Optical CDMA system using embedded transmission method with Manchester signaling

Abstract

We propose an optical CDMA system using the embedded transmission (ET) method with Manchester signaling. In the proposed system, transmission bits are embedded in the signature sequence used in optical CDMA systems. Although the Manchester signaling uses two slots for a transmitted bit, the two slots are included in the chip duration of optical CDMA.. According to an embedded bit, an optical pulse is transmitted in either slot. In the receiver, the threshold detection for the embedded bits reduces the effect of multiple access interference (MAI) into the erasure state, which is not a transmitted signal. By using a codeword of the BCH codes as the transmitted bits, the effect of MAI is removed in the decoding procedure of BCH codes. Since the decoding procedure treats the effect of MAI as the erasure bits, instead of the error bits, using extended BCH(eBCH) codes allows us to remove the effect of MAI more efficiently. We analyze the bit error rate (BER) of the system using the ET method with Manchester signaling on the assumption that photodetector outputs obey the Poisson distribution. We show that the system using the ET method with Manchester signaling achieves better BER performance than that without Manchester signaling.