Toggle Main Menu Toggle Search

Open Access padlockePrints

LDPC-Coded Modulation Performance Analysis and System Design

Lookup NU author(s): Dr Cornelius Healy, Professor Harris Tsimenidis



This work is licensed under a Creative Commons Attribution 4.0 International License (CC BY 4.0).


© 2013 IEEE.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.

Publication metadata

Author(s): Healy CT, Rawi AA, Tsimenidis CC

Publication type: Article

Publication status: Published

Journal: IEEE Access

Year: 2020

Volume: 8

Pages: 212166-212176

Online publication date: 16/11/2020

Acceptance date: 02/04/2016

Date deposited: 25/01/2021

ISSN (electronic): 2169-3536

Publisher: Institute of Electrical and Electronics Engineers Inc.


DOI: 10.1109/ACCESS.2020.3038082


Altmetrics provided by Altmetric


Funder referenceFunder name