Performance Analysis of SAC OCDMA Systems based on New Coding Scheme

Optical code-division multiple-access (OCDMA) has been recently proposed as an alternative to frequency and time based multiple, and multiplexing methods for next generation high speed optical �ber networks. This is because OCDMA allows many users to access the same optical �ber channel asynchronously through the assignment of unique code words sequences. Furthermore, OCDMA offers strong security in the physical layer. Due to these reasons, OCDMA has been recognized as one of the most important technologies for supporting many users in shared media at the same time. In conventional multiple access techniques such as time division multiple access (TDMA) and wavelength division multiple access (WDMA), the maximum transmission capacity is determined by the total number of the slots while for optical CDMA the transmission capacity depends on the number of active users. Spectral amplitude coding optical code division multiple access (SAC-OCDMA) systems attract more attentions since the multi user interference (MUI) can be completely eliminated by spectral coding existing in conventional systems. MUI can be reduced by using subtraction technique. EDW (Enhanced Double Weight) code based OCDMA is analyzed here. Four detection techniques, such as direct detection, complimentary detection, AND detection and NAND detection are compared. The simulations are carried out using Optisystem version12. The analysis has revealed that NAND subtraction detection technique exhibits better results.