Modeling and mitigation of spectral crosstalk in OFDM WDM-VLC system

The present work deals with the thorough modeling of the wavelength division multiplexing (WDM) associated with orthogonal frequency division multiplexing (OFDM) in visible light communication (VLC) systems to evaluate and mitigate the spectral crosstalk (SC). The SC generated by the spectral overlap can degrade the performance of the WDM-VLC system since the adjacent WDM channels can generate considerable interference in the channel of interest. The system is fully modeled with the dual optical diversity (DOD) considering red–green–blue (RGB) color commercial LEDs, their respective color filters, photodiodes and other components of the system from the measurement of its optical quantities and also considering standard features from its datasheets. In the models, the non-ideal behaviors of these components were considered, such as the responsiveness curve of the photodiodes. A more realistic model for the transmittance of optical filters is also proposed. The parameters of WDM channels are estimated by the proposed SC mitigation scheme, allowing the suppression of substantial part of the SC at the receiver side by subtracting interfering signals deploying an zero-forcing (ZF) and a minimum mean-squared error (MMSE) equalizers. The proposed system was simulated whose results demonstrate its effectiveness by evaluating the bit error rate (BER). •The spectral overlap emitted by LEDs can generate crosstalk interference.•The mismatch of the optical filter with the LED can generate greater crosstalk.•The transmissivity of optical filters can be modeled with logistical functions.•MIMO post-equalization allows to mitigate spectral crosstalk in WDM systems.•The estimation of the channel information matrix allows MIMO post-equalization.