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Proceedings ArticleDOI

Performance scrutiny and optimization of LDPC coded MIMO OFDM systems

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TLDR
Performance analysis and design optimization of LDPC coded multiple input multiple output (MIMO) orthogonal frequency division multiplexing (OFDM) has been considered and small block-size irregular codes for outage MIMO-OFDM channels are constructed.
Abstract
The implementable decoders and large collection of data transmission and storage channels can be admitted at the same time using low density parity check (LDPC) group of Linear block codes. We will review some of the LDPC construction techniques and encoding problem for LDPC codes. Also certain special classes of LDPC codes which will resolve encoding problems will be introduced. Performance analysis and design optimization of LDPC coded multiple input multiple output(MIMO) orthogonal frequency division multiplexing(OFDM) has been considered. The tools of density evolution with mixture Gaussian approximations are used to optimize LDPC codes which are not regular and to compute minimum operational signal-to-noise ratios (SNRs) for ergodic MIMO-OFDM channels. In particular, the optimization is done for various MIMO-OFDM system configurations, which include a different channel models and different demodulation schemes; the performance which is optimized is checked with the corresponding channel capacity. The iterative message passing decoding algorithm which gives optimal performance will be presented. The performance of turbo-iterative receiver that consists of a soft maximum a posteriori (MAP) demodulator will be presented. From the LDPC profiles that already are optimized for ergodic channels, we construct small block-size irregular codes for outage MIMO-OFDM channels.

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Proceedings ArticleDOI

Performance Enhancement of IDMA System by Power and LDPC Code Optimization

Jingxi Zhang
TL;DR: A novel way is presented to improve the performance of system in multiple access channel (MAC) by means of power allocation and low-density parity-check codes (LDPC) design and Gaussian approximation method is used as a tool to approximate message the probability density function (PDF) and message updating formulas are derived.
References
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Book

Low-Density Parity-Check Codes

TL;DR: A simple but nonoptimum decoding scheme operating directly from the channel a posteriori probabilities is described and the probability of error using this decoder on a binary symmetric channel is shown to decrease at least exponentially with a root of the block length.
Book

Information Theory, Inference and Learning Algorithms

TL;DR: A fun and exciting textbook on the mathematics underpinning the most dynamic areas of modern science and engineering.
Journal ArticleDOI

Design of capacity-approaching irregular low-density parity-check codes

TL;DR: This work designs low-density parity-check codes that perform at rates extremely close to the Shannon capacity and proves a stability condition which implies an upper bound on the fraction of errors that a belief-propagation decoder can correct when applied to a code induced from a bipartite graph with a given degree distribution.
Proceedings ArticleDOI

Efficient implementations of the sum-product algorithm for decoding LDPC codes

TL;DR: By exploiting the inherent robustness of LLRs, it is shown, via simulations, that coarse quantization tables are sufficient to implement complex core operations with negligible or no loss in performance.
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