Designing Embedded Visible Light Communication System Adaptable to Fluctuations in Light Intensity

Internet of Things (IoT) extends the connectivity of internet connected devices like laptops, smartphones with internet-enabled embedded devices using wireless communication technology and sensing devices to interact with the external world. IoT based devices mainly use wireless technology like WiFi, Zigbee, Bluetooth Low Energy (BLE) for communication. Due to the large number of IoT devices and limited spectrum in the Radio Frequency band the system suffers from bandwidth crunch. Hence, the high bandwidth capacity of visible light provides the solution to the spectral crisis. So, the visible light based new wireless technology opens up a new domain of integrated communication system with sensors using lights. The LED beams transmit information from the transmitter's side to the photo-detector on the receiver's side. But, the photo-detector is affected by fluctuations in the brightness of ambient light and also by the variations in the distance between transmitter and receiver. To solve these problems, we design a hardware circuit to eliminate the effect of ambient light during transmission and also remove the effect of the variable intensity of transmitted LED power introduced due to change in the relative distance between the transmitter and receiver. In the experimental setup we use 5mm RED LED and OPT101 photodiode as transmitter and receiver respectively. Our experimental setup can eliminate up to 273 lux ambient light and detect bits correctly upto a bit duration of 1 μs