SAC-OCDMA system performance using narrowband Bragg filter encoders and decoders

Abstract

In this paper, we have studied a Spectral Amplitude Coding Optical Code Division Multiple Access (SAC-OCDMA) system performance using fiber Bragg gratings equivalent to very narrow filters used in the system as encoders and decoders in both the transmitter and the receiver block. The system performance depends on several variables such as: the optical power; the fiber length; the data rate and the bandwidth. Different simulations have been realized in terms of the bit error rate (BER) and the quality factor (Q) to evaluate the effect of each parameter on the system performance and also to examine the impact of number of users. The obtained results using Optisystem network show clearly that the studied SAC-OCDMA system of three users remains efficient for fiber lengths up to 25 km at a data rate of 200 Mbits/s and a FBGs bandwidth of 0.6 nm. These results are realized with an acceptable bit error rate BER< 10 - 9. In addition, a SAC-OCDMA system of 9 users was also simulated to assess the effect of the number of users. The results obtained show that for a fiber length L = 5 Km, the system remains efficient for a number of users set at 8 users, then the longer the fiber length increases the more the number of possible users decreases. For L = 35 Km, the number of users for whom all users obtain a good BER value is 6 users.