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HiperLAN2[3].The orthogonality of the subcarriers is no longer
maintained which results in ICI (Inter carrier Interference)[4]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 Due to this the orthogonality of the subcarriers is no
longer maintained which results in ICI (Inter carrier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.
In Frequency-division multiple access (FDMA), the available channel bandwidth is divided into many non overlapping frequency bands, where each band is dynamically assigned to a specific user to transmit data.
Like FDM, OFDM uses multiple subcarriers BUT:
There are closely spaces to each other without causing interference, removing guard bands.
Its possible because subcarriers are orthogonal.
OFDMA allocates multi-user in time domain as well in frequency domain. OFDMA is a very popular Multiplexing method used for many of the latest wireless and telecommunication standards,
orthogonal frequency division multiplexing(OFDM)
its orthogonal frequency multiplexing topic basicallly in digital signal processing , network signal and system , it also helpful in engineering course either electrical or electronics and communication engineering.
In Frequency-division multiple access (FDMA), the available channel bandwidth is divided into many non overlapping frequency bands, where each band is dynamically assigned to a specific user to transmit data.
Like FDM, OFDM uses multiple subcarriers BUT:
There are closely spaces to each other without causing interference, removing guard bands.
Its possible because subcarriers are orthogonal.
OFDMA allocates multi-user in time domain as well in frequency domain. OFDMA is a very popular Multiplexing method used for many of the latest wireless and telecommunication standards,
orthogonal frequency division multiplexing(OFDM)
its orthogonal frequency multiplexing topic basicallly in digital signal processing , network signal and system , it also helpful in engineering course either electrical or electronics and communication engineering.
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.
OFDM allows tightly packed carriers to convey information orthogonally and with high bandwidth efficiency
Objectives Description:
Concepts
Basic idea
Introduction to OFDM
Implementation
Advantages and Drawbacks.
FDMA
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
Wireless Communication and Networking by WilliamStallings Chap2Senthil Kanth
Hai I'm Senthilkanth, doing MCA in Mepco Schlenk Engineering College..
The following presentation covers topic called Wireless Communication and Networking
by WilliamStallings for BSc CS, BCA, MSc CS, MCA, ME students.Make use of it.
Wireless Communication and Networking
by WilliamStallings Chapter : 2Transmission Fundamentals
Chapter 2
Electromagnetic Signal
Function of time
Can also be expressed as a function of frequency
Signal consists of components of different frequencies
Time-Domain Concepts
Analog signal - signal intensity varies in a smooth fashion over time
No breaks or discontinuities in the signal
Digital signal - signal intensity maintains a constant level for some period of time and then changes to another constant level
Periodic signal - analog or digital signal pattern that repeats over time
s(t +T ) = s(t ) -¥< t < +¥
where T is the period of the signal
Time-Domain Concepts
Aperiodic signal - analog or digital signal pattern that doesn't repeat over time
Peak amplitude (A) - maximum value or strength of the signal over time; typically measured in volts
Frequency (f )
Rate, in cycles per second, or Hertz (Hz) at which the signal repeats
Time-Domain Concepts
Period (T ) - amount of time it takes for one repetition of the signal
T = 1/f
Phase () - measure of the relative position in time within a single period of a signal
Wavelength () - distance occupied by a single cycle of the signal
Or, the distance between two points of corresponding phase of two consecutive cycles
Sine Wave Parameters
General sine wave
s(t ) = A sin(2ft + )
Figure 2.3 shows the effect of varying each of the three parameters
(a) A = 1, f = 1 Hz, = 0; thus T = 1s
(b) Reduced peak amplitude; A=0.5
(c) Increased frequency; f = 2, thus T = ½
(d) Phase shift; = /4 radians (45 degrees)
note: 2 radians = 360° = 1 period
Sine Wave Parameters
Time vs. Distance
When the horizontal axis is time, as in Figure 2.3, graphs display the value of a signal at a given point in space as a function of time
With the horizontal axis in space, graphs display the value of a signal at a given point in time as a function of distance
At a particular instant of time, the intensity of the signal varies as a function of distance from the source
Frequency-Domain Concepts
Fundamental frequency - when all frequency components of a signal are integer multiples of one frequency, it’s referred to as the fundamental frequency
Spectrum - range of frequencies that a signal contains
Absolute bandwidth - width of the spectrum of a signal
Effective bandwidth (or just bandwidth) - narrow band of frequencies that most of the signal’s energy is contained in
Frequency-Domain Concepts
Any electromagnetic signal can be shown to consist of a collection of periodic analog signals (sine waves) at different amplitudes, frequencies, and phases
The period of the total signal is equal to the period of the fundamenta
This research study was carried out to see the effect of
atherosclerotic changes inside femoral arteries with the help of
diagnostic Ultrasound. Atherosclerosis in femoral arteries is
meant by any kind of damage to internal thin cell lining of
arterial walls of femoral arteries called as endothelium, which
may be due to consistent or rapid increase in blood pressure or
high level of fat deposition. To see the effect of atherosclerotic
changes in the femoral arteries of some cases, the method of
finding a change along x-axis and y-axis in the structure of
triphasic type of ultrasound image waveform was used. The
change was found to be like the production of biphasic type of
ultrasound image with prolonged portion of diastole and small
peak of systole. In case of monophasic type only low peak systole
occurred with no portion of diastole. Five cases were taken for
study. All these cases had a history of high blood pressure and
use of unbalanced diet in their normal routine. It was concluded
that formation of prolonged diastole along x-axis with low peak
of systole along y-axis in biphasic type of ultrasound image, and
formation of low peak systole along y-axis without any
component along x-axis in monophasic type of ultrasound image,
both are good indicator of atherosclerotic changes in the femoral
arteries.
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.
OFDM allows tightly packed carriers to convey information orthogonally and with high bandwidth efficiency
Objectives Description:
Concepts
Basic idea
Introduction to OFDM
Implementation
Advantages and Drawbacks.
FDMA
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
Wireless Communication and Networking by WilliamStallings Chap2Senthil Kanth
Hai I'm Senthilkanth, doing MCA in Mepco Schlenk Engineering College..
The following presentation covers topic called Wireless Communication and Networking
by WilliamStallings for BSc CS, BCA, MSc CS, MCA, ME students.Make use of it.
Wireless Communication and Networking
by WilliamStallings Chapter : 2Transmission Fundamentals
Chapter 2
Electromagnetic Signal
Function of time
Can also be expressed as a function of frequency
Signal consists of components of different frequencies
Time-Domain Concepts
Analog signal - signal intensity varies in a smooth fashion over time
No breaks or discontinuities in the signal
Digital signal - signal intensity maintains a constant level for some period of time and then changes to another constant level
Periodic signal - analog or digital signal pattern that repeats over time
s(t +T ) = s(t ) -¥< t < +¥
where T is the period of the signal
Time-Domain Concepts
Aperiodic signal - analog or digital signal pattern that doesn't repeat over time
Peak amplitude (A) - maximum value or strength of the signal over time; typically measured in volts
Frequency (f )
Rate, in cycles per second, or Hertz (Hz) at which the signal repeats
Time-Domain Concepts
Period (T ) - amount of time it takes for one repetition of the signal
T = 1/f
Phase () - measure of the relative position in time within a single period of a signal
Wavelength () - distance occupied by a single cycle of the signal
Or, the distance between two points of corresponding phase of two consecutive cycles
Sine Wave Parameters
General sine wave
s(t ) = A sin(2ft + )
Figure 2.3 shows the effect of varying each of the three parameters
(a) A = 1, f = 1 Hz, = 0; thus T = 1s
(b) Reduced peak amplitude; A=0.5
(c) Increased frequency; f = 2, thus T = ½
(d) Phase shift; = /4 radians (45 degrees)
note: 2 radians = 360° = 1 period
Sine Wave Parameters
Time vs. Distance
When the horizontal axis is time, as in Figure 2.3, graphs display the value of a signal at a given point in space as a function of time
With the horizontal axis in space, graphs display the value of a signal at a given point in time as a function of distance
At a particular instant of time, the intensity of the signal varies as a function of distance from the source
Frequency-Domain Concepts
Fundamental frequency - when all frequency components of a signal are integer multiples of one frequency, it’s referred to as the fundamental frequency
Spectrum - range of frequencies that a signal contains
Absolute bandwidth - width of the spectrum of a signal
Effective bandwidth (or just bandwidth) - narrow band of frequencies that most of the signal’s energy is contained in
Frequency-Domain Concepts
Any electromagnetic signal can be shown to consist of a collection of periodic analog signals (sine waves) at different amplitudes, frequencies, and phases
The period of the total signal is equal to the period of the fundamenta
This research study was carried out to see the effect of
atherosclerotic changes inside femoral arteries with the help of
diagnostic Ultrasound. Atherosclerosis in femoral arteries is
meant by any kind of damage to internal thin cell lining of
arterial walls of femoral arteries called as endothelium, which
may be due to consistent or rapid increase in blood pressure or
high level of fat deposition. To see the effect of atherosclerotic
changes in the femoral arteries of some cases, the method of
finding a change along x-axis and y-axis in the structure of
triphasic type of ultrasound image waveform was used. The
change was found to be like the production of biphasic type of
ultrasound image with prolonged portion of diastole and small
peak of systole. In case of monophasic type only low peak systole
occurred with no portion of diastole. Five cases were taken for
study. All these cases had a history of high blood pressure and
use of unbalanced diet in their normal routine. It was concluded
that formation of prolonged diastole along x-axis with low peak
of systole along y-axis in biphasic type of ultrasound image, and
formation of low peak systole along y-axis without any
component along x-axis in monophasic type of ultrasound image,
both are good indicator of atherosclerotic changes in the femoral
arteries.
Multiagent Based Methodologies have become an
important subject of research in advance Software Engineering.
Several methodologies have been proposed as, a theoretical
approach, to facilitate and support the development of complex
distributed systems. An important question when facing the
construction of Agent Applications is deciding which
methodology to follow. Trying to answer this question, a
framework with several criteria is applied in this paper for the
comparative analysis of existing multiagent system
methodologies. The results of the comparative over two of them,
conclude that those methodologies have not reached a sufficient
maturity level to be used by the software industry. The
framework has also proved its utility for the evaluation of any
kind of Multiagent Based Software Engineering Methodology
Baylis-Hillman reaction has been achieved on
different organic motifs but with completion times of three to
six days. Micellar medium of CTAB in water along with the
organic base DABCO has been used to effect the BaylisHillman
reaction on a steroidal nucleus of Withaferin-A for the
first time with different aromatic aldehydes within a day to
synthesize a library of BH adducts (W1a –W14a) and (W1bW14b)
as a mixture of two isomers and W15 as a single
compound. The isomers were separated on column and the
major components were chosen for bio-evaluation. Cytotoxic
activity of the synthesized compounds was screened against a
panel of four cancer cell lines Lung A-549, Breast MCF-7,
Colon HCT-116 and Leukemia THP-1 along with 5-florouracil
and Mitomycin-C as references. All the compounds exhibited
promising activity against screened cell lines and were found to
possess enhaunced activity than parent compound. BH adducts
with aromatic systems having methoxy and nitro groups were
found to be more active.
Background and objectives: Iron is one of the major component
of hemoglobin, is required for transport of oxygen, ferritin is a
protein for storage iron, and transferring is a protein for iron
transport, all these it may be change in breast cancer.
The aim of present study was to measure the serum ferritin, iron,
total iron binding capacity, transferring, and C-reactive protein
concentration in breast tumors.
Material and method: A prospective study was carried out from
April 2013 to August 2014 by clinical biochemistry department in
College of Pharmacy-University of Sulaimani on (45) healthy
female individuals, (group 1) and (50) females with breast tumor
(group 2).
Results: The mean value of serum iron, transferring, total iron
binding capacity were significantly lower in females with breast
tumors (group 2), than that of healthy female individuals, (group
1), while serum ferritin was significantly higher in females with
breast tumors (group2), than that of healthy individuals (group
1).
Conclusion: Based on findings of the present study it can be
concluded that breast tumors can cause deficient of all iron
profile except ferritin will be increase in female breast cancers.
Key words- Serum iron, S.Ferritin, S. Total iron binding, S.
Transferrin, S.C-Reactive protein, breast tumors.
Мы организовываем 5 недель активностей, которые взорвут вашу группу! Что сделать, чтобы полюбиться участникам? Как создать элиту группы? Как заполучить доверие и лояльность? Об этом в нашей презентации!
The importance of employee satisfaction and work motivation is growing all the time in the companies. Many researchers have been made to find out the effect the job satisfaction and motivation have in the productivity of the company. This paper is about the employee satisfaction in a Pharmaceutical company in India. This paper wanted to find out in practice what the level of employee satisfaction in a company is. After the target organization had been found, the research question will composed: what is the level of employee satisfaction in. The main subjects will be leadership and motivation, and the affect they have on employee satisfaction. To find out the results for the research, questionnaires will be delivering to the employees, in the company. The purpose of this kind of research is to find out which factors could be improved in the target company and how to make employees enjoy their work every day.
Keywords- employee satisfaction, work motivation, leadership, Expectation, Wages.
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.
Performance Analysis of OFDM in Combating Multipath FadingIOSR Journals
Mobile Communication system has been on high rampage for high data transmission over wireless
medium with various challenges caused by the transmission Channel. OFDM is been discovered in recent years
to deal with this problems because of its ability to elegantly cope with multipath interference. This paper
investigates the performance of different modulation schemes using M-ary Phase Shift Keying (M-PSK) and Mary
Quadrature Amplitude Modulation (M-QAM) in information transmission with OFDM technique over Ideal
channel AWGN and worst channel Rayleigh Fading channel in terms of Bits Error Rate (BER). Analysis was
made for different types of modulation schemes BPSK, QPSK, 4-QAM and 16-QAM gray coded bit mapping.
Also, a feasibility of OFDM been used to combat multipath fading was analyzed with comparison between a
single carrier technique and OFDM multicarrier technique. Variation between SNR results with respect to BER
is plotted to show the trade off differences between the modulation schemes with the result showing that OFDM
allows data transmission with minimal error over fading channel than a Single Carrier
Performance Analysis of OFDM in Combating Multipath FadingIOSR Journals
Abstract: Mobile Communication system has been on high rampage for high data transmission over wireless medium with various challenges caused by the transmission Channel. OFDM is been discovered in recent years to deal with this problems because of its ability to elegantly cope with multipath interference. This paper investigates the performance of different modulation schemes using M-ary Phase Shift Keying (M-PSK) and M-ary Quadrature Amplitude Modulation (M-QAM) in information transmission with OFDM technique over Ideal channel AWGN and worst channel Rayleigh Fading channel in terms of Bits Error Rate (BER). Analysis was made for different types of modulation schemes BPSK, QPSK, 4-QAM and 16-QAM gray coded bit mapping. Also, a feasibility of OFDM been used to combat multipath fading was analyzed with comparison between a single carrier technique and OFDM multicarrier technique. Variation between SNR results with respect to BER is plotted to show the trade off differences between the modulation schemes with the result showing that OFDM allows data transmission with minimal error over fading channel than a Single Carrier. Keywords: OFDM, Single Carrier, AWGN, Rayleigh fading, BER, M-ary PSK, M-ary QAM
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.
An Adaptive Approach to Switching Coded Modulation in OFDM System Under AWGN ...ijsrd.com
In this paper we have studied the OFDM for different Quadrature amplitude modulation technique (QAM) The scatter plot and their output signal to noise ratio, dependent bit error rate variation is analyzed for every type of modulation in OFDM. After observing the BER for each SNR in the system, switching threshold range has been prepared and now system is ready to face the Adaptive coded modulation (ACM).The results shows the switching of modulation technique.
Abstract: The growing demand on wireless communication service has created the necessity to support higher data rates for multimedia services. .As next generation wireless communication networks are expected to provide broadband multimedia services such as voice, web browsing, video conferencing etc. For high data rate achievement one must enhance the capacity of the wireless communication system. The capacity of a communication system can be enhanced by using OFDM system. OFDM is commonly used for communication system due to its high transmission rate and robustness against multipath fading So as to enhance the capacity of fading channels the OFDM system are combined to form hybrid system. Capacity is the measure of maximum information that can be transmitted reliably over a channel. This paper review on different channel capacity enhancement techniques used in OFDM system is SVD (Singular Value Decomposition), water Filling algorithm.
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.
Blind Channel Shortening for MIMO-OFDM System Using Zero Padding and Eigen De...ijsrd.com
This paper deals with multiple-input multiple-output (MIMO) broadband wireless communication systems, employing orthogonal frequency-division multiplexing (OFDM). In order to exploit the benefits of OFDM in highly frequency-selective channels, without any significant increase in receiver complexity, a channel shortening prefilter is inserted at the receiver. The main aim of inserting channel shorteners is to shorten the channel so that the main energy of the composite channel is concentrated within a duration smaller than the guard interval inserted while transmission. Thus by including channel shortening equalizers at the receiver the inter symbol interference or the inter block interference can be suppressed. The new approach proposed in this thesis is zero padding approach with Eigen decomposition approach. The advantages of the proposed approaches include immunity to delay spread, resistance to frequency selective fading and simple equalization. This shortening design is a blind one, i.e., a priori knowledge of the MIMO channel impulse response to be shortened is not required, and can be carried out in closed-form.
Peak to Average Ratio PAPR Reduction Technique in OFDM MIMO System A Reviewijtsrd
Orthogonal Frequency Division Multiplexing OFDM is an new method for fourth generation wireless communication. MIMO OFDM has become a promising candidate for high performance 4G and 5G broadband wireless communications. However, one main of MIMO OFDM is the high peak to average power ratio PAPR of the transmitter’s output signal on different antennas. In this paper, we present a new noble SLM PAPR reduction techniques such as selective mapping technique and Partial transmit sequence techniques and shows which of these PAPR reduction techniques are more effective to reduce PAPR in OFDM MIMO. Er. Sukhjinder Singh | Dr. Hitanshu Kumar | Dr. Arashdeep Singh "Peak to Average Ratio (PAPR) Reduction Technique in OFDM-MIMO System- A Review" Published in International Journal of Trend in Scientific Research and Development (ijtsrd), ISSN: 2456-6470, Volume-6 | Issue-3 , April 2022, URL: https://www.ijtsrd.com/papers/ijtsrd49719.pdf Paper URL: https://www.ijtsrd.com/engineering/electronics-and-communication-engineering/49719/peak-to-average-ratio-papr-reduction-technique-in-ofdmmimo-system-a-review/er-sukhjinder-singh
Similar to DESIGN AND IMPLEMENTATION OF OFDM SYSTEM AND REDUCTION OF INTER-CARRIER INTERFERENCE (20)
Recent joint surgery studies reveal increased
revisions and resurfacing of the metal on metal hip joints. Metal
on metal hip implants were developed more than thirty years ago
and their application has been refined because of availability of
advanced manufacturing techniques and partly by advancements
in material science and engineering. Development of composite
materials may provide greater durability to metal-on-metal hip
implants .This review article is a study of the latest literature of
metal-on-metal hip implants and its various modeling techniques.
Numbers of methods are used for convergence and numerical
solution to investigate the performance of metal-on-metal hip
implant for accurate stable solution. This paper presents analysis
done by various researchers on metal-on-metal hip implants for
wear, lubrication, fatigue, bio-tribo-corrosion, design, toxicity
and resurfacing. After in vivo and in vitro studies, it is found that
all these methods have limitations. There is a need of more
insight for lubrication analysis, geometry of bearings, materials
and input parameters. The information provided in this work is
intended as an aid in the assessment of metal-on-metal hip joints.
Background Hospital contributes significantly tangible and intangible resources on a concurred plan by the scheduling of surgery on the OT list. Postponement decreases efficiency by declining throughput leads to wastage of resources hence burden to the nation. Patients and their family face economic and emotional implication due to the postponement. Postponement rate being a quality indicator controls check mechanism could be developed from the results. Postponement of elective scheduled operations results in inefficient use of the operating room (OR) time on the day of surgery. Inconvenience to patients and families are also caused by postponements. Moreover, the day of surgery (DOS) postponement creates logistic and financial burden associated with extended hospital stay and repetitions of pre-operative preparations to an extent of repetition of investigations in some cases causing escalated costs, wastage of time and reduced income. Methodology A cross-sectional study was done in the operation theaters of a tertiary care hospital in which total ten operation theaters of General Surgery Data of scheduled, performed and postponed surgeries was collected from all the operation theater with effect from March 1st to September 30th, 2018. A questionnaire was developed to find out the reasons for the postponement for all hospital’s stakeholders (surgeons, Anesthetist, Nursing Officer) and they were further evaluated time series analysis of scheduling of Operation Theater for moving average technique. Results Total 958 surgeries were scheduled and 772 surgeries performed were and 186 surgeries were postponed with a postponement rate of 19.42% in the cardiac surgery department during the study period. Month-wise postponement Rate exponential smoothing of time series data shows the dynamic of operating suits. To test throughput Postponement rate was plotted the postponed surgeries and on regression analysis is in a perfect linear relationship.
Introduction: Postponement of elective scheduled operations results in inefficient use of operating room (OR) time on the day of surgery. Inconvenience to patients and families also caused by postponements. Moreover, day of surgery (DOS) postponement creates logistic and financial burden associated with extended hospital stay and repetitions of pre-operative preparations to an extend of repetition of investigations in some cases causing escalated costs, wastage of time and reduced income. Methodology: A cross sectional study was done in the operation theaters of a tertiary care hospital in which total ten operation theaters of General Surgery Data of scheduled, performed and postponed surgeries was collected from all the operation theater with effect from march 1st to September 30th 2018. A questionnaire was developed to find out the reasons for the postponement for all hospital’s stakeholders (Surgeons, Anesthetist, Nursing officer) and they were further evaluated Time series analysis of scheduling of Operation Theater for Moving average Technique. Results: total 2,466 surgeries were scheduled and 1,980 surgeries were performed and 486 surgeries were postponed in the general surgery department during the study period. Month wise postponement forecast was in accordance with the performed surgeries and on regression analysis postponed surgeries were in perfect linear relationship with the postponement Rate.
In the present paper the experimental study of
Nanotechnology involves high cost for Lab set-up and the
experimentation processes were also slow. Attempt has also
been made to discuss the contributions towards the societal
change in the present convergence of Nano-systems and
information technologies. one cannot rely on experimental
nanotechnology alone. As such, the Computer- simulations and
modeling are one of the foundations of computational
nanotechnology. The computer modeling and simulations
were also referred as computational experimentations. The
accuracy of such Computational nano-technology based
experiment generally depends on the accuracy of the following
things: Intermolecular interaction, Numerical models and
Simulation schemes used. The essence of nanotechnology is
therefore size and control because of the diversity of
applications the plural term nanotechnology is preferred by
some nevertheless they all share the common feature of control
at the nanometer scale the latter focusing on the observation
and study of phenomena at the nanometer scale. In this paper,
a brief study of Computer-Simulation techniques as well as
some Experimental result
Solar cell absorber Kesterite- type Cu2ZnSnS4 (CZTS) thin films have been prepared by Chemical Bath Deposition (CBD). UV–vis absorption spectra measurement indicated that the band gap of as-synthesized CZTS was about1.68 eV, which was near the optimum value for photovoltaic solar conversion in a single-band-gap device. The polycrystalline CZTS thin films with kieserite crystal structure have been obtained by XRD. The average of crystalline size of CZTS is 27 nm
Multilevel inverters play a crucial part in the
areas of high and medium voltage applications. Among the three
main multilevel inverters used, the capacitor clamped multilevel
inverter(CCMLI) has advantage with respect to voltage
redundancies. This work proposes a switching pattern to improve
the performance of chosen H-bridge type CCMLI over
conventional CCMLI. The PWM technique used in this work is
Phase Opposition Disposition PWM(PODPWM). The
performance of proposed H-bridge type CCMLI is verified
through MATLAB-Simulink based simulation. It has been
observed that the THD is low in chosen CCMLI compared to
conventional CCMLI.
- In this paper, we introduce a practical mechanism of
compressing a binary phase code modulation (BPCM) signal
according to Barker code with 13 chips in presence of additive
white Gaussian noise (AWGN) by using a digital matched filter
(DMF) corresponding to time domain convolution algorithm of
input and reference signals using Cyclone II EP2C70F896C6
FPGA from ALTERA placed on education and development
board DE2-70 with the following parameters: frequency of
BPCM signal fIF=2 MHz, sampling frequency
f MHz SAM 50
,pulse period
T 200s
, pulse width
S 13sc
, chip width
CH 1sc
, compressing factor
KCOM 13
, SNRinp=1/1, 1/2, 1/3, 1/4, 1/5 and processing
gain factor SNRout/SNRinp=11.14 dB.
The results of filter operation are evaluated using a digital
oscilloscope GDS-1052U to display the input and output signals
for different SNRinp.
Flooding is one of the most devastating natural
disasters in Nigeria. The impact of flooding on human activities
cannot be overemphasized. It can threaten human lives, their
property, environment and the economy. Different techniques
exist to manage and analyze the impact of flooding. Some of these
techniques have not been effective in management of flood
disaster. Remote sensing technique presents itself as an effective
and efficient means of managing flood disaster. In this study,
SPOT-10 image was used to perform land cover/ land use
classification of the study area. Advanced Space borne Thermal
Emission and Reflection Radiometer (ASTER) image of 2010 was
used to generate the Digital Elevation Model (DEM). The image
focal statistics were generated using the Spatial Analyst/
Neighborhood/Focal Statistics Tool in ArcMap. The contour map
was produced using the Spatial Analyst/ Surface/ Contour Tools.
The DEM generated from the focal statistics was reclassified into
different risk levels based on variation of elevation values. The
depression in the DEM was filled and used to create the flow
direction map. The flow accumulation map was produced using
the flow direction data as input image. The stream network and
watershed were equally generated and the stream vectorized. The
reclassified DEM, stream network and vectorized land cover
classes were integrated and used to analyze the impact of flood on
the classes. The result shows that 27.86% of the area studied will
be affected at very high risk flood level, 35.63% at high risk,
17.90% at moderate risk, 10.72% at low risk, and 7.89% at no
risk flood level. Built up area class will be mostly affected at very
high risk flood level while farmland will be affected at high risk
flood level. Oshoro, Imhekpeme, and Weppa communities will be
affected at very high risk flood inundation while Ivighe, Uneme,
Igoide and Iviari communities will be at risk at high risk flood
inundation level. It is recommended among others that buildings
that fall within the “Very High Risk” area should be identified
and occupants possibly relocated to other areas such as the “No
Risk” area.
Without water, humans cannot live. Since time began,
we have lived by the water and vast tracts of waterless land have
been abandoned as it is too difficult to inhabit. At any given
moment, the earth’s atmosphere contains 4,000 cubic miles of
water, which is just 0.000012% of the 344 million cubic miles of
water on earth. Nature maintains this ratio via evaporation and
condensation, irrespective of the activities of man.
There is a certain need for an alternative to solve the water
scarcity. Obtaining water from the atmosphere is nothing new -
since the beginning of time, nature’s continuous hydrologic cycle
of evaporation and condensation in the form of rain or snow has
been the sole source and means of regenerating wholesome water
for all forms of life on earth.
An effective method to generate water is by the separation of
moisture present in air by condensation. In this study, the water
present in air is condensed on the surface of a container and then
collected in an external jacket provided on the container.
Insulations are provided to optimize the inner temperature of the
container.
The method is although uncommon but has certain advantages
which make it a success. The process is economical and does not
require a lot of utilities. It also helps in further reducing the
carbon footprint.
In every moment of functioning the Li-Ion
battery must provide the power required by the user, to have a
long operating life and to and to provide high reliability in
operation. The methods for analysis and testing batteries are
ensuring that all these conditions imposed to the batteries are
met by being tested depending on their intended use.
The success rate of real estate project is
decreasing as there is large scale of project and participation of
entities. It is necessary to study the risk factors involved in the
project. This paper focused on types of risks involved in the
project, risk factors, risk management tools & techniques.
Identification of risk of the project in terms of the total cost of the
project has been divided under Technical, Financial, Sociopolitical
and Statutory cost centers. Large real estate projects
have to tackle the following issues: land acquisition, skilledlabour
shortage, non-availability of skilled project managers, and
mechanization of the construction process to cater to the growing
demands. Non- availability of supporting infrastructure, political
issues like instability of the government leading to regulatory
issues, social issues, marketing forms an important part in these
projects as this is a onetime investment and the purchase cycle is
long , long development period makes the same project be at
different points in the real estate value cycle.
- In the present scenario carbon emission and sand
mining are major concern due to its hazardous effect to
environment and making serious imbalance to the ecosystem.
Various studies have been conducted to reduce severe effect on
environment, using byproducts like copper slag as partial
replacement of fine aggregate. Different researchers have also
revealed numerous uses of copper slag as a replacing agent in
determining the strength of concrete. A comprehensive review of
studies has been presented in this paper for scope of replacement
of fine aggregate from copper slag in concrete
- Security is a concept similar to being cautious
or alert against any danger. Network security is the condition of
being protected against any danger or loss. Thus safety plays a
important role in bank transactions where disclosure of any data
results in big loss. We can define networking as the combination
of two or more computers for the purpose of resource sharing.
Resources here include files, database, emails etc. It is the
protection of these resources from unauthorized users that
brought the development of network security. It is a measure
incorporated to protect data during their transmission and also
to ensure the transmitted is protected and authentic.
Security of online bank transactions here has been
improved by increasing the number of bits while establishing the
SSL connection as well as in RSA asymmetric key encryption
along with SHA1 used for digital signature to authenticate the
user
Background: Septoplasty is a common surgical
procedure performed by otolaryngologists for the correction of
deviated nasal septum. This surgery may be associated with
numerous complications. To minimize these complications,
otolaryngologists frequently pack both nasal cavities with
different types of nasal packing. Despite all its advantages,
nasal packing is also associated with some disadvantages. To
avoid these issues, many surgeons use suturing techniques to
obviate the need for packing after surgery.
Objective: To determine the efficacy and safety of trans-septal
suture technique in preventing complications and decreasing
morbidity after septoplasty in comparison with nasal packing.
Patients and methods: Prospective comparative study. This
study was conducted in the department of Otolaryngology -
Head and Neck Surgery, Rizgary Teaching Hospital - Erbil,
from the 6th of May 2014 to the 30th of November 2014.
A total of 60 patients aged 18-45 years, undergoing septoplasty,
were included in the study. Before surgery, patients were
randomly divided into two equal groups. Group (A) with transseptal
suture technique was compared with group (B) in which
nasal packing with Merocel was done. Postoperative morbidity
in terms of pain, bleeding, postnasal drip, sleep disturbance,
dysphagia, headache and epiphora along with postoperative
complications including septal hematoma, septal perforation,
crustation and synechiae formation were assessed over a follow
up period of four weeks.
Results: Out of 60 patients, 37 patients were males (61.7%)
and 23 patients were females (38.3%). Patients with nasal
packing had significantly more postoperative pain (P<0.05)><0.05). There was no significant difference between
the two groups with respect to nasal bleeding, septal
hematoma, septal perforation, crustation and synechiae
formation.
Conclusion: Septoplasty can be safely performed using transseptal
suturing technique without nasal packing.
The basic reason behind the need to
monitor water quality is to verify whether the examined
water quality is suitable for intended usage or not. This
study is conducted on Al -Shamiya al- sharqi drain in
Diwaniya city in Iraq to make valid assessment for the
level of parameters measured and to realize their effects
on irrigation. In order to assess the drainage water
quality for irrigation purposes with a high accuracy, the
Irrigation Water Quality Index (IWQI) will be examined
and upgraded (integrated with GIS) to make a
classification for drainage water. For this purpose, ten
samples of drainage water were taken from different ten
location of the stuay area. The collected samples were
analyzed chemically for different elements which affect
water quality for irrigation.These elements are :
Calcium(Ca+2), Sodium(Na+
), Magnesium(Mg+2),
Chloride( ), Potassium(K+
), Bicarbonate(HCO3),
Nitrate(NO3), Sulfate( , Phosphate( , Electrical
Conductivity(EC), Total Dissolved Solids (TDS), Total
Suspended Solids (TSS) and pH-values (PH). Sodium
Adsorption Ratio (SAR) and Sodium Content (Na%)
have been also calculated. Results suggest that, the use of
GIS and Water Quality Index (WQI) methods could
provide an extremely interesting as well as efficient tool
to water resource management. The results analysis of
(IWQI) maps confirms that: 52% of the drainage water
in study area falls within the "Low restriction" (LR) and
47%of study area has water with (Moderate
restriction)(MR),While 1% of drainage water in the
study area classified as (Sever restriction) (SR). So, the
drainage water should be used with the soil having high
permeability with some constraints imposed on types of
plant for specified tolerance of salts
The cable-hoisting method and rail cable-lifting
method are widely used in the construction of suspension bridge.
This paper takes a suspension bridge in Hunan as an example,
and expounds the two construction methods, and analyzes their
respective merits and disadvantages.
This paper presents the details on the
experimental investigation carried out to get the desired fresh
properties of the SCC. Tests were performed on various mixtures
to obtain the required SCC. In the present research work we
have replaced 15% of cement with class F fly ash. By varying the
quantity of water and sand the mortar mix was prepared. Later
varying percentage of coarse aggregate was added to the mortar
to obtain the desired SCC.
The batteries used in electric and hybrid vehicles
consists of several cells with voltages between 3.6V battery and
4.2 V in series or parallel combinations of configurations for
obtaining the necessary available voltages in the operation of a
hybrid electric vehicle. How malfunction of a single cell affects
the behavior of the entire battery pack, BMS main function is to
protect individual cells against over-discharge, overload or
overheating. This is done by correct balancing of the cells. In
addition BMS estimates the battery charge status
This project aims at using (PD-MCPWM) Phase
disposition multi carrier pulse width modulation technique to
reduce leakage current in a transformerless cascaded multilevel
inverter for PV systems. Advantages of transformerless PV
inverter topology is as follows, simple structure, low weight and
provides higher efficiency , but however this topology provides a
path for the leakage current to flow through the parasitic
capacitance formed between the PV module and the ground.
Modulation technique reduces leakage current with an added
advantage without adding any extra components.
Many people in Africa depend on water from
rivers and borehole, but purity of the drinking water from these
sources remains questionable. Mudzira River being the longest
River in a village called Vimtim located in Mubi North Local
government area in Adamawa State was studied in the months of
September to December, 2012 to ascertain the suitability of the
water for human consumption and other related uses. Five study
point: inlet (A, B), middle (C) and out let (D, E) were adopted for
monitoring the physico-chemical parameters using standard
procedures. The mean total temperature values were A (25.000C),
B (24.500C), C (25.500C), D (24.000C) and E (24.000C. Average P
H
values were A (8.00), B (7.87), C (8.20) D (8.37) and E (8.13). The
average conductivity values were A (73.90
1 cms
), B
(73.11
1 cms
), D (74.00
1 cms
) and E (73. 80
1 cms
). The
average total dissolves solid value of each sample were A (17.10),
B (17.10), C (20.00) D (21.64) and E (21.60.). The average
turbidity value of sample were A (47.00), B (47.00), C (50.00) D
(53.00) and E (50.00). Average total hardness value are A
(20.00mg/l), B (20.00mg/L) C (24.00mg/L), D (20.00mg/L) and E
(20.00mg/L). The average chloride content were A (12mg/L), B
(16mg/L), C (12 mg/L) D (16mg/L) and E (16mg/L). The average
calcium content were A (0.3mg/L) B (0.4mg/L), C (0.3mg/L), D
(0.3mg/L) and E (0.2mg/L). The average content of magnesium
were A (12mg/L), B (16mg/L), C (16Mg/L), D (12mg/L), E
(12mg/L). The lead content of River Mudzira water was
negligible. The mean coliform count were A (4), B (3), C (6), D
(7), and E (4).The values of the parameters studied were within
the WHO/NAFDAC recommended standards, excepts for total
coliform levels. In conclusion Vimtim residents consuming
untreated water from River Mudzira are potentially exposed to
possible acute, sub chronic or even chronic water borne diseases
like typhoid fever, dysentery, diarrhea etc.
More from International Journal of Technical Research & Application (20)
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DESIGN AND IMPLEMENTATION OF OFDM SYSTEM AND REDUCTION OF INTER-CARRIER INTERFERENCE
1. International Journal of Technical Research and Applications e-ISSN: 2320-8163,
www.ijtra.com Volume 2, Issue 4 (July-Aug 2014), PP. 173-175
173 | P a g e
DESIGN AND IMPLEMENTATION OF OFDM
SYSTEM AND REDUCTION OF INTER-CARRIER
INTERFERENCE
Gaurav Verma1, Navneet Singh2
1Research Scholar. JCDMCOE, Sirsa
2Assistance Professor, JCDMCOE, Sirsa
gaurav.vermamec@gmail.com
Abstract- 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.
Index Terms- Inerter Carrier Interference, multicarrier
frequency, self-cancellation, Phase noise.
I. INTRODUCTION
OFDM[1] is a frequency-division multiplexing (FDM) scheme
used as a digital multi-carrier modulation method. A large
number of closely spaced orthogonal sub-carrier signals are
used to carry data on several parallel data streams or channels.
Each sub-carrier is modulated with a conventional modulation
scheme (such as quadrature amplitude modulation or phase-
shift keying) at a low symbol rate, maintaining total data rates
similar to conventional single-carrier modulation schemes in
the same bandwidth.
The primary advantage of OFDM over single-carrier schemes
is its ability to cope with severe channel conditions (for
example,attenuation of high frequencies in a long copper wire,
narrowband interference and frequency-selective fading due
to multipath) without complex equalization filters.
Channel equalization is simplified because OFDM may be
viewed as using many slowly modulated narrow band signals
rather than one rapidly modulated wideband signal. The low
symbol rate makes the use of a guard interval between
symbols affordable, making it possible to eliminate inter
symbol interference (ISI) and utilize echoes and time-
spreading (on analogue TV these are visible as ghosting and
blurring, respectively) to achieve a diversity gain, i.e. a signal-
to-noise ratio improvement. This mechanism also facilitates
the design of single frequency networks (SFNs), where several
adjacent transmitters send the same signal simultaneously at
the same frequency, as the signals from multiple distant
transmitters may be combined constructively, rather than
interfering as would typically occur in a traditional single-
carrier system.OFDM is a special form of multicarrier
modulation technique which is used to generate waveforms
that are mutually orthogonal and then distributes the data over
a large number of carriers that are spaced apart at precise
frequencies. This spacing provides the "orthogonality" in this
technique which prevents the demodulators from seeing
frequencies other than their own. In an OFDM scheme, a large
number of orthogonal, overlapping, narrow band subcarriers
are transmitted in parallel. These carriers divide thea vailable
transmission bandwidth. The separation of the subcarriers is
such that there is a very compact spectral utilization. With
OFDM, it is possible to have overlapping sub channels in the
frequency domain (Figure 1), thus increasing the transmission
rate.
Fig.1:- power spectrum of the transmitted signal
In order to avoid a large number of modulators and filters at
the transmitter and complementary filters and demodulators at
the receiver, it is desirable to be able to use modern digital
signal processing techniques, such as fast Fourier transform
(FFT). OFDM is a promising candidate for achieving high
data rates in mobile environment because of its multicarrier
modulation technique and ability to convert a frequency
selective fading channel into several nearly flat fading
channels. This technology has been chosen as the transmission
method of many standards, such as Digital Subscriber Line
(DSL), European Digital Audio and Video Broadcasting
terrestrial (DAB/DVB-T), European HIPERLAN/2 and IEEE
802.11 a/g for wireless local area networks (WLAN),
Worldwide Interoperability for Microwave Access (WiMAX),
etc. However, OFDM systems exhibit a sensitivity to phase
noise higher than single carrier modulations due to its long
symbol period. Because carriers are kept very close to each
2. International Journal of Technical Research and Applications e-ISSN: 2320-8163,
www.ijtra.com Volume 2, Issue 4 (July-Aug 2014), PP. 173-175
174 | P a g e
other, OFDM is very sensitive to distortion that may remove
the orthogonality between carriers.
Phase noise can cause several types of signal degradation that
are usually very difficult to quantify analytically. When the
modulation experiences phase noise, it encounters two
problems:
a) A common phase rotation over all the carrier
frequencies which rotate the entire signal space for a
given OFDM symbol
b) Inter-carrier interference due to the loss of
orthogonality between subcarriers.
Especially, the ICI seriously degrades system predominance
because it may break down the orthogonality between
subcarriers.
II. ORTHOGONAL FREQUENCY DIVISION
MULTIPLEXING
Orthogonal Frequency Division Multiplexing [5] is
a technology related to Frequency Division Multiplexing.
With it, many different signalscan be sent over the same
medium, at the same time. Each signal uses a different basis
function. By using the basis function given, the sender and
recipient will then see their signal better, the other signals will
be clearly separated.
Fig.2:-An example o OFDM with 4 different signal shown
in different colour
I. Orthogonality
If two signals are said to be orthogonal then their dot product
is zero. As the subcarriers are orthogonal then the spectrum of
each subcarrier has a null at the center frequency of the other
subcarriers in the system. It is as shown in the figure.2
II. OFDM Generation And Reception
Fig 3 TRANSMITTER
An OFDM carrier signal is the sum of a number of orthogonal
sub-carriers, with baseband data on each sub-carrier being
independently modulated commonly using some type
ofquadrature amplitude modulation (QAM) or phase-shift
keying (PSK). This composite baseband signal is typically
used to modulate a main RF carrier. is a serial stream of
binary digits. By inverse multiplexing, these are first
demultiplexed into parallel streams, and each one mapped
to a (possibly complex) symbol stream using some modulation
constellation (QAM, PSK, etc.). Note that the constellations
may be different, so some streams may carry a higher bit-rate
than others.
An inverse FFT is computed on each set of symbols, giving a
set of complex time-domain samples. These samples are
then quadrature-mixed to passband in the standard way. The
real and imaginary components are first converted to the
analogue domain using digital-to-analogue
converters (DACs); the analogue signals are then used to
modulatecosine and sine waves at the carrier frequency, ,
respectively. These signals are then summed to give the
transmission signal, .
Fig: 4 RECIVER
The receiver picks up the signal , which is then quadrature-
mixed down to baseband using cosine and sine waves at the
carrier frequency. This also creates signals centered on , so
low-pass filters are used to reject these. The baseband signals
are then sampled and digitised using analog-to-digital
converters (ADCs), and a forward FFT is used to convert back
to the frequency domain.
3. International Journal of Technical Research and Applications e-ISSN: 2320-8163,
www.ijtra.com Volume 2, Issue 4 (July-Aug 2014), PP. 173-175
175 | P a g e
This returns parallel streams, each of which is converted to
a binary stream using an appropriate symbol detector. These
streams are then re-combined into a serial stream, , which
is an estimate of the original binary stream at the transmitter.
III. ICI SELF CANCELLATION METHODS
It is seen that the difference between the ICI co-efficient of the
two consecutive sub-carriers is very small. This makes the
basis of ICI self cancellation. Here one data symbol is not
modulated in to one sub-carrier, rather at least in to two
consecutive sub-carriers. If the data symbol =a‘ is modulated
in to the 1st sub-carrier then =-a‘ is modulated in to the 2nd
sub-carrier. Hence the ICI generated between the two sub-
carriers almost mutually cancels each other. This method is
suitable for multipath fading channels as here no channel
estimation is required.
IV. CONCLUSION
In this paper we have calculated the BER and SNR at
different phase noise variance from zero to 10 and we have
seen that when the phase noise variance is increased BER and
SNR performance is decreased as well as we calculated the
BER at SNR=15 db and 20 db. The improved graph as bellow.
Fig 5:- Best BER performance with ICI cancellation at
zero phase noise variance
Fig 6: BER at different phase noise variance at SNR=15db
and 20db
REFERENCES
[1] M.M. Islam, D. Zhang, G. Lu. A geometric method to compute
directionality features for texture images. In proceeding of:
Proceedings of the 2008 IEEE International Conference on
Multimedia and Expo (ICME), 2008.
[2] http://en.wikipedia.org/wiki/Orthogonal_frequency
division_multiplexing
[3] http://en.wikipedia.org/wiki/IEEE_802.11
[4] http://en.wikipedia.org/wiki/HiperLAN
[5] http://en.wikipedia.org/wiki/Interference_(communication)
[6] http://simple.wikipedia.org/wiki/Orthogonal_frequency-
division_multiplexin
[7] http://link.springer.com/article/10.1007%2Fs00034-012-9477-
z#page-1
[8] http://link.springer.com/article/10.1007/s11277-012-0846-
5#page-1
[9] http://ieeexplore.ieee.org/xpl/login.jsp?tp=&arnumber=651124
0&url=http%3A%2F%2Fieeexplore.ieee.org%2Fiel7%2F6506
960%2F6511176%2F06511240.pdf%3Farnumber%3D651124
0
[10] http://ieeexplore.ieee.org/xpl/login.jsp?tp=&arnumber=647154
6&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_
all.jsp%3Farnumber%3D6471546
[11] http://ieeexplore.ieee.org/xpl/login.jsp?tp=&arnumber=613356
3&url=http%3A%2F%2Fieeexplore.ieee.org%2Fiel5%2F6132
211%2F6133457%2F06133563.pdf%3Farnumber%3D613356
3
[12] http://ieeexplore.ieee.org/xpl/login.jsp?tp=&arnumber=541883
6&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_
all.jsp%3Farnumber%3D5418836
[13] http://ieeexplore.ieee.org/xpl/login.jsp?tp=&arnumber=429183
3&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_
all.jsp%3Farnumber%3D4291833
[14] http://ijarcsee.org/index.php/IJARCSEE/article/view/408
[15] http://ieeexplore.ieee.org/xpl/articleDetails.jsp?arnumber=6550
889
[16] http://ieeexplore.ieee.org/xpl/login.jsp?tp=&arnumber=575220
9&url=http%3A%2F%2Fieeexplore.ieee.org%2Fiel5%2F11%2
F5993771%2F05752209.pdf%3Farnumber%3D5752209
[17] http://www.mathworks.in/products/matlab/