Experimental Demonstration of Diversity Combining for Asymmetrically Clipped Optical OFDM

Experimental results demonstrating the use of diversity combining in an optical wireless system using asymmetrically clipped optical orthogonal frequency division multiplexing (ACO-OFDM) are presented. A standard white lighting LED of the type often used in visible light communications (VLC) is used as the transmitter. The experiments show that diversity combining gives an improvement of 2-3 dB, and that uncorrected DC offset in the receiver can cause diversity combining to fail, but that DC correction methods are effective. It is shown that diversity combining changes the frequency distribution of noise received on the even subcarriers.