Performance of an optical PPM/CDMA system with turbo coding

In this paper, performance of an optical CDMA system with turbo coding is analyzed and simulated. It is assumed that the optical channel is an intensity-modulated (IM) channel and a direct-detection scheme is employed to detect the received optical signal. The modulation scheme used is pulse-position-modulation (PPM). From the simulation results, it is shown that turbo coding offers considerable coding gain with reasonable encoding/decoding complexity. Also, it is demonstrated that the performance of an optical CDMA system can be substantially improved by increasing the interleaver length and the number of iterations for a fixed code rate. The results in this paper can be applied, for example, to an optical wireless LAN operating in an indoor environment with multiple access applications