scholarly journals Enchancement of GSC Using OFDM and QAM Over Reiyleign Fading Channel: A Review

2021 ◽  
pp. 108-114
Author(s):  
Hammed Oyebamiji Lasisi ◽  
Funmilola Margaret Adeagbo ◽  
Bolatito Fatimah Aderinkola
Keyword(s):  
Signal To Noise Ratio ◽  
Physical Distance ◽  
Selection Combining ◽  
Modulation Scheme ◽  
Transmission Scheme ◽  
Available Bandwidth ◽  
Noise Interference ◽  
Mobile Cellular ◽  
Wireless Mobile Communication ◽  
Efficient Power

As indispensable as communication has been to human endeavors, geographical and physical distance would have been a barrier to its effective deployment if not for the advent of wireless mobile communication. In the world today, most of the developments we see in all spheres of our modern life are influenced by communication technologies. However, the performance of each modulation scheme deployed in the communication system dictates the Quality of Service (QoS), effective cost management, efficient power, available bandwidth, Bit Error Rate (BER), and Signal to Noise Ratio (SNR). Extensive research has been done with different authors proffering wide ranging solutions for generalized selection combining (GSC) algorithms in the presence of noise and interfering signals. Some of the reported approaches include varying modulation schemes, changing the channel, and using different equalizing techniques. Many of these proposed solutions worked effectively in some areas while they understandably left other areas untouched, others show better performance by analyzing the channel using; Log-likelihood Ratio (LLR), integral expression, and multiple-mode transmission scheme which in turns proof to be of better performance with a good result. Despite all the efforts, overcoming the issue of noise interference in the communication channel has still been somewhat elusive. Conclusively, to reduce noise to the barest minimum in mobile/cellular communication, this review proposes modulation scheme synchronization with combined diversity technique over an improved channel that is less prone to noise.

scholarly journals Orthogonal frequency division multiplexing with amplitude shift keying subcarrier modulation as a reliable and efficient transmission scheme for self-mixing receivers

2017 ◽  
Vol 15 ◽  
pp. 99-106 ◽  
Author(s):  
Jonas Kornprobst ◽  
Thomas J. Mittermaier ◽  
Thomas F. Eibert
Keyword(s):  
Power Efficiency ◽  
Orthogonal Frequency Division Multiplexing ◽  
Phase Retrieval ◽  
Signal To Noise Ratio ◽  
A Priori ◽  
Strong Dependence ◽  
Equation System ◽  
The Self ◽  
Transmission Scheme ◽  
Available Bandwidth

Abstract. A new receiving scheme for self-mixing receivers is presented that overcomes the disadvantages of the self-heterodyne concept. Generally speaking, the self-mixing receiver offers immunity to phase noise and frequency offsets, especially at very high frequencies, since it does not require radio frequency local oscillators. Our proposed technique eliminates the drawbacks of the self-heterodyne transmission scheme, which are the poor power efficiency and the strong dependence on the continously transmitted carrier. A nonlinear system of equations is constructed that describes a phase retrieval problem for the reconstruction of the original transmit signal before self-mixing. Two different solution strategies, with restrictions in time and frequency domain, are presented. As a consequence, the self-mixing equation system is shown to be solvable with some a-priori information about the transmit signal. With this novel approach, the transmitted information is distributed over the full available bandwidth, and there is no special dependence on a certain subcarrier for the down-conversion. The general performance, regarding bit error ratio over signal to noise ratio, is improved by at least 2 dB as compared to the self-heterodyne transmission scheme. In the case of frequency selective channels, e.g. multi-path propagation, this improvement is shown to be much larger, because the presented approach is able to reconstruct the received subcarriers without the necessity of receiving all subcarriers.

scholarly journals An efficient power constrained transmission scheme for hybrid OW/RF systems

2014 ◽  
Author(s):  
Nestor D. Chatzidiamantis ◽  
Leonidas Georgiadis ◽  
Harilaos G. Sandalidis ◽  
George K. Karagiannidis
Keyword(s):  
Transmission Scheme ◽  
Rf Systems ◽  
Efficient Power

scholarly journals Hybrid Chirp Signal Design for Improved Long-Range (LoRa) Communications

Signals ◽  
2022 ◽  
Vol 3 (1) ◽  
pp. 1-10
Author(s):  
Md. Noor-A-Rahim ◽  
M. Omar Khyam ◽  
Apel Mahmud ◽  
Xinde Li ◽  
Dirk Pesch ◽  
...  
Keyword(s):  
Long Range ◽  
Bit Error Rate ◽  
Modulation Scheme ◽  
Signal Design ◽  
Chirp Signal ◽  
Performance Gain ◽  
Extensive Simulation ◽  
Noise Interference ◽  
Chirp Signals ◽  
Simulation Results

Long-range (LoRa) communication has attracted much attention recently due to its utility for many Internet of Things applications. However, one of the key problems of LoRa technology is that it is vulnerable to noise/interference due to the use of only up-chirp signals during modulation. In this paper, to solve this problem, unlike the conventional LoRa modulation scheme, we propose a modulation scheme for LoRa communication based on joint up- and down-chirps. A fast Fourier transform (FFT)-based demodulation scheme is devised to detect modulated symbols. To further improve the demodulation performance, a hybrid demodulation scheme, comprised of FFT- and correlation-based demodulation, is also proposed. The performance of the proposed scheme is evaluated through extensive simulation results. Compared to the conventional LoRa modulation scheme, we show that the proposed scheme exhibits over 3 dB performance gain at a bit error rate of 10−4.

scholarly journals COMPARATIVE ANALYSIS OF MODULATION SCHEMES USING ADAPTIVE EQUALIZATION AS FADING MITIGATION TECHNIQUE

2012 ◽  
pp. 25-31
Author(s):  
SABITA NAHATA ◽  
SUBRATA BHATTACHARYA
Keyword(s):  
Comparative Analysis ◽  
Data Transmission ◽  
High Speed ◽  
Signal To Noise Ratio ◽  
Multipath Fading ◽  
Symbol Error Rate ◽  
Adaptive Equalization ◽  
Modulation Scheme ◽  
Modulation Schemes ◽  
Mitigation Technique

Inter-symbol interference (ISI) due to multipath fading is a vital problem in high-speed wireless communication which restricts communication quality and capacity. Therefore, in addition to choosing a fading mitigation technique, it is also important to strategically select a modulation scheme for effective data transmission. Recent literature review on wireless standards, such as 3G and 4G indicates that QAM and QPSK are suitable choices for data transmission. In this paper, a comparative analysis on selected modulation schemes is performed in a fading environment. The mitigation of fading is done using adaptive equalization technique. Also, we show that the signal to noise ratio (SNR) is an important parameter to choose. It is observed that, even when an adaptive equalizer is used at the receiver, a very low SNR gives very high symbol error rate (SER). We derive some important conclusions from our simulation result: QPSK shows minimum SER, whereas 256-PSK and 256-PAM perform worse. Given its spectral efficiency and a low SER, the best choice is 256- QAM.

Hardware Efficient Hybrid Encoder for Video Surveillance Application

2020 ◽  
pp. 2150113
Author(s):  
Minesh Patel ◽  
Anand Darji
Keyword(s):  
Video Surveillance ◽  
Integrated Circuit ◽  
Video Processing ◽  
Signal To Noise Ratio ◽  
Scalable Video Coding ◽  
Video Codec ◽  
Available Bandwidth ◽  
Coding Efficiency ◽  
Cell Library ◽  
Processing Techniques

Extensive use of digital multimedia has led to the development of advance video processing techniques for development of multimedia applications. Application such as video surveillance requires 247 recording and streaming. So, the bandwidth and storage costs become significant. With introduction of video streaming over internet, where different kinds of end users request same content with different available bandwidth, it requires scalable video coding (SVC). These challenges can be overcome by developing new techniques to reduce redundancy in subsequent frames and to improve the coding efficiency. In this paper, overlapping weighted linear sum (OWLS) pre-processing method and its hardware architecture are proposed. It is implemented using field progrmmable gate array (FPGA) and the application specific integrated circuit (ASIC) is also developed using TSMC180nm technology standard cell library. Results show improvement in terms of power and area as compared to the existing work. In motion compensated temporal filtering (MCTF), wavelet transform is implemented by temporal filters. Architecture for 5/3 Lifting MCTF is also implemented and compared with baseline H.264 video codec. Simulation results show that the average peak signal to noise ratio (PSNR) improvement is 2.36[Formula: see text]dB. The MCTF design using 5/3 Lifting filter is synthesized for Virtex-5 FPGA and compared with the existing close-loop architecture with better performance.

Fluorescence Information Processing Based on Wavelet De-Noising

2015 ◽  
Vol 734 ◽  
pp. 56-63
Author(s):  
Yong Xin Shao ◽  
Xiao Ping Yang ◽  
Zhi Yong Wang ◽  
Ya Juan Yang
Keyword(s):  
Information Processing ◽  
Fluorescence Lifetime ◽  
Temperature Sensor ◽  
Signal To Noise Ratio ◽  
Measurement Precision ◽  
Measurement Reliability ◽  
Signal To Noise ◽  
Noise Interference ◽  
System Noise ◽  
Interference Measurement

<p>In this paper ,the method of the fluorescence lifetime (FL) in fluorescence optical fiber temperature sensor is used to measure the temperature. During the fluorescence information processing , because of existence of the system noise interference, measurement reliability of fluorescence lifetime has been greatly affected, thereby reducing the temperature measurement precision. This paper presents an improved wavelet threshold de-noising method to signal processing, which improves the signal-to-noise ratio and increases the measurement of fluorescence lifetime precision, reduce the error of temperature measurements at the same time. The experimental results demonstrate that this method is effective.</p>

An Improved Simplified-CE Stopping Criterion for BICM-ID System

2013 ◽  
Vol 846-847 ◽  
pp. 1262-1265
Author(s):  
Miao Miao Li ◽  
Jian Ping Li
Keyword(s):  
Iterative Decoding ◽  
Rayleigh Fading ◽  
Signal To Noise Ratio ◽  
Coded Modulation ◽  
Cross Entropy ◽  
Stopping Criterion ◽  
Transmission Scheme ◽  
Stopping Criteria ◽  
Bit Interleaved Coded Modulation ◽  
Efficient Transmission

Bit-interleaved coded modulation iterative decoding (BICM-ID) is an excellent bandwidth efficient transmission scheme,which owns remarkable bit-error-rate (BER) performance both in additive Gaussian noise (AWGN) channel and Rayleigh fading channel.But it leads to the increase of computational complexity and decoding delay at the receiver at the same time. In order to decrease the unnecessary iterations ,a variety of the stopping criteria are put forward . This paper presents an improved simplified cross-entropy (CE) stopping criterion based on Simplified-CE criterion, which calculates the value of CE just one time when Signal to Noise Ratio (SNR) is under 2dB to simplified the iterative process. Simulation results show that the improved Simplified-CE criterion can own the least iterative number when the SNR is under 2dB.And when the SNR is from 2.5dB to 4dB, it is about 12% less than CE criterion in the average iterative numbers.

scholarly journals Analysis and Design of SCMA-Based Hybrid Unicast-Multicast Relay-Assisted Networks

Sensors ◽  
2019 ◽  
Vol 19 (2) ◽  
pp. 329 ◽  
Author(s):  
Yibo Zhang ◽  
Xiaoxiang Wang ◽  
Dongyu Wang ◽  
Yufang Zhang ◽  
Yanwen Lan
Keyword(s):  
Outage Probability ◽  
Cooperative Diversity ◽  
Signal To Noise Ratio ◽  
Base Station ◽  
Cooperative Transmission ◽  
High Signal ◽  
Transmission Scheme ◽  
Two Stage ◽  
Analysis And Design ◽  
Relay Location

This paper studies a multi-user network model based on sparse code multiple access (SCMA), where both unicast and multicast services are considered. In the direct transmission scheme, the communication between the base station (BS) and the users is completed with one stage, in which the relay is inexistent. In the two-stage cooperative transmission scheme, any number of relays are placed to improve the reliability of wireless communication system. The BS broadcasts the requested message to users and relays in the first stage, and the successful relays forward the message to unsuccessful users in the second stage. To characterize the performance of these two schemes, we derive the exact and approximate expressions of average outage probability. Furthermore, to take full advantage of the cooperative diversity, an optimal power allocation and relay location strategy in the high signal-to-noise ratio (SNR) regime is studied. The outage probability reaches the minimum value when the first stage occupies half of the total energy consumed. Simulation and analysis results are presented to demonstrate the performance of these two schemes. The results show that the two-stage cooperative scheme effectively reduce the average outage probability in SCMA network, especially in the high SNR region.

The Application of Pseudo-Random Sequence in the Properties Measurement of Polymer Optical Fiber

2013 ◽  
Vol 313-314 ◽  
pp. 653-657
Author(s):  
Yan Chun Wang ◽  
Chang Wei Sun
Keyword(s):  
Optical Fiber ◽  
Output Signal ◽  
Signal To Noise Ratio ◽  
Random Sequence ◽  
Measuring Method ◽  
Optical Signal ◽  
Polymer Optical Fiber ◽  
Photoelectric Conversion ◽  
Noise Interference ◽  
Labview Software

A new method for the properties measurement of polymer optical fiber (POF) using pseudo-random sequence is introduced. The light source modulated by pseudo-random sequence is injected into the POF. The output optical signal after photoelectric conversion is made the correlation detection with pseudo-random sequence, and finally the correlation operation is carried out based on Labview software. Because pseudo-random sequence performs well on randomicity and it has the correlation properties similar to that of white noise, interference and noise have little influence on the peak of correlation function during the measurement, and the signal-to-noise ratio (SNR) of the output signal can be improved obviously. The measuring method is studied both theoretically and experimentally. Experimental results show that the SNR of the output signal can be improved by 25~40dB for the signal with SNR-15dB to 6dB, and the measuring precision is improved by this method.

scholarly journals High-Definition Electronic Genome Maps from Single Molecule Data

2017 ◽  
Author(s):  
John S. Oliver ◽  
Anthony Catalano ◽  
Jennifer R. Davis ◽  
Boris S. Grinberg ◽  
Timothy E. Hutchins ◽  
...  
Keyword(s):  
Single Molecule ◽  
Structural Information ◽  
Signal To Noise Ratio ◽  
Physical Distance ◽  
Viscous Drag ◽  
High Signal ◽  
High Definition ◽  
Base Pairs ◽  
Solid State Detector ◽  
Genome Maps

With the advent of routine short-read genome sequencing has come a growing recognition of the importance of long-range, structural information in applications ranging from sequence assembly to the detection of structural variation. Here we describe the Nabsys solid-state detector capable of detecting tags on single molecules of DNA 100s of kilobases in length as they translocate through the detector at a velocity greater than 1 megabase pair per second. Sequence-specific tags are detected with a high signal-to-noise ratio. The physical distance between tags is determined after accounting for viscous drag-induced intramolecular velocity fluctuations. The accurate measurement of the physical distance between tags on each molecule and the ability of the detector to resolve distances between tags of less than 300 base-pairs enables the construction of high-density genome maps.

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