Mitigating end-to-end nonlinearity in LED-based VLC transceivers via an optical intensity feedback

This Letter proposes a novel, to the best of our knowledge, intensity-modulation transmitter equipped with an optical intensity feedback (OIF) loop, which mitigates the holistic nonlinearity on both sides of intensity modulation and direct detection (IM/DD) transceivers from solely the transmitter side. In contrast to the recent effort on pre-distortion, we construct a negative feedback loop bridging the optical intensity of light-emitting diodes (LEDs) toward a sensor for nonlinearity perception to suppress the nonlinearity among all physical devices. In the meantime, we propose an analytical model for the feedback loop and an implementation scheme. The experimental results demonstrate a significant linearity improvement in the total harmonic distortion (THD) and the power gain flatness. More specifically, the average THD of the bipolar junction transistor (BJT)-based OIF transceiver is -49.4 dB (0.37%) and the minimum power gain variance is 0.0005, 0.0025% of the control group. As for the transceiver using a metal-oxide-semiconductor field-effect transistor (MOSFET), its average THD is -52.42 dB (0.25%) and the minimum power gain variance can reach 0.0026. Not only that, since the method only takes advantage of the negative feedback feature and dose not rely on any particular module, it has lower complexity and better applicability.