Phosphor-Free Golden Light LED Array for 5.4-Gbps Visible Light Communication Using MIMO Tomlinson-Harashima Precoding

Visible light communication (VLC) based on light-emitting diodes (LEDs) is supposed as a candidate in 6G networks because it can provide illumination and wireless communication simultaneously. As the widespread use of LEDs, the concern of light pollution and biological safety has arisen. In this paper, we propose a Si-substrate golden light LED array as a new illumination source, using high-efficacy red and yellow LEDs, which has the merits of no phosphor, no blue light, and low color temperature. Based on the golden light LED array and a 2 × 2 PIN array, a 2 × 4 high-speed multiple-input and multiple-output (MIMO) VLC system is demonstrated. Joint MIMO Tomlison-Harashima precoding (THP) scheme is first proposed and conducted for eliminating the combination of inter-symbol interference (ISI) and inter-channel interference (ICI) for carrierless amplitude and phase (CAP) modulation VLC system. Experimental results indicate that MIMO-THP performs well in interference cancellation. The Q factor is improved by 6 dB compared with conventional pure MIMO feedforward equalizer. The overall data rate exceeds 5.4 Gbit/s.