Performance analysis of two dimensional wavelength/time OCDMA system for optical network

Abstract

The major interference factor in an Optical Code-Division Multiple-Access System (OCDMA) is the noise in the form of Multiple Access Interference (MAI), which induces the occurrence of Bit Error Rate (BER). Phase Induced Intensity Noise (PIIN) is the dominant noise in the receiver that is closely related to MAI. The use of an ideal code with minimum cross-correlation will mitigate MAI, reduce PIIN, and expand code scalability. Many codes have been proposed for One-Dimension (1-D) systems. These involve exploiting the wavelength or time resource. However, some of these codes have fixed or zero cross-correlation property which cancels out the MAI. However, the performance is still affected by the PIIN. 1-D codes need a very long code length when there is a high cardinality. Therefore, the objectives of the thesis are, first, investigate the OCDMA codes to enhance the performance and decrease the required code length, such as the 2-D Perfect Difference (PD) code, and Wavelength/Time (W/T) 2-D Modified Double Weight - MDW), second the implementation and analysis of two-dimensional (2-D) codes for an OCDMA system via simulation. The thesis starts with an explicit construction of an incoherent 2-D MDW OCDMA system with the allocation of wavelength and time dimensions resource to achieving performance goals and design parameters. The study of the properties of the code include a consideration of the scientific functions of the performance by analyzing various parameters such as the output signal spectrum and BER versus the length of the fibre, the number of users, data rate, the use of Avalanche Photo-Detectors (APD) in the receiver, and the effective received power ( srP ). Secondly, the 2-D MDW OCDMA code is designed in simulation.