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Applications of spectrum slicing in optical access networks
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Sun, Shaobo (2010) Applications of spectrum slicing in optical access networks. PhD thesis, University of Warwick.
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Official URL: http://webcat.warwick.ac.uk/record=b2487412~S15
Abstract
Spectrum-slicing (SS) is a novel attractive technique for the implementation of
optical access network. Its main advantage compared to the conventional optical
network is utilizing spectral slices of a broadband source for different data
channels. Since the light sources employed are quite cost effective, this
technology is economically attractive to the modern communication system.
The major objective of this dissertation is to investigate the performance of
systems employing spectrum-slicing, for implementing wavelength division
multiplexing (WDM) and optical code division multiple access (OCDMA) in
optical access systems. The analysis is conducted mainly through the theoretical
model based on the statistics, derived from fundamental chi-square and Gaussian
distribution.
Firstly, the analysis of an SS-WDM system performance when employing an
optical preamplifier receiver is carried out to improve understanding of the SS in
a realistic situation where dispersion significantly impacts the signal in
transmission. It is shown that there exists an optimum optical bandwidth which
minimizes the detection sensitivity for a given error probability caused by two
competing effects of inherent signal fluctuation and dispersion. The optically
preamplified receiver delivers increased transmission capacity and a substantially
improved power budget compared to a pin receiver. The results are obtained
using the saddle point approximation and compared to the customary Gaussian
approximation, which is found to be reasonably accurate in predicting the
optimum bandwidth but conservative in sensitivity predictions.
The second part of the work investigates the performance of an SS-OCDMA
employing and proposes a supporting adaptive coding scheme developed from
prime-hop codes. The concomitant higher-order dispersion, beat noise and
multiple access interference in incoherent OCDMA systems become limiting
factors to the bit error rate. The major thrusts of the new schemes are to alleviate
the performance degradation from these impacts especially to reduce the power
loss and the bit error rate (BER) degradation due to higher-order dispersion.
Performance comparisons between the adaptive PHC and original PHC schemes
indicate that the former is more suitable for use in the considered incoherent
system in terms of accommodating more users for a given BER. The proposed
adaptive method can be universally applied to mitigate dispersion effects in the
similar 2-D OCDMA systems.
Within the last part of the work, regular low-density parity-check (LDPC) codes
are applied for the first time to a SS-WDM system. An adaptive decoding
algorithm of low density parity check (LDPC) codes based on the precise SSWDM
noise statistics is developed, which outperforms the decoding with
conventional Gaussian model. The simulation results for various code rates show
that such a forward error correction scheme provides significant coding gain for a
dedicated system in terms of improving the overall transmission capacity and
available power budget. The adaptive algorithm of LDPC codes can be
generically applied to all the asymmetric channels.
Item Type: | Thesis (PhD) | ||||
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Subjects: | T Technology > TK Electrical engineering. Electronics Nuclear engineering | ||||
Library of Congress Subject Headings (LCSH): | Optical communications -- Mathematical models | ||||
Official Date: | December 2010 | ||||
Dates: |
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Institution: | University of Warwick | ||||
Theses Department: | School of Engineering | ||||
Thesis Type: | PhD | ||||
Publication Status: | Unpublished | ||||
Supervisor(s)/Advisor: | Leeson, Mark S., 1963- | ||||
Extent: | xiv, 204 leaves : ill., charts | ||||
Language: | eng |
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