This document discusses the bit error rate (BER) performance of orthogonal frequency division multiplexing (OFDM) in cognitive radio networks over Rayleigh fading channels. It analyzes the signal to noise ratio of OFDM and proposes two pulse shaping approaches, improved sinc power pulses and raised cosine filters, to reduce inter-carrier interference and minimize BER. Simulation results using MATLAB show that applying these inter-carrier interference cancellation schemes can improve BER performance.
IJERA (International journal of Engineering Research and Applications) is International online, ... peer reviewed journal. For more detail or submit your article, please visit www.ijera.com
Comparative performance analysis of different modulation techniques for papr ...IJCNCJournal
One of the most important multi-carrier tran
smission techniques used in the latest wireless com
munication
arena is known as Orthogonal Frequency Division Mul
tiplexing (OFDM). It has several characteristics
such as providing greater immunity to multipath fad
ing & impulse noise, eliminating Inter Symbol
Interference (ISI) & Inter Carrier Interference (IC
I) using a guard interval known as Cyclic Prefix (C
P). A
regular difficulty of OFDM signal is high peak to a
verage power ratio (PAPR) which is defined as the r
atio
of the peak power to the average power of OFDM Sign
al. An improved design of amplitude clipping &
filtering technique of us previously reduced signif
icant amount of PAPR with slightly increase bit err
or rate
(BER) compare to an existing method in case of Quad
rature Phase Shift Keying (QPSK) & Quadrature
Amplitude Modulation (QAM). This paper investigates
a comparative performance analysis of the differen
t
higher order modulation techniques on that design.
A modified design of acf operation for reducing papr of ofdm signalijngnjournal
Next generation wireless communication technology long term evolution (LTE) has implemented
orthogonal frequency division multiplexing (OFDM) technique as a strong candidate for radio access
systems. It has several attributes such as providing robustness to multipath fading & impulse noise,
eliminating intersymbol interference (ISI), inter carrier interference (ICI) & the need for equalizers. The
major challenging issue of OFDM technique is the high peak to average power ratio (PAPR) which is
defined as the ratio of the peak power to the average power of the OFDM signal. A trade-off is
necessary for reducing PAPR with increasing bit error rate (BER), computational complexity or data rate
loss etc. In this paper, a moderately modified design of amplitude clipping & filtering operation (ACF) is
proposed and implemented which shows the significant improvement in case of PAPR reduction for both
quadrature phase shift keying (QPSK) & quadrature amplitude modulation (QAM) while increasing slight
BER match up to to an existing method.
PAPR Reduction in OFDM using Active and Non-Active ChannelsIOSR Journals
Abstract : According to the request of advance communication field there should be high data rate in addition to both power efficiency and lower bit error rate. This request of high data rate can be achieved by the multi carrier modulation scheme using the OFDM technique. But the great drawback of the OFDM technique is its high peak to average power ratio (PAPR). High PAPR reduces OFDM signals by driving the analog amplifier to work in the nonlinear region, changing this way the signal and making the amplifier to consume more power. To reduce the PAPR methods exist which adjust or present new signals to battle large signal peaks. The methods which use data carrying channels are called active channel methods and which use redundant channel are called non active channel methods. This work deals with reduction of the PAPR of OFDM signal using both Active and Non Active Channels. Clipping technique has been applied to active channels and Tone reservation has been applied to Non Active Channels. By using both channels we can get considerable reduction in PAPR. Keywords:Orthogonal Frequency Division Multiplexing (OFDM), Peak to Average Power Ratio (PAPR), Power Amplifier (PA).
Performance comparison of two clipping based filtering methods for papr reduc...ijmnct
The growth of wireless communication technologies has been producing the intense demand for high-speed,
efficient, reliable voice & data communication. As a result, third generation partnership project (3GPP)
has implemented next generation wireless communication technology long term evolution (LTE) which is
designed to increase the capacity and speed of existing mobile telephone & data networks. LTE has
adopted a multicarrier transmission technique known as orthogonal frequency division multiplexing
(OFDM). OFDM meets the LTE requirement for spectrum flexibility and enables cost-efficient solutions for
very wide carriers. One major generic problem of OFDM technique is high peak to average power ratio
(PAPR) which is defined as the ratio of the peak power to the average power of the OFDM signal. A
trade-off is necessary for reducing PAPR with increasing bit error rate (BER), computational complexity or
data rate loss etc. In this paper, two clipping based filtering methods have been implemented & also
analyzed their modulation effects on reducing PAPR.
Study and Analysis Capacity of MIMO Systems for AWGN Channel Model ScenariosIJERA Editor
Future wireless communication systems can utilize the spatial properties of the wireless channel to enhance the spectral efficiency and therefore increases its channel capacity. This can be designed by deploying multiple antennas at both the transmitter side and receiver side. The basic measure of performance is the capacity of a channel; the maximum rate of communication for which arbitrarily small error probability can be achieved. The AWGN (additive white Gaussian noise) channel introduces the notion of capacity through a heuristic argument. The AWGN channel is then used as a basic building block to check the capacity of wireless fading channels in contrast to the AWGN channel. There is no single definition of capacity for fading channels that is applicable in all situations. Several notions of capacity are developed, and together they form a systematic study of performance limits of fading channels. The various capacity measures allow us to observe clearly the various types of resources available in fading channels: degrees of freedom, power and diversity. The MIMO systems capacity can be enhanced linearly with large the number of antennas. This paper elaborates the study of MIMO system capacity using the AWGN Channel Model, Channel Capacity, Channel Fast Fading, Spatial Autocorrelation and Power delay profile for various channel environments.
IJERA (International journal of Engineering Research and Applications) is International online, ... peer reviewed journal. For more detail or submit your article, please visit www.ijera.com
Comparative performance analysis of different modulation techniques for papr ...IJCNCJournal
One of the most important multi-carrier tran
smission techniques used in the latest wireless com
munication
arena is known as Orthogonal Frequency Division Mul
tiplexing (OFDM). It has several characteristics
such as providing greater immunity to multipath fad
ing & impulse noise, eliminating Inter Symbol
Interference (ISI) & Inter Carrier Interference (IC
I) using a guard interval known as Cyclic Prefix (C
P). A
regular difficulty of OFDM signal is high peak to a
verage power ratio (PAPR) which is defined as the r
atio
of the peak power to the average power of OFDM Sign
al. An improved design of amplitude clipping &
filtering technique of us previously reduced signif
icant amount of PAPR with slightly increase bit err
or rate
(BER) compare to an existing method in case of Quad
rature Phase Shift Keying (QPSK) & Quadrature
Amplitude Modulation (QAM). This paper investigates
a comparative performance analysis of the differen
t
higher order modulation techniques on that design.
A modified design of acf operation for reducing papr of ofdm signalijngnjournal
Next generation wireless communication technology long term evolution (LTE) has implemented
orthogonal frequency division multiplexing (OFDM) technique as a strong candidate for radio access
systems. It has several attributes such as providing robustness to multipath fading & impulse noise,
eliminating intersymbol interference (ISI), inter carrier interference (ICI) & the need for equalizers. The
major challenging issue of OFDM technique is the high peak to average power ratio (PAPR) which is
defined as the ratio of the peak power to the average power of the OFDM signal. A trade-off is
necessary for reducing PAPR with increasing bit error rate (BER), computational complexity or data rate
loss etc. In this paper, a moderately modified design of amplitude clipping & filtering operation (ACF) is
proposed and implemented which shows the significant improvement in case of PAPR reduction for both
quadrature phase shift keying (QPSK) & quadrature amplitude modulation (QAM) while increasing slight
BER match up to to an existing method.
PAPR Reduction in OFDM using Active and Non-Active ChannelsIOSR Journals
Abstract : According to the request of advance communication field there should be high data rate in addition to both power efficiency and lower bit error rate. This request of high data rate can be achieved by the multi carrier modulation scheme using the OFDM technique. But the great drawback of the OFDM technique is its high peak to average power ratio (PAPR). High PAPR reduces OFDM signals by driving the analog amplifier to work in the nonlinear region, changing this way the signal and making the amplifier to consume more power. To reduce the PAPR methods exist which adjust or present new signals to battle large signal peaks. The methods which use data carrying channels are called active channel methods and which use redundant channel are called non active channel methods. This work deals with reduction of the PAPR of OFDM signal using both Active and Non Active Channels. Clipping technique has been applied to active channels and Tone reservation has been applied to Non Active Channels. By using both channels we can get considerable reduction in PAPR. Keywords:Orthogonal Frequency Division Multiplexing (OFDM), Peak to Average Power Ratio (PAPR), Power Amplifier (PA).
Performance comparison of two clipping based filtering methods for papr reduc...ijmnct
The growth of wireless communication technologies has been producing the intense demand for high-speed,
efficient, reliable voice & data communication. As a result, third generation partnership project (3GPP)
has implemented next generation wireless communication technology long term evolution (LTE) which is
designed to increase the capacity and speed of existing mobile telephone & data networks. LTE has
adopted a multicarrier transmission technique known as orthogonal frequency division multiplexing
(OFDM). OFDM meets the LTE requirement for spectrum flexibility and enables cost-efficient solutions for
very wide carriers. One major generic problem of OFDM technique is high peak to average power ratio
(PAPR) which is defined as the ratio of the peak power to the average power of the OFDM signal. A
trade-off is necessary for reducing PAPR with increasing bit error rate (BER), computational complexity or
data rate loss etc. In this paper, two clipping based filtering methods have been implemented & also
analyzed their modulation effects on reducing PAPR.
Study and Analysis Capacity of MIMO Systems for AWGN Channel Model ScenariosIJERA Editor
Future wireless communication systems can utilize the spatial properties of the wireless channel to enhance the spectral efficiency and therefore increases its channel capacity. This can be designed by deploying multiple antennas at both the transmitter side and receiver side. The basic measure of performance is the capacity of a channel; the maximum rate of communication for which arbitrarily small error probability can be achieved. The AWGN (additive white Gaussian noise) channel introduces the notion of capacity through a heuristic argument. The AWGN channel is then used as a basic building block to check the capacity of wireless fading channels in contrast to the AWGN channel. There is no single definition of capacity for fading channels that is applicable in all situations. Several notions of capacity are developed, and together they form a systematic study of performance limits of fading channels. The various capacity measures allow us to observe clearly the various types of resources available in fading channels: degrees of freedom, power and diversity. The MIMO systems capacity can be enhanced linearly with large the number of antennas. This paper elaborates the study of MIMO system capacity using the AWGN Channel Model, Channel Capacity, Channel Fast Fading, Spatial Autocorrelation and Power delay profile for various channel environments.
Comparative evaluation of bit error rate for different ofdm subcarriers in ra...ijmnct
In the present situation, the expectation about the quality of signals in wireless communication is as high as possible. This quality issue is dependent upon the different communication parameters. One of the most important issues is to reduce the bit error rate (BER) to enhance the performance of the system. This paper provides a comparative analysis on the basis of this bit error rate. I have compared the BER for different number of subcarriers in OFDM system for BPSK modulation scheme. I have taken 6 varieties of data subcarriers to analyze this comparison. Here my target is to reach at the lowest level of BER for BPSK modulation. That is achieved at 2048 number of subcarriers.
Comparative Analysis of PAPR Reduction Techniques in OFDM Using Precoding Tec...IJSRD
In this modern era, Orthogonal Frequency Division Multiplexing (OFDM) has been proved to be an explicit promising technique for wired and wireless systems because of its several advantages like high spectral efficiency, robustness against frequency selective fading, relatively simple receiver implementation etc. Besides having a number of advantages OFDM suffers from few disadvantages like high Peak to Average Power Ratio (PAPR), Intercarrier Interference (ICI), Intersymbol Interference (ISI) etc. These detrimental effects, if not compensated properly and timely, can result in system performance degradation. This paper mainly concentrates on reduction of PAPR.A comparisons have been made between various precoding techniques against conventional OFDM.
A Hybrid PAPR Reduction Scheme for OFDM System ijmnct
Orthogonal frequency division multiplexing (OFDM) i
s considered as most efficient technique for future
wireless communication systems due to its higher sp
ectral bandwidth efficiency, robustness to frequenc
y
selective fading channels, etc. However, the succes
sful implementation of the OFDM system necessitates
several difficulties. The biggest disadvantage to w
ork with OFDM system is its high peak-to-average po
wer
ratio PAPR leadsto severe inter carrier interferenc
e, out-of-band radiation, and poor bit error rate
performance due to the nonlinearity of the high pow
er amplifier. In this paper, a novel hybrid techniq
ue is
proposed to reduce PAPR further and comparison has
been done with conventional techniques as well.
Simulated results are presentedconfirm theoretical
results.MATLAB 7.5 is used to simulate the results
for system parametersconsidered.
Narrowband Spectrum Sensing for Different Fading Channels for Cognitive Radio...IJMERJOURNAL
Abstract: Nowadays the demand of applications of wireless communication has increased rapidly which causes the scarcity of radio spectrum. To empower future wireless communication services, the radio spectrum management is a very important factor. Cognitiveradio is a promising technology which provides an innovative way to improve utilization efficiency of available electromagnetic spectrum by sensing spectrum and shares it without harmful interference to other users. Narrowband spectrum sensing is the technique where the bandwidth of active primary transmitter in the vicinity of cognitive radio is less than the coherence bandwidth of channel. Fading is one of the greatest impairment of narrowband spectrum sensing. It is deflection of the attenuation. It influences a signal over certain propagation media.A communication channel that experiences fading isknown as fading channel. The effects of fading can be reduced by several fading models. In this paper, performanceanalysis of several realistic fading models on narrowband channel using energy detection method is employed. Finally, performance comparison of various fading models is guaranteed through simulation.
Peak-to-Average Power Ratio Reduction in NC-OFDM based Cognitive Radio.CSCJournals
This paper presents a novel technique for reducing the peak-to-average power ratio (PAPR) in non-contiguous bands spectrum of Orthogonal Frequency Division Multiplexing (OFDM) based Cognitive Radio (CR). The proposed system exposed to carry the past channel information and the spectrum sensing to utilize the radio spectrum as well as achieving an appropriate PAPR reduction and maintaining end-to-end throughput performance by using a set of approaches in the current CR environment. The simulation results for PAPR reduction has shown that higher constellation modulation schemes are better compared to lower constellation modulation schemes.
A SURVEY ON OPTIMIZATION BASED SPECTRUM SENSING TECHNIQUES TO REDUCE ISI AND ...IJNSA Journal
Cognitive radio is emerging technologies in OFDM based wireless systems which are very important for spectrum sensing. By using cognitive radio (CR) high data can be transferred with low bit error rate. The key idea of OFDM is to split the total transmission bandwidth into the subcarriers which further reduce the intersymbol interference (ISI) and peak to average power ratio(PAPR) in the signal. There are many optimization based spectrum sensing techniques are existing for efficient sensing purpose but each has its own advantages and disadvantages. This leads to start the comprehensive study for reducing PAPR and ISI(Intersymbol interference) in terms of FPGA based partial configuration. In the first part of review OFDM characteristics of the signal has compared with several optimizations based ISI reduction techniques. The second part is to compare the various spectrum sensing techniques in cognitive radio engine and its application in FPGA.
SLM-PTS BASED PAPR REDUCTION TECHNIQUES IN OFDM SYSTEMHariniChaganti1
Signals, which were initially sent in the analog domain, are being sent more and more in the digital domain these days. For better transmission, even single–carrier waves are being replaced by multi–carriers. Multi-carrier
systems like OFDM are now – a – days being implemented commonly. In the OFDM system,
orthogonally placed subcarriers are used to carry the data from the transmitter end to the receiver end. The presence of a guard band in this system deals with the problem of ISI and noise is minimized by a larger number of sub–carriers. But the large Peak– to –Average Power Ratio of these signal have some undesirable effects on the system. The Peak-to-Average Power Ratio is the ratio between the maximum power and average power of a complex passband signal. It causes many disadvantages like band-in and band-out variation, low signal to quantization noise ratio, low efficiency of power amplifier, etc. Hence, it is necessary to reduce PAPR in OFDM for its efficient use.
In this project, the main objective is to study the basics of an OFDM System and analyze and
simulate various methods such as clipping and filtering, selected mapping, Partial transmit sequence
to reduce the PAPR in the system and compare these techniques with and without PAPR reduction to
obtain an efficient technique so that this system can be used more commonly and effectively.
New Adaptive Cooperative-MIMO for LTE Technologyijtsrd
Multiple Input Multiple Output (MIMO) systems have been widely used in an area of wireless cellular communication system, providing the both increased capacity and reliability. However, the use of multiple antennas in mobile terminals may not be very practical due to limited space and other implementation issues. In this paper, cooperative MIMO has been used in a way to optimise the implementation and working of conventional MIMO systems in terms of BER and Spectral Efficiency while maintaining a minimal number of antennas on each handset. Cooperative MIMO with V-BLAST transmission over Rayleigh flat fading channels and amplify and forward protocol with one relay node for modulation techniques like BPSK, QPSK, QAM using various decoding techniques has been analysed. Decoding algorithms like ZF, MMSE and ML have been analysed with respect to their BER performances. Since, there is throughput loss in cooperative MIMO due to extra resources required for relaying, adaptive modulation has been used with C-MIMO to meet the demands for high data rates in Long Term Evolution Network. Sukhreet Kaur | Dr. Amita Soni"New Adaptive Cooperative-MIMO for LTE Technology" Published in International Journal of Trend in Scientific Research and Development (ijtsrd), ISSN: 2456-6470, Volume-2 | Issue-4 , June 2018, URL: http://www.ijtsrd.com/papers/ijtsrd12919.pdf http://www.ijtsrd.com/engineering/electronics-and-communication-engineering/12919/new-adaptive-cooperative-mimo-for-lte-technology/sukhreet-kaur
Capacity Enhancement of MIMO-OFDM System in Rayleigh Fading ChannelIOSR Journals
MIMO-OFDM system in Rayleigh Fading Channel is very popular technique for mobile
communication now a day’s for research. Here we want increase the capacity of MIMO-OFDM of system by
using adaptive modulation, Algebraic Space-Time Codes (ASTC) encoder for MIMO Systems are based on
quaternion algebras .we found that ergodic capacity has some limitation which reduce the system’s
performance to overcome this we use ASTC code . ASTC code are full rank, full rate and non vanishing constant
minimum determinant for increasing spectral efficiency and reducing Peak to Average Power Ratio (PAPR) .
Hybrid approach to solve the problem of papr in ofdm signal a surveyeSAT Journals
“Orthogonal frequency division multiplexing
method used to achieve the today’s need of wireless communication
3GPP Association for the use of LTE. The
higher data rate, higher bit rate, mitigated delay spread, lower multipath distortion,
OFDM system has few major issues associated with
ratio (PAPR)” associated with the signal.
interleaved OFDM, selective mapping (SLM)
windowing, clipping, filtering, tone rejection(TR), tone injection(TI), compandin
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.
Comparative evaluation of bit error rate for different ofdm subcarriers in ra...ijmnct
In the present situation, the expectation about the quality of signals in wireless communication is as high as possible. This quality issue is dependent upon the different communication parameters. One of the most important issues is to reduce the bit error rate (BER) to enhance the performance of the system. This paper provides a comparative analysis on the basis of this bit error rate. I have compared the BER for different number of subcarriers in OFDM system for BPSK modulation scheme. I have taken 6 varieties of data subcarriers to analyze this comparison. Here my target is to reach at the lowest level of BER for BPSK modulation. That is achieved at 2048 number of subcarriers.
Comparative Analysis of PAPR Reduction Techniques in OFDM Using Precoding Tec...IJSRD
In this modern era, Orthogonal Frequency Division Multiplexing (OFDM) has been proved to be an explicit promising technique for wired and wireless systems because of its several advantages like high spectral efficiency, robustness against frequency selective fading, relatively simple receiver implementation etc. Besides having a number of advantages OFDM suffers from few disadvantages like high Peak to Average Power Ratio (PAPR), Intercarrier Interference (ICI), Intersymbol Interference (ISI) etc. These detrimental effects, if not compensated properly and timely, can result in system performance degradation. This paper mainly concentrates on reduction of PAPR.A comparisons have been made between various precoding techniques against conventional OFDM.
A Hybrid PAPR Reduction Scheme for OFDM System ijmnct
Orthogonal frequency division multiplexing (OFDM) i
s considered as most efficient technique for future
wireless communication systems due to its higher sp
ectral bandwidth efficiency, robustness to frequenc
y
selective fading channels, etc. However, the succes
sful implementation of the OFDM system necessitates
several difficulties. The biggest disadvantage to w
ork with OFDM system is its high peak-to-average po
wer
ratio PAPR leadsto severe inter carrier interferenc
e, out-of-band radiation, and poor bit error rate
performance due to the nonlinearity of the high pow
er amplifier. In this paper, a novel hybrid techniq
ue is
proposed to reduce PAPR further and comparison has
been done with conventional techniques as well.
Simulated results are presentedconfirm theoretical
results.MATLAB 7.5 is used to simulate the results
for system parametersconsidered.
Narrowband Spectrum Sensing for Different Fading Channels for Cognitive Radio...IJMERJOURNAL
Abstract: Nowadays the demand of applications of wireless communication has increased rapidly which causes the scarcity of radio spectrum. To empower future wireless communication services, the radio spectrum management is a very important factor. Cognitiveradio is a promising technology which provides an innovative way to improve utilization efficiency of available electromagnetic spectrum by sensing spectrum and shares it without harmful interference to other users. Narrowband spectrum sensing is the technique where the bandwidth of active primary transmitter in the vicinity of cognitive radio is less than the coherence bandwidth of channel. Fading is one of the greatest impairment of narrowband spectrum sensing. It is deflection of the attenuation. It influences a signal over certain propagation media.A communication channel that experiences fading isknown as fading channel. The effects of fading can be reduced by several fading models. In this paper, performanceanalysis of several realistic fading models on narrowband channel using energy detection method is employed. Finally, performance comparison of various fading models is guaranteed through simulation.
Peak-to-Average Power Ratio Reduction in NC-OFDM based Cognitive Radio.CSCJournals
This paper presents a novel technique for reducing the peak-to-average power ratio (PAPR) in non-contiguous bands spectrum of Orthogonal Frequency Division Multiplexing (OFDM) based Cognitive Radio (CR). The proposed system exposed to carry the past channel information and the spectrum sensing to utilize the radio spectrum as well as achieving an appropriate PAPR reduction and maintaining end-to-end throughput performance by using a set of approaches in the current CR environment. The simulation results for PAPR reduction has shown that higher constellation modulation schemes are better compared to lower constellation modulation schemes.
A SURVEY ON OPTIMIZATION BASED SPECTRUM SENSING TECHNIQUES TO REDUCE ISI AND ...IJNSA Journal
Cognitive radio is emerging technologies in OFDM based wireless systems which are very important for spectrum sensing. By using cognitive radio (CR) high data can be transferred with low bit error rate. The key idea of OFDM is to split the total transmission bandwidth into the subcarriers which further reduce the intersymbol interference (ISI) and peak to average power ratio(PAPR) in the signal. There are many optimization based spectrum sensing techniques are existing for efficient sensing purpose but each has its own advantages and disadvantages. This leads to start the comprehensive study for reducing PAPR and ISI(Intersymbol interference) in terms of FPGA based partial configuration. In the first part of review OFDM characteristics of the signal has compared with several optimizations based ISI reduction techniques. The second part is to compare the various spectrum sensing techniques in cognitive radio engine and its application in FPGA.
SLM-PTS BASED PAPR REDUCTION TECHNIQUES IN OFDM SYSTEMHariniChaganti1
Signals, which were initially sent in the analog domain, are being sent more and more in the digital domain these days. For better transmission, even single–carrier waves are being replaced by multi–carriers. Multi-carrier
systems like OFDM are now – a – days being implemented commonly. In the OFDM system,
orthogonally placed subcarriers are used to carry the data from the transmitter end to the receiver end. The presence of a guard band in this system deals with the problem of ISI and noise is minimized by a larger number of sub–carriers. But the large Peak– to –Average Power Ratio of these signal have some undesirable effects on the system. The Peak-to-Average Power Ratio is the ratio between the maximum power and average power of a complex passband signal. It causes many disadvantages like band-in and band-out variation, low signal to quantization noise ratio, low efficiency of power amplifier, etc. Hence, it is necessary to reduce PAPR in OFDM for its efficient use.
In this project, the main objective is to study the basics of an OFDM System and analyze and
simulate various methods such as clipping and filtering, selected mapping, Partial transmit sequence
to reduce the PAPR in the system and compare these techniques with and without PAPR reduction to
obtain an efficient technique so that this system can be used more commonly and effectively.
New Adaptive Cooperative-MIMO for LTE Technologyijtsrd
Multiple Input Multiple Output (MIMO) systems have been widely used in an area of wireless cellular communication system, providing the both increased capacity and reliability. However, the use of multiple antennas in mobile terminals may not be very practical due to limited space and other implementation issues. In this paper, cooperative MIMO has been used in a way to optimise the implementation and working of conventional MIMO systems in terms of BER and Spectral Efficiency while maintaining a minimal number of antennas on each handset. Cooperative MIMO with V-BLAST transmission over Rayleigh flat fading channels and amplify and forward protocol with one relay node for modulation techniques like BPSK, QPSK, QAM using various decoding techniques has been analysed. Decoding algorithms like ZF, MMSE and ML have been analysed with respect to their BER performances. Since, there is throughput loss in cooperative MIMO due to extra resources required for relaying, adaptive modulation has been used with C-MIMO to meet the demands for high data rates in Long Term Evolution Network. Sukhreet Kaur | Dr. Amita Soni"New Adaptive Cooperative-MIMO for LTE Technology" Published in International Journal of Trend in Scientific Research and Development (ijtsrd), ISSN: 2456-6470, Volume-2 | Issue-4 , June 2018, URL: http://www.ijtsrd.com/papers/ijtsrd12919.pdf http://www.ijtsrd.com/engineering/electronics-and-communication-engineering/12919/new-adaptive-cooperative-mimo-for-lte-technology/sukhreet-kaur
Capacity Enhancement of MIMO-OFDM System in Rayleigh Fading ChannelIOSR Journals
MIMO-OFDM system in Rayleigh Fading Channel is very popular technique for mobile
communication now a day’s for research. Here we want increase the capacity of MIMO-OFDM of system by
using adaptive modulation, Algebraic Space-Time Codes (ASTC) encoder for MIMO Systems are based on
quaternion algebras .we found that ergodic capacity has some limitation which reduce the system’s
performance to overcome this we use ASTC code . ASTC code are full rank, full rate and non vanishing constant
minimum determinant for increasing spectral efficiency and reducing Peak to Average Power Ratio (PAPR) .
Hybrid approach to solve the problem of papr in ofdm signal a surveyeSAT Journals
“Orthogonal frequency division multiplexing
method used to achieve the today’s need of wireless communication
3GPP Association for the use of LTE. The
higher data rate, higher bit rate, mitigated delay spread, lower multipath distortion,
OFDM system has few major issues associated with
ratio (PAPR)” associated with the signal.
interleaved OFDM, selective mapping (SLM)
windowing, clipping, filtering, tone rejection(TR), tone injection(TI), compandin
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.
As we know polyester is a synthetic fiber and has
more crystalline structure than natural fibers. In continuous
dyeing of polyester by pad-Thermosol process, there are many
advantages such as bulk production, low-cost, good efficiency etc.
But during dyeing process there is a severe problem occurs that
is dye migration .in order to control the dye migration different
migration inhibitors are used in this project. Both natural and
synthetic migration inhibitors are applied on the 100% polyester
fabric in order to compare that which migration inhibitor hives
better results on the pad-Thermosol process.
After comparing the different properties of the both migration
inhibitors the synthetic inhibitors found more efficient then the
natural one. The following tests were conducted during project:
Migration test, tensile strength, color strength, bending length,
light fatness.
Synthetic migration inhibitors gives better results for the tests
which were conducted .but there is a problem that the synthetic
migration inhibitors are not environmental friendly and they are
costly then natural migration inhibitors.
— A CAPTCHA means "Completely Automated
Public Turing test to tell Computers and Humans Apart". It is a
type of challenge-response test used in computing to determine
whether or not the user is human. CaRP is both a Captcha and a
graphical password scheme. CaRP addresses a number of
security problems altogether, such as online guessing attacks,
relay attacks, and, if combined with dual-view technologies,
shoulder-surfing attacks. Particularly, a CaRP password can be
found only probabilistically by automatic online guessing attacks,
even if the password is in the search set. CaRP also offers an
approach to address the well-known image hotspot problem in
popular graphical password systems, such as PassPoints, which
often leads to weak password choices. Thus, a variant to the
login/password scheme, using graphical scheme was introduced.
But it also suffered due to shoulder-surfing and screen dump
attacks. Thus it introduces a framework to proposed (IPAS)
Implicit Password Authentication System, which is protected to
the common attacks suffered by other authentication schemes.
Globally 165 million children under-five
years of age are stunted. Hence development of local
therapeutic nutritional intervention is recommended by WHO.
Present study was designed to find the efficacy of the
nutritional intervention for the recovery of impaired lipid
metabolism and correlation of weight for height% with
cholesterol, triglyceride in malnourished children. 105 test and
100 control SAM children without infection, of 1 to 5 years of
age and either sex were enrolled. Test group was given
treatment of nutritional intervention therapy, providing 2.5 to
3gm Protein and 90-100 kcal /kg body Weight/day, for the
three months. Their Anthropometric, and Biochemical
parameters were measured before and after the nutritional
therapy. Before the nutritional intervention treatment P values
for Serum Total cholesterol, Triglyceride, Weight for height
%, were insignificant suggestive of similar baseline
characteristics at enrollment. After nutritional intervention
treatment P values for Serum Total cholesterol, Triglyceride,
Weight for height % were highly significant. The r value of
Pearson correlation coefficient for triglycerides in the study
group and its ANOVA model was very significant, showing
poor positive correlation with weight for height % while for
total cholesterol it was found to be insignificant. Depending on
results we conclude that it is the most effective food supplement
for the speedy recovery of the impaired lipid metabolism in
SAM children and the use of weight for height % as a
anthropometric marker for the pre-indication of fatty liver in
malnourished children
The software industry has had significant progress
in recent years. The entire life of software includes two phases:
Production and Maintenance. Software maintenance cost is
increasingly growing and estimates showed that about 90%, if
software life cost is related to its maintenance phase. Extraction
and considering the factors affecting software maintenance cost
help to estimate the cost and reduce it by controlling the factors.
Cost estimation of maintenance phase is necessary to predict the
reliability, improve the productivity, project planning, controlling
and adaptability of the software. Though there are various models
to estimate the maintenance cost of traditional software like
COCOMO, SLIM, Function Point etc., but till now there is no
such model to estimate the maintenance cost using fourth
generation language environment. Software maintenance will
continue to exist in the fourth generation environment, as systems
will still be required to evolve. In this kind of situation there is
needed to develop a model to estimate the maintenance cost using
fourth generation environment. We propose a systematic
approach and development for software maintenance cost
estimation model using fourth generation language environment
on the basis of COCOMO II. This model is based on three
parameters: SMCE with Fourth Generation Language
Environment, ACT (Annual Change Traffic), Technical and NonTechnical
factors which affect the maintenance cost. The
favorable results closely matching and it can be achieved by using
model implementation.
Software testing means to cut errors, reduce
maintenances and to short the cost of software development. Many
software development and testing methods are used from many
past years to improve software quality and software reliability. The
major problem arises in the field of software testing is to find the
best test case to performs testing of software. There are many kind
of testing methods used for making a best case. Teasing is a
important part of software development cycle .The process of
testing is not bounded to detection of ’error’ in software but also
enhances the surety of proper functioning and help to find out the
functional and non functional particularities .Testing activities
focuses on the overall progress of software.
Performance evaluation on the basis of bit error rate for different order of ...ijmnct
Today, we have required to accommodate a large number of users under a single base station. This can be
possible only if we have some flexibility over the spectrum. Previously we have lots of multiplexing methods
to accommodate large number of signals in time and frequency domain. But now we have required to
accommodate a large number of users in the same bandwidth, without any fading over the received signal.
So, orthogonality can be maintained over the frequency response. This technology is now more popular in
the mobile communication domain, called Orthogonal Frequency Division Multiplexing (OFDM). Actually
user data can be converted into the parallel form and then they are modulated using digital modulation
techniques. Finally, they have followed by OFDM Modulator and cyclic prefix can be inserted into the
OFDM symbols. Here, I have worked on the measurement of Bit error rate for different modulation
techniques in OFDM technology. It has been considered that subchannel size is not constant. According to
that I have concluded the overall idea regarding the performance under OFDM technology.
A Potent MIMO–OFDM System Designed for Optimum BER and its Performance Anal...inventionjournals
International Journal of Engineering and Science Invention (IJESI) is an international journal intended for professionals and researchers in all fields of computer science and electronics. IJESI publishes research articles and reviews within the whole field Engineering Science and Technology, new teaching methods, assessment, validation and the impact of new technologies and it will continue to provide information on the latest trends and developments in this ever-expanding subject. The publications of papers are selected through double peer reviewed to ensure originality, relevance, and readability. The articles published in our journal can be accessed online.
A Potent MIMO–OFDM System Designed for Optimum BER and its Performance Anal...inventionjournals
International Journal of Engineering and Science Invention (IJESI) is an international journal intended for professionals and researchers in all fields of computer science and electronics. IJESI publishes research articles and reviews within the whole field Engineering Science and Technology, new teaching methods, assessment, validation and the impact of new technologies and it will continue to provide information on the latest trends and developments in this ever-expanding subject. The publications of papers are selected through double peer reviewed to ensure originality, relevance, and readability. The articles published in our journal can be accessed online.
Orthogonal frequency-division multiplexing (OFDM)
[1] is a method of encoding digital data on multiple carrier
frequencies. OFDM[1] has developed into a popular scheme
for wideband digital communication, whether wireless or
over copper wires, used in applications such as digital television
and audio broadcasting, DSL Internet access, wireless networks,
powerline networks, and 4G mobile communications. In the
Several wireless standards such as IEEE 802.11a[2] and
HiperLAN2[3].The orthogonality of the subcarriers is no longer
maintained which results in ICI (Inter carrier Interference)[4]
.ICI reduction techniques achieve a better SNR and BER in
OFDM at zero phase noise variance . This technique will use a
large number of closely spaced orthogonal subcarriers to avoid
phase noise. It provides high data rates with sufficient robustness
to radio channel damages. A major problem in OFDM is carrier
frequency offset error between the transmitted and received
signals. Due to this the orthogonality of the subcarriers is no
longer maintained which results in ICI (Inter carrier
Interference). In this paper, we used the ICI self-cancellation
technique and reduced the ICI and improved the BER and SNR
we are also calculate the SNR=15db and 20db at different phase
noise variance.
BER Analysis of OFDM Systems with Varying Frequency Offset Factor over AWGN a...rahulmonikasharma
The progressively escalating demand for tremendously high rate data transmission over wireless mediums needsresourcefulconcord of electromagnetic resources considering restrictions like power incorporation, spectrum proficiency, robustness in disparity to multipath propagation and implementation complication. Orthogonal frequency division multiplexing (OFDM) is a favorable approach for upcoming generation wireless communication systems. However its susceptibility to the frequency offset triggered by frequency difference between local oscillator of transmitter and receiver or due to Doppler shift results to Inter Carrier Interference. This delinquent of ICI results inworsening performance of the wireless systems as bit error rate increaseswith increase in value of frequency offset. In this paper simulation results aredemonstratedfor analyzing the effect of varying frequency offset factor on system’s error rate performance.
Effects of filtering on ber performance of an ofdm systemeSAT Journals
Abstract In upcoming generations, wireless communication system requires a higher standard in order to provide high quality of services to customers. Orthogonal Frequency Division Multiplexing (OFDM) is an efficient modulation technique of forthcoming wireless systems which can be implemented easily. In this paper, an effort has been made to analyze how well an OFDM system can perform when a signal is transmitted over an Additive White Gaussian Noise (AWGN) channel using 16 QAM modulation techniques. The performance of OFDM system with pulse shaping filters are also evaluated and results reveal that the pulse shaped OFDM improve the overall performance of the system in terms of BER. We use Different pulse shaping filters such asRaised cosine, FIR Nyquist and SQRT Raised Cosine for analyzingthe Bit Error Rate (BER) performance. Index Terms: AWGN, ICI, OFDM, Bit Error Rate.
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 MIMO-OFDM System Using QOSTBC Code Structure for M-PSKCSCJournals
MIMO-OFDM system has been currently recognized as one of the most competitive technology for 4G mobile wireless systems. MIMO-OFDM system can compensate for the lacks of MIMO systems and give play to the advantages of OFDM system. In this paper, a general Quasi orthogonal space time block code (QOSTBC) structure is proposed for multiple-input multiple-output–orthogonal frequency-division multiplexing (MIMO-OFDM) systems for 4X4 antenna configuration. The signal detection technology used in this paper for MIMO-OFDM system is Zero-Forcing Equalization (linear detection technique). In this paper the analysis of high level of modulations (i.e. M-PSK for different values of M) on MIMO-OFDM system is presented. Here AWGN and Rayleigh channels have been used for analysis purpose and their effect on BER for high data rates have been presented. The proposed MIMO-OFDM system with QOSTBC using 4X4 antenna configuration has better performance in terms of BER vs SNR than the other systems.
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.
Ber performance of ofdm with discrete wavelet transform for time dispersive c...eSAT Publishing House
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
Comparison of Three Different Cancellation Schemes for Orthogonal Frequency D...ijtsrd
Orthogonal Frequency Division Multiplexing OFDM is an exceptional case of Frequency Division Multiplexing. The dilemma of OFDM is its sensitivity to frequency offset between the transmitted and received carrier frequencies. This frequency offset establishes Inter Carrier Interference ICI Cancellation in the OFDM symbol. ICI reduction methods have been had by OFDM. This research considers three ICI self cancellation SC , maximum likelihood ML estimation, and extended Kalman filter EKF method. These three methods are compared in terms of bit error rate performance, bandwidth efficiency, and computational complexity. For high values of the frequency offset and for higher order modulation schemes, the SC method does not as well as the ML and EKF methods. Simulation results using MATLAB software. Ma Khin Saw | Aye Aye Khine ""Comparison of Three Different Cancellation Schemes for Orthogonal Frequency Division Multiplexing (OFDM) System"" Published in International Journal of Trend in Scientific Research and Development (ijtsrd), ISSN: 2456-6470, Volume-3 | Issue-4 , June 2019, URL: https://www.ijtsrd.com/papers/ijtsrd25182.pdf
Paper URL: https://www.ijtsrd.com/engineering/electronics-and-communication-engineering/25182/comparison-of-three-different-cancellation-schemes-for-orthogonal-frequency-division-multiplexing-ofdm-system/ma-khin-saw
Reduction of Frequency offset Using Joint Clock for OFDM Based Cellular Syste...IJRST Journal
This project addresses the problem of clock synchronization between a base station (BS) and a mobile station (MS). A conventional technique for clock synchronization is that the MS clock is derived from the downlink signal originated from a base station. In cellular systems, a base station and mobile stations need to be synchronized before data exchange. Since the base station clock reference is more accurate, a mobile station typically derives its clock reference from the base station. But the carrier frequency offset due to Doppler shift may have harmful effects on the local clock derivation. This project proposes a joint clock and frequency synchronization technique between a base station and a mobile station, which is effective even with Doppler shift. We derive the joint estimation algorithm by analyzing the phase and the amplitude distortion caused by the sampling frequency offset and the carrier frequency offset. Simulation results showing the effectiveness of the proposed algorithm will also be presented.
Analyses and performance of techniques papr reduction for stbc mimo ofdm syst...ijwmn
An OFDM system is combined with multiple-input mult
iple-output (MIMO) in order to increase the
diversity gain and system capacity over the time va
riant frequency-selective channels. However, a maj
or
drawback of MIMO-OFDM system is that the transmitte
d signals on different antennas might exhibit high
peak-to-average power ratio (PAPR).In this paper, w
e present a PAPR analysis reduction of space-time-
block-coded (STBC) MIMO-OFDM system for 4G wireless
networks. Several techniques have been used to
reduce the PAPR of the (STBC) MIMOOFDM system: clip
ping and filtering, partial transmit sequence
(PTS) and selected mapping (SLM). Simulation result
s show that clipping and filtering provides a bette
r
PAPR reduction than the others methods and only SLM
technique conserve the PAPR reduction in
reception part of signal.
Reduction of Outage Probability in Fast Rayleigh Fading MIMO Channels Using OFDMIJERA Editor
Multiple-input multiple-output (MIMO) techniques are used in wireless communications for achieving high spectral efficiency; however, a fast fading spatial channel can increase the outage probability of a MIMO system if not taken care of. This paper investigates the use of orthogonal frequency division multiplexing (OFDM) modulation technique for a MIMO system operating in fast Rayleigh fading channels with the aim of eliminating outage probabilities in the MIMO systems. Simulation results show that the MIMO-OFDM system gives significant reduction in outage probabilities compared to the conventional MIMO system.
Similar to BER PERFORMANCE ANALYSIS OF OFDM IN COGNITIVE RADIO NETWORK IN RAYLEIGH FADING CHANNEL (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
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.
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.
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)
Instructions for Submissions thorugh G- Classroom.pptxJheel Barad
This presentation provides a briefing on how to upload submissions and documents in Google Classroom. It was prepared as part of an orientation for new Sainik School in-service teacher trainees. As a training officer, my goal is to ensure that you are comfortable and proficient with this essential tool for managing assignments and fostering student engagement.
Palestine last event orientationfvgnh .pptxRaedMohamed3
An EFL lesson about the current events in Palestine. It is intended to be for intermediate students who wish to increase their listening skills through a short lesson in power point.
Read| The latest issue of The Challenger is here! We are thrilled to announce that our school paper has qualified for the NATIONAL SCHOOLS PRESS CONFERENCE (NSPC) 2024. Thank you for your unwavering support and trust. Dive into the stories that made us stand out!
Unit 8 - Information and Communication Technology (Paper I).pdfThiyagu K
This slides describes the basic concepts of ICT, basics of Email, Emerging Technology and Digital Initiatives in Education. This presentations aligns with the UGC Paper I syllabus.
Synthetic Fiber Construction in lab .pptxPavel ( NSTU)
Synthetic fiber production is a fascinating and complex field that blends chemistry, engineering, and environmental science. By understanding these aspects, students can gain a comprehensive view of synthetic fiber production, its impact on society and the environment, and the potential for future innovations. Synthetic fibers play a crucial role in modern society, impacting various aspects of daily life, industry, and the environment. ynthetic fibers are integral to modern life, offering a range of benefits from cost-effectiveness and versatility to innovative applications and performance characteristics. While they pose environmental challenges, ongoing research and development aim to create more sustainable and eco-friendly alternatives. Understanding the importance of synthetic fibers helps in appreciating their role in the economy, industry, and daily life, while also emphasizing the need for sustainable practices and innovation.
Biological screening of herbal drugs: Introduction and Need for
Phyto-Pharmacological Screening, New Strategies for evaluating
Natural Products, In vitro evaluation techniques for Antioxidants, Antimicrobial and Anticancer drugs. In vivo evaluation techniques
for Anti-inflammatory, Antiulcer, Anticancer, Wound healing, Antidiabetic, Hepatoprotective, Cardio protective, Diuretics and
Antifertility, Toxicity studies as per OECD guidelines
How to Make a Field invisible in Odoo 17Celine George
It is possible to hide or invisible some fields in odoo. Commonly using “invisible” attribute in the field definition to invisible the fields. This slide will show how to make a field invisible in odoo 17.
Macroeconomics- Movie Location
This will be used as part of your Personal Professional Portfolio once graded.
Objective:
Prepare a presentation or a paper using research, basic comparative analysis, data organization and application of economic information. You will make an informed assessment of an economic climate outside of the United States to accomplish an entertainment industry objective.
BER PERFORMANCE ANALYSIS OF OFDM IN COGNITIVE RADIO NETWORK IN RAYLEIGH FADING CHANNEL
1. International Journal of Technical Research and Applications e-ISSN: 2320-8163,
www.ijtra.com Volume 1, Issue 3 (july-August 2013), PP. 60-64
60 | P a g e
BER PERFORMANCE ANALYSIS OF OFDM IN COGNITIVE RADIO NETWORK IN RAYLEIGH FADING CHANNEL
Sonali Gupta1, Dr. Arun Kumar2
1Electronics & Communication, IFTM University Moradabad, India,
2Electronics & Communication, IFTM University Moradabad, India,
ABSTRACT: Orthogonal frequency division multiplexing (OFDM) now a day is becoming a popular modulation technique for cognitive radio networks (CRN). It is only because it can provide large data rates and is sufficiently robust in the face of radio channel impairments. Digital modulation techniques provide efficient evolution for our wireless mobile communications by increasing the capacity, speed and quality of a wireless networks. In this paper, we concentrate on digital modulation schemes, such as QPSK and BPSK over an Rayleigh fading channel to analyze the performance of an OFDM system in terms of bit error rate (BER). Inter carrier interference (ICI) is the major drawback of OFDM. We have chosen pulse shaping schemes, improved sinc power pulses and raised cosine filter for ICI cancelation. All simulation work is done using MATLAB and results shows improvement in BER when ICI cancelation schemes are applied.
Keywords – Cognitive radio network (CRN), OFDM, Rayleigh fading, BPSK, QPSK, Inter carrier interference (ICI).
1. INTRODUCTION
Wireless technology is embedded in our daily routine life. These devices use a finite amount of radio spectrum. As the number of devices increase, they compete for bandwidth and they have to face bandwidth scarcity problem. Moreover, traditional fixed spectrum allocation policy can no longer meet the needs and services of the wireless users. According to Federal Communications Commission (FCC), temporal and geographical variations in the utilization of the assigned spectrum range from 15% to 85% in current spectrum allocation policies [1]. To combat this problem J Motila first time proposes the concept of Cognitive Radio Network (CRN). Cognitive radio technology has opened new doors to emerging applications. This technology can serve as a facilitator of communications for other devices which may operate in different band and/or have incompatible wireless interfaces. Similarly, this technology can also be used to provide opportunistic access to large parts of the underutilized spectrum in cellular networks. In his paper J. Motila Define Cognitive Radio as
“The point in which wireless personal digital assistants and the related networks are sufficiently computationally intelligent about radio resources and related computer to computer communications to detect user communication needs as a function of use context, and to provide radio resources and wireless services most appropriate to those needs” [2].
As wireless applications are becoming more sophisticated and are widely used, the demand for high data- rate communications will increase substantially. Therefore, in addition of being frequency agile, a communication system should be able to achieve high data-rates for transmission. The Multicarrier modulation (MCM) approach can support huge data-rates by dividing the stream into several parallel bit streams, each with a lower bit rate, and modulating these sub- streams with different subcarriers [3].
In this paper we will study orthogonal frequency division multiplexing (OFDM), which is a multicarrier modulation scheme. CRN uses OFDM for data transmission at lower bit rate (BER). In this paper we will study BER analysis of OFDM system in cognitive radio network. Several schemes are also proposed so that BER can be improved and inter carrier interference (ICI) can be minimized.
2. International Journal of Technical Research and Applications e-ISSN: 2320-8163,
www.ijtra.com Volume 1, Issue 3 (july-August 2013), PP. 60-64
61 | P a g e
2. ORTHOGONAL FREQUENCY DIVISION MULTIPLEXING (OFDM)
OFDM is a multi-carrier transmission technique that divides the available spectrum into subcarriers, with each subcarrier containing a low rate data stream. The subcarriers have appropriate spacing and pass band filter shape to satisfy orthogonality. As compared to classical parallel data system, frequency division multiplexing (FDM), where a guard band is necessary between the subcarriers which results in an inefficient usage of spectrum.
Transmitter
i/p
data
o/p
data
Receiver
Figure 1- ODFM system block
The schematic diagram of the OFDM system is depicted in Figure 1. Each OFDM symbol can be generated as follows [4]. The bit stream is split into parallel data streams using the serial-to- parallel (S/P) converter. Afterwards, the parallel streams are passed into an inverse fast Fourier transformation (IFFT) to generate a time sequence of the streams. Subsequently, the OFDM symbol time sequences are extended by adding a cyclic extension called the cyclic prefix (CP). The CP is a copy of the last part of the symbol that is added in the beginning of the sequences and should be larger than the network delay spread in order to mitigate the inter-symbol interference (ISI) generated by the arrival of different OFDM symbols with different delay. The resulting digital signal is converted into an analogue one and transmitted through the channel.
At the receiver side, the signal is reconverted again into digital one and the fast Fourier transformation (FFT) is performed on the received streams after removing the CP. Finally, the parallel streams are gathered into single stream as the original transmitted one. The OFDM baseband equivalent is formed by taking the inverse discrete Fourier transform (IDFT) to a set of complex input symbols {Xk} and adding a cyclic prefix [5]. This can be written mathematically as
(1)
Where {k} is the set of data subcarrier indices and is a subset of the set {0, 1, · · · ,N − 1}, N is the IDFT size, C is the length of the cyclic prefix in number of samples, and T = C + N is the length of the OFDM symbol in number of samples. l denotes the lth OFDM symbol while gT (n) is a rectangular pulse shape that can be expressed as
(2)
any two subcarriers in OFDM are orthogonal in the time interval T.
3. OFDM SIGNAL TO NOISE RATIO (SNR) ANALYSIS IN RAYLEIGH FADING CHANNEL
The SNR is defined as the ratio of the desired signal power to the noise power [6]. The SNR indicates reliability of transmission link between the transmitter and receiver, and is accepted as a standard measure of signal quality. The mean SNR can be given by the ratio of the mean signal power and mean noise power as follows [7]:
E (
) =
=
(3)
where E(·) denotes an expectation operator and
denotes the SNR at i‟th subchannel. Suppose we consider a frequency non-selective slow fading channel, i.e. flat channel response, where the channel magnitude response E(|Hi|2) is flat over the spectrum band. The deactivation of subcarriers due to incumbent users will result in a non-zero ISO. This would also filter out a portion of the channel magnitude response,
S/P
CP
inserter
IFFT
CP
remover
FFT
P/S
Channel
3. International Journal of Technical Research and Applications e-ISSN: 2320-8163,
www.ijtra.com Volume 1, Issue 3 (july-August 2013), PP. 60-64
62 | P a g e
which results in an increase in the magnitude of E(|Hi|2). Then, the SNR gain is given by:
=
(4)
Where
Noise power spectral density
B = Bandwidth
= Incumbent Spectral occupancy (ISP)
In case of frequency selective multipath channel, the channel magnitude response E(|Hi|2) is not flat over the spectrum. Thus, deactivating a portion of the spectrum would also flatten a portion of the channel magnitude response, which results in a random increase in the magnitude of E(|Hi|2).
4. PULSE SHAPING APPROACH IN OFDM
In spite of various advantages OFDM suffer from one major drawback Inter Carrier Interference (ICI) [8]. When ICI is increased than orthogonality in OFDM transmission can no longer be maintained. Various researchers are working to minimize the effect of ICI in OFDM transmission. We are going to discuss two pulse shaping approach in OFDM so that ICI can be minimized.
4.1 IMPROVED SINC POWER PULSE (ISP)
The purpose of pulse shaping is to reduce the main lobe as well as side lobe, as the side lobes contain the ICI power and the main lobe contains peak power. The improved sinc power pulse (ISP) is inspired from the conventional SP pulse shape [9]. The conventional sinc pulse is defined below.
PSP(f) = sincm (fT) (5)
The Fourier transform of the continuous time Improved Sinc power pulse (ISP) is described by modifying SP as follows.
PISP(f) = exp{-a(fT)2}sincm (fT) (6)
Where „a‟ is a design parameter to adjust the amplitude and m is the degree of the sinc function. It is observed that the magnitude spectral of side lobe is maximum for rectangular pulse and minimum for ISP pulse shapes.
4.2 RAISED COSINE FILTER
The raised-cosine filter is, a good candidate to be used for OFDM sidelobe suppression due to its ability to minimize inter carrier interference (ICI) as well as its relatively straightforward implementation based on mathematically tractable expressions. The ideal raised-cosine filter impulse response is defined as [6]:
h(t) = sinc
(7)
Where T is the reciprocal of the symbol rate.
The frequency response of an ideal raised-cosine filter consists of unity gain at low frequencies, a raised-cosine function in the middle frequencies, and really total attenuation at high frequencies. The width of the middle frequencies is defined by the roll off factor β, where 0 < β < 1. The term β is a measure of the excess bandwidth (BW) of the filter, i.e., the BW occupied beyond the Nyquist BW of 1/2T. Mathematically, the frequency response of a raised- cosine filter can be written as [11]
H(f)
=
(8)
Using the Fourier transform pair h(t)←F →H(f), we can modulate H(f) to the center frequency
by multiplying h(t) by a factor of e2πfct. Therefore, the new raised-cosine filter impulse response becomes
= sinc
5. SIMULATION RESULTS
In this paper, we have evaluated the BER performance of an OFDM system with two digital modulation schemes, namely
4. International Journal of Technical Research and Applications e-ISSN: 2320-8163,
www.ijtra.com Volume 1, Issue 3 (july-August 2013), PP. 60-64
63 | P a g e
BPSK (Binary Phase Shift Keying) and QPSK (Quadrature
Phase Shift Keying) [10], over a Rayleigh fading channel.
OFDM is a powerful modulation technique to achieve high
data rate and is able to eliminate inter symbol interference
(ISI). It is computationally efficient due to its use of FFT
techniques for implementing modulation and demodulation
functions. The simulation parameters used for the model are
as given below.
Simulation work is done using MATLAB.
Simulated and theoretical SNR Verses BER curves for BPSK
and QPSK modulation schemes are shown in figure 2 and 3.
BER performance of QPSK is better than BPSK. It is clear
from the report of federal communication commission that
using QPSK data can be transmitted at twice of data rate as
compared to BPSK modulation. The greatest penalty that is
paid for using QPSK is that QPSK transmitters and receivers
are very much complicated and costly in comparison to
BPSK.
We have chosen BPSK modulation scheme when
pulse shaping scheme for ICI cancelation are applied. The
pulse shaping technique is applied to OFDM system with a
fixed normalized frequency offset value fT = 0.25. Pulse
shapes RC with roll off rate = 0.5 and ISP with different
design parameters (m=2, a=0.5, 1) are considered in this
simulation. From figure 4 it is clear that BER can be
improved when using raised cosine filter for ICI reduction.
Further improvement in BER can be achieved when using
ISP. Hence with the proposed pulse shaping approach
drawback of OFDM system, i.e. ICI are reduced. So
performance enhancement of the OFDM system is observed.
TABLE- 1
Parameter Specification
IFFT size 64
No of carrier in OFDM symbol 52
Channel Rayleigh
Frequency Offset value 0.25
Modulation BPSK/ QPSK
0 5 10 15 20 25 30 35
10
-4
10
-3
10
-2
10
-1
10
0
SNR
BER
Simulation of BER for QPSK in OFDM
Theoritical
Simulated
Figure 2- Simulated and theoretical Bit error rate of QPSK in
OFDM in Rayleigh fading channel.
0 5 10 15 20 25 30 35 40
10
-5
10
-4
10
-3
10
-2
10
-1
10
0
SNR
BER
Bit error probability curve for BPSK using OFDM
simulated
theoritical
Figure 3- Simulated and theoretical Bit error rate of BPSK in
OFDM in Rayleigh fading channel.
5. International Journal of Technical Research and Applications e-ISSN: 2320-8163,
www.ijtra.com Volume 1, Issue 3 (july-August 2013), PP. 60-64
64 | P a g e
Figure 4- BER performance of BPSK-OFDM system for without and with Pulse Shaping ΔfT= 0.25.
REFERENCES
[1] Federal Communications Commission, “Spectrum policy task force report,” ET Docket No. 02-135, 2002.
[2] Mitola J., Maguire G.: „Cognitive radio: making software radios more personal‟, IEEE Pers. Communications, 1999,6, (4), pp. 13–18.
[3] J. A. C. Bingham, “Multicarrier modulation for data transmission: an idea whose time has come,” IEEE Commun. Mag., vol. 28, pp. 5–14, May 1990.
[4] R. Rajbanshi, “OFDM-based cognitive radio for DSA networks”, Ph.D. Thesis, University of Kansas, Lawrence, Kan, USA, 2007.
[5] S. B. Weinstein and P. M. Ebert, “Data transmission by frequency division multiplexing using the discretefourier transform,” IEEE Trans. Commun. Technol., vol. 19, pp. 628 – 634, Oct 1971.
[6] J. G. Proakis, Digital Communications. New York, NY: McGraw Hill, 2001.
[7] T. S. Rappaport, Wireless Communications: Principles and Practice. Upper Saddle River, NJ, USA: Prentice Hall, 1996.
[8] X. CAI and G. B. Giannakis, “Low-complexity ICI suppression for OFDM over time- and frequency selective Rayleigh fading channels,” in Proc. Asilomar Conf. Signals, Systems and Computers, Nov. 2002.
[9] H. M. Mourad, “Reducing ICI in OFDM Systems using a Proposed Pulse Shape,” Wireless Person. Communication, Vol. 40, pp. 41–48, 2006.
[10] V. Kumbasar and O. Kucur, “ICI Reduction in OFDM Systems by using Improved Sinc Power Pulse,” Digital Signal Processing, Vol.17, Issue 6, pp. 997-1006, Nov. 2007.
[11] Sami H. O. Salih, Mamoun M. A. Suliman, “Implementation of Adaptive Modulation and Coding Techniques using Matlab,” 53rd International Symposium ELMAR-2011, 14-16 September 2011, Zadar, Croatia.