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 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 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

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.

Improved Message Passing Algorithms for Sparse Code Multiple Access

2017 ◽  
Vol 66 (11) ◽  
pp. 9986-9999 ◽  
Author(s):  
Jincheng Dai ◽  
Kai Niu ◽  
Chao Dong ◽  
Jiaru Lin
Keyword(s):  
Message Passing ◽  
Multiple Access ◽  
Sparse Code ◽  
Message Passing Algorithms

scholarly journals A review of codebook design methods for sparse code multiple access

2021 ◽  
Vol 22 (2) ◽  
pp. 927
Author(s):  
Syed Aamer Hussain ◽  
Norulhusna Ahmad ◽  
Ibraheem Shayea ◽  
Hazilah Mad Kaidi ◽  
Liza Abdul Latiff ◽  
...  
Keyword(s):  
Bit Error Rate ◽  
Error Rate ◽  
Multiple Access ◽  
Design Methods ◽  
Sparse Code ◽  
Practical Implementation ◽  
Next Generation ◽  
Promising Technique ◽  
Codebook Design ◽  
Optimisation Technique

<span lang="EN-GB">The progressions in telecommunication beyond the 5<sup>th</sup> generation have created a need to improve research drifts. The current 5G study has an important focus on non-orthogonal multiple access (NOMA) technology. sparse code multiple access (SCMA) is a promising technique within NOMA, enhancing the multi-user handling capability of next-generation communication. In the SCMA sphere, codebook designing and optimisation are essential research matters. This study conversed with different codebook design practises existing in the literature, analysing them for numerous parameters, including bit error rate (BER), an optimisation technique, and channel settings. From the analysis, the paper presents the efficiency of different approaches. The article also discusses the prospects and challenges of SCMA optimisation in practical implementation in various domains.</span>

scholarly journals Optimized SCMA Codebook Design Using Rotation Based Sub-Divided Constellation for Overloaded System

2021 ◽  
Author(s):  
Madhura K ◽  
M.S.S. Rukmini ◽  
Rajeshree Raut
Keyword(s):  
Wireless Communication ◽  
Multiuser Detection ◽  
Error Rate ◽  
Multiple Access ◽  
Symbol Error Rate ◽  
Sparse Code ◽  
System Model ◽  
Codebook Design

Abstract 5G in wireless communication aims at deploying massive connectivity. Sparse Code Multiple Access (SCMA), proves to be an emerging candidate with multidimensional codebooks proposing, high shaping gain and advanced multiuser detection. A framework for designing a codebook for 200 % overloaded SCMA system with system model is presented in this paper. This article aims at delineating a codebook by subdividing the Mother Constellation (MC) and rotating it to achieve a better Symbol Error Rate (SER) performance over higher values of SNR. Different Codebook designs are taken into consideration for comparing with the sub-constellation based 200% overloaded SCMA. Abstract — 5G in wireless communication aims at deploying massive connectivity. Sparse Code Multiple Access (SCMA), proves to be an emerging candidate with multidimensional codebooks proposing, high shaping gain and advanced multiuser detection. A framework for designing a codebook for 200 % overloaded SCMA system with system model is presented in this paper. This article aims at delineating a codebook by subdividing the Mother Constellation (MC) and rotating it to achieve a better Symbol Error Rate (SER) performance over higher values of SNR. Different Codebook designs are taken into consideration for comparing with the sub-constellation based 200% overloaded SCMA.

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