BER Performance Analysis of Spectral Phase-Encoded Optical Atmospheric PPM-CDMA Communication Systems

We propose spectral phase-encoded optical atmospheric (OA) code-division multiple-access (CDMA) systems with pulse-position modulation (PPM) and theoretically analyze the bit error rates (BERs). We compare the BERs of the proposed system to those of time-encoded OA-PPM-CDMA systems at the same bit rate and chip rate. We show that, even if the proposed spectral phase-encoded OA-PPM-CDMA system is equipped with no mitigation techniques of multiple access interference (MAI) and scintillation, the proposed system achieves lower BERs than both time-encoded OA-PPM-CDMA systems, both with and without a mitigation technique of MAI/scintillation, due to its higher code spreading gain and higher tolerance to noise.