IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology.
Performance Comparison of Uncoded OFDM & Uncoded Adaptive OFDM System Over AW...IOSR Journals
Adaptive OFDM (AOFDM) is the important approach to fourth generation of mobile
communication. Adaptive modulating scheme is employed according to channel fading condition for improving
the performance of OFDM. This gives improved data rate, spectral efficiency & throughput. OFDM is flexible
to adapt modulation schemes on subcarriers according instantaneous signal-to-noise ratio (SNR). In this paper,
we compare Bit Error Rate (BER),Mean Square Error(MSE), Spectral Efficiency, Throughput performance of
uncoded OFDM & uncoded adaptive OFDM with BPSK,QPSK & QAM modulation over AWGN channel.
Performance Comparison of Uncoded OFDM & Uncoded Adaptive OFDM System Over AW...IOSR Journals
Adaptive OFDM (AOFDM) is the important approach to fourth generation of mobile
communication. Adaptive modulating scheme is employed according to channel fading condition for improving
the performance of OFDM. This gives improved data rate, spectral efficiency & throughput. OFDM is flexible
to adapt modulation schemes on subcarriers according instantaneous signal-to-noise ratio (SNR). In this paper,
we compare Bit Error Rate (BER),Mean Square Error(MSE), Spectral Efficiency, Throughput performance of
uncoded OFDM & uncoded adaptive OFDM with BPSK,QPSK & QAM modulation over AWGN channel.
Mitigation of Noise in OFDM Based Plc System Using Filter Kernel DesignIJERA Editor
Power line communication is a technology that transforms power line in to pathway for conveyance of
broadband data. It is cost less than other communication approach and for better bandwidth efficiency OFDM
based PLC system is used. In real PLC environment some electrical appliances will produce noise. To mitigate
this noise filter kernel design is used, so periodic impulsive noise and Gaussian noises are removed from PLC
communication system by using this filter kernel design. MATLAB is used for the simulation and the result
shows that filter kernel is simple and effective noise mitigation technique. Further in future, interference due to
obstacles also wants to be mitigated for the better data transmission without noise.
A Low power discrete time sigma delta ADC consisting of a second order sigma delta modulator and third order Cascaded Integrated Comb (CIC) filter is proposed. The second order modulator is designed to work at a signal band of 20K Hz at an oversampling ratio of 64 with a sampling frequency of 2.56 MHz. It achieves a signal to noise ratio of 85.2dB and a resolution of 14 bits. The CIC digital filter is designed to implement a decimation factor of 64, operating at a maximum sampling frequency of 2.56 MHz. A second order sigma delta modulator is implemented in 0.18micron CMOS technology using full custom design and the third order digital CIC decimation filter is implemented in verilog HDL. The complete Sigma Delta ADC, consisting of analog block of second order modulator and digital block of decimator consumes a
total power 1.96mW.
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology
METHOD FOR REDUCING OF NOISE BY IMPROVING SIGNAL-TO-NOISE-RATIO IN WIRELESS LANIJNSA Journal
The signal to noise ratio (SNR) is one of the important measures for reducing the noise.A technique that uses a linear prediction error filter (LPEF) and an adaptive digital filter (ADF) to achieve noise reduction in a speech and image degraded by additive background noise is proposed. Since a speech signal can be represented as the stationary signal over a short interval of time, most of speech signal can be predicted by the LPEF. This estimation is performed by the ADF which is used as system identification. Noise reduction is achieved by subtracting the reconstructed noise from the speech degraded by additive background noise. Most of the MR image accelerating methods suffers from degradation of acquired images, which is often correlated with the degree of acceleration. However, Wideband MRI is a novel technique that transcends such flaws.In this paper we proposed LPEF and ADF for reducing the noise in speech and also we demonstrate that Wideband MRI is capable of obtaining images with identical quality as conventional MR images in terms of SNR in wireless LAN.
Performance analysis of new proposed window for the improvement of snr & ...eSAT Journals
Abstract
The process of communication becomes quite challenging because of the unwanted electrical signals in a communications system. These undesirable signals, usually termed as noise, are random in nature and interfere with the message signals. As a result the signal which is collected from receiver side is not accurate level .In this respects, filtering of signal is very important because noisy signal can mask some important features of the message signal. Hence it is desirable to reduce this noise for proper analysis of the message signal. The signal to noise ratio (SNR) is one of the important measures for reducing the noise. This paper presents the study of low pass FIR filter using a new window techniques for signal Processing. The newly designed windowing filterpresents a new concept for better signal analysis and disturbance detection in the communication systems.The parameters i.e. Power Spectral Density (PSD), signal to noise ratio (SNR), Error Vector Magnitude (EVM) & Figure of Merit are calculated of original signal and analysis the performance of new proposed window method used for low pass FIR filter. This new windowing filter finds applications in signal analysis, communication system and image compression with a lot of other fields.The results have been concluded using MATLAB R2012 software. Index Terms:Window method for Noise reduction, Figure of Merit, SNR, EVM, New window performance
Low Peak to Average Power Ratio and High Spectral Efficiency Using Selective ...theijes
A low complexity peak to average power ratio (PAPR) reduction scheme for orthogonal frequency division multiplexing (OFDM) systems is proposed. All pass filters technique used PAPR is reduction but small amount of reduction, So use Selective Mapping (SLM) technique reduce PAPR and SNR increases.
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology.
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology.
Mitigation of Noise in OFDM Based Plc System Using Filter Kernel DesignIJERA Editor
Power line communication is a technology that transforms power line in to pathway for conveyance of
broadband data. It is cost less than other communication approach and for better bandwidth efficiency OFDM
based PLC system is used. In real PLC environment some electrical appliances will produce noise. To mitigate
this noise filter kernel design is used, so periodic impulsive noise and Gaussian noises are removed from PLC
communication system by using this filter kernel design. MATLAB is used for the simulation and the result
shows that filter kernel is simple and effective noise mitigation technique. Further in future, interference due to
obstacles also wants to be mitigated for the better data transmission without noise.
A Low power discrete time sigma delta ADC consisting of a second order sigma delta modulator and third order Cascaded Integrated Comb (CIC) filter is proposed. The second order modulator is designed to work at a signal band of 20K Hz at an oversampling ratio of 64 with a sampling frequency of 2.56 MHz. It achieves a signal to noise ratio of 85.2dB and a resolution of 14 bits. The CIC digital filter is designed to implement a decimation factor of 64, operating at a maximum sampling frequency of 2.56 MHz. A second order sigma delta modulator is implemented in 0.18micron CMOS technology using full custom design and the third order digital CIC decimation filter is implemented in verilog HDL. The complete Sigma Delta ADC, consisting of analog block of second order modulator and digital block of decimator consumes a
total power 1.96mW.
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology
METHOD FOR REDUCING OF NOISE BY IMPROVING SIGNAL-TO-NOISE-RATIO IN WIRELESS LANIJNSA Journal
The signal to noise ratio (SNR) is one of the important measures for reducing the noise.A technique that uses a linear prediction error filter (LPEF) and an adaptive digital filter (ADF) to achieve noise reduction in a speech and image degraded by additive background noise is proposed. Since a speech signal can be represented as the stationary signal over a short interval of time, most of speech signal can be predicted by the LPEF. This estimation is performed by the ADF which is used as system identification. Noise reduction is achieved by subtracting the reconstructed noise from the speech degraded by additive background noise. Most of the MR image accelerating methods suffers from degradation of acquired images, which is often correlated with the degree of acceleration. However, Wideband MRI is a novel technique that transcends such flaws.In this paper we proposed LPEF and ADF for reducing the noise in speech and also we demonstrate that Wideband MRI is capable of obtaining images with identical quality as conventional MR images in terms of SNR in wireless LAN.
Performance analysis of new proposed window for the improvement of snr & ...eSAT Journals
Abstract
The process of communication becomes quite challenging because of the unwanted electrical signals in a communications system. These undesirable signals, usually termed as noise, are random in nature and interfere with the message signals. As a result the signal which is collected from receiver side is not accurate level .In this respects, filtering of signal is very important because noisy signal can mask some important features of the message signal. Hence it is desirable to reduce this noise for proper analysis of the message signal. The signal to noise ratio (SNR) is one of the important measures for reducing the noise. This paper presents the study of low pass FIR filter using a new window techniques for signal Processing. The newly designed windowing filterpresents a new concept for better signal analysis and disturbance detection in the communication systems.The parameters i.e. Power Spectral Density (PSD), signal to noise ratio (SNR), Error Vector Magnitude (EVM) & Figure of Merit are calculated of original signal and analysis the performance of new proposed window method used for low pass FIR filter. This new windowing filter finds applications in signal analysis, communication system and image compression with a lot of other fields.The results have been concluded using MATLAB R2012 software. Index Terms:Window method for Noise reduction, Figure of Merit, SNR, EVM, New window performance
Low Peak to Average Power Ratio and High Spectral Efficiency Using Selective ...theijes
A low complexity peak to average power ratio (PAPR) reduction scheme for orthogonal frequency division multiplexing (OFDM) systems is proposed. All pass filters technique used PAPR is reduction but small amount of reduction, So use Selective Mapping (SLM) technique reduce PAPR and SNR increases.
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology.
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology.
Enhanced equally distributed load balancing algorithm for cloud computingeSAT Publishing House
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology.
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology.
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology.
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology.
A novel method for detecting and characterizing low velocity impact (lvi) in ...eSAT Publishing House
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology.
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology
Effect of modulus of masonry on initial lateral stiffness of infilled frames ...eSAT Publishing House
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology.
Software testing effort estimation with cobb douglas function a practical app...eSAT Publishing House
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology.
Efficient document compression using intra frame prediction tecthniqueeSAT Publishing House
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology.
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology.
“Development and performance analysis of a multi evaporating system”eSAT Publishing House
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology
Screening of antibacterial and cytotoxic activity of extracts from epidermis ...eSAT Publishing House
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology.
A comprehensive review on performance of aodv and dsdv protocol using manhatt...eSAT Publishing House
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology
Distance protection of hvdc transmission line with novel fault location techn...eSAT Publishing House
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology
Pulse shaping methods for inter carrier interference reduction in OFDM systemTELKOMNIKA JOURNAL
The weakness of the orthogonal freuency division multiplexing (OFDM) system is susceptible to the existence of carrier frequency offset (CFO) which causes the emergence of inter carrier interference (ICI) which causes a degradation of performance OFDM systems. This study aims to apply the suggested rectangular (REC) pulse and improved sinc-power (ISP) pulse shaping methods on OFDM system and determines ICI reduction with the effects of CFO over flat fading Rayleigh channels. The performance of each pulse shaping method is evaluated and compared based on parameter ICI power vs. normalized frequency offset, signal to interference ratio (SIR) vs. normalized frequency offset and bit error rate (BER) vs. energy bit per noise (Eb/No). The simulation result in terms of BER vs. Eb/No indicated that REC and ISP pulse shaping has better performance dealing with ICI reduction compared to OFDM system no applied pulse shaping. In addition, the ISP is able to mitigate ICI better than REC.
First order sigma delta modulator with low-power consumption implemented in a...eSAT Journals
Abstract
This paper presents a design of a switched-capacitor discrete time 1st order Delta-Sigma modulator used for a resolution of 8 bits
Sigma-Delta analog to digital converter. For lower power consumption, the use of operational transconductance amplifier is
necessary in order to provide wide output voltage swing and moderate DC gain. Simulation results showed that with 0.35um CMOS
technology, 80 KHz signal bandwidth and oversampling rate of 64, the modulator achieved 49.25 dB Signal to Noise Ratio (SNR) and
the power consumption was 5.5 mW under ±1.5V supply voltage .
Index terms: Analog-to-Digital conversion, Delta-Sigma modulation, CMOS technology, Transconductance operational
amplifier.
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology.
Digital Implementation of Costas Loop with Carrier RecoveryIJERD Editor
Demodulator circuit is a basic building block of wireless communication. Digital implementation of
demodulator is attracting more attention for the significant advantages of digital systems than analog systems.
The carrier signal extraction is the main problem in synchronous demodulation in design of demodulator based
on Software Defined Radio. When transmitter or receiver in motion, it is difficult for demodulator to generate
carrier signal same in frequency and phase as transmitter carrier signal due to Doppler shift and Doppler rate.
Here the digital implementation of Costas loop for QPSK demodulation in continuous mode is discussed with
carrier recovery using phase locked loop.
Effects of filtering on ber performance of an ofdm systemeSAT Journals
Abstract In upcoming generations, wireless communication system requires a higher standard in order to provide high quality of services to customers. Orthogonal Frequency Division Multiplexing (OFDM) is an efficient modulation technique of forthcoming wireless systems which can be implemented easily. In this paper, an effort has been made to analyze how well an OFDM system can perform when a signal is transmitted over an Additive White Gaussian Noise (AWGN) channel using 16 QAM modulation techniques. The performance of OFDM system with pulse shaping filters are also evaluated and results reveal that the pulse shaped OFDM improve the overall performance of the system in terms of BER. We use Different pulse shaping filters such asRaised cosine, FIR Nyquist and SQRT Raised Cosine for analyzingthe Bit Error Rate (BER) performance. Index Terms: AWGN, ICI, OFDM, Bit Error Rate.
Adaptive Clipping for PAPR Reduction in OFDMIJERA Editor
A new Technique “Adaptive Clipping” is introduced to reduce the Peak to Average Power Ratio (PAPR) of OFDM system efficiently for wireless applications. In this technique, the threshold for clipping the signal is decided according to the peak size and number of peaks in the OFDM burst signal. A comparison is done between selective clipping and adaptive clipping and the results are shown in terms of Bit error rate (BER) and PAPR. Adaptive clipping offers nearly half a dB reduction in PAPR compared to selective clipping. With proposed adaptive clipping, PAPR of 3 dB is obtained with BER of 10-4 . For a particular set of signals where there are large number of peak variations, adaptive clipping is more efficient in terms of BER compared to selective clipping. The simulation of adaptive clipping is done with the MATLAB software and the BER is plotted. An IEEE 806.11 standard is used for OFDM signal Transmission.
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology.
The peer-reviewed International Journal of Engineering Inventions (IJEI) is started with a mission to encourage contribution to research in Science and Technology. Encourage and motivate researchers in challenging areas of Sciences and Technology.
Advanced approach for reducing papr in ofdm systems to minimize interference ...eSAT Journals
Abstract
Orthogonal Frequency Division Multiplexing is a popular modulation scheme and finds its use in wireless communication and mostly drawing attention towards 4G mobile communication. Wireless Technology is cardinal as it offers high data rate transmission, which is needed for efficacious communication. The main features of OFDM technique are that it can easily acclimate to severe channel conditions without complex time-domain equalization and is vigorous against Intersymbol Interference (ISI) and fading caused by multipath propagation. But the OFDM system faces the problem of PAPR i.e. Peak to Average Power Ratio. This PAPR effect is tried to be reduced using a combined technique which makes use of clipping and filtering technique along with companding technique. The simulation results show us that the PAPR value reduces to 4.41dB with a value of 128 subcarriers. Earlier used approaches for PAPR reduction were SLM, PTS, Tone reservation etc. The proposed approach shows that PAPR effect is tried to be reduced to a great extent.
Key Words: OFDM, PAPR, BER ,FFT, IFFT etc
Ber performance of ofdm with discrete wavelet transform for time dispersive c...eSAT Publishing House
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology
Design and implementation of different audio restoration techniques for audio...eSAT Journals
Abstract
Audio signals are corrupted with many types of distortions. Major audio distortions are categorized into Globalized and
Localized distortions. Localized distortion includes clipping and clicks where only certain samples are affected and globalized
distortions include broadband noise where complete bandwidth is consumed by noise. Audio restoration is a technique for giving
back the audio signals from these distortions. In this paper, audio restoration techniques for removing clipping, clicks and
broadband noise are put forwarded. Recent approaches to solving audio restoration problem is with respect to sparse
representation algorithms. Clipping distortion is addressed with a Sparse representation framework, it is treated as a reverse
problem, where the distorted samples is estimated from the surrounding undistorted samples, they are embedded in frame based
scheme, and reconstructed by using an overlap add method in conjunction with OMP algorithm and Gabor/DCT dictionary for
modelling audio signals. Broadband denoising is done by using spectral subtraction and Click removal is done by using an
adaptive filter method as the first step. Performance measures are done based on perception, average SNR calculation and
defined parameter variations. This paper also targeting towards the software and hardware implementation of the restoration
methods using TMS320C6713 DSK kit with help of tools mainly MATLAB and Code Composer studio.
Key Words: Audio Distortions, OMP algorithm, Gabor/DCT dictionary, TMS320C6713DSK
This project describes a novel architecture based on Recursive Running Sum (RRS) filter implementation for wire and wireless data processing. UARTs are used for asynchronous serial data communication between remote embedded systems. If physical channel is noisy then, serial data bits get corrupted during transmission. The UART core described here, utilizes recursive running sum filter to remove noisy samples. Input data signal is directly sampled with system clock and samples are accumulated over a window size. The window size is user programmable and it should be set to one tenth of required bit period. The intermediate data bit is decoded using magnitude comparator. The advantage of this architecture is that baud rate is decided by the window size so there is no need of any external “timer module” which is normally required for standard UARTs. The Recursive Running Sum (RRS) filter architecture with programmable window size of M is designed and modules are implemented with VHDL language. This project implementation includes many applications in wireless data communication Systems like RF, Blue tooth, WIFI, ZigBee wireless sensor applications. Total coding written in VHDL language. Simulation in Modelsim Simulator, Synthesis done by XILINX ISE 9.2i. Synthesis result is verified by the Chipscope. Input signal given from the keyboard and output is seen by the help of HyperTerminal.
Reduction of PAPR of OFDM Using Exponential Companding Technique with Network...AM Publications
In this paper a new Exponential companding technique with Network coding is proposed to reduce the Peak-to-
Average Ratio (PAPR) and Bit-Error-Rate in Orthogonal Frequency Division Multiplexing (OFDM) signals. By uniformly
distribution of transmitted OFDM signals, the proposed technique effectively reduces the PAPR by compressing the peak signals
and expanding the small signals, unlike the Mu-law companding technique. The Mu-law companding only enlarging small
signal but our Exponential companding adjust both small as well as large signals without changing the average power by
properly choosing transform parameters. Our simulations results, which consider a baseband OFDM system with Additive White
Gaussian Noise (AWGN) channel, Binary Symmetric Channel (BSC) and a Solid State Power Amplifier (SSPA) shows that the
proposed exponential companding technique can offer better PAPR reduction, Bit Error Rate (BER) than the Conventional
coding and Mu-law companding.
Multi band, multi mode digital rf receiver front end module for m-wimaxeSAT Publishing House
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology
Similar to Comparison of various noise mitigation technique used (20)
Immunizing Image Classifiers Against Localized Adversary Attacksgerogepatton
This paper addresses the vulnerability of deep learning models, particularly convolutional neural networks
(CNN)s, to adversarial attacks and presents a proactive training technique designed to counter them. We
introduce a novel volumization algorithm, which transforms 2D images into 3D volumetric representations.
When combined with 3D convolution and deep curriculum learning optimization (CLO), itsignificantly improves
the immunity of models against localized universal attacks by up to 40%. We evaluate our proposed approach
using contemporary CNN architectures and the modified Canadian Institute for Advanced Research (CIFAR-10
and CIFAR-100) and ImageNet Large Scale Visual Recognition Challenge (ILSVRC12) datasets, showcasing
accuracy improvements over previous techniques. The results indicate that the combination of the volumetric
input and curriculum learning holds significant promise for mitigating adversarial attacks without necessitating
adversary training.
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Comparison of various noise mitigation technique used
1. IJRET: International Journal of Research in Engineering and Technology eISSN: 2319-1163 | pISSN: 2321-7308
__________________________________________________________________________________________
Volume: 02 Issue: 09 | Sep-2013, Available @ http://www.ijret.org 279
COMPARISON OF VARIOUS NOISE MITIGATION TECHNIQUE USED
WITH CLIPPING FOR REDUCTION OF PAPR IN OFDM
Hemant Choubey1
, Aparna Singh2
, Amit Shukla3
1, 3
Student, 2
Asst Professor, Electronics and Communication, UIT, M.P, India
hemantchoubey271986@gmail.com, aparna.kushwah@gmail.com, amit.rgi@gmail.com
Abstract
A simple technique used to reduce the PAPR of OFDM signals is to clip the signal to a maximum allowed value, at the cost of BER
degradation and out-of-band radiation. Clipping does not add extra information to the signal and high peaks occur with low
probability so the signal is seldom distorted. Out-of-band radiation can be reduced by filtering at the transmitter, the filter used in this
project consists on a FFT-IFFT pair which is easier to implement than traditional FIR filters and allows the implementation of the
clip & filter set several times in order to reduce the peak re growth that filtering introduces. The BER degradation can be mitigated by
reconstructing the signal at the receiver. We analyzed the performance of the decision-aided reconstruction (DAR) and improved DAR
(IDAR) techniques that iteratively try to guess the original symbols and proposed an improvement for one of those techniques.
Index Terms: Complementary cumulative distribution function (CCDF),high power amplifier (HPA), Orthogonal
Frequency Division Multiplexing (OFDM), Peak-to-Average Power Ratio (PAPR), inter-symbol interference (ISI)
-----------------------------------------------------------------------***-----------------------------------------------------------------------
1. INTRODUCTION
Introducing a filter after the clipping operation helps
mitigating the out-of-band radiation introduced by clipping.
Filtering, however, distorts also the signal and causes peak re
growth [6]. A common filter used for this purpose is the FIR
filter. In this application the filter used is the FFT-IFFT filter
proposed by Armstrong in [1]. This filter achieves better
performance than the FIR filter, it introduces less noise into
the signal, causes less peak regrowth and needs less
computation; since it operates symbol by symbol it causes no
inter-symbol interference. Clipping too large peaks is a simple
solution to the PAPR problem. Clipping belongs to the group
of techniques that reduce large peaks by nonlinearly distorting
the signal [8]. It does not add extra information to the signal
and too large peaks occur with low probability so the signal is
seldom distorted. The maximum peak power allowed is
determined by the system specifications, usually by the linear
region of the power amplifier. A maximum peak amplitude A
is chosen so that the OFDM signal does not exceed the limits
of this region, symbols that exceed this maximum amplitude,
will be clipped. The clipping function is performed in digital
time domain, before the D/A conversion as shown in Figure 1
and the process is described by the following expression
, 0 (1)
Where xck is the clipped signal, xk is the transmitted signal, A
is the clipping amplitude and f (xk) is the phase of the
transmitted signal xk. The graphical expression of this function
is shown in Figure 2. The clipping ratio (CR) is defined as
C.R = (2)
Fig1.Clipping in the transmitter
Fig2.Clipping Function
2. IJRET: International Journal of Research in Engineering and Technology eISSN: 2319-1163 | pISSN: 2321-7308
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Volume: 02 Issue: 09 | Sep-2013, Available @ http://www.ijret.org 280
Clipping is a non-linear process so it introduces in-band
distortion (Figure 3), also called clipping noise, and out-of-
band radiation and inter-carrier interference (Figure 4), which
degrade the system performance and the spectral efficiency.
The clipping noise is related to the difference between the
original signal xk and the clipped signal . The signal sent to
the receiver is the clipped signal, which is different from the
signal that we actually wanted to send. This difference is
measured by the signal to clipping noise ratio (SCNR)
SCNR = (3)
Fig3.SCNR measured for different number of subcarrier
Fig4.Out of band radiation
2.NOISEMITIGATION
After clipping the signal, the out-of-band radiation caused by
clipping falls in the zeros and then the signal is passed to the
FFT filter. The FFT function transforms the clipped signal
to frequency domain yielding . The information components
of are passed unchanged to the IFFT block and the out-of-
band radiation that fell in the zeros is set back to zero. The
IFFT block of the filter transforms the signal to time domain
and the obtained signal is passed to the D/A converter.
After filtering, the signal suffers peak regrowth so in order to
minimize this effect the clip & filter process can be repeated
several times.
3. NOISE MITIGATION METHODS
3.1 Decision-Aided Reconstruction (DAR) Method
The goal of the clipping operation is to reduce the PAPR of
the original signal xk; it introduces, however, some distortion
that makes the recovering of xk in the receiver more difficult.
The DAR method was proposed by Kim and Stuber in [5] in
order to mitigate the effects of the distortion introduced by
clipping [5].It is a nonlinear iterative reconstruction technique
implemented in the receiver. To implement this technique, the
receiver needs to know the clipping ratio A used at the
transmitter. The signal sent by the transmitter in frequency
domain can be expressed as
Yn = anXn+Cn (4)
Where αn is the clipping distortion, which changes randomly
from block to block and Cn are the noise introduced by
lipping. The received signal is therefore
Zn = hnYn+Wn = hnanXn+Qn (5)
Where hn is the complex channel gain, that can be accurately
estimated, and Qn is the sum of the additive white Gaussian
noise (AWGN) and the clipping noise Cn. In all the
simulations performed in this project ideal channel estimation
is supposed . Figure 5 shows the block diagram of the DAR
method, where rk is the received signal Zn in time domain.
Fig5. DAR algorithm block diagram
3. IJRET: International Journal of Research in Engineering and Technology eISSN: 2319-1163 | pISSN: 2321-7308
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Volume: 02 Issue: 09 | Sep-2013, Available @ http://www.ijret.org 281
If the CR is too low (this depends on the modulation), the
performance of DAR is degraded because false detection
increases.
3.2 Improved Decision-Aided Reconstruction (IDAR)
Method
The DAR method was proposed to mitigate the clipping noise
but it does not deal with the intermodulation noise . The inter-
modulation products are reduced by setting the IBO of the
power amplifier at the linear region; however, in order to
maximize the power efficiency of the amplifier, the IBO is set
nearly at the saturation region degrading this way the BER due
to the high non-linearity. The improved DAR method
mitigates both the clipping noise and the inter-modulation
noise. The IDAR method [2], like the DAR one, is an iterative
method applied at the receiver and was proposed by
Boonsrimuang et al. in [2], Figure 6 shows the block diagram.
It repeats at the receiver the clipping and the amplifying
operations, so the receiver needs to know the clipping
amplitude A and the amplifier characteristics. In Figure 6 can
be seen that the method starts by estimating the original signal
like in the DAR method
Fig6. IDAR algorithm block diagram
By using this method the intermodulation noise is mitigated,
relatively even when the nonlinear amplifier is operated at the
saturation region, while with DAR the BER is severely
affected by this noise. Although the method shows a good
performance for different required signal to noise ratios, for
CR lower than 3 dB around 0 dB.
3.3 IDAR Including the FFT-IFFT Filter (IDARF)
The IDAR method shows a very good performance by
mitigating the clipping and the intermodulation noises.
However, in order to reduce the out-of-band radiation it is
advisable to use a filter in the transmitter; in this case the filter
used is the FFT-IFFT filter. So, if the clipping operation is
followed by the filter at the transmitter, this filter should also
be included in the IDAR method at the receiver, Figure7
shows a block diagram of the new method. In order to include
the FFT filter in the IDARF method, the same number of zeros
as in the transmitter are inserted into the estimated signal
before converting it to time domain. Clip &filter is applied to
the time domain signal which is then amplified like in the
IDAR method. The zeros are removed from the signal after the
amplifier; the signal is transformed to frequency domain, the
zeros are removed and the signal is transformed back to time
domain in order to calculate the error signal. The error signal
is the difference between the estimated signal (before
adding the zeros) and the signal that suffered the clip&filter
and amplifying process, , after removing the zeros. The red
boxes in Figure7 show the operations that have to be added to
the IDAR algorithm in order to include the FFT filter in the
method.
Fig7. IDARF algorithm block diagram
4. SIMULATION RESULTS
After theoretically studying noise mitigation techniques, these
techniques have been tested both in a flat fading channel and
in a selective fading channel. The simulations have been made
for the 16-QAM and the 64-QAM modulations and all them
use 256 subcarriers, when analyzing the system for different
CR, the SNR used varies depending on the modulation, this
information is available in Table 3. The frequency selective
channel parameters are shown in Table 1 and the number of
iterations used for each method is shown in Table 2.
Table 1: Channel parameters
tap delay tap coeff
h0 0.0 0.8405
h1 0.3 0.4726
h2 1.0 0.2658
4. IJRET: International Journal of Research in Engineering and Technology eISSN: 2319-1163 | pISSN: 2321-7308
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Volume: 02 Issue: 09 | Sep-2013, Available @ http://www.ijret.org 282
Table 2: number of iterations
tap delay
clip&filter 1
DAR 2
IDAR 2
IDARF 2
Table 3: system parameters
number of subcarriers 256
CR 4dB
SNR 16QAM 15dB
SNR 64QAM 20dB
4.1 Flat Fading Channel
This section shows the performance of the BER of OFDM
signals modulated with 16 and 64QAM and in a flat fading
channel when varying the SNR and the CR .Figures 8, 9 and
10 show the BER performance of a 16QAM modulation when
varying the SNR from 0 to 18 dB.The simulations in Figure 8
show the performance of the DAR and IDAR methods when
no filter is applied at the transmitter. The results show that the
BER performance for DAR and for IDAR is very similar,
being IDAR slightly better. When the FFT filter is used at the
transmitter, IDARF shows clearly better performance than
DAR and IDAR. Figure 10 shows that IDARF is also better
than IDAR without filter at the transmitter, keeping the BER
very close to that of the no clipping case.
Fig 8: DAR and IDAR methods with no filter in the
transmitter, 16QAM modulation in flat fading channel, CR=4
dB, N=256 subcarriers
Fig 9: IDARF, DAR and IDAR methods with filter in the
transmitter, 16QAMmodulation in flat fading channel, CR=4
dB, N=256 subcarriers
Fig 10: DAR, IDAR and IDARF methods with and without
filter in the transmitter,16QAM modulation in flat fading
channel, CR=4 dB, N=256 subcarriers
Figures 11, 12 and 13 show the same simulations as the
previous figures but this time holding the SNR at 15 dB and
varying the CR from 2 to 14 dBs. For CR > 4 dB, the
performance of DAR and IDAR in Figure 11, when no filter is
applied, is approximately the same, for CR< 4 dB performs
better than DAR. When the filter is applied, Figure 12, and for
CR < 8 dB approximately, IDARF provides a significant
better performance than DAR or IDAR and DAR provides no
improvement compared to just clip&filter, also the difference
between IDARF and DAR or IDAR without filter in the
transmitter is very small, see Figure 13. As the CR decreases,
the performance of all methods degrades, being DAR without
filtering at the transmitter the one that faster degrades. From a
5. IJRET: International Journal of Research in Engineering and Technology eISSN: 2319-1163 | pISSN: 2321-7308
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CR of 8 dB the performance of all methods becomes flat and
similar for all them.
Fig11: DAR and IDAR methods with no filter in the
transmitter, 16QAM modulation in flat fading channel,
SNR=15 dB, N=256 subcarriers
Fig 12: IDARF, DAR and IDAR methods with filter in the
transmitter, 16QAM modulation in flat fading channel,
SNR=15 dB, N=256 subcarriers
Fig13: DAR, IDAR and IDARF methods with and without
filter in the transmitter, 16QAM modulation in flat fading
channel, SNR=15 dB, N=256 subcarriers
Figures 14, 15 and 16 show the BER performance of a
64QAM modulation when varying the SNR from 0 to 30 dB
and for a clipping ratio of 4 dB. In Figure 4.7, when no filter is
applied at the transmitter, the IDAR method performs clearly
better than DAR for SNR> 12 dB approximately, for lower
SNR their performance is nearly the same. For an SNR < 20
dB they behave like when no clipping is applied and after that
they behave like when just clipping is applied. When the filter
is used in the transmitter, Figure 4.8, the performance of
IDARF for the whole SNR range is very close to that when no
clipping is applied, on the other hand, there is nearly no
difference between using IDAR and using just clip&filter.
When comparing all methods in Figure 4.9, IDARF performs
clearly better than DAR and IDAR without filter in the
transmitter.
Fig 14: DAR and IDAR methods with no filter in the
transmitter, 64QAM modulation in flat fading channel, CR=4
dB, N=256 subcarriers
Fig 15: IDARF, DAR and IDAR methods with filter in the
transmitter, 64QAMmodulationin flat fading channel, CR=4
dB, N=256 subcarriers
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Fig 16: DAR, IDAR and IDARF methods with and without
filter in the transmitter,64 QAM modulation in flat fading
channel, CR=4 dB, N=256 subcarriers
Figures 17, 18 and 19 show how those methods behave when
holding the SNR at 20 dB and varying the CR from 2 to 14
dB. Without filter in the transmitter, Figure 17, IDAR
performs slightly better than DAR for CR < 5 dB, after that
the performance is approximately the same. With filter in the
transmitter, 18, IDARF performs much better than the other
methods for CR < 9 dB and using DAR yields the same results
as just clip&filter. Regarding the whole set of methods, Figure
19, IDARF performs better than IDAR and DAR for CR < 6
dB.
Fig 17: DAR and IDAR methods with no filter in the
transmitter, 64QAM modulation in flat fading channel,
SNR=20dB,N=256 subcarriers
Fig 18: IDARF, DAR and IDAR methods with filter in the
transmitter, 64QAM modulation in flat fading channel
Fig 19: DAR, IDAR and IDARF methods with and without
filter in the transmitter, 64QAM modulation in flat fading
channel, SNR=20 dB, N=256 subcarriers
CONCLUSIONS
When using the 16QAM modulation, DAR and IDAR have
similar performance when no filter is applied at the
transmitter, this performance is also very similar to that of
IDARF when the FFT filter is applied at the transmitter,
although IDARF performs slightly better. When the
modulation used is 64QAM, IDAR performs better than DAR
without filter at the transmitter and they both have similar
7. IJRET: International Journal of Research in Engineering and Technology eISSN: 2319-1163 | pISSN: 2321-7308
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Volume: 02 Issue: 09 | Sep-2013, Available @ http://www.ijret.org 285
behavior. IDARF, on the other hand, performs clearly better
than DAR and IDAR and its behavior is closer to the case
when no clipping is applied than to IDAR and DAR. When the
methods are analyzed for different clipping ratios, the
simulations show that when the filter is used in the transmitter
and for CR < 7 dB, IDARF performs better than all the other
methods, for higher CR they all perform the same. When
comparing all methods without filter in the receiver, IDARF
performs better than IDAR and DAR for CR < 4 dB, for
higher CR their performances are very similar. The filter is an
important element in OFDM systems since it reduces the out-
of-band radiation and ICI caused by clipping. As seen in the
simulations, when the filter is used in the transmitter, the
method that better performs in the receiver is IDARF.
Therefore, when clipping is applied, the better solution in
order to mitigate the noise that it introduces is to use the FFT
filter together with the IDARF method.
REFERENCES
[1] Jean Armstrong. “New OFDM Peak-to-average Reduction
Scheme”. In IEEE Vehicular Technology Conference, Rhodes,
Greece, 2001
[2] Pisit Boonsrimuang, Kazuo Mori, Tawil Paungma, and
Hideo Kobayashi. “Proposal of Clipping and Inter-modulation
Noise Mitigation Method for OFDM Signal in Non-linear
Channel”. IEICE Trans. Commun., 2005.
[3]Khaled Fazel and Stefan Kaiser. Multi-Carrier and Spread
Spectrum Systems. Wiley,2003.
[4]Hiroshi Harada and Ramjee Prasad. Simulation and
Software Radio for Mobile Communications.Artech House,
2003.
[5]Dukhyun Kim and Gordon L. Stuber. “Clipping Noise
Mitigation for OFDMby Decisionaided Reconstruction”. IEEE
Communication Letters, 1999.
[6]Xiaodong Li and Leonard J. Cimini. “Effects of Clipping
and Filtering on the Performance of OFDM”. IEEE
Communication Letters, 1998
[7]Ye (Geoffrey) Li and Gordon L. Stuber. Orthogonal
Frequency Division Multiplexing for Wireless
Communications. Springer, 2006.
[8]Ramjee Prasad. OFDM for Wireless Communication
Systems. Artech House, 2004
[9]Henrik Schulze and Christian Luders. Theroy and
Applications of OFDM and CDMA. Wideband Wireless
Communications. Wiley, 2003
[10]H. Sizun. Radio Wave Propagation for
Telecommunication Applications. Springer,2003
BIOGRAPHIES
Hemant Choubey, he has received the B.E.
degree in Electronics and communication
engineering from Rajiv Gandhi Technical
University Bhopal, in 2009. He is currently
pursuing M.E degree in Digital Communication
from RGTU Bhopal.