Contribution of OFDM modulation to improve the performance of non-coherent OCDMA system based on a new variable weight zero cross correlation code

This study aims at proposing a new model of non-coherent spectral amplitude coding optical code division multiple access (SAC-OCDMA) systems merged with adaptive orthogonal frequency division multiplexing (OFDM) modulation based on variable weight zero cross-correlation (VWZCC) code in order to improve quantitative parameters such as the number of simultaneous users, effective power, channel capacity, spectral occupancy, quality of service, and remove the effect of multi-access interference (MAI) and phase induced intensity (PIIN) noise. Furthermore, the signal-to-noise ratio (SNR) expression is derived, as well as, according to the expression of SNR, numerical results are performed in terms of bit error rate and quality factor as a function of various parameters. The results obtained showed that the proposed hybrid (SAC OCDMA/OFDM-VWZCC) system using the single photo-detector (SPD) technique is outperformed compared to OCDMA/OFDM system based on modified double weight (MDW), flexible cross-correlation (FCC), shift zero cross-correlation (shift-ZCC), and multi diagonal (MD) codes; it has saved an effective power of about − 6 dBm, − 4 dBm, − 3 dBm, and − 2 dBm respectively, as well as saving an effective power of approximately − 23 dBm, − 18 dBm, and − 17 dBm compared to conventional OCDMA-MDW, OCDMA-FCC, and OCDMA-VWZCC systems. In addition, the simultaneous capacity of our system is increased by 11 times compared to the OCDMA-VWZCC system, and 27.5 times and 22 times compared to conventional OCDMA-MDW and OCDMA-FCC systems respectively. Moreover, the system capacity is improved 1.28 times, 1.09 times, 1.07 times, and 1.04 times compared to hybrid systems using MDW, FCC, shift-ZCC, and MD codes; besides that, the cardinality is improved 29.41%, and 10 compared to a hybrid system which uses the MDW and FCC codes, as well, 7.84%, and 4.76% compared to a hybrid system using shift-ZCC and MD code. In addition to that, our system is also simulated using Optisystem software, where the results show that the suggested OCDMA/OFDM-VWZCC system reduces network complexity to 50% and gives better performance in terms of bit error rate (BER) and Q factor where it can transmit at a distance of more than 20 km with a BER and Q factor equal to \(1.38\times 10^{-27}\) and 10.81 respectively.