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).
Performance comparison of two clipping based filtering methods for papr reduc...ijmnct
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 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.
Adaptive Resource Allocation in MIMO-OFDM Communication Systemijsrd.com
Multiple Input and Multiple Output (MIMO) and Orthogonal Frequency Division Multiplexing (OFDM) system have the potential to achieve very high capacity depending on the propagation environment. The objective of this paper is the adaptive resource allocation in MIMOOFDM system using the waterfilling algorithm. Water filling solution is implemented for allocating the power in order to increase the channel capacity. The total system capacity is maximised subject to the constraints on total power, signal to noise ratio, and proportional fairness. Channel is assumed as a flat fading channel and the comparison is made for different 2x2, 2x3, 3x2 and 4x4 MIMO-OFDM systems using waterfilling algorithm with allocated power. Also in order to prove that the MIMOOFDM with waterfilling algorithm provides the best performance a comparison with various SISO - OFDM is done.
Abstract: The growing demand on wireless communication service has created the necessity to support higher data rates for multimedia services. .As next generation wireless communication networks are expected to provide broadband multimedia services such as voice, web browsing, video conferencing etc. For high data rate achievement one must enhance the capacity of the wireless communication system. The capacity of a communication system can be enhanced by using OFDM system. OFDM is commonly used for communication system due to its high transmission rate and robustness against multipath fading So as to enhance the capacity of fading channels the OFDM system are combined to form hybrid system. Capacity is the measure of maximum information that can be transmitted reliably over a channel. This paper review on different channel capacity enhancement techniques used in OFDM system is SVD (Singular Value Decomposition), water Filling algorithm.
New Technique Combining the Tone Reservation Method with Clipping Technique t...IJECEIAES
Nonlinear distortions and impairments appear in multicarrier signal with high fluctu- ations when amplified by a Radio Frequency Power Amplifier (RF PA). This article is a contribution to improving the Tone Reservation (TR) method dedicated to reducing fluctuations in the Orthogonal Frequency Division Multiplexing (OFDM) modulation. This method exploits the null sub-carriers in communications standards in order to generate a correction signal used to reduce the Peak-to-Average Power Ratio (PAPR) with nevertheless limited performances due to the reduced number of these sub-carriers. For this purpose, our contribution is to combine the TR method with the Clipping (CL) method to improve the PAPR reduction without significantly impacting the quality of transmissions. We also show the gain provided by this strategy compared to the use of classical methods. Experiments using a simulated example on a complete WiMax 802:16e transmitter have been made in order to investigate the PAPR reduction performances on presence of the non-linear Power Amplifier model based on gain compression response and phase distortion.
Performance comparison of two clipping based filtering methods for papr reduc...ijmnct
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 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.
Adaptive Resource Allocation in MIMO-OFDM Communication Systemijsrd.com
Multiple Input and Multiple Output (MIMO) and Orthogonal Frequency Division Multiplexing (OFDM) system have the potential to achieve very high capacity depending on the propagation environment. The objective of this paper is the adaptive resource allocation in MIMOOFDM system using the waterfilling algorithm. Water filling solution is implemented for allocating the power in order to increase the channel capacity. The total system capacity is maximised subject to the constraints on total power, signal to noise ratio, and proportional fairness. Channel is assumed as a flat fading channel and the comparison is made for different 2x2, 2x3, 3x2 and 4x4 MIMO-OFDM systems using waterfilling algorithm with allocated power. Also in order to prove that the MIMOOFDM with waterfilling algorithm provides the best performance a comparison with various SISO - OFDM is done.
Abstract: The growing demand on wireless communication service has created the necessity to support higher data rates for multimedia services. .As next generation wireless communication networks are expected to provide broadband multimedia services such as voice, web browsing, video conferencing etc. For high data rate achievement one must enhance the capacity of the wireless communication system. The capacity of a communication system can be enhanced by using OFDM system. OFDM is commonly used for communication system due to its high transmission rate and robustness against multipath fading So as to enhance the capacity of fading channels the OFDM system are combined to form hybrid system. Capacity is the measure of maximum information that can be transmitted reliably over a channel. This paper review on different channel capacity enhancement techniques used in OFDM system is SVD (Singular Value Decomposition), water Filling algorithm.
New Technique Combining the Tone Reservation Method with Clipping Technique t...IJECEIAES
Nonlinear distortions and impairments appear in multicarrier signal with high fluctu- ations when amplified by a Radio Frequency Power Amplifier (RF PA). This article is a contribution to improving the Tone Reservation (TR) method dedicated to reducing fluctuations in the Orthogonal Frequency Division Multiplexing (OFDM) modulation. This method exploits the null sub-carriers in communications standards in order to generate a correction signal used to reduce the Peak-to-Average Power Ratio (PAPR) with nevertheless limited performances due to the reduced number of these sub-carriers. For this purpose, our contribution is to combine the TR method with the Clipping (CL) method to improve the PAPR reduction without significantly impacting the quality of transmissions. We also show the gain provided by this strategy compared to the use of classical methods. Experiments using a simulated example on a complete WiMax 802:16e transmitter have been made in order to investigate the PAPR reduction performances on presence of the non-linear Power Amplifier model based on gain compression response and phase distortion.
Index modulation is one of the promising techniques for future communications systems due to many improvement over the classical orthogonal frequency division multiplexing systems such as single RF chain, increased throughput for the same modulation order, achieved tradeoff between the efficiencies of the power and the spectral, and elimination of inter-channel interference. Many forms of index modulation researches exist where symbols are conveyed in antennas, subcarriers, time slots, and the space-time matrix. Spatial modulation is one member of index modulation family where symbols are conveyed in activating transmit/receive antennas. In this paper, a modification to a standard multiple input single output scheme by integrating spatial modulation using simplified mathematical procedure is achieved. In the transmitter side, data and activation symbols are distributed simultaneously using mathematical module and floor functions. At the receiver, a simplified maximum likelihood detector is used to obtain transmitted pair of symbols. To verify this, MATLAB simulink is used to simulate a downlink system where spatial modulation is applied to a base station. Results for different transmit antenna number and modulation order are obtained in the form of bit error rate versus signal to noise ratio.
Peak to Average Power Ratio Reduction in Mc Cdma System by Using Pulse Shapin...IOSR Journals
Abstract: One of the drawback of multicarrier code division multiple access (MC CDMA) is the high peak to
average power ratio (PAPR). In this paper A novel scheme based on pulse shaping described for PAPR
reduction. Here three different pulse shaping filters (Raised cosine, Sinc power pulse and Nyqist pulse) are
described for PAPR reduction in MC CDMA system. The method is based on the proper selection of the pulses
for shaping the different sub carriers of the MC CDMA modulation scheme. It is shown by computer simulation
that the scheme achieves the significant improvement in PAPR reduction in MC CDMA system. Its
implementation complexity is much low in comparison to the previous published methods. Thus pulse shaping
technique can be used not only to shape the spectrum of the transmitted signal but also to reduce its PAPR. In
computer simulation It is observed that by using nyquist pulse near about 6.8 db PAPR is obtained. Which is
considerable PAPR reduction than a PAPR value of Original MC CDMA signal
Keywords: MC CDMA, PAPR, PULSE SHAPING, BPSK
An Approach to Improve the Quality of Service in OFDMA Relay Networks via Re-...iosrjce
With the next-generation cellular networks making a transition toward smaller cells, two-hop
orthogonal frequency-division multiple access (OFDMA) relay networks have become a dominant, mandatory
component in the 4G standards (WiMAX802.16j, 3GPP LTE-Adv.). Here we are using the multicasting strategy
Given the growing importance of multimedia broadcast and multicast services (MBMS) in 4G networks, the
latter forms the focus of this project. The main aim of this project is to improve the performance of the OFDMA
based relay networks. The OFDMA transmission Scheme is a widely accepted scheme for improving the quality
and speed of communication over the 4G cellular network. There are two different models designed for OFDMA
relay networks .Distributed (DP) and Contiguous (CP) permutations. We are checking the performance of two
algorithms The linear programming algorithm and the greedy algorithm by using two models of OFDMA for
multicast scheduling and after performance evaluation we select the best model and the algorithm for
transmission. We further improve the throughput via retransmission of lost packets during data transfer over the
specified network. We can detect the packet loss by packet synchronization technique and a request will be sent
by the destination for re-sending the lost packets which is called as Re-Transmission.[1]
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).
Improving Power Efficiency in Cooperative Diversity and Mimo Systems by Using...IJERA Editor
In this paper, we propose a new simple relayingstrategy based on bit-interleaved convolutionally coded starquadrature amplitude modulation (QAM) along with coherent/ noncoherent detection. Exploiting this property, a hard limiter is used to enhance power amplifier (PA) efficiency at the relay.here we are using the higher order modulation for improving relay communication and also employ the accurate relay technique.Moreover, we show that the proposedapproach retains differential detectability, which results in a significant reduction of receiver complexity with robustness against phase ambiguityBy analyzing our proposed method in terms of asymptotic pairwise error probability(PEP),Furthermore, theeffectiveness of the proposed scheme in terms of PA efficiency is confirmed by comparing the statistical distributions of the corresponding instantaneous signal power.and also implement the PEP in MIMO systems for improving the power efficiency.All the theoretical results agree with those obtained by computer simulations.
Classical Discrete-Time Fourier TransformBased Channel Estimation for MIMO-OF...IJCSEA Journal
In this document, we look at various time domain channel estimation methods with this constraint of null carriers at spectrumborders.We showin detail howto gauge the importance of the “border effect” depending on the number of null carriers, which may vary from one system to another. Thereby we assess the limit of the technique discussed when the number of null carriers is large. Finally the DFT with the truncated singular value decomposition (SVD) technique is proposed to completely eliminate the impact of the null subcarriers whatever their number. A technique for the determination of the truncation threshold for any MIMO-OFDM system is also proposed.
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.
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.
EFFICIENCY ENHANCEMENT BASED ON ALLOCATING BIZARRE PEAKSijwmn
A new work has been proposed in this paper in order to overcome one of the main drawbacks that found in
the Orthogonal Frequency Division Multiplex (OFDM) systems, namely Peak to Average Power Ratio
(PAPR). Furthermore, this work will be compared with a previously published work that uses the neural
network (NN) as a solution to remedy this deficiency.
The proposed work could be considered as a special averaging technique (SAT), which consists of wavelet
transformation in its first stage, a globally statistical adaptive detecting algorithm as a second stage; and
in the third stage it replaces the affected peaks by making use of moving average filter process. In the NN
work, the learning process makes use of a previously published work that is based on three linear coding
techniques.
In order to check the proposed work validity, a MATLAB simulation has been run and has two main
variables to compare with; namely BER and CCDF curves. This is true under the same bandwidth
occupancy and channel characteristics. Two types of tested data have been used; randomly generated data
and a practical data that have been extracted from a funded project entitled by ECEM. From the achieved
simulation results, the work that is based on SAT shows promising results in reducing the PAPR effect
reached up to 80% over the work in the literature and our previously published work. This means that this
work gives an extra reduction up to 15% of our previously published work. However, this achievement will
be under the cost of complexity. This penalty could be optimized by imposing the NN to the SAT work in
order to enhance the wireless systems performance.
In recent past the influence of Radar has played a significant part in various fields. Radar sensing is one of
the prime application by which velocity and distance of a moving target can be found out. A joint RadCom
system to serve both radar sensing and wireless communication is proposed which ensures better
performance in terms of spectral efficiency, extended detection range and cost effectiveness. Such systems
demand for a common waveform which is designed in this work that perfectly matches to the system
requirements. OFDM multi carrier technique is chosen to generate a common waveform. Applicability of
multiple antenna technique for direction of arrival estimation is also considered. MIMO-OFDM technique
has gained much interest in the field of communication which improves the signal to noise ratio and lowers
the bit error rate. On the other hand the usage of MIMO reflects in the form of interference between
signals. In order to overcome this effect beamforming technique is used. In addition to theoretical
explanations we have also simulated and discussed the results for the proposed RadCom system using
MATLAB simulation tool.
A DDRESSING T HE M ULTICHANNEL S ELECTION , S CHEDULING A ND C OORDINATION...pijans
We discuss a new multichannel coordination and sche
duling challenge called the Multichannel Scheduling
Cost (MSC). It is caused by the inability of the co
ntrol channel to schedule simultaneous transmission
s
resulting in data channels lying idle and their ban
dwidth underutilized. As a result, wasted bandwidth
increases as the number of data channels increases.
To address this challenge, a cyclic scheduling
Algorithm (CSA) is proposed. It employs one dedicat
ed signaling channel and 4 data channels. It is
premised on a proactive channel reservation scheme
which reduces the idleness of channels. The scheme
ensures that data channels are reserved while they
are still busy. The data channels are reserved whil
e
their remaining transmission duration is equal to t
he virtual carrier sensing duration. This gives the
next
pair sufficient time to reserve the current data ch
annel before it becomes available, limiting the MSC
to the
first cycle. The simulation results show a performa
nce benefit of the CSA scheme in addressing the eff
ects
of the MSC
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.
Index modulation is one of the promising techniques for future communications systems due to many improvement over the classical orthogonal frequency division multiplexing systems such as single RF chain, increased throughput for the same modulation order, achieved tradeoff between the efficiencies of the power and the spectral, and elimination of inter-channel interference. Many forms of index modulation researches exist where symbols are conveyed in antennas, subcarriers, time slots, and the space-time matrix. Spatial modulation is one member of index modulation family where symbols are conveyed in activating transmit/receive antennas. In this paper, a modification to a standard multiple input single output scheme by integrating spatial modulation using simplified mathematical procedure is achieved. In the transmitter side, data and activation symbols are distributed simultaneously using mathematical module and floor functions. At the receiver, a simplified maximum likelihood detector is used to obtain transmitted pair of symbols. To verify this, MATLAB simulink is used to simulate a downlink system where spatial modulation is applied to a base station. Results for different transmit antenna number and modulation order are obtained in the form of bit error rate versus signal to noise ratio.
Peak to Average Power Ratio Reduction in Mc Cdma System by Using Pulse Shapin...IOSR Journals
Abstract: One of the drawback of multicarrier code division multiple access (MC CDMA) is the high peak to
average power ratio (PAPR). In this paper A novel scheme based on pulse shaping described for PAPR
reduction. Here three different pulse shaping filters (Raised cosine, Sinc power pulse and Nyqist pulse) are
described for PAPR reduction in MC CDMA system. The method is based on the proper selection of the pulses
for shaping the different sub carriers of the MC CDMA modulation scheme. It is shown by computer simulation
that the scheme achieves the significant improvement in PAPR reduction in MC CDMA system. Its
implementation complexity is much low in comparison to the previous published methods. Thus pulse shaping
technique can be used not only to shape the spectrum of the transmitted signal but also to reduce its PAPR. In
computer simulation It is observed that by using nyquist pulse near about 6.8 db PAPR is obtained. Which is
considerable PAPR reduction than a PAPR value of Original MC CDMA signal
Keywords: MC CDMA, PAPR, PULSE SHAPING, BPSK
An Approach to Improve the Quality of Service in OFDMA Relay Networks via Re-...iosrjce
With the next-generation cellular networks making a transition toward smaller cells, two-hop
orthogonal frequency-division multiple access (OFDMA) relay networks have become a dominant, mandatory
component in the 4G standards (WiMAX802.16j, 3GPP LTE-Adv.). Here we are using the multicasting strategy
Given the growing importance of multimedia broadcast and multicast services (MBMS) in 4G networks, the
latter forms the focus of this project. The main aim of this project is to improve the performance of the OFDMA
based relay networks. The OFDMA transmission Scheme is a widely accepted scheme for improving the quality
and speed of communication over the 4G cellular network. There are two different models designed for OFDMA
relay networks .Distributed (DP) and Contiguous (CP) permutations. We are checking the performance of two
algorithms The linear programming algorithm and the greedy algorithm by using two models of OFDMA for
multicast scheduling and after performance evaluation we select the best model and the algorithm for
transmission. We further improve the throughput via retransmission of lost packets during data transfer over the
specified network. We can detect the packet loss by packet synchronization technique and a request will be sent
by the destination for re-sending the lost packets which is called as Re-Transmission.[1]
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).
Improving Power Efficiency in Cooperative Diversity and Mimo Systems by Using...IJERA Editor
In this paper, we propose a new simple relayingstrategy based on bit-interleaved convolutionally coded starquadrature amplitude modulation (QAM) along with coherent/ noncoherent detection. Exploiting this property, a hard limiter is used to enhance power amplifier (PA) efficiency at the relay.here we are using the higher order modulation for improving relay communication and also employ the accurate relay technique.Moreover, we show that the proposedapproach retains differential detectability, which results in a significant reduction of receiver complexity with robustness against phase ambiguityBy analyzing our proposed method in terms of asymptotic pairwise error probability(PEP),Furthermore, theeffectiveness of the proposed scheme in terms of PA efficiency is confirmed by comparing the statistical distributions of the corresponding instantaneous signal power.and also implement the PEP in MIMO systems for improving the power efficiency.All the theoretical results agree with those obtained by computer simulations.
Classical Discrete-Time Fourier TransformBased Channel Estimation for MIMO-OF...IJCSEA Journal
In this document, we look at various time domain channel estimation methods with this constraint of null carriers at spectrumborders.We showin detail howto gauge the importance of the “border effect” depending on the number of null carriers, which may vary from one system to another. Thereby we assess the limit of the technique discussed when the number of null carriers is large. Finally the DFT with the truncated singular value decomposition (SVD) technique is proposed to completely eliminate the impact of the null subcarriers whatever their number. A technique for the determination of the truncation threshold for any MIMO-OFDM system is also proposed.
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.
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.
EFFICIENCY ENHANCEMENT BASED ON ALLOCATING BIZARRE PEAKSijwmn
A new work has been proposed in this paper in order to overcome one of the main drawbacks that found in
the Orthogonal Frequency Division Multiplex (OFDM) systems, namely Peak to Average Power Ratio
(PAPR). Furthermore, this work will be compared with a previously published work that uses the neural
network (NN) as a solution to remedy this deficiency.
The proposed work could be considered as a special averaging technique (SAT), which consists of wavelet
transformation in its first stage, a globally statistical adaptive detecting algorithm as a second stage; and
in the third stage it replaces the affected peaks by making use of moving average filter process. In the NN
work, the learning process makes use of a previously published work that is based on three linear coding
techniques.
In order to check the proposed work validity, a MATLAB simulation has been run and has two main
variables to compare with; namely BER and CCDF curves. This is true under the same bandwidth
occupancy and channel characteristics. Two types of tested data have been used; randomly generated data
and a practical data that have been extracted from a funded project entitled by ECEM. From the achieved
simulation results, the work that is based on SAT shows promising results in reducing the PAPR effect
reached up to 80% over the work in the literature and our previously published work. This means that this
work gives an extra reduction up to 15% of our previously published work. However, this achievement will
be under the cost of complexity. This penalty could be optimized by imposing the NN to the SAT work in
order to enhance the wireless systems performance.
In recent past the influence of Radar has played a significant part in various fields. Radar sensing is one of
the prime application by which velocity and distance of a moving target can be found out. A joint RadCom
system to serve both radar sensing and wireless communication is proposed which ensures better
performance in terms of spectral efficiency, extended detection range and cost effectiveness. Such systems
demand for a common waveform which is designed in this work that perfectly matches to the system
requirements. OFDM multi carrier technique is chosen to generate a common waveform. Applicability of
multiple antenna technique for direction of arrival estimation is also considered. MIMO-OFDM technique
has gained much interest in the field of communication which improves the signal to noise ratio and lowers
the bit error rate. On the other hand the usage of MIMO reflects in the form of interference between
signals. In order to overcome this effect beamforming technique is used. In addition to theoretical
explanations we have also simulated and discussed the results for the proposed RadCom system using
MATLAB simulation tool.
A DDRESSING T HE M ULTICHANNEL S ELECTION , S CHEDULING A ND C OORDINATION...pijans
We discuss a new multichannel coordination and sche
duling challenge called the Multichannel Scheduling
Cost (MSC). It is caused by the inability of the co
ntrol channel to schedule simultaneous transmission
s
resulting in data channels lying idle and their ban
dwidth underutilized. As a result, wasted bandwidth
increases as the number of data channels increases.
To address this challenge, a cyclic scheduling
Algorithm (CSA) is proposed. It employs one dedicat
ed signaling channel and 4 data channels. It is
premised on a proactive channel reservation scheme
which reduces the idleness of channels. The scheme
ensures that data channels are reserved while they
are still busy. The data channels are reserved whil
e
their remaining transmission duration is equal to t
he virtual carrier sensing duration. This gives the
next
pair sufficient time to reserve the current data ch
annel before it becomes available, limiting the MSC
to the
first cycle. The simulation results show a performa
nce benefit of the CSA scheme in addressing the eff
ects
of the MSC
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.
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.
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.
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.
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.
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.
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.
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.
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.
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
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.
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.
Similar to Performance Evaluation of PAPR Reduction with SER and BER by Modified Clipping & Filtering in 3GPP LTE Downlink (20)
Immunizing Image Classifiers Against Localized Adversary Attacksgerogepatton
This paper addresses the vulnerability of deep learning models, particularly convolutional neural networks
(CNN)s, to adversarial attacks and presents a proactive training technique designed to counter them. We
introduce a novel volumization algorithm, which transforms 2D images into 3D volumetric representations.
When combined with 3D convolution and deep curriculum learning optimization (CLO), itsignificantly improves
the immunity of models against localized universal attacks by up to 40%. We evaluate our proposed approach
using contemporary CNN architectures and the modified Canadian Institute for Advanced Research (CIFAR-10
and CIFAR-100) and ImageNet Large Scale Visual Recognition Challenge (ILSVRC12) datasets, showcasing
accuracy improvements over previous techniques. The results indicate that the combination of the volumetric
input and curriculum learning holds significant promise for mitigating adversarial attacks without necessitating
adversary training.
Event Management System Vb Net Project Report.pdfKamal Acharya
In present era, the scopes of information technology growing with a very fast .We do not see any are untouched from this industry. The scope of information technology has become wider includes: Business and industry. Household Business, Communication, Education, Entertainment, Science, Medicine, Engineering, Distance Learning, Weather Forecasting. Carrier Searching and so on.
My project named “Event Management System” is software that store and maintained all events coordinated in college. It also helpful to print related reports. My project will help to record the events coordinated by faculties with their Name, Event subject, date & details in an efficient & effective ways.
In my system we have to make a system by which a user can record all events coordinated by a particular faculty. In our proposed system some more featured are added which differs it from the existing system such as security.
Quality defects in TMT Bars, Possible causes and Potential Solutions.PrashantGoswami42
Maintaining high-quality standards in the production of TMT bars is crucial for ensuring structural integrity in construction. Addressing common defects through careful monitoring, standardized processes, and advanced technology can significantly improve the quality of TMT bars. Continuous training and adherence to quality control measures will also play a pivotal role in minimizing these defects.
Courier management system project report.pdfKamal Acharya
It is now-a-days very important for the people to send or receive articles like imported furniture, electronic items, gifts, business goods and the like. People depend vastly on different transport systems which mostly use the manual way of receiving and delivering the articles. There is no way to track the articles till they are received and there is no way to let the customer know what happened in transit, once he booked some articles. In such a situation, we need a system which completely computerizes the cargo activities including time to time tracking of the articles sent. This need is fulfilled by Courier Management System software which is online software for the cargo management people that enables them to receive the goods from a source and send them to a required destination and track their status from time to time.
COLLEGE BUS MANAGEMENT SYSTEM PROJECT REPORT.pdfKamal Acharya
The College Bus Management system is completely developed by Visual Basic .NET Version. The application is connect with most secured database language MS SQL Server. The application is develop by using best combination of front-end and back-end languages. The application is totally design like flat user interface. This flat user interface is more attractive user interface in 2017. The application is gives more important to the system functionality. The application is to manage the student’s details, driver’s details, bus details, bus route details, bus fees details and more. The application has only one unit for admin. The admin can manage the entire application. The admin can login into the application by using username and password of the admin. The application is develop for big and small colleges. It is more user friendly for non-computer person. Even they can easily learn how to manage the application within hours. The application is more secure by the admin. The system will give an effective output for the VB.Net and SQL Server given as input to the system. The compiled java program given as input to the system, after scanning the program will generate different reports. The application generates the report for users. The admin can view and download the report of the data. The application deliver the excel format reports. Because, excel formatted reports is very easy to understand the income and expense of the college bus. This application is mainly develop for windows operating system users. In 2017, 73% of people enterprises are using windows operating system. So the application will easily install for all the windows operating system users. The application-developed size is very low. The application consumes very low space in disk. Therefore, the user can allocate very minimum local disk space for this application.
Democratizing Fuzzing at Scale by Abhishek Aryaabh.arya
Presented at NUS: Fuzzing and Software Security Summer School 2024
This keynote talks about the democratization of fuzzing at scale, highlighting the collaboration between open source communities, academia, and industry to advance the field of fuzzing. It delves into the history of fuzzing, the development of scalable fuzzing platforms, and the empowerment of community-driven research. The talk will further discuss recent advancements leveraging AI/ML and offer insights into the future evolution of the fuzzing landscape.
Automobile Management System Project Report.pdfKamal Acharya
The proposed project is developed to manage the automobile in the automobile dealer company. The main module in this project is login, automobile management, customer management, sales, complaints and reports. The first module is the login. The automobile showroom owner should login to the project for usage. The username and password are verified and if it is correct, next form opens. If the username and password are not correct, it shows the error message.
When a customer search for a automobile, if the automobile is available, they will be taken to a page that shows the details of the automobile including automobile name, automobile ID, quantity, price etc. “Automobile Management System” is useful for maintaining automobiles, customers effectively and hence helps for establishing good relation between customer and automobile organization. It contains various customized modules for effectively maintaining automobiles and stock information accurately and safely.
When the automobile is sold to the customer, stock will be reduced automatically. When a new purchase is made, stock will be increased automatically. While selecting automobiles for sale, the proposed software will automatically check for total number of available stock of that particular item, if the total stock of that particular item is less than 5, software will notify the user to purchase the particular item.
Also when the user tries to sale items which are not in stock, the system will prompt the user that the stock is not enough. Customers of this system can search for a automobile; can purchase a automobile easily by selecting fast. On the other hand the stock of automobiles can be maintained perfectly by the automobile shop manager overcoming the drawbacks of existing system.
Overview of the fundamental roles in Hydropower generation and the components involved in wider Electrical Engineering.
This paper presents the design and construction of hydroelectric dams from the hydrologist’s survey of the valley before construction, all aspects and involved disciplines, fluid dynamics, structural engineering, generation and mains frequency regulation to the very transmission of power through the network in the United Kingdom.
Author: Robbie Edward Sayers
Collaborators and co editors: Charlie Sims and Connor Healey.
(C) 2024 Robbie E. Sayers
Performance Evaluation of PAPR Reduction with SER and BER by Modified Clipping & Filtering in 3GPP LTE Downlink
1. International Journal of Computer Science and Software Engineering (IJCSSE), Volume 1, Issue 1, October 2014
ISSN (Online): 2409-4285 www.IJCSSE.org Page: 14-22
Performance Evaluation of PAPR Reduction with SER and BER by
Modified Clipping & Filtering in 3GPP LTE Downlink
M. Y. Arafat1, S. Abd. Latif2, M. K. Alam3, S. S. Haque14, M. Akter5
1, 4 Department of ETE, RUET, Rajshahi-6204, Bangladesh
2, 3, 5 Department of Electrical and Computer Engineering, International Islamic University Malaysia,
Kuala Lumpur, Malaysia
1yeasir.ete.ruet09@gmail.com, 2suhaimie@iium.edu.my, 3shishir_lmu@yahoo.com,
4snikdho.ruet.ete.09@gmail.com, 5m.tethi@gmail.com
ABSTRACT
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).
Keywords: OFDM, LTE, Chevyshev, BER, Clipping and
Filtering(CF).
1. INTRODUCTION
One of the latest steps towards the 4th generation (4G) of
radio technologies is Long term evolution (LTE) which
has been designed to increase the capacity and speed of
mobile telephone networks. Data usage & voice
communication has grown fast now days in those networks
where 3GPP High Speed Packet Access (HSPA) was
introduced indicating that the users find using the network
connection like broadband wireless data. 3GPP Long Term
Evolution (LTE) has been designed to provide high data
capacity in data delivery at a comparatively lower cost.
But these services require highly reliable data transmission
over most of the time in very unfriendly environment.
Most of these transmission systems have to face much
degradation such as large noise, multipath, interference,
attenuation, nonlinearities, time variance and must meet
the finite constraints like crest factor & power limitation.
Most commonly used technique in multi-carrier
modulation is Orthogonal Frequency Division
Multiplexing (OFDM) which has become very popular in
wireless communication. But its large envelope fluctuation
which is quantified as Peak to Average Power Ratio
(PAPR) is the major disadvantage of OFDM transmission.
In order to operate in a perfectly linear region, the
operating power must be kept below the available power.
For this reason, power amplifier is used at the transmitter.
A lot of algorithms have been developed for the reduction
of this PAPR. All of them have their own advantages and
disadvantages [2]. Moreover, the data rate is reduced by
the Coding scheme which is undesirable. In case of
applying the Partial Transmit Sequence (PTS)[11] and
Selected Mapping (SLM) techniques, these are more
complex than that of CF technique. If another technique
named Tone Reservation (TR) is considered, it also allows
the data rate loss with more likelihood of increasing power.
As well as the techniques such as Active Constellation
Extension (ACE) and the Tone Injection (TI) [12] having
criteria of increasing power will be unexpected in case of
power constraint environment. The Selected Mapping is
one of the most commonly chosen techniques because of
its simplicity for implementation which bears no distortion
in the transmitted signal. It has been described first in [2]
i.e. to be known as the classical SLM technique which
contains one of the disadvantages like sending the extra
Side Information (SI) index along with the transmitted
OFDM signal. A special technique described in [1] can be
used to avoid this issue. However using complex matrix
sequence [13] doesn’t give the desired PAPR reduction.
2. 15
International Journal of Computer Science and Software Engineering (IJCSSE), Volume 1, Issue 1, October 2014
M. Y. Arafat et al.
In previous research works, a linear-phase FIR filter using
the Parks-McClellan algorithm was used in the composed
filtering [7]. Existing method [9] uses the band pass filter.
But, using our proposed special type of composed filter,
significant improvement was observed in the case of
PAPR reduction.
The rest of this paper is organized as follows: section 2
deals with basic OFDM technique and PAPR calculation,
Clipping and Filtering technique in section 3, section 4
proposed clipping and filtering technique, in section 4
explains design and simulation and this paper is concluded
with the last part.
2. BASIC OFDM TECHNIQUE AND PAPR
CALCULATION
Orthogonal Frequency Division Multiplexing (OFDM)
technique divides the frequency spectrum into sub-bands
small enough so that the channel effects are constant (flat)
over a given sub-band. After that a classical IQ (In phase
Quadrature phase) modulation QPSK, M-QAM, BPSK,
etc. are sent over the sub-band. If it can be designed
correctly, all the fast changing effects of the channel will
disappear during the transmission of a single symbol and
thus will be treated as flat fading at the receiver. OFDM is
a special form of multicarrier modulation (MCM) with
densely spaced subcarriers with overlapping spectra
allowing multiple-access. A large number of orthogonal
subcarriers are used to carry data which are closely spaced.
For each subcarrier, the data is divided into several parallel
data streams or channels. Each subcarrier is modulated
using a conventional modulation scheme like Phase Shift
Keying (PSK) or Quadrature Amplitude Modulation
(QAM) at a low symbol rate. In this case the total data rate
is to be maintained similar to that of the conventional
single carrier modulation scheme with the same bandwidth.
For achieving high data rate and combating with multipath
fading in Wireless Communications Orthogonal Frequency
Division Multiplexing (OFDM) is a promising technique.
It is a special form of multicarrier modulation which is
particularly suited for transmission over a dispersive
channel. The different carriers are totally independent of
one another which denotes that they are orthogonal to each
other. By placing the carrier exactly at the nulls in the
modulation spectra of each other these orthogonal carriers
can be achieved as shown in the following Figure 1. Each
carrier has an integer number of cycles over a symbol
period denoting the orthogonally of the carriers. The
spectrum of each carrier has a null at the centre frequency
of each of the other carriers in the system due to this
integer number of cycles which results in no interference
between the carriers that allows them to be spaced as close
as possible. The problem of overhead carrier spacing can
be recovered that is required in Frequency Division
Multiplexing (FDM). For bandwidth efficiency [4] this
multicarrier transmission scheme allows the overlapping
of the spectra of subcarriers.
Fig. 1. OFDM Spectrum
As a result of incidence of large number of independently
modulated sub-carriers in an OFDM system, as compared
to the average of the total system, the peak value of the
system may be very high. The coherent summation of N
signals having same phase produces a peak which is N
times the average signal [3]. In the design of both high
power amplifier (HPA) and digital-to-analog (DAC)
converter, PAPR is an vital factor in order to generate
almost error-free (minimum errors) transmitted OFDM
symbols.
In the transmitter, the linear power amplifiers are used in
order to make sure that the Q-point must be in the linear
region. The Q-point moves to the saturation region due to
the high PAPR resulting in the clipping of signal peaks
which generates in-band and out-off band distortion. The
dynamic range of the power amplifier should be increased
to keep the Q-point in the linear region which again
reduces its efficiency and enhances the cost. Hence a
trade-off exists between nonlinearity and efficiency. With
the incensement of this dynamic range, the cost of power
amplifier increases. As communication engineer our
objective undergoes investigating the comparative
performance analysis of different higher order modulation
techniques by using amplitude clipping & filtering based
design (signal distortion) to reduce PAPR.
The ratio between the maximum power & the average
power is defined for the envelope of a baseband complex
signal ̃(t) i.e.[2]
PAPR =
3. (1)
PAPR{̃(t) }= |̃()|
|̃()| (2)
For the complex pass band signal s(t) we can also write
this PAPR equation as follow:
PAPR{ s(t) } = |() |
|() | (3)
Now, equation (3) can be written as:
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M. Y. Arafat et al.
Fig. 2. Input Output characteristics of an HPA
PAPR{s(t) }= ()
!
= ()
∫
%
|() | $ (4)
Here, Pavg denotes the average power of the complex pass
band signal s(t) in the frequency domain it can be
computed because Inverse Fast Fourier Transform (IFFT)
is a unitary (scaled) transformation. For superior estimated
the PAPR of continuous time OFDM signals, the OFDM
signals samples are obtained by L times oversampling. The
time domain samples which are L times oversampled are
the NL point IFFT of the data block including (L-1)N
zero-padding. As a result, the oversampled IFFT output
can be expressed as the following equation:
X[n] = 1
,-.
/0 1
√ ) ((Σ +
2345
67 ) (5)
3. CLIPPING AND FILTERING
TECHNIQUE
For PAPR reduction in 3GPP LTE downlink system, one
of the easiest techniques which can be followed is
Amplitude Clipping of the signal and after that filtering the
signal. To do limit the peak envelope or amplitude of the
input signal a threshold value of the amplitude is made
fixed here [5].
The CR or clipping ratio is defined as below:
CR=
8 (6)
Here, P denotes the amplitude of the signal and σ denotes
the root mean squared value of the OFDM signal
(unclipped). The clipping function is performed in digital
time domain before the digital to analog (D/A) conversion
and the process is described by the following equation:
9:
=
9 9 ≤
1?∅(A) 9 (7)
where, 9:
is the clipped signal, the transmitted signal is
9, the amplitude and the phase of the transmitted signal,
9 is M and ∅(9) respestively.
4. PROPOSED CLIPPING AND
FILTERING TECHNIQUE
By indicating the second point of limitation [8], less BER
degradation can be obtained and that is clipped signal
passed through the band pass filter (BPF).
Clipped signal would pass through a high pass filter
(HPF) [7] was the phenomenon for the former designed
scheme for clipping filtering method. In the figure 3, the
proposed method is shown.
The input of the IFFT block is the interpolated signal
introducing
Q(Z −1) zeros in the middle of the original signal is
expressed as:
C′[] = FC[] GHI, 0 ≤ L ≤ M
N , OP − M
N L OP
0 , SLℎ1IUV1
(8)
The Z-times oversampled discrete-time signal is generated
in this system as the following equation:
W′[I] = 1
YXPO Σ C′[]1Z[
234Δ]
`M-. ^_
/0 ; r=0,1,…,Q(Z-1) (9)
After that the above over-sampled-discrete time signal gets
modulated with carrier frequency fc, yielding a pass band
signal Be’[r]
Fig. 3. Proposed Clipping and Filtering Block Diagram
[r] is the clipped version of Be’[r] which
Now, assuming W
is expressed as the following equation:
[r]=a
W
− Be′[r] ≤ −M
Be′[r] ⎸Be′[r]⎸
Be′[r] ≥ M
(10)
Here, the pre-specified clipping level is M. The signals are
passed through the proposed Composed Filter after
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International Journal of Computer Science and Software Engineering (IJCSSE), Volume 1, Issue 1, October 2014
M. Y. Arafat et al.
clipping. A set of FFT-IFFT operations are performed in
the filter, where after the FFT function the filtering
operation occurs in the frequency domain. The FFT
function transforms the clipped signal, W
[r] into the
[s]. The
frequency domain results in the term C
[s] are then passed through
information components of C
a high pass filter (HPF) generating Wh
[s]. This filtered
Wh
signal is then passed through the unchanged condition of
IFFT block. Here, the out-of-band radiation that fell in the
zeros is set back to zero. The signal is transformed in to
time domain by The IFFT block of the filter and thus
obtain [r]. After a low pass filtering our desired signal
is B’[r](s).
5. DESIGN AND SIMULATION
The observations were actually based on only QAM
modulation. Table 1 shows the values of parameters used
in the simulation for analysing the performance of clipping
and filtering technique. It can be seen from the simulations
results that it is possible for clipping and filtering scheme
to reduce peak to average power ratio (PAPR). Simulation
is done in the QAM modulation scheme i.e. 4-QAM has
been used in OFDM generation which is very effective
modulation techniques in 4G technologies having a
bandwidth conserving modulation technique. The number
of sub-carriers N is randomly having a sampling frequency
of FS= 8 MHz, satisfies the condition of orthogonality.
PAPR(dB) of the original OFDM is computed by
oversampling the number of sub-carriers K by the
oversampling factor of L=8 while L=4 is enough, by
insertion of (L-1) N zeros to reduce the ISI.
Complementary Cumulative Distribution Function
(CCDF) of PAPR is the measure of probability that how
much higher is the PAPR value in comparison to PAPR
(dB) is calculated by Monte-Carlo simulation.
Table 1: Parameter used for simulation
Bandwidth, BW 1 MHz
Over Sampling Factor, Z 8
Sampling Frequency, fs 1 MHz
Carrier Frequency, fc 12 MHz
Cyclic Prefix Size 16
No. of Subcarrier/FFT
256
Size, N
Clipping Ratio 0.6,0.8,1.0,1.2,1.4,1.6
Modulation 16-QAM
It can be seen from the simulations results that it is
possible for clipping and filtering scheme to reduce peak
to average power ratio (PAPR). Simulation is done in the
way, QAM modulation scheme i.e. 16-QAM has been
used in OFDM generation which is very effective
modulation techniques in 4G technologies having a
bandwidth conserving modulation technique. The number
of sub-carriers N is randomly having a sampling frequency
of FS = 8 MHz, satisfies the condition of orthogonality.
PAPR(db) of the original OFDM is computed by
oversampling the number of sub-carriers N by the
oversampling factor of Z=8 while Z=4 is enough, by
insertion of (Z-1) N zeros to reduce the ISI.
Complementary Cumulative Distribution Function
(CCDF) of PAPR is the measure of probability that how
much higher is the PAPR value in comparison to PAPR
(db) is calculated by Monte-Carlo simulation.
Figure 8 shows the existing PAPR calculation for filtering
and clipping and the BER performance.[10]
In Figure (3)-(7) is given the Random Signal Bits,
Modulated Signal(Transmitted),Received Signal, Scattered
Demodulated Signal Received Random bits for 16-
QAM. Figure (8) to (10) shows the unclipped and without
CP of Passband and Baseband signal before clipping and
filtering and after clipping filtering with proposed
filtering of the signal of different clipping ratio’s. Symbol
Error Rate of different QAM modulation and for 16-QAM
in simulated condition is given in Figure (17) to (18).
Figure 15 shows the PAPR reduction for proposed filtering
technique.
Fig. 3. Random Transmitted bits for 16-QAM
Fig. 4. Random Transmitted Symbols for 16-QAM
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International Journal of Computer Science and Software Engineering (IJCSSE), Volume 1, Issue 1, October 2014
M. Y. Arafat et al.
Fig. 5. Modulated Transmitted Signals for 16-QAM
Fig. 6. Received Signal for 16-QAM
Fig. 7. Signal after Demodulation for 16-QAM
a.
b.
c.
Fig. 8 a)Unclipped, b)Clipped, c)Clipped Filtering for CR=0.6
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International Journal of Computer Science and Software Engineering (IJCSSE), Volume 1, Issue 1, October 2014
M. Y. Arafat et al.
a.
b.
c.
Fig. 9. a)Unclipped, b)Clipped, c)Clipped Filtering for CR=0.8
a.
b.
c.
Fig. 10. a)Unclipped, b)Clipped, c)Clipped Filtering for CR=1.0
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International Journal of Computer Science and Software Engineering (IJCSSE), Volume 1, Issue 1, October 2014
M. Y. Arafat et al.
a.
b.
c.
Fig. 11. a)Unclipped, b)Clipped, c)Clipped Filtering for CR=1.2
a.
b.
c.
Fig. 12. a)Unclipped, b)Clipped, c)Clipped Filtering for CR=1.4
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International Journal of Computer Science and Software Engineering (IJCSSE), Volume 1, Issue 1, October 2014
M. Y. Arafat et al.
a.
b.
c.
Fig. 13. a)Unclipped, b)Clipped, c)Clipped Filtering for CR=1.6
Fig. 14. Existing Method for PAPR Reduction for clipping and Filtering
Fig. 15. Proposed Method for PAPR Reduction for clipping and Filtering
Fig. 16. BER performance by Proposed Method
Fig. 17. Symbol Error Rate for different M-ary QAM modulation
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International Journal of Computer Science and Software Engineering (IJCSSE), Volume 1, Issue 1, October 2014
M. Y. Arafat et al.
Fig. 18 Symbol Error Probability Curve for 16-QAM modulation
PAPR reduction (power gain in dB) by proposed method
is shown in Table 2
Table 2: PAPR reduction (power gain in dB) by proposed method
CR Previous Method Proposed
Method
0.6 9.2 6.45
0.8 9.35 6.9
1.0 9.5 7.65
1.2 9.6 8.0
1.4 9.9 8.5
1.6 10.2 9.0
6. CONCLUSION
Clipping and Filtering provides significant gains at
moderate additional complexity than SLMPTS and other
techniques. It is observed from the simulation that PAPR
of OFDMA is increasing while increase of subcarrier or
FFT size. However a tolerable BER is increased by the
proposed technique but reduced the PAPR for the OFDM
signal in a relatively higher rate. No power is increased
here and no data loss occurs. But it has a slight distortion
problem. It is believed that this filter can minimize the
PAPR and BER problem with clipping and filtering
method and can be used as alternative of the existing one
[7] for higher modulation FFT size.
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