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.
The several assets for high-speed data transmission over wireless uses the Orthogonal Frequency Division
Multiplexing (OFDM) as it is a multicarrier transmission scheme. A large number of narrow bandwidth carriers is
therefore adopted by the OFDM. Individually for an OFDM, each subcarrier is attenuated under the frequency-selective
and fast fading channel, therefore the resulting gain is high attenuation which leads to poor performance of all OFDM
subcarriers if the same fixed transmission scheme are used. Thus the main goal of the indicated paper is to grab an
understanding of the inequality between fixed & adaptive modulations schemes as the introduction of the adaptive
modulation. The need for the above system is to make use of the speaker's voice to check their character and control
approach to administrations, for example, voice dialing data administrations, voice send, and security control for secret
data. The performance of paperwork basically states that implementation of adaptive modulation is done into blocks of
adjacent subcarriers which is the result of dividing whole subcarriers. Therefore the equivalent modulation scheme which
is the calculation of average instantaneous signal to noise (SNR) is exercised to entire subcarriers of the equal block. The
OFDM system average bit error rate (BER) performance is observed here under fixed modulation and adaptive
modulation, and these modulation techniques are recorded by accepting the different inverse fast Fourier transforms
(IFFT) size and uncomplicated adaptive Quadrature amplitude modulation (QAM) strategy. The simulation in MATLAB
shows the results as the performance of fixed modulation is inferior to that of the BER performance of OFDM system
using adaptive modulation. The prospective adaptive modulation and coding Technique uses OFDM to manage the fixed
BER under changing the channel.
Peak to Average Power Ratio (PAPR) Reduction in OFDM-OQAM Signalspaperpublications3
Abstract: The Orthogonal Frequency Division Multiplexing (OFDM) is a type of modulation that is being used for many of the latest wireless, telecommunication and broadcasting standards. OFDM is considered to be complicated than other signals but also it possess high data rate transmissions with relatively wide bandwidths. The major disadvantage included in OFDM signal is Peak-to-Average Power Ratio (PAPR) in higher level and Sensitive to Carrier offset. Hence there were found to be many reduction techniques for PAPR have been proposed where in need to reduction in high PAPR and carrier sensitivity still more to make it efficient for future optical domain standards. This paper not only makes the OFDM system advantageous but also suitable for fast data transmission and reduces the complication at receiver side, because all the transmitting data are cleared out of signal noise, interferences, etc. The technique which is going to get implemented for PAPR reduction is Optimized Iterative Clipping and Filtering (OICF).The OFDM is provided with the subcarrier of N=256 and the modulation of Offset Quadrature Amplitude Modulation (OQAM). The OQAM-OFDM provides the higher spectral efficiency and also the inter-symbol interference is avoided since not using Cyclic Prefix (CP) in OQAM-OFDM signal. The main reason for reducing PAPR is that to avoid non- linearity at the receiving end in high speed wireless communication.
The several assets for high-speed data transmission over wireless uses the Orthogonal Frequency Division
Multiplexing (OFDM) as it is a multicarrier transmission scheme. A large number of narrow bandwidth carriers is
therefore adopted by the OFDM. Individually for an OFDM, each subcarrier is attenuated under the frequency-selective
and fast fading channel, therefore the resulting gain is high attenuation which leads to poor performance of all OFDM
subcarriers if the same fixed transmission scheme are used. Thus the main goal of the indicated paper is to grab an
understanding of the inequality between fixed & adaptive modulations schemes as the introduction of the adaptive
modulation. The need for the above system is to make use of the speaker's voice to check their character and control
approach to administrations, for example, voice dialing data administrations, voice send, and security control for secret
data. The performance of paperwork basically states that implementation of adaptive modulation is done into blocks of
adjacent subcarriers which is the result of dividing whole subcarriers. Therefore the equivalent modulation scheme which
is the calculation of average instantaneous signal to noise (SNR) is exercised to entire subcarriers of the equal block. The
OFDM system average bit error rate (BER) performance is observed here under fixed modulation and adaptive
modulation, and these modulation techniques are recorded by accepting the different inverse fast Fourier transforms
(IFFT) size and uncomplicated adaptive Quadrature amplitude modulation (QAM) strategy. The simulation in MATLAB
shows the results as the performance of fixed modulation is inferior to that of the BER performance of OFDM system
using adaptive modulation. The prospective adaptive modulation and coding Technique uses OFDM to manage the fixed
BER under changing the channel.
Peak to Average Power Ratio (PAPR) Reduction in OFDM-OQAM Signalspaperpublications3
Abstract: The Orthogonal Frequency Division Multiplexing (OFDM) is a type of modulation that is being used for many of the latest wireless, telecommunication and broadcasting standards. OFDM is considered to be complicated than other signals but also it possess high data rate transmissions with relatively wide bandwidths. The major disadvantage included in OFDM signal is Peak-to-Average Power Ratio (PAPR) in higher level and Sensitive to Carrier offset. Hence there were found to be many reduction techniques for PAPR have been proposed where in need to reduction in high PAPR and carrier sensitivity still more to make it efficient for future optical domain standards. This paper not only makes the OFDM system advantageous but also suitable for fast data transmission and reduces the complication at receiver side, because all the transmitting data are cleared out of signal noise, interferences, etc. The technique which is going to get implemented for PAPR reduction is Optimized Iterative Clipping and Filtering (OICF).The OFDM is provided with the subcarrier of N=256 and the modulation of Offset Quadrature Amplitude Modulation (OQAM). The OQAM-OFDM provides the higher spectral efficiency and also the inter-symbol interference is avoided since not using Cyclic Prefix (CP) in OQAM-OFDM signal. The main reason for reducing PAPR is that to avoid non- linearity at the receiving end in high speed wireless communication.
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
Performance Analysis of Post Compensated Long Haul High Speed Coherent Optica...Yayah Zakaria
This paper addresses the performance analysis of OFDM transmission system based on coherent detection over high speed long haul optical links with high spectral efficiency modulation formats such as Quadrature Amplitude Modulation (QAM) as a mapping method prior to the OFDM multicarrier representation. Post compensation is used to compensate for
phase noise effects. Coherent detection for signal transmitted at bit rate of 40 Gbps is successfully achieved up to distance of 3200km. Performance is analyzed in terms of Symbol Error Rate and Error Vector Magnitude by varying Optical Signal to Noise Ratio (OSNR) and varying the length of the fiber i.e transmission distance. Transmission performance is also observed through constellation diagrams at different transmission distances and
different OSNRs.
Performance Analsis of Clipping Technique for Papr Reduction of MB-OFDM UWB S...ijcisjournal
Multiband Orthogonal Frequency Division Multiplexing (MB-OFDM) is used as efficacious procedure for
ultra-wideband (UWB) wireless communication applications, which divides the spectrum into various subbands,
whose bandwidth is approximately 500MHz. Major arduousness in multiband-OFDM is ,it have
very large peak to average power ratio value which causes the signal to enter into dynamic region that
consequence in the loss of orthogonal properties and results in the interference of the carrier signals which
crops the amplifier saturation and finally limits the capacity of the system. Many PAPR amortize
algorithms have reported in the survey and pre-coding is PAPR reduction which is inserted after
modulation in the OFDM system. The Existing work presents the reduction of that value by different
clipping techniques namely Classical-Clipping (CC), Heavy side-Clipping (HC), Deep-Clipping (DC) and
Smooth-Clipping (SC) and their comparison analysis is done. Every clipping method is best at its own
level .The proficiency of these strategies are evaluated in locutions of average power disparity, complete
system decadence and PAPR reduction. Finally results show the MB OFDM yields better performance to
reduce PAPR in effective way.
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
Spectrum sensing is an essential concept in cognitive radio. It exploits the inefficient utilization
of radio frequency spectrum without causing destructive interference to the licensed users. In
this paper we considered spectrum sensing of Digital Video Broadcast Terrestrial (DVB-T)
signal in different scenario. We compared various spectrum sensing algorithms that make use of
the second order statistics; the energy detector was also included for comparison. The results
show that it is possible to obtain good detection performance by exploiting the correlation
method.
Analysis of Simulation Parameters of Pulse Shaping FIR Filter for WCDMAijsrd.com
The application of signal processing techniques to wireless communications is an emerging area that has recently achieved dramatic improvement in results and holds the potential for even greater results in the future as an increasing number of researchers from the signal process and communications areas participate in this expanding field. From an industrial viewpoint also, the advanced signal processing technology cannot only dramatically increase the wireless system capacity but can also improve the communication quality including the reduction of all types of interference. The present paper deals with simulation model of square root raised cosine pulse shaping filter for WCDMA with different parameters of the filter at 5Mhz.The present paper deals with study of Simulation Parameters (Number of Bits, Number of Errors) of Pulse Shaping FIR Filter at different value of group delay(2,4,6,8) to the calculate BER for WCDMA.
This includes Digital signal data transmission, Base band and band pass transmission. Also detailed with PAM, PPM, PWM, PCM, DPCM, DM, ADM, ASK, PSK, FSK.
this lecture provide the different features of pulse code modulation it explains the concept using example and explained step by step shows the flat sampling and other type shows the advantage of pam provides the pcm system block diagram a brief introduction about delta modulation
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
Performance Analysis of Post Compensated Long Haul High Speed Coherent Optica...Yayah Zakaria
This paper addresses the performance analysis of OFDM transmission system based on coherent detection over high speed long haul optical links with high spectral efficiency modulation formats such as Quadrature Amplitude Modulation (QAM) as a mapping method prior to the OFDM multicarrier representation. Post compensation is used to compensate for
phase noise effects. Coherent detection for signal transmitted at bit rate of 40 Gbps is successfully achieved up to distance of 3200km. Performance is analyzed in terms of Symbol Error Rate and Error Vector Magnitude by varying Optical Signal to Noise Ratio (OSNR) and varying the length of the fiber i.e transmission distance. Transmission performance is also observed through constellation diagrams at different transmission distances and
different OSNRs.
Performance Analsis of Clipping Technique for Papr Reduction of MB-OFDM UWB S...ijcisjournal
Multiband Orthogonal Frequency Division Multiplexing (MB-OFDM) is used as efficacious procedure for
ultra-wideband (UWB) wireless communication applications, which divides the spectrum into various subbands,
whose bandwidth is approximately 500MHz. Major arduousness in multiband-OFDM is ,it have
very large peak to average power ratio value which causes the signal to enter into dynamic region that
consequence in the loss of orthogonal properties and results in the interference of the carrier signals which
crops the amplifier saturation and finally limits the capacity of the system. Many PAPR amortize
algorithms have reported in the survey and pre-coding is PAPR reduction which is inserted after
modulation in the OFDM system. The Existing work presents the reduction of that value by different
clipping techniques namely Classical-Clipping (CC), Heavy side-Clipping (HC), Deep-Clipping (DC) and
Smooth-Clipping (SC) and their comparison analysis is done. Every clipping method is best at its own
level .The proficiency of these strategies are evaluated in locutions of average power disparity, complete
system decadence and PAPR reduction. Finally results show the MB OFDM yields better performance to
reduce PAPR in effective way.
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
Spectrum sensing is an essential concept in cognitive radio. It exploits the inefficient utilization
of radio frequency spectrum without causing destructive interference to the licensed users. In
this paper we considered spectrum sensing of Digital Video Broadcast Terrestrial (DVB-T)
signal in different scenario. We compared various spectrum sensing algorithms that make use of
the second order statistics; the energy detector was also included for comparison. The results
show that it is possible to obtain good detection performance by exploiting the correlation
method.
Analysis of Simulation Parameters of Pulse Shaping FIR Filter for WCDMAijsrd.com
The application of signal processing techniques to wireless communications is an emerging area that has recently achieved dramatic improvement in results and holds the potential for even greater results in the future as an increasing number of researchers from the signal process and communications areas participate in this expanding field. From an industrial viewpoint also, the advanced signal processing technology cannot only dramatically increase the wireless system capacity but can also improve the communication quality including the reduction of all types of interference. The present paper deals with simulation model of square root raised cosine pulse shaping filter for WCDMA with different parameters of the filter at 5Mhz.The present paper deals with study of Simulation Parameters (Number of Bits, Number of Errors) of Pulse Shaping FIR Filter at different value of group delay(2,4,6,8) to the calculate BER for WCDMA.
This includes Digital signal data transmission, Base band and band pass transmission. Also detailed with PAM, PPM, PWM, PCM, DPCM, DM, ADM, ASK, PSK, FSK.
this lecture provide the different features of pulse code modulation it explains the concept using example and explained step by step shows the flat sampling and other type shows the advantage of pam provides the pcm system block diagram a brief introduction about delta modulation
É dito a tempos que “a ocasião faz o ladrão”, e é inegável a verossimilhança do ditado, mas seria, no caso brasileiro, só a ocasião de ser uma pessoa política, a razão real da corrupção? Para responder a essa pergunta, iremos primeiramente definir: O que é corrupção? Corrupção (do latim: Corruptus – “despedaçado”, ou em uma segunda acepção, “pútrido”) é o ato de se corromper, ou seja, obter vantagem indevida, seja por ação ou omissão, observando-se a satisfação de benefício próprio, a despeito do bem comum. Ao contrário do saber popular, a corrupção não é só política, e nem sempre envolve dinheiro. Existem três formas de se corromper: pelo abuso, pela omissão ou pelo desvio. O abuso, que é tido como normal pela sociedade brasileira hierarquizada pode ser representado pela frase: “Você sabe com quem está falando?”. Trata-se de um traço autoritário da sociedade brasileira. Ela funciona para demarcar diferenças e posições hierárquicas. O seu uso pode ser traduzido como "me respeite, pois não sou do seu nível", ou, melhor ainda, "nós não somos iguais". A partir da famosa frase de Maquiavel: “Favori agli amici, nemici della legge” (Aos amigos favores, aos inimigos a lei), representa bem esse abuso, de um poder que deveria servir para a manutenção do bem comum, e é usado, na verdade,
GUIA DO ELEITOR PARA VOTAR CONCIENTE
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Una comunidad de práctica y aprendizaje abierta, gratuita y colaborativa
Impact of Clipping and Filtering on Peak to Average Power Ratio of OFDM Systemijsrd.com
Orthogonal Frequency Division Multiplexing (OFDM) is an emerging field of research in the field of 4G broadband wireless communications due to its robustness against multipath fading and relatively simple implementation. Peak to Average Power Ratio (PAPR) is the limiting factor for an OFDM system as it consists of large number of independent subcarriers as a result of which the amplitude of such a signal can have high peak values which degrades the system performance. Such a signal when amplified by a Power Amplifier without processing results spectral regrowth and intermodulation among subcarrier. Hence this non linearity destroys the orthogonally of the OFDM signal and introduces out-of-band radiation and in band distortions causing significant performance degradation. The clipping and filtering method is analysed which is an efficient and simple method to reduce the PAPR. We have shown the effects of clipping and filtering on the performance of OFDM, including the power spectral density, the crest factor, and the bit-error rate.
Comparative performance analysis of different modulation techniques for papr ...IJCNCJournal
One of the most important multi-carrier tran
smission techniques used in the latest wireless com
munication
arena is known as Orthogonal Frequency Division Mul
tiplexing (OFDM). It has several characteristics
such as providing greater immunity to multipath fad
ing & impulse noise, eliminating Inter Symbol
Interference (ISI) & Inter Carrier Interference (IC
I) using a guard interval known as Cyclic Prefix (C
P). A
regular difficulty of OFDM signal is high peak to a
verage power ratio (PAPR) which is defined as the r
atio
of the peak power to the average power of OFDM Sign
al. An improved design of amplitude clipping &
filtering technique of us previously reduced signif
icant amount of PAPR with slightly increase bit err
or rate
(BER) compare to an existing method in case of Quad
rature Phase Shift Keying (QPSK) & Quadrature
Amplitude Modulation (QAM). This paper investigates
a comparative performance analysis of the differen
t
higher order modulation techniques on that design.
AN OVERVIEW OF PEAK-TO-AVERAGE POWER RATIO REDUCTION TECHNIQUES FOR OFDM SIGNALSijmnct
OFDM (Orthogonal Frequency Division Multiplexing) has been widely adopted for high data rate wireless
communication systems due to its advantages such as extraordinary spectral efficiency, robustness to
channel fading and better QoS (Quality of Service) performance for multiple users. However, some
challenging issues are still unresolved in OFDM systems. One of the issues is the high PAPR (peak-toaverage
power ratio), which results in nonlinearity in power amplifiers, and causes out of band radiation
and in band distortion. This paper reviews some conventional PAPR reduction techniques and their
modifications to achieve better PAPR performance. Advantages and disadvantages of each technique are
discussed in detail. And comparisons between different techniques are also presented. Finally, this paper
makes a prospect forecast about the direction for further researches in the area of PAPR reduction for
OFDM signals
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.
A Hybrid PAPR Reduction Scheme for OFDM System ijmnct
Orthogonal frequency division multiplexing (OFDM) i
s considered as most efficient technique for future
wireless communication systems due to its higher sp
ectral bandwidth efficiency, robustness to frequenc
y
selective fading channels, etc. However, the succes
sful implementation of the OFDM system necessitates
several difficulties. The biggest disadvantage to w
ork with OFDM system is its high peak-to-average po
wer
ratio PAPR leadsto severe inter carrier interferenc
e, out-of-band radiation, and poor bit error rate
performance due to the nonlinearity of the high pow
er amplifier. In this paper, a novel hybrid techniq
ue is
proposed to reduce PAPR further and comparison has
been done with conventional techniques as well.
Simulated results are presentedconfirm theoretical
results.MATLAB 7.5 is used to simulate the results
for system parametersconsidered.
A review paper on the papr analysis of orthogonal frequency division multiple...ijmnct
OFDM (Orthogonal Frequency Division Multiplexing) has been raised a new modulation technique. Due
to its advantages in multipath fading channel e.g. robust against ISI, ICI and some other advantages like
best QoS for multiple users, efficient usage of bandwidth it is suggested to be the modulation technique for
next generation 4G networks e.g. LTE. But along with all its advantages there are some disadvantages also
e.g. High PAPR (Peak to Average Power Ratio) at the transmitter end and BER (Bit Error Rate) at the
receiving end. Since OFDM is only used in the downlink of 4G networks. To reduce the problems of OFDM
some techniques e.g. SLM, PTS, Clipping, Coding, & Pre-coding etc are suggested but none of them is
reduce the PAPR and BER to an acceptable value. This Paper will discuss some techniques of PAPR &
BER reduction, and their advantages and disadvantages in detail.
International Journal of Engineering Research and Applications (IJERA) is a team of researchers not publication services or private publications running the journals for monetary benefits, we are association of scientists and academia who focus only on supporting authors who want to publish their work. The articles published in our journal can be accessed online, all the articles will be archived for real time access.
Our journal system primarily aims to bring out the research talent and the works done by sciaentists, academia, engineers, practitioners, scholars, post graduate students of engineering and science. This journal aims to cover the scientific research in a broader sense and not publishing a niche area of research facilitating researchers from various verticals to publish their papers. It is also aimed to provide a platform for the researchers to publish in a shorter of time, enabling them to continue further All articles published are freely available to scientific researchers in the Government agencies,educators and the general public. We are taking serious efforts to promote our journal across the globe in various ways, we are sure that our journal will act as a scientific platform for all researchers to publish their works online.
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.
PAPR Reduction in OFDM using New Hybrid Techniquesijtsrd
With the advancement in age and its growing demands, there has been fast production in the field of communication system. Signals, which were sent at the beginning in the analog form, are being sent more and more in the digital form now in these days. For improved transmission, even single carrier waves are being recouped by multi carriers' waves. Multi carrier systems like CDMA and OFDM are now a days being implemented commonly. In the OFDM system, orthogonally placed subcarriers are used to send the data from the transmitter end to the receiver end. Presence of guard band in this communication system deals with the ISI issues and noise is mitigated by larger number of sub carriers. But the large PAPR Peak to Average Power Ratio of these signals have some unsuitable effects on the communication system. In this research work we have focused on the OFDM System and have implemented various techniques to reduce the PAPR in the OFDM system so that this system can be used more commonly and energetically. Vikas kumar | Preeti Sondhi "PAPR Reduction in OFDM using New Hybrid Techniques" Published in International Journal of Trend in Scientific Research and Development (ijtsrd), ISSN: 2456-6470, Volume-3 | Issue-5 , August 2019, URL: https://www.ijtsrd.com/papers/ijtsrd27820.pdf Paper URL: https://www.ijtsrd.com/engineering/other/27820/papr-reduction-in-ofdm-using-new-hybrid-techniques/vikas-kumar
BER Performance of OFDM-QAM over AWGN and RICAIN Channels Using Error Correct...IJERA Editor
In this paper, the performance of OFDM - QAM system by using error correcting codes (Convolutional, Reed Solomon and Interleaving) schemes that are used to encode the data stream in wireless communications using AWGN and RICIAN channels has been reported here. OFDM is presented for wireless communications we curing basic OFDM and affined modulations, as well as techniques to improve the performance of OFDM for wireless communications. Various simulations are performed to detect the best BER performance of each of the QAM system; OFDM-QAM and OFDM-QAM with Error Correction and to use the best outcomes to model the OFDM-QAM, Their effect of improving the total BER can be noticed due to the benefits of OFDM-QAM with correcting codes.
A low complexity partial transmit sequence scheme for better papr reduction i...eSAT Journals
Abstract The main drawback of OFDM system is the high Peak to Average Power Ratio (PAPR) of the transmitted signals. Partial transmit sequence scheme is a promising algorithm to reduce the peak-to-average power ratio (PAPR) in orthogonal frequency division multiplexing (OFDM). The Partial Transmit Sequence (PTS) consist of several inverse fast Fourier transform (IFFT) operations and complicated calculations to obtain optimum phase sequence which results in increasing the computational complexity of PTS. A phase sequence applied to the PTS Scheme reduces its complexity but at the expense of slight degradation in PAPR reduction. In this paper, for further reduction of PAPR the peak clipping of the OFDM signal is introduced along with the PTS with new phase sequence scheme. Since clipping is one of the simplest techniques of PAPR reduction, it does not increase the complexity of the system much and a better PAPR reduction is obtained with the combined effect of clipping and PTS with New Phase Sequence. But the clipping technique introduce some distortion in the signal, however peak clipping of signal below a particular threshold can maintain the BER in the tolerable range. The clipping threshold selected will be different for different OFDM systems. Index Terms: OFDM, Peak to Average Power Ratio (PAPR), Partial Transmit Sequence (PTS), Clipping.
Orthogonal frequency-division multiplexing (OFDM)
[1] is a method of encoding digital data on multiple carrier
frequencies. OFDM[1] has developed into a popular scheme
for wideband digital communication, whether wireless or
over copper wires, used in applications such as digital television
and audio broadcasting, DSL Internet access, wireless networks,
powerline networks, and 4G mobile communications. In the
Several wireless standards such as IEEE 802.11a[2] and
HiperLAN2[3].The orthogonality of the subcarriers is no longer
maintained which results in ICI (Inter carrier Interference)[4]
.ICI reduction techniques achieve a better SNR and BER in
OFDM at zero phase noise variance . This technique will use a
large number of closely spaced orthogonal subcarriers to avoid
phase noise. It provides high data rates with sufficient robustness
to radio channel damages. A major problem in OFDM is carrier
frequency offset error between the transmitted and received
signals. Due to this the orthogonality of the subcarriers is no
longer maintained which results in ICI (Inter carrier
Interference). In this paper, we used the ICI self-cancellation
technique and reduced the ICI and improved the BER and SNR
we are also calculate the SNR=15db and 20db at different phase
noise variance.
Similar to Adaptive Clipping for PAPR Reduction in OFDM (20)
Final project report on grocery store management system..pdfKamal Acharya
In today’s fast-changing business environment, it’s extremely important to be able to respond to client needs in the most effective and timely manner. If your customers wish to see your business online and have instant access to your products or services.
Online Grocery Store is an e-commerce website, which retails various grocery products. This project allows viewing various products available enables registered users to purchase desired products instantly using Paytm, UPI payment processor (Instant Pay) and also can place order by using Cash on Delivery (Pay Later) option. This project provides an easy access to Administrators and Managers to view orders placed using Pay Later and Instant Pay options.
In order to develop an e-commerce website, a number of Technologies must be studied and understood. These include multi-tiered architecture, server and client-side scripting techniques, implementation technologies, programming language (such as PHP, HTML, CSS, JavaScript) and MySQL relational databases. This is a project with the objective to develop a basic website where a consumer is provided with a shopping cart website and also to know about the technologies used to develop such a website.
This document will discuss each of the underlying technologies to create and implement an e- commerce website.
Hybrid optimization of pumped hydro system and solar- Engr. Abdul-Azeez.pdffxintegritypublishin
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Adaptive Clipping for PAPR Reduction in OFDM
1. Vinaykumar S.Nagalikar. Int. Journal of Engineering Research and Application www.ijera.com
ISSN : 2248-9622, Vol. 7, Issue 2, ( Part -6) February 2017, pp.06-09
www.ijera.com DOI: 10.9790/9622- 0702020609 6 | P a g e
Adaptive Clipping for PAPR Reduction in OFDM
Vinaykumar S.Nagalikar1
, Uday Pandit Khot2
1
Electronics and telecommunication, St.Xavier’s Technical Institute, Mumbai, India
2
Uday Pandit Khot, Member IEEE, Professor, Electronics and Telecommunication Engineering Department,
Borivali, Mumbai, India
ABSTRACT
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.
Keywords: BER ,OFDM, PAPR.
I. INTRODUCTION
THE OFDM transmission Technique is a
successful technique for high speed Data
communication in wireless environment. Due to its
orthogonal property the interference between the
subcarriers is reduced. Frequency division
multiplexing allows a single high rate data to be
broken in to various low speed data rates which
mitigate the fading of the signal [1]. OFDM is
extensively used in the data communication in
Wireless applications such as wireless LAN, 4G,
WIMAX, Digital (DVB) etc. The main drawback of
the OFDM system is the High Peak to Average
power ratio (PAPR). High PAPR results due to high
change of magnitude and phase of the adjacent
carriers and inability of the High power amplifier
(HPA) to cope up with these along maintaining high
efficiency. The non-linearity of the HPA would
distort the OFDM signals; hence on the expense of
efficiency non linearity of the amplifier is avoided.
The OFDM transmission is a multi-carrier
transmission system and has a several advantages
compared to single carrier. In OFDM several carrier
signals of lower data rates run parallel. To avoid
inter carrier interference the carrier are orthogonally
transmitted. Each sub-carrier is modulated with
digital modulation techniques such as (BPSK, QAM,
and PSK ETC). The main advantages of OFDM
signals are that they overcome channel conditions
like interference in the signal. Frequency selective
fading is overcome because the OFDM signal
consists of several sun-carriers of different
frequencies. Multipath fading is also overcome. The
guard interval also helps the signal to provide
spacing between the subcarriers. The OFDM signal
is robust against narrow band co channel
interference. Thus the OFDM signals are sensitive to
the Frequency synchronization problems. The
signals are also sensitive to Doppler shift. The major
disadvantage is high Peak to average Power ratio
(PAPR). High PAPR causes the HPA (High power
amplifier) to go in to non-linear region of HPA
which causes distortions in the signals [2]. Hence
methods have been developed to overcome the high
PAPR problem.
Several techniques are available for
reducing PAPR among them which are commonly
used for the practical is given in [3]-[6]. Inter carrier
interference (ICI) is overcome by orthogonal signals,
placing the modulated carriers closely increases the
spectral efficiency of the OFDM system [6].
The clipping method is the simplest of all
and is used extensively. In this method the signal
above the fixed threshold is clipped so as to reduce
PAPR. Clipping process generates in band and out
of band distortion. To mitigate the distortion caused
by clipping filtering technique is used after clipping.
In filtering technique, convolution of the signal is
performed. Clipping and filtering is widely used
methods for reducing PAPR. To achieve low PAPR
further iterative clipping and filtering has been
proposed in [7].
This paper gives adaptive clipping where
the threshold value of clipping is adapted according
to the magnitude of the signals and is not always
fixed. The time-domain representation of an OFDM
symbol with N subcarriers can be represented as
follows:
RESEARCH ARTICLE OPEN ACCESS
2. Vinaykumar S.Nagalikar. Int. Journal of Engineering Research and Application www.ijera.com
ISSN : 2248-9622, Vol. 7, Issue 2, ( Part -6) February 2017, pp.06-09
www.ijera.com DOI: 10.9790/9622- 0702020609 7 | P a g e
…………………………. (1)
where Ts is the duration of an OFDM signal, and fk =
k
Here, all carriers are modulated with a single
modulation technique. The N is the number of sub
carriers.
II. PEAK AVERAGE POWER RATIO
PAPR is the most significant problem in
multi-carrier system. Several methods have been
developed to overcome high PAPR. The PAPR
reduction methods like clipping and filtering,
selective mapping, coding, companding,
probabilistic methods have been introduced The
PAPR reductions techniques have a trade-off
between reducing PAPR and reducing BER (Bit
error rate).
The PAPR of the OFDM signal is given by
………(2)
III. SYSTEM MODEL
A block representation of an OFDM system
[3] is shown in Fig 1. An OFDM system starts with
the input of data stream from the communication
device. The input data stream is in binary format ‟0‟
and „1‟. The data is modulated using any modulation
sachem such as BPSK, QPSK, and QAM etc...
Fig 1. OFDM Block diagram representation
In our simulation QAM modulation is used.
Accordingly the scatter plot is drawn. Then the data
is transformed in to time domain using IFFT
operation. The IFFT values are complex numbers
indicating the phase and amplitude of the signal. The
pilot signals are inserted according. Zero padding is
used as a guard interval between the signals. The
adaptive of the clipping is determined by the number
of peaks exceeding the predetermined number, in
which case if the peaks exceed then they are clipped
at 10% of its value. The flow chart of the adaptive
algorithm is shown below The OFDM
communication is shown in the block diagram
below. The data to be transmitted is in serial stream.
The data is first broken down to N parallel stream as
to match with the number of symbols. Again the
symbols are broken down in to corresponding
alphabet size for the modulation of the data. The
modulation scheme such as (BPSK, QPSK, QAM,
and PSK) is performed on the bits and constellation
chart is prepared and are matched with this chart.
The carriers can be modulated with multiple
modulation schemes, so the alphabet size of the sub-
carrier varies according with the modulation scheme
used [7].
The Inverse Fast Fourier Transform (IFFT)
is performed on each set of symbols to get a time
domain signal. In IFFT operation frequency domain
signals are converted in to time domain signal by
Discrete Fourier Transform (DFT). The IFFT signal
is composed of Real and Imaginary parts. The Guard
signals are inserted between the carriers to avoid
interference between the sub carriers. The pilot
signals are placed strategically in between the sub
carrier to read the channel conditions and estimate
the channel conditions.
The clipping of the Signal takes place to
reduce PAPR. The Adaptive clipping technique is
explained in detail in the next part. The Filtering of
the signal is performed to reduce in band and out of
band distortion during the clipping process. This is
done by simply taking the Convolution of the signal.
Then cyclic prefix is performed on the data stream
for error checking. The OFDM is passed through a
wireless channel and various types of noises get
added with the signal [8].
OFDM Transmission is accepted world
wide for high speed dta transmission and
applications,Due to its increased use fine tunning of
the ofdm signals are required to overcome its some
of its drawbacks.the important of all is Peak to
average power ratio
3. Vinaykumar S.Nagalikar. Int. Journal of Engineering Research and Application www.ijera.com
ISSN : 2248-9622, Vol. 7, Issue 2, ( Part -6) February 2017, pp.06-09
www.ijera.com DOI: 10.9790/9622- 0702020609 8 | P a g e
IV. PROPOSED ADAPTIVE CLIPPING
TECHNIQUE
The flow chart shown in Fig. 2 explains proposed
adaptive method for PAPR reduction.
Fig. 2 The Flow Chart of Adaptive Clipping
In adaptive clipping technique, the number
of the highest peaks among the signal is calculated
then decision is taken to whether clip the signal or
not. In contrast to clipping technique which clips the
signal at 70% of the maximum value which results
in high BER. As shown in the algorithm, first the
signals are checked for the highest amplitude, then
the signals around Adaptive clipping is very much
helpful when the peaks in the signals are too many.
Clipping the signals would result to considerably
loss of signal and high error rate. Adaptive clipping
in the other hand first checks for the number of
peaks and then decision is taken to whether clip or
not to clip.
If clipping is to be performed then at what
level the signal is to be clipped so that there is no
considerably loss of signal is calculated. Then the
signal is clipped in such a way so as to maintain low
PAPR in the signal. The clipping of the signal is
done by the following method carefully. Firstly the
highest peak in the ofdm signal is calculated, then
10% of that value is searched. If the
number of the signals under the 10% of the max
value is under 5% in terms of N then the signal is
clipped to 10% of the highest amplitude. Here some
information is lost due to clipping but the PAPR is
maintained as a good level. In other case if the
signals are more than 5% then the signals are not
clipped so as to retain the information in the signal.
Here PAPR in this case may be high.
At the receiver side exact reverse operation
takes place and the data is extracted back.For a
particular set of signals the adaptive clipping have a
less BER compared to Clipping. If the number of
peaks are high then the adaptive clipping offers less
BER. This happens because the clipping threshold
has been kept only at 10% of the signals. If the
signals are above the 10% value then the signals are
not clipped to avoid significant loss of the signal.
Adaptive clipping further helps in the
reduction of PAPR and improves BER. The
comparison between the Clipping and adaptive
clipping is done and the results are simulated in the
MATLAB software.
V. CONCLUSIONS
The proposed Adaptive Clipping is more
efficient than selective clipping method. The
adaptive technique first checks whether the signal
has to be clipped or not on the basis of the
information loss in the signal. This results in
improved BER. The adaptive nature of clipping is
thus proved beneficial and can be used for OFDM
transmission system. Adaptive clipping offers nearly
half a dB reduction compared to selective clipping.
With proposed technique, PAPR of 3 dB is obtained
with BER of 10-4
. The reductions in PAPR with
improved BER have been verified for number of
runs of Adaptive and selective clipping.
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www.ijera.com DOI: 10.9790/9622- 0702020609 9 | P a g e
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