scholarly journals SCMA Codebook Design Based on Decomposition of the Superposed Constellation for AWGN Channel

Electronics ◽  
2021 ◽  
Vol 10 (17) ◽  
pp. 2112
Author(s):  
Zhaoyang Hou ◽  
Zheng Xiang ◽  
Peng Ren ◽  
Bohao Cao
Keyword(s):  
Message Passing ◽  
Multiple Access ◽  
Euclidean Distance ◽  
Additive White Gaussian Noise ◽  
Factor Graph ◽  
Codebook Design ◽  
Awgn Channel ◽  
Message Passing Algorithm ◽  
Different Dimensions ◽  
Better Than

In this study, we propose a method named decomposition of the superposed constellation (DCSC) to design sparse code multiple access (SCMA) codebooks for the additive white Gaussian noise (AWGN) channel. We prove that the power of the user symbols (USs) is accurately determined by the power of the superposed constellation (SC). Thus, we select quadrature amplitude modulation (QAM) constellations as the SC and decompose the SC into several groups of USs with power diversity. The minimum Euclidean distance (MED) between superposed symbols (SS-MED) in the receiver is determined by the selected QAM and MED between the multi-dimensional codewords (CW-MED) is optimized by matching the symbols on different dimensions. We propose a simplified DCSC (S-DCSC) by modifying the factor graph and avoiding the transmission of USs with low power, which greatly reduces the complexity of the message passing algorithm (MPA). The simulations show that the SS-MEDs of DCSC and S-DCSC are larger than those in previous papers and the BER performance of the proposed codebooks is better than others.

scholarly journals Nonuniform Code Multiple Access

2018 ◽  
Vol 2018 ◽  
pp. 1-11
Author(s):  
Cheng Yan ◽  
Ningbo Zhang ◽  
Guixia Kang
Keyword(s):  
Message Passing ◽  
Multiple Access ◽  
Sparse Code ◽  
Rate Performance ◽  
Initial Information ◽  
Codebook Design ◽  
Constellation Design ◽  
Message Passing Algorithm ◽  
Sum Of Distances

For sparse code multiple access advanced (SCMAA), the quality of initial information on each resource node and the convergence reliability of the detected user in each decision process were unsatisfactory at the message passing algorithm (MPA) receiver. Driven by these problems, this paper proposes a nonuniform code multiple access (NCMA) scheme. In the codebook design of NCMA, different transmitted layers are generated from different complex multidimension constellations, respectively, and a novel basic complex multidimension constellation design is proposed to increase the minimum intrapartition distance. Then a novel criterion of permutation set is proposed to maximize the sum of distances between interfering dimensions of transmitted codewords multiplexed on any resource node, where the number of nonzero elements of transmitted codewords is more than 1. On the other side, an advanced MPA receiver is proposed to improve the reliability of detection on each transmitted layer of NCMA. Simulation results show that the block error rate performance of NCMA outperforms SCMAA and sparse code multiple access (SCMA) under the same spectral efficiency.

scholarly journals Comparative Analytical Study of SCMA Detection Methods for PA Nonlinearity Mitigation

Sensors ◽  
2021 ◽  
Vol 21 (24) ◽  
pp. 8408
Author(s):  
Elie Sfeir ◽  
Rangeet Mitra ◽  
Georges Kaddoum ◽  
Vimal Bhatia
Keyword(s):  
Message Passing ◽  
Multiple Access ◽  
Reproducing Kernel ◽  
Reproducing Kernel Hilbert Space ◽  
Detection Methods ◽  
Error Floor ◽  
Time Frequency ◽  
Codebook Design ◽  
Message Passing Algorithm ◽  
Random Fourier Features

Non-orthogonal multiple access (NOMA) has emerged as a promising technology that allows for multiplexing several users over limited time-frequency resources. Among existing NOMA methods, sparse code multiple access (SCMA) is especially attractive; not only for its coding gain using suitable codebook design methodologies, but also for the guarantee of optimal detection using message passing algorithm (MPA). Despite SCMA’s benefits, the bit error rate (BER) performance of SCMA systems is known to degrade due to nonlinear power amplifiers at the transmitter. To mitigate this degradation, two types of detectors have recently emerged, namely, the Bussgang-based approaches and the reproducing kernel Hilbert space (RKHS)-based approaches. This paper presents analytical results on the error-floor of the Bussgang-based MPA, and compares it with a universally optimal RKHS-based MPA using random Fourier features (RFF). Although the Bussgang-based MPA is computationally simpler, it attains a higher BER floor compared to its RKHS-based counterpart. This error floor and the BER’s performance gap are quantified analytically and validated via computer simulations.

scholarly journals BER Performance Analysis of Non-Coherent Q-Ary Pulse Position Modulation Receivers on AWGN Channel

Sensors ◽  
2021 ◽  
Vol 21 (18) ◽  
pp. 6102
Author(s):  
Xianhua Shi ◽  
Yimao Sun ◽  
Jie Tian ◽  
Maolin Chen ◽  
Youjiang Liu ◽  
...  
Keyword(s):  
Gaussian Noise ◽  
Additive White Gaussian Noise ◽  
Theoretical Formula ◽  
Pulse Position Modulation ◽  
Error Performance ◽  
Optimal Receiver ◽  
Awgn Channel ◽  
Simulation Results ◽  
The Relationship ◽  
Better Than

This paper introduces the structure of a Q-ary pulse position modulation (PPM) signal and presents a noncoherent suboptimal receiver and a noncoherent optimal receiver. Aiming at addressing the lack of an accurate theoretical formula of the bit error rate (BER) of a Q-ary PPM receiver in the additive white Gaussian noise (AWGN) channel in the existing literature, the theoretical formulas of the BER of a noncoherent suboptimal receiver and noncoherent optimal receiver are derived, respectively. The simulation results verify the correctness of the theoretical formulas. The theoretical formulas can be applied to a Q-ary PPM system including binary PPM. In addition, the analysis shows that the larger the Q, the better the error performance of the receiver and that the error performance of the optimal receiver is about 2 dB better than that of the suboptimal receiver. The relationship between the threshold coefficient of the suboptimal receiver and the error performance is also given.

Overview of Sparse Graph for Multiple Access in Future Mobile Networks

Frequenz ◽  
2017 ◽  
Vol 71 (11-12) ◽  
Author(s):  
Jing Lei ◽  
Baoguo Li ◽  
Erbao Li ◽  
Zhenghui Gong
Keyword(s):  
Wireless Communications ◽  
Mobile Networks ◽  
Message Passing ◽  
Multiple Access ◽  
Low Density ◽  
Sparse Graph ◽  
Extrinsic Information ◽  
Promising Technique ◽  
Satisfactory Performance ◽  
Message Passing Algorithm

AbstractMultiple access via sparse graph, such as low density signature (LDS) and sparse code multiple access (SCMA), is a promising technique for future wireless communications. This survey presents an overview of the developments in this burgeoning field, including transmitter structures, extrinsic information transform (EXIT) chart analysis and comparisons with existing multiple access techniques. Such technique enables multiple access under overloaded conditions to achieve a satisfactory performance. Message passing algorithm is utilized for multi-user detection in the receiver, and structures of the sparse graph are illustrated in detail. Outlooks and challenges of this technique are also presented.

scholarly journals A Threshold-Based Max-log-MPA Low Complexity Multiuser Detection Algorithm

Sensors ◽  
2020 ◽  
Vol 20 (4) ◽  
pp. 1016
Author(s):  
Guanghua Zhang ◽  
Zonglin Gu ◽  
Qiannan Zhao ◽  
Jingqiu Ren ◽  
Weidang Lu
Keyword(s):  
Computational Complexity ◽  
Multiuser Detection ◽  
Message Passing ◽  
Multiple Access ◽  
Low Complexity ◽  
Detection Algorithm ◽  
Necessary Condition ◽  
Threshold Condition ◽  
Message Passing Algorithm ◽  
The Stability

Sparse Code Multiple Access (SCMA) technology is a new multiple access scheme based on non-orthogonal spread spectrum technology, which was proposed by Huawei in 2014. In the algorithm application of this technology, the original Message Passing Algorithm (MPA) has slow convergence speed and high algorithm complexity. The threshold-based MPA has a high Bit Error Ratio (BER) when the threshold is low. In the Maximum logarithm Message Passing Algorithm (Max-log-MPA), the approximation method is used, which will cause some messages to be lost and the detection performance to be poor. Therefore, in order to solve the above problems, a Threshold-Based Max-log-MPA (T-Max-log-MPA) low complexity multiuser detection algorithm is proposed in this paper. The Maximum logarithm (Max-log) algorithm is combined with threshold setting, and the stability of user nodes is considered as a necessary condition for decision in the algorithm. Before message updating, the user information nodes are judged whether the necessary conditions for the stability of the user node have been met, and then the threshold is determined. Only users who meet the threshold condition and pass the necessary condition of user node stability can be decoded in advance. In the whole process, the logarithm domain MPA algorithm is used to convert an exp operation and a multiplication operation into a maximum value and addition operation. The simulation results show that the proposed algorithm can effectively reduce the computational complexity while ensuring the BER, and with the increase of signal-to-noise ratio, the effect of the Computational Complexity Reduction Ratio (CCRR) is more obvious.

Demonstration of Pattern Division Multiple Access With Message Passing Algorithm for Multi-Channel mmWave Uplinks via RoF Mobile Fronthaul

2020 ◽  
Vol 38 (21) ◽  
pp. 5908-5915
Author(s):  
Shuyi Shen ◽  
You-Wei Chen ◽  
Qi Zhou ◽  
Jeff Finkelstein ◽  
Gee-Kung Chang
Keyword(s):  
Message Passing ◽  
Multiple Access ◽  
Message Passing Algorithm

scholarly journals Efficient Sparse Code Multiple Access Decoder Based on Deterministic Message Passing Algorithm

2020 ◽  
Vol 69 (4) ◽  
pp. 3562-3574 ◽  
Author(s):  
Chuan Zhang ◽  
Chao Yang ◽  
Xu Pang ◽  
Wenqing Song ◽  
Wei Xu ◽  
...  
Keyword(s):  
Message Passing ◽  
Multiple Access ◽  
Sparse Code ◽  
Message Passing Algorithm
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