Performance Optimization of RSOA Based High Speed Backhaul XG-PON Hybrid (DWDM-PON/ FSO) Network

Abstract

In today’s growing world there is an increasing demand for high speed connections for services like television (IPTV) and video on demand (VoD) over Internet together with high speed Internet access (HSI), to which the best solution is Fiber based access networks. Fiber to the Home (FTTH) is probably the most suitable option for a long reach network with high bandwidth demand. Passive Optical Networks (PON) use components that are high in reliability, have low cost and passive functionality. It is a shared network that uses multiplexing to send the data of multiple users through Optical Line Terminal (OLT) to different Optical Network Units (ONUs).Each ONU reads the contents of only those packets that are addressed for it .PON has evolved through different variants in the past few decades however, Gigabit passive optical network (GPON) is receiving great acceptance throughout the world. Although fiber optical networks have low capital expenditure in comparison to other technologies, its deployment is still considered to be a tedious and high cost act in certain areas like railway lines, buildings, disaster stricken areas etc. For such situations, a hybrid access network consisting of both wired and wireless links is required. Free Space Optics (FSO) has evolved as a compromise to cabling. In comparison to traditional radio link this optical wireless link offers greater bandwidth and its operation in license free spectrum which is important reduction in cost. For multi channel transmission Dense Wavelength Division Multiplexing (DWDM) is a promising technique that allows multiple users to transmit data simultaneously through a single fiber via different wavelengths. Thus, this Thesis work presents the results derived from the performance optimization set-up of DWDM based next-generation passive optical network (XG-PON) network that are the next generation broadband access networks. It is a hybrid 8 user network as few ONU’s are communicated via FSO which is preferred last mile solution, with demonstrated downstream data rate of 40Gbps and upstream data rate of 10 Gb/s. Reflective Semiconductor Optical Amplifier (RSOA) has been made as a cost effective choice for upstream data transmission which has a fast gain recovery governed by phonon- carrier interactions and carrier-carrier scattering, thus making it operate at data rates ≥ 10 Gb/s. Impacts of various design parameters and impairments have been exploited to result in an optimized performance. The different parameters targeted for optimization were modulation formats both for upstream and downstream, data rates, total network length, filter type and dispersion compensation. For a cost effective system RSOA was used, performance of system by varying Imod current, pumping current and extinction ratio was also monitored. The simulations gave us encouraging results under certain condition which have been discussed in this thesis.