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Title: Modelling of impaired system performance in burst mode optical networks
Author: Desai, Priyanka
Awarding Body: University of Nottingham
Current Institution: University of Nottingham
Date of Award: 2012
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All-optical regeneration and optical packet/burst switching (OPS/OBS) are two potential key enabling technologies for the on-going development of all optical networks. OPS/OBS is required to deal with the bursty nature of Internet Protocol packets which are currently electrically packet switched and optical regenerators are necessary for signal quality improvement irrespective whether the system deals with a continuous data stream or packets/bursts. Thus, the work presented in this thesis focuses on 2R burst mode optical regenerators and their cascadeability. Firstly a system level model for the 2R burst mode optical regenerator (BMOR) cascade is provided. An optical limiting amplifier and optical reshaper are defined within the BMOR model. The limiting amplifier is the distinctive feature of BMOR (relative to continuous mode) and deals with the issues of handling incoming packet with the varying power levels. The 2R BMOR cascade model is then used to investigate the ASE noise evolution, and BER performance, in both homogenous and heterogeneous inter-regenerator amplifier cascades. The capability of the limiting amplifiers to adapt with the change in power packet/bursts is shown. The ASE noise accumulation in the mark and space probability density functions and suppression of ASE noise performed by the cascade of BMOR is observed. In addition, the reduction in the BER degradation along the cascade due to the presence of BMOR in the system is also shown. The impact of phase uncorrelated co-channel homodyne and heterodyne (interferometric) crosstalk on the ASE noise redistribution in a 2R BMOR cascade is further investigated. The impact of the interferometric crosstalk on the signal and ASE noise leading to the widening of the mark and space pdfs is studied. The suppression of interferometric crosstalk performed by the 2R BMOR cascades is shown. BER eva1uation is provided along the 2R burst mode regenerator cascade for different crosstalk scenarios in a homogenous and heterogeneous inter-regenerator amplifier cascade. Not only is this work the first inclusion of interferometric crosstalk in 2R BMOR cascades known to the author hut also much of it is transferable to the continuous mode 2R OR case where only very limited investigation has occurred. Furthermore, a FSO optical amplifier cascade is proposed and investigated, firstly in its own right (not least as the optical amplifiers may have regenerator like properties, when operated in gain saturation mode which leads to scintillation suppression) and secondly for application in the 2R BMOR cascade, as a substitute to part of the fibre based inter-regenerator cascade. Additionally, the FSO amplifier cascade can be used as a backup for fibre in continuous as well as packet/burst mode systems. The improvement in the system's performance impaired by scintillations due to atmospheric turbulence is investigated. An average BER and outage analysis for the scintillation impaired system's performance is provided, using a Monte Carlo simulation to model the atmospheric turbulent channel. Further, scintillation suppression can be achieved which is similar to the 2R regeneration process.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available