The growth of wireless communication technologies has been producing the intense demand for high-speed,
efficient, reliable voice & data communication. As a result, third generation partnership project (3GPP)
has implemented next generation wireless communication technology long term evolution (LTE) which is
designed to increase the capacity and speed of existing mobile telephone & data networks. LTE has
adopted a multicarrier transmission technique known as orthogonal frequency division multiplexing
(OFDM). OFDM meets the LTE requirement for spectrum flexibility and enables cost-efficient solutions for
very wide carriers. One major generic problem of OFDM technique is high peak to average power ratio
(PAPR) which is defined as the ratio of the peak power to the average power of the OFDM signal. A
trade-off is necessary for reducing PAPR with increasing bit error rate (BER), computational complexity or
data rate loss etc. In this paper, two clipping based filtering methods have been implemented & also
analyzed their modulation effects on reducing PAPR.
A modified design of acf operation for reducing papr of ofdm signalijngnjournal
Next generation wireless communication technology long term evolution (LTE) has implemented
orthogonal frequency division multiplexing (OFDM) technique as a strong candidate for radio access
systems. It has several attributes such as providing robustness to multipath fading & impulse noise,
eliminating intersymbol interference (ISI), inter carrier interference (ICI) & the need for equalizers. The
major challenging issue of OFDM technique is the high peak to average power ratio (PAPR) which is
defined as the ratio of the peak power to the average power of the OFDM signal. A trade-off is
necessary for reducing PAPR with increasing bit error rate (BER), computational complexity or data rate
loss etc. In this paper, a moderately modified design of amplitude clipping & filtering operation (ACF) is
proposed and implemented which shows the significant improvement in case of PAPR reduction for both
quadrature phase shift keying (QPSK) & quadrature amplitude modulation (QAM) while increasing slight
BER match up to to an existing method.
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.
A Review Paper on: The PAPR Analysis of MIMO-OFDM SystemsIJEEE
Orthogonal frequency division Multiplexing (OFDM) is one of the most popular multicarrier or multiplexing modulation techniques which transmits many signals over a single path in high speed wireless communication. OFDM convert high data rate stream in to smaller data rate stream. Due to this high data rate and ability to combat frequency selective fading, OFDM has a strong candidate for 4G wireless networks. Because of OFDM-MIMO advantages in multipath fading channel e.g. stout against ISI, ICI and some other advantages like best QoS for multiple users, efficient convention of bandwidth it is suggested to be the modulation technique for next generation 4G networks e.g. LTE. OFDM combined with multiple-input multiple-output (MIMO) to increase system capacity over the time variant frequency-selective channels and the diversity gain. The radio transmitter stations for covering and getting enough transmitted power in their desired area has to use High Power Amplifier (HPA) operable near to the saturation region or else, an aspect memory-less nonlinear distortion will affect the communication path. 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. As OFDM is only used in the downlink of 4G networks. To reduce the problems of OFDM-MIMO systems some procedures as SLM, PTS, Clipping, Coding, & Pre-coding etc are suggested but none of them is proficient enough to reduce the PAPR and BER up to standard value. This Paper will discuss some techniques of PAPR reduction, and both their advantages and disadvantages.
SLM-PTS BASED PAPR REDUCTION TECHNIQUES IN OFDM SYSTEMHariniChaganti1
Signals, which were initially sent in the analog domain, are being sent more and more in the digital domain these days. For better transmission, even single–carrier waves are being replaced by multi–carriers. Multi-carrier
systems like OFDM are now – a – days being implemented commonly. In the OFDM system,
orthogonally placed subcarriers are used to carry the data from the transmitter end to the receiver end. The presence of a guard band in this system deals with the problem of ISI and noise is minimized by a larger number of sub–carriers. But the large Peak– to –Average Power Ratio of these signal have some undesirable effects on the system. The Peak-to-Average Power Ratio is the ratio between the maximum power and average power of a complex passband signal. It causes many disadvantages like band-in and band-out variation, low signal to quantization noise ratio, low efficiency of power amplifier, etc. Hence, it is necessary to reduce PAPR in OFDM for its efficient use.
In this project, the main objective is to study the basics of an OFDM System and analyze and
simulate various methods such as clipping and filtering, selected mapping, Partial transmit sequence
to reduce the PAPR in the system and compare these techniques with and without PAPR reduction to
obtain an efficient technique so that this system can be used more commonly and effectively.
A modified design of acf operation for reducing papr of ofdm signalijngnjournal
Next generation wireless communication technology long term evolution (LTE) has implemented
orthogonal frequency division multiplexing (OFDM) technique as a strong candidate for radio access
systems. It has several attributes such as providing robustness to multipath fading & impulse noise,
eliminating intersymbol interference (ISI), inter carrier interference (ICI) & the need for equalizers. The
major challenging issue of OFDM technique is the high peak to average power ratio (PAPR) which is
defined as the ratio of the peak power to the average power of the OFDM signal. A trade-off is
necessary for reducing PAPR with increasing bit error rate (BER), computational complexity or data rate
loss etc. In this paper, a moderately modified design of amplitude clipping & filtering operation (ACF) is
proposed and implemented which shows the significant improvement in case of PAPR reduction for both
quadrature phase shift keying (QPSK) & quadrature amplitude modulation (QAM) while increasing slight
BER match up to to an existing method.
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.
A Review Paper on: The PAPR Analysis of MIMO-OFDM SystemsIJEEE
Orthogonal frequency division Multiplexing (OFDM) is one of the most popular multicarrier or multiplexing modulation techniques which transmits many signals over a single path in high speed wireless communication. OFDM convert high data rate stream in to smaller data rate stream. Due to this high data rate and ability to combat frequency selective fading, OFDM has a strong candidate for 4G wireless networks. Because of OFDM-MIMO advantages in multipath fading channel e.g. stout against ISI, ICI and some other advantages like best QoS for multiple users, efficient convention of bandwidth it is suggested to be the modulation technique for next generation 4G networks e.g. LTE. OFDM combined with multiple-input multiple-output (MIMO) to increase system capacity over the time variant frequency-selective channels and the diversity gain. The radio transmitter stations for covering and getting enough transmitted power in their desired area has to use High Power Amplifier (HPA) operable near to the saturation region or else, an aspect memory-less nonlinear distortion will affect the communication path. 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. As OFDM is only used in the downlink of 4G networks. To reduce the problems of OFDM-MIMO systems some procedures as SLM, PTS, Clipping, Coding, & Pre-coding etc are suggested but none of them is proficient enough to reduce the PAPR and BER up to standard value. This Paper will discuss some techniques of PAPR reduction, and both their advantages and disadvantages.
SLM-PTS BASED PAPR REDUCTION TECHNIQUES IN OFDM SYSTEMHariniChaganti1
Signals, which were initially sent in the analog domain, are being sent more and more in the digital domain these days. For better transmission, even single–carrier waves are being replaced by multi–carriers. Multi-carrier
systems like OFDM are now – a – days being implemented commonly. In the OFDM system,
orthogonally placed subcarriers are used to carry the data from the transmitter end to the receiver end. The presence of a guard band in this system deals with the problem of ISI and noise is minimized by a larger number of sub–carriers. But the large Peak– to –Average Power Ratio of these signal have some undesirable effects on the system. The Peak-to-Average Power Ratio is the ratio between the maximum power and average power of a complex passband signal. It causes many disadvantages like band-in and band-out variation, low signal to quantization noise ratio, low efficiency of power amplifier, etc. Hence, it is necessary to reduce PAPR in OFDM for its efficient use.
In this project, the main objective is to study the basics of an OFDM System and analyze and
simulate various methods such as clipping and filtering, selected mapping, Partial transmit sequence
to reduce the PAPR in the system and compare these techniques with and without PAPR reduction to
obtain an efficient technique so that this system can be used more commonly and effectively.
Performance Evaluation of PAPR Reduction with SER and BER by Modified Clippin...ijcsse
This paper work focuses on performance analysis of PAPR reduction of orthogonal frequency division multiplexing (OFDM) using amplitude clipping & filtering based design. Now a days one of the most proficient multi-carrier transmission techniques widely used today is orthogonal frequency division multiplexing (OFDM) which has been implemented by the next generation wireless communication technology: Long Term Evolution (LTE). Extra robustness to multipath fading and impulse noise is provided OFDM. It eliminates inter symbol interference (ISI) & inter carrier interference (ICI) with certain procedure. Therefore peak to average power ratio (PAPR) is the basic problem with OFDM. However in this paper we proposed a reduction procedure of the PAPR by using clipping and filtering. Here we use a composed high pass , low pass & Chevyshev band pass filter II after amplitude clipping to reduce the PAPR. The performance of the system in terms of bit error rate (BER) and symbol error rate (SER) is also investigated as a new filter based clipping method is proposed. Our proposed clipping method with and composed high pass the Chevyshev bandpass filter II in PAPR performance of the system with a little compromise of BER & SER showing the significant improvement in Quadrature Amplitude Modulation (QAM).
Reducing the Peak to Average Power Ratio of Mimo-Ofdm SystemsIJCNCJournal
In this paper, we proposed a particle swarm optimization (PSO) based partial transmit sequence (PTS)
technique in order to achieve the lowest Peak-to-Average Power Ratio(PAPR) in Multiple Input Multiple
Output- Orthogonal Frequency Division Multiplexing (MIMO-OFDM) systems. Our approach consist of
applying the PSO based PTS on each antenna of the system in order to find the optimal phase factors,
which is a straightforward method to get the minimum PAPR in such a system. The simulation results
demonstrate that the PSO based PTS algorithm when applied to MIMO-OFDM systems with a wide range
of phase factors, tends to give a high performance. In addition, there is no need to increase the number of
particles of the PSO algorithm to enhance the performance of the system. As a result of this, the complexity
of finding the minimum PAPR is kept at a reasonable level.
PAPR Reduction in OFDM using Active and Non-Active ChannelsIOSR Journals
Abstract : According to the request of advance communication field there should be high data rate in addition to both power efficiency and lower bit error rate. This request of high data rate can be achieved by the multi carrier modulation scheme using the OFDM technique. But the great drawback of the OFDM technique is its high peak to average power ratio (PAPR). High PAPR reduces OFDM signals by driving the analog amplifier to work in the nonlinear region, changing this way the signal and making the amplifier to consume more power. To reduce the PAPR methods exist which adjust or present new signals to battle large signal peaks. The methods which use data carrying channels are called active channel methods and which use redundant channel are called non active channel methods. This work deals with reduction of the PAPR of OFDM signal using both Active and Non Active Channels. Clipping technique has been applied to active channels and Tone reservation has been applied to Non Active Channels. By using both channels we can get considerable reduction in PAPR. Keywords:Orthogonal Frequency Division Multiplexing (OFDM), Peak to Average Power Ratio (PAPR), Power Amplifier (PA).
Hybrid approach to solve the problem of papr in ofdm signal a surveyeSAT Journals
“Orthogonal frequency division multiplexing
method used to achieve the today’s need of wireless communication
3GPP Association for the use of LTE. The
higher data rate, higher bit rate, mitigated delay spread, lower multipath distortion,
OFDM system has few major issues associated with
ratio (PAPR)” associated with the signal.
interleaved OFDM, selective mapping (SLM)
windowing, clipping, filtering, tone rejection(TR), tone injection(TI), compandin
Analyses and performance of techniques papr reduction for stbc mimo ofdm syst...ijwmn
An OFDM system is combined with multiple-input mult
iple-output (MIMO) in order to increase the
diversity gain and system capacity over the time va
riant frequency-selective channels. However, a maj
or
drawback of MIMO-OFDM system is that the transmitte
d signals on different antennas might exhibit high
peak-to-average power ratio (PAPR).In this paper, w
e present a PAPR analysis reduction of space-time-
block-coded (STBC) MIMO-OFDM system for 4G wireless
networks. Several techniques have been used to
reduce the PAPR of the (STBC) MIMOOFDM system: clip
ping and filtering, partial transmit sequence
(PTS) and selected mapping (SLM). Simulation result
s show that clipping and filtering provides a bette
r
PAPR reduction than the others methods and only SLM
technique conserve the PAPR reduction in
reception part of signal.
Performance improvement for papr reduction in lte downlink system with ellipt...IJCNCJournal
This paper is concerned with the performance improvement of PAPR reduction of orthogonal frequency division multiplexing (OFDM) signal using amplitude clipping & filtering based design. Note that OFDM is one of the well adept multi-carrier multiplexing transmission scheme which has been implemented in long term evolution (LTE) downlink. Nonetheless peak to average power ratio (PAPR) is the more rattling problem with OFDM, consequently in this paper a reduction procedure of the PAPR by using amplitude clipping and filtering is proposed. Here we used IIR bandpass elliptic filter after amplitude clipping to
reduce the PAPR. The performance of the system in terms of bit error rate (BER) is also canvased as a new
filter based clipping method. Our results show that the proposed methodology of clipping method with the
IIR elliptic band pass filter significantly reduces the PAPR value.
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.
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.
Spectrally efficient multicarrier modulation system for visible light communi...IJECEIAES
Visible Light Communication (VLC) has become an accolade to its radio frequency counterpart. In VLC system, orthogonal frequency division multiplexing (OFDM) has drawn much attention, because of simple equalization, high spectral efficiency, high data rate and robustness to intersymbol interference (ISI). Besides, there are emerging applications that ought to be gotten with low latency and high reliability. To diminish power requirements with no transmission capacity extension, Trellis coded modulation (TCM) is utilized as a part of the framework in which the free distance of trellis diagram is equivalent to the minimum distance between the points of constellation focuses in partitioned subsets, which augments the coding gain up i.e. the performance parameter viably. TCM together with VLC-OFDM enhances the transmission execution in reasonable frameworks. In this paper, we propose OFDM which is based on TCM and is planned and exeuted for digitized OFDM frameworks by presenting delta sigma modulation (DSM) considering VLC channel. Simulation results show that the proposed TCM based VLC-OFDM offers incredible robustness against noises and nonlinear degradation.
Performance analysis of papr reduction techniques in multicarrier modulation ...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 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.
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
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.
Comparison of Various Waveform Contenders of 5G Wireless Communication Based ...ijtsrd
This paper presents an extensive and fair comparison among the most promising waveform contenders for the 5G air interface which includes- Filtered OFDM, Filter-bank multi carrier (FBMC), universal filtered multi-carrier (UFMC) has been compared with OFDM in terms of spectral efficiency and bit error rate using mat lab. The disadvantages of OFDM have been addressed and it has shown that (fofdm), (UFMC), (FBMC) could be a more effective solution. FBMC is a method for improving out of band (OOB) characteristics by filtering each subcarrier, it is also expected to improve the Inter-Carrier Interference (ICI) characteristics while UFMC is a method for improving OOB characteristics by filtering each block. Raksha Vishnoi | Saurabh Gaur | Ashish Verma"Comparison of Various Waveform Contenders of 5G Wireless Communication Based on OFDM" Published in International Journal of Trend in Scientific Research and Development (ijtsrd), ISSN: 2456-6470, Volume-2 | Issue-4 , June 2018, URL: http://www.ijtsrd.com/papers/ijtsrd15637.pdf http://www.ijtsrd.com/engineering/electronics-and-communication-engineering/15637/comparison-of-various-waveform-contenders-of-5g-wireless-communication-based-on-ofdm/raksha-vishnoi
Comparative Analysis of PAPR Reduction Techniques in OFDM Using Precoding Tec...IJSRD
In this modern era, Orthogonal Frequency Division Multiplexing (OFDM) has been proved to be an explicit promising technique for wired and wireless systems because of its several advantages like high spectral efficiency, robustness against frequency selective fading, relatively simple receiver implementation etc. Besides having a number of advantages OFDM suffers from few disadvantages like high Peak to Average Power Ratio (PAPR), Intercarrier Interference (ICI), Intersymbol Interference (ISI) etc. These detrimental effects, if not compensated properly and timely, can result in system performance degradation. This paper mainly concentrates on reduction of PAPR.A comparisons have been made between various precoding techniques against conventional OFDM.
Peak detection using wavelet transformIJCNCJournal
A new work based-wavelet transform is designed to overcome one of the main drawbacks that found in the
present new technologies. Orthogonal Frequency Division Multiplexing (OFDM)is proposed in the
literature to enhance the multimedia resolution. However, the high peak power (PAPR) values will obstruct
such achievements. Therefore, a new proposition is found in this work, making use of the wavelet
transforms methods, and it is divided into three main stages; de-noising stage, thresholding stage and then
the replacement stage.
In order to check the system stages validity; a mathematical model has been built and its checked after
using a MATLAB simulation. A simulated bit error rate (BER) achievement will be compared with our
previously published work, where an enhancement from 8×10-1 to be 5×10-1 is achieved. Moreover, these
results will be compared to the work found in the literature, where we have accomplished around 27%
PAPR extra reduction.
As a result, the BER performance has been improved for the same bandwidth occupancy. Moreover and
due to the de-noise stage, the verification rate has been improved to reach 81%. This is in addition to the
noise immunity enhancement.
Performance analysis on the basis of a comparative study between multipath ra...ijmnct
Interference is the most important issue for present wireless communication. There are various kinds of
channel used in wireless communication. Here I want to show a performance analysis on the basis of two
different channels – AWGN and Multipath Rayleigh fading channel. This is the comparative analysis with
different kinds of modulation techniques. Here I have also measured the Bit Error Rate with respect to
different modulation techniques and compare the rate in different channels. My objective is to compare the
different characteristics of the transmitter and receiver for different types of channels and modulators.
Comparative evaluation of bit error rate for different ofdm subcarriers in ra...ijmnct
In the present situation, the expectation about the quality of signals in wireless communication is as high as possible. This quality issue is dependent upon the different communication parameters. One of the most important issues is to reduce the bit error rate (BER) to enhance the performance of the system. This paper provides a comparative analysis on the basis of this bit error rate. I have compared the BER for different number of subcarriers in OFDM system for BPSK modulation scheme. I have taken 6 varieties of data subcarriers to analyze this comparison. Here my target is to reach at the lowest level of BER for BPSK modulation. That is achieved at 2048 number of subcarriers.
A mobile ad-hoc network (MANET) is a self structured infrastructure less network of mobile devices
connected by wireless. Each device in a MANET is free to move independently in any direction, and will
therefore change its links to other devices frequently. Load balancing is a technique to share out workload
across network links, to achieve maximize throughput, minimize response time, and avoid overload. Load
imbalance is a one of the critical issue in the ad-hoc network. Particle Swarm Optimization (PSO) method
is used to implement our proposed technique. In this Paper two algorithms are used for balancing the
nodes in the network. Identify the unfair nodes location next allocate and balance the load between the
nodes in the network. The simulation results show that this approach is more effective in terms of packet
delivery ratio, average end-to-end delay, load distribution, packet delay variation, packet reordering, and
throughput.
Ergodic capacity analysis for underlay cognitive radio systemijmnct
Cognitive radio technology has been proposed as a viable solution to the spectrum scarcity problem faced
by world today. The technology allows opportunistic spectrum access to the licensed frequency band by
unlicensed user without causing any harmful interference to the licensed primary user. In this paper,
ergodic channel capacity is investigated for underlay spectrum sharing system under maximum and
received power constraint at licensed primary receiver. The time varying discrete time fading channels are
assumed to undergo Rayleigh flat fading environment. Numerical simulations have been done to support
theoretical results
Performance Evaluation of PAPR Reduction with SER and BER by Modified Clippin...ijcsse
This paper work focuses on performance analysis of PAPR reduction of orthogonal frequency division multiplexing (OFDM) using amplitude clipping & filtering based design. Now a days one of the most proficient multi-carrier transmission techniques widely used today is orthogonal frequency division multiplexing (OFDM) which has been implemented by the next generation wireless communication technology: Long Term Evolution (LTE). Extra robustness to multipath fading and impulse noise is provided OFDM. It eliminates inter symbol interference (ISI) & inter carrier interference (ICI) with certain procedure. Therefore peak to average power ratio (PAPR) is the basic problem with OFDM. However in this paper we proposed a reduction procedure of the PAPR by using clipping and filtering. Here we use a composed high pass , low pass & Chevyshev band pass filter II after amplitude clipping to reduce the PAPR. The performance of the system in terms of bit error rate (BER) and symbol error rate (SER) is also investigated as a new filter based clipping method is proposed. Our proposed clipping method with and composed high pass the Chevyshev bandpass filter II in PAPR performance of the system with a little compromise of BER & SER showing the significant improvement in Quadrature Amplitude Modulation (QAM).
Reducing the Peak to Average Power Ratio of Mimo-Ofdm SystemsIJCNCJournal
In this paper, we proposed a particle swarm optimization (PSO) based partial transmit sequence (PTS)
technique in order to achieve the lowest Peak-to-Average Power Ratio(PAPR) in Multiple Input Multiple
Output- Orthogonal Frequency Division Multiplexing (MIMO-OFDM) systems. Our approach consist of
applying the PSO based PTS on each antenna of the system in order to find the optimal phase factors,
which is a straightforward method to get the minimum PAPR in such a system. The simulation results
demonstrate that the PSO based PTS algorithm when applied to MIMO-OFDM systems with a wide range
of phase factors, tends to give a high performance. In addition, there is no need to increase the number of
particles of the PSO algorithm to enhance the performance of the system. As a result of this, the complexity
of finding the minimum PAPR is kept at a reasonable level.
PAPR Reduction in OFDM using Active and Non-Active ChannelsIOSR Journals
Abstract : According to the request of advance communication field there should be high data rate in addition to both power efficiency and lower bit error rate. This request of high data rate can be achieved by the multi carrier modulation scheme using the OFDM technique. But the great drawback of the OFDM technique is its high peak to average power ratio (PAPR). High PAPR reduces OFDM signals by driving the analog amplifier to work in the nonlinear region, changing this way the signal and making the amplifier to consume more power. To reduce the PAPR methods exist which adjust or present new signals to battle large signal peaks. The methods which use data carrying channels are called active channel methods and which use redundant channel are called non active channel methods. This work deals with reduction of the PAPR of OFDM signal using both Active and Non Active Channels. Clipping technique has been applied to active channels and Tone reservation has been applied to Non Active Channels. By using both channels we can get considerable reduction in PAPR. Keywords:Orthogonal Frequency Division Multiplexing (OFDM), Peak to Average Power Ratio (PAPR), Power Amplifier (PA).
Hybrid approach to solve the problem of papr in ofdm signal a surveyeSAT Journals
“Orthogonal frequency division multiplexing
method used to achieve the today’s need of wireless communication
3GPP Association for the use of LTE. The
higher data rate, higher bit rate, mitigated delay spread, lower multipath distortion,
OFDM system has few major issues associated with
ratio (PAPR)” associated with the signal.
interleaved OFDM, selective mapping (SLM)
windowing, clipping, filtering, tone rejection(TR), tone injection(TI), compandin
Analyses and performance of techniques papr reduction for stbc mimo ofdm syst...ijwmn
An OFDM system is combined with multiple-input mult
iple-output (MIMO) in order to increase the
diversity gain and system capacity over the time va
riant frequency-selective channels. However, a maj
or
drawback of MIMO-OFDM system is that the transmitte
d signals on different antennas might exhibit high
peak-to-average power ratio (PAPR).In this paper, w
e present a PAPR analysis reduction of space-time-
block-coded (STBC) MIMO-OFDM system for 4G wireless
networks. Several techniques have been used to
reduce the PAPR of the (STBC) MIMOOFDM system: clip
ping and filtering, partial transmit sequence
(PTS) and selected mapping (SLM). Simulation result
s show that clipping and filtering provides a bette
r
PAPR reduction than the others methods and only SLM
technique conserve the PAPR reduction in
reception part of signal.
Performance improvement for papr reduction in lte downlink system with ellipt...IJCNCJournal
This paper is concerned with the performance improvement of PAPR reduction of orthogonal frequency division multiplexing (OFDM) signal using amplitude clipping & filtering based design. Note that OFDM is one of the well adept multi-carrier multiplexing transmission scheme which has been implemented in long term evolution (LTE) downlink. Nonetheless peak to average power ratio (PAPR) is the more rattling problem with OFDM, consequently in this paper a reduction procedure of the PAPR by using amplitude clipping and filtering is proposed. Here we used IIR bandpass elliptic filter after amplitude clipping to
reduce the PAPR. The performance of the system in terms of bit error rate (BER) is also canvased as a new
filter based clipping method. Our results show that the proposed methodology of clipping method with the
IIR elliptic band pass filter significantly reduces the PAPR value.
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.
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.
Spectrally efficient multicarrier modulation system for visible light communi...IJECEIAES
Visible Light Communication (VLC) has become an accolade to its radio frequency counterpart. In VLC system, orthogonal frequency division multiplexing (OFDM) has drawn much attention, because of simple equalization, high spectral efficiency, high data rate and robustness to intersymbol interference (ISI). Besides, there are emerging applications that ought to be gotten with low latency and high reliability. To diminish power requirements with no transmission capacity extension, Trellis coded modulation (TCM) is utilized as a part of the framework in which the free distance of trellis diagram is equivalent to the minimum distance between the points of constellation focuses in partitioned subsets, which augments the coding gain up i.e. the performance parameter viably. TCM together with VLC-OFDM enhances the transmission execution in reasonable frameworks. In this paper, we propose OFDM which is based on TCM and is planned and exeuted for digitized OFDM frameworks by presenting delta sigma modulation (DSM) considering VLC channel. Simulation results show that the proposed TCM based VLC-OFDM offers incredible robustness against noises and nonlinear degradation.
Performance analysis of papr reduction techniques in multicarrier modulation ...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 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.
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
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.
Comparison of Various Waveform Contenders of 5G Wireless Communication Based ...ijtsrd
This paper presents an extensive and fair comparison among the most promising waveform contenders for the 5G air interface which includes- Filtered OFDM, Filter-bank multi carrier (FBMC), universal filtered multi-carrier (UFMC) has been compared with OFDM in terms of spectral efficiency and bit error rate using mat lab. The disadvantages of OFDM have been addressed and it has shown that (fofdm), (UFMC), (FBMC) could be a more effective solution. FBMC is a method for improving out of band (OOB) characteristics by filtering each subcarrier, it is also expected to improve the Inter-Carrier Interference (ICI) characteristics while UFMC is a method for improving OOB characteristics by filtering each block. Raksha Vishnoi | Saurabh Gaur | Ashish Verma"Comparison of Various Waveform Contenders of 5G Wireless Communication Based on OFDM" Published in International Journal of Trend in Scientific Research and Development (ijtsrd), ISSN: 2456-6470, Volume-2 | Issue-4 , June 2018, URL: http://www.ijtsrd.com/papers/ijtsrd15637.pdf http://www.ijtsrd.com/engineering/electronics-and-communication-engineering/15637/comparison-of-various-waveform-contenders-of-5g-wireless-communication-based-on-ofdm/raksha-vishnoi
Comparative Analysis of PAPR Reduction Techniques in OFDM Using Precoding Tec...IJSRD
In this modern era, Orthogonal Frequency Division Multiplexing (OFDM) has been proved to be an explicit promising technique for wired and wireless systems because of its several advantages like high spectral efficiency, robustness against frequency selective fading, relatively simple receiver implementation etc. Besides having a number of advantages OFDM suffers from few disadvantages like high Peak to Average Power Ratio (PAPR), Intercarrier Interference (ICI), Intersymbol Interference (ISI) etc. These detrimental effects, if not compensated properly and timely, can result in system performance degradation. This paper mainly concentrates on reduction of PAPR.A comparisons have been made between various precoding techniques against conventional OFDM.
Peak detection using wavelet transformIJCNCJournal
A new work based-wavelet transform is designed to overcome one of the main drawbacks that found in the
present new technologies. Orthogonal Frequency Division Multiplexing (OFDM)is proposed in the
literature to enhance the multimedia resolution. However, the high peak power (PAPR) values will obstruct
such achievements. Therefore, a new proposition is found in this work, making use of the wavelet
transforms methods, and it is divided into three main stages; de-noising stage, thresholding stage and then
the replacement stage.
In order to check the system stages validity; a mathematical model has been built and its checked after
using a MATLAB simulation. A simulated bit error rate (BER) achievement will be compared with our
previously published work, where an enhancement from 8×10-1 to be 5×10-1 is achieved. Moreover, these
results will be compared to the work found in the literature, where we have accomplished around 27%
PAPR extra reduction.
As a result, the BER performance has been improved for the same bandwidth occupancy. Moreover and
due to the de-noise stage, the verification rate has been improved to reach 81%. This is in addition to the
noise immunity enhancement.
Performance analysis on the basis of a comparative study between multipath ra...ijmnct
Interference is the most important issue for present wireless communication. There are various kinds of
channel used in wireless communication. Here I want to show a performance analysis on the basis of two
different channels – AWGN and Multipath Rayleigh fading channel. This is the comparative analysis with
different kinds of modulation techniques. Here I have also measured the Bit Error Rate with respect to
different modulation techniques and compare the rate in different channels. My objective is to compare the
different characteristics of the transmitter and receiver for different types of channels and modulators.
Comparative evaluation of bit error rate for different ofdm subcarriers in ra...ijmnct
In the present situation, the expectation about the quality of signals in wireless communication is as high as possible. This quality issue is dependent upon the different communication parameters. One of the most important issues is to reduce the bit error rate (BER) to enhance the performance of the system. This paper provides a comparative analysis on the basis of this bit error rate. I have compared the BER for different number of subcarriers in OFDM system for BPSK modulation scheme. I have taken 6 varieties of data subcarriers to analyze this comparison. Here my target is to reach at the lowest level of BER for BPSK modulation. That is achieved at 2048 number of subcarriers.
A mobile ad-hoc network (MANET) is a self structured infrastructure less network of mobile devices
connected by wireless. Each device in a MANET is free to move independently in any direction, and will
therefore change its links to other devices frequently. Load balancing is a technique to share out workload
across network links, to achieve maximize throughput, minimize response time, and avoid overload. Load
imbalance is a one of the critical issue in the ad-hoc network. Particle Swarm Optimization (PSO) method
is used to implement our proposed technique. In this Paper two algorithms are used for balancing the
nodes in the network. Identify the unfair nodes location next allocate and balance the load between the
nodes in the network. The simulation results show that this approach is more effective in terms of packet
delivery ratio, average end-to-end delay, load distribution, packet delay variation, packet reordering, and
throughput.
Ergodic capacity analysis for underlay cognitive radio systemijmnct
Cognitive radio technology has been proposed as a viable solution to the spectrum scarcity problem faced
by world today. The technology allows opportunistic spectrum access to the licensed frequency band by
unlicensed user without causing any harmful interference to the licensed primary user. In this paper,
ergodic channel capacity is investigated for underlay spectrum sharing system under maximum and
received power constraint at licensed primary receiver. The time varying discrete time fading channels are
assumed to undergo Rayleigh flat fading environment. Numerical simulations have been done to support
theoretical results
An alarming signal in mobile telecommunication industry a study in malaysiaijmnct
The use of products and services of the mobile telecommunication industry becomes a part and parcel of
each human being around the globe irrespective of the age. It is hardly visible to see people without the use
of telecommunication technology in today’s world. The present research article examines the alarming
signal of market saturation of telecommunication companies in Malaysia as internal competitors is
increasing in number and age restriction of 18 years and above for legally registered owners of mobiles.
The saturation in the mobile telecommunication market is due to the relative low birth rate in Malaysia, the
eligible population to register a mobile phone is not proportional to telecommunication service providers.
In addition, there is also new Mobile Virtual Network Operators (MVNO) which magnifies the problem
further. Otherwise the local service providers have efficient and effective networking with other countries;
the sustainability of the telecommunication company's performance is at stake.
Network simulators for next generation networks an overviewijmnct
In this modern era of technology, the advancement and development specifically associated with network
simulators make them a significant tool for enhancing fundamental understanding in the field of next
generation wireless network technologies, worldwide. Network simulators provide consent to investigators
and developers to test diverse scenarios with an ease that are very tricky, intricate or expensive to simulate
in real world. These are proven to be incredibly effective and efficient in developing basic knowledge by
analysing distinct layers of the hypothetical as well as real-life objects. It is of the most important to test a
newly proposed protocol in a real-world before actual placement. Nowadays, most of the research
organizations, universities and viable industries are applying a great sum of effort in the development of
new sophisticated network simulators used for next generation wireless networks. In this paper, some of the
advanced “widely used” wireless network simulators (commercial and non-commercial such as NS-2; NS-
3; OPNET; NetSim; OMNeT++; REAL; J-Sim and QualNet etc.) available in recent years are presented
with their characteristics such as types, interface, availability, network impairments and support for
network protocol. Most importantly, the documented comparative overview helps the researchers and
academicians to choose optimal network simulator as per their interest and requirement.
Chaotic ANT System Optimization for Path Planning of the Mobile Robotscseij
This paper presents an improved ant system algorithm for path planning of the mobile robot under the complicated environment. To solve the drawback of the traditional ant colony system algorithm (ACS), which usually falls into the local optimum, we propose an improved ant colony system algorithm (IACS) based on chaos. Simulation experiments show that chaotic ant colony algorithm not only enhances the global search capability, but also has more effective than the traditional algorithm.
Critical Review Kepariwisataan Nasional 2012 ( Pendekatan Keilmuan )
Prof. Dr. Ir. Chafid Fandeli, MS ( Ketua Badan Penasehat Puspar UGM )
Thursday, November 22, 2012
Main Meeting Room
UGM Center for Tourism Studies
Note :
Some important things that could be discussed
1.Product better determine the success of a tourism destination
2.Economy factor will drive change values
3.A standardization not to eliminate the Authenticity Locality Uniqueness and Beauty
Para os empregadores de maior porte, como as empresas e equiparados a empresa pela Lei nº 8.212, de 1991, está em fase adiantada de desenvolvimento um módulo completo do eSocial. Nesse módulo, as empresas deverão transmitir suas informações através de arquivos gerados em seus sistemas de informática, utilizando leiautes padronizados. Haverá integração direta entre o sistema informatizado do empregador e o ambiente nacional do eSocial para transmissão dos arquivos, sem necessidade de preenchimento de telas web ou de programas geradores de escrituração ou declaração. Para utilização dessa opção, as empresas deverão possuir serviços web de conexão (webservice).
Os leiautes de arquivos estão sendo disponibilizados em versão inicial, ainda pendente de aprovação, e sua divulgação tem caráter informativo aos setores da sociedade interessados, dada a grande expectativa em torno do assunto. A versão final será disponibilizada em breve, por meio de portaria interministerial, editada pelo MF, MPS e MTE.
Fonte: https://www.esocial.gov.br/Leiautes.aspx
7 Fórmulas Definitivas para Mejorar tu BlogAntonRoMX
Atraer lectores está muy bien, pero seguro que también querréis convertirlos en compradores evadiendo las razones por las que tu blog podría no tener éxito, y para ello necesitaréis aseguraros en impulsar estas estrategias.
A Modified Design Of Acf Operation For Reducing Papr Of Ofdm Signaljosephjonse
Next generation wireless communication technology long term evolution (LTE) has implemented orthogonal frequency division multiplexing (OFDM) technique as a strong candidate for radio access systems. It has several attributes such as providing robustness to multipath fading & impulse noise, eliminating intersymbol interference (ISI), inter carrier interference (ICI) & the need for equalizers. The major challenging issue of OFDM technique is the high peak to average power ratio (PAPR) which is defined as the ratio of the peak power to the average power of the OFDM signal. A trade-off is necessary for reducing PAPR with increasing bit error rate (BER), computational complexity or data rate loss etc. In this paper, a moderately modified design of amplitude clipping & filtering operation (ACF) is proposed and implemented which shows the significant improvement in case of PAPR reduction for both quadrature phase shift keying (QPSK) & quadrature amplitude modulation (QAM) while increasing slight BER match up to to an existing method.
PAPR REDUCTION AND BIT ERROR RATE EVALUATION IN OFDM SYSTEM USING HYBRID TECH...pijans
Orthogonal frequency division multiplexing (OFDM) has become an important component of waveform
generation in wideband transmission. it's a superior technology for the high-speed rate of wired and
wireless communication systems. Currently, multiple-input multiple-output orthogonal frequency division
multiplexing (MIMO OFDM) systems are crucial wireless communication systems like 4G and 5G
networks & tactical communication. The OFDM has many advantages over other techniques like its high
capacity and immunity against multipath fading channels. However, one amongst the foremost drawbacks
of the OFDM system is that the high-peak-to-average power ratio (PAPR) that leads the system to provide
in-band distortion and out-of-band radiation and reduces its efficiency. This problem increases with a rise
within the number of transmit antennas. Therefore, it's highly desirable to cut back the PAPR of an OFDM
signal. For this, numerous techniques are proposed to beat the PAPR problem like i) Selective mapping
(SLM) ii) Partial transmit sequence (PTS), iii) Clipping, iv) Clipping and filtering. All of those are reduced
the PAPR by generating alternative subcarrier vector that are statistically independent OFDM symbols for
a given data frame and transmitting the symbol with rock bottom peak power. During this paper we also
proposed, some hybrid techniques. The hybrid techniques are the technique of clipping is employed in
conjunction with SLM and PTS to cut back computational complexity. And also the combination of SLM-
PTS to scale back PAPR. Simulations are acquainted with analyze the efficiency of the techniques used
which signifies OFDM to be providing much better PAPR reduction and a way better Bit Error Rate
(BER). it's shown in simulation results that the proposed scheme performs well reducing PAPR. But the
proposed scheme is more complex than the prevailing techniques.
PAPR REDUCTION AND BIT ERROR RATE EVALUATION IN OFDM SYSTEM USING HYBRID TECH...pijans
Orthogonal frequency division multiplexing (OFDM) has become an important component of waveform
generation in wideband transmission. it's a superior technology for the high-speed rate of wired and
wireless communication systems. Currently, multiple-input multiple-output orthogonal frequency division
multiplexing (MIMO OFDM) systems are crucial wireless communication systems like 4G and 5G
networks & tactical communication. The OFDM has many advantages over other techniques like its high
capacity and immunity against multipath fading channels. However, one amongst the foremost drawbacks
of the OFDM system is that the high-peak-to-average power ratio (PAPR) that leads the system to provide
in-band distortion and out-of-band radiation and reduces its efficiency. This problem increases with a rise
within the number of transmit antennas. Therefore, it's highly desirable to cut back the PAPR of an OFDM
signal. For this, numerous techniques are proposed to beat the PAPR problem like i) Selective mapping
(SLM) ii) Partial transmit sequence (PTS), iii) Clipping, iv) Clipping and filtering. All of those are reduced
the PAPR by generating alternative subcarrier vector that are statistically independent OFDM symbols for
a given data frame and transmitting the symbol with rock bottom peak power. During this paper we also
proposed, some hybrid techniques. The hybrid techniques are the technique of clipping is employed in
conjunction with SLM and PTS to cut back computational complexity. And also the combination of SLMPTS to scale back PAPR. Simulations are acquainted with analyze the efficiency of the techniques used
which signifies OFDM to be providing much better PAPR reduction and a way better Bit Error Rate
(BER). it's shown in simulation results that the proposed scheme performs well reducing PAPR. But the
proposed scheme is more complex than the prevailing techniques.
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
PAPR REDUCTION TECHNIQUES AND THEIR BIT ERROR RATE MEASUREMENT AT OFDM IN LTE...pijans
Orthogonal frequency division multiplexing (OFDM) has become an indispensable part of waveform generation in wideband digital communication since its first appearance in digital audio broadcasting (DAB)and it is indeed in use. These descriptions are simplified version of the detailed descriptions provided by 3gpp. It is a superior technology for the high-speed data rate of wire-line and wireless communication systems. The OFDM has many advantages over other techniques such as its high capacity and immunity against multipath fading channels. However ,one of the main drawbacks of the OFDM system is the high-peak-to-average power ratio (PAPR) that leads the system to produce in-band distortion and out-of-band radiation because of the non-linearity and reduces its efficiency is the distortion of the signal caused at the High Power Amplifier (HPA) of a transmitter . Therefore, it is highly desirable to reduce the PAPR of an OFDM signal. For this, numerous techniques have been proposed to overcome the PAPR problem such as i) selective mapping(SLM) ii) partial transmit sequence (PTS), iii) clipping, iv) clipping and filtering. In this paper, the PTS technique was analytically reviewed as one of the important methods to reduce the high PAPR problem. Simulations are used to analyze the efficiency of the techniques used which signifies OFDM to be providing much better PAPR reduction and a better Bit Error Rate (BER) . From simulation results clipping method shows good PAPR reduction with significant amount of BER degradation. Clipping and filtering method shows slight increase in PAPR with small degradation in BER performance than Clipping method and both methods are computationally less complex. PTS provides good PAPR reduction with high computational complexity.
PAPR REDUCTION TECHNIQUES AND THEIR BIT ERROR RATE MEASUREMENT AT OFDM IN LTE...pijans
Orthogonal frequency division multiplexing (OFDM) has become an indispensable part of waveform
generation in wideband digital communication since its first appearance in digital audio broadcasting
(DAB)and it is indeed in use. These descriptions are simplified version of the detailed descriptions
provided by 3gpp. It is a superior technology for the high-speed data rate of wire-line and wireless
communication systems. The OFDM has many advantages over other techniques such as its high capacity
and immunity against multipath fading channels. However ,one of the main drawbacks of the OFDM
system is the high-peak-to-average power ratio (PAPR) that leads the system to produce in-band distortion
and out-of-band radiation because of the non-linearity and reduces its efficiency is the distortion of the
signal caused at the High Power Amplifier (HPA) of a transmitter . Therefore, it is highly desirable to
reduce the PAPR of an OFDM signal. For this, numerous techniques have been proposed to overcome the
PAPR problem such as i) selective mapping(SLM) ii) partial transmit sequence (PTS), iii) clipping, iv)
clipping and filtering. In this paper, the PTS technique was analytically reviewed as one of the important
methods to reduce the high PAPR problem. Simulations are used to analyze the efficiency of the techniques
used which signifies OFDM to be providing much better PAPR reduction and a better Bit Error Rate
(BER) . From simulation results clipping method shows good PAPR reduction with significant amount of
BER degradation. Clipping and filtering method shows slight increase in PAPR with small degradation in
BER performance than Clipping method and both methods are computationally less complex. PTS provides
good PAPR reduction with high computational complexity.
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.
Comparative Analysis of PAPR Reduction Techniques in OFDM Using Precoding Tec...IJSRD
In this modern era, Orthogonal Frequency Division Multiplexing (OFDM) has been proved to be an explicit promising technique for wired and wireless systems because of its several advantages like high spectral efficiency, robustness against frequency selective fading, relatively simple receiver implementation etc. Besides having a number of advantages OFDM suffers from few disadvantages like high Peak to Average Power Ratio (PAPR), Intercarrier Interference (ICI), Intersymbol Interference (ISI) etc. These detrimental effects, if not compensated properly and timely, can result in system performance degradation. This paper mainly concentrates on reduction of PAPR.A comparisons have been made between various precoding techniques against conventional OFDM.
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.
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.
COMPARISON OF BER AND NUMBER OF ERRORS WITH DIFFERENT MODULATION TECHNIQUES I...Sukhvinder Singh Malik
This paper provides analysis of BER and Number of Errors for MIMO-OFDM wireless communication system by using different modulation techniques. Wireless designers constantly seek to improve the spectrum efficiency/capacity, coverage of wireless networks, and link reliability. So the performances of the wireless communication systems can be enhanced by using multiple transmit and receive antennas, which is generally referred to as the MIMO technique. Here analysis will be carried out for an OFDM wireless communication system using different modulation techniques and considering the effect and the wireless channel like AWGN, fading. Performance results will be evaluated numerically and graphically using the plots of BER versus SNR and plots of number of errors versus SNR.
Similar to Performance comparison of two clipping based filtering methods for papr reduction in ofdm signal (20)
UiPath Test Automation using UiPath Test Suite series, part 4DianaGray10
Welcome to UiPath Test Automation using UiPath Test Suite series part 4. In this session, we will cover Test Manager overview along with SAP heatmap.
The UiPath Test Manager overview with SAP heatmap webinar offers a concise yet comprehensive exploration of the role of a Test Manager within SAP environments, coupled with the utilization of heatmaps for effective testing strategies.
Participants will gain insights into the responsibilities, challenges, and best practices associated with test management in SAP projects. Additionally, the webinar delves into the significance of heatmaps as a visual aid for identifying testing priorities, areas of risk, and resource allocation within SAP landscapes. Through this session, attendees can expect to enhance their understanding of test management principles while learning practical approaches to optimize testing processes in SAP environments using heatmap visualization techniques
What will you get from this session?
1. Insights into SAP testing best practices
2. Heatmap utilization for testing
3. Optimization of testing processes
4. Demo
Topics covered:
Execution from the test manager
Orchestrator execution result
Defect reporting
SAP heatmap example with demo
Speaker:
Deepak Rai, Automation Practice Lead, Boundaryless Group and UiPath MVP
Kubernetes & AI - Beauty and the Beast !?! @KCD Istanbul 2024Tobias Schneck
As AI technology is pushing into IT I was wondering myself, as an “infrastructure container kubernetes guy”, how get this fancy AI technology get managed from an infrastructure operational view? Is it possible to apply our lovely cloud native principals as well? What benefit’s both technologies could bring to each other?
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FIDO Alliance Osaka Seminar: Passkeys at Amazon.pdf
Performance comparison of two clipping based filtering methods for papr reduction in ofdm signal
1. International journal of Mobile Network Communications & Telematics ( IJMNCT) Vol. 4, No.1, February 2014
DOI : 10.5121/ijmnct.2014.4103 23
PERFORMANCE COMPARISON OF TWO CLIPPING
BASED FILTERING METHODS FOR PAPR
REDUCTION IN OFDM SIGNAL
Md. Munjure Mowla1
, Md. Yeakub Ali2
and Rifat Ahmmed Aoni3
1,2
Department of Electronics & Telecommunication Engineering,
Rajshahi University of Engineering & Technology, Rajshahi - 6204, Bangladesh
3
Department of Electrical Engineering,
University of Malaya, Kuala Lumpur -50603, Malaysia
ABSTRACT
The growth of wireless communication technologies has been producing the intense demand for high-speed,
efficient, reliable voice & data communication. As a result, third generation partnership project (3GPP)
has implemented next generation wireless communication technology long term evolution (LTE) which is
designed to increase the capacity and speed of existing mobile telephone & data networks. LTE has
adopted a multicarrier transmission technique known as orthogonal frequency division multiplexing
(OFDM). OFDM meets the LTE requirement for spectrum flexibility and enables cost-efficient solutions for
very wide carriers. One major generic problem of OFDM technique is high peak to average power ratio
(PAPR) which is defined as the ratio of the peak power to the average power of the OFDM signal. A
trade-off is necessary for reducing PAPR with increasing bit error rate (BER), computational complexity or
data rate loss etc. In this paper, two clipping based filtering methods have been implemented & also
analyzed their modulation effects on reducing PAPR.
KEYWORDS
Bit Error rate (BER), Complementary Cumulative Distribution Function (CCDF), Long Term Evolution
(LTE), Orthogonal Frequency Division Multiplexing (OFDM) and Peak to Average Power Ratio (PAPR).
1. INTRODUCTION
Orthogonal frequency division multiplexing (OFDM) is a multicarrier modulation (MCM)
technique which seems to be an attractive candidate for fourth generation (4G) wireless
communication systems. The additional increasing demand on high data rates in wireless
communications systems has arisen in order to carry broadband services. OFDM offers high
spectral efficiency, immune to the multipath fading, low inter-symbol interference (ISI),
immunity to frequency selective fading and high power efficiency. OFDM has been adopted by
Digital Audio Broadcasting (DAB), Digital Video Broadcasting-Terrestrial (DVB-T) and
Wireless LAN (WLAN) systems. Additionally, OFDM has been used in the mobility mode of
IEEE802.16 WiMAX. Furthermore, it is currently a working specifications in 3GPP Long Term
Evolution (LTE) downlink, and is the candidate access method for the IEEE 802.22 Wireless
Regional Area Networks (WRAN) [1].
One of the major problems of OFDM is high peak to average power ratio (PAPR) of the transmit
signal. If the peak transmit power is limited by either regulatory or application constraints, the
effect is to reduce the average power allowed under multicarrier transmission relative to that
2. International journal of Mobile Network Communications & Telematics ( IJMNCT) Vol. 4, No.1, February 2014
24
under constant power modulation techniques. This lessens the range of multicarrier transmission.
Furthermore, the transmit power amplifier must be operated in its linear region (i.e., with a large
input back-off), where the power conversion is inefficient to avoid spectral growth of the
multicarrier signal in the form of intermodulation among subcarriers and out-of-band radiation.
This may have a deleterious effect on battery lifetime in mobile applications. As handy devices
have a finite battery life it is significant to find ways of reducing the PAPR allowing for a smaller
more efficient high power amplifier (HPA), which in turn will mean a longer lasting battery life.
In many low-cost applications, the problem of high PAPR may outweigh all the potential benefits
of multicarrier transmission systems [2].
A number of promising approaches or processes have been proposed & implemented to reduce
PAPR with the expense of increase transmit signal power, bit error rate (BER) & computational
complexity and loss of data rate, etc. So, a system trade-off is required. These techniques include
Amplitude Clipping and Filtering, Peak Windowing, Peak Cancellation, Peak Reduction Carrier,
Envelope Scaling, Decision-Aided Reconstruction (DAR), Coding, Partial Transmit Sequence
(PTS), Selective Mapping (SLM), Interleaving, Tone Reservation (TR), Tone Injection (TI),
Active Constellation Extension (ACE), Clustered OFDM, Pilot Symbol Assisted Modulation,
Nonlinear Companding Transforms etc [3].
2. THEORETICAL MODEL OF OFDM SYSTEM
OFDM is a special form of multicarrier modulation (MCM) with densely spaced subcarriers with
overlapping spectra, thus allowing multiple-access [4]. MCM works on the principle of
transmitting data by dividing the stream into several bit streams, each of which has a much lower
bit rate and by using these sub-streams to modulate several carriers.
Figure 1. Spectra of (a) An OFDM Sub-channel and (b) An OFDM Signal [1]
In multicarrier transmission, bandwidth divided in many non-overlapping subcarriers but not
necessary that all subcarriers are orthogonal to each other as shown in figure 1 (a) [4]. In OFDM
the sub-channels overlap each other to a certain extent as can be seen in figure 1 (b), which leads
to an efficient use of the total bandwidth. The information sequence is mapped into symbols,
which are distributed and sent over the N sub-channels, one symbol per channel. To permit dense
packing and still ensure that a minimum of interference between the sub-channels is encountered,
the carrier frequencies must be chosen carefully. By using orthogonal carriers, frequency domain
can be viewed so as the frequency space between two sub-carriers is given by the distance to the
first spectral null [1].
2.1. Mathematical Explanation of OFDM Signals
In OFDM systems, a defined number of successive input data samples are modulated first (e.g,
PSK or QAM), and then jointly correlated together using inverse fast Fourier transform (IFFT) at
the transmitter side. IFFT is used to produce orthogonal data subcarriers. Let, data block of length
3. International journal of Mobile Network Communications & Telematics ( IJMNCT) Vol. 4, No.1, February 2014
25
N is represented by a vector, X=[X0, X1……. XN-1]T
. Duration of any symbol XK in the set X is T
and represents one of the sub-carriers set. As the N sub-carriers chosen to transmit the signal are
orthogonal, so we can have, fn = n f, where n f = 1/NT and NT is the duration of the OFDM data
block X. The complex data block for the OFDM signal to be transmitted is given by [2],
∑
−
=
∆
=
1
0
21
)(
N
n
ftnj
neX
N
tx π
NTt ≤≤0 (1)
Where,
1−=j , f is the subcarrier spacing and NT denotes the useful data block period. In OFDM
the subcarriers are chosen to be orthogonal (i.e., f = 1/NT). However, OFDM output symbols
typically have large dynamic envelope range due to the superposition process performed at the
IFFT stage in the transmitter.
3. OVERVIEW OF PAPR
Presence of large number of independently modulated sub-carriers in an OFDM system the peak
value of the system can be very high as compared to the average of the whole system. Coherent
addition of N signals of same phase produces a peak which is N times the average signal [2].
PAPR is widely used to evaluate this variation of the output envelope. PAPR is an important
factor in the design of both high power amplifier (PA) and digital-to-analog (D/A) converter, for
generating error-free (minimum errors) transmitted OFDM symbols. So, the ratio of peak power
to average power is known as PAPR.
The PAPR of the transmitted signal is defined as [5],
2 2
0 0
2
0
max | ( ) | max | ( ) |
[ ( )]
1
| ( ) |
t NT t NT
NT
av
x t x t
PAPR x t
P
x t dt
NT
≤ ≤ ≤ ≤
= =
∫
(2)
Where, Pav is the average power of and it can be computed in the frequency domain because
Inverse Fast Fourier Transform (IFFT) is a (scaled) unitary transformation.
To better estimated the PAPR of continuous time OFDM signals, the OFDM signals samples are
obtained by L times oversampling. L times oversampled time domain samples are LN point IFFT
of the data block with (L-1)N zero-padding. Therefore, the oversampled IFFT output can be
expressed as [2],
∑
−
=
=
1
0
/21
][
N
k
LNnkj
k eX
N
nx π
10 −≤≤ NLn (3)
It is known that the PAPR of the continuous-time signal cannot be obtained precisely by the use
of Nyquist rate sampling, which corresponds to the case of L = 1. It is shown in that L = 4 can
provide sufficiently accurate PAPR results.
The PAPR computed from the L-times oversampled time domain signal samples is given by[2],
PowerAverage
PowerPeak
PAPR
_
_
=
4. International journal of Mobile Network Communications & Telematics ( IJMNCT) Vol. 4, No.1, February 2014
26
2
0 1
2
max | ( ) |
{ [ ]}
[| ( ) | ]
t NL x n
PAPR x n
E x n
≤ ≤ −
= (4)
Where, E{.} is the Expectation Operator.
4. AMPLITUDE CLIPPING AND FILTERING
Amplitude Clipping and Filtering is one of the easiest techniques which may be under taken for
PAPR reduction for an OFDM system. A threshold value of the amplitude is fixed in this case to
limit the peak envelope of the input signal [5].
Figure 2. Clipping Function
The clipping ratio (CR) is defined as,
σ
A
CR = (5)
Where, A is the amplitude and is the root mean squared value of the unclipped OFDM signal.
The clipping function is performed in digital time domain, before the D/A conversion and the
process is described by the following expression,
= )( kxj
kc
k
Ae
x
x φ
Ax
Ax
k
k
>
≤
||
||
10 −≤≤ Nk (6)
Where , is the clipped signal, is the transmitted signal, A is the amplitude and is the
phase of the transmitted signal
4.1. Limitations of Clipping and Filtering
Clipping causes in-band signal distortion, resulting in BER performance degradation.
Clipping also causes out-of-band radiation, which imposes out-of-band interference
signals to adjacent channels. Although the out-of-band signals caused by clipping can
be reduced by filtering, it may affect high-frequency components of in-band signal
(aliasing) when the clipping is performed with the Nyquist sampling rate in the
discrete-time domain[6].
However, if clipping is performed for the sufficiently-oversampled OFDM signals
(e.g., L ≥4) in the discrete-time domain before a low-pass filter (LPF) and the signal
passes through a band-pass filter (BPF), the BER performance will be less degraded [6].
Filtering the clipped signal can reduce out-of-band radiation at the cost of peak regrowth.
The signal after filtering operation may exceed the clipping level specified for the
clipping operation [2].
5. International journal of Mobile Network Communications & Telematics ( IJMNCT) Vol. 4, No.1, February 2014
27
]
Proposed Filter
5. PROPOSED CLIPPING AND FILTERING SCHEME
As the major spotlight of this research is to reduce PAPR, so, in this simulation, we have trade-off
between PAPR reduction with BER increment. Very little amount of BER increment is desirable.
Pointing out the third limitation in section 4.1, Our Previous Work [7] showed that if clipped
signal passes through a Composed filter (FIR based HPF) before passing a LPF to reduce out-of-
band radiation, then it causes less BER degradation with medium amount of PAPR reduction than
an existing method [6]. Considering this concept, we have designed another scheme for clipping
& filtering method where clipped signal passes through a Composed filter (IIR based BPF) before
passing a LPF, then it causes a little bit more BER degradation but more amount of PAPR
reduction than our previous work[7].
This proposed scheme is shown in the figure 4. It shows a block diagram of a PAPR reduction
scheme using clipping and filtering, where L is the oversampling factor and N is the number of
subcarriers. The input of the IFFT block is the interpolated signal introducing N(L −1) zeros
(also, known as zero padding) in the middle of the original signal is expressed as,
(7)
In this system, the L-times oversampled discrete-time signal is generated as,
NL
fkmjNL
k
ekX
NL
mx .
21.
0
.][
.
1
][
∆−
=
∑ ′=′
π
, m = 0,1,…NL – 1 (8)
and is then modulated with carrier frequency fc to yield a passband signal .
Figure 4. Block Diagram of Proposed Clipping & Filtering Scheme.
Let denote the clipped version of which is expressed as,
(9)
Or,
L.N
Point
IFFT
fc
Digital
up
Conver
sion
Clipping
BPF
(IIR)
LPFL.N
Point
FFT
L.N
Point
IFFT
6. International journal of Mobile Network Communications & Telematics ( IJMNCT) Vol. 4, No.1, February 2014
28
(10)
Where, A is the pre-specified clipping level. After clipping, the signals are passed through the
Composed filter (Proposed Filter). This composed filter itself consists on a set of FFT-IFFT
operations where filtering takes place in frequency domain after the FFT function. The FFT
function transforms the clipped signal to frequency domain yielding The
information components of are passed to a band pass filter (BPF) producing This
filtered signal is passed to the unchanged condition of 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 thus obtain .
6. DESIGN AND SIMULATION PARAMETERS
In this simulation, an IIR digital filter (Chebyshev Type I) is used in the composed filtering.
Chebyshev Type I filter is equiripple in the passband and monotonic in the stopband. Type I filter
rolls off faster than type II filters. Chebyshev filter has the property that it minimizes the error
between the idealized and the actual filter characteristic over the range of the filter. Because of
the passband equiripple behaviour inherent in Chebyshev Type I filter, it has a smoother response.
Table 1 shows the values of parameters used in the QPSK & QAM system for analyzing the
performance of clipping and filtering technique [6]. We have simulated the both methods
(Previous and New) with the same parameters at first and compare each step.
Table 1. Parameters Used for Simulation of Clipping and Filtering.
Parameters Value
Bandwidth ( BW) 1 MHz
Over sampling factor (L) 8
Sampling frequency, fs = BW*L 8 MHz
Carrier frequency, fc 2 MHz
FFT Size / No. of Subscribers (N) 128
CP / GI size 32
Modulation Format QPSK and QAM
Clipping Ratio (CR) 0.8, 1.0, 1.2, 1.4, 1.6
6.1. Simulation Results for PAPR Reduction
At first, we simulate the PAPR distribution for CR values =0.8, 1.0, 1.2, 1.4, 1.6 with QPSK
modulation and N=128. Then, we simulate with QAM modulation and N=128 and compare
different situations.
6.1.1 Simulation Results: (QPSK and N=128)
7. International journal of Mobile Network Communications & Telematics ( IJMNCT) Vol. 4, No.1, February 2014
29
In the previous method, PAPR distribution for different CR value is shown in figure 5 (a). At
CCDF =10-1
, the unclipped signal value is 13.51 dB and others values for different CR are
tabulated in the table 2.
(a) Previous Method (b) Proposed Method
Figure 5. PAPR Distribution for CR=0.8,1.0,1.2,1.4,1.6 [QPSK and N=128]
In the proposed method, simulation shows the reduction of PAPR is shown for different CR
values in figure 5(b). At CCDF =10-1
, the unclipped signal value is 13.52 dB and others values for
different CR are tabulated in the table 2. From table 2, it is clearly observed that the proposed
method reduces PAPR with respect to previous work analysis [7].
Table 2. Comparison of Previous with Proposed Method for PAPR value [QPSK and N=128]
6.1.2 Simulation Results: (QAM and N=128)
The simulation results are now shown for QAM modulation and no. of subscribers, N=128. In the
previous method, PAPR distribution for different CR value is shown in figure 6 (a). At CCDF
=10-1
, the unclipped signal value is 13.11 dB and others values for different CR are tabulated in
the table 3. In the proposed method, simulation shows the reduction of PAPR is shown for
different CR values in figure 6(b). At CCDF =10-1
, the unclipped signal value is 13.65 dB and
others values for different CR are tabulated in the table 3.
CR
value
PAPR value
(dB)
(Previous)
PAPR value
(dB)
(Proposed)
Improvement in PAPR value
(dB)
0.8 5.11 4.21 0.90
1.0 5.18 4.67 0.51
1.2 5.65 5.21 0.44
1.4 6.04 5.72 0.32
1.6 6.51 6.29 0.22
2 4 6 8 10 12 14 16
10
-2
10
-1
10
0
PAPR0[dB]
CCDF=Probability(PAPR>PAPR0)
PAPR distribution for CR=0.8,1.0,1.2,1.4,1.6 [ QPSK N=128 ( Proposed)]
Unclipped
Clipped
Clipped & Filtering
CR=0.8
CR=0.8
2 4 6 8 10 12 14 16
10
-2
10
-1
10
0
PAPR0[dB]
CCDF=Probability(PAPR>PAPR0)
PAPR Distribution for CR=0.8,1.0,1.2,1.4,1.6[QPSK / N=128 (Previous)]
Unclipped
Clipped
Clipped & Filtering
CR=0.8
CR=0.8
8. International journal of Mobile Network Communications & Telematics ( IJMNCT) Vol. 4, No.1, February 2014
30
(a) Previous Method (b) Proposed Method
Figure 6. PAPR Distribution for CR=0.8,1.0,1.2,1.4,1.6 [QAM and N=128]
The previous method and proposed method PAPR distribution values for different CR values are
tabulated and differences are shown in table 3. From table 3, it is clearly observed that the
proposed method reduces PAPR with respect to previous work analysis [7] for QAM and N=128
also. So, proposed method works on efficiently for both QPSK & QAM.
Table 3. Comparison of Previous with Proposed Method for PAPR value [QAM and N=128]
CR value PAPR value
(dB)
(Previous)
PAPR value
(dB)
(Proposed)
Improvement in PAPR value
(dB)
0.8 4.97 4.21 0.76
1.0 5.25 4.65 0.60
1.2 5.67 5.11 0.56
1.4 6.09 5.71 0.38
1.6 6.51 6.27 0.24
Now, if we compare the values for different CR values in case of QPSK & QAM to show the
effect of modulation on proposed filter design, it is observed that for the same number of
subscribers (N=128) & low CR=0.8, there is no differences between using QAM & QPSK. But,
2 4 6 8 10 12 14 16
10
-2
10
-1
10
0
PAPR0[dB]
CCDF=Probability(PAPR>PAPR0)
PAPR Distribution for CR=0.8,1.0,1.2,1.4,1.6[ QAM / N=128 (Proposed Method)]
Unclipped
Clipped
Clipped & Filtering
CR=0.8
CR=0.8
2 4 6 8 10 12 14 16
10
-2
10
-1
10
0
PAPR0[dB]
CCDF=Probability(PAPR>PAPR0)
PAPR Distribution for CR=0.8,1.0,1.2,1.4,1.6[ QAM / N=128 (Previous)]
Unclipped
Clipped
Clipped & Filtering
CR=0.8
CR=0.8
9. International journal of Mobile Network Communications & Telematics ( IJMNCT) Vol. 4, No.1, February 2014
31
with the increasing value of CR, QAM provides less PAPR than QPSK. So, for high CR, QAM is
more suitable than QPSK in case of proposed filter.
6.2. Simulation Results for BER Performance
The clipped & filtered signal is then passed through the AWGN channel and BER are measured
for both previous & proposed methods. We have also simulated the analytical BER curve that is
shown in the curve. Figure 7 and figure 8 show the BER performance for QPSK and QAM with
N=128. It is seen from these figures that the BER increases as the CR decreases.
6.2.1 Simulation Results: (QPSK and N=128)
Now, for QPSK & N=128 with all other same data mentioned in table 1, both previous and
proposed methods are executed and resulted graphs are shown in figure 7(a) & figure 7(b)
respectively. It is observed from these two figures that BER increases slightly in proposed method
with respect to previous method for all same values of CR.
(a) Previous Method (b) Proposed Method
Figure 7. BER Performance [QPSK and N=128]
The measured BER value at 6 dB point is tabulated in table 4.
Table 4. Comparison of BER value for Previous & Proposed Method [QPSK and N=128]
CR value BER value
(Previous)
BER Value
(Proposed)
Difference in BER value
0.8 0.0752 0.10631 -0.03111
1.0 0.0616 0.09012 -0.02852
1.2 0.0492 0.07846 -0.02926
1.4 0.0411 0.06358 -0.02248
1.6 0.0339 0.05748 -0.02358
0 1 2 3 4 5 6 7 8 9 10
10
-3
10
-2
10
-1
10
0
EbNo(dB)
BER
BER Performance [QPSK/N=128 (Proposed Method)]
Analytical
Clipped
Clipped & Filtering
CR=1.6
CR=1.6
0 1 2 3 4 5 6 7 8 9 10
10
-3
10
-2
10
-1
10
0
EbNo(dB)
BER
BER Performance [QPSK / N=128 (Previous)]
Analytical
Clipped
Clipped & Filtering
CR=1.6
CR=1.6
10. International journal of Mobile Network Communications & Telematics ( IJMNCT) Vol. 4, No.1, February 2014
32
BER performance is measured and compared in both the table 4 (QPSK) & table 5(QAM) which
shows different CR values for both previous & proposed method in case of same parameter value.
From table 4, it is observed that, for CR values (0.8,1.0,1.2,1.4 & 1.6) , the difference magnitude
between previous & proposed method are 0.03111,0.02852,0.02926,0.02248 & 0.02358
respectively in QPSK. These BER degradations are acceptable as these are very low values.
6.1.2 Simulation Results: (QAM and N=128)
Again, for QAM & N=128 with all other same data mentioned in table 1, both previous and
proposed methods are executed and resulted graphs are shown in figure 8(a) & figure 8(b)
respectively.
(a) Previous Method (b) Proposed Method
Figure 8. BER Performance [QAM and N=128]
The measured BER value at 6 dB point is tabulated in table 5.
Table 5. Comparison of BER value for Previous & Proposed Method [QAM and N=128]
CR value BER value
(Previous)
BER Value
(Proposed)
Difference in BER value
0.8 0.07602 0.07535 0.00067
1.0 0.06256 0.06098 0.00158
1.2 0.05091 0.05433 -0.00342
1.4 0.04028 0.04631 -0.00603
1.6 0.03642 0.04211 -0.00569
0 1 2 3 4 5 6 7 8 9 10
10
-4
10
-3
10
-2
10
-1
10
0
EbNo(dB)
BER
BER Performance [ QAM / N=128 ( Proposed Method)]
Analytical
Clipped
Clipped & Filtering
CR=1.6
CR=1.6
0 1 2 3 4 5 6 7 8 9 10
10
-4
10
-3
10
-2
10
-1
10
0
EbNo(dB)
BER
BER Performance [QAM / N=128 (Previous)]
Analytical
Clipped
Clipped & Filtering
CR=1.6
CR=1.6
11. International journal of Mobile Network Communications & Telematics ( IJMNCT) Vol. 4, No.1, February 2014
33
From table 5, it is observed that BER increases slightly in proposed method with respect to
previous method for high value of CR= 1.2,1.4,1.6 but in low value of CR=0.8 & 1.0, QAM
provides better result ( less BER degradation) in case of proposed method.
6. CONCLUSION
In this paper, performances are compared for two different types of amplitude clipping & filtering
based PAPR reduction techniques have been analyzed. We ran the simulation for our two
techniques, i.e: previous and proposed upon QPSK & QAM. In the new proposed method, it is
observed from that for the same number of subscribers (N=128) & low CR=0.8, there is no
differences between using QAM & QPSK. But, with the increasing value of CR, QAM provides
less PAPR than QPSK. So, for high CR, QAM is more suitable than QPSK in case of proposed
filter. In case of BER, with gradual increasing of CR values, the differences of BER values for
QPSK become decreasing. But, it is also noticed that BER increases slightly in proposed method
with respect to previous method for high value of CR= 1.2,1.4,1.6 but in low value of CR=0.8 &
1.0, QAM provides better result ( less BER degradation) in case of proposed method. In this
simulation, ideal channel characteristics have been assumed. In order to estimate the OFDM
system performance in real world, multipath Rayleigh fading would be a major consideration in
next time. The increase number of subscribers (N) & higher modulation parameters could be
another assumption.
REFERENCES
[1] R. Prasad, OFDM for Wireless Communications Systems. London, Boston: Artech House, Inc, 2004.
[2] S. H. Han and J. H. Lee, “An overview of peak-to-average power ratio reduction techniques for
multicarrier transmission”, IEEE Wireless Comm, vol. 12, no.2, pp.56-65, Apr. 2005.
[3] Md. Munjure Mowla, “ Peak to average power ratio analysis and simulation in LTE system”, M.Sc
dissertation, Department of Electrical & Electronic Engineering, Rajshahi University of Engineering
& Technology, Bangladesh, 2013.
[4] Muhammad Atif Gulzar , Rashid Nawaz and Devendra Thapa, “Implementation of
MIMO-OFDM System for WiMAX”, M.Sc Dissertation, Department of Electrical
Engineering, Linnaeus University, Sweden, 2011.
[5] Natalia Revuelto, “PAPR reduction in OFDM systems”, M.Sc Dissertation, Universitat
Politecnica de Catalunya, Spain, 2008.
[6] Y.S. Cho, J. Kim, W.Y.Yang and C.G. Kang, MIMO OFDM Wireless Communications with MATLAB,
Singapore: John Wiley & Sons (Asia) Pte Ltd, 2010.
[7] M.M.Mowla and S.M.M. Hasan, “Performance improvement of PAPR reduction for OFDM signal in
LTE system”, International Journal of Wireless & Mobile Networks (IJWMN), Volume 5, Number 4,
August 2013 (ISSN: 0975-3834).
Authors
Md. Munjure Mowla is now working as an Assistant Professor in Electronics & Telecommunication
Engineering department of Rajshahi University Engineering & Technology (RUET) since November 2010.
He has completed M.Sc Engineering degree in Electrical & Electronic Engineering (EEE) from RUET in
May 2013. He has four years telecom job experience in the companies like operators, vendors, ICX etc of
Bangladesh telecom market. Mr. Mowla has published several international journals as well as conference
papers and three books. He is a member of IEEE, ComSoc (IEEE), Institutions of Engineers, Bangladesh
(IEB) and Bangladesh Electronics Society (BES). His research interest includes advanced wireless
communication including LTE, LTE-Advanced, green communication, smart grid communication etc.
12. International journal of Mobile Network Communications & Telematics ( IJMNCT) Vol. 4, No.1, February 2014
34
Md. Yeakub Ali has completed B.Sc Engineering degree in Electronics & Telecommunication
Engineering (ETE) from Rajshahi University Engineering & Technology (RUET) in January 2014. Now,
he is working as an engineer in a telecommunication company. His research area includes Wireless &
Mobile Communication, Satellite Communication & Radar.
Rifat Ahmmed Aoni has completed B.Sc Engineering degree in Electronics & Telecommunication
Engineering (ETE) from Rajshahi University Engineering & Technology (RUET) in September 2012.
Now, he is doing M.Sc (EEE) in University of Malaya, Malaysia. His research area includes Photonics,
Optical Fiber etc.