Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

A channel coder design for a high speed and less complex communication system using QC - LDPC codes

Koluguri Sarika, P. P. Deepthi

Published Apr 1, 2014• 2 citations
Publisher

Abstract

Forward error correcting codes are successfully implemented in high speed communication for error-free transmission with high data rate. One such code is Low Density Parity Check (LDPC) code. In this paper, Quasi Cyclic (QC) construction of LDPC code is used and we investigate the performance of various decoding algorithms of QC-LDPC code. Their performances in terms of error correction and complexity are compared. The speed of convergence of various decoding algorithms of LDPC code is analyzed by using the Density Evolution theory. With this thresholding in iterations, the BER performances of different algorithms are simulated. Our results show that the same BER performance can be achieved with reduced number of iterations or the speed of the system can be improved without much sacrifice in BER performance.

DOI
10.1109/iccsp.2014.6949855

Related papers

On the use of QC-LDPC code for data transfer using short and medium block length

Mohammad Rakibul Islam, Jinsang Kim

Quasi Cyclic Low Density Parity Check codes (QC-LDPC) is proposed to reduce the complexity of the Low Density Parity Check codes (LDPC) further while obtaining the similar performance. Our proposed QC-LDPC presents an improved construction of circulant sub-matrices based QC-LDPC at high SNR. The proposed construction yields a performance gain of about 1 dB at a 0.0003 bit error rate (BER). Proposed code is tested on 4 types of decoding algorithm and compared. Proposed algorithm is also compared with the existing QC-LDPC and the proposed approach outperforms the existing one at high SNR. Simulation is also performed varying the number of horizontal submatrix and the result shows that the parity check matrix with smaller horizontal concatenation shows better performance.

International Conference on Advanced Communication Technology•Feb 15, 2009•3 citations

Low-density parity-check code for high-speed fibre-optic communication and its experimental verification

Bo Xu, Jiandong Xie

Although low-density parity-check (LDPC) code has been proved as a powerful forward error correction code for fibre optic communication, its soft-decoding requires high quantisation resolution which is difficult to achieve for high-speed fibre-optic communication systems. A modification to LDPC decoding algorithms is proposed to effectively improve the performance at quantisation resolution as low as two-bit or one-bit. The good decoding performance of LDPC code for error correction is confirmed by experiment. Compared with the RS(255, 239) code commonly used in optical fibre communication, a Q-factor improvement of 2-dB is obtained in the experiment for an LDPC code with quasi-cyclic structure at the same redundancy as the RS code. Furthermore, the impacts of sampling phase and channel estimation using real data over the decoding performance are analysed.

IET Communications•Jun 24, 2010•5 citations

A layered QC-LDPC decoder architecture for high speed communication system

Chiu‐Wing Sham, Xu Chen, Wai M. Tam +2 more

The performance of a high-throughput long-distance communication system such as an optical transmission system is limited by the Net Coding Gain (NCG) of the Forward Error Correction (FEC) system. Summarizing the previous research works, Low-Density Parity-Check (LDPC) codes form one of the most promising FEC schemes to be applied in high-throughput communication systems. Designing a practical channel coding scheme with high code rate, low complexity, high throughput and extremely low error floor has always been a very challenging problem. Quasi-cyclic low-density parity-check (QC-LDPC) codes have been promising candidates to fulfill the above requirements but the implementation issues remain. In this paper, we propose a layered QC-LDPC decoder architecture with high code rate, low complexity, high throughput and excellent error performance. The architecture has been implemented using FPGA and the error performance has been shown to be good.

IEEE Asia Pacific Conference on Circuits and Systems (APCCAS)•Dec 1, 2012•35 citations

The design of structured LDPC codes with algorithmic graph construction

Wojciech Sułek

Low-Density Parity-Check (LDPC) codes are among the most effective modern error-correcting codes due to their excellent correction performance and highly parallel decoding scheme. Moreover, the nonbinary extension of such codes further increases performance in the short-block regime. In this paper, we review the key elements for the construction of implementation-oriented binary and nonbinary codes. These Quasi-Cyclic LDPC (QC-LDPC) codes additionally feature efficient encoder and decoder implementation frameworks. We then present a versatile algorithm for the construction of both binary and nonbinary QC-LDPC codes that have low encoding complexity and an optimized corresponding graph structure. Our algorithm uses a progressive edge growth algorithm, modified for QC-LDPC graph construction, and then performs an iterative global search for optimized cyclic shift values within the QC-LDPC circulants. Strong error correction performance is achieved by minimizing the number of short cycles, and cycles with low external connectivity, within the code graph. We validate this approach via error rate simulations of a transmission system model featuring an LDPC coder-decoder, digital modulation, and additive white Gaussian noise channels. The obtained numerical results validate the effectiveness of the proposed construction algorithm, with a number of constructed codes exhibiting either similar or superior performance to industry standard binary codes and selected nonbinary codes from the literature.

Bulletin of the Polish Academy of Sciences Technical Sciences•May 30, 2022•0 citations

Analysis on QC-LDPC Decoding Algorithms for WLAN Systems

Xin Lu, Zhan Shaobin, Xu Jiong

Next generation wireless systems, such as IEEE802.11n and 802.16e, need high error-correction capacity to achieve high data rate transmission. Therefore, a low-density parity-check code(LDPC code) is adopted as a FEC code. Quasi-cyclic LDPC code(QC-LDPC) code is an important branch of LDPC code research. IEEE 802.16e proposes a parity-check matrix with quasi-cyclic character which makes the encoding very simply. This paper introduces the encoding process and several decoding algorithms for LDPC including Log-BP algorithm, Min-Sum(MS) algorithm and modified MS algorithm. Simulations results under a next generation wireless LAN system show that MS comparing with the Log-BP performance has approximately 0.5dB loss for high-speed rates codes over AWGN channel, however the performance of normalized MS and row weight matched MS with relatively low complexity is nearly the same as that of Log-BP algorithm.

International Conference on Intelligent Computation Technology and Automation•May 1, 2010•2 citations

Performance Analysis of NB-QC-LDPC Code for High-Speed Optical Communication Systems

Zhiqiang Lin, Jianyong Zhang

In the paper, we construct the non-binary quasi-cyclic low-density parity check (NB-QC-LDPC) code from the quasi-cyclic low-density parity check (QC-LDPC) code. The NB-QC-LDPC code over the Galois field GF(4) is suitable for 100Gb/s optical communication systems with QPSK or DQPSK modulation formats. We also study the bit error ratio (BER) performance of the NB-QC-LDPC code by using the Log-Fourier Sum and Product decoding algorithm (LFSPA). The numerical results show that the NB-QC-LDPC code with code length 500 can provide approximately 5.5dB coding gain at the BER of 910- and outperform QC-LDPC code by 0.7dB.

International Conference on Electronics, Communications and Control•Oct 16, 2012•0 citations
Forward error correcting codes are successfully implemented in high speed communication for error-free transmission with high data rate. One such code is Low Density Parity Check (LDPC) code. In this paper, Quasi Cyclic (QC) construction of LDPC code is used and we investigate the performance of various decoding algorithms of QC-LDPC code. Their performances in terms of error correction and complexity are compared. The speed of convergence of various decoding algorithms of LDPC code is analyzed by using the Density Evolution theory. With this thresholding in iterations, the BER performances of different algorithms are simulated. Our results show that the same BER performance can be achieved with reduced number of iterations or the speed of the system can be improved without much sacrifice in BER performance.
Quasi Cyclic Low Density Parity Check codes (QC-LDPC) is proposed to reduce the complexity of the Low Density Parity Check codes (LDPC) further while obtaining the similar performance. Our proposed QC-LDPC presents an improved construction of circulant sub-matrices based QC-LDPC at high SNR. The proposed construction yields a performance gain of about 1 dB at a 0.0003 bit error rate (BER). Proposed code is tested on 4 types of decoding algorithm and compared. Proposed algorithm is also compared with the existing QC-LDPC and the proposed approach outperforms the existing one at high SNR. Simulation is also performed varying the number of horizontal submatrix and the result shows that the parity check matrix with smaller horizontal concatenation shows better performance.
Although low-density parity-check (LDPC) code has been proved as a powerful forward error correction code for fibre optic communication, its soft-decoding requires high quantisation resolution which is difficult to achieve for high-speed fibre-optic communication systems. A modification to LDPC decoding algorithms is proposed to effectively improve the performance at quantisation resolution as low as two-bit or one-bit. The good decoding performance of LDPC code for error correction is confirmed by experiment. Compared with the RS(255, 239) code commonly used in optical fibre communication, a Q-factor improvement of 2-dB is obtained in the experiment for an LDPC code with quasi-cyclic structure at the same redundancy as the RS code. Furthermore, the impacts of sampling phase and channel estimation using real data over the decoding performance are analysed.
The performance of a high-throughput long-distance communication system such as an optical transmission system is limited by the Net Coding Gain (NCG) of the Forward Error Correction (FEC) system. Summarizing the previous research works, Low-Density Parity-Check (LDPC) codes form one of the most promising FEC schemes to be applied in high-throughput communication systems. Designing a practical channel coding scheme with high code rate, low complexity, high throughput and extremely low error floor has always been a very challenging problem. Quasi-cyclic low-density parity-check (QC-LDPC) codes have been promising candidates to fulfill the above requirements but the implementation issues remain. In this paper, we propose a layered QC-LDPC decoder architecture with high code rate, low complexity, high throughput and excellent error performance. The architecture has been implemented using FPGA and the error performance has been shown to be good.
Low-Density Parity-Check (LDPC) codes are among the most effective modern error-correcting codes due to their excellent correction performance and highly parallel decoding scheme. Moreover, the nonbinary extension of such codes further increases performance in the short-block regime. In this paper, we review the key elements for the construction of implementation-oriented binary and nonbinary codes. These Quasi-Cyclic LDPC (QC-LDPC) codes additionally feature efficient encoder and decoder implementation frameworks. We then present a versatile algorithm for the construction of both binary and nonbinary QC-LDPC codes that have low encoding complexity and an optimized corresponding graph structure. Our algorithm uses a progressive edge growth algorithm, modified for QC-LDPC graph construction, and then performs an iterative global search for optimized cyclic shift values within the QC-LDPC circulants. Strong error correction performance is achieved by minimizing the number of short cycles, and cycles with low external connectivity, within the code graph. We validate this approach via error rate simulations of a transmission system model featuring an LDPC coder-decoder, digital modulation, and additive white Gaussian noise channels. The obtained numerical results validate the effectiveness of the proposed construction algorithm, with a number of constructed codes exhibiting either similar or superior performance to industry standard binary codes and selected nonbinary codes from the literature.
Next generation wireless systems, such as IEEE802.11n and 802.16e, need high error-correction capacity to achieve high data rate transmission. Therefore, a low-density parity-check code(LDPC code) is adopted as a FEC code. Quasi-cyclic LDPC code(QC-LDPC) code is an important branch of LDPC code research. IEEE 802.16e proposes a parity-check matrix with quasi-cyclic character which makes the encoding very simply. This paper introduces the encoding process and several decoding algorithms for LDPC including Log-BP algorithm, Min-Sum(MS) algorithm and modified MS algorithm. Simulations results under a next generation wireless LAN system show that MS comparing with the Log-BP performance has approximately 0.5dB loss for high-speed rates codes over AWGN channel, however the performance of normalized MS and row weight matched MS with relatively low complexity is nearly the same as that of Log-BP algorithm.
In the paper, we construct the non-binary quasi-cyclic low-density parity check (NB-QC-LDPC) code from the quasi-cyclic low-density parity check (QC-LDPC) code. The NB-QC-LDPC code over the Galois field GF(4) is suitable for 100Gb/s optical communication systems with QPSK or DQPSK modulation formats. We also study the bit error ratio (BER) performance of the NB-QC-LDPC code by using the Log-Fourier Sum and Product decoding algorithm (LFSPA). The numerical results show that the NB-QC-LDPC code with code length 500 can provide approximately 5.5dB coding gain at the BER of 910- and outperform QC-LDPC code by 0.7dB.