A Hybrid Active-Passive Single-Order Equalizer for Visible Light Communication Systems
Xuanbang Chen, Yuhao Wang, Xiaodong Liu, Zhenghai Wang, Xun Zhang, Fuhui Zhou, Derrick Wing Kwan Ng
Abstract
Although visible light communication (VLC) can provide high throughput and low latency, the inherent limited bandwidth of light-emitting diode (LED) remains its performance bottleneck. Thus, an effective equalizer with low complexity and good pervasiveness is indispensable to tackle this issue. In this letter, a hybrid active-passive single-order equalizer is proposed to expand LED bandwidth and support the design of resource-constrained transmitter front-end. Different from other active-passive equalizers, the active part of the proposed method can provide a lower output impedance for equalizer. Then, the effectiveness of the proposed equalizer is verified based on a practical experimental test-bed and it can extend the 3-dB bandwidth of the LED from 9 MHz to 181 MHz even with a trivial transistor. Moreover, the established red-blue-green-yellow (RGBY) LEDs-based VLC system is designed to verify the pervasiveness of the proposed equalizer. In particular, an achievable overall rate of 3.12 Gbps with a transmission distance of 4 m is obtained in the VLC system and the corresponding bit error ratio performance is below <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$1.2\times 10^{-6}$ </tex-math></inline-formula> .