Performance Enhancement for m-Sequence and Hadamard Code SAC-OCDMA Systems Based on Narrowband Filters

In this paper, we examine the performance of a spectral amplitude coding-optical code division multiple access (SAC-OCDMA) system using two different codes: m-sequence and Hadamard. Fiber Bragg grating (FBG) filters and balanced detection technique are employed for performance enhancement. The system performance is evaluated in terms of quality factor (Q), bit error rate (BER) and signal-to-noise ratio (SNR) as a function of number of users and fiber distance. The achieved results using a co-simulation Matlab-Optisystem version 17 are considered as improvements over previous works found in the literature. The results corresponding to a first comparative study of the system performance using the both code sequences show that using Hadamard code yields a better BER performance than using m-sequence code. This led us to study the performance of the proposed system for a larger number of users using the Hadamard code of length L = 32 (m = 5). The simulation results reveal that at a data rate of 100 Mbits/s and a FBG bandwidth of 0.4 nm, the suggested SAC-OCDMA system may support up to 13 users with a transmission distance of 5 Km. The obtained results also show that a distance of 45 Km can be used for a number of users up to 8 with BER = 9.8E − 09, Q = 5.82 and SNR = 20.71 dBm.