Investigation on Radio over Fiber Networks Using Various Modulation Schemes

Abstract

Radio over fiber is a potential solution to meet up with the growing internet bandwidth demand. It is a spectacular combination of both optical and wireless communication. A radio over fiber system supports convergent network architecture, which by exploiting the benefits of both optical and wireless technologies, provides multiple services to both mobile and fixed users. The applications that require bandwidth up to 1Gbps for operation such as, WiMAN and WiMax are well supported by radio over fiber network. The execution of radio over fiber network can be further enhanced by using several techniques such as, wavelength division multiplexing, time division multiplexing, orthogonal frequency division multiplexing, optical code-division multiplex access, wavelength reuse scheme, etc. The objective of this dissertation is to analyze the performance of radio over fiber system when integrated with various modulation schemes. Firstly, a bidirectional radio over fiber wavelength division multiplexing passive optical network is proposed using subcarrier multiplexing/amplitude shift keying technique. A narrow wavelength spacing of 0.4nm is maintained between the subsequent channels to enhance the capacity of the system. The proposed system offers acceptable values of Q-factor and bit error rate for both the uplink and downlink signals up to a transmission distance of 50km. Secondly, a cost-effective full duplex radio over fiber passive optical network is proposed based on wavelength remodulation using fiber Bragg grating. Simulation of the proposed system demonstrates 1Gbps uplink and 1Gbps downlink signals sharing the same continuous wave laser source located at the remote central station. The system exhibit smooth execution up to a transmission distance of 100km and henceforth, is capable of supporting long haul transmissions. Thirdly, the effects of four wave mixing (FWM) is mitigated up to 30dBm in a wavelength division multiplexing radio over fiber network by using hybrid four wave mixing suppression modules. Thus, in this dissertation the execution of radio over fiber network is investigated and is further improved by integrating radio over fiber with various modulation schemes.