Use of Turbo Coding for Embedded Transmission Scheme in Optical CDMA

We propose using turbo code for the embedded transmission (ET) scheme [1][2] in optical code division multiple access (CDMA). Although the scheme uses pulse position modulation (PPM), to resolve the problem of the vulnerability of the embedded PPM signaling to multiple access interference (MAI), we obtain soft information of the received signal, which is used for turbo decoding. We evaluate the bit error rate (BER) of the proposed scheme, compared the conventional PPM-OCDMA with turbo coding and the ET scheme with BCH coding. Simulation results show that the proposed scheme achieves better BER than the conventional turbo-coded PPM-OCDMA and than the BCH-coded ET scheme.