Performance enhancement of SAC-OCDMA system using modified-AND subtraction detection

Technology is already on the move towards exploiting the limits of the fiber´s physical properties and more sophisticated techniques will be needed to increase the throughput and counteract the transmission impairments. In this paper, we present a new detection technique called the modified-AND subtraction detection for spectral-amplitude coding optical code-division multiple access (SAC-OCDMA) systems. This detection technique is based upon decreasing the received signal strength to the decoder´s branches by dividing the weight of the utilized code sequence. The new technique is capable of mitigating the intensity and shot noise impacts, as well as eliminating the multiple access interference (MAI) influence. We simulate the system performance of the proposed detection technique using OptiSystem 9.0 software. The entire practical effects of fiber nonlinearities, dispersion and attenuation were considered in the simulation of SAC-OCDMA system. Based on modified double-weight (MDW) code, the simulation results revealed that the modified-AND subtraction detection improves SAC-OCDMA system performance significantly compared to the conventional AND subtraction detection.