Two dimensional Fixed Right Shift (FRS) code for SAC-OCDMA systems

Abstract

Abstract In this paper a new algorithm to generate two dimensional fixed right shifting (2D-FRS) code sequences is proposed, which is based on spectral/spatial incoherent OCDMA system. The proposed 2D-FRS algorithm is designed using 1D-FRS code with minimum cross correlation (MCC). The 2D-FRS codes enhance the system cardinality and offer elimination capability of MCC and its associated phase induced intensity noise (PIIN). Furthermore, the proposed algorithm allows multiple users with different code sequences to transmit data with minimum likelihood of interference. The architecture of transmitter-receiver structure of spectral/spatial 2D-FRS OCDMA system is presented. Gaussian approximation is used to analyze performance of the proposed 2D-FRS OCDMA system by investigating noise sources at photodiodes (PDs). It is shown that PD-1 and PD-3 have lower contribution in terms of noise power as compared to PD-0 and PD-2 due to division operation in MCC elimination process at the balanced detectors. Simulation results also validates the proposed system for an agreeable bit error rate (BER) of 10−9. It is observed that the 2-D FRS OCDMA system can support a higher number of users in deterministic and stochastic methods compared to the reported techniques such as Diagonal Eigenvalue Unity (DEU) and Two-Dimensional Diluted Perfect Difference codes (2D-DPD codes). The 2D-FRS cardinality surpassing the 2D-DPD and 2D-DEU by ≈71.21% and ≈9.09% respectively at the BER of 10−9. At 622 Mbits/s transmission data rate, the 2-D FRS meets the optical transmission requirements with lowest effective transmitted source power (Psr), −27.5 dBm in comparison to published codes.