Comparison of unipolar codes for DS-OCDMA system

In this work, we describe a Direct Sequence Optical Codes Division Multiple Access (DS-OCDMA) system using unipolar codes which are the Prime Sequence (PS), the Quadratic Codes (QC) and the Extended Quadratic Codes (EQC). The performances comparison of the three family codes, for coherent and incoherent source, shows that the EQC codes offer better results on term of Bit Error Rate (BER) than the two others family codes. In fact this family codes presents the better correlation properties. Moreover, we demonstrate that by controlling the optical bandwidth of the encoders/decoders, we can improve system performances in the case of incoherent source.