLC as a standard for V2X communications.