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Low-Complexity soft-Decision Detection for Combating DFE Burst Errors in IM/DD Links

JOURNAL OF LIGHTWAVE TECHNOLOGY 2024年第5期42卷 1395-1408页

作者： Wu, Kaiquan Liga, Gabriele Riani, Jamal Alvarado, Alex Eindhoven Univ Technol Dept Elect Engn Informat & Commun Theory Lab Signal Proc Syst Grp NL-5600 MB Eindhoven Netherlands Marvell Technol Santa Clara CA 95054 USA

The deployment of non-binary pulse amplitude modulation (PAM) and soft decision (SD)-forward error correction (FEC) in future intensity-modulation (IM)/direct-detection (DD) links is inevitable. However, high-speed IM/DD links suffer from inter-symbol interference (ISI) due to bandwidth-limited hardware. Traditional approaches to mitigate the effects of ISI are filters and trellis-based algorithms targeting symbol-wise maximum a posteriori (MAP) detection. The former approach includes decision-feedback equalizer (DFE), and the latter includes Max-Log-MAP (MLM) and soft-output viterbi algorithm (SOVA). Although DFE is easy to implement, it introduces error propagation (EP). Such burst errors distort the log-likelihood ratios (LLRs) required by SD-FEC, causing performance degradation. On the other hand, MLM and SOVA provide near-optimum performance, but their complexity is very high for high-order PAM. In this article, we consider a one-tap partial response channel model, which is relevant for high-speed IM/DD links. We propose to combine DFE with either MLM or SOVA in a low-complexity architecture. The key idea is to allow MLM or SOVA to detect only 3 typical DFE symbol errors, and use the detected error information to generate LLRs in a modified demapper. The proposed structure enables a tradeoff between complexity and performance: i) the complexity of MLM or SOVA is reduced and ii) the decoding penalty due to EP is mitigated. Compared to SOVA detection, the proposed scheme can achieve a significant complexity reduction of up to 94% for PAM-8 transmission. Simulation and experimental results show that the resulting SNR loss is roughly $0.3\!\sim\! 0.4$ dB for PAM-4, and becomes marginal 0.18 dB for PAM-8.

关键词： Direct detection decision-feedback equalizer intensity modulation MAP algorithm pulse amplitude modulation soft-decision decoding soft-output viterbi algorithm

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Joint source and channel decoding of compressed still images

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SIGNAL PROCESSING-IMAGE COMMUNICATION 1999年第3期15卷 217-229页

作者： Xu, W Hagenauer, J Hollmann, J Tech Univ Munich Lehrstuhl Nachrichtentech D-80290 Munich Germany

A joins source-channel decoding approach is described, which utilizes the residual redundancy in the bit stream of a source-coded image by employing a modified APRI-SOVA (a priori soft-output viterbi algorithm) at the channel decoder. The source coders used are the nonadaptive discrete cosine transform (]DCT) coding and subband coding with Lloyd-Max quantization. The log-likelihood ratio describing the a priori information is linearized. The reliability of the current bit is computed as a proper linear combination of the soft values characterizing statistical dependency of the zeroth order (probability of 1's or 0's) and the first order (bit correlation among neighboring samples). Substantial subjective and objective performance gains can be obtained by using this method. It is demonstrated that especially in a noisy environment, it may be better to keep the residual redundancy in the data and use it at the receiver side in order to achieve a more reliable decoding, rather than to further remove it by using a variable length coding. The trade-off between the allocation of bits for source and channel coding is also addressed. (C) 1999 Elsevier Science B.V. All rights reserved.

关键词： joint source-channel coding DCT coding subband coding soft-output viterbi algorithm

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Weighted interference cancellation detector for convolutionally coded CDMA system

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ELECTRONICS LETTERS 1999年第19期35卷 1617-1618页

作者： Joo, WY Yoon, SY Lee, HS Korea Adv Inst Sci & Technol Dept Elect Engn Taejon 305701 South Korea Samsung Elect Co Ltd Telecommun R&D Ctr Seoul South Korea SK Telecom Cent R&D Lab Seoul South Korea

Weighted interference cancellation is proposed to improve the post-decoding interference cancellation detector in a convolutionally coded CDMA system. A weight determination method is presented in which the estimated information bit error probability from the soft-output viterbi algorithm is used. Simulation results show that the proposed scheme outperforms the previous post-decoding interference cancellation detector.

关键词： interference suppression viterbi decoding weighted interference cancellation detector convolutionally coded CDMA system soft-output viterbi algorithm Electromagnetic compatibility and interference Codes post-decoding interference cancellation weight determination method convolutional codes information bit error probability code division multiple access Multiple access communication

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Combined concatenated coding and nonlinear equalization for magnetic recording channels

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IEEE TRANSACTIONS ON MAGNETICS 2002年第5期38卷 2298-2300页

作者： Ghrayeb, A Amer Univ Sharjah Dept Elect & Comp Engn Aharjah U Arab Emirates

In this paper, we combine concatenated coding (with iterative decoding) and equalization for nonlinear magnetic recording channels. We modify the iterative soft-output viterbi algorithm to incorporate a nonlinear equalizer capable of removing both precursor and postcursor (nonlinear) ISI. We adopt a simple partial erasure model against which we examine the proposed algorithm for parallel and serial concatenated codes where code rate 16/17 is considered. We demonstrate, via simulations, that improvements of about 2.5 dB at a bit-error rate of 10(-6) are possible.

关键词： coneatenated coding magnetic recording nonlinear equalization partial erasure soft-output viterbi algorithm

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Signal Detection Under Multipath Intersymbol Interference in Staggered Bit-Patterned Media Recording Systems

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IEEE MAGNETICS LETTERS 2019年 10卷 1-5页

作者： Jeong, Seongkwon Lee, Jaejin Soongsil Univ Dept CMC Convergence Technol Seoul 156743 South Korea

Bit-patterned media recording was invented with the aim of achieving high areal density. However, bit-patterned media recording suffers from two-dimensional (2-D) interference problems, including intersymbol interference in the down-track direction and intertrack interference in the cross-track direction. The 2-D interference corrupts the readback signal and degrades the performance of bit-patterned media recording. Unlike the layout of regular-array bit-patterned media, in the layout of staggered-array bit-patterned media, islands along neighboring tracks are displaced by a half-period from islands on the main data track;hence, in terms of intertrack interference, the islands on the main data track are predominantly affected by the closest four islands on neighboring tracks. To address this problem, a proper signal detection scheme for staggered bit-patterned media recording should be developed. In this letter, we introduce a multipath soft-output viterbi algorithm for reducing the 2-D interference in staggered bit-patterned media recording. We investigate different partial response targets and compare the performances of the one-dimensional, two-dimensional, and proposed three-path soft-output viterbi algorithm.

关键词： Information storage bit-patterned media recording intersymbol interference partial response maximum likelihood soft-output viterbi algorithm

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Combined concatenated coding and nonlinear equalization for magnetic recording channels

Combined concatenated coding and nonlinear equalization for ...

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International Magnetics Conference (Intermag Europe 2002)

作者： Ghrayeb, A Amer Univ Sharjah Dept Elect & Comp Engn Aharjah U Arab Emirates

ISBN: (纸本)0780373650

关键词： coneatenated coding magnetic recording nonlinear equalization partial erasure soft-output viterbi algorithm

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A new reduced complexity turbo-detector for highly selective long delay spread ISI channels: A solution for 4G mobile systems?

A new reduced complexity turbo-detector for highly selective...

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53rd IEEE Vehicular Technology Conference (VTC)

作者： Berthet, AO Penther, B Visoz, R Boutros, JJ Alcatel Space Ind F-92734 Nanterre France

ISBN: (纸本)0780367286

In this paper, we investigate a new turbo-detector scheme. The data detection part of the iterative receiver is based on variants of full-states SOVE and SOVA Interference InterSymbols (ISI) decoders. Those variants employ reduced-state techniques combined with generalized per-survivor processing. They offer a very good trade-off between performance and complexity even with long delay channels. Monte-Carlo simulation results in various severe propagation environments show that the proposed sub-optimal turbo-detector is usually 1,8 to 3 dB away from the optimal BCJR-based one with a significant computational complexity reduction. Hence it appears as a possible candidate for future mobile radio communications with high bit rate transmission.

关键词： turbo-detection generalized per-survivor processing soft-output viterbi algorithm

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New Concept of PLC Modems: Multi-Carrier System for Frequency Selective Slow-Fading Channels Based on Layered SCCC Turbocodes

New Concept of PLC Modems: Multi-Carrier System for Frequenc...

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作者： Zavrtalek, J. Brno University of Technology

The article introduces a novel concept of a PLC modem as a complement to the existing G3 and PRIME standards for communications using medium- or high-voltage overhead or cable lines. The proposed concept is based on the fact that the levels of impulse noise and frequency selectivity are lower on high-voltage lines than on low-voltage ones. Also, the demands for “cost-effective” circuitry design are not so crucial as in the case of modems for low-voltage level. In contract to these positive conditions, however, there is the need to overcome much longer distances and to take into account low SNR on the receiving side. With respect to the listed reasons, our concept makes use of MCM, instead of OFDM. The assumption of low SNR is compensated through the use of an efficient channel coding based on a serially concatenated turbo code. In addition, MCM offers lower latency and PAPR compared to OFDM. Therefore, when using MCM, it is possible to excite the line with higher power. The proposed concept has been verified during experimental transmission of testing data over a real, 5 km long, 22kV overhead line.

关键词： Power line communication multi-carrier modulation serially concatenated convolutional codes Iterative detection BCJR forward-backward algorithm soft-output viterbi algorithm soft-in soft-out module expectation-maximization algorithm soft decision

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One-Dimensional Serial Detection Using New Two-Dimensional Partial Response Target Modeling for Bit-Patterned Media Recording

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IEEE MAGNETICS LETTERS 2020年 11卷 1页

作者： Nguyen, Thien An Lee, Jaejin Soongsil Univ Dept Informat Commun Convergence Technol Seoul 06978 South Korea

Bit-patterned media recording (BPMR) is a candidate technology that extends the density to up to 4 Tb/in(2) to handle large amounts of data. However, in BPMR systems, the major challenge is two-dimensional (2-D) interference, which includes intersymbol interference from the down-track direction and intertrack interference from the across-track direction. To combat 2-D interference, it is natural to consider a 2-D viterbi detection scheme. Since the complexity of pure 2-D viterbi detection is quite high, we propose a series of two 1-D viterbi detectors, which is based on new 2-D partial response (PR) target modeling for the BPMR channel. The use of new 2-D PR target model and the two serial 1-D viterbi detection scheme ensures that the complexity is greatly reduced compared to 2-D viterbi detection and the bit error rate performance is improved.

关键词： Information storage bit-patterned media recording intersymbol interference partial response maximum likelihood soft-output viterbi algorithm

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