# Optical Code Construction of 2D Spectral/Spatial BIBD Codes for SAC-OCDMA Systems
## 6 Conclusions  
In this study, a new 2D code extended from 1D-BIBD codes was proposed, and its performance was analyzed using theoretical, numerical analysis, and simulations. We designed the SAC based OCDMA system architecture with the help of the proposed 2D-BIBD code. Results of the proposed 2D-BIBD code were compared with existing 2D spectral/spatial codes such as DEU and DPD. 2D-BIBD surpassed the 2D-DEU and 2D-DPD code's performances, which indicated that there was a cardinality enhancement of 72% and 22%, respectively, for the proposed code when compared to 2D-DEU (25 versus 90 active users) and 2D-DPD (70 versus 90 active users) and for the same transmission conditions. Performance analysis of the proposed 2D-BIBD code showed a reduction in MAI and its associated PIIN effects. These effects were generated by the overlapping of chip spectra among signature code sequences, and their effects can be compensated by the low cross-correlation properties of the 2D-BIBD code. This resulted in improved system performance in terms of the maximum code cardinality and BER. Results showed that the 2D-BIBD based system provides high spectral density and offers solutions for the limited bandwidth of light sources. It was also observed that the system capacity and data  
Figure 9: Data rate versus: (**a**) Q factor, (**b**) BER for six users at \(-10\) dBm received power.  
transmission rates were increased with the increase in the spatial length. Results show that our proposed code provided practical code length with minimum cross-correlation and resulted in the minimum probability of error and MAI. Our results were validated with simulation analysis and agreed with the performance of the proposed code for low-error transmission.  
The numerical analysis concluded that the proposed code provided better BER and SNR performance when compared to other 2D codes, for instance, 2D-DPD and 2D-DEU. In addition, the proposed code provided optical transmission performance with minimum \(P_{sr}=-27.5\) dBm when compared to existing 2D-DEU and 2D-DPD codes. Overall, simulation results matched closely with the theoretical analysis. This study suggests that the proposed technique would be useful to increase the spectral width of broadband sources and reduce the need for effective source power with enhancement in spatial code length.  
[PERSON], [PERSON], [PERSON] and [PERSON] designed the research. [PERSON], [PERSON], [PERSON] and [PERSON] performed the code programming. [PERSON] carried out simulation analysis. [PERSON], [PERSON] and [PERSON] performed the analysis of the results and the results interpretation. [PERSON], [PERSON] and [PERSON] wrote the first draft together, supported by [PERSON], [PERSON] and [PERSON] and [PERSON] commented on the draft and all authors finalized it. [PERSON] is the corresponding author. All authors have read and agreed to the published version of the manuscript.  
This work was partially funded by the support program for research and creation development (PSDrc) of the University of Quebec in Chicoutimi.  
Not applicable.  
The authors declare no conflict of interest.