Improving soft FEC performance for higher-order modulations via optimized bit channel mappings

Häger, Christian; Amat, Alexandre Graell i; Brännström, Fredrik; Alvarado, Alex; Agrell, Erik

doi:10.1364/oe.22.014544

Cited by 21 publications

(25 citation statements)

References 27 publications

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“…Accordingly, in our work, we carry out numerical analysis on a P-LDPC coded RGB-LED-based VLC system by means of the protograph-based extrinsic information transfer (PEXIT) method [19], whose validity has been verified in many prior works such as [20]- [22]. With the aid of the PEXIT tool, we optimize the coded VLC system in three aspects, i.e., the interleaver, the power mixing ratio of RGB lights, and the selection of coding schemes.…”

Section: Introductionmentioning

confidence: 88%

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Analysis and Optimization of P-LDPC Coded RGB-LED-Based VLC Systems

et al. 2015

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The goal of this paper is to study a well-performed coded modulation structure in visible light communication (VLC) systems equipped with red, green, and blue (RGB) light-emitting diodes (LEDs) to provide tools for performance analysis and to give guidelines for practical designs. Specifically, the protograph-based low-density parity-check (P-LDPC) codes and the optimized generalized variable degree matched mapping interleavers are applied to VLC systems for the first time. To theoretically analyze the system under concern, we utilize the protograph-based extrinsic information transfer (PEXIT) methodology that can accurately predict error performance. Furthermore, by leveraging this powerful analysis tool, we propose optimizing a VLC system from three perspectives, i.e., the interleaver design, the optimization of the power mixing ratio of RGB color lights, and the selection of coding schemes. Both PEXIT analyses and simulations verify that the performance of a VLC system can be greatly improved by optimizing these three components.Index Terms: Visible light communication (VLC), Red, green, and blue light-emitting diode (RGB LED), Low-density parity-check (LDPC), Protograph-based extrinsic information transfer (PEXIT).

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Section: Introductionmentioning

confidence: 88%

“…This method is utilized for accurate performance analysis in various scenarios such as fading channels [20], half-duplex relay channels [21], and fiber-optical systems [22]. The calculation procedure of the PEXIT Fig.…”

Section: P-ldpc Codes Gvdmm Structure and Pexitmentioning

confidence: 99%

Analysis and Optimization of P-LDPC Coded RGB-LED-Based VLC Systems

et al. 2015

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“…3 (a) show that for BER pre ≈ 0.2 and 256QAM, the code rate can be increased to R c = 2/5. This shows that the use of the the SD-FEC limit paradigm in this scenario leads to an underestimation of the spectral 9 For M = 256, the use of max-log L-values is very relevant in practice as the calculation in (29) is greatly simplified. efficiency of 20%.…”

Section: A Awgn Channelmentioning

confidence: 99%

“…II-A and four modulation formats: M -QAM constellations with M = 4, 8, 64, 256. For M = 4, 64, the SD decoder uses exact L-values and for M = 8, 256, max-log L-values 9 . In Fig.…”

Section: A Awgn Channelmentioning

confidence: 99%

Replacing the Soft-Decision FEC Limit Paradigm in the Design of Optical Communication Systems

Alvarado

Agrell

Lavery

et al. 2016

J. Lightwave Technol.

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106

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Abstract-The FEC limit paradigm is the prevalent practice for designing optical communication systems to attain a certain bit-error rate (BER) without forward error correction (FEC). This practice assumes that there is an FEC code that will reduce the BER after decoding to the desired level. In this paper, we challenge this practice and show that the concept of a channel-independent FEC limit is invalid for soft-decision bitwise decoding. It is shown that for low code rates and high order modulation formats, the use of the soft FEC limit paradigm can underestimate the spectral efficiencies by up to 20%. A better predictor for the BER after decoding is the generalized mutual information, which is shown to give consistent post-FEC BER predictions across different channel conditions and modulation formats. Extensive optical full-field simulations and experiments are carried out in both the linear and nonlinear transmission regimes to confirm the theoretical analysis.

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“…The P-EXIT analysis is used to predict the asymptotic decoding behavior assuming infinite codeword length for an additive white Gaussian noise (AWGN) channel. For more details about this procedure, we refer the reader to 9 . Once an optimized bit mapping matrix A * is found, the finitelength bit mapper is obtained via the rounded matrix M A * , from which the index assignment of coded bits to modulation bits is determined.…”

Section: Bit Mapper Optimizationmentioning

confidence: 99%