scholarly journals Sparse Signature Matrix Optimization for NOMA under Imperfect CSI

2021 ◽  
Author(s):  
Kun Lu ◽  
Hongwen Yang
Keyword(s):  
Iterative Decoding ◽  
Information Transfer ◽  
Multiple Access ◽  
Rapid Development ◽  
Minimum Mean Square Error ◽  
Accurate Information ◽  
Analysis Tool ◽  
Matrix Optimization ◽  
High Spectral Efficiency ◽  
Signature Matrix

Abstract Non-orthogonal multiple access (NOMA) can support the rapid development of the Internet of Things (IoT) with its potential to support high spectral efficiency and massive connectivity. The low-density superposition modulation (LDSM) scheme is one of the NOMA schemes and uses the sparse signature matrix to reduce multiple access interferences (MAI). In order to improve the NOMA system performance in practice, this paper focuses on designing the sparse signature matrix with a large girth for LDSM under imperfect channel state information (CSI). Based on the orthogonal pilot and linear minimum mean square error (LMMSE) estimation, the LDSM optimized by bare-bone particle swarm optimization (BBPSO) algorithm has a larger girth and can gather more accurate information in the process of iterative decoding convergence. An extrinsic information transfer (EXIT) chart analysis is designed for the LDSM-OFDM system as a theoretical analysis tool. The simulation results show that the optimized LDSM outperforms the reference LDSM system, bringing about a 0.5 dB performance gain.

scholarly journals Incremental gradient algorithm for multiuser detection in multi-carrier DS-CDMA system under modulation schemes

2018 ◽  
Vol 7 (2.6) ◽  
pp. 311
Author(s):  
Sumitra N. Motade ◽  
Anju V. Kulkarni
Keyword(s):  
Spread Spectrum ◽  
Multiple Access ◽  
Minimum Mean Square Error ◽  
Multiple Access Interference ◽  
Gradient Algorithm ◽  
Channel Noise ◽  
Cdma System ◽  
Communication Performance ◽  
Optimum Performance ◽  
Code Division Multiple

Nowadays, Multicarrier Direct sequence code division multiple access (MC DS-CDMA) systems are used in mobile communication. Performance of these systems are limited by multiple access interference (MAI) created by spread-spectrum users in the channel as well as background channel noise. This paper proposes an incremental gradient descent (IGD) multi-user detection (MUD) for MC DS-CDMA system that can achieve near-optimum performance while the number of users is linear in its implementation complexity.  The IGD algorithm make an effort to perform optimum MUD by updating one user's bit decision each iteration in the best way. This algorithm accelerates the gradient algorithm convergence by averaging. When a minimum mean square error (MMSE) MUD is employed to initialize the proposed algorithm, in all cases tested the gradient search converges to a solution with optimum performance. Further, the iterative tests denote that the proposed IGD algorithm provides significant performance for cases where other suboptimum algorithms perform poorly. Simulation compares the proposed IGD algorithm with the conventional detectors. 

scholarly journals The Influence of Financial Inclusion and Macroeconomic on Foreign Direct Investment (FDI) Flows in The Organization of Islamic Cooperation (OIC) Countries

2021 ◽  
Vol 11 (1) ◽  
pp. 71
Author(s):  
Farma Andiansyah
Keyword(s):  
Interest Rates ◽  
Capital Flows ◽  
Foreign Capital ◽  
Panel Data Analysis ◽  
Rapid Development ◽  
Financial Inclusion ◽  
Analysis Tool ◽  
Macroeconomic Variables ◽  
Negative Effect ◽  
Foreign Capital Flows

Foreign capital flows are important factors in the development of sustainable economies, especially in developing countries such as the OIC countries. Lately, the rapid development of the financial sector and macroeconomic stability became a serious concern by foreign investors, where financial inclusion and macroeconomics played an important role in attracting direct foreign capital flows (FDI). The study aims to investigate the role of financial inclusion and macroeconomic variables on the foreign direct flow of capital (FDI) by using data panels in 8 OKI member States during the 2012-2018 time span. The research uses the Fix Effect Model (FEM) Panel data Analysis tool, which is believed to be able to explain the correlation between independent variables and more accurate dependents. As for the results of the study showed that in partial only variable avaibility (the number of branches of the bank/100,000 adults) is a significant positive draws FDI in the OKI country. While on macroeconomic variables the exchange rates have significant negative effect on FDI, while interest rates and economic growth have significant positive relationships in attracting FDI.

scholarly journals Rancang Bangun Sistem Informasi Akademik Berbasis Web: Studi Kasus: SD Negeri 18 Tanah Abang

2021 ◽  
Vol 2 (3) ◽  
pp. 138-156
Author(s):  
Putri Marlina Ariansyah ◽  
Khana Wijaya
Keyword(s):  
Information System ◽  
Elementary Schools ◽  
Data Processing ◽  
Rapid Development ◽  
Educational Institutions ◽  
Accurate Information ◽  
Academic Information ◽  
Computerized System

SD Negeri 18 Tanah Abang is one of the elementary schools located in Tanjung Dalam Village. In line with the rapid development of technology, there are demands on educational institutions or others to provide fast, precise, and accurate information. In processing the data, SD Negeri 18 Tanah Abang has not used a computerized system, therefore the research conducted by the author aims to create an Academic Information System so that it can help and facilitate data processing.

scholarly journals Tinjauan Hukum Kriminalisasi Berita Hoax: Menjaga Persatuan vs. Kebebasan Berpendapat

Kosmik Hukum ◽  
2021 ◽  
Vol 21 (1) ◽  
pp. 44
Author(s):  
Cindy Bella Devina ◽  
Dissa Chandra Iswari ◽  
Go Christian Bryan Goni ◽  
Devi Kimberly Lirungan
Keyword(s):  
Deliberative Democracy ◽  
Information Exchange ◽  
Rapid Development ◽  
Freedom Of Speech ◽  
Accurate Information ◽  
Fake News ◽  
Abuse Of Power ◽  
The Public ◽  
Long Time ◽  
The Media

The existence of hoaxes in Indonesia has been around for a long time. However, the term hoax was widespread and became part of daily conversations in the media and the public during the 2014 and 2019 Presidential Election. The rapid development of social media use and the ease of information exchange accelerated the spread of hoax. Even in the COVID-19 pandemic, hoax news about the corona virus and matters related to it are widespread in the community. This hoax news, both during the Election and the Covid-19 Outbreak, caused much unrest in the community. Some of the hoax news spreaders were jailed for violations of the ITE Law. Various legal practitioners and academics have also suggested that hoax news creators and spreaders be criminalized. This article reviews normatively whether the criminalization of hoax news is feasible for reasons of maintaining stability or needs to be eliminated to maintain freedom of opinion. The author reviews the normative aspects of criminalizing the creation and dissemination of hoax news by using Habermas' theory of deliberative democracy. Through this theory, the writer finds that hoax news makes aspects of democracy such as dialogue that is full of awareness and accurate information unattainable. This is also in line with what the Indonesian constitution wants. However, it is necessary to ensure that the criminalization of hoaxes is not used as an instrument of abuse of power considering that the circulation of hoaxes is a symptom of a problem rather than the root of the problem itself.Keywords: Fake News, Criminalization, Stability, Freedom of Speech, Deliberative Democracy, Legal Revuew

Application of Extrinsic Information Transfer Charts to Anticipate Turbo Code Behavior

2013 ◽  
pp. 97-104
Author(s):  
Izabella Lokshina
Keyword(s):  
Turbo Codes ◽  
Iterative Decoding ◽  
Information Transfer ◽  
Turbo Code ◽  
A Priori ◽  
Substantial Reduction ◽  
International Standards ◽  
Extrinsic Information ◽  
Exit Chart ◽  
Analysis Technique

This paper examines turbo codes that are currently introduced in many international standards, including the UMTS standard for third generation personal communications and the ETSI DVB-T standard for Terrestrial Digital Video Broadcasting. The convergence properties of the iterative decoding process associated with a given turbo-coding scheme are estimated using the analysis technique based on so-called extrinsic information transfer (EXIT) chart. This approach provides a possibility to anticipate the bit error rate (BER) of a turbo code system using only the EXIT chart. It is shown that EXIT charts are powerful tools to analyze and optimize the convergence behavior of iterative systems utilizing the turbo principle. The idea is to consider the associated SISO stages as information processors that map input a priori LLR’s onto output extrinsic LLR’s, the information content being obviously assumed to increase from input to output, and introduce them to the design of turbo systems without the reliance on extensive simulation. Compared with the other methods for generating EXIT functions, the suggested approach provides insight into the iterative behavior of linear turbo systems with substantial reduction in numerical complexity.

Lattice Reduction Algorithm Based Uplink MC-CDMA

2015 ◽  
Vol 738-739 ◽  
pp. 391-396
Author(s):  
Umut Yunus ◽  
Askar Hamdulla ◽  
Zhen Hong Jia ◽  
Kurban Ubul
Keyword(s):  
Communication Systems ◽  
Multiple Access ◽  
Multiple Input Multiple Output ◽  
Lattice Reduction ◽  
Rate Performance ◽  
Multiple Input ◽  
High Spectral Efficiency ◽  
Input Multiple Output ◽  
Cdma Systems ◽  
Multi Access

MC-CDMA integrates the advantages of OFDM with those of CDMA, it has high spectral efficiency, robustness against multi-path propagation and multiple access flexibility. Due to the above mentioned merits, it has been considered as a candidate for future wireless. In recent years, lattice reduction technique is discussed in multiple input multiple output communication systems, and has been shown with its better performance. The purpose of this paper is to express a model for uplink MC-CDMA systems in matrix form and then to propose a lattice reduction aided multiuser detection, in order to ameliorate the affects of inter-carrier interference and multi access interference. The effectiveness of the proposed method is evaluated by the bit error rate performance.

An invasive ant distribution database to support biosecurity risk analysis in the Pacific

2017 ◽  
Vol 23 (3) ◽  
pp. 258 ◽  
Author(s):  
Monica A. M. Gruber ◽  
Meghan Cooling ◽  
Allan R. Burne
Keyword(s):  
Invasive Species ◽  
Risk Analysis ◽  
Native Species ◽  
Small Island ◽  
Accurate Information ◽  
Analysis Tool ◽  
Invasive Ants ◽  
Invasive Ant ◽  
Conflicting Information ◽  
The Pacific

Invasive species are one of the most serious threats to biodiversity. Up-to-date and accurate information on the distribution of invasive species is an important biosecurity risk analysis tool. Several databases are available to determine the distributions of invasive and native species. However, keeping this information current is a real challenge. Ants are among the most widespread invasive species. Five species of ants are listed in the IUCN list of damaging invasive species, and many other species are also invasive in the Pacific. We sought to determine and update the distribution information for the 18 most problematic invasive ant species in the Pacific to assist Small Island Developing States with risk analysis. We compared the information on six public databases, conducted a literature review, and contacted experts on invasive ants in the Pacific region to resolve conflicting information. While most public records were accurate we found some new records had not yet been incorporated in the public databases, and some information was inaccurate. The maintenance of public databases faces an enormous challenge in balancing completeness (~15 000 ant species in this case) with accuracy (the impossibility of constantly surveying) and utility.

scholarly journals Performance analysis of OFDMA and SC-FDMA

2017 ◽  
Vol 8 (2) ◽  
pp. 113-116 ◽  
Author(s):  
M. Al-Rawi
Keyword(s):  
Carrier Frequency ◽  
Orthogonal Frequency Division Multiplexing ◽  
Multiple Access ◽  
High Speed ◽  
Minimum Mean Square Error ◽  
Frequency Division ◽  
International Telecommunication Union ◽  
Single Carrier ◽  
Main Challenge ◽  
Better Than

The main challenge in any high-speed digital communication system is how to maximize the data rate with minimizing the bit error rate. Several techniques have been developed to achieve this point. Some of these techniques are orthogonal frequency division multiplexing (OFDM), single-carrier frequency domain equalization (SC-FDE), orthogonal frequency division multiple access (OFDMA), and single-carrier frequency division multiple access (SC-FDMA). These four techniques are described briefly in this paper. Also, the paper measures the performances of OFDMA and SC-FDMA systems over international telecommunication union (ITU) vehicular-A channel using minimum mean square error (MMSE) equalization. Simulation results show that the performances with interleaved mapping outperform that with localized mapping. Also, the performances with quadrature phase shift keying (QPSK) are better than that with 16-ary quadrature amplitude modulation (16QAM). In addition, the performance of SC-FDMA is better than that of OFDMA, when QPSK is used, but the latter is little bit better than that of SC-FDMA when 16QAM is used.

Research on Key Technologies in Multi-Robotic Spread Spectrum Communication System

2013 ◽  
Vol 756-759 ◽  
pp. 2401-2405 ◽  
Author(s):  
Yun Hang Zhu ◽  
Qiong Cai ◽  
Xiu Liang Huang
Keyword(s):  
Spread Spectrum ◽  
Communication System ◽  
Code Division Multiple Access ◽  
Multiple Access ◽  
Rapid Development ◽  
Direct Sequence Spread Spectrum ◽  
Robotic System ◽  
Direct Sequence ◽  
Walsh Code ◽  
Code Division Multiple

It has become a hot research topic that to improve the coordination performance of multi-robotic system by communication. With rapid development of wireless communication and robot technologies, multi-robotic system based on spread-spectrum technology has become product of combining two technologies. Code Division Multiple Access (CDMA) technology is applied in multi-robotic communication system here. According to the modified m-Walsh sequence got by the way of analyzing the relation characteristic of Walsh-code and m-sequence, the best direct sequence spread spectrum (DSSS) PN code and the improved RAKE receiver scheme are proposed, which satisfied the requirements of real-time performance, reliability and confidentiality in multi-robotic communication system, and have great significance for the research of multi-robotic communication system.

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