Fig. 1. Schematic diagram of the multi-band Nyquist PAM-8 system.

Fig. 2. Spectra of Nyquist PAM compared with traditional PAM.

Fig. 3. Spectral shape of Nyquist PAM considering different roll-off factors.

Fig. 4. Experimental setup of the multi-band VLC system based on Nyquist PAM-8 modulation. (a) Measured electrical spectra without weighted pre-equalization; (b) measured electrical spectra with weighted pre-equalization; (c) experimental setup. Eq., pre-equalizer.

Fig. 5. Measured frequency response of the overall VLC system.

Fig. 6. BER performance versus the bandwidth of the guard band.

Fig. 7. Measured electrical spectra of received signal (a) without filters, (b) with the rectangular filter in frequency domain, and (c)–(h) with the Nyquist filter at different roll-off factors. BW, bandwidth.

Fig. 8. Measured results: (a)–(c) BER performance versus different filters for sub-bands 1–3. (d) Highest baud rate and spectral efficiency achieved for the system utilizing Nyquist filter with different roll-off factors.

Fig. 9. Measured electrical spectra with N=1−6 sub-bands.

Fig. 10. Measured BER performance of each sub-band for different numbers of sub-bands.

Fig. 11. Total capacity of multi-band system for different numbers of sub-bands.