Orthogonal frequency division multiplexing (OFDM) is a type of multicarrier modulation (MCM) technique in which larger bandwidth is divided into parallel narrow bands each of which is modulated by different subcarriers. All the subcarriers are orthogonal to each other and hence it reduces the interference among various subcarriers. OFDM technique is an efficient modulation technique used in certain wired and wireless application.In a wireless communication channel, the transmitted signal can travel from transmitter to receiver over multiple reflective paths. This results to multipath fading which causes fluctuations in amplitude, phase and angle of arrival of the received signal. For example, the signal which is transmitted from BTS (base transceiver station) may suffer multiple reflections from the buildings nearby, before reaching the mobile station. Such multipath fading channels are classified into slow fading/fast fading and frequency-selective/flat fading channels. This paper discusses the performance of OFDM system using various fading channels and channel coding. The parameter which is known as Bit error rate (BER) is calculated under different fading channels (AWGN, Rayleigh and Rician) for different digital modulation (BPSK, QPSK and QAM) and Channel coding (linear/Cyclic coding). Matlab Simulink tool is used to calculate the BER parameter.
COMPARISON OF BIT ERROR RATE PERFORMANCE OF VARIOUS DIGITAL MODULATION SCHEME...ijasa
Digital modulation increases information capacity, data security, and system availability while maintaining high communication quality. As a result, digital modulation techniques are in higher demand than analog modulation techniques due to their ability to transmit larger amounts of data. Amplitude Shift Keying (ASK), Frequency Shift Keying (FSK), Phase Shift Keying (PSK), Differential Phase Shift Keying (DPSK), and Quadrature Amplitude Modulation (QAM) are critical components of current communications systems development, particularly for broadband wireless communications. In this paper, the comparison of bit error rate performance of different modulation schemes (BPSK, QPSK, and16-QAM) and various equalization techniques such as constant modulus algorithm (CMA) and maximum likelihood sequence estimate (MLSE) for the AWGN and Rayleigh fading channels is analyzed using Simulink. BPSK outperforms QPSK and 16-QAM when compared to the other two digital modulation schemes. Among the three digital modulation schemes, BPSK is showing better performance as compared to QPSK and 16- QAM
PERFORMANCE EVALUATION OF BER FOR AWGN, AWGN MULTIPATH AND RAYLEIGH FADING CH...IJEEE
The objectives of this paper are to study, analyze and evaluate the performance of BER (Bit Error Rate) in mobile multipath fading propagation channel. The parameters which are considered for the performance evaluation are AWGN, AWGN Multipath, Rayleigh fading channel and Hadamard code generator.
Coverage of WCDMA Network Using Different Modulation Techniques with Soft and...ijcnac
The wideband code division multiple access (WCDMA) based 3G cellular mobile
wireless networks are expected to provide a diverse range of multimedia services to
mobile users with guaranteed quality of service (QoS). To serve diverse quality of service
requirements of these networks it necessitates new radio resource management strategies
for effective utilization of network resources with coding schemes. In this paper coverage
area for voice traffic and with different modulation techniques, coding schemes and
decision decoder are discussed. These discussions are to improve the coverage area in
the mobile communication system. This paper is mainly focuses on coverage area of
WCDMA system using link budget calculation with different modulation, coding schemes
and decision decoder. Simulation results demonstrate coverage extension for voice
service with different modulation,coding scheme, soft and hard decision decoder using
appropriate Bit error rate (BER) to maintain QoS of the voice.
The Mobile WiMAX simulation model is
implemented by using MATLAB code. The simulation model
consists of different phases which will help us to model the
transmitter and receiver section. In the next phase, the data is
being modulated by using the modulation methods QPSK and
QAM followed by OFDM transmitter. These phases can be
used to show the performance of these modulation methods
under varying condition. The Multipath Rician fading model is
implemented to introduce the fading in the transmitter data.
Receiver section is used to receive data from channel will be fed
into the OFDM demodulation. In the next phase, Fast Fourier
Transform is used to disassemble OFDM frame. After that
convolution encoding is applied to data and interleaving is
carried on by using MATLAB function. BPSK method is used
to change the data in the form of bit information to be symbols.
We had used
COMPARISON OF BIT ERROR RATE PERFORMANCE OF VARIOUS DIGITAL MODULATION SCHEME...ijasa
Digital modulation increases information capacity, data security, and system availability while maintaining high communication quality. As a result, digital modulation techniques are in higher demand than analog modulation techniques due to their ability to transmit larger amounts of data. Amplitude Shift Keying (ASK), Frequency Shift Keying (FSK), Phase Shift Keying (PSK), Differential Phase Shift Keying (DPSK), and Quadrature Amplitude Modulation (QAM) are critical components of current communications systems development, particularly for broadband wireless communications. In this paper, the comparison of bit error rate performance of different modulation schemes (BPSK, QPSK, and16-QAM) and various equalization techniques such as constant modulus algorithm (CMA) and maximum likelihood sequence estimate (MLSE) for the AWGN and Rayleigh fading channels is analyzed using Simulink. BPSK outperforms QPSK and 16-QAM when compared to the other two digital modulation schemes. Among the three digital modulation schemes, BPSK is showing better performance as compared to QPSK and 16- QAM
PERFORMANCE EVALUATION OF BER FOR AWGN, AWGN MULTIPATH AND RAYLEIGH FADING CH...IJEEE
The objectives of this paper are to study, analyze and evaluate the performance of BER (Bit Error Rate) in mobile multipath fading propagation channel. The parameters which are considered for the performance evaluation are AWGN, AWGN Multipath, Rayleigh fading channel and Hadamard code generator.
Coverage of WCDMA Network Using Different Modulation Techniques with Soft and...ijcnac
The wideband code division multiple access (WCDMA) based 3G cellular mobile
wireless networks are expected to provide a diverse range of multimedia services to
mobile users with guaranteed quality of service (QoS). To serve diverse quality of service
requirements of these networks it necessitates new radio resource management strategies
for effective utilization of network resources with coding schemes. In this paper coverage
area for voice traffic and with different modulation techniques, coding schemes and
decision decoder are discussed. These discussions are to improve the coverage area in
the mobile communication system. This paper is mainly focuses on coverage area of
WCDMA system using link budget calculation with different modulation, coding schemes
and decision decoder. Simulation results demonstrate coverage extension for voice
service with different modulation,coding scheme, soft and hard decision decoder using
appropriate Bit error rate (BER) to maintain QoS of the voice.
The Mobile WiMAX simulation model is
implemented by using MATLAB code. The simulation model
consists of different phases which will help us to model the
transmitter and receiver section. In the next phase, the data is
being modulated by using the modulation methods QPSK and
QAM followed by OFDM transmitter. These phases can be
used to show the performance of these modulation methods
under varying condition. The Multipath Rician fading model is
implemented to introduce the fading in the transmitter data.
Receiver section is used to receive data from channel will be fed
into the OFDM demodulation. In the next phase, Fast Fourier
Transform is used to disassemble OFDM frame. After that
convolution encoding is applied to data and interleaving is
carried on by using MATLAB function. BPSK method is used
to change the data in the form of bit information to be symbols.
We had used
A significant problem in Multicarrier Code Division Multiple Access (MC-
CDMA) system is the possibility of high Peak to Average Power Ratio (PAPR). This is due
to the cumulative sum of N subcarrier peaks in the transmitted signals which reduces Power
efficiency, resolution and battery life. In this paper a technique is proposed to make use of
Inverse Discrete Cosine Transform (IDCT) and Inverse Discrete Wavelet Transform
(IDWT) based Multicarrier Code Division Multiple Access (MC-CDMA) system. This
system is in combination with Modified Exponential Companding with Clipping Transform
(MECCT) technique which reduces PAPR and that is analyzed over Additive White
Gaussian Noise (AWGN) channel, Rayleigh and Stanford University Interim (SUI)
multipath fading channel.
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
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
COMPARISON OF BER AND NUMBER OF ERRORS WITH DIFFERENT MODULATION TECHNIQUES I...Sukhvinder Singh Malik
This paper provides analysis of BER and Number of Errors for MIMO-OFDM wireless communication system by using different modulation techniques. Wireless designers constantly seek to improve the spectrum efficiency/capacity, coverage of wireless networks, and link reliability. So the performances of the wireless communication systems can be enhanced by using multiple transmit and receive antennas, which is generally referred to as the MIMO technique. Here analysis will be carried out for an OFDM wireless communication system using different modulation techniques and considering the effect and the wireless channel like AWGN, fading. Performance results will be evaluated numerically and graphically using the plots of BER versus SNR and plots of number of errors versus SNR.
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
Generation of Orthogonal Minimum Correlation Spreading Code for CDMA Systemidescitation
Code Division Multiple Access (CDMA) is one of the
most promising tools for multiple access in future generation
wireless communication systems. In CDMA system, within
the specific bandwidth a large number of users could be served
by assigning specific code to each user. In this paper, an attempt
has been made to generate a novel orthogonal spreading code
to support a large number of users for CDMA system by
maintaining minimum correlation values between them. The
proposed “Orthogonal Minimum Correlation Spreading
Code” (OMCSC) would be able to provide a large number of
spreading codes by simultaneously reducing the effect of
M ultiple Access Interference (MAI) in CDM A system.
Moreover, the Bit Error Rate (BER) performance of the
proposed code has been compared with different existing codes
in order to establish the supremacy of the proposed code over
the others under multi-user scenario.
Cooperative Communication for a Multiple-Satellite Networkchiragwarty
when it comes to space communication
networks, there are many different kinds of space vehicles
that need to communicate with each other, in space as well
as with ground terminals and air borne platform. Example:
Geosynchronous Earth orbit (GEO), Low Earth Orbit
(LEO) satellites and UAVs. There is an ever growing
demand for higher data rates and minimal redundancy, with
satellites and various space platforms travelling at high
speeds relative to each other and relative to the ground
establishing such links can prove to be a real challenge
when Doppler Effect and line of sight (LOS) can play a
significant role in SONET timing and synchronization. As
the number of users grows the space communication links
need to address several types of coding and modulation.
This paper analyzes the use of cooperative communication
techniques for point-to-point and point-to-multipoint
communication links. To this end we start with a simplified
single relay model and proceed to analyze the multi-node
scenarios. We will then apply the amplify-and-forward,
decode-and-forward and coded cooperation protocols to the
best case scenario to compute the efficiency and
synchronization of the link. The single relay and multi-node
scenarios are evaluated on the basis of the signal to noise
(SNR) power received and inter channel interference (ICI).
The intention is to demonstrate the theoretical performance
by simulating outage probability versus spectral efficiency
for different relaying protocols. Subsequently we will show
the effect of cooperative communication on bandwidth
utilization for mobile satellites and space platforms.
Performance evaluation of 4-quadrature amplitude modulation over orthogonal ...IJECEIAES
Orthogonal frequency division multiplexing (OFDM) is a multicarrier modulation (MCM) technique that divides the wide bandwidth into parallel narrow bands, each of which is modulated by orthogonal subcarriers. Currently, OFDM is a high-spectral efficiency modulation technique that is used in a variety of wired and wireless applications. The transmitted signal in a wireless communication channel spreads from transmitter to receiver through multiple reflective paths. This triggers multipath fading, which causes variations in the received signal's amplitude and phase. Slow/fast and frequency-selective/frequency-nonselective are the main types of multipath fading channels. Therefore, in this paper, we proposed new models for modeling multipath fading channels, such as the exponential fading channel and the Gamma fading channel. In addition, new bit-error-rate (BER) derivations have been derived. The performance of the OFDM system over proposed channel models has been evaluated using Monte-Carlo simulation and compared to the Rayleigh fading channel model. The obtained results via simulations show that the exponential fading channel at a rate parameter (λ=0.5) outperforms the Rayleigh fading channel by 6 dB for all values of Eb/No, while the Gamma fading channel at (α=2) outperforms the Rayleigh fading channel by 3 dB for all values of Eb/No.
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.
A significant problem in Multicarrier Code Division Multiple Access (MC-
CDMA) system is the possibility of high Peak to Average Power Ratio (PAPR). This is due
to the cumulative sum of N subcarrier peaks in the transmitted signals which reduces Power
efficiency, resolution and battery life. In this paper a technique is proposed to make use of
Inverse Discrete Cosine Transform (IDCT) and Inverse Discrete Wavelet Transform
(IDWT) based Multicarrier Code Division Multiple Access (MC-CDMA) system. This
system is in combination with Modified Exponential Companding with Clipping Transform
(MECCT) technique which reduces PAPR and that is analyzed over Additive White
Gaussian Noise (AWGN) channel, Rayleigh and Stanford University Interim (SUI)
multipath fading channel.
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
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
COMPARISON OF BER AND NUMBER OF ERRORS WITH DIFFERENT MODULATION TECHNIQUES I...Sukhvinder Singh Malik
This paper provides analysis of BER and Number of Errors for MIMO-OFDM wireless communication system by using different modulation techniques. Wireless designers constantly seek to improve the spectrum efficiency/capacity, coverage of wireless networks, and link reliability. So the performances of the wireless communication systems can be enhanced by using multiple transmit and receive antennas, which is generally referred to as the MIMO technique. Here analysis will be carried out for an OFDM wireless communication system using different modulation techniques and considering the effect and the wireless channel like AWGN, fading. Performance results will be evaluated numerically and graphically using the plots of BER versus SNR and plots of number of errors versus SNR.
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
Generation of Orthogonal Minimum Correlation Spreading Code for CDMA Systemidescitation
Code Division Multiple Access (CDMA) is one of the
most promising tools for multiple access in future generation
wireless communication systems. In CDMA system, within
the specific bandwidth a large number of users could be served
by assigning specific code to each user. In this paper, an attempt
has been made to generate a novel orthogonal spreading code
to support a large number of users for CDMA system by
maintaining minimum correlation values between them. The
proposed “Orthogonal Minimum Correlation Spreading
Code” (OMCSC) would be able to provide a large number of
spreading codes by simultaneously reducing the effect of
M ultiple Access Interference (MAI) in CDM A system.
Moreover, the Bit Error Rate (BER) performance of the
proposed code has been compared with different existing codes
in order to establish the supremacy of the proposed code over
the others under multi-user scenario.
Cooperative Communication for a Multiple-Satellite Networkchiragwarty
when it comes to space communication
networks, there are many different kinds of space vehicles
that need to communicate with each other, in space as well
as with ground terminals and air borne platform. Example:
Geosynchronous Earth orbit (GEO), Low Earth Orbit
(LEO) satellites and UAVs. There is an ever growing
demand for higher data rates and minimal redundancy, with
satellites and various space platforms travelling at high
speeds relative to each other and relative to the ground
establishing such links can prove to be a real challenge
when Doppler Effect and line of sight (LOS) can play a
significant role in SONET timing and synchronization. As
the number of users grows the space communication links
need to address several types of coding and modulation.
This paper analyzes the use of cooperative communication
techniques for point-to-point and point-to-multipoint
communication links. To this end we start with a simplified
single relay model and proceed to analyze the multi-node
scenarios. We will then apply the amplify-and-forward,
decode-and-forward and coded cooperation protocols to the
best case scenario to compute the efficiency and
synchronization of the link. The single relay and multi-node
scenarios are evaluated on the basis of the signal to noise
(SNR) power received and inter channel interference (ICI).
The intention is to demonstrate the theoretical performance
by simulating outage probability versus spectral efficiency
for different relaying protocols. Subsequently we will show
the effect of cooperative communication on bandwidth
utilization for mobile satellites and space platforms.
Performance evaluation of 4-quadrature amplitude modulation over orthogonal ...IJECEIAES
Orthogonal frequency division multiplexing (OFDM) is a multicarrier modulation (MCM) technique that divides the wide bandwidth into parallel narrow bands, each of which is modulated by orthogonal subcarriers. Currently, OFDM is a high-spectral efficiency modulation technique that is used in a variety of wired and wireless applications. The transmitted signal in a wireless communication channel spreads from transmitter to receiver through multiple reflective paths. This triggers multipath fading, which causes variations in the received signal's amplitude and phase. Slow/fast and frequency-selective/frequency-nonselective are the main types of multipath fading channels. Therefore, in this paper, we proposed new models for modeling multipath fading channels, such as the exponential fading channel and the Gamma fading channel. In addition, new bit-error-rate (BER) derivations have been derived. The performance of the OFDM system over proposed channel models has been evaluated using Monte-Carlo simulation and compared to the Rayleigh fading channel model. The obtained results via simulations show that the exponential fading channel at a rate parameter (λ=0.5) outperforms the Rayleigh fading channel by 6 dB for all values of Eb/No, while the Gamma fading channel at (α=2) outperforms the Rayleigh fading channel by 3 dB for all values of Eb/No.
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.
BER Analysis of OFDM Systems with Varying Frequency Offset Factor over AWGN a...rahulmonikasharma
The progressively escalating demand for tremendously high rate data transmission over wireless mediums needsresourcefulconcord of electromagnetic resources considering restrictions like power incorporation, spectrum proficiency, robustness in disparity to multipath propagation and implementation complication. Orthogonal frequency division multiplexing (OFDM) is a favorable approach for upcoming generation wireless communication systems. However its susceptibility to the frequency offset triggered by frequency difference between local oscillator of transmitter and receiver or due to Doppler shift results to Inter Carrier Interference. This delinquent of ICI results inworsening performance of the wireless systems as bit error rate increaseswith increase in value of frequency offset. In this paper simulation results aredemonstratedfor analyzing the effect of varying frequency offset factor on system’s error rate performance.
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
The several assets for high-speed data transmission over wireless uses the Orthogonal Frequency Division
Multiplexing (OFDM) as it is a multicarrier transmission scheme. A large number of narrow bandwidth carriers is
therefore adopted by the OFDM. Individually for an OFDM, each subcarrier is attenuated under the frequency-selective
and fast fading channel, therefore the resulting gain is high attenuation which leads to poor performance of all OFDM
subcarriers if the same fixed transmission scheme are used. Thus the main goal of the indicated paper is to grab an
understanding of the inequality between fixed & adaptive modulations schemes as the introduction of the adaptive
modulation. The need for the above system is to make use of the speaker's voice to check their character and control
approach to administrations, for example, voice dialing data administrations, voice send, and security control for secret
data. The performance of paperwork basically states that implementation of adaptive modulation is done into blocks of
adjacent subcarriers which is the result of dividing whole subcarriers. Therefore the equivalent modulation scheme which
is the calculation of average instantaneous signal to noise (SNR) is exercised to entire subcarriers of the equal block. The
OFDM system average bit error rate (BER) performance is observed here under fixed modulation and adaptive
modulation, and these modulation techniques are recorded by accepting the different inverse fast Fourier transforms
(IFFT) size and uncomplicated adaptive Quadrature amplitude modulation (QAM) strategy. The simulation in MATLAB
shows the results as the performance of fixed modulation is inferior to that of the BER performance of OFDM system
using adaptive modulation. The prospective adaptive modulation and coding Technique uses OFDM to manage the fixed
BER under changing the channel.
Channel Estimation Techniques in MIMO-OFDM LTE SystemsCauses and Effects of C...IJERA Editor
There is an increasing demand for high data transmission rates with the evolution of the very large scale integration (VLSI) technology. The multiple input multiple output-orthogonal frequency division multiplexing (MIMO-OFDM) systems are used to fulfill these requirements because of their unique properties such as high spectral efficiency, high data rate and resistance towards multipath propagation. MIMO-OFDM systems are finding their applications in the modern wireless communication systems like IEEE 802.11n, 4G and LTE. They also offer reliable communication with the increased coverage area. The bottleneck to the MIMO-OFDM systems is the estimation of the channel state information (CSI). This can be estimated with the help of any one of the Training Based, Semiblind and Blind Channel estimation algorithms. This paper presents various channel estimation algorithms, optimization techniques and their effective utilization in MIMO-OFDM for modern wireless LTE systems.
Development And Implementation Of OFDM Transceiver For WLAN ApplicationsIJERA Editor
Multi-Carrier modulation is a technique for data transmission by multiplexing a low bit-rate data streams to modulated carriers into signal Wideband Carrier. Multi-Carrier transmission has a lot of useful properties such as delay-spread tolerance and spectrum efficiency that encourage their use in untethered broadband communication. OFDM is becoming the chosen modulation technique for wireless communications. OFDM is a multi-carrier modulation scheme with densely spaced sub-carriers that has gained a lot of popularity among the broadband community in the last few years. OFDM can provide large data rate with sufficient robustness to radio channel impairments. OFDM works on the principle of Orthogonality. The orthogonality between subcarriers which is at the core of OFDM modulation requires a perfect synchronization. OFDM has properties like high spectral efficiency, Resiliency to RF interference and Lower multi-path distortion. This work is concentrated in implementing both transmitter and receiver using Matlab software and also to verify whether the transmitted data is obtained at the receiver side. As we are using the OFDM technique we will be having bandwidth efficiency when compared to the normal FDM technique.
Designing and Performance Evaluation of 64 QAM OFDM SystemIOSR Journals
Abstract (11Bold) : — In this report, the performance analysis of 64 QAM-OFDM wireless communication
systems affected by AWGN in terms of Symbol Error Rate and Throughput is addressed. 64 QAM (64 ary
Quadrature Amplitude Modulation) is the one of the effective digital modulation technique as it is more power
efficient for larger values of M(64). The MATLAB script based model of the 64 QAM-OFDM system with
normal AWGN channel and Rayleigh fading channel has been made for study error performance and
throughput under different channel conditions. This simulated model maximizes the system throughput in the
presence of narrowband interference, while guaranteeing a SER below a predefined threshold. The SER
calculation is accomplished by means of modelling the decision variable at the receiver as a particular case of
quadratic form D in complex Gaussian random variables. Lastly comparative study of SER performance of 64
QAM-OFDM simulated & 64 QAM-OFDM theoretical under AWGN channel has been given. Also
performance of the system is given in terms of throughput (received bits/ofm symbol) is given in a plot for
different SNR. Keywords (11Bold) –64 QAM, BPSK, OFDM, PDF, SNR.
Designing and Performance Evaluation of 64 QAM OFDM SystemIOSR Journals
In this report, the performance analysis of 64 QAM-OFDM wireless communication
systems affected by AWGN in terms of Symbol Error Rate and Throughput is addressed. 64 QAM (64 ary
Quadrature Amplitude Modulation) is the one of the effective digital modulation technique as it is more power
efficient for larger values of M(64). The MATLAB script based model of the 64 QAM-OFDM system with
normal AWGN channel and Rayleigh fading channel has been made for study error performance and
throughput under different channel conditions. This simulated model maximizes the system throughput in the
presence of narrowband interference, while guaranteeing a SER below a predefined threshold. The SER
calculation is accomplished by means of modelling the decision variable at the receiver as a particular case of
quadratic form D in complex Gaussian random variables. Lastly comparative study of SER performance of 64
QAM-OFDM simulated & 64 QAM-OFDM theoretical under AWGN channel has been given. Also
performance of the system is given in terms of throughput (received bits/ofm symbol) is given in a plot for
different SNR
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
This report discusses the planning Associate in
nursing the implementation of an OFDM system
in several information module schemes like MQPSK,
M-QAM. First, a short introduction is
provided by explaining the background and the
specification of the project. Then the report deals
with the system model, every block of the OFDM
system is represented (IFFT, FFT, Cyclic prefix,
modulation / reception, Channel estimation, bit
error rate). System design is analyzed. The
transmission techniques, further because the
system parameters for transmission and reception
are explained well. Finally, the results are
provided.
BER Performance of OFDM-QAM over AWGN and RICAIN Channels Using Error Correct...IJERA Editor
In this paper, the performance of OFDM - QAM system by using error correcting codes (Convolutional, Reed Solomon and Interleaving) schemes that are used to encode the data stream in wireless communications using AWGN and RICIAN channels has been reported here. OFDM is presented for wireless communications we curing basic OFDM and affined modulations, as well as techniques to improve the performance of OFDM for wireless communications. Various simulations are performed to detect the best BER performance of each of the QAM system; OFDM-QAM and OFDM-QAM with Error Correction and to use the best outcomes to model the OFDM-QAM, Their effect of improving the total BER can be noticed due to the benefits of OFDM-QAM with correcting codes.
Similar to Performance of OFDM System under Different Fading Channels and Channel Coding (20)
Square transposition: an approach to the transposition process in block cipherjournalBEEI
The transposition process is needed in cryptography to create a diffusion effect on data encryption standard (DES) and advanced encryption standard (AES) algorithms as standard information security algorithms by the National Institute of Standards and Technology. The problem with DES and AES algorithms is that their transposition index values form patterns and do not form random values. This condition will certainly make it easier for a cryptanalyst to look for a relationship between ciphertexts because some processes are predictable. This research designs a transposition algorithm called square transposition. Each process uses square 8 × 8 as a place to insert and retrieve 64-bits. The determination of the pairing of the input scheme and the retrieval scheme that have unequal flow is an important factor in producing a good transposition. The square transposition can generate random and non-pattern indices so that transposition can be done better than DES and AES.
Hyper-parameter optimization of convolutional neural network based on particl...journalBEEI
Deep neural networks have accomplished enormous progress in tackling many problems. More specifically, convolutional neural network (CNN) is a category of deep networks that have been a dominant technique in computer vision tasks. Despite that these deep neural networks are highly effective; the ideal structure is still an issue that needs a lot of investigation. Deep Convolutional Neural Network model is usually designed manually by trials and repeated tests which enormously constrain its application. Many hyper-parameters of the CNN can affect the model performance. These parameters are depth of the network, numbers of convolutional layers, and numbers of kernels with their sizes. Therefore, it may be a huge challenge to design an appropriate CNN model that uses optimized hyper-parameters and reduces the reliance on manual involvement and domain expertise. In this paper, a design architecture method for CNNs is proposed by utilization of particle swarm optimization (PSO) algorithm to learn the optimal CNN hyper-parameters values. In the experiment, we used Modified National Institute of Standards and Technology (MNIST) database of handwritten digit recognition. The experiments showed that our proposed approach can find an architecture that is competitive to the state-of-the-art models with a testing error of 0.87%.
Supervised machine learning based liver disease prediction approach with LASS...journalBEEI
In this contemporary era, the uses of machine learning techniques are increasing rapidly in the field of medical science for detecting various diseases such as liver disease (LD). Around the globe, a large number of people die because of this deadly disease. By diagnosing the disease in a primary stage, early treatment can be helpful to cure the patient. In this research paper, a method is proposed to diagnose the LD using supervised machine learning classification algorithms, namely logistic regression, decision tree, random forest, AdaBoost, KNN, linear discriminant analysis, gradient boosting and support vector machine (SVM). We also deployed a least absolute shrinkage and selection operator (LASSO) feature selection technique on our taken dataset to suggest the most highly correlated attributes of LD. The predictions with 10 fold cross-validation (CV) made by the algorithms are tested in terms of accuracy, sensitivity, precision and f1-score values to forecast the disease. It is observed that the decision tree algorithm has the best performance score where accuracy, precision, sensitivity and f1-score values are 94.295%, 92%, 99% and 96% respectively with the inclusion of LASSO. Furthermore, a comparison with recent studies is shown to prove the significance of the proposed system.
A secure and energy saving protocol for wireless sensor networksjournalBEEI
The research domain for wireless sensor networks (WSN) has been extensively conducted due to innovative technologies and research directions that have come up addressing the usability of WSN under various schemes. This domain permits dependable tracking of a diversity of environments for both military and civil applications. The key management mechanism is a primary protocol for keeping the privacy and confidentiality of the data transmitted among different sensor nodes in WSNs. Since node's size is small; they are intrinsically limited by inadequate resources such as battery life-time and memory capacity. The proposed secure and energy saving protocol (SESP) for wireless sensor networks) has a significant impact on the overall network life-time and energy dissipation. To encrypt sent messsages, the SESP uses the public-key cryptography’s concept. It depends on sensor nodes' identities (IDs) to prevent the messages repeated; making security goals- authentication, confidentiality, integrity, availability, and freshness to be achieved. Finally, simulation results show that the proposed approach produced better energy consumption and network life-time compared to LEACH protocol; sensors are dead after 900 rounds in the proposed SESP protocol. While, in the low-energy adaptive clustering hierarchy (LEACH) scheme, the sensors are dead after 750 rounds.
Plant leaf identification system using convolutional neural networkjournalBEEI
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Customized moodle-based learning management system for socially disadvantaged...journalBEEI
This study aims to develop Moodle-based LMS with customized learning content and modified user interface to facilitate pedagogical processes during covid-19 pandemic and investigate how teachers of socially disadvantaged schools perceived usability and technology acceptance. Co-design process was conducted with two activities: 1) need assessment phase using an online survey and interview session with the teachers and 2) the development phase of the LMS. The system was evaluated by 30 teachers from socially disadvantaged schools for relevance to their distance learning activities. We employed computer software usability questionnaire (CSUQ) to measure perceived usability and the technology acceptance model (TAM) with insertion of 3 original variables (i.e., perceived usefulness, perceived ease of use, and intention to use) and 5 external variables (i.e., attitude toward the system, perceived interaction, self-efficacy, user interface design, and course design). The average CSUQ rating exceeded 5.0 of 7 point-scale, indicated that teachers agreed that the information quality, interaction quality, and user interface quality were clear and easy to understand. TAM results concluded that the LMS design was judged to be usable, interactive, and well-developed. Teachers reported an effective user interface that allows effective teaching operations and lead to the system adoption in immediate time.
Understanding the role of individual learner in adaptive and personalized e-l...journalBEEI
Dynamic learning environment has emerged as a powerful platform in a modern e-learning system. The learning situation that constantly changing has forced the learning platform to adapt and personalize its learning resources for students. Evidence suggested that adaptation and personalization of e-learning systems (APLS) can be achieved by utilizing learner modeling, domain modeling, and instructional modeling. In the literature of APLS, questions have been raised about the role of individual characteristics that are relevant for adaptation. With several options, a new problem has been raised where the attributes of students in APLS often overlap and are not related between studies. Therefore, this study proposed a list of learner model attributes in dynamic learning to support adaptation and personalization. The study was conducted by exploring concepts from the literature selected based on the best criteria. Then, we described the results of important concepts in student modeling and provided definitions and examples of data values that researchers have used. Besides, we also discussed the implementation of the selected learner model in providing adaptation in dynamic learning.
Prototype mobile contactless transaction system in traditional markets to sup...journalBEEI
One way to prevent and reduce the spread of the covid-19 pandemic is through physical distancing program. This research aims to develop a prototype contactless transaction system using digital payment mechanisms and QR code technology that will be applied in traditional markets. The method used in the development of electronic market systems is a prototype approach. The application of QR code and digital payments are used as a solution to minimize money exchange contacts that are common in traditional markets. The results showed that the system built was able to accelerate and facilitate the buying and selling transaction process in traditional market environment. Alpha testing shows that all functional systems are running well. Meanwhile, beta testing shows that the user can very well accept the system that was built. The results of the study also show acceptance of the usefulness of the system being built, as well as the optimism of its users to be able to take advantage of this system both technologically and functionally, so its can be a part of the digital transformation of the traditional market to the electronic market and has become one of the solutions in reducing the spread of the current covid-19 pandemic.
Wireless HART stack using multiprocessor technique with laxity algorithmjournalBEEI
The use of a real-time operating system is required for the demarcation of industrial wireless sensor network (IWSN) stacks (RTOS). In the industrial world, a vast number of sensors are utilised to gather various types of data. The data gathered by the sensors cannot be prioritised ahead of time. Because all of the information is equally essential. As a result, a protocol stack is employed to guarantee that data is acquired and processed fairly. In IWSN, the protocol stack is implemented using RTOS. The data collected from IWSN sensor nodes is processed using non-preemptive scheduling and the protocol stack, and then sent in parallel to the IWSN's central controller. The real-time operating system (RTOS) is a process that occurs between hardware and software. Packets must be sent at a certain time. It's possible that some packets may collide during transmission. We're going to undertake this project to get around this collision. As a prototype, this project is divided into two parts. The first uses RTOS and the LPC2148 as a master node, while the second serves as a standard data collection node to which sensors are attached. Any controller may be used in the second part, depending on the situation. Wireless HART allows two nodes to communicate with each other.
Implementation of double-layer loaded on octagon microstrip yagi antennajournalBEEI
A double-layer loaded on the octagon microstrip yagi antenna (OMYA) at 5.8 GHz industrial, scientific and medical (ISM) Band is investigated in this paper. The double-layer consist of two double positive (DPS) substrates. The OMYA is overlaid with a double-layer configuration were simulated, fabricated and measured. A good agreement was observed between the computed and measured results of the gain for this antenna. According to comparison results, it shows that 2.5 dB improvement of the OMYA gain can be obtained by applying the double-layer on the top of the OMYA. Meanwhile, the bandwidth of the measured OMYA with the double-layer is 14.6%. It indicates that the double-layer can be used to increase the OMYA performance in term of gain and bandwidth.
The calculation of the field of an antenna located near the human headjournalBEEI
In this work, a numerical calculation was carried out in one of the universal programs for automatic electro-dynamic design. The calculation is aimed at obtaining numerical values for specific absorbed power (SAR). It is the SAR value that can be used to determine the effect of the antenna of a wireless device on biological objects; the dipole parameters will be selected for GSM1800. Investigation of the influence of distance to a cell phone on radiation shows that absorbed in the head of a person the effect of electromagnetic radiation on the brain decreases by three times this is a very important result the SAR value has decreased by almost three times it is acceptable results.
Exact secure outage probability performance of uplinkdownlink multiple access...journalBEEI
In this paper, we study uplink-downlink non-orthogonal multiple access (NOMA) systems by considering the secure performance at the physical layer. In the considered system model, the base station acts a relay to allow two users at the left side communicate with two users at the right side. By considering imperfect channel state information (CSI), the secure performance need be studied since an eavesdropper wants to overhear signals processed at the downlink. To provide secure performance metric, we derive exact expressions of secrecy outage probability (SOP) and and evaluating the impacts of main parameters on SOP metric. The important finding is that we can achieve the higher secrecy performance at high signal to noise ratio (SNR). Moreover, the numerical results demonstrate that the SOP tends to a constant at high SNR. Finally, our results show that the power allocation factors, target rates are main factors affecting to the secrecy performance of considered uplink-downlink NOMA systems.
Design of a dual-band antenna for energy harvesting applicationjournalBEEI
This report presents an investigation on how to improve the current dual-band antenna to enhance the better result of the antenna parameters for energy harvesting application. Besides that, to develop a new design and validate the antenna frequencies that will operate at 2.4 GHz and 5.4 GHz. At 5.4 GHz, more data can be transmitted compare to 2.4 GHz. However, 2.4 GHz has long distance of radiation, so it can be used when far away from the antenna module compare to 5 GHz that has short distance in radiation. The development of this project includes the scope of designing and testing of antenna using computer simulation technology (CST) 2018 software and vector network analyzer (VNA) equipment. In the process of designing, fundamental parameters of antenna are being measured and validated, in purpose to identify the better antenna performance.
Transforming data-centric eXtensible markup language into relational database...journalBEEI
eXtensible markup language (XML) appeared internationally as the format for data representation over the web. Yet, most organizations are still utilising relational databases as their database solutions. As such, it is crucial to provide seamless integration via effective transformation between these database infrastructures. In this paper, we propose XML-REG to bridge these two technologies based on node-based and path-based approaches. The node-based approach is good to annotate each positional node uniquely, while the path-based approach provides summarised path information to join the nodes. On top of that, a new range labelling is also proposed to annotate nodes uniquely by ensuring the structural relationships are maintained between nodes. If a new node is to be added to the document, re-labelling is not required as the new label will be assigned to the node via the new proposed labelling scheme. Experimental evaluations indicated that the performance of XML-REG exceeded XMap, XRecursive, XAncestor and Mini-XML concerning storing time, query retrieval time and scalability. This research produces a core framework for XML to relational databases (RDB) mapping, which could be adopted in various industries.
Key performance requirement of future next wireless networks (6G)journalBEEI
Given the massive potentials of 5G communication networks and their foreseeable evolution, what should there be in 6G that is not in 5G or its long-term evolution? 6G communication networks are estimated to integrate the terrestrial, aerial, and maritime communications into a forceful network which would be faster, more reliable, and can support a massive number of devices with ultra-low latency requirements. This article presents a complete overview of potential 6G communication networks. The major contribution of this study is to present a broad overview of key performance indicators (KPIs) of 6G networks that cover the latest manufacturing progress in the environment of the principal areas of research application, and challenges.
Noise resistance territorial intensity-based optical flow using inverse confi...journalBEEI
This paper presents the use of the inverse confidential technique on bilateral function with the territorial intensity-based optical flow to prove the effectiveness in noise resistance environment. In general, the image’s motion vector is coded by the technique called optical flow where the sequences of the image are used to determine the motion vector. But, the accuracy rate of the motion vector is reduced when the source of image sequences is interfered by noises. This work proved that the inverse confidential technique on bilateral function can increase the percentage of accuracy in the motion vector determination by the territorial intensity-based optical flow under the noisy environment. We performed the testing with several kinds of non-Gaussian noises at several patterns of standard image sequences by analyzing the result of the motion vector in a form of the error vector magnitude (EVM) and compared it with several noise resistance techniques in territorial intensity-based optical flow method.
Modeling climate phenomenon with software grids analysis and display system i...journalBEEI
This study aims to model climate change based on rainfall, air temperature, pressure, humidity and wind with grADS software and create a global warming module. This research uses 3D model, define, design, and develop. The results of the modeling of the five climate elements consist of the annual average temperature in Indonesia in 2009-2015 which is between 29oC to 30.1oC, the horizontal distribution of the annual average pressure in Indonesia in 2009-2018 is between 800 mBar to 1000 mBar, the horizontal distribution the average annual humidity in Indonesia in 2009 and 2011 ranged between 27-57, in 2012-2015, 2017 and 2018 it ranged between 30-60, during the East Monsoon, the wind circulation moved from northern Indonesia to the southern region Indonesia. During the west monsoon, the wind circulation moves from the southern part of Indonesia to the northern part of Indonesia. The global warming module for SMA/MA produced is feasible to use, this is in accordance with the value given by the validate of 69 which is in the appropriate category and the response of teachers and students through a 91% questionnaire.
An approach of re-organizing input dataset to enhance the quality of emotion ...journalBEEI
The purpose of this paper is to propose an approach of re-organizing input data to recognize emotion based on short signal segments and increase the quality of emotional recognition using physiological signals. MIT's long physiological signal set was divided into two new datasets, with shorter and overlapped segments. Three different classification methods (support vector machine, random forest, and multilayer perceptron) were implemented to identify eight emotional states based on statistical features of each segment in these two datasets. By re-organizing the input dataset, the quality of recognition results was enhanced. The random forest shows the best classification result among three implemented classification methods, with an accuracy of 97.72% for eight emotional states, on the overlapped dataset. This approach shows that, by re-organizing the input dataset, the high accuracy of recognition results can be achieved without the use of EEG and ECG signals.
Parking detection system using background subtraction and HSV color segmentationjournalBEEI
Manual system vehicle parking makes finding vacant parking lots difficult, so it has to check directly to the vacant space. If many people do parking, then the time needed for it is very much or requires many people to handle it. This research develops a real-time parking system to detect parking. The system is designed using the HSV color segmentation method in determining the background image. In addition, the detection process uses the background subtraction method. Applying these two methods requires image preprocessing using several methods such as grayscaling, blurring (low-pass filter). In addition, it is followed by a thresholding and filtering process to get the best image in the detection process. In the process, there is a determination of the ROI to determine the focus area of the object identified as empty parking. The parking detection process produces the best average accuracy of 95.76%. The minimum threshold value of 255 pixels is 0.4. This value is the best value from 33 test data in several criteria, such as the time of capture, composition and color of the vehicle, the shape of the shadow of the object’s environment, and the intensity of light. This parking detection system can be implemented in real-time to determine the position of an empty place.
Quality of service performances of video and voice transmission in universal ...journalBEEI
The universal mobile telecommunications system (UMTS) has distinct benefits in that it supports a wide range of quality of service (QoS) criteria that users require in order to fulfill their requirements. The transmission of video and audio in real-time applications places a high demand on the cellular network, therefore QoS is a major problem in these applications. The ability to provide QoS in the UMTS backbone network necessitates an active QoS mechanism in order to maintain the necessary level of convenience on UMTS networks. For UMTS networks, investigation models for end-to-end QoS, total transmitted and received data, packet loss, and throughput providing techniques are run and assessed and the simulation results are examined. According to the results, appropriate QoS adaption allows for specific voice and video transmission. Finally, by analyzing existing QoS parameters, the QoS performance of 4G/UMTS networks may be improved.
Welcome to WIPAC Monthly the magazine brought to you by the LinkedIn Group Water Industry Process Automation & Control.
In this month's edition, along with this month's industry news to celebrate the 13 years since the group was created we have articles including
A case study of the used of Advanced Process Control at the Wastewater Treatment works at Lleida in Spain
A look back on an article on smart wastewater networks in order to see how the industry has measured up in the interim around the adoption of Digital Transformation in the Water Industry.
Industrial Training at Shahjalal Fertilizer Company Limited (SFCL)MdTanvirMahtab2
This presentation is about the working procedure of Shahjalal Fertilizer Company Limited (SFCL). A Govt. owned Company of Bangladesh Chemical Industries Corporation under Ministry of Industries.
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.
TECHNICAL TRAINING MANUAL GENERAL FAMILIARIZATION COURSEDuvanRamosGarzon1
AIRCRAFT GENERAL
The Single Aisle is the most advanced family aircraft in service today, with fly-by-wire flight controls.
The A318, A319, A320 and A321 are twin-engine subsonic medium range aircraft.
The family offers a choice of engines
Water scarcity is the lack of fresh water resources to meet the standard water demand. There are two type of water scarcity. One is physical. The other is economic water scarcity.
Sachpazis:Terzaghi Bearing Capacity Estimation in simple terms with Calculati...Dr.Costas Sachpazis
Terzaghi's soil bearing capacity theory, developed by Karl Terzaghi, is a fundamental principle in geotechnical engineering used to determine the bearing capacity of shallow foundations. This theory provides a method to calculate the ultimate bearing capacity of soil, which is the maximum load per unit area that the soil can support without undergoing shear failure. The Calculation HTML Code included.
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.
Immunizing Image Classifiers Against Localized Adversary Attacks
Performance of OFDM System under Different Fading Channels and Channel Coding
1. Bulletin of Electrical Engineering and Informatics
ISSN: 2302-9285
Vol. 6, No. 1, March 2017, pp. 54~61, DOI: 10.11591/eei.v6i1.591 54
Received December 6, 2016; Revised February 6, 2017; Accepted February 20, 2017
Performance of OFDM System under Different Fading
Channels and Coding
Pratima Manhasa
1*
, M. K Sonib
2
1
Research Scholar, FET, ECE Dept, Manav Rachna International University, Faridabad
2
ED& Dean, FET, Manav Rachna International University, Faridabad
*Corresponding author, email: pratimamehak@gmail.com
1*
, ed.fet@mriu.edu.in
2
Abstract
Orthogonal frequency division multiplexing (OFDM) is a type of multicarrier modulation (MCM)
technique in which larger bandwidth is divided into parallel narrow bands each of which is modulated by
different subcarriers. All the subcarriers are orthogonal to each other and hence it reduces the interference
among various subcarriers. OFDM technique is an efficient modulation technique used in certain wired and
wireless application.In a wireless communication channel, the transmitted signal can travel from transmitter
to receiver over multiple reflective paths. This results to multipath fading which causes fluctuations in
amplitude, phase and angle of arrival of the received signal. For example, the signal which is transmitted
from BTS (base transceiver station) may suffer multiple reflections from the buildings nearby, before
reaching the mobile station. Such multipath fading channels are classified into slow fading/fast fading and
frequency-selective/flat fading channels. This paper discusses the performance of OFDM system using
various fading channels and channel coding. The parameter which is known as Bit error rate (BER) is
calculated under different fading channels (AWGN, Rayleigh and Rician) for different digital modulation
(BPSK, QPSK and QAM) and Channel coding (linear/Cyclic coding). Matlab Simulink tool is used to
calculate the BER parameter.
Keywords: Fading, Rayleigh, Rician, Linear, Cyclic, Bit error rate, Simulink
1. Introduction
OFDM is an efficient digital modulation technique which is widely used in both wired
and wireless communication system. For wired application it is used in DSL, ADSL and for
wireless application it is used in wireless LAN. It is a bandwidth efficient technique in which
larger bandwidth is divided into parallel narrow bands each of which is modulated by different
subcarriers. OFDM has high peak to average power ratio and synchronization errors. The
performance of BER is calculated by using different fading channel and channel coding [1].
1.1. Fading Channel
Fading generally is a signal loss either in amplitude or phase due to sudden changes in
Channel response. The fading is considered to be a random process which may vary with time,
geographical position or radio frequency. In wireless systems, fading may either be due to
multipath propagation, referred to as multipath induced fading, or due to shadowing from
obstacles affecting the wave propagation, sometimes referred to as shadow fading.Large scale
fading (Shadowing) concerns about large distances effect so, its affect appears clearly incase of
the displacement of either the Transmitter or the Receiver. Small scale fading is concerned
about very small changes in the position of Transmitter or receiver in order of the wavelength
[2]. A model is required to predict the effects of this fading accurately in order to mitigate it
effects. Some of the channels used to model multipath fading are:
1.1.1. AWGN Channel
An AWGN channel results in addition of white Gaussian noise to the signal that passes
through it. The AWGN Channel block adds white Gaussian noise to a real or complex input
signal. When the input signal is real, the AWGN channel block adds real Gaussian noise and
produces a real output signal. When the input signal is complex, this AWGN channel block adds
complex Gaussian noise and produces a complex output signal.
2. Bulletin of EEI ISSN: 2302-9285
Performance of OFDM System under Different Fading Channels and … (Pratima Manhasa)
55
1.1.2. Rayleigh Channel
Rayleigh fading is a model that can be used to describe the form of fading that occurs
when multipath propagation exists. In any terrestrial environment a radio signal will travel
through a number of different paths from the transmitter to the receiver. The clearest path is the
direct, or line of sight path [3]. The Rayleigh fading model can be used to analyze radio signal
propagation on a statistical basis. It operates best under conditions when there is no dominant
signal (e.g. direct line of sight signal) and in many instances cellular telephones being used in a
dense urban environment fall into this category. Other examples where no dominant path
generally exists are for ionospheric propagation where the signal reaches the receiver through a
huge number of individual paths. Propagation using tropospheric ducting also exhibits the same
patterns.
1.1.3. Rician Channel
Fading causes the signal to spread and become diffuse. The Rician Fading Channel block
implements a baseband simulation of a Rician fading propagation channel.This block is useful
for modeling mobile wireless communication systems when the transmitted signal can travel to
the receiver along a dominant line-of-sight or direct path.The K-factor parameter is used for
Rician distribution which represents the ratio between direct-path (unspread) power and diffuse
power. The ratio is expressed linearly, not in decibels. While the Gain parameter controls the
overall gain through the channel, the K-factor parameter controls the gain's partition into direct
and diffuse components.
1.2. Channel Coding
Source encoding is used to convert the message in the coded form to be transmitted
through the channel and channel encoding deals with source encoded message by introducing
some extra bits that will be used in the detecting & correcting error [5].
The channel encoding methods can be classified as:
a. Linear Block codes
Block code is a type of error correcting code in which “k” bits input data is used to
produce” n” bits of output data. It is notated as (n, k). Linear block codes are so named
because each code word in the set is a linear combination of a set of generator code words
[6]. Any message of k bits can be generated by multiplication of message vector by the
generator matrix to produce a code word vector that is n bits long shown in equation (1).The
product of m and G gives the code word generation.
Code word generation(C) is given as
C=m*G (1)
Where m is message and G is generator
It is shown in Figure 1
Figure 1. Representation of Linear Block Code
In linear block code, the message is divided into blocks of k bits. Each block is encoded
to a larger block of n bits. The n bit codeword includes message and parity bits. After this
the coded bits are modulated and sent over channel. The reverse procedure is done at the
receiver. The block diagram (Figure 2) represents the data bits (k bits) and after passing
through the channel encoder is converted into n bit codeword[7].
3. ISSN: 2089-3191
Bulletin of EEI Vol. 6, No. 1, March 2017 : 54 – 61
56
Figure 2. Block Diagram of Linear Block Code
b. Cyclic block codes
They can be easily implemented in hardware. They can be determined algebraically
and hence can be decoded in constant time. They are very useful in situations where the BER
of the channel is relatively low, bandwidth availability is limited in the transmission, and it is easy
to retransmit data [14].
2. Proposed Simulink Model
The simulink model for OFDM system using various fading channels (AWGN, Rayleigh
and Rician), channel coding (Linear/Cyclic) and various digital modulations (BPSK, QPSK and
QAM) has the following steps and it is shown in Figure 3.
1) Bernoulli binary generator is used to generate the input signal. After getting the input signal
various channel coding is applied. Then the channel coded input signal is mapped by using
various modulations (BPSK/QPSK and QAM).
2) The mapped output is modeled using Inverse Fast Fourier transform (IFFT).
3) The output of Inverse Fast Fourier transform is passed through the AWGN, Rayleigh and
Rician channel and then demodulation is done to calculate the BER parameter using Error
rate calculation [7].
Figure 3. Proposed Simulink Model Using Different Coding and Channel
2.1. Proposed OFDM model using AWGN Channel with Linear/Cyclic coding
The proposed simulink model using AWGN channel including different channel coding
is shown in Figure 4. In the given model Bernoulli binary generator is used to generate the input
signal and then different coding is applied (linear/cyclic). The coded output is modulated by
using different digital modulation. Inverse fast Fourier transform is applied on the modulated
output and then the signal is passed through AWGN channel and reverse operation is
performed at the receiver side.
4. Bulletin of EEI ISSN: 2302-9285
Performance of OFDM System under Different Fading Channels and … (Pratima Manhasa)
57
Figure 4. Proposed Simulink Model Using Different Coding and AWGN Channel
2.2. Proposed OFDM Model Using Rayleigh Channel with Linear/Cyclic Coding
The Proposed simulink model using Rayleigh fading channel using Linear/Cyclic coding
is shown in Figure 5. In the given model Bernoulli binary generator is used to generate the input
signal and then different coding is applied (linear/cyclic). The coded output is modulated by
using different digital modulation. Inverse fast Fourier transform is applied on the modulated
output and then the signal is passed through Rayleigh fading channel and reverse operation is
performed at the receiver side.
Figure 5. Proposed Simulink Model Using Different Coding and Rayleigh Channel
2.3. Proposed OFDM Model Using Rician Channel with Linear/Cyclic coding
The Proposed model using the Rician fading channel using Linear/Cyclic coding is
shown in Figure 6. In the given model Bernoulli binary generator is used to generate the input
signal and then different coding is applied (linear/cyclic). The coded output is modulated by
using different digital modulation. Inverse fast Fourier transform is applied on the modulated
output and then the signal is passed through Rician fading channel and reverse operation is
performed at the receiver side.
5. ISSN: 2089-3191
Bulletin of EEI Vol. 6, No. 1, March 2017 : 54 – 61
58
Figure 6. Proposed Simulink Model Using Different Coding and Rician Channel
3. Simulation Results
The simulation parameters which are used for the proposed work are given below:
Digital Modulation = BPSK, QPSK and QAM
Fading Channel= AWGN, Rayleigh and Rician
Channel coding= Linear, cyclic
The BER results of OFDM system using various fading channel and channel coding are
shown in Figures7-9. In Figure 7, the BER result using BPSK based system results in minimum
value of BER as compared to QPSK and QAM based system.
Figure 7. BER Results of OFDM System Using Different Coding and AWGN Channel
The BER results using BPSK modulation for Rayleigh channel coding is shown below in Figure
8. In case of Rayleigh fading channel , BPSK based OFDM system results in minimum value of
BER as compared with QPSK and QAM based system.
Figure 8. BER results of OFDM System Using Different Coding and Rayleigh Channel
6. Bulletin of EEI ISSN: 2302-9285
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The BER results using BPSK modulation for Rician channel coding is shown below in
Figure 9. In case of Rician fading channel, BPSK based OFDM system results in minimum
value of BER as compared with QPSK and QAM based system.
Figure 9. BER Results of OFDM System Using Different Coding and Rician Channel
The BER calculation of FFT based OFDM system for different channel coding and
fading channel are shown in below in Table 1, 2 and 3 and bar chart is represented in Figures
10, 11, and 12.
Table 1. BER results of FFT Based OFDM System with Different Fading Channels and without
Channel Coding
OFDM system with
different modulation
AWGN
channel
Rayleigh
Channel
Rician
Channel
BPSK 0.272 0.454 0
QPSK 0.3636 0.545 0.545
QAM 0.636 0.6363 0.909
The Table 1 compares the BER results of FFT based OFDM system without channel
coding for different fading channel. From Table 1, it is clear that using AWGN channel, the BER
results are minimum and BPSK modulation also results in minimum value of BER. So, the
BPSK modulation with AWGN channel results in reducing the value of BER. The bar chart for
Table 1 is shown in Figure 10.
Figure 10. BER Graph for Various Fading Channel and without Channel Coding
Table 2, represents the BER results for FFT based OFDM system using AWGN,
Rayleigh and Rician channel for linear coding. From the given Table 2, the results of BER for
AWGN channel for BPSK modulation are better as compared with Rayleigh and Rician. After
AWGN channel, the results of Rician channel is better than Rayleigh channel.
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Table 2. BER Results of FFT based OFDM System with Different Fading Channels and
Linear Coding
OFDM system with
different modulation
AWGN
channel
Rayleigh
Channel
Rician
Channel
BPSK 0 0.5 0
QPSK 0.0833 0.33 0
QAM 0.5833 0.916 0.916
The bar chart for above Table 2 is shown in Figure 11. The bar chart represents the
BER results for different fading channel with linear coding.
Figure 11. BER Graph for Various Fading Channel and Linear Channel Coding
Table 3, represents the BER results for FFT based OFDM system using AWGN,
Rayleigh and Rician channel for cyclic coding. From the given Table 3, the results of BER for
AWGN channel for BPSK modulation are better as compared with Rayleigh and Rician. After
AWGN channel, the results of Rician channel is better than Rayleigh channel.
Table 3. BER Results of FFT Based OFDM System with Different Fading Channels and
cyclic Coding
OFDM system with
different modulation
AWGN
channel
Rayleigh
Channel
Rician
Channel
BPSK 0.083 0.5 0
QPSK 0.083 0.166 0.083
QAM 0.416 0.916 0.916
The bar chart for above Table 3 is shown in Figure 12. The bar chart represents the
BER results for different fading channel with cyclic coding.
Figure 12. BER Graph for Various Fading Channel and cyclic Channel Coding
8. Bulletin of EEI ISSN: 2302-9285
Performance of OFDM System under Different Fading Channels and … (Pratima Manhasa)
61
Simulation results show that cyclic coding FFT based OFDM system results in minimum
value of BER as compared to Linear coding. For different fading channels, AWGN channel
results in minimum BER as compared to Rayleigh and Rician channel. The BER value using
Rayleigh channel is more than Rician and AWGN. The OFDM system using BPSK modulation
with cyclic coding and AWGN channel results in minimum BER.QPSK based OFDM system
using cyclic coding for AWGN and Rician fading channel results in the same value of BER but
has higher value of BER for Rayleigh channel. So in order to model FFT based OFDM system,
cyclic coding and AWGN channel results in minimum value of BER.
4. Conclusion
The performance of FFT based OFDM system using various channels and channel
coding is simulated using simulink model. The results show that the BER is better in AWGN
channel and worst in Rayleigh channel. Rician fading channel has better BER value than
Rayleigh but less than AWGN channel. The cyclic coding based OFDM system with AWGN
channel helps in reducing the BER value.
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