A Comparative Performance Assessment between Pre-equalization and Post-equalization Techniques in m-CAP Indoor VLC Systems with Bit Loading

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 scheme 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 .