• Journal of Satellite, Information and Communications
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• v.10 no.3
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• pp.73-77
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• 2015

In this paper, we present two simulation methods to investigate the effect of excluding bit errors on generating the extrinsic information transfer (EXIT) chart for low density parity check (LDPC) and turbo codes. We utilized the simulation methods including and excluding bit errors to generate EXIT chart which was originally proposed for turbo codes. The generated EXIT charts for LDPC and turbo codes shows that the presented methods appropriately demonstrates the performance behaviours of iterative decoding for LDPC and turbo codes. Analysis on the simulation results demonstrates that the EXIT chart excluding the bit errors shows only a small part of the curves where the amount of information is too large.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.7C
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• pp.587-593
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• 2010

In this paper we design an irregular low-density parity-check (LDPC) code for multiple-input multiple-output (MIMO) system, using a simple extrinsic information transfer (EXIT) chart method. The MIMO systems considered are optimal maximum a posteriori probability (MAP) detector. The MIMO detector and the LDPC decoder exchange soft information and form a turbo iterative receiver. The EXIT charts are used to obtain the edge degree distribution of the irregular LDPC code which is optimized for the MIMO detector. It is shown that the performance of the designed LDPC code is better than that of conventional LDPC code which was optimized for either the Additive White Gaussian Noise (AWGN) channel or the MIMO channel.

• Proceedings of the IEEK Conference
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• 2006.06a
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• pp.1049-1050
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• 2006

In this paper, we present the analysis of Tree-LDPC codes using EXIT(Extrinsic information transfer) charts methods. Two different EXIT charts schemes are compared. One is based on the closed form equation and the other is based on Monte-Carlo simulation. The thresholds by these two schemes match well with the threshold by DE(density evolution) scheme. Simulation performance is also shown with the obtained thresholds.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.9C
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• pp.841-847
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• 2009

In this paper we propose a high-performance Hybrid ARQ scheme employing Chase combining based on LDPC (Low-Density Parity-Check) codes. The proposed scheme uses symbol mapping diversity and turbo demodulation to improve decoding performance. We analyze the performance of the proposed scheme by EXIT (EXtrinsic Information Transfer) chart and compare its performance with several symbol mappings.

• Information and Communications Magazine
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• v.24 no.12
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• pp.14-21
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• 2007

This paper aims to improve the design of iterative detection and decoding(IDD) based on the soft interference cancellation with minimum mean squared error(SC-MMSE) detector, which shows low performance compared to the maximum a posteriori(MAP) detector. By means of extrinsic information transfer(EXIT) chart analysis, such low performance may be attributed to that the "pure"(original) turbo principle is not always best for IDD. Thus, we propose a new IDD architecture based on the SC-MMSE detector which uses new a priori information. Simulation results show that the performance of the proposed IDD is very close to that of IDD based on the MAP detector.

• Journal of Communications and Networks
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• v.16 no.3
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• pp.249-257
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• 2014

This paper presents methods to the construction of regular and irregular low-density parity-check (LDPC) codes based on Euclidean geometries over the Galois field. Codes constructed by these methods have quasi-cyclic (QC) structure and large girth. By decomposing hyperplanes in Euclidean geometry, the proposed irregular LDPC codes have flexible column/row weights. Therefore, the degree distributions of proposed irregular LDPC codes can be optimized by technologies like the curve fitting in the extrinsic information transfer (EXIT) charts. Simulation results show that the proposed codes perform very well with an iterative decoding over the AWGN channel.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.11 no.4
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• pp.1954-1971
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• 2017

In this work, first, a multiuser detection (MUD) algorithm based on component-level soft interference cancellation and linear minimum mean square error (CLSIC-LMMSE) is proposed, which can enhance the bit error ratio (BER) performance of the traditional SIC-LMMSE-based MUD by mitigating error propagation. Second, for non-binary low density parity check (NB-LDPC) coded high-order modulation systems, when the proposed algorithm is integrated with partial mapping, the receiver with iterative detection and decoding (IDD) achieves not only better BER performance but also significantly computational complexity reduction over the traditional SIC-LMMSE-based IDD scheme. Extrinsic information transfer chart (EXIT) analysis and numerical simulations are both used to support the conclusions.

• Proceedings of the IEEK Conference
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• 2008.06a
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• pp.161-162
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• 2008

In this paper we design an irregular low-density parity-check (LDPC) code for a multi-input multi-output (MIMO) system. The considered MIMO system is minimum mean square error soft-interference cancellation (MMSE-SIC) detector. The MMSE-SIC detector and the LDPC decoder exchange soft information and consist a turbo iterative detection and decoding receiver. Extrinsic information transfer (EXIT) charts are used to obtain the edge degree distribution of the irregular LDPC code which is optimized for the input-output transfer chart of the MMSE-SIC detector. It is shown that the performance of the designed LDPC code is much better than that of conventional LDPC code optimized for the AWGN channel.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.14 no.7
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• pp.567-574
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• 2002

In the present study, ventilation flow rates and pressure rises through a road tunnel are simulated numerically using CFD with the various conditions such as roughness height, swirl angle of jet fan, entrance and exit effect and hub to tip ratio. By using a modified wall function, friction factor can be predicted under 10％ of error with respect to the Moody chart for the circular pipe flow and 15％, for the present tunnel. For more precise design, the effects of the swirl angle and hub to tip ratio of jet fan, which is not included in the theoretical equation of pressure rise by jet fan are necessary to be considered.

• International Journal of Air-Conditioning and Refrigeration
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• v.11 no.4
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• pp.178-187
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• 2003

In this study, ventilation flow rate and pressure rise through a tunnel are simulated numerically using computational fluid dynamics (CFD) for various conditions such as roughness height of the surface of tunnel, swirl angle and hub/tip ratio of jet fan, and entrance and exit effects. By using a modified wall function, friction factor can be predicted with respect to the Moody chart within 10% of error for the circular pipe flow and 15% for the present tunnel. For more accurate design, the effect of the swirl angle and hub/tip ratio of jet fan, which is not included in the theoretical equation of pressure rise by jet fan needs to be considered.