Performance Study Of Broadband Capable Colorless WDM Passive Optical Network

In optical fiber access networks, researchers are continuously developing higher capacity transmission systems due to development of many high speed applications and services. Residential broadband services such as Cable Television (CATV), High Definition Television (HDTV), e-learning&telemedicine etc are increasingly being seen as a catalyst for general economic growth. To reduce the high CAPEX involved, researchers have now developed techniques to use single fiber for full duplex transmission in PON. To address these problems, this paper mainly focus on the usage of single feeder fiber arrangement for broadband access, mitigating the impairments especially the problem of Rayleigh backscattering which is the main cause of signal degradation in single fiber architecture, with the help of the simulated models, high-tech research and usage of analytical tools such as Q-factor, BER and eye diagrams " Performance Study of Broadband capable colorless WDM PON". Various innovative research achievements were obtained during this work.The major work and novel contributions of this dissertation is the assortment of colorless WDM-PON to carry the modern day broadband services based on simulation models, comparative analysis and transmission impairments mitigation methods. Various arrangements are studied and modeled on the simulation platform of colorless wavelength division multiplexed passive optical network. The details are listed below.In our dissertation firstly we take into consideration the receiver design by employing Arrayed Waveguide Gratings (AWG) for simultaneous demultiplexing and demodulation of wave length division multiplexed (WDM) return-to-zero differential phase-shift keying (RZ-DPSK) signal. We achieved a simple and flexible WDM system that uses the above mentioned property of AWG resulting in utilization of a single AWG at10-Gbps data rate using ITU grid of100GHz channel spacing for RZ-DPSK signal without using any additional demodulation devices. Hence this scheme is cost effective in terms of component counts and results in improved receiver sensitivity.Secondly based on the selection of AWG for simultaneous demodulation and demultiplexing we investigated the impact of Rayleigh backscattering RBS impairment on both single and dual feeder fiber AWG based WDM-PON architectures and then analytically compared both of them. To obtain optimum performance of both downstream and upstream transmission in WDM PON we modeled, simulated and analyzed a single feeder fiber colorless WDM-PON architecture traversing a distance of25Km and can successfully sustain RBS induced noise and was analytically compared with the dual feeder fiber arrangement. The implementation of single feeder fiber significantly reduces the Capital Expenditure CAPEX for deploying a cost effective colorless WDM PON but we have to take into account different techniques to mitigate RBS.Thirdly based on the selection of single feeder fiber architecture due to cost effectiveness after the analytic comparison of both architectures, the prime issue of mitigating Rayleigh backscattering RBS mitigation in the single feeder fiber architecture was analyzed and different methods previously used were discussed briefly. After reviewing the different techniques of RBS mitigation we proposed a novel idea of Phase remodulation based on Time Interleaving between downstream and upstream signals to mitigate RBS noise. The network architecture was modeled&analysis demonstrated that the high extinctions ratio in both RZ-shaped DPSK downstream and time interleaving remodulated upstream data signals help to increase the tolerance to RBS induced noise. Moreover in addition to RBS mitigation we have also attained simplicity of WDM PON in terms of hardware utilization. i.e instead of DPSK receiver simple PIN type Photo Diode PD is used thereby making the receiver more simple.Fourthly in addition to the achievement of cost effective single fiber colorless WDM PON architecture we then achieved a cost effective full duplex WDM-PON architecture supporting both point-to-point and broadcasting services. Error free transmission of10Gbps point-to-point data and2.5Gbps broadcasting services in a colorless WDM-PON was achieved in a distance of25Km with lower BER.