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dc.contributor.authorSales Llopis, Martinen
dc.description.abstractAs global IP traffic grows unceasingly, optical networks demand for technology upgrades in order to keep the feared “capacity crunch” away. The most celebrated technologies of coherent detection and wavelength-division multiplexing (WDM), widely deployed in long-haul links, are gaining ground in access networks, which is particularly challenging due to the shared-cost requirements, leading to denser channel spacings and the use of cheaper devices that tend to be noisier. In order to make the most of this technology combination, it is crucial to have a model of the channel that accurately describes all the present sources of noise. Traditionally, the most used model has been the additive white Gaussian noise (AWGN) channel, which, although only accounting for a linear contribution of complex noise and being insensitive to rotational phenomena, has shown its validity in numerous studies, as well as in commercial equipment. In this thesis, however, it is observed that the adoption of coherent detection and WDM, with lower-grade semiconductor lasers showing a moderate linewidth, yields scenarios where a phase-sensitive model becomes a must. The partially coherent AWGN (PCAWGN) channel is a popular choice that fulfils this need, but its high complexity due to non-trivial functions involved, deprives it from being suitable in high-speed digital circuits. The main goal of this thesis is to describe a reduced-complexity approximation in polar coordinates, accurate enough to find its applicability in modern systems. Furthermore, this works explores some possible end-to-end applications, like channel capacity estimation or symbol detection, assessing its performance by means of extensive simulations. Lastly, the emerging field of complex modulation of directly modulated lasers is revisited, with a special interest in how the proposed approximation can help to improve the performance of previously reported techniques, as well as proposing a new way to design spiral-shaped constellations aimed to maximise the channel capacity.en
dc.rightsAll rights reserveden
dc.rightsAll rights reserveden
dc.rightsAll rights reserveden
dc.rightsAll rights reserveden
dc.subjectOptical communicationsen
dc.subjectPhase noiseen
dc.subjectPartiallly coherent channelen
dc.titleOptical fibre communication over a noisy partially coherent channelen
dc.type.qualificationnameDoctor of Philosophy (PhD)en
dc.publisher.institutionUniversity of Cambridgeen
dc.publisher.departmentDepartment of Engineeringen
dc.contributor.orcidSales Llopis, Martin [0000-0002-5906-5680]
dc.publisher.collegeDepartment of Engineering
dc.type.qualificationtitlePhD in Engineeringen
pubs.funder-project-idEPSRC (EP/L026155/2)
pubs.funder-project-idEC FP7 MC ITN (608099)
cam.supervisorSavory, Seb J

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