Abstract : WiMAX ("Worldwide Interoperability for Microwave Access") technology is developed to meet the growing demand of increased data rate and accessing the internet at high speeds. 802.16 family of standards is officially called Wireless MAN in IEEE. Orthogonal frequency division multiplexing (OFDM) is multicarrier modulation technique used in IEEE 802.16d (fixed WiMAX) communication standard. OFDM is used to increase data rate of wireless medium with higher spectral efficiency. The proposed work is to evaluate performance of IEEE Std 802.16d transceiver in MATLAB R2009b simulink environment. System performance evaluated using BER vs SNR for different modulation technique such as 4 QAM, 16 QAM, 64 QAM under different channel condition. Keywords — 802.16d, MATLAB, OFDM, wimax.
Performance Improvement of IEEE 802.22 WRAN Physical LayerIOSR Journals
The spectrum available for the wireless services is limited, the increased demand of wireless
application has put a lot of limitations on the utilization of available radio spectrum. For the efficient spectrum
utilization for wireless application IEEE 802.22 standard i.e. WRAN (Wireless Regional Area Network) is
developed which is based on cognitive radio technique that senses the free available spectrum. It allows sharing
of geographically unused channels allocated to the TV Broadcast Service, without interference.
In this paper we are evaluating the performance of WRAN over physical layer with QPSK, 16-QAM
and 64-QAM modulation with Convolution coding with code rate of 1/2, 2/3, 3/4, 5/6 and obtaining the BER
curves for rician channel. Simulation is performed in MATLAB
Performance Analysis of 802.lln MIMO OFDM TransceiverIJERA Editor
The increasing demand on real time application to achieve high throughput, reliable wireless system and network capacity for fourth generation wireless local area networks is to combine MIMO wireless technology with OFDM. Orthogonal Frequency Division Multiplexing (OFDM), which offers reliable high bit rate wireless system with reasonable low complexity. OFDM does provide large data rates with sufficient robustness to radio channel impairments. OFDM is a combination of modulation and multiplexing and are able to maximize spectral efficiency without causing adjacent channel interference. This paper first focuses on 802.11n standard, MIMO-OFDM system. This paper further reviews different work done on implementation of MIMO-OFDM transceiver for 802.11n standard.
The Performance Evaluation of IEEE 802.16 Physical Layer in the Basis of Bit ...IJCI JOURNAL
Fixed Broadband Wireless Access is a promising technology which can offer high speed data rate from transmitting end to customer end which can offer high speed text, voice, and video data. IEEE 802.16 WirelessMAN is a standard that specifies medium access control layer and a set of PHY layer to fixed and mobile BWA in broad range of frequencies and it supports equipment manufacturers due to its robust performance in multipath environment. Consequently WiMAX forum has adopted this version to develop the network world wide. In this paper the performance of IEEE 802.16 OFDM PHY Layer has been investigated by using the simulation model in Matlab. The Stanford University Interim (SUI) channel models are selected for the performance evaluation of this standard. The Ideal Channel estimation is considered in this work and the performance evaluation is observed in the basis of BER.
SDH (Synchronous Digital Hierarchy) & Its Architectureijsrd.com
The SDH (Synchronous Digital Hierarchy) tell us about transferring large amount of data over an same optical fiber and this document gives us the information about the structure and architecture of SDH.
Performance Improvement of IEEE 802.22 WRAN Physical LayerIOSR Journals
The spectrum available for the wireless services is limited, the increased demand of wireless
application has put a lot of limitations on the utilization of available radio spectrum. For the efficient spectrum
utilization for wireless application IEEE 802.22 standard i.e. WRAN (Wireless Regional Area Network) is
developed which is based on cognitive radio technique that senses the free available spectrum. It allows sharing
of geographically unused channels allocated to the TV Broadcast Service, without interference.
In this paper we are evaluating the performance of WRAN over physical layer with QPSK, 16-QAM
and 64-QAM modulation with Convolution coding with code rate of 1/2, 2/3, 3/4, 5/6 and obtaining the BER
curves for rician channel. Simulation is performed in MATLAB
Performance Analysis of 802.lln MIMO OFDM TransceiverIJERA Editor
The increasing demand on real time application to achieve high throughput, reliable wireless system and network capacity for fourth generation wireless local area networks is to combine MIMO wireless technology with OFDM. Orthogonal Frequency Division Multiplexing (OFDM), which offers reliable high bit rate wireless system with reasonable low complexity. OFDM does provide large data rates with sufficient robustness to radio channel impairments. OFDM is a combination of modulation and multiplexing and are able to maximize spectral efficiency without causing adjacent channel interference. This paper first focuses on 802.11n standard, MIMO-OFDM system. This paper further reviews different work done on implementation of MIMO-OFDM transceiver for 802.11n standard.
The Performance Evaluation of IEEE 802.16 Physical Layer in the Basis of Bit ...IJCI JOURNAL
Fixed Broadband Wireless Access is a promising technology which can offer high speed data rate from transmitting end to customer end which can offer high speed text, voice, and video data. IEEE 802.16 WirelessMAN is a standard that specifies medium access control layer and a set of PHY layer to fixed and mobile BWA in broad range of frequencies and it supports equipment manufacturers due to its robust performance in multipath environment. Consequently WiMAX forum has adopted this version to develop the network world wide. In this paper the performance of IEEE 802.16 OFDM PHY Layer has been investigated by using the simulation model in Matlab. The Stanford University Interim (SUI) channel models are selected for the performance evaluation of this standard. The Ideal Channel estimation is considered in this work and the performance evaluation is observed in the basis of BER.
SDH (Synchronous Digital Hierarchy) & Its Architectureijsrd.com
The SDH (Synchronous Digital Hierarchy) tell us about transferring large amount of data over an same optical fiber and this document gives us the information about the structure and architecture of SDH.
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
Simulation of IEEE 802.16e Physical LayerIOSR Journals
Abstract : Growth in technology has led to unprecedented demand for high speed Internet access. IEEE
802.16e (Mobile WiMAX) is a wireless communication standard with high data transfer rates and good
performance. It not only is efficient as compared to its counterpart technologies today (Wi-Fi and 3G), but also
lays the foundation for 4G mobile communication. In 4G wireless communication systems, bandwidth is a
precious resource, and service providers are continuously met with the challenge of accommodating more users
within a limited allocated bandwidth. To increase data rate of wireless medium with higher performance,
Mobile WiMAX uses Orthogonal Frequency Division Multiple Access (OFDMA). This paper describes the
simulation of the physical layer of IEEE 802.16e using Simulink in Matlab 7.0 (R2010a). The system
performance is evaluated considering the Signal to noise ratio (SNR) and Bit error rate (BER) parameters.
Keywords: 802.16e, OFDMA, Mobile WiMAX.
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.
Error Control and performance Analysis of MIMO-OFDM Over Fading ChannelsIOSR Journals
ABSTRACT: Multiple Input Multiple Output is a wireless technology that uses multiple transmitters and
receivers to transfer more data at the same time. Orthogonal Frequency Division Multiplexing, an FDM
modulation technique which splits the signal into multiple smaller sub-signals that are then transmitted
simultaneously at different frequencies to the receiver. OFDM technique spreads the data over number of
carriers which are at specific predefined frequencies. This reduces or eliminates the ISI. Forward error
correction or channel coding is a technique used for controlling errors in data transmission over unreliable or
noisy communication channels. The objective of our proposed paper is to implement the FEC into the MIMO
OFDM systems and its performance is analysed by using MATLAB over different fading channels. For
modulation it employs M-QAM which combines both ASK and PSK thereby enabling several bits to be
transmitted per symbol. The performance of MIMO-OFDM system is evaluated by BER Vs SNR when the bits
propagates through the different fading channels.
Keywords– OFDM, MIMO, QAM, FEC, BER.
Effective Pixel Interpolation for Image Super ResolutionIOSR Journals
In the near future, there is an eminent demand for High Resolution images. In order to fulfil this
demand, Super Resolution (SR) is an approach used to renovate High Resolution (HR) image from one or more
Low Resolution (LR) images. The aspiration of SR is to dig up the self-sufficient information from each LR
image in that set and combine the information into a single HR image. Conventional interpolation methods can
produce sharp edges; however, they are approximators and tend to weaken fine structure. In order to overcome
the drawback, a new approach of Effective Pixel Interpolation method is incorporated. It has been numerically
verified that the resulting algorithm reinstate sharp edges and enhance fine structures satisfactorily,
outperforming conventional methods. The suggested algorithm has also proved efficient enough to be applicable
for real-time processing for resolution enhancement of image. Statistical examples are shown to verify the claim.
Image fusion technology is also used to fuse two processed images obtained through the algorithm
Automatic DNA Sequence Generation for Secured Effective Multi -Cloud StorageIOSR Journals
Abstract: The main target of this paper is to propose an algorithm to implement data hiding in DNA sequences
to increase the confidentiality and complexity by using software point of view in cloud computing environments.
By utilizing some interesting features of DNA sequences, the implementation of a data hiding is applied in
cloud. The algorithm which has been proposed here is based on binary coding and complementary pair rules.
Therefore, DNA reference sequence is chosen and a secret data M is hidden into it as well. As result of applying
some steps, M´´´ is come out to upload to cloud environments. The process of identifying and extracting the
original data M, hidden in DNA reference sequence begins once clients decide to use data. Furthermore,
security issues are demonstrated to inspect the complexity of the algorithm. In addition, providing better privacy
as well as ensure data availability, can be achieved by dividing the user’s data block into data pieces and
distributing them among the available SPs in such a way that no less than a threshold number of SPs can take
part in successful retrieval of the whole data block. In this paper, we propose a secured cost-effective multicloud
storage (SCMCS) model in cloud computing which holds an economical distribution of data among the
available SPs in the market, to provide customers with data availability as well as secure storage.
Keywords: DNA sequence; DNA base pairing rules; complementary rules; DNA binary coding; cloud service
provider.
Computing net radiation from temperature variables: Improvising for under-res...IOSR Journals
Most weather stations at farms, schools and other research institutes in the developing world do not
have radiation sensors and this is usually attributed to high costs of these sensors. Net radiation as one
component of radiation is important in crop farming as it influences germination, different growth stages, water
demand, size and quality of yield among other things. This article seeks to demonstrate how a series of
mathematical equations with temperature as a key physical quantity can be used to estimate net radiation using
the basic minimum of resources affordable against readings from a standard net radiometer. To achieve this,
daily data of maximum and minimum temperatures for 20 days was used from an automated weather station at
Great Zimbabwe University in Zimbabwe. A standard CNR 1 net radiometer was installed at the station to give
direct net radiation readings for comparison with the computed readings. A correlation between the calculated
net radiation and the measured one gave 90.8% correspondents. Diurnal net radiation was following the
maximum temperature trends. The average cost of a net radiometer sensor was US$ 3.700 which can be too
high for an ordinary farmer or other small research institutes.
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
Simulation of IEEE 802.16e Physical LayerIOSR Journals
Abstract : Growth in technology has led to unprecedented demand for high speed Internet access. IEEE
802.16e (Mobile WiMAX) is a wireless communication standard with high data transfer rates and good
performance. It not only is efficient as compared to its counterpart technologies today (Wi-Fi and 3G), but also
lays the foundation for 4G mobile communication. In 4G wireless communication systems, bandwidth is a
precious resource, and service providers are continuously met with the challenge of accommodating more users
within a limited allocated bandwidth. To increase data rate of wireless medium with higher performance,
Mobile WiMAX uses Orthogonal Frequency Division Multiple Access (OFDMA). This paper describes the
simulation of the physical layer of IEEE 802.16e using Simulink in Matlab 7.0 (R2010a). The system
performance is evaluated considering the Signal to noise ratio (SNR) and Bit error rate (BER) parameters.
Keywords: 802.16e, OFDMA, Mobile WiMAX.
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.
Error Control and performance Analysis of MIMO-OFDM Over Fading ChannelsIOSR Journals
ABSTRACT: Multiple Input Multiple Output is a wireless technology that uses multiple transmitters and
receivers to transfer more data at the same time. Orthogonal Frequency Division Multiplexing, an FDM
modulation technique which splits the signal into multiple smaller sub-signals that are then transmitted
simultaneously at different frequencies to the receiver. OFDM technique spreads the data over number of
carriers which are at specific predefined frequencies. This reduces or eliminates the ISI. Forward error
correction or channel coding is a technique used for controlling errors in data transmission over unreliable or
noisy communication channels. The objective of our proposed paper is to implement the FEC into the MIMO
OFDM systems and its performance is analysed by using MATLAB over different fading channels. For
modulation it employs M-QAM which combines both ASK and PSK thereby enabling several bits to be
transmitted per symbol. The performance of MIMO-OFDM system is evaluated by BER Vs SNR when the bits
propagates through the different fading channels.
Keywords– OFDM, MIMO, QAM, FEC, BER.
Effective Pixel Interpolation for Image Super ResolutionIOSR Journals
In the near future, there is an eminent demand for High Resolution images. In order to fulfil this
demand, Super Resolution (SR) is an approach used to renovate High Resolution (HR) image from one or more
Low Resolution (LR) images. The aspiration of SR is to dig up the self-sufficient information from each LR
image in that set and combine the information into a single HR image. Conventional interpolation methods can
produce sharp edges; however, they are approximators and tend to weaken fine structure. In order to overcome
the drawback, a new approach of Effective Pixel Interpolation method is incorporated. It has been numerically
verified that the resulting algorithm reinstate sharp edges and enhance fine structures satisfactorily,
outperforming conventional methods. The suggested algorithm has also proved efficient enough to be applicable
for real-time processing for resolution enhancement of image. Statistical examples are shown to verify the claim.
Image fusion technology is also used to fuse two processed images obtained through the algorithm
Automatic DNA Sequence Generation for Secured Effective Multi -Cloud StorageIOSR Journals
Abstract: The main target of this paper is to propose an algorithm to implement data hiding in DNA sequences
to increase the confidentiality and complexity by using software point of view in cloud computing environments.
By utilizing some interesting features of DNA sequences, the implementation of a data hiding is applied in
cloud. The algorithm which has been proposed here is based on binary coding and complementary pair rules.
Therefore, DNA reference sequence is chosen and a secret data M is hidden into it as well. As result of applying
some steps, M´´´ is come out to upload to cloud environments. The process of identifying and extracting the
original data M, hidden in DNA reference sequence begins once clients decide to use data. Furthermore,
security issues are demonstrated to inspect the complexity of the algorithm. In addition, providing better privacy
as well as ensure data availability, can be achieved by dividing the user’s data block into data pieces and
distributing them among the available SPs in such a way that no less than a threshold number of SPs can take
part in successful retrieval of the whole data block. In this paper, we propose a secured cost-effective multicloud
storage (SCMCS) model in cloud computing which holds an economical distribution of data among the
available SPs in the market, to provide customers with data availability as well as secure storage.
Keywords: DNA sequence; DNA base pairing rules; complementary rules; DNA binary coding; cloud service
provider.
Computing net radiation from temperature variables: Improvising for under-res...IOSR Journals
Most weather stations at farms, schools and other research institutes in the developing world do not
have radiation sensors and this is usually attributed to high costs of these sensors. Net radiation as one
component of radiation is important in crop farming as it influences germination, different growth stages, water
demand, size and quality of yield among other things. This article seeks to demonstrate how a series of
mathematical equations with temperature as a key physical quantity can be used to estimate net radiation using
the basic minimum of resources affordable against readings from a standard net radiometer. To achieve this,
daily data of maximum and minimum temperatures for 20 days was used from an automated weather station at
Great Zimbabwe University in Zimbabwe. A standard CNR 1 net radiometer was installed at the station to give
direct net radiation readings for comparison with the computed readings. A correlation between the calculated
net radiation and the measured one gave 90.8% correspondents. Diurnal net radiation was following the
maximum temperature trends. The average cost of a net radiometer sensor was US$ 3.700 which can be too
high for an ordinary farmer or other small research institutes.
Reduction of Side Lobes by Using Complementary Codes for Radar ApplicationIOSR Journals
Abstract: The analysis of new types of Complementary direct sequence complex signals which have synthesized
with well – know code sequences like Barker, Walsh, Golay, and complementary codes. Build on the
autocorrelation function (ACF) and ambiguity function (AF) of signals, the numerical method estimates the
volume of side lobes separately for each signal. The results obtained show that the signals, which have a low
volume of side lobes, means of approximately zero in by using complementary codes with compare to different
codes.
Keywords: Ambiguity function, complementary codes, autocorrelation function etc.
Spectrophotometric determination of a few commercial drugs using NBS and Rhod...IOSR Journals
Simple, sensitive and selective methods are developed for the spectrophotometric determination of drugs, viz., Montelukast sodium, Prasugrel, Ondensetron, Rosuvastatin calcium, Amlodepine besylate based on their reactivity towards N- bromosuccinimide (NBS). The method involves the addition of excess NBS of known concentration in the presence of 1M HCl, reactants are allowed to react and the unreacted NBS is estimated by the measurement in the decrease in the absorbance of the Rhodamine-B dye (λmax 557nm). This method has been applied for the determination of drugs in their pure form as well as in tablet formulations
Evaluate the Performance and Emission using EGR (Exhaust gas recirculation) i...IOSR Journals
To study different paper related to exhaust gas recirculation on four stroke compression ignition
engine fuelled with diesel/methanol blend of 10:90, 20:80 and 30:70 of methanol to diesel respectively were
studied to evaluate the performance and emission of engine. The performance of diesel engine increase with
increase in compression ratio exhaust gas recirculation is a common way to control in-cylinder NOx production
and is used in most modern high speed direct injection diesel engines because it lowers oxygen concentration
and flame temperature of the working fluid in the combustion chamber. To study evaluate and performance with
different EGR rate with and without variable compression ratio. After studying all different papers to review the
result the output power and torque for diesel fuel is lower compared to methanol-diesel blended fuel at any
mixing ratio and because of EGR the NOx emission and exhaust gas temperature reduced but emissions of
particulate matter (PM), HC, and CO were found to have increased with usage of EGR in CI engine.
Five-Dimensional Cosmological Model with Time-Dependent G and Lamda for Const...IOSR Journals
In this paper we have consider five-dimensional cosmological model in presence of perfect fluid
source with time dependent G and .The Einstein field equations are solvable with the help of constant
deceleration parameter. Physical and kinematical properties of this model are investigated. It has been shown
that the solutions are comparable with recent observations. The behavior of gravitational constant,
cosmological constant, density, critical density and pressure is discussed for dust, radiation dominated and stiff matter of the Universe. It is also examined the behavior of gravitational constant and cosmological constant for expansion law and exponential law for stiff matter
Synthesis of substituted 1, 2, 4-triazole derivatives by Microwave irradiationIOSR Journals
Various substituted Triazole-Thiol containing different functional group have been synthesized by microwave method. The title product 1-[(3H-indol-2-ylamino) methyl]-4-phenyl-4, 5-dihydro-1H-1, 2, 4-triazole-3-thiol is synthesized by using amino benzothiazole. The final structures have been established on the basis of their chemical analysis and spectral data. All micro-wave synthesized compounds results into good yield as compared to conventional method of which fluoro substituted compound shows maximum yield.
Determination of the viability of an agricultural solid waste; corncob as an ...IOSR Journals
Solid waste management has been a serious challenge facing most nations especially the developing nations. In Nigeria most of the cities are littered with solid waste. Corn cob an agricultural waste during its season is found littered in places where they are sold. As a way of managing the waste generated by corn cob, this study was undertaken to ascertain its viability and utilization as an oil spill sorbent mop. The absorption and recoverability of crude oil and its fractions namely; petrol, kerosene and diesel was studied and compared with a standard, a conventional synthetic absorbent mat used in oil spill mop which was subjected to the same experimental condition as corn cob. The experiment was performed with crude oil and its fraction only and a mixture of crude oil and its fraction on water. The result of the study reveals that the synthetic absorbent mat absorbed about five (5) times of crude oil and its fraction more than corn cob and recovered about ten (10) of the absorbed oil more than corn cob. The synthetic absorbent mat did not absorb water while sorbing the oils on water whereas corn cob did. Increase in contact time between corn cob and the oils and synthetic absorbent mat and the oils had no effect in the quantity of oil absorbed.
Calcium Chloride Applications to Improve Fruit Quality on Bruised and Disease...IOSR Journals
The problems faced by producer canned of pineapple are the high of bruised which caused by the mechanical damage such as pressure, vibration during harvest, transport to the fruit processing and pathological damage caused by fruit diseases. The objective of research was to obtain the treatment time of CaCl2 applications and dosage of CaCl2 to improve the fruit quality of pineapple. This research used Split Plot Design and each treatment replicated 3 times. The main plot is time of CaCl2 applications that consists of three levels, thats are : 90 day after forcing (daf) (W90), 120 daf (W120) and twice time of CaCl2 applications on 90 and 120 daf (W90+120). The sub plot is dosage of CaCl2 that consists of three levels, thats are : 50 kg ha-1 (C50), 75 kg ha-1 (C75) and 100 kg ha-1 (C100). The results of research showed that the combined treatment twice time of CaCl2 applications on 90 and 120 day after forcing and dosage of CaCl2 100 kg ha-1 produces the calcium content on fruit is higher than the other combined treatments and produce the fruit texture, percentage of fruit diseases and percentage of bruised are lower than the other combined treatments
Effects Of Heat Source And Thermal Diffusion On An Unsteady Free Convection F...IOSR Journals
The present analysis is made to investigate the effects of heat source and thermal diffusion on an unsteady free convection flow along a porous vertical plate in a rotating system. The plate is subjected to constant heat and mass flux also. The problem is solved analytically and expressions for velocity. Energy and temperature profiles, skin friction and Nusselt number are obtained. The effects of different parameter entered in the problem are discussed on the primary and secondary velocities, temperature and concentration distributions, primary and secondary skin frictions and Nusselt number with the help of tables and graphs.
Thorny Issues of Stakeholder Identification and Prioritization in Requirement...IOSR Journals
Abstract: Identifying the stakeholder in requirement engineering process is one of the critical issues. It
performs a remarkable part for successful project completion. The software project largely depends on several
stakeholders. Stakeholder identification and prioritization is still a challenging part in the software development
life cycle. Most of the time, the stakeholders are treated with less importance during the software deployment.
Additionally, there is a lack of attempt to think about the right project stakeholder by the development team. In
maximum cases, the stakeholder identification technique is performed incorrectly and there is a lack of attempt
to mark out them with priority. Besides, there are so many limitations on the existing processes which are used
for identifying stakeholders and setting their priority. These limitations pose a negative impact on the
development of software project, which should be pointed out by giving deep concern on it. We are aiming to
focus on this typical fact, so that we can figure out the actual problem and current work on identifying
stakeholders and setting their priority.
Keywords: Stakeholders, Stakeholder Identification, Stakeholder Selection, Stakeholder
Prioritization, Stakeholder Value, Software Development
Best Approximation in Real Linear 2-Normed SpacesIOSR Journals
This pape r d e l i n e a t e s existence, characterizations and st rong unicity of best uniform
approximations in real linear 2-normed spaces.
AMS Su ject Classification: 41A50, 41A52, 41A99, 41A28.
Chitosan capped Silver nanoparticles used as Pressure sensorsIOSR Journals
In the present work, we report the synthesis and characterization of silver nanoparticles, capped with chitosan (biopolymer ). The majority of the particles produced in this way had sizes around 18 nm. Composite films of capped silver nanoparticles and chitosan polymer were studied to understand the charge transport under different pressure. Films of different compositions were prepared to measure current voltage curves across the film thickness. The results reveal that these materials exhibit electrical conductivity as predicted by the “classical theory of percolation”. Pressure dependent electrical conductivity and these composites can be explored to develop low cost pressure sensors.
Performance Improvement of IEEE 802.22 WRAN Physical LayerIOSR Journals
Abstract: The spectrum available for the wireless services is limited, the increased demand of wireless application has put a lot of limitations on the utilization of available radio spectrum. For the efficient spectrum utilization for wireless application IEEE 802.22 standard i.e. WRAN (Wireless Regional Area Network) is developed which is based on cognitive radio technique that senses the free available spectrum. It allows sharing of geographically unused channels allocated to the TV Broadcast Service, without interference. In this paper we are evaluating the performance of WRAN over physical layer with QPSK, 16-QAM and 64-QAM modulation with Convolution coding with code rate of 1/2, 2/3, 3/4, 5/6 and obtaining the BER curves for rician channel. Simulation is performed in MATLAB. Keywords - CC, CP, CR, OFDMA, PHY Layer, WRAN
Performance Improvement of IEEE 802.22 WRAN Physical LayerIOSR Journals
Abstract: The spectrum available for the wireless services is limited, the increased demand of wireless
application has put a lot of limitations on the utilization of available radio spectrum. For the efficient spectrum
utilization for wireless application IEEE 802.22 standard i.e. WRAN (Wireless Regional Area Network) is
developed which is based on cognitive radio technique that senses the free available spectrum. It allows sharing
of geographically unused channels allocated to the TV Broadcast Service, without interference.
In this paper we are evaluating the performance of WRAN over physical layer with QPSK, 16-QAM
and 64-QAM modulation with Convolution coding with code rate of 1/2, 2/3, 3/4, 5/6 and obtaining the BER
curves for rician channel. Simulation is performed in MATLAB.
Keywords - CC, CP, CR, OFDMA, PHY Layer, WRAN
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.
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
Performance Evaluation and Simulation of OFDM in Optical Communication SystemsIJERA Editor
Orthogonal Frequency Division Multiplexing (OFDM) is of prime importance nowadays in long haul
communication networks because of its higher spectral efficiency, immunity to multipath fading and its
resilience to interference. Optical Orthogonal Frequency Division Multiplexing is considered as a promising
technology to satisfy the increased demand for bandwidth in broadband services. It is of two types based on the
detection techniques employed. They are direct detection and coherent detection. In direct detection OFDM, a
photodiode is used while in the latter the principle of optical mixing is utilized. This paper investigates the
architecture of single channel and four channel direct detection and coherent detection optical OFDM systems
and carries out performance analysis based on bit error rate and Q-factor. In the case of single channels, a date
rate of 10 Gbps is achieved while in 4 channel systems a data rate of 40 Gbps is achieved. Coherent Optical
OFDM (CO-OFDM) is the next generation technology for the optical communications, since it integrates the
advantages of both coherent systems and OFDM systems.
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IOSR Journal of Electronics and Communication Engineering(IOSR-JECE) is an open access international journal that provides rapid publication (within a month) of articles in all areas of electronics and communication engineering and its applications. The journal welcomes publications of high quality papers on theoretical developments and practical applications in electronics and communication engineering. Original research papers, state-of-the-art reviews, and high quality technical notes are invited for publications.
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.
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Growth in technology has led to unprecedented demand for high speed architectures for complex signal processing applications. In 4G wireless communication systems, bandwidth is a precious commodity, and service providers are continuously met with the challenge of accommodating more users with in a limited allocated bandwidth. To increase data rate of wireless medium with higher performance, OFDM (orthogonal frequency division multiplexing) is used. Recently DWT (Discrete wavelet transforms) is adopted in place of FFT (Fast Fourier transform) for frequency translation. Modulation schemes such as 16-QAM, 32-QAM, 64-QAM and 128-QAM (Quadrature amplitude modulation) have been used in the developed OFDM system for both DWT and FFT based model. In this paper we propose a DWT-IDWT based OFDM transmitter and receiver that achieve better performance in terms SNR and BER for AWGN channel. It proves all the wavelet families better over the IFFT-FFT implementation. The OFDM model is developed using Simulink, various test cases have been considered to verify its performance. The DWTOFDM using Lifting Scheme architecture is implemented on FPGA optimizing hardware, speed & cost. The wavelet filter used for this is Daubechies (9, 7) with N=2. The RTL code is written in Verilog-HDL and simulated in Modelsim. The design is then synthesized in Xilinx and implemented on Virtex5 FPGA board and the results were validated using ChipScope.
Performance analysis of DWT based OFDM over FFT based OFDM and implementing o...VLSICS Design
Growth in technology has led to unprecedented demand for high speed architectures for complex signal processing applications. In 4G wireless communication systems, bandwidth is a precious commodity, and service providers are continuously met with the challenge of accommodating more users with in a limited allocated bandwidth. To increase data rate of wireless medium with higher performance, OFDM (orthogonal frequency division multiplexing) is used. Recently DWT (Discrete wavelet transforms) is adopted in place of FFT (Fast Fourier transform) for frequency translation. Modulation schemes such as 16-QAM, 32-QAM, 64-QAM and 128-QAM (Quadrature amplitude modulation) have been used in the developed OFDM system for both DWT and FFT based model. In this paper we propose a DWT-IDWT based OFDM transmitter and receiver that achieve better performance in terms SNR and BER for AWGN channel. It proves all the wavelet families better over the IFFT-FFT implementation. The OFDM model is developed using Simulink, various test cases have been considered to verify its performance. The DWTOFDM using Lifting Scheme architecture is implemented on FPGA optimizing hardware, speed & cost. The wavelet filter used for this is Daubechies (9, 7) with N=2. The RTL code is written in Verilog-HDL and simulated in Modelsim. The design is then synthesized in Xilinx and implemented on Virtex5 FPGA board and the results were validated using ChipScope.
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Performance Evaluation of IEEE STD 802.16d Transceiver
1. IOSR Journal of Electronics and Communication Engineering (IOSR-JECE)
e-ISSN: 2278-2834,p- ISSN: 2278-8735.Volume 6, Issue 2 (May. - Jun. 2013), PP 21-26
www.iosrjournals.org
www.iosrjournals.org 21 | Page
Performance Evaluation of IEEE STD 802.16d Transceiver
Mrunal P. Pathak, S. A. Shirsat
Electronics and Telecommunication department, Student, ME (VLSI and Embedded System),
Sinhgad college of engineering, University Of Pune, Maharashtra, India.
Electronics and Telecommunication department, Assistant Professor,
Sinhgad college of engineering, University Of Pune, Maharashtra, India
Abstract : WiMAX ("Worldwide Interoperability for Microwave Access") technology is developed to meet the
growing demand of increased data rate and accessing the internet at high speeds. 802.16 family of standards is
officially called Wireless MAN in IEEE. Orthogonal frequency division multiplexing (OFDM) is multicarrier
modulation technique used in IEEE 802.16d (fixed WiMAX) communication standard. OFDM is used to
increase data rate of wireless medium with higher spectral efficiency. The proposed work is to evaluate
performance of IEEE Std 802.16d transceiver in MATLAB R2009b simulink environment. System performance
evaluated using BER vs SNR for different modulation technique such as 4 QAM, 16 QAM, 64 QAM under
different channel condition.
Keywords — 802.16d, MATLAB, OFDM, wimax.
I. Introduction
Wireless communication provide wireless connection and data transfer to connect with world anywhere
and anytime. Most of application demands high data rate with more coverage area. To achieve these
requirements IEEE introduced 802.16 standards. 802.16 family of standards is officially called WirelessMAN in
IEEE, it has been commercialized under the name “WiMAX”. It is used for wide coverage upto 40 Km with
data rates of 100 Mbps [1]. It is used for fixed broadband wireless access.
Modulation technique used in IEEE std 802.16d is OFDM (Orthogonal frequency division
multiplexing). OFDM is spectrally efficient modulation technique due to orthogonality principle. It is
computationally efficient due to the use of IFFT/FFT techniques to implement modulation/ demodulation
functions. In an OFDM scheme, a large number of orthogonal, overlapping, narrow band sub-channels or
subcarriers are transmitted in parallel. Advantages of OFDM are bandwidth efficiency, less intercarrier
interference (ICI) and less intersymbol interference (ISI).
Performance parameter of OFDM baseband transceiver IEEE std 802.16d is studied using simulation.
For simulation of system MATLAB R2009b is used. This OFDM system is able to support different M-QAM
modulation schemes.
This paper divides in 6 sections. Section 2 explains OFDM fundamentals. System block diagram is
described in section 3. Matlab based experimentation and results are presented in Section 4 and 5. Concluding
remarks are given in section 6.
Literature Review
Author [3] implements OFDM using System generator and Matlab & Simulink. The results presented show that
it is possible to implement an OFDM modulator for IEEE Std. 802.16 using Virtex II. These result shows that
configurable system can be implemented for different modulation technique. Implementation of the FEC
module, demodulator is future work for their project.
Author [4] describes a high level implementation of a high performance FFT for OFDM modulator and
demodulator of 802.16d. The design has been coded in Verilog and targeted into Xilinx Spartan3 field
programmable gate arrays. The design of the FFT is implemented and applied to fixed WiMAX—IEEE 802.16d
communication standard.
Author [6] presents FPGA implementation of the Reed- Solomon decoder for use in IEEE 802.16
WiMAX systems.The decoder is based on RS(255,239) code, and is additionally shortened and punctured
according to the WiMAX specifications. A Simulink model based on the System Generator library of low-level
Xilinx blocks was used for simulation and hardware implementation.
Author [7] presents the design and implementation of OFDM system. Author has tested system
performance by considering various design parameters using MATLAB 2011. All modules are designed using
VHDL programming language.
2. Performance Evaluation of IEEE STD 802.16d Transceiver
www.iosrjournals.org 22 | Page
II. Ofdm System
OFDM is a special case of multi-carrier modulation technique, where a single data stream is
transmitted over a number of lower rate sub-carriers. On classical frequency division multiplexing the total band
is divided into N non-overlapping frequency channels, while on OFDM the band is divided into a number of
overlapping frequency channels but with orthogonal frequencies. These orthogonal frequencies are obtained by
using the IFFT. An OFDM symbol is formed by the sum of N orthogonal frequency signals, and then to avoid
inter-symbol interference, a guard interval greater than the expected delay is added, during that time the signals
are replicated on a cyclic prefix to prevent the effect of selective frequency delay. At baseband, an OFDM signal
can be represented by a sum of modulated complex exponentials as (1).
S (t) = (1)
where Xk is a complex number representing a BPSK, QPSK, or 16 QAM baseband symbol modulating the
kth subcarrier and Δf is the subcarrier spacing. OFDM system is as shown in Fig 1.
Serial to
parallel
Paralle to
Serial
(sum)
High bit
rate R
Freq 1
Freq 2
Freq N
Low bit
rate R/N
Fig 1 Multicarrier FDM or OFDM [8]
III. System block diagram
Physical layer of IEEE 802.16d transmitter and receiver diagram is as shown in Fig. 2.
(a)
(b)
Fig 2 a 802.16d transmitter block diagram for the OFDM PHY [1]
b 802.16d receiver block diagram for the OFDM PHY [1]
3.1 Transmitter
The main components of OFDM transmitter are shown in Fig. 2a. The scrambler also known as
randomizer is used as random bit generator. The first three blocks are used for data coding and interleaving. The
coded bits will be mapped by the constellation modulator. The OFDM consist of serial to parallel converter
which converts the data bits from the serial form to the parallel form. The Inverse Fast Fourier Transform
(IFFT) transforms the signals from the frequency domain to the time domain, an IFFT converts a number of
complex data points, of length that is power of 2, into the same number of points but in the time domain. The
number of subcarriers determines how many sub-bands the available spectrum is split into. The Cyclic Prefix
(CP) is a copy of the last N samples from the IFFT, which are placed at the beginning of the OFDM frame to
overcome ISI problem. It is important to choose the minimum necessary CP to maximize the bandwidth
efficiency of the system.
IFFT
Output
3. Performance Evaluation of IEEE STD 802.16d Transceiver
www.iosrjournals.org 23 | Page
3.2 Receiver
The main blocks of OFDM receiver are as shown in Fig. 2b. The received signal goes through the
cyclic prefix removal and a serial-to-parallel converter. After that, the signals are passed through an N-point fast
Fourier transform to convert the signal to frequency domain. The output of the FFT is formed from the first M
samples of the output. The reverse of forward error correction block obtained by convolutional decoder, RS
decoder and de-scrambler. The recovered signal get same as transmitted by transmit signal.
3.3 Modulation
OFDM physical layer is adaptive and supports different modulation techniques. Table 1 summarized
channel coding parameters for various modulation techniques.
TABLE 1
Channel coding per modulation technique for 802.16d [1]
Modulation Uncoded
block size
(bytes)
Coded
block
size
(bytes)
Overal
l rate
RS- code CC code
Rate
BPSK 12 24 1/2 (12,12,0) 1/2
4 QAM 24 48 1/2 (32,24,4) 2/3
4 QAM 36 48 3/4 (40,36,2) 5/6
16-QAM 48 96 1/2 (64,48,8) 2/3
16-QAM 72 96 3/4 (80,72,4) 5/6
64-QAM 96 144 2/3 (108,96,6) 3/4
64-QAM 108 144 3/4 (120,108,6) 5/6
3.4 Physical Layer Specification for OFDM of 802.16d.
Table 2 shows the physical layer specifications of 802.16d for OFDM module.
TABLE 2
Physical layer Specification [1]
IFFT length Nfft 256
Bandwidth B 10 MHz
No of subcarrier Nc 256
Subcarrier spacing F=B/Nc 39.06KHz
Useful symbol time Tfft/Tb =1/F 25.6usec
Sampling time Ts=Tofdm/Nfft 0.1 usec
Guard interval 64 * Ts 6.4 usec
Signal duration Tsignal= Tb+Tg 32 usec
IV. Transceiver Model Of IEEE STD 802.16d
Fig 3 shows transceiver model of IEEE STD 802.16d simulated using MATLAB and SIMULINK.
Fig 3 Simulink diagram of 802.16d OFDM PHY layer for 4 QAM modulation.
The simulation parameters used are:
4. Performance Evaluation of IEEE STD 802.16d Transceiver
www.iosrjournals.org 24 | Page
Number of subcarriers: 256 (for FFT)
Modulation Scheme: 4 QAM, 16 QAM and 64 QAM
Channel: AWGN
As shown in Fig. 3 Bernoulli binary this data source acts as information signal is fed to the baseband
transmitter. As specified in the standard, 802.16d OFDM PHY layer baseband transmitter is composed of three
major parts: channel coding, modulation, and OFDM transmitter. For the receiver complementary operations are
applied in the reverse order. The structure of IEEE 802.16d OFDM PHY layer is shown in Fig. 3. The first
block in the transmitter is randomizer. The timing recovery problem at the receiver is minimized by use of
randomizer which prevent a long sequence of 1s and 0s. In 802.16d standard the randomizer is implemented
with a 15 bits shift register and XOR gates. Error detection and correction is carried out by forward error
correction block which is composed of Reed-Solomon encoder, convolutional encoder and puncture (used to
adjust different data rate). These are the mandatory blocks on the standard FEC, consisting of the concatenation
of a Reed-solomon outer code and a rate-compatible convolutional inner code. The modulation used in 802.16d
is integer-mapped 4 QAM, 16 QAM, 64 QAM.
OFDM transmitter is composed of three parts: assemble OFDM frame, create OFDM signal by performing
IFFT/FFT, and cyclic prefix. Data is sent in the form of OFDM symbols. Accurate synchronization is necessary
to ensure correct baseband processing. OFDM systems are very sensitive to frequency offset because there
might be loss of orthogonality between sub symbols. Accurate synchronization is necessary to ensure correct
baseband processing. OFDM systems are very sensitive to frequency offset because there might be loss
orthogonality between sub symbol.
V. Simulation Results
Systematic computer simulations were carried out to evaluate the Bit Error Rate (BER) performance of
IEEE 802.16d.Bit error rate is the rate at which errors occur in a transmission system. In mathematical form it
idefined as:BER = number of errors / total number of bits sent.The calculation gives, how system performs?The
platformemployed for performing the simulations is MATLAB vR2009b.
Fig 4 OFDM with 4-QAM scatter plot for modulator/demodulator SNR=20 dB
Fig. 4 shows the scatter plot of transmitted and received data. Received scatter plot consist of noise in signal
of AWGN at SNR= 20dB. Fig. 5 shows 15 bit transmitted and received data which shows receiver get
transmitted data.
5. Performance Evaluation of IEEE STD 802.16d Transceiver
www.iosrjournals.org 25 | Page
Fig 5 Transmitted and recovered signal.
Fig. 6 show a comparison of the simulation results for 4-QAM, 16-QAM and 64-QAM for AWGN channel.
Simulation results shows that 4 QAM has good BER vs Eb/No performance than 16 QAM and 64 QAM. 64
QAM is spectrally efficient as it transfer 8 bps/Hz where as 4 QAM 2bps/Hz. This shows there is trade off
between spectral efficiency and BER vs Eb/No.
Fig 6 BER for received signal for AWGN channel
Fig. 7 shows the performance of system for different modulation techniques with Rayleigh fading channel
effect. 4 QAM has less BER rate for higher Eb/No. 4 QAM is better BER rate than 16 QAM and 64 QAM for
higher value of Eb/No.
Fig 7 BER for received signal for Rayleigh channel
6. Performance Evaluation of IEEE STD 802.16d Transceiver
www.iosrjournals.org 26 | Page
Fig. 8 shows comparison between AWGN and Rayleigh channel. The performance for AWGN channel is
best than Rayleigh channel as it has the lower BER under 4 QAM. It is same for 16-QAM and 64-QAM
modulation techniques.
Fig 8 BER performance of AWGN and Raleigh Channels for 4-QAM and 64-QAM modulation techniques.
VI. Conclusion
The performance of an OFDM based WiMAX communication system with different digital modulation
techniques and channel is studied. Receiver gets same data as transmitted from transmitter. 4 QAM modulation
techniques has good BER vs Eb/No performance for both AWGN and Rayleigh channel.
BER performance for AWGN channel is better than Rayleigh channel. WiMax Transceiver simulated
in MATLAB shows better performance for AWGN channel than fading channel (Rayleigh channel). The next
objective of this work is to design and implement baseband OFDM transceiver on FPGA hardware.
Acknowledgement
I am glad to express my sincere thanks to Prof. S. A. Shirsat who offered me valuable and constructive
tips for my work.
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[3] Joaquin Garcia, Rene Cumplido Department of Computer Science , “On the design of an FPGA-Based OFDM modulator for IEEE
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[6] Miljko Bobrek, Kenyon H. Clark, Austin P. Albright “FPGA Implementation of Reed-Solomon Decoder for IEEE 802.16 WiMAX
Systems using Simulink-Sysgen Design Environment” Oak Ridge National Laboratory Cognitive Radio Program 1 Bethel Valley
Rd Oak Ridge ,TN 37831.
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