Mode division multiplexing zero forcing equalisation scheme using LU factorization

Optical networks is considered as the main backbone networks that handled the Internet traffic worldwide. Currently, the Internet traffic has had huge annual growth due to the increment in connected devices. At this rate, it is believed that the current technology in optical network will not able to...

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Main Author: Mohamed, Ahmed Sayed
Format: Thesis
Language:eng
eng
Published: 2016
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https://etd.uum.edu.my/6565/2/s818382_02.pdf
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institution Universiti Utara Malaysia
collection UUM ETD
language eng
eng
advisor Amphawan, Angela
topic TK5101-6720 Telecommunication
TK5101-6720 Telecommunication
spellingShingle TK5101-6720 Telecommunication
TK5101-6720 Telecommunication
Mohamed, Ahmed Sayed
Mode division multiplexing zero forcing equalisation scheme using LU factorization
description Optical networks is considered as the main backbone networks that handled the Internet traffic worldwide. Currently, the Internet traffic has had huge annual growth due to the increment in connected devices. At this rate, it is believed that the current technology in optical network will not able to handle this growth in the near future. Till recently, multiplexing techniques in the optical communication rely on modulation techniques where polarization, amplitude and frequency of the signal are used as the main data carrier. In these techniques, light modes are considered as an undesired effect causing modal dispersion. In contrast, mode division multiplexing (MDM) was introduced as a multiplexing approach which relies on the utilization of the light modes for the benefit of increasing the capacity-distance product of the optical network. As per any new technology, it is still facing a lot of problems preventing it from being commercially standardized and used. One of the main MDM issues is the mode coupling, which is an inventible phenomena occurs when the energy of one mode transfers to another mode during their propagation throughout the optical fibre causes inter-symbol interference (ISI), increasing the bit error rate (BER) and reducing the overall system performance. Different equalization schemes have been proposed so far attempting to mitigate the effect of mode coupling on the MDM optical signal. However, they suffer from high computational complexity and rely on training signals in estimating the optical channel which increases the overhead payload. These technique mainly rely on Least Mean Squared (LMS) and Recursive Least Squared (RLS) algorithms. The purpose of this study is to introduce a Zero Forcing LU-based equalization scheme for MDM. Previous research in the radio domain on multiple-input multiple output (MIMO) and orthogonal frequency division multiplexing (OFDM) demonstrated that zero forcing schemes have low computational complexity compared to current schemes as they equalize the signal without training signals, thus reducing the overhead payload. All of the previous points motivate the work of this study to adapt this approach in optical communications. The study adopts the four stages of the Design Research Methodology (DRM). The initial data was collected from the optical simulator, processed and used to derive the transfer function (H) of the system. Then it was used to develop the equalization scheme in MATLAB. The experimentation on Zero Forcing LU based equalization scheme shows O(N) complexity which is lower than RLS which has O(N2) and faster than LMS, in fact, LMS needs an average of 0.0126 seconds to process the signal while ZF LU-based needs 0.0029 seconds only. On the other hand, the proposed equalization reduces the time delay spread of the channel, resulting three times increment in the capacity of the MDM channel and even lower computational complexity. The main contribution of this study is the reduction of the computational complexity of the previous equalization schemes in MDM. Applying this scheme in real MDM systems can produce more cost effective and smaller digital signal processing (DSP) parts for MDM equipment and can accelerate the work on the standardization of MDM for being commercially used as a multiplexing technique for optical communication networks.
format Thesis
qualification_name masters
qualification_level Master's degree
author Mohamed, Ahmed Sayed
author_facet Mohamed, Ahmed Sayed
author_sort Mohamed, Ahmed Sayed
title Mode division multiplexing zero forcing equalisation scheme using LU factorization
title_short Mode division multiplexing zero forcing equalisation scheme using LU factorization
title_full Mode division multiplexing zero forcing equalisation scheme using LU factorization
title_fullStr Mode division multiplexing zero forcing equalisation scheme using LU factorization
title_full_unstemmed Mode division multiplexing zero forcing equalisation scheme using LU factorization
title_sort mode division multiplexing zero forcing equalisation scheme using lu factorization
granting_institution Universiti Utara Malaysia
granting_department Awang Had Salleh Graduate School of Arts & Sciences
publishDate 2016
url https://etd.uum.edu.my/6565/1/s818382_01.pdf
https://etd.uum.edu.my/6565/2/s818382_02.pdf
_version_ 1747828093237592064
spelling my-uum-etd.65652021-04-06T06:31:57Z Mode division multiplexing zero forcing equalisation scheme using LU factorization 2016 Mohamed, Ahmed Sayed Amphawan, Angela Awang Had Salleh Graduate School of Arts & Sciences Awang Had Salleh Graduate School of Arts and Sciences TK5101-6720 Telecommunication QA75 Electronic computers. Computer science Optical networks is considered as the main backbone networks that handled the Internet traffic worldwide. Currently, the Internet traffic has had huge annual growth due to the increment in connected devices. At this rate, it is believed that the current technology in optical network will not able to handle this growth in the near future. Till recently, multiplexing techniques in the optical communication rely on modulation techniques where polarization, amplitude and frequency of the signal are used as the main data carrier. In these techniques, light modes are considered as an undesired effect causing modal dispersion. In contrast, mode division multiplexing (MDM) was introduced as a multiplexing approach which relies on the utilization of the light modes for the benefit of increasing the capacity-distance product of the optical network. As per any new technology, it is still facing a lot of problems preventing it from being commercially standardized and used. One of the main MDM issues is the mode coupling, which is an inventible phenomena occurs when the energy of one mode transfers to another mode during their propagation throughout the optical fibre causes inter-symbol interference (ISI), increasing the bit error rate (BER) and reducing the overall system performance. Different equalization schemes have been proposed so far attempting to mitigate the effect of mode coupling on the MDM optical signal. However, they suffer from high computational complexity and rely on training signals in estimating the optical channel which increases the overhead payload. These technique mainly rely on Least Mean Squared (LMS) and Recursive Least Squared (RLS) algorithms. The purpose of this study is to introduce a Zero Forcing LU-based equalization scheme for MDM. Previous research in the radio domain on multiple-input multiple output (MIMO) and orthogonal frequency division multiplexing (OFDM) demonstrated that zero forcing schemes have low computational complexity compared to current schemes as they equalize the signal without training signals, thus reducing the overhead payload. All of the previous points motivate the work of this study to adapt this approach in optical communications. The study adopts the four stages of the Design Research Methodology (DRM). The initial data was collected from the optical simulator, processed and used to derive the transfer function (H) of the system. Then it was used to develop the equalization scheme in MATLAB. The experimentation on Zero Forcing LU based equalization scheme shows O(N) complexity which is lower than RLS which has O(N2) and faster than LMS, in fact, LMS needs an average of 0.0126 seconds to process the signal while ZF LU-based needs 0.0029 seconds only. On the other hand, the proposed equalization reduces the time delay spread of the channel, resulting three times increment in the capacity of the MDM channel and even lower computational complexity. The main contribution of this study is the reduction of the computational complexity of the previous equalization schemes in MDM. Applying this scheme in real MDM systems can produce more cost effective and smaller digital signal processing (DSP) parts for MDM equipment and can accelerate the work on the standardization of MDM for being commercially used as a multiplexing technique for optical communication networks. 2016 Thesis https://etd.uum.edu.my/6565/ https://etd.uum.edu.my/6565/1/s818382_01.pdf text eng public https://etd.uum.edu.my/6565/2/s818382_02.pdf text eng public masters masters Universiti Utara Malaysia [1] S. Ö. Arik, J. M. Kahn, and K. P. Ho, "MIMO signal processing for modedivision multiplexing: An overview of channel models and signal processing architectures," IEEE Signal Processing Magazine, vol. 31, pp. 25-34, 2014. [2] CISCO, "The Zettabyte era: trends and analysis," 2015. [3] D. J. Richardson, J. M. Fini, and L. E. Nelson, "Space division multiplexing in optical fibres," Nature Photonics, vol. 7, pp. 354-362, 2013. [4] R. Ryf, S. Randel, A. H. Gnauck, C. Bolle, A. Sierra, S. 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