Adaptive digital predistortion implemented by FPGA and soft microprocessor core

Orthogonal frequency division multiplexing (OFDM) is an effective approach to enhance transmission data rate of the visible light communication (VLC) using a light emitting diode (LED) as the transmitter. However, the inherent nonlinearity of LEDs transmitter imposes performance limitations to the VLC systems. The nonlinearity of LEDs could be changed depending on the conditions of temperature variation, device aging and so on. In this paper, we realized an OFDM VLC system based on field-programmable-gate-array (FPGA) and its Soft Microprocessor Core. And in this system, the LED nonlinearity is compensated by the predistortion technique, which could greatly improve the performance of the VLC system.