Visible Light Communication Image Sensor

LED lighting is more and more omnipresent and its flickering can be modulated to carry data signals. Thus traffic lights, a car's rear- and front-lights, or street lights can be used to broadcast data signals. This is known as visible light communication (VLC). If the modulation is relatively low speed, i.e. the signal has low data capacity, even standard CMOS image sensors can be used to receive these signals. However, for higher bandwidth data, normal CMOS image sensors are insufficient due to their limited frame-rate.

We thus propose to develop a special CMOS image sensor where a single pixel can be addressed and accessed directly without having to read out an entire frame. Thus, one can first read an entire image, then identify the pixels that match a VLC source, and finally access only one of those pixels for high bandwidth signals.

The figure illustrates the process of reading out an entire frame at first, where a street light is identified (by external image processing). Then the pixel corresponding to the center of the light is accessed and can be demodulated to extract the data that i sent through the streetlight. Thus a car can receive local information on traffic, or for example a warning that an emergency vehicle is approaching.

The project shall only concern itself with developing the sensor that has this dual read-out capability and the final aim is to demonstrate communication through the single pixel in the lab and to evaluate how fast this communication can be. A potential limitation here shall be the total capacitance of the read out path for that single pixel and the design will need to investigate ways to minimize it.

Publisert 25. sep. 2017 11:44 - Sist endret 25. sep. 2017 11:44

Omfang (studiepoeng)