Analysis of the higher order signals in fiber optic code-division multiple access networks using series coupler access encoder and series coupler access decoder

Abstract

Fiber optic code-division multiple access (FO-CDMA) networks using optical series coupler access encoders (SCAEs) and series coupler access decoders (SCADs) are analyzed considering the higher order signals of the optical matched filter. By mathematically interpreting the inevitable interference effect of the higher order signals up to the third order, we found that the performance of the FO-CDMA networks could be seriously degraded due to the sidelobe peaks increased by the higher order signals. We also found that the interference signal intensities increase according to the increase of coupling coefficient (?). Compared with the conventional analysis without considering the higher order signals, the peak-to-sidelobe ratio considering the higher order signals is degraded, for example, by 3.75 dB for N(coupler number) = 5, ? = 0.5, and the code length of 341.