Wyniki wyszukiwania - BazTech

1

Evaluation of a high-speed hybrid OAM-OFDM-MDM multiplexed coherent FSO system under desert conditions

Sinha Shivaji, Kumar Chakresh

Optica Applicata

|

2023

|

Vol. 53, nr 3

431--445

EN

To meet the needs of future wireless optical networks, this paper introduces a high-speed, hybrid multiplexed, coherent free-space optical (FSO) communication system that integrates an orbital angular momentum (OAM) multiplexed signal with an orthogonal frequency division multiplexing (OFDM) technique. Two independent QAM polarized beams, each carrying in-phase and quadrature (I/Q) phase 16-QAM-OFDM modulated data, are combined using mode division multiplexing (MDM) to increase the capacity of the proposed system. The reason of choosing OFDM is its capability to support higher data rate, and mitigating intersymbol interference (ISI). The signal is detected using a coherent detection-based digital signal processing (DSP) algorithm at the receiver end. The proposed hybrid FSO system is evaluated in low and heavy dust environments using bit error rate (BER), link distance, optical signal-to-noise ratio (OSNR), and received optical power performance matrices. The simulation results demonstrate the successful transmission of a 120 Gb/s single carrier over the longest link ranges of 1.5 and 0.40 km, respectively, under low and heavy dust weather environments below the signal degradation threshold value (forward error correction (FEC) limit) of BER 2.2 × 10–3 in strong turbulent conditions.

2

Improved Two-Dimensional Double Successive Projection Algorithm for Massive MIMO Detection

Chakraborty Sourav, Sinha Nirmalendu Bika, Mitra Monojit

International Journal of Electronics and Telecommunications

|

2023

|

Vol. 69, No. 1

139--146

EN

In a massive multiple-input multiple-output (MIMO) system, a large number of receiving antennas at the base station can simultaneously serve multiple users. Linear detectors can achieve optimal performance but require large dimensional matrix inversion, which requires a large number of arithmetic operations. Several low complexity solutions are reported in the literature. In this work, we have presented an improved two-dimensional double successive projection (I2D-DSP) algorithm for massive MIMO detection. Simulation results show that the proposed detector performs better than the conventional 2D-DSP algorithm at a lower complexity. The performance under channel correlation also improves with the I2D-DSP scheme. We further developed a soft information generation algorithm to reduce the number of magnitude comparisons. The proposed soft symbol generation method uses real domain operation and can reduce almost 90% flops and magnitude comparisons.

3

Low-Complexity Non-uniform Constellation Demapping Algorithm for Broadcasting System

Wang Chen, Wang Fang, Li Mingqi, Tian Jinfeng

International Journal of Electronics and Telecommunications

|

2019

|

Vol. 65, No. 3

413--420

EN

This paper presents a novel low-complexity soft demapping algorithm for two-dimensional non-uniform spaced constellations (2D-NUCs) and massive order one-dimensional NUCs (1D-NUCs). NUCs have been implemented in a wide range of new broadcasting systems to approach the Shannon limit further, such as DVB-NGH, ATSC 3.0 and NGB-W. However, the soft demapping complexity is extreme due to the substantial distance calculations. In the proposed scheme, the demapping process is classified into four cases based on different quadrants. 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. 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 88.54% is obtained.

4

Modulacja QAM i jej zastosowania w systemach 5G

Grzesiak Krystian, Piotrowski Zbigniew

Elektronika : konstrukcje, technologie, zastosowania

|

2019

|

Vol. 60, nr 4

6--9

PL

Systemy piątej generacji 5G będą umożliwiały przesyłanie informacji z prędkościami rzędu dziesiątek Gb/s. Wysokie przepływności wynikają wprost z zastosowania modulacji wielowartościowych, których główną zaletą jest możliwość zwiększania szybkości transmisji przy zachowaniu szerokości kanału. Wzrost ten jednak okupiony jest większą podatnością na zakłócenia, a związku z tym wymaganym stosunkiem SNR (ang. Signal to Noise Ratio) na wejściu odbiornika. W artykule omówiono możliwości detekcyjne określone bitową stopą błędów (ang. Bite Error Rate, BER) dla sygnału modulacji kwadraturowej amplitudowo-fazowej (ang. Quadrature Amplitude Modulation, QAM) o różnej wartościowości w obecności szumu gaussowskiego. Teoretyczne rozważania zostały poparte badaniami symulacyjnymi.

EN

Fifth generation (5G) mobile systems will provide data rates measured in tens of gigabytes. High data rates directly derives from higher- order modulation, which can increase the data rate within a given bandwidth. Data rate growth is created at the expense of the higher SNR requirements. This article investigates detection of low and higher order QAM signals in the presence Gaussian noise. Theoretical discussion are supported by simulation results.

5

Przegląd metod i technik steganografii radiowej

Staniak Ł.

Przegląd Telekomunikacyjny + Wiadomości Telekomunikacyjne

|

2017

|

nr 8-9

710--714, CD

PL

Niniejszy artykuł stanowi przegląd znanych obecnie metod i technik steganografii radiowej, istniejących jak i zaproponowanych w formie koncepcji. Dokonano próby podstawowej klasyfikacji metod ze względu na sposoby osadzania informacji niejawnej w nośniku informacji w postaci transmisji radiowej. Poprzedzone wstępem do tematyki, rozdziały 3-6 zawierają omówienie metod i technik steganograficznych w schemacie przedmodulacyjnym.

EN

This article provides an overview of the commonly known radio steganography methods and techniques, existing as well as proposed as a concept. An attempt was made basic classification methods due to the ways of embedding classified information in the carrier in the form of radio transmission. Preceded by an introduction to the subject, chapters 3-6 provide an overview of the pre-modulation steganography methods and techniques.

6

QAM: proposed model for quality assurance in CBSS

Kharb L

Advances in Science and Technology. Research Journal

|

2015

|

Vol. 9, nr 27

50--57

EN

Component-based software engineering (CBSE) / Component-Based Development (CBD) lays emphasis on decomposition of the engineered systems into functional or logical components with well-defined interfaces used for communication across the components. Component-based software development approach is based on the idea to develop software systems by selecting appropriate off-the-shelf components and then to assemble them with a well-defined software architecture. Because the new software development paradigm is much different from the traditional approach, quality assurance for component-based software development is a new topic in the software engineering research community. Because component-based software systems are developed on an underlying process different from that of the traditional software, their quality assurance model should address both the process of components and the process of the overall system. Quality assurance for component-based software systems during the life cycle is used to analyze the components for achievement of high quality component-based software systems. Although some Quality assurance techniques and component based approach to software engineering have been studied, there is still no clear and well-defined standard or guidelines for component-based software systems. Therefore, identification of the quality assurance characteristics, quality assurance models, quality assurance tools and quality assurance metrics, are under urgent need. As a major contribution in this paper, I have proposed QAM: Quality Assurance Model for component-based software development, which covers component requirement analysis, component development, component certification, component architecture design, integration, testing, and maintenance.

7

Subcarrier Gain Based Power Allocation in Multicarrier Systems

Abd-Elnaby M., Sedhom G. G., Messiha N. W., Abd El-Samie F. E., Zhu X.

Journal of Telecommunications and Information Technology

|

2014

|

nr 1

62--67

EN

The Orthogonal Frequency Division Multiplexing (OFDM) transmission is the optimum version of the multicarrier transmission scheme, which has the capability to achieve high data rate. The key issue of OFDMsystem is the allocation of bits and power over a number of subcarriers. In this paper, a new power allocation algorithm based on subcarrier gain is proposed to maximize the bit rate. For OFDM systems, the Subcarrier Gain Based Power Allocation (SGPA) algorithm is addressed and compared with the standard Greedy Power Allocation (GPA). The authors demonstrate by analysis and simulation that the proposed algorithm reduces the computational complexity and achieves a near optimal performance in maximizing the bit rate over a number of subcarrier.

8

Fuzzy Model of 16PSK and 16QAM Modulation

Butkiewicz B. S.

International Journal of Electronics and Telecommunications

|

2011

|

Vol. 57, No. 4

437-442

EN

In the paper, a concept of Additive Fuzzy Noise (AFN) channel is introduced. The theoretical equations are derived for Bit Error Rate (BER) and Symbol Error Rate (SER) with some digital modulation scheme in the AFN channel. Following modulations are considered: Phase Shift Keying (16PSK), Quadrature Amplitude Modulation (16QAM). The fuzzy approach to these modulations is presented. The BER and SER values are calculated using possibility theory. The results obtained by fuzzy noise model are compared with conventional approach, where probability models of the noise are used.

9

The effective method of computing the soft-decision metrics in the system with quadrature amplitude modulation

Kliks A.

Poznan University of Technology Academic Journals. Electrical Engineering

|

2007

|

No 54

81-87

EN

The decision on a transmitted symbol is one of the key points in the decoding process of the received signal. The block of demapper, that is responsible for mapping of the constellation points to the binary blocks, produces either the binary data blocks or a set of metrics on its outputs. In this paper, the optimal iterative algorithm of finding the minimal set of metrics - when the data QAM symbols are coded with Grey code - is discussed. At the beginning, the description of OFDM systems and the channel influence on the data transmission in such systems are presented. Then, the main idea of finding metrics is described in detail. The obtained results are discussed and summarized in the conclusion.