Soft Decision Decoding for Massive Sensor in Visible Light Communication

In this research, we proposed a soft decision de-coding (SDD) using matched filters on the receiving side for Internet of Things (IoT) sensors in visible light communication (VLC). We simulated and analyzed the effect of Matched Filter on the distance between transmitter and receiver in a closed room. The information signal as bits has been modulated using on-off keying Non return to zero (OOK-NRZ) modulation before entering the Light Emitting Diode (LED) lights to be transmitted. The photodiode captured the light and converted it to an electrical signal. We employed SDD to enhance the decoding process from received signals. We consider several parameters to compare performance without a matched filter using a 100 Mbps bit-rate, the number of bits is 1 million bits, and the room size is 3x3x5 m. Also, we evaluated performance using signal-to-noise ratio (SNR) and bit error rate (BER) to compare decoding in the receiver. From the extensive simulation, the results show that maximum receiver coverage is 0.1414 m2 for direct decoding. When the matched filter system is added, we found that the coverage area increases to 0.7697 m2. In addition, SDD using matched filter has an improvement of around 43.5% in terms of coverage, so massive sensors are able to serve optimally.