PERFORMANCE ANALYSIS OF WIRELESS AND DISPERSION COMPENSATED OPTICAL COMMUNICATION SYSTEM

Abstract

A communication system in which light is used to carry a stream of information is called Optical Communication System. A modern optical communication system consists of optical fiber, optical amplifier, switches, laser and different advanced technologies for setup a communication link. In this dissertation most of the work focuses on the performance analysis of fiber optical communication system and wireless optical communication system. Over long transmission distances, the use of an erbium-doped fiber amplifier (EDFA) reduces attenuation in the information signal. Non-linearities in the fiber cause dispersion. Some common techniques for reducing dispersion effects in fiber-optic communications are dispersion compensated fiber (DCF) and fiber Bragg gratings (FBG). The research nowadays focuses more on less complex system with higher achievable data rates and optical wireless communications (OWC) is a viable alternative for both inside and outside high-speed wireless access. These laser-based systems provide a low-cost framework link with high data rates (up to 10 Gbit/s) and could be a solution to the high bandwidth constraint. The first part research work of this dissertation describes different types of DCF techniques using cascaded uniform and chirped FBGs. The proposed models are composed of four consecutive uniform FBGs connected to the transmitter. The transmitter is modulating the amplitude of signal and the use of DCF with cascaded FBG enhances the overall system performance. No matter how much dispersion is reduced but the fibre optical communication has issues of complexity, high cost of implementation and prone to cable damage (interference) while implementing them physically. So, the next part of the project focuses on wireless optical communications like OWC channel which can reduce the issues of fibre optic communications. OWC system under environment choppiness is implemented using a iv wavelength division multiplexing (WDM) method. WDM is employed to increase signal strength using optical amplifiers, resulting in a better signal to noise ratio at the receiver. A WDM OWC system based on hybrid optical amplifier configurations is suggested, which offers a viable option for low-cost and high-efficiency systems. The simulation is done on Opti system 7.0 software. The software is used to compare the results of DCF technology for pre, post, and balanced fibre arrangement with and without cascaded FBGs at a rate of 10 Gbps on a 120 km SMF and to enhance the Q—factor and reduce the BER of WDM OWC system under rain and dust. The benefits of high Q-factor and less BER achieved using OWC are further experimented by using modulation techniques like amplitude shift keying (ASK) and physical shift keying (PSK). This also removes complexity of using free space optics (FSO) in the channel. EDFA amplifiers are also used and a comparison study is conducted to determine which modulation technique is more effective for communication. This part of the research examines the performance of an OWC system based on ASK and PSK modulation techniques by varying OWC parameters under various atmospheric conditions such as rain, mist, haze, and snow. Finally, the simulation results are discussed and analysed.