Bandwidth enhancement with DAC-enabled pre-equalization and real-valued precoding for a FBMC-VLC

Abstract

Modulation bandwidth limitation is one of the major drawbacks in light-emitting diode (LED)-based visible light communication (VLC) systems. Various advanced physical-layer modulation formats with digital/analog pre-equalization or adaptive modulation techniques are usually employed to improve the transmission rate of VLC systems. In this Letter, we use a radio frequency (RF) digital-to-analog converter (DAC) to directly realize signal pre-equalization without additional digital or analog signal processing. In addition, low-complexity real-valued precoding techniques are applied to reduce the peak-to-average power ratio (PAPR) and equalize the subcarrier signal-to-noise ratio (SNR). The proposed hybrid scheme is experimentally investigated in a spectral-efficient filter bank multi-carrier (FBMC)-based VLC transmission system. The results exhibit that the PAPR can be reduced by more than 3 dB at the complementary cumulative distribution function of 1 × 10−4 with the real-valued precoding techniques. By using the proposed hybrid scheme, the modulation bandwidth can be increased to 515 MHz for 16QAM-FBMC with a bit error rate below 3.8 × 10−3 after 2.3-m free-space transmission. The net bit rate is improved by more than 45% compared with the conventional FBMC-VLC.