NOISE SUPPRESSION IN 40 GIGABIT-PER-SECOND COHERENT TIME-SPREADING OCDMA SIGNAL TRANSMISSION OVER PASSIVE OPTICAL NETWORK

Abstract

In this dissertation, we studied the OCDMA system over PON at the bit rate per channel of 40 Gbps using Fourier code in order to suppress the noise. We proposed the spreading-time to bit period ratio (SBR) as a factor that can suppress the noise. Our results showed that the highest chip number was resulting in the lowest noise and the BER due to its highest PCR. We further investigated the performance of the system with the different SBR. We performed the mathematical calculation to obtain the noise variance and the BER. The results showed that, in the worst case, and the average case, the BER of the system employing SBR = 0.6, 0.4, and 0.2 was greater than the conventional system using SBR = 1.0, and 0.8. The simulation results confirmed the validity of our mathematical values. Moreover, the comparison between the TDMA and the OCDMA-PON was demonstrated. We showed that the OCDMA-PON was superior in terms of bit rate per subscriber, power budget, and the system complexity at the same bit rate, respectively. Finally, the system verification was proved by performing the experiment. We used the AWG and the PLC en/decoder with the SBR = 0.1 and 0.8. The results had reached and agreement with our mathematical calculation and the simulation, respectively.