A Real-Time RGB PAM-4 Visible Light Communication System Based on a Transceiver Design with Pre- and Post-equalizations

Jian Kang, Xuanzheng Wang, Li Wang, Can Wang, C. Patrick Yue

Abstract: VLC is becoming a trending of next-generation communication because of its broad-spectrum range and unique application scenario. The transmission speed is limited because of the LED bandwidth. Equalization technology on analog frontend or digital baseband can broad the bandwidth of the whole system. High order modulation scheme is also an effect way to improve the data rate under a fixed bandwidth. This work presents a novel RGB PAM-4 transceiver employing digitally controlled asymmetric FFE and cascaded CTLE. The PAM-4 signal with one-tap FFE is composed of six OOK signals with different delays in the optical domain. Delay control is implemented in digital baseband and no DAC is needed in the system. The transceiver achieves 250% increase in bandwidth extension ratio in VLC links using ordinary RGB LEDs by allowing independent PAM-4 eye-height tuning.