The document discusses a research paper on implementing Fast Fourier Transform (FFT) for a Digital Audio Broadcasting (DAB) system. The paper investigates several FFT implementations using a single butterfly architecture to minimize hardware requirements. It also describes partitioning memory into banks to increase bandwidth between memory and processing units. Implementation results show the approach works for the DAB channel demodulator and has advantages over previous solutions.
IJERA (International journal of Engineering Research and Applications) is International online, ... peer reviewed journal. For more detail or submit your article, please visit www.ijera.com
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.
Orthogonal Frequency Division Multiplexing, OFDM uses a large number of narrow sub-carriers for multi-carrier transmission to overcome the effect of multi path fading problem. LTE uses OFDM for the downlink, from base station to terminal to transmit the data over many narrow band careers of 180 KHz each instead of spreading one signal over the complete 5MHz career bandwidth. OFDM meets the LTE requirement for spectrum flexibility and enables cost-efficient solutions for very wide carriers with high peak rates.
The primary advantage of OFDM over single-carrier schemes is its ability to cope with severe channel conditions. Channel equalization is simplified. The low symbol rate makes the use of a guard interval between symbols affordable, making it possible to eliminate inter symbol interference (ISI).
In this paper, we discussed about LTE system throughput calculation for both TDD and FDD system.
3GPP LTE technology support both TDD and FDD multiplexing. The paper describes all the factors which affect the throughput like Bandwidth, Modulation, UE category and mulplexing. It also describes how we get throughput 300Mbps in DL and 75Mbps in UL and what are assumptions taken to calculate the same.
Paper describes the steps and formulae to calculate the throughput for FDD system for TDD Config 1 and Config 2.
The throughput calculations shown in this paper is theoretical and limited by the assumptions taken to calculate for calculations
IJERA (International journal of Engineering Research and Applications) is International online, ... peer reviewed journal. For more detail or submit your article, please visit www.ijera.com
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.
Orthogonal Frequency Division Multiplexing, OFDM uses a large number of narrow sub-carriers for multi-carrier transmission to overcome the effect of multi path fading problem. LTE uses OFDM for the downlink, from base station to terminal to transmit the data over many narrow band careers of 180 KHz each instead of spreading one signal over the complete 5MHz career bandwidth. OFDM meets the LTE requirement for spectrum flexibility and enables cost-efficient solutions for very wide carriers with high peak rates.
The primary advantage of OFDM over single-carrier schemes is its ability to cope with severe channel conditions. Channel equalization is simplified. The low symbol rate makes the use of a guard interval between symbols affordable, making it possible to eliminate inter symbol interference (ISI).
In this paper, we discussed about LTE system throughput calculation for both TDD and FDD system.
3GPP LTE technology support both TDD and FDD multiplexing. The paper describes all the factors which affect the throughput like Bandwidth, Modulation, UE category and mulplexing. It also describes how we get throughput 300Mbps in DL and 75Mbps in UL and what are assumptions taken to calculate the same.
Paper describes the steps and formulae to calculate the throughput for FDD system for TDD Config 1 and Config 2.
The throughput calculations shown in this paper is theoretical and limited by the assumptions taken to calculate for calculations
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.
Blind Channel Shortening for MIMO-OFDM System Using Zero Padding and Eigen De...ijsrd.com
This paper deals with multiple-input multiple-output (MIMO) broadband wireless communication systems, employing orthogonal frequency-division multiplexing (OFDM). In order to exploit the benefits of OFDM in highly frequency-selective channels, without any significant increase in receiver complexity, a channel shortening prefilter is inserted at the receiver. The main aim of inserting channel shorteners is to shorten the channel so that the main energy of the composite channel is concentrated within a duration smaller than the guard interval inserted while transmission. Thus by including channel shortening equalizers at the receiver the inter symbol interference or the inter block interference can be suppressed. The new approach proposed in this thesis is zero padding approach with Eigen decomposition approach. The advantages of the proposed approaches include immunity to delay spread, resistance to frequency selective fading and simple equalization. This shortening design is a blind one, i.e., a priori knowledge of the MIMO channel impulse response to be shortened is not required, and can be carried out in closed-form.
Design of Scalable FFT architecture for Advanced Wireless Communication Stand...IOSRJECE
Now a day’s numerous wireless communication standards have raised additional stringent requirements on each throughput and flexibility for FFT computation. Advanced wireless systems support multiple standards to satisfy the demands of user application necessities. A wireless system whereas supporting multiple standards should also satisfy performance necessities of these supported standards. Meeting performance requirements of multiple standards is a challenge while designing a system. Fast Fourier transformations, a kernel processing task in communication systems, are studied intensively for efficient software and hardware implementations. To design an efficient system, it's necessary to efficiently design its performance critical component. each system must meet stringent design parameters like high speed, low power, low area, low cost, high flexibility and high scalability, designing FFT processor to support multiple wireless standards whereas meeting the above such performance necessities is a difficult task. This paper proposed a highly efficient scalable architecture, software tools design, and design implementation. The reconstruction of the FFT computation flow is design into a scalable structure. The FFT can be easily expanded for any-point FFT computation. The various parameters satisfied the conditions, gives proper and efficient outputs as compare to other platforms.
Energy-Efficient Image Transmission over OFDM Channel Using Huffman Codingijsrd.com
In this paper, Energy efficient image transmission using Huffman coding over OFDM channel has been proposed, which combines wavelet-based image decomposition and Huffman coding. Wavelet image transform provides data decomposition in multiple levels of resolution, so the image can be divided into packets with different priorities. The consumed energy when DWT is applied is clearly lower compared to the case without DWT. Using Huffman coding scheme, compress the low frequency band. In the proposed scheme, lower-resolution version of the compressed image obtained via discrete wavelet transform (DWT) is used. And show that the proposed strategy (DWT with Huffman coding)is more energy efficient than previous work (DWT without Huffman coding).In addition show that error rate(BER) is low compared to existing system(DWT without Huffman coding).
The International Journal of Engineering and Science (The IJES)theijes
The International Journal of Engineering & Science is aimed at providing a platform for researchers, engineers, scientists, or educators to publish their original research results, to exchange new ideas, to disseminate information in innovative designs, engineering experiences and technological skills. It is also the Journal's objective to promote engineering and technology education. All papers submitted to the Journal will be blind peer-reviewed. Only original articles will be published.
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology
Performance evaluation on the basis of bit error rate for different order of ...ijmnct
Today, we have required to accommodate a large number of users under a single base station. This can be
possible only if we have some flexibility over the spectrum. Previously we have lots of multiplexing methods
to accommodate large number of signals in time and frequency domain. But now we have required to
accommodate a large number of users in the same bandwidth, without any fading over the received signal.
So, orthogonality can be maintained over the frequency response. This technology is now more popular in
the mobile communication domain, called Orthogonal Frequency Division Multiplexing (OFDM). Actually
user data can be converted into the parallel form and then they are modulated using digital modulation
techniques. Finally, they have followed by OFDM Modulator and cyclic prefix can be inserted into the
OFDM symbols. Here, I have worked on the measurement of Bit error rate for different modulation
techniques in OFDM technology. It has been considered that subchannel size is not constant. According to
that I have concluded the overall idea regarding the performance under OFDM technology.
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.
An efficient multi resolution filter bank based on da based multiplicationVLSICS Design
Multi-resolution filter bank (MRFB)-based on the fast filter bank design can be used for multiple resolution
spectrum sensing. MRFB overcomes the constraint of fixed sensing resolution in spectrum sensors based
on conventional discrete Fourier transform filter banks (DFTFB) without hardware re-implementation.
Multipliers have a greater impact on complexity and performance of the design because a large number of
constant multiplications are required in the multiplication of filter coefficients with the filter input.
Modified multiplier architecture Distributed Arithmetic(DA) is used to improve the efficiency
Pwm technique to overcome the effect ofIJCNCJournal
Many current communication systems suffer from performance degradation due to the high sensitivity to
high power peaks especially in the nonlinear devices. The author introduces a new concept based on the
Pulse Width Modulation (PWM), namely MIMO-OFDM system based PWM (MO-PWM) to overcome this
deficiency. Here, the peak-to-average power ratio (PAPR) problem in Orthogonal Frequency Division
Multiplexing (OFDM) technique is used as a criterion to check the validity of the proposed work.
Moreover, the proposed system work has been implemented over Field Programmable Gate Array (FPGA),
which is designed to characterize both of the complexity and the speed issues.
The systems performance based MO-PWM and validity have been checked based on a numerical analysis
and a conducted simulation. The simulation results show that the MO-PWM can clearly reduce the PAPR
values nevertheless the used OFDM systems’ specifications, and gives a promising results over some
techniques found in the literature, such as clipping, SLM and PTS under same bandwidth occupancy and
system’s specifications.
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.
Blind Channel Shortening for MIMO-OFDM System Using Zero Padding and Eigen De...ijsrd.com
This paper deals with multiple-input multiple-output (MIMO) broadband wireless communication systems, employing orthogonal frequency-division multiplexing (OFDM). In order to exploit the benefits of OFDM in highly frequency-selective channels, without any significant increase in receiver complexity, a channel shortening prefilter is inserted at the receiver. The main aim of inserting channel shorteners is to shorten the channel so that the main energy of the composite channel is concentrated within a duration smaller than the guard interval inserted while transmission. Thus by including channel shortening equalizers at the receiver the inter symbol interference or the inter block interference can be suppressed. The new approach proposed in this thesis is zero padding approach with Eigen decomposition approach. The advantages of the proposed approaches include immunity to delay spread, resistance to frequency selective fading and simple equalization. This shortening design is a blind one, i.e., a priori knowledge of the MIMO channel impulse response to be shortened is not required, and can be carried out in closed-form.
Design of Scalable FFT architecture for Advanced Wireless Communication Stand...IOSRJECE
Now a day’s numerous wireless communication standards have raised additional stringent requirements on each throughput and flexibility for FFT computation. Advanced wireless systems support multiple standards to satisfy the demands of user application necessities. A wireless system whereas supporting multiple standards should also satisfy performance necessities of these supported standards. Meeting performance requirements of multiple standards is a challenge while designing a system. Fast Fourier transformations, a kernel processing task in communication systems, are studied intensively for efficient software and hardware implementations. To design an efficient system, it's necessary to efficiently design its performance critical component. each system must meet stringent design parameters like high speed, low power, low area, low cost, high flexibility and high scalability, designing FFT processor to support multiple wireless standards whereas meeting the above such performance necessities is a difficult task. This paper proposed a highly efficient scalable architecture, software tools design, and design implementation. The reconstruction of the FFT computation flow is design into a scalable structure. The FFT can be easily expanded for any-point FFT computation. The various parameters satisfied the conditions, gives proper and efficient outputs as compare to other platforms.
Energy-Efficient Image Transmission over OFDM Channel Using Huffman Codingijsrd.com
In this paper, Energy efficient image transmission using Huffman coding over OFDM channel has been proposed, which combines wavelet-based image decomposition and Huffman coding. Wavelet image transform provides data decomposition in multiple levels of resolution, so the image can be divided into packets with different priorities. The consumed energy when DWT is applied is clearly lower compared to the case without DWT. Using Huffman coding scheme, compress the low frequency band. In the proposed scheme, lower-resolution version of the compressed image obtained via discrete wavelet transform (DWT) is used. And show that the proposed strategy (DWT with Huffman coding)is more energy efficient than previous work (DWT without Huffman coding).In addition show that error rate(BER) is low compared to existing system(DWT without Huffman coding).
The International Journal of Engineering and Science (The IJES)theijes
The International Journal of Engineering & Science is aimed at providing a platform for researchers, engineers, scientists, or educators to publish their original research results, to exchange new ideas, to disseminate information in innovative designs, engineering experiences and technological skills. It is also the Journal's objective to promote engineering and technology education. All papers submitted to the Journal will be blind peer-reviewed. Only original articles will be published.
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology
Performance evaluation on the basis of bit error rate for different order of ...ijmnct
Today, we have required to accommodate a large number of users under a single base station. This can be
possible only if we have some flexibility over the spectrum. Previously we have lots of multiplexing methods
to accommodate large number of signals in time and frequency domain. But now we have required to
accommodate a large number of users in the same bandwidth, without any fading over the received signal.
So, orthogonality can be maintained over the frequency response. This technology is now more popular in
the mobile communication domain, called Orthogonal Frequency Division Multiplexing (OFDM). Actually
user data can be converted into the parallel form and then they are modulated using digital modulation
techniques. Finally, they have followed by OFDM Modulator and cyclic prefix can be inserted into the
OFDM symbols. Here, I have worked on the measurement of Bit error rate for different modulation
techniques in OFDM technology. It has been considered that subchannel size is not constant. According to
that I have concluded the overall idea regarding the performance under OFDM technology.
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.
An efficient multi resolution filter bank based on da based multiplicationVLSICS Design
Multi-resolution filter bank (MRFB)-based on the fast filter bank design can be used for multiple resolution
spectrum sensing. MRFB overcomes the constraint of fixed sensing resolution in spectrum sensors based
on conventional discrete Fourier transform filter banks (DFTFB) without hardware re-implementation.
Multipliers have a greater impact on complexity and performance of the design because a large number of
constant multiplications are required in the multiplication of filter coefficients with the filter input.
Modified multiplier architecture Distributed Arithmetic(DA) is used to improve the efficiency
Pwm technique to overcome the effect ofIJCNCJournal
Many current communication systems suffer from performance degradation due to the high sensitivity to
high power peaks especially in the nonlinear devices. The author introduces a new concept based on the
Pulse Width Modulation (PWM), namely MIMO-OFDM system based PWM (MO-PWM) to overcome this
deficiency. Here, the peak-to-average power ratio (PAPR) problem in Orthogonal Frequency Division
Multiplexing (OFDM) technique is used as a criterion to check the validity of the proposed work.
Moreover, the proposed system work has been implemented over Field Programmable Gate Array (FPGA),
which is designed to characterize both of the complexity and the speed issues.
The systems performance based MO-PWM and validity have been checked based on a numerical analysis
and a conducted simulation. The simulation results show that the MO-PWM can clearly reduce the PAPR
values nevertheless the used OFDM systems’ specifications, and gives a promising results over some
techniques found in the literature, such as clipping, SLM and PTS under same bandwidth occupancy and
system’s specifications.
An Effective Approach for Colour Image Transmission using DWT Over OFDM for B...IJMTST Journal
Image transmission over the fading channels without degrading the perceptual quality is a challenging task while mitigating the power consumption in many fields such as broadband networks, mobile communications, Image sharing and video broadcasting. Also, it is not possible to resend the lost packets every time in many applications such as video broadcasting. Here, an effective approach for color image transmission has been proposed with power saving approach over OFDM system. Experimental results shows that the reception quality of received image is good enough with various peak signal to noise ratios also saved 60% of energy.
Design and implementation of DA FIR filter for bio-inspired computing archite...IJECEIAES
This paper elucidates the system construct of DA-FIR filter optimized for design of distributed arithmetic (DA) finite impulse response (FIR) filter and is based on architecture with tightly coupled co-processor based data processing units. With a series of look-up-table (LUT) accesses in order to emulate multiply and accumulate operations the constructed DA based FIR filter is implemented on FPGA. The very high speed integrated circuit hardware description language (VHDL) is used implement the proposed filter and the design is verified using simulation. This paper discusses two optimization algorithms and resulting optimizations are incorporated into LUT layer and architecture extractions. The proposed method offers an optimized design in the form of offers average miminimizations of the number of LUT, reduction in populated slices and gate minimization for DAfinite impulse response filter. This research paves a direction towards development of bio inspired computing architectures developed without logically intensive operations, obtaining the desired specifications with respect to performance, timing, and reliability.
EFFECTS OF FILTERS ON THE PERFORMANCE OF DVB-T RECEIVERijwmn
Digital Video Broadcasting-Terrestrial (DVB-T) is an international standard for digital television
services. Orthogonal Frequency Division Multiplexing (OFDM) is the core of this technology. OFDM
based system like DVB-T can handle multipath fading and hence it can minimize Inter Symbol
Interference (ISI). DVB-T has some limitations too namely large dynamic range of the signals and
sensitivity to frequency error. In order to overcome these limitations DVB-T receivers should be optimally
designed. In this paper we address the issues related to optimal DVB-T receiver design. There of several
signal processing units in a DVB-T receiver. A low-pass filter is one of them. In this paper, we consider
some classic filters namely Butterworth, Chebyshev, and elliptic in the DVB-T receiver. The effects of
different filters on the performances of DVB-T receiver have been investigated and compared in this
paper under AWGN channel condition
Channel Coding and Clipping in OFDM for WiMAX using SDRidescitation
Recent developments in broadband wireless
technology heightened the need for WiMAX which assures
high-speed data services. Mobile WiMAX is grounded on
orthogonal frequency division multiplexing/orthogonal
frequency division multiplexing Access (OFDM/OFDMA)
technology which is an increasing important technique in
LTE systems. This paper describes the OFDM transceiver
implementation using software-defined radio system (SDR).
A SDR is a radio communication system where elements have
been generally implemented in hardware are rather
implemented by software on a personal computer. In this paper,
the software part is realized using GNU Radio and the
hardware part is implemented using USRP N210. OFDM poses
a problem of a Peak to Average Power Ratio (PAPR) or high
crest factor. To stave off this problem either High Power
Amplifiers (HPAs) with large dynamic range or PAPR reduction
techniques are used. The former scheme raises cost of the
system, while the latter induces redundancy or distortion.
This paper presents a novel architecture (which combines
channel coding and clipping) for the PAPR reduction and
analyzes various parameters which effects the performance
of OFDM such as power spectral density, the crest factor and
BER. Channel coding part is framed of three steps
randomization, Forward Error Correction (FEC) and
interleaving. In clipping, certain threshold limits the
amplitude of time domain samples. Without filtering, clipping
causes out-of-band radiation. The paper analyzes the out band
radiation value (at 2.395 GHz) and PAPR reduction with respect
to clipping threshold value. This scheme is preferred because
of its lower complexity and hence would be cheaper to
implement than conventional reduction techniques.
Experimental results prove that the clipping method reduced
PAPR significantly as the number of clip and filtering level is
increased.
FPGA Based Power Efficient Chanalizer For Software Defined RadioIJMER
Multiple communication channel support in RF transmission, such as that in a Software Defined Radio (SDR) warrants the use of channelizers to extract required channels from the received RF frequency band and to perform follow-on baseband processing. This paper describes the process of channelization as it applies to low power and high-efficiency applications in wireless and Satellite Communications (SATCOM) domains. Smaller bandwidths and changing requirements of bandwidth calls for a programmable channel selection mechanism whereby channels and the resulting bandwidth can be selected based on target application, which is the primary principle in the Software Defined Radio based systems.
Orthogonal frequency-division multiplexing (OFDM)
[1] is a method of encoding digital data on multiple carrier
frequencies. OFDM[1] has developed into a popular scheme
for wideband digital communication, whether wireless or
over copper wires, used in applications such as digital television
and audio broadcasting, DSL Internet access, wireless networks,
powerline networks, and 4G mobile communications. In the
Several wireless standards such as IEEE 802.11a[2] and
HiperLAN2[3].The orthogonality of the subcarriers is no longer
maintained which results in ICI (Inter carrier Interference)[4]
.ICI reduction techniques achieve a better SNR and BER in
OFDM at zero phase noise variance . This technique will use a
large number of closely spaced orthogonal subcarriers to avoid
phase noise. It provides high data rates with sufficient robustness
to radio channel damages. A major problem in OFDM is carrier
frequency offset error between the transmitted and received
signals. Due to this the orthogonality of the subcarriers is no
longer maintained which results in ICI (Inter carrier
Interference). In this paper, we used the ICI self-cancellation
technique and reduced the ICI and improved the BER and SNR
we are also calculate the SNR=15db and 20db at different phase
noise variance.
INVESTIGATION OF UTRA FDD DATA AND CONTROL CHANNELS IN THE PRESENCE OF NOISE ...ijngnjournal
In this paper, the main aim is to design and simulate UTRA FDD control channel in the presence of noise and wireless channel by using FDD library/Matlab box set that can be used to design and implement some
systems. Moreover, a test and verification of the library is achieved with different channel models such as Additive White Gaussian Noise (AWGN), fading and moving channel models. FDD library are employed to design whole transmitter and receiver. Then we had tested AWGN channel and some other channel models.
Also we illustrated what are control channels DCCH and the other one as understanding the whole system. Moreover, the standards have been covered as well as implemented the whole transmit and receive chain plus the generation of DPCH, DPCCH channel. we had tested the performance against the AWGN noise.
Then we have studied different channel models that are defined in the standard, used the few of them like the fading channel and moving channel. We have tried to compare the performance in terms of Monte Carlo simulation by producing the BER curves. We have also change some channel parameters like phase, number of multipaths and we have tried to see the performance of the model in the presence of actual channel model.
International Journal of Engineering Inventions (IJEI) provides a multidisciplinary passage for researchers, managers, professionals, practitioners and students around the globe to publish high quality, peer-reviewed articles on all theoretical and empirical aspects of Engineering and Science.
LCL Filter for Grid Connected VSC Converter
Comprehensive analysis and modeling of the three-phase LCL filter for VSC converters, suitable for wind energy or photovoltaic applications.
Performance of Six-Pulse Line-Commutated Converter in DC Motor Drive ApplicationZunAib Ali
This paper presents the speed control of DC motor using six pulse controlled rectifier. The
conventional Proportional Integral (PI) control is used for firing angle control. The armature current is fed
back and compared with reference current representing desired speed values. The proposed system is
simulated using SimPowerSystem and Control System Matlab toolbox. The time domain plot of reference
and actual armature current are shown in results section. The results are satisfactory with deleterious effect
on input current. The frequency plot of input current is provided to show the harmonic contents, generated
as a result of control operation.
Sinusoidal PWM and Space Vector Modulation For Two Level Voltage Source Conve...ZunAib Ali
Complete detail of Sinusoidal PWM and Space Vector Modulation For Two Level Voltage Source Converter
Space Vector Modulation includes:
Switching states, space vector, space vector diagram, space vector and switching states relationship, Dwell time, switching sequence
A complete description of including circuit diagram, gain equation, features of Instrumentational amplifier , its working principle, applications, practical circuits, Proteus simulation and conclusion.
Uet, Peshawar Pakistan
Batch-06
Concept of energy transmission & distribution ZunAib Ali
Downlaod is NOW Allowed (08/06/2016)
for more help: email me at zunaib_91@yahoo.com
Purpose of Electrical Transmission System
Main Parts of Power System
One-Line Diagram of Generating Station
Main Parts of Generating Station
Components of a Transmission Line
Design of an Efficient FFT Processor ffor DAB System
1. Zunaib Ali Class No: 09
Answer the following questions with reference to Research Paper attached.
1. What is the application based on Fast Fourier Transform, describe it?
This paper describes the design of Fast Fourier Transform (FFT) for the Eureka-147
Digital Audio Broadcasting (DAB) system. Here, in this research paper several possible
FFT implementations based on the single butterfly architecture are investigate, including
an in-place memory structure, to minimize the hardware requirement.
In the paper, a unified approach toward partitioning the whole memory into several
banks is also described, so as to increase the equivalent memory bandwidth between the
memory unit and the butterfly unit, which can be implemented in either radix-2 or high-
radix arithmetic. Implementation results demonstrate the applicability of our work to the
targeted channel demodulator and the advantages over previous solutions adopted for
Digital Audio Broadcasting (DAB) system.
2. What is the problem based upon Fast Fourier Transform, describe it?
The Digital Audio Broadcasting (DAB) system, described in the European Eweka-147
standard, offers high-quality audio services, supports multimedia data to mobile
reception and might replace the traditional radio system.
Basically, two strategies are employed to implement the DAB receiver:
a. The DSP-based architecture and
b. The Application-Specific Integrated Circuit (ASIC-based) implementation
The former has the characteristics of maximum flexibility, ease of use and simple
programming, but it can only provide limited processing capability. On the contrary, the
ASIC-based implementation has the potentials of supporting real-time symbol decoding
and low-cost implementation.
An overview of DAB system in which the ISO/MPEG coding is adopted for source
coding and COFDM (Coded Orthogonal Frequency Division Multiplexing) for channel
coding and modulation, is shown in figure. After convolutional coding, the data is
interleaved in frequency for the fast information channel and in time as well as in
frequency for the main service channel, and the OFDM modulation is then performed.
OFDM stands for Orthogonal Frequency Division Multiplexing; it’s a technology that
1
2. Zunaib Ali Class No: 09
provides the operator to beat the challenges of Non-Line-of-Sight (NLOS) transmission
in the more efficient manner. In this paper, we focus on the design and implementation
of the channel demodulator, which essentially performs a Fast Fourier Transform (FFT)
because the two basic strategies discussed above have some limitations i.e. one provide
limited processing capability and other type have Lack of adequate design tools & have
not yet been subject to formal evaluation and comparative analysis. One major
disadvantage of the other two methods is size of distributed ram is too much large. So to
avoid all this FFT in implemented.
Figure 1: Digital Audio Broadcasting System
3. Why Fourier transform was necessary in that application, can the application be
analyzed in the time domain?
Fourier series as well as Fourier transform is an extremely powerful mathematical tool
that allows you to view your signals in a different domain, inside which several difficult
problems become very simple to analyze. First and foremost, a Fourier transform of a
signal tells you what frequencies are present in your signal and in what proportions.
Specific to this example, Fourier transform is very important because in digital audio
broadcasting the role of frequency is too much important, a miner difference in
frequency spectrum can cause distortion and inter symbol interference between two
frequency spectrums. Have we ever noticed that each of our phone's number buttons
sounds different when we press during a call and that it sounds the same for every phone
model? That's because they are each composed of two different sinusoids which can be
used to uniquely identify the button. When we use our phone to punch in combinations
to navigate a menu, the way that the other party knows what keys you pressed is by
doing a Fourier transform of the input and looking at the frequencies present. In the
same way like explained in mobile phone example the digital data is transmitted and
received using different frequency bands.
So in order to make Digital Audio Broadcasting possible, without interference and noise,
we must have to make use of correct band of frequency allotted. To do so we have to
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study the frequency spectrum of signals to be transmitted as carrier waves, for this we
have to use Fourier transforms to convert time-domain in to frequency-domain. So it is
obvious that this application cannot be analyzed in time domain because we will not be
able to tell that the signal consists of which frequency components. Hence make Fourier
transform necessary for its analysis.
4. How Fourier transform actually proves useful for that application?
The electromagnetic spectrum shows that for broadcasting we have to use specific
frequency bands or range of frequencies. So the digital data is transmitted and received
using different frequency bands. Only transferring the function to frequency domain
would have helped us to identify the correct band of frequencies. So FFT is useful in
converting time-domain to frequency-domain & hence making Digital Audio
Broadcasting possible, without interference and noise.
Figure 2: EM Spectrum.
5. Discuss any drawbacks encountered while using the Fourier transformation tool?
In general, two basic types of FFT architectures can be found in the literature:
a. The pipelined architecture (each stage consisting of a butterfly unit) and
b. The single butterfly architecture.
The main concern is the trade-off between hardware overhead and speed requirement.
Although the pipelined version can provide a higher throughput rate than the
conventional single butterfly implementation, we are still interested in the single
butterfly architecture because of the specifications of the channel demodulator as well as
the hardware considerations on the implementation of a DAB receiver.
For the single butterfly implementation, a basic problem arises is how to efficiently
arrange memory read/write accesses for the purposes of increasing its throughput rate.
The commonly used solutions include:
a. Use the high-radix implementation to reduce the total number of memory
accesses at the expense of increasing the arithmetic complexity, i.e., the hardware
requirement of a high-radix butterfly unit.
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4. Zunaib Ali Class No: 09
b. Partitioning the memory into several banks to allow concurrent accesses of
multiple data at the price of using a more complicated addressing scheme, which
might correspond to a higher routing area.
Other problem, for a butterfly unit without employing pipelining, the critical path is the
summation of the memory read operation, arithmetic operation, and memory write
operation. To increase the overall operational frequency, we divide the operations of the
butterfly unit into three different steps, each corresponding to a mentioned operation as
shown in Fig.3 Due to the in-place computation, we have to schedule the tasks assigned
to the pipelined butterfly unit such that no control hazard occurs during memory
accesses. A control hazard results from the conflict when the butterfly unit intends to
access more than two data in the same memory bank.
Figure 3: Radix-2 DIT Pipeline Butterfly Unit
6. Can you implement same application using any other transformation tool?
Based on the specifications of the channel demodulator of the DAB receiver, we show
that the single butterfly architecture FFT is suited for the DAB systems. Similarly, any
transformation tool that would have helped will be the one which helps in transformation
from time domain to frequency domain could be used. The continuous Fourier transform
could never been used here because simply we are dealing here with discrete frequencies
not analogue frequencies, so it will be safer to say that only DFT can be used here,
although Laplace transform also provides a way for transformation to frequency domain
but even that could not be used here because it is also for continuous values.
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5. Zunaib Ali Class No: 09
b. Partitioning the memory into several banks to allow concurrent accesses of
multiple data at the price of using a more complicated addressing scheme, which
might correspond to a higher routing area.
Other problem, for a butterfly unit without employing pipelining, the critical path is the
summation of the memory read operation, arithmetic operation, and memory write
operation. To increase the overall operational frequency, we divide the operations of the
butterfly unit into three different steps, each corresponding to a mentioned operation as
shown in Fig.3 Due to the in-place computation, we have to schedule the tasks assigned
to the pipelined butterfly unit such that no control hazard occurs during memory
accesses. A control hazard results from the conflict when the butterfly unit intends to
access more than two data in the same memory bank.
Figure 3: Radix-2 DIT Pipeline Butterfly Unit
6. Can you implement same application using any other transformation tool?
Based on the specifications of the channel demodulator of the DAB receiver, we show
that the single butterfly architecture FFT is suited for the DAB systems. Similarly, any
transformation tool that would have helped will be the one which helps in transformation
from time domain to frequency domain could be used. The continuous Fourier transform
could never been used here because simply we are dealing here with discrete frequencies
not analogue frequencies, so it will be safer to say that only DFT can be used here,
although Laplace transform also provides a way for transformation to frequency domain
but even that could not be used here because it is also for continuous values.
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6. Zunaib Ali Class No: 09
b. Partitioning the memory into several banks to allow concurrent accesses of
multiple data at the price of using a more complicated addressing scheme, which
might correspond to a higher routing area.
Other problem, for a butterfly unit without employing pipelining, the critical path is the
summation of the memory read operation, arithmetic operation, and memory write
operation. To increase the overall operational frequency, we divide the operations of the
butterfly unit into three different steps, each corresponding to a mentioned operation as
shown in Fig.3 Due to the in-place computation, we have to schedule the tasks assigned
to the pipelined butterfly unit such that no control hazard occurs during memory
accesses. A control hazard results from the conflict when the butterfly unit intends to
access more than two data in the same memory bank.
Figure 3: Radix-2 DIT Pipeline Butterfly Unit
6. Can you implement same application using any other transformation tool?
Based on the specifications of the channel demodulator of the DAB receiver, we show
that the single butterfly architecture FFT is suited for the DAB systems. Similarly, any
transformation tool that would have helped will be the one which helps in transformation
from time domain to frequency domain could be used. The continuous Fourier transform
could never been used here because simply we are dealing here with discrete frequencies
not analogue frequencies, so it will be safer to say that only DFT can be used here,
although Laplace transform also provides a way for transformation to frequency domain
but even that could not be used here because it is also for continuous values.
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