Performance analysis of optical atmospheric Turbo-coded 2-D CDMA systems with PPM signaling

This paper proposes Turbo code for optical atmospheric 2-dimensional (2-D) CDMA systems using pulse-position modulation (PPM) signaling. The system performance is theoretically analyzed and the upper bound of bit-error rate (BER) is derived considering the impact of scintillation. The analysis also takes into account various types of interferences and noises such as multiple access interference (MAI), optical beating interference (OBI), and receiver noise. It is shown that system performance is significantly improved when Turbo codes is employed. In particular, the use of Turbo code results in a power gain of 3.5 dB at the BER = 10^-7, the supportable number of users is also increased.