© 2022 IEEE.In this study, BER performance of Flip-OFDM, an efficient unipolar version of OFDM for optical wireless communication systems, and classical VLC-OFDM waveforms are analyzed under the effect of multipath fading. Ceiling bounce and Lambertian channel models are used to generate the optical channel impulse response considering the diffused optical wireless channel configuration. Flip-OFDM and classical VLC-OFDM waveforms, in which M-CSK and M-QAM signal constellations are used, are compared on the BER-SNR performance criterion in the 5-taps diffused wireless optical channel environment. From the obtained numerical results, it is seen that approximately 1 dB SNR difference occurs between M-CSK and M-QAM signal constellations. In addition, it is understood from the results that the Flip-OFDM waveform provides approximately 12 dB more SNR gain than the classical VLC-OFDM waveform at 1E-4 BER level.