A Gb/s VLC Transmission Using Hardware Preequalization Circuit

In this letter, we proposed a constant-resistance symmetrical bridged-T amplitude equalizer for high-speed visible light communication (VLC) system. Using the hardware equalizer, we successfully demonstrated a gigabit per second VLC transmission over 80-cm free space based on a RGB LED. The measured bit error rates (BERs) for the signals in 64-quadratic-amplitude modulation (64QAM) single carrier modulation at 1.05-Gb/s, 64QAM-orthogonal frequency division multiplexing (OFDM) at 1.05 Gb/s, and bit and power loading OFDM modulation at 1.42 Gb/s, are under 7% pre-forward error correction (pre-FEC) limit of 3.8 × 10^-3, clearly validating the feasibility of the proposed equalizer. Compared with the system without using the equalizer, the BER performance of the VLC systems can be improved at least by 1 order of magnitude. Moreover, the equalizer can be easily integrated into amplifier or LED because of its compact size and easy installation for just using passive component. To the best of our knowledge, it is the highest data rate with longest transmission distance using preequalization circuit.