Mahdi Nassiri - Department of Electrical Engineering, University of Guilan, Rasht, Iran
Saeed Ashouri - Department of Electrical Engineering, University of Guilan, Rasht, Iran
Gholamreza Baghersalimi - Department of Electrical Engineering, University of Guilan, Rasht, Iran
Zabih Ghassemlooy - Optical Communications Research Group, Faculty of Engineering and Environment, Northumbria University, Newcastle, UK

This paper demonstrates the superiority of zero-forcing (ZF) pre-equalizer over post-equalizer for the multi-band carrierless amplitude and phase (m-CAP) modulation cheme in the visible light communications (VLC) system. The VLC channel is generated based on iterative site-based modeling for a medium sized room. For the LED bandwidth of 3.5 MHz and different number of subcarriers m = {1, 2, 5} we show the bit error rate (BER) and the error vector magnitude (EVM) of m-CAP with ZF pre- and post-equalizer for a system bandwidth of 15 MHz. Results show that, a BER of 10-4 can be achieved for the pre-equalized m-CAP system, which is well below the 7% forward error correction(FEC) BER limit of 3.8×10-3.

Visible light communications; Multi-band carrierless amplitude and phase modulation; ZF pre-equalizer; ZF postequalizer ; Iterative site-based method; Bit loading