Independent component analysis for preprocessing optical signals in support of multi-user communication

Free Space Optical (FSO) communication is widely recognized for its powerful features, especially when compared to other wireless technologies utilized in point-to-point communication links. Although current literature focuses primarily on point-to-point transmission, multi-user FSO systems are beginning to draw significant attention. The primary objective in a multi-user communication system is to estimate individually transmitted signals from received signals, namely Blind Source Separation (BSS). A solution to the BSS problem in an FSO multi-user communication link is proposed. A multi-point FSO system composed of two independent transmitters operating at different wavelengths and a dual path fiber bundle receiver was used. The FastICA algorithm was exploited for multi-user detection. Experimental results demonstrate that this method can separate original transmitted signals from their received mixtures. Effects of signal power, data rate, misalignment error, and turbulence severity on signal separation are also explored to define the working range for achieving best performance.