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Optimization of the Non-Linearity Tolerant 4D Geometric Shaped Constellations for Optical Fiber Communication Systems Using Neural Networks

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JOURNAL OF LIGHTWAVE TECHNOLOGY 2024年第2期42卷 670-680页

作者： Soleimanzade, Amirhosein Ardakani, Masoud Ebrahimzad, Hamid Univ Alberta Dept Elect & Comp Engn Edmonton AB T6G 2R3 Canada Huawei Technol Canada Co Ltd Ottawa ON N2L 0A4 Canada

We propose a novel 4D geometric shaping (GS) method based on multilevel coding (MLC) for optical fiber communication systems that mitigates fiber non-linearity. To design non-linearity tolerant 4D constellations, non-linear interference noise (NLIN) and modulation dependency behavior of the fiber are considered during the optimization process. By doing so, the complexity of the 4D GS problem increases extremely, requiring novel optimization approaches to tackle this challenge. Hence, we build a novel deep neural network structure that can efficiently optimize the position of the 4D points. Moreover, we show that optimizing the geometry based on the well-known generalized mutual information rate is not efficient and results in a significant gap to the mutual information rate. To solve this issue, we take advantage of the concept of achievable information rates (AIRs) and multilevel coding. By optimizing the 4D constellations based on the proposed AIRs, our GS scheme provides higher rates than the traditional probabilistic shaping and the recent non-linearity tolerant GS methods.

关键词： 4D geometric shaping achievable information rate multilevel coding neural network-based optimization non-linear fiber channel optical fiber communication

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Adaptive Generator Sequence Selection in multilevel Space-Time Trellis Codes

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WIRELESS PERSONAL COMMUNICATIONS 2014年第4期75卷 1851-1862页

作者： Jain, Dharmvir Sharma, Sanjay Thapar Univ Dept Elect & Commun Engn Patiala Punjab India

It has been shown that multilevel space-time trellis codes (MLSTTCs) designed by combining multilevel coding (MLC) with space-time trellis codes (STTCs) can provide improvement in diversity gain and coding gain of the STTCs. MLSTTCs assume perfect channel state information (CSI) at receiver and no knowledge of CSI at transmitter. Weighted multilevel space-time trellis codes (WMLSTTCs), designed by combining MLSTTCs and perfect CSI at transmitter are capable of providing improvement in coding gain of MLSTTCs. In this paper, we present improvement in performance of MLSTTCs by using channel feedback information from the receiver for adaptive selection of generator sequences. The selected generator sequences are used for encoding the component STTCs. The receiver compares current channel profile at receiver with a set of predetermined channel profiles, and sends an index of a predefined channel profile closest to the current channel profile to the transmitter. The transmitter selects a code set that matches best with the current channel profile at receiver using the index. The selected code set having different sets of generator sequences is used by STTC encoders to generate dynamic space-time trellis codes (DSTTCs). The DSTTCs act as component codes in multilevel coding for generating new codes henceforth referred to as multilevel dynamic space-time trellis codes (MLDSTTCs). Analysis and simulation results show that MLDSTTCs provide improvement in performance over MLSTTCs.

关键词： multilevel coding Space-time trellis code Channel state information Rayleigh fading channel Adaptive generator sequences selection

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multilevel LDPC-Coded High-Speed Optical Systems: Efficient Hard Decoding and Code Optimization

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IEEE JOURNAL OF SELECTED TOPICS IN QUANTUM ELECTRONICS 2010年第5期16卷 1268-1279页

作者： Gong, Chen Wang, Xiaodong Columbia Univ Dept Elect Engn New York NY 10027 USA

We consider a multilevel coding scheme employing low-density parity-check (LDPC) codes and high-order modulations for high-speed optical transmissions, where the coherent receiver performs either parallel independent decoding (PID) or multistage decoding (MSD). To meet the severe complexity constraint imposed by the ultrahigh data rate of the emerging optical transmission systems, we focus on hard-decision decoding of LDPC codes. A new LDPC hard decoding method is developed, which is equivalent to the Gallager decoding algorithm B, but is more efficient in terms of circuit implementation, since no variable node degree information is needed. Two variants of this decoder is also proposed, which offers significant performance gain for finite-length codes. We optimize the system by allocating rates and designing profiles for component codes. Both numerical evaluations and simulation results show that the optimized multilevel coding systems with either PID or MSD substantially outperform the optimized single-level LDPC-coded system.

关键词： Code optimization hard-decision decoding low-density parity-check (LDPC) codes multilevel coding optical communications

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Blind equalization of multilevel turbo coded-continuous phase frequency shift keying over MIMO channels

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INTERNATIONAL JOURNAL OF COMMUNICATION SYSTEMS 2007年第1期20卷 103-119页

作者： Osman, Onur Istanbul Commerce Univ TR-34378 Istanbul Turkey

In this paper, multilevel turbo coded-continuous phase frequency shift keying (MLTC-CPFSK) is introduced and its bit error performance in multiple input multiple output (MIMO) facling channels are investigated considering a blind maximum likelihood channel estimation. multilevel turbo coded signals with continuous phase modulation (CPM) provides low spectral occupancy and is Suitable for power and bandwidth-limited channels. Besides, antenna diversity is one of the best method to combat with multipath fading effects. The performance of 2LTC for 4-ary CPFSK over AWGN, Rician (for Rician channel parameter K = 10 dB) and Rayleigh channels are given for 1Tx-1 Rx, 2Tx-1 Rx and 2Tx-2Rx antenna configurations. Channel capacities of 2LTC- 4CPFSK signals are obtained as -5.26, -7.65 and -7.14dB for ITx-1 Rx, 2Tx-1 Rx and 2Tx-2Rx antenna configurations, respectively. Baum-Welch (BW) algorithm is used to estimate the channel parameters. Bit error probabilities of 2 level turbo coded 4 CPFSK (2LTC-4CPFSK) are drawn in the cases of no channel state information (CSI), BW estimation, and perfect CSI. Approximately 0.1 and 0.75 dB gains in E.,INO are obtained using BW channel estimator for Rician and Rayleigh channels, respectively. Therefore, MLTC-CPFSK with BW channel estimator has excellent performance in MIMO fading channels. Copyright (c) 2006 John Wiley & Sons, Ltd.

关键词： multilevel coding turbo codingiblind channel estimation continuous phase inodulation MIMO channels channel capacity

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Generalised concatenation of encoded Gaussian filtered continuous phase modulation

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IEE PROCEEDINGS-COMMUNICATIONS 2000年第4期147卷 205-210页

作者： Bossert, M Shavgulidze, S Häutle, A Dieterich, H Univ Ulm Dept Informat Technol D-89081 Ulm Germany Georgian Tech Univ Dept Digital Commun Theory GE-380075 Tbilisi Georgia

The authors introduce the construction of generalised concatenated (multilevel) encoded Gaussian filtered CPM systems. It is shown that the constructed multilevel codes may operate with coherent and noncoherent demodulation of signals and can be used in Gaussian and Rayleigh-fading channels. The simulation results are presented for both channel types. It is shown that the proposed systems have error performance advantages over the known constructions taken from the literature.

关键词： channel type Critical path method multilevel coding phase modulation continuous phase modulation Gauss signals Simulation results Demodulation

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Coded modulation for noncoherent reception with application to OFDM

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IEEE TRANSACTIONS ON VEHICULAR TECHNOLOGY 2001年第4期50卷 910-919页

作者： Fischer, RFH Lampe, LHJ Müller-Weinfurtner, SH Univ Erlangen Nurnberg Lab Nachrichtentech D-91058 Erlangen Germany AT&T Labs Res Middletown NJ 07748 USA

Power- and bandwidth-efficient differentially encoded transmission over slowly time-varying fading channels with noncoherent reception and without channel state information is considered. For high bandwidth efficiencies, combined phase and amplitude modulation is used. For increased power efficiency, channel coding and multiple-symbol differential detection are applied, i.e., interleaving and detection are based on blocks of N > 2 consecutive symbols. The presented concepts are directly applicable to transmission over flat fading channels. However, concentrating on the situation of frequency-selective channels, we consider their application to multicarrier transmission using orthogonal frequency-division multiplexing (OFDM). When coding across subcarriers, OFDM transforms the actual frequency-selective channel into a slowly time-varying frequency-nonselective fading channel. This paper presents a design for multilevel coding schemes to approach theoretical limits for power- and bandwidth-efficient noncoherent transmission over the equivalent fading channel. It is shown that bit-interleaved coded modulation, which relies on Gray labeling, is competitive only in the case of conventional differential detection with N = 2. The theoretic considerations are well approved by simulation results, where turbo codes are applied as component codes.

关键词： bit-interleaved coded modulation differential encoding multilevel coding noncoherent reception orthogonal frequency-division multiplexing (OFDM)

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Experimental Demonstration of Rate-Adaptive Concatenated Codes for Flexible Optical Networks

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IEEE PHOTONICS TECHNOLOGY LETTERS 2021年第24期33卷 1447-1450页

作者： Mehmood, Tayyab Yankov, Metodi P. Hansen, Henrik E. Forchhammer, Soren Tech Univ Denmark Dept Photon Engn DK-2800 Lyngby Denmark

We experimentally demonstrate a rate-adaptive concatenated forward error correction (FEC) scheme to minimize the information rate loss due to varying channel conditions. The concatenated coding scheme is based on inner soft-decision polar code and outer hard-decision staircase code. An experiment in a wavelength-division multiplexed (WDM) system with different SNR per WDM channel is performed by employing concatenated codes with various coded modulation schemes over a target distance of 140km which is relevant for extending the reach of data center interconnects. Experimental results show that the achieved data rate of the WDM system can be improved up to 37.6% with the proposed coding scheme w.r.t. the fixed code rate ZR FEC.

关键词： Codes Forward error correction Decoding Wavelength division multiplexing Encoding Complexity theory Signal to noise ratio Polar codes staircase codes multilevel coding rate flexibility 400ZR FEC coherent transceivers data center interconnects

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multilevel generalised low-density parity-check codes

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ELECTRONICS LETTERS 2006年第3期42卷 167-168页

作者： Tee, RYS Kuo, FC Hanzo, L Univ Southampton Dept Elect & Comp Sci Southampton SO17 1BJ Hants England

multilevel coding invoking generalised low-density parity-check component codes is proposed, which is capable of outperforming the classic low-density parity check component codes at a reduced decoding latency.

关键词： decoding parity check codes SNR improvement decoding latency generalizedlow-density parity-check codes multilevel coding

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Efficient LLR estimation for multistage decoding

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ELECTRONICS LETTERS 2015年第14期51卷 1076-1077页

作者： Al Bechlawi, C. Guilloud, F. Telecom Bretagne Brest France

multilevel coding (MLC) provides a low-complexity encoding scheme for lattices obtained via construction D. On the other hand, multistage decoding is also a practical decoding scheme for MLC provided that the underlying error correcting codes are capacity achieving, which requires using a powerful soft decoder for each code. Proposed is an approximation of the log-likelihood ratio (LLR) which used for the soft decoding of the different error correcting codes employed in the lattice construction. This approximation is based on the von Mises distribution and achieves, with lower complexity, the same error rate performance obtained with the exact LLR calculation.

关键词： codecs decoding error correction codes LLR estimation MLC error correcting codes error rate performance log-likelihood ratio low-complexity encoding multilevel coding multistage decoding soft decoder von Mises distribution

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A Density Evolution Based Framework for Dirty-Paper Code Design Using TCQ and multilevel LDPC Codes

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IEEE COMMUNICATIONS LETTERS 2012年第10期16卷 1544-1547页

作者： Yang, Yang Xiong, Zixiang Wu Yu-chun Zhang, Philipp Texas A&M Univ Dept ECE College Stn TX 77843 USA Huawei Hisi Adv Res Dept Beijing Peoples R China

We propose a density evolution based dirty-paper code design framework that combines trellis coded quantization with multi-level low-density parity-check (LDPC) codes. Unlike existing design techniques based on Gaussian approximation and EXIT charts, the proposed framework tracks the empirically collected log-likelihood ratio (LLR) distributions at each iteration, and employs density evolution and differential evolution algorithms to design each LDPC component code. The performance of the dirty-paper codes designed using the proposed method comes within 0.37 dB of the theoretical limit at 1 bit per sample transmission rate, achieving an 0.21 dB gain over the best known result.

关键词： Dirty-paper coding log-likelihood ratio low-density parity-check codes multilevel coding trellis-coded quantization

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