Indoor Positioning System using Light Emitting Diode

Visible light communication (VLC) is a kind of wireless data transmission that delivers data through visible light modulation. Considering this, VLC is used in an indoor positioning system (IPS). This paper explores the concept of VLC in IPS by constructing a hardware system. The proposed system comprises four transmitter circuits with a Bridgelux light-emitting diode modulated to four unique frequencies by 555 timers. A receiver circuit with an STM32F401C discovery board which has an ARM Cortex M4 microcontroller, is connected to an OPT101 photodiode. On the received analogue optical signal, the microcontroller will perform an Analogue-to-Digital Conversion and Fast Fourier Transform (FFT). The FFT's Received Signal Strength (RSS) is fed into a Lambertian optical wireless direct current gain. The distance and position of the photodiode receiver in relation to the LED transmitters are calculated using trilateration technique. Without external ambient illumination, the suggested system can achieve an average location accuracy of 0.2321 m.