Abstract
Exploitation of the spectral/spatial two dimensional optical code division multiple access (2D-OCDMA) systems in passive optical networks (PONs) is not explored extensively due to the fact spatial encoding requires deployment of multiple star couplers in the topology where each coupler is connected to different ends of either transmitter or receiver nodes. As a result, this scheme is not suitable for PON applications because it requires a significant increase in the amount of fiber deployment within the network along with the complexity of implementation to deploy the required star couplers. To deploy spectral/spatial OCDMA systems at PON and reduce the impact of fiber strands, this work proposes and investigates an optimized architecture of 2D-OCDMA for PONs based on enhanced multi-diagonal (EMD) code. Spectral/spatial encoding technique is used to develop 2D-EMD coding algorithm from the existing 1D-EMD scheme. This operation elevates orthogonality between the adjacent codes and supports high capacity through superior noise mitigation at the receiving end. A complete system architecture is developed and implemented in an excessively used software for optical networks implementation and analysis called Optisystem, for analysis under different performance parameters of PON. It is observed that the proposed system provides better performance in terms of transmission capacity, and cardinality, in comparison with existing 1D-EMD code and other 2D-OCDMA counterparts. Analysis shows that for an agreeable BER of 10-9 the proposed system can support 192 subscribers each communicating at 2 Gbps of data over 25 km single mode fiber. In terms of capital expenditure (CAPEX), four times cost saving per user is achieved for proposed architecture (PA) over conventional architecture (CA) for nearly similar performance.