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
An Optimized Energy Detection Scheme For Spectrum Sensing In Cognitive RadioIJERD Editor
With rapid growth of wireless devices, the Scarcity of Spectrum resources arises ,due to the improper and inefficient usage of available spectrum band. This problem can be alleviated by Cognitive radio . The major function of the cognitive radio rely on efficient sensing of available spectrum and Spectrum sensing techniques have been used to enhance the detection performance. Among these techniques, Energy detection is considered to be the implemented in practice because of less complexity. In this paper we propose an Adaptive threshold scheme which improves the detection performance under low SNR region. In this paper, noise uncertainty factor is considered wherein the Probability of error is minimized in various SNR regions.
Performance Analysis and Comparative Study of Cognitive Radio Spectrum Sensin...IOSR Journals
In cognitive radio, spectrum sensing is an emergent technology to find available and unused
spectrum for increasing spectrum utilization and to overcome spectrum scarcity problem without harmful
interference to licensed users. Cooperative spectrum sensing is used to give reliable performance in terms of
detection probability and false alarm probability as well as in order to reduce fading, noise and shadowing
effects on cognitive radio users. In this paper according to detection performance and complexity various
cooperative spectrum sensing schemes have been discussed. We have analyzed spectrum sensing with different fusion rules and their comparative behavior has also been studied. Furthermore, we introduced AND-OR fusion rules in 2-bit and 3-bit hard combination schemes
PAPR Reduction using Tone Reservation Method in OFDM SignalIJASRD Journal
In this paper, we are going to propose ‘Tone Reservation’ technique to reduce PAPR (Peak to Average Power Ratio) in OFDM signal using new algorithm. It is less complex and also calculates its own threshold value at the time of communication. It also calculates its PRT signal while other algorithms requiring predetermined threshold and PRT. It modifies the data by ‘bit by bit’ comparison with a modified copy of itself (algorithm modified) thus scaling the peaks as and providing a decent BER and good PAPR reduction.
Design of matched filter for radar applicationselelijjournal
The aim of this paper is to present the details of signal processing techniques in Military RADARS . These
techniques are strongly based on mathematics and specially on stochastic processes. Detecting a target in
a noisy environment is a many folds sequential process. The signal processing chain only provides to the
overall system boolean indicators stating the presence (or not) of targets inside the coverage area. It is
part of the strategical operation of the radar. This paper mainly focuses on Design of Matched filter and
generation of chirp Signal.
An Optimized Energy Detection Scheme For Spectrum Sensing In Cognitive RadioIJERD Editor
With rapid growth of wireless devices, the Scarcity of Spectrum resources arises ,due to the improper and inefficient usage of available spectrum band. This problem can be alleviated by Cognitive radio . The major function of the cognitive radio rely on efficient sensing of available spectrum and Spectrum sensing techniques have been used to enhance the detection performance. Among these techniques, Energy detection is considered to be the implemented in practice because of less complexity. In this paper we propose an Adaptive threshold scheme which improves the detection performance under low SNR region. In this paper, noise uncertainty factor is considered wherein the Probability of error is minimized in various SNR regions.
Performance Analysis and Comparative Study of Cognitive Radio Spectrum Sensin...IOSR Journals
In cognitive radio, spectrum sensing is an emergent technology to find available and unused
spectrum for increasing spectrum utilization and to overcome spectrum scarcity problem without harmful
interference to licensed users. Cooperative spectrum sensing is used to give reliable performance in terms of
detection probability and false alarm probability as well as in order to reduce fading, noise and shadowing
effects on cognitive radio users. In this paper according to detection performance and complexity various
cooperative spectrum sensing schemes have been discussed. We have analyzed spectrum sensing with different fusion rules and their comparative behavior has also been studied. Furthermore, we introduced AND-OR fusion rules in 2-bit and 3-bit hard combination schemes
PAPR Reduction using Tone Reservation Method in OFDM SignalIJASRD Journal
In this paper, we are going to propose ‘Tone Reservation’ technique to reduce PAPR (Peak to Average Power Ratio) in OFDM signal using new algorithm. It is less complex and also calculates its own threshold value at the time of communication. It also calculates its PRT signal while other algorithms requiring predetermined threshold and PRT. It modifies the data by ‘bit by bit’ comparison with a modified copy of itself (algorithm modified) thus scaling the peaks as and providing a decent BER and good PAPR reduction.
Design of matched filter for radar applicationselelijjournal
The aim of this paper is to present the details of signal processing techniques in Military RADARS . These
techniques are strongly based on mathematics and specially on stochastic processes. Detecting a target in
a noisy environment is a many folds sequential process. The signal processing chain only provides to the
overall system boolean indicators stating the presence (or not) of targets inside the coverage area. It is
part of the strategical operation of the radar. This paper mainly focuses on Design of Matched filter and
generation of chirp Signal.
Comparative analysis on an exponential form of pulse with an integer and non-...IJERA Editor
The theme of this paper is to make a fundamental comparative analysis on time-bandwidth product of a short
duration pulse, whose amplitude is varied with an exponent as an integer and non-integer. The time-bandwidth
product is the most significant factor in pulse compression techniques which is used very often in radar systems
for better detection of the target and resolving the ambiguities in the both range and velocity with the help of
ambiguity function. In this paper, different exponents have been used and it is observed that the non-integer
exponents are giving slightly better quantitative parameters like time-bandwidth product, relative sidelobe level
and main lobe widths. To improve these quantitative parameters, phase variations have been incorporated with
the differentiated pulses of the original exponential signal. Finally, the modulation has also been applied on the
pulses to observe the results in real practical applications. From all these analysis, it is concluded that the
differentiated non-integer exponential pulse with bi-polar variations is giving better pulse compression
requirements (time-bandwidth product, peak sidelobe level, 3-dB beamwidth and main lobe widths) compared
to all other pulse forms. The outputs of the matched filter are also observed for each pulse shape.
MMSE and ZF Analysis of Macrodiversity MIMO Systems and Wimax Networks over F...IJERA Editor
We consider the large scale MIMO systems in which the number of users are gradually increased at that time the receiving antennas performance also decreased gradually. In contrast, almost no analytical results are available for macro diversity systems where both the sources and receive antennas are widely separated. Here, receive antennas experience unequal average SNRs from a source and receiver antenna receives a different average SNR from each source. Although this is an extremely difficult problem,In this paper, we provide approximate distributions for the output SNR of a ZF receiver and the output signal to interference plus noise ratio (SINR) of an MMSE receiver. In addition, simple high SNR approximations are provided for the symbol error rate (SER) of both receivers assuming M-PSK or M-QAM modulations .For better performance of receivers we can also implement the MMSE and ZF analysis in Wimax networks.
Standard radar detection process requires that the sensor output is compared to a predetermined threshold. The
threshold is selected based on a-priori knowledge available and/or certain assumptions. However, any
knowledge and/or assumptions become in adequate due to the presence of multiple targets with varying signal
return and usually non stationary background. Thus, any predetermined threshold may result in either increased
false alarm rate or increased track loss. Even approaches where the threshold is adaptively varied will not
perform well in situations when the signal return from the target of interest is too low compared to the average
level of the background .Track-before-detect techniques eliminate the need for a detection threshold and provide
detecting and tracking targets with lower signal-to-noise ratios than standard methods. However, although trackbefore-
detect techniques eliminate
the need for detection threshold at sensor's signal processing stage, they often use tuning thresholds at the output
of the filtering stage .This paper presents a computerized simulation model for target detection process.
Moreover, the proposed model method is based on the target motion models, the output of the detection
process can easily be employed for maneuvering target tracking.
A New Approach for Error Reduction in Localization for Wireless Sensor Networksidescitation
Localization is one of the most challenging and
important issues in wireless sensor networks (WSNs),
especially if cost effective approaches are demanded. Distance
measurement based on RSSI (Received Signal Strength
Indication) is a low cost and low complexity of the distance
measurement technique, and it is widely applied in the range-
based localization of the WSN. The RSS (Received Signal
Strength) used to estimate the distance between an unknown
node and a number of reference nodes with known co-ordinates.
Location of the target node is then determined by trilateration.
Log-normal shadowing model, can better describe the
relationship between the RSSI value and distance. Non-line
of sight and multipath transmission effects as the indoor
environment, the distance error or ranging error is large. In
this paper, experimental results that are carried out to analyze
the sensitivity of RSSI measurements in an indoor
environment for various power levels are presented. Location
error influenced by distance measure error and network
connectivity is analyzed.
Index Terms—
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.
Comparative Study of Different Non-Cooperative Techniques in Cognitive RadioRSIS International
Wireless technology is expanding its domain and with it
is growing the need for more frequencies for communication.
Cognitive radio offers a solution to this problem by using the
concept of Dynamic spectrum access instead of fixed spectrum
allocation. Such radios are capable of sensing the RF spectrum
for identifying idle frequency bands. It then transmits
opportunistically so as to avoid interference with primary user
over same band. In cognitive radio, intelligent spectrum sensing
forms the major and most important part. Out of the various
sensing techniques, we will give an overview of some of the
prominent non-cooperative techniques. The paper deals with
comparative study of these methods.
Dwpt Based FFT and Its Application to SNR Estimation in OFDM SystemsCSCJournals
In this paper, wavelet packet (WP) based FFT and its application to SNR estimation is proposed. OFDM systems demodulate data using FFT. The proposed solution computes the exact FFT using WP and its computational complexity is of the same order as FFT, i.e. O (Nlog2 N). SNR estimation is done inside wavelet packet based FFT block unlike previous SNR estimations techniques which perform SNR estimation after FFT. Wavelet packet analyzed data is used to perform SNR estimation in colored noise. The proposed estimator takes into consideration the different noise power levels of the colored noise over the OFDM sub-carriers. The OFDM band is divided into several sub-bands using wavelet packet and noise in each sub-band is considered white. The second-order statistics of the transmitted OFDM preamble are calculated in each sub-band and the power noise is estimated. The proposed estimator is compared with Reddy’s estimator for colored noise in terms of mean squared error (MSE).
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
A combined spectrum sensing method based DCT for cognitive radio system IJECEIAES
In this paper a new hybrid blind spectrum sensing method is proposed. The method is designed to enhance the detection performance of Conventional Energy Detector (CED) through combining it with a proposed sensing module based on Discrete Cosine Transform (DCT) coefficient’s relationship as operation mode at low Signal to Noise Ratio (SNR) values. In the proposed sensing module a certain factor called Average Ratio (AR) represent the ratio of energy in DCT coefficients is utilized to identify the presence of the Primary User (PU) signal. The simulation results show that the proposed method improves PU detection especially at low SNR values.
OFDM PAPR Reduction Using Hybrid Partial Transmit Sequences Based On Cuckoo S...IJERA Editor
The past decade has seen many radical changes and achievements in the field of wireless communication. Applications of wireless communication have grown swiftly in the recent past. This rigorous growth leads to more throughput over wireless channels along with increased reliability. But still the bandwidth demands are endless and increasing day by day. Today we need to constantly work towards achieving reliable wireless communication with high spectral efficiency, low complexity and good error performance results. Orthogonal frequency division multiplexing (OFDM) technique is a promising technique in this regard as it offers high data rate and reliable communications over various fading channels. But the main drawback of OFDM is the high peak to average power ratio (PAPR). In this paper we present the technique to reduce the PAPR using Cuckoo Search Algorithm in multicarrier modulation system. Simulation results show that the proposed scheme considerably outperforms the conventional system.
Analysis of Space Time Codes Using Modulation TechniquesIOSR Journals
Abstract: In this Paper, Analysis of channel codes for improving the data rate and reliability of communication over fading channels using multiple transmit antennas has been considered. The codes, namely ’Space Time Codes’ render full diversity and amend coding gain. Performance criteria for designing such codes, under this assumption that the fading is slow and nonselective frequency, is also analysed. Under this research, Study of Frame Error Rate(FER) and outage capacity is compared for different no. Of transmit and receive antennas as well as for different modulation techniques. According to theoretical results FER decreases with increasing SNR and No. Of receiving antennas. Numerical and practical result shows that FER decreases with increasing SNR and no. Of receiving antennas. Keywords: Space time Block Codes ,Space time trellis Codes,Frame Error Rate(FER),Outage capacity,Pairwise Error Probability
International Journal of Engineering and Science Invention (IJESI)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.
International Journal of Engineering Research and Applications (IJERA) is a team of researchers not publication services or private publications running the journals for monetary benefits, we are association of scientists and academia who focus only on supporting authors who want to publish their work. The articles published in our journal can be accessed online, all the articles will be archived for real time access.
Our journal system primarily aims to bring out the research talent and the works done by sciaentists, academia, engineers, practitioners, scholars, post graduate students of engineering and science. This journal aims to cover the scientific research in a broader sense and not publishing a niche area of research facilitating researchers from various verticals to publish their papers. It is also aimed to provide a platform for the researchers to publish in a shorter of time, enabling them to continue further All articles published are freely available to scientific researchers in the Government agencies,educators and the general public. We are taking serious efforts to promote our journal across the globe in various ways, we are sure that our journal will act as a scientific platform for all researchers to publish their works online.
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.
Comparative analysis on an exponential form of pulse with an integer and non-...IJERA Editor
The theme of this paper is to make a fundamental comparative analysis on time-bandwidth product of a short
duration pulse, whose amplitude is varied with an exponent as an integer and non-integer. The time-bandwidth
product is the most significant factor in pulse compression techniques which is used very often in radar systems
for better detection of the target and resolving the ambiguities in the both range and velocity with the help of
ambiguity function. In this paper, different exponents have been used and it is observed that the non-integer
exponents are giving slightly better quantitative parameters like time-bandwidth product, relative sidelobe level
and main lobe widths. To improve these quantitative parameters, phase variations have been incorporated with
the differentiated pulses of the original exponential signal. Finally, the modulation has also been applied on the
pulses to observe the results in real practical applications. From all these analysis, it is concluded that the
differentiated non-integer exponential pulse with bi-polar variations is giving better pulse compression
requirements (time-bandwidth product, peak sidelobe level, 3-dB beamwidth and main lobe widths) compared
to all other pulse forms. The outputs of the matched filter are also observed for each pulse shape.
MMSE and ZF Analysis of Macrodiversity MIMO Systems and Wimax Networks over F...IJERA Editor
We consider the large scale MIMO systems in which the number of users are gradually increased at that time the receiving antennas performance also decreased gradually. In contrast, almost no analytical results are available for macro diversity systems where both the sources and receive antennas are widely separated. Here, receive antennas experience unequal average SNRs from a source and receiver antenna receives a different average SNR from each source. Although this is an extremely difficult problem,In this paper, we provide approximate distributions for the output SNR of a ZF receiver and the output signal to interference plus noise ratio (SINR) of an MMSE receiver. In addition, simple high SNR approximations are provided for the symbol error rate (SER) of both receivers assuming M-PSK or M-QAM modulations .For better performance of receivers we can also implement the MMSE and ZF analysis in Wimax networks.
Standard radar detection process requires that the sensor output is compared to a predetermined threshold. The
threshold is selected based on a-priori knowledge available and/or certain assumptions. However, any
knowledge and/or assumptions become in adequate due to the presence of multiple targets with varying signal
return and usually non stationary background. Thus, any predetermined threshold may result in either increased
false alarm rate or increased track loss. Even approaches where the threshold is adaptively varied will not
perform well in situations when the signal return from the target of interest is too low compared to the average
level of the background .Track-before-detect techniques eliminate the need for a detection threshold and provide
detecting and tracking targets with lower signal-to-noise ratios than standard methods. However, although trackbefore-
detect techniques eliminate
the need for detection threshold at sensor's signal processing stage, they often use tuning thresholds at the output
of the filtering stage .This paper presents a computerized simulation model for target detection process.
Moreover, the proposed model method is based on the target motion models, the output of the detection
process can easily be employed for maneuvering target tracking.
A New Approach for Error Reduction in Localization for Wireless Sensor Networksidescitation
Localization is one of the most challenging and
important issues in wireless sensor networks (WSNs),
especially if cost effective approaches are demanded. Distance
measurement based on RSSI (Received Signal Strength
Indication) is a low cost and low complexity of the distance
measurement technique, and it is widely applied in the range-
based localization of the WSN. The RSS (Received Signal
Strength) used to estimate the distance between an unknown
node and a number of reference nodes with known co-ordinates.
Location of the target node is then determined by trilateration.
Log-normal shadowing model, can better describe the
relationship between the RSSI value and distance. Non-line
of sight and multipath transmission effects as the indoor
environment, the distance error or ranging error is large. In
this paper, experimental results that are carried out to analyze
the sensitivity of RSSI measurements in an indoor
environment for various power levels are presented. Location
error influenced by distance measure error and network
connectivity is analyzed.
Index Terms—
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.
Comparative Study of Different Non-Cooperative Techniques in Cognitive RadioRSIS International
Wireless technology is expanding its domain and with it
is growing the need for more frequencies for communication.
Cognitive radio offers a solution to this problem by using the
concept of Dynamic spectrum access instead of fixed spectrum
allocation. Such radios are capable of sensing the RF spectrum
for identifying idle frequency bands. It then transmits
opportunistically so as to avoid interference with primary user
over same band. In cognitive radio, intelligent spectrum sensing
forms the major and most important part. Out of the various
sensing techniques, we will give an overview of some of the
prominent non-cooperative techniques. The paper deals with
comparative study of these methods.
Dwpt Based FFT and Its Application to SNR Estimation in OFDM SystemsCSCJournals
In this paper, wavelet packet (WP) based FFT and its application to SNR estimation is proposed. OFDM systems demodulate data using FFT. The proposed solution computes the exact FFT using WP and its computational complexity is of the same order as FFT, i.e. O (Nlog2 N). SNR estimation is done inside wavelet packet based FFT block unlike previous SNR estimations techniques which perform SNR estimation after FFT. Wavelet packet analyzed data is used to perform SNR estimation in colored noise. The proposed estimator takes into consideration the different noise power levels of the colored noise over the OFDM sub-carriers. The OFDM band is divided into several sub-bands using wavelet packet and noise in each sub-band is considered white. The second-order statistics of the transmitted OFDM preamble are calculated in each sub-band and the power noise is estimated. The proposed estimator is compared with Reddy’s estimator for colored noise in terms of mean squared error (MSE).
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
A combined spectrum sensing method based DCT for cognitive radio system IJECEIAES
In this paper a new hybrid blind spectrum sensing method is proposed. The method is designed to enhance the detection performance of Conventional Energy Detector (CED) through combining it with a proposed sensing module based on Discrete Cosine Transform (DCT) coefficient’s relationship as operation mode at low Signal to Noise Ratio (SNR) values. In the proposed sensing module a certain factor called Average Ratio (AR) represent the ratio of energy in DCT coefficients is utilized to identify the presence of the Primary User (PU) signal. The simulation results show that the proposed method improves PU detection especially at low SNR values.
OFDM PAPR Reduction Using Hybrid Partial Transmit Sequences Based On Cuckoo S...IJERA Editor
The past decade has seen many radical changes and achievements in the field of wireless communication. Applications of wireless communication have grown swiftly in the recent past. This rigorous growth leads to more throughput over wireless channels along with increased reliability. But still the bandwidth demands are endless and increasing day by day. Today we need to constantly work towards achieving reliable wireless communication with high spectral efficiency, low complexity and good error performance results. Orthogonal frequency division multiplexing (OFDM) technique is a promising technique in this regard as it offers high data rate and reliable communications over various fading channels. But the main drawback of OFDM is the high peak to average power ratio (PAPR). In this paper we present the technique to reduce the PAPR using Cuckoo Search Algorithm in multicarrier modulation system. Simulation results show that the proposed scheme considerably outperforms the conventional system.
Analysis of Space Time Codes Using Modulation TechniquesIOSR Journals
Abstract: In this Paper, Analysis of channel codes for improving the data rate and reliability of communication over fading channels using multiple transmit antennas has been considered. The codes, namely ’Space Time Codes’ render full diversity and amend coding gain. Performance criteria for designing such codes, under this assumption that the fading is slow and nonselective frequency, is also analysed. Under this research, Study of Frame Error Rate(FER) and outage capacity is compared for different no. Of transmit and receive antennas as well as for different modulation techniques. According to theoretical results FER decreases with increasing SNR and No. Of receiving antennas. Numerical and practical result shows that FER decreases with increasing SNR and no. Of receiving antennas. Keywords: Space time Block Codes ,Space time trellis Codes,Frame Error Rate(FER),Outage capacity,Pairwise Error Probability
International Journal of Engineering and Science Invention (IJESI)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.
International Journal of Engineering Research and Applications (IJERA) is a team of researchers not publication services or private publications running the journals for monetary benefits, we are association of scientists and academia who focus only on supporting authors who want to publish their work. The articles published in our journal can be accessed online, all the articles will be archived for real time access.
Our journal system primarily aims to bring out the research talent and the works done by sciaentists, academia, engineers, practitioners, scholars, post graduate students of engineering and science. This journal aims to cover the scientific research in a broader sense and not publishing a niche area of research facilitating researchers from various verticals to publish their papers. It is also aimed to provide a platform for the researchers to publish in a shorter of time, enabling them to continue further All articles published are freely available to scientific researchers in the Government agencies,educators and the general public. We are taking serious efforts to promote our journal across the globe in various ways, we are sure that our journal will act as a scientific platform for all researchers to publish their works online.
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.
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.
Removal of chromium (vi) by activated carbon derived from mangifera indicaeSAT 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
Human action recognition using local space time features and adaboost svmeSAT 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
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
Discovering adaptive wireless sensor network using β synchronizereSAT 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
Design and development of load sharing multipath routing protcol for mobile a...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.
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.
A software framework for dynamic modeling of dc motors at robot jointseSAT 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
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.
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
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology.
Performance Evaluation of Energy Detector Based Spectrum Sensing for Cognitiv...IJECEIAES
This paper presents the performance evaluation of the Energy Detector technique, which is one of the most popular Spectrum Sensing (SS) technique for Cognitive Radio (CR). SS is the ability to detect the presence of a Primary User (PU) (i.e. licensed user) in order to allow a Secondary User (SU) (i.e unlicensed user) to access PU’s frequency band using CR, so that the available frequency bands can be used efficiently. We used for implementation an Universal Software Radio Peripheral (USRP), which is the most used Software Defined Radio (SDR) device for research in wireless communications. Experimental measurements show that the Energy Detector can obtain good performances in low Signal to Noise Ratio (SNR) values. Furthermore, computer simulations using MATLAB are closer to those of USRP measurements.
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
Performance Analysis and Comparative Study of Cognitive Radio Spectrum Sensin...IOSR Journals
Abstract : In cognitive radio, spectrum sensing is an emergent technology to find available and unused spectrum for increasing spectrum utilization and to overcome spectrum scarcity problem without harmful interference to licensed users. Cooperative spectrum sensing is used to give reliable performance in terms of detection probability and false alarm probability as well as in order to reduce fading, noise and shadowing effects on cognitive radio users. In this paper according to detection performance and complexity various cooperative spectrum sensing schemes have been discussed. We have analyzed spectrum sensing with different fusion rules and their comparative behavior has also been studied. Furthermore, we introduced AND-OR fusion rules in 2-bit and 3-bit hard combination schemes. Keywords - Cognitive radio, cooperative spectrum sensing, energy detector, spectrum sensing, hard combination
Heterogeneous Spectrum Sensing in Cognitive Radio Network using Traditional E...IJEACS
The accurate spectrum sensing is a predominant
aspect of any competent CR system. Efficient spectrum sensing
enables a CR terminal to detect the spectrum holes (underutilized
spectral bands) by providing high spectral resolution, thereby
accrediting opportunistic transmission in the licensed band to the
CR. In order to facilitate a good spectrum management and its
efficient use a hybrid method for the detection of the spectrum
with the purpose of detecting the presence of bands of
unoccupied frequencies is proposed. The method used are
traditional energy detection and matched filter with changing
number of secondary users using each technique and finally a
centralized cooperative spectrum sensing network which employs
hard combination at the fusion centre.
Performance Comparison of Energy Detection Based Spectrum Sensing for Cogniti...irjes
With the rapid deployment of new wireless devices and applications, the last decade has witnessed a growing
demand for wireless radio spectrum. However, the policy of fixed spectrum assignment produces a bottleneck for more
efficient spectrum utilization, such that a great portion of the licensed spectrum is severely under-utilized. So the concept of
cognitive radio was introduced to address this issue.The inefficient usage of the limited spectrum necessitates the
development of dynamic spectrum access techniques, where users who have no spectrum licenses, also known as secondary
users, are allowed to use the temporarily unused licensed spectrum. For this purpose we have to know the presence or
absence of primary users for spectrum usage. So spectrums sensing is one of the major requirements of cognitive radio.Many
spectrum sensing techniques have been developed to sense the presence or absence of a licensed user. This paper evaluates
the performance of the energy detection based spectrum sensing technique in noisy and fading environments.The
performance of the energy detection technique will be evaluated by use of Receiver Operating Characteristics (ROC) curves
over additive white Gaussian noise (AWGN) and fading channels.
A novel scheme to improve the spectrum sensing performanceIJCNCJournal
Due to limited availability of spectrum for license
d users only, the need for secondary access by unli
censed
users is increasing. Cognitive radio turns out to b
e helping this situation because all that is needed
is a
technique that could efficiently detect the empty s
paces and provide them to the secondary devices wit
hout
causing any interference to the primary (licensed)
users. Spectrum sensing is the foremost function of
the
cognitive radio which senses the environment for wh
ite spaces. Energy detection is one of the various
spectrum sensing techniques that are under research
. Earlier it was shown that energy detection works
better under AWGN channel as compared to Rayleigh c
hannel, however the conventional spectrum sensing
techniques have a high probability of false alarm a
nd also show a better probability of detection for
higher
values of SNR. There is a need for a new technique
that shows a reduced probability of false alarm as
well
as an increase in the probability of detection for
lower values of SNR. In the present work the conven
tional
energy detection technique has been enhanced to get
better results.
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.
Performance Analysis of Fading Channels on Cooperative Mode Spectrum Sensing ...ijtsrd
Spectrum sensing is the main feature of cognitive radio technology. Spectrum sensing gives an idea of detecting the presence of the primary users in a licensed spectrum. The sensing of radio spectrum is an essential problem in cognitive radio CR networks, where secondary users SUs need to detect the presence of primary users PUs before they use the spectrum allocated to PUs. The detection of primary user status and the spectrum sensing are the major issues in cognitive radio systems. We employ one of the simplest and most efficient Spectrum Sensing technique, the cooperative spectrum sensing with three different digital modulation techniques BPSK, QPSK, 16 QAM. In this paper, we analyze the performance of the cooperative spectrum sensing technique with BPSK, QPSK, 16 QAM modulation techniques over Rayleigh fading Channel. Further, we analyze the performance and BER Bit Error Rate of cooperative spectrum sensing under Rayleigh fading and AWGN channels. The investigation and analysis on cooperative spectrum sensing with above digital modulation techniques can be utilized for future reference of spectrum sensing in the CR networks over AWGN and Rayleigh fading channels. Sangram Singh | Rashmi Raj "Performance Analysis of Fading Channels on Cooperative Mode Spectrum Sensing Technique for Cognitive Radio" Published in International Journal of Trend in Scientific Research and Development (ijtsrd), ISSN: 2456-6470, Volume-4 | Issue-3 , April 2020, URL: https://www.ijtsrd.com/papers/ijtsrd30338.pdf Paper Url :https://www.ijtsrd.com/engineering/electronics-and-communication-engineering/30338/performance-analysis-of-fading-channels-on-cooperative-mode-spectrum-sensing-technique-for-cognitive-radio/sangram-singh
Spectrum Sensing Detection with Sequential Forward Search in Comparison to Kn...IJMTST Journal
FCC is currently working on the concept of white space users “borrowing” spectrum from free license
holders temporarily to improve the spectrum utilization.
This project provides a relation between a Pf and the SNR value of any spectrum detector to have a
certain performance. Previous spectrum sensing detection techniques are only suitable for Low SNR and
are based on signal information values. But these methods are purely narrow band spectrum applications
In order to overcome the above said drawbacks we propose a novel method of spectrum sensing method
and is suitable for low and high SNR values, the sensed spectrum applicable for wide band applications.
Our proposed method does not require signal information at the receiver and channel information, because
this flexibility sensing rate is very high compared to previous techniques.
Isolated words recognition using mfcc, lpc and neural networkeSAT Journals
Abstract Automatic speech recognition is an important topic of speech processing. This paper presents the use of an Artificial Neural Network (ANN) for isolated word recognition. The Pre-processing is done and voiced speech is detected based on energy and zero crossing rates (ZCR). The proposed approach used in speech recognition is Mel Frequency Cepstral Coefficients (MFCC) and combine features of both MFCC and Linear Predictive Coding (LPC). The back-propagation is used as a classifier. The recognition accuracy is increased when combine features of both LPC and MFCC are used as compared to only MFCC approach using Neural Network as a classifier.. Keywords: Pre-processing, Mel frequency Cepstral Coefficient (MFCC), Linear Predictive Coding (LPC), Artificial Neural Network (ANN).
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.
Performance Analysis of Noise Uncertainty in Energy Detection Spectrum Sensin...Onyebuchi nosiri
Abstract—The Performance of Energy Detection (ED) spectrum sensing technique depends on threshold selected for deciding the presence or absence of Primary User. In practice, noise density is uncertain and can affect the performance of ED in that sometimes presence of signals is confused for their absence (noise) and vice versa. The traditional energy detection algorithm was based on fixed threshold and has been observed to be inefficient under noise uncertainty. The technique requires optimizing the threshold to be more flexible to check the noise uncertainty effects. The paper therefore proposed an algorithm relative to a unique environment which in effect considered the dynamism relatively and dependent on the environment. The results obtained demonstrated significant improvement compared to the traditional energy detection system
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About
Indigenized remote control interface card suitable for MAFI system CCR equipment. Compatible for IDM8000 CCR. Backplane mounted serial and TCP/Ethernet communication module for CCR remote access. IDM 8000 CCR remote control on serial and TCP protocol.
• Remote control: Parallel or serial interface.
• Compatible with MAFI CCR system.
• Compatible with IDM8000 CCR.
• Compatible with Backplane mount serial communication.
• Compatible with commercial and Defence aviation CCR system.
• Remote control system for accessing CCR and allied system over serial or TCP.
• Indigenized local Support/presence in India.
• Easy in configuration using DIP switches.
Technical Specifications
Indigenized remote control interface card suitable for MAFI system CCR equipment. Compatible for IDM8000 CCR. Backplane mounted serial and TCP/Ethernet communication module for CCR remote access. IDM 8000 CCR remote control on serial and TCP protocol.
Key Features
Indigenized remote control interface card suitable for MAFI system CCR equipment. Compatible for IDM8000 CCR. Backplane mounted serial and TCP/Ethernet communication module for CCR remote access. IDM 8000 CCR remote control on serial and TCP protocol.
• Remote control: Parallel or serial interface
• Compatible with MAFI CCR system
• Copatiable with IDM8000 CCR
• Compatible with Backplane mount serial communication.
• Compatible with commercial and Defence aviation CCR system.
• Remote control system for accessing CCR and allied system over serial or TCP.
• Indigenized local Support/presence in India.
Application
• Remote control: Parallel or serial interface.
• Compatible with MAFI CCR system.
• Compatible with IDM8000 CCR.
• Compatible with Backplane mount serial communication.
• Compatible with commercial and Defence aviation CCR system.
• Remote control system for accessing CCR and allied system over serial or TCP.
• Indigenized local Support/presence in India.
• Easy in configuration using DIP switches.
New optimization scheme for cooperative spectrum sensing taking different snr in cognitive radio networks
1. IJRET: International Journal of Research in Engineering and Technology eISSN: 2319-1163 | pISSN: 2321-7308
__________________________________________________________________________________________
Volume: 03 Issue: 04 | Apr-2014, Available @ http://www.ijret.org 597
NEW OPTIMIZATION SCHEME FOR COOPERATIVE SPECTRUM
SENSING TAKING DIFFERENT SNR IN COGNITIVE RADIO
NETWORKS
Harsh N. Thakkar1
, Kiran R. Parmar2
1
M.E, Electronics & communication dept, L D College of engineering, India
2
Professor, Electronics & Communication dept, Govt. Engineering College, Gandhinagar, India
Abstract
This paper proposes new method to optimize the overall performance in hard cooperative spectrum sensing in cognitive radio.
Optimization strategy is proposed in order to optimize the overall performance by variation of SNR. Here given strategy contributes to
the methods in the literature by taking their performances to the peak point. Additionally, the effects of spectrum sensing technique
type that used locally at each CR, the local SNR, and the total number of cooperated CRs on the optimal fusion rule are found. The
energy detector (ED) spectrum sensing technique is examined as local spectrum sensing techniques. Here different error levels are
founded by variation of SNR. The optimal number of CRs form minimizing the error at SNR 5,10,13,17,18,20 are found to be 4 or 5,
5, 5 or 6, 6, 8, 9 respectively.
Keywords: cognitive radio; spectrum sensing; cooperative spectrum sensing; cooperative spectrum sensing optimization
----------------------------------------------------------------------***------------------------------------------------------------------------
1. INTRODUCTION
Providing frequencies for the new wireless technologies
increases the demand for spectrum, which is a scarce resource.
An ineffective use of the already licensed spectrum, meets that
high demand for the same [6].The technique of cognitive radio
(CR), has been proposed to deal with such problems [11]. In
Cognitive Radio system, the CR, which is called secondary
user, senses its surrounding radio frequency (RF) environment
to detect the vacant frequencies, which are being unused by
their licensed users. These users are called primary users.
Cognitive radio can use these vacant frequencies
opportunistically to transmit and receive its data by adapting its
transmission parameters like frequency. It enables secondary
user/network to utilize the spectrum. So, it is the strategy
proposed as a promising technology to improve spectrum
utilization efficiency.
2. EASE OF USE
As defining the vacant frequencies is the way to exploit these
unoccupied bands; the spectrum sensing is a key functional
factor in cognitive radio. Energy detector (ED) is a one of the
best spectrum sensing technique that does not require prior
information about the Primary signal. This technique is
simple, but that at the expense of its performance at low SNR.
Cooperative spectrum sensing technique is proposed to
eliminate the effects of shadowing and multipath fading on the
spectrum sensing of primary user, when only one CR module
is used [10]. In hard cooperation, each CR senses and decides
about the PR‟s signal in a specific frequency band, then a
binary information 1 or 0 is sent to the CR base station(CR-
BS) via dedicated control channel (CC), representing the
presence or absence of Primary signal. Then, the CR-Base
station decides on the all received digits using logical fusion
rule. Different strategies and factors have been investigated to
optimize the hard cooperative sensing performance by
minimizing the total error probability, or maximizing the
probability of detection [4]. It was achieved by optimizing the
number of cooperated Cognitive radios and the threshold. The
author has taken the global probability of detection in “OR‟
and “AND‟ fusion rules to peak by fixing the global false
alarm probability In [7]. In [3] Strategies to decrease the total
error probability under Neyman Pearson, and Bayesian
criterions have been studied. In this paper, we add our
contribution to the hard cooperative spectrum sensing
optimization area, by adding an important factor that can be
controlled in term to minimize the total error probability. Our
work here can be applied to all mentioned optimization
strategies to take them to the optimist point All optimization
published works, focused only on ED as a local spectrum
sensing. In this paper, the effects of using different numbers of
CRs, different SNR on the optimal fusion rule have been
investigated. The paper is organized as follows: Section III
defines the models for the local spectrum sensing techniques
when ED locally. Section IV presents the theoretical work of
the cooperative spectrum sensing, that includes the
optimization for the ED, and total number of CRs. Section V
concludes the paper.
2. IJRET: International Journal of Research in Engineering and Technology eISSN: 2319-1163 | pISSN: 2321-7308
__________________________________________________________________________________________
Volume: 03 Issue: 04 | Apr-2014, Available @ http://www.ijret.org 598
3. LOCAL SPECTRUM SENSING
We have a number of G (or r = 1, 2. . . G) CRs in the CR
network, where each CR performs spectrum sensing locally
using Energy Detection. Each CR transceiver is supported by
(N-IFFT/FFT) processers to perform both tasks of
communication and sensing the environment. The primary
transmitter with N subcarriers (N-IFFT/FFT) transmits
OFDM-QPSK signal with energy over each sub carrier, and
Ts which is symbol duration. So, each CR estimates the power
within each subcarrier in the frequency domain, with = 0,
1/N, 2/N. . . N-1/N are the bins of normalized frequency.
When we have fading environment where there are P
resolvable paths between the PR’s transmitter and CR’s
receiver, , p= 0, 1 … P-1 represents the discrete – time
channel impulse response between PR’s transmitter and CR’s
receiver. The hypothesis test which is binary for CR spectrum
sensing at the lth time is given by:
: (1)
(2)
Where l=0, 1 . . . L-1 is OFDM block’s index,
and denote the CR received, noise and PR
transmitted samples. Additive white Gaussian noise with zero
mean distorts the transmitted PR signal. The discrete
frequency response of the channel is obtained by taking the N
point FFT, with N > P as given below:
H( fi ) = (3)
Here H0represents the absence of PR’s signal and
H1represents its presence. Now to evaluate performance of the
local spectrum sensing using the rth
CR user, the probability of
detection Pd,r (fi), the probability of false alarm Pf,r (fi), and
the probability of missed detection Pm,r (fi) at each frequency
bin fi are considered based on the Neyman-Pearson (NP)
criterion. The probability that the rth
CR detector decides
correctly the presence of the PR’s signal is Pd,r (fi).The
probability that the rth
CR detector decides the PR’s signal is
present when it is absent is Pf,r (fi) . Lastly, is the probability
that the rth
CR fails to detect the PR’s signal when it is present
is Pm,r (fi) .
As following the same work in [4], we assume that all CRs are
much closed to each others in distances. Hence , wireless
environments here can be assumed as an identical and
independent in the CR‟s network, and SNR = for
each CR.
So, the Pd,r (fi), Pf,r (fi), and Pm,r (fi) will be replaced by
Pd(fi), Pf(fi), and Pm(fi) respectively in the remaining part of
this paper.
In General, the probabilities of detection Pd(fi), and false
alarm Pd(fi) can be defined for normally distributed statistic as
follow:
Pd(fi) = P( DEC (fi) >y/H1)
= Q( ) (4)
Pf(fi) = P( DEC (fi) > y/H0)
= Q( ) (5)
Finally, the probability of missed detection Pm(fi) can be
defined as:
Pm(fi) = P( DEC (fi) < y/H1)
= 1 - Q( ) (6)
Where DCE (fi) , is the decision statistic at. The symbol Q(x)
is the complementary cumulative distribution function, Q(x)
= ; it calculates the tail probability, and represents
the threshold that we choose. Here we note that, y can be
controlled based on L (threshold).Threshold’s values are
chosen based on .In this paper we examine the technique of
local spectrum sensing at each CR receiver; the Energy
Detector In the next two sub-sections a brief about technique
is provided.
3.1 Energy Detector
In this scheme, the received signal is sampled to generate a
finite discrete time samples series {xt ; t= 0, 1 . . . N-1}, where
t index of time. These samples are dot multiplied with
rectangular window. Hence, for each frequency bin ,fi the
decision statistic is computed by the summed energy over
samples as:
DECED(fi) = |^2 (7)
On the basis of central limit theorem, when L is large (e.g.
L>10),the decision statistic can be approximated to normal
distribution with the mean as given:
3. IJRET: International Journal of Research in Engineering and Technology eISSN: 2319-1163 | pISSN: 2321-7308
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Volume: 03 Issue: 04 | Apr-2014, Available @ http://www.ijret.org 599
E[DECED(fi)] = L for H0
= L(|H(fi)|^2 Es + forH1 (8)
and variance is defined as given:
E[DECED(fi)] = 2L for H0
= 2L (2|H(fi)|^2 Es + for H1 (9)
Here different local probabilities of ED-based spectrum
sensing can be evaluated by substituting (7) and (8), into (3)-
(5).
4. HARD COOPERATIVE SPECTRUM SENSING
The spectrum sensing technique used locally at each CR has
been described theoretically when ED is used. Generally, the
cooperation in spectrum sensing is achieved when a number of
CRs in the CR‟s network send their local decisions to the CR-
BS via Communication Channel. Then after, CR-BS combines
these decisions and decides finally about the presence of PR’s
signal in frequency bin fi. Here we note that, in our work, we
are interested to examine the performance when the power
spectrum is sensed at fi when the whole band under sensing is
occupied by PR’s signal in the case of H1. The hard
cooperative spectrum sensing starts from performing local
spectrum sensing using ED, The decision that rth
CR makes is
represented by binary digit br=’1’,or H0represented by binary
digit br=’0’, based on its own local decision statistics. At the
end, the CR-BS combines the received digits from different
CRs to declare the final decision about the presence of
primary signal.
All the received binary digits at the CR-BS from the different
CRs, in the CR network, are fused together to declare the final
decision using the logic rule as given below:
DECCOP (fi) = >= g for H1
= < g for H0 (10)
Where H1 represents that the final decision that has been
made by the CR-BS, stating that the PR’s signal is present in
fi, and H0 represents the PR signal’s absence. Number of CRs
g that decides the presence of PR’s signal at fi, determines the
type of fusion rule at CR Base Station. When g=1 out of total
G CRs, the fusion rule is “OR”, the fusion rule is AND if only
and if all g=G CRs decides H1 case. Lastly when 1<g<G the
“VOTING” fusion rule is applied.
In order to evaluate the cooperative spectrum sensing
performance, we define three joint probabilities; the joint
probability of detection, Qd(fi) the joint probability of false
alarm Qf (fi), and the joint probability of missed detection
Qm (fi). The joint probability of detection can be written as
given below:
Qd (fi)= P( DECCOP (fi) >= g/H1)
=
= (11)
And the joint probability of false alarm Qf(fi) can be written
as given below:
Qf(fi)= P( DECCOP (fi) >= g/H0)
=
= (12)
Here we note that DEC(fi) here means the decision statistic of
the used local sensing. So, finally the joint probability of
missed detection can be written as follows:
Qm (fi) = P( DECCOP (fi) < g/H1)
= 1 – Qd (fi) (13)
Now the total error probability of the cooperative CR
spectrum sensing is defined as given below [4]:
Qerror = Qm (fi) + Qf (fi) (14)
4.1 Local Spectrum Sensing Technique
To examine the performance optimization, of the hard
cooperative spectrum sensing, when local spectrum sensing
techniques are used; the total error probability Qerror are
evaluated at frequency bin fi, using Energy Detection. As we
mentioned earlier in this paper, the different probabilities will
be computed at a specific frequency bin fi. We have G = 10
CRs co-operate the spectrum sensing decisions, at a CR-BS, in
the CR’s network. The local spectrum sensing techniques is
ED. The local SNR = 10db, and L = 10 samples (i.e., OFDM
blocks) are used locally for sensing. Here fig. 1 shows the total
error probability ( Qerror) versus the chosen local threshold
for SNR = 10 db & g =5 by theoretical method using ED
technique.
4. IJRET: International Journal of Research in Engineering and Technology eISSN: 2319-1163 | pISSN: 2321-7308
__________________________________________________________________________________________
Volume: 03 Issue: 04 | Apr-2014, Available @ http://www.ijret.org 600
Fig. 2 shows the total error probability (Qerror) versus the
chosen local threshold for SNR = 10 db & g = 5 by monte-
carlo simulation method using ED technique.
Here fig. 3 shows the total error probability (Qerror) versus
the chosen local threshold for different number of g out G CRs
that controls the fusion rule in (13) using ED technique. If we
compare the different curves that represent the total error for
different numbers of g in Fig. 3, we observe, there are
noticeable difference in the performance through using g = 1
to 10 as a G=10 fusion rule. Here, g = 10 which represent
“AND” fusion rule, gives high total error compared to the
other curves; it is found that g = 5 gives the minimum total
error (min Qerror) at the Same values of SNR and thresold.
Hence, g = 5 is the optimal fusion rule here (i.e., goptimal =
2).
SNR = 10 db, L = 10
Fig. 1 Total error probability (Qerror ) for g = 5 CRs versus
local threshold when ED is used locally with SNR = 10 db and
L = 10 sensed samples used at each CR.(theoretical)
4.2 Different Number of G CRS
An interesting question now, is the goptimal that achieves min
Qerror same when the number of total CRs is different? Table
I shows the optimal fusion rule and min Q error when SNR is
varied and the ED is used locally, with same number of the
sensed samples (i.e. L = 10). The improvement in the
performance by increasing the total number G for different
SNR at CRs at fixed L, is noticeable. For example, min Qerror
= 0.2511 when SNR=5 db and CRs = 4 or 5, and min=0.00251
when SNR is increased to 10 db and CRS = 5. The increase in
SNR causes decrease in the min Qerrorwith variation in
number of CRs. Furthermore, for fixed SNR if the number of
the total co-operated CRs, G, is increased above optimal then
the Qerror is increased.
SNR = 10 db, L = 10
Fig. 2 Total error probability (Qerror ) for g = 5 CRs versus
local threshold when ED is used locally with SNR = 10 db and
L = 10 sensed samples used at each CR.(monte-carlo
simulation)
SNR = 10 db, L = 10
Fig. 3 Total error probability (Qerror ) for g out of G = 10 CRs
versus local threshold when ED is used locally with SNR= 10
db and L = 10 sensed samples used at each CR
5. IJRET: International Journal of Research in Engineering and Technology eISSN: 2319-1163 | pISSN: 2321-7308
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Volume: 03 Issue: 04 | Apr-2014, Available @ http://www.ijret.org 601
SNR = [5, 10, 13, 17, 18, 20] db, L = 10
Fig. 4 Total error probability (Qerror) for g out of G = 10
CRs versus local threshold when ED is used locally with
SNR= 5, 10, 13, 17, 18, 20 db and L = 10 sensed samples used
at each CR
In Fig. 3 we can see that for different SNRs we get different
results regarding minimum Qerror and goptimal as we change
the SNR error is decreased and also goptimal value is
changing.
Table 1: Optimal number of g CRs for different SNR and its
error level
SNR in db Error level Number of cognitive radio user
5 4 or 5
10 5
13 5 or 6
17 6
18 8
20 9
Table I shows tabular form of fig. 3. It shows the variation in
error level by changing SNR and respective Number of
cognitive radio user.
5. CONCLUSIONS
This paper contributes to the cooperative spectrum sensing
optimization by introducing an efficient optimization factor;
the number of cognitive radio user, G. As at each CR module
we may have different SNR, depending upon the value of
SNR we have derived the total error rate for different g (1 to
10). We have found the goptimal for each SNR. For SNR
value 5, 10, 17, 18, 20 we get goptimal as 4 or 5, 5, 5 or 6, 6,
8, 9.
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