PERFORMANCE ANALYSIS OF SEVERAL QUASI-ORTHOGONAL CODES OPTICAL CDMA FOR RADIO-OVER-FIBER SYSTEM

Abstract

An optical code-division multiple-access (OCDMA) network for radio-over-fiber (RoF) transmissions was proposed. The network encoders/decoders (codecs) were structured based on arrayed-waveguide-grating (AWG) routers coded using modified prime codes (MPCs). In the proposed system, the lower in-phase cross correlation could reduce the beating noise, and in the proposed study, its performance was compared with that of a conventional system that uses M-sequence and Walsh-Hadamard codes. The performance of both systems was numerically evaluated by analyzing the effect of phase-induced-intensity noise (PIIN). The results showed that the new code families that had lower cross correlation can suppress the intensity of the noise and effectively cancel out the multiple-access interference (MAI) in balanced detection processes, which improved system performance. By using the proposed MPC-coded OCDMA ROF network codecs, each network required only two AWG routers to accomplish the spectral coding of radio base stations (RBSs) and the decoding of control stations (CSs), resulting in a simple and low-cost system. Therefore, it is possible to produce interference- and crosstalk-free optical CDMA systems for RoF transmissions.