LDPC-Coded Modulation Performance Analysis and System Design

In this work, the low-density parity-check (LDPC)-coded modulation scheme which has been selected for inclusion in the next generation of International Telecommunication Union (ITU) broadband standard is investigated. The multi-level mapping of this scheme offers excellent performance along with a s...

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Main Authors: Cornelius Tomas Healy, Anas Al Rawi, Charalampos C. Tsimenidis
Format: Article
Language:English
Published: IEEE 2020-01-01
Series:IEEE Access
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Online Access:https://ieeexplore.ieee.org/document/9258897/
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author Cornelius Tomas Healy
Anas Al Rawi
Charalampos C. Tsimenidis
author_facet Cornelius Tomas Healy
Anas Al Rawi
Charalampos C. Tsimenidis
author_sort Cornelius Tomas Healy
collection DOAJ
description In this work, the low-density parity-check (LDPC)-coded modulation scheme which has been selected for inclusion in the next generation of International Telecommunication Union (ITU) broadband standard is investigated. The multi-level mapping of this scheme offers excellent performance along with a straightforward modulation which is separable into simple one-dimensional schemes. A subset of modulated bit positions are protected by the LDPC code, while the remaining positions benefit from improved Euclidean distance through assignment to distinct constellation regions. To date, there has been a lack of analytical treatment of the scheme. This is problematic given the number of tunable scheme and code parameters, necessitating time-consuming Monte Carlo simulation. This motivates the novel analytical work of this article, which derives overall error-rate and threshold performances through considering separately the effects of the channel on the coded and uncoded bits. First, new closed-form expressions are derived for the hard-decision performance of the bit mapping of the multi-level modulation scheme, for both coded and uncoded bits. Extrinsic information transfer (EXIT) analysis is then applied to the coded bits in the scheme. The derived theoretical performance of the uncoded bit positions is used in combination with the derived EXIT threshold to provide for the first time for this modulation scheme a method to evaluate analytically whether a designed system will offer capacity-approaching performance. Following this, an approximation to the capacity curve for the coded modulation scheme is produced, again based on the derived analytical performance. Finally, through the relationship between mutual information and error rate performance for error control codes, the derived analytical expressions are used to produce a semi-analytical finite-length performance predictor, whereby error rate results for a given code on the binary input additive white Gaussian noise (AWGN) channel can be mapped to the coded modulation scheme under consideration for any coded system parameters.
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spelling doaj-art-b6bbdb11715f43bd869b52265a9e8fa32025-08-20T02:23:00ZengIEEEIEEE Access2169-35362020-01-01821216621217610.1109/ACCESS.2020.30380829258897LDPC-Coded Modulation Performance Analysis and System DesignCornelius Tomas Healy0https://orcid.org/0000-0001-9409-1625Anas Al Rawi1https://orcid.org/0000-0002-0975-6395Charalampos C. Tsimenidis2https://orcid.org/0000-0003-2247-3397School of Electrical and Electronic Engineering, Newcastle University, Newcastle upon Tyne, U.KResearch and Technology, British Telecom (BT), Ipswich, U.KSchool of Electrical and Electronic Engineering, Newcastle University, Newcastle upon Tyne, U.KIn this work, the low-density parity-check (LDPC)-coded modulation scheme which has been selected for inclusion in the next generation of International Telecommunication Union (ITU) broadband standard is investigated. The multi-level mapping of this scheme offers excellent performance along with a straightforward modulation which is separable into simple one-dimensional schemes. A subset of modulated bit positions are protected by the LDPC code, while the remaining positions benefit from improved Euclidean distance through assignment to distinct constellation regions. To date, there has been a lack of analytical treatment of the scheme. This is problematic given the number of tunable scheme and code parameters, necessitating time-consuming Monte Carlo simulation. This motivates the novel analytical work of this article, which derives overall error-rate and threshold performances through considering separately the effects of the channel on the coded and uncoded bits. First, new closed-form expressions are derived for the hard-decision performance of the bit mapping of the multi-level modulation scheme, for both coded and uncoded bits. Extrinsic information transfer (EXIT) analysis is then applied to the coded bits in the scheme. The derived theoretical performance of the uncoded bit positions is used in combination with the derived EXIT threshold to provide for the first time for this modulation scheme a method to evaluate analytically whether a designed system will offer capacity-approaching performance. Following this, an approximation to the capacity curve for the coded modulation scheme is produced, again based on the derived analytical performance. Finally, through the relationship between mutual information and error rate performance for error control codes, the derived analytical expressions are used to produce a semi-analytical finite-length performance predictor, whereby error rate results for a given code on the binary input additive white Gaussian noise (AWGN) channel can be mapped to the coded modulation scheme under consideration for any coded system parameters.https://ieeexplore.ieee.org/document/9258897/LDPC codescoded modulationEXIT charts
spellingShingle Cornelius Tomas Healy
Anas Al Rawi
Charalampos C. Tsimenidis
LDPC-Coded Modulation Performance Analysis and System Design
IEEE Access
LDPC codes
coded modulation
EXIT charts
title LDPC-Coded Modulation Performance Analysis and System Design
title_full LDPC-Coded Modulation Performance Analysis and System Design
title_fullStr LDPC-Coded Modulation Performance Analysis and System Design
title_full_unstemmed LDPC-Coded Modulation Performance Analysis and System Design
title_short LDPC-Coded Modulation Performance Analysis and System Design
title_sort ldpc coded modulation performance analysis and system design
topic LDPC codes
coded modulation
EXIT charts
url https://ieeexplore.ieee.org/document/9258897/
work_keys_str_mv AT corneliustomashealy ldpccodedmodulationperformanceanalysisandsystemdesign
AT anasalrawi ldpccodedmodulationperformanceanalysisandsystemdesign
AT charalamposctsimenidis ldpccodedmodulationperformanceanalysisandsystemdesign