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A Universal Low-Complexity Symbol-to-Bit Soft Demapper

Qi Wang, Qiuliang Xie, Zhaocheng Wang, Sheng Chen, Lajos Hanzo
2014 IEEE Transactions on Vehicular Technology  
Moreover, our proposed low-complexity soft demapper attains the same performance as the Max-Log-MAP demapper for PAM, PSK, and QAM, whereas the performance degradation of our low-complexity soft demapper  ...  and 256-ary constellations compared with the Max-Log-MAP demapper.  ...  Albeit the max-sum-approximation-based version of the Log-MAP (Max-Log-MAP) demapper [5] eliminates the high-complexity exponential and logarithmic operations in the Log-MAP algorithm, the number of  ... 
doi:10.1109/tvt.2013.2272640 fatcat:vvarux5fvjeijjrzifqhiauzem

A Reduced-Complexity Demapping Algorithm for BICM-ID Systems

Jiandong Tan, Qi Wang, Chen Qian, Zhaocheng Wang, Sheng Chen, Lajos Hanzo
2015 IEEE Transactions on Vehicular Technology  
However, the complexity of the standard max-sum approximation of the maximum a posteriori probability in log-domain (Max-Log-MAP) invoked by the iterative demapper is on the order of 2 m or O 2 m for a  ...  We demonstrate that this dramatic computational complexity only imposes modest performance degradation with respect to that of the optimal high-complexity Max-Log-MAP scheme.  ...  , in comparison with the standard high-complexity optimal Max-Log-MAP iterative demapper.  ... 
doi:10.1109/tvt.2014.2366195 fatcat:2ebjfmtokfho3a7xyszqrlwmuq

Simplified non-uniform constellation demapping scheme for the next broadcasting system

Sunhyoung Kwon, Sung Ik Park, Jae-young Lee, Heung Mook Kim, Namho Hur, Jeongchang Kim
2015 2015 IEEE International Symposium on Broadband Multimedia Systems and Broadcasting  
Analysis and simulation prove that the proposed demapper only introduces a small penalty under 0.02dB with respect to Max-Log-MAP demapper, whereas a significant complexity reduction ranging from 68.75%  ...  To deal with the complexity problem, four groups of reduced subsets in terms of the quadrant for each bit are separately calculated and stored in advance.  ...  As BER performance comparison of Max-Log-MAP, QSR and the simplified demappers for the 256 NU-QAM with 4BER performance comparison of Max-Log-MAP and the simplified demappers for the 1024 NU-QAM with 5  ... 
doi:10.1109/bmsb.2015.7177239 dblp:conf/bmsb/KwonPLKHK15 fatcat:nyjyuvxgufaurazdbtmguo37ue

A high throughput architecture for a low complexity soft-output demapping algorithm

I. Ali, U. Wasenmüller, N. Wehn
2015 Advances in Radio Science  
For computing the LLR values from a received complex symbol, a soft demapper is employed in the receiver.  ...  These decoders require a soft input, i.e., the logarithmic likelihood ratio (LLR) of the received bits with a typical quantization of 4 to 6 bits.  ...  Optimal soft demapping For M-ary modulation scheme, the demapper needs to calculate log-likelihood ratios on the coded bits c 0 , c 1 , . . ., c M−1 for each incoming received symbol.  ... 
doi:10.5194/ars-13-73-2015 fatcat:ny4miqg7nzejrmcybr7kqibkre

Low-complexity soft-decision aided detectors for coded spatial modulation MIMO systems

Cong Li, Jinlong Wang, Yunpeng Cheng, Yuzhen Huang
2016 EURASIP Journal on Wireless Communications and Networking  
the IPBSD and IQBSD algorithms achieve the same performance as Max-Log-LLR algorithm with reduced computational complexity.  ...  In addition, a comprehensive performance and computational complexity comparison between the proposed algorithms and the Max-Log-LLR algorithm is provided to verify our proposed low-complexity soft-output  ...  For the Log-MAP demapper, the soft information bits can be expressed in the form of the log-likelihood ratio (LLR).  ... 
doi:10.1186/s13638-015-0509-9 fatcat:aya6pitcnnbenj7oxtfbklyhvu

A Universal Low-Complexity Demapping Algorithm for Non-Uniform Constellations

Hao Wang, Mingqi Li, Chao Wang
2020 Applied Sciences  
Analysis and simulation results show that, compared with the Max-Log-MAP algorithm, the proposed algorithm can greatly reduce the demapping complexity of NUC with negligible performance loss.  ...  However, the soft demapping algorithm needs a lot of Euclidean distance (ED) calculations and comparisons, which brings great demapping complexity to NUC.  ...  Acknowledgments: The authors would like to thank the Shanghai Advanced Research Institute, Chinese Academy of Sciences for supporting in this investigative project.  ... 
doi:10.3390/app10238572 fatcat:liijqik565er7g2hrzi2jdynvu

Multidimensional Modulation and Coding in Optical Transport

Magnus Karlsson, Erik Agrell
2017 Journal of Lightwave Technology  
We exemplify how these metrics can be used for system performance as well as to quantify the performance differences between four types of systems; using hard or soft decision on bits or symbols.  ...  We present performance (lower bounds) for higher dimensions by exploiting known performance of binary block codes.  ...  Before the modulator is a mapper, which takes a sequence of m = log 2 M incoming bits and maps them to one of M symbols.  ... 
doi:10.1109/jlt.2016.2615124 fatcat:rc6kqzlr25ht3ar3wbh2hnigj4

On the Information Loss of the Max-Log Approximation in BICM Systems

Mikhail Ivanov, Christian Hager, Fredrik Brannstrom, Alexandre Graell i Amat, Alex Alvarado, Erik Agrell
2016 IEEE Transactions on Information Theory  
We prove that this assumption is correct for all M -PAM constellations and labelings with the exception of a symmetric 4-PAM constellation labeled with a Gray code.  ...  We present a comprehensive study of the information rate loss of the max-log approximation for M -ary pulse-amplitude modulation (PAM) in a bit-interleaved coded modulation (BICM) system.  ...  CONCLUSIONS In this paper, we studied achievable rates of a BICM decoder with both exact and max-log L-values for M -PAM constellations.  ... 
doi:10.1109/tit.2016.2543740 fatcat:ivsydgrqfzhtpd6gqz3shtrima

Signal definition and resource management techniques for upcoming communication and broadcasting systems

Charbel Abdel Nour
2020 Zenodo  
The work concerns code design for binary and non-binary codes with simplified decoding algorithms, their association with high order modulations and multiple antennas, the study of high diversity schemes  ...  for severe channel conditions and the support of high throughput.  ...  However, in practice, applying the BCJR algorithm in the logarithmic domain (Log-MAP algorithm) and possibly simplifying it using the max-log approximation (Max-Log-MAP or MLM algorithm), makes it more  ... 
doi:10.5281/zenodo.5020532 fatcat:nlqm7ld62nhpxiygmjt5sy5m54

Signal definition and resource management techniques for upcoming communication and broadcasting systems

Charbel Abdel Nour
2020 Zenodo  
The work concerns code design for binary and non-binary codes with simplified decoding algorithms, their association with high order modulations and multiple antennas, the study of high diversity schemes  ...  for severe channel conditions and the support of high throughput.  ...  However, in practice, applying the BCJR algorithm in the logarithmic domain (Log-MAP algorithm) and possibly simplifying it using the max-log approximation (Max-Log-MAP or MLM algorithm), makes it more  ... 
doi:10.5281/zenodo.4968707 fatcat:d2zvqd5l5vhq7j6li5kwyc65je

Four-Dimensional Coded Modulation with Bit-Wise Decoders for Future Optical Communications

Alex Alvarado, Erik Agrell
2015 Journal of Lightwave Technology  
Coherent optical communication systems result in a four-dimensional (4D) signal space, which naturally leads to 4D-CM transceivers.  ...  PM-64QAM) outperform the best 4D constellations designed for uncoded transmission.  ...  Domaniç Lavery (University College London) and Tobias Fehenberger (Technische Universität München) for fruitful discussions regarding different parts of this manuscript.  ... 
doi:10.1109/jlt.2015.2396118 fatcat:75ocukyjafg27aalut7rwfseju

Bit-Interleaved Coded Modulation

Albert Guillén i Fàbregas, Alfonso Martinez, Giuseppe Caire
2007 Foundations and Trends in Communications and Information Theory  
More recently, powerful families of binary codes with a good tradeoff between performance and decoding complexity have been (re-)discovered.  ...  Bit-Interleaved Coded Modulation (BICM) is a pragmatic approach combining the best out of both worlds: it takes advantage of the signal-space coding perspective, whilst allowing for the use  ...  Acknowledgments We wish to acknowledge Frans Willems for his contributions in multiple subjects related to BICM, especially the wideband regime and mismatched decoding.  ... 
doi:10.1561/0100000019 fatcat:ucdquzyvpzdgljb77jpltnriim

Probabilistic Constellation Shaping for Optical Fiber Communications

Junho Cho, Peter Winzer
2019 Journal of Lightwave Technology  
As performance metrics for systems with PCS, we compare information-theoretic measures such as mutual information (MI), generalized MI (GMI), and normalized GMI, which enable optimization and quantification  ...  We derive the optimal parameters of PCS and FEC that maximize the IR for both ideal and non-ideal PCS and FEC.  ...  Note that the BMD demapper produces only log 2 M LLRs per received symbol, whereas an SMD demapper produces |X | = M LLRs per received symbol, in the form of log P X |Y (x 1 |y i )/P X |Y (x|y i ) for  ... 
doi:10.1109/jlt.2019.2898855 fatcat:imvzsmxndrdvxou6uhbb3mqxmm

On the Performance of BICM with Trivial Interleavers in Nonfading Channels

Alex Alvarado, Leszek Szczecinski, Erik Agrell
2011 2011 IEEE International Conference on Communications (ICC)  
The reported gains reach a few decibels and are obtained using a less complex BICM system.  ...  Analytical bounds that predict the performance of BICM-T are developed and a new type of distance spectrum for the convolutional code is introduced.  ...  where we used the max-log approximation log(e a + e b ) ≈ max{a, b} and the fact that the channel is Gaussian.  ... 
doi:10.1109/icc.2011.5963205 dblp:conf/icc/AlvaradoSA11 fatcat:3t6yrasfenbdzmzitdmjg4vdvi

Two Decades of MIMO Design Tradeoffs and Reduced-Complexity MIMO Detection in Near-Capacity Systems

Chao Xu, Shinya Sugiura, Soon Xin Ng, Peichang Zhang, Li Wang, Lajos Hanzo
2017 IEEE Access  
Interference (IAI) and perform well with the aid of low-complexity linear receivers without imposing a substantial performance loss on generic ML/MAP aided MIMO detection.  ...  Having said that, in the near-capacity system design, the soft-decision MIMO detection dominates the total complexity, because all the MIMO signal combinations have to be examined, when both the channel's  ...  More specifically, for the soft-decision MMSE, the Log-MAP of (13), the Max-Log-MAP of (15) and the Approx-Log-MAP of (16) may be employed, where the signal sets may be replaced by the classic M PSK/QAM  ... 
doi:10.1109/access.2017.2707182 fatcat:xycdmrnatfbdfdfnogpwuj7bje
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