Performance comparison of different detection techniques in long-haul fiber SAC-OCDMA systems

Progress in fiber optic technology have made long-haul communications systems reach distance that were once unheard of. This distance is made possible by using modulation techniques that do not require a complex link design which best applied in spectral-amplitude coding optical code-division multiple access (SAC-OCDMA) system. In this paper, we investigate the use of different detection schemes namely the modified-AND subtraction detection as well as AND subtraction detection for SAC-OCDMA systems. We simulate the system performance of the mentioned detection approaches using OptiSystem7.0 software. The entire effects of fiber nonlinearities, dispersion and attenuation were considered in the simulation of SAC-OCDMA systems. Based on modified double weight (MDW) codes, the simulation results revealed that the modified-AND subtraction detection improves SAC-OCDMA system performance significantly compared to the conventional AND subtraction detection. Moreover, for the same quality of service (QoS) for bit-error rate (BER) of 10^-20 and data rate of 622 Mbps, modified-AND subtraction detection allows longer transmission distance of 30 % in the fiber length as compared to AND detection.