PERFORMANCE ENHANCEMENT OF WHITE LED BASED VISIBLE LIGHT COMMUNICATION USING BLUE FILTERING AND EQUALIZATION TECHNIQUES

Abstract

This study presents an in-depth experimental investigation into the performance of a white Light Emitting Diode (LED) based Visible Light Communication (VLC) system using blue filtering and equalization techniques. The research focused on analyzing the systems behavior under On-Off Keying Non-Return-to-Zero (OOK-NRZ) modulation at data rates up to 20 Mbps. Simulation and oscilloscope measurements were conducted to examine signal quality parameters such as eye diagram features, Quality Factor (Q-factor), Signal-to-Noise Ratio (SNR), Bit Error Rate (BER), rise/fall time, jitter, and eye height/width across varying temperatures and drive currents (100 mA, 200 mA, 300 mA). The results indicate that increased temperature leads to signal degradation, characterized by reduced Q-factor, eye height, and eye width, and increased jitter, rise/fall times, and BER. The optimal performance was recorded at 200 mA driver current with a Q-factor of 14.250 at 34.80°C. Additionally, blue filtering was applied to enhance the systems modulation response. Spectral and frequency domain analyses revealed that while white light intensity declines sharply with frequency, blue light remains more stable and less attenuated, offering improved bandwidth and reduced signal degradation. Electrical bandwidth was significantly extended using adaptive equalization techniques (Equalization 1 and Equalization 2). EQ2 produced enhanced received signal strength, improved SNR (up to 15.31 dB), and lower BER (as low as 7.22×10⁻³ at 10 MHz). Simulation results using Gaussian-based optical models further validated the optical and electrical efficiency of blue-filtered signals. Furthermore, power consumption analysis revealed that blue LEDs are more power-efficient than white LEDs, particularly at higher frequencies. Overall, the implementation of blue filtering and equalization significantly enhances VLC system performance, enabling more reliable, high-speed optical communication. The findings support the adoption of optimized modulation strategies, thermal management, and spectral filtering in next-generation VLC technologies.